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Sample records for cell size control

  1. Analysis of Noise Mechanisms in Cell-Size Control.

    Science.gov (United States)

    Modi, Saurabh; Vargas-Garcia, Cesar Augusto; Ghusinga, Khem Raj; Singh, Abhyudai

    2017-06-06

    At the single-cell level, noise arises from multiple sources, such as inherent stochasticity of biomolecular processes, random partitioning of resources at division, and fluctuations in cellular growth rates. How these diverse noise mechanisms combine to drive variations in cell size within an isoclonal population is not well understood. Here, we investigate the contributions of different noise sources in well-known paradigms of cell-size control, such as adder (division occurs after adding a fixed size from birth), sizer (division occurs after reaching a size threshold), and timer (division occurs after a fixed time from birth). Analysis reveals that variation in cell size is most sensitive to errors in partitioning of volume among daughter cells, and not surprisingly, this process is well regulated among microbes. Moreover, depending on the dominant noise mechanism, different size-control strategies (or a combination of them) provide efficient buffering of size variations. We further explore mixer models of size control, where a timer phase precedes/follows an adder, as has been proposed in Caulobacter crescentus. Although mixing a timer and an adder can sometimes attenuate size variations, it invariably leads to higher-order moments growing unboundedly over time. This results in a power-law distribution for the cell size, with an exponent that depends inversely on the noise in the timer phase. Consistent with theory, we find evidence of power-law statistics in the tail of C. crescentus cell-size distribution, although there is a discrepancy between the observed power-law exponent and that predicted from the noise parameters. The discrepancy, however, is removed after data reveal that the size added by individual newborns in the adder phase itself exhibits power-law statistics. Taken together, this study provides key insights into the role of noise mechanisms in size homeostasis, and suggests an inextricable link between timer-based models of size control and

  2. Cell size checkpoint control by the retinoblastoma tumor suppressor pathway.

    Science.gov (United States)

    Fang, Su-Chiung; de los Reyes, Chris; Umen, James G

    2006-10-13

    Size control is essential for all proliferating cells, and is thought to be regulated by checkpoints that couple cell size to cell cycle progression. The aberrant cell-size phenotypes caused by mutations in the retinoblastoma (RB) tumor suppressor pathway are consistent with a role in size checkpoint control, but indirect effects on size caused by altered cell cycle kinetics are difficult to rule out. The multiple fission cell cycle of the unicellular alga Chlamydomonas reinhardtii uncouples growth from division, allowing direct assessment of the relationship between size phenotypes and checkpoint function. Mutations in the C. reinhardtii RB homolog encoded by MAT3 cause supernumerous cell divisions and small cells, suggesting a role for MAT3 in size control. We identified suppressors of an mat3 null allele that had recessive mutations in DP1 or dominant mutations in E2F1, loci encoding homologs of a heterodimeric transcription factor that is targeted by RB-related proteins. Significantly, we determined that the dp1 and e2f1 phenotypes were caused by defects in size checkpoint control and were not due to a lengthened cell cycle. Despite their cell division defects, mat3, dp1, and e2f1 mutants showed almost no changes in periodic transcription of genes induced during S phase and mitosis, many of which are conserved targets of the RB pathway. Conversely, we found that regulation of cell size was unaffected when S phase and mitotic transcription were inhibited. Our data provide direct evidence that the RB pathway mediates cell size checkpoint control and suggest that such control is not directly coupled to the magnitude of periodic cell cycle transcription.

  3. Daughter-specific transcription factors regulate cell size control in budding yeast.

    Science.gov (United States)

    Di Talia, Stefano; Wang, Hongyin; Skotheim, Jan M; Rosebrock, Adam P; Futcher, Bruce; Cross, Frederick R

    2009-10-01

    In budding yeast, asymmetric cell division yields a larger mother and a smaller daughter cell, which transcribe different genes due to the daughter-specific transcription factors Ace2 and Ash1. Cell size control at the Start checkpoint has long been considered to be a main regulator of the length of the G1 phase of the cell cycle, resulting in longer G1 in the smaller daughter cells. Our recent data confirmed this concept using quantitative time-lapse microscopy. However, it has been proposed that daughter-specific, Ace2-dependent repression of expression of the G1 cyclin CLN3 had a dominant role in delaying daughters in G1. We wanted to reconcile these two divergent perspectives on the origin of long daughter G1 times. We quantified size control using single-cell time-lapse imaging of fluorescently labeled budding yeast, in the presence or absence of the daughter-specific transcriptional regulators Ace2 and Ash1. Ace2 and Ash1 are not required for efficient size control, but they shift the domain of efficient size control to larger cell size, thus increasing cell size requirement for Start in daughters. Microarray and chromatin immunoprecipitation experiments show that Ace2 and Ash1 are direct transcriptional regulators of the G1 cyclin gene CLN3. Quantification of cell size control in cells expressing titrated levels of Cln3 from ectopic promoters, and from cells with mutated Ace2 and Ash1 sites in the CLN3 promoter, showed that regulation of CLN3 expression by Ace2 and Ash1 can account for the differential regulation of Start in response to cell size in mothers and daughters. We show how daughter-specific transcriptional programs can interact with intrinsic cell size control to differentially regulate Start in mother and daughter cells. This work demonstrates mechanistically how asymmetric localization of cell fate determinants results in cell-type-specific regulation of the cell cycle.

  4. Daughter-Specific Transcription Factors Regulate Cell Size Control in Budding Yeast

    Science.gov (United States)

    Di Talia, Stefano; Wang, Hongyin; Skotheim, Jan M.; Rosebrock, Adam P.; Futcher, Bruce; Cross, Frederick R.

    2009-01-01

    In budding yeast, asymmetric cell division yields a larger mother and a smaller daughter cell, which transcribe different genes due to the daughter-specific transcription factors Ace2 and Ash1. Cell size control at the Start checkpoint has long been considered to be a main regulator of the length of the G1 phase of the cell cycle, resulting in longer G1 in the smaller daughter cells. Our recent data confirmed this concept using quantitative time-lapse microscopy. However, it has been proposed that daughter-specific, Ace2-dependent repression of expression of the G1 cyclin CLN3 had a dominant role in delaying daughters in G1. We wanted to reconcile these two divergent perspectives on the origin of long daughter G1 times. We quantified size control using single-cell time-lapse imaging of fluorescently labeled budding yeast, in the presence or absence of the daughter-specific transcriptional regulators Ace2 and Ash1. Ace2 and Ash1 are not required for efficient size control, but they shift the domain of efficient size control to larger cell size, thus increasing cell size requirement for Start in daughters. Microarray and chromatin immunoprecipitation experiments show that Ace2 and Ash1 are direct transcriptional regulators of the G1 cyclin gene CLN3. Quantification of cell size control in cells expressing titrated levels of Cln3 from ectopic promoters, and from cells with mutated Ace2 and Ash1 sites in the CLN3 promoter, showed that regulation of CLN3 expression by Ace2 and Ash1 can account for the differential regulation of Start in response to cell size in mothers and daughters. We show how daughter-specific transcriptional programs can interact with intrinsic cell size control to differentially regulate Start in mother and daughter cells. This work demonstrates mechanistically how asymmetric localization of cell fate determinants results in cell-type-specific regulation of the cell cycle. PMID:19841732

  5. Daughter-specific transcription factors regulate cell size control in budding yeast.

    Directory of Open Access Journals (Sweden)

    Stefano Di Talia

    2009-10-01

    Full Text Available In budding yeast, asymmetric cell division yields a larger mother and a smaller daughter cell, which transcribe different genes due to the daughter-specific transcription factors Ace2 and Ash1. Cell size control at the Start checkpoint has long been considered to be a main regulator of the length of the G1 phase of the cell cycle, resulting in longer G1 in the smaller daughter cells. Our recent data confirmed this concept using quantitative time-lapse microscopy. However, it has been proposed that daughter-specific, Ace2-dependent repression of expression of the G1 cyclin CLN3 had a dominant role in delaying daughters in G1. We wanted to reconcile these two divergent perspectives on the origin of long daughter G1 times. We quantified size control using single-cell time-lapse imaging of fluorescently labeled budding yeast, in the presence or absence of the daughter-specific transcriptional regulators Ace2 and Ash1. Ace2 and Ash1 are not required for efficient size control, but they shift the domain of efficient size control to larger cell size, thus increasing cell size requirement for Start in daughters. Microarray and chromatin immunoprecipitation experiments show that Ace2 and Ash1 are direct transcriptional regulators of the G1 cyclin gene CLN3. Quantification of cell size control in cells expressing titrated levels of Cln3 from ectopic promoters, and from cells with mutated Ace2 and Ash1 sites in the CLN3 promoter, showed that regulation of CLN3 expression by Ace2 and Ash1 can account for the differential regulation of Start in response to cell size in mothers and daughters. We show how daughter-specific transcriptional programs can interact with intrinsic cell size control to differentially regulate Start in mother and daughter cells. This work demonstrates mechanistically how asymmetric localization of cell fate determinants results in cell-type-specific regulation of the cell cycle.

  6. Cell Size Regulation in Bacteria

    Science.gov (United States)

    Amir, Ariel

    2014-05-01

    Various bacteria such as the canonical gram negative Escherichia coli or the well-studied gram positive Bacillus subtilis divide symmetrically after they approximately double their volume. Their size at division is not constant, but is typically distributed over a narrow range. Here, we propose an analytically tractable model for cell size control, and calculate the cell size and interdivision time distributions, as well as the correlations between these variables. We suggest ways of extracting the model parameters from experimental data, and show that existing data for E. coli supports partial size control, and a particular explanation: a cell attempts to add a constant volume from the time of initiation of DNA replication to the next initiation event. This hypothesis accounts for the experimentally observed correlations between mother and daughter cells as well as the exponential dependence of size on growth rate.

  7. The TOR Signaling Pathway in Spatial and Temporal Control of Cell Size and Growth

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    Suam Gonzalez

    2017-06-01

    Full Text Available Cell size is amenable by genetic and environmental factors. The highly conserved nutrient-responsive Target of Rapamycin (TOR signaling pathway regulates cellular metabolic status and growth in response to numerous inputs. Timing and duration of TOR pathway activity is pivotal for both cell mass built up as well as cell cycle progression and is controlled and fine-tuned by the abundance and quality of nutrients, hormonal signals, growth factors, stress, and oxygen. TOR kinases function within two functionally and structurally discrete multiprotein complexes, TORC1 and TORC2, that are implicated in temporal and spatial control of cell size and growth respectively; however, recent data indicate that such functional distinctions are much more complex. Here, we briefly review roles of the two complexes in cellular growth and cytoarchitecture in various experimental model systems.

  8. Comparative analysis of cells and proteins of pumpkin plants for the control of fruit size.

    Science.gov (United States)

    Nakata, Yumiko; Taniguchi, Go; Takazaki, Shinya; Oda-Ueda, Naoko; Miyahara, Kohji; Ohshima, Yasumi

    2012-09-01

    Common pumpkin plants (Cucurbita maxima) produce fruits of 1-2 kg size on the average, while special varieties of the same species called Atlantic Giant are known to produce a huge fruit up to several hundred kilograms. As an approach to determine the factors controlling the fruit size in C. maxima, we cultivated both AG and control common plants, and found that both the cell number and cell sizes were increased in a large fruit while DNA content of the cell did not change significantly. We also compared protein patterns in the leaves, stems, ripe and young fruits by two-dimensional (2D) gel electrophoresis, and identified those differentially expressed between them with mass spectroscopy. Based on these results, we suggest that factors in photosynthesis such as ribulose-bisphosphate carboxylase, glycolysis pathway enzymes, heat-shock proteins and ATP synthase play positive or negative roles in the growth of a pumpkin fruit. These results provide a step toward the development of plant biotechnology to control fruit size in the future. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  9. Structure and Electromagnetic Properties of Cellular Glassy Carbon Monoliths with Controlled Cell Size

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    Andrzej Szczurek

    2018-05-01

    Full Text Available Electromagnetic shielding is a topic of high importance for which lightweight materials are highly sought. Porous carbon materials can meet this goal, but their structure needs to be controlled as much as possible. In this work, cellular carbon monoliths of well-defined porosity and cell size were prepared by a template method, using sacrificial paraffin spheres as the porogen and resorcinol-formaldehyde (RF resin as the carbon precursor. Physicochemical studies were carried out for investigating the conversion of RF resin into carbon, and the final cellular monoliths were investigated in terms of elemental composition, total porosity, surface area, micropore volumes, and micro/macropore size distributions. Electrical and electromagnetic (EM properties were investigated in the static regime and in the Ka-band, respectively. Due to the phenolic nature of the resin, the resultant carbon was glasslike, and the special preparation protocol that was used led to cellular materials whose cell size increased with density. The materials were shown to be relevant for EM shielding, and the relationships between those properties and the density/cell size of those cellular monoliths were elucidated.

  10. How Cells Can Control Their Size by Pumping Ions

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    Alan R. Kay

    2017-05-01

    Full Text Available The ability of all cells to set and regulate their size is a fundamental aspect of cellular physiology. It has been known for sometime but not widely so, that size stability in animal cells is dependent upon the operation of the sodium pump, through the so-called pump-leak mechanism (Tosteson and Hoffman, 1960. Impermeant molecules in cells establish an unstable osmotic condition, the Donnan effect, which is counteracted by the operation of the sodium pump, creating an asymmetry in the distribution of Na+ and K+ staving off water inundation. In this paper, which is in part a tutorial, I show how to model quantitatively the ion and water fluxes in a cell that determine the cell volume and membrane potential. The movement of water and ions is constrained by both osmotic and charge balance, and is driven by ion and voltage gradients and active ion transport. Transforming these constraints and forces into a set of coupled differential equations allows us to model how the ion distributions, volume and voltage change with time. I introduce an analytical solution to these equations that clarifies the influence of ion conductances, pump rates and water permeability in this multidimensional system. I show that the number of impermeant ions (x and their average charge have a powerful influence on the distribution of ions and voltage in a cell. Moreover, I demonstrate that in a cell where the operation of active ion transport eliminates an osmotic gradient, the size of the cell is directly proportional to x. In addition, I use graphics to reveal how the physico-chemical constraints and chemical forces interact with one another in apportioning ions inside the cell. The form of model used here is applicable to all membrane systems, including mitochondria and bacteria, and I show how pumps other than the sodium pump can be used to stabilize cells. Cell biologists may think of electrophysiology as the exclusive domain of neuroscience, however the electrical

  11. A novel Drosophila Girdin-like protein is involved in Akt pathway control of cell size

    Energy Technology Data Exchange (ETDEWEB)

    Puseenam, Aekkachai [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Yoshioka, Yasuhide [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Nagai, Rika [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Hashimoto, Reina [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Suyari, Osamu [Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Itoh, Masanobu [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Enomoto, Atsushi [Department of Pathology, Center for Neurological Disease and Cancer, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi 466-8550 (Japan); Takahashi, Masahide [Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Department of Pathology, Center for Neurological Disease and Cancer, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi 466-8550 (Japan); Yamaguchi, Masamitsu, E-mail: myamaguc@kit.ac.jp [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)

    2009-11-15

    The Akt signaling pathway is well known to regulate cell proliferation and growth. Girdin, a novel substrate of Akt, plays a crucial role in organization of the actin cytoskeleton and cell motility under the control of Akt. We here identified a novel Girdin-like protein in Drosophila (dGirdin), which has two isoforms, dGirdin PA and dGirdin PB. dGirdin shows high homology with human Girdin in the N-terminal and coiled-coil domains, while diverging at the C-terminal domain. On establishment of transgenic fly lines, featuring knockdown or overexpression of dGirdin in vivo, overexpression in the wing disc cells induced ectopic apoptosis, implying a role in directing apoptosis. Knockdown of dGirdin in the Drosophila wing imaginal disc cells resulted in reduction of cell size. Furthermore, this was enhanced by half reduction of the Akt gene dose, suggesting that Akt positively regulates dGirdin. In the wing disc, cells in which dGirdin was knocked down exhibited disruption of actin filaments. From these in vivo analyses, we conclude that dGirdin is required for actin organization and regulation of appropriate cell size under control of the Akt signaling pathway.

  12. A novel Drosophila Girdin-like protein is involved in Akt pathway control of cell size

    International Nuclear Information System (INIS)

    Puseenam, Aekkachai; Yoshioka, Yasuhide; Nagai, Rika; Hashimoto, Reina; Suyari, Osamu; Itoh, Masanobu; Enomoto, Atsushi; Takahashi, Masahide; Yamaguchi, Masamitsu

    2009-01-01

    The Akt signaling pathway is well known to regulate cell proliferation and growth. Girdin, a novel substrate of Akt, plays a crucial role in organization of the actin cytoskeleton and cell motility under the control of Akt. We here identified a novel Girdin-like protein in Drosophila (dGirdin), which has two isoforms, dGirdin PA and dGirdin PB. dGirdin shows high homology with human Girdin in the N-terminal and coiled-coil domains, while diverging at the C-terminal domain. On establishment of transgenic fly lines, featuring knockdown or overexpression of dGirdin in vivo, overexpression in the wing disc cells induced ectopic apoptosis, implying a role in directing apoptosis. Knockdown of dGirdin in the Drosophila wing imaginal disc cells resulted in reduction of cell size. Furthermore, this was enhanced by half reduction of the Akt gene dose, suggesting that Akt positively regulates dGirdin. In the wing disc, cells in which dGirdin was knocked down exhibited disruption of actin filaments. From these in vivo analyses, we conclude that dGirdin is required for actin organization and regulation of appropriate cell size under control of the Akt signaling pathway.

  13. The Dynamical Mechanisms of the Cell Cycle Size Checkpoint

    International Nuclear Information System (INIS)

    Feng Shi-Fu; Yang Ling; Yan Jie; Liu Zeng-Rong

    2012-01-01

    Cell division must be tightly coupled to cell growth in order to maintain cell size, whereas the mechanisms of how initialization of mitosis is regulated by cell size remain to be elucidated. We develop a mathematical model of the cell cycle, which incorporates cell growth to investigate the dynamical properties of the size checkpoint in embryos of Xenopus laevis. We show that the size checkpoint is naturally raised from a saddle-node bifurcation, and in a mutant case, the cell loses its size control ability due to the loss of this saddle-node point

  14. Generating size-controlled embryoid bodies using laser direct-write

    International Nuclear Information System (INIS)

    Dias, A D; Corr, D T; Unser, A M; Xie, Y; Chrisey, D B

    2014-01-01

    Embryonic stem cells (ESCs) have the potential to self-renew and differentiate into any specialized cell type. One common method to differentiate ESCs in vitro is through embryoid bodies (EBs), three-dimensional cellular aggregates that spontaneously self-assemble and generally express markers for the three germ layers, endoderm, ectoderm, and mesoderm. It has been previously shown that both EB size and 2D colony size each influence differentiation. We hypothesized that we could control the size of the EB formed by mouse ESCs (mESCs) by using a cell printing method, laser direct-write (LDW), to control both the size of the initial printed colony and the local cell density in printed colonies. After printing mESCs at various printed colony sizes and printing densities, two-way ANOVAs indicated that the EB diameter was influenced by printing density after three days (p = 0.0002), while there was no effect of the printed colony diameter on the EB diameter at the same timepoint (p = 0.74). There was no significant interaction between these two factors. Tukey's honestly significant difference test showed that high-density colonies formed significantly larger EBs, suggesting that printed mESCs quickly aggregate with nearby cells. Thus, EBs can be engineered to a desired size by controlling printing density, which will influence the design of future differentiation studies. Herein, we highlight the capacity of LDW to control the local cell density and colony size independently, at prescribed spatial locations, potentially leading to better stem cell maintenance and directed differentiation. (paper)

  15. Does Ploidy Level Directly Control Cell Size? Counterevidence from Arabidopsis Genetics

    OpenAIRE

    Tsukaya, Hirokazu

    2013-01-01

    Ploidy level affects cell size in many organisms, and ploidy-dependent cell enlargement has been used to breed many useful organisms. However, how polyploidy affects cell size remains unknown. Previous studies have explored changes in transcriptome data caused by polyploidy, but have not been successful. The most naïve theory explaining ploidy-dependent cell enlargement is that increases in gene copy number increase the amount of protein, which in turn increases the cell volume. This hypothes...

  16. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    International Nuclear Information System (INIS)

    Joseph, Bertrand; Hermanson, Ola

    2010-01-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  17. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Bertrand [Department of Oncology-Pathology, Cancer Centrum Karolinska (CCK), Karolinska Institutet, Stockholm (Sweden); Hermanson, Ola, E-mail: ola.hermanson@ki.se [Linnaeus Center in Developmental Biology for Regenerative Medicine (DBRM), Department of Neuroscience, Karolinska Institutet, Stockholm (Sweden)

    2010-05-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  18. Control of cell proliferation, endoreduplication, cell size, and cell death by the retinoblastoma-related pathway in maize endosperm

    KAUST Repository

    Sabelli, Paolo A.

    2013-04-22

    The endospermof cereal grains is one of the most valuable products of modern agriculture. Cereal endosperm development comprises different phases characterized by mitotic cell proliferation, endoreduplication, the accumulation of storage compounds, and programmed cell death. Although manipulation of these processes could maximize grain yield, how they are regulated and integrated is poorly understood. We show that the Retinoblastoma-related (RBR) pathway controls key aspects of endosperm development in maize. Down-regulation of RBR1 by RNAi resulted in up-regulation of RBR3-type genes, as well as the MINICHROMOSOME MAINTENANCE 2-7 gene family and PROLIFERATING CELL NUCLEAR ANTIGEN, which encode essential DNA replication factors. Both the mitotic and endoreduplication cell cycles were stimulated. Developing transgenic endosperm contained 42-58% more cells and ~70% more DNA than wild type, whereas there was a reduction in cell and nuclear sizes. In addition, cell death was enhanced. The DNA content of mature endosperm increased 43% upon RBR1 downregulation, whereas storage protein content and kernel weight were essentially not affected. Down-regulation of both RBR1 and CYCLIN DEPENDENT KINASE A (CDKA);1 indicated that CDKA;1 is epistatic to RBR1 and controls endoreduplication through an RBR1- dependent pathway. However, the repressive activity of RBR1 on downstream targets was independent from CDKA;1, suggesting diversification of RBR1 activities. Furthermore, RBR1 negatively regulated CDK activity, suggesting the presence of a feedback loop. These results indicate that the RBR1 pathway plays a major role in regulation of different processes during maize endosperm development and suggest the presence of tissue/organlevel regulation of endosperm/seed homeostasis.

  19. Single-Cell Analysis of Growth in Budding Yeast and Bacteria Reveals a Common Size Regulation Strategy.

    Science.gov (United States)

    Soifer, Ilya; Robert, Lydia; Amir, Ariel

    2016-02-08

    To maintain a constant cell size, dividing cells have to coordinate cell-cycle events with cell growth. This coordination has long been supposed to rely on the existence of size thresholds determining cell-cycle progression [1]. In budding yeast, size is controlled at the G1/S transition [2]. In agreement with this hypothesis, the size at birth influences the time spent in G1: smaller cells have a longer G1 period [3]. Nevertheless, even though cells born smaller have a longer G1, the compensation is imperfect and they still bud at smaller cell sizes. In bacteria, several recent studies have shown that the incremental model of size control, in which size is controlled by addition of a constant volume (in contrast to a size threshold), is able to quantitatively explain the experimental data on four different bacterial species [4-7]. Here, we report on experimental results for the budding yeast Saccharomyces cerevisiae, finding, surprisingly, that cell size control in this organism is very well described by the incremental model, suggesting a common strategy for cell size control with bacteria. Additionally, we argue that for S. cerevisiae the "volume increment" is not added from birth to division, but rather between two budding events. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Morphology, Growth, and Size Limit of Bacterial Cells

    Science.gov (United States)

    Jiang, Hongyuan; Sun, Sean X.

    2010-07-01

    Bacterial cells utilize a living peptidoglycan network (PG) to separate the cell interior from the surroundings. The shape of the cell is controlled by PG synthesis and cytoskeletal proteins that form bundles and filaments underneath the cell wall. The PG layer also resists turgor pressure and protects the cell from osmotic shock. We argue that mechanical influences alter the chemical equilibrium of the reversible PG assembly and determine the cell shape and cell size. Using a mechanochemical approach, we show that the cell shape can be regarded as a steady state of a growing network under the influence of turgor pressure and mechanical stress. Using simple elastic models, we predict the size of common spherical and rodlike bacteria. The influence of cytoskeletal bundles such as crescentin and MreB are discussed within the context of our model.

  1. Capabilities and Limitations of Tissue Size Control through Passive Mechanical Forces.

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    Jochen Kursawe

    2015-12-01

    Full Text Available Embryogenesis is an extraordinarily robust process, exhibiting the ability to control tissue size and repair patterning defects in the face of environmental and genetic perturbations. The size and shape of a developing tissue is a function of the number and size of its constituent cells as well as their geometric packing. How these cellular properties are coordinated at the tissue level to ensure developmental robustness remains a mystery; understanding this process requires studying multiple concurrent processes that make up morphogenesis, including the spatial patterning of cell fates and apoptosis, as well as cell intercalations. In this work, we develop a computational model that aims to understand aspects of the robust pattern repair mechanisms of the Drosophila embryonic epidermal tissues. Size control in this system has previously been shown to rely on the regulation of apoptosis rather than proliferation; however, to date little work has been done to understand the role of cellular mechanics in this process. We employ a vertex model of an embryonic segment to test hypotheses about the emergence of this size control. Comparing the model to previously published data across wild type and genetic perturbations, we show that passive mechanical forces suffice to explain the observed size control in the posterior (P compartment of a segment. However, observed asymmetries in cell death frequencies across the segment are demonstrated to require patterning of cellular properties in the model. Finally, we show that distinct forms of mechanical regulation in the model may be distinguished by differences in cell shapes in the P compartment, as quantified through experimentally accessible summary statistics, as well as by the tissue recoil after laser ablation experiments.

  2. The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast.

    Science.gov (United States)

    Leitao, Ricardo M; Kellogg, Douglas R

    2017-11-06

    The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast. © 2017 Leitao and Kellogg.

  3. Ste12/Fab1 phosphatidylinositol-3-phosphate 5-kinase is required for nitrogen-regulated mitotic commitment and cell size control.

    Directory of Open Access Journals (Sweden)

    David Cobley

    Full Text Available Tight coupling of cell growth and cell cycle progression enable cells to adjust their rate of division, and therefore size, to the demands of proliferation in varying nutritional environments. Nutrient stress promotes inhibition of Target Of Rapamycin Complex 1 (TORC1 activity. In fission yeast, reduced TORC1 activity advances mitotic onset and switches growth to a sustained proliferation at reduced cell size. A screen for mutants, that failed to advance mitosis upon nitrogen stress, identified a mutant in the PIKFYVE 1-phosphatidylinositol-3-phosphate 5-kinase fission yeast homolog Ste12. Ste12PIKFYVE deficient mutants were unable to advance the cell cycle to reduce cell size after a nitrogen downshift to poor nitrogen (proline growth conditions. While it is well established that PI(3,5P2 signalling is required for autophagy and that Ste12PIKFYVE mutants have enlarged vacuoles (yeast lysosomes, neither a block to autophagy or mutants that independently have enlarged vacuoles had any impact upon nitrogen control of mitotic commitment. The addition of rapamycin to Ste12PIKFYVE deficient mutants reduced cell size at division to suggest that Ste12PIKFYVE possibly functions upstream of TORC1. ste12 mutants display increased Torin1 (TOR inhibitor sensitivity. However, no major impact on TORC1 or TORC2 activity was observed in the ste12 deficient mutants. In summary, Ste12PIKFYVE is required for nitrogen-stress mediated advancement of mitosis to reduce cell size at division.

  4. SCF(SAP) controls organ size by targeting PPD proteins for degradation in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Zhibiao; Li, Na; Jiang, Shan; Gonzalez, Nathalie; Huang, Xiahe; Wang, Yingchun; Inzé, Dirk; Li, Yunhai

    2016-04-06

    Control of organ size by cell proliferation and growth is a fundamental process, but the mechanisms that determine the final size of organs are largely elusive in plants. We have previously revealed that the ubiquitin receptor DA1 regulates organ size by repressing cell proliferation in Arabidopsis. Here we report that a mutant allele of STERILE APETALA (SAP) suppresses the da1-1 mutant phenotype. We show that SAP is an F-box protein that forms part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex and controls organ size by promoting the proliferation of meristemoid cells. Genetic analyses suggest that SAP may act in the same pathway with PEAPOD1 and PEAPOD2, which are negative regulators of meristemoid proliferation, to control organ size, but does so independently of DA1. Further results reveal that SAP physically associates with PEAPOD1 and PEAPOD2, and targets them for degradation. These findings define a molecular mechanism by which SAP and PEAPOD control organ size.

  5. Cell Size and Growth Rate Are Modulated by TORC2-Dependent Signals.

    Science.gov (United States)

    Lucena, Rafael; Alcaide-Gavilán, Maria; Schubert, Katherine; He, Maybo; Domnauer, Matthew G; Marquer, Catherine; Klose, Christian; Surma, Michal A; Kellogg, Douglas R

    2018-01-22

    The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2A Rts1 ) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  7. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.; Gysel, Roman; Beiley, Zach; Miller, Chad E.; Toney, Michael F.; Heeney, Martin; McCulloch, Iain; McGehee, Michael D.

    2009-01-01

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  8. The Rts1 regulatory subunit of protein phosphatase 2A is required for control of G1 cyclin transcription and nutrient modulation of cell size.

    Directory of Open Access Journals (Sweden)

    Karen Artiles

    2009-11-01

    Full Text Available The key molecular event that marks entry into the cell cycle is transcription of G1 cyclins, which bind and activate cyclin-dependent kinases. In yeast cells, initiation of G1 cyclin transcription is linked to achievement of a critical cell size, which contributes to cell-size homeostasis. The critical cell size is modulated by nutrients, such that cells growing in poor nutrients are smaller than cells growing in rich nutrients. Nutrient modulation of cell size does not work through known critical regulators of G1 cyclin transcription and is therefore thought to work through a distinct pathway. Here, we report that Rts1, a highly conserved regulatory subunit of protein phosphatase 2A (PP2A, is required for normal control of G1 cyclin transcription. Loss of Rts1 caused delayed initiation of bud growth and delayed and reduced accumulation of G1 cyclins. Expression of the G1 cyclin CLN2 from an inducible promoter rescued the delayed bud growth in rts1Delta cells, indicating that Rts1 acts at the level of transcription. Moreover, loss of Rts1 caused altered regulation of Swi6, a key component of the SBF transcription factor that controls G1 cyclin transcription. Epistasis analysis revealed that Rts1 does not work solely through several known critical upstream regulators of G1 cyclin transcription. Cells lacking Rts1 failed to undergo nutrient modulation of cell size. Together, these observations demonstrate that Rts1 is a key player in pathways that link nutrient availability, cell size, and G1 cyclin transcription. Since Rts1 is highly conserved, it may function in similar pathways in vertebrates.

  9. MANOVA for Nested Designs with Unequal Cell Sizes and Unequal Cell Covariance Matrices

    Directory of Open Access Journals (Sweden)

    Li-Wen Xu

    2014-01-01

    satisfactorily for various cell sizes and parameter configurations and generally outperforms the AHT test in terms of controlling the nominal size. For the heteroscedastic cases, the PB test outperforms the AHT test in terms of power. In addition, the PB test does not lose too much power when the homogeneity assumption is actually valid.

  10. Real-time control of a microfluidic channel for size-independent deformability cytometry

    International Nuclear Information System (INIS)

    Guan, Guofeng; Chen, Peter C Y; Ong, Chong Jin; Peng, Weng Kung; Bhagat, Ali Asgar; Han, Jongyoon

    2012-01-01

    Mechanical properties of cells can be correlated with various cell states and are now considered as an important class of biophysical markers. Effectiveness of existing high-throughput microfluidic techniques for investigating cell mechanical properties is adversely affected by cell-size variation in a given cell population. In this work, we introduce a new microfluidic system with real-time feedback control to evaluate single-cell deformability while minimizing cell-size dependence of the measurement. Using breast cancer cells (MCF-7), we demonstrate the potential of this system for stiffness profiling of cells in complex, diverse cell populations. (paper)

  11. Details Matter: Noise and Model Structure Set the Relationship between Cell Size and Cell Cycle Timing

    Directory of Open Access Journals (Sweden)

    Felix Barber

    2017-11-01

    Full Text Available Organisms across all domains of life regulate the size of their cells. However, the means by which this is done is poorly understood. We study two abstracted “molecular” models for size regulation: inhibitor dilution and initiator accumulation. We apply the models to two settings: bacteria like Escherichia coli, that grow fully before they set a division plane and divide into two equally sized cells, and cells that form a bud early in the cell division cycle, confine new growth to that bud, and divide at the connection between that bud and the mother cell, like the budding yeast Saccharomyces cerevisiae. In budding cells, delaying cell division until buds reach the same size as their mother leads to very weak size control, with average cell size and standard deviation of cell size increasing over time and saturating up to 100-fold higher than those values for cells that divide when the bud is still substantially smaller than its mother. In budding yeast, both inhibitor dilution or initiator accumulation models are consistent with the observation that the daughters of diploid cells add a constant volume before they divide. This “adder” behavior has also been observed in bacteria. We find that in bacteria an inhibitor dilution model produces adder correlations that are not robust to noise in the timing of DNA replication initiation or in the timing from initiation of DNA replication to cell division (the C+D period. In contrast, in bacteria an initiator accumulation model yields robust adder correlations in the regime where noise in the timing of DNA replication initiation is much greater than noise in the C + D period, as reported previously (Ho and Amir, 2015. In bacteria, division into two equally sized cells does not broaden the size distribution.

  12. A link between mitotic entry and membrane growth suggests a novel model for cell size control.

    Science.gov (United States)

    Anastasia, Steph D; Nguyen, Duy Linh; Thai, Vu; Meloy, Melissa; MacDonough, Tracy; Kellogg, Douglas R

    2012-04-02

    Addition of new membrane to the cell surface by membrane trafficking is necessary for cell growth. In this paper, we report that blocking membrane traffic causes a mitotic checkpoint arrest via Wee1-dependent inhibitory phosphorylation of Cdk1. Checkpoint signals are relayed by the Rho1 GTPase, protein kinase C (Pkc1), and a specific form of protein phosphatase 2A (PP2A(Cdc55)). Signaling via this pathway is dependent on membrane traffic and appears to increase gradually during polar bud growth. We hypothesize that delivery of vesicles to the site of bud growth generates a signal that is proportional to the extent of polarized membrane growth and that the strength of the signal is read by downstream components to determine when sufficient growth has occurred for initiation of mitosis. Growth-dependent signaling could explain how membrane growth is integrated with cell cycle progression. It could also control both cell size and morphogenesis, thereby reconciling divergent models for mitotic checkpoint function.

  13. Cannabidiol Reduces Leukemic Cell Size - But Is It Important?

    Science.gov (United States)

    Kalenderoglou, Nikoletta; Macpherson, Tara; Wright, Karen L

    2017-01-01

    The anti-cancer effect of the plant-derived cannabinoid, cannabidiol, has been widely demonstrated both in vivo and in vitro . However, this body of preclinical work has not been translated into clinical use. Key issues around this failure can be related to narrow dose effects, the cell model used and incomplete efficacy. A model of acute lymphoblastic disease, the Jurkat T cell line, has been used extensively to study the cannabinoid system in the immune system and cannabinoid-induced apoptosis. Using these cells, this study sought to investigate the outcome of those remaining viable cells post-treatment with cannabidiol, both in terms of cell size and tracking any subsequent recovery. The phosphorylation status of the mammalian Target of Rapamycin (mTOR) signaling pathway and the downstream target ribosomal protein S6, were measured. The ability of cannabidiol to exert its effect on cell viability was also evaluated in physiological oxygen conditions. Cannabidiol reduced cell viability incompletely, and slowed the cell cycle with fewer cells in the G2/M phase of the cell cycle. Cannabidiol reduced phosphorylation of mTOR, PKB and S6 pathways related to survival and cell size. The remaining population of viable cells that were cultured in nutrient rich conditions post-treatment were able to proliferate, but did not recover to control cell numbers. However, the proportion of viable cells that were gated as small, increased in response to cannabidiol and normally sized cells decreased. This proportion of small cells persisted in the recovery period and did not return to basal levels. Finally, cells grown in 12% oxygen (physiological normoxia) were more resistant to cannabidiol. In conclusion, these results indicate that cannabidiol causes a reduction in cell size, which persists post-treatment. However, resistance to cannabidiol under physiological normoxia for these cells would imply that cannabidiol may not be useful in the clinic as an anti-leukemic agent.

  14. Size control of giant unilamellar vesicles prepared from inverted emulsion droplets.

    Science.gov (United States)

    Nishimura, Kazuya; Suzuki, Hiroaki; Toyota, Taro; Yomo, Tetsuya

    2012-06-15

    The production of giant lipid vesicles with controlled size and structure will be an important technology in the design of quantitative biological assays in cell-mimetic microcompartments. For establishing size control of giant vesicles, we investigated the vesicle formation process, in which inverted emulsion droplets are transformed into giant unilamellar vesicles (GUVs) when they pass through an oil/water interface. The relationship between the size of the template emulsion and the converted GUVs was studied using inverted emulsion droplets with a narrow size distribution, which were prepared by microfluidics. We successfully found an appropriate centrifugal acceleration condition to obtain GUVs that had a desired size and narrow-enough size distribution with an improved yield so that emulsion droplets can become the template for GUVs. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  15. Hypothyroidism affects differentially the cell size of epithelial cells among oviductal regions of rabbits.

    Science.gov (United States)

    Anaya-Hernández, A; Rodríguez-Castelán, J; Nicolás, L; Martínez-Gómez, M; Jiménez-Estrada, I; Castelán, F; Cuevas, E

    2015-02-01

    Oviductal regions show particular histological characteristics and functions. Tubal pathologies and hypothyroidism are related to primary and secondary infertility. The impact of hypothyroidism on the histological characteristics of oviductal regions has been scarcely studied. Our aim was to analyse the histological characteristics of oviductal regions in control and hypothyroid rabbits. Hypothyroidism was induced by oral administration of methimazole (MMI) for 30 days. For both groups, serum concentrations of thyroid and gonadal hormones were determined. Sections of oviductal regions were stained with the Masson's trichrome technique to analyse both epithelial and smooth muscle layers. The percentage of proliferative epithelial cells (anti-Ki67) in diverse oviductal regions was also quantified. Data were compared with Student t-test, Mann-Whitney U-test, or Fischer's test. In comparison with the control group, the hypothyroid group showed: (i) a low concentration of T3 and T4, but a high level of TSH; (ii) similar values of serum estradiol, progesterone and testosterone; (iii) a large size of ciliated cells in the ampulla (AMP), isthmus (IST) and utero-tubal junction (UTJ); (iv) a large size of secretory cells in the IST region; (v) a low percentage of proliferative secretory cells in the fimbria-infundibulum (FIM-INF) region; and (vi) a similar thickness of the smooth muscle layer and the cross-sectional area in the AMP and IST regions. Modifications in the size of the oviductal epithelium in hypothyroid rabbits could be related to changes in the cell metabolism that may impact on the reproductive functions achieved by oviduct. © 2014 Blackwell Verlag GmbH.

  16. SAD-A kinase controls islet β-cell size and function as a mediator of mTORC1 signaling.

    Science.gov (United States)

    Nie, Jia; Liu, Xiaolei; Lilley, Brendan N; Zhang, Hai; Pan, Y Albert; Kimball, Scot R; Zhang, Jun; Zhang, Weiping; Wang, Li; Jefferson, Leonard S; Sanes, Joshua R; Han, Xiao; Shi, Yuguang

    2013-08-20

    The mammalian target of rapamycin (mTOR) plays an important role in controlling islet β-cell function. However, the underlying molecular mechanisms remain poorly elucidated. Synapses of amphids defective kinase-A (SAD-A) is a 5' adenosine monophosphate-activated protein kinase-related protein kinase that is exclusively expressed in pancreas and brain. In this study, we investigated a role of the kinase in regulating pancreatic β-cell morphology and function as a mediator of mTOR complex 1 (mTORC1) signaling. We show that global SAD-A deletion leads to defective glucose-stimulated insulin secretion and petite islets, which are reminiscent of the defects in mice with global deletion of ribosomal protein S6 kinase 1, a downstream target of mTORC1. Consistent with these findings, selective deletion of SAD-A in pancreas decreased islet β-cell size, whereas SAD-A overexpression significantly increased the size of mouse insulinomas cell lines β-cells. In direct support of SAD-A as a unique mediator of mTORC1 signaling in islet β-cells, we demonstrate that glucose dramatically stimulated SAD-A protein translation in isolated mouse islets, which was potently inhibited by rapamycin, an inhibitor of mTORC1. Moreover, the 5'-untranslated region of SAD-A mRNA is highly structured and requires mTORC1 signaling for its translation initiation. Together, these findings identified SAD-A as a unique pancreas-specific effector protein of mTORC1 signaling.

  17. Effects of ultraviolet irradiation and postirradiation incubation on heterogeneous nuclear RNA size in murine cells

    International Nuclear Information System (INIS)

    Ali, R.; Sauerbier, W.

    1978-01-01

    We have analyzed the decrease in synthesis of individual size classes of heterogeneous nuclear RNA (hnRNA) in ultraviolet (uv)-irradiated Merwin plasmacytoma (MPC-11) cells at various times of postirradiation incubation. HnRNA from nonirradiated control cells is distributed over a wide range from approximately 60S to 5S, with 42S RNA carrying more label than any other size class. HnRNA from uv-irradiated cells shows a dose-dependent shift in size distribution toward lower molecular weight. The size distribution of hnRNA synthesized after prolonged times of postirradiation incubation is restored toward normal, i.e., synthesis of long RNA molecules increases relative to the synthesis of short ones. Analysis of the total number of hnRNA chains synthesized during a 20-min [ 3 H]uridine pulse shows a considerable eduction in their number with increasing uv dose. Murine cell lines are excision-repair-deficient but capable of post replication repair inhibited by caffeine. HnRNA transcripts of cells incubated in its presence were studied. The caffeine, which has no effect on hnRNA size in control cells, inhibits to a considerable extent the restoration of full-length transcripts during postirradiation incubation. The lack of excision repair in MPC-11 was confirmed by the analysis of pyrimidine dimers in trichloracetic acid-insoluble and soluble fractions within 8 h of postirradiation incubation. The size of parental and daughter strand DNA in uv-irradiated cells was correlated with RNA transcript size. The parental DNA in these experiments does not change its size as a consequence of uv exposure and postirradiation incubation. In contrast, daughter DNA strands are short in uv-irradiated cells and they increase in size during postirradiation incubation to reach the size of parental strands after 8 h

  18. Cell size, genome size and the dominance of Angiosperms

    Science.gov (United States)

    Simonin, K. A.; Roddy, A. B.

    2016-12-01

    Angiosperms are capable of maintaining the highest rates of photosynthetic gas exchange of all land plants. High rates of photosynthesis depends mechanistically both on efficiently transporting water to the sites of evaporation in the leaf and on regulating the loss of that water to the atmosphere as CO2 diffuses into the leaf. Angiosperm leaves are unique in their ability to sustain high fluxes of liquid and vapor phase water transport due to high vein densities and numerous, small stomata. Despite the ubiquity of studies characterizing the anatomical and physiological adaptations that enable angiosperms to maintain high rates of photosynthesis, the underlying mechanism explaining why they have been able to develop such high leaf vein densities, and such small and abundant stomata, is still incomplete. Here we ask whether the scaling of genome size and cell size places a fundamental constraint on the photosynthetic metabolism of land plants, and whether genome downsizing among the angiosperms directly contributed to their greater potential and realized primary productivity relative to the other major groups of terrestrial plants. Using previously published data we show that a single relationship can predict guard cell size from genome size across the major groups of terrestrial land plants (e.g. angiosperms, conifers, cycads and ferns). Similarly, a strong positive correlation exists between genome size and both stomatal density and vein density that together ultimately constrains maximum potential (gs, max) and operational stomatal conductance (gs, op). Further the difference in the slopes describing the covariation between genome size and both gs, max and gs, op suggests that genome downsizing brings gs, op closer to gs, max. Taken together the data presented here suggests that the smaller genomes of angiosperms allow their final cell sizes to vary more widely and respond more directly to environmental conditions and in doing so bring operational photosynthetic

  19. Organ size control is dominant over Rb family inactivation to restrict proliferation in vivo.

    Science.gov (United States)

    Ehmer, Ursula; Zmoos, Anne-Flore; Auerbach, Raymond K; Vaka, Dedeepya; Butte, Atul J; Kay, Mark A; Sage, Julien

    2014-07-24

    In mammals, a cell's decision to divide is thought to be under the control of the Rb/E2F pathway. We previously found that inactivation of the Rb family of cell cycle inhibitors (Rb, p107, and p130) in quiescent liver progenitors leads to uncontrolled division and cancer initiation. Here, we show that, in contrast, deletion of the entire Rb gene family in mature hepatocytes is not sufficient for their long-term proliferation. The cell cycle block in Rb family mutant hepatocytes is independent of the Arf/p53/p21 checkpoint but can be abrogated upon decreasing liver size. At the molecular level, we identify YAP, a transcriptional regulator involved in organ size control, as a factor required for the sustained expression of cell cycle genes in hepatocytes. These experiments identify a higher level of regulation of the cell cycle in vivo in which signals regulating organ size are dominant regulators of the core cell cycle machinery. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Cannabidiol Reduces Leukemic Cell Size – But Is It Important?

    Science.gov (United States)

    Kalenderoglou, Nikoletta; Macpherson, Tara; Wright, Karen L.

    2017-01-01

    The anti-cancer effect of the plant-derived cannabinoid, cannabidiol, has been widely demonstrated both in vivo and in vitro. However, this body of preclinical work has not been translated into clinical use. Key issues around this failure can be related to narrow dose effects, the cell model used and incomplete efficacy. A model of acute lymphoblastic disease, the Jurkat T cell line, has been used extensively to study the cannabinoid system in the immune system and cannabinoid-induced apoptosis. Using these cells, this study sought to investigate the outcome of those remaining viable cells post-treatment with cannabidiol, both in terms of cell size and tracking any subsequent recovery. The phosphorylation status of the mammalian Target of Rapamycin (mTOR) signaling pathway and the downstream target ribosomal protein S6, were measured. The ability of cannabidiol to exert its effect on cell viability was also evaluated in physiological oxygen conditions. Cannabidiol reduced cell viability incompletely, and slowed the cell cycle with fewer cells in the G2/M phase of the cell cycle. Cannabidiol reduced phosphorylation of mTOR, PKB and S6 pathways related to survival and cell size. The remaining population of viable cells that were cultured in nutrient rich conditions post-treatment were able to proliferate, but did not recover to control cell numbers. However, the proportion of viable cells that were gated as small, increased in response to cannabidiol and normally sized cells decreased. This proportion of small cells persisted in the recovery period and did not return to basal levels. Finally, cells grown in 12% oxygen (physiological normoxia) were more resistant to cannabidiol. In conclusion, these results indicate that cannabidiol causes a reduction in cell size, which persists post-treatment. However, resistance to cannabidiol under physiological normoxia for these cells would imply that cannabidiol may not be useful in the clinic as an anti-leukemic agent. PMID

  1. Organ Size Control Is Dominant over Rb Family Inactivation to Restrict Proliferation In Vivo

    Directory of Open Access Journals (Sweden)

    Ursula Ehmer

    2014-07-01

    Full Text Available In mammals, a cell’s decision to divide is thought to be under the control of the Rb/E2F pathway. We previously found that inactivation of the Rb family of cell cycle inhibitors (Rb, p107, and p130 in quiescent liver progenitors leads to uncontrolled division and cancer initiation. Here, we show that, in contrast, deletion of the entire Rb gene family in mature hepatocytes is not sufficient for their long-term proliferation. The cell cycle block in Rb family mutant hepatocytes is independent of the Arf/p53/p21 checkpoint but can be abrogated upon decreasing liver size. At the molecular level, we identify YAP, a transcriptional regulator involved in organ size control, as a factor required for the sustained expression of cell cycle genes in hepatocytes. These experiments identify a higher level of regulation of the cell cycle in vivo in which signals regulating organ size are dominant regulators of the core cell cycle machinery.

  2. A chemical screen probing the relationship between mitochondrial content and cell size.

    Directory of Open Access Journals (Sweden)

    Toshimori Kitami

    Full Text Available The cellular content of mitochondria changes dynamically during development and in response to external stimuli, but the underlying mechanisms remain obscure. To systematically identify molecular probes and pathways that control mitochondrial abundance, we developed a high-throughput imaging assay that tracks both the per cell mitochondrial content and the cell size in confluent human umbilical vein endothelial cells. We screened 28,786 small molecules and observed that hundreds of small molecules are capable of increasing or decreasing the cellular content of mitochondria in a manner proportionate to cell size, revealing stereotyped control of these parameters. However, only a handful of compounds dissociate this relationship. We focus on one such compound, BRD6897, and demonstrate through secondary assays that it increases the cellular content of mitochondria as evidenced by fluorescence microscopy, mitochondrial protein content, and respiration, even after rigorous correction for cell size, cell volume, or total protein content. BRD6897 increases uncoupled respiration 1.6-fold in two different, non-dividing cell types. Based on electron microscopy, BRD6897 does not alter the percent of cytoplasmic area occupied by mitochondria, but instead, induces a striking increase in the electron density of existing mitochondria. The mechanism is independent of known transcriptional programs and is likely to be related to a blockade in the turnover of mitochondrial proteins. At present the molecular target of BRD6897 remains to be elucidated, but if identified, could reveal an important additional mechanism that governs mitochondrial biogenesis and turnover.

  3. Evolution of Cell Size Homeostasis and Growth Rate Diversity during Initial Surface Colonization of Shewanella oneidensis.

    Science.gov (United States)

    Lee, Calvin K; Kim, Alexander J; Santos, Giancarlo S; Lai, Peter Y; Lee, Stella Y; Qiao, David F; Anda, Jaime De; Young, Thomas D; Chen, Yujie; Rowe, Annette R; Nealson, Kenneth H; Weiss, Paul S; Wong, Gerard C L

    2016-09-06

    Cell size control and homeostasis are fundamental features of bacterial metabolism. Recent work suggests that cells add a constant size between birth and division ("adder" model). However, it is not known how cell size homeostasis is influenced by the existence of heterogeneous microenvironments, such as those during biofilm formation. Shewanella oneidensis MR-1 can use diverse energy sources on a range of surfaces via extracellular electron transport (EET), which can impact growth, metabolism, and size diversity. Here, we track bacterial surface communities at single-cell resolution to show that not only do bacterial motility appendages influence the transition from two- to three-dimensional biofilm growth and control postdivisional cell fates, they strongly impact cell size homeostasis. For every generation, we find that the average growth rate for cells that stay on the surface and continue to divide (nondetaching population) and that for cells that detach before their next division (detaching population) are roughly constant. However, the growth rate distribution is narrow for the nondetaching population, but broad for the detaching population in each generation. Interestingly, the appendage deletion mutants (ΔpilA, ΔmshA-D, Δflg) have significantly broader growth rate distributions than that of the wild type for both detaching and nondetaching populations, which suggests that Shewanella appendages are important for sensing and integrating environmental inputs that contribute to size homeostasis. Moreover, our results suggest multiplexing of appendages for sensing and motility functions contributes to cell size dysregulation. These results can potentially provide a framework for generating metabolic diversity in S. oneidensis populations to optimize EET in heterogeneous environments.

  4. Cell-size distribution in epithelial tissue formation and homeostasis.

    Science.gov (United States)

    Puliafito, Alberto; Primo, Luca; Celani, Antonio

    2017-03-01

    How cell growth and proliferation are orchestrated in living tissues to achieve a given biological function is a central problem in biology. During development, tissue regeneration and homeostasis, cell proliferation must be coordinated by spatial cues in order for cells to attain the correct size and shape. Biological tissues also feature a notable homogeneity of cell size, which, in specific cases, represents a physiological need. Here, we study the temporal evolution of the cell-size distribution by applying the theory of kinetic fragmentation to tissue development and homeostasis. Our theory predicts self-similar probability density function (PDF) of cell size and explains how division times and redistribution ensure cell size homogeneity across the tissue. Theoretical predictions and numerical simulations of confluent non-homeostatic tissue cultures show that cell size distribution is self-similar. Our experimental data confirm predictions and reveal that, as assumed in the theory, cell division times scale like a power-law of the cell size. We find that in homeostatic conditions there is a stationary distribution with lognormal tails, consistently with our experimental data. Our theoretical predictions and numerical simulations show that the shape of the PDF depends on how the space inherited by apoptotic cells is redistributed and that apoptotic cell rates might also depend on size. © 2017 The Author(s).

  5. Different Amounts of DNA in Newborn Cells of Escherichia coli Preclude a Role for the Chromosome in Size Control According to the "Adder" Model.

    Science.gov (United States)

    Huls, Peter G; Vischer, Norbert O E; Woldringh, Conrad L

    2018-01-01

    According to the recently-revived adder model for cell size control, newborn cells of Escherichia coli will grow and divide after having added a constant size or length, ΔL , irrespective of their size at birth. Assuming exponential elongation, this implies that large newborns will divide earlier than small ones. The molecular basis for the constant size increment is still unknown. As DNA replication and cell growth are coordinated, the constant ΔL could be based on duplication of an equal amount of DNA, ΔG , present in newborn cells. To test this idea, we measured amounts of DNA and lengths of nucleoids in DAPI-stained cells growing in batch culture at slow and fast rates. Deeply-constricted cells were divided in two subpopulations of longer and shorter lengths than average; these were considered to represent large and small prospective daughter cells, respectively. While at slow growth, large and small prospective daughter cells contained similar amounts of DNA, fast growing cells with multiforked replicating chromosomes, showed a significantly higher amount of DNA (20%) in the larger cells. This observation precludes the hypothesis that Δ L is based on the synthesis of a constant ΔG . Growth curves were constructed for siblings generated by asymmetric division and growing according to the adder model. Under the assumption that all cells at the same growth rate exhibit the same time between initiation of DNA replication and cell division (i.e., constant C+D -period), the constructions predict that initiation occurs at different sizes ( Li ) and that, at fast growth, large newborn cells transiently contain more DNA than small newborns, in accordance with the observations. Because the state of segregation, measured as the distance between separated nucleoids, was found to be more advanced in larger deeply-constricted cells, we propose that in larger newborns nucleoid separation occurs faster and at a shorter length, allowing them to divide earlier. We propose

  6. Photoperiod-H1 (Ppd-H1) Controls Leaf Size.

    Science.gov (United States)

    Digel, Benedikt; Tavakol, Elahe; Verderio, Gabriele; Tondelli, Alessandro; Xu, Xin; Cattivelli, Luigi; Rossini, Laura; von Korff, Maria

    2016-09-01

    Leaf size is a major determinant of plant photosynthetic activity and biomass; however, it is poorly understood how leaf size is genetically controlled in cereal crop plants like barley (Hordeum vulgare). We conducted a genome-wide association scan for flowering time, leaf width, and leaf length in a diverse panel of European winter cultivars grown in the field and genotyped with a single-nucleotide polymorphism array. The genome-wide association scan identified PHOTOPERIOD-H1 (Ppd-H1) as a candidate gene underlying the major quantitative trait loci for flowering time and leaf size in the barley population. Microscopic phenotyping of three independent introgression lines confirmed the effect of Ppd-H1 on leaf size. Differences in the duration of leaf growth and consequent variation in leaf cell number were responsible for the leaf size differences between the Ppd-H1 variants. The Ppd-H1-dependent induction of the BARLEY MADS BOX genes BM3 and BM8 in the leaf correlated with reductions in leaf size and leaf number. Our results indicate that leaf size is controlled by the Ppd-H1- and photoperiod-dependent progression of plant development. The coordination of leaf growth with flowering may be part of a reproductive strategy to optimize resource allocation to the developing inflorescences and seeds. © 2016 American Society of Plant Biologists. All rights reserved.

  7. Cytotoxicity and cellular uptake of different sized gold nanoparticles in ovarian cancer cells

    Science.gov (United States)

    Kumar, Dhiraj; Mutreja, Isha; Chitcholtan, Kenny; Sykes, Peter

    2017-11-01

    Nanomedicine has advanced the biomedical field with the availability of multifunctional nanoparticles (NPs) systems that can target a disease site enabling drug delivery and helping to monitor the disease. In this paper, we synthesised the gold nanoparticles (AuNPs) with an average size 18, 40, 60 and 80 nm, and studied the effect of nanoparticles size, concentration and incubation time on ovarian cancer cells namely, OVCAR5, OVCAR8, and SKOV3. The size measured by transmission electron microscopy images was slightly smaller than the hydrodynamic diameter; measured size by ImageJ as 14.55, 38.13, 56.88 and 78.56 nm. The cellular uptake was significantly controlled by the AuNPs size, concentration, and the cell type. The nanoparticles uptake increased with increasing concentration, and 18 and 80 nm AuNPs showed higher uptake ranging from 1.3 to 5.4 μg depending upon the concentration and cell type. The AuNPs were associated with a temporary reduction in metabolic activity, but metabolic activity remained more than 60% for all sample types; NPs significantly affected the cell proliferation activity in first 12 h. The increase in nanoparticle size and concentration induced the production of reactive oxygen species in 24 h.

  8. A genomics approach to understanding the role of auxin in apple (Malus x domestica) fruit size control.

    Science.gov (United States)

    Devoghalaere, Fanny; Doucen, Thomas; Guitton, Baptiste; Keeling, Jeannette; Payne, Wendy; Ling, Toby John; Ross, John James; Hallett, Ian Charles; Gunaseelan, Kularajathevan; Dayatilake, G A; Diak, Robert; Breen, Ken C; Tustin, D Stuart; Costes, Evelyne; Chagné, David; Schaffer, Robert James; David, Karine Myriam

    2012-01-13

    Auxin is an important phytohormone for fleshy fruit development, having been shown to be involved in the initial signal for fertilisation, fruit size through the control of cell division and cell expansion, and ripening related events. There is considerable knowledge of auxin-related genes, mostly from work in model species. With the apple genome now available, it is possible to carry out genomics studies on auxin-related genes to identify genes that may play roles in specific stages of apple fruit development. High amounts of auxin in the seed compared with the fruit cortex were observed in 'Royal Gala' apples, with amounts increasing through fruit development. Injection of exogenous auxin into developing apples at the start of cell expansion caused an increase in cell size. An expression analysis screen of auxin-related genes involved in auxin reception, homeostasis, and transcriptional regulation showed complex patterns of expression in each class of gene. Two mapping populations were phenotyped for fruit size over multiple seasons, and multiple quantitative trait loci (QTLs) were observed. One QTL mapped to a region containing an Auxin Response Factor (ARF106). This gene is expressed during cell division and cell expansion stages, consistent with a potential role in the control of fruit size. The application of exogenous auxin to apples increased cell expansion, suggesting that endogenous auxin concentrations are at least one of the limiting factors controlling fruit size. The expression analysis of ARF106 linked to a strong QTL for fruit weight suggests that the auxin signal regulating fruit size could partially be modulated through the function of this gene. One class of gene (GH3) removes free auxin by conjugation to amino acids. The lower expression of these GH3 genes during rapid fruit expansion is consistent with the apple maximising auxin concentrations at this point.

  9. Biosynthesis of size-controlled gold nanoparticles using fungus, Penicillium sp.

    Science.gov (United States)

    Zhang, Xiaorong; He, Xiaoxiao; Wang, Kemin; Wang, Yonghong; Li, Huimin; Tan, Weihong

    2009-10-01

    The unique optoelectronic and physicochemical properties of gold nanoparticles are significantly dependent on the particle size, shape and structure. In this paper, biosynthesis of size-controlled gold nanoparticles using fungus Penicillium sp. is reported. Fungus Penicillium sp. could successfully bioreduce and nucleate AuCl4(-) ions, and lead to the assembly and formation of intracellular Au nanoparticles with spherical morphology and good monodispersity after exposure to HAuCl4 solution. Reaction temperature, as an important physiological parameter for fungus Penicillium sp. growth, could significantly control the size of the biosynthesized Au nanoparticles. The biological compositions and FTIR spectra analysis of fungus Penicillium sp. exposed to HAuCl4 solution indicated the intracellular reducing sugar played an important role in the occurrence of intracellular reduction of AuCl4(-) ions and the growth of gold nanoparticles. Furthermore, the intracellular gold nanoparticles could be easily separated from the fungal cell lysate by ultrasonication and centrifugation.

  10. Signalling and the control of skeletal muscle size

    International Nuclear Information System (INIS)

    Otto, Anthony; Patel, Ketan

    2010-01-01

    Skeletal muscle is highly adaptive to environmental stimuli and can alter its mass accordingly. This tissue is almost unique in that it can increase its size through two distinct mechanisms. It can grow through a cellular process mediated by cell fusion, or it can increase its size simply by increasing its protein content. Understanding how these processes are regulated is crucial for the development of potential therapies against debilitating skeletal muscle wasting diseases. Two key signalling molecules, Insulin like Growth Factor (IGF) and GDF-8/myostatin, have emerged in recent years to be potent regulators of skeletal muscle size. In this review we bring together recent data highlighting the important and novel aspects of both molecules and their signalling pathways, culminating in a discussion of the cellular and tissue phenotypic outcomes of their stimulation or antagonism. We emphasise the complex regulatory mechanisms and discuss the temporal and spatial differences that control their action, understanding of which is crucial to further their use as potential therapeutic targets.

  11. Signalling and the control of skeletal muscle size

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Anthony [School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights Campus, Reading, Berkshire, RG6 6UB (United Kingdom); Patel, Ketan, E-mail: ketan.patel@reading.ac.uk [School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights Campus, Reading, Berkshire, RG6 6UB (United Kingdom)

    2010-11-01

    Skeletal muscle is highly adaptive to environmental stimuli and can alter its mass accordingly. This tissue is almost unique in that it can increase its size through two distinct mechanisms. It can grow through a cellular process mediated by cell fusion, or it can increase its size simply by increasing its protein content. Understanding how these processes are regulated is crucial for the development of potential therapies against debilitating skeletal muscle wasting diseases. Two key signalling molecules, Insulin like Growth Factor (IGF) and GDF-8/myostatin, have emerged in recent years to be potent regulators of skeletal muscle size. In this review we bring together recent data highlighting the important and novel aspects of both molecules and their signalling pathways, culminating in a discussion of the cellular and tissue phenotypic outcomes of their stimulation or antagonism. We emphasise the complex regulatory mechanisms and discuss the temporal and spatial differences that control their action, understanding of which is crucial to further their use as potential therapeutic targets.

  12. Fe(II)-regulated moderate pre-oxidation of Microcystis aeruginosa and formation of size-controlled algae flocs for efficient flotation of algae cell and organic matter.

    Science.gov (United States)

    Qi, Jing; Lan, Huachun; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2018-06-15

    The coagulation/flocculation/flotation (C/F/F) process is becoming a popular method for algae-laden water treatment. However, the efficiency of flotation is highly dependent on the ability of the preceding coagulation/flocculation process to form flocculated algae flocs. This study aims to improve the Microcystis aeruginosa flotation efficiency from algae cell and organic matter aspects by applying Fe(II)-regulated pretreatment enhanced Al coagulation process. The ability of the C/F/F process to remove cyanobacterial cells can be enhanced from 8% to 99% at a Fe(II) dose of 30 μM. The Al dose needed can be reduced by more than half while achieving successful flotation. The introduced Fe(II) after KMnO 4 can not only realize moderate pre-oxidation of cyanobacterial cells, but also form in-situ Fe(III). The DOC value can also be decreased significantly due to the formation of in-situ Fe(III), which is more efficient in dissolved organic matter (DOM) removal compared with pre-formed Fe(III). In addition, the gradually hydrolyzed in-situ Fe(III) can facilitate the hydrolysis of Al as a dual-coagulant and promote the clustering and cross-linking of Al hydrolyzates, which can enhance the formation of size-controlled algae flocs. Finally, the size-controlled algae flocs can be effectively floated by the bubbles released in the flotation process due to the efficient collision and attachment between flocs and bubbles. Therefore, the efficient flotation of algae cell and organic matter can be realized by the Fe(II) regulated moderate pre-oxidation of M. aeruginosa and formation of size-controlled algae flocs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Stationary Size Distributions of Growing Cells with Binary and Multiple Cell Division

    Science.gov (United States)

    Rading, M. M.; Engel, T. A.; Lipowsky, R.; Valleriani, A.

    2011-10-01

    Populations of unicellular organisms that grow under constant environmental conditions are considered theoretically. The size distribution of these cells is calculated analytically, both for the usual process of binary division, in which one mother cell produces always two daughter cells, and for the more complex process of multiple division, in which one mother cell can produce 2 n daughter cells with n=1,2,3,… . The latter mode of division is inspired by the unicellular algae Chlamydomonas reinhardtii. The uniform response of the whole population to different environmental conditions is encoded in the individual rates of growth and division of the cells. The analytical treatment of the problem is based on size-dependent rules for cell growth and stochastic transition processes for cell division. The comparison between binary and multiple division shows that these different division processes lead to qualitatively different results for the size distribution and the population growth rates.

  14. Covariation of metabolic rates and cell size in coccolithophores

    Science.gov (United States)

    Aloisi, G.

    2015-08-01

    Coccolithophores are sensitive recorders of environmental change. The size of their coccosphere varies in the ocean along gradients of environmental conditions and provides a key for understanding the fate of this important phytoplankton group in the future ocean. But interpreting field changes in coccosphere size in terms of laboratory observations is hard, mainly because the marine signal reflects the response of multiple morphotypes to changes in a combination of environmental variables. In this paper I examine the large corpus of published laboratory experiments with coccolithophores looking for relations between environmental conditions, metabolic rates and cell size (a proxy for coccosphere size). I show that growth, photosynthesis and, to a lesser extent, calcification covary with cell size when pCO2, irradiance, temperature, nitrate, phosphate and iron conditions change. With the exception of phosphate and temperature, a change from limiting to non-limiting conditions always results in an increase in cell size. An increase in phosphate or temperature (below the optimum temperature for growth) produces the opposite effect. The magnitude of the coccosphere-size changes observed in the laboratory is comparable to that observed in the ocean. If the biological reasons behind the environment-metabolism-size link are understood, it will be possible to use coccosphere-size changes in the modern ocean and in marine sediments to investigate the fate of coccolithophores in the future ocean. This reasoning can be extended to the size of coccoliths if, as recent experiments are starting to show, coccolith size reacts to environmental change proportionally to coccosphere size. The coccolithophore database is strongly biased in favour of experiments with the coccolithophore Emiliania huxleyi (E. huxleyi; 82 % of database entries), and more experiments with other species are needed to understand whether these observations can be extended to coccolithophores in general. I

  15. Optical separation and controllable delivery of cells from particle and cell mixture

    Directory of Open Access Journals (Sweden)

    Li Yuchao

    2015-11-01

    Full Text Available Cell separation and delivery have recently gained significant attention in biological and biochemical studies. In thiswork, an optical method for separation and controllable delivery of cells by using an abruptly tapered fiber probe is reported. By launching a laser beam at the wavelength of 980 nm into the fiber, a mixture of cells with sizes of ~5 and ~3 μm and poly(methyl methacrylate particles with size of 5 μm are separated into three chains along the direction of propagation of light. The cell and particle chains are delivered in three dimensions over 600 μm distance. Experimental results are interpreted by numerical simulations. Optical forces and forward migration velocities of different particles and cells are calculated and discussed.

  16. Centrioles regulate centrosome size by controlling the rate of Cnn incorporation into the PCM.

    Science.gov (United States)

    Conduit, Paul T; Brunk, Kathrin; Dobbelaere, Jeroen; Dix, Carly I; Lucas, Eliana P; Raff, Jordan W

    2010-12-21

    centrosomes are major microtubule organizing centers in animal cells, and they comprise a pair of centrioles surrounded by an amorphous pericentriolar material (PCM). Centrosome size is tightly regulated during the cell cycle, and it has recently been shown that the two centrosomes in certain stem cells are often asymmetric in size. There is compelling evidence that centrioles influence centrosome size, but how centrosome size is set remains mysterious. we show that the conserved Drosophila PCM protein Cnn exhibits an unusual dynamic behavior, because Cnn molecules only incorporate into the PCM closest to the centrioles and then spread outward through the rest of the PCM. Cnn incorporation into the PCM is driven by an interaction with the conserved centriolar proteins Asl (Cep152 in humans) and DSpd-2 (Cep192 in humans). The rate of Cnn incorporation into the PCM is tightly regulated during the cell cycle, and this rate influences the amount of Cnn in the PCM, which in turn is an important determinant of overall centrosome size. Intriguingly, daughter centrioles in syncytial embryos only start to incorporate Cnn as they disengage from their mothers; this generates a centrosome size asymmetry, with mother centrioles always initially organizing more Cnn than their daughters. centrioles can control the amount of PCM they organize by regulating the rate of Cnn incorporation into the PCM. This mechanism can explain how centrosome size is regulated during the cell cycle and also allows mother and daughter centrioles to set centrosome size independently of one another.

  17. The Influences of Cell Type and ZnO Nanoparticle Size on Immune Cell Cytotoxicity and Cytokine Induction

    Directory of Open Access Journals (Sweden)

    Thurber Aaron

    2009-01-01

    Full Text Available Abstract Nanotechnology represents a new and enabling platform that promises to provide a range of innovative technologies for biological applications. ZnO nanoparticles of controlled size were synthesized, and their cytotoxicity toward different human immune cells evaluated. A differential cytotoxic response between human immune cell subsets was observed, with lymphocytes being the most resistant and monocytes being the most susceptible to ZnO nanoparticle-induced toxicity. Significant differences were also observed between previously activated memory lymphocytes and naive lymphocytes, indicating a relationship between cell-cycle potential and nanoparticle susceptibility. Mechanisms of toxicity involve the generation of reactive oxygen species, with monocytes displaying the highest levels, and the degree of cytotoxicity dependent on the extent of nanoparticle interactions with cellular membranes. An inverse relationship between nanoparticle size and cytotoxicity, as well as nanoparticle size and reactive oxygen species production was observed. In addition, ZnO nanoparticles induce the production of the proinflammatory cytokines, IFN-γ, TNF-α, and IL-12, at concentrations below those causing appreciable cell death. Collectively, these results underscore the need for careful evaluation of ZnO nanoparticle effects across a spectrum of relevant cell types when considering their use for potential new nanotechnology-based biological applications.

  18. Recovery of aging-related size increase of skin epithelial cells: in vivo mouse and in vitro human study.

    Directory of Open Access Journals (Sweden)

    Igor Sokolov

    Full Text Available The size increase of skin epithelial cells during aging is well-known. Here we demonstrate that treatment of aging cells with cytochalasin B substantially decreases cell size. This decrease was demonstrated on a mouse model and on human skin cells in vitro. Six nude mice were treated by topical application of cytochalasin B on skin of the dorsal left midsection for 140 days (the right side served as control for placebo treatment. An average decrease in cell size of 56±16% resulted. A reduction of cell size was also observed on primary human skin epithelial cells of different in vitro age (passages from 1 to 8. A cell strain obtained from a pool of 6 human subjects was treated with cytochalasin B in vitro for 12 hours. We observed a decrease in cell size that became statistically significant and reached 20-40% for cells of older passage (6-8 passages whereas no substantial change was observed for younger cells. These results may be important for understanding the aging processes, and for cosmetic treatment of aging skin.

  19. Sizing stack and battery of a fuel cell hybrid distribution truck

    OpenAIRE

    Tazelaar, E.; Shen, Y.; Veenhuizen, P.A.; Hofman, T.; Bosch, van den, P.P.J.

    2012-01-01

    An existing fuel cell hybrid distribution truck, built for demonstration purposes, is used as a case study to investigate the effect of stack (kW) and battery (kW, kWh) sizes on the hydrogen consumption of the vehicle. Three driving cycles, the NEDC for Low Power vehicles, CSC and JE05 cycle, define the driving requirements for the vehicle. The Equivalent Consumption Minimization Strategy (ECMS) is used for determining the control setpoint for the fuel cell and battery system. It closely appr...

  20. Film Grain-Size Related Long-Term Stability of Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Chiang, Chien-Hung; Wu, Chun-Guey

    2016-09-22

    The power conversion efficiency (PCE) of the perovskite solar cell is high enough to be commercially viable. The next important issue is the stability of the device. This article discusses the effect of the perovskite grain-size on the long-term stability of inverted perovskite solar cells. Perovskite films composed of various sizes of grains were prepared by controlling the solvent annealing time. The grain-size related stability of the inverted cells was investigated both in ambient atmosphere at relative humidity of approximately 30-40 % and in a nitrogen filled glove box (H 2 Operovskite film having the grain size larger than 1 μm (D-10) decreases less than 10 % with storage in a glove box and less than 15 % when it was stored under an ambient atmosphere for 30 days. However, the cell using the perovskite film composed of small (∼100 nm) perovskite grains (D-0) exhibits complete loss of PCE after storage under the ambient atmosphere for only 15 days and a PCE loss of up to 70 % with storage in the glove box for 30 days. These results suggest that, even under H 2 O-free conditions, the chemical- and thermal-induced production of pin holes at the grain boundaries of the perovskite film could be the reason for long-term instability of inverted perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Cell size and cell number in dwarf mutants of barley (Hordeum vulgare)

    International Nuclear Information System (INIS)

    Blonstein, A.D.; Gale, M.D.

    1984-01-01

    Sixteen height mutants, induced by sodium azide treatment of the two-rowed barley variety Proctor, have been used to investigate the relationship between the extent and nature of stem shortening with alterations in cell size and cell number, and the pleiotropic effects of dwarfing genes on vegetative development and agronomic performance. The studies on epidermal cell number and cell length in the developmentally earliest and latest elongated vegetative tissues - the coleoptile and peduncle resprectively - suggest that cell number may be the primary determinant of plant height. One semi-prostrate and one erectoides mutant are used to illustrate different cell number/cell size strategies and their relationships with gibberellin sensitivity, growth rate and lodging resistance are discussed. (author)

  2. Photoperiod-H1 (Ppd-H1) Controls Leaf Size1[OPEN

    Science.gov (United States)

    Digel, Benedikt; Tavakol, Elahe; Verderio, Gabriele; Xu, Xin

    2016-01-01

    Leaf size is a major determinant of plant photosynthetic activity and biomass; however, it is poorly understood how leaf size is genetically controlled in cereal crop plants like barley (Hordeum vulgare). We conducted a genome-wide association scan for flowering time, leaf width, and leaf length in a diverse panel of European winter cultivars grown in the field and genotyped with a single-nucleotide polymorphism array. The genome-wide association scan identified PHOTOPERIOD-H1 (Ppd-H1) as a candidate gene underlying the major quantitative trait loci for flowering time and leaf size in the barley population. Microscopic phenotyping of three independent introgression lines confirmed the effect of Ppd-H1 on leaf size. Differences in the duration of leaf growth and consequent variation in leaf cell number were responsible for the leaf size differences between the Ppd-H1 variants. The Ppd-H1-dependent induction of the BARLEY MADS BOX genes BM3 and BM8 in the leaf correlated with reductions in leaf size and leaf number. Our results indicate that leaf size is controlled by the Ppd-H1- and photoperiod-dependent progression of plant development. The coordination of leaf growth with flowering may be part of a reproductive strategy to optimize resource allocation to the developing inflorescences and seeds. PMID:27457126

  3. EPICS Controlled Collimator for Controlling Beam Sizes in HIPPO

    Energy Technology Data Exchange (ETDEWEB)

    Napolitano, Arthur Soriano [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Controlling the beam spot size and shape in a diffraction experiment determines the probed sample volume. The HIPPO - High-Pressure-Preferred Orientation– neutron time-offlight diffractometer is located at the Lujan Neutron Scattering Center in Los Alamos National Laboratories. HIPPO characterizes microstructural parameters, such as phase composition, strains, grain size, or texture, of bulk (cm-sized) samples. In the current setup, the beam spot has a 10 mm diameter. Using a collimator, consisting of two pairs of neutron absorbing boron-nitride slabs, horizontal and vertical dimensions of a rectangular beam spot can be defined. Using the HIPPO robotic sample changer for sample motion, the collimator would enable scanning of e.g. cylindrical samples along the cylinder axis by probing slices of such samples. The project presented here describes implementation of such a collimator, in particular the motion control software. We utilized the EPICS (Experimental Physics Interface and Control System) software interface to integrate the collimator control into the HIPPO instrument control system. Using EPICS, commands are sent to commercial stepper motors that move the beam windows.

  4. Control of cell proliferation, endoreduplication, cell size, and cell death by the retinoblastoma-related pathway in maize endosperm

    KAUST Repository

    Sabelli, Paolo A.; Liu, Yan; Dante, Ricardo Augusto; Lizarraga, Lucina E.; Nguyen, Hong N.; Brown, Sara W.; Klingler, John; Yu, Jingjuan; LaBrant, Evan; Layton, Tracy M.; Feldman, Max; Larkins, Brian A.

    2013-01-01

    , and programmed cell death. Although manipulation of these processes could maximize grain yield, how they are regulated and integrated is poorly understood. We show that the Retinoblastoma-related (RBR) pathway controls key aspects of endosperm development

  5. A New Size-based Platform for Circulating Tumor Cell Detection in Colorectal Cancer Patients.

    Science.gov (United States)

    Oh, Bo Young; Kim, Jhingook; Lee, Woo Yong; Kim, Hee Cheol

    2017-09-01

    Circulating tumor cells (CTCs) might play a significant role in cancer progression and metastasis. However, the ability to detect CTCs is limited, especially in cells undergoing epithelial-mesenchymal transition. In this study, we evaluated a new size-based CTC detection platform and its clinical efficacy in colorectal cancer. Blood samples were obtained from 76 patients with colorectal cancer and 20 healthy control subjects for CTC analysis. CTCs were enriched using a high-density microporous chip filter and were detected using a 4-color staining protocol including 4',6-diamidino-2-phenylindole (DAPI) for nucleated cells, CD45 monoclonal antibody (mAb) as a leukocyte marker, and epithelial cell adhesion molecule (EpCAM) mAb or cytokeratin (CK) mAb as an epithelial cell marker. CTC positivity was defined as DAPI-positive (DAPI + )/CD45 - /EpCAM + or CK + cells and clinical outcomes of patients were analyzed according to CTC counts. CTCs were detected in 50 patients using this size-based filtration platform. CTC + patients were more frequently identified with a high level of carcinoembryonic antigen and advanced stage cancer (P = .038 and P = .017, respectively). CTC counts for patients with stage IV cancer (12.47 ± 24.00) were significantly higher than those for patients with cancers that were stage I to III (2.84 ± 5.29; P = .005) and healthy control subjects (0.25 ± 0.55; P colorectal cancer patients. Our results suggest that this new size-based platform has potential for determining prognosis and therapeutic response in colorectal cancer patients. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Forces and dynamics in epithelial domes of controlled size and shape

    Science.gov (United States)

    Latorre-Ibars, Ernest; Casares, Laura; Gomez-Gonzalez, Manuel; Uroz, Marina; Arroyo, Marino; Trepat, Xavier

    Mechanobiology of epithelia plays a central role in morphogenesis, wound healing, and tumor progression. Its current understanding relies on mechanical measurements on flat epithelial layers. However, most epithelia in vivo exhibit a curved 3D shape enclosing a pressurized lumen. Using soft micropatterned substrates we produce massive parallel arrays of epithelial domes with controlled size and basal shape. We measure epithelial traction, tension, and luminal pressure in epithelial domes. The local stress tensor on the freestanding epithelial membrane is then mapped by combining measured luminal pressure and local curvature. We show that tension and cell shape are highly anisotropic and vary along the meridional position of the domes. Finally, we establish constitutive relations between shape, tension, and pressure during perturbations of the contractile machinery, osmotic shocks, and spontaneous fluctuations of dome volume. Our findings contradict a description of the epithelium as a fluid capillary surface. Cells in the dome are unable to relax into a uniform and isotropic tensional state through sub- and supra-cellular rearrangements. Mapping epithelial shape, tension, and pressure will enable quantitative studies of mechanobiology in 3D epithelia of controlled size and shape.

  7. Fundamental principles in bacterial physiology—history, recent progress, and the future with focus on cell size control: a review

    Science.gov (United States)

    Jun, Suckjoon; Si, Fangwei; Pugatch, Rami; Scott, Matthew

    2018-05-01

    Bacterial physiology is a branch of biology that aims to understand overarching principles of cellular reproduction. Many important issues in bacterial physiology are inherently quantitative, and major contributors to the field have often brought together tools and ways of thinking from multiple disciplines. This article presents a comprehensive overview of major ideas and approaches developed since the early 20th century for anyone who is interested in the fundamental problems in bacterial physiology. This article is divided into two parts. In the first part (sections 1–3), we review the first ‘golden era’ of bacterial physiology from the 1940s to early 1970s and provide a complete list of major references from that period. In the second part (sections 4–7), we explain how the pioneering work from the first golden era has influenced various rediscoveries of general quantitative principles and significant further development in modern bacterial physiology. Specifically, section 4 presents the history and current progress of the ‘adder’ principle of cell size homeostasis. Section 5 discusses the implications of coarse-graining the cellular protein composition, and how the coarse-grained proteome ‘sectors’ re-balance under different growth conditions. Section 6 focuses on physiological invariants, and explains how they are the key to understanding the coordination between growth and the cell cycle underlying cell size control in steady-state growth. Section 7 overviews how the temporal organization of all the internal processes enables balanced growth. In the final section 8, we conclude by discussing the remaining challenges for the future in the field.

  8. Multi-objective energy management optimization and parameter sizing for proton exchange membrane hybrid fuel cell vehicles

    International Nuclear Information System (INIS)

    Hu, Zunyan; Li, Jianqiu; Xu, Liangfei; Song, Ziyou; Fang, Chuan; Ouyang, Minggao; Dou, Guowei; Kou, Gaihong

    2016-01-01

    Highlights: • Fuel economy, lithium battery size and powertrain system durability are incorporated in optimization. • A multi-objective power allocation strategy by taking battery size into consideration is proposed. • Influences of battery capacity and auxiliary power on strategy design are explored. • Battery capacity and fuel cell service life for the system life cycle cost are optimized. - Abstract: The powertrain system of a typical proton electrolyte membrane hybrid fuel cell vehicle contains a lithium battery package and a fuel cell stack. A multi-objective optimization for this powertrain system of a passenger car, taking account of fuel economy and system durability, is discussed in this paper. Based on an analysis of the optimum results obtained by dynamic programming, a soft-run strategy was proposed for real-time and multi-objective control algorithm design. The soft-run strategy was optimized by taking lithium battery size into consideration, and implemented using two real-time algorithms. When compared with the optimized dynamic programming results, the power demand-based control method proved more suitable for powertrain systems equipped with larger capacity batteries, while the state of charge based control method proved superior in other cases. On this basis, the life cycle cost was optimized by considering both lithium battery size and equivalent hydrogen consumption. The battery capacity selection proved more flexible, when powertrain systems are equipped with larger capacity batteries. Finally, the algorithm has been validated in a fuel cell city bus. It gets a good balance of fuel economy and system durability in a three months demonstration operation.

  9. The evolution of bacterial cell size: the internal diffusion-constraint hypothesis.

    Science.gov (United States)

    Gallet, Romain; Violle, Cyrille; Fromin, Nathalie; Jabbour-Zahab, Roula; Enquist, Brian J; Lenormand, Thomas

    2017-07-01

    Size is one of the most important biological traits influencing organismal ecology and evolution. However, we know little about the drivers of body size evolution in unicellulars. A long-term evolution experiment (Lenski's LTEE) in which Escherichia coli adapts to a simple glucose medium has shown that not only the growth rate and the fitness of the bacterium increase over time but also its cell size. This increase in size contradicts prominent 'external diffusion' theory (EDC) predicting that cell size should have evolved toward smaller cells. Among several scenarios, we propose and test an alternative 'internal diffusion-constraint' (IDC) hypothesis for cell size evolution. A change in cell volume affects metabolite concentrations in the cytoplasm. The IDC states that a higher metabolism can be achieved by a reduction in the molecular traffic time inside of the cell, by increasing its volume. To test this hypothesis, we studied a population from the LTEE. We show that bigger cells with greater growth and CO 2 production rates and lower mass-to-volume ratio were selected over time in the LTEE. These results are consistent with the IDC hypothesis. This novel hypothesis offers a promising approach for understanding the evolutionary constraints on cell size.

  10. Asymmetries in Cell Division, Cell Size, and Furrowing in the Xenopus laevis Embryo.

    Science.gov (United States)

    Tassan, Jean-Pierre; Wühr, Martin; Hatte, Guillaume; Kubiak, Jacek

    2017-01-01

    Asymmetric cell divisions produce two daughter cells with distinct fate. During embryogenesis, this mechanism is fundamental to build tissues and organs because it generates cell diversity. In adults, it remains crucial to maintain stem cells. The enthusiasm for asymmetric cell division is not only motivated by the beauty of the mechanism and the fundamental questions it raises, but has also very pragmatic reasons. Indeed, misregulation of asymmetric cell divisions is believed to have dramatic consequences potentially leading to pathogenesis such as cancers. In diverse model organisms, asymmetric cell divisions result in two daughter cells, which differ not only by their fate but also in size. This is the case for the early Xenopus laevis embryo, in which the two first embryonic divisions are perpendicular to each other and generate two pairs of blastomeres, which usually differ in size: one pair of blastomeres is smaller than the other. Small blastomeres will produce embryonic dorsal structures, whereas the larger pair will evolve into ventral structures. Here, we present a speculative model on the origin of the asymmetry of this cell division in the Xenopus embryo. We also discuss the apparently coincident asymmetric distribution of cell fate determinants and cell-size asymmetry of the 4-cell stage embryo. Finally, we discuss the asymmetric furrowing during epithelial cell cytokinesis occurring later during Xenopus laevis embryo development.

  11. Differentiation of low- and high-grade clear cell renal cell carcinoma: Tumor size versus CT perfusion parameters.

    Science.gov (United States)

    Chen, Chao; Kang, Qinqin; Xu, Bing; Guo, Hairuo; Wei, Qiang; Wang, Tiegong; Ye, Hui; Wu, Xinhuai

    To compare the utility of tumor size and CT perfusion parameters for differentiation of low- and high-grade clear cell renal cell carcinoma (RCC). Tumor size, Equivalent blood volume (Equiv BV), permeability surface-area product (PS), blood flow (BF), and Fuhrman pathological grading of clear cell RCC were retrospectively analyzed. High-grade clear cell RCC had significantly higher tumor size and lower PS than low grade. Tumor size positively correlated with Fuhrman grade, but PS negatively did. Tumor size and PS were significantly independent indexes for differentiating high-grade from low-grade clear cell RCC. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Effects of Microbubble Size on Ultrasound-Mediated Gene Transfection in Auditory Cells

    Directory of Open Access Journals (Sweden)

    Ai-Ho Liao

    2014-01-01

    Full Text Available Gene therapy for sensorineural hearing loss has recently been used to insert genes encoding functional proteins to preserve, protect, or even regenerate hair cells in the inner ear. Our previous study demonstrated a microbubble- (MB-facilitated ultrasound (US technique for delivering therapeutic medication to the inner ear. The present study investigated whether MB-US techniques help to enhance the efficiency of gene transfection by means of cationic liposomes on HEI-OC1 auditory cells and whether MBs of different sizes affect such efficiency. Our results demonstrated that the size of MBs was proportional to the concentration of albumin or dextrose. At a constant US power density, using 0.66, 1.32, and 2.83 μm albumin-shelled MBs increased the transfection rate as compared to the control by 30.6%, 54.1%, and 84.7%, respectively; likewise, using 1.39, 2.12, and 3.47 μm albumin-dextrose-shelled MBs increased the transfection rates by 15.9%, 34.3%, and 82.7%, respectively. The results indicate that MB-US is an effective technique to facilitate gene transfer on auditory cells in vitro. Such size-dependent MB oscillation behavior in the presence of US plays a role in enhancing gene transfer, and by manipulating the concentration of albumin or dextrose, MBs of different sizes can be produced.

  13. The Adder Phenomenon Emerges from Independent Control of Pre- and Post-Start Phases of the Budding Yeast Cell Cycle.

    Science.gov (United States)

    Chandler-Brown, Devon; Schmoller, Kurt M; Winetraub, Yonatan; Skotheim, Jan M

    2017-09-25

    Although it has long been clear that cells actively regulate their size, the molecular mechanisms underlying this regulation have remained poorly understood. In budding yeast, cell size primarily modulates the duration of the cell-division cycle by controlling the G1/S transition known as Start. We have recently shown that the rate of progression through Start increases with cell size, because cell growth dilutes the cell-cycle inhibitor Whi5 in G1. Recent phenomenological studies in yeast and bacteria have shown that these cells add an approximately constant volume during each complete cell cycle, independent of their size at birth. These results seem to be in conflict, as the phenomenological studies suggest that cells measure the amount they grow, rather than their size, and that size control acts over the whole cell cycle, rather than specifically in G1. Here, we propose an integrated model that unifies the adder phenomenology with the molecular mechanism of G1/S cell-size control. We use single-cell microscopy to parameterize a full cell-cycle model based on independent control of pre- and post-Start cell-cycle periods. We find that our model predicts the size-independent amount of cell growth during the full cell cycle. This suggests that the adder phenomenon is an emergent property of the independent regulation of pre- and post-Start cell-cycle periods rather than the consequence of an underlying molecular mechanism measuring a fixed amount of growth. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Controlling cell volume for efficient PHB production by Halomonas.

    Science.gov (United States)

    Jiang, Xiao-Ran; Yao, Zhi-Hao; Chen, Guo-Qiang

    2017-11-01

    Bacterial morphology is decided by cytoskeleton protein MreB and cell division protein FtsZ encoded by essential genes mreB and ftsZ, respectively. Inactivating mreB and ftsZ lead to increasing cell sizes and cell lengths, respectively, yet seriously reduce cell growth ability. Here we develop a temperature-responsible plasmid expression system for compensated expression of relevant gene(s) in mreB or ftsZ disrupted recombinants H. campaniensis LS21, allowing mreB or ftsZ disrupted recombinants to grow normally at 30°C in a bioreactor for 12h so that a certain cell density can be reached, followed by 36h cell size expansions or cell shape elongations at elevated 37°C at which the mreB and ftsZ encoded plasmid pTKmf failed to replicate in the recombinants and thus lost themselves. Finally, 80% PHB yield increase was achieved via controllable morphology manipulated H. campaniensis LS21. It is concluded that controllable expanding cell volumes (widths or lengths) provides more spaces for accumulating more inclusion body polyhydroxybutyrate (PHB) and the resulting cell gravity precipitation benefits the final separation of cells and product during downstream. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  15. FGFR3 regulates brain size by controlling progenitor cell proliferation and apoptosis during embryonic development.

    Science.gov (United States)

    Inglis-Broadgate, Suzanne L; Thomson, Rachel E; Pellicano, Francesca; Tartaglia, Michael A; Pontikis, Charlie C; Cooper, Jonathan D; Iwata, Tomoko

    2005-03-01

    Mice with the K644E kinase domain mutation in fibroblast growth factor receptor 3 (Fgfr3) (EIIa;Fgfr3(+/K644E)) exhibited a marked enlargement of the brain. The brain size was increased as early as E11.5, not secondary to the possible effect of Fgfr3 activity in the skeleton. Furthermore, the mutant brains showed a dramatic increase in cortical thickness, a phenotype opposite to that in FGF2 knockout mice. Despite this increased thickness, cortical layer formation was largely unaffected and no cortical folding was observed during embryonic days 11.5-18.5 (E11.5-E18.5). Measurement of cortical thickness revealed an increase of 38.1% in the EIIa;Fgfr3(+/K644E) mice at E14.5 and the advanced appearance of the cortical plate was frequently observed at this stage. Unbiased stereological analysis revealed that the volume of the ventricular zone (VZ) was increased by more than two fold in the EIIa;Fgfr3(+/K644E) mutants at E14.5. A relatively mild increase in progenitor cell proliferation and a profound decrease in developmental apoptosis during E11.5-E14.5 most likely accounts for the dramatic increase in total telecephalic cell number. Taken together, our data suggest a novel function of Fgfr3 in controlling the development of the cortex, by regulating proliferation and apoptosis of cortical progenitors.

  16. Size-amplified acoustofluidic separation of circulating tumor cells with removable microbeads

    Science.gov (United States)

    Liu, Huiqin; Ao, Zheng; Cai, Bo; Shu, Xi; Chen, Keke; Rao, Lang; Luo, Changliang; Wang, Fu-Bin; Liu, Wei; Bondesson, Maria; Guo, Shishang; Guo, Feng

    2018-06-01

    Isolation and analysis of rare circulating tumor cells (CTCs) is of great interest in cancer diagnosis, prognosis, and treatment efficacy evaluation. Acoustofluidic cell separation becomes an attractive method due to its contactless, noninvasive, simple, and versatile features. However, the indistinctive physical difference between CTCs and normal blood cells limits the purity of CTCs using current acoustic methods. Herein, we demonstrate a size-amplified acoustic separation and release of CTCs with removable microbeads. CTCs selectively bound to size-amplifiers (40 μm-diameter anti-EpCAM/gelatin-coated SiO2 microbeads) have significant physical differences (size and mechanics) compared to normal blood cells, resulting in an amplification of acoustic radiation force approximately a hundredfold over that of bare CTCs or normal blood cells. Therefore, CTCs can be efficiently sorted out with size-amplifiers in a traveling surface acoustic wave microfluidic device and released from size-amplifiers by enzymatic degradation for further purification or downstream analysis. We demonstrate a cell separation from blood samples with a total efficiency (E total) of ∼ 77%, purity (P) of ∼ 96%, and viability (V) of ∼83% after releasing cells from size-amplifiers. Our method substantially improves the emerging application of rare cell purification for translational medicine.

  17. [Influence of slot size on torque control].

    Science.gov (United States)

    Tian, Jun; Liu, Zhong-Hao; Zhang, Ding; Wu, Chuan-Jun

    2009-12-01

    To study the influence of two slot size brackets on torque control when teeth interacted in the same arch. After the upper arch was aligned and leveled in Typodont study, the inclinations of upper teeth 5 +/- 5 were measured when 0.457 2 mm x 0.635 0 mm OPA-K brackets and 0.558 8 mmx0.711 2 mm OPA-K brackets were filled with 0.431 8 mm x 0.635 0 mm stainless steel wire. This experiment was duplicated 10 times. The inclin of each tooth were transformed to the absolute values of the torque play angle psi by computing program, and paired-t test was used. The two kinds of slot size brackets were different with statistical significance on torque control. When the brackets were filled with 0.431 8 mm x 0.635 0 mm stainless steel wire, the absolute values of the angle psi in 0.558 8 mm x 0.711 2 mm and 0.457 2 mm x 0.635 0 mm slot size brackets were 6.140 degrees +/- 3.758 degrees and 2.608 degrees +/- 1.479 degrees respectively, and the average difference of that between the two slot size brackets was 3.532 degrees. The absolute values of the angle psi in the upper left and right canine brackets were 2.560 degrees +/- 2.605 degrees, 4.230 degrees +/- 2.817 degrees, 1.260 degrees +/- 0.747 degrees and 2.070 degrees +/- 0.663 degrees respectively, and average differences between them were smaller than that in the other teeth. There was difference between the two kinds of slot size brackets on torque control, and 0.457 2 mm x 0.635 0 mm slot size bracket controls torque better when filled with the same size wire. In this study, the teeth interaction in the same arch probably caused the result that the difference of two slot size brackets on torque control was less than the study results of the theory calculations and material studys before.

  18. Phospholipid-assisted synthesis of size-controlled gold nanoparticles

    International Nuclear Information System (INIS)

    He Peng; Zhu Xinyuan

    2007-01-01

    Morphology and size control of gold nanoparticles (AuNPs) by phospholipids (PLs) has been reported. It was found that gold entities could form nanostructures with different sizes controlled by PLs in an aqueous solution. During the preparation of 1.5 nm gold seeds, AuNPs were obtained from the reduction of gold complex by sodium borohydride and capped by citrate for stabilization. With the different ratios between seed solution and growth solution, which was composed by gold complex and PLs, gold seeds grew into larger nanoparticles step by step until enough large size up to 30 nm. The main discovery of this work is that common biomolecules, such as PLs can be used to control nanoparticle size. This conclusion has been confirmed by transmission electron micrographs, particle size analysis, and UV-vis spectra

  19. Chemical-Reaction-Controlled Phase Separated Drops: Formation, Size Selection, and Coarsening

    Science.gov (United States)

    Wurtz, Jean David; Lee, Chiu Fan

    2018-02-01

    Phase separation under nonequilibrium conditions is exploited by biological cells to organize their cytoplasm but remains poorly understood as a physical phenomenon. Here, we study a ternary fluid model in which phase-separating molecules can be converted into soluble molecules, and vice versa, via chemical reactions. We elucidate using analytical and simulation methods how drop size, formation, and coarsening can be controlled by the chemical reaction rates, and categorize the qualitative behavior of the system into distinct regimes. Ostwald ripening arrest occurs above critical reaction rates, demonstrating that this transition belongs entirely to the nonequilibrium regime. Our model is a minimal representation of the cell cytoplasm.

  20. Size Matters, if You Control Your Junk

    DEFF Research Database (Denmark)

    Asness, Clifford S.; Frazzini, Andrea; Israel, Ronen

    that do not rely on market prices, is weak internationally, and is subsumed by proxies for illiquidity. We find, however, that these challenges are dismantled when controlling for the quality, or the inverse "junk", of a firm. A significant size premium emerges, which is stable through time, robust...... to the specification, more consistent across seasons and markets, not concentrated in microcaps, robust to non-price based measures of size, and not captured by an illiquidity premium. Controlling for quality/junk also explains interactions between size and other return characteristics such as value and momentum.......The size premium has been challenged along many fronts: it has a weak historical record, varies significantly over time, in particular weakening after its discovery in the early 1980s, is concentrated among microcap stocks, predominantly resides in January, is not present for measures of size...

  1. Release Properties and Cellular Uptake in Caco-2 Cells of Size-Controlled Chitosan Nanoparticles.

    Science.gov (United States)

    Je, Hyun Jeong; Kim, Eun Suh; Lee, Ji-Soo; Lee, Hyeon Gyu

    2017-12-20

    The influences of particle size on the physicochemical, release, and cellular uptake properties of chitosan nanoparticles (CSNPs) were investigated. Ionotropic CSNPs of different sizes (200-1000 nm) loaded with two model core materials (resveratrol or coumarin-6) were prepared using tripolyphosphate and carrageenan as cross-linkers. With an increase of particle size, zeta potential (34.6 ± 0.5 to 51.1 ± 0.9) and entrapment efficiency (14.9 ± 1.4 to 40.9 ± 1.9) of the CSNPs were significantly (p cellular uptake of CSNPs were significantly increased from 3.70 ± 0.03 to 5.24 ± 0.20 with an increase of particle size from 200 to 600 nm, whereas those significantly decreased from 5.24 ± 0.20 to 4.55 ± 0.2 for particles larger than 600 nm in transwell assay. Moreover, much the same uptake patterns were also observed in confocal microscopy and flow cytometry. Investigation of cellular uptake of CSNPs revealed positive correlations between ZP and EE and indicated the effects of complex factors of nanoparticles other than size. These results provide a better understanding of CSNPs absorption and raises the possibility of controlling alternative nanoparticle properties to enhance bioavailability.

  2. Graphene-Based Flexible Micrometer-Sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.; Qaisi, Ramy M.; Hussain, Muhammad Mustafa

    2013-01-01

    Microbial fuel cells harvest electrical energy produced by bacteria during the natural decomposition of organic matter. We report a micrometer-sized microbial fuel cell that is able to generate nanowatt-scale power from microliters of liquids

  3. Size-controlled soft-template synthesis of carbon nanodots toward versatile photoactive materials.

    Science.gov (United States)

    Kwon, Woosung; Lee, Gyeongjin; Do, Sungan; Joo, Taiha; Rhee, Shi-Woo

    2014-02-12

    Size-controlled soft-template synthesis of carbon nanodots (CNDs) as novel photoactive materials is reported. The size of the CNDs can be controlled by regulating the amount of an emulsifier. As the size increases, the CNDs exhibit blue-shifted photoluminescence (PL) or so-called an inverse PL shift. Using time-correlated single photon counting, ultraviolet photoelectron spectroscopy, and low-temperature PL measurements, it is revealed that the CNDs are composed of sp² clusters with certain energy gaps and their oleylamine ligands act as auxochromes to reduce the energy gaps. This insight can provide a plausible explanation on the origin of the inverse PL shift which has been debatable over a past decade. To explore the potential of the CNDs as photoactive materials, several prototypes of CND-based optoelectronic devices, including multicolored light-emitting diodes and air-stable organic solar cells, are demonstrated. This study could shed light on future applications of the CNDs and further expedite the development of other related fields. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. High-efficiency single cell encapsulation and size selective capture of cells in picoliter droplets based on hydrodynamic micro-vortices.

    Science.gov (United States)

    Kamalakshakurup, Gopakumar; Lee, Abraham P

    2017-12-05

    Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of the primary challenges for droplet based single cell assays is single cell encapsulation in droplets, currently achieved either randomly, dictated by Poisson statistics, or by hydrodynamic techniques. In this paper, we present an interfacial hydrodynamic technique which initially traps the cells in micro-vortices, and later releases them one-to-one into the droplets, controlled by the width of the outer streamline that separates the vortex from the flow through the streaming passage adjacent to the aqueous-oil interface (d gap ). One-to-one encapsulation is achieved at a d gap equal to the radius of the cell, whereas complete trapping of the cells is realized at a d gap smaller than the radius of the cell. The unique feature of this technique is that it can perform 1. high efficiency single cell encapsulations and 2. size-selective capturing of cells, at low cell loading densities. Here we demonstrate these two capabilities with a 50% single cell encapsulation efficiency and size selective separation of platelets, RBCs and WBCs from a 10× diluted blood sample (WBC capture efficiency at 70%). The results suggest a passive, hydrodynamic micro-vortex based technique capable of performing high-efficiency single cell encapsulation for cell based assays.

  5. SHOEBOX Modulates Root Meristem Size in Rice through Dose-Dependent Effects of Gibberellins on Cell Elongation and Proliferation.

    Science.gov (United States)

    Li, Jintao; Zhao, Yu; Chu, Huangwei; Wang, Likai; Fu, Yanru; Liu, Ping; Upadhyaya, Narayana; Chen, Chunli; Mou, Tongmin; Feng, Yuqi; Kumar, Prakash; Xu, Jian

    2015-08-01

    Little is known about how the size of meristem cells is regulated and whether it participates in the control of meristem size in plants. Here, we report our findings on shoebox (shb), a mild gibberellin (GA) deficient rice mutant that has a short root meristem size. Quantitative analysis of cortical cell length and number indicates that shb has shorter, rather than fewer, cells in the root meristem until around the fifth day after sowing, from which the number of cortical cells is also reduced. These defects can be either corrected by exogenous application of bioactive GA or induced in wild-type roots by a dose-dependent inhibitory effect of paclobutrazol on GA biosynthesis, suggesting that GA deficiency is the primary cause of shb mutant phenotypes. SHB encodes an AP2/ERF transcription factor that directly activates transcription of the GA biosynthesis gene KS1. Thus, root meristem size in rice is modulated by SHB-mediated GA biosynthesis that regulates the elongation and proliferation of meristem cells in a developmental stage-specific manner.

  6. SHOEBOX Modulates Root Meristem Size in Rice through Dose-Dependent Effects of Gibberellins on Cell Elongation and Proliferation.

    Directory of Open Access Journals (Sweden)

    Jintao Li

    2015-08-01

    Full Text Available Little is known about how the size of meristem cells is regulated and whether it participates in the control of meristem size in plants. Here, we report our findings on shoebox (shb, a mild gibberellin (GA deficient rice mutant that has a short root meristem size. Quantitative analysis of cortical cell length and number indicates that shb has shorter, rather than fewer, cells in the root meristem until around the fifth day after sowing, from which the number of cortical cells is also reduced. These defects can be either corrected by exogenous application of bioactive GA or induced in wild-type roots by a dose-dependent inhibitory effect of paclobutrazol on GA biosynthesis, suggesting that GA deficiency is the primary cause of shb mutant phenotypes. SHB encodes an AP2/ERF transcription factor that directly activates transcription of the GA biosynthesis gene KS1. Thus, root meristem size in rice is modulated by SHB-mediated GA biosynthesis that regulates the elongation and proliferation of meristem cells in a developmental stage-specific manner.

  7. Cell Size Breathing and Possibilities to Introduce Cell Sleep Mode

    DEFF Research Database (Denmark)

    Micallef, Gilbert; Mogensen, Preben; Scheck, Hans-Otto

    2010-01-01

    regular upgrades in the infrastructure. While network equipment is in itself becoming more efficient, these upgrades still increase the overall energy consumption of the networks. This paper investigates the energy saving potential of exploiting cell size breathing by putting low loaded cells into sleep...... mode. The energy consumption and network performance of the resulting network are used to quantify the potential of this feature. The investigation is carried out on a tilt optimized network. Since putting cells into sleep mode results in a non-optimum antenna tilt configuration, this paper also...

  8. Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles

    Science.gov (United States)

    Huber, Dale L [Albuquerque, NM

    2011-07-05

    A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

  9. Graphene interfaced perovskite solar cells: Role of graphene flake size

    Science.gov (United States)

    Sakorikar, Tushar; Kavitha, M. K.; Tong, Shi Wun; Vayalamkuzhi, Pramitha; Loh, Kian Ping; Jaiswal, Manu

    2018-04-01

    Graphene interfaced inverted planar heterojunction perovskite solar cells are fabricated by facile solution method and studied its potential as hole conducting layer. Reduced graphene oxide (rGO) with small and large flake size and Polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) are utilized as hole conducting layers in different devices. For the solar cell employing PEDOT:PSS as hole conducting layer, 3.8 % photoconversion efficiency is achieved. In case of solar cells fabricated with rGO as hole conducting layer, the efficiency of the device is strongly dependent on flake size. With all other fabrication conditions kept constant, the efficiency of graphene-interfaced solar cell improves by a factor of 6, by changing the flake size of graphene oxide. We attribute this effect to uniform coverage of graphene layer and improved electrical percolation network.

  10. Fabrication and size control of Ag nano particles

    International Nuclear Information System (INIS)

    Farbod, M.; Batvandi, M. R.

    2012-01-01

    The objective of this research was to fabricate Ag nanoparticles and control their sizes. Colloidal Ag nanoparticles with particle size of 30 nm were prepared by dissolving AgNO 3 in ethanol and through the chemical reduction of Ag + in alcohol solution. To control the nanoparticle size, different samples were fabricated by changing the AgNO 3 and stabilizer concentrations and the effects of different factors on the shape and size of nanoparticles were investigated. The samples were characterized using Scanning Electron Microscopy and EDX analysis. The results showed that by increasing the AgNO 3 concentration, the average size of nanoparticles increases and nanoparticles lose their spherical shape. Also, we found that by using the stabilizer, it is possible to produce stable nanoparticles but increasing the stabilizer concentration caused an increase in size of nanoparticles. Fabrication of nanoparticles without using stabilizer was achieved but the results showed the nanoparticles size had a growth of 125 nm/h in the alcoholic media.

  11. Dose dependency of the frequency of micronucleated binucleated clone cells and of division related median clone sizes difference. Pt. 2

    International Nuclear Information System (INIS)

    Hagemann, G,; Kreczik, A.; Treichel, M.

    1996-01-01

    Following irradiation of the progenitor cells the clone growth of CHO cells decreases as a result of cell losses. Lethally acting expressions of micronuclei are produced by heritable lethal mutations. The dependency of the frequency of micronucleated binucleated clone cells and of the median clone sizes difference on the radiation dose was measured and compared to non-irradiated controls. Using the cytokinesis-block-micronucleus-method binucleated cells with micronuclei were counted as ratio of all binucleated cells within a clone size distribution. This ratio (shortened: micronucleus yield) was determined for all clone size distributions, which had been exposed to different irradiation doses and incubation times. The micronucleus yields were compared to the corresponding median clone sizes differences. The micronucleus yield is linearly dependent on the dose and is independent of the incubation time. The same holds true for the division related median clone sizes difference, which as a result is also linearly dependent on the micronucleus yield. Due to the inevitably errors of the cell count of micronucleated binucleated cells, an automatic measurement of the median clone sizes differences is the preferred method for evaluation of cellular radiation sensitivity for heritable lethal mutations. This value should always be determined in addition, if clone survival fractions are used as predictive test because it allows for an estimation of the remission probability of surviving cells. (orig.) [de

  12. Scalable preparation of sized-controlled Co-N-C electrocatalyst for efficient oxygen reduction reaction

    Science.gov (United States)

    Ai, Kelong; Li, Zelun; Cui, Xiaoqiang

    2017-11-01

    Heat-treated metal-nitrogen-carbon (M-N-C) materials are emerging as promising non-precious catalysts to replace expensive Pt-based materials for oxygen reduction reaction (ORR) in energy conversion and storage devices. Despite recent progress, their activity and durability are still far from satisfactory. The activity site and particle size are among the most important factors for the ORR activity of M-N-C catalysts. Extensive efforts have been made to reveal the correlation of active site and activity. However, it remains unclear to what extent the particle size will influence the ORR activity of M-N-C materials. Moreover, to the best of our knowledge, controllable synthesis of M-N-C catalysts with high-density activity sites remains elusive. Herein, we develop a straightforward method to produce a monodisperse and size-controlled Co-N-C (Nano-P-ZIF-67) electrocatalyst, and systemically investigate its catalytic mechanisms. Only by optimizing the particle size, Nano-P-ZIF-67 outperforms the commercial 20 wt% Pt/C regarding all evaluating indicators for ORR catalysts in alkaline media including higher catalytic activity, durability, and stronger methanol tolerance. Nano-P-ZIF-67 is assembled into a cell, and the cell shows a power density of 45.5 mW/cm2, which is the highest value among currently studied cathode catalysts. We expect Nano-P-ZIF-67 to be a highly interesting candidate for the next generation of ORR catalysts.

  13. Heterotrophic free-living and particle-bound bacterial cell size in the ...

    Indian Academy of Sciences (India)

    PRAKASH

    the heterotrophic bacterial cell size in the various water bodies studied in this investigation. The possible ... seasonal changes in abundance and cell size of heterotrophic ... data, 1995) physiological stress indicated by the presence of small ...

  14. Sample size calculations for case-control studies

    Science.gov (United States)

    This R package can be used to calculate the required samples size for unconditional multivariate analyses of unmatched case-control studies. The sample sizes are for a scalar exposure effect, such as binary, ordinal or continuous exposures. The sample sizes can also be computed for scalar interaction effects. The analyses account for the effects of potential confounder variables that are also included in the multivariate logistic model.

  15. Particle size control of detergents in mixed flow spray dryers

    Directory of Open Access Journals (Sweden)

    Mark Jonathan Crosby

    2015-03-01

    Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

  16. Regional variations in HDL metabolism in human fat cells: effect of cell size

    International Nuclear Information System (INIS)

    Despres, J.; Fong, B.S.; Julien, P.; Jimenez, J.; Angel, A.

    1987-01-01

    Abdominal obesity is related to reduced plasma high-density lipoprotein (HDL) cholesterol, and both are associated with cardiovascular disease risk. The authors have observed that plasma membranes from abdominal subcutaneous adipocytes have a greater HDL binding capacity than omental fat cell plasma membranes. The present study examined whether these binding characteristics could be due to differences in fat cell size or cholesterol concentration between the two adipose depots. Abdominal subcutaneous and deep omental fat were obtained from massively obese patients at surgery. Subcutaneous abdominal fat cells were significantly larger and their cellular cholesterol content greater than omental adipocytes. The uptake of HDL by collagenase-isolated fat cells was studied by incubating the cells for 2 h at 37 0 C with 10 μg/ml 125 I-HDL 2 or 125 I-HDL 3 . In both depots, the cellular uptake of 125 I-HDL 2 and 125 I-HDL 3 was specifically inhibited by addition of 25-fold excess unlabeled HDL and a close correlation was observed between the cellular uptake of 125 I-HDL 2 and 125 I-HDL 3 . In obese patients, the uptake of 125 I-HDL was higher in subcutaneous cells than in omental cells. The cellular 125 I-HDL uptake was significantly correlated with adipocyte size and fat cell cholesterol content but not with adipocyte cholesterol concentration. These results suggest that the higher HDL uptake observed in subcutaneous cells compared with omental cells in obesity is the result of differences in adipocyte size rather than differences in the cholesterol concentration (cholesterol-to-triglyceride ratio). The increased interaction of HDL with hypertrophied abdominal adipocytes may play an important role in determining the lipid composition of HDL in obesity

  17. Environment friendly approach for size controllable synthesis of biocompatible Silver nanoparticles using diastase.

    Science.gov (United States)

    Maddinedi, Sireesh Babu; Mandal, Badal Kumar; Anna, Kiran Kumar

    2017-01-01

    A green, facile method for the size selective synthesis of silver nanoparticles (AgNPs) using diastase as green reducing and stabilizing agent is reported. The thiol groups present in the diastase are mainly responsible for the rapid reaction rate of silver nanoparticles synthesis. The variation in the size and morphology of AgNPs were studied by changing the pH of diastase. The prepared silver nanoparticles were characterized by using UV-vis, XRD, FTIR, TEM and SAED. The FTIR analysis revealed the stabilization of diastase molecules on the surface of AgNPs. Additionally, in-vitro cytotoxicity experiments concluded that the cytotoxicity of the as-synthesized AgNPs towards mouse fibroblast (3T3) cell lines is dose and size dependent. Furthermore, the present method is an alternative to the traditional chemical methods of size controlled AgNPs synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Precise Morphology Control and Continuous Fabrication of Perovskite Solar Cells Using Droplet-Controllable Electrospray Coating System.

    Science.gov (United States)

    Hong, Seung Chan; Lee, Gunhee; Ha, Kyungyeon; Yoon, Jungjin; Ahn, Namyoung; Cho, Woohyung; Park, Mincheol; Choi, Mansoo

    2017-03-08

    Herein, we developed a novel electrospray coating system for continuous fabrication of perovskite solar cells with high performance. Our system can systemically control the size of CH 3 NH 3 PbI 3 precursor droplets by modulating the applied electrical potential, shown to be a crucial factor for the formation of perovskite films. As a result, we have obtained pinhole-free and large grain-sized perovskite solar cells, yielding the best PCE of 13.27% with little photocurrent hysteresis. Furthermore, the average PCE through the continuous coating process was 11.56 ± 0.52%. Our system demonstrates not only the high reproducibility but also a new way to commercialize high-quality perovskite solar cells.

  19. Nuclear size and cell division delay

    International Nuclear Information System (INIS)

    Bird, R.P.

    1986-01-01

    Radiation-induced division delay has been linked to damage at the nuclear envelope. Further, cells in G 2 phase are drastically arrested by high LET radiation such that single particles traversing cell nuclei may produce measurable division delay. A modest effort was initiated using two related cell lines of different size, near-diploid cells and near-tetraploid cells of Chinese hamster origin, to compare their sensitivity for radiation-induced division delay. If the nuclear surface is the critical target, then a larger nuclear cross-section presented to an alpha-particle beam should exhibit delay induced by a lesser particle fluence. Preliminary estimates of the extent of delay in asynchronous cultures following low doses of gamma-irradiation or of alpha-irradiation were made by in-situ observation of the time of onset of mitosis and by fixation and staining of cultures to determine the mitotic index as a function of time after irradiation. The basic approach to evaluating division delay will be to use Colecemid to accumulate mitotic cells over a period of time

  20. Rock sampling. [method for controlling particle size distribution

    Science.gov (United States)

    Blum, P. (Inventor)

    1971-01-01

    A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

  1. Changes in the number and size of nucleoli of Chara vulgaris L. antheridial filament cells during the period preceding light-induced re-initiation of cell divisions following a mitodepressive effect of darkness

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-01-01

    Full Text Available The changes in number and size of nucleoli of Chara vulgaris antheridial filament cells were monitored with the use of Howell and Black's silver staining method. After a 3-day mitodepressive treatment with darkness the cells were exposed to light which reactivated mitotic activity after 18-20 hours. Eight-celled antheridial filaments were observed. In the period preceding light-induced re-initiation of mitoses a gradual reconstruction of the number and size of nucleoli characteristic of control, as well as their total area per nucleus appeared. The obtained results indicate that one of the important conditions for a cell to be able to divide is accumulation of nucleolus components characteristic of a given developmental stage and this controls nucleologenesis of the subsequent cell cycle.

  2. Pancreatin-EDTA treatment affects buoyancy of cells in Cohn fraction V protein density gradients without residual effect on cell size.

    Science.gov (United States)

    Sheridan, J W; Simmons, R J

    1983-12-01

    The buoyancy of suspension-grown Mastocytoma P815 X-2 cells in albumin-rich Cohn fraction V protein (CFVP) density gradients was found to be affected by prior incubation of the cells in pancreatin-EDTA salt solution. Whereas in pH 5.2 CFVP, pancreatin-EDTA treated cells behaved as if of reduced density when compared with the control 'undigested' group, in pH 7.3 CFVP they behaved as if of increased density. By contrast, pancreatin-EDTA treatment had no effect on the buoyancy of mastocytoma cells in polyvinylpyrrolidone-coated colloidal silica (PVP-CS, Percoll T.M.) density gradients of either pH 5.2 or pH 7.3. As cell size determinations failed to reveal alterations in cell size either as a direct result of pancreatin-EDTA treatment or as a combined consequence of such treatment and exposure to CFVP either with or without centrifugation, a mechanism involving a change in cell density other than during the centrifugation process itself seems unlikely. Binding studies employing 125I-CFVP, although indicating that CFVP bound to cells at 4 degrees, failed to reveal a pancreatin-EDTA treatment-related difference in the avidity of this binding. Although the mechanism of the pancreatin-EDTA-induced buoyancy shift in CFVP remains obscure, the absence of such an effect in PVP-CS suggests that the latter cell separation solution may more accurately be used to determine cell density.

  3. Sizing for fuel cell/supercapacitor hybrid vehicles based on stochastic driving cycles

    International Nuclear Information System (INIS)

    Feroldi, Diego; Carignano, Mauro

    2016-01-01

    Highlights: • A sizing procedure based on the fulfilment of real driving conditions is proposed. • A methodology to generate long-term stochastic driving cycles is proposed. • A parametric optimization of the real-time EMS is conducted. • A trade-off design is adopted from a Pareto front. • A comparison with optimal consumption via Dynamic Programming is performed. - Abstract: In this article, a methodology for the sizing and analysis of fuel cell/supercapacitor hybrid vehicles is presented. The proposed sizing methodology is based on the fulfilment of power requirements, including sustained speed tests and stochastic driving cycles. The procedure to generate driving cycles is also presented in this paper. The sizing algorithm explicitly accounts for the Equivalent Consumption Minimization Strategy (ECMS). The performance is compared with optimal consumption, which is found using an off-line strategy via Dynamic Programming. The sizing methodology provides guidance for sizing the fuel cell and the supercapacitor number. The results also include analysis on oversizing the fuel cell and varying the parameters of the energy management strategy. The simulation results highlight the importance of integrating sizing and energy management into fuel cell hybrid vehicles.

  4. Use of surfactants to control island size and density

    Science.gov (United States)

    Merrell, Jason; Liu, Feng; Stringfellow, Gerald B.

    2017-08-15

    Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

  5. Role of proteins in controlling selenium nanoparticle size

    International Nuclear Information System (INIS)

    Dobias, J; Suvorova, E I; Bernier-Latmani, R

    2011-01-01

    This work investigates the potential for harnessing the association of bacterial proteins to biogenic selenium nanoparticles (SeNPs) to control the size distribution and the morphology of the resultant SeNPs. We conducted a proteomic study and compared proteins associated with biogenic SeNPs produced by E. coli to chemically synthesized SeNPs as well as magnetite nanoparticles. We identified four proteins (AdhP, Idh, OmpC, AceA) that bound specifically to SeNPs and observed a narrower size distribution as well as more spherical morphology when the particles were synthesized chemically in the presence of proteins. A more detailed study of AdhP (alcohol dehydrogenase propanol-preferring) confirmed the strong affinity of this protein for the SeNP surface and revealed that this protein controlled the size distribution of the SeNPs and yielded a narrow size distribution with a three-fold decrease in the median size. These results support the assertion that protein may become an important tool in the industrial-scale synthesis of SeNPs of uniform size and properties.

  6. Robust organelle size extractions from elastic scattering measurements of single cells (Conference Presentation)

    Science.gov (United States)

    Cannaday, Ashley E.; Draham, Robert; Berger, Andrew J.

    2016-04-01

    The goal of this project is to estimate non-nuclear organelle size distributions in single cells by measuring angular scattering patterns and fitting them with Mie theory. Simulations have indicated that the large relative size distribution of organelles (mean:width≈2) leads to unstable Mie fits unless scattering is collected at polar angles less than 20 degrees. Our optical system has therefore been modified to collect angles down to 10 degrees. Initial validations will be performed on polystyrene bead populations whose size distributions resemble those of cell organelles. Unlike with the narrow bead distributions that are often used for calibration, we expect to see an order-of-magnitude improvement in the stability of the size estimates as the minimum angle decreases from 20 to 10 degrees. Scattering patterns will then be acquired and analyzed from single cells (EMT6 mouse cancer cells), both fixed and live, at multiple time points. Fixed cells, with no changes in organelle sizes over time, will be measured to determine the fluctuation level in estimated size distribution due to measurement imperfections alone. Subsequent measurements on live cells will determine whether there is a higher level of fluctuation that could be attributed to dynamic changes in organelle size. Studies on unperturbed cells are precursors to ones in which the effects of exogenous agents are monitored over time.

  7. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias C.; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

    2009-01-01

    Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

  8. Solid oxide fuel cell cathode infiltrate particle size control and oxygen surface exchange resistance determination

    Science.gov (United States)

    Burye, Theodore E.

    Over the past decade, nano-sized Mixed Ionic Electronic Conducting (MIEC) -- micro-sized Ionic Conducting (IC) composite cathodes produced by the infiltration method have received much attention in the literature due to their low polarization resistance (RP) at intermediate (500-700°C) operating temperatures. Small infiltrated MIEC oxide nano-particle size and low intrinsic MIEC oxygen surface exchange resistance (Rs) have been two critical factors allowing these Nano-Micro-Composite Cathodes (NMCCs) to achieve high performance and/or low temperature operation. Unfortunately, previous studies have not found a reliable method to control or reduce infiltrated nano-particle size. In addition, controversy exists on the best MIEC infiltrate composition because: 1) Rs measurements on infiltrated MIEC particles are presently unavailable in the literature, and 2) bulk and thin film Rs measurements on nominally identical MIEC compositions often vary by up to 3 orders of magnitude. Here, two processing techniques, precursor nitrate solution desiccation and ceria oxide pre-infiltration, were developed to systematically produce a reduction in the average La0.6Sr0.4Co0.8Fe 0.2O3-delta (LSCF) infiltrated nano-particle size from 50 nm to 22 nm. This particle size reduction reduced the SOFC operating temperature, (defined as the temperature where RP=0.1 Ocm 2) from 650°C to 540°C. In addition, Rs values for infiltrated MIEC particles were determined for the first time through finite element modeling calculations on 3D Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) reconstructions of electrochemically characterized infiltrated electrodes.

  9. A Study on Cell Size of Irradiated Spacer Grid for PWR Fuel

    International Nuclear Information System (INIS)

    Jin, Y. G.; Kim, G. S.; Ryu, W. S. and others

    2014-01-01

    The spacer grids supporting the fuel rods absorb vibration impacts due to the reactor coolant flow, and grid spring force decreases under irradiation. This reduction of contact force might cause grid-to-rod fretting wear. The fretting failure of the fuel rod is one of the recent significant issues in the nuclear industry from an economical as well as a safety concern. Thus, it is important to understand the characteristics of cell spring behavior and the change in size of grid cells for an irradiated spacer grid. In the present study, the dimensional measurement of a spacer grid was conducted to investigate the cell size of an irradiated spacer grid in a hot cell at IMEF (Irradiated Materials Examination Facility) of KAERI. To evaluate the fretting wear performance of an irradiated spacer grid, hot cell tests were carried out at IMEF of KAERI. Hot cell examinations include dimensional measurements for the irradiated spacer grid. The change of cell sizes was dependent on the direction of the spacer grids, leading to significant gap variations. It was found that the change in size of the cell springs due to irradiation-induced stress relaxation and creep during the fuel residency in the reactor core affect the contact behavior between the fuel rod and the cell spring

  10. The BAR Domain Protein PICK1 Controls Vesicle Number and Size in Adrenal Chromaffin Cells

    DEFF Research Database (Denmark)

    da Silva Pinheiro, Paulo César; Jansen, Anna M; de Wit, Heidi

    2014-01-01

    , a marker for immature granules. In chromaffin cells isolated from a PICK1 knockout (KO) mouse the amount of exocytosis was reduced, while release kinetics and Ca(2+) sensitivity were unaffected. Vesicle-fusion events had a reduced frequency and released lower amounts of transmitter per vesicle (i...... in vesicle number and size, whereas the fusion competence of generated vesicles was unaffected by the absence of PICK1. Viral rescue experiments demonstrated that long-term re-expression of PICK1 is necessary to restore normal vesicular content and secretion, while short-term overexpression is ineffective...

  11. Impact of radiation therapy fraction size on local control of early glottic carcinoma

    International Nuclear Information System (INIS)

    Yu, Edward; Shenouda, George; Beaudet, Marie P.; Black, Martin J.

    1997-01-01

    Purpose: Different radiotherapy fractionation schedules were used over a 10-year period to treat patients with early squamous cell carcinoma of the vocal cords at McGill University. A retrospective analysis was performed to study the effect of fraction size on local control in this group of patients. Methods and Materials: A total of 126 previously untreated patients with T1 invasive squamous cell carcinoma of the true vocal cords were irradiated between January 1978 and December 1988 in the Department of Radiation Oncology at McGill University. All patients received megavoltage irradiation, 94 patients received daily fractions > 2 Gy (64 patients received 50 Gy with once-daily 2.5-Gy fractions, and 30 received 65.25 Gy in 29 fractions of 2.25 Gy each), and 32 patients were treated to a dose of 66 Gy in 33 fractions with 2 Gy/fraction. Patients' characteristics of prognostic importance were equally distributed between the two fractionation groups. Results: At a median follow-up of 84 months, the 10-year disease-free survival and overall survival were 76% and 93%, respectively. Local control for patients treated with > 2 Gy fraction was 84%, compared to 65.6% for those treated with 2-Gy fractions (p = 0.026). Among the prognostic factors tested, such as gender, age, stage, anterior and posterior commissure involvement, smoking history, and fraction size, the latter was the only significant predictor of local control for the whole group of patients in univariate (p = 0.041) and multivariate (p = 0.023) analysis. There was no observed difference in the incidence of complications between the two fraction groups. Conclusions: From the results of this retrospective review of patients treated with radiotherapy for T1 true vocal cord cancer, and within the range of total doses and overall treatment times used in our patients, it was found that fractionation schedules using daily fraction size > 2 Gy are associated with a better local control than schedules delivering 2 Gy

  12. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    Science.gov (United States)

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  13. Optimal Sizing and Control Strategy Design for Heavy Hybrid Electric Truck

    Directory of Open Access Journals (Sweden)

    Yuan Zou

    2012-01-01

    Full Text Available Due to the complexity of the hybrid powertrain, the control is highly involved to improve the collaborations of the different components. For the specific powertrain, the components' sizing just gives the possibility to propel the vehicle and the control will realize the function of the propulsion. Definitely the components' sizing also gives the constraints to the control design, which cause a close coupling between the sizing and control strategy design. This paper presents a parametric study focused on sizing of the powertrain components and optimization of the power split between the engine and electric motor for minimizing the fuel consumption. A framework is put forward to accomplish the optimal sizing and control design for a heavy parallel pre-AMT hybrid truck under the natural driving schedule. The iterative plant-controller combined optimization methodology is adopted to optimize the key parameters of the plant and control strategy simultaneously. A scalable powertrain model based on a bilevel optimization framework is built. Dynamic programming is applied to find the optimal control in the inner loop with a prescribed cycle. The parameters are optimized in the outer loop. The results are analysed and the optimal sizing and control strategy are achieved simultaneously.

  14. Not all cells are equal: effects of temperature and sex on the size of different cell types in the Madagascar ground gecko Paroedura picta

    Directory of Open Access Journals (Sweden)

    Marcin Czarnoleski

    2017-08-01

    Full Text Available Cell size plays a role in evolutionary and phenotypically plastic changes in body size. To examine this role, we measured the sizes of seven cell types of geckos (Paroedura picta reared at three constant temperatures (24, 27, and 30°C. Our results show that the cell size varies according to the body size, sex and developmental temperature, but the pattern of this variance depends on the cell type. We identified three groups of cell types, and the cell sizes changed in a coordinated manner within each group. Larger geckos had larger erythrocytes, striated muscle cells and hepatocytes (our first cell group, but their renal proximal tubule cells and duodenal enterocytes (our second cell group, as well as tracheal chondrocytes and epithelial skin cells (our third cell group, were largely unrelated to the body size. For six cell types, we also measured the nuclei and found that larger cells had larger nuclei. The relative sizes of the nuclei were not invariant but varied in a complex manner with temperature and sex. In conclusion, we provide evidence suggesting that changes in cell size might be commonly involved in the origin of thermal and sexual differences in adult size. A recent theory predicts that smaller cells speed up metabolism but demand more energy for their maintenance; consequently, the cell size matches the metabolic demand and supply, which in ectotherms, largely depends on the thermal conditions. The complex thermal dependency of cell size in geckos suggests that further advancements in understanding the adaptive value of cell size requires the consideration of tissue-specific demand/supply conditions.

  15. Cell Control Engineering

    DEFF Research Database (Denmark)

    Lynggaard, Hans Jørgen Birk; Alting, Leo

    1996-01-01

    The engineering process of creating cell control systems is described, and a Cell Control Engineering (CCE) concept is defined. The purpose is to assist people, representing different disciplines in the organisation, to implement cell controllers by addressing the complexity of having many systems...... in physically and logically different and changing manufacturing environments. The defined CCE concept combines state-of-the-art of commercially available enabling technologies for automation system software development, generic cell control models and guidelines for the complete engineering process...

  16. Revisionist integral deferred correction with adaptive step-size control

    KAUST Repository

    Christlieb, Andrew

    2015-03-27

    © 2015 Mathematical Sciences Publishers. Adaptive step-size control is a critical feature for the robust and efficient numerical solution of initial-value problems in ordinary differential equations. In this paper, we show that adaptive step-size control can be incorporated within a family of parallel time integrators known as revisionist integral deferred correction (RIDC) methods. The RIDC framework allows for various strategies to implement stepsize control, and we report results from exploring a few of them.

  17. Controlled size and one-dimensional growth

    Indian Academy of Sciences (India)

    875–881. c Indian Academy of Sciences. Synthesis of azamacrocycle stabilized palladium nanoparticles: Controlled size and one-dimensional growth. JEYARAMAN ATHILAKSHMI and DILLIP KUMAR CHAND. ∗. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India e-mail: dillip@iitm.ac.

  18. Cell cycle control by components of cell anchorage

    OpenAIRE

    Gad, Annica

    2005-01-01

    Extracellular factors, such as growth factors and cell anchorage to the extracellular matrix, control when and where cells may proliferate. This control is abolished when a normal cell transforms into a tumour cell. The control of cell proliferation by cell anchorage was elusive and less well studied than the control by growth factors. Therefore, we aimed to clarify at what points in the cell cycle and through which molecular mechanisms cell anchorage controls cell cycle pro...

  19. Three-Dimensional Spatiotemporal Modeling of Colon Cancer Organoids Reveals that Multimodal Control of Stem Cell Self-Renewal is a Critical Determinant of Size and Shape in Early Stages of Tumor Growth.

    Science.gov (United States)

    Yan, Huaming; Konstorum, Anna; Lowengrub, John S

    2018-05-01

    We develop a three-dimensional multispecies mathematical model to simulate the growth of colon cancer organoids containing stem, progenitor and terminally differentiated cells, as a model of early (prevascular) tumor growth. Stem cells (SCs) secrete short-range self-renewal promoters (e.g., Wnt) and their long-range inhibitors (e.g., Dkk) and proliferate slowly. Committed progenitor (CP) cells proliferate more rapidly and differentiate to produce post-mitotic terminally differentiated cells that release differentiation promoters, forming negative feedback loops on SC and CP self-renewal. We demonstrate that SCs play a central role in normal and cancer colon organoids. Spatial patterning of the SC self-renewal promoter gives rise to SC clusters, which mimic stem cell niches, around the organoid surface, and drive the development of invasive fingers. We also study the effects of externally applied signaling factors. Applying bone morphogenic proteins, which inhibit SC and CP self-renewal, reduces invasiveness and organoid size. Applying hepatocyte growth factor, which enhances SC self-renewal, produces larger sizes and enhances finger development at low concentrations but suppresses fingers at high concentrations. These results are consistent with recent experiments on colon organoids. Because many cancers are hierarchically organized and are subject to feedback regulation similar to that in normal tissues, our results suggest that in cancer, control of cancer stem cell self-renewal should influence the size and shape in similar ways, thereby opening the door to novel therapies.

  20. Cell control report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This extensive report provides an essential overview of cells and their use as factory automation building blocks. The following issues are discussed in depth: Cell integration Cell software and standards Future technologies applied to cells Plus Cell control applications including: - rotary parts manufacturing - diesel engine component development - general cell control development at the General Electric Corporation - a vendor list.

  1. Birth order, sibship size, and risk for germ-cell testicular cancer.

    Science.gov (United States)

    Richiardi, Lorenzo; Akre, Olof; Lambe, Mats; Granath, Fredrik; Montgomery, Scott M; Ekbom, Anders

    2004-05-01

    Several studies have reported an inverse association between birth order and testicular cancer risk, but estimates vary greatly and the biologic mechanism underlying the association is not established. We have evaluated the effect of birth order, sibship size, and the combined effect of these 2 variables in relation to risk for testicular cancer in a large, nested case-control study. Specifically, we compared 3051 patients with germ-cell testicular cancer (diagnosed between 1958 and 1998 and identified through the Swedish Cancer Registry) with 9007 population control subjects. Using record linkage with the Multi-Generation Register and the Census, we obtained information on number, order, and sex of the subjects' siblings, parental age, and paternal socioeconomic status. Both birth order and sibship size had an inverse and monotonically decreasing association with testicular cancer risk after adjusting for parental age, paternal socioeconomic status, and twin status. The associations were modified by subjects' cohort of birth and were not present among those born after 1959. The odds ratio for having at least 3 siblings, compared with none, was 0.63 (95% confidence interval = 0.53-0.75) among subjects born before 1960. Stratified analyses showed that birth order and number of younger siblings had a similar inverse association with the risk for testicular cancer. Sibship size, and not only birth order, is associated with testicular cancer risk. This suggests a higher prevalence of parental subfertility among patients with testicular cancer.

  2. Sonochemical synthesis of silica particles and their size control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

    2016-09-01

    Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

  3. Energetic tradeoffs control the size distribution of aquatic mammals

    Science.gov (United States)

    Gearty, William; McClain, Craig R.; Payne, Jonathan L.

    2018-04-01

    Four extant lineages of mammals have invaded and diversified in the water: Sirenia, Cetacea, Pinnipedia, and Lutrinae. Most of these aquatic clades are larger bodied, on average, than their closest land-dwelling relatives, but the extent to which potential ecological, biomechanical, and physiological controls contributed to this pattern remains untested quantitatively. Here, we use previously published data on the body masses of 3,859 living and 2,999 fossil mammal species to examine the evolutionary trajectories of body size in aquatic mammals through both comparative phylogenetic analysis and examination of the fossil record. Both methods indicate that the evolution of an aquatic lifestyle is driving three of the four extant aquatic mammal clades toward a size attractor at ˜500 kg. The existence of this body size attractor and the relatively rapid selection toward, and limited deviation from, this attractor rule out most hypothesized drivers of size increase. These three independent body size increases and a shared aquatic optimum size are consistent with control by differences in the scaling of energetic intake and cost functions with body size between the terrestrial and aquatic realms. Under this energetic model, thermoregulatory costs constrain minimum size, whereas limitations on feeding efficiency constrain maximum size. The optimum size occurs at an intermediate value where thermoregulatory costs are low but feeding efficiency remains high. Rather than being released from size pressures, water-dwelling mammals are driven and confined to larger body sizes by the strict energetic demands of the aquatic medium.

  4. Lipoplex size determines lipofection efficiency with or without serum.

    Science.gov (United States)

    Almofti, Mohamad Radwan; Harashima, Hideyoshi; Shinohara, Yasuo; Almofti, Ammar; Li, Wenhao; Kiwada, Hiroshi

    2003-01-01

    In order to identify factors affecting cationic liposome-mediated gene transfer, the relationships were examined among cationic liposome/DNA complex (lipoplex)-cell interactions, lipoplex size and lipoplex-mediated transfection (lipofection) efficiency. It was found that lipofection efficiency was determined mainly by lipoplex size, but not by the extent of lipoplex-cell interactions including binding, uptake or fusion. In addition, it was found that serum affected mainly lipoplex size, but not lipoplex-cell interactions, which effect was the major reason behind the inhibitory effect of serum on lipofection efficiency. It was concluded that, in the presence or absence of serum, lipoplex size is a major factor determining lipofection efficiency. Moreover, in the presence or absence of serum, lipoplex size was found to affect lipofection efficiency by controlling the size of the intracellular vesicles containing lipoplexes after internalization, but not by affecting lipoplex-cell interactions. In addition, large lipoplex particles showed, in general, higher lipofection efficiency than small particles. These results imply that, by controlling lipoplex size, an efficient lipid delivery system may be achieved for in vitro and in vivo gene therapy.

  5. Controlling semiconductor nanoparticle size distributions with tailored ultrashort pulses

    International Nuclear Information System (INIS)

    Hergenroeder, R; Miclea, M; Hommes, V

    2006-01-01

    The laser generation of size-controlled semiconductor nanoparticle formation under gas phase conditions is investigated. It is shown that the size distribution can be changed if picosecond pulse sequences of tailored ultra short laser pulses (<200 fs) are employed. By delivering the laser energy in small packages, a temporal energy flux control at the target surface is achieved, which results in the control of the thermodynamic pathway the material takes. The concept is tested with silicon and germanium, both materials with a predictable response to double pulse sequences, which allows deduction of the materials' response to complicated pulse sequences. An automatic, adaptive learning algorithm was employed to demonstrate a future strategy that enables the definition of more complex optimization targets such as particle size on materials less predictable than semiconductors

  6. Cell lineage branching as a strategy for proliferative control.

    Science.gov (United States)

    Buzi, Gentian; Lander, Arthur D; Khammash, Mustafa

    2015-02-19

    How tissue and organ sizes are specified is one of the great unsolved mysteries in biology. Experiments and mathematical modeling implicate feedback control of cell lineage progression, but a broad understanding of what lineage feedback accomplishes is lacking. By exploring the possible effects of various biologically relevant disturbances on the dynamic and steady state behaviors of stem cell lineages, we find that the simplest and most frequently studied form of lineage feedback - which we term renewal control - suffers from several serious drawbacks. These reflect fundamental performance limits dictated by universal conservation-type laws, and are independent of parameter choice. Here we show that introducing lineage branches can circumvent all such limitations, permitting effective attenuation of a wide range of perturbations. The type of feedback that achieves such performance - which we term fate control - involves promotion of lineage branching at the expense of both renewal and (primary) differentiation. We discuss the evidence that feedback of just this type occurs in vivo, and plays a role in tissue growth control. Regulated lineage branching is an effective strategy for dealing with disturbances in stem cell systems. The existence of this strategy provides a dynamics-based justification for feedback control of cell fate in vivo.

  7. Economic Effects of Increased Control Zone Sizes in Conflict Resolution

    Science.gov (United States)

    Datta, Koushik

    1998-01-01

    A methodology for estimating the economic effects of different control zone sizes used in conflict resolutions between aircraft is presented in this paper. The methodology is based on estimating the difference in flight times of aircraft with and without the control zone, and converting the difference into a direct operating cost. Using this methodology the effects of increased lateral and vertical control zone sizes are evaluated.

  8. On the size distribution of one-, two- and three-dimensional Voronoi cells

    International Nuclear Information System (INIS)

    Marthinsen, K.

    1994-03-01

    The present report gives a presentation of the different cell size distribution obtained by computer simulations of random Voronoi cell structures in one-, two- and three-dimensional space. The random Voronoi cells are constructed from cell centroids randomly distributed along a string, in the plane and in three-dimensional space, respectively. The size distributions are based on 2-3 · 10 4 cells. For the spacial polyhedra both the distribution of volumes, areas and radii are presented, and the two latter quantities are compared to the distributions of areas and radii from a planar section through the three-dimensional structure as well as to the corresponding distributions obtained from a pure two-dimensional cell structure. 11 refs., 11 figs

  9. Cellular size as a means of tracking mTOR activity and cell fate of CD4+ T cells upon antigen recognition.

    Directory of Open Access Journals (Sweden)

    Kristen N Pollizzi

    Full Text Available mTOR is a central integrator of metabolic and immunological stimuli, dictating immune cell activation, proliferation and differentiation. In this study, we demonstrate that within a clonal population of activated T cells, there exist both mTORhi and mTORlo cells exhibiting highly divergent metabolic and immunologic functions. By taking advantage of the role of mTOR activation in controlling cellular size, we demonstrate that upon antigen recognition, mTORhi CD4+ T cells are destined to become highly glycolytic effector cells. Conversely, mTORlo T cells preferentially develop into long-lived cells that express high levels of Bcl-2, CD25, and CD62L. Furthermore, mTORlo T cells have a greater propensity to differentiate into suppressive Foxp3+ T regulatory cells, and this paradigm was also observed in human CD4+ T cells. Overall, these studies provide the opportunity to track the development of effector and memory T cells from naïve precursors, as well as facilitate the interrogation of immunologic and metabolic programs that inform these fates.

  10. Response of MG63 osteoblast-like cells onto polycarbonate membrane surfaces with different micropore sizes.

    Science.gov (United States)

    Lee, Sang Jin; Choi, Jin San; Park, Ki Suk; Khang, Gilson; Lee, Young Moo; Lee, Hai Bang

    2004-08-01

    Response of different types of cells on materials is important for the applications of tissue engineering and regenerative medicine. It is recognized that the behavior of the cell adhesion, proliferation, and differentiation on materials depends largely on surface characteristics such as wettability, chemistry, charge, rigidity, and roughness. In this study, we examined the behavior of MG63 osteoblast-like cells cultured on a polycarbonate (PC) membrane surfaces with different micropore sizes (0.2-8.0 microm in diameter). Cell adhesion and proliferation to the PC membrane surfaces were determined by cell counting and MTT assay. The effect of surface micropore on the MG63 cells was evaluated by cell morphology, protein content, and alkaline phosphatase (ALP) specific activity. It seems that the cell adhesion and proliferation were progressively inhibited as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. Increasing micropore size of the PC membrane results in improved protein synthesis and ALP specific activity in isolated cells. There was a statistically significant difference (Pmicropore sizes. The MG63 cells also maintained their phenotype under conditions that support a round cell shape. RT-PCR analysis further confirmed the osteogenic phenotype of the MG63 cells onto the PC membranes with different micropore sizes. In results, as micropore size is getting larger, cell number is reduced and cell differentiation and matrix production is increased. This study demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells.

  11. Small-size biofuel cell on paper.

    Science.gov (United States)

    Zhang, Lingling; Zhou, Ming; Wen, Dan; Bai, Lu; Lou, Baohua; Dong, Shaojun

    2012-05-15

    In this work, we demonstrated a novel paper-based mediator-less and compartment-less biofuel cell (BFC) with small size (1.5 cm × 1.5 cm). Ionic liquid functionalized carbon nanotubes (CNTs-IL) nanocomposite was used as support for both stably confining the anodic biocatalyst (i.e., NAD(+)-dependent glucose dehydrogenase, GDH) for glucose electrooxidation and for facilitating direct electrochemistry of the cathodic biocatalyst (i.e., bilirubin oxidase, BOD) for O(2) electroreduction. Such BFC provided a simple approach to fabricate low-cost and portable power devices on small-size paper, which can harvest energy from a wide range of commercial beverages containing glucose (e.g., Nescafe instant coffee, Maidong vitamin water, Watermelon fresh juice, and Minute Maid grape juice). These made the low-cost paper-based biodevice potential for broad energy applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Size Matters, if you Control Your Junk

    DEFF Research Database (Denmark)

    Asness, Cliff; Frazzini, Andrea; Israel, Ronen

    The size premium has been challenged along many fronts: it has a weak historical record, varies significantly over time, in particular weakening after its discovery, is concentrated among microcap stocks, resides predominantly in January, is not present for non-price based measures of size, is weak...... emerges, which is: stable through time, robust to specification, more consistent across seasons and markets, not concentrated in microcaps, robust to non-price based measures of size, and not captured by an illiquidity premium. These results are replicated in 30 different industries and in 24 different...... internationally, and is argued to be subsumed by proxies for illiquidity. We find, however, that these challenges are systematically dismantled when controlling for the quality, or its inverse “junk”, of a firm. Across a wide variety of quality measures proposed in the literature a significant size premium...

  13. Cell cycle control by a minimal Cdk network.

    Directory of Open Access Journals (Sweden)

    Claude Gérard

    2015-02-01

    Full Text Available In present-day eukaryotes, the cell division cycle is controlled by a complex network of interacting proteins, including members of the cyclin and cyclin-dependent protein kinase (Cdk families, and the Anaphase Promoting Complex (APC. Successful progression through the cell cycle depends on precise, temporally ordered regulation of the functions of these proteins. In light of this complexity, it is surprising that in fission yeast, a minimal Cdk network consisting of a single cyclin-Cdk fusion protein can control DNA synthesis and mitosis in a manner that is indistinguishable from wild type. To improve our understanding of the cell cycle regulatory network, we built and analysed a mathematical model of the molecular interactions controlling the G1/S and G2/M transitions in these minimal cells. The model accounts for all observed properties of yeast strains operating with the fusion protein. Importantly, coupling the model's predictions with experimental analysis of alternative minimal cells, we uncover an explanation for the unexpected fact that elimination of inhibitory phosphorylation of Cdk is benign in these strains while it strongly affects normal cells. Furthermore, in the strain without inhibitory phosphorylation of the fusion protein, the distribution of cell size at division is unusually broad, an observation that is accounted for by stochastic simulations of the model. Our approach provides novel insights into the organization and quantitative regulation of wild type cell cycle progression. In particular, it leads us to propose a new mechanistic model for the phenomenon of mitotic catastrophe, relying on a combination of unregulated, multi-cyclin-dependent Cdk activities.

  14. Concerted evolution of body mass and cell size: similar patterns among species of birds (Galliformes) and mammals (Rodentia)

    Science.gov (United States)

    Dragosz-Kluska, Dominika; Pis, Tomasz; Pawlik, Katarzyna; Kapustka, Filip; Kilarski, Wincenty M.; Kozłowski, Jan

    2018-01-01

    ABSTRACT Cell size plays a role in body size evolution and environmental adaptations. Addressing these roles, we studied body mass and cell size in Galliformes birds and Rodentia mammals, and collected published data on their genome sizes. In birds, we measured erythrocyte nuclei and basal metabolic rates (BMRs). In birds and mammals, larger species consistently evolved larger cells for five cell types (erythrocytes, enterocytes, chondrocytes, skin epithelial cells, and kidney proximal tubule cells) and evolved smaller hepatocytes. We found no evidence that cell size differences originated through genome size changes. We conclude that the organism-wide coordination of cell size changes might be an evolutionarily conservative characteristic, and the convergent evolutionary body size and cell size changes in Galliformes and Rodentia suggest the adaptive significance of cell size. Recent theory predicts that species evolving larger cells waste less energy on tissue maintenance but have reduced capacities to deliver oxygen to mitochondria and metabolize resources. Indeed, birds with larger size of the abovementioned cell types and smaller hepatocytes have evolved lower mass-specific BMRs. We propose that the inconsistent pattern in hepatocytes derives from the efficient delivery system to hepatocytes, combined with their intense involvement in supracellular function and anabolic activity. PMID:29540429

  15. Concerted evolution of body mass and cell size: similar patterns among species of birds (Galliformes and mammals (Rodentia

    Directory of Open Access Journals (Sweden)

    Marcin Czarnoleski

    2018-04-01

    Full Text Available Cell size plays a role in body size evolution and environmental adaptations. Addressing these roles, we studied body mass and cell size in Galliformes birds and Rodentia mammals, and collected published data on their genome sizes. In birds, we measured erythrocyte nuclei and basal metabolic rates (BMRs. In birds and mammals, larger species consistently evolved larger cells for five cell types (erythrocytes, enterocytes, chondrocytes, skin epithelial cells, and kidney proximal tubule cells and evolved smaller hepatocytes. We found no evidence that cell size differences originated through genome size changes. We conclude that the organism-wide coordination of cell size changes might be an evolutionarily conservative characteristic, and the convergent evolutionary body size and cell size changes in Galliformes and Rodentia suggest the adaptive significance of cell size. Recent theory predicts that species evolving larger cells waste less energy on tissue maintenance but have reduced capacities to deliver oxygen to mitochondria and metabolize resources. Indeed, birds with larger size of the abovementioned cell types and smaller hepatocytes have evolved lower mass-specific BMRs. We propose that the inconsistent pattern in hepatocytes derives from the efficient delivery system to hepatocytes, combined with their intense involvement in supracellular function and anabolic activity.

  16. Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

    Science.gov (United States)

    Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

    2011-08-01

    • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  17. Introducing micrometer-sized artificial objects into live cells: a method for cell-giant unilamellar vesicle electrofusion.

    Directory of Open Access Journals (Sweden)

    Akira C Saito

    Full Text Available Here, we report a method for introducing large objects of up to a micrometer in diameter into cultured mammalian cells by electrofusion of giant unilamellar vesicles. We prepared GUVs containing various artificial objects using a water-in-oil (w/o emulsion centrifugation method. GUVs and dispersed HeLa cells were exposed to an alternating current (AC field to induce a linear cell-GUV alignment, and then a direct current (DC pulse was applied to facilitate transient electrofusion. With uniformly sized fluorescent beads as size indexes, we successfully and efficiently introduced beads of 1 µm in diameter into living cells along with a plasmid mammalian expression vector. Our electrofusion did not affect cell viability. After the electrofusion, cells proliferated normally until confluence was reached, and the introduced fluorescent beads were inherited during cell division. Analysis by both confocal microscopy and flow cytometry supported these findings. As an alternative approach, we also introduced a designed nanostructure (DNA origami into live cells. The results we report here represent a milestone for designing artificial symbiosis of functionally active objects (such as micro-machines in living cells. Moreover, our technique can be used for drug delivery, tissue engineering, and cell manipulation.

  18. In vitro toxicity of different-sized ZnO nanoparticles in Caco-2 cells

    Science.gov (United States)

    Kang, Tianshu; Guan, Rongfa; Chen, Xiaoqiang; Song, Yijuan; Jiang, Han; Zhao, Jin

    2013-11-01

    There has been rapid growth in nanotechnology in both the public and private sectors worldwide, but concern about nanosafety exists. To assess size-dependent cytotoxicity on human cancer cells, we studied the cytotoxic effect of three kinds of zinc oxide nanoparticles (ZnO NPs) on human epithelial colorectal adenocarcinoma (Caco-2) cells. Nanoparticles were first characterized by size, distribution, and intensity. Multiple assays have been adopted to measure the cell activity and oxidative stress. The cytotoxicity of ZnO NPs was time dependent and dose dependent. The 24-h exposure was chosen to confirm the viability and accessibility of the cells and taken as the appropriate time for the following test system. The IC50 value was found at a low concentration. The oxidative stress elicited a significant reduction in glutathione with increase in reactive oxygen species and lactate dehydrogenase. The toxicity resulted in a deletion of cells in the G1 phase and an accumulation of cells in the S and G2/M phases. One type of metallic oxide (ZnO) exerted different cytotoxic effects according to different particle sizes. Data from the previous experiments showed that 26-nm ZnO NPs appeared to have the highest toxicity to Caco-2 cells. The study demonstrated the toxicity of ZnO NPs to Caco-2 cells and the impact of particle size, which could be useful in the medical applications.

  19. β-Glucan Size Controls Dectin-1-Mediated Immune Responses in Human Dendritic Cells by Regulating IL-1β Production

    Directory of Open Access Journals (Sweden)

    Matthew J. Elder

    2017-07-01

    Full Text Available Dectin-1/CLEC7A is a pattern recognition receptor that recognizes β-1,3 glucans, and its stimulation initiates signaling events characterized by the production of inflammatory cytokines from human dendritic cells (DCs required for antifungal immunity. β-glucans differ greatly in size, structure, and ability to activate effector immune responses from DC; as such, small particulate β-glucans are thought to be poor activators of innate immunity. We show that β-glucan particle size is a critical factor contributing to the secretion of cytokines from human DC; large β-glucan-stimulated DC generate significantly more IL-1β, IL-6, and IL-23 compared to those stimulated with the smaller β-glucans. In marked contrast, the secretion of TSLP and CCL22 were found to be insensitive to β-glucan particle size. Furthermore, we show that the capacity to induce phagocytosis, and the relative IL-1β production determined by β-glucan size, regulates the composition of the cytokine milieu generated from DC. This suggests that β-glucan particle size is critically important in orchestrating the nature of the immune response to fungi.

  20. Optochemical Control of Protein Localization and Activity within Cell-like Compartments.

    Science.gov (United States)

    Caldwell, Reese M; Bermudez, Jessica G; Thai, David; Aonbangkhen, Chanat; Schuster, Benjamin S; Courtney, Taylor; Deiters, Alexander; Hammer, Daniel A; Chenoweth, David M; Good, Matthew C

    2018-05-08

    We report inducible dimerization strategies for controlling protein positioning, enzymatic activity, and organelle assembly inside synthetic cell-like compartments upon photostimulation. Using a photocaged TMP-Haloligand compound, we demonstrate small molecule and light-induced dimerization of DHFR and Haloenzyme to localize proteins to a compartment boundary and reconstitute tripartite sfGFP assembly. Using photocaged rapamycin and fragments of split TEV protease fused to FRB and FKBP, we establish optical triggering of protease activity inside cell-size compartments. We apply light-inducible protease activation to initiate assembly of membraneless organelles, demonstrating the applicability of these tools for characterizing cell biological processes in vitro. This modular toolkit, which affords spatial and temporal control of protein function in a minimal cell-like system, represents a critical step toward the reconstitution of a tunable synthetic cell, built from the bottom up.

  1. A comparative study of U937 cell size changes during apoptosis initiation by flow cytometry, light scattering, water assay and electronic sizing.

    Science.gov (United States)

    Yurinskaya, Valentina; Aksenov, Nikolay; Moshkov, Alexey; Model, Michael; Goryachaya, Tatyana; Vereninov, Alexey

    2017-10-01

    A decrease in flow cytometric forward light scatter (FSC) is commonly interpreted as a sign of apoptotic cell volume decrease (AVD). However, the intensity of light scattering depends not only on the cell size but also on its other characteristics, such as hydration, which may affect the scattering in the opposite way. That makes estimation of AVD by FSC problematic. Here, we aimed to clarify the relationship between light scattering, cell hydration (assayed by buoyant density) and cell size by the Coulter technique. We used human lymphoid cells U937 exposed to staurosporine, etoposide or hypertonic stress as an apoptotic model. An initial increase in FSC was found to occur in apoptotic cells treated with staurosporine and hypertonic solutions; it is accompanied by cell dehydration and is absent in apoptosis caused by etoposide that is consistent with the lack of dehydration in this case. Thus, the effect of dehydration on the scattering signal outweighs the effect of reduction in cell size. The subsequent FSC decrease, which occurred in parallel to accumulation of annexin-positive cells, was similar in apoptosis caused by all three types of inducers. We conclude that an increase, but not a decrease in light scattering, indicates the initial cell volume decrease associated with apoptotic cell dehydration.

  2. Control of cell proliferation by a porous chitosan scaffold with multiple releasing capabilities

    Science.gov (United States)

    Cai, Shu-Jyun; Li, Ching-Wen; Weihs, Daphne; Wang, Gou-Jen

    2017-01-01

    Abstract The aim of this study was to develop a porous chitosan scaffold with long-acting drug release as an artificial dressing to promote skin wound healing. The dressing was fabricated by pre-freezing at different temperatures (−20 and −80 °C) for different periods of time, followed by freeze-drying to form porous chitosan scaffolds with different pore sizes. The chitosan scaffolds were then used to investigate the effect of the controlled release of fibroblast growth factor-basic (bFGF) and transforming growth factor-β1 (TGFβ1) on mouse fibroblast cells (L929) and bovine carotid endothelial cells (BEC). The biocompatibility of the prepared chitosan scaffold was confirmed with WST-1 proliferation and viability assay, which demonstrated that the material is suitable for cell growth. The results of this study show that the pore sizes of the porous scaffolds prepared by freeze-drying can change depending on the pre-freezing temperature and time via the formation of ice crystals. In this study, the scaffolds with the largest pore size were found to be 153 ± 32 μm and scaffolds with the smallest pores to be 34 ± 9 μm. Through cell culture analysis, it was found that the concentration that increased proliferation of L929 cells for bFGF was 0.005 to 0.1 ng/mL, and the concentration for TGFβ1 was 0.005 to 1 ng/mL. The cell culture of the chitosan scaffold and growth factors shows that 3.75 ng of bFGF in scaffolds with pore sizes of 153 ± 32 μm can promote L929 cell proliferation, while 400 pg of TGFβ1 in scaffolds with pore size of 34 ± 9 μm can enhance the proliferation of L929 cells, but also inhibit BEC proliferation. It is proposed that the prepared chitosan scaffolds can form a multi-drug (bFGF and TGFβ1) release dressing that has the ability to control wound healing via regulating the proliferation of different cell types. PMID:29230255

  3. Size and targeting to PECAM vs ICAM control endothelial delivery, internalization and protective effect of multimolecular SOD conjugates.

    Science.gov (United States)

    Shuvaev, Vladimir V; Muro, Silvia; Arguiri, Evguenia; Khoshnejad, Makan; Tliba, Samira; Christofidou-Solomidou, Melpo; Muzykantov, Vladimir R

    2016-07-28

    Controlled endothelial delivery of SOD may alleviate abnormal local surplus of superoxide involved in ischemia-reperfusion, inflammation and other disease conditions. Targeting SOD to endothelial surface vs. intracellular compartments is desirable to prevent pathological effects of external vs. endogenous superoxide, respectively. Thus, SOD conjugated with antibodies to cell adhesion molecule PECAM (Ab/SOD) inhibits pro-inflammatory signaling mediated by endogenous superoxide produced in the endothelial endosomes in response to cytokines. Here we defined control of surface vs. endosomal delivery and effect of Ab/SOD, focusing on conjugate size and targeting to PECAM vs. ICAM. Ab/SOD enlargement from about 100 to 300nm enhanced amount of cell-bound SOD and protection against extracellular superoxide. In contrast, enlargement inhibited endocytosis of Ab/SOD and diminished mitigation of inflammatory signaling of endothelial superoxide. In addition to size, shape is important: endocytosis of antibody-coated spheres was more effective than that of polymorphous antibody conjugates. Further, targeting to ICAM provides higher endocytic efficacy than targeting to PECAM. ICAM-targeted Ab/SOD more effectively mitigated inflammatory signaling by intracellular superoxide in vitro and in animal models, although total uptake was inferior to that of PECAM-targeted Ab/SOD. Therefore, both geometry and targeting features of Ab/SOD conjugates control delivery to cell surface vs. endosomes for optimal protection against extracellular vs. endosomal oxidative stress, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Size control in the synthesis of 1-6 nm gold nanoparticles via solvent-controlled nucleation.

    Science.gov (United States)

    Song, Jieun; Kim, Dukhan; Lee, Dongil

    2011-11-15

    We report a facile synthetic route for size-controlled preparation of gold nanoparticles. Nearly monodisperse gold nanoparticles with core diameters of 1-6 nm were obtained by reducing AuP(Phenyl)(3)Cl with tert-butylamine borane in the presence of dodecanethiol in the solvent mixture of benzene and CHCl(3). Mechanism studies have shown that the size control is achieved by the solvent-controlled nucleation in which the nuclei concentration increases with increasing the fraction of CHCl(3), leading to smaller particles. It was also found that, following the solvent-controlled nucleation, particle growth occurs via ligand replacement of PPh(3) on the nuclei by Au(I)thiolate generated by the digestive etching of small particles. This synthetic strategy was successfully demonstrated with other alkanethiols of different chain length with which size-controlled, monodisperse gold nanoparticles were prepared in remarkable yield without requiring any postsynthesis treatments.

  5. Cell size is positively correlated between different tissues in passerine birds and amphibians, but not necessarily in mammals

    OpenAIRE

    Kozłowski, J.; Czarnołęski, M.; François-Krassowska, A.; Maciak, S.; Pis, T.

    2010-01-01

    We examined cell size correlations between tissues, and cell size to body mass relationships in passerine birds, amphibians and mammals. The size correlated highly between all cell types in birds and amphibians; mammalian tissues clustered by size correlation in three tissue groups. Erythrocyte size correlated well with the volume of other cell types in birds and amphibians, but poorly in mammals. In birds, body mass correlated positively with the size of all cell types including erythrocytes...

  6. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

    Science.gov (United States)

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-01

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

  7. Sample Size Calculation for Controlling False Discovery Proportion

    Directory of Open Access Journals (Sweden)

    Shulian Shang

    2012-01-01

    Full Text Available The false discovery proportion (FDP, the proportion of incorrect rejections among all rejections, is a direct measure of abundance of false positive findings in multiple testing. Many methods have been proposed to control FDP, but they are too conservative to be useful for power analysis. Study designs for controlling the mean of FDP, which is false discovery rate, have been commonly used. However, there has been little attempt to design study with direct FDP control to achieve certain level of efficiency. We provide a sample size calculation method using the variance formula of the FDP under weak-dependence assumptions to achieve the desired overall power. The relationship between design parameters and sample size is explored. The adequacy of the procedure is assessed by simulation. We illustrate the method using estimated correlations from a prostate cancer dataset.

  8. Measuring bacterial cells size with AFM

    Directory of Open Access Journals (Sweden)

    Denise Osiro

    2012-03-01

    Full Text Available Atomic Force Microscopy (AFM can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe and the bacterium (Escherichia coli JM-109 strain to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described.

  9. Mice divergently selected for high and low basal metabolic rates evolved different cell size and organ mass.

    Science.gov (United States)

    Maciak, S; Bonda-Ostaszewska, E; Czarnołęski, M; Konarzewski, M; Kozłowski, J

    2014-03-01

    Evolution of metabolic rates of multicellular organisms is hypothesized to reflect the evolution of their cell architecture. This is likely to stem from a tight link between the sizes of cells and nuclei, which are expected to be inversely related to cell metabolism. Here, we analysed basal metabolic rate (BMR), internal organ masses and the cell/nucleus size in different tissues of laboratory mice divergently selected for high/low mass-corrected BMR and four random-bred mouse lines. Random-bred lines had intermediate levels of BMR as compared to low- and high-BMR lines. Yet, this pattern was only partly consistent with the between-line differences in cell/nucleus sizes. Erythrocytes and skin epithelium cells were smaller in the high-BMR line than in other lines, but the cells of low-BMR and random-bred mice were similar in size. On the other hand, the size of hepatocytes, kidney proximal tubule cells and duodenum enterocytes were larger in high-BMR mice than other lines. All cell and nucleus sizes were positively correlated, which supports the role of the nucleus in cell size regulation. Our results suggest that the evolution of high BMR involves a reduction in cell size in specialized tissues, whose functions are primarily dictated by surface-to-volume ratios, such as erythrocytes. High BMR may, however, also incur an increase in cell size in tissues with an intense transcription and translation, such as hepatocytes. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  10. Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

    Science.gov (United States)

    Manga, Mohamed S; York, David W

    2017-09-12

    Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

  11. Graphene-Based Flexible Micrometer-Sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.

    2013-10-23

    Microbial fuel cells harvest electrical energy produced by bacteria during the natural decomposition of organic matter. We report a micrometer-sized microbial fuel cell that is able to generate nanowatt-scale power from microliters of liquids. The sustainable design is comprised of a graphene anode, an air cathode, and a polymer-based substrate platform for flexibility. The graphene layer was grown on a nickel thin film by using chemical vapor deposition at atmospheric pressure. Our demonstration provides a low-cost option to generate useful power for lab-on-chip applications and could be promising to rapidly screen and scale up microbial fuel cells for water purification without consuming excessive power (unlike other water treatment technologies).

  12. Detonation cell size measurements and predictions in hydrogen-air-steam mixtures at elevated temperatures

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsberg, T.; Boccio, J.; Economos, C.

    1994-01-01

    The present research reports on the effect of initial mixture temperature on the experimentally measured detonation cell size for hydrogen-air-steam mixtures. Experimental and theoretical research related to combustion phenomena in hydrogen-air-steam mixtures has been ongoing for many years. However, detonation cell size data currently exists or hydrogen-air-steam mixtures up to a temperature of only 400K. Sever accident scenarios have been identified for light water reactors (LWRs) where hydrogen-air mixture temperatures in excess of 400K could be generated within containment. The experiments in this report focus on extending the cell size data base for initial mixture temperatures in excess of 400K. The experiments were carried out in a 10-cm inner-diameter, 6.1-m long heated detonation tube with a maximum operating temperature of 700K and spatial temperature uniformity of ±14K. Detonation cell size measurements provide clear evidence that the effect of hydrogen-air initial gas mixture temperature, in the range 300K--650K, is to decrease cell size and, hence, to increase the sensitivity of the mixture to undergo detonations. The effect of steam content, at any given temperature, is to increase the cell size and, thereby, to decrease the sensitivity of stoichiometric hydrogen-air mixtures. The hydrogen-air detonability limits for the 10-cm inside-diameter test vessel, based upon the onset of single-head spin, decreased from 15 percent by hydrogen at 300K down to about 9 percent hydrogen at 650K. The one-dimensional ZND model does a very good job at predicting the overall trends in the cell size data over the range of hydrogen-air-steam mixture compositions and temperature studied in the experiments

  13. Numerical study on channel size effect for proton exchange membrane fuel cell with serpentine flow field

    International Nuclear Information System (INIS)

    Wang Xiaodong; Yan Weimon; Duan Yuanyuan; Weng Fangbor; Jung Guobin; Lee Chiyuan

    2010-01-01

    This work numerically investigates the effect of the channel size on the cell performance of proton exchange membrane (PEM) fuel cells with serpentine flow fields using a three-dimensional, two-phase model. The local current densities in the PEM, oxygen mass flow rates and liquid water concentrations at the interface of the cathode gas diffusion layer and catalyst layer were analyzed to understand the channel size effect. The predictions show that smaller channel sizes enhance liquid water removal and increase oxygen transport to the porous layers, which improve cell performance. Additionally, smaller channel sizes also provide more uniform current density distributions in the cell. However, as the channel size decreases, the total pressure drops across the cell increases, which leads to more pump work. With taking into account the pressure losses, the optimal cell performance occurs for a cell with a flow channel cross-sectional area of 0.535 x 0.535 mm 2 .

  14. Well-Controlled Cell-Trapping Systems for Investigating Heterogeneous Cell-Cell Interactions.

    Science.gov (United States)

    Kamiya, Koki; Abe, Yuta; Inoue, Kosuke; Osaki, Toshihisa; Kawano, Ryuji; Miki, Norihisa; Takeuchi, Shoji

    2018-03-01

    Microfluidic systems have been developed for patterning single cells to study cell-cell interactions. However, patterning multiple types of cells to understand heterogeneous cell-cell interactions remains difficult. Here, it is aimed to develop a cell-trapping device to assemble multiple types of cells in the well-controlled order and morphology. This device mainly comprises a parylene sheet for assembling cells and a microcomb for controlling the cell-trapping area. The cell-trapping area is controlled by moving the parylene sheet on an SU-8 microcomb using tweezers. Gentle downward flow is used as a driving force for the cell-trapping. The assembly of cells on a parylene sheet with round and line-shaped apertures is demonstrated. The cell-cell contacts of the trapped cells are then investigated by direct cell-cell transfer of calcein via connexin nanopores. Finally, using the device with a system for controlling the cell-trapping area, three different types of cells in the well-controlled order are assembled. The correct cell order rate obtained using the device is 27.9%, which is higher than that obtained without the sliding parylene system (0.74%). Furthermore, the occurrence of cell-cell contact between the three cell types assembled is verified. This cell-patterning device will be a useful tool for investigating heterogeneous cell-cell interactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Comparison of Cell Viability and Embryoid Body Size of Two Embryonic Stem Cell Lines After Different Exposure Times to Bone Morphogenetic Protein 4

    Directory of Open Access Journals (Sweden)

    Nehleh Zarei Fard

    2015-03-01

    Full Text Available Background: Activation of bone morphogenetic protein 4 (BMP4 signaling pathway in embryonic stem (ES cells plays an important role in controlling cell proliferation, differentiation, and apoptosis. Adverse effects of BMP4 occur in a time dependent manner; however, little is known about the effect of different time exposure of this growth factor on cell number in culture media. In this study, we investigated the role of two different exposure times to BMP4 in cell viability, embryoid body (EB, size, and cavitation of ES cells. Methods: Embryonic stem cells (R1 and B1 lines were released from the feeder cell layers and were cultured using EBs protocol by using the hanging drop method and monolayer culture system. The cells were cultured for 5 days with 100 ng/mL BMP4 from the beginning (++BMP4 or after 48 h (+BMP4 of culture and their cell number were counted by trypan blue staining. The data were analyzed using non-parametric two-tailed Mann-Whitney test. P<0.05 was considered as significant. Results: In EB culture protocol, cell number significantly decreased in +BMP4 culture condition with greater cavity size compared to the ++BMP4 condition at day 5 (P=0.009. In contrast, in monolayer culture system, there was no significant difference in the cell number between all groups (P=0.91. Conclusion: The results suggest that short-term exposure of BMP4 is required to promote cavitation in EBs according to lower cell number in +BMP4 condition. Different cell lines showed different behavior in cavitation formation.

  16. Big or fast: two strategies in the developmental control of body size

    OpenAIRE

    Nijhout, H. Frederik

    2015-01-01

    Adult body size is controlled by the mechanisms that stop growth when a species-characteristic size has been reached. The mechanisms by which size is sensed and by which this information is transduced to the growth regulating system are beginning to be understood in a few species of insects. Two rather different strategies for control have been discovered; one favors large body size and the other favors rapid development.

  17. 2D and 3D Stem Cell Models of Primate Cortical Development Identify Species-Specific Differences in Progenitor Behavior Contributing to Brain Size.

    Science.gov (United States)

    Otani, Tomoki; Marchetto, Maria C; Gage, Fred H; Simons, Benjamin D; Livesey, Frederick J

    2016-04-07

    Variation in cerebral cortex size and complexity is thought to contribute to differences in cognitive ability between humans and other animals. Here we compare cortical progenitor cell output in humans and three nonhuman primates using directed differentiation of pluripotent stem cells (PSCs) in adherent two-dimensional (2D) and organoid three-dimensional (3D) culture systems. Clonal lineage analysis showed that primate cortical progenitors proliferate for a protracted period of time, during which they generate early-born neurons, in contrast to rodents, where this expansion phase largely ceases before neurogenesis begins. The extent of this additional cortical progenitor expansion differs among primates, leading to differences in the number of neurons generated by each progenitor cell. We found that this mechanism for controlling cortical size is regulated cell autonomously in culture, suggesting that primate cerebral cortex size is regulated at least in part at the level of individual cortical progenitor cell clonal output. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  18. The Hippo pathway controls border cell migration through distinct mechanisms in outer border cells and polar cells of the Drosophila ovary.

    Science.gov (United States)

    Lin, Tzu-Huai; Yeh, Tsung-Han; Wang, Tsu-Wei; Yu, Jenn-Yah

    2014-11-01

    The Hippo pathway is a key signaling cascade in controlling organ size. The core components of this pathway are two kinases, Hippo (Hpo) and Warts (Wts), and a transcriptional coactivator, Yorkie (Yki). Yes-associated protein (YAP, a Yki homolog in mammals) promotes epithelial-mesenchymal transition and cell migration in vitro. Here, we use border cells in the Drosophila ovary as a model to study Hippo pathway functions in cell migration in vivo. During oogenesis, polar cells secrete Unpaired (Upd), which activates JAK/STAT signaling of neighboring cells and specifies them into outer border cells. The outer border cells form a cluster with polar cells and undergo migration. We find that hpo and wts are required for migration of the border cell cluster. In outer border cells, overexpression of hpo disrupts polarization of the actin cytoskeleton and attenuates migration. In polar cells, knockdown of hpo and wts or overexpression of yki impairs border cell induction and disrupts migration. These manipulations in polar cells reduce JAK/STAT activity in outer border cells. Expression of upd-lacZ is increased and decreased in yki and hpo mutant polar cells, respectively. Furthermore, forced expression of upd in polar cells rescues defects of border cell induction and migration caused by wts knockdown. These results suggest that Yki negatively regulates border cell induction by inhibiting JAK/STAT signaling. Together, our data elucidate two distinct mechanisms of the Hippo pathway in controlling border cell migration: (1) in outer border cells, it regulates polarized distribution of the actin cytoskeleton; (2) in polar cells, it regulates upd expression to control border cell induction and migration. Copyright © 2014 by the Genetics Society of America.

  19. Size-dependent electronic structure controls activity for ethanol electro-oxidation at Ptn/indium tin oxide (n = 1 to 14).

    Science.gov (United States)

    von Weber, Alexander; Baxter, Eric T; Proch, Sebastian; Kane, Matthew D; Rosenfelder, Michael; White, Henry S; Anderson, Scott L

    2015-07-21

    Understanding the factors that control electrochemical catalysis is essential to improving performance. We report a study of electrocatalytic ethanol oxidation - a process important for direct ethanol fuel cells - over size-selected Pt centers ranging from single atoms to Pt14. Model electrodes were prepared by soft-landing of mass-selected Ptn(+) on indium tin oxide (ITO) supports in ultrahigh vacuum, and transferred to an in situ electrochemical cell without exposure to air. Each electrode had identical Pt coverage, and differed only in the size of Pt clusters deposited. The small Ptn have activities that vary strongly, and non-monotonically with deposited size. Activity per gram Pt ranges up to ten times higher than that of 5 to 10 nm Pt particles dispersed on ITO. Activity is anti-correlated with the Pt 4d core orbital binding energy, indicating that electron rich clusters are essential for high activity.

  20. Improved genome recovery and integrated cell-size analyses of individual uncultured microbial cells and viral particles.

    Science.gov (United States)

    Stepanauskas, Ramunas; Fergusson, Elizabeth A; Brown, Joseph; Poulton, Nicole J; Tupper, Ben; Labonté, Jessica M; Becraft, Eric D; Brown, Julia M; Pachiadaki, Maria G; Povilaitis, Tadas; Thompson, Brian P; Mascena, Corianna J; Bellows, Wendy K; Lubys, Arvydas

    2017-07-20

    Microbial single-cell genomics can be used to provide insights into the metabolic potential, interactions, and evolution of uncultured microorganisms. Here we present WGA-X, a method based on multiple displacement amplification of DNA that utilizes a thermostable mutant of the phi29 polymerase. WGA-X enhances genome recovery from individual microbial cells and viral particles while maintaining ease of use and scalability. The greatest improvements are observed when amplifying high G+C content templates, such as those belonging to the predominant bacteria in agricultural soils. By integrating WGA-X with calibrated index-cell sorting and high-throughput genomic sequencing, we are able to analyze genomic sequences and cell sizes of hundreds of individual, uncultured bacteria, archaea, protists, and viral particles, obtained directly from marine and soil samples, in a single experiment. This approach may find diverse applications in microbiology and in biomedical and forensic studies of humans and other multicellular organisms.Single-cell genomics can be used to study uncultured microorganisms. Here, Stepanauskas et al. present a method combining improved multiple displacement amplification and FACS, to obtain genomic sequences and cell size information from uncultivated microbial cells and viral particles in environmental samples.

  1. Contact behavior modelling and its size effect on proton exchange membrane fuel cell

    Science.gov (United States)

    Qiu, Diankai; Peng, Linfa; Yi, Peiyun; Lai, Xinmin; Janßen, Holger; Lehnert, Werner

    2017-10-01

    Contact behavior between the gas diffusion layer (GDL) and bipolar plate (BPP) is of significant importance for proton exchange membrane fuel cells. Most current studies on contact behavior utilize experiments and finite element modelling and focus on fuel cells with graphite BPPs, which lead to high costs and huge computational requirements. The objective of this work is to build a more effective analytical method for contact behavior in fuel cells and investigate the size effect resulting from configuration alteration of channel and rib (channel/rib). Firstly, a mathematical description of channel/rib geometry is outlined in accordance with the fabrication of metallic BPP. Based on the interface deformation characteristic and Winkler surface model, contact pressure between BPP and GDL is then calculated to predict contact resistance and GDL porosity as evaluative parameters of contact behavior. Then, experiments on BPP fabrication and contact resistance measurement are conducted to validate the model. The measured results demonstrate an obvious dependence on channel/rib size. Feasibility of the model used in graphite fuel cells is also discussed. Finally, size factor is proposed for evaluating the rule of size effect. Significant increase occurs in contact resistance and porosity for higher size factor, in which channel/rib width decrease.

  2. Advanced Attitude Control af Pico Sized Satellites

    DEFF Research Database (Denmark)

    Larsen, Jesper A.; Amini, Rouzbeh; Izadi-Zamanabadi, Roozbeh

    2005-01-01

    accuracy of better than 5 degrees. Cost, size, weight and power requirements, on the other hand, impose selecting relative simple sensors and actuators which leads to an attitude control requirement of less than 1 degree. This precision is obtained by a combination of magnetorquers and momentum wheels...

  3. Empirical evidence for multi-scaled controls on wildfire size distributions in California

    Science.gov (United States)

    Povak, N.; Hessburg, P. F., Sr.; Salter, R. B.

    2014-12-01

    Ecological theory asserts that regional wildfire size distributions are examples of self-organized critical (SOC) systems. Controls on SOC event-size distributions by virtue are purely endogenous to the system and include the (1) frequency and pattern of ignitions, (2) distribution and size of prior fires, and (3) lagged successional patterns after fires. However, recent work has shown that the largest wildfires often result from extreme climatic events, and that patterns of vegetation and topography may help constrain local fire spread, calling into question the SOC model's simplicity. Using an atlas of >12,000 California wildfires (1950-2012) and maximum likelihood estimation (MLE), we fit four different power-law models and broken-stick regressions to fire-size distributions across 16 Bailey's ecoregions. Comparisons among empirical fire size distributions across ecoregions indicated that most ecoregion's fire-size distributions were significantly different, suggesting that broad-scale top-down controls differed among ecoregions. One-parameter power-law models consistently fit a middle range of fire sizes (~100 to 10000 ha) across most ecoregions, but did not fit to larger and smaller fire sizes. We fit the same four power-law models to patch size distributions of aspect, slope, and curvature topographies and found that the power-law models fit to a similar middle range of topography patch sizes. These results suggested that empirical evidence may exist for topographic controls on fire sizes. To test this, we used neutral landscape modeling techniques to determine if observed fire edges corresponded with aspect breaks more often than expected by random. We found significant differences between the empirical and neutral models for some ecoregions, particularly within the middle range of fire sizes. Our results, combined with other recent work, suggest that controls on ecoregional fire size distributions are multi-scaled and likely are not purely SOC. California

  4. Gold nanoparticle size and shape influence on osteogenesis of mesenchymal stem cells

    Science.gov (United States)

    Li, Jingchao; Li, Jia'en Jasmine; Zhang, Jing; Wang, Xinlong; Kawazoe, Naoki; Chen, Guoping

    2016-04-01

    Gold nanoparticles (AuNPs) have been extensively explored for biomedical applications due to their advantages of facile synthesis and surface functionalization. Previous studies have suggested that AuNPs can induce differentiation of stem cells into osteoblasts. However, how the size and shape of AuNPs affect the differentiation response of stem cells has not been elucidated. In this work, a series of bovine serum albumin (BSA)-coated Au nanospheres, Au nanostars and Au nanorods with different diameters of 40, 70 and 110 nm were synthesized and their effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) were investigated. All the AuNPs showed good cytocompatibility and did not influence proliferation of hMSCs at the studied concentrations. Osteogenic differentiation of hMSCs was dependent on the size and shape of AuNPs. Sphere-40, sphere-70 and rod-70 significantly increased the alkaline phosphatase (ALP) activity and calcium deposition of cells while rod-40 reduced the ALP activity and calcium deposition. Gene profiling revealed that the expression of osteogenic marker genes was down-regulated after incubation with rod-40. However, up-regulation of these genes was found in the sphere-40, sphere-70 and rod-70 treatment. Moreover, it was found that the size and shape of AuNPs affected the osteogenic differentiation of hMSCs through regulating the activation of Yes-associated protein (YAP). These results indicate that the size and shape of AuNPs had an influence on the osteogenic differentiation of hMSCs, which should provide useful guidance for the preparation of AuNPs with defined size and shape for their biomedical applications.Gold nanoparticles (AuNPs) have been extensively explored for biomedical applications due to their advantages of facile synthesis and surface functionalization. Previous studies have suggested that AuNPs can induce differentiation of stem cells into osteoblasts. However, how the size and shape of AuNPs affect the

  5. Synthesis of SAPO-56 with controlled crystal size

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ting; Feng, Xuhui [Colorado School of Mines, Chemical and Biological Engineering Department (United States); Carreon, Maria L. [University of Tulsa, Rusell School of Chemical Engineering (United States); Carreon, Moises A., E-mail: mcarreon@mines.edu [Colorado School of Mines, Chemical and Biological Engineering Department (United States)

    2017-03-15

    Herein, we present the hydrothermal synthesis of SAPO-56 crystals with relatively controlled crystal/particle size. The effects of water content, aluminum source, gel composition, stirring, crystallization temperature and time, as well as the incorporation of crystal growth inhibitors during synthesis were systematically investigated. The synthesized SAPO-56 crystals displayed BET surface areas as high as ∼630 m{sup 2} g{sup −1} with relative narrow size distribution in the ∼5–60 μm range. Nitrogen BET surface areas in the 451 to 631 m{sup 2} g{sup −1} range were observed. Decreasing the crystallization temperature from 220 to 210 °C helped to decrease the average SAPO-56 crystal size. Diluted gel compositions promoted the formation of smaller crystals. Crystal growth inhibitors were found to be helpful in reducing crystal size and narrow the size distribution. Specifically, ∼5 μm SAPO-56 crystals displaying narrow size distribution were synthesized employing aluminum-tri-sec-butoxide as Al source, high water content, and high stirring rates.

  6. Synthesis of SAPO-56 with controlled crystal size

    International Nuclear Information System (INIS)

    Wu, Ting; Feng, Xuhui; Carreon, Maria L.; Carreon, Moises A.

    2017-01-01

    Herein, we present the hydrothermal synthesis of SAPO-56 crystals with relatively controlled crystal/particle size. The effects of water content, aluminum source, gel composition, stirring, crystallization temperature and time, as well as the incorporation of crystal growth inhibitors during synthesis were systematically investigated. The synthesized SAPO-56 crystals displayed BET surface areas as high as ∼630 m"2 g"−"1 with relative narrow size distribution in the ∼5–60 μm range. Nitrogen BET surface areas in the 451 to 631 m"2 g"−"1 range were observed. Decreasing the crystallization temperature from 220 to 210 °C helped to decrease the average SAPO-56 crystal size. Diluted gel compositions promoted the formation of smaller crystals. Crystal growth inhibitors were found to be helpful in reducing crystal size and narrow the size distribution. Specifically, ∼5 μm SAPO-56 crystals displaying narrow size distribution were synthesized employing aluminum-tri-sec-butoxide as Al source, high water content, and high stirring rates.

  7. Genome size evolution in Ontario ferns (Polypodiidae): evolutionary correlations with cell size, spore size, and habitat type and an absence of genome downsizing.

    Science.gov (United States)

    Henry, Thomas A; Bainard, Jillian D; Newmaster, Steven G

    2014-10-01

    Genome size is known to correlate with a number of traits in angiosperms, but less is known about the phenotypic correlates of genome size in ferns. We explored genome size variation in relation to a suite of morphological and ecological traits in ferns. Thirty-six fern taxa were collected from wild populations in Ontario, Canada. 2C DNA content was measured using flow cytometry. We tested for genome downsizing following polyploidy using a phylogenetic comparative analysis to explore the correlation between 1Cx DNA content and ploidy. There was no compelling evidence for the occurrence of widespread genome downsizing during the evolution of Ontario ferns. The relationship between genome size and 11 morphological and ecological traits was explored using a phylogenetic principal component regression analysis. Genome size was found to be significantly associated with cell size, spore size, spore type, and habitat type. These results are timely as past and recent studies have found conflicting support for the association between ploidy/genome size and spore size in fern polyploid complexes; this study represents the first comparative analysis of the trend across a broad taxonomic group of ferns.

  8. Control valve sizing and specification: The first step

    International Nuclear Information System (INIS)

    Harkins, J.F.; Hoyle, E.D.

    1991-01-01

    Today's modern control valve can satisfy almost any application. Special trim, materials, operators, and body configurations have been developed to meet the most severe operating conditions. The missing link in the chain connecting design to application is often the interpretation and communication of the requirements for determining the proper valve for each application. This paper addresses an important but often neglected requirement for proper selection and sizing of control valves: the determination of correct input data. It presents criteria necessary to ensure that the data given the manufacturer accurately reflects the conditions under which the control valve will operate. It highlights the importance of communication between the system design engineer, the valve specifying engineer, and the control valve supplier, to ensure that the final system design meets the true requirements of the application. An example is provided of a simple liquid-handling system, for which line losses and variations in flow and equipment capacities are tabulated and requirements shown graphically on typical control valve characteristic curves. The effects of seemingly harmless, conservative assumptions regarding line losses, equipment capacities and selection, sizing practices, and the selection of various flow data can have on the final valve selection are illustrated. Also discussed is the proper selection of equipment and input data, based on the example

  9. Evaluation of growth, cell size and biomass of Isochrysis aff. galbana (T-ISO with two LED regimes

    Directory of Open Access Journals (Sweden)

    Miguel Victor Cordoba-Matson

    2013-04-01

    Full Text Available In contrast to crops, there are fewer studies using LED-based light with green microalgae and none cultivating the microalga Isochrysis aff. galbana (T-ISO even though of its importance in marine aquaculture. The objective was to evaluate of white and red LEDs as an alternative source of light to cultivate I. aff. galbana (T-ISO. In order to carry this out white and red LEDs were used with a laboratory built Erlenmeyer-type photobioreactor to determine productivity, cell number and size and biomass composition. Results were compared with standard fluorescent lights of the same light intensity. The culture system consisted of 3 flasks for applying red LEDs and three for white LEDs and 3 control group flasks illuminated with the normal fluorescent lighting at the similar light intensity of ~60 mM m–2 s–1. It was found that the population cell density did not significantly increase with either red LEDs or white LEDs (p > 0.05, if at all. Standard fluorescent lighting (control group showed significant increases in population cell number (p < 0.05. Through microscopic observation cell size was found to be smaller for white LEDS and even smaller for red LEDs compared to fluorescent lighting. Biochemical composition of proteins, carbohydrates and lipids was similar for all light regimes. The authors suggest that the unexpected non-growth I. aff. galbana (T-ISO, a haptophyte microalga, with white and red LEDs is possibly due to fact that to initiate cell growth this microalgae requires other wavelengths (possibly green besides red and blue, to allow other pigments, probably fucoxanthin, to capture light

  10. Size-controlled synthesis of nickel nanoparticles

    International Nuclear Information System (INIS)

    Hou, Y.; Kondoh, H.; Ohta, T.; Gao, S.

    2005-01-01

    A facile reduction approach with nickel acetylacetonate, Ni(acac) 2 , and sodium borohydride or superhydride leads to monodisperse nickel nanoparticles in the presence of hexadecylamine (HDA) and trioctylphosphine oxide (TOPO). The combination of HDA and TOPO used in the conventional synthesis of semiconductor nanocrystals also provides better control over particle growth in the metal nanoparticle synthesis. The size of Ni nanoparticles can be readily tuned from 3 to 11 nm, depending on the ratio of HDA to TOPO in the reaction system. As-synthesized Ni nanoparticles have a cubic structure as characterized by power X-ray diffraction (XRD), selected-area electron diffraction (SAED). Transmission electron microscopy (TEM) images show that Ni nanoparticles have narrow size distribution. SQUID magnetometry was also used in the characterization of Ni nanoparticles. The synthetic procedure can be extended to the preparation of high quality metal or alloy nanoparticles

  11. Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

    Science.gov (United States)

    Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

    2017-10-14

    Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Rapid formation of size-controllable multicellular spheroids via 3D acoustic tweezers.

    Science.gov (United States)

    Chen, Kejie; Wu, Mengxi; Guo, Feng; Li, Peng; Chan, Chung Yu; Mao, Zhangming; Li, Sixing; Ren, Liqiang; Zhang, Rui; Huang, Tony Jun

    2016-07-05

    The multicellular spheroid is an important 3D cell culture model for drug screening, tissue engineering, and fundamental biological research. Although several spheroid formation methods have been reported, the field still lacks high-throughput and simple fabrication methods to accelerate its adoption in drug development industry. Surface acoustic wave (SAW) based cell manipulation methods, which are known to be non-invasive, flexible, and high-throughput, have not been successfully developed for fabricating 3D cell assemblies or spheroids, due to the limited understanding on SAW-based vertical levitation. In this work, we demonstrated the capability of fabricating multicellular spheroids in the 3D acoustic tweezers platform. Our method used drag force from microstreaming to levitate cells in the vertical direction, and used radiation force from Gor'kov potential to aggregate cells in the horizontal plane. After optimizing the device geometry and input power, we demonstrated the rapid and high-throughput nature of our method by continuously fabricating more than 150 size-controllable spheroids and transferring them to Petri dishes every 30 minutes. The spheroids fabricated by our 3D acoustic tweezers can be cultured for a week with good cell viability. We further demonstrated that spheroids fabricated by this method could be used for drug testing. Unlike the 2D monolayer model, HepG2 spheroids fabricated by the 3D acoustic tweezers manifested distinct drug resistance, which matched existing reports. The 3D acoustic tweezers based method can serve as a novel bio-manufacturing tool to fabricate complex 3D cell assembles for biological research, tissue engineering, and drug development.

  13. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

    Directory of Open Access Journals (Sweden)

    Filová E

    2014-08-01

    Full Text Available Elena Filová,1 Tomáš Suchý,2,3 Zbynek Sucharda,2 Monika Šupová,2 Margit Žaloudková,2 Karel Balík,2 Vera Lisá,1 Miroslav Šlouf,4 Lucie Bacáková11Department of Biomaterials and Tissue Engineering, Institute of Physiology, 2Department of Composite and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, 3Laboratory of Biomechanics, Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, CTU in Prague, 4Department of Morphology and Rheology of Polymer Materials, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech RepublicAbstract: Hydroxyapatite (HA is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N or micro-sized (M HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v (referred to as N0–N25 or M0–M25, and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%, MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v nano-size or micro-size HA seems to be optimum

  14. Size Controlled Synthesis of Transition Metal Nanoparticles for Catalytic Applications

    KAUST Repository

    Esparza, Angel

    2011-07-07

    Catalysis offers cleaner and more efficient chemical reactions for environmental scientists. More than 90% of industrial processes are performed with a catalyst involved, however research it is still required to improve the catalyst materials. The purpose of this work is to contribute with the development of catalysts synthesis with two different approaches. First, the precise size control of non-noble metals nanoparticles. Second, a new one-pot synthesis method based on a microemulsion system was developed to synthesize size-controlled metal nanoparticles in oxide supports. The one-pot method represents a simple approach to synthesize both support and immobilized nanometer-sized non-noble metal nanoparticles in the same reaction system. Narrow size distribution nickel, cobalt, iron and cobalt-nickel nanoparticles were obtained. High metal dispersions are attainable regardless the metal or support used in the synthesis. Thus, the methodology is adaptable and robust. The sizecontrolled supported metal nanoparticles offer the opportunity to study size effects and metal-support interactions on different catalytic reactions with different sets of metals and supports.

  15. Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

    Science.gov (United States)

    Weber, Stephanie C; Brangwynne, Clifford P

    2015-03-02

    Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Ultrasound Assisted Particle Size Control by Continuous Seed Generation and Batch Growth

    OpenAIRE

    Jordens, Jeroen; Canini, Enio; Gielen, Bjorn; Van Gerven, Tom; Braeken, Leen

    2017-01-01

    Controlling particle size is essential for crystal quality in the chemical and pharmaceutical industry. Several articles illustrate the potential of ultrasound to tune this particle size during the crystallization process. This paper investigates how ultrasound can control the particle size distribution (PSD) of acetaminophen crystals by continuous seed generation in a tubular crystallizer followed by batch growth. It is demonstrated that the supersaturation ratio at which ultrasound starts s...

  17. Size variability of the unit building block of peripheral light-harvesting antennas as a strategy for effective functioning of antennas of variable size that is controlled in vivo by light intensity.

    Science.gov (United States)

    Taisova, A S; Yakovlev, A G; Fetisova, Z G

    2014-03-01

    This work continuous a series of studies devoted to discovering principles of organization of natural antennas in photosynthetic microorganisms that generate in vivo large and highly effective light-harvesting structures. The largest antenna is observed in green photosynthesizing bacteria, which are able to grow over a wide range of light intensities and adapt to low intensities by increasing of size of peripheral BChl c/d/e antenna. However, increasing antenna size must inevitably cause structural changes needed to maintain high efficiency of its functioning. Our model calculations have demonstrated that aggregation of the light-harvesting antenna pigments represents one of the universal structural factors that optimize functioning of any antenna and manage antenna efficiency. If the degree of aggregation of antenna pigments is a variable parameter, then efficiency of the antenna increases with increasing size of a single aggregate of the antenna. This means that change in degree of pigment aggregation controlled by light-harvesting antenna size is biologically expedient. We showed in our previous work on the oligomeric chlorosomal BChl c superantenna of green bacteria of the Chloroflexaceae family that this principle of optimization of variable antenna structure, whose size is controlled by light intensity during growth of bacteria, is actually realized in vivo. Studies of this phenomenon are continued in the present work, expanding the number of studied biological materials and investigating optical linear and nonlinear spectra of chlorosomes having different structures. We show for oligomeric chlorosomal superantennas of green bacteria (from two different families, Chloroflexaceae and Oscillochloridaceae) that a single BChl c aggregate is of small size, and the degree of BChl c aggregation is a variable parameter, which is controlled by the size of the entire BChl c superantenna, and the latter, in turn, is controlled by light intensity in the course of cell

  18. Maternal retinoids control type 3 innate lymphoid cells and set the offspring immunity

    Science.gov (United States)

    van de Pavert, Serge A.; Ferreira, Manuela; Domingues, Rita G.; Ribeiro, Hélder; Molenaar, Rosalie; Moreira-Santos, Lara; Almeida, Francisca F.; Ibiza, Sales; Barbosa, Inês; Goverse, Gera; Labão-Almeida, Carlos; Godinho-Silva, Cristina; Konijn, Tanja; Schooneman, Dennis; O'Toole, Tom; Mizee, Mark R.; Habani, Yasmin; Haak, Esther; Santori, Fabio R.; Littman, Dan R.; Schulte-Merker, Stefan; Dzierzak, Elaine; Simas, J. Pedro; Mebius, Reina E.; Veiga-Fernandes, Henrique

    2014-04-01

    The impact of nutritional status during fetal life on the overall health of adults has been recognized; however, dietary effects on the developing immune system are largely unknown. Development of secondary lymphoid organs occurs during embryogenesis and is considered to be developmentally programmed. Secondary lymphoid organ formation depends on a subset of type 3 innate lymphoid cells (ILC3) named lymphoid tissue inducer (LTi) cells. Here we show that mouse fetal ILC3s are controlled by cell-autonomous retinoic acid (RA) signalling in utero, which pre-sets the immune fitness in adulthood. We found that embryonic lymphoid organs contain ILC progenitors that differentiate locally into mature LTi cells. Local LTi cell differentiation was controlled by maternal retinoid intake and fetal RA signalling acting in a haematopoietic cell-autonomous manner. RA controlled LTi cell maturation upstream of the transcription factor RORγt. Accordingly, enforced expression of Rorgt restored maturation of LTi cells with impaired RA signalling, whereas RA receptors directly regulated the Rorgt locus. Finally, we established that maternal levels of dietary retinoids control the size of secondary lymphoid organs and the efficiency of immune responses in the adult offspring. Our results reveal a molecular link between maternal nutrients and the formation of immune structures required for resistance to infection in the offspring.

  19. Simultaneous control of nanocrystal size and nanocrystal ...

    Indian Academy of Sciences (India)

    applications such as a photo-sensor [11]. Thus, it is desirable to have, not only a control on the size of the nanocrystals, but also an independent tunability of the ... 1-thioglycerol) in 25 ml methanol under inert atmosphere. 10 ml of 0.2 M sodium sulfide solution is then added to the reaction mixture dropwise and the reaction.

  20. Ontogeny of metabolic rate and red blood cell size in eyelid geckos: species follow different paths.

    Directory of Open Access Journals (Sweden)

    Zuzana Starostová

    Full Text Available While metabolism is a fundamental feature of all organisms, the causes of its scaling with body mass are not yet fully explained. Nevertheless, observations of negative correlations between red blood cell (RBC size and the rate of metabolism suggest that size variation of these cells responsible for oxygen supply may play a crucial role in determining metabolic rate scaling in vertebrates. Based on a prediction derived from the Cell Metabolism Hypothesis, metabolic rate should increase linearly with body mass in species with RBC size invariance, and slower than linearly when RBC size increases with body mass. We found support for that prediction in five species of eyelid geckos (family Eublepharidae with different patterns of RBC size variation during ontogenetic growth. During ontogeny, metabolic rate increases nearly linearly with body mass in those species of eyelid geckos where there is no correlation between RBC size and body mass, whereas non-linearity of metabolic rate scaling is evident in those species with ontogenetic increase of RBC size. Our findings provide evidence that ontogenetic variability in RBC size, possibly correlating with sizes of other cell types, could have important physiological consequences and can contribute to qualitatively different shape of the intraspecific relationship between metabolic rate and body mass.

  1. Ontogeny of metabolic rate and red blood cell size in eyelid geckos: species follow different paths.

    Science.gov (United States)

    Starostová, Zuzana; Konarzewski, Marek; Kozłowski, Jan; Kratochvíl, Lukáš

    2013-01-01

    While metabolism is a fundamental feature of all organisms, the causes of its scaling with body mass are not yet fully explained. Nevertheless, observations of negative correlations between red blood cell (RBC) size and the rate of metabolism suggest that size variation of these cells responsible for oxygen supply may play a crucial role in determining metabolic rate scaling in vertebrates. Based on a prediction derived from the Cell Metabolism Hypothesis, metabolic rate should increase linearly with body mass in species with RBC size invariance, and slower than linearly when RBC size increases with body mass. We found support for that prediction in five species of eyelid geckos (family Eublepharidae) with different patterns of RBC size variation during ontogenetic growth. During ontogeny, metabolic rate increases nearly linearly with body mass in those species of eyelid geckos where there is no correlation between RBC size and body mass, whereas non-linearity of metabolic rate scaling is evident in those species with ontogenetic increase of RBC size. Our findings provide evidence that ontogenetic variability in RBC size, possibly correlating with sizes of other cell types, could have important physiological consequences and can contribute to qualitatively different shape of the intraspecific relationship between metabolic rate and body mass.

  2. Coordination of size-control, reproduction and generational memory in freshwater planarians

    Science.gov (United States)

    Yang, Xingbo; Kaj, Kelson J.; Schwab, David J.; Collins, Eva-Maria S.

    2017-06-01

    Uncovering the mechanisms that control size, growth, and division rates of organisms reproducing through binary division means understanding basic principles of their life cycle. Recent work has focused on how division rates are regulated in bacteria and yeast, but this question has not yet been addressed in more complex, multicellular organisms. We have, over the course of several years, assembled a unique large-scale data set on the growth and asexual reproduction of two freshwater planarian species, Dugesia japonica and Girardia tigrina, which reproduce by transverse fission and succeeding regeneration of head and tail pieces into new planarians. We show that generation-dependent memory effects in planarian reproduction need to be taken into account to accurately capture the experimental data. To achieve this, we developed a new additive model that mixes multiple size control strategies based on planarian size, growth, and time between divisions. Our model quantifies the proportions of each strategy in the mixed dynamics, revealing the ability of the two planarian species to utilize different strategies in a coordinated manner for size control. Additionally, we found that head and tail offspring of both species employ different mechanisms to monitor and trigger their reproduction cycles. Thus, we find a diversity of strategies not only between species but between heads and tails within species. Our additive model provides two advantages over existing 2D models that fit a multivariable splitting rate function to the data for size control: firstly, it can be fit to relatively small data sets and can thus be applied to systems where available data is limited. Secondly, it enables new biological insights because it explicitly shows the contributions of different size control strategies for each offspring type.

  3. Size control of Au NPs supported by pH operation

    Science.gov (United States)

    Ichiji, Masumi; Akiba, Hiroko; Hirasawa, Izumi

    2017-07-01

    Au NPs are expected to become useful functional particles, as particle gun used for plant gene transfer and also catalysts. We have studied PSD (particle size distribution) control of Au NPs by reduction crystallization. Previous study found out importance of seeds policy and also feeding profile. In this paper, effect of pH in the reduction crystallization was investigated to clarify the possibility of Au NPs PSD control by pH operation and also their growth process. Au NPs of size range 10-600 nm were obtained in single-jet system using ascorbic acid (AsA) as a reducing agent with adjusting pH of AsA. Au NPs are found to grow in the process of nucleation, agglomeration, agglomeration growth and surface growth. Au NPs tend to grow by agglomeration and become larger size in lower pH regions, and to grow only by surface growth and become smaller size in higher pH regions.

  4. Nutritional effects of culture media on mycoplasma cell size and removal by filtration.

    Science.gov (United States)

    Folmsbee, Martha; Howard, Glenn; McAlister, Morven

    2010-03-01

    Careful media filtration prior to use is an important part of a mycoplasma contamination prevention program. This study was conducted to increase our knowledge of factors that influence efficient filtration of mycoplasma. The cell size of Acholeplasma laidlawii was measured after culture in various nutritional conditions using scanning electron microscopy. The maximum cell size changed, but the minimum cell size remained virtually unchanged and all tested nutritional conditions resulted in a population of cells smaller than 0.2 microm. Culture in Tryptic Soy Broth (TSB) resulted in an apparent increase in the percentage of very small cells which was not reflected in increased penetration of non-retentive 0.2 microm rated filters. A. laidlawii cultured in selected media formulations was used to challenge 0.2 microm rated filters using mycoplasma broth base as the carrier fluid. We used 0.2 microm rated filters as an analytical tool because A. laidlawii is known to penetrate 0.2 microm filters and the degrees of penetration can be compared. Culture of A. laidlawii in TSB resulted in cells that did not penetrate 0.2 microm rated filters to the same degree as cells cultured in other media such as mycoplasma broth or in TSB supplemented with 10% horse serum. (c) 2009 The International Association for Biologicals. Published by Elsevier Ltd. All rights reserved.

  5. Size-controlled synthesis of biodegradable nanocarriers for targeted ...

    Indian Academy of Sciences (India)

    Research for synthesis of size-controlled carriers is currently challenging one. In this research paper, a ... There are many methods available for the prepara- tion of drug-loaded ... 2.3 Characterization of nanoparticles. 2.3a FT-IR spectral ...

  6. Mercury induces proliferation and reduces cell size in vascular smooth muscle cells through MAPK, oxidative stress and cyclooxygenase-2 pathways

    Energy Technology Data Exchange (ETDEWEB)

    Aguado, Andrea; Galán, María; Zhenyukh, Olha; Wiggers, Giulia A.; Roque, Fernanda R. [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); Redondo, Santiago [Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Peçanha, Franck [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); Martín, Angela [Departamento de Bioquímica, Fisiología y Genética Molecular, Universidad Rey Juan Carlos, 28922, Alcorcón (Spain); Fortuño, Ana [Área de Ciencias Cardiovasculares, Centro de Investigación Médica Aplicada, Universidad de Navarra, 31008, Pamplona (Spain); Cachofeiro, Victoria [Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Tejerina, Teresa [Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Salaices, Mercedes, E-mail: mercedes.salaices@uam.es [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); and others

    2013-04-15

    Mercury exposure is known to increase cardiovascular risk but the underlying cellular mechanisms remain undetermined. We analyzed whether chronic exposure to HgCl{sub 2} affects vascular structure and the functional properties of vascular smooth muscle cells (VSMC) through oxidative stress/cyclooxygenase-2 dependent pathways. Mesenteric resistance arteries and aortas from Wistar rats treated with HgCl{sub 2} (first dose 4.6 mg kg{sup −1}, subsequent doses 0.07 mg kg{sup −1} day{sup −1}, 30 days) and cultured aortic VSMC stimulated with HgCl{sub 2} (0.05–5 μg/ml) were used. Treatment of rats with HgCl{sub 2} decreased wall thickness of the resistance and conductance vasculature, increased the number of SMC within the media and decreased SMC nucleus size. In VSMCs, exposure to HgCl{sub 2}: 1) induced a proliferative response and a reduction in cell size; 2) increased superoxide anion production, NADPH oxidase activity, gene and/or protein levels of the NADPH oxidase subunit NOX-1, the EC- and Mn-superoxide dismutases and cyclooxygenase-2 (COX-2); 3) induced activation of ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized the proliferative response and the altered cell size induced by HgCl{sub 2}. Blockade of ERK1/2 and p38 signaling pathways abolished the HgCl{sub 2}-induced Nox1 and COX-2 expression and normalized the alterations induced by mercury in cell proliferation and size. In conclusion, long exposure of VSMC to low doses of mercury activates MAPK signaling pathways that result in activation of inflammatory proteins such as NADPH oxidase and COX-2 that in turn induce proliferation of VSMC and changes in cell size. These findings offer further evidence that mercury might be considered an environmental risk factor for cardiovascular disease. - Highlights: ► Chronic HgCl{sub 2} exposure induces vascular remodeling. ► HgCl{sub 2} induces proliferation and decreased cell size in vascular smooth muscle cells. ► HgCl{sub 2} induces

  7. Cell size spatial convergence analysis on GOTHIC distributed parameter models for studying hydrogen mixing behaviour in CANDU containments

    International Nuclear Information System (INIS)

    Yim, K.; Wong, R.C.

    1995-01-01

    Gas mixing phenomena can be modelled using distributed parameter codes such as GOTHIC, but the selection of the optimum cell size is an important user input. The tradeoff between accuracy and practical computation times affect the choice of cell sizes, where small cells provide better accuracy at the expense of longer computing time. A study on cell size effect on hydrogen distribution is presented for the problem of hydrogen mixing behaviour in a typical CANDU reactor containment following a severe reactor accident. Optimal cell sizes were found for different room volumes, hydrogen release profiles and elevations using spatial convergence criteria. The findings of this study provide the technical basis for the cell size selection in the GOTHIC distributed parameter models used for analysing hydrogen mixing behaviour. (author). 1 ref., 1 tab., 13 figs

  8. Size-controlled synthesis of SnO2 quantum dots and their gas-sensing performance

    International Nuclear Information System (INIS)

    Du, Jianping; Zhao, Ruihua; Xie, Yajuan; Li, Jinping

    2015-01-01

    Graphical abstract: The gas-sensing property of quantum dots is related to their sizes. SnO 2 quantum dots (TQDs) were synthesized and the sizes were controlled by a simple strategy. The results show that controlling QDs size is efficient to detect low-concentration hazardous volatile compounds selectively. - Highlights: • SnO 2 quantum dots with controllable size were synthesized by hydrothermal route. • The sizes of SnO 2 quantum dots (TQDs) were controlled by a simple strategy. • The responses to volatile chemicals strongly depend on the size of quantum dots. • Small-size TQDs exhibit a good selectivity and response to triethylamine. • Controlling size is efficient to detect low-concentration toxic gases selectively. - Abstract: Tin dioxide quantum dots (TQDs) with controllable size were synthesized by changing the amount of alkaline reagent in the hydrothermal process. The gas-sensing properties were investigated by operating chemoresistor type sensor. The morphology and structure were characterized by X-ray diffraction, scanning/transmission electron microscopy, UV–vis and Raman spectrometry. The as-synthesized SnO 2 shows the characteristics of quantum dots and the narrowest size distribution is about 2–3 nm. The gas-sensing results indicate that the responses are strongly dependent on the size of quantum dots. TQDs with different sizes exhibit different sensitivities and selectivities to volatile toxic chemicals such as aldehyde, acetone, methanol, ethanol and amine. Especially, when the sensors are exposed to 100 ppm triethylamine (TEA), the sensing response value of TQDs with small size is two times higher than that of the large-size TQDs. The maximum response values of TQDs to 1 ppm and 100 ppm TEA are 15 and 153, respectively. The response time is 1 s and the recovery time is 47 s upon exposure to 1 ppm TEA. The results suggest that it is an effective method by regulating the size of SnO 2 quantum dots to detect low-concentration hazardous

  9. Effect of silica nanoparticles with variable size and surface functionalization on human endothelial cell viability and angiogenic activity

    Science.gov (United States)

    Guarnieri, Daniela; Malvindi, Maria Ada; Belli, Valentina; Pompa, Pier Paolo; Netti, Paolo

    2014-02-01

    Silica nanoparticles could be promising delivery vehicles for drug targeting or gene therapy. However, few studies have been undertaken to determine the biological behavior effects of silica nanoparticles on primary endothelial cells. Here we investigated uptake, cytotoxicity and angiogenic properties of silica nanoparticle with positive and negative surface charge and sizes ranging from 25 to 115 nm in primary human umbilical vein endothelial cells. Dynamic light scattering measurements and nanoparticle tracking analysis were used to estimate the dispersion status of nanoparticles in cell culture media, which was a key aspect to understand the results of the in vitro cellular uptake experiments. Nanoparticles were taken up by primary endothelial cells in a size-dependent manner according to their degree of agglomeration occurring after transfer in cell culture media. Functionalization of the particle surface with positively charged groups enhanced the in vitro cellular uptake, compared to negatively charged nanoparticles. However, this effect was contrasted by the tendency of particles to form agglomerates, leading to lower internalization efficiency. Silica nanoparticle uptake did not affect cell viability and cell membrane integrity. More interestingly, positively and negatively charged 25 nm nanoparticles did not influence capillary-like tube formation and angiogenic sprouting, compared to controls. Considering the increasing interest in nanomaterials for several biomedical applications, a careful study of nanoparticle-endothelial cells interactions is of high relevance to assess possible risks associated to silica nanoparticle exposure and their possible applications in nanomedicine as safe and effective nanocarriers for vascular transport of therapeutic agents.

  10. Insulin/IGF-regulated size scaling of neuroendocrine cells expressing the bHLH transcription factor Dimmed in Drosophila.

    Directory of Open Access Journals (Sweden)

    Jiangnan Luo

    Full Text Available Neurons and other cells display a large variation in size in an organism. Thus, a fundamental question is how growth of individual cells and their organelles is regulated. Is size scaling of individual neurons regulated post-mitotically, independent of growth of the entire CNS? Although the role of insulin/IGF-signaling (IIS in growth of tissues and whole organisms is well established, it is not known whether it regulates the size of individual neurons. We therefore studied the role of IIS in the size scaling of neurons in the Drosophila CNS. By targeted genetic manipulations of insulin receptor (dInR expression in a variety of neuron types we demonstrate that the cell size is affected only in neuroendocrine cells specified by the bHLH transcription factor DIMMED (DIMM. Several populations of DIMM-positive neurons tested displayed enlarged cell bodies after overexpression of the dInR, as well as PI3 kinase and Akt1 (protein kinase B, whereas DIMM-negative neurons did not respond to dInR manipulations. Knockdown of these components produce the opposite phenotype. Increased growth can also be induced by targeted overexpression of nutrient-dependent TOR (target of rapamycin signaling components, such as Rheb (small GTPase, TOR and S6K (S6 kinase. After Dimm-knockdown in neuroendocrine cells manipulations of dInR expression have significantly less effects on cell size. We also show that dInR expression in neuroendocrine cells can be altered by up or down-regulation of Dimm. This novel dInR-regulated size scaling is seen during postembryonic development, continues in the aging adult and is diet dependent. The increase in cell size includes cell body, axon terminations, nucleus and Golgi apparatus. We suggest that the dInR-mediated scaling of neuroendocrine cells is part of a plasticity that adapts the secretory capacity to changing physiological conditions and nutrient-dependent organismal growth.

  11. A Total Quality-Control Plan with Right-Sized Statistical Quality-Control.

    Science.gov (United States)

    Westgard, James O

    2017-03-01

    A new Clinical Laboratory Improvement Amendments option for risk-based quality-control (QC) plans became effective in January, 2016. Called an Individualized QC Plan, this option requires the laboratory to perform a risk assessment, develop a QC plan, and implement a QC program to monitor ongoing performance of the QC plan. Difficulties in performing a risk assessment may limit validity of an Individualized QC Plan. A better alternative is to develop a Total QC Plan including a right-sized statistical QC procedure to detect medically important errors. Westgard Sigma Rules provides a simple way to select the right control rules and the right number of control measurements. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Engineering tolerance using biomaterials to target and control antigen presenting cells.

    Science.gov (United States)

    Tostanoski, Lisa H; Gosselin, Emily A; Jewell, Christopher M

    2016-05-01

    Autoimmune diseases occur when cells of the adaptive immune system incorrectly recognize and attack "self" tissues. Importantly, the proliferation and differentiation of these cells is triggered and controlled by interactions with antigen presenting cells (APCs), such as dendritic cells. Thus, modulating the signals transduced by APCs (e.g., cytokines, costimulatory surface proteins) has emerged as a promising strategy to promote tolerance for diseases such as multiple sclerosis, type 1 diabetes, and lupus. However, many approaches have been hindered by non-specific activity of immunosuppressive or immunoregulatory cues, following systemic administration of soluble factors via traditional injections routes (e.g., subcutaneous, intravenous). Biomaterials offer a unique opportunity to control the delivery of tolerogenic signals in vivo via properties such as controlled particle size, tunable release kinetics, and co-delivery of multiple classes of cargo. In this review, we highlight recent reports that exploit these properties of biomaterials to target APCs and promote tolerance via three strategies, i) passive or active targeting of particulate carriers to APCs, ii) biomaterial-mediated control over antigen localization and processing, and iii) targeted delivery of encapsulated or adsorbed immunomodulatory signals. These reports represent exciting advances toward the goal of more effective therapies for autoimmune diseases, without the broad suppressive effects associated with current clinically-approved therapies.

  13. Perturbation of nucleo-cytoplasmic transport affects size of nucleus and nucleolus in human cells.

    Science.gov (United States)

    Ganguly, Abira; Bhattacharjee, Chumki; Bhave, Madhura; Kailaje, Vaishali; Jain, Bhawik K; Sengupta, Isha; Rangarajan, Annapoorni; Bhattacharyya, Dibyendu

    2016-03-01

    Size regulation of human cell nucleus and nucleolus are poorly understood subjects. 3D reconstruction of live image shows that the karyoplasmic ratio (KR) increases by 30-80% in transformed cell lines compared to their immortalized counterpart. The attenuation of nucleo-cytoplasmic transport causes the KR value to increase by 30-50% in immortalized cell lines. Nucleolus volumes are significantly increased in transformed cell lines and the attenuation of nucleo-cytoplasmic transport causes a significant increase in the nucleolus volume of immortalized cell lines. A cytosol and nuclear fraction swapping experiment emphasizes the potential role of unknown cytosolic factors in nuclear and nucleolar size regulation. © 2016 Federation of European Biochemical Societies.

  14. When larger brains do not have more neurons: Increased numbers of cells are compensated by decreased average cell size across mouse individuals

    Directory of Open Access Journals (Sweden)

    Suzana eHerculano-Houzel

    2015-06-01

    Full Text Available There is a strong trend toward increased brain size in mammalian evolution, with larger brains composed of more and larger neurons than smaller brains across species within each mammalian order. Does the evolution of increased numbers of brain neurons, and thus larger brain size, occur simply through the selection of individuals with more and larger neurons, and thus larger brains, within a population? That is, do individuals with larger brains also have more, and larger, neurons than individuals with smaller brains, such that allometric relationships across species are simply an extension of intraspecific scaling? Here we show that this is not the case across adult male mice of a similar age. Rather, increased numbers of neurons across individuals are accompanied by increased numbers of other cells and smaller average cell size of both types, in a trade-off that explains how increased brain mass does not necessarily ensue. Fundamental regulatory mechanisms thus must exist that tie numbers of neurons to numbers of other cells and to average cell size within individual brains. Finally, our results indicate that changes in brain size in evolution are not an extension of individual variation in numbers of neurons, but rather occur through step changes that must simultaneously increase numbers of neurons and cause cell size to increase, rather than decrease.

  15. Size Control of Sessile Microbubbles for Reproducibly Driven Acoustic Streaming

    Science.gov (United States)

    Volk, Andreas; Kähler, Christian J.

    2018-05-01

    Acoustically actuated bubbles are receiving growing interest in microfluidic applications, as they induce a streaming field that can be used for particle sorting and fluid mixing. An essential but often unspoken challenge in such applications is to maintain a constant bubble size to achieve reproducible conditions. We present an automatized system for the size control of a cylindrical bubble that is formed at a blind side pit of a polydimethylsiloxane microchannel. Using a pressure control system, we adapt the protrusion depth of the bubble into the microchannel to a precision of approximately 0.5 μ m on a timescale of seconds. By comparing the streaming field generated by bubbles of width 80 μ m with a protrusion depth between -12 and 60 μ m , we find that the mean velocity of the induced streaming fields varies by more than a factor of 4. We also find a qualitative change of the topology of the streaming field. Both observations confirm the importance of the bubble size control system in order to achieve reproducible and reliable bubble-driven streaming experiments.

  16. Microfluidic size separation of cells and particles using a swinging bucket centrifuge.

    Science.gov (United States)

    Yeo, Joo Chuan; Wang, Zhiping; Lim, Chwee Teck

    2015-09-01

    Biomolecular separation is crucial for downstream analysis. Separation technique mainly relies on centrifugal sedimentation. However, minuscule sample volume separation and extraction is difficult with conventional centrifuge. Furthermore, conventional centrifuge requires density gradient centrifugation which is laborious and time-consuming. To overcome this challenge, we present a novel size-selective bioparticles separation microfluidic chip on a swinging bucket minifuge. Size separation is achieved using passive pressure driven centrifugal fluid flows coupled with centrifugal force acting on the particles within the microfluidic chip. By adopting centrifugal microfluidics on a swinging bucket rotor, we achieved over 95% efficiency in separating mixed 20 μm and 2 μm colloidal dispersions from its liquid medium. Furthermore, by manipulating the hydrodynamic resistance, we performed size separation of mixed microbeads, achieving size efficiency of up to 90%. To further validate our device utility, we loaded spiked whole blood with MCF-7 cells into our microfluidic device and subjected it to centrifugal force for a mere duration of 10 s, thereby achieving a separation efficiency of over 75%. Overall, our centrifugal microfluidic device enables extremely rapid and label-free enrichment of different sized cells and particles with high efficiency.

  17. Efficiency optimized control of medium-size induction motor drives

    DEFF Research Database (Denmark)

    Abrahamsen, F.; Blaabjerg, Frede; Pedersen, John Kim

    2000-01-01

    The efficiency of a variable speed induction motor drive can be optimized by adaption of the motor flux level to the load torque. In small drives (<10 kW) this can be done without considering the relatively small converter losses, but for medium-size drives (10-1000 kW) the losses can not be disr......The efficiency of a variable speed induction motor drive can be optimized by adaption of the motor flux level to the load torque. In small drives (... not be disregarded without further analysis. The importance of the converter losses on efficiency optimization in medium-size drives is analyzed in this paper. Based on the experiments with a 90 kW drive it is found that it is not critical if the converter losses are neglected in the control, except...... that the robustness towards load disturbances may unnecessarily be reduced. Both displacement power factor and model-based efficiency optimizing control methods perform well in medium-size drives. The last strategy is also tested on a 22 kW drive with good results....

  18. Size-controllable polypyrrole nanospheres synthesized in the presence of phosphorylated chitosan and their size effect in different applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Cao, Yi; Lu, Yun, E-mail: yunlu@nju.edu.cn [Nanjing University, Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, School of Chemistry and Chemical Engineering (China)

    2015-05-15

    The size-controllable polypyrrole (PPy) nanospheres are successfully synthesized by oxidative polymerization of pyrrole using N-methylene phosphonic chitosan (NMPC) as a structure-directing agent. By simply changing the amount of NMPC, the size of the PPy nanospheres can be adjusted from 190 to 50 nm in diameter. The spectrometric results suggest that the electrostatic interactions of phosphate groups in NMPC molecule with pyrrole ring might be a driving force for formation of the uniform and size-controllable PPy nanospheres. The PPy nanospheres with the diameter of 100 nm exhibit the largest capacity and a good cycling stability as electrode materials of supercapacitors. The as-prepared PPy nanospheres also can be combined with carbon dots to form composite nanospheres presenting enhanced fluorescence intensity, which show potential application in fluorescence detection.

  19. The Size of Activating and Inhibitory Killer Ig-like Receptor Nanoclusters Is Controlled by the Transmembrane Sequence and Affects Signaling

    Directory of Open Access Journals (Sweden)

    Anna Oszmiana

    2016-05-01

    Full Text Available Super-resolution microscopy has revealed that immune cell receptors are organized in nanoscale clusters at cell surfaces and immune synapses. However, mechanisms and functions for this nanoscale organization remain unclear. Here, we used super-resolution microscopy to compare the surface organization of paired killer Ig-like receptors (KIR, KIR2DL1 and KIR2DS1, on human primary natural killer cells and cell lines. Activating KIR2DS1 assembled in clusters two-fold larger than its inhibitory counterpart KIR2DL1. Site-directed mutagenesis established that the size of nanoclusters is controlled by transmembrane amino acid 233, a lysine in KIR2DS1. Super-resolution microscopy also revealed two ways in which the nanoscale clustering of KIR affects signaling. First, KIR2DS1 and DAP12 nanoclusters are juxtaposed in the resting cell state but coalesce upon receptor ligation. Second, quantitative super-resolution microscopy revealed that phosphorylation of the kinase ZAP-70 or phosphatase SHP-1 is favored in larger KIR nanoclusters. Thus, the size of KIR nanoclusters depends on the transmembrane sequence and affects downstream signaling.

  20. Replicon sizes in mammalian cells as estimated by an x-ray plus bromodeoxyuridine photolysis method

    International Nuclear Information System (INIS)

    Kapp, L.N.; Painter, R.B.

    1978-01-01

    A new method is described for estimating replicon sizes in mammalian cells. Cultures were pulse labeled with [ 3 H]thymidine ([ 3 H]TdR) and bromodeoxyuridine (BrDUrd) for up to 1 h. The lengths of the resulting labeled regions of DNA, L/sub obs/, were estimated by a technique wherein the change in molecular weight of nascent DNA strands, induced by 313 nm light, is measured by velocity sedimentation in alkaline sucrose gradients. If cells are exposed to 1,000 rads of x rays immediately before pulse labeling, initiation of replicon operation is blocked, although chain elongation proceeds almost normally. Under these conditions L/sub obs/ continues to increase only until operating replicons have completed their replication. This value for L/sub obs/ then remains constant as long as the block to initiation remains and represents an estimate for the average size of replicons operating in the cells before x irradiation. For human diploid fibroblasts and human HeLa cells this estimated average size is approximately 17 μM, whereas for Chinese hamster ovary cells, the average replicon size is about 42 μM

  1. Combined Optimal Sizing and Control for a Hybrid Tracked Vehicle

    Directory of Open Access Journals (Sweden)

    Huei Peng

    2012-11-01

    Full Text Available The optimal sizing and control of a hybrid tracked vehicle is presented and solved in this paper. A driving schedule obtained from field tests is used to represent typical tracked vehicle operations. Dynamics of the diesel engine-permanent magnetic AC synchronous generator set, the lithium-ion battery pack, and the power split between them are modeled and validated through experiments. Two coupled optimizations, one for the plant parameters, forming the outer optimization loop and one for the control strategy, forming the inner optimization loop, are used to achieve minimum fuel consumption under the selected driving schedule. The dynamic programming technique is applied to find the optimal controller in the inner loop while the component parameters are optimized iteratively in the outer loop. The results are analyzed, and the relationship between the key parameters is observed to keep the optimal sizing and control simultaneously.

  2. Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells

    Science.gov (United States)

    Kourkoutis, Lena F.; Hao, Xiaojing; Huang, Shujuan; Puthen-Veettil, Binesh; Conibeer, Gavin; Green, Martin A.; Perez-Wurfl, Ivan

    2013-07-01

    All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to

  3. Micro-environmental mechanical stress controls tumor spheroid size and morphology by suppressing proliferation and inducing apoptosis in cancer cells.

    Directory of Open Access Journals (Sweden)

    Gang Cheng

    Full Text Available Compressive mechanical stress produced during growth in a confining matrix limits the size of tumor spheroids, but little is known about the dynamics of stress accumulation, how the stress affects cancer cell phenotype, or the molecular pathways involved.We co-embedded single cancer cells with fluorescent micro-beads in agarose gels and, using confocal microscopy, recorded the 3D distribution of micro-beads surrounding growing spheroids. The change in micro-bead density was then converted to strain in the gel, from which we estimated the spatial distribution of compressive stress around the spheroids. We found a strong correlation between the peri-spheroid solid stress distribution and spheroid shape, a result of the suppression of cell proliferation and induction of apoptotic cell death in regions of high mechanical stress. By compressing spheroids consisting of cancer cells overexpressing anti-apoptotic genes, we demonstrate that mechanical stress-induced apoptosis occurs via the mitochondrial pathway.Our results provide detailed, quantitative insight into the role of micro-environmental mechanical stress in tumor spheroid growth dynamics, and suggest how tumors grow in confined locations where the level of solid stress becomes high. An important implication is that apoptosis via the mitochondrial pathway, induced by compressive stress, may be involved in tumor dormancy, in which tumor growth is held in check by a balance of apoptosis and proliferation.

  4. Size Controlled Synthesis of Starch Nanoparticles by a Microemulsion Method

    Directory of Open Access Journals (Sweden)

    Suk Fun Chin

    2014-01-01

    Full Text Available Controllable particles sizes of starch nanoparticles were synthesized via a precipitation in water-in-oil microemulsion approach. Microemulsion method offers the advantages of ultralow interfacial tension, large interfacial area, and being thermodynamically stable and affords monodispersed nanoparticles. The synthesis parameters such as stirring rates, ratios of oil/cosurfactant, oil phases, cosurfactants, and ratios of water/oil were found to affect the mean particle size of starch nanoparticles. Starch nanoparticles with mean particles sizes of 109 nm were synthesized by direct nanoprecipitation method, whereas by using precipitation in microemulsion approach, starch nanoparticles with smaller mean particles sizes of 83 nm were obtained.

  5. Biomimetic Nanoarchitectures for the Study of T Cell Activation with Single-Molecule Control

    Science.gov (United States)

    Cai, Haogang

    Physical factors in the environment of a cell affect its function and behavior in a variety of ways. There is increasing evidence that, among these factors, the geometric arrangement of receptor ligands plays an important role in setting the conditions for critical cellular processes. The goal of this thesis is to develop new techniques for probing the role of extracellular ligand geometry, with a focus on T cell activation. In this work, top-down molecular-scale nanofabrication and bottom-up selective self-assembly were combined in order to present functional nanomaterials (primarily biomolecules) on a surface with precise spatial control and single-molecule resolution. Such biomolecule nanoarrays are becoming an increasingly important tool in surface-based in vitro assays for biosensing, molecular and cellular studies. The nanoarrays consist of metallic nanodots patterned on glass coverslips using electron beam and nanoimprint lithography, combined with self-aligned pattern transfer. The nanodots were then used as anchors for the immobilization of biological ligands, and backfilled with a protein-repellent passivation layer of polyethylene glycol. The passivation efficiency was improved to minimize nonspecific adsorption. In order to ensure true single-molecule control, we developed an on-chip protocol to measure the molecular occupancy of nanodot arrays based on fluorescence photobleaching, while accounting for quenching effects by plasmonic absorption. We found that the molecular occupancy can be interpreted as a packing problem, with the solution depending on the nanodot size and the concentration of self-assembly reagents, where the latter can be easily adjusted to control the molecular occupancy according to the dot size. The optimized nanoarrays were used as biomimetic architectures for the study of T cell activation with single-molecule control. T cell activation involves an elaborate arrangement of signaling, adhesion, and costimulatory molecules

  6. Controlled synthesis of graphene sheets with tunable sizes by hydrothermal cutting

    International Nuclear Information System (INIS)

    Ma Chen; Chen Zhongxin; Fang Ming; Lu Hongbin

    2012-01-01

    We report a hydrothermal method that directly reduces graphene oxide (GO) into graphene nanosheets (GNs) with different sizes. In the presence of NaOH and hydrazine, the hydrothermal reaction at 80 °C resulted in the formation of GNs with a lateral size of ∼1 μm but the size of GNs decreased to ∼300 and ∼100 nm upon increasing the reaction temperature to 150 and 200 °C, respectively. The morphology of the resulting GNs was observed by atomic force microscopy and transmission electron microscopy. The thickness of GNs is basically <3 nm, indicates the GNs stack together in a few-layer manner. XRD, XPS, FTIR, and Raman spectroscopy were used to characterize the structural changes before and after reduction. The results suggested that the defect stability in GO and reduced GNs could be responsible for the temperature dependence of the size of reduced GNs.Graphical AbstractA hydrothermal method is proposed to simultaneously reduce and cut graphene oxide into graphene sheets with different sizes in a controlled manner, in which the reaction temperature as a critical parameter is used to control the size of resulting graphene sheets.

  7. Size and dielectric properties of skeletal stem cells change critically after enrichment and expansion from human bone marrow: consequences for microfluidic cell sorting.

    Science.gov (United States)

    Xavier, Miguel; de Andrés, María C; Spencer, Daniel; Oreffo, Richard O C; Morgan, Hywel

    2017-08-01

    The capacity of bone and cartilage to regenerate can be attributed to skeletal stem cells (SSCs) that reside within the bone marrow (BM). Given SSCs are rare and lack specific surface markers, antibody-based sorting has failed to deliver the cell purity required for clinical translation. Microfluidics offers new methods of isolating cells based on biophysical features including, but not limited to, size, electrical properties and stiffness. Here we report the characterization of the dielectric properties of unexpanded SSCs using single-cell microfluidic impedance cytometry (MIC). Unexpanded SSCs had a mean size of 9.0 µm; larger than the majority of BM cells. During expansion, often used to purify and increase the number of SSCs, cell size and membrane capacitance increased significantly, highlighting the importance of characterizing unaltered SSCs. In addition, MIC was used to track the osteogenic differentiation of SSCs and showed an increased membrane capacitance with differentiation. The electrical properties of primary SSCs were indistinct from other BM cells precluding its use as an isolation method. However, the current studies indicate that cell size in combination with another biophysical parameter, such as stiffness, could be used to design label-free devices for sorting SSCs with significant clinical impact. © 2017 The Authors.

  8. The crypt and cell size kinetics in the irradiated intestinal epithelium in mice

    International Nuclear Information System (INIS)

    Kononenko, A.M.; Gagarin, A.U.

    1975-01-01

    A study has been made of changes in the average values of the axial cross-sectional area of the crypt and of cell area in this cross-section for eight days after a single whole-body exposure of male mice to 400 rad of X-rays. A small reduction in the crypt area in the destructive period gives way to a much greater increase in the normal dimensions of the area in the regenerative period. Two very considerable waves of anomalous increase are observed in the dimensions of the cryptal cell cross-sections, the first in the destructive and the second in the regenerative period. These fluctuations in cell dimensions do not occur around but above the control level, attaining the latter level only at the minimum (4th day). The size of the cryptal cells of the intact intestinal epithelium is evidently close to the minimum needed for enterocyte proliferation. The considerable increase in crypt dimensions in the regenerative period (beginning from the 6th day) is not due to the larger number of cells (they are even somewhat fewer than normal) but rather to a substantial increase in cell dimensions. Thus, according to these data, on the 6th-8th day after irradiation the intestinal epithelium deviates strongly from the stationary state. The index I sub(v), where I is the mitotic index and v the cell volume, was used to evaluate the changes in the value of the material stream, connected with proliferation, to the intestinal epithelium per cryptal cell. A considerable increase was found in this stream (hypertrophy of proliferative cells) in the intestinal epithelium restored after irradiation. (author)

  9. Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

    Science.gov (United States)

    Moens, Tom; Vafeiadou, Anna-Maria; De Geyter, Ellen; Vanormelingen, Pieter; Sabbe, Koen; De Troch, Marleen

    2014-09-01

    We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had δ13C indicating that MPB is their major carbon source. δ15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

  10. Modeling, analysis and control of fuel cell hybrid power systems

    Science.gov (United States)

    Suh, Kyung Won

    due to the conflicting objectives. The compromise can be mitigated by augmenting the fuel cell power system with an energy buffer such as a battery. We consider two different and popular ways of connecting the battery and the fuel cell to the load and we refer to them as electric architectures. Various controller gains are used to span the fuel cell operation from load-following to load-leveling, and hence, to determine adequate fuel cell-battery sizing (hybridization level) and the associated trends in the system efficiency.

  11. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hanguang [Department; Hwang, Sooyeon [Center; Wang, Maoyu [School; Feng, Zhenxing [School; Karakalos, Stavros [Department; Luo, Langli [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Qiao, Zhi [Department; Xie, Xiaohong [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wang, Chongmin [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Su, Dong [Center; Shao, Yuyan [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wu, Gang [Department

    2017-09-26

    To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that is determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.

  12. Improved Light Conversion Efficiency Of Dye-Sensitized Solar Cell By Dispersing Submicron-Sized Granules Into The Nano-Sized TiO2 Layer

    Directory of Open Access Journals (Sweden)

    Song S.A.

    2015-06-01

    Full Text Available In this work, TiO2 nanoparticles and submicron-sized granules were synthesized by a hydrothermal method and spray pyrolysis, respectively. Submicron-sized granules were dispersed into the nano-sized TiO2 layer to improve the light conversion efficiency. Granules showed better light scattering, but lower in terms of the dye-loading quantity and recombination resistance compared with nanoparticles. Consequently, the nano-sized TiO2 layer had higher cell efficiency than the granulized TiO2 layer. When dispersed granules into the nanoparticle layer, the light scattering was enhanced without the loss of dye-loading quantities. The dispersion of granulized TiO2 led to increase the cell efficiency up to 6.51%, which was about 5.2 % higher than that of the electrode consisting of only TiO2 nanoparticles. Finally, the optimal hydrothermal temperature and dispersing quantity of granules were found to be 200°C and 20 wt%, respectively.

  13. Isotropic 2D quadrangle meshing with size and orientation control

    KAUST Repository

    Pellenard, Bertrand

    2011-12-01

    We propose an approach for automatically generating isotropic 2D quadrangle meshes from arbitrary domains with a fine control over sizing and orientation of the elements. At the heart of our algorithm is an optimization procedure that, from a coarse initial tiling of the 2D domain, enforces each of the desirable mesh quality criteria (size, shape, orientation, degree, regularity) one at a time, in an order designed not to undo previous enhancements. Our experiments demonstrate how well our resulting quadrangle meshes conform to a wide range of input sizing and orientation fields.

  14. The thermal environment of the nest affects body and cell size in the solitary red mason bee (Osmia bicornis L.).

    Science.gov (United States)

    Kierat, Justyna; Szentgyörgyi, Hajnalka; Czarnoleski, Marcin; Woyciechowski, Michał

    2017-08-01

    Many ectotherms grow larger at lower temperatures than at higher temperatures. This pattern, known as the temperature-size rule, is often accompanied by plastic changes in cell size, which can mechanistically explain the thermal dependence of body size. However, the theory predicts that thermal plasticity in cell size has adaptive value for ectotherms because there are different optimal cell-membrane-to-cell-volume ratios at different temperatures. At high temperatures, the demand for oxygen is high; therefore, a large membrane surface of small cells is beneficial because it allows high rates of oxygen transport into the cell. The metabolic costs of maintaining membranes become more important at low temperatures than at high temperatures, which favours large cells. In a field experiment, we manipulated the thermal conditions inside nests of the red mason bee, a solitary bee that does not regulate the temperature in its nests and whose larvae develop under ambient conditions. We assessed the effect of temperature on body mass and ommatidia size (our proxy of cell size). The body and cell sizes decreased in response to a higher mean temperature and greater temperature fluctuations. This finding is in accordance with predictions of the temperature-size rule and optimal cell size theory and suggests that both the mean temperature and the magnitude of temperature fluctuations are important for determining body and cell sizes. Additionally, we observed that males of the red mason bee tend to have larger ommatidia in relation to their body mass than females, which might play an important role during mating flight. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Leukemia in AKR mice. III. Size distribution of suppressor T-cells in AKR leukemia and neonatal mice

    International Nuclear Information System (INIS)

    Mulder, A.M.; Durdik, J.M.; Toth, P.; Golub, E.S.

    1978-01-01

    Suppression of in vitro antibody forming potential of normal cells by leukemic cells of AKR and normal neonatal mice have many similarities. In both cases the suppression is by cell contact rather than by the elaboration of soluble suppressive factors and the suppression is sensitive to both x-irradiation and mitomycin C treatment. When the size distribution of suppressing cells in thymus and spleen were compared by velocity sedimentation, both leukemic and neonatal suppressing cells had similar size distribution in each organ. Both large and small cells in the thymus suppress but only large cells (sedimentation velocity > 3.5 mm/hr) in the spleen are able to suppress. Leukemic cells in lymph node have a splenic size distribution, viz., only large cells suppress. Both large and small cells of a subcutaneously growing long passage AKR lymphoma are able to suppress. While large cells contain the bulk of cells actively incorporating tritiated thymidine and thus probably in cycle, small but significant amounts of incorporation in small suppressing cells is also seen

  16. A qualitative study of psychological, social and behavioral barriers to appropriate food portion size control.

    Science.gov (United States)

    Spence, Michelle; Livingstone, M Barbara E; Hollywood, Lynsey E; Gibney, Eileen R; O'Brien, Sinéad A; Pourshahidi, L Kirsty; Dean, Moira

    2013-08-01

    Given the worldwide prevalence of overweight and obesity, there is a clear need for meaningful practical healthy eating advice - not only in relation to food choice, but also on appropriate food portion sizes. As the majority of portion size research to date has been overwhelmingly quantitative in design, there is a clear need to qualitatively explore consumers' views in order to fully understand how food portion size decisions are made. Using qualitative methodology this present study aimed to explore consumers' views about factors influencing their portion size selection and consumption and to identify barriers to appropriate portion size control. Ten focus groups with four to nine participants in each were formed with a total of 66 persons (aged 19-64 years) living on the island of Ireland. The semi-structured discussions elicited participants' perceptions of suggested serving size guidance and explored the influence of personal, social and environmental factors on their food portion size consumption. Audiotapes of the discussions were professionally transcribed verbatim, loaded into NVivo 9, and analysed using an inductive thematic analysis procedure. The rich descriptive data derived from participants highlight that unhealthy portion size behaviors emanate from various psychological, social and behavioral factors. These bypass reflective and deliberative control, and converge to constitute significant barriers to healthy portion size control. Seven significant barriers to healthy portion size control were apparent: (1) lack of clarity and irrelevance of suggested serving size guidance; (2) guiltless eating; (3) lack of self-control over food cues; (4) distracted eating; (5) social pressures; (6) emotional eating rewards; and (7) quantification habits ingrained from childhood. Portion size control strategies should empower consumers to overcome these effects so that the consumption of appropriate food portion sizes becomes automatic and habitual.

  17. Revisionist integral deferred correction with adaptive step-size control

    KAUST Repository

    Christlieb, Andrew; Macdonald, Colin; Ong, Benjamin; Spiteri, Raymond

    2015-01-01

    © 2015 Mathematical Sciences Publishers. Adaptive step-size control is a critical feature for the robust and efficient numerical solution of initial-value problems in ordinary differential equations. In this paper, we show that adaptive step

  18. Endocytic pathways involved in PLGA nanoparticle uptake by grapevine cells and role of cell wall and membrane in size selection.

    Science.gov (United States)

    Palocci, Cleofe; Valletta, Alessio; Chronopoulou, Laura; Donati, Livia; Bramosanti, Marco; Brasili, Elisa; Baldan, Barbara; Pasqua, Gabriella

    2017-12-01

    PLGA NPs' cell uptake involves different endocytic pathways. Clathrin-independent endocytosis is the main internalization route. The cell wall plays a more prominent role than the plasma membrane in NPs' size selection. In the last years, many studies on absorption and cell uptake of nanoparticles by plants have been conducted, but the understanding of the internalization mechanisms is still largely unknown. In this study, polydispersed and monodispersed poly(lactic-co-glycolic) acid nanoparticles (PLGA NPs) were synthesized, and a strategy combining the use of transmission electron microscopy (TEM), confocal analysis, fluorescently labeled PLGA NPs, a probe for endocytic vesicles (FM4-64), and endocytosis inhibitors (i.e., wortmannin, ikarugamycin, and salicylic acid) was employed to shed light on PLGA NP cell uptake in grapevine cultured cells and to assess the role of the cell wall and plasma membrane in size selection of PLGA NPs. The ability of PLGA NPs to cross the cell wall and membrane was confirmed by TEM and fluorescence microscopy. A strong adhesion of PLGA NPs to the outer side of the cell wall was observed, presumably due to electrostatic interactions. Confocal microscopy and treatment with endocytosis inhibitors suggested the involvement of both clathrin-dependent and clathrin-independent endocytosis in cell uptake of PLGA NPs and the latter appeared to be the main internalization pathway. Experiments on grapevine protoplasts revealed that the cell wall plays a more prominent role than the plasma membrane in size selection of PLGA NPs. While the cell wall prevents the uptake of PLGA NPs with diameters over 50 nm, the plasma membrane can be crossed by PLGA NPs with a diameter of 500-600 nm.

  19. Lin28a regulates germ cell pool size and fertility

    Science.gov (United States)

    Shinoda, Gen; de Soysa, T. Yvanka; Seligson, Marc T.; Yabuuchi, Akiko; Fujiwara, Yuko; Huang, Pei Yi; Hagan, John P.; Gregory, Richard I.; Moss, Eric G.; Daley, George Q.

    2013-01-01

    Overexpression of LIN28A is associated with human germ cell tumors and promotes primordial germ cell (PGC) development from embryonic stem cells in vitro and in chimeric mice. Knockdown of Lin28a inhibits PGC development in vitro, but how constitutional Lin28a deficiency affects the mammalian reproductive system in vivo remains unknown. Here, we generated Lin28a knockout (KO) mice and found that Lin28a deficiency compromises the size of the germ cell pool in both males and females by affecting PGC proliferation during embryogenesis. Interestingly however, in Lin28a KO males the germ cell pool partially recovers during postnatal expansion, while fertility remains impaired in both males and females mated to wild type mice. Embryonic overexpression of let-7, a microRNA negatively regulated by Lin28a, reduces the germ cell pool, corroborating the role of the Lin28a/let-7 axis in regulating the germ lineage. PMID:23378032

  20. Size-controlled synthesis of SnO{sub 2} quantum dots and their gas-sensing performance

    Energy Technology Data Exchange (ETDEWEB)

    Du, Jianping, E-mail: dujp518@163.com [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Zhao, Ruihua [Shanxi Kunming Tobacco Limited Liability Company, Taiyuan 030012, Shanxi (China); Xie, Yajuan [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Li, Jinping, E-mail: jpli211@hotmail.com [Research Institute of Special Chemicals, Taiyuan University of Technology, Shanxi, 030024 (China)

    2015-08-15

    Graphical abstract: The gas-sensing property of quantum dots is related to their sizes. SnO{sub 2} quantum dots (TQDs) were synthesized and the sizes were controlled by a simple strategy. The results show that controlling QDs size is efficient to detect low-concentration hazardous volatile compounds selectively. - Highlights: • SnO{sub 2} quantum dots with controllable size were synthesized by hydrothermal route. • The sizes of SnO{sub 2} quantum dots (TQDs) were controlled by a simple strategy. • The responses to volatile chemicals strongly depend on the size of quantum dots. • Small-size TQDs exhibit a good selectivity and response to triethylamine. • Controlling size is efficient to detect low-concentration toxic gases selectively. - Abstract: Tin dioxide quantum dots (TQDs) with controllable size were synthesized by changing the amount of alkaline reagent in the hydrothermal process. The gas-sensing properties were investigated by operating chemoresistor type sensor. The morphology and structure were characterized by X-ray diffraction, scanning/transmission electron microscopy, UV–vis and Raman spectrometry. The as-synthesized SnO{sub 2} shows the characteristics of quantum dots and the narrowest size distribution is about 2–3 nm. The gas-sensing results indicate that the responses are strongly dependent on the size of quantum dots. TQDs with different sizes exhibit different sensitivities and selectivities to volatile toxic chemicals such as aldehyde, acetone, methanol, ethanol and amine. Especially, when the sensors are exposed to 100 ppm triethylamine (TEA), the sensing response value of TQDs with small size is two times higher than that of the large-size TQDs. The maximum response values of TQDs to 1 ppm and 100 ppm TEA are 15 and 153, respectively. The response time is 1 s and the recovery time is 47 s upon exposure to 1 ppm TEA. The results suggest that it is an effective method by regulating the size of SnO{sub 2} quantum dots to detect low

  1. Sample size reassessment for a two-stage design controlling the false discovery rate.

    Science.gov (United States)

    Zehetmayer, Sonja; Graf, Alexandra C; Posch, Martin

    2015-11-01

    Sample size calculations for gene expression microarray and NGS-RNA-Seq experiments are challenging because the overall power depends on unknown quantities as the proportion of true null hypotheses and the distribution of the effect sizes under the alternative. We propose a two-stage design with an adaptive interim analysis where these quantities are estimated from the interim data. The second stage sample size is chosen based on these estimates to achieve a specific overall power. The proposed procedure controls the power in all considered scenarios except for very low first stage sample sizes. The false discovery rate (FDR) is controlled despite of the data dependent choice of sample size. The two-stage design can be a useful tool to determine the sample size of high-dimensional studies if in the planning phase there is high uncertainty regarding the expected effect sizes and variability.

  2. Iso-acoustic focusing of cells for size-insensitive acousto-mechanical phenotyping.

    Science.gov (United States)

    Augustsson, Per; Karlsen, Jonas T; Su, Hao-Wei; Bruus, Henrik; Voldman, Joel

    2016-05-16

    Mechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells' interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance of single cells in continuous flow. While flowing through a microchannel, cells migrate sideways, influenced by an acoustic field, into streams of increasing acoustic impedance, until reaching their cell-type specific point of zero acoustic contrast. We establish an experimental procedure and provide theoretical justifications and models for iso-acoustic focusing. We describe a method for providing a suitable acoustic contrast gradient in a cell-friendly medium, and use acoustic forces to maintain that gradient in the presence of destabilizing forces. Applying this method we demonstrate iso-acoustic focusing of cell lines and leukocytes, showing that acoustic properties provide phenotypic information independent of size.

  3. Energy harvesting from organic liquids in micro-sized microbial fuel cells

    KAUST Repository

    Mink, J.E.; Qaisi, R.M.; Logan, B.E.; Hussain, Muhammad Mustafa

    2014-01-01

    Micro-sized microbial fuel cells (MFCs) are miniature energy harvesters that use bacteria to convert biomass from liquids into usable power. The key challenge is transitioning laboratory test beds into devices capable of producing high power using

  4. Gas-phase laser synthesis of aggregation-free, size-controlled hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Bapat, Parimal V.; Kraft, Rebecca; Camata, Renato P.

    2012-01-01

    Nanophase hydroxyapatite (HA) is finding applications in many areas of biomedical research, including bone tissue engineering, drug delivery, and intracellular imaging. Details in chemical composition, crystal phase makeup, size, and shape of HA nanoparticles play important roles in achieving the favorable biological responses required in these applications. Most of the nanophase HA synthesis techniques involve solution-based methods that exhibit substantial aggregation of particles upon precipitation. Typically these methods also have limited control over the particle size and crystal phase composition. In this study, we describe the gas-phase synthesis of aggregation-free, size-controlled HA nanoparticles with mean size in the 20–70 nm range using laser ablation followed by aerosol electrical mobility classification. Nanoparticle deposits with adjustable number concentration were obtained on solid substrates. Particles were characterized by transmission electron microscopy, atomic force microscopy, and X-ray diffraction. Samples are well represented by log-normal size distributions with geometric standard deviation σ g ≈ 1.2. The most suitable conditions for HA nanoparticle formation at a laser fluence of 5 J/cm 2 were found to be a temperature of 800 °C and a partial pressure of water of 160 mbar.

  5. Influence of shear stress and size on viability of endothelial cells exposed to gold nanoparticles

    Science.gov (United States)

    Fede, C.; Albertin, Giovanna; Petrelli, L.; De Caro, R.; Fortunati, I.; Weber, V.; Ferrante, Camilla

    2017-09-01

    Screening nanoparticle toxicity directly on cell culture can be a fast and cheap technique. Nevertheless, to obtain results in accordance with those observed in live animals, the conditions in which cells are cultivated should resemble the one encountered in live systems. Microfluidic devices offer the possibility to satisfy this requirement, in particular with endothelial cell lines, because they are capable to reproduce the flowing media and shear stress experienced by these cell lines in vivo. In this work, we exploit a microfluidic device to observe how human umbilical vein endothelial cells (HUVEC) viability changes when subject to a continuous flow of culture medium, in which spherical citrate-stabilized gold nanoparticles of different sizes and at varying doses are investigated. For comparison, the same experiments are also run in multiwells where the cells do not experience the shear stress induced by the flowing medium. We discuss the results considering the influence of mode of exposure and nanoparticle size (24 and 13 nm). We observed that gold nanoparticles show a lower toxicity under flow conditions with respect to static and the HUVEC viability decreases as the nanoparticle surface area per unit volume increases, regardless of size.

  6. Retrieval of phytoplankton cell size from chlorophyll a specific absorption and scattering spectra of phytoplankton.

    Science.gov (United States)

    Zhou, Wen; Wang, Guifen; Li, Cai; Xu, Zhantang; Cao, Wenxi; Shen, Fang

    2017-10-20

    Phytoplankton cell size is an important property that affects diverse ecological and biogeochemical processes, and analysis of the absorption and scattering spectra of phytoplankton can provide important information about phytoplankton size. In this study, an inversion method for extracting quantitative phytoplankton cell size data from these spectra was developed. This inversion method requires two inputs: chlorophyll a specific absorption and scattering spectra of phytoplankton. The average equivalent-volume spherical diameter (ESD v ) was calculated as the single size approximation for the log-normal particle size distribution (PSD) of the algal suspension. The performance of this method for retrieving cell size was assessed using the datasets from cultures of 12 phytoplankton species. The estimations of a(λ) and b(λ) for the phytoplankton population using ESD v had mean error values of 5.8%-6.9% and 7.0%-10.6%, respectively, compared to the a(λ) and b(λ) for the phytoplankton populations using the log-normal PSD. The estimated values of C i ESD v were in good agreement with the measurements, with r 2 =0.88 and relative root mean square error (NRMSE)=25.3%, and relatively good performances were also found for the retrieval of ESD v with r 2 =0.78 and NRMSE=23.9%.

  7. Disc size regulation in the brood cell building behavior of leaf-cutter bee, Megachile tsurugensis.

    Science.gov (United States)

    Kim, Jong-yoon

    2007-12-01

    The leaf-cutter bee, Megachile tsurugensis, builds a brood cell in a preexisting tunnel with leaf discs that she cuts in decreasing sizes and assembles them like a Russian matryoshka doll. By experimentally manipulating the brood cell, it was investigated how she regulates the size of leaf discs that fit in the brood cell's internal volume. When the internal volume was artificially increased by removing a bulk of leaf discs, she decreased the leaf disc size, although increasing it would have made the leaf disc more fitting in the increased internal volume. As a reverse manipulation, when the internal volume was decreased by inserting a group of inner layers of preassembled leaf discs to a brood cell, she decreased the leaf disc size, so that the leaf disc could fit in the decreased internal volume. These results suggest that she uses at least two different mechanisms to regulate the disc size: the use of some internal memory about the degree of building work accomplished in the first and of sensory feedback of dimensional information at the construction site in the second manipulation, respectively. It was concluded that a stigmergic mechanism, an immediate sensory feedback from the brood cell changed by the building work, alone cannot explain the details of the bee's behavior particularly with respect to her initial response to the first manipulation. For a more complete explanation of the behavior exhibited by the solitary bee, two additional behavioral elements, reinforcement of building activity and processing of dimensional information, were discussed along with stigmergy.

  8. Small- and Medium-Sized Commercial Building Monitoring and Controls Needs: A Scoping Study

    Energy Technology Data Exchange (ETDEWEB)

    Katipamula, Srinivas; Underhill, Ronald M.; Goddard, James K.; Taasevigen, Danny J.; Piette, M. A.; Granderson, J.; Brown, Rich E.; Lanzisera, Steven M.; Kuruganti, T.

    2012-10-31

    Buildings consume over 40% of the total energy consumption in the U.S. A significant portion of the energy consumed in buildings is wasted because of the lack of controls or the inability to use existing building automation systems (BASs) properly. Much of the waste occurs because of our inability to manage and controls buildings efficiently. Over 90% of the buildings are either small-size (<5,000 sf) or medium-size (between 5,000 sf and 50,000 sf); these buildings currently do not use BASs to monitor and control their building systems from a central location. According to Commercial Building Energy Consumption Survey (CBECS), about 10% of the buildings in the U.S. use BASs or central controls to manage their building system operations. Buildings that use BASs are typically large (>100,000 sf). Lawrence Berkeley National Laboratory (LBNL), Oak Ridge National Laboratory (ORNL) and Pacific Northwest National Laboratory (PNNL) were asked by the U.S. Department of Energy’s (DOE’s) Building Technologies Program (BTP) to identify monitoring and control needs for small- and medium-sized commercial buildings and recommend possible solutions. This study documents the needs and solutions for small- and medium-sized buildings.

  9. Life cycle size dynamics in Didymosphenia geminata (Bacillariophyceae).

    Science.gov (United States)

    Bishop, Ian W; Spaulding, Sarah A

    2017-06-01

    Didymosphenia geminata has received a great deal of attention in the last 25 years, and considerable effort has gone into determining the origin, ecological impact, and economic consequences of its invasive behavior. While environmental conditions are a controlling influence in distribution, the extreme success of the species may be tied to its basic biology and life history. Little is known, however, about population dynamics, size restoration and reproduction of D. geminata. The objective of this study was to determine the temporal patterns in cell size frequency, size restoration strategy, and synchronization of life cycles between populations in close proximity. We implemented FlowCam technology to measure the length of more than 100,000 D. geminata cells from two sites in South Boulder Creek, Colorado over 1 year. We applied finite mixture modeling to uncover temporal patterns in size distribution. Our results show that collections of D. geminata exhibited a complex, multimodal size distribution, almost always containing four overlapping age cohorts. We failed to observe direct visual evidence of the sexual phase. Multiple abrupt and directional shifts in size distribution, however, were documented providing conclusive evidence of cell size restoration. Lastly, nodules in close proximity were asynchronous with respect to size frequency profiles and size diminution, highlighting the relevance of spatial heterogeneity in in situ diatom size dynamics. This study is the first to document the complexity of diatom cell size distribution in a lotic system, size restoration in D. geminata, and the variability in rates of size reduction at microhabitat spatial scales. © 2017 Phycological Society of America.

  10. Optimal sizing and control strategy of isolated grid with wind power and energy storage system

    International Nuclear Information System (INIS)

    Luo, Yi; Shi, Lin; Tu, Guangyu

    2014-01-01

    Highlights: • An energy storage sizing scheme for wind powered isolated grid is developed. • A bi-level control strategy for wind-battery isolated grid is proposed. • The energy storage type selection method for Nan’ao island grid is presented. • The sizing method and the control strategy are verified based on the Nan’ao island. • The wind-battery demonstration system has great benefit for remote areas. - Abstract: Integrating renewable energy and energy storage system provides a prospective way for power supply of remote areas. Focused on the isolated grids comprising renewable energy generation and energy storage, an energy storage sizing method for taking account of the reliability requirement and a bi-level control strategy of the isolated grids are presented in this paper. Based on comparative analysis of current energy storage characteristics and practicability, Sodium–sulfur battery is recommended for power balance control in the isolated grids. The optimal size of the energy storage system is determined by genetic algorithm and sequential simulation. The annualized cost considering the compensation cost of curtailed wind power and load is minimized when the reliability requirement can be satisfied. The sizing method emphasizes the tradeoff between energy storage size and reliability of power supply. The bi-level control strategy is designed as upper level wide area power balance control in dispatch timescale and lower level battery energy storage system V/f control in real-time range for isolated operation. The mixed timescale simulation results of Nan’ao Island grid verify the effectiveness of the proposed sizing method and control strategy

  11. Hyperplasia of smooth muscle in mild to moderate asthma without changes in cell size or gene expression.

    Science.gov (United States)

    Woodruff, Prescott G; Dolganov, Gregory M; Ferrando, Ronald E; Donnelly, Samantha; Hays, Steven R; Solberg, Owen D; Carter, Roderick; Wong, Hofer H; Cadbury, Peggy S; Fahy, John V

    2004-05-01

    Bronchial hyperresponsiveness in mild to moderate asthma may result from airway smooth muscle cell proliferation or acquisition of a hypercontractile phenotype. Because these cells have not been well characterized in mild to moderate asthma, we examined the morphometric and gene expression characteristics of smooth muscle cells in this subgroup of patients with asthma. Using bronchial biopsies from 14 subjects with mild to moderate asthma and 15 control subjects, we quantified smooth muscle cell morphology by stereology and the expression of a panel of genes related to a hypercontractile phenotype of airway smooth muscle, using laser microdissection and two-step real-time polymerase chain reaction. We found that airway smooth muscle cell size was similar in both groups, but cell number was nearly twofold higher in subjects with asthma (p = 0.03), and the amount of smooth muscle in the submucosa was increased 50-83% (p 0.1). We conclude that airway smooth muscle proliferation is a pathologic characteristic of subjects with mild to moderate asthma. However, smooth muscle cells in mild to moderate asthma do not show hypertrophy or gene expression changes of a hypercontractile phenotype observed in vitro.

  12. [Effects of moxibustion with seed-sized moxa cone on apoptosis of myocardial cells after sport fatigue in mice].

    Science.gov (United States)

    Xu, Huiqian; Hu, Yin; Gu, Yihuang; Zhang, Hongru

    2015-03-01

    To observe the effects of moxibustion on factors related with apoptosis of myocardial cells after sports fatigue in mice as well as the relationship among histone acetyltransferases p300 (p300), CREB binding protein (CBP) and cell apoptosis to discuss the role of p300 and CBP in moxibustion against apoptosis of myocardial cells. Sixty clean-grade male Kunming mice were randomly divided into a control group, a sport group and a moxibustion group, 20 cases in each one. Mice in all group received identical feeding environment. Mice in the control group did not received sport nor moxibustion; mice in the sport group and moxibustion group received non-weight swimming training which lasted from 30 min per day to 90 min per day gradually for 21 days; 1 h after swimming training, mice in the moxibustion group received moxibustion with seed-sized moxa cone at "Zusanli" (ST 36) and "Guanyuan" (CV 4), 5 cones at each acupoint, once a day for 21 days. 24 h after the final swimming training, cardiac muscle tissue was collected to test factor associated suicide (Fas), B cell lymphoma/lewkmia-2 (Bcl-2) by immunohistochemical method and expression of p300 and CBP. Compared with the control group, the apoptosis rate of myocardial cells in the sport group was significantly increased (Pprotein was significantly increased (Psport group, the apoptosis rate of myocardial cells in the moxibustion group was significantly reduced (Pprotein was significantly reduced (Psports fatigue in mice to inhibit the starting of apoptotic process, therefore reducing the apoptosis of myocardial cells after heavy exercise and protecting heart function.

  13. Cell wall microstructure, pore size distribution and absolute density of hemp shiv

    Science.gov (United States)

    Jiang, Y.; Lawrence, M.; Ansell, M. P.; Hussain, A.

    2018-04-01

    This paper, for the first time, fully characterizes the intrinsic physical parameters of hemp shiv including cell wall microstructure, pore size distribution and absolute density. Scanning electron microscopy revealed microstructural features similar to hardwoods. Confocal microscopy revealed three major layers in the cell wall: middle lamella, primary cell wall and secondary cell wall. Computed tomography improved the visualization of pore shape and pore connectivity in three dimensions. Mercury intrusion porosimetry (MIP) showed that the average accessible porosity was 76.67 ± 2.03% and pore size classes could be distinguished into micropores (3-10 nm) and macropores (0.1-1 µm and 20-80 µm). The absolute density was evaluated by helium pycnometry, MIP and Archimedes' methods. The results show that these methods can lead to misinterpretation of absolute density. The MIP method showed a realistic absolute density (1.45 g cm-3) consistent with the density of the known constituents, including lignin, cellulose and hemi-cellulose. However, helium pycnometry and Archimedes' methods gave falsely low values owing to 10% of the volume being inaccessible pores, which require sample pretreatment in order to be filled by liquid or gas. This indicates that the determination of the cell wall density is strongly dependent on sample geometry and preparation.

  14. Renal Epithelial Cell Injury Induced by Calcium Oxalate Monohydrate Depends on their Structural Features: Size, Surface, and Crystalline Structure.

    Science.gov (United States)

    Sun, Xin-Yuan; Ouyang, Jian-Ming; Gan, Qiong-Zhi; Liu, Ai-Jie

    2016-11-01

    Urinary crystals in normal and kidney stone patients often differ in crystal sizes and surface structures, but the effects of different crystal properties on renal tubular epithelial cells remain unclear. This study aimed to compare the cytotoxicity of micron/nano-calcium oxalate monohydrate (COM) crystals with sizes of 50 nm, 200 nm, 1 μm, 3 μm, and 10 μm to African green monkey renal epithelial (Vero) cells, to reveal the effect of crystal size and surface structure on cell injury, and to investigate the pathological mechanism of calcium oxalate kidney stones. Cell viability, cellular biochemical parameters, and internalized crystal amount in Vero cells were closely associated with the size of COM crystals. At the same concentration (200 μg/mL), COM-1 μm induced the most serious injury to Vero cells and caused the most significant change to cellular biochemical parameters, which were related to the specific porous structure and highest internalized amount in Vero cells. By contrast, COM-50 nm and COM-200 nm crystals lost their small size effect because of serious aggregation and weakened their toxicity to cells. COM-3 μm and COM-10 μm crystals were too large for cells to completely internalize; these crystals also exhibited a low specific surface area and thus weakened their toxicity. The excessive expression of intracellular ROS and reduction of the free-radical scavenger SOD were the main reasons for cell injury and eventually caused necrotic cell death. Crystal size, surface structure, aggregation, and internalization amount were closely related to the cytotoxicity of COM crystals.

  15. Impact of mobility on call block, call drops and optimal cell size in small cell networks

    OpenAIRE

    Ramanath , Sreenath; Voleti , Veeraruna Kavitha; Altman , Eitan

    2011-01-01

    We consider small cell networks and study the impact of user mobility. Assuming Poisson call arrivals at random positions with random velocities, we discuss the characterization of handovers at the boundaries. We derive explicit expressions for call block and call drop probabilities using tools from spatial queuing theory. We also derive expressions for the average virtual server held up time. These expressions are used to derive optimal cell sizes for various profile of velocities in small c...

  16. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    International Nuclear Information System (INIS)

    Liu Pengpeng; Guan Rongfa; Jiang Jiaxin; Liu Mingqi; Huang Guangrong; Chen Xiaoting; Ye Xingqian

    2011-01-01

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL -1 . LDH leakage significantly increased in cells exposed to Ag NPs (≥ 25 μg mL -1 ) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL -1 ). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

  17. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    Science.gov (United States)

    Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

    2011-07-01

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

  18. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    Energy Technology Data Exchange (ETDEWEB)

    Liu Pengpeng; Guan Rongfa; Jiang Jiaxin; Liu Mingqi; Huang Guangrong; Chen Xiaoting [Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences, China Jiliang University, Hangzhou 310018 (China); Ye Xingqian, E-mail: rfguan@163.com [Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029 (China)

    2011-07-06

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 {mu}g{center_dot}mL{sup -1}. LDH leakage significantly increased in cells exposed to Ag NPs ({>=} 25 {mu}g mL{sup -1}) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 {mu}g{center_dot}mL{sup -1}). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage

  19. Controlling the spotlight of attention: visual span size and flexibility in schizophrenia.

    Science.gov (United States)

    Elahipanah, Ava; Christensen, Bruce K; Reingold, Eyal M

    2011-10-01

    The current study investigated the size and flexible control of visual span among patients with schizophrenia during visual search performance. Visual span is the region of the visual field from which one extracts information during a single eye fixation, and a larger visual span size is linked to more efficient search performance. Therefore, a reduced visual span may explain patients' impaired performance on search tasks. The gaze-contingent moving window paradigm was used to estimate the visual span size of patients and healthy participants while they performed two different search tasks. In addition, changes in visual span size were measured as a function of two manipulations of task difficulty: target-distractor similarity and stimulus familiarity. Patients with schizophrenia searched more slowly across both tasks and conditions. Patients also demonstrated smaller visual span sizes on the easier search condition in each task. Moreover, healthy controls' visual span size increased as target discriminability or distractor familiarity increased. This modulation of visual span size, however, was reduced or not observed among patients. The implications of the present findings, with regard to previously reported visual search deficits, and other functional and structural abnormalities associated with schizophrenia, are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Small-cell comb does not control Varroa mites in colonies of honeybees of European origin

    OpenAIRE

    Seeley , Thomas; Griffin , Sean

    2011-01-01

    International audience; We tested the idea that Varroa destructor can be controlled in colonies of the European subspecies of Apis mellifera by providing them with combs built of small cells, in which immature mites might have difficulty developing for lack of space. We established seven pairs of equal-size colonies that started out equally infested with mites. In each pair, one hive contained only standard-cell (5.4 mm) comb, and the other contained only small-cell (4.8 mm) comb. We measured...

  1. Size effects in olivine control strength in low-temperature plasticity regime

    Science.gov (United States)

    Kumamoto, K. M.; Thom, C.; Wallis, D.; Hansen, L. N.; Armstrong, D. E. J.; Goldsby, D. L.; Warren, J. M.; Wilkinson, A. J.

    2017-12-01

    The strength of the lithospheric mantle during deformation by low-temperature plasticity controls a range of geological phenomena, including lithospheric-scale strain localization, the evolution of friction on deep seismogenic faults, and the flexure of tectonic plates. However, constraints on the strength of olivine in this deformation regime are difficult to obtain from conventional rock-deformation experiments, and previous results vary considerably. We demonstrate via nanoindentation that the strength of olivine in the low-temperature plasticity regime is dependent on the length-scale of the test, with experiments on smaller volumes of material exhibiting larger yield stresses. This "size effect" has previously been explained in engineering materials as a result of the role of strain gradients and associated geometrically necessary dislocations in modifying plastic behavior. The Hall-Petch effect, in which a material with a small grain size exhibits a higher strength than one with a large grain size, is thought to arise from the same mechanism. The presence of a size effect resolves discrepancies among previous experimental measurements of olivine, which were either conducted using indentation methods or were conducted on polycrystalline samples with small grain sizes. An analysis of different low-temperature plasticity flow laws extrapolated to room temperature reveals a power-law relationship between length-scale (grain size for polycrystalline deformation and contact radius for indentation tests) and yield strength. This suggests that data from samples with large inherent length scales best represent the plastic strength of the coarse-grained lithospheric mantle. Additionally, the plastic deformation of nanometer- to micrometer-sized asperities on fault surfaces may control the evolution of fault roughness due to their size-dependent strength.

  2. Paleolatitudinal Gradients in Marine Phytoplankton Composition and Cell Size

    Science.gov (United States)

    Henderiks, J.; Bordiga, M.; Bartol, M.; Šupraha, L.

    2014-12-01

    Coccolithophores, a prominent group of marine calcifying unicellular algae, are widely studied in context of current and past climate change. We know that marine phytoplankton are sensitive to climatic changes, but the complex interplay of several processes such as warming, changes in nutrient content, and ocean acidification, makes future scenarios difficult to predict. Some taxa may be more susceptible to environmental perturbations than others, as evidenced by significantly different species-specific sensitivities observed in laboratory experiments. However, short-term plastic responses may not translate into longer-term climatic adaptation, nor should we readily extrapolate the behavior of single strains in the laboratory to natural, multi-species assemblages and their interactions in the ocean. The extensive fossil record of coccolithophores (in the form of coccoliths) reveals high morphological and taxonomic diversity and allows reconstructing the cell size of individual taxonomic groups. In a suite of deep-sea drilling sites from the Atlantic Ocean, we document distinct latitudinal gradients in phytoplankton composition and cell size across major climate transitions of the late Eocene - earliest Oligocene, and the middle - late Miocene. With these data we test hypotheses of species migration, phenotypic evolution, as well as the rates of species extinction and speciation in relation to concurrent paleoenvironmental changes during the Cenozoic.

  3. Detonation cell size measurements in high-temperature hydrogen-air-steam mixtures at the BNL high-temperature combustion facility

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Ginsberg, T.; Boccio, J.L.

    1997-11-01

    The High-Temperature Combustion Facility (HTCF) was designed and constructed with the objective of studying detonation phenomena in mixtures of hydrogen-air-steam at initially high temperatures. The central element of the HTCF is a 27-cm inner-diameter, 21.3-m long cylindrical test vessel capable of being heating to 700K ± 14K. A unique feature of the HTCF is the 'diaphragmless' acetylene-oxygen gas driver which is used to initiate the detonation in the test gas. Cell size measurements have shown that for any hydrogen-air-steam mixture, increasing the initial mixture temperature, in the range of 300K to 650K, while maintaining the initial pressure of 0.1 MPa, decreases the cell size and thus makes the mixture more detonable. The effect of steam dilution on cell size was tested in stoichiometric and off-stoichiometric (e.g., equivalence ratio of 0.5) hydrogen-air mixtures. Increasing the steam dilution in hydrogen-air mixtures at 0.1 MPa initial pressure increases the cell size, irrespective of initial temperature. It is also observed that the desensitizing effect of steam diminished with increased initial temperature. A 1-dimensional, steady-state Zel'dovich, von Neumann, Doring (ZND) model, with full chemical kinetics, has been used to predict cell size for hydrogen-air-steam mixtures at different initial conditions. Qualitatively the model predicts the overall trends observed in the measured cell size versus mixture composition and initial temperature and pressure. It was found that the proportionality constant used to predict detonation cell size from the calculated ZND model reaction zone varies between 10 and 100 depending on the mixture composition and initial temperature. 32 refs., 35 figs

  4. Size-controlled fluorescent nanodiamonds: A facile method of fabrication and color-center counting

    KAUST Repository

    Mahfouz, Remi

    2013-01-01

    We present a facile method for the production of fluorescent diamond nanocrystals (DNCs) of different sizes and efficiently quantify the concentration of emitting defect color centers (DCCs) of each DNC size. We prepared the DNCs by ball-milling commercially available micrometer-sized synthetic (high pressure, high temperature (HPHT)) diamonds and then separated the as-produced DNCs by density gradient ultracentrifugation (DGU) into size-controlled fractions. A protocol to enhance the uniformity of the nitrogen-vacancy (NV) centers in the diamonds was devised by depositing the DNCs as a dense monolayer on amino-silanized silicon substrates and then subjecting the monolayer to He+ beam irradiation. Using a standard confocal setup, we analyzed the average number of NV centers per crystal, and obtained a quantitative relationship between the DNC particle size and the NV number per crystal. This relationship was in good agreement with results from previous studies that used more elaborate setups. Our findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color centers and new strategies to create them. © 2013 The Royal Society of Chemistry.

  5. The Size And Localisation Of Yellow Pigmented Lipid Cells 6 ...

    African Journals Online (AJOL)

    The size and distribution of the main pungent principle (6-gingerol) in two ginger varieties “ Tafin giwa” (the yellow variety) and “Yatsum biri” (the dark variety) at 4, 5, 6, and 8 months stages of maturity at harvest were studied empirically by the determination of the mean number of yellow pigmented lipid cells per unit area ...

  6. Size-based cell sorting with a resistive pulse sensor and an electromagnetic pump in a microfluidic chip.

    Science.gov (United States)

    Song, Yongxin; Li, Mengqi; Pan, Xinxiang; Wang, Qi; Li, Dongqing

    2015-02-01

    An electrokinetic microfluidic chip is developed to detect and sort target cells by size from human blood samples. Target-cell detection is achieved by a differential resistive pulse sensor (RPS) based on the size difference between the target cell and other cells. Once a target cell is detected, the detected RPS signal will automatically actuate an electromagnetic pump built in a microchannel to push the target cell into a collecting channel. This method was applied to automatically detect and sort A549 cells and T-lymphocytes from a peripheral fingertip blood sample. The viability of A549 cells sorted in the collecting well was verified by Hoechst33342 and propidium iodide staining. The results show that as many as 100 target cells per minute can be sorted out from the sample solution and thus is particularly suitable for sorting very rare target cells, such as circulating tumor cells. The actuation of the electromagnetic valve has no influence on RPS cell detection and the consequent cell-sorting process. The viability of the collected A549 cell is not impacted by the applied electric field when the cell passes the RPS detection area. The device described in this article is simple, automatic, and label-free and has wide applications in size-based rare target cell sorting for medical diagnostics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. On-Chip Production of Size-Controllable Liquid Metal Microdroplets Using Acoustic Waves.

    Science.gov (United States)

    Tang, Shi-Yang; Ayan, Bugra; Nama, Nitesh; Bian, Yusheng; Lata, James P; Guo, Xiasheng; Huang, Tony Jun

    2016-07-01

    Micro- to nanosized droplets of liquid metals, such as eutectic gallium indium (EGaIn) and Galinstan, have been used for developing a variety of applications in flexible electronics, sensors, catalysts, and drug delivery systems. Currently used methods for producing micro- to nanosized droplets of such liquid metals possess one or several drawbacks, including the lack in ability to control the size of the produced droplets, mass produce droplets, produce smaller droplet sizes, and miniaturize the system. Here, a novel method is introduced using acoustic wave-induced forces for on-chip production of EGaIn liquid-metal microdroplets with controllable size. The size distribution of liquid metal microdroplets is tuned by controlling the interfacial tension of the metal using either electrochemistry or electrocapillarity in the acoustic field. The developed platform is then used for heavy metal ion detection utilizing the produced liquid metal microdroplets as the working electrode. It is also demonstrated that a significant enhancement of the sensing performance is achieved by introducing acoustic streaming during the electrochemical experiments. The demonstrated technique can be used for developing liquid-metal-based systems for a wide range of applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Size-controllable synthesis of bare gold nanoparticles by femtosecond laser fragmentation in water

    International Nuclear Information System (INIS)

    Maximova, Ksenia; Aristov, Andrei; Sentis, Marc; Kabashin, Andrei V

    2015-01-01

    We report a size-controllable synthesis of stable aqueous solutions of ultrapure low-size-dispersed Au nanoparticles by methods of femtosecond laser fragmentation from preliminary formed colloids. Such approach makes possible the tuning of mean nanoparticle size between a few nm and several tens of nm under the size dispersion lower than 70% by varying the fluence of pumping radiation during the fragmentation procedure. The efficient size control is explained by 3D geometry of laser fragmentation by femtosecond laser-induced white light super-continuum and plasma-related phenomena. Despite the absence of any protective ligands, the nanoparticle solutions demonstrate exceptional stability due to electric repulsion effect associated with strong negative charging of formed nanoparticles. Stable aqueous solutions of bare gold nanoparticles present a unique object with a variety of potential applications in catalysis, surface-enhanced Raman spectroscopy, photovoltaics, biosensing and biomedicine. (paper)

  9. Dynamic Modeling, Model-Based Control, and Optimization of Solid Oxide Fuel Cells

    Science.gov (United States)

    Spivey, Benjamin James

    2011-07-01

    Solid oxide fuel cells are a promising option for distributed stationary power generation that offers efficiencies ranging from 50% in stand-alone applications to greater than 80% in cogeneration. To advance SOFC technology for widespread market penetration, the SOFC should demonstrate improved cell lifetime and load-following capability. This work seeks to improve lifetime through dynamic analysis of critical lifetime variables and advanced control algorithms that permit load-following while remaining in a safe operating zone based on stress analysis. Control algorithms typically have addressed SOFC lifetime operability objectives using unconstrained, single-input-single-output control algorithms that minimize thermal transients. Existing SOFC controls research has not considered maximum radial thermal gradients or limits on absolute temperatures in the SOFC. In particular, as stress analysis demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs. This dissertation presents a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop control simulations. A constrained, MIMO model predictive control algorithm is developed and applied to control the SOFC. Closed-loop control simulation results demonstrate effective load-following, constraint satisfaction for critical lifetime variables, and disturbance rejection. Nonlinear programming is applied to find the optimal SOFC size and steady-state operating conditions to minimize total system costs.

  10. Improved timestep-size diagnostic edits for TRAC-P

    International Nuclear Information System (INIS)

    Giguere, P.T.

    1996-04-01

    Improvements have been made to the timestep-size selection logic diagnostic edits of the Transient Reactor Analysis Code (TRAC), specifically to the TRAC-P version. These include both a precise account of the reason for the selection for individual timesteps and thermal-hydraulic information on mesh cells that control the timestep size. The new edits can be specified by user input as a range of timestep numbers, problem time, or both. A description of the current timestep controls in effect in TRAC-P is also given

  11. Improved timestep-size diagnostic edits for TRAC-P

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, P.T. [Los Alamos National Lab., NM (United States). Technology and Safety Assessment Div.

    1996-04-01

    Improvements have been made to the timestep-size selection logic diagnostic edits of the Transient Reactor Analysis Code (TRAC), specifically to the TRAC-P version. These include both a precise account of the reason for the selection for individual timesteps and thermal-hydraulic information on mesh cells that control the timestep size. The new edits can be specified by user input as a range of timestep numbers, problem time, or both. A description of the current timestep controls in effect in TRAC-P is also given.

  12. Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells.

    Science.gov (United States)

    Kourkoutis, Lena F; Hao, Xiaojing; Huang, Shujuan; Puthen-Veettil, Binesh; Conibeer, Gavin; Green, Martin A; Perez-Wurfl, Ivan

    2013-08-21

    All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.

  13. Control of beam size and polarization time in PEP

    International Nuclear Information System (INIS)

    Paterson, J.M.; Rees, J.R.; Wiedemann, H.

    1975-07-01

    In this report we describe a method of controlling beam size in which the focusing functions are not altered with beam energy but the curvature function is drastically altered in a few locations which comprise only a very small fraction of the circumference. As will be described in the following paper we are proposing to control the quantum excitation and radiation damping of the particles by means of special excitation magnets or /open quotes/wigglers/close quotes/. Since the mean square energy deviation and radial beam emittance are proportional approximately to E/sup 2//l angle/G/sup 3//r angle//l angle/G/sup 2//r angle//sup /minus/1 while the damping times are proportional to (E/sup 3//l angle/G/sup 2//r angle/)/sup /minus/1/, it is possible to achieve constant beam size in a constant focusing configuration while the damping times vary roughly as E/sup /minus/2/. In addition, it is possible to reduce the beam polarization time with these devices. A scheme for beam-size and damping control based on the same principle was described by M. Bassetti about a year ago, in which all of the storage-ring bending magnets were involved as wigglers, and a substantial increase in magnet cost resulted. The consequences for polarization times were not explored. The design formulae are derived and two specific applications to the PEP design in which the wigglers are installed in three of the six 5-m straight sections are described with attention given to practical magnet design, synchrotron radiation handling and other matters. 5 refs., 4 figs., 1 tab

  14. Cell-size distribution and scaling in a one-dimensional Kolmogorov-Johnson-Mehl-Avrami lattice model with continuous nucleation

    Science.gov (United States)

    Néda, Zoltán; Járai-Szabó, Ferenc; Boda, Szilárd

    2017-10-01

    The Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth model is considered on a one-dimensional (1D) lattice. Cells can grow with constant speed and continuously nucleate on the empty sites. We offer an alternative mean-field-like approach for describing theoretically the dynamics and derive an analytical cell-size distribution function. Our method reproduces the same scaling laws as the KJMA theory and has the advantage that it leads to a simple closed form for the cell-size distribution function. It is shown that a Weibull distribution is appropriate for describing the final cell-size distribution. The results are discussed in comparison with Monte Carlo simulation data.

  15. Survival of alpha particle irradiated cells as a function of the shape and size of the sensitive volume (nucleus)

    International Nuclear Information System (INIS)

    Stinchcomb, T.G.; Roeske, J.C.

    1995-01-01

    Microdosimetry is the study of the stochastic variation of energy deposited within sub-cellular targets. As such, the size and shape of the critical target (i.e. cell nucleus) are essential when considering microdosimetric quantities. In this work, a microdosimetric analysis examines the expected cell survival as a function of the size and shape of the cell nucleus under conditions of irradiation emitting alpha particles. The results indicate that, in general, cell survival is relatively insensitive to changes in the shape of the cell nucleus when the volume is held constant. However, cell survival is a strong function of the variation in the size of the target. These results are useful when analysing the results of cell survival experiments for alpha particle emitters. (Author)

  16. Human regulatory B cells control the TFH cell response.

    Science.gov (United States)

    Achour, Achouak; Simon, Quentin; Mohr, Audrey; Séité, Jean-François; Youinou, Pierre; Bendaoud, Boutahar; Ghedira, Ibtissem; Pers, Jacques-Olivier; Jamin, Christophe

    2017-07-01

    Follicular helper T (T FH ) cells support terminal B-cell differentiation. Human regulatory B (Breg) cells modulate cellular responses, but their control of T FH cell-dependent humoral immune responses is unknown. We sought to assess the role of Breg cells on T FH cell development and function. Human T cells were polyclonally stimulated in the presence of IL-12 and IL-21 to generate T FH cells. They were cocultured with B cells to induce their terminal differentiation. Breg cells were included in these cultures, and their effects were evaluated by using flow cytometry and ELISA. B-cell lymphoma 6, IL-21, inducible costimulator, CXCR5, and programmed cell death protein 1 (PD-1) expressions increased on stimulated human T cells, characterizing T FH cell maturation. In cocultures they differentiated B cells into CD138 + plasma and IgD - CD27 + memory cells and triggered immunoglobulin secretions. Breg cells obtained by Toll-like receptor 9 and CD40 activation of B cells prevented T FH cell development. Added to T FH cell and B-cell cocultures, they inhibited B-cell differentiation, impeded immunoglobulin secretions, and expanded Foxp3 + CXCR5 + PD-1 + follicular regulatory T cells. Breg cells modulated IL-21 receptor expressions on T FH cells and B cells, and their suppressive activities involved CD40, CD80, CD86, and intercellular adhesion molecule interactions and required production of IL-10 and TGF-β. Human Breg cells control T FH cell maturation, expand follicular regulatory T cells, and inhibit the T FH cell-mediated antibody secretion. These novel observations demonstrate a role for the Breg cell in germinal center reactions and suggest that deficient activities might impair the T FH cell-dependent control of humoral immunity and might lead to the development of aberrant autoimmune responses. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  17. Changes in the oligomerization potential of the division inhibitor UgtP co-ordinate Bacillus subtilis cell size with nutrient availability.

    Science.gov (United States)

    Chien, An-Chun; Zareh, Shannon Kian Gharabiklou; Wang, Yan Mei; Levin, Petra Anne

    2012-11-01

    How cells co-ordinate size with growth and development is a major, unresolved question in cell biology. In previous work we identified the glucosyltransferase UgtP as a division inhibitor responsible for increasing the size of Bacillus subtilis cells under nutrient-rich conditions. In nutrient-rich medium, UgtP is distributed more or less uniformly throughout the cytoplasm and concentrated at the cell poles and/or the cytokinetic ring. Under these conditions, UgtP interacts directly with FtsZ to inhibit division and increase cell size. Conversely, under nutrient-poor conditions, UgtP is sequestered away from FtsZ in punctate foci, and division proceeds unimpeded resulting in a reduction in average cell size. Here we report that nutrient-dependent changes in UgtP's oligomerization potential serve as a molecular rheostat to precisely co-ordinate B. subtilis cell size with nutrient availability. Our data indicate UgtP interacts with itself and the essential cell division protein FtsZ in a high-affinity manner influenced in part by UDP glucose, an intracellular proxy for nutrient availability. These findings support a model in which UDP-glc-dependent changes in UgtP's oligomerization potential shift the equilibrium between UgtP•UgtP and UgtP•FtsZ, fine-tuning the amount of FtsZ available for assembly into the cytokinetic ring and with it cell size. © 2012 Blackwell Publishing Ltd.

  18. Convergence of Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size

    Science.gov (United States)

    2018-03-01

    SiC with Computational Cell Size by Ariana Beste and DeCarlos E Taylor Approved for public release; distribution is unlimited...Laboratory Convergence of Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size by Ariana Beste...Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  19. Carbon-coated NiPt, CoPt nanoalloys: size control and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    El-Gendy, A.A. [Kirchhoff Institute for Physics, University of Heidelberg, D-69120 Heidelberg (Germany); Leibniz Institute for Solid State and Materials Research (IFW) Dresden (Germany); Hampel, S.; Leonhardt, A.; Khavrus, V.; Buechner, B. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden (Germany); Klingeler, R. [Kirchhoff Institute for Physics, University of Heidelberg, D-69120 Heidelberg (Germany)

    2011-07-01

    Controlled synthesis of magnetic nanoparticles with well-defined size and composition is always a challenge in material-based nanoscience. Here, we apply the high pressure chemical vapour deposition technique (HPCVD) to obtain carbon-shielded magnetic alloy nanoparticles under control of the particle size. Carbon encapsulated NiPt, CoPt (NiPt rate at C, CoPt rate at C) nanoalloys were synthesized by means of HPCVD starting from sublimating appropriate metal-organic precursors. Structural characterization by means of high resolution transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction indicated the formation of coated bimetallic Ni{sub x}Pt{sub 100-x} and CoxPt{sub 100-x} nanoparticles. Adjusting the sublimation temperature of the different precursors allowed tuning the core sizes with small size distribution. In addition, detailed studies of the magnetic properties are presented. AC magnetic heating studies imply the potential of the coated nanoalloys for hyperthermia therapy.

  20. Particle Size-Dependent Antibacterial Activity and Murine Cell Cytotoxicity Induced by Graphene Oxide Nanomaterials

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2016-01-01

    Full Text Available Recent studies have indicated that graphene and its derivative graphene oxide (GO engage in a wide range of antibacterial activities with limited toxicity to human cells. Here, we systematically evaluate the dependence of GO toxicity on the size of the nanoparticles used in treatments: we compare the cytotoxic effects of graphene quantum dots (GQDs, <15 nm, small GOs (SGOs, 50–200 nm, and large GOs (LGOs, 0.5–3 μm. We synthesize the results of bacterial colony count assays and SEM-based observations of morphological changes to assess the antibacterial properties that these GOs bring into effect against E. coli. We also use Live/Dead assays and morphological analysis to investigate changes to mammalian (Murine macrophage-like Raw 264.7 cells induced by the presence of the various GO particle types. Our results demonstrate that LGOs, SGOs, and GQDs possess antibacterial activities and cause mammalian cell cytotoxicity at descending levels of potency. Placing our observations in the context of previous simulation results, we suggest that both the lateral size and surface area of GO particles contribute to cytotoxic effects. We hope that the size dependence elucidated here provides a useful schematic for tuning GO-cell interactions in biomedical applications.

  1. Effects of growth rate, cell size, motion, and elemental stoichiometry on nutrient transport kinetics.

    Science.gov (United States)

    Flynn, Kevin J; Skibinski, David O F; Lindemann, Christian

    2018-04-01

    Nutrient acquisition is a critical determinant for the competitive advantage for auto- and osmohetero- trophs alike. Nutrient limited growth is commonly described on a whole cell basis through reference to a maximum growth rate (Gmax) and a half-saturation constant (KG). This empirical application of a Michaelis-Menten like description ignores the multiple underlying feedbacks between physiology contributing to growth, cell size, elemental stoichiometry and cell motion. Here we explore these relationships with reference to the kinetics of the nutrient transporter protein, the transporter rate density at the cell surface (TRD; potential transport rate per unit plasma-membrane area), and diffusion gradients. While the half saturation value for the limiting nutrient increases rapidly with cell size, significant mitigation is afforded by cell motion (swimming or sedimentation), and by decreasing the cellular carbon density. There is thus potential for high vacuolation and high sedimentation rates in diatoms to significantly decrease KG and increase species competitive advantage. Our results also suggest that Gmax for larger non-diatom protists may be constrained by rates of nutrient transport. For a given carbon density, cell size and TRD, the value of Gmax/KG remains constant. This implies that species or strains with a lower Gmax might coincidentally have a competitive advantage under nutrient limited conditions as they also express lower values of KG. The ability of cells to modulate the TRD according to their nutritional status, and hence change the instantaneous maximum transport rate, has a very marked effect upon transport and growth kinetics. Analyses and dynamic models that do not consider such modulation will inevitably fail to properly reflect competitive advantage in nutrient acquisition. This has important implications for the accurate representation and predictive capabilities of model applications, in particular in a changing environment.

  2. TiO2 nanoparticles disrupt cell adhesion and the architecture of cytoskeletal networks of human osteoblast-like cells in a size dependent manner.

    Science.gov (United States)

    Ibrahim, Mohamed; Schoelermann, Julia; Mustafa, Kamal; Cimpan, Mihaela R

    2018-04-30

    Human exposure to titanium dioxide nanoparticles (nano-TiO 2 ) is increasing. An internal source of nano-TiO 2 is represented by titanium-based orthopedic and dental implants can release nanoparticles (NPs) upon abrasion. Little is known about how the size of NPs influences their interaction with cytoskeletal protein networks and the functional/homeostatic consequences that might follow at the implant-bone interface with regard to osteoblasts. We investigated the effects of size of anatase nano-TiO 2 on SaOS-2 human osteoblast-like cells exposed to clinically relevant concentrations (0.05, 0.5, 5 mg/L) of 5 and 40 nm spherical nano-TiO 2 . Cell viability and proliferation, adhesion, spread and migration were assessed, as well as the orientation of actin and microtubule cytoskeletal networks. The phosphorylation of focal adhesion kinase (p-FAK Y397 ) and the expression of vinculin in response to nano-TiO 2 were also assessed. Treatment with nano-TiO 2 disrupted the actin and microtubule cytoskeletal networks leading to morphological modifications of SaOS-2 cells. The phosphorylation of p-FAK Y397 and the expression of vinculin were also modified depending on the particle size, which affected cell adhesion. Consequently, the cell migration was significantly impaired in the 5 nm-exposed cells compared to unexposed cells. The present work shows that the orientation of cytoskeletal networks and the focal adhesion proteins and subsequently the adhesion, spread and migration of SaOS-2 cells were affected by the selected nano-TiO 2 in a size dependent manner. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

  3. Using Micromanipulation to Analyze Control of Vertebrate Meiotic Spindle Size

    Directory of Open Access Journals (Sweden)

    Jun Takagi

    2013-10-01

    Full Text Available The polymerization/depolymerization dynamics of microtubules (MTs have been reported to contribute to control of the size and shape of spindles, but quantitative analysis of how the size and shape correlate with the amount and density of MTs in the spindle remains incomplete. Here, we measured these parameters using 3D microscopy of meiotic spindles that self-organized in Xenopus egg extracts and presented a simple equation describing the relationship among these parameters. To examine the validity of the equation, we cut the spindle into two fragments along the pole-to-pole axis by micromanipulation techniques that rapidly decrease the amount of MTs. The spheroidal shape spontaneously recovered within 5 min, but the size of each fragment remained small. The equation we obtained quantitatively describes how the spindle size correlates with the amount of MTs while maintaining the shape and the MT density.

  4. Cell Size Influences the Reproductive Potential and Total Lifespan of the Saccharomyces cerevisiae Yeast as Revealed by the Analysis of Polyploid Strains

    Directory of Open Access Journals (Sweden)

    Renata Zadrag-Tecza

    2018-01-01

    Full Text Available The total lifespan of the yeast Saccharomyces cerevisiae may be divided into two phases: the reproductive phase, during which the cell undergoes mitosis cycles to produce successive buds, and the postreproductive phase, which extends from the last division to cell death. These phases may be regulated by a common mechanism or by distinct ones. In this paper, we proposed a more comprehensive approach to reveal the mechanisms that regulate both reproductive potential and total lifespan in cell size context. Our study was based on yeast cells, whose size was determined by increased genome copy number, ranging from haploid to tetraploid. Such experiments enabled us to test the hypertrophy hypothesis, which postulates that excessive size achieved by the cell—the hypertrophy state—is the reason preventing the cell from further proliferation. This hypothesis defines the reproductive potential value as the difference between the maximal size that a cell can reach and the threshold value, which allows a cell to undergo its first cell cycle and the rate of the cell size to increase per generation. Here, we showed that cell size has an important impact on not only the reproductive potential but also the total lifespan of this cell. Moreover, the maximal cell size value, which limits its reproduction capacity, can be regulated by different factors and differs depending on the strain ploidy. The achievement of excessive size by the cell (hypertrophic state may lead to two distinct phenomena: the cessation of reproduction without “mother” cell death and the cessation of reproduction with cell death by bursting, which has not been shown before.

  5. The Functionalization, Size Control and Properties of Metal-Organic Frameworks

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size....... A nanoscale MOF material with controllable size was realized whose morphology has been simulated base on the BFDH method, and the sensing of bacteria endospores was research in detail. We also report the synthesis and sensing of nitroaromatic explosives of a nanoscale MOF material....

  6. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    International Nuclear Information System (INIS)

    Zaki, S. S. O.; Ibrahim, M. N.; Katas, H.

    2015-01-01

    Chitosan nanoparticles (CSNPs) have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs). CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential). Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW)). Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  7. Confinement of surface waves at the air-water interface to control aerosol size and dispersity

    Science.gov (United States)

    Nazarzadeh, Elijah; Wilson, Rab; King, Xi; Reboud, Julien; Tassieri, Manlio; Cooper, Jonathan M.

    2017-11-01

    The precise control over the size and dispersity of droplets, produced within aerosols, is of great interest across many manufacturing, food, cosmetic, and medical industries. Amongst these applications, the delivery of new classes of high value drugs to the lungs has recently attracted significant attention from pharmaceutical companies. This is commonly achieved through the mechanical excitation of surface waves at the air liquid interface of a parent liquid volume. Previous studies have established a correlation between the wavelength on the surface of liquid and the final aerosol size. In this work, we show that the droplet size distribution of aerosols can be controlled by constraining the liquid inside micron-sized cavities and coupling surface acoustic waves into different volumes of liquid inside micro-grids. In particular, we show that by reducing the characteristic physical confinement size (i.e., either the initial liquid volume or the cavities' diameters), higher harmonics of capillary waves are revealed with a consequent reduction of both aerosol mean size and dispersity. In doing so, we provide a new method for the generation and fine control of aerosols' sizes distribution.

  8. ISABELLE half-cell control system

    International Nuclear Information System (INIS)

    Buxton, W.; Frankel, R.; Humphrey, J.W.

    1977-01-01

    The primary function of the ISABELLE half-cell control system is to monitor and control the magnet power supplies of the half-cell. In addition, the control system must be flexible enough that it can be expanded to become involved in additional areas such as vacuum and magnetic measurements. A control system based upon AGS control standards, but modified into a development tool for research and electrical engineering support was constructed. Special attention was given to the inherent differences between controlling an ISABELLE and a conventional fast cycling accelerator. The use of FORTRAN and BASIC networks, and microprocessors is reviewed insofar as they pertain to this system. Some general opinions on model control systems, based upon experience, are presented

  9. Magnetogenetic control of protein gradients inside living cells with high spatial and temporal resolution.

    Science.gov (United States)

    Etoc, Fred; Vicario, Chiara; Lisse, Domenik; Siaugue, Jean-Michel; Piehler, Jacob; Coppey, Mathieu; Dahan, Maxime

    2015-05-13

    Tools for controlling the spatial organization of proteins are a major prerequisite for deciphering mechanisms governing the dynamic architecture of living cells. Here, we have developed a generic approach for inducing and maintaining protein gradients inside living cells by means of biofunctionalized magnetic nanoparticles (MNPs). For this purpose, we tailored the size and surface properties of MNPs in order to ensure unhindered mobility in the cytosol. These MNPs with a core diameter below 50 nm could be rapidly relocalized in living cells by exploiting biased diffusion at weak magnetic forces in the femto-Newton range. In combination with MNP surface functionalization for specific in situ capturing of target proteins as well as efficient delivery into the cytosplasm, we here present a comprehensive technology for controlling intracellular protein gradients with a temporal resolution of a few tens of seconds.

  10. Naevi as a risk factor for basal cell carcinoma in Caucasians: a Danish case-control study

    DEFF Research Database (Denmark)

    Lock-Andersen, J; Drzewiecki, K T; Wulf, H C

    1999-01-01

    The number of melanocytic naevi in Caucasians is related to previous exposure to the sun and is a well-documented major risk factor for cutaneous malignant melanoma. Basal cell carcinoma, which is the most common form of skin cancer, has also been shown to be related to exposure to the sun....... To investigate whether the number of common naevi is a risk factor for basal cell carcinoma in Caucasians we performed whole-body counting of naevi > or =2 mm in a Danish case-control study with 145 cases of primary basal cell carcinoma and 119 controls matched on age, gender and place of residence. Naevi were...... recorded according to size and body region and the skin phototype was assessed. There was no correlation between self-reported skin type and the number of naevi. Females with basal cell carcinoma had more naevi than did female controls (median number of naevi: 65 and 32, respectively) while males...

  11. crm-1 facilitates BMP signaling to control body size in Caenorhabditis elegans.

    Science.gov (United States)

    Fung, Wong Yan; Fat, Ko Frankie Chi; Eng, Cheah Kathryn Song; Lau, Chow King

    2007-11-01

    We have identified in Caenorhabditis elegans a homologue of the vertebrate Crim1, crm-1, which encodes a putative transmembrane protein with multiple cysteine-rich (CR) domains known to have bone morphogenetic proteins (BMPs) binding activity. Using the body morphology of C. elegans as an indicator, we showed that attenuation of crm-1 activity leads to a small body phenotype reminiscent of that of BMP pathway mutants. We showed that the crm-1 loss-of-function phenotype can be rescued by constitutive supply of sma-4 activity. crm-1 can enhance BMP signaling and this activity is dependent on the presence of the DBL-1 ligand and its receptors. crm-1 is expressed in neurons at the ventral nerve cord, where the DBL-1 ligand is produced. However, ectopic expression experiments reveal that crm-1 gene products act outside the DBL-1 producing cells and function non-autonomously to facilitate dbl/sma pathway signaling to control body size.

  12. U-Mo Alloy Powder Obtained Through Selective Hydriding. Particle Size Control

    International Nuclear Information System (INIS)

    Balart, S.N.; Bruzzoni, P.; Granovsky, M.S.

    2002-01-01

    Hydride-dehydride methods to obtain U-Mo alloy powder for high-density fuel elements have been successfully tested by different authors. One of these methods is the selective hydriding of the α phase (HSα). In the HSα method, a key step is the partial decomposition of the γ phase (retained by quenching) to α phase and an enriched γ phase or U 2 Mo. This transformation starts mainly at grain boundaries. Subsequent hydrogenation of this material leads to selective hydriding of the α phase, embrittlement and intergranular fracture. According to this picture, the particle size of the final product should be related to the γ grain size of the starting alloy. The feasibility of controlling the particle size of the product by changing the γ grain size of the starting alloy is currently investigated. In this work an U-7 wt% Mo alloy was subjected to various heat treatments in order to obtain different grain sizes. The results on the powder particle size distribution after applying the HSα method to these samples show that there is a strong correlation between the original γ grain size and the particle size distribution of the powder. (author)

  13. Uniform TiO2 nanoparticles induce apoptosis in epithelial cell lines in a size-dependent manner.

    Science.gov (United States)

    Sun, Qingqing; Ishii, Takayuki; Kanehira, Koki; Sato, Takeshi; Taniguchi, Akiyoshi

    2017-05-02

    The size of titanium dioxide (TiO 2 ) nanoparticles is a vital parameter that determines their cytotoxicity. However, most reported studies have employed irregular shapes and sizes of TiO 2 nanoparticles, as it is difficult to produce nanoparticles of suitable sizes for research. We produced good model TiO 2 nanoparticles of uniform shape and size for use in studying their cytotoxicity. In this work, spherical, uniform polyethylene glycol-modified TiO 2 (TiO 2 -PEG) nanoparticles of differing sizes (100, 200, and 300 nm) were prepared using the sol-gel method. A size-dependent decrease in cell viability was observed with increasing nanoparticle size. Furthermore, apoptosis was found to be positively associated with nanoparticle size, as evidenced by an increase in caspase-3 activity with increasing nanoparticle size. Larger nanoparticles exhibited higher cellular uptake, suggesting that larger nanoparticles more strongly induce apoptosis. In addition, the cellular uptake of different sizes of nanoparticles was energy dependent, suggesting that there are size-dependent uptake pathways. We found that 100 and 200 nm (but not 300 nm) nanoparticles were taken up via clathrin-mediated endocytosis. These results utilizing uniform nanoparticles suggest that the size-dependent cytotoxicity of nanoparticles involves active cellular uptake, caspase-3 activation, and apoptosis in the epithelial cell line (NCI-H292). These findings will hopefully aid in the future design and safe use of nanoparticles.

  14. Isotropic 2D quadrangle meshing with size and orientation control

    KAUST Repository

    Pellenard, Bertrand; Alliez, Pierre; Morvan, Jean-Marie

    2011-01-01

    We propose an approach for automatically generating isotropic 2D quadrangle meshes from arbitrary domains with a fine control over sizing and orientation of the elements. At the heart of our algorithm is an optimization procedure that, from a coarse

  15. Elevator Sizing, Placement, and Control-Relevant Tradeoffs for Hypersonic Vehicles

    Science.gov (United States)

    Dickeson, Jeffrey J.; Rodriguez, Armando A.; Sridharan, Srikanth; Korad, Akshay

    2010-01-01

    Within this paper, control-relevant vehicle design concepts are examined using a widely used 3 DOF (plus flexibility) nonlinear model for the longitudinal dynamics of a generic carrot-shaped scramjet powered hypersonic vehicle. The impact of elevator size and placement on control-relevant static properties (e.g. level-flight trimmable region, trim controls, Angle of Attack (AOA), thrust margin) and dynamic properties (e.g. instability and right half plane zero associated with flight path angle) are examined. Elevator usage has been examine for a class of typical hypersonic trajectories.

  16. Energy harvesting from organic liquids in micro-sized microbial fuel cells

    KAUST Repository

    Mink, J.E.

    2014-03-07

    Micro-sized microbial fuel cells (MFCs) are miniature energy harvesters that use bacteria to convert biomass from liquids into usable power. The key challenge is transitioning laboratory test beds into devices capable of producing high power using readily available fuel sources. Here, we present a pragmatic step toward advancing MFC applications through the fabrication of a uniquely mobile and inexpensive micro-sized device that can be fueled with human saliva. The 25-ll MFC was fabricated with graphene, a two-dimensional atomic crystal-structured material, as an anode for efficient current generation and with an air cathode for enabling the use of the oxygen present in air, making its operation completely mobile and free of the need for laboratory chemicals. With saliva as a fuel, the device produced higher current densities (1190 Am-3) than any previous aircathode micro-sized MFCs. The use of the graphene anode generated 40 times more power than that possible using a carbon cloth anode. Additional tests were performed using acetate, a conventional organic material, at high organic loadings that were comparable to those in saliva, and the results demonstrated a linear relationship between the organic loading and current. These findings open the door to saliva-powered applications of this fuel cell technology for Lab-on-a-Chip devices or portable point-of-care diagnostic devices. 2014 Nature Publishing Group All rights reserved 1884-4057/14.

  17. A microwell cell culture platform for the aggregation of pancreatic β-cells.

    Science.gov (United States)

    Bernard, Abigail B; Lin, Chien-Chi; Anseth, Kristi S

    2012-08-01

    Cell-cell contact between pancreatic β-cells is important for maintaining survival and normal insulin secretion. Various techniques have been developed to promote cell-cell contact between β-cells, but a simple yet robust method that affords precise control over three-dimensional (3D) β-cell cluster size has not been demonstrated. To address this need, we developed a poly(ethylene glycol) (PEG) hydrogel microwell platform using photolithography. This microwell cell-culture platform promotes the formation of 3D β-cell aggregates of defined sizes from 25 to 210 μm in diameter. Using this platform, mouse insulinoma 6 (MIN6) β-cells formed aggregates with cell-cell adherin junctions. These naturally formed cell aggregates with controllable sizes can be removed from the microwells for macroencapsulation, implantation, or other biological assays. When removed and subsequently encapsulated in PEG hydrogels, the aggregated cell clusters demonstrated improved cellular viability (>90%) over 7 days in culture, while the β-cells encapsulated as single cells maintained only 20% viability. Aggregated MIN6 cells also exhibited more than fourfold higher insulin secretion in response to a glucose challenge compared with encapsulated single β-cells. Further, the cell aggregates stained positively for E-cadherin, indicative of the formation of cell junctions. Using this hydrogel microwell cell-culture method, viable and functional β-cell aggregates of specific sizes were created, providing a platform from which other biologically relevant questions may be answered.

  18. Immunohistochemical study of hepatocyte, cholangiocyte and stem cell markers of hepatocellular carcinoma: the second report: relationship with tumor size and cell differentiation.

    Science.gov (United States)

    Kumagai, Arisa; Kondo, Fukuo; Sano, Keiji; Inoue, Masafumi; Fujii, Takeshi; Hashimoto, Masaji; Watanabe, Masato; Soejima, Yurie; Ishida, Tsuyoshi; Tokairin, Takuo; Saito, Koji; Sasajima, Yuko; Takahashi, Yoshihisa; Uozaki, Hiroshi; Fukusato, Toshio

    2016-07-01

    The purpose of this study is to investigate whether ordinary hepatocellular carcinomas (HCCs) show positivity of stem/progenitor cell markers and cholangiocyte markers during the process of tumor progression. Ninety-four HCC lesions no larger than 8 cm from 94 patients were immuno-histochemically studied using two hepatocyte markers (Hep par 1 and α-fetoprotein), five cholangiocyte markers (cytokeratin CK7, CK19, Muc1, epithelial membrane antigen and carcinoembryonic antigen) and three hepatic stem/progenitor cell markers (CD56, c-Kit and EpCAM). The tumors were classified into three groups by tumor size: S1, tumors were also classified according to tumor differentiation: well, moderately and poorly differentiated. The relationship between the positive ratios of these markers, tumor size and tumor differentiation was examined. The positive ratios of cholangiocyte markers tended to be higher in larger sized and more poorly differentiated tumors (except for CK7). The positive ratios of stem/progenitor cell markers tended to be higher in larger sized and more poorly differentiated tumors (except for c-Kit). Ordinary HCC can acquire the characteristic of positivity of cholangiocyte and stem/progenitor cell markers during the process of tumor progression. © 2016 The Authors. Journal of Hepato-Biliary-Pancreatic Sciences published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  19. Myonuclear transcription is responsive to mechanical load and DNA content but uncoupled from cell size during hypertrophy.

    Science.gov (United States)

    Kirby, Tyler J; Patel, Rooshil M; McClintock, Timothy S; Dupont-Versteegden, Esther E; Peterson, Charlotte A; McCarthy, John J

    2016-03-01

    Myofibers increase size and DNA content in response to a hypertrophic stimulus, thus providing a physiological model with which to study how these factors affect global transcription. Using 5-ethynyl uridine (EU) to metabolically label nascent RNA, we measured a sevenfold increase in myofiber transcription during early hypertrophy before a change in cell size and DNA content. The typical increase in myofiber DNA content observed at the later stage of hypertrophy was associated with a significant decrease in the percentage of EU-positive myonuclei; however, when DNA content was held constant by preventing myonuclear accretion via satellite cell depletion, both the number of transcriptionally active myonuclei and the amount of RNA generated by each myonucleus increased. During late hypertrophy, transcription did not scale with cell size, as smaller myofibers (transcriptional activity. Finally, transcription was primarily responsible for changes in the expression of genes known to regulate myofiber size. These findings show that resident myonuclei possess a significant reserve capacity to up-regulate transcription during hypertrophy and that myofiber transcription is responsive to DNA content but uncoupled from cell size during hypertrophy. © 2016 Kirby et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  20. An approach to define the effective lath size controlling yield strength of bainite

    International Nuclear Information System (INIS)

    Zhu Kangying; Bouaziz, Olivier; Oberbillig, Carla; Huang, Mingxin

    2010-01-01

    Research highlights: In this study, we developed a series of fully bainitic microstructures with negligible carbide precipitation in ultra-low carbon steels. Then, we investigated the microstructure by EBSD as well as their mechanical properties. It is found that the yield stress of such bainite is proportional to the inverse lath size defined with low boundary misorientation (2-7 deg.). We explained this by employing a theory which predicts the flow stress of deformed metals, assuming that both lath boundary and dislocation cell boundary have similar capability of being dislocation obstacles. - Abstract: A fully bainitic microstructure with negligible carbide precipitation is obtained in two ultra-low carbon steels. The size and misorientation of bainite laths are analysed by Electron Back Scattering Diffraction (EBSD). It is found that the yield stress of bainite is proportional to the inverse lath size defined with low boundary misorientation (2-7 deg.). This can be explained by a theory predicting the flow stress of deformed metals, assuming that both lath boundary and dislocation cell boundary have similar capability of being dislocation obstacles.

  1. Optimal sizing of plug-in fuel cell electric vehicles using models of vehicle performance and system cost

    International Nuclear Information System (INIS)

    Xu, Liangfei; Ouyang, Minggao; Li, Jianqiu; Yang, Fuyuan; Lu, Languang; Hua, Jianfeng

    2013-01-01

    Highlights: ► An analytical model for vehicle performance and power-train parameters. ► Quantitative relationships between vehicle performance and power-train parameters. ► Optimal sizing rules that help designing an optimal PEM fuel cell power-train. ► An on-road testing showing the performance of the proposed vehicle. -- Abstract: This paper presents an optimal sizing method for plug-in proton exchange membrane (PEM) fuel cell and lithium-ion battery (LIB) powered city buses. We propose a theoretical model describing the relationship between components’ parameters and vehicle performance. Analysis results show that within the working range of the electric motor, the maximal velocity and driving distance are influenced linearly by the parameters of the components, e.g. fuel cell efficiency, fuel cell output power, stored hydrogen mass, vehicle auxiliary power, battery capacity, and battery average resistance. Moreover, accelerating time is also linearly dependant on the abovementioned parameters, except of those of the battery. Next, we attempt to minimize fixed and operating costs by introducing an optimal sizing problem that uses as constraints the requirements on vehicle performance. By solving this problem, we attain several optimal sizing rules. Finally, we use these rules to design a plug-in PEM fuel cell city bus and present performance results obtained by on-road testing.

  2. Controlling Factors of Cell Design on Large-format Li-ion Battery Safety During Nail Penetration

    Directory of Open Access Journals (Sweden)

    Qing eWang

    2015-08-01

    Full Text Available In this paper we investigate the controlling design parameters of large-format Li-ion batteries on safety while undergoing nail penetration. We have identified three critical design parameters that control the safety during the nail penetration process: nail diameter, single sheet foil area, and cell capacity.Using commercial AutoLion software, we have investigated two typical design problems related to the selection of cell thickness and aspect ratio, namely: (1 the safety ramifications of increasing cell capacity via greater cell thickness for a fixed footprint, and (2 the effect of aspect ratio, or single sheet foil size, on safety at a given capacity. For a fixed footprint, our results indicate that the safety of the cell can be predicted by (Qcell Dnail^-0.5. For a given cell capacity, our results indicate that typically a larger single sheet foil area leads to a greater likelihood for thermal runaway due to its effect of making the heating more local in nature; however, for small cells (~ 5Ah and large nails (~ 20mm, the greater aspect ratio can lead to a safer cell, as the greater surface area strongly cools the global heating of the cell.

  3. Innervating sympathetic neurons regulate heart size and the timing of cardiomyocyte cell cycle withdrawal.

    Science.gov (United States)

    Kreipke, R E; Birren, S J

    2015-12-01

    Sympathetic drive to the heart is a key modulator of cardiac function and interactions between heart tissue and innervating sympathetic fibres are established early in development. Significant innervation takes place during postnatal heart development, a period when cardiomyocytes undergo a rapid transition from proliferative to hypertrophic growth. The question of whether these innervating sympathetic fibres play a role in regulating the modes of cardiomyocyte growth was investigated using 6-hydroxydopamine (6-OHDA) to abolish early sympathetic innervation of the heart. Postnatal chemical sympathectomy resulted in rats with smaller hearts, indicating that heart growth is regulated by innervating sympathetic fibres during the postnatal period. In vitro experiments showed that sympathetic interactions resulted in delays in markers of cardiomyocyte maturation, suggesting that changes in the timing of the transition from hyperplastic to hypertrophic growth of cardiomyocytes could underlie changes in heart size in the sympathectomized animals. There was also an increase in the expression of Meis1, which has been linked to cardiomyocyte cell cycle withdrawal, suggesting that sympathetic signalling suppresses cell cycle withdrawal. This signalling involves β-adrenergic activation, which was necessary for sympathetic regulation of cardiomyocyte proliferation and hypertrophy. The effect of β-adrenergic signalling on cardiomyocyte hypertrophy underwent a developmental transition. While young postnatal cardiomyocytes responded to isoproterenol (isoprenaline) with a decrease in cell size, mature cardiomyocytes showed an increase in cell size in response to the drug. Together, these results suggest that early sympathetic effects on proliferation modulate a key transition between proliferative and hypertrophic growth of the heart and contribute to the sympathetic regulation of adult heart size. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  4. Porosity and cell size control in alumina foam preparation by thermo-foaming of powder dispersions in molten sucrose

    Directory of Open Access Journals (Sweden)

    Sujith Vijayan

    2016-09-01

    Full Text Available The foaming characteristics of alumina powder dispersions in molten sucrose have been studied as a function of alumina powder to sucrose weight ratio (WA/S and foaming temperature. The increase in foaming temperature significantly decreases the foaming and foam setting time and increases the foam volume due to an increase in the rate of OH condensation as well as a decrease in the viscosity of the dispersion. Nevertheless, the foam collapses beyond a critical foaming temperature, which depends on the WA/S. The sintering shrinkage depends mainly on the WA/S and marginally on the foaming temperature. The porosity (83.4–94.6 vol.% and cell size (0.55–1.6 mm increase with an increase in foaming temperature (120–170 °C and a decrease in WA/S (0.8–1.6. The drastic decrease in compressive strength and modulus beyond a WA/S of 1.2 is due to the pores generated on the cell walls and struts as a result of particle agglomeration. Gibson and Ashby plots show large deviation with respect to the model constants ‘C’ and ‘n’, especially at higher alumina powder to sucrose weight ratios.

  5. Hippo/Yap signaling controls epithelial progenitor cell proliferation and differentiation in the embryonic and adult lung

    Science.gov (United States)

    Lange, Alexander W.; Sridharan, Anusha; Xu, Yan; Stripp, Barry R.; Perl, Anne-Karina; Whitsett, Jeffrey A.

    2015-01-01

    The Hippo/Yap pathway is a well-conserved signaling cascade that regulates cell proliferation and differentiation to control organ size and stem/progenitor cell behavior. Following airway injury, Yap was dynamically regulated in regenerating airway epithelial cells. To determine the role of Hippo signaling in the lung, the mammalian Hippo kinases, Mst1 and Mst2, were deleted in epithelial cells of the embryonic and mature mouse lung. Mst1/2 deletion in the fetal lung enhanced proliferation and inhibited sacculation and epithelial cell differentiation. The transcriptional inhibition of cell proliferation and activation of differentiation during normal perinatal lung maturation were inversely regulated following embryonic Mst1/2 deletion. Ablation of Mst1/2 from bronchiolar epithelial cells in the adult lung caused airway hyperplasia and altered differentiation. Inhibitory Yap phosphorylation was decreased and Yap nuclear localization and transcriptional targets were increased after Mst1/2 deletion, consistent with canonical Hippo/Yap signaling. YAP potentiated cell proliferation and inhibited differentiation of human bronchial epithelial cells in vitro. Loss of Mst1/2 and expression of YAP regulated transcriptional targets controlling cell proliferation and differentiation, including Ajuba LIM protein. Ajuba was required for the effects of YAP on cell proliferation in vitro. Hippo/Yap signaling regulates Ajuba and controls proliferation and differentiation of lung epithelial progenitor cells. PMID:25480985

  6. Sizing stack and battery of a fuel cell hybrid distribution truck

    NARCIS (Netherlands)

    Bram Veenhuizen; P. van den Bosch; T. Hofman; Edwin Tazelaar; Y. Shen

    2012-01-01

    An existing fuel cell hybrid distribution truck, built for demonstration purposes, is used as a case study to investigate the effect of stack (kW) and battery (kW, kWh) sizes on the hydrogen consumption of the vehicle. Three driving cycles, the NEDC for Low Power vehicles, CSC and JE05 cycle, define

  7. Assessing T cell clonal size distribution: a non-parametric approach.

    Science.gov (United States)

    Bolkhovskaya, Olesya V; Zorin, Daniil Yu; Ivanchenko, Mikhail V

    2014-01-01

    Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity.

  8. Nanometer-scale sizing accuracy of particle suspensions on an unmodified cell phone using elastic light scattering.

    Science.gov (United States)

    Smith, Zachary J; Chu, Kaiqin; Wachsmann-Hogiu, Sebastian

    2012-01-01

    We report on the construction of a Fourier plane imaging system attached to a cell phone. By illuminating particle suspensions with a collimated beam from an inexpensive diode laser, angularly resolved scattering patterns are imaged by the phone's camera. Analyzing these patterns with Mie theory results in predictions of size distributions of the particles in suspension. Despite using consumer grade electronics, we extracted size distributions of sphere suspensions with better than 20 nm accuracy in determining the mean size. We also show results from milk, yeast, and blood cells. Performing these measurements on a portable device presents opportunities for field-testing of food quality, process monitoring, and medical diagnosis.

  9. Particle size distribution control of Pt particles used for particle gun

    Science.gov (United States)

    Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

    2017-07-01

    The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

  10. Size- and time-dependent growth properties of human induced pluripotent stem cells in the culture of single aggregate.

    Science.gov (United States)

    Nath, Suman C; Horie, Masanobu; Nagamori, Eiji; Kino-Oka, Masahiro

    2017-10-01

    Aggregate culture of human induced pluripotent stem cells (hiPSCs) is a promising method to obtain high number of cells for cell therapy applications. This study quantitatively evaluated the effects of initial cell number and culture time on the growth of hiPSCs in the culture of single aggregate. Small size aggregates ((1.1 ± 0.4) × 10 1 -(2.8 ± 0.5) × 10 1 cells/aggregate) showed a lower growth rate in comparison to medium size aggregates ((8.8 ± 0.8) × 10 1 -(6.8 ± 1.1) × 10 2 cells/aggregate) during early-stage of culture (24-72 h). However, when small size aggregates were cultured in conditioned medium, their growth rate increased significantly. On the other hand, large size aggregates ((1.1 ± 0.2) × 10 3 -(3.5 ± 1.1) × 10 3 cells/aggregate) showed a lower growth rate and lower expression level of proliferation marker (ki-67) in the center region of aggregate in comparison to medium size aggregate during early-stage of culture. Medium size aggregates showed the highest growth rate during early-stage of culture. Furthermore, hiPSCs proliferation was dependent on culture time because the growth rate decreased significantly during late-stage of culture (72-120 h) at which point collagen type I accumulated on the periphery of aggregate, suggesting blockage of diffusive transport of nutrients, oxygen and metabolites into and out of the aggregates. Consideration of initial cell number and culture time are important to maintain balance between autocrine factors secretion and extracellular matrix accumulation on the aggregate periphery to achieve optimal growth of hiPSCs in the culture of single aggregate. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  11. Experimental study of commercial size proton exchange membrane fuel cell performance

    International Nuclear Information System (INIS)

    Yan, Wei-Mon; Wang, Xiao-Dong; Lee, Duu-Jong; Zhang, Xin-Xin; Guo, Yi-Fan; Su, Ay

    2011-01-01

    Commercial sized (16 x 16 cm 2 active surface area) proton exchange membrane (PEM) fuel cells with serpentine flow chambers are fabricated. The GORE-TEX (registered) PRIMEA 5621 was used with a 35-μm-thick PEM with an anode catalyst layer with 0.45 mg cm -2 Pt and cathode catalyst layer with 0.6 mg cm -2 Pt and Ru or GORE-TEX (registered) PRIMEA 57 was used with an 18-μm-thick PEM with an anode catalyst layer at 0.2 mg cm -2 Pt and cathode catalyst layer at 0.4 mg cm -2 of Pt and Ru. At the specified cell and humidification temperatures, the thin PRIMEA 57 membrane yields better cell performance than the thick PRIMEA 5621 membrane, since hydration of the former is more easily maintained with the limited amount of produced water. Sufficient humidification at both the cathode and anode sides is essential to achieve high cell performance with a thick membrane, like the PRIMEA 5621. The optimal cell temperature to produce the best cell performance with PRIMEA 5621 is close to the humidification temperature. For PRIMEA 57, however, optimal cell temperature exceeds the humidification temperature.

  12. CD28 controls the development of innate-like CD8+ T cells by promoting the functional maturation of NKT cells.

    Science.gov (United States)

    Yousefi, Mitra; Duplay, Pascale

    2013-11-01

    NK T cells(NKT cells) share functional characteristics and homing properties that are distinct from conventional T cells. In this study, we investigated the contribution of CD28 in the functional development of γδ NKT and αβ NKT cells in mice. We show that CD28 promotes the thymic maturation of promyelocytic leukemia zinc finger(+) IL-4(+) NKT cells and upregulation of LFA-1 expression on NKT cells. We demonstrate that the developmental defect of γδ NKT cells in CD28-deficient mice is cell autonomous. Moreover, we show in both wild-type C57BL/6 mice and in downstream of tyrosine kinase-1 transgenic mice, a mouse model with increased numbers of γδ NKT cells, that CD28-mediated regulation of thymic IL-4(+) NKT cells promotes the differentiation of eomesodermin(+) CD44(high) innate-like CD8(+) T cells. These findings reveal a previously unappreciated mechanism by which CD28 controls NKT-cell homeostasis and the size of the innate-like CD8(+) T-cell pool. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Controlling Factors of Cell Design on Large-Format Li-Ion Battery Safety during Nail Penetration

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qing; Shaffer, Christian Edward, E-mail: ceshaffer@ecpowergroup.com; Sinha, Puneet K. [EC Power, State College, PA (United States)

    2015-08-21

    In this paper, we investigate the controlling design parameters of large-format Li-ion batteries on safety while undergoing nail penetration. We have identified three critical design parameters that control the safety during the nail penetration process: nail diameter (D{sub nail}), single sheet foil area (A{sub foil}), and cell capacity (Q{sub cell}).Using commercial AutoLion™ software, we have investigated two typical design problems related to the selection of cell thickness and aspect ratio, namely, (1) the safety ramifications of increasing cell capacity via greater cell thickness for a fixed footprint and (2) the effect of aspect ratio, or single sheet foil size, on safety at a given capacity. For a fixed footprint, our results indicate that the safety of the cell can be predicted by (Q{sub cell} D{sub nail}{sup -0.5}). For a given cell capacity, our results indicate that typically a larger single sheet foil area leads to a greater likelihood for thermal runaway due to its effect of making the heating more local in nature; however, for small cells (~5 Ah) and large nails (~20 mm), the greater aspect ratio can lead to a safer cell, as the greater surface area strongly cools the global heating of the cell.

  14. Comparative effects of macro-sized aluminum oxide and aluminum oxide nanoparticles on erythrocyte hemolysis: influence of cell source, temperature, and size

    Energy Technology Data Exchange (ETDEWEB)

    Vinardell, M. P., E-mail: mpvinardellmh@ub.edu; Sordé, A. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain); Díaz, J. [Universitat de Barcelona CCiT, Scientific and Technological Centers (Spain); Baccarin, T.; Mitjans, M. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain)

    2015-02-15

    Al{sub 2}O{sub 3} is the most abundantly produced nanomaterial and has been used in diverse fields, including the medical, military, and industrial sectors. As there are concerns about the health effects of nanoparticles, it is important to understand how they interact with cells, and specifically with red blood cells. The hemolysis induced by three commercial nano-sized aluminum oxide particles (nanopowder 13 nm, nanopowder <50 nm, and nanowire 2–6 × 200–400 nm) was compared to aluminum oxide and has been studied on erythrocytes from humans, rats, and rabbits, in order to elucidate the mechanism of action and the influence of size and shape on hemolytic behavior. The concentrations inducing 50 % hemolysis (HC{sub 50}) were calculated for each compound studied. The most hemolytic aluminum oxide particles were of nanopowder 13, followed by nanowire and nanopowder 50. The addition of albumin to PBS induced a protective effect on hemolysis in all the nano-forms of Al{sub 2}O{sub 3}, but not on Al{sub 2}O{sub 3}. The drop in HC{sub 50} correlated to a decrease in nanomaterial size, which was induced by a reduction of aggregation. Aluminum oxide nanoparticles are less hemolytic than other oxide nanoparticles and behave differently depending on the size and shape of the nanoparticles. The hemolytic behavior of aluminum oxide nanoparticles differs from that of aluminum oxide.

  15. Asymmetric cell division during T cell development controls downstream fate

    Science.gov (United States)

    Pham, Kim; Shimoni, Raz; Charnley, Mirren; Ludford-Menting, Mandy J.; Hawkins, Edwin D.; Ramsbottom, Kelly; Oliaro, Jane; Izon, David; Ting, Stephen B.; Reynolds, Joseph; Lythe, Grant; Molina-Paris, Carmen; Melichar, Heather; Robey, Ellen; Humbert, Patrick O.; Gu, Min

    2015-01-01

    During mammalian T cell development, the requirement for expansion of many individual T cell clones, rather than merely expansion of the entire T cell population, suggests a possible role for asymmetric cell division (ACD). We show that ACD of developing T cells controls cell fate through differential inheritance of cell fate determinants Numb and α-Adaptin. ACD occurs specifically during the β-selection stage of T cell development, and subsequent divisions are predominantly symmetric. ACD is controlled by interaction with stromal cells and chemokine receptor signaling and uses a conserved network of polarity regulators. The disruption of polarity by deletion of the polarity regulator, Scribble, or the altered inheritance of fate determinants impacts subsequent fate decisions to influence the numbers of DN4 cells arising after the β-selection checkpoint. These findings indicate that ACD enables the thymic microenvironment to orchestrate fate decisions related to differentiation and self-renewal. PMID:26370500

  16. Fuel cell with internal flow control

    Science.gov (United States)

    Haltiner, Jr., Karl J.; Venkiteswaran, Arun [Karnataka, IN

    2012-06-12

    A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

  17. Exact, time-independent estimation of clone size distributions in normal and mutated cells.

    Science.gov (United States)

    Roshan, A; Jones, P H; Greenman, C D

    2014-10-06

    Biological tools such as genetic lineage tracing, three-dimensional confocal microscopy and next-generation DNA sequencing are providing new ways to quantify the distribution of clones of normal and mutated cells. Understanding population-wide clone size distributions in vivo is complicated by multiple cell types within observed tissues, and overlapping birth and death processes. This has led to the increased need for mathematically informed models to understand their biological significance. Standard approaches usually require knowledge of clonal age. We show that modelling on clone size independent of time is an alternative method that offers certain analytical advantages; it can help parametrize these models, and obtain distributions for counts of mutated or proliferating cells, for example. When applied to a general birth-death process common in epithelial progenitors, this takes the form of a gambler's ruin problem, the solution of which relates to counting Motzkin lattice paths. Applying this approach to mutational processes, alternative, exact, formulations of classic Luria-Delbrück-type problems emerge. This approach can be extended beyond neutral models of mutant clonal evolution. Applications of these approaches are twofold. First, we resolve the probability of progenitor cells generating proliferating or differentiating progeny in clonal lineage tracing experiments in vivo or cell culture assays where clone age is not known. Second, we model mutation frequency distributions that deep sequencing of subclonal samples produce.

  18. Effect of hydroxyapatite particle size, morphology and crystallinity on proliferation of colon cancer HCT116 cells

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Sangeeta; Das, Mitun, E-mail: mitun@cgcri.res.in; Balla, Vamsi Krishna

    2014-06-01

    The aim of the present work is to chemically and physically characterize the synthesized Hydroxyapatite (HAp) micro and nanoparticles and to explore the inhibitory effect of nano-HAps on the in vitro growth of human colon cancerous cells HCT116. HAp powder was synthesized using three different routes to achieve micro and nanosized powders, with different morphologies and crystallinity. The synthesized powders were characterized using X-ray diffraction, FTIR spectroscopy and scanning electron microscope. The results showed that the average crystallite size of HAp powder varies from 11 nm to 177 nm and respective crystallinity of powder found to be in the range of 0.12 and 0.92. The effect of these physico-chemical properties of HAp powders on human colon cancer HCT116 cells inhibition was determined in vitro. It was found that decreasing the HAp powder crystallite size between 11 nm and 22 nm significantly increases the HCT116 cell inhibition. Our results demonstrate that apart from HAp powder size their crystallinity and morphology also play an important role in cellular inhibition of human colon cancer cells. - Highlights: • Chemically synthesized hydroxyapatite micro and nano-particles with different morphologies and crystallinity. • In vitro cell–material interaction showed that hydroxyapatite nano-particles inhibit colon cancer cells. • Human colon cancer cell inhibition also depends on crystallinity and morphology of HAp powder.

  19. Manipulation of signaling thresholds in "engineered stem cell niches" identifies design criteria for pluripotent stem cell screens.

    Directory of Open Access Journals (Sweden)

    Raheem Peerani

    Full Text Available In vivo, stem cell fate is regulated by local microenvironmental parameters. Governing parameters in this stem cell niche include soluble factors, extra-cellular matrix, and cell-cell interactions. The complexity of this in vivo niche limits analyses into how individual niche parameters regulate stem cell fate. Herein we use mouse embryonic stem cells (mESC and micro-contact printing (microCP to investigate how niche size controls endogenous signaling thresholds. microCP is used to restrict colony diameter, separation, and degree of clustering. We show, for the first time, spatial control over the activation of the Janus kinase/signal transducer and activator of transcription pathway (Jak-Stat. The functional consequences of this niche-size-dependent signaling control are confirmed by demonstrating that direct and indirect transcriptional targets of Stat3, including members of the Jak-Stat pathway and pluripotency-associated genes, are regulated by colony size. Modeling results and empirical observations demonstrate that colonies less than 100 microm in diameter are too small to maximize endogenous Stat3 activation and that colonies separated by more than 400 microm can be considered independent from each other. These results define parameter boundaries for the use of ESCs in screening studies, demonstrate the importance of context in stem cell responsiveness to exogenous cues, and suggest that niche size is an important parameter in stem cell fate control.

  20. Surfactant effects in magnetite nanoparticles of controlled size

    International Nuclear Information System (INIS)

    Guardia, P.; Batlle-Brugal, B.; Roca, A.G.; Iglesias, O.; Morales, M.P.; Serna, C.J.; Labarta, A.; Batlle, X.

    2007-01-01

    Magnetite Fe 3 O 4 nanoparticles of controlled size within 6 and 20 nm in diameter were synthesised by thermal decomposition of an iron organic precursor in an organic medium. Particles were coated with oleic acid. For all samples studied, saturation magnetisation M s is size-independent, and reaches a value close to that expected for bulk magnetite, in contrast to results in small particle systems for which M s is usually much smaller due to surface spin disorder. The coercive field for the 6 nm particles is in agreement with coherent rotation, taking the bulk magnetocrystalline anisotropy into account. Both results suggest that the oleic acid molecules covalently bonded to the nanoparticle surface yield a strong reduction in the surface spin disorder. However, although the saturated state may be similar, the approach to saturation is different and, in particular, the high-field differential susceptibility is one order of magnitude larger than in bulk materials. The relevance of these results in biomedical applications is discussed

  1. Assessing T cell clonal size distribution: a non-parametric approach.

    Directory of Open Access Journals (Sweden)

    Olesya V Bolkhovskaya

    Full Text Available Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity.

  2. Nanometer-scale sizing accuracy of particle suspensions on an unmodified cell phone using elastic light scattering.

    Directory of Open Access Journals (Sweden)

    Zachary J Smith

    Full Text Available We report on the construction of a Fourier plane imaging system attached to a cell phone. By illuminating particle suspensions with a collimated beam from an inexpensive diode laser, angularly resolved scattering patterns are imaged by the phone's camera. Analyzing these patterns with Mie theory results in predictions of size distributions of the particles in suspension. Despite using consumer grade electronics, we extracted size distributions of sphere suspensions with better than 20 nm accuracy in determining the mean size. We also show results from milk, yeast, and blood cells. Performing these measurements on a portable device presents opportunities for field-testing of food quality, process monitoring, and medical diagnosis.

  3. Sliding-Mode Control of PEM Fuel Cells

    CERN Document Server

    Kunusch, Cristian; Mayosky, Miguel

    2012-01-01

    Recent advances in catalysis technologies and new materials make fuel cells an economically appealing and clean energy source with massive market potential in portable devices, home power generation and the automotive industry. Among the more promising fuel-cell technologies are proton exchange membrane fuel cells (PEMFCs). Sliding-Mode Control of PEM Fuel Cells demonstrates the application of higher-order sliding-mode control to PEMFC dynamics. Fuel-cell dynamics are often highly nonlinear and the text shows the advantages of sliding modes in terms of robustness to external disturbance, modelling error and system-parametric disturbance using higher-order control to reduce chattering. Divided into two parts, the book first introduces the theory of fuel cells and sliding-mode control. It begins by contextualising PEMFCs both in terms of their development and within the hydrogen economy and today’s energy production situation as a whole. The reader is then guided through a discussion of fuel-cell operation pr...

  4. Some regularity of the grain size distribution in nuclear fuel with controllable structure

    International Nuclear Information System (INIS)

    Loktev, Igor

    2008-01-01

    It is known, the fission gas release from ceramic nuclear fuel depends from average size of grains. To increase grain size they use additives which activate sintering of pellets. However, grain size distribution influences on fission gas release also. Fuel with different structures, but with the same average size of grains has different fission gas release. Other structure elements, which influence operational behavior of fuel, are pores and inclusions. Earlier, in Kyoto, questions of distribution of grain size for fuel with 'natural' structure were discussed. Some regularity of grain size distribution of fuel with controllable structure and high average size of grains are considered in the report. Influence of inclusions and pores on an error of the automated definition of parameters of structure is shown. The criterion, which describe of behavior of fuel with specific grain size distribution, is offered

  5. Outside-in control -Does plant cell wall integrity regulate cell cycle progression?

    Science.gov (United States)

    Gigli-Bisceglia, Nora; Hamann, Thorsten

    2018-04-13

    During recent years it has become accepted that plant cell walls are not inert objects surrounding all plant cells but are instead highly dynamic, plastic structures. They are involved in a large number of cell biological processes and contribute actively to plant growth, development and interaction with environment. Therefore, it is not surprising that cellular processes can control plant cell wall integrity while, simultaneously, cell wall integrity can influence cellular processes. In yeast and animal cells such a bi-directional relationship also exists between the yeast/animal extra-cellular matrices and the cell cycle. In yeast, the cell wall integrity maintenance mechanism and a dedicated plasmamembrane integrity checkpoint are mediating this relationship. Recent research has yielded insights into the mechanism controlling plant cell wall metabolism during cytokinesis. However, knowledge regarding putative regulatory pathways controlling adaptive modifications in plant cell cycle activity in response to changes in the state of the plant cell wall are not yet identified. In this review, we summarize similarities and differences in regulatory mechanisms coordinating extra cellular matrices and cell cycle activity in animal and yeast cells, discuss the available evidence supporting the existence of such a mechanism in plants and suggest that the plant cell wall integrity maintenance mechanism might also control cell cycle activity in plant cells. This article is protected by copyright. All rights reserved.

  6. How much territory can a single E. coli cell control?

    Directory of Open Access Journals (Sweden)

    Ziad W. El-Hajj

    2015-04-01

    Full Text Available Bacteria have been traditionally classified in terms of size and shape and are best known for their very small size. E. coli cells in particular are small rods, each 1-2 microns. However the size varies with the medium, and faster growing cells are larger because they must have more ribosomes to make more protoplasm per unit time, and ribosomes take up space. Indeed, Maaloe's experiments on how E. coli establishes its size began with shifts between rich and poor media.Recently much larger bacteria have been described, including Epulopiscium fishelsoni at 700 μm and Thiomargarita namibiensisis at 750 μm. These are not only much longer than E. coli cells but also much wider, necessitating considerable intracellular organization. Epulopiscium cells for instance, at 80 μm wide, enclose a large enough volume of cytoplasm to present it with major transport problems.This review surveys E. coli cells much longer than those which grow in nature and in usual lab cultures. These include cells mutated in a single gene (metK which are 2-4x longer than their nonmutated parent. This metK mutant stops dividing when slowly starved of S-adenosylmethionine but continues to elongate to 50 μm and more. FtsZ mutants have been routinely isolated as long cells which form during growth at 42°C. The SOS response is a well-characterized regulatory network that is activated in response to DNA damage and also results in cell elongation. Our champion elongated E. coli is a metK strain with a further, as yet unidentified mutation, which reaches 750 μm with no internal divisions and no increase in width.

  7. Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors

    Science.gov (United States)

    Sohrabi, Mehdi

    2017-11-01

    A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

  8. Electronic structure and size of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods

    CERN Document Server

    Soriano, L; Sanchez-Agudo, M; Sanz, J M; Ahonen, P P; Kauppinen, E I; Palomares, F J; Bressler, P R

    2002-01-01

    A complete characterization of nanostructures has to deal both with electronic structure and dimensions. Here we present the characterization of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods. The electronic structure of these nanoparticles was probed by x-ray absorption spectroscopy (XAS), the particle size by atomic force microscopy (AFM). XAS spectra show that the particles crystallize in the anatase phase upon heating at 500 sup o C, whereas further annealing at 700 sup o C give crystallites of 70 % anatase and 30 % rutile phases. Raising the temperature to 900 sup o C results in a complete transformation of the particles to rutile. AFM images reveal that the mean size of the anatase particles formed upon heating at 500 sup o C is 30 nm, whereas for the rutile particles formed upon annealing at 900 sup o C 90 nm were found. The results obtained by these techniques agree with XRD data. (author)

  9. Nanocluster production for solar cell applications

    International Nuclear Information System (INIS)

    Al Dosari, Haila M.; Ayesh, Ahmad I.

    2013-01-01

    This research focuses on the fabrication and characterization of silver (Ag) and silicon (Si) nanoclusters that might be used for solar cell applications. Silver and silicon nanoclusters have been synthesized by means of dc magnetron sputtering and inert gas condensation inside an ultra-high vacuum compatible system. We have found that nanocluster size distributions can be tuned by various source parameters, such as the sputtering discharge power, flow rate of argon inert gas, and aggregation length. Quadrupole mass filter and transmission electron microscopy were used to evaluate the size distribution of Ag and Si nanoclusters. Ag nanoclusters with average size in the range of 3.6–8.3 nm were synthesized (herein size refers to the nanocluster diameter), whereas Si nanoclusters' average size was controlled to range between 2.9 and 7.4 nm by controlling the source parameters. This work illustrates the ability of controlling the Si and Ag nanoclusters' sizes by proper optimization of the operation conditions. By controlling nanoclusters' sizes, one can alter their surface properties to suit the need to enhance solar cell efficiency. Herein, Ag nanoclusters were deposited on commercial polycrystalline solar cells. Short circuit current (I SC ), open circuit voltage (V OC ), fill factor, and efficiency (η) were obtained under light source with an intensity of 30 mW/cm 2 . A 22.7% enhancement in solar cell efficiency could be measured after deposition of Ag nanoclusters, which demonstrates that Ag nanoclusters generated in this work are useful to enhance solar cell efficiency

  10. Hydrologic Controls on Shallow Landslide Location, Size, and Shape

    Science.gov (United States)

    Bellugi, D.; Milledge, D.; Perron, T.; McKean, J. A.; Dietrich, W.; Rulli, M.

    2012-12-01

    Shallow landslides, typically involving just the soil mantle, are principally controlled by topography, soil and root strengths, and soil thickness, and are typically triggered by storm-induced increases in pore water pressure. The response of a landscape to landslide-triggering storms will thus depend on factors such as rainfall totals, storm intensity and duration, and antecedent moisture conditions. The two dominant mechanisms that generate high pore water pressures at a point are topographically-steered lateral subsurface flow (over timescales of days to weeks), and rapid vertical infiltration (over timescales of minutes to hours). We aim to understand the impact of different storm characteristics and hydrologic regimes on shallow landslide location, size, and shape. We have developed a regional-scale model, which applies a low-parameter grid-based multi-dimensional slope stability model within a novel search algorithm, to generate discrete landslide predictions. This model shows that the spatial organization of parameters such as root strength and pore water pressure has a strong control on shallow landslide location, size, and shape. We apply this model to a field site near Coos Bay, OR, where a ten-year landslide inventory has been mapped onto high-resolution topographic data. Our model predicts landslide size generally increases with increasing rainfall intensity, except when root strength is extremely high and pore pressures are topographically steered. The distribution of topographic index values (the ratios of contributing area to slope) of predicted landslides is a clear signature of the pore water pressure generation mechanism: as laterally dominated flow increases, landslides develop in locations with lower slopes and higher contributing areas; in contrast, in the case of vertically-dominated pore pressure rise, landslides are consistently found in locations with higher slopes and lower contributing areas. While in both cases landslides are found in

  11. Cdc42-mediated tubulogenesis controls cell specification

    DEFF Research Database (Denmark)

    Kesavan, Gokul; Sand, Fredrik Wolfhagen; Greiner, Thomas Uwe

    2009-01-01

    Understanding how cells polarize and coordinate tubulogenesis during organ formation is a central question in biology. Tubulogenesis often coincides with cell-lineage specification during organ development. Hence, an elementary question is whether these two processes are independently controlled......, or whether proper cell specification depends on formation of tubes. To address these fundamental questions, we have studied the functional role of Cdc42 in pancreatic tubulogenesis. We present evidence that Cdc42 is essential for tube formation, specifically for initiating microlumen formation and later...... for maintaining apical cell polarity. Finally, we show that Cdc42 controls cell specification non-cell-autonomously by providing the correct microenvironment for proper control of cell-fate choices of multipotent progenitors. For a video summary of this article, see the PaperFlick file with the Supplemental Data...

  12. Lithium-Ion Cell Charge Control Unit

    Science.gov (United States)

    Reid, Concha; Button, Robert; Manzo, Michelle; McKissock, Barbara; Miller, Thomas; Gemeiner, Russel; Bennett, William; Hand, Evan

    2006-01-01

    Life-test data of Lithium-Ion battery cells is critical in order to establish their performance capabilities for NASA missions and Exploration goals. Lithium-ion cells have the potential to replace rechargeable alkaline cells in aerospace applications, but they require a more complex charging scheme than is typically required for alkaline cells. To address these requirements in our Lithium-Ion Cell Test Verification Program, a Lithium-Ion Cell Charge Control Unit was developed by NASA Glenn Research Center (GRC). This unit gives researchers the ability to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and results in a substantial reduction in test costs as compared to individual cell testing. The Naval Surface Warfare Center at Crane, Indiana developed a power reduction scheme that works in conjunction with the Lithium-Ion Cell Charge Control Unit. This scheme minimizes the power dissipation required by the circuitry to prolong circuit life and improve its reliability.

  13. A Modified Thermal Treatment Method for the Up-Scalable Synthesis of Size-Controlled Nanocrystalline Titania

    Directory of Open Access Journals (Sweden)

    Aysar Sabah Keiteb

    2016-10-01

    Full Text Available Considering the increasing demand for titania nanoparticles with controlled quality for various applications, the present work reports the up-scalable synthesis of size-controlled titanium dioxide nanocrystals with a simple and convenient thermal treatment route. Titanium dioxide nanocrystals with tetragonal structure were synthesized directly from an aqueous solution containing titanium (IV isopropoxide as the main reactant, polyvinyl pyrrolidone (PVP as the capping agent, and deionized water as a solvent. With the elimination of the drying process in a thermal treatment method, an attempt was made to decrease the synthesis time. The mixture directly underwent calcination to form titanium dioxide (TiO2 nanocrystalline powder, which was confirmed by FT-IR, energy dispersive X-ray spectroscopy (EDX, and X-ray diffraction (XRD analysis. The control over the size and optical properties of nanocrystals was achieved via variation in calcination temperatures. The obtained average sizes from XRD spectra and transmission electron microscopy (TEM images showed exponential variation with increasing calcination temperature. The optical properties showed a decrease in the band gap energy with increasing calcination temperature due to the enlargement of the nanoparticle size. These results prove that direct calcination of reactant solution is a convenient thermal treatment route for the potential large-scale production of size-controlled Titania nanoparticles.

  14. Engineering models and methods for industrial cell control

    DEFF Research Database (Denmark)

    Lynggaard, Hans Jørgen Birk; Alting, Leo

    1997-01-01

    This paper is concerned with the engineering, i.e. the designing and making, of industrial cell control systems. The focus is on automated robot welding cells in the shipbuilding industry. The industrial research project defines models and methods for design and implemen-tation of computer based...... SHIPYARD.It is concluded that cell control technology provides for increased performance in production systems, and that the Cell Control Engineering concept reduces the effort for providing and operating high quality and high functionality cell control solutions for the industry....... control and monitor-ing systems for production cells. The project participants are The Danish Academy of Technical Sciences, the Institute of Manufacturing Engineering at the Technical University of Denmark and ODENSE STEEL SHIPYARD Ltd.The manufacturing environment and the current practice...

  15. Size-dependent cytotoxicity of europium doped NaYF4 nanoparticles in endothelial cells

    International Nuclear Information System (INIS)

    Chen, Shizhu; Zhang, Cuimiao; Jia, Guang; Duan, Jianlei; Wang, Shuxiang; Zhang, Jinchao

    2014-01-01

    Lanthanide-doped sodium yttrium fluoride (NaYF 4 ) nanoparticles exhibit novel optical properties which make them be widely used in various fields. The extensive applications increase the chance of human exposure to these nanoparticles and thus raise deep concerns regarding their riskiness. In the present study, we have synthesized europium doped NaYF 4 (NaYF 4 :Eu 3+ ) nanoparticles with three diameters and used endothelial cells (ECs) as a cell model to explore the potential toxic effect. The cell viability, cytomembrane integrity, cellular uptake, intracellular localization, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), apoptosis detection, caspase-3 activity and expression of inflammatory gene were studied. The results indicated that these nanoparticles could be uptaken into ECs and decrease the cell viability, induce the intracellular lactate dehydrogenase (LDH) release, increase the ROS level, and decrease the cell MMP in a size-dependent manner. Besides that, the cells were suffered to apoptosis with the caspase-3 activation, and the inflammation specific gene expressions (ICAM1 and VCAM1) were also increased. Our results suggest that the damage pathway may be related to the ROS generation and mitochondrial damage. The results provide novel evidence to elucidate their toxicity mechanisms and may be helpful for more rational applications of these compounds in the future. - Highlights: • NaYF 4 :Eu 3+ nanoparticles with three diameters have been synthesized. • NaYF 4 :Eu 3+ nanoparticles could be uptaken by endothelial cells (ECs). • NaYF 4 :Eu 3+ nanoparticles show a significant cytotoxicity on ECs. • The size of NaYF 4 :Eu 3+ nanoparticles may be important to their toxicology effect

  16. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study.

    Science.gov (United States)

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-09-01

    Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. An opportunistic sample of 90 men from the community were recruited and divided into three groups: BDD (n = 26); SPA (n = 31) and controls (n = 33). The Index of Erectile Function (IEF), sexual identity and history; and interventions to alter the size of their penis. Men with BDD compared with controls had reduced erectile dysfunction, orgasmic function, intercourse satisfaction and overall satisfaction on the IEF. Men with SPA compared with controls had reduced intercourse satisfaction. There were no differences in sexual desire, the frequency of intercourse or masturbation across any of the three groups. Men with BDD and SPA were more likely than the controls to attempt to alter the shape or size of their penis (for example jelqing, vacuum pumps or stretching devices) with poor reported success. Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures.

  17. Comparison of cell homogenization methods considering interaction effect between fuel cells and control rod cells

    International Nuclear Information System (INIS)

    Takeda, T.; Uto, N.

    1988-01-01

    Several methods to determine cell-averaged group cross sections and anisotropic diffusion coefficients which consider the interaction effect between core fuel cells and control rods or control rod followers have been compared to discuss the physical meaning included in cell homogenization. As the cell homogenization methods considered are the commonly used flux-weighting method, the reaction rate preservation method and the reactivity preservation method. These homogenization methods have been applied to control rod worth calculations in 1-D slab cores to investigate their applicability. (author). 6 refs, 2 figs, 9 tabs

  18. The Role of Controlled Surface Topography and Chemistry on Mouse Embryonic Stem Cell Attachment, Growth and Self-Renewal.

    Science.gov (United States)

    Macgregor, Melanie; Williams, Rachel; Downes, Joni; Bachhuka, Akash; Vasilev, Krasimir

    2017-09-14

    The success of stem cell therapies relies heavily on our ability to control their fate in vitro during expansion to ensure an appropriate supply. The biophysical properties of the cell culture environment have been recognised as a potent stimuli influencing cellular behaviour. In this work we used advanced plasma-based techniques to generate model culture substrates with controlled nanotopographical features of 16 nm, 38 nm and 68 nm in magnitude, and three differently tailored surface chemical functionalities. The effect of these two surface properties on the adhesion, spreading, and self-renewal of mouse embryonic stem cells (mESCs) were assessed. The results demonstrated that physical and chemical cues influenced the behaviour of these stem cells in in vitro culture in different ways. The size of the nanotopographical features impacted on the cell adhesion, spreading and proliferation, while the chemistry influenced the cell self-renewal and differentiation.

  19. Cryo-electron microscopy and single molecule fluorescent microscopy detect CD4 receptor induced HIV size expansion prior to cell entry

    International Nuclear Information System (INIS)

    Pham, Son; Tabarin, Thibault; Garvey, Megan; Pade, Corinna; Rossy, Jérémie; Monaghan, Paul; Hyatt, Alex; Böcking, Till; Leis, Andrew; Gaus, Katharina; Mak, Johnson

    2015-01-01

    Viruses are often thought to have static structure, and they only remodel after the viruses have entered target cells. Here, we detected a size expansion of virus particles prior to viral entry using cryo-electron microscopy (cryo-EM) and single molecule fluorescence imaging. HIV expanded both under cell-free conditions with soluble receptor CD4 (sCD4) targeting the CD4 binding site on the HIV-1 envelope protein (Env) and when HIV binds to receptor on cellular membrane. We have shown that the HIV Env is needed to facilitate receptor induced virus size expansions, showing that the ‘lynchpin’ for size expansion is highly specific. We demonstrate that the size expansion required maturation of HIV and an internal capsid core with wild type stability, suggesting that different HIV compartments are linked and are involved in remodelling. Our work reveals a previously unknown event in HIV entry, and we propose that this pre-entry priming process enables HIV particles to facilitate the subsequent steps in infection. - Highlights: • Cell free viruses are able to receive external trigger that leads to apparent size expansion. • Virus envelope and CD4 receptor engagement is the lynchpin of virus size expansion. • Internal capsid organisation can influence receptor mediated virus size expansion. • Pre-existing virus-associated lipid membrane in cell free virus can accommodate the receptor mediated virus size expansion.

  20. Cryo-electron microscopy and single molecule fluorescent microscopy detect CD4 receptor induced HIV size expansion prior to cell entry

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Son [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Tabarin, Thibault [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Garvey, Megan; Pade, Corinna [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Rossy, Jérémie [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Monaghan, Paul; Hyatt, Alex [CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Böcking, Till [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Leis, Andrew [CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia); Gaus, Katharina, E-mail: k.gaus@unsw.edu.au [ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, New South Wales 3220 (Australia); Mak, Johnson, E-mail: j.mak@deakin.edu.au [Deakin University, Victoria 3216 (Australia); CSIRO Australian Animal Health Laboratory, Victoria 3220 (Australia)

    2015-12-15

    Viruses are often thought to have static structure, and they only remodel after the viruses have entered target cells. Here, we detected a size expansion of virus particles prior to viral entry using cryo-electron microscopy (cryo-EM) and single molecule fluorescence imaging. HIV expanded both under cell-free conditions with soluble receptor CD4 (sCD4) targeting the CD4 binding site on the HIV-1 envelope protein (Env) and when HIV binds to receptor on cellular membrane. We have shown that the HIV Env is needed to facilitate receptor induced virus size expansions, showing that the ‘lynchpin’ for size expansion is highly specific. We demonstrate that the size expansion required maturation of HIV and an internal capsid core with wild type stability, suggesting that different HIV compartments are linked and are involved in remodelling. Our work reveals a previously unknown event in HIV entry, and we propose that this pre-entry priming process enables HIV particles to facilitate the subsequent steps in infection. - Highlights: • Cell free viruses are able to receive external trigger that leads to apparent size expansion. • Virus envelope and CD4 receptor engagement is the lynchpin of virus size expansion. • Internal capsid organisation can influence receptor mediated virus size expansion. • Pre-existing virus-associated lipid membrane in cell free virus can accommodate the receptor mediated virus size expansion.

  1. On the Relationship between Pollen Size and Genome Size

    Directory of Open Access Journals (Sweden)

    Charles A. Knight

    2010-01-01

    Full Text Available Here we test whether genome size is a predictor of pollen size. If it were, inferences of ancient genome size would be possible using the abundant paleo-palynolgical record. We performed regression analyses across 464 species of pollen width and genome size. We found a significant positive trend. However, regression analysis using phylogentically independent contrasts did not support the correlated evolution of these traits. Instead, a large split between angiosperms and gymnosperms for both pollen width and genome size was revealed. Sister taxa were not more likely to show a positive contrast when compared to deeper nodes. However, significantly more congeneric species had a positive trend than expected by chance. These results may reflect the strong selection pressure for pollen to be small. Also, because pollen grains are not metabolically active when measured, their biology is different than other cells which have been shown to be strongly related to genome size, such as guard cells. Our findings contrast with previously published research. It was our hope that pollen size could be used as a proxy for inferring the genome size of ancient species. However, our results suggest pollen is not a good candidate for such endeavors.

  2. Particle size dependence of CO tolerance of anode PtRu catalysts for polymer electrolyte fuel cells

    Science.gov (United States)

    Yamanaka, Toshiro; Takeguchi, Tatsuya; Wang, Guoxiong; Muhamad, Ernee Noryana; Ueda, Wataru

    An anode catalyst for a polymer electrolyte fuel cell must be CO-tolerant, that is, it must have the function of hydrogen oxidation in the presence of CO, because hydrogen fuel gas generated by the steam reforming process of natural gas contains a small amount of CO. In the present study, PtRu/C catalysts were prepared with control of the degree of Pt-Ru alloying and the size of PtRu particles. This control has become possible by a new method of heat treatment at the final step in the preparation of catalysts. The CO tolerances of PtRu/C catalysts with the same degree of Pt-Ru alloying and with different average sizes of PtRu particles were thus compared. Polarization curves were obtained with pure H 2 and CO/H 2 (CO concentrations of 500-2040 ppm). It was found that the CO tolerance of highly dispersed PtRu/C (high dispersion (HD)) with small PtRu particles was much higher than that of poorly dispersed PtRu/C (low dispersion (LD)) with large metal particles. The CO tolerance of PtRu/C (HD) was higher than that of any commercial PtRu/C. The high CO tolerance of PtRu/C (HD) is thought to be due to efficient concerted functions of Pt, Ru, and their alloy.

  3. Size-controlled fluorescent nanodiamonds: A facile method of fabrication and color-center counting

    KAUST Repository

    Mahfouz, Remi; Floyd, Daniel L.; Peng, Wei; Choy, Jennifer; Lončar, Marko; Bakr, Osman

    2013-01-01

    findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color

  4. Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate.

    Science.gov (United States)

    Li, Feng; Chen, Yan; Liu, Shubo; Qi, Jian; Wang, Weiying; Wang, Chenhua; Zhong, Ruiyue; Chen, Zhijun; Li, Xiaoming; Guan, Yuanzhou; Kong, Wei; Zhang, Yong

    2017-01-01

    Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC) on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed.

  5. Controlling the microstructure and properties of titania nanopowders for high efficiency dye sensitized solar cells

    International Nuclear Information System (INIS)

    Shalan, A.E.; Rashad, M.M.; Yu, Youhai; Lira-Cantú, Mónica; Abdel-Mottaleb, M.S.A.

    2013-01-01

    Graphical abstract: (a) A highly ordered, vertically oriented TiO 2 nanorods compared with TiO 2 nanopaticles and (b) Dye sensitized solar cell fabricated using sealing technique. Highlights: ► TiO 2 nanorods particles size of 3–5 nm was synthesized hydrothermally at 100 °C. ► S BET was 78.14 m 2 /g and the band gap energy was 3.2 eV. ► (J sc ) and (V oc ) of the DSSC were in the range 10.84–13.23 mA cm −2 and 0.71–0.78 V. ► Conversion efficiency of DSSCs was 7.2%. ► IPCE analyses of the DSSC showed two peaks, at ∼350 and 520 nm. -- Abstract: A low temperature hydrothermal process have been developed to synthesize titania nanorods (NRs) and nanoparticles (NPs) with controlled size for dye sensitized solar cells (DSSCs). Effect of calcination temperature on the performance of TiO 2 nanoparticles for solar cells was investigated and discussed. The crystallite size and the relative crystallinity of the anatase phase were increased with increasing the calcination temperature. The structures and morphologies of both (TiO 2 nanorods and nanoparticles) were characterized using XRD, SEM, TEM/HRTEM, UV–vis Spectroscopy, FTIR and BET specific surface area (S BET ) as well as pore-size distribution by BJH. The size of the titania nanorods was 6.7 nm width and 22 nm length while it was 13 nm for nanoparticles. Efficiency of dye-sensitized solar cells (DSSCs) fabricated with oriented TiO 2 nanorods was reported to be more superior compared to DSSC based on mesoporous TiO 2 nanoparticles due to their high surface area, hierarchically mesoporous structures, low charge recombination and fast electron-transfer rate. With increasing calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) decreased. The efficiency of the assembly solar cells was decreased due to the agglomeration of the particles and difficulty of electron movement. The power efficiency was enhanced from 1.7% for TiO 2 nanoparticles cells at

  6. Control points within the cell cycle

    International Nuclear Information System (INIS)

    Van't Hof, J.

    1984-01-01

    Evidence of the temporal order of chromosomal DNA replication argues favorably for the view that the cell cycle is controlled by genes acting in sequence whose time of expression is determined by mitosis and the amount of nuclear DNA (2C vs 4C) in the cell. Gl and G2 appear to be carbohydrate dependent in that cells starved of either carbohydrate of phosphate fail to make these transitions. Cells deprived of nitrate, however, fail only at Gl to S transition indicating that the controls that operate in G1 differ from those that operate in G2. 46 references, 5 figures

  7. Factors controlling the population size of microbes in groundwater from AECL's Underground Research Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Stroes-Gascoyne, S.; Hamon, C. [Atomic Energy of Canada Limited, Whiteshell Labs., Pinawa, Manitoba (Canada); Mills, K. [University of Saskatoon, Saskatoon, SK (Canada); Rana, S.; Vaidyanathan, S. [Deep River Science Academy, Whiteshell Campus Summer 1997, Pinawa, Manitoba (Canada)

    2001-01-01

    Microbial populations in groundwaters from AECL's Underground Research Laboratory (URL) range from 10{sup 3} to 10{sup 5} cells/mL. Based on the total dissolved organic carbon (DOC), nitrate and phosphate content of these waters, populations of about 10{sup 5} to 10{sup 7} cells/mL should be possible. Upon storage of groundwater samples, total cell counts generally increase and viable cell counts always increase. A study was undertaken to determine what controls the in situ microbial population size in groundwater and what causes this population to grow upon sampling. Fresh URL groundwater was filter-sterilized, inoculated with small quantities of the unaltered water and incubated in the absence and presence of added nutrients (nitrate, phosphate and glucose). Unfiltered groundwater and R2A growth medium inoculated with unaltered groundwater, were also incubated. Microbial changes over time were followed by total and viable (on R2A medium) cell counts. Results showed that in the absence of any nutrient addition, populations grew to between 5 x 10{sup 5} to 4 x 10{sup 6} cells/mL, regardless of the initial size of the population ({approx}10{sup 1} to 10{sup 4} cells/mL), suggesting that nutrients for growth were available in the unamended groundwater. It was hypothesized that the original groundwater population was in 'equilibrium' with the underground environment, which likely included a large population of sessile cells in biofilms on fracture surfaces. Sampling of the groundwater removed the large demand on nutrient supplies by the sessile population which subsequently allowed the planktonic population to grow to a new 'equilibrium' with the available nutrients in the sample bottles. Addition of single nutrients (C, N or P) did not increase cell numbers, suggesting that more than one nutrient is limiting growth. Glucose was used very efficiently aerobically in the presence of both added N and P, but somewhat less under anaerobic

  8. Computer control of shielded cell operations

    International Nuclear Information System (INIS)

    Jeffords, W.R. III.

    1987-01-01

    This paper describes in detail a computer system to remotely control shielded cell operations. System hardware, software, and design criteria are discussed. We have designed a computer-controlled buret that provides a tenfold improvement over the buret currently in service. A computer also automatically controls cell analyses, calibrations, and maintenance. This system improves conditions for the operators by providing a safer, more efficient working environment and is expandable for future growth and development

  9. Colloidal Synthesis of Quantum Confined Single Crystal CsPbBr3 Nanosheets with Lateral Size Control up to the Micrometer Range.

    Science.gov (United States)

    Shamsi, Javad; Dang, Zhiya; Bianchini, Paolo; Canale, Claudio; Stasio, Francesco Di; Brescia, Rosaria; Prato, Mirko; Manna, Liberato

    2016-06-15

    We report the nontemplated colloidal synthesis of single crystal CsPbBr3 perovskite nanosheets with lateral sizes up to a few micrometers and with thickness of just a few unit cells (i.e., below 5 nm), hence in the strong quantum confinement regime, by introducing short ligands (octanoic acid and octylamine) in the synthesis together with longer ones (oleic acid and oleylamine). The lateral size is tunable by varying the ratio of shorter ligands over longer ligands, while the thickness is mainly unaffected by this parameter and stays practically constant at 3 nm in all the syntheses conducted at short-to-long ligands volumetric ratio below 0.67. Beyond this ratio, control over the thickness is lost and a multimodal thickness distribution is observed.

  10. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    Science.gov (United States)

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-01-01

    Introduction Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. Aim To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. Methods An opportunistic sample of 90 men from the community were recruited and divided into three groups: BDD (n = 26); SPA (n = 31) and controls (n = 33). Main Outcome Measures The Index of Erectile Function (IEF), sexual identity and history; and interventions to alter the size of their penis. Results Men with BDD compared with controls had reduced erectile dysfunction, orgasmic function, intercourse satisfaction and overall satisfaction on the IEF. Men with SPA compared with controls had reduced intercourse satisfaction. There were no differences in sexual desire, the frequency of intercourse or masturbation across any of the three groups. Men with BDD and SPA were more likely than the controls to attempt to alter the shape or size of their penis (for example jelqing, vacuum pumps or stretching devices) with poor reported success. Conclusion Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures. PMID:26468378

  11. Nonthermal plasma synthesis of size-controlled, monodisperse, freestanding germanium nanocrystals

    International Nuclear Information System (INIS)

    Gresback, Ryan; Holman, Zachary; Kortshagen, Uwe

    2007-01-01

    Germanium nanocrystals may be of interest for a variety of electronic and optoelectronic applications including photovoltaics, primarily due to the tunability of their band gap from the infrared into the visible range of the spectrum. This letter discusses the synthesis of monodisperse germanium nanocrystals via a nonthermal plasma approach which allows for precise control of the nanocrystal size. Germanium crystals are synthesized from germanium tetrachloride and hydrogen entrained in an argon background gas. The crystal size can be varied between 4 and 50 nm by changing the residence times of crystals in the plasma between ∼30 and 440 ms. Adjusting the plasma power enables one to synthesize fully amorphous or fully crystalline particles with otherwise similar properties

  12. Micro-/Nano- sized hydroxyapatite directs differentiation of rat bone marrow derived mesenchymal stem cells towards an osteoblast lineage

    Science.gov (United States)

    Huang, Yan; Zhou, Gang; Zheng, Lisha; Liu, Haifeng; Niu, Xufeng; Fan, Yubo

    2012-03-01

    Regenerative medicine consisting of cells and materials provides a new way for the repair and regeneration of tissues and organs. Nano-biomaterials are highlighted due to their advantageous features compared with conventional micro-materials. The aim of this study is to investigate the effects of micro-/nano- sized hydroxyapatite (μ/n-HA) on the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells (rBMSCs). μ/n-HA were prepared by a microwave synthesizer and precipitation method, respectively. Different sizes of μ/n-HA were characterized by IR, XRD, SEM, TEM and co-cultured with rBMSCs. It was shown that rBMSCs expressed higher levels of osteoblast-related markers by n-HA than μ-HA stimulation. The size of HA is an important factor for affecting the osteogenic differentiation of rBMSCs. This provides a new avenue for mechanistic studies of stem cell differentiation and a new approach to obtain more committed differentiated cells.

  13. Aerosol feed direct methanol fuel cell

    Science.gov (United States)

    Kindler, Andrew (Inventor); Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2002-01-01

    Improvements to fuel cells include introduction of the fuel as an aerosol of liquid fuel droplets suspended in a gas. The particle size of the liquid fuel droplets may be controlled for optimal fuel cell performance by selection of different aerosol generators or by separating droplets based upon size using a particle size conditioner.

  14. Effect of heterogeneity on the characterization of cell membrane compartments: I. Uniform size and permeability.

    Science.gov (United States)

    Hall, Damien

    2010-03-15

    Observations of the motion of individual molecules in the membrane of a number of different cell types have led to the suggestion that the outer membrane of many eukaryotic cells may be effectively partitioned into microdomains. A major cause of this suggested partitioning is believed to be due to the direct/indirect association of the cytosolic face of the cell membrane with the cortical cytoskeleton. Such intimate association is thought to introduce effective hydrodynamic barriers into the membrane that are capable of frustrating molecular Brownian motion over distance scales greater than the average size of the compartment. To date, the standard analytical method for deducing compartment characteristics has relied on observing the random walk behavior of a labeled lipid or protein at various temporal frequencies and different total lengths of time. Simple theoretical arguments suggest that the presence of restrictive barriers imparts a characteristic turnover to a plot of mean squared displacement versus sampling period that can be interpreted to yield the average dimensions of the compartment expressed as the respective side lengths of a rectangle. In the following series of articles, we used computer simulation methods to investigate how well the conventional analytical strategy coped with heterogeneity in size, shape, and barrier permeability of the cell membrane compartments. We also explored questions relating to the necessary extent of sampling required (with regard to both the recorded time of a single trajectory and the number of trajectories included in the measurement bin) for faithful representation of the actual distribution of compartment sizes found using the SPT technique. In the current investigation, we turned our attention to the analytical characterization of diffusion through cell membrane compartments having both a uniform size and permeability. For this ideal case, we found that (i) an optimum sampling time interval existed for the analysis

  15. Fabrication of corneal epithelial cell sheets maintaining colony-forming cells without feeder cells by oxygen-controlled method.

    Science.gov (United States)

    Nakajima, Ryota; Takeda, Shizu

    2014-01-01

    The use of murine 3T3 feeder cells needs to be avoided when fabricating corneal epithelial cell sheets for use in treating ocular surface diseases. However, the expression level of the epithelial stem/progenitor cell marker, p63, is down-regulated in feeder-free culture systems. In this study, in order to fabricate corneal epithelial cell sheets that maintain colony-forming cells without using any feeder cells, we investigated the use of an oxygen-controlled method that was developed previously to fabricate cell sheets efficiently. Rabbit limbal epithelial cells were cultured under hypoxia (1-10% O2) and under normoxia during stratification after reaching confluence. Multilayered corneal epithelial cell sheets were fabricated using an oxygen-controlled method, and immunofluorescence analysis showed that cytokeratin 3 and p63 was expressed in appropriate localization in the cell sheets. The colony-forming efficiency of the cell sheets fabricated by the oxygen-controlled method without feeder cells was significantly higher than that of cell sheets fabricated under 20% O2 without feeder cells. These results indicate that the oxygen-controlled method has the potential to achieve a feeder-free culture system for fabricating corneal epithelial cell sheets for corneal regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Size and morphology effects of titania on dye-sensitized solar cells performance

    International Nuclear Information System (INIS)

    Chien, Wen-Chen; Lin, Chien-Chih; Jang, Shiue-Ming; Kao, Tien-Hsieh

    2013-01-01

    This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m 2 /g for P25, 48.3 m 2 /g for SP25, 42.6 m 2 /g for NWs, and 40.3 m 2 /g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm 2 (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced

  17. Size and morphology effects of titania on dye-sensitized solar cells performance

    Energy Technology Data Exchange (ETDEWEB)

    Chien, Wen-Chen, E-mail: wcchien@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Lin, Chien-Chih [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Jang, Shiue-Ming [Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Kao, Tien-Hsieh [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China)

    2013-10-01

    This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m{sup 2}/g for P25, 48.3 m{sup 2}/g for SP25, 42.6 m{sup 2}/g for NWs, and 40.3 m{sup 2}/g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm{sup 2} (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced.

  18. The Organization of Nanoporous Structure Using Controlled Micelle Size from MPEG-b-PDLLA Block Copolymers

    International Nuclear Information System (INIS)

    Chang, Jeong Ho; Kim, Kyung Ja; Shin, Young Kook

    2004-01-01

    Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 A with the increase of hydrophobic chain lengths and up to 660 m 2 /g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state 13 C and 29 Si NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates

  19. Genetic algorithm with small population size for search feasible control parameters for parallel hybrid electric vehicles

    Directory of Open Access Journals (Sweden)

    Yu-Huei Cheng

    2017-11-01

    Full Text Available The control strategy is a major unit in hybrid electric vehicles (HEVs. In order to provide suitable control parameters for reducing fuel consumptions and engine emissions while maintaining vehicle performance requirements, the genetic algorithm (GA with small population size is applied to search for feasible control parameters in parallel HEVs. The electric assist control strategy (EACS is used as the fundamental control strategy of parallel HEVs. The dynamic performance requirements stipulated in the Partnership for a New Generation of Vehicles (PNGV is considered to maintain the vehicle performance. The known ADvanced VehIcle SimulatOR (ADVISOR is used to simulate a specific parallel HEV with urban dynamometer driving schedule (UDDS. Five population sets with size 5, 10, 15, 20, and 25 are used in the GA. The experimental results show that the GA with population size of 25 is the best for selecting feasible control parameters in parallel HEVs.

  20. Redundant control of migration and adhesion by ERM proteins in vascular smooth muscle cells

    International Nuclear Information System (INIS)

    Baeyens, Nicolas; Latrache, Iman; Yerna, Xavier; Noppe, Gauthier; Horman, Sandrine; Morel, Nicole

    2013-01-01

    Highlights: •The three ERM proteins are expressed in vascular smooth muscle cell. •ERM depletion inhibited PDGF-evoked migration redundantly. •ERM depletion increased cell adhesion redundantly. •ERM depletion did not affect PDGF-evoked Ca signal, Rac1 activation, proliferation. •ERM proteins control PDGF-induced migration by regulating adhesion. -- Abstract: Ezrin, radixin, and moesin possess a very similar structure with a C-terminal actin-binding domain and a N-terminal FERM interacting domain. They are known to be involved in cytoskeleton organization in several cell types but their function in vascular smooth muscle cells (VSMC) is still unknown. The aim of this study was to investigate the role of ERM proteins in cell migration induced by PDGF, a growth factor involved in pathophysiological processes like angiogenesis or atherosclerosis. We used primary cultured VSMC obtained from rat aorta, which express the three ERM proteins. Simultaneous depletion of the three ERM proteins with specific siRNAs abolished the effects of PDGF on cell architecture and migration and markedly increased cell adhesion and focal adhesion size, while these parameters were only slightly affected by depletion of ezrin, radixin or moesin alone. Rac1 activation, cell proliferation, and Ca 2+ signal in response to PDGF were unaffected by ERM depletion. These results indicate that ERM proteins exert a redundant control on PDGF-induced VSMC migration by regulating focal adhesion turn-over and cell adhesion to substrate

  1. Redundant control of migration and adhesion by ERM proteins in vascular smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Baeyens, Nicolas; Latrache, Iman; Yerna, Xavier [Laboratory of Cell Physiology, IoNS, Université Catholique de Louvain (Belgium); Noppe, Gauthier; Horman, Sandrine [Pôle de Recherche Cardiovasculaire, IREC, Université Catholique de Louvain (Belgium); Morel, Nicole, E-mail: nicole.morel@uclouvain.be [Laboratory of Cell Physiology, IoNS, Université Catholique de Louvain (Belgium)

    2013-11-22

    Highlights: •The three ERM proteins are expressed in vascular smooth muscle cell. •ERM depletion inhibited PDGF-evoked migration redundantly. •ERM depletion increased cell adhesion redundantly. •ERM depletion did not affect PDGF-evoked Ca signal, Rac1 activation, proliferation. •ERM proteins control PDGF-induced migration by regulating adhesion. -- Abstract: Ezrin, radixin, and moesin possess a very similar structure with a C-terminal actin-binding domain and a N-terminal FERM interacting domain. They are known to be involved in cytoskeleton organization in several cell types but their function in vascular smooth muscle cells (VSMC) is still unknown. The aim of this study was to investigate the role of ERM proteins in cell migration induced by PDGF, a growth factor involved in pathophysiological processes like angiogenesis or atherosclerosis. We used primary cultured VSMC obtained from rat aorta, which express the three ERM proteins. Simultaneous depletion of the three ERM proteins with specific siRNAs abolished the effects of PDGF on cell architecture and migration and markedly increased cell adhesion and focal adhesion size, while these parameters were only slightly affected by depletion of ezrin, radixin or moesin alone. Rac1 activation, cell proliferation, and Ca{sup 2+} signal in response to PDGF were unaffected by ERM depletion. These results indicate that ERM proteins exert a redundant control on PDGF-induced VSMC migration by regulating focal adhesion turn-over and cell adhesion to substrate.

  2. Scalloped a member of the Hippo tumor suppressor pathway controls mushroom body size in Drosophila brain by non-canonical regulation of neuroblast proliferation.

    Science.gov (United States)

    Rohith, Basavanahalli Nanjundaiah; Shyamala, Baragur Venkatanarayanasetty

    2017-12-15

    Cell proliferation, growth and survival are three different basic processes which converge at determining a fundamental property -the size of an organism. Scalloped (Sd) is the first characterised transcriptional partner to Yorkie (Yki), the downstream effector of the Hippo pathway which is a highly potential and evolutionarily conserved regulator of organ size. Here we have studied the hypomorphic effect of sd on the development of Mushroom Bodies (MBs) in Drosophila brain. We show that, sd non-function results in an increase in the size of MBs. We demonstrate that, sd regulation on MB size operates through multiple routes. Sd expressed in the differentiated MB neurons, imposes non-cell autonomous repression on the proliferation of MB precursor cells, and Sd expression in the MB neuroblasts (NB) cell autonomously represses mushroom body neuroblast (MBNB) proliferation. Further Sd in Kenyon cells (KCs) imparts a cell autonomous restriction on their growth. Our findings are distinctive because, while the classical sd loss of function phenotypes in eye, wing and lymph gland are reported as loss of tissue or reduced organ size, the present study shows that, Sd inactivation in the developing MB, promotes precursor cell proliferation and results in an increase in the organ size. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Feedforward Coordinate Control of a Robotic Cell Injection Catheter.

    Science.gov (United States)

    Cheng, Weyland; Law, Peter K

    2017-08-01

    Remote and robotically actuated catheters are the stepping-stones toward autonomous catheters, where complex intravascular procedures may be performed with minimal intervention from a physician. This article proposes a concept for the positional, feedforward control of a robotically actuated cell injection catheter used for the injection of myogenic or undifferentiated stem cells into the myocardial infarct boundary zones of the left ventricle. The prototype for the catheter system was built upon a needle-based catheter with a single degree of deflection, a 3-D printed handle combined with actuators, and the Arduino microcontroller platform. A bench setup was used to mimic a left ventricle catheter procedure starting from the femoral artery. Using Matlab and the open-source video modeling tool Tracker, the planar coordinates ( y, z) of the catheter position were analyzed, and a feedforward control system was developed based on empirical models. Using the Student's t test with a sample size of 26, it was determined that for both the y- and z-axes, the mean discrepancy between the calibrated and theoretical coordinate values had no significant difference compared to the hypothetical value of µ = 0. The root mean square error of the calibrated coordinates also showed an 88% improvement in the z-axis and 31% improvement in the y-axis compared to the unmodified trial run. This proof of concept investigation leads to the possibility of further developing a feedfoward control system in vivo using catheters with omnidirectional deflection. Feedforward positional control allows for more flexibility in the design of an automated catheter system where problems such as systemic time delay may be a hindrance in instances requiring an immediate reaction.

  4. Size-dependent effects of tungsten carbide-cobalt particles on oxygen radical production and activation of cell signaling pathways in murine epidermal cells

    International Nuclear Information System (INIS)

    Ding, M.; Kisin, E.R.; Zhao, J.; Bowman, L.; Lu, Y.; Jiang, B.; Leonard, S.; Vallyathan, V.; Castranova, V.; Murray, A.R.; Fadeel, B.; Shvedova, A.A.

    2009-01-01

    Hard metal or cemented carbide consists of a mixture of tungsten carbide (WC) (85%) and metallic cobalt (Co) (5-15%). WC-Co is considered to be potentially carcinogenic to humans. However, no comparison of the adverse effects of nano-sized WC-Co particles is available to date. In the present study, we compared the ability of nano- and fine-sized WC-Co particles to form free radicals and propensity to activate the transcription factors, AP-1 and NF-κB, along with stimulation of mitogen-activated protein kinase (MAPK) signaling pathways in a mouse epidermal cell line (JB6 P + ). Our results demonstrated that nano-WC-Co generated a higher level of hydroxyl radicals, induced greater oxidative stress, as evidenced by a decrease of GSH levels, and caused faster JB6 P + cell growth/proliferation than observed after exposure of cells to fine WC-Co. In addition, nano-WC-Co activated AP-1 and NF-κB more efficiently in JB6 +/+ cells as compared to fine WC-Co. Experiments using AP-1-luciferase reporter transgenic mice confirmed the activation of AP-1 by nano-WC-Co. Nano- and fine-sized WC-Co particles also stimulated MAPKs, including ERKs, p38, and JNKs with significantly higher potency of nano-WC-Co. Finally, co-incubation of the JB6 +/+ cells with N-acetyl-cysteine decreased AP-1 activation and phosphorylation of ERKs, p38 kinase, and JNKs, thus suggesting that oxidative stress is involved in WC-Co-induced toxicity and AP-1 activation.

  5. Nanotopographical Control of Stem Cell Differentiation

    Directory of Open Access Journals (Sweden)

    Laura E. McNamara

    2010-01-01

    Full Text Available Stem cells have the capacity to differentiate into various lineages, and the ability to reliably direct stem cell fate determination would have tremendous potential for basic research and clinical therapy. Nanotopography provides a useful tool for guiding differentiation, as the features are more durable than surface chemistry and can be modified in size and shape to suit the desired application. In this paper, nanotopography is examined as a means to guide differentiation, and its application is described in the context of different subsets of stem cells, with a particular focus on skeletal (mesenchymal stem cells. To address the mechanistic basis underlying the topographical effects on stem cells, the likely contributions of indirect (biochemical signal-mediated and direct (force-mediated mechanotransduction are discussed. Data from proteomic research is also outlined in relation to topography-mediated fate determination, as this approach provides insight into the global molecular changes at the level of the functional effectors.

  6. Hierarchical control of vehicular fuel cell / battery hybrid powertrain

    OpenAIRE

    Xu, Liangfei; Ouyang, Minggao; Li, Jianqiu; Hua, Jianfeng

    2010-01-01

    In a proton exchange membrane (PEM) fuel cell/battery hybrid vehicle, a fuel cell system fulfills the stationary power demand, and a traction battery provides the accelerating power and recycles braking energy. The entire system is coordinated by a distributed control system, incorporating three key strategies: 1) vehicle control, 2) fuel cell control and 3) battery management. They make up a hierarchical control system. This paper introduces a hierarchical control strategy for a fuel cell / ...

  7. P27 in cell cycle control and cancer

    DEFF Research Database (Denmark)

    Møller, Michael Boe

    2000-01-01

    In order to survive, cells need tight control of cell cycle progression. The control mechanisms are often lost in human cancer cells. The cell cycle is driven forward by cyclin-dependent kinases (CDKs). The CDK inhibitors (CKIs) are important regulators of the CDKs. As the name implies, CKIs were...

  8. Control of proliferation and osteogenic differentiation of human dental-pulp-derived stem cells by distinct surface structures.

    Science.gov (United States)

    Kolind, K; Kraft, D; Bøggild, T; Duch, M; Lovmand, J; Pedersen, F S; Bindslev, D A; Bünger, C E; Foss, M; Besenbacher, F

    2014-02-01

    The ability to control the behavior of stem cells provides crucial benefits, for example, in tissue engineering and toxicity/drug screening, which utilize the stem cell's capacity to engineer new tissues for regenerative purposes and the testing of new drugs in vitro. Recently, surface topography has been shown to influence stem cell differentiation; however, general trends are often difficult to establish due to differences in length scales, surface chemistries and detailed surface topographies. Here we apply a highly versatile screening approach to analyze the interplay of surface topographical parameters on cell attachment, morphology, proliferation and osteogenic differentiation of human mesenchymal dental-pulp-derived stem cells (DPSCs) cultured with and without osteogenic differentiation factors in the medium (ODM). Increasing the inter-pillar gap size from 1 to 6 μm for surfaces with small pillar sizes of 1 and 2 μm resulted in decreased proliferation and in more elongated cells with long pseudopodial protrusions. The same alterations of pillar topography, up to an inter-pillar gap size of 4 μm, also resulted in enhanced mineralization of DPSCs cultured without ODM, while no significant trend was observed for DPSCs cultured with ODM. Generally, cells cultured without ODM had a larger deposition of osteogenic markers on structured surfaces relative to the unstructured surfaces than what was found when culturing with ODM. We conclude that the topographical design of biomaterials can be optimized for the regulation of DPSC differentiation and speculate that the inclusion of ODM alters the ability of the cells to sense surface topographical cues. These results are essential in order to transfer the use of this highly proliferative, easily accessible stem cell into the clinic for use in cell therapy and regenerative medicine. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Controlling the Size and Shape of the Elastin-Like Polypeptide based Micelles

    Science.gov (United States)

    Streletzky, Kiril; Shuman, Hannah; Maraschky, Adam; Holland, Nolan

    Elastin-like polypeptide (ELP) trimer constructs make reliable environmentally responsive micellar systems because they exhibit a controllable transition from being water-soluble at low temperatures to aggregating at high temperatures. It has been shown that depending on the specific details of the ELP design (length of the ELP chain, pH and salt concentration) micelles can vary in size and shape between spherical micelles with diameter 30-100 nm to elongated particles with an aspect ratio of about 10. This makes ELP trimers a convenient platform for developing potential drug delivery and bio-sensing applications as well as for understanding micelle formation in ELP systems. Since at a given salt concentration, the headgroup area for each foldon should be constant, the size of the micelles is expected to be proportional to the volume of the linear ELP available per foldon headgroup. Therefore, adding linear ELPs to a system of ELP-foldon should result in changes of the micelle volume allowing to control micelle size and possibly shape. The effects of addition of linear ELPs on size, shape, and molecular weight of micelles at different salt concentrations were studied by a combination of Dynamic Light Scattering and Static Light Scattering. The initial results on 50 µM ELP-foldon samples (at low salt) show that Rh of mixed micelles increases more than 5-fold as the amount of linear ELP raised from 0 to 50 µM. It was also found that a given mixture of linear and trimer constructs has two temperature-based transitions and therefore displays three predominant size regimes.

  10. Refined Synthesis and Characterization of Controlled Diameter, Narrow Size Distribution Microparticles for Aerospace Research Applications

    Science.gov (United States)

    Tiemsin, Pacita I.; Wohl, Christopher J.

    2012-01-01

    Flow visualization using polystyrene microspheres (PSL)s has enabled researchers to learn a tremendous amount of information via particle based diagnostic techniques. To better accommodate wind tunnel researchers needs, PSL synthesis via dispersion polymerization has been carried out at NASA Langley Research Center since the late 1980s. When utilizing seed material for flow visualization, size and size distribution are of paramount importance. Therefore, the work described here focused on further refinement of PSL synthesis and characterization. Through controlled variation of synthetic conditions (chemical concentrations, solution stirring speed, temperature, etc.) a robust, controllable procedure was developed. The relationship between particle size and salt concentration, MgSO4, was identified enabling the determination of PSL diameters a priori. Suggestions of future topics related to PSL synthesis, stability, and size variation are also described.

  11. The gram-negative bacterial periplasm: Size matters.

    Directory of Open Access Journals (Sweden)

    Samuel I Miller

    2018-01-01

    Full Text Available Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control. The periplasm also contains structural elements and important environmental sensing modules, and it allows complex nanomachines to span the cell envelope. Recent work indicates that the size or intermembrane distance of the periplasm is controlled by periplasmic lipoproteins that anchor the outer membrane to the periplasmic peptidoglycan polymer. This periplasm intermembrane distance is critical for sensing outer membrane damage and dictates length of the flagellar periplasmic rotor, which controls motility. These exciting results resolve longstanding debates about whether the periplasmic distance has a biological function and raise the possibility that the mechanisms for maintenance of periplasmic size could be exploited for antibiotic development.

  12. JNK Controls the Onset of Mitosis in Planarian Stem Cells and Triggers Apoptotic Cell Death Required for Regeneration and Remodeling

    Science.gov (United States)

    Almuedo-Castillo, María; Crespo, Xenia; Seebeck, Florian; Bartscherer, Kerstin; Salò, Emili; Adell, Teresa

    2014-01-01

    Regeneration of lost tissues depends on the precise interpretation of molecular signals that control and coordinate the onset of proliferation, cellular differentiation and cell death. However, the nature of those molecular signals and the mechanisms that integrate the cellular responses remain largely unknown. The planarian flatworm is a unique model in which regeneration and tissue renewal can be comprehensively studied in vivo. The presence of a population of adult pluripotent stem cells combined with the ability to decode signaling after wounding enable planarians to regenerate a complete, correctly proportioned animal within a few days after any kind of amputation, and to adapt their size to nutritional changes without compromising functionality. Here, we demonstrate that the stress-activated c-jun–NH2–kinase (JNK) links wound-induced apoptosis to the stem cell response during planarian regeneration. We show that JNK modulates the expression of wound-related genes, triggers apoptosis and attenuates the onset of mitosis in stem cells specifically after tissue loss. Furthermore, in pre-existing body regions, JNK activity is required to establish a positive balance between cell death and stem cell proliferation to enable tissue renewal, remodeling and the maintenance of proportionality. During homeostatic degrowth, JNK RNAi blocks apoptosis, resulting in impaired organ remodeling and rescaling. Our findings indicate that JNK-dependent apoptotic cell death is crucial to coordinate tissue renewal and remodeling required to regenerate and to maintain a correctly proportioned animal. Hence, JNK might act as a hub, translating wound signals into apoptotic cell death, controlled stem cell proliferation and differentiation, all of which are required to coordinate regeneration and tissue renewal. PMID:24922054

  13. Sorting of cells of the same size, shape, and cell cycle stage for a single cell level assay without staining

    Directory of Open Access Journals (Sweden)

    Yomo Tetsuya

    2006-06-01

    Full Text Available Abstract Background Single-cell level studies are being used increasingly to measure cell properties not directly observable in a cell population. High-performance data acquisition systems for such studies have, by necessity, developed in synchrony. However, improvements in sample purification techniques are also required to reveal new phenomena. Here we assessed a cell sorter as a sample-pretreatment tool for a single-cell level assay. A cell sorter is routinely used for selecting one type of cells from a heterogeneous mixture of cells using specific fluorescence labels. In this case, we wanted to select cells of exactly the same size, shape, and cell-cycle stage from a population, without using a specific fluorescence label. Results We used four light scatter parameters: the peak height and area of the forward scatter (FSheight and FSarea and side scatter (SSheight and SSarea. The rat pheochromocytoma PC12 cell line, a neuronal cell line, was used for all experiments. The living cells concentrated in the high FSarea and middle SSheight/SSarea fractions. Single cells without cell clumps were concentrated in the low SS and middle FS fractions, and in the higher FSheight/FSarea and SSheight/SSarea fractions. The cell populations from these viable, single-cell-rich fractions were divided into twelve subfractions based on their FSarea-SSarea profiles, for more detailed analysis. We found that SSarea was proportional to the cell volume and the FSarea correlated with cell roundness and elongation, as well as with the level of DNA in the cell. To test the method and to characterize the basic properties of the isolated single cells, sorted cells were cultured in separate wells. The cells in all subfractions survived, proliferated and differentiated normally, suggesting that there was no serious damage. The smallest, roundest, and smoothest cells had the highest viability. There was no correlation between proliferation and differentiation. NGF increases

  14. Dimensionality controls cytoskeleton assembly and metabolism of fibroblast cells in response to rigidity and shape.

    Directory of Open Access Journals (Sweden)

    Mirjam Ochsner

    2010-03-01

    Full Text Available Various physical parameters, including substrate rigidity, size of adhesive islands and micro-and nano-topographies, have been shown to differentially regulate cell fate in two-dimensional (2-D cell cultures. Cells anchored in a three-dimensional (3-D microenvironment show significantly altered phenotypes, from altered cell adhesions, to cell migration and differentiation. Yet, no systematic analysis has been performed that studied how the integrated cellular responses to the physical characteristics of the environment are regulated by dimensionality (2-D versus 3-D.Arrays of 5 or 10 microm deep microwells were fabricated in polydimethylsiloxane (PDMS. The actin cytoskeleton was compared for single primary fibroblasts adhering either to microfabricated adhesive islands (2-D or trapped in microwells (3-D of controlled size, shape, and wall rigidity. On rigid substrates (Young's Modulus = 1 MPa, cytoskeleton assembly within single fibroblast cells occurred in 3-D microwells of circular, rectangular, square, and triangular shapes with 2-D projected surface areas (microwell bottom surface area and total surface areas of adhesion (microwell bottom plus wall surface area that inhibited stress fiber assembly in 2-D. In contrast, cells did not assemble a detectable actin cytoskeleton in soft 3-D microwells (20 kPa, regardless of their shapes, but did so on flat, 2-D substrates. The dependency on environmental dimensionality was also reflected by cell viability and metabolism as probed by mitochondrial activities. Both were upregulated in 3-D cultured cells versus cells on 2-D patterns when surface area of adhesion and rigidity were held constant.These data indicate that cell shape and rigidity are not orthogonal parameters directing cell fate. The sensory toolbox of cells integrates mechanical (rigidity and topographical (shape and dimensionality information differently when cell adhesions are confined to 2-D or occur in a 3-D space.

  15. Universal entrainment mechanism controls contact times with motile cells

    Science.gov (United States)

    Mathijssen, Arnold J. T. M.; Jeanneret, Raphaël; Polin, Marco

    2018-03-01

    Contact between particles and motile cells underpins a wide variety of biological processes, from nutrient capture and ligand binding to grazing, viral infection, and cell-cell communication. The window of opportunity for these interactions depends on the basic mechanism determining contact time, which is currently unknown. By combining experiments on three different species—Chlamydomonas reinhardtii, Tetraselmis subcordiforms, and Oxyrrhis marina—with simulations and analytical modeling, we show that the fundamental physical process regulating proximity to a swimming microorganism is hydrodynamic particle entrainment. The resulting distribution of contact times is derived within the framework of Taylor dispersion as a competition between advection by the cell surface and microparticle diffusion, and predicts the existence of an optimal tracer size that is also observed experimentally. Spatial organization of flagella, swimming speed, and swimmer and tracer size influence entrainment features and provide tradeoffs that may be tuned to optimize the estimated probabilities for microbial interactions like predation and infection.

  16. KIDNEY SIZE IN INFANTS OF TIGHTLY CONTROLLED INSULIN-DEPENDENT DIABETIC MOTHERS

    NARCIS (Netherlands)

    BOS, AF; AALDERS, AL; VANDOORMAAL, JJ; MARTIJN, A; OKKEN, A

    The aim of this study was to evaluate the influence of insulin-dependent diabetes mellitus in pregnant women on the kidney size of their infants. We measured kidney length in the first week of life using ultrasonography in 20 infants of tightly controlled insulin-dependent diabetic mothers and 20

  17. Granule size control and targeting in pulsed spray fluid bed granulation.

    Science.gov (United States)

    Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

    2009-07-30

    The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

  18. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping

    KAUST Repository

    Wang, Feng

    2010-02-25

    Doping is a widely applied technological process in materials science that involves incorporating atoms or ions of appropriate elements into host lattices to yield hybrid materials with desirable properties and functions. For nanocrystalline materials, doping is of fundamental importance in stabilizing a specific crystallographic phase, modifying electronic properties, modulating magnetism as well as tuning emission properties. Here we describe a material system in which doping influences the growth process to give simultaneous control over the crystallographic phase, size and optical emission properties of the resulting nanocrystals. We show that NaYF 4 nanocrystals can be rationally tuned in size (down to ten nanometres), phase (cubic or hexagonal) and upconversion emission colour (green to blue) through use of trivalent lanthanide dopant ions introduced at precisely defined concentrations. We use first-principles calculations to confirm that the influence of lanthanide doping on crystal phase and size arises from a strong dependence on the size and dipole polarizability of the substitutional dopant ion. Our results suggest that the doping-induced structural and size transition, demonstrated here in NaYF 4 upconversion nanocrystals, could be extended to other lanthanide-doped nanocrystal systems for applications ranging from luminescent biological labels to volumetric three-dimensional displays. © 2010 Macmillan Publishers Limited. All rights reserved.

  19. Muscle Stem Cell Fate Is Controlled by the Cell-Polarity Protein Scrib

    Directory of Open Access Journals (Sweden)

    Yusuke Ono

    2015-02-01

    Full Text Available Satellite cells are resident skeletal muscle stem cells that supply myonuclei for homeostasis, hypertrophy, and repair in adult muscle. Scrib is one of the major cell-polarity proteins, acting as a potent tumor suppressor in epithelial cells. Here, we show that Scrib also controls satellite-cell-fate decisions in adult mice. Scrib is undetectable in quiescent cells but becomes expressed during activation. Scrib is asymmetrically distributed in dividing daughter cells, with robust accumulation in cells committed to myogenic differentiation. Low Scrib expression is associated with the proliferative state and preventing self-renewal, whereas high Scrib levels reduce satellite cell proliferation. Satellite-cell-specific knockout of Scrib in mice causes a drastic and insurmountable defect in muscle regeneration. Thus, Scrib is a regulator of tissue stem cells, controlling population expansion and self-renewal with Scrib expression dynamics directing satellite cell fate.

  20. The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

    Science.gov (United States)

    Dunne, Peter W.; Starkey, Chris L.; Gimeno-Fabra, Miquel; Lester, Edward H.

    2014-01-01

    Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control. Electronic supplementary information (ESI) available: Experimental details, refinement procedure, fluorescence spectra of ZnS samples. See DOI: 10.1039/c3nr05749f

  1. The effects of ultraviolet light on host cell reactivation and plaque size of Herpes simplex virus type 1 in C3H/10T1/2 mouse cells

    International Nuclear Information System (INIS)

    Montes, J.G.; Taylor, W.D.

    1986-01-01

    Herpes simplex virus-type 1 (HSV-1) plaque-forming ability and plaque size were measured on (C3H/10T1/2) cell monolayers as functions of pretreatment dose with UV light at different times before inoculation with virus, in order to determine if UV-enhanced reactivation (ER) of UV-irradiated virus, as well as associated phenomena, could be obtained in this cell system. The number of virus plaques observed (i.e. the capacity of the cells to support virus growth) and the size of the plaques were found to increase substantially with pretreatment of the cells with UV light. However, no significant ER was observed. Therefore, the mechanisms responsible for the increases in plaque size and cell capacity seem to be independent of those responsible for ER. In work by others, C3H/10T1/2 cells have been transformed by UV light at doses similar to those used in this study; the absence of ER of UV-irradiated virus in this study indicates that the mechanism underlying ER is not required for transformation. (author)

  2. Testosterone replacement alters the cell size in visceral fat but not in subcutaneous fat in hypogonadal aged male rats as a late-onset hypogonadism animal model

    Directory of Open Access Journals (Sweden)

    Abdelhamed A

    2015-03-01

    Full Text Available Amr Abdelhamed,1,2 Shin-ichi Hisasue,1 Masato Shirai,3 Kazuhito Matsushita,1 Yoshiaki Wakumoto,1 Akira Tsujimura,1 Taiji Tsukamoto,4 Shigeo Horie1 1Department of Urology, Juntendo University, Graduate School of Medicine, Tokyo, Japan; 2Department of Dermatology, Venereology and Andrology, Sohag University, Graduate School of Medicine, Sohag, Egypt; 3Department of Urology, Juntendo University Urayasu Hospital, Urayasu, Japan; 4Department of Urology, School of Medicine, Sapporo Medical University, Sapporo, Japan Background: Patients with late-onset hypogonadism (LOH benefit from testosterone replacement by improvement in the parameters of the metabolic syndrome, but fat cell morphology in these patients is still unclear. This study aims to determine the effect of testosterone replacement on the morphology of fat cells in subcutaneous and visceral adipose tissue and on erectile function in hypogonadal aged male rats as a model of LOH. Methods: Ten male Sprague-Dawley rats aged 20–22 months were randomly allocated to two groups, ie, aged male controls (control group, n=5 and aged males treated with testosterone replacement therapy (TRT group, n=5. Testosterone enanthate 25 mg was injected subcutaneously every 2 weeks for 6 weeks. At 6 weeks, the intracavernous pressure (ICP and mean arterial blood pressure (MAP ratio was assessed. Visceral and subcutaneous adipose tissue specimens were collected and analyzed using Image-J software. Results: Body weight at 2, 4, and 6 weeks after TRT was 800.0±35.4 g, 767.5±46.3 g, and 780±40.4 g, respectively (not statistically significant. The ICP/MAP ratio was 0.341±0.015 in the TRT group and 0.274±0.049 in the control group (not statistically significant. The median subcutaneous fat cell size was 4.85×103 (range 0.85–12.53×103 µm2 in the control group and 4.93×103 (range 6.42–19.7×103 µm2 in the TRT group (not statistically significant. In contrast, median visceral fat cell size was significantly

  3. Cell culture arrays using micron-sized ferromagnetic ring-shaped thin films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chen-Yu; Wei, Zung-Hang, E-mail: wei@pme.nthu.edu.tw [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City 300, Taiwan (China); Lai, Mei-Feng; Ger, Tzong-Rong [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu City 300, Taiwan (China)

    2015-05-07

    Cell patterning has become an important technology for tissue engineering. In this research, domain walls are formed at the two ends of a ferromagnetic ring thin film after applying a strong external magnetic field, which can effectively attract magnetically labeled cells and control the position for biological cell. Magnetophoresis experiment was conducted to quantify the magnetic nanoparticle inside the cells. A ring-shaped magnetic thin films array was fabricated through photolithography. It is observed that magnetically labeled cells can be successfully attracted to the two ends of the ring-shaped magnetic thin film structure and more cells were attracted and further attached to the structures. The cells are co-cultured with the structure and kept proliferating; therefore, such ring thin film can be an important candidate for in-vitro biomedical chips or tissue engineering.

  4. Cell culture arrays using micron-sized ferromagnetic ring-shaped thin films

    International Nuclear Information System (INIS)

    Huang, Chen-Yu; Wei, Zung-Hang; Lai, Mei-Feng; Ger, Tzong-Rong

    2015-01-01

    Cell patterning has become an important technology for tissue engineering. In this research, domain walls are formed at the two ends of a ferromagnetic ring thin film after applying a strong external magnetic field, which can effectively attract magnetically labeled cells and control the position for biological cell. Magnetophoresis experiment was conducted to quantify the magnetic nanoparticle inside the cells. A ring-shaped magnetic thin films array was fabricated through photolithography. It is observed that magnetically labeled cells can be successfully attracted to the two ends of the ring-shaped magnetic thin film structure and more cells were attracted and further attached to the structures. The cells are co-cultured with the structure and kept proliferating; therefore, such ring thin film can be an important candidate for in-vitro biomedical chips or tissue engineering

  5. Grain size controls on sediment supply from debris-mantled dryland hillslopes

    Science.gov (United States)

    Michaelides, K.

    2011-12-01

    characteristics, determine sediment transport dynamics and net flux, GSD supplied to the slope base and the changes in GSD on the hillslope. The results show a strong control of initial hillslope GSD on flux characteristics: (1) GSD controls the degree of non-linearity in the relationship between sediment flux and hillslope gradient. (2) Grain size uniformity controls the degree and form of non-linearity in the relationship between sediment flux and gradient. (3) Over multiple runoff events, slopes coarsen - steeper slopes become coarser than shallow slopes. For individual events, changes in GSD on the slope depend on the magnitude and duration of the runoff event and can result in variable coarsening and fining on different parts of the slope. (4) The GSD of sediment delivered to the slope base is dependent on the hillslope GSD and the hillslope attributes and runoff characteristics. For most runoff events, the GSD of fluxed sediment is finer than the hillslope GSD except for extreme runoff events on very steep slopes with intermediate GSD (not extremely coarse). These findings provide insights into hillslope responses to climatic forcing and have theoretical implications for modeling hillslope evolution in drylands.

  6. Scalable fabrication of size-controlled chitosan nanoparticles for oral delivery of insulin.

    Science.gov (United States)

    He, Zhiyu; Santos, Jose Luis; Tian, Houkuan; Huang, Huahua; Hu, Yizong; Liu, Lixin; Leong, Kam W; Chen, Yongming; Mao, Hai-Quan

    2017-06-01

    Controlled delivery of protein would find diverse therapeutic applications. Formulation of protein nanoparticles by polyelectrolyte complexation between the protein and a natural polymer such as chitosan (CS) is a popular approach. However, the current method of batch-mode mixing faces significant challenges in scaling up while maintaining size control, high uniformity, and high encapsulation efficiency. Here we report a new method, termed flash nanocomplexation (FNC), to fabricate insulin nanoparticles by infusing aqueous solutions of CS, tripolyphosphate (TPP), and insulin under rapid mixing condition (Re > 1600) in a multi-inlet vortex mixer. In comparison with the bulk-mixing method, the optimized FNC process produces CS/TPP/insulin nanoparticles with a smaller size (down to 45 nm) and narrower size distribution, higher encapsulation efficiency (up to 90%), and pH-dependent nanoparticle dissolution and insulin release. The CS/TPP/insulin nanoparticles can be lyophilized and reconstituted without loss of activity, and produced at a throughput of 5.1 g h -1 when a flow rate of 50 mL min -1 is used. Evaluated in a Type I diabetes rat model, the smaller nanoparticles (45 nm and 115 nm) control the blood glucose level through oral administration more effectively than the larger particles (240 nm). This efficient, reproducible and continuous FNC technique is amenable to scale-up in order to address the critical barrier of manufacturing for the translation of protein nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Crystal size control of sulfathiazole using high pressure carbon dioxide

    Science.gov (United States)

    Kitamura, M.; Yamamoto, M.; Yoshinaga, Y.; Masuoka, H.

    1997-07-01

    The effect of the pressurization method of carbon dioxide on the crystallization behavior and crystal size of sulphathiazole (SUT) was investigated. In the "stepwise pressurization" method exceptionally large pillar-like crystals of 2-6 mm were obtained as mainly a scaling on the wall of the crystallizer. In the "rapid pressurization" method, crystals with a size one third to half of that obtained in the stepwise method precipitated, indicating the accelerated nucleation rate by the rapid increase of the supersaturation degree with a vigorous bubbling. With the new method of "two-step pressurization", in the first step the nucleation is accelerated with a much larger pressure instantly created, and in the second step the growth rate is retarded with the lower pressure. By this method much more fine crystals (from a few tens to several hundred micrometers) were produced and the scaling was suppressed. In this method a large supersaturation degree at an interface between the gas (bubble) and liquid phase under a vigorous bubbling may play an important role in accelerating the nucleation. The average size of the crystals tended to become smaller with increase of the first pressure and the expansion ratio at a decompression point, and it tended to get larger with increase of the second pressure. These results show that the GAS method is very useful for the control of crystal size over a wide range.

  8. Analytical investigation on cell temperature control method of planar solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Inui, Y.; Ito, N.; Nakajima, T.; Urata, A. [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Tempaku-cho, Toyohashi (Japan)

    2006-09-15

    The solid oxide fuel cell (SOFC) has a problem in durability of the ceramics used as its cell materials because its operating temperature is very high and the cell temperature fluctuation induces thermal stress in the ceramics. The cell temperature distribution in the SOFC, therefore, should be kept as constant as possible during variable load operation through control of the average current density in the cell. Considering this fact, the authors numerically optimize the operating parameters of air utilization and the inlet gas temperature of the planar SOFC by minimizing the cell temperature shift from its nominal value and propose a new cell temperature control method that adopts these optimum operating parameters for each average current density. The effectiveness of the proposed method is very high and the temperature variation is suppressed to a very low level without lowering the single cell voltage for both the co-flow and counter-flow type cells, indicating that the proposed cell temperature control method makes variable load operation of the planar SOFC possible. (author)

  9. Sample size calculation while controlling false discovery rate for differential expression analysis with RNA-sequencing experiments.

    Science.gov (United States)

    Bi, Ran; Liu, Peng

    2016-03-31

    RNA-Sequencing (RNA-seq) experiments have been popularly applied to transcriptome studies in recent years. Such experiments are still relatively costly. As a result, RNA-seq experiments often employ a small number of replicates. Power analysis and sample size calculation are challenging in the context of differential expression analysis with RNA-seq data. One challenge is that there are no closed-form formulae to calculate power for the popularly applied tests for differential expression analysis. In addition, false discovery rate (FDR), instead of family-wise type I error rate, is controlled for the multiple testing error in RNA-seq data analysis. So far, there are very few proposals on sample size calculation for RNA-seq experiments. In this paper, we propose a procedure for sample size calculation while controlling FDR for RNA-seq experimental design. Our procedure is based on the weighted linear model analysis facilitated by the voom method which has been shown to have competitive performance in terms of power and FDR control for RNA-seq differential expression analysis. We derive a method that approximates the average power across the differentially expressed genes, and then calculate the sample size to achieve a desired average power while controlling FDR. Simulation results demonstrate that the actual power of several popularly applied tests for differential expression is achieved and is close to the desired power for RNA-seq data with sample size calculated based on our method. Our proposed method provides an efficient algorithm to calculate sample size while controlling FDR for RNA-seq experimental design. We also provide an R package ssizeRNA that implements our proposed method and can be downloaded from the Comprehensive R Archive Network ( http://cran.r-project.org ).

  10. Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

    International Nuclear Information System (INIS)

    Devanand Venkatasubbu, G.; Ramasamy, S.; Avadhani, G. S.; Palanikumar, L.; Kumar, J.

    2012-01-01

    Nanoparticles are highly used in biological applications including nanomedicine. In this present study, the interaction of HepG2 hepatocellular carcinoma cells (HCC) with hydroxyapatite (HAp), zinc-doped hydroxyapatite, and titanium dioxide (TiO 2 ) nanoparticles were investigated. Hydroxyapatite, zinc-doped hydroxyapatite and titanium dioxide nanoparticles were prepared by wet precipitation method. They were subjected to isochronal annealing at different temperatures. Particle morphology and size distribution were characterized by X-ray diffraction and transmission electron microscope. The nanoparticles were co-cultured with HepG2 cells. MTT assay was employed to evaluate the proliferation of tumor cells. The DNA damaging effect of HAp, Zn-doped HAp, and TiO 2 nanoparticles in human hepatoma cells (HepG2) were evaluated using DNA fragmentation studies. The results showed that in HepG2 cells, the anti-tumor activity strongly depend on the size of nanoparticles in HCC cells. Cell cycle arrest analysis for HAp, zinc-doped HAp, and TiO 2 nanoparticles revealed the influence of HAp, zinc-doped HAp, and titanium dioxide nanoparticles on the apoptosis of HepG2 cells. The results imply that the novel nano nature effect plays an important role in the biomedicinal application of nanoparticles.

  11. Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

    Science.gov (United States)

    Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W.; Gimble, Jeffrey M.; Hayes, Daniel J.

    2015-04-01

    Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell-particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix.

  12. Single-crystalline ceria nanocubes: size-controlled synthesis, characterization and redox property

    International Nuclear Information System (INIS)

    Yang Zhiqiang; Zhou Kebin; Liu Xiangwen; Tian Qun; Lu Deyi; Yang Sen

    2007-01-01

    Single-crystalline CeO 2 nanocubes were synthesized through a hydrothermal treatment. By varying reaction temperature and the NaOH concentration, the size control of CeO 2 nanocubes has been achieved, which produces the nanocubes with a controllable edge length in the regime of 20-360 nm. HRTEM studies reveal that the CeO 2 nanocubes expose their high energy {001} planes. Consequently, it is demonstrated that the CeO 2 nanocubes exhibit excellent reducibility and high oxygen storage capacity, indicating they are potential novel catalytic materials

  13. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea

    DEFF Research Database (Denmark)

    Braun, Stefan; Morono, Yuki; Littmann, Sten

    2016-01-01

    determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density......-specific carbon content was 19–31 fg C cell−1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm−3, suggesting that cells decrease their water content and grow...... small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates...

  14. Colloidal nanoparticle size control: experimental and kinetic modeling investigation of the ligand-metal binding role in controlling the nucleation and growth kinetics.

    Science.gov (United States)

    Mozaffari, Saeed; Li, Wenhui; Thompson, Coogan; Ivanov, Sergei; Seifert, Soenke; Lee, Byeongdu; Kovarik, Libor; Karim, Ayman M

    2017-09-21

    Despite the major advancements in colloidal metal nanoparticles synthesis, a quantitative mechanistic treatment of the ligand's role in controlling their size remains elusive. We report a methodology that combines in situ small angle X-ray scattering (SAXS) and kinetic modeling to quantitatively capture the role of ligand-metal binding (with the metal precursor and the nanoparticle surface) in controlling the synthesis kinetics. We demonstrate that accurate extraction of the kinetic rate constants requires using both, the size and number of particles obtained from in situ SAXS to decouple the contributions of particle nucleation and growth to the total metal reduction. Using Pd acetate and trioctylphosphine in different solvents, our results reveal that the binding of ligands with both the metal precursor and nanoparticle surface play a key role in controlling the rates of nucleation and growth and consequently the final size. We show that the solvent can affect the metal-ligand binding and consequently ligand coverage on the nanoparticles surface which has a strong effect on the growth rate and final size (1.4 nm in toluene and 4.3 nm in pyridine). The proposed kinetic model quantitatively predicts the effects of varying the metal concentration and ligand/metal ratio on nanoparticle size for our work and literature reports. More importantly, we demonstrate that the final size is exclusively determined by the nucleation and growth kinetics at early times and not how they change with time. Specifically, the nanoparticle size in this work and many literature reports can be predicted using a single, model independent kinetic descriptor, (growth-to-nucleation rate ratio) 1/3 , despite the different metals and synthetic conditions. The proposed model and kinetic descriptor could serve as powerful tools for the design of colloidal nanoparticles with specific sizes.

  15. One-pot size and shape controlled synthesis of DMSO capped iron ...

    Indian Academy of Sciences (India)

    Size and shape of the capped iron oxide nanoparticles are well controlled by simply ... quently used to synthesize magnetic ferrites from different iron precursors ... added to the mixture resulting in a dark brown precipitate. Figure 2. (a–c). TG–DTA .... Doyle P S, Bibette J, Bancaud A and Viovy J L 2002 Science. 295 2237.

  16. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    International Nuclear Information System (INIS)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei

    2010-01-01

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 μm and an average porosity of 48.26 ± 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  17. Distributed active traction control system applied to the RoboCup middle size league

    OpenAIRE

    Almeida, José; Dias, André; Sequeira, João; Martins, Alfredo; Silva, Eduardo

    2013-01-01

    This work addresses the problem of traction control in mobile wheeled robots in the particular case of the RoboCup Middle Size League (MSL). The slip control problem is formulated using simple friction models for ISePorto Team robots with a differential wheel configuration. Traction was also characterized experimentally in the MSL scenario for relevant game events. This work proposes a hierarchical traction control architecture which relies in local slip detection and con...

  18. The control and execution of programmed cell death

    International Nuclear Information System (INIS)

    Begum, R.; Pathak, N.; Hasnain, S.E.; Sah, N.K.; Athar, M.

    1999-01-01

    Apoptosis or programmed cell death is a highly conserved genetically controlled response of metazoan cells to commit suicide. Non apoptotic programmed cell death seems to operate in single celled eukaryotes implying that evolution of PCD has preceded the evolution of multicellularity. PCD plays a crucial role in the regulation of cellular and tissue homeostasis and any aberrations in apoptosis leads to several diseases including cancer, neurodegenerative disorders and AIDS. The mechanisms by which apoptosis is controlled are varied. In some cells, members of bcl-2 family or p53 are crucial for regulating the apoptosis programme, whereas in other cells Fas ligand is more important. bcl-2 family members have a prime role in the regulation of cell death at all stages including development, whereas cell death during development is independent of p53. bcl-2 family members being localized on the outer mitochondrial membrane, control the mitochondrial homeostasis and cytochrome c redistribution and thereby regulate the cell death process. p53 promotes DNA damage mediated cell death after growth arrest and failed DNA repair. Caspases play a key role in the execution of cell death by mediating highly specific cleavages of crucial cellular proteins collectively manifesting the apoptotic phenotype. Protein inhibitors like crm A, p35 and IAPs could prevent/control apoptosis induced by a broad array of cell death stimuli by several mechanisms specially interfering in caspase activation or caspase activity. Among endonucleases, caspase activated DNase (CAD) plays a crucial role in DNA fragmentation, a biochemical hallmark of apoptosis. As regulation of cell death seems to be as complex as regulation of cell proliferation, multiple kinase mediated regulatory mechanisms might control the apoptotic process. Thus, in spite of intensive research over the past few years, the field of apoptosis still remains fertile to unravel among others, the molecular mechanisms of cytochrome c

  19. The control and execution of programmed cell death

    Energy Technology Data Exchange (ETDEWEB)

    Begum, R.; Pathak, N.; Hasnain, S.E.; Sah, N.K. [National Inst. of Immunology, New Delhi (India). Eukaryotic Gene Expression Lab.; Taneja, T.K.; Mohan, M. [National Inst. of Immunology, New Delhi (India). Eukaryotic Gene Expression Lab.]|[Dept. of Medical Elementology and Toxicology, New Delhi (India); Athar, M. [Dept. of Medical Elementology and Toxicology, New Delhi (India)

    1999-07-01

    Apoptosis or programmed cell death is a highly conserved genetically controlled response of metazoan cells to commit suicide. Non apoptotic programmed cell death seems to operate in single celled eukaryotes implying that evolution of PCD has preceded the evolution of multicellularity. PCD plays a crucial role in the regulation of cellular and tissue homeostasis and any aberrations in apoptosis leads to several diseases including cancer, neurodegenerative disorders and AIDS. The mechanisms by which apoptosis is controlled are varied. In some cells, members of bcl-2 family or p53 are crucial for regulating the apoptosis programme, whereas in other cells Fas ligand is more important. bcl-2 family members have a prime role in the regulation of cell death at all stages including development, whereas cell death during development is independent of p53. bcl-2 family members being localized on the outer mitochondrial membrane, control the mitochondrial homeostasis and cytochrome c redistribution and thereby regulate the cell death process. p53 promotes DNA damage mediated cell death after growth arrest and failed DNA repair. Caspases play a key role in the execution of cell death by mediating highly specific cleavages of crucial cellular proteins collectivley manifesting the apoptotic phenotype. Protein inhibitors like crm A, p35 and IAPs could prevent/control apoptosis induced by a broad array of cell death stimuli by several mechanisms specially interfering in caspase activation or caspase activity. Among endonucleases, caspase activated DNase (CAD) plays a crucial role in DNA fragmentation, a biochemical hallmark of apoptosis. As regulation of cell death seems to be as complex as regulation of cell proliferation, multiple kinase mediated regulatory mechanisms might control the apoptotic process. Thus, in spite of intensive research over the past few years, the field of apoptosis still remains fertile to unravel among others, the molecular mechanisms of cytochrome c

  20. The Impact of Tumor Size on Outcomes After Stereotactic Body Radiation Therapy for Medically Inoperable Early-Stage Non-Small Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Allibhai, Zishan [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Taremi, Mojgan [Department of Radiation Oncology, Stronach Regional Cancer Centre, Newmarket (Canada); Bezjak, Andrea; Brade, Anthony; Hope, Andrew J.; Sun, Alexander [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Cho, B.C. John, E-mail: john.cho@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada)

    2013-12-01

    Purpose: Stereotactic body radiation therapy for medically inoperable early-stage non-small cell lung cancer (NSCLC) offers excellent control rates. Most published series deal mainly with small (usually <4 cm), peripheral, solitary tumors. Larger tumors are associated with poorer outcomes (ie, lower control rates, higher toxicity) when treated with conventional RT. It is unclear whether SBRT is sufficiently potent to control these larger tumors. We therefore evaluated and examined the influence of tumor size on treatment outcomes after SBRT. Methods and Materials: Between October 2004 and October 2010, 185 medically inoperable patients with early (T1-T2N0M0) NSCLC were treated on a prospective research ethics board-approved single-institution protocol. Prescription doses were risk-adapted based on tumor size and location. Follow-up included prospective assessment of toxicity (as per Common Terminology Criteria for Adverse Events, version 3.0) and serial computed tomography scans. Patterns of failure, toxicity, and survival outcomes were calculated using Kaplan-Meier method, and the significance of tumor size (diameter, volume) with respect to patient, treatment, and tumor factors was tested. Results: Median follow-up was 15.2 months. Tumor size was not associated with local failure but was associated with regional failure (P=.011) and distant failure (P=.021). Poorer overall survival (P=.001), disease-free survival (P=.001), and cause-specific survival (P=.005) were also significantly associated with tumor size (with tumor volume more significant than diameter). Gross tumor volume and planning target volume were significantly associated with grade 2 or worse radiation pneumonitis. However, overall rates of grade ≥3 pneumonitis were low and not significantly affected by tumor or target size. Conclusions: Currently employed stereotactic body radiation therapy dose regimens can provide safe effective local therapy even for larger solitary NSCLC tumors (up to 5.7 cm

  1. Distribution of Mast Cells and Locations, Depths, and Sizes of the Putative Acupoints CV 8 and KI 16

    Directory of Open Access Journals (Sweden)

    Sharon Jiyoon Jung

    2017-01-01

    Full Text Available The anatomical locations and sizes of acupuncture points (APs are identified in traditional Chinese medicine by using the cun measurement method. More precise knowledge of those locations and sizes to submillimeter precision, along with their cytological characterizations, would provide significant contributions both to scientific investigations and to precise control of the practice of acupuncture. Over recent decades, researchers have come to realize that APs in the skin of rats and humans have more mast cells (MCs than neighboring nonacupoints. In this work, the distribution of MCs in the ventral skin of mice was studied so that it could be used to infer the locations, depths from the epidermis, and sizes of three putative APs. The umbilicus was taken as the reference point, and a transversal cross section through it was studied. The harvested skins from 8-week-old mice were stained with toluidine blue, and the MCs were recognized by their red-purple stains and their metachromatic granules. The three putative APs, CV 8 and the left and the right KI 16 APs, were identified based on their high densities of MCs. These findings also imply that acupuncture may stimulate, through MCs, an immune response to allergic inflammation.

  2. Effect of selenium nanoparticles with different sizes in primary cultured intestinal epithelial cells of crucian carp, Carassius auratus gibelio

    Directory of Open Access Journals (Sweden)

    Wang YB

    2013-10-01

    Full Text Available Yanbo Wang, Xuxia Yan, Linglin Fu Marine Resources and Nutrition Biology Research Center, Food Quality and Safety Department, Zhejiang Gongshang University, Hangzhou, People's Republic of China Abstract: Nano-selenium (Se, with its high bioavailability and low toxicity, has attracted wide attention for its potential application in the prevention of oxidative damage in animal tissues. However, the effect of nano-Se of different sizes on the intestinal epithelial cells of the crucian carp (Carassius auratus gibelio is poorly understood. Our study showed that different sizes and doses of nano-Se have varied effects on the cellular protein contents and the enzyme activities of secreted lactate dehydrogenase, intracellular sodium potassium adenosine triphosphatase, glutathione peroxidase, and superoxide dismutase. It was also indicated that nano-Se had a size-dependent effect on the primary intestinal epithelial cells of the crucian carp. Thus, these findings may bring us a step closer to understanding the size effect and the bioavailability of nano-Se on the intestinal tract of the crucian carp. Keywords: selenium nanoparticle, intestinal epithelial cell, crucian carp, primary culture

  3. Cell cycle controls: potential targets for chemical carcinogens?

    OpenAIRE

    Afshari, C A; Barrett, J C

    1993-01-01

    The progression of the cell cycle is controlled by the action of both positive and negative growth regulators. The key players in this activity include a family of cyclins and cyclin-dependent kinases, which are themselves regulated by other kinases and phosphatases. Maintenance of balanced cell cycle controls may be directly linked to genomic stability. Loss of the check-points involved in cell cycle control may result in unrepaired DNA damage during DNA synthesis or mitosis leading to genet...

  4. Extracellular adenosine controls NKT-cell-dependent hepatitis induction.

    Science.gov (United States)

    Subramanian, Meenakshi; Kini, Radhika; Madasu, Manasa; Ohta, Akiko; Nowak, Michael; Exley, Mark; Sitkovsky, Michail; Ohta, Akio

    2014-04-01

    Extracellular adenosine regulates inflammatory responses via the A2A adenosine receptor (A2AR). A2AR deficiency results in much exaggerated acute hepatitis, indicating nonredundancy of adenosine-A2AR pathway in inhibiting immune activation. To identify a critical target of immunoregulatory effect of extracellular adenosine, we focused on NKT cells, which play an indispensable role in hepatitis. An A2AR agonist abolished NKT-cell-dependent induction of acute hepatitis by concanavalin A (Con A) or α-galactosylceramide in mice, corresponding to downregulation of activation markers and cytokines in NKT cells and of NK-cell co-activation. These results show that A2AR signaling can downregulate NKT-cell activation and suppress NKT-cell-triggered inflammatory responses. Next, we hypothesized that NKT cells might be under physiological control of the adenosine-A2AR pathway. Indeed, both Con A and α-galactosylceramide induced more severe hepatitis in A2AR-deficient mice than in WT controls. Transfer of A2AR-deficient NKT cells into A2AR-expressing recipients resulted in exaggeration of Con A-induced liver damage, suggesting that NKT-cell activation is controlled by endogenous adenosine via A2AR, and this physiological regulatory mechanism of NKT cells is critical in the control of tissue-damaging inflammation. The current study suggests the possibility to manipulate NKT-cell activity in inflammatory disorders through intervention to the adenosine-A2AR pathway. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Preparation of size-controlled (30-100 nm) magnetite nanoparticles for biomedical applications

    International Nuclear Information System (INIS)

    Nishio, K.; Ikeda, M.; Gokon, N.; Tsubouchi, S.; Narimatsu, H.; Mochizuki, Y.; Sakamoto, S.; Sandhu, A.; Abe, M.; Handa, H.

    2007-01-01

    Size-controlled magnetite nanoparticles (MNPs) with several dozen nanometers (nm) were synthesized for biomedical applications. Nanoparticles of single-phase magnetite, as revealed by X-ray analyses and magnetic measurements, were prepared by oxidizing ferrous hydroxide (Fe(OH) 2 ) with a weak oxidant NaNO 3 in an N 2 -deaerated aqueous NaOH solution (pH=12-13) at various temperatures below 37 deg. C. As the synthesis temperature increases from 4 to 37 deg. C, the MNPs are decreased in size (d) from 102±5.6 to 31.7±4.9 nm and widened in size distribution, Δd/d increases from 5.5% to 15%. Prepared without using any surfactant, the MNPs are advantageous for immobilizing functional molecules stably on the surfaces for biomedical applications

  6. Monocrystalline solar cells performance coated by silver nanoparticles: Effect of NPs sizes from point of view Mie theory

    Science.gov (United States)

    Elnoby, Rasha M.; Mourad, M. Hussein; Elnaby, Salah L. Hassab; Abou Kana, Maram T. H.

    2018-05-01

    Solar based cells coated by nanoparticles (NPs) acknowledge potential utilizing as a part of photovoltaic innovation. The acquired silicon solar cells (Si-SCs) coated with different sizes of silver nanoparticles (Ag NPs) as well as uncoated were fabricated in our lab. The sizes and optical properties of prepared NPs were characterized by spectroscopic techniques and Mie theory respectively. The reflectivity of Si-SCs showed reduction of this property as the size of NPs increased. Electrical properties as open circuit current, fill factor and output power density were assessed and discussed depending on point of view of Mie theory for the optical properties of NPs. Also, photostabilities of SCs were assessed using diode laser of wavelength 450 nm and power 300 mW. Coated SCs with the largest Ag NPs size showed the highest Photostability due to its highest scattering efficiency according to Mie theory concept.

  7. Size-Controlled Production of Gold Bionanoparticles Using the Extremely Acidophilic Fe(III-Reducing Bacterium, Acidocella aromatica

    Directory of Open Access Journals (Sweden)

    Intan Nurul Rizki

    2018-02-01

    Full Text Available Recycling of gold-bearing “urban mine” resources, such as waste printed circuit boards (PCBs, is attracting an increasing interest. Some of the gold leaching techniques utilize acidic lixiviants and in order to eventually target such acidic leachates, the utility of the acidophilic Fe(III-reducing heterotrophic bacterium, Acidocella (Ac. aromatica PFBC was evaluated for production of Au(0 bionanoparticles (bio-AuNPs. Au(III ions (as AuCl4−, initially 10 mg/L, were readily adsorbed onto the slightly-positively charged Ac. aromatica cell surface and transported into cytoplasm to successfully form intracellular bio-AuNPs in a simple one-step microbiological reaction. Generally, increasing the initial concentration of formate as e-donor corresponded to faster Au(III bioreduction and a greater number of Au(0 nucleation sites with less crystal growth within 40–60 h: i.e., use of 1, 5, 10, or 20 mM formate led to production of bio-AuNPs of 48, 24, 13, or 12 nm in mean particle size with 2.3, 17, 62, and 97 particles/cell, respectively. Addition of Cu2+ as an enzymatic inhibitor significantly decreased the number of Au(0 nucleation sites but enhanced crystal growth of individual particles. As a result, the manipulation of the e-donor concentration combined with an enzyme inhibitor enabled the 3-grade size-control of bio-AuNPs (nearly within a normal distribution at 48, 26 or 13 nm by use of 1 mM formate, 20 mM formate (+Cu2+ or 10 mM formate, respectively, from highly acidic, dilute Au(III solutions.

  8. Rgs13 constrains early B cell responses and limits germinal center sizes.

    Directory of Open Access Journals (Sweden)

    Il-Young Hwang

    Full Text Available Germinal centers (GCs are microanatomic structures that develop in secondary lymphoid organs in response to antigenic stimulation. Within GCs B cells clonally expand and their immunoglobulin genes undergo class switch recombination and somatic hypermutation. Transcriptional profiling has identified a number of genes that are prominently expressed in GC B cells. Among them is Rgs13, which encodes an RGS protein with a dual function. Its canonical function is to accelerate the intrinsic GTPase activity of heterotrimeric G-protein α subunits at the plasma membrane, thereby limiting heterotrimeric G-protein signaling. A unique, non-canonical function of RGS13 occurs following translocation to the nucleus, where it represses CREB transcriptional activity. The functional role of RGS13 in GC B cells is unknown. To create a surrogate marker for Rgs13 expression and a loss of function mutation, we inserted a GFP coding region into the Rgs13 genomic locus. Following immunization GFP expression rapidly increased in activated B cells, persisted in GC B cells, but declined in newly generated memory B and plasma cells. Intravital microscopy of the inguinal lymph node (LN of immunized mice revealed the rapid appearance of GFP(+ cells at LN interfollicular regions and along the T/B cell borders, and eventually within GCs. Analysis of WT, knock-in, and mixed chimeric mice indicated that RGS13 constrains extra-follicular plasma cell generation, GC size, and GC B cell numbers. Analysis of select cell cycle and GC specific genes disclosed an aberrant gene expression profile in the Rgs13 deficient GC B cells. These results indicate that RGS13, likely acting at cell membranes and in nuclei, helps coordinate key decision points during the expansion and differentiation of naive B cells.

  9. Rgs13 constrains early B cell responses and limits germinal center sizes.

    Science.gov (United States)

    Hwang, Il-Young; Hwang, Kyung-Sun; Park, Chung; Harrison, Kathleen A; Kehrl, John H

    2013-01-01

    Germinal centers (GCs) are microanatomic structures that develop in secondary lymphoid organs in response to antigenic stimulation. Within GCs B cells clonally expand and their immunoglobulin genes undergo class switch recombination and somatic hypermutation. Transcriptional profiling has identified a number of genes that are prominently expressed in GC B cells. Among them is Rgs13, which encodes an RGS protein with a dual function. Its canonical function is to accelerate the intrinsic GTPase activity of heterotrimeric G-protein α subunits at the plasma membrane, thereby limiting heterotrimeric G-protein signaling. A unique, non-canonical function of RGS13 occurs following translocation to the nucleus, where it represses CREB transcriptional activity. The functional role of RGS13 in GC B cells is unknown. To create a surrogate marker for Rgs13 expression and a loss of function mutation, we inserted a GFP coding region into the Rgs13 genomic locus. Following immunization GFP expression rapidly increased in activated B cells, persisted in GC B cells, but declined in newly generated memory B and plasma cells. Intravital microscopy of the inguinal lymph node (LN) of immunized mice revealed the rapid appearance of GFP(+) cells at LN interfollicular regions and along the T/B cell borders, and eventually within GCs. Analysis of WT, knock-in, and mixed chimeric mice indicated that RGS13 constrains extra-follicular plasma cell generation, GC size, and GC B cell numbers. Analysis of select cell cycle and GC specific genes disclosed an aberrant gene expression profile in the Rgs13 deficient GC B cells. These results indicate that RGS13, likely acting at cell membranes and in nuclei, helps coordinate key decision points during the expansion and differentiation of naive B cells.

  10. Charge-Control Unit for Testing Lithium-Ion Cells

    Science.gov (United States)

    Reid, Concha M.; Mazo, Michelle A.; Button, Robert M.

    2008-01-01

    A charge-control unit was developed as part of a program to validate Li-ion cells packaged together in batteries for aerospace use. The lithium-ion cell charge-control unit will be useful to anyone who performs testing of battery cells for aerospace and non-aerospace uses and to anyone who manufacturers battery test equipment. This technology reduces the quantity of costly power supplies and independent channels that are needed for test programs in which multiple cells are tested. Battery test equipment manufacturers can integrate the technology into their battery test equipment as a method to manage charging of multiple cells in series. The unit manages a complex scheme that is required for charging Li-ion cells electrically connected in series. The unit makes it possible to evaluate cells together as a pack using a single primary test channel, while also making it possible to charge each cell individually. Hence, inherent cell-to-cell variations in a series string of cells can be addressed, and yet the cost of testing is reduced substantially below the cost of testing each cell as a separate entity. The unit consists of electronic circuits and thermal-management devices housed in a common package. It also includes isolated annunciators to signal when the cells are being actively bypassed. These annunciators can be used by external charge managers or can be connected in series to signal that all cells have reached maximum charge. The charge-control circuitry for each cell amounts to regulator circuitry and is powered by that cell, eliminating the need for an external power source or controller. A 110-VAC source of electricity is required to power the thermal-management portion of the unit. A small direct-current source can be used to supply power for an annunciator signal, if desired.

  11. Robust SMES controller design for stabilization of inter-area oscillation considering coil size and system uncertainties

    International Nuclear Information System (INIS)

    Ngamroo, Issarachai

    2010-01-01

    It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size.

  12. Robust SMES controller design for stabilization of inter-area oscillation considering coil size and system uncertainties

    Science.gov (United States)

    Ngamroo, Issarachai

    2010-12-01

    It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size.

  13. Large body size and sedentary lifestyle during childhood and early adulthood and esophageal squamous cell carcinoma in a high-risk population.

    Science.gov (United States)

    Etemadi, A; Golozar, A; Kamangar, F; Freedman, N D; Shakeri, R; Matthews, C; Islami, F; Boffetta, P; Brennan, P; Abnet, C C; Malekzadeh, R; Dawsey, S M

    2012-06-01

    Little is known about the association of obesity and physical activity at young ages with subsequent risk of esophageal squamous cell carcinoma (ESCC). Between 2003 and 2007, we conducted a case-control study in a high-risk population in northeastern Iran. Three hundred ESCC cases and 571 matched controls were recruited. Each individual was shown a standard pictogram, to report body size at ages 15 and 30. Demographic and health-related information, including physical activity at these ages was also collected. In the fully adjusted models, very obese body size (last two pictograms) at age 15 [odds ratio (OR) 3.2, 95% confidence interval (CI) 1.3-7.7] and age 30 (OR 3.1; 95% CI 1.1-8.5) were associated with ESCC in women, but not in men. Sedentary work at age 15 (OR 3.3, 95% CI 1.3-8.3) and 30 (OR 18.2, 95% CI 3.9-86.2) were also associated with ESCC risk in women only. The increased risk in women at age 15 remained high after later reduction in body size, while women who became very obese only at age 30 did not show a significantly increased risk. These results highlight the importance of early lifestyle modifications in the context of cancer prevention, particularly in women.

  14. [Role of medium-sized independent laboratories in control of healthcare-associated infection].

    Science.gov (United States)

    Anzai, Eiko; Fukui, Toru

    2009-05-01

    In 2006, the Ministry of Health and Welfare revised the regulations regarding the Medical Service Law. The amendments stipulate that all healthcare institutions are required to implement infection control programs. However, small hospitals and clinics have no clinical microbiology laboratories, whereas medium-sized hospitals have few medical technologists and the outsourcing of microbiology tests to independent laboratories is common. The decreasing number of laboratories and recent outsourcing tendency reflect the increasing commercialization, and, with it, the escalating number of commercially operating chains. Each independent laboratory is responsible for supporting activities related to the surveillance, control, and prevention of healthcare-associated infections in the associated small and medium-sized hospitals. The people responsible for infection control in these hospitals usually do not have a background in microbiology. The evaluation of communication between independent laboratory staff and hospital personnel, and rapid turnaround time of microbiology laboratory test reports are important elements ensuring the quality of independent laboratory work. With the pressures of financial constraints in the Japanese medical insurance system, the development of a cost-effective and practical protocol for quality assurance is a real dilemma.

  15. Fuel cell generator with fuel electrodes that control on-cell fuel reformation

    Science.gov (United States)

    Ruka, Roswell J [Pittsburgh, PA; Basel, Richard A [Pittsburgh, PA; Zhang, Gong [Murrysville, PA

    2011-10-25

    A fuel cell for a fuel cell generator including a housing including a gas flow path for receiving a fuel from a fuel source and directing the fuel across the fuel cell. The fuel cell includes an elongate member including opposing first and second ends and defining an interior cathode portion and an exterior anode portion. The interior cathode portion includes an electrode in contact with an oxidant flow path. The exterior anode portion includes an electrode in contact with the fuel in the gas flow path. The anode portion includes a catalyst material for effecting fuel reformation along the fuel cell between the opposing ends. A fuel reformation control layer is applied over the catalyst material for reducing a rate of fuel reformation on the fuel cell. The control layer effects a variable reformation rate along the length of the fuel cell.

  16. Investigation of Low-Cost Surface Processing Techniques for Large-Size Multicrystalline Silicon Solar Cells

    OpenAIRE

    Cheng, Yuang-Tung; Ho, Jyh-Jier; Lee, William J.; Tsai, Song-Yeu; Lu, Yung-An; Liou, Jia-Jhe; Chang, Shun-Hsyung; Wang, Kang L.

    2010-01-01

    The subject of the present work is to develop a simple and effective method of enhancing conversion efficiency in large-size solar cells using multicrystalline silicon (mc-Si) wafer. In this work, industrial-type mc-Si solar cells with area of 125×125 mm2 were acid etched to produce simultaneously POCl3 emitters and silicon nitride deposition by plasma-enhanced chemical vapor deposited (PECVD). The study of surface morphology and reflectivity of different mc-Si etched surfaces has also been d...

  17. Chemo-mechanical control of neural stem cell differentiation

    Science.gov (United States)

    Geishecker, Emily R.

    Cellular processes such as adhesion, proliferation, and differentiation are controlled in part by cell interactions with the microenvironment. Cells can sense and respond to a variety of stimuli, including soluble and insoluble factors (such as proteins and small molecules) and externally applied mechanical stresses. Mechanical properties of the environment, such as substrate stiffness, have also been suggested to play an important role in cell processes. The roles of both biochemical and mechanical signaling in fate modification of stem cells have been explored independently. However, very few studies have been performed to study well-controlled chemo-mechanotransduction. The objective of this work is to design, synthesize, and characterize a chemo-mechanical substrate to encourage neuronal differentiation of C17.2 neural stem cells. In Chapter 2, Polyacrylamide (PA) gels of varying stiffnesses are functionalized with differing amounts of whole collagen to investigate the role of protein concentration in combination with substrate stiffness. As expected, neurons on the softest substrate were more in number and neuronal morphology than those on stiffer substrates. Neurons appeared locally aligned with an expansive network of neurites. Additional experiments would allow for statistical analysis to determine if and how collagen density impacts C17.2 differentiation in combination with substrate stiffness. Due to difficulties associated with whole protein approaches, a similar platform was developed using mixed adhesive peptides, derived from fibronectin and laminin, and is presented in Chapter 3. The matrix elasticity and peptide concentration can be individually modulated to systematically probe the effects of chemo-mechanical signaling on differentiation of C17.2 cells. Polyacrylamide gel stiffness was confirmed using rheological techniques and found to support values published by Yeung et al. [1]. Cellular growth and differentiation were assessed by cell counts

  18. Lithium-Ion Cell Charge-Control Unit Developed

    Science.gov (United States)

    Reid, Concha M.; Manzo, Michelle A.; Buton, Robert M.; Gemeiner, Russel

    2005-01-01

    A lithium-ion (Li-ion) cell charge-control unit was developed as part of a Li-ion cell verification program. This unit manages the complex charging scheme that is required when Li-ion cells are charged in series. It enables researchers to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and reduces test costs substantially in comparison to individual cell testing.

  19. Electrokinetic and optical control of bacterial microrobots

    International Nuclear Information System (INIS)

    Steager, Edward B; Kim, Dal Hyung; Kim, Min Jun; Sakar, Mahmut Selman; Kumar, Vijay; Pappas, George J

    2011-01-01

    One of the great challenges in microscale science and engineering is the independent manipulation of cells and man-made objects on the micron scale. For such work, motile microorganisms are integrated with engineered systems to construct microbiorobots (MBRs). MBRs are negative photosensitive epoxy (SU-8) microfabricated structures with typical feature sizes ranging from 1 to 100 µm coated with a monolayer of swarmer cells of the bacterium Serratia marcescens. The adherent cells naturally coordinate to propel the microstructures in fluidic environments. In this study, ultraviolet light is used to control rotational motion and direct current electric fields are used to control the two-dimensional movement of MBRs. They are steered in a fully automated fashion using computer-controlled visual servoing, used to transport and manipulate micron-sized objects, and employed as cell-based biosensors. This work is a step toward in vitro mechanical or chemical manipulation of cells as well as controlled assembly of microcomponents.

  20. Nanostructured titanium dioxide: a control of crystallite size and content of polymorphic phases

    International Nuclear Information System (INIS)

    Boery, Mirella N. de O.; Ono, Eduardo; Manfrim, Tarcio P.; Santos, Juliana S.; Suzuki, Carlos K.

    2010-01-01

    TiO 2 (titanium dioxide) powders and nanoparticles have been largely used in toners and cosmetics. Nowadays, they are mainly focused in photocatalysis, antibacterial coatings, dye-sensitized solar cells, etc. The efficiency is related to photocatalytic properties of TiO 2 nanoparticles, such as crystallite size and phase (anatasio/rutile). In this research, flame aerosol method was used to synthesize TiO 2 nanoparticles by hydrolysis and oxidation of TiCl 4 (titanium tetrachloride). The oxy-hydrogen flame was provided by a five concentric nozzle silica burner. X-ray diffraction was used to identify each TiO 2 nanoparticles phase and scanning electron microscopy was used to observe the size and morphology of nanoparticles. Pure anatase was obtained with H 2 /O 2 ratio ≤ 1.0, and up to 52 wt% of rutile was obtained with H 2 /O 2 ratio > 2.0. Anatase crystal grain size varied from 25 to 38 nm, estimated by Scherrer formula.(author)

  1. Effect of size of bioactive glass nanoparticles on mesenchymal stem cell proliferation for dental and orthopedic applications

    International Nuclear Information System (INIS)

    Ajita, J.; Saravanan, S.; Selvamurugan, N.

    2015-01-01

    Bioactive glass nanoparticles (nanostructured bioglass ceramics or nBGs) have been widely employed as a filler material for bone tissue regeneration. The physical properties of nBG particles govern their biological actions. In this study, the impact of the size of nBG particles on mouse mesenchymal stem cell (mMSC) proliferation was investigated. Three different sizes of nBG particles were prepared via the sol–gel method with varying concentrations of the surfactant and polyethylene glycol (PEG), and the particles were characterized. Increased concentrations of PEG decreased the size of nBG particles (nBG-1: 74.7 ± 0.62 nm, nBG-2: 43.25 ± 1.5 nm, and nBG-3: 37.6 ± 0.81 nm). All three nBGs were non-toxic at a concentration of 20 mg/mL. Increased proliferation was observed in mMSCs treated with smaller nBG particles. Differential mRNA expression of cyclin A2, B2, D1, and E1 genes induced by nBG particles was noticed in the mMSCs. nBG-1 and nBG-3 particles promoted cells in the G0/G1 phase to enter the S and G2/M phases. nBG particles activated ERK, but prolonged activation was achieved with nBG-3 particles. Among the prepared nBG particles, nBG-3 particles showed enhanced mMSC proliferation via the sustained activation of ERKs, upregulation of cyclin gene(s) expression, and promotion of cell transition from the G0/G1 phase to the S and G2/M phases. Thus, this study indicates that small nBG particles have clinical applications in dental and bone treatments as fillers or bone-tissue bond forming materials. - Highlights: • Three different sizes of bioactive glass nanoparticles (nBGs) were prepared via the sol–gel method. • Increased concentrations of polyethylene glycol decreased the size of nBG particles. • All three nBGs were non-toxic at a concentration of 20 mg/mL. • Cell number, cell cycle phase analysis, cyclin gene expression and ERK activation were studied. • Increased proliferation was observed in mMSCs treated with smaller nBG particles

  2. Size matters: insights from an allometric approach to evaluate control methods for invasive Australian Rhinella marina.

    Science.gov (United States)

    Beaty, Lynne E; Salice, Christopher J

    2013-10-01

    Invasive species are costly and difficult to control. In order to gain a mechanistic understanding of potential control measures, individual-based models uniquely parameterized to reflect the salient life-history characteristics of invasive species are useful. Using invasive Australian Rhinella marina as a case study, we constructed a cohort- and individual-based population simulation that incorporates growth and body size of terrestrial stages. We used this allometric approach to examine the efficacy of nontraditional control methods (i.e., tadpole alarm chemicals and native meat ants) that may have indirect effects on population dynamics mediated by effects on body size. We compared population estimates resulting from these control methods with traditional hand removal. We also conducted a sensitivity analysis to investigate the effect that model parameters, specifically those associated with growth and body size, had on adult population estimates. Incremental increases in hand removal of adults and juveniles caused nonlinear decreases in adult population estimates, suggesting less return with increased investment in hand-removal efforts. Applying tadpole alarm chemicals or meat ants decreased adult population estimates on the same level as removing 15-25% of adults and juveniles by hand. The combined application of tadpole alarm chemicals and meat ants resulted in approximately 80% decrease in adult abundance, the largest of any applied control method. In further support of the nontraditional control methods, which greatly affected the metamorph stage, our model was most sensitive to changes in metamorph survival, juvenile survival, metamorph growth rate, and adult survival. Our results highlight the use and insights that can be gained from individual-based models that incorporate growth and body size and the potential success that nontraditional control methods could have in controlling established, invasive Rhinella marina populations.

  3. A Short-Term Advantage for Syngamy in the Origin of Eukaryotic Sex: Effects of Cell Fusion on Cell Cycle Duration and Other Effects Related to the Duration of the Cell Cycle-Relationship between Cell Growth Curve and the Optimal Size of the Species, and Circadian Cell Cycle in Photosynthetic Unicellular Organisms.

    Science.gov (United States)

    Mancebo Quintana, J M; Mancebo Quintana, S

    2012-01-01

    The origin of sex is becoming a vexatious issue for Evolutionary Biology. Numerous hypotheses have been proposed, based on the genetic effects of sex, on trophic effects or on the formation of cysts and syncytia. Our approach addresses the change in cell cycle duration which would cause cell fusion. Several results are obtained through graphical and mathematical analysis and computer simulations. (1) In poor environments, cell fusion would be an advantageous strategy, as fusion between cells of different size shortens the cycle of the smaller cell (relative to the asexual cycle), and the majority of mergers would occur between cells of different sizes. (2) The easiest-to-evolve regulation of cell proliferation (sexual/asexual) would be by modifying the checkpoints of the cell cycle. (3) A regulation of this kind would have required the existence of the G2 phase, and sex could thus be the cause of the appearance of this phase. Regarding cell cycle, (4) the exponential curve is the only cell growth curve that has no effect on the optimal cell size in unicellular species; (5) the existence of a plateau with no growth at the end of the cell cycle explains the circadian cell cycle observed in unicellular algae.

  4. A Short-Term Advantage for Syngamy in the Origin of Eukaryotic Sex: Effects of Cell Fusion on Cell Cycle Duration and Other Effects Related to the Duration of the Cell Cycle—Relationship between Cell Growth Curve and the Optimal Size of the Species, and Circadian Cell Cycle in Photosynthetic Unicellular Organisms

    Science.gov (United States)

    Mancebo Quintana, J. M.; Mancebo Quintana, S.

    2012-01-01

    The origin of sex is becoming a vexatious issue for Evolutionary Biology. Numerous hypotheses have been proposed, based on the genetic effects of sex, on trophic effects or on the formation of cysts and syncytia. Our approach addresses the change in cell cycle duration which would cause cell fusion. Several results are obtained through graphical and mathematical analysis and computer simulations. (1) In poor environments, cell fusion would be an advantageous strategy, as fusion between cells of different size shortens the cycle of the smaller cell (relative to the asexual cycle), and the majority of mergers would occur between cells of different sizes. (2) The easiest-to-evolve regulation of cell proliferation (sexual/asexual) would be by modifying the checkpoints of the cell cycle. (3) A regulation of this kind would have required the existence of the G2 phase, and sex could thus be the cause of the appearance of this phase. Regarding cell cycle, (4) the exponential curve is the only cell growth curve that has no effect on the optimal cell size in unicellular species; (5) the existence of a plateau with no growth at the end of the cell cycle explains the circadian cell cycle observed in unicellular algae. PMID:22666626

  5. PortionControl@HOME: Results of a Randomized Controlled Trial Evaluating the Effect of a Multi-Component Portion Size Intervention on Portion Control Behavior and Body Mass Index

    NARCIS (Netherlands)

    Poelman, M.P.; Vet, de E.; Velema, E.; Boer, de M.R.; Seidell, J.C.; Steenhuis, I.H.M.

    2015-01-01

    Background Food portion sizes influence energy intake. Purpose The purpose of this paper is to determine effectiveness of the “PortionControl@HOME” intervention on body mass index and portion control behavior. Methods A randomized controlled trial among 278 overweight and obese participants was

  6. Automatic Control of Gene Expression in Mammalian Cells.

    Science.gov (United States)

    Fracassi, Chiara; Postiglione, Lorena; Fiore, Gianfranco; di Bernardo, Diego

    2016-04-15

    Automatic control of gene expression in living cells is paramount importance to characterize both endogenous gene regulatory networks and synthetic circuits. In addition, such a technology can be used to maintain the expression of synthetic circuit components in an optimal range in order to ensure reliable performance. Here we present a microfluidics-based method to automatically control gene expression from the tetracycline-inducible promoter in mammalian cells in real time. Our approach is based on the negative-feedback control engineering paradigm. We validated our method in a monoclonal population of cells constitutively expressing a fluorescent reporter protein (d2EYFP) downstream of a minimal CMV promoter with seven tet-responsive operator motifs (CMV-TET). These cells also constitutively express the tetracycline transactivator protein (tTA). In cells grown in standard growth medium, tTA is able to bind the CMV-TET promoter, causing d2EYFP to be maximally expressed. Upon addition of tetracycline to the culture medium, tTA detaches from the CMV-TET promoter, thus preventing d2EYFP expression. We tested two different model-independent control algorithms (relay and proportional-integral (PI)) to force a monoclonal population of cells to express an intermediate level of d2EYFP equal to 50% of its maximum expression level for up to 3500 min. The control input is either tetracycline-rich or standard growth medium. We demonstrated that both the relay and PI controllers can regulate gene expression at the desired level, despite oscillations (dampened in the case of the PI controller) around the chosen set point.

  7. Neural network control of focal position during time-lapse microscopy of cells.

    Science.gov (United States)

    Wei, Ling; Roberts, Elijah

    2018-05-09

    Live-cell microscopy is quickly becoming an indispensable technique for studying the dynamics of cellular processes. Maintaining the specimen in focus during image acquisition is crucial for high-throughput applications, especially for long experiments or when a large sample is being continuously scanned. Automated focus control methods are often expensive, imperfect, or ill-adapted to a specific application and are a bottleneck for widespread adoption of high-throughput, live-cell imaging. Here, we demonstrate a neural network approach for automatically maintaining focus during bright-field microscopy. Z-stacks of yeast cells growing in a microfluidic device were collected and used to train a convolutional neural network to classify images according to their z-position. We studied the effect on prediction accuracy of the various hyperparameters of the neural network, including downsampling, batch size, and z-bin resolution. The network was able to predict the z-position of an image with ±1 μm accuracy, outperforming human annotators. Finally, we used our neural network to control microscope focus in real-time during a 24 hour growth experiment. The method robustly maintained the correct focal position compensating for 40 μm of focal drift and was insensitive to changes in the field of view. About ~100 annotated z-stacks were required to train the network making our method quite practical for custom autofocus applications.

  8. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Science.gov (United States)

    Sonmez, Melda; Ince, Huseyin Yavuz; Yalcin, Ozlem; Ajdžanović, Vladimir; Spasojević, Ivan; Meiselman, Herbert J; Baskurt, Oguz K

    2013-01-01

    The role of membrane fluidity in determining red blood cell (RBC) deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol) using ektacytometry and electron paramagnetic resonance (EPR) spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease) and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; palcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology) was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  9. Models and simulations for the Danish cell project. Running PowerFactory with OPC and cell controller

    Energy Technology Data Exchange (ETDEWEB)

    Martensen, Nis; Troester, Eckehard [energynautics GmbH, Langen (Germany); Lund, Per [Energinet.dk, Fredericia (Denmark); Holland, Rod [Spirae Inc., Fort Collins, CO (United States)

    2009-07-01

    In emergency situations, the Cell Controller disconnects a distribution grid from the high-voltage network and controls the cell's island operation. The controller thus activates the existing local generation plants to improve the security of supply. The Cell Controller can operate the Cell as a Virtual Power Plant during normal grid-connected operation, thereby implementing an exemplary Smart Grid. Modeling and simulation work is presented. (orig.)

  10. Photochemical fabrication of size-controllable gold nanoparticles on chitosan and their application on catalytic decomposition of acetaldehyde

    International Nuclear Information System (INIS)

    Yu, Chung-Chin; Yang, Kuang-Hsuan; Liu, Yu-Chuan; Chen, Bo-Chuen

    2010-01-01

    In this work, we report a new pathway to prepare size-controllable gold nanoparticles (NPs) on chitosan (Ch) in aqueous solutions for improving catalytic decomposition of acetaldehyde by pure gold NPs at room temperature. First, Au substrates were cycled in deoxygenated aqueous solutions containing 0.1N NaCl and 1 g/L Ch from -0.28 to +1.22 V vs Ag/AgCl at 500 mV/s for 200 scans. Then the solutions were irradiated with UV lights of different wavelengths to prepare size-controllable Au NPs on Ch. Experimental results indicate that the particle sizes of prepared NPs are increased when UV lights with longer wavelengths were employed. The particle sizes of resulted Au NPs can be controlled from 10 to 50 nm. Moreover, the decomposition of acetaldehydes in wines can be significantly enhanced by ca. 190% of magnitude due to the contribution of the adsorption of Au NPs on Ch.

  11. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    Directory of Open Access Journals (Sweden)

    David Veale, MD, FRCPsych

    2015-09-01

    Conclusion: Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures. Veale D, Miles S, Read J, Troglia A, Wylie K, and Muir G. Sexual functioning and behavior of men with body dysmorphic disorder concerning penis size compared with men anxious about penis size and with controls: A cohort study. Sex Med 2015;3:147–155.

  12. Improving enrichment of circulating fetal DNA for genetic testing: size fractionation followed by whole gene amplification.

    Science.gov (United States)

    Jorgez, Carolina J; Bischoff, Farideh Z

    2009-01-01

    Among the pitfalls of using cell-free fetal DNA in plasma for prenatal diagnosis is quality of the recovered DNA fragments and concomitant presence of maternal DNA (>95%). Our objective is to provide alternative methods for achieving enrichment and high-quality fetal DNA from plasma. Cell-free DNA from 31 pregnant women and 18 controls (10 males and 8 females) were size separated using agarose gel electrophoresis. DNA fragments of 100-300, 500-700 and 1,500-2,000 bp were excised and extracted, followed by whole genome amplification (WGA) of recovered fragments. Levels of beta-globin and DYS1 were measured. Distribution of beta-globin size fragments was similar among pregnant women and controls. Among control male cases, distribution of size fragments was the same for both beta-globin and DYS1. Among maternal cases confirmed to be male, the smallest size fragment (100-300 bp) accounted for nearly 50% (39.76 +/- 17.55%) of the recovered DYS1-DNA (fetal) and only 10% (10.40 +/- 6.49%) of beta-globin (total) DNA. After WGA of plasma fragments from pregnant women, DYS1 sequence amplification was best observed when using the 100-300 bp fragments as template. Combination of electrophoresis for size separation and WGA led to enriched fetal DNA from plasma. This novel combination of strategies is more likely to permit universal clinical applications of cell-free fetal DNA. Copyright 2009 S. Karger AG, Basel.

  13. Excellent endurance of MWCNT anode in micro-sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.; Hussain, Muhammad Mustafa

    2012-01-01

    Microbial Fuel Cells (MFCs) are a sustainable technology for energy production using bioelectrochemical reactions from bacteria. Microfabrication of micro-sized MFCs allows rapid and precise production of devices that can be integrated into Lab-on-a-chip or other ultra low power devices. We show a multi-walled carbon nanotubes (MWCNTs) integrated anode in a biocompatible and high power and current producing device. Long term testing of the MWCNT anode also reveals a high endurance and durable anode material that can be adapted as a long-lasting power source. © 2012 IEEE.

  14. Excellent endurance of MWCNT anode in micro-sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.

    2012-08-01

    Microbial Fuel Cells (MFCs) are a sustainable technology for energy production using bioelectrochemical reactions from bacteria. Microfabrication of micro-sized MFCs allows rapid and precise production of devices that can be integrated into Lab-on-a-chip or other ultra low power devices. We show a multi-walled carbon nanotubes (MWCNTs) integrated anode in a biocompatible and high power and current producing device. Long term testing of the MWCNT anode also reveals a high endurance and durable anode material that can be adapted as a long-lasting power source. © 2012 IEEE.

  15. Ectopic expression of human mTOR increases viability, robustness, cell size, proliferation, and antibody production of chinese hamster ovary cells.

    Science.gov (United States)

    Dreesen, Imke A J; Fussenegger, Martin

    2011-04-01

    Engineering of mammalian production cell lines to improve titer and quality of biopharmaceuticals is a top priority of the biopharmaceutical manufacturing industry providing protein therapeutics to patients worldwide. While many engineering strategies have been successful in the past decade they were often based on the over-expression of a single transgene and therefore limited to addressing a single bottleneck in the cell's production capacity. We provide evidence that ectopic expression of the global metabolic sensor and processing protein mammalian target of rapamycin (mTOR), simultaneously improves key bioprocess-relevant characteristics of Chinese hamster ovary (CHO) cell-derived production cell lines such as cell growth (increased cell size and protein content), proliferation (increased cell-cycle progression), viability (decreased apoptosis), robustness (decreased sensitivity to sub-optimal growth factor and oxygen supplies) and specific productivity of secreted human glycoproteins. Cultivation of mTOR-transgenic CHO-derived cell lines engineered for secretion of a therapeutic IgG resulted in antibody titers of up to 50 pg/cell/day, which represents a four-fold increase compared to the parental production cell line. mTOR-based engineering of mammalian production cell lines may therefore have a promising future in biopharmaceutical manufacturing of human therapeutic proteins. Copyright © 2010 Wiley Periodicals, Inc.

  16. An optimal control problem for controlling the cell volume in dehydration and rehydration process

    Energy Technology Data Exchange (ETDEWEB)

    Chenghung Huang; Tetsung Chen [National Cheng Kung Univ., Dept. of Systems and Naval Mechatronic Engineering, Tainan (Taiwan)

    2004-08-01

    An optimal control algorithm utilizing the conjugate gradient method (CGM) of minimization is applied successfully in the present study in determining the optimal boundary control function for a diffusion-limited cell model based on the desired cell volume. The validity of the present optimal control analysis is examined by means of numerical experiments. Different desired cell volume for dehydration, rehydration and their combination are given in three test cases with different weighting coefficients and the corresponding optimal control functions are determined. The results show that the optimal boundary control functions can be obtained with an arbitrary initial guess within one second CPU time on a Pentium III-600 MHz PC. (Author)

  17. Seed-mediated growth and manipulation of Au nanorods via size-controlled synthesis of Au seeds

    International Nuclear Information System (INIS)

    Liu Juncheng; Duggan, Jennifer N.; Morgan, Joshua; Roberts, Christopher B.

    2012-01-01

    Seed-mediated growth of gold (Au) nanorods with highly controllable length, width, and aspect ratio was accomplished via carefully size-controlled synthesis of the original Au seeds. A slow dynamic growth of Au nanoparticle seeds was observed after reduction of the Au salt (i.e., hydrogen tetrachloroaurate (III) hydrate) by sodium borohydride (NaBH 4 ) in the presence of cetyltrimethyl ammonium bromide (CTAB). As such, the size of the Au nanoparticle seeds can therefore be manipulated through control over the duration of the reaction period (i.e., aging times of 2, 8, 48, 72, and 144 h were used in this study). These differently sized Au nanoparticles were subsequently used as seeds for the growth of Au nanorods, where the additions of Au salt, CTAB, AgNO 3 , and ascorbic acid were employed. Smaller Au nanoparticle seeds obtained via short growth/aging time resulted in Au nanorods with higher aspect ratio and thus longer longitudinal surface plasmon wavelength (LSPW). The larger Au nanoparticle seeds obtained via longer growth/aging time resulted in Au nanorods with lower aspect ratio and shorter LSPW.

  18. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

    Science.gov (United States)

    Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

    2015-08-01

    (ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures. Electronic supplementary information (ESI) available: Materials and experimental methods for the synthesis of (1) positively charged alkyne functionalized nanoparticles (2) Zn(ii) and Cu(ii) centred porphyrin (3); conjugating porphyrins to alkyne-functionalized nanoparticles via click chemistry (4) nanoparticle characterisation (size charge and fluorescence), (5) synthesis of BPTFMC (6) hMSC collection, storage and preparation (7) delivery of porphyrin functionalized nanoparticles (8) staining mitochondria, cumulative ROS production and determination of nanoparticles subcellular localisation (9) fluorescence microscopy and controlled irradiation of hMSCs (10) flow cytometry and controlled irradiation using a custom built irradiator. In addition, results highlighting: (1) nanoparticles emission spectra, size and charge, (2) BPTFMC fluorescence response and (3) hMSCs following light irradiation using flow cytometry. See DOI: 10.1039/c5nr00795j

  19. Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions.

    Science.gov (United States)

    Kaji, Hirokazu; Camci-Unal, Gulden; Langer, Robert; Khademhosseini, Ali

    2011-03-01

    Inside the body, cells lie in direct contact or in close proximity to other cell types in a tightly controlled architecture that often regulates the resulting tissue function. Therefore, tissue engineering constructs that aim to reproduce the architecture and the geometry of tissues will benefit from methods of controlling cell-cell interactions with microscale resolution. We discuss the use of microfabrication technologies for generating patterned co-cultures. In addition, we categorize patterned co-culture systems by cell type and discuss the implications of regulating cell-cell interactions in the resulting biological function of the tissues. Patterned co-cultures are a useful tool for fabricating tissue engineered constructs and for studying cell-cell interactions in vitro, because they can be used to control the degree of homotypic and heterotypic cell-cell contact. In addition, this approach can be manipulated to elucidate important factors involved in cell-matrix interactions. Patterned co-culture strategies hold significant potential to develop biomimetic structures for tissue engineering. It is expected that they would create opportunities to develop artificial tissues in the future. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine. 2010 Elsevier B.V. All rights reserved.

  20. Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate

    Directory of Open Access Journals (Sweden)

    Li F

    2017-11-01

    Full Text Available Feng Li,1 Yan Chen,1,2 Shubo Liu,1 Jian Qi,1 Weiying Wang,1 Chenhua Wang,1 Ruiyue Zhong,1 Zhijun Chen,1 Xiaoming Li,1 Yuanzhou Guan,1 Wei Kong,1,2 Yong Zhang1,2 1National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 2Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, China Abstract: Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed. Keywords: zein, phase separation, microparticle, nanoparticle, encapsulation

  1. Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Che Azurahanim Che; Asanithi, Piyapong; Brunner, Eric W; Jurewicz, Izabela; Bo, Chiara; Sear, Richard P; Dalton, Alan B [Department of Physics and Surrey Materials Institute, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Azad, Chihye Lewis; Ovalle-Robles, Raquel; Fang Shaoli; Lima, Marcio D; Lepro, Xavier; Collins, Steve; Baughman, Ray H, E-mail: r.sear@surrey.ac.uk [Alan G MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080-3021 (United States)

    2011-05-20

    Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.

  2. Advances on development of suction and temperature controlled oedometer cell

    International Nuclear Information System (INIS)

    Ye Weimin; Zhang Yawei; Chen Bao; Wang Min

    2010-01-01

    Oedometer cells for unsaturated soils can be classified into two types, that is, conventional unsaturated oedometer cells (high-suction unsaturated oedometer cell, high-suction and high-pressure unsaturated oedometer cell) and temperature controlled unsaturated oedometer cells. Among them, the osmotic, vapor equilibrium and axis translation techniques are often employed for suction control. The thermostat bath method and thermostatically controlled heater method are commonly used for temperature control. The lever loading system, hydraulic loading system and air pressure loading system are commonly means used for vertical pressure. Combination of osmotic (or axis translation) technique with vapor equilibrium method employed for the full range suction control, thermostatically liquid temperature control method, and the hydraulic loading system, could be used for suction, temperature and loading control in the design for unsaturated oedometer cells in the future, which can be used for study of buffer/backfill materials under high-temperature, high pressure and full range suction conditions. (authors)

  3. Mesenchymal stem cells-seeded bio-ceramic construct for bone regeneration in large critical-size bone defect in rabbit

    Directory of Open Access Journals (Sweden)

    Maiti SK

    2016-11-01

    Full Text Available Bone marrow derived mesenchymal stem cells (BMSC represent an attractive cell population for tissue engineering purpose. The objective of this study was to determine whether the addition of recombinant human bone morphogenetic protein (rhBMP-2 and insulin-like growth factor (IGF-1 to a silica-coated calcium hydroxyapatite (HASi - rabbit bone marrow derived mesenchymal stem cell (rBMSC construct promoted bone healing in a large segmental bone defect beyond standard critical -size radial defects (15mm in rabbits. An extensively large 30mm long radial ostectomy was performed unilaterally in thirty rabbits divided equally in five groups. Defects were filled with a HASi scaffold only (group B; HASi scaffold seeded with rBMSC (group C; HASi scaffold seeded with rBMSC along with rhBMP-2 and IGF-1 in groups D and E respectively. The same number of rBMSC (five million cells and concentration of growth factors rhBMP-2 (50µg and IGF-1 (50µg was again injected at the site of bone defect after 15 days of surgery in their respective groups. An empty defect served as the control group (group A. Radiographically, bone healing was evaluated at 7, 15, 30, 45, 60 and 90 days post implantation. Histological qualitative analysis with microCT (µ-CT, haematoxylin and eosin (H & E and Masson’s trichrome staining were performed 90 days after implantation. All rhBMP-2-added constructs induced the formation of well-differentiated mineralized woven bone surrounding the HASi scaffolds and bridging bone/implant interfaces as early as eight weeks after surgery. Bone regeneration appeared to develop earlier with the rhBMP-2 constructs than with the IGF-1 added construct. Constructs without any rhBMP-2 or IGF-1 showed osteoconductive properties limited to the bone junctions without bone ingrowths within the implantation site. In conclusion, the addition of rhBMP-2 to a HASi scaffold could promote bone generation in a large critical-size-defect.

  4. Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong, E-mail: cchen19@tigers.lsu.edu; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W. [Louisiana State University and LSU AgCenter, Department of Biological and Agricultural Engineering (United States); Gimble, Jeffrey M., E-mail: Jeffrey.Gimble@pbrc.edu [Tulane University School of Medicine, Center for Stem Cell Research & Regenerative Medicine (United States); Hayes, Daniel J., E-mail: danielhayes@lsu.edu [Louisiana State University and LSU AgCenter, Department of Biological and Agricultural Engineering (United States)

    2015-04-15

    Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell–particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix.

  5. Single Cell Analysis Linking Ribosomal (r)DNA and rRNA Copy Numbers to Cell Size and Growth Rate Provides Insights into Molecular Protistan Ecology.

    Science.gov (United States)

    Fu, Rao; Gong, Jun

    2017-11-01

    Ribosomal (r)RNA and rDNA have been golden molecular markers in microbial ecology. However, it remains poorly understood how ribotype copy number (CN)-based characteristics are linked with diversity, abundance, and activity of protist populations and communities observed at organismal levels. Here, we applied a single-cell approach to quantify ribotype CNs in two ciliate species reared at different temperatures. We found that in actively growing cells, the per-cell rDNA and rRNA CNs scaled with cell volume (CV) to 0.44 and 0.58 powers, respectively. The modeled rDNA and rRNA concentrations thus appear to be much higher in smaller than in larger cells. The observed rRNA:rDNA ratio scaled with CV 0.14 . The maximum growth rate could be well predicted by a combination of per-cell ribotype CN and temperature. Our empirical data and modeling on single-cell ribotype scaling are in agreement with both the metabolic theory of ecology and the growth rate hypothesis, providing a quantitative framework for linking cellular rDNA and rRNA CNs with body size, growth (activity), and biomass stoichiometry. This study also demonstrates that the expression rate of rRNA genes is constrained by cell size, and favors biomass rather than abundance-based interpretation of quantitative ribotype data in population and community ecology of protists. © 2017 The Authors. Journal of Eukaryotic Microbiology published by Wiley Periodicals, Inc. on behalf of International Society of Protistologists.

  6. Nanoparticle size and morphology control using ultrafast laser induced forward transfer of Ni thin films

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Abere, Michael J.; Schrider, Keegan J.; Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2013-08-26

    We have developed a nanoparticle (NP) printing technique using Ni thin film lift-off from glass substrates after ultrafast irradiation in air. Unique interactions of ultrafast laser pulses with thin films allow for control over NP faceting and size distributions. Control is achieved by changing the laser fluence, film thickness, and film-substrate distance. We demonstrate 20 nm Ni film removal from substrates and rapid NP printing, with size distributions centered at a 6 nm diameter. When the Ni film thickness is lowered to 10 nm, NPs are printed with distributions peaked at a 2 nm diameter.

  7. Surface receptor Toso controls B cell-mediated regulation of T cell immunity.

    Science.gov (United States)

    Yu, Jinbo; Duong, Vu Huy Hoang; Westphal, Katrin; Westphal, Andreas; Suwandi, Abdulhadi; Grassl, Guntram A; Brand, Korbinian; Chan, Andrew C; Föger, Niko; Lee, Kyeong-Hee

    2018-05-01

    The immune system is tightly controlled by regulatory processes that allow for the elimination of invading pathogens, while limiting immunopathological damage to the host. In the present study, we found that conditional deletion of the cell surface receptor Toso on B cells unexpectedly resulted in impaired proinflammatory T cell responses, which led to impaired immune protection in an acute viral infection model and was associated with reduced immunopathological tissue damage in a chronic inflammatory context. Toso exhibited its B cell-inherent immunoregulatory function by negatively controlling the pool of IL-10-competent B1 and B2 B cells, which were characterized by a high degree of self-reactivity and were shown to mediate immunosuppressive activity on inflammatory T cell responses in vivo. Our results indicate that Toso is involved in the differentiation/maintenance of regulatory B cells by fine-tuning B cell receptor activation thresholds. Furthermore, we showed that during influenza A-induced pulmonary inflammation, the application of Toso-specific antibodies selectively induced IL-10-competent B cells at the site of inflammation and resulted in decreased proinflammatory cytokine production by lung T cells. These findings suggest that Toso may serve as a novel therapeutic target to dampen pathogenic T cell responses via the modulation of IL-10-competent regulatory B cells.

  8. Mind over platter: pre-meal planning and the control of meal size in humans.

    Science.gov (United States)

    Brunstrom, J M

    2014-07-01

    It is widely accepted that meal size is governed by psychological and physiological processes that generate fullness towards the end of a meal. However, observations of natural eating behaviour suggest that this preoccupation with within-meal events may be misplaced and that the role of immediate post-ingestive feedback (for example, gastric stretch) has been overstated. This review considers the proposition that the locus of control is more likely to be expressed in decisions about portion size, before a meal begins. Consistent with this idea, we have discovered that people are extremely adept at estimating the 'expected satiety' and 'expected satiation' of different foods. These expectations are learned over time and they are highly correlated with the number of calories that end up on our plate. Indeed, across a range of foods, the large variation in expected satiety/satiation may be a more important determinant of meal size than relatively subtle differences in palatability. Building on related advances, it would also appear that memory for portion size has an important role in generating satiety after a meal has been consumed. Together, these findings expose the importance of planning and episodic memory in the control of appetite and food intake in humans.

  9. Cancerous epithelial cell lines shed extracellular vesicles with a bimodal size distribution that is sensitive to glutamine inhibition

    International Nuclear Information System (INIS)

    Santana, Steven Michael; Kirby, Brian J; Antonyak, Marc A; Cerione, Richard A

    2014-01-01

    Extracellular shed vesicles (ESVs) facilitate a unique mode of cell–cell communication wherein vesicle uptake can induce a change in the recipient cell's state. Despite the intensity of ESV research, currently reported data represent the bulk characterization of concentrated vesicle samples with little attention paid to heterogeneity. ESV populations likely represent diversity in mechanisms of formation, cargo and size. To better understand ESV subpopulations and the signaling cascades implicated in their formation, we characterize ESV size distributions to identify subpopulations in normal and cancerous epithelial cells. We have discovered that cancer cells exhibit bimodal ESV distributions, one small-diameter and another large-diameter population, suggesting that two mechanisms may govern ESV formation, an exosome population and a cancer-specific microvesicle population. Altered glutamine metabolism in cancer is thought to fuel cancer growth but may also support metastatic niche formation through microvesicle production. We describe the role of a glutaminase inhibitor, compound 968, in ESV production. We have discovered that inhibiting glutamine metabolism significantly impairs large-diameter microvesicle production in cancer cells. (paper)

  10. Rupturing Giant Plasma Membrane Vesicles to Form Micron-sized Supported Cell Plasma Membranes with Native Transmembrane Proteins.

    Science.gov (United States)

    Chiang, Po-Chieh; Tanady, Kevin; Huang, Ling-Ting; Chao, Ling

    2017-11-09

    Being able to directly obtain micron-sized cell blebs, giant plasma membrane vesicles (GPMVs), with native membrane proteins and deposit them on a planar support to form supported plasma membranes could allow the membrane proteins to be studied by various surface analytical tools in native-like bilayer environments. However, GPMVs do not easily rupture on conventional supports because of their high protein and cholesterol contents. Here, we demonstrate the possibility of using compression generated by the air-water interface to efficiently rupture GPMVs to form micron-sized supported membranes with native plasma membrane proteins. We demonstrated that not only lipid but also a native transmembrane protein in HeLa cells, Aquaporin 3 (AQP3), is mobile in the supported membrane platform. This convenient method for generating micron-sized supported membrane patches with mobile native transmembrane proteins could not only facilitate the study of membrane proteins by surface analytical tools, but could also enable us to use native membrane proteins for bio-sensing applications.

  11. Oxygen-controlled automated neural differentiation of mouse embryonic stem cells.

    Science.gov (United States)

    Mondragon-Teran, Paul; Tostoes, Rui; Mason, Chris; Lye, Gary J; Veraitch, Farlan S

    2013-03-01

    Automation and oxygen tension control are two tools that provide significant improvements to the reproducibility and efficiency of stem cell production processes. the aim of this study was to establish a novel automation platform capable of controlling oxygen tension during both the cell-culture and liquid-handling steps of neural differentiation processes. We built a bespoke automation platform, which enclosed a liquid-handling platform in a sterile, oxygen-controlled environment. An airtight connection was used to transfer cell culture plates to and from an automated oxygen-controlled incubator. Our results demonstrate that our system yielded comparable cell numbers, viabilities, metabolism profiles and differentiation efficiencies when compared with traditional manual processes. Interestingly, eliminating exposure to ambient conditions during the liquid-handling stage resulted in significant improvements in the yield of MAP2-positive neural cells, indicating that this level of control can improve differentiation processes. This article describes, for the first time, an automation platform capable of maintaining oxygen tension control during both the cell-culture and liquid-handling stages of a 2D embryonic stem cell differentiation process.

  12. Haptic shared control improves hot cell remote handling despite controller inaccuracies

    NARCIS (Netherlands)

    van Oosterhout, J.; Abbink, D. A.; Koning, J. F.; Boessenkool, H.; Wildenbeest, J. G. W.; Heemskerk, C. J. M.

    2013-01-01

    A promising solution to improve task performance in ITER hot cell remote handling is the use of haptic shared control. Haptic shared control can assist the human operator along a safe and optimal path with continuous guiding forces from an intelligent autonomous controller. Previous research tested

  13. Mechanobiological induction of long-range contractility by diffusing biomolecules and size scaling in cell assemblies

    Science.gov (United States)

    Dasbiswas, K.; Alster, E.; Safran, S. A.

    2016-06-01

    Mechanobiological studies of cell assemblies have generally focused on cells that are, in principle, identical. Here we predict theoretically the effect on cells in culture of locally introduced biochemical signals that diffuse and locally induce cytoskeletal contractility which is initially small. In steady-state, both the concentration profile of the signaling molecule as well as the contractility profile of the cell assembly are inhomogeneous, with a characteristic length that can be of the order of the system size. The long-range nature of this state originates in the elastic interactions of contractile cells (similar to long-range “macroscopic modes” in non-living elastic inclusions) and the non-linear diffusion of the signaling molecules, here termed mechanogens. We suggest model experiments on cell assemblies on substrates that can test the theory as a prelude to its applicability in embryo development where spatial gradients of morphogens initiate cellular development.

  14. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Science.gov (United States)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae

    2014-12-01

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl4 by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of 20 and 120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4-8 and 10-30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV-Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  15. Mechanical Model of Geometric Cell and Topological Algorithm for Cell Dynamics from Single-Cell to Formation of Monolayered Tissues with Pattern

    KAUST Repository

    Kachalo, Sëma

    2015-05-14

    Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly

  16. Core functions of the Web-of-Cells control scheme

    DEFF Research Database (Denmark)

    Evenblij, Berend; Rikos, Evangelos; Heussen, Kai

    In order to maintain frequency (balancing) and voltage control in the future power system, the ELECTRA Web-of-Cells (WoC) control scheme introduces six high-level use cases, which are Balance Restoration Control (BRC), Frequency Containment Control (FCC), Inertia Response Power Control (IRPC), Ba......), Balance Steering Control (BSC), Primary Voltage Control (PVC) and Post Primary Voltage Control (PPVC). This document presents the detailed description of the core functions that are needed and sufficient for controlling the grid in a Web-of-Cells architecture....

  17. Podocyte Number in Children and Adults: Associations with Glomerular Size and Numbers of Other Glomerular Resident Cells

    Science.gov (United States)

    Puelles, Victor G.; Douglas-Denton, Rebecca N.; Cullen-McEwen, Luise A.; Li, Jinhua; Hughson, Michael D.; Hoy, Wendy E.; Kerr, Peter G.

    2015-01-01

    Increases in glomerular size occur with normal body growth and in many pathologic conditions. In this study, we determined associations between glomerular size and numbers of glomerular resident cells, with a particular focus on podocytes. Kidneys from 16 male Caucasian-Americans without overt renal disease, including 4 children (≤3 years old) to define baseline values of early life and 12 adults (≥18 years old), were collected at autopsy in Jackson, Mississippi. We used a combination of immunohistochemistry, confocal microscopy, and design-based stereology to estimate individual glomerular volume (IGV) and numbers of podocytes, nonepithelial cells (NECs; tuft cells other than podocytes), and parietal epithelial cells (PECs). Podocyte density was calculated. Data are reported as medians and interquartile ranges (IQRs). Glomeruli from children were small and contained 452 podocytes (IQR=335–502), 389 NECs (IQR=265–498), and 146 PECs (IQR=111–206). Adult glomeruli contained significantly more cells than glomeruli from children, including 558 podocytes (IQR=431–746; P<0.01), 1383 NECs (IQR=998–2042; P<0.001), and 367 PECs (IQR=309–673; P<0.001). However, large adult glomeruli showed markedly lower podocyte density (183 podocytes per 106 µm3) than small glomeruli from adults and children (932 podocytes per 106 µm3; P<0.001). In conclusion, large adult glomeruli contained more podocytes than small glomeruli from children and adults, raising questions about the origin of these podocytes. The increased number of podocytes in large glomeruli does not match the increase in glomerular size observed in adults, resulting in relative podocyte depletion. This may render hypertrophic glomeruli susceptible to pathology. PMID:25568174

  18. Preparation of planar CH3NH3PbI3 thin films with controlled size using 1-ethyl-2-pyrrolidone as solvent

    International Nuclear Information System (INIS)

    Hao, Qiuyan; Chu, Yixia; Zheng, Xuerong; Liu, Zhenya; Liang, Liming; Qi, Jiakun; Zhang, Xin; Liu, Gang; Liu, Hui; Chen, Hongjian; Liu, Caichi

    2016-01-01

    Recently, planar perovskite solar cells based on CH 3 NH 3 PbI 3 have attracted many researcher's interest due to their unique advantages such as simple cell architecture, easy fabrication and potential multijunction construction comparing to the initial mesoporous structure. However, the preparation of planar perovskite films with high quality is still in challenge. In this paper, we developed a vapor-assisted solution process using a novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) instead of the traditional N, N-dimethylformamide (DMF) to construct a high-quality perovskite CH 3 NH 3 PbI 3 thin film with pure phase, high compactness, small surface roughness and controlled size. The phase evolution and growth mechanism of the perovskite films are also discussed. Utilizing the NEP of low volatility and moderate boiling point as solvent, we dried the PbI 2 -NEP precursor films at different temperature under vacuum and then obtained PbI 2 thin films with different crystalline degree from amorphous to highly crystalline. The perovskite films with crystal size ranged from hundreds of nanometers to several micrometers can be prepared by reacting the PbI 2 films of different crystalline degree with CH 3 NH 3 I vapor. Moreover, planar-structured solar cells combining the perovskite film with TiO 2 and spiro-OMeTAD as the electron and holes transporting layer achieves a power conversion efficiency of 10.2%. - Highlights: • A novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) was used to construct high-quality perovskite CH 3 NH 3 PbI 3 thin film. • The CH 3 NH 3 PbI 3 grain with different sizes ranged from hundreds of nanometers to several micrometers can be obtained. • Planar-structured perovskite CH 3 NH 3 PbI 3 solar cells using NEP as solvent achieves a power conversion efficiency of 10.2%.

  19. Neural control of colonic cell proliferation.

    Science.gov (United States)

    Tutton, P J; Barkla, D H

    1980-03-15

    The mitotic rate in rat colonic crypts and in dimethylhydrazine-induced colonic carcinomas was measured using a stathmokinetic technique. In sympathectomized animals cell proliferation was retarded in the crypts but not in the tumors, whereas in animals treated with Metaraminol, a drug which releases norepinephrine from nerve terminals, crypt cell but not tumor cell proliferation was accelerated. Blockade of alpha-adrenoceptors also inhibited crypt cell proliferation. However, stimulation of beta-adrenoceptors inhibited and blockade of beta-adrenoceptors accelerated tumor cell proliferation without influencing crypt cell proliferation. Injection of either serotonin or histamine stimulated tumor but not crypt cell proliferation and blockade or serotonin receptors or histamine H2-receptors inhibited tumor cell proliferation. It is postulated that cell proliferation in the colonic crypts, like that in the jejunal crypts, is under both endocrine and autonomic neural control whereas colonic tumor cell division is subject to endocrine regulation alone.

  20. A cell-to-cell Markovian model for the reliability of a digital control system of a steam generator

    International Nuclear Information System (INIS)

    Gomes, Ian B.; Melo, Paulo F.F. Frutuoso e; Saldanha, Pedro L.C.

    2013-01-01

    With the shift of technology from analog to digital systems, due to the obsolescence of the older analog systems and the functional advantages of the digital ones, existing nuclear power plants have begun to replace their systems, while newer plants use digital systems from the beginning of their construction. However, the process of risk-informed analysis for digital systems has not been satisfactorily developed yet. Traditional methods, such as fault trees, have limitations, while dynamic methods are still in the tests stage and may be difficult to be applied to a real size probabilistic safety assessment (PSA) model. The objective of this paper is to study and obtain a better comprehension of the Markov/CCMT method, a method that combines the traditional Markovian methodology with the cell-to-cell mapping technique for representing the possible failure events that can be originated in the dynamic interactions between the instrumentation and control system and the controlled process, and among the various components of the digital system. The study consists of the simulation of a digital water level control system of the steam generator of a PWR plant. From this simulation, a Failure Modes and Effects Analysis (FMEA) was made and the information obtained was used to calculate the system reliability, using the Markov/CCMT methodology. The results show that the method is capable of identifying the most probable causes for a possible failure of the digital system. (author)

  1. A High-Yield Synthesis of Chalcopyrite CuInS2 Nanoparticles with Exceptional Size Control

    Directory of Open Access Journals (Sweden)

    Chivin Sun

    2009-01-01

    Full Text Available We report high-yield and efficient size-controlled syntheses of Chalcopyrite CuInS2 nanoparticles by decomposing molecular single source precursors (SSPs via microwave irradiation in the presence of 1,2-ethanedithiol at reaction temperatures as low as 100°C and times as short as 30 minutes. The nanoparticles sizes were 1.8 nm to 10.8 nm as reaction temperatures were varied from 100°C to 200°C with the bandgaps from 2.71 eV to 1.28 eV with good size control and high yields (64%–95%. The resulting nanoparticles were analyzed by XRD, UV-Vis, ICP-OES, XPS, SEM, EDS, and HRTEM. Titration studies by 1H NMR using SSP 1 with 1,2-ethanedithiol and benzyl mercaptan were conducted to elucidate the formation of Chalcopyrite CuInS2 nanoparticles.

  2. High throughput single-cell and multiple-cell micro-encapsulation.

    Science.gov (United States)

    Lagus, Todd P; Edd, Jon F

    2012-06-15

    Microfluidic encapsulation methods have been previously utilized to capture cells in picoliter-scale aqueous, monodisperse drops, providing confinement from a bulk fluid environment with applications in high throughput screening, cytometry, and mass spectrometry. We describe a method to not only encapsulate single cells, but to repeatedly capture a set number of cells (here we demonstrate one- and two-cell encapsulation) to study both isolation and the interactions between cells in groups of controlled sizes. By combining drop generation techniques with cell and particle ordering, we demonstrate controlled encapsulation of cell-sized particles for efficient, continuous encapsulation. Using an aqueous particle suspension and immiscible fluorocarbon oil, we generate aqueous drops in oil with a flow focusing nozzle. The aqueous flow rate is sufficiently high to create ordering of particles which reach the nozzle at integer multiple frequencies of the drop generation frequency, encapsulating a controlled number of cells in each drop. For representative results, 9.9 μm polystyrene particles are used as cell surrogates. This study shows a single-particle encapsulation efficiency P(k=1) of 83.7% and a double-particle encapsulation efficiency P(k=2) of 79.5% as compared to their respective Poisson efficiencies of 39.3% and 33.3%, respectively. The effect of consistent cell and particle concentration is demonstrated to be of major importance for efficient encapsulation, and dripping to jetting transitions are also addressed. Continuous media aqueous cell suspensions share a common fluid environment which allows cells to interact in parallel and also homogenizes the effects of specific cells in measurements from the media. High-throughput encapsulation of cells into picoliter-scale drops confines the samples to protect drops from cross-contamination, enable a measure of cellular diversity within samples, prevent dilution of reagents and expressed biomarkers, and amplify

  3. Estimation and control of droplet size and frequency in projected spray mode of a gas metal arc welding (GMAW) process.

    Science.gov (United States)

    Anzehaee, Mohammad Mousavi; Haeri, Mohammad

    2011-07-01

    New estimators are designed based on the modified force balance model to estimate the detaching droplet size, detached droplet size, and mean value of droplet detachment frequency in a gas metal arc welding process. The proper droplet size for the process to be in the projected spray transfer mode is determined based on the modified force balance model and the designed estimators. Finally, the droplet size and the melting rate are controlled using two proportional-integral (PI) controllers to achieve high weld quality by retaining the transfer mode and generating appropriate signals as inputs of the weld geometry control loop. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  4. Temporal Airy pulses control cell poration

    Directory of Open Access Journals (Sweden)

    S. Courvoisier

    2016-07-01

    Full Text Available We show that spectral phase shaping of fs-laser pulses can be used to optimize laser-cell membrane interactions in water environment. The energy and peak intensity thresholds required for cell poration with single pulse in the nJ range can be significantly reduced (25% reduction in energy and 88% reduction in peak intensity by using temporal Airy pulses, controlled by positive third order dispersion, as compared to bandwidth limited pulses. Temporal Airy pulses are also effective to control the morphology of the induced pores, with prospective applications from cellular to tissue opto-surgery and transfection.

  5. Nanotoxicity of silver nanoparticles to red blood cells: size dependent adsorption, uptake, and hemolytic activity.

    Science.gov (United States)

    Chen, Li Qiang; Fang, Li; Ling, Jian; Ding, Cheng Zhi; Kang, Bin; Huang, Cheng Zhi

    2015-03-16

    Silver nanoparticles (AgNPs) are increasingly being used as antimicrobial agents and drug carriers in biomedical fields. However, toxicological information on their effects on red blood cells (RBCs) and the mechanisms involved remain sparse. In this article, we examined the size dependent nanotoxicity of AgNPs using three different characteristic sizes of 15 nm (AgNPs15), 50 nm (AgNPs50), and 100 nm (AgNPs100) against fish RBCs. Optical microscopy and transmission electron microscopy observations showed that AgNPs exhibited a size effect on their adsorption and uptake by RBCs. The middle sized AgNPs50, compared with the smaller or bigger ones, showed the highest level of adsorption and uptake by the RBCs, suggesting an optimal size of ∼50 nm for passive uptake by RBCs. The toxic effects determined based on the hemolysis, membrane injury, lipid peroxidation, and antioxidant enzyme production were fairly size and dose dependent. In particular, the smallest sized AgNPs15 displayed a greater ability to induce hemolysis and membrane damage than AgNPs50 and AgNPs100. Such cytotoxicity induced by AgNPs should be attributed to the direct interaction of the nanoparticle with the RBCs, resulting in the production of oxidative stress, membrane injury, and subsequently hemolysis. Overall, the results suggest that particle size is a critical factor influencing the interaction between AgNPs and the RBCs.

  6. Cluster size matters: Size-driven performance of subnanometer clusters in catalysis, electrocatalysis and Li-air batteries

    Science.gov (United States)

    Vajda, Stefan

    2015-03-01

    This paper discusses the strongly size-dependent performance of subnanometer cluster based catalysts in 1) heterogeneous catalysis, 2) electrocatalysis and 3) Li-air batteries. The experimental studies are based on I. fabrication of ultrasmall clusters with atomic precision control of particle size and their deposition on oxide and carbon based supports; II. test of performance, III. in situand ex situ X-ray characterization of cluster size, shape and oxidation state; and IV.electron microscopies. Heterogeneous catalysis. The pronounced effect of cluster size and support on the performance of the catalyst (catalyst activity and the yield of Cn products) will be illustrated on the example of nickel and cobalt clusters in Fischer-Tropsch reaction. Electrocatalysis. The study of the oxygen evolution reaction (OER) on size-selected palladium clusters supported on ultrananocrystalline diamond show pronounced size effects. While Pd4 clusters show no reaction, Pd6 and Pd17 clusters are among the most active catalysts known (in in terms of turnover rate per Pd atom). The system (soft-landed Pd4, Pd6, or Pd17 clusters on an UNCD Si coated electrode) shows stable electrochemical potentials over several cycles, and the characterization of the electrodes show no evidence for evolution or dissolution of either the support Theoretical calculations suggest that this striking difference may be a demonstration that bridging Pd-Pd sites, which are only present in three-dimensional clusters, are active for the oxygen evolution reaction in Pd6O6. Li-air batteries. The studies show that sub-nm silver clusters have dramatic size-dependent effect on the lowering of the overpotential, charge capacity, morphology of the discharge products, as well as on the morphology of the nm size building blocks of the discharge products. The results suggest that by precise control of the active surface sites on the cathode, the performance of Li-air cells can be significantly improved

  7. The synthesis and characterization of platinum nanoparticles: a method of controlling the size and morphology

    International Nuclear Information System (INIS)

    Long, Nguyen Viet; Hayakawa, Tomokatsu; Lakshminarayana, Gandham; Nogami, Masayuki; Chien, Nguyen Duc; Hirata, Hirohito

    2010-01-01

    In this paper, Pt nanoparticles with good shapes of nanocubes and nano-octahedra and well-controlled sizes in the range 5-7 and 8-12 nm, respectively, have been successfully synthesized. The modified polyol method by adding silver nitrate and varying the molar ratio of the solutions of silver nitrate and H 2 PtCl 6 has been used to produce Pt nanoparticles of the size and shape to be controlled. The size and morphology of Pt nanoparticles have been studied by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The results have shown that their very sharp and good shapes exist in the main forms of cubic, cuboctahedral, octahedral and tetrahedral shapes directly related to the crystal nucleation along various directions of the {100} cubic, {111} octahedral and {111} tetrahedral facets during synthesis. In particular, various irregular and new shapes of Pt nanoparticles have been found. Here, it is concluded that the role of silver ions has to be considered as an important factor for promoting and controlling the development of Pt nanoparticles of {100} cubic, {111} octahedral and {111} tetrahedral facets, and also directly orienting the growth and formation of Pt nanoparticles.

  8. Effect of Mixture Pressure and Equivalence Ratio on Detonation Cell Size for Hydrogen-Air Mixtures

    Science.gov (United States)

    2015-06-01

    In order to design combustion chambers for detonating engines, specifically PDEs and RDEs , the cell size is needed. Higher than atmospheric...8 Figure 4. RDE dimensions ................................................................................................ 11...Technology DDT Deflagration to Detonation MAPE Mean Absolute Percent Error PDE Pulsed Detonation Engine RDE Rotating Detonation Engine ZND

  9. Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition

    NARCIS (Netherlands)

    Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.

    2014-01-01

    A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ?100 nm were

  10. Intervention of oxygen-control ability to radiation sensitivity, cell aging and cell transformation

    International Nuclear Information System (INIS)

    Yoshii, Hanako; Watanabe, Masami

    2009-01-01

    Oxygen is essential for life, and cells have therefore developed numerous adaptive responses to oxygen change. Here, we examined the difference in oxygen-control functions of human (HE), mouse (ME), and Syrian hamster embryo (SHE) cells cultured under different oxygen conditions (0.5%, 2% and 20%), and also examined whether oxygen tensions contributed to cellular lifespan and transformation. HE cells had their replicative lifespan slightly extended under hypoxic (0.5% and 2% oxygen) conditions, but were not immortalized under any of the oxygen concentrations. On the other hand, although ME cells cultured under 20% oxygen tension decreased their proliferation potency temporarily at early stage, all rodent cells were immortalized and acquired anchorage-independency, regardless of oxygen tension. These results suggest that cellular oxygen control function is related to sensitivities cellular immortalization and transformation. To understand intervention of oxygen control ability on cellular immortalization and transformation, we examined the intracellular oxidative level, mitochondria functions and radiation sensitivity. Intracellular oxidative levels of hypoxically cultured rodent cells were significantly enhanced. Mitochondrial membrane potential was altered depend on oxygen tensions, but the change was not parallel to mitochondria number in rodent cells. ME cells were particularly sensitive to oxygen change, and showed a clear oxygen effect on the X-ray survival. However, there was no difference in frequency of radiation-induced micronuclei between HE and ME cells. These results suggest that the response to oxygen change differs markedly in HE and rodent cells. (author)

  11. Size control of MnFe2O4 nanoparticles in electric double layered magnetic fluid synthesis

    International Nuclear Information System (INIS)

    Aquino, R.; Tourinho, F.A.; Itri, R.; E Lara, M.C.F.L.; Depeyrot, J.

    2002-01-01

    We propose a method based on the pH of the synthesis to control the nanoparticle size during the ferrofluid elaboration. The particle diameter is determined by means of X-ray diffraction experiments. The measured mean size depends on the type of buffer used during the coprecipitation process. The results therefore confirm that the nanoparticle size can be monitored by the hydroxide concentration and suggest to consider the induced interplay between nucleation and crystal growth

  12. Size-controllable synthesis of nanosized-TiO2 anatase using porous Vycor glass as template

    International Nuclear Information System (INIS)

    Mazali, I.O.; Filho, A.G. Souza; Viana, B.C.; Filho, J. Mendes; Alves, O.L.

    2006-01-01

    In this paper we report the synthesis and characterization of TiO 2 nanocrystal dispersed into a porous Vycor glass. We have obtained very small TiO 2 nanocrystals in the anatase form. The nanocrystal size is controlled via the mass increment only thus preventing the growth through the coalescence process. The nanocrystal size was monitored through transmission electron microscope and Raman scattering. The coalescence control is attributed due to the obtention of nanocrystals dispersed into the host and to the terminal bonds present in the porous which act as an anchor thus resulting in a low diffusion of the nanocrystals through the porous network

  13. Quality control system response to stochastic growth of amyloid fibrils

    DEFF Research Database (Denmark)

    Pigolotti, S.; Lizana, L.; Sneppen, K.

    2013-01-01

    We introduce a stochastic model describing aggregation of misfolded proteins and degradation by the protein quality control system in a single cell. Aggregate growth is contrasted by the cell quality control system, that attacks them at different stages of the growth process, with an efficiency...... that decreases with their size. Model parameters are estimated from experimental data. Two qualitatively different behaviors emerge: a homeostatic state, where the quality control system is stable and aggregates of large sizes are not formed, and an oscillatory state, where the quality control system...

  14. Microfluidic Approach to Cell Microencapsulation.

    Science.gov (United States)

    Sharma, Varna; Hunckler, Michael; Ramasubramanian, Melur K; Opara, Emmanuel C; Katuri, Kalyan C

    2017-01-01

    Bioartificial pancreas made of insulin-secreting islets cells holds great promise in the treatment of individuals with Type-1 diabetes. Successful islet cell microencapsulation in biopolymers is a key step for providing immunoisolation of transplanted islet cells. Because of the variability in the size and shape of pancreatic islets, one of the main obstacles in their microencapsulation is the inability to consistently control shape, size, and microstructure of the encapsulating biopolymer capsule. In this chapter, we provide a detailed description of a microfluidic approach to islet cell encapsulation in alginate that might address the microencapsulation challenges.

  15. The Effect of Pulsatile Flow on bMSC-Derived Endothelial-Like Cells in a Small-Sized Artificial Vessel Made by 3-Dimensional Bioprinting

    Directory of Open Access Journals (Sweden)

    Kang Woog Lee

    2018-01-01

    Full Text Available Replacement of small-sized vessels is still challenging. This study is aimed at investigating the possibility of small-sized artificial vessels made by 3-dimensional bioprinting and the effect of pulsatile flow on bMSC-derived endothelial-like cells. Cells were harvested from rabbit bone marrow and primary cultured with or without growth factors. Endothelial differentiation was confirmed by the Matrigel tube formation assay, Western blot, and qRT-PCR. In addition, embedment of endothelial-like cells in an artificial vessel was made by 3-dimensional bioprinting, and the pulsatile flow was performed. For pumped and nonpumped groups, qRT-PCR was performed on CD31 and VE-cadherin gene expression. Endothelial-like cells showed increased gene expression of CD31 and VE-cadherin, and tube formation is observed at each week. Endothelial-like cells grow well in a small-sized artificial vessel made by 3-dimensional bioprinting and even express higher endothelial cell markers when they undergo pulsatile flow condition. Moreover, the pulsatile flow condition gives a positive effect for cell observation not only on the sodium alginate hydrogel layer but also on the luminal surface of the artificial vessel wall. We have developed an artificial vessel, which is a mixture of cells and carriers using a 3-dimensional bioprinting method, and applied pulsatile flow using a peristaltic pump, and we also demonstrated cell growth and differentiation into endothelial cells. This study suggests guidelines regarding a small-sized artificial vessel in the field of tissue engineering.

  16. Functional polythiophene nanoparticles: Size-controlled electropolymerization and ion selective response

    DEFF Research Database (Denmark)

    Si, P.C.; Chi, Qijin; Li, Z.S.

    2007-01-01

    polymerization to form polymer nanoparticles or clusters by which the size of the polymer nanoparticles can further be controlled electrochemically. The electropolymerization was monitored in situ by scanning tunneling microscopy to unravel the dynamics of the process and possible mechanisms. These are further......We have synthesized a thiophene derivative, (4-benzeno-15-crown-5 ether)-thiophene-3-methylene-amine (BTA), which was used as a monomer for electrochemical polymerization on metallic surfaces to prepare functional polymer films. Self-assembly of BTA monomers on Au(111) surfaces promotes ordered...

  17. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Directory of Open Access Journals (Sweden)

    Melda Sonmez

    Full Text Available The role of membrane fluidity in determining red blood cell (RBC deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol using ektacytometry and electron paramagnetic resonance (EPR spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01. The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  18. Antibody-independent control of gamma-herpesvirus latency via B cell induction of anti-viral T cell responses.

    Directory of Open Access Journals (Sweden)

    Kelly B McClellan

    2006-06-01

    Full Text Available B cells can use antibody-dependent mechanisms to control latent viral infections. It is unknown whether this represents the sole function of B cells during chronic viral infection. We report here that hen egg lysozyme (HEL-specific B cells can contribute to the control of murine gamma-herpesvirus 68 (gammaHV68 latency without producing anti-viral antibody. HEL-specific B cells normalized defects in T cell numbers and proliferation observed in B cell-/- mice during the early phase of gammaHV68 latency. HEL-specific B cells also reversed defects in CD8 and CD4 T cell cytokine production observed in B cell-/- mice, generating CD8 and CD4 T cells necessary for control of latency. Furthermore, HEL-specific B cells were able to present virally encoded antigen to CD8 T cells. Therefore, B cells have antibody independent functions, including antigen presentation, that are important for control of gamma-herpesvirus latency. Exploitation of this property of B cells may allow enhanced vaccine responses to chronic virus infection.

  19. Particle size and surface charge affect particle uptake by human dendritic cells in an in vitro model

    DEFF Research Database (Denmark)

    Foged, Camilla; Brodin, Birger; Frøkjær, Sven

    2005-01-01

    Current vaccine development includes optimization of antigen delivery to antigen presenting cells, such as dendritic cells (DC). Particulate systems have attracted increasing attention in the development of vaccine delivery systems. In the present study, we investigated DC uptake of model...... fluorescent polystyrene particles with a broad size range and variable surface properties. Localization of particles was investigated using confocal laser scanning microscopy and uptake was quantified by flow cytometry. Immature DC were generated from mononuclear cells isolated from human blood...

  20. Responses of Algal Cells to Engineered Nanoparticles Measured as Algal Cell Population, Chlorophyll a, and Lipid Peroxidation: Effect of Particle Size and Type

    Directory of Open Access Journals (Sweden)

    D. M. Metzler

    2012-01-01

    Full Text Available This paper investigated toxicity of three engineered nanoparticles (ENP, namely, Al2O3, SiO2, and TiO2 to the unicellular green algae, exemplified by Pseudokirchneriella subcapitata with an emphasis on particle size. The changes in pH, cell counts, chlorophyll a, and lipid peroxidation were used to measure the responses of the algal species to ENP. The most toxic particle size was TiO2 at 42 nm with an EC20 of 5.2 mg/L and Al2O3 at 14–18 nm with an EC20 of 5.1 mg/L. SiO2 was the least toxic with an EC20 of 318 mg/L. Toxicity was positively related to the surface charge of both ENP and algae. The chlorophyll content of the algal cells was influenced by the presence of ENP, which resulted in limited light and availability of nutrients due to increase in turbidity and nutrient adsorption onto the ENP surface, separately. Lipid peroxidation was attributed to reactive oxygen species (ROS. Fast reaction between algal cells and ROS due to direct contact between TiO2 and algal cells is an important factor for lipid peroxidation.

  1. Particle Size Effects of TiO2 Layers on the Solar Efficiency of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Jer Jeng

    2013-01-01

    Full Text Available Large particle sizes having a strong light scattering lead to a significantly decreased surface area and small particle sizes having large surface area lack light-scattering effect. How to combine large and small particle sizes together is an interesting work for achieving higher solar efficiency. In this work, we investigate the solar performance influence of the dye-sensitized solar cells (DSSCs by the multiple titanium oxide (TiO2 layers with different particle sizes. It was found that the optimal TiO2 thickness depends on the particle sizes of TiO2 layers for achieving the maximum efficiency. The solar efficiency of DSSCs prepared by triple TiO2 layers with different particle sizes is higher than that by double TiO2 layers for the same TiO2 thickness. The choice of particle size in the bottom layer is more important than that in the top layer for achieving higher solar efficiency. The choice of the particle sizes in the middle layer depends on the particle sizes in the bottom and top layers. The mixing of the particle sizes in the middle layer is a good choice for achieving higher solar efficiency.

  2. Nanoparticles of lipid monolayer shell and biodegradable polymer core for controlled release of paclitaxel: effects of surfactants on particles size, characteristics and in vitro performance.

    Science.gov (United States)

    Liu, Yutao; Pan, Jie; Feng, Si-Shen

    2010-08-16

    This work developed a system of nanoparticles of lipid monolayer shell and biodegradable polymer core for controlled release of anticancer drugs with paclitaxel as a model drug, in which the emphasis was given to the effects of the surfactant type and the optimization of the emulsifier amount used in the single emulsion solvent evaporation/extraction process for the nanoparticle preparation on the particle size, characters and in vitro performance. The drug loaded nanoparticles were characterized by laser light scattering (LLS) for size and size distribution, field-emission scanning electron microscopy (FESEM) for surface morphology, X-ray photoelectron spectroscopy (XPS) for surface chemistry, zetasizer for surface charge, and high performance liquid chromatography (HPLC) for drug encapsulation efficiency and in vitro drug release kinetics. MCF-7 breast cancer cells were employed to evaluate the cellular uptake and cytotoxicity. It was found that phospholipids of short chains such as 1,2-dilauroylphosphatidylocholine (DLPC) have great advantages over the traditional emulsifier poly(vinyl alcohol) (PVA), which is used most often in the literature, in preparation of nanoparticles of biodegradable polymers such as poly(D,L-lactide-co-glycolide) (PLGA) for desired particle size, character and in vitro cellular uptake and cytotoxicity. After incubation with MCF-7 cells at 0.250 mg/ml NP concentration, the coumarin-6 loaded PLGA NPs of DLPC shell showed more effective cellular uptake versus those of PVA shell. The analysis of IC(50), i.e. the drug concentration at which 50% of the cells are killed, demonstrated that our DLPC shell PLGA core NP formulation of paclitaxel could be 5.88-, 5.72-, 7.27-fold effective than the commercial formulation Taxol after 24, 48, 72h treatment, respectively. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  3. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    OpenAIRE

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-01-01

    Introduction: Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. Aim: To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. Methods: An opportunistic sample of 90 men from the community were recru...

  4. The transcription factor Swi4 is target for PKA regulation of cell size at the G1 to S transition in Saccharomyces cerevisiae.

    Science.gov (United States)

    Amigoni, Loredana; Colombo, Sonia; Belotti, Fiorella; Alberghina, Lilia; Martegani, Enzo

    2015-08-03

    To investigate the specific target of PKA in the regulation of cell cycle progression and cell size we developed a new approach using the yeast strain GG104 bearing a deletion in adenylate cyclase gene and permeable to cAMP ( cyr1Δ, pde2Δ, msn2Δ, msn4Δ). In this strain the PKA activity is absent and can be activated by addition of cAMP in the medium, without any other change of the growth conditions. In the present work we show that the activation of PKA by exogenous cAMP in the GG104 strain exponentially growing in glucose medium caused a marked increase of cell size and perturbation of cell cycle with a transient arrest of cells in G1, followed by an accumulation of cells in G2/M phase with a minimal change in the growth rate. Deletion of CLN1 gene, but not of CLN2, abolished the transient G1 phase arrest. Consistently we found that PKA activation caused a transcriptional repression of CLN1 gene. Transcription of CLN1 is controlled by SBF and MBF dual-regulated promoter. We found that also the deletion of SWI4 gene abolished the transient G1 arrest suggesting that Swi4 is a target responsible for PKA modulation of G1/S phase transition. We generated a SWI4 allele mutated in the consensus site for PKA (Swi4(S159A)) and we found that expression of Swi4(S159A) protein in the GG104-Swi4Δ strain did not restore the transient G1 arrest induced by PKA activation, suggesting that Swi4 phosphorylation by PKA regulates CLN1 gene expression and G1/S phase transition.

  5. Covariate adjustments in randomized controlled trials increased study power and reduced biasedness of effect size estimation.

    Science.gov (United States)

    Lee, Paul H

    2016-08-01

    This study aims to show that under several assumptions, in randomized controlled trials (RCTs), unadjusted, crude analysis will underestimate the Cohen's d effect size of the treatment, and an unbiased estimate of effect size can be obtained only by adjusting for all predictors of the outcome. Four simulations were performed to examine the effects of adjustment on the estimated effect size of the treatment and power of the analysis. In addition, we analyzed data from the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study (older adults aged 65-94), an RCT with three treatment arms and one control arm. We showed that (1) the number of unadjusted covariates was associated with the effect size of the treatment; (2) the biasedness of effect size estimation was minimized if all covariates were adjusted for; (3) the power of the statistical analysis slightly decreased with the number of adjusted noise variables; and (4) exhaustively searching the covariates and noise variables adjusted for can lead to exaggeration of the true effect size. Analysis of the ACTIVE study data showed that the effect sizes adjusting for covariates of all three treatments were 7.39-24.70% larger than their unadjusted counterparts, whereas the effect size would be elevated by at most 57.92% by exhaustively searching the variables adjusted for. All covariates of the outcome in RCTs should be adjusted for, and if the effect of a particular variable on the outcome is unknown, adjustment will do more good than harm. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Manipulation of Auxin Response Factor 19 affects seed size in the woody perennial Jatropha curcas

    Science.gov (United States)

    Sun, Yanwei; Wang, Chunming; Wang, Ning; Jiang, Xiyuan; Mao, Huizhu; Zhu, Changxiang; Wen, Fujiang; Wang, Xianghua; Lu, Zhijun; Yue, Genhua; Xu, Zengfu; Ye, Jian

    2017-01-01

    Seed size is a major determinant of seed yield but few is known about the genetics controlling of seed size in plants. Phytohormones cytokinin and brassinosteroid were known to be involved in the regulation of herbaceous plant seed development. Here we identified a homolog of Auxin Response Factor 19 (JcARF19) from a woody plant Jatropha curcas and genetically demonstrated its functions in controlling seed size and seed yield. Through Virus Induced Gene Silencing (VIGS), we found that JcARF19 was a positive upstream modulator in auxin signaling and may control plant organ size in J. curcas. Importantly, transgenic overexpression of JcARF19 significantly increased seed size and seed yield in plants Arabidopsis thaliana and J. curcas, indicating the importance of auxin pathway in seed yield controlling in dicot plants. Transcripts analysis indicated that ectopic expression of JcARF19 in J. curcas upregulated auxin responsive genes encoding essential regulators in cell differentiation and cytoskeletal dynamics of seed development. Our data suggested the potential of improving seed traits by precisely engineering auxin signaling in woody perennial plants. PMID:28102350

  7. Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy 125I and 192Ir sources and 60Co cell irradiation.

    Science.gov (United States)

    Villegas, Fernanda; Tilly, Nina; Ahnesjö, Anders

    2013-09-07

    The stochastic nature of ionizing radiation interactions causes a microdosimetric spread in energy depositions for cell or cell nucleus-sized volumes. The magnitude of the spread may be a confounding factor in dose response analysis. The aim of this work is to give values for the microdosimetric spread for a range of doses imparted by (125)I and (192)Ir brachytherapy radionuclides, and for a (60)Co source. An upgraded version of the Monte Carlo code PENELOPE was used to obtain frequency distributions of specific energy for each of these radiation qualities and for four different cell nucleus-sized volumes. The results demonstrate that the magnitude of the microdosimetric spread increases when the target size decreases or when the energy of the radiation quality is reduced. Frequency distributions calculated according to the formalism of Kellerer and Chmelevsky using full convolution of the Monte Carlo calculated single track frequency distributions confirm that at doses exceeding 0.08 Gy for (125)I, 0.1 Gy for (192)Ir, and 0.2 Gy for (60)Co, the resulting distribution can be accurately approximated with a normal distribution. A parameterization of the width of the distribution as a function of dose and target volume of interest is presented as a convenient form for the use in response modelling or similar contexts.

  8. Cell fate reprogramming by control of intracellular network dynamics

    Science.gov (United States)

    Zanudo, Jorge G. T.; Albert, Reka

    Identifying control strategies for biological networks is paramount for practical applications that involve reprogramming a cell's fate, such as disease therapeutics and stem cell reprogramming. Although the topic of controlling the dynamics of a system has a long history in control theory, most of this work is not directly applicable to intracellular networks. Here we present a network control method that integrates the structural and functional information available for intracellular networks to predict control targets. Formulated in a logical dynamic scheme, our control method takes advantage of certain function-dependent network components and their relation to steady states in order to identify control targets, which are guaranteed to drive any initial state to the target state with 100% effectiveness and need to be applied only transiently for the system to reach and stay in the desired state. We illustrate our method's potential to find intervention targets for cancer treatment and cell differentiation by applying it to a leukemia signaling network and to the network controlling the differentiation of T cells. We find that the predicted control targets are effective in a broad dynamic framework. Moreover, several of the predicted interventions are supported by experiments. This work was supported by NSF Grant PHY 1205840.

  9. Minimizing cell size dependence in micromagnetics simulations with thermal noise

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, E [Departamento de Ingenieria Electromecanica, Universidad de Burgos, Plaza Misael Banuelos, s/n, E-09001, Burgos (Spain); Lopez-DIaz, L [Departamento de Fisica Aplicada. Universidad Salamanca. Plaza de la Merced s/n. Salamanca E-37008 (Spain); Torres, L [Departamento de Fisica Aplicada. Universidad Salamanca. Plaza de la Merced s/n. Salamanca E-37008 (Spain); GarcIa-Cervera, C J [Department of Mathematics. University of California, Santa Barbara, CA 93106 (United States)

    2007-02-21

    Langevin dynamics treats finite temperature effects in a micromagnetics framework by adding a thermal fluctuation field to the effective field. Several works have addressed the dependence of numerical results on the cell size used to split the ferromagnetic samples on the nanoscale regime. In this paper, some former problems dealing with the dependence on the spatial discretization at finite temperature have been revised. We have focused our attention on the stability of the numerical schemes used to integrate the Langevin equation. In particular, a detailed analysis of results was carried out as a function of the time step. It was confirmed that the mentioned dependence can be minimized if an unconditional stable integration method is used to numerically solve the Langevin equation.

  10. Minimizing cell size dependence in micromagnetics simulations with thermal noise

    International Nuclear Information System (INIS)

    MartInez, E; Lopez-DIaz, L; Torres, L; GarcIa-Cervera, C J

    2007-01-01

    Langevin dynamics treats finite temperature effects in a micromagnetics framework by adding a thermal fluctuation field to the effective field. Several works have addressed the dependence of numerical results on the cell size used to split the ferromagnetic samples on the nanoscale regime. In this paper, some former problems dealing with the dependence on the spatial discretization at finite temperature have been revised. We have focused our attention on the stability of the numerical schemes used to integrate the Langevin equation. In particular, a detailed analysis of results was carried out as a function of the time step. It was confirmed that the mentioned dependence can be minimized if an unconditional stable integration method is used to numerically solve the Langevin equation

  11. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene

    KAUST Repository

    Cui, X.; Chen, K.; Xing, H.; Yang, Q.; Krishna, R.; Bao, Z.; Wu, H.; Zhou, W.; Dong, Xinglong; Han, Y.; Li, B.; Ren, Q.; Zaworotko, M. J.; Chen, B.

    2016-01-01

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination

  12. Developmental regulation of nucleolus size during Drosophila eye differentiation.

    Directory of Open Access Journals (Sweden)

    Nicholas E Baker

    Full Text Available When cell cycle withdrawal accompanies terminal differentiation, biosynthesis and cellular growth are likely to change also. In this study, nucleolus size was monitored during cell fate specification in the Drosophila eye imaginal disc using fibrillarin antibody labeling. Nucleolus size is an indicator of ribosome biogenesis and can correlate with cellular growth rate. Nucleolar size was reduced significantly during cell fate specification and differentiation, predominantly as eye disc cells entered a cell cycle arrest that preceded cell fate specification. This reduction in nucleolus size required Dpp and Hh signaling. A transient enlargement of the nucleolus accompanied cell division in the Second Mitotic Wave. Nucleoli continued to diminish in postmitotic cells following fate specification. These results suggest that cellular growth is regulated early in the transition from proliferating progenitor cells to terminal cell fate specification, contemporary with regulation of the cell cycle, and requiring the same extracellular signals.

  13. Developmental regulation of nucleolus size during Drosophila eye differentiation.

    Science.gov (United States)

    Baker, Nicholas E

    2013-01-01

    When cell cycle withdrawal accompanies terminal differentiation, biosynthesis and cellular growth are likely to change also. In this study, nucleolus size was monitored during cell fate specification in the Drosophila eye imaginal disc using fibrillarin antibody labeling. Nucleolus size is an indicator of ribosome biogenesis and can correlate with cellular growth rate. Nucleolar size was reduced significantly during cell fate specification and differentiation, predominantly as eye disc cells entered a cell cycle arrest that preceded cell fate specification. This reduction in nucleolus size required Dpp and Hh signaling. A transient enlargement of the nucleolus accompanied cell division in the Second Mitotic Wave. Nucleoli continued to diminish in postmitotic cells following fate specification. These results suggest that cellular growth is regulated early in the transition from proliferating progenitor cells to terminal cell fate specification, contemporary with regulation of the cell cycle, and requiring the same extracellular signals.

  14. Size effects in foams : Experiments and modeling

    NARCIS (Netherlands)

    Tekoglu, C.; Gibson, L. J.; Pardoen, T.; Onck, P. R.

    Mechanical properties of cellular solids depend on the ratio of the sample size to the cell size at length scales where the two are of the same order of magnitude. Considering that the cell size of many cellular solids used in engineering applications is between 1 and 10 mm, it is not uncommon to

  15. Size Controlled CaF2 Nanocubes and Their Dosimetric Properties Using Photoluminescence Technique

    Directory of Open Access Journals (Sweden)

    Najlaa D. Alharbi

    2015-01-01

    Full Text Available A new synthetic chemical coprecipitation route for the preparation of well-crystallized size controlled nano- and microcrystalline cubes of CaF2 is reported. Crystalline cubes in the range of 2 μm–20 nm could be synthesized and their sizes were controlled by varying the solvent : cosolvent ratio. The as-synthesized CaF2 nanocubes were characterized by different techniques. Photoluminescence (PL emission spectrum of CaF2 nanocrystalline powder showed strong emission band at 415 nm. Moreover, the effect of Eu as a dopant on the emission spectrum of CaF2 was investigated. This dopant was found to get incorporated in its Eu2+ and Eu3+ forms. The as-produced nanocubes were exposed to UV irradiation and the corresponding PL emission was studied. Excellent results are obtained, where CaF2:Eu nanocubes were found to be highly sensitive and might be suitable for esteeming the doses of UV irradiation using the PL technique.

  16. Optimal control of a repowered vehicle: Plug-in fuel cell against plug-in hybrid electric powertrain

    Energy Technology Data Exchange (ETDEWEB)

    Tribioli, L., E-mail: laura.tribioli@unicusano.it; Cozzolino, R. [Dept. of Industrial Engineering, University of Rome Niccolo’ Cusano (Italy); Barbieri, M. [Engineering Dept., University of Naples Parthenope, Centro Direzionale-Isola C4, 80143 Naples (Italy)

    2015-03-10

    This paper describes two different powertrain configurations for the repowering of a conventional vehicle, equipped with an internal combustion engine (ICE). A model of a mid-sized ICE-vehicle is realized and then modified to model both a parallel plug-in hybrid electric powertrain and a proton electrolyte membrane (PEM) fuel cell (FC) hybrid powertrain. The vehicle behavior under the application of an optimal control algorithm for the energy management is analyzed for the different scenarios and results are compared.

  17. Optimal control of a repowered vehicle: Plug-in fuel cell against plug-in hybrid electric powertrain

    International Nuclear Information System (INIS)

    Tribioli, L.; Cozzolino, R.; Barbieri, M.

    2015-01-01

    This paper describes two different powertrain configurations for the repowering of a conventional vehicle, equipped with an internal combustion engine (ICE). A model of a mid-sized ICE-vehicle is realized and then modified to model both a parallel plug-in hybrid electric powertrain and a proton electrolyte membrane (PEM) fuel cell (FC) hybrid powertrain. The vehicle behavior under the application of an optimal control algorithm for the energy management is analyzed for the different scenarios and results are compared

  18. Size-controlled synthesis of SnO2 quantum dots and their gas-sensing performance

    Science.gov (United States)

    Du, Jianping; Zhao, Ruihua; Xie, Yajuan; Li, Jinping

    2015-08-01

    Tin dioxide quantum dots (TQDs) with controllable size were synthesized by changing the amount of alkaline reagent in the hydrothermal process. The gas-sensing properties were investigated by operating chemoresistor type sensor. The morphology and structure were characterized by X-ray diffraction, scanning/transmission electron microscopy, UV-vis and Raman spectrometry. The as-synthesized SnO2 shows the characteristics of quantum dots and the narrowest size distribution is about 2-3 nm. The gas-sensing results indicate that the responses are strongly dependent on the size of quantum dots. TQDs with different sizes exhibit different sensitivities and selectivities to volatile toxic chemicals such as aldehyde, acetone, methanol, ethanol and amine. Especially, when the sensors are exposed to 100 ppm triethylamine (TEA), the sensing response value of TQDs with small size is two times higher than that of the large-size TQDs. The maximum response values of TQDs to 1 ppm and 100 ppm TEA are 15 and 153, respectively. The response time is 1 s and the recovery time is 47 s upon exposure to 1 ppm TEA. The results suggest that it is an effective method by regulating the size of SnO2 quantum dots to detect low-concentration hazardous volatile compounds.

  19. Size-dependent internalisation of folate-decorated nanoparticles via the pathways of clathrin and caveolae-mediated endocytosis in ARPE-19 cells.

    Science.gov (United States)

    Langston Suen, Wai-Leung; Chau, Ying

    2014-04-01

    We aim to quantify the effect of size and degree of folate loading of folate-decorated polymeric nanoparticles (NPs) on the kinetics of cellular uptake and the selection of endocytic pathways in retinal pigment epithelium (RPE) cells. In this study, methoxy-poly(ethylene glycol)-b-polycaprolactone (mPEG-b-PCL) and folate-functionalized PEG-b-PCL were synthesized for assembling into nanoparticles with sizes ranging from 50 nm to 250 nm. These nanoparticles were internalized into ARPE-19 (human RPE cell line) via receptor-mediated endocytosis. A two-step endocytosis process mathematical model was adopted to quantify binding affinity and uptake kinetics of nanoparticles in RPE cells in uptake and inhibition studies. Nanoparticles with 100% folate loading have highest binding affinity and uptake rate in RPE cells. Maximum uptake rate (Vmax) of nanoparticles increased as the size of particles decreased from 250 nm to 50 nm. Endocytic pathway study was studied by using chlorpromazine and methyl-β-cyclodextran (MβCD), which are clathrin- and caveolae-mediated endocytosis inhibitors, respectively. Both chlorpromazine and MβCD inhibited the uptake of folate-decorated nanoparticles. Inhibition constant (Ki) and maximum uptake rate (Vmax) revealed that 50 nm and 120 nm folate-decorated nanoparticles were found to be internalized via both clathrin- and caveolae-mediated endocytosis. The 250 nm folate-decorated nanoparticles, however, were only internalized via caveolae-mediated pathway. Increased uptake rate of folate-decorated NPs into RPE cells is observed with increasing degree of folate modification. These NPs utilize both clathrin- and caveolae-mediated receptor-mediated endocytosis pathways to enter RPE cells upon size variation. The 50 nm NPs are internalized the fastest, with clathrin-mediated endocytosis as the preferred route. Uptake of 250 nm particles is the slowest and is dominated by caveolae-mediated endocytosis. © 2013 Royal Pharmaceutical

  20. Control of differentiation of melanoma cells

    International Nuclear Information System (INIS)

    Eguchi, Goro

    1980-01-01

    To develop the method to induce the appearance of differentiation in amelanotic melanoma, experimental control of differentiation in B-16 melanoma cells of mice was discussed. Human melanoma cells and yellow melanin pigment cells useful for a fundamental study of radiotherapy for cancer were cultured and were differentiated into some lines. Melanotic B-16 cells and amelanotic B-16 cells were irradiated with thermal neutron (neutron: 2.7 x 10 12 , γ-dose: 32.3 rad) after they were cultured in culture solution containing 10 γ/ml of 10 B-dopa for 13 hours. A fine structure 5 hours after the irradiation in one of 5 experimental cases showed aggregated disintegration of melanin pigment particles, markedly deformed and fragmentized nucleus, and structural changes in cell membrane. (Tsunoda, M.)

  1. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae, E-mail: nicolae.leopold@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics (Romania)

    2014-12-15

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl{sub 4} by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of ∼20 and ∼120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4–8 and 10–30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV–Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  2. EGFR-TK inhibition before radiotherapy reduces tumour volume but does not improve local control: Differential response of cancer stem cells and nontumourigenic cells?

    International Nuclear Information System (INIS)

    Krause, Mechthild; Prager, Jenny; Zhou Xuanjing; Yaromina, Ala; Doerfler, Annegret; Eicheler, Wolfgang; Baumann, Michael

    2007-01-01

    Background and purpose: Waiting times before radiotherapy may reduce tumour control probability due to proliferation of tumour cells. The aim of the experiment was to test whether the growth inhibiting effect of epidermal growth factor receptor (EGFR)-inhibitors after surgery or tumour transplantation results in a lower tumour mass at time of irradiation and can thereby improve local tumour control. Materials and methods: The EGFR-tyrosine kinase inhibitor BIBX1382BS was applied over 14 days starting from microscopically non-in-sano-resection of FaDu tumours or from tumour transplantation, followed by irradiation (5f/5d). Endpoint was local tumour control. In addition, vital tumour areas, pimonidazole hypoxic fraction, BrdU labelling index, and colony forming ability in vitro were tested in control tumours and after BIBX1382BS treatment (starting from transplantation). Results: The tumour volume at start of irradiation was significantly lower in the BIBX1382BS treated tumours as compared to the control groups by factors of 11 (post-surgery setting) and 2.7 (transplantation setting). However, the reduced volume did not translate into improved local control after irradiation. The TCD 50 values after surgery were 25.4 Gy [95% CI 18; 33 Gy] in the control group and 30.5 Gy [24; 37] in the BIBX1382BS group (p = 0.25). Treatment after transplantation resulted in TCD 50 values of 41.1 Gy [35; 47] in the control group and 41.1 Gy [33; 49] in the BIBX1382BS group (p = 1). While the proportion of S-phase cells decreased after BIBX1382BS treatment, no differences were observed between the pimonidazole hypoxic fractions and in vitro colony forming ability. Conclusions: EGFR-TK inhibition with BIBX1382BS over 14 days between macroscopically complete tumour resection or tumour transplantation and start of radiotherapy significantly reduced tumour volume but did not improve local tumour control. One possible explanation is that the EGFR-TK inhibitor has a higher activity in

  3. Cytoplasmic streaming velocity as a plant size determinant.

    Science.gov (United States)

    Tominaga, Motoki; Kimura, Atsushi; Yokota, Etsuo; Haraguchi, Takeshi; Shimmen, Teruo; Yamamoto, Keiichi; Nakano, Akihiko; Ito, Kohji

    2013-11-11

    Cytoplasmic streaming is active transport widely occurring in plant cells ranging from algae to angiosperms. Although it has been revealed that cytoplasmic streaming is generated by organelle-associated myosin XI moving along actin bundles, the fundamental function in plants remains unclear. We generated high- and low-speed chimeric myosin XI by replacing the motor domains of Arabidopsis thaliana myosin XI-2 with those of Chara corallina myosin XI and Homo sapiens myosin Vb, respectively. Surprisingly, the plant sizes of the transgenic Arabidopsis expressing high- and low-speed chimeric myosin XI-2 were larger and smaller, respectively, than that of the wild-type plant. This size change correlated with acceleration and deceleration, respectively, of cytoplasmic streaming. Our results strongly suggest that cytoplasmic streaming is a key determinant of plant size. Furthermore, because cytoplasmic streaming is a common system for intracellular transport in plants, our system could have applications in artificial size control in plants. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Planar Cell Polarity Controls Pancreatic Beta Cell Differentiation and Glucose Homeostasis

    DEFF Research Database (Denmark)

    Cortijo, Cedric; Gouzi, Mathieu; Tissir, Fadel

    2012-01-01

    glucose clearance. Loss of Celsr2 and 3 leads to a reduction of Jun phosphorylation in progenitors, which, in turn, reduces beta cell differentiation from endocrine progenitors. These results highlight the importance of the PCP pathway in cell differentiation in vertebrates. In addition, they reveal.......5 synchronously to apicobasal polarization of pancreas progenitors. Loss of function of the two PCP core components Celsr2 and Celsr3 shows that they control the differentiation of endocrine cells from polarized progenitors, with a prevalent effect on insulin-producing beta cells. This results in a decreased...

  5. Size-controlled one-pot synthesis of fluorescent cadmium sulfide semiconductor nanoparticles in an apoferritin cavity

    International Nuclear Information System (INIS)

    Iwahori, K; Yamashita, I

    2008-01-01

    A simple size-controlled synthesis of cadmium sulfide (CdS) nanoparticle (NP) cores in the cavity of apoferritin from horse spleen (HsAFr) was performed by a slow chemical reaction synthesis and a two-step synthesis protocol. We found that the CdS NP core synthesis was slow and that premature CdS NP cores were formed in the apoferritin cavity when the concentration of ammonia water was low. It was proven that the control of the ammonia water concentration can govern the CdS NP core synthesis and successfully produce size-controlled CdS NP cores with diameters from 4.7 to 7.1 nm with narrow size dispersion. X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy (HR-TEM) observation characterized the CdS NP cores obtained as cubic polycrystalline NPs, which showed photoluminescence with red shifts depending on their diameters. From the research of CdS NP core synthesis in the recombinant apoferritins, the zeta potential of apoferritin is important for the biomineralization of CdS NP cores in the apoferritin cavity. These synthesized CdS NPs with different photoluminescence properties will be applicable in a wide variety of nano-applications.

  6. Hierarchical TiO{sub 2} submicron-sized spheres for enhanced power conversion efficiency in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-10-15

    Hierarchical TiO{sub 2} submicron-sized sphere scattering layer, with relatively large surface area and effective light scattering, shows enhanced power conversion efficiency in dye-sensitized solar cells. - Highlights: • Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized. • The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. • DSC exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS (2.00%) photoanodes. - Abstract: Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized by a facile one-step solvothermal method in ethanol solvent. The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. When applied as the scattering overlayer in dye-sensitized solar cells (DSCs), such TiO{sub 2} HSSs effectively improved light harvesting and led to the increase of photocurrent in DSCs. Furthermore, bilayer-structured photoanode also provided fast electron transportation and long electron lifetime as confirmed by electrochemical impedance spectra. As a result, DSC based on P25 nanoparticle underlayer and HSS-2 overlayer exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS-2 (2.00%) photoanodes.

  7. Lead, zinc and copper fine powder with controlled size and shape

    Directory of Open Access Journals (Sweden)

    Mahmoud A Rabah

    2017-12-01

    Full Text Available This study describes the preparation of lead, zinc and copper powders by hydrometallurgy from secondary resources. Chloride, sulphate and acetate salts of zinc, copper and lead were prepared. The powders were prepared by reducing the ionic species of these metals by hydrazine hydrate or ascorbic acid. The effect of addition of some water soluble polar organic solvents to the aqueous salt solutions on the morphology and particle size of the prepared powder was studied. Findings were explained on the basis of the transition state theory and according to the Hughes and Ingold’s rule. Aqueous solutions alone produce metal powder having different size and irregular shape. The presence of polar organic solvents with high molecular weight and polarity produce powders having controlled size and regular morphology. The reason was because solvent polarity enhances the rate of red-ox reactions between metal ions and the reducing agent. The mean particle size of the powder was 60 um with zinc, 80 um with copper, and 90 um with lead. The extent of productivity was ≥98%. Results highlighted that the chemical reduction of the ionic species took place in a sequence steps. The first is a diffusion of the reactants across a boundary layer established at the polar site of the organic solvent molecules. The next step is the direct contact of the reactants. The third step involved reduction to yield powder. The last is the backward diffusion of the powder outside the boundary layer. Results showed that addition of water-miscible solvents having high dielectric constant increased the polarity of the medium. This energizes and enhances the one or more t step of the model to be more rapid to yield particles with small size and symmetrical shape.

  8. Effects of cell size and macrosegregation on the corrosion behavior of a dilute Pb-Sb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Daniel M.; Spinelli, Jose E.; Osorio, Wislei R.; Garcia, Amauri [Department of Materials Engineering, State University of Campinas-UNICAMP, P.O. Box 6122, 13083-970 Campinas, Sao Paulo (Brazil)

    2006-11-08

    The aim of this study was to examine the effect of cooling rate on the cellular growth of a Pb-0.85wt%Sb alloy and to evaluate the influences of cell size and of the corresponding macrosegregation profile on the resultant corrosion behavior. In order to obtain the as-cast samples a water-cooled unidirectional solidification system was used. Such experimental set-up has permitted the development of a clear cellular structural array even for relative high cooling rates and has allowed a wide range of solidification conditions to be analyzed. Macrostructural and microstructural aspects along the casting were characterized by optical microscopy and scanning electron microscope (SEM) techniques. The electrochemical impedance spectroscopy technique and potentiodynamic curves (Tafel extrapolation) were used to analyze the corrosion resistance of samples collected along the casting length and immersed in a 0.5M H{sub 2}SO{sub 4} solution at 25{sup o}C. It was found that the corrosion rate decreases with increasing cell spacing and that the pre-programming of microstructure cell size can be used as an alternative way to produce as-cast components of Pb-Sb alloys, such as battery grids, with better corrosion resistance. (author)

  9. ATX-2, the C. elegans Ortholog of Human Ataxin-2, Regulates Centrosome Size and Microtubule Dynamics.

    Directory of Open Access Journals (Sweden)

    Michael D Stubenvoll

    2016-09-01

    Full Text Available Centrosomes are critical sites for orchestrating microtubule dynamics, and exhibit dynamic changes in size during the cell cycle. As cells progress to mitosis, centrosomes recruit more microtubules (MT to form mitotic bipolar spindles that ensure proper chromosome segregation. We report a new role for ATX-2, a C. elegans ortholog of Human Ataxin-2, in regulating centrosome size and MT dynamics. ATX-2, an RNA-binding protein, forms a complex with SZY-20 in an RNA-independent fashion. Depleting ATX-2 results in embryonic lethality and cytokinesis failure, and restores centrosome duplication to zyg-1 mutants. In this pathway, SZY-20 promotes ATX-2 abundance, which inversely correlates with centrosome size. Centrosomes depleted of ATX-2 exhibit elevated levels of centrosome factors (ZYG-1, SPD-5, γ-Tubulin, increasing MT nucleating activity but impeding MT growth. We show that ATX-2 influences MT behavior through γ-Tubulin at the centrosome. Our data suggest that RNA-binding proteins play an active role in controlling MT dynamics and provide insight into the control of proper centrosome size and MT dynamics.

  10. Analysis of human blood plasma cell-free DNA fragment size distribution using EvaGreen chemistry based droplet digital PCR assays.

    Science.gov (United States)

    Fernando, M Rohan; Jiang, Chao; Krzyzanowski, Gary D; Ryan, Wayne L

    2018-04-12

    Plasma cell-free DNA (cfDNA) fragment size distribution provides important information required for diagnostic assay development. We have developed and optimized droplet digital PCR (ddPCR) assays that quantify short and long DNA fragments. These assays were used to analyze plasma cfDNA fragment size distribution in human blood. Assays were designed to amplify 76,135, 490 and 905 base pair fragments of human β-actin gene. These assays were used for fragment size analysis of plasma cell-free, exosome and apoptotic body DNA obtained from normal and pregnant donors. The relative percentages for 76, 135, 490 and 905 bp fragments from non-pregnant plasma and exosome DNA were 100%, 39%, 18%, 5.6% and 100%, 40%, 18%,3.3%, respectively. The relative percentages for pregnant plasma and exosome DNA were 100%, 34%, 14%, 23%, and 100%, 30%, 12%, 18%, respectively. The relative percentages for non-pregnant plasma pellet (obtained after 2nd centrifugation step) were 100%, 100%, 87% and 83%, respectively. Non-pregnant Plasma cell-free and exosome DNA share a unique fragment distribution pattern which is different from pregnant donor plasma and exosome DNA fragment distribution indicating the effect of physiological status on cfDNA fragment size distribution. Fragment distribution pattern for plasma pellet that includes apoptotic bodies and nuclear DNA was greatly different from plasma cell-free and exosome DNA. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  11. Crystal structure mediates mode of cell death in TiO2 nanotoxicity

    International Nuclear Information System (INIS)

    Braydich-Stolle, Laura K.; Schaeublin, Nicole M.; Murdock, Richard C.; Jiang, Jingkun; Biswas, Pratim; Schlager, John J.; Hussain, Saber M.

    2009-01-01

    Certain properties that nanoparticles possess differentiate them from their bulk counterparts, and these characteristics must be evaluated prior to nanoparticle studies and include: size, shape, dispersion, physical and chemical properties, surface area, and surface chemistry. Early nanotoxicity studies evaluating TiO 2 have yielded conflicting data which identify either size or crystal structure as the mediating property for nano-TiO 2 toxicity. However, it is important to note that none of these studies examined size with the crystal structure composition controlled for or examined crystal structure while controlling the nanoparticle size. The goal of this study was to evaluate the role of size and crystal structure in TiO 2 nanotoxicity while controlling for as many other nanoproperties as possible using the HEL-30 mouse keratinocyte cell line as a model for dermal exposure. In the size-dependent studies, all the nanoparticles are 100% anatase, and aggregate sizes were determined in order to take into account the effect of agglomeration on size-dependent toxicity. In addition, varying crystal structures were assessed while the size of the nanoparticles was controlled. We were able to identify that both size and crystal structure contribute to cytotoxicity and that the mechanism of cell death varies based on crystal structure. The 100% anatase TiO 2 nanoparticles, regardless of size, induced cell necrosis, while the rutile TiO 2 nanoparticles initiated apoptosis through formation of reactive oxygen species (ROS).

  12. Sub-10 nm Platinum Nanocrystals with Size and Shape Control: Catalytic Study for Ethylene and Pyrrole Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Tsung, Chia-Kuang; Kuhn, John N.; Huang, Wenyu; Aliaga, Cesar; Hung, Ling-I; Somorjai, Gabor A.; Yang, Peidong

    2009-03-02

    Platinum nanocubes and nanopolyhedra with tunable size from 5 to 9 nm were synthesized by controlling the reducing rate of metal precursor ions in a one-pot polyol synthesis. A two-stage process is proposed for the simultaneous control of size and shape. In the first stage, the oxidation state of the metal ion precursors determined the nucleation rate and consequently the number of nuclei. The reaction temperature controlled the shape in the second stage by regulation of the growth kinetics. These well-defined nanocrystals were loaded into MCF-17 mesoporous silica for examination of catalytic properties. Pt loadings and dispersions of the supported catalysts were determined by elemental analysis (ICP-MS) and H2 chemisorption isotherms, respectively. Ethylene hydrogenation rates over the Pt nanocrystals were independent of both size and shape and comparable to Pt single crystals. For pyrrole hydrogenation, the nanocubes enhanced ring-opening ability and thus showed a higher selectivity to n-butylamine as compared to nanopolyhedra.

  13. Hematopoietic stem cell fate through metabolic control.

    Science.gov (United States)

    Ito, Kyoko; Ito, Keisuke

    2018-05-25

    Hematopoietic stem cells (HSCs) maintain a quiescent state in the bone marrow to preserve their self-renewal capacity, but also undergo cell divisions as required. Organelles such as the mitochondria sustain cumulative damage during these cell divisions, and this damage may eventually compromise the cells' self-renewal capacity. HSC divisions result in either self-renewal or differentiation, with the balance between the two directly impacting hematopoietic homeostasis; but the heterogeneity of available HSC-enriched fractions, together with the technical challenges of observing HSC behavior, has long hindered the analysis of individual HSCs, and prevented the elucidation of this process. However, recent advances in genetic models, metabolomics analyses and single-cell approaches have revealed the contributions made to HSC self-renewal by metabolic cues, mitochondrial biogenesis, and autophagy/mitophagy, which have highlighted mitochondrial quality as a key control factor in the equilibrium of HSCs. A deeper understanding of precisely how specific modes of metabolism control HSC fate at the single cell level is therefore not only of great biological interest, but will have clear clinical implications for the development of therapies for hematological disease. Copyright © 2018. Published by Elsevier Inc.

  14. Effects of grain size on the corrosion resistance of pure magnesium by cooling rate-controlled solidification

    Science.gov (United States)

    Liu, Yichi; Liu, Debao; You, Chen; Chen, Minfang

    2015-09-01

    The aim of this study was to investigate the effect of grain size on the corrosion resistance of pure magnesium developed for biomedical applications. High-purity magnesium samples with different grain size were prepared by the cooling rate-controlled solidification. Electrochemical and immersion tests were employed to measure the corrosion resistance of pure magnesium with different grain size. The electrochemical polarization curves indicated that the corrosion susceptibility increased as the grain size decrease. However, the electrochemical impedance spectroscopy (EIS) and immersion tests indicated that the corrosion resistance of pure magnesium is improved as the grain size decreases. The improvement in the corrosion resistance is attributed to refine grain can produce more uniform and density film on the surface of sample.

  15. Ultrastructural morphometry of parotid acinar cells following fractionated irradiation

    International Nuclear Information System (INIS)

    Grehn, A.-L.; Gustafsson, H.; Franzen, L.; Thornell, L.-E.; Henriksson, R.

    1997-01-01

    The aim of this study was to evaluate the long term effects on the ultrastructure of parotid glands after fractionated irradiation. The method implemented involved 5 x 6 Gy and 5 x 8 Gy, Monday to Friday 6 MV photons. By unilateral irradiation, the contralateral parotid gland served as a control. Although irradiation diminished the acinar cell density in light microscopic sections from 75 to 32% after 5 x 8 Gy of irradiation, ultrastructural morphometry could not detect any statistically significant differences in acinar cell size, nuclear size, nuclear density, granule area, mean granule size, or granule density. In general, greater differences were seen between rats receiving 30 or 40 Gy, on both the irradiated and the control side, than between the irradiated side and the control side. This was interpreted as due to differences in the nutritional state of the animals. This analysis concluded that individual acinar cells that survive irradiation seem not to be damaged in the long term when evaluated at the ultrastructural level. The study further stresses the importance of adequate sampling sizes and the use of adequate controls. (author)

  16. Fast electric control of the droplet size in a microfluidic T-junction droplet generator

    Science.gov (United States)

    Shojaeian, Mostafa; Hardt, Steffen

    2018-05-01

    The effect of DC electric fields on the generation of droplets of water and xanthan gum solutions in sunflower oil at a microfluidic T-junction is experimentally studied. The electric field leads to a significant reduction of the droplet diameter, by about a factor of 2 in the case of water droplets. The droplet size can be tuned by varying the electric field strength, an effect that can be employed to produce a stream of droplets with a tailor-made size sequence. Compared to the case of purely hydrodynamic droplet production without electric fields, the electric control has about the same effect on the droplet size if the electric stress at the liquid/liquid interface is the same as the hydrodynamic stress.

  17. Driving an Industry: Medium and Heavy Duty Fuel Cell Electric Truck Component Sizing

    OpenAIRE

    Marcinkoski, J.; Vijayagopal, R.; Kast, J.; Duran, A.

    2016-01-01

    Medium and heavy duty (MD and HD respectively) vehicles are responsible for 26 percent of the total U.S. transportation petroleum consumption [1]. Hydrogen fuel cells have demonstrated value as part of a portfolio of strategies for reducing petroleum use and emissions from MD and HD vehicles [2] [3], but their performance and range capabilities, and associated component sizing remain less clear when compared to other powertrains. This paper examines the suitability of converting a representat...

  18. Stable Regulation of Cell Cycle Events in Mycobacteria: Insights From Inherently Heterogeneous Bacterial Populations.

    Science.gov (United States)

    Logsdon, Michelle M; Aldridge, Bree B

    2018-01-01

    Model bacteria, such as E. coli and B. subtilis , tightly regulate cell cycle progression to achieve consistent cell size distributions and replication dynamics. Many of the hallmark features of these model bacteria, including lateral cell wall elongation and symmetric growth and division, do not occur in mycobacteria. Instead, mycobacterial growth is characterized by asymmetric polar growth and division. This innate asymmetry creates unequal birth sizes and growth rates for daughter cells with each division, generating a phenotypically heterogeneous population. Although the asymmetric growth patterns of mycobacteria lead to a larger variation in birth size than typically seen in model bacterial populations, the cell size distribution is stable over time. Here, we review the cellular mechanisms of growth, division, and cell cycle progression in mycobacteria in the face of asymmetry and inherent heterogeneity. These processes coalesce to control cell size. Although Mycobacterium smegmatis and Mycobacterium bovis Bacillus Calmette-Guérin (BCG) utilize a novel model of cell size control, they are similar to previously studied bacteria in that initiation of DNA replication is a key checkpoint for cell division. We compare the regulation of DNA replication initiation and strategies used for cell size homeostasis in mycobacteria and model bacteria. Finally, we review the importance of cellular organization and chromosome segregation relating to the physiology of mycobacteria and consider how new frameworks could be applied across the wide spectrum of bacterial diversity.

  19. Rac1 Regulates the Activity of mTORC1 and mTORC2 and Controls Cellular Size

    Science.gov (United States)

    Saci, Abdelhafid; Cantley, Lewis C.; Carpenter, Christopher L.

    2013-01-01

    SUMMARY Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that exists in two separate complexes, mTORC1 and mTORC2, that function to control cell size and growth in response to growth factors, nutrients, and cellular energy levels. Low molecular weight GTP-binding proteins of the Rheb and Rag families are key regulators of the mTORC1 complex, but regulation of mTORC2 is poorly understood. Here, we report that Rac1, a member of the Rho family of GTPases, is a critical regulator of both mTORC1 and mTORC2 in response to growth-factor stimulation. Deletion of Rac1 in primary cells using an inducible-Cre/Lox approach inhibits basal and growth-factor activation of both mTORC1 and mTORC2. Rac1 appears to bind directly to mTOR and to mediate mTORC1 and mTORC2 localization at specific membranes. Binding of Rac1 to mTOR does not depend on the GTP-bound state of Rac1, but on the integrity of its C-terminal domain. This function of Rac1 provides a means to regulate mTORC1 and mTORC2 simultaneously. PMID:21474067

  20. Size-controlled synthesis of transition metal nanoparticles through chemical and photo-chemical routes

    Science.gov (United States)

    Tangeysh, Behzad

    The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 +/-0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 +/-0.2nm) and copper nanoparticles (1.5 +/-0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of