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Sample records for biological mechanisms leading

  1. Lead levels in some biological samples of auto-mechanics in Abeokuta, Nigeria.

    Science.gov (United States)

    Babalola, O O; Ojo, L O; Aderemi, M O

    2005-12-01

    Lead levels were determined in the blood, scalp hair and fingernails of 38, all male auto-mechanics (aged 18-45 years) from Abeokuta, South-western Nigeria. The subjects were classified into four sub-groups based on the period of exposure namely: 1-5, 6-10, 11-15, and >16 years. Thirty-two occupationally unexposed subjects (mainly office workers) served as the control. The weight, height and body mass indexes of all subjects were noted, in addition to other information obtained through structured questionnaire. The mean values of blood lead (BPb), hair lead (HPb) and fingernail lead (NPb) of the occupationally exposed subjects (n=38) were 48.50 +/- 9.08 microg/dL, 17.75 +/- 5.16 microg/g, and 5.92 +/- 3.30 microg/g respectively, while the corresponding mean values for these parameters in the control subjects (n = 32) were 33.(,5 +/- 10.09 microg/dL, 14.30 +/- 5.90 microg/g and 5.31 +/- 2.77 microg/g respectively. The differences in BPb and HPb levels of the two groups were statistically significant (P <0.05 and P <0.01 respectively), while that of NPb was not significant. The levels of lead in the biological samples appeared to have no relationship with the number of years on the job. From these results, it was obvious that the higher levels of lead in the biological samples of test subjects, compared with those of the controls were from environmental sources.

  2. Is synthetic biology mechanical biology?

    Science.gov (United States)

    Holm, Sune

    2015-12-01

    A widespread and influential characterization of synthetic biology emphasizes that synthetic biology is the application of engineering principles to living systems. Furthermore, there is a strong tendency to express the engineering approach to organisms in terms of what seems to be an ontological claim: organisms are machines. In the paper I investigate the ontological and heuristic significance of the machine analogy in synthetic biology. I argue that the use of the machine analogy and the aim of producing rationally designed organisms does not necessarily imply a commitment to mechanical biology. The ideal of applying engineering principles to biology is best understood as expressing recognition of the machine-unlikeness of natural organisms and the limits of human cognition. The paper suggests an interpretation of the identification of organisms with machines in synthetic biology according to which it expresses a strategy for representing, understanding, and constructing living systems that are more machine-like than natural organisms.

  3. Disrupted Signaling through the Fanconi Anemia Pathway Leads to Dysfunctional Hematopoietic Stem Cell Biology: Underlying Mechanisms and Potential Therapeutic Strategies

    Science.gov (United States)

    Geiselhart, Anja; Lier, Amelie; Walter, Dagmar; Milsom, Michael D.

    2012-01-01

    Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome. FA patients suffer to varying degrees from a heterogeneous range of developmental defects and, in addition, have an increased likelihood of developing cancer. Almost all FA patients develop a severe, progressive bone marrow failure syndrome, which impacts upon the production of all hematopoietic lineages and, hence, is thought to be driven by a defect at the level of the hematopoietic stem cell (HSC). This hypothesis would also correlate with the very high incidence of MDS and AML that is observed in FA patients. In this paper, we discuss the evidence that supports the role of dysfunctional HSC biology in driving the etiology of the disease. Furthermore, we consider the different model systems currently available to study the biology of cells defective in the FA signaling pathway and how they are informative in terms of identifying the physiologic mediators of HSC depletion and dissecting their putative mechanism of action. Finally, we ask whether the insights gained using such disease models can be translated into potential novel therapeutic strategies for the treatment of the hematologic disorders in FA patients. PMID:22675615

  4. Mechanical Biological Treatment

    DEFF Research Database (Denmark)

    Bilitewski, B-; Oros, Christiane; Christensen, Thomas Højlund

    2011-01-01

    The basic processes and technologies of composting and anaerobic digestion, as described in the previous chapters, are usually used for specific or source-separated organic waste flows. However, in the 1990s mechanical biological waste treatment technologies (MBT) were developed for unsorted...... or residual waste (after some recyclables removed at the source). The concept was originally to reduce the amount of waste going to landfill, but MBT technologies are today also seen as plants recovering fuel as well as material fractions. As the name suggests the technology combines mechanical treatment...... technologies (screens, sieves, magnets, etc.) with biological technologies (composting, anaerobic digestion). Two main technologies are available: Mechanical biological pretreatment (MBP), which first removes an RDF fraction and then biologically treats the remaining waste before most of it is landfilled...

  5. Mechanics rules cell biology

    Directory of Open Access Journals (Sweden)

    Wang James HC

    2010-07-01

    Full Text Available Abstract Cells in the musculoskeletal system are subjected to various mechanical forces in vivo. Years of research have shown that these mechanical forces, including tension and compression, greatly influence various cellular functions such as gene expression, cell proliferation and differentiation, and secretion of matrix proteins. Cells also use mechanotransduction mechanisms to convert mechanical signals into a cascade of cellular and molecular events. This mini-review provides an overview of cell mechanobiology to highlight the notion that mechanics, mainly in the form of mechanical forces, dictates cell behaviors in terms of both cellular mechanobiological responses and mechanotransduction.

  6. Quantum Mechanics predicts evolutionary biology.

    Science.gov (United States)

    Torday, J S

    2018-07-01

    Nowhere are the shortcomings of conventional descriptive biology more evident than in the literature on Quantum Biology. In the on-going effort to apply Quantum Mechanics to evolutionary biology, merging Quantum Mechanics with the fundamentals of evolution as the First Principles of Physiology-namely negentropy, chemiosmosis and homeostasis-offers an authentic opportunity to understand how and why physics constitutes the basic principles of biology. Negentropy and chemiosmosis confer determinism on the unicell, whereas homeostasis constitutes Free Will because it offers a probabilistic range of physiologic set points. Similarly, on this basis several principles of Quantum Mechanics also apply directly to biology. The Pauli Exclusion Principle is both deterministic and probabilistic, whereas non-localization and the Heisenberg Uncertainty Principle are both probabilistic, providing the long-sought after ontologic and causal continuum from physics to biology and evolution as the holistic integration recognized as consciousness for the first time. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Bioinspiration: applying mechanical design to experimental biology.

    Science.gov (United States)

    Flammang, Brooke E; Porter, Marianne E

    2011-07-01

    The production of bioinspired and biomimetic constructs has fostered much collaboration between biologists and engineers, although the extent of biological accuracy employed in the designs produced has not always been a priority. Even the exact definitions of "bioinspired" and "biomimetic" differ among biologists, engineers, and industrial designers, leading to confusion regarding the level of integration and replication of biological principles and physiology. By any name, biologically-inspired mechanical constructs have become an increasingly important research tool in experimental biology, offering the opportunity to focus research by creating model organisms that can be easily manipulated to fill a desired parameter space of structural and functional repertoires. Innovative researchers with both biological and engineering backgrounds have found ways to use bioinspired models to explore the biomechanics of organisms from all kingdoms to answer a variety of different questions. Bringing together these biologists and engineers will hopefully result in an open discourse of techniques and fruitful collaborations for experimental and industrial endeavors.

  8. News: Synthetic biology leading to specialty chemicals

    Science.gov (United States)

    Synthetic biology can combine the disciplines of biology, engineering, and chemistry productively to form molecules of great scientific and commercial value. Recent advances in the new field are explored for their connection to new tools that have been used to elucidate productio...

  9. News: Synthetic biology leading to specialty chemicals ...

    Science.gov (United States)

    Synthetic biology can combine the disciplines of biology, engineering, and chemistry productively to form molecules of great scientific and commercial value. Recent advances in the new field are explored for their connection to new tools that have been used to elucidate production pathways to a wide variety of chemicals generated by microorganisms. The selection and enhancement of microbiological strains through the practice of strain engineering enables targets of design, construction, and optimization. This news column aspires to cover recent literature relating to the development and understanding of clean technology.

  10. Mechanics of biological polymer composites

    Science.gov (United States)

    Lomakin, Joseph

    2009-12-01

    displayed a darker coloration and significantly increased n of 0.0470.004, suggesting both cuticles to be less cross-linked, a finding consistent with reduced beta-alanine metabolism. Suppression of the tanning enzyme laccase2 (TcLac2) resulted in a pale cuticle with an n of 0.043+/-0.005, implicating laccases in the formation of both pigments and cross-links during sclerotization. Cuticular cross-linking was increased and n decreased with decreased expression of structural proteins, CP10 and CP20. This work establishes n as an important novel parameter for confirming metabolic pathways within load bearing tissues and for understanding structure function relationships within biological polymer composites. Additionally, Tribolium castaneum elytral indentation modulus (800+/-200 MPa) was determined by nanoindentation and a 4nm regular hexagonal pattern on the dorsal side of elytra investigated via scanning, transmission and atomic microscopy. Based on studied biological materials, the combination of rigid macromolecules immersed in a ductile matrix was found to be significant in achieving exceptional mechanical performance. Inspired by this biological design principle, the synthesis, properties and structure of Poly(ethylene glycol) diacrylate/agarose semi-interpenetrating network hydrogels were explored. The resulting novel composite materials were 9x stiffer than agarose and 5x tougher than PEGDA alone and showed good biocompatibility, suggesting promise as a scaffold material for tissue engineering constructs for cartilage regeneration.

  11. Lead free solder mechanics and reliability

    CERN Document Server

    Pang, John Hock Lye

    2012-01-01

    Lead-free solders are used extensively as interconnection materials in electronic assemblies and play a critical role in the global semiconductor packaging and electronics manufacturing industry. Electronic products such as smart phones, notebooks and high performance computers rely on lead-free solder joints to connect IC chip components to printed circuit boards. Lead Free Solder: Mechanics and Reliability provides in-depth design knowledge on lead-free solder elastic-plastic-creep and strain-rate dependent deformation behavior and its application in failure assessment of solder joint reliability. It includes coverage of advanced mechanics of materials theory and experiments, mechanical properties of solder and solder joint specimens, constitutive models for solder deformation behavior; numerical modeling and simulation of solder joint failure subject to thermal cycling, mechanical bending fatigue, vibration fatigue and board-level drop impact tests. This book also: Discusses the mechanical prope...

  12. Biological fractionation of lead isotopes in Sprague-Dawley rats lead poisoned via the respiratory tract.

    Directory of Open Access Journals (Sweden)

    Jing Wu

    Full Text Available It was considered that lead isotope ratios did not change during physical, chemical, or biological processes. Thus, lead isotope ratios have been used as fingerprints to identify possible lead sources. However, recent evidence has shown that the lead isotope ratios among different biological samples in human are not always identical from its lead origins in vitro. An animal experiment was conducted to explore the biological fractionation of lead isotopes in biological systems.24 male Sprague-Dawley (SD rats were divided into groups that received acute lead exposure (0, 0.02, 0.2, or 2 mg/kg body weight of lead acetate via the respiratory route every day for 5 days. Biological samples (i.e., blood, urine, and feces were collected for comparison with the lead acetate (test substance and the low-lead animal feed (diet administered to the rats. The lead isotope ratios were determined by inductively coupled plasma mass spectrometry (ICP-MS.There are significant differences (p<0.05 in lead isotope ratios between blood, urine, and feces. Moreover, a nonlinear relationship between the blood lead concentration and the blood lead isotope ratios was observed. There is also a threshold effect to the fractionation function. Only the blood isotope ratio of (204Pb/(206Pb matches the test substance well. As for feces, when (204Pb/(206Pb ratio is considered, there is no significant difference between feces-test substance pairs in medium and high dose group.The biological fractionation of lead isotopes in SD rats was observed. Moreover, there might be a threshold for the biological fractionation of lead isotopes which is depending on whole blood lead level. It is considered to be more reliable that we compared the isotope ratios of potential lead hazards with both blood and feces lead fingerprints especially for (204Pb/(206Pb ratio under high-dose exposure.

  13. The mechanics of soft biological composites.

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thao D. (Sandia National Laboratories, Livermore, CA); Grazier, John Mark; Boyce, Brad Lee; Jones, Reese E. (Sandia National Laboratories, Livermore, CA)

    2007-10-01

    Biological tissues are uniquely structured materials with technologically appealing properties. Soft tissues such as skin, are constructed from a composite of strong fibrils and fluid-like matrix components. This was the first coordinated experimental/modeling project at Sandia or in the open literature to consider the mechanics of micromechanically-based anisotropy and viscoelasticity of soft biological tissues. We have exploited and applied Sandia's expertise in experimentation and mechanics modeling to better elucidate the behavior of collagen fibril-reinforced soft tissues. The purpose of this project was to provide a detailed understanding of the deformation of ocular tissues, specifically the highly structured skin-like tissue in the cornea. This discovery improved our knowledge of soft/complex materials testing and modeling. It also provided insight into the way that cornea tissue is bio-engineered such that under physiologically-relevant conditions it has a unique set of properties which enhance functionality. These results also provide insight into how non-physiologic loading conditions, such as corrective surgeries, may push the cornea outside of its natural design window, resulting in unexpected non-linear responses. Furthermore, this project created a clearer understanding of the mechanics of soft tissues that could lead to bio-inspired materials, such as highly supple and impact resistant body armor, and improve our design of human-machine interfaces, such as micro-electrical-mechanical (MEMS) based prosthetics.

  14. Biological fractionation of lead isotopes in Sprague-Dawley rats lead poisoned via the respiratory tract.

    Science.gov (United States)

    Wu, Jing; Liu, Duojian; Xie, Qing; Wang, Jingyu

    2012-01-01

    It was considered that lead isotope ratios did not change during physical, chemical, or biological processes. Thus, lead isotope ratios have been used as fingerprints to identify possible lead sources. However, recent evidence has shown that the lead isotope ratios among different biological samples in human are not always identical from its lead origins in vitro. An animal experiment was conducted to explore the biological fractionation of lead isotopes in biological systems. 24 male Sprague-Dawley (SD) rats were divided into groups that received acute lead exposure (0, 0.02, 0.2, or 2 mg/kg body weight of lead acetate) via the respiratory route every day for 5 days. Biological samples (i.e., blood, urine, and feces) were collected for comparison with the lead acetate (test substance) and the low-lead animal feed (diet) administered to the rats. The lead isotope ratios were determined by inductively coupled plasma mass spectrometry (ICP-MS). There are significant differences (pblood, urine, and feces. Moreover, a nonlinear relationship between the blood lead concentration and the blood lead isotope ratios was observed. There is also a threshold effect to the fractionation function. Only the blood isotope ratio of (204)Pb/(206)Pb matches the test substance well. As for feces, when (204)Pb/(206)Pb ratio is considered, there is no significant difference between feces-test substance pairs in medium and high dose group. The biological fractionation of lead isotopes in SD rats was observed. Moreover, there might be a threshold for the biological fractionation of lead isotopes which is depending on whole blood lead level. It is considered to be more reliable that we compared the isotope ratios of potential lead hazards with both blood and feces lead fingerprints especially for (204)Pb/(206)Pb ratio under high-dose exposure.

  15. Mechanism of lead removal by waste materials

    International Nuclear Information System (INIS)

    Qaiser, S.; Saleemi, A.R.; Ahmed, M.M.

    2007-01-01

    Heavy metal ions are priority pollutants, due to their toxicity and mobility in natural water ecosystems. The discharge of heavy metals into aquatic ecosystems has become a matter of concern in Pakistan over the last few decades. These contaminants are introduced into the aquatic systems significantly as a result of various industrial operations. The metals of concern include lead, chromium, zinc, copper, nickel and uranium. Lead is one of the most hazardous and toxic metals. It is used as industrial raw material in the manufacture of storage batteries, pigments, leaded glass, fuels, photographic materials, matches and explosives. Conventional methods for treatment of dissolved lead include precipitation, adsorption, coagulation/notation, sedimentation, reverse osmosis and ion exchange. Each process has its merits and limitations in applications. Adsorption by activated carbon and ion exchange using commercial ion exchange resins are very expensive processes, especially for a developing country like Pakistan. The present research was conducted to identify some waste materials, which can be utilized to remove lead from industrial wastewater. Natural wastes in the form of leaves and ash have considerable amounts of CaO, MgO, Na/sub 2/O, SiO/sub 2/ and Al/sub 2/O/sub 3/ which can be utilized for precipitation and adsorption. Utilization of waste materials to remove lead from industrial wastewater is the basic theme of this research. The waste materials used in this research were maple leaves, pongamia pinata leaves, coal ash and maple ago leave ash. Parameters studied were reaction time, precipitant dose, pH and temperature. It was found that maple leaves ash has maximum lead removal capacity 19.24 mg g/sup -1/ followed by coal ash 13.2 mg g/sup -1/. The optimal pH was 5 for maple leaves and pongamia Pinata leaves; and 4 for coal ash and maple leaves ash. Removal capacity decreased with increase in temperature. The major removal mechanisms were adsorption and

  16. Biosorption of lead phosphates by lead-tolerant bacteria as a mechanism for lead immobilization.

    Science.gov (United States)

    Rodríguez-Sánchez, Viridiana; Guzmán-Moreno, Jesús; Rodríguez-González, Vicente; Flores-de la Torre, Juan Armando; Ramírez-Santoyo, Rosa María; Vidales-Rodríguez, Luz Elena

    2017-08-01

    The study of metal-tolerant bacteria is important for bioremediation of contaminated environments and development of green technologies for material synthesis due to their potential to transform toxic metal ions into less toxic compounds by mechanisms such as reduction, oxidation and/or sequestration. In this study, we report the isolation of seven lead-tolerant bacteria from a metal-contaminated site at Zacatecas, México. The bacteria were identified as members of the Staphylococcus and Bacillus genera by microscopic, biochemical and 16S rDNA analyses. Minimal inhibitory concentration of these isolates was established between 4.5 and 7.0 mM of Pb(NO 3 ) 2 in solid and 1.0-4.0 mM of Pb(NO 3 ) 2 in liquid media. A quantitative analysis of the lead associated to bacterial biomass in growing cultures, revealed that the percentage of lead associated to biomass was between 1 and 37% in the PbT isolates. A mechanism of complexation/biosorption of lead ions as inorganic phosphates (lead hydroxyapatite and pyromorphite) in bacterial biomass, was determined by Fourier transform infrared spectroscopy and X-ray diffraction analyses. Thus, the ability of the lead-tolerant isolates to transform lead ions into stable and highly insoluble lead minerals make them potentially useful for immobilization of lead in mining waste.

  17. Fracture mechanisms in lead zirconate titanate ceramics

    International Nuclear Information System (INIS)

    Freiman, S.W.; Chuck, L.; Mecholsky, J.J.; Shelleman, D.L.

    1986-01-01

    Lead Zirconate Titanate (PZT) ceramics can be formed over a wide range of PbTiO 3 /PbZrO 3 ratios and exist in a number of crystal structures. This study involved the use of various fracture mechanics techniques to determine critical fracture toughness, K /SUB IC/ , as a function of composition, microstructure, temperature, and electrical and thermal history. The results of these experiments indicate that variations in K /SUB IC/ are related to phase transformations in the material as well as to other toughening mechanisms such as twinning and microcracking. In addition, the strength and fracture toughness of selected PZT ceramics were determined using specimens in which a crack was introduced by a Vicker's hardness indentor. The variation of K /SUB IC/ with composition and microstructure was related to the extent of twin-crack interaction. Comparison of the plot of strength as a function of indentation load with that predicted from indentation fracture models indicates the presence of internal stresses which contribute to failure. The magnitude of these internal stresses has been correlated with electrical properties of the ceramic. Fractographic analysis was used to determine the magnitude of internal stresses in specimens failing from ''natural flaws.''

  18. Biology and Mechanics of Blood Flows Part I: Biology

    CERN Document Server

    Thiriet, Marc

    2008-01-01

    Biology and Mechanics of Blood Flows presents the basic knowledge and state-of-the-art techniques necessary to carry out investigations of the cardiovascular system using modeling and simulation. Part I of this two-volume sequence, Biology, addresses the nanoscopic and microscopic scales. The nanoscale corresponds to the scale of biochemical reaction cascades involved in cell adaptation to mechanical stresses among other stimuli. The microscale is the scale of stress-induced tissue remodeling associated with acute or chronic loadings. The cardiovascular system, like any physiological system, has a complicated three-dimensional structure and composition. Its time dependent behavior is regulated, and this complex system has many components. In this authoritative work, the author provides a survey of relevant cell components and processes, with detailed coverage of the electrical and mechanical behaviors of vascular cells, tissues, and organs. Because the behaviors of vascular cells and tissues are tightly coupl...

  19. Physical mechanisms of biological molecular motors

    Energy Technology Data Exchange (ETDEWEB)

    Miller, John H. Jr. [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Ste. 617 SR1 Houston, TX 77204-5005 (United States)], E-mail: jhmiller@uh.edu; Vajrala, Vijayanand; Infante, Hans L. [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Ste. 617 SR1 Houston, TX 77204-5005 (United States); Claycomb, James R. [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Ste. 617 SR1 Houston, TX 77204-5005 (United States); Department of Mathematics and Physics, Houston Baptist University, 7502 Fondren Road, Houston, TX 77074-3298 (United States); Palanisami, Akilan; Fang Jie; Mercier, George T. [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Ste. 617 SR1 Houston, TX 77204-5005 (United States)

    2009-03-01

    Biological motors generally fall into two categories: (1) those that convert chemical into mechanical energy via hydrolysis of a nucleoside triphosphate, usually adenosine triphosphate, regarded as life's chemical currency of energy and (2) membrane bound motors driven directly by an ion gradient and/or membrane potential. Here we argue that electrostatic interactions play a vital role for both types of motors and, therefore, the tools of physics can greatly contribute to understanding biological motors.

  20. Physical mechanisms of biological molecular motors

    International Nuclear Information System (INIS)

    Miller, John H. Jr.; Vajrala, Vijayanand; Infante, Hans L.; Claycomb, James R.; Palanisami, Akilan; Fang Jie; Mercier, George T.

    2009-01-01

    Biological motors generally fall into two categories: (1) those that convert chemical into mechanical energy via hydrolysis of a nucleoside triphosphate, usually adenosine triphosphate, regarded as life's chemical currency of energy and (2) membrane bound motors driven directly by an ion gradient and/or membrane potential. Here we argue that electrostatic interactions play a vital role for both types of motors and, therefore, the tools of physics can greatly contribute to understanding biological motors

  1. The mathematics and mechanics of biological growth

    CERN Document Server

    Goriely, Alain

    2017-01-01

    This monograph presents a general mechanical theory for biological growth. It provides both a conceptual and a technical foundation for the understanding and analysis of problems arising in biology and physiology. The theory and methods is illustrated on a wide range of examples and applications. A process of extreme complexity, growth plays a fundamental role in many biological processes and is considered to be the hallmark of life itself. Its description has been one of the fundamental problems of life sciences, but until recently, it has not attracted much attention from mathematicians, physicists, and engineers. The author herein presents the first major technical monograph on the problem of growth since D’Arcy Wentworth Thompson’s 1917 book On Growth and Form. The emphasis of the book is on the proper mathematical formulation of growth kinematics and mechanics. Accordingly, the discussion proceeds in order of complexity and the book is divided into five parts. First, a general introduction on the pro...

  2. Biological mechanisms, one molecule at a time

    Science.gov (United States)

    Tinoco, Ignacio; Gonzalez, Ruben L.

    2011-01-01

    The last 15 years have witnessed the development of tools that allow the observation and manipulation of single molecules. The rapidly expanding application of these technologies for investigating biological systems of ever-increasing complexity is revolutionizing our ability to probe the mechanisms of biological reactions. Here, we compare the mechanistic information available from single-molecule experiments with the information typically obtained from ensemble studies and show how these two experimental approaches interface with each other. We next present a basic overview of the toolkit for observing and manipulating biology one molecule at a time. We close by presenting a case study demonstrating the impact that single-molecule approaches have had on our understanding of one of life's most fundamental biochemical reactions: the translation of a messenger RNA into its encoded protein by the ribosome. PMID:21685361

  3. Microchannel boiling mechanisms leading to burnout

    International Nuclear Information System (INIS)

    Landram, C.S.; Riddle, R.A.

    1994-01-01

    The authors are analyzing the thermal performance of microchannel heat sinks to extend their applied heat loads beyond coolant single-phase limits. This is the first investigation of boiling in the narrow (50-μm) microchannels having typically high-aspect-ratio (of order 10/1) flow cross-sections. The prescription of local, wall-coolant, interfacial, two-phase correlations first required development of a validated, approximate, thermal-model accounting for conjugate heat transfer. The strongest mechanism for heat transfer in two-phase microchannel flow was found to be saturated boiling in a channel region near the heated base. When this region dried out, burnout occurred, both in the computations and in the experiment

  4. Biological Applications of Hybrid Quantum Mechanics/Molecular Mechanics Calculation

    Directory of Open Access Journals (Sweden)

    Jiyoung Kang

    2012-01-01

    Full Text Available Since in most cases biological macromolecular systems including solvent water molecules are remarkably large, the computational costs of performing ab initio calculations for the entire structures are prohibitive. Accordingly, QM calculations that are jointed with MM calculations are crucial to evaluate the long-range electrostatic interactions, which significantly affect the electronic structures of biological macromolecules. A UNIX-shell-based interface program connecting the quantum mechanics (QMs and molecular mechanics (MMs calculation engines, GAMESS and AMBER, was developed in our lab. The system was applied to a metalloenzyme, azurin, and PU.1-DNA complex; thereby, the significance of the environmental effects on the electronic structures of the site of interest was elucidated. Subsequently, hybrid QM/MM molecular dynamics (MD simulation using the calculation system was employed for investigation of mechanisms of hydrolysis (editing reaction in leucyl-tRNA synthetase complexed with the misaminoacylated tRNALeu, and a novel mechanism of the enzymatic reaction was revealed. Thus, our interface program can play a critical role as a powerful tool for state-of-the-art sophisticated hybrid ab initio QM/MM MD simulations of large systems, such as biological macromolecules.

  5. Mechanically driven interface propagation in biological tissues

    International Nuclear Information System (INIS)

    Ranft, Jonas; Joanny, Jean-François; Aliee, Maryam; Jülicher, Frank; Prost, Jacques

    2014-01-01

    Many biological tissues consist of more than one cell type. We study the dynamics of an interface between two different cell populations as it occurs during the growth of a tumor in a healthy host tissue. Recent work suggests that the rates of cell division and cell death are under mechanical control, characterized by a homeostatic pressure. The difference in the homeostatic pressures of two cell types drives the propagation of the interface, corresponding to the invasion of one cell type into the other. We derive a front propagation equation that takes into account the coupling between cell number balance and tissue mechanics. We show that in addition to pulled fronts, pushed-front solutions occur as a result of convection driven by mechanics. (paper)

  6. Quantum mechanics formalism for biological evolution

    International Nuclear Information System (INIS)

    Bianconi, Ginestra; Rahmede, Christoph

    2012-01-01

    Highlights: ► Biological evolution is an off-equilibrium process described by path integrals over phylogenies. ► The phylogenies are sums of linear lineages for asexual populations. ► For sexual populations, each lineage is a tree and the path integral is given by a sum over these trees. ► Quantum statistics describe the stationary state of biological populations in simple cases. - Abstract: We study the evolution of sexual and asexual populations in fitness landscapes compatible with epistatic interactions. We find intriguing relations between the mathematics of biological evolution and quantum mechanics formalism. We give the general structure of the evolution of sexual and asexual populations which is in general an off-equilibrium process that can be expressed by path integrals over phylogenies. These phylogenies are the sum of linear lineages for asexual populations. For sexual populations, instead, each lineage is a tree of branching ratio two and the path integral describing the evolving population is given by a sum over these trees. Finally we show that the Bose–Einstein and the Fermi–Dirac distributions describe the stationary state of biological populations in simple cases.

  7. [Molecular Biology on the Mechanisms of Autism Spectrum Disorder for Clinical Psychiatrists].

    Science.gov (United States)

    Makinodan, Manabu

    2015-01-01

    While, in general, a certain number of clinical psychiatrists might not be familiar with molecular biology, the mechanisms of mental illnesses have been uncovered by molecular biology for decades. Among mental illnesses, even biological psychiatrists and neuroscientists have paid less attention to the biological treatment of autism spectrum disorder (ASD) than Alzheimer's disease and schizophrenia since ASD has been regarded as a developmental disorder that was seemingly untreatable. However, multifaceted methods of molecular biology have revealed the mechanisms that would lead to the medication of ASD. In this article, how molecular biology dissects the pathobiology of ASD is described in order to announce the possibilities of biological treatment for clinical psychiatrists.

  8. The Cytoskeleton: Mechanical, Physical, and Biological Interactions

    Science.gov (United States)

    1996-01-01

    This workshop, entitled "The Cytoskeleton: Mechanical, Physical, and Biological Interactions," was sponsored by the Center for Advanced Studies in the Space Life Sciences at the Marine Biological Laboratory. This Center was established through a cooperative agreement between the MBL and the Life Sciences Division of the National Aeronautics and Space Administration. To achieve these goals, the Center sponsors a series of workshops on various topics in the life sciences. Elements of the cytoskeleton have been implicated in the effects of gravity on the growth of plants fungi. An intriguing finding in this regard is the report indicating that an integrin-like protein may be the gravireceptor in the internodal cells of Chara. Involvement of the cytoskeleton in cellular graviperception of the basidiomycete Flammulina velutipes has also been reported. Although the responses of mammalian cells to gravity are not well documented, it has been proposed that integrins can act as mechanochemical transducers in mammalian cells. Little is known about the integrated mechanical and physical properties of cytoplasm, this workshop would be the best place to begin developing interdisciplinary approaches to the effects of mechanical stresses on cells and their most likely responsive cytoplasmic elements- the fibrous proteins comprising the cytoskeleton.

  9. Toward mechanical systems biology in bone.

    Science.gov (United States)

    Trüssel, Andreas; Müller, Ralph; Webster, Duncan

    2012-11-01

    Cyclic mechanical loading is perhaps the most important physiological factor regulating bone mass and shape in a way which balances optimal strength with minimal weight. This bone adaptation process spans multiple length and time scales. Forces resulting from physiological exercise at the organ scale are sensed at the cellular scale by osteocytes, which reside inside the bone matrix. Via biochemical pathways, osteocytes orchestrate the local remodeling action of osteoblasts (bone formation) and osteoclasts (bone resorption). Together these local adaptive remodeling activities sum up to strengthen bone globally at the organ scale. To resolve the underlying mechanisms it is required to identify and quantify both cause and effect across the different scales. Progress has been made at the different scales experimentally. Computational models of bone adaptation have been developed to piece together various experimental observations at the different scales into coherent and plausible mechanisms. However additional quantitative experimental validation is still required to build upon the insights which have already been achieved. In this review we discuss emerging as well as state of the art experimental and computational techniques and how they might be used in a mechanical systems biology approach to further our understanding of the mechanisms governing load induced bone adaptation, i.e., ways are outlined in which experimental and computational approaches could be coupled, in a quantitative manner to create more reliable multiscale models of bone.

  10. Xenon preconditioning: molecular mechanisms and biological effects

    Directory of Open Access Journals (Sweden)

    Liu Wenwu

    2013-01-01

    Full Text Available Abstract Xenon is one of noble gases and has been recognized as an anesthetic for more than 50 years. Xenon possesses many of the characteristics of an ideal anesthetic, but it is not widely applied in clinical practice mainly because of its high cost. In recent years, numerous studies have demonstrated that xenon as an anesthetic can exert neuroprotective and cardioprotective effects in different models. Moreover, xenon has been applied in the preconditioning, and the neuroprotective and cardioprotective effects of xenon preconditioning have been investigated in a lot of studies in which some mechanisms related to these protections are proposed. In this review, we summarized these mechanisms and the biological effects of xenon preconditioning.

  11. Synthetic biology: a challenge to mechanical explanations in biology?

    Science.gov (United States)

    Morange, Michel

    2012-01-01

    In their plans to modify organisms, synthetic biologists have contrasted engineering and tinkering. By drawing this contrast between their endeavors and what has happened during the evolution of organisms by natural selection, they underline the novelty of their projects and justify their ambitions. Synthetic biologists are at odds with a long tradition that has considered organisms as "perfect machines." This tradition had already been questioned by Stephen Jay Gould in the 1970s and received a major blow with the comparison made by François Jacob between organisms and the results of "bricolage" (tinkering). These contrasts between engineering and tinkering, synthetic biology and evolution, have no raison d'être. Machines built by humans are increasingly inspired by observations made on organisms. This is not a simple reversal of the previous trend-the mechanical conception of organisms-in which the characteristics of the latter were explained by comparison with human-built machines. Relations between organisms and machines have always been complex and ambiguous.

  12. Mechanical properties of nanostructure of biological materials

    Science.gov (United States)

    Ji, Baohua; Gao, Huajian

    2004-09-01

    Natural biological materials such as bone, teeth and nacre are nanocomposites of protein and mineral with superior strength. It is quite a marvel that nature produces hard and tough materials out of protein as soft as human skin and mineral as brittle as classroom chalk. What are the secrets of nature? Can we learn from this to produce bio-inspired materials in the laboratory? These questions have motivated us to investigate the mechanics of protein-mineral nanocomposite structure. Large aspect ratios and a staggered alignment of mineral platelets are found to be the key factors contributing to the large stiffness of biomaterials. A tension-shear chain (TSC) model of biological nanostructure reveals that the strength of biomaterials hinges upon optimizing the tensile strength of the mineral crystals. As the size of the mineral crystals is reduced to nanoscale, they become insensitive to flaws with strength approaching the theoretical strength of atomic bonds. The optimized tensile strength of mineral crystals thus allows a large amount of fracture energy to be dissipated in protein via shear deformation and consequently enhances the fracture toughness of biocomposites. We derive viscoelastic properties of the protein-mineral nanostructure and show that the toughness of biocomposite can be further enhanced by the viscoelastic properties of protein.

  13. Biological mechanisms of gallium-67 tumor deposition

    International Nuclear Information System (INIS)

    Okuyama, Shinichi; Takeda, Shumpei; Sato, Tachio; Takusagawa, Kimihiko; Awano, Takayuki.

    1979-01-01

    This investigation was undertaken in order to clarify the tumor deposition mechanisms of 67 Ga citrate, a ''universal tumor labeler''. An interspecies comparison of various tumors in the rat and mouse indicated that its highest deposition was in the undifferentiated cell type. Amongst the siblings of experimental tumors, cellular membrane negative charge is greater in the free-cell types than the island-formers: a short-term labeling study revealed a greater 67 Ga deposition in the free-cell types. A subcellar fractionation showed an initial association of 67 Ga with the nuclear and membrane fractions, and a later transition to the lysosomal. Hypotonic lysis revealed a paralleled release of 67 Ga and lysosomal key enzymes. Morphological abnormality of the cancer lysosomes was thought to agree with their Ga retention. This property was clinically confirmed by a scintiscoring technique. Treatment with cold gallium of tumors modified the biological parameters of tumor growth: in vitro it suppressed cell proliferation, reduced saturation density; and produced cellular pleomorphism. In vivo it increased tumor consistency by reducing central necrosis and increasing the viable cell layer thickness. Thus, 67 Ga deposition is closely related to various biological parameters of malignancy including the cellular membrane negative charge as cancer is a membrane disorder, and the lysosomal morphology and function. (author)

  14. Neurotrophin Propeptides: Biological Functions and Molecular Mechanisms.

    Science.gov (United States)

    Rafieva, Lola M; Gasanov, Eugene V

    2016-01-01

    Neurotrophins constitute a family of growth factors that play a key role in the regulation of the development and function of the central and peripheral nervous systems. A common feature of all the neurotrophins is their synthesis in cells as long precursors (pre-pro-neurotrophins) that contain an N-terminal signal peptide, a following propeptide and the mature neurotrophin. Although the signal peptide functions have been well studied, the role of neurotrophin propeptides is not so clear. Here, we briefly summarize the biochemistry of neurotrophin propeptides, including their role as folding-assistants for the mature factor and their role in processing and in secretion of neurotrophins. In the main part of the review we summarize our current state of knowledge of the biological activity of neurotrophin propeptides, their possible mechanisms of action, and their potential influence on the activity of the mature neurotrophins.

  15. Biological Mechanism of Silver Nanoparticle Toxicity

    Science.gov (United States)

    Armstrong, Najealicka Nicole

    Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities above that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, these investigations were attempted to monitor the effects of AgNPs at a non-lethal concentration on wild type Drosophila melanogaster by exposing them to nanoparticles throughout their development. All adult flies raised in AgNP doped food indicated that of not more than 50 mg/L had no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised after AgNP feeding. The determination of the amount of free ionic silver (Ag+) indicated that the observed biological effects had resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, were decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Furthermore, copper supplementation restored the loss of AgNP induced demelanization, and the reduction of functional Ctr1 in Ctr1 heterozygous mutants caused the flies to be resistant to demelanization. Consequently, these studies proposed a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explained the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, these investigations demonstrated that Drosophila, an established genetic model system, can be well utilized for further

  16. Direct landfill disposal versus Mechanical Biological Treatment (MBT

    Directory of Open Access Journals (Sweden)

    Kulhawik Katarzyna

    2016-09-01

    Full Text Available After the implementation of a new waste management system, in which recycling is the most dominating process, landfill disposal still appears to be the most popular method of waste management in Poland, in which waste undergoes gradual decomposition and the influence of climate conditions, for example, air and atmospheric fallout, leads to the production of leachate and biogas emissions, which contribute to continual threats to the natural environment and humans. The above-mentioned threats can be limited by applying suitable techniques of waste treatment before its disposal. A technology that is oriented to these aims is a mechanical biological treatment (MBT before disposal.

  17. Discriminative topological features reveal biological network mechanisms

    Directory of Open Access Journals (Sweden)

    Levovitz Chaya

    2004-11-01

    Full Text Available Abstract Background Recent genomic and bioinformatic advances have motivated the development of numerous network models intending to describe graphs of biological, technological, and sociological origin. In most cases the success of a model has been evaluated by how well it reproduces a few key features of the real-world data, such as degree distributions, mean geodesic lengths, and clustering coefficients. Often pairs of models can reproduce these features with indistinguishable fidelity despite being generated by vastly different mechanisms. In such cases, these few target features are insufficient to distinguish which of the different models best describes real world networks of interest; moreover, it is not clear a priori that any of the presently-existing algorithms for network generation offers a predictive description of the networks inspiring them. Results We present a method to assess systematically which of a set of proposed network generation algorithms gives the most accurate description of a given biological network. To derive discriminative classifiers, we construct a mapping from the set of all graphs to a high-dimensional (in principle infinite-dimensional "word space". This map defines an input space for classification schemes which allow us to state unambiguously which models are most descriptive of a given network of interest. Our training sets include networks generated from 17 models either drawn from the literature or introduced in this work. We show that different duplication-mutation schemes best describe the E. coli genetic network, the S. cerevisiae protein interaction network, and the C. elegans neuronal network, out of a set of network models including a linear preferential attachment model and a small-world model. Conclusions Our method is a first step towards systematizing network models and assessing their predictability, and we anticipate its usefulness for a number of communities.

  18. Mechanical properties of JPDR biological shield concrete

    International Nuclear Information System (INIS)

    Idei, Yoshio; Kamata, Hiroshi; Akutsu, Youichi; Onizawa, Kunio; Nakajima, Nobuya; Sukegawa, Takenori; Kakizaki, Masayoshi.

    1990-11-01

    Plant life of nuclear power plant will be determined by the aging degradation of main components and structures because of the difficulty and the cost of the replacement. These components are the reactor pressure vessel, concrete structures and cables. Authors have performed the investigation of JPDR biological shield which was the succeeded in first generating electricity in Japan and is now being decommissioned in JAERI. The test core samples were bored from the shield concrete and tested to obtain the mechanical properties. Test results are summarized as below, (1) Peak value of fast neutron dose was estimated as 1 x 10 18 n/cm 2 which is equivalent to the dose at the end of life for commercial power reactor. (2) Averaged compressive strength of all specimens had been increased about 20 % compared with initial design strength. (3) It was identified that the compressive strength had a little trend to increase with the increase of neutron dose within the dose range obtained in this study. (4) Tensile strength, Elastic modulus and Poisson's ratio showed little effect of neutron dose. (5) It was suggested that the inside and the mid-section liners were effective to keep the water in concrete and to avoid the reduction in strength. (author)

  19. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators

    International Nuclear Information System (INIS)

    Schmitz, Andreas

    2013-01-01

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb 1-x Ca x Te were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while its thermoelectric properties

  20. Obstructive renal injury: from fluid mechanics to molecular cell biology.

    Science.gov (United States)

    Ucero, Alvaro C; Gonçalves, Sara; Benito-Martin, Alberto; Santamaría, Beatriz; Ramos, Adrian M; Berzal, Sergio; Ruiz-Ortega, Marta; Egido, Jesus; Ortiz, Alberto

    2010-04-22

    Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making.

  1. Evaluation of lead in biological samples treated with radiation

    International Nuclear Information System (INIS)

    Gomaa, O.M.

    1996-01-01

    The active dry yeast saccharomyces cerevisiae was able to remove lead successfully from the media. The yeast cells (5 g/100 ml) tolerated up to 8190 ppm lead. The most appropriate conditions for better uptake was when the yeast cells were incubated for 2 hours with different concentrations of lead. Both live and dead cells showed an uptake that exceeded 80% even when there was only 16% of the cells alive. The X RF technique proved that lead is associated with the cells, little, or no lead is found in the media after incubation. Lead bio sorption was investigated in concentrations ranging from 500 to 8000 ppm, the uptake followed the Langmuir and Freundlich adsorption models and was found to be 180 mg/g when the incubation was for 2 h rs. Increasing the concentration of peptone from 0 to 1.5% induced a significant increase in metal removal. Incubating the metal with the cells at 45% showed an uptake that reached 97.44%. Radiation affected the metal uptake to a great extent, increasing the dose of exposure to the cells incubated with lead. led to the increase in the uptake of the metal. When the dose of exposure was 8 kGy, the metal removal reached a maximum of 91% compared to 84 for non-irradiated samples. When the irradiated cells were incubated with lead a variable uptake capacity was observed. When the cells were exposed to 4 kGy, they were capable of removing the metal more efficiently, other exposure doses showed an uptake that was almost the same. Transmission electron microscopy revealed that lead was deposited as electron dense granules around the cells. The EDX identified the metal. The scanning electron microscopy showed that the morphology of the cells was affected when radiation was used, the cells shrunk and lost their ellipsoidal shape, while the addition of lead did not affect their morphology at all

  2. Effects of lead on the killing mechanisms of polymorphonuclear leukocytes

    International Nuclear Information System (INIS)

    Silberstein, C.F.

    1984-01-01

    The effects of lead on the killing mechanisms of rat polymorphonuclear leukocytes (PMN) were investigated, using male Long-Evans rats exposed to 1% lead acetate in the drinking water for varying periods of time to achieve blood lead levels ranging from 20-200 μg/dl. Studies of PMN bacterial and fungal killing activity, chemotaxis and phagocytosis demonstrated that: 1) bactericidal activity of PMN from rats exposed to lead was not altered; 2) chemotactic activity remained within normal limits; 3) the phagocytic ability of the PMN also remained unaltered. In addition to these normal findings, one major abnormality was demonstrated: a significant decrease in the ability of PMN from rats exposed to lead to kill Candida albicans. This defect was not related to age or to length of exposure. It could not be produced by addition of lead to the test system in vitro. Further investigation revealed significant decreases in PMN glucose-6-phosphate dehydrogenase, catalase, and myeloperoxidase activities. These data support two possible mechanisms for the abnormal fungicidal activity of PMN from lead-exposed rats: decrease in ability to reduce oxygen to active metabolites, or reduction in myeloperoxidase activity due to diminshed synthesis of the heme moiety required for its function

  3. Biology: An Important Agricultural Engineering Mechanism

    Science.gov (United States)

    Henderson, S. M.

    1974-01-01

    Describes the field of bioengineering with particular emphasis on agricultural engineering, and presents the results of a survey of schools that combine biology and engineering in their curricula. (JR)

  4. Determination of lead and cadmium in biological materials

    International Nuclear Information System (INIS)

    Stoeppler, M.; Backhaus, F.; Dahl, R.; Hagedorn-Goetz, H.; Hilpert, K.; Klahre, P.; Rutzel, H.; Valenta, P.; Nuernberg, H.W.; Dumont, M.

    1975-01-01

    Sampling techniques and experience, and decomposition methods are presented. The processes used in flameless atomic absorption spectrometry (including the method using automatic insertion of samples), pulse polarography and isotope dilution mass spectrometry are described. Finally, the results of lead and cadmium measurements in bovine liver, blood, urine and hair samples are reported and discussed with a comparison of methods in some cases

  5. Female juvenile murderers: Biological and psychological dynamics leading to homicide.

    Science.gov (United States)

    Heide, Kathleen M; Solomon, Eldra P

    2009-01-01

    The increasing involvement of girls under 18 in violent crime has been a matter of growing concern in the United States in recent years. This article reviews the arrests of female juveniles for violent crime and then focuses specifically on their involvement in homicide. Arrests of girls for murder, unlike arrests for assault, have not risen over the last 30 years, suggesting that the dynamics that propel female juveniles to engage in lethal violence differ from those contributing to assaultive behavior by this same group. A review of the literature indicates that theories as to why female adolescents kill do not take into account recent scientific findings on brain development and the biological effects of early trauma in explaining serious violent behavior by girls. Three cases, evaluated by the authors, involving female adolescents charged with murder or attempted murder, are presented. The authors focus on the biological and psychological dynamics that help explain their violent behavior. They discuss the effects of insecure attachment and child maltreatment, and trace a critical pathway between these early experiences and future risk of violent behavior. The dynamics of child maltreatment in fostering rage and violence are discussed thereafter in terms of offender accountability. The article concludes with a discussion of treatment and recommendations for future research.

  6. Mechanics of Biological Tissues and Biomaterials : Current Trends (editorial)

    NARCIS (Netherlands)

    Zadpoor, A.A.

    2015-01-01

    Investigation of the mechanical behavior of biological tissues and biomaterials has been an active area of research for several decades. However, in recent years, the enthusiasm in understanding the mechanical behavior of biological tissues and biomaterials has increased significantly due to the

  7. Molecular biological mechanisms I. DNA repair

    International Nuclear Information System (INIS)

    Friedl, A.A.

    2000-01-01

    Cells of all living systems possess a variety of mechanisms that allow to repair spontaneous and exogeneously induced DNA damage. DNA repair deficiencies may invoke enhanced sensitivity towards DNA-damaging agents such as ionizing radiation. They may also enhance the risk of cancer development, both spontaneously or after induction. This article reviews several DNA repair mechanisms, especially those dealing with DNA double-strand breaks, and describes hereditary diseases associated with DNA repair defects. (orig.) [de

  8. Biophysical mechanisms complementing "classical" cell biology.

    Science.gov (United States)

    Funk, Richard H W

    2018-01-01

    This overview addresses phenomena in cell- and molecular biology which are puzzling by their fast and highly coordinated way of organization. Generally, it appears that informative processes probably involved are more on the biophysical than on the classical biochemical side. The coordination problem is explained within the first part of the review by the topic of endogenous electrical phenomena. These are found e.g. in fast tissue organization and reorganization processes like development, wound healing and regeneration. Here, coupling into classical biochemical signaling and reactions can be shown by modern microscopy, electronics and bioinformatics. Further, one can follow the triggered reactions seamlessly via molecular biology till into genetics. Direct observation of intracellular electric processes is very difficult because of e.g. shielding through the cell membrane and damping by other structures. Therefore, we have to rely on photonic and photon - phonon coupling phenomena like molecular vibrations, which are addressed within the second part. Molecules normally possess different charge moieties and thus small electromagnetic (EMF) patterns arise during molecular vibration. These patterns can now be measured best within the optical part of the spectrum - much less in the lower terahertz till kHz and lower Hz part (third part of this review). Finally, EMFs facilitate quantum informative processes in coherent domains of molecular, charge and electron spin motion. This helps to coordinate such manifold and intertwined processes going on within cells, tissues and organs (part 4). Because the phenomena described in part 3 and 4 of the review still await really hard proofs we need concerted efforts and a combination of biophysics, molecular biology and informatics to unravel the described mysteries in "physics of life".

  9. Universal biology and the statistical mechanics of early life

    Science.gov (United States)

    Goldenfeld, Nigel; Biancalani, Tommaso; Jafarpour, Farshid

    2017-11-01

    All known life on the Earth exhibits at least two non-trivial common features: the canonical genetic code and biological homochirality, both of which emerged prior to the Last Universal Common Ancestor state. This article describes recent efforts to provide a narrative of this epoch using tools from statistical mechanics. During the emergence of self-replicating life far from equilibrium in a period of chemical evolution, minimal models of autocatalysis show that homochirality would have necessarily co-evolved along with the efficiency of early-life self-replicators. Dynamical system models of the evolution of the genetic code must explain its universality and its highly refined error-minimization properties. These have both been accounted for in a scenario where life arose from a collective, networked phase where there was no notion of species and perhaps even individuality itself. We show how this phase ultimately terminated during an event sometimes known as the Darwinian transition, leading to the present epoch of tree-like vertical descent of organismal lineages. These examples illustrate concrete examples of universal biology: the quest for a fundamental understanding of the basic properties of living systems, independent of precise instantiation in chemistry or other media. This article is part of the themed issue 'Reconceptualizing the origins of life'.

  10. Dissecting the Molecular Mechanisms of Neurodegenerative Diseases through Network Biology

    Directory of Open Access Journals (Sweden)

    Jose A. Santiago

    2017-05-01

    Full Text Available Neurodegenerative diseases are rarely caused by a mutation in a single gene but rather influenced by a combination of genetic, epigenetic and environmental factors. Emerging high-throughput technologies such as RNA sequencing have been instrumental in deciphering the molecular landscape of neurodegenerative diseases, however, the interpretation of such large amounts of data remains a challenge. Network biology has become a powerful platform to integrate multiple omics data to comprehensively explore the molecular networks in the context of health and disease. In this review article, we highlight recent advances in network biology approaches with an emphasis in brain-networks that have provided insights into the molecular mechanisms leading to the most prevalent neurodegenerative diseases including Alzheimer’s (AD, Parkinson’s (PD and Huntington’s diseases (HD. We discuss how integrative approaches using multi-omics data from different tissues have been valuable for identifying biomarkers and therapeutic targets. In addition, we discuss the challenges the field of network medicine faces toward the translation of network-based findings into clinically actionable tools for personalized medicine applications.

  11. Biological index of environmental lead pollution: accumulation of lead in liver and kidney in mice.

    Science.gov (United States)

    Takano, T; Okutomi, Y; Mochizuki, M; Ochiai, Y; Yamada, F; Mori, M; Ueda, F

    2015-12-01

    Lead (Pb) is known to be highly poisonous, and the acute poisoning of Cd causes the abdominal pains, vomiting, and shock. The digestive and nervous symptom is observed in the chronic lead poisoning. It was also known that the defect in hemoglobin synthesis by Pb produce anemia. The release of Pb into the environment presents a source of exposure for wild animals. In this study, we examined the utility of a new Pb-monitoring index in mice administered Pb. A solution containing 0.02, 0.2, 2, or 4 ppm lead chloride (PbCl2) was administered intraperitoneally to mice, and the Pb contents of the kidney and liver were determined at designated time points. The mean Pb content of both organs increased depending on the administered Pb dosage. Although the results of control was near the detection limits, the administration of 4 ppm in 4 weeks resulted in Pb levels of 260 mg ppm/wet weight and 110 ppm wet weight in the kidney and liver, respectively. However, there were no significant relationships among administered dose, duration of Pb treatment, and liver or kidney Pb content. Then, values in all mice administered control or 0.02 mg Pb were located inside the ellipse, representing the confidence area of the new index, and values in all mice administered more than 2 mg Pb were located outside the ellipse. These results confirm that animals exposed to high concentrations of Pb would be detected by this new index.

  12. The biological significance of brain barrier mechanisms

    DEFF Research Database (Denmark)

    Saunders, Norman R; Habgood, Mark D; Møllgård, Kjeld

    2016-01-01

    , but more work is required to evaluate the method before it can be tried in patients. Overall, our view is that much more fundamental knowledge of barrier mechanisms and development of new experimental methods will be required before drug targeting to the brain is likely to be a successful endeavor......Barrier mechanisms in the brain are important for its normal functioning and development. Stability of the brain's internal environment, particularly with respect to its ionic composition, is a prerequisite for the fundamental basis of its function, namely transmission of nerve impulses....... In addition, the appropriate and controlled supply of a wide range of nutrients such as glucose, amino acids, monocarboxylates, and vitamins is also essential for normal development and function. These are all cellular functions across the interfaces that separate the brain from the rest of the internal...

  13. Immunomodulatory Effects of Macrolide Antibiotics - Part 1 : Biological Mechanisms

    NARCIS (Netherlands)

    Altenburg, J.; de Graaff, C. S.; van der Werf, T. S.; Boersma, W. G.

    2011-01-01

    Macrolide antibiotics are well known for their antibacterial and anti-inflammatory properties. This article provides an overview of the biological mechanisms through which macrolides exert this 'double effect'. Their antibacterial effect consists of the inhibition of bacterial protein synthesis,

  14. Mechanics of Biological Tissues and Biomaterials: Current Trends

    OpenAIRE

    Amir A. Zadpoor

    2015-01-01

    Investigation of the mechanical behavior of biological tissues and biomaterials has been an active area of research for several decades. However, in recent years, the enthusiasm in understanding the mechanical behavior of biological tissues and biomaterials has increased significantly due to the development of novel biomaterials for new fields of application, along with the emergence of advanced computational techniques. The current Special Issue is a collection of studies that address variou...

  15. Mechanics of Biological Tissues and Biomaterials: Current Trends (editorial)

    OpenAIRE

    Zadpoor, A.A.

    2015-01-01

    Investigation of the mechanical behavior of biological tissues and biomaterials has been an active area of research for several decades. However, in recent years, the enthusiasm in understanding the mechanical behavior of biological tissues and biomaterials has increased significantly due to the development of novel biomaterials for new fields of application, along with the emergence of advanced computational techniques. The current Special Issue is a collection of studies that address variou...

  16. Low dose irradiation and biological defense mechanisms

    International Nuclear Information System (INIS)

    Sugahara, Tsutomu; Sagan, L.A.; Aoyama, Takashi

    1992-01-01

    It has been generally accepted in the context of radiation protection that ionizing radiation has some adverse effect even at low doses. However, epidemiological studies of human populations cannot definitively show its existence or absence. Furthermore, recent studies of populations living in areas of different background radiation levels reported some decrease in adverse health effects at high background levels. Genetic studies of atomic bomb survivors failed to produce statistically significant findings on the mutagenic effects of ionizing radiation. A British study however, suggests that a father's exposure to low dose radiation on the job may increase his children's risk of leukemia. On the other hand, many experimental studies have raised the possibility that low doses of ionizing radiation may not be harmful or may even produce stimulating or adaptive responses. The term 'hormesis' has come to be used to describe these phenomena produced by low doses of ionizing radiation when they were beneficial for the organisms studied. At the end of the International Conference on Low Dose Irradiation one conclusion appeared to be justified: radiation produces an adaptive response, though it is not universally detected yet. The conference failed to obtain any consensus on risk assessment at low doses, but raised many problems to be dealt with by future studies. The editors therefore believe that the Proceedings will be useful for all scientists and people concerned with radiation protection and the biological effects of low-dose irradiation

  17. Modeling the mechanisms of biological GTP hydrolysis

    DEFF Research Database (Denmark)

    Carvalho, Alexandra T.P.; Szeler, Klaudia; Vavitsas, Konstantinos

    2015-01-01

    Enzymes that hydrolyze GTP are currently in the spotlight, due to their molecular switch mechanism that controls many cellular processes. One of the best-known classes of these enzymes are small GTPases such as members of the Ras superfamily, which catalyze the hydrolysis of the γ-phosphate bond...... in GTP. In addition, the availability of an increasing number of crystal structures of translational GTPases such as EF-Tu and EF-G have made it possible to probe the molecular details of GTP hydrolysis on the ribosome. However, despite a wealth of biochemical, structural and computational data, the way...

  18. CRISPR-Cas: biology, mechanisms and relevance

    Science.gov (United States)

    Hille, Frank

    2016-01-01

    Prokaryotes have evolved several defence mechanisms to protect themselves from viral predators. Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated proteins (Cas) display a prokaryotic adaptive immune system that memorizes previous infections by integrating short sequences of invading genomes—termed spacers—into the CRISPR locus. The spacers interspaced with repeats are expressed as small guide CRISPR RNAs (crRNAs) that are employed by Cas proteins to target invaders sequence-specifically upon a reoccurring infection. The ability of the minimal CRISPR-Cas9 system to target DNA sequences using programmable RNAs has opened new avenues in genome editing in a broad range of cells and organisms with high potential in therapeutical applications. While numerous scientific studies have shed light on the biochemical processes behind CRISPR-Cas systems, several aspects of the immunity steps, however, still lack sufficient understanding. This review summarizes major discoveries in the CRISPR-Cas field, discusses the role of CRISPR-Cas in prokaryotic immunity and other physiological properties, and describes applications of the system as a DNA editing technology and antimicrobial agent. This article is part of the themed issue ‘The new bacteriology’. PMID:27672148

  19. Mechanics of Biological Tissues and Biomaterials: Current Trends

    Directory of Open Access Journals (Sweden)

    Amir A. Zadpoor

    2015-07-01

    Full Text Available Investigation of the mechanical behavior of biological tissues and biomaterials has been an active area of research for several decades. However, in recent years, the enthusiasm in understanding the mechanical behavior of biological tissues and biomaterials has increased significantly due to the development of novel biomaterials for new fields of application, along with the emergence of advanced computational techniques. The current Special Issue is a collection of studies that address various topics within the general theme of “mechanics of biomaterials”. This editorial aims to present the context within which the studies of this Special Issue could be better understood. I, therefore, try to identify some of the most important research trends in the study of the mechanical behavior of biological tissues and biomaterials.

  20. Mechanisms of leading edge protrusion in interstitial migration

    Science.gov (United States)

    Wilson, Kerry; Lewalle, Alexandre; Fritzsche, Marco; Thorogate, Richard; Duke, Tom; Charras, Guillaume

    2013-01-01

    While the molecular and biophysical mechanisms underlying cell protrusion on two-dimensional substrates are well understood, our knowledge of the actin structures driving protrusion in three-dimensional environments is poor, despite relevance to inflammation, development and cancer. Here we report that, during chemotactic migration through microchannels with 5 μm × 5 μm cross-sections, HL60 neutrophil-like cells assemble an actin-rich slab filling the whole channel cross-section at their front. This leading edge comprises two distinct F-actin networks: an adherent network that polymerizes perpendicular to cell-wall interfaces and a ‘free’ network that grows from the free membrane at the cell front. Each network is polymerized by a distinct nucleator and, due to their geometrical arrangement, the networks interact mechanically. On the basis of our experimental data, we propose that, during interstitial migration, medial growth of the adherent network compresses the free network preventing its retrograde movement and enabling new polymerization to be converted into forward protrusion. PMID:24305616

  1. On the mechanism of the biological effect of ionizing radiation

    International Nuclear Information System (INIS)

    Margulis, M.A.; Margulis, I.M.

    2005-01-01

    The mechanisms of the biological effects of ionizing radiation (IR) and ultrasound (US) were considered. The current views on the nature of toxicity of IR, which is usually assigned to the formation of radicals in living tissues and to the straight-line collision of an ionizing particle with the DNA molecule, were analyzed. It was established that the amount of radicals formed in biological tissues in conditions of ultrasonically induced cavitation can be as large as that for IR; however, the biological effect of US is much softer as compared to IR. It was shown that the contribution of the indirect mechanism to the total biological effect of IR can be estimated by comparing US and IR in their chemical action; the contribution of the indirect mechanism to the biological effect of IR was found to be negligibly small. An alternative mechanism was proposed to explain the biological effect of IR. In accordance with the proposed model, IR with a high linear energy transfer (LET) value breaks through cell walls and biological membranes and causes damage to them, such that the cell can lose its regenerative capacity. Moreover, high-energy heavy ionizing particles perforate cytoplasm to form channels. Ionizing radiation with a low LET value (γ- and X-rays) causes multiple damages to biological membranes. Ionizing particles can also cause damages to membranes of mitochondria thus affecting the mechanism of cellular respiration, which will cause neoplastic diseases. The straight-line collision of an ionizing particle with a DNA molecule was found to be 5-7 orders of magnitude less probable as compared to the collision with a wall or membrane. It was shown that multiple perforations of cell walls and damages to membranes are characteristic only of ionizing particles, which have sufficiently long tracks, and do not occur upon exposure to ultrasonic waves, microwaves, UV radiation, and magnetic fields [ru

  2. Molecular biological mechanism II. Molecular mechanisms of cell cycle regulation

    International Nuclear Information System (INIS)

    Jung, T.

    2000-01-01

    The cell cycle in eukaryotes is regulated by central cell cycle controlling protein kinase complexes. These protein kinase complexes consist of a catalytic subunit from the cyclin-dependent protein kinase family (CDK), and a regulatory subunit from the cyclin family. Cyclins are characterised by their periodic cell cycle related synthesis and destruction. Each cell cycle phase is characterised by a specific set of CDKs and cyclins. The activity of CDK/cyclin complexes is mainly regulated on four levels. It is controlled by specific phosphorylation steps, the synthesis and destruction of cyclins, the binding of specific inhibitor proteins, and by active control of their intracellular localisation. At several critical points within the cell cycle, named checkpoints, the integrity of the cellular genome is monitored. If damage to the genome or an unfinished prior cell cycle phase is detected, the cell cycle progression is stopped. These cell cycle blocks are of great importance to secure survival of cells. Their primary importance is to prevent the manifestation and heritable passage of a mutated genome to daughter cells. Damage sensing, DNA repair, cell cycle control and apoptosis are closely linked cellular defence mechanisms to secure genome integrity. Disregulation in one of these defence mechanisms are potentially correlated with an increased cancer risk and therefore in at least some cases with an increased radiation sensitivity. (orig.) [de

  3. Formamidopyrimidines in DNA: mechanisms of formation, repair, and biological effects.

    Science.gov (United States)

    Dizdaroglu, Miral; Kirkali, Güldal; Jaruga, Pawel

    2008-12-15

    Oxidatively induced damage to DNA results in a plethora of lesions comprising modified bases and sugars, DNA-protein cross-links, tandem lesions, strand breaks, and clustered lesions. Formamidopyrimidines, 4,6-diamino-5-formamidopyrimidine (FapyAde) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua), are among the major lesions generated in DNA by hydroxyl radical attack, UV radiation, or photosensitization under numerous in vitro and in vivo conditions. They are formed by one-electron reduction of C8-OH-adduct radicals of purines and thus have a common precursor with 8-hydroxypurines generated upon one-electron oxidation. Methodologies using mass spectrometry exist to accurately measure FapyAde and FapyGua in vitro and in vivo. Formamidopyrimidines are repaired by base excision repair. Numerous prokaryotic and eukaryotic DNA glycosylases are highly specific for removal of these lesions from DNA in the first step of this repair pathway, indicating their biological importance. FapyAde and FapyGua are bypassed by DNA polymerases with the insertion of the wrong intact base opposite them, leading to mutagenesis. In mammalian cells, the mutagenicity of FapyGua exceeds that of 8-hydroxyguanine, which is thought to be the most mutagenic of the oxidatively induced lesions in DNA. The background and formation levels of the former in vitro and in vivo equal or exceed those of the latter under various conditions. FapyAde and FapyGua exist in living cells at significant background levels and are abundantly generated upon exposure to oxidative stress. Mice lacking the genes that encode specific DNA glycosylases accumulate these lesions in different organs and, in some cases, exhibit a series of pathological conditions including metabolic syndrome and cancer. Animals exposed to environmental toxins accumulate formamidopyrimidines in their organs. Here, we extensively review the mechanisms of formation, measurement, repair, and biological effects of formamidopyrimidines

  4. Mechanisms by Which Dehydration May Lead to Chronic Kidney Disease.

    Science.gov (United States)

    Roncal-Jimenez, C; Lanaspa, M A; Jensen, T; Sanchez-Lozada, L G; Johnson, R J

    2015-01-01

    Dehydration, a condition that characterizes excessive loss of body water, is well known to be associated with acute renal dysfunction; however, it has largely been considered reversible and to be associated with no long-term effects on the kidney. Recently, an epidemic of chronic kidney disease has emerged in Central America in which the major risk factor seems to be recurrent heat-associated dehydration. This has led to studies investigating whether recurrent dehydration may lead to permanent kidney damage. Three major potential mechanisms have been identified, including the effects of vasopressin on the kidney, the activation of the aldose reductase-fructokinase pathway, and the effects of chronic hyperuricemia. The discovery of these pathways has also led to the recognition that mild dehydration may be a risk factor in progression of all types of chronic kidney diseases. Furthermore, there is some evidence that increasing hydration, particularly with water, may actually prevent CKD. Thus, a whole new area of investigation is developing that focuses on the role of water and osmolarity and their influence on kidney function and health. © 2015 S. Karger AG, Basel.

  5. Nondestructive mechanical characterization of developing biological tissues using inflation testing.

    Science.gov (United States)

    Oomen, P J A; van Kelle, M A J; Oomens, C W J; Bouten, C V C; Loerakker, S

    2017-10-01

    One of the hallmarks of biological soft tissues is their capacity to grow and remodel in response to changes in their environment. Although it is well-accepted that these processes occur at least partly to maintain a mechanical homeostasis, it remains unclear which mechanical constituent(s) determine(s) mechanical homeostasis. In the current study a nondestructive mechanical test and a two-step inverse analysis method were developed and validated to nondestructively estimate the mechanical properties of biological tissue during tissue culture. Nondestructive mechanical testing was achieved by performing an inflation test on tissues that were cultured inside a bioreactor, while the tissue displacement and thickness were nondestructively measured using ultrasound. The material parameters were estimated by an inverse finite element scheme, which was preceded by an analytical estimation step to rapidly obtain an initial estimate that already approximated the final solution. The efficiency and accuracy of the two-step inverse method was demonstrated on virtual experiments of several material types with known parameters. PDMS samples were used to demonstrate the method's feasibility, where it was shown that the proposed method yielded similar results to tensile testing. Finally, the method was applied to estimate the material properties of tissue-engineered constructs. Via this method, the evolution of mechanical properties during tissue growth and remodeling can now be monitored in a well-controlled system. The outcomes can be used to determine various mechanical constituents and to assess their contribution to mechanical homeostasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Quantum mechanical simulation methods for studying biological systems

    International Nuclear Information System (INIS)

    Bicout, D.; Field, M.

    1996-01-01

    Most known biological mechanisms can be explained using fundamental laws of physics and chemistry and a full understanding of biological processes requires a multidisciplinary approach in which all the tools of biology, chemistry and physics are employed. An area of research becoming increasingly important is the theoretical study of biological macromolecules where numerical experimentation plays a double role of establishing a link between theoretical models and predictions and allowing a quantitative comparison between experiments and models. This workshop brought researchers working on different aspects of the development and application of quantum mechanical simulation together, assessed the state-of-the-art in the field and highlighted directions for future research. Fourteen lectures (theoretical courses and specialized seminars) deal with following themes: 1) quantum mechanical calculations of large systems, 2) ab initio molecular dynamics where the calculation of the wavefunction and hence the energy and forces on the atoms for a system at a single nuclear configuration are combined with classical molecular dynamics algorithms in order to perform simulations which use a quantum mechanical potential energy surface, 3) quantum dynamical simulations, electron and proton transfer processes in proteins and in solutions and finally, 4) free seminars that helped to enlarge the scope of the workshop. (N.T.)

  7. Early mechanisms in radiation-induced biological damage

    International Nuclear Information System (INIS)

    Powers, E.L.

    1983-01-01

    An introduction to the mechanisms of radiation action in biological systems is presented. Several questions about the nature of the radiation damage process are discussed, including recognition of the oxygen effects, dose-response relationships, and the importance of the hydroxyl radical

  8. Renal manifestations of chronic lead poisoning: clinical, biological, and histological study

    Energy Technology Data Exchange (ETDEWEB)

    Devulder, B; Martin, J C; Mathot, J; Dequiedt, P; Durocher, A; Vanhille, P; Tacquet, A

    1974-01-01

    Clinical observation of a metal worker who showed, after exposure to lead, biological disturbances typical of lead poisoning, associated with very discrete azotaemia. In-depth nephrological exploration by electronic microscope showed the existence of intra-cytoplasmic inclusions, intra-nuclear corpuscles and mitochondrial changes, without significant impairment of renal function. This case brings the authors to analyse the more recently discovered clinical, biological and histological aspects of the kidneys in chronic lead poisoning and to draw conclusions concerning prognosis and medico-legal aspects. As regards therapy, the use of chelating agents, on account of the sudden liberation of the toxic metal it causes, seems liable to aggravate kidney and other damage, and should therefore be administered under strict medical supervision.

  9. The void nucleation mechanism within lead phase during spallation of leaded brass

    Science.gov (United States)

    Yang, Yang; Wang, Can; Chen, Xingzhi; Chen, Kaiguo; Hu, Haibo; Fu, Yanan

    2018-07-01

    The incipient spall behaviours of Cu-34%Zn-3%Pb leaded brass samples with annealed and cryogenic-treated conditions were loaded using one-stage light gas gun experiments. The effect of Pb-phase on dynamic damage nucleation in leaded brass specimens was investigated by means of optical microscopy, scanning electron microscopy and x-ray computer tomography. It was found that the voids of incipient spall were mainly nucleated in the interior of the lead (no tensile stress would be produced within lead according to the impact theory) instead of nucleated at the phase interface as expected by quasi-static damage fracture theory. A nucleation model is proposed in the present work that is the asymmetry high compression zones in the centre of the lead-phase were formed by the rarefaction wave convergence effects of matrix/quasi-spherical lead interface, which caused adiabatic temperature rise that exceeded melting point of lead due to severe plastic deformation, finally led to local melting and void nucleation. In addition, the spall strength and damage rate increased with the increase in the Pb-phase number.

  10. Excretion of lead and its biological activity several years after termination of exposure

    Science.gov (United States)

    Přerovská, I.; Teisinger, J.

    1970-01-01

    Přerovská, and Teisinger, J. (1970).Brit. J. industr. Med.,27, 352-355. Excretion of lead and its biological activity several years after termination of exposure. A group of 27 persons who had been treated some years previously for chronic lead poisoning at our clinic, and who had not come into occupational contact with lead since, was examined. Half of them had had no occupational exposure to lead for 3 to 5 years and the others for 8 to 17 years. In most of these persons there is still an increased lead excretion, originating from an increased deposit in the bones. The mobilization test after calcium versenate (CaEDTA) injection was greater than 0·350 mg/24 hours. The values found for haemoglobin, punctate basophilia, coproporphyrin and ALA in urine were normal, but there was, in all cases, a decreased ALA-D activity. This finding suggests biological activity of such negligible lead flow many years after termination of exposure. PMID:5488694

  11. Nanomaterials modulate stem cell differentiation: biological interaction and underlying mechanisms.

    Science.gov (United States)

    Wei, Min; Li, Song; Le, Weidong

    2017-10-25

    Stem cells are unspecialized cells that have the potential for self-renewal and differentiation into more specialized cell types. The chemical and physical properties of surrounding microenvironment contribute to the growth and differentiation of stem cells and consequently play crucial roles in the regulation of stem cells' fate. Nanomaterials hold great promise in biological and biomedical fields owing to their unique properties, such as controllable particle size, facile synthesis, large surface-to-volume ratio, tunable surface chemistry, and biocompatibility. Over the recent years, accumulating evidence has shown that nanomaterials can facilitate stem cell proliferation and differentiation, and great effort is undertaken to explore their possible modulating manners and mechanisms on stem cell differentiation. In present review, we summarize recent progress in the regulating potential of various nanomaterials on stem cell differentiation and discuss the possible cell uptake, biological interaction and underlying mechanisms.

  12. Pannus-Related Mechanical Valve Dysfunction Leading to Hemodynamic Shock

    Directory of Open Access Journals (Sweden)

    Manabu Shiraishi

    2012-02-01

    Full Text Available Mechanical prosthetic valve dysfunction caused by pannus formation is rare. Pannus restricts movement of prosthetic valve leaflets, resulting in severe aortic regurgitation. We describe the case of a 77-year-old woman who presented to the emergency room with increasing dyspnea, ischemia, and shock secondary to mechanical aortic valve dysfunction. Transesophageal echocardiography showed a blockade of the leaflets of the mechanical aortic valve, with severe aortic regurgitation. She underwent emergent cardiac surgery for aortic valve replacement. Pannus formation should be considered as a potential cause of acute severe aortic regurgitation in a patient with a small-sized mechanical aortic prosthesis in the supra-annular position. On a pathological exam, extensive pannus was found on the ventricular side of the prosthetic valve, extending from the ring into the central orifice. [Arch Clin Exp Surg 2012; 1(1.000: 50-53

  13. Basic Mechanisms Leading to Fatigue Failure of Structural Materials

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Petráš, Roman; Mazánová, Veronika

    2016-01-01

    Roč. 69, č. 2 (2016), s. 289-294 ISSN 0972-2815. [International Conference on CREEP , FATIGUE and CREEP -FATIGUE INTERACTION /7./. Kalpakkam, 19.01.2016-22.01.2016] R&D Projects: GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : Damage mechanism * Fatigue crack initiation * Austenitic steel * Oxide cracking Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.533, year: 2016

  14. Biological timing and the clock metaphor: oscillatory and hourglass mechanisms.

    Science.gov (United States)

    Rensing, L; Meyer-Grahle, U; Ruoff, P

    2001-05-01

    Living organisms have developed a multitude of timing mechanisms--"biological clocks." Their mechanisms are based on either oscillations (oscillatory clocks) or unidirectional processes (hourglass clocks). Oscillatory clocks comprise circatidal, circalunidian, circadian, circalunar, and circannual oscillations--which keep time with environmental periodicities--as well as ultradian oscillations, ovarian cycles, and oscillations in development and in the brain, which keep time with biological timescales. These clocks mainly determine time points at specific phases of their oscillations. Hourglass clocks are predominantly found in development and aging and also in the brain. They determine time intervals (duration). More complex timing systems combine oscillatory and hourglass mechanisms, such as the case for cell cycle, sleep initiation, or brain clocks, whereas others combine external and internal periodicities (photoperiodism, seasonal reproduction). A definition of a biological clock may be derived from its control of functions external to its own processes and its use in determining temporal order (sequences of events) or durations. Biological and chemical oscillators are characterized by positive and negative feedback (or feedforward) mechanisms. During evolution, living organisms made use of the many existing oscillations for signal transmission, movement, and pump mechanisms, as well as for clocks. Some clocks, such as the circadian clock, that time with environmental periodicities are usually compensated (stabilized) against temperature, whereas other clocks, such as the cell cycle, that keep time with an organismic timescale are not compensated. This difference may be related to the predominance of negative feedback in the first class of clocks and a predominance of positive feedback (autocatalytic amplification) in the second class. The present knowledge of a compensated clock (the circadian oscillator) and an uncompensated clock (the cell cycle), as well

  15. The mechanism for the primary biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Byakov, Vsevolod M; Stepanov, Sergei V

    2006-01-01

    The primary biological response of living organisms to the passage of fast charged particles is traditionally believed to be dominated by the chemical reactions of the radical products from the radiolysis of cellular water (OH, H, e aq - , O 2 - , H 2 O 2 ) and by the bioradicals that they produce (and which can also result from the direct electronic activation of biomolecules). This understanding has provided insight into how ionizing radiations affect biological systems and, most importantly, what radioprotection and radiosensibilizing effects are produced by chemical compounds introduced into an organism. However, a number of key radiobiological facts remain unexplained by the current theory, stimulating a search for other biologically active factors that may be triggered by radiation. This review examines a fact that is usually ignored in discussing the biological impact of ionizing radiation: the local increase in acidity in the water solution along the track of a charged particle. The acidity in the track is very different from its value for cellular water in a living organism. Biological processes are well-known to be highly sensitive to changes in the environmental acidity. It seems that the biological impact of ionizing radiations is dominated not by the water radiolysis products (mostly radicals) listed above but particles of a different nature, hydroxonium ions H 3 O + , where the term hydroxonium refer to protonated water molecules. This modification of the mechanism of primary radiobiological effects is in good agreement with experimental data. In particular, the extremal dependence of the relative biological efficiency (RBE) of radiations on their ionizing energy losses is accounted for in quantitative terms, as is the increase in the RBE in the relativistic energy range. (reviews of topical problems)

  16. Molecular and cellular mechanisms that lead to Candida biofilm formation

    NARCIS (Netherlands)

    ten Cate, J.M.; Klis, F.M.; Pereira-Cenci, T.; Crielaard, W.; de Groot, P.W.J.

    2009-01-01

    Fungal infections in the oral cavity are mainly caused by C. albicans, but other Candida species are also frequently identified. They are increasing in prevalence, especially in denture-wearers and aging people, and may lead to invasive infections, which have a high mortality rate. Attachment to

  17. Interaction mechanisms and biological effects of static magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tenforde, T.S.

    1994-06-01

    Mechanisms through which static magnetic fields interact with living systems are described and illustrated by selected experimental observations. These mechanisms include electrodynamic interactions with moving, ionic charges (blood flow and nerve impulse conduction), magnetomechanical interactions (orientation and translation of molecules structures and magnetic particles), and interactions with electronic spin states in charge transfer reactions (photo-induced electron transfer in photosynthesis). A general summary is also presented of the biological effects of static magnetic fields. There is convincing experimental evidence for magnetoreception mechanisms in several classes of lower organisms, including bacteria and marine organisms. However, in more highly evolved species of animals, there is no evidence that the interactions of static magnetic fields with flux densities up to 2 Tesla (1 Tesla [T] = 10{sup 4} Gauss) produce either behavioral or physiolocical alterations. These results, based on controlled studies with laboratory animals, are consistent with the outcome of recent epidemiological surveys on human populations exposed occupationally to static magnetic fields.

  18. Elastic Multi-scale Mechanisms: Computation and Biological Evolution.

    Science.gov (United States)

    Diaz Ochoa, Juan G

    2018-01-01

    Explanations based on low-level interacting elements are valuable and powerful since they contribute to identify the key mechanisms of biological functions. However, many dynamic systems based on low-level interacting elements with unambiguous, finite, and complete information of initial states generate future states that cannot be predicted, implying an increase of complexity and open-ended evolution. Such systems are like Turing machines, that overlap with dynamical systems that cannot halt. We argue that organisms find halting conditions by distorting these mechanisms, creating conditions for a constant creativity that drives evolution. We introduce a modulus of elasticity to measure the changes in these mechanisms in response to changes in the computed environment. We test this concept in a population of predators and predated cells with chemotactic mechanisms and demonstrate how the selection of a given mechanism depends on the entire population. We finally explore this concept in different frameworks and postulate that the identification of predictive mechanisms is only successful with small elasticity modulus.

  19. A Systems Biology Approach Reveals Converging Molecular Mechanisms that Link Different POPs to Common Metabolic Diseases.

    Science.gov (United States)

    Ruiz, Patricia; Perlina, Ally; Mumtaz, Moiz; Fowler, Bruce A

    2016-07-01

    A number of epidemiological studies have identified statistical associations between persistent organic pollutants (POPs) and metabolic diseases, but testable hypotheses regarding underlying molecular mechanisms to explain these linkages have not been published. We assessed the underlying mechanisms of POPs that have been associated with metabolic diseases; three well-known POPs [2,3,7,8-tetrachlorodibenzodioxin (TCDD), 2,2´,4,4´,5,5´-hexachlorobiphenyl (PCB 153), and 4,4´-dichlorodiphenyldichloroethylene (p,p´-DDE)] were studied. We used advanced database search tools to delineate testable hypotheses and to guide laboratory-based research studies into underlying mechanisms by which this POP mixture could produce or exacerbate metabolic diseases. For our searches, we used proprietary systems biology software (MetaCore™/MetaDrug™) to conduct advanced search queries for the underlying interactions database, followed by directional network construction to identify common mechanisms for these POPs within two or fewer interaction steps downstream of their primary targets. These common downstream pathways belong to various cytokine and chemokine families with experimentally well-documented causal associations with type 2 diabetes. Our systems biology approach allowed identification of converging pathways leading to activation of common downstream targets. To our knowledge, this is the first study to propose an integrated global set of step-by-step molecular mechanisms for a combination of three common POPs using a systems biology approach, which may link POP exposure to diseases. Experimental evaluation of the proposed pathways may lead to development of predictive biomarkers of the effects of POPs, which could translate into disease prevention and effective clinical treatment strategies. Ruiz P, Perlina A, Mumtaz M, Fowler BA. 2016. A systems biology approach reveals converging molecular mechanisms that link different POPs to common metabolic diseases. Environ

  20. Quantum selfish gene (biological evolution in terms of quantum mechanics)

    OpenAIRE

    Ozhigov, Yuri I.

    2013-01-01

    I propose to treat the biological evolution of genoms by means of quantum mechanical tools. We start with the concept of meta- gene, which specifies the "selfish gene" of R.Dawkins. Meta- gene encodes the abstract living unity, which can live relatively independently of the others, and can contain a few real creatures. Each population of living creatures we treat as the wave function on meta- genes, which module squared is the total number of creatures with the given meta-gene, and the phase ...

  1. Biological and societal dimensions of lead poisoning in birds in the USA

    Science.gov (United States)

    Friend, Milton; Franson, J. Christian; Anderson, William L.

    2008-01-01

    The ingestion of spent lead shot was known to cause mortality in wild waterfowl in the US a century before the implementation of nontoxic shot regulations began in 1972. The biological foundation for this transition was strongly supported by both field observations and structured scientific investigations. Despite the overwhelming evidence, various societal factors forestalled the full transition to nontoxic shot for waterfowl hunting until 1991. Now, nearly 20 years later, these same factors weigh heavily in current debates about nontoxic shot requirements for hunting other game birds, requiring nontoxic bullets for big game hunting in California Condor range and for restricting the use of small lead sinkers and jig heads for sport-fishing. As with waterfowl, a strong science-based foundation is requisite for further transitions to nontoxic ammunition and fishing weights. Our experiences have taught us that the societal aspects of this transition are as important as the biological components and must be adequately addressed before alternatives to toxic lead ammunition, fishing weights, and other materials will be accepted as an investment in wildlife conservation.

  2. Mechanism of electric fatigue crack growth in lead zirconate titanate

    International Nuclear Information System (INIS)

    Westram, Ilona; Oates, William S.; Lupascu, Doru C.; Roedel, Juergen; Lynch, Christopher S.

    2007-01-01

    A series of experiments was performed with through-thickness cracks in ferroelectric double cantilever beam (DCB) specimens. Cyclic electric fields of different amplitudes were applied which resulted in cyclic crack propagation perpendicular to the electric field direction. Crack propagation was observed optically and three regimes were identified: a pop-in from a notch, steady-state crack growth and a decrease of the crack growth rate with increasing cycle number. Crack growth only occurred if the applied field exceeded the coercive field strength of the material. Furthermore, the crack extended during each field reversal and the crack growth rate increased with increasing field. Based on the experimental observations, a mechanistic understanding was developed and contrasted with a nonlinear finite element analysis which quantified the stress intensity in the DCB specimens. The driving forces for crack formation at the notch and subsequent fatigue crack growth were computed based on the distribution of residual stresses due to ferroelectric switching. The finite element results are in good agreement with the experimental observations and support the proposed mechanism

  3. Biology teachers' dissection practices and the influences that lead to their adoption: An exploratory research

    Science.gov (United States)

    Milano, Regina Nicole

    The lack of resolution in the on-going animal dissection debate inspired this mixed methods study to identify Connecticut secondary biology teachers' dissection practices and the influences that lead to their adoption. Qualitative findings indicate past experiences, managing objections to dissection, school culture, goals of biology teaching and ethics as major influences on dissection practices with 58.4% (n=7) of the sample dissecting and 41.6% not dissecting (n=5). Quantitative findings reveal gender, standards and curriculum, advantages of dissection and experiences as a student as major influences on dissection practices with 71.9% (n=92) of the sample dissecting and 28.1% (n=36) not dissecting. The study concludes that dissection policies are necessary and imminent in Connecticut school districts. Furthermore, it advises teacher-initiated, qualitative and quantitative assessments to expose disparities between student dissection perspectives and their own, prior to conducting dissection. Finally, it provides suggestions for addressing potential differences including administrative involvement.

  4. Lactose Intolerance in Adults: Biological Mechanism and Dietary Management.

    Science.gov (United States)

    Deng, Yanyong; Misselwitz, Benjamin; Dai, Ning; Fox, Mark

    2015-09-18

    Lactose intolerance related to primary or secondary lactase deficiency is characterized by abdominal pain and distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products. The biological mechanism and lactose malabsorption is established and several investigations are available, including genetic, endoscopic and physiological tests. Lactose intolerance depends not only on the expression of lactase but also on the dose of lactose, intestinal flora, gastrointestinal motility, small intestinal bacterial overgrowth and sensitivity of the gastrointestinal tract to the generation of gas and other fermentation products of lactose digestion. Treatment of lactose intolerance can include lactose-reduced diet and enzyme replacement. This is effective if symptoms are only related to dairy products; however, lactose intolerance can be part of a wider intolerance to variably absorbed, fermentable oligo-, di-, monosaccharides and polyols (FODMAPs). This is present in at least half of patients with irritable bowel syndrome (IBS) and this group requires not only restriction of lactose intake but also a low FODMAP diet to improve gastrointestinal complaints. The long-term effects of a dairy-free, low FODMAPs diet on nutritional health and the fecal microbiome are not well defined. This review summarizes recent advances in our understanding of the genetic basis, biological mechanism, diagnosis and dietary management of lactose intolerance.

  5. Training to Improve Hearing Speech in Noise: Biological Mechanisms

    Science.gov (United States)

    Song, Judy H.; Skoe, Erika; Banai, Karen

    2012-01-01

    We investigated training-related improvements in listening in noise and the biological mechanisms mediating these improvements. Training-related malleability was examined using a program that incorporates cognitively based listening exercises to improve speech-in-noise perception. Before and after training, auditory brainstem responses to a speech syllable were recorded in quiet and multitalker noise from adults who ranged in their speech-in-noise perceptual ability. Controls did not undergo training but were tested at intervals equivalent to the trained subjects. Trained subjects exhibited significant improvements in speech-in-noise perception that were retained 6 months later. Subcortical responses in noise demonstrated training-related enhancements in the encoding of pitch-related cues (the fundamental frequency and the second harmonic), particularly for the time-varying portion of the syllable that is most vulnerable to perceptual disruption (the formant transition region). Subjects with the largest strength of pitch encoding at pretest showed the greatest perceptual improvement. Controls exhibited neither neurophysiological nor perceptual changes. We provide the first demonstration that short-term training can improve the neural representation of cues important for speech-in-noise perception. These results implicate and delineate biological mechanisms contributing to learning success, and they provide a conceptual advance to our understanding of the kind of training experiences that can influence sensory processing in adulthood. PMID:21799207

  6. Lactose Intolerance in Adults: Biological Mechanism and Dietary Management

    Directory of Open Access Journals (Sweden)

    Yanyong Deng

    2015-09-01

    Full Text Available Lactose intolerance related to primary or secondary lactase deficiency is characterized by abdominal pain and distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products. The biological mechanism and lactose malabsorption is established and several investigations are available, including genetic, endoscopic and physiological tests. Lactose intolerance depends not only on the expression of lactase but also on the dose of lactose, intestinal flora, gastrointestinal motility, small intestinal bacterial overgrowth and sensitivity of the gastrointestinal tract to the generation of gas and other fermentation products of lactose digestion. Treatment of lactose intolerance can include lactose-reduced diet and enzyme replacement. This is effective if symptoms are only related to dairy products; however, lactose intolerance can be part of a wider intolerance to variably absorbed, fermentable oligo-, di-, monosaccharides and polyols (FODMAPs. This is present in at least half of patients with irritable bowel syndrome (IBS and this group requires not only restriction of lactose intake but also a low FODMAP diet to improve gastrointestinal complaints. The long-term effects of a dairy-free, low FODMAPs diet on nutritional health and the fecal microbiome are not well defined. This review summarizes recent advances in our understanding of the genetic basis, biological mechanism, diagnosis and dietary management of lactose intolerance.

  7. Review: Bioenergetic Fields and Their Biologic Effects Mechanism

    Directory of Open Access Journals (Sweden)

    Zahra Movaffaghi

    2007-04-01

    Full Text Available As interests in complementary and alternative medicine grows, the scientists are looking forward in researches which determine the mechanisms in which they exert their effectiveness. Some of these modalities like Yoga, Acupuncture, and especially other bio-field therapies such as none contact therapeutic touch, affects the bio-field which spreads throughout the body and into the space around it. According to physic’s law, when electricity flows throw the living tissues, like what happens in our heart and brain, biomagnetic fields are being induced in the surrounding space. Beside that moving charges like ions and free radicals which finally produce electromagnetic fields. Using very sensitive magnetometers, biomagnetic fields have been detected and get amplified up to 1000 times by meditation. This phenomenon could be the basis for most of most complementaty therapeutic approaches like therapeutic touch. On the other hand the electrical, magnetic and bio-magnetic fields have a well known application in conventional medicine. Modern research about bio-magnetism and magneto-biology suggests that in term of both aspects, the effects and the mechanisms for all the different looking modalities used in conventional medicine and complementary medicine which have commons in their fundamentals. This article reviews some of the recent works on biological effects of natural or artificial electromagnetic fields.

  8. On the mechanism of biological activation by tritium.

    Science.gov (United States)

    Rozhko, T V; Badun, G A; Razzhivina, I A; Guseynov, O A; Guseynova, V E; Kudryasheva, N S

    2016-06-01

    The mechanism of biological activation by beta-emitting radionuclide tritium was studied. Luminous marine bacteria were used as a bioassay to monitor the biological effect of tritium with luminescence intensity as the physiological parameter tested. Two different types of tritium sources were used: HTO molecules distributed regularly in the surrounding aqueous medium, and a solid source with tritium atoms fixed on its surface (tritium-labeled films, 0.11, 0.28, 0.91, and 2.36 MBq/cm(2)). When using the tritium-labeled films, tritium penetration into the cells was prevented. The both types of tritium sources revealed similar changes in the bacterial luminescence kinetics: a delay period followed by bioluminescence activation. No monotonic dependences of bioluminescence activation efficiency on specific radioactivities of the films were found. A 15-day exposure to tritiated water (100 MBq/L) did not reveal mutations in bacterial DNA. The results obtained give preference to a "non-genomic" mechanism of bioluminescence activation by tritium. An activation of the intracellular bioluminescence process develops without penetration of tritium atoms into the cells and can be caused by intensification of trans-membrane cellular processes stimulated by ionization and radiolysis of aqueous media. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles.

    Directory of Open Access Journals (Sweden)

    Olga Kononova

    2016-01-01

    Full Text Available The mechanical properties of virus capsids correlate with local conformational dynamics in the capsid structure. They also reflect the required stability needed to withstand high internal pressures generated upon genome loading and contribute to the success of important events in viral infectivity, such as capsid maturation, genome uncoating and receptor binding. The mechanical properties of biological nanoparticles are often determined from monitoring their dynamic deformations in Atomic Force Microscopy nanoindentation experiments; but a comprehensive theory describing the full range of observed deformation behaviors has not previously been described. We present a new theory for modeling dynamic deformations of biological nanoparticles, which considers the non-linear Hertzian deformation, resulting from an indenter-particle physical contact, and the bending of curved elements (beams modeling the particle structure. The beams' deformation beyond the critical point triggers a dynamic transition of the particle to the collapsed state. This extreme event is accompanied by a catastrophic force drop as observed in the experimental or simulated force (F-deformation (X spectra. The theory interprets fine features of the spectra, including the nonlinear components of the FX-curves, in terms of the Young's moduli for Hertzian and bending deformations, and the structural damage dependent beams' survival probability, in terms of the maximum strength and the cooperativity parameter. The theory is exemplified by successfully describing the deformation dynamics of natural nanoparticles through comparing theoretical curves with experimental force-deformation spectra for several virus particles. This approach provides a comprehensive description of the dynamic structural transitions in biological and artificial nanoparticles, which is essential for their optimal use in nanotechnology and nanomedicine applications.

  10. Purification and concentration of lead samples in biological monitoring of occupational exposures

    Directory of Open Access Journals (Sweden)

    A Rahimi-Froushani

    2006-04-01

    Full Text Available Background and Aims:Lead is an important environmental constituent widely used in industrialprocesses for production of synthetic materials and therefore can be released in the environmentcausing public exposure especially around the industrial residence area. For evaluation of humanexposure to trace toxic metal of Pb (II, environmental and biological monitoring are essentialprocesses, in which, preparation of such samples is one of the most time-consuming and errorproneaspects prior to analysis. The use of solid-phase extraction (SPE has grown and is a fertiletechnique of sample preparation as it provides better results than those produced by liquid-liquidextraction (LLE. The aim of this study was to investigate factors influencing sample pretreatmentfor trace analysis of lead in biological samples for evaluation of occupational exposure.Method :To evaluate factors influencing quantitative analysis scheme of lead, solid phaseextraction using mini columns filled with XAD-4 resin was optimized with regard to sample pH,ligand concentration, loading flow rate, elution solvent, sample volume (up to 500 ml, elutionvolume, amount of resins, and sample matrix interferences.Results :Lead was retained on solid sorbent and eluted followed by simple determination ofanalytes by using flame atomic absorption spectrometery. Obtained recoveries of the metal ionwere more than 92%. The amount of the analyte detected after simultaneous pre-concentrationwas basically in agreement with the added amounts. The optimized procedure was also validatedwith three different pools of spiked urine samples and showed a good reproducibility over sixconsecutive days as well as six within-day experiments. The developed method promised to beapplicable for evaluation of other metal ions present in different environmental and occupationalsamples as suitable results were obtained for relative standard deviation (less than 10%.Conclusion:This optimized method can be considered to be

  11. Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B.

    Science.gov (United States)

    Naik, Milind Mohan; Pandey, Anju; Dubey, Santosh Kumar

    2012-09-01

    A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6 mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108 mg/L dry weight when exposed to 1.6 mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6 mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6 mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17 % lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.

  12. Systems biology elucidates common pathogenic mechanisms between nonalcoholic and alcoholic-fatty liver disease.

    Directory of Open Access Journals (Sweden)

    Silvia Sookoian

    Full Text Available The abnormal accumulation of fat in the liver is often related either to metabolic risk factors associated with metabolic syndrome in the absence of alcohol consumption (nonalcoholic fatty liver disease, NAFLD or to chronic alcohol consumption (alcoholic fatty liver disease, AFLD. Clinical and histological studies suggest that NAFLD and AFLD share pathogenic mechanisms. Nevertheless, current data are still inconclusive as to whether the underlying biological process and disease pathways of NAFLD and AFLD are alike. Our primary aim was to integrate omics and physiological data to answer the question of whether NAFLD and AFLD share molecular processes that lead to disease development. We also explored the extent to which insulin resistance (IR is a distinctive feature of NAFLD. To answer these questions, we used systems biology approaches, such as gene enrichment analysis, protein-protein interaction networks, and gene prioritization, based on multi-level data extracted by computational data mining. We observed that the leading disease pathways associated with NAFLD did not significantly differ from those of AFLD. However, systems biology revealed the importance of each molecular process behind each of the two diseases, and dissected distinctive molecular NAFLD and AFLD-signatures. Comparative co-analysis of NAFLD and AFLD clarified the participation of NAFLD, but not AFLD, in cardiovascular disease, and showed that insulin signaling is impaired in fatty liver regardless of the noxa, but the putative regulatory mechanisms associated with NAFLD seem to encompass a complex network of genes and proteins, plausible of epigenetic modifications. Gene prioritization showed a cancer-related functional map that suggests that the fatty transformation of the liver tissue is regardless of the cause, an emerging mechanism of ubiquitous oncogenic activation. In conclusion, similar underlying disease mechanisms lead to NAFLD and AFLD, but specific ones depict a

  13. Quantum information and the problem of mechanisms of biological evolution.

    Science.gov (United States)

    Melkikh, Alexey V

    2014-01-01

    One of the most important conditions for replication in early evolution is the de facto elimination of the conformational degrees of freedom of the replicators, the mechanisms of which remain unclear. In addition, realistic evolutionary timescales can be established based only on partially directed evolution, further complicating this issue. A division of the various evolutionary theories into two classes has been proposed based on the presence or absence of a priori information about the evolving system. A priori information plays a key role in solving problems in evolution. Here, a model of partially directed evolution, based on the learning automata theory, which includes a priori information about the fitness space, is proposed. A potential repository of such prior information is the states of biologically important molecules. Thus, the need for extended evolutionary synthesis is discussed. Experiments to test the hypothesis of partially directed evolution are proposed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  14. Can We Describe Biological Systems with Quantum Mechanics?

    International Nuclear Information System (INIS)

    Granados-Ramírez, C G; Benítez-Cardoza, C G; Carbajal-Tinoco, M D

    2016-01-01

    Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, including biological molecules. Due to numerous difficulties, however, it is necessary to introduce a series of approximations to overcome such impediments. We present a coarse-grained model of circular dichroism (CD) that is based on the theory of optical activity, developed by DeVoe, in order to predict CD spectra. In first stage, we determine the polarisability of individual monomers (residues, in the case of peptides) from experiments of molar absorptivity. The complex polarisabilities are used together with peptide structures obtained by density functional theory and other methods to determine their corresponding CD spectra, which are in reasonable agreement with their experimental counterparts. (paper)

  15. Effects of Ionizing Radiation on Biological Molecules—Mechanisms of Damage and Emerging Methods of Detection

    Science.gov (United States)

    Reisz, Julie A.; Bansal, Nidhi; Qian, Jiang; Zhao, Weiling

    2014-01-01

    Abstract Significance: The detrimental effects of ionizing radiation (IR) involve a highly orchestrated series of events that are amplified by endogenous signaling and culminating in oxidative damage to DNA, lipids, proteins, and many metabolites. Despite the global impact of IR, the molecular mechanisms underlying tissue damage reveal that many biomolecules are chemoselectively modified by IR. Recent Advances: The development of high-throughput “omics” technologies for mapping DNA and protein modifications have revolutionized the study of IR effects on biological systems. Studies in cells, tissues, and biological fluids are used to identify molecular features or biomarkers of IR exposure and response and the molecular mechanisms that regulate their expression or synthesis. Critical Issues: In this review, chemical mechanisms are described for IR-induced modifications of biomolecules along with methods for their detection. Included with the detection methods are crucial experimental considerations and caveats for their use. Additional factors critical to the cellular response to radiation, including alterations in protein expression, metabolomics, and epigenetic factors, are also discussed. Future Directions: Throughout the review, the synergy of combined “omics” technologies such as genomics and epigenomics, proteomics, and metabolomics is highlighted. These are anticipated to lead to new hypotheses to understand IR effects on biological systems and improve IR-based therapies. Antioxid. Redox Signal. 21: 260–292. PMID:24382094

  16. Improvement of mechanical and biological properties of Polycaprolactone loaded with Hydroxyapatite and Halloysite nanotubes.

    Science.gov (United States)

    Torres, E; Fombuena, V; Vallés-Lluch, A; Ellingham, T

    2017-06-01

    Hydroxyapatite (HA) and Halloysite nanotubes (HNTs) percentages have been optimized in Polycaprolactone (PCL) polymeric matrices to improve mechanical, thermal and biological properties of the composites, thus, to be applied in bone tissue engineering or as fixation plates. Addition of HA guarantees a proper compatibility with human bone due to its osteoconductive and osteoinductive properties, facilitating bone regeneration in tissue engineering applications. Addition of HNTs ensures the presence of tubular structures for subsequent drug loading in their lumen, of molecules such as curcumin, acting as controlled drug delivery systems. The addition of 20% of HA and different amounts of HNTs leads to a substantial improvement in mechanical properties with values of flexural strength up to 40% over raw PCL, with an increase in degradation temperature. DMA analyses showed stability in mechanical and thermal properties, having as a result a potential composite to be used as tissue engineering scaffold or resorbable fixation plate. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Mechanisms of sound seattering by biological targets and their aggregates

    Directory of Open Access Journals (Sweden)

    Natalia Gorska

    2006-03-01

    Full Text Available Natalia Gorska's thesis is based on a set of 9 papers published in scientific journals (Gorska & Klusek 1998, Gorska 2000, Gorska & Chu 2001a, b, Gorska & Ona 2003a, b and conference proceedings (Gorska & Klusek 1994, Gorska 1999, Gorska & Chu 2000, which broadly summarise her integrated research achievements in underwater acoustics from 1994 to 2003. She is the sole author of two of the articles (Gorska 1999, 2000, and is the first co-author, taking a leading part, in the others (Gorska & Klusek 1994, 1998, Gorska & Chu 2000, Gorska & Chu 200la, b, Gorska & Ona 2003a, b.     Her research objective was to work out the theoretical background to certain problems of sound scattering by biological targets - single individuals and aggregated layers of fish and zooplankton - in relation to environmental conditions in the sea. In the study she focused on acoustical extinction and backscattering, including the phenomenon of echo interference. In conjunction wit h the co-authors of papers Gorska & Ona 2003a, b, Gorska & Chu 2001a, b and Gorska & Chu 2000, she was able to apply and verify her theoretical results empirically.

  18. Chemical, mechanical and biological properties of contemporary composite surface sealers.

    Science.gov (United States)

    Anagnostou, Maria; Mountouris, George; Silikas, Nick; Kletsas, Dimitris; Eliades, George

    2015-12-01

    To evaluate the chemical, mechanical, and biological properties of modern composite surface sealers (CSS) having different compositions. The CSS products tested were Biscover LV (BC), Durafinish (DF), G-Coat Plus (GC), and Permaseal (PS). The tests performed were: (A): degree of conversion (DC%) by ATR-FTIR spectroscopy; (B): thickness of O2-inhibition layer by transmission optical microscopy; (C): surface hardness, 10 min after irradiation and following 1 week water storage, employing a Vickers indenter (VHN); (D): color (ΔE*) and gloss changes (ΔGU) after toothbrush abrasion, using L*a*b* colorimetry and glossimetry; (E): accelerated wear (GC,PS only) by an OHSU wear simulator plus 3D profilometric analysis, and (F): cytotoxicity testing of aqueous CSS eluents on human gingival fibroblast cultures employing the methyl-(3)H thymidine DNA labeling method. Statistical analyses included 1-way (A, B, ΔE*, ΔGU) and 2-way (C, F) ANOVAs, plus Tukey post hoc tests. Student's t-test was used to evaluate the results of the accelerated wear test (α=0.05 for all). The rankings of the statistical significant differences were: (A) PS (64.9)>DF,BC,GC (56.1-53.9) DC%; (B) DF,PS (12.3,9.8)>GC,BC (5.2,4.8) μm; (C): GC (37.6)>BC,DF (32.6,31.1)>PS (26.6) VHN (10 min/dry) and BC,DF (29.3,28.7)>GC(26.5)>PS(21.6) VHN (1w/water), with no significant material/storage condition interaction; (D): no differences were found among GC,DF,BC,PS (0.67-1.11) ΔE*, with all values within the visually acceptable range and PS,BC (32.8,29.4)>GC,DF (19.4,12.9) ΔGU; (E): no differences were found between GC and PS in volume loss (0.10,0.11 mm(3)), maximum (113.9,130.5 μm) and mean wear depths (30.3,27.5 μm); (F): at 1% v/v concentration, DF showed toxicity (23% vital cells vs 95-102% for others). However, at 5% v/v concentration DF (0%) and BC (9%) were the most toxic, whereas GC (58%) and PS (56%) showed moderate toxicity. Important chemical, mechanical, and biological properties exist among

  19. Biological mechanisms of radiation effects; Biologische Mechanismen der Strahlenwirkung

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, S.; Doerr, W. [Medizinische Universitaet Wien, ATRAB - Angewandte und Translationale Radiobiologie, Univ.-Klinik fuer Strahlentherapie, Wien (Austria)

    2017-07-15

    Exposure to ionizing radiation for diagnostic purposes is inevitable in modern medicine. The therapeutic application of irradiation is highly effective against cancer; however, this implies exposure of normal tissue structures to significant doses of radiation. Diagnostic or therapeutic exposure to ionizing radiation can result in tissue changes and tumor induction in the long term. Knowledge of the biological mechanisms underlying these effects is essential for individualization of the application. This article examines the biological mechanisms at the tissue and molecular level, the clinical manifestation of radiation effects, dose-dependence of the risk and the temporal progression as well as influencing factors. The time course of the reaction of tissues to radiation exposure extends over wide ranges up to many decades. The effects of radiation on tissues are classified into early and late and their pathobiology is significantly different. Various factors (R) influencing the clinical manifestation of radiation effects have been identified related to the exposure pattern. The radiation tolerance of normal tissue structures regarding the induction of functional deficits shows great variation but always has a threshold value, which is usually not exceeded in diagnostic procedures. The risk of a radiation-induced fatal malignancy (total body exposure 5%/Gy) for a medical administration of radiation must be considered as very low in comparison to the natural risks. Informed consent of patients must reflect this in a balanced way. (orig.) [German] Eine Exposition mit ionisierender Strahlung fuer diagnostische Zwecke ist in der modernen Medizin unumgaenglich. Bei einer Tumorerkrankung ist die therapeutische Anwendung dieser Strahlung hoch effektiv. Dies impliziert immer eine Exposition normaler Gewebestrukturen mit signifikanten Strahlendosen. Die diagnostische oder therapeutische Exposition mit ionisierender Strahlung kann langfristig zu Gewebeveraenderungen und

  20. Biology and Mechanics of Blood Flows Part II: Mechanics and Medical Aspects

    CERN Document Server

    Thiriet, Marc

    2008-01-01

    Biology and Mechanics of Blood Flows presents the basic knowledge and state-of-the-art techniques necessary to carry out investigations of the cardiovascular system using modeling and simulation. Part II of this two-volume sequence, Mechanics and Medical Aspects, refers to the extraction of input data at the macroscopic scale for modeling the cardiovascular system, and complements Part I, which focuses on nanoscopic and microscopic components and processes. This volume contains chapters on anatomy, physiology, continuum mechanics, as well as pathological changes in the vasculature walls including the heart and their treatments. Methods of numerical simulations are given and illustrated in particular by application to wall diseases. This authoritative book will appeal to any biologist, chemist, physicist, or applied mathematician interested in the functioning of the cardiovascular system.

  1. Mass balance to assess the efficiency of a mechanical-biological treatment

    International Nuclear Information System (INIS)

    Araujo Morais, J. de; Ducom, G.; Achour, F.; Rouez, M.; Bayard, R.

    2008-01-01

    Using mechanical-biological treatment of residual municipal solid waste, it is possible to significantly lower landfill volume and gas and leachate emissions. Moreover, the landfill characteristics are improved. The performance of the Mende (France) mechanical-biological treatment plant is assessed via mass balances coupled with manual sorting according to the MODECOM TM methodology and biochemical methane potential after 90 days of incubation. The site includes mechanical sorting operations, a rotary sequential bioreactor, controlled aerobic stabilisation corridors, maturation platforms, and a sanitary landfill site for waste disposal in separated cells. Results showed that several steps could be improved: after a first sieving step, about 12% of the potentially biodegradable matter is landfilled directly without any treatment; mechanical disintegration of papers and cardboards in the rotary sequential bioreactor is insufficient and leads to a high proportion of papers and cardboards being landfilled without further treatment. Two fine fractions go through stabilisation and maturation steps. At the end of the maturation step, about 54% of the potentially biodegradable matter is degraded. The biochemical methane potential after 90 days of incubation is reduced by 81% for one of the two fine fractions and reduced by 88% for the other one. Considering the whole plant, there is a reduction of nearly 20% DM of the entering residual municipal solid waste

  2. Mechanism of biological liquid superlubricity of Brasenia schreberi mucilage.

    Science.gov (United States)

    Liu, Pengxiao; Liu, Yuhong; Yang, Ye; Chen, Zhe; Li, Jinjin; Luo, Jianbin

    2014-04-08

    In the present work, an excellent biological lubricant extracted from an aquatic plant called Brasenia schreberi (B.s) is reported. With a rotary cylinder-on-ring tribometer, the lubrication properties of the B.s mucilage between quartz glass surfaces have been investigated under different rotation velocity, and an ultralow friction coefficient between 0.004 and 0.006 is obtained. It is observed that the ultralow friction coefficient is independent of the rotation speed, when it is less than 0.1 m/s. SEM images indicate that the mucilage surrounding B.s is composed of polysaccharide gels with a layered structure, which are called nanosheets in the following work. Moreover, it can be deduced that the liquid superlubricity is closely related to the B.s mucilage layer absorbed on the quartz glass surface by hydrogen bonds and the superlubricity behavior only occurs when the adsorption layer stably forms between the quartz glass surface and the B.s mucilage. It is also found that superlubricity is closely dependent upon the sheet structure of the B.s mucilage and water molecules in the mucilage. According to these results, a layered nanosheets lubrication mechanism has been revealed, i.e., the ultralow friction coefficient is due to the adsorption layer of polysaccharide on the quartz glass surface and the hydration layers of water molecules bonded on the polysaccharide nanosheets between the sliding surfaces.

  3. Physicochemical Mechanisms of Synergistic Biological Action of Combinations of Aromatic Heterocyclic Compounds

    OpenAIRE

    Evstigneev, Maxim P.

    2013-01-01

    The mechanisms of synergistic biological effects observed in the simultaneous use of aromatic heterocyclic compounds in combination are reviewed, and the specific biological role of heteroassociation of aromatic molecules is discussed.

  4. Mechanical and thermo-mechanical response of a lead-core bearing device subjected to different loading conditions

    Directory of Open Access Journals (Sweden)

    Zhelyazov Todor

    2018-01-01

    Full Text Available The contribution is focused on the numerical modelling, simulation and analysis of a lead-core bearing device for passive seismic isolation. An accurate finite element model of a lead-core bearing device is presented. The model is designed to analyse both mechanical and thermo-mechanical responses of the seismic isolator to different loading conditions. Specifically, the mechanical behaviour in a typical identification test is simulated. The response of the lead-core bearing device to circular sinusoidal paths is analysed. The obtained shear displacement – shear force relationship is compared to experimental data found in literature sources. The hypothesis that heating of the lead-core during cyclic loading affects the degrading phenomena in the bearing device is taken into account. Constitutive laws are defined for each material: lead, rubber and steel. Both predefined constitutive laws (in the used general–purpose finite element code and semi-analytical procedures aimed at a more accurate modelling of the constitutive relations are tested. The results obtained by finite element analysis are to be further used to calibrate a macroscopic model of the lead-core bearing device seen as a single-degree-of-freedom mechanical system.

  5. A Postulated Mechanism That Leads to Materialization and Dematerialization of Matter and to Antigravity.

    Science.gov (United States)

    Bearden, Thomas E.

    This document presents a discussion of the postulated mechanism that leads to the materialization and dematerialization of matter and to antigravity. The mechanism also explains why an orbital electron does not radiate energy, in contradiction to classical electromagnetic theory. One of the paradoxes of special relativity is explained. A new model…

  6. Lead inhibition of DNA-binding mechanism of Cys(2)His(2) zinc finger proteins.

    Science.gov (United States)

    Hanas, J S; Rodgers, J S; Bantle, J A; Cheng, Y G

    1999-11-01

    The association of lead with chromatin in cells suggests that deleterious metal effects may in part be mediated through alterations in gene function. To elucidate if and how lead may alter DNA binding of cysteine-rich zinc finger proteins, lead ions were analyzed for their ability to alter the DNA binding mechanism of the Cys(2)His(2) zinc finger protein transcription factor IIIA (TFIIIA). As assayed by DNase I protection, the interaction of TFIIIA with the 50-bp internal control region of the 5S ribosomal gene was partially inhibited by 5 microM lead ions and completely inhibited by 10 to 20 microM lead ions. Preincubation of free TFIIIA with lead resulted in DNA-binding inhibition, whereas preincubation of a TFIIIA/5S RNA complex with lead did not result in DNA-binding inhibition. Because 5S RNA binds TFIIIA zinc fingers, this result is consistent with an inhibition mechanism via lead binding to zinc fingers. The complete loss of DNase I protection on the 5S gene indicates the mechanism of inhibition minimally involves the N-terminal fingers of TFIIIA. Inhibition was not readily reversible and occurred in the presence of an excess of beta-mercaptoethanol. Inhibition kinetics were fast, progressing to completion in approximately 5 min. Millimolar concentrations of sulfhydryl-specific arsenic ions were not inhibitory for TFIIIA binding. Micromolar concentrations of lead inhibited DNA binding by Sp1, another Cys(2)His(2) finger protein, but not by the nonfinger protein AP2. Inhibition of Cys(2)His(2) zinc finger transcription factors by lead ions at concentrations near those known to have deleterious physiological effects points to new molecular mechanisms for lead toxicity in promoting disease.

  7. The potential biological mechanisms of arsenic-induced diabetes mellitus

    International Nuclear Information System (INIS)

    Tseng, C.-H.

    2004-01-01

    Although epidemiologic studies carried out in Taiwan, Bangladesh, and Sweden have demonstrated a diabetogenic effect of arsenic, the mechanisms remain unclear and require further investigation. This paper reviewed the potential biological mechanisms of arsenic-induced diabetes mellitus based on the current knowledge of the biochemical properties of arsenic. Arsenate can substitute phosphate in the formation of adenosine triphosphate (ATP) and other phosphate intermediates involved in glucose metabolism, which could theoretically slow down the normal metabolism of glucose, interrupt the production of energy, and interfere with the ATP-dependent insulin secretion. However, the concentration of arsenate required for such reaction is high and not physiologically relevant, and these effects may only happen in acute intoxication and may not be effective in subjects chronically exposed to low-dose arsenic. On the other hand, arsenite has high affinity for sulfhydryl groups and thus can form covalent bonds with the disulfide bridges in the molecules of insulin, insulin receptors, glucose transporters (GLUTs), and enzymes involved in glucose metabolism (e.g., pyruvate dehydrogenase and α-ketoglutarate dehydrogenase). As a result, the normal functions of these molecules can be hampered. However, a direct effect on these molecules caused by arsenite at physiologically relevant concentrations seems unlikely. Recent evidence has shown that treatment of arsenite at lower and physiologically relevant concentrations can stimulate glucose transport, in contrary to an inhibitory effect exerted by phenylarsine oxide (PAO) or by higher doses of arsenite. Induction of oxidative stress and interferences in signal transduction or gene expression by arsenic or by its methylated metabolites are the most possible causes to arsenic-induced diabetes mellitus through mechanisms of induction of insulin resistance and β cell dysfunction. Recent studies have shown that, in subjects with chronic

  8. Lead exposures and biological responses in military weapons systems: Aerosol characteristics and acute lead effects among US Army artillerymen: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, M.H.; Stebbings, J.H.; Peterson, D.P.; Johnson, S.A.; Kumar, R.; Goun, B.D.; Janssen, I.; Trier, J.E.

    1993-03-01

    This study was to determine the concentration and chemical nature of lead (Pb) aerosols produced during the firing of artillery and to determine the exposures and biological responses of crew members exposed to lead aerosols during such firing. The concentrations of lead-containing aerosols at crew positions depended on wind conditions, with higher concentrations when firing into a head wind. Aerosol concentrations were highest in the muzzle blast zone. Concentrations of lead in the blood of crew members rose during the first 12 days of exposure to elevated airborne lead concentrations and then leveled off. There was no rapid decrease in blood lead concentrations after completion of firing. Small decreases in hematocrit and small increases in free erythrocyte porphyrin were correlated with increasing exposure to airborne lead. These changes were reversed by seven weeks after firing. Changes in nerve conduction velocity had borderline statistical significance to airborne lead exposure. In measuring nerve conduction velocity, differences in skin temperature must be taken into account.

  9. Biological conversion of anglesite (PbSO(4)) and lead waste from spent car batteries to galena (PbS).

    Science.gov (United States)

    Weijma, Jan; De Hoop, Klaas; Bosma, Wobby; Dijkman, Henk

    2002-01-01

    Lead paste, a solid mixture containing PbSO(4), PbO(2), PbO/Pb(OH)(2) precipitate, and elemental Pb, is one of the main waste fractions from spent car batteries. Biological sulfidation represents a new process for recovery of lead from this waste. In this process the lead salts in lead paste are converted to galena (PbS) by sulfate-reducing bacteria. This paper investigates a continuous process for sulfidation of anglesite (PbSO(4)), the main constituent of lead paste, and lead paste, consisting of a laboratory-scale gas-lift bioreactor to which a slurry of anglesite or lead paste was supplied. Sulfate or elemental sulfur was added as an additional sulfur source. Hydrogen gas served as an electron donor for the biological reduction of sulfate and elemental sulfur to sulfide by sulfate- and sulfur-reducing bacteria. Anglesite was almost completely converted to galena at a loading rate of 19 kg of PbSO(4) m(-)(3) day(-)(1), producing a sludge of which the crystalline lead phases consisted of >98% PbS (galena) and 1-2% elemental Pb. With lead paste, stable sulfidation rates of up to 17 kg of lead paste m(-)(3) day(-)(1) were demonstrated, producing a sludge of which the crystalline lead phases consisted of an estimated >96% PbS, 1-2% elemental Pb, and 1-2% PbO(2).

  10. The biological basis of treating jaw discrepancies: An interplay of mechanical forces and skeletal configuration.

    Science.gov (United States)

    Karamesinis, Konstantinos; Basdra, Efthimia K

    2018-05-01

    Jaw discrepancies and malrelations affect a large proportion of the general population and their treatment is of utmost significance for individuals' health and quality of life. The aim of their therapy is the modification of aberrant jaw development mainly by targeting the growth potential of the mandibular condyle through its cartilage, and the architectural shape of alveolar bone through a suture type of structure, the periodontal ligament. This targeted treatment is achieved via external mechanical force application by using a wide variety of intraoral and extraoral appliances. Condylar cartilage and sutures exhibit a remarkable plasticity due to the mechano-responsiveness of the chondrocytes and the multipotent mesenchymal cells of the sutures. The tissues respond biologically and adapt to mechanical force application by a variety of signaling pathways and a final interplay between the proliferative activity and the differentiation status of the cells involved. These targeted therapeutic functional alterations within temporo-mandibular joint ultimately result in the enhancement or restriction of mandibular growth, while within the periodontal ligament lead to bone remodeling and change of its architectural structure. Depending on the form of the malrelation presented, the above treatment approaches, in conjunction or separately, lead to the total correction of jaw discrepancies and the achievement of facial harmony and function. Overall, the treatment of craniofacial and jaw anomalies can be seen as an interplay of mechanical forces and adaptations occurring within temporo-mandibular joint and alveolar bone. The aim of the present review is to present up-to-date knowledge on the mechano-biology behind jaw growth modification and alveolar bone remodeling. Furthermore, future molecular targeted therapeutic strategies are discussed aiming at the improvement of mechanically-driven chondrogenesis and osteogenesis. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. A proposed chemical mechanism for biological phosphate removal ...

    African Journals Online (AJOL)

    This paper presents an alternative for the ";all biological"; phosphate removal model. It is postulated that a chemical substance in wastewater reacts with orthophosphate under anaerobic conditions to make the so-called luxury uptake of phosphorus possible in biological nutrient removal (BNR) activated sludge plants.

  12. Beyond the therapeutic shackles of the monoamines: New mechanisms in bipolar disorder biology.

    Science.gov (United States)

    Data-Franco, João; Singh, Ajeet; Popovic, Dina; Ashton, Melanie; Berk, Michael; Vieta, Eduard; Figueira, M L; Dean, Olivia M

    2017-01-04

    Multiple novel biological mechanisms putatively involved in the etiology of bipolar disorders are being explored. These include oxidative stress, altered glutamatergic neurotransmission, mitochondrial dysfunction, inflammation, cell signaling, apoptosis and impaired neurogenesis. Important clinical translational potential exists for such mechanisms to help underpin development of novel therapeutics - much needed given limitations of current therapies. These new mechanisms also help improve our understanding of how current therapeutics might exert their effects. Lithium, for example, appears to have antioxidant, immunomodulatory, signaling, anti-apoptotic and neuroprotective properties. Similar properties have been attributed to other mood stabilizers such as valproate, lamotrigine, and quetiapine. Perhaps of greatest translational value has been the recognition of such mechanisms leading to the emergence of novel therapeutics for bipolar disorders. These include the antioxidant N-acetylcysteine, the anti-inflammatory celecoxib, and ketamine - with effects on the glutamatergic system and microglial inhibition. We review these novel mechanisms and emerging therapeutics, and comment on next steps in this space. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Mechanical and fatigue properties of martensitic Fe-13Cr steel in contact with lead and lead-bismuth melts

    Energy Technology Data Exchange (ETDEWEB)

    Yaskiv, O.I., E-mail: oleh.yaskiv@ipm.lviv.ua; Fedirko, V.M.

    2014-01-15

    Highlights: •We investigated the influence of Pb and Pb-Bi melts on mechanical properties of Fe-13Cr steel at high temperatures. •We revealed the temperature interval of liquid metal embrittlement of Fe-13Cr steel. •Pb-Bi has more negative impact as compared with Pb for both plasticity and fatigue. -- Abstract: The influence of stagnant liquid-metal environments (Pb and Pb-Bi) on mechanical (strength and plasticity) and fatigue properties (low cycle fatigue) of martensitic Fe-13Cr steel in temperature interval of 250–600 °S have been investigated. Heavy liquid metals facilitate decreasing in ultimate strength by 10–20% against that in vacuum. The increase of temperature enhances this effect. Fe-13Cr steel is susceptible to liquid-metal embrittlement in the temperature interval of 350–450 °S, which manifests itself more substantially in lead-bismuth eutectic. The decrease of plasticity in Pb is 11% at 450 °S and in Pb-Bi is 30% in temperature interval 350–400 °S. Liquid metal environments significantly reduce fatigue life of Fe-13Cr steel. Pb-Bi has a more negative impact. In particular, with increasing total strain amplitude (up to 1.0%), the decrease in the cycle number to fracture by more than two orders of magnitude occurs.

  14. Biological agents and respiratory infections: Causative mechanisms and practice management.

    Science.gov (United States)

    Takayanagi, Noboru

    2015-09-01

    Biological agents are increasingly being used to treat patients with immune-mediated inflammatory disease. In Japan, currently approved biological agents for patients with rheumatoid arthritis (RA) include tumor necrosis factor inhibitors, interleukin-6 receptor-blocking monoclonal antibody, and T-cell costimulation inhibitor. Rheumatologists have recognized that safety issues are critical aspects of treatment decisions in RA. Therefore, a wealth of safety data has been gathered from a number of sources, including randomized clinical trials and postmarketing data from large national registries. These data revealed that the most serious adverse events from these drugs are respiratory infections, especially pneumonia, tuberculosis, nontuberculous mycobacteriosis, and Pneumocystis jirovecii pneumonia, and that the most common risk factors associated with these respiratory infections are older age, concomitant corticosteroid use, and underlying respiratory comorbidities. Because of this background, in 2014, the Japanese Respiratory Society published their consensus statement of biological agents and respiratory disorders. This review summarizes this statement and adds recent evidence, especially concerning respiratory infections in RA patients, biological agents and respiratory infections, and practice management of respiratory infections in patients treated with biological agents. To decrease the incidence of infections and reduce mortality, we should know the epidemiology, risk factors, management, and methods of prevention of respiratory infections in patients receiving biological agents. Copyright © 2015 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

  15. Mechanical performances of lead-free solder joint connections with applications in the aerospace domain

    Directory of Open Access Journals (Sweden)

    Georgiana PADURARU

    2016-03-01

    Full Text Available The paper presents some theoretical and experimental aspects regarding the tribological performances of lead-free solder joint connections, with application in the aerospace domain. In order to highlight the mechanical and tribological properties of solder joint in correlation with different pad finishes, there were made some mechanical determinations using a dedicated Share Test System. The theoretical model highlights the link between the experimental results and the influence of gravitational acceleration on the mechanical and functional integrity of the electronic assemblies that works in vibration environment. The paper novelty is provided by the interdisciplinary experiment that offers results that can be used in the mechanical, tribological, electronical and aerospace domains.

  16. Laboratory results of some biological measures in workers exposed to lead

    Energy Technology Data Exchange (ETDEWEB)

    Secchi, G.C.; Alessio, L.

    1974-12-01

    Erthrocyte ALA-dehydratase (ALAD) activity and blood lead values were studied in different groups of subjects not occupationally exposed to lead and compared with values for exposed workers. The results lead to the conclusion that measurement of ALAD activity is more useful in evaluating possible exposure of general population groups to minimal quantities of lead than in the surveillance of workers in the lead industries.

  17. Mechanical properties of the beetle elytron, a biological composite material

    Science.gov (United States)

    We determined the relationship between composition and mechanical properties of elytral (modified forewing) cuticle of the beetles Tribolium castaneum and Tenebrio molitor. Elytra of both species have similar mechanical properties at comparable stages of maturation (tanning). Shortly after adult ecl...

  18. Microstructure And Mechanical Properties Of Lead Oxide- Thermoplastic Elas Tomer Composite

    International Nuclear Information System (INIS)

    Sudirman; Handayani, Ari; Darwinto, Tri; Teguh, Yulius S.P.P.; Sunarni, Anik; Marlijanti, Isni

    2000-01-01

    Research on microstructure and mechanical properties of lead oxide-thermoplastic elastomer composite with Pb 3 O 4 as lead oxide. Thermoplastic elastomer synthesized from natural rubber as the elastomer and methyl metacrilate as the thermoplastic and irradiated simultaneously with optimum gamma ray. Thermoplastic elastomer (NR-PMMA) grind in a laboplastomill and Pb 3 O 4 was added in varied amount of 10%. 30%. 40% and 50%wt.The results showed that mechanical properties (tensile strength and elongation break) decreased as the Pb 3 O 4 composition increased. Microstructure from SEM observation showed that Pb 3 O 4 distributed evenly and having function as filler in composite

  19. Uncovering the underlying physical mechanisms of biological systems via quantification of landscape and flux

    International Nuclear Information System (INIS)

    Xu Li; Chu Xiakun; Yan Zhiqiang; Zheng Xiliang; Zhang Kun; Zhang Feng; Yan Han; Wu Wei; Wang Jin

    2016-01-01

    In this review, we explore the physical mechanisms of biological processes such as protein folding and recognition, ligand binding, and systems biology, including cell cycle, stem cell, cancer, evolution, ecology, and neural networks. Our approach is based on the landscape and flux theory for nonequilibrium dynamical systems. This theory provides a unifying principle and foundation for investigating the underlying mechanisms and physical quantification of biological systems. (topical review)

  20. Fracture Mechanics Analyses of the Slip-Side Joggle Regions of Wing-Leading-Edge Panels

    Science.gov (United States)

    Raju, Ivatury S.; Knight, Norman F., Jr.; Song, Kyongchan; Phillips, Dawn R.

    2011-01-01

    The Space Shuttle wing-leading edge consists of panels that are made of reinforced carbon-carbon. Coating spallation was observed near the slip-side region of the panels that experience extreme heating. To understand this phenomenon, a root-cause investigation was conducted. As part of that investigation, fracture mechanics analyses of the slip-side joggle regions of the hot panels were conducted. This paper presents an overview of the fracture mechanics analyses.

  1. Including a Service Learning Educational Research Project in a Biology Course-I: Assessing Community Awareness of Childhood Lead Poisoning

    Science.gov (United States)

    Abu-Shakra, Amal; Saliim, Eric

    2012-01-01

    A university course project was developed and implemented in a biology course, focusing on environmental problems, to assess community awareness of childhood lead poisoning. A set of 385 questionnaires was generated and distributed in an urban community in North Carolina, USA. The completed questionnaires were sorted first into yes and no sets…

  2. Thermo-mechanical tests on W7-X current lead flanges

    International Nuclear Information System (INIS)

    Dhard, Chandra Prakash; Rummel, Thomas; Zacharias, Daniel; Bykov, Victor; Moennich, Thomas; Buscher, Klaus-Peter

    2013-01-01

    Highlights: • There are significant mechanical loads on the cryostat and radial flanges for W7-X current leads. • These are due to evacuation of W7-X cryostat, cool-down of cold mass, electro-magnetic forces and self weight of leads. • The actual mechanical loads were reduced to simplify the experimental set-up. • The tests were carried out on mock-up flanges test assembly at ambient temperature and at 77 K. • The thermo-mechanical tests on W7-X current lead flanges validate the design and joints of these flanges to the leads. -- Abstract: Fourteen pieces of high temperature superconducting current leads (CL) arranged in seven pairs, will be installed on the outer vessel of Wendelstein 7-X (W7-X) stellarator. In order to support the CL, it is provided with two glass fiber reinforce plastic (GFRP) flanges, namely, the lower cryostat flange (CF) remaining at room temperature and upper radial flange (RF) at about 5 K. Both the flanges i.e. CF and RF experience high mechanical loads with respect to the CL, due to the evacuation of W7-X cryostat, cool-down of cold mass including the CL, electro-magnetic forces due to current and plasma operations and self weight of CL. In order to check the integrity of these flanges for such mechanical loads, thermo-mechanical tests were carried out on these flanges at room temperatures and at liquid nitrogen (LN2) temperatures. The details of test set-up, results and modeling are described in the paper

  3. Deciphering complement mechanisms: The contributions of structural biology.

    NARCIS (Netherlands)

    Arlaud, G.J.; Barlow, P.N.; Gaboriaud, C.; Gros, P.; Narayana, S.V.L.

    2007-01-01

    Since the resolution of the first three-dimensional structure of a complement component in 1980, considerable efforts have been put into the investigation of this system through structural biology techniques, resulting in about a hundred structures deposited in the Protein Data Bank by the beginning

  4. Nanomechanical strength mechanisms of hierarchical biological materials and tissues.

    Science.gov (United States)

    Buehler, Markus J; Ackbarow, Theodor

    2008-12-01

    Biological protein materials (BPMs), intriguing hierarchical structures formed by assembly of chemical building blocks, are crucial for critical functions of life. The structural details of BPMs are fascinating: They represent a combination of universally found motifs such as alpha-helices or beta-sheets with highly adapted protein structures such as cytoskeletal networks or spider silk nanocomposites. BPMs combine properties like strength and robustness, self-healing ability, adaptability, changeability, evolvability and others into multi-functional materials at a level unmatched in synthetic materials. The ability to achieve these properties depends critically on the particular traits of these materials, first and foremost their hierarchical architecture and seamless integration of material and structure, from nano to macro. Here, we provide a brief review of this field and outline new research directions, along with a review of recent research results in the development of structure-property relationships of biological protein materials exemplified in a study of vimentin intermediate filaments.

  5. Behavioural evidence for separate mechanisms of audiovisual temporal binding as a function of leading sensory modality.

    Science.gov (United States)

    Cecere, Roberto; Gross, Joachim; Thut, Gregor

    2016-06-01

    The ability to integrate auditory and visual information is critical for effective perception and interaction with the environment, and is thought to be abnormal in some clinical populations. Several studies have investigated the time window over which audiovisual events are integrated, also called the temporal binding window, and revealed asymmetries depending on the order of audiovisual input (i.e. the leading sense). When judging audiovisual simultaneity, the binding window appears narrower and non-malleable for auditory-leading stimulus pairs and wider and trainable for visual-leading pairs. Here we specifically examined the level of independence of binding mechanisms when auditory-before-visual vs. visual-before-auditory input is bound. Three groups of healthy participants practiced audiovisual simultaneity detection with feedback, selectively training on auditory-leading stimulus pairs (group 1), visual-leading stimulus pairs (group 2) or both (group 3). Subsequently, we tested for learning transfer (crossover) from trained stimulus pairs to non-trained pairs with opposite audiovisual input. Our data confirmed the known asymmetry in size and trainability for auditory-visual vs. visual-auditory binding windows. More importantly, practicing one type of audiovisual integration (e.g. auditory-visual) did not affect the other type (e.g. visual-auditory), even if trainable by within-condition practice. Together, these results provide crucial evidence that audiovisual temporal binding for auditory-leading vs. visual-leading stimulus pairs are independent, possibly tapping into different circuits for audiovisual integration due to engagement of different multisensory sampling mechanisms depending on leading sense. Our results have implications for informing the study of multisensory interactions in healthy participants and clinical populations with dysfunctional multisensory integration. © 2016 The Authors. European Journal of Neuroscience published by Federation

  6. Urban gardens: Lead exposure, recontamination mechanisms, and implications for remediation design

    International Nuclear Information System (INIS)

    Clark, Heather F.; Hausladen, Debra M.; Brabander, Daniel J.

    2008-01-01

    Environmental lead contamination is prevalent in urban areas where soil represents a significant sink and pathway of exposure. This study characterizes the speciation of lead that is relevant to local recontamination and to human exposure in the backyard gardens of Roxbury and Dorchester, MA, USA. One hundred forty-one backyard gardens were tested by X-ray fluorescence, and 81% of gardens have lead levels above the US EPA action limit of 400 μg/g. Raised gardening beds are the in situ exposure reduction method used in the communities to promote urban gardening. Raised beds were tested for lead and the results showed that the lead concentration increased from an initial range of 150±40 μg/g to an average of 336 μg/g over 4 years. The percent distribution of lead in the fine grain soil (<100 μm) and the trace metal signature of the raised beds support the conclusion that the mechanism of recontamination is wind-transported particles. Scanning electron microscopy and sequential extraction were used to characterize the speciation of lead, and the trace metal signature of the fine grain soil in both gardens and raised gardening beds is characteristic of lead-based paint. This study demonstrates that raised beds are a limited exposure reduction method and require maintenance to achieve exposure reduction goals. An exposure model was developed based on a suite of parameters that combine relevant values from the literature with site-specific quantification of exposure pathways. This model suggests that consumption of homegrown produce accounts for only 3% of children's daily exposure of lead while ingestion of fine grained soil (<100 μm) accounts for 82% of the daily exposure. This study indicates that urban lead remediation on a yard-by-yard scale requires constant maintenance and that remediation may need to occur on a neighborhood-wide scale

  7. Diversity Generator Mechanisms Are Essential Components of Biological Systems: The Two Queen Hypothesis

    Directory of Open Access Journals (Sweden)

    Eric Muraille

    2018-02-01

    Full Text Available Diversity is widely known to fuel adaptation and evolutionary processes and increase robustness at the population, species and ecosystem levels. The Neo-Darwinian paradigm proposes that the diversity of biological entities is the consequence of genetic changes arising spontaneously and randomly, without regard for their usefulness. However, a growing body of evidence demonstrates that the evolutionary process has shaped mechanisms, such as horizontal gene transfer mechanisms, meiosis and the adaptive immune system, which has resulted in the regulated generation of diversity among populations. Though their origins are unrelated, these diversity generator (DG mechanisms share common functional properties. They (i contribute to the great unpredictability of the composition and/or behavior of biological systems, (ii favor robustness and collectivism among populations and (iii operate mainly by manipulating the systems that control the interaction of living beings with their environment. The definition proposed here for DGs is based on these properties and can be used to identify them according to function. Interestingly, prokaryotic DGs appear to be mainly reactive, as they generate diversity in response to environmental stress. They are involved in the widely described Red Queen/arms race/Cairnsian dynamic. The emergence of multicellular organisms harboring K selection traits (longer reproductive life cycle and smaller population size has led to the acquisition of a new class of DGs that act anticipatively to stress pressures and generate a distinct dynamic called the “White Queen” here. The existence of DGs leads to the view of evolution as a more “intelligent” and Lamarckian-like process. Their repeated selection during evolution could be a neglected example of convergent evolution and suggests that some parts of the evolutionary process are tightly constrained by ecological factors, such as the population size, the generation time and

  8. Introduction to the Symposium "Leading Students and Faculty to Quantitative Biology through Active Learning".

    Science.gov (United States)

    Waldrop, Lindsay D; Miller, Laura A

    2015-11-01

    The broad aim of this symposium and set of associated papers is to motivate the use of inquiry-based, active-learning teaching techniques in undergraduate quantitative biology courses. Practical information, resources, and ready-to-use classroom exercises relevant to physicists, mathematicians, biologists, and engineers are presented. These resources can be used to address the lack of preparation of college students in STEM fields entering the workforce by providing experience working on interdisciplinary and multidisciplinary problems in mathematical biology in a group setting. Such approaches can also indirectly help attract and retain under-represented students who benefit the most from "non-traditional" learning styles and strategies, including inquiry-based, collaborative, and active learning. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  9. Biological pathways and genetic mechanisms involved in social functioning.

    Science.gov (United States)

    Ordoñana, Juan R; Bartels, Meike; Boomsma, Dorret I; Cella, David; Mosing, Miriam; Oliveira, Joao R; Patrick, Donald L; Veenhoven, Ruut; Wagner, Gert G; Sprangers, Mirjam A G

    2013-08-01

    To describe the major findings in the literature regarding associations between biological and genetic factors and social functioning, paying special attention to: (1) heritability studies on social functioning and related concepts; (2) hypothesized biological pathways and genetic variants that could be involved in social functioning, and (3) the implications of these results for quality-of-life research. A search of Web of Science and PubMed databases was conducted using combinations of the following keywords: genetics, twins, heritability, social functioning, social adjustment, social interaction, and social dysfunction. Variability in the definitions and measures of social functioning was extensive. Moderate to high heritability was reported for social functioning and related concepts, including prosocial behavior, loneliness, and extraversion. Disorders characterized by impairments in social functioning also show substantial heritability. Genetic variants hypothesized to be involved in social functioning are related to the network of brain structures and processes that are known to affect social cognition and behavior. Better knowledge and understanding about the impact of genetic factors on social functioning is needed to help us to attain a more comprehensive view of health-related quality-of-life (HRQOL) and will ultimately enhance our ability to identify those patients who are vulnerable to poor social functioning.

  10. Cloning Yeast Actin cDNA Leads to an Investigative Approach for the Molecular Biology Laboratory

    Science.gov (United States)

    Black, Michael W.; Tuan, Alice; Jonasson, Erin

    2008-01-01

    The emergence of molecular tools in multiple disciplines has elevated the importance of undergraduate laboratory courses that train students in molecular biology techniques. Although it would also be desirable to provide students with opportunities to apply these techniques in an investigative manner, this is generally not possible in the…

  11. Biology and Medicine Division annual report, 1981-1982. [Lead abstract

    Energy Technology Data Exchange (ETDEWEB)

    1983-04-01

    Separate abstracts were prepared for the 61 research reports in the 1981-1982 annual report for the Biology and Medicine Division of the Lawrence Berkeley Laboratory. Programs reviewed include research medicine, Donner Pavilion, environmental physiology, radiation biophysics and structural biophysics. (KRM)

  12. THE ADVERSE OUTCOME PATHWAY (AOP) FRAMEWORK: A FRAMEWORK FOR ORGANIZING BIOLOGICAL KNOWLEDGE LEADING TO HEALTH RISKS.

    Science.gov (United States)

    An Adverse Outcome Pathway (AOP) represents the organization of current and newly acquired knowledge of biological pathways. These pathways contain a series of nodes (Key Events, KEs) that when sufficiently altered influence the next node on the pathway, beginning from an Molecul...

  13. Biological and medical research with accelerated heavy ions at the Bevalac, 1977-1980. [Lead abstract

    Energy Technology Data Exchange (ETDEWEB)

    Pirruccello, M.C.; Tobias, C.A. (eds.)

    1980-11-01

    Separate abstracts were prepared for the 46 papers presented in this progress report. This report is a major review of studies with accelerated heavy ions carried out by the Biology and Medicine Division of Lawrence Berkeley Laboratory from 1977 to 1980. (KRM)

  14. Fluctuating Nonlinear Spring Model of Mechanical Deformation of Biological Particles

    NARCIS (Netherlands)

    Kononova, Olga; Snijder, Joost; Kholodov, Yaroslav; Marx, Kenneth A; Wuite, Gijs J L; Roos, Wouter H; Barsegov, Valeri

    The mechanical properties of virus capsids correlate with local conformational dynamics in the capsid structure. They also reflect the required stability needed to withstand high internal pressures generated upon genome loading and contribute to the success of important events in viral infectivity,

  15. Biological evaluation of mechanical circulatory support systems in calves

    NARCIS (Netherlands)

    Rakhorst, G; VanDerMeer, J; Kik, C; Mihaylov, D; Havlik, P; Trinkl, J; Monties, [No Value

    Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two

  16. Understanding the biological mechanisms of Zika virus disease ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project will use advanced biomolecular, genomics and proteomics techniques to explain the molecular mechanisms by which the Zika virus infects and persists in the human body, how it affects the human reproductive and central nervous system, and how the risk of fetal abnormalities can be better predicted in infected ...

  17. A mechanism of leading-edge protrusion in the absence of Arp2/3 complex.

    Science.gov (United States)

    Suraneni, Praveen; Fogelson, Ben; Rubinstein, Boris; Noguera, Philippe; Volkmann, Niels; Hanein, Dorit; Mogilner, Alex; Li, Rong

    2015-03-01

    Cells employ protrusive leading edges to navigate and promote their migration in diverse physiological environments. Classical models of leading-edge protrusion rely on a treadmilling dendritic actin network that undergoes continuous assembly nucleated by the Arp2/3 complex, forming ruffling lamellipodia. Recent work demonstrated, however, that, in the absence of the Arp2/3 complex, fibroblast cells adopt a leading edge with filopodia-like protrusions (FLPs) and maintain an ability to move, albeit with altered responses to different environmental signals. We show that formin-family actin nucleators are required for the extension of FLPs but are insufficient to produce a continuous leading edge in fibroblasts lacking Arp2/3 complex. Myosin II is concentrated in arc-like regions of the leading edge in between FLPs, and its activity is required for coordinated advancement of these regions with formin-generated FLPs. We propose that actomyosin contraction acting against membrane tension advances the web of arcs between FLPs. Predictions of this model are verified experimentally. The dependence of myosin II in leading-edge advancement helps explain the previously reported defect in directional movement in the Arpc3-null fibroblasts. We provide further evidence that this defect is cell autonomous during chemotaxis. © 2015 Suraneni 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).

  18. Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging.

    Science.gov (United States)

    Serpell, Christopher J; Rutte, Reida N; Geraki, Kalotina; Pach, Elzbieta; Martincic, Markus; Kierkowicz, Magdalena; De Munari, Sonia; Wals, Kim; Raj, Ritu; Ballesteros, Belén; Tobias, Gerard; Anthony, Daniel C; Davis, Benjamin G

    2016-10-26

    The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular 'blueprint'; this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as 'contrast agents' if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging.

  19. Mechanization and Control Concepts for Biologically Inspired Micro Aerial Vehicles

    Science.gov (United States)

    Raney, David L.; Slominski, Eric C.

    2003-01-01

    It is possible that MAV designs of the future will exploit flapping flight in order to perform missions that require extreme agility, such as rapid flight beneath a forest canopy or within the confines of a building. Many of nature's most agile flyers generate flapping motions through resonant excitation of an aeroelastically tailored structure: muscle tissue is used to excite a vibratory mode of their flexible wing structure that creates propulsion and lift. A number of MAV concepts have been proposed that would operate in a similar fashion. This paper describes an ongoing research activity in which mechanization and control concepts with application to resonant flapping MAVs are being explored. Structural approaches, mechanical design, sensing and wingbeat control concepts inspired by hummingbirds, bats and insects are examined. Experimental results from a testbed capable of generating vibratory wingbeat patterns that approximately match those exhibited by hummingbirds in hover, cruise, and reverse flight are presented.

  20. Biological Mechanisms by Which Antiproliferative Actions of Resveratrol Are Minimized.

    Science.gov (United States)

    Ho, Yih; Lin, Yu-Syuan; Liu, Hsuan-Liang; Shih, Ya-Jung; Lin, Shin-Ying; Shih, Ai; Chin, Yu-Tang; Chen, Yi-Ru; Lin, Hung-Yun; Davis, Paul J

    2017-09-21

    Preclinical and clinical studies have offered evidence for protective effects of various polyphenol-rich foods against cardiovascular diseases, neurodegenerative diseases, and cancers. Resveratrol is among the most widely studied polyphenols. However, the preventive and treatment effectiveness of resveratrol in cancer remain controversial because of certain limitations in existing studies. For example, studies of the activity of resveratrol against cancer cell lines in vitro have often been conducted at concentrations in the low μM to mM range, whereas dietary resveratrol or resveratrol-containing wine rarely achieve nM concentrations in the clinic. While the mechanisms underlying the failure of resveratrol to inhibit cancer growth in the intact organism are not fully understood, the interference by thyroid hormones with the anticancer activity of resveratrol have been well documented in both in vitro and xenograft studies. Thus, endogenous thyroid hormones may explain the failure of anticancer actions of resveratrol in intact animals, or in the clinic. In this review, mechanisms involved in resveratrol-induced antiproliferation and effects of thyroid hormones on these mechanisms are discussed.

  1. The dark side of creativity: biological vulnerability and negative emotions lead to greater artistic creativity.

    Science.gov (United States)

    Akinola, Modupe; Mendes, Wendy Berry

    2008-12-01

    Historical and empirical data have linked artistic creativity to depression and other affective disorders. This study examined how vulnerability to experiencing negative affect, measured with biological products, and intense negative emotions influenced artistic creativity. The authors assessed participants' baseline levels of an adrenal steroid (dehydroepiandrosterone-sulfate, or DHEAS), previously linked to depression, as a measure of affective vulnerability. They then manipulated emotional responses by randomly assigning participants to receive social rejection or social approval or to a nonsocial situation. Participants then completed artistic collages, which were later evaluated by artists. Results confirmed a person-by-situation interaction. Social rejection was associated with greater artistic creativity; however, the interaction between affective vulnerability (lower baseline DHEAS) and condition was significant, suggesting that situational triggers of negative affect were especially influential among those lower in DHEAS, which resulted in the most creative products. These data provide evidence of possible biological and social pathways to artistic creativity.

  2. The Dark Side of Creativity: Biological Vulnerability and Negative Emotions Lead to Greater Artistic Creativity

    Science.gov (United States)

    Akinola, Modupe; Mendes, Wendy Berry

    2009-01-01

    Historical and empirical data have linked artistic creativity to depression and other affective disorders. This study examined how vulnerability to experiencing negative affect, measured with biological products, and intense negative emotions influenced artistic creativity. The authors assessed participants' baseline levels of an adrenal steroid (dehydroepiandrosterone-sulfate, or DHEAS), previously linked to depression, as a measure of affective vulnerability. They then manipulated emotional responses by randomly assigning participants to receive social rejection or social approval or to a nonsocial situation. Participants then completed artistic collages, which were later evaluated by artists. Results confirmed a person-by-situation interaction. Social rejection was associated with greater artistic creativity; however, the interaction between affective vulnerability (lower baseline DHEAS) and condition was significant, suggesting that situational triggers of negative affect were especially influential among those lower in DHEAS, which resulted in the most creative products. These data provide evidence of possible biological and social pathways to artistic creativity. PMID:18832338

  3. Electrolytic reduction of nitroheterocyclic drugs leads to biologically important damage in DNA

    International Nuclear Information System (INIS)

    Lafleur, M.V.M.; Pluijmackers-Westmijze, E.J.; Loman, H.

    1985-01-01

    The effects of electrolytic reduction of nitroimidazole drugs on biologically active DNA was studied. The results show that reduction of the drugs in the presence of DNA affects inactivation for both double-stranded (RF) and single-stranded phiX174 DNA. However, stable reduction products did not make a significant contribution to the lethal damage in DNA. This suggests that probably a short-lived intermediate of reduction of nitro-compounds is responsible for damage to DNA. (author)

  4. Neurodevelopmental consequences in offspring of mothers with preeclampsia during pregnancy: underlying biological mechanism via imprinting genes.

    Science.gov (United States)

    Nomura, Yoko; John, Rosalind M; Janssen, Anna Bugge; Davey, Charles; Finik, Jackie; Buthmann, Jessica; Glover, Vivette; Lambertini, Luca

    2017-06-01

    Preeclampsia is known to be a leading cause of mortality and morbidity among mothers and their infants. Approximately 3-8% of all pregnancies in the US are complicated by preeclampsia and another 5-7% by hypertensive symptoms. However, less is known about its long-term influence on infant neurobehavioral development. The current review attempts to demonstrate new evidence for imprinting gene dysregulation caused by hypertension, which may explain the link between maternal preeclampsia and neurocognitive dysregulation in offspring. Pub Med and Web of Science databases were searched using the terms "preeclampsia," "gestational hypertension," "imprinting genes," "imprinting dysregulation," and "epigenetic modification," in order to review the evidence demonstrating associations between preeclampsia and suboptimal child neurodevelopment, and suggest dysregulation of placental genomic imprinting as a potential underlying mechanism. The high mortality and morbidity among mothers and fetuses due to preeclampsia is well known, but there is little research on the long-term biological consequences of preeclampsia and resulting hypoxia on the fetal/child neurodevelopment. In the past decade, accumulating evidence from studies that transcend disciplinary boundaries have begun to show that imprinted genes expressed in the placenta might hold clues for a link between preeclampsia and impaired cognitive neurodevelopment. A sudden onset of maternal hypertension detected by the placenta may result in misguided biological programming of the fetus via changes in the epigenome, resulting in suboptimal infant development. Furthering our understanding of the molecular and cellular mechanisms through which neurodevelopmental trajectories of the fetus/infant are affected by preeclampsia and hypertension will represent an important first step toward preventing adverse neurodevelopment in infants.

  5. Energy implications of mechanical and mechanical-biological treatment compared to direct waste-to-energy.

    Science.gov (United States)

    Cimpan, Ciprian; Wenzel, Henrik

    2013-07-01

    Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical-biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJprimary/100 MJinput waste, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3-9.5%, 1-18% and 1-8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS-based system achieved the highest savings, on the condition of SRF co-combustion. As a sensitivity scenario, alternative utilisation of SRF in cement kilns was modelled. It supported similar or higher net savings for all pre-treatment systems compared to mass combustion WtE, except when WtE CHP was possible in the first two background energy scenarios. Recovery of plastics for recycling before energy recovery increased net energy savings in most scenario variations, over those of full

  6. Occupational exposure and biological evaluation of lead in Iranian workers-a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Kourosh Sayehmiri

    2016-09-01

    Full Text Available Introduction: Lead exposure is considered as a global health problem. The irreparable harmful effects of this heavy metal on human have been proven in various studies. Comparing to general population, workers in related industries are more exposed to lead. Several studies have investigated lead occupational exposure and its biological evaluation in Iran; however there is no overall estimate. Thus, the present study was conducted to determine the occupational exposure to lead and its biological evaluation in Iranian workers, using systematic review and meta-analysis. Material and Method: This study was carried out based on information obtained from databases including Magiran, Iranmedex, SID, Medlib, Trials Register, Scopus, Pubmed, Science Direct, Cochran, Embase, Medline, Web of Science, Springer, Online Library Wiley, and Google Scholar from 1991 to 2016, using standard key words. All of the reviewed papers which met the inclusion criteria have been evaluated. Data combination was performed according to Random Effects Model using Stata software version 11.1. Result: In the 34 qualified studies, the mean blood lead level (BLL concentration in Iranian workers was estimated 42.8µg/dl (95% CI: 35.15-50.49. The minimum and maximum BLL were belonged to west (28.348µg/dl and center (45.928µg/dl regions of Iran, respectively. Considering different occupations, the lowest mean value was reported in textile industry workers (12.3 µg/dl, while the highest value was for zinc-lead mine workers (72.6 µg/dl. Mean breathing air lead level of Iranian workers reported in 4 studies was estimated 0.23 mg/m3 (95% CI: 0.14-0.33. Conclusion: According to the high concentration of BLL and breathing air, it is recommended to increase protective measures and frequent screening. Scheduled clinical and paraclinical examination should also be performed for workers.

  7. Biological assessment of continuous exposure to tritium and lead in the rat

    International Nuclear Information System (INIS)

    Cahill, D.F.; Reiter, L.W.; Santolucito, J.A.; Rehnberg, G.I.; Ash, M.E.; Favor, M.J.; Bursian, S.J.; Wriht, J.F.; Laskey, J.W.

    1976-01-01

    A broad investigation of the effects of simultaneous exposure to two potentially synergistic environmental pollutants, tritiated water (HTO) and lead, was conducted. Sprague-Dawley rats were continuously exposed to HTO and/or Pb in drinking water from conception of the F 1 through adulthood of the F 2 generation. A l2-cell exposure matrix was used employing HTO activities calculated to provide approximately 3-300 mrad/d whole-body irradiation and Pb levels of 5 or 50 ppm in drinking water. Observations were made on the reproductive capacity of the F 1 generation and the effects of lifetime parental exposure to HTO and/or lead on the F 2 neonates. The effects of single and combined exposures on the development and function of the central nervous system, some brain catecholamine levels and electroencephalogram patterns were also examined in both generations. The results indicate that, in both generations, continuous HTO exposures as low as 3 mrad/d delayed development of righting reflexes in young rats; 30 mrad/d additionally depressed the spontaneous activity of adult male rats. Continuous exposure to 5 ppm lead produced similar effects on righting reflex development and adult spontaneous activity. The relative brain weight of F 2 neonates was decreased after lifetime parental exposure to 300 mrad/d or 5 and 50 ppm lead. Chronic lead exposure also appears to induce superovulation and increase preimplantation deaths in F 1 dams. Dose-effect responses to both HTO and lead were less than additive in their interactive effects on the parameters measured. (author)

  8. Bioactive glass/hydroxyapatite composites: mechanical properties and biological evaluation.

    Science.gov (United States)

    Bellucci, Devis; Sola, Antonella; Anesi, Alexandre; Salvatori, Roberta; Chiarini, Luigi; Cannillo, Valeria

    2015-06-01

    Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the samples at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference samples due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the samples themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Cardiac implantable electronic device lead extraction using the lead-locking device system: keeping it simple, safe, and inexpensive with mechanical tools and local anesthesia.

    Science.gov (United States)

    Manolis, Antonis S; Georgiopoulos, Georgios; Metaxa, Sofia; Koulouris, Spyridon; Tsiachris, Dimitris

    2017-10-01

    We have previously reported our successful approach for percutaneous cardiac implantable electronic device (CIED) lead extraction using inexpensive tools, which we have continued over the years. Herein we report the results of the systematic use of a unique stylet, the lead-locking device (LLD), which securely locks the entire lead lumen, aided with non-powered telescoping sheaths in 54 patients to extract 98 CIED leads. This prospective observational clinical study included 38 men and 16 women aged 68.9±13.1 years undergoing lead extraction for device infection (n=46), lead malfunction (n=5), or prior to defibrillator implant (n=3). Leads were in place for 6.7±4.3 years. Infections were more commonly due to Staphylococcus species (n=40). There were 78 pacing (31 ventricular, 37 atrial, 4 VDD, and 6 coronary sinus leads) and 20 defibrillating leads. Using simple traction (6 leads) and the LLD stylets (92 leads) aided with telescoping sheaths (15 patients), 96 (98%) leads in 52 (96.3%) patients were successfully removed, with all but one leads removed using a subclavian approach; in 1 patient, the right femoral approach was also required. In 2 patients, distal fragments from one ventricular pacing and one defibrillating lead could not be removed. Finally, lead removal was completely (52/54) (96.3%) or partially (2/54) (3.7%) successful in 54 patients for 96 of 98 leads (98%) without major complications. Percutaneous lead extraction can be successful with mechanical tools using the LLD locking stylet aided with non-powered telescoping sheaths through a simplified, safe, and inexpensive procedure using local anesthesia.

  10. The role of mechanics in biological and bio-inspired systems.

    Science.gov (United States)

    Egan, Paul; Sinko, Robert; LeDuc, Philip R; Keten, Sinan

    2015-07-06

    Natural systems frequently exploit intricate multiscale and multiphasic structures to achieve functionalities beyond those of man-made systems. Although understanding the chemical make-up of these systems is essential, the passive and active mechanics within biological systems are crucial when considering the many natural systems that achieve advanced properties, such as high strength-to-weight ratios and stimuli-responsive adaptability. Discovering how and why biological systems attain these desirable mechanical functionalities often reveals principles that inform new synthetic designs based on biological systems. Such approaches have traditionally found success in medical applications, and are now informing breakthroughs in diverse frontiers of science and engineering.

  11. A study on the ranges of low energy ions in biological samples and its mechanism of biological effects

    International Nuclear Information System (INIS)

    Lu Ting; Xie Liqing; Li Junping; Xia Ji

    1993-01-01

    The seeds of wheat and bean are irradiated by iron ion beam with energy 100 keV. The RBS spectra of the samples are observed and the ranges and distributions of the iron ions in the wheat and bean are calculated theoretically by means of Monte Carlo method. The results of theory and experiment are compared and the mechanism of biological effects induced by ion is discussed

  12. Reconstitution of a eukaryotic replisome reveals suppression mechanisms that define leading/lagging strand operation

    Science.gov (United States)

    Georgescu, Roxana E; Schauer, Grant D; Yao, Nina Y; Langston, Lance D; Yurieva, Olga; Zhang, Dan; Finkelstein, Jeff; O'Donnell, Mike E

    2015-01-01

    We have reconstituted a eukaryotic leading/lagging strand replisome comprising 31 distinct polypeptides. This study identifies a process unprecedented in bacterial replisomes. While bacteria and phage simply recruit polymerases to the fork, we find that suppression mechanisms are used to position the distinct eukaryotic polymerases on their respective strands. Hence, Pol ε is active with CMG on the leading strand, but it is unable to function on the lagging strand, even when Pol δ is not present. Conversely, Pol δ-PCNA is the only enzyme capable of extending Okazaki fragments in the presence of Pols ε and α. We have shown earlier that Pol δ-PCNA is suppressed on the leading strand with CMG (Georgescu et al., 2014). We propose that CMG, the 11-subunit helicase, is responsible for one or both of these suppression mechanisms that spatially control polymerase occupancy at the fork. DOI: http://dx.doi.org/10.7554/eLife.04988.001 PMID:25871847

  13. Transient resetting: a novel mechanism for synchrony and its biological examples.

    Directory of Open Access Journals (Sweden)

    Chunguang Li

    2006-08-01

    Full Text Available The study of synchronization in biological systems is essential for the understanding of the rhythmic phenomena of living organisms at both molecular and cellular levels. In this paper, by using simple dynamical systems theory, we present a novel mechanism, named transient resetting, for the synchronization of uncoupled biological oscillators with stimuli. This mechanism not only can unify and extend many existing results on (deterministic and stochastic stimulus-induced synchrony, but also may actually play an important role in biological rhythms. We argue that transient resetting is a possible mechanism for the synchronization in many biological organisms, which might also be further used in the medical therapy of rhythmic disorders. Examples of the synchronization of neural and circadian oscillators as well as a chaotic neuron model are presented to verify our hypothesis.

  14. Synergy and interactions among biological pathways leading to preterm premature rupture of membranes.

    Science.gov (United States)

    Lannon, Sophia M R; Vanderhoeven, Jeroen P; Eschenbach, David A; Gravett, Michael G; Adams Waldorf, Kristina M

    2014-10-01

    Preterm premature rupture of membranes (PPROM) occurs in 1% to 2% of births. Impact of PPROM is greatest in low- and middle-income countries where prematurity-related deaths are most common. Recent investigations identify cytokine and matrix metalloproteinase activation, oxidative stress, and apoptosis as primary pathways to PPROM. These biological processes are initiated by heterogeneous etiologies including infection/inflammation, placental bleeding, uterine overdistention, and genetic polymorphisms. We hypothesize that pathways to PPROM overlap and act synergistically to weaken membranes. We focus our discussion on membrane composition and strength, pathways linking risk factors to membrane weakening, and future research directions to reduce the global burden of PPROM. © The Author(s) 2014.

  15. Mechanism of formation and spatial distribution of lead atoms in quartz tube atomizers

    Science.gov (United States)

    Johansson, M.; Baxter, D. C.; Ohlsson, K. E. A.; Frech, W.

    1997-05-01

    The cross-sectional and longitudinal spatial distributions of lead atoms in a quartz tube (QT) atomizers coupled to a gas chromatograph have been investigated. A uniform analyte atom distribution over the cross-section was found in a QT having an inner diameter (i.d.) of 7 mm, whereas a 10 mm i.d. QT showed an inhomogeneous distribution. These results accentuate the importance of using QTs with i.d.s below 10 mm to fulfil the prerequirement of the Beer—Lambert law to avoid bent calibration curves. The influence of the make up gas on the formation of lead atoms from alkyllead compounds has been studied, and carbon monoxide was found equally efficient in promoting free atom formation as hydrogen. This suggests that hydrogen radicals are not essential for mediating the atomization of alkyllead in QT atomizers at ˜ 1200 K. Furthermore, thermodynamic equilibrium calculations describing the investigated system were performed supporting the experimental results. Based on the presented data, a mechanism for free lead atom formation in continuously heated QT atomizers is proposed; thermal atomization occurs under thermodynamic equilibrium conditions in a reducing gas. The longitudinal atom distribution has been further investigated applying other make up gases, N 2 and He. These results show the effect of the influx of atmospheric oxygen on the free lead atom formation. Calculations of the partial pressure of oxygen in the atomizer gas phase assuming thermodynamic equilibrium have been undertaken using a convective-diffusional model.

  16. Microwave emission from lead zirconate titanate induced by impulsive mechanical load

    Energy Technology Data Exchange (ETDEWEB)

    Aman, A., E-mail: alexander.aman@ovgu.de [Department of Engineering, Brandenburg University of Applied Science, 14470 Brandenburg an derHavel (Germany); Packaging Group, Institute of Micro- and Sensorsytems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany); Majcherek, S. [Packaging Group, Institute of Micro- and Sensorsytems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany); Hirsch, S. [Department of Engineering, Brandenburg University of Applied Science, 14470 Brandenburg an derHavel (Germany); Schmidt, B. [Chair of Micorsystem Technology, Institute of Micro- and Sensorsytems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany)

    2015-10-28

    This paper focuses on microwave emission from Lead zirconate titanate Pb [Zr{sub x}Ti{sub 1−x}] O{sub 3} (PZT) induced by mechanical stressing. The mechanical stress was initiated by impact of a sharp tungsten indenter on the upper surface of PZT ceramic. The sequences of microwave and current impulses, which flew from indenter to electric ground, were detected simultaneously. The voltage between the upper and lower surface of ceramic was measured to obtain the behavior of mechanical force acting on ceramic during the impact. It was found that the amplitude, form, and frequency of measured microwave impulses were different by compression and restitution phase of impact. Two different mechanisms of electron emission, responsible for microwave impulse generation, were proposed based on the dissimilar impulse behavior. The field emission from tungsten indenter is dominant during compression, whereas ferroemission dominates during restitution phase. Indeed, it was observed that the direction of the current flow, i.e., sign of current impulses is changed by transitions from compression to restitution phase of impact. The observed dissimilar behavior of microwave impulses, caused by increasing and decreasing applied force, can be used to calculate the contact time and behavior of mechanical force during mechanical impact on ceramic surface. It is shown that the generation of microwave impulses exhibits high reproducibility, impulse intensity, a low damping factor, and high mechanical failure resistance. Based on these microwave emission properties of PZT, the development of new type of stress sensor with spatial resolution of few microns becomes possible.

  17. A Model of How Different Biology Experts Explain Molecular and Cellular Mechanisms

    Science.gov (United States)

    Trujillo, Caleb M.; Anderson, Trevor R.; Pelaez, Nancy J.

    2015-01-01

    Constructing explanations is an essential skill for all science learners. The goal of this project was to model the key components of expert explanation of molecular and cellular mechanisms. As such, we asked: What is an appropriate model of the components of explanation used by biology experts to explain molecular and cellular mechanisms? Do…

  18. Mechanisms of collective cell movement lacking a leading or free front edge in vivo.

    Science.gov (United States)

    Uechi, Hiroyuki; Kuranaga, Erina

    2017-08-01

    Collective cell movement is one of the strategies for achieving the complex shapes of tissues and organs. In this process, multiple cells within a group held together by cell-cell adhesion acquire mobility and move together in the same direction. In some well-studied models of collective cell movement, the mobility depends strongly on traction generated at the leading edge by cells located at the front. However, recent advances in live-imaging techniques have led to the discovery of other types of collective cell movement lacking a leading edge or even a free edge at the front, in a diverse array of morphological events, including tubule elongation, epithelial sheet extension, and tissue rotation. We herein review some of the developmental events that are organized by collective cell movement and attempt to elucidate the underlying cellular and molecular mechanisms, which include membrane protrusions, guidance cues, cell intercalation, and planer cell polarity, or chirality pathways.

  19. Lead toxicity in rice: effects, mechanisms, and mitigation strategies--a mini review.

    Science.gov (United States)

    Ashraf, Umair; Kanu, Adam Sheka; Mo, Zhaowen; Hussain, Saddam; Anjum, Shakeel Ahmad; Khan, Imran; Abbas, Rana Nadeem; Tang, Xiangru

    2015-12-01

    Lead (Pb) is a major environmental pollutant that affects plant morpho-physiological and biochemical attributes. Its higher levels in the environment are not only toxic to human beings but also harmful for plants and soil microbes. We have reviewed the uptake, translocation, and accumulation mechanisms of Pb and its toxic effects on germination, growth, yield, nutrient relation, photosynthesis, respiration, oxidative damage, and antioxidant defense system of rice. Lead toxicity hampers rice germination, root/shoot length, growth, and final yield. It reduces nutrient uptake through roots, disrupts chloroplastic ultrastructure and cell membrane permeability, induces alterations in leaves respiratory activities, produces reactive oxygen species (ROS), and triggers some enzyme and non-enzymatic antioxidants (as defense to oxidative damage). In the end, biochar amendments and phytoremediation technologies have been proposed as soil remediation approaches for Pb tainted soils.

  20. Fatigue responses of lead zirconate titanate stacks under semibipolar electric cycling with mechanical preload

    Science.gov (United States)

    Wang, Hong; Cooper, Thomas A.; Lin, Hua-Tay; Wereszczak, Andrew A.

    2010-10-01

    Lead zirconate titanate (PZT) stacks that had an interdigital internal electrode configuration were tested to more than 108 cycles. A 100 Hz semibipolar sine wave with a field range of +4.5/-0.9 kV/mm was used in cycling with a concurrently-applied 20 MPa preload. Significant reductions in piezoelectric and dielectric responses were observed during the cycling depending on the measuring condition. Extensive partial discharges were also observed. These surface events resulted in the erosion of external electrode and the exposure of internal electrodes. Sections prepared by sequential polishing technique revealed a variety of damage mechanisms including delaminations, pores, and etch grooves. The scale of damage was correlated with the degree of fatigue-induced reduction in piezoelectric and dielectric responses. The results from this study demonstrate the feasibility of using a semibipolar mode to drive a PZT stack under a mechanical preload and illustrate the potential fatigue and damages of the stack in service.

  1. INFRASTRUCTURAL MECHANISMS LEADING TOWARD PRO-ACCOUNTABLE CARE ORGANISATION ORIENTATION: A SURVEY OF HOSPITAL MANAGERS

    Science.gov (United States)

    Wan, Thomas T.H.; Masri, Maysoun Dimachkie; Ortiz, Judith

    2013-01-01

    Organisations across the country are transforming the way they deliver care, in ways similar to the accountable care organisation (ACO) model supported by Medicare. ACOs modalities are varying in size, type, and financing structure. Little is known about how specific infrastructural mechanisms influence hospital managers’ pro-ACO orientation. Using an electronic-survey of hospital managers, this study explores how pro-ACO orientation, as a latent construct, is captured from the perceptions of hospital managers; and identify infrastructural mechanisms leading to the formation of pro-ACO orientation. Of the total hospital respondents, 58% are moving toward the establishment of ACOs; 56% are planning to join in the next two years; 48% are considering joining ACOs; while 25% had already participated in ACOs during 2012. Urban hospitals are more likely than rural hospitals to be engaged in ACO development. The health provider network size is one of the strongest indicators in predicting pro-ACO orientation. PMID:25374609

  2. Change is good: variations in common biological mechanisms in the epsilonproteobacterial genera Campylobacter and Helicobacter.

    Science.gov (United States)

    Gilbreath, Jeremy J; Cody, William L; Merrell, D Scott; Hendrixson, David R

    2011-03-01

    Microbial evolution and subsequent species diversification enable bacterial organisms to perform common biological processes by a variety of means. The epsilonproteobacteria are a diverse class of prokaryotes that thrive in diverse habitats. Many of these environmental niches are labeled as extreme, whereas other niches include various sites within human, animal, and insect hosts. Some epsilonproteobacteria, such as Campylobacter jejuni and Helicobacter pylori, are common pathogens of humans that inhabit specific regions of the gastrointestinal tract. As such, the biological processes of pathogenic Campylobacter and Helicobacter spp. are often modeled after those of common enteric pathogens such as Salmonella spp. and Escherichia coli. While many exquisite biological mechanisms involving biochemical processes, genetic regulatory pathways, and pathogenesis of disease have been elucidated from studies of Salmonella spp. and E. coli, these paradigms often do not apply to the same processes in the epsilonproteobacteria. Instead, these bacteria often display extensive variation in common biological mechanisms relative to those of other prototypical bacteria. In this review, five biological processes of commonly studied model bacterial species are compared to those of the epsilonproteobacteria C. jejuni and H. pylori. Distinct differences in the processes of flagellar biosynthesis, DNA uptake and recombination, iron homeostasis, interaction with epithelial cells, and protein glycosylation are highlighted. Collectively, these studies support a broader view of the vast repertoire of biological mechanisms employed by bacteria and suggest that future studies of the epsilonproteobacteria will continue to provide novel and interesting information regarding prokaryotic cellular biology.

  3. Fracture Mechanics Analyses of Reinforced Carbon-Carbon Wing-Leading-Edge Panels

    Science.gov (United States)

    Raju, Ivatury S.; Phillips, Dawn R.; Knight, Norman F., Jr.; Song, Kyongchan

    2010-01-01

    Fracture mechanics analyses of subsurface defects within the joggle regions of the Space Shuttle wing-leading-edge RCC panels are performed. A 2D plane strain idealized joggle finite element model is developed to study the fracture behavior of the panels for three distinct loading conditions - lift-off and ascent, on-orbit, and entry. For lift-off and ascent, an estimated bounding aerodynamic pressure load is used for the analyses, while for on-orbit and entry, thermo-mechanical analyses are performed using the extreme cold and hot temperatures experienced by the panels. In addition, a best estimate for the material stress-free temperature is used in the thermo-mechanical analyses. In the finite element models, the substrate and coating are modeled separately as two distinct materials. Subsurface defects are introduced at the coating-substrate interface and within the substrate. The objective of the fracture mechanics analyses is to evaluate the defect driving forces, which are characterized by the strain energy release rates, and determine if defects can become unstable for each of the loading conditions.

  4. Biochemical mechanism of phytoremediation process of lead and cadmium pollution with Mucor circinelloides and Trichoderma asperellum.

    Science.gov (United States)

    Zhang, Xu; Li, Xinxin; Yang, Huanhuan; Cui, Zhaojie

    2018-08-15

    This study focused on the bioremediation mechanisms of lead (0, 100, 500, 1000 mg kg -1 ) and cadmium (0,10,50,100 mg kg -1 ) contaminated soil using two indigenous fungi selected from mine tailings as the phytostimulation of Arabidopsis thaliana. The two fungal strains were characterized as Mucor circinelloides (MC) and Trichoderma asperellum (TA) by internal transcribed spacer sequencing at the genetic levels. Our research revealed that Cadmium was more toxic to plant growth than lead and meanwhile, MC and TA can strengthen A. thaliana tolerance to cadmium and lead with 40.19-117.50% higher root length and 58.31-154.14% shoot fresh weight of plant compared to non-inoculation. In this study, TA exhibited a higher potential to the inactivation of cadmium; however, MC was more effective in lead passivation. There was a direct correlation between the type of fungi, heavy metal content, heavy metal type and oxidative damage in plant. Both lead and cadmium induced oxidative damage as indicated by increased superoxide dismutase and catalase activities, while the antioxidant levels were significantly higher in fungal inoculated plants compared with those non-inoculated. The analysis of soil enzyme activity and taxonomic richness uncovered that the dominant structures of soil microbial community were altered by exogenous microbial agents. MC enhanced higher microbial diversity and soil enzyme activity than TA. The two indigenous fungi lessened several limiting factors with respect to phytoremediation technology, such as soil chemistry, contamination level and transformation, and metal solubility. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. Biologically important conformational features of DNA as interpreted by quantum mechanics and molecular mechanics computations of its simple fragments.

    Science.gov (United States)

    Poltev, V; Anisimov, V M; Dominguez, V; Gonzalez, E; Deriabina, A; Garcia, D; Rivas, F; Polteva, N A

    2018-02-01

    Deciphering the mechanism of functioning of DNA as the carrier of genetic information requires identifying inherent factors determining its structure and function. Following this path, our previous DFT studies attributed the origin of unique conformational characteristics of right-handed Watson-Crick duplexes (WCDs) to the conformational profile of deoxydinucleoside monophosphates (dDMPs) serving as the minimal repeating units of DNA strand. According to those findings, the directionality of the sugar-phosphate chain and the characteristic ranges of dihedral angles of energy minima combined with the geometric differences between purines and pyrimidines determine the dependence on base sequence of the three-dimensional (3D) structure of WCDs. This work extends our computational study to complementary deoxydinucleotide-monophosphates (cdDMPs) of non-standard conformation, including those of Z-family, Hoogsteen duplexes, parallel-stranded structures, and duplexes with mispaired bases. For most of these systems, except Z-conformation, computations closely reproduce experimental data within the tolerance of characteristic limits of dihedral parameters for each conformation family. Computation of cdDMPs with Z-conformation reveals that their experimental structures do not correspond to the internal energy minimum. This finding establishes the leading role of external factors in formation of the Z-conformation. Energy minima of cdDMPs of non-Watson-Crick duplexes demonstrate different sequence-dependence features than those known for WCDs. The obtained results provide evidence that the biologically important regularities of 3D structure distinguish WCDs from duplexes having non-Watson-Crick nucleotide pairing.

  6. Quantum Information Biology: From Information Interpretation of Quantum Mechanics to Applications in Molecular Biology and Cognitive Psychology

    Science.gov (United States)

    Asano, Masanari; Basieva, Irina; Khrennikov, Andrei; Ohya, Masanori; Tanaka, Yoshiharu; Yamato, Ichiro

    2015-10-01

    We discuss foundational issues of quantum information biology (QIB)—one of the most successful applications of the quantum formalism outside of physics. QIB provides a multi-scale model of information processing in bio-systems: from proteins and cells to cognitive and social systems. This theory has to be sharply distinguished from "traditional quantum biophysics". The latter is about quantum bio-physical processes, e.g., in cells or brains. QIB models the dynamics of information states of bio-systems. We argue that the information interpretation of quantum mechanics (its various forms were elaborated by Zeilinger and Brukner, Fuchs and Mermin, and D' Ariano) is the most natural interpretation of QIB. Biologically QIB is based on two principles: (a) adaptivity; (b) openness (bio-systems are fundamentally open). These principles are mathematically represented in the framework of a novel formalism— quantum adaptive dynamics which, in particular, contains the standard theory of open quantum systems.

  7. Dissolution mechanism of austenitic stainless steels in lead-bismuth eutectic at 500 deg. C

    International Nuclear Information System (INIS)

    Roy, M.

    2012-01-01

    In the framework of the future nuclear power plants studies, lead-bismuth eutectic (LBE) is foreseen as a coolant in the primary or the secondary circuit in three nuclear systems. The use of this liquid alloy induces corrosion issues for structural steels. In liquid lead alloys, steels can undergo two corrosion phenomena: dissolution or oxidation depending on the temperature and the dissolved oxygen content in LBE. The goal of this study is to identify the dissolution mechanisms of austenitic steels in LBE at 500 deg. C. Four Fe-Cr-Ni model austenitic steels, the 316L steel and five other industrial steels were corroded in LBE up to, respectively, 3000, 6000 and 200 h. The dissolution mechanism is identical for all steels: it starts by a preferential dissolution of chromium and nickel. This dissolution leads to the formation of a ferritic corrosion layer penetrated by LBE and containing between 5 and 10 at% of chromium and almost no nickel. This study demonstrates that dissolutions of nickel and chromium are linked. Otherwise, the corrosion kinetics is linear whatever the tested austenitic steel. The controlling steps of the austenitic steels' corrosion rates have been identified. Natural convection in the LBE bath leads to the formation of a diffusion boundary layer at the steel surface. Chromium diffusion in this diffusion boundary layer seems to control the corrosion rates of the model and industrial austenitic steels except the 316L steel. Indeed, the corrosion rate of the 316L steel is controlled by an interfacial reaction which is either the simultaneous dissolution of nickel and chromium in Ni, Cr compounds or the nickel and chromium dissolution catalyzed by the dissolved oxygen in LBE. This study has permitted to highlight the major role of chromium on the corrosion mechanisms and the corrosion rates of austenitic steels: the corrosion rate increases when chromium activity increases. Finally, the impact of the dissolved oxygen and the minor alloying

  8. Microdetermination of lead, cadmium, zinc and tin in biological and related materials by atomic absorption spectrometry after mineralisation and extraction

    International Nuclear Information System (INIS)

    Boiteau, H.L.; Metayer, C.

    1978-01-01

    Two technics permitting to determine either lead, cadmium and zinc, or tin in any biological material (blood, urines, organs, alimentary products of animal or vegetable origin) are described. Every operation (mineralisation and extraction) is made in the same tube and technics, conceived in a way to simplify the manipulations and to reduce the more possible the contamination risks are suitable for determination in series. By working on trial samples near 250 mg, the lower determination limits are around 2 ppb for cadmium, 40 ppb for lead and tin and 2 ppm for zinc. The repeatability studies of different technical stages show that mineralisation and extraction only have a weak incidence on the acccuracy of the results [fr

  9. Chemically induced aneuploidy in mammalian cells: mechanisms and biological significance in cancer

    Energy Technology Data Exchange (ETDEWEB)

    Oshimura, M.; Barrett, J.C.

    1986-01-01

    A literature review with over 200 references examines the growing body of evidence from human and animal cancer cytogenetics that aneuploidy is an important chromosome change in carcinogenesis. Evidence from in vitro cell transformation studies supports the idea that aneuploidy has a direct effect on the conversion of a normal cell to a preneoplastic or malignant cell. Induction of an aneuploid state in a preneoplastic or neoplastic cell could have any of the following four biological effects: a change in gene dosage, a change in gene balance, expression of a recessive mutation, or a change in genetic instability (which could secondarily lead to neoplasia). There are a number of possible mechanisms by which chemicals might induce aneuploidy, including effects on microtubules, damage to essential elements for chromosome function reduction in chromosome condensation or pairing, induction of chromosome interchanges, unresolved recombination structures, increased chromosome stickiness, damage to centrioles, impairment of chromosome alignment ionic alterations during mitosis, damage to the nuclear membrane, and a physical disruption of chromosome segregation. Therefore, a number of different targets exist for chemically induced aneuploidy.

  10. Epigenetic Mechanisms Shape the Biological Response to Trauma and Risk for PTSD: A Critical Review

    Directory of Open Access Journals (Sweden)

    Morgan Heinzelmann

    2013-01-01

    Full Text Available Posttraumatic stress disorder (PTSD develops in approximately one-quarter of trauma-exposed individuals, leading us and others to question the mechanisms underlying this heterogeneous response to trauma. We suggest that the reasons for the heterogeneity relate to a complex interaction between genes and the environment, shaping each individual’s recovery trajectory based on both historical and trauma-specific variables. Epigenetic modifications provide a unique opportunity to elucidate how preexisting risk factors may contribute to PTSD risk through changes in the methylation of DNA. Preexisting risks for PTSD, including depression, stress, and trauma, result in differential DNA methylation of endocrine genes, which may then result in a different biological responses to trauma and subsequently a greater risk for PTSD onset. Although these relationships are complex and currently inadequately described, we provide a critical review of recent studies to examine how differences in genetic and proteomic biomarkers shape an individual’s vulnerability to PTSD development, thereby contributing to a heterogeneous response to trauma.

  11. Changes in diffusion properties of biological tissues associated with mechanical strain

    International Nuclear Information System (INIS)

    Tanaka, Kenichiro; Imae, T.; Mima, Kazuo; Sekino, Masaki; Ohsaki, Hiroyuki; Ueno, Shogo

    2007-01-01

    Mechanical strain in biological tissues causes a change in the diffusion properties of water molecules. This paper proposes a method of estimating mechanical strain in biological tissues using diffusion magnetic resonance imaging (MRI). Measurements were carried out on uncompressed and compressed chicken skeletal muscles. A theoretical model of the diffusion of water molecules in muscle fibers was derived based on Tanner's equation. Diameter of the muscle fibers was estimated by fitting the model equation to the measured signals. Changes in the mean diffusivity (MD), the fractional anisotropy (FA), and diameter of the muscle fiber did not have any statistical significance. The intracellular diffusion coefficient (D int ) was changed by mechanical strain (p<.05). This method has potential applications in the quantitative evaluation of strain in biological tissues, a though it poses several technical challenges. (author)

  12. Potential of development of the mechanical-biological waste treatment; Entwicklungspotenzial der Mechanisch-Biologischen Abfallbehandlung

    Energy Technology Data Exchange (ETDEWEB)

    Grundmann, Thomas; Balhar, Michael [ASA e.V., Ennigerloh (Germany); Abfallwirtschaftsgesellschaft des Kreises Warendorf mbH, Ennigerloh (Germany)

    2013-03-01

    The Consortium Material-Specific Waste Treatment eV (Ennigerloh, Federal Republic of Germany) is an association of plant operators having the opinion that an economic and ecologic waste treatment only can be guaranteed by material-specific processes permanently. Due to the specific treatment processes in plants with mechanical-biological waste treatment (MBA) material flows are resulting being available for the recycling or exploitation. Under this aspect, the authors of the contribution under consideration report on the development potential of the mechanical-biological waste treatment. The state of the art of the technology of mechanical-biological waste treatment in Germany as well as the contribution of this technology to the resource protection and climate protection are described. Further aspects of this contribution are the increase of the energy efficiency and reduction of emissions; further development of the efficient sorting technology; development of integrated total conceptions - MBA-sites as centres for the production of renewable energies.

  13. Exposure assessment in Beijing, China: biological agents, ultrafine particles, and lead.

    Science.gov (United States)

    Dong, Shuofei; Yao, Maosheng

    2010-11-01

    In this study, air samples were taken using a BioSampler and gelatin filters from six sites in Beijing: office, hospital, student dormitory, train station, subway, and a commercial street. Dust samples were also collected using a surface sampler from the same environments. Limulus amoebocyte lysate (LAL) and Glucatell assays were used to quantify sample endotoxin and (1,3)-β-d-glucan concentration levels, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to measure the dust mite allergens (Der p 1 and Der f 1). Ultrafine particle and lead concentrations in these sampling sites were also measured using P-Trak and atomic absorption spectrometer, respectively. Analysis of variance (ANOVA) and linear regression analysis were used to analyze the concentration data. Higher culturable bacteria (12,639 CFU/m3) and fungi (1,806 CFU/m3) concentrations were observed for the train station and the subway system, respectively. For the rest of sampling sites, their concentrations were comparable to those found in western countries, ranging from 990 to 2,276 CFU/m3 for bacteria, and from 119 to 269 CFU/m3 for fungi. ANOVA analysis indicated that there were statistically significant differences between the culturable bacterial and fungal concentration levels obtained for different sites (p value=0.0001 and 0.0047). As for dust allergens, endotoxin, and (1,3)-β-D-glucan, their concentrations also seemed to be comparable to those found in the developed countries. Airborne allergen concentrations ranged from 16 to 68 ng/m3. The dust-borne allergen concentration was observed to range from 0.063 to 0.327 ng/mg. As for endotoxin, the highest airborne concentration of 25.24 ng/m3 was observed for the commercial street, and others ranged from 0.0427 to 0.1259 ng/m3. And dust-borne endotoxin concentration ranged from 58.83 to 6,427.4 ng/mg. For (1,3)-β-D-glucan, the airborne concentration ranged from 0.02 to 1.2 ng/m3. Linear regression analyses showed that there existed

  14. A Tryptoline Ring-Distortion Strategy Leads to Complex and Diverse Biologically Active Molecules from the Indole Alkaloid Yohimbine.

    Science.gov (United States)

    Paciaroni, Nicholas G; Ratnayake, Ranjala; Matthews, James H; Norwood, Verrill M; Arnold, Austin C; Dang, Long H; Luesch, Hendrik; Huigens, Robert W

    2017-03-28

    High-throughput screening (HTS) is the primary driver to current drug-discovery efforts. New therapeutic agents that enter the market are a direct reflection of the structurally simple compounds that make up screening libraries. Unlike medically relevant natural products (e.g., morphine), small molecules currently being screened have a low fraction of sp 3 character and few, if any, stereogenic centers. Although simple compounds have been useful in drugging certain biological targets (e.g., protein kinases), more sophisticated targets (e.g., transcription factors) have largely evaded the discovery of new clinical agents from screening collections. Herein, a tryptoline ring-distortion strategy is described that enables the rapid synthesis of 70 complex and diverse compounds from yohimbine (1); an indole alkaloid. The compounds that were synthesized had architecturally complex and unique scaffolds, unlike 1 and other scaffolds. These compounds were subjected to phenotypic screens and reporter gene assays, leading to the identification of new compounds that possessed various biological activities, including antiproliferative activities against cancer cells with functional hypoxia-inducible factors, nitric oxide inhibition, and inhibition and activation of the antioxidant response element. This tryptoline ring-distortion strategy can begin to address diversity problems in screening libraries, while occupying biologically relevant chemical space in areas critical to human health. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Recent advances in biological effect and molecular mechanism of arabidopsis thaliana irradiated by ion beams

    International Nuclear Information System (INIS)

    Wu Dali; Hou Suiwen; Li Wenjian

    2008-01-01

    Newly research progresses were summarized in effect of ion beams on seed surface, biological effect, growth, development, gravitropism and so on. Furthermore, mutation molecular mechanism of Arabidopsis thaliana was discussed, for example, alteration of DNA bases, DNA damage, chromosomal recombination, characteristics of mutant transmissibility, etc. Meanwhile, the achievements of transfer- ring extraneous gene to Arabidopsis thaliana by ion beams were reviewed in the paper. At last, the future prospective are also discussed here in mutation molecular mechanism and the potential application of biological effect of heavy ion beams. (authors)

  16. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Jahnavi, S [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Saravanan, U [Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Arthi, N [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Bhuvaneshwar, G S [Department of Engineering Design, Indian Institute of Technology Madras, Chennai, TN 600036 (India); Kumary, T V [Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Trivandrum, Kerala 695012 (India); Rajan, S [Madras Medical Mission, Institute of Cardio-Vascular Diseases, Mogappair, Chennai, Tamil Nadu 600037 (India); Verma, R S, E-mail: vermars@iitm.ac.in [Stem Cell and Molecular Biology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, TN 600036 (India)

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44{sup +}, αSMA{sup +}, Vimentin{sup +} and CD105{sup −} human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. - Highlights: • We report detailed biological and mechanical investigations of a Bio-Hybrid scaffold. • Optimized polymer thickness yielded desired biological and mechanical properties. • Bio-Hybrid scaffold revealed hVIC proliferation with dense ECM deposition. • Biaxial testing indicated that Bio-Hybrid scaffolds are mechanically stronger than native valves. • Bio-Hybrid scaffold is a promising material for autologous valve tissue engineering.

  17. Mechanisms leading to increased risk of preterm birth in growth-restricted guinea pig pregnancies.

    Science.gov (United States)

    Palliser, Hannah K; Kelleher, Meredith A; Welsh, Toni N; Zakar, Tamas; Hirst, Jonathan J

    2014-02-01

    Intrauterine growth restriction (IUGR) is a risk factor for preterm labor; however, the mechanisms of the relationship remain unknown. Prostaglandin (PG), key stimulants of labor, availability is regulated by the synthetic enzymes, prostaglandin endoperoxidases 1 and 2 (PTGS1 and 2), and the metabolizing enzyme, 15-hydroxyprostaglandin dehydrogenase (HPGD). We hypothesized that IUGR increases susceptibility to preterm labor due to the changing balance of synthetic and metabolizing enzymes and hence greater PG availability. We have tested this hypothesis using a surgically induced IUGR model in guinea pigs, which results in significantly shorter gestation. Myometrium, amnion, chorion, and placentas were collected from sham operated or IUGR pregnancies, and PTGS1 and HPGD protein expression were quantified throughout late gestation (>62 days) and labor. The PTGS1 expression was significantly upregulated in the myometrium of IUGR animals, and chorionic HPGD expression was markedly decreased (P production over metabolism in IUGR pregnancies leads to a greater susceptibility to preterm birth.

  18. An introduction to the mechanisms leading to density-wave instabilities in BWRs

    International Nuclear Information System (INIS)

    March-Leuba, Jose

    2004-01-01

    This paper presents a review of the physical mechanisms that lead to density-wave instabilities in boiling water reactors (BWRs). The goal of this paper is not to present new information; but ideas that are generally known and accepted in the field of BWR stability. The number of people working in the field of BWR stability has grown over the past years to a significant number; nevertheless, the field is still small enough so that personal communication is an effective way of conveying information. The unfortunate consequence is that this field has a large component of ''art'' as opposed to science.'' This paper attempts to summarize these basic ideas for the reader. (author)

  19. Comparison of the key mechanisms leading to rollovers in Liquefied Natural Gas using Computational Fluid Dynamics

    Science.gov (United States)

    Hubert, Antoine; Dadonau, Maksim; Dembele, Siaka; Denissenko, Petr; Wen, Jennifer

    2017-11-01

    Growing demand for the LNG fosters growth of the number of production sites with varying composition and density. Combining different sources of LNG may result in a stably stratified system, in which heat and mass transfer between the layers is limited. Heating of the LNG due to wall thermal conductivity leads to formation of convection cells confined within the layers. While the upper layer can release the extra energy via preferential methane boil-off, the bottom layer cannot and hence becomes superheated. Gradual density equilibration reduces stratification and may eventually lead to a sudden mixing event called ``rollover'', accompanied by violent evaporation of the superheated LNG. Three phenomena are potentially responsible for density equilibration. The first is the growing difference in thermal expansion of the layers due to the reduced ability of the bottom layer to reject heat. The second is the penetration of the heated near-wall boundary layer into the upper layer. The third is the ``entrainment mixing'' occurring at the contact surface between the two layers. The present study uses CFD to compare these mechanisms. Boussinesq approximation and an extended version of the k- ɛ model is used. The code is validated by comparison with a large-scale LNG rollover experiment.

  20. Space Shuttle Orbiter Wing-Leading-Edge Panel Thermo-Mechanical Analysis for Entry Conditions

    Science.gov (United States)

    Knight, Norman F., Jr.; Song, Kyongchan; Raju, Ivatury S.

    2010-01-01

    Linear elastic, thermo-mechanical stress analyses of the Space Shuttle Orbiter wing-leading-edge panels is presented for entry heating conditions. The wing-leading-edge panels are made from reinforced carbon-carbon and serve as a part of the overall thermal protection system. Three-dimensional finite element models are described for three configurations: integrated configuration, an independent single-panel configuration, and a local lower-apex joggle segment. Entry temperature conditions are imposed and the through-the-thickness response is examined. From the integrated model, it was concluded that individual panels can be analyzed independently since minimal interaction between adjacent components occurred. From the independent single-panel model, it was concluded that increased through-the-thickness stress levels developed all along the chord of a panel s slip-side joggle region, and hence isolated local joggle sections will exhibit the same trend. From the local joggle models, it was concluded that two-dimensional plane-strain models can be used to study the influence of subsurface defects along the slip-side joggle region of these panels.

  1. Fracture Mechanics Analyses of the Slip-Side Joggle Regions of Wing-Leading Edge Panels

    Science.gov (United States)

    Raju, Ivatury S.; Knight, Norman F., Jr.; Song, Kyongchan; Phillips, Dawn R.

    2010-01-01

    The Space Shuttle Orbiter wing comprises of 22 leading edge panels on each side of the wing. These panels are part of the thermal protection system that protects the Orbiter wings from extreme heating that take place on the reentry in to the earth atmosphere. On some panels that experience extreme heating, liberation of silicon carbon (SiC) coating was observed on the slip side regions of the panels. Global structural and local fracture mechanics analyses were performed on these panels as a part of the root cause investigation of this coating liberation anomaly. The wing-leading-edge reinforced carbon-carbon (RCC) panels, Panel 9, T-seal 10, and Panel 10, are shown in Figure 1 and the progression of the stress analysis models is presented in Figure 2. The global structural analyses showed minimal interaction between adjacent panels and the T-seal that bridges the gap between the panels. A bounding uniform temperature is applied to a representative panel and the resulting stress distribution is examined. For this loading condition, the interlaminar normal stresses showed negligible variation in the chord direction and increased values in the vicinity of the slip-side joggle shoulder. As such, a representative span wise slice on the panel can be taken and the cross section can be analyzed using plane strain analysis.

  2. Fluorometric detection of nitroaromatics by fluorescent lead complexes: A spectroscopic assessment of detection mechanism

    Science.gov (United States)

    Chattopadhyay, Tanmay; Chatterjee, Sourav; Majumder, Ishani; Ghosh, Soumen; Yoon, Sangee; Sim, Eunji

    2018-04-01

    Three Schiff base ligands such as 2-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL1), 2-[(2-Hydroxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL2), 2-[(3,5-Dichloro-2-hydroxy-benzylidene)-amino]-2-hydroxymethyl-propane-1,3-diol (HL3) have been synthesized by condensation of aldehydes (such as 3,5-Dichloro-2-hydroxy benzaldehyde, 2-Hydroxy-benzaldehyde, and 2-Hydroxy-3-methoxy-benzaldehyde) with Tris-(hydroxymethyl)amino methane and characterized by IR, UV-vis and 1H NMR spectroscopy. Then all these three ligands have been used to prepare Pb(II) complexes by reaction with lead(II) acetate tri-hydrate in methanol. In view of analytical and spectral (IR, UV-vis and Mass) studies, it has been concluded that, except HL2, other two ligands form 1:1 metal complexes (1 and 3) with lead. Between two complexes, complex 3 is highly fluorescent and this property has been used to identify the pollutant nitroaromatics. Finally, the quenching mechanism has been established by means of spectroscopic investigation.

  3. Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric

    DEFF Research Database (Denmark)

    Walker, Julian; Simons, Hugh; Alikin, Denis O

    2016-01-01

    Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb)-based ferroe......Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb......)-based ferroelectric ceramics. In the search for Pb-free alternatives, systems with MPBs between polar and non-polar phases have recently been theorized as having great promise. While such an MPB was identified in rare-earth (RE) modified bismuth ferrite (BFO) thin films, synthesis challenges have prevented its...... realization in ceramics. Overcoming these, we demonstrate a comparable electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm modified BFO. This arises from 'dual' strain mechanisms: ferroelectric/ferroelastic switching and a previously unreported electric-field induced...

  4. A first principles study of the mechanical, electronic, and vibrational properties of lead oxide

    Science.gov (United States)

    Zhuravlev, Yu. N.; Korabel'nikov, D. V.

    2017-11-01

    The first principles study of the crystal structure, chemical bonds, elastic and mechanical properties, electron energy band structure and density, and normal long-wave vibrations of nine phases of lead monoxide, dioxide, and tetraoxide has been performed under normal and external pressure within the framework of density functional theory (DFT) with the Perdew-Becke-Ernzerhof (PBE) gradient exchange-correlation functional and its hybrid version with a 25-% Hartree-Fock (HF) exchange contribution in the basis of localized atom orbitals. The behavior of physical parameters has been studied using the cold four- and threeparameter equations of state. The parameters of the crystal structures are in satisfactory agreement with experimental data, and elastic constants indicate their mechanical stability and anisotropy in the elastic properties. The elasticity, shear, and Young moduli, hardness, acoustic velocities, and Debye temperature of dioxide on the one hand and monoxide and tetraoxide on the other hand appreciably differ from each other. The difference between electron properties may be explained by the character of hybridization in the upper filled and lower empty energy bands as evident from the density of states. In monoxide, the indirect band gap width decreases with increasing pressure at a rate of 0.16 eV/GPa, and the direct band gap width increases at a rate of 0.13 eV/GPa. To identify crystalline phases, the frequencies and intensities of long-wave modes active in IR and Raman spectra have been calculated.

  5. Presynaptic mechanisms of lead neurotoxicity: effects on vesicular release, vesicle clustering and mitochondria number.

    Science.gov (United States)

    Zhang, Xiao-Lei; Guariglia, Sara R; McGlothan, Jennifer L; Stansfield, Kirstie H; Stanton, Patric K; Guilarte, Tomás R

    2015-01-01

    Childhood lead (Pb2+) intoxication is a global public health problem and accounts for 0.6% of the global burden of disease associated with intellectual disabilities. Despite the recognition that childhood Pb2+ intoxication contributes significantly to intellectual disabilities, there is a fundamental lack of knowledge on presynaptic mechanisms by which Pb2+ disrupts synaptic function. In this study, using a well-characterized rodent model of developmental Pb2+ neurotoxicity, we show that Pb2+ exposure markedly inhibits presynaptic vesicular release in hippocampal Schaffer collateral-CA1 synapses in young adult rats. This effect was associated with ultrastructural changes which revealed a reduction in vesicle number in the readily releasable/docked vesicle pool, disperse vesicle clusters in the resting pool, and a reduced number of presynaptic terminals with multiple mitochondria with no change in presynaptic calcium influx. These studies provide fundamental knowledge on mechanisms by which Pb2+ produces profound inhibition of presynaptic vesicular release that contribute to deficits in synaptic plasticity and intellectual development.

  6. Mechanism of inhibition of human secretory phospholipase A2 by flavonoids: rationale for lead design

    Science.gov (United States)

    Lättig, Jens; Böhl, Markus; Fischer, Petra; Tischer, Sandra; Tietböhl, Claudia; Menschikowski, Mario; Gutzeit, Herwig O.; Metz, Peter; Pisabarro, M. Teresa

    2007-08-01

    The human secretory phospholipase A2 group IIA (PLA2-IIA) is a lipolytic enzyme. Its inhibition leads to a decrease in eicosanoids levels and, thereby, to reduced inflammation. Therefore, PLA2-IIA is of high pharmacological interest in treatment of chronic diseases such as asthma and rheumatoid arthritis. Quercetin and naringenin, amongst other flavonoids, are known for their anti-inflammatory activity by modulation of enzymes of the arachidonic acid cascade. However, the mechanism by which flavonoids inhibit Phospholipase A2 (PLA2) remained unclear so far. Flavonoids are widely produced in plant tissues and, thereby, suitable targets for pharmaceutical extractions and chemical syntheses. Our work focuses on understanding the binding modes of flavonoids to PLA2, their inhibition mechanism and the rationale to modify them to obtain potent and specific inhibitors. Our computational and experimental studies focused on a set of 24 compounds including natural flavonoids and naringenin-based derivatives. Experimental results on PLA2-inhibition showed good inhibitory activity for quercetin, kaempferol, and galangin, but relatively poor for naringenin. Several naringenin derivatives were synthesized and tested for affinity and inhibitory activity improvement. 6-(1,1-dimethylallyl)naringenin revealed comparable PLA2 inhibition to quercetin-like compounds. We characterized the binding mode of these compounds and the determinants for their affinity, selectivity, and inhibitory potency. Based on our results, we suggest C(6) as the most promising position of the flavonoid scaffold to introduce chemical modifications to improve affinity, selectivity, and inhibition of PLA2-IIA by flavonoids.

  7. On the mechanisms of interaction of low-intensity millimeter waves with biological objects

    Energy Technology Data Exchange (ETDEWEB)

    Betskii, O.V.

    1994-07-01

    The interaction of low-intensity millimeter-band electromagnetic waves with biological objects is examined. These waves are widely used in medical practice as a means of physiotherapy for the treatment of various human disorders. Principal attention is given to the mechanisms through which millimeter waves act on the human organism.

  8. I'm so tired: biological and genetic mechanisms of cancer-related fatigue

    NARCIS (Netherlands)

    Barsevick, Andrea; Frost, Marlene; Zwinderman, Aeilko; Hall, Per; Halyard, Michele; Abertnethy, Amy P.; Baas, Frank; Barsevick, Andrea M.; Bartels, Meike; Boomsma, Dorret I.; Chauhan, Cynthia; Cleeland, Charles S.; Dueck, Amylou C.; Frost, Marlene H.; Halyard, Michele Y.; Klepstad, Pål; Martin, Nicholas G.; Miaskowski, Christine; Mosing, Miriam; Movsas, Benjamin; van Noorden, Cornelis J. F.; Patrick, Donald L.; Pedersen, Nancy L.; Ropka, Mary E.; Shi, Quiling; Shinozaki, Gen; Singh, Jasvinder A.; Sloan, Jeff A.; Sprangers, Mirjam A. G.; Veenhoven, Ruut; Yang, Ping

    2010-01-01

    Objective The goal of this paper is to discuss cancer-related fatigue (CRF) and address issues related to the investigation into potential biological and genetic causal mechanisms. The objectives are to: (1) describe CRF as a component of quality of life (QOL); (2) address measurement issues that

  9. How preconditioning affects the measurement of poro-viscoelastic mechanical properties in biological tissues

    NARCIS (Netherlands)

    Hosseini, S.M.; Wilson, W.; Ito, K.; Donkelaar, van C.C.

    2014-01-01

    It is known that initial loading curves of soft biological tissues are substantially different from subsequent loadings. The later loading curves are generally used for assessing the mechanical properties of a tissue, and the first loading cycles, referred to as preconditioning, are omitted.

  10. Biological mechanisms underlying the role of physical fitness in health and resilience

    OpenAIRE

    Silverman, Marni N.; Deuster, Patricia A.

    2014-01-01

    Physical fitness, achieved through regular exercise and/or spontaneous physical activity, confers resilience by inducing positive psychological and physiological benefits, blunting stress reactivity, protecting against potentially adverse behavioural and metabolic consequences of stressful events and preventing many chronic diseases. In this review, we discuss the biological mechanisms underlying the beneficial effects of physical fitness on mental and physical health. Physical fitness appear...

  11. A Mechanism of Unidirectional Transformation, Leading to Antibiotic Resistance, Occurs within Nasopharyngeal Pneumococcal Biofilm Consortia.

    Science.gov (United States)

    Lattar, Santiago M; Wu, Xueqing; Brophy, Jennifer; Sakai, Fuminori; Klugman, Keith P; Vidal, Jorge E

    2018-05-15

    Streptococcus pneumoniae acquires genes for resistance to antibiotics such as streptomycin (Str) or trimethoprim (Tmp) by recombination via transformation of DNA released by other pneumococci and closely related species. Using naturally transformable pneumococci, including strain D39 serotype 2 (S2) and TIGR4 (S4), we studied whether pneumococcal nasopharyngeal transformation was symmetrical, asymmetrical, or unidirectional. Incubation of S2 Tet and S4 Str in a bioreactor simulating the human nasopharynx led to the generation of Spn Tet/Str recombinants. Double-resistant pneumococci emerged soon after 4 h postinoculation at a recombination frequency (rF) of 2.5 × 10 -4 while peaking after 8 h at a rF of 1.1 × 10 -3 Acquisition of antibiotic resistance genes by transformation was confirmed by treatment with DNase I. A high-throughput serotyping method demonstrated that all double-resistant pneumococci belonged to one serotype lineage (S2 Tet/Str ) and therefore that unidirectional transformation had occurred. Neither heterolysis nor availability of DNA for transformation was a factor for unidirectional transformation given that the density of each strain and extracellular DNA (eDNA) released from both strains were similar. Unidirectional transformation occurred regardless of the antibiotic-resistant gene carried by donors or acquired by recipients and regardless of whether competence-stimulating peptide-receptor cross talk was allowed. Moreover, unidirectional transformation occurred when two donor strains (e.g., S4 Str and S19F Tmp ) were incubated together, leading to S19F Str/Tmp but at a rF 3 orders of magnitude lower (4.9 × 10 -6 ). We finally demonstrated that the mechanism leading to unidirectional transformation was due to inhibition of transformation of the donor by the recipient. IMPORTANCE Pneumococcal transformation in the human nasopharynx may lead to the acquisition of antibiotic resistance genes or genes encoding new capsular variants

  12. Response to Jensen et al. : pelvic floor reconstruction with a biological mesh after extralevator abdominoperineal excision leads tolow wound complications and perineal hernia rates with minor movement limitations

    NARCIS (Netherlands)

    Musters, G. D.; Bemelman, W. A.; Tanis, P. J.

    2014-01-01

    Jensen et al describe their experience with reconstruction of the pelvic floor using a biological mesh after extralevator abdominoperineal excision (ELAPE)[1]. The title states that a biological mesh leads to low perineal wound complications and perineal hernia rates. Surprisingly the authors

  13. Enhancement mechanisms of graphene in nano-58S bioactive glass scaffold: mechanical and biological performance.

    Science.gov (United States)

    Gao, Chengde; Liu, Tingting; Shuai, Cijun; Peng, Shuping

    2014-04-16

    Graphene is a novel material and currently popular as an enabler for the next-generation nanocomposites. Here, we report the use of graphene to improve the mechanical properties of nano-58S bioactive glass for bone repair and regeneration. And the composite scaffolds were fabricated by a homemade selective laser sintering system. Qualitative and quantitative analysis demonstrated the successful incorporation of graphene into the scaffold without obvious structural damage and weight loss. The optimum compressive strength and fracture toughness reached 48.65 ± 3.19 MPa and 1.94 ± 0.10 MPa · m(1/2) with graphene content of 0.5 wt%, indicating significant improvements by 105% and 38% respectively. The mechanisms of pull-out, crack bridging, crack deflection and crack tip shielding were found to be responsible for the mechanical enhancement. Simulated body fluid and cell culture tests indicated favorable bioactivity and biocompatibility of the composite scaffold. The results suggest a great potential of graphene/nano-58S composite scaffold for bone tissue engineering applications.

  14. Shell and membrane theories in mechanics and biology from macro- to nanoscale structures

    CERN Document Server

    Mikhasev, Gennadi

    2015-01-01

    This book presents the latest results related to shells  characterize and design shells, plates, membranes and other thin-walled structures, a multidisciplinary approach from macro- to nanoscale is required which involves the classical disciplines of mechanical/civil/materials engineering (design, analysis, and properties) and physics/biology/medicine among others. The book contains contributions of a meeting of specialists (mechanical engineers, mathematicians, physicists and others) in such areas as classical and non-classical shell theories. New trends with respect to applications in mechanical, civil and aero-space engineering, as well as in new branches like medicine and biology are presented which demand improvements of the theoretical foundations of these theories and a deeper understanding of the material behavior used in such structures.

  15. Status on DEMO Helium Cooled Lithium Lead breeding blanket thermo-mechanical analyses

    Energy Technology Data Exchange (ETDEWEB)

    Aubert, J., E-mail: julien.aubert@cea.fr [CEA-Saclay, DEN, DM2S, F-91191 Gif-sur-Yvette (France); Aiello, G.; Jaboulay, J.-C. [CEA-Saclay, DEN, DM2S, F-91191 Gif-sur-Yvette (France); Kiss, B. [Institute of Nuclear Techniques, Budapest University of Technology and Economics, Budapest (Hungary); Morin, A. [CEA-Saclay, DEN, DM2S, F-91191 Gif-sur-Yvette (France)

    2016-11-01

    Highlights: • CEA with the support of Wigner-RCP and IPP-CR, is in charge of the design of the HCLL blanket for DEMO. The DEMO HCLL breeding blanket design capitalizes on the experience acquired on the HCLL Test Blanket Module designed for ITER. Design improvements are being implemented to adapt the design to DEMO specifications and performance objectives. • Thermal and mechanical analyses have been carried out in order to justify the design of the HCLL breeding blanket showing promising results for tie rods modules’ attachments system and relatively good behavior of the box in case of LOCA when comparing to RCC-MRx criteria. • CFD thermal analyses on generic breeding unit have enabled the consolidation of the results obtained with previous FEM design analyses. - Abstract: The EUROfusion Consortium develops a design of a fusion power demonstrator (DEMO) in the framework of the European “Horizon 2020” innovation and research program. One of the key components in the fusion reactor is the breeding blanket surrounding the plasma, ensuring tritium self-sufficiency, heat removal for conversion into electricity, and neutron shielding. The Helium Cooled Lithium Lead (HCLL) blanket is one of the concepts which is investigated for DEMO. It is made of a Eurofer structure and uses the eutectic liquid lithium–lead as tritium breeder and neutron multiplier, and helium gas as coolant. Within the EUROfusion organization, CEA with the support of Wigner-RCP and IPP-CR, is in charge of the design of the HCLL blanket for DEMO. This paper presents the status of the thermal and mechanical analyses carried out on the HCLL breeding blanket in order to justify the design. CFD thermal analyses on generic breeding unit including stiffening plates and cooling plates have been performed with ANSYS in order to consolidate results obtained with previous FEM design analyses. Moreover in order to expand the justification of the HCLL Breeding blanket design, the most loaded area of

  16. Electrical Transport Mechanisms and Photoconduction in Undoped Crystalline Flash-Evaporated Lead Iodide Thin Films

    Science.gov (United States)

    Al-Daraghmeh, Tariq M.; Saleh, Mahmoud H.; Ahmad, Mais Jamil A.; Bulos, Basim N.; Shehadeh, Khawla M.; Jafar, Mousa M. Abdul-Gader

    2018-03-01

    The flash-evaporation technique was utilized to fabricate undoped 1.35-μm and 1.2-μm thick lead iodide films at substrate temperatures T_{{s}} = 150 °C and 200°C, respectively. The films were deposited onto a coplanar comb-like copper (Cu-) electrode pattern, previously coated on glass substrates to form lateral metal-semiconductor-metal (MSM-) structures. The as-measured constant- temperature direct-current (dc)-voltage ( I( {V;T} ) - V ) curves of the obtained lateral coplanar Cu-PbI2-Cu samples (film plus electrode) displayed remarkable ohmic behavior at all temperatures ( T = 18 - 90°C). Their dc electrical resistance R_{{dc}} (T ) revealed a single thermally-activated conduction mechanism over the temperature range with activation energy E_{{act}} ≈ 0.90 - 0.98 {eV} , slightly less than half of room-temperature bandgap energy E_{{g}} ( ≈ 2.3 {eV} ) of undoped 2H-polytype PbI2 single crystals. The undoped flash-evaporated {PbI}_{{x}} thin films were homogeneous and almost stoichiometric ( x ≈ 1.87 ), in contrast to findings on lead iodide films prepared by other methods, and were highly crystalline hexagonal 2H-polytypic structure with c-axis perpendicular to the surface of substrates maintained at T_{s} ≳ 150°C. Photoconductivity measurements made on these lateral Cu-PbI2-Cu-structures under on-off visible-light illumination reveal a feeble photoresponse for long wavelengths ( λ > 570 {nm} ), but a strong response to blue light of photon energy E_{{ph}} ≈ 2.73 {eV} ( > E_{{g}} ), due to photogenerated electron-hole (e-h) pairs via direct band-to-band electronic transitions. The constant-temperature/dc voltage current-time I( {T,V} ) - t curves of the studied lateral PbI2 MSM-structures at low ambient temperatures ( T < 50°C), after cutting off the blue-light illumination, exhibit two trapping mechanisms with different relaxation times. These strongly depend on V and T , with thermally generated charge carriers in the PbI2 mask photogenerated

  17. Ionoregulatory disruption as the acute toxic mechanism for lead in the rainbow trout (Oncorhynchus mykiss)

    International Nuclear Information System (INIS)

    Rogers, J.T.; Richards, J.G.; Wood, C.M.

    2003-01-01

    The mechanism for acute toxicity of lead (Pb) in rainbow trout (Oncorhynchus mykiss) was investigated at Pb concentrations close to the 96 h LC50 of 1.0 mg dissolved Pb l -1 (0.8-1.4, 95% C.I.) determined in dechlorinated Hamilton city tap water (from Lake Ontario, hardness=140 mg l -1 CaCO 3 ). Tissue Pb accumulation associated with death was highest in the gill, followed by kidney and liver. Significant ionoregulatory impacts were observed in adult rainbow trout (200-300 g) fitted with indwelling dorsal aortic catheters and exposed to 1.1±0.04 mg dissolved Pb l -1 . Decreased plasma [Ca 2+ ], [Na + ] and [Cl - ] occurred after 48 h of exposure through to 120 h, with increases in plasma [Mg 2+ ], ammonia, and cortisol. No marked changes in PaO 2 , PaCO 2 , pH, glucose, or hematological parameters were evident. Branchial Na + /K + ATPase activity in juvenile trout exposed to concentrations close to the 96 h LC50 was inhibited by approximately 40% after 48 h of Pb exposure. Calcium ion flux measurements using 45 Ca as a radiotracer showed 65% inhibition of Ca 2+ influx after 0, 12, 24 or 48 h exposure to the 96 h LC50 concentration of Pb. There was also significant inhibition (40-50%) of both Na + and Cl - uptake, measured with 22 Na and 36 Cl simultaneously. We conclude that the mechanism of acute toxicity for Pb in rainbow trout occurs by ionoregulatory disruption rather than respiratory or acid/base distress at Pb concentrations close to the 96 h LC50 in moderately hard water

  18. Ionoregulatory disruption as the acute toxic mechanism for lead in the rainbow trout (Oncorhynchus mykiss)

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.T.; Richards, J.G.; Wood, C.M

    2003-07-16

    The mechanism for acute toxicity of lead (Pb) in rainbow trout (Oncorhynchus mykiss) was investigated at Pb concentrations close to the 96 h LC50 of 1.0 mg dissolved Pb l{sup -1} (0.8-1.4, 95% C.I.) determined in dechlorinated Hamilton city tap water (from Lake Ontario, hardness=140 mg l{sup -1} CaCO{sub 3}). Tissue Pb accumulation associated with death was highest in the gill, followed by kidney and liver. Significant ionoregulatory impacts were observed in adult rainbow trout (200-300 g) fitted with indwelling dorsal aortic catheters and exposed to 1.1{+-}0.04 mg dissolved Pb l{sup -1}. Decreased plasma [Ca{sup 2+}], [Na{sup +}] and [Cl{sup -}] occurred after 48 h of exposure through to 120 h, with increases in plasma [Mg{sup 2+}], ammonia, and cortisol. No marked changes in PaO{sub 2}, PaCO{sub 2}, pH, glucose, or hematological parameters were evident. Branchial Na{sup +}/K{sup +} ATPase activity in juvenile trout exposed to concentrations close to the 96 h LC50 was inhibited by approximately 40% after 48 h of Pb exposure. Calcium ion flux measurements using {sup 45}Ca as a radiotracer showed 65% inhibition of Ca{sup 2+} influx after 0, 12, 24 or 48 h exposure to the 96 h LC50 concentration of Pb. There was also significant inhibition (40-50%) of both Na{sup +} and Cl{sup -} uptake, measured with {sup 22}Na and {sup 36}Cl simultaneously. We conclude that the mechanism of acute toxicity for Pb in rainbow trout occurs by ionoregulatory disruption rather than respiratory or acid/base distress at Pb concentrations close to the 96 h LC50 in moderately hard water.

  19. Biologically inspired control and modeling of (biorobotic systems and some applications of fractional calculus in mechanics

    Directory of Open Access Journals (Sweden)

    Lazarević Mihailo P.

    2013-01-01

    Full Text Available In this paper, the applications of biologically inspired modeling and control of (biomechanical (nonredundant mechanisms are presented, as well as newly obtained results of author in mechanics which are based on using fractional calculus. First, it is proposed to use biological analog-synergy due to existence of invariant features in the execution of functional motion. Second, the model of (biomechanical system may be obtained using another biological concept called distributed positioning (DP, which is based on the inertial properties and actuation of joints of considered mechanical system. In addition, it is proposed to use other biological principles such as: principle of minimum interaction, which takes a main role in hierarchical structure of control and self-adjusting principle (introduce local positive/negative feedback on control with great amplifying, which allows efficiently realization of control based on iterative natural learning. Also, new, recently obtained results of the author in the fields of stability, electroviscoelasticity, and control theory are presented which are based on using fractional calculus (FC. [Projekat Ministarstva nauke Republike Srbije, br. 35006

  20. The prognosis of infective endocarditis treated with biological valves versus mechanical valves: A meta-analysis.

    Science.gov (United States)

    Tao, Ende; Wan, Li; Wang, WenJun; Luo, YunLong; Zeng, JinFu; Wu, Xia

    2017-01-01

    Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves. Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis. A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520). The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in the clinical features of patients

  1. Performance and mechanism for cadmium and lead adsorption from water and soil by corn straw biochar

    Institute of Scientific and Technical Information of China (English)

    Tong Chi; Jiane Zuo; Fenglin Liu

    2017-01-01

    Cadmium (Cd) and lead (Pb) in water and soil could be adsorbed by biochar produced fiom corn straw.Biochar pyrolyzed under 400℃ for 2 h could reach the ideal removal efficiencies (99.24% and 98.62% for Cd and Pb,respectively) from water with the biochar dosage of 20 g· L-1 and imtial concentration of 20 mg·L-1.The pH value of 4-7 was the optimal range for adsorption reaction.The adsorption mechanism was discussed on the basis of a range of characterizations,including X-ray diffraction (XRD),X-my photoelectron spectroscopy (XPS),Fourier transform infrared spectroscopy (FTIR) and Raman analysis;it was concluded as surface complexation with active sorption sites (-OH-COO-) coordination with π electrons (C =C,C =O) and precipitation with morganic anions (OH-,CO32-,SO42-) for both Cd and Pb.The sorption isotherms fit Langmuir model better than Freundlich model,and the saturated sorption capacities for Cd and Pb were 38.91 mg.g-1 and 28.99 mg· g-1,respectively.When mixed with soil,biochar could effectively increase alkalinity and reduce bioavailability of heavy metals.Thus,biochar derived from corn straw would be a green material for both removal of heavy metals and amelioration of soil.

  2. Planning and leading of the technological processes by mechanical working with microsoft project

    Science.gov (United States)

    Nae, I.; Grigore, N.

    2016-08-01

    Nowadays, fabrication systems and methods are being modified; new processing technologies come up, flow sheets develop a minimum number of phases, the flexibility of the technologies grows up, new methods and instruments of monitoring and leading the processing operations also come up. The technological course (route, entry, scheme, guiding) referring to the series of the operation, putting and execution phases of a mark in order to obtain the final product from the blank is represented by a sequence of activities realized by a logic manner, on a well determined schedule, with a determined budget and resources. Also, a project can be defined as a series of specific activities, methodical structured which they aim to finish a specific objective, within a fixed schedule and budget. Within the homogeneity between the project and the technological course, this research is presenting the defining of the technological course of mechanical chip removing process using Microsoft Project. Under these circumstances, this research highlights the advantages of this method: the celerity using of other technological alternatives in order to pick the optimal process, the job scheduling being constrained by any kinds, the standardization of some processing technological operations.

  3. Conceptual design of the blanket mechanical attachment for the helium-cooled lithium-lead reactor

    International Nuclear Information System (INIS)

    Barrera, G.; Branas, B.; Lucas, J.; Doncel, J.; Medrano, M.; Garcia, A.; Giancarli, L.; Ibarra, A.; Li Puma, A.; Maisonnier, D.; Sardain, P.

    2008-01-01

    The conceptual design of a new type of fusion reactor based on the helium-cooled lithium-lead (HCLL) blanket has been performed within the European Power Plant Conceptual Studies. As part of this activity, a new attachment system suitable for the HCLL blanket modules had to be developed. This attachment is composed of two parts. The first one is the connection between module and the first part of a shield, called high temperature shield, which operates at a temperature around 500 deg. C, close to that of the blanket module. This connection must be made at the lateral walls, in order to avoid openings through the first wall and breeding zone thus avoiding complex design and fabrication issues of the module. The second connection is the one between the high temperature shield and a second shield called low temperature shield, which has a temperature during reactor operation around 150 deg. C. The design of this connection is complex because it must allow the large differential thermal expansion (up to 30 mm) between the two components. Design proposals for both connections are presented, together with the results of finite element mechanical analyses which demonstrate the feasibility to support the blanket and shield modules during normal and accidental operation conditions

  4. Study and understanding of the ageing mechanisms in lead-calcium alloys

    International Nuclear Information System (INIS)

    Rossi, F.

    2006-12-01

    The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

  5. Highly Efficient Lead Distribution by Magnetic Sewage Sludge Biochar: Sorption Mechanisms and Bench Applications.

    Science.gov (United States)

    Ifthikar, Jerosha; Wang, Jia; Wang, Qiliang; Wang, Ting; Wang, Huabin; Khan, Aimal; Jawad, Ali; Sun, Tingting; Jiao, Xiang; Chen, Zhuqi

    2017-08-01

    Highly efficient magnetic sewage sludge biochar (MSSBC) discloses feasible fabrication process with lower production cost, superior adsorption capacity, usage of waste sewage sludge as resource, selected by external magnetic field and exceptional regeneration property. 2gL -1 MSSBC exhibited a high adsorption capacity of 249.00mgg -1 in 200ppmPb(II) and the lead-MSSBC equilibrium was achieved within one hour, owing to the existence of the copious active sites. The adsorption kinetics was well described by the pseudo-second-order model while the adsorption isotherm could be fitted by Langmuir model. Mechanism study demonstrated the adsorption involved electrostatic attraction, ion exchange, inner-sphere complexation and formation of co-precipitates at the surface of MSSBC. Additionally, adsorption performance maintained remarkable in a broad pH window. These outcomes demonstrated the promising waste resource utilization by a feasible approach that turns the solid waste of sewage sludge into biochar adsorbent with auspicious applications in elimination of Pb(II) from wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Mechanism of Water Droplet Breakup Near the Leading Edge of an Airfoil

    Science.gov (United States)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida, Garcia

    2012-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 microns, and airfoil velocities of 70 and 90 m/sec.

  7. A Model of How Different Biology Experts Explain Molecular and Cellular Mechanisms

    Science.gov (United States)

    Trujillo, Caleb M.; Anderson, Trevor R.; Pelaez, Nancy J.

    2015-01-01

    Constructing explanations is an essential skill for all science learners. The goal of this project was to model the key components of expert explanation of molecular and cellular mechanisms. As such, we asked: What is an appropriate model of the components of explanation used by biology experts to explain molecular and cellular mechanisms? Do explanations made by experts from different biology subdisciplines at a university support the validity of this model? Guided by the modeling framework of R. S. Justi and J. K. Gilbert, the validity of an initial model was tested by asking seven biologists to explain a molecular mechanism of their choice. Data were collected from interviews, artifacts, and drawings, and then subjected to thematic analysis. We found that biologists explained the specific activities and organization of entities of the mechanism. In addition, they contextualized explanations according to their biological and social significance; integrated explanations with methods, instruments, and measurements; and used analogies and narrated stories. The derived methods, analogies, context, and how themes informed the development of our final MACH model of mechanistic explanations. Future research will test the potential of the MACH model as a guiding framework for instruction to enhance the quality of student explanations. PMID:25999313

  8. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    Science.gov (United States)

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44 + , αSMA + , Vimentin + and CD105 - human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Characterization of mechanical and biological properties of 3-D scaffolds reinforced with zinc oxide for bone tissue engineering.

    Directory of Open Access Journals (Sweden)

    Pei Feng

    Full Text Available A scaffold for bone tissue engineering should have highly interconnected porous structure, appropriate mechanical and biological properties. In this work, we fabricated well-interconnected porous β-tricalcium phosphate (β-TCP scaffolds via selective laser sintering (SLS. We found that the mechanical and biological properties of the scaffolds were improved by doping of zinc oxide (ZnO. Our data showed that the fracture toughness increased from 1.09 to 1.40 MPam(1/2, and the compressive strength increased from 3.01 to 17.89 MPa when the content of ZnO increased from 0 to 2.5 wt%. It is hypothesized that the increase of ZnO would lead to a reduction in grain size and an increase in density of the strut. However, the fracture toughness and compressive strength decreased with further increasing of ZnO content, which may be due to the sharp increase in grain size. The biocompatibility of the scaffolds was investigated by analyzing the adhesion and the morphology of human osteoblast-like MG-63 cells cultured on the surfaces of the scaffolds. The scaffolds exhibited better and better ability to support cell attachment and proliferation when the content of ZnO increased from 0 to 2.5 wt%. Moreover, a bone like apatite layer formed on the surfaces of the scaffolds after incubation in simulated body fluid (SBF, indicating an ability of osteoinduction and osteoconduction. In summary, interconnected porous β-TCP scaffolds doped with ZnO were successfully fabricated and revealed good mechanical and biological properties, which may be used for bone repair and replacement potentially.

  10. Mechanical-biological waste conditioning with controlled venting - the Meisenheim mechanical-biological waste conditioning plant; Mechanisch-biologische Restabfallbehandlung nach dem Kaminzugverfahren - MBRA Meisenheim

    Energy Technology Data Exchange (ETDEWEB)

    Hangen, H.O. [Abfallwirtschaftsbetrieb Landkreis Bad Kreuznach, Bad Kreuznach (Germany)

    1998-12-31

    The decision of the rural district of Bad Kreuznach to propose creating facilities for mechanical-biological waste conditioning at the new northern Meisenheim landfill was consistent and correct. It will ensure that the material deposited at this new, state-of-the-art landfill is organically `lean` and can be deposited with a high density. Preliminary sifting of the material prior to depositing safeguards that no improper components are inadvertently included. Three years of operation warrant the statement that waste components that cannot be appropriately biologically conditioned should be eliminated prior to rotting. (orig.) [Deutsch] Die Entscheidung des Landkreises Bad Kreuznach, der neu eingerichteten Norddeponie Meisenheim eine MBRA vorzuschlaten, war auf jeden Fall konsequent und richtig. Es ist damit sicher gestellt, dass in diesem neuen nach dem Stand der Technik eingerichteten Deponiebereich von Anfang an ein Material eingelagert wird, das `organisch abgemagert` ist und mit hoher Einbaudichte eingebaut werden kann. Die Sichtung des gesamten Deponie-Inputs in der Vorsortierhalle gibt ein Stueck Sicherheit, dass keine nicht zugelassenen Stoffe verdeckt dem Ablagerungsbereich der Deponie zugefuehrt werden. Nach mehr als 3 Jahren Betriebszeit kann festgestellt werden, dass biologisch nicht sinnvoll behandelbare Abfallbestandteile vor dem Rotteprozess abgetrennt werden sollten. (orig.)

  11. Exploring the MACH Model's Potential as a Metacognitive Tool to Help Undergraduate Students Monitor Their Explanations of Biological Mechanisms

    Science.gov (United States)

    Trujillo, Caleb M.; Anderson, Trevor R.; Pelaez, Nancy J.

    2016-01-01

    When undergraduate biology students learn to explain biological mechanisms, they face many challenges and may overestimate their understanding of living systems. Previously, we developed the MACH model of four components used by expert biologists to explain mechanisms: Methods, Analogies, Context, and How. This study explores the implementation of…

  12. Solid recovered fuel production through the mechanical-biological treatment of wastes

    OpenAIRE

    Velis, C. A.

    2010-01-01

    This thesis is concerned with the production of solid recovered fuel (SRF) from municipal solid waste using mechanical biological treatment (MBT) plants. It describes the first in-depth analysis of a UK MBT plant and addresses the fundamental research question: are MBT plants and their unit operations optimised to produce high quality SRF in the UK? A critical review of the process science and engineering of MBT provides timely insights into the quality management and standa...

  13. Stress Biology and Aging Mechanisms: Toward Understanding the Deep Connection Between Adaptation to Stress and Longevity

    OpenAIRE

    Epel, Elissa S.; Lithgow, Gordon J.

    2014-01-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress (“hormetic stress”). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses (“toxic stress”) and shorten lifespan. One key question is whether the str...

  14. Influences of mechanical pretreatment on the non-biological treatment of municipal wastewater by forward osmosis.

    Science.gov (United States)

    Hey, Tobias; Zarebska, Agata; Bajraktari, Niada; Vogel, Jörg; Hélix-Nielsen, Claus; la Cour Jansen, Jes; Jönsson, Karin

    2017-09-01

    Municipal wastewater treatment involves mechanical, biological and chemical treatment steps for protecting the environment from adverse effects. The biological treatment step consumes the most energy and can create greenhouse gases. This study investigates municipal wastewater treatment without the biological treatment step, including the effects of different pretreatment configurations, for example, direct membrane filtration before forward osmosis. Forward osmosis was tested using raw wastewater and wastewater subjected to different types of mechanical pretreatment, for example, microsieving and microfiltration permeation, as a potential technology for municipal wastewater treatment. Forward osmosis was performed using Aquaporin Inside™ and Hydration Technologies Inc. (HTI) membranes with NaCl as the draw solution. Both types of forward osmosis membranes were tested in parallel for the different types of pretreated feed and evaluated in terms of water flux and solute rejection, that is, biochemical oxygen demand (BOD 7 ) and total and soluble phosphorus contents. The Aquaporin and HTI membranes achieved a stable water flux with rejection rates of more than 96% for BOD 7 and total and soluble phosphorus, regardless of the type of mechanical pretreated wastewater considered. This result indicates that forward osmosis membranes can tolerate exposure to municipal waste water and that the permeate can fulfil the Swedish discharge limits.

  15. Behavior of selected organic pollutants in municipal waste during the mechanical-biological progress of composting

    International Nuclear Information System (INIS)

    Drahosch, W.

    1998-06-01

    Municipal waste was investigated during the mechanical-biological process of composting. Waste from Burgenland is treated mechanically and biologically to reduce organic matter in the material and to keep gas building potential low before deposition. Samples were taken and analyzed during a period of 80 days. The parameters: temperature, dry-weight, glow loss, ammonium, nitrate and phenolic substances were measured to follow the composting process. It was found that the process was almost finished after a period of 40 days in which the material was breathed intensively. The content of polycyclic aromatic hydrocarbons and polychlorinated phenols decreased slightly. It was not clear whether this was due to microbiological activity or blowing-out effects. Polychlorinated biphenyls were found to be stable during composting. The concentrations were considered as high. Hepta- and octachlorinated dibenzodioxines were formed during the first 10 days. The increase of octachlorinated dibenzodioxin was threefold. Other dioxines and furanes remained unchanged. Finally it was found out that mechanical-biological waste treatment is insufficient in order to reduce organic pollutants effectively. (author)

  16. Borderline personality disorder and childhood trauma: exploring the affected biological systems and mechanisms.

    Science.gov (United States)

    Cattane, Nadia; Rossi, Roberta; Lanfredi, Mariangela; Cattaneo, Annamaria

    2017-06-15

    According to several studies, the onset of the Borderline Personality Disorder (BPD) depends on the combination between genetic and environmental factors (GxE), in particular between biological vulnerabilities and the exposure to traumatic experiences during childhood. We have searched for studies reporting possible alterations in several biological processes and brain morphological features in relation to childhood trauma experiences and to BPD. We have also looked for epigenetic mechanisms as they could be mediators of the effects of childhood trauma in BPD vulnerability. We prove the role of alterations in Hypothalamic-Pituitary-Adrenal (HPA) axis, in neurotrasmission, in the endogenous opioid system and in neuroplasticity in the childhood trauma-associated vulnerability to develop BPD; we also confirm the presence of morphological changes in several BPD brain areas and in particular in those involved in stress response. Not so many studies are available on epigenetic changes in BPD patients, although these mechanisms are widely investigated in relation to stress-related disorders. A better comprehension of the biological and epigenetic mechanisms, affected by childhood trauma and altered in BPD patients, could allow to identify "at high risk" subjects and to prevent or minimize the development of the disease later in life.

  17. Lead titanate nanotubes synthesized via ion-exchange method: Characteristics and formation mechanism

    International Nuclear Information System (INIS)

    Song Liang; Cao Lixin; Li Jingyu; Liu Wei; Zhang Fen; Zhu Lin; Su Ge

    2011-01-01

    Highlights: → Lead titanate nanotubes PbTi 3 O 7 were firstly synthesized by ion-exchange method. → Sodium titanate nanotubes have ion exchangeability. → Lead titanate nanotubes show a distinct red shift on absorption edge. - Abstract: A two-step method is presented for the synthesis of one dimensional lead titanate (PbTi 3 O 7 ) nanotubes. Firstly, titanate nanotubes were prepared by an alkaline hydrothermal process with TiO 2 nanopowder as precursor, and then lead titanate nanotubes were formed through an ion-exchange reaction. We found that sodium titanate nanotubes have ion exchangeability with lead ions, while protonated titanate nanotubes have not. For the first time, we distinguished the difference between sodium titanate nanotubes and protonated titanate nanotubes in the ion-exchange process, which reveals a layer space effect of nanotubes in the ion-exchange reaction. In comparison with sodium titanate, the synthesized lead titanate nanotubes show a narrowed bandgap.

  18. Thermodynamic modeling of transcription: sensitivity analysis differentiates biological mechanism from mathematical model-induced effects.

    Science.gov (United States)

    Dresch, Jacqueline M; Liu, Xiaozhou; Arnosti, David N; Ay, Ahmet

    2010-10-24

    Quantitative models of gene expression generate parameter values that can shed light on biological features such as transcription factor activity, cooperativity, and local effects of repressors. An important element in such investigations is sensitivity analysis, which determines how strongly a model's output reacts to variations in parameter values. Parameters of low sensitivity may not be accurately estimated, leading to unwarranted conclusions. Low sensitivity may reflect the nature of the biological data, or it may be a result of the model structure. Here, we focus on the analysis of thermodynamic models, which have been used extensively to analyze gene transcription. Extracted parameter values have been interpreted biologically, but until now little attention has been given to parameter sensitivity in this context. We apply local and global sensitivity analyses to two recent transcriptional models to determine the sensitivity of individual parameters. We show that in one case, values for repressor efficiencies are very sensitive, while values for protein cooperativities are not, and provide insights on why these differential sensitivities stem from both biological effects and the structure of the applied models. In a second case, we demonstrate that parameters that were thought to prove the system's dependence on activator-activator cooperativity are relatively insensitive. We show that there are numerous parameter sets that do not satisfy the relationships proferred as the optimal solutions, indicating that structural differences between the two types of transcriptional enhancers analyzed may not be as simple as altered activator cooperativity. Our results emphasize the need for sensitivity analysis to examine model construction and forms of biological data used for modeling transcriptional processes, in order to determine the significance of estimated parameter values for thermodynamic models. Knowledge of parameter sensitivities can provide the necessary

  19. Examples of processing problematic waste and material. A-3. Processing of lead by mechanical decontamination at UKAEA Harwell

    International Nuclear Information System (INIS)

    2006-01-01

    The UKAEA and its contractor (NNC) have decontaminated lead blocks arising from the decommissioning of a metallurgical site that comprised three concrete shielded remote handling cells and 36 lead shielded enclosures. The primary decommissioning and dismantling work entailed the dismantling of the 36 lead enclosures, which were expected to yield over 1000 t of lead shielding bricks as waste. During the initial dismantling of the lead shielded enclosures, all the lead bricks were monitored for radioactive contamination; clean items were segregated and set aside for detailed clearance and assurance checks. The contaminated blocks were sent for assessment and decontamination treatment, as necessary. The decontamination process utilized a purpose built partitioned containment tent, ventilated with a HEPA filtration system, so that the receipt, decontamination and radiological monitoring of individual items could be segregated in order to minimize any cross-contamination. The dismantled lead blocks comprised a range of standard thicknesses (2, 4, 9 and 10 in, or 3, 8, 13 and 15 cm) and incorporated a variety of chevron, concave and convex shapes, which are utilized to avoid weaknesses within the assembled shielding. The primary technical issues for the mechanical processing of the contaminated lead blocks were consideration of the individual lead brick shapes (i.e. the bricks were contoured) and the individual weight of the bricks, which had a range of 10-75 kg. The preferred option was a manual dry cutting technique using a handheld rotary industrial planer (the selected planer is normally associated with the joinery trade). The dry cutting option considered the malleability of the lead, which under certain circumstances during dry cutting could give rise to localized heating effects, leading to melted lead over the cutting surface, resulting in limited effectiveness in the removal of the contaminated layer. To mitigate this effect the planer was set to take cuts

  20. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators; Bleitellurid mit erhoehter mechanischer Stabilitaet fuer zylindrische thermoelektrische Generatoren

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Andreas

    2013-04-30

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb{sub 1-x}Ca{sub x}Te were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while its thermoelectric

  1. Lead telluride with increased mechanical stability for cylindrical thermoelectric generators; Bleitellurid mit erhoehter mechanischer Stabilitaet fuer zylindrische thermoelektrische Generatoren

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Andreas

    2013-04-30

    The aim of this work is to improve the mechanical stability of lead telluride (PbTe), trying to vary its mechanical properties independently from its thermoelectric properties. Thus the influence of material preparation as well as different dopants on the mechanical and thermoelectric properties of lead telluride is being analysed. When using appropriately set process parameters, milling and sintering of lead telluride increases the material's hardness. With sintering temperatures exceeding 300 C stable material of high relative density can be achieved. Milling lead telluride generates lattice defects leading to a reduction of the material's charge carrier density. These defects can be reduced by increased sintering temperatures. Contamination of the powder due to the milling process leads to bloating during thermal cycling and thus reduced density of the sintered material. In addition to that, evaporation of tellurium at elevated temperatures causes instability of the material's thermoelectric properties. Based on the experimental results obtained in this work, the best thermoelectric and mechanical properties can be obtained by sintering coarse powders at around 400 C. Within this work a concept was developed to vary the mechanical properties of lead telluride via synthesis of PbTe with electrically nondoping elements, which thus may keep the thermoelectric properties unchanged. Therefore, the mechanical and thermoelectric properties of Pb{sub 1-x}Ca{sub x}Te were investigated. Doping pure PbTe with calcium causes a significant increase of the material's hardness while only slightly decreasing the charge carrier density and thus keeping the thermoelectric properties apart from a slight reduction of the electrical conductivity nearly unchanged. The abovementioned concept is proven using sodium doped lead telluride, as it is used for thermoelectric generators: The additional doping with calcium again increases the material's hardness while

  2. Mechanical and fatigue properties of martensitic 20X13 and austenitic 12X18H10T at interaction with lead nad lead-bismuth melts

    International Nuclear Information System (INIS)

    Yas'kiv, O.I.; Fedirko, V.M.

    2013-01-01

    The effect of Pb and Pb-Bi melts on mechanical properties and fatigue of Fe-13Cr and Fe-18Cr-10Ni-Ti steels in temperature interval 250...750 deg C has been investigated. It was shown that metal melts lead to increasing of strength of Fe-13Cr steel on 10...20 % as compared with vacuum and this effect increases with temperature rising. Fe-13Cr steel is prone to liquid metal embrittlement in temperature interval 350...450 deg C, particularly in Pb-Bi melt. Mechanical properties of Fe-18Cr-10Ni-Ti are not affected by metal melts. Both Pb and Pb-Bi assist in reducing of fatigue life of steels and this effect is more significant in Pb-Bi

  3. Lead exposure and biological effects in pied flycatchers (Ficedula hypoleuca) before and after the closure of a lead mine in northern Sweden

    International Nuclear Information System (INIS)

    Berglund, A.M.M.; Ingvarsson, P.K.; Danielsson, H.; Nyholm, N.E.I.

    2010-01-01

    Mining activities affect the surrounding environment by increasing exposure to metals. In this study, metal accumulation and its effects on reproduction and health of pied flycatcher (Ficedula hypoleuca) nestlings were monitored before and up to five years after a lead mine and enrichment plant closed down. The lead concentration in moss, nestling blood, liver and feces all indicated decreased lead exposure by at least 31% after closure, although only blood lead decreased significantly. Although the birds responded fairly well to the changed atmospheric deposition (based on moss samples), concentrations were still higher compared with birds in a reference area, and breeding was affected at the mine (smaller clutches and higher mortality). Surviving nestlings suffered from lower hemoglobin levels, mean cell hemoglobin concentrations and inhibited δ-aminolevulinic acid dehydratase activity. Lead poisoning contributed to poor health and adverse reproductive effects, but other factors (e.g. increased parasitic load) probably also affected the birds. - Increased mortality and lower blood values in pied flycatcher (Ficedula hypoleuca) nestlings near a closed lead mine.

  4. ONE PROBABLE MECHANISM OF THE LEARNING-MEMORY DAMAGE BY LEAD: THE CHANGES OF NOS IN HIPPOCAMPUS

    Institute of Scientific and Technical Information of China (English)

    王静; 赵义; 杨章民; 张进; 李积胜; 司履生; 王一理

    2003-01-01

    Objective To study the effects of lead on the activity and expression of nitric oxide synthase (NOS) and relationship between the effects of lead on learning-memory and changes of NOS in subfields of hippocampus. Methods Y-maze test was used to study the effects of lead on ability of learning-memory; NADPH-d histochemistry and immunohistochemistry methods were used to investigate the changes of NOS in subfields of hippocampus. Results Compared with the control group, the ability of learning- memory in lead-exposed rats was significantly decreased (P<0.05); the number of NOS positive neurons in CA1 region and dentate gyrus of lead-exposed rats was significantly decreased(P<0.05), but no marked changes in CA3 region; the number of nNOS positive neurons in CA1 of lead-exposed rats was also significantly decreased(P<0.05), but no obvious changes in CA3. Conclusion Lead could damage the ability of learning-memory in rats. Lead could decrease the activity and expression of NOS in hippocampus and had different effects on NOS in different subfields of hippocampus. The changes of NOS in hippocampus induced by lead may be the mechanism of the learning-memory damage by lead.

  5. Features of Knowledge Building in Biology: Understanding Undergraduate Students' Ideas about Molecular Mechanisms.

    Science.gov (United States)

    Southard, Katelyn; Wince, Tyler; Meddleton, Shanice; Bolger, Molly S

    2016-01-01

    Research has suggested that teaching and learning in molecular and cellular biology (MCB) is difficult. We used a new lens to understand undergraduate reasoning about molecular mechanisms: the knowledge-integration approach to conceptual change. Knowledge integration is the dynamic process by which learners acquire new ideas, develop connections between ideas, and reorganize and restructure prior knowledge. Semistructured, clinical think-aloud interviews were conducted with introductory and upper-division MCB students. Interviews included a written conceptual assessment, a concept-mapping activity, and an opportunity to explain the biomechanisms of DNA replication, transcription, and translation. Student reasoning patterns were explored through mixed-method analyses. Results suggested that students must sort mechanistic entities into appropriate mental categories that reflect the nature of MCB mechanisms and that conflation between these categories is common. We also showed how connections between molecular mechanisms and their biological roles are part of building an integrated knowledge network as students develop expertise. We observed differences in the nature of connections between ideas related to different forms of reasoning. Finally, we provide a tentative model for MCB knowledge integration and suggest its implications for undergraduate learning. © 2016 K. Southard et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). 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).

  6. Different mechanisms for lead acetate, aluminum and cadmium sulfate in rat corpus cavernosum

    International Nuclear Information System (INIS)

    Senbel, Amira M.; Saad, Evan I.; Taha, Safaa S.; Mohamed, Hosny F.

    2016-01-01

    Introduction: Some heavy metals show adverse vascular and neurological effects, however, their effect on erection is underestimated. This study aims to investigate the effect of Pb, Cd and Al on erectile function and their potential mechanism of action in rats. Methods: Measurement of intracavernosal pressure/mean arterial pressure (ICP/MAP) changes elicited by electrical stimulation of cavernous nerve in anesthetized rats treated with Pb-acetate, Al-sulfate, or Cd-sulfate acutely, and subacutely for 7 days. Serum creatinine, testosterone, TBARs, GSH levels and metal accumulation in corpus cavernosum were measured. Results: Pb, Al and Cd significantly reduced ICP/MAP in rats after acute (2,10–2,10 and 1,3 mg/kg respectively) and sub-acute (3, 3, and 1 mg/kg/day respectively) treatments. They selectively accumulated in the corpus cavernosum reaching 25.107 ± 2.081 μg/g wet weight for Pb, 1.029 ± 0.193 for Cd, 31.343 ± 1.991 for Al, compared to 7.084 ± 1.517, 0.296 ± 0.067, and 8.86 ± 1.115 as controls respectively. Serum creatinine levels were not altered. Cd and Al significantly reduced testosterone level to 0.483 ± 0.059 and 0.419 ± 0.037 ng/ml respectively compared to 0.927 ± 0.105 ng/ml as control. Aluminum elevated TBARs significantly by 27.843%. The acute anti-erectile action of Pb was blocked by non-selective NOS and GC inhibitors and potassium channel blocker. Lead also masked the potentiatory effect of L-arginine and diazoxide on ICP/MAP. No interaction with muscarinic or nicotinic modulators was observed. Conclusions: Pb, Cd and Al show anti-erectile effect independent on renal injury. They don not modulate cholinergic nor ganglionic transmission in corpus cavernosum. Pb may inhibit NO/cGMP/K + channel pathway. The effect of Cd and Al but not Pb seems to be hormonal dependent.

  7. Urban gardens: lead exposure, recontamination mechanisms, and implications for remediation design.

    Science.gov (United States)

    Clark, Heather F; Hausladen, Debra M; Brabander, Daniel J

    2008-07-01

    Environmental lead contamination is prevalent in urban areas where soil represents a significant sink and pathway of exposure. This study characterizes the speciation of lead that is relevant to local recontamination and to human exposure in the backyard gardens of Roxbury and Dorchester, MA, USA. One hundred forty-one backyard gardens were tested by X-ray fluorescence, and 81% of gardens have lead levels above the US EPA action limit of 400 microg/g. Raised gardening beds are the in situ exposure reduction method used in the communities to promote urban gardening. Raised beds were tested for lead and the results showed that the lead concentration increased from an initial range of 150+/-40 microg/g to an average of 336 microg/g over 4 years. The percent distribution of lead in the fine grain soil (lead, and the trace metal signature of the fine grain soil in both gardens and raised gardening beds is characteristic of lead-based paint. This study demonstrates that raised beds are a limited exposure reduction method and require maintenance to achieve exposure reduction goals. An exposure model was developed based on a suite of parameters that combine relevant values from the literature with site-specific quantification of exposure pathways. This model suggests that consumption of homegrown produce accounts for only 3% of children's daily exposure of lead while ingestion of fine grained soil (lead remediation on a yard-by-yard scale requires constant maintenance and that remediation may need to occur on a neighborhood-wide scale.

  8. A MODELING AND SIMULATION LANGUAGE FOR BIOLOGICAL CELLS WITH COUPLED MECHANICAL AND CHEMICAL PROCESSES.

    Science.gov (United States)

    Somogyi, Endre; Glazier, James A

    2017-04-01

    Biological cells are the prototypical example of active matter. Cells sense and respond to mechanical, chemical and electrical environmental stimuli with a range of behaviors, including dynamic changes in morphology and mechanical properties, chemical uptake and secretion, cell differentiation, proliferation, death, and migration. Modeling and simulation of such dynamic phenomena poses a number of computational challenges. A modeling language describing cellular dynamics must naturally represent complex intra and extra-cellular spatial structures and coupled mechanical, chemical and electrical processes. Domain experts will find a modeling language most useful when it is based on concepts, terms and principles native to the problem domain. A compiler must then be able to generate an executable model from this physically motivated description. Finally, an executable model must efficiently calculate the time evolution of such dynamic and inhomogeneous phenomena. We present a spatial hybrid systems modeling language, compiler and mesh-free Lagrangian based simulation engine which will enable domain experts to define models using natural, biologically motivated constructs and to simulate time evolution of coupled cellular, mechanical and chemical processes acting on a time varying number of cells and their environment.

  9. Biological mechanisms discriminating growth rate and adult body weight phenotypes in two Chinese indigenous chicken breeds.

    Science.gov (United States)

    Dou, Tengfei; Zhao, Sumei; Rong, Hua; Gu, Dahai; Li, Qihua; Huang, Ying; Xu, Zhiqiang; Chu, Xiaohui; Tao, Linli; Liu, Lixian; Ge, Changrong; Te Pas, Marinus F W; Jia, Junjing

    2017-06-20

    Intensive selection has resulted in increased growth rates and muscularity in broiler chickens, in addition to adverse effects, including delayed organ development, sudden death syndrome, and altered metabolic rates. The biological mechanisms underlying selection responses remain largely unknown. Non-artificially-selected indigenous Chinese chicken breeds display a wide variety of phenotypes, including differential growth rate, body weight, and muscularity. The Wuding chicken breed is a fast growing large chicken breed, and the Daweishan mini chicken breed is a slow growing small chicken breed. Together they form an ideal model system to study the biological mechanisms underlying broiler chicken selection responses in a natural system. The objective of this study was to study the biological mechanisms underlying differential phenotypes between the two breeds in muscle and liver tissues, and relate these to the growth rate and body development phenotypes of the two breeds. The muscle tissue in the Wuding breed showed higher expression of muscle development genes than muscle tissue in the Daweishan chicken breed. This expression was accompanied by higher expression of acute inflammatory response genes in Wuding chicken than in Daweishan chicken. The muscle tissue of the Daweishan mini chicken breed showed higher expression of genes involved in several metabolic mechanisms including endoplasmic reticulum, protein and lipid metabolism, energy metabolism, as well as specific immune traits than in the Wuding chicken. The liver tissue showed fewer differences between the two breeds. Genes displaying higher expression in the Wuding breed than in the Daweishan breed were not associated with a specific gene network or biological mechanism. Genes highly expressed in the Daweishan mini chicken breed compared to the Wuding breed were enriched for protein metabolism, ABC receptors, signal transduction, and IL6-related mechanisms. We conclude that faster growth rates and larger

  10. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 1 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate

  11. Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Steven; Juanes, Ruben

    2011-12-31

    In this project we have sought to explain the co-existence of gas and hydrate phases in sediments within the gas hydrate stability zone. We have focused on the gas/brine interface at the scale of individual grains in the sediment. The capillary forces associated with a gas/brine interface play a dominant role in many processes that occur in the pores of sediments and sedimentary rocks. The mechanical forces associated with the same interface can lead to fracture initiation and propagation in hydrate-bearing sediments. Thus the unifying theme of the research reported here is that pore scale phenomena are key to understanding large scale phenomena in hydrate-bearing sediments whenever a free gas phase is present. Our analysis of pore-scale phenomena in this project has delineated three regimes that govern processes in which the gas phase pressure is increasing: fracturing, capillary fingering and viscous fingering. These regimes are characterized by different morphology of the region invaded by the gas. On the other hand when the gas phase pressure is decreasing, the corresponding regimes are capillary fingering and compaction. In this project, we studied all these regimes except compaction. Many processes of interest in hydrate-bearing sediments can be better understood when placed in the context of the appropriate regime. For example, hydrate formation in sub-permafrost sediments falls in the capillary fingering regime, whereas gas invasion into ocean sediments is likely to fall into the fracturing regime. Our research provides insight into the mechanisms by which gas reservoirs are converted to hydrate as the base of the gas hydrate stability zone descends through the reservoir. If the reservoir was no longer being charged, then variation in grain size distribution within the reservoir explain hydrate saturation profiles such as that at Mt. Elbert, where sand-rich intervals containing little hydrate are interspersed between intervals containing large hydrate

  12. In search of mitochondrial mechanisms: interfield excursions between cell biology and biochemistry.

    Science.gov (United States)

    Bechtel, William; Abrahamsen, Adele

    2007-01-01

    Developing models of biological mechanisms, such as those involved in respiration in cells, often requires collaborative effort drawing upon techniques developed and information generated in different disciplines. Biochemists in the early decades of the 20th century uncovered all but the most elusive chemical operations involved in cellular respiration, but were unable to align the reaction pathways with particular structures in the cell. During the period 1940-1965 cell biology was emerging as a new discipline and made distinctive contributions to understanding the role of the mitochondrion and its component parts in cellular respiration. In particular, by developing techniques for localizing enzymes or enzyme systems in specific cellular components, cell biologists provided crucial information about the organized structures in which the biochemical reactions occurred. Although the idea that biochemical operations are intimately related to and depend on cell structures was at odds with the then-dominant emphasis on systems of soluble enzymes in biochemistry, a reconceptualization of energetic processes in the 1960s and 1970s made it clear why cell structure was critical to the biochemical account. This paper examines how numerous excursions between biochemistry and cell biology contributed a new understanding of the mechanism of cellular respiration.

  13. Electro-mechanical response of a 3D nerve bundle model to mechanical loads leading to axonal injury.

    Science.gov (United States)

    Cinelli, I; Destrade, M; Duffy, M; McHugh, P

    2018-03-01

    Traumatic brain injuries and damage are major causes of death and disability. We propose a 3D fully coupled electro-mechanical model of a nerve bundle to investigate the electrophysiological impairments due to trauma at the cellular level. The coupling is based on a thermal analogy of the neural electrical activity by using the finite element software Abaqus CAE 6.13-3. The model includes a real-time coupling, modulated threshold for spiking activation, and independent alteration of the electrical properties for each 3-layer fibre within a nerve bundle as a function of strain. Results of the coupled electro-mechanical model are validated with previously published experimental results of damaged axons. Here, the cases of compression and tension are simulated to induce (mild, moderate, and severe) damage at the nerve membrane of a nerve bundle, made of 4 fibres. Changes in strain, stress distribution, and neural activity are investigated for myelinated and unmyelinated nerve fibres, by considering the cases of an intact and of a traumatised nerve membrane. A fully coupled electro-mechanical modelling approach is established to provide insights into crucial aspects of neural activity at the cellular level due to traumatic brain injury. One of the key findings is the 3D distribution of residual stresses and strains at the membrane of each fibre due to mechanically induced electrophysiological impairments, and its impact on signal transmission. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Lead generation strategy as a multichannel mechanism of growth of a modern enterprise

    Directory of Open Access Journals (Sweden)

    Łukowski Wojciech

    2016-09-01

    Full Text Available Lead generation strategy describes the marketing process of involvement and capture of interest in a product or service which is aimed at developing sales plans and, as a consequence, soliciting new clients. Lead generation is becoming an increasingly popular demand-generating strategy, which – through its multichannelled dissemination of the generated message – gives it a much greater reach. Lead generation assists organisations in achieving a greater brand awareness, building relationships and attracting more potential clients to fill their sales pipeline. The primary purpose of this publication is identifying the possibilities that the implementation of lead generation strategies provides to modern enterprises. It discusses the key aspects of this issue, demonstrating how the significance of organisations change, how their value effectively increases as a result of the implementation of tools furnished by processes that form an integral part of lead generation. The article defines the factors and processes that affect the effective course of actions undertaken within lead generation campaigns.

  15. Determining the bioavailability and toxicity of lead contamination to earthworms requires using a combination of physicochemical and biological methods

    International Nuclear Information System (INIS)

    Luo, Wei; Verweij, Rudo A.; Gestel, Cornelis A.M. van

    2014-01-01

    This study aimed at assessing the bioavailability and toxicity of lead to Eisenia andrei in shooting range soils representing different land uses (forest, grassland, bullet plot). Soils contained 47–2398 mg Pb/kg dry weight (dw), but also had different pH-CaCl 2 (3.2–6.8) and organic matter contents (3.8–13%). Therefore artificial soils with different pH and organic matter contents and two natural soils were included as control soils. Earthworms were exposed for 28 days and toxicity and uptake of Pb were related to total, water and 0.01 M CaCl 2 extractable and porewater Pb concentrations as well as to soil characteristics. Pb uptake in the earthworms linearly increased with increasing soil concentrations. At >2000 mg Pb/kg dw and pH 3.3–3.5, high earthworm mortality with significant weight loss and complete inhibition of reproduction were recorded. At <1000 mg/kg dw, earthworm reproduction was more related to differences in pH and other soil characteristics than to Pb. -- Highlights: • Availability and earthworm toxicity of Pb determined in field-contaminated soils. • Earthworm toxicity of most-polluted soils explained from available Pb levels. • Earthworm response in less polluted soils mainly determined by soil pH. • Earthworm toxicity correlated with Pb uptake from the soil. • Soil properties explained differences in earthworm Pb uptake and effects. -- Combination of physicochemical and biological assays helped explaining Pb toxicity in shooting range soils from available Pb concentrations and soil characteristics

  16. Confronting actual influence of radiation on human bodies and biological defense mechanism

    International Nuclear Information System (INIS)

    Matsubara, Junko

    2012-01-01

    After the accident at Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, social, economical, psychological pressures on local residents and fears of radiation among the general public have not been resolved. Based on the assumption that the negligence of specialists to clearly explain the influence of radiation on human bodies to the general public is the factor for above mentioned pressures and fears, the influence of radiation from a realistic view was discussed. The topics covered are: (1) understanding the meaning of radiation regulation, (2) radiation and threshold values, (3) actual influence of low-dose radiation, (4) chemical and biological defense in defense mechanism against radiation, (5) problems raised by Fukushima Daiichi nuclear accident. Furthermore, the article explains the principles and the applications of biological defense function activation, and suggested that self-help efforts to fight against stress are from now on. (S.K.)

  17. Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts.

    Science.gov (United States)

    Zhang, Xiaowei; Sahraei, Elham; Wang, Kai

    2016-09-01

    Separator integrity is an important factor in preventing internal short circuit in lithium-ion batteries. Local penetration tests (nail or conical punch) often produce presumably sporadic results, where in exactly similar cell and test set-ups one cell goes to thermal runaway while the other shows minimal reactions. We conducted an experimental study of the separators under mechanical loading, and discovered two distinct deformation and failure mechanisms, which could explain the difference in short circuit characteristics of otherwise similar tests. Additionally, by investigation of failure modes, we provided a hypothesis about the process of formation of local "soft short circuits" in cells with undetectable failure. Finally, we proposed a criterion for predicting onset of soft short from experimental data.

  18. Features of Knowledge Building in Biology: Understanding Undergraduate Students’ Ideas about Molecular Mechanisms

    Science.gov (United States)

    Southard, Katelyn; Wince, Tyler; Meddleton, Shanice; Bolger, Molly S.

    2016-01-01

    Research has suggested that teaching and learning in molecular and cellular biology (MCB) is difficult. We used a new lens to understand undergraduate reasoning about molecular mechanisms: the knowledge-integration approach to conceptual change. Knowledge integration is the dynamic process by which learners acquire new ideas, develop connections between ideas, and reorganize and restructure prior knowledge. Semistructured, clinical think-aloud interviews were conducted with introductory and upper-division MCB students. Interviews included a written conceptual assessment, a concept-mapping activity, and an opportunity to explain the biomechanisms of DNA replication, transcription, and translation. Student reasoning patterns were explored through mixed-method analyses. Results suggested that students must sort mechanistic entities into appropriate mental categories that reflect the nature of MCB mechanisms and that conflation between these categories is common. We also showed how connections between molecular mechanisms and their biological roles are part of building an integrated knowledge network as students develop expertise. We observed differences in the nature of connections between ideas related to different forms of reasoning. Finally, we provide a tentative model for MCB knowledge integration and suggest its implications for undergraduate learning. PMID:26931398

  19. A comparison of molecular biology mechanism of Shewanella putrefaciens between fresh and terrestrial sewage wastewater

    Directory of Open Access Journals (Sweden)

    Jiajie Xu

    2016-11-01

    Full Text Available Municipal and industrial wastewater is often discharged into the environment without appropriate treatment, especially in developing countries. As a result, many rivers and oceans are contaminated. It is urgent to control and administer treatments to these contaminated rivers and oceans. However, most mechanisms of bacterial colonization in contaminated rivers and oceans were unknown, especially in sewage outlets. We found Shewanella putrefaciens to be the primary bacteria in the terrestrial sewage wastewater outlets around Ningbo City, China. Therefore, in this study, we applied a combination of differential proteomics, metabolomics, and real-time fluorescent quantitative PCR techniques to identify bacteria intracellular metabolites. We found S. putrefaciens had 12 different proteins differentially expressed in freshwater culture than when grown in wastewater, referring to the formation of biological membranes (Omp35, OmpW, energy metabolism (SOD, deoxyribose-phosphate pyrophosphokinase, fatty acid metabolism (beta-ketoacyl synthase, secondary metabolism, TCA cycle, lysine degradation (2-oxoglutarate reductase, and propionic acid metabolism (succinyl coenzyme A synthetase. The sequences of these 12 differentially expressed proteins were aligned with sequences downloaded from NCBI. There are also 27 differentially concentrated metabolites detected by NMR, including alcohols (ethanol, isopropanol, amines (dimethylamine, ethanolamine, amino acids (alanine, leucine, amine compounds (bilinerurine, nucleic acid compounds (nucleosides, inosines, organic acids (formate, acetate. Formate and ethanolamine show significant difference between the two environments and are possibly involved in energy metabolism, glycerophospholipid and ether lipids metabolism to provide energy supply and material basis for engraftment in sewage. Because understanding S. putrefaciens’s biological mechanism of colonization (protein, gene express and metabolites in

  20. Modeling of the bacterial mechanism of methicillin-resistance by a systems biology approach.

    Directory of Open Access Journals (Sweden)

    Ida Autiero

    Full Text Available BACKGROUND: A microorganism is a complex biological system able to preserve its functional features against external perturbations and the ability of the living systems to oppose to these external perturbations is defined "robustness". The antibiotic resistance, developed by different bacteria strains, is a clear example of robustness and of ability of the bacterial system to acquire a particular functional behaviour in response to environmental changes. In this work we have modeled the whole mechanism essential to the methicillin-resistance through a systems biology approach. The methicillin is a beta-lactamic antibiotic that act by inhibiting the penicillin-binding proteins (PBPs. These PBPs are involved in the synthesis of peptidoglycans, essential mesh-like polymers that surround cellular enzymes and are crucial for the bacterium survival. METHODOLOGY: The network of genes, mRNA, proteins and metabolites was created using CellDesigner program and the data of molecular interactions are stored in Systems Biology Markup Language (SBML. To simulate the dynamic behaviour of this biochemical network, the kinetic equations were associated with each reaction. CONCLUSIONS: Our model simulates the mechanism of the inactivation of the PBP by methicillin, as well as the expression of PBP2a isoform, the regulation of the SCCmec elements (SCC: staphylococcal cassette chromosome and the synthesis of peptidoglycan by PBP2a. The obtained results by our integrated approach show that the model describes correctly the whole phenomenon of the methicillin resistance and is able to respond to the external perturbations in the same way of the real cell. Therefore, this model can be useful to develop new therapeutic approaches for the methicillin control and to understand the general mechanism regarding the cellular resistance to some antibiotics.

  1. Lead extraction from Cathode Ray Tube (CRT) funnel glass: Reaction mechanisms in thermal reduction with addition of carbon (C).

    Science.gov (United States)

    Lu, Xingwen; Ning, Xun-An; Chen, Da; Chuang, Kui-Hao; Shih, Kaimin; Wang, Fei

    2018-06-01

    This study quantitatively determined the extraction of lead from CRT funnel glass and examined the mechanisms of thermally reducing lead in the products of sintering Pb-glass with carbon in the pre-heated furnace. The experimentally derived results indicate that a 90.3 wt% lead extraction efficiency can be achieved with 20 wt% of C addition at 950 °C for 3 min under air. The formation of viscous semi-liquid glass blocked the oxygen supply between the interaction of C and Pb-glass, and was highly effective for the extraction of metallic Pb. A maximum of 87.3% lead recover was obtained with a C to Na 2 CO 3 ratio of 1/3 at 1200 °C. The decrease of C/Na 2 CO 3 ratio enhanced the metallic lead recovery by increasing the glass viscosity for effective sedimentation of metallic lead in the bottom. However, with the further increase of temperature and treatment time, re-vitrification of lead back to silicate-glass matrix was detected in both Pb-glass/C and Pb-glass/C/Na 2 CO 3 systems. The findings indicated that with proper controls, using C as an inexpensive reagent can effectively reduce treatment time and energy, which is crucial to a waste-to-resource technology for economically recovering lead from the waste CRT glass. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Research and development regarding the retaining mechanism of lead ions in industrial wastewaters using natural matter with remarkable properties

    Science.gov (United States)

    Pop, A.; Iepure, G.

    2017-05-01

    The paper shows the studying of the retaining mechanism of lead ions in industrial wastewaters through static and dynamic ion exchange mechanisms. In the experimental determinations of the lead metallic ion retention, metallurgical industry wastewaters have been used on samples of volcanic zeolite tuff (from Barsana, Maramures), samples that show a high concentration of lead ions and an acidic pH. The results showed that both the static and the dynamic ion exchanges ended with good results and they were consistent with other studies conducted on clinoptilolite zeolite tuff. Knowing that the industrial sector is an important source of environment pollution and degradation and being aware of what a serious threat the heavy metal pollution is, due to their high toxicity and stability, the experiment may find applicability in different aspects, both in the Maramures mining basing as well as in the worldwide controlling and directing of the polluting processes.

  3. The Biology of Atherosclerosis: General Paradigms and Distinct Pathogenic Mechanisms Among HIV-Infected Patients

    OpenAIRE

    Lo, Janet; Plutzky, Jorge

    2012-01-01

    Complications of atherosclerosis, including myocardial infarction and stroke, are the leading cause of death and disability worldwide. Recent data strongly implicate cardiovascular death as a contributor to mortality among patients with human immunodeficiency virus (HIV) infection, with evidence suggesting increased incidence of atherosclerosis among these patients. Therefore, greater understanding of atherosclerotic mechanisms and how these responses may be similar or distinct in HIV-infecte...

  4. Floral biology and reproductive mechanisms of the Ocimum canum Sims (Lamiaceae

    Directory of Open Access Journals (Sweden)

    Cláudio Lúcio Fernandes Amaral

    2008-06-01

    Full Text Available The Ocimum genus (Lamiaceae presents essential oils used in the pharmaceutical, perfume, cosmetics and culinary industries. The aim of this paper was to study the fl oral biology and breeding mechanisms of Ocimum canum Sims. in relation to improved plant breeding. Ocimum canum has inflorescences with white, protandrous and hermaphoditic flowers. The osmophores are located at the anthers and stigma. Anthesis occurs between 10:30 and 11:30 a.m. The main fl oral visitors were bees of the Apis and Augochloropsis genuses. Ocimum canum presents a breeding system with a predominance of outcrossing that possibly demonstrates the wide reproductive flexibility of this species.

  5. Does the Fit Between Competitive Strategy and Administrative Mechanisms Lead to Superior Performance?

    OpenAIRE

    Barth, Henrik

    2000-01-01

    At least two different administrative mechanisms are available for the small business manager to develop and pursue a competitive strategy. One refers to managerial skills needed to implement and follow the competitive strategy chosen by the firm. The other refers to the design of organisation structure i.e. how job tasks are divided, grouped and coordinated. This paper argues that the fit between the competitive strategy followed by a firm and the utilisation of the administrative mechanisms...

  6. Epigenetic Mechanisms in Bone Biology and Osteoporosis: Can They Drive Therapeutic Choices?

    Science.gov (United States)

    Marini, Francesca; Cianferotti, Luisella; Brandi, Maria Luisa

    2016-08-12

    Osteoporosis is a complex multifactorial disorder of the skeleton. Genetic factors are important in determining peak bone mass and structure, as well as the predisposition to bone deterioration and fragility fractures. Nonetheless, genetic factors alone are not sufficient to explain osteoporosis development and fragility fracture occurrence. Indeed, epigenetic factors, representing a link between individual genetic aspects and environmental influences, are also strongly suspected to be involved in bone biology and osteoporosis. Recently, alterations in epigenetic mechanisms and their activity have been associated with aging. Also, bone metabolism has been demonstrated to be under the control of epigenetic mechanisms. Runt-related transcription factor 2 (RUNX2), the master transcription factor of osteoblast differentiation, has been shown to be regulated by histone deacetylases and microRNAs (miRNAs). Some miRNAs were also proven to have key roles in the regulation of Wnt signalling in osteoblastogenesis, and to be important for the positive or negative regulation of both osteoblast and osteoclast differentiation. Exogenous and environmental stimuli, influencing the functionality of epigenetic mechanisms involved in the regulation of bone metabolism, may contribute to the development of osteoporosis and other bone disorders, in synergy with genetic determinants. The progressive understanding of roles of epigenetic mechanisms in normal bone metabolism and in multifactorial bone disorders will be very helpful for a better comprehension of disease pathogenesis and translation of this information into clinical practice. A deep understanding of these mechanisms could help in the future tailoring of proper individual treatments, according to precision medicine's principles.

  7. Biologically Safe Poly(l-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties.

    Science.gov (United States)

    Oyama, Hideko T; Tanishima, Daisuke; Ogawa, Ryohei

    2017-04-10

    Although poly(l-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.

  8. Optimal Ordering Policy and Coordination Mechanism of a Supply Chain with Controllable Lead-Time-Dependent Demand Forecast

    Directory of Open Access Journals (Sweden)

    Hua-Ming Song

    2011-01-01

    Full Text Available This paper investigates the ordering decisions and coordination mechanism for a distributed short-life-cycle supply chain. The objective is to maximize the whole supply chain's expected profit and meanwhile make the supply chain participants achieve a Pareto improvement. We treat lead time as a controllable variable, thus the demand forecast is dependent on lead time: the shorter lead time, the better forecast. Moreover, optimal decision-making models for lead time and order quantity are formulated and compared in the decentralized and centralized cases. Besides, a three-parameter contract is proposed to coordinate the supply chain and alleviate the double margin in the decentralized scenario. In addition, based on the analysis of the models, we develop an algorithmic procedure to find the optimal ordering decisions. Finally, a numerical example is also presented to illustrate the results.

  9. Biological defense mechanisms against DNA double-strand break and their possible medical applications

    International Nuclear Information System (INIS)

    Matsumoto, Yoshihisa

    2011-01-01

    Radiation is now widely used for clinical diagnosis and therapeutics. On the other hand, radiation influences various tissues represented by immunological and reproductive systems, and is also recognized as one of the cause of carcinogenesis. Such pleiotropic effects of radiation are mediated through generation of damages on DNA molecule, vitally important genetic macromolecule. Among various types of DNA damages, double-strand break (DSB) is considered most critical and, therefore, responsible for biological effects. DSB is repaired mainly through two pathways: non-homologous end joining (NHEJ) and homologous recombination (HR). Understanding of these mechanisms has been greatly deepened in past 20 years and is now providing a promising approach toward cancer therapy. We have studied the mechanisms of NHEJ, focusing especially on the role of phosphorylation and the assembly of machinery therein, which will be introduced below. (author)

  10. Microstructure, mechanical properties, and biological response to functionally graded HA coatings

    International Nuclear Information System (INIS)

    Rabiei, Afsaneh; Blalock, Travis; Thomas, Brent; Cuomo, Jerry; Yang, Y.; Ong, Joo

    2007-01-01

    Hydroxyapatite (HA) [Ca 10 (PO 4 ) 6 (OH) 2 ] is the primary mineral content, representing 43% by weight, of bone. Applying a thin layer of HA, to the surface of a metal implant, can promote osseointegration and increase the mechanical stability of the implant. In this study, a biocompatible coating comprising an HA film with functionally graded crystallinity is being deposited on a heated substrate in an Ion Beam Assisted Deposition (IBAD) system. The microstructure of the film was studied using Transmission Electron Microscopy techniques. Finally, initial cell adhesion and cell differentiation on the coating was evaluated using ATCC CRL 1486 human embryonic palatal mesenchymal cell, an osteoblast precursor cell line. The results have shown superior mechanical properties and biological response to the functionally graded HA film

  11. A few nascent methods for measuring mechanical properties of the biological cell.

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, Gayle Echo; de Boer, Maarten Pieter; Corvalan, Carlos (Purdue University, West Lafayette, IN); Corwin, Alex David; Campanella, Osvaldo H. (Purdue University, West Lafayette, IN); Nivens, David (Purdue University, West Lafayette, IN); Werely, Steven (Purdue University, West Lafayette, IN); Sumali, Anton Hartono; Koch, Steven John

    2006-01-01

    This report summarizes a survey of several new methods for obtaining mechanical and rheological properties of single biological cells, in particular: (1) The use of laser Doppler vibrometry (LDV) to measure the natural vibrations of certain cells. (2) The development of a novel micro-electro-mechanical system (MEMS) for obtaining high-resolution force-displacement curves. (3) The use of the atomic force microscope (AFM) for cell imaging. (4) The adaptation of a novel squeezing-flow technique to micro-scale measurement. The LDV technique was used to investigate the recent finding reported by others that the membranes of certain biological cells vibrate naturally, and that the vibration can be detected clearly with recent instrumentation. The LDV has been reported to detect motions of certain biological cells indirectly through the motion of a probe. In this project, trials on Saccharomyces cerevisiae tested and rejected the hypothesis that the LDV could measure vibrations of the cell membranes directly. The MEMS investigated in the second technique is a polysilicon surface-micromachined force sensor that is able to measure forces to a few pN in both air and water. The simple device consists of compliant springs with force constants as low as 0.3 milliN/m and Moire patterns for nanometer-scale optical displacement measurement. Fields from an electromagnet created forces on magnetic micro beads glued to the force sensors. These forces were measured and agreed well with finite element prediction. It was demonstrated that the force sensor was fully functional when immersed in aqueous buffer. These results show the force sensors can be useful for calibrating magnetic forces on magnetic beads and also for direct measurement of biophysical forces on-chip. The use of atomic force microscopy (AFM) for profiling the geometry of red blood cells was the third technique investigated here. An important finding was that the method commonly used for attaching the cells to a

  12. Chitosan fibers with improved biological and mechanical properties for tissue engineering applications.

    Science.gov (United States)

    Albanna, Mohammad Z; Bou-Akl, Therese H; Blowytsky, Oksana; Walters, Henry L; Matthew, Howard W T

    2013-04-01

    The low mechanical properties of hydrogel materials such as chitosan hinder their broad utility for tissue engineering applications. Previous research efforts improved the mechanical properties of chitosan fiber through chemical and physical modifications; however, unfavorable toxicity effects on cells were reported. In this paper, we report the preparation of chitosan fibers with improved mechanical and biocompatibility properties. The structure-property relationships of extruded chitosan fibers were explored by varying acetic acid (AA) concentration, ammonia concentration, annealing temperature and degree of heparin crosslinking. Results showed that optimizing AA concentration to 2vol% improved fiber strength and stiffness by 2-fold. Extruding chitosan solution into 25wt% of ammonia solution reduced fiber diameters and improved fiber strength by 2-fold and stiffness by 3-fold, due to an increase in crystallinity as confirmed by XRD. Fiber annealing further reduced fiber diameter and improved fiber strength and stiffness as temperature increased. Chitosan fibers crosslinked with heparin had increased diameter but lower strength and stiffness properties and higher breaking strain values. When individual parameters were combined, further improvement in fiber mechanical properties was achieved. All mechanically improved fibers and heparin crosslinked fibers promoted valvular interstitial cells (VIC) attachment and growth over 10 day cultures. Our results demonstrate the ability to substantially improve the mechanical properties of chitosan fibers without adversely affecting their biological properties. The investigated treatments offer numerous advantages over previous physical/chemical modifications and thus are expected to expand the utility of chitosan fibers with tunable mechanical properties in various tissue engineering applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Investigations on mechanical biological treatment of waste in South America: Towards more sustainable MSW management strategies

    International Nuclear Information System (INIS)

    Bezama, Alberto; Aguayo, Pablo; Konrad, Odorico; Navia, Rodrigo; Lorber, Karl E.

    2007-01-01

    This work presents an analysis on the suitability of mechanical biological treatment of municipal solid waste in South America, based on two previous experimental investigations carried out in two different countries. The first experiment was performed for determining the mass and volume reduction of MSW in the province of Concepcion (Chile). The implemented bench-scale process consisted of a manual classification and separation stage, followed by an in-vessel biological degradation process. The second experiment consisted of a full-scale experiment performed in the city of Estrela (Brazil), where the existing municipal waste management facility was adapted to enhance the materials sorting and separation. Expressed in wet weight composition, 85.5% of the material input in the first experiment was separated for biological degradation. After 27 days of processing, 60% of the initial mass was reduced through degradation and water evaporation. The final fraction destined for landfilling equals 59% of the total input mass, corresponding to about 50% of the initial volume. In the second experiment, the fraction destined to landfill reaches 46.6% of the total input waste mass, whilst also significantly reducing the total volume to be disposed. These results, and the possible recovery of material streams suitable for recycling or for preparing solid recovered fuels, are the main advantages of the studied process

  14. Mechanical fatigue resistance of an implantable branched lead system for a distributed set of longitudinal intrafascicular electrodes.

    Science.gov (United States)

    Pena, A E; Kuntaegowdanahalli, S S; Abbas, J J; Patrick, J; Horch, K W; Jung, R

    2017-12-01

    A neural interface system has been developed that consists of an implantable stimulator/recorder can with a 15-electrode lead that trifurcates into three bundles of five individual wire longitudinal intrafascicular electrodes. This work evaluated the mechanical fatigue resistance of the branched lead and distributed electrode system under conditions designed to mimic anticipated strain profiles that would be observed after implantation in the human upper arm. Custom test setups and procedures were developed to apply linear or angular strain at four critical stress riser points on the lead and electrode system. Each test was performed to evaluate fatigue under a high repetition/low amplitude paradigm designed to test the effects of arm movement on the leads during activities such as walking, or under a low repetition/high amplitude paradigm designed to test the effects of more strenuous upper arm activities. The tests were performed on representative samples of the implantable lead system for human use. The specimens were fabricated using procedures equivalent to those that will be used during production of human-use implants. Electrical and visual inspections of all test specimens were performed before and after the testing procedures to assess lead integrity. Measurements obtained before and after applying repetitive strain indicated that all test specimens retained electrical continuity and that electrical impedance remained well below pre-specified thresholds for detection of breakage. Visual inspection under a microscope at 10×  magnification did not reveal any signs of damage to the wires or silicone sheathing at the stress riser points. These results demonstrate that the branched lead of this implantable neural interface system has sufficient mechanical fatigue resistance to withstand strain profiles anticipated when the system is implanted in an arm. The novel test setups and paradigms may be useful in testing other lead systems.

  15. Mechanical fatigue resistance of an implantable branched lead system for a distributed set of longitudinal intrafascicular electrodes

    Science.gov (United States)

    Pena, A. E.; Kuntaegowdanahalli, S. S.; Abbas, J. J.; Patrick, J.; Horch, K. W.; Jung, R.

    2017-12-01

    Objective. A neural interface system has been developed that consists of an implantable stimulator/recorder can with a 15-electrode lead that trifurcates into three bundles of five individual wire longitudinal intrafascicular electrodes. This work evaluated the mechanical fatigue resistance of the branched lead and distributed electrode system under conditions designed to mimic anticipated strain profiles that would be observed after implantation in the human upper arm. Approach. Custom test setups and procedures were developed to apply linear or angular strain at four critical stress riser points on the lead and electrode system. Each test was performed to evaluate fatigue under a high repetition/low amplitude paradigm designed to test the effects of arm movement on the leads during activities such as walking, or under a low repetition/high amplitude paradigm designed to test the effects of more strenuous upper arm activities. The tests were performed on representative samples of the implantable lead system for human use. The specimens were fabricated using procedures equivalent to those that will be used during production of human-use implants. Electrical and visual inspections of all test specimens were performed before and after the testing procedures to assess lead integrity. Main results. Measurements obtained before and after applying repetitive strain indicated that all test specimens retained electrical continuity and that electrical impedance remained well below pre-specified thresholds for detection of breakage. Visual inspection under a microscope at 10×  magnification did not reveal any signs of damage to the wires or silicone sheathing at the stress riser points. Significance. These results demonstrate that the branched lead of this implantable neural interface system has sufficient mechanical fatigue resistance to withstand strain profiles anticipated when the system is implanted in an arm. The novel test setups and paradigms may be useful in

  16. Introducing memory and association mechanism into a biologically inspired visual model.

    Science.gov (United States)

    Qiao, Hong; Li, Yinlin; Tang, Tang; Wang, Peng

    2014-09-01

    A famous biologically inspired hierarchical model (HMAX model), which was proposed recently and corresponds to V1 to V4 of the ventral pathway in primate visual cortex, has been successfully applied to multiple visual recognition tasks. The model is able to achieve a set of position- and scale-tolerant recognition, which is a central problem in pattern recognition. In this paper, based on some other biological experimental evidence, we introduce the memory and association mechanism into the HMAX model. The main contributions of the work are: 1) mimicking the active memory and association mechanism and adding the top down adjustment to the HMAX model, which is the first try to add the active adjustment to this famous model and 2) from the perspective of information, algorithms based on the new model can reduce the computation storage and have a good recognition performance. The new model is also applied to object recognition processes. The primary experimental results show that our method is efficient with a much lower memory requirement.

  17. Mechanical Properties of a High Lead Glass Used in the Mars Organic Molecule Analyzer

    Science.gov (United States)

    Salem, Jonathan A.; Smith, Nathan A.; Ersahin, Akif

    2015-01-01

    The elastic constants, strength, fracture toughness, slow crack growth parameters, and mirror constant of a high lead glass supplied as tubes and funnels were measured using ASTM International (formerly ASTM, American Society for Testing and Materials) methods and modifications thereof. The material exhibits lower Young's modulus and slow crack growth exponent as compared to soda-lime silica glass. Highly modified glasses exhibit lower fracture toughness and slow crack growth exponent than high purity glasses such as fused silica.

  18. When and how does labour lead to love? The ontogeny and mechanisms of the IKEA effect

    OpenAIRE

    Marsh, Lauren E.; Kanngiesser, Patricia; Hood, Bruce

    2018-01-01

    We elevate our constructions to a special status in our minds. This ‘IKEA’ effect leads us to believe that our creations are more valuable than items that are identical, but constructed by another. This series of studies utilises a developmental perspective to explore why this bias exists. Study 1 elucidates the ontogeny of the IKEA effect, demonstrating an emerging bias at age 5, corresponding with key developmental milestones in self-concept formation. Study 2 assesses the role of effort, r...

  19. Mechanisms of action of sacubitril/valsartan on cardiac remodeling: a systems biology approach.

    Science.gov (United States)

    Iborra-Egea, Oriol; Gálvez-Montón, Carolina; Roura, Santiago; Perea-Gil, Isaac; Prat-Vidal, Cristina; Soler-Botija, Carolina; Bayes-Genis, Antoni

    2017-01-01

    Sacubitril/Valsartan, proved superiority over other conventional heart failure management treatments, but its mechanisms of action remains obscure. In this study, we sought to explore the mechanistic details for Sacubitril/Valsartan in heart failure and post-myocardial infarction remodeling, using an in silico, systems biology approach. Myocardial transcriptome obtained in response to myocardial infarction in swine was analyzed to address post-infarction ventricular remodeling. Swine transcriptome hits were mapped to their human equivalents using Reciprocal Best (blast) Hits, Gene Name Correspondence, and InParanoid database. Heart failure remodeling was studied using public data available in gene expression omnibus (accession GSE57345, subseries GSE57338), processed using the GEO2R tool. Using the Therapeutic Performance Mapping System technology, dedicated mathematical models trained to fit a set of molecular criteria, defining both pathologies and including all the information available on Sacubitril/Valsartan, were generated. All relationships incorporated into the biological network were drawn from public resources (including KEGG, REACTOME, INTACT, BIOGRID, and MINT). An artificial neural network analysis revealed that Sacubitril/Valsartan acts synergistically against cardiomyocyte cell death and left ventricular extracellular matrix remodeling via eight principal synergistic nodes. When studying each pathway independently, Valsartan was found to improve cardiac remodeling by inhibiting members of the guanine nucleotide-binding protein family, while Sacubitril attenuated cardiomyocyte cell death, hypertrophy, and impaired myocyte contractility by inhibiting PTEN. The complex molecular mechanisms of action of Sacubitril/Valsartan upon post-myocardial infarction and heart failure cardiac remodeling were delineated using a systems biology approach. Further, this dataset provides pathophysiological rationale for the use of Sacubitril/Valsartan to prevent post

  20. Effect of calcium hydroxide on mechanical strength and biological properties of bioactive glass.

    Science.gov (United States)

    Shah, Asma Tufail; Batool, Madeeha; Chaudhry, Aqif Anwar; Iqbal, Farasat; Javaid, Ayesha; Zahid, Saba; Ilyas, Kanwal; Bin Qasim, Saad; Khan, Ather Farooq; Khan, Abdul Samad; Ur Rehman, Ihtesham

    2016-08-01

    In this manuscript for the first time calcium hydroxide (Ca(OH)2) has been used for preparation of bioactive glass (BG-2) by co-precipitation method and compared with glass prepared using calcium nitrate tetrahydrate Ca(NO3)2·4H2O (BG-1), which is a conventional source of calcium. The new source positively affected physical, biological and mechanical properties of BG-2. The glasses were characterized by Fourier transform infrared (FTIR), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA-DSC), BET surface area analysis and Knoop hardness. The results showed that BG-2 possessed relatively larger surface properties (100m(2)g(-1) surface area) as compared to BG-1 (78m(2)g(-1)), spherical morphology and crystalline phases (wollastonite and apatite) after sintering at lower than conventional temperature. These properties contribute critical role in both mechanical and biological properties of glasses. The Knoop hardness measurements revealed that BG-2 possessed much better hardness (0.43±0.06GPa at 680°C and 2.16±0.46GPa at 980°C) than BG-1 (0.24±0.01 at 680°C and 0.57±0.07GPA at 980°C) under same conditions. Alamar blue Assay and confocal microscopy revealed that BG-2 exhibited better attachment and proliferation of MG63 cells. Based on the improved biological properties of BG-2 as a consequent of novel calcium source selection, BG-2 is proposed as a bioactive ceramic for hard tissue repair and regeneration applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Molecular mechanisms of temperature-dependent sex determination in the context of ecological developmental biology.

    Science.gov (United States)

    Matsumoto, Yuiko; Crews, David

    2012-05-06

    Temperature-dependent sex determination (TSD) is a prime example of phenotypic plasticity in that gonadal sex is determined by the temperature of the incubating egg. In the red-eared slider turtle (Trachemys scripta), the effect of temperature can be overridden by exogenous ligands, i.e., sex steroid hormones and steroid metabolism enzyme inhibitors, during the temperature-sensitive period (TSP) of development. Precisely how the physical signal of temperature is transduced into a biological signal that ultimately results in sex determination remains unknown. In this review, we discuss the sex determining pathway underlying TSD by focusing on two candidate sex determining genes, Forkhead box protein L2 (FoxL2) and Doublesex mab3- related transcription factor 1 (Dmrt1). They appear to be involved in transducing the environmental temperature signal into a biological signal that subsequently determines gonadal sex. FoxL2 and Dmrt1 exhibit gonad-typical patterns of expression in response to temperature during the TSP in the red-eared slider turtle. Further, the biologically active ligands regulate the expression of FoxL2 and Dmrt1 during development to modify gonad trajectory. The precise regulatory mechanisms of expression of these genes by temperature or exogenous ligands are not clear. However, the environment often influences developmental gene expression by altering the epigenetic status in regulatory regions. Here, we will discuss if the regulation of FoxL2 and Dmrt1 expression by environment is mediated through epigenetic mechanisms during development in species with TSD. Published by Elsevier Ireland Ltd.

  2. Removing lead from metallic mixture of waste printed circuit boards by vacuum distillation: factorial design and removal mechanism.

    Science.gov (United States)

    Li, Xingang; Gao, Yujie; Ding, Hui

    2013-10-01

    The lead removal from the metallic mixture of waste printed circuit boards by vacuum distillation was optimized using experimental design, and a mathematical model was established to elucidate the removal mechanism. The variables studied in lead evaporation consisted of the chamber pressure, heating temperature, heating time, particle size and initial mass. The low-level chamber pressure was fixed at 0.1 Pa as the operation pressure. The application of two-level factorial design generated a first-order polynomial that agreed well with the data for evaporation efficiency of lead. The heating temperature and heating time exhibited significant effects on the efficiency, which was validated by means of the copper-lead mixture experiments. The optimized operating conditions within the region studied were the chamber pressure of 0.1 Pa, heating temperature of 1023 K and heating time of 120 min. After the conditions were employed to remove lead from the metallic mixture of waste printed circuit boards, the efficiency was 99.97%. The mechanism of the effects was elucidated by mathematical modeling that deals with evaporation, mass transfer and condensation, and can be applied to a wider range of metal removal by vacuum distillation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Meeting the specifications for mechanical-biological waste treament and dumping; Umsetzung der Ablagerungsanforderungen im MBA- und Deponiebetrieb

    Energy Technology Data Exchange (ETDEWEB)

    Ketelsen, K. [IBA Ingenieurbuero fuer Abfallwirtschaft und Entsorgung GmbH, Hannover (Germany)

    2001-07-01

    The new German ordinances will have a dramatic influence on the waste treatment processes and air/exhaust management in mechanical-biological waste treatment plants. The potentials of process control and optimization should be fully utilized. The extensive in-service inspections and specifications will change the requirements on the process and staff qualification. The additional cost must be balanced by technically and economically feasible projecting and solutions. The need to keep up with thermal processes will lead to the construction of plants with a size of 50,000 Mg/a and more as these have higher economic efficiency, i.e. small regional utilities will have to co-operate. In mechanical-biological waste treatment plants, about 40-50% of the total cost is accounted for by the waste treatment process, i.e. economic efficiency will depend on the cost of dumping of the stabilized fine-grained fraction(about 20%) and the cost of utilization of the high-calorific waste (about 30%). In view of the high fixed cost, mechanical-biological waste treatment concepts will be economically efficient only if the plant capacity is fully utilized. [German] Mit Verabschiedung der Verordnungen ist die MBA 'gesellschaftsfaehiger' geworden. Die Verordnungen werden einen nachhaltigen Einfluss auf die Verfahrenstechnik und das gesamte Luft-/Abgasmanagement haben. Die Entwicklungspotentiale in der Prozesssteuerung und -optimierung muessen verstaerkt ausgeschoepft werden. Durch die geforderten umfangreichen Untersuchungs- und Nachweispflichten werden sich die Anforderungen an die Betriebsfuehrung und Personalqualifikation veraendern. Die aus den hoeheren Anforderungen resultierenden Mehrkosten muessen durch technisch und wirtschftlich sinnvolle Planungen und Loesungen in vertretbaren Grenzen gehalten werden. Die Notwendigkeit zur Wirtschaftlichkeit im Wettbewerb mit rein thermischen Verfahren wird auch bei den MBA zur Realisierung wirtschaftlicher Anlagengroessen von groesser

  4. Toward modular biological models: defining analog modules based on referent physiological mechanisms.

    Science.gov (United States)

    Petersen, Brenden K; Ropella, Glen E P; Hunt, C Anthony

    2014-08-16

    Currently, most biomedical models exist in isolation. It is often difficult to reuse or integrate models or their components, in part because they are not modular. Modular components allow the modeler to think more deeply about the role of the model and to more completely address a modeling project's requirements. In particular, modularity facilitates component reuse and model integration for models with different use cases, including the ability to exchange modules during or between simulations. The heterogeneous nature of biology and vast range of wet-lab experimental platforms call for modular models designed to satisfy a variety of use cases. We argue that software analogs of biological mechanisms are reasonable candidates for modularization. Biomimetic software mechanisms comprised of physiomimetic mechanism modules offer benefits that are unique or especially important to multi-scale, biomedical modeling and simulation. We present a general, scientific method of modularizing mechanisms into reusable software components that we call physiomimetic mechanism modules (PMMs). PMMs utilize parametric containers that partition and expose state information into physiologically meaningful groupings. To demonstrate, we modularize four pharmacodynamic response mechanisms adapted from an in silico liver (ISL). We verified the modularization process by showing that drug clearance results from in silico experiments are identical before and after modularization. The modularized ISL achieves validation targets drawn from propranolol outflow profile data. In addition, an in silico hepatocyte culture (ISHC) is created. The ISHC uses the same PMMs and required no refactoring. The ISHC achieves validation targets drawn from propranolol intrinsic clearance data exhibiting considerable between-lab variability. The data used as validation targets for PMMs originate from both in vitro to in vivo experiments exhibiting large fold differences in time scale. This report demonstrates

  5. Effects of voids on thermal-mechanical reliability of lead-free solder joints

    Directory of Open Access Journals (Sweden)

    Benabou Lahouari

    2014-06-01

    Full Text Available Reliability of electronic packages has become a major issue, particularly in systems used in electrical or hybrid cars where severe operating conditions must be met. Many studies have shown that solder interconnects are critical elements since many failure mechanisms originate from their typical response under thermal cycles. In this study, effects of voids in solder interconnects on the electronic assembly lifetime are estimated based on finite element simulations.

  6. Glutamate transporter type 3 knockout leads to decreased heart rate possibly via parasympathetic mechanism

    OpenAIRE

    Deng, Jiao; Li, Jiejie; Li, Liaoliao; Feng, Chenzhuo; Xiong, Lize; Zuo, Zhiyi

    2013-01-01

    Parasympathetic tone is a dominant neural regulator for basal heart rate. Glutamate transporters (EAAT) via their glutamate uptake functions regulate glutamate neurotransmission in the central nervous system. We showed that EAAT type 3 (EAAT3) knockout mice had a slower heart rate than wild-type mice when they were anesthetized. We design this study to determine whether non-anesthetized EAAT3 knockout mice have a slower heart rate and, if so, what may be the mechanism for this effect. Young a...

  7. AFM and SEM-FEG study on fundamental mechanisms leading to fatigue crack initiation

    Czech Academy of Sciences Publication Activity Database

    Man, Jiří; Valtr, M.; Petrenec, Martin; Dluhoš, J.; Kuběna, Ivo; Obrtlík, Karel; Polák, Jaroslav

    2015-01-01

    Roč. 76, JUL (2015), s. 11-18 ISSN 0142-1123 R&D Projects: GA ČR(CZ) GAP108/10/2371; GA MŠk(CZ) ED1.1.00/02.0068; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : fatigue crack initiation * 316L austenitic steel * atomic force microscopy * extrusion * intrusion Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.162, year: 2015

  8. Quantum-Mechanics Methodologies in Drug Discovery: Applications of Docking and Scoring in Lead Optimization.

    Science.gov (United States)

    Crespo, Alejandro; Rodriguez-Granillo, Agustina; Lim, Victoria T

    2017-01-01

    The development and application of quantum mechanics (QM) methodologies in computer- aided drug design have flourished in the last 10 years. Despite the natural advantage of QM methods to predict binding affinities with a higher level of theory than those methods based on molecular mechanics (MM), there are only a few examples where diverse sets of protein-ligand targets have been evaluated simultaneously. In this work, we review recent advances in QM docking and scoring for those cases in which a systematic analysis has been performed. In addition, we introduce and validate a simplified QM/MM expression to compute protein-ligand binding energies. Overall, QMbased scoring functions are generally better to predict ligand affinities than those based on classical mechanics. However, the agreement between experimental activities and calculated binding energies is highly dependent on the specific chemical series considered. The advantage of more accurate QM methods is evident in cases where charge transfer and polarization effects are important, for example when metals are involved in the binding process or when dispersion forces play a significant role as in the case of hydrophobic or stacking interactions. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. When and how does labour lead to love? The ontogeny and mechanisms of the IKEA effect.

    Science.gov (United States)

    Marsh, Lauren E; Kanngiesser, Patricia; Hood, Bruce

    2018-01-01

    We elevate our constructions to a special status in our minds. This 'IKEA' effect leads us to believe that our creations are more valuable than items that are identical, but constructed by another. This series of studies utilises a developmental perspective to explore why this bias exists. Study 1 elucidates the ontogeny of the IKEA effect, demonstrating an emerging bias at age 5, corresponding with key developmental milestones in self-concept formation. Study 2 assesses the role of effort, revealing that the IKEA effect is not moderated by the amount of effort invested in the task in 5-to-6-year olds. Finally, Study 3 examines whether feelings of ownership moderate the IKEA effect, finding that ownership alone cannot explain why children value their creations more. Altogether, results from this study series are incompatible with existing theories of the IKEA bias. Instead, we propose a new framework to examine biases in decision making. Perhaps the IKEA effect reflects a link between our creations and our self-concept, emerging at age 5, leading us to value them more positively than others' creations. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Replisome-mediated Translesion Synthesis and Leading Strand Template Lesion Skipping Are Competing Bypass Mechanisms*

    Science.gov (United States)

    Gabbai, Carolina B.; Yeeles, Joseph T. P.; Marians, Kenneth J.

    2014-01-01

    A number of different enzymatic pathways have evolved to ensure that DNA replication can proceed past template base damage. These pathways include lesion skipping by the replisome, replication fork regression followed by either correction of the damage and origin-independent replication restart or homologous recombination-mediated restart of replication downstream of the lesion, and bypass of the damage by a translesion synthesis DNA polymerase. We report here that of two translesion synthesis polymerases tested, only DNA polymerase IV, not DNA polymerase II, could engage productively with the Escherichia coli replisome to bypass leading strand template damage, despite the fact that both enzymes are shown to be interacting with the replicase. Inactivation of the 3′ → 5′ proofreading exonuclease of DNA polymerase II did not enable bypass. Bypass by DNA polymerase IV required its ability to interact with the β clamp and act as a translesion polymerase but did not require its “little finger” domain, a secondary region of interaction with the β clamp. Bypass by DNA polymerase IV came at the expense of the inherent leading strand lesion skipping activity of the replisome, indicating that they are competing reactions. PMID:25301949

  11. Mechanical properties of a 316L/T91 weld joint tested in lead-bismuth liquid

    International Nuclear Information System (INIS)

    Serre, Ingrid; Vogt, Jean-Bernard

    2009-01-01

    The mechanical strength of T91/316L weld joint assembled by electron beam process is investigated in air and in a liquid lead bismuth bath at 300 and 380 o C using the small punch test. It is shown that the mechanical response in air of the weld joint is similar to that of the T91 base material. The plastic deformation is mainly concentrated in the T91 part of the weld joint which promotes cracking in this material. Testing in liquid lead bismuth bath results in a reduction in ductility and the formation of brittle cracks. The T91/weld interface is found to be rather resistant as it cracks late in the test and after a large crack propagated in the T91 steel.

  12. Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces.

    Science.gov (United States)

    Cha, Jihoon; Cui, Mingcan; Jang, Min; Cho, Sang-Hyun; Moon, Deok Hyun; Khim, Jeehyeong

    2011-01-01

    This study examines the adsorption isotherms, kinetics and mechanisms of Pb²(+) sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb²(+) in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb²(+) with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca²(+) and PO₄³⁻ concentrations during the metal sorption processes. The Pb²(+) sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb(+). The sorption isotherm results indicated that Pb²(+) sorption onto the Langmuir and Freundlich constant q(max) and K( F ) is 9.52 and 8.18 mg g⁻¹, respectively. Sorption kinetics results indicated that Pb²(+) sorption onto WCBP was pseudo-second-order rate constants K₂ was 1.12 g mg⁻¹ h⁻¹. The main mechanism is adsorption or surface complexation (≡POPb(+): 61.6%), co-precipitation or ion exchange [Ca₃(.)₉₃ Pb₁(.)₀₇ (PO₄)₃ (OH): 21.4%] and other precipitation [Pb 50 mg L⁻¹ and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb²(+) removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb²(+) indicates its potential as another promising way to remediate Pb²(+)-contaminated media.

  13. Hybrid printing of mechanically and biologically improved constructs for cartilage tissue engineering applications

    International Nuclear Information System (INIS)

    Xu Tao; Binder, Kyle W; Albanna, Mohammad Z; Dice, Dennis; Zhao Weixin; Yoo, James J; Atala, Anthony

    2013-01-01

    Bioprinting is an emerging technique used to fabricate viable, 3D tissue constructs through the precise deposition of cells and hydrogels in a layer-by-layer fashion. Despite the ability to mimic the native properties of tissue, printed 3D constructs that are composed of naturally-derived biomaterials still lack structural integrity and adequate mechanical properties for use in vivo, thus limiting their development for use in load-bearing tissue engineering applications, such as cartilage. Fabrication of viable constructs using a novel multi-head deposition system provides the ability to combine synthetic polymers, which have higher mechanical strength than natural materials, with the favorable environment for cell growth provided by traditional naturally-derived hydrogels. However, the complexity and high cost associated with constructing the required robotic system hamper the widespread application of this approach. Moreover, the scaffolds fabricated by these robotic systems often lack flexibility, which further restrict their applications. To address these limitations, advanced fabrication techniques are necessary to generate complex constructs with controlled architectures and adequate mechanical properties. In this study, we describe the construction of a hybrid inkjet printing/electrospinning system that can be used to fabricate viable tissues for cartilage tissue engineering applications. Electrospinning of polycaprolactone fibers was alternated with inkjet printing of rabbit elastic chondrocytes suspended in a fibrin–collagen hydrogel in order to fabricate a five-layer tissue construct of 1 mm thickness. The chondrocytes survived within the printed hybrid construct with more than 80% viability one week after printing. In addition, the cells proliferated and maintained their basic biological properties within the printed layered constructs. Furthermore, the fabricated constructs formed cartilage-like tissues both in vitro and in vivo as evidenced by the

  14. Epigenetic Mechanisms in Bone Biology and Osteoporosis: Can They Drive Therapeutic Choices?

    Directory of Open Access Journals (Sweden)

    Francesca Marini

    2016-08-01

    Full Text Available Osteoporosis is a complex multifactorial disorder of the skeleton. Genetic factors are important in determining peak bone mass and structure, as well as the predisposition to bone deterioration and fragility fractures. Nonetheless, genetic factors alone are not sufficient to explain osteoporosis development and fragility fracture occurrence. Indeed, epigenetic factors, representing a link between individual genetic aspects and environmental influences, are also strongly suspected to be involved in bone biology and osteoporosis. Recently, alterations in epigenetic mechanisms and their activity have been associated with aging. Also, bone metabolism has been demonstrated to be under the control of epigenetic mechanisms. Runt-related transcription factor 2 (RUNX2, the master transcription factor of osteoblast differentiation, has been shown to be regulated by histone deacetylases and microRNAs (miRNAs. Some miRNAs were also proven to have key roles in the regulation of Wnt signalling in osteoblastogenesis, and to be important for the positive or negative regulation of both osteoblast and osteoclast differentiation. Exogenous and environmental stimuli, influencing the functionality of epigenetic mechanisms involved in the regulation of bone metabolism, may contribute to the development of osteoporosis and other bone disorders, in synergy with genetic determinants. The progressive understanding of roles of epigenetic mechanisms in normal bone metabolism and in multifactorial bone disorders will be very helpful for a better comprehension of disease pathogenesis and translation of this information into clinical practice. A deep understanding of these mechanisms could help in the future tailoring of proper individual treatments, according to precision medicine’s principles.

  15. MOLECULAR MECHANISMS THAT LEAD TO CHOLANGIOCARCINOMA, DURING CHRONIC INFECTION OF LIVER FLUKES

    Directory of Open Access Journals (Sweden)

    A. O. Bogdanov

    2015-01-01

    Full Text Available Cholangiocarcinoma is a malignant tumor, characterized by poor prognosis and a low five-year survival rate. There is a clear correlation between the incidence of opisthorchiasis and high incidence of cholangiocarcinoma in South-East Asia. Liver flukes Clonorchis sinensis and Opisthorchis viverrini are I class carcinogens. There are some endemic regions of opisthorchiasis In the Russian Federation. The most important factor that leads to carcinogenesis during liver fluke infection is chronic inflammation. This review article focuses on the communication of chronic inflammation caused by invasion of liver flukes and cholangiocarcinoma. This paper summarizes the current knowledge about the risk factors for cholangiocarcinoma, as well as knowledge about the molecular aspects of the induction of carcinogenesis by liver flukes.

  16. Transport Mechanisms Governing initial Leading-Edge Vortex Development on a Pitching Wing

    Science.gov (United States)

    Wabick, Kevin; Berdon, Randall; Buchholz, James; Johnson, Kyle; Thurow, Brian

    2017-11-01

    The formation and evolution of Leading Edge Vortices (LEVs) are ubiquitous in natural fliers and maneuvering wings, and have a profound impact on aerodynamic loads. The formation of an LEV is experimentally investigated on a pitching flat-plate wing of aspect-ratio 2, and dimensionless pitch rates of k = Ωc / 2 U of 0.1, 0.2, and 0.5, at a Reynolds number of 104. The sources and sinks of vorticity that contribute to the growth and evolution of the LEV are investigated at spanwise regions of interest, and their relative balance is compared to other wing kinematics, and the case of a two-dimensional pitching wing. This work is supported by the Air Force Office of Scientific Research (Grant Number FA9550-16-1-0107, Dr. Douglas Smith, program manager).

  17. Quantum Biology

    Directory of Open Access Journals (Sweden)

    Alessandro Sergi

    2009-06-01

    Full Text Available A critical assessment of the recent developmentsof molecular biology is presented.The thesis that they do not lead to a conceptualunderstanding of life and biological systems is defended.Maturana and Varela's concept of autopoiesis is briefly sketchedand its logical circularity avoided by postulatingthe existence of underlying living processes,entailing amplification from the microscopic to the macroscopic scale,with increasing complexity in the passage from one scale to the other.Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces,is criticized. It is suggested that the correct interpretationof quantum dispersion forces (van der Waals, hydrogen bonding, and so onas quantum coherence effects hints at the necessity of includinglong-ranged forces (or mechanisms for them incondensed matter theories of biological processes.Some quantum effects in biology are reviewedand quantum mechanics is acknowledged as conceptually important to biology since withoutit most (if not all of the biological structuresand signalling processes would not even exist. Moreover, it is suggested that long-rangequantum coherent dynamics, including electron polarization,may be invoked to explain signal amplificationprocess in biological systems in general.

  18. INFLUENCE OF MECHANICAL ALLOYING AND LEAD CONTENT ON MICROSTRUCTURE, HARDNESS AND TRIBOLOGICAL BEHAVIOR OF 6061 ALUMINIUM ALLOYS

    Directory of Open Access Journals (Sweden)

    M. Paidpilli

    2017-03-01

    Full Text Available In the present work, one batch of prealloyed 6061Al powder was processed by mixing and another one was ball milled with varying amount of lead content (0-15 vol. %. These powders were compacted at 300MPa and sintered at 590˚C under N2. The instrumented hardness and the young’s modulus of as-sintered 6061Al-Pb alloys were examined as a function of lead content and processing route. The wear test under dry sliding condition has been performed at varying loads (10-40 N using pin-on-disc tribometer. The microstructure and worn surfaces have been investigated using SEM to evaluate the change in topographical features due to mechanical alloying and lead content. The mechanically alloyed materials showed improved wear characteristics as compared to as-mixed counterpart alloys. Delamination of 6061Al-Pb alloys decreases up to an optimum lead composition in both as-mixed and ball-milled 6061Al-Pb alloys. The results indicated minimum wear rate for as-mixed and ball-milled 6061Al alloy at 5 and 10 vol. % Pb, respectively.

  19. Engineering the mechanical and biological properties of nanofibrous vascular grafts for in situ vascular tissue engineering.

    Science.gov (United States)

    Henry, Jeffrey J D; Yu, Jian; Wang, Aijun; Lee, Randall; Fang, Jun; Li, Song

    2017-08-17

    Synthetic small diameter vascular grafts have a high failure rate, and endothelialization is critical for preventing thrombosis and graft occlusion. A promising approach is in situ tissue engineering, whereby an acellular scaffold is implanted and provides stimulatory cues to guide the in situ remodeling into a functional blood vessel. An ideal scaffold should have sufficient binding sites for biomolecule immobilization and a mechanical property similar to native tissue. Here we developed a novel method to blend low molecular weight (LMW) elastic polymer during electrospinning process to increase conjugation sites and to improve the mechanical property of vascular grafts. LMW elastic polymer improved the elasticity of the scaffolds, and significantly increased the amount of heparin conjugated to the micro/nanofibrous scaffolds, which in turn increased the loading capacity of vascular endothelial growth factor (VEGF) and prolonged the release of VEGF. Vascular grafts were implanted into the carotid artery of rats to evaluate the in vivo performance. VEGF treatment significantly enhanced endothelium formation and the overall patency of vascular grafts. Heparin coating also increased cell infiltration into the electrospun grafts, thus increasing the production of collagen and elastin within the graft wall. This work demonstrates that LMW elastic polymer blending is an approach to engineer the mechanical and biological property of micro/nanofibrous vascular grafts for in situ vascular tissue engineering.

  20. The biology of atherosclerosis: general paradigms and distinct pathogenic mechanisms among HIV-infected patients.

    Science.gov (United States)

    Lo, Janet; Plutzky, Jorge

    2012-06-01

    Complications of atherosclerosis, including myocardial infarction and stroke, are the leading cause of death and disability worldwide. Recent data strongly implicate cardiovascular death as a contributor to mortality among patients with human immunodeficiency virus (HIV) infection, with evidence suggesting increased incidence of atherosclerosis among these patients. Therefore, greater understanding of atherosclerotic mechanisms and how these responses may be similar or distinct in HIV-infected patients is needed. Key concepts in atherosclerosis are reviewed, including the evidence that inflammation and abnormal metabolism are major drivers of atherosclerosis, and connected to the current literature regarding atherosclerosis in the context of HIV.

  1. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    International Nuclear Information System (INIS)

    Haseroth, Helmut; Hora, Heinrich; Regensburg Inst. of Tech.

    1996-01-01

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10 11 C 4+ ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ''hot'' electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author)

  2. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Haseroth, Helmut [European Organization for Nuclear Research, Geneva (Switzerland); Hora, Heinrich [New South Wales Univ., Kensington, NSW (Australia)]|[Regensburg Inst. of Tech. (Germany). Anwenderzentrum

    1996-12-31

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10{sup 11} C{sup 4+} ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ``hot`` electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author).

  3. Hypoxic ischemia encephalopathy leading to external hydrocephalus and the cerebral atrophy: mechanism and differential diagnosis

    International Nuclear Information System (INIS)

    Huang Zhenglin; Mo Xiaorong

    2002-01-01

    Objective: It is a study of the mechanism and differential diagnosis of the infant external hydrocephalus and cerebral atrophy. Methods: In total 84 cases of neonatal hypoxic ischemia encephalopathy followed by infant external hydrocephalus were investigated, among which 26 patients gradually were found having developed cerebral atrophy in follow up. Results: Characteristic dilation of the frontal-parietal subarachnoid space and the adjacent cistern was noted on the CT images of the external hydrocephalus. CT revealed the enlarged ventricle besides the dilated subarachnoid space in the cases of cerebral atrophy, while these two entities were indistinguishable on CT in the early stage. Conclusion: Clinical manifestations make a major differential diagnosis of the external hydrocephalus and cerebral atrophy: tic and mild delayed development of locomotion over major presentation of external hydrocephalus, while cerebral atrophy is featured by remarkable dysnoesia and severe delayed development of locomotion. In addition, hemiplegia and increased muscular tension are presented in a few cases of cerebral atrophy

  4. Nontraumatic Fracture of the Femoral Condylar Prosthesis in a Total Knee Arthroplasty Leading to Mechanical Failure

    Directory of Open Access Journals (Sweden)

    Girish N. Swamy

    2014-01-01

    Full Text Available This paper reports a case of fatigue fracture of the femoral component in a cruciate-retaining cemented total knee arthroplasty (TKA. A 64-year-old man had undergone a primary TKA for osteoarthritis 10 years previously at another institution using the PFC-Sigma prosthesis. The patient recovered fully and was back to his regular activities. He presented with a history of sudden onset pain and locking of the left knee since the preceding three months. There was no history of trauma, and the patient was mobilizing with difficulty using crutches. Radiographs revealed fracture of the posterior condyle of the femoral prosthesis. Revision surgery was performed as an elective procedure revealing the broken prosthesis. The TC3RP-PFC revision prosthesis was used with a medial parapatellar approach. The patient recovered fully without any squeal. Mechanical failure of the knee arthroplasty prosthesis is rare, and nontraumatic fracture of the femoral metallic component has not been reported before.

  5. Nontraumatic fracture of the femoral condylar prosthesis in a total knee arthroplasty leading to mechanical failure.

    Science.gov (United States)

    Swamy, Girish N; Quah, Conal; Bagouri, Elmunzar; Badhe, Nitin P

    2014-01-01

    This paper reports a case of fatigue fracture of the femoral component in a cruciate-retaining cemented total knee arthroplasty (TKA). A 64-year-old man had undergone a primary TKA for osteoarthritis 10 years previously at another institution using the PFC-Sigma prosthesis. The patient recovered fully and was back to his regular activities. He presented with a history of sudden onset pain and locking of the left knee since the preceding three months. There was no history of trauma, and the patient was mobilizing with difficulty using crutches. Radiographs revealed fracture of the posterior condyle of the femoral prosthesis. Revision surgery was performed as an elective procedure revealing the broken prosthesis. The TC3RP-PFC revision prosthesis was used with a medial parapatellar approach. The patient recovered fully without any squeal. Mechanical failure of the knee arthroplasty prosthesis is rare, and nontraumatic fracture of the femoral metallic component has not been reported before.

  6. Genetic mechanisms leading to primary amenorrhea in balanced X-autosome translocations.

    Science.gov (United States)

    Moysés-Oliveira, Mariana; Guilherme, Roberta Dos Santos; Dantas, Anelisa Gollo; Ueta, Renata; Perez, Ana Beatriz; Haidar, Mauro; Canonaco, Rosane; Meloni, Vera Ayres; Kosyakova, Nadezda; Liehr, Thomas; Carvalheira, Gianna Maria; Melaragno, Maria Isabel

    2015-05-01

    To map the X-chromosome and autosome breakpoints in women with balanced X-autosome translocations and primary amenorrhea, searching candidate genomic loci for female infertility. Retrospective and case-control study. University-based research laboratory. Three women with balanced X-autosome translocation and primary amenorrhea. Conventional cytogenetic methods, genomic array, array painting, fluorescence in situ hybridization, and quantitative reverse transcription-polymerase chain reaction. Karyotype, copy number variation, breakpoint mapping, and gene expression levels. All patients presented with breakpoints in the Xq13q21 region. In two patients, the X-chromosome breakpoint disrupted coding sequences (KIAA2022 and ZDHHC15 genes). Although both gene disruptions caused absence of transcription in peripheral blood, there is no evidence that supports the involvement of these genes with ovarian function. The ZDHHC15 gene belongs to a conserved syntenic region that encompasses the FGF16 gene, which plays a role in female germ line development. The break in the FGF16 syntenic block may have disrupted the interaction between the FGF16 promoter and its cis-regulatory element. In the third patient, although both breakpoints are intergenic, a gene that plays a role in the DAX1 pathway (FHL2 gene) flanks distally the autosome breakpoint. The FHL2 gene may be subject to position effect due to the attachment of an autosome segment in Xq21 region. The etiology of primary amenorrhea in balanced X-autosome translocation patients may underlie more complex mechanisms than interruption of specific X-linked candidate genes, such as position effect. The fine mapping of the rearrangement breakpoints may be a tool for identifying genetic pathogenic mechanisms for primary amenorrhea. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  7. In case of obesity, longevity-related mechanisms lead to anti-inflammation.

    Science.gov (United States)

    Kaya, Mehmet Salih; Bayıroglu, Fahri; Mis, Leyla; Kilinc, Dide; Comba, Bahat

    2014-04-01

    The exact mechanisms which contribute to longevity have not been figured out yet. Our aim was to find out a common way for prompting longevity by bringing together the well-known applications such as food restriction, exercise, and probiotic supplementing in an experimental obesity model. Experimental obesity was promoted in a total of 32 young (2 months old) and 32 aged (16 months old) male Wistar albino rats through 8-week cafeteria diet (salami, chocolate, chips, and biscuits). Old and young animals were divided into groups each consisting of eight animals and also divided into four subgroups as obese control, obese food restriction, obese probiotic-fed and obese exercise groups. Probiotic group diet contained 0.05 %w/total diet inactive and lyophilized Lactobacillus casei str. Shirota. The exercise group was subjected to treadmill running 1 h/day, at 21 m/min and at an uphill incline of 15 % for 5 days a week. Food restriction group was formed by giving 40 % less food than the others. The control group was fed regular pellet feed ad libitum. This program was continued for 16 weeks. Blood samples from all the groups were analyzed for fasting glucose, insulin, IGF-1, insulin-like growth factor binding protein 3 (IGFBP-3), interleukin (IL)-6, IL-12, malondialdehyde (MDA), fT3, TT3, fT4, TT4, and liver tissue MDA levels were measured. All applications showed anti-inflammatory effects through the observed changes in the levels of IGFBP-3, IL-6, and IL-12 in the young and old obese rats. While the interventions normally contribute to longevity by recruiting different action mechanisms, anti-inflammatory effect is the only mode of action for all the applications in the obesity model.

  8. A literature survey of the biological effects and mechanics of electromagnetic radiation

    International Nuclear Information System (INIS)

    Zeh, K.A.

    1985-01-01

    The following report discusses the very controversial subject of electromagnetic interaction with the human body. The project was undertaken in the form of a literature survey to investigate the biological mechanisms responsible for the interaction, the theoretical models and associated mathematical techniques required to model the human body, the resulting energy deposition in the human and the factors which effect this. It was established that at present the most realistic model of man can be obtained using a block model and moment method technique with improved methods such as conjugate gradients or band approximation for the necessary matrix inversion. The impedance method of modelling could be very promising for future research. From the literature studied on biological effects no scientific evidence was found which definitely proves or disproves hazardous effects exist at low field intensities ( -2 ). The testes and the lens of the eye can be harmed, however, if the intensity is sufficient to cause a temperature rise of 1 degree Celsius in these organs

  9. Dysfunctional Hematopoietic Stem Cell Biology: Underlying Mechanisms and Potential Therapeutic Strategies

    Directory of Open Access Journals (Sweden)

    Anja Geiselhart

    2012-01-01

    Full Text Available Fanconi anemia (FA is the most common inherited bone marrow failure syndrome. FA patients suffer to varying degrees from a heterogeneous range of developmental defects and, in addition, have an increased likelihood of developing cancer. Almost all FA patients develop a severe, progressive bone marrow failure syndrome, which impacts upon the production of all hematopoietic lineages and, hence, is thought to be driven by a defect at the level of the hematopoietic stem cell (HSC. This hypothesis would also correlate with the very high incidence of MDS and AML that is observed in FA patients. In this paper, we discuss the evidence that supports the role of dysfunctional HSC biology in driving the etiology of the disease. Furthermore, we consider the different model systems currently available to study the biology of cells defective in the FA signaling pathway and how they are informative in terms of identifying the physiologic mediators of HSC depletion and dissecting their putative mechanism of action. Finally, we ask whether the insights gained using such disease models can be translated into potential novel therapeutic strategies for the treatment of the hematologic disorders in FA patients.

  10. Screening of biologically important Zn2 + by a chemosensor with fluorescent turn on-off mechanism

    Science.gov (United States)

    Khan, Tanveer A.; Sheoran, Monika; Nikhil Raj M., Venkata; Jain, Surbhi; Gupta, Diksha; Naik, Sunil G.

    2018-01-01

    Reported herein the synthesis, characterization and biologically important zinc ion binding propensity of a weakly fluorescent chemosensor, 4-methyl-2,6-bis((E)-(2-(4-phenylthiazol-2-yl)hydrazono)methyl)phenol (1). 1H NMR spectroscopic titration experiment reveals the binding knack of 1 to the essential Zn2 +. The photo-physical studies of 1 exhibit an enhancement in the fluorescence by several folds upon binding with the zinc ions attributed to PET-off process, with a binding constant value of 5.22 × 103 M- 1. 1 exhibits an excellent detection range for Zn2 + with lower detection limit value of 2.31 × 10- 8 M. The selectivity of 1 was studied with various mono and divalent metal cations and it was observed that most cations either quenches the fluorescence or remains unchanged except for Cd2 +, which shows a slight enhancement in fluorescence intensity of 1. The ratiometric displacement of Cd2 + ions by Zn2 + ions shows an excellent selectivity towards in-situ detection of Zn2 + ions. Photo-physical studies also support the reversible binding of 1 to Zn2 + ions having on and off mechanism in presence of EDTA. Such recognition of the biologically important zinc ions finds potential application in live cell imaging.

  11. Heavy-ion radiobiology: new approaches to delineate mechanisms underlying enhanced biological effectiveness

    Science.gov (United States)

    Blakely, E. A.; Kronenberg, A.; Chatterjee, A. (Principal Investigator)

    1998-01-01

    Shortly after the discovery of polonium and radium by Marie Curie and her husband and colleague, Pierre Curie, it was learned that exposure to these alpha-particle emitters produced deleterious biological effects. The mechanisms underlying the increased biological effectiveness of densely ionizing radiations, including alpha particles, neutrons and highly energetic heavy charged particles, remain an active area of investigation. In this paper, we review recent advances in several areas of the radiobiology of these densely ionizing radiations, also known as heavy ions. Advances are described in the areas of DNA damage and repair, chromosome aberrations, mutagenesis, neoplastic transformation in vitro, genomic instability, normal tissue radiobiology and carcinogenesis in vivo. We focus on technical innovations, including novel applications of pulsed-field gel electrophoresis, fluorescence in situ hybridization (FISH), linkage analysis, and studies of gene expression and protein expression. We also highlight the use of new cellular and animal systems, including those with defined DNA repair deficiencies, as well as epithelial cell model systems to assess neoplastic transformation both in vitro and in vivo. The studies reviewed herein have had a substantial impact on our understanding of the genotoxic effects of heavy ions as well as their distinct effects on tissue homeostasis. The use of these radiations in cancer therapy is also discussed. The use of both heavy-ion and proton therapy is on the upswing in several centers around the world, due to their unique energy deposition characteristics that enhance the therapeutic effect and help reduce damage to normal tissue.

  12. Beyond COX-1: the effects of aspirin on platelet biology and potential mechanisms of chemoprevention.

    Science.gov (United States)

    Ornelas, Argentina; Zacharias-Millward, Niki; Menter, David G; Davis, Jennifer S; Lichtenberger, Lenard; Hawke, David; Hawk, Ernest; Vilar, Eduardo; Bhattacharya, Pratip; Millward, Steven

    2017-06-01

    After more than a century, aspirin remains one of the most commonly used drugs in western medicine. Although mainly used for its anti-thrombotic, anti-pyretic, and analgesic properties, a multitude of clinical studies have provided convincing evidence that regular, low-dose aspirin use dramatically lowers the risk of cancer. These observations coincide with recent studies showing a functional relationship between platelets and tumors, suggesting that aspirin's chemopreventive properties may result, in part, from direct modulation of platelet biology and biochemistry. Here, we present a review of the biochemistry and pharmacology of aspirin with particular emphasis on its cyclooxygenase-dependent and cyclooxygenase-independent effects in platelets. We also correlate the results of proteomic-based studies of aspirin acetylation in eukaryotic cells with recent developments in platelet proteomics to identify non-cyclooxygenase targets of aspirin-mediated acetylation in platelets that may play a role in its chemopreventive mechanism.

  13. Intended process water management concept for the mechanical biological treatment of municipal solid waste

    Institute of Scientific and Technical Information of China (English)

    D. Weichgrebe; S. Maerker; T. Boning; H. Stegemann

    2008-01-01

    Accumulating operational experience in both aerobic and anaerobic mechanical biological waste treatment (MBT) makes it increasingly obvious that controlled water management would substantially reduce the cost of MBT and also enhance resource recovery of the organic and inorganic fraction. The MBT plant at Gescher, Germany, is used as an example in order to determine the quantity and composition of process water and leachates from intensive and subsequent rotting, pressing water from anaerobic digestion and scrubber water from acid exhaust air treatment, and hence prepare an MBT water balance. The potential of, requirements for and limits to internal process water reuse as well as the possibilities of resource recovery from scrubber water are also examined. Finally, an assimilated process water management concept with the purpose of an extensive reduction of wastewater quantity and freshwater demand is presented.

  14. Fracture mechanisms in ferroelectric-ferroelastic lead zirconate titanate (Zr:Ti = 0.54:0.46) ceramics

    International Nuclear Information System (INIS)

    Mehta, K.; Virkar, A.V.

    1990-01-01

    Fracture toughness, K IC , of a single-phase commercial lead zirconate titanate (PZT) ceramic of tetragonal structure was measured using the single edge notched beam method above and below the Curie temperature. Domain switching (poling) under electrical and mechanical loading was examined using x-ray diffraction. Surface grinding, electrical poling, and mechanical poling caused crystallographic texture. Similar texture, indicative of domain switching, was also observed on fracture surfaces of some samples fractured at room temperature. At room temperature, the highest K IC measured was 1.85 MPa · m 1/2 , while above the Curie temperature it was about 1.0 MPa · m 1/2 . Cracks emanating from Vickers indents in poled samples were different in the poling and the transverse directions. The difference in crack sizes is explained on the basis of domain switching during crack growth. These results indicate that ferroelastic domain switching (twinning) is a viable toughening mechanism in the PZT materials tested

  15. Shear strength characteristics of mechanically biologically treated municipal solid waste (MBT-MSW) from Bangalore

    International Nuclear Information System (INIS)

    Sivakumar Babu, G.L.; Lakshmikanthan, P.; Santhosh, L.G.

    2015-01-01

    Highlights: • Shear strength properties of mechanically biologically treated municipal solid waste. • Effect of unit weight and particle size on the shear strength of waste. • Effect of particle size on the strength properties. • Stiffness ratio and the strength ratio of MSW. - Abstract: Strength and stiffness properties of municipal solid waste (MSW) are important in landfill design. This paper presents the results of comprehensive testing of shear strength properties of mechanically biologically treated municipal solid waste (MBT-MSW) in laboratory. Changes in shear strength of MSW as a function of unit weight and particle size were investigated by performing laboratory studies on the MSW collected from Mavallipura landfill site in Bangalore. Direct shear tests, small scale and large scale consolidated undrained and drained triaxial tests were conducted on reconstituted compost reject MSW samples. The triaxial test results showed that the MSW samples exhibited a strain-hardening behaviour and the strength of MSW increased with increase in unit weight. Consolidated drained tests showed that the mobilized shear strength of the MSW increased by 40% for a unit weight increase from 7.3 kN/m 3 to 10.3 kN/m 3 at 20% strain levels. The mobilized cohesion and friction angle ranged from 5 to 9 kPa and 8° to 33° corresponding to a strain level of 20%. The consolidated undrained tests exhibited reduced friction angle values compared to the consolidated drained tests. The friction angle increased with increase in the unit weight from 8° to 55° in the consolidated undrained tests. Minor variations were found in the cohesion values. Relationships for strength and stiffness of MSW in terms of strength and stiffness ratios are developed and discussed. The stiffness ratio and the strength ratio of MSW were found to be 10 and 0.43

  16. Geomagnetic polarity reversals as a mechanism for the punctuated equilibrium model of biological evolution

    International Nuclear Information System (INIS)

    Welsh, J.S.; Welsh, A.L.; Welsh, W.F.

    2003-01-01

    In contrast to what is predicted by classical Darwinian theory (phyletic gradualism), the fossil record typically displays a pattern of relatively sudden, dramatic changes as detailed by Eldregde and Gould's model of punctuated equilibrium. Evolutionary biologists have been at a loss to explain the ultimate source of the new mutations that drive evolution. One hypothesis holds that the abrupt speciation seen in the punctuated equilibrium model is secondary to an increased mutation rate resulting from periodically increased levels of ionizing radiation on the Earth's surface. Sporadic geomagnetic pole reversals, occurring every few million years on the average, are accompanied by alterations in the strength of the Earth's magnetic field and magnetosphere. This diminution may allow charged cosmic radiation to bombard Earth with less attenuation, thereby resulting in increased mutation rates. This episodic fluctuation in the magnetosphere is an attractive mechanism for the observed fossil record. Selected periods and epochs of geologic history for which data was available were reviewed for both geomagnetic pole reversal history and fossil record. Anomalies in either were scrutinized in greater depth and correlations were made. A 35 million year span (118-83 Ma) was identified during the Early/Middle Cretaceous period that was devoid of geomagnetic polarity reversals(the Cretaceous normal superchron). Examination of the fossil record (including several invertebrate and vertebrate taxons) during the Cretaceous normal superchron does not reveal any significant gap or slowing of speciation. Although increased terrestrial radiation exposure due to a diminution of the Earth's magnetosphere caused by a reversal of geomagnetic polarity is an attractive explanation for the mechanism of punctuated equilibrium, our investigation suggests that such polarity reversals cannot fully provide the driving force behind biological evolution. Further research is required to determine if

  17. Shear strength characteristics of mechanically biologically treated municipal solid waste (MBT-MSW) from Bangalore

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar Babu, G.L., E-mail: gls@civil.iisc.ernet.in [Department of Civil Engineering, Indian Institute of Science, Bangalore 560012 (India); Lakshmikanthan, P., E-mail: lakshmikanthancp@gmail.com [Centre for Sustainable Technologies (CST), Indian Institute of Science, Bangalore 560012 (India); Santhosh, L.G., E-mail: lgsanthu2006@gmail.com [Centre for Sustainable Technologies (CST), Indian Institute of Science, Bangalore 560012 (India)

    2015-05-15

    Highlights: • Shear strength properties of mechanically biologically treated municipal solid waste. • Effect of unit weight and particle size on the shear strength of waste. • Effect of particle size on the strength properties. • Stiffness ratio and the strength ratio of MSW. - Abstract: Strength and stiffness properties of municipal solid waste (MSW) are important in landfill design. This paper presents the results of comprehensive testing of shear strength properties of mechanically biologically treated municipal solid waste (MBT-MSW) in laboratory. Changes in shear strength of MSW as a function of unit weight and particle size were investigated by performing laboratory studies on the MSW collected from Mavallipura landfill site in Bangalore. Direct shear tests, small scale and large scale consolidated undrained and drained triaxial tests were conducted on reconstituted compost reject MSW samples. The triaxial test results showed that the MSW samples exhibited a strain-hardening behaviour and the strength of MSW increased with increase in unit weight. Consolidated drained tests showed that the mobilized shear strength of the MSW increased by 40% for a unit weight increase from 7.3 kN/m{sup 3} to 10.3 kN/m{sup 3} at 20% strain levels. The mobilized cohesion and friction angle ranged from 5 to 9 kPa and 8° to 33° corresponding to a strain level of 20%. The consolidated undrained tests exhibited reduced friction angle values compared to the consolidated drained tests. The friction angle increased with increase in the unit weight from 8° to 55° in the consolidated undrained tests. Minor variations were found in the cohesion values. Relationships for strength and stiffness of MSW in terms of strength and stiffness ratios are developed and discussed. The stiffness ratio and the strength ratio of MSW were found to be 10 and 0.43.

  18. Transmission electron microscopy investigation of the microstructural mechanisms for the piezoelectricity in lead-free perovskite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Cheng [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Lead-free materials with superior piezoelectricity are in increasingly urgent demand in the current century, because the industrial standard Pb(Zr,Ti)O3-based piezoelectrics, which contain over 60 weight% of the toxic element lead, pose severe environmental hazards. Although significant research efforts have been devoted in the past decade, no effective lead-free substitute for Pb(Zr,Ti)O3 has been identified yet. One of the primary hindrances to the development of lead-free piezoelectrics lies in the ignorance of the microstructural mechanism for the electric-field-induced strains in the currently existing compositions. In this dissertation, the microstructural origin for the high piezoelectricity in (1-x)(Bi1/2Na1/2)TiO3-xBaTiO3 [(1-x)BNT-xBT], the most widely studied lead-free piezoelectric system, has been elucidated.

  19. Membrane Interactions of Phytochemicals as Their Molecular Mechanism Applicable to the Discovery of Drug Leads from Plants

    Directory of Open Access Journals (Sweden)

    Hironori Tsuchiya

    2015-10-01

    Full Text Available In addition to interacting with functional proteins such as receptors, ion channels, and enzymes, a variety of drugs mechanistically act on membrane lipids to change the physicochemical properties of biomembranes as reported for anesthetic, adrenergic, cholinergic, non-steroidal anti-inflammatory, analgesic, antitumor, antiplatelet, antimicrobial, and antioxidant drugs. As well as these membrane-acting drugs, bioactive plant components, phytochemicals, with amphiphilic or hydrophobic structures, are presumed to interact with biological membranes and biomimetic membranes prepared with phospholipids and cholesterol, resulting in the modification of membrane fluidity, microviscosity, order, elasticity, and permeability with the potencies being consistent with their pharmacological effects. A novel mechanistic point of view of phytochemicals would lead to a better understanding of their bioactivities, an insight into their medicinal benefits, and a strategic implication for discovering drug leads from plants. This article reviews the membrane interactions of different classes of phytochemicals by highlighting their induced changes in membrane property. The phytochemicals to be reviewed include membrane-interactive flavonoids, terpenoids, stilbenoids, capsaicinoids, phloroglucinols, naphthodianthrones, organosulfur compounds, alkaloids, anthraquinonoids, ginsenosides, pentacyclic triterpene acids, and curcuminoids. The membrane interaction’s applicability to the discovery of phytochemical drug leads is also discussed while referring to previous screening and isolating studies.

  20. Absence of alsin function leads to corticospinal motor neuron vulnerability via novel disease mechanisms.

    Science.gov (United States)

    Gautam, Mukesh; Jara, Javier H; Sekerkova, Gabriella; Yasvoina, Marina V; Martina, Marco; Özdinler, P Hande

    2016-03-15

    Mutations in the ALS2 gene result in early-onset amyotrophic lateral sclerosis, infantile-onset ascending hereditary spastic paraplegia and juvenile primary lateral sclerosis, suggesting prominent upper motor neuron involvement. However, the importance of alsin function for corticospinal motor neuron (CSMN) health and stability remains unknown. To date, four separate alsin knockout (Alsin(KO)) mouse models have been generated, and despite hopes of mimicking human pathology, none displayed profound motor function defects. This, however, does not rule out the possibility of neuronal defects within CSMN, which is not easy to detect in these mice. Detailed cellular analysis of CSMN has been hampered due to their limited numbers and the complex and heterogeneous structure of the cerebral cortex. In an effort to visualize CSMN in vivo and to investigate precise aspects of neuronal abnormalities in the absence of alsin function, we generated Alsin(KO)-UeGFP mice, by crossing Alsin(KO) and UCHL1-eGFP mice, a CSMN reporter line. We find that CSMN display vacuolated apical dendrites with increased autophagy, shrinkage of soma size and axonal pathology even in the pons region. Immunocytochemistry coupled with electron microscopy reveal that alsin is important for maintaining cellular cytoarchitecture and integrity of cellular organelles. In its absence, CSMN displays selective defects both in mitochondria and Golgi apparatus. UCHL1-eGFP mice help understand the underlying cellular factors that lead to CSMN vulnerability in diseases, and our findings reveal unique importance of alsin function for CSMN health and stability. © The Author 2016. Published by Oxford University Press.

  1. [Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

    Science.gov (United States)

    Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

    2014-08-01

    Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

  2. Ferroelectric behavior of a lead titanate nanosphere due to depolarization fields and mechanical stresses

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Landeta, J.; Lascano, I.

    2017-07-01

    A theorical model has been developed based on the theory of Ginzburg-Landau-Devonshire to study and predict the effects the decreasing of size particle in a nanosphere of PbTiO3 subjected to the action of depolarization fields and mechanical stress. It was considered that the nanosphere is surrounded by a layer of space charges on its surface, and containing 180° domains generated by minimizing free energy of depolarization. Energy density of depolarization, wall domain and electro-elastic energy have been incorporated into the free energy of the theory Ginzburg-Landau-Devonshire. Free energy minimization was performed to determine the spontaneous polarization and transition temperature system. These results show that the transition temperature for nanosphere is substantially smaller than the corresponding bulk material. Also, it has been obtained that the stability of the ferroelectric phase of nanosphere is favored for configurations with a large number of 180° domains, with the decreasing of thickness space charge layer, and the application of tensile stress and decreases with compressive stress. (Author)

  3. Mechanism of Supercooled Water Droplet Breakup near the Leading Edge of an Airfoil

    Science.gov (United States)

    Veras-Alba, Belen; Palacios, Jose; Vargas, Mario; Ruggeri, Charles; Bartkus, Tadas P.

    2017-01-01

    This work presents the results of an experimental study on supercooled droplet deformation and breakup near the leading edge of an airfoil. The results are compared to prior room temperature droplet deformation results to explore the effects of droplet supercooling. The experiments were conducted in the Adverse Environment Rotor Test Stand (AERTS) at The Pennsylvania State University. An airfoil model placed at the end of the rotor blades mounted onto the hub in the AERTS chamber was moved at speeds ranging between 50 and 80 m/sec. The temperature of the chamber was set at -20°C. A monotonic droplet generator was used to produce droplets that fell from above, perpendicular to the path of the airfoil. The supercooled state of the droplets was determined by measurement of the temperature of the drops at various locations below the droplet generator exit. A temperature prediction code was also used to estimate the temperature of the droplets based on vertical velocity and the distance traveled by droplets from the droplet generator to the airfoil stagnation line. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging provided droplet deformation information as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure the horizontal and vertical displacement of the droplet against time. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the ratio of the slip velocity and the initial droplet velocity must be equal. A case with equal slip velocity to initial velocity ratios was selected for room temperature and supercooled droplet conditions. The airfoil velocity was 60 m/s and the slip velocity for both sets of data was 40 m/s. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends. The similar behavior for both environmental conditions indicates that water

  4. Molecular Mechanisms of Glutamine Synthetase Mutations that Lead to Clinically Relevant Pathologies.

    Directory of Open Access Journals (Sweden)

    Benedikt Frieg

    2016-02-01

    Full Text Available Glutamine synthetase (GS catalyzes ATP-dependent ligation of ammonia and glutamate to glutamine. Two mutations of human GS (R324C and R341C were connected to congenital glutamine deficiency with severe brain malformations resulting in neonatal death. Another GS mutation (R324S was identified in a neurologically compromised patient. However, the molecular mechanisms underlying the impairment of GS activity by these mutations have remained elusive. Molecular dynamics simulations, free energy calculations, and rigidity analyses suggest that all three mutations influence the first step of GS catalytic cycle. The R324S and R324C mutations deteriorate GS catalytic activity due to loss of direct interactions with ATP. As to R324S, indirect, water-mediated interactions reduce this effect, which may explain the suggested higher GS residual activity. The R341C mutation weakens ATP binding by destabilizing the interacting residue R340 in the apo state of GS. Additionally, the mutation is predicted to result in a significant destabilization of helix H8, which should negatively affect glutamate binding. This prediction was tested in HEK293 cells overexpressing GS by dot-blot analysis: Structural stability of H8 was impaired through mutation of amino acids interacting with R341, as indicated by a loss of masking of an epitope in the glutamate binding pocket for a monoclonal anti-GS antibody by L-methionine-S-sulfoximine; in contrast, cells transfected with wild type GS showed the masking. Our analyses reveal complex molecular effects underlying impaired GS catalytic activity in three clinically relevant mutants. Our findings could stimulate the development of ATP binding-enhancing molecules by which the R324S mutant can be repaired extrinsically.

  5. Effects and mechanisms of meta-sodium silicate amendments on lead uptake and accumulation by rice.

    Science.gov (United States)

    Zhao, Mingliu; Liu, Yuting; Li, Honghong; Cai, Yifan; Wang, Ming Kuang; Chen, Yanhui; Xie, Tuanhui; Wang, Guo

    2017-09-01

    The objectives of this research were to study the effects of Na 2 SiO 3 application on the uptake, translocation, and accumulation of Pb in rice and to investigate the mechanisms of Pb immobilization by Na 2 SiO 3 in paddy rice soils and rice plants. Pot experiments were conducted using a Cd-Pb-Zn-polluted soil and Oryza sativa L. ssp. indica cv. Donglian 5. L 3 -edge X-ray absorption spectroscopy was used to identify Pb species in soils and roots. The results showed that the application of Na 2 SiO 3 increased soil pH and available soil Si but decreased DTPA-extractable Pb in the soil. High dose of Na 2 SiO 3 (12.5 g/kg) reduced the Pb level in brown rice as it inhibited Pb transfer from soil to rice grains, especially Pb transfer from the root to the stem. The Pb X-ray absorption near-edge spectroscopic analysis revealed that application of high dose of Na 2 SiO 3 increased Pb-ferrihydrite and PbSiO 3 precipitates in the soil and in the root while it reduced Pb-humic acids (Pb-HAs) in the soil and Pb-pectin in the root. The decrease in Pb availability in the soil can be partly attributed to increase the precipitation of PbSiO 3 and the association of Pb 2+ with Fe oxides in the soil. The inhibition of the root-to-stem translocation of Pb was partially due to the precipitation of PbSiO 3 on the root surfaces or inside the roots.

  6. Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: Mechanisms involved for lead

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, E., E-mail: eva.schreck@ensat.fr [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); Foucault, Y. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France); STCM, Societe de Traitements Chimiques des Metaux, 30 Avenue de Fondeyre 31200 Toulouse (France); Sarret, G. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Sobanska, S. [LASIR (UMR CNRS 8516), Universite de Lille 1, Bat. C5, 59655 Villeneuve d' Ascq cedex (France); Cecillon, L. [ISTerre (UMR 5275), Universite J. Fourier and CNRS, BP 53, 38041 Grenoble cedex 9 (France); Castrec-Rouelle, M. [Universite Pierre and Marie Curie (UPMC-Paris 6), Bioemco (Biogeochimie et Ecologie des Milieux Continentaux), Site Jussieu, Tour 56, 4 Place Jussieu, 75252 Paris cedex 05 (France); Uzu, G. [Laboratoire d' Aerologie (UMR 5560), OMP, UPS 14, Avenue Edouard Belin, 31400 Toulouse (France); GET (UMR 5563), IRD, 14, Avenue Edouard Belin, 31400 Toulouse (France); Dumat, C. [Universite de Toulouse (France); INP, UPS (France); EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement) (France); ENSAT, Avenue de l' Agrobiopole, 31326 Castanet Tolosan (France); CNRS (France); EcoLab, 31326 Castanet Tolosan (France)

    2012-06-15

    Fine and ultrafine metallic particulate matters (PMs) are emitted from metallurgic activities in peri-urban zones into the atmosphere and can be deposited in terrestrial ecosystems. The foliar transfer of metals and metalloids and their fate in plant leaves remain unclear, although this way of penetration may be a major contributor to the transfer of metals into plants. This study focused on the foliar uptake of various metals and metalloids from enriched PM (Cu, Zn, Cd, Sn, Sb, As, and especially lead (Pb)) resulting from the emissions of a battery-recycling factory. Metal and metalloid foliar uptake by various vegetable species, exhibiting different morphologies, use (food or fodder) and life-cycle (lettuce, parsley and rye-grass) were studied. The mechanisms involved in foliar metal transfer from atmospheric particulate matter fallout, using lead (Pb) as a model element was also investigated. Several complementary techniques (micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive X-ray microanalysis and time-of-flight secondary ion mass spectrometry) were used to investigate the localization and the speciation of lead in their edible parts, i.e. leaves. The results showed lead-enriched PM on the surface of plant leaves. Biogeochemical transformations occurred on the leaf surfaces with the formation of lead secondary species (PbCO{sub 3} and organic Pb). Some compounds were internalized in their primary form (PbSO{sub 4}) underneath an organic layer. Internalization through the cuticle or penetration through stomata openings are proposed as two major mechanisms involved in foliar uptake of particulate matter. - Graphical abstract: Overall picture of performed observations and mechanisms potentially involved in lead foliar uptake. Highlights: Black-Right-Pointing-Pointer Foliar uptake of metallic particulate matter (PM) is of environmental and health concerns. Black-Right-Pointing-Pointer The leaf morphology influences the adsorption

  7. Mechanical, Corrosion and Biological Properties of Room-Temperature Sputtered Aluminum Nitride Films with Dissimilar Nanostructure

    Directory of Open Access Journals (Sweden)

    Cristina Besleaga

    2017-11-01

    Full Text Available Aluminum Nitride (AlN has been long time being regarded as highly interesting material for developing sensing applications (including biosensors and implantable sensors. AlN, due to its appealing electronic properties, is envisaged lately to serve as a multi-functional biosensing platform. Although generally exploited for its intrinsic piezoelectricity, its surface morphology and mechanical performance (elastic modulus, hardness, wear, scratch and tensile resistance to delamination, adherence to the substrate, corrosion resistance and cytocompatibility are also essential features for high performance sustainable biosensor devices. However, information about AlN suitability for such applications is rather scarce or at best scattered and incomplete. Here, we aim to deliver a comprehensive evaluation of the morpho-structural, compositional, mechanical, electrochemical and biological properties of reactive radio-frequency magnetron sputtered AlN nanostructured thin films with various degrees of c-axis texturing, deposited at a low temperature (~50 °C on Si (100 substrates. The inter-conditionality elicited between the base pressure level attained in the reactor chamber and crystalline quality of AlN films is highlighted. The potential suitability of nanostructured AlN (in form of thin films for the realization of various type of sensors (with emphasis on bio-sensors is thoroughly probed, thus unveiling its advantages and limitations, as well as suggesting paths to safely exploit the remarkable prospects of this type of materials.

  8. Mechanical sludge disintegration for the production of carbon source for biological nutrient removal.

    Science.gov (United States)

    Kampas, P; Parsons, S A; Pearce, P; Ledoux, S; Vale, P; Churchley, J; Cartmell, E

    2007-04-01

    The primary driver for a successful biological nutrient removal is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mgl(-1), for VFA and SCOD, respectively. The particle size was reduced from 65.5 to 9.3 microm after 15 min of disintegration with the simultaneous release of proteins (1550 mgl(-1)) and carbohydrates (307 mgl(-1)) indicating floc disruption and breakage. High performance size exclusion chromatography investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (>or=10 min or >or=9000 kJkg(-1)TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.

  9. The Role of Biologically Active Ingredients from Natural Drug Treatments for Arrhythmias in Different Mechanisms.

    Science.gov (United States)

    Li, Jie; Hu, Dan; Song, Xiaoli; Han, Tao; Gao, Yonghong; Xing, Yanwei

    2017-01-01

    Arrhythmia is a disease that is caused by abnormal electrical activity in the heart rate or rhythm. It is the major cause of cardiovascular morbidity and mortality. Although several antiarrhythmic drugs have been used in clinic for decades, their application is often limited by their adverse effects. As a result, natural drugs, which have fewer side effects, are now being used to treat arrhythmias. We searched for all articles on the role of biologically active ingredients from natural drug treatments for arrhythmias in different mechanisms in PubMed. This study reviews 19 natural drug therapies, with 18 active ingredient therapies, such as alkaloids, flavonoids, saponins, quinones, and terpenes, and two kinds of traditional Chinese medicine compound (Wenxin-Keli and Shensongyangxin), all of which have been studied and reported as having antiarrhythmic effects. The primary focus is the proposed antiarrhythmic mechanism of each natural drug agent. Conclusion . We stress persistent vigilance on the part of the provider in discussing the use of natural drug agents to provide a solid theoretical foundation for further research on antiarrhythmia drugs.

  10. Mechanical, Corrosion and Biological Properties of Room-Temperature Sputtered Aluminum Nitride Films with Dissimilar Nanostructure.

    Science.gov (United States)

    Besleaga, Cristina; Dumitru, Viorel; Trinca, Liliana Marinela; Popa, Adrian-Claudiu; Negrila, Constantin-Catalin; Kołodziejczyk, Łukasz; Luculescu, Catalin-Romeo; Ionescu, Gabriela-Cristina; Ripeanu, Razvan-George; Vladescu, Alina; Stan, George E

    2017-11-17

    Aluminum Nitride (AlN) has been long time being regarded as highly interesting material for developing sensing applications (including biosensors and implantable sensors). AlN, due to its appealing electronic properties, is envisaged lately to serve as a multi-functional biosensing platform. Although generally exploited for its intrinsic piezoelectricity, its surface morphology and mechanical performance (elastic modulus, hardness, wear, scratch and tensile resistance to delamination, adherence to the substrate), corrosion resistance and cytocompatibility are also essential features for high performance sustainable biosensor devices. However, information about AlN suitability for such applications is rather scarce or at best scattered and incomplete. Here, we aim to deliver a comprehensive evaluation of the morpho-structural, compositional, mechanical, electrochemical and biological properties of reactive radio-frequency magnetron sputtered AlN nanostructured thin films with various degrees of c -axis texturing, deposited at a low temperature (~50 °C) on Si (100) substrates. The inter-conditionality elicited between the base pressure level attained in the reactor chamber and crystalline quality of AlN films is highlighted. The potential suitability of nanostructured AlN (in form of thin films) for the realization of various type of sensors (with emphasis on bio-sensors) is thoroughly probed, thus unveiling its advantages and limitations, as well as suggesting paths to safely exploit the remarkable prospects of this type of materials.

  11. Radon as a medicine. Therapeutic effectiveness, biological mechanism and comparative risk assessment

    International Nuclear Information System (INIS)

    Deetjen, Peter; Falkenbach, Albrecht; Harder, Dietrich; Joeckel, Hans; Kaul, Alexander; Philipsborn, Henning von

    2014-01-01

    Proofs of the therapeutic efficiency of balneological radon applications administered to patients suffering from rheumatic diseases, investigations into the biological action mechanism associated with the alpha particles emitted by radon and its radioactive daughter products, and the comparative risk assessment of radon treatment and medicinal pain therapy have been the research projects whose results are summarized in this book. Controlled clinical studies, if possible performed as prospective, randomized and placebo-controlled double blind studies, have given evidence that the therapeutic effects of balneological radon applications - long-lasting pain reduction and reduced consumption of medicines compared with controls - are significantly persisting over many post-treatment months. The molecular and cellular mechanism of action underlying these long-lasting therapeutic effects has been identified as the down-regulation of cellular immune responses, initiated by cellular apoptosis sequential to low alpha particle doses and by the subsequent release of anti-inflammatory cytokines. The unwanted side-effects of non-steroidal anti-rheumatic drug treatments have to be compared with the absence of side effects from the balneological radon applications which merely involve radiation doses well below the mean value and the fluctuation width of the annual doses attributable to everybody's natural radiation exposure.

  12. Performance of mechanical biological treatment of residual municipal waste in Poland

    Science.gov (United States)

    den Boer, Emilia; Jędrczak, Andrzej

    2017-11-01

    The number and capacity of mechanical-biological treatment (MBT) plants in Europe increased significantly in the past two decades as a response to the legal obligation to limit the landfilling of biodegradable waste in landfills and to increase recycling and energy recovery from waste. The aim of these plants is to prepare residual municipal waste for recovery and disposal operations, including especially separation and stabilization of the easily biodegradable fraction (the biofraction). The final products of MBP technology are recyclables, stabilate, high calorific fraction which is used for the production of refuse derived fuel (RDF) and the remaining residual fraction. The shares of the output fractions, especially of the recyclables and RDF determine the overall efficiency of MBT technology in diverting waste from landfills. In this paper results of an assessment of one exemplary MBT plant are provided. The analysis was performed within a comparative study in which 20 selected MBT plants in Poland were subject to a detailed analysis, focusing, both at the design parameters as well as operational ones. The selected plant showed relatively higher overall materials recovery efficiency. With the view to circular economy targets, increased automation of the mechanical waste treatment will be required to support achieving high level diversion from landfills. The study reviled that stabilisation of biofraction should be improved by a better control of process conditions, especially moisture content.

  13. Radon as a medicine. Therapeutic effectiveness, biological mechanism and comparative risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Deetjen, Peter; Falkenbach, Albrecht; Harder, Dietrich; Joeckel, Hans; Kaul, Alexander; Philipsborn, Henning von

    2014-07-01

    Proofs of the therapeutic efficiency of balneological radon applications administered to patients suffering from rheumatic diseases, investigations into the biological action mechanism associated with the alpha particles emitted by radon and its radioactive daughter products, and the comparative risk assessment of radon treatment and medicinal pain therapy have been the research projects whose results are summarized in this book. Controlled clinical studies, if possible performed as prospective, randomized and placebo-controlled double blind studies, have given evidence that the therapeutic effects of balneological radon applications - long-lasting pain reduction and reduced consumption of medicines compared with controls - are significantly persisting over many post-treatment months. The molecular and cellular mechanism of action underlying these long-lasting therapeutic effects has been identified as the down-regulation of cellular immune responses, initiated by cellular apoptosis sequential to low alpha particle doses and by the subsequent release of anti-inflammatory cytokines. The unwanted side-effects of non-steroidal anti-rheumatic drug treatments have to be compared with the absence of side effects from the balneological radon applications which merely involve radiation doses well below the mean value and the fluctuation width of the annual doses attributable to everybody's natural radiation exposure.

  14. Radiation-induced secretory protein, clusterin. Its inductive mechanism and biological significance

    International Nuclear Information System (INIS)

    Suzuki, Masatoshi; Boothman, D.A.

    2007-01-01

    This paper describes biochemistry of secretory clusterin (C), its radiation-inductive mechanism and biological significance. C is a glycoprotein found to be secreted from cells given various stresses like radiation and ultraviolet (UV)-ray, and participates to red cell clustering. Human C gene locates on the chromosome 8p21-p12, C has MW of 60 kDa, its precursor undergoes the degrading processing to α- and β-chains to form their heterodimer before glycosylation, and the C is finally secreted. So many other names have been given to C due to its numerous functions which have been discovered in other fields, such as apolipoprotein J. C is abundant in plasma, milk, urine, cerebrospinal fluid, semen, etc. Within 24 hr after X-ray irradiation, extracellular insulin-like growth factor-1 (IGF-1) level is elevated, and through its binding to the receptor, Src/MAPK signaling participates to C expression. Nuclear C, also induced by radiation, is a splicing variant of C and not secreted from cells. C is induced by radiation with as low dose as 2 cGy, which is different from induction of nuclear C. Secreted C is incorporated in cells by endocytosis and promotes the intracellular survival reaction through IGF-1 receptor/MAPK/Egr-1 pathway, whereas nuclear C induces cell apoptosis via unknown mechanism. Further studies are required for elucidation of the roles of secretory and nuclear C in cellular radiation responses. (R.T.)

  15. Elevated-Temperature Mechanical Properties of Lead-Free Sn-0.7Cu- xSiC Nanocomposite Solders

    Science.gov (United States)

    Mohammadi, A.; Mahmudi, R.

    2018-02-01

    Mechanical properties of Sn-0.7 wt.%Cu lead-free solder alloy reinforced with 0 vol.%, 1 vol.%, 2 vol.%, and 3 vol.% 100-nm SiC particles have been assessed using the shear punch testing technique in the temperature range from 25°C to 125°C. The composite materials were fabricated by the powder metallurgy route by blending, compacting, sintering, and finally extrusion. The 2 vol.% SiC-containing composite showed superior mechanical properties. In all conditions, the shear strength was adversely affected by increasing test temperature, and the 2 vol.% SiC-containing composite showed superior mechanical properties. Depending on the test temperature, the shear yield stress and ultimate shear strength increased, respectively, by 3 MPa to 4 MPa and 4 MPa to 5.5 MPa, in the composite materials. The strength enhancement was mostly attributed to the Orowan particle strengthening mechanism due to the SiC nanoparticles, and to a lesser extent to the coefficient of thermal expansion mismatch between the particles and matrix in the composite solder. A modified shear lag model was used to predict the total strengthening achieved by particle addition, based on the contribution of each of the above mechanisms.

  16. Molecular binding mechanisms of aqueous cadmium and lead to siderophores, bacteria and mineral surfaces

    Science.gov (United States)

    Mishra, Bhoopesh

    Recent studies have shown that diverse groups of bacteria adsorb metals to similar extents and uptake can be modeled using a universal adsorption model. In this study, XAFS has been used to resolve whether binding sites determined for single species systems are responsible for adsorption in more complex natural bacterial assemblages. Results obtained from a series of XAFS experiments on pure Gram positive and Gram negative bacterial strains and consortia of bacteria as a function of pH and Cd loading suggests that every bacterial strain has a complex physiology and they are all slightly different from each other. Nevertheless from the metal adsorption chemistry point of view, the main difference between them lies in the site ratio of three fundamental sites only - carboxyl, phosphoryl and sulfide. Two completely different consortia of bacteria (obtained from natural river water, and soil system with severe organic contamination) were successfully modeled in the pH range 3.4--7.8 using the EXAFS models developed for single species systems. Results thus obtained can potentially have very high impact on the modeling of the complex bacterial systems in realistic geological settings, leading to further refinement and development of robust remediation strategies for metal contamination at macroscopic level. In another study, solution speciation of Pb and Cd with DFO-B has been examined using a combination of techniques (ICP, TOC, thermodynamic modeling and XAFS). Results indicate that Pb does not complex with DFO-B at all until about pH 3.5, but forms a totally caged structure at pH 7.5. At intermediate pH conditions, mixture of species (one and two hydroxamate groups complexed) is formed. Cd on the other hand, does not complex until pH 5, forms intermediate complexes at pH 8 and is totally chelated at pH 9. Further studies were conducted for Pb sorption to mineral surface kaolinite with and without DFO-B. In the absence of DFO-B, results suggest outer sphere and inner

  17. Wind Climate in Kongsfjorden, Svalbard, and Attribution of Leading Wind Driving Mechanisms through Turbulence-Resolving Simulations

    Directory of Open Access Journals (Sweden)

    Igor Esau

    2012-01-01

    Full Text Available This paper presents analysis of wind climate of the Kongsfjorden-Kongsvegen valley, Svalbard. The Kongsfjorden-Kongsvegen valley is relatively densely covered with meteorological observations, which facilitate joint statistical analysis of the turbulent surface layer structure and the structure of the higher atmospheric layers. Wind direction diagrams reveal strong wind channeled in the surface layer up to 300 m to 500 m. The probability analysis links strong wind channeling and cold temperature anomalies in the surface layer. To explain these links, previous studies suggested the katabatic wind flow mechanism as the leading driver responsible for the observed wind climatology. In this paper, idealized turbulence-resolving simulations are used to distinct between different wind driving mechanisms. The simulations were performed with the real surface topography at resolution of about 60 m. These simulations resolve the obstacle-induced turbulence and the turbulence in the non-stratified boundary layer core. The simulations suggest the leading roles of the thermal land-sea breeze circulation and the mechanical wind channeling in the modulation of the valley winds. The characteristic signatures of the developed down-slope gravity-accelerated flow, that is, the katabatic wind, were found to be of lesser significance under typical meteorological conditions in the valley.

  18. Biological Reclaiming of Recycled Rubber and Its Effect on Mechanical Properties of New Rubber Vulcanizates

    Directory of Open Access Journals (Sweden)

    Maryam Mansourirad

    2014-12-01

    Full Text Available Nowadays, due to environmental concerns, there has been great attention to recycling and reclaiming of tires. Different methods have been used for reclaiming or desulfurization of rubber. One of these methods, in which desulfurization of rubber happens with no damage to the polymer structure, is desulfurization by biological microorganisms. In this research the application and performance of thermophilic and sulfur oxidizing bacteria, Acidianus brierleyi for this purpose was investigated. Ground tire rubber was detoxified with organic solvents, and the optimum conditions for growing microorganisms in the existence of rubber powder in the shaker flasks were determined. In order to accelerate the process, the suitable conditions for growth of bacteria and desulfurization in the bioreactor were adopted. Fourier transfer infrared spectroscopy and scanning electron microscopy were employed to characterize desulfurization of bio-treated powder from bioreactor. The results indicated that morphological changes on powder surface and reduction of sulfur bonds have occurred. Samples from bioreactors, with and without bacteria and also untreated rubber powder were compounded with virgin styrene butadiene rubber. Tensile and dynamic properties were investigated using uni-direction tensile test and dynamic-mechanical-thermal analysis, respectively. Although some differences in dynamic-mechanical-thermal properties of samples pointed to stronger interaction between rubber matrix and treated rubber powder, no significant improvements in the mechanical properties of vulcanizates containing A.brierleyi-treated powder were observed. Low concentration of sulfur in rubber vulcanizates, chemical bonds of sulfur, and low efficiency of A. brierleyi in breaking sulfur bonds and reclaiming rubber were considered as the reasons for low efficiency of this treatment process.

  19. Dynamic processes of domain switching in lead zirconate titanate under cyclic mechanical loading by in situ neutron diffraction

    International Nuclear Information System (INIS)

    Pojprapai, Soodkhet; Luo, Zhenhua; Clausen, Bjorn; Vogel, Sven C.; Brown, Donald W.; Russel, Jennifer; Hoffman, Mark

    2010-01-01

    The performance of ferroelectric ceramics is governed by the ability of domains to switch. A decrease in the switching ability can lead to degradation of the materials and failure of ferroelectric devices. In this work the dynamic properties of domain reorientation are studied. In situ time-of-flight neutron diffraction is used to probe the evolution of ferroelastic domain texture under mechanical cyclic loading in bulk lead zirconate titanate ceramics. The high sensitivity of neutron diffraction to lattice strain is exploited to precisely analyze the change of domain texture and strain through a full-pattern Rietveld method. These results are then used to construct a viscoelastic model, which explains the correlation between macroscopic phenomena (i.e. creep and recovered deformation) and microscopic dynamic behavior (i.e. ferroelastic switching, lattice strain).

  20. Unravel lipid accumulation mechanism in oleaginous yeast through single cell systems biology study

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shiyou; Xiaoliang, Xie

    2017-12-18

    Replacement of petroleum with advanced biofuels is critical for environmental protection needs, sustainable and secure energy demands, and economic development. Bacteria, yeasts, and fungi can naturally synthesize fatty acids, isoprenoids, or polyalkanoates for energy storage, and therefore are currently explored for hydrocarbon fuel production. Oleaginous yeasts can accumulate high levels of lipids in the form of triacylglycerols (TAGs) when encountering stress conditions or imbalanced growth (e.g., growing under excess carbon sources and limited nitrogen conditions). Advantages of using oleaginous yeast as cell factories include short duplication time (< 1 hour), high yield of intracellular droplets, and easy scale-up for industrial production. Currently, various oleaginous yeasts (e.g., Yarrowia, Candida, Rhodotorulla, Rhodosporidium, Cryptococcus, Trichosporon, and Lipomyces) have been developed as potential advanced biofuel producers. Oleaginous yeast lipid production has two phases: 1) growth phase, where cells utilize the carbon and nitrogen source to build up biomass. And 2) lipid accumulation phase, where they convert carbon source in media into the storage lipid body. (i.e. a high carbon to nitrogen ratio leads to high lipid production). The lipid production varies dramatically when different sugar, e.g. glucose, xylose is used as carbon source. The efficient utilization of all monomeric sugars of hexoses and pentoses from various lignocellulosic biomass processing approaches is the key for economic lignocellulosic biofuel production. In this project, we explored lipid production in oleaginous yeast under different nitrogen and sugar conditions at the single-cell level. To understand the lipid production mechanism and identify genetic features responsive to lipid accumulation in the presence of pentose and nitrogen, we developed an automated chemical imaging and single-cell transcriptomics method to correlate the lipid accumulation with the

  1. Radiation-induced DNA-protein cross-links: Mechanisms and biological significance.

    Science.gov (United States)

    Nakano, Toshiaki; Xu, Xu; Salem, Amir M H; Shoulkamy, Mahmoud I; Ide, Hiroshi

    2017-06-01

    Ionizing radiation produces various DNA lesions such as base damage, DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and DNA-protein cross-links (DPCs). Of these, the biological significance of DPCs remains elusive. In this article, we focus on radiation-induced DPCs and review the current understanding of their induction, properties, repair, and biological consequences. When cells are irradiated, the formation of base damage, SSBs, and DSBs are promoted in the presence of oxygen. Conversely, that of DPCs is promoted in the absence of oxygen, suggesting their importance in hypoxic cells, such as those present in tumors. DNA and protein radicals generated by hydroxyl radicals (i.e., indirect effect) are responsible for DPC formation. In addition, DPCs can also be formed from guanine radical cations generated by the direct effect. Actin, histones, and other proteins have been identified as cross-linked proteins. Also, covalent linkages between DNA and protein constituents such as thymine-lysine and guanine-lysine have been identified and their structures are proposed. In irradiated cells and tissues, DPCs are repaired in a biphasic manner, consisting of fast and slow components. The half-time for the fast component is 20min-2h and that for the slow component is 2-70h. Notably, radiation-induced DPCs are repaired more slowly than DSBs. Homologous recombination plays a pivotal role in the repair of radiation-induced DPCs as well as DSBs. Recently, a novel mechanism of DPC repair mediated by a DPC protease was reported, wherein the resulting DNA-peptide cross-links were bypassed by translesion synthesis. The replication and transcription of DPC-bearing reporter plasmids are inhibited in cells, suggesting that DPCs are potentially lethal lesions. However, whether DPCs are mutagenic and induce gross chromosomal alterations remains to be determined. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Virtual Agonist-antagonist Mechanisms Produce Biological Muscle-like Functions: An Application for Robot Joint Control

    DEFF Research Database (Denmark)

    Xiong, Xiaofeng; Wörgötter, Florentin; Manoonpong, Poramate

    2014-01-01

    Purpose – Biological muscles of animals have a surprising variety of functions, i.e., struts, springs, and brakes. According to this, the purpose of this paper is to apply virtual agonist-antagonist mechanisms to robot joint control allowing for muscle-like functions and variably compliant joint......, variably compliant joint motions can be produced without mechanically bulky and complex mechanisms or complex force/toque sensing at each joint. Moreover, through tuning the damping coefficient of the VAAM, the functions of the VAAM are comparable to biological muscles. Originality/value – The model (i.......e., VAAM) provides a way forward to emulate muscle-like functions that are comparable to those found in physiological experiments of biological muscles. Based on these muscle-like functions, the robotic joints can easily achieve variable compliance that does not require complex physical components...

  3. Improvement of fatigue resistance for multilayer lead zirconate titanate (PZT)-based ceramic actuators by external mechanical loads

    Science.gov (United States)

    Yang, Gang; Yue, Zhenxing; Ji, Ye; Chu, Xiangcheng; Li, Longtu

    2008-12-01

    The influence of external compressive loads, applied along a direction perpendicular to polarization, on fatigue behaviors of multilayer lead zirconate titanate (PZT)-based ceramic actuators was investigated. Under no external mechanical load, a normal fatigue behavior was observed, demonstrating that both switching polarization (Pswitching) and remnant polarization (Pr) progressively decreased with increasing switching cycles due to domain pinning by charge point defects. However, an anomalous enhancement in both switching and remnant polarizations was observed upon application of the external compressive loads. After 5×106 cycles of polarization switching, Pswitching and Pr increase by about 13% and 6% at 40 MPa, respectively, while Pswitching and Pr increase by about 11% and 21% at 60 MPa, respectively. The improvement of fatigue resistance can be attributed to non-180° domain switching and suppression of microcracking, triggered by external mechanical loads.

  4. [Mechanism of action of intravesical BCG. Biological bases and clinical applicability.

    Science.gov (United States)

    Carballido, Joaquín A; Rodríguez Monsalve, María

    2018-05-01

    the lytic cytotoxic antitumor response, and its integration in the current intravesical treatment regimens The implication of all these mechanisms in the varied capacity of clinical response observed in patients, reviewing the current status of knowledge of BCG mechanisms of action, leads unavoidably to the search of better clinical efficacy through eventual immune response markers and to set the approach to the knowledge of the individual reactivity of the immune system of each patient as a determinant factor to be able to adopt adjusted therapeutic patterns.

  5. Performance of a modified multi-stage bubble column reactor for lead(II) and biological oxygen demand removal from wastewater using activated rice husk

    International Nuclear Information System (INIS)

    Sahu, J.N.; Agarwal, S.; Meikap, B.C.; Biswas, M.N.

    2009-01-01

    The excessive release of wastewater into the environment is a major concern worldwide. Adsorption is the one of the most effective technique for treatment of wastewater. In this work activated carbon prepared from rice husk has been used as an adsorbent. In the present investigation a three phase modified multi-stage bubble column reactor (MMBCR) has been designed to remove lead and biochemical oxygen demand (BOD) from wastewater by means of its adsorption onto the surface of activated rice husk. The multi-staging has been achieved by hydrodynamically induced continuous bubble generation, breakup and regeneration. Under optimum conditions, maximum lead and BOD reduction achieved using activated rice husk was 77.15% and 19.05%, respectively. Results showed MMBCR offered appreciated potential benefits for lead removal from wastewater and BOD removal, even this extent of removal is encouraging and the MMBCR can be used a pretreatment unit before subjecting the wastewater to biological treatment

  6. Performance of a modified multi-stage bubble column reactor for lead(II) and biological oxygen demand removal from wastewater using activated rice husk.

    Science.gov (United States)

    Sahu, J N; Agarwal, S; Meikap, B C; Biswas, M N

    2009-01-15

    The excessive release of wastewater into the environment is a major concern worldwide. Adsorption is the one of the most effective technique for treatment of wastewater. In this work activated carbon prepared from rice husk has been used as an adsorbent. In the present investigation a three phase modified multi-stage bubble column reactor (MMBCR) has been designed to remove lead and biochemical oxygen demand (BOD) from wastewater by means of its adsorption onto the surface of activated rice husk. The multi-staging has been achieved by hydrodynamically induced continuous bubble generation, breakup and regeneration. Under optimum conditions, maximum lead and BOD reduction achieved using activated rice husk was 77.15% and 19.05%, respectively. Results showed MMBCR offered appreciated potential benefits for lead removal from wastewater and BOD removal, even this extent of removal is encouraging and the MMBCR can be used a pretreatment unit before subjecting the wastewater to biological treatment.

  7. Mechanism of the biological response to winter cooling in the northeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.; PrasannaKumar, S.; Bhattathiri, P.M.A.; DileepKumar, M.; Raghukumar, S.; Nair, K.K.C.; Ramaiah, N.

    The Arabian Sea is one of the most biologically productive ocean regions, mainly due to the upwelling of nutrients during the summer (southwest) monsoon. But the northern Arabian Sea continues to sustain fairly high biological production after...

  8. Activation of chemical biological defense mechanisms and remission of vital oxidative injury by low dose radiation

    International Nuclear Information System (INIS)

    Yamaoka, K.; Nomura, T.; Kojima, S.

    2000-01-01

    Excessive active oxygen produced in vivo by various causes is toxic. Accumulation of oxidation injuries due to excessive active causes cell and tissue injuries, inducing various pathologic conditions such as aging and carcinogenesis. On the other hand, there are chemical defense mechanisms in the body that eliminate active oxygen or repair damaged molecules, defending against resultant injury. It is interesting reports that appropriate oxidation stress activate the chemical biological defense mechanisms. In this study, to elucidate these phenomena and its mechanism by low dose radiation, we studied on the below subjects. Activation of chemical biological defense mechanisms by low dose radiation: (1) The effects radiation on lipid peroxide (LPO) levels in the organs, membrane fluidity and the superoxide dismutase (SOD) activity were examined in rats and rabbits. Rats were irradiated with low dose X-ray over their entire bodies, and rabbits inhaled vaporized radon spring water, which primarily emitted α-ray. The following results were obtained. Unlike high dose X-ray, low dose X-ray and radon inhalation both reduced LPO levels and made the state of the SH-group on membrane-bound proteins closer to that of juvenile animals, although the sensitivity to radioactivity varied depending on the age of the animals and among different organs and tissues. The SOD activity was elevated, suggesting that low dose X-ray and radon both activate the host defensive function. Those changes were particularly marked in the organs related to immune functions of the animals which received low dose X-ray, while they were particularly marked in the brain after radon inhalation. It was also found that those changes continued for longer periods after low dose X-irradiation. (2) Since SOD is an enzyme that mediates the dismutation of O 2 - to H 2 O 2 , the question as to whether the resultant H 2 O 2 is further detoxicated into H 2 O and O 2 or not must still be evaluated. Hence, we studied

  9. Evaluation of feed COD/sulfate ratio as a control criterion for the biological hydrogen sulfide production and lead precipitation

    International Nuclear Information System (INIS)

    Velasco, Antonio; Ramirez, Martha; Volke-Sepulveda, Tania; Gonzalez-Sanchez, Armando; Revah, Sergio

    2008-01-01

    The ability of sulfate-reducing bacteria to produce hydrogen sulfide and the high affinity of sulfide to react with divalent metallic cations represent an excellent option to remove heavy metals from wastewater. Different parameters have been proposed to control the hydrogen sulfide production by anaerobic bacteria, such as the organic and sulfate loading rates and the feed COD/SO 4 2- ratio. This work relates the feed COD/SO 4 2- ratio with the hydrogen sulfide production and dissolved lead precipitation, using ethanol as carbon and energy source in an up-flow anaerobic sludge blanket reactor. A maximum dissolved sulfide concentration of 470 ± 7 mg S/L was obtained at a feed COD/SO 4 2- ratio of 2.5, with sulfate and ethanol conversions of approximately 94 and 87%, respectively. The lowest dissolved sulfide concentration (145 ± 10 mg S/L) was observed with a feed COD/SO 4 2- ratio of 0.67. Substantial amounts of acetate (510-1730 mg/L) were produced and accumulated in the bioreactor from ethanol oxidation. Although only incomplete oxidation of ethanol to acetate was observed, the consortium was able to remove 99% of the dissolved lead (200 mg/L) with a feed COD/SO 4 2- ratio of 1.5. It was found that the feed COD/SO 4 2- ratio could be an adequate parameter to control the hydrogen sulfide production and the consequent precipitation of dissolved lead

  10. Mechanical-biological waste treatment and the associated occupational hygiene in Finland

    International Nuclear Information System (INIS)

    Tolvanen, Outi K.; Haenninen, Kari I.

    2006-01-01

    A special feature of waste management in Finland has been the emphasis on the source separation of kitchen biowaste (catering waste); more than two-thirds of the Finnish population participates in this separation. Source-separated biowaste is usually treated by composting. The biowaste of about 5% of the population is handled by mechanical-biological treatment. A waste treatment plant at Mustasaari is the only plant in Finland using digestion for kitchen biowaste. For the protection of their employees, the plant owners commissioned a study on environmental factors and occupational hygiene in the plant area. During 1998-2000 the concentrations of dust, microbes and endotoxins and noise levels were investigated to identify possible problems at the plant. Three different work areas were investigated: the pre-processing and crushing hall, the bioreactor hall and the drying hall. Employees were asked about work-related health problems. Some problems with occupational hygiene were identified: concentrations of microbes and endotoxins may increase to levels harmful to health during waste crushing and in the bioreactor hall. Because employees complained of symptoms such as dry cough and rash or itching appearing once or twice a month, it is advisable to use respirator masks (class P3) during dusty working phases. The noise level in the drying hall exceeded the Finnish threshold value of 85 dBA. Qualitatively harmful factors for the health of employees are similar in all closed waste treatment plants in Finland. Quantitatively, however, the situation at the Mustasaari treatment plant is better than at some Finnish dry waste treatment plants. Therefore is reasonable to conclude that mechanical sorting, which produces a dry waste fraction for combustion and a biowaste fraction for anaerobic treatment, is in terms of occupational hygiene better for employees than combined aerobic treatment and dry waste treatment

  11. Formation of organizational and economic mechanism of rational use of aquatic biological resources

    Directory of Open Access Journals (Sweden)

    Stolbov A. G.

    2017-09-01

    Full Text Available The state of fisheries has been researched based on a systematic approach and comprehensive analysis of statistical data, the following issues have been characterized: the catch of aquatic biological resources (ABR, consumption of fish products, problems in the development of the fishing industry (fleet aging, lack of innovative technologies, the proliferation of IUU fishing4 , the high level of retail prices for fish, low degree of processing export products, overshoot "improper objects" of fishing, the gap in aquaculture development, low economic efficiency. To improve the quality of fishery management it has been proposed to form the organizational and economic mechanism of ABR rational use, which should include effective tools for the implementation of management decisions. Instead of the so-called "historical" principle it has been suggested to use the investment principle of quota allocation and rental payments. The basis for management of fishing industry should be scientifically based on the bioeconomic concept of ABR rational use, the essence of which is to preserve the ABR and at the same time to obtain the maximum output of finished products with high added value. To form the organizational and economic mechanism it is necessary to develop a programme of innovative development of the fisheries sector, a calendar programme of upgrading of fishing fleet, wellreasoned differential rates of rent payments for the ABR use, scenarios and graphic organization of work of fishing vessels in specific fishing areas, to form regional financial and industrial clusters, to expand the authority of the Fisheries Agency, to improve corporate social responsibility of the fishing business communities. Modernization of management system for ABR rational use can significantly reduce environmental pollution, ensure the effective delivery of catch to shore, their high-quality processing and the needs of the population in fish products.

  12. Integrated structural biology to unravel molecular mechanisms of protein-RNA recognition.

    Science.gov (United States)

    Schlundt, Andreas; Tants, Jan-Niklas; Sattler, Michael

    2017-04-15

    Recent advances in RNA sequencing technologies have greatly expanded our knowledge of the RNA landscape in cells, often with spatiotemporal resolution. These techniques identified many new (often non-coding) RNA molecules. Large-scale studies have also discovered novel RNA binding proteins (RBPs), which exhibit single or multiple RNA binding domains (RBDs) for recognition of specific sequence or structured motifs in RNA. Starting from these large-scale approaches it is crucial to unravel the molecular principles of protein-RNA recognition in ribonucleoprotein complexes (RNPs) to understand the underlying mechanisms of gene regulation. Structural biology and biophysical studies at highest possible resolution are key to elucidate molecular mechanisms of RNA recognition by RBPs and how conformational dynamics, weak interactions and cooperative binding contribute to the formation of specific, context-dependent RNPs. While large compact RNPs can be well studied by X-ray crystallography and cryo-EM, analysis of dynamics and weak interaction necessitates the use of solution methods to capture these properties. Here, we illustrate methods to study the structure and conformational dynamics of protein-RNA complexes in solution starting from the identification of interaction partners in a given RNP. Biophysical and biochemical techniques support the characterization of a protein-RNA complex and identify regions relevant in structural analysis. Nuclear magnetic resonance (NMR) is a powerful tool to gain information on folding, stability and dynamics of RNAs and characterize RNPs in solution. It provides crucial information that is complementary to the static pictures derived from other techniques. NMR can be readily combined with other solution techniques, such as small angle X-ray and/or neutron scattering (SAXS/SANS), electron paramagnetic resonance (EPR), and Förster resonance energy transfer (FRET), which provide information about overall shapes, internal domain

  13. A case of hypoglycemiainduced QT prolongation leading to torsade de pointes and a review of pathophysiological mechanisms

    Directory of Open Access Journals (Sweden)

    Faris Hannoodi

    2017-06-01

    Full Text Available Torsades de pointes is a life-threatening cardiac arrhythmia. Occurrence of this arrhythmia as a result of hypoglycemia has not been reported in the literature. We describe an interesting case of an insulindependent diabetic patient presenting with torsades de pointes resulting from hypoglycemia. A 62-year-old male was admitted to the hospital following an episode of severe insulin-induced hypoglycemia and a cardiac arrest. He was found to unresponsive at home after taking insulin. His serum glucose was found to be 18. He was given juice initially to normalize his glucose and was then transferred by EMS to ER where he was given 5% dextrose infusion. Analysis of the LifeVest rhythm recording showed torsades de pointes that was terminated by defibrillation of the LifeVest. Several mechanisms are responsible for torsade, including QT interval prolongation, adrenalin secretion and calcium overload leading to intracellular calcium oscillations. These mechanisms are a trigger to torsade de pointes. Predisposing factors were present leading torsade to occur.

  14. Robustness leads close to the edge of chaos in coupled map networks: toward the understanding of biological networks

    International Nuclear Information System (INIS)

    Saito, Nen; Kikuchi, Macoto

    2013-01-01

    Dynamics in biological networks are, in general, robust against several perturbations. We investigate a coupled map network as a model motivated by gene regulatory networks and design systems that are robust against phenotypic perturbations (perturbations in dynamics), as well as systems that are robust against mutation (perturbations in network structure). To achieve such a design, we apply a multicanonical Monte Carlo method. Analysis based on the maximum Lyapunov exponent and parameter sensitivity shows that systems with marginal stability, which are regarded as systems at the edge of chaos, emerge when robustness against network perturbations is required. This emergence of the edge of chaos is a self-organization phenomenon and does not need a fine tuning of parameters. (paper)

  15. The Spliced Leader Trans-Splicing Mechanism in Different Organisms: Molecular Details and Possible Biological Roles

    Directory of Open Access Journals (Sweden)

    Mainá eBitar

    2013-10-01

    Full Text Available The spliced leader (SL is a gene that generates a functional ncRNA that is composed of two regions: an intronic region of unknown function (SLi and an exonic region (SLe, which is transferred to the 5’ end of independent transcripts yielding mature mRNAs, in a process known as spliced leader trans-splicing (SLTS. The best described function for SLTS is to solve polycistronic transcripts into monocistronic units, specifically in Trypanosomatids. In other metazoans, it is speculated that the SLe addition could lead to increased mRNA stability, differential recruitment of the translational machinery, modification of the 5' region or a combination of these effects. Although important aspects of this mechanism have been revealed, several features remain to be elucidated. We have analyzed 157 SLe sequences from 148 species from 7 phyla and found a high degree of conservation among the sequences of species from the same phylum, although no considerable similarity seems to exist between sequences of species from different phyla. When analyzing case studies, we found evidence that a given SLe will always be related to a given set of transcripts in different species from the same phylum, and therefore, different SLe sequences from the same species would regulate different sets of transcripts. In addition, we have observed distinct transcript categories to be preferential targets for the SLe addition in different phyla. This work sheds light into crucial and controversial aspects of the SLTS mechanism. It represents a comprehensive study concerning various species and different characteristics of this important post-transcriptional regulatory mechanism.

  16. Investigation of reaction mechanisms during electroreduction of carbon dioxide on lead electrode for the production of organic compounds

    International Nuclear Information System (INIS)

    Innocent, B.

    2008-09-01

    The aim of this work was to promote the reduction of CO 2 through its electrochemical conversion (electro-synthesis) on a lead electrode into high added value products. Depending on the nature of electrolyte, the electro-reduction of carbon dioxide leads to different products. Various electrolytes (aqueous or organic, protic or aprotic) were used to study two mechanisms: hydrogenation (formation of formate) and electro-dimerization (synthesis of oxalate). Cyclic voltammetry studies have been carried out for electrochemically characterizing CO 2 reduction on Pb. The electrochemical investigation of the electrode electrolyte interface has shown that the process of CO 2 electro-reduction is a mass transfer control both in the organic and aqueous media. Electrochemical experiments (cyclic voltammetry, chrono-amperometry) coupled with in situ infrared reflectance spectroscopic techniques (SPAIRS, SNIFTIRS) have also shown that in aqueous medium (7 ≤pH≤9) hydrogeno-carbonate ions were reduced to formate. The modification of solvent (propylene carbonate) leads selectively to oxalate as the main reaction product. Long-term electrolyses were performed in a filter-press cell to deal large volumes. In aqueous medium, the reduction of HCO 3 - to HCOO - (R F = 89% at -2.5 mA cm -2 and 4 C) is always accompanied by the production of H 2 . (author)

  17. Carbon source recovery from excess sludge by mechanical disintegration for biological denitrification.

    Science.gov (United States)

    Zubrowska-Sudol, M

    2018-04-01

    The goal of the study was to evaluate the possibility of carbon source recovery from excess sludge by mechanical disintegration for biological denitrification. The total efficiency of denitrification, unit demand for organic compounds for denitrification, unit volume of disintegrated sludge and unit cost of nitrogen removal as a function of energy density used for excess sludge disintegration (70, 140 and 210 kJ/L) were analyzed. In the study a full-scale disc disintegrator was used (motor power: 30 kWh, motor speed: 2,950 rpm). It was shown that the amounts of organic compounds released from the activated sludge flocs at all tested levels of energy density are high enough to be used to intensify the removal of nitrogen compounds from wastewater. It was also documented that the energy density provided during process of disintegration was an important factor determining the characteristics of organic compounds obtained under the disintegration for their use in order to intensify the process of denitrification. The highest value of total efficiency of denitrification (50.5 ± 3.1 mg N/L) was obtained for carbon source recovery from excess sludge at 70 kJ/L, but the lowest unit cost of nitrogen removal occurred for 140 kJ/L (0.0019 ± 0.0011 EUR/g N).

  18. Reactivity of inorganic nanoparticles in biological environments: insights into nanotoxicity mechanisms

    International Nuclear Information System (INIS)

    Casals, E; Gonzalez, E; Puntes, V F

    2012-01-01

    A deeper understanding of the behaviour of inorganic nanoparticles in biological media is needed not only to fully control and develop the potential of these materials but also to increase knowledge of the physical chemistry of inorganic materials when their morphology approaches that of molecular entities. Although this knowledge and control is not yet entirely acquired, industry and society are already using nanomaterials in greater quantities and in consumer products. As normally happens when something new arrives in society, the interest in the broader implications of this emerging technology has grown together with unfounded ‘nanoeuphoria’ and ‘nanoscares’. In this context, only by understanding the mechanisms of the nano-bio interaction will it be possible to safely develop nanotechnology. In this review, we discuss on how nanoparticles behave once they are naturally or intentionally produced and are exposed to humans and the environment. The response of nanoparticles inside organisms or released to the environment is complex and diverse, and depends on a variety of parameters involved. Mainly, they may (i) be aggregated into microscopic particles or embedded in exposed materials; (ii) the surfaces of the nanoparticles, which determine their bioactivity, experience constant modifications; and (iii) nanoparticles may corrode and dissolve or they can suffer morphological modifications.

  19. Stress biology and aging mechanisms: toward understanding the deep connection between adaptation to stress and longevity.

    Science.gov (United States)

    Epel, Elissa S; Lithgow, Gordon J

    2014-06-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress ("hormetic stress"). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses ("toxic stress") and shorten lifespan. One key question is whether the stressors that are well understood in basic models of aging can help us understand psychological stressors and human health. The psychological stress response promotes regulatory changes important in aging (e.g., increases in stress hormones, inflammation, oxidative stress, insulin). The negative effects of severe stress are well documented in humans. Potential positive effects of acute stress (stress resistance) are less studied, especially at the cellular level. Can stress resistance slow the rate of aging in humans, as it does in model organisms? If so, how can we promote stress resistance in humans? We urge a new research agenda embracing the continuum from cellular stress to psychological stress, using basic and human research in tandem. This will require interdisciplinary novel approaches that hold much promise for understanding and intervening in human chronic disease. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Reactivity of inorganic nanoparticles in biological environments: insights into nanotoxicity mechanisms

    Science.gov (United States)

    Casals, E.; Gonzalez, E.; Puntes, V. F.

    2012-11-01

    A deeper understanding of the behaviour of inorganic nanoparticles in biological media is needed not only to fully control and develop the potential of these materials but also to increase knowledge of the physical chemistry of inorganic materials when their morphology approaches that of molecular entities. Although this knowledge and control is not yet entirely acquired, industry and society are already using nanomaterials in greater quantities and in consumer products. As normally happens when something new arrives in society, the interest in the broader implications of this emerging technology has grown together with unfounded ‘nanoeuphoria’ and ‘nanoscares’. In this context, only by understanding the mechanisms of the nano-bio interaction will it be possible to safely develop nanotechnology. In this review, we discuss on how nanoparticles behave once they are naturally or intentionally produced and are exposed to humans and the environment. The response of nanoparticles inside organisms or released to the environment is complex and diverse, and depends on a variety of parameters involved. Mainly, they may (i) be aggregated into microscopic particles or embedded in exposed materials; (ii) the surfaces of the nanoparticles, which determine their bioactivity, experience constant modifications; and (iii) nanoparticles may corrode and dissolve or they can suffer morphological modifications.

  1. Water regime of mechanical-biological pretreated waste materials under fast-growing trees.

    Science.gov (United States)

    Rüth, Björn; Lennartz, Bernd; Kahle, Petra

    2007-10-01

    In this study mechanical-biological pre-treated waste material (MBP) was tested for suitability to serve as an alternative surface layer in combination with fast-growing and water-consumptive trees for final covers at landfill sites. The aim was to quantify evapotranspiration and seepage losses by numerical model simulations for two sites in Germany. In addition, the leaf area index (LAI) of six tree species over the growing season as the driving parameter for transpiration calculations was determined experimentally. The maximum LAI varied between 3.8 and 6.1 m2 m(-2) for poplar and willow clones, respectively. The evapotranspiration calculations revealed that the use of MBP waste material for re-cultivation enhanced evapotranspiration by 40 mm year(-1) (10%) over an 11 year calculation period compared to a standard mineral soil. Between 82% (for LAI(max) = 3.8) and 87% (for LAI(max) = 6.1) of the average annual precipitation (506 mm) could be retained from the surface layer assuming eastern German climate conditions, compared with a retention efficiency between 79 and 82% for a mineral soil. Although a MBP layer in conjunction with water-consumptive trees can reduce vertical water losses as compared to mineral substrates, the effect is not sufficient to meet legal regulations.

  2. Constraints on Biological Mechanism from Disease Comorbidity Using Electronic Medical Records and Database of Genetic Variants.

    Directory of Open Access Journals (Sweden)

    Steven C Bagley

    2016-04-01

    Full Text Available Patterns of disease co-occurrence that deviate from statistical independence may represent important constraints on biological mechanism, which sometimes can be explained by shared genetics. In this work we study the relationship between disease co-occurrence and commonly shared genetic architecture of disease. Records of pairs of diseases were combined from two different electronic medical systems (Columbia, Stanford, and compared to a large database of published disease-associated genetic variants (VARIMED; data on 35 disorders were available across all three sources, which include medical records for over 1.2 million patients and variants from over 17,000 publications. Based on the sources in which they appeared, disease pairs were categorized as having predominant clinical, genetic, or both kinds of manifestations. Confounding effects of age on disease incidence were controlled for by only comparing diseases when they fall in the same cluster of similarly shaped incidence patterns. We find that disease pairs that are overrepresented in both electronic medical record systems and in VARIMED come from two main disease classes, autoimmune and neuropsychiatric. We furthermore identify specific genes that are shared within these disease groups.

  3. Quinoxaline 1, 4-di-N-oxides: Biological activities and mechanisms of actions

    Directory of Open Access Journals (Sweden)

    Guyue eCheng

    2016-03-01

    Full Text Available Quinoxaline 1, 4-di-N-oxides (QdNOs have manifold biological properties, including antimicrobial, antitumoral, antitrypanosomal and antiinflammatory/antioxidant activities. These diverse activities endow them broad applications and prospects in human and veterinary medicines. As QdNOs arouse widespread interest, the evaluation of their medicinal chemistry is still in progress. In the meantime, adverse effects have been reported in some of the QdNO derivatives. For example, genotoxicity and bacterial resistance have been found in QdNO antibacterial growth promoters, conferring urgent need for discovery of new QdNO drugs. However, the modes of actions of QdNOs are not fully understood, hindering the development and innovation of these promising compounds. Here, QdNOs are categorized based on the activities and usages, among which the antimicrobial activities are consist of antibacterial, antimycobacterial and anticandida activities, and the antiprotozoal activities include antitrypanosomal, antimalarial, antitrichomonas and antiamoebic activities. The structure-activity relationship and the mode of actions of each type of activity of QdNOs are summarized, and the toxicity and the underlying mechanisms are also discussed, providing insight for the future research and development of these fascinating compounds.

  4. Physical Activity and Gastrointestinal Cancers: Primary and Tertiary Preventive Effects and Possible Biological Mechanisms

    Directory of Open Access Journals (Sweden)

    Karen Steindorf

    2015-07-01

    Full Text Available Gastrointestinal cancers account for 37% of all cancer deaths worldwide, underlining the need to further investigate modifiable factors for gastrointestinal cancer risk and prognosis. This review summarizes the corresponding evidence for physical activity (PA, including, briefly, possible biological mechanisms. Despite high public health relevance, there is still a scarcity of studies, especially for tertiary prevention. Besides the convincing evidence of beneficial effects of PA on colon cancer risk, clear risk reduction for gastroesophageal cancer was identified, as well as weak indications for pancreatic cancer. Inverse associations were observed for liver cancer, yet based on few studies. Only for rectal cancer, PA appeared to be not associated with cancer risk. With regard to cancer-specific mortality of the general population, published data were rare but indicated suggestive evidence of protective effects for colon and liver cancer, and to a lesser extent for rectal and gastroesophageal cancer. Studies in cancer patients on cancer-specific and total mortality were published for colorectal cancer only, providing good evidence of inverse associations with post-diagnosis PA. Overall, evidence of associations of PA with gastrointestinal cancer risk and progression is promising but still limited. However, the already available knowledge further underlines the importance of PA to combat cancer.

  5. Evaluation of feed COD/sulfate ratio as a control criterion for the biological hydrogen sulfide production and lead precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Velasco, Antonio [Direccion General del Centro Nacional de Investigacion y Capacitacion Ambiental-Instituto Nacional de Ecologia, Av. San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico)], E-mail: jvelasco@ine.gob.mx; Ramirez, Martha [Direccion General del Centro Nacional de Investigacion y Capacitacion Ambiental-Instituto Nacional de Ecologia, Av. San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Volke-Sepulveda, Tania [Departamento de Biotecnologia, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Gonzalez-Sanchez, Armando [Departamento de Ingenieria de Procesos, Universidad Autonoma Metropolitana-Iztapalapa, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Revah, Sergio [Departamento de Procesos y Tecnologia, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico)

    2008-03-01

    The ability of sulfate-reducing bacteria to produce hydrogen sulfide and the high affinity of sulfide to react with divalent metallic cations represent an excellent option to remove heavy metals from wastewater. Different parameters have been proposed to control the hydrogen sulfide production by anaerobic bacteria, such as the organic and sulfate loading rates and the feed COD/SO{sub 4}{sup 2-} ratio. This work relates the feed COD/SO{sub 4}{sup 2-} ratio with the hydrogen sulfide production and dissolved lead precipitation, using ethanol as carbon and energy source in an up-flow anaerobic sludge blanket reactor. A maximum dissolved sulfide concentration of 470 {+-} 7 mg S/L was obtained at a feed COD/SO{sub 4}{sup 2-} ratio of 2.5, with sulfate and ethanol conversions of approximately 94 and 87%, respectively. The lowest dissolved sulfide concentration (145 {+-} 10 mg S/L) was observed with a feed COD/SO{sub 4}{sup 2-} ratio of 0.67. Substantial amounts of acetate (510-1730 mg/L) were produced and accumulated in the bioreactor from ethanol oxidation. Although only incomplete oxidation of ethanol to acetate was observed, the consortium was able to remove 99% of the dissolved lead (200 mg/L) with a feed COD/SO{sub 4}{sup 2-} ratio of 1.5. It was found that the feed COD/SO{sub 4}{sup 2-} ratio could be an adequate parameter to control the hydrogen sulfide production and the consequent precipitation of dissolved lead.

  6. Mechanisms of virus immune evasion lead to development from chronic inflammation to cancer formation associated with human papillomavirus infection.

    Science.gov (United States)

    Senba, Masachika; Mori, Naoki

    2012-10-02

    Human papillomavirus (HPV) has developed strategies to escape eradication by innate and adaptive immunity. Immune response evasion has been considered an important aspect of HPV persistence, which is the main contributing factor leading to HPV-related cancers. HPV-induced cancers expressing viral oncogenes E6 and E7 are potentially recognized by the immune system. The major histocompatibility complex (MHC) class I molecules are patrolled by natural killer cells and CD8+ cytotoxic T lymphocytes, respectively. This system of recognition is a main target for the strategies of immune evasion deployed by viruses. The viral immune evasion proteins constitute useful tools to block defined stages of the MHC class I presentation pathway, and in this way HPV avoids the host immune response. The long latency period from initial infection to persistence signifies that HPV evolves mechanisms to escape the immune response. It has now been established that there are oncogenic mechanisms by which E7 binds to and degrades tumor suppressor Rb, while E6 binds to and inactivates tumor suppressor p53. Therefore, interaction of p53 and pRb proteins can give rise to an increased immortalization and genomic instability. Overexpression of NF-κB in cervical and penile cancers suggests that NF-κB activation is a key modulator in driving chronic inflammation to cancer. HPV oncogene-mediated suppression of NF-κB activity contributes to HPV escape from the immune system. This review focuses on the diverse mechanisms of the virus immune evasion with HPV that leads to chronic inflammation and cancer.

  7. Under the Skin: Using Theories From Biology and the Social Sciences to Explore the Mechanisms Behind the Black–White Health Gap

    Science.gov (United States)

    Darity, William A.

    2010-01-01

    Equity and social well-being considerations make Black–White health disparities an area of important concern. Although previous research suggests that discrimination- and poverty-related stressors play a role in African American health outcomes, the mechanisms are unclear. Allostatic load is a concept that can be employed to demonstrate how environmental stressors, including psychosocial ones, may lead to a cumulative physiological toll on the body. We discuss both the usefulness of this framework for understanding how discrimination can lead to worse health among African Americans, and the challenges for conceptualizing biological risk with existing data and methods. We also contrast allostatic load with theories of historical trauma such as posttraumatic slavery syndrome. Finally, we offer our suggestions for future interdisciplinary research on health disparities. PMID:20147678

  8. Formation of the vertical heterogeneity in the Lake Shira ecosystem: the biological mechanisms and the mathematical model

    NARCIS (Netherlands)

    Degermendzhy, A.G.; Belolipetsky, V.M.; Zotina, T.A.; Gulati, R.D.

    2002-01-01

    Data on the seasonal changes in vertical heterogeneity of the physical-chemical and biological parameters of the thermally stratified Shira Lake ecosystem (Khakasia, Siberia) in 1996–2000 have been analyzed. The interaction mechanisms involving: (1) The plankton populations in aerobic and anaerobic

  9. Earth mechanisms (fluid and solid), life mechanisms and stable isotope tracers. Isotopes and biology, a great project

    International Nuclear Information System (INIS)

    Fromageot, P.

    1997-01-01

    Historical and recent review of the development and use of radioactive isotopes for biological studies in France: study of the intermediate metabolism with 14 C tracers in organic molecules; study and biosynthesis of macromolecules (DNA, RNA and polynucleotides) through the use of marked nucleotides; tracer proteins for use in NMR and protein engineering, use of tritium for the study of hormonal regulation

  10. Molecular mechanisms of the epithelial transport of toxic metal ions, particularly mercury, cadmium, lead, arsenic, zinc and copper. Progress report, January 1, 1980-December 31, 1980

    International Nuclear Information System (INIS)

    Wasserman, R.H.

    1980-01-01

    Investigations were continued to elucidate the mode of transepithelial transport of toxic metal ions across the gastrointestinal tract, as well as their interactions with biological processes and other metal ions. All experimental details that are either published, submitted for publication or in press during this report period are included in the Appendix. Primary attention for this report has been given to the intestinal absorption of lead and its interaction with other biological moieties

  11. Space radiation-induced bystander effect: kinetics of biologic responses, mechanisms, and significance of secondary radiations

    International Nuclear Information System (INIS)

    Gonon, Geraldine

    2011-01-01

    Widespread evidence indicates that exposure of cell cultures to a particles results in significant biological changes in both the irradiated and non-irradiated bystander cells in the population. The induction of non-targeted biological responses in cell cultures exposed to low fluences of high charge (Z) and high energy (E) particles is relevant to estimates of the health risks of space radiation and to radiotherapy. Here, we investigated the mechanisms underlying the induction of stressful effects in confluent normal human fibroblast cultures exposed to low fluences of 1000 MeV/u iron ions (linear energy transfer (LET) 151 keV/μm), 600 MeV/u silicon ions (LET 50 keV/μm) or 290 MeV/u carbon ions (LET 13 keV/μm). We compared the results with those obtained in cell cultures exposed, in parallel, to low fluences of 0.92 MeV/u a particles (LET 109 keV/μm). Induction of DNA damage, changes in gene expression, protein carbonylation and lipid peroxidation during 24 h after exposure of confluent cultures to mean doses as low as 0.2 cGy of iron or silicon ions strongly supported the propagation of stressful effects from irradiated to bystander cells. At a mean dose of 0.2 cGy, only 1 and 3 % of the cells would be targeted through the nucleus by an iron or silicon ion, respectively. Within 24 h post-irradiation, immunoblot analyses revealed significant increases in the levels of phospho-TP53 (serine 15), p21Waf1 (also known as CDKN1A), HDM2, phospho-ERK1/2, protein carbonylation and lipid peroxidation. The magnitude of the responses suggested participation of non-targeted cells in the response. Furthermore, when the irradiated cell populations were subcultured in fresh medium shortly after irradiation, greater than expected increases in the levels of these markers were also observed during 24 h. Together, the results imply a rapidly propagated and persistent bystander effect. In situ analyses in confluent cultures showed 53BP1 foci formation, a marker of DNA damage, in

  12. Clinical indications and biological mechanisms of splenic irradiation in autoimmune diseases

    International Nuclear Information System (INIS)

    Weinmann, M.; Becker, G.; Einsele, H.; Bamberg, M.

    2001-01-01

    Background: Splenic irradiation (SI) is a fairly unknown treatment modality in autoimmune disorders like autoimmune thrombocytopenia (AIT) or autoimmune hemolytic anemia (AIHA), which may provide an effective, low toxic and cost-effective treatment for selected patients. Patients, Materials and Methods: This article reviews the limited experiences on splenic irradiation in autoimmune thrombocytopenia by analyzing the current studies including 71 patients and some preliminary reports on splenic irradiation in autoimmune hemolytic anemia. Results: In autoimmune thrombocytopenia between 40 and 90% of all patients responded, but most of them relapsed within 4 to 6 months after splenic irradiation. Between 10 and 20% of all patients had a sustained response. The efficacy of splenic irradiation in HIV-associated cases of thrombocytopenia is probably lower than in other forms of autoimmune thrombocytopenia, but especially in this group immunosuppressive drug treatment of autoimmune thrombocytopenia exposes some problems. In autoimmune hemolytic anemia there are some case reports about efficacy of splenic irradiation. Toxicity of splenic irradiation in both diseases was very moderate. Conclusions: For HIV patients, for elderly patients or patients at high risk for complications following splenectomy splenic irradiation might be a treatment option. Splenic irradiation as preoperative treatment in patients not responding to or not suitable for immunosuppressive drugs prior to splenectomy may be a promising new application of splenic irradiation to reduce adverse effects of splenectomy in thrombocytopenic patients. A further analysis of the biological mechanisms underlying splenic irradiation may help to improve patient selection, to optimize dose concepts and treatment schedules and will improve understanding of radiotherapy as an immunomodulatory treatment modality. (orig.) [de

  13. An integrated chemical biology approach reveals the mechanism of action of HIV replication inhibitors.

    Science.gov (United States)

    Pagano, Nicholas; Teriete, Peter; Mattmann, Margrith E; Yang, Li; Snyder, Beth A; Cai, Zhaohui; Heil, Marintha L; Cosford, Nicholas D P

    2017-12-01

    Continuous flow (microfluidic) chemistry was employed to prepare a small focused library of dihydropyrimidinone (DHPM) derivatives. Compounds in this class have been reported to exhibit activity against the human immunodeficiency virus (HIV), but their molecular target had not been identified. We tested the initial set of DHPMs in phenotypic assays providing a hit (1i) that inhibited the replication of the human immunodeficiency virus HIV in cells. Flow chemistry-driven optimization of 1i led to the identification of HIV replication inhibitors such as 1l with cellular potency comparable with the clinical drug nevirapine (NVP). Mechanism of action (MOA) studies using cellular and biochemical assays coupled with 3D fingerprinting and in silico modeling demonstrated that these drug-like probe compounds exert their effects by inhibiting the viral reverse transcriptase polymerase (RT). This led to the design and synthesis of the novel DHPM 1at that inhibits the replication of drug resistant strains of HIV. Our work demonstrates that combining flow chemistry-driven analogue refinement with phenotypic assays, in silico modeling and MOA studies is a highly effective strategy for hit-to-lead optimization applicable to the discovery of future therapeutic agents. Copyright © 2017. Published by Elsevier Ltd.

  14. Radiochemistry - Applications in the study of radical mechanisms of biological interest

    International Nuclear Information System (INIS)

    Foos, Jacques

    1982-01-01

    In biology, oxygen reducing processes give rise to the formation of intermediate radicals. One of the major breakthroughs of radiation chemistry of aqueous solutions is the identification of these compounds. The author describes the techniques used to study the reaction of these radicals (of radiolytic origin) with biological molecules [fr

  15. Selective ionic liquid ferrofluid based dispersive-solid phase extraction for simultaneous preconcentration/separation of lead and cadmium in milk and biological samples.

    Science.gov (United States)

    Fasih Ramandi, Negin; Shemirani, Farzaneh

    2015-01-01

    For the first time, a selective ionic liquid ferrofluid has been used in dispersive solid phase extraction (IL-FF-D-SPE) for simultaneous preconcentration and separation of lead and cadmium in milk and biological samples combined with flame atomic absorption spectrometry. To improve the selectivity of the ionic liquid ferrofluid, the surface of TiO2 nanoparticles with a magnetic core as sorbent was modified by loading 1-(2-pyridylazo)-2-naphtol. Due to the rapid injection of an appropriate amount of ionic liquid ferrofluid into the aqueous sample by a syringe, extraction can be achieved within a few seconds. In addition, based on the attraction of the ionic liquid ferrofluid to a magnet, no centrifugation step is needed for phase separation. The experimental parameters of IL-FF-D-SPE were optimized using a Box-Behnken design (BBD) after a Plackett-Burman screening design. Under the optimum conditions, the relative standard deviations of 2.2% and 2.4% were obtained for lead and cadmium, respectively (n=7). The limit of detections were 1.21 µg L(-1) for Pb(II) and 0.21 µg L(-1) for Cd(II). The preconcentration factors were 250 for lead and 200 for cadmium and the maximum adsorption capacities of the sorbent were 11.18 and 9.34 mg g(-1) for lead and cadmium, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Antiprotozoan lead discovery by aligning dry and wet screening: prediction, synthesis, and biological assay of novel quinoxalinones.

    Science.gov (United States)

    Martins Alho, Miriam A; Marrero-Ponce, Yovani; Barigye, Stephen J; Meneses-Marcel, Alfredo; Machado Tugores, Yanetsy; Montero-Torres, Alina; Gómez-Barrio, Alicia; Nogal, Juan J; García-Sánchez, Rory N; Vega, María Celeste; Rolón, Miriam; Martínez-Fernández, Antonio R; Escario, José A; Pérez-Giménez, Facundo; Garcia-Domenech, Ramón; Rivera, Norma; Mondragón, Ricardo; Mondragón, Mónica; Ibarra-Velarde, Froylán; Lopez-Arencibia, Atteneri; Martín-Navarro, Carmen; Lorenzo-Morales, Jacob; Cabrera-Serra, Maria Gabriela; Piñero, Jose; Tytgat, Jan; Chicharro, Roberto; Arán, Vicente J

    2014-03-01

    which the individual QSAR outputs are the inputs of the aforementioned fusion approach. Finally, the fusion model was used for the identification of a novel generation of lead-like antiprotozoan compounds by using ligand-based virtual screening of 'available' small molecules (with synthetic feasibility) in our 'in-house' library. A new molecular subsystem (quinoxalinones) was then theoretically selected as a promising lead series, and its derivatives subsequently synthesized, structurally characterized, and experimentally assayed by using in vitro screening that took into consideration a battery of five parasite-based assays. The chemicals 11(12) and 16 are the most active (hits) against apicomplexa (sporozoa) and mastigophora (flagellata) subphylum parasites, respectively. Both compounds depicted good activity in every protozoan in vitro panel and they did not show unspecific cytotoxicity on the host cells. The described technical framework seems to be a promising QSAR-classifier tool for the molecular discovery and development of novel classes of broad-antiprotozoan-spectrum drugs, which may meet the dual challenges posed by drug-resistant parasites and the rapid progression of protozoan illnesses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Emerging systems biology approaches in nanotoxicology: Towards a mechanism-based understanding of nanomaterial hazard and risk

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Pedro M.; Fadeel, Bengt, E-mail: Bengt.Fadeel@ki.se

    2016-05-15

    Engineered nanomaterials are being developed for a variety of technological applications. However, the increasing use of nanomaterials in society has led to concerns about their potential adverse effects on human health and the environment. During the first decade of nanotoxicological research, the realization has emerged that effective risk assessment of the multitudes of new nanomaterials would benefit from a comprehensive understanding of their toxicological mechanisms, which is difficult to achieve with traditional, low-throughput, single end-point oriented approaches. Therefore, systems biology approaches are being progressively applied within the nano(eco)toxicological sciences. This novel paradigm implies that the study of biological systems should be integrative resulting in quantitative and predictive models of nanomaterial behaviour in a biological system. To this end, global ‘omics’ approaches with which to assess changes in genes, proteins, metabolites, etc. are deployed allowing for computational modelling of the biological effects of nanomaterials. Here, we highlight omics and systems biology studies in nanotoxicology, aiming towards the implementation of a systems nanotoxicology and mechanism-based risk assessment of nanomaterials. - Highlights: • Systems nanotoxicology is a multi-disciplinary approach to quantitative modelling. • Transcriptomics, proteomics and metabolomics remain the most common methods. • Global “omics” techniques should be coupled to computational modelling approaches. • The discovery of nano-specific toxicity pathways and biomarkers is a prioritized goal. • Overall, experimental nanosafety research must endeavour reproducibility and relevance.

  18. Emerging systems biology approaches in nanotoxicology: Towards a mechanism-based understanding of nanomaterial hazard and risk

    International Nuclear Information System (INIS)

    Costa, Pedro M.; Fadeel, Bengt

    2016-01-01

    Engineered nanomaterials are being developed for a variety of technological applications. However, the increasing use of nanomaterials in society has led to concerns about their potential adverse effects on human health and the environment. During the first decade of nanotoxicological research, the realization has emerged that effective risk assessment of the multitudes of new nanomaterials would benefit from a comprehensive understanding of their toxicological mechanisms, which is difficult to achieve with traditional, low-throughput, single end-point oriented approaches. Therefore, systems biology approaches are being progressively applied within the nano(eco)toxicological sciences. This novel paradigm implies that the study of biological systems should be integrative resulting in quantitative and predictive models of nanomaterial behaviour in a biological system. To this end, global ‘omics’ approaches with which to assess changes in genes, proteins, metabolites, etc. are deployed allowing for computational modelling of the biological effects of nanomaterials. Here, we highlight omics and systems biology studies in nanotoxicology, aiming towards the implementation of a systems nanotoxicology and mechanism-based risk assessment of nanomaterials. - Highlights: • Systems nanotoxicology is a multi-disciplinary approach to quantitative modelling. • Transcriptomics, proteomics and metabolomics remain the most common methods. • Global “omics” techniques should be coupled to computational modelling approaches. • The discovery of nano-specific toxicity pathways and biomarkers is a prioritized goal. • Overall, experimental nanosafety research must endeavour reproducibility and relevance.

  19. Intragenic FMR1 disease-causing variants: a significant mutational mechanism leading to Fragile-X syndrome

    Science.gov (United States)

    Quartier, Angélique; Poquet, Hélène; Gilbert-Dussardier, Brigitte; Rossi, Massimiliano; Casteleyn, Anne-Sophie; Portes, Vincent des; Feger, Claire; Nourisson, Elsa; Kuentz, Paul; Redin, Claire; Thevenon, Julien; Mosca-Boidron, Anne-Laure; Callier, Patrick; Muller, Jean; Lesca, Gaetan; Huet, Frédéric; Geoffroy, Véronique; El Chehadeh, Salima; Jung, Matthieu; Trojak, Benoit; Le Gras, Stéphanie; Lehalle, Daphné; Jost, Bernard; Maury, Stéphanie; Masurel, Alice; Edery, Patrick; Thauvin-Robinet, Christel; Gérard, Bénédicte; Mandel, Jean-Louis; Faivre, Laurence; Piton, Amélie

    2017-01-01

    Fragile-X syndrome (FXS) is a frequent genetic form of intellectual disability (ID). The main recurrent mutagenic mechanism causing FXS is the expansion of a CGG repeat sequence in the 5′-UTR of the FMR1 gene, therefore, routinely tested in ID patients. We report here three FMR1 intragenic pathogenic variants not affecting this sequence, identified using high-throughput sequencing (HTS): a previously reported hemizygous deletion encompassing the last exon of FMR1, too small to be detected by array-CGH and inducing decreased expression of a truncated form of FMRP protein, in three brothers with ID (family 1) and two splice variants in boys with sporadic ID: a de novo variant c.990+1G>A (family 2) and a maternally inherited c.420-8A>G variant (family 3). After clinical reevaluation, the five patients presented features consistent with FXS (mean Hagerman's scores=15). We conducted a systematic review of all rare non-synonymous variants previously reported in FMR1 in ID patients and showed that six of them are convincing pathogenic variants. This study suggests that intragenic FMR1 variants, although much less frequent than CGG expansions, are a significant mutational mechanism leading to FXS and demonstrates the interest of HTS approaches to detect them in ID patients with a negative standard work-up. PMID:28176767

  20. A Poroelasticity Theory Approach to Study the Mechanisms Leading to Elevated Interstitial Fluid Pressure in Solid Tumours.

    Science.gov (United States)

    Burazin, Andrijana; Drapaca, Corina S; Tenti, Giuseppe; Sivaloganathan, Siv

    2018-05-01

    Although the mechanisms responsible for elevated interstitial fluid pressure (IFP) in tumours remain obscure, it seems clear that high IFP represents a barrier to drug delivery (since the resulting adverse pressure gradient implies a reduction in the driving force for transvascular exchange of both fluid and macromolecules). R. Jain and co-workers studied this problem, and although the conclusions drawn from their idealized mathematical models offered useful insights into the causes of elevated IFP, they by no means gave a definitive explanation for this phenomenon. In this paper, we use poroelasticity theory to also develop a macroscopic mathematical model to describe the time evolution of a solid tumour, but focus our attention on the mechanisms responsible for the rise of the IFP, from that for a healthy interstitium to that measured in malignant tumours. In particular, we discuss a number of possible time scales suggested by our mathematical model and propose a tumour-dependent time scale that leads to results in agreement with experimental observations. We apply our mathematical model to simulate the effect of "vascular normalization" (as proposed by Jain in Nat Med 7:987-989, 2001) on the IFP profile and discuss and contrast our conclusions with those of previous work in the literature.

  1. Lead ultra-trace on-line preconcentration and determination using selective solid phase extraction and electrothermal atomic absorption spectrometry: applications in seawaters and biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Vereda Alonso, E.; Siles Cordero, M.T.; Garcia de Torres, A.; Cano Pavon, J.M. [University of Malaga, Department of Analytical Chemistry Faculty of Sciences, Malaga (Spain)

    2006-08-15

    In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 Aa; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO{sub 3}, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml{sup -1} of lead. At a sample frequency of 36 h{sup -1} with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml{sup -1}, respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml{sup -1}). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too. (orig.)

  2. Energy production from mechanical biological treatment and Composting plants exploiting solid anaerobic digestion batch: An Italian case study

    International Nuclear Information System (INIS)

    Di Maria, F.; Sordi, A.; Micale, C.

    2012-01-01

    Highlights: ► This work quantifies the Italian Composting and MBT facilities upgradable by SADB. ► The bioCH 4 from SADB of source and mechanical selected OFMSW is of 220–360 Nl/kg VS. ► The upgrading investment cost is 30% higher for Composting than for MBT. ► Electricity costs are 0.11–0.28 €/kW h, not influenced by differentiate collection. ► Electrical energy costs are constant for SADB treating more than 30 ktons/year. - Abstract: The energetic potential of the organic fraction of municipal solid waste processed in both existing Composting plants and Mechanical Biological Treatment (MBT) plants, can be successfully exploited by retrofitting these plants with the solid anaerobic digestion batch process. On the basis of the analysis performed in this study, about 50 MBT plants and 35 Composting plants were found to be suitable for retrofitting with Solid Anaerobic Digestion Batch (SADB) facilities. Currently the organic fraction of Municipal Solid Waste (OFMSW) arising from the MBT facilities is about 1,100,000 tons/year, whereas that arising from differentiated collection and treated in Composting plants is about 850,000 tons/year. The SADB performances were analyzed by the aid of an experimental apparatus and the main results, in agreement with literature data, show that the biogas yield ranged from 400 to 650 Nl/kg of Volatile Solids (VS), with a methane content ranging from 55% to 60% v/v. This can lead to the production of about 500 GW h of renewable energy per year, giving a CO 2 reduction of about 270,000 tons/year. From the economic point of view, the analysis shows that the mean cost of a kW h of electrical energy produced by upgrading MBT and Composting facilities with the SADB, ranges from 0.11 and 0.28 €/kW h, depending on the plant size and the amount of waste treated.

  3. Biological Mechanisms Whereby Social Exclusion May Contribute to the Etiology of Psychosis: A Narrative Review.

    Science.gov (United States)

    Selten, Jean-Paul; Booij, Jan; Buwalda, Bauke; Meyer-Lindenberg, Andreas

    2017-01-03

    The purpose of this review is to examine whether a contribution of social exclusion to the pathogenesis of psychosis is compatible with the dopamine hypothesis and/or the neurodevelopmental hypothesis. Humans experience social exclusion as defeating. An animal model for defeat is the resident-intruder paradigm. The defeated animal shows evidence of an increased sensitivity to amphetamine, increased dopamine release in the nucleus accumbens and prefrontal cortex, and increased firing of dopaminergic neurons in the ventral tegmental area. As for humans, one study showed that amphetamine-induced striatal dopamine release was significantly greater among nonpsychotic young adults with severe hearing impairment than among normal hearing controls. Two other studies reported an association between childhood trauma and increased dopamine function in striatal subregions. Several studies have suggested that the perigenual anterior cingulate cortex (pgACC) may play a role in the processing of social stress. Importantly, the pgACC regulates the activity of the ventral striatum through bidirectional interconnections. We are not aware of studies in humans that examined whether (proxies for) social exclusion contributes to the structural brain changes present at psychosis onset. Animal studies, however, reported that long-term isolation may lead to reductions in volume of the total brain, hippocampus, or medial prefrontal cortex. Other animal studies reported that social defeat can reduce neurogenesis. In conclusion, the answer to the question as to whether there are plausible mechanisms whereby social exclusion can contribute to the pathogenesis of psychosis is cautiously affirmative. © The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

    Energy Technology Data Exchange (ETDEWEB)

    Cimpan, Ciprian, E-mail: cic@kbm.sdu.dk; Wenzel, Henrik

    2013-07-15

    Highlights: • Compared systems achieve primary energy savings between 34 and 140 MJ{sub primary}/100 MJ{sub input} {sub waste.} • Savings magnitude is foremost determined by chosen primary energy and materials production. • Energy consumption and process losses can be upset by increased technology efficiency. • Material recovery accounts for significant shares of primary energy savings. • Direct waste-to-energy is highly efficient if cogeneration (CHP) is possible. - Abstract: Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJ{sub primary}/100 MJ{sub input} {sub waste}, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat

  5. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)

    International Nuclear Information System (INIS)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-01-01

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L"−"1). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ_P_S_I_I) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos loads

  6. Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

    International Nuclear Information System (INIS)

    Cimpan, Ciprian; Wenzel, Henrik

    2013-01-01

    Highlights: • Compared systems achieve primary energy savings between 34 and 140 MJ primary /100 MJ input waste. • Savings magnitude is foremost determined by chosen primary energy and materials production. • Energy consumption and process losses can be upset by increased technology efficiency. • Material recovery accounts for significant shares of primary energy savings. • Direct waste-to-energy is highly efficient if cogeneration (CHP) is possible. - Abstract: Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJ primary /100 MJ input waste , in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS

  7. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Anderson, Bruce [Department of Civil Engineering, Queen' s University, Kingston K7L3N6 (Canada); Cheng, Shuiping, E-mail: shpcheng@tongji.edu.cn [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L{sup −1}). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ{sub PSII}) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos

  8. Interpretation of biological and mechanical variations between the Lowry versus Bradford method for protein quantification

    OpenAIRE

    Tzong-Shi Lu; Szu-Yu Yiao; Kenneth Lim; Roderick V. Jensen; Li-Li Hsiao

    2010-01-01

    Background: The identification of differences in protein expression resulting from methodical variations is an essential component to the interpretation of true, biologically significant results. Aims: We used the Lowry and Bradford methods- two most commonly used methods for protein quantification, to assess whether differential protein expressions are a result of true biological or methodical variations. Material & Methods: Differential protein expression patterns was assessed by western bl...

  9. Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

    OpenAIRE

    Wang, B; Yang, W; McKittrick, J; Meyers, MA

    2016-01-01

    © 2015 Elsevier Ltd. A ubiquitous biological material, keratin represents a group of insoluble, usually high-sulfur content and filament-forming proteins, constituting the bulk of epidermal appendages such as hair, nails, claws, turtle scutes, horns, whale baleen, beaks, and feathers. These keratinous materials are formed by cells filled with keratin and are considered 'dead tissues'. Nevertheless, they are among the toughest biological materials, serving as a wide variety of interesting func...

  10. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Marcelino; Costa, Thiago [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Rocha, Otávio [Federal Institute of Education, Science and Technology of Pará — IFPA, 66093-020 Belém, PA (Brazil); Spinelli, José E. [Department of Materials Engineering, Federal University of São Carlos — UFSCar, 13565-905 São Carlos, SP (Brazil); Cheung, Noé, E-mail: cheung@fem.unicamp.br [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Garcia, Amauri [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil)

    2015-08-15

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing.

  11. Preliminary treatment of chlorinated streams containing fission products: mechanisms leading to crystalline phases in molten chloride media

    International Nuclear Information System (INIS)

    Hudry, D.

    2008-10-01

    The world of the nuclear power gets ready for profound modifications so that 'the atom' can aspire in conformance with long-lasting energy: it is what we call the development of generation IV nuclear systems. So, the new pyrochemical separation processes for the spent fuel reprocessing are currently being investigated. Techniques in molten chloride media generate an ultimate flow (with high chlorine content) which cannot be incorporated in conventional glass matrices. This flow is entirely water-soluble and must be conditioned in a chemical form which is compatible with a long-term disposal. This work of thesis consists in studying new ways for the management of the chlorinated streams loaded with fission products (FP). To do it, a strategy of selective FP extraction via the in situ formation of crystalline phases was retained. The possibility of extracting rare earths in the eutectic LiCl-KCl was demonstrated via the development of a new way of synthesis of rare earth phosphates (TRPO 4 ). As regards alkaline earths, the conversion of strontium and barium chlorides to the corresponding tungstates or molybdates was studied in different solvents. Mechanisms leading to the crystalline phases in molten chloride media were studied via the coupling of NMR and XRD techniques. First of all, it has been shown that these mechanisms are dependent on the stability of the used precursors. So in the case of the formation of rare earth phosphates the solvent is chemically active. On the other hand, in the case of the formation of alkaline earth tungstates it would seem that the solvent plays the role of structuring agent which can control the ability to react of chlorides. (author)

  12. A combination of shear and dynamic compression leads to mechanically induced chondrogenesis of human mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    O Schätti

    2011-10-01

    Full Text Available ere is great interest in how bone marrow derived stem cells make fate decisions. Numerous studies have investigated the role of individual growth factors on mesenchymal stem cell differentiation, leading to protocols for cartilage, bone and adipose tissue. However, these protocols overlook the role of biomechanics on stem cell differentiation. There have been various studies that have applied mechanical stimulation to constructs containing mesenchymal stem cells, with varying degrees of success. One critical fate decision is that between cartilage and bone. Articular motion is a combination of compressive, tensile and shear deformations; therefore, one can presume that compression alone is unlikely to be a sufficient mechanical signal to generate a cartilage-like tissue in vitro. Within this study, we aimed to determine the role of shear on the fate of stem cell differentiation. Specifically, we investigated the potential enhancing effect of surface shear, superimposed on cyclic axial compression, on chondrogenic differentiation of human bone marrow-derived stem cells. Using a custom built loading device we applied compression, shear or a combination of both stimuli onto fibrin/polyurethane composites in which human mesenchymal stem cells were embedded, while no exogenous growth-factors were added to the culture medium. Both compression or shear alone was insufficient for the chondrogenic induction of human mesenchymal stem cells. However, the application of shear superimposed upon dynamic compression led to significant increases in chondrogenic gene expression. Histological analysis detected sulphated glycosaminoglycan and collagen II only in the compression and shear group. The results obtained may provide insight into post-operative care after cell therapy involving mesenchymal stromal cells.

  13. Does a plant for mechanical-biological waste treatment require a sanitary landfill?; Braucht die MBA eine Deponie?

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, Burkart [GVoA mbH und Co. KG, Hille (Germany)

    2012-11-01

    In mechanical-biological waste treatment, an interesting recyclable fraction is dumped in landfill together with other treatment residues. This may be 10-20% depending on the energy content of the initial material. Some operators of mechanical-biological waste treatment plants are currently working on modifying their waste treatment processes. Results so far have shown that this may also reduce the cost. (orig.) [German] Bei der bisherigen Abfallentsorgung mittels einer MBA (mechanisch-biologische Abfallbehandlung) wird immer noch ein interessanter Wertstoffanteil mit dem Deponat auf der Deponie abgelagert. Je nach Qualitaet der Vorbehandlung sind dies alleine vom Energieinhalt des Eingangsmaterials ca. 10-20%. Um auch diesen Anteil zu verwerten, sind aktuell einige MBA-Betreiber dabei, ihre Verfahren entsprechend umzustellen. Erste Ergebnisse zeigen, dass dies auch noch zu Kosteneinsparungen fuehren kann. (orig.)

  14. MODELLING OF RING-SHAPED ULTRASONIC WAVEGUIDES FOR TESTING OF MECHANICAL PROPERTIES AND THERAPEUTIC TREATMENT OF BIOLOGICAL TISSUES

    Directory of Open Access Journals (Sweden)

    V. T. Minchenya

    2011-01-01

    Full Text Available The article presents results of modelling of ring-shaped waveguide tool for ultrasonic treatment of biological materials, particularly malignant tumours, and testing of their mechanical properties. Harmonic analysis of forced flexural vibration of the waveguide using ANSYS software and APDL programming language was implemented for determination of waveguide geometric parameters providing its resonance for the given excitation frequency. The developed finite element model accounts for interaction between the waveguide and tumour tissue as well as initial prestressing of tissue radially compressed by the waveguide. Resonant curves of the waveguide in terms of its thickness and diameter are calculated and presented. Principle of application of the developed modeling technique for extraction of diagnostic data on mechanical properties of biological tissues is described.

  15. Mechanical and biological properties of the micro-/nano-grain functionally graded hydroxyapatite bioceramics for bone tissue engineering.

    Science.gov (United States)

    Zhou, Changchun; Deng, Congying; Chen, Xuening; Zhao, Xiufen; Chen, Ying; Fan, Yujiang; Zhang, Xingdong

    2015-08-01

    Functionally graded materials (FGM) open the promising approach for bone tissue repair. In this study, a novel functionally graded hydroxyapatite (HA) bioceramic with micrograin and nanograin structure was fabricated. Its mechanical properties were tailored by composition of micrograin and nanograin. The dynamic mechanical analysis (DMA) indicated that the graded HA ceramics had similar mechanical property compared to natural bones. Their cytocompatibility was evaluated via fluorescent microscopy and MTT colorimetric assay. The viability and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs) on ceramics indicated that this functionally graded HA ceramic had better cytocompatibility than conventional HA ceramic. This study demonstrated that functionally graded HA ceramics create suitable structures to satisfy both the mechanical and biological requirements of bone tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Biological and Chemical Removal of Primary Cilia Affects Mechanical Activation of Chondrogenesis Markers in Chondroprogenitors and Hypertrophic Chondrocytes.

    Science.gov (United States)

    Deren, Matthew E; Yang, Xu; Guan, Yingjie; Chen, Qian

    2016-02-04

    Chondroprogenitors and hypertrophic chondrocytes, which are the first and last stages of the chondrocyte differentiation process, respectively, are sensitive to mechanical signals. We hypothesize that the mechanical sensitivity of these cells depends on the cell surface primary cilia. To test this hypothesis, we removed the primary cilia by biological means with transfection with intraflagellar transport protein 88 (IFT88) siRNA or by chemical means with chloral hydrate treatment. Transfection of IFT88 siRNA significantly reduced the percentage of ciliated cells in both chondroprogenitor ATDC5 cells as well as primary hypertrophic chondrocytes. Cyclic loading (1 Hz, 10% matrix deformation) of ATDC5 cells in three-dimensional (3D) culture stimulates the mRNA levels of chondrogenesis marker Type II collagen (Col II), hypertrophic chondrocyte marker Type X collagen (Col X), and a molecular regulator of chondrogenesis and chondrocyte hypertrophy bone morphogenetic protein 2 (BMP-2). The reduction of ciliated chondroprogenitors abolishes mechanical stimulation of Col II, Col X, and BMP-2. In contrast, cyclic loading stimulates Col X mRNA levels in hypertrophic chondrocytes, but not those of Col II and BMP-2. Both biological and chemical reduction of ciliated hypertrophic chondrocytes reduced but failed to abolish mechanical stimulation of Col X mRNA levels. Thus, primary cilia play a major role in mechanical stimulation of chondrogenesis and chondrocyte hypertrophy in chondroprogenitor cells and at least a partial role in hypertrophic chondrocytes.

  17. Biological and Chemical Removal of Primary Cilia Affects Mechanical Activation of Chondrogenesis Markers in Chondroprogenitors and Hypertrophic Chondrocytes

    Directory of Open Access Journals (Sweden)

    Matthew E. Deren

    2016-02-01

    Full Text Available Chondroprogenitors and hypertrophic chondrocytes, which are the first and last stages of the chondrocyte differentiation process, respectively, are sensitive to mechanical signals. We hypothesize that the mechanical sensitivity of these cells depends on the cell surface primary cilia. To test this hypothesis, we removed the primary cilia by biological means with transfection with intraflagellar transport protein 88 (IFT88 siRNA or by chemical means with chloral hydrate treatment. Transfection of IFT88 siRNA significantly reduced the percentage of ciliated cells in both chondroprogenitor ATDC5 cells as well as primary hypertrophic chondrocytes. Cyclic loading (1 Hz, 10% matrix deformation of ATDC5 cells in three-dimensional (3D culture stimulates the mRNA levels of chondrogenesis marker Type II collagen (Col II, hypertrophic chondrocyte marker Type X collagen (Col X, and a molecular regulator of chondrogenesis and chondrocyte hypertrophy bone morphogenetic protein 2 (BMP-2. The reduction of ciliated chondroprogenitors abolishes mechanical stimulation of Col II, Col X, and BMP-2. In contrast, cyclic loading stimulates Col X mRNA levels in hypertrophic chondrocytes, but not those of Col II and BMP-2. Both biological and chemical reduction of ciliated hypertrophic chondrocytes reduced but failed to abolish mechanical stimulation of Col X mRNA levels. Thus, primary cilia play a major role in mechanical stimulation of chondrogenesis and chondrocyte hypertrophy in chondroprogenitor cells and at least a partial role in hypertrophic chondrocytes.

  18. Plant polyphenols mobilize nuclear copper in human peripheral lymphocytes leading to oxidatively generated DNA breakage: implications for an anticancer mechanism.

    Science.gov (United States)

    Shamim, Uzma; Hanif, Sarmad; Ullah, M F; Azmi, Asfar S; Bhat, Showket H; Hadi, S M

    2008-08-01

    It was earlier proposed that an important anti-cancer mechanism of plant polyphenols may involve mobilization of endogenous copper ions, possibly chromatin-bound copper and the consequent pro-oxidant action. This paper shows that plant polyphenols are able to mobilize nuclear copper in human lymphocytes, leading to degradation of cellular DNA. A cellular system of lymphocytes isolated from human peripheral blood and comet assay was used for this purpose. Incubation of lymphocytes with neocuproine (a cell membrane permeable copper chelator) inhibited DNA degradation in intact lymphocytes. Bathocuproine, which is unable to permeate through the cell membrane, did not cause such inhibition. This study has further shown that polyphenols are able to degrade DNA in cell nuclei and that such DNA degradation is inhibited by neocuproine as well as bathocuproine (both of which are able to permeate the nuclear pore complex), suggesting that nuclear copper is mobilized in this reaction. Pre-incubation of lymphocyte nuclei with polyphenols indicates that it is capable of traversing the nuclear membrane. This study has also shown that polyphenols generate oxidative stress in lymphocyte nuclei which is inhibited by scavengers of reactive oxygen species (ROS) and neocuproine. These results indicate that the generation of ROS occurs through mobilization of nuclear copper resulting in oxidatively generated DNA breakage.

  19. Applicability of cloud point extraction for the separation trace amount of lead ion in environmental and biological samples prior to determination by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Sayed Zia Mohammadi

    2016-09-01

    Full Text Available A sensitive cloud point extraction procedure(CPE for the preconcentration of trace lead prior to its determination by flame atomic absorption spectrometry (FAAS has been developed. The CPE method is based on the complex of Pb(II ion with 1-(2-pyridylazo-2-naphthol (PAN, and then entrapped in the non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of PAN and Triton X-114, equilibration temperature and time, were investigated in detail. A preconcentration factor of 30 was obtained for the preconcentration of Pb(II ion with 15.0 mL solution. Under the optimal conditions, the calibration curve was linear in the range of 7.5 ng mL−1–3.5 μg mL−1 of lead with R2 = 0.9998 (n = 10. Detection limit based on three times the standard deviation of the blank (3Sb was 5.27 ng mL−1. Eight replicate determinations of 1.0 μg mL−1 lead gave a mean absorbance of 0.275 with a relative standard deviation of 1.6%. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method has been applied for determination of trace amounts of lead in biological and water samples with satisfactory results.

  20. Neuroimaging mechanisms of change in psychotherapy for addictive behaviors: emerging translational approaches that bridge biology and behavior.

    Science.gov (United States)

    Feldstein Ewing, Sarah W; Chung, Tammy

    2013-06-01

    Research on mechanisms of behavior change provides an innovative method to improve treatment for addictive behaviors. An important extension of mechanisms of change research involves the use of translational approaches, which examine how basic biological (i.e., brain-based mechanisms) and behavioral factors interact in initiating and sustaining positive behavior change as a result of psychotherapy. Articles in this special issue include integrative conceptual reviews and innovative empirical research on brain-based mechanisms that may underlie risk for addictive behaviors and response to psychotherapy from adolescence through adulthood. Review articles discuss hypothesized mechanisms of change for cognitive and behavioral therapies, mindfulness-based interventions, and neuroeconomic approaches. Empirical articles cover a range of addictive behaviors, including use of alcohol, cigarettes, marijuana, cocaine, and pathological gambling and represent a variety of imaging approaches including fMRI, magneto-encephalography, real-time fMRI, and diffusion tensor imaging. Additionally, a few empirical studies directly examine brain-based mechanisms of change, whereas others examine brain-based indicators as predictors of treatment outcome. Finally, two commentaries discuss craving as a core feature of addiction, and the importance of a developmental approach to examining mechanisms of change. Ultimately, translational research on mechanisms of behavior change holds promise for increasing understanding of how psychotherapy may modify brain structure and functioning and facilitate the initiation and maintenance of positive treatment outcomes for addictive behaviors. 2013 APA, all rights reserved

  1. Electron spin interactions in chemistry and biology fundamentals, methods, reactions mechanisms, magnetic phenomena, structure investigation

    CERN Document Server

    Likhtenshtein, Gertz

    2016-01-01

    This book presents the versatile and pivotal role of electron spin interactions in nature. It provides the background, methodologies and tools for basic areas related to spin interactions, such as spin chemistry and biology, electron transfer, light energy conversion, photochemistry, radical reactions, magneto-chemistry and magneto-biology. The book also includes an overview of designing advanced magnetic materials, optical and spintronic devices and photo catalysts. This monograph appeals to scientists and graduate students working in the areas related to spin interactions physics, biophysics, chemistry and chemical engineering.

  2. Evaluation of potential reaction mechanisms leading to the formation of coniferyl alcohol α-linkages in lignin: a density functional theory study.

    Science.gov (United States)

    Watts, Heath D; Mohamed, Mohamed Naseer Ali; Kubicki, James D

    2011-12-21

    Five potential reaction mechanisms, each leading to the formation of an α-O-4-linked coniferyl alcohol dimer, and one scheme leading to the formation of a recently proposed free-radical coniferyl alcohol trimer were assessed using density functional theory (DFT) calculations. These potential reaction mechanisms were evaluated using both the calculated Gibbs free energies, to predict the spontaneity of the constituent reactions, and the electron-density mapped Fukui function, to determine the most reactive sites of each intermediate species. The results indicate that each reaction in one of the six mechanisms is thermodynamically favorable to those in the other mechanisms; what is more, the Fukui function for each free radical intermediate corroborates with the thermochemical results for this mechanism. This mechanism proceeds via the formation of two distinct free-radical intermediates, which then react to produce the four α-O-4 stereoisomers.

  3. Clinical indications and biological mechanisms of splenic irradiation in autoimmune diseases

    Energy Technology Data Exchange (ETDEWEB)

    Weinmann, M.; Becker, G. [Tuebingen Univ. (Germany). Abt. fuer Strahlenonkologie; Einsele, H.; Bamberg, M. [Tuebingen Univ. (Germany). Abt. fuer Innere Medizin 2

    2001-02-01

    Background: Splenic irradiation (SI) is a fairly unknown treatment modality in autoimmune disorders like autoimmune thrombocytopenia (AIT) or autoimmune hemolytic anemia (AIHA), which may provide an effective, low toxic and cost-effective treatment for selected patients. Patients, Materials and Methods: This article reviews the limited experiences on splenic irradiation in autoimmune thrombocytopenia by analyzing the current studies including 71 patients and some preliminary reports on splenic irradiation in autoimmune hemolytic anemia. Results: In autoimmune thrombocytopenia between 40 and 90% of all patients responded, but most of them relapsed within 4 to 6 months after splenic irradiation. Between 10 and 20% of all patients had a sustained response. The efficacy of splenic irradiation in HIV-associated cases of thrombocytopenia is probably lower than in other forms of autoimmune thrombocytopenia, but especially in this group immunosuppressive drug treatment of autoimmune thrombocytopenia exposes some problems. In autoimmune hemolytic anemia there are some case reports about efficacy of splenic irradiation. Toxicity of splenic irradiation in both diseases was very moderate. Conclusions: For HIV patients, for elderly patients or patients at high risk for complications following splenectomy splenic irradiation might be a treatment option. Splenic irradiation as preoperative treatment in patients not responding to or not suitable for immunosuppressive drugs prior to splenectomy may be a promising new application of splenic irradiation to reduce adverse effects of splenectomy in thrombocytopenic patients. A further analysis of the biological mechanisms underlying splenic irradiation may help to improve patient selection, to optimize dose concepts and treatment schedules and will improve understanding of radiotherapy as an immunomodulatory treatment modality. (orig.) [German] Hintergrund: Die Bestrahlung der Milz zur Behandlung von haematologischen

  4. An experimental study of double-peeling mechanism inspired by biological adhesive systems

    DEFF Research Database (Denmark)

    Heepe, Lars; Raguseo, Saverio; Gorb, Stanislav N.

    2017-01-01

    Double- (or multiple-) peeling systems consist of two (or numerous) tapes adhering to a substrate and having a common hinge, where the pulling force is applied. Biological systems, consisting of tape-like (or spatula-like) contact elements, are widely observed in adhesive pads of flies, beetles...

  5. Bobbing of Oxysterols: Molecular Mechanism for Translocation of Tail-Oxidized Sterols through Biological Membranes

    Czech Academy of Sciences Publication Activity Database

    Kulig, W.; Mikkolainen, H.; Olžyńska, Agnieszka; Jurkiewicz, Piotr; Cwiklik, Lukasz; Hof, Martin; Vattulainen, I.; Jungwirth, Pavel; Rog, T.

    2018-01-01

    Roč. 9, č. 5 (2018), s. 1118-1123 ISSN 1948-7185 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : biological membranes * alcohols * cell membranes Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 9.353, year: 2016

  6. Structure and mechanism leading to formation of the cysteine sulfinate product complex of a biomimetic cysteine dioxygenase model.

    Science.gov (United States)

    Sallmann, Madleen; Kumar, Suresh; Chernev, Petko; Nehrkorn, Joscha; Schnegg, Alexander; Kumar, Devesh; Dau, Holger; Limberg, Christian; de Visser, Sam P

    2015-05-11

    Cysteine dioxygenase is a unique nonheme iron enzyme that is involved in the metabolism of cysteine in the body. It contains an iron active site with an unusual 3-His ligation to the protein, which contrasts with the structural features of common nonheme iron dioxygenases. Recently, some of us reported a truly biomimetic model for this enzyme, namely a trispyrazolylborato iron(II) cysteinato complex, which not only has a structure very similar to the enzyme-substrate complex but also represents a functional model: Treatment of the model with dioxygen leads to cysteine dioxygenation, as shown by isolating the cysteine part of the product in the course of the work-up. However, little is known on the conversion mechanism and, so far, not even the structure of the actual product complex had been characterised, which is also unknown in case of the enzyme. In a multidisciplinary approach including density functional theory calculations and X-ray absorption spectroscopy, we have now determined the structure of the actual sulfinato complex for the first time. The Cys-SO2 (-) functional group was found to be bound in an η(2) -O,O-coordination mode, which, based on the excellent resemblance between model and enzyme, also provides the first support for a corresponding binding mode within the enzymatic product complex. Indeed, this is again confirmed by theory, which had predicted a η(2) -O,O-binding mode for synthetic as well as the natural enzyme. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Adipose tissue NAD+ biology in obesity and insulin resistance: From mechanism to therapy.

    Science.gov (United States)

    Yamaguchi, Shintaro; Yoshino, Jun

    2017-05-01

    Nicotinamide adenine dinucleotide (NAD + ) biosynthetic pathway, mediated by nicotinamide phosphoribosyltransferase (NAMPT), a key NAD + biosynthetic enzyme, plays a pivotal role in controlling many biological processes, such as metabolism, circadian rhythm, inflammation, and aging. Over the past decade, NAMPT-mediated NAD + biosynthesis, together with its key downstream mediator, namely the NAD + -dependent protein deacetylase SIRT1, has been demonstrated to regulate glucose and lipid metabolism in a tissue-dependent manner. These discoveries have provided novel mechanistic and therapeutic insights into obesity and its metabolic complications, such as insulin resistance, an important risk factor for developing type 2 diabetes and cardiovascular disease. This review will focus on the importance of adipose tissue NAMPT-mediated NAD + biosynthesis and SIRT1 in the pathophysiology of obesity and insulin resistance. We will also critically explore translational and clinical aspects of adipose tissue NAD + biology. © 2017 WILEY Periodicals, Inc.

  8. Structure property relationship of biological nano composites studies by combination of in-situ synchrotron scattering and mechanical tests

    International Nuclear Information System (INIS)

    Martinschitz, K.

    2005-06-01

    Biological materials represent hierarchical nano fibre composites with complicated morphology and architecture varying on the nm level. The mechanical response of those materials is influenced by many parameters like chemical composition and crystal structure of constituents, preferred orientation, internal morphology with specific sizes of features etc. In-situ wide-angle x-ray scattering (WAXS) combined with mechanical tests provide a unique means to evaluate structural changes in biological materials at specific stages of tensile experiments. In this way it is possible to identify distinct architectural/compositional elements responsible for specific mechanical characteristics of the biological materials. In this thesis, structure-property relationship is analyzed using in-situ WAXS in the tissues of Picea abies, coir fibre, bacterial cellulose and cellulose II based composites. The experiments were performed at the beamline ID01 of European synchrotron radiation facility in Grenoble, France. The tissues were strained in a tensile stage, while the structural changes were monitored using WAXS. Complex straining procedures were applied including cyclic straining. One of the main goals was to understand the stiffness recovery and strain hardening effects in the tissues. The results demonstrate that, in all cellulosics, the orientation of the cellulose crystallites is only the function of the external strain while the stiffness depends on the specific stage of the tensile experiment. Whenever the strain is increased, the tissues exhibit stiffness equal or larger than the initial one. The recovery of the mechanical function is attributed to the molecular mechanistic effects operating between the crystalline domains of the cellulose. (author)

  9. Stabilization of organic matter and nitrogen immobilization during mechanical-biological treatment and landfilling of residual municipal solid waste

    International Nuclear Information System (INIS)

    Heiss-Ziegler, C.

    2000-04-01

    Synthesis of humic substances and nitrogen immobilization during mechanical-biological treatment of waste and the behavior of biologically stabilized waste under anaerobic landfill conditions were investigated. Samples were taken from a large-scale treatment plant. Anaerobic conditions were simulated in lab scale test cells. Humic substances were analyzed photometrically and gravimetrically. The nitrogen immobilization was investigated by sequential leaching tests and by analyzing the non acid hydrolyzable nitrogen. Humic acids were mainly synthesized during the beginning of the intensive rotting phase. Later on in the process no significant changes occurred. The humic acid content rose up to 6,8 % DS org. It correlated well with the stability parameters respiration activity and accumulated gas production. In the coarse of the treatment the nitrogen load emitted during the consecutive leaching tests dropped from 50 % down to less than 20 % total nitrogen. The non acid hydrolyzable nitrogen rose from 17 up to 42 % Kjeldahl nitrogen content. Nevertheless the mechanical-biological treatment is not significantly shortening the aftercare period of a landfill concerning liquid nitrogen emissions. The reduced nitrogen emission potential is released more slowly. When reactive waste material was exposed to anaerobic conditions, humic and fulvic acids were synthesized up to the point when intensive gas production started and then were remineralized. Stabilized waste materials after treatment of various intensity behaved differently under anaerobic conditions. Steady and decreasing humic acid contents were observed. (author)

  10. The Role of Biologically Active Ingredients from Natural Drug Treatments for Arrhythmias in Different Mechanisms

    OpenAIRE

    Li, Jie; Hu, Dan; Song, Xiaoli; Han, Tao; Gao, Yonghong; Xing, Yanwei

    2017-01-01

    Arrhythmia is a disease that is caused by abnormal electrical activity in the heart rate or rhythm. It is the major cause of cardiovascular morbidity and mortality. Although several antiarrhythmic drugs have been used in clinic for decades, their application is often limited by their adverse effects. As a result, natural drugs, which have fewer side effects, are now being used to treat arrhythmias. We searched for all articles on the role of biologically active ingredients from natural drug t...

  11. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion

    Czech Academy of Sciences Publication Activity Database

    Slavík, M.; Bruthans, J.; Filippi, Michal; Schweigstillová, Jana; Falteisek, L.; Řihošek, J.

    2017-01-01

    Roč. 278, FEB 1 (2017), s. 298-313 ISSN 0169-555X R&D Projects: GA ČR GA13-28040S; GA ČR(CZ) GA16-19459S Institutional support: RVO:67985831 ; RVO:67985891 Keywords : biofilm * biocrust * biologically-initiated rock crust * sandstone protection * case hardening Subject RIV: DB - Geology ; Mineralogy; DB - Geology ; Mineralogy (USMH-B) OBOR OECD: Geology; Geology (USMH-B) Impact factor: 2.958, year: 2016

  12. Systems biology: An emerging strategy for discovering novel pathogenetic mechanisms that promote cardiovascular disease

    OpenAIRE

    Maron, Bradley A.; Leopold, Jane A.

    2016-01-01

    Reductionist theory proposes that analyzing complex systems according to their most fundamental components is required for problem resolution, and has served as the cornerstone of scientific methodology for more than four centuries. However, technological gains in the current scientific era now allow for the generation of large datasets that profile the proteomic, genomic, and metabolomic signatures of biological systems across a range of conditions. The accessibility of data on such a vast s...

  13. Combined Biological and Chemical Mechanisms for Degradation of Insensitive Munitions in the Presence of Alternate Explosives

    Science.gov (United States)

    2017-06-21

    substrate for respiration or fermentation , a process called endogenous respiration and endogenous fermentation respectively. In most treatments with...commercial product, process , or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement...showed that DNAN can be readily reduced by chemical and biological processes at pH 7 within 24 hours, and at pH 8 and 9 in

  14. Interpretation of biological and mechanical variations between the Lowry versus Bradford method for protein quantification.

    Science.gov (United States)

    Lu, Tzong-Shi; Yiao, Szu-Yu; Lim, Kenneth; Jensen, Roderick V; Hsiao, Li-Li

    2010-07-01

    The identification of differences in protein expression resulting from methodical variations is an essential component to the interpretation of true, biologically significant results. We used the Lowry and Bradford methods- two most commonly used methods for protein quantification, to assess whether differential protein expressions are a result of true biological or methodical variations. MATERIAL #ENTITYSTARTX00026; Differential protein expression patterns was assessed by western blot following protein quantification by the Lowry and Bradford methods. We have observed significant variations in protein concentrations following assessment with the Lowry versus Bradford methods, using identical samples. Greater variations in protein concentration readings were observed over time and in samples with higher concentrations, with the Bradford method. Identical samples quantified using both methods yielded significantly different expression patterns on Western blot. We show for the first time that methodical variations observed in these protein assay techniques, can potentially translate into differential protein expression patterns, that can be falsely taken to be biologically significant. Our study therefore highlights the pivotal need to carefully consider methodical approaches to protein quantification in techniques that report quantitative differences.

  15. The mechanism of cysteine detection in biological media by means of vanadium oxide nanoparticles

    International Nuclear Information System (INIS)

    Bezerra, A. G.; Barison, A.; Oliveira, V. S.; Foti, L.; Krieger, M. A.; Dhalia, R.; Viana, I. F. T.; Schreiner, W. H.

    2012-01-01

    We report on the interaction of vanadate nanoparticles, produced using the laser ablation in liquids synthesis, with cysteine in biological molecules. Cysteine is a very important amino acid present in most proteins, but also because cysteine and the tripeptide glutathione are the main antioxidant molecules in our body system. Detailed UV–Vis absorption spectra and dynamic light scattering measurements were done to investigate the detection of cysteine in large biological molecules. The intervalence band of the optical absorption spectra shows capability for quantitative cysteine sensing in the μM range in biological macromolecules. Tests included cytoplasmic repetitive antigen and flagellar repetitive antigen proteins of the Trypanosoma cruzi protozoa, as well as the capsid p24 proteins from Human Immunodeficiency Virus type 1 and type 2. Detailed NMR measurements for hydrogen, carbon, and vanadium nuclei show that cysteine in contact with the vanadate looses hydrogen of the sulphydryl side chain, while the vanadate is reduced. The subsequent detachment of two deprotonated molecules to form cystine and the slow return to the vanadate complete the oxidation–reduction cycle. Therefore, the vanadate acts as a charge exchanging catalyst on cysteine to form cystine. The NMR results also indicate that the nanoparticles are not formed by the common orthorhombic V 2 O 5 form.

  16. The mechanism of cysteine detection in biological media by means of vanadium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, A. G. [Universidade Tecnologica Federal do Parana, Departamento Academico de Fisica (Brazil); Barison, A. [Universidade Federal do Parana, Departamento de Quimica (Brazil); Oliveira, V. S. [Universidade Federal do Parana, Departamento de Fisica (Brazil); Foti, L.; Krieger, M. A. [Fundacao Oswaldo Cruz, Instituto de Biologia Molecular do Parana (Brazil); Dhalia, R.; Viana, I. F. T. [Fundacao Oswaldo Cruz, Centro de Pesquisas Aggeu Magalhaes (Brazil); Schreiner, W. H., E-mail: wido@fisica.ufpr.br [Universidade Federal do Parana, Departamento de Fisica (Brazil)

    2012-09-15

    We report on the interaction of vanadate nanoparticles, produced using the laser ablation in liquids synthesis, with cysteine in biological molecules. Cysteine is a very important amino acid present in most proteins, but also because cysteine and the tripeptide glutathione are the main antioxidant molecules in our body system. Detailed UV-Vis absorption spectra and dynamic light scattering measurements were done to investigate the detection of cysteine in large biological molecules. The intervalence band of the optical absorption spectra shows capability for quantitative cysteine sensing in the {mu}M range in biological macromolecules. Tests included cytoplasmic repetitive antigen and flagellar repetitive antigen proteins of the Trypanosoma cruzi protozoa, as well as the capsid p24 proteins from Human Immunodeficiency Virus type 1 and type 2. Detailed NMR measurements for hydrogen, carbon, and vanadium nuclei show that cysteine in contact with the vanadate looses hydrogen of the sulphydryl side chain, while the vanadate is reduced. The subsequent detachment of two deprotonated molecules to form cystine and the slow return to the vanadate complete the oxidation-reduction cycle. Therefore, the vanadate acts as a charge exchanging catalyst on cysteine to form cystine. The NMR results also indicate that the nanoparticles are not formed by the common orthorhombic V{sub 2}O{sub 5} form.

  17. Repair mechanisms inducible to the DNA in I.M.M.S. biological systems

    International Nuclear Information System (INIS)

    Guzman, J.; Arceo, C.; Cortinas, C.; Rosa, M.E. De la; Olvera, O.; Cruces, M.; Pimentel, E.

    1990-03-01

    Given the characteristics of the MMS and the relative antecedents to the repair mechanisms in eucariontes are sought to determine the effect of the MMS on the genetic material and their repair in Drosophila melanogaster. (Author)

  18. Elucidating the molecular mechanisms underlying cellular response to biophysical cues using synthetic biology approaches

    NARCIS (Netherlands)

    Denning, Denise; Roos, Wouter H

    2016-01-01

    The use of synthetic surfaces and materials to influence and study cell behavior has vastly progressed our understanding of the underlying molecular mechanisms involved in cellular response to physicochemical and biophysical cues. Reconstituting cytoskeletal proteins and interfacing them with a

  19. Mechanical aspects of developmental biology: perspectives On Growth and Form in the (post)-genomic age

    International Nuclear Information System (INIS)

    Hutson, M Shane; Ma Xiaoyan

    2008-01-01

    Simple experiments demonstrate that the development of an organism is both a genetic and a physical process. This statement is so obvious that it is seldom stated explicitly, and yet, there has been little progress toward integrating what should be complementary viewpoints. This paper focuses on the mechanical aspects of morphogenesis—highlighting those areas where mechanics and molecular genetics are converging toward a much-needed synthesis

  20. Microscale failure mechanisms leading to internal short circuit in Li-ion batteries under complex loading scenarios

    NARCIS (Netherlands)

    Sahraei, E.; Bosco, E.; Dixon, B.; Lai, B.

    2016-01-01

    One of the least understood mechanisms of Li-ion batteries is the development of internal short circuits under mechanical loads. In this study, a micro mechanical model is developed and subjected to various loading scenarios to understand the sequence of failure in the multi-layer, multi-material

  1. The complete genome sequence of Bacillus velezensis 9912D reveals its biocontrol mechanism as a novel commercial biological fungicide agent.

    Science.gov (United States)

    Pan, Hua-Qi; Li, Qing-Lian; Hu, Jiang-Chun

    2017-04-10

    A Bacillus sp. 9912 mutant, 9912D, was approved as a new biological fungicide agent by the Ministry of Agriculture of the People's Republic of China in 2016 owing to its excellent inhibitory effect on various plant pathogens and being environment-friendly. Here, we present the genome of 9912D with a circular chromosome having 4436 coding DNA sequences (CDSs), and a circular plasmid encoding 59 CDSs. This strain was finally designated as Bacillus velezensis based on phylogenomic analyses. Genome analysis revealed a total of 19 candidate gene clusters involved in secondary metabolite biosynthesis, including potential new type II lantibiotics. The absence of fengycin biosynthetic gene cluster is noteworthy. Our data offer insights into the genetic, biological and physiological characteristics of this strain and aid in deeper understanding of its biocontrol mechanism. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Systems biology derived source-sink mechanism of BMP gradient formation.

    Science.gov (United States)

    Zinski, Joseph; Bu, Ye; Wang, Xu; Dou, Wei; Umulis, David; Mullins, Mary C

    2017-08-09

    A morphogen gradient of Bone Morphogenetic Protein (BMP) signaling patterns the dorsoventral embryonic axis of vertebrates and invertebrates. The prevailing view in vertebrates for BMP gradient formation is through a counter-gradient of BMP antagonists, often along with ligand shuttling to generate peak signaling levels. To delineate the mechanism in zebrafish, we precisely quantified the BMP activity gradient in wild-type and mutant embryos and combined these data with a mathematical model-based computational screen to test hypotheses for gradient formation. Our analysis ruled out a BMP shuttling mechanism and a bmp transcriptionally-informed gradient mechanism. Surprisingly, rather than supporting a counter-gradient mechanism, our analyses support a fourth model, a source-sink mechanism, which relies on a restricted BMP antagonist distribution acting as a sink that drives BMP flux dorsally and gradient formation. We measured Bmp2 diffusion and found that it supports the source-sink model, suggesting a new mechanism to shape BMP gradients during development.

  3. Thermal optimum analyses and mechanical design of 10-kA, vapor-cooled power leads for SSC superconducting magnet tests at MTL

    International Nuclear Information System (INIS)

    Shu, Q.S.; Demko, J.; Dorman, R.; Finan, D.; Hatfield, D.; Syromyatnikov, I.; Zolotov, A.; Mazur, P.; Peterson, T.

    1992-08-01

    The spiral-fin, 10-kA, helium vapor-cooled power leads have been designed for Superconducting Super Collider superconducting magnet tests at the Magnet Test Laboratory. In order to thermally optimize the parameters of the power leads, the lead diameters-which minimize the Carnot work for several different lengths, two different fin geometries, and two RRR values of the lead materials-were determined. The cryogenic refrigeration and liquefaction loads for supporting the leads have also been calculated. The optimum operational condition with different currents is discussed. An improved mechanical design of the 10-kA power leads was undertaken, with careful consideration of the cryogenic and mechanical performance. In the design, a new thermal barrier device to reduce heat conduction from the vacuum and gas seal area was employed. Therefore, the electric insulation assembly, which isolates the ground potential parts of the lead from the high-power parts, was moved into a warm region in order to prevent vacuum and helium leakage in the 0-ring seals due to transient cold temperature. The instrumentation for testing the power leads is also discussed

  4. Increased extracellular and intracellular Ca{sup 2+} lead to adipocyte accumulation in bone marrow stromal cells by different mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Ryota, E-mail: hryota@juntendo.ac.jp [Department of Physiology, Juntendo University Faculty of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Katoh, Youichi, E-mail: katoyo@juntendo-urayasu.jp [Juntendo University Faculty of International Liberal Arts, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Department of Cardiology, Juntendo University Faculty of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Miyamoto, Yuki [Juntendo University Faculty of Health Care and Nursing, Takasu 2-5-1, Urayasu-shi, Chiba 279-0023 (Japan); Itoh, Seigo; Daida, Hiroyuki [Department of Cardiology, Juntendo University Faculty of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Nakazato, Yuji [Center for Environmental Research, Department of Cardiology, Juntendo University Faculty of Medicine Urayasu Hospital, Tomioka 2-1-1, Urayasu-shi, Chiba 279-0022 (Japan); Okada, Takao [Department of Physiology, Juntendo University Faculty of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan)

    2015-02-20

    Mesenchymal stem cells found in bone marrow stromal cells (BMSCs) are the common progenitors for both adipocyte and osteoblast. An increase in marrow adipogenesis is associated with age-related osteopenia and anemia. Both extracellular and intracellular Ca{sup 2+} ([Ca{sup 2+}]{sub o} and [Ca{sup 2+}]{sub i}) are versatile signaling molecules that are involved in the regulation of cell functions, including proliferation and differentiation. We have recently reported that upon treatment of BMSCs with insulin and dexamethasone, both high [Ca{sup 2+}]{sub o} and high [Ca{sup 2+}]{sub i} enhanced adipocyte accumulation, which suggested that increases in [Ca{sup 2+}]{sub o} caused by bone resorption may accelerate adipocyte accumulation in aging and diabetic patients. In this study, we used primary mouse BMSCs to investigate the mechanisms by which high [Ca{sup 2+}]{sub o} and high [Ca{sup 2+}]{sub i} may enhance adipocyte accumulation. In the process of adipocyte accumulation, two important keys are adipocyte differentiation and the proliferation of BMSCs, which have the potential to differentiate into adipocytes. Use of MTT assay and real-time RT-PCR revealed that high [Ca{sup 2+}]{sub i} (ionomycin)-dependent adipocyte accumulation is caused by enhanced proliferation of BMSCs but not enhanced differentiation into adipocytes. Using fura-2 fluorescence-based approaches, we showed that high [Ca{sup 2+}]{sub o} (addition of CaCl{sub 2}) leads to increases in [Ca{sup 2+}]{sub i}. Flow cytometric methods revealed that high [Ca{sup 2+}]{sub o} suppressed the phosphorylation of ERK independently of intracellular Ca{sup 2+}. The inhibition of ERK by U0126 and PD0325901 enhanced the differentiation of BMSCs into adipocytes. These data suggest that increased extracellular Ca{sup 2+} provides the differentiation of BMSCs into adipocytes by the suppression of ERK activity independently of increased intracellular Ca{sup 2+}, which results in BMSC proliferation. - Highlights:

  5. Mechanical-biological waste treatment and anaerobic processes. 59. information meeting, Neuwied, October 1999; Mechanisch-biologische Restabfallbehandlung und Anaerobverfahren. 59. Informationsgespraech in Neuwied im Oktober 1999

    Energy Technology Data Exchange (ETDEWEB)

    Hangen, H.O.; Euler, H.; Leonhardt, H.W. [comps.

    1999-10-01

    This proceedings volume discusses the specifications for and cost of mechanical-biological waste treatment, the optimisation of economic efficiency and pollutant emissons, the combination of mechanical-biological and thermal waste treatment processes, the value of mechanical-biological waste treatment, waste management concepts, process engineering and practical experience, and the eco-balance of the process. [German] Themen dieses Proceedingsbandes sind: Anforderungen und Kosten der mechanisch-biologischen Abfallbehandlung; Optimierung der Wirtschaftlichkeit und Emissionssituation; Kombination von mechanisch-biologischer und thermischer Muellbehandlung; Bewertung der mechanisch-biologischen Abfallbehandlung, Abfallwirtschaftskonzepte, Verfahrenstechnik und Betriebserfahrungen; Oekobilanz. (SR)

  6. THE RENIN-ANGIOTENSIN SYSTEM AND THE BIOLOGY OF SKELETAL MUSCLE: MECHANISMS OF MUSCLE WASTING IN CHRONIC DISEASE STATES.

    Science.gov (United States)

    Delafontaine, Patrice; Yoshida, Tadashi

    2016-01-01

    Sarcopenia and cachexia are muscle-wasting syndromes associated with aging and with many chronic diseases such as congestive heart failure, diabetes, cancer, chronic obstructive pulmonary disease, and renal failure. While mechanisms are complex, these conditions are often accompanied by elevated angiotensin II (Ang II). We found that Ang II infusion in rodents leads to skeletal muscle wasting via alterations in insulin-like growth factor-1 signaling, increased apoptosis, enhanced muscle protein breakdown via the ubiquitin-proteasome system, and decreased appetite resulting from downregulation of hypothalamic orexigenic neuropeptides orexin and neuropeptide Y. Furthermore, Ang II inhibits skeletal muscle stem cell proliferation, leading to lowered muscle regenerative capacity. Distinct stem cell Ang II receptor subtypes are critical for regulation of muscle regeneration. In ischemic mouse congestive heart failure model skeletal muscle wasting and attenuated muscle regeneration are Ang II dependent. These data suggest that the renin-angiotensin system plays a critical role in mechanisms underlying cachexia in chronic disease states.

  7. Is the internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? A systematic review.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Pellizzer, Eduardo Piza; da Silva, Emily Vivianne Freitas; Bonatto, Liliane da Rocha; dos Santos, Daniela Micheline

    2015-09-01

    This systematic review aimed to evaluate if the internal connection is more efficient than the external connection and its associated influencing factors. A specific question was formulated according to the Population, Intervention, Control, and Outcome (PICO): Is internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? An electronic search of the MEDLINE and the Web of Knowledge databases was performed for relevant studies published in English up to November 2013 by two independent reviewers. The keywords used in the search included a combination of "dental implant" and "internal connection" or "Morse connection" or "external connection." Selected studies were randomized clinical trials, prospective or retrospective studies, and in vitro studies with a clear aim of investigating the internal and/or external implant connection use. From an initial screening yield of 674 articles, 64 potentially relevant articles were selected after an evaluation of their titles and abstracts. Full texts of these articles were obtained with 29 articles fulfilling the inclusion criteria. Morse taper connection has the best sealing ability. Concerning crestal bone loss, internal connections presented better results than external connections. The limitation of the present study was the absence of randomized clinical trials that investigated if the internal connection was more efficient than the external connection. The external and internal connections have different mechanical, biological, and esthetical characteristics. Besides all systems that show proper success rates and effectiveness, crestal bone level maintenance is more important around internal connections than external connections. The Morse taper connection seems to be more efficient concerning biological aspects, allowing lower bacterial leakage and bone loss in single implants, including aesthetic regions. Additionally, this connection type can be successfully

  8. Influences of mechanical pre-treatment on the non-biological treatment of municipal wastewater by forward osmosis

    DEFF Research Database (Denmark)

    Hey, Tobias; Zarebska, Agata; Bajraktari, Niada

    2016-01-01

    municipal wastewater treatment without the biological treatment step, including the effects of different pre-treatment configurations, e.g., direct membrane filtration before forward osmosis. Forward osmosis was tested using raw wastewater and wastewater subjected to different types of mechanical pre-treatment......, e.g., microsieving and microfiltration permeation, as a potential technology for municipal wastewater treatment. Forward osmosis was performed using thin-film-composite, Aquaporin Inside(TM) and HTI membranes with NaCl as the draw solution. Both types of forward osmosis membranes were tested......-sized wastewater treatment plants....

  9. Study Under AC Stimulation on Excitement Properties of Weighted Small-World Biological Neural Networks with Side-Restrain Mechanism

    International Nuclear Information System (INIS)

    Yuan Wujie; Luo Xiaoshu; Jiang Pinqun

    2007-01-01

    In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under alternating current (AC) stimulation. The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli, such as refractory period and the brain neural excitement response induced by different intensities of noise and coupling. The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.

  10. Lead in the environment

    Science.gov (United States)

    Pattee, Oliver H.; Pain, Deborah J.; Hoffman, David J.; Rattner, Barnett A.; Burton, G. Allen; Cairns, John

    2003-01-01

    Anthropogenic uses of lead have probably altered its availability and environmental distribution more than any other toxic element. Consequently, lead concentrations in many living organisms may be approaching thresholds of toxicity for the adverse effects of lead. Such thresholds are difficult to define, as they vary with the chemical and physical form of lead, exposure regime, other elements present and also vary both within and between species. The technological capability to accurately quantify low lead concentrations has increased over the last decade, and physiological and behavioral effects have been measured in wildlife with tissue lead concentrations below those previously considered safe for humans.s.236 Consequently. lead criteria for the protection of wildlife and human health are frequently under review, and 'thresholds' of lead toxicity are being reconsidered. Proposed lead criteria for the protection of natural resources have been reviewed by Eisler. Uptake of lead by plants is limited by its generally low availability in soils and sediments, and toxicity may be limited by storage mechanisms and its apparently limited translocation within most plants. Lead does not generally accumulate within the foliar parts of plants, which limits its transfer to higher trophic levels. Although lead may concentrate in plant and animal tissues, no evidence of biomagnification exists. Acid deposition onto surface waters and soils with low buffering capacity may influence the availability of lead for uptake by plants and animals, and this may merit investigation at susceptible sites. The biological significance of chronic low-level lead exposure to wildlife is sometimes difficult to quantify. Animals living in urban environments or near point sources of lead emission are inevitably subject to greater exposure to lead and enhanced risk of lead poisoning. Increasingly strict controls on lead emissions in many countries have reduced exposure to lead from some sources

  11. Genotoxic Pyrrolizidine Alkaloids — Mechanisms Leading to DNA Adduct Formation and Tumorigenicity

    OpenAIRE

    Ming W. Chou; Ge Lin; Qingsu Xia; Peter P. Fu

    2002-01-01

    Abstract: Plants that contain pyrrolizidine alkaloids are widely distributed in the world. Although pyrrolizidine alkaloids have been shown to be genotoxic and tumorigenic in experimental animals, the mechanisms of actions have not been fully understood. The results of our recent mechanistic studies suggest that pyrrolizidine alkaloids induce tumors via a genotoxic mechanism mediated by 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5Hpyrrolizine (DHP)-derived DNA adduct formation. This mechanism may ...

  12. Mechanical property and biological performance of electrospun silk fibroin-polycaprolactone scaffolds with aligned fibers.

    Science.gov (United States)

    Yuan, Han; Shi, Hongfei; Qiu, Xushen; Chen, Yixin

    2016-01-01

    The mechanical strength, biocompatibility, and sterilizability of silk fibroin allow it to be a possible candidate as a natural bone regenerate material. To improve mechanical character and reinforce the cell movement induction, silk fibroin (SF)-polycaprolactone (PCL) alloy was fabricated by electrospinning techniques with a rotating collector to form aligned fibrous scaffolds and random-oriented scaffolds. The scanning electron microscope image of the scaffold and the mechanical properties of the scaffold were investigated by tensile mechanical tests, which were compared to random-oriented scaffolds. Furthermore, mesenchymal stem cells were planted on these scaffolds to investigate the biocompatibility, elongation, and cell movement in situ. Scanning electron microscopy shows that 91% fibers on the aligned fibroin scaffold were distributed between the dominant direction ±10°. With an ideal support for stem cell proliferation in vitro, the aligned fibrous scaffold induces cell elongation at a length of 236.46 ± 82 μm and distribution along the dominant fiber direction with a cell alignment angle at 6.57° ± 4.45°. Compared with random-oriented scaffolds made by artificial materials, aligned SF-PCL scaffolds could provide a moderate mesenchymal stem cell engraftment interface and speed up early stage cell movement toward the bone defect.

  13. A Review of Biological Communication Mechanisms Applicable to Small Autonomous Systems

    Science.gov (United States)

    2010-09-01

    katydids, grasshoppers, beetles, moths, butterflies , ants, caterpillars, beetle larvae Hitting the ground Band-winged grasshoppers, cockroaches... butterflies and moths (Lepidoptera and Noctuidae). The Agaristid moth (e.g., Hecatesia exultans and Hecatesia thyridion) has castanet-like...Insects. The Ohio J. of Science 1957, 57 (2), 101. Bailey, W. J. The Mechanics of Stridulation in Bush Crickets (Tettigonioidea, Orthoptera): I

  14. Scale relativity theory and integrative systems biology: 2. Macroscopic quantum-type mechanics.

    Science.gov (United States)

    Nottale, Laurent; Auffray, Charles

    2008-05-01

    In these two companion papers, we provide an overview and a brief history of the multiple roots, current developments and recent advances of integrative systems biology and identify multiscale integration as its grand challenge. Then we introduce the fundamental principles and the successive steps that have been followed in the construction of the scale relativity theory, which aims at describing the effects of a non-differentiable and fractal (i.e., explicitly scale dependent) geometry of space-time. The first paper of this series was devoted, in this new framework, to the construction from first principles of scale laws of increasing complexity, and to the discussion of some tentative applications of these laws to biological systems. In this second review and perspective paper, we describe the effects induced by the internal fractal structures of trajectories on motion in standard space. Their main consequence is the transformation of classical dynamics into a generalized, quantum-like self-organized dynamics. A Schrödinger-type equation is derived as an integral of the geodesic equation in a fractal space. We then indicate how gauge fields can be constructed from a geometric re-interpretation of gauge transformations as scale transformations in fractal space-time. Finally, we introduce a new tentative development of the theory, in which quantum laws would hold also in scale space, introducing complexergy as a measure of organizational complexity. Initial possible applications of this extended framework to the processes of morphogenesis and the emergence of prokaryotic and eukaryotic cellular structures are discussed. Having founded elements of the evolutionary, developmental, biochemical and cellular theories on the first principles of scale relativity theory, we introduce proposals for the construction of an integrative theory of life and for the design and implementation of novel macroscopic quantum-type experiments and devices, and discuss their potential

  15. Networks In Real Space: Characteristics and Analysis for Biology and Mechanics

    Science.gov (United States)

    Modes, Carl; Magnasco, Marcelo; Katifori, Eleni

    Functional networks embedded in physical space play a crucial role in countless biological and physical systems, from the efficient dissemination of oxygen, blood sugars, and hormonal signals in vascular systems to the complex relaying of informational signals in the brain to the distribution of stress and strain in architecture or static sand piles. Unlike their more-studied abstract cousins, such as the hyperlinked internet, social networks, or economic and financial connections, these networks are both constrained by and intimately connected to the physicality of their real, embedding space. We report on the results of new computational and analytic approaches tailored to these physical networks with particular implications and insights for mammalian organ vasculature.

  16. Perceptron-like computation based on biologically-inspired neurons with heterosynaptic mechanisms

    Science.gov (United States)

    Kaluza, Pablo; Urdapilleta, Eugenio

    2014-10-01

    Perceptrons are one of the fundamental paradigms in artificial neural networks and a key processing scheme in supervised classification tasks. However, the algorithm they provide is given in terms of unrealistically simple processing units and connections and therefore, its implementation in real neural networks is hard to be fulfilled. In this work, we present a neural circuit able to perform perceptron's computation based on realistic models of neurons and synapses. The model uses Wang-Buzsáki neurons with coupling provided by axodendritic and axoaxonic synapses (heterosynapsis). The main characteristics of the feedforward perceptron operation are conserved, which allows to combine both approaches: whereas the classical artificial system can be used to learn a particular problem, its solution can be directly implemented in this neural circuit. As a result, we propose a biologically-inspired system able to work appropriately in a wide range of frequencies and system parameters, while keeping robust to noise and error.

  17. Ventilation versus biology: What is the controlling mechanism of nitrous oxide distribution in the North Atlantic?

    Science.gov (United States)

    Paz, Mercedes; García-Ibáñez, Maribel I.; Steinfeldt, Reiner; Ríos, Aida F.; Pérez, Fiz F.

    2017-04-01

    The extent to which water mass mixing and ocean ventilation contribute to nitrous oxide (N2O) distribution at the scale of oceanic basins is poorly constrained. We used novel N2O and chlorofluorocarbon measurements along with multiparameter water mass analysis to evaluate the impact of water mass mixing and Atlantic Meridional Overturning Circulation (AMOC) on N2O distribution along the Observatoire de la variabilité interannuelle et décennale en Atlantique Nord (OVIDE) section, extending from Portugal to Greenland. The biological N2O production has a stronger impact on the observed N2O concentrations in the water masses traveling northward in the upper limb of the AMOC than those in recently ventilated cold water masses in the lower limb, where N2O concentrations reflect the colder temperatures. The high N2O tongue, with concentrations as high as 16 nmol kg-1, propagates above the isopycnal surface delimiting the upper and lower AMOC limbs, which extends from the eastern North Atlantic Basin to the Iceland Basin and coincides with the maximum N2O production rates. Water mixing and basin-scale remineralization account for 72% of variation in the observed distribution of N2O. The mixing-corrected stoichiometric ratio N2O:O2 for the North Atlantic Basin of 0.06 nmol/μmol is in agreement with ratios of N2O:O2 for local N2O anomalies, suggesting than up to 28% of N2O production occurs in the temperate and subpolar Atlantic, an overlooked region for N2O cycling. Overall, our results highlight the importance of taking into account mixing, O2 undersaturation when water masses are formed and the increasing atmospheric N2O concentrations when parameterizing N2O:O2 and biological N2O production in the global oceans.

  18. The radioinduced membranes injuries as biological dose indicators: mechanisms of studies and practical applications

    International Nuclear Information System (INIS)

    Vincent-Genod, Lucie

    2001-10-01

    After an accidental overexposure, the assessment of the received dose in biological dosimetry is performed by a method based on the effects of irradiation on the DNA molecule. But this technique shows some limitations; therefore we tried to find new bio-sensors of radiation exposure. We have pointed out that membrane is a critical target of ionising radiation after an in vitro and in vivo overexposure. In vitro, these modifications were involved in the radio-induced apoptotic pathway. The measure of membrane fluidity allowed us to obtain an overall view of cellular membrane. Moreover, in vivo, by changing the lipid nutritional status of animals, our results displayed the important role played by membrane lipid composition in radio-induced membrane alterations. Besides, membrane effects were adjusted by the extracellular physiological control, and in particular by the damages on membrane fatty acid pattern. Finally, we have tested the use of membrane fluidity index as a bio-sensor of radiation exposure on in vivo models and blood samples from medical total body irradiated patients. The results achieved on animal models suggested that the membrane fluidity index was a bio-sensor of radiation exposure. Nevertheless, the observations realised on patients highlight that the effect of the first dose fraction of the radiotherapy treatment had some difficulties to be noticed. Indeed, the combined treatment: chemotherapy and radiotherapy disturbed the membrane fluidity index measures. To conclude, whereas this parameter was not a bio-sensor of irradiation exposure usable in biological dosimetry, it may allow us to assess the radio-induced damages and their cellular but also tissue impacts. (author)

  19. Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Cimpean, Anisoara [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Vasilescu, Ecaterina; Drob, Paula [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cinca, Ion, E-mail: ion_cinca@hotmail.com [Faculty of Material Science and Engineering, Politehnica University, Spl. Independentei 313, 060042 Bucharest (Romania); Vasilescu, Cora; Anastasescu, Mihai [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, Valentina [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Drob, Silviu Iulian [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2014-05-01

    A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances.

  20. Fabrication method, structure, mechanical, and biological properties of decellularized extracellular matrix for replacement of wide bone tissue defects.

    Science.gov (United States)

    Anisimova, N Y; Kiselevsky, M V; Sukhorukova, I V; Shvindina, N V; Shtansky, D V

    2015-09-01

    The present paper was focused on the development of a new method of decellularized extracellular matrix (DECM) fabrication via a chemical treatment of a native bone tissue. Particular attention was paid to the influence of chemical treatment on the mechanical properties of native bones, sterility, and biological performance in vivo using the syngeneic heterotopic and orthotopic implantation models. The obtained data indicated that after a chemical decellularization treatment in 4% aqueous sodium chlorite, no noticeable signs of the erosion of compact cortical bone surface or destruction of trabeculae of spongy bone in spinal channel were observed. The histological studies showed that the chemical treatment resulted in the decellularization of both bone and cartilage tissues. The DECM samples demonstrated no signs of chemical and biological degradation in vivo. Thorough structural characterization revealed that after decellularization, the mineral frame retained its integrity with the organic phase; however clotting and destruction of organic molecules and fibers were observed. FTIR studies revealed several structural changes associated with the destruction of organic molecules, although all organic components typical of intact bone were preserved. The decellularization-induced structural changes in the collagen constituent resulted changed the deformation under compression mechanism: from the major fracture by crack propagation throughout the sample to the predominantly brittle fracture. Although the mechanical properties of radius bones subjected to decellularization were observed to degrade, the mechanical properties of ulna bones in compression and humerus bones in bending remained unchanged. The compressive strength of both the intact and decellularized ulna bones was 125-130 MPa and the flexural strength of humerus bones was 156 and 145 MPa for the intact and decellularized samples, respectively. These results open new avenues for the use of DECM samples as

  1. Suitability of a PLCL fibrous scaffold for soft tissue engineering applications: A combined biological and mechanical characterisation.

    Science.gov (United States)

    Laurent, Cédric P; Vaquette, Cédryck; Liu, Xing; Schmitt, Jean-François; Rahouadj, Rachid

    2018-04-01

    Poly(lactide-co-ε-caprolactone) (PLCL) has been reported to be a good candidate for tissue engineering because of its good biocompatibility. Particularly, a braided PLCL scaffold (PLL/PCL ratio = 85/15) has been recently designed and partially validated for ligament tissue engineering. In the present study, we assessed the in vivo biocompatibility of acellular and cellularised scaffolds in a rat model. We then determined its in vitro biocompatibility using stem cells issued from both bone marrow and Wharton Jelly. From a biological point of view, the scaffold was shown to be suitable for tissue engineering in all these cases. Secondly, while the initial mechanical properties of this scaffold have been previously reported to be adapted to load-bearing applications, we studied the evolution in time of the mechanical properties of PLCL fibres due to hydrolytic degradation. Results for isolated PLCL fibres were extrapolated to the fibrous scaffold using a previously developed numerical model. It was shown that no accumulation of plastic strain was to be expected for a load-bearing application such as anterior cruciate ligament tissue engineering. However, PLCL fibres exhibited a non-expected brittle behaviour after two months. This may involve a potential risk of premature failure of the scaffold, unless tissue growth compensates this change in mechanical properties. This combined study emphasises the need to characterise the properties of biomaterials in a pluridisciplinary approach, since biological and mechanical characterisations led in this case to different conclusions concerning the suitability of this scaffold for load-bearing applications.

  2. Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

    International Nuclear Information System (INIS)

    Cimpean, Anisoara; Vasilescu, Ecaterina; Drob, Paula; Cinca, Ion; Vasilescu, Cora; Anastasescu, Mihai; Mitran, Valentina; Drob, Silviu Iulian

    2014-01-01

    A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances

  3. Lead transport in intra-oceanic subduction zones: 2D geochemical-thermo-mechanical modeling of isotopic signatures

    NARCIS (Netherlands)

    Baitsch-Ghirardello, B.; Stracke, A.; Connolly, J.A.D.; Nikolaeva, K.M.; Gerya, T.V.

    2014-01-01

    Understanding the physical-chemical mechanisms and pathways of geochemical transport in subduction zones remains a long-standing goal of subduction-related research. In this study, we perform fully coupled geochemical-thermo-mechanical (GcTM) numerical simulations to investigate Pb isotopic

  4. Biology of Acinetobacter baumannii: Pathogenesis, Antibiotic Resistance Mechanisms, and Prospective Treatment Options

    Science.gov (United States)

    Lee, Chang-Ro; Lee, Jung Hun; Park, Moonhee; Park, Kwang Seung; Bae, Il Kwon; Kim, Young Bae; Cha, Chang-Jun; Jeong, Byeong Chul; Lee, Sang Hee

    2017-01-01

    Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A. baumannii pathogenesis, including porins, capsular polysaccharides, lipopolysaccharides, phospholipases, outer membrane vesicles, metal acquisition systems, and protein secretion systems. Mechanisms of antibiotic resistance of this organism, including acquirement of β-lactamases, up-regulation of multidrug efflux pumps, modification of aminoglycosides, permeability defects, and alteration of target sites, are also discussed. Lastly, novel prospective treatment options for infections caused by multi-drug resistant A. baumannii are summarized. PMID:28348979

  5. Biological Communities in Desert Varnish and Potential Implications for Varnish Formation Mechanisms

    Science.gov (United States)

    Lang-Yona, Naama; Maier, Stefanie; Macholdt, Dorothea; Rodriguez-Caballero, Emilio; Müller-Germann, Isabell; Yordanova, Petya; Jochum, Klaus-Peter; Andreae, Meinrat O.; Pöschl, Ulrich; Weber, Bettina; Fröhlich-Nowoisky, Janine

    2017-04-01

    Desert varnishes are thin, orange to black coatings found on rocks in arid and semi-arid environments on Earth. The formation mechanisms of rock varnish are still under debate and the involvement of microorganisms in this process remains unclear. In this work we aimed to identify the microbial community occurring in rock varnish to potentially gain insights into the varnish formation mechanism. For this purpose, rocks coated with desert varnish were collected from the Anza-Borrego Desert, California, USA, as well as soils from underneath the rocks. DNA from both varnish coatings and soil samples was extracted and subsequently used for metagenomic analysis, as well as for q-PCR analyses for specific species quantification. The element composition of the varnish coatings was analyzed and compared to the soil samples. Rock varnish shows similar depleted elements, compared to soil, but Mn and Pb are 50-60 times enriched compared to the soil samples, and about 100 times enriched compared to the upper continental crust. Our genomic analyses suggest unique populations and different protein functional groups occurring in the varnish compared to soil samples. We discuss these differences and try to shed light on the mechanism of Mn oxyhydroxide production in desert varnish formation.

  6. Experimental and modelling studies on a laboratory scale anaerobic bioreactor treating mechanically biologically treated municipal solid waste.

    Science.gov (United States)

    Lakshmikanthan, P; Sughosh, P; White, James; Sivakumar Babu, G L

    2017-07-01

    The performance of an anaerobic bioreactor in treating mechanically biologically treated municipal solid waste was investigated using experimental and modelling techniques. The key parameters measured during the experimental test period included the gas yield, leachate generation and settlement under applied load. Modelling of the anaerobic bioreactor was carried out using the University of Southampton landfill degradation and transport model. The model was used to simulate the actual gas production and settlement. A sensitivity analysis showed that the most influential model parameters are the monod growth rate and moisture. In this case, pH had no effect on the total gas production and waste settlement, and only a small variation in the gas production was observed when the heat transfer coefficient of waste was varied from 20 to 100 kJ/(m d K) -1 . The anaerobic bioreactor contained 1.9 kg (dry) of mechanically biologically treated waste producing 10 L of landfill gas over 125 days.

  7. Recent advances in the understanding of brown spider venoms: From the biology of spiders to the molecular mechanisms of toxins.

    Science.gov (United States)

    Gremski, Luiza Helena; Trevisan-Silva, Dilza; Ferrer, Valéria Pereira; Matsubara, Fernando Hitomi; Meissner, Gabriel Otto; Wille, Ana Carolina Martins; Vuitika, Larissa; Dias-Lopes, Camila; Ullah, Anwar; de Moraes, Fábio Rogério; Chávez-Olórtegui, Carlos; Barbaro, Katia Cristina; Murakami, Mario Tyago; Arni, Raghuvir Krishnaswamy; Senff-Ribeiro, Andrea; Chaim, Olga Meiri; Veiga, Silvio Sanches

    2014-06-01

    The Loxosceles genus spiders (the brown spiders) are encountered in all the continents, and the clinical manifestations following spider bites include skin necrosis with gravitational lesion spreading and occasional systemic manifestations, such as intravascular hemolysis, thrombocytopenia and acute renal failure. Brown spider venoms are complex mixtures of toxins especially enriched in three molecular families: the phospholipases D, astacin-like metalloproteases and Inhibitor Cystine Knot (ICK) peptides. Other toxins with low level of expression also present in the venom include the serine proteases, serine protease inhibitors, hyaluronidases, allergen factors and translationally controlled tumor protein (TCTP). The mechanisms by which the Loxosceles venoms act and exert their noxious effects are not fully understood. Except for the brown spider venom phospholipase D, which causes dermonecrosis, hemolysis, thrombocytopenia and renal failure, the pathological activities of the other venom toxins remain unclear. The objective of the present review is to provide insights into the brown spider venoms and loxoscelism based on recent results. These insights include the biology of brown spiders, the clinical features of loxoscelism and the diagnosis and therapy of brown spider bites. Regarding the brown spider venom, this review includes a description of the novel toxins revealed by molecular biology and proteomics techniques, the data regarding three-dimensional toxin structures, and the mechanism of action of these molecules. Finally, the biotechnological applications of the venom components, especially for those toxins reported as recombinant molecules, and the challenges for future study are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Learning biology through connecting mathematics to scientific mechanisms: Student outcomes and teacher supports

    Science.gov (United States)

    Schuchardt, Anita

    Integrating mathematics into science classrooms has been part of the conversation in science education for a long time. However, studies on student learning after incorporating mathematics in to the science classroom have shown mixed results. Understanding the mixed effects of including mathematics in science has been hindered by a historical focus on characteristics of integration tangential to student learning (e.g., shared elements, extent of integration). A new framework is presented emphasizing the epistemic role of mathematics in science. An epistemic role of mathematics missing from the current literature is identified: use of mathematics to represent scientific mechanisms, Mechanism Connected Mathematics (MCM). Building on prior theoretical work, it is proposed that having students develop mathematical equations that represent scientific mechanisms could elevate their conceptual understanding and quantitative problem solving. Following design and implementation of an MCM unit in inheritance, a large-scale quantitative analysis of pre and post implementation test results showed MCM students, compared to traditionally instructed students) had significantly greater gains in conceptual understanding of mathematically modeled scientific mechanisms, and their ability to solve complex quantitative problems. To gain insight into the mechanism behind the gain in quantitative problem solving, a small-scale qualitative study was conducted of two contrasting groups: 1) within-MCM instruction: competent versus struggling problem solvers, and 2) within-competent problem solvers: MCM instructed versus traditionally instructed. Competent MCM students tended to connect their mathematical inscriptions to the scientific phenomenon and to switch between mathematical and scientifically productive approaches during problem solving in potentially productive ways. The other two groups did not. To address concerns about teacher capacity presenting barriers to scalability of MCM

  9. Mechanism of Action for Anti-radiation Vaccine in Reducing the Biological Impact of High-dose Gamma Irradiation

    Science.gov (United States)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    2007-01-01

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  10. Biological cell as a soft magnetoelectric material: Elucidating the physical mechanisms underpinning the detection of magnetic fields by animals

    Science.gov (United States)

    Krichen, S.; Liu, L.; Sharma, P.

    2017-10-01

    Sharks, birds, bats, turtles, and many other animals can detect magnetic fields. Aside from using this remarkable ability to exploit the terrestrial magnetic field map to sense direction, a subset is also able to implement a version of the so-called geophysical positioning system. How do these animals detect magnetic fields? The answer to this rather deceptively simple question has proven to be quite elusive. The currently prevalent theories, while providing interesting insights, fall short of explaining several aspects of magnetoreception. For example, minute magnetic particles have been detected in magnetically sensitive animals. However, how is the detected magnetic field converted into electrical signals given any lack of experimental evidence for relevant electroreceptors? In principle, a magnetoelectric material is capable of converting magnetic signals into electricity (and vice versa). This property, however, is rare and restricted to a rather small set of exotic hard crystalline materials. Indeed, such elements have never been detected in the animals studied so far. In this work we quantitatively outline the conditions under which a biological cell may detect a magnetic field and convert it into electrical signals detectable by biological cells. Specifically, we prove the existence of an overlooked strain-mediated mechanism and show that most biological cells can act as nontrivial magnetoelectric materials provided that the magnetic permeability constant is only slightly more than that of a vacuum. The enhanced magnetic permeability is easily achieved by small amounts of magnetic particles that have been experimentally detected in magnetosensitive animals. Our proposed mechanism appears to explain most of the experimental observations related to the physical basis of magnetoreception.

  11. Mechanism of action for anti-radiation vaccine in reducing the biological impact of high-dose gamma irradiation

    Science.gov (United States)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after high-dose gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naïve animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which they mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  12. Review of low dose-rate epidemiological studies and biological mechanisms of dose-rate effects on radiation induced carcinogenesis

    International Nuclear Information System (INIS)

    Iwasaki, Toshiyasu; Otsuka, Kensuke; Yoshida, Kazuo

    2015-01-01

    Radiation protection system adopts the linear non-threshold model with using dose and dose-rate effectiveness factor (DDREF). The dose-rate range where DDREF is applied is below 100 mGy per hour, and it is regarded that there are no dose-rate effects at very low dose rate, less than of the order of 10 mGy per year, even from the biological risk evaluation model based on cellular and molecular level mechanisms for maintenance of genetic integrity. Among low dose-rate epidemiological studies, studies of residents in high natural background areas showed no increase of cancer risks at less than about 10 mGy per year. On the other hand, some studies include a study of the Techa River cohort suggested the increase of cancer risks to the similar degree of Atomic bomb survivor data. The difference of those results was supposed due to the difference of dose rate. In 2014, International Commission on Radiological Protection opened a draft report on stem cell biology for public consultations. The report proposed a hypothesis based on the new idea of stem cell competition as a tissue level quality control mechanism, and suggested that it could explain the dose-rate effects around a few milligray per year. To verify this hypothesis, it would be needed to clarify the existence and the lowest dose of radiation-induced stem cell competition, and to elucidate the rate of stem cell turnover and radiation effects on it. As for the turnover, replenishment of damaged stem cells would be the important biological process. It would be meaningful to collect the information to show the difference of dose rates where the competition and the replenishment would be the predominant processes. (author)

  13. Study on regeneration effect and mechanism of high-frequency ultrasound on biological activated carbon.

    Science.gov (United States)

    Sun, Zhehao; Liu, Cheng; Cao, Zhen; Chen, Wei

    2018-06-01

    High frequency ultrasonic radiation technology was developed as a novel and efficient means of regenerating spent biological activated carbon (BAC) used in drinking water treatment plants (DWTPs). The results of this study indicated that high frequency ultrasonic treatment could recover the spent BAC, to some extent, with the following optimal conditions: a frequency of 400 kHz, sonication power of 60 W, water temperature of 30 °C, and sonication time of 6 min. Under the above conditions, the iodine value increased from 300 mg/g to 409 mg/g, the volume of total pores and micropores increased from 0.2600 cm 3 /g and 0.1779 cm 3 /g to 0.3560 cm 3 /g and 0.2662 cm 3 /g, respectively; the specific surface area of micropores and the mean pore diameter expanded from 361.15 m 2 /g and 2.0975 nm to 449.92 m 2 /g and 2.1268 nm, respectively. The biological activity increased from 0.0297 mgO 2 /gC·h to 0.0521 mgO 2 /gC·h, while the biomass decreased from 203 nmolP/gC to 180 nmolP/gC. The results of high throughput 16S rRNA gene amplicon sequencing showed that microorganisms such as Clostridia and Nitrospira were markedly decreased due to high frequency ultrasound. The method used in this study caused the inhibition of certain carbon-attached microbials resulting in a negative effect on the removal rate of ammonia-N during the initial stage of the long-term reuse operation. The removal of UV254 and atrazine were restored from 8.1% and 55% to 21% and 76%, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Investigation of the effect of mechanical pressure on the performance of negative lead accumulator electrodes during partial state of charge operation

    Czech Academy of Sciences Publication Activity Database

    Bača, P.; Micka, Karel; Křivík, P.; Tonar, K.; Tošer, P.

    2012-01-01

    Roč. 207, JUN 1 2012 (2012), s. 37-44 ISSN 0378-7753 Institutional research plan: CEZ:AV0Z40400503 Keywords : Lead battery electrodes * Doping with carbon or titanium dioxide * Effect of mechanical pressure Subject RIV: CG - Electrochemistry Impact factor: 4.675, year: 2012

  15. System in biology leading to cell pathology: stable protein-protein interactions after covalent modifications by small molecules or in transgenic cells.

    Science.gov (United States)

    Malina, Halina Z

    2011-01-19

    The physiological processes in the cell are regulated by reversible, electrostatic protein-protein interactions. Apoptosis is such a regulated process, which is critically important in tissue homeostasis and development and leads to complete disintegration of the cell. Pathological apoptosis, a process similar to apoptosis, is associated with aging and infection. The current study shows that pathological apoptosis is a process caused by the covalent interactions between the signaling proteins, and a characteristic of this pathological network is the covalent binding of calmodulin to regulatory sequences. Small molecules able to bind covalently to the amino group of lysine, histidine, arginine, or glutamine modify the regulatory sequences of the proteins. The present study analyzed the interaction of calmodulin with the BH3 sequence of Bax, and the calmodulin-binding sequence of myristoylated alanine-rich C-kinase substrate in the presence of xanthurenic acid in primary retinal epithelium cell cultures and murine epithelial fibroblast cell lines transformed with SV40 (wild type [WT], Bid knockout [Bid-/-], and Bax-/-/Bak-/- double knockout [DKO]). Cell death was observed to be associated with the covalent binding of calmodulin, in parallel, to the regulatory sequences of proteins. Xanthurenic acid is known to activate caspase-3 in primary cell cultures, and the results showed that this activation is also observed in WT and Bid-/- cells, but not in DKO cells. However, DKO cells were not protected against death, but high rates of cell death occurred by detachment. The results showed that small molecules modify the basic amino acids in the regulatory sequences of proteins leading to covalent interactions between the modified sequences (e.g., calmodulin to calmodulin-binding sites). The formation of these polymers (aggregates) leads to an unregulated and, consequently, pathological protein network. The results suggest a mechanism for the involvement of small molecules

  16. Omega-3 Fatty Acids and Depression: Scientific Evidence and Biological Mechanisms

    Directory of Open Access Journals (Sweden)

    Giuseppe Grosso

    2014-01-01

    Full Text Available The changing of omega-6/omega-3 polyunsaturated fatty acids (PUFA in the food supply of Western societies occurred over the last 150 years is thought to promote the pathogenesis of many inflammatory-related diseases, including depressive disorders. Several epidemiological studies reported a significant inverse correlation between intake of oily fish and depression or bipolar disorders. Studies conducted specifically on the association between omega-3 intake and depression reported contrasting results, suggesting that the preventive role of omega-3 PUFA may depend also on other factors, such as overall diet quality and the social environment. Accordingly, tertiary prevention with omega-3 PUFA supplement in depressed patients has reached greater effectiveness during the last recent years, although definitive statements on their use in depression therapy cannot be yet freely asserted. Among the biological properties of omega-3 PUFA, their anti-inflammatory effects and their important role on the structural changing of the brain should be taken into account to better understand the possible pathway through which they can be effective both in preventing or treating depression. However, the problem of how to correct the inadequate supply of omega-3 PUFA in the Westernized countries’ diet is a priority in order to set food and health policies and also dietary recommendations for individuals and population groups.

  17. Single- and double-row repair for rotator cuff tears - biology and mechanics.

    Science.gov (United States)

    Papalia, Rocco; Franceschi, Francesco; Vasta, Sebastiano; Zampogna, Biagio; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    We critically review the existing studies comparing the features of single- and double-row repair, and discuss suggestions about the surgical indications for the two repair techniques. All currently available studies comparing the biomechanical, clinical and the biological features of single and double row. Biomechanically, the double-row repair has greater performances in terms of higher initial fixation strength, greater footprint coverage, improved contact area and pressure, decreased gap formation, and higher load to failure. Results of clinical studies demonstrate no significantly better outcomes for double-row compared to single-row repair. Better results are achieved by double-row repair for larger lesions (tear size 2.5-3.5 cm). Considering the lack of statistically significant differences between the two techniques and that the double row is a high cost and a high surgical skill-dependent technique, we suggest using the double-row technique only in strictly selected patients. Copyright © 2012 S. Karger AG, Basel.

  18. Mechanical properties of crossed-lamellar structures in biological shells: A review.

    Science.gov (United States)

    Li, X W; Ji, H M; Yang, W; Zhang, G P; Chen, D L

    2017-10-01

    The self-fabrication of materials in nature offers an alternate and powerful solution towards the grand challenge of designing advanced structural materials, where strength and toughness are always mutually exclusive. Crossed-lamellar structures are the most common microstructures in mollusks that are composed of aragonites and a small amount of organic materials. Such a distinctive composite structure has a fracture toughness being much higher than that of pure carbonate mineral. These structures exhibiting complex hierarchical microarchitectures that span several sub-level lamellae from microscale down to nanoscale, can be grouped into two types, i.e., platelet-like and fiber-like crossed-lamellar structures based on the shapes of basic building blocks. It has been demonstrated that these structures have a great potential to strengthen themselves during deformation. The observed underlying toughening mechanisms include microcracking, channel cracking, interlocking, uncracked-ligament bridging, aragonite fiber bridging, crack deflection and zig-zag, etc., which play vital roles in enhancing the fracture resistance of shells with the crossed-lamellar structures. The exploration and utilization of these important toughening mechanisms have attracted keen interests of materials scientists since they pave the way for the development of bio-inspired advanced composite materials for load-bearing structural applications. This article is aimed to review the characteristics of hierarchical structures and the mechanical properties of two kinds of crossed-lamellar structures, and further summarize the latest advances and biomimetic applications based on the unique crossed-lamellar structures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Genotoxic Pyrrolizidine Alkaloids — Mechanisms Leading to DNA Adduct Formation and Tumorigenicity

    Directory of Open Access Journals (Sweden)

    Ming W. Chou

    2002-09-01

    Full Text Available Abstract: Plants that contain pyrrolizidine alkaloids are widely distributed in the world. Although pyrrolizidine alkaloids have been shown to be genotoxic and tumorigenic in experimental animals, the mechanisms of actions have not been fully understood. The results of our recent mechanistic studies suggest that pyrrolizidine alkaloids induce tumors via a genotoxic mechanism mediated by 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5Hpyrrolizine (DHP-derived DNA adduct formation. This mechanism may be general to most carcinogenic pyrrolizidine alkaloids, including the retronecine-, heliotridine-, and otonecinetype pyrrolizidine alkaloids. It is hypothesized that these DHP-derived DNA adducts are potential biomarkers of pyrrolizidine alkaloid tumorigenicity. The mechanisms that involve the formation of DNA cross-linking and endogenous DNA adducts are also discussed.

  20. The environmental agreement may lead to large losses for the oil producers. The Kyoto mechanisms are very important to Norway

    International Nuclear Information System (INIS)

    1999-01-01

    The article presents an economic model study of the implications of an climatic agreement. Two main scenarios are presented: 1) The Kyoto protocol is extended to 2020. 2) All counties ratify a climatic agreement. The conclusions are that the Kyoto protocol may have great effects on the oil and gas markets and large economic consequences for Norway. It is therefore mandatory to extensively use the Kyoto mechanisms such as trade with quotas, common implementation and the green development mechanism

  1. Mechanical Characterisation and Biomechanical and Biological Behaviours of Ti-Zr Binary-Alloy Dental Implants

    Directory of Open Access Journals (Sweden)

    Aritza Brizuela-Velasco

    2017-01-01

    Full Text Available The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxolid© implants (Straumann, Basel, Switzerland via ultrasound. Their biomechanical behaviour was described via finite element analysis. Their osseointegration capacity was compared via an in vivo study performed on 12 adult rabbits. Young’s modulus of the Roxolid© implant was around 103 GPa, and the Poisson coefficient was around 0.33. There were no significant differences in terms of Von Mises stress values at the implant and bone level between both alloys. Regarding deformation, the highest value was observed for Ti-15Zr implant, and the lowest value was observed for the cortical bone surrounding TAV implant, with no deformation differences at the bone level between both alloys. Histological analysis of the implants inserted in rabbits demonstrated higher BIC percentage for Ti-15Zr implants at 3 and 6 weeks. Ti-15Zr alloy showed elastic properties and biomechanical behaviours similar to TAV alloy, although Ti-15Zr implant had a greater BIC percentage after 3 and 6 weeks of osseointegration.

  2. Functionalization of titanium with chitosan via silanation: evaluation of biological and mechanical performances.

    Directory of Open Access Journals (Sweden)

    Pauline Renoud

    Full Text Available Complications in dentistry and orthopaedic surgery are mainly induced by peri-implant bacterial infections and current implant devices do not prevent such infections. The coating of antibacterial molecules such as chitosan on its surface would give the implant bioactive properties. The major challenge of this type of coating is the attachment of chitosan to a metal substrate. In this study, we propose to investigate the functionalization of titanium with chitosan via a silanation. Firstly, the surface chemistry and mechanical properties of such coating were evaluated. We also verified if the coated chitosan retained its biocompatibility with the peri-implant cells, as well as its antibacterial properties. FTIR and Tof-SIMS analyses confirmed the presence of chitosan on the titanium surface. This coating showed great scratch resistance and was strongly adhesive to the substrate. These mechanical properties were consistent with an implantology application. The Chitosan-coated surfaces showed strong inhibition of Actinomyces naeslundii growth; they nonetheless showed a non significant inhibition against Porphyromonas gingivalis after 32 hours in liquid media. The chitosan-coating also demonstrated good biocompatibility to NIH3T3 fibroblasts. Thus this method of covalent coating provides a biocompatible material with improved bioactive properties. These results proved that covalent coating of chitosan has significant potential in biomedical device implantation.

  3. Liver and Renal Function Tests in Artisans Occupationally Exposed to Lead in Mechanic Village in Nnewi, Nigeria

    Directory of Open Access Journals (Sweden)

    S. C. Meludu

    2004-02-01

    Full Text Available Additives in petroleum solvents have been reported to have adverse health implications. An evaluation study on some toxicological effects of occupational exposure to petroleum products (especially petrol which contains tetraethyl lead amongst twenty five occupationally exposed artisans and twenty five graduate students of College of Health Sciences, Nnamdi Azikiwe University, Nnewi, Nigeria as controls, was carried out using the following biochemical markers: electrolytes, urea, uric acid, inorganic phosphorus, creatinine, zinc and blood lead, as well as the activities of alanine and aspartate aminotransferases, and alkaline phosphatase. The results showed that occupational exposure of human subjects to lead in petrol increases the concentrations of uric acid (357 ± 123μ mol/L and phosphate (1.5 ± 0.5m mol/L in exposed subjects compared with unexposed subjects (uric acid 228 ± 105μ mol/L, phosphate 1.2 ± 0.41m mol/L; p < 0.01 in both cases. Significantly lower activities were observed for alkaline phosphatase (66 ± 18.9 iu/L. The activities of alanine aminotransferase (11.4 ± 4.0 iu/L and aspartate aminotransferase (15.8 ± 4.4 iu/L in occupationally exposed artisans were higher compared with unexposed subjects (alkaline phosphatase = 78 ± 22.4 iu/L alanine aminotranferase = 6.8 ± 2.7 iu/L, aspartate aminotranferase = 9.6 ± 3.5i u/L; p < 0.01 in all cases. Occupational exposure of human subjects to lead significantly increased blood lead (59.6 ± 15.9 μg/dL and decreased plasma zinc (71.3 ± 14.4 μg/L in exposed compared with unexposed subjects (blood lead = 35 ± 7 μg/dL, zinc = 108.4 ± 16.9 μg/dL; p < 0.01. The results indicate that occupational exposure to lead in petrol may compromise liver and renal function.

  4. Preparing for and implementing the UN secretary-general's mechanism on alleged use investigation for biological weapons

    International Nuclear Information System (INIS)

    Kraatz-Wadsack, G.

    2009-01-01

    The United Nations Global Counter-Terrorism Strategy was adopted by the UN General Assembly in September 2006. Preventing and responding to attacks using WMD were identified amongst the key areas of activities covered by the strategy. The Secretary-General's mechanism to carry out prompt investigations in response to allegations brought to his attention concerning the possible use of chemical and bacteriological (biological) and toxin weapons was developed in the late 1980s. Triggered by a request from any member State, the Secretary-General is authorized to launch an investigation including dispatching a fact-finding team to the site of the alleged incident(s) and to report to all UN Member States. This is to ascertain in an objective and scientific manner facts of alleged violations of the 1925 Geneva Protocol, which bans the use of chemical and biological weapons. Member States encouraged the Secretary-General in September 2006 to update the roster of experts and laboratories, as well as the technical guidelines and procedures, available to him for the timely and efficient investigation of alleged use. The roster of experts and laboratories and the guidelines and procedures constitute the key elements of the special mechanism available to the Secretary-General for investigation of reports by Member States of alleged use of chemical, biological and toxin weapons. The Office for Disarmament Affairs has been working with Member States since March 2007 to update the roster of experts and laboratories and the technical appendices of the guidelines and procedures so that they fully correspond with the rapid and substantial developments that have occurred in the biological area since the 1980s and also to take into account the fact that an Organization for the Prohibition of Chemical Weapons (OPCW) has since been established. Currently, the roster of experts and laboratories has been updated and includes experts from more than 50 countries. The information available in

  5. Preparing for and implementing the UN secretary-general's mechanism on alleged use investigation for biological weapons

    Energy Technology Data Exchange (ETDEWEB)

    Kraatz-Wadsack, G [Department for Disarmament Affairs at the United Nations, UN Office for Disarmament Affairs (UNODA), New York (United States)

    2009-07-01

    The United Nations Global Counter-Terrorism Strategy was adopted by the UN General Assembly in September 2006. Preventing and responding to attacks using WMD were identified amongst the key areas of activities covered by the strategy. The Secretary-General's mechanism to carry out prompt investigations in response to allegations brought to his attention concerning the possible use of chemical and bacteriological (biological) and toxin weapons was developed in the late 1980s. Triggered by a request from any member State, the Secretary-General is authorized to launch an investigation including dispatching a fact-finding team to the site of the alleged incident(s) and to report to all UN Member States. This is to ascertain in an objective and scientific manner facts of alleged violations of the 1925 Geneva Protocol, which bans the use of chemical and biological weapons. Member States encouraged the Secretary-General in September 2006 to update the roster of experts and laboratories, as well as the technical guidelines and procedures, available to him for the timely and efficient investigation of alleged use. The roster of experts and laboratories and the guidelines and procedures constitute the key elements of the special mechanism available to the Secretary-General for investigation of reports by Member States of alleged use of chemical, biological and toxin weapons. The Office for Disarmament Affairs has been working with Member States since March 2007 to update the roster of experts and laboratories and the technical appendices of the guidelines and procedures so that they fully correspond with the rapid and substantial developments that have occurred in the biological area since the 1980s and also to take into account the fact that an Organization for the Prohibition of Chemical Weapons (OPCW) has since been established. Currently, the roster of experts and laboratories has been updated and includes experts from more than 50 countries. The information available in

  6. The Effects of Short-Term Propofol and Dexmedetomidine on Lung Mechanics, Histology, and Biological Markers in Experimental Obesity.

    Science.gov (United States)

    Heil, Luciana Boavista Barros; Santos, Cíntia L; Santos, Raquel S; Samary, Cynthia S; Cavalcanti, Vinicius C M; Araújo, Mariana M P N; Poggio, Hananda; Maia, Lígia de A; Trevenzoli, Isis Hara; Pelosi, Paolo; Fernandes, Fatima C; Villela, Nivaldo R; Silva, Pedro L; Rocco, Patricia R M

    2016-04-01

    Administering anesthetics to the obese population requires caution because of a variety of reasons including possible interactions with the inflammatory process observed in obese patients. Propofol and dexmedetomidine have protective effects on pulmonary function and are widely used in short- and long-term sedation, particularly in intensive care unit settings in lean and obese subjects. However, the functional and biological effects of these drugs in obesity require further elucidation. In a model of diet-induced obesity, we compared the short-term effects of dexmedetomidine versus propofol on lung mechanics and histology, as well as biological markers of inflammation and oxidative stress modulation in obesity. Wistar rats (n = 56) were randomly fed a standard diet (lean) or experimental diet (obese) for 12 weeks. After this period, obese animals received sodium thiopental intraperitoneally and were randomly allocated into 4 subgroups: (1) nonventilated (n = 4) for molecular biology analysis only (control); (2) sodium thiopental (n = 8); (3) propofol (n = 8); and (4) dexmedetomidine (n = 8), which received continuous IV administration of the corresponding agents and were mechanically ventilated (tidal volume = 6 mL/kg body weight, fraction of inspired oxygen = 0.4, positive end-expiratory pressure = 3 cm H2O) for 1 hour. Compared with lean animals, obese rats did not present increased body weight but had higher total body and trunk fat percentages, airway resistance, and interleukin-6 levels in the lung tissue (P = 0.02, P = 0.0027, and P = 0.01, respectively). In obese rats, propofol, but not dexmedetomidine, yielded increased airway resistance, bronchoconstriction index (P = 0.016, P = 0.02, respectively), tumor necrosis factor-α, and interleukin-6 levels, as well as lower levels of nuclear factor-erythroid 2-related factor-2 and glutathione peroxidase (P = 0.001, Bonferroni-corrected t test). In this model of diet-induced obesity, a 1-hour propofol infusion

  7. Synthesis, Biological Evaluation, and Autophagy Mechanism of 12N-Substituted Sophoridinamines as Novel Anticancer Agents.

    Science.gov (United States)

    Bi, Chongwen; Zhang, Na; Yang, Peng; Ye, Cheng; Wang, Yanxiang; Fan, Tianyun; Shao, Rongguang; Deng, Hongbin; Song, Danqing

    2017-02-09

    A series of 12 N -substituted sophoridinamine derivatives were synthesized and evaluated for their cytotoxic activities in human HepG2 hepatoma cells. Structure-activity relationship revealed that introduction of a suitable arylidene or arylethyl at the N '-end could greatly enhance antiproliferation potency. Among them, compound 6b possessing a N '-trimethoxyphenyl methylene exhibited potent antiproliferation effect against three human tumor cell lines including HepG2, leukemia (K562), and breast cancer (HMLE), with IC 50 between 0.55 and 1.7 μM. The underlying mechanism of 6b against tumor cells is to block autophagic flux, mainly through neutralizing lysosomal acidity. Our results indicated that compound 6b is a potent lysosomal deacidification agent and is accordingly able to block autophagic flux and inhibit tumor cell growth.

  8. Genetic diversity in the oral pathogen Porphyromonas gingivalis: molecular mechanisms and biological consequences

    Science.gov (United States)

    Tribble, Gena D; Kerr, Jennifer E; Wang, Bing-Yan

    2013-01-01

    Porphyromonas gingivalis is a Gram-negative anaerobic bacterium that colonizes the human oral cavity. It is implicated in the development of periodontitis, a chronic periodontal disease affecting half of the adult population in the USA. To survive in the oral cavity, these bacteria must colonize dental plaque biofilms in competition with other bacterial species. Long-term survival requires P. gingivalis to evade host immune responses, while simultaneously adapting to the changing physiology of the host and to alterations in the plaque biofilm. In reflection of this highly variable niche, P. gingivalis is a genetically diverse species and in this review the authors summarize genetic diversity as it relates to pathogenicity in P. gingivalis. Recent studies revealing a variety of mechanisms by which adaptive changes in genetic content can occur are also reviewed. Understanding the genetic plasticity of P. gingivalis will provide a better framework for understanding the host–microbe interactions associated with periodontal disease. PMID:23642116

  9. Repair of endogenous and ionizing radiation-induced DNA damages: mechanisms and biological functions

    International Nuclear Information System (INIS)

    Boiteux, S.

    2002-01-01

    The cellular DNA is continuously exposed to endogenous and exogenous stress. Oxidative stress due to cellular metabolism is the major cause of endogenous DNA damage. On the other hand, ionizing radiation (IR) is an important exogenous stress. Both induce similar DNA damages: damaged bases, abasic sites and strand breakage. Most of these lesions are lethal and/or mutagenic. The survival of the cell is managed by efficient and accurate DNA repair mechanisms that remove lesions before their replication or transcription. DNA repair pathways involved in the removal of IR-induced lesions are briefly described. Base excision repair (BER) is mostly involved in the removal of base damage, abasic sites and single strand breaks. In contrast, DNA double strand breaks are mostly repaired by non-homologous end joining (NHEJ) or homologous recombination (HR). How DNA repair pathways prevent cancer process is also discussed. (author)

  10. Ebselen, a promising antioxidant drug: mechanisms of action and targets of biological pathways.

    Science.gov (United States)

    Azad, Gajendra Kumar; Tomar, Raghuvir S

    2014-08-01

    Ebselen, an organoselenium compound, mimics glutathione peroxidase activity. It is a multifunctional compound, which catalyzes several essential reactions for the protection of cellular components from oxidative and free radical damage. Based on a number of in vitro and in vivo studies, various mechanisms are proposed to understand the biomedical actions of ebselen in health and diseases. It modulates metallo-proteins, enzymatic cofactors, gene expression, epigenetics, antioxidant defenses and immune systems. Owing to these properties, ebselen is currently under clinical trials for the prevention and treatment of various disorders such as cardiovascular diseases, arthritis, stroke, atherosclerosis, and cancer. A few ebselen-based pharmaceutical agents are under extensive investigation. As ebselen has been shown to have significant cellular toxicity, appropriate studies are needed to redesign the ebselen-based therapy for clinical trials. This review summarizes current understanding of the biochemical and molecular properties, and pharmacological applications of ebselen and future directions in this area of research.

  11. [Bone Cell Biology Assessed by Microscopic Approach. Response to mechanical stress by osteocyte network].

    Science.gov (United States)

    Komori, Toshihisa

    2015-10-01

    Osteocytes were considered to be involved in the response to mechanical stress from their network structure. However, it was difficult to prove the function because of the lack of animal models for a long time. Recently, the function of osteocytes was clarified using various knockout and transgenic mice. Osteocyte death causes bone remodeling, which is a repair process induced by osteocyte necrosis but not by the loss of the function of live osteocytes. The osteocyte network mildly inhibits bone formation and mildly stimulates bone resorption in physiological condition. In unloaded condition, it strongly inhibits bone formation and strongly stimulates bone resorption, at least in part, through the induction of Sost in osteocytes and Rankl in osteoblasts.

  12. Mechanical characteristic and biological behaviour of implanted and restorative bioglasses used in medicine and dentistry: A systematic review.

    Science.gov (United States)

    Lizzi, F; Villat, C; Attik, N; Jackson, P; Grosgogeat, B; Goutaudier, C

    2017-06-01

    Nowadays bioactive glasses are finding increasing applications in medical practice due to their ability to stimulate re-mineralisation. However, they are intrinsically brittle materials and the study of new compositions will open up new scenarios enhancing their mechanical properties and maintaining the high bioactivity for a broader range of applications. This systematic review aims to identify the relationship between the composition of bioactive glasses used in medical applications and their influence on the mechanical and biological properties. Various electronic databases (PubMed, Science Direct) were used for collecting articles on this subject. This research includes papers from January 2011 to March 2016. PRISMA guidelines for systematic review and meta-analysis have been used. 109 abstracts were collected and screened, 68 articles were read as relevant articles and a total of 22 papers were finally selected for this study. Most of the studies obtained enhanced mechanical properties and the conservation of bioactivity behaviours; although a lack of homogeneity in the characterization methods makes it difficult to compare data. New compositions of bioactive glasses incorporating specific ions and the addition in polymers will be the most important direction for future researches in developing new materials for medical applications and especially for dentistry. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Lead-Cooled Fast Reactor (LFR) Design: Safety, Neutronics, Thermal Hydraulics, Structural Mechanics, Fuel, Core, and Plant Design

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C

    2010-02-22

    The idea of developing fast spectrum reactors with molten lead (or lead alloy) as a coolant is not a new one. Although initially considered in the West in the 1950s, such technology was not pursued to completion because of anticipated difficulties associated with the corrosive nature of these coolant materials. However, in the Soviet Union, such technology was actively pursued during the same time frame (1950s through the 1980s) for the specialized role of submarine propulsion. More recently, there has been a renewal of interest in the West for such technology, both for critical systems as well as for Accelerator Driven Subcritical (ADS) systems. Meanwhile, interest in the former Soviet Union, primarily Russia, has remained strong and has expanded well beyond the original limited mission of submarine propulsion. This section reviews the past and current status of LFR development.

  14. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    Science.gov (United States)

    Ma, Ming-Guo

    2012-01-01

    Hierarchically nanosized hydroxyapatite (HA) with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours. Objective The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA) with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks. Methods A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did not decrease with the increasing concentration of hierarchically nanostructured HA added. Conclusion A novel, simple and reliable hydrothermal route had been developed for the synthesis of

  15. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    Directory of Open Access Journals (Sweden)

    Ma MG

    2012-04-01

    Full Text Available Ming-Guo MaInstitute of Biomass Chemistry and Technology, College of Materials Science and Technology, Beijing Forestry University, Beijing, People's Republic of ChinaAbstract: Hierarchically nanosized hydroxyapatite (HA with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours.Objective: The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks.Methods: A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay.Results: HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did

  16. Fabrication of electrospun HPGL scaffolds via glycidyl methacrylate cross-linker: Morphology, mechanical and biological properties

    Energy Technology Data Exchange (ETDEWEB)

    Baratéla, Fernando José Costa; Zazuco Higa, Olga [Biotechnology Center, Institute of Energy and Nuclear Research (IPEN), Av. Professor Lineu Prestes 2242, 05508-000 São Paulo, SP (Brazil); Duarte dos Passos, Esdras [PostGraduate Program in Materials for Engineering, Federal University of Itajubá (UNIFEI), Av. BPS 1303, 37500-903 Itajubá, MG (Brazil); Alencar de Queiroz, Alvaro Antonio, E-mail: alencar@unifei.edu.br [Physics and Chemistry Institute (IFQ), Federal University of Itajubá (UNIFEI), Av. BPS 1303, 37500-903 Itajubá, MG (Brazil); High Voltage Laboratory (LAT-EFEI), Federal University of Itajubá (UNIFEI), Av. BPS 1303, 37500-903 Itajubá, MG (Brazil)

    2017-04-01

    Electrospinning is a suitable method to produce scaffolds composed of nanoscale to microscale fibers, which are comparable to the extracellular matrix (ECM). Hyperbranched polyglycerol (HPGL) is a highly biocompatible polyether polyol potentially useful for the design of fibrous scaffolds mimicking the ECM architecture. However, scaffolds developed from HPGL have poor mechanical properties and morphological stability in the aqueous environments required for tissue engineering applications. This work reports the production of stable electrospun HPGL scaffolds (EHPGLS) using glycidyl methacrylate (GMA) as cross-linker to enhance the water stability and mechanical property of electrospun HPGL. The diameter and morphology of the produced EHPGLS were analyzed by scanning electron microscopy (SEM). It was observed that electrical fields in the range of 0.2 kV·cm{sup −1} to 1.0 kV·cm{sup −1} decrease the average fiber diameter of EHPGLS. The increase in porosity of EHPGLS with GMA concentration indicates the in situ formation of a heterogeneous structure resultant from the phase separation during crosslinking of HPGL by GMA. EHPGLS containing 20% (w/w) GMA concentration possessed highest tensile strength (295.4 ± 11.32 kPa), which is approximately 58 times higher than that of non-crosslinked EHPGLS (5.1 ± 2.12 kPa). The MTS cell viability results showed that the EHPGLS have no significant cytotoxicity effect on Chinese hamster ovary (CHO-K1) cells. Scanning electron microscopy (SEM) indicates that the cultured BALB/3T3 fibroblasts cells were able to keep contact each other's, thus forming a homogeneous monolayer on the internal surface of the EHPGLS. - Highlights: • A hyperbranched polyglycerol (HPGL) scaffold with elastic modulus of 295.4 ± 11.32 kPa was developed for soft tissue repair. • HPGL scaffold was prepared by electrospinning method. • The porosity of HPGL scaffolds can be tuned by selecting the degree of GMA in HPGL. • Electrospun HPGL

  17. Theoretical study of chromophores for biological sensing: Understanding the mechanism of rhodol based multi-chromophoric systems

    Science.gov (United States)

    Rivera-Jacquez, Hector J.; Masunov, Artëm E.

    2018-06-01

    Development of two-photon fluorescent probes can aid in visualizing the cellular environment. Multi-chromophore systems display complex manifolds of electronic transitions, enabling their use for optical sensing applications. Time-Dependent Density Functional Theory (TDDFT) methods allow for accurate predictions of the optical properties. These properties are related to the electronic transitions in the molecules, which include two-photon absorption cross-sections. Here we use TDDFT to understand the mechanism of aza-crown based fluorescent probes for metals sensing applications. Our findings suggest changes in local excitation in the rhodol chromophore between unbound form and when bound to the metal analyte. These changes are caused by a charge transfer from the aza-crown group and pyrazol units toward the rhodol unit. Understanding this mechanism leads to an optimized design with higher two-photon excited fluorescence to be used in medical applications.

  18. Training mechanical engineering students to utilize biological inspiration during product development.

    Science.gov (United States)

    Bruck, Hugh A; Gershon, Alan L; Golden, Ira; Gupta, Satyandra K; Gyger, Lawrence S; Magrab, Edward B; Spranklin, Brent W

    2007-12-01

    The use of bio-inspiration for the development of new products and devices requires new educational tools for students consisting of appropriate design and manufacturing technologies, as well as curriculum. At the University of Maryland, new educational tools have been developed that introduce bio-inspired product realization to undergraduate mechanical engineering students. These tools include the development of a bio-inspired design repository, a concurrent fabrication and assembly manufacturing technology, a series of undergraduate curriculum modules and a new senior elective in the bio-inspired robotics area. This paper first presents an overview of the two new design and manufacturing technologies that enable students to realize bio-inspired products, and describes how these technologies are integrated into the undergraduate educational experience. Then, the undergraduate curriculum modules are presented, which provide students with the fundamental design and manufacturing principles needed to support bio-inspired product and device development. Finally, an elective bio-inspired robotics project course is present, which provides undergraduates with the opportunity to demonstrate the application of the knowledge acquired through the curriculum modules in their senior year using the new design and manufacturing technologies.

  19. Sequence-dependent response of DNA to torsional stress: a potential biological regulation mechanism.

    Science.gov (United States)

    Reymer, Anna; Zakrzewska, Krystyna; Lavery, Richard

    2018-02-28

    Torsional restraints on DNA change in time and space during the life of the cell and are an integral part of processes such as gene expression, DNA repair and packaging. The mechanical behavior of DNA under torsional stress has been studied on a mesoscopic scale, but little is known concerning its response at the level of individual base pairs and the effects of base pair composition. To answer this question, we have developed a geometrical restraint that can accurately control the total twist of a DNA segment during all-atom molecular dynamics simulations. By applying this restraint to four different DNA oligomers, we are able to show that DNA responds to both under- and overtwisting in a very heterogeneous manner. Certain base pair steps, in specific sequence environments, are able to absorb most of the torsional stress, leaving other steps close to their relaxed conformation. This heterogeneity also affects the local torsional modulus of DNA. These findings suggest that modifying torsional stress on DNA could act as a modulator for protein binding via the heterogeneous changes in local DNA structure.

  20. Radiation-induced bystander effects. Mechanisms, biological implications, and current investigations at the Leipzig LIPSION facility

    International Nuclear Information System (INIS)

    Oesterreicher, J.; Prise, K.M.; Michael, B.D.; Vogt, J.; Butz, T.; Tanner, J.M.

    2003-01-01

    Background: The bystander effect is a relatively new area of radiobiological research, which is aimed at studying post-radiation changes in neighboring non-hit cells or tissues. The bystander effect of ionizing irradiation is important after low-dose irradiation in the range of up to 0.2 Gy, where a higher incidence of stochastic damage was observed than was expected from a linear-quadratic model. It is also important when the irradiation of a cell population is highly non-uniform. Objective: This review summarizes most of the important results and proposed bystander effect mechanisms as well as their impact on theory and clinical practice. The literature, in parts contradictory, is collected, the main topics are outlined, and some basic papers are described in more detail. In order to illustrate the microbeam technique, which is considered relevant for the bystander effect research, the state of the Leipzig LIPSION nanoprobe facility is described. Results: The existence of a radiation-induced bystander effect is now generally accepted. The current state of knowledge on it is summarized here. Several groups worldwide are working on understanding its different aspects and its impact on radiobiology and radiation protection. Conclusion: The observation of a bystander effect has posed many questions, and answering them is a challenging topic for radiobiology in the future. (orig.)

  1. Radiation-induced bystander effects. Mechanisms, biological implications, and current investigations at the Leipzig LIPSION facility

    Energy Technology Data Exchange (ETDEWEB)

    Oesterreicher, J. [Dept. of Nuclear Solid State Physics, Univ. of Leipzig (Germany); Dept. of Radiobiology and Immunology, Purkyne Military Medical Academy, Hradec Kralove (Czech Republic); Prise, K.M.; Michael, B.D. [Gray Cancer Inst., Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Vogt, J.; Butz, T. [Dept. of Nuclear Solid State Physics, Univ. of Leipzig (Germany); Tanner, J.M. [Clinic and Polyclinic of Radiation Oncology, Martin Luther Univ. Halle-Wittenberg (Germany)

    2003-02-01

    Background: The bystander effect is a relatively new area of radiobiological research, which is aimed at studying post-radiation changes in neighboring non-hit cells or tissues. The bystander effect of ionizing irradiation is important after low-dose irradiation in the range of up to 0.2 Gy, where a higher incidence of stochastic damage was observed than was expected from a linear-quadratic model. It is also important when the irradiation of a cell population is highly non-uniform. Objective: This review summarizes most of the important results and proposed bystander effect mechanisms as well as their impact on theory and clinical practice. The literature, in parts contradictory, is collected, the main topics are outlined, and some basic papers are described in more detail. In order to illustrate the microbeam technique, which is considered relevant for the bystander effect research, the state of the Leipzig LIPSION nanoprobe facility is described. Results: The existence of a radiation-induced bystander effect is now generally accepted. The current state of knowledge on it is summarized here. Several groups worldwide are working on understanding its different aspects and its impact on radiobiology and radiation protection. Conclusion: The observation of a bystander effect has posed many questions, and answering them is a challenging topic for radiobiology in the future. (orig.)

  2. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2012-02-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  3. Effects of alginate hydrogel cross-linking density on mechanical and biological behaviors for tissue engineering.

    Science.gov (United States)

    Jang, Jinah; Seol, Young-Joon; Kim, Hyeon Ji; Kundu, Joydip; Kim, Sung Won; Cho, Dong-Woo

    2014-09-01

    An effective cross-linking of alginate gel was made through reaction with calcium carbonate (CaCO3). We used human chondrocytes as a model cell to study the effects of cross-linking density. Three different pore size ranges of cross-linked alginate hydrogels were fabricated. The morphological, mechanical, and rheological properties of various alginate hydrogels were characterized and responses of biosynthesis of cells encapsulated in each gel to the variation in cross-linking density were investigated. Desired outer shape of structure was maintained when the alginate solution was cross-linked with the applied method. The properties of alginate hydrogel could be tailored through applying various concentrations of CaCO3. The rate of synthesized GAGs and collagens was significantly higher in human chondrocytes encapsulated in the smaller pore structure than that in the larger pore structure. The expression of chondrogenic markers, including collagen type II and aggrecan, was enhanced in the smaller pore structure. It was found that proper structural morphology is a critical factor to enhance the performance and tissue regeneration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Biological markers of amyloid beta-related mechanisms in Alzheimer's disease.

    LENUS (Irish Health Repository)

    Hampel, Harald

    2010-06-01

    Recent research progress has given detailed knowledge on the molecular pathogenesis of Alzheimer\\'s disease (AD), which has been translated into an intense, ongoing development of disease-modifying treatments. Most new drug candidates are targeted on inhibiting amyloid beta (Abeta) production and aggregation. In drug development, it is important to co-develop biomarkers for Abeta-related mechanisms to enable early diagnosis and patient stratification in clinical trials, and to serve as tools to identify and monitor the biochemical effect of the drug directly in patients. Biomarkers are also requested by regulatory authorities to serve as safety measurements. Molecular aberrations in the AD brain are reflected in the cerebrospinal fluid (CSF). Core CSF biomarkers include Abeta isoforms (Abeta40\\/Abeta42), soluble APP isoforms, Abeta oligomers and beta-site APP-cleaving enzyme 1 (BACE1). This article reviews recent research advances on core candidate CSF and plasma Abeta-related biomarkers, and gives a conceptual review on how to implement biomarkers in clinical trials in AD.

  5. The biological mechanisms and behavioral functions of opsin-based light detection by the skin

    Directory of Open Access Journals (Sweden)

    Jennifer L Kelley

    2016-08-01

    Full Text Available Light detection not only forms the basis of vision (via visual retinal photoreceptors, but can also occur in other parts of the body, including many non-rod/non-cone ocular cells, the pineal complex, the deep brain, and the skin. Indeed, many of the photopigments (an opsin linked to a light-sensitive 11-cis retinal chromophore that mediate color vision in the eyes of vertebrates are also present in the skin of animals such as reptiles, amphibians, crustaceans and fishes (with related photoreceptive molecules present in cephalopods, providing a localized mechanism for light detection across the surface of the body. This form of non-visual photosensitivity may be particularly important for animals that can change their coloration by altering the dispersion of pigments within the chromatophores (pigment containing cells of the skin. Thus, skin coloration may be directly color matched or tuned to both the luminance and spectral properties of the local background environment, thereby facilitating behavioral functions such as camouflage, thermoregulation, and social signaling. This review examines the diversity and sensitivity of opsin-based photopigments present in the skin and considers their putative functional roles in mediating animal behavior. Furthermore, it discusses the potential underlying biochemical and molecular pathways that link shifts in environmental light to both photopigment expression and chromatophore photoresponses. Although photoreception that occurs independently of image formation remains poorly understood, this review highlights the important role of non-visual light detection in facilitating the multiple functions of animal coloration.

  6. Insight into the adsorption mechanisms of trace organic carbon on biological treatment process.

    Science.gov (United States)

    Zolfaghari, Mehdi; Drogui, Patrick; Brar, Satinder Kaur; Buelna, Gerardo; Dubé, Rino

    2017-09-01

    The presence of recalcitrant dissolved organic matter (DOM) could have a significant effect on the adsorption mechanism and capacity of the sludge for many trace organic carbons (TrOCs). In this study, adsorption of three TrOCs on the sludge and HA was investigated. The results revealed that neutral hydrophilic compounds had an insignificant interaction with both sludge and HA. Positively charged compounds, such as fluoranthene, had more affinity toward HA than sludge with solid/liquid partitioning of 57 and 3.2 L/g, respectively. The adsorption intensity (K f ) of di-2-ethyl hexyl phthalate was 0.5 and 1.13 for the HA and the sludge, respectively. By introducing the sludge to the solution of HA and TrOCs that already reached equilibrium, the sludge adsorption capacity in the presence of HA was investigated. The finding showed that at the lower concentration, adsorption of HA on the sludge was considered as the main removal pathway for the adsorbed emerging contaminants, as 70 mg of HA was adsorbed by a gram of sludge. For the higher concentration, desorption of TrOCs from DOM into the sludge comprised 15-30% of total removal efficiency. CBZ: carbamazepine; DEHP: di-2-ethyl hexyl phthalate; DOM: dissolved organic matter; FLAN: fluoranthene; f oc : fraction of organic carbon; HA: humic acid; Log Kow: octanol-water partition coefficient; PAH: polycyclic aromatic hydrocarbon TS: total solid; TrOCs: trace organic carbons VS: volatile solid.

  7. A review of cutting mechanics and modeling techniques for biological materials.

    Science.gov (United States)

    Takabi, Behrouz; Tai, Bruce L

    2017-07-01

    This paper presents a comprehensive survey on the modeling of tissue cutting, including both soft tissue and bone cutting processes. In order to achieve higher accuracy in tissue cutting, as a critical process in surgical operations, the meticulous modeling of such processes is important in particular for surgical tool development and analysis. This review paper is focused on the mechanical concepts and modeling techniques utilized to simulate tissue cutting such as cutting forces and chip morphology. These models are presented in two major categories, namely soft tissue cutting and bone cutting. Fracture toughness is commonly used to describe tissue cutting while Johnson-Cook material model is often adopted for bone cutting in conjunction with finite element analysis (FEA). In each section, the most recent mathematical and computational models are summarized. The differences and similarities among these models, challenges, novel techniques, and recommendations for future work are discussed along with each section. This review is aimed to provide a broad and in-depth vision of the methods suitable for tissue and bone cutting simulations. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  8. Brown rot fungal early stage decay mechanism as a biological pretreatment for softwood biomass in biofuel production

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Michael J.; Leak, David J.; Spanu, Pietro D.; Murphy, Richard J. [Division of Biology, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ (United Kingdom); Porter Alliance, Imperial College London, London SW7 2AZ (United Kingdom)

    2010-08-15

    A current barrier to the large-scale production of lignocellulosic biofuels is the cost associated with the energy and chemical inputs required for feedstock pretreatment and hydrolysis. The use of controlled partial biological degradation to replace elements of the current pretreatment technologies would offer tangible energy and cost benefits to the whole biofuel process. It has been known for some time from studies of wood decay that, in the early stages of growth in wood, brown rot fungi utilise a mechanism that causes rapid and extensive depolymerisation of the carbohydrate polymers of the wood cell wall. The brown rot hyphae act as delivery vectors to the plant cell wall for what is thought to be a combination of a localised acid pretreatment and a hydroxyl radical based depolymerisation of the cell wall carbohydrate polymers. It is this quality that we have exploited in the present work to enhance the saccharification potential of softwood forest residues for biofuel production. Here we show that after restricted exposure of pine sapwood to brown rot fungi, glucose yields following enzymatic saccharification are significantly increased. Our results demonstrate the potential of using brown rot fungi as a biological pretreatment for biofuel production. (author)

  9. Theoretical study of electron transfer mechanism in biological systems with a QM (MRSCI+DFT)/MM method

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Toshikazu [Research Program for Computational Science, RIKEN 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan)

    2007-07-15

    The goal of this project is to understand the charge separation mechanisms in biological systems using the molecular orbital theories. Specially, the charge separation in the photosynthetic reaction center is focused on, since the efficiency in use of the solar energy is extraordinary and the reason for it is still kept unknown. Here, a QM/MM theoretical scheme is employed to take the effects of the surrounding proteins onto the pigments into account. To describe such excited electronic structures, a unified theory by MRSCI and DFT is newly invented. For atoms in the MM space, a new sampling method has also been created, based on the statistical physics. By using these theoretical framework, the excited and positively charged states of the special pair, that is, chlorophyll dimmer are planning to be calculated this year.

  10. Theoretical study of electron transfer mechanism in biological systems with a QM (MRSCI+DFT)/MM method

    International Nuclear Information System (INIS)

    Takada, Toshikazu

    2007-01-01

    The goal of this project is to understand the charge separation mechanisms in biological systems using the molecular orbital theories. Specially, the charge separation in the photosynthetic reaction center is focused on, since the efficiency in use of the solar energy is extraordinary and the reason for it is still kept unknown. Here, a QM/MM theoretical scheme is employed to take the effects of the surrounding proteins onto the pigments into account. To describe such excited electronic structures, a unified theory by MRSCI and DFT is newly invented. For atoms in the MM space, a new sampling method has also been created, based on the statistical physics. By using these theoretical framework, the excited and positively charged states of the special pair, that is, chlorophyll dimmer are planning to be calculated this year

  11. Molecular mechanisms of nematode-nematophagous microbe interactions: basis for biological control of plant-parasitic nematodes.

    Science.gov (United States)

    Li, Juan; Zou, Chenggang; Xu, Jianping; Ji, Xinglai; Niu, Xuemei; Yang, Jinkui; Huang, Xiaowei; Zhang, Ke-Qin

    2015-01-01

    Plant-parasitic nematodes cause significant damage to a broad range of vegetables and agricultural crops throughout the world. As the natural enemies of nematodes, nematophagous microorganisms offer a promising approach to control the nematode pests. Some of these microorganisms produce traps to capture and kill the worms from the outside. Others act as internal parasites to produce toxins and virulence factors to kill the nematodes from within. Understanding the molecular basis of microbe-nematode interactions provides crucial insights for developing effective biological control agents against plant-parasitic nematodes. Here, we review recent advances in our understanding of the interactions between nematodes and nematophagous microorganisms, with a focus on the molecular mechanisms by which nematophagous microorganisms infect nematodes and on the nematode defense against pathogenic attacks. We conclude by discussing several key areas for future research and development, including potential approaches to apply our recent understandings to develop effective biocontrol strategies.

  12. New Insights Into the Mechanisms and Biological Roles of D-Amino Acids in Complex Eco-Systems

    Science.gov (United States)

    Aliashkevich, Alena; Alvarez, Laura; Cava, Felipe

    2018-01-01

    In the environment bacteria share their habitat with a great diversity of organisms, from microbes to humans, animals and plants. In these complex communities, the production of extracellular effectors is a common strategy to control the biodiversity by interfering with the growth and/or viability of nearby microbes. One of such effectors relies on the production and release of extracellular D-amino acids which regulate diverse cellular processes such as cell wall biogenesis, biofilm integrity, and spore germination. Non-canonical D-amino acids are mainly produced by broad spectrum racemases (Bsr). Bsr’s promiscuity allows it to generate high concentrations of D-amino acids in environments with variable compositions of L-amino acids. However, it was not clear until recent whether these molecules exhibit divergent functions. Here we review the distinctive biological roles of D-amino acids, their mechanisms of action and their modulatory properties of the biodiversity of complex eco-systems. PMID:29681896

  13. Physical-biological coupling induced aggregation mechanism for the formation of high biomass red tides in low nutrient waters.

    Science.gov (United States)

    Lai, Zhigang; Yin, Kedong

    2014-01-01

    Port Shelter is a semi-enclosed bay in northeast Hong Kong where high biomass red tides are observed to occur frequently in narrow bands along the local bathymetric isobars. Previous study showed that nutrients in the Bay are not high enough to support high biomass red tides. The hypothesis is that physical aggregation and vertical migration of dinoflagellates appear to be the driving mechanism to promote the formation of red tides in this area. To test this hypothesis, we used a high-resolution estuarine circulation model to simulate the near-shore water dynamics based on in situ measured temperature/salinity profiles, winds and tidal constitutes taken from a well-validated regional tidal model. The model results demonstrated that water convergence occurs in a narrow band along the west shore of Port Shelter under a combined effect of stratified tidal current and easterly or northeasterly wind. Using particles as dinoflagellate cells and giving diel vertical migration, the model results showed that the particles aggregate along the convergent zone. By tracking particles in the model predicted current field, we estimated that the physical-biological coupled processes induced aggregation of the particles could cause 20-45 times enhanced cell density in the convergent zone. This indicated that a high cell density red tide under these processes could be initialized without very high nutrients concentrations. This may explain why Port Shelter, a nutrient-poor Bay, is the hot spot for high biomass red tides in Hong Kong in the past 25 years. Our study explains why red tide occurrences are episodic events and shows the importance of taking the physical-biological aggregation mechanism into consideration in the projection of red tides for coastal management. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Doped tricalcium phosphate bone tissue engineering scaffolds using sucrose as template and microwave sintering: enhancement of mechanical and biological properties.

    Science.gov (United States)

    Ke, Dongxu; Bose, Susmita

    2017-09-01

    β-tricalcium phosphate (β-TCP) is a widely used biocompatible ceramic in orthopedic and dental applications. However, its osteoinductivity and mechanical properties still require improvements. In this study, porous β-TCP and MgO/ZnO-TCP scaffolds were prepared by the thermal decomposition of sucrose. Crack-free cylindrical scaffolds could only be prepared with the addition of MgO and ZnO due to their stabilization effects. Porous MgO/ZnO-TCP scaffolds with a density of 61.39±0.66%, an estimated pore size of 200μm and a compressive strength of 24.96±3.07MPa were prepared by using 25wt% sucrose after conventional sintering at 1250°C. Microwave sintering further increased the compressive strength to 37.94±6.70MPa, but it decreased the open interconnected porosity to 8.74±1.38%. In addition, the incorporation of polycaprolactone (PCL) increased 22.36±3.22% of toughness while maintaining its compressive strength at 25.45±2.21MPa. Human osteoblast cell line was seeded on scaffolds to evaluate the effects of MgO/ZnO and PCL on the biological property of β-TCP in vitro. Both MgO/ZnO and PCL improved osteoinductivity of β-TCP. PCL also decreased osteoblastic apoptosis due to its particular surface chemistry. This novel porous MgO/ZnO-TCP scaffold with PCL shows improved mechanical and biological properties, which has great potential in bone tissue engineering applications. Copyright © 2017. Published by Elsevier B.V.

  15. A systems biology strategy to identify molecular mechanisms of action and protein indicators of traumatic brain injury.

    Science.gov (United States)

    Yu, Chenggang; Boutté, Angela; Yu, Xueping; Dutta, Bhaskar; Feala, Jacob D; Schmid, Kara; Dave, Jitendra; Tawa, Gregory J; Wallqvist, Anders; Reifman, Jaques

    2015-02-01

    The multifactorial nature of traumatic brain injury (TBI), especially the complex secondary tissue injury involving intertwined networks of molecular pathways that mediate cellular behavior, has confounded attempts to elucidate the pathology underlying the progression of TBI. Here, systems biology strategies are exploited to identify novel molecular mechanisms and protein indicators of brain injury. To this end, we performed a meta-analysis of four distinct high-throughput gene expression studies involving different animal models of TBI. By using canonical pathways and a large human protein-interaction network as a scaffold, we separately overlaid the gene expression data from each study to identify molecular signatures that were conserved across the different studies. At 24 hr after injury, the significantly activated molecular signatures were nonspecific to TBI, whereas the significantly suppressed molecular signatures were specific to the nervous system. In particular, we identified a suppressed subnetwork consisting of 58 highly interacting, coregulated proteins associated with synaptic function. We selected three proteins from this subnetwork, postsynaptic density protein 95, nitric oxide synthase 1, and disrupted in schizophrenia 1, and hypothesized that their abundance would be significantly reduced after TBI. In a penetrating ballistic-like brain injury rat model of severe TBI, Western blot analysis confirmed our hypothesis. In addition, our analysis recovered 12 previously identified protein biomarkers of TBI. The results suggest that systems biology may provide an efficient, high-yield approach to generate testable hypotheses that can be experimentally validated to identify novel mechanisms of action and molecular indicators of TBI. © 2014 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

  16. Hemodynamic Evaluation of a Biological and Mechanical Aortic Valve Prosthesis Using Patient-Specific MRI-Based CFD.

    Science.gov (United States)

    Hellmeier, Florian; Nordmeyer, Sarah; Yevtushenko, Pavlo; Bruening, Jan; Berger, Felix; Kuehne, Titus; Goubergrits, Leonid; Kelm, Marcus

    2018-01-01

    Modeling different treatment options before a procedure is performed is a promising approach for surgical decision making and patient care in heart valve disease. This study investigated the hemodynamic impact of different prostheses through patient-specific MRI-based CFD simulations. Ten time-resolved MRI data sets with and without velocity encoding were obtained to reconstruct the aorta and set hemodynamic boundary conditions for simulations. Aortic hemodynamics after virtual valve replacement with a biological and mechanical valve prosthesis were investigated. Wall shear stress (WSS), secondary flow degree (SFD), transvalvular pressure drop (TPD), turbulent kinetic energy (TKE), and normalized flow displacement (NFD) were evaluated to characterize valve-induced hemodynamics. The biological prostheses induced significantly higher WSS (medians: 9.3 vs. 8.6 Pa, P = 0.027) and SFD (means: 0.78 vs. 0.49, P = 0.002) in the ascending aorta, TPD (medians: 11.4 vs. 2.7 mm Hg, P = 0.002), TKE (means: 400 vs. 283 cm 2 /s 2 , P = 0.037), and NFD (means: 0.0994 vs. 0.0607, P = 0.020) than the mechanical prostheses. The differences between the prosthesis types showed great inter-patient variability, however. Given this variability, a patient-specific evaluation is warranted. In conclusion, MRI-based CFD offers an opportunity to assess the interactions between prosthesis and patient-specific boundary conditions, which may help in optimizing surgical decision making and providing additional guidance to clinicians. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  17. Grain interaction mechanisms leading to intragranular orientation spread in tensile deformed bulk grains of interstitial-free steel

    DEFF Research Database (Denmark)

    Winther, Grethe; Wright, Jonathan P.; Schmidt, Søren

    2017-01-01

    environments representing the bulk texture, yet their deformation-induce