WorldWideScience

Sample records for cell physiological phenomena

  1. Biomedical Signals and Sensors I Linking Physiological Phenomena and Biosignals

    CERN Document Server

    Kaniusas, Eugenijus

    2012-01-01

    This two-volume set focuses on the interface between physiologic mechanisms and diagnostic human engineering. Today numerous biomedical sensors are commonplace in clinical practice. The registered biosignals reflect mostly vital physiologic phenomena. In order to adequately apply biomedical sensors and reasonably interpret the corresponding biosignals, a proper understanding of the involved physiologic phenomena, their influence on the registered biosignals, and the technology behind the sensors is necessary. The first volume is devoted to the interface between physiologic mechanisms and arising biosignals, whereas the second volume is focussed on the interface between biosignals and biomedical sensors. The physiologic mechanisms behind the biosignals are described from the basic cellular level up to their advanced mutual coordination level during sleep. The arising biosignals are discussed within the scope of vital physiologic phenomena to foster their understanding and comprehensive analysis.

  2. From physiological psychology to psychological physiology: Postnonclassical approach to ethnocultural phenomena.

    Directory of Open Access Journals (Sweden)

    Asmolov, A.G.

    2015-07-01

    Full Text Available In modern science, along with the “classic” and “non-classical” approach to solving fundamental and applied problems, there is an actively developing “postnonclassical” research paradigm. This renovation of general scientific methodology has been accompanied by the emergence of new experimental technologies and new scientific research directions based on them. “Social psychophysiology” is one such direction. It is formed within the frame of postnonclassical methodology at the intersection of neuroscience and psychology. This work is devoted to the analytical review of the methods, achievements and prospects of contemporary social neuroscience and social psychophysiology studying brain structures that are specifically related to the implementation of social forms of behavior and intercultural communication. Physiological studies of brain activity during social interaction processes, which are simulated using virtual reality environments, are analyzed, and the physiological approach to the study of the brain mechanisms associated with social perception, social cognition and social behavior is used. Along with the analysis of psychophysiological studies of the mechanisms of social perception and social cognition, we discuss the theories of “Brain Reading” and “Theory of Mind” and the underlying data concerning “Gnostic neurons recognition of persons and recognition of emotional facial expressions”, “mirror neurons”, “emotional resonance” and “cognitive resonance”. Particular emphasis is placed on the discussion of a fundamentally new trend in the study of the relationship between the brain and culture (i.e., “cultural neuroscience”. Related to this connection, the following topics are raised: physiological mechanisms protecting the “individual distance” in communication between members of a personified community, psychophysiological approaches to the study of cross-cultural differences, physiological

  3. Electrostrictive Effect in Cancer Cell Reflected in Capacitance Relaxation Phenomena

    Directory of Open Access Journals (Sweden)

    Tapas Kumar Basak

    2008-12-01

    Full Text Available The present paper has focus on the composite dielectric property of the cancer cell on concomitant with the capacitance relaxation phenomena. In this respect it has been found from MAT lab simulation the electrostrictive process in cancer cell is a complex one for which the electrostatic surfaces surrounding the cell changes with the incremental changes in the capacitance present in the capacitance relaxation curve. From these incremental changes in capacitance it is also possible to find out the electrostrictive energy of the cancer cell. It is interesting to note that the electrostrictive energy corresponding to the cell incremental changes in the capacitance is more in the first order system than that present in the second order system representing the equivalent configuration of the composite dielectric associated with the cell membrane. This is due the fact that during the process DNA synthesis and cell division the change in capacitance of the membrane for the first order system is relatively slow.

  4. Physiology of cell volume regulation in vertebrates

    DEFF Research Database (Denmark)

    Hoffmann, Else K; Lambert, Ian H; Pedersen, Stine F

    2009-01-01

    organisms. Importantly, cell volume impacts on a wide array of physiological processes, including transepithelial transport; cell migration, proliferation, and death; and changes in cell volume function as specific signals regulating these processes. A discussion of this issue concludes the review....

  5. Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian

    An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...... the present fundamental understanding of direct methanol fuel cell operation by developing a three-dimensional, two-phase, multi-component, non-isotherm mathematical model including detailed non-ideal thermodynamics, non-equilibrium phase change and non-equilibrium sorption-desorption of methanol and water...

  6. Fluid models and simulations of biological cell phenomena

    Science.gov (United States)

    Greenspan, H. P.

    1982-01-01

    The dynamics of coated droplets are examined within the context of biofluids. Of specific interest is the manner in which the shape of a droplet, the motion within it as well as that of aggregates of droplets can be controlled by the modulation of surface properties and the extent to which such fluid phenomena are an intrinsic part of cellular processes. From the standpoint of biology, an objective is to elucidate some of the general dynamical features that affect the disposition of an entire cell, cell colonies and tissues. Conventionally averaged field variables of continuum mechanics are used to describe the overall global effects which result from the myriad of small scale molecular interactions. An attempt is made to establish cause and effect relationships from correct dynamical laws of motion rather than by what may have been unnecessary invocation of metabolic or life processes. Several topics are discussed where there are strong analogies droplets and cells including: encapsulated droplets/cell membranes; droplet shape/cell shape; adhesion and spread of a droplet/cell motility and adhesion; and oams and multiphase flows/cell aggregates and tissues. Evidence is presented to show that certain concepts of continuum theory such as suface tension, surface free energy, contact angle, bending moments, etc. are relevant and applicable to the study of cell biology.

  7. Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    James E. O' Brien

    2012-03-01

    Hydrogen can be produced from water splitting with relatively high efficiency using high temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high temperature process heat. The overall thermal-to-hydrogen efficiency for high temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. An overview of high temperature electrolysis technology will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.

  8. Simulation of transient transport phenomena in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, H.; Li, X. [Waterloo Univ., ON (Canada); Berg, P. [Univ. of Ontario Inst. of Technology, Oshawa, ON (Canada)

    2009-07-01

    Most modelling studies characterize the dynamic performance of the proton exchange membrane fuel cells (PEMFCs) by the gas diffusion, membrane hydration/dehydration and heat transfer processes. This study involved a comprehensive examination of the transport phenomena through a newly developed 3D unsteady model. The study revealed that the dynamic response of a PEMFC is determined by a combination of 7 transient transport mechanisms, notably (1) the non-equilibrium phase transfer between the liquid water and water vapor (condensation/evaporation), (2) the non-equilibrium membrane water sorption/desorption, (3) water transport within the bulk membrane (membrane hydration/dehydration), (4) liquid water transport in the porous backing layer, (5) heat transfer, (6) gas diffusion towards the reacting site, and (7) the convective gas flow in the gas channel. Several case studies have investigated the dynamic response of the cell corresponding to some typical operating condition changes, such as step changes of the cell voltage, relative humidity, inlet gas pressure and stoichiometric ratio for both co-flow and counter-flow configurations.

  9. Cell volume regulation: physiology and pathophysiology

    DEFF Research Database (Denmark)

    Lambert, I H; Hoffmann, E K; Pedersen, Stine Helene Falsig

    2008-01-01

    not only under physiological conditions, e.g. following accumulation of nutrients, during epithelial absorption/secretion processes, following hormonal/autocrine stimulation, and during induction of apoptosis, but also under pathophysiological conditions, e.g. hypoxia, ischaemia and hyponatremia....../hypernatremia. On the other hand, it has recently become clear that an increase or reduction in cell volume can also serve as a specific signal in the regulation of physiological processes such as transepithelial transport, cell migration, proliferation and death. Although the mechanisms by which cell volume perturbations...... are sensed are still far from clear, significant progress has been made with respect to the nature of the sensors, transducers and effectors that convert a change in cell volume into a physiological response. In the present review, we summarize recent major developments in the field, and emphasize...

  10. Numerical modeling transport phenomena in proton exchange membrane fuel cells

    Science.gov (United States)

    Suh, DongMyung

    To study the coupled phenomena occurring in proton exchange membrane fuel cells, a two-phase, one-dimensional, non-isothermal model is developed in the chapter 1. The model includes water phase change, proton transport in the membrane and electro-osmotic effect. The thinnest, but most complex layer in the membrane electrode assembly, catalyst layer, is considered an interfacial boundary between the gas diffusion layer and the membrane. Mass and heat transfer and electro-chemical reaction through the catalyst layer are formulated into equations, which are applied to boundary conditions for the gas diffusion layer and the membrane. Detail accounts of the boundary equations and the numerical solving procedure used in this work are given. The polarization curve is calculated at different oxygen pressures and compared with the experimental results. When the operating condition is changed along the polarization curve, the change of physicochemical variables in the membrane electrode assembly is studied. In particular, the over-potential diagram presents the usage of the electrochemical energy at each layer of the membrane electrode assembly. Humidity in supplying gases is one of the most important factors to consider for improving the performance of PEMFE. Both high and low humidity conditions can result in a deteriorating cell performance. The effect of humidity on the cell performance is studied in the chapter 2. First, a numerical model based on computational fluid dynamics is developed. Second, the cell performances are simulated, when the relative humidity is changed from 0% to 100% in the anode and the cathode channel. The simulation results show how humidity in the reactant gases affects the water content distribution in the membrane, the over-potential at the catalyst layers and eventually the cell performance. In particular, the rapid enhancement in the cell performance caused by self-hydrating membrane is captured by the simulation. Fully humidifying either H2

  11. Physiological Maturation of Regenerating Hair Cells

    Science.gov (United States)

    Baird, Richard A.

    2003-01-01

    between ion channel clustering and synaptic formation in hair cells and afferent neurons. In future studies, we will determine when hair cell precursors acquire electrical tuning, and, using whole-cell patch-clamp techniques, identify and characterize their L-VGCC and BK currents. We will also use biophysical techniques to determine the number of L-VGCC and BK channels and the size and gating kinetics of their underlying L-VGCC and BK conductances, correlating these variables with the amplitude and frequency of membrane oscillations produced by intracellular current steps. We expect these studies to determine how hair cells regulate ion channel expression to achieve specific physiological responses.

  12. Mass transport phenomena in direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, T.S.; Xu, C.; Chen, R.; Yang, W.W. [Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR (China)

    2009-06-15

    Clean and highly efficient energy production has long been sought to solve energy and environmental problems. Fuel cells, which convert the chemical energies stored in fuel directly into electrical energy, are expected to be a key enabling technology for this century. This article is concerned with one of the most advanced fuel cells - direct methanol fuel cells (DMFCs). We present a comprehensive review of the state-of-the-art studies of mass transport of different species, including the reactants (methanol, oxygen and water) and the products (water and carbon dioxide) in DMFCs. Rather than elaborating on the details of the previous numerical modeling and simulation, the article emphasizes: (1) the critical mass-transport issues that need to be addressed so that the performance and operating stability of DMFCs can be upgraded, (2) the basic mechanisms that control the mass-transport behaviors of reactants and products in this type of fuel cell, and (3) the previous experimental and numerical findings regarding the correlation between the mass transport of each species and cell performance. (author)

  13. Comparison of molecular mechanisms mediating cell contact phenomena in model developmental systems: an exploration of universality.

    Science.gov (United States)

    Bowers-Morrow, Vivienne M; Ali, Sinan O; Williams, Keith L

    2004-08-01

    Are there universal molecular mechanisms associated with cell contact phenomena during metazoan ontogenesis? Comparison of adhesion systems in disparate model systems indicates the existence of unifying principles. Requirements for multicellularity are (a) the construction of three-dimensional structures involving a crucial balance between adhesiveness and motility; and (b) the establishment of integration at molecular, cellular, tissue, and organismal levels of organization. Mechanisms for (i) cell-cell and cell-substrate adhesion, (ii) cell movement, (iii) cell-cell communication, (iv) cellular responses, (v) regulation of these processes, and (vi) their integration with patterning, growth, and other developmental processes are all crucial to metazoan development, and must have been present for the emergence and radiation of Metazoa. The principal unifying themes of this review are the dynamics and regulation of cell contact phenomena. Our knowledge of the dynamic molecular mechanisms underlying cell contact phenomena remains fragmentary. Here we examine the molecular bases of cell contact phenomena using extant model developmental systems (representing a wide range of phyla) including the simplest i.e. sponges, and the eukaryotic protist Dictyostelium discoideum, the more complex Drosophila melanogaster, and vertebrate systems. We discuss cell contact phenomena in a broad developmental context. The molecular language of cell contact phenomena is complex; it involves a plethora of structurally and functionally diverse molecules, and diverse modes of intermolecular interactions mediated by protein and/or carbohydrate moieties. Reasons for this are presumably the necessity for a high degree of specificity of intermolecular interactions, the requirement for a multitude of different signals, and the apparent requirement for an increasingly large repertoire of cell contact molecules in more complex developmental systems, such as the developing vertebrate nervous

  14. Glial cells in (patho)physiology

    Science.gov (United States)

    Parpura, Vladimir; Heneka, Michael T.; Montana, Vedrana; Oliet, Stéphane H.R.; Schousboe, Arne; Haydon, Philip. G.; Stout, Randy F.; Spray, David C.; Reichenbach, Andreas; Pannicke, Thomas; Pekny, Milos; Pekna, Marcela; Zorec, Robert; Verkhratsky, Alexei

    2012-01-01

    Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca2+ signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca2+-dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer’s disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review sheds new light on the brain operation in health and disease, but also points to many unknowns. PMID:22251135

  15. Transport phenomena in alkaline direct ethanol fuel cells for sustainable energy production

    Science.gov (United States)

    An, L.; Zhao, T. S.

    2017-02-01

    Alkaline direct ethanol fuel cells (DEFC), which convert the chemical energy stored in ethanol directly into electricity, are one of the most promising energy-conversion devices for portable, mobile and stationary power applications, primarily because this type of fuel cell runs on a carbon-neutral, sustainable fuel and the electrocatalytic and membrane materials that constitute the cell are relatively inexpensive. As a result, the alkaline DEFC technology has undergone a rapid progress over the last decade. This article provides a comprehensive review of transport phenomena of various species in this fuel cell system. The past investigations into how the design and structural parameters of membrane electrode assemblies and the operating parameters affect the fuel cell performance are discussed. In addition, future perspectives and challenges with regard to transport phenomena in this fuel cell system are also highlighted.

  16. Using measures of single-cell physiology and physiological state to understand organismic aging.

    Science.gov (United States)

    Mendenhall, Alexander; Driscoll, Monica; Brent, Roger

    2016-02-01

    Genetically identical organisms in homogeneous environments have different lifespans and healthspans. These differences are often attributed to stochastic events, such as mutations and 'epimutations', changes in DNA methylation and chromatin that change gene function and expression. But work in the last 10 years has revealed differences in lifespan- and health-related phenotypes that are not caused by lasting changes in DNA or identified by modifications to DNA or chromatin. This work has demonstrated persistent differences in single-cell and whole-organism physiological states operationally defined by values of reporter gene signals in living cells. While some single-cell states, for example, responses to oxygen deprivation, were defined previously, others, such as a generally heightened ability to make proteins, were, revealed by direct experiment only recently, and are not well understood. Here, we review technical progress that promises to greatly increase the number of these measurable single-cell physiological variables and measureable states. We discuss concepts that facilitate use of single-cell measurements to provide insight into physiological states and state transitions. We assert that researchers will use this information to relate cell level physiological readouts to whole-organism outcomes, to stratify aging populations into groups based on different physiologies, to define biomarkers predictive of outcomes, and to shed light on the molecular processes that bring about different individual physiologies. For these reasons, quantitative study of single-cell physiological variables and state transitions should provide a valuable complement to genetic and molecular explanations of how organisms age. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  17. Characterization of transport phenomena in small polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Himanen, O.P.

    2008-07-01

    In small fuel cell systems, energy consumption and size of auxiliary devices should be minimized. One option is to use passive controlling methods that rely on material and structural solutions. Therefore it is important to understand transport phenomena occurring in the cells. In this thesis, charge, mass, and heat transport phenomena related to small PEMFCs were studied experimentally and by modeling. A new method was developed for the characterization of water transport properties of polymer electrolyte membrane under realistic operating conditions. The method was used to evaluate the diffusion coefficient of water in the membrane. Due to channelrib structure, cell components are inhomogeneously compressed. Charge and mass transport parameters were experimentally evaluated as a function of compression. The effect of inhomogeneous compression on cell operation was studied by modeling. Inhomogeneous compression does not significantly affect the polarization behavior of the cell, but it creates uneven current and temperature distributions inside the cell. This affects both cell performance and lifetime and should not be ignored in cell design and modeling. The operation of a freebreathing PEMFC was studied at subzero temperatures. To be able to operate at low temperatures, current density must be high enough to avoid freezing of reactant product water inside the cell. Startup at cold temperatures requires active heating. To maximize fuel efficiency, the operation of a freebreathing PEMFC in dead end mode was investigated. Dead ended operation with periodic purging enables high fuel utilization rate and the test cell operated without significant water management problems or performance loss. (orig.)

  18. Physiological alterations in UV-irradiated cells: liquid holding recovery

    International Nuclear Information System (INIS)

    Aragao, B.R.

    1980-01-01

    The biochemical and physiological alterations that occur in ultraviolet irradiated cells, during liquid holding have been studied. Incubation in buffer acts not to interfer directly with the mechanic repairs but by promoting metabolic alterations that would block some irreversible and lethal physiological responses. (L.M.J.) [pt

  19. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39 (Iraq)

    2013-07-01

    Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport in micro PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize the micro fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a micro proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a micro PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

  20. Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

    Science.gov (United States)

    Xu, Ao; Shyy, Wei; Zhao, Tianshou

    2017-06-01

    Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

  1. A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

    Science.gov (United States)

    Baldwin, Richard S.; Bennett, William R.

    2007-01-01

    The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

  2. Physiological significance of ECL-cell histamine.

    OpenAIRE

    Andersson, K.; Chen, D.; Mattsson, H.; Sundler, F.; Håkanson, R.

    1998-01-01

    In the oxyntic mucosa of the mammalian stomach, histamine is stored in ECL cells and in mucosal mast cells. In the rat, at least 80 percent of oxyntic mucosal histamine resides in the ECL cells. Histamine is a key factor in the regulation of gastric acid secretion. Following depletion of ECL-cell histamine by treatment with alpha-fluoromethylhistidine (alpha-FMH), basal acid secretion was reduced, and gastrin-stimulated acid secretion was abolished. Vagally-induced acid secretion (by insulin ...

  3. Review on modeling development for multiscale chemical reactions coupled transport phenomena in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Martin; Yuan, Jinliang; Sunden, Bengt [Department of Energy Sciences, Lund University, SE-221 00 Lund (Sweden)

    2010-05-15

    A literature study is performed to compile the state-of-the-art, as well as future potential, in SOFC modeling. Principles behind various transport processes such as mass, heat, momentum and charge as well as for electrochemical and internal reforming reactions are described. A deeper investigation is made to find out potentials and challenges using a multiscale approach to model solid oxide fuel cells (SOFCs) and combine the accuracy at microscale with the calculation speed at macroscale to design SOFCs, based on a clear understanding of transport phenomena, chemical reactions and functional requirements. Suitable methods are studied to model SOFCs covering various length scales. Coupling methods between different approaches and length scales by multiscale models are outlined. Multiscale modeling increases the understanding for detailed transport phenomena, and can be used to make a correct decision on the specific design and control of operating conditions. It is expected that the development and production costs will be decreased and the energy efficiency be increased (reducing running cost) as the understanding of complex physical phenomena increases. It is concluded that the connection between numerical modeling and experiments is too rare and also that material parameters in most cases are valid only for standard materials and not for the actual SOFC component microstructures. (author)

  4. Collective Phenomena in Kidney Autoregulation

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Sosnovtseva, Olga; Holstein-Rathlou, N.-H.

    2004-01-01

    By controling the excretion of water and salts, the kidneys play all important role ill regulating the blood pressure and maintaining a proper environment for the cells of the body. This control depends to a large extent oil mechanisms that are associated with the individual functional unit...... for the observed synchronization phenomena, and discuss the possible physiological significance of these phenomena. We are particularly interested ill synchronization effects that call occur among neighboring nephrons that individually display irregular (or chaotic) dynamics in their pressure and flow regulation....

  5. Numerical simulation of mass and energy transport phenomena in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Arpino, F. [Dipartimento di Meccanica, Strutture, Ambiente e Territorio (DiMSAT), University of Cassino, via Di Biasio 43, Cassino (Italy); Massarotti, N. [Dipertimento per le Tecnologie (DiT), University of Naples ' ' Parthenope' ' , Centro Direzionale, isola C4, 80143 Napoli (Italy)

    2009-12-15

    Solid Oxide Fuel Cells (SOFCs) represent a very promising technology for near future energy conversion thanks to a number of advantages, including the possibility of using different fuels. In this paper, a detailed numerical model, based on a general mathematical description and on a finite element Characteristic based Split (CBS) algorithm code is employed to simulate mass and energy transport phenomena in SOFCs. The model predicts the thermodynamic quantity of interest in the fuel cell. Full details of the numerical solution obtained are presented both in terms of heat and mass transfer in the cell and in terms of electro-chemical reactions that occur in the system considered. The results obtained with the present algorithm is compared with the experimental data available in the literature for validation, showing an excellent agreement. (author)

  6. Physiology

    Science.gov (United States)

    Kay, Ian

    2008-01-01

    Underlying recent developments in health care and new treatments for disease are advances in basic medical sciences. This edition of "Webwatch" focuses on sites dealing with basic medical sciences, with particular attention given to physiology. There is a vast amount of information on the web related to physiology. The sites that are included here…

  7. Transport phenomena within the porous cathode for a proton exchange membrane fuel cell

    Science.gov (United States)

    Liu, Juanfang; Oshima, Nobuyuki; Kurihara, Eru; Saha, Litan Kumar

    A two-phase, one-dimensional steady model is developed to analyze the coupled phenomena of cathode flooding and mass-transport limiting for the porous cathode electrode of a proton exchange membrane fuel cell. In the model, the catalyst layer is treated not as an interface between the membrane and gas diffusion layer, but as a separate computational domain with finite thickness and pseudo-homogenous structure. Furthermore, the liquid water transport across the porous electrode is driven by the capillary force based on Darcy's law. And the gas transport is driven by the concentration gradient based on Fick's law. Additionally, through Tafel kinetics, the transport processes of gas and liquid water are coupled. From the numerical results, it is found that although the catalyst layer is thin, it is very crucial to better understand and more correctly predict the concurrent phenomena inside the electrode, particularly, the flooding phenomena. More importantly, the saturation jump at the interface of the gas diffusion layer and catalyst layers is captured, when the continuity of the capillary pressure is imposed on the interface. Elsewise, the results show further that the flooding phenomenon in the CL is much more serious than that in the GDL, which has a significant influence on the mass transport of the reactants. Moreover, the saturation level inside the cathode is determined, to a great extent, by the surface overpotential, the absolute permeability of the porous electrode, and the boundary value of saturation at the gas diffusion layer-gas channel interface. In order to prevent effectively flooding, it should remove firstly the liquid water accumulating inside the CL and keep the boundary value of liquid saturation as low as possible.

  8. Transport phenomena within the porous cathode for a proton exchange membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Juanfang; Oshima, Nobuyuki; Kurihara, Eru; Saha, Litan Kumar [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

    2010-10-01

    A two-phase, one-dimensional steady model is developed to analyze the coupled phenomena of cathode flooding and mass-transport limiting for the porous cathode electrode of a proton exchange membrane fuel cell. In the model, the catalyst layer is treated not as an interface between the membrane and gas diffusion layer, but as a separate computational domain with finite thickness and pseudo-homogenous structure. Furthermore, the liquid water transport across the porous electrode is driven by the capillary force based on Darcy's law. And the gas transport is driven by the concentration gradient based on Fick's law. Additionally, through Tafel kinetics, the transport processes of gas and liquid water are coupled. From the numerical results, it is found that although the catalyst layer is thin, it is very crucial to better understand and more correctly predict the concurrent phenomena inside the electrode, particularly, the flooding phenomena. More importantly, the saturation jump at the interface of the gas diffusion layer and catalyst layers is captured, when the continuity of the capillary pressure is imposed on the interface. Elsewise, the results show further that the flooding phenomenon in the CL is much more serious than that in the GDL, which has a significant influence on the mass transport of the reactants. Moreover, the saturation level inside the cathode is determined, to a great extent, by the surface overpotential, the absolute permeability of the porous electrode, and the boundary value of saturation at the gas diffusion layer-gas channel interface. In order to prevent effectively flooding, it should remove firstly the liquid water accumulating inside the CL and keep the boundary value of liquid saturation as low as possible. (author)

  9. Cell Physiology and Interactions of Biomaterials and Matrices

    Czech Academy of Sciences Publication Activity Database

    Hunkeler, D.; Vaňková, Radomíra

    2003-01-01

    Roč. 28, č. 6 (2003), s. 193-197 ISSN 0032-3918 R&D Projects: GA MŠk OC 840.20 Institutional research plan: CEZ:AV0Z5038910 Keywords : Biomaterials * Cell physiology * Encapsulation Subject RIV: CE - Biochemistry

  10. Macroscopic analysis of characteristic water transport phenomena in polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hye-Mi [Graduate School, Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea); Lee, Kwan-Soo; Um, Sukkee [School of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea)

    2008-04-15

    Comprehensive analytical and numerical analyses were performed, focusing on anode water loss, cathode flooding, and water equilibrium for polymer electrolyte fuel cells. General features of water transport as a function of membrane thickness and current density were presented to illustrate the net effect of back-diffusion of water from the cathode to anode over a polymer electrolyte fuel cell domain. First, two-dimensional numerical simulation were performed, showing that the difference in molar concentration of water at the channel outlet is widened as the operating current density increases with a thin membrane (Nafion {sup registered} 111), which was verified by Dong et al. [Distributed performance of polymer electrolyte fuel cells under low-humidity conditions. J Electrochem Soc 2005; 152: A2114-22]. Then, analytical solutions were compared with computational results in predicting those characteristics of water transport phenomena. It was theoretically estimated that the high pressure operation of fuel cells expedites water condensing and results in shorter anode water loss and cathode flooding locations. In this study, it was also found that a thin membrane (Nafion {sup registered} 111) facilitates water transport in the through-membrane direction and therefore water concentration at the anode and cathode channel outlets reaches an equilibrium state particularly at low operating current densities. Moreover, the difference in the anode water concentration between Nafion {sup registered} 111 and Nafion {sup registered} 115 membranes becomes intensified in the in-plane direction under the same water production condition, while the cathode water concentration profiles remains almost same. (author)

  11. pH Homeostasis Linked with Capacitance Relaxation Phenomena and Electrostrictive Energy in Cancer Cells

    Directory of Open Access Journals (Sweden)

    T. K. Basak

    2009-10-01

    Full Text Available The present paper describes the capacitance relaxation phenomenon linked with the metastasis of cancer cells (US Patent No. TK Basak 5691178, 1997.The capacitance relaxation phenomenon is so significant that it can be correlated with the pH homeostasis and the electrostrictive energy of the cancer cells. The electrostrictive phenomenon is due to the composite dielectric property of the cancer cell concomitant with the capacitance relaxation phenomena. It is to be noted that pH homeostats in cancer cells are directly linked with the gene homeostat in a novel way so far as dephosphorylation of the oncogenes is concerned. This phenomenon in respect of pH homeostasis has been correlated with capacitance relaxation phenomenon and electrostrictive energy during pH mediated signal transduction phase. For this correlation DTREG has been used for the implementation of Datamining. For this analysis the type of model used in datamining is single tree for which the input data comprises of target and predictor variables. From the datamining result it is possible to conclude that the pH range (acidic for all types of cancer is not unique and as such cancer has distinct specificity in respect of pH homeostasis.

  12. Three-dimensional numerical study on cell performance and transport phenomena of PEM fuel cells with conventional flow fields

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jer-Huan [Department of Mechanical Engineering, Northern Taiwan Institute of Science and Technology, Beitou, Taipei 11202 (China); Yan, Wei-Mon; Li, Hung-Yi; Tsai, Wei-Che [Department of Mechatronic Engineering, Huafan University, Shih-Ting, Taipei 22305 (China)

    2008-01-15

    In this paper, a three-dimensional numerical model of the proton exchange membrane fuel cells (PEMFCs) with conventional flow field designs (parallel flow field, Z-type flow field, and serpentine flow field) has been established to investigate the performance and transport phenomena in the PEMFCs. The influences of the flow field designs on the fuel utilization, the water removal, and the cell performance of the PEMFC are studied. The distributions of velocity, oxygen mass fraction, current density, liquid water, and pressure with the convention flow fields are presented. For the conventional flow fields, the cell performance can be enhanced by adding the corner number, increasing the flow channel length, and decreasing the flow channel number. The cell performance of the serpentine flow field is the best, followed by the Z-type flow field and then the parallel flow field. (author)

  13. Experimental study and modeling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh; Andreasen, Søren Juhl; Rasmussen, Peder Lund

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modeling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing the d...

  14. Transport phenomena during freezing of adipose tissue derived adult stem cells.

    Science.gov (United States)

    Thirumala, Sreedhar; Gimble, Jeffrey M; Devireddy, Ram V

    2005-11-05

    In the present study a well-established differential scanning calorimeter (DSC) technique is used to measure the water transport phenomena during freezing of stromal vascular fraction (SVF) and adipose tissue derived adult stem (ADAS) cells at different passages (Passages 0 and 2). Volumetric shrinkage during freezing of adipose derived cells was obtained at a cooling rate of 20 degrees C/min in the presence of extracellular ice and two different, commonly used, cryoprotective agents, CPAs (10% DMSO and 10% Glycerol). The adipose derived cells were modeled as spheres of 50 microm diameter with an osmotically inactive volume (Vb) of 0.6Vo, where Vo is the isotonic cell volume. By fitting a model of water transport to the experimentally obtained volumetric shrinkage data, the "best-fit" membrane permeability parameters (reference membrane permeability to water, Lpg or Lpg[cpa] and the activation energy, ELp or ELp[cpa]) were determined. The "best-fit" membrane permeability parameters for adipose derived cells in the absence and presence of CPAs ranged from: Lpg=23.1-111.5x10(-15) m3/Ns (0.135-0.652 microm/min-atm) and ELp=43.1-168.8 kJ/mol (9.7-40.4 kcal/mol). Numerical simulations of water transport were then performed under a variety of cooling rates (5-100 degrees C/min) using the experimentally determined membrane permeability parameters. And finally, the simulation results were analyzed to predict the optimal rates of freezing adipose derived cells in the presence and absence of CPAs. Copyright (c) 2005 Wiley Periodicals, Inc.

  15. Cell volume regulation in epithelial physiology and cancer

    DEFF Research Database (Denmark)

    Pedersen, Stine Helene Falsig; Hoffmann, Else Kay; Novak, Ivana

    2013-01-01

    such as cancer, transepithelial and cell volume regulatory ion transport are dys-regulated. Furthermore, epithelial architecture and coordinated ion transport function are lost, cell survival/death balance is altered, and new interactions with the stroma arise, all contributing to drug resistance. Since altered...... expression of ion transporters and channels is now recognized as one of the hallmarks of cancer, it is timely to consider this especially for epithelia. Epithelial cells are highly proliferative and epithelial cancers, carcinomas, account for about 90% of all cancers. In this review we will focus on ion...... transporters and channels with key physiological functions in epithelia and known roles in the development of cancer in these tissues. Their roles in cell survival, cell cycle progression, and development of drug resistance in epithelial cancers will be discussed....

  16. Local transport phenomena and cell performance of PEM fuel cells with various serpentine flow field designs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Dong [Department of Thermal Engineering, School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Duan, Yuan-Yuan [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China); Yan, Wei-Mon [Department of Mechatronic Engineering, Huafan University, Taipei 22305 (China); Peng, Xiao-Feng [Laboratory of Phase Change and Interfacial Transport Phenomena, Tsinghua University, Beijing 100084 (China)

    2008-01-03

    The flow field design in bipolar plates is very important for improving reactant utilization and liquid water removal in proton exchange membrane fuel cells (PEMFCs). A three-dimensional model was used to analyze the effect of the design parameters in the bipolar plates, including the number of flow channel bends, number of serpentine flow channels and the flow channel width ratio, on the cell performance of miniature PEMFCs with the serpentine flow field. The effect of the liquid water formation on the porosities of the porous layers was also taken into account in the model while the complex two-phase flow was neglected. The predictions show that (1) for the single serpentine flow field, the cell performance improves as the number of flow channel bends increases; (2) the single serpentine flow field has better performance than the double and triple serpentine flow fields; (3) the cell performance only improves slowly as the flow channel width increases. The effects of these design parameters on the cell performance were evaluated based on the local oxygen mass flow rates and liquid water distributions in the cells. Analysis of the pressure drops showed that for these miniature PEMFCs, the energy losses due to the pressure drops can be neglected because they are far less than the cell output power. (author)

  17. PIXE microanalysis in human cells: physiology and pharmacology

    International Nuclear Information System (INIS)

    Moretto, P.; Llabador, Y.; Ortega, R.; Simonoff, M.; Razafindrabe, L.

    1993-01-01

    The micro-PIXE technique has been regularly carried out for more than two years to provide elemental distributions in human cells. Using this technique in the framework of cellular biology, two research axes have been developed: The cellular pharmacology of chemotherapeutic agents and the physiology of ionic cellular exchanges. These studies are based upon in vitro experimental models of human cells, either under the form of isolated cultured cells or as part of well-structured tissues. The aim of this paper is to present the experimental procedures and methodological aspects of cellular and subcellular quantitative mapping. Cell processing, identification of intracellular structures, quantitatives results and beam damage will be discussed and illustrated by examples issuing from the above-mentioned studies. (orig.)

  18. Phospholipases of Mineralization Competent Cells and Matrix Vesicles: Roles in Physiological and Pathological Mineralizations

    Directory of Open Access Journals (Sweden)

    René Buchet

    2013-03-01

    Full Text Available The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM, or

  19. Phospholipases of Mineralization Competent Cells and Matrix Vesicles: Roles in Physiological and Pathological Mineralizations

    Science.gov (United States)

    Mebarek, Saida; Abousalham, Abdelkarim; Magne, David; Do, Le Duy; Bandorowicz-Pikula, Joanna; Pikula, Slawomir; Buchet, René

    2013-01-01

    The present review aims to systematically and critically analyze the current knowledge on phospholipases and their role in physiological and pathological mineralization undertaken by mineralization competent cells. Cellular lipid metabolism plays an important role in biological mineralization. The physiological mechanisms of mineralization are likely to take place in tissues other than in bones and teeth under specific pathological conditions. For instance, vascular calcification in arteries of patients with renal failure, diabetes mellitus or atherosclerosis recapitulates the mechanisms of bone formation. Osteoporosis—a bone resorbing disease—and rheumatoid arthritis originating from the inflammation in the synovium are also affected by cellular lipid metabolism. The focus is on the lipid metabolism due to the effects of dietary lipids on bone health. These and other phenomena indicate that phospholipases may participate in bone remodelling as evidenced by their expression in smooth muscle cells, in bone forming osteoblasts, chondrocytes and in bone resorbing osteoclasts. Among various enzymes involved, phospholipases A1 or A2, phospholipase C, phospholipase D, autotaxin and sphingomyelinase are engaged in membrane lipid remodelling during early stages of mineralization and cell maturation in mineralization-competent cells. Numerous experimental evidences suggested that phospholipases exert their action at various stages of mineralization by affecting intracellular signaling and cell differentiation. The lipid metabolites—such as arachidonic acid, lysophospholipids, and sphingosine-1-phosphate are involved in cell signaling and inflammation reactions. Phospholipases are also important members of the cellular machinery engaged in matrix vesicle (MV) biogenesis and exocytosis. They may favour mineral formation inside MVs, may catalyse MV membrane breakdown necessary for the release of mineral deposits into extracellular matrix (ECM), or participate in

  20. Gold nanoparticle interactions with endothelial cells cultured under physiological conditions.

    Science.gov (United States)

    Freese, C; Anspach, L; Deller, R C; Richards, S-J; Gibson, M I; Kirkpatrick, C J; Unger, R E

    2017-03-28

    PEGylated gold nanoparticles (AuNPs) have an extended circulation time after intravenous injection in vivo and exhibit favorable properties for biosensing, diagnostic imaging, and cancer treatment. No impact of PEGylated AuNPs on the barrier forming properties of endothelial cells (ECs) has been reported, but recent studies demonstrated that unexpected effects on erythrocytes are observed. Almost all studies to date have been with static-cultured ECs. Herein, ECs maintained under physiological cyclic stretch and flow conditions and used to generate a blood-brain barrier model were exposed to 20 nm PEGylated AuNPs. An evaluation of toxic effects, cell stress, the release profile of pro-inflammatory cytokines, and blood-brain barrier properties showed that even under physiological conditions no obvious effects of PEGylated AuNPs on ECs were observed. These findings suggest that 20 nm-sized, PEGylated AuNPs may be a useful tool for biomedical applications, as they do not affect the normal function of healthy ECs after entering the blood stream.

  1. Physiological and pathophysiological functions of intestinal mast cells.

    Science.gov (United States)

    Bischoff, Stephan C

    2009-07-01

    The normal gastrointestinal (GI) mucosa is equipped with mast cells that account for 2-3% of lamina propria cells under normal conditions. Mast cells are generally associated with allergic disease, and indeed, food allergy that manifests in the GI tract is usually mast cell dependent. On the other hand, mast cells have a number of physiological functions in the GI tract, namely regulatory functions such as control of blood flow and coagulation, smooth muscle contraction and peristalsis, and secretion of acid, electrolytes, and mucus by epithelial cells. One of the most intriguing functions of intestinal mast cells is their role in host defense against microbes like bacteria, viruses, or parasites. Mast cells recognize microbes by antibody-dependent mechanisms and through pattern-recognition receptors. They direct the subsequent immune response by attracting both granulocytes and lymphocytes to the site of challenge via paracrine cytokine release. Moreover, mast cells initiate, by releasing proinflammatory mediators, innate defense mechanisms such as enhanced epithelial secretion, peristalsis, and alarm programs of the enteric nervous This initiation can occur in response to a primary contact to the microbe or other danger signals, but becomes much more effective if the triggering antigen reappears and antibodies of the IgE or IgG type have been generated in the meantime by the specific immune system. Thus, mast cells operate at the interface between innate and adaptive immune responses to enhance the defense against pathogens and, most likely, the commensal flora. In this respect, it is important to note that mast cells are directly involved in controlling the function of the intestinal barrier that turned out to be a crucial site for the development of infectious and immune-mediated diseases. Hence, intestinal mast cells perform regulatory functions to maintain tissue homeostasis, they are involved in host defense mechanisms against pathogens, and they can induce

  2. A three-dimensional mixed-domain PEM fuel cell model with fully-coupled transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Hua [Center for Engineering and Scientific Computation, College of Computer Science, P.O. Box 1455, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2007-02-10

    A three-dimensional mixed-domain PEM fuel cell model with fully-coupled transport phenomena has been developed in this paper. In this model, after fully justified simplifications, only one set of interfacial boundary conditions is required to connect the water content equation inside the membrane and the equation of the water mass fraction in the other regions. All the other conservation equations are still solved in the single-domain framework. Numerical results indicate that although the fully-coupled transport phenomena produce only minor effects on the overall PEM fuel cell performance, i.e. average current density, they impose significant effects on current distribution, net water transfer coefficient, velocity and density variations, and species distributions. Intricate interactions of the mass transfer across the membrane, electrochemical kinetics, density and velocity variations, and species distributions dictate the detailed cell performances. Therefore, for accurate PEM fuel cell modeling and simulation, the effects of the fully-coupled transport phenomena could not be neglected. (author)

  3. Experimental study and modelling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modelling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing...... the degradation caused by these phenomena, is suggested. Using the proposed model, information about optimum operational temperatures is derived. To investigate how the degradation propagates on stack level, a simplified stack model is developed. The model is 1-dimensional, non-isothermal, and semi......-transient (considering degradation with time). The model shows that the degradation in a stack will not progress uniformly, but occurs faster in the hot end of the stack. Furthermore, the model shows that the degradation is very dependent on stack temperature control scheme. Two experiments were conducted; a 500 hours...

  4. Direct determination of phosphatase activity from physiological substrates in cells.

    Directory of Open Access Journals (Sweden)

    Zhongyuan Ren

    Full Text Available A direct and continuous approach to determine simultaneously protein and phosphate concentrations in cells and kinetics of phosphate release from physiological substrates by cells without any labeling has been developed. Among the enzymes having a phosphatase activity, tissue non-specific alkaline phosphatase (TNAP performs indispensable, multiple functions in humans. It is expressed in numerous tissues with high levels detected in bones, liver and neurons. It is absolutely required for bone mineralization and also necessary for neurotransmitter synthesis. We provided the proof of concept that infrared spectroscopy is a reliable assay to determine a phosphatase activity in the osteoblasts. For the first time, an overall specific phosphatase activity in cells was determined in a single step by measuring simultaneously protein and substrate concentrations. We found specific activities in osteoblast like cells amounting to 116 ± 13 nmol min(-1 mg(-1 for PPi, to 56 ± 11 nmol min(-1 mg(-1 for AMP, to 79 ± 23 nmol min(-1 mg(-1 for beta-glycerophosphate and to 73 ± 15 nmol min(-1 mg(-1 for 1-alpha-D glucose phosphate. The assay was also effective to monitor phosphatase activity in primary osteoblasts and in matrix vesicles. The use of levamisole--a TNAP inhibitor--served to demonstrate that a part of the phosphatase activity originated from this enzyme. An IC50 value of 1.16 ± 0.03 mM was obtained for the inhibition of phosphatase activity of levamisole in osteoblast like cells. The infrared assay could be extended to determine any type of phosphatase activity in other cells. It may serve as a metabolomic tool to monitor an overall phosphatase activity including acid phosphatases or other related enzymes.

  5. Thermogenic adipocytes: from cells to physiology and medicine.

    Science.gov (United States)

    Diaz, Mauricio Berriel; Herzig, Stephan; Vegiopoulos, Alexandros

    2014-10-01

    The identification of active brown fat in humans has evoked widespread interest in the biology of non-shivering thermogenesis among basic and clinical researchers. As a consequence we have experienced a plethora of contributions related to cellular and molecular processes in thermogenic adipocytes as well as their function in the organismal context and their relevance to human physiology. In this review we focus on the cellular basis of non-shivering thermogenesis, particularly in relation to human health and metabolic disease. We provide an overview of the cellular function and distribution of thermogenic adipocytes in mouse and humans, and how this can be affected by environmental factors, such as prolonged cold exposure. We elaborate on recent evidence and open questions on the distinction of classical brown versus beige/brite adipocytes. Further, the origin of thermogenic adipocytes as well as current models for the recruitment of beige/brite adipocytes is discussed with an emphasis on the role of progenitor cells. Focusing on humans, we describe the expanding evidence for the activity, function and physiological relevance of thermogenic adipocytes. Finally, as the potential of thermogenic adipocyte activation as a therapeutic approach for the treatment of obesity and associated metabolic diseases becomes evident, we highlight goals and challenges for current research on the road to clinical translation. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Investigation of nanostructured electrocatalysts and mass transport phenomena in polymer electrolyte fuel cells

    Science.gov (United States)

    Goenaga, Gabriel A.

    Proton exchange membrane (PEM) fuel cells (FC) are promising devices in the search of clean and efficient technologies to reduce the use of fossil fuels. However, their poor performance in dynamic applications and high cost of platinum group metal (PGM) catalysts, have prevented them from becoming an affordable solution. This dissertation comprehend three research projects that study the mass transport phenomena in modified PEMs, the reduction of the amount of PGM catalyst used for oxygen reduction reaction (ORR) and the use of non-PGM catalysts as alternative catalyst to Pt for ORR. Nafion is the most used PEM for FC applications. Nafion proton conductivity is proportional to its degree of hydration, what imposes low temperature operation to maintain appropriate water content. In this research, Nafion composite membranes doped with hydrophilic metal inorganic particles have been studied using pulse field gradient (PFG) nuclear magnetic resonance (NMR). The Nafion composite membranes were found to have higher water uptake, higher water retention, higher water diffusion and, in some cases, lower methanol diffusion (crossover) than the filler free Nafion membrane. The amount of Pt and PGM catalysts supported on carbon used in the electrodes, has a great impact in the PEMFC cost. In particular, it is of high relevance to reduce the amount of Pt in the cathode electrode, in which the sluggish ORR demands four to five times more Pt catalyst than in the anode. In this thesis is shown that the use of aligned carbon nanotubes (ACNTs) as Pt support, allows a more uniform distribution of the Pt nanoparticles, what in addition to their high hydrophobicity and high corrosive resistance, lead to improved mass transport and stability of the membrane electrode assembly (MEA), when compared to a benchmark MEA that uses Pt catalyst supported on carbon black. The improvement was accomplished using less Pt than in the benchmark MEA. Replacing Pt with non-PGM catalyst can lead to an

  7. A CFD analysis of transport phenomena and electrochemical reactions in a tubular-shaped PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Al-Najaf, P.O.Box 39 (Iraq)

    2013-07-01

    A fuel cell is most interesting new power source because it solves not only the environment problem but also natural resource exhaustion problem. CFD modeling and simulation for heat and mass transport in PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a tubular-shaped proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a tubular-shaped PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

  8. The Cell Nucleus in Physiological and Experimentally Induced Hypometabolism

    Science.gov (United States)

    Malatesta, M.

    The main problem for manned space mission is, at present, represented by the mass penalty associated to the human presence. An efficient approach could be the induction of a hypometabolic stasis in the astronauts, thus drastically reducing the physical and psychological requirements of the crew. On the other hand, in the wild, a reduction in resource consumptions physiologi- cally occurs in certain animals which periodically enter hibernation, a hypometabolic state in which both the energy need and energy offer are kept at a minimum. During the last twelve years, we have been studying different tissues of hibernating dormice, with the aim of analyzing their features during the euthermia -hibernation-arousal cycle as well as getting insight into the mechanisms allowing adaptation to hypometabolism. We paid particular attention to the cell nucleus, as it is the site of chief metabolic functions, such as DNA replication and RNA transcription. Our observations revealed no significant modification in the basic features of cell nuclei during hibernation; however, the cell nuclei of hibernating dormice showed unusual nuclear bodies containing molecules involved in RNA pathways. Therefore, we supposed that they could represent storage/assembly sites of several factors for processing some RNA which could be slowly synthesised during hibernation and rapidly and abundantly released in early arousal in order to meet the increased metabolic needs of the cell. The nucleolus also underwent structural and molecular modifications during hibernation, maybe to continue important nucleolar functions, or, alternatively, permit a most efficient reactivation upon arousal. On the basis of the observations made in vivo , we recently tried to experimentally induce a reversible hypometabolic state in in vitro models, using cell lines derived from hibernating and non-hibernating species. By administering the synthetic opioid DADLE, we could significantly reduce both RNA transcrip- tion and

  9. Transport Phenomena.

    Science.gov (United States)

    Shah, D. B.

    1984-01-01

    Describes a course designed to achieve a balance between exposing students to (1) advanced topics in transport phenomena, pointing out similarities and differences between three transfer processes and (2) common methods of solving differential equations. (JN)

  10. In situ diagnostic of two-phase flow phenomena in polymer electrolyte fuel cells by neutron imaging

    International Nuclear Information System (INIS)

    Kramer, Denis; Zhang, Jianbo; Shimoi, Ryoichi; Lehmann, Eberhard; Wokaun, Alexander; Shinohara, Kazuhiko; Scherer, Guenther G.

    2005-01-01

    Neutron radiographical measurements have been performed on operating hydrogen-fueled polymer electrolyte fuel cells (PEFC). With the successful detection of liquid accumulation in flow field and gas diffusion layer (GDL) under various operating conditions a unique experimental approach for the investigation of two-phase flow phenomena in technical PEFC has been realized. The experimental setup will be described in detail. Algorithms for an enhanced quantitative evaluation of the obtained images are presented and successful application to the data demonstrated. Finally, results from PEFC investigations will be given. Different flow field geometries and their implications for liquid accumulation inside flow field and GDL are discussed

  11. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2014-01-01

    Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport i...

  12. Heat science and transport phenomena in fuel cells; Thermique et phenomenes de transport dans les piles a combustible

    Energy Technology Data Exchange (ETDEWEB)

    Liberatore, P.M.; Boillot, M. [Laboratoire des Sciences du Genie Chimique de Nancy, 54 - Vandoeuvre-les-Nancy (France); Bonnet, C.; Didieerjean, S.; Lapicque, F.; Deseure, J.; Lottin, O.; Maillet, D.; Oseen-Senda, J. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 54 - Vandoeuvre Les Nancy (France); Alexandre, A. [Laboratoire d' Etudes Thermiques, ENSMA, 86 Poitiers (France); Topin, F.; Occelli, R.; Daurelle, J.V. [IUSTI / Polytech' Marseille, Institut universitaire des Systemes Thermiques Industriels Ecole, 13 - Marseille (France); Pauchet, J.; Feidt, M. [CEA Grenoble, Groupement pour la recherche sur les echangeurs thermiques (Greth), 38 (France); Voarino, C. [CEA Centre d' Etudes du Ripault, 37 - Tours (France); Morel, B.; Laurentin, J.; Bultel, Y.; Lefebvre-Joud, F. [CEA Grenoble, LEPMI, 38 (France); Auvity, B.; Lasbet, Y.; Castelain, C.; Peerohossaini, H. [Ecole Centrale de Nantes, Laboratoire de Thermocinetique de Nantes (LTN), 44 - Nantes (France)

    2005-07-01

    In this work are gathered the transparencies of the lectures presented at the conference 'heat science and transport phenomena in fuel cells'. The different lectures have dealt with 1)the gas distribution in the bipolar plates of a fuel cell: experimental studies and computerized simulations 2)two-phase heat distributors in the PEMFC 3)a numerical study of the flow properties of the backing layers on the transfers in a PEMFC 4)modelling of the heat and mass transfers in a PEMFC 5)two-phase cooling of the PEMFC with pentane 6)stationary thermodynamic model of the SOFC in the GECOPAC system 7)modelling of the internal reforming at the anode of the SOFC 8)towards a new thermal design of the PEMFC bipolar plates. (O.M.)

  13. Cell physiology regulation by hypoxia inducible factor-1: Targeting oxygen-related nanomachineries of hypoxic cells.

    Science.gov (United States)

    Eskandani, Morteza; Vandghanooni, Somayeh; Barar, Jaleh; Nazemiyeh, Hossein; Omidi, Yadollah

    2017-06-01

    Any dysfunctionality in maintaining the oxygen homeostasis by mammalian cells may elicit hypoxia/anoxia, which results in inescapable oxidative stress and possible subsequent detrimental impacts on certain cells/tissues with high demands to oxygen molecules. The ischemic damage in turn can trigger initiation of a number of diseases including organs ischemia, metabolic disorders, inflammatory diseases, different types of malignancies, and alteration in wound healing process. Thus, full comprehension of molecular mechanism(s) and cellular physiology of the oxygen homeostasis is the cornerstone of the mammalian cells metabolism, energetic pathways and health and disease conditions. An imbalance in oxygen content within the cellular microenvironment activates a cascade of molecular events that are often compensated, otherwise pathologic condition occurs through a complexed network of biomolecules. Hypoxia inducible factor-1 (HIF-1) plays a key transcriptional role in the adaptation of cell physiology in relation with the oxygen content within a cell. In this current study, we provide a comprehensive review on the molecular mechanisms of oxygen sensing and homeostasis and the impacts of HIF-1 in hypoxic/anoxic conditions. Moreover, different molecular and biochemical responses of the cells to the surrounding environment are discussed in details. Finally, modern technological approaches for targeting the hypoxia related proteins are articulated. Copyright © 2017. Published by Elsevier B.V.

  14. Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Abruna, Hector Daniel [Cornell University

    2013-08-01

    Our work is focused on membraneless laminar flow fuel cells, an unconventional fuel cell technology, intended to create a system that not only avoids most typical fuel cell drawbacks, but also achieves the highest power density yet recorded for a non-H{sub 2} fuel cell. We have employed rigorous electrochemistry to characterize the high-energy- density fuel BH4-, providing important mechanistic insight for anode catalyst choice and avoiding deleterious side reactions. Numerous fuel cell oxidants, used in place of O{sub 2}, are compared in a detailed, uniform manner, and a powerful new oxidant, cerium ammonium nitrate (CAN), is described. The high-voltage BH{sub 4}{sup -}/CAN fuel/oxidant combination is employed in a membraneless, room temperature, laminar-flow fuel cell, with herringbone micromixers which provide chaotic-convective flow which, in turn, enhances both the power output and efficiency of the device. We have also been involved in the design of a scaled-up version of the membraneless laminar flow fuel cell intended to provide a 10W output.

  15. Investigation of wave emission phenomena in dual frequency capacitive discharges using particle-in-cell simulation

    International Nuclear Information System (INIS)

    Sharma, S; Turner, M M

    2014-01-01

    Dual frequency capacitively coupled discharges are widely used during fabrication of modern-day integrated circuits, because of low cost and robust uniformity over broad areas. At low pressure, stochastic or collisionless electron heating is important in such discharges. The stochastic heating occurs adjacent to the sheath edge due to energy transfer from the oscillating high voltage electron sheath to electrons. The present research discusses evidence of wave emission from the sheath in such discharges, with a frequency near the electron plasma frequency. These waves are damped very promptly as they propagate away from the sheath towards the bulk plasma, by Landau damping or some related mechanism. In this work, the occurrence of strong wave phenomena during the expanding and collapsing phase of the low frequency sheath has been investigated. This is the result of a progressive breakdown of quasi-neutrality close to the electron sheath edge. The characteristics of waves in the dual-frequency case are entirely different from the single-frequency case studied in earlier works. The existence of a field reversal phenomenon, occurring several times within a lower frequency period in the proximity of the sheath is also reported. Electron trapping near to the field reversal regions also occurs many times during a lower frequency period. The emission of waves is associated with these field reversal regions. It is observed that the field reversal and electron trapping effects appear under conditions typical of many recent experiments, and are consequently of much greater practical interest than similar effects in single frequency discharges, which occur only under extreme conditions that are not usually realized in experiments. (paper)

  16. Computer Simulation Study of Collective Phenomena in Dense Suspensions of Red Blood Cells under Shear

    CERN Document Server

    Krüger, Timm

    2012-01-01

    The rheology of dense red blood cell suspensions is investigated via computer simulations based on the lattice Boltzmann, the immersed boundary, and the finite element methods. The red blood cells are treated as extended and deformable particles immersed in the ambient fluid. In the first part of the work, the numerical model and strategies for stress evaluation are discussed. In the second part, the behavior of the suspensions in simple shear flow is studied for different volume fractions, particle deformabilities, and shear rates. Shear thinning behavior is recovered. The existence of a shear-induced transition from a tumbling to a tank-treading motion is demonstrated. The transition can be parameterized by a single quantity, namely the effective capillary number. It is the ratio of the suspension stress and the characteristic particle membrane stress. At the transition point, a strong increase in the orientational order of the red blood cells and a significant decrease of the particle diffusivity are obser...

  17. Neutron Computed Tomography of Freeze/thaw Phenomena in Polymer Electrolyte Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Matthew M. Mech; Jack Brenizer; Kenan Unlu; A.K. Heller

    2008-12-12

    This report summarizes the final year's progress of the three-year NEER program. The overall objectives of this program were to 1) design and construct a sophisticated hight-resolution neutron computed tomography (NCT) facility, 2) develop novel and sophisticated liquid water and ice quantification analysis software for computed tomography, and 3) apply the advanced software and NCT capability to study liquid and ice distribution in polymer electrolyte fuel cells (PEFCs) under cold-start conditions. These objectives have been accomplished by the research team, enabling a new capability for advanced 3D image quantification with neutron imaging for fuel cell and other applications. The NCT water quantification methodology and software will greatly add to the capabilities of the neutron imaging community, and the quantified liquid water and ice distribution provided by its application to PEFCs will enhance understanding and guide design in the fuel cell community.

  18. Plasma generated in culture medium induces damages of HeLa cells due to flow phenomena

    Science.gov (United States)

    Sato, Yusuke; Sato, Takehiko; Yoshino, Daisuke

    2018-03-01

    Plasma in a liquid has been anticipated as an effective tool for medical applications, however, few reports have described cellular responses to plasma generated in a liquid similar to biological fluids. Herein we report the effects of plasma generated in a culture medium on HeLa cells. The plasma in the culture medium produced not only heat, shock waves, and reactive chemical species but also a jet flow with sub millimeter-sized bubbles. Cells exposed to the plasma exhibited detachment, morphological changes, and changes in the actin cytoskeletal structure. The experimental results suggest that wall shear stress over 160 Pa was generated on the surface of the cells by the plasma. It is one of the main factors that cause those cellular responses. We believe that our findings would provide valuable insight into advancements in medical applications of plasma in a liquid.

  19. Mathematical Modeling of Transport Phenomena in Polymer Electrolyte and Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Erik

    2004-02-01

    This thesis deals with modeling of two types of fuel cells: the polymer electrolyte fuel cell (PEFC) and the direct methanol fuel cell (DMFC), for which we address four major issues: a) mass transport limitations; b) water management (PEFC); c) gas management (DMFC); d) thermal management. Four models have been derived and studied for the PEFC, focusing on the cathode. The first exploits the slenderness of the cathode for a two-dimensional geometry, leading to a reduced model, where several non dimensional parameters capture the behavior of the cathode. The model was extended to three dimensions, where four different flow distributors were studied for the cathode. A quantitative comparison shows that the interdigitated channels can sustain the highest current densities. These two models, comprising isothermal gas phase flow, limit the studies to (a). Returning to a two-dimensional geometry of the PEFC, the liquid phase was introduced via a separate flow model approach for the cathode. In addition to conservation of mass, momentum and species, the model was extended to consider simultaneous charge and heat transfer for the whole cell. Different thermal, flow fields, and hydrodynamic conditions were studied, addressing (a), (b) and (d). A scale analysis allowed for predictions of the cell performance prior to any computations. Good agreement between experiments with a segmented cell and the model was obtained. A liquid-phase model, comprising conservation of mass, momentum and species, was derived and analyzed for the anode of the DMFC. The impact of hydrodynamic, electrochemical and geometrical features on the fuel cell performance were studied, mainly focusing on (a). The slenderness of the anode allows the use of a narrow-gap approximation, leading to a reduced model, with benefits such as reduced computational cost and understanding of the physical trends prior to any numerical computations. Adding the gas-phase via a multiphase mixture approach, the gas

  20. Non-dimensional analysis of PEM fuel cell phenomena by means of AC impedance measurements

    Science.gov (United States)

    Iranzo, Alfredo; Muñoz, Miguel; Pino, Fco. Javier; Rosa, Felipe

    AC impedance or electrochemical impedance spectroscopy (EIS) is becoming a fundamental technique used by researchers and scientists in proton exchange membrane (PEM) fuel cell analysis and development. In this work, in situ impedance measurements are presented for a series of operating conditions in a 50 cm 2 fuel cell. The electrode charge transfer resistance was determined from the corresponding arcs of the Nyquist diagrams. The analyses were performed for H 2/O 2 and H 2/air operation at different stoichiometric factors and reactant gases humidification. Characteristic time scales of charge transfer processes at the different operating conditions were estimated from the corresponding Bode plots. These values were used for a non-dimensional analysis of the different fuel cell electrochemical and transport processes, namely electrochemical reaction versus GDL reactant transport. Fuel cell adapted Damkhöler numbers are thus presented, where the results indicate that the GDL diffusion transport is the limiting process for the cases under analysis, especially when air is used as oxidant. Additional analysis of channel convective mass transport versus GDL diffusive mass transport is also presented.

  1. Lattice-Boltzmann simulation of multi-phase phenomena related to fuel cells

    Science.gov (United States)

    Akhgar, A.; Khalili, B.; Moa, B.; Rahnama, M.; Djilali, N.

    2017-07-01

    Fuel cells are devices that allow conversion of the chemical potential of a fuel and oxidant to produce electricity. A key component of a fuel cell is the catalyst layer, which facilitates the electrochemical reaction and where transport of reactants, charge, and byproduct heat and water take place. The structure and morphology of the catalyst layer determine its effectiveness and, in turn, strongly impact the overall performance and cost of a fuel cell. This paper discusses two central issue related to catalyst layers involving two-phase flow: liquid water transport in the catalyst layer during fuel cell operation, and fabrication of the catalyst layer from colloidal inks where a process of particle agglomeration takes place and eventually determines the final catalyst layer structure. Insight into these two issues are obtained using lattice-Botzmann based multi-phase simulations with formulations tailored to deal with features including high density ratio gas-liquid flow in complex porous media, and particle-particle and particle-hydrodynamic interactions.

  2. Nasal epithelial cells can act as a physiological surrogate for paediatric asthma studies.

    Directory of Open Access Journals (Sweden)

    Surendran Thavagnanam

    Full Text Available INTRODUCTION: Differentiated paediatric epithelial cells can be used to study the role of epithelial cells in asthma. Nasal epithelial cells are easier to obtain and may act as a surrogate for bronchial epithelium in asthma studies. We assessed the suitability of nasal epithelium from asthmatic children to be a surrogate for bronchial epithelium using air-liquid interface cultures. METHODS: Paired nasal and bronchial epithelial cells from asthmatic children (n = 9 were differentiated for 28 days under unstimulated and IL-13-stimulated conditions. Morphological and physiological markers were analysed using immunocytochemistry, transepithelial-electrical-resistance, Quantitative Real-time-PCR, ELISA and multiplex cytokine/chemokine analysis. RESULTS: Physiologically, nasal epithelial cells from asthmatic children exhibit similar cytokine responses to stimulation with IL-13 compared with paired bronchial epithelial cells. Morphologically however, nasal epithelial cells differed significantly from bronchial epithelial cells from asthmatic patients under unstimulated and IL-13-stimulated conditions. Nasal epithelial cells exhibited lower proliferation/differentiation rates and lower percentages of goblet and ciliated cells when unstimulated, while exhibiting a diminished and varied response to IL-13. CONCLUSIONS: We conclude that morphologically, nasal epithelial cells would not be a suitable surrogate due to a significantly lower rate of proliferation and differentiation of goblet and ciliated cells. Physiologically, nasal epithelial cells respond similarly to exogenous stimulation with IL-13 in cytokine production and could be used as a physiological surrogate in the event that bronchial epithelial cells are not available.

  3. Transport phenomena in solid oxide fuel cell electrodes focusing on heat transfer related to chemical reactions

    International Nuclear Information System (INIS)

    Navasa, M; Andersson, M; Yuan, J; Sundén, B

    2012-01-01

    Solid oxide fuel cells (SOFCs) are widely studied for their advantages especially at high temperatures. However, operating at high temperatures represents a high cost due to the strict requirements the materials are expected to fulfill. Thus, the main goal in SOFC research has been to decrease the operating temperature so that the range of available materials is widened and hence, the operating cost can be reduced. In this paper, the different heat sources that contribute to the cell energy balance are presented with strong emphasis on the chemical reactions that take place in SOFCs. The knowledge of which heat sources or sinks taking place and their locations within the SOFC can provide useful information for further design and efficiency improvements.

  4. Transport phenomena in the cathode of a molten carbonate fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Berg, P.; Findlay, J. [Univ. of Ontario Inst. of Technology, Oshawa, ON (Canada). Faculty of Science

    2009-07-01

    A molten carbonate fuel cell (MCFC) is an electrochemical energy conversion device that runs on natural gas and uses a molten salt electrolyte. In order to keep the electrolyte in this state, the cell must be kept at a temperature above 500 degrees C to eliminate the need for noble catalysts. This study focused on optimizing the electrode porosity to increase the power output of the fuel cell. The porosity was considered as a function of position, and was optimized using the MATLAB software package. The paper also described a newly developed model for the reaction-diffusion processes within the cathode of an MCFC. The model was developed using Fick Laws for diffusion and Darcy Laws were incorporated for convection. A model for binary diffusion was also discussed and compared to those for Fickian diffusion. There is a limiting case for diffusion across the cathode that depends on the conductivity for the liquid potential, for which there exists an analytical solution. Results were also discussed for varying diffusivities and permeabilities.

  5. Transport phenomena in the cathode of a molten carbonate fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Berg, P.; Findlay, J. [Faculty of Science, Univ. of Ontario Inst. of Technology, Oshawa, Ontario (Canada)

    2009-07-01

    'Full text': A Molten Carbonate Fuel Cell (MCFC) is an electro-chemical energy conversion technology that runs on natural gas and employs a molten salt electrolyte. In order to keep the electrolyte in this state, the cell must be kept at a temperature above 500 C, eliminating the need for noble catalysts. There has been only a limited amount of research on modelling the transport processes inside this device, mainly due to its limited ability for mobile applications. A model for the reaction-diffusion processes within the cathode of a MCFC is developed using Fick's Law for diffusion and incorporating Darcy's Law for convection. A model for Binary Diffusion is also discussed and compared to those for Fickian diffusion. It can be shown that there exists a limiting case for diffusion across the cathode that depends on the conductivity for the liquid potential, for which there exists an analytical solution. Results are also discussed for varying diffusivities and permeabilities. Ultimately, this research focuses on the optimization of the electrode porosity to increase the power output of the fuel cell. The porosity is considered as a function of position, and is optimized using the software package MATLAB. (author)

  6. Paradox phenomena of proton exchange membrane fuel cells operating under dead-end anode mode

    Science.gov (United States)

    Jiang, Dong; Zeng, Rong; Wang, Shumao; Jiang, Lijun; Varcoe, John R.

    2014-11-01

    By using two spatially separated reference electrodes in a single cell proton-exchange membrane fuel cell (PEMFC), the individual potentials of the anode and cathode are recorded under realistic operating conditions. The PEMFC is operated under dead-end anode (DEA) mode, without any humidification, to mitigate water accumulation at the anode. Although N2 crossover from cathode to anode may play an important role in PEMFCs operating under DEA mode, our results unexpectedly show that the over-potentials of both the anode and cathode concomitantly increased or decreased at the same time. The increases of over-potentials correlate to the increase of the high frequency resistance of the cell (Rhf) imply that the water content in the membrane electrode assemblies is critical. However, the subsequent H2 depletion tests suggest that water may accumulate at the interface between the surface of the catalyst and the ultrathin perfluorosulfonic acid (PFSA) ionomer film and this contradicts the above (the increase in Rhf implies the drying out of the MEAs). This study highlights the need for further research into understanding the water transport properties of the ultrathin PFSA ionomer film (<60 nm): it is clear that these exhibit completely different properties to that of bulk proton-exchange membranes (PEM).

  7. Cell survivor: Modeling radiobiological phenomena with a new kind of simulation

    Science.gov (United States)

    Spencer, Melissa A.

    Despite widespread societal fear of radiation, whether justified or unjustified, and whether related to medicine (e.g., CT scans) or other forms of nuclear and atomic radiation (e.g., nuclear power) there is a fundamental lack of basic understanding of radiation effects on the human body. Different types of radiation are psychologically grouped into the same general fear category irrespective of their different potential to do harm, and this fear is not balanced by their potential beneficial effects. By modeling certain types of radiation biology experiments within a game engine, it is possible to enhance the player's intuitive understanding of radiobiology, both the effects of different types of radiation as well as different environmental factors that can enhance or suppress repair. For this dissertation, a game/simulation has been developed that intends to narrow the gap between public perception and the reality of these physical processes. The building blocks of this simulation are cells, which are damaged by incident radiation, accumulating either single or double strand breaks. They grow and reproduce, and are especially vulnerable during certain phases of the cell cycle (e.g. mitosis). Two dominant damage mechanisms are modeled, along with multiple repair mechanisms, for example, double strand breaks can be repaired by either non-homologous end joining or homologous repair. The output of the developed simulation was compared to data collected in experimental studies and the simulation appears to be a valid representation of the dominant mechanisms of radiobiology, as far as can be determined within the scope of this dissertation. Cell survival curves generated from playtest data display shoulders that depend on the LET of incident radiation, and rest time restores repair capability. In addition to public outreach, the presented code can be used to aid investigators by collecting data during play that can be used as a distributed Monte Carlo simulation

  8. Modelling the effect of inhomogeneous compression of GDL on local transport phenomena in a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Karvonen, S.; Mikkola, M. [Laboratory of Advanced Energy Systems, Helsinki University of Technology (Finland); Himanen, O. [VTT Technical Research Center of Finland, Fuel Cells, VTT (Finland); Nitta, I.

    2008-12-15

    The effects of inhomogeneous compression of gas diffusion layers (GDLs) on local transport phenomena within a polymer electrolyte membrane (PEM) fuel cell were studied theoretically. The inhomogeneous compression induced by the rib/channel structure of the flow field plate causes partial deformation of the GDLs and significantly affects component parameters. The results suggest that inhomogeneous compression does not significantly affect the polarisation behaviour or gas-phase mass transport. However, the effect of inhomogeneous compression on the current density distribution is evident. Local current density under the channel was substantially smaller than that under the rib when inhomogeneous compression was taken into account, while the current density distribution was fairly uniform for the model which excluded the effect of inhomogeneous compression. This is caused by the changes in the selective current path, which is determined by the combination of conductivities of components and contact resistance between them. Despite the highly uneven current distribution and variation in material parametres as a function of GDL thickness, the temperature profile was relatively even over the active area for both the modelled cases, contrary to predictions in previous studies. However, an abnormally high current density significantly accelerates deterioration of the membrane and is critical in terms of cell durability. Therefore, fuel cells should be carefully designed to minimise the harmful effects of inhomogeneous compression. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  9. Modeling of the Transport Phenomena in Passive Direct Methanol Fuel Cells Using a Two-Phase Anisotropic Model

    Directory of Open Access Journals (Sweden)

    Zheng Miao

    2014-04-01

    Full Text Available The transport phenomena in a passive direct methanol fuel cell (DMFC were numerically simulated by the proposed two-dimensional two-phase nonisothermal mass transport model. The anisotropic transport characteristic and deformation of the gas diffusion layer (GDL were considered in this model. The natural convection boundary conditions were adopted for the transport of methanol, oxygen, and heat at the GDL outer surface. The effect of methanol concentration in the reservoir on cell performance was examined. The distribution of multiphysical fields in the membrane electrode assembly (MEA, especially in the catalyst layers (CLs, was obtained and analyzed. The results indicated that transport resistance for the methanol mainly existed in the MEA while that for oxygen and heat was primarily due to natural convection at the GDL outer surface. Because of the relatively high methanol concentration, the local reaction rate in CLs was mainly determined by the overpotential. Methanol concentration between 3 M and 4 M was recommended for passive liquid feed DMFC in order to achieve a balance between the cell performance and the methanol crossover.

  10. Transport phenomena in polymer electrolyte membrane fuel cells via voltage loss breakdown

    Science.gov (United States)

    Flick, Sarah; Dhanushkodi, Shankar R.; Mérida, Walter

    2015-04-01

    This study presents a voltage loss breakdown method based on in-situ experimental data to systematically analyze the different overpotentials of a polymer electrolyte membrane fuel cell. This study includes a systematic breakdown of the anodic overpotentials via the use of a reference electrode system. This work demonstrates the de-convolution of the individual overpotentials for both anode and cathode side, including the distinction between mass-transport overpotentials in cathode porous transport layer (PTL) and electrode, based on in-situ polarization tests under different operating conditions. This method is used to study the relationship between mass-transport losses inside the cathode catalyst layer (CL) and the PTL for both a single layer and two-layer PTL configuration. We conclude that the micro-porous layer (MPL) significantly improves the water removal within the cell, especially inside the cathode electrode, and therefore the mass transport within the cathode CL. This study supports the theory that the MPL on the cathode leads to an increase in water permeation from cathode to anode due to its function as a capillary barrier. This is reflected in increased anodic mass-transport overpotential, decreased ohmic losses and decreased cathode mass-transport losses, especially in the cathode electrode.

  11. Amnion-Epithelial-Cell-Derived Exosomes Demonstrate Physiologic State of Cell under Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Samantha Sheller

    Full Text Available At term, the signals of fetal maturity and feto-placental tissue aging prompt uterine readiness for delivery by transitioning quiescent myometrium to an active stage. It is still unclear how the signals reach the distant myometrium. Exosomes are a specific type of extracellular vesicle (EVs that transport molecular signals between cells, and are released from a wide range of cells, including the maternal and fetal cells. In this study, we hypothesize that i exosomes act as carriers of signals in utero-placental compartments and ii exosomes reflect the physiologic status of the origin cells. The primary aims of this study were to determine exosomal contents in exosomes derived from primary amnion epithelial cells (AEC. We also determined the effect of oxidative stress on AEC derived exosomal cargo contents. AEC were isolated from amniotic membrane obtained from normal, term, not in labor placentae at delivery, and culture under standard conditions. Oxidative stress was induced using cigarette smoke extract for 48 hours. AEC-conditioned media were collected and exosomes isolated by differential centrifugations. Both growth conditions (normal and oxidative stress induced produced cup shaped exosomes of around 50 nm, expressed exosomes enriched markers, such as CD9, CD63, CD81 and HSC70, embryonic stem cell marker Nanog, and contained similar amounts of cell free AEC DNA. Using confocal microscopy, the colocalization of histone (H 3, heat shock protein (HSP 70 and activated form of pro-senescence and term parturition associated marker p38 mitogen activated protein kinase (MAPK (P-p38 MAPK co-localized with exosome enrich marker CD9. HSP70 and P-p38 MAPK were significantly higher in exosomes from AEC grown under oxidative stress conditions than standard conditions (p<0.05. Finally, mass spectrometry and bioinformatics analysis identified 221 different proteins involved in immunomodulatory response and cell-to-cell communication. This study determined

  12. Modeling the phenomena of dehydration and flooding of a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Gerteisen, Dietmar; Heilmann, Timothy; Ziegler, Christoph

    A one-dimensional, two-phase, transient PEM fuel cell model including gas diffusion layer, cathode catalyst layer and membrane is developed. The electrode is assumed to consist of a network of dispersed Pt/C forming spherically shaped agglomerated zones that are filled with electrolyte. Water is modeled in all three phases: vapor, liquid and dissolved in the ionomer to capture the effect of dehydration of the ionomer as well as flooding of the porous media. The anode is modeled as a sophisticated spatially reduced interface. Motivated by environmental scanning electron microscope (ESEM) images of contact angles for microscopic water droplets on fibers of the gas diffusion layer, we introduce the feature of immobile saturation. A step change of the saturation between the catalyst layer and the gas diffusion layer is modeled based on the assumption of a continuous capillary pressure at the interface. The model is validated against voltammetry experiments under various humidification conditions which all show hysteresis effects in the mass transport limited region. The transient saturation profiles clearly show that insufficient liquid water removal causes pore flooding, which is responsible for the oxygen mass transport limitation at high current density values. The simulated and measured current responses from chronoamperometry experiments are compared and analyzed.

  13. Restoring physiological cell heterogeneity in the mesenchyme during tooth engineering.

    Science.gov (United States)

    Keller, Laetitia-Véronique; Kuchler-Bopp, Sabine; Lesot, Hervé

    2012-01-01

    Tooth development is controlled by reciprocal epithelial-mesenchymal interactions. Complete teeth can form when culturing and implanting re-associations between single embryonic dental epithelial and mesenchymal cells. Although epithelial histogenesis is clear, very little is known about cell diversity and patterning in the mesenchyme. The aim of this work was to compare the situation in engineered and developing teeth at similar developmental stages. To this end, the expression of cell surface markers in the mesenchyme was investigated by immunostaining in: 1) embryonic mouse molars at embryonic day 14, as the initial cell source for re-associations, 2) cultured cell re-associations just before their implantation and 3) cultured cell re-associations implanted for two weeks. Surface markers allowed visualization of the complex patterning of different cell types and the differential timing in their appearance. The phenotype of mesenchymal cells rapidly changed when they were grown as a monolayer, even without passage. This might explain the rapid loss of their potential to sustain tooth formation after re-association. Except for markers associated with vascularization, which is not maintained in vitro, the staining pattern in the mesenchyme of cultured re-associations was similar to that observed in situ. After implantation, vascularization and the cellular heterogeneity in the mesenchyme were similar to what was observed in developing molars. Besides tissue oxygenation and its role in mineralization of dental matrices, vascularization is involved in the progressive increase in mesenchymal cell heterogeneity, by allowing external cells to enter the mesenchyme.

  14. Modeling the effect of anisotropy of gas diffusion layer on transport phenomena in a direct methanol fuel cell

    Science.gov (United States)

    Miao, Zheng; He, Ya-Ling; Zou, Jin-Qiang

    Transport phenomena in the gas diffusion layer (GDL) are of vital importance for the operation of direct methanol fuel cells (DMFCs). In this work, a two-phase mass transport model is developed to investigate the effects of anisotropic characteristics of a GDL, including the inherent anisotropy, deformation, and electrical and thermal contact resistances, on the coupled species, charges and thermal transport processes in a DMFC. In this model, methanol crossover and non-equilibrium evaporation/condensation of water and methanol are considered. The multistep electrochemical mechanisms are used to obtain a detailed description of the kinetics of methanol oxidization reaction (MOR) in both the anode and cathode catalyst layers (CLs). The numerical results show that the anisotropy of the GDL has a great effect on the distribution of species concentration, overpotential, local current density, and temperature. The deformation of the GDL depresses the transport of species through the GDL, particularly methanol diffusion in anode GDL, but facilitates the transport of electron and the removal of heat. The electrical contact resistance plays an important role in determining the cell performance.

  15. Modeling the effect of anisotropy of gas diffusion layer on transport phenomena in a direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Zheng; He, Ya-Ling; Zou, Jin-Qiang [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)

    2010-06-01

    Transport phenomena in the gas diffusion layer (GDL) are of vital importance for the operation of direct methanol fuel cells (DMFCs). In this work, a two-phase mass transport model is developed to investigate the effects of anisotropic characteristics of a GDL, including the inherent anisotropy, deformation, and electrical and thermal contact resistances, on the coupled species, charges and thermal transport processes in a DMFC. In this model, methanol crossover and non-equilibrium evaporation/condensation of water and methanol are considered. The multistep electrochemical mechanisms are used to obtain a detailed description of the kinetics of methanol oxidization reaction (MOR) in both the anode and cathode catalyst layers (CLs). The numerical results show that the anisotropy of the GDL has a great effect on the distribution of species concentration, overpotential, local current density, and temperature. The deformation of the GDL depresses the transport of species through the GDL, particularly methanol diffusion in anode GDL, but facilitates the transport of electron and the removal of heat. The electrical contact resistance plays an important role in determining the cell performance. (author)

  16. Physiology and Regulation of Calcium Channels in Stomatal Guard Cells

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Julian I.

    2007-05-02

    Stomatal pores in the epidermis of leaves regulate the diffusion of CO2 into leaves for photosynthetic carbon fixation and control water loss of plants during drought periods. Guard cells sense CO2, water status, light and other environmental conditions to regulate stomatal apertures for optimization of CO2 intake and plant growth under drought stress. The cytosolic second messenger calcium contributes to stomatal movements by transducing signals and regulating ion channels in guard cells. Studies suggest that both plasma membrane Ca2+ influx channels and vacuolar/organellar Ca2+ release channels contribute to ABA-induced Ca2+ elevations in guard cells. Recent research in the P.I.'s laboratory has led to identification of a novel major cation-selective Ca2+-permeable influx channel (Ica) in the plasma membrane of Arabidopsis guard cells. These advances will allow detailed characterization of Ica plasma membrane Ca2+ influx channels in guard cells. The long term goal of this research project is to gain a first detailed characterization of these novel plasma membrane Ca2+-permeable channel currents in Arabidopsis guard cells. The proposed research will investigate the hypothesis that Ica represents an important Ca2+ influx pathway for ABA and CO2 signal transduction in Arabidopsis guard cells. These studies will lead to elucidation of key signal transduction mechanisms by which plants balance CO2 influx into leaves and transpirational water loss and may contribute to future strategies for manipulating gas exchange for improved growth of crop plants and for biomass production.

  17. Numerical study of cell performance and local transport phenomena in PEM fuel cells with various flow channel area ratios

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Dong [Department of Thermal Engineering, School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Duan, Yuan-Yuan [Key Laboratory of Thermal Science and Power Engineering of MOE, Tsinghua University, Beijing 100084 (China); Yan, Wei-Mon [Department of Mechatronic Engineering, Huafan University, Shih-Ting 22305 (China)

    2007-10-11

    Three-dimensional models of proton exchange membrane fuel cells (PEMFCs) with parallel and interdigitated flow channel designs were developed including the effects of liquid water formation on the reactant gas transport. The models were used to investigate the effects of the flow channel area ratio and the cathode flow rate on the cell performance and local transport characteristics. The results reveal that at high operating voltages, the cell performance is independent of the flow channel designs and operating parameters, while at low operating voltages, both significantly affect cell performance. For the parallel flow channel design, as the flow channel area ratio increases the cell performance improves because fuel is transported into the diffusion layer and the catalyst layer mainly by diffusion. A larger flow channel area ratio increases the contact area between the fuel and the diffusion layer, which allows more fuel to directly diffuse into the porous layers to participate in the electrochemical reaction which enhances the reaction rates. For the interdigitated flow channel design, the baffle forces more fuel to enter the cell and participate in the electrochemical reaction, so the flow channel area ratio has less effect. Forced convection not only increases the fuel transport rates but also enhances the liquid water removal, thus interdigitated flow channel design has higher performance than the parallel flow channel design. The optimal performance for the interdigitated flow channel design occurs for a flow channel area ratio of 0.4. The cell performance also improves as the cathode flow rate increases. The effects of the flow channel area ratio and the cathode flow rate on cell performance are analyzed based on the local current densities, oxygen flow rates and liquid water concentrations inside the cell. (author)

  18. Three-dimensional multi-phase flow computational fluid dynamics model for analysis of transport phenomena and thermal stresses in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Maher, A.R.; Al-Baghdadi, S. [International Technological Univ., London (United Kingdom). Dept. of Mechanical Engineering; Haroun, A.K.; Al-Janabi, S. [Babylon Univ., Babylon (Iraq). Dept. of Mechanical Engineering

    2007-07-01

    Fuel cell technology is expected to play an important role in meeting the growing demand for distributed generation because it can convert the chemical energy of a clean fuel directly into electrical energy. An operating fuel cell has varying local conditions of temperature, humidity, and power generation across the active area of the fuel cell in 3D. This paper presented a model that was developed to improve the basic understanding of the transport phenomena and thermal stresses in PEM fuel cells, and to investigate the behaviour of polymer membrane under hygro and thermal stresses during the cell operation. This comprehensive 3D, multiphase, non-isothermal model accounts for the major transport phenomena in a PEM fuel cell, notably convective and diffusive heat and mass transfer; electrode kinetics; transport and phase change mechanism of water; and potential fields. The model accounts for the liquid water flux inside the gas diffusion layers by viscous and capillary forces and can therefore predict the amount of liquid water inside the gas diffusion layers. This study also investigated the key parameters affecting fuel cell performance including geometry, materials and operating conditions. The model considers the many interacting, complex electrochemical, transport phenomena, thermal stresses and deformation that cannot be studied experimentally. It was concluded that the model can provide a computer-aided tool for the design and optimization of future fuel cells with much higher power density and lower cost. 21 refs., 2 tabs., 14 figs.

  19. Ca2+ signaling in pancreatic acinar cells: physiology and pathophysiology

    Directory of Open Access Journals (Sweden)

    O.H. Petersen

    2009-01-01

    Full Text Available The pancreatic acinar cell is a classical model for studies of secretion and signal transduction mechanisms. Because of the extensive endoplasmic reticulum and the large granular compartment, it has been possible - by direct measurements - to obtain considerable insights into intracellular Ca2+ handling under both normal and pathological conditions. Recent studies have also revealed important characteristics of stimulus-secretion coupling mechanisms in isolated human pancreatic acinar cells. The acinar cells are potentially dangerous because of the high intra-granular concentration of proteases, which become inappropriately activated in the human disease acute pancreatitis. This disease is due to toxic Ca2+ signals generated by excessive liberation of Ca2+ from both the endoplasmic reticulum and the secretory granules.

  20. Efficient particle-in-cell simulation of auroral plasma phenomena using a CUDA enabled graphics processing unit

    Science.gov (United States)

    Sewell, Stephen

    This thesis introduces a software framework that effectively utilizes low-cost commercially available Graphic Processing Units (GPUs) to simulate complex scientific plasma phenomena that are modeled using the Particle-In-Cell (PIC) paradigm. The software framework that was developed conforms to the Compute Unified Device Architecture (CUDA), a standard for general purpose graphic processing that was introduced by NVIDIA Corporation. This framework has been verified for correctness and applied to advance the state of understanding of the electromagnetic aspects of the development of the Aurora Borealis and Aurora Australis. For each phase of the PIC methodology, this research has identified one or more methods to exploit the problem's natural parallelism and effectively map it for execution on the graphic processing unit and its host processor. The sources of overhead that can reduce the effectiveness of parallelization for each of these methods have also been identified. One of the novel aspects of this research was the utilization of particle sorting during the grid interpolation phase. The final representation resulted in simulations that executed about 38 times faster than simulations that were run on a single-core general-purpose processing system. The scalability of this framework to larger problem sizes and future generation systems has also been investigated.

  1. Microstructural analysis of mass transport phenomena in gas diffusion media for high current density operation in PEM fuel cells

    Science.gov (United States)

    Kotaka, Toshikazu; Tabuchi, Yuichiro; Mukherjee, Partha P.

    2015-04-01

    Cost reduction is a key issue for commercialization of fuel cell electric vehicles (FCEV). High current density operation is a solution pathway. In order to realize high current density operation, it is necessary to reduce mass transport resistance in the gas diffusion media commonly consisted of gas diffusion layer (GDL) and micro porous layer (MPL). However, fundamental understanding of the underlying mass transport phenomena in the porous components is not only critical but also not fully understood yet due to the inherent microstructural complexity. In this study, a comprehensive analysis of electron and oxygen transport in the GDL and MPL is conducted experimentally and numerically with three-dimensional (3D) microstructural data to reveal the structure-transport relationship. The results reveal that the mass transport in the GDL is strongly dependent on the local microstructural variations, such as local pore/solid volume fractions and connectivity. However, especially in the case of the electrical conductivity of MPL, the contact resistance between carbon particles is the dominant factor. This suggests that reducing the contact resistance between carbon particles and/or the number of contact points along the transport pathway can improve the electrical conductivity of MPL.

  2. Plant Physiology: FERONIA Defends the Cell Walls against Corrosion.

    Science.gov (United States)

    Verger, Stéphane; Hamant, Olivier

    2018-03-05

    A new study uncovers the role of wall sensing and remodeling in the plant response to salt stress, identifying the FERONIA receptor kinase as a key player in that process, likely through direct sensing of cell wall pectins. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Bone marrow-derived cells are differentially involved in pathological and physiological retinal angiogenesis in mice

    International Nuclear Information System (INIS)

    Zou, He; Otani, Atsushi; Oishi, Akio; Yodoi, Yuko; Kameda, Takanori; Kojima, Hiroshi; Yoshimura, Nagahisa

    2010-01-01

    Purpose: Bone marrow-derived cells have been shown to play roles in angiogenesis. Although these cells have been shown to promote angiogenesis, it is not yet clear whether these cells affect all types of angiogenesis. This study investigated the involvement of bone marrow-derived cells in pathological and physiological angiogenesis in the murine retina. Materials and methods: The oxygen-induced retinopathy (OIR) model was used as a retinal angiogenesis model in newborn mice. To block the influence of bone marrow-derived cells, the mice were irradiated with a 4-Gy dose of radiation from a 137 Cs source. Irradiation was performed in four different conditions with radio dense 2-cm thick lead disks; (1) H group, the head were covered with these discs to protect the eyes from radiation; (2) A group, all of the body was covered with these discs; (3) N group, mice were completely unshielded; (4) C group, mice were put in the irradiator but were not irradiated. On P17, the retinal areas showing pathological and physiological retinal angiogenesis were measured and compared to the retinas of nonirradiated mice. Results: Although irradiation induced leukocyte depletion, it did not affect the number of other cell types or body weight. Retinal nonperfusion areas were significantly larger in irradiated mice than in control mice (P < 0.05), indicating that physiological angiogenesis was impaired. However, the formation of tuft-like angiogenesis processes was more prominent in the irradiated mice (P < 0.05), indicating that pathological angiogenesis was intact. Conclusions: Bone marrow-derived cells seem to be differentially involved in the formation of physiological and pathological retinal vessels. Pathological angiogenesis in the murine retina does not require functional bone marrow-derived cells, but these cells are important for the formation of physiological vessels. Our results add a new insight into the pathology of retinal angiogenesis and bolster the hypothesis that bone

  4. Modeling Physiological Events in 2D vs. 3D Cell Culture.

    Science.gov (United States)

    Duval, Kayla; Grover, Hannah; Han, Li-Hsin; Mou, Yongchao; Pegoraro, Adrian F; Fredberg, Jeffery; Chen, Zi

    2017-07-01

    Cell culture has become an indispensable tool to help uncover fundamental biophysical and biomolecular mechanisms by which cells assemble into tissues and organs, how these tissues function, and how that function becomes disrupted in disease. Cell culture is now widely used in biomedical research, tissue engineering, regenerative medicine, and industrial practices. Although flat, two-dimensional (2D) cell culture has predominated, recent research has shifted toward culture using three-dimensional (3D) structures, and more realistic biochemical and biomechanical microenvironments. Nevertheless, in 3D cell culture, many challenges remain, including the tissue-tissue interface, the mechanical microenvironment, and the spatiotemporal distributions of oxygen, nutrients, and metabolic wastes. Here, we review 2D and 3D cell culture methods, discuss advantages and limitations of these techniques in modeling physiologically and pathologically relevant processes, and suggest directions for future research. Copyright © 2017 the American Physiological Society.

  5. DNA methylation in states of cell physiology and pathology.

    Directory of Open Access Journals (Sweden)

    Lech Chyczewski

    2007-10-01

    Full Text Available DNA methylation is one of epigenetic mechanisms regulating gene expression. The methylation pattern is determined during embryogenesis and passed over to differentiating cells and tissues. In a normal cell, a significant degree of methylation is characteristic for extragenic DNA (cytosine within the CG dinucleotide while CpG islands located in gene promoters are unmethylated, except for inactive genes of the X chromosome and the genes subjected to genomic imprinting. The changes in the methylation pattern, which may appear as the organism age and in early stages of cancerogenesis, may lead to the silencing of over ninety endogenic genes. It has been found, that these disorders consist not only of the methylation of CpG islands, which are normally unmethylated, but also of the methylation of other dinucleotides, e.g. CpA. Such methylation has been observed in non-small cell lung cancer, in three regions of the exon 5 of the p53 gene (so-called "non-CpG" methylation. The knowledge of a normal methylation process and its aberrations appeared to be useful while searching for new markers enabling an early detection of cancer. With the application of the Real-Time PCR technique (using primers for methylated and unmethylated sequences five new genes which are potential biomarkers of lung cancer have been presented.

  6. Changes in ganglion cell physiology during retinal degeneration influence excitability by prosthetic electrodes

    Science.gov (United States)

    Cho, Alice; Ratliff, Charles; Sampath, Alapakkam; Weiland, James

    2016-04-01

    Objective. Here we investigate ganglion cell physiology in healthy and degenerating retina to test its influence on threshold to electrical stimulation. Approach. Age-related Macular Degeneration and Retinitis Pigmentosa cause blindness via outer retinal degeneration. Inner retinal pathways that transmit visual information to the central brain remain intact, so direct electrical stimulation from prosthetic devices offers the possibility for visual restoration. Since inner retinal physiology changes during degeneration, we characterize physiological properties and responses to electrical stimulation in retinal ganglion cells (RGCs) of both wild type mice and the rd10 mouse model of retinal degeneration. Main results. Our aggregate results support previous observations that elevated thresholds characterize diseased retinas. However, a physiology-driven classification scheme reveals distinct sub-populations of ganglion cells with thresholds either normal or strongly elevated compared to wild-type. When these populations are combined, only a weakly elevated threshold with large variance is observed. The cells with normal threshold are more depolarized at rest and exhibit periodic oscillations. Significance. During degeneration, physiological changes in RGCs affect the threshold stimulation currents required to evoke action potentials.

  7. Cell death patterns in Arabidopsis cells subjected to four physiological stressors indicate multiple signalling pathways and cell cycle phase specificity.

    Science.gov (United States)

    Pathirana, Ranjith; West, Phillip; Hedderley, Duncan; Eason, Jocelyn

    2017-03-01

    Corpse morphology, nuclear DNA fragmentation, expression of senescence-associated genes (SAG) and cysteine protease profiles were investigated to understand cell death patterns in a cell cycle-synchronised Arabidopsis thaliana cell suspension culture treated with four physiological stressors in the late G2 phase. Within 4 h of treatment, polyethylene glycol (PEG, 20 %), mannose (100 mM) and hydrogen peroxide (2 mM) caused DNA fragmentation coinciding with cell permeability to Evans Blue (EB) and produced corpse morphology corresponding to apoptosis-like programmed cell death (AL-PCD) with cytoplasmic retraction from the cell wall. Ethylene (8 mL per 250-mL flask) caused permeability of cells to EB without concomitant nuclear DNA fragmentation and cytoplasmic retraction, suggesting necrotic cell death. Mannose inducing glycolysis block and PEG causing dehydration resulted in relatively similar patterns of upregulation of SAG suggesting similar cell death signalling pathways for these two stress factors, whereas hydrogen peroxide caused unique patterns indicating an alternate pathway for cell death induced by oxidative stress. Ethylene did not cause appreciable changes in SAG expression, confirming necrotic cell death. Expression of AtDAD, BoMT1 and AtSAG2 genes, previously shown to be associated with plant senescence, also changed rapidly during AL-PCD in cultured cells. The profiles of nine distinct cysteine protease-active bands ranging in size from ca. 21.5 to 38.5 kDa found in the control cultures were also altered after treatment with the four stressors, with mannose and PEG again producing similar patterns. Results also suggest that cysteine proteases may have a role in necrotic cell death.

  8. The Importance of Physiologically Relevant Cell Lines for Studying Virus–Host Interactions

    Directory of Open Access Journals (Sweden)

    David Hare

    2016-11-01

    Full Text Available Viruses interact intimately with the host cell at nearly every stage of replication, and the cell model that is chosen to study virus infection is critically important. Although primary cells reflect the phenotype of healthy cells in vivo better than cell lines, their limited lifespan makes experimental manipulation challenging. However, many tumor-derived and artificially immortalized cell lines have defects in induction of interferon-stimulated genes and other antiviral defenses. These defects can affect virus replication, especially when cells are infected at lower, more physiologically relevant, multiplicities of infection. Understanding the selective pressures and mechanisms underlying the loss of innate signaling pathways is helpful to choose immortalized cell lines without impaired antiviral defense. We describe the trials and tribulations we encountered while searching for an immortalized cell line with intact innate signaling, and how directed immortalization of primary cells avoids many of the pitfalls of spontaneous immortalization.

  9. Geometrical Effects on Nonlinear Electrodiffusion in Cell Physiology

    Science.gov (United States)

    Cartailler, J.; Schuss, Z.; Holcman, D.

    2017-12-01

    We report here new electrical laws, derived from nonlinear electrodiffusion theory, about the effect of the local geometrical structure, such as curvature, on the electrical properties of a cell. We adopt the Poisson-Nernst-Planck equations for charge concentration and electric potential as a model of electrodiffusion. In the case at hand, the entire boundary is impermeable to ions and the electric field satisfies the compatibility condition of Poisson's equation. We construct an asymptotic approximation for certain singular limits to the steady-state solution in a ball with an attached cusp-shaped funnel on its surface. As the number of charge increases, they concentrate at the end of cusp-shaped funnel. These results can be used in the design of nanopipettes and help to understand the local voltage changes inside dendrites and axons with heterogeneous local geometry.

  10. Physiological characterization of secondary metabolite producing Penicillium cell factories

    DEFF Research Database (Denmark)

    Grijseels, Sietske; Nielsen, Jens; Nielsen, Jens

    2017-01-01

    Penicillium species are important producers of bioactive secondary metabolites. However, the immense diversity of the fungal kingdom is only scarcely represented in industrial bioprocesses and the upscaling of compound production remains a costly and labor intensive challenge. In order to facilit......Penicillium species are important producers of bioactive secondary metabolites. However, the immense diversity of the fungal kingdom is only scarcely represented in industrial bioprocesses and the upscaling of compound production remains a costly and labor intensive challenge. In order...... to facilitate the development of novel secondary metabolite producing processes, two routes are typically explored: optimization of the native producer or transferring the enzymatic pathway into a heterologous host. Recent genome sequencing of ten Penicillium species showed the vast amount of secondary...... metabolite gene clusters present in their genomes, and makes them accessible for rational strain improvement. In this study, we aimed to characterize the potential of these ten Penicillium species as native producing cell factories by testing their growth performance and secondary metabolite production...

  11. The influence of physical and physiological cues on atomic force microscopy-based cell stiffness assessment.

    Directory of Open Access Journals (Sweden)

    Yu-Wei Chiou

    Full Text Available Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young's modulus (E(eff relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues.

  12. Effects of physiological levels of the green tea extract Epigallocatechin gallate (EGCG on breast cancer cells

    Directory of Open Access Journals (Sweden)

    Li eZeng

    2014-05-01

    Full Text Available Physiological concentrations of the green tea extract EGCG caused growth inhibition in oestrogen receptor α (ERα-positive MCF7 cells, that was associated with down-regulation of the ERα and reduced insulin-like growth factor (IGF binding protein-2 (IGFBP-2 abundance and increased protein abundance of the tumour suppressor genes p53/p21. In contrast to MCF7 cells that have wt p53, EGCG alone did not change cell proliferation or death significantly in another ERα-positive cell line T47D that possesses mutant p53. EGCG increased ERα protein levels and as a consequence, the cells responded significantly better to an ERα antagonist Tamoxifen (TAM in the presence of EGCG. EGCG significantly increased cell death in an ERα-negative cell line, MDA-MB-231 that also possesses mutant p53. EGCG significantly increased the ERα and IGF-I receptor (IGF-IR levels and thereby enhanced the sensitivities of the cells to Tamoxifen and a blocking antibody targeting the IGF-1R (αIR3. In contrast to MCF7, T47D and MDA-MB-231 breast cancer cells that exhibited significant changes in key molecules involved in breast growth and survival upon treatment with physiological levels of EGCG, the growth, survival and levels of these proteins in non-malignant breast epithelial cells, MCF10A cells, were not affected.

  13. [Effects of hydrostatic pressure in physiological range on bladder smooth muscle cells in vitro].

    Science.gov (United States)

    Wei, Tangqiang; Chen, Lin; Wang, Yan; Xu, Feng; Wang, Kanjie

    2012-08-01

    To explore the effects of the physiological range of hydrostatic pressure on human bladder smooth muscle cells (HBSMCs) cultured in vitro, we used a hydrostatic compression device designed in our laboratory into the experiments, which were grouped by varied hydrostatic pressure gradients. Cellular morphology was observed with HE staining; cytoskeleton F-actin, cell cycle, both proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase 7 (MMP-7) were detected respectively with immunofluorescence, flow cytometry and RT-PCR. We found that the proliferation, cytoskeleton and cycle distribution of HBSMCs were not obviously different among the groups of different hydrostatic pressure; however, the mRNA expression of MMP-7 exhibited a trend of first increasing and then declining as the pressure gradually rises. Thus the physiological range of hydrostatic pressure may not have significant influence on proliferation, morphology, skeleton, and cell cycle of HBSMCs, but it may have great effect on the expression of MMP-7.

  14. From good to bad : Intravital imaging of the hijack of physiological processes by cancer cells

    NARCIS (Netherlands)

    Suijkerbuijk, Saskia J.E.; van Rheenen, Jacco

    2017-01-01

    Homeostasis of tissues is tightly regulated at the cellular, tissue and organismal level. Interestingly, tumor cells have found ways to hijack many of these physiological processes at all the different levels. Here we review how intravital microscopy techniques have provided new insights into our

  15. Cell physiology of plants growing in cold environments.

    Science.gov (United States)

    Lütz, Cornelius

    2010-08-01

    The life of plants growing in cold extreme environments has been well investigated in terms of morphological, anatomical, and ecophysiological adaptations. In contrast, long-term cellular or metabolic studies have been performed by only a few groups. Moreover, a number of single reports exist, which often represent just a glimpse of plant behavior. The review draws together the literature which has focused on tissue and cellular adaptations mainly to low temperatures and high light. Most studies have been done with European alpine plants; comparably well studied are only two phanerogams found in the coastal Antarctic. Plant adaptation in northern polar regions has always been of interest in terms of ecophysiology and plant propagation, but nowadays, this interest extends to the effects of global warming. More recently, metabolic and cellular investigations have included cold and UV resistance mechanisms. Low-temperature stress resistance in plants from cold environments reflects the climate conditions at the growth sites. It is now a matter of molecular analyses to find the induced genes and their products such as chaperones or dehydrins responsible for this resistance. Development of plants under snow or pollen tube growth at 0 degrees C shows that cell biology is needed to explain the stability and function of the cytoskeleton. Many results in this field are based on laboratory studies, but several publications show that it is not difficult to study cellular mechanisms with the plants adapted to a natural stress. Studies on high light and UV loads may be split in two parts. Many reports describe natural UV as harmful for the plants, but these studies were mainly conducted by shielding off natural UV (as controls). Other experiments apply additional UV in the field and have had practically no negative impact on metabolism. The latter group is supported by the observations that green overwintering plants increase their flavonoids under snow even in the absence of

  16. Animal nutrition and breeding conditions modify the physiology of isolated primary cells.

    Science.gov (United States)

    Milisav, Irina; Banič, Blaž; Šuput, Dušan

    2017-05-01

    Animal primary cell cultures are widely used in biomedical research to investigate cell metabolism, diseases and to devise novel treatments. Modern animal breeding techniques are developed to unify, control and reduce the amount of microorganisms that the animals are being exposed to. Furthermore, health monitoring and strict caging and handling protocols allow animals to be exposed only to a selected spectrum of microbes. We are starting to appreciate that nutrition can influence composition of gut microbiota that can impact hosting organism's physiology and can even result in development of pathological changes. Evidence is also emerging that acute as well as chronic stresses can profoundly influence the physiology of certain organs, especially heart and liver. Our preliminary data imply that changes in animal nutrition and stress levels initiated up to minutes before the cell isolation could alter the cell stress response of cultured primary hepatocytes after isolation, leading to differences in sensitivity of apoptosis triggering. Therefore, we propose the hypothesis that conditions of animal breeding, especially diet and stress levels, are reflected in the physiology of the isolated primary cells. Variations in animal breeding conditions may influence experimental results on isolated cells and their applicability for studying human disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Combinations of physiologic estrogens with xenoestrogens alter ERK phosphorylation profiles in rat pituitary cells.

    Science.gov (United States)

    Jeng, Yow-Jiun; Watson, Cheryl S

    2011-01-01

    Estrogens are potent nongenomic phospho-activators of extracellular-signal-regulated kinases (ERKs). A major concern about the toxicity of xenoestrogens (XEs) is potential alteration of responses to physiologic estrogens when XEs are present simultaneously. We examined estrogen-induced ERK activation, comparing the abilities of structurally related XEs (alkylphenols and bisphenol A) to alter ERK responses induced by physiologic concentrations (1 nM) of estradiol (E2), estrone (E1), and estriol (E3). We quantified hormone/mimetic-induced ERK phosphorylations in the GH3/B6/F10 rat pituitary cell line using a plate immunoassay, comparing effects with those on cell proliferation and by estrogen receptor subtype-selective ligands. Alone, these structurally related XEs activate ERKs in an oscillating temporal pattern similar (but not identical) to that with physiologic estrogens. The potency of all estrogens was similar (active between femtomolar and nanomolar concentrations). XEs potently disrupted physiologic estrogen signaling at low, environmentally relevant concentrations. Generally, XEs potentiated (at the lowest, subpicomolar concentrations) and attenuated (at the highest, picomolar to 100 nM concentrations) the actions of the physiologic estrogens. Some XEs showed pronounced nonmonotonic responses/inhibitions. The phosphorylated ERK and proliferative responses to receptor-selective ligands were only partially correlated. XEs are both imperfect potent estrogens and endocrine disruptors; the more efficacious an XE, the more it disrupts actions of physiologic estrogens. This ability to disrupt physiologic estrogen signaling suggests that XEs may disturb normal functioning at life stages where actions of particular estrogens are important (e.g., development, reproductive cycling, pregnancy, menopause).

  18. Comparative mechanisms of cancer cell migration through 3D matrix and physiological microtracks.

    Science.gov (United States)

    Carey, Shawn P; Rahman, Aniqua; Kraning-Rush, Casey M; Romero, Bethsabe; Somasegar, Sahana; Torre, Olivia M; Williams, Rebecca M; Reinhart-King, Cynthia A

    2015-03-15

    Tumor cell invasion through the stromal extracellular matrix (ECM) is a key feature of cancer metastasis, and understanding the cellular mechanisms of invasive migration is critical to the development of effective diagnostic and therapeutic strategies. Since cancer cell migration is highly adaptable to physiochemical properties of the ECM, it is critical to define these migration mechanisms in a context-specific manner. Although extensive work has characterized cancer cell migration in two- and three-dimensional (3D) matrix environments, the migration program employed by cells to move through native and cell-derived microtracks within the stromal ECM remains unclear. We previously reported the development of an in vitro model of patterned type I collagen microtracks that enable matrix metalloproteinase-independent microtrack migration. Here we show that collagen microtracks closely resemble channel-like gaps in native mammary stroma ECM and examine the extracellular and intracellular mechanisms underlying microtrack migration. Cell-matrix mechanocoupling, while critical for migration through 3D matrix, is not necessary for microtrack migration. Instead, cytoskeletal dynamics, including actin polymerization, cortical tension, and microtubule turnover, enable persistent, polarized migration through physiological microtracks. These results indicate that tumor cells employ context-specific mechanisms to migrate and suggest that selective targeting of cytoskeletal dynamics, but not adhesion, proteolysis, or cell traction forces, may effectively inhibit cancer cell migration through preformed matrix microtracks within the tumor stroma. Copyright © 2015 the American Physiological Society.

  19. Cell physiology at the Mount Desert Island Biological Laboratory: a brief look back and forward

    Science.gov (United States)

    2011-01-01

    The Mount Desert Island Biological Laboratory (MDIBL) has played important roles in the development of modern physiological concepts and tools, particularly in the fields of kidney and epithelial cell physiology. Over the last decade, MDIBL has undergone remarkable growth and evolution. This article will briefly review MDIBL's past and outline its future directions. It is hoped that this overview will renew and stimulate interest in MDIBL and, in particular, will encourage an even wider community of physiologists to participate in its ongoing growth and development. PMID:21068363

  20. Design, Fabrication and Characterization of an In Silico Cell Physiology lab for Bio Sensing Applications

    International Nuclear Information System (INIS)

    Haque, A ul; Rokkam, M; De Carlo, A R; Wereley, S T; Wells, H W; McLamb, W T; Roux, S J; Irazoqui, P P; Porterfield, D M

    2006-01-01

    In this paper, we report the design, fabrication and characterization of an In Silico cell physiology biochip for measuring Ca 2+ ion concentrations and currents around single cells. This device has been designed around specific science objectives of measuring real time multidimensional calcium flux patterns around sixteen Ceratopteris richardii fern spores in microgravity flight experiments and ground studies. The sixteen microfluidic cell holding pores are 150 by 150 μm each and have 4 Ag/AgCl electrodes leading into them. An SU-8 structural layer is used for insulation and packaging purposes. The In Silico cell physiology lab is wire bonded on to a custom PCB for easy interface with a state of the art data acquisition system. The electrodes are coated with a Ca 2+ ion selective membrane based on ETH-5234 ionophore and operated against an Ag/AgCl reference electrode. Initial characterization results have shown Nernst slopes of 30mv/decade that were stable over a number of measurement cycles. While this work is focused on technology to enable basic research on the Ceratopteris richardii spores, we anticipate that this type of cell physiology lab-on-a-chip will be broadly applied in biomedical and pharmacological research by making minor modifications to the electrode material and the measurement technique. Future applications include detection of glucose, hormones such as plant auxin, as well as multiple analyte detection on the same chip

  1. Design, Fabrication and Characterization of an In Silico Cell Physiology lab for Bio Sensing Applications

    Energy Technology Data Exchange (ETDEWEB)

    Haque, A ul; Rokkam, M; De Carlo, A R; Wereley, S T; Wells, H W; McLamb, W T; Roux, S J; Irazoqui, P P; Porterfield, D M

    2006-04-01

    In this paper, we report the design, fabrication and characterization of an In Silico cell physiology biochip for measuring Ca{sup 2+} ion concentrations and currents around single cells. This device has been designed around specific science objectives of measuring real time multidimensional calcium flux patterns around sixteen Ceratopteris richardii fern spores in microgravity flight experiments and ground studies. The sixteen microfluidic cell holding pores are 150 by 150 {mu}m each and have 4 Ag/AgCl electrodes leading into them. An SU-8 structural layer is used for insulation and packaging purposes. The In Silico cell physiology lab is wire bonded on to a custom PCB for easy interface with a state of the art data acquisition system. The electrodes are coated with a Ca{sup 2+} ion selective membrane based on ETH-5234 ionophore and operated against an Ag/AgCl reference electrode. Initial characterization results have shown Nernst slopes of 30mv/decade that were stable over a number of measurement cycles. While this work is focused on technology to enable basic research on the Ceratopteris richardii spores, we anticipate that this type of cell physiology lab-on-a-chip will be broadly applied in biomedical and pharmacological research by making minor modifications to the electrode material and the measurement technique. Future applications include detection of glucose, hormones such as plant auxin, as well as multiple analyte detection on the same chip.

  2. Magnitude-dependent proliferation and contractility modulation of human bladder smooth muscle cells under physiological stretch.

    Science.gov (United States)

    Luo, De-Yi; Wazir, Romel; Du, Caigan; Tian, Ye; Yue, Xuan; Wei, Tang-Qiang; Wang, Kun-Jie

    2015-11-01

    The purpose of this study was to describe and test a kind of stretch pattern which is based on modified BOSE BioDynamic system to produce optimum physiological stretch during bladder cycle. Moreover, we aimed to emphasize the effects of physiological stretch's amplitude upon proliferation and contractility of human bladder smooth muscle cells (HBSMCs). HBSMCs were seeded onto silicone membrane and subjected to stretch simulating bladder cycle at the range of stretches and time according to customized software on modified BOSE BioDynamic bioreactor. Morphological changes were assessed using immunofluorescence and confocal laser scanning microscope. Cell proliferation and cell viability were determined by BrdU incorporation assay and Cell Counting Kit-8, respectively. Contractility of the cells was determined using collagen gel contraction assay. RT-PCR was used to assess phenotypic and contractility markers. HBSMCs were found to show morphologically spindle-shaped and orientation at various elongations in the modified bioreactor. Stretch-induced proliferation and viability depended on the magnitude of stretch, and stretches also regulate contractility and contraction markers in a magnitude-dependent manner. We described and tested a kind of stretch pattern which delivers physiological stretch implemented during bladder cycle. The findings also showed that mechanical stretch can promote magnitude-dependent morphological, proliferative and contractile modulation of HBSMCs in vitro.

  3. Synchronized mammalian cell culture: part I--a physical strategy for synchronized cultivation under physiological conditions.

    Science.gov (United States)

    Barradas, Oscar Platas; Jandt, Uwe; Becker, Max; Bahnemann, Janina; Pörtner, Ralf; Zeng, An-Ping

    2015-01-01

    Conventional analysis and optimization procedures of mammalian cell culture processes mostly treat the culture as a homogeneous population. Hence, the focus is on cell physiology and metabolism, cell line development, and process control strategy. Impact on cultivations caused by potential variations in cellular properties between different subpopulations, however, has not yet been evaluated systematically. One main cause for the formation of such subpopulations is the progress of all cells through the cell cycle. The interaction of potential cell cycle specific variations in the cell behavior with large-scale process conditions can be optimally determined by means of (partially) synchronized cultivations, with subsequent population resolved model analysis. Therefore, it is desirable to synchronize a culture with minimal perturbation, which is possible with different yield and quality using physical selection methods, but not with frequently used chemical or whole-culture methods. Conventional nonsynchronizing methods with subsequent cell-specific, for example, flow cytometric analysis, can only resolve cell-limited effects of the cell cycle. In this work, we demonstrate countercurrent-flow centrifugal elutriation as a useful physical method to enrich mammalian cell populations within different phases of a cell cycle, which can be further cultivated for synchronized growth in bioreactors under physiological conditions. The presented combined approach contrasts with other physical selection methods especially with respect to the achievable yield, which makes it suitable for bioreactor scale cultivations. As shown with two industrial cell lines (CHO-K1 and human AGE1.HN), synchronous inocula can be obtained with overall synchrony degrees of up to 82% in the G1 phase, 53% in the S phase and 60% in the G2/M phase, with enrichment factors (Ysync) of 1.71, 1.79, and 4.24 respectively. Cells are able to grow with synchrony in bioreactors over several cell cycles. This

  4. ARG1 Functions in the Physiological Adaptation of Undifferentiated Plant Cells to Spaceflight

    Science.gov (United States)

    Zupanska, Agata K.; Schultz, Eric R.; Yao, JiQiang; Sng, Natasha J.; Zhou, Mingqi; Callaham, Jordan B.; Ferl, Robert J.; Paul, Anna-Lisa

    2017-11-01

    Scientific access to spaceflight and especially the International Space Station has revealed that physiological adaptation to spaceflight is accompanied or enabled by changes in gene expression that significantly alter the transcriptome of cells in spaceflight. A wide range of experiments have shown that plant physiological adaptation to spaceflight involves gene expression changes that alter cell wall and other metabolisms. However, while transcriptome profiling aptly illuminates changes in gene expression that accompany spaceflight adaptation, mutation analysis is required to illuminate key elements required for that adaptation. Here we report how transcriptome profiling was used to gain insight into the spaceflight adaptation role of Altered response to gravity 1 (Arg1), a gene known to affect gravity responses in plants on Earth. The study compared expression profiles of cultured lines of Arabidopsis thaliana derived from wild-type (WT) cultivar Col-0 to profiles from a knock-out line deficient in the gene encoding ARG1 (ARG1 KO), both on the ground and in space. The cell lines were launched on SpaceX CRS-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC-17 spaceflight mission. The cultured cell lines were grown within 60 mm Petri plates in Petri Dish Fixation Units (PDFUs) that were housed within the Biological Research In Canisters (BRIC) hardware. Spaceflight samples were fixed on orbit. Differentially expressed genes were identified between the two environments (spaceflight and comparable ground controls) and the two genotypes (WT and ARG1 KO). Each genotype engaged unique genes during physiological adaptation to the spaceflight environment, with little overlap. Most of the genes altered in expression in spaceflight in WT cells were found to be Arg1-dependent, suggesting a major role for that gene in the physiological adaptation of undifferentiated cells to spaceflight.

  5. Probing the physiological state of phytoplankton at the single-cell level

    Directory of Open Access Journals (Sweden)

    Frank J. Jochem

    2000-06-01

    Full Text Available Probing the physiological state of phytoplankton at the single-cell level provides valuable insight in ecological studies as well as in environmental monitoring of pollution or UV impacts. This paper reviews the recent progress in assessing the physiological state of phytoplankton with flow cytometry by inherent cell properties such as cell size and chlorophyll autofluorescence, specific fluorescent dyes, and newly developed molecular probes and enzyme substrates. It is reported how nitrogen and iron limitation as well as the effect of copper pollution could be derived from changes in cell inherent properties. Effects of Cu were also recorded by monitoring cell membrane potentials and esterase activity. Photosynthetic capacity of algae was assessed by changes in chlorophyll fluorescence with the electron transport inhibitor DCMU, by a cytometric adaptation of the pump-and-probe approach, and molecular probes for Rubisco. Antibodies were also applied to mark non-terminal stages in the cell DNA replication cycle, to detect non-proliferating cells, to assess DNA damage caused by UV-B radiation and to quantify diatom stickiness. Fluorescein diacetate proved useful to discriminate metabolically active from inactive cells and to reveal strategies of dark survival in algae. The activity of alkaline phosphatase was recorded by a new fluorigenic substrate ELF, and polyclonal antibodies against nitrate reductase (NR provided measurements of the NR abundance. An outlook will show how recent developments in molecular probes might affect the future analysis of marine ecosystems and their communities.

  6. Environmental temperature affects physiology and survival of nanosecond pulsed electric field-treated cells.

    Science.gov (United States)

    Yin, Shengyong; Miao, Xudong; Zhang, Xueming; Chen, Xinhua; Wen, Hao

    2018-02-01

    Nanosecond pulsed electric field (nsPEF) is a novel non-thermal tumor ablation technique. However, how nsPEF affect cell physiology at different environmental temperature is still kept unknown. But this issue is of critical clinical practice relevance. This work aim to investigate how nsPEF treated cancer cells react to different environmental temperatures (0, 4, 25, and 37°C). Their cell viability, apoptosis, mitochondrial membrane potential, and reactive oxygen species (ROS) were examined. Lower temperature resulted in higher apoptosis rate, decreased mitochondria membrane potential, and increased ROS levels. Sucrose and N-acetylcysteine (NAC) pre-incubation inhibit ROS generation and increase cell survival, protecting nsPEF-treated cells from low temperature-caused cell death. This work provides an experimental basis for hypothermia and fluid transfusion during nsPEF ablation with anesthesia. © 2017 Wiley Periodicals, Inc.

  7. Na+ -K+ -2Cl- Cotransporter (NKCC) Physiological Function in Nonpolarized Cells and Transporting Epithelia.

    Science.gov (United States)

    Delpire, Eric; Gagnon, Kenneth B

    2018-03-25

    Two genes encode the Na + -K + -2Cl - cotransporters, NKCC1 and NKCC2, that mediate the tightly coupled movement of 1Na + , 1K + , and 2Cl - across the plasma membrane of cells. Na + -K + -2Cl - cotransport is driven by the chemical gradient of the three ionic species across the membrane, two of them maintained by the action of the Na + /K + pump. In many cells, NKCC1 accumulates Cl - above its electrochemical potential equilibrium, thereby facilitating Cl - channel-mediated membrane depolarization. In smooth muscle cells, this depolarization facilitates the opening of voltage-sensitive Ca 2+ channels, leading to Ca 2+ influx, and cell contraction. In immature neurons, the depolarization due to a GABA-mediated Cl - conductance produces an excitatory rather than inhibitory response. In many cell types that have lost water, NKCC is activated to help the cells recover their volume. This is specially the case if the cells have also lost Cl - . In combination with the Na + /K + pump, the NKCC's move ions across various specialized epithelia. NKCC1 is involved in Cl - -driven fluid secretion in many exocrine glands, such as sweat, lacrimal, salivary, stomach, pancreas, and intestine. NKCC1 is also involved in K + -driven fluid secretion in inner ear, and possibly in Na + -driven fluid secretion in choroid plexus. In the thick ascending limb of Henle, NKCC2 activity in combination with the Na + /K + pump participates in reabsorbing 30% of the glomerular-filtered Na + . Overall, many critical physiological functions are maintained by the activity of the two Na + -K + -2Cl - cotransporters. In this overview article, we focus on the functional roles of the cotransporters in nonpolarized cells and in epithelia. © 2018 American Physiological Society. Compr Physiol 8:871-901, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

  8. Physiological Gut Oxygenation Alters GLP-1 Secretion from the Enteroendocrine Cell Line STC-1.

    Science.gov (United States)

    Kondrashina, Alina; Papkovsky, Dmitri; Giblin, Linda

    2018-02-01

    Enteroendocrine cell lines are routinely assayed in simple buffers at ≈20% oxygen to screen foods for bioactives that boost satiety hormone levels. However, in vivo, enteroendocrine cells are exposed to different phases of food digestion and function at low oxygen concentration, ranging from 7.5% in the stomach to 0.5% in the colon-rectal junction. The objective of this study is to investigate the effect of physiologically relevant O 2 concentrations of the gut on the production and secretion of the satiety hormone, glucagon-like peptide 1 (GLP-1), from the murine enteroendocrine cell line, secretin tumor cell line (STC-1), in response to dairy macronutrients as they transit the gut. GLP-1 exocytosis from STC-1 cells is influenced by both oxygen concentration and by individual macronutrients. At low oxygen, STC-1 cell viability is significantly improved for all macronutrient stimulations and cyclic adenosine monophosphate levels are dampened. GLP-1 secretion from STC-1 cells is influenced by both the phase of yogurt digestion and corresponding O 2 concentration. Atmospheric oxygen at 4.5% combined with upper gastric digesta, which simulates ileum conditions, yields the highest GLP-1 response. This demonstrates the importance of considering physiological oxygen levels and food digestion along gastrointestinal tract for reliable in vitro analysis of gut hormone secretion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Quorum sensing influences phage infection efficiency via affecting cell population and physiological state.

    Science.gov (United States)

    Qin, Xuying; Sun, Qinghui; Yang, Baixue; Pan, Xuewei; He, Yang; Yang, Hongjiang

    2017-02-01

    Bacterial growth phase has been reported affecting phage infection. To underpin the related mechanism, infection efficiency of Pseudomonas aeruginosa phage K5 is characterized. When infecting the logarithmic cells, phage K5 produced significantly more infection centers than the stationary cells, well concordant with the viable cell ratio in the different growth phases. Additionally, the burst size decreased dramatically in the stationary cells, implying that the physiological state of the viable cells contributed to the productivity of phage K5, and it was consistent with the expression variation of the phage RNA polymerase. Quorum sensing inhibitor penicillic acid was applied and could significantly improve the viable cell proportion and the infection center numbers, but had less effect on the corresponding burst sizes. Moreover, the effect of penicillic acid and the quorum sensing regulator mutants on the production of phage C11 was also analyzed. Taken together, our data suggest that quorum sensing is involved in the defense of phage K5 infection by influencing the viable cell population and their physiological state, and it is an efficient and intrinsic pathway allowing bacteria to resist phage attacks in natural environment. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Physiological responses to acid stress by Saccharomyces cerevisiae when applying high initial cell density

    Science.gov (United States)

    2016-01-01

    High initial cell density is used to increase volumetric productivity and shorten production time in lignocellulosic hydrolysate fermentation. Comparison of physiological parameters in high initial cell density cultivation of Saccharomyces cerevisiae in the presence of acetic, formic, levulinic and cinnamic acids demonstrated general and acid-specific responses of cells. All the acids studied impaired growth and inhibited glycolytic flux, and caused oxidative stress and accumulation of trehalose. However, trehalose may play a role other than protecting yeast cells from acid-induced oxidative stress. Unlike the other acids, cinnamic acid did not cause depletion of cellular ATP, but abolished the growth of yeast on ethanol. Compared with low initial cell density, increasing initial cell density reduced the lag phase and improved the bioconversion yield of cinnamic acid during acid adaptation. In addition, yeast cells were able to grow at elevated concentrations of acid, probable due to the increase in phenotypic cell-to-cell heterogeneity in large inoculum size. Furthermore, the specific growth rate and the specific rates of glucose consumption and metabolite production were significantly lower than at low initial cell density, which was a result of the accumulation of a large fraction of cells that persisted in a viable but non-proliferating state. PMID:27620460

  11. Mineralization of bone-related SaOS-2 cells under physiological hypoxic conditions.

    Science.gov (United States)

    Müller, Werner E G; Schröder, Heinz C; Tolba, Emad; Diehl-Seifert, Bärbel; Wang, Xiaohong

    2016-01-01

    Inorganic polyphosphate (polyP) is a physiological energy-rich polymer with multiple phosphoric anhydride bonds. In cells such as bone-forming osteoblasts, glycolysis is the main pathway generating metabolic energy in the form of ATP. In the present study, we show that, under hypoxic culture conditions, the growth/viability of osteoblast-like SaOS-2 cells is not impaired. The addition of polyP to those cells, administered as amorphous calcium polyP nanoparticles (aCa-polyP-NP; approximate size 100 nm), significantly increased the proliferation of the cells. In the presence of polyP, the cells produce significant levels of lactate, the end product of anaerobic glycolysis. Under those conditions, an eight-fold increase in the steady-state level of the membrane-associated carbonic anhydrase IX is found, as well as a six-fold induction of the hypoxia-inducible factor 1. Consequently, biomineral formation onto the SaOS-2 cells decreases under low oxygen tension. If the polyP nanoparticles are added to the cells, the degree of mineralization is enhanced. These changes had been measured also in human mesenchymal stem cells. The assumption that the bicarbonate, generated by the carbonic anhydrase in the presence of polyP under low oxygen, is deposited as a constituent of the bioseeds formed during initial hydroxyapatite formation is corroborated by the identification of carbon besides of calcium, oxygen and phosphorus in the initial biomineral deposit onto the cells using the sensitive technology of high-resolution energy dispersive spectrometry mapping. Based on these data, we conclude that polyP is required for the supply of metabolic energy during bone mineral formation under physiological, hypoxic conditions, acting as a 'metabolic fuel' for the cells to grow. © 2015 FEBS.

  12. [The Influence of Different Ionic Concentration in Cell Physiological Solution on Temperature Measurement by Near Infrared].

    Science.gov (United States)

    Zheng, Yu; Chen, Xiong; Zhou, Mei; Wang, Meng-jun; Wang, Jin-hai; Li, Gang; Cui, Jun

    2015-10-01

    It is important to real-timely monitor and control the temperature of cell physiological solution in patch clamp experiments, which can eliminate the uncertainty due to temperature and improve the measurement accuracy. This paper studies the influence of different ions at different concentrations in the physiological solution on precision of a temperature model by using near infrared spectroscopy and chemometrics method. Firstly, we prepared twelve sample solutions respectively with the solutes of CaCl2, KCl and NaCl at four kinds of concentrations, and collected the spectra of different solutions at the setting temperature range 20-40 degrees C, the range of the spectra is 9 615-5 714 cm(-1). Then we divided the spectra of each solution at different temperatures into two parts (a training set and a prediction set) by three methods. Interval partial least squares method was used to select an effective wavelength range and develop calibration models between the spectra in the selected range and temperature velues. The experimental results show that RMSEP of CaCl2 solution with 0.25 g x mL(-1) is maximum, the result of the three tests are 0.386 3, 0.303 7 and 0.337 2 degrees C, RMSEP of NaCl with 0.005 g x mL(-1) solution is minimum, the result of the three tests are 0.220 8, 0.155 3 and 0.145 2 degrees C. The experimental results indicate that Ca2+ has the greatest influence on the accuracy of the temperature model of the cell physiological solution, then K+, and Na+ has the least influence. And with the ionic concentration increasing, the model accuracy decreases. Therefore; when we build the temperature model of cell physiological solution, it is necessary to change the proportion of the three kinds of main ions in cell physiological solution reasonably in order to correct the effects of different ionic concentrations in physiological solution and improve the accuracy of temperature measurements by near infrared spectroscopy.

  13. Repetitive Supra-Physiological Shear Stress Impairs Red Blood Cell Deformability and Induces Hemolysis.

    Science.gov (United States)

    Horobin, Jarod T; Sabapathy, Surendran; Simmonds, Michael J

    2017-11-01

    The supra-physiological shear stress that blood is exposed to while traversing mechanical circulatory assist devices affects the physical properties of red blood cells (RBCs), impairs RBC deformability, and may induce hemolysis. Previous studies exploring RBC damage following exposure to supra-physiological shear stress have employed durations exceeding clinical instrumentation, thus we explored changes in RBC deformability following exposure to shear stress below the reported "hemolytic threshold" using shear exposure durations per minute (i.e., duty-cycles) reflective of that employed by circulatory assist devices. Blood collected from 20 male donors, aged 18-38 years, was suspended in a viscous medium and exposed to an intermittent shear stress protocol of 1 s at 100 Pa, every 60 s for 60 duty-cycles. During the remaining 59 s/min, the cells were left at stasis until the subsequent duty-cycle commenced. At discrete time points (15/30/45/60 duty-cycles), an ektacytometer measured RBC deformability immediately after shear exposure at 100 Pa. Plasma-free hemoglobin, a measurement of hemolysis, was quantified via spectrophotometry. Supra-physiological shear stress impaired RBC properties, as indicated by: (1) decreased maximal elongation of RBCs at infinite shear stress following 15 duty-cycles (P supra-physiological shear stress protocol (100 Pa) following exposure to 1 duty-cycle (F (1.891, 32.15) = 12.21, P = 0.0001); and (3) increased plasma-free hemoglobin following 60 duty-cycles (P supra-physiological shear stress, impairs RBC deformability, with the extent of impairment exacerbated with each duty-cycle, and ultimately precipitates hemolysis. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  14. Microfluidic device for rapid solution exchange to study kinetics of cell physiology

    Science.gov (United States)

    Hu, Howard; Honnatti, Meghana; Gillis, Kevin

    2006-11-01

    Exchanging the extracellular solution of the cell rapidly (less than 10ms) is an important requirement in study the kinetics of cell physiology. A microfluidic device is developed to exchange the solution around the cells as they flow through a junction at the intersection of two microfluidic channels. The solution exchange time is measured experimentally by fluorescently labeling the cell surface membranes with a styryl dye, FM1-43 or FM 2-10, and then observing the time course of cell fluorescence decay following the rapid drop in the extracellular concentration of the FM dye that occurs as the cell flows past the fluidic junction. A numerical model is developed to guide the experimental design of microfluidic device. In the model, the motion of a single cell through a fluid junction is simulated and the mixing process of the solutions is solved. The model also includes the kinetics of departitioning of FM dyes from the cell membrane. The departitioning time constants for the FM dyes are determined from fitting the measured data of the cell fluorescence decay. This departitioning kinetics is important as FM dyes are commonly used to label cell membranes for the purpose of measuring the release of neurotransmitter from synaptic vesicles via exocytosis and the subsequent reuptake of vesicular membrane by endocytosis.

  15. Keeping the intracellular vitamin C at a physiologically relevant level in endothelial cell culture

    DEFF Research Database (Denmark)

    Frikke-Schmidt, Henriette Rønne; Lykkesfeldt, Jens

    2010-01-01

    It is generally accepted that the addition of vitamin C to cell culture medium improves cell growth. However, once added, the vitamin C concentration declines rapidly. This situation differs from the in vivo environment where the endothelium is constantly supplied with ascorbate from the blood....... With a focus on intracellular vitamin C, we simulated constant supply of ascorbate by the hourly addition of freshly prepared medium containing 75 lM ascorbate and subsequently compared it with more practical regimens using combinations of ascorbate and 2-phosphoascorbate. We found that a single supplement...... of ascorbate and 2-phosphoascorbate adequately maintains intracellular vitamin C at physiological levels for up to 72 h....

  16. Extracellular Membrane Vesicles as Vehicles for Brain Cell-to-Cell Interactions in Physiological as well as Pathological Conditions

    Directory of Open Access Journals (Sweden)

    Gabriella Schiera

    2015-01-01

    Full Text Available Extracellular vesicles are involved in a great variety of physiological events occurring in the nervous system, such as cross talk among neurons and glial cells in synapse development and function, integrated neuronal plasticity, neuronal-glial metabolic exchanges, and synthesis and dynamic renewal of myelin. Many of these EV-mediated processes depend on the exchange of proteins, mRNAs, and noncoding RNAs, including miRNAs, which occurs among glial and neuronal cells. In addition, production and exchange of EVs can be modified under pathological conditions, such as brain cancer and neurodegeneration. Like other cancer cells, brain tumours can use EVs to secrete factors, which allow escaping from immune surveillance, and to transfer molecules into the surrounding cells, thus transforming their phenotype. Moreover, EVs can function as a way to discard material dangerous to cancer cells, such as differentiation-inducing proteins, and even drugs. Intriguingly, EVs seem to be also involved in spreading through the brain of aggregated proteins, such as prions and aggregated tau protein. Finally, EVs can carry useful biomarkers for the early diagnosis of diseases. Herein we summarize possible roles of EVs in brain physiological functions and discuss their involvement in the horizontal spreading, from cell to cell, of both cancer and neurodegenerative pathologies.

  17. Physiological Hypoxia Enhances Stemness Preservation, Proliferation, and Bidifferentiation of Induced Hepatic Stem Cells

    Directory of Open Access Journals (Sweden)

    Xiaosong Zhi

    2018-01-01

    Full Text Available Induced hepatic stem cells (iHepSCs have great potential as donors for liver cell therapy due to their self-renewal and bipotential differentiation properties. However, the efficiency of bidifferentiation and repopulation efficiency of iHepSCs is relatively low. Recent evidence shows that physiological hypoxia, a vital factor within stem cell “niche” microenvironment, plays key roles in regulating tissue stem cell biological behaviors including proliferation and differentiation. In this study, we found that physiological hypoxia (10% O2 enhanced the stemness properties and promoted the proliferation ability of iHepSCs by accelerating G1/S transition via p53-p21 signaling pathway. In addition, short-term hypoxia preconditioning improved the efficiency of hepatic differentiation of iHepSCs, and long-term hypoxia promoted cholangiocytic differentiation but inhibited hepatic differentiation of iHepSCs. These results demonstrated the potential effects of hypoxia on stemness preservation, proliferation, and bidifferentiation of iHepSCs and promising perspective to explore appropriate culture conditions for therapeutic stem cells.

  18. Implications of Schwann Cells Biomechanics and Mechanosensitivity for Peripheral Nervous System Physiology and Pathophysiology

    Directory of Open Access Journals (Sweden)

    Gonzalo Rosso

    2017-10-01

    Full Text Available The presence of bones around the central nervous system (CNS provides it with highly effective physiologically crucial mechanical protection. The peripheral nervous system (PNS, in contrast, lacks this barrier. Consequently, the long held belief is that the PNS is mechanically vulnerable. On the other hand, the PNS is exposed to a variety of physiological mechanical stresses during regular daily activities. This fact prompts us to question the dogma of PNS mechanical vulnerability. As a matter of fact, impaired mechanics of PNS nerves is associated with neuropathies with the liability to mechanical stresses paralleled by significant impairment of PNS physiological functions. Our recent biomechanical integrity investigations on nerve fibers from wild-type and neuropathic mice lend strong support in favor of natural mechanical protection of the PNS and demonstrate a key role of Schwann cells (SCs therein. Moreover, recent works point out that SCs can sense mechanical properties of their microenvironment and the evidence is growing that SCs mechanosensitivity is important for PNS development and myelination. Hence, SCs exhibit mechanical strength necessary for PNS mechanoprotection as well as mechanosensitivity necessary for PNS development and myelination. This mini review reflects on the intriguing dual ability of SCs and implications for PNS physiology and pathophysiology.

  19. Physiological Plasticity of Neural-Crest-Derived Stem Cells in the Adult Mammalian Carotid Body.

    Science.gov (United States)

    Annese, Valentina; Navarro-Guerrero, Elena; Rodríguez-Prieto, Ismael; Pardal, Ricardo

    2017-04-18

    Adult stem cell plasticity, or the ability of somatic stem cells to cross boundaries and differentiate into unrelated cell types, has been a matter of debate in the last decade. Neural-crest-derived stem cells (NCSCs) display a remarkable plasticity during development. Whether adult populations of NCSCs retain this plasticity is largely unknown. Herein, we describe that neural-crest-derived adult carotid body stem cells (CBSCs) are able to undergo endothelial differentiation in addition to their reported role in neurogenesis, contributing to both neurogenic and angiogenic processes taking place in the organ during acclimatization to hypoxia. Moreover, CBSC conversion into vascular cell types is hypoxia inducible factor (HIF) dependent and sensitive to hypoxia-released vascular cytokines such as erythropoietin. Our data highlight a remarkable physiological plasticity in an adult population of tissue-specific stem cells and could have impact on the use of these cells for cell therapy. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  20. Six-frame picosecond radiation camera based on hydrated electron photoabsorption phenomena. [Laser opacity pattern in acidic aqueous cell formed by pulsed irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Coutts, G.W.; Olk, L.B.; Gates, H.A.; St. Leger-Barter, G.

    1977-01-15

    To obtain picosecond photographs of nanosecond radiation sources, a six-frame ultra-high speed radiation camera based on hydrated electron absorption phenomena has been developed. A time-dependent opacity pattern is formed in an acidic aqueous cell by a pulsed radiation source. Six time-resolved picosecond images of this changing opacity pattern are transferred to photographic film with the use of a mode-locked dye laser and six electronically gated microchannel plate image intensifiers. Because the lifetime of the hydrated electron absorption centers can be reduced to picoseconds, the opacity patterns represent time-space pulse profile images.

  1. A numerical investigation on multi-phase transport phenomena in a proton exchange membrane fuel cell stack

    Energy Technology Data Exchange (ETDEWEB)

    Le, Anh Dinh; Zhou, Biao [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Ave., Windsor, ON (Canada)

    2010-08-15

    In this study, the simulation of a fuel cell stack is performed by applying a general numerical model with VOF method that has been successfully applied to single PEMFC model to investigate the fluid dynamics, mass transport, flooding phenomenon and the effects of liquid water on the stack performance. The performance of three single cells in series connection in the fuel cell stack is examined according to the presence of liquid water in different single cells. The distributions of fluid flow, species concentration and the current density are presented to illustrate the effects of liquid water on the performance of each single cell. The numerical results locate that the low distributions of species in the flooding cell certainly degrade the performance of this cell. Moreover, it can be seen that the performance of the flooding cell will significantly affect the whole stack performance since the values of average current density must be identical in all single cells. (author)

  2. Normal rat kidney cells secrete both phosphorylated and nonphosphorylated forms of osteopontin showing different physiological properties

    International Nuclear Information System (INIS)

    Nemir, M.; DeVouge, M.W.; Mukherjee, B.B.

    1989-01-01

    We have reported previously that the 69-kDa major phosphoprotein, secreted by normal rat kidney (NRK) cells, is osteopontin, a glycosylated bone matrix protein. Here we show that this 69-kDa osteopontin is secreted by NRK cells in both phosphorylated (pp69) and nonphosphorylated (np69) forms, with estimated isoelectric points of 3.8 and 4.5, respectively. Electrophoretic analysis of radioiodinated cell surface proteins immunoprecipitated with an anti-69-kDa osteopontin serum, demonstrates that the 69-kDa osteopontin is also present on the cell surface, but only its phosphorylated form (pp69) shows such cell surface association. Because osteopontin mediates cell adhesion and spreading, and contains an Arg-Gly-Asp-Ser cell-binding sequence, our observations strongly suggest that the cell surface localization of pp69 osteopontin is receptor-mediated, and the modification by phosphorylation may be crucial for its receptor binding activity. We also report that antisera directed against either fibronectin or 69-kDa osteopontin co-immunoprecipitate both np69 osteopontin and fibronectin as a heat-dissociable complex. In contrast, pp69 osteopontin does not co-precipitate with fibronectin. Furthermore, compared to NRK cells, vanadyl sulfate-treated NRK cells which acquire a reversible transformed phenotype, including anchorage-independent growth, show increased levels of pp69 on the cell surface, concomitant with significantly decreased levels of pp69 and elevated levels of np69 in the conditioned media. The data presented here establish transformation sensitivity of NRK cell-secreted osteopontin with respect to its secretion and cell surface localization, and demonstrate that phosphorylated and nonphosphorylated forms of osteopontin have different physiological properties, which may regulate the functional roles of this extracellular matrix protein

  3. Adaptation of endothelial cells to physiologically-modeled, variable shear stress.

    Directory of Open Access Journals (Sweden)

    Joseph S Uzarski

    Full Text Available Endothelial cell (EC function is mediated by variable hemodynamic shear stress patterns at the vascular wall, where complex shear stress profiles directly correlate with blood flow conditions that vary temporally based on metabolic demand. The interactions of these more complex and variable shear fields with EC have not been represented in hemodynamic flow models. We hypothesized that EC exposed to pulsatile shear stress that changes in magnitude and duration, modeled directly from real-time physiological variations in heart rate, would elicit phenotypic changes as relevant to their critical roles in thrombosis, hemostasis, and inflammation. Here we designed a physiological flow (PF model based on short-term temporal changes in blood flow observed in vivo and compared it to static culture and steady flow (SF at a fixed pulse frequency of 1.3 Hz. Results show significant changes in gene regulation as a function of temporally variable flow, indicating a reduced wound phenotype more representative of quiescence. EC cultured under PF exhibited significantly higher endothelial nitric oxide synthase (eNOS activity (PF: 176.0±11.9 nmol/10(5 EC; SF: 115.0±12.5 nmol/10(5 EC, p = 0.002 and lower TNF-a-induced HL-60 leukocyte adhesion (PF: 37±6 HL-60 cells/mm(2; SF: 111±18 HL-60/mm(2, p = 0.003 than cells cultured under SF which is consistent with a more quiescent anti-inflammatory and anti-thrombotic phenotype. In vitro models have become increasingly adept at mimicking natural physiology and in doing so have clarified the importance of both chemical and physical cues that drive cell function. These data illustrate that the variability in metabolic demand and subsequent changes in perfusion resulting in constantly variable shear stress plays a key role in EC function that has not previously been described.

  4. Mushroom body miscellanea: transgenic Drosophila strains expressing anatomical and physiological sensor proteins in Kenyon cells

    Science.gov (United States)

    Pech, Ulrike; Dipt, Shubham; Barth, Jonas; Singh, Priyanka; Jauch, Mandy; Thum, Andreas S.; Fiala, André; Riemensperger, Thomas

    2013-01-01

    The fruit fly Drosophila melanogaster represents a key model organism for analyzing how neuronal circuits regulate behavior. The mushroom body in the central brain is a particularly prominent brain region that has been intensely studied in several insect species and been implicated in a variety of behaviors, e.g., associative learning, locomotor activity, and sleep. Drosophila melanogaster offers the advantage that transgenes can be easily expressed in neuronal subpopulations, e.g., in intrinsic mushroom body neurons (Kenyon cells). A number of transgenes has been described and engineered to visualize the anatomy of neurons, to monitor physiological parameters of neuronal activity, and to manipulate neuronal function artificially. To target the expression of these transgenes selectively to specific neurons several sophisticated bi- or even multipartite transcription systems have been invented. However, the number of transgenes that can be combined in the genome of an individual fly is limited in practice. To facilitate the analysis of the mushroom body we provide a compilation of transgenic fruit flies that express transgenes under direct control of the Kenyon-cell specific promoter, mb247. The transgenes expressed are fluorescence reporters to analyze neuroanatomical aspects of the mushroom body, proteins to restrict ectopic gene expression to mushroom bodies, or fluorescent sensors to monitor physiological parameters of neuronal activity of Kenyon cells. Some of the transgenic animals compiled here have been published already, whereas others are novel and characterized here for the first time. Overall, the collection of transgenic flies expressing sensor and reporter genes in Kenyon cells facilitates combinations with binary transcription systems and might, ultimately, advance the physiological analysis of mushroom body function. PMID:24065891

  5. A bio-inspired glucose controller based on pancreatic β-cell physiology.

    Science.gov (United States)

    Herrero, Pau; Georgiou, Pantelis; Oliver, Nick; Johnston, Desmond G; Toumazou, Christofer

    2012-05-01

    Control algorithms for closed-loop insulin delivery in type 1 diabetes have been mainly based on control engineering or artificial intelligence techniques. These, however, are not based on the physiology of the pancreas but seek to implement engineering solutions to biology. Developments in mathematical models of the β-cell physiology of the pancreas have described the glucose-induced insulin release from pancreatic β cells at a molecular level. This has facilitated development of a new class of bio-inspired glucose control algorithms that replicate the functionality of the biological pancreas. However, technologies for sensing glucose levels and delivering insulin use the subcutaneous route, which is nonphysiological and introduces some challenges. In this article, a novel glucose controller is presented as part of a bio-inspired artificial pancreas. A mathematical model of β-cell physiology was used as the core of the proposed controller. In order to deal with delays and lack of accuracy introduced by the subcutaneous route, insulin feedback and a gain scheduling strategy were employed. A United States Food and Drug Administration-accepted type 1 diabetes mellitus virtual population was used to validate the presented controller. Premeal and postmeal mean ± standard deviation blood glucose levels for the adult and adolescent populations were well within the target range set for the controller [(70, 180) mg/dl], with a percent time in range of 92.8 ± 7.3% for the adults and 83.5 ± 14% for the adolescents. This article shows for the first time very good glucose control in a virtual population with type 1 diabetes mellitus using a controller based on a subcellular β-cell model. © 2012 Diabetes Technology Society.

  6. The importance of cell physiology to the performance of animal cell bioreactors.

    Science.gov (United States)

    Runstadler, P W

    1992-10-13

    This report has pointed out the following: (1) the new animal cell products that will be produced commercially will have large dollar markets and will, together with cost containment and competitive pressures, place a greater emphasis on the reduction of the cost of production through the selection of appropriate culture technology; (2) the benefits to be gained by working with basic biological processes in animal cell culture that will increase cell density, cell productivity, and product quality; (3) the need to work with reactor technologies that can affect the basic biology of the cell in these positive ways; (4) it appears worthwhile to explore immobilized, high cell density culture technologies as a possible means to achieve the objectives by affecting the basic regulation of the cell through fundamental cell/cell environment biological processes.

  7. Interferon-gamma sensitizes colonic epithelial cell lines to physiological and therapeutic inducers of colonocyte apoptosis.

    LENUS (Irish Health Repository)

    O'Connell, J

    2012-02-03

    Homeostasis in the colonic epithelium is achieved by a continuous cycle of proliferation and apoptosis, in which imbalances are associated with disease. Inflammatory bowel disease (IBD) and colon cancer are associated with either excessive or insufficient apoptosis of colonic epithelial cells, respectively. By using two colonic epithelial cell lines, HT29 and SW620, we investigated how the epithelial cell\\'s sensitivity to apoptosis was regulated by the proinflammatory cytokine interferon-gamma (IFN-gamma). We found that IFN-gamma sensitized HT29 cells, and to a lesser extent SW620, to diverse inducers of apoptosis of physiologic or therapeutic relevance to the colon. These apoptosis inducers included Fas (CD95\\/APO-1) ligand (FasL), short-chain fatty acids, and chemotherapeutic drugs. The extent of IFN-gamma-mediated apoptosis sensitization in these two cell lines correlated well with the degree of IFN-gamma-mediated upregulation of the proapoptotic protease caspase-1. Although IFN-gamma alone effectively sensitized HT29 cells to apoptosis, inclusion of the protein synthesis inhibitor cyclohexamide (CHX) during apoptotic challenge was necessary for maximal sensitization of SW620. The requirement of CHX to sensitize SW620 cells to apoptosis implies a need to inhibit translation of antiapoptotic proteins absent from HT29. In particular, the antiapoptotic protein Bcl-2 was strongly expressed in SW620 cells but absent from HT29. Our results indicate that IFN-gamma increases the sensitivity of colonic epithelial cells to diverse apoptotic stimuli in concert, via upregulation of caspase-1. Our findings implicate caspase-1 and Bcl-2 as important central points of control determining the general sensitivity of colonic epithelial cells to apoptosis.

  8. Novel magnesium alloy Mg–2La caused no cytotoxic effects on cells in physiological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weizbauer, Andreas, E-mail: weizbauer.andreas@mh-hannover.de [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); CrossBIT, Center for Biocompatibility and Implant-Immunology, Department of Orthopedic Surgery, Hannover Medical School, Feodor-Lynen-Str. 31, 30625 Hannover (Germany); Seitz, Jan-Marten [Institute of Materials Science, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen (Germany); Werle, Peter [ABB AG, Trafoweg 4, 06112 Halle (Germany); Hegermann, Jan [Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover (Germany); Willbold, Elmar [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); CrossBIT, Center for Biocompatibility and Implant-Immunology, Department of Orthopedic Surgery, Hannover Medical School, Feodor-Lynen-Str. 31, 30625 Hannover (Germany); Eifler, Rainer [Institute of Materials Science, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen (Germany); Windhagen, Henning [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); Reifenrath, Janin [Small Animal Clinic, University of Veterinary Medicine Hannover, Bünteweg 9, 30559 Hannover (Germany); Waizy, Hazibullah [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany)

    2014-08-01

    Using several different in vitro assays, a new biodegradable magnesium alloy Mg–2La, composed of 98% magnesium and 2% lanthanum, was investigated as a possible implant material for biomedical applications. An in vitro cytotoxicity test, according to EN ISO 10993-5/12, with L929 and human osteoblastic cells identified no toxic effects on cell viability at physiological concentrations (at 50% dilutions and higher). The metabolic activity of human osteoblasts in the 100% extract was decreased to < 70% and was therefore rated as cytotoxic. The degradation rates of Mg–2La were evaluated in phosphate buffered saline and four different cell culture media. The degradation rates were shown to be influenced by the composition of the solution, and the addition of fetal bovine serum slightly accelerated the corrosive process. The results of these in vitro experiments suggest that Mg–2La is a promising candidate for use as an orthopedic implant material. - Highlights: • A new magnesium alloy (Mg–2La) has been developed. • Magnesium alloy Mg–2La revealed no toxic effect in physiological concentrations. • Degradation rates were influenced by the corrosion media. • The addition of fetal bovine serum increased the corrosive process slightly.

  9. A CFD analysis of transport phenomena and electrochemical reactions in a tubular-shaped PEM fuel cell

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2013-01-01

    A fuel cell is most interesting new power source because it solves not only the environment problem but also natural resource exhaustion problem. CFD modeling and simulation for heat and mass transport in PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal co...

  10. Development of a screening approach for exploring cell factory potential through metabolic flux analysis and physiology

    DEFF Research Database (Denmark)

    Knudsen, Peter Boldsen; Nielsen, Kristian Fog; Thykær, Jette

    2012-01-01

    of the recombinant strains in order to evaluate their potential as fungal cell factories and for guiding further metabolic engineering strategies. To meet the demand for a fast and reliable method for physiological characterisation of fungal strains, a screening approach using a micro titer format was developed...... of the validation, already well described fungal strains were selected and tested using the described method and the developed method was subsequently used to test recombinant fungal strains producing the model polyketide 6-methylsalicylic acid. Diligent application of this strategy significantly reduces the cost...

  11. In situ diagnostic of two-phase flow phenomena in polymer electrolyte fuel cells by neutron imaging

    International Nuclear Information System (INIS)

    Zhang Jianbo; Kramer, Denis; Shimoi, Ryoichi; Ono, Yoshitaka; Lehmann, Eberhard; Wokaun, Alexander; Shinohara, Kazuhiko; Scherer, Guenther G.

    2006-01-01

    The formation of liquid water in operating polymer electrolyte fuel cells (PEFC) of industrial and laboratory size has been investigated by in situ neutron imaging. The influence of the materials chosen for the structural components of the cell on droplet formation and transport in flow fields and on liquid formation in gas diffusion layers has been studied. The changing of the cathodic gas diffusion layer material allowed the relationship between materials, liquid accumulation, and electrochemical performance to be examined. It has been shown that material choice has considerable bearing on the presence of liquid inside the porous structures and the electrochemical characteristics. A simplified quasi one-dimensional cell with an active area of 25 cm 2 was used for materials comparison, and the results were related to technically relevant operating conditions - where inhomogeneities have to be considered - by subsequent examination of cells with an active area of 100 cm 2

  12. Particulate metal bioaccessibility in physiological fluids and cell culture media: Toxicological perspectives.

    Science.gov (United States)

    Leclercq, Bérénice; Alleman, Laurent Yves; Perdrix, Esperanza; Riffault, Véronique; Happillon, Mélanie; Strecker, Alain; Lo-Guidice, Jean-Marc; Garçon, Guillaume; Coddeville, Patrice

    2017-07-01

    According to the literature, tiny amounts of transition metals in airborne fine particles (PM 2.5 ) may induce proinflammatory cell response through reactive oxygen species production. The solubility of particle-bound metals in physiological fluids, i.e. the metal bioaccessibility is driven by factors such as the solution chemical composition, the contact time with the particles, and the solid-to-liquid phase ratio (S/L). In this work, PM 2.5 -bound metal bioaccessibility was assessed in various physiological-like solutions including cell culture media in order to evidence the potential impact on normal human bronchial epithelial cells (NHBE) when studying the cytotoxicity and inflammatory responses of PM 2.5 towards the target bronchial compartment. Different fluids (H 2 O, PBS, LHC-9 culture medium, Gamble and human respiratory mucus collected from COPD patients), various S/L conditions (from 1/6000 to 1/100,000) and exposure times (6, 24 and 72h) were tested on urban PM 2.5 samples. In addition, metals' total, soluble and insoluble fractions from PM 2.5 in LHC-9 were deposited on NHBE cells (BEAS-2B) to measure their cytotoxicity and inflammatory potential (i.e., G6PDH activity, secretion of IL-6 and IL-8). The bioaccessibility is solution-dependent. A higher salinity or organic content may increase or inhibit the bioaccessibiliy according to the element, as observed in the complex mucus matrix. Decreasing the S/L ratio also affect the bioaccessibility depending on the solution tested while the exposure time appears less critical. The LHC-9 culture medium appears to be a good physiological proxy as it induces metal bioaccessibilities close to the mucus values and is little affected by S/L ratios or exposure time. Only the insoluble fraction can be linked to the PM 2.5 -induced cytotoxicity. By contrast, both soluble and insoluble fractions can be related to the secretion of cytokines. The metal bioaccessibility in LHC-9 of the total, soluble, and insoluble

  13. Recreating the Cardiac Microenvironment in Pluripotent Stem Cell Models of Human Physiology and Disease.

    Science.gov (United States)

    Atmanli, Ayhan; Domian, Ibrahim John

    2017-05-01

    The advent of human pluripotent stem cell (hPSC) biology has opened unprecedented opportunities for the use of tissue engineering to generate human cardiac tissue for in vitro study. Engineering cardiac constructs that recapitulate human development and disease requires faithful recreation of the cardiac niche in vitro. Here we discuss recent progress in translating the in vivo cardiac microenvironment into PSC models of the human heart. We review three key physiologic features required to recreate the cardiac niche and facilitate normal cardiac differentiation and maturation: the biochemical, biophysical, and bioelectrical signaling cues. Finally, we discuss key barriers that must be overcome to fulfill the promise of stem cell biology in preclinical applications and ultimately in clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Nerve cell-mimicking liposomes as biosensor for botulinum neurotoxin complete physiological activity.

    Science.gov (United States)

    Weingart, Oliver G; Loessner, Martin J

    2016-12-15

    Botulinum neurotoxins (BoNT) are the most toxic substances known, and their neurotoxic properties and paralysing effects are exploited for medical treatment of a wide spectrum of disorders. To accurately quantify the potency of a pharmaceutical BoNT preparation, its physiological key activities (binding to membrane receptor, translocation, and proteolytic degradation of SNARE proteins) need to be determined. To date, this was only possible using animal models, or, to a limited extent, cell-based assays. We here report a novel in vitro system for BoNT/B analysis, based on nerve-cell mimicking liposomes presenting motoneuronal membrane receptors required for BoNT binding. Following triggered membrane translocation of the toxin's Light Chain, the endopeptidase activity can be quantitatively monitored employing a FRET-based reporter assay within the functionalized liposomes. We were able to detect BoNT/B physiological activity at picomolar concentrations in short time, opening the possibility for future replacement of animal experimentation in pharmaceutical BoNT testing. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Investigation of transport phenomena in HT-PEM-fuel cells; Untersuchung von Transportphaenomenen in der HT-PEM-Brennstoffzelle

    Energy Technology Data Exchange (ETDEWEB)

    Huth, Andreas

    2007-03-26

    High temperature polymer electrolyte fuel cells (HT-PEM-FC) are based on phosphoric acid as the electrolyte and polybenzimidazole as the polymer for the fuel cell membrane. The operating temperature is 160 C. There is little information about this kind of fuel cells in the literature, because the majority of research is done on Nafion {sup registered} fuel cells. The present work uses the electrochemical impedance spectroscopy (EIS) as a tool for the development of HT-PEM-FCs that are resistant to performance losses during the temperature cycle. EIS is used to look inside the fuel cell for investigation of membrane and electrode processes. The proton pump approach is another investigation method. This approach helps to investigate the anode processes and the maximum proton transport capacity. Once the anode processes are allocated in the impedance spectra the other contributions can be found by systematically variation of temperature, cathode gas composition and cathode gas velocity during normal fuel cell operation. The result is an equivalent circuit of the HT-PEM-FC. The frequency-dependent detection of processes enables the user of the EIS-technique to recognise the reason for low power densities or power losses during operation in a temperature cycle. The decrease of the power density of HT-PEM-FCs can be addressed to flooding of the micro gas channels in the catalytic layer of the electrodes. The observed irreversible power loss during temperature cycling of HT-PEM-fuel cells is due to a loss of electrolyte. The solution is a combination of electrolytes as well as a combination of hydroscopic and hydrophobic layers. These MEAs have been tested in a temperature cycle test for more than 800 hours. The result is a performance loss of only 6 %.

  16. Single-Cell Behavior and Population Heterogeneity: Solving an Inverse Problem to Compute the Intrinsic Physiological State Functions

    OpenAIRE

    Spetsieris, Konstantinos; Zygourakis, Kyriacos

    2011-01-01

    The dynamics of isogenic cell populations can be described by cell population balance models that account for phenotypic heterogeneity. To utilize the predictive power of these models, however, we must know the rates of single-cell reaction and division and the bivariate partition probability density function. These three intrinsic physiological state (IPS) functions can be obtained by solving an inverse problem that requires knowledge of the phenotypic distributions for the overall cell popu...

  17. Experimental diagnostics and modeling of inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells

    Science.gov (United States)

    Pivac, Ivan; Šimić, Boris; Barbir, Frano

    2017-10-01

    Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.

  18. Physiologically Based Simulations of Deuterated Glucose for Quantifying Cell Turnover in Humans

    Directory of Open Access Journals (Sweden)

    Christoph Niederalt

    2017-04-01

    Full Text Available In vivo [6,6-2H2]-glucose labeling is a state-of-the-art technique for quantifying cell proliferation and cell disappearance in humans. However, there are discrepancies between estimates of T cell proliferation reported in short (1-day versus long (7-day 2H2-glucose studies and very-long (9-week 2H2O studies. It has been suggested that these discrepancies arise from underestimation of true glucose exposure from intermittent blood sampling in the 1-day study. Label availability in glucose studies is normally approximated by a “square pulse” (Sq pulse. Since the body glucose pool is small and turns over rapidly, the availability of labeled glucose can be subject to large fluctuations and the Sq pulse approximation may be very inaccurate. Here, we model the pharmacokinetics of exogenous labeled glucose using a physiologically based pharmacokinetic (PBPK model to assess the impact of a more complete description of label availability as a function of time on estimates of CD4+ and CD8+ T cell proliferation and disappearance. The model enabled us to predict the exposure to labeled glucose during the fasting and de-labeling phases, to capture the fluctuations of labeled glucose availability caused by the intake of food or high-glucose beverages, and to recalculate the proliferation and death rates of immune cells. The PBPK model was used to reanalyze experimental data from three previously published studies using different labeling protocols. Although using the PBPK enrichment profile decreased the 1-day proliferation estimates by about 4 and 7% for CD4 and CD8+ T cells, respectively, differences with the 7-day and 9-week studies remained significant. We conclude that the approximations underlying the “square pulse” approach—recently suggested as the most plausible hypothesis—only explain a component of the discrepancy in published T cell proliferation rate estimates.

  19. The Biological Role of Nestin(+-Cells in Physiological and Pathological Cardiovascular Remodeling

    Directory of Open Access Journals (Sweden)

    Angelino Calderone

    2018-02-01

    Full Text Available The intermediate filament protein nestin was identified in diverse populations of cells implicated in cardiovascular remodeling. Cardiac resident neural progenitor/stem cells constitutively express nestin and following an ischemic insult migrate to the infarct region and participate in angiogenesis and neurogenesis. A modest number of normal adult ventricular fibroblasts express nestin and the intermediate filament protein is upregulated during the progression of reparative and reactive fibrosis. Nestin depletion attenuates cell cycle re-entry suggesting that increased expression of the intermediate filament protein in ventricular fibroblasts may represent an activated phenotype accelerating the biological impact during fibrosis. Nestin immunoreactivity is absent in normal adult rodent ventricular cardiomyocytes. Following ischemic damage, the intermediate filament protein is induced in a modest population of pre-existing adult ventricular cardiomyocytes bordering the peri-infarct/infarct region and nestin(+-ventricular cardiomyocytes were identified in the infarcted human heart. The appearance of nestin(+-ventricular cardiomyocytes post-myocardial infarction (MI recapitulates an embryonic phenotype and depletion of the intermediate filament protein inhibits cell cycle re-entry. Recruitment of the serine/threonine kinase p38 MAPK secondary to an overt inflammatory response after an ischemic insult may represent a seminal event limiting the appearance of nestin(+-ventricular cardiomyocytes and concomitantly suppressing cell cycle re-entry. Endothelial and vascular smooth muscle cells (VSMCs express nestin and upregulation of the intermediate filament protein may directly contribute to vascular remodeling. This review will highlight the biological role of nestin(+-cells during physiological and pathological remodeling of the heart and vasculature and discuss the phenotypic advantage attributed to the intermediate filament protein.

  20. Evolution and cell physiology. 2. The evolution of cell signaling: from mitochondria to Metazoa.

    Science.gov (United States)

    Blackstone, Neil W

    2013-11-01

    The history of life is a history of levels-of-selection transitions. Each transition requires mechanisms that mediate conflict among the lower-level units. In the origins of multicellular eukaryotes, cell signaling is one such mechanism. The roots of cell signaling, however, may extend to the previous major transition, the origin of eukaryotes. Energy-converting protomitochondria within a larger cell allowed eukaryotes to transcend the surface-to-volume constraints inherent in the design of prokaryotes. At the same time, however, protomitochondria can selfishly allocate energy to their own replication. Metabolic signaling may have mediated this principal conflict in several ways. Variation of the protomitochondria was constrained by stoichiometry and strong metabolic demand (state 3) exerted by the protoeukaryote. Variation among protoeukaryotes was increased by the sexual stage of the life cycle, triggered by weak metabolic demand (state 4), resulting in stochastic allocation of protomitochondria to daughter cells. Coupled with selection, many selfish protomitochondria could thus be removed from the population. Hence, regulation of states 3 and 4, as, for instance, provided by the CO2/soluble adenylyl cyclase/cAMP pathway in mitochondria, was critical for conflict mediation. Subsequently, as multicellular eukaryotes evolved, metabolic signaling pathways employed by eukaryotes to mediate conflict within cells could now be co-opted into conflict mediation between cells. For example, in some fungi, the CO2/soluble adenylyl cyclase/cAMP pathway regulates the transition from yeast to forms with hyphae. In animals, this pathway regulates the maturation of sperm. While the particular features (sperm and hyphae) are distinct, both may involve between-cell conflicts that required mediation.

  1. ATP-sensitive K(+-channels in muscle cells: features and physiological role

    Directory of Open Access Journals (Sweden)

    O. B. Vadzyuk

    2014-08-01

    Full Text Available ATP-sensitive K+-channels of plasma membranes belong to the inward rectifier potassium channels type. They are involved in coupling of electrical activity of muscle cell with its metabolic­ state. These channels are heterooctameric and consist of two types of subunits: four poreforming (Kir 6.х and four regulatory (SUR, sulfonylurea receptor. The Kir subunits contain highly selective K+ filter and provide for high-velocity K+ currents. The SUR subunits contain binding sites for activators and blockers and have metabolic sensor, which enables channel activation under conditions of metabolic stress. ATP blocks K+ currents through the ATP-sensitive K+-channels in the most types of muscle cells. However, functional activity of these channels does not depend on absolute concentration of ATP but on the АТР/ADP ratio and presence of Mg2+. Physiologically active substances, such as phosphatidylinositol bisphosphate and fatty acid esters can regulate the activity of these structures in muscle cells. Activation of these channels under ischemic conditions underlies their cytoprotective action, which results in prevention of Ca2+ overload in cytosol. In contrast to ATP-sensitive K+-channels of plasma membranes, the data regarding the structure and function of ATP-sensitive K+-channels of mitochondrial membrane are contradictory. Pore-forming subunits of this channel have not been firmly identified yet. ATP-sensitive K+ transport through the mitochondrial­ membrane is easily tested by different methods, which are briefly reviewed in this paper. Interaction of mitoKATP with physiological and pharmacological ligands is discussed as well.

  2. Physiological problems in patients undergoing autologous and allogeneic hematopoietic stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Sevgisun Kapucu

    2014-01-01

    Full Text Available Objective: Stem cell transplantation is usually performed in an effort to extend the patient′s life span and to improve their quality of life. This study was conducted to determine the postoperative physiological effects experienced by patients who had undergone autologous and allogeneic stem cell transplantation. Methods: The research is a descriptive study conducted with a sample of 60 patients at Stem Cell Transplantation Units in Ankara. Percentile calculation and chi-square tests were used to evaluate the data. Results: When a comparison was made between patients who had undergone allogeneic Hematopoietic stem cell transplantation (HSCT and those who had undergone autologous HSCT, results indicated that problems occurred more often for the allogeneic HSCT patients. The problems included: Digestion (94.3%, dermatological (76.7%, cardiac and respiratory (66.7%, neurological (66.7%, eye (56.7%, infections (26.7% and Graft Versus Host Disease (5 patients. Furthermore, the problems with pain (50%, numbness and tingling (40%, and speech disorders (3 patients were observed more often in autologous BMT patients. Conclusion: Autologous and allogeneic patients experienced most of physical problems due to they receive high doses of chemotherapy. Therefore, it is recommended that an interdisciplinary support team approach should be usedtohelp reduce and manage the problems that may arise during patient care.

  3. Impact of sodium butyrate and mild hypothermia on metabolic and physiological behaviour of CHO TF 70R cells

    Directory of Open Access Journals (Sweden)

    Veronica Avello

    2017-05-01

    Conclusions: The combination of NaBu addition and mild hypothermic condition causes an impact on physiological and metabolic state of CHO TF 70R cells, decreasing cell growth rate and improving glucose consumption efficiency. These results therefore provide a promising strategy to increase specific productivity of rh-tPA.

  4. Physiologic time: A hypothesis

    Science.gov (United States)

    West, Damien; West, Bruce J.

    2013-06-01

    The scaling of respiratory metabolism with body size in animals is considered by many to be a fundamental law of nature. One apparent consequence of this law is the scaling of physiologic time with body size, implying that physiologic time is separate and distinct from clock time. Physiologic time is manifest in allometry relations for lifespans, cardiac cycles, blood volume circulation, respiratory cycle, along with a number of other physiologic phenomena. Herein we present a theory of physiologic time that explains the allometry relation between time and total body mass averages as entailed by the hypothesis that the fluctuations in the total body mass are described by a scaling probability density.

  5. Extra-anatomic transplantations in autologous adult cell therapies aiding anatomical regeneration and physiological recovery – An insight and categorization

    Directory of Open Access Journals (Sweden)

    Editorial

    2015-12-01

    cells (source originate from the ectoderm while the epithelial lining of the urethra (target arises from the endoderm and the process of dysfunctional cell replacement occurs within the target. Gingival fibroblasts originate from the neural crest (source while dermal fibroblasts are derived from mesoderm (target and the process that follows is again replacement of dysfunctional cells. These, we propose, should be termed as “Trans-germ Extra-anatomic Cell Therapy” (TECT. In both IECT and TECT the transplantation is extra-anatomic and the presently known mechanism of the transplanted cells in helping with the regeneration are different, however, the transplanted cells aid directly or indirectly with the anatomical regeneration and/or physiological recovery of the target tissue and thereby the organ. While it is to be noted that he mechanisms of such repair by these adult autologous cells in different applications vary from direct replacement of cells to aiding in repair by paracrine effect or secretion of growth factors and that the extent of such repair or regeneration too has significant variations, the significance of this categorization in future clinical therapy are worth a thorough investigation and evaluation and how we can harness the potential of this extraordinary transdifferentiation process for clinical benefits. Extra-anatomic transplantations of in vitro expanded mature adult cells, without any genetic manipulation or in vitro trans-differentiation, have yielded dramatic anatomical regeneration of the host tissues as well as physiological recovery. The fine details describing the transformation process between guest cells and the host tissues are incomplete. The principles underpinning this phenomena must be established to fully exploit its potential as a clinical therapy with broad application. The composition of the cell mass used as a source for transplantation therapy, in terms of stem cells, precursor cells and mature adult cells, as well as

  6. Immune phenomena in echinoderms.

    Science.gov (United States)

    Gliński, Z; Jarosz, J

    2000-01-01

    Advances in biochemistry and molecular biology have made it possible to identify a number of mechanisms active in the immune phenomena of echinoderms. It is obvious that echinoderms have the ability to distinguish between different foreign objects (pathologically changed tissues, microorganisms, parasites, grafts) and to express variable effector mechanisms which are elicited specifically and repeatably after a variety of non-self challenges. The molecular and biochemical basis for the expression of these variable defense mechanisms and the specific signals which elicit one type of effector mechanism are not, however, yet well known. The high capacity of coelomocytes to phagocytose, entrap and encapsulate invading microorganisms is a valid immune cell-mediated mechanism of echinoderms. The entrapped bacteria, discharged cellular materials and disintegrating granular cells are compacted and provoke the cellular encapsulation reaction. Moreover, humoral-based reactions form an integral part of the echinoderm defense system against microbial invaders. Factors such as lysozyme, perforins (hemolysins) vitellogenin and lectins are normal constituents of hemolymph, while cytokines are synthesized by echinoderms in response to infection.

  7. A simple method for the investigation of cell separation effects of blood with physiological hematocrit values.

    Science.gov (United States)

    Gester, Kathrin; Jansen, Sebastian V; Stahl, Marion; Steinseifer, Ulrich

    2015-05-01

    Even though the separation of blood into erythrocyte-rich and erythrocyte-poor areas is well known in physiological setups such as small vessels, it has recently come into focus in small gaps in cardiovascular applications. Studies show that separation effects occur, for example, in gaps in hydrodynamic bearings, where they can have a positive effect on hemolysis. Separation effects depend on the hematocrit value, but due to visualization issues, studies in small gaps used very low hematocrit values. In this study, a test setup and an evaluation method for the investigation of separation effects of blood with hematocrit values of 30, 45, and 60% were developed. The erythrocyte distribution was evaluated by means of gray scale value distribution. This principle is based on the fact that an erythrocyte-rich region is more opaque than an erythrocyte-poor region. The experimental setup is designed in a way that no further processes (e.g., fluorescence labeling) need to be carried out which might change the properties of the membrane of the erythrocytes, and therefore their flow properties. Additionally, the method is executable with basic laboratory equipment, which makes it applicable for many laboratories. To validate the feasibility of the method, the influence of the diameter and the flow rate on the migration of erythrocytes were studied in micro channels for three different physiological hematocrit values. Even though no individual cells were traced, plasma layer and areas of high erythrocyte concentration could be identified. Dependencies of the erythrocyte distribution on flow rate and channel diameter were validated. The influence of the hematocrit value was demonstrated as well and showed the hematocrit value to be a crucial factor when investigating cell separation. The experimental results were consistent with findings in the literature. As the developed method is suitable for physiological hematocrit values and easy to handle, it provides an optimal basis

  8. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    International Nuclear Information System (INIS)

    Sheard, Michael A.; Ghent, Matthew V.; Cabral, Daniel J.; Lee, Joanne C.; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q.; Kang, Min H.

    2015-01-01

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent

  9. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    Energy Technology Data Exchange (ETDEWEB)

    Sheard, Michael A., E-mail: msheard@chla.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ghent, Matthew V., E-mail: mattghent@gmail.com [Department of Pathology, Keck School of Medicine, University of Southern California, Health Sciences Campus, Los Angeles, CA 90089 (United States); Cabral, Daniel J., E-mail: dcabral14@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Lee, Joanne C., E-mail: joannebarnhart@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Khankaldyyan, Vazgen, E-mail: khangaldian@yahoo.com [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ji, Lingyun, E-mail: lingyun.ji@med.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Wu, Samuel Q., E-mail: swu@chla.usc.edu [Medical Genetics, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Kang, Min H., E-mail: min.kang@ttuhsc.edu [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); and others

    2015-05-15

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.

  10. Artificial fish skin of self-powered micro-electromechanical systems hair cells for sensing hydrodynamic flow phenomena

    Science.gov (United States)

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Miao, Jianmin; Warkiani, Majid Ebrahimi; Triantafyllou, Michael S.

    2015-01-01

    Using biological sensors, aquatic animals like fishes are capable of performing impressive behaviours such as super-manoeuvrability, hydrodynamic flow ‘vision’ and object localization with a success unmatched by human-engineered technologies. Inspired by the multiple functionalities of the ubiquitous lateral-line sensors of fishes, we developed flexible and surface-mountable arrays of micro-electromechanical systems (MEMS) artificial hair cell flow sensors. This paper reports the development of the MEMS artificial versions of superficial and canal neuromasts and experimental characterization of their unique flow-sensing roles. Our MEMS flow sensors feature a stereolithographically fabricated polymer hair cell mounted on Pb(Zr0.52Ti0.48)O3 micro-diaphragm with floating bottom electrode. Canal-inspired versions are developed by mounting a polymer canal with pores that guide external flows to the hair cells embedded in the canal. Experimental results conducted employing our MEMS artificial superficial neuromasts (SNs) demonstrated a high sensitivity and very low threshold detection limit of 22 mV/(mm s−1) and 8.2 µm s−1, respectively, for an oscillating dipole stimulus vibrating at 35 Hz. Flexible arrays of such superficial sensors were demonstrated to localize an underwater dipole stimulus. Comparative experimental studies revealed a high-pass filtering nature of the canal encapsulated sensors with a cut-off frequency of 10 Hz and a flat frequency response of artificial SNs. Flexible arrays of self-powered, miniaturized, light-weight, low-cost and robust artificial lateral-line systems could enhance the capabilities of underwater vehicles. PMID:26423435

  11. Design of all-optical memory cell using EIT and lasing without inversion phenomena in optical micro ring resonators

    Science.gov (United States)

    Pasyar, N.; Yadipour, R.; Baghban, H.

    2017-07-01

    The proposed design of the optical memory unit cell contains dual micro ring resonators in which the effect of lasing without inversion (LWI) in three-level nano particles doped over the optical resonators or integrators as the gain segment is used for loss compensation. Also, an on/off phase shifter based on electromagnetically induced transparency (EIT) in three-level quantum dots (QDs) has been used for data reading at requested time. Device minimizing for integrated purposes and high speed data storage are the main advantages of the optical integrator based memory.

  12. [Paraneoplastic phenomena in patients with a thymoma].

    Science.gov (United States)

    Strijbos, Ellen; Pomp, Jacqueline; Gilhuis, H Jacobus

    2013-01-01

    A thymoma arises from the epithelial cells of the thymus. Local tumour growth may cause symptoms like coughing, dyspnoea or chest pain. Paraneoplastic phenomena can also occur in patients with a thymoma; myasthenia gravis is a well-known example. Other neurological, dermatological, cardiological and haematological disorders are not always recognised as being paraneoplastic phenomena. There is no clear relationship between tumour activity and the clinical course of paraneoplastic phenomena. The three cases in this article illustrate how the clinical presentation of these phenomena can vary.

  13. Physiological Role of TNF in MucosalImmunology: Regulation of Macrophage/Dendritic Cell Function

    DEFF Research Database (Denmark)

    Rivollier, Aymeric Marie Christian; Marsal, J.; Agace, William Winston

    2015-01-01

    to the pathogenesis of inflammatory bowel disease. In this review, we discuss the role of tumor necrosis factor-α (TNF) in regulating multiple aspects of intestinal Mϕ and DC physiology, including their differentiation, migration, maturation, survival and effector functions. In inflammatory bowel disease, TNF...... signaling has been implicated in reprogramming monocyte differentiation from the anti-inflammatory Mϕ lineage towards the pro-inflammatory mononuclear phagocyte lineage.These cells become a major source of TNF and, thus,may contribute to the chronic inflammatory process. Finally,we highlight some...... of the important gaps in our current knowledge regarding the role of TNF in Mϕ and DCphysiology and suggest important directions for future research in this field....

  14. Modeling coupled transport and electrochemical reaction phenomena in polymer electrolyte fuel cell electrode by Lattice Boltzmann method

    Science.gov (United States)

    Tarokh, Atefeh; Tarokh, Ali; Hejazi, Hossein; Karan, Kunal

    2015-11-01

    Fuel cells convert chemical energy of a fuel directly into electricity. The overall process is a result of coupled reaction-transport processes. The electrochemical reactions occur in porous composite catalysts layers with intermingled material phases, often made up of nano-sized particles and nano/micrometers pores. In a polymer electrolye fuel cell (PEFC) catalyst layer, the focus of this work, transport of electrons through carbon, transport of protons through ion-conducting polymer (ionomer), diffusion of gases through pores must be considered. The three different reacting species, viz. protons, electrons and reactive molecule (H2 or O2) must co-exist at the reactive interface formed by Pt catalyst surface covered by an ionomer film. We use Lattice Boltzmann Method to capture the interactions between chemistry, transport and porous medium geometries in a PEFC catalyst layer. We report the simulation results for a model but novel catalyst architecture made of a continuous carbon phase with organized pore structure. The Pt catalyst is dispersed on the internal surface of the carbon. This Pt-catalyst decorated surface is covered by a thin ionomer film. In particular, we are interested in explicitly capturing the complexity of the pore geometry and Knudsen diffusion effects.

  15. Two-sided effect of Cordyceps sinensis on dendritic cells in different physiological stages.

    Science.gov (United States)

    Li, Chia-Yang; Chiang, Chi-Shiun; Tsai, Min-Lung; Hseu, Ruey-Shyang; Shu, Wun-Yi; Chuang, Chun-Yu; Sun, Yuh-Chang; Chang, Yuan-Shiun; Lin, Jaung-Geng; Chen, Chih-Sheng; Huang, Ching-Lung; Hsu, Ian C

    2009-06-01

    Cordyceps sinensis (CS), a Chinese tonifying herb, has been widely used for centuries in Asian countries as a medicine and a health supplement. Although ample evidence indicates that CS can modulate immune responses, the functional effect of CS on dendritic cells (DCs) is still unclear. This study examines how CS affects human monocyte-derived DCs in two physiological states: naïve and LPS-induced inflammatory. Our experimental results demonstrate that CS acts as an activator and maturation inducer of immature DCs by stimulating the expression of costimulatory molecules and proinflammatory cytokines by DCs, enhancing the DC-induced, allogeneic T cell proliferation, and reducing the endocytic ability of DCs. In contrast, CS suppresses the LPS-induced, inflammatory response by decreasing the LPS-induced expression of costimulatory molecules and proinflammatory cytokines by DCs. CS also suppresses the LPS-induced, DC-elicited, allogeneic T cell proliferation and shifts the LPS-activated, DC-driven Th1 response toward a Th2 response. These results demonstrate that CS differentially regulates the DC activities according to the presence or absence of the inflammatory signs. Restated, with the lack of an ongoing inflammatory environment, CS primes DCs toward a Th1-type immunity, whereas in a potential inflammatory reaction, CS balances the over-reactivity of elicited Th1 immunity. This investigation illustrates the Yin-Yang balancing effects of CS as a medicine and a health supplement.

  16. Role of Stro1+/CD44+ stem cells in myometrial physiology and uterine remodeling during pregnancy.

    Science.gov (United States)

    Mas, Aymara; Prusinski, Lauren; Yang, Qiwei; Diaz-Gimeno, Patricia; Stone, Lelyand; Diamond, Michael P; Simón, Carlos; Al-Hendy, Ayman

    2017-01-01

    Regulation of myometrial functions during pregnancy has been considered the result of the integration of endocrine and mechanical signals. Nevertheless, uterine regeneration is poorly understood, and the cellular source within the gravid uterus is largely unexplored.In this study, we isolated and quantified the myometrial stem cells (MSC) population from pregnant female Eker rat uteri, by using Stro1/CD44 surface markers. We demonstrated that prior parity significantly increased the percentage of Stro1+/CD44+ MSC because of injured tissue response. Interestingly, we established that Stro1+/CD44+ MSC respond efficiently to physiological cues when they were treated in vitro under different dose-dependent pregnant rat serum.Previous studies reveal strong regulatory links between O2 availability and stem cell function. Based on these premises, cell proliferation assays showed that isolated Stro1+/CD44+ MSC possess a higher proliferative rate under hypoxic versus normoxic conditions. We also detected a total of 37 upregulated and 44 downregulated hypoxia-related genes, which were differentially expressed in Stro1+/CD44+ MSC, providing an alternative approach to infer into complex molecular mechanisms such as energy metabolism, inflammatory response, uterine expansion, and/or remodeling.Since these cells preferentially grow under low oxygen conditions, we propose that the increase of the rat uterus during pregnancy involves myometrial oxygen consumption, thereby enhancing MSC proliferation. Moreover, pregnancy-induced mechanical stretching results in hypoxic conditions, ultimately creating an environment that promotes stem cell proliferation and further uterine enlargement, which is essential for a successful pregnancy. In summary, all of these data support that rat Stro1+/CD44+ MSC contribute to uterine enlargement during pregnancy. © The Author 2016. Published by Oxford University Press on behalf of Society for the Study of Reproduction.

  17. LABILE IRON IN CELLS AND BODY FLUIDS . Physiology, Pathology and Pharmacology

    Directory of Open Access Journals (Sweden)

    Zvi Ioav Cabantchik

    2014-03-01

    Full Text Available In living systems iron appears predominantly associated with proteins, but can also be detected in forms referred as labile iron, which denotes the combined redox properties of iron and its amenability to exchange between ligands, including chelators. The labile cell iron (LCI composition varies with metal concentration and substances with chelating groups but also with pH and the redox potential. Although physiologically in the lower µM range, LCI plays a key role in cell iron economy as cross-roads of metabolic pathways. LCI levels are continually regulated by an iron-responsive machinery that balances iron uptake versus deposition into ferritin. However, LCI rises aberrantly in some cell types due to faulty cell utilization pathways or infiltration by pathological iron forms that are found in hemosiderotic plasma. As LCI attains pathological levels, it can catalyze reactive O species (ROS formation that, at particular threshold, can surpass cellular anti-oxidant capacities and seriously damage its constituents. While in normal plasma and interstitial fluids, virtually all iron is securely carried by circulating transferrin (that renders iron essentially non-labile, in systemic iron overload (IO, the total plasma iron binding capacity is often surpassed by a massive iron influx from hyperabsorptive gut or from erythrocyte overburdened spleen and/or liver. As plasma transferrin approaches iron saturation, labile plasma iron (LPI emerges in forms that can infiltrate cells by unregulated routes and raise LCI to toxic levels. Despite the limited knowledge available on LPI speciation in different types and degrees of iron overload, LPI measurements can be and are in fact used for identifying systemic IO and for initiating/adjusting chelation regimens to attain full-day LPI protection. A recent application of labile iron assay is the detection of labile components in iv iron formulations per se as well as in plasma (LPI following parenteral iron

  18. Thrombospondin-1, -2 and -5 have differential effects on vascular smooth muscle cell physiology

    Energy Technology Data Exchange (ETDEWEB)

    Helkin, Alex; Maier, Kristopher G. [SUNY Upstate Medical University, Division of Vascular Surgery and Endovascular Services, Syracuse, NY (United States); Department of Veterans Affairs VA Healthcare Network Upstate New York at Syracuse, Syracuse, NY (United States); Gahtan, Vivian, E-mail: gahtanv@upstate.edu [SUNY Upstate Medical University, Division of Vascular Surgery and Endovascular Services, Syracuse, NY (United States); Department of Veterans Affairs VA Healthcare Network Upstate New York at Syracuse, Syracuse, NY (United States)

    2015-09-04

    Introduction: The thrombospondins (TSPs) are matricellular proteins that exert multifunctional effects by binding cytokines, cell-surface receptors and other proteins. TSPs play important roles in vascular pathobiology and are all expressed in arterial lesions. The differential effects of TSP-1, -2, and -5 represent a gap in knowledge in vascular smooth muscle cell (VSMC) physiology. Our objective is to determine if structural differences of the TSPs imparted different effects on VSMC functions critical to the formation of neointimal hyperplasia. We hypothesize that TSP-1 and -2 induce similar patterns of migration, proliferation and gene expression, while the effects of TSP-5 are different. Methods: Human aortic VSMC chemotaxis was tested for TSP-2 and TSP-5 (1–40 μg/mL), and compared to TSP-1 and serum-free media (SFM) using a modified Boyden chamber. Next, VSMCs were exposed to TSP-1, TSP-2 or TSP-5 (0.2–40 μg/mL). Proliferation was assessed by MTS assay. Finally, VSMCs were exposed to TSP-1, TSP-2, TSP-5 or SFM for 3, 6 or 24 h. Quantitative real-time PCR was performed on 96 genes using a microfluidic card. Statistical analysis was performed by ANOVA or t-test, with p < 0.05 being significant. Results: TSP-1, TSP-2 and TSP-5 at 20 μg/mL all induce chemotaxis 3.1 fold compared to serum-free media. TSP-1 and TSP-2 induced proliferation 53% and 54% respectively, whereas TSP-5 did not. In the gene analysis, overall, cardiovascular system development and function is the canonical pathway most influenced by TSP treatment, and includes multiple growth factors, cytokines and proteases implicated in cellular migration, proliferation, vasculogenesis, apoptosis and inflammation pathways. Conclusions and relevance: The results of this study indicate TSP-1, -2, and -5 play active roles in VSMC physiology and gene expression. Similarly to TSP-1, VSMC chemotaxis to TSP-2 and -5 is dose-dependent. TSP-1 and -2 induces VSMC proliferation, but TSP-5 does not, likely

  19. Hydrazine selective dual signaling chemodosimetric probe in physiological conditions and its application in live cells

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Sandip; Sahana, Animesh; Mandal, Sandip [Department of Chemistry, The University of Burdwan, Burdwan, 713104 West Bengal (India); Sengupta, Archya; Chatterjee, Ansuman [Department of Zoology, Visva Bharati University, Santiniketan, West Bengal (India); Safin, Damir A., E-mail: damir.a.safin@gmail.com [Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium); Babashkina, Maria G.; Tumanov, Nikolay A.; Filinchuk, Yaroslav [Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium); Das, Debasis, E-mail: ddas100in@yahoo.com [Department of Chemistry, The University of Burdwan, Burdwan, 713104 West Bengal (India)

    2015-09-17

    A rhodamine–cyanobenzene conjugate, (E)-4-((2-(3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthene] -2-yl)ethylimino)methyl)benzonitrile (1), which structure has been elucidated by single crystal X-ray diffraction, was synthesized for selective fluorescent “turn-on” and colorimetric recognition of hydrazine at physiological pH 7.4. It was established that 1 detects hydrazine up to 58 nM. The probe is useful for the detection of intracellular hydrazine in the human breast cancer cells MCF-7 using a fluorescence microscope. Spirolactam ring opening of 1, followed by its hydrolysis, was established as a probable mechanism for the selective sensing of hydrazine. - Highlights: • A selective rhodamine–cyanobenzene conjugate is synthesized. • The conjugate is a selective dual signaling chemodosimetric probe towards hydrazine. • Spirolactam ring opening of the probe, followed by its hydrolysis, is the sensing mechanism. • The probe detects hydrazine in the human breast cancer cells MCF-7 imaging.

  20. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  1. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E

    1991-01-01

    In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are

  2. Science and Paranormal Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Noyes, H. Pierre

    1999-06-03

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.

  3. Blood Outgrowth Endothelial Cells Increase Tumor Growth Rates and Modify Tumor Physiology: Relevance for Therapeutic Targeting

    International Nuclear Information System (INIS)

    Pagan, Jonathan; Przybyla, Beata; Jamshidi-Parsian, Azemat; Gupta, Kalpna; Griffin, Robert J.

    2013-01-01

    Endothelial cell precursors from human peripheral blood have been shown to home to areas of neovascularization and may assist tumor growth by increasing or fortifying blood vessel growth. In the present study, the influence of these cells on tumor growth and physiology was investigated and the role of these cells as a therapeutic target or in determining treatment sensitivity was tested. After isolation from human blood and expansion in vitro, actively growing cells with verified endothelial phenotype (Blood Outgrowth Endothelial Cell, BOEC) were injected i.v. into tumor bearing mice for three consecutive days. The growth rate was significantly enhanced in relatively small RERF human lung tumors (i.e., less than 150 mm 3 ) grown in immunocompromised mice by an average of 1.5-fold while it had no effect when injections were given to animals bearing larger tumors. There were no signs of toxicity or unwanted systemic effects. We also observed evidence of increased perfusion, vessel number, response to 15 Gy radiation and oxygenation in RERF tumors of animals injected with BOECs compared to control tumors. In addition, FSaII murine fibrosarcoma tumors were found to grow faster upon injection of BOECs. When FSaII tumors were subjected to a partial thermal ablation treatment using high intensity focused ultrasound (HIFU) there was consistently elevated detection of fluorescently labeled and i.v. injected endothelial precursors in the tumor when analyzed with optical imaging and/or histological preparations. Importantly, we also observed that BOECs treated with the novel anti-angiogenic peptide anginex in-vitro, show decreased proliferation and increased sensitivity to radiation. In vivo, the normal increase in FSaII tumor growth induced by injected BOECs was blunted by the addition of anginex treatment. It appears that endothelial precursors may significantly contribute to tumor vessel growth, tumor progression and/or repair of tumor damage and may improve the

  4. A laccase-glucose oxidase biofuel cell prototype operating in a physiological buffer

    Energy Technology Data Exchange (ETDEWEB)

    Barriere, Frederic [Universite de Rennes I, Institut de Chimie, UMR CNRS 6510, 35042 Rennes (France); Kavanagh, Paul; Leech, Donal [Department of Chemistry, National University of Ireland, Galway (Ireland)

    2006-07-15

    Here we report on the design and study of a biofuel cell consisting of a glucose oxidase-based anode (Aspergillus niger) and a laccase-based cathode (Trametes versicolor) using osmium-based redox polymers as mediators of the biocatalysts' electron transfer at graphite electrode surfaces. The graphite electrodes of the device are modified with the deposition and immobilization of the appropriate enzyme and the osmium redox polymer mediator. A redox polymer [Os(4,4'-diamino-2,2'bipyridine){sub 2}(poly(N-vinylimidazole))-(poly(N-vinylimidazole)){sub 9}Cl]Cl (E{sup 0}'=-0.110V versus Ag/AgCl) of moderately low redox potential is used for the glucose oxidizing anode and a redox polymer [Os(phenanthroline){sub 2}(poly(N-vinylimidazole)){sub 2}-(poly(N-vinylimidazole)){sub 8}]Cl {sub 2} (E{sup 0}'=0.49V versus Ag/AgCl) of moderately high redox potential is used at the dioxygen reducing cathode. The enzyme and redox polymer are cross-linked with polyoxyethylene bis(glycidyl ether). The working biofuel cell was studied under air at 37{sup o}C in a 0.1M phosphate buffer solution of pH range 4.4-7.4, containing 0.1M sodium chloride and 10mM glucose. Under physiological conditions (pH 7.4) maximum power density, evaluated from the geometric area of the electrode, reached 16{mu}W/cm{sup 2} at a cell voltage of 0.25V. At lower pH values maximum power density was 40{mu}W/cm{sup 2} at 0.4V (pH 5.5) and 10{mu}W/cm{sup 2} at 0.3V (pH 4.4). (author)

  5. Gene expression profiling of dendritic cells in different physiological stages under Cordyceps sinensis treatment.

    Directory of Open Access Journals (Sweden)

    Chia-Yang Li

    Full Text Available Cordyceps sinensis (CS has been commonly used as herbal medicine and a health supplement in China for over two thousand years. Although previous studies have demonstrated that CS has benefits in immunoregulation and anti-inflammation, the precise mechanism by which CS affects immunomodulation is still unclear. In this study, we exploited duplicate sets of loop-design microarray experiments to examine two different batches of CS and analyze the effects of CS on dendritic cells (DCs, in different physiology stages: naïve stage and inflammatory stage. Immature DCs were treated with CS, lipopolysaccharide (LPS, or LPS plus CS (LPS/CS for two days, and the gene expression profiles were examined using cDNA microarrays. The results of two loop-design microarray experiments showed good intersection rates. The expression level of common genes found in both loop-design microarray experiments was consistent, and the correlation coefficients (Rs, were higher than 0.96. Through intersection analysis of microarray results, we identified 295 intersecting significantly differentially expressed (SDE genes of the three different treatments (CS, LPS, and LPS/CS, which participated mainly in the adjustment of immune response and the regulation of cell proliferation and death. Genes regulated uniquely by CS treatment were significantly involved in the regulation of focal adhesion pathway, ECM-receptor interaction pathway, and hematopoietic cell lineage pathway. Unique LPS regulated genes were significantly involved in the regulation of Toll-like receptor signaling pathway, systemic lupus erythematosus pathway, and complement and coagulation cascades pathway. Unique LPS/CS regulated genes were significantly involved in the regulation of oxidative phosphorylation pathway. These results could provide useful information in further study of the pharmacological mechanisms of CS. This study also demonstrates that with a rigorous experimental design, the biological effects

  6. Gene expression profiling of dendritic cells in different physiological stages under Cordyceps sinensis treatment.

    Science.gov (United States)

    Li, Chia-Yang; Chiang, Chi-Shiun; Cheng, Wei-Chung; Wang, Shu-Chi; Cheng, Hung-Tsu; Chen, Chaang-Ray; Shu, Wun-Yi; Tsai, Min-Lung; Hseu, Ruey-Shyang; Chang, Cheng-Wei; Huang, Chao-Ying; Fang, Shih-Hua; Hsu, Ian C

    2012-01-01

    Cordyceps sinensis (CS) has been commonly used as herbal medicine and a health supplement in China for over two thousand years. Although previous studies have demonstrated that CS has benefits in immunoregulation and anti-inflammation, the precise mechanism by which CS affects immunomodulation is still unclear. In this study, we exploited duplicate sets of loop-design microarray experiments to examine two different batches of CS and analyze the effects of CS on dendritic cells (DCs), in different physiology stages: naïve stage and inflammatory stage. Immature DCs were treated with CS, lipopolysaccharide (LPS), or LPS plus CS (LPS/CS) for two days, and the gene expression profiles were examined using cDNA microarrays. The results of two loop-design microarray experiments showed good intersection rates. The expression level of common genes found in both loop-design microarray experiments was consistent, and the correlation coefficients (Rs), were higher than 0.96. Through intersection analysis of microarray results, we identified 295 intersecting significantly differentially expressed (SDE) genes of the three different treatments (CS, LPS, and LPS/CS), which participated mainly in the adjustment of immune response and the regulation of cell proliferation and death. Genes regulated uniquely by CS treatment were significantly involved in the regulation of focal adhesion pathway, ECM-receptor interaction pathway, and hematopoietic cell lineage pathway. Unique LPS regulated genes were significantly involved in the regulation of Toll-like receptor signaling pathway, systemic lupus erythematosus pathway, and complement and coagulation cascades pathway. Unique LPS/CS regulated genes were significantly involved in the regulation of oxidative phosphorylation pathway. These results could provide useful information in further study of the pharmacological mechanisms of CS. This study also demonstrates that with a rigorous experimental design, the biological effects of a complex

  7. A laccase-glucose oxidase biofuel cell prototype operating in a physiological buffer

    International Nuclear Information System (INIS)

    Barriere, Frederic; Kavanagh, Paul; Leech, Donal

    2006-01-01

    Here we report on the design and study of a biofuel cell consisting of a glucose oxidase-based anode (Aspergillus niger) and a laccase-based cathode (Trametes versicolor) using osmium-based redox polymers as mediators of the biocatalysts' electron transfer at graphite electrode surfaces. The graphite electrodes of the device are modified with the deposition and immobilization of the appropriate enzyme and the osmium redox polymer mediator. A redox polymer [Os(4,4'-diamino-2,2'bipyridine) 2 (poly{N-vinylimidazole})-(poly{ N-vinylimidazole}) 9 Cl]Cl (E ' = -0.110 V versus Ag/AgCl) of moderately low redox potential is used for the glucose oxidizing anode and a redox polymer [Os(phenanthroline) 2 (poly{N-vinylimidazole}) 2 -(poly{N-vinylimidazole}) 8 ]Cl 2 (E ' = 0.49 V versus Ag/AgCl) of moderately high redox potential is used at the dioxygen reducing cathode. The enzyme and redox polymer are cross-linked with polyoxyethylene bis(glycidyl ether). The working biofuel cell was studied under air at 37 deg. C in a 0.1 M phosphate buffer solution of pH range 4.4-7.4, containing 0.1 M sodium chloride and 10 mM glucose. Under physiological conditions (pH 7.4) maximum power density, evaluated from the geometric area of the electrode, reached 16 μW/cm 2 at a cell voltage of 0.25 V. At lower pH values maximum power density was 40 μW/cm 2 at 0.4 V (pH 5.5) and 10 μW/cm 2 at 0.3 V (pH 4.4)

  8. Consequences of calorie restriction and calorie excess for the physiological parameters of the yeast Saccharomyces cerevisiae cells.

    Science.gov (United States)

    Maslanka, Roman; Kwolek-Mirek, Magdalena; Zadrag-Tecza, Renata

    2017-12-01

    Glucose plays an important role in cell metabolism and has an impact on cellular physiology. Changes in glucose availability may strongly influence growth rate of the cell size, cell metabolism and the rate of generation of cellular by-products, such as reactive oxygen species. The positive effect of low glucose concentration conditions-calorie restriction is observed in a wide range of species, including the Saccharomyces cerevisiae yeast, yet little is known about the effect of high glucose concentrations-calorie excess. Such analysis seems to be particularly important due to recently common problem of diabetes and obesity. The effect of glucose on morphological and physiological parameters of the yeast cell was conducted using genetic alteration (disruption of genes involved in glucose signalling) and calorie restriction and calorie excess conditions. The results show a significant relationship among extracellular glucose concentration, cell size and reactive oxygen species generation in yeast cells. Furthermore, the results obtained through the use of mutant strains with disorders in glucose signalling pathways suggest that the intracellular level of glucose is more important than its extracellular concentration. These data also suggest that the calorie excess as a factor, which has a significant impact on cell physiology, requires further comprehensive analyses. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Interfacial transport phenomena

    CERN Document Server

    Slattery, John C; Oh, Eun-Suok

    2007-01-01

    Revised and updated extensively from the previous editionDiscusses transport phenomena at common lines or three-phase lines of contactProvides a comprehensive summary about the extensions of continuum mechanics to the nanoscale.

  10. Severe accident phenomena

    International Nuclear Information System (INIS)

    Jokiniemi, J.; Kilpi, K.; Lindholm, I.; Maekynen, J.; Pekkarinen, E.; Sairanen, R.; Silde, A.

    1995-02-01

    Severe accidents are nuclear reactor accidents in which the reactor core is substantially damaged. The report describes severe reactor accident phenomena and their significance for the safety of nuclear power plants. A comprehensive set of phenomena ranging from accident initiation to containment behaviour and containment integrity questions are covered. The report is based on expertise gained in the severe accident assessment projects conducted at the Technical Research Centre of Finland (VTT). (49 refs., 32 figs., 12 tabs.)

  11. Integration phenomena Paralympic cyclists

    OpenAIRE

    Diepoldová, Tereza

    2017-01-01

    Title: Integration phenomena Paralympic cyclists. Objectives of work: Try to find integration phenomena in relation to sport training and its impact on selected cyclists with disabilities. Methods: Case report structured interview, data collection method - the method of interrogation. Results: Based on case studies developed a structured interview, we found differences in the integration, which we have divided into phases - before obtaining disability, acclimatization, sports integration. Fur...

  12. Modelling of Transport Phenomena

    OpenAIRE

    K., Itoh; S.-I., Itoh; A., Fukuyama

    1993-01-01

    In this review article, we discuss key features of the transport phenomena and theoretical modelling to understand them. Experimental observations have revealed the nature of anomalous transport, i.e., the enhancement of the transport coefficients by the gradients of the plasma profiles, the pinch phenomena, the radial profile of the apomalous transport coefficients, the variation of the transport among the Bohm diffusion, Pseudo-classical confinement, L-mode and variety of improved confineme...

  13. Fundamentals of Fire Phenomena

    DEFF Research Database (Denmark)

    Quintiere, James

    analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... as a visiting professor at BYG.DTU financed by the Larsen and Nielsen Foundation, and is entered to the research database by Kristian Hertz responsible for the visiting professorship....

  14. Flavor formation and cell physiology during the production of alcohol-free beer with immobilized Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Iersel, van M.F.M.; Dieren, van B.; Rombouts, F.M.; Abee, T.

    1999-01-01

    Production of alcohol-free beer by limited fermentation is optimally performed in a packed-bed reactor operating in downflow. This ensures a highly controllable system with optimal reactor design. In the present study, we report on changes in the physiology of immobilized yeast cells in the reactor.

  15. A prototype electronic board to investigate galvanotaxis phenomena

    Science.gov (United States)

    Zironi, I.; Boccioletti, L.; Amorini, F.; Castellani, G.; Gabrielli, A.

    2017-05-01

    Galvanotaxis is a bioelectronic phenomenon described since the end of the 19th century, that indicates the movement of a living organism in response to an electrical stimulus. At the cellular level, this particular behavior seems to be present in many physiological processes such as embryogenesis, angiogenesis and tumor metastases. In vitro studies clearly showed that some types of cells, when subjected to electric fields of the same magnitude than the endogenous ones, tend to orientate and to migrate along the axes of the electrical field, targeting the cathode or to the anode depending on the cell type. The main objective of this work is the design and development of an electronic system capable to create and control galvanotactic events. We also performed some preliminary experiments finalized to test whether this device allows reproducing the galvanotaxis phenomena in a scientific and easily reproducible manner.

  16. Late post-irradiation phenomena in mammalain cell populations. Pt. 2. Intraclonal recovery in sublines isolated from X-irradiated L5178Y-S cell populations

    International Nuclear Information System (INIS)

    Beer, J.Z.

    1975-01-01

    Clonal analysis of L5178Y-S cell populations irradiated with 300 rads of X-rays indicates occurence of cell sublines with considerably prolonged mean doubling times up to 22 h as compared to 10-11 h for control. Subsequent observations of growth of the handicapped sublines derived from single cells showed capability of all more than 100 studied sublines to recover normal proliferative activity. This process of intraclonal recovery required in many cases longer periods of time, corresponding to many tens, sometimes more than 200, generations. Late intraclonal recovery was further analysed by subcloning. It was found that although cytochemically assayed viability of the handicapped sublines was normal, cloning efficiency strongly depended on the stage of the recovery process. The recovery processes occuring in clones isolated from irradiated cell populations were compared with analogous processes occuring in slowly growing sublines isolated from non-irradiated cell cultures. Marked differences in kinetics of these processes show that either they are different in sublines derived from irradiated and non-irradiated cell populations or that the mechanisms of the late intraclonal recovery are affected by radiation. The results presented allow to conclude that gradual post-irradiation recovery of growth depends primarily on formation, in the developing populations, of cells with higher proliferative activities. Possible nature of the recovery processes is discussed in the light of available information on mammalian somatic cell variants with altered drug or temperature sensitivity, or with nutritional requirements. A sequence is proposed of changes leading from radiation-induced disturbance of the normably existing equilibrium between three basic cell subpopulations to ultimate restoration of this equilibrium. (author)

  17. Altered Mycobacterium tuberculosis Cell Wall Metabolism and Physiology Associated With RpoB Mutation H526D

    Directory of Open Access Journals (Sweden)

    Victoria L. Campodónico

    2018-03-01

    Full Text Available Background:Mycobacterium tuberculosis (Mtb rpoB mutations are associated with global metabolic remodeling. However, the net effects of rpoB mutations on Mtb physiology, metabolism and function are not completely understood. Based on previous work, we hypothesized that changes in the expression of cell wall molecules in Mtb mutant RpoB 526D lead to changes in cell wall permeability and to altered resistance to environmental stresses and drugs.Methods: The phenotypes of a fully drug-susceptible clinical strain of Mtb and its paired rifampin-monoresistant, RpoB H526D mutant progeny strain were compared.Results: The rpoB mutant showed altered colony morphology, bacillary length and cell wall thickness, which were associated with increased cell wall permeability and susceptibility to the cell wall detergent sodium dodecyl sulfate (SDS after exposure to nutrient starvation. Relative to the isogenic rifampin-susceptible strain, the RpoB H526D mutant showed altered bacterial cellular metabolic activity and an eightfold increase in susceptibility to the cell-wall acting drug vancomycin.Conclusion: Our data suggest that RpoB mutation H526D is associated with altered cell wall physiology and resistance to cell wall-related stress. These findings are expected to contribute to an improved understanding of the pathogenesis of drug-resistant M. tuberculosis infections.

  18. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  19. Rheological phenomena in focus

    CERN Document Server

    Boger, DV

    1993-01-01

    More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be

  20. Mathematical physiology

    CERN Document Server

    Sneyd, James

    2009-01-01

    There has been a long history of interaction between mathematics and physiology. This book looks in detail at a wide selection of mathematical models in physiology, showing how physiological problems can be formulated and studied mathematically, and how such models give rise to interesting and challenging mathematical questions. With its coverage of many recent models it gives an overview of the field, while many older models are also discussed, to put the modern work in context. In this second edition the coverage of basic principles has been expanded to include such topics as stochastic differential equations, Markov models and Gibbs free energy, and the selection of models has also been expanded to include some of the basic models of fluid transport, respiration/perfusion, blood diseases, molecular motors, smooth muscle, neuroendrocine cells, the baroreceptor loop, turboglomerular oscillations, blood clotting and the retina. Owing to this extensive coverage, the second edition is published in two volumes. ...

  1. Physiological Functions and Regulation of the Na+/H+ Exchanger [NHE1] in Renal Tubule Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Patricia G Vallés

    2015-08-01

    Full Text Available The sodium-hydrogen exchanger isoform-1 [NHE1] is a ubiquitously expressed plasma membrane protein that plays a central role in intracellular pH and cell volume homeostasis by catalyzing an electroneutral exchange of extracellular sodium and intracellular hydrogen. Outside of this important physiological function, the NHE1 cytosolic tail domain acts as a molecular scaffold regulating cell survival and actin cytoskeleton organization through NHE1-dependent signaling proteins. NHE1 plays main roles in response to physiological stress conditions which in addition to cell shrinkage and acidification, include hypoxia and mechanical stimuli, such as cell stretch. NHE1-mediated modulation of programmed cell death results from the exchanger-mediated changes in pHi, cell volume, and/or [Na+]I; and, it has recently become known that regulation of cellular signaling pathways are involved as well. This review focuses on NHE1 functions and regulations. We describe evidence showing how these structural actions integrate with ion translocation in regulating renal tubule epithelial cell survival.

  2. Physiological role of Kv1.3 channel in T lymphocyte cell investigated quantitatively by kinetic modeling.

    Directory of Open Access Journals (Sweden)

    Panpan Hou

    Full Text Available Kv1.3 channel is a delayed rectifier channel abundant in human T lymphocytes. Chronic inflammatory and autoimmune disorders lead to the over-expression of Kv1.3 in T cells. To quantitatively study the regulatory mechanism and physiological function of Kv1.3 in T cells, it is necessary to have a precise kinetic model of Kv1.3. In this study, we firstly established a kinetic model capable to precisely replicate all the kinetic features for Kv1.3 channels, and then constructed a T-cell model composed of ion channels including Ca2+-release activated calcium (CRAC channel, intermediate K+ (IK channel, TASK channel and Kv1.3 channel for quantitatively simulating the changes in membrane potentials and local Ca2+ signaling messengers during activation of T cells. Based on the experimental data from current-clamp recordings, we successfully demonstrated that Kv1.3 dominated the membrane potential of T cells to manipulate the Ca2+ influx via CRAC channel. Our results revealed that the deficient expression of Kv1.3 channel would cause the less Ca2+ signal, leading to the less efficiency in secretion. This was the first successful attempt to simulate membrane potential in non-excitable cells, which laid a solid basis for quantitatively studying the regulatory mechanism and physiological role of channels in non-excitable cells.

  3. CdCl{sub 2} treatment related diffusion phenomena in Cd{sub 1−x}Zn{sub x}S/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kartopu, G., E-mail: giray.kartopu@glyndwr.ac.uk; Clayton, A. J.; Barrioz, V.; Lamb, D. A.; Irvine, S. J. C. [Centre for Solar Energy Research (CSER), Glyndŵr University, OpTIC, St. Asaph Business Park, St. Asaph LL17 0JD (United Kingdom); Taylor, A. A. [Physics Department, Durham University, Durham DH1 3LE (United Kingdom)

    2014-03-14

    Utilisation of wide bandgap Cd{sub 1−x}Zn{sub x}S alloys as an alternative to the CdS window layer is an attractive route to enhance the performance of CdTe thin film solar cells. For successful implementation, however, it is vital to control the composition and properties of Cd{sub 1−x}Zn{sub x}S through device fabrication processes involving the relatively high-temperature CdTe deposition and CdCl{sub 2} activation steps. In this study, cross-sectional scanning transmission electron microscopy and depth profiling methods were employed to investigate chemical and structural changes in CdTe/Cd{sub 1−x}Zn{sub x}S/CdS superstrate device structures deposited on an ITO/boro-aluminosilicate substrate. Comparison of three devices in different states of completion—fully processed (CdCl{sub 2} activated), annealed only (without CdCl{sub 2} activation), and a control (without CdCl{sub 2} activation or anneal)—revealed cation diffusion phenomena within the window layer, their effects closely coupled to the CdCl{sub 2} treatment. As a result, the initial Cd{sub 1−x}Zn{sub x}S/CdS bilayer structure was observed to unify into a single Cd{sub 1−x}Zn{sub x}S layer with an increased Cd/Zn atomic ratio; these changes defining the properties and performance of the Cd{sub 1−x}Zn{sub x}S/CdTe device.

  4. Bioelectrochemistry II membrane phenomena

    CERN Document Server

    Blank, M

    1987-01-01

    This book contains the lectures of the second course devoted to bioelectro­ chemistry, held within the framework of the International School of Biophysics. In this course another very large field of bioelectrochemistry, i. e. the field of Membrane Phenomena, was considered, which itself consists of several different, but yet related subfields. Here again, it can be easily stated that it is impossible to give a complete and detailed picture of all membrane phenomena of biological interest in a short course of about one and half week. Therefore the same philosophy, as the one of the first course, was followed, to select a series of lectures at postgraduate level, giving a synthesis of several membrane phenomena chosen among the most'important ones. These lectures should show the large variety of membrane-regulated events occurring in living bodies, and serve as sound interdisciplinary basis to start a special­ ized study of biological phenomena, for which the investigation using the dual approach, physico-che...

  5. Fundamentals of wave phenomena

    CERN Document Server

    Hirose, Akira

    2010-01-01

    This textbook provides a unified treatment of waves that either occur naturally or can be excited and propagated in various media. This includes both longitudinal and transverse waves. The book covers both mechanical and electrical waves, which are normally covered separately due to their differences in physical phenomena.

  6. Multiple regulatory roles of the mouse transmembrane adaptor protein NTAL in gene transcription and mast cell physiology.

    Directory of Open Access Journals (Sweden)

    Iva Polakovicova

    Full Text Available Non-T cell activation linker (NTAL; also called LAB or LAT2 is a transmembrane adaptor protein that is expressed in a subset of hematopoietic cells, including mast cells. There are conflicting reports on the role of NTAL in the high affinity immunoglobulin E receptor (FcεRI signaling. Studies carried out on mast cells derived from mice with NTAL knock out (KO and wild type mice suggested that NTAL is a negative regulator of FcεRI signaling, while experiments with RNAi-mediated NTAL knockdown (KD in human mast cells and rat basophilic leukemia cells suggested its positive regulatory role. To determine whether different methodologies of NTAL ablation (KO vs KD have different physiological consequences, we compared under well defined conditions FcεRI-mediated signaling events in mouse bone marrow-derived mast cells (BMMCs with NTAL KO or KD. BMMCs with both NTAL KO and KD exhibited enhanced degranulation, calcium mobilization, chemotaxis, tyrosine phosphorylation of LAT and ERK, and depolymerization of filamentous actin. These data provide clear evidence that NTAL is a negative regulator of FcεRI activation events in murine BMMCs, independently of possible compensatory developmental alterations. To gain further insight into the role of NTAL in mast cells, we examined the transcriptome profiles of resting and antigen-activated NTAL KO, NTAL KD, and corresponding control BMMCs. Through this analysis we identified several genes that were differentially regulated in nonactivated and antigen-activated NTAL-deficient cells, when compared to the corresponding control cells. Some of the genes seem to be involved in regulation of cholesterol-dependent events in antigen-mediated chemotaxis. The combined data indicate multiple regulatory roles of NTAL in gene expression and mast cell physiology.

  7. Utilization of physiological and taxonomic fluorescent probes to study Lactobacilli cells and response to pH challenge.

    Science.gov (United States)

    Olszewska, Magdalena A; Kocot, Aleksandra M; Nynca, Anna; Łaniewska-Trokenheim, Łucja

    2016-11-01

    pH stress is recognized as an important feature for Lactobacillus in relation to lifestyle and commercial utility. Hence, this study aims to investigate the cell function of Lactobacilli cells subjected to pHs between 7.0 and 2.0. For this purpose, the Lactobacilli isolates of vegetable origin were first hybridized with fluorescent oligonucleotide rRNA probes for detecting Lactobacillus species. Then, cells were exposed to pH stress and labelled with fluorescent probes, carboxyfluorescein diacetate (CFDA) and propidium iodine (PI), which provided the insight into esterase activity and membrane integrity of cells. Among isolates, fluorescence in situ hybridization (FISH) enabled us to specifically detect L. plantarum and L. brevis. Interestingly, FCM analysis revealed that at pHs between 7.0 and 4.0 the cell membrane was intact, while after the exposure at pH 3.0, and 2.0 became perturbed or impaired. Finally, L. brevis and L. plantarum differed from each other in fluorescence labeling behaviour and culturability. However, the results showed that the same standard protocol for labeling enables discrimination of subpopulations of tested species. Depending on the species, the substantial culturability loss was observed at pH 3.0 and 2.0. These results suggest that the taxonomic and physiological fluorescent probes could be suitable for in situ detection of specific bacteria and rapid assessment of the physiological status of cells. Copyright © 2016 Elsevier GmbH. All rights reserved.

  8. Unique combination of anatomy and physiology in cells of the rat paralaminar thalamic nuclei adjacent to the medial geniculate body.

    Science.gov (United States)

    Smith, Philip H; Bartlett, Edward L; Kowalkowski, Anna

    2006-05-20

    The medial geniculate body (MGB) has three major subdivisions, ventral (MGV), dorsal (MGD), and medial (MGM). MGM is linked with paralaminar nuclei that are situated medial and ventral to MGV/MGD. Paralaminar nuclei have unique inputs and outputs compared with MGV and MGD and have been linked to circuitry underlying some important functional roles. We recorded intracellularly from cells in the paralaminar nuclei in vitro. We found that they possess an unusual combination of anatomical and physiological features compared with those reported for "standard" thalamic neurons seen in the MGV/MGD and elsewhere in the thalamus. Compared with MGV/MGD neurons, anatomically, 1) paralaminar cell dendrites can be long, branch sparingly, and encompass a much larger area; 2) their dendrites may be smooth but can have well defined spines; and 3) their axons can have collaterals that branch locally within the same or nearby paralaminar nuclei. When compared with MGV/MGD neurons, physiologically, 1) their spikes are larger in amplitude and can be shorter in duration; 2) their spikes can have dual afterhyperpolarizations with fast and slow components; and 3) they can have a reduction or complete absence of the low-threshold, voltage-sensitive calcium conductance that reduces or eliminates the voltage-dependent burst response. We also recorded from cells in the parafascicular nucleus, a nucleus of the posterior intralaminar nuclear group, because they have unusual anatomical features that are similar to those of some of our paralaminar cells. As with the labeled paralaminar cells, parafascicular cells had physiological features distinguishing them from typical thalamic neurons. Copyright 2006 Wiley-Liss, Inc.

  9. Environmental physiology

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Summaries of research projects conducted during 1978 and 1979 are presented. Subject areas include: the effects of environmental pollutants on homeostasis of the hematopoietic system; pollutant effects on steroid metabolism; pollutant effects on pulmonary macrophages; effects of toxic gases on lung cells; the development of immunological methods for assessing lung damage at the cellular level; the response of erythropoietin concentration to various physiological changes; and the study of actinide metabolism in monkey skeletons

  10. Theory of threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel

    2002-01-01

    Theory of Threshold Phenomena in Quantum Scattering is developed in terms of Reduced Scattering Matrix. Relationships of different types of threshold anomalies both to nuclear reaction mechanisms and to nuclear reaction models are established. Magnitude of threshold effect is related to spectroscopic factor of zero-energy neutron state. The Theory of Threshold Phenomena, based on Reduced Scattering Matrix, does establish relationships between different types of threshold effects and nuclear reaction mechanisms: the cusp and non-resonant potential scattering, s-wave threshold anomaly and compound nucleus resonant scattering, p-wave anomaly and quasi-resonant scattering. A threshold anomaly related to resonant or quasi resonant scattering is enhanced provided the neutron threshold state has large spectroscopic amplitude. The Theory contains, as limit cases, Cusp Theories and also results of different nuclear reactions models as Charge Exchange, Weak Coupling, Bohr and Hauser-Feshbach models. (author)

  11. In vitro investigations of Cynara scolymus L. extract on cell physiology of HepG2 liver cells

    Directory of Open Access Journals (Sweden)

    Gesine Löhr

    2009-06-01

    Full Text Available The objective of this study was the investigation of a potential influence of artichoke leaf extract (ALE on the cell physiology and gene expression of phase I/II enzymes of human liver cells HepG2 and investigation on potential cell protective effects against ethanol-induced cell toxicity against HepG2 cells. Cell biological assays under in vitro conditions using HepG2 liver cells and investigation of mitochondrial activity (MTT test, proliferation assay (BrdU incorporation ELISA, LDH as toxicity marker, gene expression analysis by RT-PCR and enzyme activity of glutationtransferase. Artichocke extract, containing 27% caffeoylquinic acids and 7% flavonoids induced mitochondrial activity, proliferation and total protein content under in vitro conditions in human liver cells HepG2. These effects could not be correlated to the well-known artichoke secondary compounds cynarin, caffeic acid, chlorogenic acid, luteolin and luteolin-7-O-glucoside. The flavones luteolin and luteolin-7-O-glucoside had inhibitory effects at 100 µg/mL level on HepG2 cells, with luteolin being a significant stronger inhibitor compared to the respective glucoside. Artichoke leaf extract had minor stimulating effect on gene expression of CYP1A2, while CYP3A4, GGT, GPX2, GSR and GST were slightly inhibited. GST inhibition under in vitro conditions was also shown by quantification of GST enzyme activity. Induction of gene expression of CYP1A2 was shown to be supraadditive after simultaneous application of ethanol plus artichoke extract. Artichoke leaf extract exhibited cell protective effects against ethanol-induced toxicity within cotreatment under in vitro conditions. Also H2O2 damage was significantly inhibited by simultaneous artichoke incubation. Pre- and posttreatments did not exert protective effects. DMSO-induced toxicity was significantly reduced by pre-, post- and cotreatment with artichoke extract and especially with luteolin-7-O-glucoside, indicating a direct

  12. Transport phenomena in nanofluidics

    OpenAIRE

    Schoch, Reto Bruno; Han, J.; Renaud, Philippe

    2008-01-01

    Transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100 nm renders possible phenomena that are not accessible at bigger length scales. This research field is termed nanofluidics and received its name only recently, but the roots in science and technology are broad. Nanofluidics has experienced a big growth during the last few years, confirmed by significant scientific and practical achievements. This review focuses on physical proper...

  13. Transport phenomena II essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena II covers forced convention, temperature distribution, free convection, diffusitivity and the mechanism of mass transfer, convective mass transfer, concentration

  14. Large momentum transfer phenomena

    International Nuclear Information System (INIS)

    Imachi, Masahiro; Otsuki, Shoichiro; Matsuoka, Takeo; Sawada, Shoji.

    1978-01-01

    The large momentum transfer phenomena in hadron reaction drastically differ from small momentum transfer phenomena, and are described in this paper. Brief review on the features of the large transverse momentum transfer reactions is described in relation with two-body reactions, single particle productions, particle ratios, two jet structure, two particle correlations, jet production cross section, and the component of momentum perpendicular to the plane defined by the incident protons and the triggered pions and transverse momentum relative to jet axis. In case of two-body process, the exponent N of the power law of the differential cross section is a value between 10 to 11.5 in the large momentum transfer region. The breaks of the exponential behaviors into the power ones are observed at the large momentum transfer region. The break would enable to estimate the order of a critical length. The large momentum transfer phenomena strongly suggest an important role of constituents of hadrons in the hard region. Hard rearrangement of constituents from different initial hadrons induces large momentum transfer reactions. Several rules to count constituents in the hard region have been proposed so far to explain the power behavior. Scale invariant quark interaction and hard reactions are explained, and a summary of the possible types of hard subprocess is presented. (Kato, T.)

  15. Adult Stem Cell-Derived Kidney Organoids to Model Tissue Physiology and Disease

    NARCIS (Netherlands)

    Schutgens, Frans

    2017-01-01

    “Organoid” is defined as a 3D structure grown from stem cells and consisting of organ-specific cell types that self-organizes through cell sorting and spatially restricted lineage commitment. Organoids can be derived from either adult stem cells (ASCs) or pluripotent stem cells (PSCs). The

  16. Development of a novel, physiologically relevant cytotoxicity model: Application to the study of chemotherapeutic damage to mesenchymal stromal cells

    Energy Technology Data Exchange (ETDEWEB)

    May, Jennifer E., E-mail: Jennifer2.May@uwe.ac.uk; Morse, H. Ruth, E-mail: Ruth.Morse@uwe.ac.uk; Xu, Jinsheng, E-mail: Jinsheng.Xu@uwe.ac.uk; Donaldson, Craig, E-mail: Craig.Donaldson@uwe.ac.uk

    2012-09-15

    There is an increasing need for development of physiologically relevant in-vitro models for testing toxicity, however determining toxic effects of agents which undergo extensive hepatic metabolism can be particularly challenging. If a source of such metabolic enzymes is inadequate within a model system, toxicity from prodrugs may be grossly underestimated. Conversely, the vast majority of agents are detoxified by the liver, consequently toxicity from such agents may be overestimated. In this study we describe the development of a novel in-vitro model, which could be adapted for any toxicology setting. The model utilises HepG2 liver spheroids as a source of metabolic enzymes, which have been shown to more closely resemble human liver than traditional monolayer cultures. A co-culture model has been developed enabling the effect of any metabolised agent on another cell type to be assessed. This has been optimised to enable the study of damaging effects of chemotherapy on mesenchymal stem cells (MSC), the supportive stem cells of the bone marrow. Several optimisation steps were undertaken, including determining optimal culture conditions, confirmation of hepatic P450 enzyme activity and ensuring physiologically relevant doses of chemotherapeutic agents were appropriate for use within the model. The developed model was subsequently validated using several chemotherapeutic agents, both prodrugs and active drugs, with resulting MSC damage closely resembling effects seen in patients following chemotherapy. Minimal modifications would enable this novel co-culture model to be utilised as a general toxicity model, contributing to the drive to reduce animal safety testing and enabling physiologically relevant in-vitro study. -- Highlights: ► An in vitro model was developed for study of drugs requiring hepatic metabolism ► HepG2 spheroids were utilised as a physiologically relevant source of liver enzymes ► The model was optimised to enable study of chemotherapeutic

  17. Development of a novel, physiologically relevant cytotoxicity model: Application to the study of chemotherapeutic damage to mesenchymal stromal cells

    International Nuclear Information System (INIS)

    May, Jennifer E.; Morse, H. Ruth; Xu, Jinsheng; Donaldson, Craig

    2012-01-01

    There is an increasing need for development of physiologically relevant in-vitro models for testing toxicity, however determining toxic effects of agents which undergo extensive hepatic metabolism can be particularly challenging. If a source of such metabolic enzymes is inadequate within a model system, toxicity from prodrugs may be grossly underestimated. Conversely, the vast majority of agents are detoxified by the liver, consequently toxicity from such agents may be overestimated. In this study we describe the development of a novel in-vitro model, which could be adapted for any toxicology setting. The model utilises HepG2 liver spheroids as a source of metabolic enzymes, which have been shown to more closely resemble human liver than traditional monolayer cultures. A co-culture model has been developed enabling the effect of any metabolised agent on another cell type to be assessed. This has been optimised to enable the study of damaging effects of chemotherapy on mesenchymal stem cells (MSC), the supportive stem cells of the bone marrow. Several optimisation steps were undertaken, including determining optimal culture conditions, confirmation of hepatic P450 enzyme activity and ensuring physiologically relevant doses of chemotherapeutic agents were appropriate for use within the model. The developed model was subsequently validated using several chemotherapeutic agents, both prodrugs and active drugs, with resulting MSC damage closely resembling effects seen in patients following chemotherapy. Minimal modifications would enable this novel co-culture model to be utilised as a general toxicity model, contributing to the drive to reduce animal safety testing and enabling physiologically relevant in-vitro study. -- Highlights: ► An in vitro model was developed for study of drugs requiring hepatic metabolism ► HepG2 spheroids were utilised as a physiologically relevant source of liver enzymes ► The model was optimised to enable study of chemotherapeutic

  18. Aqueous extracts and polysaccharides from Marshmallow roots (Althea officinalis L.): cellular internalisation and stimulation of cell physiology of human epithelial cells in vitro.

    Science.gov (United States)

    Deters, Alexandra; Zippel, Janina; Hellenbrand, Nils; Pappai, Dirk; Possemeyer, Cathleen; Hensel, Andreas

    2010-01-08

    Aqueous extracts from the roots of Althea officinalis L. (Malvaceae) are widely used for treatment of irritated mucosa. The clinical proven effects are related to the presence of bioadhesive and mucilaginous polysaccharides from the rhamnogalacturonan type, leading to the physical formation of mucin-like on top of the irritated tissues. No data are available if the extracts or the polysaccharides from these extract exert an active influence on mucosal or connective tissue cells, in order to initiated changes in cell physiology, useful for better tissue regeneration. In vitro investigations of aqueous A. officinalis extract AE and raw polysaccharides (RPS) on epithelial KB cells and primary dermal human fibroblasts (pNHF) using WST1 vitality test and BrdU proliferation ELISA. Gene expression analysis by microarray from KB cells. Internalisation studies of polysaccharides were performed by laser scanning microscopy. AE (1, 10 microg/mL) had stimulating effect on cell viability and proliferation of epithelial KB cells. RPS (1, 10 microg/mL) stimulated cell vitality of epithelial cells significantly without triggering the cells into higher proliferation status. Neither AE nor RPS had any effect on fibroblasts. FITC-labeled RPS was shown to be internalised into epithelial cells, but not into fibroblasts. FITC-RPS was shown to form bioadhesive layers on the cell surface of dermal fibroblasts. Microarray analysis indicated an up-regulation of genes related to cell adhesion proteins, growth regulators, extracellular matrix, cytokine release and apoptosis. Aqueous extracts and polysaccharides from the roots of A. officinalis are effective stimulators of cell physiology of epithelial cells which can prove the traditional use of Marshmallow preparations for treatment of irritated mucous membranes within tissue regeneration. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  19. Accelerated generation of human induced pluripotent stem cells with retroviral transduction and chemical inhibitors under physiological hypoxia

    International Nuclear Information System (INIS)

    Shimada, Hidenori; Hashimoto, Yoshiya; Nakada, Akira; Shigeno, Keiji; Nakamura, Tatsuo

    2012-01-01

    Highlights: ► Very rapid generation of human iPS cells under optimized conditions. ► Five chemical inhibitors under hypoxia boosted reprogramming. ► We performed genome-wide DNA methylation analysis. -- Abstract: Induced pluripotent stem (iPS) cells are generated from somatic cells by the forced expression of a defined set of pluripotency-associated transcription factors. Human iPS cells can be propagated indefinitely, while maintaining the capacity to differentiate into all cell types in the body except for extra-embryonic tissues. This technology not only represents a new way to use individual-specific stem cells for regenerative medicine but also constitutes a novel method to obtain large amounts of disease-specific cells for biomedical research. Despite their great potential, the long reprogramming process (up to 1 month) remains one of the most significant challenges facing standard virus-mediated methodology. In this study, we report the accelerated generation of human iPS cells from adipose-derived stem (ADS) cells, using a new combination of chemical inhibitors under a setting of physiological hypoxia in conjunction with retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Under optimized conditions, we observed human embryonic stem (ES)-like cells as early as 6 days after the initial retroviral transduction. This was followed by the emergence of fully reprogrammed cells bearing Tra-1-81-positive and DsRed transgene-silencing properties on day 10. The resulting cell lines resembled human ES cells in many respects including proliferation rate, morphology, pluripotency-associated markers, global gene expression patterns, genome-wide DNA methylation states, and the ability to differentiate into all three of the germ layers, both in vitro and in vivo. Our method, when combined with chemical inhibitors under conditions of physiological hypoxia, offers a powerful tool for rapidly generating bona fide human iPS cells and facilitates the application of i

  20. Accelerated generation of human induced pluripotent stem cells with retroviral transduction and chemical inhibitors under physiological hypoxia

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hidenori [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Hashimoto, Yoshiya [Department of Biomaterials, Osaka Dental University, 8-1, Hanazonocho, Kuzuha, Hirakatashi, Osaka 573-1121 (Japan); Nakada, Akira; Shigeno, Keiji [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Nakamura, Tatsuo, E-mail: nakamura@frontier.kyoto-u.ac.jp [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Very rapid generation of human iPS cells under optimized conditions. Black-Right-Pointing-Pointer Five chemical inhibitors under hypoxia boosted reprogramming. Black-Right-Pointing-Pointer We performed genome-wide DNA methylation analysis. -- Abstract: Induced pluripotent stem (iPS) cells are generated from somatic cells by the forced expression of a defined set of pluripotency-associated transcription factors. Human iPS cells can be propagated indefinitely, while maintaining the capacity to differentiate into all cell types in the body except for extra-embryonic tissues. This technology not only represents a new way to use individual-specific stem cells for regenerative medicine but also constitutes a novel method to obtain large amounts of disease-specific cells for biomedical research. Despite their great potential, the long reprogramming process (up to 1 month) remains one of the most significant challenges facing standard virus-mediated methodology. In this study, we report the accelerated generation of human iPS cells from adipose-derived stem (ADS) cells, using a new combination of chemical inhibitors under a setting of physiological hypoxia in conjunction with retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Under optimized conditions, we observed human embryonic stem (ES)-like cells as early as 6 days after the initial retroviral transduction. This was followed by the emergence of fully reprogrammed cells bearing Tra-1-81-positive and DsRed transgene-silencing properties on day 10. The resulting cell lines resembled human ES cells in many respects including proliferation rate, morphology, pluripotency-associated markers, global gene expression patterns, genome-wide DNA methylation states, and the ability to differentiate into all three of the germ layers, both in vitro and in vivo. Our method, when combined with chemical inhibitors under conditions of physiological hypoxia, offers a powerful tool for rapidly

  1. A biomimetic physiological model for human adipose tissue by adipocytes and endothelial cell cocultures with spatially controlled distribution

    International Nuclear Information System (INIS)

    Yao, Rui; Zhang, Renji; Lin, Feng; Du, Yanan; Luan, Jie

    2013-01-01

    An in vitro model that recapitulates the characteristics of native human adipose tissue would largely benefit pathology studies and therapy development. In this paper, we fabricated a physiological model composed of both human adipocytes and endothelial cells with spatially controlled distribution that biomimics the structure and composition of human adipose tissue. Detailed studies into the cell–cell interactions between the adipocytes and endothelial cells revealed a mutual-enhanced effect which resembles the in vivo routine. Furthermore, comparisons between planar coculture and model coculture demonstrated improved adipocyte function as well as endothelial cell proliferation under the same conditions. This research provided a reliable model for human adipose tissue development studies and potential obesity-related therapy development. (paper)

  2. Programming and isolation of highly pure physiologically and pharmacologically functional sinus-nodal bodies from pluripotent stem cells.

    Science.gov (United States)

    Jung, Julia Jeannine; Husse, Britta; Rimmbach, Christian; Krebs, Stefan; Stieber, Juliane; Steinhoff, Gustav; Dendorfer, Andreas; Franz, Wolfgang-Michael; David, Robert

    2014-05-06

    Therapeutic approaches for "sick sinus syndrome" rely on electrical pacemakers, which lack hormone responsiveness and bear hazards such as infection and battery failure. These issues may be overcome via "biological pacemakers" derived from pluripotent stem cells (PSCs). Here, we show that forward programming of PSCs with the nodal cell inducer TBX3 plus an additional Myh6-promoter-based antibiotic selection leads to cardiomyocyte aggregates consisting of >80% physiologically and pharmacologically functional pacemaker cells. These induced sinoatrial bodies (iSABs) exhibited highly increased beating rates (300-400 bpm), coming close to those found in mouse hearts, and were able to robustly pace myocardium ex vivo. Our study introduces iSABs as highly pure, functional nodal tissue that is derived from PSCs and may be important for future cell therapies and drug testing in vitro.

  3. Injuries in exponential phase cells of escherichia coli suspended in physiological phosphate buffered saline by far-infrared irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sawai, J.; Sagara, K.; Miyagawa, M.; Kokugan, T.; Shimizu, M. [Tokyo Univ of Agriculture & Technology Tokyo (Japan). Department of Chemical Engineering, Division of Applied Chemistry; Igarashi, H. [Tokyo Metropolitan Research Laboratory of Public (Japan)

    1997-08-01

    The pasteurization effect of far-infrared (FIR) radiation on Escherichia coli suspended in physiological phosphate buffered saline in the exponential growth phase (exponential phase) was studied. FIR irradiation decreased the number of viable cells in their exponential phase more rapidly than that in their stationary growth phase (stationary phase). By using four kinds of antibiotics as selective reagents to examine the injuries of bacteria, the damaged parts induced by FIR irradiation were specified on the basis of the changes in sensitivities to selective reagents. FIR irradiation damaged mainly RNA polymerize of E. coli in the exponential phase. Under the condition that the transient behavior of the bulk temperature of bacterial suspension irradiated by FIR was the same as that heated by thermal conduction, the pasteurization effect by FIR irradiation on the exponential phase cells was much greater than that by thermal conduction. However, both FIR irradiation and thermal conductive heating induced similar changes in the sensitivities to selective reagents for the exponential phase cells of E. coli. Under the same irradiation conditions, the changes in sensitivities to the selective reagents for the exponential phase cells were different from those for the stationary phase cells. The injuries of ribosome in the exponential phase cells were not as serious as those in the stationary phase cells. It was suggested that the mechanisms of death of the exponential phase cells and the stationary phase cells were different from each other. 29 refs., 9 figs.

  4. Single-cell behavior and population heterogeneity: solving an inverse problem to compute the intrinsic physiological state functions.

    Science.gov (United States)

    Spetsieris, Konstantinos; Zygourakis, Kyriacos

    2012-04-15

    The dynamics of isogenic cell populations can be described by cell population balance models that account for phenotypic heterogeneity. To utilize the predictive power of these models, however, we must know the rates of single-cell reaction and division and the bivariate partition probability density function. These three intrinsic physiological state (IPS) functions can be obtained by solving an inverse problem that requires knowledge of the phenotypic distributions for the overall cell population, the dividing cell subpopulation and the newborn cell subpopulation. We present here a robust computational procedure that can accurately estimate the IPS functions for heterogeneous cell populations. A detailed parametric analysis shows how the accuracy of the inverse solution is affected by discretization parameters, the type of non-parametric estimators used, the qualitative characteristics of phenotypic distributions and the unknown partitioning probability density function. The effect of finite sampling and measurement errors on the accuracy of the recovered IPS functions is also assessed. Finally, we apply the procedure to estimate the IPS functions of an E. coli population carrying an IPTG-inducible genetic toggle network. This study completes the development of an integrated experimental and computational framework that can become a powerful tool for quantifying single-cell behavior using measurements from heterogeneous cell populations. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. A human-like senescence-associated secretory phenotype is conserved in mouse cells dependent on physiological oxygen.

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Coppé

    2010-02-01

    Full Text Available Cellular senescence irreversibly arrests cell proliferation in response to oncogenic stimuli. Human cells develop a senescence-associated secretory phenotype (SASP, which increases the secretion of cytokines and other factors that alter the behavior of neighboring cells. We show here that "senescent" mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions (20% oxygen, do not express a human-like SASP, and differ from similarly cultured human cells in other respects. However, when cultured in physiological (3% oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP. We describe two new aspects of the human and mouse SASPs. First, cells from both species upregulated the expression and secretion of several matrix metalloproteinases, which comprise a conserved genomic cluster. Second, for both species, the ability to promote the growth of premalignant epithelial cells was due primarily to the conserved SASP factor CXCL-1/KC/GRO-alpha. Further, mouse fibroblasts made senescent in 3%, but not 20%, oxygen promoted epithelial tumorigenesis in mouse xenographs. Our findings underscore critical mouse-human differences in oxygen sensitivity, identify conditions to use mouse cells to model human cellular senescence, and reveal novel conserved features of the SASP.

  6. A chemical signal possibly related to physiology in fossil cells detected by energy dispersive X-ray microanalysis.

    Science.gov (United States)

    Wang, X

    2006-02-01

    Energy dispersive X-ray microanalysis (EDXMA) is a widely used tool employed to detect elemental composition and its spatial distribution in a sample without causing damage. Charcoalified cytoplasm is a new type of fossil material that came to people's attention only recently. In this paper, EDXMA is used for the first time to detect the spatial elemental distribution in charcoalified cytoplasm of two fossil plants that are more than 100 million years old. The results demonstrate certain elemental distribution patterns within charcoalified cytoplasm and the surrounding cell walls. Based on the results from cytological studies of extant material, the heterogeneous spatial elemental distribution within the charcoalified cytoplasm has the potential to be related to the maturation of cells, the presence of certain organelles, and the physiology of these organelles. This is the first chemical signal detected in cytoplasm residue that can possibly be related to plant physiology. This paves the way for further research on fossil cytoplasm, which will better our understanding on the physiology of fossil plants.

  7. Nanoparticle-based and bioengineered probes and sensors to detect physiological and pathological biomarkers in neural cells

    Directory of Open Access Journals (Sweden)

    Dusica eMaysinger

    2015-12-01

    Full Text Available Nanotechnology, a rapidly evolving field, provides simple and practical tools to investigate the nervous system in health and disease. Among these tools are nanoparticle-based probes and sensors that detect biochemical and physiological properties of neurons and glia, and generate signals proportionate to physical, chemical, and/or electrical changes in these cells. In this context, quantum dots (QDs, carbon-based structures (C-dots, graphene and nanodiamonds and gold nanoparticles are the most commonly used nanostructures. They can detect and measure enzymatic activities of proteases (metalloproteinases, caspases, ions, metabolites, and other biomolecules under physiological or pathological conditions in neural cells. Here, we provide some examples of nanoparticle-based and genetically engineered probes and sensors that are used to reveal changes in protease activities and calcium ion concentrations. Although significant progress in developing these tools has been made for probing neural cells, several challenges remain. We review many common hurdles in sensor development, while highlighting certain advances. In the end, we propose some future directions and ideas for developing practical tools for neural cell investigations, based on the maxim Measure what is measurable, and make measurable what is not so (Galileo Galilei.

  8. CD4+CD25+ regulatory T cells: I. Phenotype and physiology

    DEFF Research Database (Denmark)

    Holm, Thomas Lindebo; Nielsen, Janne; Claesson, Mogens H

    2004-01-01

    it has become increasingly clear that regulatory CD4+CD25+ T cells (Treg cells) play an important role in the maintenance of immunological self-tolerance, and that this cell subset exerts its function by suppressing the proliferation or function of autoreactive T cells. Based on human and murine...

  9. A Brief History of Bacterial Growth Physiology

    Directory of Open Access Journals (Sweden)

    Moselio eSchaechter

    2015-04-01

    Full Text Available Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid 19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism.Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the Copenhagen School. During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell.Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs.

  10. Possible harmful effects on central nervous system cells in the use of physiological saline as an irrigant during neurosurgical procedures.

    Science.gov (United States)

    Uchida, Koichi; Yamada, Motoyuki; Hayashi, Takuro; Mine, Yutaka; Kawase, Takeshi

    2004-08-01

    Physiologic saline is routinely used as an irrigant in neurosurgery especially in Japan. Cerebrospinal fluid (CSF) differs from physiologic saline in its concentration of inorganic salts, osmolality, and pH and is completely different insofar as it contains glucose, protein, cholesterol, and other lipids. The present study was designed to compare the possible functional and morphologic deleterious influence of these differences on cultured rat neural cells using saline (S), Ringer's solution with glucose (Lactec G, LG; Otsuka Pharmaceutical Co.; Tokyo, Japan) and without glucose (Lactec, L; Otsuka Pharmaceutical Co.), and an artificial CSF (ACSF). Primary cultured rat neurons and astrocytes were divided into five groups according to the medium used, the four experimental groups (ACSF, L, LG, and S) and one control group (C). At various time points up to 24 hours, the rhodamine 123 uptake by neuronal or astrocytic cellular mitochondria was evaluated as cell function assessment. Morphologic assessment for both neuron and astrocyte culture was carried out with scanning electron microscopy (SEM) at the 24-hour time point. SEM showed little difference between the C and ACSF groups, whereas morphologic deterioration was particularly severe in the S group for both neurons and astrocytes. In the case of neuronal mitochondrial activity, the L and S groups demonstrated respectively severe and some deterioration, particularly in the mitochondria of the neuronal processes. The deleterious effects in mitochondrial activity of the S group were even more apparent in the astrocytic cells. These results suggest that physiologic saline, when used as an irrigant in neurologic surgery, might in some circumstances cause damage to exposed and compromised neural cells.

  11. C. albicans increases cell wall mannoprotein, but not mannan, in response to blood, serum and cultivation at physiological temperature

    Science.gov (United States)

    Kruppa, Michael; Greene, Rachel R; Noss, Ilka; Lowman, Douglas W; Williams, David L

    2011-01-01

    The cell wall of Candida albicans is central to the yeasts ability to withstand osmotic challenge, to adhere to host cells, to interact with the innate immune system and ultimately to the virulence of the organism. Little is known about the effect of culture conditions on the cell wall structure and composition of C. albicans. We examined the effect of different media and culture temperatures on the molecular weight (Mw), polymer distribution and composition of cell wall mannan and mannoprotein complex. Strain SC5314 was inoculated from frozen stock onto yeast peptone dextrose (YPD), blood or 5% serum agar media at 30 or 37°C prior to mannan/mannoprotein extraction. Cultivation of the yeast in blood or serum at physiologic temperature resulted in an additive effect on Mw, however, cultivation media had the greatest impact on Mw. Mannan from a yeast grown on blood or serum at 30°C showed a 38.9 and 28.6% increase in Mw, when compared with mannan from YPD-grown yeast at 30°C. Mannan from the yeast pregrown on blood or serum at 37°C showed increased Mw (8.8 and 26.3%) when compared with YPD mannan at 37°C. The changes in Mw over the entire polymer distribution were due to an increase in the amount of mannoprotein (23.8–100%) and a decrease in cell wall mannan (5.7–17.3%). We conclude that C. albicans alters the composition of its cell wall, and thus its phenotype, in response to cultivation in blood, serum and/or physiologic temperature by increasing the amount of the mannoprotein and decreasing the amount of the mannan in the cell wall. PMID:21515585

  12. Evolutionary phenomena in galaxies

    International Nuclear Information System (INIS)

    Beckman, J.E.; Pagel, B.E.J.

    1989-01-01

    This book reviews the subject of evolutionary phenomena in galaxies, bringing together contributions by experts on all the relevant physics and astrophysics necessary to understand galaxies and how they work. The book is based on the proceedings of a conference held in July 1988 in Puerto de la Cruz, Tenerife which was timed to coincide with the first year of operation of the 4.2 m William Herschel Telescope. The broad topics covered include formation of galaxies and their ages, stellar dynamics, galactic scale gas and its role in star formation and the production and distribution of the chemical elements within galaxies. (author)

  13. Solid state phenomena

    CERN Document Server

    Lawrance, R

    1972-01-01

    Solid State Phenomena explores the fundamentals of the structure and their influence on the properties of solids. This book is composed of five chapters that focus on the electrical and thermal conductivities of crystalline solids. Chapter 1 describes the nature of solids, particularly metals and crystalline materials. This chapter also presents a model to evaluate crystal structure, the forces between atom pairs, and the mechanism of plastic and elastic deformation. Chapter 2 demonstrates random vibrations of atoms in a solid using a one-dimensional array, while Chapter 3 examines the resista

  14. Transport phenomena I essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena I includes viscosity, flow of Newtonian fluids, velocity distribution in laminar flow, velocity distributions with more than one independent variable, thermal con

  15. Crystallography and Magnetic Phenomena

    Directory of Open Access Journals (Sweden)

    Vojtěch Kopský

    2015-02-01

    Full Text Available This essay describes the development of groups used for the specification of symmetries from ordinary and magnetic point groups to Fedorov and magnetic space groups, as well as other varieties of groups useful in the study of symmetric objects. In particular, we consider the problem of some incorrectness in Vol. A of the International Tables for Crystallography. Some results of tensor calculus are presented in connection with magnetoelectric phenomena, where we demonstrate the use of Ascher’s trinities and Opechowski’s magic relations and their connection. Specific tensor decomposition calculations on the grounds of Clebsch Gordan products are illustrated.

  16. Chemical composition of Enterococcus faecalis in biofilm cells initiated from different physiologic states.

    Science.gov (United States)

    Liu, Hongyan; Xu, Qiong; Huo, Lijun; Wei, Xi; Ling, Junqi

    2014-09-01

    Enterococcus faecalis is a ubiquitous bacterium of the gut that is observed in persistent periradicular infections. Its pathogenicity is associated with biofilm formation and the ability to survive under nutrient-poor (starvation) conditions. However, characteristics of chemical composition of biofilm cells developed by starved E. faecalis cells remain poorly understood. In this study, E. faecalis cells in exponential, stationary, and starvation phases were prepared and separately cultured to form biofilms. Confocal laser scanning microscopy was performed to verify biofilm formation. Raman microscopy was used to investigate the chemical composition of cells within the biofilms. Compared to cells in exponential or stationary phase, starved cells developed biofilms with fewer culturable cells (P cells produced in the biofilms from starved planktonic cells contained more protein and less nucleic acids than either the corresponding planktonic cells or the cells in biofilms from planktonic cells in exponential or stationary phases, suggesting that biofilm-grown cells from the starvation phase were characterized by increased synthesis of proteins and decreased nucleic acids. This study provides an insight into the chemical composition of biofilm cells developed by starved E. faecalis.

  17. Direct channel problems and phenomena

    International Nuclear Information System (INIS)

    Cutkosky, R.E.

    1975-01-01

    Direct channel problems and phenomena are considered covering the need for precision hadron spectroscopy, the data base for precision hadron spectroscopy, some relations between direct-channel and cross-channel effects, and spin rotation phenomena

  18. Molecular crowding defines a common origin for the Warburg effect in proliferating cells and the lactate threshold in muscle physiology.

    Directory of Open Access Journals (Sweden)

    Alexei Vazquez

    2011-04-01

    Full Text Available Aerobic glycolysis is a seemingly wasteful mode of ATP production that is seen both in rapidly proliferating mammalian cells and highly active contracting muscles, but whether there is a common origin for its presence in these widely different systems is unknown. To study this issue, here we develop a model of human central metabolism that incorporates a solvent capacity constraint of metabolic enzymes and mitochondria, accounting for their occupied volume densities, while assuming glucose and/or fatty acid utilization. The model demonstrates that activation of aerobic glycolysis is favored above a threshold metabolic rate in both rapidly proliferating cells and heavily contracting muscles, because it provides higher ATP yield per volume density than mitochondrial oxidative phosphorylation. In the case of muscle physiology, the model also predicts that before the lactate switch, fatty acid oxidation increases, reaches a maximum, and then decreases to zero with concomitant increase in glucose utilization, in agreement with the empirical evidence. These results are further corroborated by a larger scale model, including biosynthesis of major cell biomass components. The larger scale model also predicts that in proliferating cells the lactate switch is accompanied by activation of glutaminolysis, another distinctive feature of the Warburg effect. In conclusion, intracellular molecular crowding is a fundamental constraint for cell metabolism in both rapidly proliferating- and non-proliferating cells with high metabolic demand. Addition of this constraint to metabolic flux balance models can explain several observations of mammalian cell metabolism under steady state conditions.

  19. Influence of physiological environment on the expression of thermotolerance in proliferating (P) and quiescent (Q) tumor cells

    International Nuclear Information System (INIS)

    Wallen, C.A.; Gutierrez, R.H.

    1987-01-01

    Alteration of the physiological environment of Q 66 and 67 mouse mammary tumor cells by placing them in either fresh, complete medium or a balanced salt solution supplemented with 24 mM glucose resulted in a significant increase in the time at 45 0 C necessary to measure cytotoxicity. The degree of increased resistance was dependent on the solution used to change the environment and the length of time the cells were allowed to equilibrate in this new environment. The aim of the present study is to determine if alterations in the Q cell environment has significant effects on the expression of thermotolerance. Pure P and Q cell populations of both 66 and 67 cell lines are exposed continuously to either 42 or 43 0 C and assayed for colony formation at various times for the development of thermotolerance. The comparison of thermotolerance development both in terms of time course and extent are measured in Q cells under 5 conditions: 1) normal, depleted medium (pH 6.8), 2) fresh, complete medium (pH 7.2), 3) balanced salt solution with 24 mM glucose (pH 7.2), 4) balanced salt solution with no glucose (pH 7.2), and 5) depleted medium supplemented with fresh serum (pH 6.8). These data have implications for the importance of Q cells in determining the outcome of clinical hyperthermia and the role of other stressors on the expression of thermotolerance

  20. Physiology of natural killer cells. In vivo regulation of progenitors by interleukin 3

    International Nuclear Information System (INIS)

    Kalland, T.

    1987-01-01

    Adoptive transfer of bone marrow cells to syngeneic lethally irradiated C57BL/6 mice was used to study the maturation of natural killer (NK) cells from their progenitors. The NK progenitor cell was found to be asialomonoganglioside-negative, (aGM1-) Thy-1-, NK-1-, Ly-1-, Ly-2-, and L3T4-. The NK cells emerging from the bone marrow grafts were aGM1+, NK-1+, Thy-1+/-, Ly-1-, Ly-2-, and L3T4- and to have a target specter similar to that of NK cells isolated from the spleen of normal mice. The regulatory role of interleukin 2 (IL-2) and interleukin 3 (IL-3) for the maturation of NK cells was examined by exposure of the bone marrow cells to the lymphokines in vitro before bone marrow grafting or by treatment of bone marrow-grafted mice with lymphokines through s.c. implanted miniosmotic pumps. IL-3 antagonized the IL-2-induced maturation of NK cells in vitro and strongly inhibited the generation of NK cells after adoptive transfer of bone marrow cells in vivo. The suppressive effect of IL-3 was evident throughout the treatment period (8 or 16 days) but was apparently reversible because NK activity returned to control levels within 8 days after cessation of treatment. The inhibition of cytotoxic activity was accompanied by a reduced appearance of cells with the NK phenotypic markers aGM1 or NK-1, indicating that not only the cytotoxic activity of NK cells but also their actual formation was inhibited. Concomitantly, a moderate increase in cells expressing the T cell marker L3T4 and an increased proliferative response to the T cell mitogen concanavalin A was observed. A direct estimate of the effect of IL-3 on the frequency of NK cell progenitors was obtained by limiting dilution analysis of bone marrow cells at day 8 after bone marrow transplantation

  1. Selection and physiology of cell cultures of Douglas-fir grown under conditions of water stress.

    Science.gov (United States)

    Leustek, T; Kirby, E G

    1990-09-01

    Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) cell cultures sampled 3, 6, or 9 days after subculture in nutrient medium were able to survive subsequent subculture in a medium containing 15% polyethylene glycol (PEG) (M(r) 6000-8000) (-1.21 MPa), whereas cell sampled 12 or 16 days after subculture in nutrient medium became senescent when transferred to a medium containing 15% PEG. Cells sampled after subculture for 3, 6, or 9 days in nutrient medium had lower fresh weight/dry weight ratios, lower osmotic potentials, smaller cell diameters, and higher turgor pressures than cells sampled after 12 or 16 days subculture in nutrient medium. Cells surviving subculture to a medium containing 15% PEG did not increase in dry weight for 5 weeks even though the medium was exchanged every 7 days. After 5 weeks, however, dry weight growth resumed and reached 75% of the level attained by control cells grown on PEG-free medium. Long-term growth on a medium containing 15% PEG (PEG-selected cells) could only be sustained if the medium was supplemented with 30 mM glutamine. The PEG-selected cells grew in small clusters, were isodiametric, and had chlorophyll contents 50% higher than unselected cells. The PEG-selected cells also showed lowered cellular osmotic potentials, presumably due to osmoregulation. Turgor pressures of PEG-selected cells were greater than or equal to those of unselected cells.

  2. Use of backscattered electron imaging, X-ray microanalysis and X-ray microscopy in demonstrating physiological cell death

    International Nuclear Information System (INIS)

    Bowen, I.D.; Worrill, N.A.; Winters, C.A.; Mullarkey, K.

    1988-01-01

    The cytochemical localization of enzymatic activity by means of backscattered electron imaging (BEI) is reviewed and the application of BEI to changes in acid phosphatase and ATPase distribution during physiological (programmed) cell death in Heliothis midgut is explored. Programmed cell death entails the release of nascent free acid phosphatase as extracisternal hydrolase. This shift can readily be detected by means of the atomic number contrast imparted by BEI of the lead phosphatase reaction product, thus enabling the distribution of dying cells to be mapped. BEI is particularly useful in this context as it allows the examination of bulk specimens at low magnification. Death of cells is also accompanied by a collapse in ATPase activity which shows up as cytochemically negative areas in the X-ray microscope and by means of BEI. Acid phosphatase in normal cells is localized in the apical microvilli and lysosomes. Senescent or dying cells, however, clearly show a basally situated free hydrolase which migrates throughout the cell. Parallel TEM results confirm that this enzyme is ribosomal and extracisternal rather than lysosomal in origin. ATPase activity is largely limited to the apical microvilli, although there is some activity associated with the basal plasma membranes. The apical ATPase, however is partially resistant to ouabain. Young and mature cells are positive although in the latter case some microvilli may be lost as the cells acquire a negative cap or dome. Inhibition by bromotetramizole indicates that apical activity is not to any significant extent contributed to by alkaline phosphatase. Degenerate or dead cells are negative and can be seen as a mozaic of black patches among normal cells when imaged by means of BEI or X-ray microscopy

  3. Physiological responses of wild type and putrescine-overproducing transgenic cells of poplar to variations in the form and concentration of nitrogen in the medium

    Science.gov (United States)

    Rakesh Minocha; Jae Soon Lee; Stephanie Long; Pratiksha Bhatnagar; Subhash C. Minocha

    2004-01-01

    We determined: (a) the physiological consequences of overproduction of putrescine in transgenic poplar (Populus nigra x mnrimoviczir) cells expressing an omithine decarboxylase transgene; and (b) effects of variation in nitrogen (N) concentration of the medium on cellular polyamine concentration in transgenic and non-transgenic cells. Cells grown in...

  4. Expression and proliferation profiles of PKC, JNK and p38MAPK in physiologically stretched human bladder smooth muscle cells

    International Nuclear Information System (INIS)

    Wazir, Romel; Luo, De-Yi; Dai, Yi; Yue, Xuan; Tian, Ye; Wang, Kun-Jie

    2013-01-01

    Highlights: •Stretch induces proliferation in human bladder smooth muscle cells (HBSMC). •5% Equibiaxial elongation produces maximum proliferation. •Physiologic stretch decreases apoptotic cell death. •PKC is involved in functional modulation of bladder. •JNK and p38 are not involved in proliferating HBSMC. -- Abstract: Objective: To determine protein kinase C (PKC), c-Jun NH2-Terminal Kinase (JNK) and P38 mitogen-activated protein kinases (p38MAPK) expression levels and effects of their respective inhibitors on proliferation of human bladder smooth muscle cells (HBSMCs) when physiologically stretched in vitro. Materials and methods: HBSMCs were grown on silicone membrane and stretch was applied under varying conditions; (equibiaxial elongation: 2.5%, 5%, 10%, 15%, 20%, 25%), (frequency: 0.05, 0.1, 0.2, 0.5, 1 Hz). Optimal physiological stretch was established by assessing proliferation with 5-Bromo-2-deoxyuridine (BrdU) assay and flow cytometry. PKC, JNK and p38 expression levels were analyzed by Western blot. Specificity was maintained by employing specific inhibitors; (GF109203X for PKC, SP600125 for JNK and SB203580 for p38MAPK), in some experiments. Results: Optimum proliferation was observed at 5% equibiaxial stretch (BrdU: 0.837 ± 0.026 (control) to 1.462 ± 0.023)%, (P 0.05 SP600125) and (1.461 ± 0.01, P > 0.05 SB203580). These findings show that mechanical stretch can promote magnitude-dependent proliferative modulation through PKC and possibly JNK but not via p38MAPK in hBSMCs

  5. RODENT LEYDIG CELL TUMORIGENESIS: A REVIEW OF THE PHYSIOLOGY, PATHOLOGY, MECHANISMS, AND RELEVANCE TO HUMANS

    Science.gov (United States)

    Leydig cells (LCs) are the cells of the testis that have as their primary function the production of testosterone. LCs are a common target of compounds tested in rodent carcinogenicity bioassays. The number of reviews on Leydig cell tumors (LCTs) has increased in recent years bec...

  6. Nano- and microstructured materials for in vitro studies of the physiology of vascular cells

    Directory of Open Access Journals (Sweden)

    Alexandra M. Greiner

    2016-11-01

    Full Text Available The extracellular environment of vascular cells in vivo is complex in its chemical composition, physical properties, and architecture. Consequently, it has been a great challenge to study vascular cell responses in vitro, either to understand their interaction with their native environment or to investigate their interaction with artificial structures such as implant surfaces. New procedures and techniques from materials science to fabricate bio-scaffolds and surfaces have enabled novel studies of vascular cell responses under well-defined, controllable culture conditions. These advancements are paving the way for a deeper understanding of vascular cell biology and materials–cell interaction. Here, we review previous work focusing on the interaction of vascular smooth muscle cells (SMCs and endothelial cells (ECs with materials having micro- and nanostructured surfaces. We summarize fabrication techniques for surface topographies, materials, geometries, biochemical functionalization, and mechanical properties of such materials. Furthermore, various studies on vascular cell behavior and their biological responses to micro- and nanostructured surfaces are reviewed. Emphasis is given to studies of cell morphology and motility, cell proliferation, the cytoskeleton and cell-matrix adhesions, and signal transduction pathways of vascular cells. We finalize with a short outlook on potential interesting future studies.

  7. Crystallization phenomena in slags

    Science.gov (United States)

    Orrling, Carl Folke

    2000-09-01

    The crystallization of the mold slag affects both the heat transfer and the lubrication between the mold and the strand in continuous casting of steel. In order for mold slag design to become an engineering science rather than an empirical exercise, a fundamental understanding of the melting and solidification behavior of a slag must be developed. Thus it is necessary to be able to quantify the phenomena that occur under the thermal conditions that are found in the mold of a continuous caster. The double hot thermocouple technique (DHTT) and the Confocal Laser Scanning Microscope used in this study are two novel techniques for investigating melting and solidification phenomena of transparent slags. Results from these techniques are useful in defining the phenomena that occur when the slag film infiltrates between the mold and the shell of the casting. TTT diagrams were obtained for various slags and indicated that the onset of crystallization is a function of cooling rate and slag chemistry. Crystal morphology was found to be dependent upon the experimental temperature and four different morphologies were classified based upon the degree of melt undercooling. Continuous cooling experiments were carried out to develop CCT diagrams and it was found that the amount and appearance of the crystalline fraction greatly depends on the cooling conditions. The DHTT can also be used to mimic the cooling profile encountered by the slag in the mold of a continuous caster. In this differential cooling mode (DCT), it was found that the details of the cooling rate determine the actual response of the slag to a thermal gradient and small changes can lead to significantly different results. Crystal growth rates were measured and found to be in the range between 0.11 mum/s to 11.73 mum/s depending on temperature and slag chemistry. Alumina particles were found to be effective innoculants in oxide melts reducing the incubation time for the onset of crystallization and also extending

  8. The barley anion channel, HvALMT1, has multiple roles in guard cell physiology and grain metabolism.

    Science.gov (United States)

    Xu, Muyun; Gruber, Benjamin D; Delhaize, Emmanuel; White, Rosemary G; James, Richard A; You, Jiangfeng; Yang, Zhenming; Ryan, Peter R

    2015-01-01

    The barley (Hordeum vulgare) gene HvALMT1 encodes an anion channel in guard cells and in certain root tissues indicating that it may perform multiple roles. The protein localizes to the plasma membrane and facilitates malate efflux from cells when constitutively expressed in barley plants and Xenopus oocytes. This study investigated the function of HvALMT1 further by identifying its tissue-specific expression and by generating and characterizing RNAi lines with reduced HvALMT1 expression. We show that transgenic plants with 18-30% of wild-type HvALMT1 expression had impaired guard cell function. They maintained higher stomatal conductance in low light intensity and lost water more rapidly from excised leaves than the null segregant control plants. Tissue-specific expression of HvALMT1 was investigated in developing grain and during germination using transgenic barley lines expressing the green fluorescent protein (GFP) with the HvALMT1 promoter. We found that HvALMT1 is expressed in the nucellar projection, the aleurone layer and the scutellum of developing barley grain. Malate release measured from isolated aleurone layers prepared from imbibed grain was significantly lower in the RNAi barley plants compared with control plants. These data provide molecular and physiological evidence that HvALMT1 functions in guard cells, in grain development and during germination. We propose that HvALMT1 releases malate and perhaps other anions from guard cells to promote stomatal closure. The likely roles of HvALMT1 during seed development and grain germination are also discussed. © 2014 Scandinavian Plant Physiology Society.

  9. Perspectives for induced pluripotent stem cell technology: new insights into human physiology involved in somatic mosaicism.

    Science.gov (United States)

    Nagata, Naoki; Yamanaka, Shinya

    2014-01-31

    Induced pluripotent stem cell technology makes in vitro reprogramming of somatic cells from individuals with various genetic backgrounds possible. By applying this technology, it is possible to produce pluripotent stem cells from biopsy samples of arbitrarily selected individuals with various genetic backgrounds and to subsequently maintain, expand, and stock these cells. From these induced pluripotent stem cells, target cells and tissues can be generated after certain differentiation processes. These target cells/tissues are expected to be useful in regenerative medicine, disease modeling, drug screening, toxicology testing, and proof-of-concept studies in drug development. Therefore, the number of publications concerning induced pluripotent stem cells has recently been increasing rapidly, demonstrating that this technology has begun to infiltrate many aspects of stem cell biology and medical applications. In this review, we discuss the perspectives of induced pluripotent stem cell technology for modeling human diseases. In particular, we focus on the cloning event occurring through the reprogramming process and its ability to let us analyze the development of complex disease-harboring somatic mosaicism.

  10. Workshop on Interface Phenomena

    CERN Document Server

    Kreuzer, Hans

    1987-01-01

    This book contains the proceedings of the first Workshop on Interface Phenomena, organized jointly by the surface science groups at Dalhousie University and the University of Maine. It was our intention to concentrate on just three topics related to the kinetics of interface reactions which, in our opinion, were frequently obscured unnecessarily in the literature and whose fundamental nature warranted an extensive discussion to help clarify the issues, very much in the spirit of the Discussions of the Faraday Society. Each session (day) saw two principal speakers expounding the different views; the session chairmen were asked to summarize the ensuing discussions. To understand the complexity of interface reactions, paradigms must be formulated to provide a framework for the interpretation of experimen­ tal data and for the construction of theoretical models. Phenomenological approaches have been based on a small number of rate equations for the concentrations or mole numbers of the various species involved i...

  11. The Effects of Orbital Spaceflight on Human Osteoblastic Cell Physiology and Gene Expression

    Science.gov (United States)

    Turner, R. T.

    1999-01-01

    The purpose of the proposed study is to establish whether changes in gravitational loading have a direct effect on osteoblasts to regulate TGF-6 expression. The effects of spaceflight and reloading on TGF-B MRNA and peptide levels will be studied in a newly developed line of immortalized human fetal osteoblasts (HFOB) transfected with an SV-40 temperature dependent mutant to generate proliferating, undifferentiated hFOB cells at 33-34 C and a non-proliferating, differentiated HFOB cells at 37-39'C. Unlike previous cell culture models, HFOB cells have unlimited proliferative capacity yet can be precisely regulated to differentiate into mature cells which express mature osteoblast function. If isolated osteoblasts respond to changes in mechanical loading in a manner similar to their response in animals, the cell system could provide a powerful model to investigate the signal transduction pathway for gravitational loading.

  12. Detection and antibiotic treatment of Mycoplasma arginini contamination in a mouse epithelial cell line restore normal cell physiology.

    Science.gov (United States)

    Boslett, Brianna; Nag, Subhra; Resnick, Andrew

    2014-01-01

    Mycoplasma contamination of cultured cell lines is difficult to detect by routine observation. Infected cells can display normal morphology and the slow growth rate of mycoplasma can delay detection for extended periods of time, compromising experimental results. Positive identification of mycoplasma typically requires cells to be either fixed and stained for DNA or processed with PCR. We present a method to detect mycoplasma using live-cell optical microscopy typically used for routine observation of cell cultures. Images of untreated mycoplasma-infected epithelial cells alongside images of infected cells treated with Plasmocin, a commercially available antibiotic targeted to mycoplasma, are shown. We found that optical imaging is an effective screening tool for detection of mycoplasma contamination. Importantly, we found that cells regained normal function after the contamination was cleared. In conclusion, we present a technique to diagnose probable mycoplasma infections in live cultures without fixation, resulting in faster response times and decreased loss of cell material.

  13. Detection and Antibiotic Treatment of Mycoplasma arginini Contamination in a Mouse Epithelial Cell Line Restore Normal Cell Physiology

    Directory of Open Access Journals (Sweden)

    Brianna Boslett

    2014-01-01

    Full Text Available Mycoplasma contamination of cultured cell lines is difficult to detect by routine observation. Infected cells can display normal morphology and the slow growth rate of mycoplasma can delay detection for extended periods of time, compromising experimental results. Positive identification of mycoplasma typically requires cells to be either fixed and stained for DNA or processed with PCR. We present a method to detect mycoplasma using live-cell optical microscopy typically used for routine observation of cell cultures. Images of untreated mycoplasma-infected epithelial cells alongside images of infected cells treated with Plasmocin, a commercially available antibiotic targeted to mycoplasma, are shown. We found that optical imaging is an effective screening tool for detection of mycoplasma contamination. Importantly, we found that cells regained normal function after the contamination was cleared. In conclusion, we present a technique to diagnose probable mycoplasma infections in live cultures without fixation, resulting in faster response times and decreased loss of cell material.

  14. NKT cell subsets as key participants in liver physiology and pathology.

    Science.gov (United States)

    Bandyopadhyay, Keya; Marrero, Idania; Kumar, Vipin

    2016-05-01

    Natural killer T (NKT) cells are innate-like lymphocytes that generally recognize lipid antigens and are enriched in microvascular compartments of the liver. NKT cells can be activated by self- or microbial-lipid antigens and by signaling through toll-like receptors. Following activation, NKT cells rapidly secrete pro-inflammatory or anti-inflammatory cytokines and chemokines, and thereby determine the milieu for subsequent immunity or tolerance. It is becoming clear that two different subsets of NKT cells-type I and type II-have different modes of antigen recognition and have opposing roles in inflammatory liver diseases. Here we focus mainly on the roles of both NKT cell subsets in the maintenance of immune tolerance and inflammatory diseases in liver. Furthermore, how the differential activation of type I and type II NKT cells influences other innate cells and adaptive immune cells to result in important consequences for tissue integrity is discussed. It is crucial that better reagents, including CD1d tetramers, be used in clinical studies to define the roles of NKT cells in liver diseases in patients.

  15. The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

    Directory of Open Access Journals (Sweden)

    Farhad Dehkhoda

    2018-02-01

    Full Text Available The growth hormone receptor (GHR, although most well known for regulating growth, has many other important biological functions including regulating metabolism and controlling physiological processes related to the hepatobiliary, cardiovascular, renal, gastrointestinal, and reproductive systems. In addition, growth hormone signaling is an important regulator of aging and plays a significant role in cancer development. Growth hormone activates the Janus kinase (JAK–signal transducer and activator of transcription (STAT signaling pathway, and recent studies have provided a new understanding of the mechanism of JAK2 activation by growth hormone binding to its receptor. JAK2 activation is required for growth hormone-mediated activation of STAT1, STAT3, and STAT5, and the negative regulation of JAK–STAT signaling comprises an important step in the control of this signaling pathway. The GHR also activates the Src family kinase signaling pathway independent of JAK2. This review covers the molecular mechanisms of GHR activation and signal transduction as well as the physiological consequences of growth hormone signaling.

  16. The interactive effects of multiple stressors on physiological stress responses and club cell investment in fathead minnows

    Energy Technology Data Exchange (ETDEWEB)

    Manek, Aditya K., E-mail: aditya.manek@usask.ca [Department of Biology, University of Saskatchewan, Saskatoon, S7N 5E2 SK (Canada); Ferrari, Maud C.O. [Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK S7N 5B4 (Canada); Niyogi, Som; Chivers, Douglas P. [Department of Biology, University of Saskatchewan, Saskatoon, S7N 5E2 SK (Canada)

    2014-04-01

    Anthropogenic activities have dramatically increased over the past decades, with the consequence that many organisms are simultaneously exposed to multiple stressors. Understanding how organisms respond to these stressors is a key focus for scientists from many disciplines. Here we investigated the interactive effects of two stressors, UV radiation (UVR) and cadmium (Cd) exposure on a common freshwater fish, fathead minnow (Pimephales promelas). UVR is known to influence the density of epidermal club cells (ECCs), which are not only a key component of the innate immune system of fishes, but are also the source of chemical alarm cues that serve to warn other fishes of nearby predators. In contrast, Cd impairs the physiological stress response and ability of fish to respond to alarm cues. We used an integrative approach to examine physiological stress response as well as investment in ECCs. Fish exposed to UVR had higher levels of cortisol than non-exposed controls, but Cd reduced cortisol levels substantially for fish exposed to UVR. Fish exposed to UVR, either in the presence or absence of Cd, showed consistent decreases in ECC investment compared to non-exposed controls. Despite differences in ECC number, there was no difference in the potency of alarm cues prepared from the skin of UVR and Cd exposed or non-exposed fish indicating that UVR and Cd exposure combined may have little influence on chemically-mediated predator–prey interactions. - Highlights: • UV radiation caused a physiological stress response (cortisol release) in fish. • Cd reduced cortisol levels substantially for fish exposed to UV. • Fish exposed to UV, with or without Cd, showed decreases in club cell investment. • There was no difference in alarm cues potency from UV and Cd exposed fish. • Our work highlights the difficulty of untangling effects of multiple stressors.

  17. Gene expression profiling of pituitary melanotrope cells during their physiological activation.

    NARCIS (Netherlands)

    Kuribara, M.; Bakel, N.H. van; Ramekers, D.; Gouw, D. de; Neijts, R.; Roubos, E.W.; Scheenen, W.J.; Martens, G.J.M.; Jenks, B.G.

    2012-01-01

    The pituitary melanotrope cells of the amphibian Xenopus laevis are responsible for the production of the pigment-dispersing peptide alpha-melanophore-stimulating hormone, which allows the animal to adapt its skin color to its environment. During adaptation to a dark background the melanotrope cells

  18. Physiology and Endocrinology Symposium: role of immune cells in the corpus luteum.

    Science.gov (United States)

    Walusimbi, S S; Pate, J L

    2013-04-01

    The immune system is essential for optimal function of the reproductive system. The corpus luteum (CL) is an endocrine organ that secretes progesterone, which is responsible for regulating the length of the estrous cycle, and for the establishment and maintenance of pregnancy in mammals. This paper reviews literature that addresses 2 areas; i) how immune cells are recruited to the CL, and ii) how immune cells communicate with luteal cells to affect the formation, development, and regression of the CL. Immune cells, primarily recruited to the ovulatory follicle from lymphoid organs after the LH surge, facilitate ovulation and populate the developing CL. During the luteal phase, changes in the population of macrophages, eosinophils, neutrophils, and T lymphocytes occur at critical functional stages of the CL. In addition to their role in facilitating ovulation, immune cells may have an important role in luteal function. Evidence shows that cytokines secreted by immune cells modulate both luteotropic and luteolytic processes. However, the decision to pursue either function may depend on the environment provided by luteal cells. It is suggested that understanding the role immune cells play could lead to identification of new strategies to improve fertility in dairy cattle and other species.

  19. NKT cell subsets as key participants in liver physiology and pathology

    Science.gov (United States)

    Bandyopadhyay, Keya; Marrero, Idania; Kumar, Vipin

    2016-01-01

    Natural killer T (NKT) cells are innate-like lymphocytes that generally recognize lipid antigens and are enriched in microvascular compartments of the liver. NKT cells can be activated by self- or microbial-lipid antigens and by signaling through toll-like receptors. Following activation, NKT cells rapidly secrete pro-inflammatory or anti-inflammatory cytokines and chemokines, and thereby determine the milieu for subsequent immunity or tolerance. It is becoming clear that two different subsets of NKT cells—type I and type II—have different modes of antigen recognition and have opposing roles in inflammatory liver diseases. Here we focus mainly on the roles of both NKT cell subsets in the maintenance of immune tolerance and inflammatory diseases in liver. Furthermore, how the differential activation of type I and type II NKT cells influences other innate cells and adaptive immune cells to result in important consequences for tissue integrity is discussed. It is crucial that better reagents, including CD1d tetramers, be used in clinical studies to define the roles of NKT cells in liver diseases in patients. PMID:26972772

  20. Microfluidic device to study cell transmigration under physiological shear stress conditions

    DEFF Research Database (Denmark)

    Kwasny, Dorota; Kiilerich-Pedersen, Katrine; Moresco, Jacob Lange

    2011-01-01

    The development of new drug therapies relies on studies of cell transmigration in in vitro systems. Migration has traditionally been studied using two methods, the Boyden chamber and a shear flow chamber assay. Though, commonly applied in cell transmigration studies, they are far from imitating a...

  1. Detection and Antibiotic Treatment of Mycoplasma arginini Contamination in a Mouse Epithelial Cell Line Restore Normal Cell Physiology

    OpenAIRE

    Boslett, Brianna; Nag, Subhra; Resnick, Andrew

    2014-01-01

    Mycoplasma contamination of cultured cell lines is difficult to detect by routine observation. Infected cells can display normal morphology and the slow growth rate of mycoplasma can delay detection for extended periods of time, compromising experimental results. Positive identification of mycoplasma typically requires cells to be either fixed and stained for DNA or processed with PCR. We present a method to detect mycoplasma using live-cell optical microscopy typically used for routine obser...

  2. Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog (Rana catesbeiana).

    Science.gov (United States)

    Azimzadeh, Julien B; Salvi, Joshua D

    2017-03-17

    The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American bullfrog, has become a mainstay of auditory and vestibular research. Studies of this organ have revealed how sensory cells hair can actively detect signals from the environment. Because of these studies, we now better understand the mechanical gating and localization of a hair cell's transduction channels, calcium's role in mechanical adaptation, and the identity of hair cell currents. This highly accessible organ continues to provide insight into the workings of hair cells. Here we describe the preparation of the bullfrog's sacculus for biophysical studies on its hair cells. We include the complete dissection procedure and provide specific protocols for the preparation of the sacculus in specific contexts. We additionally include representative results using this preparation, including the calculation of a hair bundle's instantaneous force-displacement relation and measurement of a bundle's spontaneous oscillation.

  3. Exosomes bind to autotaxin and act as a physiological delivery mechanism to stimulate LPA receptor signalling in cells

    Science.gov (United States)

    Jethwa, Susanna A.; Leah, Emma J.; Zhang, Qifeng; Bright, Nicholas A.; Oxley, David; Bootman, Martin D.; Rudge, Simon A.

    2016-01-01

    ABSTRACT Autotaxin (ATX; also known as ENPP2), the lysophospholipase responsible for generating the lipid receptor agonist lysophosphatidic acid (LPA), is a secreted enzyme. Here we show that, once secreted, ATX can bind to the surface of cell-secreted exosomes. Exosome-bound ATX is catalytically active and carries generated LPA. Once bound to a cell, through specific integrin interactions, ATX releases the LPA to activate cell surface G-protein-coupled receptors of LPA; inhibition of signalling by the receptor antagonist Ki1642 suggests that these receptors are LPAR1 and LPAR3. The binding stimulates downstream signalling, including phosphorylation of AKT and mitogen-activated protein kinases, the release of intracellular stored Ca2+ and cell migration. We propose that exosomal binding of LPA-loaded ATX provides a means of efficiently delivering the lipid agonist to cell surface receptors to promote signalling. We further propose that this is a means by which ATX–LPA signalling operates physiologically. PMID:27557622

  4. Electrodiffusion phenomena in neuroscience: a neglected companion.

    Science.gov (United States)

    Savtchenko, Leonid P; Poo, Mu Ming; Rusakov, Dmitri A

    2017-09-19

    The emerging technological revolution in genetically encoded molecular sensors and super-resolution imaging provides neuroscientists with a pass to the real-time nano-world. On this small scale, however, classical principles of electrophysiology do not always apply. This is in large part because the nanoscopic heterogeneities in ionic concentrations and the local electric fields associated with individual ions and their movement can no longer be ignored. Here, we review basic principles of molecular electrodiffusion in the cellular environment of organized brain tissue. We argue that accurate interpretation of physiological observations on the nanoscale requires a better understanding of the underlying electrodiffusion phenomena.

  5. Expression and proliferation profiles of PKC, JNK and p38MAPK in physiologically stretched human bladder smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Wazir, Romel; Luo, De-Yi; Dai, Yi; Yue, Xuan; Tian, Ye; Wang, Kun-Jie, E-mail: kunjiewangatscu@163.com

    2013-08-30

    Highlights: •Stretch induces proliferation in human bladder smooth muscle cells (HBSMC). •5% Equibiaxial elongation produces maximum proliferation. •Physiologic stretch decreases apoptotic cell death. •PKC is involved in functional modulation of bladder. •JNK and p38 are not involved in proliferating HBSMC. -- Abstract: Objective: To determine protein kinase C (PKC), c-Jun NH2-Terminal Kinase (JNK) and P38 mitogen-activated protein kinases (p38MAPK) expression levels and effects of their respective inhibitors on proliferation of human bladder smooth muscle cells (HBSMCs) when physiologically stretched in vitro. Materials and methods: HBSMCs were grown on silicone membrane and stretch was applied under varying conditions; (equibiaxial elongation: 2.5%, 5%, 10%, 15%, 20%, 25%), (frequency: 0.05, 0.1, 0.2, 0.5, 1 Hz). Optimal physiological stretch was established by assessing proliferation with 5-Bromo-2-deoxyuridine (BrdU) assay and flow cytometry. PKC, JNK and p38 expression levels were analyzed by Western blot. Specificity was maintained by employing specific inhibitors; (GF109203X for PKC, SP600125 for JNK and SB203580 for p38MAPK), in some experiments. Results: Optimum proliferation was observed at 5% equibiaxial stretch (BrdU: 0.837 ± 0.026 (control) to 1.462 ± 0.023)%, (P < 0.05) and apoptotic cell death rate decreased from 16.4 ± 0.21% (control) to 4.5 ± 0.13% (P < 0.05) applied at 0.1 Hz. Expression of PKC was upregulated with slight increase in JNK and no change in p38MAPK after application of stretch. Inhibition had effects on proliferation (1.075 ± 0.024, P < 0.05 GF109203X); (1.418 ± 0.021, P > 0.05 SP600125) and (1.461 ± 0.01, P > 0.05 SB203580). These findings show that mechanical stretch can promote magnitude-dependent proliferative modulation through PKC and possibly JNK but not via p38MAPK in hBSMCs.

  6. Grasping the nature of the cell interior: from Physiological Chemistry to Chemical Biology.

    Science.gov (United States)

    Kyne, Ciara; Crowley, Peter B

    2016-08-01

    Current models of the cell interior emphasise its crowded, chemically complex and dynamically organised structure. Although the chemical composition of cells is known, the cooperative intermolecular interactions that govern cell ultrastructure are poorly understood. A major goal of biochemistry is to capture these myriad interactions in vivo. We consider the landmark discoveries that have shaped this objective, starting from the vitalist framework established by early natural philosophers. Through this historical revisionism, we extract important lessons for the bioinspired chemists of today. Scientific specialisation tends to insulate seminal ideas and hamper the unification of paradigms across biology. Therefore, we call for interdisciplinary collaboration in grappling with the complex cell interior. Recent successes in integrative structural biology and chemical biology demonstrate the power of hybrid approaches. The future roles of the (bio)chemist and model systems are also discussed as starting points for in vivo explorations. © 2016 Federation of European Biochemical Societies.

  7. Physiological and pharmacological properties of Purkinje cells in rat cerebellum degranulated by postnatal x irradiation

    International Nuclear Information System (INIS)

    Woodward, D.J.; Hoffer, B.J.; Altman, J.

    1974-01-01

    Elimination of most granule, basket, and stellate interneurons in the rat cerebellum was achieved by repeated doses of low level x irradiation applied during the first two weeks of postnatal life. Purkinje neurons in these rats, studied when adults, exhibited sustained spiking activity in Halothane anesthetized preparations. Mean firing rates were 35 to 40/sec, no different from normal. Spontaneous bursts presumed to be generated by climbing fiber synaptic activity differed from normal by often consisting of full sized spikes rather than characteristic inactivation responses. Intracellularly observed correlates of bursts consisted of epsp's of several discretely different amplitudes appearing independently in time. Stimulation of white matter revealed evidence for, a) graded synaptic excitation of Purkinje cells indicating more than one converging excitatory synapse, and b) inhibitory actions on Purkinje cells either through a few remaining inhibitory interneurons or through Purkinje cell recurrent collaterals. Iontophoretic drug application studies showed normal chemosensitivity of the Purkinje cell membrane, i.e., excitation by flutamate and inhibition by gamma-amino butyric acid, serotonin, norepinephrine, and 3'5' cyclic AMP. These studies indicate considerable autonomy of Purkinje cell ontogenesis in the absence of normal interneuronal input. A unique synaptic relation only rarely found in normal cerebellum is the innervation of single Purkinje cells by more than one climbing fiber. (U.S.)

  8. Nuclear fuel deformation phenomena

    International Nuclear Information System (INIS)

    Van Brutzel, L.; Dingreville, R.; Bartel, T.J.

    2015-01-01

    Nuclear fuel encounters severe thermomechanical environments. Its mechanical response is profoundly influenced by an underlying heterogeneous microstructure but also inherently dependent on the temperature and stress level histories. The ability to adequately simulate the response of such microstructures, to elucidate the associated macroscopic response in such extreme environments is crucial for predicting both performance and transient fuel mechanical responses. This chapter discusses key physical phenomena and the status of current modelling techniques to evaluate and predict fuel deformations: creep, swelling, cracking and pellet-clad interaction. This chapter only deals with nuclear fuel; deformations of cladding materials are discussed elsewhere. An obvious need for a multi-physics and multi-scale approach to develop a fundamental understanding of properties of complex nuclear fuel materials is presented. The development of such advanced multi-scale mechanistic frameworks should include either an explicit (domain decomposition, homogenisation, etc.) or implicit (scaling laws, hand-shaking,...) linkage between the different time and length scales involved, in order to accurately predict the fuel thermomechanical response for a wide range of operating conditions and fuel types (including Gen-IV and TRU). (authors)

  9. Acid Deposition Phenomena

    International Nuclear Information System (INIS)

    Ramadan, A.E.K.

    2004-01-01

    Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H 2 SO 4 ) and nitric acids (HNO 3 ), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry

  10. Differential mechanism of Escherichia coli Inactivation by (+)-limonene as a function of cell physiological state and drug's concentration.

    Science.gov (United States)

    Chueca, Beatriz; Pagán, Rafael; García-Gonzalo, Diego

    2014-01-01

    (+)-limonene is a lipophilic antimicrobial compound, extracted from citrus fruits' essential oils, that is used as a flavouring agent and organic solvent by the food industry. A recent study has proposed a common and controversial mechanism of cell death for bactericidal antibiotics, in which hydroxyl radicals ultimately inactivated cells. Our objective was to determine whether the mechanism of Escherichia coli MG1655 inactivation by (+)-limonene follows that of bactericidal antibiotics. A treatment with 2,000 μL/L (+)-limonene inactivated 4 log10 cycles of exponentially growing E. coli cells in 3 hours. On one hand, an increase of cell survival in the ΔacnB mutant (deficient in a TCA cycle enzyme), or in the presence of 2,2'-dipyridyl (inhibitor of Fenton reaction by iron chelation), thiourea, or cysteamine (hydroxyl radical scavengers) was observed. Moreover, the ΔrecA mutant (deficient in an enzyme involved in SOS response to DNA damage) was more sensitive to (+)-limonene. Thus, this indirect evidence indicates that the mechanism of exponentially growing E. coli cells inactivation by 2,000 μL/L (+)-limonene is due to the TCA cycle and Fenton-mediated hydroxyl radical formation that caused oxidative DNA damage, as observed for bactericidal drugs. However, several differences have been observed between the proposed mechanism for bactericidal drugs and for (+)-limonene. In this regard, our results demonstrated that E. coli inactivation was influenced by its physiological state and the drug's concentration: experiments with stationary-phase cells or 4,000 μL/L (+)-limonene uncovered a different mechanism of cell death, likely unrelated to hydroxyl radicals. Our research has also shown that drug's concentration is an important factor influencing the mechanism of bacterial inactivation by antibiotics, such as kanamycin. These results might help in improving and spreading the use of (+)-limonene as an antimicrobial compound, and in clarifying the controversy about

  11. Antibody-Directed Effector Cell Therapy of Tumors: Analysis and Optimization Using a Physiologically Based Pharmacokinetic Model

    Directory of Open Access Journals (Sweden)

    Stuart W. Friedrich

    2002-01-01

    Full Text Available The failure of the cellular immune response to stop solid tumor growth has been the subject of much research. Although the mechanisms for tumor evasion of immune response are poorly understood, one viable explanation is that tumor-killing lymphocytes cannot reach the tumor cells in sufficient quantity to keep the tumor in check. Recently, the use of bifunctional antibodies. (BFAs has been proposed as a way to direct immune cells to the tumor: one arm of the antibody is specific for a known tumor-associated antigen and the other for a lymphocyte marker such as CD3. Injecting this BFA should presumably result in cross-linking of lymphocytes. (either endogenous or adoptively transferred with tumor cells, thereby enhancing therapy. Results from such an approach, however, are often disappointing- frequently there is no benefit gained by using the BFA. We have analyzed the retargeting of endogenous effector cells by BFA using a physiologically based whole-body pharmacokinetic model that accounts for interactions between all relevant species in the various organs and tumor. Our results suggest that the design of the BFA is critical and the binding constants of the antigen and lymphocyte binding epitopes need to be optimized for successful therapy.

  12. Haters Phenomena in Social Media

    OpenAIRE

    Pradipta, Angga; Lailiyah, S.Sos, M.I.Kom, Nuriyatul

    2016-01-01

    Social media is internet-basic media, functioned as interaction media room based on multimedia technology. And social media created some effects. One of the negative effects of social media is haters phenomena. Haters are a person who easily said dirty words, harass, and humiliate to others. This phenomena causes anxiety—especially in Indonesia, even the Government issued public policy and letter of regulation about this phenomena, through Paragraph 27 verse (3) IT Constitution, Paragraph 45 ...

  13. Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

    International Nuclear Information System (INIS)

    Volland, Stefanie; Lütz, Cornelius; Michalke, Bernhard; Lütz-Meindl, Ursula

    2012-01-01

    Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 μM Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron–oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased

  14. Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

    Science.gov (United States)

    Volland, Stefanie; Lütz, Cornelius; Michalke, Bernhard; Lütz-Meindl, Ursula

    2012-01-01

    Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 μM Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron–oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased

  15. Transport phenomena in environmental engineering

    Science.gov (United States)

    Sander, Aleksandra; Kardum, Jasna Prlić; Matijašić, Gordana; Žižek, Krunoslav

    2018-01-01

    A term transport phenomena arises as a second paradigm at the end of 1950s with high awareness that there was a strong need to improve the scoping of chemical engineering science. At that point, engineers became highly aware that it is extremely important to take step forward from pure empirical description and the concept of unit operations only to understand the specific process using phenomenological equations that rely on three elementary physical processes: momentum, energy and mass transport. This conceptual evolution of chemical engineering was first presented with a well-known book of R. Byron Bird, Warren E. Stewart and Edwin N. Lightfoot, Transport Phenomena, published in 1960 [1]. What transport phenomena are included in environmental engineering? It is hard to divide those phenomena through different engineering disciplines. The core is the same but the focus changes. Intention of the authors here is to present the transport phenomena that are omnipresent in treatment of various process streams. The focus in this chapter is made on the transport phenomena that permanently occur in mechanical macroprocesses of sedimentation and filtration for separation in solid-liquid particulate systems and on the phenomena of the flow through a fixed and a fluidized bed of particles that are immanent in separation processes in packed columns and in environmental catalysis. The fundamental phenomena for each thermal and equilibrium separation process technology are presented as well. Understanding and mathematical description of underlying transport phenomena result in scoping the separation processes in a way that ChEs should act worldwide.

  16. The effect of space microgravity on the physiological activity of mammalian resident cardiac stem cells

    Science.gov (United States)

    Belostotskaya, Galina; Zakharov, Eugeny

    Prolonged exposure to weightlessness during space flights is known to cause depression of heart function in mammals. The decrease in heart weight and its remodeling under the influence of prolonged weightlessness (or space microgravity) is assumed to be due to both morphological changes of working cardiomyocytes and their progressive loss, as well as to possible depletion of resident cardiac stem cells (CSCs) population, or their inability to self-renewal and regeneration of muscle tissue under conditions of weightlessness. We have previously shown that the presence of different maturity clones formed by resident CSCs not only in culture but also in the mammalian myocardium can be used as an indicator of the regenerative activity of myocardial cells [Belostotskaya, et al., 2013: 2014]. In this study, we were interested to investigate whether the 30-day near-Earth space flight on the spacecraft BION-M1 affects the regenerative potential of resident CSCs. Immediately after landing of the spacecraft, we had examined the presence of resident c-kit+, Sca-1+ and Isl1+ CSCs and their development in suspension of freshly isolated myocardial cells of C57BL mice in comparison to controls. Cardiac cell suspension was obtained by enzymatic digestion of the heart [Belostotskaya and Golovanova, 2014]. Immunocytochemically stained preparations of fixed cells were analyzed with confocal microscope Leica TCS SP5 (Germany) in the Resource Center of St-Petersburg State University. CSCs were labeled with appropriate antibodies. CSCs differentiation into mature cardiomyocytes was verified using antibodies to Sarcomeric α-Actinin and Cardiac Troponin T. Antibodies to Connexin43 were used to detect cell-cell contacts. All antibodies were conjugated with Alexa fluorochromes (488, 532, 546, 568, 594 and/or 647 nm), according to Zenon-technology (Invitrogen). It has been shown that, under identical conditions of cell isolation, more complete digestion of heart muscle was observed in

  17. Ovarian Germline Stem Cells (OGSCs and the Hippo Signaling Pathway Association with Physiological and Pathological Ovarian Aging in Mice

    Directory of Open Access Journals (Sweden)

    Jia Li

    2015-07-01

    Full Text Available Background: The Hippo signaling pathway plays fundamental roles in stem cell maintenance in a variety of tissues and has thus implications for stem cell biology. Key components of this recently discovered pathway have been shown to be associated with primordial follicle activation. However, whether the Hippo signaling pathway plays a role in the development of Ovarian Germline Stem Cells (OGSCs during physiological and pathological ovarian aging in mice is unknown. Methods: Mice at the age of 7 days (7D, or of 2, 10, or 20 months (2M, 10M, 20M and mice at 2M treated with TPT and CY/BUS drugs were selected as physiological and pathological ovarian aging models, respectively. Immunohistochemistry was used to assess the development of follicles, and the co-localization of genes characteristic of OGSCs with MST1, LATS2 and YAP1 was assessed by immunofluorescence, western blotting and real-time PCR methods. Results: The Hippo signal pathway and MVH/OCT4 genes were co-expressed in the mouse ovarian cortex. The level and co-localization of LATS2, MST1, MVH, and OCT4 were significantly decreased with increased age, but YAP1 was more prevalent in the mouse ovarian cortex of 2M mice than 7D mice and was not observed in 20M mice. Furthermore, YAP1, MVH, and OCT4 were gradually decreased after TPT and CY/BUS treatment, and LATS2 mRNA and protein up-regulation persisted in TPT- and CY/BUS-treated mice. However, the expression of MST1 was lower in the TPT and CY/BUS groups compared with the control group. In addition, pYAP1 protein showed the highest expression in the ovarian cortexes of 7D mice compared with 20M mice, and the value of pYAP1/YAP1 decreased from 7D to 20M. Moreover, pYAP1 decreased in the TPT- and CY/BUS-treated groups, but the value of pYAP1/YAP1 increased in these groups. Conclusion: Taken together, our results show that the Hippo signaling pathway is associated with the changes that take place in OGSCs during physiological and pathological

  18. Terminology of allergic phenomena.

    Science.gov (United States)

    Ring, Johannes

    2014-01-01

    Over the last 2,000 years a variety of terms have been used for the description of phenomena possibly related to allergy. Many have been forgotten, while some of them have remained. In Greco-Roman literature the term 'idiosyncrasy' was used to describe an individual characterization of a health condition, possibly comparable to 'constitution'. The same term was also used to describe individual reaction patterns, and the term 'antipathy' was used in a similar sense. 'Hypersensitivity' originated from the German word 'Überempfindlichkeit' and was first used in a medical sense by Emil von Behring when he described untoward reactions to his antitoxin containing serum therapy. 'Anaphylaxis' was coined by Richet and Portier to describe the new phenomenon of a life-threatening general pathogenic reaction after repeated injection of antigen. In 1906, Clemens von Pirquet introduced the term 'allergy' in order to bring more clarity to the confusing debate regarding protective and harmful immunity. In order to characterize the familial occurrence of hypersensitivity reactions such as asthma, hay fever and others, the American allergists A.F. Coca and R.A. Cooke introduced the term 'atopy'. Contrary to anaphylaxis, which was experimentally induced, this type of 'hypersensitiveness' occurred spontaneously. The nature of the pathogenic factor was called the 'atopic reagin' and was found to be transferable with serum by Prausnitz and Küstner. After the detection of immunoglobulin (Ig) E as the carrier of this type of hypersensitivity, the term 'atopy' gained a new sense, since IgE is a characteristic - yet not exclusive - parameter of the so-called atopic diseases. Clinically similar diseases such as asthma, rhinoconjunctivitis or eczema can be found in the absence of IgE, and are then called 'intrinsic' variants of the same disease. © 2014 S. Karger AG, Basel.

  19. Dendritic cells in Leishmania major infections: mechanisms of parasite uptake, cell activation and evidence for physiological relevance.

    Science.gov (United States)

    Kautz-Neu, Kordula; Schwonberg, Kirsten; Fischer, Michael R; Schermann, Anja I; von Stebut, Esther

    2012-11-01

    Leishmaniasis is one of the most important infectious diseases worldwide; a vaccine is still not available. Infected dendritic cells (DC) are critical for the initiation of protective Th1 immunity against Leishmania major. Phagocytosis of L. major by DC leads to cell activation, IL-12 release and (cross-) presentation of Leishmania antigens by DC. Here, we review the role of Fcγ receptor- and B cell-mediated processes for parasite internalization by DC. In addition, the early events after parasite inoculation that consist of mast cell activation, parasite uptake by skin-resident macrophages (MΦ), followed by neutrophil and monocyte immigration and DC activation are described. All these events contribute significantly to antigen processing in infected DC and influence resulting T cell priming in vivo. A detailed understanding of the role of DC for the development of efficient anti-Leishmania immunity will aid the development of potent anti-parasite drugs and/or vaccines.

  20. Invited review: Pre- and postnatal adipose tissue development in farm animals: from stem cells to adipocyte physiology.

    Science.gov (United States)

    Louveau, I; Perruchot, M-H; Bonnet, M; Gondret, F

    2016-11-01

    Both white and brown adipose tissues are recognized to be differently involved in energy metabolism and are also able to secrete a variety of factors called adipokines that are involved in a wide range of physiological and metabolic functions. Brown adipose tissue is predominant around birth, except in pigs. Irrespective of species, white adipose tissue has a large capacity to expand postnatally and is able to adapt to a variety of factors. The aim of this review is to update the cellular and molecular mechanisms associated with pre- and postnatal adipose tissue development with a special focus on pigs and ruminants. In contrast to other tissues, the embryonic origin of adipose cells remains the subject of debate. Adipose cells arise from the recruitment of specific multipotent stem cells/progenitors named adipose tissue-derived stromal cells. Recent studies have highlighted the existence of a variety of those cells being able to differentiate into white, brown or brown-like/beige adipocytes. After commitment to the adipocyte lineage, progenitors undergo large changes in the expression of many genes involved in cell cycle arrest, lipid accumulation and secretory functions. Early nutrition can affect these processes during fetal and perinatal periods and can also influence or pre-determinate later growth of adipose tissue. How these changes may be related to adipose tissue functional maturity around birth and can influence newborn survival is discussed. Altogether, a better knowledge of fetal and postnatal adipose tissue development is important for various aspects of animal production, including neonatal survival, postnatal growth efficiency and health.

  1. Astrocyte-like glial cells physiologically regulate olfactory processing through the modification of ORN-PN synaptic strength in Drosophila.

    Science.gov (United States)

    Liu, He; Zhou, Bangyu; Yan, Wenjun; Lei, Zhengchang; Zhao, Xiaoliang; Zhang, Ke; Guo, Aike

    2014-09-01

    Astrocyte-like glial cells are abundant in the central nervous system of adult Drosophila and exhibit morphology similar to astrocytes of mammals. Previous evidence has shown that astrocyte-like glial cells are strongly associated with synapses in the antennal lobe (AL), the first relay of the olfactory system, where olfactory receptor neurons (ORNs) transmit information into projection neurons (PNs). However, the function of astrocyte-like glia in the AL remains obscure. In this study, using in vivo calcium imaging, we found that astrocyte-like glial cells exhibited spontaneous microdomain calcium elevations. Using simultaneous manipulation of glial activity and monitoring of neuronal function, we found that the astrocyte-like glial activation, but not ensheathing glial activation, could inhibit odor-evoked responses of PNs. Ensheathing glial cells are another subtype of glia, and are of functional importance in the AL. Electrophysiological experiments indicated that astrocyte-like glial activation decreased the amplitude and slope of excitatory postsynaptic potentials evoked through electrical stimulation of the antennal nerve. These results suggest that astrocyte-like glial cells may regulate olfactory processing through negative regulation of ORN-PN synaptic strength. Beyond the antennal lobe we observed astrocyte-like glial spontaneous calcium activities in the ventromedial protocerebrum, indicating that astrocyte-like glial spontaneous calcium elevations might be general in the adult fly brain. Overall, our study demonstrates a new function for astrocyte-like glial cells in the physiological modulation of olfactory information transmission, possibly through regulating ORN-PN synapse strength. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  2. Pro-apoptotic BIM is an essential initiator of physiological endothelial cell death independent of regulation by FOXO3.

    Science.gov (United States)

    Koenig, M N; Naik, E; Rohrbeck, L; Herold, M J; Trounson, E; Bouillet, P; Thomas, T; Voss, A K; Strasser, A; Coultas, L

    2014-11-01

    The growth of new blood vessels by angiogenesis is essential for normal development, but can also cause or contribute to the pathology of numerous diseases. Recent studies have shown that BIM, a pro-apoptotic BCL2-family protein, is required for endothelial cell apoptosis in vivo, and can contribute to the anti-angiogenic effect of VEGF-A inhibitors in certain tumor models. Despite its importance, the extent to which BIM is autonomously required for physiological endothelial apoptosis remains unknown and its regulation under such conditions is poorly defined. While the transcription factor FOXO3 has been proposed to induce Bim in response to growth factor withdrawal, evidence for this function is circumstantial. We report that apoptosis was reduced in Bim(-/-) primary endothelial cells, demonstrating a cell-autonomous role for BIM in endothelial death following serum and growth factor withdrawal. In conflict with in vitro studies, BIM-dependent endothelial death in vivo did not require FOXO3. Moreover, endothelial apoptosis proceeded normally in mice lacking FOXO-binding sites in the Bim promoter. Bim mRNA was upregulated in endothelial cells starved of serum and growth factors and this was accompanied by the downregulation of miRNAs of the miR-17∼92 cluster. Bim mRNA levels were also elevated in miR-17∼92(+/-) endothelial cells cultured under steady-state conditions, suggesting that miR-17∼92 cluster miRNAs may contribute to regulating overall Bim mRNA levels in endothelial cells.

  3. New Insight Into the Roles of Membrane Microdomains in Physiological Activities of Fungal Cells.

    Czech Academy of Sciences Publication Activity Database

    Malínský, Jan; Opekarová, Miroslava

    2016-01-01

    Roč. 325, mar. (2016), s. 119-180 ISSN 1937-6448 R&D Projects: GA ČR(CZ) GA15-10641S Institutional support: RVO:68378041 Keywords : membrane microdomain * membrane structure * fungi * membrane contact sites Subject RIV: EA - Cell Biology Impact factor: 3.752, year: 2015

  4. Thyroid hormone transport into liver cells: its (patho)physiological significance

    NARCIS (Netherlands)

    M. de Jong (Marion)

    1993-01-01

    textabstractIn the experiments described in this thesis transmembrane transport of thyroid hormones into liver cells is investigated, in particular the regulatory role of this transport process in the bioavailability of thyroid hormones in (patho )fysiological conditions. This first chapter is an

  5. Physiology of Ca2+ signalling in stem cells of different origins and differentiation stages

    Czech Academy of Sciences Publication Activity Database

    Forostyak, O.; Forostyak, S.; Kortus, Štěpán; Syková, E.; Verkhratsky, A.; Dayanithi, G.

    2016-01-01

    Roč. 59, 2-3 (2016), s. 57-66 ISSN 0143-4160 R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : stem cells * Ca2+ channels * Ca2+ signalling * spontaneous Ca2+ oscillations Subject RIV: FH - Neurology Impact factor: 3.707, year: 2016

  6. Abstracts of Review Articles and Educational Materials in Physiology

    Science.gov (United States)

    Physiology Teacher, 1977

    1977-01-01

    Contained are 99 abstracts of review articles, texts, books, manuals, learning programs, and audiovisual material used in teaching physiology. Specific fields include cell physiology, circulation, comparative physiology, development and aging, endocrinology and metabolism, environmental and exercise physiology, gastrointestinal physiology, muscle…

  7. Horning cell self-digestion: Autophagy wins the 2016 Nobel Prize in Physiology or Medicine

    Directory of Open Access Journals (Sweden)

    Po-Yuan Ke

    2017-02-01

    Full Text Available Autophagy is an evolutionarily conserved process by which eukaryotic cells eliminate intracellular components via the lysosomal degradation process. This cell self-digestion process was first discovered and morphologically characterized in the late 1950s and early 1960s. The genetic screen studies in baker's yeast in the 1990s further identified the essential genes functioning in the autophagic process. In the past two decades, the detailed molecular process involved in the completion of autophagy was delineated. Additionally, autophagy has been implied to function in many aspects of biological processes, including maintenance of organelle integrity, protein quality control, regulation of the stress response, and immunity. In addition to maintain cell homeostasis, autophagy has recently been shown to be modulated and to participate in the pathogenesis of human diseases, such as pathogen infections, neurodegenerative diseases, and tumor development. Overall, the breakthrough in autophagy research relies on the discovery of autophagy-related genes (ATGs using a genetic screening approach in Saccharomyces cerevisiae, which was established by Yoshinori Ohsumi. This year the Nobel Committee has awarded Yoshinori Ohsumi the Nobel Prize in Physiology or Medicine for his remarkable contribution to autophagy research.

  8. Physiologic Levels of Endogenous Hydrogen Sulfide Maintain the Proliferation and Differentiation Capacity of Periodontal Ligament Stem Cells.

    Science.gov (United States)

    Su, Yingying; Liu, Dayong; Liu, Yi; Zhang, Chunmei; Wang, Jinsong; Wang, Songlin

    2015-11-01

    Many invading oral bacteria are known to produce considerable amounts of hydrogen sulfide (H2S). The toxic activity of exogenous H2S in periodontal tissue has been demonstrated, but the role of endogenous H2S in the physiologic function of periodontal tissue remains poorly understood. The purpose of the present study is to investigate the biologic functions of H2S in the proliferation and differentiation of human periodontal ligament stem cells (PDLSCs). PDLSCs were isolated from periodontal ligament tissues of periodontally healthy volunteers or patients with periodontitis. Immunocytochemical staining, flow cytometry, and Western blot analysis were used to examine the expression of H2S-synthesizing enzymes cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). The proliferation capacity of PDLSCs was determined by cell counting kit-8 assay, carboxyfluorescein succinimidyl ester analysis, and 5-ethynyl-2'-deoxyuridine assay. The osteogenic potential of PDLSCs was tested using alkaline phosphatase staining, Alizarin Red staining, and in vivo transplantation experiments. Oil Red O staining was used to analyze adipogenic ability. The results show that human PDLSCs express both CBS and CSE and produce H2S. Blocking the generation of endogenous H2S with CBS inhibitor hydroxylamine significantly attenuated PDLSC proliferation and reduced the osteogenic and adipogenic differentiation capacity of PDLSCs. In contrast, CSE inhibitor DL-propargylglycine had no effect on PDLSC function. Exogenous H2S could inhibit the production of endogenous H2S and impair PDLSC function in a dose-dependent manner. Physiologic levels of endogenous H2S maintain the proliferation and differentiation capacity of PDLSCs, and CBS may be the main source of endogenous H2S in PDLSCs.

  9. Simulations of Biomechanical Phenomena

    Science.gov (United States)

    Gonzalez, Jose Cruz

    Recent studies have published breakthroughs in the application of finite element (FEA) studies in the design and analysis of advanced orthodontics. However, FEA has not captured bone remodeling responses to advanced orthodontics. The results of these simulations report unrealistic displacement around the nasal bridge, which impeded correlation with clinical data. Bone remodeling has been previously documented in FEA and has shown bone response to mechanical stimulus in femur bone models. However, the relationship between mechanical stimulus and bone remodeling has not been reported in orthodontic studies due to the complexity of the skull. In the current study, strain energy is used as the mechanical stimulus to control remodeling, from which density and modulus evolve. Due to the localization of forces in orthodontics, current remodeling algorithms have limited application. In turn, we developed an algorithm that dynamically collects, sorts, and bins stresses in all elements for regional remodeling based on the proximity of the element to the load. The results demonstrate that bone response to orthodontic appliances is different than that of an FEA without bone remodeling, due to load path changes based upon evolution of the bone properties. It was also found that density and moduli proximal to the load application site exhibit faster remodeling than those located remotely. Modeling another biomechanical phenomena, a 3D simulation was created to simulate recent experimental results that discovered a difference in impact mitigation properties of dense-polymer/foam bilayer structure based on the orientation of the dense-polymer with respect to the impact site. The impact energy transmitted varied in time of arrival and amplitude depending on the orientation of the structure (thin layer up or down). By creating a 3D explicit dynamic FEA simulation, it is expected to reduce costly experiments and time consumed in set up, and offer opportunities for optimization for

  10. Physiology of CA2+ signaling in human embryonic stem cell-derived neural precursors

    Czech Academy of Sciences Publication Activity Database

    Forostyak, Oksana; Romanyuk, Nataliya; Syková, Eva; Dayanithi, Govindan

    2011-01-01

    Roč. 59, S1 (2011), S119-S119 ISSN 0894-1491. [European meeting on Glial Cells in Health and Disease /10./. 13.09.2011-17.09.2011, Prague] R&D Projects: GA ČR(CZ) GAP303/11/0192 Institutional research plan: CEZ:AV0Z50390703 Keywords : calcium signaling * ATP * calcium channels Subject RIV: FH - Neurology

  11. Physiology of Ca2+ signalling in stem cells of different origins and differentiation stages.

    Czech Academy of Sciences Publication Activity Database

    Forostyak, Oksana; Forostyak, Serhiy; Kortus, Štěpán; Syková, Eva; Verkhratsky, A.; Dayanithi, Govindan

    2016-01-01

    Roč. 59, 2-3 (2016), s. 57-66 ISSN 0143-4160 R&D Projects: GA ČR(CZ) GAP304/11/2373; GA ČR(CZ) GA14-34077S; GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:68378041 Keywords : Stem cells * Ca2+ channels * Ca2+ signalling * Spontaneous Ca2+ oscillations Subject RIV: FH - Neurology Impact factor: 3.707, year: 2016

  12. Altered physiology, cell structure, and gene expression of Theobroma cacao seedlings subjected to Cu toxicity.

    Science.gov (United States)

    Souza, Vânia L; de Almeida, Alex-Alan F; Souza, Jadiel de S; Mangabeira, Pedro A O; de Jesus, Raildo M; Pirovani, Carlos P; Ahnert, Dário; Baligar, Virupax C; Loguercio, Leandro L

    2014-01-01

    Seedlings of Theobroma cacao CCN 51 genotype were grown under greenhouse conditions and exposed to increasing concentrations of Cu (0.005, 1, 2, 4, 8, 16, and 32 mg Cu L(-1)) in nutrient solution. When doses were equal or higher than 8 mg Cu L(-1), after 24 h of treatment application, leaf gas exchange was highly affected and changes in chloroplasts thylakoids of leaf mesophyll cells and plasmolysis of cells from the root cortical region were observed. In addition, cell membranes of roots and leaves were damaged. In leaves, 96 h after treatments started, increases in the percentage of electrolyte leakage through membranes were observed with increases of Cu in the nutrient solution. Moreover, there was an increase in the concentration of thiobarbituric acid-reactive substances in roots due to lipid peroxidation of membranes. Chemical analysis showed that increases in Cu concentrations in vegetative organs of T. cacao increased with the increase of the metal in the nutrient solution, but there was a greater accumulation of Cu in roots than in shoots. The excess of Cu interfered in the levels of Mn, Zn, Fe, Mg, K, and Ca in different organs of T. cacao. Analysis of gene expression via RTq-PCR showed increased levels of MT2b, SODCyt, and PER-1 expression in roots and of MT2b, PSBA, PSBO, SODCyt, and SODChI in leaves. Hence, it was concluded that Cu in nutrient solution at doses equal or above 8 mg L(-1) significantly affected leaf gas exchange, cell ultrastructure, and transport of mineral nutrients in seedlings of this T. cacao genotype.

  13. A physiologic three-dimensional cell culture system to investigate the role of decorin in matrix organisation and cell survival

    International Nuclear Information System (INIS)

    Seidler, Daniela G.; Schaefer, Liliana; Robenek, Horst; Iozzo, Renato V.; Kresse, Hans; Schoenherr, Elke

    2005-01-01

    In vivo cells exist in a three-dimensional environment generated and maintained by multiple cell-cell and cell-matrix interactions. Proteoglycans, like decorin, affect these complex interactions. Thus, we sought to investigate the role of decorin in a three-dimensional environment where the matrix was generated over time by decorin-deficient fibroblasts in the presence of L-ascorbic acid 2-phosphate. The cells were viable and proliferated in response to FGF2. Decorin was incorporated in the matrix and caused a ∼2 nm shift in the average diameter of the collagen fibrils, and the range and distribution of the fibrils became narrower and more uniform. Although there were no appreciable changes in collagen composition, we found that exogenous decorin induced the de novo synthesis of collagen I and V and cross-linked β (I). In the early phases of the three-dimensional culture, decorin reduced apoptosis. However, following the establishment of a three-dimensional matrix, the cells did not require decorin for their survival

  14. Physiological and molecular triggers for SARS-CoV membrane fusion and entry into host cells.

    Science.gov (United States)

    Millet, Jean Kaoru; Whittaker, Gary R

    2018-04-01

    During viral entry, enveloped viruses require the fusion of their lipid envelope with host cell membranes. For coronaviruses, this critical step is governed by the virally-encoded spike (S) protein, a class I viral fusion protein that has several unique features. Coronavirus entry is unusual in that it is often biphasic in nature, and can occur at or near the cell surface or in late endosomes. Recent advances in structural, biochemical and molecular biology of the coronavirus S protein has shed light on the intricacies of coronavirus entry, in particular the molecular triggers of coronavirus S-mediated membrane fusion. Furthermore, characterization of the coronavirus fusion peptide (FP), the segment of the fusion protein that inserts to a target lipid bilayer during membrane fusion, has revealed its particular attributes which imparts some of the unusual properties of the S protein, such as Ca 2+ -dependency. These unusual characteristics can explain at least in part the biphasic nature of coronavirus entry. In this review, using severe acute respiratory syndrome coronavirus (SARS-CoV) as model virus, we give an overview of advances in research on the coronavirus fusion peptide with an emphasis on its role and properties within the biological context of host cell entry. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Teaching Optical Phenomena with Tracker

    Science.gov (United States)

    Rodrigues, M.; Carvalho, P. Simeão

    2014-01-01

    Since the invention and dissemination of domestic laser pointers, observing optical phenomena is a relatively easy task. Any student can buy a laser and experience at home, in a qualitative way, the reflection, refraction and even diffraction phenomena of light. However, quantitative experiments need instruments of high precision that have a…

  16. Interfacial Transport Phenomena (Second edition)

    NARCIS (Netherlands)

    Slattery, J.C.; Sagis, L.M.C.; Oh, E.S.

    2007-01-01

    Gives a presentation of transport phenomena or continuum mechanics focused on momentum, energy, and mass transfer at interfaces. This work includes a discussion of transport phenomena at common lines or three-phase lines of contact, and a theory for the extension of continuum mechanics to the

  17. Physiology for engineers applying engineering methods to physiological systems

    CERN Document Server

    Chappell, Michael

    2016-01-01

    This book provides an introduction to qualitative and quantitative aspects of human physiology. It looks at biological and physiological processes and phenomena, including a selection of mathematical models, showing how physiological problems can be mathematically formulated and studied. It also illustrates how a wide range of engineering and physics topics, including electronics, fluid dynamics, solid mechanics and control theory can be used to describe and understand physiological processes and systems. Throughout the text there are introductions to measuring and quantifying physiological processes using both signal and imaging technologies. Physiology for Engineers describes the basic structure and models of cellular systems, the structure and function of the cardiovascular system, the electrical and mechanical activity of the heart and provides an overview of the structure and function of the respiratory and nervous systems. It also includes an introduction to the basic concepts and applications of reacti...

  18. Effects of orbital spaceflight on human osteoblastic cell physiology and gene expression

    Science.gov (United States)

    Harris, S. A.; Zhang, M.; Kidder, L. S.; Evans, G. L.; Spelsberg, T. C.; Turner, R. T.

    2000-01-01

    During long-term spaceflight, astronauts lose bone, in part due to a reduction in bone formation. It is not clear, however, whether the force imparted by gravity has direct effects on bone cells. To examine the response of bone forming cells to weightlessness, human fetal osteoblastic (hFOB) cells were cultured during the 17 day STS-80 space shuttle mission. Fractions of conditioned media were collected during flight and shortly after landing for analyses of glucose utilization and accumulation of type I collagen and prostaglandin E(2) (PGE(2)). Total cellular RNA was isolated from flight and ground control cultures after landing. Measurement of glucose levels in conditioned media indicated that glucose utilization occurred at a similar rate in flight and ground control cultures. Furthermore, the levels of type I collagen and PGE(2) accumulation in the flight and control conditioned media were indistinguishable. The steady-state levels of osteonectin, alkaline phosphatase, and osteocalcin messenger RNA (mRNA) were not significantly changed following spaceflight. Gene-specific reductions in mRNA levels for cytokines and skeletal growth factors were detected in the flight cultures using RNase protection assays. Steady-state mRNA levels for interleukin (IL)-1alpha and IL-6 were decreased 8 h following the flight and returned to control levels at 24 h postflight. Also, transforming growth factor (TGF)-beta(2) and TGF-beta(1) message levels were modestly reduced at 8 h and 24 h postflight, although the change was not statistically significant at 8 h. These data suggest that spaceflight did not significantly affect hFOB cell proliferation, expression of type I collagen, or PGE(2) production, further suggesting that the removal of osteoblastic cells from the context of the bone tissue results in a reduced ability to respond to weightlessness. However, spaceflight followed by return to earth significantly impacted the expression of cytokines and skeletal growth factors

  19. Physiological and pharmacological characterization of transmembrane acid extruders in cultured human umbilical artery smooth muscle cells

    Directory of Open Access Journals (Sweden)

    Gunng-Shinng Chen

    2015-01-01

    Full Text Available Background: Intracellular pH (pH i is a pivotal factor for cellular functions and homeostasis. Apart from passive intracellular buffering capacity, active transmembrane transporters responsible for kinetic changes of pH i impacts. Acid extrusion transporters such as Na + /H + exchanger (NHE and Na + /HCO3− cotransporter (NBC have been found to be activated when cells are in an acidic condition in different cell types. However, such far, the pH i regulators have not been characterized in human umbilical artery smooth muscle cells (HUASMCs. Materials and Methods: We, therefore, investigated the mechanism of pH i recovery from intracellular acidosis, induced by NH 4 Cl-prepulse, using pH-sensitive fluorescence dye: 2′,7′-bis(2-carboxethyl-5(6-carboxy-fluorescein in HUASMCs. Cultured HUASMCs were derived from the segments of the human umbilical artery that were obtained from women undergoing children delivery. Results: The resting pH i is 7.23 ± 0.03 when cells in HEPES (nominally HCO 3− -free buffered solution. The resting pH i is higher as 7.27 ± 0.03 when cells in CO 2 /HCO3− -buffered solution. In HEPES-buffered solution, a pH i recovery following induced intracellular acidosis could be inhibited completely by 30 μM HOE 694 (a specific NHE inhibitor or by removing [Na +]o . In 5% CO2/HCO3− -buffered solution, 30 μM HOE 694 slowed the pH i recovery from the induced intracellular acidosis only. On the contrary, HOE 694 adding together with 0.2 mM 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (a specific NBC inhibitor or removal of [Na +]o entirely blocked the acid extrusion. By using Western blot technique, we demonstrated that four different isoforms of NBC, that is, SLC4A8 (NBCBE, SLC4A7 (NBCn1, SLC4A5 (NBCe2 and SLC4A4 (NBCe1, co-exist in the HUASMCs. Conclusions: We demonstrate, for the 1 st time, that apart from the housekeeping NHE1, another Na + couple HCO3− -transporter, that is, NBC, functionally coexists to

  20. Combinatorial polymer electrospun matrices promote physiologically-relevant cardiomyogenic stem cell differentiation.

    Directory of Open Access Journals (Sweden)

    Mukesh K Gupta

    Full Text Available Myocardial infarction results in extensive cardiomyocyte death which can lead to fatal arrhythmias or congestive heart failure. Delivery of stem cells to repopulate damaged cardiac tissue may be an attractive and innovative solution for repairing the damaged heart. Instructive polymer scaffolds with a wide range of properties have been used extensively to direct the differentiation of stem cells. In this study, we have optimized the chemical and mechanical properties of an electrospun polymer mesh for directed differentiation of embryonic stem cells (ESCs towards a cardiomyogenic lineage. A combinatorial polymer library was prepared by copolymerizing three distinct subunits at varying molar ratios to tune the physicochemical properties of the resulting polymer: hydrophilic polyethylene glycol (PEG, hydrophobic poly(ε-caprolactone (PCL, and negatively-charged, carboxylated PCL (CPCL. Murine ESCs were cultured on electrospun polymeric scaffolds and their differentiation to cardiomyocytes was assessed through measurements of viability, intracellular reactive oxygen species (ROS, α-myosin heavy chain expression (α-MHC, and intracellular Ca(2+ signaling dynamics. Interestingly, ESCs on the most compliant substrate, 4%PEG-86%PCL-10%CPCL, exhibited the highest α-MHC expression as well as the most mature Ca(2+ signaling dynamics. To investigate the role of scaffold modulus in ESC differentiation, the scaffold fiber density was reduced by altering the electrospinning parameters. The reduced modulus was found to enhance α-MHC gene expression, and promote maturation of myocyte Ca(2+ handling. These data indicate that ESC-derived cardiomyocyte differentiation and maturation can be promoted by tuning the mechanical and chemical properties of polymer scaffold via copolymerization and electrospinning techniques.

  1. Manipulation of Cell Physiology Enables Gene Silencing in Well-differentiated Airway Epithelia

    Directory of Open Access Journals (Sweden)

    Sateesh Krishnamurthy

    2012-01-01

    Full Text Available The application of RNA interference-based gene silencing to the airway surface epithelium holds great promise to manipulate host and pathogen gene expression for therapeutic purposes. However, well-differentiated airway epithelia display significant barriers to double-stranded small-interfering RNA (siRNA delivery despite testing varied classes of nonviral reagents. In well-differentiated primary pig airway epithelia (PAE or human airway epithelia (HAE grown at the air–liquid interface (ALI, the delivery of a Dicer-substrate small-interfering RNA (DsiRNA duplex against hypoxanthine–guanine phosphoribosyltransferase (HPRT with several nonviral reagents showed minimal uptake and no knockdown of the target. In contrast, poorly differentiated cells (2–5-day post-seeding exhibited significant oligonucleotide internalization and target knockdown. This finding suggested that during differentiation, the barrier properties of the epithelium are modified to an extent that impedes oligonucleotide uptake. We used two methods to overcome this inefficiency. First, we tested the impact of epidermal growth factor (EGF, a known enhancer of macropinocytosis. Treatment of the cells with EGF improved oligonucleotide uptake resulting in significant but modest levels of target knockdown. Secondly, we used the connectivity map (Cmap database to correlate gene expression changes during small molecule treatments on various cells types with genes that change upon mucociliary differentiation. Several different drug classes were identified from this correlative assessment. Well-differentiated epithelia treated with DsiRNAs and LY294002, a PI3K inhibitor, significantly improved gene silencing and concomitantly reduced target protein levels. These novel findings reveal that well-differentiated airway epithelia, normally resistant to siRNA delivery, can be pretreated with small molecules to improve uptake of synthetic oligonucleotide and RNA interference (RNAi responses.

  2. Programming and reprogramming neural cells by (endo-) cannabinoids: from physiological rules to emerging therapies

    Science.gov (United States)

    Maccarrone, Mauro; Guzman, Manuel; Mackie, Ken; Doherty, Patrick; Harkany, Tibor

    2016-01-01

    Of the many signaling lipids, endocannabinoids are being increasingly recognized as having an important involvement in neuronal and glial development. Recent experimental evidence suggests that during neuronal differentiation, endocannabinoid signaling undergoes dynamic reorganization that results in a fundamental role-switch from the prenatal determination of cell fate to the homeostatic regulation of synaptic neurotransmission and bioenergetics in the mature nervous system. These studies also offer novel insights into neuropsychiatric disease mechanisms, and contribute to the public debate about the benefits and risks of cannabis use during pregnancy and in adolescence. PMID:25409697

  3. A proteomic view of cell physiology of the industrial workhorse Bacillus licheniformis.

    Science.gov (United States)

    Voigt, Birgit; Schroeter, Rebecca; Schweder, Thomas; Jürgen, Britta; Albrecht, Dirk; van Dijl, Jan Maarten; Maurer, Karl-Heinz; Hecker, Michael

    2014-12-10

    Bacillus licheniformis is known for its high protein secretion capacity and is being applied extensively as a host for the industrial production of enzymes such as proteases and amylases. In its natural environment as well as in fermentation processes the bacterium is often facing adverse conditions such as oxidative or osmotic stress or starvation for nutrients. During the last years detailed proteome and transcriptome analyses have been performed to study the adaptation of B. licheniformis cells to various stresses (heat, ethanol, oxidative or salt stress) and starvation conditions (glucose, nitrogen or phosphate starvation). A common feature of the response to all tested conditions is the downregulation of many genes encoding house-keeping proteins and, consequently, a reduced synthesis of the corresponding proteins. Induction of the general stress response (σ(B) regulon) is only observed in cells subjected to heat, ethanol or salt stress. This paper summarizes our current knowledge on general and specific stress and starvation responses of this important industrial bacterium. The importance of selected marker genes and proteins for the monitoring and optimization of B. licheniformis based fermentation processes is discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Nasal Physiology

    Science.gov (United States)

    ... Anatomy Virtual Anatomy Disclosure Statement Printer Friendly Nasal Physiology Jeremiah A. Alt, MD, PhD Noam Cohen, MD, ... control the inflammation. CONCLUSION An understanding of the physiology of the nose is critical to understand nasal ...

  5. Proteomic analysis of vascular smooth muscle cells in physiological condition and in pulmonary arterial hypertension: Toward contractile versus synthetic phenotypes.

    Science.gov (United States)

    Régent, Alexis; Ly, Kim Heang; Lofek, Sébastien; Clary, Guilhem; Tamby, Mathieu; Tamas, Nicolas; Federici, Christian; Broussard, Cédric; Chafey, Philippe; Liaudet-Coopman, Emmanuelle; Humbert, Marc; Perros, Frédéric; Mouthon, Luc

    2016-10-01

    Vascular smooth muscle cells (VSMCs) are highly specialized cells that regulate vascular tone and participate in vessel remodeling in physiological and pathological conditions. It is unclear why certain vascular pathologies involve one type of vessel and spare others. Our objective was to compare the proteomes of normal human VSMC from aorta (human aortic smooth muscle cells, HAoSMC), umbilical artery (human umbilical artery smooth muscle cells, HUASMC), pulmonary artery (HPASMC), or pulmonary artery VSMC from patients with pulmonary arterial hypertension (PAH-SMC). Proteomes of VSMC were compared by 2D DIGE and MS. Only 19 proteins were differentially expressed between HAoSMC and HPASMC while 132 and 124 were differentially expressed between HUASMC and HAoSMC or HPASMC, respectively (fold change 1.5≤ or -1.5≥, p < 0.05). As much as 336 proteins were differentially expressed between HPASMC and PAH-SMC (fold change 1.5≤ or -1.5≥, p < 0.05). HUASMC expressed increased amount of α-smooth muscle actin compared to either HPASMC or HAoSMC (although not statistically significant). In addition, PAH-SMC expressed decreased amount of smooth muscle myosin heavy chain and proliferation rate was increased compared to HPASMC thus supporting that PAH-SMC have a more synthetic phenotype. Analysis with Ingenuity identified paxillin and (embryonic lethal, abnormal vision, drosophila) like 1 (ELAVL1) as molecules linked with a lot of proteins differentially expressed between HPASMC and PAH-SMC. There was a trend toward reduced proliferation of PAH-SMC with paxillin-si-RNA and increased proliferation with ELAVL1-siRNA. Thus, VSMCs have very diverse protein content depending on their origin and this is in link with phenotypic differentiation. Paxillin targeting may be a promising treatment of PAH. ELAVL1 also participate in the regulation of PAH-SMC proliferation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. "ApoptomiRs" in vascular cells: their role in physiological and pathological angiogenesis.

    Science.gov (United States)

    Quintavalle, Cristina; Garofalo, Michela; Croce, Carlo M; Condorelli, Gerolama

    2011-10-01

    MicroRNAs (miRNAs) have emerged as crucial players regulating the magnitude of gene expression in a variety of organisms. This class of short (22 nucleotides) noncoding RNA molecules have been shown to participate in almost every cellular process investigated so far, and their deregulation is observed in different human pathologies including cancer, heart disease, and neurodegeneration. These new molecular regulators have been identified also in endothelial cells (ECs), and their role in the regulation of different aspects of the angiogenic process has been recently investigated in a variety of laboratories. The current review focuses on the research progress regarding the roles of miRNAs in vascular pathology and their potential therapeutic applications for vascular diseases associated with abnormal angiogenesis, such as cancer. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. CD4+CD25+ regulatory T cells: I. Phenotype and physiology

    DEFF Research Database (Denmark)

    Holm, Thomas Lindebo; Nielsen, Janne; Claesson, Mogens H

    2004-01-01

    The immune system protects us against foreign pathogens. However, if fine discrimination between self and non-self is not carried out properly, immunological attacks against self may be launched leading to autoimmune diseases, estimated to afflict up to 5% of the population. During the last decad...... are discussed. Finally, we address the possibility that Treg cells may play a central role in immune homeostasis, regulating not only autoimmune responses, but also immune responses toward foreign antigens.......The immune system protects us against foreign pathogens. However, if fine discrimination between self and non-self is not carried out properly, immunological attacks against self may be launched leading to autoimmune diseases, estimated to afflict up to 5% of the population. During the last decade...

  8. Intraocular in vivo imaging of pancreatic islet cell physiology/pathology

    Directory of Open Access Journals (Sweden)

    Ingo B. Leibiger

    2017-09-01

    Major conclusions: Data provided by us and others demonstrate the high versatility of this imaging platform. The use of ‘reporter islets’ engrafted in the eye, reporting on the status of in situ endogenous islets in the pancreas of the same animal, allows the identification of key-events in the development and progression of diabetes. This will not only serve as a versatile research tool but will also lay the foundation for a personalized medicine approach and will serve as a screening platform for new drugs and/or treatment protocols. ‘Metabolic’ islet transplantation, in which islets engrafted in the eye replace the endogenous beta cells, will allow for the establishment of islet-specific transgenic models and ‘humanized’ mouse models as well as serving as the basis for a new clinical transplantation site for the cure of diabetes.

  9. Severe accident phenomena

    International Nuclear Information System (INIS)

    Boneham, P.

    2003-01-01

    In this paper the following issues are considered: containment failure modes; induced RCS ruptures; overview of containment challenges; hydrogen detonations; direct containment heating; long term containment overpressure; cavity issues in VVER-440/213; phenomenology related to in-vessel retention. The paper also presents the measured and calculated detonation cell width of the H 2 -air-steam mixtures for 100 0 C and constant air density (41.6 mole/m 3 ); dependence of result class on mixture and geometric classes; experimental data on turbulent jet initiation and Deflagration to Detonation Transition (DDT) in confined volumes are also presented

  10. Rice Physiology

    Science.gov (United States)

    P.A. Counce; Davidi R. Gealy; Shi-Jean Susana Sung

    2002-01-01

    Physiology occurs tn physical space through chemical reactions constrained by anatomy and morphology, yet guided by genetics. Physiology has been called the logic of life. Genes encode structural and fimcdonal proteins. These proteins are subsequently processed to produce enzymes that direct and govern the biomechanical processes involved in the physiology of the...

  11. Advanced diffusion processes and phenomena

    CERN Document Server

    Öchsner, Andreas; Belova, Irina

    2014-01-01

    This topical volume on Advanced Diffusion Processes and Phenomena addresses diffusion in a wider sense of not only mass diffusion but also heat diffusion in fluids and solids. Both diffusion phenomena play an important role in the characterization of engineering materials and corresponding structures. Understanding these different transport phenomena at many levels, from atomistic to macro, has therefore long attracted the attention of many researchers in materials science and engineering and related disciplines. The present topical volume captures a representative cross-section of some of the

  12. Micro transport phenomena during boiling

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Xiaofeng [Tsinghua Univ., Beijing (China). Inst. of Thermal Engineering and Science

    2010-07-01

    ''Micro Transport Phenomena During Boiling'' reviews the new achievements and contributions in recent investigations at microscale. The content mainly includes (i) fundamentals for conducting investigations of micro boiling, (ii) microscale boiling and transport phenomena, (iii) boiling characteristics at microscale, (iv) some important applications of micro boiling transport phenomena. This book is intended for researchers and engineers in the field of micro energy systems, electronic cooling, and thermal management in various compact devices/systems at high heat removal and/or heat dissipation. (orig.)

  13. ATP sensing in living plant cells reveals tissue gradients and stress dynamics of energy physiology

    Science.gov (United States)

    De Col, Valentina; Fuchs, Philippe; Nietzel, Thomas; Elsässer, Marlene; Voon, Chia Pao; Candeo, Alessia; Seeliger, Ingo; Fricker, Mark D; Grefen, Christopher; Møller, Ian Max; Bassi, Andrea; Lim, Boon Leong; Zancani, Marco; Meyer, Andreas J; Costa, Alex; Wagner, Stephan; Schwarzländer, Markus

    2017-01-01

    Growth and development of plants is ultimately driven by light energy captured through photosynthesis. ATP acts as universal cellular energy cofactor fuelling all life processes, including gene expression, metabolism, and transport. Despite a mechanistic understanding of ATP biochemistry, ATP dynamics in the living plant have been largely elusive. Here, we establish MgATP2- measurement in living plants using the fluorescent protein biosensor ATeam1.03-nD/nA. We generate Arabidopsis sensor lines and investigate the sensor in vitro under conditions appropriate for the plant cytosol. We establish an assay for ATP fluxes in isolated mitochondria, and demonstrate that the sensor responds rapidly and reliably to MgATP2- changes in planta. A MgATP2- map of the Arabidopsis seedling highlights different MgATP2- concentrations between tissues and within individual cell types, such as root hairs. Progression of hypoxia reveals substantial plasticity of ATP homeostasis in seedlings, demonstrating that ATP dynamics can be monitored in the living plant. DOI: http://dx.doi.org/10.7554/eLife.26770.001 PMID:28716182

  14. ATP sensing in living plant cells reveals tissue gradients and stress dynamics of energy physiology.

    Science.gov (United States)

    De Col, Valentina; Fuchs, Philippe; Nietzel, Thomas; Elsässer, Marlene; Voon, Chia Pao; Candeo, Alessia; Seeliger, Ingo; Fricker, Mark D; Grefen, Christopher; Møller, Ian Max; Bassi, Andrea; Lim, Boon Leong; Zancani, Marco; Meyer, Andreas J; Costa, Alex; Wagner, Stephan; Schwarzländer, Markus

    2017-07-18

    Growth and development of plants is ultimately driven by light energy captured through photosynthesis. ATP acts as universal cellular energy cofactor fuelling all life processes, including gene expression, metabolism, and transport. Despite a mechanistic understanding of ATP biochemistry, ATP dynamics in the living plant have been largely elusive. Here, we establish MgATP 2- measurement in living plants using the fluorescent protein biosensor ATeam1.03-nD/nA. We generate Arabidopsis sensor lines and investigate the sensor in vitro under conditions appropriate for the plant cytosol. We establish an assay for ATP fluxes in isolated mitochondria, and demonstrate that the sensor responds rapidly and reliably to MgATP 2- changes in planta. A MgATP 2- map of the Arabidopsis seedling highlights different MgATP 2- concentrations between tissues and within individual cell types, such as root hairs. Progression of hypoxia reveals substantial plasticity of ATP homeostasis in seedlings, demonstrating that ATP dynamics can be monitored in the living plant.

  15. OnGuard, a Computational Platform for Quantitative Kinetic Modeling of Guard Cell Physiology1[W][OA

    Science.gov (United States)

    Hills, Adrian; Chen, Zhong-Hua; Amtmann, Anna; Blatt, Michael R.; Lew, Virgilio L.

    2012-01-01

    Stomatal guard cells play a key role in gas exchange for photosynthesis while minimizing transpirational water loss from plants by opening and closing the stomatal pore. Foliar gas exchange has long been incorporated into mathematical models, several of which are robust enough to recapitulate transpirational characteristics at the whole-plant and community levels. Few models of stomata have been developed from the bottom up, however, and none are sufficiently generalized to be widely applicable in predicting stomatal behavior at a cellular level. We describe here the construction of computational models for the guard cell, building on the wealth of biophysical and kinetic knowledge available for guard cell transport, signaling, and homeostasis. The OnGuard software was constructed with the HoTSig library to incorporate explicitly all of the fundamental properties for transporters at the plasma membrane and tonoplast, the salient features of osmolite metabolism, and the major controls of cytosolic-free Ca2+ concentration and pH. The library engenders a structured approach to tier and interrelate computational elements, and the OnGuard software allows ready access to parameters and equations ‘on the fly’ while enabling the network of components within each model to interact computationally. We show that an OnGuard model readily achieves stability in a set of physiologically sensible baseline or Reference States; we also show the robustness of these Reference States in adjusting to changes in environmental parameters and the activities of major groups of transporters both at the tonoplast and plasma membrane. The following article addresses the predictive power of the OnGuard model to generate unexpected and counterintuitive outputs. PMID:22635116

  16. Micro transport phenomena during boiling

    CERN Document Server

    Peng, Xiaofeng

    2011-01-01

    "Micro Transport Phenomena During Boiling" reviews the new achievements and contributions in recent investigations at microscale. It presents some original research results and discusses topics at the frontier of thermal and fluid sciences.

  17. Renormalization group and critical phenomena

    International Nuclear Information System (INIS)

    Ji Qing

    2004-01-01

    The basic clue and the main steps of renormalization group method used for the description of critical phenomena is introduced. It is pointed out that this method really reflects the most important physical features of critical phenomena, i.e. self-similarity, and set up a practical solving method from it. This way of setting up a theory according to the features of the physical system is really a good lesson for today's physicists. (author)

  18. Excellent scalability including self-heating phenomena of vertical-channel field-effect-diode type capacitor-less one transistor dynamic random access memory cell

    Science.gov (United States)

    Imamoto, Takuya; Endoh, Tetsuo

    2014-01-01

    The scalability study and the impact of the self-heating effect (SHE) on memory operation of the bulk vertical-channel field effect diode (FED) type capacitorless one transistor (1T) dynamic random access memory (DRAM) cell are investigated via device simulator for the first time. The vertical-channel FED type 1T-DRAM cell shows the excellent hold characteristics (100 ms at 358 K of ambient temperature) with large enough read current margin (1 µA/cell) even when silicon pillar diameter (D) is scaled down from 20 to 12 nm. It is also shown that by employing the vertical-channel FED type, maximum lattice temperature in the memory cell due to SHE (T_{\\text{L}}^{\\text{Max}}) can be suppressed to a negligible small value and only reach 300.6 from 300 K ambient temperature due to the low lateral electric field, while the vertical-channel bipolar junction transistor (BJT) type 1T-DRAM shows significant SHE (T_{\\text{L}}^{\\text{Max}} = 330.6 K). Moreover, this excellent thermal characteristic can be maintained even when D is scaled down from 20 to 12 nm.

  19. Impact of in vitro treatments of physiological levels of estradiol and progesterone observed in pregnancy on bovine monocyte-derived dendritic cell differentiation and maturation

    NARCIS (Netherlands)

    Pomeroy, Brianna; Klaessig, Suzanne; Schukken, Ynte

    2016-01-01

    The specific factors which regulate differentiation and maturation of dendritic cells in bovine pregnancy remain unclear. We evaluated the influence of physiologically relevant in vitro treatments of progesterone (PG) and estradiol (E2) observed in late pregnancy on the differentiation and

  20. Measurement and modelling of local phenomena in polymer electrolyte fuel cells; Messung und Modellierung lokaler Phaenomene in Polymer-Elektrolyt-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Eckl, R.

    2007-05-15

    Within the scope of this thesis, a new method for in situ current distribution measurement based on printed circuit board technology is developed and applied to polymer electrolyte fuel cells. Using the finite element method, the accuracy of this new approach is compared to conventional techniques and an estimate of the maximum uncertainty of measurement due to lateral currents is given. The effects of variable operating parameters on local electrochemical performance are studied by stationary and dynamic testing of laboratory cells with 100 cm{sup 2} active area. Based on experimental results, load conditions on the anode side are modelled and characteristic water management issues are analysed with the aid of computational fluid dynamics (CFD) simulations. (orig.)

  1. EDITORIAL: Quantum phenomena in Nanotechnology Quantum phenomena in Nanotechnology

    Science.gov (United States)

    Loss, Daniel

    2009-10-01

    Twenty years ago the Institute of Physics launched the journal Nanotechnology from its publishing house based in the home town of Paul Dirac, a legendary figure in the development of quantum mechanics at the turn of the last century. At the beginning of the 20th century, the adoption of quantum mechanical descriptions of events transformed the existing deterministic world view. But in many ways it also revolutionised the progress of research itself. For the first time since the 17th century when Francis Bacon established inductive reasoning as the means of advancing science from fact to axiom to law, theory was progressing ahead of experiments instead of providing explanations for observations that had already been made. Dirac's postulation of antimatter through purely theoretical investigation before its observation is the archetypal example of theory leading the way for experiment. The progress of nanotechnology and the development of tools and techniques that enabled the investigation of systems at the nanoscale brought with them many fascinating observations of phenomena that could only be explained through quantum mechanics, first theoretically deduced decades previously. At the nanoscale, quantum confinement effects dominate the electrical and optical properties of systems. They also render new opportunities for manipulating the response of systems. For example, a better understanding of these systems has enabled the rapid development of quantum dots with precisely determined properties, which can be exploited in a range of applications from medical imaging and photovoltaic solar cells to quantum computation, a radically new information technology being currently developed in many labs worldwide. As the first ever academic journal in nanotechnology, {\\it Nanotechnology} has been the forum for papers detailing progress of the science through extremely exciting times. In the early years of the journal, the investigation of electron spin led to the formulation

  2. A glucose anode for enzymatic fuel cells optimized for current production under physiological conditions using a design of experiment approach.

    Science.gov (United States)

    Kumar, Rakesh; Leech, Dónal

    2015-12-01

    This study reports a design of experiment methodology to investigate and improve the performance of glucose oxidizing enzyme electrodes. Enzyme electrodes were constructed by co-immobilization of amine-containing osmium redox complexes, multiwalled carbon nanotubes and glucose oxidase in a carboxymethyldextran matrix at graphite electrode surfaces to provide a 3-dimensional matrix for electrocatalytic oxidation of glucose. Optimization of the amount of the enzyme electrode components to produce the highest current density under pseudo-physiological conditions of 5 mM glucose in saline buffer at 37 °C was performed using response surface methodology. A statistical analysis showed that the proposed model had a good fit with the experimental results. From the validated model, the addition of multiwalled carbon nanotubes and carboxymethyldextran components was identified as major contributing factors to the improved performance. Based on the optimized amount of components, enzyme electrodes display current densities of 1.2±0.1 mA cm(-2) and 5.2±0.2 mA cm(-2) at 0.2 V vs. Ag/AgCl in buffer containing 5 mM and 100 mM glucose, respectively, largely consistent with the predicted values. This demonstrates that use of a design of experiment approach can be applied effectively and efficiently to improve the performance of enzyme electrodes as anodes for biofuel cell device development. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. A Novel Physiology-Based Mathematical Model to Estimate Red Blood Cell Lifespan in Different Human Age Groups.

    Science.gov (United States)

    An, Guohua; Widness, John A; Mock, Donald M; Veng-Pedersen, Peter

    2016-09-01

    Direct measurement of red blood cell (RBC) survival in humans has improved from the original accurate but limited differential agglutination technique to the current reliable, safe, and accurate biotin method. Despite this, all of these methods are time consuming and require blood sampling over several months to determine the RBC lifespan. For situations in which RBC survival information must be obtained quickly, these methods are not suitable. With the exception of adults and infants, RBC survival has not been extensively investigated in other age groups. To address this need, we developed a novel, physiology-based mathematical model that quickly estimates RBC lifespan in healthy individuals at any age. The model is based on the assumption that the total number of RBC recirculations during the lifespan of each RBC (denoted by N max) is relatively constant for all age groups. The model was initially validated using the data from our prior infant and adult biotin-labeled red blood cell studies and then extended to the other age groups. The model generated the following estimated RBC lifespans in 2-year-old, 5-year-old, 8-year-old, and 10-year-old children: 62, 74, 82, and 86 days, respectively. We speculate that this model has useful clinical applications. For example, HbA1c testing is not reliable in identifying children with diabetes because HbA1c is directly affected by RBC lifespan. Because our model can estimate RBC lifespan in children at any age, corrections to HbA1c values based on the model-generated RBC lifespan could improve diabetes diagnosis as well as therapy in children.

  4. β-carotene at physiologically attainable concentration induces apoptosis and down-regulates cell survival and antioxidant markers in human breast cancer (MCF-7) cells.

    Science.gov (United States)

    Sowmya Shree, G; Yogendra Prasad, K; Arpitha, H S; Deepika, U R; Nawneet Kumar, K; Mondal, Priya; Ganesan, P

    2017-12-01

    Although β-carotene is known for its anti-carcinogenic and antioxidant properties, a few recent epidemiological and experimental evidence show that at higher concentration it acts as pro-oxidant and induces cancer. Since the global burden of breast cancer exceeds all other types of cancer, and its incidence rates is also in increasing trend, the present study attempted to evaluate the anti-cancer molecular mechanism of β-carotene (at 1 µM concentration) isolated from Spinacia oleracea in human breast cancer (MCF-7) cells. The carotenoid was purified by open column chromatography and identified by LC-MS. The anti-proliferative effect of β-carotene at different concentrations was evaluated by WST-1 assay and the changes in cell morphology were examined by microscopic observation. The induction of apoptosis by β-carotene was observed by DAPI staining and colorimetric caspase-3 assay. The expression of cell survival, apoptotic, and antioxidant marker proteins was measured by western blot analysis. Purified β-carotene inhibited the viability of MCF-7 cells in a dose-dependent manner, which was well correlated with changes in cell morphology. Increased apoptotic cells were observed in β-carotene (1 µM)-treated cells. This apoptosis induction was associated with increased caspase-3 activity. The protein expression studies showed that β-carotene at 1 µM concentration effectively decreases the expression of the anti-apoptotic protein, Bcl-2 and PARP, and survival protein, NF-kB. It also inhibited the activation of intracellular growth signaling proteins, Akt and ERK1/2. The inhibition of Akt activation by β-carotene results in decreased phosphorylation of Bad. Further, it down-regulated antioxidant enzyme, SOD-2, and its transactivation factor (Nrf-2), and endoplasmic reticulum (ER) stress marker, XBP-1, at protein levels. These findings exhibit the key role of β-carotene even at a low physiological concentration in MCF-7 cells which further explains its

  5. Containment severe accident thermohydraulic phenomena

    International Nuclear Information System (INIS)

    Frid, W.

    1991-08-01

    This report describes and discusses the containment accident progression and the important severe accident containment thermohydraulic phenomena. The overall objective of the report is to provide a rather detailed presentation of the present status of phenomenological knowledge, including an account of relevant experimental investigations and to discuss, to some extent, the modelling approach used in the MAAP 3.0 computer code. The MAAP code has been used in Sweden as the main tool in the analysis of severe accidents. The dependence of the containment accident progression and containment phenomena on the initial conditions, which in turn are heavily dependent on the in-vessel accident progression and phenomena as well as associated uncertainties, is emphasized. The report is in three parts dealing with: * Swedish reactor containments, the severe accident mitigation programme in Sweden and containment accident progression in Swedish PWRs and BWRs as predicted by the MAAP 3.0 code. * Key non-energetic ex-vessel phenomena (melt fragmentation in water, melt quenching and coolability, core-concrete interaction and high temperature in containment). * Early containment threats due to energetic events (hydrogen combustion, high pressure melt ejection and direct containment heating, and ex-vessel steam explosions). The report concludes that our understanding of the containment severe accident progression and phenomena has improved very significantly over the parts ten years and, thereby, our ability to assess containment threats, to quantify uncertainties, and to interpret the results of experiments and computer code calculations have also increased. (au)

  6. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Gundlach Carsten

    1999-01-01

    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term 'critical phenomena'. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. This review gives an introduction to the phenomena, tries to summarize the essential features of what is happening, and then presents extensions and applications of this basic scenario. Critical phenomena are of interest particularly for creating surprising structure from simple equations, and for the light they throw on cosmic censorship and the generic dynamics of general relativity.

  7. Transport Phenomena and Materials Processing

    Science.gov (United States)

    Kou, Sindo

    1996-10-01

    An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer

  8. Whistlers and related ionospheric phenomena

    CERN Document Server

    Helliwell, Robert A

    2006-01-01

    The investigation of whistlers and related phenomena is a key element in studies of very-low-frequency propagation, satellite communication, the outer ionosphere, and solar-terrestrial relationships. This comprehensive text presents a history of the study of the phenomena and includes all the elements necessary for the calculation of the characteristics of whistlers and whistler-mode signals.An introduction and brief history are followed by a summary of the theory of whistlers and a detailed explanation of the calculation of their characteristics. Succeeding chapters offer a complete atlas of

  9. Ultrashort Phenomena in Biochemistry and Biological Signaling

    Science.gov (United States)

    Splinter, Robert

    2014-11-01

    In biological phenomena there are indications that within the long pulse-length of the action potential on millisecond scale, there is additional ultrashort perturbation encoding that provides the brain with detailed information about the origin (location) and physiological characteristics. The objective is to identify the mechanism-of-action providing the potential for encoding in biological signal propagation. The actual molecular processes involved in the initiation of the action potential have been identified to be in the femtosecond and pico-second scale. The depolarization process of the cellular membrane itself, leading to the onset of the actionpotential that is transmitted to the brain, however is in the millisecond timeframe. One example of the femtosecond chemical interaction is the photoresponse of bacteriorhodopsin. No clear indication for the spatial encoding has so far been verified. Further research will be required on a cellular signal analysis level to confirm or deny the spatial and physiological encoding in the signal wave-trains of intercellular communications and sensory stimuli. The pathological encoding process for cardiac depolarization is however very pronounced and validated, however this electro-chemical process is in the millisecond amplitude and frequency modulation spectrum.

  10. Strings, fields and critical phenomena

    International Nuclear Information System (INIS)

    Ambjoern, J.

    1987-07-01

    The connection between field theory and critical phenomena is reviewed. Emphasis is put on the use of Monte Carlo methods in the study of non-perturbative aspects of field theory. String theory is then described as a statistical theory of random surfaces and the critical behaviour is analyzed both by analytical and numerical methods. (orig.)

  11. Transport phenomena in particulate systems

    CERN Document Server

    Freire, José Teixeira; Ferreira, Maria do Carmo

    2012-01-01

    This volume spans 10 chapters covering different aspects of transport phenomena including fixed and fluidized systems, spouted beds, electrochemical and wastewater treatment reactors. This e-book will be valuable for students, engineers and researchers aiming to keep updated on the latest developments on particulate systems.

  12. [Nobel Prize for Physiology or Medicine 2002 is awarded for research into the genetic regulation of organ development and programmed cell death].

    Science.gov (United States)

    Dijkstra, C D

    2002-12-28

    The human body consists of hundreds of cell types, all originating from one fertilized egg. During the embryonic and foetal periods, the number of each cell type increases dramatically. The cells mature and become specialised to form the various tissues and organs of the body. Large numbers of cells are also formed in the adult body. Cell death is a normal process, which runs parallel to this generation of new cells. It takes place in both the foetus and adult, thereby maintaining the appropriate number of cells in the tissues. This delicate, controlled elimination of cells is termed programmed cell death or apoptosis. This year's Nobel laureates in Physiology or Medicine (Sydney Brenner, H. Robert Horvitz and John E.Sulston) have made seminal discoveries relating to the genetic regulation of organ development and programmed cell death. The nematode Caenorhabditis elegans was used as an experimental model system for following cell division and differentiation from the fertilized egg to the adult. The laureates have identified key genes that regulate organ development and programmed cell death and have also shown that corresponding genes exist in higher species, including humans. The discoveries are important for medical research and have shed new light on the pathogenesis of many diseases.

  13. The Physiology of Glucagon

    OpenAIRE

    Taborsky, Gerald J

    2010-01-01

    This short review outlines the physiology of glucagon in vivo, with an emphasis on its neural control, the author’s area of interest. Glucagon is secreted from alpha cells, which are a minority of the pancreatic islet. Anatomically, they are down stream from the majority islet beta cells. Beta-cell secretory products restrain glucagon secretion. Activation of the autonomic nerves, which innervate the islet, increases glucagon secretion.

  14. Physiology and pathophysiology of selectins, integrins, and IgSF cell adhesion molecules focusing on inflammation. A paradigm model on infectious endocarditis.

    Science.gov (United States)

    Golias, Christos; Batistatou, Anna; Bablekos, Georgios; Charalabopoulos, Alexandros; Peschos, Dimitrios; Mitsopoulos, Panagiotis; Charalabopoulos, Konstantinos

    2011-06-01

    The development of adhesion bonds, either among cells or among cells and components of the extracellular matrix, is a crucial process. These interactions are mediated by some molecules collectively known as adhesion molecules (CAMs). CAMs are ubiquitously expressed proteins playing a central role in controlling cell migration, proliferation, survival, and apoptosis. Besides their key function in physiological maintenance of tissue integrity, CAMs play an eminent role in various pathological processes such as cardiovascular disorders, atherogenesis, atherosclerotic plaque progression and regulation of the inflammatory response. CAMs such as selectins, integrins, and immunoglobulin superfamily take part in interactions between leukocyte and vascular endothelium (leukocyte rolling, arrest, firm adhesion, migration). Experimental data and pathologic observations support the assumption that pathogenic microorganisms attach to vascular endothelial cells or sites of vascular injury initiating intravascular infections. In this review a paradigm focusing on cell adhesion molecules pathophysiology and infective endocarditis development is given.

  15. Physiological parameters

    International Nuclear Information System (INIS)

    Natera, E.S.

    1998-01-01

    The physiological characteristics of man depend on the intake, metabolism and excretion of stable elements from food, water, and air. The physiological behavior of natural radionuclides and radionuclides from nuclear weapons testing and from the utilization of nuclear energy is believed to follow the pattern of stable elements. Hence information on the normal physiological processes occurring in the human body plays an important role in the assessment of the radiation dose received by man. Two important physiological parameters needed for internal dose determination are the pulmonary function and the water balance. In the Coordinated Research Programme on the characterization of Asian population, five participants submitted data on these physiological characteristics - China, India, Japan, Philippines and Viet Nam. During the CRP, data on other pertinent characteristics such as physical and dietary were simultaneously being collected. Hence, the information on the physiological characteristics alone, coming from the five participants were not complete and are probably not sufficient to establish standard values for the Reference Asian Man. Nonetheless, the data collected is a valuable contribution to this research programme

  16. Bioprocess development workflow: Transferable physiological knowledge instead of technological correlations.

    Science.gov (United States)

    Reichelt, Wieland N; Haas, Florian; Sagmeister, Patrick; Herwig, Christoph

    2017-01-01

    Microbial bioprocesses need to be designed to be transferable from lab scale to production scale as well as between setups. Although substantial effort is invested to control technological parameters, usually the only true constant parameter is the actual producer of the product: the cell. Hence, instead of solely controlling technological process parameters, the focus should be increasingly laid on physiological parameters. This contribution aims at illustrating a workflow of data life cycle management with special focus on physiology. Information processing condenses the data into physiological variables, while information mining condenses the variables further into physiological descriptors. This basis facilitates data analysis for a physiological explanation for observed phenomena in productivity. Targeting transferability, we demonstrate this workflow using an industrially relevant Escherichia coli process for recombinant protein production and substantiate the following three points: (1) The postinduction phase is independent in terms of productivity and physiology from the preinduction variables specific growth rate and biomass at induction. (2) The specific substrate uptake rate during induction phase was found to significantly impact the maximum specific product titer. (3) The time point of maximum specific titer can be predicted by an easy accessible physiological variable: while the maximum specific titers were reached at different time points (19.8 ± 7.6 h), those maxima were reached all within a very narrow window of cumulatively consumed substrate dSn (3.1 ± 0.3 g/g). Concluding, this contribution provides a workflow on how to gain a physiological view on the process and illustrates potential benefits. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:261-270, 2017. © 2016 American Institute of Chemical Engineers.

  17. A unique combination of anatomy and physiology in cells of the rat paralaminar thalamic nuclei adjacent to the medial geniculate body

    Science.gov (United States)

    Smith, Philip H.; Bartlett, Edward L.; Kowalkowski, Anna

    2010-01-01

    The medial geniculate body (MGB) has three major subdivisions - ventral (MGV), dorsal (MGD) and medial (MGM). MGM is linked with paralaminar nuclei that are situated medial and ventral to MGV/MGD. Paralaminar nuclei have unique inputs and outputs when compared with MGV and MGD and have been linked to circuitry underlying some important functional roles. We recorded intracellularly from cells in the paralaminar nuclei in vitro. We found that they possess an unusual combination of anatomical and physiological features when compared to those reported for “standard” thalamic neurons seen in the MGV/MGD and elsewhere in the thalamus. Compared to MGV/MGD neurons, anatomically, 1) paralaminar cell dendrites can be long, branch sparingly and encompass a much larger area. 2) their dendrites may be smooth but can have well defined spines and 3) their axons can have collaterals that branch locally within the same or nearby paralaminar nuclei. When compared to MGV/MGD neurons physiologically 1) their spikes are larger in amplitude and can be shorter in duration and 2) can have dual afterhyperpolarizations with fast and slow components and 3) they can have a reduction or complete absence of the low threshold, voltage-sensitive calcium conductance that reduces or eliminates the voltage-dependent burst response. We also recorded from cells in the parafascicular nucleus, a nucleus of the posterior intralaminar nuclear group, because they have unusual anatomical features that are similar to some of our paralaminar cells. Like the labeled paralaminar cells, parafascicular cells had physiological features distinguishing them from typical thalamic neurons. PMID:16566009

  18. Transport phenomena in multiphase flows

    CERN Document Server

    Mauri, Roberto

    2015-01-01

    This textbook provides a thorough presentation of the phenomena related to the transport of mass, momentum and energy.  It lays all the basic physical principles, then for the more advanced readers, it offers an in-depth treatment with advanced mathematical derivations and ends with some useful applications of the models and equations in specific settings. The important idea behind the book is to unify all types of transport phenomena, describing them within a common framework in terms of cause and effect, respectively represented by the driving force and the flux of the transported quantity. The approach and presentation are original in that the book starts with a general description of transport processes, providing the macroscopic balance relations of fluid dynamics and heat and mass transfer, before diving into the mathematical realm of continuum mechanics to derive the microscopic governing equations at the microscopic level. The book is a modular teaching tool and can be used either for an introductory...

  19. Solar Neutrons and Related Phenomena

    CERN Document Server

    Dorman, Lev

    2010-01-01

    This book presents the first comprehensive compilation and review of the extensive body of experimental and theoretical material on solar neutrons and related phenomena published in the scientific literature over the last sixty years. Phenomena related to solar neutrons are more specifically: the decay products of solar neutrons solar gamma rays generated in processes like nuclear reactions between solar energetic charged particles and matter of the solar atmosphere, as well as by the capture of solar neutrons by hydrogen atoms in the solar atmosphere the propagation of solar neutrons, solar gamma rays and other secondary particles through the solar photosphere, chromosphere and corona, as well as through interplanetary space and through the Earth's atmosphere. Models and simulations of particle acceleration, interactions, and propagation processes show that observations of solar neutrons and gamma rays in space and in the Earth's atmosphere yield essential and unique information on the source function of ene...

  20. Exercise Effects on Sleep Physiology

    OpenAIRE

    Uchida, Sunao; Shioda, Kohei; Morita, Yuko; Kubota, Chie; Ganeko, Masashi; Takeda, Noriko

    2012-01-01

    This mini-review focuses on the effects of exercise on sleep. In its early days, sleep research largely focused on central nervous system (CNS) physiology using standardized tabulations of several sleep-specific landmark electroencephalogram (EEG) waveforms. Though coarse, this method has enabled the observation and inspection of numerous uninterrupted sleep phenomena. The research on the effects of exercise on sleep began, in the 1960s, with a focus primarily on sleep related EEG changes (CN...

  1. Exercise Effects on Sleep Physiology

    OpenAIRE

    Sunao eUchida; Kohei eShioda; Yuko eMorita; Chie eKubota; Masashi eGaneko; Noriko eTakeda; Noriko eTakeda

    2012-01-01

    This mini-review focuses on the effects of exercise on sleep. In its early days, sleep research largely focused on central nervous system (CNS) physiology using standardized tabulations of several sleep-specific landmark electroencephalogram (EEG) waveforms. Though coarse, this method has enabled the observation and inspection of numerous uninterrupted sleep phenomena. Thus, research on the effects of exercise on sleep began, in the 1960’s, with a focus primarily on sleep EEG (CNS sleep) c...

  2. Mathematical Modeling of Diverse Phenomena

    Science.gov (United States)

    Howard, J. C.

    1979-01-01

    Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

  3. Gravitational anomaly and transport phenomena

    OpenAIRE

    Landsteiner, Karl

    2011-01-01

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficie...

  4. Plant Physiology and Development

    DEFF Research Database (Denmark)

    Taiz, Lincoln; Zeiger, Eduardo; Møller, Ian Max

    Throughout its twenty-two year history, the authors of Plant Physiology have continually updated the book to incorporate the latest advances in plant biology and implement pedagogical improvements requested by adopters. This has made Plant Physiology the most authoritative, comprehensive...... Physiology and Development. As before, Unit III begins with updated chapters on Cell Walls and Signals and Signal Transduction. The latter chapter has been expanded to include a discussion of major signaling molecules, such as calcium ions and plant hormones. A new, unified chapter entitled Signals from...... to describing the stages of development from embryogenesis to senescence and the many physiological and environmental factors that regulate them. The result provides students with an improved understanding of the integration of hormones and other signaling agents in developmental regulation...

  5. Feeling the right force: How to contextualize the cell mechanical behavior in physiologic turnover and pathologic evolution of the cardiovascular system.

    Science.gov (United States)

    Pesce, Maurizio; Santoro, Rosaria

    2017-03-01

    Although traditionally linked to the physiology of tissues in 'motion', the ability of the cells to transduce external forces into coordinated gene expression programs is emerging as an integral component of the fundamental structural organization of multicellular organisms with consequences for cell differentiation even from the beginning of embryonic development. The ability of the cells to 'feel' the surrounding mechanical environment, even in the absence of tissue motion, is then translated into 'positional' or 'social' sensing that instructs, before the organ renewal, the correct patterning of the embryos. In the present review, we will highlight how these basic concepts, emerging from the employment of novel cell engineering tools, can be linked to pathophysiology of the cardiovascular system, and may contribute to understanding the molecular bases of some of the major cardiovascular diseases like heart failure, heart valve stenosis and failure of the venous aorto-coronary bypass. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. A New Integrated Lab-on-a-Chip System for Fast Dynamic Study of Mammalian Cells under Physiological Conditions in Bioreactor

    Directory of Open Access Journals (Sweden)

    An-Ping Zeng

    2013-05-01

    Full Text Available For the quantitative analysis of cellular metabolism and its dynamics it is essential to achieve rapid sampling, fast quenching of metabolism and the removal of extracellular metabolites. Common manual sample preparation methods and protocols for cells are time-consuming and often lead to the loss of physiological conditions. In this work, we present a microchip-bioreactor setup which provides an integrated and rapid sample preparation of mammalian cells. The lab-on-a-chip system consists of five connected units that allow sample treatment, mixing and incubation of the cells, followed by cell separation and simultaneous exchange of media within seconds. This microsystem is directly integrated into a bioreactor for mammalian cell cultivation. By applying overpressure (2 bar onto the bioreactor, this setup allows pulsation free, defined, fast, and continuous sampling. Experiments evince that Chinese Hamster Ovary cells (CHO-K1 can be separated from the culture broth and transferred into a new medium efficiently. Furthermore, this setup permits the treatment of cells for a defined time (9 s or 18 s which can be utilized for pulse experiments, quenching of cell metabolism, and/or another defined chemical treatment. Proof of concept experiments were performed using glutamine containing medium for pulse experiments. Continuous sampling of cells showed a high reproducibility over a period of 18 h.

  7. Regulatory Physiology

    Science.gov (United States)

    Lane, Helen W.; Whitson, Peggy A.; Putcha, Lakshmi; Baker, Ellen; Smith, Scott M.; Stewart, Karen; Gretebeck, Randall; Nimmagudda, R. R.; Schoeller, Dale A.; Davis-Street, Janis

    1999-01-01

    As noted elsewhere in this report, a central goal of the Extended Duration Orbiter Medical Project (EDOMP) was to ensure that cardiovascular and muscle function were adequate to perform an emergency egress after 16 days of spaceflight. The goals of the Regulatory Physiology component of the EDOMP were to identify and subsequently ameliorate those biochemical and nutritional factors that deplete physiological reserves or increase risk for disease, and to facilitate the development of effective muscle, exercise, and cardiovascular countermeasures. The component investigations designed to meet these goals focused on biochemical and physiological aspects of nutrition and metabolism, the risk of renal (kidney) stone formation, gastrointestinal function, and sleep in space. Investigations involved both ground-based protocols to validate proposed methods and flight studies to test those methods. Two hardware tests were also completed.

  8. Fast Particle Methods for Multiscale Phenomena Simulations

    Science.gov (United States)

    Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

    2000-01-01

    We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

  9. G Protein–Coupled Receptor (GPCR) Expression in Native Cells: “Novel” endoGPCRs as Physiologic Regulators and Therapeutic Targets

    Science.gov (United States)

    Wilderman, Andrea; Zambon, Alexander C.; Snead, Aaron N.; Murray, Fiona; Aroonsakool, Nakon; McDonald, Daniel S.; Zhou, Shu; McCann, Thalia; Zhang, Lingzhi; Sriram, Krishna; Chinn, Amy M.; Michkov, Alexander V.; Lynch, Rebecca M.; Overland, Aaron C.; Corriden, Ross

    2015-01-01

    G protein–coupled receptors (GPCRs), the largest family of signaling receptors in the human genome, are also the largest class of targets of approved drugs. Are the optimal GPCRs (in terms of efficacy and safety) currently targeted therapeutically? Especially given the large number (∼120) of orphan GPCRs (which lack known physiologic agonists), it is likely that previously unrecognized GPCRs, especially orphan receptors, regulate cell function and can be therapeutic targets. Knowledge is limited regarding the diversity and identity of GPCRs that are activated by endogenous ligands and that native cells express. Here, we review approaches to define GPCR expression in tissues and cells and results from studies using these approaches. We identify problems with the available data and suggest future ways to identify and validate the physiologic and therapeutic roles of previously unrecognized GPCRs. We propose that a particularly useful approach to identify functionally important GPCRs with therapeutic potential will be to focus on receptors that show selective increases in expression in diseased cells from patients and experimental animals. PMID:25737495

  10. Effect of the fermentation pH on the storage stability of Lactobacillus rhamnosus preparations and suitability of in vitro analyses of cell physiological functions to predict it.

    Science.gov (United States)

    Saarela, M H; Alakomi, H-L; Puhakka, A; Mättö, J

    2009-04-01

    To investigate how cell physiological functions can predict the stability of freeze-dried probiotics. In addition, the effect of the fermentation pH on the stability of probiotics was investigated. Fermenter-grown (pH 5.8 or 5.0) Lactobacillus rhamnosus cells were freeze-dried and their survival was evaluated during storage at 37 degrees C, in apple juice and during acid [hydrochloric acid (HCl) and malic acid] and bile exposure. Cells grown at pH 5.0 were generally coping better with acid-stress than cells grown at pH 5.8. Cells were more sensitive to malic acid compared with HCl. Short-term stability results of Lact. rhamnosus cells in malic acid correlated well with the long-term stability results in apple juice, whereas the results of cell membrane integrity studies were in accordance with bile exposure results. Malic acid exposure can prove useful in evaluating the long-term stability of probiotic preparations in apple juice. Fermentation at reduced pH may ensure a better performance of Lact. rhamnosus cells during the subsequent acid-stress. The beneficial effect of lowered fermentation pH to Lact. rhamnosus stability during storage in apple juice and the usefulness of malic acid test in predicting the stability were shown.

  11. Exercise physiology

    DEFF Research Database (Denmark)

    Kiens, Bente; Richter, Erik; Wojtaszewski, Jørgen

    2014-01-01

    The passing of Professor Bengt Saltin on September 12, 2014 truly marks the end of an era. As editor of the Journal of Applied Physiology and one of Bengt’s many collaborators and colleagues, I wanted the Journal to celebrate his many seminal contributions by means of an Editorial. Professor Bente...

  12. Nonlinear Dynamic Phenomena in Mechanics

    CERN Document Server

    Warminski, Jerzy; Cartmell, Matthew P

    2012-01-01

    Nonlinear phenomena should play a crucial role in the design and control of engineering systems and structures as they can drastically change the prevailing dynamical responses. This book covers theoretical and applications-based problems of nonlinear dynamics concerned with both discrete and continuous systems of interest in civil and mechanical engineering. They include pendulum-like systems, slender footbridges, shape memory alloys, sagged elastic cables and non-smooth problems. Pendulums can be used as a dynamic absorber mounted in high buildings, bridges or chimneys. Geometrical nonlinear

  13. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2001-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in

  14. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2000-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. No longer an area of specialist interest, it has acquired a central focus in condensed matter studies. The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable information on important recent developments.The two review articles in this volume complement each other in a remarkable way. Both deal with what m

  15. Violent phenomena in the Universe

    CERN Document Server

    Narlikar, Jayant V

    2007-01-01

    The serenity of a clear night sky belies the evidence-gathered by balloons, rockets, satellites, and telescopes-that the universe contains centers of furious activity that pour out vast amounts of energy, some in regular cycles and some in gigantic bursts. This reader-friendly book, acclaimed by Nature as ""excellent and uncompromising,"" traces the development of modern astrophysics and its explanations of these startling celestial fireworks.This lively narrative ranges from the gravitational theories of Newton and Einstein to recent exciting discoveries of such violent phenomena as supernova

  16. Gravitational anomaly and transport phenomena.

    Science.gov (United States)

    Landsteiner, Karl; Megías, Eugenio; Pena-Benitez, Francisco

    2011-07-08

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

  17. Phenomena and Diosignes of Aratous

    Science.gov (United States)

    Avgoloupis, S. I.

    2013-01-01

    Aratous (305-240B.C.) was a singular intellectual, writer and poet which engage himself to compose a very interesting astronomical poet, using the "Dactylous sixstage' style, the formal style of the ancient Greek Epic poetry. This astronomic poem of Aratous "Phenomena and Diosignes" became very favorite reading during the Alexandrine, the Romman and the Byzandin eras as well and had received many praises from significant poets and particularly from Hipparchous and from Theonas from Alexandria, an astronomer of 4rth century A.C.(in Greeks)

  18. Quantum theory of collective phenomena

    CERN Document Server

    Sewell, G L

    2014-01-01

    ""An excellent and competent introduction to the field … [and] … a source of information for the expert."" - Physics Today""This a book of major importance…. I trust that this book will be used as a basis for the teaching of a balanced, modern and rigorous course on statistical mechanics in all universities."" - Bulletin of the London Mathematical Society""This is one of the best introductions to the subject, and it is strongly recommended to anyone interested in collective phenomena."" - Physics Bulletin ""The book may be recommended for students as a well-balanced introduction to this rich s

  19. Radiation-induced DNA damage in tumors and normal tissues. II. Influence of dose, residual DNA damage and physiological factors in oxygenated cells

    International Nuclear Information System (INIS)

    Zhang, H.; Wheeler, K.T.

    1994-01-01

    Detection and quantification of hypoxic cells in solid tumors is important for many experimental and clinical situations. Several laboratories, including ours, have suggested that assays which measure radiation-induced DNA strand breaks and DNA-protein crosslinks (DPCs) might be used to detect or quantify hypoxic cells in tumors and normal tissues. Recently, we demonstrated the feasibility of using an alkaline elution assay that measures strand breaks and DPCs to detect and/or quantify hypoxic cells in tissues. For this approach to be valid, DPCs must not be formed to any great extent in irradiated oxygenated cells, and the formation and repair of strand breaks and DPCs in oxygenated cells must not be modified appreciably by physiological factors (e.g., temperature, pH and nutrient depletion) that are often found in solid tumors. To address these issues, two sets of experiments were performed. In one set of experiments, oxygenated 9L cells in tissue culture, subcutaneous 9L tumors and rat cerebella were irradiated with doses of 15 or 50 Gy and allowed to repair until the residual strand break damage was low enough to detect DPCs. In another set of experiments, oxygenated exponentially growing or plateau-phase 9L cells in tissue culture were irradiated with a dose of 15 Gy at 37 or 20 degrees C, while the cells were maintained at a pH of either 6.6 or 7.3. DNA-protein crosslinks were formed in oxygenated cells about 100 times less efficiently than in hypoxic cells. In addition, temperature, pH, nutrient depletion and growth phase did not appreciably alter the formation and repair of strand breaks or the formation of DPCs in oxygenated 9L cells. These results support the use of this DNA damage assay for the detection and quantification of hypoxic cells in solid tumors. 27 refs., 5 tabs

  20. The physiological expression of scavenger receptor SR-B1 in canine endometrial and placental epithelial cells and its potential involvement in pathogenesis of pyometra.

    Science.gov (United States)

    Gabriel, C; Becher-Deichsel, A; Hlavaty, J; Mair, G; Walter, I

    2016-06-01

    Pyometra, the purulent inflammation of the uterus, is a common uterine disease of bitches that has potentially life-threatening consequences. The opportunistic bacterial infection of the uterus often progresses into the serious systemic inflammatory response syndrome. In a previous study, we characterized epithelial foam cells in the canine endometrial surface occurring in metestrus, and we regularly observed pronounced epithelial foam-cell formations in pyometra-affected uteri. Therefore, it was assumed that the mechanism behind lipid droplet accumulation in surface epithelial cells might even increase bacterial binding capacity and promote pyometra development. Lipid droplet accumulation in epithelial cells is accomplished via specialized lipid receptors called scavenger receptors (SR). Scavenger receptor class B type 1 (SR-B1) is an important receptor for lipid accumulation in diverse cell types, but it is also a strong binding partner for bacteria, and thereby enhances bacterial adhesion and clinical signs of systemic inflammatory response syndrome. In the present study, after the isolation of metestrous surface epithelial cells from canine uteri by laser capture microdissection, SR-B1 was identified at the messenger RNA (mRNA) level by quantitative real time polymerase chain reaction and also at the protein level by means of immunohistochemistry. In pyometra-affected uteri, SR-B1 mRNA expression was higher than that in the healthy control samples, and SR-B1 protein was expressed in the surface and crypt epithelial cells. Furthermore, to understand the physiological role of SR-B1 expression in the metestrus surface epithelial cells, we investigated its expression in the epithelial cells of the glandular chambers of canine placenta in different stages of gestation because these cells are also characterized by lipid droplet accumulation. SR-B1 was present in the placental epithelial cells of the glandular chambers from 25 to 30 and 45 to 50 days of gestation

  1. Transport phenomena in nanoporous materials.

    Science.gov (United States)

    Kärger, Jörg

    2015-01-12

    Diffusion, that is, the irregular movement of atoms and molecules, is a universal phenomenon of mass transfer occurring in all states of matter. It is of equal importance for fundamental research and technological applications. The present review deals with the challenges of the reliable observation of these phenomena in nanoporous materials. Starting with a survey of the different variants of diffusion measurement, it highlights the potentials of "microscopic" techniques, notably the pulsed field gradient (PFG) technique of NMR and the techniques of microimaging by interference microscopy (IFM) and IR microscopy (IRM). Considering ensembles of guest molecules, these techniques are able to directly record mass transfer phenomena over distances of typically micrometers. Their concerted application has given rise to the clarification of long-standing discrepancies, notably between microscopic equilibrium and macroscopic non-equilibrium measurements, and to a wealth of new information about molecular transport under confinement, hitherto often inaccessible and sometimes even unimaginable. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Data on how several physiological parameters of stored red blood cells are similar in glucose 6-phosphate dehydrogenase deficient and sufficient donors

    Directory of Open Access Journals (Sweden)

    Vassilis L. Tzounakas

    2016-09-01

    Full Text Available This article contains data on the variation in several physiological parameters of red blood cells (RBCs donated by eligible glucose-6-phosphate dehydrogenase (G6PD deficient donors during storage in standard blood bank conditions compared to control, G6PD sufficient (G6PD+ cells. Intracellular reactive oxygen species (ROS generation, cell fragility and membrane exovesiculation were measured in RBCs throughout the storage period, with or without stimulation by oxidants, supplementation of N-acetylcysteine and energy depletion, following incubation of stored cells for 24 h at 37 °C. Apart from cell characteristics, the total or uric acid-dependent antioxidant capacity of the supernatant in addition to extracellular potassium concentration was determined in RBC units. Finally, procoagulant activity and protein carbonylation levels were measured in the microparticles population. Further information can be found in “Glucose 6-phosphate dehydrogenase deficient subjects may be better “storers” than donors of red blood cells” [1]. Keywords: G6PD deficiency, Red blood cell storage lesion, Oxidative stress, Cell fragility, Microparticles

  3. Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells

    Directory of Open Access Journals (Sweden)

    Watson Cheryl S

    2010-10-01

    Full Text Available Abstract Background Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the responses to these compounds are typically measured individually, they usually contaminate organisms that already have endogenous estrogens present. Therefore, we used quantitative medium-throughput screening assays to measure the effects of physiologic estrogens in combination with these xenoestrogens. Methods We studied the effects of low concentrations of endogenous estrogens (estradiol, estriol, and estrone at 10 pM (representing pre-development levels, and 1 nM (representing higher cycle-dependent and pregnancy levels in combinations with the same levels of xenoestrogens in GH3/B6/F10 pituitary cells. These levels of xenoestrogens represent extremely low contamination levels. We monitored calcium entry into cells using Fura-2 fluorescence imaging of single cells. Prolactin release was measured by radio-immunoassay. Extracellular-regulated kinase (1 and 2 phospho-activations and the levels of three estrogen receptors in the cell membrane (ERα, ERβ, and GPER were measured using a quantitative plate immunoassay of fixed cells either permeabilized or nonpermeabilized (respectively. Results All xenoestrogens caused responses at these concentrations, and had disruptive effects on the actions of physiologic estrogens. Xenoestrogens reduced the % of cells that responded to estradiol via calcium channel opening. They also inhibited the activation (phosphorylation of extracellular-regulated kinases at some concentrations. They either inhibited or enhanced rapid prolactin release, depending upon concentration. These latter two dose-responses were nonmonotonic, a characteristic of nongenomic estrogenic responses. Conclusions Responses mediated by endogenous estrogens representing different life stages are

  4. Combinations of physiologic estrogens with xenoestrogens alter calcium and kinase responses, prolactin release, and membrane estrogen receptor trafficking in rat pituitary cells.

    Science.gov (United States)

    Jeng, Yow-Jiun; Kochukov, Mikhail; Watson, Cheryl S

    2010-10-15

    Xenoestrogens such as alkylphenols and the structurally related plastic byproduct bisphenol A have recently been shown to act potently via nongenomic signaling pathways and the membrane version of estrogen receptor-α. Though the responses to these compounds are typically measured individually, they usually contaminate organisms that already have endogenous estrogens present. Therefore, we used quantitative medium-throughput screening assays to measure the effects of physiologic estrogens in combination with these xenoestrogens. We studied the effects of low concentrations of endogenous estrogens (estradiol, estriol, and estrone) at 10 pM (representing pre-development levels), and 1 nM (representing higher cycle-dependent and pregnancy levels) in combinations with the same levels of xenoestrogens in GH3/B6/F10 pituitary cells. These levels of xenoestrogens represent extremely low contamination levels. We monitored calcium entry into cells using Fura-2 fluorescence imaging of single cells. Prolactin release was measured by radio-immunoassay. Extracellular-regulated kinase (1 and 2) phospho-activations and the levels of three estrogen receptors in the cell membrane (ERα, ERβ, and GPER) were measured using a quantitative plate immunoassay of fixed cells either permeabilized or nonpermeabilized (respectively). All xenoestrogens caused responses at these concentrations, and had disruptive effects on the actions of physiologic estrogens. Xenoestrogens reduced the % of cells that responded to estradiol via calcium channel opening. They also inhibited the activation (phosphorylation) of extracellular-regulated kinases at some concentrations. They either inhibited or enhanced rapid prolactin release, depending upon concentration. These latter two dose-responses were nonmonotonic, a characteristic of nongenomic estrogenic responses. Responses mediated by endogenous estrogens representing different life stages are vulnerable to very low concentrations of these structurally

  5. Natural phenomena hazards, Hanford Site, Washington

    International Nuclear Information System (INIS)

    Conrads, T.J.

    1998-01-01

    This document presents the natural phenomena hazard loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, and supports development of double-shell tank systems specifications at the Hanford Site in south-central Washington State. The natural phenomena covered are seismic, flood, wind, volcanic ash, lightning, snow, temperature, solar radiation, suspended sediment, and relative humidity

  6. Late post-irradiation phenomena in mammalian cell populations. Pt. 3. Characteristics of the slowly growing clones isolated from X-irradiated L5178Y-S cell cultures

    International Nuclear Information System (INIS)

    Beer, J.Z.; Szumiel, I.

    1975-01-01

    Populations of murine leukaemic lymphoblasts L5178Y-S irradiated with 300 rads of X-rays in vitro were analysed by serial clonings. It was found that the latent radiation-induced heritable lesions can be revealed by this technique. Approximately 100 slowly growing cell sublines with doubling times varying from 12 to 25 h, obtained by cloning, were assayed for: viability, cloning efficiency, mitotic index, labelling index (1 h and 24 h exposure to 3 H-thymidine), 3 H-thymidine incorporation rate, histone Fl phosphorous content, radiosensitivity, cell cycle disturbances, DNA per cell content, karyotype changes. The slowly-growing clones show normal or almost normal viability but have reduced cloning efficiencies. No correlations were found between the subline's doubling time or time interval between its isolation and determination, on one hand, and mitotic index or 1 h labelling index, on the other hand. 3 H-thymidine incorporation rate and histone Fl phosphorylation degree were inversely related to the subline's doubling time. Increased radiosensitivity of the slowly growing sublines, observed soon after their isolation, indicates that the heritable lesions in the cells studied are radiation-induced rather than selected. Autoradiographic analysis of the cell cycle indicates: heterogeneity of the slowly growing cell lines, occurence of cells with prolonged G2 phase and a possibility that in more severely damaged cells S phase is also affected. (author)

  7. PHYSIOLOGICAL, CYTOLOGICAL AND BIOCHEMICAL STABILITY OF Medicago sativa L. CELL CULTURE AFTER 27 YEARS OF CRYOGENIC STORAGE.

    Science.gov (United States)

    Volkova, L A; Urmantseva, V V; Popova, E V; Nosov, A M

    2015-01-01

    The efficiency of long-term cryogenic storage to prevent somaclonal variations in plant cell cultures and retain their major cytogenetic and biochemical traits remains under debate. In particular, it is not clear how stress conditions associated with cryopreservation, such as low temperature, dehydration and toxic action of some cryoprotectants (DMSO in particular), affect post-storage regrowth and genetic integrity of cell samples. We assessed growth, cytogenetic and biochemical characteristics of the peroxidase-producing strain of Medicago sativa L. cell culture recovered after 27 years of cryogenic storage as compared to the same culture before cryopreservation. In 1984, M. sativa L. cell culture was cryopreserved using programmed freezing and 7% DMSO as a cryoprotectant. In 2011, after rewarming in a water bath at 40 degree C for 90 s, cell culture was recovered and proliferated. Viability, growth profile, mitotic index, ploidy level, peroxidase activity and cell response to hypothermia and osmotic stress were compared between the recovered and the initial cell cultures using the records available from 1984. Viability of alfalfa cell culture after rewarming was below 20% but it increased to 80% by the 27th subculture cycle. Recovered culture showed higher mitotic activity and increased number of haploid and diploid cells compared to the initial cell line. Both peroxidase activity and response to abiotic stress in the recovered cell culture were similar to that of the initial culture. Cryopreservation by programmed freezing was effective at retaining the main characteristics of M. sativa undifferentiated cell culture after 27 years of storage. According to available data, this is longest period of successful cryopreservation of plant cell cultures reported so far. After storage, there was no evidence that DMSO had any detrimental effect on cell viability, growth or cytogenetics.

  8. Electrostatic phenomena in organic semiconductors: fundamentals and implications for photovoltaics.

    Science.gov (United States)

    D'Avino, Gabriele; Muccioli, Luca; Castet, Frédéric; Poelking, Carl; Andrienko, Denis; Soos, Zoltán G; Cornil, Jérôme; Beljonne, David

    2016-11-02

    This review summarizes the current understanding of electrostatic phenomena in ordered and disordered organic semiconductors, outlines numerical schemes developed for quantitative evaluation of electrostatic and induction contributions to ionization potentials and electron affinities of organic molecules in a solid state, and illustrates two applications of these techniques: interpretation of photoelectron spectroscopy of thin films and energetics of heterointerfaces in organic solar cells.

  9. Mental deterioration correlates with response of natural killer (NK) cell activity to physiological modifiers in patients with short history of Alzheimer's disease.

    Science.gov (United States)

    Masera, Rosa Gabriella; Prolo, Paolo; Sartori, Maria Luisa; Staurenghi, Antonio; Griot, Giulietta; Ravizza, Luigi; Dovio, Andrea; Chiappelli, Francesco; Angeli, Alberto

    2002-05-01

    Natural killer (NK) cell activity of peripheral blood mononuclear (PBM) cells was measured in 16 subjects with mild to moderate senile dementia of Alzheimer's type (sDAT) chosen for short history of disease and no medication, and in 17 age- and sex-matched controls. Levels of cytotoxicity at baseline and after PBM cell exposure to modifiers either negative (cortisol 10(-6) M) or positive (rIL-2 650 IU/ml and rIFN-gamma 100 UI/ml, respectively) were related to indices of hypothalamic-pituitary-adrenal (HPA) function and Gottfries Bråne Rating Scale (GBS) score for mental deterioration. Spontaneous NK cell activity was not significantly different in sDAT subjects vs controls. In vitro inhibition by cortisol was lower in sDAT (Pmild cognitive impairment and short history of sDAT show abnormal responsiveness of NK cell activity to physiological modifiers while maintaining normal spontaneous activity. Furthermore, data are compatible with partial glucocorticoid resistance at the immune level. Progressing sDAT longitudinal studies are needed to address: i) the clinical applicability of these abnormalities as prognostic factors; ii) the role played by pro-opiomelanocortin (POMC)-derived peptides and adrenal androgens in the control of NK cell activity.

  10. Expression of Siglec-11 by human and chimpanzee ovarian stromal cells, with uniquely human ligands: implications for human ovarian physiology and pathology

    Science.gov (United States)

    Wang, Xiaoxia; Chow, Renee; Deng, Liwen; Anderson, Dan; Weidner, Noel; Godwin, Andrew K; Bewtra, Chanda; Zlotnik, Albert; Bui, Jack; Varki, Ajit; Varki, Nissi

    2011-01-01

    Siglecs (Sialic acid-binding Immunoglobulin Superfamily Lectins) are cell surface signaling receptors of the I-type lectin group that recognize sialic acid-bearing glycans. CD33-related-Siglecs are a subset with expression primarily in cells of hematopoietic origin and functional relevance to immune reactions. Earlier we reported a human-specific gene conversion event that markedly changed the coding region for the extracellular domain of Siglec-11, associated with human-specific expression in microglia (Hayakawa T, Angata T, Lewis AL, Mikkelsen TS, Varki NM, Varki A. 2005. A human-specific gene in microglia. Science. 309:1693). Analyzing human gene microarrays to define new patterns of expression, we observed high levels of SIGLEC11 transcript in the ovary and adrenal cortex. Thus, we examined human and chimpanzee tissues using a well-characterized anti-Siglec-11 mouse monoclonal antibody. Although adrenal expression was variable and confined to infiltrating macrophages in capillaries, ovarian expression of Siglec-11 in both humans and chimpanzees was on fibroblasts, the first example of Siglec expression on mesenchyme-derived stromal cells. Cytokines from such ovarian stromal fibroblasts play important roles in follicle development and ovulation. Stable transfection of SIGLEC11 into a primary human ovarian stromal fibroblast cell line altered the secretion of growth-regulated oncogene α, interleukin (IL)-10, IL-7, transforming growth factor β1 and tumor necrosis factor-α, cytokines involved in ovarian physiology. Probing for Siglec-11 ligands revealed distinct and strong mast cell expression in human ovaries, contrasting to diffuse stromal ligands in chimpanzee ovaries. Interestingly, there was a trend of increased Siglec-11 expression in post-menopausal ovaries compared with pre-menopausal ones. Siglec-11 expression was also found on human ovarian stromal tumors and in polycystic ovarian syndrome, a human-specific disease. These results indicate potential

  11. Physiological expression of the gene for PrP-like protein, PrPLP/Dpl, by brain endothelial cells and its ectopic expression in neurons of PrP-deficient mice ataxic due to Purkinje cell degeneration.

    Science.gov (United States)

    Li, A; Sakaguchi, S; Shigematsu, K; Atarashi, R; Roy, B C; Nakaoke, R; Arima, K; Okimura, N; Kopacek, J; Katamine, S

    2000-11-01

    Recently, a novel gene encoding a prion protein (PrP)-like glycoprotein, PrPLP/Dpl, was identified as being expressed ectopically by neurons of the ataxic PrP-deficient (PRNP(-/-)) mouse lines exhibiting Purkinje cell degeneration. In adult wild-type mice, PrPLP/Dpl mRNA was physiologically expressed at a high level by testis and heart, but was barely detectable in brain. However, transient expression of PrPLP/Dpl mRNA was detectable by Northern blotting in the brain of neonatal wild-type mice, showing maximal expression around 1 week after birth. In situ hybridization paired with immunohistochemistry using anti-factor VIII serum identified brain endothelial cells as expressing the transcripts. Moreover, in the neonatal wild-type mice, the PrPLP/Dpl mRNA colocalized with factor VIII immunoreactivities in spleen and was detectable on capillaries in lamina propria mucosa of gut. These findings suggested a role of PrPLP/Dpl in angiogenesis, in particular blood-brain barrier maturation in the central nervous system. Even in the ataxic Ngsk PRNP(-/-) mice, the physiological regulation of PrPLP/Dpl mRNA expression in brain endothelial cells was still preserved. This strongly supports the argument that the ectopic expression of PrPLP/Dpl in neurons, but not deregulation of its physiological expression in endothelial cells, is involved in the neuronal degeneration in ataxic PRNP(-/-) mice.

  12. Transport phenomena in porous media

    CERN Document Server

    Ingham, Derek B

    1998-01-01

    Research into thermal convection in porous media has substantially increased during recent years due to its numerous practical applications. These problems have attracted the attention of industrialists, engineers and scientists from many very diversified disciplines, such as applied mathematics, chemical, civil, environmental, mechanical and nuclear engineering, geothermal physics and food science. Thus, there is a wealth of information now available on convective processes in porous media and it is therefore appropriate and timely to undertake a new critical evaluation of this contemporary information. Transport Phenomena in Porous Media contains 17 chapters and represents the collective work of 27 of the world's leading experts, from 12 countries, in heat transfer in porous media. The recent intensive research in this area has substantially raised the expectations for numerous new practical applications and this makes the book a most timely addition to the existing literature. It includes recent major deve...

  13. MHD phenomena at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Guenter, S.; Gude, A.; Maraschek, M.; Pinches, S.D.; Sesnic, S.; Wolf, R.C.; Yu, Q.; Zohm, M.

    2001-01-01

    The onset of neoclassical tearing modes leads to the most serious β limit at ASDEX Upgrade. The β p value for the onset of neoclassical tearing modes is found to be proportional to the ion gyro-radius for collisionless plasmas as proposed by the ion polarisation current model. Larger collisionalities have a stabilizing effect. Sawtooth crashes or fishbones can trigger the mode, and in a few cases it appears spontaneously. Fishbones are shown to be able to cause magnetic reconnection. The fractional energy loss due to a (3,2) mode saturates for large pressures at around 25 %. In discharges with large impurity accumulation unusual MHD phenomena such as cascades of high-n tearing modes and modes driven by positive pressure gradients have been found. (author)

  14. MHD phenomena at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Guenter, S.; Gude, A.; Maraschek, M.; Pinches, S.D.; Sesnic, S.; Wolf, R.C.; Yu, Q.; Zohm, H.

    1999-01-01

    The onset of neoclassical tearing modes leads to the most serious β limit at ASDEX Upgrade. The β p value for the onset of neoclassical tearing modes is found to be proportional to the ion gyro-radius for collisionless plasmas as proposed by the ion polarisation current model. Larger collisionalities have a stabilizing effect. Sawtooth crashes or fishbones can trigger the mode, and in a few cases it appears spontaneously. Fishbones are shown to be able to cause magnetic reconnection. The fractional energy loss due to a (3,2) mode saturates for large pressures at around 25%. In discharges with large impurity accumulation unusual MHD phenomena such as cascades of high-n tearing modes and modes driven by positive pressure gradients have been found. (author)

  15. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Martín-García José M.

    2007-12-01

    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term “critical phenomena”. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. Critical phenomena give a natural route from smooth initial data to arbitrarily large curvatures visible from infinity, and are therefore likely to be relevant for cosmic censorship, quantum gravity, astrophysics, and our general understanding of the dynamics of general relativity.

  16. Emergent Phenomena at Oxide Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H.Y.

    2012-02-16

    Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burst of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the

  17. The quest for new phenomena

    International Nuclear Information System (INIS)

    Hinchliffe, I.

    1996-12-01

    The Standard Model of particle physics has been very successful in describing experimental data with great precision. With the exception of some neutrino anomalies, there is no data that is in disagreement with it. Nevertheless, the model is regarded as incomplete and unsatisfactory. There is no explanation of the pattern of quark and lepton masses and, possibly more important, no understanding of the scale of electroweak interactions. Electroweak symmetry breaking is implemented in the Standard Model from the presence of a scalar electroweak doublet, the Higgs field, that acquires a vacuum expectation value of order 250 GeV and leaves as a remnant one physical state, the electrically neutral Higgs boson whose mass is not predicted. In this talk, the author compares the techniques used at, and capabilities of, various facilities in searching for new phenomena. The author emphasizes the cases where information from more than one facility may be needed to fully explore the physics

  18. In-vessel phenomena -- CORA

    International Nuclear Information System (INIS)

    Ott, L.J.; Rij, W.I. van.

    1991-01-01

    Experiment-specific models have been employed since 1986 by Oak Ridge National Laboratory (ORNL) severe accident analysis programs for the purpose of boiling water reactor experimental planning and optimum interpretation of experimental results. The large integral tests performed to date, which start from an initial undamaged core state, have involved significantly different-from-prototypic boundary and experimental conditions because of either normal facility limitations or specific experimental constraints. These experiments (ACRR: DF-4, NRU: FLHT-6, and CORA) were designed to obtain specific phenomenological information such as the degradation and interaction of prototypic components and the effects on melt progression of control-blade materials and channel boxes. Applications of ORNL models specific to the KfK CORA-16 and CORA-17 experiments are discussed and significant findings from the experimental analyses such as the following are presented: applicability of available Zircaloy oxidation kinetics correlations; influence of cladding strain on Zircaloy oxidation; influence of spacer grids on the structural heatup; and the impact of treating the gaseous coolant as a gray interacting medium. The experiment-specific models supplement and support the systems-level accident analysis codes. They allow the analyst to accurately quantify the observed experimental phenomena and to compensate for the effect of known uncertainties. They provide a basis for the efficient development of new models for phenomena that are currently not modeled (such as material interactions). They can provide validated phenomenological models (from the results of the experiments) as candidates for incorporation in the systems-level ''whole-core'' codes

  19. Remote sensing of natural phenomena

    Directory of Open Access Journals (Sweden)

    Miodrag D. Regodić

    2014-06-01

    Full Text Available There has always been a need to directly perceive and study the events whose extent is beyond people's possibilities. In order to get new data and to make observations and studying much more objective in comparison with past syntheses - a new method of examination called remote sensing has been adopted. The paper deals with the principles and elements of remote sensing, as well as with the basic aspects of using remote research in examining meteorological (weather parameters and the conditions of the atmosphere. The usage of satellite images is possible in all phases of the global and systematic research of different natural phenomena when airplane and satellite images of different characteristics are used and their analysis and interpretation is carried out by viewing and computer added procedures. Introduction Remote sensing of the Earth enables observing and studying global and local events that occur on it. Satellite images are nowadays used in geology, agriculture, forestry, geodesy, meteorology, spatial and urbanism planning, designing of infrastructure and other objects, protection from natural and technological catastrophes, etc. It it possible to use satellite images in all phases of global and systematic research of different natural phenomena. Basics of remote sensing Remote sensing is a method of the acquisition and interpretation of information about remote objects without making a physical contact with them. The term Daljinska detekcija is a literal translation of the English term Remote Sensing. In French it isTeledetection, in German - Fernerkundung, in Russian - дистанционие иследования. We also use terms such as: remote survailance, remote research, teledetection, remote methods, and distance research. The basic elements included in Remote Sensing are: object, electromagnetic energy, sensor, platform, image, analysis, interpretation and the information (data, fact. Usage of satellite remote research in

  20. The age-dependent epigenetic and physiological changes in an Arabidopsis T87 cell suspension culture during long-term cultivation

    International Nuclear Information System (INIS)

    Kwiatkowska, Aleksandra; Zebrowski, Jacek; Oklejewicz, Bernadetta; Czarnik, Justyna; Halibart-Puzio, Joanna; Wnuk, Maciej

    2014-01-01

    Highlights: • A decrease in proliferation rate during long-term cultivation of Arabidopsis cells. • Age-dependent increase in senescence-associated gene expression in Arabidopsis cells. • Age-related increase in DNA methylation, H3K9me2, and H3K27me3 in Arabidopsis cells. • High potential of photosynthetic efficiency of long-term cultured Arabidopsis cells. - Abstract: Plant cell suspension cultures represent good model systems applicable for both basic research and biotechnological purposes. Nevertheless, it is widely known that a prolonged in vitro cultivation of plant cells is associated with genetic and epigenetic instabilities, which may limit the usefulness of plant lines. In this study, the age-dependent epigenetic and physiological changes in an asynchronous Arabidopsis T87 cell culture were examined. A prolonged cultivation period was found to be correlated with a decrease in the proliferation rate and a simultaneous increase in the expression of senescence-associated genes, indicating that the aging process started at the late growth phase of the culture. In addition, increases in the heterochromatin-specific epigenetic markers, i.e., global DNA methylation, H3K9 dimethylation, and H3K27 trimethylation, were observed, suggesting the onset of chromatin condensation, a hallmark of the early stages of plant senescence. Although the number of live cells decreased with an increase in the age of the culture, the remaining viable cells retained a high potential to efficiently perform photosynthesis and did not exhibit any symptoms of photosystem II damage

  1. Occupational physiology

    CERN Document Server

    Toomingas, Allan; Tornqvist, Ewa Wigaeus

    2011-01-01

    In a clear and accessible presentation, Occupational Physiology focuses on important issues in the modern working world. Exploring major public health problems-such as musculoskeletal disorders and stress-this book explains connections between work, well-being, and health based on up-to-date research in the field. It provides useful methods for risk assessment and guidelines on arranging a good working life from the perspective of the working individual, the company, and society as a whole.The book focuses on common, stressful situations in different professions. Reviewing bodily demands and r

  2. Increased leaf mesophyll porosity following transient retinoblastoma-related protein silencing is revealed by microcomputed tomography imaging and leads to a system-level physiological response to the altered cell division pattern.

    Science.gov (United States)

    Dorca-Fornell, Carmen; Pajor, Radoslaw; Lehmeier, Christoph; Pérez-Bueno, Marísa; Bauch, Marion; Sloan, Jen; Osborne, Colin; Rolfe, Stephen; Sturrock, Craig; Mooney, Sacha; Fleming, Andrew

    2013-12-01

    The causal relationship between cell division and growth in plants is complex. Although altered expression of cell-cycle genes frequently leads to altered organ growth, there are many examples where manipulation of the division machinery leads to a limited outcome at the level of organ form, despite changes in constituent cell size. One possibility, which has been under-explored, is that altered division patterns resulting from manipulation of cell-cycle gene expression alter the physiology of the organ, and that this has an effect on growth. We performed a series of experiments on retinoblastoma-related protein (RBR), a well characterized regulator of the cell cycle, to investigate the outcome of altered cell division on leaf physiology. Our approach involved combination of high-resolution microCT imaging and physiological analysis with a transient gene induction system, providing a powerful approach for the study of developmental physiology. Our investigation identifies a new role for RBR in mesophyll differentiation that affects tissue porosity and the distribution of air space within the leaf. The data demonstrate the importance of RBR in early leaf development and the extent to which physiology adapts to modified cellular architecture resulting from altered cell-cycle gene expression. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  3. Mesoscopic Modeling of Multiphysicochemical Transport Phenomena in Porous Media

    Directory of Open Access Journals (Sweden)

    Qinjun Kang

    2010-01-01

    Full Text Available We present our recent progress on mesoscopic modeling of multiphysicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO2-saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occurring at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multiphysicochemical processes in various energy, earth, and environmental systems.

  4. Teaching Cardiovascular Physiology with Equivalent Electronic Circuits in a Practically Oriented Teaching Module

    Science.gov (United States)

    Ribaric, Samo; Kordas, Marjan

    2011-01-01

    Here, we report on a new tool for teaching cardiovascular physiology and pathophysiology that promotes qualitative as well as quantitative thinking about time-dependent physiological phenomena. Quantification of steady and presteady-state (transient) cardiovascular phenomena is traditionally done by differential equations, but this is time…

  5. Spontaneous T Cell Proliferation: A Physiologic Process to Create and Maintain Homeostatic Balance and Diversity of the Immune System

    Science.gov (United States)

    Min, Booki

    2018-01-01

    Naive T lymphocytes undergo heterogeneous proliferative responses when introduced into lymphopenic hosts, referred to as “homeostatic proliferation” and “spontaneous proliferation.” Spontaneous proliferation is a unique process through which the immune system generates memory phenotype cells with increasing T cell receptors repertoire complexity. Here, the mechanisms that initiate and control spontaneous proliferation are discussed. PMID:29616038

  6. Metabolic profiling and flux analysis of MEL-2 human embryonic stem cells during exponential growth at physiological and atmospheric oxygen concentrations.

    Directory of Open Access Journals (Sweden)

    Jennifer Turner

    Full Text Available As human embryonic stem cells (hESCs steadily progress towards regenerative medicine applications there is an increasing emphasis on the development of bioreactor platforms that enable expansion of these cells to clinically relevant numbers. Surprisingly little is known about the metabolic requirements of hESCs, precluding the rational design and optimisation of such platforms. In this study, we undertook an in-depth characterisation of MEL-2 hESC metabolic behaviour during the exponential growth phase, combining metabolic profiling and flux analysis tools at physiological (hypoxic and atmospheric (normoxic oxygen concentrations. To overcome variability in growth profiles and the problem of closing mass balances in a complex environment, we developed protocols to accurately measure uptake and production rates of metabolites, cell density, growth rate and biomass composition, and designed a metabolic flux analysis model for estimating internal rates. hESCs are commonly considered to be highly glycolytic with inactive or immature mitochondria, however, whilst the results of this study confirmed that glycolysis is indeed highly active, we show that at least in MEL-2 hESC, it is supported by the use of oxidative phosphorylation within the mitochondria utilising carbon sources, such as glutamine to maximise ATP production. Under both conditions, glycolysis was disconnected from the mitochondria with all of the glucose being converted to lactate. No difference in the growth rates of cells cultured under physiological or atmospheric oxygen concentrations was observed nor did this cause differences in fluxes through the majority of the internal metabolic pathways associated with biogenesis. These results suggest that hESCs display the conventional Warburg effect, with high aerobic activity despite high lactate production, challenging the idea of an anaerobic metabolism with low mitochondrial activity. The results of this study provide new insight that

  7. Reminiscing about Jan Evangelista Purkinje: a pioneer of modern experimental physiology.

    Science.gov (United States)

    Cavero, Icilio; Guillon, Jean-Michel; Holzgrefe, Henry H

    2017-12-01

    This article reminisces about the life and key scientific achievements of Jan Evangelista Purkinje (1787-1869), a versatile 19th century Czech pioneer of modern experimental physiology. In 1804, after completing senior high school, Purkinje joined the Piarist monk order, but, after a 3-yr novitiate, he gave up the religious calling "to deal more freely with science." In 1818, he earned a Medical Doctor degree from Prague University by defending a dissertation on intraocular phenomena observed in oneself. In 1823, Purkinje became a Physiology and Pathology professor at the Prussian Medical University in Breslau, where he innovated the traditional teaching methods of physiology. Purkinje's contributions to physiology were manifold: accurate descriptions of various visual phenomena (e.g., Purkinje-Sanson images, Purkinje phenomenon), discovery of the terminal network of the cardiac conduction system (Purkinje fibers), identification of cerebellar neuronal bodies (Purkinje cells), formulation of the vertigo law (Purkinje's law), discovery of criteria to classify human fingerprints, etc. In 1850, Purkinje accepted and held until his death the Physiology chair at Prague Medical Faculty. During this period, he succeeded in introducing the Czech idiom (in addition to long-established German and Latin) as a Medical Faculty teaching language. Additionally, as a zealous Czech patriot, he actively contributed to the naissance and consolidation of a national Czech identity conscience. Purkinje was a trend-setting scientist who, throughout his career, worked to pave the way for the renovation of physiology from a speculative discipline, ancilla of anatomy, into a factual, autonomous science committed to the discovery of mechanisms governing in-life functions. Copyright © 2017 the American Physiological Society.

  8. Intraoperative engineering of osteogenic grafts combining freshly harvested, human adipose-derived cells and physiological doses of bone morphogenetic protein-2

    Directory of Open Access Journals (Sweden)

    A Mehrkens

    2012-09-01

    Full Text Available Engineered osteogenic constructs for bone repair typically involve complex and costly processes for cell expansion. Adipose tissue includes mesenchymal precursors in large amounts, in principle allowing for an intraoperative production of osteogenic grafts and their immediate implantation. However, stromal vascular fraction (SVF cells from adipose tissue were reported to require a molecular trigger to differentiate into functional osteoblasts. The present study tested whether physiological doses of recombinant human BMP-2 (rhBMP-2 could induce freshly harvested human SVF cells to generate ectopic bone tissue. Enzymatically dissociated SVF cells from 7 healthy donors (1 x 106 or 4 x 106 were immediately embedded in a fibrin gel with or without 250 ng rhBMP-2, mixed with porous silicated calcium-phosphate granules (Actifuse®, Apatech (final construct size: 0.1 cm3 and implanted ectopically for eight weeks in nude mice. In the presence of rhBMP-2, SVF cells not only supported but directly contributed to the formation of bone ossicles, which were not observed in control cell-free, rhBMP-2 loaded implants. In vitro analysis indicated that rhBMP-2 did not involve an increase in the percentage of SVF cells recruited to the osteogenic lineage, but rather induced a stimulation of the osteoblastic differentiation of the committed progenitors. These findings confirm the feasibility of generating fully osteogenic grafts using an easily accessible autologous cell source and low amounts of rhBMP-2, in a timing compatible with an intraoperative schedule. The study warrants further investigation at an orthotopic site of implantation, where the delivery of rhBMP-2 could be bypassed thanks to the properties of the local milieu.

  9. Immune modulating effects of NKT cells in a physiologically low dose Leishmania major infection model after αGalCer analog PBS57 stimulation.

    Directory of Open Access Journals (Sweden)

    Klaus G Griewank

    2014-06-01

    Full Text Available Leishmaniasis is a parasitic infection affecting ∼12 million people worldwide, mostly in developing countries. Treatment options are limited and no effective vaccines exist to date. Natural Killer T (NKT cells are a conserved innate-like lymphocyte population with immunomodulating effects in various settings. A number of reports state a role of NKT cells in different models of Leishmania infection. Here, we investigated the effect of NKT cells in a physiologically relevant, intradermal low dose infection model. After inoculation of 103 infectious-stage L. major, comparable numbers of skin-immigrating NKT cells in both susceptible BALB/c mice and resistant C57BL/6 mice were noted. Compared to their wild type counterparts, NKT cell-deficient mice on a C57BL/6 background were better able to contain infection with L. major and showed decreased IL-4 production in cytokine analysis performed 5 and 8 weeks after infection. Low doses of the NKT cell stimulating αGalCer analog PBS57 applied at the time of infection led to disease exacerbation in C57BL/6 wild-type, but not NKT-deficient mice. The effect was dependent both on the timing and amount of PBS57 administered. The effect of NKT cell stimulation by PBS57 proved to be IL-4 dependent, as it was neutralized in IL-4-deficient C57BL/6 or anti-IL-4 antibody-treated wild-type mice. In contrast to C57BL/6 mice, administration of PBS57 in susceptible BALB/c mice resulted in an improved course of disease. Our results reveal a strain- and cytokine-dependent regulatory role of NKT cells in the development of immunity to low dose L. major infections. These effects, probably masked in previous studies using higher parasite inocula, should be considered in future therapy and immunization approaches.

  10. Immune modulating effects of NKT cells in a physiologically low dose Leishmania major infection model after αGalCer analog PBS57 stimulation.

    Science.gov (United States)

    Griewank, Klaus G; Lorenz, Beate; Fischer, Michael R; Boon, Louis; Lopez Kostka, Susanna; von Stebut, Esther

    2014-06-01

    Leishmaniasis is a parasitic infection affecting ∼12 million people worldwide, mostly in developing countries. Treatment options are limited and no effective vaccines exist to date. Natural Killer T (NKT) cells are a conserved innate-like lymphocyte population with immunomodulating effects in various settings. A number of reports state a role of NKT cells in different models of Leishmania infection. Here, we investigated the effect of NKT cells in a physiologically relevant, intradermal low dose infection model. After inoculation of 103 infectious-stage L. major, comparable numbers of skin-immigrating NKT cells in both susceptible BALB/c mice and resistant C57BL/6 mice were noted. Compared to their wild type counterparts, NKT cell-deficient mice on a C57BL/6 background were better able to contain infection with L. major and showed decreased IL-4 production in cytokine analysis performed 5 and 8 weeks after infection. Low doses of the NKT cell stimulating αGalCer analog PBS57 applied at the time of infection led to disease exacerbation in C57BL/6 wild-type, but not NKT-deficient mice. The effect was dependent both on the timing and amount of PBS57 administered. The effect of NKT cell stimulation by PBS57 proved to be IL-4 dependent, as it was neutralized in IL-4-deficient C57BL/6 or anti-IL-4 antibody-treated wild-type mice. In contrast to C57BL/6 mice, administration of PBS57 in susceptible BALB/c mice resulted in an improved course of disease. Our results reveal a strain- and cytokine-dependent regulatory role of NKT cells in the development of immunity to low dose L. major infections. These effects, probably masked in previous studies using higher parasite inocula, should be considered in future therapy and immunization approaches.

  11. Poorly studied phenomena in geoelectrics

    Directory of Open Access Journals (Sweden)

    В. С. Могилатов

    2016-12-01

    Full Text Available Undoubtedly, modern geoelectric technologies emerge in the result of the development of traditional approaches and techniques. However of more interest is the appearance of completely new technologies based on new effects and new models of interaction of geological medium and electromagnetic field. The author does not commit to indicate principally new directions, but only wants to discuss some poorly known facts from the theory and practice of geoelectrics. The outcome of this study could be considered attracting the attention of experts to non-traditional signals in geoelectrics. The reviewed phenomena of interest, not fully implemented in practice in the author’s opinion, are field split into two polarizations: transverse electric (the ТЕ-field and transverse magnetic (the ТМ-field, then some poorly known properties of ТМ-field, the role of bias currents, the anisotropy of horizontal resistances, the role of geomagnetic field in geoelectric sounding, the unique resolution of CSEM (Controlled Source Electro-Magnetic techniques at sea.

  12. Understanding empathy and related phenomena.

    Science.gov (United States)

    Shamasundar, C

    1999-01-01

    Over a period of time, the author arrived at a few tentative postulates concerning empathy and related processes based on some of his experiences and observations. The central theme of these postulates is, firstly, that interpersonal interaction is an interaction of the personal-space fields. Secondly, empathy, therapeutic benefit, and the professional stress are all related to the same process of interpersonal interaction. This interaction takes place as an enmeshment of personal spaces of the interacting individuals, and involves transfer of a wide range of information in the affective, cognitive, and other areas. This is because the personal spaces have fieldlike qualities analogous to what Kurt Lewin described. Thus, such phenomena as empathy, therapeutic benefit, professional stress are all consequences of the same process. It is possible to substantiate these postulates by diverse evidences in the published literature. The natural consequences of such an interpersonal interaction are empathic understanding, transfer of mood states (like hope, distress or expectancy), affective states (like anxiety, sadness, anger or hostility), ideas, images and even attitudes and values, etc. This phenomenon of transfer can explain such processes as therapeutic benefit in individual and group settings, professional stress, shared delusions, and even experimenter bias. Whether one becomes aware of such transferred information or not depends upon the intent and sensitivity of the participants.

  13. Conductance phenomena in microcrystalline cellulose

    Science.gov (United States)

    Nilsson, M.

    2006-02-01

    We have investigated the conduction phenomena in compacted tablets of cellulose with varying relative humidity (RH) with techniques such as Low Frequency Dielectric Spectroscopy (LFDS) and Transient Current (TC) at room temperature. Two exponential decaying regions in the transient current measurements indicate two ionic species contributing to the conduction mechanism. A high power-law exponent of 9 for the conductance with moisture content has been found. The mobility initially decreases with RH up to monolayer coverage, and further water vapor increases the mobility, indicating a blocking of available positions for the charge carrier ions. When the amount of water molecules present in the tablet increases one order of magnitude, the number of charge carriers increases 5-6 orders of magnitude, suggesting a transition from a power-law increase to a linear effective medium theory for the conduction. The charge carrier dependence on RH suggests that a percolating network of water molecules adsorbed to 6-OH units on the cellulose chain span through the sample. The conductivity mechanisms in cellulose are still not clear.

  14. Mixed Fluid Conditions: Capillary Phenomena

    KAUST Repository

    Santamarina, Carlos

    2017-07-06

    Mixed fluid phenomena in porous media have profound implications on soil-atmosphere interaction, energy geotechnology, environmental engineering and infrastructure design. Surface tension varies with pressure, temperature, solute concentration, and surfactant concentration; on the other hand, the contact angle responds to interfacial tensions, surface topography, invasion velocity, and chemical interactions. Interfaces are not isolated but interact through the fluid pressure and respond to external fields. Jumps, snap-offs and percolating wetting liquids along edges and crevices are ubiquitous in real, non-cylindrical porous networks. Pore- and macroscale instabilities together with pore structure variability-and-correlation favor fluid trapping and hinder recovery efficiency. The saturation-pressure characteristic curve is affected by the saturation-history, flow-rate, the mechanical response of the porous medium, and time-dependent reactive and diffusive processes; in addition, there are salient differences between unsaturation by internal gas nucleation and gas invasion. Capillary forces add to other skeletal forces in the porous medium and can generate open-mode discontinuities when the capillary entry pressure is high relative to the effective stress. Time emerges as an important variable in mixed-fluid conditions and common quasi-static analyses may fail to capture the system response.

  15. In vivo Whole-Cell Recordings Combined with Electron Microscopy Reveal Unexpected Morphological and Physiological Properties in the Lateral Nucleus of the Trapezoid Body in the Auditory Brainstem.

    Science.gov (United States)

    Franken, Tom P; Smith, Philip H; Joris, Philip X

    2016-01-01

    The lateral nucleus of the trapezoid body (LNTB) is a prominent nucleus in the superior olivary complex in mammals including humans. Its physiology in vivo is poorly understood due to a paucity of recordings. It is thought to provide a glycinergic projection to the medial superior olive (MSO) with an important role in binaural processing and sound localization. We combined in vivo patch clamp recordings with labeling of individual neurons in the Mongolian gerbil. Labeling of the recorded neurons allowed us to relate physiological properties to anatomy at the light and electron microscopic level. We identified a population of quite dorsally located neurons with surprisingly large dendritic trees on which most of the synaptic input impinges. In most neurons, one or more of these dendrites run through and are then medial to the MSO. These neurons were often binaural and could even show sensitivity to interaural time differences (ITDs) of stimulus fine structure or envelope. Moreover, a subpopulation showed enhanced phase-locking to tones delivered in the tuning curve tail. We propose that these neurons constitute the gerbil main LNTB (mLNTB). In contrast, a smaller sample of neurons was identified that was located more ventrally and that we designate to be in posteroventral LNTB (pvLNTB). These cells receive large somatic excitatory terminals from globular bushy cells. We also identified previously undescribed synaptic inputs from the lateral superior olive. pvLNTB neurons are usually monaural, display a primary-like-with-notch response to ipsilateral short tones at CF and can phase-lock to low frequency tones. We conclude that mLNTB contains a population of neurons with extended dendritic trees where most of the synaptic input is found, that can show enhanced phase-locking and sensitivity to ITD. pvLNTB cells, presumed to provide glycinergic input to the MSO, get large somatic globular bushy synaptic inputs and are typically monaural with short tone responses similar

  16. Alkanols and chlorophenols cause different physiological adaptive responses on the level of cell surface properties and membrane vesicle formation in Pseudomonas putida DOT-T1E.

    Science.gov (United States)

    Baumgarten, Thomas; Vazquez, José; Bastisch, Christian; Veron, Wilfried; Feuilloley, Marc G J; Nietzsche, Sandor; Wick, Lukas Y; Heipieper, Hermann J

    2012-01-01

    In order to cope with the toxicity imposed by the exposure to environmental hydrocarbons, many bacteria have developed specific adaptive responses such as modifications in the cell envelope. Here we compared the influence of n-alkanols and chlorophenols on the surface properties of the solvent-tolerant bacterium Pseudomonas putida DOT-T1E. In the presence of toxic concentrations of n-alkanols, this strain significantly increased its cell surface charge and hydrophobicity with changes depending on the chain length of the added n-alkanols. The adaptive response occurred within 10 min after the addition of the solvent and was demonstrated to be of physiological nature. Contrary to that, chlorophenols of similar hydrophobicity and potential toxicity as the corresponding alkanols caused only minor effects in the surface properties. To our knowledge, this is the first observation of differences in the cellular adaptive response of bacteria to compound classes of quasi equal hydrophobicity and toxicity. The observed adaptation of the physico-chemical surface properties of strain DOT-T1E to the presence of alkanols was reversible and correlated with changes in the composition of the lipopolysaccharide content of the cells. The reaction is explained by previously described reactions allowing the release of membrane vesicles that was demonstrated for cells affected by 1-octanol and heat shock, whereas no membrane vesicles were released after the addition of chlorophenols.

  17. Physiological, molecular and ultrastructural analyses during ripening and over-ripening of banana (Musa spp., AAA group, Cavendish sub-group) fruit suggest characteristics of programmed cell death.

    Science.gov (United States)

    Ramírez-Sánchez, Maricruz; Huber, Donald J; Vallejos, C Eduardo; Kelley, Karen

    2018-01-01

    Programmed cell death (PCD) is a part of plant development that has been studied for petal senescence and vegetative tissue but has not been thoroughly investigated for fleshy fruits. The purpose of this research was to examine ripening and over-ripening in banana fruit to determine if there were processes in common to previously described PCD. Loss of cellular integrity (over 40%) and development of senescence related dark spot (SRDS) occurred after day 8 in banana peel. Nuclease and protease activity in the peel increased during ripening starting from day 2, and decreased during over-ripening. The highest activity was for proteases and nucleases with apparent molecular weights of 86 kDa and 27 kDa, respectively. Images of SRDS showed shrinkage of the upper layers of cells, visually suggesting cell death. Decrease of electron dense areas was evident in TEM micrographs of nuclei. This study shows for the first time that ripening and over-ripening of banana peel share physiological and molecular processes previously described in plant PCD. SRDS could represent a morphotype of PCD that characterizes a structural and biochemical failure in the upper layers of the peel, thereafter spreading to lower and adjacent layers of cells. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  18. Observation of Celestial Phenomena in Ancient China

    Science.gov (United States)

    Sun, Xiaochun

    Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

  19. [A Method for Protein Photo-cross-linking in Living Cells Facilitating Analysis of Physiological Interactions of Proteins].

    Science.gov (United States)

    Hino, Nobumasa

    2015-01-01

    In living cells, most proteins form complexes with other proteins to exert their functions. Since protein functions are regulated in response to changes in the cellular environment, the components of the complexes can vary; therefore, proteins often interact in a weak and transient manner. To capture such labile protein interactions, we have developed a method for photo-cross-linking of proteins directly interacting in mammalian cells; this method involves expansion of the genetic code and site-specific incorporation of photoreactive amino acids into proteins. Upon cross-linking, protein complexes are stabilized by a covalent bond and can be readily isolated from cell extracts without the problems usually associated with simple affinity purification methods such as co-immunoprecipitation. Photo-cross-linkers have another benefit: they react exclusively with molecules within a range defined by the linker length. This property becomes useful for determining the binding interface of two proteins because the linkers can be introduced in a site-directed manner with our method. In this review, we first describe the expansion of the genetic code of mammalian cells for the incorporation of non-natural amino acids into proteins. Then, we introduce our recent applications and developments of the cross-linking method: identification of intracellular binding partners of the signaling protein growth factor receptor binding protein 2; analysis of the binding between membrane proteins on the cell surface; and a novel photoreactive amino acid that enables wide-ranging photo-cross-linking.

  20. Comparative study of hematopoietic stem and progenitor cells between sexes in mice under physiological conditions along time.

    Science.gov (United States)

    Gasco, Samanta; Rando, Amaya; Zaragoza, Pilar; García-Redondo, Alberto; Calvo, Ana Cristina; Osta, Rosario

    2017-12-01

    Hematopoietic stem and progenitor cells (HSPCs) are attractive targets in regenerative medicine, although the differences in their homeostatic maintenance between sexes along time are still under debate. We accurately monitored hematopoietic stem cells (HSCs), common lymphoid progenitors (CLPs), and common myeloid progenitors (CMPs) frequencies by flow cytometry, by performing serial peripheral blood extractions from male and female B6SJL wild-type mice and found no significant differences. Only modest differences were found in the gene expression profile of Slamf1 and Gata2. Our findings suggest that both sexes could be used indistinctly to perform descriptive studies in the murine hematopoietic system, especially for flow cytometry studies in peripheral blood. This would allow diminishing the number of animals needed for the experimental procedures. In addition, the use of serial extractions in the same animals drastically decreases the number of animals needed. © 2017 International Federation for Cell Biology.

  1. Gravitational physiology of human immune cells: a review of in vivo, ex vivo and in vitro studies

    Science.gov (United States)

    Cogoli, A.

    1996-01-01

    The study of the function of immune cells in microgravity has been studied for more than 20 years in several laboratories. It is clear today that the immune system is depressed in more than 50% of the astronauts during and after space flight and that the activation of T lymphocytes by mitogens in vitro changes dramatically. This article gives an overview of the gravitational studies conducted by our laboratory in Spacelab, in MIR station, in sounding rockets and on the ground in the clinostat and the centrifuge. Three experimental approaches are followed in our work: (i) Ex vivo studies are performed with blood samples drawn from astronauts; (ii) in vivo studies are based on the application of seven antigens to the skin of the astronauts; (iii) in vitro studies are carried out with immune cells purified from the blood of healthy donors (not astronauts). The data from our in vivo and ex vivo studies are in agreement with those of other laboratories and show that the immunological function is depressed in the majority of astronauts as a consequence of the stress of space flight rather than by a direct influence of gravity on the cell. Immune depression may become a critical hazard on long duration flights on space stations or to other planets. In vitro experiments show that cultures of free-floating lymphocytes and monocytes undergo a dramatic depression of activation by the mitogen concanavalin A, while activation is more than doubled when the cells are attached to microcarrier beads. Such effects may be attributed to both direct and indirect effects of gravitational unloading on basic biological mechanisms of the cell. While the in vitro data are very important to clarify certain aspects of the biological mechanism of T cells activation, they are not descriptive of the changes of the immunological function of the astronauts.

  2. Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2

    Directory of Open Access Journals (Sweden)

    Giovanni eSandrini

    2015-05-01

    Full Text Available Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7 fold increase of the cyanobacterial biomass and ~2.5 fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4,691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes.

  3. Starting physiology: bioelectrogenesis.

    Science.gov (United States)

    Baptista, Vander

    2015-12-01

    From a Cartesian perspective of rational analysis, the electric potential difference across the cell membrane is one of the fundamental concepts for the study of physiology. Unfortunately, undergraduate students often struggle to understand the genesis of this energy gradient, which makes the teaching activity a hard task for the instructor. The topic of bioelectrogenesis encompasses multidisciplinary concepts, involves several mechanisms, and is a dynamic process, i.e., it never turns off during the lifetime of the cell. Therefore, to improve the transmission and acquisition of knowledge in this field, I present an alternative didactic model. The design of the model assumes that it is possible to build, in a series of sequential steps, an assembly of proteins within the membrane of an isolated cell in a simulated electrophysiology experiment. Initially, no proteins are inserted in the membrane and the cell is at a baseline energy state; the extracellular and intracellular fluids are at thermodynamic equilibrium. Students are guided through a sequence of four steps that add key membrane transport proteins to the model cell. The model is simple at the start and becomes progressively more complex, finally producing transmembrane chemical and electrical gradients. I believe that this didactic approach helps instructors with a more efficient tool for the teaching of the mechanisms of resting membrane potential while helping students avoid common difficulties that may be encountered when learning this topic. Copyright © 2015 The American Physiological Society.

  4. Collection and storage of red blood cells with anticoagulant and additive solution with a physiologic pH

    NARCIS (Netherlands)

    Burger, Patrick; Korsten, Herbert; Verhoeven, Arthur J.; de Korte, Dirk; van Bruggen, Robin

    2012-01-01

    BACKGROUND: A donation of whole blood is most commonly collected in acidic citrate-phosphate-dextrose (CPD) variants with pH 5.2 to 6.2 as anticoagulants. Previously, we have shown that the initial pH after red blood cell (RBC) preparation can have an effect on RBCs during storage. First, we

  5. Effect of eggshell temperature and a hole in the air cell on the perinatal development and physiology of layer hatchlings

    NARCIS (Netherlands)

    Molenaar, R.; Vries, de S.; Anker, van den I.; Meijerhof, R.; Kemp, B.; Brand, van den H.

    2010-01-01

    To investigate the effect of incubation conditions on layer hatchlings, an experiment was performed in which layer eggs were incubated at a normal (37.8°C) or high (38.9°C) eggshell temperature (EST) and a hole was punctured in the air cell of half of the eggs in both EST treatments from d 14 of

  6. Multiple Regulatory Roles of the Mouse Transmembrane Adaptor Protein NTAL in Gene Transcription and Mast Cell Physiology

    Czech Academy of Sciences Publication Activity Database

    Polakovičová, Iva; Dráberová, Lubica; Šimíček, Michal; Dráber, Petr

    2014-01-01

    Roč. 9, č. 8 (2014), e105539 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GBP302/12/G101; GA MŠk LD12073 Institutional support: RVO:68378050 Keywords : mast cells * NTAL * microarray gene-expression profiling * spreading * chemotaxis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.234, year: 2014

  7. Physiological and cell morphology adaptation of Bacillus subtilis at near-zero specific growth rates: a transcriptome analysis.

    Science.gov (United States)

    Overkamp, Wout; Ercan, Onur; Herber, Martijn; van Maris, Antonius J A; Kleerebezem, Michiel; Kuipers, Oscar P

    2015-02-01

    Nutrient scarcity is a common condition in nature, but the resulting extremely low growth rates (below 0.025 h(-1) ) are an unexplored research area in Bacillus subtilis. To understand microbial life in natural environments, studying the adaptation of B. subtilis to near-zero growth conditions is relevant. To this end, a chemostat modified for culturing an asporogenous B. subtilis sigF mutant strain at extremely low growth rates (also named a retentostat) was set up, and biomass accumulation, culture viability, metabolite production and cell morphology were analysed. During retentostat culturing, the specific growth rate decreased to a minimum of 0.00006 h(-1) , corresponding to a doubling time of 470 days. The energy distribution between growth and maintenance-related processes showed that a state of near-zero growth was reached. Remarkably, a filamentous cell morphology emerged, suggesting that cell separation is impaired under near-zero growth conditions. To evaluate the corresponding molecular adaptations to extremely low specific growth, transcriptome changes were analysed. These revealed that cellular responses to near-zero growth conditions share several similarities with those of cells during the stationary phase of batch growth. However, fundamental differences between these two non-growing states are apparent by their high viability and absence of stationary phase mutagenesis under near-zero growth conditions. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. Space Physiology within an Exercise Physiology Curriculum

    Science.gov (United States)

    Carter, Jason R.; West, John B.

    2013-01-01

    Compare and contrast strategies remain common pedagogical practices within physiological education. With the support of an American Physiological Society Teaching Career Enhancement Award, we have developed a junior- or senior-level undergraduate curriculum for exercise physiology that compares and contrasts the physiological adaptations of…

  9. Physiological and clinically attainable concentrations of 1,25-dihydroxyvitamin D3 suppress proliferation and extracellular matrix protein expression in mouse pancreatic stellate cells.

    Science.gov (United States)

    Bläuer, Merja; Sand, Juhani; Laukkarinen, Johanna

    2015-01-01

    Vitamin D is an antiproliferative and differentiation-promoting secosteroid hormone with pleiotropic homeostatic functions in bone and extraskeletal tissues. Signaling of vitamin D is mediated via its ubiquitously expressed nuclear receptor, the vitamin D receptor (VDR). Pancreatic stellate cells have recently been identified as targets of vitamin D action. Our aim was to elucidate the effectiveness of the most potent endogenous vitamin D metabolite, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the proliferation and extracellular matrix (ECM) protein expression in pancreatic stellate cells (PSCs) using concentrations of the compound from the physiological and clinically attainable range in humans. Culture-activated mouse PSCs were exposed to 1,25(OH)2D3 concentrations ranging from 0.1 nM to 10 nM for 7 days and subjected to colorimetric crystal violet assay for cell growth assessment and to Western blot and immunohistochemical analyses of VDR, fibronectin and collagen I using protein-specific antibodies. Immunohistochemical localization of VDR was performed on mouse pancreatic tissue and on a set of human specimens obtained at pancreatic surgery. A low basal level of VDR was detected in PSCs that was strongly induced in the presence of ligand. Cell growth was suppressed dose-dependently by 1,25(OH)2D3, the mean percentages of inhibition ranging from 24% at the physiological 0.1 nM concentration to around 60% at 10 nM. Significant 48% and 40% reductions in fibronectin expression were seen at 0.5 nM and 1 nM 1,25(OH)2D3. A minor decrease in collagen I expression was detected at 5 nM. VDR was predominantly localized in the islets of Langerhans in mouse and human tissues. In the latter VDR was expressed also in the exocrine tissue showing individual variation in its cellular distribution. Mouse PSCs express VDR protein and are sensitive 1,25(OH)2D3 target cells with low levels of 1,25(OH)2D3 exerting antiproliferative and antifibrotic effects on activated PSCs in

  10. Swimming physiology.

    Science.gov (United States)

    Holmér, I

    1992-05-01

    Swimming takes place in a medium, that presents different gravitational and resistive forces, respiratory conditions and thermal stress compared to air. The energy cost of propulsion in swimming is high, but a considerable reduction occurs at a given velocity as result of regular swim training. In medley swimmers the energy cost is lowest for front crawl, followed by backstroke, butterfly and breast-stroke. Cardiac output is probably not limiting for performance since swimmers easily achieve higher values during running. Maximal heart rate, however, is lowered by approx. 10 beats/min during swimming compared to running. Most likely active muscle mass is smaller and rate of power production lesser in swimming. Local factors, such as peripheral circulation, capillary density, perfusion pressure and metabolic capacity of active muscles, are important determinants of the power production capacity and emphasize the role of swim specific training movements. Improved swimming technique and efficiency are likely to explain much of the continuous progress in performance. Rational principles based on improved understanding of the biomechanics and physiology of swimming should be guidelines for swimmers and coaches in their efforts to explore the limits of human performance.

  11. H2A-DUBbing the mammalian epigenome: expanding frontiers for histone H2A deubiquitinating enzymes in cell biology and physiology.

    Science.gov (United States)

    Belle, Jad I; Nijnik, Anastasia

    2014-05-01

    Posttranslational modifications of histone H2A through the attachment of ubiquitin or poly-ubiquitin conjugates are common in mammalian genomes and play an important role in the regulation of chromatin structure, gene expression, and DNA repair. Histone H2A deubiquitinases (H2A-DUBs) are a group of structurally diverse enzymes that catalyze the removal ubiquitin from histone H2A. In this review we provide a concise summary of the mechanisms that mediate histone H2A ubiquitination in mammalian cells, and review our current knowledge of mammalian H2A-DUBs, their biochemical activities, and recent developments in our understanding of their functions in mammalian physiology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Poly-lactic acid nanoparticles (PLA-NP) promote physiological modifications in lung epithelial cells and are internalized by clathrin-coated pits and lipid rafts.

    Science.gov (United States)

    da Luz, Camila Macedo; Boyles, Matthew Samuel Powys; Falagan-Lotsch, Priscila; Pereira, Mariana Rodrigues; Tutumi, Henrique Rudolf; de Oliveira Santos, Eidy; Martins, Nathalia Balthazar; Himly, Martin; Sommer, Aniela; Foissner, Ilse; Duschl, Albert; Granjeiro, José Mauro; Leite, Paulo Emílio Corrêa

    2017-01-31

    Poly-lactic acid nanoparticles (PLA-NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA-NP being considered biocompatible, data concerning alterations in cellular physiology are scarce. We conducted an extensive evaluation of PLA-NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells' proteome. We used non- and green-fluorescent PLA-NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA-NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin-coated pits. Cell viability and proliferation were not altered in response to PLA-NP. Multiplex analysis of secreted mediators revealed a low-level reduction of IL-12p70 and vascular epidermal growth factor (VEGF) in response to PLA-NP, while all other mediators assessed were unaffected. However, changes to the cells' proteome were observed in response to PLA-NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA-NP, PLA-NP enhanced susceptibility to STS-induced cell death. Finally, PLA-NP were rapidly internalized in association with clathrin-coated pits, and, to a lesser extent, with lipid rafts. These data demonstrate that PLA-NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro-inflammatory mediators. However, PLA-NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover

  13. A Connection between Transport Phenomena and Thermodynamics

    Science.gov (United States)

    Swaney, Ross; Bird, R. Byron

    2017-01-01

    Although students take courses in transport phenomena and thermodynamics, they probably do not ask whether these two subjects are related. Here we give an answer to that question. Specifically we give relationships between the equations of change for total energy, internal energy, and entropy of transport phenomena and key equations of equilibrium…

  14. Nonlinear dynamical phenomena in liquid crystals

    International Nuclear Information System (INIS)

    Wang, X.Y.; Sun, Z.M.

    1988-09-01

    Because of the existence of the orientational order and anisotropy in liquid crystals, strong nonlinear phenomena and singular behaviors, such as solitary wave, transient periodic structure, chaos, fractal and viscous fingering, can be excited by a very small disturbance. These phenomena and behaviors are in connection with physics, biology and mathematics. 12 refs, 6 figs

  15. Electrical breakdown phenomena of dielectric elastomers

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Yu, Liyun; Skov, Anne Ladegaard

    2017-01-01

    years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we investigate the electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers. Two types...

  16. Physics and (patho)physiology in confined flows: from colloidal patterns to cytoplasmic rheology and sickle cell anemia

    Science.gov (United States)

    Mahadevan, L.

    2015-03-01

    I will discuss a few problems that involve the interaction of fluids and solids in confined spaces. (i) Jamming in pressure-driven suspension flows that show a transition from Stokes flows to Darcy flows as the solids start to lock, as in evaporative patterning in colloids (e.g. coffee stain formation) .(ii) Jamming and clogging of red blood cells, as in sickle-cell pathophysiology, with implications for other diseases that involve jamming. (iii) The mechanical response of crowded networks of filaments bathed in a fluid, as in the cytoskeleton, that can be described by poroelasticity theory. In each case, I will show how simple theories of multiphase flow and deformation can be used to explain a range of experimental observations, while failing to account for others, along with some thoughts on how to improve them.

  17. Physiological effects of manipulating the level of insulin-degrading enzyme in insulin-producing cells of Drosophila

    OpenAIRE

    Hyun, Joogyung; Hashimoto, Carl

    2011-01-01

    Insulin-degrading enzyme (IDE) degrades insulin and other peptides, including the Aβ peptide of Alzheimer's disease. However, the mechanism by which IDE acts on its substrates in vivo is unclear, and its role in pathogenesis of type 2 diabetes and Alzheimer's disease is controversial. Here, we show that in Drosophila knocking down IDE in insulin-producing cells (IPCs) of the brain results in increased body weight and fecundity, decreased circulating sugar levels and reduced lifespan. Moreover...

  18. Physiological and proteomic changes suggest an important role of cell walls in the high tolerance to metals of Elodea nuttallii.

    Science.gov (United States)

    Larras, Floriane; Regier, Nicole; Planchon, Sébastien; Poté, John; Renaut, Jenny; Cosio, Claudia

    2013-12-15

    Macrophytes bioaccumulate metals, the suggestion being made that they be considered for phytoremediation. However, a thorough understanding of the mechanisms of metal tolerance in these plants is necessary to allow full optimization of this approach. The present study was undertaken to gain insight into Hg and Cd accumulation and their effects in a representative macrophyte, Elodea nuttallii. Exposure to methyl-Hg (23 ng dm(-3)) had no significant effect while inorganic Hg (70 ng dm(-3)) and Cd (281 μg dm(-3)) affected root growth but did not affect shoots growth, photosynthesis, or antioxidant enzymes. Phytochelatins were confirmed as having a role in Cd tolerance in this plant while Hg tolerance seems to rely on different mechanisms. Histology and subcellular distribution revealed a localized increase in lignification, and an increased proportion of metal accumulation in cell wall over time. Proteomics further suggested that E. nuttallii was able to efficiently adapt its energy sources and the structure of its cells during Hg and Cd exposure. Storage in cell walls to protect cellular machinery is certainly predominant at environmental concentrations of metals in this plant resulting in a high tolerance highlighted by the absence of toxicity symptoms in shoots despite the significant accumulation of metals. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Intracellular amyloid formation in muscle cells of Aβ-transgenic Caenorhabditis elegans: determinants and physiological role in copper detoxification

    Directory of Open Access Journals (Sweden)

    Bush Ashley I

    2009-01-01

    Full Text Available Abstract Background The amyloid β-peptide is a ubiquitous peptide, which is prone to aggregate forming soluble toxic oligomers and insoluble less-toxic aggregates. The intrinsic and external/environmental factors that determine Aβ aggregation in vivo are poorly understood, as well as the cellular meaning of this process itself. Genetic data as well as cell biological and biochemical evidence strongly support the hypothesis that Aβ is a major player in the onset and development of Alzheimer's disease. In addition, it is also known that Aβ is involved in Inclusion Body Myositis, a common myopathy of the elderly in which the peptide accumulates intracellularly. Results In the present work, we found that intracellular Aβ aggregation in muscle cells of Caenorhabditis elegans overexpressing Aβ peptide is affected by two single amino acid substitutions, E22G (Arctic and V18A (NIC. Both variations show decrease intracellular amyloidogenesis compared to wild type Aβ. We show that intracellular amyloid aggregation of wild type Aβ is accelerated by Cu2+ and diminished by copper chelators. Moreover, we demonstrate through toxicity and behavioral assays that Aβ-transgenic worms display a higher tolerance to Cu2+ toxic effects and that this resistance may be linked to the formation of amyloid aggregates. Conclusion Our data show that intracellular Aβ amyloid aggregates may trap excess of free Cu2+ buffering its cytotoxic effects and that accelerated intracellular Aβ aggregation may be part of a cell protective mechanism.

  20. Advances in transport phenomena 2011

    CERN Document Server

    2014-01-01

    This new volume of the annual review “Advances in Transport Phenomena” series contains three in-depth review articles on the microfluidic fabrication of vesicles, the dielectrophoresis field-flow fractionation for continuous-flow separation of particles and cells in microfluidic devices, and the thermodynamic analysis and optimization of heat exchangers, respectively.

  1. PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena

    Science.gov (United States)

    Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo

    2010-10-01

    Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 (http://needs-conferences.net/2009/). The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed

  2. Molecular and physiological manifestations and measurement of aging in humans.

    Science.gov (United States)

    Khan, Sadiya S; Singer, Benjamin D; Vaughan, Douglas E

    2017-08-01

    Biological aging is associated with a reduction in the reparative and regenerative potential in tissues and organs. This reduction manifests as a decreased physiological reserve in response to stress (termed homeostenosis) and a time-dependent failure of complex molecular mechanisms that cumulatively create disorder. Aging inevitably occurs with time in all organisms and emerges on a molecular, cellular, organ, and organismal level with genetic, epigenetic, and environmental modulators. Individuals with the same chronological age exhibit differential trajectories of age-related decline, and it follows that we should assess biological age distinctly from chronological age. In this review, we outline mechanisms of aging with attention to well-described molecular and cellular hallmarks and discuss physiological changes of aging at the organ-system level. We suggest methods to measure aging with attention to both molecular biology (e.g., telomere length and epigenetic marks) and physiological function (e.g., lung function and echocardiographic measurements). Finally, we propose a framework to integrate these molecular and physiological data into a composite score that measures biological aging in humans. Understanding the molecular and physiological phenomena that drive the complex and multifactorial processes underlying the variable pace of biological aging in humans will inform how researchers assess and investigate health and disease over the life course. This composite biological age score could be of use to researchers seeking to characterize normal, accelerated, and exceptionally successful aging as well as to assess the effect of interventions aimed at modulating human aging. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  3. Avian reproductive physiology

    Science.gov (United States)

    Gee, G.F.; Gibbons, Edward F.; Durrant, Barbara S.; Demarest, Jack

    1995-01-01

    Knowledge of the many physiological factors associated with egg production , fertility, incubation, and brooding in nondomestic birds is limited. Science knows even less about reproduction in most of the 238 endangered or threatened birds. This discussion uses studies of nondomestic and, when necessary, domestic birds to describe physiological control of reproduction. Studies of the few nondomestic avian species show large variation in physiological control of reproduction. Aviculturists, in order to successfully propagate an endangered bird, must understand the bird's reproductive peculiarities. First, investigators can do studies with carefully chosen surrogate species, but eventually they need to confirm the results in the target endangered bird. Studies of reproduction in nondomestic birds increased in the last decade. Still, scientists need to do more comparative studies to understand the mechanisms that control reproduction in birds. New technologies are making it possible to study reproductive physiology of nondomestic species in less limiting ways. These technologies include telemetry to collect information without inducing stress on captives (Howey et al., 1987; Klugman, 1987), new tests for most of the humoral factors associated with reproduction, and the skill to collect small samples and manipulate birds without disrupting the physiological mechanisms (Bercovitz et al., 1985). Managers are using knowledge from these studies to improve propagation in zoological parks, private and public propagation facilities, and research institutions. Researchers need to study the control of ovulation, egg formation, and oviposition in the species of nondomestic birds that lay very few eggs in a season, hold eggs in the oviduct for longer intervals, or differ in other ways from the more thoroughly studied domestic birds. Other techniques that would enhance propagation for nondomestlc birds include tissue culture of cloned embryonic cells, cryopreservation of embryos

  4. Efferent feedback can explain many hearing phenomena

    Science.gov (United States)

    Holmes, W. Harvey; Flax, Matthew R.

    2015-12-01

    The mixed mode cochlear amplifier (MMCA) model was presented at the last Mechanics of Hearing workshop [4]. The MMCA consists principally of a nonlinear feedback loop formed when an efferent-controlled outer hair cell (OHC) is combined with the cochlear mechanics and the rest of the relevant neurobiology. Essential elements of this model are efferent control of the OHC motility and a delay in the feedback to the OHC. The input to the MMCA is the passive travelling wave. In the MMCA amplification is localized where both the neural and tuned mechanical systems meet in the Organ of Corti (OoC). The simplest model based on this idea is a nonlinear delay line resonator (DLR), which is mathematically described by a nonlinear delay-differential equation (DDE). This model predicts possible Hopf bifurcations and exhibits its most interesting behaviour when operating near a bifurcation. This contribution presents some simulation results using the DLR model. These show that various observed hearing phenomena can be accounted for by this model, at least qualitatively, including compression effects, two-tone suppression and some forms of otoacoustic emissions (OAEs).

  5. Exercise Effects on Sleep Physiology

    Directory of Open Access Journals (Sweden)

    Sunao eUchida

    2012-04-01

    Full Text Available This mini-review focuses on the effects of exercise on sleep. In its early days, sleep research largely focused on central nervous system (CNS physiology using standardized tabulations of several sleep-specific landmark electroencephalogram (EEG waveforms. Though coarse, this method has enabled the observation and inspection of numerous uninterrupted sleep phenomena. Thus, research on the effects of exercise on sleep began, in the 1960’s, with a focus primarily on sleep EEG (CNS sleep changes. Those early studies found only small effects of exercise on sleep. More recent sleep research has explored not only CNS functioning, but somatic physiology as well. As physical exercise mostly affects somatic functions, endocrine and autonomic nervous system (ANS changes that occur during sleep should be affected by daytime exercise. Since endocrinological, metabolic and autonomic changes can be measured during sleep, it should be possible to assess exercise effects on somatic physiology in addition to CNS sleep quality, building from standard polysomnographic (PSG techniques. Incorporating measures of somatic physiology in the quantitative assessment of sleep could further our understanding of sleep's function as an auto-regulatory, global phenomenon.

  6. Emergence of dynamical order synchronization phenomena in complex systems

    CERN Document Server

    Manrubia, Susanna C; Zanette, Damián H

    2004-01-01

    Synchronization processes bring about dynamical order and lead tospontaneous development of structural organization in complex systemsof various origins, from chemical oscillators and biological cells tohuman societies and the brain. This book provides a review and adetailed theoretical analysis of synchronization phenomena in complexsystems with different architectures, composed of elements withperiodic or chaotic individual dynamics. Special attention is paid tostatistical concepts, such as nonequilibrium phase transitions, orderparameters and dynamical glasses.

  7. In Vivo Whole-cell Recordings Combined with Electron Microscopy Reveal Unexpected Morphological and Physiological Properties in the Lateral Nucleus of the Trapezoid Body in the Auditory Brainstem

    Directory of Open Access Journals (Sweden)

    Tom P Franken

    2016-08-01

    Full Text Available The lateral nucleus of the trapezoid body (LNTB is a prominent nucleus in the superior olivary complex in mammals including humans. Its physiology in vivo is poorly understood due to a paucity of recordings. It is thought to provide a glycinergic projection to the medial superior olive (MSO with an important role in binaural processing and sound localization. We combined in vivo patch clamp recordings with labeling of individual neurons in the Mongolian gerbil. Labeling of the recorded neurons allowed us to relate physiological properties to anatomy at the light and electron microscopic level. We identified a population of quite dorsally located neurons with surprisingly large dendritic trees on which most of the synaptic input impinges. In most neurons, one or more of these dendrites run through and are then medial to the MSO. These neurons were often binaural and could even show sensitivity to interaural time differences (ITDs of stimulus fine structure or envelope. Moreover, a subpopulation showed enhanced phase-locking to tones delivered in the tuning curve tail. We propose that these neurons constitute the gerbil main LNTB (mLNTB, In contrast, a smaller sample of neurons was identified that was located more ventrally and that we designate to be in posteroventral LNTB (pvLNTB. These cells receive large somatic excitatory terminals from globular bushy cells. We also identified previously undescribed synaptic inputs from the lateral superior olive. pvLNTB neurons are usually monaural, display a primary-like-with-notch response to ipsilateral short tones at CF and can phase-lock to low frequency tones. We conclude that mLNTB contains a population of neurons with extended dendritic trees where most of the synaptic input is found, that can show enhanced phase-locking and sensitivity to ITD. pvLNTB cells, presumed to provide glycinergic input to the MSO, get large somatic globular bushy synaptic inputs and are typically monaural with short tone

  8. Nonlinear Photonics and Novel Optical Phenomena

    CERN Document Server

    Morandotti, Roberto

    2012-01-01

    Nonlinear Photonics and Novel Optical Phenomena contains contributed chapters from leading experts in nonlinear optics and photonics, and provides a comprehensive survey of fundamental concepts as well as hot topics in current research on nonlinear optical waves and related novel phenomena. The book covers self-accelerating airy beams, integrated photonics based on high index doped-silica glass, linear and nonlinear spatial beam dynamics in photonic lattices and waveguide arrays, polariton solitons and localized structures in semiconductor microcavities, terahertz waves, and other novel phenomena in different nanophotonic and optical systems.

  9. Computational transport phenomena for engineering analyses

    CERN Document Server

    Farmer, Richard C; Cheng, Gary C; Chen, Yen-Sen

    2009-01-01

    Computational Transport PhenomenaOverviewTransport PhenomenaAnalyzing Transport PhenomenaA Computational Tool: The CTP CodeVerification, Validation, and GeneralizationSummaryNomenclatureReferencesThe Equations of ChangeIntroductionDerivation of The Continuity EquationDerivation of The Species Continuity EquationDerivation of The Equation Of MotionDerivation of The General Energy EquationNon-Newtonian FluidsGeneral Property BalanceAnalytical and Approximate Solutions for the Equations of ChangeSummaryNomenclatureReferencesPhysical PropertiesOverviewReal-Fluid ThermodynamicsChemical Equilibrium

  10. Transient phenomena in electrical power systems

    CERN Document Server

    Venikov, V A; Higinbotham, W

    1964-01-01

    Electronics and Instrumentation, Volume 24: Transient Phenomena in Electrical Power Systems presents the methods for calculating the stability and the transient behavior of systems with forced excitation control. This book provides information pertinent to the analysis of transient phenomena in electro-mechanical systems.Organized into five chapters, this volume begins with an overview of the principal requirements in an excitation system. This text then explains the electromagnetic and electro-mechanical phenomena, taking into account the mutual action between the components of the system. Ot

  11. Sixteenth International Conference on Ultrafast Phenomena

    CERN Document Server

    Corkum, Paul; Nelson, Keith A; Riedle, Eberhard; Schoenlein, Robert W; Ultrafast Phenomena XVI

    2009-01-01

    Ultrafast Phenomena XVI presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh speed communications. This book summarizes the results presented at the 16th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.

  12. The Disastrous Effects of Salt Dust Deposition on Cotton Leaf Photosynthesis and the Cell Physiological Properties in the Ebinur Basin in Northwest China

    Science.gov (United States)

    Abuduwaili, Jilili; Zhaoyong, Zhang; Feng qing, Jiang; Dong wei, Liu

    2015-01-01

    Salt dust in rump lake areas in arid regions has long been considered an extreme stressor for both native plants and crops. In recent years, research on the harmful effects of salt dust on native plants has been published by many scholars, but the effect on crops has been little studied. In this work, in order to determine the impact of salt dust storms on cotton, we simulated salt dust exposure of cotton leaves in Ebinur Basin in Northwest China, and measured the particle sizes and salt ions in the dust, and the photosynthesis, the structure and the cell physiological properties of the cotton leaves. (1) Analysis found that the salt ions and particle sizes in the salt dust used in the experiments were consistent with the natural salt dust and modeled the salt dust deposition on cotton leaves in this region. (2) The main salt cations on the surface and inside the cotton leaves were Na+, Ca2+, Cl- and SO42-, while the amounts of CO3- and HCO3- were low. From the analysis, we can order the quantity of the salt cations and anions ions present on the surface and inside the cotton leaves as Na+>Ca2+>Mg2+>K+ and Cl->SO42->HCO3->CO3-, respectively. Furthermore, the five salt dust treatment groups in terms of the total salt ions on both the surface and inside the cotton leaves were A(500g.m-2)>B(400g.m-2)>C(300g.m-2)>D(200g.m-2)>E(100g.m-2)>F(0g.m-2). (3)The salt dust that landed on the surface of the cotton leaves can significantly influence the photosynthetic traits of Pn, PE, Ci, Ti, Gs, Tr, WUE, Ls, φ, Amax, k and Rady of the cotton leaves. (4)Salt dust can significantly damage the physiological functions of the cotton leaves, resulting in a decrease in leaf chlorophyll and carotenoid content, and increasing cytoplasmic membrane permeability and malondialdehyde (MDA) content by increasing the soluble sugar and proline to adjust for the loss of the cell cytosol. This increases the activity of antioxidant enzymes to eliminate harmful materials, such as the intracellular

  13. [Human physiology: kidney].

    Science.gov (United States)

    Natochin, Iu V

    2010-01-01

    The content of human physiology as an independent part of current physiology is discussed. Substantiated is the point that subjects of human physiology are not only special sections of physiology where functions are inherent only in human (physiology of intellectual activity, speech, labor, sport), but also in peculiarities of functions, specificity of regulation of each of physiological systems. By the example of physiology of kidney and water-salt balance there are shown borders of norm, peculiarities of regulation in human, new chapters of renal physiology which have appeared in connection with achievements of molecular physiology.

  14. Tif1γ regulates the TGF-β1 receptor and promotes physiological aging of hematopoietic stem cells.

    Science.gov (United States)

    Quéré, Ronan; Saint-Paul, Laetitia; Carmignac, Virginie; Martin, Romain Z; Chrétien, Marie-Lorraine; Largeot, Anne; Hammann, Arlette; Pais de Barros, Jean-Paul; Bastie, Jean-Noël; Delva, Laurent

    2014-07-22

    The hematopoietic system declines with age. Myeloid-biased differentiation and increased incidence of myeloid malignancies feature aging of hematopoietic stem cells (HSCs), but the mechanisms involved remain uncertain. Here, we report that 4-mo-old mice deleted for transcription intermediary factor 1γ (Tif1γ) in HSCs developed an accelerated aging phenotype. To reinforce this result, we also show that Tif1γ is down-regulated in HSCs during aging in 20-mo-old wild-type mice. We established that Tif1γ controls TGF-β1 receptor (Tgfbr1) turnover. Compared with young HSCs, Tif1γ(-/-) and old HSCs are more sensitive to TGF-β signaling. Importantly, we identified two populations of HSCs specifically discriminated by Tgfbr1 expression level and provided evidence of the capture of myeloid-biased (Tgfbr1(hi)) and myeloid-lymphoid-balanced (Tgfbr1(lo)) HSCs. In conclusion, our data provide a new paradigm for Tif1γ in regulating the balance between lymphoid- and myeloid-derived HSCs through TGF-β signaling, leading to HSC aging.

  15. Exchange transfusion with entirely synthetic red-cell substitute albumin-heme into rats: physiological responses and blood biochemical tests.

    Science.gov (United States)

    Huang, Yubin; Komatsu, Teruyuki; Yamamoto, Hisashi; Horinouchi, Hirohisa; Kobayashi, Koichi; Tsuchida, Eishun

    2004-10-01

    Recombinant human serum albumin (rHSA) incorporating 2-[8-[N-(2-methylimidazolyl)]octanoyloxymethyl]-5,10,15,20-[tetrakis[alpha,alpha,alpha,alpha-o-(1-methylcyclohexanoyl)amino]phenyl]porphinatoiron(II) [albumin-heme (rHSA-heme)] is an artificial hemoprotein which has the capability to transport O(2) in vitro and in vivo. A 20% exchange transfusion with rHSA-heme into anesthetized rats has been performed to evaluate its clinical safety by monitoring the circulation parameters and blood parameters for 6 h after the infusion. Time course changes in all parameters essentially showed the same features as those of the control group (without infusion) and rHSA group (with administration of the same amount of rHSA). Blood biochemical tests of the withdrawn plasma at 6 h after the exchange transfusion have also been carried out. No significant difference was found between the rHSA-heme and rHSA groups, suggesting the initial clinical safety of this entirely synthetic O(2)-carrier as a red-cell substitute.

  16. Role of Gal and GalNAc containing glycans in various physiological ...

    African Journals Online (AJOL)

    Muhammad Ramzan Manwar Hussain

    2011-09-28

    Sep 28, 2011 ... GalNAc, which has its specific physiological role in lectin binding or recognition process [23,46–53]. Physiological efficacy of these modifications and their association in various cellular phenomena are given below. 5.1. Physiological significance of sulfated Gal and GalNAc. Sulfated glycoconjugates occur ...

  17. High Temperature Phenomena in Shock Waves

    CERN Document Server

    2012-01-01

    The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows an...

  18. Conditioning and breakdown phenomena in accelerator tubes

    International Nuclear Information System (INIS)

    Skorka, S.J.

    1979-01-01

    Important breakdown mechanisms in accelerator tubes are reviewed, and discharge phenomena in NEC tubes are deduced from the surface appearance of the electrodes and insulators of a used tube. Microphotos of these surfaces are shown

  19. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Black holes; numerical relativity; nonlinear sigma. Abstract. Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. ... Theoretical and Computational Studies Group, Southampton College, Long Island University, Southampton, NY 11968, USA ...

  20. Periglacial phenomena affecting nuclear waste disposal

    Directory of Open Access Journals (Sweden)

    Niini, H.

    1997-12-01

    Full Text Available Slow future changes in astronomic phenomena seem to make it likely that Finland nll suffer several cold periods during the next 100,000 years. The paper analyses the characteristics of the periglacial factors that are most likely to influence the long-term safety of high-level radioactive waste disposed of in bedrock. These factors and their influences have been divided into two categories, natural and human. It is concluded that the basically natural phenomena are theoretically better understood than the complicated phenomena caused by man. It is therefore important in future research into periglacial phenomena, as well as of the disposal problem, to emphasize not only the proper applications of the results of natural sciences, but especially the effects and control of mankind's own present and future activities.

  1. Evidence on Dropout Phenomena at Universities

    DEFF Research Database (Denmark)

    Larsen, Malene Rode; Sommersel, Hanna Bjørnøy; Larsen, Michael Søgaard

    This publication is an excerpt from the full technical report ‘Dropout Phenomena at Universities: What is Dropout? Why does Dropout Occur? What Can be Done by the Universities to Prevent or Reduce it? A systematic review’, which was completed in April 2013. The purpose of this excerpt is to prese...... the knowledge we have on dropout phenomena at European universities in a short, precise and comprehensible form to allow readers to orient themselves on the subject in a more readable manner....

  2. Transport phenomena an introduction to advanced topics

    CERN Document Server

    Glasgow, Larry A

    2010-01-01

    Enables readers to apply transport phenomena principles to solve advanced problems in all areas of engineering and science This book helps readers elevate their understanding of, and their ability to apply, transport phenomena by introducing a broad range of advanced topics as well as analytical and numerical solution techniques. Readers gain the ability to solve complex problems generally not addressed in undergraduate-level courses, including nonlinear, multidimensional transport, and transient molecular and convective transport scenarios. Avoiding rote memorization, the author em

  3. Second DOE natural phenomena hazards mitigation conference

    International Nuclear Information System (INIS)

    1989-01-01

    This conference has been organized into ten presentation sessions which include an overview of the DOE Natural Phenomena Guidelines, Seismic Analysis, Seismic Design, Modifying Existing Facilities, DOE Orders, Codes, and Standards (2 sessions), Seismic Hazard (2 sessions), and Probabilistic Risk Assessment (2 sessions). Two poster sessions were also included in the program to provide a different forum for communication of ideas. Over the past fourteen years, Lawrence Livermore National Laboratory, Nuclear Systems Safety Program, has been working with the US Department of Energy, Office of Safety Appraisals and their predecessors in the area of natural phenomena hazards. During this time we have developed seismic, extreme wind/tornado, and flood hazard models for DOE sites in the United States. Guidelines for designing and evaluating DOE facilities for natural phenomena have been developed and are in interim use throughout the DOE community. A series of state-of-the practice manuals have also been developed to aid the designers. All of this material is listed in the Natural Phenomena Hazards Bibliography included in these proceedings. This conference provides a mechanism to disseminate current information on natural phenomena hazards and their mitigation. It provides an opportunity to bring together members of the DOE community to discuss current projects, to share information, and to hear practicing members of the structural engineering community discuss their experiences from past natural phenomena, future trends, and any changes to building codes. Each paper or poster presented is included in these proceedings. We have also included material related to the luncheon and dinner talks

  4. Impact of ADMA (asymmetric dimethylarginine) on physiology with respect to diabetes mellitus and respiratory system BEAS-2B cells (human bronchial epithelial cells).

    Science.gov (United States)

    Galal, Omneya; Podlogar, Julia; Verspohl, Eugen J

    2013-02-01

    Asymmetric dimethylarginine (ADMA) is a non-selective nitric oxide (NO) synthase inhibitor associated with cardiovascular and metabolic disorders. This study aimed to investigate ADMA with respect to both diabetes and respiratory disease. Glucose was determined by hexokinase method, insulin by a radioimmunoassay. Griess test was used for NO assay and cytokinines were assayed by ELISA. Ciliary beat frequency was determined by high speed video using a microscope. ADMA induced an increase in blood glucose and plasma insulin levels in rats; the ratio of these effects indicates the induction of a diabetic situation (insulin resistance). L-arginine increased blood glucose and initially slightly decreased plasma insulin. A pretreatment with ADMA abolished these effects. ADMA shows similar effects in vitro (insulin-secreting cell line, INS-1 cells). L-arginine increased production of NO, which was reversed by ADMA (INS-1 cells). ADMA also reduced NO production positively modulated by various substances, namely metformin, ciglitazone, losartan and nateglinide, but nevertheless inhibited insulin release induced by these compounds. ADMA stimulated the production of cytokines such as interleukin (IL-6) and macrophage inflammatory protein-2 (MIP-2) (rat IL-8 analogue) from INS-1 cells. 5-Aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR), a direct adenosine monophosphate protein kinase (AMPK) activator and anti-inflammatory agent, induced NO production and reduced cytokine release. In contrast to diabetes parameters, ADMA had no effect of on the respiratory system (cytokine secretion from BEAS-2B cells (IL-8, regulated on activation, normal T cell expressed and secreted, and tumour necrosis factor-α), ciliary beat frequency and smooth muscle contraction of rat trachea). ADMA has a pathophysiological impact leading to a diabetic situation but has no impact on the respiratory system. © 2012 The Authors. JPP © 2012. Royal Pharmaceutical Society.

  5. Theoretical and experimental notes on noise phenomena of KUR

    International Nuclear Information System (INIS)

    Kishida, Kuniharu

    1980-01-01

    The classification of global or local noise is important in reactor noise analysis. The term of ''global'' or ''local'' corresponds to that of ''system size'' or ''cell size'' in statistical physics. On the other hand, point model or phase space description is used in time series analysis. If a time series model describing spatial behavior is established, it will serve to reactor diagnosis. The noise phenomena of KUR are discussed from these points of view. In other words, from experimental results, the point reactor picture is reasonable to neutronic aspect but quantitative problem remains in coolant temperature fluctuations. By taking into account a diffusion type model, the spatial dependence is discussed for the problem remaining in coolant temperature fluctuations. It is pointed out that the time-space picture is a crucial idea of reactor noise phenomena. (author)

  6. Phenomena of synchronized response in biosystems and the possible mechanism.

    Science.gov (United States)

    Xu, Jingjing; Yang, Fan; Han, Danhong; Xu, Shengyong

    2018-02-05

    Phenomena of synchronized response is common among organs, tissues and cells in biosystems. We have analyzed and discussed three examples of synchronization in biosystems, including the direction-changing movement of paramecia, the prey behavior of flytraps, and the simultaneous discharge of electric eels. These phenomena and discussions support an electrical communication mechanism that in biosystems, the electrical signals are mainly soliton-like electromagnetic pulses, which are generated by the transient transmembrane ionic current through the ion channels and propagate along the dielectric membrane-based softmaterial waveguide network to complete synchronized responses. This transmission model implies that a uniform electrical communication mechanism might have been naturally developed in biosystem. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Geochemical modelling: what phenomena are missing

    International Nuclear Information System (INIS)

    Jacquier, P.

    1989-12-01

    In the framework of safety assessment of radioactive waste disposal, retention phenomena are usually taken into account by the Kd concept. It is well recognized that this concept is not enough for safety assessment models, because of the several and strong assumptions which are involved in this kind of representation. One way to have a better representation of the retention phenomena, is to substitute for this Kd concept an explicit description of geochemical phenomena and then couple transport codes with geochemical codes in a fully or a two-step procedure. We use currently such codes, but the scope of this paper is to display the limits today of the geochemical modelling in connection with sites analysis for deep disposal. In this paper, we intend to give an overview of phenomena which are missing in the geochemical models, or which are not completely introduced in the models. We can distinguish, on one hand phenomena for which modelling concepts exist such as adsorption/desorption and, on the other hand, phenomena for which modelling concepts do not exist for the moment such as colloids, and complexation by polyelectrolyte solutions (organics). Moreover we have to take care of very low concentrations of radionuclides, which can be expected from the leaching processes in the repository. Under those conditions, some reactions may not occur. After a critical review of the involved phenomena, we intend to stress the main directions of the wishful evolution of the geochemical modelling. This evolution should improve substantially the quality of the above-mentioned site assessments

  8. High efficiency cell-recycle continuous sodium gluconate production by Aspergillus niger using on-line physiological parameters association analysis to regulate feed rate rationally.

    Science.gov (United States)

    Lu, Fei; Li, Chao; Wang, Zejian; Zhao, Wei; Chu, Ju; Zhuang, Yingping; Zhang, Siliang

    2016-11-01

    In this paper, a system of cell-recycle continuous fermentation for sodium gluconate (SG) production by Aspergillus niger (A. niger) was established. Based on initial continuous fermentation result (100.0h) with constant feed rate, an automatic feedback strategy to regulate feed rate using on-line physiological parameters (OUR and DO) was proposed and applied successfully for the first time in the improved continuous fermentation (240.5h). Due to less auxiliary time, highest SG production rate (31.05±0.29gL(-1)h(-1)) and highest yield (0.984±0.067molmol(-1)), overall SG production capacity (975.8±5.8gh(-1)) in 50-L fermentor of improved continuous fermentation increased more than 300.0% compared to that of batch fermentation. Improvement of mass transfer and dispersed mycelia morphology were the two major reasons responsible for the high SG production rate. This system had been successfully applied to industrial fermentation and SG production was greatly improved. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. An azine based sensor for selective detection of Cu2 + ions and its copper complex for sensing of phosphate ions in physiological conditions and in living cells

    Science.gov (United States)

    Tiwari, Karishma; Kumar, Sumit; Kumar, Vipan; Kaur, Jeevanjot; Arora, Saroj; Mahajan, Rakesh Kumar

    2018-02-01

    A simple and cost effective unsymmetrical azine based Schiff base, 5-diethylamino-2-[(2-hydroxy-benzylidene)hydrazonomethyl]-phenol (1) was synthesized which selectively detect Cu2 + ions in the presence of other competitive ions through ;naked eye; in physiological conditions (EtOH-buffer (1:1, v/v, HEPES 10 mM, pH = 7.4)). The presence of Cu2 + induce color change from light yellow green to yellow with the appearance of a new band at 450 nm in UV-Vis spectra of Schiff base 1. The fluorescence of Schiff base 1 (10 μM) was quenched completely in the presence of 2.7 equiv. of Cu2 + ions. Sub-micromolar limit of detection (LOD = 3.4 × 10- 7 M), efficient Stern-Volmer quenching constant (KSV = 1.8 × 105 L mol- 1) and strong binding constant (log Kb = 5.92) has been determined with the help of fluorescence titration profile. Further, 1 - Cu2 + complex was employed for the detection of phosphate ions (PO43 -, HPO42 - and H2PO4-) at micromolar concentrations in EtOH-buffer of pH 7.4 based on fluorescence recovery due to the binding of Cu2 + with phosphate ions. Solubility at low concentration in aqueous medium, longer excitation (406 nm) and emission wavelength (537 nm), and biocompatibility of Schiff base 1 formulates its use in live cell imaging.

  10. An update: improvements in imaging perfluorocarbon-mounted plant leaves with implications for studies of plant pathology, physiology, development and cell biology.

    Science.gov (United States)

    Littlejohn, George R; Mansfield, Jessica C; Christmas, Jacqueline T; Witterick, Eleanor; Fricker, Mark D; Grant, Murray R; Smirnoff, Nicholas; Everson, Richard M; Moger, Julian; Love, John

    2014-01-01

    Plant leaves are optically complex, which makes them difficult to image by light microscopy. Careful sample preparation is therefore required to enable researchers to maximize the information gained from advances in fluorescent protein labeling, cell dyes and innovations in microscope technologies and techniques. We have previously shown that mounting leaves in the non-toxic, non-fluorescent perfluorocarbon (PFC), perfluorodecalin (PFD) enhances the optical properties of the leaf with minimal impact on physiology. Here, we assess the use of the PFCs, PFD, and perfluoroperhydrophenanthrene (PP11) for in vivo plant leaf imaging using four advanced modes of microscopy: laser scanning confocal microscopy (LSCM), two-photon fluorescence microscopy, second harmonic generation microscopy, and stimulated Raman scattering (SRS) microscopy. For every mode of imaging tested, we observed an improved signal when leaves were mounted in PFD or in PP11, compared to mounting the samples in water. Using an image analysis technique based on autocorrelation to quantitatively assess LSCM image deterioration with depth, we show that PP11 outperformed PFD as a mounting medium by enabling the acquisition of clearer images deeper into the tissue. In addition, we show that SRS microscopy can be used to image PFCs directly in the mesophyll and thereby easily delimit the "negative space" within a leaf, which may have important implications for studies of leaf development. Direct comparison of on and off resonance SRS micrographs show that PFCs do not to form intracellular aggregates in live plants. We conclude that the application of PFCs as mounting media substantially increases advanced microscopy image quality of living mesophyll and leaf vascular bundle cells.

  11. An update: improvements in imaging perfluorocarbon-mounted plant leaves with implications for studies of plant pathology, physiology, development and cell biology.

    Directory of Open Access Journals (Sweden)

    George R Littlejohn

    2014-04-01

    Full Text Available Plant leaves are optically complex, which makes them difficult to image by light microscopy. Careful sample preparation is therefore required to enable researchers to maximise the information gained from advances in fluorescent protein labelling, cell dyes and innovations in microscope technologies and techniques. We have previously shown that mounting leaves in the non-toxic, non-fluorescent perfluorocarbon (PFC, perfluorodecalin (PFD enhances the optical properties of the leaf with minimal impact on physiology. Here, we assess the use of the perfluorocarbons PFD, and perfluoroperhydrophenanthrene (PP11 for in vivo plant leaf imaging using 4 advanced modes of microscopy: laser scanning confocal microscopy (LSCM, Two-photon fluorescence (TPF microscopy, second harmonic generation (SHG microscopy and stimulated Raman scattering (SRS microscopy. For every mode of imaging tested, we observed an improved signal when leaves were mounted in PFD or in PP11, compared to mounting the samples in water. Using an image analysis technique based on autocorrelation to quantitatively assess LSCM image deterioration with depth, we show that PP11 outperformed PFD as a mounting medium by enabling the acquisition of clearer images deeper into the tissue. In addition, we show that SRS microscopy can be used to image perfluorocarbons directly in the mesophyll and thereby easily delimit the negative space within a leaf, which may have important implications for studies of leaf development. Direct comparison of on and off resonance SRS micrographs show that PFCs do not to form intracellular aggregates in live plants. We conclude that the application of PFCs as mounting media substantially increases advanced microscopy image quality of living mesophyll and leaf vascular bundle cells.

  12. COMPUTER GRAPHICS IN SIMULATION OF CARDIOVASCULAR TRANSPORT PHENOMENA*

    Science.gov (United States)

    Sidell, P. M.; Anderson, D. U.; Knopp, T. J.; Bassingthwaighte, J. B.

    2010-01-01

    Simulation is a necessary tool if we are to understand better the complexities involved in cardiovascular transport. While some of the phenomena modeled can be described analytically, perusal of the equations alone often doesn’t result in full appreciation of the model system. It therefore becomes pertinent to utilize computer graphics in order to enhance simulation of physiologic transport processes. Graphic representation not only facilitates interaction between the investigator and the simulation, it provides a juxtaposition of the model to the real system, as well as a simplification of relationships between various features of the model. Increased mathematical sophistication required in the investigation of cardiovascular transport phenomena often makes traditional graphic representation cumbersome. Therefore several different types of graphics have been utilized, including 2-, 3-, and 4-dimensional displays. The methods and algorithms for these displays have been generalized to make them easy to use over a broad spectrum of applications. In some cases we have generated motion pictures of sequential model solutions which have increased and accelerated model comprehension, as well as been valuable for teaching purposes. PMID:21743760

  13. [Spiritual phenomena occurring in everybody and health].

    Science.gov (United States)

    Krsiak, M

    2008-01-01

    The past several years have seen an explosion of research in the area of spirituality and health. However, confusion and incomprehension of the conception of spirituality (e.g. confounding spirituality with various conventional views on religiousness) hampers better understanding in this area. The present paper proposes definition of spiritual phenomena in man based on natural epistemological and instrumental criteria (whether a certain phenomenon can be objectively known and evoked): spiritual phenomena in man are those, which cannot be objectively known nor evoked, but which act (e.g., love, idea). Spiritual phenomena can be really known only in the self ("in spirit"). Objectively known can be only manifestations of spiritual phenomena. Some attributes of love (e.g. its personal uniqueness) or ideas (e.g., sense of own life) whose satisfaction appears to be important for health are briefly outlined. A review of some frequently cited recent papers investigating the role of spirituality in health and discussion of frequent pitfalls in this area is given. Spirituality is a universal human phenomenon. All human beings, secular or religious, encounter with spiritual phenomena. Although the present conception of spirituality distances from some conventional views on religiousness, it is not atheistic. On the contrary, it accommodates the basic religious concept "God is love". Conceptual clarification is essential for further progress in the study of impact of spirituality on health.

  14. Inertial confinement fusion reactor cavity phenomena

    International Nuclear Information System (INIS)

    Bohachevsky, I.O.; Hafer, J.F.; Devaney, J.J.; Pendergrass, J.H.

    1978-01-01

    Cavity phenomena in Inertial Confinement Fusion (ICF) are created by the interaction of energy released by the fuel pellet microexplosion with the medium inside the reactor cavity. The ambient state of the medium in ICF reactor cavities is restricted primarily by its effects on laser beam propagation and on the fuel pellet trajectory. Therefore, a relatively wide choice of ambient conditions can be exploited to gain first-wall protection and advantages in energy extraction. Depending on the choice of ambient cavity conditions and on fuel pellet design, a variety of physical phenomena may develop and dominate the ICF reactor cavity design. Because of the cavity phenomena, the forms of energy released by the fuel-pellet microexplosion are modified before reaching the first wall, thus giving rise to different cavity design problems. The types of cavity phenomena encountered in the conceptual design of ICF reactors are examined, the approaches available for their modeling and analysis are discussed, and some results are presented. Most phenomena are sufficiently well understood to permit valid engineering assessments of the proposed ICF reactor concepts

  15. Ca2+ influx and tyrosine kinases trigger Bordetella adenylate cyclase toxin (ACT endocytosis. Cell physiology and expression of the CD11b/CD18 integrin major determinants of the entry route.

    Directory of Open Access Journals (Sweden)

    Kepa B Uribe

    Full Text Available Humans infected with Bordetella pertussis, the whooping cough bacterium, show evidences of impaired host defenses. This pathogenic bacterium produces a unique adenylate cyclase toxin (ACT which enters human phagocytes and catalyzes the unregulated formation of cAMP, hampering important bactericidal functions of these immune cells that eventually cause cell death by apoptosis and/or necrosis. Additionally, ACT permeabilizes cells through pore formation in the target cell membrane. Recently, we demonstrated that ACT is internalised into macrophages together with other membrane components, such as the integrin CD11b/CD18 (CR3, its receptor in these immune cells, and GM1. The goal of this study was to determine whether ACT uptake is restricted to receptor-bearing macrophages or on the contrary may also take place into cells devoid of receptor and gain more insights on the signalling involved. Here, we show that ACT is rapidly eliminated from the cell membrane of either CR3-positive as negative cells, though through different entry routes, which depends in part, on the target cell physiology and characteristics. ACT-induced Ca(2+ influx and activation of non-receptor Tyr kinases into the target cell appear to be common master denominators in the different endocytic strategies activated by this toxin. Very importantly, we show that, upon incubation with ACT, target cells are capable of repairing the cell membrane, which suggests the mounting of an anti-toxin cell repair-response, very likely involving the toxin elimination from the cell surface.

  16. Ca2+ Influx and Tyrosine Kinases Trigger Bordetella Adenylate Cyclase Toxin (ACT) Endocytosis. Cell Physiology and Expression of the CD11b/CD18 Integrin Major Determinants of the Entry Route

    Science.gov (United States)

    Etxebarria, Aitor; González-Bullón, David; Gómez-Bilbao, Geraxane; Ostolaza, Helena

    2013-01-01

    Humans infected with Bordetella pertussis, the whooping cough bacterium, show evidences of impaired host defenses. This pathogenic bacterium produces a unique adenylate cyclase toxin (ACT) which enters human phagocytes and catalyzes the unregulated formation of cAMP, hampering important bactericidal functions of these immune cells that eventually cause cell death by apoptosis and/or necrosis. Additionally, ACT permeabilizes cells through pore formation in the target cell membrane. Recently, we demonstrated that ACT is internalised into macrophages together with other membrane components, such as the integrin CD11b/CD18 (CR3), its receptor in these immune cells, and GM1. The goal of this study was to determine whether ACT uptake is restricted to receptor-bearing macrophages or on the contrary may also take place into cells devoid of receptor and gain more insights on the signalling involved. Here, we show that ACT is rapidly eliminated from the cell membrane of either CR3-positive as negative cells, though through different entry routes, which depends in part, on the target cell physiology and characteristics. ACT-induced Ca2+ influx and activation of non-receptor Tyr kinases into the target cell appear to be common master denominators in the different endocytic strategies activated by this toxin. Very importantly, we show that, upon incubation with ACT, target cells are capable of repairing the cell membrane, which suggests the mounting of an anti-toxin cell repair-response, very likely involving the toxin elimination from the cell surface. PMID:24058533

  17. The making of extraordinary psychological phenomena.

    Science.gov (United States)

    Lamont, Peter

    2012-01-01

    This article considers the extraordinary phenomena that have been central to unorthodox areas of psychological knowledge. It shows how even the agreed facts relating to mesmerism, spiritualism, psychical research, and parapsychology have been framed as evidence both for and against the reality of the phenomena. It argues that these disputes can be seen as a means through which beliefs have been formulated and maintained in the face of potentially challenging evidence. It also shows how these disputes appealed to different forms of expertise, and that both sides appealed to belief in various ways as part of the ongoing dispute about both the facts and expertise. Finally, it shows how, when a formal Psychology of paranormal belief emerged in the twentieth century, it took two different forms, each reflecting one side of the ongoing dispute about the reality of the phenomena. © 2012 Wiley Periodicals, Inc.

  18. Neuronal responses to physiological stress

    DEFF Research Database (Denmark)

    Kagias, Konstantinos; Nehammer, Camilla; Pocock, Roger David John

    2012-01-01

    Physiological stress can be defined as any external or internal condition that challenges the homeostasis of a cell or an organism. It can be divided into three different aspects: environmental stress, intrinsic developmental stress, and aging. Throughout life all living organisms are challenged ...

  19. Physiology Applied to Everyday: The Practice of Professional Contextualization of Physiology Concepts as a Way of Facilitating Learning

    Science.gov (United States)

    Borges, Sidnei; Mello-Carpes, Pâmela Billig

    2014-01-01

    The teaching of Physiology is indispensable in many biological and health disciplines. Physiology is one of the major components of the curriculum in a number of life science courses, including the study of life, cells, tissues, and organisms as well as their functions. A bigger challenge for physiology teachers is to make physiological concepts…

  20. Current-driven phenomena in nanoelectronics

    CERN Document Server

    Seideman, Tamar

    2010-01-01

    Consisting of ten chapters written by some of the world's leaders in the field, this book combines experimental, theoretical and numerical studies of current-driven phenomena in the nanoscale. The topics covered range from single-molecule, site-specific nanochemistry induced by a scanning tunneling microscope, through inelastic tunneling spectroscopy and current-induced heating, to current-triggered molecular machines. The various chapters focus on experimental and numerical method development, the description of specific systems, and new ideas and novel phenomena.

  1. Dissipative phenomena in condensed matter some applications

    CERN Document Server

    Dattagupta, Sushanta

    2004-01-01

    From the field of nonequilibrium statistical physics, this graduate- and research-level volume treats the modeling and characterization of dissipative phenomena. A variety of examples from diverse disciplines like condensed matter physics, materials science, metallurgy, chemical physics etc. are discussed. Dattagupta employs the broad framework of stochastic processes and master equation techniques to obtain models for a wide range of experimentally relevant phenomena such as classical and quantum Brownian motion, spin dynamics, kinetics of phase ordering, relaxation in glasses, dissipative tunneling. It provides a pedagogical exposition of current research material and will be useful to experimentalists, computational physicists and theorists.

  2. Arcing phenomena in fusion devices workshop

    Energy Technology Data Exchange (ETDEWEB)

    Clausing, R.E.

    1979-01-01

    The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientists, and both theoreticians and experimentalists engaged in assessing the importance of unipolar arcing in today's tokamaks. Abstracts for papers presented at the workshop are included.

  3. Third DOE natural phenomena hazards mitigation conference

    International Nuclear Information System (INIS)

    1991-01-01

    This conference on Natural Phenomena Hazards Mitigation has been organized into 15 presentation, panel, and poster sessions. The sessions included an overview of activities at DOE Headquarters; natural phenomena hazards tasks underway for DOE; two sessions on codes, standards, orders, criteria, and guidelines; two sessions on seismic hazards; equipment qualification; wind; PRA and margin assessments; modifications, retrofit, and restart; underground structures with a panel discussion; seismic analysis; seismic evaluation and design; and a poster session. Individual projects are processed separately for the data bases

  4. Arcing phenomena in fusion devices workshop

    International Nuclear Information System (INIS)

    Clausing, R.E.

    1979-01-01

    The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientists, and both theoreticians and experimentalists engaged in assessing the importance of unipolar arcing in today's tokamaks. Abstracts for papers presented at the workshop are included

  5. Synchronization Phenomena in Coupled Colpitts Circuits

    Directory of Open Access Journals (Sweden)

    Ch. K. Volos

    2014-11-01

    Full Text Available In this work, the case of coupling (bidirectional and unidirectional between two identical nonlinear chaotic circuits via a linear resistor, is studied. The produced dynamical systems have different structure, in regard to other similar works, due to the choice of coupling nodes. As a circuit, a modification of the most well-known nonlinear circuit that can operate in a wide range of radiofrequencies, the Colpitts oscillator, is chosen. The simulation and the experimental results show a variety of dynamical phenomena, such as periodic, quasi-periodic and chaotic behaviors, as well as anti-phase and complete synchronization phenomena, depending on the value of the coupling coefficient.

  6. 19th International Conference on Ultrafast Phenomena

    CERN Document Server

    Cundiff, Steven; Vivie-Riedle, Regina; Kuwata-Gonokami, Makoto; DiMauro, Louis

    2015-01-01

    This book presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond, and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh-speed communications. This book summarizes the results presented at the 19th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.

  7. Surface phenomena of high energy Li(Ni1/3Co1/3Mn1/3)O2/graphite cells at high temperature and high cutoff voltages

    Science.gov (United States)

    Liu, Ting; Garsuch, Arnd; Chesneau, Frederick; Lucht, Brett L.

    2014-12-01

    Layered Li(Ni1/3Co1/3Mn1/3)O2 (NCM) materials have been investigated at high working potential and elevated temperature to correlate electrochemical performance with changes to the electrode interface. Graphite/NCM cells were cycled to either 4.2 or 4.5 V vs Li/Li+ at room temperature (25 °C) followed by moderately elevated temperature (55 °C). Cells cycled to 4.2 and 4.5 V have similar capacity retention, but the cells cycled to 4.5 V have poorer first cycle efficiency, efficiency upon cycling at 55 °C, and greater increases in cell resistance. Surface analyses indicate thicker surface films on the cathode after cycling to 4.5 V, compared to cycling at a lower voltage of 4.2 V. The thicker surface film on the cathode is the result of electrolyte oxidation to generate poly(ethylene carbonate) and lithium alkyl carbonates. Electrochemical impedance spectroscopy of three-electrode cells reveals that the cathode dominates the cell impedance and the cathode impedance is much greater for cells cycled to 4.5 V than cells cycled to 4.2 V.

  8. Phage Therapy: Eco-Physiological Pharmacology

    Directory of Open Access Journals (Sweden)

    Stephen T. Abedon

    2014-01-01

    Full Text Available Bacterial virus use as antibacterial agents, in the guise of what is commonly known as phage therapy, is an inherently physiological, ecological, and also pharmacological process. Physiologically we can consider metabolic properties of phage infections of bacteria and variation in those properties as a function of preexisting bacterial states. In addition, there are patient responses to pathogenesis, patient responses to phage infections of pathogens, and also patient responses to phage virions alone. Ecologically, we can consider phage propagation, densities, distribution (within bodies, impact on body-associated microbiota (as ecological communities, and modification of the functioning of body “ecosystems” more generally. These ecological and physiological components in many ways represent different perspectives on otherwise equivalent phenomena. Comparable to drugs, one also can view phages during phage therapy in pharmacological terms. The relatively unique status of phages within the context of phage therapy as essentially replicating antimicrobials can therefore result in a confluence of perspectives, many of which can be useful towards gaining a better mechanistic appreciation of phage therapy, as I consider here. Pharmacology more generally may be viewed as a discipline that lies at an interface between organism-associated phenomena, as considered by physiology, and environmental interactions as considered by ecology.

  9. Franz Brentano and the beginning of experimental psychology: implications for the study of psychological phenomena today.

    Science.gov (United States)

    Meyer, Andreas; Hackert, Benedikt; Weger, Ulrich

    2018-03-01

    The manifestation of psychology as an academic discipline more than a 100 years ago was accompanied by a paradigm shift in our understanding of psychological phenomena-with both its light and shadow sides. On the one hand, this development allowed for a rigorous and experimentation-based approach to psychological phenomena; on the other, it led to an alienation from the experiential-or qualia-facets as the topics under inquiry were researched increasingly through third-person (e.g., behavioral or physiological) measures. At the turning point of this development stood an eminent but little known European scholar, Franz Brentano, who called for a synthesis of both third-person and first-person research methods in the study of psychological phenomena. On the occasion of his death, a hundred years ago on March 17, 1917 we wish to illustrate the historical background, introduce the reader to Brentano's approach and work and discuss its relevance for experimental psychology today.

  10. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an

  11. Novel experimentally observed phenomena in soft matter

    Indian Academy of Sciences (India)

    The resulting flow is non-Newtonian and is characterized by features such as shear rate-dependent viscosities and nonzero normal stresses. This article begins with an introduction to some unusual flow properties displayed by soft matter. Experiments that report a spectrum of novel phenomena exhibited by these materials, ...

  12. Fourier Series The Mathematics of Periodic Phenomena

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 10. Fourier Series The Mathematics of Periodic Phenomena. S Thangavelu ... Author Affiliations. S Thangavelu1. Department of Mathematics and Statistics, University of New Mexico, Humanities Building 419, Albuquerque, NM 87131-1141, USA ...

  13. Simple classical approach to spin resonance phenomena

    DEFF Research Database (Denmark)

    Gordon, R A

    1977-01-01

    A simple classical method of describing spin resonance in terms of the average power absorbed by a spin system is discussed. The method has several advantages over more conventional treatments, and a number of important spin resonance phenomena, not normally considered at the introductory level...

  14. DOE natural phenomena hazards mitigation conference: proceedings

    International Nuclear Information System (INIS)

    1985-10-01

    The conference includes sessions which present an overview of DOE programs, available codes, standards and criteria, examples of designs and upgrades from the DOE complex, lessons learned from past natural phenomena, ground motion, seismic evaluation of equipment, and applications of probabilistic risk assessment techniques to DOE facilities. Separate abstracts have been prepared for individual papers

  15. Geophysical phenomena classification by artificial neural networks

    Science.gov (United States)

    Gough, M. P.; Bruckner, J. R.

    1995-01-01

    Space science information systems involve accessing vast data bases. There is a need for an automatic process by which properties of the whole data set can be assimilated and presented to the user. Where data are in the form of spectrograms, phenomena can be detected by pattern recognition techniques. Presented are the first results obtained by applying unsupervised Artificial Neural Networks (ANN's) to the classification of magnetospheric wave spectra. The networks used here were a simple unsupervised Hamming network run on a PC and a more sophisticated CALM network run on a Sparc workstation. The ANN's were compared in their geophysical data recognition performance. CALM networks offer such qualities as fast learning, superiority in generalizing, the ability to continuously adapt to changes in the pattern set, and the possibility to modularize the network to allow the inter-relation between phenomena and data sets. This work is the first step toward an information system interface being developed at Sussex, the Whole Information System Expert (WISE). Phenomena in the data are automatically identified and provided to the user in the form of a data occurrence morphology, the Whole Information System Data Occurrence Morphology (WISDOM), along with relationships to other parameters and phenomena.

  16. Analysis of induction phenomena in thermonuclear experiments

    International Nuclear Information System (INIS)

    Deeds, W.E.; Dodd, C.V.

    1976-01-01

    Many of the problems involving transients induced by changing currents in the large coils of thermonuclear machines are identical to those arising in nondestructive testing by eddy currents. There are three chief methods used for calculating such induction phenomena: analytical boundary-value solutions, relaxation or iteration techniques, and model experiments. Some of the results obtained by each of these methods are described below

  17. Quantum phenomena in magnetic nano clusters

    Indian Academy of Sciences (India)

    While semiconductor structures have provided paradigms of nanosystems from the stand point of electronic phenomena, the synthesis of high nuclearity transition metal complexes have provided examples of nano magnets. The range and diversity of the properties exhibited by these systems rivals its electronic counterparts ...

  18. Hyperchaotic phenomena in dynamic decision making

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Mosekilde, Erik; Sterman, John David

    1992-01-01

    of this article is to show how the decision making behavior of real people in simulated corporate environments can lead to chaotic, hyperchaotic and higher-order hyperchaotic phenomena. Characteristics features of these complicated forms of behavior are analyzed with particular emphasis on an interesting form...

  19. Transport phenomena in materials processing---1990

    International Nuclear Information System (INIS)

    Bishop, B.J.; Lior, N.; Lavine, A.; Flik, M.; Karwe, M.V.; Bergman, T.L.; Beckermann, C.; Charmchi, M.

    1990-01-01

    The papers contained in this volume represent a wide range of current research interests in processes such as food and polymer processing, casting, welding, machining, laser cutting, and superconductor processing. This volume includes papers presented in four sessions: Heat Transfer in Materials Processing; Thermal Phenomena in Superconductor Processing; Heat Transfer in Food and Polymer Processing; Heat Transfer in CAsting and Welding

  20. Transport phenomena in strongly correlated Fermi liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kontani, Hiroshi [Nagoya Univ., Aichi (Japan). Dept. of Physics

    2013-03-01

    Comprehensive overview. Written by an expert of this topic. Provides the reader with current developments in the field. In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, {tau}, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical point using a uniform approach. We also discuss spin related transport phenomena in strongly correlated systems. In many d- and f-electron systems, the spin current induced by the spin Hall effect is considerably greater because of the orbital degrees of freedom. This fact attracts much attention due to its potential application in spintronics. We discuss various novel charge, spin and heat transport phenomena in strongly correlated metals.

  1. Quantum phenomena in magnetic nano clusters

    Indian Academy of Sciences (India)

    Unknown

    Abstract. One of the fascinating fields of study in magnetism in recent years has been the study of quantum phenomena in nanosystems. While semiconductor structures .... or discrete steps provided the sweep rate of the magnetic field is not too low 10. ... to the Landau–Zener two-level treatment within the spin-10 manifold.

  2. Imaging unsteady three-dimensional transport phenomena

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... physical domains with unsteady processes can be accommodated. Optical methods promise to breach the holy grail of measurements by extracting unsteady three-dimensional data in applications related to transport phenomena. Keywords. Optical measurement; fluid flow and transport; refractive index ...

  3. Movements of molecular motors: Ratchets, random walks and traffic phenomena

    Science.gov (United States)

    Klumpp, Stefan; Nieuwenhuizen, Theo M.; Lipowsky, Reinhard

    2005-10-01

    Processive molecular motors which drive the traffic of organelles in cells move in a directed way along cytoskeletal filaments. On large time scales, they perform motor walks, i.e., peculiar random walks which arise from the repeated unbinding from and rebinding to filaments. Unbound motors perform Brownian motion in the surrounding fluid. In addition, the traffic of molecular motors exhibits many cooperative phenomena. In particular, it faces similar problems as the traffic on streets such as the occurrence of traffic jams and the coordination of (two-way) traffic. These issues are studied here theoretically using lattice models.

  4. The use of suspension models and comparison with true weightlessness. [Animal Model Workshop on Gravitational Physiology

    Science.gov (United States)

    Musacchia, X. J.; Ellis, S.

    1985-01-01

    A resume is presented of various papers concerning the effect of weightlessness on particular physiological and biochemical phenomena in animal model systems. Findings from weightlessness experiments on earth using suspension models are compared with results of experiments in orbit. The biological phenomena considered include muscle atrophy, changes in the endocrine system, reduction in bone formation, and changes in the cardiovascular system.

  5. Surface Phenomena at Silver Nanoparticles in the Context of Toxicology

    DEFF Research Database (Denmark)

    Miclaus, Teodora

    2015-01-01

    is also observed in the third study, where transformation form metallic to sulphur-bound monovalent silver is shown inside cells. Ag nanoparticles are shown to dissolve much more rapidly inside cells than in cell culture medium and the ions are thought to bind to sulphur-containing proteins, disrupting...... associated with engineered nanomaterials. Among these materials, silver nanoparticles are some of the most widely employed and thus represent a major point of focus in nanotoxicology and the topic of this PhD thesis. While nanoparticles have, upon synthesis, well-defined characteristics, specific...... of nanotoxicology. The main aim of this PhD research is to investigate these phenomena at the surface of silver nanoparticles under conditions that are relevant for in vitro studies in order to understand their implications for nano-silver toxicity. Upon contact with biological fluids, particles get coated...

  6. Role of insulin hormone in modulation of inflammatory phenomena

    Directory of Open Access Journals (Sweden)

    Antonio Di Petta

    2011-09-01

    Full Text Available Evidence demonstrates the involvement of hormones in thedevelopment of inflammatory response. Inflammation evokes markedstructural alterations of microvasculature, besides migration ofleukocytes from microcirculation to the site of lesion. These alterations are caused primarily by release or activation of endogenous mediators, in which hormones play an integral role in this regulatory system. Binding sites for many hormones may be characterized by vascular structures and hematogenous cells involved with the inflammatory response. Quantitative alterations of inflammatory events involving the decrease in microvascular response to inflammatory mediators, deficiency in the leukocyte-endothelium interaction, reduction of cell concentration in the inflammatory exudate, and failure of the phagocyte function of mononuclear cells were observed in insulindeficient states. Therefore, inflammation is not merely a local response, but rather a process controlled by hormones in which insulin plays an essential role in modulation of these phenomena, and assures tissue repair and remodeling within the limits of normality.

  7. EDITORIAL A CASCADE OF BIOCHEMICAL AND PHYSIOLOGICAL ...

    African Journals Online (AJOL)

    pharm-chem

    A CASCADE OF BIOCHEMICAL AND PHYSIOLOGICAL MARKERS IN PATHOLOGICAL. DISORDERS. A few years ago, a neurophysiology lecturer in the Department of Medical Physiology, University of. Nairobi, was doing ... from haemolysis of RBC is rapidly distributed into cells and excreted in kidney. It would have been.

  8. PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media

    Science.gov (United States)

    Eikerling, Michael

    2011-06-01

    Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent

  9. Physiological Information Database (PID)

    Science.gov (United States)

    EPA has developed a physiological information database (created using Microsoft ACCESS) intended to be used in PBPK modeling. The database contains physiological parameter values for humans from early childhood through senescence as well as similar data for laboratory animal spec...

  10. A treatise on interpolar transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Einarsrud, Kristian Etienne

    2012-07-01

    This thesis contributes to the understanding of mechanisms for mass transport in aluminium electrolysis cells. Fundamental studies are undertaken of flow patterns and mass transport in the interpolar region under various operating conditions. A coupled model predicting the turbulent electrolyte flow, under the influence of both electromagnetism and forces from buoyant gas bubbles, crucial for better prediction of mass transfer mechanisms and voltage oscillations, has been developed from first principles. The model is validated against experiments performed on a lab scale electrolysis cell. Both modelling and experiments are performed within the scope of this thesis. Experiments on lab- and industrial scale cells have been conducted in order to study the behaviour of anodic gas bubbles under various operating conditions. On industrial scale, bubble related signals show typical frequencies in the range 0.5 to 2 Hz, with amplitudes up to 5% around the mean voltage. Results indicate that the bubble related voltage oscillations increase in both frequency and magnitude with increasing anode age, the latter of which due to the diminishing in influence of slots. No significant correlation between anode pairs is identified, suggesting that models treating individual anodes are meaningful also on an industrial scale. Due to challenges related to multiple simultaneous phenomena occurring on industrial scales, a series of lab scale measurements have been performed, in order to obtain quantitative data for model validation. The lab scale experimental cell allowed for different current densities, interpolar distances and inclination angles, thus spanning ranges typically encountered on the industrial scale. Lab scale frequencies are found to be in the range 0.25 to 0.65 Hz, with magnitude of up to 4% around the mean voltage. The magnitude of the oscillations decreases with increasing anode age, due to increased rounding of the initially sharp anode edges. The traditional voltage

  11. The impact of pH inhomogeneities on CHO cell physiology and fed-batch process performance - two-compartment scale-down modelling and intracellular pH excursion.

    Science.gov (United States)

    Brunner, Matthias; Braun, Philipp; Doppler, Philipp; Posch, Christoph; Behrens, Dirk; Herwig, Christoph; Fricke, Jens

    2017-07-01

    Due to high mixing times and base addition from top of the vessel, pH inhomogeneities are most likely to occur during large-scale mammalian processes. The goal of this study was to set-up a scale-down model of a 10-12 m 3 stirred tank bioreactor and to investigate the effect of pH perturbations on CHO cell physiology and process performance. Short-term changes in extracellular pH are hypothesized to affect intracellular pH and thus cell physiology. Therefore, batch fermentations, including pH shifts to 9.0 and 7.8, in regular one-compartment systems are conducted. The short-term adaption of the cells intracellular pH are showed an immediate increase due to elevated extracellular pH. With this basis of fundamental knowledge, a two-compartment system is established which is capable of simulating defined pH inhomogeneities. In contrast to state-of-the-art literature, the scale-down model is included parameters (e.g. volume of the inhomogeneous zone) as they might occur during large-scale processes. pH inhomogeneity studies in the two-compartment system are performed with simulation of temporary pH zones of pH 9.0. The specific growth rate especially during the exponential growth phase is strongly affected resulting in a decreased maximum viable cell density and final product titer. The gathered results indicate that even short-term exposure of cells to elevated pH values during large-scale processes can affect cell physiology and overall process performance. In particular, it could be shown for the first time that pH perturbations, which might occur during the early process phase, have to be considered in scale-down models of mammalian processes. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Plant Physiology in Greenhouses

    NARCIS (Netherlands)

    Heuvelink, E.; Kierkels, T.

    2015-01-01

    Since 2004 Ep Heuvelink and Tijs Kierkels have been writing a continuing series of plant physiology articles for the Dutch horticultural journal Onder Glas and the international edition In Greenhouses. The book Plant Physiology in Greenhouses consists of 50 of their plant physiology articles. The

  13. Basic transport phenomena in materials engineering

    CERN Document Server

    Iguchi, Manabu

    2014-01-01

    This book presents the basic theory and experimental techniques of transport phenomena in materials processing operations. Such fundamental knowledge is highly useful for researchers and engineers in the field to improve the efficiency of conventional processes or develop novel technology. Divided into four parts, the book comprises 11 chapters describing the principles of momentum transfer, heat transfer, and mass transfer in single phase and multiphase systems. Each chapter includes examples with solutions and exercises to facilitate students’ learning. Diagnostic problems are also provided at the end of each part to assess students’ comprehension of the material.  The book is aimed primarily at students in materials science and engineering. However, it can also serve as a useful reference text in chemical engineering as well as an introductory transport phenomena text in mechanical engineering. In addition, researchers and engineers engaged in materials processing operations will find the material use...

  14. Coherence Phenomena in Coupled Optical Resonators

    Science.gov (United States)

    Smith, D. D.; Chang, H.

    2004-01-01

    We predict a variety of photonic coherence phenomena in passive and active coupled ring resonators. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived, and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. We also demonstrate that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation, and use this result for the analysis of coupled-resonator photon dynamics. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators.

  15. Transport phenomena in strongly correlated Fermi liquids

    CERN Document Server

    Kontani, Hiroshi

    2013-01-01

    In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, \\tau, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical poi...

  16. Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

    Science.gov (United States)

    Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

    2017-09-01

    Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

  17. Dopamine in human follicular fluid is associated with cellular uptake and metabolism-dependent generation of reactive oxygen species in granulosa cells: implications for physiology and pathology.

    Science.gov (United States)

    Saller, S; Kunz, L; Berg, D; Berg, U; Lara, H; Urra, J; Hecht, S; Pavlik, R; Thaler, C J; Mayerhofer, A

    2014-03-01

    Is the neurotransmitter dopamine (DA) in the human ovary involved in the generation of reactive oxygen species (ROS)? Human ovarian follicular fluid contains DA, which causes the generation of ROS in cultured human granulosa cells (GCs), and alterations of DA levels in follicular fluid and DA uptake/metabolism in GCs in patients with polycystic ovary syndrome (PCOS) are linked to increased levels of ROS. DA is an important neurotransmitter in the brain, and the metabolism of DA results in the generation of ROS. DA was detected in human ovarian homogenates, but whether it is present in follicular fluid and plays a role in the follicle is not known. We used human follicular fluid from patients undergoing in vitro fertilization (IVF), GCs from patients with or without PCOS and also employed mathematical modeling to investigate the presence of DA and its effects on ROS. DA in follicular fluid and GCs was determined by enzyme-linked immunosorbent assay. GC viability, apoptosis and generation of ROS were monitored in GCs upon addition of DA. Inhibitors of DA uptake and metabolism, an antioxidant and DA receptor agonists, were used to study cellular uptake and the mechanism of DA-induced ROS generation. Human GCs were examined for the presence and abundance of transcripts of the DA transporter (DAT; SLC6A3), the DA-metabolizing enzymes monoamine oxidases A/B (MAO-A/B) and catechol-O-methyltransferase and the vesicular monoamine transporter. A computational model was developed to describe and predict DA-induced ROS generation in human GCs. We found DA in follicular fluid of ovulatory follicles of the human ovary and in GCs. DAT and MAO-A/B, which are expressed by GCs, are prerequisites for a DA receptor-independent generation of ROS in GCs. Blockers of DAT and MAO-A/B, as well as an antioxidant, prevented the generation of ROS (P human follicular compartment, functions of DA could only be studied in IVF-derived GCs, which can be viewed as a cellular model for the

  18. An introduction to the neutron transport phenomena

    International Nuclear Information System (INIS)

    Kulikowska, T.

    2001-01-01

    The main goal of the present lecture is to is to give a short description of neutron transport phenomena limited to those definitions that are necessary to understand the approach to practical solution of the problem given in the second lecture on reactor lattice transport calculations. The discussion of the neutron cross sections has been skipped as other lecturers have treated this subject in detail. (author)

  19. A LCIA Model Considering Pollution Transfer Phenomena

    OpenAIRE

    Yu, Xi; Sekhari, Aicha; Nongaillard, Antoine; Bouras, Abdelaziz; Yu, Suiran; Yang, Qingyan

    2013-01-01

    Part 7: PLM and Influence of/from Social Networks; International audience; Due to market pressure and government regulations, environmental consciousness in manufacturing is becoming increasingly important. Currently, the global environmental impact (EI) of a product is a crucial criterion to judge its environmental performance. Many models were proposed in the last three decades to evaluate the global EI of products, but none of them considers the pollution transfer phenomena (PTP) of produc...

  20. Natural phenomena hazards site characterization criteria

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    The criteria and recommendations in this standard shall apply to site characterization for the purpose of mitigating Natural Phenomena Hazards (wind, floods, landslide, earthquake, volcano, etc.) in all DOE facilities covered by DOE Order 5480.28. Criteria for site characterization not related to NPH are not included unless necessary for clarification. General and detailed site characterization requirements are provided in areas of meteorology, hydrology, geology, seismology, and geotechnical studies.

  1. Workshop on Nonlinear Phenomena in Complex Systems

    CERN Document Server

    1989-01-01

    This book contains a thorough treatment of neural networks, cellular-automata and synergetics, in an attempt to provide three different approaches to nonlinear phenomena in complex systems. These topics are of major interest to physicists active in the fields of statistical mechanics and dynamical systems. They have been developed with a high degree of sophistication and include the refinements necessary to work with the complexity of real systems as well as the more recent research developments in these areas.

  2. Occult Phenomena in Sherlock Holmes the Movie

    OpenAIRE

    NAMAZCARRA, CHRIESHER

    2014-01-01

    Keywords: Occult phenomena, Sherlock Holmes, movie. Lately, it is not difficult for people to find occult practices. There are many television programs and movie which air mystical programme aggressively to raise the rating and attract the viewers. A movie that raise occultism theme is Sherlock Holmes, the Movie. This movie tells about the struggle of detective Sherlock Holmes to fight the black magic power of Lord Blackwood.To carry out the study, the theories of Occultism such as the secrec...

  3. Attophysics of Thermal Phenomena in Carbon Nanotubes

    OpenAIRE

    Kozlowski, Miroslaw; Marciak-Kozlowska, Janina

    2005-01-01

    In this paper heat transport in carbon nanotubes is investigated. When the dimension of the structure is of the order of the de Broglie wave length transport phenomena must be analysed by quantum mechanics. In this paper we derived the Dirac type thermal equation .The solution of the equation for the temperature fields for electrons can either be damped or can oscillate depending on the dynamics of the scattering. Key words: Carbon nanotubes, ultrashort laser pulses, Dirac thermal equation, t...

  4. Guilt phenomena in medicine, psychology, and psychiatry

    OpenAIRE

    Germanavičius, Arūnas

    2014-01-01

    This article gives an overview of various aspects of guilt arising in psychiatry as an interdisciplinary field, where different conceptions of medical ethics and of psychology lead to different practices. The analysis of modern psychiatric phenomena of guilt using a historical approach is based on the concept of guilt expounded by one of the world’s greatest philosophers, Karl Theodor Jaspers, who has made a huge impact on the formation of psychiatric research. The author presents an original...

  5. Bion and Tustin: the autistic phenomena.

    Science.gov (United States)

    Korbivcher, Celia Fix

    2013-08-01

    This article examines the implications of the proposal of autistic transformations within the general context of Bion's theory of Transformations. The aim is to confirm the coherence of this proposal of autistic transformations within the overall structure of Bion's theory of Transformations. She examines the relation between emotional links and their negatives, particularly -K. She questions in which of the dimensions of the mind the autistic phenomena are located, the relation between autistic phenomena and beta elements, and where to place them in the Grid. The author tries to form metapsychological support for the incorporation of the autistic area in Bion's theory of Transformations. She argues that, despite the incongruence and imprecision of this incorporation, such autistic phenomena cannot be excluded from the complexus of the human mind and should therefore be accounted for in Bion's transformations. She discusses the idea that the theory of transformations includes the field of the neurosis and psychosis and deals with emotions, whereas the autistic area is dominated by sensations. The author asks how to add the autistic area to Bion's theory. Clinical material of a child for whom the non-psychotic part of the personality predominates and who presents autistic nuclei provides material for the discussion. Copyright © 2013 Institute of Psychoanalysis.

  6. Quantum Chess: Making Quantum Phenomena Accessible

    Science.gov (United States)

    Cantwell, Christopher

    Quantum phenomena have remained largely inaccessible to the general public. There tends to be a scare factor associated with the word ``Quantum''. This is in large part due to the alien nature of phenomena such as superposition and entanglement. However, Quantum Computing is a very active area of research and one day we will have games that run on those quantum computers. Quantum phenomena such as superposition and entanglement will seem as normal as gravity. Is it possible to create such games today? Can we make games that are built on top of a realistic quantum simulation and introduce players of any background to quantum concepts in a fun and mentally stimulating way? One of the difficulties with any quantum simulation run on a classical computer is that the Hilbert space grows exponentially, making simulations of an appreciable size physically impossible due largely to memory restrictions. Here we will discuss the conception and development of Quantum Chess, and how to overcome some of the difficulties faced. We can then ask the question, ``What's next?'' What are some of the difficulties Quantum Chess still faces, and what is the future of quantum games?

  7. An interpretation of passive containment cooling phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Bum-Jin [Ministry of Science & Technology, Kyunggi-Do (Korea, Democratic People`s Republic of); Kang, Chang-Sun, [Seoul National Univ. (Korea, Democratic People`s Republic of)

    1995-09-01

    A simplified interpretation model for the cooling capability of the Westinghouse type PCCS is proposed in this paper. The PCCS domain was phenomenologically divided into 3 regions; water entrance effect region, asymptotic region, and air entrance effect region. The phenomena in the asymptotic region is focused in this paper. Due to the very large height to thickness ratio of the water film, the length of the asymptotic region is estimated to be over 90% of the whole domain. Using the analogy between heat and mass transfer phenomena in a turbulent situation, a new dependent variable combining temperature and vapor mass fraction was defined. The similarity between the PCCS phenomena, which contains the sensible and latent heat transfer, and the buoyant air flow on a vertical heated plate is derived. The modified buoyant coefficient and thermal conductivity were defined. Using these newly defined variable and coefficients, the modified correlation for the interfacial heat fluxes and the ratios of latent heat transfer to sensible heat transfer is established. To verify the accuracy of the correlation, the results of this study were compared with the results of other numerical analyses performed for the same configuration and they are well within the range of 15% difference.

  8. Thermal transport phenomena in nanoparticle suspensions

    International Nuclear Information System (INIS)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-01-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications. (topical review)

  9. Thermal transport phenomena in nanoparticle suspensions

    Science.gov (United States)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-12-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications.

  10. Smolt physiology and endocrinology

    Science.gov (United States)

    McCormick, Stephen D.; McCormick, Stephen D.; Farrell, Anthony Peter; Brauner, Colin J.

    2013-01-01

    Hormones play a critical role in maintaining body fluid balance in euryhaline fishes during changes in environmental salinity. The neuroendocrine axis senses osmotic and ionic changes, then signals and coordinates tissue-specific responses to regulate water and ion fluxes. Rapid-acting hormones, e.g. angiotensins, cope with immediate challenges by controlling drinking rate and the activity of ion transporters in the gill, gut, and kidney. Slow-acting hormones, e.g. prolactin and growth hormone/insulin-like growth factor-1, reorganize the body for long-term acclimation by altering the abundance of ion transporters and through cell proliferation and differentiation of ionocytes and other osmoregulatory cells. Euryhaline species exist in all groups of fish, including cyclostomes, and cartilaginous and teleost fishes. The diverse strategies for responding to changes in salinity have led to differential regulation and tissue-specific effects of hormones. Combining traditional physiological approaches with genomic, transcriptomic, and proteomic analyses will elucidate the patterns and diversity of the endocrine control of euryhalinity.

  11. Polyamines in plant physiology

    Science.gov (United States)

    Galston, A. W.; Sawhney, R. K.

    1990-01-01

    The diamine putrescine, the triamine spermidine, and the tetramine spermine are ubiquitous in plant cells, while other polyamines are of more limited occurrence. Their chemistry and pathways of biosynthesis and metabolism are well characterized. They occur in the free form as cations, but are often conjugated to small molecules like phenolic acids and also to various macromolecules. Their titer varies from approximately micromolar to more than millimolar, and depends greatly on environmental conditions, especially stress. In cereals, the activity of one of the major polyamine biosynthetic enzymes, arginine decarboxylase, is rapidly and dramatically increased by almost every studied external stress, leading to 50-fold or greater increases in putrescine titer within a few hours. The physiological significance of this increase is not yet clear, although most recent work suggests an adaptive, protective role. Polyamines produced through the action of ornithine decarboxylase, by contrast, seem essential for DNA replication and cell division. The application of exogenous polyamines produces effects on patterns of senescence and morphogenesis, suggesting but not proving a regulatory role for polyamines in these processes. The evidence for such a regulatory role is growing.

  12. Physiological and pathological consequences of cellular senescence

    OpenAIRE

    Burton, Dominick G. A.; Krizhanovsky, Valery

    2014-01-01

    Cellular senescence, a permanent state of cell cycle arrest accompanied by a complex phenotype, is an essential mechanism that limits tumorigenesis and tissue damage. In physiological conditions, senescent cells can be removed by the immune system, facilitating tumor suppression and wound healing. However, as we age, senescent cells accumulate in tissues, either because an aging immune system fails to remove them, the rate of senescent cell formation is elevated, or both. If senescent cells p...

  13. Doppler radar physiological sensing

    CERN Document Server

    Lubecke, Victor M; Droitcour, Amy D; Park, Byung-Kwon; Singh, Aditya

    2016-01-01

    Presents a comprehensive description of the theory and practical implementation of Doppler radar-based physiological monitoring. This book includes an overview of current physiological monitoring techniques and explains the fundamental technology used in remote non-contact monitoring methods. Basic radio wave propagation and radar principles are introduced along with the fundamentals of physiological motion and measurement. Specific design and implementation considerations for physiological monitoring radar systems are then discussed in detail. The authors address current research and commercial development of Doppler radar based physiological monitoring for healthcare and other applications.

  14. Human factors estimation methods using physiological informations

    International Nuclear Information System (INIS)

    Takano, Ken-ichi; Yoshino, Kenji; Nakasa, Hiroyasu

    1984-01-01

    To enhance the operational safety in the nuclear power plant, it is necessary to decrease abnormal phenomena due to human errors. Especially, it is essential to basically understand human behaviors under the work environment for plant maintenance workers, inspectors, and operators. On the above stand point, this paper presents the results of literature survey on the present status of human factors engineering technology applicable to the nuclear power plant and also discussed the following items: (1) Application fields where the ergonomical evaluation is needed for workers safety. (2) Basic methodology for investigating the human performance. (3) Features of the physiological information analysis among various types of ergonomical techniques. (4) Necessary conditions for the application of in-situ physiological measurement to the nuclear power plant. (5) Availability of the physiological information analysis. (6) Effectiveness of the human factors engineering methodology, especially physiological information analysis in the case of application to the nuclear power plant. The above discussions lead to the demonstration of high applicability of the physiological information analysis to nuclear power plant, in order to improve the work performance. (author)

  15. Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

    KAUST Repository

    Tsai, Yu-Lin

    2016-09-06

    Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via nanoscaled phenomena have also been demonstrated as a promising way for further modifying/improving the device performance. The accomplishments achieved by photon management via nanoscaled phenomena include strain-induced polarization field management, crystal quality improvement, light extraction/harvesting enhancement, radiation pattern control, and spectrum management. In this review, we summarize recent development, challenges and underlying physics of photon management in GaN-based light emitting diodes and solar cells. (C) 2016 Elsevier Ltd. All rights reserved.

  16. Cardiovascular physiology misconceptions and the potential of cardiovascular physiology teaching to alleviate these.

    Science.gov (United States)

    Palizvan, Mohammad Reza; Nejad, Mohammad Reza Taheri; Jand, Abolfazl; Rafeie, Mohammad

    2013-06-01

    Misconceptions are mental models of phenomena that are at variance with accepted scientific models of these phenomena. The goal of this study was to investigate the prevalence of some misconceptions among students about cardiovascular physiology and to evaluate the effectiveness of cardiovascular physiology teaching in alleviating these misconceptions. A descriptive-analytic survey was undertaken with 348 undergraduates from the fields of medicine, nursing, and biology. Students were divided into two groups on the basis of whether they had passed or not taken the cardiovascular physiology course. The students were asked to answer four questions relating to cardiovascular. Descriptive statistic analysis and two-tailed comparison of the proportions was used to analyze their answers. The prevalence of misconceptions about the left ventricular output versus the right ventricular output ranged from 80% to 98%. The misconception about pulse velocity compared with blood velocity in the vessels was 74% to 89%. Between 95% and 99% of answers to the effect of increased resistance on blood flow were incorrect in all groups. Between 69% and 73% of the students had trouble answering the question on parallel resistance and the effect of the removal of one limb on total peripheral resistance. For most of the questions, university lectures had no effect on alleviating these misconceptions. These results indicate that there is a high prevalence of misconceptions among students about at least four cardiovascular concepts associated with cardiovascular physiology and that teaching has failed to alleviate these misconceptions.

  17. Studies of Novel Quantum Phenomena in Ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Zhiqiang

    2011-04-08

    Strongly correlated oxides have been the subject of intense study in contemporary condensed matter physics, and perovskite ruthenates (Sr,Ca)n+1RunO3n+1 have become a new focus in this field. One of important characteristics of ruthenates is that both lattice and orbital degrees of freedom are active and are strongly coupled to charge and spin degrees of freedom. Such a complex interplay of multiple degrees of freedom causes the properties of ruthenates to exhibit a gigantic response to external stimuli under certain circumstances. Magnetic field, pressure, and chemical composition all have been demonstrated to be effective in inducing electronic/magnetic phase transitions in ruthenates. Therefore, ruthenates are ideal candidates for searching for novel quantum phenomena through controlling external parameters. The objective of this project is to search for novel quantum phenomena in ruthenate materials using high-quality single crystals grown by the floating-zone technique, and investigate the underlying physics. The following summarizes our accomplishments. We have focused on trilayered Sr4Ru3O10 and bilayered (Ca1-xSrx)3Ru2O7. We have succeeded in growing high-quality single crystals of these materials using the floating-zone technique and performed systematic studies on their electronic and magnetic properties through a variety of measurements, including resistivity, Hall coefficient, angle-resolved magnetoresistivity, Hall probe microscopy, and specific heat. We have also studied microscopic magnetic properties for some of these materials using neutron scattering in collaboration with Los Alamos National Laboratory. We have observed a number of unusual exotic quantum phenomena through these studies, such as an orbital selective metamagnetic transition, bulk spin valve effect, and a heavy-mass nearly ferromagnetic state with a surprisingly large Wilson ratio. Our work has also revealed underlying physics of these exotic phenomena. Exotic phenomena of correlated

  18. ACCIDENT PHENOMENA OF RISK IMPORTANCE PROJECT - Continued RESEARCH CONCERNING SEVERE ACCIDENT PHENOMENA AND MANAGEMENT IN Sweden

    International Nuclear Information System (INIS)

    Rolandson, S.; Mueller, F.; Loevenhielm, G.

    1997-01-01

    Since 1988 all reactors in Sweden have mitigating measures, such as filtered vents, implemented. In parallel with the work of implementing these measures, a cooperation effort (RAMA projects) between the Swedish utilities and the Nuclear Power Inspectorate was performed to acquire sufficient knowledge about severe accident research work. The on-going project has the name Accident Phenomena of Risk Importance 3. In this paper, we will give background information about severe accident management in Sweden. In the Accident Phenomena of Risk Importance 3 project we will focus on the work concerning coolability of melted core in lower plenum which is the main focus of the In-vessel Coolability Task Group within the Accident Phenomena of Risk Importance 3 project. The Accident Phenomena of Risk Importance 3 project has joined on international consortium and the in-vessel cooling experiments are performed by Fauske and Associates, Inc. in Burr Ridge, Illinois, United States America, Sweden also intends to do one separate experiment with one instrument penetration we have in Swedish/Finnish BWR's. Other parts of the Accident Phenomena of Risk Importance 3 project, such as support to level 2 studies, the research at Royal Institute of Technology and participation in international programs, such as Cooperative Severe Accident Research Program, Advanced Containment Experiments and PHEBUS will be briefly described in the paper

  19. BWR core melt progression phenomena: Experimental analyses

    International Nuclear Information System (INIS)

    Ott, L.J.

    1992-01-01

    In the BWR Core Melt in Progression Phenomena Program, experimental results concerning severe fuel damage and core melt progression in BWR core geometry are used to evaluate existing models of the governing phenomena. These include control blade eutectic liquefaction and the subsequent relocation and attack on the channel box structure; oxidation heating and hydrogen generation; Zircaloy melting and relocation; and the continuing oxidation of zirconium with metallic blockage formation. Integral data have been obtained from the BWR DF-4 experiment in the ACRR and from BWR tests in the German CORA exreactor fuel-damage test facility. Additional integral data will be obtained from new CORA BWR test, the full-length FLHT-6 BWR test in the NRU test reactor, and the new program of exreactor experiments at Sandia National Laboratories (SNL) on metallic melt relocation and blockage formation. an essential part of this activity is interpretation and use of the results of the BWR tests. The Oak Ridge National Laboratory (ORNL) has developed experiment-specific models for analysis of the BWR experiments; to date, these models have permitted far more precise analyses of the conditions in these experiments than has previously been available. These analyses have provided a basis for more accurate interpretation of the phenomena that the experiments are intended to investigate. The results of posttest analyses of BWR experiments are discussed and significant findings from these analyses are explained. The ORNL control blade/canister models with materials interaction, relocation and blockage models are currently being implemented in SCDAP/RELAP5 as an optional structural component

  20. In vessel core melt progression phenomena

    International Nuclear Information System (INIS)

    Courtaud, M.

    1993-01-01

    For all light water reactor (LWR) accidents, including the so called severe accidents where core melt down can occur, it is necessary to determine the amount and characteristics of fission products released to the environment. For existing reactors this knowledge is used to evaluate the consequences and eventual emergency plans. But for future reactors safety authorities demand decrease risks and reactors designed in such a way that fission products are retained inside the containment, the last protective barrier. This requires improved understanding and knowledge of all accident sequences. In particular it is necessary to be able to describe the very complex phenomena occurring during in vessel core melt progression because they will determine the thermal and mechanical loads on the primary circuit and the timing of its rupture as well as the fission product source term. On the other hand, in case of vessel failure, knowledge of the physical and chemical state of the core melt will provide the initial conditions for analysis of ex-vessel core melt progression and phenomena threatening the containment. Finally a good understanding of in vessel phenomena will help to improve accident management procedures like Emergency Core Cooling System water injection, blowdown and flooding of the vessel well, with their possible adverse effects. Research and Development work on this subject was initiated a long time ago and is still in progress but now it must be intensified in order to meet the safety requirements of the next generation of reactors. Experiments, limited in scale, analysis of the TMI 2 accident which is a unique source of global information and engineering judgment are used to establish a