WorldWideScience

Sample records for total nucleated cell

  1. Plerixafor mobilization leads to a lower ratio of CD34+ cells to total nucleated cells which results in greater storage costs.

    Science.gov (United States)

    Tanhehco, Yvette C; Adamski, Jill; Sell, Mary; Cunningham, Kathleen; Eisenmann, Christa; Magee, Deborah; Stadtmauer, Edward A; O'Doherty, Una

    2010-01-01

    Plerixafor (Mozobil, AMD3100) with granulocyte-colony stimulating factor (G-CSF) mobilizes more CD34+ cells/kg compared to G-CSF alone. Given that plerixafor enhances mobilization of multiple white blood cell lineages, we determined if more storage space is required for products collected from patients mobilized with plerixafor. A review of the medical records of 15 patients mobilized with chemotherapy and G-CSF (control) and 14 patients mobilized with plerixafor plus G-CSF (plerixafor) was performed. Data on demographics, baseline characteristics, CD34+ cells/kg, total nucleated cells, total mononuclear cells, total apheresis sessions, and total bags for storage were collected. Mean values were determined and compared using Student's t-test. We found that the proportion of CD34+ cells among total nucleated cells was less in the plerixafor group compared to the control group (P = 0.0427). More nucleated cells (10.7 x 10(10) vs. 7.1 x 10(10), P =0.0452) and mononuclear cells (9.7 x 10(10) vs. 5.9 x 10(10), P = 0.0059) were mobilized with plerixafor plus G-CSF. However, there was no significant difference in CD34+ cells/kg, total CD34+ cells or the proportion of mononuclear cells among total nucleated cells between the two groups. More storage bags were required for the plerixafor group compared to the control group (15 vs. 9, P = 0.0299). Mobilization with plerixafor plus G-CSF resulted in a smaller proportion of CD34+ cells collected and a greater number of storage bags. An increase in the number of bags required for stem cell storage may be logistically problematic and will also lead to increased costs for storage of stem cells.

  2. A new strategy for umbilical cord blood collection developed at the first Colombian public cord blood bank increases total nucleated cell content.

    Science.gov (United States)

    Vanegas, Diana; Triviño, Lady; Galindo, Cristian; Franco, Leidy; Salguero, Gustavo; Camacho, Bernardo; Perdomo-Arciniegas, Ana-María

    2017-09-01

    The total nucleated cell dosage of umbilical cord blood (UCB) is an important factor in determining successful allogeneic hematopoietic stem cell transplantation after a minimum human leukocyte antigen donor-recipient match. The northern South American population is in need of a new-generation cord blood bank that cryopreserves only units with high total nucleated cell content, thereby increasing the likelihood of use. Colombia set up a public cord blood bank in 2014; and, as a result of its research for improving high total nucleated cell content, a new strategy for UCB collection was developed. Data from 2933 collected and 759 cryopreserved cord blood units between 2014 and 2015 were analyzed. The correlation of donor and collection variables with cellularity was evaluated. Moreover, blood volume, cell content, CD34+ count, clonogenic capacity, and microbial contamination were assessed comparing the new method, which combines in utero and ex utero techniques, with the conventional strategies. Multivariate analysis confirmed a correlation between neonatal birth weight and cell content. The new collection method increased total nucleated cell content in approximately 26% and did not alter pre-cryopreservation and post-thaw cell recovery, viability, or clonogenic ability. Furthermore, it showed a remarkably low microbial contamination rate (1.2%). The strategy for UCB collection developed at the first Colombian public cord blood bank increases total nucleated cell content and does not affect unit quality. The existence of this bank is a remarkable breakthrough for Latin-American patients in need of this kind of transplantation. © 2017 The Authors Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.

  3. High diagnostic accuracy of the Sysmex XT-2000iV delta total nucleated cells on effusions for feline infectious peritonitis.

    Science.gov (United States)

    Giordano, Alessia; Stranieri, Angelica; Rossi, Gabriele; Paltrinieri, Saverio

    2015-06-01

    The ΔWBC (the ratio between DIFF and BASO counts of the Sysmex XT-2000iV), hereafter defined as ΔTNC (total nucleated cells), is high in effusions due to feline infectious peritonitis (FIP), as cells are entrapped in fibrin clots formed in the BASO reagent. Similar clots form in the Rivalta's test, a method with high diagnostic accuracy for FIP. The objective of this study was to determine the diagnostic accuracy for FIP and the optimal cutoff of ΔTNC. After a retrospective search of our database, DIFF and BASO counts, and the ΔTNC from cats with and without FIP were compared to each other. Sensitivity, specificity, and positive and negative likelihood ratios (LR+, LR-) were calculated. A ROC curve was designed to determine the cutoff for best sensitivity and specificity. Effusions from 20 FIP and 31 non-FIP cats were analyzed. The ΔTNC was higher (P  2.5 had 100% specificity. The ΔTNC has a high diagnostic accuracy for FIP-related effusions by providing an estimate of precipitable proteins, as the Rivalta's test, in addition to the cell count. As fibrin clots result in false lower BASO counts, the ΔTNC is preferable to the WBC count generated by the BASO channel alone in suspected FIP effusions. © 2015 American Society for Veterinary Clinical Pathology.

  4. A nucleation theory of cell surface capping

    International Nuclear Information System (INIS)

    Coutsias, E.A.; Wester, M.J.; Perelson, A.S.

    1997-01-01

    We propose a new theory of cell surface capping based on the principles of nucleation. When antibody interacts with cell surface molecules, the molecules initially form small aggregates called patches that later coalesce into a large aggregate called a cap. While a cap can form by patches being pulled together by action of the cell''s cytoskeleton, in the case of some molecules, disruption of the cytoskeleton does not prevent cap formation. Diffusion of large aggregates on a cell surface is slow, and thus we propose that a cap can form solely through the diffusion of small aggregates containing just one or a few cell surface molecules. Here we consider the extreme case in which single molecules are mobile, but aggregates of all larger sizes are immobile. We show that a set of patches in equilibrium with a open-quotes seaclose quotes of free cell surface molecules can undergo a nucleation-type phase transition in which the largest patch will bind free cell surface molecules, deplete the concentration of such molecules in the open-quotes seaclose quotes and thus cause the other patches to shrink in size. We therefore show that a cap can form without patches having to move, collide with each other, and aggregate

  5. Total Sulfate vs. Sulfuric Acid Monomer Concenterations in Nucleation Studies.

    Czech Academy of Sciences Publication Activity Database

    Neitola, K.; Brus, David; Makkonen, U.; Sipilä, M.; Mauldin III, R.L.; Sarnela, N.; Jokinen, T.; Lihavainen, H.; Kulmala, M.

    2015-01-01

    Roč. 15, č. 6 (2015), s. 3429-3443 ISSN 1680-7316 Grant - others:AFCE(FI) 1118615 Institutional support: RVO:67985858 Keywords : ion-induced nucleation * particle formation * experimental setup Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.114, year: 2015

  6. Human papillomavirus 16 E5 induces bi-nucleated cell formation by cell-cell fusion

    International Nuclear Information System (INIS)

    Hu Lulin; Plafker, Kendra; Vorozhko, Valeriya; Zuna, Rosemary E.; Hanigan, Marie H.; Gorbsky, Gary J.; Plafker, Scott M.; Angeletti, Peter C.; Ceresa, Brian P.

    2009-01-01

    Human papillomaviruses (HPV) 16 is a DNA virus encoding three oncogenes - E5, E6, and E7. The E6 and E7 proteins have well-established roles as inhibitors of tumor suppression, but the contribution of E5 to malignant transformation is controversial. Using spontaneously immortalized human keratinocytes (HaCaT cells), we demonstrate that expression of HPV16 E5 is necessary and sufficient for the formation of bi-nucleated cells, a common characteristic of precancerous cervical lesions. Expression of E5 from non-carcinogenic HPV6b does not produce bi-nucleate cells. Video microscopy and biochemical analyses reveal that bi-nucleates arise through cell-cell fusion. Although most E5-induced bi-nucleates fail to propagate, co-expression of HPV16 E6/E7 enhances the proliferation of these cells. Expression of HPV16 E6/E7 also increases bi-nucleated cell colony formation. These findings identify a new role for HPV16 E5 and support a model in which complementary roles of the HPV16 oncogenes lead to the induction of carcinogenesis

  7. Neonatal nucleated red blood cells in G6PD deficiency.

    Science.gov (United States)

    Yeruchimovich, Mark; Shapira, Boris; Mimouni, Francis B; Dollberg, Shaul

    2002-05-01

    The objective of this study is to study the absolute number of nucleated red blood cells (RBC) at birth, an index of active fetal erythropoiesis, in infants with G6PD deficiency and in controls. We tested the hypothesis that hematocrit and hemoglobin would be lower, and absolute nucleated RBC counts higher, in the G6PD deficient and that these changes would be more prominent in infants exposed passively to fava bean through maternal diet. Thirty-two term infants with G6PD deficiency were compared with 30 term controls. Complete blood counts with manual differential counts were obtained within 12 hours of life. Absolute nucleated RBC and corrected leukocyte counts were computed from the Coulter results and the differential count. G6PD deficient patients did not differ from controls in terms of gestational age, birth weight, or Apgar scores or in any of the hematologic parameters studied, whether or not the mother reported fava beans consumption in the days prior to delivery. Although intrauterine hemolysis is possible in G6PD deficient fetuses exposed passively to fava beans, our study supports that such events must be very rare.

  8. First passage times in homogeneous nucleation: Dependence on the total number of particles

    International Nuclear Information System (INIS)

    Yvinec, Romain; Bernard, Samuel; Pujo-Menjouet, Laurent; Hingant, Erwan

    2016-01-01

    Motivated by nucleation and molecular aggregation in physical, chemical, and biological settings, we present an extension to a thorough analysis of the stochastic self-assembly of a fixed number of identical particles in a finite volume. We study the statistics of times required for maximal clusters to be completed, starting from a pure-monomeric particle configuration. For finite volumes, we extend previous analytical approaches to the case of arbitrary size-dependent aggregation and fragmentation kinetic rates. For larger volumes, we develop a scaling framework to study the first assembly time behavior as a function of the total quantity of particles. We find that the mean time to first completion of a maximum-sized cluster may have a surprisingly weak dependence on the total number of particles. We highlight how higher statistics (variance, distribution) of the first passage time may nevertheless help to infer key parameters, such as the size of the maximum cluster. Finally, we present a framework to quantify formation of macroscopic sized clusters, which are (asymptotically) very unlikely and occur as a large deviation phenomenon from the mean-field limit. We argue that this framework is suitable to describe phase transition phenomena, as inherent infrequent stochastic processes, in contrast to classical nucleation theory

  9. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    International Nuclear Information System (INIS)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D

    2008-01-01

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH i ) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH i values were dependent on the total surface area of the particulates, indicating that no unique threshold RH i for ice nucleation prevails

  10. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    Energy Technology Data Exchange (ETDEWEB)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D [Department of Chemistry, University of Toronto, 80 St George Street, Toronto, ON, M5S 3H6 (Canada)], E-mail: zkanji@chem.utoronto.ca

    2008-04-15

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH{sub i}) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH{sub i} values were dependent on the total surface area of the particulates, indicating that no unique threshold RH{sub i} for ice nucleation prevails.

  11. Numerical model for the deformation of nucleated cells by optical stretchers

    KAUST Repository

    Sraj, Ihab; Francois, Joshua; Marr, David W M; Eggleton, Charles D.

    2015-01-01

    In this paper, we seek to numerically study the deformation of nucleated cells by single diode-laser bar optical stretchers. We employ a recently developed computational model, the dynamic ray-tracing method, to determine the force distribution

  12. The fate of radiation induced giant-nucleated cells of human skin fibroblasts

    Science.gov (United States)

    Almahwasi, A. A.; Jeynes, J. C.; Bradley, D. A.; Regan, P. H.

    2017-11-01

    Radiation-induced giant-nucleated cells (GCs) have been observed to occur within survivors of irradiated cancerous and within healthy cells, both in vivo and in vitro. The expression of such morphological alterations is associated with genomic instability. This study was designed to investigate the fate of GCs induced in a normal human fibroblast cell line (AG1522) after exposure to 0.2, 1 or 2 Gy of X-ray or proton irradiation. The total of 79 individual AG1522 GCs present at 7, 14 or 21 days after each dose point were analysed from fluorescence microscopy images captured over approximately 120 h. The GCs were identified at the beginning of the observation period for each time point post-irradiation and the area of the cell nucleus was measured (μm2) using a cell-recognition MATLAB code. The results demonstrate that the majority of GCs had undergone a prolonged mitotic arrest, which might be an indication of the survival strategy. The live cell microscopy confirms that a giant-nucleated cell formed 14 days after exposure to 0.2 Gy of proton irradiation was divided into two asymmetrical normal-sized cells. These results suggest that a small fraction of GCs can proliferate and form progeny. Some of GCs had disappeared from the microscopy fields. The rate of their loss was decreased as the dose increased but there remains the potential for them to have progeny that could continue to proliferate, ultimately contributing to development of cancer risk. This important method to access delayed effects in normal tissues could act as a potential radioprotective assay for a dose-limiting parameter when applying radiotherapy. These results might have important implications in evaluating risk estimates for patients during radiation therapy treatment.

  13. Correlation of Solubility with the Metastable Limit of Nucleation Using Gauge-Cell Monte Carlo Simulations.

    Science.gov (United States)

    Clark, Michael D; Morris, Kenneth R; Tomassone, Maria Silvina

    2017-09-12

    We present a novel simulation-based investigation of the nucleation of nanodroplets from solution and from vapor. Nucleation is difficult to measure or model accurately, and predicting when nucleation should occur remains an open problem. Of specific interest is the "metastable limit", the observed concentration at which nucleation occurs spontaneously, which cannot currently be estimated a priori. To investigate the nucleation process, we employ gauge-cell Monte Carlo simulations to target spontaneous nucleation and measure thermodynamic properties of the system at nucleation. Our results reveal a widespread correlation over 5 orders of magnitude of solubilities, in which the metastable limit depends exclusively on solubility and the number density of generated nuclei. This three-way correlation is independent of other parameters, including intermolecular interactions, temperature, molecular structure, system composition, and the structure of the formed nuclei. Our results have great potential to further the prediction of nucleation events using easily measurable solute properties alone and to open new doors for further investigation.

  14. Profilin-Dependent Nucleation and Assembly of Actin Filaments Controls Cell Elongation in Arabidopsis1[OPEN

    Science.gov (United States)

    Cao, Lingyan; Blanchoin, Laurent; Staiger, Christopher J.

    2016-01-01

    Actin filaments in plant cells are incredibly dynamic; they undergo incessant remodeling and assembly or disassembly within seconds. These dynamic events are choreographed by a plethora of actin-binding proteins, but the exact mechanisms are poorly understood. Here, we dissect the contribution of Arabidopsis (Arabidopsis thaliana) PROFILIN1 (PRF1), a conserved actin monomer-binding protein, to actin organization and single filament dynamics during axial cell expansion of living epidermal cells. We found that reduced PRF1 levels enhanced cell and organ growth. Surprisingly, we observed that the overall frequency of nucleation events in prf1 mutants was dramatically decreased and that a subpopulation of actin filaments that assemble at high rates was reduced. To test whether profilin cooperates with plant formin proteins to execute actin nucleation and rapid filament elongation in cells, we used a pharmacological approach. Here, we used Small Molecule Inhibitor of Formin FH2 (SMIFH2), after validating its mode of action on a plant formin in vitro, and observed a reduced nucleation frequency of actin filaments in live cells. Treatment of wild-type epidermal cells with SMIFH2 mimicked the phenotype of prf1 mutants, and the nucleation frequency in prf1-2 mutant was completely insensitive to these treatments. Our data provide compelling evidence that PRF1 coordinates the stochastic dynamic properties of actin filaments by modulating formin-mediated actin nucleation and assembly during plant cell expansion. PMID:26574597

  15. An improved model for nucleation-limited ice formation in living cells during freezing.

    Directory of Open Access Journals (Sweden)

    Jingru Yi

    Full Text Available Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF, our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1. We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN and volume-catalyzed nucleation (VCN. Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.

  16. Light scattering of a Bessel beam by a nucleated biological cell: An eccentric sphere model

    Science.gov (United States)

    Wang, Jia Jie; Han, Yi Ping; Chang, Jiao Yong; Chen, Zhu Yang

    2018-02-01

    Within the framework of generalized Lorenz-Mie theory (GLMT), an eccentrically stratified dielectric sphere model illuminated by an arbitrarily incident Bessel beam is applied to investigate the scattering characteristics of a single nucleated biological cell. The Bessel beam propagating in an arbitrary direction is expanded in terms of vector spherical wave functions (VSWFs), where the beam shape coefficients (BSCs) are calculated rigorously in a closed analytical form. The effects of the half-cone angle of Bessel beam, the location of the particle in the beam, the size ratio of nucleus to cell, and the location of the nucleus inside the cell on the scattering properties of a nucleated cell are analyzed. The results provide useful references for optical diagnostic and imaging of particle having nucleated structure.

  17. Microtubule array reorientation in response to hormones does not involve changes in microtubule nucleation modes at the periclinal cell surface

    Science.gov (United States)

    Atkinson, Samantha; Kirik, Angela; Kirik, Viktor

    2014-01-01

    Aligned microtubule arrays spatially organize cell division, trafficking, and determine the direction of cell expansion in plant cells. In response to changes in environmental and developmental signals, cells reorganize their microtubule arrays into new configurations. Here, we tested the role of microtubule nucleation during hormone-induced microtubule array reorientation. We have found that in the process of microtubule array reorientation the ratios between branching, parallel, and de-novo nucleations remained constant, suggesting that the microtubule reorientation mechanism does not involve changes in nucleation modes. In the ton2/fass mutant, which has reduced microtubule branching nucleation frequency and decreased nucleation activity of the γ-tubulin complexes, microtubule arrays were able to reorient. Presented data suggest that reorientation of microtubules into transverse arrays in response to hormones does not involve changes in microtubule nucleation at the periclinal cell surface PMID:25135522

  18. Multi-nucleate retinal pigment epithelium cells of the human macula exhibit a characteristic and highly specific distribution.

    Science.gov (United States)

    Starnes, Austin C; Huisingh, Carrie; McGwin, Gerald; Sloan, Kenneth R; Ablonczy, Zsolt; Smith, R Theodore; Curcio, Christine A; Ach, Thomas

    2016-01-01

    The human retinal pigment epithelium (RPE) is reportedly 3% bi-nucleated. The importance to human vision of multi-nucleated (MN)-RPE cells could be clarified with more data about their distribution in central retina. Nineteen human RPE-flatmounts (9 ≤ 51 years, 10 > 80 years) were imaged at 12 locations: 3 eccentricities (fovea, perifovea, near periphery) in 4 quadrants (superior, inferior, temporal, nasal). Image stacks of lipofuscin-attributable autofluorescence and phalloidin labeled F-actin cytoskeleton were obtained using a confocal fluorescence microscope. Nuclei were devoid of autofluorescence and were marked using morphometric software. Cell areas were approximated by Voronoi regions. Mean number of nuclei per cell among eccentricity/quadrant groups and by age were compared using Poisson and binominal regression models. A total of 11,403 RPE cells at 200 locations were analyzed: 94.66% mono-, 5.31% bi-, 0.02% tri-nucleate, and 0.01% with 5 nuclei. Age had no effect on number of nuclei. There were significant regional differences: highest frequencies of MN-cells were found at the perifovea (9.9%) and near periphery (6.8%). The fovea lacked MN-cells almost entirely. The nasal quadrant had significantly more MN-cells compared to other quadrants, at all eccentricities. This study demonstrates MN-RPE cells in human macula. MN-cells may arise due to endoreplication, cell fusion, or incomplete cell division. The topography of MN-RPE cells follows the topography of photoreceptors; with near-absence at the fovea (cones only) and high frequency at perifovea (highest rod density). This distribution might reflect specific requirements of retinal metabolism or other mechanisms addressable in further studies.

  19. Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality.

    Science.gov (United States)

    Liu, Shanqiu; Eijkelenkamp, Rik; Duvigneau, Joost; Vancso, G Julius

    2017-11-01

    Core-shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO 2 -blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell material as it possesses a low surface energy and high CO 2 -philicity. The successful synthesis of core-shell nanoparticles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The cell size and cell density of the PMMA micro- and nanocellular materials were determined by scanning electron microscopy. The cell nucleation efficiency using core-shell nanoparticles was significantly enhanced when compared to that of unmodified silica. The highest nucleation efficiency observed had a value of ∼0.5 for nanoparticles with a core diameter of 80 nm. The particle size dependence of cell nucleation efficiency is discussed taking into account line tension effects. Complete engulfment by the polymer matrix of particles with a core diameter below 40 nm at the cell wall interface was observed corresponding to line tension values of approximately 0.42 nN. This line tension significantly increases the energy barrier of heterogeneous nucleation and thus reduces the nucleation efficiency. The increase of the CO 2 saturation pressure to 300 bar prior to batch foaming resulted in an increased line tension length. We observed a decrease of the heterogeneous nucleation efficiency for foaming after saturation with CO 2 at 300 bar, which we attribute to homogenous nucleation becoming more favorable at the expense of heterogeneous nucleation in this case. Overall, it is shown that the contribution of line tension to the free energy barrier of heterogeneous foam cell nucleation must be considered to understand foaming of viscoelastic materials. This finding emphasizes the need for new strategies including the use of

  20. Nonreassuring fetal heart rate patterns and nucleated red blood cells in term neonates.

    Science.gov (United States)

    Kovalak, E Ebru; Dede, F Suat; Gelisen, Orhan; Dede, Hulya; Haberal, Ali

    2011-05-01

    The aim of this study was to evaluate the association between nonreassuring fetal heart rate patterns during labor and umbilical cord nucleated red blood cell counts. Nucleated red blood cell data was collected prospectively from 41 singleton term neonates presented with nonreassuring fetal heart rate patterns and/or meconium stained amniotic fluid during labor (study group) and from 45 term neonates without any evidence of nonreassuring fetal status (controls). Umbilical artery pH, blood gases and base excess were also determined to investigate the correlation between independent variables. The median nucleated red blood cells per 100 white blood cells were 13 (range 0-37) in the study group and 8 (range 0-21) in the control group. Stepwise regression analysis have identified meconium stained amniotic fluid (R(2) = 0.15, p patterns. Nucleated red blood cells in the cord blood of newborns were found to be elevated in patients with nonreassuring FHR patterns during labor. However, the wide range and the poor correlation of NRBC count with umbilical artery pH and blood gas values limit its clinical utility as a marker for fetal hypoxia.

  1. Changes in total and differential white cell counts, total lymphocyte ...

    African Journals Online (AJOL)

    Background: Published reports on the possible changes in the various immune cell populations, especially the total lymphocyte and CD4 cell counts, during the menstrual cycle in Nigerian female subjects are relatively scarce. Aim: To determine possible changes in the total and differential white blood cell [WBC] counts, ...

  2. TONNEAU2/FASS Regulates the Geometry of Microtubule Nucleation and Cortical Array Organization in Interphase Arabidopsis Cells[C][W

    Science.gov (United States)

    Kirik, Angela; Ehrhardt, David W.; Kirik, Viktor

    2012-01-01

    Organization of microtubules into ordered arrays involves spatial and temporal regulation of microtubule nucleation. Here, we show that acentrosomal microtubule nucleation in plant cells involves a previously unknown regulatory step that determines the geometry of microtubule nucleation. Dynamic imaging of interphase cortical microtubules revealed that the ratio of branching to in-bundle microtubule nucleation on cortical microtubules is regulated by the Arabidopsis thaliana B′′ subunit of protein phosphatase 2A, which is encoded by the TONNEAU2/FASS (TON2) gene. The probability of nucleation from γ-tubulin complexes localized at the cell cortex was not affected by a loss of TON2 function, suggesting a specific role of TON2 in regulating the nucleation geometry. Both loss of TON2 function and ectopic targeting of TON2 to the plasma membrane resulted in defects in cell shape, suggesting the importance of TON2-mediated regulation of the microtubule cytoskeleton in cell morphogenesis. Loss of TON2 function also resulted in an inability for cortical arrays to reorient in response to light stimulus, suggesting an essential role for TON2 and microtubule branching nucleation in reorganization of microtubule arrays. Our data establish TON2 as a regulator of interphase microtubule nucleation and provide experimental evidence for a novel regulatory step in the process of microtubule-dependent nucleation. PMID:22395485

  3. Numerical model for the deformation of nucleated cells by optical stretchers

    KAUST Repository

    Sraj, Ihab

    2015-07-01

    In this paper, we seek to numerically study the deformation of nucleated cells by single diode-laser bar optical stretchers. We employ a recently developed computational model, the dynamic ray-tracing method, to determine the force distribution induced by optical stretchers on a cell encapsulating a nucleus of different optical properties. These optical forces are shape dependent and can deform real non-rigid objects; thus resulting in dynamically changing distributions with cell and nucleus deformation. A Chinese hamster ovary (CHO) cell is a common biological cell that is of interest to the biomedical community because of its use in recombinant protein therapeutics and is an example of a nucleated cell. To this end, we model CHO cells as two concentric three-dimensional elastic capsules immersed in a fluid where the hydrodynamic forces are calculated using the immersed boundary method. We vary the inner capsule size to simulate different nucleus sizes. Our results show that the presence of a nucleus has a major effect on the force distribution on the cell surface and consequently on its net deformation. Scattering and gradient forces are reported for different nucleus sizes and the effect of nucleus size on the cell deformation is discussed quantitatively. © 2015 IOP Publishing Ltd.

  4. ASSOCIATION OF BIRTH ASPHYXIA WITH CORD BLOOD NUCLEATED RED BLOOD CELL

    Directory of Open Access Journals (Sweden)

    Poornima Shankar

    2018-02-01

    Full Text Available BACKGROUND Asphyxia can lead to severe hypoxic ischaemic organ damage in new-borns which may cause postnatal manifestation of hypoxicischaemic encephalopathy. Studies have found that the Apgar score failed to predict specific neurologic outcomes of the infants. Increased cord blood nucleated red blood cell in term neonates is an indicator of chronic intrauterine hypoxia. We set out to assess the role of nucleated RBC as a non-invasive, easy, cheap and at the same time early biochemical means of asphyxia diagnosis in our clinical setting. MATERIALS AND METHODS All inborn babies with Apgar scores <7 at 1 and 5 minutes of life were reviewed. Relevant information from mother case sheet were obtained. Cord blood samples was drawn and sent for blood gas analysis and number of NRBCs/100 white blood cells (WBC was determined using Leishman stain. RESULTS Our study proves the relevance of increase nucleated RBC in terms of early detection of birth asphyxia. Most common cause of birth asphyxia found was meconium aspiration. No co-relation was found with chorioamnionitis or maternal obstetrical history. CONCLUSION Many specific biomarkers are being investigated now a day for early detection of birth asphyxia. Umbilical cord pH is costly and may be underestimated in birth asphyxia. In our study, the elevated cord blood nRBC count was shown to be a good predictor of perinatal asphyxia. Since, it is cost-effective and does not require any special expertise or any high-tech facilities, it may be a useful, reliable, inexpensive and easily available marker to evaluate perinatal asphyxia. Hence, increase nucleated RBC has an important role in diagnosing and predicting the outcome of perinatal asphyxia.

  5. Umbilical nucleated red blood cell as a sign of fetal distress

    Directory of Open Access Journals (Sweden)

    Torkestani F

    2008-06-01

    Full Text Available Background: The presence of increased numbers of nucleated red blood cell (NRBC in the umbilical cord blood has been associated with states of relative hypoxia. Nucleated red blood cell counts are a potentially useful tool in estimating the degree and timing of intrauterine hypoxia. This may have important implication in determining causality in case of compromised infant. Cord blood NRBC counts may be obtained noninvasively from an otherwise discarded specimen and analyzed by personnel on equipment readily available in most hospital laboratories. Since the aim of monitoring of fetal heart is early diagnosis of hypoxia, we studied the relationship between abnormal fetal heart rate with the number of nucleated red blood cells (NRBC in the umbilical cord blood.Methods: We performed this research at Hazrat Zeynab Hospital on 130 full-term newborns (65 cases of fetal distress and 65 normal cases between July 2005 and July 2006. The NRBC counts of newborns with abnormal fetal heart rate were compared with those of normal newborns and correlations with other parameters including Apgar score, hemoglobin level, condition of newborns in the first 24 hours of the birth and birth weight.Results: The mean NRBC count in the fetal distress group was 9.45 ± 8.75 and that of the normal group was 9.17 ± 8.76 per 100 white cells (p=0.89. The mean duration between diagnosis of fetal distress to birth was equal to 1.2± 0.77 hours. Furthermore, there was no meaningful correlation between number of NRBC and Apgar score, hemoglobin, birth weight and condition of newborns in the first 24 hours.Conclusion: If the fetus is born a short time after the diagnosis of distress with no risk factors for hypoxia, the NRBC count for cord blood is not elevated.

  6. The DNA damage of high doses of X-ray on human peripheral blood nucleated cell's and sperm

    International Nuclear Information System (INIS)

    Wang Hui; Zoulian; Jiang Qisheng; Li Fengsheng; He Rui; Song Xiujun

    2011-01-01

    Objective: To detect the DNA damage of high doses of X-ray on human peripheral blood nucleated cell's and sperm by single cell gel electrophoresis (SCGE). Evaluation the level of DNA damage of human peripheral blood nucleated cell's and sperm after high doses of X-ray. Methods: Using human peripheral blood with normal blood routine and normal sperm,give the dose of 0 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, 10 Gy X-ray radiation with energy of 6MU. Detect the percentage of comet-like tail, tail length and content of DNA in tail of whole blood cell's DNA and sperm's DNA by SCGE technique in 1 hour. Results: The peripheral blood nucleated cell's and sperm's comet rate were 1.00±0.10%, 2.1±1.5%, respectively, have an evidently variance in 0 Gy group (υ=18, t=2.31>1.734, P 1.734, P 1.734, P<0.05). The peripheral blood nucleated cell's and sperm's comet rate were all 100%, 100%, have no-statistical significance in 8 Gy, 10 Gy group. Conclusion: The evidence is powerful enough. That the sperm's SCGE is more sensitive than peripheral blood nucleated cell's SCGE in reflect the X-ray damage in a certain extent (2-6 Gy). (authors)

  7. Neonatal nucleated red blood cells in infants of overweight and obese mothers.

    Science.gov (United States)

    Sheffer-Mimouni, Galit; Mimouni, Francis B; Dollberg, Shaul; Mandel, Dror; Deutsch, Varda; Littner, Yoav

    2007-06-01

    The perinatal outcome of the infant of obese mother is adversely affected and in theory, may involve fetal hypoxia. We hypothesized that an index of fetal hypoxia, the neonatal nucleated red blood cell (NRBC) count, is elevated in infants of overweight and obese mothers. Absolute NRBC counts taken during the first 12 hours of life in 41 infants of overweight and obese mothers were compared to 28 controls. Maternal body mass index and infant birthweight were significantly higher in the overweight and obese group (P cell and lymphocyte counts did not differ between groups. The absolute NRBC count was higher (P = 0.01), and the platelet count lower (P = 0.05) in infants of overweight and obese mothers than in controls. In stepwise regression analysis, the absolute NRBC count in infants of overweight and obese mothers remained significantly higher even after taking into account birthweight or gestational age and Apgar scores (P mothers have increased nucleated red blood cells at birth compared with controls. We speculate that even apparently healthy fetuses of overweight and obese mothers are exposed to a subtle hypoxemic environment.

  8. Homogenous Nucleation Rates of n-Propanol Measured in the Laminar Flow Diffusion Chamber at Different Total Pressures.

    Czech Academy of Sciences Publication Activity Database

    Neitola, K.; Hyvärinen, A.-P.; Lihavainen, H.; Wölk, J.; Strey, R.; Brus, David

    2014-01-01

    Roč. 140, č. 17 (2014), č. článku 174301. ISSN 0021-9606 Grant - others:AFCE(FI) 1118615 Institutional support: RVO:67985858 Keywords : carbon-chain length * equilibrium vapor * homogenous nucleation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.952, year: 2014

  9. TSPAN7, effector of actin nucleation required for dendritic cell-mediated transfer of HIV-1 to T cells.

    Science.gov (United States)

    Ménager, Mickaël M

    2017-06-15

    Dendritic cells (DCs) have essential roles in early detection of pathogens and activation of both innate and adaptive immune responses. Whereas human DCs are resistant to productive HIV-1 replication, they have a unique ability to take up virus and transmit it efficiently to T lymphocytes. By doing that, HIV-1 may evade, at least in part, the first line of defense of the immune system, exploiting DCs instead to facilitate rapid infection of a large pool of immune cells. While performing an shRNA screen in human primary monocyte-derived DCs, to gain insights into this cell biological process, we discovered the role played by tetraspanin-7 (TSPAN7). This member of the tetraspanin family appears to be a positive regulator of actin nucleation and stabilization, through the ARP2/3 complex. By doing so, TSPAN7 limits HIV-1 endocytosis and maintains viral particles on actin-rich dendrites for an efficient transfer toward T lymphocytes. While studying the function of TSPAN7 in the control of actin nucleation, we also discovered the existence in DCs of two opposing forces at the plasma membrane: actin nucleation, a protrusive force which seems to counterbalance actomyosin contraction. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  10. Nucleated red blood cells count in pregnancies with idiopathic intra-uterine growth restriction.

    Directory of Open Access Journals (Sweden)

    Fatemeh Davari-Tanha

    2014-06-01

    Full Text Available Elevated nucleated red blood cell (NRBC count is introduced as a potential marker of intra-uterine growth restriction (IUGR. To investigate the probable association regardless of any known underlying disease, we aimed to study disturbances in NRBC count in infants experiencing idiopathic IUGR.Twenty three infants regarded IUGR without any known cause were chosen to be compared to 48 normal neonates. Blood samples were collected instantly after birth and the same measurements were done in both groups.NRBC count/100 white blood cells was significantly higher in the IUGR group (P value < 0.001. pH measurements did not reveal any significant difference.Increased NRBC count in cases of idiopathic IUGR in absence of chronic hypoxia could strengthen its predictive value suggested in previous studies. It could help early IUGR detection and beneficial intervention.

  11. Optimising methods of red cell sedimentation from cord blood to maximise nucleated cell recovery prior to cryopreservation.

    Science.gov (United States)

    Madkaikar, M; Gupta, M; Ghosh, K; Swaminathan, S; Sonawane, L; Mohanty, D

    2007-01-01

    Human cord blood is now an established source of stem cells for haematopoietic reconstitution. Red blood cell (RBC) depletion is required to reduce the cord blood unit volume for commercial banking. Red cell sedimentation using hydroxy ethyl starch (HES) is a standard procedure in most cord blood banks. However, while standardising the procedure for cord blood banking, a significant loss of nucleated cells (NC) may be encountered during standard HES sedimentation protocols. This study compares four procedures for cord blood processing to obtain optimal yield of nucleated cells. Gelatin, dextran, 6% HES and 6% HES with an equal volume of phosphate-buffered saline (PBS) were compared for RBC depletion and NC recovery. Dilution of the cord blood unit with an equal volume of PBS prior to sedimentation with HES resulted in maximum NC recovery (99% [99.5 +/- 1.3%]). Although standard procedures using 6% HES are well established in Western countries, they may not be applicable in India, as a variety of factors that can affect RBC sedimentation (e.g., iron deficiency, hypoalbuminaemia, thalassaemia trait, etc.) may reduce RBC sedimentation and thus reduce NC recovery. While diluting cord blood with an equal volume of PBS is a simple method to improve the NC recovery, it does involve an additional processing step.

  12. A gravimetric simplified method for nucleated marrow cell counting using an injection needle.

    Science.gov (United States)

    Saitoh, Toshiki; Fang, Liu; Matsumoto, Kiyoshi

    2005-08-01

    A simplified gravimetric marrow cell counting method for rats is proposed for a regular screening method. After fresh bone marrow was aspirated by an injection needle, the marrow cells were suspended in carbonate buffered saline. The nucleated marrow cell count (NMC) was measured by an automated multi-blood cell analyzer. When this gravimetric method was applied to rats, the NMC of the left and right femurs had essentially identical values due to careful handling. The NMC at 4 to 10 weeks of age in male and female Crj:CD(SD)IGS rats was 2.72 to 1.96 and 2.75 to 1.98 (x10(6) counts/mg), respectively. More useful information for evaluation could be obtained by using this gravimetric method in addition to myelogram examination. However, some difficulties with this method include low NMC due to blood contamination and variation of NMC due to handling. Therefore, the utility of this gravimetric method for screening will be clarified by the accumulation of the data on myelotoxicity studies with this method.

  13. Analysis of Giant-nucleated Cell Formation Following X-ray and Proton Irradiations

    Science.gov (United States)

    Almahwasi, Ashraf Abdu

    Radiation-induced genetic instability has been observed in survivors of irradiated cancerous and normal cells in vitro and in vivo and has been determined in different forms, such as delayed cell death, chromosomal aberration or mutation. A well defined and characterized normal human-diploid AG1522 fibroblast cell line was used to study giant-nucleated cell (GCs) formation as the ultimate endpoint of this research. The average nuclear cross-sectional areas of the AG1522 cells were measured in mum2. The doubling time required by the AG1522 cells to divide was measured. The potential toxicity of the Hoechst dye at a working concentration on the live AG1522 cells was assessed. The yield of giant cells was determined at 7, 14 and 21 days after exposure to equivalent clinical doses of 0.2, 1 or 2 Gy of X-ray or proton irradiation. Significant differences were found to exist between X-ray or proton irradiation when compared with sham-irradiated control populations. The frequency of GCs induced by X-rays was also compared to those formed in proton irradiated cultures. The results confirm that 1 Gy X-rays are shown to induce higher rates of mitotically arrested GCs, increasing continually over time up to 21 days post-irradiation. The yield of GCs was significantly greater (10%) compared to those formed in proton populations (2%) 21 days postirradiation. The GCs can undergo a prolonged mitotic arrest that significantly increases the length of cell cycle. The arrest of GCs at the mitotic phase for longer periods of time might be indicative of a strategy for cell survival, as it increases the time available for DNA repair and enables an alternative route to division for the cells. However, the reduction in their formation 21 days after both types of radiation might favour GCs formation, ultimately contributing to carcinogenesis or cancer therapy resistance. The X-ray experiments revealed a dose-dependent increase in the GCs up to 14 days after irradiation. Although the proton

  14. Analysis of mtDNT 4977bp deletion induced by ionizing radiation in human peripheral blood nucleated cells using real-time PCR

    International Nuclear Information System (INIS)

    Fan Tianli; Wang Ping; Han Lin; Liu Yulong; Liu Yumin

    2010-01-01

    To detect mitochondrial DNA(mtDNA) 4977bp deletion(triangle open mtDNA 4977 ) in human peripheral blood nucleated cells exposed to ionizing radiation in vitro by using real-time PCR, and explore possibility of the index as biodosimetry for estimating biological dose in radiation accident,six healthy individuals' peripheral blood was collected,and the blood samples were irradiated with 0,1,2,3,4 and 5 Gy 60 Co gamma-ray. The triangle open mtDNA 4977 and total mtDNA copy number(mtDNA total ) in the mtDNA samples were detected, and then the deletion rates were calculated. The results showed that the mtDNA total and triangle open mtDNA 4977 copy number, and the deletion rates of mtDNA 4977bp in the mtDNA samples from 6 healthy individuals' blood exposed to 1-5 Gy radiation were higher than that with the samples exposed to 0 Gy radiation(p 0.05). The results indicated that ionizing radiation can induce accumulation of the triangle open mtDNA 4977 and increase of mtDNA total copy number in human peripheral blood nucleated cells,but both the mtDNA 4977bp deletion and exposure dose(0-5 Gy) were not obviously correlated. (authors)

  15. Total hip arthroplasty for giant cell tumour.

    Directory of Open Access Journals (Sweden)

    Kulkarni S

    1996-07-01

    Full Text Available A 32 month follow up of an uncommon case of a Giant Cell Tumour affecting the proximal end of femur is presented. Following a wide excision, the hip was reconstructed using Charnley type of low friction total hip arthroplasty. At a 32 month review, there was no recurrence and the function was good.

  16. Transcriptomic profiling of peripheral blood nucleated cells in dogs with and without clinical signs of chronic mitral valve disease

    Directory of Open Access Journals (Sweden)

    Garncarz Magdalena

    2014-03-01

    Full Text Available The aim of the study was to demonstrate differences in the gene expression of signalling pathways between healthy dogs and dogs with chronic mitral valve disease in different heart failure groups. Blood samples were collected from 49 dogs of various breeds between 1.4 and 15.2 years of age. Isolated RNA samples were analysed for quality and integrity and the gene expression profile was determined. The study demonstrated that nucleated cells from peripheral blood can be used to assess the status of heart failure in dogs. Furthermore, significant differences in the expression of the genes were noticed between healthy dogs and dogs with clinical signs of chronic mitral valve disease. This is a preliminary non-invasive study showing the feasibility of genetic testing from peripheral blood nucleated cells, which at the same time has made it possible to set the future directions of genetic studies in clinical cases of canine chronic mitral valve disease.

  17. A note on the nucleation with multiple steps: Parallel and series nucleation

    OpenAIRE

    Iwamatsu, Masao

    2012-01-01

    Parallel and series nucleation are the basic elements of the complex nucleation process when two saddle points exist on the free-energy landscape. It is pointed out that the nucleation rates follow formulas similar to those of parallel and series connection of resistors or conductors in an electric circuit. Necessary formulas to calculate individual nucleation rates at the saddle points and the total nucleation rate are summarized and the extension to the more complex nucleation process is su...

  18. Nucleated red blood cells and early EEG: predicting Sarnat stage and two year outcome.

    LENUS (Irish Health Repository)

    Walsh, B H

    2012-01-31

    AIMS: Hypoxic Ischaemic Encephalopathy (HIE) causes characteristic changes of the electroencephalogram (EEG), and a raised Nucleated Red Blood Cell (NRBC) count compared to controls. We wished to examine whether combining these markers could improve their ability to predict HIE severity in the first 24h. METHODS: Term infants with HIE were recruited. NRBC count and continuous multi-channel EEG were recorded within the first 24h. Neurological assessment was carried out at 24 months. A control population with NRBC counts in the first 24h was recruited. RESULTS: 44 infants with HIE and 43 control infants were recruited. Of the HIE population 39 completed a 2 year follow-up. The median NRBC count differed significantly between the controls and those with HIE (3\\/100 WBC [range of 0-11] vs 12.3\\/100 WBC [0-240]) (p<0.001). Within the HIE population the median NRBC count was significantly greater in infants with moderate\\/severe HIE than mild (16\\/100 WBC [range of 0-240] vs 8\\/100 WBC [1-23]) (p=0.016), and among infants with abnormal outcome compared to normal (21.3\\/100 WBC [1-239.8] vs 8.3\\/100 WBC [0-50])(p=0.03). The predictive ability of EEG changed with time post-delivery, therefore results are given at both 12 and 24h of age. At both time points the combined marker had a stronger correlation than EEG alone; with HIE severity (12h: r=0.661 vs r=0.622), (24h: r=0.645 vs r=0.598), and with outcome at 2 years (12h: r=0.756 vs r=0.652), (24h: r=0.802 vs r=0.746). CONCLUSION: Combining early EEG and NRBC count to predict HIE severity and neurological outcome, improved the predictive ability of either in isolation.

  19. Reference ranges for blood concentrations of nucleated red blood cells in neonates.

    Science.gov (United States)

    Christensen, Robert D; Henry, Erick; Andres, Robert L; Bennett, Sterling T

    2011-01-01

    Previous studies reported a relationship between high nucleated red blood cells (NRBC) in neonates and the development of intraventricular hemorrhage (IVH) and/or retinopathy of prematurity (ROP). We sought to (1) establish reference ranges for NRBC in neonates based on a large data set, (2) compare NRBC from automated versus manual counts, (3) determine the effect of an elevated NRBC, on the day of birth, on the odds of developing grade ≥3 IVH or ROP. We analyzed all NRBC obtained during 8.5 years in a multihospital system, displaying the 5th and 95th percentile limits according to gestational age and postnatal age. NRBC counts were retrieved from 61,932 neonates, 26,536 of which were excluded from the data set. Comparing 9,000 samples run simultaneously on manual versus automated methods, the manual counts yielded slightly higher counts, but the difference is likely insignificant clinically. Altitude of the birth hospital did not correlate with NRBC, and no correlations were observed with cord pH or 1- or 5-min Apgar. An NRBC count >95th percentile limit was associated with higher odds of developing a grade ≥3 IVH (OR 4.28; 95% CI 3.17-5.77) and grade ≥3 ROP (OR 4.18; 95% CI 2.74-6.38). The figures of this report display reference ranges for NRBC according to gestational age and postnatal age. An NRBC count above the 95% limit at birth is associated with a higher risk of subsequently developing severe IVH and severe ROP. We speculate that this association is because an elevated NRBC count is a marker for prenatal hypoxia. Copyright © 2010 S. Karger AG, Basel.

  20. In Silico Functional Networks Identified in Fish Nucleated Red Blood Cells by Means of Transcriptomic and Proteomic Profiling.

    Science.gov (United States)

    Puente-Marin, Sara; Nombela, Iván; Ciordia, Sergio; Mena, María Carmen; Chico, Verónica; Coll, Julio; Ortega-Villaizan, María Del Mar

    2018-04-09

    Nucleated red blood cells (RBCs) of fish have, in the last decade, been implicated in several immune-related functions, such as antiviral response, phagocytosis or cytokine-mediated signaling. RNA-sequencing (RNA-seq) and label-free shotgun proteomic analyses were carried out for in silico functional pathway profiling of rainbow trout RBCs. For RNA-seq, a de novo assembly was conducted, in order to create a transcriptome database for RBCs. For proteome profiling, we developed a proteomic method that combined: (a) fractionation into cytosolic and membrane fractions, (b) hemoglobin removal of the cytosolic fraction, (c) protein digestion, and (d) a novel step with pH reversed-phase peptide fractionation and final Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC ESI-MS/MS) analysis of each fraction. Combined transcriptome- and proteome- sequencing data identified, in silico, novel and striking immune functional networks for rainbow trout nucleated RBCs, which are mainly linked to innate and adaptive immunity. Functional pathways related to regulation of hematopoietic cell differentiation, antigen presentation via major histocompatibility complex class II (MHCII), leukocyte differentiation and regulation of leukocyte activation were identified. These preliminary findings further implicate nucleated RBCs in immune function, such as antigen presentation and leukocyte activation.

  1. In Silico Functional Networks Identified in Fish Nucleated Red Blood Cells by Means of Transcriptomic and Proteomic Profiling

    Directory of Open Access Journals (Sweden)

    Sara Puente-Marin

    2018-04-01

    Full Text Available Nucleated red blood cells (RBCs of fish have, in the last decade, been implicated in several immune-related functions, such as antiviral response, phagocytosis or cytokine-mediated signaling. RNA-sequencing (RNA-seq and label-free shotgun proteomic analyses were carried out for in silico functional pathway profiling of rainbow trout RBCs. For RNA-seq, a de novo assembly was conducted, in order to create a transcriptome database for RBCs. For proteome profiling, we developed a proteomic method that combined: (a fractionation into cytosolic and membrane fractions, (b hemoglobin removal of the cytosolic fraction, (c protein digestion, and (d a novel step with pH reversed-phase peptide fractionation and final Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC ESI-MS/MS analysis of each fraction. Combined transcriptome- and proteome- sequencing data identified, in silico, novel and striking immune functional networks for rainbow trout nucleated RBCs, which are mainly linked to innate and adaptive immunity. Functional pathways related to regulation of hematopoietic cell differentiation, antigen presentation via major histocompatibility complex class II (MHCII, leukocyte differentiation and regulation of leukocyte activation were identified. These preliminary findings further implicate nucleated RBCs in immune function, such as antigen presentation and leukocyte activation.

  2. Giant cells around bone biomaterials: Osteoclasts or multi-nucleated giant cells?

    Science.gov (United States)

    Miron, Richard J; Zohdi, Hamoon; Fujioka-Kobayashi, Masako; Bosshardt, Dieter D

    2016-12-01

    Recently accumulating evidence has put into question the role of large multinucleated giant cells (MNGCs) around bone biomaterials. While cells derived from the monocyte/macrophage lineage are one of the first cell types in contact with implanted biomaterials, it was originally thought that specifically in bone tissues, all giant cells were bone-resorbing osteoclasts whereas foreign body giant cells (FBGCs) were found associated with a connective tissue foreign body reaction resulting in fibrous encapsulation and/or material rejection. Despite the great majority of bone grafting materials routinely found with large osteoclasts, a special subclass of bone biomaterials has more recently been found surrounded by large giant cells virtually incapable of resorbing bone grafts even years after their implantation. While original hypotheses believed that a 'foreign body reaction' may be taking place, histological data retrieved from human samples years after their implantation have put these original hypotheses into question by demonstrating better and more stable long-term bone volume around certain bone grafts. Exactly how or why this 'special' subclass of giant cells is capable of maintaining long-term bone volume, or methods to scientifically distinguish them from osteoclasts remains extremely poorly studied. The aim of this review article was to gather the current available literature on giant cell markers and differences in expression patterns between osteoclasts and MNGCs utilizing 19 specific markers including an array of CD-cell surface markers. Furthermore, the concept of now distinguishing between pro-inflammatory M1-MNGCs (previously referred to as FBGCs) as well as wound-healing M2-MNGCs is introduced and discussed. This review article presents 19 specific cell-surface markers to distinguish between osteoclasts and MNGCs including an array of CD-cell surface markers. Furthermore, the concept of now distinguishing between pro-inflammatory M1-MNGCs (often

  3. Nucleation from a cluster of inclusions, leading to void coalescense

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2017-01-01

    A cell model analysis is used to study the nucleation and subsequent growth of voids from a non-uniform distribution of inclusions in a ductile material. Nucleation is modeled as either stress controlled or strain controlled. The special clusters considered consist of a number of uniformly spaced...... inclusions located along a plane perpendicular to the maximum principal tensile stress. A plane strain approximation is used, where the inclusions are parallel cylinders perpendicular to the plane. Clusters with different numbers of inclusions are compared with the nucleation and growth from a single...... inclusion, such that the total initial volume of the inclusions is the same for the clusters and the single inclusion. After nucleation, local void coalescence inside the clusters is accounted for, since this makes it possible to compare the rate of growth of the single larger void that results from...

  4. A note on the nucleation with multiple steps: parallel and series nucleation.

    Science.gov (United States)

    Iwamatsu, Masao

    2012-01-28

    Parallel and series nucleation are the basic elements of the complex nucleation process when two saddle points exist on the free-energy landscape. It is pointed out that the nucleation rates follow formulas similar to those of parallel and series connection of resistors or conductors in an electric circuit. Necessary formulas to calculate individual nucleation rates at the saddle points and the total nucleation rate are summarized, and the extension to the more complex nucleation process is suggested. © 2012 American Institute of Physics

  5. CORD BLOOD NUCLEATED RED BLOOD CELL COUNT: A SIMPLE BEDSIDE TEST OF PERINATAL ASPHYXIA AND ITS CORRELATION WITH IMMEDIATE OUTCOME

    Directory of Open Access Journals (Sweden)

    Ramesh Chand

    2016-07-01

    Full Text Available BACKGROUND Asphyxia is a leading cause of foetal neonatal mortality and morbidity. Nucleated red blood cell count (NRBC produced as compensatory response to asphyxia in foetus and NRBC level can be correlated to asphyxia. Because the present indices are unhelpful in the diagnosis and prediction of the severity of asphyxia, we wished to investigate the relationship between the nucleated RBC count and the severity & immediate outcome of perinatal asphyxia. METHOD This prospective comparative study was conducted in maternity ward of Obstetrics & Gynaecology Department and Paediatric Department of GSVM Medical College, Kanpur (Central UP, from January 2014 to September 2014. Newborns of term gestation were selected after satisfying inclusion criteria and were divided in 2 groups. The control group consisted 60 normal newborns and case group had 60 asphyxiated newborns. The cord blood was collected soon after birth, investigated for pH and making smears that were stained with Leishman’s stain. NRBCs were counted against 100 WBCs. The statistical analysis was done using IMSTAT. RESULTS The mean NRBC count in the study group was 22.63±6.95 as compared to 4.75±2.04 in the control group (p=<0.0001. The NRBC count was significantly higher in low pH, neonates with low Apgar scores of < 3 at 1 minutes, newborns with HIE stage III & in neonates who were neurological abnormal at discharge (P=0.0001. CONCLUSIONS A simple, easy to do, cost effective bedside test, such as NRBC count at time of delivery is a good marker of perinatal asphyxia & its forthcoming immediate neurological outcome.

  6. Climate Impacts of Ice Nucleation

    Science.gov (United States)

    Gettelman, Andrew; Liu, Xiaohong; Barahona, Donifan; Lohmann, Ulrike; Chen, Celia

    2012-01-01

    Several different ice nucleation parameterizations in two different General Circulation Models (GCMs) are used to understand the effects of ice nucleation on the mean climate state, and the Aerosol Indirect Effects (AIE) of cirrus clouds on climate. Simulations have a range of ice microphysical states that are consistent with the spread of observations, but many simulations have higher present-day ice crystal number concentrations than in-situ observations. These different states result from different parameterizations of ice cloud nucleation processes, and feature different balances of homogeneous and heterogeneous nucleation. Black carbon aerosols have a small (0.06 Wm(exp-2) and not statistically significant AIE when included as ice nuclei, for nucleation efficiencies within the range of laboratory measurements. Indirect effects of anthropogenic aerosols on cirrus clouds occur as a consequence of increasing anthropogenic sulfur emissions with different mechanisms important in different models. In one model this is due to increases in homogeneous nucleation fraction, and in the other due to increases in heterogeneous nucleation with coated dust. The magnitude of the effect is the same however. The resulting ice AIE does not seem strongly dependent on the balance between homogeneous and heterogeneous ice nucleation. Regional effects can reach several Wm2. Indirect effects are slightly larger for those states with less homogeneous nucleation and lower ice number concentration in the base state. The total ice AIE is estimated at 0.27 +/- 0.10 Wm(exp-2) (1 sigma uncertainty). This represents a 20% offset of the simulated total shortwave AIE for ice and liquid clouds of 1.6 Wm(sup-2).

  7. Nesprin-1α-Dependent Microtubule Nucleation from the Nuclear Envelope via Akap450 Is Necessary for Nuclear Positioning in Muscle Cells.

    Science.gov (United States)

    Gimpel, Petra; Lee, Yin Loon; Sobota, Radoslaw M; Calvi, Alessandra; Koullourou, Victoria; Patel, Rutti; Mamchaoui, Kamel; Nédélec, François; Shackleton, Sue; Schmoranzer, Jan; Burke, Brian; Cadot, Bruno; Gomes, Edgar R

    2017-10-09

    The nucleus is the main microtubule-organizing center (MTOC) in muscle cells due to the accumulation of centrosomal proteins and microtubule (MT) nucleation activity at the nuclear envelope (NE) [1-4]. The relocalization of centrosomal proteins, including Pericentrin, Pcm1, and γ-tubulin, depends on Nesprin-1, an outer nuclear membrane (ONM) protein that connects the nucleus to the cytoskeleton via its N-terminal region [5-7]. Nesprins are also involved in the recruitment of kinesin to the NE and play a role in nuclear positioning in skeletal muscle cells [8-12]. However, a function for MT nucleation from the NE in nuclear positioning has not been established. Using the proximity-dependent biotin identification (BioID) method [13, 14], we found several centrosomal proteins, including Akap450, Pcm1, and Pericentrin, whose association with Nesprin-1α is increased in differentiated myotubes. We show that Nesprin-1α recruits Akap450 to the NE independently of kinesin and that Akap450, but not other centrosomal proteins, is required for MT nucleation from the NE. Furthermore, we demonstrate that this mechanism is disrupted in congenital muscular dystrophy patient myotubes carrying a nonsense mutation within the SYNE1 gene (23560 G>T) encoding Nesprin-1 [15, 16]. Finally, using computer simulation and cell culture systems, we provide evidence for a role of MT nucleation from the NE on nuclear spreading in myotubes. Our data thus reveal a novel function for Nesprin-1α/Nesprin-1 in nuclear positioning through recruitment of Akap450-mediated MT nucleation activity to the NE. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  8. Incorporating C60 as Nucleation Sites Optimizing PbI2 Films To Achieve Perovskite Solar Cells Showing Excellent Efficiency and Stability via Vapor-Assisted Deposition Method.

    Science.gov (United States)

    Chen, Hai-Bin; Ding, Xi-Hong; Pan, Xu; Hayat, Tasawar; Alsaedi, Ahmed; Ding, Yong; Dai, Song-Yuan

    2018-01-24

    To achieve high-quality perovskite solar cells (PSCs), the morphology and carrier transportation of perovskite films need to be optimized. Herein, C 60 is employed as nucleation sites in PbI 2 precursor solution to optimize the morphology of perovskite films via vapor-assisted deposition process. Accompanying the homogeneous nucleation of PbI 2 , the incorporation of C 60 as heterogeneous nucleation sites can lower the nucleation free energy of PbI 2 , which facilitates the diffusion and reaction between PbI 2 and organic source. Meanwhile, C 60 could enhance carrier transportation and reduce charge recombination in the perovskite layer due to its high electron mobility and conductivity. In addition, the grain sizes of perovskite get larger with C 60 optimizing, which can reduce the grain boundaries and voids in perovskite and prevent the corrosion because of moisture. As a result, we obtain PSCs with a power conversion efficiency (PCE) of 18.33% and excellent stability. The PCEs of unsealed devices drop less than 10% in a dehumidification cabinet after 100 days and remain at 75% of the initial PCE during exposure to ambient air (humidity > 60% RH, temperature > 30 °C) for 30 days.

  9. 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.

  10. Dynamics of homogeneous nucleation

    DEFF Research Database (Denmark)

    Toxværd, Søren

    2015-01-01

    The classical nucleation theory for homogeneous nucleation is formulated as a theory for a density fluctuation in a supersaturated gas at a given temperature. But molecular dynamics simulations reveal that it is small cold clusters which initiates the nucleation. The temperature in the nucleating...

  11. TrkAIII Promotes Microtubule Nucleation and Assembly at the Centrosome in SH-SY5Y Neuroblastoma Cells, Contributing to an Undifferentiated Anaplastic Phenotype

    Directory of Open Access Journals (Sweden)

    Antonietta R. Farina

    2013-01-01

    Full Text Available The alternative TrkAIII splice variant is expressed by advanced stage human neuroblastomas (NBs and exhibits oncogenic activity in NB models. In the present study, employing stable transfected cell lines and assays of indirect immunofluorescence, immunoprecipitation, Western blotting, microtubule regrowth, tubulin kinase, and tubulin polymerisation, we report that TrkAIII binds α-tubulin and promotes MT nucleation and assembly at the centrosome. This effect depends upon spontaneous TrkAIII activity, TrkAIII localisation to the centrosome and pericentrosomal area, and the capacity of TrkAIII to bind, phosphorylate, and polymerise tubulin. We propose that this novel role for TrkAIII contributes to MT involvement in the promotion and maintenance of an undifferentiated anaplastic NB cell morphology by restricting and augmenting MT nucleation and assembly at the centrosomal MTOC.

  12. Flow cytometry of nucleated red blood cells used as monitoring technique for aquatic risk assessment. A review.

    Directory of Open Access Journals (Sweden)

    Bratosin D.

    2016-05-01

    Full Text Available During the last decades anthropogenic factors led to a significant enhancement of pollutants in aquatic environment and for several years, chemicals analysis has been commonly employed. These techniques cannot detect and quantify many environmental phenomena such as bioavailability, bioaccumulation and synergistic effects. For these reasons, many investigations for evaluating the effects of xenobiotic on organisms use in vitro or in vivo bioassays. The bioassays give a global response for all chemicals present in the environment and these represent one of the best ways to estimate the risk assessment of pollutants in environment for monitoring. For assessing cytotoxicity or ecotoxicity of pollutants (heavy metals, nanoparticles, etc. and to assess aquatic pollution degree and biomonitoring of Danube River and Danube Delta, we developed a new experimental cell system based on the apoptosis of nucleated erythrocytes from fishes and batrachians which are directly exposed to pollutants absorbed by different ways. Despite their structural simplicity, the erythrocytes of lower vertebrates preserve nucleus and mitochondria, both the sensors of the programmed cell death (PCD machinery to develop an apoptosis phenomenon. Our proposed bioassays which are based on the apoptosis phenomenon as induced biomarker by pollutants on fish or amphibians erythrocytes, evidenced by flow cytometry (apoptosis/necrosis discriminated by FITC-annexin-V labeling/PI and cellular viability measured with calcein-AM method could be rapid and very sensitive tests for in laboratory aquatic risk assessment and biomonitoring. Standardization and application of these tests will surely provide the opportunity of their use easily in ecotoxicological laboratories, biomonitoring of large river basins such as the Danube River Basin and will be also able deliver information on fish as a food product.

  13. Total body irradiation in hematopoietic stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Fundagul Andic

    2014-06-01

    Full Text Available Total body irradiation is used in conjunction with chemotherapy as a conditioning regimen in the treatment of many disease such as leukemia, myelodysplastic syndrome, aplastic anemia, multiple myeloma and lymphoma prior to the hematopoetic stem cell transplantation. The main purposes of the hematopoetic stem cell transplantation are eradication of the recipient bone marrow and any residual cancer cells, creation of space in the receipient bone marrow for donor hematopoetic stem cells, and immunosuppression to prevent rejection of donor stem cells in the case of an allotransplant. [Archives Medical Review Journal 2014; 23(3.000: 398-410

  14. Evaluation of correlation between nucleated red blood cell count in term newborns and meconium-stained amniotic fluid

    Directory of Open Access Journals (Sweden)

    Esmaeilian L

    2001-09-01

    Full Text Available Considering the incidence of meconium-stained amniotic fluid (MSAF in newborns and its complications, and also based on indirect reports pointing out relationship between nucleated red blood cell (nRBC, as a marker of chronic hypoxia, and MSAF in term newborns, and in order to determine this relationship more accurately, this study was done on women with uncomplicated singleton term pregnancy that admitted for delivery at Shariati hospital in year 2000. After excluding confounding factors on nRBC, case group who includes infants with MSAF, and control group who have clear amniotic fluid were determined. Maternal age and parity, gestational age, birth weight, apgar score, neonatal out come, and FHR pattern as well as newborn hemoglobin values were evaluated. Venous cord blood was analyzed for nRBC counts per 100 WBC. Case and control groups were divided according to nRBC counts with cutoff point of 10 and then compared statistically. From the samples, 117 cases and 67 controls were evaluated. Maternal and neonatal factors were similar in two situations. Number of nRBC was 3.75±4.8 in control group and 12.04±11.7 in case group (P<0.01 and it was abnormal (>10 in 9 percent of newborns with clear fluid and 32 percent of MSAF (P<0.01. Cord blood nRBC count increased when meconium is passed intrauterine. This suggests that cases with MSAF may be at risk of chronic hypoxia. Cohort research is recommended to study the affect of delivery mode on the neonatal outcome in cases with MSAF and to evaluate the cause of fetal hypoxia in uncomplicated pregnancy with MSAF.

  15. Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions : Impact of Particle Size, Line Tension, and Surface Functionality

    NARCIS (Netherlands)

    Liu, Shanqiu; Eijkelenkamp, Rik; Duvigneau, Joost; Vancso, G. Julius

    2017-01-01

    Core-shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO2-blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell

  16. Nucleation in ZBLAN glasses

    NARCIS (Netherlands)

    de Leede, G.L.A.; Waal, de H.

    1989-01-01

    Nucleation rates were detd. in a ZrF4-BaF2-NaF-LaF3-AlF3 glass (ZBLAN) using an optical method. The results were compared with a similar glass having a slightly different compn. The difference in the nucleation rate is explained by classical nucleation theory using calcd. free-energy differences

  17. Nucleation in the atmosphere

    International Nuclear Information System (INIS)

    Hegg, D A; Baker, M B

    2009-01-01

    Small particles play major roles in modulating radiative and hydrological fluxes in the atmosphere and thus they impact both climate (IPCC 2007) and weather. Most atmospheric particles outside clouds are created in situ through nucleation from gas phase precursors and most ice particles within clouds are formed by nucleation, usually from the liquid. Thus, the nucleation process is of great significance in the Earth's atmosphere. The theoretical examination of nucleation in the atmosphere has been based mostly on classical nucleation theory. While diagnostically very useful, the prognostic skill demonstrated by this approach has been marginal. Microscopic approaches such as molecular dynamics and density functional theory have also proven useful in elucidating various aspects of the process but are not yet sufficiently refined to offer a significant prognostic advantage to the classical approach, due primarily to the heteromolecular nature of atmospheric nucleation. An important aspect of the nucleation process in the atmosphere is that the degree of metastability of the parent phase for the nucleation is modulated by a number of atmospheric processes such as condensation onto pre-existing particles, updraft velocities that are the main driving force for supersaturation of water (a major factor in all atmospheric nucleation), and photochemical production rates of nucleation precursors. Hence, atmospheric nucleation is both temporally and spatially inhomogeneous

  18. Microtubule nucleation in mouse bone marrow-derived mast cells is regulated by the concerted action of GIT1/βPIX proteins and calcium

    Czech Academy of Sciences Publication Activity Database

    Sulimenko, Vadym; Hájková, Zuzana; Černohorská, Markéta; Sulimenko, Tetyana; Sládková, Vladimíra; Dráberová, Lubica; Vinopal, Stanislav; Dráberová, Eduarda; Dráber, Pavel

    2015-01-01

    Roč. 194, č. 9 (2015), s. 4099-4111 ISSN 0022-1767 R&D Projects: GA ČR GAP302/12/1673; GA ČR GPP302/11/P709; GA ČR(CZ) GA14-09807S; GA ČR GA15-22194S; GA MŠk(CZ) LD13015; GA MŠk LH12050; GA MZd NT14467 Institutional support: RVO:68378050 Keywords : Bone Marrow-Derived Mast Cells * Microtubule Nucleation * GIT1/beta PIX Proteins * Calcium Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.985, year: 2015

  19. Radioimmunological measurements of total LH in sheep pituitary cells

    International Nuclear Information System (INIS)

    McIntosh, R.P.; McIntosh, J.E.A.

    1983-01-01

    Procedures commonly used to extract LH from pituitary cells in order to measure total cell content were compared in four cell preparations. It was shown in 81 samples of cells suspended in 1 mM EDTA or 50 mM NaHCO 3 that after freezing and thawing folloqwed by any of a variety of treatments, there were no significant differences in the amounts of LH measured by RIA relative to the arbitrarily chosen reference treatment of vigorous pipetting. The additional treatments were multiple freezing and thawing, homogenisation, sonication, homogenisation in 25-100 mM Na 2 CO 3 folloqwed by rapid neutralisation, or none. The consistency of the results suggested that the same cellular pools of LH were being made accessible for measurement with all treatments. However, use of the more vigorous conditions of 1-2.5 M urea, 1% Triton X-100, or sonication on ice in 100 mM Na 2 CO 3 decreased the amount of measurable hormone presumably due to its modification. In two cell preparations, homogenisation of cells in 100 mM Na 2 CO 3 produced and additional 45% of measurable LH not accessible using other treatments nor from the source material in two other preparations. (author)

  20. Sensitivity of ice-nucleating bacteria to ultraviolet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Obata, Hitoshi; Tanahashi, Shinji; Kawahara, Hidehisa (Kansai Univ., Suita, Osaka (Japan). Faculty of Engineering)

    1992-01-01

    The effect of ultraviolet (UV) irradiation on the ice-nucleating activity of the ice-nucleating bacteria was examined. Bacterial suspension was irradiated with UV (254 nm, 6Wx2) for 5 min at a distance of 20 cm from UV source. Although no viable cells were detected, the ice-nucreating activity of the cells was not affected. Furthermore, after UV irradiation for 3 hr, the ice-nucleating activity of Pseudomonas fluorescens and P. syringae was only slightly decreased, although that of P. viridiflava and Erwinia herbicola was significantly lowered. We succeeded in killing the ice-nucleating bacteria, while retaining their ice-nucleating activity with UV irradiation. (author).

  1. Principles of nucleation theory

    International Nuclear Information System (INIS)

    Clement, C.F.; Wood, M.H.

    1980-01-01

    The nucleation of small stable species is described in the problem of void growth by discrete rate equations. When gas is being produced the problem reduces to one of calculating the incubation dose for the gas bubble to void transition. A general expression for the steady state nucleation rate is derived for the case when voids are formed by vacancy fluctuations which enable an effective nucleation barrier to be crossed. (author)

  2. On void nucleation

    International Nuclear Information System (INIS)

    Subbotin, A.V.

    1978-01-01

    Nucleation of viable voids in irradiated materials is considered. The mechanism of evaporation and absorption of interstitials and vacancies disregarding the possibility of void merging is laid down into the basis of the discussion. The effect of irradiated material structure on void nucleation is separated from the effect of the properties of supersaturated solutions of vacancies and interstitials. An analytical expression for the nucleation rate is obtained and analyzed in different cases. The interstitials are concluded to effect severely the nucleation rate of viable voids

  3. Bromide space, total body water, and sick cell syndrome

    International Nuclear Information System (INIS)

    Schober, O.; Hundeshagen, H.; Lehr, L.

    1982-01-01

    Displacements of the bromide space (Br-82-C, as a marker for the extracellular fluid compartment) are caused by an enhanced anatomical space and/or increased permeability of cells to bromide. The ratio Br-82-C: total body water (TBW) was evaluated to be 0.83 +- 0.17 in critically ill patients (n = 38) compared with the normal value of 0.46 +- 0.04 (n = 10). Because of normal TBW in critically ill patients (TBW = 505 +- 68 ml/kg), an increased bromide penetration into cells seems to be responsible for the enlarged ratio Br-82-C: TBW. Taking into consideration measurements in patients with malabsorption (Br-82-C: TBW = 0.56 +- 0.13; n = 13) and carcinoma of the rectum and colon (Br-82-C: TBW = 0.66 +- 0.24; n = 18) we think that the bromide space is a good measurement of the effective extracellular water. (orig.)

  4. Protection of nucleated bone marrow cells of mice against effect of radiation-induced micronucleus formation by using polysaccharides extracted from 'Zi Zhi' (a ganoderma)

    International Nuclear Information System (INIS)

    Chu Fang; Luo Houliang; Luo Gui; Chen Shunle; Liu Zhifang

    1988-01-01

    This paper describes the influence of polysaccharides extracted from 'Zi Zhi' (Ganoderma Sinese Zhao, Xu et Zhang) on the frequency of micronucleated cells induced by 60 Co gamma irradiation at different doses in bone marrow of mice. These polysaccharides of 'Zi Zhi' were shown to be of ability to protect nucleated bone marrow cells from micronucleus formation in irradiated mice. For Swiss mice, a dose reduction factor (DRF) was found to be 1.72 in the range of 0 to 4.728 Gy and for LACA mice, to be 1.73 in the range of 0 to 3.152 Gy. Such findings indicate that these polysaccharides are comparable to L-cysteine in their effeciency of protection

  5. Cytoplasmic Nucleation and Atypical Branching Nucleation Generate Endoplasmic Microtubules in Physcomitrella patens[OPEN

    Science.gov (United States)

    Nakaoka, Yuki; Kimura, Akatsuki; Tani, Tomomi; Goshima, Gohta

    2015-01-01

    The mechanism underlying microtubule (MT) generation in plants has been primarily studied using the cortical MT array, in which fixed-angled branching nucleation and katanin-dependent MT severing predominate. However, little is known about MT generation in the endoplasm. Here, we explored the mechanism of endoplasmic MT generation in protonemal cells of Physcomitrella patens. We developed an assay that utilizes flow cell and oblique illumination fluorescence microscopy, which allowed visualization and quantification of individual MT dynamics. MT severing was infrequently observed, and disruption of katanin did not severely affect MT generation. Branching nucleation was observed, but it showed markedly variable branch angles and was occasionally accompanied by the transport of nucleated MTs. Cytoplasmic nucleation at seemingly random locations was most frequently observed and predominated when depolymerized MTs were regrown. The MT nucleator γ-tubulin was detected at the majority of the nucleation sites, at which a single MT was generated in random directions. When γ-tubulin was knocked down, MT generation was significantly delayed in the regrowth assay. However, nucleation occurred at a normal frequency in steady state, suggesting the presence of a γ-tubulin-independent backup mechanism. Thus, endoplasmic MTs in this cell type are generated in a less ordered manner, showing a broader spectrum of nucleation mechanisms in plants. PMID:25616870

  6. Effect of surface modification of nanofibres with glutamic acid peptide on calcium phosphate nucleation and osteogenic differentiation of marrow stromal cells.

    Science.gov (United States)

    Karaman, Ozan; Kumar, Ankur; Moeinzadeh, Seyedsina; He, Xuezhong; Cui, Tong; Jabbari, Esmaiel

    2016-02-01

    Biomineralization is mediated by extracellular matrix (ECM) proteins with amino acid sequences rich in glutamic acid. The objective of this study was to investigate the effect of calcium phosphate deposition on aligned nanofibres surface-modified with a glutamic acid peptide on osteogenic differentiation of rat marrow stromal cells. Blend of EEGGC peptide (GLU) conjugated low molecular weight polylactide (PLA) and high molecular weight poly(lactide-co-glycolide) (PLGA) was electrospun to form aligned nanofibres (GLU-NF). The GLU-NF microsheets were incubated in a modified simulated body fluid for nucleation of calcium phosphate crystals on the fibre surface. To achieve a high calcium phosphate to fibre ratio, a layer-by-layer approach was used to improve diffusion of calcium and phosphate ions inside the microsheets. Based on dissipative particle dynamics simulation of PLGA/PLA-GLU fibres, > 80% of GLU peptide was localized to the fibre surface. Calcium phosphate to fibre ratios as high as 200%, between those of cancellous (160%) and cortical (310%) bone, was obtained with the layer-by-layer approach. The extent of osteogenic differentiation and mineralization of marrow stromal cells seeded on GLU-NF microsheets was directly related to the amount of calcium phosphate deposition on the fibres prior to cell seeding. Expression of osteogenic markers osteopontin, alkaline phosphatase (ALP), osteocalcin and type 1 collagen increased gradually with calcium phosphate deposition on GLU-NF microsheets. Results demonstrate that surface modification of aligned synthetic nanofibres with EEGGC peptide dramatically affects nucleation and growth of calcium phosphate crystals on the fibres leading to increased osteogenic differentiation of marrow stromal cells and mineralization. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Three-color confocal Förster (or fluorescence) resonance energy transfer microscopy: Quantitative analysis of protein interactions in the nucleation of actin filaments in live cells.

    Science.gov (United States)

    Wallrabe, Horst; Sun, Yuansheng; Fang, Xiaolan; Periasamy, Ammasi; Bloom, George S

    2015-06-01

    Experiments using live cell 3-color Förster (or fluorescence) resonance energy transfer (FRET) microscopy and corresponding in vitro biochemical reconstitution of the same proteins were conducted to evaluate actin filament nucleation. A novel application of 3-color FRET data is demonstrated, extending the analysis beyond the customary energy-transfer efficiency (E%) calculations. MDCK cells were transfected for coexpression of Teal-N-WASP/Venus-IQGAP1/mRFP1-Rac1, Teal-N-WASP/Venus-IQGAP1/mRFP1-Cdc42, CFP-Rac1/Venus-IQGAP1/mCherry-actin, or CFP-Cdc42/Venus-IQGAP1/mCherry-actin, and with single-label equivalents for spectral bleedthrough correction. Using confirmed E% as an entry point, fluorescence levels and related ratios were correlated at discrete accumulating levels at cell peripheries. Rising ratios of CFP-Rac1:Venus-IQGAP1 were correlated with lower overall actin fluorescence, whereas the CFP-Cdc42:Venus-IQGAP1 ratio correlated with increased actin fluorescence at low ratios, but was neutral at higher ratios. The new FRET analyses also indicated that rising levels of mRFP1-Cdc42 or mRFP1-Rac1, respectively, promoted or suppressed the association of Teal-N-WASP with Venus-IQGAP1. These 3-color FRET assays further support our in vitro results about the role of IQGAP1, Rac1, and Cdc42 in actin nucleation, and the differential impact of Rac1 and Cdc42 on the association of N-WASP with IQGAP1. In addition, this study emphasizes the power of 3-color FRET as a systems biology strategy for simultaneous evaluation of multiple interacting proteins in individual live cells. © 2015 International Society for Advancement of Cytometry.

  8. Diamond Nucleation Using Polyethene

    Science.gov (United States)

    Morell, Gerardo (Inventor); Makarov, Vladimir (Inventor); Varshney, Deepak (Inventor); Weiner, Brad (Inventor)

    2013-01-01

    The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

  9. Void nucleation at heterogeneities

    International Nuclear Information System (INIS)

    Seyyedi, S.A.; Hadji-Mirzai, M.; Russell, K.C.

    The energetics and kinetics of void nucleation at dislocations and interfaces are analyzed. These are potential void nucleation sites only when they are not point defect sinks. Both kinds of site are found to be excellent catalysts in the presence of inert gas

  10. Structural Basis of Actin Filament Nucleation by Tandem W Domains

    Science.gov (United States)

    Chen, Xiaorui; Ni, Fengyun; Tian, Xia; Kondrashkina, Elena; Wang, Qinghua; Ma, Jianpeng

    2013-01-01

    SUMMARY Spontaneous nucleation of actin is very inefficient in cells. To overcome this barrier, cells have evolved a set of actin filament nucleators to promote rapid nucleation and polymerization in response to specific stimuli. However, the molecular mechanism of actin nucleation remains poorly understood. This is hindered largely by the fact that actin nucleus, once formed, rapidly polymerizes into filament, thus making it impossible to capture stable multisubunit actin nucleus. Here, we report an effective double-mutant strategy to stabilize actin nucleus by preventing further polymerization. Employing this strategy, we solved the crystal structure of AMPPNP-actin in complex with the first two tandem W domains of Cordon-bleu (Cobl), a potent actin filament nucleator. Further sequence comparison and functional studies suggest that the nucleation mechanism of Cobl is probably shared by the p53 cofactor JMY, but not Spire. Moreover, the double-mutant strategy opens the way for atomic mechanistic study of actin nucleation and polymerization. PMID:23727244

  11. Control of PbI2 nucleation and crystallization: towards efficient perovskite solar cells based on vapor-assisted solution process

    Science.gov (United States)

    Yang, Chongqiu; Peng, Yanke; Simon, Terrence; Cui, Tianhong

    2018-04-01

    Perovskite solar cells (PSC) have outstanding potential to be low-cost, high-efficiency photovoltaic devices. The PSC can be fabricated by numerous techniques; however, the power conversion efficiency (PCE) for the two-step-processed PSC falls behind that of the one-step method. In this work, we investigate the effects of relative humidity (RH) and dry air flow on the lead iodide (PbI2) solution deposition process. We conclude that the quality of the PbI2 film is critical to the development of the perovskite film and the performance of the PSC device. Low RH and dry air flow used during the PbI2 spin coating procedure can increase supersaturation concentration to form denser PbI2 nuclei and a more suitable PbI2 film. Moreover, airflow-assisted PbI2 drying and thermal annealing steps can smooth transformation from the nucleation stage to the crystallization stage.

  12. Predictive Value of Nucleated Red Blood Cell Counts in Cord and Peripheral Blood of Asphyxiated Term Neonates in the First Week of Life

    Directory of Open Access Journals (Sweden)

    B Bahman Bijari

    2010-03-01

    Full Text Available Introduction: Increased numbers of nucleated red blood cells (NRBC circulating in the blood of neonates can be associated with relative hypoxia and adverse outcomes. Thus, the aim of this study was to assess the NRBC count during the first week of life in neonates diagnosed with asphyxia as compared to healthy neonates and to determine the short-term morbidity and mortality for the affected babies. Methods: The cross-sectional study compared 15 healthy neonates with 15 neonates diagnosed with asphyxia confirmed by pH of cord blood or Apgar scores. The nucleated red blood cell (NRBC counts were calculated right after birth, and on days 3 and 7, and the hematological parameters of umbilical cord blood were also evaluated. The infants were followed for mortality and associated morbidity. Statistical analysis was conducted using the Mann-Whitney U test, analysis of variance, chi-square tests, and Pearson’s correlation coefficient. A p-value < 0.05 was considered as statistically significant. Results: The initial NRBC counts were significantly higher in the asphyxiated group than in the control group and the difference remained significant through the end of first week. All of the umbilical cord blood parameters were significantly lower in the study group and were negatively correlated with the NRBC count. At birth, higher NRBC count correlated with higher mortality. conclution: Results show that NRBC count is a useful predictive factor for neonatal asphyxia through the end of the first week of life, although a larger study population and a longer follow up period seems to be necessary.

  13. Evaporation rate of nucleating clusters.

    Science.gov (United States)

    Zapadinsky, Evgeni

    2011-11-21

    The Becker-Döring kinetic scheme is the most frequently used approach to vapor liquid nucleation. In the present study it has been extended so that master equations for all cluster configurations are included into consideration. In the Becker-Döring kinetic scheme the nucleation rate is calculated through comparison of the balanced steady state and unbalanced steady state solutions of the set of kinetic equations. It is usually assumed that the balanced steady state produces equilibrium cluster distribution, and the evaporation rates are identical in the balanced and unbalanced steady state cases. In the present study we have shown that the evaporation rates are not identical in the equilibrium and unbalanced steady state cases. The evaporation rate depends on the number of clusters at the limit of the cluster definition. We have shown that the ratio of the number of n-clusters at the limit of the cluster definition to the total number of n-clusters is different in equilibrium and unbalanced steady state cases. This causes difference in evaporation rates for these cases and results in a correction factor to the nucleation rate. According to rough estimation it is 10(-1) by the order of magnitude and can be lower if carrier gas effectively equilibrates the clusters. The developed approach allows one to refine the correction factor with Monte Carlo and molecular dynamic simulations.

  14. Effects of Grain Boundaries and Dislocation Cell Walls on Void Nucleation and Growth in Aluminium during Fast Neutron Irradiation

    DEFF Research Database (Denmark)

    Horsewell, Andy; Rahman, F. A.; Singh, Bachu Narain

    1983-01-01

    and growth occurs in a zone extending up to 10 mu m from grain boundaries in annealed material. In polygonized material, the presence of dislocation cell walls leads to cell size dependent void formation and growth; the swelling rate in the large cells is substantially higher than in the annealed material....

  15. Gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

  16. Gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

  17. Dimers in nucleating vapors

    Science.gov (United States)

    Lushnikov, A. A.; Kulmala, M.

    1998-09-01

    The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).

  18. Return to nucleate boiling

    International Nuclear Information System (INIS)

    Shumway, R.W.

    1985-01-01

    This paper presents a collection of TMIN (temperature of return to nucleate boiling) correlations, evaluates them under several conditions, and compares them with a wide range of data. Purpose is to obtain the best one for use in a water reactor safety computer simulator known as TRAC-B. Return to nucleate boiling can occur in a reactor accident at either high or low pressure and flow rates. Most of the correlations yield unrealistic results under some conditions. A new correlation is proposed which overcomes many of the deficiencies

  19. Stereological estimation of total cell numbers in the young human utricular macula

    DEFF Research Database (Denmark)

    Severinsen, Stig Avall; Sørensen, Mads Sølvsten; Kirkegaard, Mette

    2010-01-01

    Abstract Conclusion: There is no change in the total cell population and hair cell:supporting cell ratio in the human utricular macula from gestational week 16 and onwards, whereas the lower hair cell:supporting cell ratio and lower total number of cells in the youngest specimens indicate...... that the utricle is still differentiating and adding new cells at the 10th to 12th gestational week. Objectives: Archival temporal bones were investigated to quantify cell numbers in the utricular macula in fetuses and children. Methods: The age of the subjects ranged from gestational week 10 to 15 years....... The optical fractionator was used to estimate the total number of cells in the utricular macula. Results: The total cell number was found to be 143 000 in subjects older than gestational week 16. The number of hair cells and supporting cells did not change between the 16th gestational week and 15 years...

  20. Nonequilibrium thermodynamics of nucleation

    NARCIS (Netherlands)

    Schweizer, M.; Sagis, L.M.C.

    2014-01-01

    We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a

  1. AEROSOL NUCLEATION AND GROWTH DURING LAMINAR TUBE FLOW: MAXIMUM SATURATIONS AND NUCLEATION RATES. (R827354C008)

    Science.gov (United States)

    An approximate method of estimating the maximum saturation, the nucleation rate, and the total number nucleated per second during the laminar flow of a hot vapour–gas mixture along a tube with cold walls is described. The basis of the approach is that the temperature an...

  2. Homogeneous crystal nucleation in polymers.

    Science.gov (United States)

    Schick, C; Androsch, R; Schmelzer, J W P

    2017-11-15

    The pathway of crystal nucleation significantly influences the structure and properties of semi-crystalline polymers. Crystal nucleation is normally heterogeneous at low supercooling, and homogeneous at high supercooling, of the polymer melt. Homogeneous nucleation in bulk polymers has been, so far, hardly accessible experimentally, and was even doubted to occur at all. This topical review summarizes experimental findings on homogeneous crystal nucleation in polymers. Recently developed fast scanning calorimetry, with cooling and heating rates up to 10 6 K s -1 , allows for detailed investigations of nucleation near and even below the glass transition temperature, including analysis of nuclei stability. As for other materials, the maximum homogeneous nucleation rate for polymers is located close to the glass transition temperature. In the experiments discussed here, it is shown that polymer nucleation is homogeneous at such temperatures. Homogeneous nucleation in polymers is discussed in the framework of the classical nucleation theory. The majority of our observations are consistent with the theory. The discrepancies may guide further research, particularly experiments to progress theoretical development. Progress in the understanding of homogeneous nucleation is much needed, since most of the modelling approaches dealing with polymer crystallization exclusively consider homogeneous nucleation. This is also the basis for advancing theoretical approaches to the much more complex phenomena governing heterogeneous nucleation.

  3. A unified kinetic approach to binary nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Kevrekidis, P.G. [Department of Physics, Rutgers University, 136 Frelinghuysen Road]|[E.O.H.S.I., Rutgers University]|[UMDNJ, 170 Frelinghuysen Road, Piscataway, New Jersey 08854-8019 (United States); Lazaridis, M. [Norwegian Institute for Air Research (NILU), Instittutvein 18, P. O. Box 100, N-2007 Kjeller (Norway); Drossinos, Y. [European Commission, Joint Research Centre, I-21020 Ispra (Vatican City State, Holy See) (Italy); Georgopoulos, P.G. [E.O.H.S.I., Rutgers University]|[UMDNJ, 170 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States)

    1999-11-01

    Two different methods to calculate the steady-state nucleation rate in heteromolecular systems proposed by Stauffer (1976) and Langer (1969) are analyzed. Their mathematical equivalence is explicitly demonstrated, thereby obtaining a generic expression for the rate of binary nucleation. Its numerical evaluation does not entail rotation of the coordinate system at the saddle point, but it only requires data in the natural coordinate system of number fluctuations, namely molecular impingement rates, the droplet free energy and its second order derivatives at the saddle point, and the total density of condensible vapors. {copyright} {ital 1999 American Institute of Physics.}

  4. Trapping crystal nucleation of cholesterol monohydrate

    DEFF Research Database (Denmark)

    Solomonov, I.; Weygand, M.J.; Kjær, K.

    2005-01-01

    Crystalline nucleation of cholesterol at the air-water interface has been studied via grazing incidence x-ray diffraction using synchrotron radiation. The various stages of cholesterol molecular assembly from monolayer to three bilayers incorporating interleaving hydrogen-bonded water layers......, at least initially, an intralayer cholesterol rearrangement in a single-crystal-to-single-crystal transition. The preferred nucleation of the monoclinic phase of cholesterol . H2O followed by transformation to the stable monohydrate phase may be associated with an energetically more stable cholesterol...... bilayer arrangement of the former and a more favorable hydrogen-bonding arrangement of the latter. The relevance of this nucleation process of cholesterol monohydrate to pathological crystallization of cholesterol from cell biomembranes is discussed....

  5. Overview: Nucleation of clathrate hydrates.

    Science.gov (United States)

    Warrier, Pramod; Khan, M Naveed; Srivastava, Vishal; Maupin, C Mark; Koh, Carolyn A

    2016-12-07

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  6. Overview: Nucleation of clathrate hydrates

    Science.gov (United States)

    Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

    2016-12-01

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  7. Heterogeneous ice nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, A. [Helsinki Univ. (Finland). Dept. of Physics

    1994-12-31

    The classical theory of heterogenous ice nucleation is reviewed in detail. The modelling of ice nucleation in the adsorbed water films on natural particles by analogous ice nucleation in adsorbed water films on the walls of porous media is discussed. Ice nucleation in adsorbed films of purewater and the HNO{sub 3}/H{sub 2}0 binary system on the surface of porous aerosol (SiO{sub 2}) was investigated using the method of NMR spectroscopy. The median freezing temperature and freezing temperature region were shown to be highly sensitive both to the average thickness of the adsorbed films and to the amount of adsorbed nitric acid. The character of the ice phase formation tends to approach that of bulk liquid with increasing adsorbed film thickness. Under the given conditions the thickness of the adsorbed films decreases with an increasing amount of adsorbed nitric acid molecules The molar concentration of nitric acid in the adsorbed films is very small (of the order of 10{sup -}3 10{sup -}2 (M/l)). Nitric acid molecules tend to adsorb on the surface of aerosol to a greater extent than in subsequent layers. The concentration is greatest in layers situated close to the surface and sharply decreases with the distance from the surface. The difference between the median freezing temperatures for adsorbed pure water and for the binary system was found to be about 9 K for films of equal thickness. This is about 150 times greater than the difference between the median freezing temperatures of bulk pure water and a solution with the same concentration of nitric acid. (orig.)

  8. Nucleation in Synoptically Forced Cirrostratus

    Science.gov (United States)

    Lin, R.-F.; Starr, D. OC.; Reichardt, J.; DeMott, P. J.

    2004-01-01

    Formation and evolution of cirrostratus in response to weak, uniform and constant synoptic forcing is simulated using a one-dimensional numerical model with explicit microphysics, in which the particle size distribution in each grid box is fully resolved. A series of tests of the model response to nucleation modes (homogeneous-freezing-only/heterogeneous nucleation) and heterogeneous nucleation parameters are performed. In the case studied here, nucleation is first activated in the prescribed moist layer. A continuous cloud-top nucleation zone with a depth depending on the vertical humidity gradient and one of the nucleation parameters is developed afterward. For the heterogeneous nucleation cases, intermittent nucleation zones in the mid-upper portion of the cloud form where the relative humidity is on the rise, because existent ice crystals do not uptake excess water vapor efficiently, and ice nuclei (IN) are available. Vertical resolution as fine as 1 m is required for realistic simulation of the homogeneous-freezing-only scenario, while the model resolution requirement is more relaxed in the cases where heterogeneous nucleation dominates. Bulk microphysical and optical properties are evaluated and compared. Ice particle number flux divergence, which is due to the vertical gradient of the gravity-induced particle sedimentation, is constantly and rapidly changing the local ice number concentration, even in the nucleation zone. When the depth of the nucleation zone is shallow, particle number concentration decreases rapidly as ice particles grow and sediment away from the nucleation zone. When the depth of the nucleation zone is large, a region of high ice number concentration can be sustained. The depth of nucleation zone is an important parameter to be considered in parametric treatments of ice cloud generation.

  9. Nucleation of recrystallization in fine-grained materials: an extension of the Bailey-Hirsch criterion

    Science.gov (United States)

    Favre, Julien; Fabrègue, Damien; Chiba, Akihiko; Bréchet, Yves

    2013-11-01

    A new criterion for nucleation in the case of dynamic recrystallization is proposed in order to include the contribution of the grain boundary energy stored in the microstructure in the energy balance. Due to the nucleation events, the total surface area of pre-existing grain boundaries decreases, leading to a nucleus size smaller than expected by conventional nucleation criteria. The new model provides a better prediction of the nucleus size during recrystallization of pure copper compared with the conventional nucleation criterion.

  10. Use of a commercially available nucleating agent to control the morphological development of solution-processed small molecule bulk heterojunction organic solar cells

    KAUST Repository

    Sharenko, Alexander; Treat, Neil D.; Love, John A.; Toney, Michael F.; Stingelin, Natalie; Nguyen, Thuc-Quyen

    2014-01-01

    © the Partner Organisations 2014. The nucleating agent DMDBS is used to modulate the crystallization of solution-processed small molecule donor molecules in bulk heterojunction organic photovoltaic (BHJ OPV) devices. This control over donor molecule crystallization leads to a reduction in optimized thermal annealing times as well as smaller donor molecule crystallites, and therefore more efficient devices, when using an excessive amount of solvent additive. We therefore demonstrate the use of nucleating agents as a powerful and versatile processing strategy for solution-processed, small molecule BHJ OPVs. This journal is

  11. Use of a commercially available nucleating agent to control the morphological development of solution-processed small molecule bulk heterojunction organic solar cells

    KAUST Repository

    Sharenko, Alexander

    2014-08-12

    © the Partner Organisations 2014. The nucleating agent DMDBS is used to modulate the crystallization of solution-processed small molecule donor molecules in bulk heterojunction organic photovoltaic (BHJ OPV) devices. This control over donor molecule crystallization leads to a reduction in optimized thermal annealing times as well as smaller donor molecule crystallites, and therefore more efficient devices, when using an excessive amount of solvent additive. We therefore demonstrate the use of nucleating agents as a powerful and versatile processing strategy for solution-processed, small molecule BHJ OPVs. This journal is

  12. On the Ice Nucleation Spectrum

    Science.gov (United States)

    Barahona, D.

    2012-01-01

    This work presents a novel formulation of the ice nucleation spectrum, i.e. the function relating the ice crystal concentration to cloud formation conditions and aerosol properties. The new formulation is physically-based and explicitly accounts for the dependency of the ice crystal concentration on temperature, supersaturation, cooling rate, and particle size, surface area and composition. This is achieved by introducing the concepts of ice nucleation coefficient (the number of ice germs present in a particle) and nucleation probability dispersion function (the distribution of ice nucleation coefficients within the aerosol population). The new formulation is used to generate ice nucleation parameterizations for the homogeneous freezing of cloud droplets and the heterogeneous deposition ice nucleation on dust and soot ice nuclei. For homogeneous freezing, it was found that by increasing the dispersion in the droplet volume distribution the fraction of supercooled droplets in the population increases. For heterogeneous ice nucleation the new formulation consistently describes singular and stochastic behavior within a single framework. Using a fundamentally stochastic approach, both cooling rate independence and constancy of the ice nucleation fraction over time, features typically associated with singular behavior, were reproduced. Analysis of the temporal dependency of the ice nucleation spectrum suggested that experimental methods that measure the ice nucleation fraction over few seconds would tend to underestimate the ice nuclei concentration. It is shown that inferring the aerosol heterogeneous ice nucleation properties from measurements of the onset supersaturation and temperature may carry significant error as the variability in ice nucleation properties within the aerosol population is not accounted for. This work provides a simple and rigorous ice nucleation framework where theoretical predictions, laboratory measurements and field campaign data can be

  13. Immature germ cells in semen - correlation with total sperm count and sperm motility.

    Science.gov (United States)

    Patil, Priya S; Humbarwadi, Rajendra S; Patil, Ashalata D; Gune, Anita R

    2013-07-01

    Current data regarding infertility suggests that male factor contributes up to 30% of the total cases of infertility. Semen analysis reveals the presence of spermatozoa as well as a number of non-sperm cells, presently being mentioned in routine semen report as "round cells" without further differentiating them into leucocytes or immature germ cells. The aim of this work was to study a simple, cost-effective, and convenient method for differentiating the round cells in semen into immature germ cells and leucocytes and correlating them with total sperm counts and motility. Semen samples from 120 males, who had come for investigation for infertility, were collected, semen parameters recorded, and stained smears studied for different round cells. Statistical analysis of the data was done to correlate total sperm counts and sperm motility with the occurrence of immature germ cells and leucocytes. The average shedding of immature germ cells in different groups with normal and low sperm counts was compared. The clinical significance of "round cells" in semen and their differentiation into leucocytes and immature germ cells are discussed. Round cells in semen can be differentiated into immature germ cells and leucocytes using simple staining methods. The differential counts mentioned in a semen report give valuable and clinically relevant information. In this study, we observed a negative correlation between total count and immature germ cells, as well as sperm motility and shedding of immature germ cells. The latter was statistically significant with a P value 0.000.

  14. Molecular dynamics simulation of bubble nucleation in explosive boiling

    International Nuclear Information System (INIS)

    Zou Yu; Chinese Academy of Sciences, Beijing; Huai Xiulan; Liang Shiqiang

    2009-01-01

    Molecular dynamics (MD) simulation is carried out for the bubble nucleation of liquid nitrogen in explosive boiling. The heat is transferred into the simulation system by rescaling the velocity of the molecules. The results indicate that the initial equilibrium temperature of liquid and molecular cluster size affect the energy conversion in the process of bubble nucleation. The potential energy of the system violently varies at the beginning of the bubble nucleation, and then varies around a fixed value. At the end of bubble nucleation, the potential energy of the system slowly increases. In the bubble nucleation of explosive boiling, the lower the initial equilibrium temperature, the larger the size of the molecular cluster, and the more the heat transferred into the system of the simulation cell, causing the increase potential energy in a larger range. (authors)

  15. Nucleation phenomena at Suzuki phases

    International Nuclear Information System (INIS)

    Acosta-Najarro, D.; Jose Y, M.

    1982-01-01

    Crystal of NaCl doped with Mn present regions with an increase in nucleation densities when observed by surface gold decoration; this increase is related to the nucleation of the Suzuki phases which are induced by cooling of the crystal matrix. Calculations based on atomistic nucleation theory are developed to explain the increased nucleation density. Experiments were made to compare with the theoretical results. In particular the density of nuclei was measured as a function of the rate or arrival of atoms to the surface. Therefore, the changes in the nucleation densities are explained in terms of change in migration energies between the Suzuki phase and the NaCl matrix excluding the possibility of nucleation induced by point defects. (author)

  16. Nucleate boiling heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Saiz Jabardo, J.M. [Universidade da Coruna (Spain). Escola Politecnica Superior], e-mail: mjabardo@cdf.udc.es

    2009-07-01

    Nucleate boiling heat transfer has been intensely studied during the last 70 years. However boiling remains a science to be understood and equated. In other words, using the definition given by Boulding, it is an 'insecure science'. It would be pretentious of the part of the author to explore all the nuances that the title of the paper suggests in a single conference paper. Instead the paper will focus on one interesting aspect such as the effect of the surface microstructure on nucleate boiling heat transfer. A summary of a chronological literature survey is done followed by an analysis of the results of an experimental investigation of boiling on tubes of different materials and surface roughness. The effect of the surface roughness is performed through data from the boiling of refrigerants R-134a and R-123, medium and low pressure refrigerants, respectively. In order to investigate the extent to which the surface roughness affects boiling heat transfer, very rough surfaces (4.6 {mu}m and 10.5 {mu}m ) have been tested. Though most of the data confirm previous literature trends, the very rough surfaces present a peculiar behaviour with respect to that of the smoother surfaces (Ra<3.0 {mu}m). (author)

  17. Nucleate boiling heat transfer

    International Nuclear Information System (INIS)

    Saiz Jabardo, J.M.

    2009-01-01

    Nucleate boiling heat transfer has been intensely studied during the last 70 years. However boiling remains a science to be understood and equated. In other words, using the definition given by Boulding, it is an 'insecure science'. It would be pretentious of the part of the author to explore all the nuances that the title of the paper suggests in a single conference paper. Instead the paper will focus on one interesting aspect such as the effect of the surface microstructure on nucleate boiling heat transfer. A summary of a chronological literature survey is done followed by an analysis of the results of an experimental investigation of boiling on tubes of different materials and surface roughness. The effect of the surface roughness is performed through data from the boiling of refrigerants R-134a and R-123, medium and low pressure refrigerants, respectively. In order to investigate the extent to which the surface roughness affects boiling heat transfer, very rough surfaces (4.6 μm and 10.5 μm ) have been tested. Though most of the data confirm previous literature trends, the very rough surfaces present a peculiar behaviour with respect to that of the smoother surfaces (Ra<3.0 μm). (author)

  18. Estimation of the total number of mast cells in the human umbilical cord. A methodological study

    DEFF Research Database (Denmark)

    Engberg Damsgaard, T M; Windelborg Nielsen, B; Sørensen, Flemming Brandt

    1992-01-01

    The aim of the present study was to estimate the total number of mast cells in the human umbilical cord. Using 50 microns-thick paraffin sections, made from a systematic random sample of umbilical cord, the total number of mast cells per cord was estimated using a combination of the optical...... disector and fractionated sampling. The mast cell of the human umbilical cord was found in Wharton's jelly, most frequently in close proximity to the three blood vessels. No consistent pattern of variation in mast cell numbers from the fetal end of the umbilical cord towards the placenta was seen....... The total number of mast cells found in the umbilical cord was 5,200,000 (median), range 2,800,000-16,800,000 (n = 7), that is 156,000 mast cells per gram umbilical cord (median), range 48,000-267,000. Thus, the umbilical cord constitutes an adequate source of mast cells for further investigation...

  19. Immature germ cells in semen ? correlation with total sperm count and sperm motility

    OpenAIRE

    Patil, Priya S.; Humbarwadi, Rajendra S.; Patil, Ashalata D.; Gune, Anita R.

    2013-01-01

    Background: Current data regarding infertility suggests that male factor contributes up to 30% of the total cases of infertility. Semen analysis reveals the presence of spermatozoa as well as a number of non-sperm cells, presently being mentioned in routine semen report as "round cells" without further differentiating them into leucocytes or immature germ cells. Aim: The aim of this work was to study a simple, cost-effective, and convenient method for differentiating the round cells in se...

  20. Immature germ cells in semen - correlation with total sperm count and sperm motility

    Directory of Open Access Journals (Sweden)

    Priya S Patil

    2013-01-01

    Conclusions: Round cells in semen can be differentiated into immature germ cells and leucocytes using simple staining methods. The differential counts mentioned in a semen report give valuable and clinically relevant information. In this study, we observed a negative correlation between total count and immature germ cells, as well as sperm motility and shedding of immature germ cells. The latter was statistically significant with a P value 0.000.

  1. Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

    Science.gov (United States)

    Wang, Bingbing; China, Swarup; Knopf, Daniel; Gilles, Mary; Laskin, Alexander

    2016-04-01

    Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

  2. Nucleation of (4)R brane universes

    International Nuclear Information System (INIS)

    Cordero, Ruben; Rojas, EfraIn

    2004-01-01

    The creation of brane universes induced by a totally antisymmetric tensor living in a fixed background spacetime is presented, where a term involving the intrinsic curvature of the brane is considered. A canonical quantum mechanical approach employing the Wheeler-DeWitt equation is used. The probability nucleation for the brane is calculated by means of the corresponding instanton and the WKB approximation. Some cosmological implications from the model are presented

  3. Nucleation of {sup (4)}R brane universes

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, Ruben [Departamento de FIsica, Escuela Superior de FIsica y Matematicas del IPN, Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, DF (Mexico); Rojas, EfraIn [Facultad de FIsica e Inteligencia Artificial, Universidad Veracruzana, Sebastian Camacho 5, Xalapa, Veracruz, 91000 (Mexico)

    2004-09-07

    The creation of brane universes induced by a totally antisymmetric tensor living in a fixed background spacetime is presented, where a term involving the intrinsic curvature of the brane is considered. A canonical quantum mechanical approach employing the Wheeler-DeWitt equation is used. The probability nucleation for the brane is calculated by means of the corresponding instanton and the WKB approximation. Some cosmological implications from the model are presented.

  4. Homogeneous versus heterogeneous zeolite nucleation

    NARCIS (Netherlands)

    Dokter, W.H.; Garderen, van H.F.; Beelen, T.P.M.; Santen, van R.A.; Bras, W.

    1995-01-01

    Aggregates of fractal dimension were found in the intermediate gel phases that organize prior to nucleation and crystallization (shown right) of silicalite from a homogeneous reaction mixture. Small- and wide-angle X-ray scattering studies prove that for zeolites nucleation may be homogeneous or

  5. On Capillary Rise and Nucleation

    Science.gov (United States)

    Prasad, R.

    2008-01-01

    A comparison of capillary rise and nucleation is presented. It is shown that both phenomena result from a balance between two competing energy factors: a volume energy and a surface energy. Such a comparison may help to introduce nucleation with a topic familiar to the students, capillary rise. (Contains 1 table and 3 figures.)

  6. Theory and Simulation of Nucleation

    NARCIS (Netherlands)

    Kuipers, J.|info:eu-repo/dai/nl/304832049

    2009-01-01

    Nucleation is the process where a stable nucleus spontaneously emerges in a metastable environment. Examples of nucleation abound, for instance the formation of droplets in undercooled gasses and of crystals in undercooled liquids. The process is thermally activated and is key to understanding

  7. A dynamical theory of nucleation

    Science.gov (United States)

    Lutsko, James F.

    2013-05-01

    A dynamical theory of nucleation based on fluctuating hydrodynamics is described. It is developed in detail for the case of diffusion-limited nucleation appropriate to colloids and macro-molecules in solution. By incorporating fluctuations, realistic fluid-transport and realistic free energy models the theory is able to give a unified treatment of both the pre-critical development of fluctuations leading to a critical cluster as well as of post-critical growth. Standard results from classical nucleation theory are shown to follow in the weak noise limit while the generality of the theory allows for many extensions including the description of very high supersaturations (small clusters), multiple order parameters and strong-noise effects to name a few. The theory is applied to homogeneous and heterogeneous nucleation of a model globular protein in a confined volume and it is found that nucleation depends critically on the existence of long-wavelength, small-amplitude density fluctuations.

  8. Nucleation of holin domains and holes optimizes lysis timing of E. coli by phage λ

    Science.gov (United States)

    Ryan, Gillian; Rutenberg, Andrew

    2007-03-01

    Holin proteins regulate the precise scheduling of Escherichia coli lysis during infection by bacteriophage λ. Inserted into the host bacterium's inner membrane during infection, holins aggregate to form rafts and then holes within those rafts. We present a two-stage nucleation model of holin action, with the nucleation of condensed holin domains followed by the nucleation of holes within these domains. Late nucleation of holin rafts leads to a weak dependence of lysis timing on host cell size, though both nucleation events contribute equally to timing errors. Our simulations recover the accurate scheduling observed experimentally, and also suggest that phage-λ lysis of E.coli is optimized.

  9. Analysis of cell flow and cell loss following X-irradiation using sequential investigation of the total number of cells in the various parts of the cell cycle

    International Nuclear Information System (INIS)

    Skog, S.; Tribukait, B.

    1985-01-01

    The cell flow and cell loss of an in vivo growing Ehrlich ascites tumour were calculated by sequential estimation of changes in total number of cells in the cell cycle compartments. Normal growth was compared with the grossly disturbed cell flow evident after a 5 Gy X-irradiation. The doubling time of normal, exponentially growing cells was 24 hr. The generation time was 21 hr and the potential doubling time was 21 hr. Thus, the growth fraction was 1.0 and the cell loss rate about 0.5%/hr. Following irradiation, a transiently increased relative outflow rate from all cell cycle compartments was found at about 3 and 40 hr, and from S phase at 24 hr after irradiation. Increase in cell loss as well as non-viable cells was observed at 24 hr after irradiation at the time of release of the irradiation-induced G 2 blockage. The experiments show the applicability and limitations of cell flow and cell loss calculations by sequential analysis of the total number of cells in the various parts of the cell cycle. (author)

  10. Protein crystal nucleation in pores.

    Science.gov (United States)

    Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E

    2017-01-16

    The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the pore is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the pore walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.

  11. M cells and granular mononuclear cells in Peyer's patch domes of mice depleted of their lymphocytes by total lymphoid irradiation

    International Nuclear Information System (INIS)

    Ermak, T.H.; Steger, H.J.; Strober, S.; Owen, R.L.

    1989-01-01

    The cytoarchitecture of Peyer's patches that were depleted of their lymphocytes by total lymphoid irradiation (TLI) was examined with particular attention to the effects on M cells in the follicle epithelium and on mononuclear cells in follicle domes underlying the epithelium. Five-month-old, specific pathogen-free Balb/c mice were irradiated with 200-250 rad/day, five times a week to a total dose of 3400-4250, and their Peyer's patches were either fixed for electron microscopy or frozen for immunohistochemistry 1-4 days after completion of irradiation. Control mice were examined at the same time intervals. Follicle domes of TLI mice had approximately one fourth the epithelial surface area of domes of control mice. Within the epithelium, lymphoid cells were virtually depleted after TLI, and yet the epithelium contained M cells. In control mice, most M cells were accompanied by lymphoid cells in invaginations of the apical-lateral cell membrane. In TLI mice, most M cells did not have such apical-lateral invaginations and were columnar shaped. Other than lacking lymphocytes, these cells appeared to be mature M cells. Some M cells did have lymphoid cells or granular mononuclear cells below their basal membranes, adjacent to the basal lamina. Below the epithelium, the proportion of granular mononuclear cells was greatly increased following TLI. The retention of M cells and the increase in proportion of granular mononuclear cells in follicle domes are consistent with selective depletion of lymphocytes following TLI. Persistence of M cells without lymphocytic invaginations after TLI suggests that M cells can differentiate in the absence of, or at least in the presence of very few, lymphocytes, and that invagination by lymphocytes is not necessary to maintain mature M cell morphology

  12. Superheating in nucleate boiling calculated by the heterogeneous nucleation theory

    International Nuclear Information System (INIS)

    Gerum, E.; Straub, J.; Grigull, U.

    1979-01-01

    With the heterogeneous nucleation theory the superheating of the liquid boundary layer in nucleate boiling is described not only for the onset of nuclear boiling but also for the boiling crisis. The rate of superheat depends on the thermodynamic stability of the metastable liquid, which is influenced by the statistical fluctuations in the liquid and the nucleation at the solid surface. Because of the fact that the cavities acting as nuclei are too small for microscopic observation, the size and distribution function of the nuclei on the surface necessary for the determination of the probability of bubble formation cannot be detected by measuring techniques. The work of bubble formation reduced by the nuclei can be represented by a simple empirical function whose coefficients are determined from boiling experiments. Using this the heterogeneous nucleation theory describes the superheating of the liquid. Several fluids including refrigerants, liquid gases, organic liquids and water were used to check the theory. (author)

  13. Metadynamics studies of crystal nucleation

    Science.gov (United States)

    Giberti, Federico; Salvalaglio, Matteo; Parrinello, Michele

    2015-01-01

    Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation. PMID:25866662

  14. Metadynamics studies of crystal nucleation

    Directory of Open Access Journals (Sweden)

    Federico Giberti

    2015-03-01

    Full Text Available Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation.

  15. Review: The nucleation of disorder

    International Nuclear Information System (INIS)

    Cahn, R.W.; Johnson, W.L.

    1986-01-01

    Four types of phase transformation that involve the conversion of crystalline phases into more disordered forms are reviewed: melting, disordering of superlattices, amorphization by diffusion between crystalline phases, and irradation amorphization. In the review emphasis is placed on evidence for the heterogeneous nucleation of the product phases; in this connection, the role of surfaces, antiphase domain boundaries, dislocations, vacancies, and grain boundaries is specifically discussed. All of these features have been either observed, or hypothesized, to play a role as heterogeneous nucleation sites in one or more of the four transformations. An attempt is made to draw parallels between nucleation mechanisms in the various processes

  16. [Effect of ERK1/2 Signaling Pathway Inhibitor PD98059 on the Expression of Ras, BRaf, MEK, ERK1/2 in Marrow Nucleated Red Blood Cells of CMS Patients].

    Science.gov (United States)

    Han, Yuan-Fang; Ji, Lin-Hua; Feng, Ting-Ting; Liu, Fang; Cui, Sen; Su, Juan

    2017-10-01

    To investigate the effect of ERK1 / 2 signaling pathway inhibitor PD98059 on Ras, Raf, MEK, ERK1, ERK2 expression in order to explore a new way for basic research and clinical treatment of the chronic mountain sickness(CMS). Sixteen CMS patients were selected, the bone marrow was collected for isolation of monomuclear cells (MNC), the cells were sorted by using CD71 and CD235a antibody magnetic beads, then positive cells were diveded into 5 groups: blank control, DMSO and PD98059 5, 10 and 20 µmol/L, and were cultured in hypoxid condition for 72 hours. The Ras-GTP levels in supernatant was detected by ELISA, the RT-PCR was used to determine the expression of BRaf, MEK, ERK1, ERK2 mRNA in nucleated red blood cells, and the Western blot method was used to detect expression of BRaf, MEK, ERK1, ERK2 protein. PD98059 had no effect on the level of Ras-GTP in each groups. Compared with the blank control group, the expression levels of BRaf, MEK mRNA in DMSO group were not statistically significant (P values were 0.826, 0.298). Compared with the PD98059 20 mol/L group, the expression level of ERK1/2 mRNA was statistically significant (P=0.001, 0.002). Compared with the blank control group, expression levels of p-BRaf, p-MEK protein in DMSO group were not statistically significant (P=0.370, 0.351). Compared with the PD98059 20 mol/L group, the difference of p-ERK1/2 protein level in other 4 groups were statistically significant (P values were <0.001, 0.007). PD98059 can up-regulate the expressions of ERK1/2 miRNA and p-ERK1/2 protein in bone marrow nucleated red blood cells, the Ras / Raf / MEK / ERK 1/2 pathway is the main signal transduction pathway in regulating bone marrow nucleated red blood cells, suggesting that Ras/Raf /MEK /ERK 1/2 pathway may be involved in the pathogenesis of chronic mountain sickness process.

  17. Computer simulation of chemical nucleation

    International Nuclear Information System (INIS)

    Turner, J.S.

    1979-01-01

    The problem of nucleation at chemical instabilities is investigated by means of microscopic computer simulation. The first-order transition of interest involves a new kind of nucleation arising from chemical transformations rather than physical forces. Here it is the chemical state of matter, and not matter itself, which is spatially localized to form the nucleus for transition between different chemical states. First, the concepts of chemical instability, nonequilibrium phase transition, and dissipative structure are reviewed briefly. Then recently developed methods of reactive molecular dynamics are used to study chemical nucleation in a simple model chemical reactions. Finally, the connection of these studies to nucleation and condensation processes involving physical and chemical interactions is explored. (orig.)

  18. A marine biogenic source of atmospheric ice-nucleating particles

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T. W.; Ladino, L. A.; Alpert, Peter A.; Breckels, M. N.; Brooks, I. M.; Browse, J.; Burrows, Susannah M.; Carslaw, K. S.; Huffman, J. A.; Judd, C.; Kilthau, W. P.; Mason, R. H.; McFiggans, Gordon; Miller, L. A.; Najera, J.; Polishchuk, E. A.; Rae, S.; Schiller, C. L.; Si, M.; Vergara Temprado, J.; Whale, Thomas; Wong, J P S; Wurl, O.; Yakobi-Hancock, J. D.; Abbatt, JPD; Aller, Josephine Y.; Bertram, Allan K.; Knopf, Daniel A.; Murray, Benjamin J.

    2015-09-09

    The formation of ice in clouds is facilitated by the presence of airborne ice nucleating particles1,2. Sea spray is one of the major global sources of atmospheric particles, but it is unclear to what extent these particles are capable of nucleating ice3–11. Here we show that material in the sea surface microlayer, which is enriched in surface active organic material representative of that found in sub-micron sea- spray aerosol12–21, nucleates ice under conditions that occur in mixed-phase clouds and high-altitude ice clouds. The ice active material is likely biogenic and is less than ~0.2 ?m in size. We also show that organic material (exudate) released by a common marine diatom nucleates ice when separated from cells and propose that organic material associated with phytoplankton cell exudates are a candidate for the observed ice nucleating ability of the microlayer samples. By combining our measurements with global model simulations of marine organic aerosol, we show that ice nucleating particles of marine origin are dominant in remote marine environments, such as the Southern Ocean, the North Pacific and the North Atlantic.

  19. Unscheduled DNA synthesis in spleen cells of mice exposed to low doses of total body irradiation

    International Nuclear Information System (INIS)

    Tuschl, H.; Kovac, R.; Hruby, E.

    1983-07-01

    Unscheduled DNA synthesis was induced by UV irradiation of spleen cells obtained from C 57 Bl mice after repeated total body irradiation of 0.05 Gy 60 Co (0.00125 Gy/mice) and determined autoradiographically. An enhancement in the ability for repair of UV induced DNA lesions was observed in cells of gamma irradiated animals. While the amount of 3 H-thymidine incorporated per cell was increased, the percentage of labeled cells remained unchanged. The present results are compared with previous data on low dose radiation exposure in men. (Author) [de

  20. Single cell adhesion strength assessed with variable-angle total internal reflection fluorescence microscopy

    Directory of Open Access Journals (Sweden)

    Marcelina Cardoso Dos Santos

    2017-06-01

    Full Text Available We propose a new strategy to evaluate adhesion strength at the single cell level. This approach involves variable-angle total internal reflection fluorescence microscopy to monitor in real time the topography of cell membranes, i.e. a map of the membrane/substrate separation distance. According to the Boltzmann distribution, both potential energy profile and dissociation energy related to the interactions between the cell membrane and the substrate were determined from the membrane topography. We have highlighted on glass substrates coated with poly-L-lysine and fibronectin, that the dissociation energy is a reliable parameter to quantify the adhesion strength of MDA-MB-231 motile cells.

  1. Role of nucleation in nanodiamond film growth

    International Nuclear Information System (INIS)

    Lifshitz, Y.; Lee, C.H.; Wu, Y.; Zhang, W.J.; Bello, I.; Lee, S.T.

    2006-01-01

    Nanodiamond films were deposited using different microwave plasma chemical vapor deposition schemes following several nucleation pretreatment methods. The nucleation efficiency and the films structure were investigated using scanning and transmission electron microscopy and Raman spectroscopy. C 2 dimer growth (CH 4 and H 2 in 90% Ar) cannot nucleate diamond and works only on existing diamond surfaces. The methyl radical process (up to 20% CH 4 in H 2 ) allows some nucleation probability on appropriate substrates. Prolonged bias enhanced nucleation initiates both diamond nucleation and growth. C 2 dimer growth results in pure nanodiamond free of amorphous carbon, while prolonged bias enhanced nucleation forms an amorphous carbon/nanodiamond composite

  2. Two types of amorphous protein particles facilitate crystal nucleation.

    Science.gov (United States)

    Yamazaki, Tomoya; Kimura, Yuki; Vekilov, Peter G; Furukawa, Erika; Shirai, Manabu; Matsumoto, Hiroaki; Van Driessche, Alexander E S; Tsukamoto, Katsuo

    2017-02-28

    Nucleation, the primary step in crystallization, dictates the number of crystals, the distribution of their sizes, the polymorph selection, and other crucial properties of the crystal population. We used time-resolved liquid-cell transmission electron microscopy (TEM) to perform an in situ examination of the nucleation of lysozyme crystals. Our TEM images revealed that mesoscopic clusters, which are similar to those previously assumed to consist of a dense liquid and serve as nucleation precursors, are actually amorphous solid particles (ASPs) and act only as heterogeneous nucleation sites. Crystalline phases never form inside them. We demonstrate that a crystal appears within a noncrystalline particle assembling lysozyme on an ASP or a container wall, highlighting the role of heterogeneous nucleation. These findings represent a significant departure from the existing formulation of the two-step nucleation mechanism while reaffirming the role of noncrystalline particles. The insights gained may have significant implications in areas that rely on the production of protein crystals, such as structural biology, pharmacy, and biophysics, and for the fundamental understanding of crystallization mechanisms.

  3. Total sensitivity and uncertainty analysis for LWR pin-cells with improved UNICORN code

    International Nuclear Information System (INIS)

    Wan, Chenghui; Cao, Liangzhi; Wu, Hongchun; Shen, Wei

    2017-01-01

    Highlights: • A new model is established for the total sensitivity and uncertainty analysis. • The NR approximation applied in S&U analysis can be avoided by the new model. • Sensitivity and uncertainty analysis is performed to PWR pin-cells by the new model. • The effects of the NR approximation for the PWR pin-cells are quantified. - Abstract: In this paper, improvements to the multigroup cross-section perturbation model have been proposed and applied in the self-developed UNICORN code, which is capable of performing the total sensitivity and total uncertainty analysis for the neutron-physics calculations by applying the direct numerical perturbation method and the statistical sampling method respectively. The narrow resonance (NR) approximation was applied in the multigroup cross-section perturbation model, implemented in UNICORN. As improvements to the NR approximation to refine the multigroup cross-section perturbation model, an ultrafine-group cross-section perturbation model has been established, in which the actual perturbations are applied to the ultrafine-group cross-section library and the reconstructions of the resonance cross sections are performed by solving the neutron slowing-down equation. The total sensitivity and total uncertainty analysis were then applied to the LWR pin-cells, using both the multigroup and the ultrafine-group cross-section perturbation models. The numerical results show that the NR approximation overestimates the relative sensitivity coefficients and the corresponding uncertainty results for the LWR pin-cells, and the effects of the NR approximation are significant for σ_(_n_,_γ_) and σ_(_n_,_e_l_a_s_) of "2"3"8U. Therefore, the effects of the NR approximation applied in the total sensitivity and total uncertainty analysis for the neutron-physics calculations of LWR should be taken into account.

  4. Mammalian amyloidogenic proteins promote prion nucleation in yeast.

    Science.gov (United States)

    Chandramowlishwaran, Pavithra; Sun, Meng; Casey, Kristin L; Romanyuk, Andrey V; Grizel, Anastasiya V; Sopova, Julia V; Rubel, Aleksandr A; Nussbaum-Krammer, Carmen; Vorberg, Ina M; Chernoff, Yury O

    2018-03-02

    Fibrous cross-β aggregates (amyloids) and their transmissible forms (prions) cause diseases in mammals (including humans) and control heritable traits in yeast. Initial nucleation of a yeast prion by transiently overproduced prion-forming protein or its (typically, QN-rich) prion domain is efficient only in the presence of another aggregated (in most cases, QN-rich) protein. Here, we demonstrate that a fusion of the prion domain of yeast protein Sup35 to some non-QN-rich mammalian proteins, associated with amyloid diseases, promotes nucleation of Sup35 prions in the absence of pre-existing aggregates. In contrast, both a fusion of the Sup35 prion domain to a multimeric non-amyloidogenic protein and the expression of a mammalian amyloidogenic protein that is not fused to the Sup35 prion domain failed to promote prion nucleation, further indicating that physical linkage of a mammalian amyloidogenic protein to the prion domain of a yeast protein is required for the nucleation of a yeast prion. Biochemical and cytological approaches confirmed the nucleation of protein aggregates in the yeast cell. Sequence alterations antagonizing or enhancing amyloidogenicity of human amyloid-β (associated with Alzheimer's disease) and mouse prion protein (associated with prion diseases), respectively, antagonized or enhanced nucleation of a yeast prion by these proteins. The yeast-based prion nucleation assay, developed in our work, can be employed for mutational dissection of amyloidogenic proteins. We anticipate that it will aid in the identification of chemicals that influence initial amyloid nucleation and in searching for new amyloidogenic proteins in a variety of proteomes. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Kim Myung K

    2011-09-01

    Full Text Available Abstract Background Total internal reflection fluorescence microscopy (TIRFM is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology. Results Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein and clathrin light chain (a vesicle coat protein support our theoretical analysis. Conclusions These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana.

  6. Label free imaging of cell-substrate contacts by holographic total internal reflection microscopy.

    Science.gov (United States)

    Mandracchia, Biagio; Gennari, Oriella; Marchesano, Valentina; Paturzo, Melania; Ferraro, Pietro

    2017-09-01

    The study of cell adhesion contacts is pivotal to understand cell mechanics and interaction at substrates or chemical and physical stimuli. We designed and built a HoloTIR microscope for label-free quantitative phase imaging of total internal reflection. Here we show for the first time that HoloTIR is a good choice for label-free study of focal contacts and of cell/substrate interaction as its sensitivity is enhanced in comparison with standard TIR microscopy. Finally, the simplicity of implementation and relative low cost, due to the requirement of less optical components, make HoloTIR a reasonable alternative, or even an addition, to TIRF microscopy for mapping cell/substratum topography. As a proof of concept, we studied the formation of focal contacts of fibroblasts on three substrates with different levels of affinity for cell adhesion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Regulation of microtubule nucleation mediated by gamma-tubulin complexes

    Czech Academy of Sciences Publication Activity Database

    Sulimenko, Vadym; Hájková, Zuzana; Klebanovych, Anastasiya; Dráber, Pavel

    2017-01-01

    Roč. 254, č. 3 (2017), s. 1187-1199 ISSN 0033-183X R&D Projects: GA MŠk(CZ) LD13015 Institutional support: RVO:68378050 Keywords : mitotic spindle formation * ring complex * fission yeast * organizing centers * protein complex * golgi-complex * cell-cycle * pole body * augmin * centrosome * Centrosomes * Microtubule nucleation * Microtubule-organizing centers * Non-centrosomal nucleation sites * Spindle pole bodies * gamma-Tubulin complexes Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Cell biology Impact factor: 2.870, year: 2016

  8. Evaluation of the Total Cost of Ownership of Fuel Cell-Powered Material Handling Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Ramsden, T.

    2013-04-01

    This report discusses an analysis of the total cost of ownership of fuel cell-powered and traditional battery-powered material handling equipment (MHE, or more typically 'forklifts'). A number of fuel cell MHE deployments have received funding support from the federal government. Using data from these government co-funded deployments, DOE's National Renewable Energy Laboratory (NREL) has been evaluating the performance of fuel cells in material handling applications. NREL has assessed the total cost of ownership of fuel cell MHE and compared it to the cost of ownership of traditional battery-powered MHE. As part of its cost of ownership assessment, NREL looked at a range of costs associated with MHE operation, including the capital costs of battery and fuel cell systems, the cost of supporting infrastructure, maintenance costs, warehouse space costs, and labor costs. Considering all these costs, NREL found that fuel cell MHE can have a lower overall cost of ownership than comparable battery-powered MHE.

  9. Characterization of corneal pannus removed from patients with total limbal stem cell deficiency.

    Science.gov (United States)

    Espana, Edgar M; Di Pascuale, Mario A; He, Hua; Kawakita, Tetsuya; Raju, Vadrevu K; Liu, Chia-Yang; Tseng, Scheffer C G

    2004-09-01

    To determine the epithelial lineage of origin in corneal pannus tissue surgically removed from patients with total limbal stem cell (SC) deficiency. The lineage of origin of the entire conjunctivalized pannus removed from eight corneas with a diagnosis of total limbal SC deficiency was characterized by anti-keratin (K)-3 and anti-K19 monoclonal antibodies. The protein and mRNA of epithelial outgrowth from segments of five such pannus specimens were analyzed by Western blot and reverse transcription-polymerase chain reaction, respectively. Cross sections of all eight specimens showed a stratified epithelium with goblet cells expressing mucin (MUC)-5AC, and a stroma showing blood vessels and inflammatory cell infiltrates. Immunostaining showed full-thickness expression of K19 in the entire pannus of all eight specimens. Expression of K3 was negative in seven patients, but was sporadically positive in a patient with Stevens-Johnson syndrome. In culture, all five pannus specimens generated a compact, small epithelial cell outgrowth, and except for one, reached confluence in 2 to 3 weeks. The K3/K12 pair was expressed by extracts of cell outgrowth from the control limbal epithelial explant, but not in all five pannus specimens. A 60-kDa band of DeltaNp63 was expressed in the control specimen and in all five pannus specimens. Cell outgrowth expressed K3 transcript in three, but none showed K12 transcript. The resultant epithelial phenotype of the pannus tissue was not corneal, as evidenced by the negative staining to cornea-specific K12 mRNA and protein, but was conjunctival, as evidenced by the presence of goblet cells, the weak expression of K3, and the strong expression of K19. The abundant expression of DeltaNp63 in such conjunctiva-derived epithelium in eyes with total limbal SC deficiency raises doubts as to its validity as a limbal SC marker. Copyright Association for Research in Vision and Ophthalmology

  10. Nucleation and cavitation in parahydrogen

    International Nuclear Information System (INIS)

    Pi, Martí; Barranco, Manuel; Navarro, Jesús; Ancilotto, Francesco

    2012-01-01

    Highlights: ► We have constructed a density functional (DF) for parahydrogen between 14 and 32 K. ► The experimental equation of state and the surface tension are well reproduced. ► We have investigated nucleation and cavitations processes in the metastable phase. ► We have obtained the electron bubble explosion within the capillary model. - Abstract: We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model.

  11. A classical density functional investigation of nucleation

    International Nuclear Information System (INIS)

    Ghosh, Satinath; Ghosh, Swapan K.

    2009-01-01

    Study of nucleation and growth phenomena in condensation is of prime importance in various applications such as crystal growth, nanoparticle synthesis, pattern formation etc. The knowledge of nucleation barrier in condensation is necessary to control the nucleation kinetics, size of the nanoparticles etc. Classical nucleation theory (CNT) assumes the density of the drop as bulk density irrespective of the size of the drop and overestimates the nucleation barrier. Here we are interested in solving the problem analytically using density functional theory (DFT) with square gradient approximation along the lines of Cahn and Hilliard. Nucleation barrier and density profile obtained in this work are consistent with other works based on nonclassical theory. (author)

  12. The role of confined collagen geometry in decreasing nucleation energy barriers to intrafibrillar mineralization.

    Science.gov (United States)

    Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros; Jun, Young-Shin

    2018-03-06

    Mineralization of collagen is critical for the mechanical functions of bones and teeth. Calcium phosphate nucleation in collagenous structures follows distinctly different patterns in highly confined gap regions (nanoscale confinement) than in less confined extrafibrillar spaces (microscale confinement). Although the mechanism(s) driving these differences are still largely unknown, differences in the free energy for nucleation may explain these two mineralization behaviors. Here, we report on experimentally obtained nucleation energy barriers to intra- and extrafibrillar mineralization, using in situ X-ray scattering observations and classical nucleation theory. Polyaspartic acid, an extrafibrillar nucleation inhibitor, increases interfacial energies between nuclei and mineralization fluids. In contrast, the confined gap spaces inside collagen fibrils lower the energy barrier by reducing the reactive surface area of nuclei, decreasing the surface energy penalty. The confined gap geometry, therefore, guides the two-dimensional morphology and structure of bioapatite and changes the nucleation pathway by reducing the total energy barrier.

  13. Branching microtubule nucleation in Xenopus egg extracts mediated by augmin and TPX2

    Science.gov (United States)

    Petry, Sabine; Groen, Aaron C.; Ishihara, Keisuke; Mitchison, Timothy J.; Vale, Ronald D.

    2013-01-01

    Summary The microtubules that comprise mitotic spindles in animal cells are nucleated at centrosomes and by spindle assembly factors that are activated in the vicinity of chromatin. Indirect evidence also has suggested that microtubules might be nucleated from pre-existing microtubules throughout the spindle, but this process has not been observed directly. Here, we demonstrate microtubule nucleation from the sides of existing microtubules in meiotic Xenopus egg extracts. Daughter microtubules grow at a low branch angle and with the same polarity as mother filaments. Branching microtubule nucleation requires gamma-tubulin and augmin and is stimulated by GTP-bound Ran and its effector TPX2, factors previously implicated in chromatin-stimulated nucleation. Because of the rapid amplification of microtubule numbers and the preservation of microtubule polarity, microtubule-dependent microtubule nucleation is well suited for spindle assembly and maintenance. PMID:23415226

  14. Urediospores of Puccinia spp. and other rusts are warm-temperature ice nucleators and harbor ice nucleation active bacteria

    Science.gov (United States)

    Morris, C. E.; Sands, D. C.; Glaux, C.; Samsatly, J.; Asaad, S.; Moukahel, A. R.; Gonçalves, F. L. T.; Bigg, E. K.

    2012-10-01

    In light of various features of the biology of the rust fungi and of the epidemiology of the plant diseases they cause that illustrate the important role of rainfall in their life history, we have characterized the ice nucleation activity (INA) of the aerially disseminated spores (urediospores) of this group of fungi. Urediospores of this obligate plant parasite were collected from natural infections from 7 species of weeds in France, from coffee in Brazil and from field and greenhouse-grown wheat in France, the USA, Turkey and Syria. Immersion freezing was used to determine freezing onset temperatures and the abundance of ice nuclei in suspensions of washed spores. Microbiological analyses of spores and subsequent tests of the ice nucleation activity of the bacteria associated with spores were deployed to quantify the contribution of bacteria to the ice nucleation activity of the spores. All samples of spores were ice nucleation active having freezing onset temperatures as warm as -4 °C. Spores in most of the samples carried cells of ice nucleation-active strains of the bacterium Pseudomonas syringae (at rates of less than 1 bacterial cell per 100 urediospores), but bacterial INA accounted for only a small fraction of the INA observed in spore suspensions. Changes in the INA of spore suspensions after treatment with lysozyme suggest that the INA of urediospores involves a polysaccharide. Based on data from the literature, we have estimated the concentrations of urediospores in air at cloud height and in rainfall. These quantities are very similar to those reported for other biological ice nucleators in these same substrates. We suggest that air sampling techniques have ignored the spatial and temporal variability of atmospheric concentrations that occur under conditions propitious for precipitation that could increase their local abundance intermittently. Nevertheless, we propose that the relative low abundance of warm-temperature biological ice nucleators in the

  15. Nanograting-based plasmon enhancement for total internal reflection fluorescence microscopy of live cells

    International Nuclear Information System (INIS)

    Kim, Kyujung; Cho, Eun-Jin; Suh, Jin-Suck; Huh, Yong-Min; Kim, Donghyun; Kim, Dong Jun

    2009-01-01

    We investigated evanescent field enhancement based on subwavelength nanogratings for improved sensitivity in total internal reflection microscopy of live cells. The field enhancement is associated with subwavelength-grating-coupled plasmon excitation. An optimum sample employed a silver grating on a silver film and an SF10 glass substrate. Field intensity was enhanced by approximately 90% when measured by fluorescent excitation of microbeads relative to that on a bare prism as a control, which is in good agreement with numerical results. The subwavelength-grating-mediated field enhancement was also applied to live cell imaging of quantum dots, which confirmed the sensitivity enhancement qualitatively.

  16. Nuclear fragmentation by nucleation approach

    International Nuclear Information System (INIS)

    Chung, K.C.

    1992-01-01

    The nucleation model is used to simulate nuclear fragmentation processes. The critical value of the effective interaction radius is shown to vary linearly with the expansion factor α. The calculated mass and charge distributions are compared with some experimental data. (author)

  17. TOTAL NUMBER, DISTRIBUTION, AND PHENOTYPE OF CELLS EXPRESSING CHONDROITIN SULPHATE PROTEOGLYCANS IN THE NORMAL HUMAN AMYGDALA

    Science.gov (United States)

    Pantazopoulos, Harry; Murray, Elisabeth A.; Berretta, Sabina

    2009-01-01

    Chondroitin sulphate proteoglycans (CSPGs) are a key structural component of the brain extracellular matrix. They are involved in critical neurodevelopmental functions and are one of the main components of pericellular aggregates known as perineuronal nets. As a step toward investigating their functional and pathophysiological roles in the human amygdala, we assessed the pattern of CSPG expression in the normal human amygdala using wisteria floribunda agglutinin (WFA) lectin-histochemistry. Total numbers of WFA-labeled elements were measured in the lateral (LN), basal (BN), accessory basal (ABN) and cortical (CO) nuclei of the amygdala from 15 normal adult human subjects. For interspecies qualitative comparison, we also investigated the pattern of WFA labeling in the amygdala of naïve rats (n=32) and rhesus monkeys (Macaca mulatta; n=6). In human amygdala, WFA lectin-histochemistry resulted in labeling of perineuronal nets and cells with clear glial morphology, while neurons did not show WFA-labeling. Total numbers of WFA-labeled glial cells showed high interindividual variability. These cells aggregated in clusters with a consistent between-subjects spatial distribution. In a subset of human subjects (n=5), dual color fluorescence using an antibody raised against glial fibrillary acidic protein (GFAP) and WFA showed that the majority (93.7%) of WFA-labeled glial cells correspond to astrocytes. In rat and monkey amygdala, WFA histochemistry labeled perineuronal nets, but not glial cells. These results suggest that astrocytes are the main cell type expressing CSPGs in the adult human amygdala. Their highly segregated distribution pattern suggests that these cells serve specialized functions within human amygdalar nuclei. PMID:18374308

  18. Study of molasses / vinasse waste ratio for single cell protein and total microorganisms

    Directory of Open Access Journals (Sweden)

    Marcia Luciana Cazetta

    2006-02-01

    Full Text Available Different molasses/ vinasse ratio were used as substrate to investigate single cell protein and total lipids production by five microorganisms: four yeasts strains: Candida lipolytica, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, a yeast isolated from vinasse lake (denominated LLV98 and a bacterium strain, Corynebacterium glutamicum. The media utilized were: a 50% molasses and 50% vinasse; b 25% molasses and 75% vinasse and c 75% molasses and 25% vinasse. The objective of this work was to study the growth of microorganisms and also evaluate protein and lipids content in the biomass obtained from these by-products. The highest single cell protein production was obtained by S. cerevisiae, 50.35%, followed by R. mucilaginosa, 41.96%. The lowest productions were obtained by C. glutamicum. The higher total lipids productions, more than 26%, were founded in molasses plus vinasse at 50%/50% by S. cerevisiae and C. glutamicum.

  19. Electrostatics Control Actin Filament Nucleation and Elongation Kinetics*

    Science.gov (United States)

    Crevenna, Alvaro H.; Naredi-Rainer, Nikolaus; Schönichen, André; Dzubiella, Joachim; Barber, Diane L.; Lamb, Don C.; Wedlich-Söldner, Roland

    2013-01-01

    The actin cytoskeleton is a central mediator of cellular morphogenesis, and rapid actin reorganization drives essential processes such as cell migration and cell division. Whereas several actin-binding proteins are known to be regulated by changes in intracellular pH, detailed information regarding the effect of pH on the actin dynamics itself is still lacking. Here, we combine bulk assays, total internal reflection fluorescence microscopy, fluorescence fluctuation spectroscopy techniques, and theory to comprehensively characterize the effect of pH on actin polymerization. We show that both nucleation and elongation are strongly enhanced at acidic pH, with a maximum close to the pI of actin. Monomer association rates are similarly affected by pH at both ends, although dissociation rates are differentially affected. This indicates that electrostatics control the diffusional encounter but not the dissociation rate, which is critical for the establishment of actin filament asymmetry. A generic model of protein-protein interaction, including electrostatics, explains the observed pH sensitivity as a consequence of charge repulsion. The observed pH effect on actin in vitro agrees with measurements of Listeria propulsion in pH-controlled cells. pH regulation should therefore be considered as a modulator of actin dynamics in a cellular environment. PMID:23486468

  20. Electrostatics control actin filament nucleation and elongation kinetics.

    Science.gov (United States)

    Crevenna, Alvaro H; Naredi-Rainer, Nikolaus; Schönichen, André; Dzubiella, Joachim; Barber, Diane L; Lamb, Don C; Wedlich-Söldner, Roland

    2013-04-26

    The actin cytoskeleton is a central mediator of cellular morphogenesis, and rapid actin reorganization drives essential processes such as cell migration and cell division. Whereas several actin-binding proteins are known to be regulated by changes in intracellular pH, detailed information regarding the effect of pH on the actin dynamics itself is still lacking. Here, we combine bulk assays, total internal reflection fluorescence microscopy, fluorescence fluctuation spectroscopy techniques, and theory to comprehensively characterize the effect of pH on actin polymerization. We show that both nucleation and elongation are strongly enhanced at acidic pH, with a maximum close to the pI of actin. Monomer association rates are similarly affected by pH at both ends, although dissociation rates are differentially affected. This indicates that electrostatics control the diffusional encounter but not the dissociation rate, which is critical for the establishment of actin filament asymmetry. A generic model of protein-protein interaction, including electrostatics, explains the observed pH sensitivity as a consequence of charge repulsion. The observed pH effect on actin in vitro agrees with measurements of Listeria propulsion in pH-controlled cells. pH regulation should therefore be considered as a modulator of actin dynamics in a cellular environment.

  1. Ice nucleation properties of mineral dusts

    OpenAIRE

    Steinke, Isabelle

    2013-01-01

    Ice nucleation in clouds has a significant impact on the global hydrological cycle as well as on the radiative budget of the Earth. The AIDA cloud chamber was used to investigate the ice nucleation efficiency of various atmospherically relevant mineral dusts. From experiments with Arizona Test Dust (ATD) a humidity and temperature dependent ice nucleation active surface site density parameterization was developed to describe deposition nucleation at temperatures above 220 K. Based...

  2. Nucleation in Polymers and Soft Matter

    Science.gov (United States)

    Xu, Xiaofei; Ting, Christina L.; Kusaka, Isamu; Wang, Zhen-Gang

    2014-04-01

    Nucleation is a ubiquitous phenomenon in many physical, chemical, and biological processes. In this review, we describe recent progress on the theoretical study of nucleation in polymeric fluids and soft matter, including binary mixtures (polymer blends, polymers in poor solvents, compressible polymer-small molecule mixtures), block copolymer melts, and lipid membranes. We discuss the methodological development for studying nucleation as well as novel insights and new physics obtained in the study of the nucleation behavior in these systems.

  3. Total bacterial count and somatic cell count in refrigerated raw milk stored in communal tanks

    Directory of Open Access Journals (Sweden)

    Edmar da Costa Alves

    2014-09-01

    Full Text Available The current industry demand for dairy products with extended shelf life has resulted in new challenges for milk quality maintenance. The processing of milk with high bacterial counts compromises the quality and performance of industrial products. The study aimed to evaluate the total bacteria counts (TBC and somatic cell count (SCC in 768 samples of refrigerated raw milk, from 32 communal tanks. Samples were collected in the first quarter of 2010, 2011, 2012 and 2013 and analyzed by the Laboratory of Milk Quality - LQL. Results showed that 62.5%, 37.5%, 15.6% and 27.1% of the means for TBC in 2010, 2011, 2012 and 2013, respectively, were above the values established by legislation. However, we observed a significant reduction in the levels of total bacterial count (TBC in the studied periods. For somatic cell count, 100% of the means indicated values below 600.000 cells/mL, complying with the actual Brazilian legislation. The values found for the somatic cell count suggests the adoption of effective measures for the sanitary control of the herd. However, the results must be considered with caution as it highlights the need for quality improvements of the raw material until it achieves reliable results effectively.

  4. Homogeneous nucleation of water in synthetic air

    NARCIS (Netherlands)

    Fransen, M.A.L.J.; Sachteleben, E.; Hruby, J.; Smeulders, D.M.J.; DeMott, P.J.; O'Dowd, C.D.

    2013-01-01

    Homogeneous nucleation rates for water vapor in synthetic air are measured by means of a Pulse-Expansion Wave Tube (PEWT). A comparison of the experimental nucleation rates with the Classical Nucleation Theory (CNT) shows that a more elaborated model is necessary to describe supercooled water

  5. A classical view on nonclassical nucleation

    NARCIS (Netherlands)

    Smeets, P.J.M.; Finney, A.R.; Habraken, W.J.E.M.; Nudelman, F.; Friedrich, H.; Laven, J.; De Yoreo, J.J.; Rodger, P.M.; Sommerdijk, N.A.J.M.

    2017-01-01

    Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO3) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO3 nucleation is still a

  6. Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

    Science.gov (United States)

    Lisle, John T.; Robbins, Lisa L.

    2016-01-01

    Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (nucleation of calcium carbonate in seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC

  7. Correlation of total body potassium and leukemic cell mass in patients with chronic lymphocytic leukemia

    International Nuclear Information System (INIS)

    Chandra, P.; Sawitsky, A.; Chanana, A.D.; Chikkappa, G.; Cohn, S.H.; Rai, K.R.; Cronkity, E.P.

    1979-01-01

    Total body leukemic mass in patients with chronic lymphocytic leukemia (CLL) was measured by quantitation of total body potassium (TBK) with a whole-body counter. In addition, the predicted normal total body potassium (Kp) for each patient was calculated from an empirically derived relationship involving height, weight age, and sex. Both the absolute TBK and the relative excess of total body potassium (TBK/Kp) were related to the stage of disease. Patients in the early stages of CLL were found to have lower TBK and TBK/Kp than patients in the late stages of disease. Both of these parameters increased with the successively advanced stages of the disease. The clinically monitored reduction of leukemic cell mass following therapy was accompanied by reductions in TBK and TBK/Kp. Data presented support the notion that TBK/Kp is a useful indicator of the total body leukemic mass. Futhermore, the results of these studies quantitatively validate the proposed clinical staging system for CLL. Quantitation of TBK by a whole-body counter is an accurate and noninvasive procedure and does not require administration of isotopes

  8. Time- and dose-dependent effects of total-body ionizing radiation on muscle stem cells

    Science.gov (United States)

    Masuda, Shinya; Hisamatsu, Tsubasa; Seko, Daiki; Urata, Yoshishige; Goto, Shinji; Li, Tao-Sheng; Ono, Yusuke

    2015-01-01

    Exposure to high levels of genotoxic stress, such as high-dose ionizing radiation, increases both cancer and noncancer risks. However, it remains debatable whether low-dose ionizing radiation reduces cellular function, or rather induces hormetic health benefits. Here, we investigated the effects of total-body γ-ray radiation on muscle stem cells, called satellite cells. Adult C57BL/6 mice were exposed to γ-radiation at low- to high-dose rates (low, 2 or 10 mGy/day; moderate, 50 mGy/day; high, 250 mGy/day) for 30 days. No hormetic responses in proliferation, differentiation, or self-renewal of satellite cells were observed in low-dose radiation-exposed mice at the acute phase. However, at the chronic phase, population expansion of satellite cell-derived progeny was slightly decreased in mice exposed to low-dose radiation. Taken together, low-dose ionizing irradiation may suppress satellite cell function, rather than induce hormetic health benefits, in skeletal muscle in adult mice. PMID:25869487

  9. Refractive Index Imaging of Cells with Variable-Angle Near-Total Internal Reflection (TIR) Microscopy.

    Science.gov (United States)

    Bohannon, Kevin P; Holz, Ronald W; Axelrod, Daniel

    2017-10-01

    The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle. By analyzing the angular position of that edge at each location in the field of view, the local refractive index can be estimated. In addition, by analyzing the steepness of the edge, the distance-to-substrate can be determined. We apply the technique to liquid calibration samples, silica beads, cultured Chinese hamster ovary cells, and primary culture chromaffin cells. The optical technique suffers from decremented lateral resolution, scattering, and interference artifacts. However, it still provides reasonable results for both refractive index (~1.38) and for distance-to-substrate (~150 nm) for the cells, as well as a lateral resolution to about 1 µm.

  10. The XMAP215 Ortholog Alp14 Promotes Microtubule Nucleation in Fission Yeast.

    Science.gov (United States)

    Flor-Parra, Ignacio; Iglesias-Romero, Ana Belén; Chang, Fred

    2018-06-04

    The organization and number of microtubules (MTs) in a cell depend on the proper regulation of MT nucleation. Currently, the mechanism of nucleation is the most poorly understood aspect of MT dynamics. XMAP215/chTOG/Alp14/Stu2 proteins are MT polymerases that stimulate MT polymerization at MT plus ends by binding and releasing tubulin dimers. Although these proteins also localize to MT organizing centers and have nucleating activity in vitro, it is not yet clear whether these proteins participate in MT nucleation in vivo. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, the XMAP215 ortholog Alp14 is critical for efficient MT nucleation in vivo. In multiple assays, loss of Alp14 function led to reduced nucleation rate and numbers of interphase MT bundles. Conversely, activation of Alp14 led to increased nucleation frequency. Alp14 associated with Mto1 and γ-tubulin complex components, and artificially targeting Alp14 to the γ-tubulin ring complexes (γ-TuRCs) stimulated nucleation. In imaging individual nucleation events, we found that Alp14 transiently associated with a γ-tubulin particle shortly before the appearance of a new MT. The transforming acidic coiled-coil (TACC) ortholog Alp7 mediated the localization of Alp14 at nucleation sites but not plus ends, and was required for efficient nucleation but not for MT polymerization. Our findings provide the strongest evidence to date that Alp14 serves as a critical MT nucleation factor in vivo. We suggest a model in which Alp14 associates with the γ-tubulin complex in an Alp7-dependent manner to facilitate the assembly or stabilization of the nascent MT. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Total Hip Arthroplasty in Patients With Avascular Necrosis After Hematopoietic Stem Cell Transplantation.

    Science.gov (United States)

    Vijapura, Anita; Levine, Harlan B; Donato, Michele; Hartzband, Mark A; Baker, Melissa; Klein, Gregg R

    2018-03-01

    The immunosuppressive regimens required for hematopoietic stem cell transplantation predispose recipients to complications, including avascular necrosis. Cancer-related comorbidities, immunosuppression, and poor bone quality theoretically increase the risk for perioperative medical complications, infection, and implant-related complications in total joint arthroplasty. This study reviewed 20 primary total hip arthroplasties for avascular necrosis in 14 patients. Outcomes were assessed at routine clinical visits and Harris hip scores were calculated. Follow-up radiographs were evaluated for component malposition, loosening, polyethylene wear, and osteolysis. Average follow-up was 44.5 months for all patients. Postoperative clinical follow-up revealed good to excellent outcomes, with significant improvement in functional outcome scores. There were no periprosthetic infections or revisions for aseptic loosening. There was 1 dislocation on postoperative day 40, which was treated successfully with a closed reduction. Two patients with a prior history of venous thromboembolism developed a pulmonary embolus on postoperative day 13 and 77, respectively. Four patients died several months to years after arthroplasty of complications unrelated to the surgical procedure. Total hip arthroplasty can both be safely performed and greatly improve quality of life in recipients of hematopoietic stem cell transplantation who develop avascular necrosis. However, prolonged venous thromboembolism prophylaxis should be carefully considered in this high-risk patient population. [Orthopedics. 2018; 41(2):e257-e261.]. Copyright 2018, SLACK Incorporated.

  12. Ice nucleation activity of polysaccharides

    Science.gov (United States)

    Bichler, Magdalena; Felgitsch, Laura; Haeusler, Thomas; Seidl-Seiboth, Verena; Grothe, Hinrich

    2015-04-01

    Heterogeneous ice nucleation is an important process in the atmosphere. It shows direct impact on our climate by triggering ice cloud formation and therefore it has much influence on the radiation balance of our planet (Lohmann et al. 2002; Mishchenko et al. 1996). The process itself is not completely understood so far and many questions remain open. Different substances have been found to exhibit ice nucleation activity (INA). Due to their vast differences in chemistry and morphology it is difficult to predict what substance will make good ice nuclei and which will not. Hence simple model substances must be found and be tested regarding INA. Our work aims at gaining to a deeper understanding of heterogeneous ice nucleation. We intend to find some reference standards with defined chemistry, which may explain the mechanisms of heterogeneous ice nucleation. A particular focus lies on biological carbohydrates in regards to their INA. Biological carbohydrates are widely distributed in all kingdoms of life. Mostly they are specific for certain organisms and have well defined purposes, e.g. structural polysaccharides like chitin (in fungi and insects) and pectin (in plants), which has also water-binding properties. Since they are widely distributed throughout our biosphere and mostly safe to use for nutrition purposes, they are well studied and easily accessible, rendering them ideal candidates as proxies. In our experiments we examined various carbohydrates, like the already mentioned chitin and pectin, as well as their chemical modifications. Lohmann U.; A Glaciation Indirect Aerosol Effect Caused by Soot Aerosols; J. Geoph. Res.; Vol. 24 No.4; pp 11-1 - 11-4; 2002 Mishchenko M.I., Rossow W.B., Macke A., Lacis A. A.; Sensitivity of Cirrus Cloud Albedo, Bidirectional Reflectance and Optical Thickness Retrieval Accuracy to Ice Particle Shape, J. Geoph. Res.; Vol. 101, No D12; pp. 16,973 - 16,985; 1996

  13. Revision of nucleated boiling mechanisms

    International Nuclear Information System (INIS)

    Converti, J.; Balino, J.L.

    1987-01-01

    The boiling occurrence plays an important role in the power reactors energy transfer. But still, there is not a final theory on the boiling mechanisms. This paper presents a critical analysis of the most important nucleated boiling models that appear in literature. The conflicting points are identified and experiments are proposed to clear them up. Some of these experiments have been performed at the Thermohydraulics laboratory (Bariloche Atomic Center). (Author)

  14. Mechanisms of nucleation in flashing flows

    International Nuclear Information System (INIS)

    Yan, F.; Giot, M.

    1989-01-01

    The mechanisms of nucleation have been analysed. Starting from the assumption that the activation of micro-cavities in the wall surfaces is the most probable nucleation mechanism in practical flashing system, the authors study in detail the nucleation in a micro-cavity. A three step nucleation criterion is proposed, namely: trapping cavity, activable cavity and active cavity. Then, a new nucleation model is presented. The output of the model is the prediction of the bubble departure frequency versus the thermodynamic state of the liquid and the geometry of the cavity. The model can also predict the nucleation site density if the nature of the wall and the surface roughness are know. The prediction have been successfully compared with some preliminary experimental results. By combining the present model with Jones'theory, the flashing inception is correctly predicted. The use of this nucleation model for the complete modelling of a flashing non-equilibrium flow is in progress

  15. Low-dose (10-Gy) total skin electron beam therapy for cutaneous T-cell lymphoma

    DEFF Research Database (Denmark)

    Kamstrup, Maria R; Gniadecki, Robert; Iversen, Lars

    2015-01-01

    a total dose of 10 Gy in 10 fractions. Data from 10 of these patients were published previously but were included in the current pooled data analysis. Outcome measures were response rate, duration of response, and toxicity. RESULTS: The overall response rate was 95% with a complete cutaneous response......PURPOSE: Cutaneous T-cell lymphomas (CTCLs) are dominated by mycosis fungoides (MF) and Sézary syndrome (SS), and durable disease control is a therapeutic challenge. Standard total skin electron beam therapy (TSEBT) is an effective skin-directed therapy, but the possibility of retreatments...... or a very good partial response rate (response was 174 days (5.8 months; range: 60-675 days). TSEBT-related acute adverse events (grade 1 or 2) were observed in 60% of patients. CONCLUSIONS...

  16. Loss of P53 Function in Colon Cancer Cells Results in Increased Phosphocholine and Total Choline

    Directory of Open Access Journals (Sweden)

    Noriko Mori

    2004-10-01

    Full Text Available Mutations in the p53 gene are the most frequently observed genetic lesions in human cancers. Human cancers that contain a p53 mutation are more aggressive, more apt to metastasize, and more often fatal. p53 controls numerous downstream targets that can influence various outcomes such as apoptosis, growth arrest, and DNA repair. Based on previous observations using 1H magnetic resonance spectroscopy (MRS, we have identified choline phospholipid metabolite intensities typical of increased malignancy. Here we have used 1H MRS to characterize the choline phospholipid metabolite levels of p53+/+ and p53−/– cells, and demonstrated that loss of p53 function results in increased phosphocholine and total choline. These data suggest that the increased malignancy of cancer cells resulting from loss of p53 may be mediated, in part, through the choline phospholipid pathway.

  17. Total glucosides of paeony inhibits Th1/Th17 cells via decreasing dendritic cells activation in rheumatoid arthritis.

    Science.gov (United States)

    Lin, Jinpiao; Xiao, Lianbo; Ouyang, Guilin; Shen, Yu; Huo, Rongfen; Zhou, Zhou; Sun, Yue; Zhu, Xianjin; Zhang, Jie; Shen, Baihua; Li, Ningli

    2012-12-01

    Total glucoside of paeony (TGP), an active compound extracted from paeony root, has been used in therapy for rheumatoid arthritis (RA). Th1 and Th17 cells are now believed to play crucial roles in the lesions of RA. However, the molecular mechanism of TGP in inhibition of Th1 and Th17 cells remains unclear. In this study, we found that TGP treatment significantly decreased percentage and number of Th1 and Th17 cells in collagen induced arthritis (CIA) mice. Consistently, treatment with TGP decreased expression of T-bet and RORγt as well as phosphorylation of STAT1 and STAT3. In particular, TGP treatment inhibited dendritic cells (DCs) maturation and reduced production of IL-12 and IL-6. Moreover, TGP-treatment RA patients showed shank population of matured DCs and IFN-γ-, IL-17-producing cells. Taken together, our results demonstrated that TGP inhibited maturation and activation of DCs, which led to impaired Th1 and Th17 differentiation in vivo. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Efficiency and Cost Analysis of Cell Saver Auto Transfusion System in Total Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Mustafa Gökhan Bilgili

    2014-06-01

    Full Text Available Background: Blood loss and replacement is still a controversial issue in major orthopaedic surgery. Allogenic blood transfusion may cause legal problems and concerns regarding the transmission of transfusion-related diseases. Cellsaver Systems (CSS were developed as an alternative to allogenic transfusion but CSS transfusion may cause coagulation, infection and haemodynamic instability. Aims: Our aim was to analyse the efficiency and cost analysis of a cell saver auto-transfusion system in the total knee arthroplasty procedure. Study Design: Retrospective comparative study. Methods: Those patients who were operated on by unilateral, cemented total knee arthroplasty (TKA were retrospectively evaluated. Group 1 included 37 patients who were treated using the cell saver system, and Group 2 involved 39 patients who were treated by allogenic blood transfusion. The groups were compared in terms of preoperative haemoglobin and haematocrit levels, blood loss and transfusion amount, whether allogenic transfusion was made, degree of deformity, body mass index and cost. Results: No significant results could be obtained in the statistical comparisons made in terms of the demographic properties, deformity properties, preoperative laboratory values, transfusion amount and length of hospital stay of the groups. Average blood loss was calculated to be less in Group 1 (p<0.05 and cost was higher in Group 1 (p<0.05. Conclusion: Cell saver systems do not decrease the amount of allogenic blood transfusion and costs more. Therefore, the routine usage of the auto-transfusion systems is a controversial issue. Cell saver system usage does not affect allogenic blood transfusion incidence or allogenic blood transfusion volume. It was found that preoperative haemoglobin and body mass index rates may affect allogenic blood transfusion. Therefore, it is foreseen that auto-transfusion systems could be useful in patients with low haemoglobin level and body mass index.

  19. Extramedullary Relapse Following Total Marrow and Lymphoid Irradiation in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Hyun [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States); Stein, Anthony [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States); Tsai, Nicole [Department of Biostatistics, City of Hope National Medical Center, Duarte, California (United States); Schultheiss, Timothy E. [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States); Palmer, Joycelynne [Department of Biostatistics, City of Hope National Medical Center, Duarte, California (United States); Liu, An [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States); Rosenthal, Joseph [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States); Department of Pediatrics, City of Hope National Medical Center, Duarte, California (United States); Forman, Stephen J. [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States); Wong, Jeffrey Y.C., E-mail: jwong@coh.org [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States)

    2014-05-01

    Purpose: Approximately 5% to 20% of patients who undergo total body irradiation (TBI) in preparation for hematopoietic cell transplantation (HCT) can develop extramedullary (EM) relapse. Whereas total marrow and lymphoid irradiation (TMLI) provides a more conformally targeted radiation therapy for patients, organ sparing has the potential to place the patient at a higher risk for EM relapse than TBI. This study evaluated EM relapse in patients treated with TMLI at our institution. Methods and Materials: Patients eligible for analysis had been enrolled in 1 of 3 prospective TMLI trials between 2006 and 2012. The TMLI targeted bones, major lymph node chains, liver, spleen, testes, and brain, using image-guided tomotherapy with total dose ranging from 12 to 15 Gy. Results: A total of 101 patients with a median age of 47 years were studied. The median follow-up was 12.8 months. Incidence of EM relapse and bone marrow (BM) relapse were 12.9% and 25.7%, respectively. Of the 13 patients who had EM relapse, 4 also had BM relapse, and 7 had EM disease prior to HCT. There were a total of 19 EM relapse sites as the site of initial recurrence: 11 soft tissue, 6 lymph node, 2 skin. Nine of these sites were within the target region and received ≥12 Gy. Ten initial EM relapse sites were outside of the target region: 5 sites received 10.1 to 11.4 Gy while 5 sites received <10 Gy. Pretransplantation EM was the only significant predictor of subsequent EM relapse. The cumulative incidence of EM relapse was 4% at 1 year and 11.4% at 2 years. Conclusions: EM relapse incidence was as frequent in regions receiving ≥10 Gy as those receiving <10 Gy. EM relapse rates following TMLI that included HCT regimens were comparable to published results with regimens including TBI and suggest that TMLI is not associated with an increased EM relapse risk.

  20. Extramedullary Relapse Following Total Marrow and Lymphoid Irradiation in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation

    International Nuclear Information System (INIS)

    Kim, Ji Hyun; Stein, Anthony; Tsai, Nicole; Schultheiss, Timothy E.; Palmer, Joycelynne; Liu, An; Rosenthal, Joseph; Forman, Stephen J.; Wong, Jeffrey Y.C.

    2014-01-01

    Purpose: Approximately 5% to 20% of patients who undergo total body irradiation (TBI) in preparation for hematopoietic cell transplantation (HCT) can develop extramedullary (EM) relapse. Whereas total marrow and lymphoid irradiation (TMLI) provides a more conformally targeted radiation therapy for patients, organ sparing has the potential to place the patient at a higher risk for EM relapse than TBI. This study evaluated EM relapse in patients treated with TMLI at our institution. Methods and Materials: Patients eligible for analysis had been enrolled in 1 of 3 prospective TMLI trials between 2006 and 2012. The TMLI targeted bones, major lymph node chains, liver, spleen, testes, and brain, using image-guided tomotherapy with total dose ranging from 12 to 15 Gy. Results: A total of 101 patients with a median age of 47 years were studied. The median follow-up was 12.8 months. Incidence of EM relapse and bone marrow (BM) relapse were 12.9% and 25.7%, respectively. Of the 13 patients who had EM relapse, 4 also had BM relapse, and 7 had EM disease prior to HCT. There were a total of 19 EM relapse sites as the site of initial recurrence: 11 soft tissue, 6 lymph node, 2 skin. Nine of these sites were within the target region and received ≥12 Gy. Ten initial EM relapse sites were outside of the target region: 5 sites received 10.1 to 11.4 Gy while 5 sites received <10 Gy. Pretransplantation EM was the only significant predictor of subsequent EM relapse. The cumulative incidence of EM relapse was 4% at 1 year and 11.4% at 2 years. Conclusions: EM relapse incidence was as frequent in regions receiving ≥10 Gy as those receiving <10 Gy. EM relapse rates following TMLI that included HCT regimens were comparable to published results with regimens including TBI and suggest that TMLI is not associated with an increased EM relapse risk

  1. Thermodynamic and Dynamic Aspects of Ice Nucleation

    Science.gov (United States)

    Barahona, Donifan

    2018-01-01

    It is known that ice nucleating particles (INP) immersed within supercooled droplets promote the formation of ice. Common theoretical models used to represent this process assume that the immersed particle lowers the work of ice nucleation without significantly affecting the dynamics of water in the vicinity of the particle. This is contrary to evidence showing that immersed surfaces significantly affect the viscosity and diffusivity of vicinal water. To study how this may affect ice formation this work introduces a model linking the ice nucleation rate to the modification of the dynamics and thermodynamics of vicinal water by immersed particles. It is shown that INP that significantly reduce the work of ice nucleation also pose strong limitations to the growth of the nascent ice germs. This leads to the onset of a new ice nucleation regime, called spinodal ice nucleation, where the dynamics of ice germ growth instead of the ice germ size determines the nucleation rate. Nucleation in this regime is characterized by an enhanced sensitivity to particle area and cooling rate. Comparison of the predicted ice nucleation rate against experimental measurements for a diverse set of species relevant to cloud formation suggests that spinodal ice nucleation may be common in nature.

  2. Efficiency and cost analysis of cell saver auto transfusion system in total knee arthroplasty.

    Science.gov (United States)

    Bilgili, Mustafa Gökhan; Erçin, Ersin; Peker, Gökhan; Kural, Cemal; Başaran, Serdar Hakan; Duramaz, Altuğ; Avkan, Cevdet

    2014-06-01

    Blood loss and replacement is still a controversial issue in major orthopaedic surgery. Allogenic blood transfusion may cause legal problems and concerns regarding the transmission of transfusion-related diseases. Cellsaver Systems (CSS) were developed as an alternative to allogenic transfusion but CSS transfusion may cause coagulation, infection and haemodynamic instability. Our aim was to analyse the efficiency and cost analysis of a cell saver auto-transfusion system in the total knee arthroplasty procedure. Retrospective comparative study. Those patients who were operated on by unilateral, cemented total knee arthroplasty (TKA) were retrospectively evaluated. Group 1 included 37 patients who were treated using the cell saver system, and Group 2 involved 39 patients who were treated by allogenic blood transfusion. The groups were compared in terms of preoperative haemoglobin and haematocrit levels, blood loss and transfusion amount, whether allogenic transfusion was made, degree of deformity, body mass index and cost. No significant results could be obtained in the statistical comparisons made in terms of the demographic properties, deformity properties, preoperative laboratory values, transfusion amount and length of hospital stay of the groups. Average blood loss was calculated to be less in Group 1 (pblood transfusion and costs more. Therefore, the routine usage of the auto-transfusion systems is a controversial issue. Cell saver system usage does not affect allogenic blood transfusion incidence or allogenic blood transfusion volume. It was found that preoperative haemoglobin and body mass index rates may affect allogenic blood transfusion. Therefore, it is foreseen that auto-transfusion systems could be useful in patients with low haemoglobin level and body mass index.

  3. White Blood Cell Count and Total and Cause-Specific Mortality in the Women's Health Initiative.

    Science.gov (United States)

    Kabat, Geoffrey C; Kim, Mimi Y; Manson, JoAnn E; Lessin, Lawrence; Lin, Juan; Wassertheil-Smoller, Sylvia; Rohan, Thomas E

    2017-07-01

    White blood cell (WBC) count appears to predict total mortality and coronary heart disease (CHD) mortality, but it is unclear to what extent the association reflects confounding by smoking, underlying illness, or comorbid conditions. We used data from the Women's Health Initiative to examine the associations of WBC count with total mortality, CHD mortality, and cancer mortality. WBC count was measured at baseline in 160,117 postmenopausal women and again in year 3 in 74,375 participants. Participants were followed for a mean of 16 years. Cox proportional hazards models were used to estimate the relative mortality hazards associated with deciles of baseline WBC count and of the mean of baseline + year 3 WBC count. High deciles of both baseline and mean WBC count were positively associated with total mortality and CHD mortality, whereas the association with cancer mortality was weaker. The association of WBC count with mortality was independent of smoking and did not appear to be influenced by previous disease history. The potential clinical utility of this common laboratory test in predicting mortality risk warrants further study. © The Author 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Differential effect of L3T4+ cells on recovery from total-body irradiation

    International Nuclear Information System (INIS)

    Pantel, K.; Nakeff, A.

    1990-01-01

    We have examined the importance of L3T4+ (murine equivalent to CD4+) cells for hematopoietic regulation in vivo in unperturbed mice and mice recovering from total-body irradiation (TBI) using a cytotoxic monoclonal antibody (MoAb) raised with the GK 1.5 hybridoma. Ablating L3T4+ cells in normal (unperturbed) B6D2F1 mice substantially decreased the S-phase fraction (determined by in vivo hydroxyurea suicide) of erythroid progenitor cells (erythroid colony-forming units, CFU-E) as compared to the pretreatment level (10% +/- 14.1% [day 3 following depletion] vs 79.8% +/- 15.9%, respectively) with a corresponding decrease in the marrow content of CFU-E at this time to approximately 1% of the pretreatment value. Although the S-phase fraction of CFU-GM was decreased to 2.2% +/- 3.1% 3 days after L3T4+ cell ablation from the 21.3% +/- 8.3% pretreatment value, CFU-GM cellularity showed little change over the 3 days following anti-L3T4 treatment. Anti-L3T4 MoAb treatment had little or no effect on either the S-phase fraction or the marrow content of hematopoietic stem cells (spleen colony-forming units, CFU-S) committed to myeloerythroid differentiation. Ablating L3T4+ cells prior to a single dose of 2 Gy TBI resulted in significantly reduced marrow contents of CFU-S on day 3 and granulocyte-macrophage colony-forming units (CFU-GM) on day 6 following TBI, with little or no effect on the corresponding recovery of CFU-E. The present findings provide the first in vivo evidence that L3T4+ cells are involved in: (1) maintaining the proliferative activity of CFU-E and CFU-GM in unperturbed mice and (2) supporting the restoration of CFU-S and CFU-GM following TBI-induced myelosuppression

  5. Effects of streptomycin, desiccation, and UV radiation on ice nucleation by Pseudomonas viridiflava

    International Nuclear Information System (INIS)

    Anderson, J.A.; Ashworth, E.N.

    1986-01-01

    Streptomycin (100 micrograms per milliliter), desiccation (over CaSO 4 ), and ultraviolet radiation (4500 microwatts per square centimeter at 254 nonometers for 15 minutes) reduced ice nucleation activity by Pseudomonas viridiflava strain W-1 as determined by freezing drops of the bacterial suspensions. Highest residual ice nucleation activity by dead cells was obtained by desiccation, although no freezing above -3.5 0 C was detected. The rate and extent of loss of ice nucleation activity following streptomycin and ultraviolet treatment was affected by preconditioning temperature. At 21 0 C and above, loss of activity by dead cells was rapid and irreversible

  6. Influence of hyperoxia on the number of nucleated cells and oxygen tension in rat bone marrow after whole-body irradiation

    International Nuclear Information System (INIS)

    Zima, M.; Vodicka, I.

    1987-01-01

    The cell number in the femur bone marrow of rats determined three days after X-ray or gamma irradiation is inversely proportional to the dose while oxygen tension in the marrow shows direct dependence on the dose. With fractionation of the lethal dose of gamma radiation (9 Gy) into two doses with different time intervals between them, a greater number of bone marrow cells and a smaller oxygen tension are reached on the 3rd day after the second dose, reflecting the extent of bone marrow repair. A short-term hyperoxia (95% O 2 + 5% CO 2 ) lasting 20 min from the end of exposure compared with the euoxic conditions induced, on the 3rd day after the second fraction, a nonsignificant but reproducible increase in the marrow cell number and a decrease in partial oxygen tension in the distal part of femur marrow. The results obtained testify that immediate short-term hyperoxia facilitates regeneration of the marrow and that a greater number of cells accompanied by greater metabolic activity and oxygen consumption decrease the partial oxygen tension measured on the 3rd day following the last exposure. (author). 7 figs., 16 refs

  7. Survival and ice nucleation activity of bacteria as aerosols in a cloud simulation chamber

    Science.gov (United States)

    Amato, P.; Joly, M.; Schaupp, C.; Attard, E.; Möhler, O.; Morris, C. E.; Brunet, Y.; Delort, A.-M.

    2015-06-01

    The residence time of bacterial cells in the atmosphere is predictable by numerical models. However, estimations of their aerial dispersion as living entities are limited by a lack of information concerning survival rates and behavior in relation to atmospheric water. Here we investigate the viability and ice nucleation (IN) activity of typical atmospheric ice nucleation active bacteria (Pseudomonas syringae and P. fluorescens) when airborne in a cloud simulation chamber (AIDA, Karlsruhe, Germany). Cell suspensions were sprayed into the chamber and aerosol samples were collected by impingement at designated times over a total duration of up to 18 h, and at some occasions after dissipation of a cloud formed by depressurization. Aerosol concentration was monitored simultaneously by online instruments. The cultivability of airborne cells decreased exponentially over time with a half-life time of 250 ± 30 min (about 3.5 to 4.5 h). In contrast, IN activity remained unchanged for several hours after aerosolization, demonstrating that IN activity was maintained after cell death. Interestingly, the relative abundance of IN active cells still airborne in the chamber was strongly decreased after cloud formation and dissipation. This illustrates the preferential precipitation of IN active cells by wet processes. Our results indicate that from 106 cells aerosolized from a surface, one would survive the average duration of its atmospheric journey estimated at 3.4 days. Statistically, this corresponds to the emission of 1 cell that achieves dissemination every ~ 33 min m-2 of cultivated crops fields, a strong source of airborne bacteria. Based on the observed survival rates, depending on wind speed, the trajectory endpoint could be situated several hundreds to thousands of kilometers from the emission source. These results should improve the representation of the aerial dissemination of bacteria in numeric models.

  8. Nucleation and growth of cadherin adhesions

    International Nuclear Information System (INIS)

    Lambert, Mireille; Thoumine, Olivier; Brevier, Julien; Choquet, Daniel; Riveline, Daniel; Mege, Rene-Marc

    2007-01-01

    Cell-cell contact formation relies on the recruitment of cadherin molecules and their anchoring to actin. However, the precise chronology of events from initial cadherin trans-interactions to adhesion strengthening is unclear, in part due to the lack of access to the distribution of cadherins within adhesion zones. Using N-cadherin expressing cells interacting with N-cadherin coated surfaces, we characterized the formation of cadherin adhesions at the ventral cell surface. TIRF and RIC microscopies revealed streak-like accumulations of cadherin along actin fibers. FRAP analysis indicated that engaged cadherins display a slow turnover at equilibrium, compatible with a continuous addition and removal of cadherin molecules within the adhesive contact. Association of cadherin cytoplasmic tail to actin as well as actin cables and myosin II activity are required for the formation and maintenance of cadherin adhesions. Using time lapse microscopy we deciphered how cadherin adhesions form and grow. As lamellipodia protrude, cadherin foci stochastically formed a few microns away from the cell margin. Neo-formed foci coalesced aligned and coalesced with preformed foci either by rearward sliding or gap filling to form cadherin adhesions. Foci experienced collapse at the rear of cadherin adhesions. Based on these results, we present a model for the nucleation, directional growth and shrinkage of cadherin adhesions

  9. Total intermittent Pringle maneuver during liver resection can induce intestinal epithelial cell damage and endotoxemia.

    Directory of Open Access Journals (Sweden)

    Simon A W G Dello

    Full Text Available OBJECTIVES: The intermittent Pringle maneuver (IPM is frequently applied to minimize blood loss during liver transection. Clamping the hepatoduodenal ligament blocks the hepatic inflow, which leads to a non circulating (hepatosplanchnic outflow. Also, IPM blocks the mesenteric venous drainage (as well as the splenic drainage with raising pressure in the microvascular network of the intestinal structures. It is unknown whether the IPM is harmful to the gut. The aim was to investigate intestinal epithelial cell damage reflected by circulating intestinal fatty acid binding protein levels (I-FABP in patients undergoing liver resection with IPM. METHODS: Patients who underwent liver surgery received total IPM (total-IPM or selective IPM (sel-IPM. A selective IPM was performed by selectively clamping the right portal pedicle. Patients without IPM served as controls (no-IPM. Arterial blood samples were taken immediately after incision, ischemia and reperfusion of the liver, transection, 8 hours after start of surgery and on the first post-operative day. RESULTS: 24 patients (13 males were included. 7 patients received cycles of 15 minutes and 5 patients received cycles of 30 minutes of hepatic inflow occlusion. 6 patients received cycles of 15 minutes selective hepatic occlusion and 6 patients underwent surgery without inflow occlusion. Application of total-IPM resulted in a significant increase in I-FABP 8 hours after start of surgery compared to baseline (p<0.005. In the no-IPM group and sel-IPM group no significant increase in I-FABP at any time point compared to baseline was observed. CONCLUSION: Total-IPM in patients undergoing liver resection is associated with a substantial increase in arterial I-FABP, pointing to intestinal epithelial injury during liver surgery. TRIAL REGISTRATION: ClinicalTrials.gov NCT01099475.

  10. Heterogeneous Nucleation and Growth of Nanoparticles at Environmental Interfaces.

    Science.gov (United States)

    Jun, Young-Shin; Kim, Doyoon; Neil, Chelsea W

    2016-09-20

    water chemistry and substrate identity on heterogeneously and homogeneously formed nanoscale precipitate size dimensions and total particle volume. Using this technique, we also provided a new platform for quantitatively comparing between heterogeneous and homogeneous nucleation and growth of nanoparticles and obtaining undiscovered interfacial energies between nuclei and surfaces. In addition, nanoscale surface characterization tools, such as in situ atomic force microscopy (AFM), were utilized to support and complement our findings. With these powerful nanoscale tools, we systematically evaluated the influences of environmentally abundant (oxy)anions and cations and the properties of environmental surfaces, such as surface charge and hydrophobicity. The findings, significantly enhanced by in situ observations, can lead to a more accurate prediction of the behaviors of nanoparticles in the environment and enable better control of the physicochemical properties of nanoparticles in engineered systems, such as catalytic reactions and energy storage.

  11. Nucleation in an ultra low ionization environment

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean

    Atmospheric ions can enhance the nucleation of aerosols, as has been established by experiments, observation, and theory. In the clean marine atmosphere ionization is mainly caused by cosmic rays which in turn are controlled by the activity of the Sun, thus providing a potential link between solar...... activity and climate. In order to understand the effect ions may have on the production of cloud condensation nuclei the overall contribution of ion induced nucleation to the global production of secondary aerosols must be determined. One issue with determining this contribution is that several mechanisms...... for nucleation exist and it can be difficult to determine the relative importance of the various mechanisms in a given nucleation event when both ion induced and electrically neutral nucleation mechanisms are at work at the same time. We have carried out nucleation experiments in the Boulby Underground...

  12. Sulfur driven nucleation mode formation in diesel exhaust under transient driving conditions.

    Science.gov (United States)

    Karjalainen, Panu; Rönkkö, Topi; Pirjola, Liisa; Heikkilä, Juha; Happonen, Matti; Arnold, Frank; Rothe, Dieter; Bielaczyc, Piotr; Keskinen, Jorma

    2014-02-18

    Sulfur driven diesel exhaust nucleation particle formation processes were studied in an aerosol laboratory, on engine dynamometers, and on the road. All test engines were equipped with a combination of a diesel oxidation catalyst (DOC) and a partial diesel particulate filter (pDPF). At steady operating conditions, the formation of semivolatile nucleation particles directly depended on SO2 conversion in the catalyst. The nucleation particle emission was most significant after a rapid increase in engine load and exhaust gas temperature. Results indicate that the nucleation particle formation at transient driving conditions does not require compounds such as hydrocarbons or sulfated hydrocarbons, however, it cannot be explained only by the nucleation of sulfuric acid. A real-world exhaust study with a heavy duty diesel truck showed that the nucleation particle formation occurs even with ultralow sulfur diesel fuel, even at downhill driving conditions, and that nucleation particles can contribute 60% of total particle number emissions. In general, due to sulfur storage and release within the exhaust aftertreatment systems and transients in driving, emissions of nucleation particles can even be the dominant part of modern diesel vehicle exhaust particulate number emissions.

  13. XRD total scattering of the CZTS nanoparticle absorber layer for the thin film solar cells

    DEFF Research Database (Denmark)

    Symonowicz, Joanna; Jensen, Kirsten M. Ø.; Engberg, Sara Lena Josefin

    Cu2ZnSnS4 (CZTS) thin film solar cells are cheap, non-toxic and present an efficiency up to 9,2% [1]. They can be easily manufactured by the deposition of the nanoparticle ink as a thin film followed by a thermal treatment to obtain large grains [2]. Therefore, CZTS has the potential...... to revolutionize the solar energy market. However, to commercialize CZTS nanoparticle thin films, the efficiency issues must yet be resolved. In order to do so, it is vital to understand in detail their nanoscale atomic structure. CZTS crystallize in the kesterite structure, where Cu and Zn is distributed between......-ray Diffraction data with X-ray total scattering with Pair Distribution Function analysis. Powder neutron diffraction will furthermore allow characterization of the cation disorder on the metal sites in the kesterite structure. The nanoparticle ink is also characterized by XRD, EDS, and Raman spectroscopy...

  14. Truncated Dual-Cap Nucleation Site Development

    Science.gov (United States)

    Matson, Douglas M.; Sander, Paul J.

    2012-01-01

    During heterogeneous nucleation within a metastable mushy-zone, several geometries for nucleation site development must be considered. Traditional spherical dual cap and crevice models are compared to a truncated dual cap to determine the activation energy and critical cluster growth kinetics in ternary Fe-Cr-Ni steel alloys. Results of activation energy results indicate that nucleation is more probable at grain boundaries within the solid than at the solid-liquid interface.

  15. Effects of clustered nucleation on recrystallization

    DEFF Research Database (Denmark)

    Storm, Søren; Juul Jensen, Dorte

    2009-01-01

    Computer simulations are used to study effects of an experimentally determined 3D distribution of nucleation sites on the recrystallization kinetics and on the evolution of the recrystallized microstructure as compared to simulations with random nucleation. It is found that although...... the experimentally observed clustering is not very strong, it changes the kinetics and the recrystallized microstructural morphology plus leads to a recrystallized grain size distribution, which is significantly broadened compared to that of random nucleation simulations. (C) 2009 Published by Elsevier Ltd...

  16. Ice nucleation triggered by negative pressure.

    Science.gov (United States)

    Marcolli, Claudia

    2017-11-30

    Homogeneous ice nucleation needs supercooling of more than 35 K to become effective. When pressure is applied to water, the melting and the freezing points both decrease. Conversely, melting and freezing temperatures increase under negative pressure, i.e. when water is stretched. This study presents an extrapolation of homogeneous ice nucleation temperatures from positive to negative pressures as a basis for further exploration of ice nucleation under negative pressure. It predicts that increasing negative pressure at temperatures below about 262 K eventually results in homogeneous ice nucleation while at warmer temperature homogeneous cavitation, i. e. bubble nucleation, dominates. Negative pressure occurs locally and briefly when water is stretched due to mechanical shock, sonic waves, or fragmentation. The occurrence of such transient negative pressure should suffice to trigger homogeneous ice nucleation at large supercooling in the absence of ice-nucleating surfaces. In addition, negative pressure can act together with ice-inducing surfaces to enhance their intrinsic ice nucleation efficiency. Dynamic ice nucleation can be used to improve properties and uniformity of frozen products by applying ultrasonic fields and might also be relevant for the freezing of large drops in rainclouds.

  17. Probabilistic approach to lysozyme crystal nucleation kinetics.

    Science.gov (United States)

    Dimitrov, Ivaylo L; Hodzhaoglu, Feyzim V; Koleva, Dobryana P

    2015-09-01

    Nucleation of lysozyme crystals in quiescent solutions at a regime of progressive nucleation is investigated under an optical microscope at conditions of constant supersaturation. A method based on the stochastic nature of crystal nucleation and using discrete time sampling of small solution volumes for the presence or absence of detectable crystals is developed. It allows probabilities for crystal detection to be experimentally estimated. One hundred single samplings were used for each probability determination for 18 time intervals and six lysozyme concentrations. Fitting of a particular probability function to experimentally obtained data made possible the direct evaluation of stationary rates for lysozyme crystal nucleation, the time for growth of supernuclei to a detectable size and probability distribution of nucleation times. Obtained stationary nucleation rates were then used for the calculation of other nucleation parameters, such as the kinetic nucleation factor, nucleus size, work for nucleus formation and effective specific surface energy of the nucleus. The experimental method itself is simple and adaptable and can be used for crystal nucleation studies of arbitrary soluble substances with known solubility at particular solution conditions.

  18. Biologically effective dose in total-body irradiation and hematopoietic stem cell transplantation

    International Nuclear Information System (INIS)

    Kal, H.B.; Kempen-Harteveld, M.L. van; Heijenbrok-Kal, M.H.; Struikmans, H.

    2006-01-01

    Background and Purpose: Total-body irradiation (TBI) is an important part of the conditioning regimen for hematopoietic stem cell transplantation (HSCT) in patients with hematologic malignancies. The results after treatment with various TBI regimes were compared, and dose-effect relationships for the endpoints relapse incidence, disease-free survival, treatment-related mortality, and overall survival were derived. The aim was to define requirements for an optimal treatment schedule with respect to leukemic cell kill and late normal-tissue morbidity. Material and Methods: A literature search was performed. Three randomized studies, four studies comparing results of two or three TBI regimens, and nine reports with results of one specific TBI regimen were identified. Biologically effective doses (BEDs) were calculated. The results of the randomized studies and the studies comparing results of two or three TBI regimens were pooled, and the pooled relative risk (RR) was calculated for the treatments with high BED values versus treatments with a low BED. BED-effect relationships were obtained. Results: RRs for the high BED treatments were significantly lower for relapse incidence, not significantly different for disease-free survival and treatment-related mortality, and significantly higher for overall survival. BED-effect relationships indicate a decrease in relapse incidence and treatment-related mortality and an increase in disease-free and overall survival with higher BED values. Conclusion: 'More dose is better', provided that a TBI setting is used limiting the BEDs of lungs, kidneys, and eye lenses. (orig.)

  19. Total lymphoid irradiation based conditioning for hematopoietic stem cell transplantation in severe aplastic anemia

    International Nuclear Information System (INIS)

    Lee, Yun Hee; Kim, Ji Yoon; Choi, Byung Ock; Ryu, Mi Ryeong; Chung, Su Mi

    2012-01-01

    To retrospectively evaluate the outcome and toxicity of total lymphoid irradiation (TLI) based conditioning regimen for allogeneic hematopoietic stem cell transplantation (HSCT) in severe aplastic anemia (SAA) patients who experienced an engraftment failure from prior HSCT or were heavily transfused. Between 1995 and 2006, 20 SAA patients received TLI for conditioning of HSCT. All patients were multi-transfused or had long duration of disease. Fifteen (75%) patients had graft failure from prior HSCT. In 18 (90%) patients, the donors were human leukocyte antigen identical siblings. The stem cell source was the peripheral blood stem cell in 15 (75%) patients. The conditioning regimen was composed of antithymocyte globulin plus TLI with a median dose of 750 cGy in 1 fraction. The graft-versus-host disease (GVHD) prophylaxis used cyclosporine with methotrexate. With a median follow-up of 10.8 years, graft failures developed in 6 patients. Among them, 3 patients received their third HSCT to be engrafted finally. The Kaplan-Meier overall survival rate was 85.0% and 83.1% at 5 and 10 years, respectively. The incidence of acute and chronic GVHD was 20% and 20%, respectively. None of the patients have developed a malignancy after HSCT. In our study, TLI based conditioning in allogeneic HSCT was feasible with acceptable rates of GVHD in SAA patients who experienced graft failure from prior HSCT or was at a high risk of graft rejection. We achieved relatively better results of engraftment and survival with a long term follow-up.

  20. Total lymphoid irradiation based conditioning for hematopoietic stem cell transplantation in severe aplastic anemia

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yun Hee; Kim, Ji Yoon; Choi, Byung Ock; Ryu, Mi Ryeong; Chung, Su Mi [Dept. of Radiation Oncology, The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of)

    2012-12-15

    To retrospectively evaluate the outcome and toxicity of total lymphoid irradiation (TLI) based conditioning regimen for allogeneic hematopoietic stem cell transplantation (HSCT) in severe aplastic anemia (SAA) patients who experienced an engraftment failure from prior HSCT or were heavily transfused. Between 1995 and 2006, 20 SAA patients received TLI for conditioning of HSCT. All patients were multi-transfused or had long duration of disease. Fifteen (75%) patients had graft failure from prior HSCT. In 18 (90%) patients, the donors were human leukocyte antigen identical siblings. The stem cell source was the peripheral blood stem cell in 15 (75%) patients. The conditioning regimen was composed of antithymocyte globulin plus TLI with a median dose of 750 cGy in 1 fraction. The graft-versus-host disease (GVHD) prophylaxis used cyclosporine with methotrexate. With a median follow-up of 10.8 years, graft failures developed in 6 patients. Among them, 3 patients received their third HSCT to be engrafted finally. The Kaplan-Meier overall survival rate was 85.0% and 83.1% at 5 and 10 years, respectively. The incidence of acute and chronic GVHD was 20% and 20%, respectively. None of the patients have developed a malignancy after HSCT. In our study, TLI based conditioning in allogeneic HSCT was feasible with acceptable rates of GVHD in SAA patients who experienced graft failure from prior HSCT or was at a high risk of graft rejection. We achieved relatively better results of engraftment and survival with a long term follow-up.

  1. XMAP215 is a microtubule nucleation factor that functions synergistically with the γ-tubulin ring complex.

    Science.gov (United States)

    Thawani, Akanksha; Kadzik, Rachel S; Petry, Sabine

    2018-05-01

    How microtubules (MTs) are generated in the cell is a major question in understanding how the cytoskeleton is assembled. For several decades, γ-tubulin has been accepted as the universal MT nucleator of the cell. Although there is evidence that γ-tubulin complexes are not the sole MT nucleators, identification of other nucleation factors has proven difficult. Here, we report that the well-characterized MT polymerase XMAP215 (chTOG/Msps/Stu2p/Alp14/Dis1 homologue) is essential for MT nucleation in Xenopus egg extracts. The concentration of XMAP215 determines the extent of MT nucleation. Even though XMAP215 and the γ-tubulin ring complex (γ-TuRC) possess minimal nucleation activity individually, together, these factors synergistically stimulate MT nucleation in vitro. The amino-terminal TOG domains 1-5 of XMAP215 bind to αβ-tubulin and promote MT polymerization, whereas the conserved carboxy terminus is required for efficient MT nucleation and directly binds to γ-tubulin. In summary, XMAP215 and γ-TuRC together function as the principal nucleation module that generates MTs in cells.

  2. Void nucleation at elevated temperatures under cascade-damage irradiation

    International Nuclear Information System (INIS)

    Semenov, A.A.; Woo, C.H.

    2002-01-01

    The effects on void nucleation of fluctuations respectively due to the randomness of point-defect migratory jumps, the random generation of free point defects in discrete packages, and the fluctuating rate of vacancy emission from voids are considered. It was found that effects of the cascade-induced fluctuations are significant only at sufficiently high total sink strength. At lower sink strengths and elevated temperatures, the fluctuation in the rate of vacancy emission is the dominant factor. Application of the present theory to the void nucleation in annealed pure copper neutron-irradiated at elevated temperatures with doses of 10 -4 -10 -2 NRT dpa showed reasonable agreement between theory and experiment. This application also predicts correctly the temporal development of large-scale spatial heterogeneous microstructure during the void nucleation stage. Comparison between calculated and experimental void nucleation rates in neutron-irradiated molybdenum at temperatures where vacancy emission from voids is negligible showed reasonable agreement as well. It was clearly demonstrated that the athermal shrinkage of relatively large voids experimentally observable in molybdenum at such temperatures may be easily explained in the framework of the present theory

  3. Conjunctival-limbal autograft in total unilateral limbal stem cell deficiency

    Directory of Open Access Journals (Sweden)

    Petra Schollmayer

    2017-09-01

    Full Text Available Background: Corneal epithelium is renewed by stem cells (SC that reside at the corneal limbus. Reduced number of SC or their abnormal function lead to the ocular surface disease called limbal stem cell deficiency (LSCD, characterized by corneal conjunctivalization, vascularization, persistent epithelial defects, chronic inflammation, and loss of vision. In a case of total unilateral LSCD, autologous transplantation of limbal epithelial stem cells (LESC from the healthy eye is needed. We describe the surgical technique of choice for autologous limbal transplantation, called conjunctival limbal autograft (CLAU that we combined with amniotic membrane (AM use. We present the results of CLAU in three patients with total unilateral LSCD due to chemical injury.Methods: Autologous limbal transplantation CLAU begins with the removal of fibrovascular pannus from the diseased corneal surface and the harvesting of two conjunctival-limbal grafts from the healthy eye. The grafts are then transplanted on to the limbal area of the recipient eye. AM is used as a patch to cover the denuded cornea and limbal grafts, as well as a barrier preventing the conjunctival epithelium from encroaching on to the temporal and nasal side of the corneal surface. In the donor eye, AM is used to cover the donor sites. CLAU with the use of AM was performed in 3 patients with unilateral LSCD due to chemical eye injury. In one patient limbal transplantation was combined with symblepharon lysis for entropium repair. In all cases AM was removed 3–6 days postoperatively to assess the growth of new epithelium from the limbal grafts. In all patients the ocular surface was covered with another AM until the cornea was completely epithelized and the new epithelium stable. In one patient the corneal regrafting and cataract removal was performed subsequently.Results: CLAU was successful in 2 patients and partially successful in 1 patient during the follow up. In all cases the growth of new

  4. Structuring effects in binary nucleation : Molecular dynamics simulatons and coarse-grained nucleation theory

    NARCIS (Netherlands)

    Braun, S.; Kraska, T.; Kalikmanov, V.I.

    2013-01-01

    Binary clusters formed by vapor-liquid nucleation are frequently nonhomogeneous objects in which components are not well mixed. The structure of a cluster plays an important role in nucleation and cluster growth. We demonstrate structuring effects by studying high-pressure nucleation and cluster

  5. New trends in the nucleation research

    Science.gov (United States)

    Anisimov, M. P.; Hopke, P. K.

    2017-09-01

    During the last half of century the most of efforts have been directed towards small molecule system modeling using intermolecular potentials. Summarizing the nucleation theory, it can be concluded that the nowadays theory is far from complete. The vapor-gas nucleation theory can produce values that deviate from the experimental results by several orders of magnitude currently. Experiments on the vapor-gas nucleation rate measurements using different devices show significant inconsistencies in the measured rates as well. Theoretical results generally are quite reasonable for sufficiently low vapor nucleation rates where the capillary approximation is applicable. In the present research the advantages and current problems of the vapor-gas nucleation experiments are discussed briefly and a view of the future studies is presented. Using the brake points of the first derivative for the nucleation rate surface as markers of the critical embryos phase change is fresh idea to show the gas-pressure effect for the nucleating vapor-gas systems. To test the accuracy of experimental techniques, it is important to have a standard system that can be measured over a range of nucleation conditions. Several results illustrate that high-pressure techniques are needed to study multi-channel nucleation. In practical applications, parametric theories can be used for the systems of interest. However, experimental measurements are still the best source of information on nucleation rates. Experiments are labor intensive and costly, and thus, it is useful to extend the value of limited experimental measurements to a broader range of nucleation conditions. Only limited experimental data one needs for use in normalizing the slopes of the linearized nucleation rate surfaces. The nucleation rate surface is described in terms of steady-state nucleation rates. It is supposed that several new measuring systems, such as High Pressure Flow Diffusion Chamber for pressure limit up to 150 bar will be

  6. Surgical outcomes after total pancreatectomy and islet cell autotransplantation in pediatric patients.

    Science.gov (United States)

    Wilson, Gregory C; Sutton, Jeffrey M; Salehi, Marzieh; Schmulewitz, Nathan; Smith, Milton T; Kucera, Stephen; Choe, Kyuran A; Brunner, John E; Abbott, Daniel E; Sussman, Jeffrey J; Ahmad, Syed A

    2013-10-01

    This study aims to review surgical outcomes of pediatric patients undergoing total pancreatectomy with islet cell autotransplantation (TP/IAT) for the treatment of chronic pancreatitis (CP). All pediatric patients (≤18 years old) undergoing TP/IAT over a 10-year period (December 2002-June 2012) were identified for inclusion in a single-center, observational cohort study. Retrospective chart review was performed to identify pertinent preoperative, perioperative, and postoperative data, including narcotic usage, insulin requirements, etiology of pancreatitis, previous operative interventions, operative times, islet cell yields, duration of hospital stay, and overall quality of life. Quality of life was assessed using the Short Form-36 health questionnaire. Fourteen pediatric patients underwent TP/IAT for the treatment of CP at the University of Cincinnati with a mean age of 15.9 years (range, 14-18) and a mean body mass index of 21.8 kg/m(2) (range, 14-37). Of the patients, 50% (n = 7) were male and 29% had undergone previous pancreatic operations (1 each of Whipple, Puestow, Frey, and Berne procedures). Etiology of pancreatitis was idiopathic for 57% (n = 8); the remainder had identified genetic mutations predisposing to pancreatitis (CFTR, n = 4; SPINK1, n = 1; PRSS1, n = 1). Mean operative time was 532 minutes (range, 360-674) with an average hospital duration of stay of 16 days (range, 7-37). Islet cell isolation resulted in mean islet cell equivalents (IEQ) of 500,443 in patients without previous pancreatic surgery versus 413,671 IEQ in patients with prior pancreatic surgery (P = .12). Median patient follow-up was 9 months from surgery (range, 1-78). Preoperatively, patients required on average 32.7 morphine equivalent mg per day (MEQ), which improved to 13.9 MEQ at most recent follow-up. Eleven patients (79%) were narcotic independent. None of the patients were diabetic preoperatively. All of the patients were discharged after the operation with scheduled

  7. Analytical description of brittle-to-ductile transition in bcc metals. Nucleation of dislocation loop at the crack tip

    International Nuclear Information System (INIS)

    Voskoboinikov, R.E.

    2002-03-01

    Nucleation of dislocation loop at the crack tip in a material subjected to uniaxial loading is investigated. Analytical expression for the total energy of rectangular dislocation loop at the crack tip is found. Dependence of the nucleation energy barrier on dislocation loop shape and stress intensity factor at the crack tip is determined. It is established that the energetic barrier for nucleation of dislocation loop strongly depends on the stress intensity factor. Nucleation of dislocation loop is very sensitive to stress field modifiers (forest dislocations, precipitates, clusters of point defects, etc) in the crack tip vicinity. (orig.)

  8. Transplantation of islet cells across major histocompatibility barriers after total lymphoid irradiation and infusion of allogeneic bone marrow cells

    International Nuclear Information System (INIS)

    Britt, L.D.; Scharp, D.W.; Lacy, P.E.; Slavin, S.

    1982-01-01

    Diabetic Lewis rats (AgB1/L) were evaluated as recipients of allogeneic Wistar-Furth (AgB2/2) isolated adult islets without the use of standard recipient immunosuppression. One group was treated with fractionated total lymphoid irradiation (TLI) and Wistar-Furth bone marrow cell reconstitution to proven chimerism prior to islet transplantation. This group returned to a prediabetic state following Wistar-Furth islet transplantation without any evidence of rejection for 100 days posttransplant. A second group of Lewis rats received only TLI without bone marrow treatment. They gave a varying result following islet transplantation with one recipient showing evidence of prolonged islet survival. A third chimeric control group did not receive isolated islets and did not alter their diabetic state. A fourth group was not given TLI nor donor bone marrow cells and uniformly rejected their allogeneic islets by 7 days. Thus, allogeneic adult islets will survive across major rat histocompatibility barriers using TLI and donor bone marrow chimerism as the only form of immunosuppression

  9. Urediospores of rust fungi are ice nucleation active at > -10 °C and harbor ice nucleation active bacteria

    Science.gov (United States)

    Morris, C. E.; Sands, D. C.; Glaux, C.; Samsatly, J.; Asaad, S.; Moukahel, A. R.; Gonçalves, F. L. T.; Bigg, E. K.

    2013-04-01

    Various features of the biology of the rust fungi and of the epidemiology of the plant diseases they cause illustrate the important role of rainfall in their life history. Based on this insight we have characterized the ice nucleation activity (INA) of the aerially disseminated spores (urediospores) of this group of fungi. Urediospores of this obligate plant parasite were collected from natural infections of 7 species of weeds in France, from coffee in Brazil and from field and greenhouse-grown wheat in France, the USA, Turkey and Syria. Immersion freezing was used to determine freezing onset temperatures and the abundance of ice nuclei in suspensions of washed spores. Microbiological analyses of spores from France, the USA and Brazil, and subsequent tests of the ice nucleation activity of the bacteria associated with spores were deployed to quantify the contribution of bacteria to the ice nucleation activity of the spores. All samples of spores were ice nucleation active, having freezing onset temperatures as high as -4 °C. Spores in most of the samples carried cells of ice nucleation-active strains of the bacterium Pseudomonas syringae (at rates of less than 1 bacterial cell per 100 urediospores), but bacterial INA accounted for only a small fraction of the INA observed in spore suspensions. Changes in the INA of spore suspensions after treatment with lysozyme suggest that the INA of urediospores involves a polysaccharide. Based on data from the literature, we have estimated the concentrations of urediospores in air at cloud height and in rainfall. These quantities are very similar to those reported for other biological ice nucleators in these same substrates. However, at cloud level convective activity leads to widely varying concentrations of particles of surface origin, so that mean concentrations can underestimate their possible effects on clouds. We propose that spatial and temporal concentrations of biological ice nucleators active at temperatures > -10

  10. Total Skin Electron Beam for Primary Cutaneous T-cell Lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Elsayad, Khaled; Kriz, Jan; Moustakis, Christos; Scobioala, Sergiu; Reinartz, Gabriele; Haverkamp, Uwe; Willich, Normann [Department of Radiation Oncology, University Hospital of Muenster, Muenster (Germany); Weishaupt, Carsten [Department of Dermatology, University Hospital of Muenster, Muenster (Germany); Stadler, Rudolf [Department of Dermatology, Johannes-Wesling-Klinikum Minden, Minden (Germany); Sunderkötter, Cord [Department of Dermatology, University Hospital of Muenster, Muenster (Germany); Eich, Hans Theodor, E-mail: Hans.Eich@ukmuenster.de [Department of Radiation Oncology, University Hospital of Muenster, Muenster (Germany)

    2015-12-01

    Purpose: Recent trials with low-dose total skin electron beam (TSEB) therapy demonstrated encouraging results for treating primary cutaneous T-cell lymphoma (PCTCL). In this study, we assessed the feasibility of different radiation doses and estimated survival rates of different pathologic entities and stages. Methods and Materials: We retrospectively identified 45 patients with PCTCL undergoing TSEB therapy between 2000 and 2015. Clinical characteristics, treatment outcomes, and toxicity were assessed. Results: A total of 49 courses of TSEB therapy were administered to the 45 patients. There were 26 pathologically confirmed cases of mycosis fungoides (MF) lymphoma, 10 cases of Sézary syndrome (SS), and 9 non-MF/SS PCTCL patients. In the MF patients, the overall response rate (ORR) was 92% (50% complete remission [CR]), 70% ORR in SS patients (50% CR), and 89% ORR in non-MF/SS patients (78% CR). The ORR for MF/SS patients treated with conventional dose (30-36 Gy) regimens was 92% (63% CR) and 75% (25% CR) for low-dose (<30-Gy) regimens (P=.09). In MF patients, the overall survival (OS) was 77 months with conventional dose regimens versus 14 months with low-dose regimens (P=.553). In SS patients, the median OS was 48 versus 16 months (P=.219), respectively. Median event-free survival (EFS) for MF in conventional dose patients versus low-dose patients was 15 versus 8 months, respectively (P=.264) and 19 versus 3 months for SS patients (P=.457). Low-dose regimens had shorter treatment time (P=.009) and lower grade 2 adverse events (P=.043). A second TSEB course was administered in 4 MF patients with 100% ORR. There is a possible prognostic impact of supplemental/boost radiation (P<.001); adjuvant treatment (P<.001) and radiation tolerability (P=.021) were detected. Conclusions: TSEB therapy is an efficacious treatment modality in the treatment of several forms of cutaneous T-cell lymphoma. There is a nonsignificant trend to higher and longer clinical benefit

  11. Total pancreatectomy with islet cell autotransplantation as the initial treatment for minimal-change chronic pancreatitis.

    Science.gov (United States)

    Wilson, Gregory C; Sutton, Jeffrey M; Smith, Milton T; Schmulewitz, Nathan; Salehi, Marzieh; Choe, Kyuran A; Brunner, John E; Abbott, Daniel E; Sussman, Jeffrey J; Ahmad, Syed A

    2015-03-01

    Patients with minimal-change chronic pancreatitis (MCCP) are traditionally managed medically with poor results. This study was conducted to review outcomes following total pancreatectomy with islet cell autotransplantation (TP/IAT) as the initial surgical procedure in the treatment of MCCP. All patients submitted to TP/IAT for MCCP were identified for inclusion in a single-centre observational study. A retrospective chart review was performed to identify pertinent preoperative, perioperative and postoperative data. A total of 84 patients with a mean age of 36.5 years (range: 15-60 years) underwent TP/IAT as the initial treatment for MCCP. The most common aetiology of chronic pancreatitis in this cohort was idiopathic (69.0%, n = 58), followed by aetiologies associated with genetic mutations (16.7%, n = 14), pancreatic divisum (9.5%, n = 8), and alcohol (4.8%, n = 4). The most common genetic mutations pertained to CFTR (n = 9), SPINK1 (n = 3) and PRSS1 (n = 2). Mean ± standard error of the mean preoperative narcotic requirements were 129.3 ± 18.7 morphine-equivalent milligrams (MEQ)/day. Overall, 58.3% (n = 49) of patients achieved narcotic independence and the remaining patients required 59.4 ± 10.6 MEQ/day (P < 0.05). Postoperative insulin independence was achieved by 36.9% (n = 31) of patients. The Short-Form 36-Item Health Survey administered postoperatively demonstrated improvement in all tested quality of life subscales. The present report represents one of the largest series demonstrating the benefits of TP/IAT in the subset of patients with MCCP. © 2014 International Hepato-Pancreato-Biliary Association.

  12. Outcomes following total laryngectomy for squamous cell carcinoma: one centre experience.

    Science.gov (United States)

    Leong, S C; Kartha, S-S; Kathan, C; Sharp, J; Mortimore, S

    2012-12-01

    To evaluate the clinical outcomes of total laryngectomy (TL), complications and factors affecting survival. Retrospective review of hospital electronic database for head and neck squamous cell carcinoma (SCCa). Large district general hospital in England, United Kingdom. Patients who had TL between January 1994 and January 2008. 5-year disease specific survival (DSS) and disease-free survival (DFS). Seventy-one patients were reviewed, of whom 38 (54%) had laryngeal SCCa and 33 (46%) hypopharyngeal SCCa. The overall mean survival period following TL was 42.4 months. The 5-year DSS and DFS was better for laryngeal SCCa compared to hypopharyngeal SCCa, although not statistically significant (P=0.090, P=0.54 respectively). Patients treated for laryngeal SCCa had a mean survival period of 47.5 months compared to 36.5 months for hypopharyngeal disease. Those who had laryngeal recurrence after primary radiotherapy (RT) demonstrated statistically better survival probability than those who had hypopharyngeal recurrence (P=0.011). Patients without cervical lymphadenopathy had statistically better survival (P=0.049). The most common early complication was related to the cardiorespiratory system. One fatal complication of erosion of the brachiocephalic artery due to the laryngectomy tube was noted. The most common late complication was neopharyngeal stenosis. The commonest cause of death was due to locoregional recurrence, followed by medical co-morbidities. Patients referred to specialised head and neck clinic had a better survival probability than those referred to a general ENT clinic (P=0.37). While there is increasing tendency towards laryngeal conservation, total laryngectomy remains a robust treatment option in selected patients. Copyright © 2012. Published by Elsevier Masson SAS.

  13. Epitaxial Nucleation on Rationally Designed Peptide Functionalized Interface

    Science.gov (United States)

    2011-07-19

    is dissolved in the subphase of the Langmuir Blodgett trough. We do not add a reductant to the subphase to initiate the nucleation process... ionic liquids41 and C18-imidazole surfactants44. In the case of the ionic liquid study, higher concentrations produce plate-like particles similar...phase behavior. We characterize the phase behavior by using Langmuir techniques, Brewster Angle Microscopy, Attenuated Total Reflection Fourier

  14. Nucleation at high pressure I: Theoretical considerations.

    NARCIS (Netherlands)

    Luijten, C.C.M.; Dongen, van M.E.H.

    1999-01-01

    A theoretical approach is presented that accounts for the influence of high pressure background gases on the vapor-to-liquid nucleation process. The key idea is to treat the carrier gas pressure as a perturbation parameter that modifies the properties of the nucleating substance. Two important

  15. Simple improvements to classical bubble nucleation models.

    Science.gov (United States)

    Tanaka, Kyoko K; Tanaka, Hidekazu; Angélil, Raymond; Diemand, Jürg

    2015-08-01

    We revisit classical nucleation theory (CNT) for the homogeneous bubble nucleation rate and improve the classical formula using a correct prefactor in the nucleation rate. Most of the previous theoretical studies have used the constant prefactor determined by the bubble growth due to the evaporation process from the bubble surface. However, the growth of bubbles is also regulated by the thermal conduction, the viscosity, and the inertia of liquid motion. These effects can decrease the prefactor significantly, especially when the liquid pressure is much smaller than the equilibrium one. The deviation in the nucleation rate between the improved formula and the CNT can be as large as several orders of magnitude. Our improved, accurate prefactor and recent advances in molecular dynamics simulations and laboratory experiments for argon bubble nucleation enable us to precisely constrain the free energy barrier for bubble nucleation. Assuming the correction to the CNT free energy is of the functional form suggested by Tolman, the precise evaluations of the free energy barriers suggest the Tolman length is ≃0.3σ independently of the temperature for argon bubble nucleation, where σ is the unit length of the Lennard-Jones potential. With this Tolman correction and our prefactor one gets accurate bubble nucleation rate predictions in the parameter range probed by current experiments and molecular dynamics simulations.

  16. Nucleation in an ultra low ionisation environment

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker

    in aerosol nucleation. By exposing a controlled volume of air to varying levels of ionising radiation, and with the minimum ionisation level vastly reduced compared to normal surface laboratory conditions, we have provided both a validation of earlier studies of ion-induced nucleation and extended...

  17. Tuning Ice Nucleation with Supercharged Polypeptides

    NARCIS (Netherlands)

    Yang, Huige; Ma, Chao; Li, Kaiyong; Liu, Kai; Loznik, Mark; Teeuwen, Rosalie; van Hest, Jan C. M.; Zhou, Xin; Herrmann, Andreas; Wang, Jianjun

    2016-01-01

    Supercharged unfolded polypeptides (SUPs) are exploited for controlling ice nucleation via tuning the nature of charge and charge density of SUPs. The results show that positively charged SUPs facilitate ice nucleation, while negatively charged ones suppress it. Moreover, the charge density of the

  18. Nucleation and Growth of GaN on GaAs (001) Substrates

    International Nuclear Information System (INIS)

    Drummond, Timothy J.; Hafich, Michael J.; Heller, Edwin J.; Lee, Stephen R.; Liliental-Weber, Zuzanna; Ruvimov, Sergei; Sullivan, John P.

    1999-01-01

    The nucleation of GaN thin films on GaAs is investigated for growth at 620 ''C. An rf plasma cell is used to generate chemically active nitrogen from N 2 . An arsenic flux is used in the first eight monolayer of nitride growth to enhance nucleation of the cubic phase. Subsequent growth does not require an As flux to preserve the cubic phase. The nucleation of smooth interfaces and GaN films with low stacking fault densities is dependent upon relative concentrations of active nitrogen species in the plasma and on the nitrogen to gallium flux ratio

  19. Nucleation and growth of new particles in Po Valley, Italy

    Directory of Open Access Journals (Sweden)

    A. Hamed

    2007-01-01

    Full Text Available Aerosol number distribution measurements are reported at San Pietro Capofiume (SPC station (44°39' N, 11°37' E for the time period 2002–2005. The station is located in Po Valley, the largest industrial, trading and agricultural area in Italy with a high population density. New particle formation was studied based on observations of the particle size distribution, meteorological and gas phase parameters. The nucleation events were classified according to the event clarity based on the particle number concentrations, and the particle formation and growth rates. Out of a total of 769 operational days from 2002 to 2005 clear events were detected on 36% of the days whilst 33% are clearly non-event days. The event frequency was high during spring and summer months with maximum values in May and July, whereas lower frequency was observed in winter and autumn months. The average particle formation and growth rates were estimated as ~6 cm−3 s−1 and ~7 nm h−1, respectively. Such high growth and formation rates are typical for polluted areas. Temperature, wind speed, solar radiation, SO2 and O3 concentrations were on average higher on nucleation days than on non-event days, whereas relative and absolute humidity and NO2 concentration were lower; however, seasonal differences were observed. Backtrajectory analysis suggests that during majority of nucleation event days, the air masses originate from northern to eastern directions. We also study previously developed nucleation event correlations with environmental variables and show that they predict Po Valley nucleation events with variable success.

  20. 28Si total body irradiation injures bone marrow hematopoietic stem cells via induction of cellular apoptosis

    Science.gov (United States)

    Chang, Jianhui; Feng, Wei; Wang, Yingying; Allen, Antiño R.; Turner, Jennifer; Stewart, Blair; Raber, Jacob; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2017-05-01

    Long-term space mission exposes astronauts to a radiation environment with potential health hazards. High-energy charged particles (HZE), including 28Si nuclei in space, have deleterious effects on cells due to their characteristics with high linear energy transfer and dense ionization. The influence of 28Si ions contributes more than 10% to the radiation dose equivalent in the space environment. Understanding the biological effects of 28Si irradiation is important to assess the potential health hazards of long-term space missions. The hematopoietic system is highly sensitive to radiation injury and bone marrow (BM) suppression is the primary life-threatening injuries after exposure to a moderate dose of radiation. Therefore, in the present study we investigated the acute effects of low doses of 28Si irradiation on the hematopoietic system in a mouse model. Specifically, 6-month-old C57BL/6 J mice were exposed to 0.3, 0.6 and 0.9 Gy 28Si (600 MeV) total body irradiation (TBI). The effects of 28Si TBI on BM hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) were examined four weeks after the exposure. The results showed that exposure to 28Si TBI dramatically reduced the frequencies and numbers of HSCs in irradiated mice, compared to non-irradiated controls, in a radiation dose-dependent manner. In contrast, no significant changes were observed in BM HPCs regardless of radiation doses. Furthermore, irradiated HSCs exhibited a significant impairment in clonogenic ability. These acute effects of 28Si irradiation on HSCs may be attributable to radiation-induced apoptosis of HSCs, because HSCs, but not HPCs, from irradiated mice exhibited a significant increase in apoptosis in a radiation dose-dependent manner. However, exposure to low doses of 28Si did not result in an increased production of reactive oxygen species and DNA damage in HSCs and HPCs. These findings indicate that exposure to 28Si irradiation leads to acute HSC damage.

  1. Damage instability and Earthquake nucleation

    Science.gov (United States)

    Ionescu, I. R.; Gomez, Q.; Campillo, M.; Jia, X.

    2017-12-01

    Earthquake nucleation (initiation) is usually associated to the loss of the stability of the geological structure under a slip-weakening friction acting on the fault. The key parameters involved in the stability of the fault are the stress drop, the critical slip distance but also the elastic stiffness of the surrounding materials (rocks). We want to explore here how the nucleation phenomena are correlated to the material softening during damage accumulation by dynamic and/or quasi-static processes. Since damage models are describing micro-cracks growth, which is generally an unstable phenomenon, it is natural to expect some loss of stability on the associated micro-mechanics based models. If the model accurately captures the material behavior, then this can be due to the unstable nature of the brittle material itself. We obtained stability criteria at the microscopic scale, which are related to a large class of damage models. We show that for a given continuous strain history the quasi-static or dynamic problems are instable or ill-posed (multiplicity of material responses) and whatever the selection rule is adopted, shocks (time discontinuities) will occur. We show that the quasi-static equilibria chosen by the "perfect delay convention" is always stable. These stability criteria are used to analyze how NIC (Non Interacting Crack) effective elasticity associated to "self similar growth" model work in some special configurations (one family of micro-cracks in mode I, II and III and in plane strain or plain stress). In each case we determine a critical crack density parameter and critical micro-crack radius (length) which distinguish between stable and unstable behaviors. This critical crack density depends only on the chosen configuration and on the Poisson ratio.

  2. Chemically assisted crack nucleation in zircaloy

    International Nuclear Information System (INIS)

    Williford, R.E.

    1985-01-01

    Stress corrosion cracking models (proposed to explain fuel rod failures) generally address crack propagation and cladding rupture, but frequently neglect the necessary nucleation stage for microcracks small enough to violate fracture mechanics continuum requirements. Intergranular microcrack nucleation was modeled with diffusion-controlled grain-boundary cavitation concepts, including the effects of metal embrittlement by iodine species. Computed microcrack nucleation times and strains agree with experimental observation, but the predicted grain-boundary cavities are so small that detection may be difficult. Without a protective oxide film intergranular microcracks can nucleate within 30 s at even low stresses when the embrittler concentration exceeds a threshold value. Indications were found that intergranular microcrack nucleation may be caused by combined corrosive and embrittlement phenomena. (orig.)

  3. Sensing methanol concentration in direct methanol fuel cell with total harmonic distortion: Theory and application

    International Nuclear Information System (INIS)

    Mao Qing; Krewer, Ulrike

    2012-01-01

    The nonlinear frequency response of a direct methanol fuel cell (DMFC) is studied by analyzing the total harmonic distortion (THD) spectra. The dependence of the THD spectra on methanol concentration and methanol oxidation kinetics is investigated by means of both simulation and experiment. Simulation using a continuous stirred tank reactor network model suggests that the methanol concentration profile in the anode has a strong impact on the THD spectra. The experimentally observed nonlinear behavior of the DMFC anode can be qualitatively reproduced with a model containing a three-step methanol oxidation mechanism with Kauranen–Frumkin/Temkin kinetics. Both experiment and simulation results show that THD value has a monotonic correlation with methanol concentration at certain frequencies and its sensitivity to concentration is improved with increased current amplitude. The monotonic relationship enables the THD to sense the methanol concentration level by the DMFC itself, which is of mayor interest for the portable application as an external sensor for the system can be omitted.

  4. Role of stacking disorder in ice nucleation.

    Science.gov (United States)

    Lupi, Laura; Hudait, Arpa; Peters, Baron; Grünwald, Michael; Gotchy Mullen, Ryan; Nguyen, Andrew H; Molinero, Valeria

    2017-11-08

    The freezing of water affects the processes that determine Earth's climate. Therefore, accurate weather and climate forecasts hinge on good predictions of ice nucleation rates. Such rate predictions are based on extrapolations using classical nucleation theory, which assumes that the structure of nanometre-sized ice crystallites corresponds to that of hexagonal ice, the thermodynamically stable form of bulk ice. However, simulations with various water models find that ice nucleated and grown under atmospheric temperatures is at all sizes stacking-disordered, consisting of random sequences of cubic and hexagonal ice layers. This implies that stacking-disordered ice crystallites either are more stable than hexagonal ice crystallites or form because of non-equilibrium dynamical effects. Both scenarios challenge central tenets of classical nucleation theory. Here we use rare-event sampling and free energy calculations with the mW water model to show that the entropy of mixing cubic and hexagonal layers makes stacking-disordered ice the stable phase for crystallites up to a size of at least 100,000 molecules. We find that stacking-disordered critical crystallites at 230 kelvin are about 14 kilojoules per mole of crystallite more stable than hexagonal crystallites, making their ice nucleation rates more than three orders of magnitude higher than predicted by classical nucleation theory. This effect on nucleation rates is temperature dependent, being the most pronounced at the warmest conditions, and should affect the modelling of cloud formation and ice particle numbers, which are very sensitive to the temperature dependence of ice nucleation rates. We conclude that classical nucleation theory needs to be corrected to include the dependence of the crystallization driving force on the size of the ice crystallite when interpreting and extrapolating ice nucleation rates from experimental laboratory conditions to the temperatures that occur in clouds.

  5. Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

    Science.gov (United States)

    Lisle, John T.; Robbins, Lisa L.

    2016-01-01

    Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC) that is currently not accounted for

  6. Evaluation of the impact of banking umbilical cord blood units with high cell dose for ethnically diverse patients.

    Science.gov (United States)

    Stritesky, Gretta; Wadsworth, Kimberly; Duffy, Merry; Buck, Kelly; Dehn, Jason

    2018-02-01

    Umbilical cord blood units provide an important stem cell source for transplantation, particularly for patients of ethnic diversity who may not have suitably matched available, adult-unrelated donors. However, with the cost of cord blood unit acquisition from public banks significantly higher than that for adult-unrelated donors, attention is focused on decreasing cost yet still providing cord blood units to patients in need. Historical practices of banking units with low total nucleated cell counts, including units with approximately 90 × 10 7 total nucleated cells, indicates that most banked cord blood units have much lower total nucleated cell counts than are required for transplant. The objective of this study was to determine the impact on the ability to identify suitable cord blood units for transplantation if the minimum total nucleated cell count for banking were increased from 90 × 10 7 to 124 or 149 × 10 7 . We analyzed ethnically diverse patients (median age, 3 years) who underwent transplantation of a single cord blood unit in 2005 to 2016. A cord blood unit search was evaluated to identify units with equal or greater human leukocyte antigen matching and a greater total nucleated cell count than that of the transplanted cord blood unit (the replacement cord blood unit). If the minimum total nucleated cell count for banking increased to 124 or 149 × 10 7 , then from 75 to 80% of patients would still have at least 1 replacement cord blood unit in the current (2016) cord blood unit inventory. The best replacement cord blood units were often found among cords with the same ethnic background as the patient. The current data suggest that, if the minimum total nucleated cell count were increased for banking, then it would likely lead to an inventory of more desirable cord blood units while having minimal impact on the identification of suitable cord blood units for transplantation. © 2017 AABB.

  7. Nonrandom γ-TuNA-dependent spatial pattern of microtubule nucleation at the Golgi.

    Science.gov (United States)

    Sanders, Anna A W M; Chang, Kevin; Zhu, Xiaodong; Thoppil, Roslin J; Holmes, William R; Kaverina, Irina

    2017-11-07

    Noncentrosomal microtubule (MT) nucleation at the Golgi generates MT network asymmetry in motile vertebrate cells. Investigating the Golgi-derived MT (GDMT) distribution, we find that MT asymmetry arises from nonrandom nucleation sites at the Golgi (hotspots). Using computational simulations, we propose two plausible mechanistic models of GDMT nucleation leading to this phenotype. In the "cooperativity" model, formation of a single GDMT promotes further nucleation at the same site. In the "heterogeneous Golgi" model, MT nucleation is dramatically up-regulated at discrete and sparse locations within the Golgi. While MT clustering in hotspots is equally well described by both models, simulating MT length distributions within the cooperativity model fits the data better. Investigating the molecular mechanism underlying hotspot formation, we have found that hotspots are significantly smaller than a Golgi subdomain positive for scaffolding protein AKAP450, which is thought to recruit GDMT nucleation factors. We have further probed potential roles of known GDMT-promoting molecules, including γ-TuRC-mediated nucleation activator (γ-TuNA) domain-containing proteins and MT stabilizer CLASPs. While both γ-TuNA inhibition and lack of CLASPs resulted in drastically decreased GDMT nucleation, computational modeling revealed that only γ-TuNA inhibition suppressed hotspot formation. We conclude that hotspots require γ-TuNA activity, which facilitates clustered GDMT nucleation at distinct Golgi sites. © 2017 Sanders 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).

  8. Stereological quantification of tumor volume, mean nuclear volume and total number of melanoma cells correlated with morbidity and mortality

    DEFF Research Database (Denmark)

    Bønnelykke-Behrndtz, Marie Louise; Sørensen, Flemming Brandt; Damsgaard, Tine Engberg

    2008-01-01

    potential indicators of prognosis. Sixty patients who underwent surgery at the Department of Plastic Surgery, Aarhus University Hospital, from 1991 to 1994 were included in the study. Total tumor volume was estimated by the Cavalieri technique, total number of tumor cells by the optical dissector principle...... showed a significant impact on both disease-free survival (p=0.001) and mortality (p=0.009). In conclusion, tumor volume and total number of cancer cells were highly reproducible but did not add additional, independent prognostic information regarding the study population.......Stereological quantification of tumor volume, total number of tumor cells and mean nuclear volume provides unbiased data, regardless of the three-dimensional shape of the melanocytic lesion. The aim of the present study was to investigate whether these variables are reproducible and may represent...

  9. GIT1/βPIX signaling proteins and PAK1 kinase regulate microtubule nucleation.

    Science.gov (United States)

    Černohorská, Markéta; Sulimenko, Vadym; Hájková, Zuzana; Sulimenko, Tetyana; Sládková, Vladimíra; Vinopal, Stanislav; Dráberová, Eduarda; Dráber, Pavel

    2016-06-01

    Microtubule nucleation from γ-tubulin complexes, located at the centrosome, is an essential step in the formation of the microtubule cytoskeleton. However, the signaling mechanisms that regulate microtubule nucleation in interphase cells are largely unknown. In this study, we report that γ-tubulin is in complexes containing G protein-coupled receptor kinase-interacting protein 1 (GIT1), p21-activated kinase interacting exchange factor (βPIX), and p21 protein (Cdc42/Rac)-activated kinase 1 (PAK1) in various cell lines. Immunofluorescence microscopy revealed association of GIT1, βPIX and activated PAK1 with centrosomes. Microtubule regrowth experiments showed that depletion of βPIX stimulated microtubule nucleation, while depletion of GIT1 or PAK1 resulted in decreased nucleation in the interphase cells. These data were confirmed for GIT1 and βPIX by phenotypic rescue experiments, and counting of new microtubules emanating from centrosomes during the microtubule regrowth. The importance of PAK1 for microtubule nucleation was corroborated by the inhibition of its kinase activity with IPA-3 inhibitor. GIT1 with PAK1 thus represent positive regulators, and βPIX is a negative regulator of microtubule nucleation from the interphase centrosomes. The regulatory roles of GIT1, βPIX and PAK1 in microtubule nucleation correlated with recruitment of γ-tubulin to the centrosome. Furthermore, in vitro kinase assays showed that GIT1 and βPIX, but not γ-tubulin, serve as substrates for PAK1. Finally, direct interaction of γ-tubulin with the C-terminal domain of βPIX and the N-terminal domain of GIT1, which targets this protein to the centrosome, was determined by pull-down experiments. We propose that GIT1/βPIX signaling proteins with PAK1 kinase represent a novel regulatory mechanism of microtubule nucleation in interphase cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Heterogeneous nucleation of calcium oxalate on native oxide surfaces

    International Nuclear Information System (INIS)

    Song, L.; Pattillo, M.J.; Graff, G.L.; Campbell, A.A.; Bunker, B.C.

    1994-04-01

    The aqueous deposition of calcium oxalate onto colloidal oxides has been studied as a model system for understanding heterogeneous nucleation processes of importance in biomimetic synthesis of ceramic thin films. Calcium oxalate nucleation has been monitored by measuring induction times for nucleation using Constant Composition techniques and by measuring nucleation densities on extended oxide surfaces using an atomic force microscope. Results show that the dependence of calcium oxalate nucleation on solution supersaturation fits the functional form predicted by classical nucleation theories. Anionic surfaces appear to promote nucleation better than cationic surfaces, lowering the effective energy barrier to heterogeneous nucleation

  11. Texture control and seeded nucleation of nanosize structures of ferroelectric thin films

    Science.gov (United States)

    Muralt, Paul

    2006-09-01

    An overview is given on nucleation phenomena of Pb(Zr ,Ti)O3 (PZT) thin films on Pt(111)-based substrates. Emphasis is given on in situ growth methods, particularly in situ reactive sputtering from three metallic targets. Growth of PZT thin films is discussed from the point of view of the PbOx-TiO2 phase diagram, PbO vapor pressure, and classical nucleation theory. The role of thin TiO2 affinity layers and spots is explained in the frame of this theory. Activation energies for desorption and chemisorption are adapted to comply with the fact that nucleation rates on TiO2 are much larger than the ones on bare Pt(111). The model reproduces well the PbO surface flux from bare Pt(111) to the affinity spots in the case of PbTiO3 nucleation and the reversed tendency in the case of PZT 40/60 nucleation, explaining experimental observations. The critical size of nuclei was calculated to contain 8-10unit cells for PbTiO3/Pt nucleation and 14-17 for PZT/Pt nucleation.

  12. Adhesion of living cells revealed by variable-angle total internal reflection fluorescence microscopy (Conference Presentation)

    Science.gov (United States)

    Cardoso Dos Santos, Marcelina; Vézy, Cyrille; Jaffiol, Rodolphe

    2016-02-01

    Total Internal Reflection Fluorescence Microscopy (TIRFM) is a widespread technique to study cellular process occurring near the contact region with the glass substrate. In this field, determination of the accurate distance from the surface to the plasma membrane constitutes a crucial issue to investigate the physical basis of cellular adhesion process. However, quantitative interpretation of TIRF pictures regarding the distance z between a labeled membrane and the substrate is not trivial. Indeed, the contrast of TIRF images depends on several parameters more and less well known (local concentration of dyes, absorption cross section, angular emission pattern…). The strategy to get around this problem is to exploit a series of TIRF pictures recorded at different incident angles in evanescent regime. This technique called variable-angle TIRF microscopy (vaTIRFM), allowing to map the membrane-substrate separation distance with a nanometric resolution (10-20 nm). vaTIRFM was developed by Burmeister, Truskey and Reichert in the early 1990s with a prism-based TIRF setup [Journal of Microscopy 173, 39-51 (1994)]. We propose a more convenient prismless setup, which uses only a rotatable mirror to adjust precisely the laser beam on the back focal plane of the oil immersion objective (no azimuthal scanning is needed). The series of TIRF images permit us to calculate accurately membrane-surface distances in each pixel. We demonstrate that vaTIRFM are useful to quantify the adhesion of living cells for specific and unspecific membrane-surface interactions, achieved on various functionalized substrates with polymers (BSA, poly-L-lysin) or extracellular matrix proteins (collagen and fibronectin).

  13. Impact of surface nanostructure on ice nucleation.

    Science.gov (United States)

    Zhang, Xiang-Xiong; Chen, Min; Fu, Ming

    2014-09-28

    Nucleation of water on solid surface can be promoted noticeably when the lattice parameter of a surface matches well with the ice structure. However, the characteristic length of the surface lattice reported is generally less than 0.5 nm and is hardly tunable. In this paper, we show that a surface with nanoscale roughness can also remarkably promote ice nucleation if the characteristic length of the surface structure matches well with the ice crystal. A series of surfaces composed of periodic grooves with same depth but different widths are constructed in molecular dynamics simulations. Water cylinders are placed on the constructed surfaces and frozen at constant undercooling. The nucleation rates of the water cylinders are calculated in the simulation using the mean first-passage time method and then used to measure the nucleation promotion ability of the surfaces. Results suggest that the nucleation behavior of the supercooled water is significantly sensitive to the width of the groove. When the width of the groove matches well with the specific lengths of the ice crystal structure, the nucleation can be promoted remarkably. If the width does not match with the ice crystal, this kind of promotion disappears and the nucleation rate is even smaller than that on the smooth surface. Simulations also indicate that even when water molecules are adsorbed onto the surface structure in high-humidity environment, the solid surface can provide promising anti-icing ability as long as the characteristic length of the surface structure is carefully designed to avoid geometric match.

  14. Nucleation behavior of glutathione polymorphs in water

    International Nuclear Information System (INIS)

    Chen, Zhi; Dang, Leping; Li, Shuai; Wei, Hongyuan

    2013-01-01

    Nucleation behavior of glutathione (GSH) polymorphs in water was investigated by experimental method combined with classical nucleation theory. The solubility of α and β forms GSH in water at different temperatures, and the nucleation induction period at various supersaturations and temperatures were determined experimentally. The results show that, in a certain range of supersaturation, the nucleation of β form predominates at relatively higher temperature, while α form will be obtained at lower temperature. The nucleation kinetics parameters of α and β form were then calculated. To understand the crucial role of temperature on crystal forms, “hypothetic” nucleation parameters of β form at 283.15 K were deduced based on extrapolation method. The results show that the interfacial tension, critical free energy, critical nucleus radius and nucleus number of α form are smaller than that of β form in the same condition at 283.15 K, which implies that α form nucleates easier than β form at low temperature. This work may be useful for the control and optimization of GSH crystallization process in industry

  15. Nucleation of voids - the impurity effect

    International Nuclear Information System (INIS)

    Chen, I-W; Taiwo, A.

    1984-01-01

    Nucleation of voids under irradiation in multicomponent alloys remains an unsolved theoretical problem. Of particular interest are the effects of nonequilibrium solute segregation phenomena on the critical nucleus and the nucleation rate. The resolution of the multicomponent nucleation in a dissipative system also has broader implication to the field of irreversible thermodynamics. The present paper describes a recent study of solute segregation effects in void nucleation. We begin with a thermodynamic model for a nonequilibrium void with interfacial segregation. The thermodynamic model is coupled with kinetic considerations of solute/solvent diffusion under a bias, which is itself related to segregation by the coating effect, to assess the stability of void embryos. To determine nucleation rate, we develop a novel technique by extending the most probable path method in statistical mechanics for nonequilibrium steady state to simulate large fluctuation with nonlinear dissipation. The path of nucleation is determined by solving an analogous problem on particle trajectory in classical dynamics. The results of both the stability analysis and the fluctuation analysis establish the paramount significance of the impurity effect via the mechanism of nonequilibrium segregation. We conclude that over-segregation is probably the most general cause for the apparently low nucleation barriers that are responsible for nearly ubiquitous occurrence of void swelling in common metals

  16. Nonclassical nucleation pathways in protein crystallization.

    Science.gov (United States)

    Zhang, Fajun

    2017-11-08

    Classical nucleation theory (CNT), which was established about 90 years ago, has been very successful in many research fields, and continues to be the most commonly used theory in describing the nucleation process. For a fluid-to-solid phase transition, CNT states that the solute molecules in a supersaturated solution reversibly form small clusters. Once the cluster size reaches a critical value, it becomes thermodynamically stable and favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists between the initial supersaturated solution and the final crystals. Depending on the exact free energy landscapes, the MIPs can be a high density liquid phase, mesoscopic clusters, or a pre-ordered state. In this review, we focus on the studies of nonclassical pathways in protein crystallization and discuss the applications of the various scenarios of two-step nucleation theory. In particular, we focus on protein solutions in the presence of multivalent salts, which serve as a model protein system to study the nucleation pathways. We wish to point out the unique features of proteins as model systems for further studies.

  17. Heat transfer enhancement on nucleate boiling

    International Nuclear Information System (INIS)

    Zhuang, M.; Guibai, L.

    1990-01-01

    This paper reports on enhancement of nucleate boiling heat transfer with additives that was investigated experimentally. More than fifteen kinds of additives were chosen and tested. Eight kinds of effective additives which can enhance nucleate boiling heat transfer were selected. Experimental results showed that boiling heat transfer coefficient of water was increased by 1 to 5 times and that of R-113 was increased by 1 to 4 times when trace amount additives were put in the two boiling liquids. There exist optimum concentrations for the additives, respectively, which can enhance nucleate boiling heat transfer rate best. In order to analyze the mechanism of the enhancement of boiling heat transfer with additives, the surface tension and the bubble departure diameter were measured. The nucleation sites were investigated by use of high-speed photograph. Experimental results showed that nucleation sites increase with additive amount increasing and get maximum. Increasing nucleation sites is one of the most important reason why nucleate boiling heat transfer can be enhanced with additives

  18. Nonclassical nucleation pathways in protein crystallization

    Science.gov (United States)

    Zhang, Fajun

    2017-11-01

    Classical nucleation theory (CNT), which was established about 90 years ago, has been very successful in many research fields, and continues to be the most commonly used theory in describing the nucleation process. For a fluid-to-solid phase transition, CNT states that the solute molecules in a supersaturated solution reversibly form small clusters. Once the cluster size reaches a critical value, it becomes thermodynamically stable and favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists between the initial supersaturated solution and the final crystals. Depending on the exact free energy landscapes, the MIPs can be a high density liquid phase, mesoscopic clusters, or a pre-ordered state. In this review, we focus on the studies of nonclassical pathways in protein crystallization and discuss the applications of the various scenarios of two-step nucleation theory. In particular, we focus on protein solutions in the presence of multivalent salts, which serve as a model protein system to study the nucleation pathways. We wish to point out the unique features of proteins as model systems for further studies.

  19. Bioinspired Materials for Controlling Ice Nucleation, Growth, and Recrystallization.

    Science.gov (United States)

    He, Zhiyuan; Liu, Kai; Wang, Jianjun

    2018-05-15

    Ice formation, mainly consisting of ice nucleation, ice growth, and ice recrystallization, is ubiquitous and crucial in wide-ranging fields from cryobiology to atmospheric physics. Despite active research for more than a century, the mechanism of ice formation is still far from satisfactory. Meanwhile, nature has unique ways of controlling ice formation and can provide resourceful avenues to unravel the mechanism of ice formation. For instance, antifreeze proteins (AFPs) protect living organisms from freezing damage via controlling ice formation, for example, tuning ice nucleation, shaping ice crystals, and inhibiting ice growth and recrystallization. In addition, AFP mimics can have applications in cryopreservation of cells, tissues, and organs, food storage, and anti-icing materials. Therefore, continuous efforts have been made to understand the mechanism of AFPs and design AFP inspired materials. In this Account, we first review our recent research progress in understanding the mechanism of AFPs in controlling ice formation. A Janus effect of AFPs on ice nucleation was discovered, which was achieved via selectively tethering the ice-binding face (IBF) or the non-ice-binding face (NIBF) of AFPs to solid surfaces and investigating specifically the effect of the other face on ice nucleation. Through molecular dynamics (MD) simulation analysis, we observed ordered hexagonal ice-like water structure atop the IBF and disordered water structure atop the NIBF. Therefore, we conclude that the interfacial water plays a critical role in controlling ice formation. Next, we discuss the design and fabrication of AFP mimics with capabilities in tuning ice nucleation and controlling ice shape and growth, as well as inhibiting ice recrystallization. For example, we tuned ice nucleation via modifying solid surfaces with supercharged unfolded polypeptides (SUPs) and polyelectrolyte brushes (PBs) with different counterions. We found graphene oxide (GO) and oxidized quasi

  20. Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis

    Science.gov (United States)

    Borek, Weronika E.; Groocock, Lynda M.; Samejima, Itaru; Zou, Juan; de Lima Alves, Flavia; Rappsilber, Juri; Sawin, Kenneth E.

    2015-01-01

    Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. PMID:26243668

  1. The total number of Leydig and Sertoli cells in the testes of men across various age groups - a stereological study

    DEFF Research Database (Denmark)

    Petersen, Peter M; Seierøe, Karina; Pakkenberg, Bente

    2015-01-01

    is particularly sensitive to methodological problems. Therefore, using the optical fractionator technique and a sampling design specifically optimized for human testes, we estimated the total number of Sertoli and Leydig cells in the testes from 26 post mortem male subjects ranging in age from 16 to 80 years...... of Sertoli cells with age; no such decline was found for Leydig cells. Quantitative stereological analysis of post mortem tissue may help understand the influence of age or disease on the number of human testicular cells....

  2. Total glucosides of paeony inhibits lipopolysaccharide-induced proliferation, migration and invasion in androgen insensitive prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Zhi-Hui Zhang

    Full Text Available Previous studies demonstrated that inflammatory microenvironment promoted prostate cancer progression. This study investigated whether total glucosides of paeony (TGP, the active constituents extracted from the root of Paeonia Lactiflora Pall, suppressed lipopolysaccharide (LPS-stimulated proliferation, migration and invasion in androgen insensitive prostate cancer cells. PC-3 cells were incubated with LPS (2.0 μg/mL in the absence or presence of TGP (312.5 μg /mL. As expected, cells at S phase and nuclear CyclinD1, the markers of cell proliferation, were increased in LPS-stimulated PC-3 cells. Migration activity, as determined by wound-healing assay and transwell migration assay, and invasion activity, as determined by transwell invasion assay, were elevated in LPS-stimulated PC-3 cells. Interestingly, TGP suppressed LPS-stimulated PC-3 cells proliferation. Moreover, TGP inhibited LPS-stimulated migration and invasion of PC-3 cells. Additional experiment showed that TGP inhibited activation of nuclear factor kappa B (NF-κB and mitogen-activated protein kinase (MAPK/p38 in LPS-stimulated PC-3 cells. Correspondingly, TGP attenuated upregulation of interleukin (IL-6 and IL-8 in LPS-stimulated PC-3 cells. In addition, TGP inhibited nuclear translocation of signal transducer and activator of transcription 3 (STAT3 in LPS-stimulated PC-3 cells. These results suggest that TGP inhibits inflammation-associated STAT3 activation and proliferation, migration and invasion in androgen insensitive prostate cancer cells.

  3. Immobile defects in ferroelastic walls: Wall nucleation at defect sites

    Science.gov (United States)

    He, X.; Salje, E. K. H.; Ding, X.; Sun, J.

    2018-02-01

    Randomly distributed, static defects are enriched in ferroelastic domain walls. The relative concentration of defects in walls, Nd, follows a power law distribution as a function of the total defect concentration C: N d ˜ C α with α = 0.4 . The enrichment Nd/C ranges from ˜50 times when C = 10 ppm to ˜3 times when C = 1000 ppm. The resulting enrichment is due to nucleation at defect sites as observed in large scale MD simulations. The dynamics of domain nucleation and switching is dependent on the defect concentration. Their energy distribution follows the power law with exponents during yield between ɛ ˜ 1.82 and 2.0 when the defect concentration increases. The power law exponent is ɛ ≈ 2.7 in the plastic regime, independent of the defect concentration.

  4. Complementary activities of TPX2 and chTOG constitute an efficient importin-regulated microtubule nucleation module.

    Science.gov (United States)

    Roostalu, Johanna; Cade, Nicholas I; Surrey, Thomas

    2015-11-01

    Spindle assembly and function require precise control of microtubule nucleation and dynamics. The chromatin-driven spindle assembly pathway exerts such control locally in the vicinity of chromosomes. One of the key targets of this pathway is TPX2. The molecular mechanism of how TPX2 stimulates microtubule nucleation is not understood. Using microscopy-based dynamic in vitro reconstitution assays with purified proteins, we find that human TPX2 directly stabilizes growing microtubule ends and stimulates microtubule nucleation by stabilizing early microtubule nucleation intermediates. Human microtubule polymerase chTOG (XMAP215/Msps/Stu2p/Dis1/Alp14 homologue) only weakly promotes nucleation, but acts synergistically with TPX2. Hence, a combination of distinct and complementary activities is sufficient for efficient microtubule formation in vitro. Importins control the efficiency of the microtubule nucleation by selectively blocking the interaction of TPX2 with microtubule nucleation intermediates. This in vitro reconstitution reveals the molecular mechanism of regulated microtubule formation by a minimal nucleation module essential for chromatin-dependent microtubule nucleation in cells.

  5. Damage nucleation in Si during ion irradiation

    International Nuclear Information System (INIS)

    Holland, O.W.; Fathy, D.; Narayan, J.

    1984-01-01

    Damage nucleation in single crystals of silicon during ion irradiation is investigated. Experimental results and mechanisms for damage nucleation during both room and liquid nitrogen temperature irradiation with different mass ions are discussed. It is shown that the accumulation of damage during room temperature irradiation depends on the rate of implantation. These dose rate effects are found to decrease in magnitude as the mass of the ions is increased. The significance of dose rate effects and their mass dependence on nucleation mechanisms is discussed

  6. Controlled nucleation and crystallization of fluorozirconate glasses

    International Nuclear Information System (INIS)

    Frischat, G.H.

    1993-01-01

    Pt, Se, and Ag, respectively, were used as nucleating agents for a ZrF 4 -BaF 4 -YF 3 -AlF 3 glass. Nucleation and crystal growth rates were determined as a function of experimental conditions. In all cases the bulk crystals mainly consist of β-BaZrF6, leading to a relatively coarse-grained microstructure. However, in the case of Ag used as a nucleating agent, the microstructure is bimodal with an additional fine-grained crystal phase. In the cases of Se and Ag the relative crystal fraction could be developed in a controlled way between 0 and 100%

  7. Viscosity of interfacial water regulates ice nucleation

    International Nuclear Information System (INIS)

    Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan; Xu, Shun; Zhou, Xin; Cui, Dapeng; Wang, Jianjun; Song, Yanlin

    2014-01-01

    Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J 0 and Γ, in the context of classical nucleation theory. From the extracted J 0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces

  8. Nanowires and nanoneedles nucleation on vicinal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xu, E-mail: zhangxubetter@gmail.com [Henan Key Laboratory of Laser and Opto-electric Information Technology, School of Information Engineering, Zhengzhou University, Zhengzhou 450052 (China); Xie, Dan; Huang, Genling [Zhengzhou Railway Vocational and Technical College, Zhengzhou 450052 (China); Sun, Xiao-Hong [Henan Key Laboratory of Laser and Opto-electric Information Technology, School of Information Engineering, Zhengzhou University, Zhengzhou 450052 (China)

    2015-01-01

    An analytic stress-driven nucleation model of nanowires (NWs) and nanoneedles (NNs) growing on a mismatched vicinal substrate is proposed. It is demonstrated that the formation enthalpy of NWs and NNs is a function of three independent variables, the base radius, aspect ratio and miscut angle of the vicinal surface. Theoretical analysis shows that the minimum nucleation barrier of an island decreases with increment of substrate misorientation, which means the nucleation of islands on a vicinal substrate is more favorable than that on a flat substrate.

  9. Recovery Profiles of T-Cell Subsets Following Low-Dose Total Body Irradiation and Improvement With Cinnamon

    International Nuclear Information System (INIS)

    Zheng, Xiaodan; Guo, Yuqi; Wang, Lei; Zhang, Honghai; Wang, Shaobo; Wang, Li; An, Lei; Zhou, Xianbin; Li, Xia; Yao, Chengfang

    2015-01-01

    Purpose: Inefficient T-cell reconstitution from x-ray–induced immune damage reduces antitumor response. To understand the profile of T-cell reconstitution after irradiation will overcome the barrier of antitumor immunity. This study aimed to identify the recovery profile of T-cell subsets following x-ray irradiation and to highlight the role of cinnamon on efficient T-cell restoration postexposure in the antitumor response. Methods and Materials: CD3"+, CD8"+, and CD4"+ T cells and Th1, Th2, Th17, and regulatory T (Treg) cells were evaluated at different time points after single low-dose total body irradiation (SLTBI) with or without cinnamon treatments. T-bet, GATA3, RORγt, and Foxp3 signaling specific for Th1, Th2, Th17, and Treg were also analyzed by RT-PCR assay. The effects of cinnamon on efficient T-cell subset reconstitution was confirmed in a lung melanoma model in irradiated mice. Results: Reconstitution of CD4"+ T cells was delayed more than that of CD8"+ T cells in T-cell restoration after SLTBI. The production of IFNγ by Th1 or Tc1 cells was sharply decreased and was accompanied by reduced T-bet mRNA, even when total T-cell numbers had recovered; the frequencies of Th17 and Treg cells and their specific transcription factors (RORγt and Foxp3, respectively) were obviously increased. Irradiation-induced inefficient T-cell reconstitution impaired the antitumor capacities in the lung melanoma model. Pretreatment with cinnamon in irradiated mice accelerated the generation of Th1 and reduced the differentiation of Treg cells by activating T-bet and limiting transcriptions of Foxp3. Improvement resulting from cinnamon pretreatment on the efficient T-cell recovery profile from SLTBI promoted antitumor immunity in the lung melanoma model. Conclusions: T-cell reconstitution from SLTBI was characterized by impaired Th1 and elevated Th17 and Treg cells. Cinnamon effectively improved the imbalance of T-cell subsets by promoting the proliferation of Th1 and

  10. Recovery Profiles of T-Cell Subsets Following Low-Dose Total Body Irradiation and Improvement With Cinnamon

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Xiaodan [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); School of Medicine and Life Science, University of Jinan-Shandong Academy of Medical Science, Jinan (China); Guo, Yuqi [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); Wang, Lei [Second Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan (China); Zhang, Honghai [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); Wang, Shaobo [Shandong University, Jinan (China); Wang, Li [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); An, Lei [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); School of Medicine and Life Science, University of Jinan-Shandong Academy of Medical Science, Jinan (China); Zhou, Xianbin; Li, Xia [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China); Yao, Chengfang, E-mail: yaocf9941@163.com [Key Laboratory for Tumor Immunology and Traditional Chinese Medicine Immunology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan (China)

    2015-12-01

    Purpose: Inefficient T-cell reconstitution from x-ray–induced immune damage reduces antitumor response. To understand the profile of T-cell reconstitution after irradiation will overcome the barrier of antitumor immunity. This study aimed to identify the recovery profile of T-cell subsets following x-ray irradiation and to highlight the role of cinnamon on efficient T-cell restoration postexposure in the antitumor response. Methods and Materials: CD3{sup +}, CD8{sup +}, and CD4{sup +} T cells and Th1, Th2, Th17, and regulatory T (Treg) cells were evaluated at different time points after single low-dose total body irradiation (SLTBI) with or without cinnamon treatments. T-bet, GATA3, RORγt, and Foxp3 signaling specific for Th1, Th2, Th17, and Treg were also analyzed by RT-PCR assay. The effects of cinnamon on efficient T-cell subset reconstitution was confirmed in a lung melanoma model in irradiated mice. Results: Reconstitution of CD4{sup +} T cells was delayed more than that of CD8{sup +} T cells in T-cell restoration after SLTBI. The production of IFNγ by Th1 or Tc1 cells was sharply decreased and was accompanied by reduced T-bet mRNA, even when total T-cell numbers had recovered; the frequencies of Th17 and Treg cells and their specific transcription factors (RORγt and Foxp3, respectively) were obviously increased. Irradiation-induced inefficient T-cell reconstitution impaired the antitumor capacities in the lung melanoma model. Pretreatment with cinnamon in irradiated mice accelerated the generation of Th1 and reduced the differentiation of Treg cells by activating T-bet and limiting transcriptions of Foxp3. Improvement resulting from cinnamon pretreatment on the efficient T-cell recovery profile from SLTBI promoted antitumor immunity in the lung melanoma model. Conclusions: T-cell reconstitution from SLTBI was characterized by impaired Th1 and elevated Th17 and Treg cells. Cinnamon effectively improved the imbalance of T-cell subsets by promoting the

  11. The effect of whole body or total-head x irradiation of the metallophilic cells in the mice spleen

    International Nuclear Information System (INIS)

    Sasaki, Osamu; Matsueda, Yasutoshi; Mizuguchi, Hiroshi; Moriguchi, Kenzo; Ogata, Kunitoshi; Sugie, Tsuneto

    1984-01-01

    The purpose of this paper is to clarify morphological changes of the reticuloendothelial cells in the spleen following X-irradiation by Katsura's silver impregnation method. The animals used in this experiment were ddN female mice weighing 20 to 25g. The mice were given X-irradiation to the total-head (1,500R) or whole body (300R). The metallophilic cells in the spleen of control mice were of the small foamy type in the follicle, the large stellate type in the marginal metallophils, the small branching type in the marginal zone and the small foamy or round type in the red pulp, respectively. The metallophilic cells decreased immediately after whole body irradiation and the number of cells returned to normal in from 10 to 14 days. On the other hand, the number of the metallophilic cells in the follicle and the perifollicular region increased immediately after total-head X-irradiation. This state continued for several days. In the marginal zone and red pulp, the number of amoebian type cells appeared from 24 hours after irradiation and the number of cells in total-head irradiation group were more clearly distinguishable than in the whole body irradiated group. (author)

  12. Dose-escalated total body irradiation and autologous stem cell transplantation for refractory hematologic malignancy

    International Nuclear Information System (INIS)

    McAfee, Steven L.; Powell, Simon N.; Colby, Christine; Spitzer, Thomas R.

    2002-01-01

    Purpose: To evaluate the feasibility of dose escalation of total body irradiation (TBI) above the previously reported maximally tolerated dose, we have undertaken a Phase I-II trial of dose-escalated TBI with autologous peripheral blood stem cell transplantation (PBSCT) for chemotherapy-refractory lymphoma. Methods and Materials: Nine lymphoma patients with primary refractory disease (PRD) or in resistant relapse (RR) received dose-escalated TBI and PBSCT. The three dose levels of fractionated TBI (200 cGy twice daily) were 1,600 cGy, 1,800 cGy, and 2,000 cGy. Lung blocks were used to reduce the TBI transmission dose by 50%, and the chest wall dose was supplemented to the prescribed dose using electrons. Shielding of the kidneys was performed to keep the maximal renal dose at 1,600 cGy. Three patients, two with non-Hodgkin's lymphoma (NHL) in RR and one with PRD Hodgkin's disease, received 1,600 cGy + PBSCT, three patients (two NHL in RR, one PRD) received 1,800 cGy + PBSCT, and three patients with NHL (two in RR, one PRD) received 2,000 cGy + PBSCT. Results: Toxicities associated with this high-dose TBI regimen included reversible hepatic veno-occlusive disease in 1 patient, Grade 2 mucositis requiring narcotic analgesics in 8 patients, and neurologic toxicities consisting of a symmetrical sensory neuropathy (n=4) and Lhermitte's syndrome (n=1). Interstitial pneumonitis developed in 1 patient who received 1,800 cGy after receiving recombinant α-interferon (with exacerbation after rechallenge with interferon). Six (66%) patients achieved a response. Four (44%) patients achieved complete responses, three of which were of a duration greater than 1 year, and 2 (22%) patients achieved a partial response. One patient remains disease-free more than 5 years posttransplant. Corticosteroid-induced gastritis and postoperative infection resulted in the death of 1 patient in complete response, 429 days posttransplant. Conclusion: TBI in a dose range 1,600-2,000 cGy as

  13. Observation and Analysis of Particle Nucleation at a Forest Site in Southeastern US

    Directory of Open Access Journals (Sweden)

    Viney Aneja

    2013-04-01

    Full Text Available This study examines the characteristics of new particle formation at a forest site in southeastern US. Particle size distributions above a Loblolly pine plantation were measured between November 2005 and September 2007 and analyzed by event type and frequency, as well as in relation to meteorological and atmospheric chemical conditions. Nucleation events occurred on 69% of classifiable observation days. Nucleation frequency was highest in spring. The highest daily nucleation (class A and B events frequency (81% was observed in April. The average total particle number concentration on nucleation days was 8,684 cm−3 (10 < Dp < 250 nm and 3,991 cm−3 (10 < Dp < 25 nm with a mode diameter of 28 nm with corresponding values on non-nucleation days of 2,143 cm−3, 655 cm−3, and 44.5 nm, respectively. The annual average growth rate during nucleation events was 2.7 ± 0.3 nm·h−1. Higher growth rates were observed during summer months with highest rates observed in May (5.0 ± 3.6 nm·h−1. Winter months were associated with lower growth rates, the lowest occurring in February (1.2 ± 2.2 nm·h−1. Consistent with other studies, nucleation events were more likely to occur on days with higher radiative flux and lower relative humidity compared to non-nucleation days. The daily minimum in the condensation sink, which typically occurred 2 to 3 h after sunrise, was a good indicator of the timing of nucleation onset. The intensity of the event, indicated by the total particle number concentration, was well correlated with photo-synthetically active radiation, used here as a surrogate for total global radiation, and relative humidity. Even though the role of biogenic VOC in the initial nuclei formation is not understood from this study, the relationships with chemical precursors and secondary aerosol products associated with nucleation, coupled with diurnal boundary layer dynamics and seasonal meteorological patterns, suggest that H2SO4 and biogenic

  14. The Effects of Cell Phone Waves (900 MHz-GSM Band) on Sperm Parameters and Total Antioxidant Capacity in Rats.

    Science.gov (United States)

    Ghanbari, Masoud; Mortazavi, Seyed Bagher; Khavanin, Ali; Khazaei, Mozafar

    2013-04-01

    There is tremendous concern regarding the possible adverse effects of cell phone microwaves. Contradictory results, however, have been reported for the effects of these waves on the body. In the present study, the effect of cell phone microwaves on sperm parameters and total antioxidant capacity was investigated with regard to the duration of exposure and the frequency of these waves. This experimental study was performed on 28 adult male Wistar rats (200-250 g). The animals were randomly assigned to four groups (n=7): i. control; ii. two-week exposure to cell phone-simulated waves; iii. three-week exposure to cell phonesimulated waves; and iv. two-week exposure to cell phone antenna waves. In all groups, sperm analysis was performed based on standard methods and we determined the mean sperm total antioxidant capacity according to the ferric reducing ability of plasma (FRAP) method. Data were analyzed by one-way ANOVA followed by Tukey's test using SPSS version 16 software. The results indicated that sperm viability, motility, and total antioxidant capacity in all exposure groups decreased significantly compared to the control group (pcell phone waves can decrease sperm viability and motility in rats. These waves can also decrease sperm total antioxidant capacity in rats and result in oxidative stress.

  15. The Effects of Cell Phone Waves (900 MHz-GSM Band on Sperm Parameters and Total Antioxidant Capacity in Rats

    Directory of Open Access Journals (Sweden)

    Masoud Ghanbari

    2013-01-01

    Full Text Available Background: There is tremendous concern regarding the possible adverse effects of cellphone microwaves. Contradictory results, however, have been reported for the effectsof these waves on the body. In the present study, the effect of cell phone microwaves onsperm parameters and total antioxidant capacity was investigated with regard to the durationof exposure and the frequency of these waves.Materials and Methods: This experimental study was performed on 28 adult male Wistarrats (200-250 g. The animals were randomly assigned to four groups (n=7: i. control; ii.two-week exposure to cell phone-simulated waves; iii. three-week exposure to cell phonesimulatedwaves; and iv. two-week exposure to cell phone antenna waves. In all groups,sperm analysis was performed based on standard methods and we determined the meansperm total antioxidant capacity according to the ferric reducing ability of plasma (FRAPmethod. Data were analyzed by one-way ANOVA followed by Tukey’s test using SPSSversion 16 software.Results: The results indicated that sperm viability, motility, and total antioxidant capacityin all exposure groups decreased significantly compared to the control group (p<0.05.Increasing the duration of exposure from 2 to 3 weeks caused a statistically significantdecrease in sperm viability and motility (p<0.05.Conclusion: Exposure to cell phone waves can decrease sperm viability and motility inrats. These waves can also decrease sperm total antioxidant capacity in rats and result inoxidative stress.

  16. Recovery of rat lens epithelial cells after total or partial x-irradiation

    International Nuclear Information System (INIS)

    Miller, R.C.; Riley, E.F.

    1987-01-01

    Irradiation of whole lenses interferes with the normal mitogenic response of lens cells to stimulation by mechanical wounding. Radiation exposure causes a delay and partial suppression of cells entering the S phase of the cell cycle. When cells are irradiated 1 day before wounding, DNA synthesis begins 20 hr after wounding and peaks 10 hr later. The return to a normal wound response is gradual when the time interval between irradiation and wounding is lengthened. By 28 days, essentially complete recovery of the wound response occurs. Mitosis shows a similar pattern of recovery. When half of the lens is irradiated 1 day before wounding, delay and suppression of the wound response in the irradiated half of the lens epithelium is observed. However, if 4 days elapse between irradiation and mechanical wounding, complete recovery of cells responding to the mitogenic stimulus occurs. Cells of the shielded half of the lens appear to compensate for the reduced number of irradiated cells entering S phase so that peak labelling of shielded cells is 70% compared with 50% for control lens cells. An evaluation of mitotic figures confirms faster recovery of the entire lens when only half the lens is irradiated. Complete recovery of the cellular response of partially irradiated lenses occurs in 4 days in contrast to almost 28 days for wholly irradiated lenses. (author)

  17. Long-Term Effects of Stem Cells on Total-Body Irradiated Mice

    Science.gov (United States)

    Vyalkina, M. V.; Alchinova, I. B.; Yakovenko, E. N.; Medvedeva, Yu S.; Saburina, I. N.; Karganov, M. Yu

    2017-01-01

    C57Bl/6 mice were exposed to γ-radiation in a sublethal dose of 7.5 Gy. In 3 hours injection 106/mouse of bone marrow multipotent mesenchymal stromal cells stem cells intravenously to experimental group was done. Methods used: body weight measurement, open field behavior, subfraction composition of blood serum (laser correlation spectroscopy, LCS), histological examination of the spleen, liver, and pancreas, count of T and B cells, white blood formula. After 1.5 and 3 months the general trend towards intermediate position of the parameters observed in the experimental between those in intact and irradiated controls attests to partial protective/restorative effects of the injected cells.

  18. Allometric relations of total volumes of prolactin cells and corticotropic cells to body length in the annual cyprinodont Cynolebias whitei: effects of environmental salinity, stress and ageing

    NARCIS (Netherlands)

    Ruijter, J. M.; Wendelaar Bonga, S. E.

    1987-01-01

    An analysis of the allometric relations of the total volumes occupied by prolactin (PRL) and corticotropic (ACTH) cells (PRL volume and ACTH volume, respectively) to body length and a study of the immunocytochemical staining intensity of PRL and ACTH cells were used to determine the differences in

  19. Functional display of ice nucleation protein InaZ on the surface of bacterial ghosts.

    Science.gov (United States)

    Kassmannhuber, Johannes; Rauscher, Mascha; Schöner, Lea; Witte, Angela; Lubitz, Werner

    2017-09-03

    In a concept study the ability to induce heterogeneous ice formation by Bacterial Ghosts (BGs) from Escherichia coli carrying ice nucleation protein InaZ from Pseudomonas syringae in their outer membrane was investigated by a droplet-freezing assay of ultra-pure water. As determined by the median freezing temperature and cumulative ice nucleation spectra it could be demonstrated that both the living recombinant E. coli and their corresponding BGs functionally display InaZ on their surface. Under the production conditions chosen both samples belong to type II ice-nucleation particles inducing ice formation at a temperature range of between -5.6 °C and -6.7 °C, respectively. One advantage for the application of such BGs over their living recombinant mother bacteria is that they are non-living native cell envelopes retaining the biophysical properties of ice nucleation and do no longer represent genetically modified organisms (GMOs).

  20. Energetics of dislocation nucleation under a nanoindenter

    International Nuclear Information System (INIS)

    Zhang Chuanli; Xu Guanshui

    2005-01-01

    We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip

  1. Energetics of dislocation nucleation under a nanoindenter

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Chuanli [College of Mechanical Engineering, Yangtze University, Jingzhou, Hubei 434023 (China); Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States); Xu Guanshui [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States)]. E-mail: guanshui.xu@ucr.edu

    2005-07-25

    We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip.

  2. Resveratrol combined with total flavones of hawthorn alleviate the endothelial cells injury after coronary bypass graft surgery.

    Science.gov (United States)

    Zhu, Ying; Feng, Bing; He, Songmin; Su, Zuqing; Zheng, Guangjuan

    2018-02-01

    To explore the preventive and therapeutic effects of Resveratrol combined with total flavones of hawthorn, compatibility of traditional Chinese medicines, on the endothelial cells injury after artery bypass graft surgery. The animal model of coronary artery bypass grafting (CABG) was prepared by transplanting a segment of autologous jugular vein onto the transected common carotid artery in rabbits. After CABG surgery, the rabbits were administrated with saline (model group), aspirin (Aspirin group), resveratrol (Res group), total flavones of hawthorn (Haw group) and resveratrol combined with total flavones of hawthorn (Res+Haw group) once a day for eight weeks, respectively. Eight weeks later, the grafting arteries from all group were obtained for the pathomorphism observation, peripheral blood was collected to detect circulating endothelial cells (CECs) by flow cytometry. And the concentration of albumen and mRNA of ICAM-1 in the serum were measured by western blot and quantitative real-time polymerase chain reaction, respectively. Compared with the model group, the level of CECs density and the expressions of albumen and mRNA of ICAM-1 were significantly decreased in the aspirin,resveratrol,total flavones of hawthorn and resveratrol combined with total flavones of hawthorn groups (P Resveratrol combined with total flavones of hawthorn could protect the endothelial cells after coronary artery bypass graft. Copyright © 2018 Elsevier GmbH. All rights reserved.

  3. Exploring the relationship of peripheral total bilirubin, red blood cell, and hemoglobin with blood pressure during childhood and adolescence.

    Science.gov (United States)

    Chen, Xiao-Tian; Yang, Song; Yang, Ya-Ming; Zhao, Hai-Long; Chen, Yan-Chun; Zhao, Xiang-Hai; Wen, Jin-Bo; Tian, Yuan-Rui; Yan, Wei-Li; Shen, Chong

    2017-11-04

    Total bilirubin is beneficial for protecting cardiovascular diseases in adults. The authors aimed to investigate the association of total bilirubin, red blood cell, and hemoglobin levels with the prevalence of high blood pressure in children and adolescents. A total of 3776 students (aged from 6 to 16 years old) were examined using cluster sampling. Pre-high blood pressure and high blood pressure were respectively defined as the point of 90th and 95th percentiles based on the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Both systolic and diastolic blood pressure were standardized into z-scores. Peripheral total bilirubin, red blood cell and hemoglobin levels were significantly correlated with age, and also varied with gender. Peripheral total bilirubin was negatively correlated with systolic blood pressure in 6- and 9-year-old boys, whilst positively correlated with diastolic blood pressure in the 12-year-old boys and 13- to 15-year-old girls (p0.05). Total bilirubin could be weakly correlated with both systolic and diastolic blood pressure, as correlations varied with age and gender in children and adolescents; in turn, the increased levels of red blood cell and hemoglobin are proposed to be positively associated with the prevalence of high blood pressure. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  4. A clinical audit of the utilisation of red cell products in elective total ...

    African Journals Online (AJOL)

    in elective total hip replacement surgery. Y G Peters,1,2 MTech; A R ... Background. Previous studies have documented a marked variation in transfusion practice for total hip replacement (THR) surgery. Objective. ..... European Overview (OSTHEO) Study: Blood management in elective knee and hip arthroplasty in. Europe.

  5. Massachusetts Fuel Cell Bus Project: Demonstrating a Total Transit Solution for Fuel Cell Electric Buses in Boston

    Energy Technology Data Exchange (ETDEWEB)

    2017-05-22

    The Federal Transit Administration's National Fuel Cell Bus Program focuses on developing commercially viable fuel cell bus technologies. Nuvera is leading the Massachusetts Fuel Cell Bus project to demonstrate a complete transit solution for fuel cell electric buses that includes one bus and an on-site hydrogen generation station for the Massachusetts Bay Transportation Authority (MBTA). A team consisting of ElDorado National, BAE Systems, and Ballard Power Systems built the fuel cell electric bus, and Nuvera is providing its PowerTap on-site hydrogen generator to provide fuel for the bus.

  6. Stochastic simulation of nucleation in binary alloys

    Science.gov (United States)

    L’vov, P. E.; Svetukhin, V. V.

    2018-06-01

    In this study, we simulate nucleation in binary alloys with respect to thermal fluctuations of the alloy composition. The simulation is based on the Cahn–Hilliard–Cook equation. We have considered the influence of some fluctuation parameters (wave vector cutoff and noise amplitude) on the kinetics of nucleation and growth of minority phase precipitates. The obtained results are validated by the example of iron–chromium alloys.

  7. Grain nucleation and growth during phase transformations

    DEFF Research Database (Denmark)

    Offerman, S.E.; Dijk, N.H. van; Sietsma, J.

    2002-01-01

    of individual grains. Our measurements show that the activation energy for grain nucleation is at least two orders of magnitude smaller than that predicted by thermodynamic models. The observed growth curves of the newly formed grains confirm the parabolic growth model but also show three fundamentally...... different types of growth. Insight into the grain nucleation and growth mechanisms during phase transformations contributes to the development of materials with optimal mechanical properties....

  8. Nucleation versus instability race in strained films

    Science.gov (United States)

    Liu, Kailang; Berbezier, Isabelle; David, Thomas; Favre, Luc; Ronda, Antoine; Abbarchi, Marco; Voorhees, Peter; Aqua, Jean-Noël

    2017-10-01

    Under the generic term "Stranski-Krastanov" are grouped two different growth mechanisms of SiGe quantum dots. They result from the self-organized Asaro-Tiller-Grinfel'd (ATG) instability at low strain, while at high strain, from a stochastic nucleation. While these regimes are well known, we elucidate here the origin of the transition between these two pathways thanks to a joint theoretical and experimental work. Nucleation is described within the master equation framework. By comparing the time scales for ATG instability development and three-dimensional (3D) nucleation onset, we demonstrate that the transition between these two regimes is simply explained by the crossover between their divergent evolutions. Nucleation exhibits a strong exponential deviation at low strain while ATG behaves only algebraically. The associated time scale varies with exp(1 /x4) for nucleation, while it only behaves as 1 /x8 for the ATG instability. Consequently, at high (low) strain, nucleation (instability) occurs faster and inhibits the alternate evolution. It is then this different kinetic evolution which explains the transition from one regime to the other. Such a kinetic view of the transition between these two 3D growth regimes was not provided before. The crossover between nucleation and ATG instability is found to occur both experimentally and theoretically at a Ge composition around 50% in the experimental conditions used here. Varying the experimental conditions and/or the system parameters does not allow us to suppress the transition. This means that the SiGe quantum dots always grow via ATG instability at low strain and nucleation at high strain. This result is important for the self-organization of quantum dots.

  9. New mechanism for bubble nucleation: Classical transitions

    International Nuclear Information System (INIS)

    Easther, Richard; Giblin, John T. Jr; Hui Lam; Lim, Eugene A.

    2009-01-01

    Given a scalar field with metastable minima, bubbles nucleate quantum mechanically. When bubbles collide, energy stored in the bubble walls is converted into kinetic energy of the field. This kinetic energy can facilitate the classical nucleation of new bubbles in minima that lie below those of the 'parent' bubbles. This process is efficient and classical, and changes the dynamics and statistics of bubble formation in models with multiple vacua, relative to that derived from quantum tunneling.

  10. A classical view on nonclassical nucleation.

    Science.gov (United States)

    Smeets, Paul J M; Finney, Aaron R; Habraken, Wouter J E M; Nudelman, Fabio; Friedrich, Heiner; Laven, Jozua; De Yoreo, James J; Rodger, P Mark; Sommerdijk, Nico A J M

    2017-09-19

    Understanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO 3 ) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO 3 nucleation is still a topic of intense discussion, with new pathways for its growth from ions in solution proposed in recent years. These new pathways include the so-called nonclassical nucleation mechanism via the assembly of thermodynamically stable prenucleation clusters, as well as the formation of a dense liquid precursor phase via liquid-liquid phase separation. Here, we present results from a combined experimental and computational investigation on the precipitation of CaCO 3 in dilute aqueous solutions. We propose that a dense liquid phase (containing 4-7 H 2 O per CaCO 3 unit) forms in supersaturated solutions through the association of ions and ion pairs without significant participation of larger ion clusters. This liquid acts as the precursor for the formation of solid CaCO 3 in the form of vaterite, which grows via a net transfer of ions from solution according to z Ca 2+ + z CO 3 2- → z CaCO 3 The results show that all steps in this process can be explained according to classical concepts of crystal nucleation and growth, and that long-standing physical concepts of nucleation can describe multistep, multiphase growth mechanisms.

  11. Fractionated total body irradiation and autologous bone marrow transplantation in dogs: Hemopoietic recovery after various marrow cell doses

    International Nuclear Information System (INIS)

    Bodenburger, U.; Kolb, H.J.; Thierfelder, S.; Netzel, B.; Schaeffer, E.; Kolb, H.

    1980-01-01

    Hemopoietic recovery was studied in dogs given 2400 R fractionated total body irradiation within one week and graded doses of cryopreserved autologous bone marrow. Complete hemopoietic recovery including histology was observed after this dose and sufficient doses of marrow cells. Doses of more than 5.5 x 10 7 mononuclear marrow cells/kg body weight were sufficient for complete recovery in all dogs, 1.5 to 5.5 x 10 7 cells/kg were effective in some of the dogs and less than 1.5 x 10 7 cells/kg were insufficient for complete recovery. Similarly, more than 30000 CFUsub(c)/kg body weight were required for hemopoietic recovery. The optimal marrow cell dose which has been defined as the minimal dose required for the earliest possible recovery of leukocyte and platelet counts was 7-8 x 10 7 mononuclear marrow cells/kg body weight. It has been concluded that fractionated total body irradiation with 2400 R dose not require greater doses of marrow cells for hemopoietic reconstitution than lower single doses and that the hemopoietic microenvironment is not persistently disturbed after this dose. (author)

  12. Total white blood cell counts and LPS-induced TNF alpha production by monocytes of pregnant, pseudopregnant and cyclic rats

    NARCIS (Netherlands)

    Faas, MM; Moes, H; van der Schaaf, G; de Leij, LFMH; Heineman, MJ

    Pregnancy in the rat may be associated with an activated innate immune system. Therefore, we investigated monocyte function as well as total white blood cell (WBC) counts during the follicular phase of the ovarian cycle, pregnancy and pseudopregnancy in the rat. Rats were equipped with a permanent

  13. Total white blood cell counts and LPS-induced TNF alpha production by monocytes of pregnant, pseudopregnant and cyclic rats

    NARCIS (Netherlands)

    Faas, M. M.; Moes, H.; van der Schaaf, G.; de Leij, L. F. M. H.; Heineman, M. J.

    2003-01-01

    Pregnancy in the rat may be associated with an activated innate immune system. Therefore, we investigated monocyte function as well as total white blood cell (WBC) counts during the follicular phase of the ovarian cycle, pregnancy and pseudopregnancy in the rat. Rats were equipped with a permanent

  14. Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

    Science.gov (United States)

    Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

  15. Total internal reflection fluorescence (TIRF) microscopy for real-time imaging of nanoparticle-cell plasma membrane interaction

    DEFF Research Database (Denmark)

    Parhamifar, Ladan; Moghimi, Seyed Moien

    2012-01-01

    Nanoparticulate systems are widely used for site-specific drug and gene delivery as well as for medical imaging. The mode of nanoparticle-cell interaction may have a significant effect on the pathway of nanoparticle internalization and subsequent intracellular trafficking. Total internal reflection...

  16. Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count

    NARCIS (Netherlands)

    Koop, G.; Dik, N.; Nielen, M.; Lipman, L.J.A.

    2010-01-01

    The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms,

  17. Flow cytometry total cell counts : A field study assessing microbiological water quality and growth in unchlorinated drinking water distribution systems

    NARCIS (Netherlands)

    Liu, G.; Van der Mark, E.J.; Verberk, J.Q.; Van Dijk, J.C.

    2013-01-01

    e objective of this study was to evaluate the application of flow cytometry total cell counts (TCCs) as a parameter to assess microbial growth in drinking water distribution systems and to determine the relationships between different parameters describing the biostability of treated water. A

  18. Long-Term Effects of Stem Cells on Total-Body Irradiated Mice

    International Nuclear Information System (INIS)

    Vyalkina, M V; Alchinova, I B; Yakovenko, E N; Medvedeva, Yu S; Saburina, I N; Karganov, M Yu

    2017-01-01

    C57Bl/6 mice were exposed to γ-radiation in a sublethal dose of 7.5 Gy. In 3 hours injection 10 6 /mouse of bone marrow multipotent mesenchymal stromal cells stem cells intravenously to experimental group was done. Methods used: body weight measurement, open field behavior, subfraction composition of blood serum (laser correlation spectroscopy, LCS), histological examination of the spleen, liver, and pancreas, count of T and B cells, white blood formula. After 1.5 and 3 months the general trend towards intermediate position of the parameters observed in the experimental between those in intact and irradiated controls attests to partial protective/restorative effects of the injected cells. (paper)

  19. Convergent evolution of germ granule nucleators: A hypothesis.

    Science.gov (United States)

    Kulkarni, Arpita; Extavour, Cassandra G

    2017-10-01

    Germ cells have been considered "the ultimate stem cell" because they alone, during normal development of sexually reproducing organisms, are able to give rise to all organismal cell types. Morphological descriptions of a specialized cytoplasm termed 'germ plasm' and associated electron dense ribonucleoprotein (RNP) structures called 'germ granules' within germ cells date back as early as the 1800s. Both germ plasm and germ granules are implicated in germ line specification across metazoans. However, at a molecular level, little is currently understood about the molecular mechanisms that assemble these entities in germ cells. The discovery that in some animals, the gene products of a small number of lineage-specific genes initiate the assembly (also termed nucleation) of germ granules and/or germ plasm is the first step towards facilitating a better understanding of these complex biological processes. Here, we draw on research spanning over 100years that supports the hypothesis that these nucleator genes may have evolved convergently, allowing them to perform analogous roles across animal lineages. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Molecular nucleation mechanisms and control strategies for crystal polymorph selection

    Science.gov (United States)

    van Driessche, Alexander E. S.; van Gerven, Nani; Bomans, Paul H. H.; Joosten, Rick R. M.; Friedrich, Heiner; Gil-Carton, David; Sommerdijk, Nico A. J. M.; Sleutel, Mike

    2018-04-01

    The formation of condensed (compacted) protein phases is associated with a wide range of human disorders, such as eye cataracts, amyotrophic lateral sclerosis, sickle cell anaemia and Alzheimer’s disease. However, condensed protein phases have their uses: as crystals, they are harnessed by structural biologists to elucidate protein structures, or are used as delivery vehicles for pharmaceutical applications. The physiochemical properties of crystals can vary substantially between different forms or structures (‘polymorphs’) of the same macromolecule, and dictate their usability in a scientific or industrial context. To gain control over an emerging polymorph, one needs a molecular-level understanding of the pathways that lead to the various macroscopic states and of the mechanisms that govern pathway selection. However, it is still not clear how the embryonic seeds of a macromolecular phase are formed, or how these nuclei affect polymorph selection. Here we use time-resolved cryo-transmission electron microscopy to image the nucleation of crystals of the protein glucose isomerase, and to uncover at molecular resolution the nucleation pathways that lead to two crystalline states and one gelled state. We show that polymorph selection takes place at the earliest stages of structure formation and is based on specific building blocks for each space group. Moreover, we demonstrate control over the system by selectively forming desired polymorphs through site-directed mutagenesis, specifically tuning intermolecular bonding or gel seeding. Our results differ from the present picture of protein nucleation, in that we do not identify a metastable dense liquid as the precursor to the crystalline state. Rather, we observe nucleation events that are driven by oriented attachments between subcritical clusters that already exhibit a degree of crystallinity. These insights suggest ways of controlling macromolecular phase transitions, aiding the development of protein

  1. Treatment of Renal Cell Carcinoma with 2-Stage Total en bloc Spondylectomy after Marked Response to Molecular Target Drugs

    Directory of Open Access Journals (Sweden)

    Yasuhiro Inoue

    2013-01-01

    Full Text Available Metastatic renal cell carcinoma of the bone occurs at a high rate, and the prognosis is poor. In general, total en bloc spondylectomy is considered when there is only one vertebral metastasis and the primary disease is treated. However, palliative surgery is selected when the primary disease is not being treated or metastasis occurs to an important organ. We encountered a patient in whom lung and vertebra metastases were already present at the time of the first examination at our department and the prognosis was considered poor. However, molecular targeted therapy was markedly effective and enabled 2-stage total en bloc spondylectomy. As of one year after total en bloc spondylectomy, the condition has improved to cane gait, and surgery for lung metastasis is planned. Molecular target drugs might markedly change the current therapeutic strategy for renal cell carcinoma.

  2. Total Alkaloids of Sophora alopecuroides Inhibit Growth and Induce Apoptosis in Human Cervical Tumor HeLa Cells In vitro.

    Science.gov (United States)

    Li, Jian-Guang; Yang, Xiao-Yi; Huang, Wei

    2016-05-01

    Uygur females of Xinjiang have the higher incidence of cervical tumor in the country. Alkaloids are the major active ingredients in Sophora alopecuroides, and its antitumor effect was recognized by the medical profession. Xinjiang is the main site of S. alopecuroides production in China so these plants are abundant in the region. Studies on the antitumor properties of total alkaloids of S. alopecuroides (TASA) can take full use of the traditional folk medicine in antitumor unique utility. To explore the effects of TASA on proliferation and apoptosis of human cervical tumor HeLa cells in vitro. TASA was extracted, purified, and each monomer component was analyzed by high-performance liquid chromatography. The effect of TASA at different concentrations on the survival of HeLa cells was determined after 24 h using the Cell Counting Kit-8. In addition, cells were photographed using an inverted microscope to document morphological changes. The effect of TASA on apoptotic rate of HeLa cells was assessed by flow cytometry. Monomers of TASA were found to be sophoridine, matrine, and sophocarpine. On treatment with 8.75 mg/ml of TASA, more than 50% of HeLa cells died, and cell death rate increased further with longer incubation. The apoptotic rates of HeLa cells in the experimental groups were 16.0% and 33.3% at concentrations of 6.25 mg/ml and 12.50 mg/ml, respectively. TASA can induce apoptosis in cervical tumor HeLa cells, and it has obvious inhibitory effects on cell growth. Total alkaloids of Sophora alopecuroides (TASA) exhibits anti-human cervical tumor propertiesMonomer component of TASA was analyzed by high-performance liquid chromatography, and its main effect component are sophoridine, matrine, and sophocarpineTASA inhibits growth and induces apoptosis in HeLa cells. Abbreviations used: TASA: Total alkaloids of S. alopecuroides, CCK-8: Cell Counting Kit-8, FBS: Fetal bovine serum, PBS: Phosphate buffered saline, DMEM: Dulbecco's modified Eagle medium.

  3. Hybrid fuel cell/diesel generation total energy system, part 2

    Science.gov (United States)

    Blazek, C. F.

    1982-11-01

    Meeting the Goldstone Deep Space Communications Complex (DGSCC) electrical and thermal requirements with the existing system was compared with using fuel cells. Fuel cell technology selection was based on a 1985 time frame for installation. The most cost-effective fuel feedstock for fuel cell application was identified. Fuels considered included diesel oil, natural gas, methanol and coal. These fuel feedstocks were considered not only on the cost and efficiency of the fuel conversion process, but also on complexity and integration of the fuel processor on system operation and thermal energy availability. After a review of fuel processor technology, catalytic steam reformer technology was selected based on the ease of integration and the economics of hydrogen production. The phosphoric acid fuel cell was selected for application at the GDSCC due to its commercial readiness for near term application. Fuel cell systems were analyzed for both natural gas and methanol feedstock. The subsequent economic analysis indicated that a natural gas fueled system was the most cost effective of the cases analyzed.

  4. Cell biological effects of total body irradiation on growth and differentiation of acute myelogenous leukemia cells compared to normal bone marrow

    Energy Technology Data Exchange (ETDEWEB)

    Greenberger, J S; Weichselbaum, R R; Botnick, L E; Sakakeeny, M; Moloney, W C

    1979-01-01

    Radiation therapy is used as total body treatment in preparation of the acute myelogenous leukemia (AML) patient for bone marrow transplantation. Many AML patients will have residual leukemia cells at the time of total body irradiation (TBI). In the present study, the effect of TBI on leukemic myeloid cells was compared to the effect on normal marrow granulocytic stem cells (CFUc) in vitro. Little difference from that of normal CFUc was found in the radiosensitivity of two mouse myeloid leukemia cell lines. The effect of TBI on growth of WEHI-3 or J774 cells in millipore diffusion chambers was stimulatory. These AML cell lines as well as others derived from Friend or Abelson virus infected in vitro long term mouse marrow cultures showed some morphologic differentiation by 7 days growth in diffusion chambers in irradiated heterologous rat hosts, but immature cells predominated by day 21. Thus, evidence in murine models of AML indicates that residual AML cells surviving chemotherapy will show no greater susceptibility to radiation killing compared to normal stem cells and will rapidly repopulate the irradiated host.

  5. Using rheometry for determining nucleation density in colored system containing a nucleation agent

    NARCIS (Netherlands)

    Ma, Z.; Steenbakkers, R.J.A.; Giboz, J.; Peters, G.W.M.

    2011-01-01

    A new suspension-based rheological method was applied to study experimentally the crystallization of a nucleating agent (NA) filled isotactic polypropylene. This method allows for determination of point-nucleation densities where other methods fail. For example, optical microscopy can fail because

  6. Controlled ice nucleation using freeze-dried Pseudomonas syringae encapsulated in alginate beads.

    Science.gov (United States)

    Weng, Lindong; Tessier, Shannon N; Swei, Anisa; Stott, Shannon L; Toner, Mehmet

    2017-04-01

    The control of ice nucleation is of fundamental significance in many process technologies related to food and pharmaceutical science and cryobiology. Mechanical perturbation, electromagnetic fields and ice-nucleating agents (INAs) have been known to induce ice nucleation in a controlled manner. But these ice-nucleating methods may suffer from cumbersome manual operations, safety concerns of external fields, and biocompatibility and recovery issues of INA particles, especially when used in living systems. Given the automatic ice-seeding nature of INAs, a promising solution to overcome some of the above limitations is to engineer a biocomposite that accommodates the INA particles but minimizes their interactions with biologics, as well as enabling the recovery of used particles. In this study, freeze-dried Pseudomonas syringae, a model ice-nucleating agent, was encapsulated into microliter-sized alginate beads. We evaluated the performance of the bacterial hydrogel beads to initiate ice nucleation in water and aqueous glycerol solution by investigating factors including the size and number of the beads and the local concentration of INA particles. In the aqueous sample of a fixed volume, the total mass of the INA particles (m) was found to be the governing parameter that is solely responsible for determining the ice nucleation performance of the bacterial hydrogel beads. The freezing temperature has a strong positive linear correlation with log 10 m. The findings in this study provide an effective, predictable approach to control ice nucleation, which can improve the outcome and standardization of many ice-assisted process technologies. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Stereological estimation of total cell numbers in the human cerebral and cerebellar cortex

    DEFF Research Database (Denmark)

    Walløe, Solveig; Pakkenberg, Bente; Fabricius, Katrine

    2014-01-01

    estimates and were often very time-consuming. Within the last 20-30 years, it has become possible to rely on more advanced and unbiased methods. These methods have provided us with information about fetal brain development, differences in cell numbers between men and women, the effect of age on selected...

  8. Radiobiological basis of total body irradiation with different dose rate and fractionation: repair capacity of hemopoietic cells

    International Nuclear Information System (INIS)

    Song, C.W.; Kim, T.H.; Khan, F.M.; Kersey, J.H.; Levitt, S.H.

    1981-01-01

    Total body irradiation (TBI) followed by bone marrow transplantation is being used in the treatment of malignant or non-malignant hemopoietic disorders. It has been believed that the ability of hemopoietic cells to repair sublethal radiation damage is negligible. Therefore, several schools of investigators suggested that TBI in a single exposure at extremely low dose rate (5 rad/min) over several hours, or in several fractions in 2-3 days, should yield a higher therapeutic gain, as compared with a single exposure at a high dose rate (26 rad/min). We reviewed the existing data in the literature, in particular, the response of hemopoietic cells to fractionated doses of irradiation and found that the repair capacity of both malignant and non-malignant hemopoietic cells might be greater than has been thought. It is concluded that we should not underestimate the ability of hemopoietic cells to repair sublethal radiation damage in using TBI

  9. Vapour–to–liquid nucleation: Nucleation theorems for nonisothermal–nonideal case

    Energy Technology Data Exchange (ETDEWEB)

    Malila, J.; McGraw, R.; Napari, I.; Laaksonen, A.

    2010-08-29

    Homogeneous vapour-to-liquid nucleation, a basic process of aerosol formation, is often considered as a type example of nucleation phenomena, while most treatment of the subject introduce several simplifying assumptions (ideal gas phase, incompressible nucleus, isothermal kinetics, size-independent surface free energy...). During last decades, nucleation theorems have provided new insights into properties of critical nuclei facilitating direct comparison between laboratory experiments and molecular simulations. These theorems are, despite of their generality, often applied in forms where the aforementioned assumptions are made. Here we present forms of nucleation theorems that explicitly take into account these effects and allow direct estimation of their importance. Only assumptions are Arrhenius-type kinetics of nucleation process and exclusion carrier gas molecules from the critical nucleus.

  10. Geometrical nuclear diagnosis and total paths of cervical cell evolution from normality to cancer

    Directory of Open Access Journals (Sweden)

    Javier Oswaldo Rodríguez Velásquez

    2015-01-01

    Full Text Available Background: The diagnosis of cervix cytology has problems of inter-observer reproducibility. Methodologies based on fractal geometry objectively differentiated normal, low-grade squamous intraepithelial lesion (L-SIL and high-grade squamous intraepithelial lesion (H-SIL states. Aims: The aim was to develop a mathematical-physical diagnosis and a theoretical generalization of the evolution paths of cervical cells from normal to carcinoma based on their occupation in the box-counting space. Subjects and Methods: Overlaying a grid of 8x8 pixels, the a number of squares occupying the nucleus surface and cytoplasm of 5 normal cells, 5 ASCUS, 5 L-SIL and 5 H-SIL were evaluated, as well as the ratio C/N, establishing differences between states. Sensitivity, specificity, negative likelihood ratio, and Kappa coefficient over the gold standard were calculated. Also was developed a generalization of all possible paths from normality to carcinoma. Results: The occupancy spaces of the nuclear surface allow differentiating normal L-SIL and H-SIL thus avoiding the indeterminacy of ASCUS cells. Compared to the Gold Standard, this method has sensitivity and specificity of 100%, negative likelihood ratio of 0, and Kappa coefficient of 1. 62,900 possible routes of evolution were determined between normal and H-SIL, states, based on the structural basis of the cells. Conclusions: it was obtained an objective and reproducible diagnostic methodology of the development of preneoplastic and neoplastic cervical cells for clinical application. Additionally were developed all possible paths of preneoplastic cellular alteration to carcinoma which facilitates the tracking of patients over time to clinical level, warning of alterations that lead to malignancy, based on the spatial occupation measurements of the nucleus in fractal space regardless of causes or risk factors.

  11. Measuring and modeling polymer concentration profiles near spindle boundaries argues that spindle microtubules regulate their own nucleation

    Science.gov (United States)

    Kaye, Bryan; Stiehl, Olivia; Foster, Peter J.; Shelley, Michael J.; Needleman, Daniel J.; Fürthauer, Sebastian

    2018-05-01

    Spindles are self-organized microtubule-based structures that segregate chromosomes during cell division. The mass of the spindle is controlled by the balance between microtubule turnover and nucleation. The mechanisms that control the spatial regulation of microtubule nucleation remain poorly understood. While previous work found that microtubule nucleators bind to pre-existing microtubules in the spindle, it is still unclear whether this binding regulates the activity of those nucleators. Here we use a combination of experiments and mathematical modeling to investigate this issue. We measured the concentration of microtubules and soluble tubulin in and around the spindle. We found a very sharp decay in the concentration of microtubules at the spindle interface. This is inconsistent with a model in which the activity of nucleators is independent of their association with microtubules but consistent with a model in which microtubule nucleators are only active when bound to pre-existing microtubules. This argues that the activity of microtubule nucleators is greatly enhanced when bound to pre-existing microtubules. Thus, microtubule nucleators are both localized and activated by the microtubules they generate.

  12. Mechanism of nucleation and growth of hydrogen porosity in solidifying A356 aluminum alloy: an analytical solution

    International Nuclear Information System (INIS)

    Li, K.-D.; Chang, Edward

    2004-01-01

    This study derives an analytical solution for the mechanism of nucleation and growth of hydrogen pore in the solidifying A356 aluminum alloy. A model of initial transient hydrogen redistribution in the growing dendritic grain is used to modify the lever rule for the mechanism of nucleation of pore. The model predicts the fraction of solid at nucleation, the temperature range of nucleation, the radius of hydrogen diffusion cell, and the supersaturation of hydrogen needed for nucleation. The role of solidus velocity in nucleation is explained. The parameters calculated from the model of nucleation are used for analyzing the mechanism of kinetic diffusion-controlled growth of pore, in which the mathematical transformations of variables are introduced. With the transformations, it is argued that the diffusion problem involving the liquid and solid phases during solidification could be treated as a classic problem of precipitation in the single-phase medium treated by Ham or Avrami. The analytical solution for the nucleation of pore is compared with the mechanism of macrosegregation. The predicted volume percent of porosity and radius of pore based on the mechanism of growth of pore is discussed with respect to the thermodynamic solution, the published experimental data, the numerical solutions, and the role of interdendritic fluid flow governed by Darcy's law

  13. Antiproliferative activity in tumor cell lines, antioxidant capacity and total phenolic, flavonoid and tannin contents of Myrciaria floribunda

    Directory of Open Access Journals (Sweden)

    LUIS A.C. TIETBOHL

    Full Text Available ABSTRACT Myrciaria floribunda (H. West ex Willd. O. Berg, Myrtaceae, is a native plant species of the Atlantic Rain Forest, from north to south of Brazil. The lyophilized ethyl acetate extract from the leaves of M. floribunda was investigated for its antiproliferative activity in tumor cell lines, antioxidant capacity and its total phenolic, flavonoid and tannin contents. Antiproliferative activity was tested in vitro against seven human cancer cells and against immortalized human skin keratinocytes line (HaCat, no cancer cell. Antioxidant activity was determined using 1-diphenyl-2-picrylhydrazyl (DPPH radical scavenging and oxygen radical absorbing capacity (ORAC assays and total phenolic, flavonoid and tannin contents were determined by spectrophotometric techniques. Ethyl acetate extract of M. floribunda exhibited antiproliferative activity against cancer cell lines with total growth inhibition (TGI between 69.70 and 172.10 µg/mL. For HaCat cell, TGI value was 213.60 µg/mL. M. floribunda showed a strong antioxidant potential: EC50 of 45.89±0.42 µg/mL and 0.55±0.05 mmol TE/g for DPPH and ORAC, respectively. Total phenolic content was 0.23±0.013g gallic acid equivalents (GAE/g extract and exhibited 13.10±1.60% of tannins content. The content of flavonoid was 24.08±0.44% expressed as rutin equivalents. These results provide a direction for further researches about the antitumoral potential of M. floribunda.

  14. Microtubule nucleation and organization in dendrites

    Science.gov (United States)

    Delandre, Caroline; Amikura, Reiko; Moore, Adrian W.

    2016-01-01

    ABSTRACT Dendrite branching is an essential process for building complex nervous systems. It determines the number, distribution and integration of inputs into a neuron, and is regulated to create the diverse dendrite arbor branching patterns characteristic of different neuron types. The microtubule cytoskeleton is critical to provide structure and exert force during dendrite branching. It also supports the functional requirements of dendrites, reflected by differential microtubule architectural organization between neuron types, illustrated here for sensory neurons. Both anterograde and retrograde microtubule polymerization occur within growing dendrites, and recent studies indicate that branching is enhanced by anterograde microtubule polymerization events in nascent branches. The polarities of microtubule polymerization events are regulated by the position and orientation of microtubule nucleation events in the dendrite arbor. Golgi outposts are a primary microtubule nucleation center in dendrites and share common nucleation machinery with the centrosome. In addition, pre-existing dendrite microtubules may act as nucleation sites. We discuss how balancing the activities of distinct nucleation machineries within the growing dendrite can alter microtubule polymerization polarity and dendrite branching, and how regulating this balance can generate neuron type-specific morphologies. PMID:27097122

  15. Modelling the stochastic behaviour of primary nucleation.

    Science.gov (United States)

    Maggioni, Giovanni Maria; Mazzotti, Marco

    2015-01-01

    We study the stochastic nature of primary nucleation and how it manifests itself in a crystallisation process at different scales and under different operating conditions. Such characteristics of nucleation are evident in many experiments where detection times of crystals are not identical, despite identical experimental conditions, but instead are distributed around an average value. While abundant experimental evidence has been reported in the literature, a clear theoretical understanding and an appropriate modelling of this feature is still missing. In this contribution, we present two models describing a batch cooling crystallisation, where the interplay between stochastic nucleation and deterministic crystal growth is described differently in each. The nucleation and growth rates of the two models are estimated by a comprehensive set of measurements of paracetamol crystallisation from aqueous solution in a 1 mL vessel [Kadam et al., Chemical Engineering Science, 2012, 72, 10-19]. Both models are applied to the cooling crystallisation process above under different operating conditions, i.e. different volumes, initial concentrations, cooling rates. The advantages and disadvantages of the two approaches are illustrated and discussed, with particular reference to their use across scales of nucleation rate measured in very small crystallisers.

  16. Ice nucleation rates near ˜225 K

    Science.gov (United States)

    Amaya, Andrew J.; Wyslouzil, Barbara E.

    2018-02-01

    We have measured the ice nucleation rates, Jice, in supercooled nano-droplets with radii ranging from 6.6 nm to 10 nm and droplet temperatures, Td, ranging from 225 K to 204 K. The initial temperature of the 10 nm water droplets is ˜250 K, i.e., well above the homogeneous nucleation temperature for micron sized water droplets, TH ˜235 K. The nucleation rates increase systematically from ˜1021 cm-3 s-1 to ˜1022 cm-3 s-1 in this temperature range, overlap with the nucleation rates of Manka et al. [Phys. Chem. Chem. Phys. 14, 4505 (2012)], and suggest that experiments with larger droplets would extrapolate smoothly the rates of Hagen et al. [J. Atmos. Sci. 38, 1236 (1981)]. The sharp corner in the rate data as temperature drops is, however, difficult to match with available theory even if we correct classical nucleation theory and the physical properties of water for the high internal pressure of the nanodroplets.

  17. Donor hematopoiesis in mice following total lymphoid irradiation requires host T-regulatory cells for durable engraftment

    Science.gov (United States)

    Müller, Antonia M. S.; Poyser, Jessica; Küpper, Natascha J.; Burnett, Cassandra; Ko, Rose M.; Kohrt, Holbrook E.K.; Florek, Mareike; Zhang, Pei; Negrin, Robert S.

    2014-01-01

    Total lymphoid irradiation (TLI) with antithymocyte globulin (ATG) is a unique regimen that prepares recipients for allogeneic hematopoietic cell transplantation by targeting lymph nodes, while sparing large areas of the bone marrow. TLI is reported to increase the frequency of CD4+CD25+FoxP3+ T-regulatory cells (Treg) relative to conventional T cells. In this study, barriers to hematopoietic stem cell (HSC) engraftment following this nonmyeloablative conditioning were evaluated. TLI/ATG resulted in profound lymphoablation but endogenous host HSC remained. Initial donor HSC engraftment occurred only in radiation exposed marrow sites, but gradually distributed to bone marrow outside the radiation field. Sustained donor engraftment required host lymphoid cells insofar as lymphocyte deficient Rag2γc−/− recipients had unstable engraftment compared with wild-type. TLI/ATG treated wild-type recipients had increased proportions of Treg that were associated with increased HSC frequency and proliferation. In contrast, Rag2γc−/− recipients who lacked Treg did not. Adoptive transfer of Treg into Rag2γc−/− recipients resulted in increased cell cycling of endogenous HSC. Thus, we hypothesize that Treg influence donor engraftment post-TLI/ATG by increasing HSC cell cycling, thereby promoting the exit of host HSC from the marrow niche. Our study highlights the unique dynamics of donor hematopoiesis following TLI/ATG, and the effect of Treg on HSC activity. PMID:24591203

  18. Efficiency and Cost Analysis of Cell Saver Auto Transfusion System in Total Knee Arthroplasty

    OpenAIRE

    Mustafa Gökhan Bilgili; Ersin Erçin; Cemal Kural; Altuğ Duramaz; Cevdet Avkan; Gökhan Peker; Serdar Hakan Başaran

    2014-01-01

    Background: Blood loss and replacement is still a controversial issue in major orthopaedic surgery. Allogenic blood transfusion may cause legal problems and concerns regarding the transmission of transfusion-related diseases. Cellsaver Systems (CSS) were developed as an alternative to allogenic transfusion but CSS transfusion may cause coagulation, infection and haemodynamic instability. Aims: Our aim was to analyse the efficiency and cost analysis of a cell saver auto-transfusion system ...

  19. Evaluation of velvet antler total protein effect on bone marrow-derived endothelial progenitor cells

    OpenAIRE

    Xiao, Xiang; Li, Lin; Xu, Shuqiang; Mao, Min; Pan, Ruiyan; Li, Yanjun; Wu, Jiayun; Huang, Li; Zheng, Xiaoyun

    2017-01-01

    Lu Rong, velvet antler (VA), is a traditional Chinese medicine, which is used as a food supplement and therapeutic drug in China, Japan, Russia, New Zealand and Southeast Asia. The regenerative characteristics of VA have resulted in great research interest, particularly regarding the fields of organ grafting and stem cell differentiation. Various VA proteomic studies verified that proteins act as the primary bioactive components of VA. The present study aimed to investigate if VA proteins (VA...

  20. Attenuated total reflectance Fourier-transform infrared spectroscopic investigation of silicon heterojunction solar cells

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; De Wolf, S.; Jiříček, Petr; Ballif, C.

    2015-01-01

    Roč. 86, č. 7 (2015), , "073108-1"-"073108-6" ISSN 0034-6748 R&D Projects: GA ČR(CZ) GA14-05053S; GA MŠk 7E12029; GA MŠk(CZ) LM2011026 EU Projects: European Commission(XE) 283501 - Fast Track Institutional support: RVO:68378271 Keywords : FTIR * ATR * solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.336, year: 2015

  1. Controlling the Solidification of Organic Photovoltaic Blends with Nucleating Agents

    KAUST Repository

    Nekuda Malik, Jennifer A.

    2014-11-20

    Blending fullerenes with a donor polymer for the fabrication of organic solar cells often leads to at least partial vitrification of one, if not both, components. For prototypical poly(3-hexylthiophene):fullerene blend, we show that the addition of a commercial nucleating agent, di(3,4-dimethyl benzylidene)sorbitol, to such binary blends accelerates the crystallization of the donor, resulting in an increase in its degree of crystallinity in as-cast structures. This allows manipulation of the extent of intermixing/ phase separation of the donor and acceptor directly from solution, offering a tool to improve device characteristics such as power conversion efficiency.

  2. Controlling the Solidification of Organic Photovoltaic Blends with Nucleating Agents

    KAUST Repository

    Nekuda Malik, Jennifer A.; Treat, Neil D.; Abdelsamie, Maged; Yu, Liyang; Li, Ruipeng; Smilgies, Detlef-M.; Amassian, Aram; Hawker, Craig J.; Chabinyc, Michael L.; Stingelin, Natalie

    2014-01-01

    Blending fullerenes with a donor polymer for the fabrication of organic solar cells often leads to at least partial vitrification of one, if not both, components. For prototypical poly(3-hexylthiophene):fullerene blend, we show that the addition of a commercial nucleating agent, di(3,4-dimethyl benzylidene)sorbitol, to such binary blends accelerates the crystallization of the donor, resulting in an increase in its degree of crystallinity in as-cast structures. This allows manipulation of the extent of intermixing/ phase separation of the donor and acceptor directly from solution, offering a tool to improve device characteristics such as power conversion efficiency.

  3. ON THE PRECISION OF THE NUCLEATOR

    Directory of Open Access Journals (Sweden)

    Javier González-Villa

    2017-06-01

    Full Text Available The nucleator is a design unbiased method of local stereology for estimating the volume of a bounded object. The only information required lies in the intersection of the object with an isotropic random ray emanating from a fixed point (called the pivotal point associated with the object. For instance, the volume of a neuron can be estimated from a random ray emanating from its nucleolus. The nucleator is extensively used in biosciences because it is efficient and easy to apply. The estimator variance can be reduced by increasing the number of rays. In an earlier paper a systematic sampling design was proposed, and theoretical variance predictors were derived, for the corresponding volume estimator. Being the only variance predictors hitherto available for the nucleator, our basic goal was to check their statistical performance by means of Monte Carlo resampling on computer reconstructions of real objects. As a plus, the empirical distribution of the volume estimator revealed statistical properties of practical relevance.

  4. Effect of Air Injection on Nucleation Rates

    DEFF Research Database (Denmark)

    Capellades Mendez, Gerard; Kiil, Søren; Dam-Johansen, Kim

    2017-01-01

    From disruption of the supersaturated solution to improved mass transfer in the crystallizing suspension, the introduction of a moving gas phase in a crystallizer could lead to improved rates of nucleation and crystal growth. In this work, saturated air has been injected to batch crystallizers...... to study the effects on formation of the first crystal and subsequent turbidity buildup. To account for the typically large sample-to-sample variation, nucleation rates were evaluated for a large number of replicates using probability distributions of induction times. The slope and the intercept...... was reduced from 69 to 13 min, and the mean induction time decreased from 128 to 36 min. The effect on aqueous solutions of l-arginine was less apparent, with a detection delay reduction from 15 to 3 min, and no significant changes on the rate of primary nucleation. These results demonstrate the potential...

  5. A variational approach to nucleation simulation.

    Science.gov (United States)

    Piaggi, Pablo M; Valsson, Omar; Parrinello, Michele

    2016-12-22

    We study by computer simulation the nucleation of a supersaturated Lennard-Jones vapor into the liquid phase. The large free energy barriers to transition make the time scale of this process impossible to study by ordinary molecular dynamics simulations. Therefore we use a recently developed enhanced sampling method [Valsson and Parrinello, Phys. Rev. Lett.113, 090601 (2014)] based on the variational determination of a bias potential. We differ from previous applications of this method in that the bias is constructed on the basis of the physical model provided by the classical theory of nucleation. We examine the technical problems associated with this approach. Our results are very satisfactory and will pave the way for calculating the nucleation rates in many systems.

  6. A parameterization of cloud droplet nucleation

    International Nuclear Information System (INIS)

    Ghan, S.J.; Chuang, C.; Penner, J.E.

    1993-01-01

    Droplet nucleation is a fundamental cloud process. The number of aerosols activated to form cloud droplets influences not only the number of aerosols scavenged by clouds but also the size of the cloud droplets. Cloud droplet size influences the cloud albedo and the conversion of cloud water to precipitation. Global aerosol models are presently being developed with the intention of coupling with global atmospheric circulation models to evaluate the influence of aerosols and aerosol-cloud interactions on climate. If these and other coupled models are to address issues of aerosol-cloud interactions, the droplet nucleation process must be adequately represented. Here we introduce a droplet nucleation parametrization that offers certain advantages over the popular Twomey (1959) parameterization

  7. Heterogeneous nucleation of ice in the atmosphere

    International Nuclear Information System (INIS)

    Nicosia, A; Piazza, M; Santachiara, G; Belosi, F

    2017-01-01

    The occurrence of ice-nucleating aerosols in the atmosphere has a profound impact on the properties of clouds, and in turn, influences our understanding on weather and climate. Research on this topic has grown constantly over the last decades, driven by advances in online and offline instruments capable of measuring the characteristics of these cloud-modifying aerosol particles. This article presents different aspects to the understanding of how aerosol particles can trigger the nucleation of ice in clouds. In addition, we present some experimental results obtained with the Dynamic Filter Processing Chamber, an off-line instrument that has been applied extensively in the last years and that circumvents some of the problems related to the measurement of Ice Nucleating Particles properties. (paper)

  8. Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count

    OpenAIRE

    Koop, G.; Dik, N.; Nielen, M.; Lipman, L.J.A.

    2010-01-01

    The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms, 3 bulk milk samples were collected at intervals of 2 wk. The samples were cultured for SPC, coliform count, and staphylococcal count and for the presence of Staphylococcus aureus. Furthermore, SCC ...

  9. Dynamics of protein aggregation and oligomer formation governed by secondary nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Michaels, Thomas C. T., E-mail: tctm3@cam.ac.uk; Lazell, Hamish W.; Arosio, Paolo; Knowles, Tuomas P. J., E-mail: tpjk2@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2015-08-07

    The formation of aggregates in many protein systems can be significantly accelerated by secondary nucleation, a process where existing assemblies catalyse the nucleation of new species. In particular, secondary nucleation has emerged as a central process controlling the proliferation of many filamentous protein structures, including molecular species related to diseases such as sickle cell anemia and a range of neurodegenerative conditions. Increasing evidence suggests that the physical size of protein filaments plays a key role in determining their potential for deleterious interactions with living cells, with smaller aggregates of misfolded proteins, oligomers, being particularly toxic. It is thus crucial to progress towards an understanding of the factors that control the sizes of protein aggregates. However, the influence of secondary nucleation on the time evolution of aggregate size distributions has been challenging to quantify. This difficulty originates in large part from the fact that secondary nucleation couples the dynamics of species distant in size space. Here, we approach this problem by presenting an analytical treatment of the master equation describing the growth kinetics of linear protein structures proliferating through secondary nucleation and provide closed-form expressions for the temporal evolution of the resulting aggregate size distribution. We show how the availability of analytical solutions for the full filament distribution allows us to identify the key physical parameters that control the sizes of growing protein filaments. Furthermore, we use these results to probe the dynamics of the populations of small oligomeric species as they are formed through secondary nucleation and discuss the implications of our work for understanding the factors that promote or curtail the production of these species with a potentially high deleterious biological activity.

  10. An experimental study of dislocation loop nucleation

    International Nuclear Information System (INIS)

    Bounaud, J.Y.; Leteurtre, J.

    1975-01-01

    The nucleation of dislocation loops is experimentally studied by observing the demixion of the Burgers vectors of dislocation loops nucleated in copper whiskers irradiated in flexion by fission fragments at room temperature. The demixion of Burgers vectors is observed by the dimensional effects of dislocation loops: after irradiation, the applied stress is removed; the whisker shows a residual strain that is due to loops because, after an annealing treatment to evaporate dislocation loops, each whisker recovers its initial straight shape. Everywhere along the whisker, the radius of curvature is measured and plotted vs the max. applied stress. Estimations of the interstitial and vacancy dislocation loop nuclei are derived [fr

  11. High performance computations using dynamical nucleation theory

    International Nuclear Information System (INIS)

    Windus, T L; Crosby, L D; Kathmann, S M

    2008-01-01

    Chemists continue to explore the use of very large computations to perform simulations that describe the molecular level physics of critical challenges in science. In this paper, we describe the Dynamical Nucleation Theory Monte Carlo (DNTMC) model - a model for determining molecular scale nucleation rate constants - and its parallel capabilities. The potential for bottlenecks and the challenges to running on future petascale or larger resources are delineated. A 'master-slave' solution is proposed to scale to the petascale and will be developed in the NWChem software. In addition, mathematical and data analysis challenges are described

  12. Crystal nucleation in simple and complex fluids.

    Science.gov (United States)

    Oxtoby, David W

    2003-03-15

    The application of density-functional methods from statistical mechanics to the nucleation of crystals from the melt is described. Simple fluids such as metals, with sizes comparable with the range of their attractive forces, are compared with complex fluids such as colloidal suspensions and proteins dissolved in solution. A different mechanism for crystal nucleation is proposed in the latter case, in which density (concentration) changes before periodic crystalline order appears. This leads to a theoretical foundation for empirical observations on the 'crystallization window' in protein crystallization. Comparisons are made with the results of computer simulation via molecular dynamics.

  13. Indirect radiative forcing by ion-mediated nucleation of aerosol

    Directory of Open Access Journals (Sweden)

    F. Yu

    2012-12-01

    Full Text Available A clear understanding of particle formation mechanisms is critical for assessing aerosol indirect radiative forcing and associated climate feedback processes. Recent studies reveal the importance of ion-mediated nucleation (IMN in generating new particles and cloud condensation nuclei (CCN in the atmosphere. Here we implement the IMN scheme into the Community Atmosphere Model version 5 (CAM5. Our simulations show that, compared to globally averaged results based on H2SO4-H2O binary homogeneous nucleation (BHN, the presence of ionization (i.e., IMN halves H2SO4 column burden, but increases the column integrated nucleation rate by around one order of magnitude, total particle number burden by a factor of ~3, CCN burden by ~10% (at 0.2% supersaturation to 65% (at 1.0% supersaturation, and cloud droplet number burden by ~18%. Compared to BHN, IMN increases cloud liquid water path by 7.5%, decreases precipitation by 1.1%, and increases total cloud cover by 1.9%. This leads to an increase of total shortwave cloud radiative forcing (SWCF by 3.67 W m−2 (more negative and longwave cloud forcing by 1.78 W m−2 (more positive, with large spatial variations. The effect of ionization on SWCF derived from this study (3.67 W m−2 is a factor of ~3 higher that of a previous study (1.15 W m−2 based on a different ion nucleation scheme and climate model. Based on the present CAM5 simulation, the 5-yr mean impacts of solar cycle induced changes in ionization rates on CCN and cloud forcing are small (~−0.02 W m−2 but have larger inter-annual (from −0.18 to 0.17 W m−2 and spatial variations.

  14. Quantitative analysis of phosphoinositide 3-kinase (PI3K) signaling using live-cell total internal reflection fluorescence (TIRF) microscopy.

    Science.gov (United States)

    Johnson, Heath E; Haugh, Jason M

    2013-12-02

    This unit focuses on the use of total internal reflection fluorescence (TIRF) microscopy and image analysis methods to study the dynamics of signal transduction mediated by class I phosphoinositide 3-kinases (PI3Ks) in mammalian cells. The first four protocols cover live-cell imaging experiments, image acquisition parameters, and basic image processing and segmentation. These methods are generally applicable to live-cell TIRF experiments. The remaining protocols outline more advanced image analysis methods, which were developed in our laboratory for the purpose of characterizing the spatiotemporal dynamics of PI3K signaling. These methods may be extended to analyze other cellular processes monitored using fluorescent biosensors. Copyright © 2013 John Wiley & Sons, Inc.

  15. Taking directions: the role of microtubule-bound nucleation in the self-organization of the plant cortical array

    International Nuclear Information System (INIS)

    Deinum, Eva E; Tindemans, Simon H; Mulder, Bela M

    2011-01-01

    The highly aligned cortical microtubule array of interphase plant cells is a key regulator of anisotropic cell expansion. Recent computational and analytical work has shown that the non-equilibrium self-organization of this structure can be understood on the basis of experimentally observed collisional interactions between dynamic microtubules attached to the plasma membrane. Most of these approaches assumed that new microtubules are homogeneously and isotropically nucleated on the cortical surface. Experimental evidence, however, shows that nucleation mostly occurs from other microtubules and under specific relative angles. Here, we investigate the impact of directed microtubule-bound nucleations on the alignment process using computer simulations. The results show that microtubule-bound nucleations can increase the degree of alignment achieved, decrease the timescale of the ordering process and widen the regime of dynamic parameters for which the system can self-organize. We establish that the major determinant of this effect is the degree of co-alignment of the nucleations with the parent microtubule. The specific role of sideways branching nucleations appears to allow stronger alignment while maintaining a measure of overall spatial homogeneity. Finally, we investigate the suggestion that observed persistent rotation of microtubule domains can be explained through a handedness bias in microtubule-bound nucleations, showing that this is possible only for an extreme bias and over a limited range of parameters

  16. Taking directions: the role of microtubule-bound nucleation in the self-organization of the plant cortical array

    Science.gov (United States)

    Deinum, Eva E.; Tindemans, Simon H.; Mulder, Bela M.

    2011-10-01

    The highly aligned cortical microtubule array of interphase plant cells is a key regulator of anisotropic cell expansion. Recent computational and analytical work has shown that the non-equilibrium self-organization of this structure can be understood on the basis of experimentally observed collisional interactions between dynamic microtubules attached to the plasma membrane. Most of these approaches assumed that new microtubules are homogeneously and isotropically nucleated on the cortical surface. Experimental evidence, however, shows that nucleation mostly occurs from other microtubules and under specific relative angles. Here, we investigate the impact of directed microtubule-bound nucleations on the alignment process using computer simulations. The results show that microtubule-bound nucleations can increase the degree of alignment achieved, decrease the timescale of the ordering process and widen the regime of dynamic parameters for which the system can self-organize. We establish that the major determinant of this effect is the degree of co-alignment of the nucleations with the parent microtubule. The specific role of sideways branching nucleations appears to allow stronger alignment while maintaining a measure of overall spatial homogeneity. Finally, we investigate the suggestion that observed persistent rotation of microtubule domains can be explained through a handedness bias in microtubule-bound nucleations, showing that this is possible only for an extreme bias and over a limited range of parameters.

  17. Evidence for mouse Th1- and Th2-like helper T cells in vivo. Selective reduction of Th1-like cells after total lymphoid irradiation

    International Nuclear Information System (INIS)

    Bass, H.; Mosmann, T.; Strober, S.

    1989-01-01

    Purified CD4+ BALB/c spleen T cells obtained 4-6 wk after total lymphoid irradiation (TLI) helped normal syngeneic B cells to produce a vigorous antibody response to TNP keyhole limpet hemocyanin in adoptive cell transfer experiments. However, the same cells failed to transfer delayed-type hypersensitivity to the adoptive hosts as measured by a foot pad swelling assay. In addition, purified CD4+ cells from TLI-treated mice were unable to induce graft vs. host disease in lethally irradiated allogeneic C57BL/Ka recipient mice. In response to mitogen stimulation, unfractionated spleen cells obtained from TLI mice secreted normal levels of IL-4 and IL-5, but markedly reduced levels of IL-2 and INF-gamma. A total of 229 CD4+ clones from spleen cells of both normal and TLI-treated mice were established, and the cytokine secretion pattern from each clone was analyzed. The results demonstrate that the ratio of Th1- and Th2-like clones in the spleens of normal BALB/c mice is 1:0.6, whereas the ratio in TLI mice is approximately 1:7. These results suggest that Th2-like cells recover rapidly (at approximately 4-6 wk) after TLI treatment and account for the early return of antibody helper activity and secretion of IL-4 and IL-5, but Th1-like cells recover more slowly (in approximately 3 mo) after irradiation, and this accounts for the deficit in cell-mediated immunity and the reduced amount of IL-2 and IFN-gamma secretion

  18. Thyroid cartilage invasion in laryngeal and hypopharyngeal squamous cell carcinoma treated with total laryngectomy.

    Science.gov (United States)

    Koopmann, Mario; Weiss, Daniel; Steiger, Matthias; Elges, Sandra; Rudack, Claudia; Stenner, Markus

    2016-11-01

    The objective of this study is to analyze the accuracy of computed tomography in detecting malignant thyroid cartilage invasion. In a retrospective chart review, 120 patients with carcinoma of the larynx and hypopharynx underwent computed tomography before total laryngectomy. These data were compared with the histological specimens. Multidetector computed tomography (MDCT) scan had a positive predictive value (PPV) of 76 % and a negative predictive value (NPV) of 69 %. The specificity of MDCT was 89 % and sensitivity was 46 %. Comparison between radiologic suspected cartilage invasion and histologic results showed a significant correlation (p < 0.02). We found no significant impact of cartilage invasion concerning survival rates (5-year overall survival p = 0.683; 5-year disease-free survival p = 0.711). Preoperative CT scan is an important instrument in detecting neoplastic cartilage invasion.

  19. Evaluation of total effort and risk of membraneless tubular fuel cell concept

    Energy Technology Data Exchange (ETDEWEB)

    Bambace, Luis Antonio Waack [Instituto Nacional de Pesquisas Espaciais - INPE, Sao Jose dos Campos, SP (Brazil)], e-mail: bambace@dem.inpe.br

    2010-07-01

    Traditionally people estimate project risks and duration by comparing predicted actions with similar ones. This methodology is rather difficult to apply in very innovative projects, as several of their Work Breakdown Structure (WBS) actions are quite new to a particular developer, even if this action is a standard procedure in another field or company. This paper proposes the use of an alternative methodology with fuel cell design example, which is inspired in Suh third axiom, Jelinsky-Moranda Model of software reliability (JMSRM). This model considers human error with JMRSR, relates the number of trials with entropy and search residual risk, feasibility with model uncertainty and acceptable and target risks, and the matching of search field and real solution field with statistical tools. (author)

  20. Nucleation of small angle boundaries

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-12-01

    Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

  1. Recovery of the Erythropoietin-Sensitive Stem-Cell Population following Total-Body X-Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Byron, J. W. [Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester (United Kingdom)

    1968-08-15

    Erythropoietin acts upon haemopoietic stem cells to initiate their differentiation into the erythroid series. This effect may be used in polycythaemic mice to estimate changes in the erythropoietin-sensitive stem-cell population following total-body irradiation (TBR). Generally, single doses of erythropoietin, less than that needed for maximum stem-cell response, are used to estimate changes in the stem-cell population. The validity of results using this test is based upon accepting several assumptions regarding erythropoietin kinetics. These are: (a) the contribution of endogenous erythropoietin is always negligible; (b) the origin of the dose-response curve to erythropoietin alters only because of changes in stem-cell numbers; (c) the proportion of stem cells responding to a given concentration of erythropoietin is independent of stem-cell numbers; (d) the slope of the dose-response curve does not alter; and (e) competition between erythropoietin and other factors for the stem cells remains unchanged. The studies to be reported indicate that some of these assumptions m a y not always be valid. Following 150 rad TBR, changes in erythropoietin dose-response curves were not always due to changes in the size of the stem-cell population, but also due to changes in erythropoietin kinetics. Changes in erythropoietin kinetics could be corrected for by using doses of erythropoietin which at any particular time after TBR gave maximum stem-cell response; through full dose-response studies, the nature of changes in erythropoietin kinetics following TBR could be established. These studies appear to explain discrepancies in results obtained in different laboratories using the erythropoietin test. The effect of 150 rad TBR on the erythropoietin-sensitive stem-cell population is an initial depression within 30 min to 20% of normal followed by a second depression (post-irradiation dip) at about 12 h. Twenty-four hours after TBR there is a recovery to the initial depression. This

  2. Effect of CaCO3(S) nucleation modes on algae removal from alkaline water.

    Science.gov (United States)

    Choi, Jin Yong; Kinney, Kerry A; Katz, Lynn E

    2016-02-29

    The role of calcite heterogeneous nucleation was studied in a particle coagulation treatment process for removing microalgae from water. Batch experiments were conducted with Scenedesmus sp. and Chlorella sp. in the presence and absence of carbonate and in the presence and absence of Mg to delineate the role of CaCO 3(S) nucleation on microalgae removal. The results indicate that effective algae coagulation (e.g., up to 81 % algae removal efficiency) can be achieved via heterogeneous nucleation with CaCO 3(S) ; however, supersaturation ratios between 120 and 200 are required to achieve at least 50% algae removal, depending on ion concentrations. Algae removal was attributed to adsorption of Ca 2+ onto the cell surface which provides nucleation sites for CaCO 3(S) precipitation. Bridging of calcite particles between the algal cells led to rapid aggregation and formation of larger flocs. However, at higher supersaturation conditions, algae removal was diminished due to the dominance of homogeneous nucleation of CaCO 3(S) . Removal of algae in the presence of Ca 2+ and Mg 2+ required higher supersaturation values; however, the shift from heteronucleation to homonucleation with increasing supersaturation was still evident. The results suggest that water chemistry, pH, ionic strength, alkalinity and Ca 2+ concentration can be optimized for algae removal via coagulation-sedimentation.

  3. Evidence for a single stem cell to reconstitute nearly one half of the total blood T cells in two A-bomb survivors

    International Nuclear Information System (INIS)

    Kodama, Y.; Nakano, M.; Itho, M.; Ohtaki, K.; Kusunoki, Y.; Nakamura, N.

    2003-01-01

    Full text: Recently, we have encountered two A-bomb survivors who had identical chromosome aberrations in their lymphocytes with very high frequencies; one survivor bore the same translocations in 40% of blood lymphocytes (case 1, estimated dose= 1.06 Sv) and the other had identical inversions and deletions in 30% of the lymphocytes (case 2, estimated dose 3.54 Sv). In case 1, the same abnormality was frequently observed in CD4 T cells, CD8 T cells, and EBV-transformed B cells as well, suggesting the origin in a bone marrow stem cell. Although it is generally thought that the clonal aberrations observed in A-bomb survivors were induced by A-bomb radiation, the results did not allow us to distinguish if the clone preexisted (i.e., as a mosaic individual) or was induced following radiation exposure. To discriminate these two possibilities, we applied 24-color FISH to detect additional non-clonal aberrations among the clonal cells. As these survivors bore various non-clonal translocations in about 30% (case 1) or 50% (case 2) of the lymphocytes that do not carry the clonal aberration, the rational is straightforward; if the clonal cells preexisted, we expected 30% or 50% of additional but non-clonal aberrations among the clonal cells. By contrast, if the clone emerged following the A-bomb radiation exposure, we expected a minimum frequency of additional aberrations among the clonal cells (i.e., close to the background aberration frequency observed in non-exposed people). The results showed that the frequency of additional translocations among the clonal cells was only 3% (3/101 cells) in case 1 and 1% (1/100) in case 2. Thus, the results clearly demonstrated that the clonal cells did not preexist and were produced as a result of extensive proliferation of a single stem cell following radiation exposure, which gave rise to comprise nearly one half of the total lymphocytes

  4. Impact of total radiotherapy dose on survival for head and neck Merkel cell carcinoma after resection.

    Science.gov (United States)

    Patel, Sagar A; Qureshi, Muhammad M; Mak, Kimberley S; Sahni, Debjani; Giacalone, Nicholas J; Ezzat, Waleed; Jalisi, Scharukh; Truong, Minh Tam

    2017-07-01

    Head and neck Merkel cell carcinoma (MCC) is commonly treated with surgery and adjuvant radiotherapy (RT) for high-risk features. The optimal radiation dose is unknown. One thousand six hundred twenty-five eligible patients with head and neck MCC were identified in the National Cancer Data Base (NCDB). Radiation dose was divided into 3 groups: 30 to 55-70 Gy. Cox regression was used to compare overall survival (OS) between groups, accounting for age, sex, stage, surgery type, margin status, comorbidities, and use of chemotherapy. With a median follow-up of 33.5 months, 3-year OS was 48.9%, 70.3%, and 58.7% for 30 to 55-70 Gy, respectively (P 55-70 Gy (adjusted HR 1.21; 95% CI 1.0-1.46; P = .06) were associated with worse survival. Adjuvant radiation doses within 50-55 Gy may be optimal for head and neck MCC. © 2017 Wiley Periodicals, Inc.

  5. NUCLEATION AND THE AUDIO-LINGUAL APPROACH.

    Science.gov (United States)

    BELASCO, SIMON

    IN THE PRE-NUCLEATION STAGE, THE STUDENT IS CONCERNED WITH STORING, OR INTERNALIZING, THREE KINDS OF LANGUAGE PATTERNS--(1) ONE REPRESENTING THE SOUND STRUCTURE, (2) ANOTHER INVOLVING A PORTION OF THE SYNTACTIC STRUCTURE, AND (3) A THIRD--CALLED SANDHI VARIATION--ARISING FROM THE ACCIDENTAL CO-OCCURRENCE OF CERTAIN SOUNDS MAKING UP THE ELEMENTS OF…

  6. Crystal nucleation kinetics in confined systems

    Czech Academy of Sciences Publication Activity Database

    Kožíšek, Zdeněk

    2013-01-01

    Roč. 15, č. 12 (2013), 2269-2274 ISSN 1466-8033 R&D Projects: GA ČR GAP108/12/0891 Institutional support: RVO:68378271 Keywords : nucleation * phase transtion Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.858, year: 2013

  7. The scales of brane nucleation processes

    International Nuclear Information System (INIS)

    Alwis, S.P. de

    2007-01-01

    The scales associated with Brown-Teitelboim-Bousso-Polchinski processes of brane nucleation, which result in changes of the flux parameters and the number of D-branes, are discussed in the context of type IIB models with all moduli stabilized. It is argued that such processes are unlikely to be described by effective field theory

  8. NUCLEATION STUDIES OF GOLD ON CARBON ELECTRODES

    Directory of Open Access Journals (Sweden)

    S. SOBRI

    2008-04-01

    Full Text Available Interest has grown in developing non-toxic electrolytes for gold electrodeposition to replace the conventional cyanide-based bath for long term sustainability of gold electroplating. A solution containing thiosulphate and sulphite has been developed specially for microelectronics applications. However, at the end of the electrodeposition process, the spent electrolyte can contain a significant amount of gold in solution. This study has been initiated to investigate the feasibility of gold recovery from a spent thiosulphate-sulphite electrolyte. We have used flat-plate glassy carbon and graphite electrodes to study the mechanism of nucleation and crystal growth of gold deposition from the spent electrolyte. It was found that at the early stages of reduction process, the deposition of gold on glassy carbon exhibits an instantaneous nucleation of non-overlapping particles. At longer times, the particles begin to overlap and the deposition follows a classic progressive nucleation phenomenon. On the other hand, deposition of gold on graphite does not follow the classical nucleation phenomena.

  9. The ice nucleation activity of extremophilic algae

    Czech Academy of Sciences Publication Activity Database

    Kvíderová, Jana; Hájek, J.; Worland, M. R.

    2013-01-01

    Roč. 34, č. 2 (2013), s. 137-148 ISSN 0143-2044 R&D Projects: GA AV ČR KJB601630808; GA AV ČR KJB600050708 Institutional support: RVO:67985939 Keywords : Ice nucleation * snow algae * lichen photobionts Subject RIV: EF - Botanics Impact factor: 0.640, year: 2013

  10. Temperature Dependence in Homogeneous and Heterogeneous Nucleation

    Energy Technology Data Exchange (ETDEWEB)

    McGraw R. L.; Winkler, P. M.; Wagner, P. E.

    2017-08-01

    Heterogeneous nucleation on stable (sub-2 nm) nuclei aids the formation of atmospheric cloud condensation nuclei (CCN) by circumventing or reducing vapor pressure barriers that would otherwise limit condensation and new particle growth. Aerosol and cloud formation depend largely on the interaction between a condensing liquid and the nucleating site. A new paper published this year reports the first direct experimental determination of contact angles as well as contact line curvature and other geometric properties of a spherical cap nucleus at nanometer scale using measurements from the Vienna Size Analyzing Nucleus Counter (SANC) (Winkler et al., 2016). For water nucleating heterogeneously on silver oxide nanoparticles we find contact angles around 15 degrees compared to around 90 degrees for the macroscopically measured equilibrium angle for water on bulk silver. The small microscopic contact angles can be attributed via the generalized Young equation to a negative line tension that becomes increasingly dominant with increasing curvature of the contact line. These results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.

  11. Nanoscale-Agglomerate-Mediated Heterogeneous Nucleation.

    Science.gov (United States)

    Cha, Hyeongyun; Wu, Alex; Kim, Moon-Kyung; Saigusa, Kosuke; Liu, Aihua; Miljkovic, Nenad

    2017-12-13

    Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH 3 SH), dimethyl disulfide (CH 3 SSCH), and dimethyl trisulfide (CH 3 SSSCH 3 ) on the liquid-vapor interface during water vapor condensation, which act as preferential sites for heterogeneous nucleation after evaporation. The insights gained from this study elucidate fundamental aspects governing the behavior of both short- and long-term heterogeneous nucleation on hydrophobic surfaces, suggest previously unexplored microfabrication and air purification techniques, and present insights into the challenges facing the development of durable dropwise condensing surfaces.

  12. Binary nucleation of water and sodium chloride

    Czech Academy of Sciences Publication Activity Database

    Němec, Tomáš; Maršík, František; Palmer, A.

    2006-01-01

    Roč. 124, č. 4 (2006), 0445091-0445096 ISSN 0021-9606 R&D Projects: GA ČR(CZ) GA101/05/2536 Institutional research plan: CEZ:AV0Z20760514 Keywords : binary nucleation * sodium chloride * water Subject RIV: BJ - Thermodynamics Impact factor: 3.166, year: 2006

  13. Cavitation nucleation in gelatin: Experiment and mechanism.

    Science.gov (United States)

    Kang, Wonmo; Adnan, Ashfaq; O'Shaughnessy, Thomas; Bagchi, Amit

    2018-02-01

    Dynamic cavitation in soft materials is becoming increasingly relevant due to emerging medical implications such as the potential of cavitation-induced brain injury or cavitation created by therapeutic medical devices. However, the current understanding of dynamic cavitation in soft materials is still very limited, mainly due to lack of robust experimental techniques. To experimentally characterize cavitation nucleation under dynamic loading, we utilize a recently developed experimental instrument, the integrated drop tower system. This technique allows quantitative measurements of the critical acceleration (a cr ) that corresponds to cavitation nucleation while concurrently visualizing time evolution of cavitation. Our experimental results reveal that a cr increases with increasing concentration of gelatin in pure water. Interestingly, we have observed the distinctive transition from a sharp increase (pure water to 1% gelatin) to a much slower rate of increase (∼10× slower) between 1% and 7.5% gelatin. Theoretical cavitation criterion predicts the general trend of increasing a cr , but fails to explain the transition rates. As a likely mechanism, we consider concentration-dependent material properties and non-spherical cavitation nucleation sites, represented by pre-existing bubbles in gels, due to possible interplay between gelatin molecules and nucleation sites. This analysis shows that cavitation nucleation is very sensitive to the initial configuration of a bubble, i.e., a non-spherical bubble can significantly increase a cr . This conclusion matches well with the experimentally observed liquid-to-gel transition in the critical acceleration for cavitation nucleation. From a medical standpoint, understanding dynamic cavitation within soft materials, i.e., tissues, is important as there are both potential injury implications (blast-induced cavitation within the brain) as well as treatments utilizing the phenomena (lithotripsy). In this regard, the main

  14. Influence of an oscillator bath on the nucleation rate

    International Nuclear Information System (INIS)

    Amritkar, R.E.

    1984-09-01

    The nucleation rate of a system in a metastable state coupled to an oscillator bath is considered. It is shown that for a weak coupling and small oscillator frequencies the nucleation rate increases. (author)

  15. Opposite effects of total lymphoid irradiation on T cell-dependent and T cell-independent antibody responses

    Energy Technology Data Exchange (ETDEWEB)

    Tanay, A.; Strober, S.

    1984-02-01

    The effect of total lymphoid irradiation (TLI) on the primary antibody response to the dinitrophenylated heterologous protein, keyhole limpet hemocyanin (DNP-KLH), in complete Freund's adjuvant (CFA), and to the trinitrophenylated polysaccharide antigen, Brucella abortus (TNP-BA), was studied in BALB/c mice. The antibody response to both antigens was diminished in comparison with nonirradiated mice when antigens were injected within 3 days after TLI. When the mice were immunized 30 days after completion of TLI the antibody response to DNP-KLH in CFA was still diminished, but the antibody response to TNP-BA was enhanced 5- to 10-fold as compared with that of control animals. The opposite effect of TLI on the two antibody responses was also observed in a syngeneic primary adoptive transfer system.

  16. Fibrin sealants or cell saver eliminate the need for autologous blood donation in anemic patients undergoing primary total knee arthroplasty.

    Science.gov (United States)

    Bou Monsef, Jad; Buckup, Johannes; Waldstein, Wenzel; Cornell, Charles; Boettner, Friedrich

    2014-01-01

    Reducing allogeneic blood transfusions remains a challenge in total knee arthroplasty. Patients with preoperative anemia have a particularly high risk for perioperative blood transfusions. 176 anemic patients (Hb < 13.5 g/dl) undergoing total knee replacement were prospectively evaluated to compare the effect of a perioperative cell saver (26 patients), intraoperative fibrin sealants (5 ml Evicel, Johnson & Johnson Wound Management, Ethicon, Somerville, NJ) (45 patients), preoperative autologous blood donation (PABD) (21 patients), the combination of fibrin sealants and preoperative autologous blood donation (44) and no intervention (40 patients) on perioperative blood loss and transfusion requirements. All protocols resulted in significant reduction of allogeneic blood transfusions. Transfusion rates were similar with the use of PABD (19%), Evicel (18%), and cell saver (19%), all significantly lower than the control group (38 %, p < 0.05). Combining Evicel with PABD resulted in significantly higher wastage of autologous units (p < 0.05) with no significant reduction in allogeneic transfusion rate (14%). The use of fibrin sealant resulted in a significant reduction of blood loss compared to the PABD group (603 vs. 810 ml, p < 0.005) as well as the control group (603 vs. 822 ml, p < 0.005). While PABD proved to be the most cost-effective treatment option in anemic patients, fibrin sealants and cell saver show similar reduction in allogeneic transfusion rates compared to controls. The combination of fibrin sealants and PABD is not cost-effective and increases the number of wasted units.

  17. Perioperative Allogeneic Red Blood-Cell Transfusion Associated with Surgical Site Infection After Total Hip and Knee Arthroplasty.

    Science.gov (United States)

    Everhart, Joshua S; Sojka, John H; Mayerson, Joel L; Glassman, Andrew H; Scharschmidt, Thomas J

    2018-02-21

    Perioperative allogeneic red blood-cell transfusion is a suspected risk factor for surgical site infection (SSI) after total joint arthroplasty (TJA), but the interrelationships among SSI risk, transfusion dose, preoperative anemia, and the presence of coagulopathies have not been well described. Data on SSI within 1 year after surgery as well as on transfusion with blood products within 30 days after surgery were obtained for 6,788 patients who had undergone primary or revision total hip or knee arthroplasty from 2000 to 2011 in a single hospital system. Multivariate logistic regression modeling was used to determine the independent association between allogeneic red blood-cell transfusion and SSI. There was a dose-dependent association between allogeneic red blood-cell transfusion and SSI, with the infection rate increasing as the transfusion dose increased from 1 unit (odds ratio [OR] = 1.97; 95% confidence interval [CI] = 1.38, 2.79; p 3 units (OR = 7.40; CI = 4.91, 11.03; p conservation strategies. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

  18. Pretreatment red blood cell total folate is associated with response to pemetrexed in stage IV non-squamous non-small-cell lung cancer

    Science.gov (United States)

    Bagley, Stephen J.; Vitale, Steven; Zhang, Suhong; Aggarwal, Charu; Evans, Tracey L.; Alley, Evan W.; Cohen, Roger B.; Langer, Corey J.; Blair, Ian A.; Vachani, Anil; Whitehead, Alexander S.

    2016-01-01

    Objectives Pemetrexed inhibits folate-dependent enzymes involved in pyrimidine and purine synthesis. Prior studies of genetic variation in these enzymes as predictors of pemetrexed efficacy have yielded inconsistent results. We investigated whether red blood cell (RBC) total folate, a phenotypic rather than genotypic marker of cellular folate status, was associated with response to pemetrexed-based chemotherapy in advanced non-squamous non-small-cell lung cancer (NSCLC). Materials and methods We conducted a prospective cohort study of patients with stage IV non-squamous NSCLC receiving first-line chemotherapy containing pemetrexed. Pretreatment RBC total folate was quantified using liquid chromatography/mass spectrometry. We then compared objective response rate (ORR) between patients with RBC total folate concentrations above and below an optimal cut-off value determined from the receiver operating characteristic (ROC) curve. A logistic regression model was used to adjust for age, sex, and use of bevacizumab. Results The ORR was 62% (32 of 52 patients). ROC analysis was used to establish that a RBC total folate cutoff value of 364.6 nM optimally discriminated between pemetrexed responders and non-responders. Patients with RBC total folate below 364.5 nM had an ORR of 27%, compared to 71% in patients with RBC total folate above this value (p=0.01). This difference persisted after adjusting for age, sex, and use of bevacizumab (OR 0.07, 95% CI 0.01 - 0.57, p=0.01). Conclusions Low pretreatment RBC total folate is associated with inferior response to pemetrexed-based chemotherapy in stage IV non-squamous NSCLC. Larger, multicenter studies are needed to validate RBC total folate as a predictive marker of pemetrexed response. PMID:27863923

  19. Anatomic Mesenchymal Stem Cell-Based Engineered Cartilage Constructs for Biologic Total Joint Replacement

    Science.gov (United States)

    Saxena, Vishal; Kim, Minwook; Keah, Niobra M.; Neuwirth, Alexander L.; Stoeckl, Brendan D.; Bickard, Kevin; Restle, David J.; Salowe, Rebecca; Wang, Margaret Ye; Steinberg, David R.

    2016-01-01

    Cartilage has a poor healing response, and few viable options exist for repair of extensive damage. Hyaluronic acid (HA) hydrogels seeded with mesenchymal stem cells (MSCs) polymerized through UV crosslinking can generate functional tissue, but this crosslinking is not compatible with indirect rapid prototyping utilizing opaque anatomic molds. Methacrylate-modified polymers can also be chemically crosslinked in a cytocompatible manner using ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED). The objectives of this study were to (1) compare APS/TEMED crosslinking with UV crosslinking in terms of functional maturation of MSC-seeded HA hydrogels; (2) generate an anatomic mold of a complex joint surface through rapid prototyping; and (3) grow anatomic MSC-seeded HA hydrogel constructs using this alternative crosslinking method. Juvenile bovine MSCs were suspended in methacrylated HA (MeHA) and crosslinked either through UV polymerization or chemically with APS/TEMED to generate cylindrical constructs. Minipig porcine femoral heads were imaged using microCT, and anatomic negative molds were generated by three-dimensional printing using fused deposition modeling. Molded HA constructs were produced using the APS/TEMED method. All constructs were cultured for up to 12 weeks in a chemically defined medium supplemented with TGF-β3 and characterized by mechanical testing, biochemical assays, and histologic analysis. Both UV- and APS/TEMED-polymerized constructs showed increasing mechanical properties and robust proteoglycan and collagen deposition over time. At 12 weeks, APS/TEMED-polymerized constructs had higher equilibrium and dynamic moduli than UV-polymerized constructs, with no differences in proteoglycan or collagen content. Molded HA constructs retained their hemispherical shape in culture and demonstrated increasing mechanical properties and proteoglycan and collagen deposition, especially at the edges compared to the center of these

  20. Clonorchis sinensis-derived total protein attenuates airway inflammation in murine asthma model by inducing regulatory T cells and modulating dendritic cell functions

    International Nuclear Information System (INIS)

    Jeong, Young-Il; Kim, Seung Hyun; Ju, Jung Won; Cho, Shin Hyeong; Lee, Won Ja; Park, Jin Wook; Park, Yeong-Min; Lee, Sang Eun

    2011-01-01

    Highlights: → Treatment with Clonorchis sinensis-derived total protein attenuates OVA-induced airway inflammation and AHR to methacholine. → Induction of CD4 + CD25 + Foxp3 + T cells and IL-10 along with suppression of splenocyte proliferation by C. sinensis-derived total protein. → C. sinensis-derived total protein interferes with the expression of co-stimulatory molecules in DCs. -- Abstract: Asthma is characterized by Th2-mediated inflammation, resulting in airway hyperresponsiveness (AHR) through airway remodeling. Recent epidemiological and experimental reports have suggested an inverse relationship between the development of allergy and helminth infections. Infection by Clonorchis sinensis, a liver fluke that resides in the bile duct of humans, is endemic predominantly in Asia including Korea and China. Using a murine model for asthma, we investigated the effects of C. sinensis-derived total protein (Cs-TP) on allergen-induced airway inflammation and the mechanism underlying the protective effects of Cs-TP administration on asthma. Treatment with Cs-TP attenuated OVA-induced airway inflammation and methacholine-induced AHR, as well as eosinophilia development, lymphocyte infiltration into the lung, and goblet cell metaplasia. This protective effect of Cs-TP is associated with markedly reduced OVA-specific IgE and Th1/Th2 cytokine production. Moreover, Cs-TP increased the number of CD4 + CD25 + Foxp3 + regulatory T (Treg) cells as well as their suppressive activity. In fact, proliferation of OVA-restimulated splenocytes was suppressed significantly. Cs-TP also inhibited the expression of such co-stimulatory molecules as CD80, CD86, and CD40 in LPS- or OVA-stimulated dendritic cells (DCs), suggesting that Cs-TP could interfere with the capacity of airway DCs to prime naive T cells. These data demonstrate the capacity of C. sinensis to ameliorate allergic asthma and broaden our understanding of the paradoxical relationship between the allergic immune

  1. Heterogeneous ice nucleation in aqueous solutions: the role of water activity.

    Science.gov (United States)

    Zobrist, B; Marcolli, C; Peter, T; Koop, T

    2008-05-01

    Heterogeneous ice nucleation experiments have been performed with four different ice nuclei (IN), namely nonadecanol, silica, silver iodide and Arizona test dust. All IN are either immersed in the droplets or located at the droplets surface. The IN were exposed to various aqueous solutions, which consist of (NH4)2SO4, H2SO4, MgCl2, NaCl, LiCl, Ca(NO3)2, K2CO3, CH3COONa, ethylene glycol, glycerol, malonic acid, PEG300 or a NaCl/malonic acid mixture. Freezing was studied using a differential scanning calorimeter and a cold finger cell. The results show that the heterogeneous ice freezing temperatures decrease with increasing solute concentration; however, the magnitude of this effect is solute dependent. In contrast, when the results are analyzed in terms of the solution water activity a very consistent behavior emerges: heterogeneous ice nucleation temperatures for all four IN converge each onto a single line, irrespective of the nature of the solute. We find that a constant offset with respect to the ice melting point curve, Deltaaw,het, can describe the observed freezing temperatures for each IN. Such a behavior is well-known for homogeneous ice nucleation from supercooled liquid droplets and has led to the development of water-activity-based ice nucleation theory. The large variety of investigated solutes together with different general types of ice nuclei studied (monolayers, ionic crystals, covalently bound network-forming compounds, and a mixture of chemically different crystallites) underlines the general applicability of water-activity-based ice nucleation theory also for heterogeneous ice nucleation in the immersion mode. Finally, the ice nucleation efficiencies of the various IN, as well as the atmospheric implication of the developed parametrization are discussed.

  2. Molecular dynamics simulations of bubble nucleation in dark matter detectors.

    Science.gov (United States)

    Denzel, Philipp; Diemand, Jürg; Angélil, Raymond

    2016-01-01

    Bubble chambers and droplet detectors used in dosimetry and dark matter particle search experiments use a superheated metastable liquid in which nuclear recoils trigger bubble nucleation. This process is described by the classical heat spike model of F. Seitz [Phys. Fluids (1958-1988) 1, 2 (1958)PFLDAS0031-917110.1063/1.1724333], which uses classical nucleation theory to estimate the amount and the localization of the deposited energy required for bubble formation. Here we report on direct molecular dynamics simulations of heat-spike-induced bubble formation. They allow us to test the nanoscale process described in the classical heat spike model. 40 simulations were performed, each containing about 20 million atoms, which interact by a truncated force-shifted Lennard-Jones potential. We find that the energy per length unit needed for bubble nucleation agrees quite well with theoretical predictions, but the allowed spike length and the required total energy are about twice as large as predicted. This could be explained by the rapid energy diffusion measured in the simulation: contrary to the assumption in the classical model, we observe significantly faster heat diffusion than the bubble formation time scale. Finally we examine α-particle tracks, which are much longer than those of neutrons and potential dark matter particles. Empirically, α events were recently found to result in louder acoustic signals than neutron events. This distinction is crucial for the background rejection in dark matter searches. We show that a large number of individual bubbles can form along an α track, which explains the observed larger acoustic amplitudes.

  3. Nucleation barrier reconstruction via the seeding method in a lattice model with competing nucleation pathways.

    Science.gov (United States)

    Lifanov, Yuri; Vorselaars, Bart; Quigley, David

    2016-12-07

    We study a three-species analogue of the Potts lattice gas model of nucleation from solution in a regime where partially disordered solute is a viable thermodynamic phase. Using a multicanonical sampling protocol, we compute phase diagrams for the system, from which we determine a parameter regime where the partially disordered phase is metastable almost everywhere in the temperature-fugacity plane. The resulting model shows non-trivial nucleation and growth behaviour, which we examine via multidimensional free energy calculations. We consider the applicability of the model in capturing the multi-stage nucleation mechanisms of polymorphic biominerals (e.g., CaCO 3 ). We then quantitatively explore the kinetics of nucleation in our model using the increasingly popular "seeding" method. We compare the resulting free energy barrier heights to those obtained via explicit free energy calculations over a wide range of temperatures and fugacities, carefully considering the propagation of statistical error. We find that the ability of the "seeding" method to reproduce accurate free energy barriers is dependent on the degree of supersaturation, and severely limited by the use of a nucleation driving force Δμ computed for bulk phases. We discuss possible reasons for this in terms of underlying kinetic assumptions, and those of classical nucleation theory.

  4. Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation

    Science.gov (United States)

    Stopelli, E.; Conen, F.; Zimmermann, L.; Alewell, C.; Morris, C. E.

    2014-01-01

    For decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications for cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 °C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around -4 °C. In the second assay, we indicate the possibility of increasingly isolating a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus for providing new points of view in biological ice nucleation research.

  5. Non stationary nucleation: the model with minimal environment

    OpenAIRE

    Kurasov, Victor

    2013-01-01

    A new model to calculate the rate of nucleation is formulated. This model is based on the classical nucleation theory but considers also vapor depletion around the formed embryo. As the result the free energy has to be recalculated which brings a new expression for the nucleation rate.

  6. Delays due to gas diffusion in flash boiling nucleation

    International Nuclear Information System (INIS)

    Hanbury, W.T.; McCartney, W.S.

    1976-01-01

    A theoretical model to account for the time delay between decompression and nucleation in flash boiling is presented and analyzed. It shows that gas diffusion can be responsible for delayed nucleation when the critical radius for nucleation and the suspended particle size are of the same order of magnitude

  7. Nucleation, Melting Behaviour and Mechanical Properties of Poly(L ...

    African Journals Online (AJOL)

    Anew category of nucleating agent for poly(L-lactic acid) (PLLA) was developed. An organic nucleating agent; N,N'-bis(benzoyl) suberic acid dihydrazide (NA) was synthesized from benzoyl hydrazine and suberoyl chloride which was deprived from suberic acid via acylation. The nucleation, melting behaviour and ...

  8. Simulations of a non-Markovian description of nucleation

    NARCIS (Netherlands)

    Kuipers, J.; Barkema, G.T.

    2010-01-01

    In most nucleation theories, the state of a nucleating system is described by a distribution of droplet masses and this distribution evolves as a memoryless stochastic process. This is incorrect for a large class of nucleating systems. In a recent paper [ J. Kuipers and G. T. Barkema, Phys. Rev. E

  9. Nucleation of colloidal crystals on configurable seed structures

    NARCIS (Netherlands)

    Hermes, M; Vermolen, E.C.M.; Leunissen, M.E.; Vossen, D.L.J.; van Oostrum, P.D.J.; Dijkstra, M.; van Blaaderen, A.

    2011-01-01

    Nucleation is an important stage in the growth of crystals. During this stage, the structure and orientation of a crystal are determined. However, short time- and length-scales make nucleation poorly understood. Micrometer-sized colloidal particles form an ideal model system to study nucleation due

  10. Spreading Sequence Design for Multiple Cell Synchronous DS-CDMA Systems under Total Weighted Squared Correlation Criterion

    Directory of Open Access Journals (Sweden)

    Cotae Paul

    2004-01-01

    Full Text Available An algorithm for designing spreading sequences for an overloaded multicellular synchronous DS-CDMA system on uplink is introduced. The criterion used to measure the optimality of the design is the total weighted square correlation (TWSC assuming the channel state information known perfectly at both transmitter and receiver. By using this algorithm it is possible to obtain orthogonal generalized WBE sequences sets for any processing gain. The bandwidth of initial generalized WBE signals of each cell is preserved in the extended signal space associated to multicellular system. Mathematical formalism is illustrated by selected numerical examples.

  11. Total skin electron beam therapy for cutaneous T-cell lymphoma: a nationwide cohort study from Denmark

    DEFF Research Database (Denmark)

    Lindahl, Lise M; Kamstrup, Maria Rørbæk; Petersen, Peter M

    2011-01-01

    Background. Total skin electron beam therapy (TSEBT) is an effective palliative treatment for cutaneous T-cell lymphoma (CTCL). In the present study we reviewed the clinical response to TSEBT in Danish patients with CTCL. Material and methods. This retrospective study included 35 patients with CTCL...... to treatment compared to patients treated with high-dose. Consequently the study with low-dose was discontinued and published. In patients treated with high-dose the overall response rate was 100%. Complete response (CR) rate was 68% and CR occurred after a median time of 2.1 months (range 1.8 months-2.0 years...

  12. Incidence of interstitial pneumonia after hyperfractionated total body irradiation before autologous bone marrow/stem cell transplantation

    International Nuclear Information System (INIS)

    Lohr, F.; Schraube, P.; Wenz, F.; Flentje, M.; Kalle, K. von; Haas, R.; Hunstein, W.; Wannenmacher, M.

    1995-01-01

    Purpose/Objectives Interstitial pneumonia (IP) is a severe complication after allogenic bone marrow transplantation (BMT) with incidence rates between 10 % and 40 % in different series. It is a polyetiologic disease that occurs depending on age, graft vs. host disease (GvHD), CMV-status, total body irradiation (TBI) and immunosuppressive therapy after BMT. The effects of fractionation and dose rate are not entirely clear. This study evaluates the incidence of lethal IP after hyperfractionated TBI for autologous BMT or stem cell transplantation. Materials and Methods Between 1982 and 1992, 182 patients (60 % male, 40 % female) were treated with hyperfractionated total body irradiation (TBI) before autologous bone marrow transplantation. Main indications were leukemias and lymphomas (53 % AML, 21 % ALL, 22 % NHL, 4 % others) Median age was 30 ys (15 - 55 ys). A total dose of 14.4 Gy was applied using lung blocks (12 fractions of 1.2 Gy in 4 days, dose rate 7-18 cGy/min, lung dose 9 - 9.5 Gy). TBI was followed by cyclophosphamide (200 mg/kg). 72 % were treated with bone marrow transplantation, 28 % were treated with stem cell transplantation. Interstitial pneumonia was diagnosed clinically, radiologically and by autopsy. Results 4 patients died most likely of interstitial pneumonia. For another 12 patients interstitial pneumonia was not the most likely cause of death but could not be excluded. Thus, the incidence of lethal IP was at least 2.2 % but certainly below 8.8 %. Conclusion Lethal interstitial pneumonia is a rare complication after total body irradiation before autologous bone marrow transplantation in this large, homogeously treated series. In the autologous setting, total doses of 14.4 Gy can be applied with a low risk for developing interstitial pneumonia if hyperfractionation and lung blocks are used. This falls in line with data from series with identical twins or t-cell depleted marrow and smaller, less homogeneous autologous transplant studies. Thus

  13. Pretreatment Red Blood Cell Total Folate Concentration Is Associated With Response to Pemetrexed in Stage IV Nonsquamous Non-Small-cell Lung Cancer.

    Science.gov (United States)

    Bagley, Stephen J; Vitale, Steven; Zhang, Suhong; Aggarwal, Charu; Evans, Tracey L; Alley, Evan W; Cohen, Roger B; Langer, Corey J; Blair, Ian A; Vachani, Anil; Whitehead, Alexander S

    2017-03-01

    Pemetrexed inhibits folate-dependent enzymes involved in pyrimidine and purine synthesis. Previous studies of genetic variation in these enzymes as predictors of pemetrexed efficacy have yielded inconsistent results. We investigated whether red blood cell (RBC) total folate, a phenotypic rather than genotypic, marker of cellular folate status was associated with the response to pemetrexed-based chemotherapy in advanced nonsquamous non-small-cell lung cancer (NSCLC). We conducted a prospective cohort study of patients with stage IV nonsquamous NSCLC receiving first-line chemotherapy containing pemetrexed. The pretreatment RBC total folate level was quantified using liquid chromatography mass spectrometry. We then compared the objective response rate (ORR) between patients with RBC total folate concentrations greater than and less than an optimal cutoff value determined from the receiver operating characteristic curve. A logistic regression model was used to adjust for age, sex, and the use of bevacizumab. The ORR was 62% (32 of 52 patients). Receiver operating characteristic analysis was used to establish that a RBC total folate cutoff value of 364.6 nM optimally discriminated between pemetrexed responders and nonresponders. Patients with RBC total folate  364.5 nM (P = .01). This difference persisted after adjusting for age, sex, and the use of bevacizumab (odds ratio, 0.07; 95% confidence interval, 0.01-0.57; P = .01). A low pretreatment RBC total folate was associated with an inferior response to pemetrexed-based chemotherapy in stage IV nonsquamous NSCLC. Larger, multicenter studies are needed to validate RBC total folate as a predictive marker of pemetrexed response. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Nucleation Characteristics in Physical Experiments/explosions

    International Nuclear Information System (INIS)

    Henry, R.E.; Fauske, Hans K.

    1976-01-01

    Large-scale vapor explosion experiments have shown that intimate contact between hot and cold liquids, and a temperature upon contact that is greater than the spontaneous nucleation temperature of the system, are two necessary conditions for the onset of large scale vapor explosions. A model, based on spontaneous nucleation of the homogeneous type, has been proposed to describe the relevant processes and the resulting energetics for explosive boiling systems. The model considers that spontaneous nucleation cannot occur either during the relief time for constant volume heating or until the thermal boundary layer is sufficiently thick to support a vapor cavity of the critical size. After nucleation, bubble growth does not occur until an acoustic wave establishes a pressure gradient in the cold liquid. These considerations lead to the prediction that, for a given temperature, drops greater than a critical size will remain in film boiling due to coalescence of vapor nuclei and drops smaller than this value will wet and be captured by the hot liquid surface. These results are compared to small drop data for well-wetted systems and excellent agreement is obtained between the observed behavior and the model predictions. In conclusion: A model, based on spontaneous nucleation, has been proposed to describe vaporization potential and behavior upon contact in a liquid/liquid system. This behavior is determined by the size of the liquid mass, single-phase pressurization and acoustic relief, nucleation frequency due to random density fluctuations, the initiation of unstable growth and acoustic relief, and the development of the thermal boundary layer in the cold liquid. The proposed model predicts that the stability of a given size drop upon intimate contact with another liquid is extremely dependent upon the interface temperature. For low interface temperatures, large masses will be captured by the hot liquid and the resulting vaporization rates will be extremely low because

  15. Nucleation control and inhibition of BaTiO3 films using hydrothermal-electrochemical method

    International Nuclear Information System (INIS)

    Escobar, Ivan; Silva, Carmen; Silva, Eric; Vargas, Tomas; Fuenzalida, Victor

    1999-01-01

    The microstructure of BaTiO 3 films on titanium by the hydrothermal-electrochemical method was investigated using a three electrode high pressure electrochemical cell in a 0.2 M Ba(OH) 2 electrolyte at 150 0 C. The spontaneous initial linked to pure hydrothermal BaTiO 3 formation can be inhibited by cathodically protecting titanium electrode since its immersion in the electrolyte. The application of initial nucleation pulses of varying the cathodic potentials affected the grain size of the deposit. It is suggested that the formation of a titanium oxide layers is a necessary step previous to the nucleation of BaTiO 3

  16. Conjugate heat transfer effects on wall bubble nucleation in subcooled flashing flows

    International Nuclear Information System (INIS)

    Peterson, P.F.; Hijikata, K.

    1990-01-01

    A variety of models have been proposed to explain observations that large liquid superheat is required to initiate nucleation in flashing flows of subcooled liquids in nozzles, cracks and pipes. In such flows an abrupt change in the fluid temperature occurs downstream of the nucleating cavities. This paper examines the subcooling of the nucleating cavities due to conjugate heat transfer to the cold downstream fluid. This examination suggests a mechanism limiting the maximum active cavity size. Simple analysis shows that, of the total superheat required to initiate flashing, a substantial portion results from conjugate wall subcooling, which decreases the cavity vapor pressure. The specific case of flashing critical nozzle flow is examined in detail. Here boundary-layer laminarization due to the strong favorable pressure gradient aids the analysis of conjugate heat transfer

  17. Lamellipodia nucleation by filopodia depends on integrin occupancy and downstream Rac1 signaling

    International Nuclear Information System (INIS)

    Guillou, Herve; Depraz-Depland, Adeline; Planus, Emmanuelle; Vianay, Benoit; Chaussy, Jacques; Grichine, Alexei; Albiges-Rizo, Corinne; Block, Marc R.

    2008-01-01

    Time-lapse video-microscopy unambiguously shows that fibroblast filopodia are the scaffold of lamellipodia nucleation that allows anisotropic cell spreading. This process was dissected into elementary stages by monitoring cell adhesion on micropatterned extracellular matrix arrays of various pitches. Adhesion structures are stabilized by contact with the adhesive plots and subsequently converted into lamellipodia-like extensions starting at the filopodia tips. This mechanism progressively leads to full cell spreading. Stable expression of the dominant-negative Rac1 N17 impairs this change in membrane extension mode and stops cell spreading on matrix arrays. Similar expression of the dominant-negative Cdc42 N17 impairs cell spreading on homogenous and structured substrate, suggesting that filopodia extension is a prerequisite for cell spreading in this model. The differential polarity of the nucleation of lamellipodial structures by filopodia on homogenous and structured surfaces starting from the cell body and of filopodia tip, respectively, suggested that this process is triggered by areas that are in contact with extracellular matrix proteins for longer times. Consistent with this view, wild-type cells cannot spread on microarrays made of function blocking or neutral anti-β 1 integrin antibodies. However, stable expression of a constitutively active Rac1 mutant rescues the cell ability to spread on these integrin microarrays. Thereby, lamellipodia nucleation by filopodia requires integrin occupancy by matrix substrate and downstream Rac1 signaling

  18. Vapor nucleation paths in lyophobic nanopores.

    Science.gov (United States)

    Tinti, Antonio; Giacomello, Alberto; Casciola, Carlo Massimo

    2018-04-19

    In recent years, technologies revolving around the use of lyophobic nanopores gained considerable attention in both fundamental and applied research. Owing to the enormous internal surface area, heterogeneous lyophobic systems (HLS), constituted by a nanoporous lyophobic material and a non-wetting liquid, are promising candidates for the efficient storage or dissipation of mechanical energy. These diverse applications both rely on the forced intrusion and extrusion of the non-wetting liquid inside the pores; the behavior of HLS for storage or dissipation depends on the hysteresis between these two processes, which, in turn, are determined by the microscopic details of the system. It is easy to understand that molecular simulations provide an unmatched tool for understanding phenomena at these scales. In this contribution we use advanced atomistic simulation techniques in order to study the nucleation of vapor bubbles inside lyophobic mesopores. The use of the string method in collective variables allows us to overcome the computational challenges associated with the activated nature of the phenomenon, rendering a detailed picture of nucleation in confinement. In particular, this rare event method efficiently searches for the most probable nucleation path(s) in otherwise intractable, high-dimensional free-energy landscapes. Results reveal the existence of several independent nucleation paths associated with different free-energy barriers. In particular, there is a family of asymmetric transition paths, in which a bubble forms at one of the walls; the other family involves the formation of axisymmetric bubbles with an annulus shape. The computed free-energy profiles reveal that the asymmetric path is significantly more probable than the symmetric one, while the exact position where the asymmetric bubble forms is less relevant for the free energetics of the process. A comparison of the atomistic results with continuum models is also presented, showing how, for simple

  19. Total glucosides of paeony induces regulatory CD4(+)CD25(+) T cells by increasing Foxp3 demethylation in lupus CD4(+) T cells.

    Science.gov (United States)

    Zhao, Ming; Liang, Gong-ping; Tang, Mei-ni; Luo, Shuang-yan; Zhang, Jing; Cheng, Wen-jing; Chan, Tak-mao; Lu, Qian-jin

    2012-05-01

    Total glucosides of paeony (TGP), an active compound extracted from Paeony root, has been used in therapy for autoimmune diseases. However the molecular mechanism of TGP in the prevention of autoimmune response remains unclear. In this study, we found that TGP treatment significantly increased the percentage and number of Treg cells in lupus CD4(+) T cells. Further investigation revealed that treatment with TGP increased the expression of Foxp3 in lupus CD4(+) T cells by down-regulating Foxp3 promoter methylation levels. However, we couldn't observe similar results in healthy control CD4(+) T cells treated by TGP. Moreover, our results also showed that IFN-γ and IL-2 expression was enhanced in TGP-treated lupus CD4(+) T cells. These findings indicate that TGP inhibits autoimmunity in SLE patients possibly by inducing Treg cell differentiation, which may in turn be due to its ability to regulate the methylation status of the Foxp3 promoter and activate IFN-γ and IL-2 signaling. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Serum Total Tryptase Level Confirms Itself as a More Reliable Marker of Mast Cells Burden in Mast Cell Leukaemia (Aleukaemic Variant

    Directory of Open Access Journals (Sweden)

    P. Savini

    2015-01-01

    Full Text Available Mast cell leukemia (MCL is a very rare form of systemic mastocytosis (SM with a short median survival of 6 months. We describe a case of a 65-year-old woman with aleukaemic variant of MCL with a very high serum total tryptase level of 2255 μg/L at diagnosis, which occurred following an episode of hypotensive shock. She fulfilled the diagnostic criteria of SM, with a bone marrow smear infiltration of 50–60% of atypical mast cells (MCs. She tested negative for the KIT D816V mutation, without any sign of organ damage (no B- or C-findings and only few mediator-related symptoms. She was treated with antihistamine alone and then with imatinib for the appearance of anemia. She maintained stable tryptase level and a very indolent clinical course for twenty-two months; then, she suddenly progressed to acute MCL with a serum tryptase level up to 12960 μg/L. The patient died due to haemorrhagic diathesis twenty-four months after diagnosis. This clinical case maybe represents an example of the chronic form of mast cell leukemia, described as unpredictable disease, in which the serum total tryptase level has confirmed itself as a reliable marker of mast cells burden regardless of the presence of other signs or symptoms.

  1. Ion irradiation enhanced crystal nucleation in amorphous Si thin films

    International Nuclear Information System (INIS)

    Im, J.S.; Atwater, H.A.

    1990-01-01

    The nucleation kinetics of the amorphous-to-crystal transition of Si films under 1.5 MeV Xe + irradiation have been investigated by means of in situ transmission electron microscopy in the temperature range T=500--580 degree C. After an incubation period during which negligible nucleation occurs, a constant nucleation rate was observed in steady state, suggesting that homogeneous nucleation occurred. Compared to thermal crystallization, a significant enhancement in the nucleation rate during high-energy ion irradiation (five to seven orders of magnitude) was observed with an apparent activation energy of 3.9±0.75 eV

  2. Aerosol nucleation and growth and their coupling to thermal hydraulics

    International Nuclear Information System (INIS)

    Clement, C.F.

    1985-01-01

    We examine the physical processes leading to vapour condensation as an aerosol in the formation and cooling of vapour-gas mixtures. Requirements for mathematical, computer and experimental modelling are discussed in relation to nuclear aerosols. In the absence of sudden pressure drops we give a complete schematic set of equations which govern the motion of aerosol, vapour, gas and heat including radiation. The coupling to the aerosol equation is mainly through the droplet growth rate, R, and a nucleation term whose possible forms are described. Rapid equilibration between vapour and aerosol means that the likely heterogeneous nucleation term must be treated separately. General forms are given for the coupling terms in the equations for vapour concentration and temperature in terms of the local mass transfer rate to the aerosol. The properties of this quantity are shown clearly by an expression for it obtained in terms of Lewis and condensation numbers and the quantify, zeta, whose derivative gives the local total heat transfer rate. Sizes of these numbers are given for some relevant vapour-gas mixtures. Throughout the paper we give the physical requirements necessary to make the transitions to the more calculable cases of uniform or well-mixed aerosols, and finally we discuss the case of initially unsaturated vapour-gas mixtures. (orig.)

  3. Buckyball Nucleation of HiPco Tubes

    Science.gov (United States)

    Smalley, Richard E.

    2012-01-01

    The purpose of this innovation is to enhance nucleation of single-wall nanotubes (SWNTs) in the HiPco process, selectively producing 10,10 tubes, something which until now has not been thought possible. This is accomplished by injecting C60, or a derivative of C60, solubilized in supercritical CO2 together with a transition metal carboneal cocatalyst into the HiPco reactor. This is a variant on the supercritical disclosure. C60 has never been used to nucleate carbon nanotubes in the gas phase. C60 itself may not have adequate solubility in supercritical CO2. However, fluorinated C60, e.g., C60F36, is easy to make cheaply and should have much enhanced solubility.

  4. Bulk liquid undercooling and nucleation in nickel

    Energy Technology Data Exchange (ETDEWEB)

    Bokeloh, Joachim; Moros, Anna; Wilde, Gerhard [Institut fuer Materialphysik, Westfaelische Wilhelms-Universitaet Muenster (Germany)

    2010-07-01

    While classical nucleation theory is widely accepted textbook knowledge, it is somewhat lacking with regard to the atomistic details of the nucleation and growth mechanisms. Right now, there are many efforts in exploring these details with computational methods. However, only few experimental methods that can corroborate these results are available. The best known of these experimental methods are containerless processing in levitation melting and the investigation of fine droplet dispersions. We present here data on the liquid undercooling behaviour of Ni obtained by repeated melting and crystallization in a DTA. This method allows to acquire a statistically meaningful data set under clean and reproducible conditions, while still allowing reasonable sample sizes, thus combining several advantages of the two methods mentioned above. Ni was chosen as a model system because it shows good levels of undercooling and because it is well suited for computer simulations due to its relatively low number of electrons.

  5. Onset of runaway nucleation in aerosol reactors

    Science.gov (United States)

    Wu, Jin Jwang; Flagan, Richard C.

    1987-01-01

    The onset of homogeneous nucleation of new particles from the products of gas phase chemical reactions was explored using an aerosol reactor in which seed particles of silicon were grown by silane pyrolysis. The transition from seed growth by cluster deposition to catastrophic nucleation was extremely abrupt, with as little as a 17 percent change in the reactant concentration leading to an increase in the concentration of measurable particles of four orders of magnitude. From the structure of the particles grown near this transition, it is apparent that much of the growth occurs by the accumulation of clusters on the growing seed particles. The time scale for cluster diffusion indicates, however, that the clusters responsible for growth must be much smaller than the apparent fine structure of the product particles.

  6. A nanoscale temperature-dependent heterogeneous nucleation theory

    International Nuclear Information System (INIS)

    Cao, Y. Y.; Yang, G. W.

    2015-01-01

    Classical nucleation theory relies on the hypothetical equilibrium of the whole nucleation system, and neglects the thermal fluctuations of the surface; this is because the high entropic gains of the (thermodynamically extensive) surface would lead to multiple stable states. In fact, at the nanometer scale, the entropic gains of the surface are high enough to destroy the stability of the thermal equilibrium during nucleation, comparing with the whole system. We developed a temperature-dependent nucleation theory to elucidate the heterogeneous nucleation process, by considering the thermal fluctuations based on classical nucleation theory. It was found that the temperature not only affected the phase transformation, but also influenced the surface energy of the nuclei. With changes in the Gibbs free energy barrier, nucleation behaviors, such as the nucleation rate and the critical radius of the nuclei, showed temperature-dependent characteristics that were different from those predicted by classical nucleation theory. The temperature-dependent surface energy density of a nucleus was deduced based on our theoretical model. The agreement between the theoretical and experimental results suggested that the developed nucleation theory has the potential to contribute to the understanding and design of heterogeneous nucleation at the nanoscale

  7. Total glucosides of paeony attenuated functional maturation of dendritic cells via blocking TLR4/5 signaling in vivo.

    Science.gov (United States)

    Zhou, Zhou; Lin, Jinpiao; Huo, Rongfen; Huang, Wenkang; Zhang, Jian; Wang, Li; Sun, Yue; Shen, Baihua; Li, Ningli

    2012-11-01

    It is well known that dendritic cells (DCs) play a critical role in the initiation and development of an immune response. Inhibitory effect on DC maturation alters immune-mediated inflammatory reaction in vivo. Total glucosides of paeony (TGP) are active compounds extracted from the roots of Paeonia lactiflora and have been widely used to ameliorate inflammation in therapy for autoimmune diseases. However, whether TGP act on DC maturation remains unknown. In this study, we investigated the effect of TGP on DC maturation in ovalbumin (OVA) immunized mice. Ear inflammation was inhibited by TGP (150 mgkg(-1), i.p.×11 days) obviously. The antigen presenting capacity of DC derived from TGP-treated mice was arrested. Meanwhile, OVA specific T cell proliferation was inhibited. In addition, we found that maturation of DCs was decreased by TGP treatment. Furthermore, OVA specific T cell proliferation was rescued by the adoptive transfer of mature DCs (mDCs) into TGP treated OVA-challenged mice. The research on the mechanism showed that TGP significantly inhibited activation of TLR4/5 singling. All these results demonstrated that TGP inhibited DC maturation and function by selectively blocking TLR4/5 activation in vivo, which in turn leads to reduce immune-mediated inflammation in vivo, adding a novel mechanism and therapeutic target of TGP for inflammatory and autoimmune disease treatment. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Use of total lymphoid irradiation (TLI) in studies of the T cell dependence of autoantibody production in rheumatoid arthritis

    International Nuclear Information System (INIS)

    Tanay, A.; Strober, S.; Logue, G.L.; Schiffman, G.

    1984-01-01

    The effect of total lymphoid irradiation (TLI) on T cell-dependent and -independent humoral immune responses was studied in patients with intractable rheumatoid arthritis (RA). The serum levels of several autoantibodies and of antibodies to diphtheria (DT) and tetanus (TT) toxoids and to pneumococcal polysaccharide (PPS; 12 antigenic types) were studied before and after TLI. In addition, the patients were given a booster injection of DT and TT and a single injection of pneumococcal vaccine after radiotherapy. Antibody levels to DT and TT decreased about twofold after TLI and did not rise significantly after a booster injection. However, there was no reduction in antibody levels to PPS after TLI, and a significant rise in titers was observed after a single vaccination. The serum levels of rheumatoid factor (RF), anti-nuclear antibody (ANA), and granulocyte associated IgG rose slightly after TLI. Thus, the autoantibodies and antibodies to polysaccharides appear to be relatively independent of helper T cell function, which is markedly reduced after TLI. On the other hand, antibodies to protein antigens such as DT and TT appear to be more closely dependent upon T helper function in man, as has been reported in rodents. The findings suggest that T cell-independent autoantibody responses alone do not maintain the joint disease activity in RA, because improvement in joint disease after TLI has been reported

  9. Quantitative HRMAS proton total correlation spectroscopy applied to cultured melanoma cells treated by chloroethyl nitrosourea: demonstration of phospholipid metabolism alterations.

    Science.gov (United States)

    Morvan, Daniel; Demidem, Aicha; Papon, Janine; Madelmont, Jean Claude

    2003-02-01

    Recent NMR spectroscopy developments, such as high-resolution magic angle spinning (HRMAS) probes and correlation-enhanced 2D sequences, now allow improved investigations of phospholipid (Plp) metabolism. Using these modalities we previously demonstrated that a mouse-bearing melanoma tumor responded to chloroethyl nitrosourea (CENU) treatment in vivo by altering its Plp metabolism. The aims of the present study were to investigate whether HRMAS proton total correlation spectroscopy (TOCSY) could be used as a quantitative technique to probe Plp metabolism, and to determine the Plp metabolism response of cultured B16 melanoma cells to CENU treatment in vitro. The exploited TOCSY signals of Plp derivatives arose from scalar coupling among the protons of neighbor methylene groups within base headgroups (choline and ethanolamine). For strongly expressed Plp derivatives, TOCSY signals were compared to saturation recovery signals and demonstrated a linear relationship. HRMAS proton TOCSY was thus used to provide concentrations of Plp derivatives during long-term follow-up of CENU-treated cell cultures. Strong Plp metabolism alteration was observed in treated cultured cells in vitro involving a down-regulation of phosphocholine, and a dramatic and irreversible increase of phosphoethanolamine. These findings are discussed in relation to previous in vivo data, and to Plp metabolism enzymatic involvement. Copyright 2003 Wiley-Liss, Inc.

  10. Cellular and Molecular Mechanisms in Vascular Smooth Muscle Cells by which Total Saponin Extracted from Tribulus Terrestris Protects Against Artherosclerosis

    Directory of Open Access Journals (Sweden)

    Mengquan Li

    2013-11-01

    Full Text Available Background/Aims: Total saponin extracted from Tribulus terrestris (TSETT has been reported to protect against atherosclerosis. We here investigate the cellular and molecular mechanisms of TSETT underlying protection against atherosclerosis. Methods: Cell proliferation was measured with Methyl thiazolyl tetrazolium (MTT; Intracellular H2O2 was measured with DCFH-DA, a fluorescent dye; Intracellular free Ca2+ was measured with a confocal laser scanning microscopy; Genes expression was measured with gene array and real-time quantitative polymerase chain reaction (RT-PCR; Phosphorylation of extracellular signal-regulated kinase 1/2 (phospho-ERK1/2 was measured with cell-based enzyme-linked immunosorbent assay (ELISA and western blotting. Results: TSETT significantly suppressed the increase in cells proliferation induced by angiotensin II, significantly suppressed the increase in the intracellular production of H2O2 induced by angiotensin II, significantly inhibited the increase in intracellular free Ca2+ induced by H2O2, significantly inhibited the increase in phospho-ERK1/2 induced by angiotensin II; significantly inhibited the increase in mRNA expression of c-fos, c-jun and pkc-α induced by angiotensin II. Conclusion: These findings provide a new insight into the antiatherosclerotic properties of TSETT and provide a pharmacological basis for the clinical application of TSETT in anti-atherosclerosis.

  11. Cellular and molecular mechanisms in vascular smooth muscle cells by which total saponin extracted from Tribulus terrestris protects against artherosclerosis.

    Science.gov (United States)

    Li, Mengquan; Guan, Yue; Liu, Jiaqi; Zhai, Fengguo; Zhang, Xiuping; Guan, Lixin

    2013-01-01

    Total saponin extracted from Tribulus terrestris (TSETT) has been reported to protect against atherosclerosis. We here investigate the cellular and molecular mechanisms of TSETT underlying protection against atherosclerosis. Cell proliferation was measured with Methyl thiazolyl tetrazolium (MTT); Intracellular H2O2 was measured with DCFH-DA, a fluorescent dye; Intracellular free Ca(2+) was measured with a confocal laser scanning microscopy; Genes expression was measured with gene array and real-time quantitative polymerase chain reaction (RT-PCR); Phosphorylation of extracellular signal-regulated kinase 1/2 (phospho-ERK1/2) was measured with cell-based enzyme-linked immunosorbent assay (ELISA) and western blotting. TSETT significantly suppressed the increase in cells proliferation induced by angiotensin II, significantly suppressed the increase in the intracellular production of H2O2 induced by angiotensin II, significantly inhibited the increase in intracellular free Ca(2+) induced by H2O2, significantly inhibited the increase in phospho-ERK1/2 induced by angiotensin II; significantly inhibited the increase in mRNA expression of c-fos, c-jun and pkc-α induced by angiotensin II. These findings provide a new insight into the antiatherosclerotic properties of TSETT and provide a pharmacological basis for the clinical application of TSETT in anti-atherosclerosis. © 2013 S. Karger AG, Basel.

  12. The emergence of modern nucleation theory

    International Nuclear Information System (INIS)

    Cahn, J.W.

    1987-01-01

    A series of important papers by David Turnbull and his collaborators in the late 1940's and early 1950's laid the experimental and theoretical foundation of modern nucleation theory. The elegance, versatility, and generality of the phenomenological approach, coupled with brilliant and insightful experimental confirmation, sparked widespread application which continues today. Much of David Turnbull's subsequent work in other subjects grew directly or indirectly from this work

  13. Molecular-dynamics simulations of urea nucleation from aqueous solution.

    Science.gov (United States)

    Salvalaglio, Matteo; Perego, Claudio; Giberti, Federico; Mazzotti, Marco; Parrinello, Michele

    2015-01-06

    Despite its ubiquitous character and relevance in many branches of science and engineering, nucleation from solution remains elusive. In this framework, molecular simulations represent a powerful tool to provide insight into nucleation at the molecular scale. In this work, we combine theory and molecular simulations to describe urea nucleation from aqueous solution. Taking advantage of well-tempered metadynamics, we compute the free-energy change associated to the phase transition. We find that such a free-energy profile is characterized by significant finite-size effects that can, however, be accounted for. The description of the nucleation process emerging from our analysis differs from classical nucleation theory. Nucleation of crystal-like clusters is in fact preceded by large concentration fluctuations, indicating a predominant two-step process, whereby embryonic crystal nuclei emerge from dense, disordered urea clusters. Furthermore, in the early stages of nucleation, two different polymorphs are seen to compete.

  14. Molecular-dynamics simulations of urea nucleation from aqueous solution

    Science.gov (United States)

    Salvalaglio, Matteo; Perego, Claudio; Giberti, Federico; Mazzotti, Marco; Parrinello, Michele

    2015-01-01

    Despite its ubiquitous character and relevance in many branches of science and engineering, nucleation from solution remains elusive. In this framework, molecular simulations represent a powerful tool to provide insight into nucleation at the molecular scale. In this work, we combine theory and molecular simulations to describe urea nucleation from aqueous solution. Taking advantage of well-tempered metadynamics, we compute the free-energy change associated to the phase transition. We find that such a free-energy profile is characterized by significant finite-size effects that can, however, be accounted for. The description of the nucleation process emerging from our analysis differs from classical nucleation theory. Nucleation of crystal-like clusters is in fact preceded by large concentration fluctuations, indicating a predominant two-step process, whereby embryonic crystal nuclei emerge from dense, disordered urea clusters. Furthermore, in the early stages of nucleation, two different polymorphs are seen to compete. PMID:25492932

  15. Acoustic Effects in Classical Nucleation Theory

    Science.gov (United States)

    Baird, J. K.; Su, C.-H.

    2017-01-01

    The effect of sound wave oscillations on the rate of nucleation in a parent phase can be calculated by expanding the free energy of formation of a nucleus of the second phase in powers of the acoustic pressure. Since the period of sound wave oscillation is much shorter than the time scale for nucleation, the acoustic effect can be calculated as a time average of the free energy of formation of the nucleus. The leading non-zero term in the time average of the free energy is proportional to the square of the acoustic pressure. The Young-Laplace equation for the surface tension of the nucleus can be used to link the time average of the square of the pressure in the parent phase to its time average in the nucleus of the second phase. Due to the surface tension, the pressure in the nuclear phase is higher than the pressure in the parent phase. The effect is to lower the free energy of formation of the nucleus and increase the rate of nucleation.

  16. Systematic coarse-graining in nucleation theory

    Science.gov (United States)

    Schweizer, M.; Sagis, L. M. C.

    2015-08-01

    In this work, we show that the standard method to obtain nucleation rate-predictions with the aid of atomistic Monte Carlo simulations leads to nucleation rate predictions that deviate 3 - 5 orders of magnitude from the recent brute-force molecular dynamics simulations [Diemand et al., J. Chem. Phys. 139, 074309 (2013)] conducted in the experimental accessible supersaturation regime for Lennard-Jones argon. We argue that this is due to the truncated state space the literature mostly relies on, where the number of atoms in a nucleus is considered the only relevant order parameter. We here formulate the nonequilibrium statistical mechanics of nucleation in an extended state space, where the internal energy and momentum of the nuclei are additionally incorporated. We show that the extended model explains the lack in agreement between the molecular dynamics simulations by Diemand et al. and the truncated state space. We demonstrate additional benefits of using the extended state space; in particular, the definition of a nucleus temperature arises very naturally and can be shown without further approximation to obey the fluctuation law of McGraw and LaViolette. In addition, we illustrate that our theory conveniently allows to extend existing theories to richer sets of order parameters.

  17. Nucleation reactions during deformation and crystallization of metallic glass

    International Nuclear Information System (INIS)

    Perepezko, J.H.; Imhoff, S.D.; Chen, M.W.; Gonzalez, S.; Inoue, A.

    2012-01-01

    Highlights: ► New approach to the examination and analysis of shear band nucleation. ► Discovery of multiple shear band nucleation sites. ► Identification of a method of using transient kinetic behavior to provide a more realistic evaluation of the diffusivity that is relevant to nucleation. - Abstract: Nucleation reactions play a central role in the synthesis of both bulk metallic glasses and nanostructured materials. For nanostructured materials it is necessary to promote a high nucleation density without significant growth or coarsening. Beyond crystallization reactions nucleation of shear bands is critical for promoting a homogeneous flow and useful ductility for structural applications of bulk metallic glass. The study and analysis of nucleation reactions for these different situations requires a consideration of the stochastic nature of nucleation, the influence of heterogeneous sites, and the controlling transport properties. For shear band nucleation, the stochastic nature can be effectively probed by instrumented nanoindentation tests. The analysis of a statistically significant number of measurements of the first pop-in shear band nucleation events reveals at least two main nucleation sites. In nanostructured composites, the initial nucleation stage is influenced by transient effects as reflected in the delay time prior to steady state nucleation and by heterogeneous nucleation sites that are related to medium range order regions in Al-base amorphous alloys. Moreover, the early growth characteristics are linked to the maximum achievable particle density. The new developments and insight on the fundamental understanding of nanostructure reaction mechanisms offer valuable guidance for control of nanoscale microstructures and for promoting ductile deformation behavior.

  18. Urinary total arsenic and 8-hydroxydeoxyguanosine are associated with renal cell carcinoma in an area without obvious arsenic exposure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao-Yuan [Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Department of Urology, National Taiwan University Hospital, College of Medicine National Taiwan University, Taipei, Taiwan (China); Su, Chien-Tien [Department of Family Medicine, Taipei Medical University Hospital, Taipei, Taiwan (China); Chung, Chi-Jung [Department of Health Risk Management, College of Public Health, China Medical University, Taichung, Taiwan (China); Department of Medical Research, China Medical University Hospital, Taichung, Taiwan (China); Pu, Yeong-Shiau [Department of Urology, National Taiwan University Hospital, College of Medicine National Taiwan University, Taipei, Taiwan (China); Chu, Jan-Show [Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Department of Pathology, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Yang, Hsiu-Yuan [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Wu, Chia-Chang [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Department of Urology, Taipei Medical Universtiy-Shuang Ho Hospital, Taipei, Taiwan (China); Hsueh, Yu-Mei, E-mail: ymhsueh@tmu.edu.tw [Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China)

    2012-08-01

    8-Hydroxydeoxyguanosine (8-OHdG) is one of the most reliable and abundant markers of DNA damage. The study was designed to explore the relationship between urinary 8-OHdG and renal cell carcinoma (RCC) and to investigate whether individuals with a high level of 8-OHdG would have a modified odds ratio (OR) of arsenic-related RCC. This case–control study was conducted with 132 RCC patients and 245 age- and sex-matched controls from a hospital-based pool between November 2006 and May 2009. Pathological verification of RCC was completed by image-guided biopsy or surgical resection of renal tumors. Urinary 8-OHdG levels were determined using liquid chromatography with tandem mass spectrometry (LC–MS/MS). Concentrations of urinary arsenic species, including inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Level of urinary 8-OHdG was significantly associated with the OR of RCC in a dose–response relationship after multivariate adjustment. Urinary 8-OHdG was significantly related to urinary total arsenic. The greatest OR (3.50) was seen in the individuals with high urinary 8-OHdG and high urinary total arsenic. A trend test indicated that the OR of RCC was increased with one of these factors and was further increased with both (p = 0.002). In conclusion, higher urinary 8-OHdG was a strong predictor of the RCC. High levels of 8-OHdG combined with urinary total arsenic might be indicative of arsenic-induced RCC. -- Highlights: ► Urinary 8-OHdG was significantly related to urinary total arsenic. ► Higher urinary 8-OHdG was a strong predictor of RCC risk. ► Urinary 8-OHdG may modify arsenic related RCC risk.

  19. Total-body irradiation - role and indications. Results from the German Registry for Stem Cell Transplantation (DRST)

    International Nuclear Information System (INIS)

    Heinzelmann, F.; Bamberg, M.; Belka, C.; Ottinger, H.; Mueller, C.H.; Allgaier, S.; Faul, C.

    2006-01-01

    Background and purpose: total-body irradiation (TBI) is a key part of the conditioning regimen before hematopoietic stem cell transplantation (HSCT). The exact role of TBI as part of the conditioning regimen is largely unclear. In order to determine the relevance of TBI, the status of TBI utilization was analyzed on the basis of a nationwide registry. Material and methods: 14,371 patients (1998-2002) documented in the German Stem Cell Transplantation Registry (DRST) were analyzed regarding TBI utilization prior to autologous or allogeneic transplantation, underlying disorder, type of donor, stem cell source, and size of the treatment center. Results: for autologous HSCT ∝10% of the patients (873/8,167) received TBI, with chronic lymphocytic leukemia (CLL, ∝80%, 171/214) and low-grade non-Hodgkin's lymphoma (l-NHL, ∝35%, 330/929) being the most important disorders. In the allogeneic setting 50% of the patients (2,399/4,904) received TBI, with acute lymphocytic leukemia (ALL, 85%, 794/930), acute myeloid leukemia (AML, 45%, 662/1,487) and chronic myeloid leukemia (CML, 49%, 561/1,156) being the key indications. The type of donor, stem cell source and center size did not strongly influence the use of TBI. Conclusion: TBI has only a limited role for the conditioning prior to autologous HCST. For allogeneic HSCT TBI is widely accepted with no major changes over the observation time. The use of TBI is generally accepted for ALL, whereas approximately half of the patients with CML or AML received TBI. Although a considerably large database was analyzed, no clear determinants for the use of TBI could be distinguished. (orig.)

  20. Total-body irradiation - role and indications. Results from the German Registry for Stem Cell Transplantation (DRST)

    Energy Technology Data Exchange (ETDEWEB)

    Heinzelmann, F.; Bamberg, M.; Belka, C. [Dept. of Radiation Oncology, Univ. of Tuebingen (Germany); Ottinger, H. [German Registry for Stem Cell Transplantation (DRST) Secretary, Univ. of Essen (Germany); Mueller, C.H.; Allgaier, S. [DRST Datacenter, DRK Bloodbank Center Ulm (Germany); Faul, C. [Dept. of Internal Medicine II, Univ. of Tuebingen (Germany)

    2006-04-15

    Background and purpose: total-body irradiation (TBI) is a key part of the conditioning regimen before hematopoietic stem cell transplantation (HSCT). The exact role of TBI as part of the conditioning regimen is largely unclear. In order to determine the relevance of TBI, the status of TBI utilization was analyzed on the basis of a nationwide registry. Material and methods: 14,371 patients (1998-2002) documented in the German Stem Cell Transplantation Registry (DRST) were analyzed regarding TBI utilization prior to autologous or allogeneic transplantation, underlying disorder, type of donor, stem cell source, and size of the treatment center. Results: for autologous HSCT {proportional_to}10% of the patients (873/8,167) received TBI, with chronic lymphocytic leukemia (CLL, {proportional_to}80%, 171/214) and low-grade non-Hodgkin's lymphoma (l-NHL, {proportional_to}35%, 330/929) being the most important disorders. In the allogeneic setting 50% of the patients (2,399/4,904) received TBI, with acute lymphocytic leukemia (ALL, 85%, 794/930), acute myeloid leukemia (AML, 45%, 662/1,487) and chronic myeloid leukemia (CML, 49%, 561/1,156) being the key indications. The type of donor, stem cell source and center size did not strongly influence the use of TBI. Conclusion: TBI has only a limited role for the conditioning prior to autologous HCST. For allogeneic HSCT TBI is widely accepted with no major changes over the observation time. The use of TBI is generally accepted for ALL, whereas approximately half of the patients with CML or AML received TBI. Although a considerably large database was analyzed, no clear determinants for the use of TBI could be distinguished. (orig.)

  1. Clonorchis sinensis-derived total protein attenuates airway inflammation in murine asthma model by inducing regulatory T cells and modulating dendritic cell functions

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Young-Il [Div. of Malaria and Parasitic Diseases, Korea Centers for Disease Control and Prevention, Osong (Korea, Republic of); Kim, Seung Hyun [Div. of AIDS, National Institute of Health, Korea Centers for Disease Control and Prevention, Osong (Korea, Republic of); Ju, Jung Won; Cho, Shin Hyeong; Lee, Won Ja [Div. of Malaria and Parasitic Diseases, Korea Centers for Disease Control and Prevention, Osong (Korea, Republic of); Park, Jin Wook; Park, Yeong-Min [Dept. of Microbiology and Immunology, College of Medicine, Pusan National University, Yang-San (Korea, Republic of); Lee, Sang Eun, E-mail: ondalgl@cdc.go.kr [Div. of Malaria and Parasitic Diseases, Korea Centers for Disease Control and Prevention, Osong (Korea, Republic of)

    2011-04-22

    Highlights: {yields} Treatment with Clonorchis sinensis-derived total protein attenuates OVA-induced airway inflammation and AHR to methacholine. {yields} Induction of CD4{sup +}CD25{sup +}Foxp3{sup +} T cells and IL-10 along with suppression of splenocyte proliferation by C. sinensis-derived total protein. {yields} C. sinensis-derived total protein interferes with the expression of co-stimulatory molecules in DCs. -- Abstract: Asthma is characterized by Th2-mediated inflammation, resulting in airway hyperresponsiveness (AHR) through airway remodeling. Recent epidemiological and experimental reports have suggested an inverse relationship between the development of allergy and helminth infections. Infection by Clonorchis sinensis, a liver fluke that resides in the bile duct of humans, is endemic predominantly in Asia including Korea and China. Using a murine model for asthma, we investigated the effects of C. sinensis-derived total protein (Cs-TP) on allergen-induced airway inflammation and the mechanism underlying the protective effects of Cs-TP administration on asthma. Treatment with Cs-TP attenuated OVA-induced airway inflammation and methacholine-induced AHR, as well as eosinophilia development, lymphocyte infiltration into the lung, and goblet cell metaplasia. This protective effect of Cs-TP is associated with markedly reduced OVA-specific IgE and Th1/Th2 cytokine production. Moreover, Cs-TP increased the number of CD4{sup +}CD25{sup +}Foxp3{sup +} regulatory T (Treg) cells as well as their suppressive activity. In fact, proliferation of OVA-restimulated splenocytes was suppressed significantly. Cs-TP also inhibited the expression of such co-stimulatory molecules as CD80, CD86, and CD40 in LPS- or OVA-stimulated dendritic cells (DCs), suggesting that Cs-TP could interfere with the capacity of airway DCs to prime naive T cells. These data demonstrate the capacity of C. sinensis to ameliorate allergic asthma and broaden our understanding of the paradoxical

  2. Total pleurectomy as the surgical treatment for recurrent secondary spontaneous pneumothorax in a child with severe pulmonary Langerhans cells histiocytosis.

    Science.gov (United States)

    Abdul Aziz, Dayang Anita; Abdul Rahman, Nur Afdzillah; Tang, Swee Fong; Abdul Latif, Hasniah; Zaki, Faizah Mohd; Annuar, Zulfiqar Mohd; Alias, Hamidah; Abdul Latiff, Zarina

    2011-12-01

    Pulmonary Langerhans cell histiocytosis (LCH) in children is more extensive and is a rare cause of spontaneous secondary pneumothorax (SSP) which tends to be recurrent and refractory to conventional treatment. Its occurrence in paediatric patients posed great challenge to the choice of surgical management. Surgery in the form of pleurodesis is only considered if SSP does not improve after chemotherapy and after considering all relevant risk and benefits of surgery to patients. Chemical pleurodesis will not give the expected effect to eradicate SSP in this patient. Therefore mechanical pleurodesis is the treatment of choice. There are various techniques to perform mechanical pleurodesis; from pleural abrasion to pleurectomy. In the authors' experience, bilateral total pleurectomy provided the best outcome for this 9-year-old patient with persistent respiratory distress from SSP due to extensive pulmonary LCH.

  3. Interaction of the nucleation phenomena at adjacent sites in nucleate boiling

    International Nuclear Information System (INIS)

    Sultan, M.; Judd, R.L.

    1983-01-01

    The present investigation is an original study in nucleate pool boiling heat transfer combining theory and experiment in which water boiling at atmospheric pressure on a single copper surface at two different levels of heat and different levels of subcooling was studied. Cross spectral analysis of the signals generated by the emission of bubbles at adjacent nucleation sites was used to determine the relationship of the time elapsed between the start of bubble growth at the two neighbouring active sites with the distance separating them. The experimental results obtained indicated that for the lower level of heat flux at three different levels of subcooling, the elapsed time and distance were directly related. Theoretical predictions of a temperature disturbance propagating through the heating surface in the radial direction gave good agreement with the experimental findings, suggesting that this is the mechanism responsible for the activation of the surrounding nucleation sites

  4. The Total Body Irradiation Schedule Affects Acute Leukemia Relapse After Matched T Cell–Depleted Hematopoietic Stem Cell Transplantation

    International Nuclear Information System (INIS)

    Aristei, Cynthia; Carotti, Alessandra; Palazzari, Elisa; Amico, Lucia; Ruggeri, Loredana; Perrucci, Elisabetta; Falcinelli, Lorenzo; Lancellotta, Valentina; Palumbo, Isabella; Falzetti, Franca; Aversa, Franco; Merluzzi, Mara; Velardi, Andrea; Martelli, Massimo Fabrizio

    2016-01-01

    Purpose: We sought to determine whether the total body irradiation (TBI) schedule affected outcome in patients with acute leukemia in complete remission who received T cell–depleted allogeneic hematopoietic stem cell transplantation from HLA identical siblings. Methods and Materials: The study recruited 55 patients (median age, 48 years; age range, 20-66 years; 30 men and 25 women; 34 with acute myeloid leukemia and 21 with acute lymphoid leukemia). Hyperfractionated TBI (HTBI) (1.2 Gy thrice daily for 4 days [for a total dose of 14.4 Gy] from day −12 to day −9) was administered to 29 patients. Single-dose TBI (STBI) (8 Gy, at a median dose rate of 10.7 cGy/min on day −9) was given to 26 patients. Results: All patients achieved primary, sustained engraftment with full donor-type chimerism. At 10 years, the overall cumulative incidence of transplant-related mortality was 11% (SE, ±0.1%). It was 7% (SE, ±0.2%) after HTBI and 15% (SE, ±0.5%) after STBI (P=.3). The overall cumulative incidence of relapse was 33% (SE, ±0.5). It was 13% (SE, ±0.5%) after HTBI and 46% (SE, ±1%) after STBI (P=.02). The overall probability of disease-free survival (DFS) was 59% (SE, ±7%). It was 67% (SE, ±0.84%) after HTBI and 37% (SE, ±1.4%) after STBI (P=.01). Multivariate analyses showed the TBI schedule was the only risk factor that significantly affected relapse and DFS (P=.01 and P=.03, respectively). Conclusions: In patients with acute leukemia, HTBI is more efficacious than STBI in eradicating minimal residual disease after HLA-matched T cell–depleted hematopoietic stem cell transplantation, thus affecting DFS.

  5. The Total Body Irradiation Schedule Affects Acute Leukemia Relapse After Matched T Cell–Depleted Hematopoietic Stem Cell Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Aristei, Cynthia, E-mail: cynthia.aristei@unipg.it [Radiation Oncology Section, Department of Surgery and Biomedical Sciences, University of Perugia and Perugia General Hospital, Perugia (Italy); Carotti, Alessandra [Division of Hematology and Clinical Immunology and Bone Marrow Transplant Program, Department of Medicine, Perugia General Hospital and University, Perugia (Italy); Palazzari, Elisa [Radiation Oncology Section, University of Perugia, Perugia (Italy); Amico, Lucia; Ruggeri, Loredana [Division of Hematology and Clinical Immunology and Bone Marrow Transplant Program, Department of Medicine, Perugia General Hospital and University, Perugia (Italy); Perrucci, Elisabetta; Falcinelli, Lorenzo [Radiation Oncology Division, Perugia General Hospital, Perugia (Italy); Lancellotta, Valentina [Radiation Oncology Section, University of Perugia, Perugia (Italy); Palumbo, Isabella [Radiation Oncology Section, Department of Surgery and Biomedical Sciences, University of Perugia and Perugia General Hospital, Perugia (Italy); Falzetti, Franca [Division of Hematology and Clinical Immunology and Bone Marrow Transplant Program, Department of Medicine, Perugia General Hospital and University, Perugia (Italy); Aversa, Franco [Hematology and Bone Marrow Transplant Unit, Department of Clinical and Experimental Medicine, Parma General Hospital and University, Parma (Italy); Merluzzi, Mara; Velardi, Andrea; Martelli, Massimo Fabrizio [Division of Hematology and Clinical Immunology and Bone Marrow Transplant Program, Department of Medicine, Perugia General Hospital and University, Perugia (Italy)

    2016-11-15

    Purpose: We sought to determine whether the total body irradiation (TBI) schedule affected outcome in patients with acute leukemia in complete remission who received T cell–depleted allogeneic hematopoietic stem cell transplantation from HLA identical siblings. Methods and Materials: The study recruited 55 patients (median age, 48 years; age range, 20-66 years; 30 men and 25 women; 34 with acute myeloid leukemia and 21 with acute lymphoid leukemia). Hyperfractionated TBI (HTBI) (1.2 Gy thrice daily for 4 days [for a total dose of 14.4 Gy] from day −12 to day −9) was administered to 29 patients. Single-dose TBI (STBI) (8 Gy, at a median dose rate of 10.7 cGy/min on day −9) was given to 26 patients. Results: All patients achieved primary, sustained engraftment with full donor-type chimerism. At 10 years, the overall cumulative incidence of transplant-related mortality was 11% (SE, ±0.1%). It was 7% (SE, ±0.2%) after HTBI and 15% (SE, ±0.5%) after STBI (P=.3). The overall cumulative incidence of relapse was 33% (SE, ±0.5). It was 13% (SE, ±0.5%) after HTBI and 46% (SE, ±1%) after STBI (P=.02). The overall probability of disease-free survival (DFS) was 59% (SE, ±7%). It was 67% (SE, ±0.84%) after HTBI and 37% (SE, ±1.4%) after STBI (P=.01). Multivariate analyses showed the TBI schedule was the only risk factor that significantly affected relapse and DFS (P=.01 and P=.03, respectively). Conclusions: In patients with acute leukemia, HTBI is more efficacious than STBI in eradicating minimal residual disease after HLA-matched T cell–depleted hematopoietic stem cell transplantation, thus affecting DFS.

  6. Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation?

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2015-12-01

    Full Text Available Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3 reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with total gaseous mercury (TGM were found that, together with other data, suggest a mercury-driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (∼ 1.5 ng m−3 and ≥ 600 W m−2, respectively, such as those observed in the Antarctic sea ice boundary layer in this study or in the global free troposphere, particularly in the Northern Hemisphere.

  7. Role of Dynamic Nucleation at Moving Boundaries in Phase and Microstructure Selection

    Science.gov (United States)

    Karma, Alain; Trivedi, Rohit

    1999-01-01

    Solidification microstructures that form under steady-state growth conditions (cells, dendrites, regular eutectics, etc.) are reasonably well understood in comparison to other, more complex microstructures, which form under intrinsically non-steady-state growth conditions due to the competition between the nucleation and growth of several phases. Some important practical examples in this latter class include microstructures forming in peritectic systems in highly undercooled droplets, and in strip cast stainless steels. Prediction of phase and microstructure selection in these systems has been traditionally based on (1) heterogeneous nucleation on a static interface, and (2) comparing the relative growth rate of different phase/microstructures under steady-state growth conditions. The formation of new phases, however, occurs via nucleation on, or ahead of, a moving boundary. In addition, the actual selection process is controlled by a complex interaction between the nucleation process and the growth competition between the nuclei and the pre-existing phase under non-steady-state conditions. As a result, it is often difficult to predict which microstructure will form and which phases will be selected under prescribed processing conditions. This research addresses this critical role of nucleation at moving boundaries in the selection of phases and solidification microstructures through quantitative experiments and numerical modeling in peritectic systems. In order to create a well characterized system in which to study this problem, we focus on the directional solidification of hypo- and hyper-peritectic alloys in the two-phase region, imposing a large enough ratio of temperature gradient/growth rate (G/V(sub p)) to suppress the morphological instability of both the parent (alpha) and peritectic (Beta) phases, i.e. each phase alone would grow as a planar front. Our combined experimental and theoretical results show that, already in this simplified case, the growth

  8. Effects of shear flow on phase nucleation and crystallization.

    Science.gov (United States)

    Mura, Federica; Zaccone, Alessio

    2016-04-01

    Classical nucleation theory offers a good framework for understanding the common features of new phase formation processes in metastable homogeneous media at rest. However, nucleation processes in liquids are ubiquitously affected by hydrodynamic flow, and there is no satisfactory understanding of whether shear promotes or slows down the nucleation process. We developed a classical nucleation theory for sheared systems starting from the molecular level of the Becker-Doering master kinetic equation and we analytically derived a closed-form expression for the nucleation rate. The theory accounts for the effect of flow-mediated transport of molecules to the nucleus of the new phase, as well as for the mechanical deformation imparted to the nucleus by the flow field. The competition between flow-induced molecular transport, which accelerates nucleation, and flow-induced nucleus straining, which lowers the nucleation rate by increasing the nucleation energy barrier, gives rise to a marked nonmonotonic dependence of the nucleation rate on the shear rate. The theory predicts an optimal shear rate at which the nucleation rate is one order of magnitude larger than in the absence of flow.

  9. Recent progress on understanding the mechanisms of amyloid nucleation.

    Science.gov (United States)

    Chatani, Eri; Yamamoto, Naoki

    2018-04-01

    Amyloid fibrils are supramolecular protein assemblies with a fibrous morphology and cross-β structure. The formation of amyloid fibrils typically follows a nucleation-dependent polymerization mechanism, in which a one-step nucleation scheme has widely been accepted. However, a variety of oligomers have been identified in early stages of fibrillation, and a nucleated conformational conversion (NCC) mechanism, in which oligomers serve as a precursor of amyloid nucleation and convert to amyloid nuclei, has been proposed. This development has raised the need to consider more complicated multi-step nucleation processes in addition to the simplest one-step process, and evidence for the direct involvement of oligomers as nucleation precursors has been obtained both experimentally and theoretically. Interestingly, the NCC mechanism has some analogy with the two-step nucleation mechanism proposed for inorganic and organic crystals and protein crystals, although a more dramatic conformational conversion of proteins should be considered in amyloid nucleation. Clarifying the properties of the nucleation precursors of amyloid fibrils in detail, in comparison with those of crystals, will allow a better understanding of the nucleation of amyloid fibrils and pave the way to develop techniques to regulate it.

  10. Rate of Homogenous Nucleation of Ice in Supercooled Water.

    Science.gov (United States)

    Atkinson, James D; Murray, Benjamin J; O'Sullivan, Daniel

    2016-08-25

    The homogeneous freezing of water is of fundamental importance to a number of fields, including that of cloud formation. However, there is considerable scatter in homogeneous nucleation rate coefficients reported in the literature. Using a cold stage droplet system designed to minimize uncertainties in temperature measurements, we examined the freezing of over 1500 pure water droplets with diameters between 4 and 24 μm. Under the assumption that nucleation occurs within the bulk of the droplet, nucleation rate coefficients fall within the spread of literature data and are in good agreement with a subset of more recent measurements. To quantify the relative importance of surface and volume nucleation in our experiments, where droplets are supported by a hydrophobic surface and surrounded by oil, comparison of droplets with different surface area to volume ratios was performed. From our experiments it is shown that in droplets larger than 6 μm diameter (between 234.6 and 236.5 K), nucleation in the interior is more important than nucleation at the surface. At smaller sizes we cannot rule out a significant contribution of surface nucleation, and in order to further constrain surface nucleation, experiments with smaller droplets are necessary. Nevertheless, in our experiments, it is dominantly volume nucleation controlling the observed nucleation rate.

  11. A review of phosphate mineral nucleation in biology and geobiology.

    Science.gov (United States)

    Omelon, Sidney; Ariganello, Marianne; Bonucci, Ermanno; Grynpas, Marc; Nanci, Antonio

    2013-10-01

    Relationships between geological phosphorite deposition and biological apatite nucleation have often been overlooked. However, similarities in biological apatite and phosphorite mineralogy suggest that their chemical formation mechanisms may be similar. This review serves to draw parallels between two newly described phosphorite mineralization processes, and proposes a similar novel mechanism for biologically controlled apatite mineral nucleation. This mechanism integrates polyphosphate biochemistry with crystal nucleation theory. Recently, the roles of polyphosphates in the nucleation of marine phosphorites were discovered. Marine bacteria and diatoms have been shown to store and concentrate inorganic phosphate (Pi) as amorphous, polyphosphate granules. Subsequent release of these P reserves into the local marine environment as Pi results in biologically induced phosphorite nucleation. Pi storage and release through an intracellular polyphosphate intermediate may also occur in mineralizing oral bacteria. Polyphosphates may be associated with biologically controlled apatite nucleation within vertebrates and invertebrates. Historically, biological apatite nucleation has been attributed to either a biochemical increase in local Pi concentration or matrix-mediated apatite nucleation control. This review proposes a mechanism that integrates both theories. Intracellular and extracellular amorphous granules, rich in both calcium and phosphorus, have been observed in apatite-biomineralizing vertebrates, protists, and atremate brachiopods. These granules may represent stores of calcium-polyphosphate. Not unlike phosphorite nucleation by bacteria and diatoms, polyphosphate depolymerization to Pi would be controlled by phosphatase activity. Enzymatic polyphosphate depolymerization would increase apatite saturation to the level required for mineral nucleation, while matrix proteins would simultaneously control the progression of new biological apatite formation.

  12. Chitin hydrolysis assisted by cell wall degrading enzymes immobilized of Thichoderma asperellum on totally cinnamoylated D-sorbitol beads

    International Nuclear Information System (INIS)

    Fernandes, Kátia F.; Cortijo-Triviño, David; Batista, Karla A.; Ulhoa, Cirano J.; García-Ruiz, Pedro A.

    2013-01-01

    In this study, cell wall degrading enzymes produced by Thrichoderma asperellum (TCWDE) were immobilized on totally cinnamoylated D-sorbitol (TCNSO) beads and used for chitin hydrolysis. In order to optimize immobilization efficiency, the reaction time was varied from 2 to 12 h and reactions were conducted in the presence or absence of Na 2 SO 4 . Immobilized enzymes were analysed concerning to thermal and operational stability. Immobilization in presence of Na 2 SO 4 was 54% more efficient than immobilization in absence of salt. After optimization, 32% of the total enzyme offered was immobilized, with 100% of bounding efficiency, measured as the relation between protein and enzyme immobilized. Free and TCNSO–TCWDE presented very similar kinetics with maximum hydrolysis reached at 90 min of reaction. Thermal stability of both free and TCNSO–TCWDE was similar, with losses in activity after 55 °C. Moreover, free and TCNSO–TCWDE retained 100% activity after 3 h incubation at 55 °C. TCNSO–TCWDE were used in a bath-wise reactor during 14 cycles, producing 1825 μg of N-acetylglucosamine (NAG) maintaining 83% of initial activity. - Highlights: • TCWDE immobilized on TCNSO, a support with highly hydrophobic character • New immobilization strategy for immobilization on a hydrophobic support • TCNSO–TCWDE were retained during washes and during incubation at 55 °C for 3 h

  13. Chitin hydrolysis assisted by cell wall degrading enzymes immobilized of Thichoderma asperellum on totally cinnamoylated D-sorbitol beads

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Kátia F., E-mail: katia@icb.ufg.br [Departamento de Bioquímica e Biologia Molecular, Instituo de Ciências Biológicas, Universidade Federal de Goiás, Cx. Postal 131, 74001-970 Goiânia, GO (Brazil); Grupo de Química de Carbohidratos y Biotecnología de Alimentos (QCBA), Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, E-30100 Espinardo, Murcia (Spain); Cortijo-Triviño, David [Grupo de Química de Carbohidratos y Biotecnología de Alimentos (QCBA), Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, E-30100 Espinardo, Murcia (Spain); Batista, Karla A.; Ulhoa, Cirano J. [Departamento de Bioquímica e Biologia Molecular, Instituo de Ciências Biológicas, Universidade Federal de Goiás, Cx. Postal 131, 74001-970 Goiânia, GO (Brazil); García-Ruiz, Pedro A. [Grupo de Química de Carbohidratos y Biotecnología de Alimentos (QCBA), Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, E-30100 Espinardo, Murcia (Spain)

    2013-07-01

    In this study, cell wall degrading enzymes produced by Thrichoderma asperellum (TCWDE) were immobilized on totally cinnamoylated D-sorbitol (TCNSO) beads and used for chitin hydrolysis. In order to optimize immobilization efficiency, the reaction time was varied from 2 to 12 h and reactions were conducted in the presence or absence of Na{sub 2}SO{sub 4}. Immobilized enzymes were analysed concerning to thermal and operational stability. Immobilization in presence of Na{sub 2}SO{sub 4} was 54% more efficient than immobilization in absence of salt. After optimization, 32% of the total enzyme offered was immobilized, with 100% of bounding efficiency, measured as the relation between protein and enzyme immobilized. Free and TCNSO–TCWDE presented very similar kinetics with maximum hydrolysis reached at 90 min of reaction. Thermal stability of both free and TCNSO–TCWDE was similar, with losses in activity after 55 °C. Moreover, free and TCNSO–TCWDE retained 100% activity after 3 h incubation at 55 °C. TCNSO–TCWDE were used in a bath-wise reactor during 14 cycles, producing 1825 μg of N-acetylglucosamine (NAG) maintaining 83% of initial activity. - Highlights: • TCWDE immobilized on TCNSO, a support with highly hydrophobic character • New immobilization strategy for immobilization on a hydrophobic support • TCNSO–TCWDE were retained during washes and during incubation at 55 °C for 3 h.

  14. Long-term renal toxicity in children following fractionated total-body irradiation (TBI) before allogeneic stem cell transplantation (SCT)

    International Nuclear Information System (INIS)

    Gerstein, Johanna; Meyer, Andreas; Fruehauf, Joerg; Karstens, Johann H.; Bremer, Michael; Sykora, Karl-Walter

    2009-01-01

    Purpose: to retrospectively assess the incidence and time course of renal dysfunction in children (≤ 16 years) following total-body irradiation (TBI) before allogeneic stem cell transplantation (SCT). Patients and methods: between 1986 and 2003, 92 children (median age, 11 years; range, 3-16 years) underwent TBI before allogeneic SCT. 43 of them had a minimum follow-up of 12 months (median, 51 months; range, 12-186 months) and were included into this analysis. Conditioning regimen included chemotherapy and fractionated TBI with 12 Gy (n = 26) or 11.1 Gy (n = 17). In one patient, renal dose was limited to 10 Gy by customized renal shielding due to known nephropathy prior to SCt. Renal dysfunction was defined as an increase of serum creatinine > 1.25 times the upper limit of age-dependent normal. Results: twelve children (28%) experienced an episode of renal dysfunction after a median of 2 months (range, 1-10 months) following SCT. In all but one patient renal dysfunction was transient and resolved after a median of 8 months (range, 3-16 months). One single patient developed persistent renal dysfunction with onset at 10 months after SCT. None of these patients required dialysis. The actuarial 3-year freedom from persistent renal toxicity for children surviving > 12 months after SCt was 97.3%. Conclusion: the incidence of persistent renal dysfunction after fractionated TBI with total doses ≤ 12 Gy was very low in this analysis. (orig.)

  15. Atmospheric nucleation: highlights of the EUCAARI project and future directions

    Directory of Open Access Journals (Sweden)

    V.-M. Kerminen

    2010-11-01

    Full Text Available Within the project EUCAARI (European Integrated project on Aerosol Cloud Climate and Air Quality interactions, atmospheric nucleation was studied by (i developing and testing new air ion and cluster spectrometers, (ii conducting homogeneous nucleation experiments for sulphate and organic systems in the laboratory, (iii investigating atmospheric nucleation mechanism under field conditions, and (iv applying new theoretical and modelling tools for data interpretation and development of parameterisations. The current paper provides a synthesis of the obtained results and identifies the remaining major knowledge gaps related to atmospheric nucleation. The most important technical achievement of the project was the development of new instruments for measuring sub-3 nm particle populations, along with the extensive application of these instruments in both the laboratory and the field. All the results obtained during EUCAARI indicate that sulphuric acid plays a central role in atmospheric nucleation. However, also vapours other than sulphuric acid are needed to explain the nucleation and the subsequent growth processes, at least in continental boundary layers. Candidate vapours in this respect are some organic compounds, ammonia, and especially amines. Both our field and laboratory data demonstrate that the nucleation rate scales to the first or second power of the nucleating vapour concentration(s. This agrees with the few earlier field observations, but is in stark contrast with classical thermodynamic nucleation theories. The average formation rates of 2-nm particles were found to vary by almost two orders of magnitude between the different EUCAARI sites, whereas the formation rates of charged 2-nm particles varied very little between the sites. Overall, our observations are indicative of frequent, yet moderate, ion-induced nucleation usually outweighed by much stronger neutral nucleation events in the continental lower troposphere. The most concrete

  16. Evaluation of Partial and Total Splenectomy in Children with Sickle Cell Disease Using an Internet-Based Registry

    Science.gov (United States)

    Mouttalib, Sofia; Rice, Henry E.; Snyder, Denise; Levens, Justin S.; Reiter, Audra; Soler, Pauline; Rothman, Jennifer A.; Thornburg, Courtney D.

    2011-01-01

    Background Clinical outcomes of children with sickle cell disease (SCD) who undergo total or partial splenectomy are poorly defined. The purpose of this retrospective study was to initiate an internet-based registry to facilitate analysis of clinical outcomes for these children. We hypothesized that both surgical procedures would be well tolerated and would eliminate risk of splenic sequestration. Methods We developed a web-based registry using the Research Electronic Data Capture (REDCap) platform. Children were included if they had SCD and underwent total splenectomy (TS) or partial splenectomy (PS) between 2003 to 2010. Clinical outcomes were compared between cohorts, with follow-up to one year. Results Twenty-four children were included, total splenectomy (n=15) and partial splenectomy (n=9). There were no differences in surgical time or intraoperative blood loss. The length of stay was longer after PS (4.1±1.7 days) compared to TS, (2.4±1.2 days, p=0.02). Within 30 days of surgery, 2 (20%) patients had acute chest syndrome following TS and 2 (15%) patients had acute chest syndrome after PS. During one year follow-up, no patient in either cohort had recurrent splenic sequestration, venous thrombosis or overwhelming post-splenectomy sepsis. All children who were transfused preoperatively to prevent recurrent splenic sequestration successfully discontinued transfusions. Conclusions Both TS and PS result in favorable hematologic outcomes and low risk of adverse events for children with SCD. A REDCap based registry may facilitate data entry and analysis of clinical outcomes to allow for comparison between different types of splenectomy. PMID:22238140

  17. Comparison of total body irradiation-based or non-total body irradiation-based conditioning regimens for allogeneic stem cell transplantation in pediatric leukemia patients

    Directory of Open Access Journals (Sweden)

    Sang Jeong Kim

    2010-04-01

    Full Text Available Purpose : This study aims to compare the outcome of total body irradiation (TBI- or non-TBI-containing conditioning regimens for leukemia in children. Methods : We retrospectively evaluated 77 children conditioned with TBI (n=40 or non-TBI (n=37 regimens, transplanted at Chonnam National University Hospital between January 1996 and December 2007. The type of transplantation, disease status at the time of transplant, conditioning regimen, engraftment kinetics, development of graft-versus-host disease (GVHD, complications, cause of deaths, overall survival (OS, and event-free survival (EFS were compared between the 2 groups. Results : Among 34 patients with acute lymphoblastic leukemia (ALL, 28 (82.4% were in the TBI group, while 72.7% (24/33 of patients with myeloid leukemia were in the non-TBI group. Although the 5-year EFS of the 2 groups was similar for all patients (62% vs 63%, the TBI group showed a better 5-year EFS than the non-TBI group when only ALL patients were analyzed (65% vs 17%; P =0.005. In acute myelogenous leukemia patients, the non-TBI group had better survival tendency (73% vs 38%; P=0.089. The incidence of GVHD, engraftment, survival, cause of death, and late complications was not different between the 2 groups. Conclusion : The TBI and non-TBI groups showed comparable results, but the TBI group showed a significantly higher 5-year EFS than the non-TBI group in ALL patients. Further prospective, randomized controlled studies involving larger number of patients are needed to assess the late-onset complications and to compare the socioeconomic quality of life.

  18. Evaluation of white cell count and differential in synovial fluid for diagnosing infections after total hip or knee arthroplasty.

    Directory of Open Access Journals (Sweden)

    Xinhua Qu

    Full Text Available BACKGROUND: The accuracy of synovial fluid (SF white cell count (WCC and polymorphonuclear (PMN cell evaluation for predicting prosthetic joint infection (PJI at the total hip arthroplasty (THA or total knee arthroplasty (TKA site is unknown. Therefore, we performed a meta-analysis to summarize the diagnostic validity of SF-WCC and SF-PMN for diagnosing PJI. METHODS: The MEDLINE, EMBASE, and OVID databases were searched for studies that had evaluated the diagnostic validity of SF-WCC and SF-PMN between January 1990 and May 2013. Meta-analysis methods were used to pool sensitivity, specificity, diagnostic odd ratios (DORs, the area under the receiver-operating characteristic curve (AUC, positive likelihood ratios (PLR, negative likelihood ratios (NLR, and post-test probability. We also conducted heterogeneity, publication bias, subgroup, and meta-regression analyses. RESULTS: Fifteen articles (15 SF-WCC and 14 SF-PMN that included a total of 2787 patients fulfilled the inclusion criteria and were considered for analysis. The pooled sensitivity and specificity for PJI detection was 0.88 (95% confidence intervals [CI], 0.81-0.93 and 0.93 (95% CI, 0.88-0.96 for SF-WCC and 0.90 (95% CI, 0.84-0.93 and 0.88 (95% CI, 0.83-0.92 for SF-PMN, respectively. The AUC was 0.96 for SF-WCC and 0.95 for SF-PMN. PLR and NLR were 13.3 and 0.13 for SF-WCC, and 7.6 and 0.12 for SF-PMN, respectively. There was no evidence of publication bias. Low-clinical-scenario (pre-test probability, 20% post-test probabilities were 3% for both negative SF-WCC and SF-PMN results. The subgroup analyses indicated that the sensitivity/specificity of THA were 0.73/0.96 for SF-WCC and 0.85/0.83 for SF-PMN, whereas those of TKA were 0.90/0.91 for SF-WCC and 0.90/0.88 for SF-PMN. We also found that collection of SF-WCC preoperatively had a higher sensitivity than that obtained intraoperatively (0.91 vs. 0.77. CONCLUSIONS: SF-WCC and SF-PMN have an adequate and clinically acceptable

  19. Genetic Algorithms and Nucleation in VIH-AIDS transition.

    Science.gov (United States)

    Barranon, Armando

    2003-03-01

    VIH to AIDS transition has been modeled via a genetic algorithm that uses boom-boom principle and where population evolution is simulated with a cellular automaton based on SIR model. VIH to AIDS transition is signed by nucleation of infected cells and low probability of infection are obtained for different mutation rates in agreement with clinical results. A power law is obtained with a critical exponent close to the critical exponent of cubic, spherical percolation, colossal magnetic resonance, Ising Model and liquid-gas phase transition in heavy ion collisions. Computations were carried out at UAM-A Supercomputing Lab and author acknowledges financial support from Division of CBI at UAM-A.

  20. [Inhibitory effect and underlying mechanism of total saponins from Paris polyphylla var. yunnanensis on the proliferation of salivary adenoid cystic carcinoma ACC-83 cells].

    Science.gov (United States)

    Qiumin, He; Biao, Xu; Weihong, Wang; Chongyun, Bao; Shaowei, Hu

    2017-06-01

    To investigate the inhibitory effect and underlying mechanism of total saponins from Paris polyphylla var. yunnanensis on the proliferation of salivary adenoid cystic carcinoma ACC-83 cells. In vitro cell culture was performed. The proliferation of ACC-83 cells treated with different concentrations (5, 10, 20, 40, 60, 80, 100 μg·mL⁻¹) of total saponins from Paris polyphylla var. yunnanensis was observed using CCK-8 assay. Meanwhile, the apoptosis of ACC-83 cells treated with different concentrations (25, 50, 100 μg·mL⁻¹) of the total saponins was observed using flow cytometry. The expression levels of macrophage migration inhibitory factor (MIF) and CD74 were measured using Western blot and reverse transcription-polymerase chain reaction. The total saponins from Paris polyphylla var. yunnanensis induced apoptosis and expressed dose-effect relationship. ACC-83 cells expressed MIF and CD74, and the total saponins suppressed MIF and CD74 expression in ACC-83 cells. The total saponins from Paris polyphylla var. yunnanensis can significantly inhibit the proliferation, suppress MIF and CD74 expression, and promote apoptosis in ACC-83 cells. This study provides a theoretical basis for the treatment of salivary adenoid cystic carcinoma using Paris polyphylla var. yunnanensis.
.

  1. Identification & Characterization of Fungal Ice Nucleation Proteins

    Science.gov (United States)

    Scheel, Jan Frederik; Kunert, Anna Theresa; Kampf, Christopher Johannes; Mauri, Sergio; Weidner, Tobias; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2016-04-01

    Freezing of water at relatively warm subfreezing temperatures is dependent on ice nucleation catalysis facilitated by ice nuclei (IN). These IN can be of various origins and although extensive research was done and progress was achieved, the nature and mechanisms leading to an effective IN are to date still poorly understood. Some of the most important processes of our geosphere like the water cycle are highly dependent on effective ice nucleation at temperatures between -2°C - -8°C, a temperature range which is almost exclusively covered by biological IN (BioIN). BioIN are usually macromolecular structures of biological polymers. Sugars as well as proteins have been reported to serve as IN and the best characterized BioIN are ice nucleation proteins (IN-P) from gram negative bacteria. Fungal strains from Fusarium spp. were described to be effective IN at subfreezing temperatures up to -2°C already 25 years ago and more and more fungal species are described to serve as efficient IN. Fungal IN are also thought to be proteins or at least contain a proteinaceous compound, but to date the fungal IN-P primary structure as well as their coding genetic elements of all IN active fungi are unknown. The aim of this study is a.) to identify the proteins and their coding genetic elements from IN active fungi (F. acuminatum, F. avenaceum, M. alpina) and b.) to characterize the mechanisms by which fungal IN serve as effective IN. We designed an interdisciplinary approach using biological, analytical and physical methods to identify fungal IN-P and describe their biological, chemical, and physical properties.

  2. Separation of nucleation and growth of voids during tensile deformation of a dual phase steel using synchrotron microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Requena, Guillermo, E-mail: guillermo.requena@tuwien.ac.at [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Maire, Eric; Leguen, Claire [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Thuillier, Sandrine [LIMATB, Université de Bretagne-Sud, rue de Saint Maudé, BP 92116, 56321 Lorient Cedex (France)

    2014-01-01

    The damage evolution in a DP980 dual phase steel is followed in situ by synchrotron microtomography during tensile deformation focusing on the effect that the triaxiality, induced by different sample geometries, exerts on damage formation and damage evolution. The growth of existing voids is separated from the voids nucleated between consecutive deformation steps using three-dimensional image analysis. The experimental results are correlated with those obtained by finite element analysis using a Gurson–Tvergaard–Needleman framework with a Chu and Needleman formulation to introduce the effect of nucleation of cavities. A relatively simple way to determine the nucleation parameters is proposed based on the volume of nucleated voids obtained from the tomographies. The evolution of the total volume fraction of cavities obtained from the calculations shows a good agreement with the experiments for the notched samples and reflects the effect of triaxiality on damage. Contrarily to experiments, the calculated accumulated volume fraction of nucleated voids does not reflect the effect of triaxiality suggesting the necessity to implement this parameter in the nucleation model.

  3. Aerosol nucleation induced by a high energy particle beam

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker; Pedersen, Jens Olaf Pepke; Uggerhøj, Ulrik I.

    The effect of ions in aerosol nucleation is a subject where much remains to be discovered. That ions can enhance nucleation has been shown by theory, observations, and experiments. However, the exact mechanism still remains to be determined. One question is if the nature of the ionization affects...... the nucleation. This is an essential question since many experiments have been performed using radioactive sources that ionize differently than the cosmic rays which are responsible for the majority of atmospheric ionization. Here we report on an experimental study of sulphuric acid aerosol nucleation under near...... atmospheric conditions using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear and significant contribution from ion induced nucleation and consider this to be an unambiguous observation of the ion-effect on aerosol nucleation using a particle beam under conditions not far...

  4. Experimental investigation of the role of ions in aerosol nucleation

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker

    The role of ions in producing aerosols in Earth’s atmosphere is an area of very active research. Atmospheric and experimental observations have shown that the nucleation of aerosol particles can occur under conditions that cannot be explained by classical nucleation theory. Several ideas have been...... put forward to solve this nucleation problem, e.g. Ion-Induced Nucleation and Ternary Nucleation. Experimental investigations exploring the role of ions in particle production are scarce, and often at conditions far removed from those relevant for the lower part of the atmosphere. Recent experimental...... were grown using photochemically produced sulphuric acid and ionization levels were controlled with a Cs-137 gamma-source. An increase in nucleation was observed when the chamber was exposed to the radioactive source. The results were analyzed using a model based on the General Dynamic Equation...

  5. A nucleator arms race: cellular control of actin assembly.

    Science.gov (United States)

    Campellone, Kenneth G; Welch, Matthew D

    2010-04-01

    For over a decade, the actin-related protein 2/3 (ARP2/3) complex, a handful of nucleation-promoting factors and formins were the only molecules known to directly nucleate actin filament formation de novo. However, the past several years have seen a surge in the discovery of mammalian proteins with roles in actin nucleation and dynamics. Newly recognized nucleation-promoting factors, such as WASP and SCAR homologue (WASH), WASP homologue associated with actin, membranes and microtubules (WHAMM), and junction-mediating regulatory protein (JMY), stimulate ARP2/3 activity at distinct cellular locations. Formin nucleators with additional biochemical and cellular activities have also been uncovered. Finally, the Spire, cordon-bleu and leiomodin nucleators have revealed new ways of overcoming the kinetic barriers to actin polymerization.

  6. Bubble nucleation in an explosive micro-bubble actuator

    International Nuclear Information System (INIS)

    Van den Broek, D M; Elwenspoek, M

    2008-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a temperature close to the critical temperature in a very short time. At these temperatures spontaneous nucleation takes place. The nucleated bubbles instantly coalesce forming a vapour film followed by rapid growth due to the pressure impulse. In this paper we take a closer look at the bubble nucleation. The moment of bubble nucleation was determined by both stroboscopic imaging and resistance thermometry. Two nucleation regimes could be distinguished. Several different heater designs were investigated under heat fluxes of hundreds of W mm −2 . A close correspondence between current density in the heater and point of nucleation was found. This results in design rules for effective heaters

  7. Binary Homogeneous Nucleation in Selected Aqueous

    Czech Academy of Sciences Publication Activity Database

    Maršík, František; Němec, Tomáš; Hrubý, Jan; Demo, Pavel; Kožíšek, Zdeněk; Petr, V.; Kolovratník, M.

    2008-01-01

    Roč. 37, č. 12 (2008), s. 1671-1708 ISSN 0095-9782 R&D Projects: GA ČR(CZ) GA101/05/2524; GA AV ČR KJB400760701; GA MŠk(CZ) 1M06031; GA AV ČR IBS2076003 Institutional research plan: CEZ:AV0Z20760514; CEZ:AV0Z10100520 Keywords : nucleation * steam * theory Subject RIV: BJ - Thermodynamics Impact factor: 1.241, year: 2008 http://www.springerlink.com/content/104381/

  8. Combined effects of DNA methyltransferase 1 and 3A polymorphisms and urinary total arsenic levels on the risk for clear cell renal cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shu-Mei [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Huang, Chao-Yuan [Department of Urology, National Taiwan University Hospital, College of Medicine National Taiwan University, Taipei, Taiwan (China); Shiue, Horng-Sheng [Department of Chinese Medicine, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taoyuan, Taiwan (China); Pu, Yeong-Shiau [Department of Urology, National Taiwan University Hospital, College of Medicine National Taiwan University, Taipei, Taiwan (China); Hsieh, Yi-Hsun; Chen, Wei-Jen [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Lin, Ying-Chin [Department of Family Medicine, Shung Ho Hospital, Taipei Medical University, Taipei, Taiwan (China); Department of Health Examination, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan (China); Division of Family Medicine, School of Medicine, Taipei Medical University, Taipei, Taiwan (China); Hsueh, Yu-Mei, E-mail: ymhsueh@tmu.edu.tw [School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China); Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China)

    2016-08-15

    Our previous study showed that high urinary total arsenic levels were associated with higher odds ratio (OR) for renal cell carcinoma (RCC). Single nucleotide polymorphisms (SNPs) of DNA methyltransferases (DNMTs) might influence DNMT enzyme activity associated with tumorigenesis. In this study, we investigated the association of five SNPs from DNMT1 (rs8101626 and rs2228611), DNMT3A (rs34048824 and rs1550117), and DNMT3B (rs1569686) with the risk of clear cell renal cell carcinoma (ccRCC). We also examined the combined effects of DNMT genotypes and urinary arsenic levels on ccRCC risk. We conducted a hospital-based case-control study, which included 293 subjects with ccRCC and 293 age- and gender-matched controls. The urinary arsenic species were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Genotypes were investigated using polymerase chain reaction and restriction fragment length polymorphism analyses. We observed that the DNMT1 rs8101626 G/G genotype was significantly associated with reduced odds ratio (OR) of ccRCC [OR = 0.38, 95% confidence interval (CI) 0.14–0.99]. Subjects with concurrent DNMT1 rs8101626 A/A + A/G and DNMT3A rs34048824 T/T + T/C genotypes had significantly higher OR for ccRCC [OR = 2.88, 95% CI 1.44–5.77]. Participants with the high-risk genotype of DNMT1 rs8101626 and DNMT3A rs34048824 with concurrently high urinary total arsenic levels had even higher OR of ccRCC in a dose-response manner. This is the first study to evaluate variant DNMT1 rs8101626 and DNMT3A rs34048824 genotypes that modify the arsenic-related ccRCC risk in a geographic area without significant arsenic exposure in Taiwan. - Highlights: • High urinary total arsenic level or polymorphism of DNMT1 increased the OR of ccRCC. • High risk genotypes of combination of DNMT1 and DNMT3A increased the OR of ccRCC. • A joint effect of urinary total arsenic level and DNMTs genotypes may affect ccRCC.

  9. Nucleation and growth of voids by radiation. Pt. 2

    International Nuclear Information System (INIS)

    Mayer, R.M.; Brown, L.M.

    1980-01-01

    The original model of Brown, Kelly and Mayer [1] for the nucleation of interstitial loops has been extended to take into account the following: (i) mobility of the vacancies, (ii) generation and migration of gas atoms during irradiation, (iii) nucleation and growth of voids, and (iv) vacancy emission from voids and clusters at high temperatures. Using chemicalrate equations, additional expressions are formulated for the nucleation and growth of vacancy loops and voids. (orig.)

  10. 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.

  11. Total Glucosides of Paeony Promote Intestinal Motility in Slow Transit Constipation Rats through Amelioration of Interstitial Cells of Cajal.

    Directory of Open Access Journals (Sweden)

    Feiye Zhu

    Full Text Available Using an atropine-diphenoxylate-induced slow transit constipation (STC model, this study explored the effects of the total glucosides of paeony (TGP in the treatment of STC and the possible mechanisms.A prospective experimental animal study.The constipation model was set up in rats with an oral gavage of atropine-diphenoxylate and then treated with the TGP. The volume and moisture content of the faeces were observed and the intestinal kinetic power was evaluated. Meanwhile, the colorimetric method and enzyme linked immunosorbent assay (ELISA were employed to determine the changes of nitric oxide (NO, nitric oxide synthase (NOS, vasoative intestinal peptide (VIP and the P substance (SP in the serum, respectively. The protein expressions of c-kit and stem cell factor (SCF were assessed by immunohistochemical analysis and western blot, respectively, and the mRNA level of c-kit was measured by a reverse transcription polymerase chain reaction (RT-PCR.The TGP attenuated STC responses in terms of an increase in the fecal volume and moisture content, an enhancement of intestinal transit rate and the reduction of NO, NOS and VIP in the serum. In addition, the c-kit, a labeling of interstitial cells of Cajal (ICC increased at both protein and mRNA levels. SCF, which serves as a ligand of c-kit also increased at protein level.The analysis of our data indicated that the TGP could obviously attenuate STC through improving the function of ICC and blocking the inhibitory neurotransmitters such as NO, NOS and VIP.

  12. Total Glucosides of Paeony Promote Intestinal Motility in Slow Transit Constipation Rats through Amelioration of Interstitial Cells of Cajal

    Science.gov (United States)

    Zhu, Feiye; Xu, Shan; Zhang, Yongsheng; Chen, Fangming; Ji, Jinjun; Xie, Guanqun

    2016-01-01

    Objectives Using an atropine-diphenoxylate-induced slow transit constipation (STC) model, this study explored the effects of the total glucosides of paeony (TGP) in the treatment of STC and the possible mechanisms. Study Design A prospective experimental animal study. Methods The constipation model was set up in rats with an oral gavage of atropine-diphenoxylate and then treated with the TGP. The volume and moisture content of the faeces were observed and the intestinal kinetic power was evaluated. Meanwhile, the colorimetric method and enzyme linked immunosorbent assay (ELISA) were employed to determine the changes of nitric oxide (NO), nitric oxide synthase (NOS), vasoative intestinal peptide (VIP) and the P substance (SP) in the serum, respectively. The protein expressions of c-kit and stem cell factor (SCF) were assessed by immunohistochemical analysis and western blot, respectively, and the mRNA level of c-kit was measured by a reverse transcription polymerase chain reaction (RT-PCR). Results The TGP attenuated STC responses in terms of an increase in the fecal volume and moisture content, an enhancement of intestinal transit rate and the reduction of NO, NOS and VIP in the serum. In addition, the c-kit, a labeling of interstitial cells of Cajal (ICC) increased at both protein and mRNA levels. SCF, which serves as a ligand of c-kit also increased at protein level. Conclusion The analysis of our data indicated that the TGP could obviously attenuate STC through improving the function of ICC and blocking the inhibitory neurotransmitters such as NO, NOS and VIP. PMID:27478893

  13. Aerosol nucleation in an ultra-low ion density environment

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean M.

    2012-01-01

    Ion-induced nucleation has been studied in a deep underground ultra-low background radiation environment where the role of ions can be distinguished from alternative neutral aerosol nucleation mechanisms. Our results demonstrate that ions have a significant effect on the production of small...... sulfuric acid–water clusters over a range of sulfuric acid concentrations although neutral nucleation mechanisms remain evident at low ionization levels. The effect of ions is found both to enhance the nucleation rate of stable clusters and the initial growth rate. The effects of possible contaminations...

  14. Nucleation in As2Se3 glass studied by DSC

    International Nuclear Information System (INIS)

    Svoboda, Roman; Málek, Jiří

    2014-01-01

    Highlights: • Nucleation behavior of As 2 Se 3 glass was studied by DSC in dependence on particle size. • Correlation between the enthalpies of fusion and crystallization were confirmed. • Apart from classical heterogeneous nucleation a second nucleation mechanism was found. • Rapid formation of crystallization centers from a damaged glassy structure occurs. • Mechanical defects seem to partially suppress the CNT nucleation process. - Abstract: Differential scanning calorimetry was used to study nucleation behavior in As 2 Se 3 glass, dependent on particle size. The nucleation process was examined for a series of different coarse powders; the nucleation rate was estimated from the proportion of the crystalline material fraction. The enthalpy of fusion was utilized in this respect, and a correlation between ΔH m and ΔH c was confirmed. Two mechanisms of nucleus formation were found: classical heterogeneous nucleation (following CNT) and so-called “activation” of mechanically-induced defects. The latter appears to represent rapid formation of crystallization centers from a damaged glassy structure, where complete saturation occurs for fine powders in the range of 195–235 °C. A high amount of mechanical defects, on the other hand, was found to partially suppress the CNT nucleation process

  15. Thermal interaction effect on nucleation site distribution in subcooled boiling

    International Nuclear Information System (INIS)

    Zou, Ling; Jones, Barclay

    2012-01-01

    An experimental work on subcooled boiling of refrigerant, R134a, to examine nucleation site distributions on both copper and stainless steel heating surfaces was performed. In order to obtain high fidelity active nucleation site density and distribution data, a high-speed digital camera was utilized to record bubble emission images from a view normal to heating surfaces. Statistical analyses on nucleation site data were done and their statistical distributions were obtained. Those experimentally observed nucleation site distributions were compared to the random spatial Poisson distribution. The comparisons showed that, rather than purely random, active nucleation site distributions on boiling surfaces are relatively more uniform. Experimental results also showed that on the copper heating surface, nucleation site distributions are slightly more uniform than on the stainless steel surface. This was concluded as the results of thermal interactions between nucleation sites with different solid thermal conductivities. A two dimensional thermal interaction model was then developed to quantitatively examine the thermal interactions between nucleation sites. The results give a reasonable explanation to the experimental observation on nucleation site distributions.

  16. Fatigue crack nucleation of type 316LN stainless steel

    International Nuclear Information System (INIS)

    Kim, Dae Whan; Kim, Woo Gon; Hong, Jun Hwa; Ryu, Woo Seog

    2000-01-01

    Low Cycle Fatigue (LCF) life decreases drastically with increasing temperature but increases with the addition of nitrogen at room and high temperatures. The effect of nitrogen on LCF life may be related to crack nucleation at high temperatures in austenitic stainless steel because the fraction of crack nucleation in LCF life is about 40%. The influence of nitrogen on the crack nucleation of LCF in type 316LN stainless steel is investigated by observations of crack population and crack depth after testing at 40% of fatigue life. Nitrogen increases the number of cycles to nucleate microcracks of 100 μm but decreases the crack population

  17. Determination of critical nucleation number for a single nucleation amyloid-β aggregation model.

    Science.gov (United States)

    Ghosh, Preetam; Vaidya, Ashwin; Kumar, Amit; Rangachari, Vijayaraghavan

    2016-03-01

    Aggregates of amyloid-β (Aβ) peptide are known to be the key pathological agents in Alzheimer disease (AD). Aβ aggregates to form large, insoluble fibrils that deposit as senile plaques in AD brains. The process of aggregation is nucleation-dependent in which the formation of a nucleus is the rate-limiting step, and controls the physiochemical fate of the aggregates formed. Therefore, understanding the properties of nucleus and pre-nucleation events will be significant in reducing the existing knowledge-gap in AD pathogenesis. In this report, we have determined the plausible range of critical nucleation number (n(*)), the number of monomers associated within the nucleus for a homogenous aggregation model with single unique nucleation event, by two independent methods: A reduced-order stability analysis and ordinary differential equation based numerical analysis, supported by experimental biophysics. The results establish that the most likely range of n(*) is between 7 and 14 and within, this range, n(*) = 12 closely supports the experimental data. These numbers are in agreement with those previously reported, and importantly, the report establishes a new modeling framework using two independent approaches towards a convergent solution in modeling complex aggregation reactions. Our model also suggests that the formation of large protofibrils is dependent on the nature of n(*), further supporting the idea that pre-nucleation events are significant in controlling the fate of larger aggregates formed. This report has re-opened an old problem with a new perspective and holds promise towards revealing the molecular events in amyloid pathologies in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Structural motifs of pre-nucleation clusters.

    Science.gov (United States)

    Zhang, Y; Türkmen, I R; Wassermann, B; Erko, A; Rühl, E

    2013-10-07

    Structural motifs of pre-nucleation clusters prepared in single, optically levitated supersaturated aqueous aerosol microparticles containing CaBr2 as a model system are reported. Cluster formation is identified by means of X-ray absorption in the Br K-edge regime. The salt concentration beyond the saturation point is varied by controlling the humidity in the ambient atmosphere surrounding the 15-30 μm microdroplets. This leads to the formation of metastable supersaturated liquid particles. Distinct spectral shifts in near-edge spectra as a function of salt concentration are observed, in which the energy position of the Br K-edge is red-shifted by up to 7.1 ± 0.4 eV if the dilute solution is compared to the solid. The K-edge positions of supersaturated solutions are found between these limits. The changes in electronic structure are rationalized in terms of the formation of pre-nucleation clusters. This assumption is verified by spectral simulations using first-principle density functional theory and molecular dynamics calculations, in which structural motifs are considered, explaining the experimental results. These consist of solvated CaBr2 moieties, rather than building blocks forming calcium bromide hexahydrates, the crystal system that is formed by drying aqueous CaBr2 solutions.

  19. Earthquake nucleation in weak subducted carbonates

    Science.gov (United States)

    Kurzawski, Robert M.; Stipp, Michael; Niemeijer, André R.; Spiers, Christopher J.; Behrmann, Jan H.

    2016-09-01

    Ocean-floor carbonate- and clay-rich sediments form major inputs to subduction zones, especially at low-latitude convergent plate margins. Therefore, knowledge of their frictional behaviour is fundamental for understanding plate-boundary earthquakes. Here we report results of mechanical tests performed on simulated fault gouges prepared from ocean-floor carbonates and clays, cored during IODP drilling offshore Costa Rica. Clay-rich gouges show internal friction coefficients (that is, the slope of linearized shear stress versus normal stress data) of μint = 0.44 - 0.56, irrespective of temperature and pore-fluid pressure (Pf). By contrast, μint for the carbonate gouge strongly depends on temperature and pore-fluid pressure, with μint decreasing dramatically from 0.84 at room temperature and Pf = 20 MPa to 0.27 at T = 140 °C and Pf = 120 MPa. This effect provides a fundamental mechanism of shear localization and earthquake generation in subduction zones, and makes carbonates likely nucleation sites for plate-boundary earthquakes. Our results imply that rupture nucleation is prompted by a combination of temperature-controlled frictional instability and temperature- and pore-pressure-dependent weakening of calcareous fault gouges.

  20. Evaluation of onset of nucleate boiling models

    Energy Technology Data Exchange (ETDEWEB)

    Huang, LiDong [Heat Transfer Research, Inc., College Station, TX (United States)], e-mail: lh@htri.net

    2009-07-01

    This article discusses available models and correlations for predicting the required heat flux or wall superheat for the Onset of Nucleate Boiling (ONB) on plain surfaces. It reviews ONB data in the open literature and discusses the continuing efforts of Heat Transfer Research, Inc. in this area. Our ONB database contains ten individual sources for ten test fluids and a wide range of operating conditions for different geometries, e.g., tube side and shell side flow boiling and falling film evaporation. The article also evaluates literature models and correlations based on the data: no single model in the open literature predicts all data well. The prediction uncertainty is especially higher in vacuum conditions. Surface roughness is another critical criterion in determining which model should be used. However, most models do not directly account for surface roughness, and most investigators do not provide surface roughness information in their published findings. Additional experimental research is needed to improve confidence in predicting the required wall superheats for nucleation boiling for engineering design purposes. (author)

  1. Evaluation of onset of nucleate boiling models

    International Nuclear Information System (INIS)

    Huang, LiDong

    2009-01-01

    This article discusses available models and correlations for predicting the required heat flux or wall superheat for the Onset of Nucleate Boiling (ONB) on plain surfaces. It reviews ONB data in the open literature and discusses the continuing efforts of Heat Transfer Research, Inc. in this area. Our ONB database contains ten individual sources for ten test fluids and a wide range of operating conditions for different geometries, e.g., tube side and shell side flow boiling and falling film evaporation. The article also evaluates literature models and correlations based on the data: no single model in the open literature predicts all data well. The prediction uncertainty is especially higher in vacuum conditions. Surface roughness is another critical criterion in determining which model should be used. However, most models do not directly account for surface roughness, and most investigators do not provide surface roughness information in their published findings. Additional experimental research is needed to improve confidence in predicting the required wall superheats for nucleation boiling for engineering design purposes. (author)

  2. Evaluation of apoptosis and micronucleation induced by reactor neutron beams with two different cadmium ratios in total and quiescent cell populations within solid tumors

    International Nuclear Information System (INIS)

    Masunaga, Shin-ichiro; Ono, Koji; Sakurai, Yoshinori; Takagaki, Masao; Kobayashi, Tooru; Kinashi, Yuko; Suzuki, Minoru

    2001-01-01

    Purpose: Response of quiescent (Q) and total tumor cells in solid tumors to reactor neutron beam irradiation with two different cadmium (Cd) ratios was examined in terms of micronucleus (MN) frequency and apoptosis frequency, using four different tumor cell lines. Methods and Materials: C57BL mice bearing EL4 tumors, C3H/He mice bearing SCC VII or FM3A tumors, and Balb/c mice bearing EMT6/KU tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously for 5 days via implanted mini-osmotic pumps to label all proliferating (P) cells. Thirty min after i.p. injection of sodium borocaptate- 10 B (BSH), or 3 h after oral administration of p-boronophenylalanine- 10 B (BPA), the tumors were irradiated with neutron beams. The tumors without 10 B-compound administration were irradiated with neutron beams or γ-rays. This neutron beam irradiation was performed using neutrons with two different Cd ratios. The tumors were then excised, minced, and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the MN frequency in cells without BrdU labeling (=Q cells) was determined using immunofluorescence staining for BrdU. Meanwhile, for apoptosis assay, 6 h after irradiation, tumor cell suspensions obtained in the same manner were fixed, and the apoptosis frequency in Q cells was also determined with immunofluorescence staining for BrdU. The MN and apoptosis frequencies in total (P+Q) tumor cells were determined from the tumors that were not pretreated with BrdU. Results: Without 10 B-compounds, the sensitivity difference between total and Q cells was reduced by neutron beam irradiation. Under our particular neutron beam irradiation condition, relative biological effectiveness (RBE) of neutrons was larger in Q cells than in total cells, and the RBE values were larger for low Cd-ratio than high Cd-ratio neutrons. With 10 B-compounds, both frequencies were increased for each cell population, especially for total cells. BPA

  3. The beneficial effect of total glucosides of paeony on psoriatic arthritis links to circulating Tregs and Th1 cell function.

    Science.gov (United States)

    Wang, Yi Na; Zhang, Yu; Wang, Yan; Zhu, Ding Xian; Xu, Li Qin; Fang, Hong; Wu, Wei

    2014-03-01

    Total glycosides of peony (TGP) is a natural immuno-modulatory drug extracted from traditional Chinese herb peony. It has been approved by State Food and Drug Administration for the treatment of rheumatoid arthritis. However, data of TGP effect on psoriatic arthritis (PsA) is still scarce. In this study, 19 patients with PsA received 12-week treatment of TGP, and clinical efficacy in joint manifestations was evaluated by DAS28 at weeks 0, 4, 8 and 12. Peripheral percentages of Tregs, Th1, Th2 and NK cells were analyzed, and serum Th1-type cytokines (IL-12, IFN-γ and TNF-α), Th2-type cytokines (IL-4, IL-5 and IL-10) as well as pro-inflammatory factors (IL-2, IL-6 and IL-8) were concomitantly examined. Six patients (32%) exhibited ≥25% decrease of DAS28 (responders). Interestingly, all responders displayed a continuous decrease in Treg and Th1 numbers during TGP treatment, concomitant with significant decreases in Th1-type cytokine levels. Serum IL-6 also showed a significant decline in responders. Non-responders lacked these sequential alterations. Thus, TGP merits further consideration as a promising therapeutic option for PsA. The result indicated that recovery of Tregs and Th1 may serve as prognostic markers to assess responsiveness to TGP treatment in PsA. Copyright © 2013 John Wiley & Sons, Ltd.

  4. Flow Cytometry Total Cell Counts: A Field Study Assessing Microbiological Water Quality and Growth in Unchlorinated Drinking Water Distribution Systems

    Science.gov (United States)

    Liu, G.; Van der Mark, E. J.; Verberk, J. Q. J. C.; Van Dijk, J. C.

    2013-01-01

    The objective of this study was to evaluate the application of flow cytometry total cell counts (TCCs) as a parameter to assess microbial growth in drinking water distribution systems and to determine the relationships between different parameters describing the biostability of treated water. A one-year sampling program was carried out in two distribution systems in The Netherlands. Results demonstrated that, in both systems, the biomass differences measured by ATP were not significant. TCC differences were also not significant in treatment plant 1, but decreased slightly in treatment plant 2. TCC values were found to be higher at temperatures above 15°C than at temperatures below 15°C. The correlation study of parameters describing biostability found no relationship among TCC, heterotrophic plate counts, and Aeromonas. Also no relationship was found between TCC and ATP. Some correlation was found between the subgroup of high nucleic acid content bacteria and ATP (R 2 = 0.63). Overall, the results demonstrated that TCC is a valuable parameter to assess the drinking water biological quality and regrowth; it can directly and sensitively quantify biomass, detect small changes, and can be used to determine the subgroup of active HNA bacteria that are related to ATP. PMID:23819117

  5. Flow Cytometry Total Cell Counts: A Field Study Assessing Microbiological Water Quality and Growth in Unchlorinated Drinking Water Distribution Systems

    Directory of Open Access Journals (Sweden)

    G. Liu

    2013-01-01

    Full Text Available The objective of this study was to evaluate the application of flow cytometry total cell counts (TCCs as a parameter to assess microbial growth in drinking water distribution systems and to determine the relationships between different parameters describing the biostability of treated water. A one-year sampling program was carried out in two distribution systems in The Netherlands. Results demonstrated that, in both systems, the biomass differences measured by ATP were not significant. TCC differences were also not significant in treatment plant 1, but decreased slightly in treatment plant 2. TCC values were found to be higher at temperatures above 15°C than at temperatures below 15°C. The correlation study of parameters describing biostability found no relationship among TCC, heterotrophic plate counts, and Aeromonas. Also no relationship was found between TCC and ATP. Some correlation was found between the subgroup of high nucleic acid content bacteria and ATP (R2=0.63. Overall, the results demonstrated that TCC is a valuable parameter to assess the drinking water biological quality and regrowth; it can directly and sensitively quantify biomass, detect small changes, and can be used to determine the subgroup of active HNA bacteria that are related to ATP.

  6. Measurement of total hemoglobin reduces red cell transfusion in hospitalized patients undergoing cardiac surgery: a retrospective database analysis.

    Science.gov (United States)

    Craver, Christopher; Belk, Kathy W; Myers, Gerard J

    2018-01-01

    Historically, perioperative hemoglobin monitoring has relied on calculated saturation, using blood gas devices that measure plasma hematocrit (Hct). Co-oximetry, which measures total hemoglobin (tHb), yields a more comprehensive assessment of hemodilution. The purpose of this study was to examine the association of tHb measurement by co-oximetry and Hct, using conductivity with red blood cell (RBC) transfusion, length of stay (LOS) and inpatient costs in patients having major cardiac surgery. A retrospective study was conducted on patients who underwent coronary artery bypass graft (CABG) and/or valve replacement (VR) procedures from January 2014 to June 2016, using MedAssets discharge data. The patient population was sub-divided by the measurement modality (tHb and Hct), using detailed billing records and Current Procedural Terminology coding. Cost was calculated using hospital-specific cost-to-charge ratios. Multivariable logistic regression was performed to identify significant drivers of RBC transfusion and resource utilization. The study population included 18,169 cardiovascular surgery patients. Hct-monitored patients accounted for 66% of the population and were more likely to have dual CABG and VR procedures (10.4% vs 8.9%, p=0.0069). After controlling for patient and hospital characteristics, as well as patient comorbidities, Hct-monitored patients had significantly higher RBC transfusion risk (OR=1.26, CI 1.15-1.38, pcosts (IRR=1.15, pcost (IRR=1.22, pcost compared to Hct monitoring.

  7. Direct calculation of ice homogeneous nucleation rate for a molecular model of water

    Science.gov (United States)

    Haji-Akbari, Amir; Debenedetti, Pablo G.

    2015-01-01

    Ice formation is ubiquitous in nature, with important consequences in a variety of environments, including biological cells, soil, aircraft, transportation infrastructure, and atmospheric clouds. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water. For molecular models, only indirect estimates have been obtained, e.g., by assuming the validity of classical nucleation theory. We use a path sampling approach to perform, to our knowledge, the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice, the most accurate among existing molecular models for studying ice polymorphs. By using a novel topological approach to distinguish different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice in the early stages of nucleation. In this competition, the cubic polymorph takes over because the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs, which give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph. This mechanism provides a molecular explanation for the earlier experimental and computational observations of the preference for cubic ice in the literature. PMID:26240318

  8. The relevance of nanoscale biological fragments for ice nucleation in clouds

    Science.gov (United States)

    O‧Sullivan, D.; Murray, B. J.; Ross, J. F.; Whale, T. F.; Price, H. C.; Atkinson, J. D.; Umo, N. S.; Webb, M. E.

    2015-01-01

    Most studies of the role of biological entities as atmospheric ice-nucleating particles have focused on relatively rare supermicron particles such as bacterial cells, fungal spores and pollen grains. However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds. Here we show that the ice-nucleating activity of a fungus from the ubiquitous genus Fusarium is related to the presence of nanometre-scale particles which are far more numerous, and therefore potentially far more important for cloud glaciation than whole intact spores or hyphae. In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample. Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles.

  9. Investigation of nucleation events vertical extent: a long term study at two different altitude sites

    Directory of Open Access Journals (Sweden)

    J. Boulon

    2011-06-01

    statistical analysis of the occurrence of nucleation over the whole lower troposphere. This work highlights the fact that nucleation can occur over a large vertical extent, at least the whole low tropospheric column, and also the fact that it occurs twice as frequently as actually detected in the planetary boundary layer. The role of sulfuric acid and ions in the nucleation process was investigated at the altitude station and no correlation was found between nucleation events and the estimated sulfuric acid concentrations. However, the contribution of ion-induced nucleation was found to be relatively high (12.49 ± 2.03 % of the total nucleation rate.

  10. New species of ice nucleating fungi in soil and air

    Science.gov (United States)

    Fröhlich-Nowoisky, Janine; Hill, Thomas C. J.; Pummer, Bernhard G.; Franc, Gray D.; Pöschl, Ulrich

    2014-05-01

    Primary biological aerosol particles (PBAP) are ubiquitous in the atmosphere (1,2). Several types of PBAP have been identified as ice nuclei (IN) that can initiate the formation of ice at relatively high temperatures (3, 4). The best-known biological IN are common plant-associated bacteria. The IN activity of these bacteria is due to a surface protein on the outer cell membrane that catalyses ice formation, for which the corresponding gene has been identified and detected by DNA analysis (3). Fungal spores or hyphae can also act as IN, but the biological structures responsible for their IN activity have not yet been elucidated. Furthermore, the abundance, diversity, sources, seasonality, properties, and effects of fungal IN in the atmosphere have neither been characterized nor quantified. Recent studies have shown that airborne fungi are highly diverse (1), and that atmospheric transport leads to efficient exchange of species among different ecosystems (5, 6). The results presented in Fröhlich-Nowoisky et al. 2012 (7) clearly demonstrate the presence of geographic boundaries in the global distribution of microbial taxa in air, and indicate that regional differences may be important for the effects of microorganisms on climate and public health. DNA analyses of aerosol samples collected during rain events showed higher diversity and frequency of occurrence for fungi belonging to the Sordariomycetes, than samples that were collected under dry conditions (8). Sordariomycetes is the class that comprises known ice nucleation active species (Fusarium spp.). By determination of freezing ability of fungal colonies isolated from air samples two species of ice nucleation active fungi that were not previously known as biological ice nucleators were found. By DNA-analysis they were identified as Isaria farinosa and Acremonium implicatum. Both fungi belong to the phylum Ascomycota, produce fluorescent spores in the range of 1-4 µm in diameter, and induced freezing at -4 and

  11. Nucleation of hydroxyapatite on Antheraea pernyi (A. pernyi) silk fibroin film.

    Science.gov (United States)

    Yang, Mingying; Shuai, Yajun; Zhou, Guanshan; Mandal, Namita; Zhu, Liangjun

    2014-01-01

    Antheraea pernyi (A. pernyi) silk fibroin, which is spun from a wild silkworm, has increasingly attracted interest in the field of tissue engineering. The aim of this study was to investigate the nucleation of hydroxyapatite (HAp) on A. pernyi fibroin film. Von Kossa staining proved that A. pernyi fibroin had Ca binding activity. The A. pernyi fibroin film was mineralized with HAp crystals by alternative soaking in calcium and phosphate solutions. Spherical crystals were nucleated on the A. pernyi fibroin film according to scanning electron microscopeimaging results. The FT-IR and X-ray diffraction spectra confirmed that these spherical crystals were HAp. The results of in vitro cell culture using MG-63 cells demonstrated that the mineralized A. pernyi fibroin film showed excellent cytocompatibility and sound improvement of the MG-63 cellviability.

  12. Total protein

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  13. Nucleation of domains under the influence of temperature in ...

    Indian Academy of Sciences (India)

    Abstract. It is found that the nucleation of domains can take place in Ba5Ti2O7Cl4 under the influence of temperature unlike in many other ferroelectrics. The nucleated domain can also be removed from the structure under the randomizing effect of tem- perature. These observations have been explained on the basis of a ...

  14. Dynamics of ice nucleation on water repellent surfaces.

    Science.gov (United States)

    Alizadeh, Azar; Yamada, Masako; Li, Ri; Shang, Wen; Otta, Shourya; Zhong, Sheng; Ge, Liehui; Dhinojwala, Ali; Conway, Ken R; Bahadur, Vaibhav; Vinciquerra, A Joseph; Stephens, Brian; Blohm, Margaret L

    2012-02-14

    Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water-surface contact area on superhydrophobic surfaces plays a dual role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air-water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications.

  15. Classical nucleation theory in the phase-field crystal model.

    Science.gov (United States)

    Jreidini, Paul; Kocher, Gabriel; Provatas, Nikolas

    2018-04-01

    A full understanding of polycrystalline materials requires studying the process of nucleation, a thermally activated phase transition that typically occurs at atomistic scales. The numerical modeling of this process is problematic for traditional numerical techniques: commonly used phase-field methods' resolution does not extend to the atomic scales at which nucleation takes places, while atomistic methods such as molecular dynamics are incapable of scaling to the mesoscale regime where late-stage growth and structure formation takes place following earlier nucleation. Consequently, it is of interest to examine nucleation in the more recently proposed phase-field crystal (PFC) model, which attempts to bridge the atomic and mesoscale regimes in microstructure simulations. In this work, we numerically calculate homogeneous liquid-to-solid nucleation rates and incubation times in the simplest version of the PFC model, for various parameter choices. We show that the model naturally exhibits qualitative agreement with the predictions of classical nucleation theory (CNT) despite a lack of some explicit atomistic features presumed in CNT. We also examine the early appearance of lattice structure in nucleating grains, finding disagreement with some basic assumptions of CNT. We then argue that a quantitatively correct nucleation theory for the PFC model would require extending CNT to a multivariable theory.

  16. Modelling the role of compositional fluctuations in nucleation kinetics

    International Nuclear Information System (INIS)

    Ženíšek, J.; Kozeschnik, E.; Svoboda, J.; Fischer, F.D.

    2015-01-01

    The classical nucleation theory of precipitate nucleation in interstitial/substitutional alloys is applied to account for the influence of spatial A–B composition fluctuations in an A–B–C matrix on the kinetics of nucleation of (A,B) 3 C precipitates. A and B are substitutional elements in the matrix and C is an interstitial component, assumed to preferentially bind to B atoms. All lattice sites are considered as potential nucleation sites. The fluctuations of chemical composition result in a local variation of the nucleation probability. The nucleation sites are eliminated from the system if they are located in a C-depleted diffusion zone belonging to an already nucleated and growing precipitate. The chemistry is that of an Fe–Cr–C system, and the specific interface energy is treated as a free parameter. Random, regular and homogeneous A–B distributions in the matrix are simulated and compared for various values of the interface energy. An increasing enhancement of the role of compositional fluctuations on nucleation kinetics with increasing interface energy and decreasing chemical driving force is observed

  17. Nucleation of voids and other irradiation-produced defect aggregates

    International Nuclear Information System (INIS)

    Wiedersich, H.; Katz, J.L.

    1976-01-01

    The nucleation of defect clusters in crystalline solids from radiation-produced defects is different from the usual nucleation processes in one important aspect: the condensing defects, interstitial atoms and vacancies, can mutually annihilate and are thus similar to matter and antimatter. The nucleation process is described as the simultaneous reaction of vacancies and interstitials (and gas atoms if present) with embryos of all sizes. The reaction rates for acquisition of point defects (and gas atoms) are calculated from their respective jump frequencies and concentrations in the supersaturated system. The reaction rates for emission of point defects are derived from the free energies of the defect clusters in the thermodynamic equilibrium system, i.e., the system without excess point defects. This procedure differs from that used in conventional nucleation theory and permits the inclusion of the ''antimatter'' defect into the set of reaction-rate equations in a straightforward manner. The method is applied to steady-state nucleation, during irradiation, of both dislocation loops and voids in the absence and in the presence of immobile and mobile gas. The predictions of the nucleation theory are shown to be in qualitative agreement with experimental observations, e.g., void densities increase with increasing displacement rates; gases such as helium enhance void nucleation; at low displacement rates and at high temperatures the presence of gas is essential to void formation. For quantitative predictions, the theory must be extended to include the termination of nucleation

  18. Thermokinetics of heterogeneous droplet nucleation on conically textured substrates.

    Science.gov (United States)

    Singha, Sanat K; Das, Prasanta K; Maiti, Biswajit

    2015-11-28

    Within the framework of the classical theory of heterogeneous nucleation, a thermokinetic model is developed for line-tension-associated droplet nucleation on conical textures considering growth or shrinkage of the formed cluster due to both interfacial and peripheral monomer exchange and by considering different geometric configurations. Along with the principle of free energy extremization, Katz kinetic approach has been employed to study the effect of substrate conicity and wettability on the thermokinetics of heterogeneous water droplet nucleation. Not only the peripheral tension is found to have a considerable effect on the free energy barrier but also the substrate hydrophobicity and hydrophilicity are observed to switch over their roles between conical crest and trough for different growth rates of the droplet. Besides, the rate of nucleation increases and further promotes nucleation for negative peripheral tension as it diminishes the free energy barrier appreciably. Moreover, nucleation inhibition can be achievable for positive peripheral tension due to the enhancement of the free energy barrier. Analyzing all possible geometric configurations, the hydrophilic narrower conical cavity is found to be the most preferred nucleation site. These findings suggest a physical insight into the context of surface engineering for the promotion or the suppression of nucleation on real or engineered substrates.

  19. Nucleation path of helium bubbles in metals during irradiation

    International Nuclear Information System (INIS)

    Morishita, Kazunori

    2008-01-01

    Thermodynamical formalization is made for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available or evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion divertor materials where helium particles with low energy are directly implanted. Calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barrier without helium. With the proposed thermodynamical formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte-Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He , N V ) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the number of helium atoms and vacancies in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion. (author)

  20. Protein Polymerization into Fibrils from the Viewpoint of Nucleation Theory.

    Science.gov (United States)

    Kashchiev, Dimo

    2015-11-17

    The assembly of various proteins into fibrillar aggregates is an important phenomenon with wide implications ranging from human disease to nanoscience. Using general kinetic results of nucleation theory, we analyze the polymerization of protein into linear or helical fibrils in the framework of the Oosawa-Kasai (OK) model. We show that while within the original OK model of linear polymerization the process does not involve nucleation, within a modified OK model it is nucleation-mediated. Expressions are derived for the size of the fibril nucleus, the work for fibril formation, the nucleation barrier, the equilibrium and stationary fibril size distributions, and the stationary fibril nucleation rate. Under otherwise equal conditions, this rate decreases considerably when the short (subnucleus) fibrils lose monomers much more frequently than the long (supernucleus) fibrils, a feature that should be born in mind when designing a strategy for stymying or stimulating fibril nucleation. The obtained dependence of the nucleation rate on the concentration of monomeric protein is convenient for experimental verification and for use in rate equations accounting for nucleation-mediated fibril formation. The analysis and the results obtained for linear fibrils are fully applicable to helical fibrils whose formation is describable by a simplified OK model. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Determination of the void nucleation rate from void size distributions

    International Nuclear Information System (INIS)

    Brailsford, A.D.

    1977-01-01

    A method of estimating the void nucleation rate from one void size distribution and from observation of the maximum void radius at prior times is proposed. Implicit in the method are the assumptions that both variations in the critical radius with dose and vacancy thermal emission processes during post-nucleation quasi-steady-state growth may be neglected. (Auth.)

  2. Bubble nucleation in an explosive micro-bubble actuator

    NARCIS (Netherlands)

    van den Broek, D.M.; Elwenspoek, Michael Curt

    2008-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a temperature close to the critical temperature in a very short time. At these temperatures spontaneous nucleation takes place. The nucleated bubbles instantly coalesce forming a vapour film followed by rapid growth due to the pressure

  3. Nucleation of superconductivity under rapid cycling of an electric field

    International Nuclear Information System (INIS)

    Bandyopadhyay, Malay

    2008-01-01

    The effect of an externally applied high-frequency oscillating electric field on the critical nucleation field of superconductivity in the bulk as well as at the surface of a superconductor is investigated in detail in this work. Starting from the linearized time-dependent Ginzburg-Landau (TDLG) theory, and using the variational principle, I have shown the analogy between a quantum harmonic oscillator with that of the nucleation of superconductivity in the bulk and a quantum double oscillator with that of the nucleation at the surface of a finite sample. The effective Hamiltonian approach of Cook et al (1985 Phys. Rev. A 31 564) is employed to incorporate the effect of an externally applied highly oscillating electric field. The critical nucleation field ratio is also calculated from the ground state energy method. The results obtained from these two approximate theories agree very well with the exact results for the case of an undriven system, which establishes the validity of these two approximate theories. It is observed that the highly oscillating electric field actually increases the bulk critical nucleation field (H c 2 ) as well as the surface critical nucleation field (H c 3 ) of superconductivity as compared to the case of absent electric field (ε 0 = 0). But the externally applied rapidly oscillating electric field accentuates the surface critical nucleation field more than the bulk critical nucleation field, i.e. the increase of H c 3 is 1.6592 times larger than that of H c 2

  4. Focus: Nucleation kinetics of shear bands in metallic glass.

    Science.gov (United States)

    Wang, J Q; Perepezko, J H

    2016-12-07

    The development of shear bands is recognized as the primary mechanism in controlling the plastic deformability of metallic glasses. However, the kinetics of the nucleation of shear bands has received limited attention. The nucleation of shear bands in metallic glasses (MG) can be investigated using a nanoindentation method to monitor the development of the first pop-in event that is a signature of shear band nucleation. The analysis of a statistically significant number of first pop-in events demonstrates the stochastic behavior that is characteristic of nucleation and reveals a multimodal behavior associated with local spatial heterogeneities. The shear band nucleation rate of the two nucleation modes and the associated activation energy, activation volume, and site density were determined by loading rate experiments. The nucleation activation energy is very close to the value that is characteristic of the β relaxation in metallic glass. The identification of the rate controlling kinetics for shear band nucleation offers guidance for promoting plastic flow in metallic glass.

  5. Water nucleation : wave tube experiments and theoretical considerations

    NARCIS (Netherlands)

    Holten, V.

    2009-01-01

    This work is an experimental and theoretical study of the condensation of water. Condensation consists of nucleation – the formation of droplets – and the subsequent growth of those droplets. In our expansion tube setup, these processes are separated in time with the nucleation pulse principle, in

  6. Heterogeneous primary nucleation of ice in water and aqueous solutions

    NARCIS (Netherlands)

    Thijssen, H.A.C.; Vorstman, M.A.G.; Roels, J.A.

    1968-01-01

    The effect of the volume of the liquid sample, the degree of turbulence in the liquid, and the rate of cooling upon the probability of nucleation has been studied for water and aqueous solutions. Nucleation rates were measured for droplets nearly instantaneously cooled to a predetermined

  7. Determining the nucleation rate from the dimer growth probability

    NARCIS (Netherlands)

    Ter Horst, J.H.; Kashchiev, D.

    2005-01-01

    A new method is proposed for the determination of the stationary one-component nucleation rate J with the help of data for the growth probability P2 of a dimer which is the smallest cluster of the nucleating phase. The method is based on an exact formula relating J and P2, and is readily applicable

  8. Classical nucleation theory in the phase-field crystal model

    Science.gov (United States)

    Jreidini, Paul; Kocher, Gabriel; Provatas, Nikolas

    2018-04-01

    A full understanding of polycrystalline materials requires studying the process of nucleation, a thermally activated phase transition that typically occurs at atomistic scales. The numerical modeling of this process is problematic for traditional numerical techniques: commonly used phase-field methods' resolution does not extend to the atomic scales at which nucleation takes places, while atomistic methods such as molecular dynamics are incapable of scaling to the mesoscale regime where late-stage growth and structure formation takes place following earlier nucleation. Consequently, it is of interest to examine nucleation in the more recently proposed phase-field crystal (PFC) model, which attempts to bridge the atomic and mesoscale regimes in microstructure simulations. In this work, we numerically calculate homogeneous liquid-to-solid nucleation rates and incubation times in the simplest version of the PFC model, for various parameter choices. We show that the model naturally exhibits qualitative agreement with the predictions of classical nucleation theory (CNT) despite a lack of some explicit atomistic features presumed in CNT. We also examine the early appearance of lattice structure in nucleating grains, finding disagreement with some basic assumptions of CNT. We then argue that a quantitatively correct nucleation theory for the PFC model would require extending CNT to a multivariable theory.

  9. Total Skin Electron Therapy for Cutaneous T-Cell Lymphoma Using a Modern Dual-Field Rotational Technique

    Energy Technology Data Exchange (ETDEWEB)

    Heumann, Thatcher R. [Emory University School of Medicine, Emory University, Atlanta, Georgia (United States); Esiashvili, Natia [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute (WCI), Emory University, Atlanta, Georgia (United States); Parker, Sareeta [Department of Dermatology, Emory University, Atlanta, Georgia (United States); Switchenko, Jeffrey M. [Biostatistics Shared Core Resource at WCI, Emory University, Atlanta, Georgia (United States); Dhabbaan, Anees [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute (WCI), Emory University, Atlanta, Georgia (United States); Goodman, Michael [Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia (United States); Lechowicz, Mary Jo; Flowers, Christopher R. [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Department of Hematology and Oncology, Emory University, Atlanta, Georgia (United States); Khan, Mohammad K., E-mail: drkhurram2000@gmail.com [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute (WCI), Emory University, Atlanta, Georgia (United States)

    2015-05-01

    Purpose: To report our experience with rotational total skin electron irradiation (RTSEI) in cutaneous T-cell lymphoma (CTCL), and to examine response by disease stage and race. Methods and Materials: We reviewed our outcomes for 68 CTCL patients who received RTSEI (≥30 Gy) from 2000 to 2013. Primary outcomes were complete clinical response (CCR), recurrence-free survival (RFS), and overall survival (OS). Using log–rank tests and Cox proportional hazards, OS and RFS were compared across tumor stages at time of RTSEI with further racial subgroup analysis. Results: Median age at diagnosis and at time of radiation was 52 and 56 years, respectively. Median follow-up was 5.1 years, 49% were African American, and 49% were female. At time of treatment, 18, 37, and 13 patients were T stage 2, 3, and 4, respectively. At 6 weeks after RTSEI, overall CCR was 82% (88%, 83%, and 69% for T2, T3, and T4, respectively). Median RFS was 11 months for all patients and 14, 10, and 12 months for stage T2, T3, and T4, respectively. Tumor stage was not associated with RFS or CCR. Maintenance therapy after RTSEI was associated with improved RFS in both crude and multivariable analysis, controlling for T stage. Median OS was 76 months (91 and 59 months for T3 and T4, respectively). With the exception of improved OS in African Americans compared with whites at stage T2, race was not associated with CCR, RFS, or OS. Conclusions: These results represent the largest RTSEI clinical outcomes study in the modern era using a dual-field rotational technique. Our observed response rates match or improve upon the standard set by previous outcome studies using conventional TSEI techniques, despite a large percentage of advanced CTCL lesions in our cohort. We found that clinical response after RTSEI did not seem to be affected by T stage or race.

  10. Prognostic significance of total lesion glycolysis in patients with advanced non-small cell lung cancer receiving chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Zaizen, Yoshiaki [Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume (Japan); Azuma, Koichi, E-mail: azuma@med.kurume-u.ac.jp [Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume (Japan); Kurata, Seiji [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Sadashima, Eiji; Hattori, Satoshi [Biostatistics Center, Kurume University, Kurume (Japan); Sasada, Tetsuro [Department of Immunology and Immunotherapy, Kurume University School of Medicine, Kurume (Japan); Imamura, Yohei [Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume (Japan); Kaida, Hayato [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Kawahara, Akihiko [Department of Pathology, Kurume University School of Medicine, Kurume (Japan); Kinoshita, Takashi [Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume (Japan); Ishibashi, Masatoshi [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Hoshino, Tomoaki [Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume (Japan)

    2012-12-15

    Background: [{sup 18}F]fluorodeoxyglucose positron emission tomography (FDG-PET) imaging has been employed as a non-invasive diagnostic tool for malignant tumors. Total lesion glycolysis (TLG) on FDG-PET is calculated by multiplying the mean standardized uptake value (SUVmean) by the tumor volume. Unlike the maximum standardized uptake value (SUVmax), which represents the point of greatest metabolic activity within tumors, TLG has been suggested to reflect global metabolic activity in whole tumors. Methods: We retrospectively examined whether or not FDG-PET measurements, including SUVmean, SUVmax, and TLG, could predict progression-free survival (PFS) or overall survival (OS) in patients with non-small cell lung cancer (NSCLC) receiving chemotherapy. Results: This study involved 81 consecutive patients with NSCLC who received chemotherapy. All of the patients underwent FDG-PET examination before treatment. SUVmean, SUVmax, and TLG on FDG-PET were significantly associated with gender, smoking status, and tumor histology. With adjustment for several other variables, Cox regression analysis showed that TLG was significantly prognostic for both PFS [hazard ratio = 2.34; 95% confidence interval, 1.18–4.64; P = 0.015] and OS (hazard ratio = 2.80; 95% confidence interval, 1.12–6.96; P = 0.003), whereas SUVmean and SUVmax had no significant association with PFS (P = 0.693 and P = 0.322, respectively) or OS (P = 0.587 and P = 0.214, respectively). Conclusions: Our findings suggest that TLG may be more useful than SUVmean and SUVmax for predicting PFS and OS in NSCLC patients receiving chemotherapy. The TLG measurement on FDG-PET imaging could be routinely recommended to advanced NSCLC patients.

  11. Experimental validation of kinetic inhibitor strength on natural gas hydrate nucleation

    DEFF Research Database (Denmark)

    Daraboina, Nagu; Pachitsas, Stylianos; von Solms, Nicolas

    2015-01-01

    The kinetics of natural gas hydrate formation in the presence of dissolved salts (NaCl) and crude oil ( a middle east crude with density 851.5 kg/m3 were investigated by using a standard rocking cell (RC-5) apparatus. The hydrate nucleation temperature was reduced in the presence of NaCl and oil...... management in oil and gas facilities. (C) 2014 Elsevier Ltd. All rights reserved....

  12. Preparation and nucleation of spherical metallic droplet

    Directory of Open Access Journals (Sweden)

    Bing-ge Zhao

    2015-03-01

    Full Text Available The preparation and solidification of metallic droplets attract more and more attention for their significance in both engineering and scientific fields. In this paper, the preparation and characterization of Sn-based alloy droplets using different methods such as atomization and consumable electrode direct current arc (CDCA technique are reviewed. The morphology and structure of these droplets were determined by optical microscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The solidification behavior of single droplet was systematically studied by means of scanning calorimetry (DSC, and the nucleation kinetics was also calculated. In particular, the development of fast scanning calorimetry (FSC made it possible to investigate the evolution of undercooling under ultrafast but controllable heating and cooling conditions. The combination of CDCA technique and FSC measurements opens up a new door for quantitative studies on droplet solidification, which is accessible to demonstrate some theories by experiments.

  13. Magnetic droplet soliton nucleation in oblique fields

    Science.gov (United States)

    Mohseni, Morteza; Hamdi, M.; Yazdi, H. F.; Banuazizi, S. A. H.; Chung, S.; Sani, S. R.; Åkerman, Johan; Mohseni, Majid

    2018-05-01

    We study the auto-oscillating magnetodynamics in orthogonal spin-torque nano-oscillators (STNOs) as a function of the out-of-plane (OOP) magnetic-field angle. In perpendicular fields and at OOP field angles down to approximately 50°, we observe the nucleation of a droplet. However, for field angles below 50°, experiments indicate that the droplet gives way to propagating spin waves, in agreement with our micromagnetic simulations. Theoretical calculations show that the physical mechanism behind these observations is the sign changing of spin-wave nonlinearity (SWN) by angle. In addition, we show that the presence of a strong perpendicular magnetic anisotropy free layer in the system reverses the angular dependence of the SWN and dynamics in STNOs with respect to the known behavior determined for the in-plane magnetic anisotropy free layer. Our results are of fundamental interest in understanding the rich dynamics of nanoscale solitons and spin-wave dynamics in STNOs.

  14. An improved nucleate boiling design equation

    International Nuclear Information System (INIS)

    Basu, D.K.; Pinder, K.L.

    1976-01-01

    The effect of varying ΔT, the primary variable, on the value of heat transfer coefficient (h) in nucleate boiling is discussed. The three-parameter quadratic equation, h=P 1 + P 2 (ΔT) + P 3 (ΔT) 2 (where the constants, P 1 ,P 2 ,P 3 are functions of pressure, liquid properties and surface properties of the heater) is suggested. Ten sets of data at atmospheric pressure from six different workers and two more sets for pressure variation have been tested. The above quadratic equation fits the experimental data better than the existing two-parameter power relation, h=C(ΔT)sup(n) (where C is constant). The values of the three coeffcients in the quadratic equations are dependent on pressure, liquid properties and surface properties. A generalized empirical equation has been derived, which fits the selected pressure data well. (author)

  15. Progress Towards Identifying and Quantifying the Organic Ice Nucleating Particles in Soils and Aerosols

    Science.gov (United States)

    Hill, T. C. J.; DeMott, P. J.; Fröhlich-Nowoisky, J.; Tobo, Y.; Suski, K. J.; Levin, E. J.; Kreidenweis, S. M.; Franc, G. D.

    2014-12-01

    Soil and plant surfaces emit ice nucleating particles (INP) to the atmosphere, especially when disturbed by wind, harvesting, rain or fire. Organic (biogenic) INP are abundant in most soils and dominate the population that nucleate >-15°C. For example, the sandy topsoil of sagebrush shrubland, a widespread ecotype prone to wind erosion after fire, contains ~106 organic INP g-1 at -6°C. The relevance of organic INP may also extend to colder temperatures than previously thought: Particles of soil organic matter (SOM) have been shown to be more important than mineral particles for the ice nucleating ability of agricultural soil dusts to -34°C. While the abundance of ice nucleation active (INA) bacteria on plants has been established, the identity of the organic INP in and emitted by soils remains a 40-year-old mystery. The need to understand their production and release is highlighted by recent findings that INA bacteria (measured with qPCR) account for few, if any, of the warm-temperature organic INP that predominate in boundary layer aerosols and snow; organic INP lofted with soil dusts seem a likely source. The complexity of SOM hinders its investigation. It contains decomposing plant materials, a diverse microbial and microfaunal community, humus, and inert organic matter. All are biochemically complex and all may contain ice nucleating constituents, either by design or by chance. Indeed the smoothness of the INP temperature spectra of soils is indicative of numerous, overlapping distributions of INP. We report recent progress in identifying and quantifying the organic INP in soils and boundary layer aerosols representative of West Central U.S. ecosystems, and how their characteristics may affect their dispersal. Chemical, enzymatic and DNA-based tests were used to assess contributions of INP from plant tissues, INA bacteria, INA fungi, organic crystals, monolayers of aliphatic alcohols, carbohydrates, and humic substances, while heat- and peroxide-based tests

  16. Impact of bacterial ice nucleating particles on weather predicted by a numerical weather prediction model

    Science.gov (United States)

    Sahyoun, Maher; Korsholm, Ulrik S.; Sørensen, Jens H.; Šantl-Temkiv, Tina; Finster, Kai; Gosewinkel, Ulrich; Nielsen, Niels W.

    2017-12-01

    Bacterial ice-nucleating particles (INP) have the ability to facilitate ice nucleation from super-cooled cloud droplets at temperatures just below the melting point. Bacterial INP have been detected in cloud water, precipitation, and dry air, hence they may have an impact on weather and climate. In modeling studies, the potential impact of bacteria on ice nucleation and precipitation formation on global scale is still uncertain due to their small concentration compared to other types of INP, i.e. dust. Those earlier studies did not account for the yet undetected high concentration of nanoscale fragments of bacterial INP, which may be found free or attached to soil dust in the atmosphere. In this study, we investigate the sensitivity of modeled cloud ice, precipitation and global solar radiation in different weather scenarios to changes in the fraction of cloud droplets containing bacterial INP, regardless of their size. For this purpose, a module that calculates the probability of ice nucleation as a function of ice nucleation rate and bacterial INP fraction was developed and implemented in a numerical weather prediction model. The threshold value for the fraction of cloud droplets containing bacterial INP needed to produce a 1% increase in cloud ice was determined at 10-5 to 10-4. We also found that increasing this fraction causes a perturbation in the forecast, leading to significant differences in cloud ice and smaller differences in convective and total precipitation and in net solar radiation reaching the surface. These effects were most pronounced in local convective events. Our results show that bacterial INP can be considered as a trigger factor for precipitation, but not an enhancement factor.

  17. Using the Optical Fractionator to Estimate Total Cell Numbers in the Normal and Abnormal Developing Human Forebrain

    DEFF Research Database (Denmark)

    Larsen, Karen B

    2017-01-01

    abnormal development. Furthermore, many studies of brain cell numbers have employed biased counting methods, whereas innovations in stereology during the past 20-30 years enable reliable and efficient estimates of cell numbers. However, estimates of cell volumes and densities in fetal brain samples...

  18. Copper Oxidation through Nucleation Sites of Chemical Vapor Deposited Graphene

    DEFF Research Database (Denmark)

    Luo, Birong; Whelan, Patrick Rebsdorf; Shivayogimath, Abhay

    2016-01-01

    We investigate the nucleation defect-triggered oxidation of Cu covered by CVD graphene during postannealing in air. The results reveal that different growth conditions may induce imperfect nucleation of graphene, and cause creation of defects near the nucleation point such as pin holes...... and amorphous carbon. These defects would serve as a pathway for the diffusion of 02 during thermal annealing, allowing oxidation of Cu to progress gradually from the nucleation center toward the growth edge. The oxidation process follows the graphene morphology closely; the shape of the oxidized area of Cu has...... a striking resemblance to that of the graphene flakes. Our work demonstrates that inferior graphene nucleation in CVD processes can compromise the oxidation resistance of a graphene-coated Cu substrate, and indirectly reveal the structure and integrity of graphene, which is of fundamental importance...

  19. Homogeneous nucleation in 4He: A corresponding-states analysis

    International Nuclear Information System (INIS)

    Sinha, D.N.; Semura, J.S.; Brodie, L.C.

    1982-01-01

    We report homogeneous-nucleation-temperature measurements in liquid 4 He over a bath-temperature range 2.31 4 He, in a region far from the critical point. A simple empirical form is presented for estimating the homogeneous nucleation temperatures for any liquid with a spherically symmetric interatomic potential. The 4 He data are compared with nucleation data for Ar, Kr, Xe, and H; theoretical predictions for 3 He are given in terms of reduced quantities. It is shown that the nucleation data for both quantum and classical liquids obey a quantum law of corresponding states (QCS). On the basis of this QCS analysis, predictions of homogeneous nucleation temperatures are made for hydrogen isotopes such as HD, DT, HT, and T 2

  20. Aerosol nucleation induced by a high energy particle beam

    DEFF Research Database (Denmark)

    Enghoff, Martin Andreas Bødker; Pedersen, Jens Olaf Pepke; Uggerhøj, Ulrik I.

    2011-01-01

    We have studied sulfuric acid aerosol nucleation in an atmospheric pressure reaction chamber using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear contribution from ion-induced nucleation and consider this to be the first unambiguous observation of the ion......-effect on aerosol nucleation using a particle beam under conditions that resemble the Earth's atmosphere. By comparison with ionization using a gamma source we further show that the nature of the ionizing particles is not important for the ion-induced component of the nucleation. This implies that inexpensive...... ionization sources - as opposed to expensive accelerator beams - can be used for investigations of ion-induced nucleation....

  1. Transplantation tolerance in primates following total lymphoid irradiation and allogeneic bone marrow injection. II. Renal allographs

    International Nuclear Information System (INIS)

    Myburgh, J.A.; Smit, J.A.; Hill, R.R.H.; Browde, S.

    1980-01-01

    A modified regimen of fractionated total lymphoid irradiation and allogeneic bone marrow (BM) injection in chacma baboons produced transplantation tolerance for allografted kidneys from the BM donors, and substantial chimerism without evidence of graft-versus-host disease. Increasing the dose of nucleated BM cells injected 4-fold over that used in liver transplantation resulted consistently in normal graft function in the early weeks after transplantation. Bone marrow injection and challenge with renal allografts could be delayed for at least 3 weeks after completion of irradiation. If it can be shown that this period can be extended even further, the protocols will be relevant to the circumstances of clinical cadaveric renal transplantation

  2. Visual observation of gas hydrates nucleation and growth at a water - organic liquid interface

    Science.gov (United States)

    Stoporev, Andrey S.; Semenov, Anton P.; Medvedev, Vladimir I.; Sizikov, Artem A.; Gushchin, Pavel A.; Vinokurov, Vladimir A.; Manakov, Andrey Yu.

    2018-03-01

    Visual observation of nucleation sites of methane and methane-ethane-propane hydrates and their further growth in water - organic liquid - gas systems with/without surfactants was carried out. Sapphire Rocking Cell RCS6 with transparent sapphire cells was used. The experiments were conducted at the supercooling ΔTsub = 20.2 °C. Decane, toluene and crude oils were used as organics. Gas hydrate nucleation occurred on water - metal - gas and water - sapphire - organic liquid three-phase contact lines. At the initial stage of growth hydrate crystals rapidly covered the water - gas or water - organics interfaces (depending on the nucleation site). Further hydrate phase accrete on cell walls (sapphire surface) and into the organics volume. At this stage, growth was accompanied by water «drawing out» from under initial hydrate film formed at water - organic interface. Apparently, it takes place due to water capillary inflow in the reaction zone. It was shown that the hydrate crystal morphology depends on the organic phase composition. In the case of water-in-decane emulsion relay hydrate crystallization was observed in the whole sample, originating most likely due to the hydrate crystal intergrowth through decane. Contacts of such crystals with adjacent water droplets result in rapid hydrate crystallization on this droplet.

  3. Free energy landscape and molecular pathways of gas hydrate nucleation

    International Nuclear Information System (INIS)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu

    2016-01-01

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p B histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p B histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  4. Free energy landscape and molecular pathways of gas hydrate nucleation.

    Science.gov (United States)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu

    2016-12-07

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p B histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p B histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  5. Do protein crystals nucleate within dense liquid clusters?

    International Nuclear Information System (INIS)

    Maes, Dominique; Vorontsova, Maria A.; Potenza, Marco A. C.; Sanvito, Tiziano; Sleutel, Mike; Giglio, Marzio; Vekilov, Peter G.

    2015-01-01

    The evolution of protein-rich clusters and nucleating crystals were characterized by dynamic light scattering (DLS), confocal depolarized dynamic light scattering (cDDLS) and depolarized oblique illumination dark-field microscopy. Newly nucleated crystals within protein-rich clusters were detected directly. These observations indicate that the protein-rich clusters are locations for crystal nucleation. Protein-dense liquid clusters are regions of high protein concentration that have been observed in solutions of several proteins. The typical cluster size varies from several tens to several hundreds of nanometres and their volume fraction remains below 10 −3 of the solution. According to the two-step mechanism of nucleation, the protein-rich clusters serve as locations for and precursors to the nucleation of protein crystals. While the two-step mechanism explained several unusual features of protein crystal nucleation kinetics, a direct observation of its validity for protein crystals has been lacking. Here, two independent observations of crystal nucleation with the proteins lysozyme and glucose isomerase are discussed. Firstly, the evolutions of the protein-rich clusters and nucleating crystals were characterized simultaneously by dynamic light scattering (DLS) and confocal depolarized dynamic light scattering (cDDLS), respectively. It is demonstrated that protein crystals appear following a significant delay after cluster formation. The cDDLS correlation functions follow a Gaussian decay, indicative of nondiffusive motion. A possible explanation is that the crystals are contained inside large clusters and are driven by the elasticity of the cluster surface. Secondly, depolarized oblique illumination dark-field microscopy reveals the evolution from liquid clusters without crystals to newly nucleated crystals contained in the clusters to grown crystals freely diffusing in the solution. Collectively, the observations indicate that the protein-rich clusters in

  6. Free energy landscape and molecular pathways of gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Yuanfei; Porras, Anna; Li, Tianshu, E-mail: tsli@gwu.edu [Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052 (United States)

    2016-12-07

    Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), p{sub B} histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the p{sub B} histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.

  7. Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

    Directory of Open Access Journals (Sweden)

    C. D. O'Dowd

    2007-01-01

    Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

  8. Homogeneous ice nucleation from aqueous inorganic/organic particles representative of biomass burning: water activity, freezing temperatures, nucleation rates.

    Science.gov (United States)

    Knopf, Daniel A; Rigg, Yannick J

    2011-02-10

    Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ∼60 μm for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ∼2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice

  9. Elucidating Key Motifs Required for Arp2/3-Dependent and Independent Actin Nucleation by Las17/WASP

    Science.gov (United States)

    Urbanek, Agnieszka N.; Smaczynska-de Rooij, Iwona I.

    2016-01-01

    Actin nucleation is the key rate limiting step in the process of actin polymerization, and tight regulation of this process is critical to ensure actin filaments form only at specific times and at defined regions of the cell. Arp2/3 is a well-characterised protein complex that can promote nucleation of new filaments, though its activity requires additional nucleation promotion factors (NPFs). The best recognized of these factors are the WASP family of proteins that contain binding motifs for both monomeric actin and for Arp2/3. Previously we demonstrated that the yeast WASP homologue, Las17, in addition to activating Arp2/3 can also nucleate actin filaments de novo, independently of Arp2/3. This activity is dependent on its polyproline rich region. Through biochemical and in vivo analysis we have now identified key motifs within the polyproline region that are required for nucleation and elongation of actin filaments, and have addressed the role of the WH2 domain in the context of actin nucleation without Arp2/3. We have also demonstrated that full length Las17 is able to bind liposomes giving rise to the possibility of direct linkage of nascent actin filaments to specific membrane sites to which Las17 has been recruited. Overall, we propose that Las17 functions as the key initiator of de novo actin filament formation at endocytic sites by nucleating, elongating and tethering nascent filaments which then serve as a platform for Arp2/3 recruitment and function. PMID:27637067

  10. Functional clonal deletion versus suppressor cell-induced transplantation tolerance in chimeras prepared with a short course of total-lymphoid irradiation

    International Nuclear Information System (INIS)

    Slavin, S.; Morecki, S.; Weigensberg, M.; Bar, S.; Weiss, L.

    1986-01-01

    Allogeneic bone marrow (BM) chimeras induced by infusion of BM cells into recipients conditioned with total lymphoid irradiation (TLI) were shown to develop humoral and cell-mediated tolerance to host and donor-type alloantigens by a number of in vitro and in vivo assays. Spleen cells of tolerant chimeras exhibited suppressive activity of mixed lymphocyte reaction (MLR). MLR suppression was not abrogated by depletion of Lyt-2 cells, and neither could Lyt-2-positive cells sorted from the spleens of tolerant chimeras suppress MLR or attenuate graft-versus-host reactivity in vivo. Likewise, specifically unresponsive spleen cells obtained from chimeras could not be induced to respond in MLR against tolerizing host-type cells following depletion of Lyt-2 or passage through a nylon-wool column. Tolerance of chimera spleen cells to host alloantigens, best documented by permanent survival of donor-type skin allografts, could be adoptively transferred into syngeneic recipients treated by heavy irradiation but not into untreated or mildly irradiated recipients. Adoptive transfer of tolerance seemed to be associated with experimental conditions favoring engraftment of tolerant cells rather than suppression of host reactivity. We speculate that although host and/or donor-derived suppressor cells may be operating in reducing the pool of specific alloreactive clones by blocking cell proliferation in response to allogeneic challenge, the final outcome in tolerant chimeras is actual or functional deletion of alloreactive clones

  11. Busulfan and total body irradiation as antihematopoietic stem cell agents in the preparation of patients with congenital bone marrow disorders for allogenic bone marrow transplantation

    International Nuclear Information System (INIS)

    Parkman, R.; Rappeport, J.M.; Hellman, S.; Lipton, J.; Smith, B.; Geha, R.; Nathan, D.G.

    1984-01-01

    The capacity of busulfan and total body irradiation to ablate hematopoietic stem cells as preparation for the allogeneic bone marrow transplantation of patients with congenital bone marrow disorders was studied. Fourteen patients received 18 transplants; busulfan was used in the preparatory regimen of eight transplants and total body irradiation in the regimens of six transplants. Sustained hematopoietic ablation was achieved in six of eight patients prepared with busulfan and in all six patients prepared with total body irradiation. Three patients prepared with total body irradiation died with idiopathic interstitial pneumonitis, whereas no patients receiving busulfan developed interstitial pneumonitis. The optimal antihematopoietic stem cell agent to be used for the preparation of patients with congenital bone marrow disorder for bone marrow transplantation is not certain

  12. Ganoderma lucidum total triterpenes induce apoptosis in MCF-7 cells and attenuate DMBA induced mammary and skin carcinomas in experimental animals.

    Science.gov (United States)

    Smina, T P; Nitha, B; Devasagayam, T P A; Janardhanan, K K

    2017-01-01

    Ganoderma lucidum total triterpenes were evaluated for its apoptosis-inducing and anti-cancer activities. Cytotoxicity and pro-apoptotic effect of total triterpenes were evaluated in human breast adenocarcinoma (MCF-7) cell line using MTT assay and DNA fragmentation analysis. Total triterpenes induced apoptosis in MCF-7 cells by down-regulating the levels of cyclin D1, Bcl-2, Bcl-xL and also by up-regulating the levels of Bax and caspase-9. Anti-carcinogenicity of total triterpenes was analysed using dimethyl benz [a] anthracene (DMBA) induced skin papilloma and mammary adenocarcinoma in Swiss albino mice and Wistar rats respectively. Topical application of 5mg, 10mg and 20mg total triterpenes reduced the incidence of skin papilloma by 62.5, 37.5 and 12.5% respectively. Incidence of the mammary tumour was also reduced significantly by 33.33, 66.67 and 16.67% in 10, 50 and 100mg/kg b.wt. total triterpenes treated animals respectively. Total triterpenes were also found to reduce the average number of tumours per animal and extended the tumour latency period in both the models. The results indicate the potential cytotoxicity and anti-cancerous activity of total triterpenes, there by opens up a path to the development of a safe and successive chemo preventive agent of natural origin. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Cluster-assisted nucleation of silicon phase in hypoeutectic Al–Si alloy with further inoculation

    International Nuclear Information System (INIS)

    Zhang, Yong; Zheng, Hongliang; Liu, Yue; Shi, Lei; Xu, Rongfu; Tian, Xuelei

    2014-01-01

    The paper discusses the responses of eutectic silicon and eutectic cells in Al–10Si alloy upon inoculation with an Al–10Si–2Fe master alloy. The further inoculation hardly destroys the modification effect of Sr but significantly refines the eutectic cells in Sr-modified samples, while in unmodified samples, it stimulates the occurrences of polyhedral silicon particles and divorced eutectic. Thermal analysis, scanning electron microscopy, (high-resolution) transmission electron microscopy and scanning and transmission electron microscopy have been used to elucidate the underlying mechanism. A cluster-assisted nucleation mechanism responsible for the enhanced nucleation of silicon phase upon inoculation is proposed. Icosahedral (AlFeSi) clusters are speculated to evolve from the added Al–10Si–2Fe master alloy in Al–10Si melt, around which aggregations of silicon atoms form. Through a series of structural evolutions, these clusters transform into precursors of a silicon crystal. The subsequent formation of silicon particles is achieved by the agglomerations and attachments of these precursors and individual silicon atoms. This hypothesis is further consolidated by the increased characteristic temperatures of eutectic and the anomalous appearance of a high density of nanoscale particles, as well as the abnormal disappearance of Sr-induced twins in further inoculated silicon particles. The increased characteristic temperatures are strong indications of the enhanced nucleation of the silicon phase. The high density of nanoscale particles with an indeterminate crystal structure are the survivors of these precursors. In an Sr-modified and further inoculated sample, the formation of Sr-induced twins is consequently inhibited due to the participation of these precursors during the growth of silicon particles. Furthermore, based on the proposed nucleation mechanism, the dependence of eutectic cell size on Sr level is elucidated in detail

  14. Dose Escalation of Total Marrow Irradiation With Concurrent Chemotherapy in Patients With Advanced Acute Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Jeffrey Y.C., E-mail: jwong@coh.org [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States); Forman, Stephen; Somlo, George [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States); Rosenthal, Joseph [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States); Department of Pediatrics, City of Hope National Medical Center, Duarte, California (United States); Liu An; Schultheiss, Timothy; Radany, Eric [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California (United States); Palmer, Joycelynne [Department of Biostatistics, City of Hope National Medical Center, Duarte, California (United States); Stein, Anthony [Department of Hematology/Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, California (United States)

    2013-01-01

    Purpose: We have demonstrated that toxicities are acceptable with total marrow irradiation (TMI) at 16 Gy without chemotherapy or TMI at 12 Gy and the reduced intensity regimen of fludarabine/melphalan in patients undergoing hematopoietic cell transplantation (HCT). This article reports results of a study of TMI combined with higher intensity chemotherapy regimens in 2 phase I trials in patients with advanced acute myelogenous leukemia or acute lymphoblastic leukemia (AML/ALL) who would do poorly on standard intent-to-cure HCT regimens. Methods and Materials: Trial 1 consisted of TMI on Days -10 to -6, etoposide (VP16) on Day -5 (60 mg/kg), and cyclophosphamide (CY) on Day -3 (100 mg/kg). TMI dose was 12 (n=3 patients), 13.5 (n=3 patients), and 15 (n=6 patients) Gy at 1.5 Gy twice daily. Trial 2 consisted of busulfan (BU) on Days -12 to -8 (800 {mu}M min), TMI on Days -8 to -4, and VP16 on Day -3 (30 mg/kg). TMI dose was 12 (n=18) and 13.5 (n=2) Gy at 1.5 Gy twice daily. Results: Trial 1 had 12 patients with a median age of 33 years. Six patients had induction failures (IF), and 6 had first relapses (1RL), 9 with leukemia blast involvement of bone marrow ranging from 10%-98%, 5 with circulating blasts (24%-85%), and 2 with chloromas. No dose-limiting toxicities were observed. Eleven patients achieved complete remission at Day 30. With a median follow-up of 14.75 months, 5 patients remained in complete remission from 13.5-37.7 months. Trial 2 had 20 patients with a median age of 41 years. Thirteen patients had IF, and 5 had 1RL, 2 in second relapse, 19 with marrow blasts (3%-100%) and 13 with peripheral blasts (6%-63%). Grade 4 dose-limiting toxicities were seen at 13.5 Gy (stomatitis and hepatotoxicity). Stomatitis was the most frequent toxicity in both trials. Conclusions: TMI dose escalation to 15 Gy is possible when combined with CY/VP16 and is associated with acceptable toxicities and encouraging outcomes. TMI dose escalation is not possible with BU/VP16 due to

  15. Total skin electron beam therapy for cutaneous T-cell lymphoma: A nationwide cohort study from Denmark

    International Nuclear Information System (INIS)

    Lindahl, Lise M.; Iversen, Lars; Kamstrup, Maria R.; Gniadecki, Robert; Petersen, Peter M.; Specht, Lena; Wiren, Johan; Fenger-Groen, Morten

    2011-01-01

    Background. Total skin electron beam therapy (TSEBT) is an effective palliative treatment for cutaneous T-cell lymphoma (CTCL). In the present study we reviewed the clinical response to TSEBT in Danish patients with CTCL. Material and methods. This retrospective study included 35 patients with CTCL treated with TSEBT in Denmark from 2001 to 2008 and followed for a median time of 7.6 months (range 3 days-3.7 years). Twenty five patients were treated with high-dose (30 Gy) and 10 patients in a protocol with low-dose (4 Gy) TSEBT. Results. Patients treated with low-dose therapy had inadequate response to treatment compared to patients treated with high-dose. Consequently the study with low-dose was discontinued and published. In patients treated with high-dose the overall response rate was 100%. Complete response (CR) rate was 68% and CR occurred after a median time of 2.1 months (range 1.8 months - 2.0 years). We found no difference in CR rate in patients with T2 (66.7%) and T3 disease (78.6%) (p = 0.64). Following CR 82.4% relapsed at a median time of four months (range 12 days-11.5 months). Relapse-free-survival was similar in patients with T2 and T3 disease (p 0.77). Progressive disease (PD) was experienced in 28.0% and the median time to PD was 9.0 months (range 4.6-44.3 months). Overall progression-free survival was 95.3%, 72.1% and 64.1% after 0.5-, 1- and 2-years. Effects of initial therapy on TSEBT treatment response and side effects to TSEBT were also analyzed. Conclusion. In conclusion, the present study confirms that high-dose TSEBT is an effective, but generally not a curative therapy in the management of CTCL. High-dose treatment yielded significantly better results than low-dose treatment with 4 Gy. TSEBT offers significant palliation in most patients when other skin-directed or systemic treatments have failed

  16. [Loss of total 5-methylcytosine from the genome during cell culture aging coincides with the Hayflick limit].

    Science.gov (United States)

    Mazin, A L

    1993-01-01

    Analyzing the data about the age-related 5-methylcytosine (5mC) loss from DNA of cell cultures, the following conclusions have been made: 1. The rate of 5mC loss from DNA does not depend on the cell donor age; it remains constant during the logarithmic phase of cell growth, and may vary significantly in different cell lines. 2. The rate is inversely proportional to their Hayflick limit and to the species lifespan of cell donors. 3. In immortal cell lines the 5mC content in DNA is stable or increases with aging. 4. Hayflick limit estimations coincide with or are lower than the number of cell population doublings that corresponds to all 5mC loss from cell genome. A simple and fast method has been proposed for Hayflick limit prognostication by analysis of the rate of DNA hypomethylation. It may be used for early diagnosis of precrisis and immortal cell lines. Evidence has been obtained that age-dependent 5mC loss from DNA is the result of accumulating 5mC-->T+C substitutions that occur during DNA methylation in every cell division. The loss of all genomic 5mC residues during the lifespan may correspond to accumulation of about 3 x 10(6) 5mC-->T transitions or, on average, one mutation per gene. This may be one of the main reasons of the "catastrophe of errors" and cessation of cell proliferation. It is calculated that the rate of 5mC-->T transitions in normal cells may be 2.3 x 10(-5) per site in each cell doubling in human, 6 x 10(-5) in hamster, and 4.6 x 10(-4) in mouse. DNA methylation as a generator of mutations may be a "counter" of cell divisions and thus be one of the molecular mechanisms of the Hayflick phenomenon. The conclusion is made that the DNA methylation system may be considered as a genetically programmed mechanism for accumulating mutations during cell aging.

  17. Self-organized strain engineering on GaAs (311)B : template formation for quantum dot nucleation control

    NARCIS (Netherlands)

    Gong, Q.; Nötzel, R.; Hamhuis, G.J.; Eijkemans, T.J.; Wolter, J.H.

    2002-01-01

    A matrix of closely packed cells develops during molecular-beam epitaxy of In/sub 0.35/Ga/sub 0.65/As on GaAs (311)B, due to strain-driven growth instability. The established lateral strain distribution generates a unique template that controls the nucleation and growth of InAs quantum dots (QDs).

  18. Experimental study of ion-induced nucleation by radon decay

    International Nuclear Information System (INIS)

    He, F.; Hopke, P.K.

    1993-01-01

    In the environment, the presence of ions from natural radioactivity may increase the rate of new particle formation through ion-induced nucleation. A thermal diffusion cloud chamber (TDCC) has been built to experimentally study ion-induced nucleation where the ions are produced by gaseous radioactive sources. The critical supersaturation values and nucleation rates for methanol, ethanol, 1-propanol, and 1-butanol vapors on ions produced within the volume of the chamber by alpha decay of 222 Rn have been measured quantitatively at various radioactivity concentrations and supersaturations. The presence of ion tracks and the effect of an external electric field were also investigated. The alpha tracks and ion-induced nucleation formed by 222 Rn decay become visible at the critical supersaturation that is below the value needed for homogeneous nucleation. At this supersaturation, the nucleation rates increase substantially with increasing 222 Rn at low activity concentrations, but attain limiting values at higher concentrations. The experimental results indicate that the ionization by radon decay will promote ion-cluster formation and lower the free energy barriers. The formation of visible droplets is strongly dependent on the supersaturation. This study also confirms that the external electric field has a significant effect on the observed rates of nucleation

  19. Nucleation and Growth Kinetics from LaMer Burst Data.

    Science.gov (United States)

    Chu, Daniel B K; Owen, Jonathan S; Peters, Baron

    2017-10-12

    In LaMer burst nucleation, the individual nucleation events happen en masse, quasi-simultaneously, and at nearly identical homogeneous conditions. These properties make LaMer burst nucleation important for applications that require monodispersed particles and also for theoretical analyses. Sugimoto and co-workers predicted that the number of nuclei generated during a LaMer burst depends only on the solute supply rate and the growth rate, independent of the nucleation kinetics. Some experiments confirm that solute supply kinetics control the number of nuclei, but flaws in the original theoretical analysis raise questions about the predicted roles of growth and nucleation kinetics. We provide a rigorous analysis of the coupled equations that govern concentrations of nuclei and solutes. Our analysis confirms that the number of nuclei is largely determined by the solute supply and growth rates, but our predicted relationship differs from that of Sugimoto et al. Moreover, we find that additional nucleus size dependent corrections should emerge in systems with slow growth kinetics. Finally, we show how the nucleation kinetics determine the particle size distribution. We suggest that measured particle size distributions might therefore provide ways to test theoretical models of homogeneous nucleation kinetics.

  20. Heterogeneous nucleation of protein crystals on fluorinated layered silicate.

    Directory of Open Access Journals (Sweden)

    Keita Ino

    Full Text Available Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface.

  1. Alteration of sensitivity of intratumor quiescent and total cells to γ-rays following thermal neutron irradiation with or without 10B-compound

    International Nuclear Information System (INIS)

    Masunaga, Shin-ichiro; Ono, Koji; Suzuki, Minoru; Sakurai, Yoshinori; Kobayashi, Tooru; Takagaki, Masao; Kinashi, Yuko; Akaboshi, Mitsuhiko

    2000-01-01

    Purpose: Changes in the sensitivity of intratumor quiescent (Q) and total cells to γ-rays following thermal neutron irradiation with or without 10 B-compound were examined. Methods and Materials: 5-Bromo-2'-deoxyuridine (BrdU) was injected to SCC VII tumor-bearing mice intraperitoneally 10 times to label all the proliferating (P) tumor cells. As priming irradiation, thermal neutrons alone or thermal neutrons with 10 B-labeled sodium borocaptate (BSH) or dl-p-boronophenylalanine (BPA) were administered. The tumor-bearing mice then received a series of γ-ray radiation doses, 0 through 24 h after the priming irradiation. During this period, no BrdU was administered. Immediately after the second irradiation, the tumors were excised, minced, and trypsinized. Following incubation of tumor cells with cytokinesis blocker, the micronucleus (MN) frequency in cells without BrdU labeling (= Q cells at the time of priming irradiation) was determined using immunofluorescence staining for BrdU. The MN frequency in the total (P + Q) tumor cells was determined from the tumors that were not pretreated with BrdU before the priming irradiation. To determine the BrdU-labeled cell ratios in the tumors at the time of the second irradiation, each group also included mice that were continuously administered BrdU until just before the second irradiation using mini-osmotic pumps which had been implanted subcutaneously 5 days before the priming irradiation. Results: In total cells, during the interval between the two irradiations, the tumor sensitivity to γ-rays relative to that immediately after priming irradiation decreased with the priming irradiation ranking in the following order: thermal neutrons only > thermal neutrons with BSH > thermal neutrons with BPA. In contrast, in Q cells, during that time the sensitivity increased in the following order: thermal neutrons only 10 B-compound, especially BPA, in thermal neutron irradiation causes the recruitment from the Q to P population

  2. Bone marrow transplantation across major histocompatibility barriers in mice. II. T cell requirement for engraftment in total lymphoid irradiation-conditioned recipients

    International Nuclear Information System (INIS)

    Vallera, D.A.; Soderling, C.C.; Carlson, G.J.; Kersey, J.H.

    1982-01-01

    Studies were undertaken to examine the role of T lymphocytes in engraftment of bone marrow (BM) in animals conditioned with total lymphoid irradiation (TLI) prior to transplantation across major histocompatibility barriers. Donor BM (added as a source of lymphohematopoietic stem cells) and spleen cells (added as a source of graft-versus-host disease (GVHD)-causing cells) were pretreated in vitro with monoclonal anti-Thy-1.2 plus complement (C). T cell-depleted grafts were then give to allogeneic mice conditioned with 900 rad of single dose TLI plus cyclophosphamide (CY). These mice did not engraft. Even in the absence of added spleen cells, elimination of the small T cell population from donor BM grafts prevented engraftment compared with animals that received the same conditioning regimen and untreated donor cells. These control animals demonstrated uniform evidence of engraftment about 1 month after transplantation. Similar findings were reported when recipients were conditioned with fractionated 17 x 200-rad TLI. In TLI plus CY-conditional recipients, we have also observed that increasing the donation of treated bone marrow cells still did not result in significant engraftment. Furthermore, graft failure in mice receiving normal dosages of anti-Thy-1.2 plus C-treated donor cells was not a strain-restricted phenomenon. Moreover, removal of bone marrow T cells with monoclonal anti-Lyt-1 plus complement also resulted in graft failure in TLI-conditioned recipients. In contrast to TLI conditioning, when Thy-1.2 plus C-treated donor cells were given to recipients conditioned with total body irradiation (TBI), a high percentage of engraftment was demonstrated by an H-2 microcytotoxicity assay. Plausible mechanisms for there findings are discussed

  3. Binary nucleation kinetics. III. Transient behavior and time lags

    International Nuclear Information System (INIS)

    Wyslouzil, B.E.; Wilemski, G.

    1996-01-01

    Transient binary nucleation is more complex than unary because of the bidimensionality of the cluster formation kinetics. To investigate this problem qualitatively and quantitatively, we numerically solved the birth-death equations for vapor-to-liquid phase transitions. Our previous work showed that the customary saddle point and growth path approximations are almost always valid in steady state gas phase nucleation and only fail if the nucleated solution phase is significantly nonideal. Now, we demonstrate that in its early transient stages, binary nucleation rarely, if ever, occurs via the saddle point. This affects not only the number of particles forming but their composition and may be important for nucleation in glasses and other condensed mixtures for which time scales are very long. Before reaching the state of saddle point nucleation, most binary systems pass through a temporary stage in which the region of maximum flux extends over a ridge on the free energy surface. When ridge crossing nucleation is the steady state solution, it thus arises quite naturally as an arrested intermediate state that normally occurs in the development of saddle point nucleation. While the time dependent and steady state distributions of the fluxes and concentrations for each binary system are strongly influenced by the gas composition and species impingement rates, the ratio of nonequilibrium to equilibrium concentrations has a quasiuniversal behavior that is determined primarily by the thermodynamic properties of the liquid mixture. To test our quantitive results of the transient behavior, we directly calculated the time lag for the saddle point flux and compared it with the available analytical predictions. Although the analytical results overestimate the time lag by factors of 1.2-5, they should be adequate for purposes of planning experiments. We also found that the behavior of the saddle point time lag can indicate when steady state ridge crossing nucleation will occur

  4. Total algorithms

    NARCIS (Netherlands)

    Tel, G.

    We define the notion of total algorithms for networks of processes. A total algorithm enforces that a "decision" is taken by a subset of the processes, and that participation of all processes is required to reach this decision. Total algorithms are an important building block in the design of

  5. Nucleation and Crystal Growth of Organic-Inorganic Lead Halide Perovskites under Different Relative Humidity.

    Science.gov (United States)

    Gao, Hao; Bao, Chunxiong; Li, Faming; Yu, Tao; Yang, Jie; Zhu, Weidong; Zhou, Xiaoxin; Fu, Gao; Zou, Zhigang

    2015-05-06

    Organic-inorganic lead halide perovskite compounds are very promising materials for high-efficiency perovskite solar cells. But how to fabricate high-quality perovksite films under controlled humidity conditions is still an important issue due to their sensitivity to moisture. In this study, we investigated the influence of ambient humidity on crystallization and surface morphology of one-step spin-coated perovskite films, as well as the performance of solar cells based on these perovskite films. On the basis of experimental analyses and thin film growth theory, we conclude that the influence of ambient humidity on nucleation at spin-coating stage is quite different from that on crystal growth at annealing stage. At the spin-coating stage, high nucleation density induced by high supersaturation prefers to appear under anhydrous circumstances, resulting in layer growth and high coverage of perovskite films. But at the annealing stage, the modest supersaturation benefits formation of perovskite films with good crystallinity. The films spin-coated under low relative humidity (RH) followed by annealing under high RH show an increase of crystallinity and improved performance of devices. Therefore, a mechanism of fast nucleation followed by modest crystal growth (high supersaturation at spin-coating stage and modest supersaturation at annealing stage) is suggested in the formation of high-quality perovskite films.

  6. Nucleation and growth of polycrystalline SiC

    DEFF Research Database (Denmark)

    Kaiser, M.; Schimmel, S.; Jokubavicius, V.

    2014-01-01

    The nucleation and bulk growth of polycrystalline SiC in a 2 inch PVT setup using isostatic and pyrolytic graphite as substrates was studied. Textured nucleation occurs under near-thermal equilibrium conditions at the initial growth stage with hexagonal platelet shaped crystallites of 4H, 6H and 15......R polytypes. It is found that pyrolytic graphite results in enhanced texturing of the nucleating gas species. Reducing the pressure leads to growth of the crystallites until a closed polycrystalline SiC layer containing voids with a rough surface is developed. Bulk growth was conducted at 35 mbar Ar...

  7. Nacre biomineralisation: A review on the mechanisms of crystal nucleation.

    Science.gov (United States)

    Nudelman, Fabio

    2015-10-01

    The wide diversity of biogenic minerals that is found in nature, each with its own morphology, mechanical properties and composition, is remarkable. In order to produce minerals that are optimally adapted for their function, biomineralisation usually occurs under strict cellular control. This control is exerted by specialised proteins and polysaccharides that assemble into a 3-dimensional organic matrix framework, forming a microenvironment where mineral deposition takes place. Molluscs are unique in that they use a striking variety of structural motifs to build their shells, each made of crystals with different morphologies and different calcium carbonate polymorphs. Much of want is known about mollusc shell formation comes from studies on the nacreous layer, or mother-of-pearl. In this review, we discuss two existing models on the nucleation of aragonite crystals during nacre formation: heteroepitaxial nucleation and mineral bridges. The heteroepitaxial nucleation model is based on the identification of chemical functional groups and aragonite-nucleating proteins at the centre of crystal imprints. It proposes that during nacre formation, each aragonite tablet nucleates independently on a nucleation site that is formed by acidic proteins and/or glycoproteins adsorbed on the chitin scaffold. The mineral bridges model is based on the identification of physical connections between the crystals in a stack, which results in a large number of crystals across several layers sharing the same crystallographic orientation. These observations suggest that there is one nucleation event per stack of tablets. Once the first crystal nucleates and reaches the top interlamellar matrix, it continues growing through pores, giving rise to the next layer of nacre, subsequently propagating into a stack. We compare both models and propose that they work in concert to control crystal nucleation in nacre. De novo crystal nucleation has to occur at least once per stack of aligned crystals

  8. Nucleation at hardness indentations in cold rolled Al

    DEFF Research Database (Denmark)

    Xu, C.L.; Zhang, Yubin; Wu, G.L.

    2015-01-01

    Nucleation of recrystallization near hardness indentations has been investigated in slightly cold rolled high purity aluminium. Samples were cold rolled to 12% and 20% reductions in thickness and indentations were done with two different loads (500 g and 2000 g). The samples were annealed at 300 °C...... for 1 h and nuclei were identified. It is found that the indentations are preferential nucleation sites. With EBSD maps around indentation tips, the orientation relationship between nuclei and matrix is analyzed. Finally, effects of rolling reduction and indentation load on local misorientations...... and stored energy distributions and thus on nucleation are discussed....

  9. Non-self-averaging nucleation rate due to quenched disorder

    International Nuclear Information System (INIS)

    Sear, Richard P

    2012-01-01

    We study the nucleation of a new thermodynamic phase in the presence of quenched disorder. The quenched disorder is a generic model of both impurities and disordered porous media; both are known to have large effects on nucleation. We find that the nucleation rate is non-self-averaging. This is in a simple Ising model with clusters of quenched spins. We also show that non-self-averaging behaviour is straightforward to detect in experiments, and may be rather common. (fast track communication)

  10. Understanding nanoparticle-mediated nucleation pathways of anisotropic nanoparticles

    Science.gov (United States)

    Laramy, Christine R.; Fong, Lam-Kiu; Jones, Matthew R.; O'Brien, Matthew N.; Schatz, George C.; Mirkin, Chad A.

    2017-09-01

    Several seed-mediated syntheses of low symmetry anisotropic nanoparticles yield broad product distributions with multiple defect structures. This observation challenges the role of the nanoparticle precursor as a seed for certain syntheses and suggests the possibility of alternate nucleation pathways. Herein, we report a method to probe the role of the nanoparticle precursor in anisotropic nanoparticle nucleation with compositional and structural 'labels' to track their fate. We use the synthesis of gold triangular nanoprisms (Au TPs) as a model system. We propose a mechanism in which, rather than acting as a template, the nanoparticle precursor catalyzes homogenous nucleation of Au TPs.

  11. Physical characterization of diesel exhaust nucleation mode particles

    Energy Technology Data Exchange (ETDEWEB)

    Lahde, T.

    2013-11-01

    An increasing concern of the adverse health effects of aerosol particles is forcing the combustion engine industry to develop engines with lower particle emissions. The industry has put most of their efforts into soot control and has achieved a significant reduction in diesel exhaust particle mass. Nevertheless, it is not clear that the large particles, dominating the mass, cause the harmfulness of the exhaust particles in the biological interaction. Nowadays, the harmful potential of diesel exhaust particles often connects with the particle surface area, and the view has turned to particle number below 100 nm size range. Unfortunately, the achieved low exhaust particle mass does not necessarily imply a low particle number. This text focuses on the physical characteristics of diesel exhaust nucleation model particles. The volatility characteristics and the electrical charge state of the particles are studied first. Second, the relation between the nonvolatile nucleation mode emissions and the soot, the nitrogen oxide (NO{sub x}) emissions and the engine parameters are covered. The nucleation mode particles had distinctively different physical characteristics with different after-treatment systems. The nucleation mode was volatile and electrically neutral with a diesel particle filter after-treatment system. Without an after-treatment system or with an after-treatment system with low particle removal efficiency, the nucleation mode was partly nonvolatile and included an electrical charge. The difference suggests different formation routes for the nucleation particles with different after-treatment systems. The existence of the nonvolatile nucleation mode particles also affected the soot mode charge state. The soot charge state was positively biased when the nonvolatile nucleation mode was detected but slightly negatively biased when the nonvolatile nucleation mode was absent. The nonvolatile nucleation mode was always negatively biased. This electrical charge

  12. Rescue by peripheral blood mononuclear cells in dogs from bone marrow failure after total-body irradiation

    International Nuclear Information System (INIS)

    Zander, A.R.; Gray, K.N.; Hester, J.P.

    1984-01-01

    In order to determine the minimum dose of buffy coat cells necessary to achieve hematopoietic rescue following supralethal irradiation, mongrel dogs under general anesthesia were subjected to leukacytapheresis using three different techniques of cell separation. The buffy coats were frozen with dimethylsulfoxide and stored at -196 degrees C until transfused. Sixteen dogs were irradiated with 800 rads and were supported with antibiotics and transfusions of irradiated homologous blood. They were transfused with the frozen and thawed buffy coat cells, and, if they survived, they were followed for 100 days, sacrificed, and their tissues studied. The mean yield of mononuclear cells during leukocytapheresis ranged from 4.1 +/- 2.0 X 10(9) (mean +/- SD) to 6.0 +/- 4.0 X 10(9) for the three leukacytapheresis methods; one technique was not as satisfactory as the other two. Six of the 16 dogs fully recovered with evidence of marrow rescue; however, only one had a dose of mononuclear cells less than 11.1 X 10(9). These data indicate that seven to 17 leukacytapheresis procedures would be required to reconstitute a 70 kilogram patient. These preliminary findings suggest that, because the yields of transplantable cells with current technology are not adequate, the transplantation potential of buffy coat cells exposed to mobilizing agents should be evaluated

  13. Thymic irradiation inhibits the rapid recovery of TH1 but not TH2-like functions of CD4+ T cells after total lymphoid irradiation

    International Nuclear Information System (INIS)

    Bass, H.; Adkins, B.; Strober, S.

    1991-01-01

    Four to six weeks after total lymphoid irradiation (TLI), there is a selective deficit in the CD4+ T cells which secrete IL-2, proliferate in the MLR, and induce GVHD (Th1-like functions). A similar deficit in CD4+ T cells which secrete IL-4 and help antibody responses (Th2-like functions) is not observed. In the present study, shielding of the thymus with lead during TLI increased the Th1-like functions of CD4+ cells. Mice without thymus shields showed a marked selective reduction in the medullary stromal cells identified with the monoclonal antibody, MD1, and the severe reduction was prevented with thymus shields. Thus, shielding the thymus prevents the depletion of thymic medullary stromal cells and allows for a rapid recovery of Th1-like functions in the mouse spleen after TLI. Th2-like functions recover rapidly after TLI whether or not the thymus is irradiated

  14. Saturation and nucleation in hot nuclear systems

    International Nuclear Information System (INIS)

    Deangelis, A.R.

    1990-07-01

    We investigate nuclear fragmentation in a supersaturated system using classical nucleation theory. This allows us to go outside the normally applied constraint of chemical equilibrium. The system is governed by a virial equation of state, which we use to find an expression for the density as a function of pressure and temperature. The evolution of the system is discussed in terms of the phase diagram. Corrections are included to account for the droplet surface and all charges contained in the system. Using this model we investigate and discuss the effects of temperature and saturation, and compare the results to those of other models of fragmentation. We also discuss the limiting temperatures of the system for the cases with and without chemical equilibrium. We find that large nuclei will be formed in saturated systems, even above the limiting temperature as previously defined. We also find that saturation and temperature dominate surface and Coulomb effects. The effects are quite large, thus even a qualitative inspection of the yields may give an indication of the conditions during fragmentation

  15. A conducting polymer nucleation scheme for efficient solid-state supercapacitors on paper

    KAUST Repository

    Kurra, Narendra; Park, Jihoon; Alshareef, Husam N.

    2014-01-01

    In this study, a thin nucleation layer is used to tune the morphology of conducting polymer electrodes and to optimize the performance of paper based solid-state supercapacitors. It is found that using an acid-treated poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) nucleation layer, prior to poly(3,4-ethylenedioxythiophene), PEDOT, electrochemical deposition, gives 5-6 times higher areal capacitance compared to a gold metal nucleation layer. Specifically, PEDOT supercapacitors with a high volumetric capacitance of 327 F cm-3, higher than any other PEDOT based supercapacitors reported in the literature, is achieved on the PEDOT:PSS nucleation layer; for the same devices, an areal capacitance of 242 mF cm-2 and an energy density of 14.5 mW h cm-3 at a power density of 350 mW cm-3 are obtained. Furthermore, these optimized PEDOT/PEDOT:PSS/paper electrodes are employed to fabricate solid-state supercapacitors using aqueous and ion gel electrolytes, with 32 and 11 mF cm-2 cell capacitance, respectively. The solid-state PEDOT device showed an energy density of 1.5 mW h cm-3 (normalised to the volume of the whole cell, including both the electrodes and the electrolyte), which is higher than the best reported ppy/paper (E = 1 mW h cm-3) and PAni/pencil/paper (E = 0.32 mW h cm-3) solid-state devices. The cycling performance showed that capacitance retention up to 80% is achieved after 10000 cycles. This journal is

  16. A conducting polymer nucleation scheme for efficient solid-state supercapacitors on paper

    KAUST Repository

    Kurra, Narendra

    2014-08-19

    In this study, a thin nucleation layer is used to tune the morphology of conducting polymer electrodes and to optimize the performance of paper based solid-state supercapacitors. It is found that using an acid-treated poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) nucleation layer, prior to poly(3,4-ethylenedioxythiophene), PEDOT, electrochemical deposition, gives 5-6 times higher areal capacitance compared to a gold metal nucleation layer. Specifically, PEDOT supercapacitors with a high volumetric capacitance of 327 F cm-3, higher than any other PEDOT based supercapacitors reported in the literature, is achieved on the PEDOT:PSS nucleation layer; for the same devices, an areal capacitance of 242 mF cm-2 and an energy density of 14.5 mW h cm-3 at a power density of 350 mW cm-3 are obtained. Furthermore, these optimized PEDOT/PEDOT:PSS/paper electrodes are employed to fabricate solid-state supercapacitors using aqueous and ion gel electrolytes, with 32 and 11 mF cm-2 cell capacitance, respectively. The solid-state PEDOT device showed an energy density of 1.5 mW h cm-3 (normalised to the volume of the whole cell, including both the electrodes and the electrolyte), which is higher than the best reported ppy/paper (E = 1 mW h cm-3) and PAni/pencil/paper (E = 0.32 mW h cm-3) solid-state devices. The cycling performance showed that capacitance retention up to 80% is achieved after 10000 cycles. This journal is

  17. Two types of T helper cells in mice: Differences in cellular immune functions and cytokine secretion - selective reduction of one type after total lymphoid irradiation

    International Nuclear Information System (INIS)

    Bass, H.Z.

    1989-01-01

    As observed from a large panel of mouse T helper clones, there are at least two subsets of CD4 + T cells that both differ in function and demonstrate distinct patterns of cytokine secretion after antigen or mitogen stimulation. Th1 cells synthesize IL-2, INF-γ and lymphotoxin. They produce a DTH reaction in the footpads of naive mice. In addition, Th1 cells are required for the generation of CTL, and they appear to augment IgG2a antibody production. In contrast, by secreting IL-4, IL-5, and IL-6, Th2 cells play an essential role in humoral immunity. TLI consists of high dose, fractionated irradiation delivered selectively to the major lymphoid tissues. Four to six weeks after TLI, the CD4 + cells of the treated mice (counted as a percentage of the total spleen lymphocytes) recover to the similar levels as those in normal BALB/c mice. These CD4 + cells can help normal syngeneic B cells to produce a vigorous antibody response to TNP-KLH in adoptive cell transfer experiments, but the same cells are inactive in the MLR, and they fail to transfer DTH in TNP-KLH primed syngeneic BALB/c mice

  18. [Effect of total glucosides of peony on expression and DNA methylation status of ITGAL gene in CD4(+) T cells of systemic lupus erythematosus].

    Science.gov (United States)

    Zhao, Ming; Liang, Gongping; Luo, Shuangyan; Lu, Qianjin

    2012-05-01

    To investigate the effect of total glucosides of peony (TGP) on expression and DNA methylation status of ITGAL gene (CD11a) in CD4(+) T cells from patients with systemic lupus erythematosus (SLE). CD4(+) T cells were isolated by positive selection using CD4 beads. CD4(+) T cells were treated by TGP at 0, 62.5, 312.5 and 1562.5 mg/L for 48 h. The MTT method was used to assess cell viability; mRNA expression level was measured by realtime-PCR; protein level of CD11a was measured by flow cytometric analysis; DNA methylation status was assayed by bisulfite sequencing. No significant change in cell viability was found in CD4(+) T cells among the different concentration groups (P>0.05). Compared with control, the mRNA and protein levels of ITGAL were down-regulated significantly in SLE CD4(+) T cells treated with TGP (1562.5 mg/L) (PTGP (1562.5 mg/L) treated CD4(+) T cells compared with control group (PTGP can repress CD11a gene expression through enhancing DNA methylation of ITGAL promoter in CD4(+) T cells from patients with SLE. This observation represents a preliminary step in understanding the mechanism of TGP in SLE therapy.

  19. Effect of different doses of aerobic exercise on total white blood cell (WBC and WBC subfraction number in postmenopausal women: results from DREW.

    Directory of Open Access Journals (Sweden)

    Neil M Johannsen

    Full Text Available BACKGROUND: Elevated total white blood cell (WBC count is associated with an increased risk of coronary heart disease and death. Aerobic exercise is associated with lower total WBC, neutrophil, and monocyte counts. However, no studies have evaluated the effect of the amount of aerobic exercise (dose on total WBC and WBC subfraction counts. PURPOSE: To examine the effects of 3 different doses of aerobic exercise on changes in total WBC and WBC subfraction counts and independent effects of changes in fitness, adiposity, markers of inflammation (IL-6, TNF-α, C-reactive protein, fasting glucose metabolism, and adiponectin. METHODS: Data from 390 sedentary, overweight/obese postmenopausal women from the DREW study were used in these analyses. Women were randomized to a non-exercise control group or one of 3 exercise groups: energy expenditure of 4, 8, or 12 kcal kg(-1⋅week(-1 (KKW for 6 months at an intensity of 50% VO2peak. RESULTS: A dose-dependent decrease in total WBC counts (trend P = 0.002 was observed with a significant decrease in the 12KKW group (-163.1±140.0 cells/µL; mean±95%CI compared with the control (138.6±144.7 cells/µL. A similar response was seen in the neutrophil subfraction (trend P = 0.001 with a significant decrease in the 12KKW group (-152.6±115.1 cells/µL compared with both the control and 4KKW groups (96.4±119.0 and 21.9±95.3 cells/µL, respectively and in the 8KKW group (-102.4±125.0 cells/µL compared with the control. When divided into high/low baseline WBC categories (median split, a dose-dependent decrease in both total WBCs (P = 0.003 and neutrophils (P<0.001 was observed in women with high baseline WBC counts. The effects of exercise dose on total WBC and neutrophil counts persisted after accounting for significant independent effects of change in waist circumference and IL-6. CONCLUSION: Aerobic exercise training reduces total WBC and neutrophil counts, in a dose-dependent manner, in

  20. Analysis of isothermal and cooling-rate-dependent immersion freezing by a unifying stochastic ice nucleation model

    Science.gov (United States)

    Alpert, Peter A.; Knopf, Daniel A.

    2016-02-01

    Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature, T, and relative humidity, RH, at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling-rate-dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nucleating particles (INPs) all have the same INP surface area (ISA); however, the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. Descriptions of ice active sites and variability of contact angles have been successfully formulated to describe ice nucleation experimental data in previous research; however, we consider the ability of a stochastic freezing model founded on classical nucleation theory to reproduce previous results and to explain experimental uncertainties and data scatter. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses parameters including the total number of droplets, Ntot, and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA-dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets

  1. Analysis of isothermal and cooling-rate-dependent immersion freezing by a unifying stochastic ice nucleation model

    Directory of Open Access Journals (Sweden)

    P. A. Alpert

    2016-02-01

    Full Text Available Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature, T, and relative humidity, RH, at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature and cooling-rate-dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nucleating particles (INPs all have the same INP surface area (ISA; however, the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. Descriptions of ice active sites and variability of contact angles have been successfully formulated to describe ice nucleation experimental data in previous research; however, we consider the ability of a stochastic freezing model founded on classical nucleation theory to reproduce previous results and to explain experimental uncertainties and data scatter. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses parameters including the total number of droplets, Ntot, and the heterogeneous ice nucleation rate coefficient, Jhet(T. This model is applied to address if (i a time and ISA-dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and

  2. Ice nucleation active bacteria in precipitation are genetically diverse and nucleate ice by employing different mechanisms.

    Science.gov (United States)

    Failor, K C; Schmale, D G; Vinatzer, B A; Monteil, C L

    2017-12-01

    A growing body of circumstantial evidence suggests that ice nucleation active (Ice + ) bacteria contribute to the initiation of precipitation by heterologous freezing of super-cooled water in clouds. However, little is known about the concentration of Ice + bacteria in precipitation, their genetic and phenotypic diversity, and their relationship to air mass trajectories and precipitation chemistry. In this study, 23 precipitation events were collected over 15 months in Virginia, USA. Air mass trajectories and water chemistry were determined and 33 134 isolates were screened for ice nucleation activity (INA) at -8 °C. Of 1144 isolates that tested positive during initial screening, 593 had confirmed INA at -8 °C in repeated tests. Concentrations of Ice + strains in precipitation were found to range from 0 to 13 219 colony forming units per liter, with a mean of 384±147. Most Ice + bacteria were identified as members of known and unknown Ice + species in the Pseudomonadaceae, Enterobacteriaceae and Xanthomonadaceae families, which nucleate ice employing the well-characterized membrane-bound INA protein. Two Ice + strains, however, were identified as Lysinibacillus, a Gram-positive genus not previously known to include Ice + bacteria. INA of the Lysinibacillus strains is due to a nanometer-sized molecule that is heat resistant, lysozyme and proteinase resistant, and secreted. Ice + bacteria and the INA mechanisms they employ are thus more diverse than expected. We discuss to what extent the concentration of culturable Ice + bacteria in precipitation and the identification of a new heat-resistant biological INA mechanism support a role for Ice + bacteria in the initiation of precipitation.

  3. S. pombe kinesins-8 promote both nucleation and catastrophe of microtubules.

    Directory of Open Access Journals (Sweden)

    Muriel Erent

    Full Text Available The kinesins-8 were originally thought to be microtubule depolymerases, but are now emerging as more versatile catalysts of microtubule dynamics. We show here that S. pombe Klp5-436 and Klp6-440 are non-processive plus-end-directed motors whose in vitro velocities on S. pombe microtubules at 7 and 23 nm s(-1 are too slow to keep pace with the growing tips of dynamic interphase microtubules in living S. pombe. In vitro, Klp5 and 6 dimers exhibit a hitherto-undescribed combination of strong enhancement of microtubule nucleation with no effect on growth rate or catastrophe frequency. By contrast in vivo, both Klp5 and Klp6 promote microtubule catastrophe at cell ends whilst Klp6 also increases the number of interphase microtubule arrays (IMAs. Our data support a model in which Klp5/6 bind tightly to free tubulin heterodimers, strongly promoting the nucleation of new microtubules, and then continue to land as a tubulin-motor complex on the tips of growing microtubules, with the motors then dissociating after a few seconds residence on the lattice. In vivo, we predict that only at cell ends, when growing microtubule tips become lodged and their growth slows down, will Klp5/6 motor activity succeed in tracking growing microtubule tips. This mechanism would allow Klp5/6 to detect the arrival of microtubule tips at cells ends and to amplify the intrinsic tendency for microtubules to catastrophise in compression at cell ends. Our evidence identifies Klp5 and 6 as spatial regulators of microtubule dynamics that enhance both microtubule nucleation at the cell centre and microtubule catastrophe at the cell ends.

  4. Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2008-10-01

    Full Text Available The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of Snomax™ were investigated in the temperature range between −5 and −15°C. Water suspensions of these bacteria were directly sprayed into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of −5.7°C. At this temperature, about 1% of the Snomax™ cells induced immersion freezing of the spray droplets before the droplets evaporated in the cloud chamber. The living cells didn't induce any detectable immersion freezing in the spray droplets at −5.7°C. After evaporation of the spray droplets the bacterial cells remained as aerosol particles in the cloud chamber and were exposed to typical cloud formation conditions in experiments with expansion cooling to about −11°C. During these experiments, the bacterial cells first acted as cloud condensation nuclei to form cloud droplets. Then, only a minor fraction of the cells acted as heterogeneous ice nuclei either in the condensation or the immersion mode. The results indicate that the bacteria investigated in the present study are mainly ice active in the temperature range between −7 and −11°C with an ice nucleation (IN active fraction of the order of 10−4. In agreement to previous literature results, the ice nucleation efficiency of Snomax™ cells was much larger with an IN active fraction of 0.2 at temperatures around −8°C.

  5. Microlayer Topology And Bubble Growth In Nucleate Boiling

    Science.gov (United States)

    Jawurek, H. H.; Macgregor, H. G.; Bodenheimer, J. S.

    1987-09-01

    During nucleate boiling thin liquid films (nicrolayers) form beneath the base of bubbles and evaporate into the bubble interiors. A technique is presented which permits the simultaneous determination of microlayer topology and the contribution of microlayer evaporation to bubble growth. Isolated-bubble boiling takes place on an electrically heated, transparent tin-oxide coating deposited on a glass plate, the latter forming the floor of a vessel. With coherent Claser) illumination from beneath, the microlayers reflect fringe patterns similar to Newton's rings. Owing to the rapid evaporation of the layers (the process is completed within milliseconds) the fringes are in rapid motion and are recorded by eine photography at some 4 000 frames per second and exposure times of 50 μs. The resulting interferograms provide details of microlayer shape and thickness versus time, and thus evaporation rate. Simultaneously, and on the same film, bubble profiles (and thus volumes) are obtained under white light illumination. The two bubble images are manipulated by mirrors and lenses so as to appear side by side on the same frame of film, the fringes magnified and the profiles reduced. Sample results for methanol boiling at a pressure of 58.5 kPa and with the liquid bulk at saturation temperature, are presented. Under such conditions microlayer evaporation accounts for 37 per cent of the total bubble volume at detachment.

  6. Latent heat transport and microlayer evaporation in nucleate boiling

    International Nuclear Information System (INIS)

    Jawurek, H.H.

    1977-08-01

    Part 1 of this work provides a broad overview and, where possible, a quantitative assessment of the complex physical processes which together constitute the mechanism of nucleate boiling heat transfer. It is shown that under a wide range of conditions the primary surface-to-liquid heat flows within an area of bubble influence are so redistributed as to manifest themselves predominantly as latent heat transport, that is, as vaporisation into attached bubbles. Part 2 deals in greater detail with one of the component processes of latent heat transport, namely microlayer evaporation. A literature review reveals the need for synchronised records of microlayer geometry versus time and of normal bubble growth and departure. An apparatus developed to provide such records is described. High-speed cine interference photography from beneath and through a transparent heating surface provided details of microlayer geometry and an image reflection system synchronised these records with the bubble profile views. Results are given for methanol and ethanol boiling at sub-atmospheric pressures and at various heat fluxes and bulk subcoolings. In all cases it is found that microlayers were of sub-micron thickness, that microlayer thinning was restricted to the inner layer edge (with the thickness elsewhere remaining constant or increasing with time) and that the contribution of this visible evaporation to the total vapour flow into bubbles was negligible. The observation of thickening towards the outer microlayer edge, however, demonstrates that a liquid replenishment flow occurred simultaneously with the evaporation process

  7. Frequencies of micro-nucleated lymphocytes and Epstein-Barr virus contamination in Altay region residents living near the Semipalatinsk atomic testing ground

    International Nuclear Information System (INIS)

    Ilyinskikh, N.N.; Ilyinskikh, E.N.; Yurkin, A.Yu.; Ilyinskikh, I.N.

    2003-01-01

    We have assessed frequencies of micro-nucleated lymphocytes in 3036 individuals living in 16 settlements in the west of the Altay region. Among the settlements the majority of individuals with significantly high frequencies of micro-nucleated lymphocytes were detected in settlements adjacent to the Semipalatinsk atomic testing ground (SATG). The most considerable genome instability was found in the individuals born in the period of intensive testing on the SATG (from 1949 to 1962). Moreover, we have determined that the residents of the settlements adjacent to the SATG have significantly high levels of antibodies to potentially oncogenic Epstein-Barr virus besides high frequencies of micro-nucleated lymphocytes. The considerable Epstein-Barr virus contamination among the residents in the radiation polluted zone around the SATG was supposed to be caused by immunodeficiency disorders in these individuals and induce high frequencies of micro-nucleated cells. (author)

  8. Volatile properties of atmospheric aerosols during nucleation events ...

    Indian Academy of Sciences (India)

    J. Earth Syst. ... position of nucleated particles, cloud condensa- ... the air sample heated by heating section, and (c) temperature profile insid