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Sample records for cell model system

  1. Modeling fuel cell stack systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J H [Los Alamos National Lab., Los Alamos, NM (United States); Lalk, T R [Dept. of Mech. Eng., Texas A and M Univ., College Station, TX (United States)

    1998-06-15

    A technique for modeling fuel cell stacks is presented along with the results from an investigation designed to test the validity of the technique. The technique was specifically designed so that models developed using it can be used to determine the fundamental thermal-physical behavior of a fuel cell stack for any operating and design configuration. Such models would be useful tools for investigating fuel cell power system parameters. The modeling technique can be applied to any type of fuel cell stack for which performance data is available for a laboratory scale single cell. Use of the technique is demonstrated by generating sample results for a model of a Proton Exchange Membrane Fuel Cell (PEMFC) stack consisting of 125 cells each with an active area of 150 cm{sup 2}. A PEMFC stack was also used in the verification investigation. This stack consisted of four cells, each with an active area of 50 cm{sup 2}. Results from the verification investigation indicate that models developed using the technique are capable of accurately predicting fuel cell stack performance. (orig.)

  2. Simplified fuel cell system model identification

    Energy Technology Data Exchange (ETDEWEB)

    Caux, S.; Fadel, M. [Laboratoire d' Electrotechnique et d' Electronique Industrielle, Toulouse (France); Hankache, W. [Laboratoire d' Electrotechnique et d' Electronique Industrielle, Toulouse (France)]|[Laboratoire de recherche en Electronique, Electrotechnique et Systemes, Belfort (France); Hissel, D. [Laboratoire de recherche en Electronique, Electrotechnique et Systemes, Belfort (France)

    2006-07-01

    This paper discussed a simplified physical fuel cell model used to study fuel cell and supercap energy applications for vehicles. Anode, cathode, membrane, and electrode elements of the cell were modelled. A quasi-static Amphlett model was used to predict voltage responses of the fuel cell as a function of the current, temperature, and partial pressures of the reactive gases. The potential of each cell was multiplied by the number of cells in order to model a fuel cell stack. The model was used to describe the main phenomena associated with current voltage behaviour. Data were then compared with data from laboratory tests conducted on a 20 cell stack subjected to a current and time profile developed using speed data from a vehicle operating in an urban environment. The validated model was used to develop iterative optimization algorithms for an energy management strategy that linked 3 voltage sources with fuel cell parameters. It was concluded that classic state and dynamic measurements using a simple least square algorithm can be used to identify the most important parameters for optimal fuel cell operation. 9 refs., 1 tab., 6 figs.

  3. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...... cell systems. Consequences of indirectly fueling PEM stacks with hydrocarbons using reforming technology were investigated using a PEM stack model including CO poisoning kinetics and a transient Simulink steam reforming system model. Aspects regarding the optimization of PEM fuel cell systems...

  4. System level modeling and component level control of fuel cells

    Science.gov (United States)

    Xue, Xingjian

    This dissertation investigates the fuel cell systems and the related technologies in three aspects: (1) system-level dynamic modeling of both PEM fuel cell (PEMFC) and solid oxide fuel cell (SOFC); (2) condition monitoring scheme development of PEM fuel cell system using model-based statistical method; and (3) strategy and algorithm development of precision control with potential application in energy systems. The dissertation first presents a system level dynamic modeling strategy for PEM fuel cells. It is well known that water plays a critical role in PEM fuel cell operations. It makes the membrane function appropriately and improves the durability. The low temperature operating conditions, however, impose modeling difficulties in characterizing the liquid-vapor two phase change phenomenon, which becomes even more complex under dynamic operating conditions. This dissertation proposes an innovative method to characterize this phenomenon, and builds a comprehensive model for PEM fuel cell at the system level. The model features the complete characterization of multi-physics dynamic coupling effects with the inclusion of dynamic phase change. The model is validated using Ballard stack experimental result from open literature. The system behavior and the internal coupling effects are also investigated using this model under various operating conditions. Anode-supported tubular SOFC is also investigated in the dissertation. While the Nernst potential plays a central role in characterizing the electrochemical performance, the traditional Nernst equation may lead to incorrect analysis results under dynamic operating conditions due to the current reverse flow phenomenon. This dissertation presents a systematic study in this regard to incorporate a modified Nernst potential expression and the heat/mass transfer into the analysis. The model is used to investigate the limitations and optimal results of various operating conditions; it can also be utilized to perform the

  5. THE PROGRAMED CELL DEATH REGULATORS OF ISOLATED MODEL SYSTEMS

    Directory of Open Access Journals (Sweden)

    D. V. Vatlitsov

    2016-06-01

    Full Text Available The technology evolution creates the prerequisites for the emergence of new informational concept and approaches to the formation of a fundamentally new principles of biological objects understanding. The aim was to study the activators of the programmed cell death in an isolated system model. Cell culture aging parameters were performed on flow cytometer. It had formed the theory that the changes in the concentrations of metal ions and increase their extracellular concentration had formed a negative gradient into the cells.regulation of cell death. It was shown that the metals ions concentrations.

  6. Multivariable control system for dynamic PEM fuel cell model

    International Nuclear Information System (INIS)

    Tanislav, Vasile; Carcadea, Elena; Capris, Catalin; Culcer, Mihai; Raceanu, Mircea

    2010-01-01

    Full text: The main objective of this work was to develop a multivariable control system of robust type for a PEM fuel cells assembly. The system will be used in static and mobile applications for different values of power, generated by a fuel cell assembly of up to 10 kW. Intermediate steps were accomplished: a study of a multivariable control strategy for a PEM fuel cell assembly; a mathematic modeling of mass and heat transfer inside of fuel cell assembly, defining the response function to hydrogen and oxygen/air mass flow and inlet pressure changes; a testing stand for fuel cell assembly; experimental determinations of transient response for PEM fuel cell assembly, and more others. To define the multivariable control system for a PEM fuel cell assembly the parameters describing the system were established. Also, there were defined the generic mass and energy balance equations as functions of derivative of m i , in and m i , out , representing the mass going into and out from the fuel cell, while Q in is the enthalpy and Q out is the enthalpy of the unused reactant gases and heat produced by the product, Q dis is the heat dissipated to the surroundings, Q c is the heat taken away from the stack by active cooling and W el is the electricity generated. (authors)

  7. Multiway modeling and analysis in stem cell systems biology

    Directory of Open Access Journals (Sweden)

    Vandenberg Scott L

    2008-07-01

    Full Text Available Abstract Background Systems biology refers to multidisciplinary approaches designed to uncover emergent properties of biological systems. Stem cells are an attractive target for this analysis, due to their broad therapeutic potential. A central theme of systems biology is the use of computational modeling to reconstruct complex systems from a wealth of reductionist, molecular data (e.g., gene/protein expression, signal transduction activity, metabolic activity, etc.. A number of deterministic, probabilistic, and statistical learning models are used to understand sophisticated cellular behaviors such as protein expression during cellular differentiation and the activity of signaling networks. However, many of these models are bimodal i.e., they only consider row-column relationships. In contrast, multiway modeling techniques (also known as tensor models can analyze multimodal data, which capture much more information about complex behaviors such as cell differentiation. In particular, tensors can be very powerful tools for modeling the dynamic activity of biological networks over time. Here, we review the application of systems biology to stem cells and illustrate application of tensor analysis to model collagen-induced osteogenic differentiation of human mesenchymal stem cells. Results We applied Tucker1, Tucker3, and Parallel Factor Analysis (PARAFAC models to identify protein/gene expression patterns during extracellular matrix-induced osteogenic differentiation of human mesenchymal stem cells. In one case, we organized our data into a tensor of type protein/gene locus link × gene ontology category × osteogenic stimulant, and found that our cells expressed two distinct, stimulus-dependent sets of functionally related genes as they underwent osteogenic differentiation. In a second case, we organized DNA microarray data in a three-way tensor of gene IDs × osteogenic stimulus × replicates, and found that application of tensile strain to a

  8. Empirical membrane lifetime model for heavy duty fuel cell systems

    Science.gov (United States)

    Macauley, Natalia; Watson, Mark; Lauritzen, Michael; Knights, Shanna; Wang, G. Gary; Kjeang, Erik

    2016-12-01

    Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the ultimate heavy duty fuel cell lifetime target of 25,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log-linear Weibull life-stress statistical distribution. The obtained model is capable of extrapolating the membrane lifetime from accelerated test conditions to use level conditions during field operation. Based on typical conditions for the Whistler, British Columbia fuel cell transit bus fleet, the model predicts a stack lifetime of 17,500 h and a membrane leak initiation time of 9200 h. Validation performed with the aid of a field operated stack confirmed the initial goal of the model to predict membrane lifetime within 20% of the actual operating time.

  9. Model-based fault diagnosis in PEM fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Escobet, T; de Lira, S; Puig, V; Quevedo, J [Automatic Control Department (ESAII), Universitat Politecnica de Catalunya (UPC), Rambla Sant Nebridi 10, 08222 Terrassa (Spain); Feroldi, D; Riera, J; Serra, M [Institut de Robotica i Informatica Industrial (IRI), Consejo Superior de Investigaciones Cientificas (CSIC), Universitat Politecnica de Catalunya (UPC) Parc Tecnologic de Barcelona, Edifici U, Carrer Llorens i Artigas, 4-6, Planta 2, 08028 Barcelona (Spain)

    2009-07-01

    In this work, a model-based fault diagnosis methodology for PEM fuel cell systems is presented. The methodology is based on computing residuals, indicators that are obtained comparing measured inputs and outputs with analytical relationships, which are obtained by system modelling. The innovation of this methodology is based on the characterization of the relative residual fault sensitivity. To illustrate the results, a non-linear fuel cell simulator proposed in the literature is used, with modifications, to include a set of fault scenarios proposed in this work. Finally, it is presented the diagnosis results corresponding to these fault scenarios. It is remarkable that with this methodology it is possible to diagnose and isolate all the faults in the proposed set in contrast with other well known methodologies which use the binary signature matrix of analytical residuals and faults. (author)

  10. Evolving cell models for systems and synthetic biology.

    Science.gov (United States)

    Cao, Hongqing; Romero-Campero, Francisco J; Heeb, Stephan; Cámara, Miguel; Krasnogor, Natalio

    2010-03-01

    This paper proposes a new methodology for the automated design of cell models for systems and synthetic biology. Our modelling framework is based on P systems, a discrete, stochastic and modular formal modelling language. The automated design of biological models comprising the optimization of the model structure and its stochastic kinetic constants is performed using an evolutionary algorithm. The evolutionary algorithm evolves model structures by combining different modules taken from a predefined module library and then it fine-tunes the associated stochastic kinetic constants. We investigate four alternative objective functions for the fitness calculation within the evolutionary algorithm: (1) equally weighted sum method, (2) normalization method, (3) randomly weighted sum method, and (4) equally weighted product method. The effectiveness of the methodology is tested on four case studies of increasing complexity including negative and positive autoregulation as well as two gene networks implementing a pulse generator and a bandwidth detector. We provide a systematic analysis of the evolutionary algorithm's results as well as of the resulting evolved cell models.

  11. A cell-based model system links chromothripsis with hyperploidy

    DEFF Research Database (Denmark)

    Mardin, Balca R; Drainas, Alexandros P; Waszak, Sebastian M

    2015-01-01

    A remarkable observation emerging from recent cancer genome analyses is the identification of chromothripsis as a one-off genomic catastrophe, resulting in massive somatic DNA structural rearrangements (SRs). Largely due to lack of suitable model systems, the mechanistic basis of chromothripsis h...... in hyperploid cells. Analysis of primary medulloblastoma cancer genomes verified the link between hyperploidy and chromothripsis in vivo. CAST provides the foundation for mechanistic dissection of complex DNA rearrangement processes....

  12. Thermal System Modeling for Lunar and Martian Surface Regenerative Fuel Cell Systems

    Science.gov (United States)

    Gilligan, Ryan Patrick; Smith, Phillip James; Jakupca, Ian Joseph; Bennett, William Raymond; Guzik, Monica Christine; Fincannon, Homer J.

    2017-01-01

    The Advanced Exploration Systems (AES) Advanced Modular Power Systems (AMPS) Project is investigating different power systems for various lunar and Martian mission concepts. The AMPS Fuel Cell (FC) team has created two system-level models to evaluate the performance of regenerative fuel cell (RFC) systems employing different fuel cell chemistries. Proton Exchange Membrane fuel cells PEMFCs contain a polymer electrolyte membrane that separates the hydrogen and oxygen cavities and conducts hydrogen cations (protons) across the cell. Solid Oxide fuel cells (SOFCs) operate at high temperatures, using a zirconia-based solid ceramic electrolyte to conduct oxygen anions across the cell. The purpose of the modeling effort is to down select one fuel cell chemistry for a more detailed design effort. Figures of merit include the system mass, volume, round trip efficiency, and electrolyzer charge power required. PEMFCs operate at around 60 degrees Celsius versus SOFCs which operate at temperatures greater than 700 degrees Celsius. Due to the drastically different operating temperatures of the two chemistries the thermal control systems (TCS) differ. The PEM TCS is less complex and is characterized by a single pump cooling loop that uses deionized water coolant and rejects heat generated by the system to the environment via a radiator. The solid oxide TCS has its own unique challenges including the requirement to reject high quality heat and to condense the steam produced in the reaction. This paper discusses the modeling of thermal control systems for an extraterrestrial RFC that utilizes either a PEM or solid oxide fuel cell.

  13. System-level modeling and simulation of the cell culture microfluidic biochip ProCell

    DEFF Research Database (Denmark)

    Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan

    2010-01-01

    Microfluidic biochips offer a promising alternative to a conventional biochemical laboratory. There are two technologies for the microfluidic biochips: droplet-based and flow-based. In this paper we are interested in flow-based microfluidic biochips, where the liquid flows continuously through pre......-defined micro-channels using valves and pumps. We present an approach to the system-level modeling and simulation of a cell culture microfluidic biochip called ProCell, Programmable Cell Culture Chip. ProCell contains a cell culture chamber, which is envisioned to run 256 simultaneous experiments (viewed...

  14. Micrasterias as a model system in plant cell biology

    Directory of Open Access Journals (Sweden)

    Ursula Luetz-Meindl

    2016-07-01

    Full Text Available The unicellular freshwater alga Micrasterias denticulata is an exceptional organism due to its extraordinary star-shaped, highly symmetric morphology and has thus attracted the interest of researchers for many decades. As a member of the Streptophyta, Micrasterias is not only genetically closely related to higher land plants but shares common features with them in many physiological and cell biological aspects. These facts, together with its considerable cell size of about 200 µm, its modest cultivation conditions and the uncomplicated accessibility particularly to any microscopic techniques, make Micrasterias a very well suited cell biological plant model system. The review focuses particularly on cell wall formation and composition, dictyosomal structure and function, cytoskeleton control of growth and morphogenesis as well as on ionic regulation and signal transduction. It has been also shown in the recent years that Micrasterias is a highly sensitive indicator for environmental stress impact such as heavy metals, high salinity, oxidative stress or starvation. Stress induced organelle degradation, autophagy, adaption and detoxification mechanisms have moved in the center of interest and have been investigated with modern microscopic techniques such as 3-D- and analytical electron microscopy as well as with biochemical, physiological and molecular approaches. This review is intended to summarize and discuss the most important results obtained in Micrasterias in the last 20 years and to compare the results to similar processes in higher plant cells.

  15. Modeling of Pem Fuel Cell Systems Including Controls and Reforming Effects for Hybrid Automotive Applications

    National Research Council Canada - National Science Library

    Boettner, Daisie

    2001-01-01

    .... This study develops models for a stand-alone Proton Exchange Membrane (PEM) fuel cell stack, a direct-hydrogen fuel cell system including auxiliaries, and a methanol reforming fuel cell system for integration into a vehicle performance simulator...

  16. Muscle Stem Cells: A Model System for Adult Stem Cell Biology.

    Science.gov (United States)

    Cornelison, Ddw; Perdiguero, Eusebio

    2017-01-01

    Skeletal muscle stem cells, originally termed satellite cells for their position adjacent to differentiated muscle fibers, are absolutely required for the process of skeletal muscle repair and regeneration. In the last decade, satellite cells have become one of the most studied adult stem cell systems and have emerged as a standard model not only in the field of stem cell-driven tissue regeneration but also in stem cell dysfunction and aging. Here, we provide background in the field and discuss recent advances in our understanding of muscle stem cell function and dysfunction, particularly in the case of aging, and the potential involvement of muscle stem cells in genetic diseases such as the muscular dystrophies.

  17. Characterization and Modeling of a Methanol Reforming Fuel Cell System

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    topologies is the Reformed Methanol Fuel Cell (RMFC) system that operates on a mix of methanol and water. The fuel is reformed with a steam reforming to a hydrogen rich gas, however with additional formation of Carbon Monoxide and Carbon Dioxide. High Temperature Polymer Electrolyte Membrane Fuel Cell (HT...... to heat up the steam reforming process. However, utilizing the excess hydrogen in the system complicates the RMFC system as the amount of hydrogen can vary depending on the fuel methanol supply, fuel cell load and the reformer gas composition. This PhD study has therefore been involved in investigating......Many fuel cells systems today are operated with compressed hydrogen which has great benefits because of the purity of the hydrogen and the relatively simple storage of the fuel. However, compressed hydrogen is stored in the range of 800 bar, which can be expensive to compress.One of the interesting...

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

    Science.gov (United States)

    Suh, Kyung Won

    Transient performance is a key characteristic of fuel cells, that is sometimes more critical than efficiency, due to the importance of accepting unpredictable electric loads. To fulfill the transient requirement in vehicle propulsion and portable fuel cell applications, a fuel cell stack is typically coupled with a battery through a DC/DC converter to form a hybrid power system. Although many power management strategies already exist, they all rely on low level controllers that realize the power split. In this dissertation we design controllers that realize various power split strategies by directly manipulating physical actuators (low level commands). We maintain the causality of the electric dynamics (voltage and current) and investigate how the electric architecture affects the hybridization level and the power management. We first establish the performance limitations associated with a stand-alone and power-autonomous fuel cell system that is not supplemented by an additional energy storage and powers all its auxiliary components by itself. Specifically, we examine the transient performance in fuel cell power delivery as it is limited by the air supplied by a compressor driven by the fuel cell itself. The performance limitations arise from the intrinsic coupling in the fluid and electrical domain between the compressor and the fuel cell stack. Feedforward and feedback control strategies are used to demonstrate these limitations analytically and with simulations. Experimental tests on a small commercial fuel cell auxiliary power unit (APU) confirm the dynamics and the identified limitations. The dynamics associated with the integration of a fuel cell system and a DC/DC converter is then investigated. Decentralized and fully centralized (using linear quadratic techniques) controllers are designed to regulate the power system voltage and to prevent fuel cell oxygen starvation. Regulating these two performance variables is a difficult task and requires a compromise

  19. Triple co-culture cell model as an in vitro model for oral particulate vaccine systems

    DEFF Research Database (Denmark)

    Nielsen, Line Hagner; De Rossi, C.; Lehr, C-M.

    ; this was not observed with ovalbumin and blank solution. An example of the results is shown in Figure 2 for IL-17A. An established co-culture of Caco-2, THP-1 and MUTZ-3 cells showed promise as an in vitro model for testing of oral vaccine formulations. Mobility of co-culture immune cells as well as cytokine production......A triple co-culture cell model of Caco-2 cells, dendritic cells and macrophages (Figure 1) has previously been developed for studying intestinal permeability in a state of inflammation [1],[2]. The aim of this study was to investigate the applicability of this cell model for testing...... the model antigen ovalbumin was spray dried to obtain a particulate vaccine model system for testing in the cell model. The precursors were shown to form cubosomes when dispersed in aqueous medium, and was therefore used as the vaccine formulation for testing on the co-cultures. After 11 days, the TEER...

  20. Systems, methods and computer-readable media for modeling cell performance fade of rechargeable electrochemical devices

    Science.gov (United States)

    Gering, Kevin L

    2013-08-27

    A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics of the electrochemical cell. The computing system also develops a mechanistic level model of the electrochemical cell to determine performance fade characteristics of the electrochemical cell and analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell. The mechanistic level model uses first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density. The mechanistic level model also is based on second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density.

  1. A parabolic-hyperbolic system modelling a moving cell

    Directory of Open Access Journals (Sweden)

    Fabiana Cardetti

    2009-08-01

    Full Text Available In this article, we study the existence and uniqueness of local solutions for a moving boundary problem governed by a coupled parabolic-hyperbolic system. The results can be applied to cell movement, extending a result obtained by Choi, Groulx, and Lui in 2005.

  2. Modelling and optimization of reforming systems for use in PEM fuel cell systems

    International Nuclear Information System (INIS)

    Berry, M.; Korsgaard, A.R.; Nielsen, M.P.

    2004-01-01

    Three different reforming methods for the conversion of natural gas to hydrogen are studied and compared: Steam Reforming (SR), Auto-thermal Reforming (ATR), and Catalytic Partial Oxidation (CPOX). Thermodynamic and kinetic models are developed for the reforming reactors as well as the subsequent reactors needed for CO removal to make the synthesis gas suitable for use in a PEM fuel cell. The systems are optimized to minimize the total volume, and must supply adequate hydrogen to a fuel cell with a 100kW load. The resultant system efficiencies are calculated. The CPOX system is the smallest and exhibits a comparable efficiency to the SR system. The SR system had the best relation between efficiency and volume increase. Optimal temperature profiles within each reactor were found. It was shown that temperature control can significantly reduce reactor volume and increase conversion capabilities. (author)

  3. Systems Modelling and the Development of Coherent Understanding of Cell Biology

    Science.gov (United States)

    Verhoeff, Roald P.; Waarlo, Arend Jan; Boersma, Kerst Th.

    2008-01-01

    This article reports on educational design research concerning a learning and teaching strategy for cell biology in upper-secondary education introducing "systems modelling" as a key competence. The strategy consists of four modelling phases in which students subsequently develop models of free-living cells, a general two-dimensional model of…

  4. Gas composition modeling in a reformed Methanol Fuel Cell system using adaptive Neuro-Fuzzy Inference Systems

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2013-01-01

    This work presents a method for modeling the gas composition in a Reformed Methanol Fuel Cell system. The method is based on Adaptive Neuro-Fuzzy-Inference-Systems which are trained on experimental data. The developed models are of the H2, CO2, CO and CH3OH mass flows of the reformed gas. The ANFIS......, or fuel cell diagnostics systems....

  5. Modeling and optimization of the air system in polymer exchange membrane fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Cheng; Ouyang, Minggao [State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084 (China); Yi, Baolian [Dalian Institute of Chemical Physics, CAS, Dalian 116023 (China)

    2006-06-01

    Stack and air system are the two most important components in the fuel cell system (FCS). It is meaningful to study their properties and the trade-off between them. In this paper, a modified one-dimensional steady-state analytical fuel cell model is used. The logarithmic mean of the inlet and the outlet oxygen partial pressure is adopted to avoid underestimating the effect of air stoichiometry. And the pressure drop model in the grid-distributed flow field is included in the stack analysis. Combined with the coordinate change preprocessing and analog technique, neural network is used to treat the MAP of compressor and turbine in the air system. Three kinds of air system topologies, the pure screw compressor, serial booster and exhaust expander are analyzed in this article. A real-code genetic algorithm is programmed to obtain the global optimum air stoichiometric ratio and the cathode outlet pressure. It is shown that the serial booster and expander with the help of exhaust recycling, can improve more than 3% in the FCS efficiency comparing to the pure screw compressor. As the net power increases, the optimum cathode outlet pressure keeps rising and the air stoichiometry takes on the concave trajectory. The working zone of the proportional valve is also discussed. This presented work is helpful to the design of the air system in fuel cell system. The steady-state optimum can also be used in the dynamic control. (author)

  6. Modeling and optimization of the air system in polymer exchange membrane fuel cell systems

    Science.gov (United States)

    Bao, Cheng; Ouyang, Minggao; Yi, Baolian

    Stack and air system are the two most important components in the fuel cell system (FCS). It is meaningful to study their properties and the trade-off between them. In this paper, a modified one-dimensional steady-state analytical fuel cell model is used. The logarithmic mean of the inlet and the outlet oxygen partial pressure is adopted to avoid underestimating the effect of air stoichiometry. And the pressure drop model in the grid-distributed flow field is included in the stack analysis. Combined with the coordinate change preprocessing and analog technique, neural network is used to treat the MAP of compressor and turbine in the air system. Three kinds of air system topologies, the pure screw compressor, serial booster and exhaust expander are analyzed in this article. A real-code genetic algorithm is programmed to obtain the global optimum air stoichiometric ratio and the cathode outlet pressure. It is shown that the serial booster and expander with the help of exhaust recycling, can improve more than 3% in the FCS efficiency comparing to the pure screw compressor. As the net power increases, the optimum cathode outlet pressure keeps rising and the air stoichiometry takes on the concave trajectory. The working zone of the proportional valve is also discussed. This presented work is helpful to the design of the air system in fuel cell system. The steady-state optimum can also be used in the dynamic control.

  7. Nonlinear Model Predictive Control for Solid Oxide Fuel Cell System Based On Wiener Model

    OpenAIRE

    T. H. Lee; J. H. Park; S. M. Lee; S. C. Lee

    2010-01-01

    In this paper, we consider Wiener nonlinear model for solid oxide fuel cell (SOFC). The Wiener model of the SOFC consists of a linear dynamic block and a static output non-linearity followed by the block, in which linear part is approximated by state-space model and the nonlinear part is identified by a polynomial form. To control the SOFC system, we have to consider various view points such as operating conditions, another constraint conditions, change of load current and so on. A change of ...

  8. GEM System: automatic prototyping of cell-wide metabolic pathway models from genomes

    Directory of Open Access Journals (Sweden)

    Nakayama Yoichi

    2006-03-01

    Full Text Available Abstract Background Successful realization of a "systems biology" approach to analyzing cells is a grand challenge for our understanding of life. However, current modeling approaches to cell simulation are labor-intensive, manual affairs, and therefore constitute a major bottleneck in the evolution of computational cell biology. Results We developed the Genome-based Modeling (GEM System for the purpose of automatically prototyping simulation models of cell-wide metabolic pathways from genome sequences and other public biological information. Models generated by the GEM System include an entire Escherichia coli metabolism model comprising 968 reactions of 1195 metabolites, achieving 100% coverage when compared with the KEGG database, 92.38% with the EcoCyc database, and 95.06% with iJR904 genome-scale model. Conclusion The GEM System prototypes qualitative models to reduce the labor-intensive tasks required for systems biology research. Models of over 90 bacterial genomes are available at our web site.

  9. cellPACK: a virtual mesoscope to model and visualize structural systems biology.

    Science.gov (United States)

    Johnson, Graham T; Autin, Ludovic; Al-Alusi, Mostafa; Goodsell, David S; Sanner, Michel F; Olson, Arthur J

    2015-01-01

    cellPACK assembles computational models of the biological mesoscale, an intermediate scale (10-100 nm) between molecular and cellular biology scales. cellPACK's modular architecture unites existing and novel packing algorithms to generate, visualize and analyze comprehensive three-dimensional models of complex biological environments that integrate data from multiple experimental systems biology and structural biology sources. cellPACK is available as open-source code, with tools for validation of models and with 'recipes' and models for five biological systems: blood plasma, cytoplasm, synaptic vesicles, HIV and a mycoplasma cell. We have applied cellPACK to model distributions of HIV envelope protein to test several hypotheses for consistency with experimental observations. Biologists, educators and outreach specialists can interact with cellPACK models, develop new recipes and perform packing experiments through scripting and graphical user interfaces at http://cellPACK.org/.

  10. Hardware-in-the-loop vehicle system including dynamic fuel cell model

    Energy Technology Data Exchange (ETDEWEB)

    Lemes, Z.; Lenhart, T.; Braun, M.; Maencher, H. [MAGNUM Automatisierungstechnik GmbH, Darmstadt (Germany)

    2005-07-01

    In order to reduce costs and accelerate the development of fuel cells and systems the usage of hardware-in-the-loop (HIL) testing and dynamic modelling opens new possibilities. The dynamic model of a proton exchange membrane fuel cell (PEMFC) together with a vehicle model is used to carry out a comprehensive system investigation, which allows designing and optimising the behaviour of the components and the entire fuel cell system. The set-up of a HIL system enables real time interaction between the selected hardware and the model. (orig.)

  11. Model study of radiation effects on the gastrointestinal cell system

    International Nuclear Information System (INIS)

    Kicherer, G.

    1983-03-01

    Since it is now possible to calculate the radiation fields used for medicinal purposes by means of radiation transport programs it was started to determine with mathematical models of radioeffects not only the physical effects or irradiation, but also the resulting biological radioresponses. This supplementary biologic information is not only of large general importance, but particularly valuable for the medicinal application of the biologically highly effective neutron radiation. With support by the Institute for Medicinal Radiophysics and Radiobiology of Essen University Hospital, and of two biomathematical working groups of Ulm University and Cologne University Hospital, who are experienced in the field of establishing mathematical models of the hematogenic cellular system, we developed out of experimental fundamental findings a cellkinetic, kybernetic model of the intestinal mucosa, which is highly sensitive to radiation. With this newly established model we succeeded for the first time in simulating comprehensively and quantitatively the time-dependent acute radioresponse of such a radiosensitive cellular system. For the first time we successfully used the computer simulation languages DARE-P and GASP, which are principally employed for solving problems in automatic control technology, and set up a radioresponse model. (orig.) [de

  12. Modeling and analysis of cell membrane systems with probabilistic model checking

    Science.gov (United States)

    2011-01-01

    Background Recently there has been a growing interest in the application of Probabilistic Model Checking (PMC) for the formal specification of biological systems. PMC is able to exhaustively explore all states of a stochastic model and can provide valuable insight into its behavior which are more difficult to see using only traditional methods for system analysis such as deterministic and stochastic simulation. In this work we propose a stochastic modeling for the description and analysis of sodium-potassium exchange pump. The sodium-potassium pump is a membrane transport system presents in all animal cell and capable of moving sodium and potassium ions against their concentration gradient. Results We present a quantitative formal specification of the pump mechanism in the PRISM language, taking into consideration a discrete chemistry approach and the Law of Mass Action aspects. We also present an analysis of the system using quantitative properties in order to verify the pump reversibility and understand the pump behavior using trend labels for the transition rates of the pump reactions. Conclusions Probabilistic model checking can be used along with other well established approaches such as simulation and differential equations to better understand pump behavior. Using PMC we can determine if specific events happen such as the potassium outside the cell ends in all model traces. We can also have a more detailed perspective on its behavior such as determining its reversibility and why its normal operation becomes slow over time. This knowledge can be used to direct experimental research and make it more efficient, leading to faster and more accurate scientific discoveries. PMID:22369714

  13. Dynamic Modeling of a Reformed Methanol Fuel Cell System using Empirical Data and Adaptive Neuro-Fuzzy Inference System Models

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2013-01-01

    In this work, a dynamic MATLAB Simulink model of a H3-350 Reformed Methanol Fuel Cell (RMFC) stand-alone battery charger produced by Serenergy is developed on the basis of theoretical and empirical methods. The advantage of RMFC systems is that they use liquid methanol as a fuel instead of gaseous...... of the reforming process are implemented. Models of the cooling flow of the blowers for the fuel cell and the burner which supplies process heat for the reformer are made. The two blowers have a common exhaust, which means that the two blowers influence each other’s output. The models take this into account using...... an empirical approach. Fin efficiency models for the cooling effect of the air are also developed using empirical methods. A fuel cell model is also implemented based on a standard model which is adapted to fit the measured performance of the H3-350 module. All the individual parts of the model are verified...

  14. Dynamic Modeling of a Reformed Methanol Fuel Cell System using Empirical Data and Adaptive Neuro-Fuzzy Inference System Models

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2014-01-01

    In this work, a dynamic MATLAB Simulink model of a H3-350 Reformed Methanol Fuel Cell (RMFC) stand-alone battery charger produced by Serenergy is developed on the basis of theoretical and empirical methods. The advantage of RMFC systems is that they use liquid methanol as a fuel instead of gaseous...... of the reforming process are implemented. Models of the cooling flow of the blowers for the fuel cell and the burner which supplies process heat for the reformer are made. The two blowers have a common exhaust, which means that the two blowers influence each other’s output. The models take this into account using...... an empirical approach. Fin efficiency models for the cooling effect of the air are also developed using empirical methods. A fuel cell model is also implemented based on a standard model which is adapted to fit the measured performance of the H3-350 module. All the individual parts of the model are verified...

  15. Modeling and control of the output current of a Reformed Methanol Fuel Cell system

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Pasupathi, Sivakumar

    2015-01-01

    In this work, a dynamic Matlab SIMULINK model of the relationship between the fuel cell current set point of a Reformed Methanol Fuel Cell system and the output current of the system is developed. The model contains an estimated fuel cell model, based on a polarization curve and assumed first order...... dynamics, as well as a battery model based on an equivalent circuit model and a balance of plant power consumption model. The models are tuned with experimental data and verified using a verification data set. The model is used to develop an output current controller which can control the charge current...... of the battery. The controller is a PI controller with feedforward and anti-windup. The performance of the controller is tested and verified on the physical system....

  16. A data integration approach for cell cycle analysis oriented to model simulation in systems biology

    Directory of Open Access Journals (Sweden)

    Mosca Ettore

    2007-08-01

    Full Text Available Abstract Background The cell cycle is one of the biological processes most frequently investigated in systems biology studies and it involves the knowledge of a large number of genes and networks of protein interactions. A deep knowledge of the molecular aspect of this biological process can contribute to making cancer research more accurate and innovative. In this context the mathematical modelling of the cell cycle has a relevant role to quantify the behaviour of each component of the systems. The mathematical modelling of a biological process such as the cell cycle allows a systemic description that helps to highlight some features such as emergent properties which could be hidden when the analysis is performed only from a reductionism point of view. Moreover, in modelling complex systems, a complete annotation of all the components is equally important to understand the interaction mechanism inside the network: for this reason data integration of the model components has high relevance in systems biology studies. Description In this work, we present a resource, the Cell Cycle Database, intended to support systems biology analysis on the Cell Cycle process, based on two organisms, yeast and mammalian. The database integrates information about genes and proteins involved in the cell cycle process, stores complete models of the interaction networks and allows the mathematical simulation over time of the quantitative behaviour of each component. To accomplish this task, we developed, a web interface for browsing information related to cell cycle genes, proteins and mathematical models. In this framework, we have implemented a pipeline which allows users to deal with the mathematical part of the models, in order to solve, using different variables, the ordinary differential equation systems that describe the biological process. Conclusion This integrated system is freely available in order to support systems biology research on the cell cycle and

  17. System model development for a methanol reformed 5 kW high temperature PEM fuel cell system

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2015-01-01

    This work investigates the system performance when reforming methanol in an oil heated reformer system for a 5 kW fuel cell system. A dynamic model of the system is created and evaluated. The system is divided into 4 separate components. These components are the fuel cell, reformer, burner...... and evaporator, which are connected by two separate oil circuits, one with a burner and reformer and one with a fuel cell and evaporator. Experiments were made on the reformer and measured oil and bed temperatures are presented in multiple working points. The system is examined at loads from 0 to 5000 W electric...

  18. Modeling and control of a small solar fuel cell hybrid energy system

    Institute of Scientific and Technical Information of China (English)

    LI Wei; ZHU Xin-jian; CAO Guang-yi

    2007-01-01

    This paper describes a solar photovoltaic fuel cell (PVEC) hybrid generation system consisting of a photovoltaic (PV) generator, a proton exchange membrane fuel cell (PEMFC), an electrolyser, a supercapacitor, a storage gas tank and power conditioning unit (PCU). The load is supplied from the PV generator with a fuel cell working in parallel. Excess PV energy when available is converted to hydrogen using an electrolyser for later use in the fuel cell. The individual mathematical model for each component is presented. Control strategy for the system is described. MATLAB/Simulink is used for the simulation of this highly nonlinear hybrid energy system. The simulation results are shown in the paper.

  19. Thermal modeling and temperature control of a PEM fuel cell system for forklift applications

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh; Kær, Søren Knudsen

    2014-01-01

    Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature....... A combination of high temperature and reduced humidity increases the degradation rate. Stack thermal management and control are, thus, crucial issues in PEM fuel cell systems especially in automotive applications such as forklifts. In this paper we present a control–oriented dynamic model of a liquid–cooled PEM...... fuel cell system for studying temperature variations over fast load changes. A temperature dependent cell polarization and hydration model integrated with the compressor, humidifier and cooling system are simulated in dynamic condition. A feedback PID control was implemented for stack cooling...

  20. Fuel Cell Power Model Version 2: Startup Guide, System Designs, and Case Studies. Modeling Electricity, Heat, and Hydrogen Generation from Fuel Cell-Based Distributed Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Steward, D.; Penev, M.; Saur, G.; Becker, W.; Zuboy, J.

    2013-06-01

    This guide helps users get started with the U.S. Department of Energy/National Renewable Energy Laboratory Fuel Cell Power (FCPower) Model Version 2, which is a Microsoft Excel workbook that analyzes the technical and economic aspects of high-temperature fuel cell-based distributed energy systems with the aim of providing consistent, transparent, comparable results. This type of energy system would provide onsite-generated heat and electricity to large end users such as hospitals and office complexes. The hydrogen produced could be used for fueling vehicles or stored for later conversion to electricity.

  1. Mathematical model of reproductive death of irradiated eukaryotic cells, which considers saturation of DNA reparation system

    International Nuclear Information System (INIS)

    Knyigavko, V.G.; Ponomarenko, N.S.; Meshcheryakova, O.P.; Protasenya, S.Yu.

    2009-01-01

    A mathematical model of the processes determining reproductive death of the exposed cells was built. The model takes into account the phenomenon of saturation of the system of DNA radiation lesion reparation and structural functional peculiarities of chromatin structure in eukaryotes. The problem of assessment of the model parameters using experimental data was discussed.

  2. Modeling of a HTPEM fuel cell using Adaptive Neuro-Fuzzy Inference Systems

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Sahlin, Simon Lennart

    2015-01-01

    In this work an Adaptive Neuro-Fuzzy Inference System (ANFIS) model of the voltage of a fuel cell is developed. The inputs of this model are the fuel cell temperature, current density and the carbon monoxide concentration of the anode supply gas. First an identification experiment which spans...... the expected operating range of the fuel cell is performed in a test station. The data from this experiment is then used to train ANFIS models with 2, 3, 4 and 5 membership functions. The performance of these models is then compared and it is found that using 3 membership functions provides the best compromise...

  3. Modelling and simulation of a PEM fuel cell power system with a fuzzy logic controller

    International Nuclear Information System (INIS)

    Al-Dabbagh, A.W.; Lu, L.; Mazza, A.

    2009-01-01

    Fuel cell power systems are emerging as promising means of electrical power generation on account of the associated clean electricity generation process, as well as their suitability for use in a wide range of applications. During the design stage, the development of a computer model for simulating the behaviour of a system under development can facilitate the experimentation and testing of that system's performance. Since the electrical power output of a fuel cell stack is seldom at a suitable fixed voltage, conditioning circuits and their associated controllers must be incorporated in the design of the fuel cell power system. This paper presents a MATLAB/Simulink model that simulates the behaviour of a Proton Exchange Membrane (PEM) fuel cell, conditioning circuits and their controllers. The computer modelling of the PEMFC was based on adopted mathematical models that describe the fuel cell's operational voltage, while accounting for the irreversibilities associated with the fuel cell stack. The conditioning circuits that are included in the Simulink model are a DC-DC converter and DC-AC inverter circuits. These circuits are the commonly utilized power electronics circuits for regulating and conditioning the output voltage from a fuel cell stack. The modelling of the circuits is based on relationships that govern the output voltage behaviour with respect to their input voltages, switching duty cycle and efficiency. In addition, this paper describes a Fuzzy Logic Controller (FLC) design that is aimed at regulating the conditioning circuits to provide and maintain suitable electrical power for a wide range of applications. (author)

  4. Description and modelling of the solar-hydrogen-biogas-fuel cell system in GlashusEtt

    Science.gov (United States)

    Hedström, L.; Wallmark, C.; Alvfors, P.; Rissanen, M.; Stridh, B.; Ekman, J.

    The need to reduce pollutant emissions and utilise the world's available energy resources more efficiently has led to increased attention towards e.g. fuel cells, but also to other alternative energy solutions. In order to further understand and evaluate the prerequisites for sustainable and energy-saving systems, ABB and Fortum have equipped an environmental information centre, located in Hammarby Sjöstad, Stockholm, Sweden, with an alternative energy system. The system is being used to demonstrate and evaluate how a system based on fuel cells and solar cells can function as a complement to existing electricity and heat production. The stationary energy system is situated on the top level of a three-floor glass building and is open to the public. The alternative energy system consists of a fuel cell system, a photovoltaic (PV) cell array, an electrolyser, hydrogen storage tanks, a biogas burner, dc/ac inverters, heat exchangers and an accumulator tank. The fuel cell system includes a reformer and a polymer electrolyte fuel cell (PEFC) with a maximum rated electrical output of 4 kW el and a maximum thermal output of 6.5 kW th. The fuel cell stack can be operated with reformed biogas, or directly using hydrogen produced by the electrolyser. The cell stack in the electrolyser consists of proton exchange membrane (PEM) cells. To evaluate different automatic control strategies for the system, a simplified dynamic model has been developed in MATLAB Simulink. The model based on measurement data taken from the actual system. The evaluation is based on demand curves, investment costs, electricity prices and irradiation. Evaluation criteria included in the model are electrical and total efficiencies as well as economic parameters.

  5. Models for solid oxide fuel cell systems exploitation of models hierarchy for industrial design of control and diagnosis strategies

    CERN Document Server

    Marra, Dario; Polverino, Pierpaolo; Sorrentino, Marco

    2016-01-01

    This book presents methodologies for optimal design of control and diagnosis strategies for Solid Oxide Fuel Cell systems. A key feature of the methodologies presented is the exploitation of modelling tools that balance accuracy and computational burden.

  6. Unleashing the potential of the root hair cell as a single plant cell type model in root systems biology

    Directory of Open Access Journals (Sweden)

    Zhenzhen eQiao

    2013-11-01

    Full Text Available Plant root is an organ composed of multiple cell types with different functions. This multicellular complexity limits our understanding of root biology because –omics studies performed at the level of the entire root reflect the average responses of all cells composing the organ. To overcome this difficulty and allow a more comprehensive understanding of root cell biology, an approach is needed that would focus on one single cell type in the plant root. Because of its biological functions (i.e. uptake of water and various nutrients; primary site of infection by nitrogen-fixing bacteria in legumes, the root hair cell is an attractive single cell model to study root cell response to various stresses and treatments. To fully study their biology, we have recently optimized procedures in obtaining root hair cell samples. We culture the plants using an ultrasound aeroponic system maximizing root hair cell density on the entire root systems and allowing the homogeneous treatment of the root system. We then isolate the root hair cells in liquid nitrogen. Isolated root hair yields could be up to 800 to 1000 mg of plant cells from 60 root systems. Using soybean as a model, the purity of the root hair was assessed by comparing the expression level of genes previously identified as soybean root hair specific between preparations of isolated root hair cells and stripped roots, roots devoid in root hairs. Enlarging our tests to include other plant species, our results support the isolation of large quantities of highly purified root hair cells which is compatible with a systems biology approach.

  7. A systems model for immune cell interactions unravels the mechanism of inflammation in human skin.

    Science.gov (United States)

    Valeyev, Najl V; Hundhausen, Christian; Umezawa, Yoshinori; Kotov, Nikolay V; Williams, Gareth; Clop, Alex; Ainali, Crysanthi; Ouzounis, Christos; Tsoka, Sophia; Nestle, Frank O

    2010-12-02

    Inflammation is characterized by altered cytokine levels produced by cell populations in a highly interdependent manner. To elucidate the mechanism of an inflammatory reaction, we have developed a mathematical model for immune cell interactions via the specific, dose-dependent cytokine production rates of cell populations. The model describes the criteria required for normal and pathological immune system responses and suggests that alterations in the cytokine production rates can lead to various stable levels which manifest themselves in different disease phenotypes. The model predicts that pairs of interacting immune cell populations can maintain homeostatic and elevated extracellular cytokine concentration levels, enabling them to operate as an immune system switch. The concept described here is developed in the context of psoriasis, an immune-mediated disease, but it can also offer mechanistic insights into other inflammatory pathologies as it explains how interactions between immune cell populations can lead to disease phenotypes.

  8. A systems model for immune cell interactions unravels the mechanism of inflammation in human skin.

    Directory of Open Access Journals (Sweden)

    Najl V Valeyev

    2010-12-01

    Full Text Available Inflammation is characterized by altered cytokine levels produced by cell populations in a highly interdependent manner. To elucidate the mechanism of an inflammatory reaction, we have developed a mathematical model for immune cell interactions via the specific, dose-dependent cytokine production rates of cell populations. The model describes the criteria required for normal and pathological immune system responses and suggests that alterations in the cytokine production rates can lead to various stable levels which manifest themselves in different disease phenotypes. The model predicts that pairs of interacting immune cell populations can maintain homeostatic and elevated extracellular cytokine concentration levels, enabling them to operate as an immune system switch. The concept described here is developed in the context of psoriasis, an immune-mediated disease, but it can also offer mechanistic insights into other inflammatory pathologies as it explains how interactions between immune cell populations can lead to disease phenotypes.

  9. Fuel cell/back-up battery hybrid energy conversion systems: Dynamic modeling and harmonic considerations

    International Nuclear Information System (INIS)

    Fathabadi, Hassan

    2015-01-01

    Highlights: • Novel technique to completely eliminate the harmful harmonics of fuel cell system. • Presenting a novel high accurate detailed electrochemical dynamic model of fuel cells. • Back-up battery system to compensate the slow dynamic response of fuel cell system. • Exact analysis of real electrochemical reactions occurring inside fuel cells. - Abstract: In this study, a novel dynamic model of fuel cells is presented. High accurate static and dynamic responses of the proposed model are experimentally validated by comparing simulated results with real experimental data. The obtained model together with theoretical results shows that a fuel cell or a fuel cell stack has very slow dynamic response, so that, it cannot adapt itself to the fast variations in load demand. It is shown that for adapting well a fuel cell stack to the load demand, the stack should be equipped with a proposed back-up battery system which compensates the slow dynamic response of the stack by providing a bidirectional path to transmit/absorb the extra instant power. It is proved that the conventional switching waveforms used in the converters of the stacks and back-up systems produce an enormous amount of harmful harmonics. Then, a novel technique is proposed to completely eliminate main harmful harmonics. It is worthwhile to note that all the other techniques only reduce the harmful harmonics. Simulated results verify that the back-up battery system together with applying the proposed technique provide a fast dynamic response for the fuel cell/back-up battery system, and also completely eliminate the main harmful harmonics

  10. Model predictive control of fuel cell micro cogeneration systems

    NARCIS (Netherlands)

    Houwing, M.; Negenborn, R.R.; Ilic, M.D.; De Schutter, B.

    2009-01-01

    With the increasing application of distributed energy resources and information technologies in the electricity infrastructure, innovative possibilities for incorporating the demand side more actively in power system operation are enabled. At the residential level energy costs could be reduced with

  11. Modeling and operation optimization of a proton exchange membrane fuel cell system for maximum efficiency

    International Nuclear Information System (INIS)

    Han, In-Su; Park, Sang-Kyun; Chung, Chang-Bock

    2016-01-01

    Highlights: • A proton exchange membrane fuel cell system is operationally optimized. • A constrained optimization problem is formulated to maximize fuel cell efficiency. • Empirical and semi-empirical models for most system components are developed. • Sensitivity analysis is performed to elucidate the effects of major operating variables. • The optimization results are verified by comparison with actual operation data. - Abstract: This paper presents an operation optimization method and demonstrates its application to a proton exchange membrane fuel cell system. A constrained optimization problem was formulated to maximize the efficiency of a fuel cell system by incorporating practical models derived from actual operations of the system. Empirical and semi-empirical models for most of the system components were developed based on artificial neural networks and semi-empirical equations. Prior to system optimizations, the developed models were validated by comparing simulation results with the measured ones. Moreover, sensitivity analyses were performed to elucidate the effects of major operating variables on the system efficiency under practical operating constraints. Then, the optimal operating conditions were sought at various system power loads. The optimization results revealed that the efficiency gaps between the worst and best operation conditions of the system could reach 1.2–5.5% depending on the power output range. To verify the optimization results, the optimal operating conditions were applied to the fuel cell system, and the measured results were compared with the expected optimal values. The discrepancies between the measured and expected values were found to be trivial, indicating that the proposed operation optimization method was quite successful for a substantial increase in the efficiency of the fuel cell system.

  12. Development of a model system to analyze chondrogenic differentiation of mesenchymal stem cells

    Science.gov (United States)

    Ruedel, Anke; Hofmeister, Simone; Bosserhoff, Anja-Katrin

    2013-01-01

    High-density cell culture is widely used for the analysis of cartilage development of human mesenchymal stem cells (HMSCs) in vitro. Several cell culture systems, as micromass, pellet culture and alginate culture, are applied by groups in the field to induce chondrogenic differentiation of HMSCs. A draw back of all model systems is the high amount of cells necessary for the experiments. Further, handling of large experimental approaches is difficult due to culturing e.g. in 15 ml tubes. Therefore, we aimed to develop a new model system based on “hanging drop” cultures using 10 to 100 fold less cells. Here, we demonstrate that differentiation of chondrogenic cells was induced as previously shown in other model systems. Real time RT-PCR analysis demonstrated that Collagen type II and MIA/CD-RAP were upregulated during culturing whereas for induction of hypertrophic markers like Collagen type X and AP-2 epsilon treatment with TGF beta was needed. To further test the system, siRNA against Sox9 was used and effects on chondrogenic gene expression were evaluated. In summary, the hanging drop culture system was determined to be a promising tool for in vitro chondrogenic studies. PMID:24294400

  13. Three-dimensional hydrogel cell culture systems for modeling neural tissue

    Science.gov (United States)

    Frampton, John

    Two-dimensional (2-D) neural cell culture systems have served as physiological models for understanding the cellular and molecular events that underlie responses to physical and chemical stimuli, control sensory and motor function, and lead to the development of neurological diseases. However, the development of three-dimensional (3-D) cell culture systems will be essential for the advancement of experimental research in a variety of fields including tissue engineering, chemical transport and delivery, cell growth, and cell-cell communication. In 3-D cell culture, cells are provided with an environment similar to tissue, in which they are surrounded on all sides by other cells, structural molecules and adhesion ligands. Cells grown in 3-D culture systems display morphologies and functions more similar to those observed in vivo, and can be cultured in such a way as to recapitulate the structural organization and biological properties of tissue. This thesis describes a hydrogel-based culture system, capable of supporting the growth and function of several neural cell types in 3-D. Alginate hydrogels were characterized in terms of their biomechanical and biochemical properties and were functionalized by covalent attachment of whole proteins and peptide epitopes. Methods were developed for rapid cross-linking of alginate hydrogels, thus permitting the incorporation of cells into 3-D scaffolds without adversely affecting cell viability or function. A variety of neural cell types were tested including astrocytes, microglia, and neurons. Cells remained viable and functional for longer than two weeks in culture and displayed process outgrowth in 3-D. Cell constructs were created that varied in cell density, type and organization, providing experimental flexibility for studying cell interactions and behavior. In one set of experiments, 3-D glial-endothelial cell co-cultures were used to model blood-brain barrier (BBB) structure and function. This co-culture system was

  14. CALCULUS FROM THE PAST: MULTIPLE DELAY SYSTEMS ARISING IN CANCER CELL MODELLING

    KAUST Repository

    WAKE, G. C.; BYRNE, H. M.

    2013-01-01

    Nonlocal calculus is often overlooked in the mathematics curriculum. In this paper we present an interesting new class of nonlocal problems that arise from modelling the growth and division of cells, especially cancer cells, as they progress through the cell cycle. The cellular biomass is assumed to be unstructured in size or position, and its evolution governed by a time-dependent system of ordinary differential equations with multiple time delays. The system is linear and taken to be autonomous. As a result, it is possible to reduce its solution to that of a nonlinear matrix eigenvalue problem. This method is illustrated by considering case studies, including a model of the cell cycle developed recently by Simms, Bean and Koeber. The paper concludes by explaining how asymptotic expressions for the distribution of cells across the compartments can be determined and used to assess the impact of different chemotherapeutic agents. Copyright © 2013 Australian Mathematical Society.

  15. Molecular model of a type III secretion system needle: Implications for host-cell sensing.

    Science.gov (United States)

    Deane, Janet E; Roversi, Pietro; Cordes, Frank S; Johnson, Steven; Kenjale, Roma; Daniell, Sarah; Booy, Frank; Picking, William D; Picking, Wendy L; Blocker, Ariel J; Lea, Susan M

    2006-08-15

    Type III secretion systems are essential virulence determinants for many Gram-negative bacterial pathogens. The type III secretion system consists of cytoplasmic, transmembrane, and extracellular domains. The extracellular domain is a hollow needle protruding above the bacterial surface and is held within a basal body that traverses both bacterial membranes. Effector proteins are translocated, via this external needle, directly into host cells, where they subvert normal cell functions to aid infection. Physical contact with host cells initiates secretion and leads to formation of a pore, thought to be contiguous with the needle channel, in the host-cell membrane. Here, we report the crystal structure of the Shigella flexneri needle subunit MxiH and a complete model for the needle assembly built into our three-dimensional EM reconstruction. The model, combined with mutagenesis data, reveals that signaling of host-cell contact is relayed through the needle via intersubunit contacts and suggests a mode of binding for a tip complex.

  16. Dynamic modeling, experimental evaluation, optimal design and control of integrated fuel cell system and hybrid energy systems for building demands

    Science.gov (United States)

    Nguyen, Gia Luong Huu

    Fuel cells can produce electricity with high efficiency, low pollutants, and low noise. With the advent of fuel cell technologies, fuel cell systems have since been demonstrated as reliable power generators with power outputs from a few watts to a few megawatts. With proper equipment, fuel cell systems can produce heating and cooling, thus increased its overall efficiency. To increase the acceptance from electrical utilities and building owners, fuel cell systems must operate more dynamically and integrate well with renewable energy resources. This research studies the dynamic performance of fuel cells and the integration of fuel cells with other equipment in three levels: (i) the fuel cell stack operating on hydrogen and reformate gases, (ii) the fuel cell system consisting of a fuel reformer, a fuel cell stack, and a heat recovery unit, and (iii) the hybrid energy system consisting of photovoltaic panels, fuel cell system, and energy storage. In the first part, this research studied the steady-state and dynamic performance of a high temperature PEM fuel cell stack. Collaborators at Aalborg University (Aalborg, Denmark) conducted experiments on a high temperature PEM fuel cell short stack at steady-state and transients. Along with the experimental activities, this research developed a first-principles dynamic model of a fuel cell stack. The dynamic model developed in this research was compared to the experimental results when operating on different reformate concentrations. Finally, the dynamic performance of the fuel cell stack for a rapid increase and rapid decrease in power was evaluated. The dynamic model well predicted the performance of the well-performing cells in the experimental fuel cell stack. The second part of the research studied the dynamic response of a high temperature PEM fuel cell system consisting of a fuel reformer, a fuel cell stack, and a heat recovery unit with high thermal integration. After verifying the model performance with the

  17. Dynamic Thermal Model And Control Of A Pem Fuel Cell System

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh

    2013-01-01

    the fuel cell system. A PID temperature control is implemented to study the effect of stack temperature on settling times of other variables such as stack voltage, air flow rate, oxygen excess ratio and net power of the stack. The model allows an assessment of the effect of operating parameters (stack...... power output, cooling water flow rate, air flow rate, and environmental temperature) and parameter interactions on the system thermal performance. The model represents a useful tool to determine the operating temperatures of the various components of the thermal system, and thus to fully assess......A lumped parameter dynamic model is developed for predicting the stack performance, temperatures of the exit reactant gases and coolant liquid outlet in a proton-exchange membrane fuel cell (PEMFC) system. The air compressor, humidifier and cooling heat exchanger models are integrated to study...

  18. A methodology for thermo-economic modeling and optimization of solid oxide fuel cell systems

    International Nuclear Information System (INIS)

    Palazzi, Francesca; Autissier, Nordahl; Marechal, Francois M.A.; Favrat, Daniel

    2007-01-01

    In the context of stationary power generation, fuel cell-based systems are being foreseen as a valuable alternative to thermodynamic cycle-based power plants, especially in small scale applications. As the technology is not yet established, many aspects of fuel cell development are currently investigated worldwide. Part of the research focuses on integrating the fuel cell in a system that is both efficient and economically attractive. To address this problem, we present in this paper a thermo-economic optimization method that systematically generates the most attractive configurations of an integrated system. In the developed methodology, the energy flows are computed using conventional process simulation software. The system is integrated using the pinch based methods that rely on optimization techniques. This defines the minimum of energy required and sets the basis to design the ideal heat exchanger network. A thermo-economic method is then used to compute the integrated system performances, sizes and costs. This allows performing the optimization of the system with regard to two objectives: minimize the specific cost and maximize the efficiency. A solid oxide fuel cell (SOFC) system of 50 kW integrating a planar SOFC is modeled and optimized leading to designs with efficiencies ranging from 34% to 44%. The multi-objective optimization strategy identifies interesting system configurations and their performance for the developed SOFC system model. The methods proves to be an attractive tool to be used both as an advanced analysis tool and as support to decision makers when designing new systems

  19. Modelling and Optimization of Reforming Systems for use in PEM Fuel Cell

    DEFF Research Database (Denmark)

    Berry, Melissa; Korsgaard, Anders Risum; Nielsen, Mads Pagh

    2004-01-01

    Three different reforming methods for the conversion of natural gas to hydrogen are studied and compared: Steam Reforming (SR), Auto-thermal Reforming (ATR), and Catalytic Partial Oxidation (CPOX). Thermodynamic and kinetic models are developed for the reforming reactors as well as the subsequent...... reactors needed for CO removal to make the synthesis gas suitable for use in a PEM fuel cell. The systems are optimized to minimize the total volume, and must supply adequate hydrogen to a fuel cell with a 100kW load. The resultant system efficiencies are calculated. The CPOX system is the smallest...

  20. Modeling and control of hybrid wind/photovoltaic/fuel cell distributed generation systems

    Science.gov (United States)

    Wang, Caisheng

    Due to ever increasing energy consumption, rising public awareness of environmental protection, and steady progress in power deregulation, alternative (i.e., renewable and fuel cell based) distributed generation (DG) systems have attracted increased interest. Wind and photovoltaic (PV) power generation are two of the most promising renewable energy technologies. Fuel cell (FC) systems also show great potential in DG applications of the future due to their fast technology development and many merits they have, such as high efficiency, zero or low emission (of pollutant gases) and flexible modular structure. The modeling and control of a hybrid wind/PV/FC DG system is addressed in this dissertation. Different energy sources in the system are integrated through an AC bus. Dynamic models for the main system components, namely, wind energy conversion system (WECS), PV energy conversion system (PVECS), fuel cell, electrolyzer, power electronic interfacing circuits, battery, hydrogen storage tank, gas compressor and gas pressure regulator, are developed. Two types of fuel cells have been modeled in this dissertation: proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Power control of a grid-connected FC system as well as load mitigation control of a stand-alone FC system are investigated. The pitch angle control for WECS, the maximum power point tracking (MPPT) control for PVECS, and the control for electrolyzer and power electronic devices, are also addressed in the dissertation. Based on the dynamic component models, a simulation model for the proposed hybrid energy system has been developed using MATLAB/Simulink. The overall power management strategy for coordinating the power flows among the different energy sources is presented in the dissertation. Simulation studies have been carried out to verify the system performance under different scenarios using a practical load profile and real weather data. The results show that the overall power

  1. A quantitative model of the cardiac ventricular cell incorporating the transverse-axial tubular system

    Czech Academy of Sciences Publication Activity Database

    Pásek, Michal; Christé, G.; Šimurda, J.

    2003-01-01

    Roč. 22, č. 3 (2003), s. 355-368 ISSN 0231-5882 R&D Projects: GA ČR GP204/02/D129 Institutional research plan: CEZ:AV0Z2076919 Keywords : cardiac cell * tubular system * quantitative modelling Subject RIV: BO - Biophysics Impact factor: 0.794, year: 2003

  2. Tumour-cell killing by X-rays and immunity quantitated in a mouse model system

    International Nuclear Information System (INIS)

    Porteous, D.D.; Porteous, K.M.; Hughes, M.J.

    1979-01-01

    As part of an investigation of the interaction of X-rays and immune cytotoxicity in tumour control, an experimental mouse model system has been used in which quantitative anti-tumour immunity was raised in prospective recipients of tumour-cell suspensions exposed to varying doses of X-rays in vitro before injection. Findings reported here indicate that, whilst X-rays kill a proportion of cells, induced immunity deals with a fixed number dependent upon the immune status of the host, and that X-rays and anti-tumour immunity do not act synergistically in tumour-cell killing. The tumour used was the ascites sarcoma BP8. (author)

  3. Model system for plant cell biology: GFP imaging in living onion epidermal cells

    Science.gov (United States)

    Scott, A.; Wyatt, S.; Tsou, P. L.; Robertson, D.; Allen, N. S.

    1999-01-01

    The ability to visualize organelle localization and dynamics is very useful in studying cellular physiological events. Until recently, this has been accomplished using a variety of staining methods. However, staining can give inaccurate information due to nonspecific staining, diffusion of the stain or through toxic effects. The ability to target green fluorescent protein (GFP) to various organelles allows for specific labeling of organelles in vivo. The disadvantages of GFP thus far have been the time and money involved in developing stable transformants or maintaining cell cultures for transient expression. In this paper, we present a rapid transient expression system using onion epidermal peels. We have localized GFP to various cellular compartments (including the cell wall) to illustrate the utility of this method and to visualize dynamics of these compartments. The onion epidermis has large, living, transparent cells in a monolayer, making them ideal for visualizing GFP. This method is easy and inexpensive, and it allows for testing of new GFP fusion proteins in a living tissue to determine deleterious effects and the ability to express before stable transformants are attempted.

  4. Modeling of a 5-cell direct methanol fuel cell using adaptive-network-based fuzzy inference systems

    Science.gov (United States)

    Wang, Rongrong; Qi, Liang; Xie, Xiaofeng; Ding, Qingqing; Li, Chunwen; Ma, ChenChi M.

    The methanol concentrations, temperature and current were considered as inputs, the cell voltage was taken as output, and the performance of a direct methanol fuel cell (DMFC) was modeled by adaptive-network-based fuzzy inference systems (ANFIS). The artificial neural network (ANN) and polynomial-based models were selected to be compared with the ANFIS in respect of quality and accuracy. Based on the ANFIS model obtained, the characteristics of the DMFC were studied. The results show that temperature and methanol concentration greatly affect the performance of the DMFC. Within a restricted current range, the methanol concentration does not greatly affect the stack voltage. In order to obtain higher fuel utilization efficiency, the methanol concentrations and temperatures should be adjusted according to the load on the system.

  5. Modeling of a 5-cell direct methanol fuel cell using adaptive-network-based fuzzy inference systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rongrong; Li, Chunwen [Department of Automation, Tsinghua University, Beijing 100084 (China); Qi, Liang; Xie, Xiaofeng [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Ding, Qingqing [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Ma, ChenChi M. [National Tsing Hua University, Hsinchu 300 (China)

    2008-12-01

    The methanol concentrations, temperature and current were considered as inputs, the cell voltage was taken as output, and the performance of a direct methanol fuel cell (DMFC) was modeled by adaptive-network-based fuzzy inference systems (ANFIS). The artificial neural network (ANN) and polynomial-based models were selected to be compared with the ANFIS in respect of quality and accuracy. Based on the ANFIS model obtained, the characteristics of the DMFC were studied. The results show that temperature and methanol concentration greatly affect the performance of the DMFC. Within a restricted current range, the methanol concentration does not greatly affect the stack voltage. In order to obtain higher fuel utilization efficiency, the methanol concentrations and temperatures should be adjusted according to the load on the system. (author)

  6. Advanced Good Cell Culture Practice for human primary, stem cell-derived and organoid models as well as microphysiological systems.

    Science.gov (United States)

    Pamies, David; Bal-Price, Anna; Chesné, Christophe; Coecke, Sandra; Dinnyes, Andras; Eskes, Chantra; Grillari, Regina; Gstraunthaler, Gerhard; Hartung, Thomas; Jennings, Paul; Leist, Marcel; Martin, Ulrich; Passier, Robert; Schwamborn, Jens C; Stacey, Glyn N; Ellinger-Ziegelbauer, Heidrun; Daneshian, Mardas

    2018-04-13

    A major reason for the current reproducibility crisis in the life sciences is the poor implementation of quality control measures and reporting standards. Improvement is needed, especially regarding increasingly complex in vitro methods. Good Cell Culture Practice (GCCP) was an effort from 1996 to 2005 to develop such minimum quality standards also applicable in academia. This paper summarizes recent key developments in in vitro cell culture and addresses the issues resulting for GCCP, e.g. the development of induced pluripotent stem cells (iPSCs) and gene-edited cells. It further deals with human stem-cell-derived models and bioengineering of organo-typic cell cultures, including organoids, organ-on-chip and human-on-chip approaches. Commercial vendors and cell banks have made human primary cells more widely available over the last decade, increasing their use, but also requiring specific guidance as to GCCP. The characterization of cell culture systems including high-content imaging and high-throughput measurement technologies increasingly combined with more complex cell and tissue cultures represent a further challenge for GCCP. The increasing use of gene editing techniques to generate and modify in vitro culture models also requires discussion of its impact on GCCP. International (often varying) legislations and market forces originating from the commercialization of cell and tissue products and technologies are further impacting on the need for the use of GCCP. This report summarizes the recommendations of the second of two workshops, held in Germany in December 2015, aiming map the challenge and organize the process or developing a revised GCCP 2.0.

  7. LPV model for PV cell and fractional control of DC/DC converter for photovoltaic systems

    OpenAIRE

    Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio

    2011-01-01

    This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for V-I characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Reviewed

  8. LPV model for PV cells and fractional control of DC/DC converter for photovoltaic systems

    OpenAIRE

    Martínez González, Rubén; Bolea Monte, Yolanda; Grau Saldes, Antoni; Martínez García, Herminio

    2011-01-01

    This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for VI characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Rev...

  9. HL60 human premyelocitic cell line as a model system for bystander response

    International Nuclear Information System (INIS)

    Dini, V.; Tabocchini, M.A.; Belli, M.; Simone, G.; Di Carlo, B.; Sapora, O.; Superiore di Sanita, Rome

    2007-01-01

    Complete text of publication follows. Objective: to evaluate HL60 human premyelocitic cell line as a model system to study bystander response. Methods: HL60 cell line, isolated from the blood of a patient affected by premyelocitic leukemia, has 45-46 chromosomes with abnormalities mainly on chromosomes 5, 8 and X and can undergo chemical-induced in vitro differentiation. Differentiation gives rise to granulocytes, monocytes or macrophages depending on the drug used. We define as proliferative (AP) cells those in log phase of growth with less than 10 passages from thawing and as differentiated (D) cells those treated with 10 nM TPA (phorbol ester) for 72 hours. Phorbol ester treatment induces differentiation to monocytes and macrophages. Differentiation has been evaluated through the expression of differentiation cluster membrane antigens (CD95, CD9 and CD14). Results: AP cells resulted positive for CD95 and negative for CD9 and CD14, while D cells resulted positive for CD9 and negative for CD95 and CD14. Our data on AP and D cells showed that: (i) the level of intracellular reactive oxygen and nitrogen species (ROS and RNS) is lower in D cells compared to AP cells; (ii) radiation induced DNA damage (single and double strand breaks, SSB and DSB, as measured with the comet assay technique) is lower in D cells than in AP cells. This different radiosensitivity can be related to the higher degree of compactness of nuclear structure in D cells. Radiation induced bystander effect (BE) was analyzed with the medium transfer technique. The medium from irradiated, with 0.5 Gy of γ-rays, AP cells was collected after 0, 2, 4 and 24 hours from irradiation and added to non irradiated log phase cells. The frequency of micronuclei formation in bystander cells was measured by using the cytokinesis block technique by adding cytochalasin B to the non irradiated culture together with the irradiated medium. Preliminary data indicate about 1.4-fold increase in micronuclei formation in

  10. Triple co-culture cell model as an in vitro model for oral particulate vaccine systems

    DEFF Research Database (Denmark)

    Nielsen, Line Hagner; De Rossi, C.; Lehr, C.-M.

    the immunostimulatory ability of particulate vaccine formulations designed for oral delivery. Levels of cytokine production in response to vaccine administration were measured following particulate vaccine administration, as an indication of dendritic cell and macrophage activation. Precursors of cubosomes containing......; this was not observed with ovalbumin and blank solution. An example of the results is shown in Figure 2 for IL-17A. An established co-culture of Caco-2, THP-1 and MUTZ-3 cells showed promise as an in vitro model for testing of oral vaccine formulations. Mobility of co-culture immune cells as well as cytokine production...... with particle formulations. This was not the case when incubating with ovalbumin solution or blank. The ELISA screening assay showed production of a wide range of cytokines following culture incubation with cubosomes (with and without ovalbumin) and LPS solutions, indicative of a stimulatory effect...

  11. Control oriented modeling of ejector in anode gas recirculation solid oxygen fuel cell systems

    International Nuclear Information System (INIS)

    Zhu Yinhai; Li Yanzhong; Cai Wenjian

    2011-01-01

    A one-equation model is proposed for fuel ejector in anode gas recirculation solid oxide fuel cell (SOFC) system. Firstly, the fundamental governing equations are established by employing the thermodynamic, fluid dynamic principles and chemical constraints inside the ejector; secondly, the one-equation model is derived by using the parameter analysis and lumped-parameter method. Finally, the computational fluid dynamics (CFD) technique is employed to obtain the source data for determining the model parameters. The effectiveness of the model is studied under a wide range of operation conditions. The effect of ejector performance on the anode gas recirculation SOFC system is also discussed. The presented model, which only contains four constant parameters, is useful in real-time control and optimization of fuel ejector in the anode gas recirculation SOFC system.

  12. The female gametophyte: an emerging model for cell type-specific systems biology in plant development

    Directory of Open Access Journals (Sweden)

    Marc William Schmid

    2015-11-01

    Full Text Available Systems biology, a holistic approach describing a system emerging from the interactions of its molecular components, critically depends on accurate qualitative determination and quantitative measurements of these components. Development and improvement of large-scale profiling methods (omics now facilitates comprehensive measurements of many relevant molecules. For multicellular organisms, such as animals, fungi, algae, and plants, the complexity of the system is augmented by the presence of specialized cell types and organs, and a complex interplay within and between them. Cell type-specific analyses are therefore crucial for the understanding of developmental processes and environmental responses. This review first gives an overview of current methods used for large-scale profiling of specific cell types exemplified by recent advances in plant biology. The focus then lies on suitable model systems to study plant development and cell type specification. We introduce the female gametophyte of flowering plants as an ideal model to study fundamental developmental processes. Moreover, the female reproductive lineage is of importance for the emergence of evolutionary novelties such as an unequal parental contribution to the tissue nurturing the embryo or the clonal production of seeds by asexual reproduction (apomixis. Understanding these processes is not only interesting from a developmental or evolutionary perspective, but bears great potential for further crop improvement and the simplification of breeding efforts. We finally highlight novel methods, which are already available or which will likely soon facilitate large-scale profiling of the specific cell types of the female gametophyte in both model and non-model species. We conclude that it may take only few years until an evolutionary systems biology approach toward female gametogenesis may decipher some of its biologically most interesting and economically most valuable processes.

  13. System modeling of an air-independent solid oxide fuel cell system for unmanned undersea vehicles

    Science.gov (United States)

    Burke, A. Alan; Carreiro, Louis G.

    To examine the feasibility of a solid oxide fuel cell (SOFC)-powered unmanned undersea vehicle (UUV), a system level analysis is presented that projects a possible integration of the SOFC stack, fuel steam reformer, fuel/oxidant storage and balance of plant components into a 21-in. diameter UUV platform. Heavy hydrocarbon fuel (dodecane) and liquid oxygen (LOX) are chosen as the preferred reactants. A maximum efficiency of 45% based on the lower heating value of dodecane was calculated for a system that provides 2.5 kW for 40 h. Heat sources and sinks have been coupled to show viable means of thermal management. The critical design issues involve proper recycling of exhaust steam from the fuel cell back into the reformer and effective use of the SOFC stack radiant heat for steam reformation of the hydrocarbon fuel.

  14. Elementary kinetic modelling applied to solid oxide fuel cell pattern anodes and a direct flame fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Marcel

    2009-05-27

    In the course of this thesis a model for the prediction of polarisation characteristics of solid oxide fuel cells (SOFC) was developed. The model is based on an elementary kinetic description of electrochemical reactions and the fundamental conservation principles of mass and energy. The model allows to predict the current-voltage relation of an SOFC and offers ideal possibilities for model validation. The aim of this thesis is the identification of rate-limiting processes and the determination of the elementary pathway during charge transfer. The numerical simulation of experiments with model anodes allowed to identify a hydrogen transfer to be the most probable charge-transfer reaction and revealed the influence of diffusive transport. Applying the hydrogen oxidation kinetics to the direct flame fuel cell system (DFFC) showed that electrochemical oxidation of CO is possible based on the same mechanism. Based on the quantification of loss processes in the DFFC system, improvements on cell design, predicting 80% increase of efficiency, were proposed. (orig.)

  15. Dynamic modeling and evaluation of solid oxide fuel cell - combined heat and power system operating strategies

    Science.gov (United States)

    Nanaeda, Kimihiro; Mueller, Fabian; Brouwer, Jacob; Samuelsen, Scott

    Operating strategies of solid oxide fuel cell (SOFC) combined heat and power (CHP) systems are developed and evaluated from a utility, and end-user perspective using a fully integrated SOFC-CHP system dynamic model that resolves the physical states, thermal integration and overall efficiency of the system. The model can be modified for any SOFC-CHP system, but the present analysis is applied to a hotel in southern California based on measured electric and heating loads. Analysis indicates that combined heat and power systems can be operated to benefit both the end-users and the utility, providing more efficient electric generation as well as grid ancillary services, namely dispatchable urban power. Design and operating strategies considered in the paper include optimal sizing of the fuel cell, thermal energy storage to dispatch heat, and operating the fuel cell to provide flexible grid power. Analysis results indicate that with a 13.1% average increase in price-of-electricity (POE), the system can provide the grid with a 50% operating range of dispatchable urban power at an overall thermal efficiency of 80%. This grid-support operating mode increases the operational flexibility of the SOFC-CHP system, which may make the technology an important utility asset for accommodating the increased penetration of intermittent renewable power.

  16. A cell-to-cell Markovian model for the reliability of a digital control system of a steam generator

    International Nuclear Information System (INIS)

    Gomes, Ian B.; Melo, Paulo F.F. Frutuoso e; Saldanha, Pedro L.C.

    2013-01-01

    With the shift of technology from analog to digital systems, due to the obsolescence of the older analog systems and the functional advantages of the digital ones, existing nuclear power plants have begun to replace their systems, while newer plants use digital systems from the beginning of their construction. However, the process of risk-informed analysis for digital systems has not been satisfactorily developed yet. Traditional methods, such as fault trees, have limitations, while dynamic methods are still in the tests stage and may be difficult to be applied to a real size probabilistic safety assessment (PSA) model. The objective of this paper is to study and obtain a better comprehension of the Markov/CCMT method, a method that combines the traditional Markovian methodology with the cell-to-cell mapping technique for representing the possible failure events that can be originated in the dynamic interactions between the instrumentation and control system and the controlled process, and among the various components of the digital system. The study consists of the simulation of a digital water level control system of the steam generator of a PWR plant. From this simulation, a Failure Modes and Effects Analysis (FMEA) was made and the information obtained was used to calculate the system reliability, using the Markov/CCMT methodology. The results show that the method is capable of identifying the most probable causes for a possible failure of the digital system. (author)

  17. Models and methods for design and implementation of computer based control and monitoring systems for production cells

    DEFF Research Database (Denmark)

    Lynggaard, Hans Jørgen Birk

    This dissertation is concerned with the engineering, i.e. the designing and making, of industrial cell control systems. The focus is on automated robot welding cells in the shipbuilding industry. The industrial research project defines models and methods for design and implementation of computer...... through the implementation of two cell control systems for robot welding cells in production at Odense Steel Shipyard.It is concluded that cell control technology provides for increased performance in production systems, and that the Cell Control Engineering concept reduces the effort for providing high...... quality and high functionality cell control solutions for the industry....

  18. Dynamic modeling of gas turbines in integrated gasification fuel cell systems

    Science.gov (United States)

    Maclay, James Davenport

    2009-12-01

    Solid oxide fuel cell-gas turbine (SOFC-GT) hybrid systems for use in integrated gasification fuel cell (IGFC) systems operating on coal will stretch existing fossil fuel reserves, generate power with less environmental impact, while having a cost of electricity advantage over most competing technologies. However, the dynamic performance of a SOFC-GT in IGFC applications has not been previously studied in detail. Of particular importance is how the turbo-machinery will be designed, controlled and operated in such applications; this is the focus of the current work. Perturbation and dynamic response analyses using numerical SimulinkRTM models indicate that compressor surge is the predominant concern for safe dynamic turbo-machinery operation while shaft over-speed and excessive turbine inlet temperatures are secondary concerns. Fuel cell temperature gradients and anode-cathode differential pressures were found to be the greatest concerns for safe dynamic fuel cell operation. Two control strategies were compared, that of constant gas turbine shaft speed and constant fuel cell temperature, utilizing a variable speed gas turbine. Neither control strategy could eliminate all vulnerabilities during dynamic operation. Constant fuel cell temperature control ensures safe fuel cell operation, while constant speed control does not. However, compressor surge is more likely with constant fuel cell temperature control than with constant speed control. Design strategies that provide greater surge margin while utilizing constant fuel cell temperature control include increasing turbine design mass flow and decreasing turbine design inlet pressure, increasing compressor design pressure ratio and decreasing compressor design mass flow, decreasing plenum volume, decreasing shaft moment of inertia, decreasing fuel cell pressure drop, maintaining constant compressor inlet air temperature. However, these strategies in some cases incur an efficiency penalty. A broad comparison of cycles

  19. Influence of distributed delays on the dynamics of a generalized immune system cancerous cells interactions model

    Science.gov (United States)

    Piotrowska, M. J.; Bodnar, M.

    2018-01-01

    We present a generalisation of the mathematical models describing the interactions between the immune system and tumour cells which takes into account distributed time delays. For the analytical study we do not assume any particular form of the stimulus function describing the immune system reaction to presence of tumour cells but we only postulate its general properties. We analyse basic mathematical properties of the considered model such as existence and uniqueness of the solutions. Next, we discuss the existence of the stationary solutions and analytically investigate their stability depending on the forms of considered probability densities that is: Erlang, triangular and uniform probability densities separated or not from zero. Particular instability results are obtained for a general type of probability densities. Our results are compared with those for the model with discrete delays know from the literature. In addition, for each considered type of probability density, the model is fitted to the experimental data for the mice B-cell lymphoma showing mean square errors at the same comparable level. For estimated sets of parameters we discuss possibility of stabilisation of the tumour dormant steady state. Instability of this steady state results in uncontrolled tumour growth. In order to perform numerical simulation, following the idea of linear chain trick, we derive numerical procedures that allow us to solve systems with considered probability densities using standard algorithm for ordinary differential equations or differential equations with discrete delays.

  20. Brain Aggregates: An Effective In Vitro Cell Culture System Modeling Neurodegenerative Diseases.

    Science.gov (United States)

    Ahn, Misol; Kalume, Franck; Pitstick, Rose; Oehler, Abby; Carlson, George; DeArmond, Stephen J

    2016-03-01

    Drug discovery for neurodegenerative diseases is particularly challenging because of the discrepancies in drug effects between in vitro and in vivo studies. These discrepancies occur in part because current cell culture systems used for drug screening have many limitations. First, few cell culture systems accurately model human aging or neurodegenerative diseases. Second, drug efficacy may differ between dividing and stationary cells, the latter resembling nondividing neurons in the CNS. Brain aggregates (BrnAggs) derived from embryonic day 15 gestation mouse embryos may represent neuropathogenic processes in prion disease and reflect in vivo drug efficacy. Here, we report a new method for the production of BrnAggs suitable for drug screening and suggest that BrnAggs can model additional neurological diseases such as tauopathies. We also report a functional assay with BrnAggs by measuring electrophysiological activities. Our data suggest that BrnAggs could serve as an effective in vitro cell culture system for drug discovery for neurodegenerative diseases. © 2016 American Association of Neuropathologists, Inc. All rights reserved.

  1. Non-linear model reduction and control of molten carbonate fuel cell systems with internal reforming

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Min

    2007-10-12

    Currently, the process design of fuel cells and the development of control strategies is mainly based on heuristic methods. Fuel cell models are often too complex for control purposes, or they are developed for a specific type of fuel cell and valid only in a small range of operation conditions. The application of fuel cell models to controller design is still limited. Furthermore, suitable and simple-to-implement design strategies for fuel cell control remain an open area. There is thus a motivation for simplifying dynamic models for process control applications and for designing suitable control strategies for fuel cells. This is the main objective of this work. As an application example, the 250 kW industrial molten carbonate fuel cell (MCFC) system HotModule by MTU CFC Solutions, Germany is considered. A detailed dynamic two-dimensional spatially distributed cross-flow model of a MCFC from literature is taken as a starting point for the investigation. In Chapter 2, two simplified model versions are derived by incorporating additional physical assumptions. One of the simplified models is extended to a three-dimensional stack model to deal with physical and chemical phenomena in the stack. Simulations of the stack model are performed in Chapter 3 in order to calculate the mass and temperature distributions in the direction perpendicular to the electrode area. The other simplified model forms the basis for a low order reduced model that is derived in Chapter 4. The reduced-order model is constructed by application of the Karhunen-Loeve Galerkin method. The spatial temperature, concentration and potential profiles are approximated by a set of orthogonal time independent spatial basis functions. Problem specific basis functions are generated numerically from simulation data of the detailed reference model. The advantage of this approach is that a small number of basis functions suffices in order to approximate the solution of the detailed model very well. The

  2. Stability characterization and modeling of robust distributed benthic microbial fuel cell (DBMFC) system.

    Science.gov (United States)

    Karra, Udayarka; Huang, Guoxian; Umaz, Ridvan; Tenaglier, Christopher; Wang, Lei; Li, Baikun

    2013-09-01

    A novel and robust distributed benthic microbial fuel cell (DBMFC) was developed to address the energy supply issues for oceanographic sensor network applications, especially under scouring and bioturbation by aquatic life. Multi-anode/cathode configuration was employed in the DBMFC system for enhanced robustness and stability in the harsh ocean environment. The results showed that the DBMFC system achieved peak power and current densities of 190mW/m(2) and 125mA/m(2) respectively. Stability characterization tests indicated the DBMFC with multiple anodes achieved higher power generation over the systems with single anode. A computational model that integrated physical, electrochemical and biological factors of MFCs was developed to validate the overall performance of the DBMFC system. The model simulation well corresponded with the experimental results, and confirmed the hypothesis that using a multi anode/cathode MFC configuration results in reliable and robust power generation. Published by Elsevier Ltd.

  3. Rule-based modeling: a computational approach for studying biomolecular site dynamics in cell signaling systems

    Science.gov (United States)

    Chylek, Lily A.; Harris, Leonard A.; Tung, Chang-Shung; Faeder, James R.; Lopez, Carlos F.

    2013-01-01

    Rule-based modeling was developed to address the limitations of traditional approaches for modeling chemical kinetics in cell signaling systems. These systems consist of multiple interacting biomolecules (e.g., proteins), which themselves consist of multiple parts (e.g., domains, linear motifs, and sites of phosphorylation). Consequently, biomolecules that mediate information processing generally have the potential to interact in multiple ways, with the number of possible complexes and post-translational modification states tending to grow exponentially with the number of binary interactions considered. As a result, only large reaction networks capture all possible consequences of the molecular interactions that occur in a cell signaling system, which is problematic because traditional modeling approaches for chemical kinetics (e.g., ordinary differential equations) require explicit network specification. This problem is circumvented through representation of interactions in terms of local rules. With this approach, network specification is implicit and model specification is concise. Concise representation results in a coarse graining of chemical kinetics, which is introduced because all reactions implied by a rule inherit the rate law associated with that rule. Coarse graining can be appropriate if interactions are modular, and the coarseness of a model can be adjusted as needed. Rules can be specified using specialized model-specification languages, and recently developed tools designed for specification of rule-based models allow one to leverage powerful software engineering capabilities. A rule-based model comprises a set of rules, which can be processed by general-purpose simulation and analysis tools to achieve different objectives (e.g., to perform either a deterministic or stochastic simulation). PMID:24123887

  4. Rule-based modeling: a computational approach for studying biomolecular site dynamics in cell signaling systems.

    Science.gov (United States)

    Chylek, Lily A; Harris, Leonard A; Tung, Chang-Shung; Faeder, James R; Lopez, Carlos F; Hlavacek, William S

    2014-01-01

    Rule-based modeling was developed to address the limitations of traditional approaches for modeling chemical kinetics in cell signaling systems. These systems consist of multiple interacting biomolecules (e.g., proteins), which themselves consist of multiple parts (e.g., domains, linear motifs, and sites of phosphorylation). Consequently, biomolecules that mediate information processing generally have the potential to interact in multiple ways, with the number of possible complexes and posttranslational modification states tending to grow exponentially with the number of binary interactions considered. As a result, only large reaction networks capture all possible consequences of the molecular interactions that occur in a cell signaling system, which is problematic because traditional modeling approaches for chemical kinetics (e.g., ordinary differential equations) require explicit network specification. This problem is circumvented through representation of interactions in terms of local rules. With this approach, network specification is implicit and model specification is concise. Concise representation results in a coarse graining of chemical kinetics, which is introduced because all reactions implied by a rule inherit the rate law associated with that rule. Coarse graining can be appropriate if interactions are modular, and the coarseness of a model can be adjusted as needed. Rules can be specified using specialized model-specification languages, and recently developed tools designed for specification of rule-based models allow one to leverage powerful software engineering capabilities. A rule-based model comprises a set of rules, which can be processed by general-purpose simulation and analysis tools to achieve different objectives (e.g., to perform either a deterministic or stochastic simulation). © 2013 Wiley Periodicals, Inc.

  5. 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...

  6. Pavement cells: a model system for non-transcriptional auxin signalling and crosstalks.

    Science.gov (United States)

    Chen, Jisheng; Wang, Fei; Zheng, Shiqin; Xu, Tongda; Yang, Zhenbiao

    2015-08-01

    Auxin (indole acetic acid) is a multifunctional phytohormone controlling various developmental patterns, morphogenetic processes, and growth behaviours in plants. The transcription-based pathway activated by the nuclear TRANSPORT INHIBITOR RESISTANT 1/auxin-related F-box auxin receptors is well established, but the long-sought molecular mechanisms of non-transcriptional auxin signalling remained enigmatic until very recently. Along with the establishment of the Arabidopsis leaf epidermal pavement cell (PC) as an exciting and amenable model system in the past decade, we began to gain insight into non-transcriptional auxin signalling. The puzzle-piece shape of PCs forms from intercalated or interdigitated cell growth, requiring local intra- and inter-cellular coordination of lobe and indent formation. Precise coordination of this interdigitated pattern requires auxin and an extracellular auxin sensing system that activates plasma membrane-associated Rho GTPases from plants and subsequent downstream events regulating cytoskeletal reorganization and PIN polarization. Apart from auxin, mechanical stress and cytokinin have been shown to affect PC interdigitation, possibly by interacting with auxin signals. This review focuses upon signalling mechanisms for cell polarity formation in PCs, with an emphasis on non-transcriptional auxin signalling in polarized cell expansion and pattern formation and how different auxin pathways interplay with each other and with other signals. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  7. An in-depth comparison of latent HIV-1 reactivation in multiple cell model systems and resting CD4+ T cells from aviremic patients.

    Directory of Open Access Journals (Sweden)

    Celsa A Spina

    Full Text Available The possibility of HIV-1 eradication has been limited by the existence of latently infected cellular reservoirs. Studies to examine control of HIV latency and potential reactivation have been hindered by the small numbers of latently infected cells found in vivo. Major conceptual leaps have been facilitated by the use of latently infected T cell lines and primary cells. However, notable differences exist among cell model systems. Furthermore, screening efforts in specific cell models have identified drug candidates for "anti-latency" therapy, which often fail to reactivate HIV uniformly across different models. Therefore, the activity of a given drug candidate, demonstrated in a particular cellular model, cannot reliably predict its activity in other cell model systems or in infected patient cells, tested ex vivo. This situation represents a critical knowledge gap that adversely affects our ability to identify promising treatment compounds and hinders the advancement of drug testing into relevant animal models and clinical trials. To begin to understand the biological characteristics that are inherent to each HIV-1 latency model, we compared the response properties of five primary T cell models, four J-Lat cell models and those obtained with a viral outgrowth assay using patient-derived infected cells. A panel of thirteen stimuli that are known to reactivate HIV by defined mechanisms of action was selected and tested in parallel in all models. Our results indicate that no single in vitro cell model alone is able to capture accurately the ex vivo response characteristics of latently infected T cells from patients. Most cell models demonstrated that sensitivity to HIV reactivation was skewed toward or against specific drug classes. Protein kinase C agonists and PHA reactivated latent HIV uniformly across models, although drugs in most other classes did not.

  8. An In-Depth Comparison of Latent HIV-1 Reactivation in Multiple Cell Model Systems and Resting CD4+ T Cells from Aviremic Patients

    Science.gov (United States)

    Spina, Celsa A.; Anderson, Jenny; Archin, Nancie M.; Bosque, Alberto; Chan, Jonathan; Famiglietti, Marylinda; Greene, Warner C.; Kashuba, Angela; Lewin, Sharon R.; Margolis, David M.; Mau, Matthew; Ruelas, Debbie; Saleh, Suha; Shirakawa, Kotaro; Siliciano, Robert F.; Singhania, Akul; Soto, Paula C.; Terry, Valeri H.; Verdin, Eric; Woelk, Christopher; Wooden, Stacey; Xing, Sifei; Planelles, Vicente

    2013-01-01

    The possibility of HIV-1 eradication has been limited by the existence of latently infected cellular reservoirs. Studies to examine control of HIV latency and potential reactivation have been hindered by the small numbers of latently infected cells found in vivo. Major conceptual leaps have been facilitated by the use of latently infected T cell lines and primary cells. However, notable differences exist among cell model systems. Furthermore, screening efforts in specific cell models have identified drug candidates for “anti-latency” therapy, which often fail to reactivate HIV uniformly across different models. Therefore, the activity of a given drug candidate, demonstrated in a particular cellular model, cannot reliably predict its activity in other cell model systems or in infected patient cells, tested ex vivo. This situation represents a critical knowledge gap that adversely affects our ability to identify promising treatment compounds and hinders the advancement of drug testing into relevant animal models and clinical trials. To begin to understand the biological characteristics that are inherent to each HIV-1 latency model, we compared the response properties of five primary T cell models, four J-Lat cell models and those obtained with a viral outgrowth assay using patient-derived infected cells. A panel of thirteen stimuli that are known to reactivate HIV by defined mechanisms of action was selected and tested in parallel in all models. Our results indicate that no single in vitro cell model alone is able to capture accurately the ex vivo response characteristics of latently infected T cells from patients. Most cell models demonstrated that sensitivity to HIV reactivation was skewed toward or against specific drug classes. Protein kinase C agonists and PHA reactivated latent HIV uniformly across models, although drugs in most other classes did not. PMID:24385908

  9. A 3D human neural cell culture system for modeling Alzheimer’s disease

    Science.gov (United States)

    Kim, Young Hye; Choi, Se Hoon; D’Avanzo, Carla; Hebisch, Matthias; Sliwinski, Christopher; Bylykbashi, Enjana; Washicosky, Kevin J.; Klee, Justin B.; Brüstle, Oliver; Tanzi, Rudolph E.; Kim, Doo Yeon

    2015-01-01

    Stem cell technologies have facilitated the development of human cellular disease models that can be used to study pathogenesis and test therapeutic candidates. These models hold promise for complex neurological diseases such as Alzheimer’s disease (AD) because existing animal models have been unable to fully recapitulate all aspects of pathology. We recently reported the characterization of a novel three-dimensional (3D) culture system that exhibits key events in AD pathogenesis, including extracellular aggregation of β-amyloid and accumulation of hyperphosphorylated tau. Here we provide instructions for the generation and analysis of 3D human neural cell cultures, including the production of genetically modified human neural progenitor cells (hNPCs) with familial AD mutations, the differentiation of the hNPCs in a 3D matrix, and the analysis of AD pathogenesis. The 3D culture generation takes 1–2 days. The aggregation of β-amyloid is observed after 6-weeks of differentiation followed by robust tau pathology after 10–14 weeks. PMID:26068894

  10. Modelling and control of solid oxide fuel cell generation system in microgrid

    Science.gov (United States)

    Zhou, Niancheng; Li, Chunyan; Sun, Fangqing; Wang, Qianggang

    2017-11-01

    Compared with other kinds of fuel cells, solid oxide fuel cell (SOFC) has been widely used in microgrids because of its higher efficiency and longer operation life. The weakness of SOFC lies in its slow response speed when grid disturbance occurs. This paper presents a control strategy that can promote the response speed and limit the fault current impulse for SOFC systems integrated into microgrids. First, the hysteretic control of the bidirectional DC-DC converter, which joins the SOFC and DC bus together, is explored. In addition, an improved droop control with limited current protection is applied in the DC-AC inverter, and the active synchronization control is applied to ensure a smooth transition of the microgrid between the grid-connected mode and the islanded mode. To validate the effectiveness of this control strategy, the control model was built and simulated in PSCAD/EMTDC.

  11. Using adaptive neuro fuzzy inference system (ANFIS) for proton exchange membrane fuel cell (PEMFC) performance modeling

    International Nuclear Information System (INIS)

    Rezazadeh, S.; Mirzaee, I.; Mehrabi, M.

    2012-01-01

    In this paper, an adaptive neuro fuzzy inference system (ANFIS) is used for modeling proton exchange membrane fuel cell (PEMFC) performance using some numerically investigated and compared with those to experimental results for training and test data. In this way, current density I (A/cm 2 ) is modeled to the variation of pressure at the cathode side P C (atm), voltage V (V), membrane thickness (mm), Anode transfer coefficient α an , relative humidity of inlet fuel RH a and relative humidity of inlet air RH c which are defined as input (design) variables. Then, we divided these data into train and test sections to do modeling. We instructed ANFIS network by 80% of numerical validated data. 20% of primary data which had been considered for testing the appropriateness of the models was entered ANFIS network models and results were compared by three statistical criterions. Considering the results, it is obvious that our proposed modeling by ANFIS is efficient and valid and it can be expanded for more general states

  12. Using adaptive neuro fuzzy inference system (ANFIS) for proton exchange membrane fuel cell (PEMFC) performance modeling

    Energy Technology Data Exchange (ETDEWEB)

    Rezazadeh, S.; Mirzaee, I. [Urmia Univ., Urmia (Iran, Islamic Republic of); Mehrabi, M. [University of Pretoria, Pretoria (South Africa)

    2012-11-15

    In this paper, an adaptive neuro fuzzy inference system (ANFIS) is used for modeling proton exchange membrane fuel cell (PEMFC) performance using some numerically investigated and compared with those to experimental results for training and test data. In this way, current density I (A/cm{sup 2}) is modeled to the variation of pressure at the cathode side P{sup C} (atm), voltage V (V), membrane thickness (mm), Anode transfer coefficient {alpha}{sup an}, relative humidity of inlet fuel RH{sup a} and relative humidity of inlet air RH{sup c} which are defined as input (design) variables. Then, we divided these data into train and test sections to do modeling. We instructed ANFIS network by 80% of numerical validated data. 20% of primary data which had been considered for testing the appropriateness of the models was entered ANFIS network models and results were compared by three statistical criterions. Considering the results, it is obvious that our proposed modeling by ANFIS is efficient and valid and it can be expanded for more general states.

  13. Modeling industrial centrifugation of mammalian cell culture using a capillary based scale-down system.

    Science.gov (United States)

    Westoby, Matthew; Rogers, Jameson K; Haverstock, Ryan; Romero, Jonathan; Pieracci, John

    2011-05-01

    Continuous-flow centrifugation is widely utilized as the primary clarification step in the recovery of biopharmaceuticals from cell culture. However, it is a challenging operation to develop and characterize due to the lack of easy to use, small-scale, systems that can be used to model industrial processes. As a result, pilot-scale continuous centrifugation is typically employed to model large-scale systems requiring a significant amount of resources. In an effort to reduce resource requirements and create a system which is easy to construct and utilize, a capillary shear device, capable of producing energy dissipation rates equivalent to those present in the feed zones of industrial disk stack centrifuges, was developed and evaluated. When coupled to a bench-top, batch centrifuge, the capillary device reduced centrate turbidity prediction error from 37% to 4% compared to using a bench-top centrifuge alone. Laboratory-scale parameters that are analogous to those routinely varied during industrial-scale continuous centrifugation were identified and evaluated for their utility in emulating disk stack centrifuge performance. The resulting relationships enable bench-scale process modeling of continuous disk stack centrifuges using an easily constructed, scalable, capillary shear device coupled to a typical bench-top centrifuge. Copyright © 2010 Wiley Periodicals, Inc.

  14. Effects of Gamma irradiation on uronic acid sugars as cell wall polysaccharide model systems

    International Nuclear Information System (INIS)

    Irawati, Zubaidah; Pilnik, W.

    2001-01-01

    Irradiation is an alternative preservation method with can be utilized to extend the self-life of agricultural products by eliminating number of insects, and decreasing microbial growth effectively. Cell wall polysaccharides which mainly consist of pectic substances, hemicelluloses and cellulose play a major role on the immediate fruits. their degradation mechanism can be elucidates by studying their degradation products resulting from the irradiated cell wall or cell wall components. Isolated apple pectin and alginates as different in solid state by gamma irradiation at 15-30 kGy under two different humidities. The parameters observed were viscosity, β-elimination in the ester groups of pectin, and distribution of molecular weight. Irradiation with the doses of 15-30 kGy could reduce the viscosity of pectin and alginates, while irradiation did not cause β-elimination in the ester groups of pectin as confirmed by titration and ion exchange chromatography methods. The formation of 4,5-unsaturated uronosyl residues as a product of cleavage of the pectin backbone via- β-elimination was not found in irradiated pectin as confirmed by thio barbiture acid (TBA) test. High Performance Size Exclusion Chromatography (HPSEC) analysis for the irradiated polysaccharide model systems revealed that the average number of molecular weight showed a decrease by increasing radiation dose. Storage condition in two different relative humidities affected significantly the degree of polymerization of pectin and alginates in solid state

  15. Modeling and optimization for proton exchange membrane fuel cell stack using aging and challenging P systems based optimization algorithm

    International Nuclear Information System (INIS)

    Yang, Shipin; Chellali, Ryad; Lu, Xiaohua; Li, Lijuan; Bo, Cuimei

    2016-01-01

    Accurate models of PEM (proton exchange membrane) fuel cells are of great significance for the analysis and the control for power generation. We present a new semi-empirical model to predict the voltage outputs of PEM fuel cell stacks. We also introduce a new estimation method, called AC-POA (aging and challenging P systems based optimization algorithm) allowing deriving the parameters of the semi-empirical model. In our model, the cathode inlet pressure is selected as an additional factor to modify the expression of concentration over-voltage V con for traditional Amphlett's PEM fuel cell model. In AC-POA, the aging-mechanism inspired object updating rule is merged in existing P system. We validate through experiments the effectiveness of AC-POA and the fitting accuracy of our model. Modeling comparison results show that the predictions of our model are the best in terms of fitting to actual sample data. - Highlights: • Presented a p c -based modificatory semi-empirical model for PEMFC stack. • Introduced a new aging inspired improved parameter estimation algorithm, AC-POA. • Validated the effectiveness of the AC-POA and the new model. • Remodeled the practical PEM fuel cell system.

  16. "A Cellular Encounter": Constructing the Cell as a Whole System Using Illustrative Models

    Science.gov (United States)

    Cohen, Joel I.

    2014-01-01

    A standard part of biology curricula is a project-based assessment of cell structure and function. However, these are often individual assignments that promote little problem-solving or group learning and avoid the subject of organelle chemical interactions. I evaluate a model-based cell project designed to foster group and individual guided…

  17. A theoretical model of naturally occurring cell death in the nervous system

    OpenAIRE

    Galli, Resta; Resta, Giovanni

    1991-01-01

    Throughout the animal kingdom, the formation of the nervous system involves the elimination of many cells, soon after their generation. This phenomenon, known as naturally occurring cell death, has precise time schedules, is observed in the vast majority of nervous structures and causes the 1oss of 15 - 85% of the neurones generated initially. Elimination of erroneous projections, as well as proper size matching between connecting structures can be achieved through cell death. However if elim...

  18. Optimization of a fuel cell system based on empirical data of a PEM fuel cell stack and the generalized electrochemical model. Paper no. IGEC-1-126

    International Nuclear Information System (INIS)

    Wishart, J.; Secanell, M.; Dong, Z.; Wang, G.

    2005-01-01

    A fuel cell system model is implemented in MATLAB in order to optimize the system operating conditions. The implemented fuel cell model is a modified version of the semi-empirical model introduced by researchers at the Royal Military College of Canada. In addition, in order to model the whole fuel cell system, heat transfer and gas flow considerations and the associated Balance of Plant (BOP) components are incorporated into the model. System design optimizations are carried out using three different methods, including the sequential quadratic programming (SQP) local optimization algorithm and simulated annealing (SA) and genetic algorithm (GA) global optimization algorithms. Using the operating conditions of the fuel cell system as the design variables, the net output power of the system is optimized. The three methods are used in order to gain some insight into the nature of the objective function and the performance of the different algorithms. The optimization results show a good agreement and provide useful information on the design optimization problem. This study prepares us for more complex modeling and system optimization research. (author)

  19. Yersinia enterocolitica targets cells of the innate and adaptive immune system by injection of Yops in a mouse infection model.

    Directory of Open Access Journals (Sweden)

    Martin Köberle

    2009-08-01

    Full Text Available Yersinia enterocolitica (Ye evades the immune system of the host by injection of Yersinia outer proteins (Yops via a type three secretion system into host cells. In this study, a reporter system comprising a YopE-beta-lactamase hybrid protein and a fluorescent staining sensitive to beta-lactamase cleavage was used to track Yop injection in cell culture and in an experimental Ye mouse infection model. Experiments with GD25, GD25-beta1A, and HeLa cells demonstrated that beta1-integrins and RhoGTPases play a role for Yop injection. As demonstrated by infection of splenocyte suspensions in vitro, injection of Yops appears to occur randomly into all types of leukocytes. In contrast, upon infection of mice, Yop injection was detected in 13% of F4/80(+, 11% of CD11c(+, 7% of CD49b(+, 5% of Gr1(+ cells, 2.3% of CD19(+, and 2.6% of CD3(+ cells. Taking the different abundance of these cell types in the spleen into account, the highest total number of Yop-injected cells represents B cells, particularly CD19(+CD21(+CD23(+ follicular B cells, followed by neutrophils, dendritic cells, and macrophages, suggesting a distinct cellular tropism of Ye. Yop-injected B cells displayed a significantly increased expression of CD69 compared to non-Yop-injected B cells, indicating activation of these cells by Ye. Infection of IFN-gammaR (receptor- and TNFRp55-deficient mice resulted in increased numbers of Yop-injected spleen cells for yet unknown reasons. The YopE-beta-lactamase hybrid protein reporter system provides new insights into the modulation of host cell and immune responses by Ye Yops.

  20. Modeling efficiency and water balance in PEM fuel cell systems with liquid fuel processing and hydrogen membranes

    Science.gov (United States)

    Pearlman, Joshua B.; Bhargav, Atul; Shields, Eric B.; Jackson, Gregory S.; Hearn, Patrick L.

    Integrating PEM fuel cells effectively with liquid hydrocarbon reforming requires careful system analysis to assess trade-offs associated with H 2 production, purification, and overall water balance. To this end, a model of a PEM fuel cell system integrated with an autothermal reformer for liquid hydrocarbon fuels (modeled as C 12H 23) and with H 2 purification in a water-gas-shift/membrane reactor is developed to do iterative calculations for mass, species, and energy balances at a component and system level. The model evaluates system efficiency with parasitic loads (from compressors, pumps, and cooling fans), system water balance, and component operating temperatures/pressures. Model results for a 5-kW fuel cell generator show that with state-of-the-art PEM fuel cell polarization curves, thermal efficiencies >30% can be achieved when power densities are low enough for operating voltages >0.72 V per cell. Efficiency can be increased by operating the reformer at steam-to-carbon ratios as high as constraints related to stable reactor temperatures allow. Decreasing ambient temperature improves system water balance and increases efficiency through parasitic load reduction. The baseline configuration studied herein sustained water balance for ambient temperatures ≤35 °C at full power and ≤44 °C at half power with efficiencies approaching ∼27 and ∼30%, respectively.

  1. Determination of optimal reformer temperature in a reformed methanol fuel cell system using ANFIS models and numerical optimization methods

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl

    2015-01-01

    In this work a method for choosing the optimal reformer temperature for a reformed methanol fuel cell system is presented based on a case study of a H3 350 module produced by Serenergy A/S. The method is based on ANFIS models of the dependence of the reformer output gas composition on the reformer...... temperature and fuel flow, and the dependence of the fuel cell voltage on the fuel cell temperature, current and anode supply gas CO content. These models are combined to give a matrix of system efficiencies at different fuel cell currents and reformer temperatures. This matrix is then used to find...... the reformer temperature which gives the highest efficiency for each fuel cell current. The average of this optimal efficiency curve is 32.11% and the average efficiency achieved using the standard constant temperature is 30.64% an increase of 1.47 percentage points. The gain in efficiency is 4 percentage...

  2. A tri-generation system based on polymer electrolyte fuel cell and desiccant wheel – Part A: Fuel cell system modelling and partial load analysis

    International Nuclear Information System (INIS)

    Najafi, Behzad; De Antonellis, Stefano; Intini, Manuel; Zago, Matteo; Rinaldi, Fabio; Casalegno, Andrea

    2015-01-01

    Highlights: • A mathematical model for a PEMFC based cogeneration system is developed. • Developed model is validated using the available experimental data. • Performance of the plant at full load conditions is investigated. • Performance indices while applying two different modifications are determined. • System’s performance with and without modifications at partial loads is investigated. - Abstract: Polymer Electrolyte Membrane Fuel Cell (PEMFC) based systems have recently received increasing attention as a viable alternative for meeting the residential electrical and thermal demands. However, as the intermittent demand profiles of a building can only be addressed by a tri-generative unit which can operate at partial loads, the variation of performance of the system at partial loads might affect its corresponding potential benefits significantly. Nonetheless, no previous study has been carried out on assessing the performance of this type of tri-generative systems in such conditions. The present paper is the first of a two part study dedicated to the investigation of the performance of a tri-generative system in which a PEMFC based system is coupled with a desiccant wheel unit. This study is focused on evaluating the performance of the PEMFC subsystem while operating at partial loads. Accordingly, a detailed mathematical model of the fuel cell subsystem is first developed and validated using the experimental data obtained from the plant’s and the fuel cell stack’s manufacturer. Next, in order to increase the performance of the plant, two modifications have been proposed and the resulting performance at partial load have been determined. The obtained results demonstrate that applying both modifications results in increasing the electrical efficiency of the plant by 5.5%. It is also shown that, while operating at partial loads, the electrical efficiency of the plant does not significantly change; the fact which corresponds to the trade-off between

  3. Generation of an ICF syndrome model by efficient genome editing of human induced pluripotent stem cells using the CRISPR system.

    Science.gov (United States)

    Horii, Takuro; Tamura, Daiki; Morita, Sumiyo; Kimura, Mika; Hatada, Izuho

    2013-09-30

    Genome manipulation of human induced pluripotent stem (iPS) cells is essential to achieve their full potential as tools for regenerative medicine. To date, however, gene targeting in human pluripotent stem cells (hPSCs) has proven to be extremely difficult. Recently, an efficient genome manipulation technology using the RNA-guided DNase Cas9, the clustered regularly interspaced short palindromic repeats (CRISPR) system, has been developed. Here we report the efficient generation of an iPS cell model for immunodeficiency, centromeric region instability, facial anomalies syndrome (ICF) syndrome using the CRISPR system. We obtained iPS cells with mutations in both alleles of DNA methyltransferase 3B (DNMT3B) in 63% of transfected clones. Our data suggest that the CRISPR system is highly efficient and useful for genome engineering of human iPS cells.

  4. Generation of an ICF Syndrome Model by Efficient Genome Editing of Human Induced Pluripotent Stem Cells Using the CRISPR System

    Directory of Open Access Journals (Sweden)

    Izuho Hatada

    2013-09-01

    Full Text Available Genome manipulation of human induced pluripotent stem (iPS cells is essential to achieve their full potential as tools for regenerative medicine. To date, however, gene targeting in human pluripotent stem cells (hPSCs has proven to be extremely difficult. Recently, an efficient genome manipulation technology using the RNA-guided DNase Cas9, the clustered regularly interspaced short palindromic repeats (CRISPR system, has been developed. Here we report the efficient generation of an iPS cell model for immunodeficiency, centromeric region instability, facial anomalies syndrome (ICF syndrome using the CRISPR system. We obtained iPS cells with mutations in both alleles of DNA methyltransferase 3B (DNMT3B in 63% of transfected clones. Our data suggest that the CRISPR system is highly efficient and useful for genome engineering of human iPS cells.

  5. Bioengineering a 3D integumentary organ system from iPS cells using an in vivo transplantation model.

    Science.gov (United States)

    Takagi, Ryoji; Ishimaru, Junko; Sugawara, Ayaka; Toyoshima, Koh-Ei; Ishida, Kentaro; Ogawa, Miho; Sakakibara, Kei; Asakawa, Kyosuke; Kashiwakura, Akitoshi; Oshima, Masamitsu; Minamide, Ryohei; Sato, Akio; Yoshitake, Toshihiro; Takeda, Akira; Egusa, Hiroshi; Tsuji, Takashi

    2016-04-01

    The integumentary organ system is a complex system that plays important roles in waterproofing, cushioning, protecting deeper tissues, excreting waste, and thermoregulation. We developed a novel in vivo transplantation model designated as a clustering-dependent embryoid body transplantation method and generated a bioengineered three-dimensional (3D) integumentary organ system, including appendage organs such as hair follicles and sebaceous glands, from induced pluripotent stem cells. This bioengineered 3D integumentary organ system was fully functional following transplantation into nude mice and could be properly connected to surrounding host tissues, such as the epidermis, arrector pili muscles, and nerve fibers, without tumorigenesis. The bioengineered hair follicles in the 3D integumentary organ system also showed proper hair eruption and hair cycles, including the rearrangement of follicular stem cells and their niches. Potential applications of the 3D integumentary organ system include an in vitro assay system, an animal model alternative, and a bioengineered organ replacement therapy.

  6. DNA damage, metabolism and aging in pro-inflammatory T cells: Rheumatoid arthritis as a model system.

    Science.gov (United States)

    Li, Yinyin; Goronzy, Jörg J; Weyand, Cornelia M

    2018-05-01

    The aging process is the major driver of morbidity and mortality, steeply increasing the risk to succumb to cancer, cardiovascular disease, infection and neurodegeneration. Inflammation is a common denominator in age-related pathologies, identifying the immune system as a gatekeeper in aging overall. Among immune cells, T cells are long-lived and exposed to intense replication pressure, making them sensitive to aging-related abnormalities. In successful T cell aging, numbers of naïve cells, repertoire diversity and activation thresholds are preserved as long as possible; in maladaptive T cell aging, protective T cell functions decline and pro-inflammatory effector cells are enriched. Here, we review in the model system of rheumatoid arthritis (RA) how maladaptive T cell aging renders the host susceptible to chronic, tissue-damaging inflammation. In T cells from RA patients, known to be about 20years pre-aged, three interconnected functional domains are altered: DNA damage repair, metabolic activity generating energy and biosynthetic precursor molecules, and shaping of plasma membranes to promote T cell motility. In each of these domains, key molecules and pathways have now been identified, including the glycolytic enzymes PFKFB3 and G6PD; the DNA repair molecules ATM, DNA-PKcs and MRE11A; and the podosome marker protein TKS5. Some of these molecules may help in defining targetable pathways to slow the T cell aging process. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Modeling and Nonlinear Control of Fuel Cell / Supercapacitor Hybrid Energy Storage System for Electric Vehicles

    DEFF Research Database (Denmark)

    El Fadil, Hassan; Giri, Fouad; Guerrero, Josep M.

    2014-01-01

    This paper deals with the problem of controlling hybrid energy storage system (HESS) for electric vehicle. The storage system consists of a fuel cell (FC), serving as the main power source, and a supercapacitor (SC), serving as an auxiliary power source. It also contains a power block for energy...

  8. PEM Fuel Cells with Bio-Ethanol Processor Systems A Multidisciplinary Study of Modelling, Simulation, Fault Diagnosis and Advanced Control

    CERN Document Server

    Feroldi, Diego; Outbib, Rachid

    2012-01-01

    An apparently appropriate control scheme for PEM fuel cells may actually lead to an inoperable plant when it is connected to other unit operations in a process with recycle streams and energy integration. PEM Fuel Cells with Bio-Ethanol Processor Systems presents a control system design that provides basic regulation of the hydrogen production process with PEM fuel cells. It then goes on to construct a fault diagnosis system to improve plant safety above this control structure. PEM Fuel Cells with Bio-Ethanol Processor Systems is divided into two parts: the first covers fuel cells and the second discusses plants for hydrogen production from bio-ethanol to feed PEM fuel cells. Both parts give detailed analyses of modeling, simulation, advanced control, and fault diagnosis. They give an extensive, in-depth discussion of the problems that can occur in fuel cell systems and propose a way to control these systems through advanced control algorithms. A significant part of the book is also given over to computer-aid...

  9. The planarian flatworm: an in vivo model for stem cell biology and nervous system regeneration

    Directory of Open Access Journals (Sweden)

    Luca Gentile

    2011-01-01

    Full Text Available Planarian flatworms are an exception among bilaterians in that they possess a large pool of adult stem cells that enables them to promptly regenerate any part of their body, including the brain. Although known for two centuries for their remarkable regenerative capabilities, planarians have only recently emerged as an attractive model for studying regeneration and stem cell biology. This revival is due in part to the availability of a sequenced genome and the development of new technologies, such as RNA interference and next-generation sequencing, which facilitate studies of planarian regeneration at the molecular level. Here, we highlight why planarians are an exciting tool in the study of regeneration and its underlying stem cell biology in vivo, and discuss the potential promises and current limitations of this model organism for stem cell research and regenerative medicine.

  10. Bioengineering a 3D integumentary organ system from iPS cells using an in vivo transplantation model

    OpenAIRE

    Takagi, Ryoji; Ishimaru, Junko; Sugawara, Ayaka; Toyoshima, Koh-ei; Ishida, Kentaro; Ogawa, Miho; Sakakibara, Kei; Asakawa, Kyosuke; Kashiwakura, Akitoshi; Oshima, Masamitsu; Minamide, Ryohei; Sato, Akio; Yoshitake, Toshihiro; Takeda, Akira; Egusa, Hiroshi

    2016-01-01

    The integumentary organ system is a complex system that plays important roles in waterproofing, cushioning, protecting deeper tissues, excreting waste, and thermoregulation. We developed a novel in vivo transplantation model designated as a clustering-dependent embryoid body transplantation method and generated a bioengineered three-dimensional (3D) integumentary organ system, including appendage organs such as hair follicles and sebaceous glands, from induced pluripotent stem cells. This bio...

  11. The Effect of Primary Cancer Cell Culture Models on the Results of Drug Chemosensitivity Assays: The Application of Perfusion Microbioreactor System as Cell Culture Vessel

    Science.gov (United States)

    Chen, Yi-Dao; Huang, Shiang-Fu; Wang, Hung-Ming

    2015-01-01

    To precisely and faithfully perform cell-based drug chemosensitivity assays, a well-defined and biologically relevant culture condition is required. For the former, a perfusion microbioreactor system capable of providing a stable culture condition was adopted. For the latter, however, little is known about the impact of culture models on the physiology and chemosensitivity assay results of primary oral cavity cancer cells. To address the issues, experiments were performed. Results showed that minor environmental pH change could significantly affect the metabolic activity of cells, demonstrating the importance of stable culture condition for such assays. Moreover, the culture models could also significantly influence the metabolic activity and proliferation of cells. Furthermore, the choice of culture models might lead to different outcomes of chemosensitivity assays. Compared with the similar test based on tumor-level assays, the spheroid model could overestimate the drug resistance of cells to cisplatin, whereas the 2D and 3D culture models might overestimate the chemosensitivity of cells to such anticancer drug. In this study, the 3D culture models with same cell density as that in tumor samples showed comparable chemosensitivity assay results as the tumor-level assays. Overall, this study has provided some fundamental information for establishing a precise and faithful drug chemosensitivity assay. PMID:25654105

  12. Development of a model system to study leukotriene-induced modification of radiation sensitivity in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Walden, Jr, T L; Holahan, Jr, E V; Catravas, G N

    1986-01-01

    Leukotrienes (LT) are an important class of biological mediators for which no information exists concerning their synthesis following a radiation insult or on their ability to modify cellular response to a subsequent radiation exposure. Results are presented which illustrate that the Chinese hamster lung fibroblast cell line, V79A03, is useful as a model system to study the metabolic fate of leukotrienes and the effect of LT on radiation sensitivity of mammalian cells in vitro. (U.K.).

  13. Conserved host response to highly pathogenic avian influenza virus infection in human cell culture, mouse and macaque model systems

    Directory of Open Access Journals (Sweden)

    McDermott Jason E

    2011-11-01

    Full Text Available Abstract Background Understanding host response to influenza virus infection will facilitate development of better diagnoses and therapeutic interventions. Several different experimental models have been used as a proxy for human infection, including cell cultures derived from human cells, mice, and non-human primates. Each of these systems has been studied extensively in isolation, but little effort has been directed toward systematically characterizing the conservation of host response on a global level beyond known immune signaling cascades. Results In the present study, we employed a multivariate modeling approach to characterize and compare the transcriptional regulatory networks between these three model systems after infection with a highly pathogenic avian influenza virus of the H5N1 subtype. Using this approach we identified functions and pathways that display similar behavior and/or regulation including the well-studied impact on the interferon response and the inflammasome. Our results also suggest a primary response role for airway epithelial cells in initiating hypercytokinemia, which is thought to contribute to the pathogenesis of H5N1 viruses. We further demonstrate that we can use a transcriptional regulatory model from the human cell culture data to make highly accurate predictions about the behavior of important components of the innate immune system in tissues from whole organisms. Conclusions This is the first demonstration of a global regulatory network modeling conserved host response between in vitro and in vivo models.

  14. Modeling the integration of thermoelectrics in anode exhaust combustors for waste heat recovery in fuel cell systems

    Science.gov (United States)

    Maghdouri Moghaddam, Anita

    Recently developed small-scale hydrocarbon-fueled fuel cell systems for portable power under 1 kW have overall system efficiencies typically no higher than 30-35%. This study explores the possibility of using of thermoelectric waste heat recovery in anode exhaust combustors to improve the fuel cell system efficiencies by as much as 4-5% points and further to reduce required battery power during system start-up. Two models were used to explore this. The first model simulated an integrated SOFC system with a simplified catalytic combustor model with TEs integrated between the combustor and air preheating channels for waste heat recovery. This model provided the basis for assessing how much additional power can achieve during SOFC operation as a function of fuel cell operating conditions. Results for the SOFC system indicate that while the TEs may recover as much as 4% of the total fuel energy into the system, their benefit is reduced in part because they reduce the waste heat transferred back to the incoming air stream and thereby lower the SOFC operating temperatures and operating efficiencies. A second model transient model of a TE-integrated catalytic combustor explored the performance of the TEs during transient start-up of the combustor. This model incorporated more detailed catalytic combustion chemistry and enhanced cooling air fin heat transfer to show the dynamic heating of the integrated combustor. This detailed model provided a basis for exploring combustor designs and showed the importance of adequate reactant preheating when burning exhaust from a reformer during start-up for the TEs to produce significant power to reduce the size of system batteries for start-up.

  15. Market penetration analysis of fuel cell vehicles in Japan by using the energy system model MARKAL

    International Nuclear Information System (INIS)

    Endo, Eiichi

    2007-01-01

    The objective of the present work is to validate the hydrogen energy roadmap of Japan by analyzing the market penetration of fuel cell vehicles (FCVs) and the effects of a carbon tax using an energy system model of Japan based on MARKAL. The results of the analysis show that a hydrogen FCV would not be cost competitive until 2050 without a more severe carbon tax than the government's planned 2400 JPY/t-C carbon tax. However, as the carbon tax rate increases, instead of conventional vehicles including the gasoline hybrid electric vehicle, hydrogen FCVs gain market penetration earlier and more. By assuming a more severe carbon tax rate, such as 10 000 JPY/t-C, the market share of hydrogen FCVs approaches the governmental goal. This suggests that cheaper vehicle cost and hydrogen cost than those targeted in the roadmap should be attained or subsidies to hydrogen FCV and hydrogen refueling station will be necessary for achieving the goal of earlier market penetration. (author)

  16. Development of an in situ evaluation system for neural cells using extracellular matrix-modeled gel culture.

    Science.gov (United States)

    Nagai, Takayuki; Ikegami, Yasuhiro; Mizumachi, Hideyuki; Shirakigawa, Nana; Ijima, Hiroyuki

    2017-10-01

    Two-dimensional monolayer culture is the most popular cell culture method. However, the cells may not respond as they do in vivo because the culture conditions are different from in vivo conditions. However, hydrogel-embedding culture, which cultures cells in a biocompatible culture substrate, can produce in vivo-like cell responses, but in situ evaluation of cells in a gel is difficult. In this study, we realized an in vivo-like environment in vitro to produce cell responses similar to those in vivo and established an in situ evaluation system for hydrogel-embedded cell responses. The extracellular matrix (ECM)-modeled gel consisted of collagen and heparin (Hep-col) to mimic an in vivo-like environment. The Hep-col gel could immobilize growth factors, which is important for ECM functions. Neural stem/progenitor cells cultured in the Hep-col gel grew and differentiated more actively than in collagen, indicating an in vivo-like environment in the Hep-col gel. Second, a thin-layered gel culture system was developed to realize in situ evaluation of the gel-embedded cells. Cells in a 200-μm-thick gel could be evaluated clearly by a phase-contrast microscope and immunofluorescence staining through reduced optical and diffusional effects. Finally, we found that the neural cells cultured in this system had synaptic connections and neuronal action potentials by immunofluorescence staining and Ca 2+ imaging. In conclusion, this culture method may be a valuable evaluation system for neurotoxicity testing. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. The Future of Animals, Cells, Models, and Systems in Research, Development, Education, and Testing: Proceedings of a Symposium.

    Science.gov (United States)

    National Academy of Sciences - National Research Council, Washington, DC. Inst. of Lab. Animal Resources.

    This volume contains the prepared papers and discussions of a National Academy of Sciences - National Research Council Symposium on the Future of Animals, Cells, Models, and Systems in Research, Development, Education, and Testing. The purpose of the symposium was to examine the past, present, and future contributions of animals to human health…

  18. Dynamic fuzzy cognitive network approach for modelling and control of PEM fuel cell for power electric bicycle system

    International Nuclear Information System (INIS)

    Kheirandish, Azadeh; Motlagh, Farid; Shafiabady, Niusha; Dahari, Mahidzal; Khairi Abdul Wahab, Ahmad

    2017-01-01

    Highlights: •Fuzzy cognitive map was proposed for the first time to describe the behaviour of fuel cell electric bicycle system. •Fuzzy rules were applied to explain the cause and effect between concepts. •To predict and analyse the cognitive map involved in the negotiation process. -- Abstract: Modelling Proton Exchange Membrane Fuel Cell (PEMFC) is the fundamental step in designing efficient systems for achieving higher performance. Among the development of new energy technologies, modelling and optimization of energy processes with pollution reduction, sufficient efficiency and low emission are considered one of the most promising areas of study. Despite affecting factors in PEMFC functionality, providing a reliable model for PEMFC is the key of performance optimization challenge. In this paper, fuzzy cognitive map has been used for modelling PEMFC system that is directed to provide a dynamic cognitive map from the affecting factors of the system. Controlling and modification of the system performance in various conditions is more practical by correlations among the performance factors of the PEMFC derived from fuzzy cognitive maps. On the other hand, the information of fuzzy cognitive map modelling is applicable for modification of neural networks structure for providing more accurate results based on the extracted knowledge from the cognitive map and visualization of the system’s performance. Finally, a rule based fuzzy cognitive map has been used that can be implemented for decision-making to control the system. This rule-based approach provides interpretability while enhancing the performance of the overall system.

  19. Developing a Model Using Homer for a Hybrid Hydrogen Fuel Cell System

    Directory of Open Access Journals (Sweden)

    Fera Annisa

    2013-04-01

    Full Text Available ABSTRACT. Hydrogen is widely considered be the fuel of the near future. Combined wind/PV energy hybrid systems can be used to sources energy to hydrogen production. This paper describes design, simulation and feasibility study of a hybrid energy system for a household in Malaysia. One year recorded wind speed and solar radiation are used for the design of a hybrid energy system. In 2000 was average annual wind speed in Johor Bahru is 3.76 m/s and annual average solar energy resource available is 5.08 kWh/m2/day. National Renewable Energy Laboratory’s HOMER software was used to select an optimum hybrid energy system. In the optimization process, HOMER simulates every system configuration in the search space and displays the feasible ones in a table, sorted by total net present cost (TNPC. The optimization study indicates that sensitivity analysis of the HOMER is shown in the overall winner which shows that the most least cost and optimize hybrid system is combination of 10 kW of PV array, 1 unit of wind turbine, 2 kW of fuel cell, 120 units of batteries and 6 kW converter as well as 1 kW of electrolyzer so as to generate the minimum COE, $2.423 kWh- 1. Although renewable sources (wind and PV involved in the power generation, 1 kg of hydrogen was produced in this system. Pengembangan Model Dengan Menggunakan Homer Untuk Sistem Sel Berbahan bakar Hidrogen Hibrida ABSTRAK. Hidrogen secara luas dianggap sebagai bahan bakar masa depan. Gabungan sistem hibrida energi angin/fotovoltaik dapat digunakan untuk sumber energi produksi hidrogen. Makalah ini menjelaskan desain, simulasi dan studi kelayakan dari sistem energi hibrida untuk rumah tangga di Malaysia. Satu tahun kecepatan angin tercatat dan radiasi matahari digunakan untuk desain sistem energi hibrida. Pada tahun 2000 adalah kecepatan angin rata-rata tahunan di Johor Bahru 3.76 m/det dan rata-rata sumber daya energi surya tahunan yang tersedia adalah 5.08 kWjam/m2/ hari. Software HOMER digunakan

  20. Asymptotic analysis and optimal control of an integro-differential system modelling healthy and cancer cells exposed to chemotherapy

    KAUST Repository

    Pouchol, Camille

    2017-10-27

    We consider a system of two coupled integro-differential equations modelling populations of healthy and cancer cells under chemotherapy. Both populations are structured by a phenotypic variable, representing their level of resistance to the treatment. We analyse the asymptotic behaviour of the model under constant infusion of drugs. By designing an appropriate Lyapunov function, we prove that both cell densities converge to Dirac masses. We then define an optimal control problem, by considering all possible infusion protocols and minimising the number of cancer cells over a prescribed time frame. We provide a quasi-optimal strategy and prove that it solves this problem for large final times. For this modelling framework, we illustrate our results with numerical simulations, and compare our optimal strategy with periodic treatment schedules.

  1. Oxidative stress and age-related changes in T cells: is thalassemia a model of accelerated immune system aging?

    Science.gov (United States)

    Ghatreh-Samani, Mahdi; Esmaeili, Nafiseh; Soleimani, Masoud; Asadi-Samani, Majid; Ghatreh-Samani, Keihan; Shirzad, Hedayatolah

    2016-01-01

    Iron overload in β-thalassemia major occurs mainly due to blood transfusion, an essential treatment for β-thalassemia major patients, which results in oxidative stress. It has been thought that oxidative stress causes elevation of immune system senescent cells. Under this condition, cells normally enhance in aging, which is referred to as premature immunosenescence. Because there is no animal model for immunosenescence, most knowledge on the immunosenescence pattern is based on induction of immunosenescence. In this review, we describe iron overload and oxidative stress in β-thalassemia major patients and how they make these patients a suitable human model for immunosenescence. We also consider oxidative stress in some kinds of chronic virus infections, which induce changes in the immune system similar to β-thalassemia major. In conclusion, a therapeutic approach used to improve the immune system in such chronic virus diseases, may change the immunosenescence state and make life conditions better for β-thalassemia major patients.

  2. Modeling and Design of Hybrid PEM Fuel Cell Systems for Lift Trucks

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham

    driven lift trucks are being used more and more in different companies to reduce their emissions. However, battery driven lift trucks need a long time to recharge and thus may be out of work for a long time. Fuel cell driven lift trucks diminish this problem and are therefore getting more attention...... in a fork-lift truck. In order for the ejector to operate in the largest possible range of load, different approaches (with fixed nozzle and variable nozzle ejectors) have been investigated. Different geometries have been studied in order to optimize the ejector. The optimization is carried out not only...... a virtual fork-lift system. This investigation examines important performance metrics, such as hydrogen consumption and battery SOC as a function of the fuel cell and battery size, control strategy, drive cycle, and load variation for a fork-lift truck system. This study can be used as a benchmark...

  3. Dynamic model of a micro-tubular solid oxide fuel cell stack including an integrated cooling system

    Science.gov (United States)

    Hering, Martin; Brouwer, Jacob; Winkler, Wolfgang

    2017-02-01

    A novel dynamic micro-tubular solid oxide fuel cell (MT-SOFC) and stack model including an integrated cooling system is developed using a quasi three-dimensional, spatially resolved, transient thermodynamic, physical and electrochemical model that accounts for the complex geometrical relations between the cells and cooling-tubes. The modeling approach includes a simplified tubular geometry and stack design including an integrated cooling structure, detailed pressure drop and gas property calculations, the electrical and physical constraints of the stack design that determine the current, as well as control strategies for the temperature. Moreover, an advanced heat transfer balance with detailed radiative heat transfer between the cells and the integrated cooling-tubes, convective heat transfer between the gas flows and the surrounding structures and conductive heat transfer between the solid structures inside of the stack, is included. The detailed model can be used as a design basis for the novel MT-SOFC stack assembly including an integrated cooling system, as well as for the development of a dynamic system control strategy. The evaluated best-case design achieves very high electrical efficiency between around 75 and 55% in the entire power density range between 50 and 550 mW /cm2 due to the novel stack design comprising an integrated cooling structure.

  4. Radiobilogical cell survival models

    International Nuclear Information System (INIS)

    Zackrisson, B.

    1992-01-01

    A central issue in clinical radiobiological research is the prediction of responses to different radiation qualities. The choice of cell survival and dose-response model greatly influences the results. In this context the relationship between theory and model is emphasized. Generally, the interpretations of experimental data depend on the model. Cell survival models are systematized with respect to their relations to radiobiological theories of cell kill. The growing knowlegde of biological, physical, and chemical mechanisms is reflected in the formulation of new models. The present overview shows that recent modelling has been more oriented towards the stochastic fluctuations connected to radiation energy deposition. This implies that the traditional cell surivival models ought to be complemented by models of stochastic energy deposition processes and repair processes at the intracellular level. (orig.)

  5. Process modeling of a reversible solid oxide cell (r-SOC) energy storage system utilizing commercially available SOC reactor

    International Nuclear Information System (INIS)

    Mottaghizadeh, Pegah; Santhanam, Srikanth; Heddrich, Marc P.; Friedrich, K. Andreas; Rinaldi, Fabio

    2017-01-01

    Highlights: • An electric energy storage system was developed based on a commercially available SOC reactor. • Heat generated in SOFC mode of r-SOC is utilized in SOEC operation of r-SOC using latent heat storage. • A round trip efficiency of 54.3% was reached for the reference system at atmospheric pressure. • An improved process system design achieved a round-trip efficiency of 60.4% at 25 bar. - Abstract: The increase of intermittent renewable energy contribution in power grids has urged us to seek means for temporal decoupling of electricity production and consumption. A reversible solid oxide cell (r-SOC) enables storage of surplus electricity through electrochemical reactions when it is in electrolysis mode. The reserved energy in form of chemical compounds is then converted to electricity when the cell operates as a fuel cell. A process system model was implemented using Aspen Plus® V8.8 based on a commercially available r-SOC reactor experimentally characterized at DLR. In this study a complete self-sustaining system configuration is designed by optimal thermal integration and balance of plant. Under reference conditions a round trip efficiency of 54.3% was achieved. Generated heat in fuel cell mode is exploited by latent heat storage tanks to enable endothermic operation of reactor in its electrolysis mode. In total, out of 100 units of thermal energy stored in heat storage tanks during fuel cell mode, 90% was utilized to offset heat demand of system in its electrolysis mode. Parametric analysis revealed the significance of heat storage tanks in thermal management even when reactor entered its exothermic mode of electrolysis. An improved process system design demonstrates a system round-trip efficiency of 60.4% at 25 bar.

  6. Hydrodynamic model of cells for designing systems of urban groundwater drainage

    Science.gov (United States)

    Zimmermann, Eric; Riccardi, Gerardo

    2000-08-01

    An improved mathematical hydrodynamic quasi-two-dimensional model of cells, CELSUB3, is presented for simulating drainage systems that consist of pumping well fields or subsurface drains. The CELSUB3 model is composed of an assemblage of algorithms that have been developed and tested previously and that simulate saturated flow in porous media, closed conduit flow, and flow through pumping stations. A new type of link between aquifer cells and drainage conduits is proposed. This link is verified in simple problems with well known analytical solutions. The correlation between results from analytical and mathematical solutions was considered satisfactory in all cases. To simulate more complex situations, the new proposed version, CELSUB3, was applied in a project designed to control the water-table level within a sewer system in Chañar Ladeado Town, Santa Fe Province, Argentina. Alternative drainage designs, which were evaluated under conditions of dynamic recharge caused by rainfall in a critical year (wettest year for the period of record) and a typical year, are briefly described. After analyzing ten alternative designs, the best technical-economic solution is a subsurface drainage system of closed conduits with pumping stations and evacuation channels. Résumé. Un modèle hydrodynamique perfectionné de cellules en quasi 2D, CELSUB3, est présenté dans le but de simuler des systèmes de drainage qui consistent en des champs de puits de pompage ou de drains souterrains. Le modèle CELSUB3 est composé d'un assemblage d'algorithmes développés et testés précédemment et qui simulent des écoulements en milieu poreux saturé, en conduites et dans des stations de pompage. Un nouveau type de lien entre des cellules d'aquifères et des drains est proposé. Ce lien est vérifié dans des problèmes simples dont les solutions analytiques sont bien connues. La corrélation entre les résultats des solutions analytiques et des solutions mathématiques a été consid

  7. CPV cells cooling system based on submerged jet impingement: CFD modeling and experimental validation

    Science.gov (United States)

    Montorfano, Davide; Gaetano, Antonio; Barbato, Maurizio C.; Ambrosetti, Gianluca; Pedretti, Andrea

    2014-09-01

    Concentrating photovoltaic (CPV) cells offer higher efficiencies with regard to the PV ones and allow to strongly reduce the overall solar cell area. However, to operate correctly and exploit their advantages, their temperature has to be kept low and as uniform as possible and the cooling circuit pressure drops need to be limited. In this work an impingement water jet cooling system specifically designed for an industrial HCPV receiver is studied. Through the literature and by means of accurate computational fluid dynamics (CFD) simulations, the nozzle to plate distance, the number of jets and the nozzle pitch, i.e. the distance between adjacent jets, were optimized. Afterwards, extensive experimental tests were performed to validate pressure drops and cooling power simulation results.

  8. IMMORTALIZED MICROGLIAL CELLS AS A MODEL SYSTEM FOR OXIDATIVE STRESS: PESTICIDE-INDUCED GENOMIC GHANGES.

    Science.gov (United States)

    In risk assessment there is a need to accelerate toxicological evaluation of vast numbers of chemicals. New programs focus on identifying common modes of action and on model systems for rapid screening. In this study we address both these issues. Oxidative stress is a good can...

  9. Modeling cellular systems

    CERN Document Server

    Matthäus, Franziska; Pahle, Jürgen

    2017-01-01

    This contributed volume comprises research articles and reviews on topics connected to the mathematical modeling of cellular systems. These contributions cover signaling pathways, stochastic effects, cell motility and mechanics, pattern formation processes, as well as multi-scale approaches. All authors attended the workshop on "Modeling Cellular Systems" which took place in Heidelberg in October 2014. The target audience primarily comprises researchers and experts in the field, but the book may also be beneficial for graduate students.

  10. Anaerobic co-culture of mesenchymal stem cells and anaerobic pathogens - a new in vitro model system.

    Directory of Open Access Journals (Sweden)

    Katja Kriebel

    Full Text Available BACKGROUND: Human mesenchymal stem cells (hMSCs are multipotent by nature and are originally isolated from bone marrow. In light of a future application of hMSCs in the oral cavity, a body compartment with varying oxygen partial pressures and an omnipresence of different bacterial species i.e. periodontitis pathogens, we performed this study to gain information about the behavior of hMSC in an anaerobic system and the response in interaction with oral bacterial pathogens. METHODOLOGY/PRINCIPAL FINDINGS: We established a model system with oral pathogenic bacterial species and eukaryotic cells cultured in anaerobic conditions. The facultative anaerobe bacteria Fusobacterium nucleatum, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were studied. Their effects on hMSCs and primary as well as permanent gingival epithelial cells (Ca9-22, HGPEC were comparatively analyzed. We show that hMSCs cope with anoxic conditions, since 40% vital cells remain after 72 h of anaerobic culture. The Ca9-22 and HGPEC cells are significantly more sensitive to lack of oxygen. All bacterial species reveal a comparatively low adherence to and internalization into hMSCs (0.2% and 0.01% of the initial inoculum, respectively. In comparison, the Ca9-22 and HGPEC cells present better targets for bacterial adherence and internalization. The production of the pro-inflammatory chemokine IL-8 is higher in both gingival epithelial cell lines compared to hMSCs and Fusobacterium nucleatum induce a time-dependent cytokine secretion in both cell lines. Porphyromonas gingivalis is less effective in stimulating secretion of IL-8 in the co-cultivation experiments. CONCLUSIONS/SIGNIFICANCE: HMSCs are suitable for use in anoxic regions of the oral cavity. The interaction with local pathogenic bacteria does not result in massive pro-inflammatory cytokine responses. The test system established in this study allowed further investigation of parameters prior to set up of

  11. Graph Cellular Automata with Relation-Based Neighbourhoods of Cells for Complex Systems Modelling: A Case of Traffic Simulation

    Directory of Open Access Journals (Sweden)

    Krzysztof Małecki

    2017-12-01

    Full Text Available A complex system is a set of mutually interacting elements for which it is possible to construct a mathematical model. This article focuses on the cellular automata theory and the graph theory in order to compare various types of cellular automata and to analyse applications of graph structures together with cellular automata. It proposes a graph cellular automaton with a variable configuration of cells and relation-based neighbourhoods (r–GCA. The developed mechanism enables modelling of phenomena found in complex systems (e.g., transport networks, urban logistics, social networks taking into account the interaction between the existing objects. As an implementation example, modelling of moving vehicles has been made and r–GCA was compared to the other cellular automata models simulating the road traffic and used in the computer simulation process.

  12. The modeling and simulation of thermal based modified solid oxide fuel cell (SOFC for grid-connected systems

    Directory of Open Access Journals (Sweden)

    Ayetül Gelen

    2015-05-01

    Full Text Available This paper presents a thermal based modified dynamic model of a Solid Oxide Fuel Cell (SOFC for grid-connected systems. The proposed fuel cell model involves ohmic, activation and concentration voltage losses, thermal dynamics, methanol reformer, fuel utilization factor and power limiting module. A power conditioning unit (PCU, which consists of a DC-DC boost converter and a DC-AC voltage-source inverter (VSI, their controller, transformer and filter, is designed for grid-connected systems. The voltage-source inverter with six Insulated Gate Bipolar Transistor (IGBT switches inverts the DC voltage that comes from the converter into a sinusoidal voltage synchronized with the grid. The simulations and modeling of the system are developed on Matlab/Simulink environment. The performance of SOFC with converter is examined under step and random load conditions. The simulation results show that the designed boost converter for the proposed thermal based modified SOFC model has fairly followed different DC load variations. Finally, the AC bus of 400 Volt and 50 Hz is connected to a single-machine infinite bus (SMIB through a transmission line. The real and reactive power managements of the inverter are analyzed by an infinite bus system. Thus, the desired nominal values are properly obtained by means of the inverter controller.

  13. Modulating and modeling aggregation of cell-seeded microcarriers in stirred culture system for macrotissue engineering.

    Science.gov (United States)

    Mei, Yang; Luo, Houyong; Tang, Qiang; Ye, Zhaoyang; Zhou, Yan; Tan, Wen-Song

    2010-11-01

    A recently developed protocol, "microtissue assembly" holds great promise to address the issue of limited mass transfer within engineered large tissue replacements (macrotissues), wherein small "building blocks" (microtissues) are prepared and then assembled into macrotissues. Previous studies suggested that aggregation behavior of microcarrier-based microtissues were very important for macrotissue engineering. However, a systematic study on the aggregation behavior of microtissues is still missing. In this study, to examine the aggregation behavior of microtissues, effects of key operation parameters in dynamic culture including cell seeding density, microcarrier concentration, L-ascorbic acid 2-phosphate (V(c)) and agitating speed were investigated. The aggregation process could be divided into three phases (i.e., lag, growth and stable). Aggregation efficiency (S) was found to be modulated by cell seeding density, microcarrier concentration, addition of V(c) and agitating speed. A mathematical model correlating the operation parameters with S at different phases of aggregation was developed and experimentally proved to be able to predict S with varied operation parameters. In the end, a cylindrical macrotissue (diameter × height: 2.0 cm × 0.8 cm) with fairly good integrity and cellularity and uniform cell distribution was successfully engineered through perfusion assembling microtissues with controlled S under selected culture conditions. Our study showed that aggregation of microtissues could be precisely modulated, which would definitely facilitate engineering macrotissues with high quality. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Caenorhabditis elegans as a model system for studying non-cell-autonomous mechanisms in protein-misfolding diseases

    Directory of Open Access Journals (Sweden)

    Carmen I. Nussbaum-Krammer

    2014-01-01

    Full Text Available Caenorhabditis elegans has a number of distinct advantages that are useful for understanding the basis for cellular and organismal dysfunction underlying age-associated diseases of protein misfolding. Although protein aggregation, a key feature of human neurodegenerative diseases, has been typically explored in vivo at the single-cell level using cells in culture, there is now increasing evidence that proteotoxicity has a non-cell-autonomous component and is communicated between cells and tissues in a multicellular organism. These discoveries have opened up new avenues for the use of C. elegans as an ideal animal model system to study non-cell-autonomous proteotoxicity, prion-like propagation of aggregation-prone proteins, and the organismal regulation of stress responses and proteostasis. This Review focuses on recent evidence that C. elegans has mechanisms to transmit certain classes of toxic proteins between tissues and a complex stress response that integrates and coordinates signals from single cells and tissues across the organism. These findings emphasize the potential of C. elegans to provide insights into non-cell-autonomous proteotoxic mechanisms underlying age-related protein-misfolding diseases.

  15. System modeling for the advanced thermionic initiative single cell thermionic space nuclear reactor

    International Nuclear Information System (INIS)

    Lee, H.H.; Lewis, B.R.; Klein, A.C.; Pawlowski, R.A.

    1993-01-01

    Incore thermionic space reactor design concepts which operate in a nominal power output range of 20 to 40 kWe are described. Details of the neutronics, thermionic, shielding, and heat rejection performance are presented. Two different designs, ATI-Driven and ATI-Driverless, are considered. Comparison of the core overall performance of these two configurations are described. The comparison of these two cores includes the overall conversion efficiency, reactor mass, shield mass, and heat rejection mass. An overall system design has been developed to model the advanced incore thermionic energy conversion based nuclear reactor systems for space applications in this power range

  16. Models for mature T-cell lymphomas--a critical appraisal of experimental systems and their contribution to current T-cell tumorigenic concepts.

    Science.gov (United States)

    Warner, Kathrin; Crispatzu, Giuliano; Al-Ghaili, Nabil; Weit, Nicole; Florou, Vaia; You, M James; Newrzela, Sebastian; Herling, Marco

    2013-12-01

    Mature T-cell lymphomas/leukemias (MTCL) have been understudied lymphoid neoplasms that currently receive growing attention. Our historically rudimentary molecular understanding and dissatisfactory interventional success in this complex and for the most part poor-prognostic group of tumors is only slightly improving. A major limiting aspect in further progress in these rare neoplasms is the lack of suitable model systems that would substantially facilitate pathogenic studies and pre-clinical drug evaluations. Such representations of MTCL have thus far not been systematically appraised. We therefore provide an overview on existing models and point out their particular advantages and limitations in the context of the specific scientific questions. After addressing issues of species-specific differences and classifications, we summarize data on MTCL cell lines of human as well as murine origin, on murine strain predispositions to MTCL, on available models of genetically engineered mice, and on transplant systems. From an in-silico meta-analysis of available primary data of gene expression profiles on human MTCL we cross-reference genes reported to transform T-cells in mice and reflect on their general vs entity-restricted relevance and on target-promoter influences. Overall, we identify the urgent need for new models of higher fidelity to human MTCL with respect to their increasingly recognized diversity and to predictions of drug response. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  17. High-fidelity stack and system modeling for tubular solid oxide fuel cell system design and thermal management

    Science.gov (United States)

    Kattke, K. J.; Braun, R. J.; Colclasure, A. M.; Goldin, G.

    Effective thermal integration of system components is critical to the performance of small-scale (design and simulation tool for a highly-integrated tubular SOFC system. The SOFC is modeled using a high fidelity, one-dimensional tube model coupled to a three-dimensional computational fluid dynamics (CFD) model. Recuperative heat exchange between SOFC tail-gas and inlet cathode air and reformer air/fuel preheat processes are captured within the CFD model. Quasi one-dimensional thermal resistance models of the tail-gas combustor (TGC) and catalytic partial oxidation (CPOx) complete the balance of plant (BoP) and SOFC coupling. The simulation tool is demonstrated on a prototype 66-tube SOFC system with 650 W of nominal gross power. Stack cooling predominately occurs at the external surface of the tubes where radiation accounts for 66-92% of heat transfer. A strong relationship develops between the power output of a tube and its view factor to the relatively cold cylinder wall surrounding the bundle. The bundle geometry yields seven view factor groupings which correspond to seven power groupings with tube powers ranging from 7.6-10.8 W. Furthermore, the low effectiveness of the co-flow recuperator contributes to lower tube powers at the bundle outer periphery.

  18. Multiple Model Predictive Hybrid Feedforward Control of Fuel Cell Power Generation System

    Directory of Open Access Journals (Sweden)

    Long Wu

    2018-02-01

    Full Text Available Solid oxide fuel cell (SOFC is widely considered as an alternative solution among the family of the sustainable distributed generation. Its load flexibility enables it adjusting the power output to meet the requirements from power grid balance. Although promising, its control is challenging when faced with load changes, during which the output voltage is required to be maintained as constant and fuel utilization rate kept within a safe range. Moreover, it makes the control even more intractable because of the multivariable coupling and strong nonlinearity within the wide-range operating conditions. To this end, this paper developed a multiple model predictive control strategy for reliable SOFC operation. The resistance load is regarded as a measurable disturbance, which is an input to the model predictive control as feedforward compensation. The coupling is accommodated by the receding horizon optimization. The nonlinearity is mitigated by the multiple linear models, the weighted sum of which serves as the final control execution. The merits of the proposed control structure are demonstrated by the simulation results.

  19. Hybrid Microgrid Model based on Solar Photovoltaics with Batteries and Fuel Cells system for intermittent applications

    Science.gov (United States)

    Patterson, Maxx

    Microgrids are a subset of the modern power structure; using distributed generation (DG) to supply power to communities rather than vast regions. The reduced scale mitigates loss allowing the power produced to do more with better control, giving greater security, reliability, and design flexibility. This paper explores the performance and cost viability of a hybrid grid-tied microgrid that utilizes Photovoltaic (PV), batteries, and fuel cell (FC) technology. The concept proposes that each community home is equipped with more PV than is required for normal operation. As the homes are part of a microgrid, excess or unused energy from one home is collected for use elsewhere within the microgrid footprint. The surplus power that would have been discarded becomes a community asset, and is used to run intermittent services. In this paper, the modeled community does not have parking adjacent to each home allowing for the installment of a privately owned slower Level 2 charger, making EV ownership option untenable. A solution is to provide a Level 3 DC Quick Charger (DCQC) as the intermittent service. The addition of batteries and Fuel Cells are meant to increase load leveling, reliability, and instill limited island capability.

  20. Physical models of cell motility

    CERN Document Server

    2016-01-01

    This book surveys the most recent advances in physics-inspired cell movement models. This synergetic, cross-disciplinary effort to increase the fidelity of computational algorithms will lead to a better understanding of the complex biomechanics of cell movement, and stimulate progress in research on related active matter systems, from suspensions of bacteria and synthetic swimmers to cell tissues and cytoskeleton.Cell motility and collective motion are among the most important themes in biology and statistical physics of out-of-equilibrium systems, and crucial for morphogenesis, wound healing, and immune response in eukaryotic organisms. It is also relevant for the development of effective treatment strategies for diseases such as cancer, and for the design of bioactive surfaces for cell sorting and manipulation. Substrate-based cell motility is, however, a very complex process as regulatory pathways and physical force generation mechanisms are intertwined. To understand the interplay between adhesion, force ...

  1. Performance improvement of a battery/PV/fuel cell/grid hybrid energy system considering load uncertainty modeling using IGDT

    International Nuclear Information System (INIS)

    Nojavan, Sayyad; Majidi, Majid; Zare, Kazem

    2017-01-01

    Highlights: • Optimum performance of PV/battery/fuel cell/grid hybrid system under load uncertainty. • Employing information gap decision theory (IGDT) to model the load uncertainty. • Robustness and opportunity functions of IGDT are modeled for risk-averse and risk-taker. • Robust strategy of hybrid system's operation obtained from robustness function. • Opportunistic strategy of hybrid system's operation obtained from opportunity function. - Abstract: Nowadays with the speed that electrical loads are growing, system operators are challenged to manage the sources they use to supply loads which means that that besides upstream grid as the main sources of electric power, they can utilize renewable and non-renewable energy sources to meet the energy demand. In the proposed paper, a photovoltaic (PV)/fuel cell/battery hybrid system along with upstream grid has been utilized to supply two different types of loads: electrical load and thermal load. Operators should have to consider load uncertainty to manage the strategies they employ to supply load. In other words, operators have to evaluate how load variation would affect their energy procurement strategies. Therefore, information gap decision theory (IGDT) technique has been proposed to model the uncertainty of electrical load. Utilizing IGDT approach, robustness and opportunity functions are achieved which can be used by system operator to take the appropriate strategy. The uncertainty modeling of load enables operator to make appropriate decisions to optimize the system’s operation against possible changes in load. A case study has been simulated to validate the effects of proposed technique.

  2. Glial origin of mesenchymal stem cells in a tooth model system

    NARCIS (Netherlands)

    Kaukua, Nina; Shahidi, Maryam Khatibi; Konstantinidou, Chrysoula; Dyachuk, Vyacheslav; Kaucka, Marketa; Furlan, Alessandro; An, Zhengwen; Wang, Longlong; Hultman, Isabell; Ahrlund-Richter, Lars; Blom, Hans; Brismar, Hjalmar; Lopes, Natalia Assaife; Pachnis, Vassilis; Suter, Ueli; Clevers, Hans; Thesleff, Irma; Sharpe, Paul; Ernfors, Patrik; Fried, Kaj; Adameyko, Igor

    2014-01-01

    Mesenchymal stem cells occupy niches in stromal tissues where they provide sources of cells for specialized mesenchymal derivatives during growth and repair. The origins of mesenchymal stem cells have been the subject of considerable discussion, and current consensus holds that perivascular cells

  3. A system identification approach for developing model predictive controllers of antibody quality attributes in cell culture processes.

    Science.gov (United States)

    Downey, Brandon; Schmitt, John; Beller, Justin; Russell, Brian; Quach, Anthony; Hermann, Elizabeth; Lyon, David; Breit, Jeffrey

    2017-11-01

    As the biopharmaceutical industry evolves to include more diverse protein formats and processes, more robust control of Critical Quality Attributes (CQAs) is needed to maintain processing flexibility without compromising quality. Active control of CQAs has been demonstrated using model predictive control techniques, which allow development of processes which are robust against disturbances associated with raw material variability and other potentially flexible operating conditions. Wide adoption of model predictive control in biopharmaceutical cell culture processes has been hampered, however, in part due to the large amount of data and expertise required to make a predictive model of controlled CQAs, a requirement for model predictive control. Here we developed a highly automated, perfusion apparatus to systematically and efficiently generate predictive models using application of system identification approaches. We successfully created a predictive model of %galactosylation using data obtained by manipulating galactose concentration in the perfusion apparatus in serialized step change experiments. We then demonstrated the use of the model in a model predictive controller in a simulated control scenario to successfully achieve a %galactosylation set point in a simulated fed-batch culture. The automated model identification approach demonstrated here can potentially be generalized to many CQAs, and could be a more efficient, faster, and highly automated alternative to batch experiments for developing predictive models in cell culture processes, and allow the wider adoption of model predictive control in biopharmaceutical processes. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 33:1647-1661, 2017. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

  4. Stochastic modeling indicates that aging and somatic evolution in the hematopoetic system are driven by non-cell-autonomous processes.

    Science.gov (United States)

    Rozhok, Andrii I; Salstrom, Jennifer L; DeGregori, James

    2014-12-01

    Age-dependent tissue decline and increased cancer incidence are widely accepted to be rate-limited by the accumulation of somatic mutations over time. Current models of carcinogenesis are dominated by the assumption that oncogenic mutations have defined advantageous fitness effects on recipient stem and progenitor cells, promoting and rate-limiting somatic evolution. However, this assumption is markedly discrepant with evolutionary theory, whereby fitness is a dynamic property of a phenotype imposed upon and widely modulated by environment. We computationally modeled dynamic microenvironment-dependent fitness alterations in hematopoietic stem cells (HSC) within the Sprengel-Liebig system known to govern evolution at the population level. Our model for the first time integrates real data on age-dependent dynamics of HSC division rates, pool size, and accumulation of genetic changes and demonstrates that somatic evolution is not rate-limited by the occurrence of mutations, but instead results from aged microenvironment-driven alterations in the selective/fitness value of previously accumulated genetic changes. Our results are also consistent with evolutionary models of aging and thus oppose both somatic mutation-centric paradigms of carcinogenesis and tissue functional decline. In total, we demonstrate that aging directly promotes HSC fitness decline and somatic evolution via non-cell-autonomous mechanisms.

  5. Symposium on Electrochemical and Thermal Modeling of Battery, Fuel Cell, and Photoenergy Conversion Systems, San Diego, CA, Oct. 20-22, 1986, Proceedings

    Science.gov (United States)

    Selman, J. Robert; Maru, Hans C.

    Papers are presented on modeling of the zinc chlorine battery, design modeling of zinc/bromine battery systems, the modeling of aluminum-air battery systems, and a point defect model for a nickel electrode structure. Also considered are the impedance of a tubular electrode under laminar flow, mathematical modeling of a LiAl/Cl2 cell with a gas diffusion Cl2 electrode, ultrahigh power batteries, and battery thermal modeling. Other topics include an Na/beta-alumina/NaAlCl4, Cl2/C circulating cell, leakage currents in electrochemical systems having common electrodes, modeling for CO poisoning of a fuel cell anode, electrochemical corrosion of carbonaceous materials, and electrolyte management in molten carbonate fuel cells.

  6. Systemic Mesenchymal Stromal Cell Transplantation Prevents Functional Bone Loss in a Mouse Model of Age-Related Osteoporosis.

    Science.gov (United States)

    Kiernan, Jeffrey; Hu, Sally; Grynpas, Marc D; Davies, John E; Stanford, William L

    2016-05-01

    Age-related osteoporosis is driven by defects in the tissue-resident mesenchymal stromal cells (MSCs), a heterogeneous population of musculoskeletal progenitors that includes skeletal stem cells. MSC decline leads to reduced bone formation, causing loss of bone volume and the breakdown of bony microarchitecture crucial to trabecular strength. Furthermore, the low-turnover state precipitated by MSC loss leads to low-quality bone that is unable to perform remodeling-mediated maintenance--replacing old damaged bone with new healthy tissue. Using minimally expanded exogenous MSCs injected systemically into a mouse model of human age-related osteoporosis, we show long-term engraftment and markedly increased bone formation. This led to improved bone quality and turnover and, importantly, sustained microarchitectural competence. These data establish proof of concept that MSC transplantation may be used to prevent or treat human age-related osteoporosis. This study shows that a single dose of minimally expanded mesenchymal stromal cells (MSCs) injected systemically into a mouse model of human age-related osteoporosis display long-term engraftment and prevent the decline in bone formation, bone quality, and microarchitectural competence. This work adds to a growing body of evidence suggesting that the decline of MSCs associated with age-related osteoporosis is a major transformative event in the progression of the disease. Furthermore, it establishes proof of concept that MSC transplantation may be a viable therapeutic strategy to treat or prevent human age-related osteoporosis. ©AlphaMed Press.

  7. Fuel cell-based CHP system modelling using Artificial Neural Networks aimed at developing techno-economic efficiency maximization control systems

    International Nuclear Information System (INIS)

    Asensio, F.J.; San Martín, J.I.; Zamora, I.; Garcia-Villalobos, J.

    2017-01-01

    This paper focuses on the modelling of the performance of a Polymer Electrolyte Membrane Fuel Cell (PEMFC)-based cogeneration system to integrate it in hybrid and/or connected to grid systems and enable the optimization of the techno-economic efficiency of the system in which it is integrated. To this end, experimental tests on a PEMFC-based cogeneration system of 600 W of electrical power have been performed to train an Artificial Neural Network (ANN). Once the learning of the ANN, it has been able to emulate real operating conditions, such as the cooling water out temperature and the hydrogen consumption of the PEMFC depending on several variables, such as the electric power demanded, temperature of the inlet water flow to the cooling circuit, cooling water flow and the heat demanded to the CHP system. After analysing the results, it is concluded that the presented model reproduces with enough accuracy and precision the performance of the experimented PEMFC, thus enabling the use of the model and the ANN learning methodology to model other PEMFC-based cogeneration systems and integrate them in techno-economic efficiency optimization control systems. - Highlights: • The effect of the energy demand variation on the PEMFC's efficiency is predicted. • The model relies on experimental data obtained from a 600 W PEMFC. • It provides the temperature and the hydrogen consumption with good accuracy. • The range in which the global energy efficiency could be improved is provided.

  8. Model-based diagnosis through Structural Analysis and Causal Computation for automotive Polymer Electrolyte Membrane Fuel Cell systems

    Science.gov (United States)

    Polverino, Pierpaolo; Frisk, Erik; Jung, Daniel; Krysander, Mattias; Pianese, Cesare

    2017-07-01

    The present paper proposes an advanced approach for Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems fault detection and isolation through a model-based diagnostic algorithm. The considered algorithm is developed upon a lumped parameter model simulating a whole PEMFC system oriented towards automotive applications. This model is inspired by other models available in the literature, with further attention to stack thermal dynamics and water management. The developed model is analysed by means of Structural Analysis, to identify the correlations among involved physical variables, defined equations and a set of faults which may occur in the system (related to both auxiliary components malfunctions and stack degradation phenomena). Residual generators are designed by means of Causal Computation analysis and the maximum theoretical fault isolability, achievable with a minimal number of installed sensors, is investigated. The achieved results proved the capability of the algorithm to theoretically detect and isolate almost all faults with the only use of stack voltage and temperature sensors, with significant advantages from an industrial point of view. The effective fault isolability is proved through fault simulations at a specific fault magnitude with an advanced residual evaluation technique, to consider quantitative residual deviations from normal conditions and achieve univocal fault isolation.

  9. Solar cell concentrating system

    International Nuclear Information System (INIS)

    Garg, H.P.; Sharma, V.K.; Agarwal, R.K.

    1986-11-01

    This study reviews fabrication techniques and testing facilities for different solar cells under concentration which have been developed and tested. It is also aimed to examine solar energy concentrators which are prospective candidates for photovoltaic concentrator systems. This may provide an impetus to the scientists working in the area of solar cell technology

  10. In silico characterization of cell-cell interactions using a cellular automata model of cell culture.

    Science.gov (United States)

    Kihara, Takanori; Kashitani, Kosuke; Miyake, Jun

    2017-07-14

    Cell proliferation is a key characteristic of eukaryotic cells. During cell proliferation, cells interact with each other. In this study, we developed a cellular automata model to estimate cell-cell interactions using experimentally obtained images of cultured cells. We used four types of cells; HeLa cells, human osteosarcoma (HOS) cells, rat mesenchymal stem cells (MSCs), and rat smooth muscle A7r5 cells. These cells were cultured and stained daily. The obtained cell images were binarized and clipped into squares containing about 10 4 cells. These cells showed characteristic cell proliferation patterns. The growth curves of these cells were generated from the cell proliferation images and we determined the doubling time of these cells from the growth curves. We developed a simple cellular automata system with an easily accessible graphical user interface. This system has five variable parameters, namely, initial cell number, doubling time, motility, cell-cell adhesion, and cell-cell contact inhibition (of proliferation). Within these parameters, we obtained initial cell numbers and doubling times experimentally. We set the motility at a constant value because the effect of the parameter for our simulation was restricted. Therefore, we simulated cell proliferation behavior with cell-cell adhesion and cell-cell contact inhibition as variables. By comparing growth curves and proliferation cell images, we succeeded in determining the cell-cell interaction properties of each cell. Simulated HeLa and HOS cells exhibited low cell-cell adhesion and weak cell-cell contact inhibition. Simulated MSCs exhibited high cell-cell adhesion and positive cell-cell contact inhibition. Simulated A7r5 cells exhibited low cell-cell adhesion and strong cell-cell contact inhibition. These simulated results correlated with the experimental growth curves and proliferation images. Our simulation approach is an easy method for evaluating the cell-cell interaction properties of cells.

  11. Nanotechnology convergence and modeling paradigm of sustainable energy system using polymer electrolyte membrane fuel cell as a benchmark example

    International Nuclear Information System (INIS)

    Chung, Pil Seung; So, Dae Sup; Biegler, Lorenz T.; Jhon, Myung S.

    2012-01-01

    Developments in nanotechnology have led to innovative progress and converging technologies in engineering and science. These demand novel methodologies that enable efficient communications from the nanoscale all the way to decision-making criteria for actual production systems. In this paper, we discuss the convergence of nanotechnology and novel multi-scale modeling paradigms by using the fuel cell system as a benchmark example. This approach includes complex multi-phenomena at different time and length scales along with the introduction of an optimization framework for application-driven nanotechnology research trends. The modeling paradigm introduced here covers the novel holistic integration from atomistic/molecular phenomena to meso/continuum scales. System optimization is also discussed with respect to the reduced order parameters for a coarse-graining procedure in multi-scale model integration as well as system design. The development of a hierarchical multi-scale paradigm consolidates the theoretical analysis and enables large-scale decision-making of process level design, based on first-principles, and therefore promotes the convergence of nanotechnology to sustainable energy technologies.

  12. Nanotechnology convergence and modeling paradigm of sustainable energy system using polymer electrolyte membrane fuel cell as a benchmark example

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Pil Seung; So, Dae Sup; Biegler, Lorenz T.; Jhon, Myung S., E-mail: mj3a@andrew.cmu.edu [Carnegie Mellon University, Department of Chemical Engineering (United States)

    2012-08-15

    Developments in nanotechnology have led to innovative progress and converging technologies in engineering and science. These demand novel methodologies that enable efficient communications from the nanoscale all the way to decision-making criteria for actual production systems. In this paper, we discuss the convergence of nanotechnology and novel multi-scale modeling paradigms by using the fuel cell system as a benchmark example. This approach includes complex multi-phenomena at different time and length scales along with the introduction of an optimization framework for application-driven nanotechnology research trends. The modeling paradigm introduced here covers the novel holistic integration from atomistic/molecular phenomena to meso/continuum scales. System optimization is also discussed with respect to the reduced order parameters for a coarse-graining procedure in multi-scale model integration as well as system design. The development of a hierarchical multi-scale paradigm consolidates the theoretical analysis and enables large-scale decision-making of process level design, based on first-principles, and therefore promotes the convergence of nanotechnology to sustainable energy technologies.

  13. Fuel cell systems

    International Nuclear Information System (INIS)

    Kotevski, Darko

    2003-01-01

    Fuel cell systems are an entirely different approach to the production of electricity than traditional technologies. They are similar to the batteries in that both produce direct current through electrochemical process. There are six types of fuel cells each with a different type of electrolyte, but they all share certain important characteristics: high electrical efficiency, low environmental impact and fuel flexibility. Fuel cells serve a variety of applications: stationary power plants, transport vehicles and portable power. That is why world wide efforts are addressed to improvement of this technology. (Original)

  14. Intratracheal Administration of Mesenchymal Stem Cells Modulates Tachykinin System, Suppresses Airway Remodeling and Reduces Airway Hyperresponsiveness in an Animal Model.

    Directory of Open Access Journals (Sweden)

    Konrad Urbanek

    Full Text Available The need for new options for chronic lung diseases promotes the research on stem cells for lung repair. Bone marrow-derived mesenchymal stem cells (MSCs can modulate lung inflammation, but the data on cellular processes involved in early airway remodeling and the potential involvement of neuropeptides are scarce.To elucidate the mechanisms by which local administration of MSCs interferes with pathophysiological features of airway hyperresponsiveness in an animal model.GFP-tagged mouse MSCs were intratracheally delivered in the ovalbumin mouse model with subsequent functional tests, the analysis of cytokine levels, neuropeptide expression and histological evaluation of MSCs fate and airway pathology. Additionally, MSCs were exposed to pro-inflammatory factors in vitro.Functional improvement was observed after MSC administration. Although MSCs did not adopt lung cell phenotypes, cell therapy positively affected airway remodeling reducing the hyperplastic phase of the gain in bronchial smooth muscle mass, decreasing the proliferation of epithelium in which mucus metaplasia was also lowered. Decrease of interleukin-4, interleukin-5, interleukin-13 and increase of interleukin-10 in bronchoalveolar lavage was also observed. Exposed to pro-inflammatory cytokines, MSCs upregulated indoleamine 2,3-dioxygenase. Moreover, asthma-related in vivo upregulation of pro-inflammatory neurokinin 1 and neurokinin 2 receptors was counteracted by MSCs that also determined a partial restoration of VIP, a neuropeptide with anti-inflammatory properties.Intratracheally administered MSCs positively modulate airway remodeling, reduce inflammation and improve function, demonstrating their ability to promote tissue homeostasis in the course of experimental allergic asthma. Because of a limited tissue retention, the functional impact of MSCs may be attributed to their immunomodulatory response combined with the interference of neuropeptide system activation and tissue

  15. Biomass-powered Solid Oxide Fuel Cells : Experimental and Modeling Studies for System Integrations

    NARCIS (Netherlands)

    Liu, M.

    2013-01-01

    Biomass is a sustainable energy source which, through thermo-chemical processes of biomass gasification, is able to be converted from a solid biomass fuel into a gas mixture, known as syngas or biosyngas. A solid oxide fuel cell (SOFC) is a power generation device that directly converts the chemical

  16. Defective pulmonary innate immune responses post-stem cell transplantation; review and results from one model system

    Directory of Open Access Journals (Sweden)

    Racquel eDomingo-Gonzalez

    2013-05-01

    Full Text Available Infectious pulmonary complications limit the success of hematopoietic stem cell transplantation (HSCT as a therapy for malignant and nonmalignant disorders. Susceptibility to pathogens in both autologous and allogeneic HSCT recipients persists despite successful immune reconstitution. As studying the causal effects of these immune defects in the human population can be limiting, a bone marrow transplant (BMT mouse model can be used to understand the defect in mounting a productive innate immune response post-transplantation. When syngeneic BMT is performed, this system allows the study of BMT-induced alterations in innate immune cell function that are independent of the confounding effects of immunosuppressive therapy and graft-versus-host disease. Studies from several laboratories, including our own show that pulmonary susceptibility to bacterial infections post-BMT are largely due to alterations in the lung alveolar macrophages. Changes in these cells post-BMT include cytokine and eicosanoid dysregulations, scavenger receptor alterations, changes in micro RNA profiles, and alterations in intracellular signaling molecules that limit bacterial phagocytosis and killing. The changes that occur highlight mechanisms that promote susceptibility to infections commonly afflicting HSCT recipients and provide insight into therapeutic targets that may improve patient outcomes post-HSCT.

  17. Interaction between the immune system and acute myeloid leukemia: A model incorporating promotion of regulatory T cell expansion by leukemic cells.

    Science.gov (United States)

    Nishiyama, Yoshiaki; Saikawa, Yutaka; Nishiyama, Nobuaki

    2018-03-01

    Population dynamics of regulatory T cells (Treg) are crucial for the underlying interplay between leukemic and immune cells in progression of acute myeloid leukemia (AML). The goal of this work is to elucidate the dynamics of a model that includes Treg, which can be qualitatively assessed by accumulating clinical findings on the impact of activated immune cell infusion after selective Treg depletion. We constructed an ordinary differential equation model to describe the dynamics of three components in AML: leukemic blast cells, mature regulatory T cells (Treg), and mature effective T cells (Teff), including cytotoxic T lymphocytes. The model includes promotion of Treg expansion by leukemic blast cells, leukemic stem cell and progenitor cell targeting by Teff, and Treg-mediated Teff suppression, and exhibits two coexisting, stable steady states, corresponding to high leukemic cell load at diagnosis or relapse, and to long-term complete remission. Our model is capable of explaining the clinical findings that the survival of patients with AML after allogeneic stem cell transplantation is influenced by the duration of complete remission, and that cut-off minimal residual disease thresholds associated with a 100% relapse rate are identified in AML. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Modeling and Optimization of Renewable and Hybrid Fuel Cell Systems for Space Power and Propulsion

    Science.gov (United States)

    2010-11-14

    electrolyser (Hogen GC 600) which splits the water molecule into hydrogen and oxygen molecules. The produced hydrogen supplies the fuel cell stack and the...allows the water vapor to be condensed and returned to the electrolyser for consumption will be required. Those items were not available commercially to...charged continuously. The batteries then feed an electrolyzer, which fills up an H2 reservoir that feeds a NEXA 1.2 kW PEMFC stack. The water produced in

  19. Metabolism of ibuprofen in higher plants: A model Arabidopsis thaliana cell suspension culture system

    Czech Academy of Sciences Publication Activity Database

    Maršík, Petr; Šíša, Miroslav; Lacina, O.; Moťková, Kateřina; Langhansová, Lenka; Rezek, Jan; Vaněk, Tomáš

    2017-01-01

    Roč. 220, JAN (2017), s. 383-392 ISSN 0269-7491 R&D Projects: GA ČR(CZ) GA14-22593S Grant - others:European Regional Development Fund(XE) CZ.2.16/3.1.00/24014 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * Ibuprofen * Metabolism * Plant cells * Sequestration Subject RIV: CE - Biochemistry OBOR OECD: Plant sciences, botany Impact factor: 5.099, year: 2016

  20. Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

    International Nuclear Information System (INIS)

    Matsumoto, Takuro; Miyazaki, Tetsuo; Kosugi, Yoshio; Kumada, Takayuki; Koyama, Sinji; Kodama, Seiji; Watanabe, Masami.

    1996-01-01

    When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ) that is a model system of cells is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 K and 310 K for such a long time as 20 hr. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by addition of vitamin C. The isotope effect on the rate constant (k) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (k H /k D ) was more than 20-50 and was interpreted in terms of tunneling reaction. When GHE cells or the aqueous albumin solution (0.1 kg dm -3 ) is irradiated with γ-rays at 295 K, organic radicals produced survive for more than 24 hr at room temperature. Very recently we have found that vitamin C reacts with the long-lived organic radicals in the γ-irradiated albumin solution at high concentration of 0.1 kg dm -3 by the rate constant of 0.014 dm 3 mol -1 s -1 . Since most of reactions in biological systems including the reaction of vitamin C are a transfer of a hydrogen atom or a proton that has a large wave character, it is generally expected that the tunneling reaction may play an important role in biological systems at room temperature. The studies of isotope effects on reactions will give an information on the contribution of tunneling reaction. (J.P.N.)

  1. AlgiMatrix™ based 3D cell culture system as an in-vitro tumor model for anticancer studies.

    Directory of Open Access Journals (Sweden)

    Chandraiah Godugu

    Full Text Available Three-dimensional (3D in-vitro cultures are recognized for recapitulating the physiological microenvironment and exhibiting high concordance with in-vivo conditions. Taking the advantages of 3D culture, we have developed the in-vitro tumor model for anticancer drug screening.Cancer cells grown in 6 and 96 well AlgiMatrix™ scaffolds resulted in the formation of multicellular spheroids in the size range of 100-300 µm. Spheroids were grown in two weeks in cultures without compromising the growth characteristics. Different marketed anticancer drugs were screened by incubating them for 24 h at 7, 9 and 11 days in 3D cultures and cytotoxicity was measured by AlamarBlue® assay. Effectiveness of anticancer drug treatments were measured based on spheroid number and size distribution. Evaluation of apoptotic and anti-apoptotic markers was done by immunohistochemistry and RT-PCR. The 3D results were compared with the conventional 2D monolayer cultures. Cellular uptake studies for drug (Doxorubicin and nanoparticle (NLC were done using spheroids.IC(50 values for anticancer drugs were significantly higher in AlgiMatrix™ systems compared to 2D culture models. The cleaved caspase-3 expression was significantly decreased (2.09 and 2.47 folds respectively for 5-Fluorouracil and Camptothecin in H460 spheroid cultures compared to 2D culture system. The cytotoxicity, spheroid size distribution, immunohistochemistry, RT-PCR and nanoparticle penetration data suggested that in vitro tumor models show higher resistance to anticancer drugs and supporting the fact that 3D culture is a better model for the cytotoxic evaluation of anticancer drugs in vitro.The results from our studies are useful to develop a high throughput in vitro tumor model to study the effect of various anticancer agents and various molecular pathways affected by the anticancer drugs and formulations.

  2. On-line experimental validation of a model-based diagnostic algorithm dedicated to a solid oxide fuel cell system

    Science.gov (United States)

    Polverino, Pierpaolo; Esposito, Angelo; Pianese, Cesare; Ludwig, Bastian; Iwanschitz, Boris; Mai, Andreas

    2016-02-01

    In the current energetic scenario, Solid Oxide Fuel Cells (SOFCs) exhibit appealing features which make them suitable for environmental-friendly power production, especially for stationary applications. An example is represented by micro-combined heat and power (μ-CHP) generation units based on SOFC stacks, which are able to produce electric and thermal power with high efficiency and low pollutant and greenhouse gases emissions. However, the main limitations to their diffusion into the mass market consist in high maintenance and production costs and short lifetime. To improve these aspects, the current research activity focuses on the development of robust and generalizable diagnostic techniques, aimed at detecting and isolating faults within the entire system (i.e. SOFC stack and balance of plant). Coupled with appropriate recovery strategies, diagnosis can prevent undesired system shutdowns during faulty conditions, with consequent lifetime increase and maintenance costs reduction. This paper deals with the on-line experimental validation of a model-based diagnostic algorithm applied to a pre-commercial SOFC system. The proposed algorithm exploits a Fault Signature Matrix based on a Fault Tree Analysis and improved through fault simulations. The algorithm is characterized on the considered system and it is validated by means of experimental induction of faulty states in controlled conditions.

  3. Cell culture models of biological barriers: in vitro test systems for drug absorption and delivery

    National Research Council Canada - National Science Library

    Lehr, Claus-Michael

    2002-01-01

    ... may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. Every effort has been made to ensure that the advice and information in this book is t...

  4. Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

    International Nuclear Information System (INIS)

    Matsumoto, Takuro; Kumada, Takayuki; Kodama, Seiji; Watanabe, Masami

    1997-01-01

    When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ), that is a model system of cells, is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 and 310 K for as long as 20 h. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by the addition of vitamin C. The isotope effect on the rate constant (κ) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (κ H /κ D ) was more than 20 ∼ 50 and was interpreted in terms of tunnelling reaction. (author)

  5. Advanced cathode materials for polymer electrolyte fuel cells based on pt/ metal oxides: from model electrodes to catalyst systems.

    Science.gov (United States)

    Fabbri, Emiliana; Pătru, Alexandra; Rabis, Annett; Kötz, Rüdiger; Schmidt, Thomas J

    2014-01-01

    The development of stable catalyst systems for application at the cathode side of polymer electrolyte fuel cells (PEFCs) requires the substitution of the state-of-the-art carbon supports with materials showing high corrosion resistance in a strongly oxidizing environment. Metal oxides in their highest oxidation state can represent viable support materials for the next generation PEFC cathodes. In the present work a multilevel approach has been adopted to investigate the kinetics and the activity of Pt nanoparticles supported on SnO2-based metal oxides. Particularly, model electrodes made of SnO2 thin films supporting Pt nanoparticles, and porous catalyst systems made of Pt nanoparticles supported on Sb-doped SnO2 high surface area powders have been investigated. The present results indicate that SnO2-based supports do not modify the oxygen reduction reaction mechanism on the Pt nanoparticle surface, but rather lead to catalysts with enhanced specific activity compared to Pt/carbon systems. Different reasons for the enhancement in the specific activity are considered and discussed.

  6. Model-based development of low-level control strategies for transient operation of solid oxide fuel cell systems

    Science.gov (United States)

    Sorrentino, Marco; Pianese, Cesare

    The exploitation of an SOFC-system model to define and test control and energy management strategies is presented. Such a work is motivated by the increasing interest paid to SOFC technology by industries and governments due to its highly appealing potentialities in terms of energy savings, fuel flexibility, cogeneration, low-pollution and low-noise operation. The core part of the model is the SOFC stack, surrounded by a number of auxiliary devices, i.e. air compressor, regulating pressure valves, heat exchangers, pre-reformer and post-burner. Due to the slow thermal dynamics of SOFCs, a set of three lumped-capacity models describes the dynamic response of fuel cell and heat exchangers to any operation change. The dynamic model was used to develop low-level control strategies aimed at guaranteeing targeted performance while keeping stack temperature derivative within safe limits to reduce stack degradation due to thermal stresses. Control strategies for both cold-start and warmed-up operations were implemented by combining feedforward and feedback approaches. Particularly, the main cold-start control action relies on the precise regulation of methane flow towards anode and post-burner via by-pass valves; this strategy is combined with a cathode air-flow adjustment to have a tight control of both stack temperature gradient and warm-up time. Results are presented to show the potentialities of the proposed model-based approach to: (i) serve as a support to control strategies development and (ii) solve the trade-off between fast SOFC cold-start and avoidance of thermal-stress caused damages.

  7. Modeling Viral Infectious Diseases and Development of Antiviral Therapies Using Human Induced Pluripotent Stem Cell-Derived Systems.

    Science.gov (United States)

    Trevisan, Marta; Sinigaglia, Alessandro; Desole, Giovanna; Berto, Alessandro; Pacenti, Monia; Palù, Giorgio; Barzon, Luisa

    2015-07-13

    The recent biotechnology breakthrough of cell reprogramming and generation of induced pluripotent stem cells (iPSCs), which has revolutionized the approaches to study the mechanisms of human diseases and to test new drugs, can be exploited to generate patient-specific models for the investigation of host-pathogen interactions and to develop new antimicrobial and antiviral therapies. Applications of iPSC technology to the study of viral infections in humans have included in vitro modeling of viral infections of neural, liver, and cardiac cells; modeling of human genetic susceptibility to severe viral infectious diseases, such as encephalitis and severe influenza; genetic engineering and genome editing of patient-specific iPSC-derived cells to confer antiviral resistance.

  8. Modeling Viral Infectious Diseases and Development of Antiviral Therapies Using Human Induced Pluripotent Stem Cell-Derived Systems

    Directory of Open Access Journals (Sweden)

    Marta Trevisan

    2015-07-01

    Full Text Available The recent biotechnology breakthrough of cell reprogramming and generation of induced pluripotent stem cells (iPSCs, which has revolutionized the approaches to study the mechanisms of human diseases and to test new drugs, can be exploited to generate patient-specific models for the investigation of host–pathogen interactions and to develop new antimicrobial and antiviral therapies. Applications of iPSC technology to the study of viral infections in humans have included in vitro modeling of viral infections of neural, liver, and cardiac cells; modeling of human genetic susceptibility to severe viral infectious diseases, such as encephalitis and severe influenza; genetic engineering and genome editing of patient-specific iPSC-derived cells to confer antiviral resistance.

  9. Complex Systems Analysis of Cell Cycling Models in Carcinogenesis:II. Cell Genome and Interactome, Neoplastic Non-random Transformation Models in Topoi with Lukasiewicz-Logic and MV Algebras

    CERN Document Server

    Baianu, I C

    2004-01-01

    Quantitative Biology, abstract q-bio.OT/0406045 From: I.C. Baianu Dr. [view email] Date (v1): Thu, 24 Jun 2004 02:45:13 GMT (164kb) Date (revised v2): Fri, 2 Jul 2004 00:58:06 GMT (160kb) Complex Systems Analysis of Cell Cycling Models in Carcinogenesis: II. Authors: I.C. Baianu Comments: 23 pages, 1 Figure Report-no: CC04 Subj-class: Other Carcinogenesis is a complex process that involves dynamically inter-connected modular sub-networks that evolve under the influence of micro-environmentally induced perturbations, in non-random, pseudo-Markov chain processes. An appropriate n-stage model of carcinogenesis involves therefore n-valued Logic treatments of nonlinear dynamic transformations of complex functional genomes and cell interactomes. Lukasiewicz Algebraic Logic models of genetic networks and signaling pathways in cells are formulated in terms of nonlinear dynamic systems with n-state components that allow for the generalization of previous, Boolean or "fuzzy", logic models of genetic activities in vivo....

  10. Mathematical model of the glucose-insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    Science.gov (United States)

    Han, Kyungreem; Kang, Hyuk; Choi, M. Y.; Kim, Jinwoong; Lee, Myung-Shik

    2012-10-01

    A theoretical approach to the glucose-insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca2+ concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose-insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  11. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes control...

  12. Systems biology modeling reveals a possible mechanism of the tumor cell death upon oncogene inactivation in EGFR addicted cancers.

    Directory of Open Access Journals (Sweden)

    Jian-Ping Zhou

    Full Text Available Despite many evidences supporting the concept of "oncogene addiction" and many hypotheses rationalizing it, there is still a lack of detailed understanding to the precise molecular mechanism underlying oncogene addiction. In this account, we developed a mathematic model of epidermal growth factor receptor (EGFR associated signaling network, which involves EGFR-driving proliferation/pro-survival signaling pathways Ras/extracellular-signal-regulated kinase (ERK and phosphoinositol-3 kinase (PI3K/AKT, and pro-apoptotic signaling pathway apoptosis signal-regulating kinase 1 (ASK1/p38. In the setting of sustained EGFR activation, the simulation results show a persistent high level of proliferation/pro-survival effectors phospho-ERK and phospho-AKT, and a basal level of pro-apoptotic effector phospho-p38. The potential of p38 activation (apoptotic potential due to the elevated level of reactive oxygen species (ROS is largely suppressed by the negative crosstalk between PI3K/AKT and ASK1/p38 pathways. Upon acute EGFR inactivation, the survival signals decay rapidly, followed by a fast increase of the apoptotic signal due to the release of apoptotic potential. Overall, our systems biology modeling together with experimental validations reveals that inhibition of survival signals and concomitant release of apoptotic potential jointly contribute to the tumor cell death following the inhibition of addicted oncogene in EGFR addicted cancers.

  13. Elucidation of Altered Pathways in Tumor-Initiating Cells of Triple-Negative Breast Cancer: A Useful Cell Model System for Drug Screening.

    Science.gov (United States)

    Christensen, Anne G; Ehmsen, Sidse; Terp, Mikkel G; Batra, Richa; Alcaraz, Nicolas; Baumbach, Jan; Noer, Julie B; Moreira, José; Leth-Larsen, Rikke; Larsen, Martin R; Ditzel, Henrik J

    2017-08-01

    A limited number of cancer cells within a tumor are thought to have self-renewing and tumor-initiating capabilities that produce the remaining cancer cells in a heterogeneous tumor mass. Elucidation of central pathways preferentially used by tumor-initiating cells/cancer stem cells (CSCs) may allow their exploitation as potential cancer therapy targets. We used single cell cloning to isolate and characterize four isogenic cell clones from a triple-negative breast cancer cell line; two exhibited mesenchymal-like and two epithelial-like characteristics. Within these pairs, one, but not the other, resulted in tumors in immunodeficient NOD/Shi-scid/IL-2 Rγ null mice and efficiently formed mammospheres. Quantitative proteomics and phosphoproteomics were used to map signaling pathways associated with the tumor-initiating ability. Signaling associated with apoptosis was suppressed in tumor-initiating versus nontumorigenic counterparts with pro-apoptotic proteins, such as Bcl2-associated agonist of cell death (BAD), FAS-associated death domain protein (FADD), and myeloid differentiation primary response protein (MYD88), downregulated in tumor-initiating epithelial-like cells. Functional studies confirmed significantly lower apoptosis in tumor-initiating versus nontumorigenic cells. Moreover, central pathways, including β-catenin and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-related signaling, exhibited increased activation in the tumor-initiating cells. To evaluate the CSC model as a tool for drug screening, we assessed the effect of separately blocking NF-κB and Wnt/β-catenin signaling and found markedly reduced mammosphere formation, particularly for tumor-initiating cells. Similar reduction was also observed using patient-derived primary cancer cells. Furthermore, blocking NF-κB signaling in mice transplanted with tumor-initiating cells significantly reduced tumor outgrowth. Our study demonstrates that suppressed apoptosis, activation

  14. Systems Biology and Stem Cell Pluripotency

    DEFF Research Database (Denmark)

    Mashayekhi, Kaveh; Hall, Vanessa Jane; Freude, Kristine

    2016-01-01

    Recent breakthroughs in stem cell biology have accelerated research in the area of regenerative medicine. Over the past years, it has become possible to derive patient-specific stem cells which can be used to generate different cell populations for potential cell therapy. Systems biological...... modeling of stem cell pluripotency and differentiation have largely been based on prior knowledge of signaling pathways, gene regulatory networks, and epigenetic factors. However, there is a great need to extend the complexity of the modeling and to integrate different types of data, which would further...... improve systems biology and its uses in the field. In this chapter, we first give a general background on stem cell biology and regenerative medicine. Stem cell potency is introduced together with the hierarchy of stem cells ranging from pluripotent embryonic stem cells (ESCs) and induced pluripotent stem...

  15. Modeling long-term host cell-Giardia lamblia interactions in an in vitro co-culture system.

    Directory of Open Access Journals (Sweden)

    Bridget S Fisher

    Full Text Available Globally, there are greater than 700,000 deaths per year associated with diarrheal disease. The flagellated intestinal parasite, Giardia lamblia, is one of the most common intestinal pathogens in both humans and animals throughout the world. While attached to the gastrointestinal epithelium, Giardia induces epithelial cell apoptosis, disrupts tight junctions, and increases intestinal permeability. The underlying cellular and molecular mechanisms of giardiasis, including the role lamina propria immune cells, such as macrophages, play in parasite control or clearance are poorly understood. Thus far, one of the major obstacles in ascertaining the mechanisms of Giardia pathology is the lack of a functionally relevant model for the long-term study of the parasite in vitro. Here we report on the development of an in vitro co-culture model which maintains the basolateral-apical architecture of the small intestine and allows for long-term survival of the parasite. Using transwell inserts, Caco-2 intestinal epithelial cells and IC-21 macrophages are co-cultured in the presence of Giardia trophozoites. Using the developed model, we show that Giardia trophozoites survive over 21 days and proliferate in a combination media of Caco-2 cell and Giardia medium. Giardia induces apoptosis of epithelial cells through caspase-3 activation and macrophages do not abrogate this response. Additionally, macrophages induce Caco-2 cells to secrete the pro-inflammatory cytokines, GRO and IL-8, a response abolished by Giardia indicating parasite induced suppression of the host immune response. The co-culture model provides additional complexity and information when compared to a single-cell model. This model will be a valuable tool for answering long-standing questions on host-parasite biology that may lead to discovery of new therapeutic interventions.

  16. Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant

    Directory of Open Access Journals (Sweden)

    Wang Y

    2015-07-01

    lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day.Conclusion: The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine. Keywords: biocompatibility, cytotoxicity, drug delivery, controlled release, fluorescence colocalization, epirubicin

  17. Establishment and Characterization of a Highly Tumourigenic and Cancer Stem Cell Enriched Pancreatic Cancer Cell Line as a Well Defined Model System

    Science.gov (United States)

    Fredebohm, Johannes; Boettcher, Michael; Eisen, Christian; Gaida, Matthias M.; Heller, Anette; Keleg, Shereen; Tost, Jörg; Greulich-Bode, Karin M.; Hotz-Wagenblatt, Agnes; Lathrop, Mark; Giese, Nathalia A.; Hoheisel, Jörg D.

    2012-01-01

    Standard cancer cell lines do not model the intratumoural heterogeneity situation sufficiently. Clonal selection leads to a homogeneous population of cells by genetic drift. Heterogeneity of tumour cells, however, is particularly critical for therapeutically relevant studies, since it is a prerequisite for acquiring drug resistance and reoccurrence of tumours. Here, we report the isolation of a highly tumourigenic primary pancreatic cancer cell line, called JoPaca-1 and its detailed characterization at multiple levels. Implantation of as few as 100 JoPaca-1 cells into immunodeficient mice gave rise to tumours that were histologically very similar to the primary tumour. The high heterogeneity of JoPaca-1 was reflected by diverse cell morphology and a substantial number of chromosomal aberrations. Comparative whole-genome sequencing of JoPaca-1 and BxPC-3 revealed mutations in genes frequently altered in pancreatic cancer. Exceptionally high expression of cancer stem cell markers and a high clonogenic potential in vitro and in vivo was observed. All of these attributes make this cell line an extremely valuable model to study the biology of and pharmaceutical effects on pancreatic cancer. PMID:23152778

  18. Investigation of the effects of external current systems on the MAGSAT data utilizing grid cell modeling techniques

    Science.gov (United States)

    Klumpar, D. M. (Principal Investigator)

    1982-01-01

    The feasibility of modeling magnetic fields due to certain electrical currents flowing in the Earth's ionosphere and magnetosphere was investigated. A method was devised to carry out forward modeling of the magnetic perturbations that arise from space currents. The procedure utilizes a linear current element representation of the distributed electrical currents. The finite thickness elements are combined into loops which are in turn combined into cells having their base in the ionosphere. In addition to the extensive field modeling, additional software was developed for the reduction and analysis of the MAGSAT data in terms of the external current effects. Direct comparisons between the models and the MAGSAT data are possible.

  19. A Unique Model System for Tumor Progression in GBM Comprising Two Developed Human Neuro-Epithelial Cell Lines with Differential Transforming Potential and Coexpressing Neuronal and Glial Markers

    Directory of Open Access Journals (Sweden)

    Anjali Shiras

    2003-11-01

    Full Text Available The molecular mechanisms involved in tumor progression from a low-grade astrocytoma to the most malignant glioblastoma multiforme (GBM have been hampered due to lack of suitable experimental models. We have established a model of tumor progression comprising of two cell lines derived from the same astrocytoma tumor with a set of features corresponding to low-grade glioma (as in HNGC-1 and high-grade GBM (as in HNGC-2. The HNGC-1 cell line is slowgrowing, contact-inhibited, nontumorigenic, and noninvasive, whereas HNGC-2 is a rapidly proliferating, anchorage-independent, highly tumorigenic, and invasive cell line. The proliferation of cell lines is independent of the addition of exogenous growth factors. Interestingly, the HNGC-2 cell line displays a near-haploid karyotype except for a disomy of chromosome 2. The two cell lines express the neuronal precursor and progenitor markers vimentin, nestin, MAP-2, and NFP160, as well as glial differentiation protein S100μ. The HNGC-1 cell line also expresses markers of mature neurons like Tuj1 and GFAP, an astrocytic differentiation marker, hence contributing toward a more morphologically differentiated phenotype with a propensity for neural differentiation in vitro. Additionally, overexpression of epidermal growth factor receptor and c-erbB2, and loss of fibronectin were observed only in the HNGC-2 cell line, implicating the significance of these pathways in tumor progression. This in vitro model system assumes importance in unraveling the cellular and molecular mechanisms in differentiation, transformation, and gliomagenesis.

  20. In-cell protease assay systems based on trans-localizing molecular beacon proteins using HCV protease as a model system.

    Directory of Open Access Journals (Sweden)

    Jeong Hee Kim

    Full Text Available This study describes a sensitive in-cell protease detection system that enables direct fluorescence detection of a target protease and its inhibition inside living cells. This live-cell imaging system provides a fluorescent molecular beacon protein comprised of an intracellular translocation signal sequence, a protease-specific cleavage sequence, and a fluorescent tag sequence(s. The molecular beacon protein is designed to change its intracellular localization upon cleavage by a target protease, i.e., from the cytosol to a subcellular organelle or from a subcellular organelle to the cytosol. Protease activity can be monitored at the single cell level, and accordingly the entire cell population expressing the protease can be accurately enumerated. The clear cellular change in fluorescence pattern makes this system an ideal tool for various life science and drug discovery research, including high throughput and high content screening applications.

  1. Spontaneous transformation of murine oviductal epithelial cells: A model system to investigate the onset of fallopian-derived tumors

    Directory of Open Access Journals (Sweden)

    MIchael P. Endsley

    2015-07-01

    Full Text Available High-grade serous carcinoma (HGSC is the most lethal ovarian cancer histotype. The fallopian tube secretory epithelial cells (FTSECs are a proposed progenitor cell type. Genetically altered FTSECs form tumors in mice; however, a spontaneous HGSC model has not been described. Apart from a subpopulation of genetically predisposed women, most women develop ovarian cancer spontaneously, which is associated with aging and lifetime ovulations. A murine oviductal cell line (MOELOW was developed and continuously passaged in culture to mimic cellular aging (MOEHIGH. The MOEHIGH cellular model exhibited a loss of acetylated tubulin consistent with an outgrowth of secretory epithelial cells in culture. MOEHIGH cells proliferated significantly faster than MOELOW, and the MOEHIGH cells produced more 2D foci and 3D soft agar colonies as compared to MOELOW. MOEHIGH were xenografted into athymic female nude mice both in the subcutaneous and the intraperiteonal compartments. Only the subcutaneous grafts formed tumors that were negative for cytokeratin, but positive for oviductal markers such as oviductal glycoprotein 1 and Pax8. These tumors were considered to be poorly differentiated carcinoma. The differential molecular profiles between MOEHIGH and MOELOW were determined using RNA-Seq and confirmed by protein expression to uncover pathways important in transformation, like the p53 pathway, the FOXM1 pathway, WNT signaling, and splicing. MOEHIGH had enhanced protein expression of c-myc, Cyclin E, p53 and FOXM1 with reduced expression of p21. MOEHIGH were also less sensitive to cisplatin and DMBA, which induce lesions typically repaired by base-excision repair. A model of spontaneous tumorogenesis was generated starting with normal oviductal cells. Their transition to cancer involved alterations in pathways associated with high-grade serous cancer in humans.

  2. Asymptotic analysis and optimal control of an integro-differential system modelling healthy and cancer cells exposed to chemotherapy

    KAUST Repository

    Pouchol, Camille; Clairambault, Jean; Lorz, Alexander; Tré lat, Emmanuel

    2017-01-01

    to the treatment. We analyse the asymptotic behaviour of the model under constant infusion of drugs. By designing an appropriate Lyapunov function, we prove that both cell densities converge to Dirac masses. We then define an optimal control problem, by considering

  3. A model predictive control strategy for the space heating of a smart building including cogeneration of a fuel cell-electrolyzer system

    DEFF Research Database (Denmark)

    Sossan, Fabrizio; Bindner, Henrik W.; Madsen, Henrik

    2014-01-01

    The objective of this paper is to analyze the value of energy replacement in the context of demand response. Energy replacement is dened as the possibility of the consumer to choose the most convenient source for providing space heating to a smart building according to a dynamic electricity price....... In the proposed setup, heat is provided by conventional electric radiators and a combined heat and power generation system, composed by a fuel cell and an electrolyzer. The energy replacement strategy is formulated using model predictive control and mathematical models of the components involved. Simulations show...... that the predictive energy replacement strategy reduces the operating costs of the system and is able to provide a larger amount of regulating power to the grid. In the paper, we also develop a novel dynamic model of a PEM fuel cell suitable for micro-grid applications. The model is realized applying a grey...

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  5. Mathematical model of the glucose–insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    Energy Technology Data Exchange (ETDEWEB)

    Han, Kyungreem [College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Kang, Hyuk [National Institute for Mathematical Sciences, Daejeon 305-340 (Korea, Republic of); Choi, M.Y., E-mail: mychoi@snu.ac.kr [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, Jinwoong, E-mail: jwkim@snu.ac.kr [College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Myung-Shik [Department of Medicine, Samsung Medical Center, and School of Medicine, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of)

    2012-10-01

    A theoretical approach to the glucose–insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca{sup 2+} concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose–insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination. -- Highlights: ► We present a mathematical model for the glucose–insulin regulatory system. ► This model combines the microscopic insulin secretion mechanism in a pancreatic β-cell and macroscopic glucose dynamics at the whole-body level. ► This work is expected to provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  6. Mathematical model of the glucose–insulin regulatory system: From the bursting electrical activity in pancreatic β-cells to the glucose dynamics in the whole body

    International Nuclear Information System (INIS)

    Han, Kyungreem; Kang, Hyuk; Choi, M.Y.; Kim, Jinwoong; Lee, Myung-Shik

    2012-01-01

    A theoretical approach to the glucose–insulin regulatory system is presented. By means of integrated mathematical modeling and extensive numerical simulations, we probe the cell-level dynamics of the membrane potential, intracellular Ca 2+ concentration, and insulin secretion in pancreatic β-cells, together with the whole-body level glucose–insulin dynamics in the liver, brain, muscle, and adipose tissues. In particular, the three oscillatory modes of insulin secretion are reproduced successfully. Such comprehensive mathematical modeling may provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination. -- Highlights: ► We present a mathematical model for the glucose–insulin regulatory system. ► This model combines the microscopic insulin secretion mechanism in a pancreatic β-cell and macroscopic glucose dynamics at the whole-body level. ► This work is expected to provide a theoretical basis for the simultaneous assessment of the β-cell function and insulin resistance in clinical examination.

  7. [Experimental tumors of the central nervous system: standardisation of a model in rats using the 9L glioma cells].

    Science.gov (United States)

    Michailowsky, Custódio; Niura, Flavio Key; do Valle, Angela C; Sonohara, Shigueko; Meneguin, Thales D'Alessandro; Tsanaclis, Ana Maria C

    2003-06-01

    A number of experimental models have been established during the last decades in order to study tumor biology and the effects of treatment or manipulation of the microenvironment of malignant glial tumors. Even though those models have been well characterised and are, to a certain extent, easily reproducible, there are limitations as to their use and to the interpretation of the results. The aim of this study is to standardize a model of a malignant glial tumor and detect possible events able to modify its development. 9L cells were inoculated intracerebrally in 48 Sprague-Dawley rats; from these, 25 animals were also implanted with a device containing electrodes for the registration of the electroencephalogramm. Animals were daily evaluated by neurologic examination. Twenty four animals developed tumor - 10 animals died either in the immediate pos-operatory period or during evolution; 14 animals did not develop tumor. Macroscopically the tumor was well demarcated from the adjacent brain; by light microscopy the tumor exhibited malignant characteristics as well as extensive infiltration of the brain parenchyma. Diagnosis was that of a malignant astrocytoma. The use of the stereotaxic frame and care to infuse a small volume of liquid containing cells during a period of 120 seconds were the most important procedures to obtain sucess in the model. Additional care should be taken in counting cells in the Neubauer camera and in maintaining cells in constant agitation before injecting the tumor-containing solution. The model here developed was efficient besides being of low cost and of relatively easy execution.

  8. Three-dimensional dynamic modelling of Polymer-Electrolyte-Membrane-Fuel-Cell-Systems; Dreidimensionale dynamische Modellierung und Berechnung von Polymer-Elektrolyt-Membran-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Vath, Andreas

    2008-12-15

    This thesis deals with dynamic and multi-dimensional modelling of Polymer- Electrolyte-Membrane-Fuel-Cells (PEMFC). The developed models include all the different layers of the fuel cell e.g. flow field, gas diffusion layer, catalyst layer and membrane with their particular physical, chemical and electrical characteristics. The simulation results have been verified by detailed measurements performed at the research centre for hydrogen and solar energy in Ulm (ZSW Ulm). The developed three dimensional model describes the time- and spatial-dependent charge and mass transport in a fuel cell. Additionally, this model allows the analysis of critical operating conditions. For example, the current density distribution for different membranes is shown during insufficient humidification which results in local overstraining and degradation. The model also allows to analyse extreme critical operating conditions, e.g. short time breakdown of the humidification. Furthermore, the model shows the available potential of improvement opportunities in power density and efficiency of PEMFC due to optimisation of the gas diffusion layer, the catalyst and membrane. In the second part of the work the application of PEMFC systems for combined heat and power units is described by one-dimensional models for an electrical power range between 1 kW and 5 kW. This model contains the necessary components, e.g. gas processing, humidification, gas supply, fuel cell stack, heat storage, pumps, auxiliary burner, power inverter und additional aggregates. As a main result, it is possible to distinctly reduce the energy demand and the carbon dioxide exhaust for different load profiles. Today the costs for fuel cell systems are considerably higher than that of the conventional electrical energy supply. (orig.)

  9. Fuel cell system with interconnect

    Science.gov (United States)

    Goettler, Richard; Liu, Zhien

    2017-12-12

    The present invention includes a fuel cell system having a plurality of adjacent electrochemical cells formed of an anode layer, a cathode layer spaced apart from the anode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. The fuel cell system also includes at least one interconnect, the interconnect being structured to conduct free electrons between adjacent electrochemical cells. Each interconnect includes a primary conductor embedded within the electrolyte layer and structured to conduct the free electrons.

  10. Modeling and Experimental Test of Grid-Tied Photovoltaic Cell Emulating System in the Stand-alone Mode

    Directory of Open Access Journals (Sweden)

    Vu Minh Phap

    2017-06-01

    Full Text Available In recent decades, generation of electricity from solar arrays has been increased to meet the world's growing energy demand. However, the utilization rate of the power conditioner in the grid-tied solar power system is low because the operation of solar panels is dependent on sunlight. Thus, we studied the method that the small scale wind power generating system in size from a few hundred watts to two or three kilowatts can be connected to the grid-tied power conditioner of the solar power system for residential applications with low power ratings (single phase, size is limited to 10kW by emulating characteristic of the solar panel. In this paper, we introduce the application of the grid-tied PV cell emulating system in the stand-alone mode to improve the utilization rate of the power conditioner. The simulation and experimental test results verify that the PV cell emulating system can operate the power conditioner of the gridtied solar power system.

  11. Quantitative image cytometry measurements of lipids, DNA, CD45 and cytokeratin for circulating tumor cell identification in a model system

    Science.gov (United States)

    Futia, Gregory L.; Qamar, Lubna; Behbakht, Kian; Gibson, Emily A.

    2016-04-01

    Circulating tumor cell (CTC) identification has applications in both early detection and monitoring of solid cancers. The rarity of CTCs, expected at ~1-50 CTCs per million nucleated blood cells (WBCs), requires identifying methods based on biomarkers with high sensitivity and specificity for accurate identification. Discovery of biomarkers with ever higher sensitivity and specificity to CTCs is always desirable to potentially find more CTCs in cancer patients thus increasing their clinical utility. Here, we investigate quantitative image cytometry measurements of lipids with the biomarker panel of DNA, Cytokeratin (CK), and CD45 commonly used to identify CTCs. We engineered a device for labeling suspended cell samples with fluorescent antibodies and dyes. We used it to prepare samples for 4 channel confocal laser scanning microscopy. The total data acquired at high resolution from one sample is ~ 1.3 GB. We developed software to perform the automated segmentation of these images into regions of interest (ROIs) containing individual cells. We quantified image features of total signal, spatial second moment, spatial frequency second moment, and their product for each ROI. We performed measurements on pure WBCs, cancer cell line MCF7 and mixed samples. Multivariable regressions and feature selection were used to determine combination features that are more sensitive and specific than any individual feature separately. We also demonstrate that computation of spatial characteristics provides higher sensitivity and specificity than intensity alone. Statistical models allowed quantification of the required sensitivity and specificity for detecting small levels of CTCs in a human blood sample.

  12. Development of performance model and optimization strategy for standalone operation of CPV-hydrogen system utilizing multi-junction solar cell

    KAUST Repository

    Burhan, Muhammad; Shahzad, Muhammad Wakil; Ng, Kim Choon

    2017-01-01

    Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.

  13. Development of performance model and optimization strategy for standalone operation of CPV-hydrogen system utilizing multi-junction solar cell

    KAUST Repository

    Burhan, Muhammad

    2017-09-16

    Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.

  14. Anaerobic Co-Culture of Mesenchymal Stem Cells and Anaerobic Pathogens - A New In Vitro Model System

    OpenAIRE

    Kriebel, Katja; Biedermann, Anne; Kreikemeyer, Bernd; Lang, Hermann

    2013-01-01

    BACKGROUND: Human mesenchymal stem cells (hMSCs) are multipotent by nature and are originally isolated from bone marrow. In light of a future application of hMSCs in the oral cavity, a body compartment with varying oxygen partial pressures and an omnipresence of different bacterial species i.e. periodontitis pathogens, we performed this study to gain information about the behavior of hMSC in an anaerobic system and the response in interaction with oral bacterial pathogens. METHODOLOGY/PRINCIP...

  15. Systems biomechanics of the cell

    CERN Document Server

    Maly, Ivan V

    2013-01-01

    Systems Biomechanics of the Cell attempts to outline systems biomechanics of the cell as an emergent and promising discipline. The new field owes conceptually to cell mechanics, organism-level systems biomechanics, and biology of biochemical systems. Its distinct methodology is to elucidate the structure and behavior of the cell by analyzing the unintuitive collective effects of elementary physical forces that interact within the heritable cellular framework. The problematics amenable to this approach includes the variety of cellular activities that involve the form and movement of the cell body and boundary (nucleus, centrosome, microtubules, cortex, and membrane). Among the elementary system effects in the biomechanics of the cell, instability of symmetry, emergent irreversibility, and multiperiodic dissipative motion can be noted. Research results from recent journal articles are placed in this unifying framework. It is suggested that the emergent discipline has the potential to expand the spectrum of ques...

  16. Statistical performance of image cytometry for DNA, lipids, cytokeratin, & CD45 in a model system for circulation tumor cell detection.

    Science.gov (United States)

    Futia, Gregory L; Schlaepfer, Isabel R; Qamar, Lubna; Behbakht, Kian; Gibson, Emily A

    2017-07-01

    Detection of circulating tumor cells (CTCs) in a blood sample is limited by the sensitivity and specificity of the biomarker panel used to identify CTCs over other blood cells. In this work, we present Bayesian theory that shows how test sensitivity and specificity set the rarity of cell that a test can detect. We perform our calculation of sensitivity and specificity on our image cytometry biomarker panel by testing on pure disease positive (D + ) populations (MCF7 cells) and pure disease negative populations (D - ) (leukocytes). In this system, we performed multi-channel confocal fluorescence microscopy to image biomarkers of DNA, lipids, CD45, and Cytokeratin. Using custom software, we segmented our confocal images into regions of interest consisting of individual cells and computed the image metrics of total signal, second spatial moment, spatial frequency second moment, and the product of the spatial-spatial frequency moments. We present our analysis of these 16 features. The best performing of the 16 features produced an average separation of three standard deviations between D + and D - and an average detectable rarity of ∼1 in 200. We performed multivariable regression and feature selection to combine multiple features for increased performance and showed an average separation of seven standard deviations between the D + and D - populations making our average detectable rarity of ∼1 in 480. Histograms and receiver operating characteristics (ROC) curves for these features and regressions are presented. We conclude that simple regression analysis holds promise to further improve the separation of rare cells in cytometry applications. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

  17. Theoretical model with experimental validation of a regenerative blower for hydrogen recirculation in a PEM fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Badami, M.; Mura, M. [Dipartimento di Energetica, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino (Italy)

    2010-03-15

    A theoretical model of a regenerative blower used for the hydrogen recirculation of a Proton Exchange Membrane (PEM) fuel cell (FC) for automotive applications has been implemented and validated by means of experimental data. A momentum exchange theory was used to determine the head-flow rate curves, whereas the circulatory flow rate was determined through a theory based on the consideration of the centrifugal force field in the side channel and in the impeller vane grooves. The model allows a good forecast to be made of the blower behaviour, and only needs its main geometrical characteristics and some fluid-dynamic data as input. For this reason, the model could be very interesting, especially during the first sizing and the design activity of the blower. (author)

  18. An innovative thermodynamic model for performance evaluation of photovoltaic systems: Effect of wind speed and cell temperature

    International Nuclear Information System (INIS)

    Kaushik, S.C.; Rawat, Rahul; Manikandan, S.

    2017-01-01

    Highlights: • A novel thermodynamic modelling of photovoltaic energy system has been proposed. • The entropy, optical, thermal, spectral and fill factor losses are assessed. • The expression of energetic and exergetic efficiencies have been derived. • Reversible, endoreversible, exoreversible and irreversible systems are presented. - Abstract: The photovoltaic energy conversion is a thermodynamic system which converts the solar energy to the electrical and thermal energy. In this paper, a novel thermodynamic model of photovoltaic energy conversion system has been proposed on the basis of the first and second law of thermodynamics including entropy generation, optical, thermal, spectral and fill factor losses. Based on the irreversibilities, the proposed model has been classified into four cases i.e. reversible, endoreversible, exoreversible and irreversible systems, for which, the expressions of energetic and exergetic efficiencies have been derived. The upper limit efficiency of an ideal photovoltaic module placed in an irreversible environment, i.e. endoreversible system, is determined to be 82.8%. The effect of wind speed and module temperature on the energetic and exergetic efficiencies, thermodynamic losses and irreversibilities has also been presented.

  19. Modeller af komplicerede systemer

    DEFF Research Database (Denmark)

    Mortensen, J.

    emphasizes their use in relation to technical systems. All the presented models, with the exception of the types presented in chapter 2, are non-theoretical non-formal conceptual network models. Two new model types are presented: 1) The System-Environment model, which describes the environments interaction...... with conceptual modeling in relation to process control. It´s purpose is to present classify and exemplify the use of a set of qualitative model types. Such model types are useful in the early phase of modeling, where no structured methods are at hand. Although the models are general in character, this thesis......This thesis, "Modeller af komplicerede systemer", represents part of the requirements for the Danish Ph.D.degree. Assisting professor John Nørgaard-Nielsen, M.Sc.E.E.Ph.D. has been principal supervisor and professor Morten Lind, M.Sc.E.E.Ph.D. has been assisting supervisor. The thesis is concerned...

  20. Modelling non-homogeneous stochastic reaction-diffusion systems: the case study of gemcitabine-treated non-small cell lung cancer growth.

    Science.gov (United States)

    Lecca, Paola; Morpurgo, Daniele

    2012-01-01

    Reaction-diffusion based models have been widely used in the literature for modeling the growth of solid tumors. Many of the current models treat both diffusion/consumption of nutrients and cell proliferation. The majority of these models use classical transport/mass conservation equations for describing the distribution of molecular species in tumor spheroids, and the Fick's law for describing the flux of uncharged molecules (i.e oxygen, glucose). Commonly, the equations for the cell movement and proliferation are first order differential equations describing the rate of change of the velocity of the cells with respect to the spatial coordinates as a function of the nutrient's gradient. Several modifications of these equations have been developed in the last decade to explicitly indicate that the tumor includes cells, interstitial fluids and extracellular matrix: these variants provided a model of tumor as a multiphase material with these as the different phases. Most of the current reaction-diffusion tumor models are deterministic and do not model the diffusion as a local state-dependent process in a non-homogeneous medium at the micro- and meso-scale of the intra- and inter-cellular processes, respectively. Furthermore, a stochastic reaction-diffusion model in which diffusive transport of the molecular species of nutrients and chemotherapy drugs as well as the interactions of the tumor cells with these species is a novel approach. The application of this approach to he scase of non-small cell lung cancer treated with gemcitabine is also novel. We present a stochastic reaction-diffusion model of non-small cell lung cancer growth in the specification formalism of the tool Redi, we recently developed for simulating reaction-diffusion systems. We also describe how a spatial gradient of nutrients and oncological drugs affects the tumor progression. Our model is based on a generalization of the Fick's first diffusion law that allows to model diffusive transport in non

  1. The systems integration modeling system

    International Nuclear Information System (INIS)

    Danker, W.J.; Williams, J.R.

    1990-01-01

    This paper discusses the systems integration modeling system (SIMS), an analysis tool for the detailed evaluation of the structure and related performance of the Federal Waste Management System (FWMS) and its interface with waste generators. It's use for evaluations in support of system-level decisions as to FWMS configurations, the allocation, sizing, balancing and integration of functions among elements, and the establishment of system-preferred waste selection and sequencing methods and other operating strategies is presented. SIMS includes major analysis submodels which quantify the detailed characteristics of individual waste items, loaded casks and waste packages, simulate the detailed logistics of handling and processing discrete waste items and packages, and perform detailed cost evaluations

  2. A new MATLAB/Simulink model of triple-junction solar cell and MPPT based on artificial neural networks for photovoltaic energy systems

    Directory of Open Access Journals (Sweden)

    Hegazy Rezk

    2015-09-01

    Full Text Available This paper presents a new Matlab/Simulink model of a PV module and a maximum power point tracking (MPPT system for high efficiency InGaP/InGaAs/Ge triple-junction solar cell. The proposed technique is based on Artificial Neural Network. The equivalent circuit model of the triple-junction solar cell includes the parameters of each sub-cell. It is also include the effect of the temperature variations on the energy gap of each sub-cell as well as the diode reverse saturation currents. The implementation of a PV model is based on the triple-junction solar cell in the form of masked block in Matlab/Simulink software package that has a user-friendly icon and dialog. It is fast and accurate technique to follow the maximum power point. The simulation results of the proposed MPPT technique are compared with Perturb and Observe MPPT technique. The output power and energy of the proposed technique are higher than that of the Perturb and Observe MPPT technique. The proposed technique increases the output energy per day for a one PV module from 3.37 kW h to 3.75 kW h, i.e. a percentage of 11.28%.

  3. Dynamical system modeling to simulate donor T cell response to whole exome sequencing-derived recipient peptides: Understanding randomness in alloreactivity incidence following stem cell transplantation.

    Directory of Open Access Journals (Sweden)

    Vishal Koparde

    Full Text Available Quantitative relationship between the magnitude of variation in minor histocompatibility antigens (mHA and graft versus host disease (GVHD pathophysiology in stem cell transplant (SCT donor-recipient pairs (DRP is not established. In order to elucidate this relationship, whole exome sequencing (WES was performed on 27 HLA matched related (MRD, & 50 unrelated donors (URD, to identify nonsynonymous single nucleotide polymorphisms (SNPs. An average 2,463 SNPs were identified in MRD, and 4,287 in URD DRP (p<0.01; resulting peptide antigens that may be presented on HLA class I molecules in each DRP were derived in silico (NetMHCpan ver2.0 and the tissue expression of proteins these were derived from determined (GTex. MRD DRP had an average 3,670 HLA-binding-alloreactive peptides, putative mHA (pmHA with an IC50 of <500 nM, and URD, had 5,386 (p<0.01. To simulate an alloreactive donor cytotoxic T cell response, the array of pmHA in each patient was considered as an operator matrix modifying a hypothetical cytotoxic T cell clonal vector matrix; each responding T cell clone's proliferation was determined by the logistic equation of growth, accounting for HLA binding affinity and tissue expression of each alloreactive peptide. The resulting simulated organ-specific alloreactive T cell clonal growth revealed marked variability, with the T cell count differences spanning orders of magnitude between different DRP. Despite an estimated, uniform set of constants used in the model for all DRP, and a heterogeneously treated group of patients, higher total and organ-specific T cell counts were associated with cumulative incidence of moderate to severe GVHD in recipients. In conclusion, exome wide sequence differences and the variable alloreactive peptide binding to HLA in each DRP yields a large range of possible alloreactive donor T cell responses. Our findings also help understand the apparent randomness observed in the development of alloimmune responses.

  4. Glucose oxidation is critical for CD4+ T cell activation in a mouse model of systemic lupus erythematosus1

    Science.gov (United States)

    Yin, Yiming; Choi, Seung-Chul; Xu, Zhiwei; Zeumer, Leilani; Kanda, Nathalie; Croker, Byron P.; Morel, Laurence

    2015-01-01

    We have previously shown that CD4+ T cells from B6.Sle1.Sle2.Sle3 (TC) lupus mice and patients present a high cellular metabolism, and a treatment combining 2-deoxyglucose (2DG), which inhibits glucose metabolism, and metformin, which inhibits oxygen consumption, normalized lupus T cell functions in vitro and reverted disease in mice. We obtained similar results with B6.lpr mice, another model of lupus, and showed that a continuous treatment is required to maintain the beneficial effect of metabolic inhibitors. Further, we investigated the relative roles of glucose oxidation and pyruvate reduction into lactate in this process.. Treatments of TC mice with either 2DG or metformin were sufficient to prevent autoimmune activation, while their combination was necessary to reverse the process. Treatment of TC mice with dichloroacetate (DCA), an inhibitor of lactate production, failed to effectively prevent or reverse autoimmune pathology. In vitro, CD4+ T cell activation upregulated the expression of genes that favor oxidative phosphorylation. Blocking glucose oxidation inhibited both IFNγ and IL-17 production, which could not be achieved by blocking pyruvate reduction. Overall, our data shows that targeting glucose oxidation is required to prevent or reverse lupus development in mice, which cannot be achieved by simply targeting the pyruvate-lactate conversion. PMID:26608911

  5. Dynamical System Modeling of Immune Reconstitution after Allogeneic Stem Cell Transplantation Identifies Patients at Risk for Adverse Outcomes.

    Science.gov (United States)

    Toor, Amir A; Sabo, Roy T; Roberts, Catherine H; Moore, Bonny L; Salman, Salman R; Scalora, Allison F; Aziz, May T; Shubar Ali, Ali S; Hall, Charles E; Meier, Jeremy; Thorn, Radhika M; Wang, Elaine; Song, Shiyu; Miller, Kristin; Rizzo, Kathryn; Clark, William B; McCarty, John M; Chung, Harold M; Manjili, Masoud H; Neale, Michael C

    2015-07-01

    Systems that evolve over time and follow mathematical laws as they evolve are called dynamical systems. Lymphocyte recovery and clinical outcomes in 41 allograft recipients conditioned using antithymocyte globulin (ATG) and 4.5-Gy total body irradiation were studied to determine if immune reconstitution could be described as a dynamical system. Survival, relapse, and graft-versus-host disease (GVHD) were not significantly different in 2 cohorts of patients receiving different doses of ATG. However, donor-derived CD3(+) cell reconstitution was superior in the lower ATG dose cohort, and there were fewer instances of donor lymphocyte infusion (DLI). Lymphoid recovery was plotted in each individual over time and demonstrated 1 of 3 sigmoid growth patterns: Pattern A (n = 15) had rapid growth with high lymphocyte counts, pattern B (n = 14) had slower growth with intermediate recovery, and pattern C (n = 10) had poor lymphocyte reconstitution. There was a significant association between lymphocyte recovery patterns and both the rate of change of donor-derived CD3(+) at day 30 after stem cell transplantation (SCT) and clinical outcomes. GVHD was observed more frequently with pattern A, relapse and DLI more so with pattern C, with a consequent survival advantage in patients with patterns A and B. We conclude that evaluating immune reconstitution after SCT as a dynamical system may differentiate patients at risk of adverse outcomes and allow early intervention to modulate that risk. Copyright © 2015 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

  6. Stochastic models of cell motility

    DEFF Research Database (Denmark)

    Gradinaru, Cristian

    2012-01-01

    Cell motility and migration are central to the development and maintenance of multicellular organisms, and errors during this process can lead to major diseases. Consequently, the mechanisms and phenomenology of cell motility are currently under intense study. In recent years, a new...... interdisciplinary field focusing on the study of biological processes at the nanoscale level, with a range of technological applications in medicine and biological research, has emerged. The work presented in this thesis is at the interface of cell biology, image processing, and stochastic modeling. The stochastic...... models introduced here are based on persistent random motion, which I apply to real-life studies of cell motility on flat and nanostructured surfaces. These models aim to predict the time-dependent position of cell centroids in a stochastic manner, and conversely determine directly from experimental...

  7. Microfluidic cell culture systems for drug research.

    Science.gov (United States)

    Wu, Min-Hsien; Huang, Song-Bin; Lee, Gwo-Bin

    2010-04-21

    In pharmaceutical research, an adequate cell-based assay scheme to efficiently screen and to validate potential drug candidates in the initial stage of drug discovery is crucial. In order to better predict the clinical response to drug compounds, a cell culture model that is faithful to in vivo behavior is required. With the recent advances in microfluidic technology, the utilization of a microfluidic-based cell culture has several advantages, making it a promising alternative to the conventional cell culture methods. This review starts with a comprehensive discussion on the general process for drug discovery and development, the role of cell culture in drug research, and the characteristics of the cell culture formats commonly used in current microfluidic-based, cell-culture practices. Due to the significant differences in several physical phenomena between microscale and macroscale devices, microfluidic technology provides unique functionality, which is not previously possible by using traditional techniques. In a subsequent section, the niches for using microfluidic-based cell culture systems for drug research are discussed. Moreover, some critical issues such as cell immobilization, medium pumping or gradient generation in microfluidic-based, cell-culture systems are also reviewed. Finally, some practical applications of microfluidic-based, cell-culture systems in drug research particularly those pertaining to drug toxicity testing and those with a high-throughput capability are highlighted.

  8. Modeling collective cell migration in geometric confinement

    Science.gov (United States)

    Tarle, Victoria; Gauquelin, Estelle; Vedula, S. R. K.; D'Alessandro, Joseph; Lim, C. T.; Ladoux, Benoit; Gov, Nir S.

    2017-06-01

    Monolayer expansion has generated great interest as a model system to study collective cell migration. During such an expansion the culture front often develops ‘fingers’, which we have recently modeled using a proposed feedback between the curvature of the monolayer’s leading edge and the outward motility of the edge cells. We show that this model is able to explain the puzzling observed increase of collective cellular migration speed of a monolayer expanding into thin stripes, as well as describe the behavior within different confining geometries that were recently observed in experiments. These comparisons give support to the model and emphasize the role played by the edge cells and the edge shape during collective cell motion.

  9. Contrasting Effects of Systemic Monocyte/Macrophage and CD4+ T Cell Depletion in a Reversible Ureteral Obstruction Mouse Model of Chronic Kidney Disease

    Directory of Open Access Journals (Sweden)

    Lee D. Chaves

    2013-01-01

    Full Text Available Using a reversible UUO model (rUUO, we have demonstrated that C57BL/6 mice are susceptible to development of CKD after obstruction-mediated kidney injury while BALB/c mice are resistant. We hypothesized that selective systemic depletion of subpopulations of inflammatory cells during injury or repair might alter the development of CKD. To investigate the impact of modification of Th-lymphocytes or macrophage responses on development of CKD after rUUO, we used an anti-CD4 antibody (GK1.5 or liposomal clodronate to systemically deplete CD4+ T cells or monocyte/macrophages, respectively, prior to and throughout the rUUO protocol. Flow cytometry and immunohistochemistry confirmed depletion of target cell populations. C57BL/6 mice treated with the GK1.5 antibody to deplete CD4+ T cells had higher BUN levels and delayed recovery from rUUO. Treatment of C57BL/6 mice with liposomal clodronate to deplete monocyte/macrophages led to a relative protection from CKD as assessed by BUN values. Our results demonstrate that modulation of the inflammatory response during injury and repair altered the susceptibility of C57BL/6 mice to development of CKD in our rUUO model.

  10. A hybrid mammalian cell cycle model

    Directory of Open Access Journals (Sweden)

    Vincent Noël

    2013-08-01

    Full Text Available Hybrid modeling provides an effective solution to cope with multiple time scales dynamics in systems biology. Among the applications of this method, one of the most important is the cell cycle regulation. The machinery of the cell cycle, leading to cell division and proliferation, combines slow growth, spatio-temporal re-organisation of the cell, and rapid changes of regulatory proteins concentrations induced by post-translational modifications. The advancement through the cell cycle comprises a well defined sequence of stages, separated by checkpoint transitions. The combination of continuous and discrete changes justifies hybrid modelling approaches to cell cycle dynamics. We present a piecewise-smooth version of a mammalian cell cycle model, obtained by hybridization from a smooth biochemical model. The approximate hybridization scheme, leading to simplified reaction rates and binary event location functions, is based on learning from a training set of trajectories of the smooth model. We discuss several learning strategies for the parameters of the hybrid model.

  11. The Earth System Model

    Science.gov (United States)

    Schoeberl, Mark; Rood, Richard B.; Hildebrand, Peter; Raymond, Carol

    2003-01-01

    The Earth System Model is the natural evolution of current climate models and will be the ultimate embodiment of our geophysical understanding of the planet. These models are constructed from components - atmosphere, ocean, ice, land, chemistry, solid earth, etc. models and merged together through a coupling program which is responsible for the exchange of data from the components. Climate models and future earth system models will have standardized modules, and these standards are now being developed by the ESMF project funded by NASA. The Earth System Model will have a variety of uses beyond climate prediction. The model can be used to build climate data records making it the core of an assimilation system, and it can be used in OSSE experiments to evaluate. The computing and storage requirements for the ESM appear to be daunting. However, the Japanese ES theoretical computing capability is already within 20% of the minimum requirements needed for some 2010 climate model applications. Thus it seems very possible that a focused effort to build an Earth System Model will achieve succcss.

  12. Optimization of Fuel Cell System Operating Conditions for Fuel Cell Vehicles

    OpenAIRE

    Zhao, Hengbing; Burke, Andy

    2008-01-01

    Proton Exchange Membrane fuel cell (PEMFC) technology for use in fuel cell vehicles and other applications has been intensively developed in recent decades. Besides the fuel cell stack, air and fuel control and thermal and water management are major challenges in the development of the fuel cell for vehicle applications. The air supply system can have a major impact on overall system efficiency. In this paper a fuel cell system model for optimizing system operating conditions was developed wh...

  13. RSMASS system model development

    International Nuclear Information System (INIS)

    Marshall, A.C.; Gallup, D.R.

    1998-01-01

    RSMASS system mass models have been used for more than a decade to make rapid estimates of space reactor power system masses. This paper reviews the evolution of the RSMASS models and summarizes present capabilities. RSMASS has evolved from a simple model used to make rough estimates of space reactor and shield masses to a versatile space reactor power system model. RSMASS uses unique reactor and shield models that permit rapid mass optimization calculations for a variety of space reactor power and propulsion systems. The RSMASS-D upgrade of the original model includes algorithms for the balance of the power system, a number of reactor and shield modeling improvements, and an automatic mass optimization scheme. The RSMASS-D suite of codes cover a very broad range of reactor and power conversion system options as well as propulsion and bimodal reactor systems. Reactor choices include in-core and ex-core thermionic reactors, liquid metal cooled reactors, particle bed reactors, and prismatic configuration reactors. Power conversion options include thermoelectric, thermionic, Stirling, Brayton, and Rankine approaches. Program output includes all major component masses and dimensions, efficiencies, and a description of the design parameters for a mass optimized system. In the past, RSMASS has been used as an aid to identify and select promising concepts for space power applications. The RSMASS modeling approach has been demonstrated to be a valuable tool for guiding optimization of the power system design; consequently, the model is useful during system design and development as well as during the selection process. An improved in-core thermionic reactor system model RSMASS-T is now under development. The current development of the RSMASS-T code represents the next evolutionary stage of the RSMASS models. RSMASS-T includes many modeling improvements and is planned to be more user-friendly. RSMASS-T will be released as a fully documented, certified code at the end of

  14. A Combined In Vitro Imaging and Multi-Scale Modeling System for Studying the Role of Cell Matrix Interactions in Cutaneous Wound Healing.

    Directory of Open Access Journals (Sweden)

    Aribet M De Jesus

    Full Text Available Many cell types remodel the extracellular matrix of the tissues they inhabit in response to a wide range of environmental stimuli, including mechanical cues. Such is the case in dermal wound healing, where fibroblast migrate into and remodel the provisional fibrin matrix in a complex manner that depends in part on the local mechanical environment and the evolving multi-scale mechanical interactions of the system. In this study, we report on the development of an image-based multi-scale mechanical model that predicts the short-term (24 hours, structural reorganization of a fibrin gel by fibroblasts. These predictive models are based on an in vitro experimental system where clusters of fibroblasts (i.e., explants were spatially arranged into a triangular geometry onto the surface of fibrin gels that were subjected to either Fixed or Free in-plane mechanical constraints. Experimentally, regional differences in short-term structural remodeling and cell migration were observed for the two gel boundary conditions. A pilot experiment indicated that these small differences in the short-term remodeling of the fibrin gel translate into substantial differences in long-term (4 weeks remodeling, particularly in terms of collagen production. The multi-scale models were able to predict some regional differences in remodeling and qualitatively similar reorganization patterns for the two boundary conditions. However, other aspects of the model, such as the magnitudes and rates of deformation of gel, did not match the experiments. These discrepancies between model and experiment provide fertile ground for challenging model assumptions and devising new experiments to enhance our understanding of how this multi-scale system functions. These efforts will ultimately improve the predictions of the remodeling process, particularly as it relates to dermal wound healing and the reduction of patient scarring. Such models could be used to recommend patient

  15. Monitoring stem cell transplantation in rat cerebral ischemic infarction model with 131I-FIAU/TK reporter gene system

    International Nuclear Information System (INIS)

    Wu Tao; An Rui; Zhang Binqing; Sun Xun; Lang Juntao

    2011-01-01

    Objective: To study the biodistribution of 131 I-2'-deoxy-1-β-D-arabinofuranosyl-5-iodouracil (FIAU) in the rat middle cerebral artery occlusion model and the expression of thymidine kinase (TK) gene in brain tissue after gene-modified stem cell transplantation, and thus evaluate the possibility of further noninvasive monitoring of stem cell transplantation therapy in cerebral infarction. Methods: Adenovirus recombinant Ad5-TK-internal ribosome entry site-brain derived heterotrophic factor-enhanced green florescent protein(IRES-BDNF-EGFP) carrying TK-IRES-BDNF gene was prepared. Cerebral infarction model was established in rats by intraluminal middle cerebral artery occlusion with nylon monofilament. Gene modified bone marrow mesenchymal stem cells were transplanted via intraparenchymal route, lateral ventricle, carotid artery and tail vein, respectively. The normal rats were used as controls. 131 I-FAU was prepared to be the tracer for biodistribution study and the % ID/g was calculated based on measurement of the tissue radioactivity counts. The expression of TK gene was evaluated by quantitative real-time PCR (QR-PCR) and Western blot analysis. Data were analyzed with independent-samples t-test, one-way analysis of variance (ANOVA) test, and Pearson linear correlation test. Results: The % ID/g of infarcted brain tissue in the intraparenchymal group was 0.124 ± 0.013, which was significantly higher than that in lateral ventricle group (0.052 ±0.004), carotid artery group (0.061 ±0.002), tail vein group (0.059 ±0.005) and control group (0.005 ±0.001) (t=2.913-5.652, all P<0.05), while there were no statistically significant differences among the other route transplanted groups (t=0.694-1.448, all P>0.05). The differences of % ID/g between the infarcted and contralateral sides of brain tissue in all transplanted groups were statistically significant (t=9.004-15.734, all P<0.05), while there was no statistically significant difference of this parameter

  16. Arabidopsis Regenerating Protoplast: A Powerful Model System for Combining the Proteomics of Cell Wall Proteins and the Visualization of Cell Wall Dynamics

    OpenAIRE

    Yokoyama, Ryusuke; Kuki, Hiroaki; Kuroha, Takeshi; Nishitani, Kazuhiko

    2016-01-01

    The development of a range of sub-proteomic approaches to the plant cell wall has identified many of the cell wall proteins. However, it remains difficult to elucidate the precise biological role of each protein and the cell wall dynamics driven by their actions. The plant protoplast provides an excellent means not only for characterizing cell wall proteins, but also for visualizing the dynamics of cell wall regeneration, during which cell wall proteins are secreted. It therefore offers a uni...

  17. Systemic resilience model

    International Nuclear Information System (INIS)

    Lundberg, Jonas; Johansson, Björn JE

    2015-01-01

    It has been realized that resilience as a concept involves several contradictory definitions, both for instance resilience as agile adjustment and as robust resistance to situations. Our analysis of resilience concepts and models suggest that beyond simplistic definitions, it is possible to draw up a systemic resilience model (SyRes) that maintains these opposing characteristics without contradiction. We outline six functions in a systemic model, drawing primarily on resilience engineering, and disaster response: anticipation, monitoring, response, recovery, learning, and self-monitoring. The model consists of four areas: Event-based constraints, Functional Dependencies, Adaptive Capacity and Strategy. The paper describes dependencies between constraints, functions and strategies. We argue that models such as SyRes should be useful both for envisioning new resilience methods and metrics, as well as for engineering and evaluating resilient systems. - Highlights: • The SyRes model resolves contradictions between previous resilience definitions. • SyRes is a core model for envisioning and evaluating resilience metrics and models. • SyRes describes six functions in a systemic model. • They are anticipation, monitoring, response, recovery, learning, self-monitoring. • The model describes dependencies between constraints, functions and strategies

  18. Selected System Models

    Science.gov (United States)

    Schmidt-Eisenlohr, F.; Puñal, O.; Klagges, K.; Kirsche, M.

    Apart from the general issue of modeling the channel, the PHY and the MAC of wireless networks, there are specific modeling assumptions that are considered for different systems. In this chapter we consider three specific wireless standards and highlight modeling options for them. These are IEEE 802.11 (as example for wireless local area networks), IEEE 802.16 (as example for wireless metropolitan networks) and IEEE 802.15 (as example for body area networks). Each section on these three systems discusses also at the end a set of model implementations that are available today.

  19. Gene Expression of the EGF System-a Prognostic Model in Non-Small Cell Lung Cancer Patients Without Activating EGFR Mutations

    DEFF Research Database (Denmark)

    Sandfeld-Paulsen, Birgitte; Folkersen, Birgitte Holst; Rasmussen, Torben Riis

    2016-01-01

    OBJECTIVES: Contradicting results have been demonstrated for the expression of the epidermal growth factor receptor (EGFR) as a prognostic marker in non-small cell lung cancer (NSCLC). The complexity of the EGF system with four interacting receptors and more than a dozen activating ligands is a l.......17-6.47], P model that takes the complexity of the EGF system into account and shows that this model is a strong prognostic marker in NSCLC patients.......OBJECTIVES: Contradicting results have been demonstrated for the expression of the epidermal growth factor receptor (EGFR) as a prognostic marker in non-small cell lung cancer (NSCLC). The complexity of the EGF system with four interacting receptors and more than a dozen activating ligands...... is a likely explanation. The aim of this study is to demonstrate that the combined network of receptors and ligands from the EGF system is a prognostic marker. MATERIAL AND METHODS: Gene expression of the receptors EGFR, HER2, HER3, HER4, and the ligands AREG, HB-EGF, EPI, TGF-α, and EGF was measured...

  20. Arabidopsis Regenerating Protoplast: A Powerful Model System for Combining the Proteomics of Cell Wall Proteins and the Visualization of Cell Wall Dynamics

    Science.gov (United States)

    Yokoyama, Ryusuke; Kuki, Hiroaki; Kuroha, Takeshi; Nishitani, Kazuhiko

    2016-01-01

    The development of a range of sub-proteomic approaches to the plant cell wall has identified many of the cell wall proteins. However, it remains difficult to elucidate the precise biological role of each protein and the cell wall dynamics driven by their actions. The plant protoplast provides an excellent means not only for characterizing cell wall proteins, but also for visualizing the dynamics of cell wall regeneration, during which cell wall proteins are secreted. It therefore offers a unique opportunity to investigate the de novo construction process of the cell wall. This review deals with sub-proteomic approaches to the plant cell wall through the use of protoplasts, a methodology that will provide the basis for further exploration of cell wall proteins and cell wall dynamics. PMID:28248244

  1. Solar cell power source system

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yoichi; Toma, Kunio; Fukuwa, Shinji

    1988-05-14

    This invention aims to supply a power source system with stable power output by reducing the power loss due to switching in the voltage stabilization even when the power source is a solar cell with frequent voltage variation. For this purpose, in a solar cell power source system consisting of a solar cell, a storage battery, a switching regulator placed between the storage cell and the load, and a load, arrangement was made that, by judging the input voltage from the storage battery, switch-acting the transistor of the switching regulator, if the input voltage is higher than the specified voltage; is the input voltage is lower than the specified voltage, the transistor is put in a full-on state. By this, the supply voltage can be stabilized even when the voltage fluctuates, and system gets more efficient as the switching loss decreases in the voltage stabilizing means. (1 fig)

  2. Inflammatory gene regulatory networks in amnion cells following cytokine stimulation: translational systems approach to modeling human parturition.

    Directory of Open Access Journals (Sweden)

    Ruth Li

    Full Text Available A majority of the studies examining the molecular regulation of human labor have been conducted using single gene approaches. While the technology to produce multi-dimensional datasets is readily available, the means for facile analysis of such data are limited. The objective of this study was to develop a systems approach to infer regulatory mechanisms governing global gene expression in cytokine-challenged cells in vitro, and to apply these methods to predict gene regulatory networks (GRNs in intrauterine tissues during term parturition. To this end, microarray analysis was applied to human amnion mesenchymal cells (AMCs stimulated with interleukin-1β, and differentially expressed transcripts were subjected to hierarchical clustering, temporal expression profiling, and motif enrichment analysis, from which a GRN was constructed. These methods were then applied to fetal membrane specimens collected in the absence or presence of spontaneous term labor. Analysis of cytokine-responsive genes in AMCs revealed a sterile immune response signature, with promoters enriched in response elements for several inflammation-associated transcription factors. In comparison to the fetal membrane dataset, there were 34 genes commonly upregulated, many of which were part of an acute inflammation gene expression signature. Binding motifs for nuclear factor-κB were prominent in the gene interaction and regulatory networks for both datasets; however, we found little evidence to support the utilization of pathogen-associated molecular pattern (PAMP signaling. The tissue specimens were also enriched for transcripts governed by hypoxia-inducible factor. The approach presented here provides an uncomplicated means to infer global relationships among gene clusters involved in cellular responses to labor-associated signals.

  3. Establishment of fruit bat cells (Rousettus aegyptiacus as a model system for the investigation of filoviral infection.

    Directory of Open Access Journals (Sweden)

    Verena Krähling

    Full Text Available BACKGROUND: The fruit bat species Rousettus aegyptiacus was identified as a potential reservoir for the highly pathogenic filovirus Marburg virus. To establish a basis for a molecular understanding of the biology of filoviruses in the reservoir host, we have adapted a set of molecular tools for investigation of filovirus replication in a recently developed cell line, R06E, derived from the species Rousettus aegyptiacus. METHODOLOGY/PRINCIPAL FINDINGS: Upon infection with Ebola or Marburg viruses, R06E cells produced viral titers comparable to VeroE6 cells, as shown by TCID(50 analysis. Electron microscopic analysis of infected cells revealed morphological signs of filovirus infection as described for human- and monkey-derived cell lines. Using R06E cells, we detected an unusually high amount of intracellular viral proteins, which correlated with the accumulation of high numbers of filoviral nucleocapsids in the cytoplasm. We established protocols to produce Marburg infectious virus-like particles from R06E cells, which were then used to infect naïve target cells to investigate primary transcription. This was not possible with other cell lines previously tested. Moreover, we established protocols to reliably rescue recombinant Marburg viruses from R06E cells. CONCLUSION/SIGNIFICANCE: These data indicated that R06E cells are highly suitable to investigate the biology of filoviruses in cells derived from their presumed reservoir.

  4. Modelling spatio-temporal interactions within the cell

    Indian Academy of Sciences (India)

    Prakash

    Cell signalling pathways make up the regulatory systems of mammalian cells. ... This organization makes it possible to study the signalling networks in a modelling ..... energy transfer (FRET) and fluorescence recovery after photobleaching ...

  5. Cardiac Electromechanical Models: From Cell to Organ

    Directory of Open Access Journals (Sweden)

    Natalia A Trayanova

    2011-08-01

    Full Text Available The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computation physiology and medicine. This review focuses on electromechanical (EM models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single cell models and the second half addresses organ models. At the subcelluar level, myofilament models represent actin-myosin interaction and Ca-based activation. Myofilament models and their refinements represent an overview of the development in the field. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered the cellular basis of the Frank-Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction-diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and

  6. Radiobiology of Cell Renewal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Patt, H. M. [Laboratory of Radiobiology, University of California Medical Center, San Francisco, CA (United States)

    1968-08-15

    In recent years, considerable attention has been given to quantitative aspects of radiation effects on cell renewal systems. The behaviour of stem-type cells has been a focal point of interest, and it has been assumed by many that the fraction of surviving stem cells is the principal determinant of the probability of survival of the irradiated system or organism. The apparent close similarity in dose requirements for impairment of reproductive capacity, and the similarity in early repair and in stage sensitivity in vitro and in vivo.clearly indicate that purely cellular phenomena are reflected in the organized population. It does not necessarily follow, however, that there is a straightforward relationship between radiation effects on stem cells and the response of systems or organisms. Indeed, this is not so. It is abundantly clear that differential radiosensitivity is anchored in a number of variables that are associated with the organizational framework of the system and its environment. Many, but not all, effects can be understood in terms of the normal kinetics of the developmental pathway. Yet, deviations from normal kinetics that are minor in the steady state can have profound significance in the perturbed state. To understand the radiobiology of cell renewal systems and to place the many possible variables in reasonable perspective, we need to know a good deal more about the interplay of the component parts than we do at present. When we view the totality of an organized cell population, it seems necessary to postulate mechanisms external to any given cell in the regulation of the balanced sequence of proliferation and differentiation. At present, we have only a vague idea about this. Most attention has been directed to the proliferative process and it is encouraging to note the growing interest in the more developmental facets of cell renewal. (author)

  7. Modeling Sustainable Food Systems.

    Science.gov (United States)

    Allen, Thomas; Prosperi, Paolo

    2016-05-01

    The processes underlying environmental, economic, and social unsustainability derive in part from the food system. Building sustainable food systems has become a predominating endeavor aiming to redirect our food systems and policies towards better-adjusted goals and improved societal welfare. Food systems are complex social-ecological systems involving multiple interactions between human and natural components. Policy needs to encourage public perception of humanity and nature as interdependent and interacting. The systemic nature of these interdependencies and interactions calls for systems approaches and integrated assessment tools. Identifying and modeling the intrinsic properties of the food system that will ensure its essential outcomes are maintained or enhanced over time and across generations, will help organizations and governmental institutions to track progress towards sustainability, and set policies that encourage positive transformations. This paper proposes a conceptual model that articulates crucial vulnerability and resilience factors to global environmental and socio-economic changes, postulating specific food and nutrition security issues as priority outcomes of food systems. By acknowledging the systemic nature of sustainability, this approach allows consideration of causal factor dynamics. In a stepwise approach, a logical application is schematized for three Mediterranean countries, namely Spain, France, and Italy.

  8. Performance Analysis of Machine-Learning Approaches for Modeling the Charging/Discharging Profiles of Stationary Battery Systems with Non-Uniform Cell Aging

    Directory of Open Access Journals (Sweden)

    Nandha Kumar Kandasamy

    2017-06-01

    Full Text Available The number of Stationary Battery Systems (SBS connected to various power distribution networks across the world has increased drastically. The increase in the integration of renewable energy sources is one of the major contributors to the increase in the number of SBS. SBS are also used in other applications such as peak load management, load-shifting, voltage regulation and power quality improvement. Accurately modeling the charging/discharging characteristics of such SBS at various instances (charging/discharging profile is vital for many applications. Capacity loss due to the aging of the batteries is an important factor to be considered for estimating the charging/discharging profile of SBS more accurately. Empirical modeling is a common approach used in the literature for estimating capacity loss, which is further used for estimating the charging/discharging profiles of SBS. However, in the case of SBS used for renewable integration and other grid related applications, machine-learning (ML based models provide extreme flexibility and require minimal resources for implementation. The models can even leverage existing smart meter data to estimate the charging/discharging profile of SBS. In this paper, an analysis on the performance of different ML approaches that can be applied for lithium iron phosphate battery systems and vanadium redox flow battery systems used as SBS is presented for the scenarios where the aging of individual cells is non-uniform.

  9. A multi-level simulation platform of natural gas internal reforming solid oxide fuel cell-gas turbine hybrid generation system - Part II. Balancing units model library and system simulation

    Science.gov (United States)

    Bao, Cheng; Cai, Ningsheng; Croiset, Eric

    2011-10-01

    Following our integrated hierarchical modeling framework of natural gas internal reforming solid oxide fuel cell (IRSOFC), this paper firstly introduces the model libraries of main balancing units, including some state-of-the-art achievements and our specific work. Based on gPROMS programming code, flexible configuration and modular design are fully realized by specifying graphically all unit models in each level. Via comparison with the steady-state experimental data of Siemens-Westinghouse demonstration system, the in-house multi-level SOFC-gas turbine (GT) simulation platform is validated to be more accurate than the advanced power system analysis tool (APSAT). Moreover, some units of the demonstration system are designed reversely for analysis of a typically part-load transient process. The framework of distributed and dynamic modeling in most of units is significant for the development of control strategies in the future.

  10. A bistable model of cell polarity.

    Directory of Open Access Journals (Sweden)

    Matteo Semplice

    Full Text Available Ultrasensitivity, as described by Goldbeter and Koshland, has been considered for a long time as a way to realize bistable switches in biological systems. It is not as well recognized that when ultrasensitivity and reinforcing feedback loops are present in a spatially distributed system such as the cell plasmamembrane, they may induce bistability and spatial separation of the system into distinct signaling phases. Here we suggest that bistability of ultrasensitive signaling pathways in a diffusive environment provides a basic mechanism to realize cell membrane polarity. Cell membrane polarization is a fundamental process implicated in several basic biological phenomena, such as differentiation, proliferation, migration and morphogenesis of unicellular and multicellular organisms. We describe a simple, solvable model of cell membrane polarization based on the coupling of membrane diffusion with bistable enzymatic dynamics. The model can reproduce a broad range of symmetry-breaking events, such as those observed in eukaryotic directional sensing, the apico-basal polarization of epithelium cells, the polarization of budding and mating yeast, and the formation of Ras nanoclusters in several cell types.

  11. Modeling of a thermally integrated 10 kWe planar solid oxide fuel cell system with anode offgas recycling and internal reforming by discretization in flow direction

    Science.gov (United States)

    Wahl, Stefanie; Segarra, Ana Gallet; Horstmann, Peter; Carré, Maxime; Bessler, Wolfgang G.; Lapicque, François; Friedrich, K. Andreas

    2015-04-01

    Combined heat and power production (CHP) based on solid oxide fuel cells (SOFC) is a very promising technology to achieve high electrical efficiency to cover power demand by decentralized production. This paper presents a dynamic quasi 2D model of an SOFC system which consists of stack and balance of plant and includes thermal coupling between the single components. The model is implemented in Modelica® and validated with experimental data for the stack UI-characteristic and the thermal behavior. The good agreement between experimental and simulation results demonstrates the validity of the model. Different operating conditions and system configurations are tested, increasing the net electrical efficiency to 57% by implementing an anode offgas recycle rate of 65%. A sensitivity analysis of characteristic values of the system like fuel utilization, oxygen-to-carbon ratio and electrical efficiency for different natural gas compositions is carried out. The result shows that a control strategy adapted to variable natural gas composition and its energy content should be developed in order to optimize the operation of the system.

  12. A Prognostic Model to Predict Mortality among Non-Small-Cell Lung Cancer Patients in the U.S. Military Health System.

    Science.gov (United States)

    Lin, Jie; Carter, Corey A; McGlynn, Katherine A; Zahm, Shelia H; Nations, Joel A; Anderson, William F; Shriver, Craig D; Zhu, Kangmin

    2015-12-01

    Accurate prognosis assessment after non-small-cell lung cancer (NSCLC) diagnosis is an essential step for making effective clinical decisions. This study is aimed to develop a prediction model with routinely available variables to assess prognosis in patients with NSCLC in the U.S. Military Health System. We used the linked database from the Department of Defense's Central Cancer Registry and the Military Health System Data Repository. The data set was randomly and equally split into a training set to guide model development and a testing set to validate the model prediction. Stepwise Cox regression was used to identify predictors of survival. Model performance was assessed by calculating area under the receiver operating curves and construction of calibration plots. A simple risk scoring system was developed to aid quick risk score calculation and risk estimation for NSCLC clinical management. The study subjects were 5054 patients diagnosed with NSCLC between 1998 and 2007. Age, sex, tobacco use, tumor stage, histology, surgery, chemotherapy, peripheral vascular disease, cerebrovascular disease, and diabetes mellitus were identified as significant predictors of survival. Calibration showed high agreement between predicted and observed event rates. The area under the receiver operating curves reached 0.841, 0.849, 0.848, and 0.838 during 1, 2, 3, and 5 years, respectively. This is the first NSCLC prognosis model for quick risk assessment within the Military Health System. After external validation, the model can be translated into clinical use both as a web-based tool and through mobile applications easily accessible to physicians, patients, and researchers.

  13. AlgiMatrix™-Based 3D Cell Culture System as an In Vitro Tumor Model: An Important Tool in Cancer Research.

    Science.gov (United States)

    Godugu, Chandraiah; Singh, Mandip

    2016-01-01

    Routinely used two-dimensional cell culture-based models often fail while translating the observations into in vivo models. This setback is more common in cancer research, due to several reasons. The extracellular matrix and cell-to-cell interactions are not present in two-dimensional (2D) cell culture models. Diffusion of drug molecules into cancer cells is hindered by barriers of extracellular components in in vivo conditions, these barriers are absent in 2D cell culture models. To better mimic or simulate the in vivo conditions present in tumors, the current study used the alginate based three-dimensional cell culture (AlgiMatrix™) model, which resembles close to the in vivo tumor models. The current study explains the detailed protocols involved in AlgiMatrix™ based in vitro non-small-cell lung cancer (NSCLC) models. The suitability of this model was studied by evaluating, cytotoxicity, apoptosis, and penetration of nanoparticles into the in vitro tumor spheroids. This study also demonstrated the effect of EphA2 receptor targeted docetaxel-loaded nanoparticles on MDA-MB-468 TNBC cell lines. The methods section is subdivided into three subsections such as (1) preparation of AlgiMatrix™-based 3D in vitro tumor models and cytotoxicity assays, (2) free drug and nanoparticle uptake into spheroid studies, and (3) western blot, IHC, and RT-PCR studies.

  14. Aircraft Fuel Cell Power Systems

    Science.gov (United States)

    Needham, Robert

    2004-01-01

    In recent years, fuel cells have been explored for use in aircraft. While the weight and size of fuel cells allows only the smallest of aircraft to use fuel cells for their primary engines, fuel cells have showed promise for use as auxiliary power units (APUs), which power aircraft accessories and serve as an electrical backup in case of an engine failure. Fuel cell MUS are both more efficient and emit fewer pollutants. However, sea-level fuel cells need modifications to be properly used in aircraft applications. At high altitudes, the ambient air has a much lower pressure than at sea level, which makes it much more difficult to get air into the fuel cell to react and produce electricity. Compressors can be used to pressurize the air, but this leads to added weight, volume, and power usage, all of which are undesirable things. Another problem is that fuel cells require hydrogen to create electricity, and ever since the Hindenburg burst into flames, aircraft carrying large quantities of hydrogen have not been in high demand. However, jet fuel is a hydrocarbon, so it is possible to reform it into hydrogen. Since jet fuel is already used to power conventional APUs, it is very convenient to use this to generate the hydrogen for fuel-cell-based APUs. Fuel cells also tend to get large and heavy when used for applications that require a large amount of power. Reducing the size and weight becomes especially beneficial when it comes to fuel cells for aircraft. My goal this summer is to work on several aspects of Aircraft Fuel Cell Power System project. My first goal is to perform checks on a newly built injector rig designed to test different catalysts to determine the best setup for reforming Jet-A fuel into hydrogen. These checks include testing various thermocouples, transmitters, and transducers, as well making sure that the rig was actually built to the design specifications. These checks will help to ensure that the rig will operate properly and give correct results

  15. Modeling Complex Systems

    CERN Document Server

    Boccara, Nino

    2010-01-01

    Modeling Complex Systems, 2nd Edition, explores the process of modeling complex systems, providing examples from such diverse fields as ecology, epidemiology, sociology, seismology, and economics. It illustrates how models of complex systems are built and provides indispensable mathematical tools for studying their dynamics. This vital introductory text is useful for advanced undergraduate students in various scientific disciplines, and serves as an important reference book for graduate students and young researchers. This enhanced second edition includes: . -recent research results and bibliographic references -extra footnotes which provide biographical information on cited scientists who have made significant contributions to the field -new and improved worked-out examples to aid a student’s comprehension of the content -exercises to challenge the reader and complement the material Nino Boccara is also the author of Essentials of Mathematica: With Applications to Mathematics and Physics (Springer, 2007).

  16. Modeling Complex Systems

    International Nuclear Information System (INIS)

    Schreckenberg, M

    2004-01-01

    This book by Nino Boccara presents a compilation of model systems commonly termed as 'complex'. It starts with a definition of the systems under consideration and how to build up a model to describe the complex dynamics. The subsequent chapters are devoted to various categories of mean-field type models (differential and recurrence equations, chaos) and of agent-based models (cellular automata, networks and power-law distributions). Each chapter is supplemented by a number of exercises and their solutions. The table of contents looks a little arbitrary but the author took the most prominent model systems investigated over the years (and up until now there has been no unified theory covering the various aspects of complex dynamics). The model systems are explained by looking at a number of applications in various fields. The book is written as a textbook for interested students as well as serving as a comprehensive reference for experts. It is an ideal source for topics to be presented in a lecture on dynamics of complex systems. This is the first book on this 'wide' topic and I have long awaited such a book (in fact I planned to write it myself but this is much better than I could ever have written it!). Only section 6 on cellular automata is a little too limited to the author's point of view and one would have expected more about the famous Domany-Kinzel model (and more accurate citation!). In my opinion this is one of the best textbooks published during the last decade and even experts can learn a lot from it. Hopefully there will be an actualization after, say, five years since this field is growing so quickly. The price is too high for students but this, unfortunately, is the normal case today. Nevertheless I think it will be a great success! (book review)

  17. Generation of GHR-modified pigs as Laron syndrome models via a dual-sgRNAs/Cas9 system and somatic cell nuclear transfer.

    Science.gov (United States)

    Yu, Honghao; Long, Weihu; Zhang, Xuezeng; Xu, Kaixiang; Guo, Jianxiong; Zhao, Heng; Li, Honghui; Qing, Yubo; Pan, Weirong; Jia, Baoyu; Zhao, Hong-Ye; Huang, Xingxu; Wei, Hong-Jiang

    2018-02-27

    Laron syndrome is an autosomal disease resulting from mutations in the growth hormone receptor (GHR) gene. The only therapeutic treatment for Laron syndrome is recombinant insulin-like growth factor I (IGF-I), which has been shown to have various side effects. The improved Laron syndrome models are important for better understanding the pathogenesis of the disease and developing corresponding therapeutics. Pigs have become attractive biomedical models for human condition due to similarities in anatomy, physiology, and metabolism relative to humans, which could serve as an appropriate model for Laron syndrome. To further improve the GHR knockout (GHRKO) efficiency and explore the feasibility of precise DNA deletion at targeted sites, the dual-sgRNAs/Cas9 system was designed to target GHR exon 3 in pig fetal fibroblasts (PFFs). The vectors encoding sgRNAs and Cas9 were co-transfected into PFFs by electroporation and GHRKO cell lines were established by single cell cloning culture. Two biallelic knockout cell lines were selected as the donor cell line for somatic cell nuclear transfer for the generation of GHRKO pigs. The genotype of colonies, cloned fetuses and piglets were identified by T7 endonuclease I (T7ENI) assay and sequencing. The GHR expression in the fibroblasts and piglets was analyzed by confocal microscopy, quantitative polymerase chain reaction (q-PCR), western blotting (WB) and immunohistochemical (IHC) staining. The phenotype of GHRKO pigs was recapitulated through level detection of IGF-I and glucose, and measurement of body weight and body size. GHRKO F1 generation were generated by crossing with wild-type pigs, and their genotype was detected by T7ENI assay and sequencing. GHRKO F2 generation was obtained via self-cross of GHRKO F1 pigs. Their genotypes of GHRKO F2 generation was also detected by Sanger sequencing. In total, 19 of 20 single-cell colonies exhibited biallelic modified GHR (95%), and the efficiency of DNA deletion mediated by dual

  18. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  19. NOD/scid IL-2Rgnull mice: a preclinical model system to evaluate human dendritic cell-based vaccine strategies in vivo

    Directory of Open Access Journals (Sweden)

    Spranger Stefani

    2012-02-01

    Full Text Available Abstract Background To date very few systems have been described for preclinical investigations of human cellular therapeutics in vivo. However, the ability to carry out comparisons of new cellular vaccines in vivo would be of substantial interest for design of clinical studies. Here we describe a humanized mouse model to assess the efficacy of various human dendritic cell (DC preparations. Two reconstitution regimes of NOD/scid IL2Rgnull (NSG mice with adult human peripheral blood mononuclear cells (PBMC were evaluated for engraftment using 4-week and 9-week schedules. This led to selection of a simple and rapid protocol for engraftment and vaccine evaluation that encompassed 4 weeks. Methods NSG recipients of human PBMC were engrafted over 14 days and then vaccinated twice with autologous DC via intravenous injection. Three DC vaccine formulations were compared that varied generation time in vitro (3 days versus 7 days and signals for maturation (with or without Toll-like receptor (TLR3 and TLR7/8 agonists using MART-1 as a surrogate antigen, by electroporating mature DC with in vitro transcribed RNA encoding full length protein. After two weekly vaccinations, the splenocyte populations containing human lymphocytes were recovered 7 days later and assessed for MART-1-specific immune responses using MHC-multimer-binding assays and functional assessment of specific killing of melanoma tumor cell lines. Results Human monocyte-derived DC generated in vitro in 3 days induced better MART-1-specific immune responses in the autologous donor T cells present in the humanized NSG mice. Moreover, consistent with our in vitro observations, vaccination using mature DC activated with TLR3 and TLR7/8 agonists resulted in enhanced immune responses in vivo. These findings led to a ranking of the DC vaccine effects in vivo that reflected the hierarchy previously found for these mature DC variations in vitro. Conclusions This humanized mouse model system enables

  20. System equivalent model mixing

    Science.gov (United States)

    Klaassen, Steven W. B.; van der Seijs, Maarten V.; de Klerk, Dennis

    2018-05-01

    This paper introduces SEMM: a method based on Frequency Based Substructuring (FBS) techniques that enables the construction of hybrid dynamic models. With System Equivalent Model Mixing (SEMM) frequency based models, either of numerical or experimental nature, can be mixed to form a hybrid model. This model follows the dynamic behaviour of a predefined weighted master model. A large variety of applications can be thought of, such as the DoF-space expansion of relatively small experimental models using numerical models, or the blending of different models in the frequency spectrum. SEMM is outlined, both mathematically and conceptually, based on a notation commonly used in FBS. A critical physical interpretation of the theory is provided next, along with a comparison to similar techniques; namely DoF expansion techniques. SEMM's concept is further illustrated by means of a numerical example. It will become apparent that the basic method of SEMM has some shortcomings which warrant a few extensions to the method. One of the main applications is tested in a practical case, performed on a validated benchmark structure; it will emphasize the practicality of the method.

  1. Voronoi cell patterns: Theoretical model and applications

    Science.gov (United States)

    González, Diego Luis; Einstein, T. L.

    2011-11-01

    We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We use our model to describe the Voronoi cell patterns of several systems. Specifically, we study the island nucleation with irreversible attachment, the 1D car-parking problem, the formation of second-level administrative divisions, and the pattern formed by the Paris Métro stations.

  2. Promise(s of mesenchymal stem cells as an in vitro model system to depict pre-diabetic/diabetic milieu in WNIN/GR-Ob mutant rats.

    Directory of Open Access Journals (Sweden)

    Soundarya L Madhira

    Full Text Available BACKGROUND: Development of model systems have helped to a large extent, in bridging gap to understand the mechanism(s of disease including diabetes. Interestingly, WNIN/GR-Ob rats (Mutants, established at National Centre for Laboratory Animals (NCLAS of National Institute of Nutrition (NIN, form a suitable model system to study obesity with Type 2 diabetes (T2D demonstrating several secondary complications (cataract, cardiovascular complications, infertility, nephropathy etc. The present study has been carried out to explore the potent application(s of multipotent stem cells such as bone marrow mesenchymal stem cells (BM-MSCs, to portray features of pre-diabetic/T2D vis-à-vis featuring obesity, with impaired glucose tolerance (IGT, hyperinsulinemia (HI and insulin resistance (IR seen with Mutant rats akin to human situation. METHODOLOGY/PRINCIPAL FINDINGS: Primary cultures of BM-MSCs (third passage from Mutants, its lean littermate (Lean and parental control (Control were characterized for: proliferation markers, disease memory to mark obesity/T2D/HI/IR which included phased gene expression studies for adipogenic/pancreatic lineages, inflammatory markers and differentiation ability to form mature adipocytes/Insulin-like cellular aggregates (ILCAs. The data showed that BM-MSCs from Mutant demonstrated a state of disease memory, depicted by an upregulated expression of inflammatory markers (IL-6, TNFα; increased stem cell recruitment (Oct-4, Sox-2 and proliferation rates (CD90+/CD29+, PDA, 'S' phase of cell cycle by FACS and BrdU incorporation; accelerated preadipocyte induction (Dact-1, PPARγ2 with a quantitative increase in mature adipocyte formation (Leptin; ILCAs, which were non-responsive to high glucose did confer the Obese/T2D memory in Mutants. Further, these observations were in compliance with the anthropometric data. CONCLUSIONS: Given the ease of accessibility and availability of MSCs, the present study form the basis to report for

  3. ISABELLE half-cell control system

    International Nuclear Information System (INIS)

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

    1977-01-01

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

  4. A systems toxicology approach identifies Lyn as a key signaling phosphoprotein modulated by mercury in a B lymphocyte cell model

    Energy Technology Data Exchange (ETDEWEB)

    Caruso, Joseph A.; Stemmer, Paul M. [Institute of Environmental Health Sciences, Wayne State University, Detroit, MI (United States); Dombkowski, Alan [Department of Pediatrics, Wayne State University, Detroit, MI (United States); Caruthers, Nicholas J. [Institute of Environmental Health Sciences, Wayne State University, Detroit, MI (United States); Gill, Randall [Department of Immunology and Microbiology, Wayne State University, Detroit, MI (United States); Rosenspire, Allen J., E-mail: arosenspire@wayne.edu [Department of Immunology and Microbiology, Wayne State University, Detroit, MI (United States)

    2014-04-01

    Network and protein–protein interaction analyses of proteins undergoing Hg{sup 2+}-induced phosphorylation and dephosphorylation in Hg{sup 2+}-intoxicated mouse WEHI-231 B cells identified Lyn as the most interconnected node. Lyn is a Src family protein tyrosine kinase known to be intimately involved in the B cell receptor (BCR) signaling pathway. Under normal signaling conditions the tyrosine kinase activity of Lyn is controlled by phosphorylation, primarily of two well known canonical regulatory tyrosine sites, Y-397 and Y-508. However, Lyn has several tyrosine residues that have not yet been determined to play a major role under normal signaling conditions, but are potentially important sites for phosphorylation following mercury exposure. In order to determine how Hg{sup 2+} exposure modulates the phosphorylation of additional residues in Lyn, a targeted MS assay was developed. Initial mass spectrometric surveys of purified Lyn identified 7 phosphorylated tyrosine residues. A quantitative assay was developed from these results using the multiple reaction monitoring (MRM) strategy. WEHI-231 cells were treated with Hg{sup 2+}, pervanadate (a phosphatase inhibitor), or anti-Ig antibody (to stimulate the BCR). Results from these studies showed that the phosphoproteomic profile of Lyn after exposure of the WEHI-231 cells to a low concentration of Hg{sup 2+} closely resembled that of anti-Ig antibody stimulation, whereas exposure to higher concentrations of Hg{sup 2+} led to increases in the phosphorylation of Y-193/Y-194, Y-501 and Y-508 residues. These data indicate that mercury can disrupt a key regulatory signal transduction pathway in B cells and point to phospho-Lyn as a potential biomarker for mercury exposure. - Highlights: • Inorganic mercury (Hg{sup 2+}) induces changes in the WEHI-231 B cell phosphoproteome. • The B cell receptor (BCR) signaling pathway was the pathway most affected by Hg{sup 2+}. • The Src family phosphoprotein kinase Lyn was the

  5. Mechanical Systems, Classical Models

    CERN Document Server

    Teodorescu, Petre P

    2009-01-01

    This third volume completes the Work Mechanical Systems, Classical Models. The first two volumes dealt with particle dynamics and with discrete and continuous mechanical systems. The present volume studies analytical mechanics. Topics like Lagrangian and Hamiltonian mechanics, the Hamilton-Jacobi method, and a study of systems with separate variables are thoroughly discussed. Also included are variational principles and canonical transformations, integral invariants and exterior differential calculus, and particular attention is given to non-holonomic mechanical systems. The author explains in detail all important aspects of the science of mechanics, regarded as a natural science, and shows how they are useful in understanding important natural phenomena and solving problems of interest in applied and engineering sciences. Professor Teodorescu has spent more than fifty years as a Professor of Mechanics at the University of Bucharest and this book relies on the extensive literature on the subject as well as th...

  6. Strain-time cell death threshold for skeletal muscle in a tissue-engineered model system for deep tissue injury

    NARCIS (Netherlands)

    Gefen, A.; Nierop, van B.J.; Bader, D.L.; Oomens, C.W.J.

    2008-01-01

    Deep tissue injury (DTI) is a severe pressure ulcer that results from sustained deformation of muscle tissue overlying bony prominences. In order to understand the etiology of DTI, it is essential to determine the tolerance of muscle cells to large mechanical strains. In this study, a new

  7. Inecalcitol, an analog of 1,25D₃, displays enhanced antitumor activity through the induction of apoptosis in a squamous cell carcinoma model system

    Science.gov (United States)

    Ma, Yingyu; Yu, Wei-Dong; Hidalgo, Alejandro A.; Luo, Wei; Delansorne, Remi; Johnson, Candace S.; Trump, Donald L.

    2013-01-01

    Epidemiological data suggest an important role of vitamin D signaling in cancer development and progression, and experimental studies demonstrate that the active vitamin D metabolite 1α, 25-dihydroxyvitamin D₃ (1,25D₃) has broad spectrum antitumor activity. Hypercalcemia has often been suggested to limit the clinical application of these data. The 14-epi-analog of 1,25D₃, inecalcitol [19-nor-14-epi-23-yne-1,25-(OH)₂D₃; TX522], was developed to have superagonistic antitumor activities but low hypercalcemia potential. We examined the antitumor activity of inecalcitol and the underlying mechanisms in a murine squamous cell carcinoma (SCC) model system. In vitro, compared with 1,25D₃, inecalcitol showed enhanced vitamin D receptor (VDR)-mediated transcriptional activity. Inecalcitol suppressed SCC cell proliferation in a dose-dependent manner with an IC₅₀ value 30 times lower than that of 1,25D₃. Both inecalcitol and 1,25D₃ induced a comparable level of G₀/G₁ cell cycle arrest in SCC cells. The level of apoptosis induced by inecalcitol was markedly higher than that of 1,25D₃. Apoptosis was mediated through the activation of the caspase 8/10- caspase 3 pathway. Further, inecalcitol markedly inhibited the mRNA and protein expression of c-IAP1 and XIAP compared with 1,25D₃. In vivo, inecalcitol inhibits SCC tumor growth in a dose-dependent fashion. Notably, inecalcitol induced a significantly higher level of apoptosis in the SCC xenograft model. While in vitro inecalcitol demonstrates apparent enhanced VDR binding and antiproliferative effects compared to 1,25D₃, in vivo these advantages disappear; at doses of inecalcitol that have equivalent antitumor effects, similar hypercalcemia is seen. This may be explained by the pharmacokinetics of 1,25D₃ vs. inecalcitol and attributed to the much shorter serum half-life of inecalcitol.We show that inecalcitol has potent antitumor activity in the SCC model system, and this is associated with a

  8. Glial Cells: The Other Cells of the Nervous System

    Indian Academy of Sciences (India)

    nervous system. The present .... In the vertebrate nervous system, special types of cells called radial glia .... As men- tioned earlier, astrocytes extend a 'foot process' (Figure 3) that ... capillaries that for a long time it was thought that these cells.

  9. Modeling dental radiographic systems

    International Nuclear Information System (INIS)

    Webber, R.L.

    1980-01-01

    The Bureau of Radiological Health has been actively collaborating with the Clinical Investigations Branch, NIDR, in applied research involving diagnostic use of ionizing radiation in dentistry. This work has centered on the search for alternatives to conventional radiographic systems in an attempt to improve diagnostic performance while reducing the required exposure. The basic approach involves analysis of factors limiting performance of properly defined diagnostic tasks and the modeling alternative systems with an eye toward increasing objective measures of performance. Previous collaborative work involved using a nonlinear model to compare various x-ray spectra. The data were expressed as brightness-contrast versus exposure for simulated tasks of clinical interest. This report supplements these findings by extending the number of parameters under investigation and modifying the mode of data display so that an actual radiographic image can be simulated on a television screen

  10. Modeling Novo Nordisk Production Systems

    DEFF Research Database (Denmark)

    Miller, Thomas Dedenroth

    1997-01-01

    This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'.......This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'....

  11. Physiopathology of blood platelets: a model system for studies of cell-to-cell interaction. Progress report, November 1, 1978-October 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, M G

    1979-01-01

    In this report, we will limit ourselves to the detailed description of four major sections of our research done during the past year: platelet interaction with tumor cells; studies of the interaction of platelets with macrophages; interaction of platelets with vessel walls; and further studies of cyclic nucleotides on stored platelets.

  12. A quantitative system for discriminating induced pluripotent stem cells, embryonic stem cells and somatic cells.

    Directory of Open Access Journals (Sweden)

    Anyou Wang

    Full Text Available Induced pluripotent stem cells (iPSCs derived from somatic cells (SCs and embryonic stem cells (ESCs provide promising resources for regenerative medicine and medical research, leading to a daily identification of new cell lines. However, an efficient system to discriminate the different types of cell lines is lacking. Here, we develop a quantitative system to discriminate the three cell types, iPSCs, ESCs, and SCs. The system consists of DNA-methylation biomarkers and mathematical models, including an artificial neural network and support vector machines. All biomarkers were unbiasedly selected by calculating an eigengene score derived from analysis of genome-wide DNA methylations. With 30 biomarkers, or even with as few as 3 top biomarkers, this system can discriminate SCs from pluripotent cells (PCs, including ESCs and iPSCs with almost 100% accuracy. With approximately 100 biomarkers, the system can distinguish ESCs from iPSCs with an accuracy of 95%. This robust system performs precisely with raw data without normalization as well as with converted data in which the continuous methylation levels are accounted. Strikingly, this system can even accurately predict new samples generated from different microarray platforms and the next-generation sequencing. The subtypes of cells, such as female and male iPSCs and fetal and adult SCs, can also be discriminated with this method. Thus, this novel quantitative system works as an accurate framework for discriminating the three cell types, iPSCs, ESCs, and SCs. This strategy also supports the notion that DNA-methylation generally varies among the three cell types.

  13. Mechatronics in fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Stefanopoulou, Anna G.; Kyungwon Suh [Mechanical Engineering Department, University of Michigan, 1231 Beal Avenue, Ann Arbor, MI 48109, (United States)

    2007-03-15

    Power generation from fuel cells (FCs) requires the integration of chemical, fluid, mechanical, thermal, electrical, and electronic subsystems. This integration presents many challenges and opportunities in the mechatronics field. This paper highlights important design issues and poses problems that require mechatronics solutions. The paper begins by describing the process of designing a toy school bus powered by hydrogen for an undergraduate student project. The project was an effective and rewarding educational activity that revealed complex systems issues associated with FC technology. (Author)

  14. Hydrogen fuel cell power system

    International Nuclear Information System (INIS)

    Lam, A.W.

    2004-01-01

    'Full text:' Batteries are typically a necessary and prime component of any DC power system, providing a source of on-demand stored energy with proven reliability. The integration of batteries and basic fuel cells for mobile and stationary utility applications poses a new challenge. For high value applications, the specification and operating requirements for this hybrid module differ from conventional requirements as the module must withstand extreme weather conditions and provide extreme reliability. As an electric utility company, BCHydro has embarked in the development and application of a Hydrogen Fuel Cell Power Supply (HFCPS) for field trial. A Proton Exchange Membrane (PEM)- type fuel cell including power electronic modules are mounted in a standard 19-inch rack that provides 48V, 24V, 12V DC and 120V AC outputs. The hydrogen supply consists of hydrogen bottles and regulating devices to provide a continuous fuel source to the power modules. Many tests and evaluations have been done to ensure the HFCPS package is robust and suitable for electric utility grade operation. A field trial demonstrating this standalone system addressed reliability, durability, and installation concerns as well as developed the overall system operating procedures. (author)

  15. Computer support for physiological cell modelling using an ontology on cell physiology.

    Science.gov (United States)

    Takao, Shimayoshi; Kazuhiro, Komurasaki; Akira, Amano; Takeshi, Iwashita; Masanori, Kanazawa; Tetsuya, Matsuda

    2006-01-01

    The development of electrophysiological whole cell models to support the understanding of biological mechanisms is increasing rapidly. Due to the complexity of biological systems, comprehensive cell models, which are composed of many imported sub-models of functional elements, can get quite complicated as well, making computer modification difficult. Here, we propose a computer support to enhance structural changes of cell models, employing the markup languages CellML and our original PMSML (physiological model structure markup language), in addition to a new ontology for cell physiological modelling. In particular, a method to make references from CellML files to the ontology and a method to assist manipulation of model structures using markup languages together with the ontology are reported. Using these methods three software utilities, including a graphical model editor, are implemented. Experimental results proved that these methods are effective for the modification of electrophysiological models.

  16. On the Action of General Anesthetics on Cellular Function: Barbiturate Alters the Exocytosis of Catecholamines in a Model Cell System.

    Science.gov (United States)

    Ye, Daixin; Ewing, Andrew

    2018-01-22

    General anesthetics are essential in many areas, however, the cellular mechanisms of anesthetic-induced amnesia and unconsciousness are incompletely understood. Exocytosis is the main mechanism of signal transduction and neuronal communication through the release of chemical transmitters from vesicles to the extracellular environment. Here, we use disk electrodes placed on top of PC12 cells to show that treatment with barbiturate induces fewer molecules released during exocytosis and changes the event dynamics perhaps by inducing a less stable fusion pore that is prone to close faster during partial exocytosis. Larger events are essentially abolished. However, use of intracellular vesicle impact electrochemical cytometry using a nano-tip electrode inserted into a cell shows that the distribution of vesicle transmitter content does not change after barbiturate treatment. This indicates that barbiturate selectively alters the pore size of larger events or perhaps differentially between types of vesicles. Alteration of exocytosis in this manner could be linked to the effects of general anesthetics on memory loss. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Stress Erythropoiesis Model Systems.

    Science.gov (United States)

    Bennett, Laura F; Liao, Chang; Paulson, Robert F

    2018-01-01

    Bone marrow steady-state erythropoiesis maintains erythroid homeostasis throughout life. This process constantly generates new erythrocytes to replace the senescent erythrocytes that are removed by macrophages in the spleen. In contrast, anemic or hypoxic stress induces a physiological response designed to increase oxygen delivery to the tissues. Stress erythropoiesis is a key component of this response. It is best understood in mice where it is extramedullary occurring in the adult spleen and liver and in the fetal liver during development. Stress erythropoiesis utilizes progenitor cells and signals that are distinct from bone marrow steady-state erythropoiesis. Because of that observation many genes may play a role in stress erythropoiesis despite having no effect on steady-state erythropoiesis. In this chapter, we will discuss in vivo and in vitro techniques to study stress erythropoiesis in mice and how the in vitro culture system can be extended to study human stress erythropoiesis.

  18. Development and Validation of a Simple Analytical Model of the Proton Exchange Membrane Fuel Cell (Pemfc) in a Fork-Lift Truck Power System

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Rokni, Masoud

    2013-01-01

    In this study, a general proton exchange membrane fuel cell (PEMFC) model has been developed in order to investigate the balance of plant of a fork-lift truck thermodynamically. The model takes into account the effects of pressure losses, water crossovers, humidity aspects, and voltage overpotent......In this study, a general proton exchange membrane fuel cell (PEMFC) model has been developed in order to investigate the balance of plant of a fork-lift truck thermodynamically. The model takes into account the effects of pressure losses, water crossovers, humidity aspects, and voltage...

  19. Cell-based DNA demethylation detection system for screening of epigenetic drugs in 2D, 3D and xenograft models

    Czech Academy of Sciences Publication Activity Database

    Agrawal, K.; Das, V.; Otmar, Miroslav; Krečmerová, Marcela; Džubák, P.; Hajdúch, M.

    2015-01-01

    Roč. 14, Suppl 2 (2015), B72 ISSN 1535-7163. [AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics. 05.11.2015-09.11.2015, Boston] R&D Projects: GA MPO(CZ) FR-TI4/625; GA MŠk(CZ) LO1304 Institutional support: RVO:61388963 Keywords : demethylation * epigenetic drugs * fluorescence detection system Subject RIV: CC - Organic Chemistry

  20. Cell-based DNA demethylation detection system for screening of epigenetic drugs in 2D, 3D, and xenograft models

    Czech Academy of Sciences Publication Activity Database

    Agrawal, K.; Das, V.; Otmar, Miroslav; Krečmerová, Marcela; Džubák, P.; Hajdúch, M.

    91A, č. 2 (2017), s. 133-143 ISSN 1552-4922 R&D Projects: GA MZd(CZ) NV15-31984A; GA MŠk(CZ) LO1304; GA MŠk(CZ) LM2015064; GA TA ČR(CZ) TE01020028 Institutional support: RVO:61388963 Keywords : DNA methylation * DNA methylation inhibitors * demethylation detection system * epigenetic drugs * high content screening Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.222, year: 2016

  1. Fuel cell system blower configuration

    Science.gov (United States)

    Patel, Kirtikumar H.; Saito, Kazuo

    2017-11-28

    An exemplary fuel cell system includes a cell stack assembly having a plurality of cathode components and a plurality of anode components. A first reactant blower has an outlet situated to provide a first reactant to the cathode components. A second reactant blower has an outlet situated to provide a second reactant to the anode components. The second reactant blower includes a fan portion that moves the second reactant through the outlet. The second reactant blower also includes a motor portion that drives the fan portion and a bearing portion associated with the fan portion and the motor portion. The motor portion has a motor coolant inlet coupled with the outlet of the first reactant blower to receive some of the first reactant for cooling the motor portion.

  2. Multiphysics Based Thermal Modeling of a Pouch Lithium-Ion Battery Cell for the Development of Pack Level Thermal Management System

    DEFF Research Database (Denmark)

    Khan, Mohammad Rezwan; Kær, Søren Knudsen

    2016-01-01

    The research is focused on the development of a three-dimensional cell level multiphysics battery thermal model. The primary aim is to represent the cooling mechanism inside the unit cell battery pack. It is accomplished through the coupling of heat transfer and computational fluid dynamics (CFD......) physics. A lumped value of heat generation (HG) inside the battery cell is used. It stems from isothermal calorimeter experiment. HG depends on current rate and the corresponding operating temperature. It is demonstrated that the developed model provides a deeper understanding of the thermal spatio......-temporal behavior of Li-ion battery in different operating conditions....

  3. Thermal Design for Extra-Terrestrial Regenerative Fuel Cell System

    Science.gov (United States)

    Gilligan, R.; Guzik, M.; Jakupca, I.; Bennett, W.; Smith, P.; Fincannon, J.

    2017-01-01

    The Advanced Exploration Systems (AES) Advanced Modular Power Systems (AMPS) Project is investigating different power systems for various lunar and Martian mission concepts. The AMPS Fuel Cell (FC) team has created two system-level models to evaluate the performance of regenerative fuel cell (RFC) systems employing different fuel cell chemistries. Proton Exchange Membrane fuel cells PEMFCs contain a polymer electrolyte membrane that separates the hydrogen and oxygen cavities and conducts hydrogen cations (protons) across the cell. Solid Oxide fuel cells (SOFCs) operate at high temperatures, using a zirconia-based solid ceramic electrolyte to conduct oxygen anions across the cell. The purpose of the modeling effort is to down select one fuel cell chemistry for a more detailed design effort. Figures of merit include the system mass, volume, round trip efficiency, and electrolyzer charge power required. PEMFCs operate at around 60 C versus SOFCs which operate at temperatures greater than 700 C. Due to the drastically different operating temperatures of the two chemistries the thermal control systems (TCS) differ. The PEM TCS is less complex and is characterized by a single pump cooling loop that uses deionized water coolant and rejects heat generated by the system to the environment via a radiator. The solid oxide TCS has its own unique challenges including the requirement to reject high quality heat and to condense the steam produced in the reaction. This paper discusses the modeling of thermal control systems for an extraterrestrial RFC that utilizes either a PEM or solid oxide fuel cell.

  4. Fluorescent multiplex cell flow systems and methods

    KAUST Repository

    Merzaban, Jasmeen

    2017-06-01

    Systems and methods are provided for simultaneously assaying cell adhesion or cell rolling for multiple cell specimens. One embodiment provides a system for assaying adhesion or cell rolling of multiple cell specimens that includes a confocal imaging system containing a parallel plate flow chamber, a pump in fluid communication with the parallel plate flow chamber via a flow chamber inlet line and a cell suspension in fluid communication with the parallel plate flow chamber via a flow chamber outlet line. The system also includes a laser scanning system in electronic communication with the confocal imaging system, and a computer in communication with the confocal imaging system and laser scanning system. In certain embodiments, the laser scanning system emits multiple electromagnetic wavelengths simultaneously it cause multiple fluorescent labels having different excitation wavelength maximums to fluoresce. The system can simultaneously capture real-time fluorescence images from at least seven cell specimens in the parallel plate flow chamber.

  5. Modelling fuel cell performance using artificial intelligence

    Science.gov (United States)

    Ogaji, S. O. T.; Singh, R.; Pilidis, P.; Diacakis, M.

    Over the last few years, fuel cell technology has been increasing promisingly its share in the generation of stationary power. Numerous pilot projects are operating worldwide, continuously increasing the amount of operating hours either as stand-alone devices or as part of gas turbine combined cycles. An essential tool for the adequate and dynamic analysis of such systems is a software model that enables the user to assess a large number of alternative options in the least possible time. On the other hand, the sphere of application of artificial neural networks has widened covering such endeavours of life such as medicine, finance and unsurprisingly engineering (diagnostics of faults in machines). Artificial neural networks have been described as diagrammatic representation of a mathematical equation that receives values (inputs) and gives out results (outputs). Artificial neural networks systems have the capacity to recognise and associate patterns and because of their inherent design features, they can be applied to linear and non-linear problem domains. In this paper, the performance of the fuel cell is modelled using artificial neural networks. The inputs to the network are variables that are critical to the performance of the fuel cell while the outputs are the result of changes in any one or all of the fuel cell design variables, on its performance. Critical parameters for the cell include the geometrical configuration as well as the operating conditions. For the neural network, various network design parameters such as the network size, training algorithm, activation functions and their causes on the effectiveness of the performance modelling are discussed. Results from the analysis as well as the limitations of the approach are presented and discussed.

  6. Modelling fuel cell performance using artificial intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Ogaji, S.O.T.; Singh, R.; Pilidis, P.; Diacakis, M. [Power Propulsion and Aerospace Engineering Department, Centre for Diagnostics and Life Cycle Costs, Cranfield University (United Kingdom)

    2006-03-09

    Over the last few years, fuel cell technology has been increasing promisingly its share in the generation of stationary power. Numerous pilot projects are operating worldwide, continuously increasing the amount of operating hours either as stand-alone devices or as part of gas turbine combined cycles. An essential tool for the adequate and dynamic analysis of such systems is a software model that enables the user to assess a large number of alternative options in the least possible time. On the other hand, the sphere of application of artificial neural networks has widened covering such endeavours of life such as medicine, finance and unsurprisingly engineering (diagnostics of faults in machines). Artificial neural networks have been described as diagrammatic representation of a mathematical equation that receives values (inputs) and gives out results (outputs). Artificial neural networks systems have the capacity to recognise and associate patterns and because of their inherent design features, they can be applied to linear and non-linear problem domains. In this paper, the performance of the fuel cell is modelled using artificial neural networks. The inputs to the network are variables that are critical to the performance of the fuel cell while the outputs are the result of changes in any one or all of the fuel cell design variables, on its performance. Critical parameters for the cell include the geometrical configuration as well as the operating conditions. For the neural network, various network design parameters such as the network size, training algorithm, activation functions and their causes on the effectiveness of the performance modelling are discussed. Results from the analysis as well as the limitations of the approach are presented and discussed. (author)

  7. Estimating cell capacity for multi-cell electrical energy system

    Science.gov (United States)

    Hashemi, Iman Ahari

    A Multi-Cell Electrical Energy System is a set of batteries that are connected in series. The series batteries provide the required voltage necessary for the contraption. After using the energy that is provided by the batteries, some cells within the system tend to have a lower voltage than the other cells. Also, other factors, such as the number of times a battery has been charged or discharged, how long it has been within the system and many other factors, result in some cells having a lesser capacity compared to the other cells within the system. The outcome is that it lowers the required capacity that the electrical energy system is required to provide. By having an unknown cell capacity within the system, it is unknown how much of a charge can be provided to the system so that the cells are not overcharged or undercharged. Therefore, it is necessary to know the cells capacity within the system. Hence, if we were dealing with a single cell, the capacity could be obtained by a full charge and discharge of the cell. In a series system that contains multiple cells a full charging or discharging cannot happen as it might result in deteriorating the structure of some cells within the system. Hence, to find the capacity of a single cell within an electrical energy system it is required to obtain a method that can estimate the value of each cell within the electrical energy system. To approach this method an electrical energy system is required. The electrical energy system consists of rechargeable non-equal capacity batteries to provide the required energy to the system, a battery management system (BMS) board to monitor the cells voltages, an Arduino board that provides the required communication to BMS board, and the PC, and a software that is able to deliver the required data obtained from the Arduino board to the PC. The outcome, estimating the capacity of a cell within a multi-cell system, can be used in many battery related technologies to obtain unknown

  8. Glial Cells: The Other Cells of the Nervous System

    Indian Academy of Sciences (India)

    nervous system and that glial cells were a mere glue holding neurons in place, Schleich ... fact that these cells did not show any electrical activity like neurons or muscles ... membrane potential higher than that of the surrounding neu- rons.

  9. The mathematical cell model reconstructed from interference microscopy data

    Science.gov (United States)

    Rogotnev, A. A.; Nikitiuk, A. S.; Naimark, O. B.; Nebogatikov, V. O.; Grishko, V. V.

    2017-09-01

    The mathematical model of cell dynamics is developed to link the dynamics of the phase cell thickness with the signs of the oncological pathology. The measurements of irregular oscillations of cancer cells phase thickness were made with laser interference microscope MIM-340 in order to substantiate this model. These data related to the dynamics of phase thickness for different cross-sections of cells (nuclei, nucleolus, and cytoplasm) allow the reconstruction of the attractor of dynamic system. The attractor can be associated with specific types of collective modes of phase thickness responsible for the normal and cancerous cell dynamics. Specific type of evolution operator was determined using an algorithm of designing of the mathematical cell model and temporal phase thickness data for cancerous and normal cells. Qualitative correspondence of attractor types to the cell states was analyzed in terms of morphological signs associated with maximum value of mean square irregular oscillations of phase thickness dynamics.

  10. Stem Cell Models: A Guide to Understand and Mitigate Aging?

    Science.gov (United States)

    Brunauer, Regina; Alavez, Silvestre; Kennedy, Brian K

    2017-01-01

    Aging is studied either on a systemic level using life span and health span of animal models, or on the cellular level using replicative life span of yeast or mammalian cells. While useful in identifying general and conserved pathways of aging, both approaches provide only limited information about cell-type specific causes and mechanisms of aging. Stem cells are the regenerative units of multicellular life, and stem cell aging might be a major cause for organismal aging. Using the examples of hematopoietic stem cell aging and human pluripotent stem cell models, we propose that stem cell models of aging are valuable for studying tissue-specific causes and mechanisms of aging and can provide unique insights into the mammalian aging process that may be inaccessible in simple model organisms. © 2016 S. Karger AG, Basel.

  11. Fostering synergy between cell biology and systems biology.

    Science.gov (United States)

    Eddy, James A; Funk, Cory C; Price, Nathan D

    2015-08-01

    In the shared pursuit of elucidating detailed mechanisms of cell function, systems biology presents a natural complement to ongoing efforts in cell biology. Systems biology aims to characterize biological systems through integrated and quantitative modeling of cellular information. The process of model building and analysis provides value through synthesizing and cataloging information about cells and molecules, predicting mechanisms and identifying generalizable themes, generating hypotheses and guiding experimental design, and highlighting knowledge gaps and refining understanding. In turn, incorporating domain expertise and experimental data is crucial for building towards whole cell models. An iterative cycle of interaction between cell and systems biologists advances the goals of both fields and establishes a framework for mechanistic understanding of the genome-to-phenome relationship. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  12. Battery Cell Balancing System and Method

    Science.gov (United States)

    Davies, Francis J. (Inventor)

    2014-01-01

    A battery cell balancing system is operable to utilize a relatively small number of transformers interconnected with a battery having a plurality of battery cells to selectively charge the battery cells. Windings of the transformers are simultaneously driven with a plurality of waveforms whereupon selected battery cells or groups of cells are selected and charged. A transformer drive circuit is operable to selectively vary the waveforms to thereby vary a weighted voltage associated with each of the battery cells.

  13. Simulations of living cell origins using a cellular automata model.

    Science.gov (United States)

    Ishida, Takeshi

    2014-04-01

    Understanding the generalized mechanisms of cell self-assembly is fundamental for applications in various fields, such as mass producing molecular machines in nanotechnology. Thus, the details of real cellular reaction networks and the necessary conditions for self-organized cells must be elucidated. We constructed a 2-dimensional cellular automata model to investigate the emergence of biological cell formation, which incorporated a looped membrane and a membrane-bound information system (akin to a genetic code and gene expression system). In particular, with an artificial reaction system coupled with a thermal system, the simultaneous formation of a looped membrane and an inner reaction process resulted in a more stable structure. These double structures inspired the primitive biological cell formation process from chemical evolution stage. With a model to simulate cellular self-organization in a 2-dimensional cellular automata model, 3 phenomena could be realized: (1) an inner reaction system developed as an information carrier precursor (akin to DNA); (2) a cell border emerged (akin to a cell membrane); and (3) these cell structures could divide into 2. This double-structured cell was considered to be a primary biological cell. The outer loop evolved toward a lipid bilayer membrane, and inner polymeric particles evolved toward precursor information carriers (evolved toward DNA). This model did not completely clarify all the necessary and sufficient conditions for biological cell self-organization. Further, our virtual cells remained unstable and fragile. However, the "garbage bag model" of Dyson proposed that the first living cells were deficient; thus, it would be reasonable that the earliest cells were more unstable and fragile than the simplest current unicellular organisms.

  14. Biomek Cell Workstation: A Variable System for Automated Cell Cultivation.

    Science.gov (United States)

    Lehmann, R; Severitt, J C; Roddelkopf, T; Junginger, S; Thurow, K

    2016-06-01

    Automated cell cultivation is an important tool for simplifying routine laboratory work. Automated methods are independent of skill levels and daily constitution of laboratory staff in combination with a constant quality and performance of the methods. The Biomek Cell Workstation was configured as a flexible and compatible system. The modified Biomek Cell Workstation enables the cultivation of adherent and suspension cells. Until now, no commercially available systems enabled the automated handling of both types of cells in one system. In particular, the automated cultivation of suspension cells in this form has not been published. The cell counts and viabilities were nonsignificantly decreased for cells cultivated in AutoFlasks in automated handling. The proliferation of manual and automated bioscreening by the WST-1 assay showed a nonsignificant lower proliferation of automatically disseminated cells associated with a mostly lower standard error. The disseminated suspension cell lines showed different pronounced proliferations in descending order, starting with Jurkat cells followed by SEM, Molt4, and RS4 cells having the lowest proliferation. In this respect, we successfully disseminated and screened suspension cells in an automated way. The automated cultivation and dissemination of a variety of suspension cells can replace the manual method. © 2015 Society for Laboratory Automation and Screening.

  15. On Modelling an Immune System

    OpenAIRE

    Monroy, Raúl; Saab, Rosa; Godínez, Fernando

    2004-01-01

    Immune systems of live forms have been an abundant source of inspiration to contemporary computer scientists. Problem solving strategies, stemming from known immune system phenomena, have been successfully applied to challenging problems of modern computing. However, research in artificial immune systems has overlooked establishing a coherent model of known immune system behaviour. This paper aims reports on an preliminary computer model of an immune system, where each immune system component...

  16. Modeling aluminum-air battery systems

    Science.gov (United States)

    Savinell, R. F.; Willis, M. S.

    The performance of a complete aluminum-air battery system was studied with a flowsheet model built from unit models of each battery system component. A plug flow model for heat transfer was used to estimate the amount of heat transferred from the electrolyte to the air stream. The effect of shunt currents on battery performance was found to be insignificant. Using the flowsheet simulator to analyze a 100 cell battery system now under development demonstrated that load current, aluminate concentration, and electrolyte temperature are dominant variables controlling system performance. System efficiency was found to decrease as both load current and aluminate concentration increases. The flowsheet model illustrates the interdependence of separate units on overall system performance.

  17. Modeling and optimization of a heat-pump-assisted high temperature proton exchange membrane fuel cell micro-combined-heat-and-power system for residential applications

    DEFF Research Database (Denmark)

    Arsalis, Alexandros; Kær, Søren Knudsen; Nielsen, Mads Pagh

    2015-01-01

    In this study a micro-combined-heat-and-power (micro-CHP) system is coupled to a vapor-compression heat pump to fulfill the residential needs for heating (space heating and water heating) and electricity in detached single-family households in Denmark. Such a combination is assumed to be attractive...... for application, since both fuel cell technology and electric heat pumps are found to be two of the most efficient technologies for generation/conversion of useful energy. The micro-CHP system is fueled with natural gas and includes a fuel cell stack, a fuel processor and other auxiliary components. The micro......-CHP system assumes heat-led operation, to avoid dumping of heat and the use of complicated thermal energy storage. The overall system is grid-interconnected to allow importing and exporting of electricity as necessary. In this study emphasis is given on the operational characterization of the system...

  18. Molten carbonate fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Yasuhiko; Kinoshita, Mamoru; Murakami, Shuzo; Furukawa, Nobuhiro

    1987-09-26

    Reformed gas or coal gasification gas, etc. is used as the fuel gas for fused carbonate fuel cells, however sulfuric compounds are contained in these gases and even after these gases have been treated beforehand through a desulfurizer, a trace quantity of H/sub 2/S is sent to a fuel electrode. Sulfur oxide which is formed at the time of burning and oxidating the exhaust gas from the fuel electrode is supplied together with the air to an oxygen electrode and becomes sulfate after substituting carbonate, which is the electrolyte of the electrode, causing deterioration of the cell characteristics and durability. With regard to a system that hydrogen rich gas which was reformed from the raw fuel is supplied to a fuel electrode, and its exhaust gas is oxidated through a burner to form carbon dioxide which is supplied together with the air to an oxygen electrode, this invention proposes the prevention of the aforementioned defects by providing at the down stream of the above burner a remover to trap with fused carbonate such sulfur compounds as SO/sub 2/ and SO/sub 3/ in the gas after being oxidated as above. (3 figs)

  19. Running and rotating: modelling the dynamics of migrating cell clusters

    Science.gov (United States)

    Copenhagen, Katherine; Gov, Nir; Gopinathan, Ajay

    Collective motion of cells is a common occurrence in many biological systems, including tissue development and repair, and tumor formation. Recent experiments have shown cells form clusters in a chemical gradient, which display three different phases of motion: translational, rotational, and random. We present a model for cell clusters based loosely on other models seen in the literature that involves a Vicsek-like alignment as well as physical collisions and adhesions between cells. With this model we show that a mechanism for driving rotational motion in this kind of system is an increased motility of rim cells. Further, we examine the details of the relationship between rim and core cells, and find that the phases of the cluster as a whole are correlated with the creation and annihilation of topological defects in the tangential component of the velocity field.

  20. Chip based electroanalytical systems for cell analysis

    DEFF Research Database (Denmark)

    Spegel, C.; Heiskanen, A.; Skjolding, L.H.D.

    2008-01-01

    ' measurements of processes related to living cells, i.e., systems without lysing the cells. The focus is on chip based amperometric and impedimetric cell analysis systems where measurements utilizing solely carbon fiber microelectrodes (CFME) and other nonchip electrode formats, such as CFME for exocytosis...

  1. Spatial Models and Networks of Living Systems

    DEFF Research Database (Denmark)

    Juul, Jeppe Søgaard

    When studying the dynamics of living systems, insight can often be gained by developing a mathematical model that can predict future behaviour of the system or help classify system characteristics. However, in living cells, organisms, and especially groups of interacting individuals, a large number...... variables of the system. However, this approach disregards any spatial structure of the system, which may potentially change the behaviour drastically. An alternative approach is to construct a cellular automaton with nearest neighbour interactions, or even to model the system as a complex network...... with interactions defined by network topology. In this thesis I first describe three different biological models of ageing and cancer, in which spatial structure is important for the system dynamics. I then turn to describe characteristics of ecosystems consisting of three cyclically interacting species...

  2. Glial Cells: The Other Cells of the Nervous System

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 1. Glial Cells: The Other Cells of the Nervous System - An Introduction to Glial Cells. Medha S Rajadhyaksha Yasmin Khan. Series Article Volume 7 Issue 1 January 2002 pp 4-10 ...

  3. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running......The present work involves the development of a model for predicting the dynamic temperature of a high temperature PEM (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype...... the stack at a high stoichiometric air flow. This is possible because of the PBI fuel cell membranes used, and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle and end and predicting the temperatures in these three...

  4. Pembangunan Model Restaurant Management System

    OpenAIRE

    Fredy Jingga; Natalia Limantara

    2014-01-01

    Model design for Restaurant Management System aims to help in restaurant business process, where Restaurant Management System (RMS) help the waitress and chef could interact each other without paper limitation.  This Restaurant Management System Model develop using Agile Methodology and developed based on PHP Programming Langguage. The database management system is using MySQL. This web-based application model will enable the waitress and the chef to interact in realtime, from the time they a...

  5. Supervised learning methods in modeling of CD4+ T cell heterogeneity

    OpenAIRE

    Lu, Pinyi; Abedi, Vida; Mei, Yongguo; Hontecillas, Raquel; Hoops, Stefan; Carbo, Adria; Bassaganya-Riera, Josep

    2015-01-01

    Background Modeling of the immune system – a highly non-linear and complex system – requires practical and efficient data analytic approaches. The immune system is composed of heterogeneous cell populations and hundreds of cell types, such as neutrophils, eosinophils, macrophages, dendritic cells, T cells, and B cells. Each cell type is highly diverse and can be further differentiated into subsets with unique and overlapping functions. For example, CD4+ T cells can be differentiated into T...

  6. A multidisciplinary approach to study the functional properties of neuron-like cell models constituting a living bio-hybrid system: SH-SY5Y cells adhering to PANI substrate

    Directory of Open Access Journals (Sweden)

    S. Caponi

    2016-11-01

    Full Text Available A living bio-hybrid system has been successfully implemented. It is constituted by neuroblastic cells, the SH-SY5Y human neuroblastoma cells, adhering to a poly-anyline (PANI a semiconductor polymer with memristive properties. By a multidisciplinary approach, the biocompatibility of the substrate has been analyzed and the functionality of the adhering cells has been investigated. We found that the PANI films can support the cell adhesion. Moreover, the SH-SY5Y cells were successfully differentiated into neuron-like cells for in vitro applications demonstrating that PANI can also promote cell differentiation. In order to deeply characterize the modifications of the bio-functionality induced by the cell-substrate interaction, the functional properties of the cells have been characterized by electrophysiology and Raman spectroscopy. Our results confirm that the PANI films do not strongly affect the general properties of the cells, ensuring their viability without toxic effects on their physiology. Ascribed to the adhesion process, however, a slight increase of the markers of the cell suffering has been evidenced by Raman spectroscopy and accordingly the electrophysiology shows a reduction at positive stimulations in the cells excitability.

  7. Modeling the Shapes of Cells

    Science.gov (United States)

    Garimella, Umadevi I.; Robertson, Belinda M.

    2015-01-01

    A solid understanding of the structure and function of cells can help establish the foundation for learning advanced concepts in the biological sciences. The concept of the cell is introduced in middle school life science courses and is continued at the undergraduate level in college (NRC 2012; Reece et al. 2014). Cells are introduced to students…

  8. Modelling of wastewater systems

    DEFF Research Database (Denmark)

    Bechmann, Henrik

    to analyze and quantify the effect of the Aeration Tank Settling (ATS) operating mode, which is used during rain events. Furthermore, the model is used to propose a control algorithm for the phase lengths during ATS operation. The models are mainly formulated as state space model in continuous time......In this thesis, models of pollution fluxes in the inlet to 2 Danish wastewater treatment plants (WWTPs) as well as of suspended solids (SS) concentrations in the aeration tanks of an alternating WWTP and in the effluent from the aeration tanks are developed. The latter model is furthermore used...... at modelling the fluxes in terms of the multiple correlation coefficient R2. The model of the SS concentrations in the aeration tanks of an alternating WWTP as well as in the effluent from the aeration tanks is a mass balance model based on measurements of SS in one aeration tank and in the common outlet...

  9. Arrangement of fuel cell system for TNRF

    International Nuclear Information System (INIS)

    Nojima, Takehiro; Yasuda, Ryo; Iikura, Hiroshi; Sakai, Takuro; Matsubayashi, Masahito; Takenaka, Nobuyuki; Hayashida, Hirotoshi

    2012-02-01

    Polymer electrolyte fuel cells (fuel cells) can be potentially employed as sources of clean energy because they discharge only water as by-products. Fuel cells generate electricity with supply of oxygen and hydrogen gases. However, the water produced by the fuel cells blocks the gas supply, thereby degrading their performances. Therefore, it is important to understand the behavior of the water produced by the fuel cells in order to facilitate their development. Neutron radiography is a useful tool for visualizing the distribution of water in fuel cells. We have designed fuel cell operation system for TNRF (Thermal Neutron Radiography Facility) at JRR-3. The fuel cell operation system consists of various components such as gas flow and humidification systems, hydrogen-diluting system, purge system, and safety system for hydrogen gas. We tested this system using a Japan Automobile Research Institute (JARI) standard cell. The system performed stably and efficiently. In addition, neutron radiography tests were carried out to visualize the water distribution. The water produced by the fuel cell was observed during the fuel cell operation. (author)

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

    Science.gov (United States)

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

    2018-03-01

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

  11. Economics of Direct Hydrogen Polymer Electrolyte Membrane Fuel Cell Systems

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Kathyayani

    2011-10-04

    Battelle's Economic Analysis of PEM Fuel Cell Systems project was initiated in 2003 to evaluate the technology and markets that are near-term and potentially could support the transition to fuel cells in automotive markets. The objective of Battelle?s project was to assist the DOE in developing fuel cell systems for pre-automotive applications by analyzing the technical, economic, and market drivers of direct hydrogen PEM fuel cell adoption. The project was executed over a 6-year period (2003 to 2010) and a variety of analyses were completed in that period. The analyses presented in the final report include: Commercialization scenarios for stationary generation through 2015 (2004); Stakeholder feedback on technology status and performance status of fuel cell systems (2004); Development of manufacturing costs of stationary PEM fuel cell systems for backup power markets (2004); Identification of near-term and mid-term markets for PEM fuel cells (2006); Development of the value proposition and market opportunity of PEM fuel cells in near-term markets by assessing the lifecycle cost of PEM fuel cells as compared to conventional alternatives used in the marketplace and modeling market penetration (2006); Development of the value proposition of PEM fuel cells in government markets (2007); Development of the value proposition and opportunity for large fuel cell system application at data centers and wastewater treatment plants (2008); Update of the manufacturing costs of PEM fuel cells for backup power applications (2009).

  12. Modeling and estimating system availability

    International Nuclear Information System (INIS)

    Gaver, D.P.; Chu, B.B.

    1976-11-01

    Mathematical models to infer the availability of various types of more or less complicated systems are described. The analyses presented are probabilistic in nature and consist of three parts: a presentation of various analytic models for availability; a means of deriving approximate probability limits on system availability; and a means of statistical inference of system availability from sparse data, using a jackknife procedure. Various low-order redundant systems are used as examples, but extension to more complex systems is not difficult

  13. Cell boundary fault detection system

    Science.gov (United States)

    Archer, Charles Jens [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Ratterman, Joseph D [Rochester, MN; Smith, Brian Edward [Rochester, MN

    2009-05-05

    A method determines a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

  14. Systems Biology for Organotypic Cell Cultures

    Energy Technology Data Exchange (ETDEWEB)

    Grego, Sonia [RTI International, Research Triangle Park, NC (United States); Dougherty, Edward R. [Texas A & M Univ., College Station, TX (United States); Alexander, Francis J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Auerbach, Scott S. [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States); Berridge, Brian R. [GlaxoSmithKline, Research Triangle Park, NC (United States); Bittner, Michael L. [Translational Genomics Research Inst., Phoenix, AZ (United States); Casey, Warren [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States); Cooley, Philip C. [RTI International, Research Triangle Park, NC (United States); Dash, Ajit [HemoShear Therapeutics, Charlottesville, VA (United States); Ferguson, Stephen S. [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States); Fennell, Timothy R. [RTI International, Research Triangle Park, NC (United States); Hawkins, Brian T. [RTI International, Research Triangle Park, NC (United States); Hickey, Anthony J. [RTI International, Research Triangle Park, NC (United States); Kleensang, Andre [Johns Hopkins Univ., Baltimore, MD (United States). Center for Alternatives to Animal Testing; Liebman, Michael N. [IPQ Analytics, Kennett Square, PA (United States); Martin, Florian [Phillip Morris International, Neuchatel (Switzerland); Maull, Elizabeth A. [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States); Paragas, Jason [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Qiao, Guilin [Defense Threat Reduction Agency, Ft. Belvoir, VA (United States); Ramaiahgari, Sreenivasa [National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States); Sumner, Susan J. [RTI International, Research Triangle Park, NC (United States); Yoon, Miyoung [The Hamner Inst. for Health Sciences, Research Triangle Park, NC (United States); ScitoVation, Research Triangle Park, NC (United States)

    2016-08-04

    Translating in vitro biological data into actionable information related to human health holds the potential to improve disease treatment and risk assessment of chemical exposures. While genomics has identified regulatory pathways at the cellular level, translation to the organism level requires a multiscale approach accounting for intra-cellular regulation, inter-cellular interaction, and tissue/organ-level effects. Tissue-level effects can now be probed in vitro thanks to recently developed systems of three-dimensional (3D), multicellular, “organotypic” cell cultures, which mimic functional responses of living tissue. However, there remains a knowledge gap regarding interactions across different biological scales, complicating accurate prediction of health outcomes from molecular/genomic data and tissue responses. Systems biology aims at mathematical modeling of complex, non-linear biological systems. We propose to apply a systems biology approach to achieve a computational representation of tissue-level physiological responses by integrating empirical data derived from organotypic culture systems with computational models of intracellular pathways to better predict human responses. Successful implementation of this integrated approach will provide a powerful tool for faster, more accurate and cost-effective screening of potential toxicants and therapeutics. On September 11, 2015, an interdisciplinary group of scientists, engineers, and clinicians gathered for a workshop in Research Triangle Park, North Carolina, to discuss this ambitious goal. Participants represented laboratory-based and computational modeling approaches to pharmacology and toxicology, as well as the pharmaceutical industry, government, non-profits, and academia. Discussions focused on identifying critical system perturbations to model, the computational tools required, and the experimental approaches best suited to generating key data. This consensus report summarizes the discussions held.

  15. Recent Advances in Enzymatic Fuel Cells: Experiments and Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Ivanov

    2010-04-01

    Full Text Available Enzymatic fuel cells convert the chemical energy of biofuels into electrical energy. Unlike traditional fuel cell types, which are mainly based on metal catalysts, the enzymatic fuel cells employ enzymes as catalysts. This fuel cell type can be used as an implantable power source for a variety of medical devices used in modern medicine to administer drugs, treat ailments and monitor bodily functions. Some advantages in comparison to conventional fuel cells include a simple fuel cell design and lower cost of the main fuel cell components, however they suffer from severe kinetic limitations mainly due to inefficiency in electron transfer between the enzyme and the electrode surface. In this review article, the major research activities concerned with the enzymatic fuel cells (anode and cathode development, system design, modeling by highlighting the current problems (low cell voltage, low current density, stability will be presented.

  16. A Web-Server of Cell Type Discrimination System

    Directory of Open Access Journals (Sweden)

    Anyou Wang

    2014-01-01

    Full Text Available Discriminating cell types is a daily request for stem cell biologists. However, there is not a user-friendly system available to date for public users to discriminate the common cell types, embryonic stem cells (ESCs, induced pluripotent stem cells (iPSCs, and somatic cells (SCs. Here, we develop WCTDS, a web-server of cell type discrimination system, to discriminate the three cell types and their subtypes like fetal versus adult SCs. WCTDS is developed as a top layer application of our recent publication regarding cell type discriminations, which employs DNA-methylation as biomarkers and machine learning models to discriminate cell types. Implemented by Django, Python, R, and Linux shell programming, run under Linux-Apache web server, and communicated through MySQL, WCTDS provides a friendly framework to efficiently receive the user input and to run mathematical models for analyzing data and then to present results to users. This framework is flexible and easy to be expended for other applications. Therefore, WCTDS works as a user-friendly framework to discriminate cell types and subtypes and it can also be expended to detect other cell types like cancer cells.

  17. Vaccination directed against the human endogenous retrovirus-K (HERV-K) gag protein slows HERV-K gag expressing cell growth in a murine model system.

    Science.gov (United States)

    Kraus, Benjamin; Fischer, Katrin; Sliva, Katja; Schnierle, Barbara S

    2014-03-26

    Human endogenous retroviruses (HERVs) are remnants of ancestral infections and chromosomally integrated in all cells of an individual, are transmitted only vertically and are defective in viral replication. However enhanced expression of HERV-K accompanied by the emergence of anti-HERV-K-directed immune responses has been observed inter-alia in HIV-infected individuals and tumor patients. Therefore HERV-K might serve as a tumor-specific antigen or even as a constant target for the development of an HIV vaccine. To verify our hypothesis, we tested the immunogenicity of HERV-K Gag by using a recombinant vaccinia virus (MVA-HKcon) expressing the HERV-K Gag protein and established an animal model to test its vaccination efficacy. Murine renal carcinoma cells (Renca) were genetically altered to express E. coli beta-galactosidase (RLZ cells) and the HERV-K Gag protein (RLZ-HKGag cells). Subcutaneous application of RLZ-HKGag cells into syngenic BALB/c mice resulted in the formation of local tumors in MVA vaccinated mice. MVA-HKcon vaccination reduced the tumor growth. Furthermore, intravenous injection of RLZ-HKGag cells led to the formation of pulmonary metastases. Vaccination of tumor-bearing mice with MVA-HKcon drastically reduced the number of pulmonary RLZ-HKGag tumor nodules compared to vaccination with wild-type MVA. The data demonstrate that HERV-K Gag is a useful target for vaccine development and might offer new treatment opportunities for cancer patients.

  18. UML as a cell and biochemistry modeling language.

    Science.gov (United States)

    Webb, Ken; White, Tony

    2005-06-01

    The systems biology community is building increasingly complex models and simulations of cells and other biological entities, and are beginning to look at alternatives to traditional representations such as those provided by ordinary differential equations (ODE). The lessons learned over the years by the software development community in designing and building increasingly complex telecommunication and other commercial real-time reactive systems, can be advantageously applied to the problems of modeling in the biology domain. Making use of the object-oriented (OO) paradigm, the unified modeling language (UML) and Real-Time Object-Oriented Modeling (ROOM) visual formalisms, and the Rational Rose RealTime (RRT) visual modeling tool, we describe a multi-step process we have used to construct top-down models of cells and cell aggregates. The simple example model described in this paper includes membranes with lipid bilayers, multiple compartments including a variable number of mitochondria, substrate molecules, enzymes with reaction rules, and metabolic pathways. We demonstrate the relevance of abstraction, reuse, objects, classes, component and inheritance hierarchies, multiplicity, visual modeling, and other current software development best practices. We show how it is possible to start with a direct diagrammatic representation of a biological structure such as a cell, using terminology familiar to biologists, and by following a process of gradually adding more and more detail, arrive at a system with structure and behavior of arbitrary complexity that can run and be observed on a computer. We discuss our CellAK (Cell Assembly Kit) approach in terms of features found in SBML, CellML, E-CELL, Gepasi, Jarnac, StochSim, Virtual Cell, and membrane computing systems.

  19. Modeling soft interface dominated systems

    NARCIS (Netherlands)

    Lamorgese, A.; Mauri, R.; Sagis, L.M.C.

    2017-01-01

    The two main continuum frameworks used for modeling the dynamics of soft multiphase systems are the Gibbs dividing surface model, and the diffuse interface model. In the former the interface is modeled as a two dimensional surface, and excess properties such as a surface density, or surface energy

  20. PEM fuel cell model suitable for energy optimization purposes

    International Nuclear Information System (INIS)

    Caux, S.; Hankache, W.; Fadel, M.; Hissel, D.

    2010-01-01

    Many fuel cell stack models or fuel cell system models exist. A model must be built with a main objective, sometimes for accurate electro-chemical behavior description, sometimes for optimization procedure at a system level. In this paper, based on the fundamental reactions present in a fuel cell stack, an accurate model and identification procedure is presented for future energy management in a Hybrid Electrical Vehicle (HEV). The proposed approach extracts all important state variables in such a system and based on the control of the fuel cell's gas flows and temperature, simplification arises to a simple electrical model. Assumptions verified due to the control of the stack allow simplifying the relationships within keeping accuracy in the description of a global fuel cell stack behavior from current demand to voltage. Modeled voltage and current dynamic behaviors are compared with actual measurements. The obtained accuracy is sufficient and less time-consuming (versus other previously published system-oriented models) leading to a suitable model for optimization iterative off-line algorithms.

  1. PEM fuel cell model suitable for energy optimization purposes

    Energy Technology Data Exchange (ETDEWEB)

    Caux, S.; Hankache, W.; Fadel, M. [LAPLACE/CODIASE: UMR CNRS 5213, Universite de Toulouse - INPT, UPS, - ENSEEIHT: 2 rue Camichel BP7122, 31071 Toulouse (France); CNRS, LAPLACE, F-31071 Toulouse (France); Hissel, D. [FEMTO-ST ENISYS/FCLAB, UMR CNRS 6174, University of Franche-Comte, Rue Thierry Mieg, 90010 Belfort (France)

    2010-02-15

    Many fuel cell stack models or fuel cell system models exist. A model must be built with a main objective, sometimes for accurate electro-chemical behavior description, sometimes for optimization procedure at a system level. In this paper, based on the fundamental reactions present in a fuel cell stack, an accurate model and identification procedure is presented for future energy management in a Hybrid Electrical Vehicle (HEV). The proposed approach extracts all important state variables in such a system and based on the control of the fuel cell's gas flows and temperature, simplification arises to a simple electrical model. Assumptions verified due to the control of the stack allow simplifying the relationships within keeping accuracy in the description of a global fuel cell stack behavior from current demand to voltage. Modeled voltage and current dynamic behaviors are compared with actual measurements. The obtained accuracy is sufficient and less time-consuming (versus other previously published system-oriented models) leading to a suitable model for optimization iterative off-line algorithms. (author)

  2. Modelling collective cell migration of neural crest.

    Science.gov (United States)

    Szabó, András; Mayor, Roberto

    2016-10-01

    Collective cell migration has emerged in the recent decade as an important phenomenon in cell and developmental biology and can be defined as the coordinated and cooperative movement of groups of cells. Most studies concentrate on tightly connected epithelial tissues, even though collective migration does not require a constant physical contact. Movement of mesenchymal cells is more independent, making their emergent collective behaviour less intuitive and therefore lending importance to computational modelling. Here we focus on such modelling efforts that aim to understand the collective migration of neural crest cells, a mesenchymal embryonic population that migrates large distances as a group during early vertebrate development. By comparing different models of neural crest migration, we emphasize the similarity and complementary nature of these approaches and suggest a future direction for the field. The principles derived from neural crest modelling could aid understanding the collective migration of other mesenchymal cell types. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. The overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  4. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Boozer, D.D.; Hulme, B.L.; Daniel, S.L.; Varnado, G.B.; Bennett, H.A.; Chapman, L.D.; Engi, D.

    1976-09-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. In this paper, the overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  5. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. In this paper, the overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  6. ECONOMIC MODELING STOCKS CONTROL SYSTEM: SIMULATION MODEL

    OpenAIRE

    Климак, М.С.; Войтко, С.В.

    2016-01-01

    Considered theoretical and applied aspects of the development of simulation models to predictthe optimal development and production systems that create tangible products andservices. It isproved that theprocessof inventory control needs of economicandmathematical modeling in viewof thecomplexity of theoretical studies. A simulation model of stocks control that allows make managementdecisions with production logistics

  7. Extinction models for cancer stem cell therapy

    Science.gov (United States)

    Sehl, Mary; Zhou, Hua; Sinsheimer, Janet S.; Lange, Kenneth L.

    2012-01-01

    Cells with stem cell-like properties are now viewed as initiating and sustaining many cancers. This suggests that cancer can be cured by driving these cancer stem cells to extinction. The problem with this strategy is that ordinary stem cells are apt to be killed in the process. This paper sets bounds on the killing differential (difference between death rates of cancer stem cells and normal stem cells) that must exist for the survival of an adequate number of normal stem cells. Our main tools are birth–death Markov chains in continuous time. In this framework, we investigate the extinction times of cancer stem cells and normal stem cells. Application of extreme value theory from mathematical statistics yields an accurate asymptotic distribution and corresponding moments for both extinction times. We compare these distributions for the two cell populations as a function of the killing rates. Perhaps a more telling comparison involves the number of normal stem cells NH at the extinction time of the cancer stem cells. Conditioning on the asymptotic time to extinction of the cancer stem cells allows us to calculate the asymptotic mean and variance of NH. The full distribution of NH can be retrieved by the finite Fourier transform and, in some parameter regimes, by an eigenfunction expansion. Finally, we discuss the impact of quiescence (the resting state) on stem cell dynamics. Quiescence can act as a sanctuary for cancer stem cells and imperils the proposed therapy. We approach the complication of quiescence via multitype branching process models and stochastic simulation. Improvements to the τ-leaping method of stochastic simulation make it a versatile tool in this context. We conclude that the proposed therapy must target quiescent cancer stem cells as well as actively dividing cancer stem cells. The current cancer models demonstrate the virtue of attacking the same quantitative questions from a variety of modeling, mathematical, and computational perspectives

  8. A systemic approach to modelling of radiobiological effects

    International Nuclear Information System (INIS)

    Obaturov, G.M.

    1988-01-01

    Basic principles of the systemic approach to modelling of the radiobiological effects at different levels of cell organization have been formulated. The methodology is proposed for theoretical modelling of the effects at these levels

  9. Deconstructing stem cell population heterogeneity: Single-cell analysis and modeling approaches

    Science.gov (United States)

    Wu, Jincheng; Tzanakakis, Emmanuel S.

    2014-01-01

    Isogenic stem cell populations display cell-to-cell variations in a multitude of attributes including gene or protein expression, epigenetic state, morphology, proliferation and proclivity for differentiation. The origins of the observed heterogeneity and its roles in the maintenance of pluripotency and the lineage specification of stem cells remain unclear. Addressing pertinent questions will require the employment of single-cell analysis methods as traditional cell biochemical and biomolecular assays yield mostly population-average data. In addition to time-lapse microscopy and flow cytometry, recent advances in single-cell genomic, transcriptomic and proteomic profiling are reviewed. The application of multiple displacement amplification, next generation sequencing, mass cytometry and spectrometry to stem cell systems is expected to provide a wealth of information affording unprecedented levels of multiparametric characterization of cell ensembles under defined conditions promoting pluripotency or commitment. Establishing connections between single-cell analysis information and the observed phenotypes will also require suitable mathematical models. Stem cell self-renewal and differentiation are orchestrated by the coordinated regulation of subcellular, intercellular and niche-wide processes spanning multiple time scales. Here, we discuss different modeling approaches and challenges arising from their application to stem cell populations. Integrating single-cell analysis with computational methods will fill gaps in our knowledge about the functions of heterogeneity in stem cell physiology. This combination will also aid the rational design of efficient differentiation and reprogramming strategies as well as bioprocesses for the production of clinically valuable stem cell derivatives. PMID:24035899

  10. Engineering models and methods for industrial cell control

    DEFF Research Database (Denmark)

    Lynggaard, Hans Jørgen Birk; Alting, Leo

    1997-01-01

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

  11. Cell boundary fault detection system

    Science.gov (United States)

    Archer, Charles Jens [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Ratterman, Joseph D [Rochester, MN; Smith, Brian Edward [Rochester, MN

    2011-04-19

    An apparatus and program product determine a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

  12. Development, investigation and modelling of a micro reformer as part of a system for off-grid power supply with PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Rochlitz, Lisbeth

    2008-11-18

    In this thesis a micro reformer fuel cell system ({mu}RFCS) for 300 Wel off-grid power supply, fuelled with bioethanol, was simulated, designed, developed and investigated in a test-rig. First a literature study was carried through to point out the specific characteristics of micro reforming, the most important being heat transfer, and present the systems currently under research and already on the market. As a next step, the processes of the RFCS were simulated with the commercial simulation tool CHEMCAD. This comprised thermodynamic equilibrium simulations for the separate reactions of steam reforming, water gas shift and selective methanation. It also included a simulation of the complete {mu}RFCS with thermodynamic equilibrium for all reactors and assumed values for heat loss and fuel cell efficiency. The resulting net electrical efficiency was 24%. As a third step, a reaction pathway scheme with parallel and serial reactions for the steam reforming reaction of ethanol was simulated, developed, evaluated and proven plausible by matching the simulation to experimental results obtained in the {mu}RFCS test rig. The equilibrium simulations were used to evaluate the catalyst screening carried through for reformer, water gas shift and selective methanation catalysts. The catalysts for the {mu}RFCS were chosen and the optimum operating conditions determined by the screening tests. Having accomplished the simulation and design of the system, the largest proportion of this work was spent on the construction, set-up, testing and evaluation of the complete {mu}RFCS. The focus for the evaluations lay on the reformer side of the system. The technical feasibility was demonstrated for an ethanol/water mix of 3 ml/min at S/C 3. The first tests without optimized heat and water management between the reformer system and the fuel cell system resulted in power output of around 115 W{sub el}, at a total electrical efficiency of 31%. (orig.)

  13. Innovative High Temperature Fuel Cell systems

    NARCIS (Netherlands)

    Au, Siu Fai

    2003-01-01

    The world's energy consumption is growing extremely rapidly. Fuel cell systems are of interest by researchers and industry as the more efficient alternative to conventional thermal systems for power generation. The principle of fuel cell conversion does not involve thermal combustion and hence in

  14. Analysis and Design of Fuel Cell Systems for Aviation

    Directory of Open Access Journals (Sweden)

    Thomas Kadyk

    2018-02-01

    Full Text Available In this paper, the design of fuel cells for the main energy supply of passenger transportation aircraft is discussed. Using a physical model of a fuel cell, general design considerations are derived. Considering different possible design objectives, the trade-off between power density and efficiency is discussed. A universal cost–benefit curve is derived to aid the design process. A weight factor w P is introduced, which allows incorporating technical (e.g., system mass and efficiency as well as non-technical design objectives (e.g., operating cost, emission goals, social acceptance or technology affinity, political factors. The optimal fuel cell design is not determined by the characteristics of the fuel cell alone, but also by the characteristics of the other system components. The fuel cell needs to be designed in the context of the whole energy system. This is demonstrated by combining the fuel cell model with simple and detailed design models of a liquid hydrogen tank. The presented methodology and models allows assessing the potential of fuel cell systems for mass reduction of future passenger aircraft.

  15. Application of cell co-culture system to study fat and muscle cells.

    Science.gov (United States)

    Pandurangan, Muthuraman; Hwang, Inho

    2014-09-01

    Animal cell culture is a highly complex process, in which cells are grown under specific conditions. The growth and development of these cells is a highly unnatural process in vitro condition. Cells are removed from animal tissues and artificially cultured in various culture vessels. Vitamins, minerals, and serum growth factors are supplied to maintain cell viability. Obtaining result homogeneity of in vitro and in vivo experiments is rare, because their structure and function are different. Living tissues have highly ordered complex architecture and are three-dimensional (3D) in structure. The interaction between adjacent cell types is quite distinct from the in vitro cell culture, which is usually two-dimensional (2D). Co-culture systems are studied to analyze the interactions between the two different cell types. The muscle and fat co-culture system is useful in addressing several questions related to muscle modeling, muscle degeneration, apoptosis, and muscle regeneration. Co-culture of C2C12 and 3T3-L1 cells could be a useful diagnostic tool to understand the muscle and fat formation in animals. Even though, co-culture systems have certain limitations, they provide a more realistic 3D view and information than the individual cell culture system. It is suggested that co-culture systems are useful in evaluating the intercellular communication and composition of two different cell types.

  16. Synthetic Biology Outside the Cell: Linking Computational Tools to Cell-Free Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Daniel D. [Integrative Genetics and Genomics, University of California Davis, Davis, CA (United States); Department of Biomedical Engineering, University of California Davis, Davis, CA (United States); Villarreal, Fernando D.; Wu, Fan; Tan, Cheemeng, E-mail: cmtan@ucdavis.edu [Department of Biomedical Engineering, University of California Davis, Davis, CA (United States)

    2014-12-09

    As mathematical models become more commonly integrated into the study of biology, a common language for describing biological processes is manifesting. Many tools have emerged for the simulation of in vivo synthetic biological systems, with only a few examples of prominent work done on predicting the dynamics of cell-free synthetic systems. At the same time, experimental biologists have begun to study dynamics of in vitro systems encapsulated by amphiphilic molecules, opening the door for the development of a new generation of biomimetic systems. In this review, we explore both in vivo and in vitro models of biochemical networks with a special focus on tools that could be applied to the construction of cell-free expression systems. We believe that quantitative studies of complex cellular mechanisms and pathways in synthetic systems can yield important insights into what makes cells different from conventional chemical systems.

  17. Synthetic Biology Outside the Cell: Linking Computational Tools to Cell-Free Systems

    Directory of Open Access Journals (Sweden)

    Daniel eLewis

    2014-12-01

    Full Text Available As mathematical models become more commonly integrated into the study of biology, a common language for describing biological processes is manifesting. Many tools have emerged for the simulation of in vivo systems, with only a few examples of prominent work done on predicting the dynamics of cell-free systems. At the same time, experimental biologists have begun to study dynamics of in vitro systems encapsulated by amphiphilic molecules, opening the door for the development of a new generation of biomimetic systems. In this review, we explore both in vivo and in vitro models of biochemical networks with a special focus on tools that could be applied to the construction of cell-free expression systems. We believe that quantitative studies of complex cellular mechanisms and pathways in synthetic systems can yield important insights into what makes cells different from conventional chemical systems.

  18. Synthetic Biology Outside the Cell: Linking Computational Tools to Cell-Free Systems

    International Nuclear Information System (INIS)

    Lewis, Daniel D.; Villarreal, Fernando D.; Wu, Fan; Tan, Cheemeng

    2014-01-01

    As mathematical models become more commonly integrated into the study of biology, a common language for describing biological processes is manifesting. Many tools have emerged for the simulation of in vivo synthetic biological systems, with only a few examples of prominent work done on predicting the dynamics of cell-free synthetic systems. At the same time, experimental biologists have begun to study dynamics of in vitro systems encapsulated by amphiphilic molecules, opening the door for the development of a new generation of biomimetic systems. In this review, we explore both in vivo and in vitro models of biochemical networks with a special focus on tools that could be applied to the construction of cell-free expression systems. We believe that quantitative studies of complex cellular mechanisms and pathways in synthetic systems can yield important insights into what makes cells different from conventional chemical systems.

  19. An efficient descriptor model for designing materials for solar cells

    Science.gov (United States)

    Alharbi, Fahhad H.; Rashkeev, Sergey N.; El-Mellouhi, Fedwa; Lüthi, Hans P.; Tabet, Nouar; Kais, Sabre

    2015-11-01

    An efficient descriptor model for fast screening of potential materials for solar cell applications is presented. It works for both excitonic and non-excitonic solar cells materials, and in addition to the energy gap it includes the absorption spectrum (α(E)) of the material. The charge transport properties of the explored materials are modelled using the characteristic diffusion length (Ld) determined for the respective family of compounds. The presented model surpasses the widely used Scharber model developed for bulk heterojunction solar cells. Using published experimental data, we show that the presented model is more accurate in predicting the achievable efficiencies. To model both excitonic and non-excitonic systems, two different sets of parameters are used to account for the different modes of operation. The analysis of the presented descriptor model clearly shows the benefit of including α(E) and Ld in view of improved screening results.

  20. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff

    2010-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  1. A cost-emission model for fuel cell/PV/battery hybrid energy system in the presence of demand response program: ε-constraint method and fuzzy satisfying approach

    International Nuclear Information System (INIS)

    Nojavan, Sayyad; Majidi, Majid; Najafi-Ghalelou, Afshin; Ghahramani, Mehrdad; Zare, Kazem

    2017-01-01

    Highlights: • Cost-emission performance of PV/battery/fuel cell hybrid energy system is studied. • Multi-objective optimization model for cost-emission performance is proposed. • ε-constraint method is proposed to produce Pareto solutions of multi-objective model. • Fuzzy satisfying approach selected the best optimal solution from Pareto solutions. • Demand response program is proposed to reduce both cost and emission. - Abstract: Optimal operation of hybrid energy systems is a big challenge in power systems. Nowadays, in addition to the optimum performance of energy systems, their pollution issue has been a hot topic between researchers. In this paper, a multi-objective model is proposed for economic and environmental operation of a battery/fuel cell/photovoltaic (PV) hybrid energy system in the presence of demand response program (DRP). In the proposed paper, the first objective function is minimization of total cost of hybrid energy system. The second objective function is minimization of total CO_2 emission which is in conflict with the first objective function. So, a multi-objective optimization model is presented to model the hybrid system’s optimal and environmental performance problem with considering DRP. The proposed multi-objective model is solved by ε-constraint method and then fuzzy satisfying technique is employed to select the best possible solution. Also, positive effects of DRP on the economic and environmental performance of hybrid system are analyzed. A mixed-integer linear program is used to simulate the proposed model and the obtained results are compared with weighted sum approach to show the effectiveness of proposed method.

  2. Feedback dynamics and cell function: Why systems biology is called Systems Biology.

    Science.gov (United States)

    Wolkenhauer, Olaf; Mesarovic, Mihajlo

    2005-05-01

    A new paradigm, like Systems Biology, should challenge the way research has been conducted previously. This Opinion article aims to present Systems Biology, not as the application of engineering principles to biology but as a merger of systems- and control theory with molecular- and cell biology. In our view, the central dogma of Systems Biology is that it is system dynamics that gives rise to the functioning and function of cells. The concepts of feedback regulation and control of pathways and the coordination of cell function are emphasized as an important area of Systems Biology research. The hurdles and risks for this area are discussed from the perspective of dynamic pathway modelling. Most of all, the aim of this article is to promote mathematical modelling and simulation as a part of molecular- and cell biology. Systems Biology is a success if it is widely accepted that there is nothing more practical than a good theory.

  3. ASN reputation system model

    Science.gov (United States)

    Hutchinson, Steve; Erbacher, Robert F.

    2015-05-01

    Network security monitoring is currently challenged by its reliance on human analysts and the inability for tools to generate indications and warnings for previously unknown attacks. We propose a reputation system based on IP address set membership within the Autonomous System Number (ASN) system. Essentially, a metric generated based on the historic behavior, or misbehavior, of nodes within a given ASN can be used to predict future behavior and provide a mechanism to locate network activity requiring inspection. This will provide reinforcement of notifications and warnings and lead to inspection for ASNs known to be problematic even if initial inspection leads to interpretation of the event as innocuous. We developed proof of concept capabilities to generate the IP address to ASN set membership and analyze the impact of the results. These results clearly show that while some ASNs are one-offs with individual or small numbers of misbehaving IP addresses, there are definitive ASNs with a history of long term and wide spread misbehaving IP addresses. These ASNs with long histories are what we are especially interested in and will provide an additional correlation metric for the human analyst and lead to new tools to aid remediation of these IP address blocks.

  4. A Good Neighborhood for Cells: Bioreactor Demonstration System (BDS-05)

    Science.gov (United States)

    Chung, Leland W. K.; Goodwin, Thomas J. (Technical Monitor)

    2002-01-01

    Good neighborhoods help you grow. As with a city, the lives of a cell are governed by its neighborhood connections Connections that do not work are implicated in a range of diseases. One of those connections - between prostate cancer and bone cells - will be studied on STS-107 using the Bioreactor Demonstration System (BDS-05). To improve the prospects for finding novel therapies, and to identify biomarkers that predict disease progression, scientists need tissue models that behave the same as metastatic or spreading cancer. This is one of several NASA-sponsored lines of cell science research that use the microgravity environment of orbit in an attempt to grow lifelike tissue models for health research. As cells replicate, they "self associate" to form a complex matrix of collagens, proteins, fibers, and other structures. This highly evolved microenvironment tells each cell who is next door, how it should grow arid into what shapes, and how to respond to bacteria, wounds, and other stimuli. Studying these mechanisms outside the body is difficult because cells do not easily self-associate outside a natural environment. Most cell cultures produce thin, flat specimens that offer limited insight into how cells work together. Ironically, growing cell cultures in the microgravity of space produces cell assemblies that more closely resemble what is found in bodies on Earth. NASA's Bioreactor comprises a miniature life support system and a rotating vessel containing cell specimens in a nutrient medium. Orbital BDS experiments that cultured colon and prostate cancers have been highly promising.

  5. PEM fuel cell monitoring system

    Science.gov (United States)

    Meltser, Mark Alexander; Grot, Stephen Andreas

    1998-01-01

    Method and apparatus for monitoring the performance of H.sub.2 --O.sub.2 PEM fuel cells. Outputs from a cell/stack voltage monitor and a cathode exhaust gas H.sub.2 sensor are corrected for stack operating conditions, and then compared to predetermined levels of acceptability. If certain unacceptable conditions coexist, an operator is alerted and/or corrective measures are automatically undertaken.

  6. Cheap electricity with autonomous solar cell systems

    International Nuclear Information System (INIS)

    Ouwens, C.D.

    1993-01-01

    A comparison has been made between the costs of an autonomous solar cell system and a centralized electricity supply system. In both cases investment costs are the main issue. It is shown that for households in densely populated sunny areas, the use of autonomous solar cell systems is - even with today's market prices - only as expensive or even cheaper than a grid connection, as long as efficient electric appliances are used. The modular nature of solar cell systems makes it possible to start with any number of appliances, depending on the amount of money available to be spent. (author)

  7. Characterization of NK cells in mouse models of systemic lupus erythematosus and of the role of the p85β pi3k subunit in NKG2D signaling in NK cells

    OpenAIRE

    Spada, Roberto

    2013-01-01

    Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 22-11-2013 Natural killer (NK) cells are large granular lymphocytes that play an important part as a link between the innate and adaptive immune systems. Various autoimmune diseases are correlated with alterations in the activity of NK cells; nonetheless, their role in the pathogenesis of systemic lupus erythematosus (SLE), a complex multi-factorial...

  8. Retinal Cell Degeneration in Animal Models

    Directory of Open Access Journals (Sweden)

    Masayuki Niwa

    2016-01-01

    Full Text Available The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced, autoimmune (experimental autoimmune encephalomyelitis, mechanical stress (optic nerve crush-induced, light-induced and ischemia (transient retinal ischemia-induced. The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insight into the underlying mechanisms of the disease, and will facilitate the development of novel effective therapeutic drugs to treat retinal cell damage.

  9. LG Solid Oxide Fuel Cell (SOFC) Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Haberman, Ben [LG Fuel Cell Systems Inc., North Canton, OH (United States); Martinez-Baca, Carlos [LG Fuel Cell Systems Inc., North Canton, OH (United States); Rush, Greg [LG Fuel Cell Systems Inc., North Canton, OH (United States)

    2013-05-31

    This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.

  10. Cancer stem cells of the digestive system.

    Science.gov (United States)

    Colvin, Hugh S; Nishida, Naohiro; Koseki, Jun; Konno, Masamitsu; Kawamoto, Koichi; Tsunekuni, Kenta; Doki, Yuichiro; Mori, Masaki; Ishii, Hideshi

    2014-12-01

    Stem cells of the digestive system are ideal in many ways for research, given they are abundant, highly proliferative and have a uniform structural arrangement. This in turn has enormously aided the research of cancer stem cells of the digestive system, which is now shaping our understanding of cancer stem cells. In this review, the recent advances in the understanding of cancer stem cells of the digestive system have been summarized, including aspects such as their identification, origin, cell-cycle dormancy, relationship with epithelial-mesenchymal transition, cellular metabolism and the underlying molecular mechanisms. Newly acquired knowledge concerning cancer stem cells have led to the development of novel cancer therapeutics with provisional yet encouraging results. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. On a poroviscoelastic model for cell crawling

    KAUST Repository

    Kimpton, L. S.; Whiteley, J. P.; Waters, S. L.; Oliver, J. M.

    2014-01-01

    -convected Maxwell model and demonstrate that even the simplest of two-phase, viscoelastic models displays features relevant to cell motility. We also show care must be exercised in choosing parameters for such models as a poor choice can lead to an ill-posed problem

  12. Effect of amino acid supplementation on titer and glycosylation distribution in hybridoma cell cultures-Systems biology-based interpretation using genome-scale metabolic flux balance model and multivariate data analysis.

    Science.gov (United States)

    Reimonn, Thomas M; Park, Seo-Young; Agarabi, Cyrus D; Brorson, Kurt A; Yoon, Seongkyu

    2016-09-01

    Genome-scale flux balance analysis (FBA) is a powerful systems biology tool to characterize intracellular reaction fluxes during cell cultures. FBA estimates intracellular reaction rates by optimizing an objective function, subject to the constraints of a metabolic model and media uptake/excretion rates. A dynamic extension to FBA, dynamic flux balance analysis (DFBA), can calculate intracellular reaction fluxes as they change during cell cultures. In a previous study by Read et al. (2013), a series of informed amino acid supplementation experiments were performed on twelve parallel murine hybridoma cell cultures, and this data was leveraged for further analysis (Read et al., Biotechnol Prog. 2013;29:745-753). In order to understand the effects of media changes on the model murine hybridoma cell line, a systems biology approach is applied in the current study. Dynamic flux balance analysis was performed using a genome-scale mouse metabolic model, and multivariate data analysis was used for interpretation. The calculated reaction fluxes were examined using partial least squares and partial least squares discriminant analysis. The results indicate media supplementation increases product yield because it raises nutrient levels extending the growth phase, and the increased cell density allows for greater culture performance. At the same time, the directed supplementation does not change the overall metabolism of the cells. This supports the conclusion that product quality, as measured by glycoform assays, remains unchanged because the metabolism remains in a similar state. Additionally, the DFBA shows that metabolic state varies more at the beginning of the culture but less by the middle of the growth phase, possibly due to stress on the cells during inoculation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1163-1173, 2016. © 2016 American Institute of Chemical Engineers.

  13. Stochastic Modelling of Energy Systems

    DEFF Research Database (Denmark)

    Andersen, Klaus Kaae

    2001-01-01

    is that the model structure has to be adequate for practical applications, such as system simulation, fault detection and diagnosis, and design of control strategies. This also reflects on the methods used for identification of the component models. The main result from this research is the identification......In this thesis dynamic models of typical components in Danish heating systems are considered. Emphasis is made on describing and evaluating mathematical methods for identification of such models, and on presentation of component models for practical applications. The thesis consists of seven...... research papers (case studies) together with a summary report. Each case study takes it's starting point in typical heating system components and both, the applied mathematical modelling methods and the application aspects, are considered. The summary report gives an introduction to the scope...

  14. Distribution system modeling and analysis

    CERN Document Server

    Kersting, William H

    2001-01-01

    For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that allow engineers to simulate, analyze, and optimize distribution systems. Powerful as these programs are, however, without a real understanding of the operating characteristics of a distribution system, engineers using the programs can easily make serious errors in their designs and operating procedures. Distribution System Modeling and Analysis helps prevent those errors. It gives readers a basic understanding of the modeling and operating characteristics of the major components of a distribution system. One by one, the author develops and analyzes each component as a stand-alone element, then puts them all together to analyze a distribution system comprising the various shunt and series devices for power-flow and short-circuit studies. He includes the derivation of all models and includes many num...

  15. Water reactive hydrogen fuel cell power system

    Science.gov (United States)

    Wallace, Andrew P; Melack, John M; Lefenfeld, Michael

    2014-01-21

    A water reactive hydrogen fueled power system includes devices and methods to combine reactant fuel materials and aqueous solutions to generate hydrogen. The generated hydrogen is converted in a fuel cell to provide electricity. The water reactive hydrogen fueled power system includes a fuel cell, a water feed tray, and a fuel cartridge to generate power for portable power electronics. The removable fuel cartridge is encompassed by the water feed tray and fuel cell. The water feed tray is refillable with water by a user. The water is then transferred from the water feed tray into a fuel cartridge to generate hydrogen for the fuel cell which then produces power for the user.

  16. A Systems Model of Parkinson's Disease Using Biochemical Systems Theory.

    Science.gov (United States)

    Sasidharakurup, Hemalatha; Melethadathil, Nidheesh; Nair, Bipin; Diwakar, Shyam

    2017-08-01

    Parkinson's disease (PD), a neurodegenerative disorder, affects millions of people and has gained attention because of its clinical roles affecting behaviors related to motor and nonmotor symptoms. Although studies on PD from various aspects are becoming popular, few rely on predictive systems modeling approaches. Using Biochemical Systems Theory (BST), this article attempts to model and characterize dopaminergic cell death and understand pathophysiology of progression of PD. PD pathways were modeled using stochastic differential equations incorporating law of mass action, and initial concentrations for the modeled proteins were obtained from literature. Simulations suggest that dopamine levels were reduced significantly due to an increase in dopaminergic quinones and 3,4-dihydroxyphenylacetaldehyde (DOPAL) relating to imbalances compared to control during PD progression. Associating to clinically observed PD-related cell death, simulations show abnormal parkin and reactive oxygen species levels with an increase in neurofibrillary tangles. While relating molecular mechanistic roles, the BST modeling helps predicting dopaminergic cell death processes involved in the progression of PD and provides a predictive understanding of neuronal dysfunction for translational neuroscience.

  17. On a poroviscoelastic model for cell crawling

    KAUST Repository

    Kimpton, L. S.

    2014-02-08

    In this paper a minimal, one-dimensional, two-phase, viscoelastic, reactive, flow model for a crawling cell is presented. Two-phase models are used with a variety of constitutive assumptions in the literature to model cell motility. We use an upper-convected Maxwell model and demonstrate that even the simplest of two-phase, viscoelastic models displays features relevant to cell motility. We also show care must be exercised in choosing parameters for such models as a poor choice can lead to an ill-posed problem. A stability analysis reveals that the initially stationary, spatially uniform strip of cytoplasm starts to crawl in response to a perturbation which breaks the symmetry of the network volume fraction or network stress. We also demonstrate numerically that there is a steady travelling-wave solution in which the crawling velocity has a bell-shaped dependence on adhesion strength, in agreement with biological observation.

  18. A MODEL FOR POSTRADIATION STEM CELL KINETICS,

    Science.gov (United States)

    In polycythemic rats observed for 17 days postradiation (300 R, 250 KVP X-rays) it was noted that stem cell release diminished to 8 percent of the...correlate these findings with a kinetic model of erythropoiesis. It was suggested that the initial depression in stem cell release might be due to cellular

  19. Glucose transport machinery reconstituted in cell models.

    Science.gov (United States)

    Hansen, Jesper S; Elbing, Karin; Thompson, James R; Malmstadt, Noah; Lindkvist-Petersson, Karin

    2015-02-11

    Here we demonstrate the production of a functioning cell model by formation of giant vesicles reconstituted with the GLUT1 glucose transporter and a glucose oxidase and hydrogen peroxidase linked fluorescent reporter internally. Hence, a simplified artificial cell is formed that is able to take up glucose and process it.

  20. Spatial Modeling Tools for Cell Biology

    National Research Council Canada - National Science Library

    Przekwas, Andrzej; Friend, Tom; Teixeira, Rodrigo; Chen, Z. J; Wilkerson, Patrick

    2006-01-01

    .... Scientific potentials and military relevance of computational biology and bioinformatics have inspired DARPA/IPTO's visionary BioSPICE project to develop computational framework and modeling tools for cell biology...

  1. Cytoview: Development of a cell modelling framework

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    is an important aspect of cell modelling. ... 1Supercomputer Education and Research Centreand 2Bioinformatics Centre, Indian Institute ... Important aspects in each panel are listed. ... subsumption relationship, in which the child term is a more.

  2. A flexible multipurpose model for normal and transient cell kinetics

    International Nuclear Information System (INIS)

    Toivonen, Harri.

    1979-07-01

    The internal hypothetical compartments within the different phases of the cell cycle have been adopted as the basis of models dealing with various specific problems in cell kinetics. This approach was found to be of more general validity, extending from expanding cell populations to complex maturation processes. The differential equations describing the system were solved with an effective, commercially available library subroutine. Special attention was devoted to analysis of transient and feedback kinetics of cell populations encountered in diverse environmental and exposure conditions, for instance in cases of wounding and radiation damage. (author)

  3. Data management system performance modeling

    Science.gov (United States)

    Kiser, Larry M.

    1993-01-01

    This paper discusses analytical techniques that have been used to gain a better understanding of the Space Station Freedom's (SSF's) Data Management System (DMS). The DMS is a complex, distributed, real-time computer system that has been redesigned numerous times. The implications of these redesigns have not been fully analyzed. This paper discusses the advantages and disadvantages for static analytical techniques such as Rate Monotonic Analysis (RMA) and also provides a rationale for dynamic modeling. Factors such as system architecture, processor utilization, bus architecture, queuing, etc. are well suited for analysis with a dynamic model. The significance of performance measures for a real-time system are discussed.

  4. Interactions of Model Cell Membranes with Nanoparticles

    Science.gov (United States)

    D'Angelo, S. M.; Camesano, T. A.; Nagarajan, R.

    2011-12-01

    The same properties that give nanoparticles their enhanced function, such as high surface area, small size, and better conductivity, can also alter the cytotoxicity of nanomaterials. Ultimately, many of these nanomaterials will be released into the environment, and can cause cytotoxic effects to environmental bacteria, aquatic organisms, and humans. Previous results from our laboratory suggest that nanoparticles can have a detrimental effect on cells, depending on nanoparticle size. It is our goal to characterize the properties of nanomaterials that can result in membrane destabilization. We tested the effects of nanoparticle size and chemical functionalization on nanoparticle-membrane interactions. Gold nanoparticles at 2, 5,10, and 80 nm were investigated, with a concentration of 1.1x1010 particles/mL. Model cell membranes were constructed of of L-α-phosphatidylcholine (egg PC), which has negatively charged lipid headgroups. A quartz crystal microbalance with dissipation (QCM-D) was used to measure frequency changes at different overtones, which were related to mass changes corresponding to nanoparticle interaction with the model membrane. In QCM-D, a lipid bilayer is constructed on a silicon dioxide crystal. The crystals, oscillate at different harmonic frequencies depending upon changes in mass or energy dissipation. When mass is added to the crystal surface, such as through addition of a lipid vesicle solution, the frequency change decreases. By monitoring the frequency and dissipation, we could verify that a supported lipid bilayer (SLB) formed on the silica surface. After formation of the SLB, the nanoparticles can be added to the system, and the changes in frequency and dissipation are monitored in order to build a mechanistic understanding of nanoparticle-cell membrane interactions. For all of the smaller nanoparticles (2, 5, and 10 nm), nanoparticle addition caused a loss of mass from the lipid bilayer, which appears to be due to the formation of holes

  5. Fuzzy Logic Based Control of Power of PEM Fuel Cell System for Residential Application

    Directory of Open Access Journals (Sweden)

    Khaled MAMMAR

    2009-07-01

    Full Text Available This paper presents a dynamic model of Fuel cell system for residential power generation. The models proposed include a fuel cell stack model, reformer model and DC/AC inverter model. Furthermore a fuzzy logic (FLC controller is used to control active power of PEM fuel cell system. The controller modifies the hydrogen flow feedback from the terminal load. Simulation results confirmed the high performance capability of the fuzzy logic controller to control power generation.

  6. An Automatic Indirect Immunofluorescence Cell Segmentation System

    Directory of Open Access Journals (Sweden)

    Yung-Kuan Chan

    2014-01-01

    Full Text Available Indirect immunofluorescence (IIF with HEp-2 cells has been used for the detection of antinuclear autoantibodies (ANA in systemic autoimmune diseases. The ANA testing allows us to scan a broad range of autoantibody entities and to describe them by distinct fluorescence patterns. Automatic inspection for fluorescence patterns in an IIF image can assist physicians, without relevant experience, in making correct diagnosis. How to segment the cells from an IIF image is essential in developing an automatic inspection system for ANA testing. This paper focuses on the cell detection and segmentation; an efficient method is proposed for automatically detecting the cells with fluorescence pattern in an IIF image. Cell culture is a process in which cells grow under control. Cell counting technology plays an important role in measuring the cell density in a culture tank. Moreover, assessing medium suitability, determining population doubling times, and monitoring cell growth in cultures all require a means of quantifying cell population. The proposed method also can be used to count the cells from an image taken under a fluorescence microscope.

  7. Model systems in photosynthesis research

    International Nuclear Information System (INIS)

    Katz, J.J.; Hindman, J.C.

    1981-01-01

    After a general discussion of model studies in photosynthesis research, three recently developed model systems are described. The current status of covalently linked chlorophyll pairs as models for P700 and P865 is first briefly reviewed. Mg-tris(pyrochlorophyllide)1,1,1-tris(hydroxymethyl) ethane triester in its folded configuration is then discussed as a rudimentary antenna-photoreaction center model. Finally, self-assembled chlorophyll systems that contain a mixture of monomeric, oligomeric and special pair chlorophyll are shown to have fluorescence emission characteristics that resemble thoe of intact Tribonema aequale at room temperature in that both show fluorescence emission at 675 and 695 nm. In the self-assembled systems the wavelength of the emitted fluorescence depends on the wavelength of excitation, arguing that energy transfer between different chlorophyll species in these systems may be more complex than previously suspected

  8. Modelling of robotic work cells using agent based-approach

    Science.gov (United States)

    Sękala, A.; Banaś, W.; Gwiazda, A.; Monica, Z.; Kost, G.; Hryniewicz, P.

    2016-08-01

    In the case of modern manufacturing systems the requirements, both according the scope and according characteristics of technical procedures are dynamically changing. This results in production system organization inability to keep up with changes in a market demand. Accordingly, there is a need for new design methods, characterized, on the one hand with a high efficiency and on the other with the adequate level of the generated organizational solutions. One of the tools that could be used for this purpose is the concept of agent systems. These systems are the tools of artificial intelligence. They allow assigning to agents the proper domains of procedures and knowledge so that they represent in a self-organizing system of an agent environment, components of a real system. The agent-based system for modelling robotic work cell should be designed taking into consideration many limitations considered with the characteristic of this production unit. It is possible to distinguish some grouped of structural components that constitute such a system. This confirms the structural complexity of a work cell as a specific production system. So it is necessary to develop agents depicting various aspects of the work cell structure. The main groups of agents that are used to model a robotic work cell should at least include next pattern representatives: machine tool agents, auxiliary equipment agents, robots agents, transport equipment agents, organizational agents as well as data and knowledge bases agents. In this way it is possible to create the holarchy of the agent-based system.

  9. Mobility Models for Systems Evaluation

    Science.gov (United States)

    Musolesi, Mirco; Mascolo, Cecilia

    Mobility models are used to simulate and evaluate the performance of mobile wireless systems and the algorithms and protocols at the basis of them. The definition of realistic mobility models is one of the most critical and, at the same time, difficult aspects of the simulation of applications and systems designed for mobile environments. There are essentially two possible types of mobility patterns that can be used to evaluate mobile network protocols and algorithms by means of simulations: traces and synthetic models [130]. Traces are obtained by means of measurements of deployed systems and usually consist of logs of connectivity or location information, whereas synthetic models are mathematical models, such as sets of equations, which try to capture the movement of the devices.

  10. Stochastic Models of Polymer Systems

    Science.gov (United States)

    2016-01-01

    Distribution Unlimited Final Report: Stochastic Models of Polymer Systems The views, opinions and/or findings contained in this report are those of the...ADDRESS. Princeton University PO Box 0036 87 Prospect Avenue - 2nd floor Princeton, NJ 08544 -2020 14-Mar-2014 ABSTRACT Number of Papers published in...peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: Stochastic Models of Polymer Systems Report Title

  11. Immunoregulation of NKT Cells in Systemic Lupus Erythematosus.

    Science.gov (United States)

    Chen, Junwei; Wu, Meng; Wang, Jing; Li, Xiaofeng

    2015-01-01

    Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease with different variety of clinical manifestations. Natural killer T (NKT) cells are innate lymphocytes that play a regulatory role during broad range of immune responses. A number of studies demonstrated that the quantity and quality of invariant NKT (iNKT) cells showed marked defects in SLE patients in comparison to healthy controls. This finding suggests that iNKT cells may play a regulatory role in the occurrence and development of this disease. In this review, we mainly summarized the most recent findings about the behavior of NKT cells in SLE patients and mouse models, as well as how NKT cells affect the proportion of T helper cells and the production of autoreactive antibodies in the progress of SLE. This will help people better understand the role of NKT cells in the development of SLE and improve the therapy strategy.

  12. Mathematical modeling of solid oxide fuel cells

    Science.gov (United States)

    Lu, Cheng-Yi; Maloney, Thomas M.

    1988-01-01

    Development of predictive techniques, with regard to cell behavior, under various operating conditions is needed to improve cell performance, increase energy density, reduce manufacturing cost, and to broaden utilization of various fuels. Such technology would be especially beneficial for the solid oxide fuel cells (SOFC) at it early demonstration stage. The development of computer models to calculate the temperature, CD, reactant distributions in the tubular and monolithic SOFCs. Results indicate that problems of nonuniform heat generation and fuel gas depletion in the tubular cell module, and of size limitions in the monolithic (MOD 0) design may be encountered during FC operation.

  13. A Systems Approach Reveals MAVS Signaling in Myeloid Cells as Critical for Resistance to Ebola Virus in Murine Models of Infection

    Directory of Open Access Journals (Sweden)

    Mukta Dutta

    2017-01-01

    Full Text Available The unprecedented 2013–2016 outbreak of Ebola virus (EBOV resulted in over 11,300 human deaths. Host resistance to RNA viruses requires RIG-I-like receptor (RLR signaling through the adaptor protein, mitochondrial antiviral signaling protein (MAVS, but the role of RLR-MAVS in orchestrating anti-EBOV responses in vivo is not known. Here we apply a systems approach to MAVS−/− mice infected with either wild-type or mouse-adapted EBOV. MAVS controlled EBOV replication through the expression of IFNα, regulation of inflammatory responses in the spleen, and prevention of cell death in the liver, with macrophages implicated as a major cell type influencing host resistance. A dominant role for RLR signaling in macrophages was confirmed following conditional MAVS deletion in LysM+ myeloid cells. These findings reveal tissue-specific MAVS-dependent transcriptional pathways associated with resistance to EBOV, and they demonstrate that EBOV adaptation to cause disease in mice involves changes in two distinct events, RLR-MAVS antagonism and suppression of RLR-independent IFN-I responses.

  14. A Systems Approach Reveals MAVS Signaling in Myeloid Cells as Critical for Resistance to Ebola Virus in Murine Models of Infection.

    Science.gov (United States)

    Dutta, Mukta; Robertson, Shelly J; Okumura, Atsushi; Scott, Dana P; Chang, Jean; Weiss, Jeffrey M; Sturdevant, Gail L; Feldmann, Friederike; Haddock, Elaine; Chiramel, Abhilash I; Ponia, Sanket S; Dougherty, Jonathan D; Katze, Michael G; Rasmussen, Angela L; Best, Sonja M

    2017-01-17

    The unprecedented 2013-2016 outbreak of Ebola virus (EBOV) resulted in over 11,300 human deaths. Host resistance to RNA viruses requires RIG-I-like receptor (RLR) signaling through the adaptor protein, mitochondrial antiviral signaling protein (MAVS), but the role of RLR-MAVS in orchestrating anti-EBOV responses in vivo is not known. Here we apply a systems approach to MAVS -/- mice infected with either wild-type or mouse-adapted EBOV. MAVS controlled EBOV replication through the expression of IFNα, regulation of inflammatory responses in the spleen, and prevention of cell death in the liver, with macrophages implicated as a major cell type influencing host resistance. A dominant role for RLR signaling in macrophages was confirmed following conditional MAVS deletion in LysM+ myeloid cells. These findings reveal tissue-specific MAVS-dependent transcriptional pathways associated with resistance to EBOV, and they demonstrate that EBOV adaptation to cause disease in mice involves changes in two distinct events, RLR-MAVS antagonism and suppression of RLR-independent IFN-I responses. Published by Elsevier Inc.

  15. Development of a 3D cell-centered Lagrangian scheme for the numerical modeling of the gas dynamics and hyper-elasticity systems

    International Nuclear Information System (INIS)

    Georges, Gabriel

    2016-01-01

    High Energy Density Physics (HEDP) flows are multi-material flows characterized by strong shock waves and large changes in the domain shape due to rare faction waves. Numerical schemes based on the Lagrangian formalism are good candidates to model this kind of flows since the computational grid follows the fluid motion. This provides accurate results around the shocks as well as a natural tracking of multi-material interfaces and free-surfaces. In particular, cell-centered Finite Volume Lagrangian schemes such as GLACE (Godunov-type Lagrangian scheme Conservative for total Energy) and EUCCLHYD (Explicit Unstructured Cell-Centered Lagrangian Hydrodynamics) provide good results on both the modeling of gas dynamics and elastic-plastic equations. The work produced during this PhD thesis is in continuity with the work of Maire and Nkonga [JCP, 2009] for the hydrodynamic part and the work of Kluth and Despres [JCP, 2010] for the hyper elasticity part. More precisely, the aim of this thesis is to develop robust and accurate methods for the 3D extension of the EUCCLHYD scheme with a second-order extension based on MUSCL (Monotonic Upstream-centered Scheme for Conservation Laws) and GRP (Generalized Riemann Problem) procedures. A particular care is taken on the preservation of symmetries and the monotonicity of the solutions. The scheme robustness and accuracy are assessed on numerous Lagrangian test cases for which the 3D extensions are very challenging. (author) [fr

  16. National Energy Outlook Modelling System

    Energy Technology Data Exchange (ETDEWEB)

    Volkers, C.M. [ECN Policy Studies, Petten (Netherlands)

    2013-12-15

    For over 20 years, the Energy research Centre of the Netherlands (ECN) has been developing the National Energy Outlook Modelling System (NEOMS) for Energy projections and policy evaluations. NEOMS enables 12 energy models of ECN to exchange data and produce consistent and detailed results.

  17. An oscillating dynamic model of collective cells in a monolayer

    Science.gov (United States)

    Lin, Shao-Zhen; Xue, Shi-Lei; Li, Bo; Feng, Xi-Qiao

    2018-03-01

    Periodic oscillations of collective cells occur in the morphogenesis and organogenesis of various tissues and organs. In this paper, an oscillating cytodynamic model is presented by integrating the chemomechanical interplay between the RhoA effector signaling pathway and cell deformation. We show that both an isolated cell and a cell aggregate can undergo spontaneous oscillations as a result of Hopf bifurcation, upon which the system evolves into a limit cycle of chemomechanical oscillations. The dynamic characteristics are tailored by the mechanical properties of cells (e.g., elasticity, contractility, and intercellular tension) and the chemical reactions involved in the RhoA effector signaling pathway. External forces are found to modulate the oscillation intensity of collective cells in the monolayer and to polarize their oscillations along the direction of external tension. The proposed cytodynamic model can recapitulate the prominent features of cell oscillations observed in a variety of experiments, including both isolated cells (e.g., spreading mouse embryonic fibroblasts, migrating amoeboid cells, and suspending 3T3 fibroblasts) and multicellular systems (e.g., Drosophila embryogenesis and oogenesis).

  18. Mathematical modeling of a thermovoltaic cell

    Science.gov (United States)

    White, Ralph E.; Kawanami, Makoto

    1992-01-01

    A new type of battery named 'Vaporvolt' cell is in the early stage of its development. A mathematical model of a CuO/Cu 'Vaporvolt' cell is presented that can be used to predict the potential and the transport behavior of the cell during discharge. A sensitivity analysis of the various transport and electrokinetic parameters indicates which parameters have the most influence on the predicted energy and power density of the 'Vaporvolt' cell. This information can be used to decide which parameters should be optimized or determined more accurately through further modeling or experimental studies. The optimal thicknesses of electrodes and separator, the concentration of the electrolyte, and the current density are determined by maximizing the power density. These parameter sensitivities and optimal design parameter values will help in the development of a better CuO/Cu 'Vaporvolt' cell.

  19. SOLID OXIDE FUEL CELL HYBRID SYSTEM FOR DISTRIBUTED POWER GENERATION

    Energy Technology Data Exchange (ETDEWEB)

    Faress Rahman; Nguyen Minh

    2003-07-01

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC during the January 2003 to June 2003 reporting period under Cooperative Agreement DE-FC26-01NT40779 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Solid Oxide Fuel Cell Hybrid System for Distributed Power Generation''. The main objective of this project is to develop and demonstrate the feasibility of a highly efficient hybrid system integrating a planar Solid Oxide Fuel Cell (SOFC) and a micro-turbine. In addition, an activity included in this program focuses on the development of an integrated coal gasification fuel cell system concept based on planar SOFC technology. This report summarizes the results obtained to date on: System performance analysis and model optimization; Reliability and cost model development; System control including dynamic model development; Heat exchanger material tests and life analysis; Pressurized SOFC evaluation; and Pre-baseline system definition for coal gasification fuel cell system concept.

  20. Aerodynamic and Mechanical System Modelling

    DEFF Research Database (Denmark)

    Jørgensen, Martin Felix

    This thesis deals with mechanical multibody-systems applied to the drivetrain of a 500 kW wind turbine. Particular focus has been on gearbox modelling of wind turbines. The main part of the present project involved programming multibody systems to investigate the connection between forces, moments...

  1. Experimental Modeling of Dynamic Systems

    DEFF Research Database (Denmark)

    Knudsen, Morten Haack

    2006-01-01

    An engineering course, Simulation and Experimental Modeling, has been developed that is based on a method for direct estimation of physical parameters in dynamic systems. Compared with classical system identification, the method appears to be easier to understand, apply, and combine with physical...

  2. Amoebal endosymbiont Parachlamydia acanthamoebae Bn9 can grow in immortal human epithelial HEp-2 cells at low temperature; an in vitro model system to study chlamydial evolution.

    Science.gov (United States)

    Yamane, Chikayo; Yamazaki, Tomohiro; Nakamura, Shinji; Matsuo, Junji; Ishida, Kasumi; Yamazaki, Sumire; Oguri, Satoshi; Shouji, Natsumi; Hayashi, Yasuhiro; Yoshida, Mitsutaka; Yimin; Yamaguchi, Hiroyuki

    2015-01-01

    Ancient chlamydiae diverged into pathogenic and environmental chlamydiae 0.7-1.4 billion years ago. However, how pathogenic chlamydiae adapted to mammalian cells that provide a stable niche at approximately 37 °C, remains unknown, although environmental chlamydiae have evolved as endosymbionts of lower eukaryotes in harsh niches of relatively low temperatures. Hence, we assessed whether an environmental chlamydia, Parachlamydia Bn9, could grow in human HEp-2 cells at a low culture temperature of 30 °C. The assessment of inclusion formation by quantitative RT-PCR revealed that the numbers of bacterial inclusion bodies and the transcription level of 16SrRNA significantly increased after culture at 30 °C compared to at 37 °C. Confocal microscopy showed that the bacteria were located close to HEp-2 nuclei and were actively replicative. Transmission electron microscopy also revealed replicating bacteria consisting of reticular bodies, but with a few elementary bodies. Cytochalasin D and rifampicin inhibited inclusion formation. Lactacystin slightly inhibited bacterial inclusion formation. KEGG analysis using a draft genome sequence of the bacteria revealed that it possesses metabolic pathways almost identical to those of pathogenic chlamydia. Interestingly, comparative genomic analysis with pathogenic chlamydia revealed that the Parachlamydia similarly possess the genes encoding Type III secretion system, but lacking genes encoding inclusion membrane proteins (IncA to G) required for inclusion maturation. Taken together, we conclude that ancient chlamydiae had the potential to grow in human cells, but overcoming the thermal gap was a critical event for chlamydial adaptation to human cells.

  3. Spatial organization of mesenchymal stem cells in vitro--results from a new individual cell-based model with podia.

    Directory of Open Access Journals (Sweden)

    Martin Hoffmann

    Full Text Available Therapeutic application of mesenchymal stem cells (MSC requires their extensive in vitro expansion. MSC in culture typically grow to confluence within a few weeks. They show spindle-shaped fibroblastoid morphology and align to each other in characteristic spatial patterns at high cell density. We present an individual cell-based model (IBM that is able to quantitatively describe the spatio-temporal organization of MSC in culture. Our model substantially improves on previous models by explicitly representing cell podia and their dynamics. It employs podia-generated forces for cell movement and adjusts cell behavior in response to cell density. At the same time, it is simple enough to simulate thousands of cells with reasonable computational effort. Experimental sheep MSC cultures were monitored under standard conditions. Automated image analysis was used to determine the location and orientation of individual cells. Our simulations quantitatively reproduced the observed growth dynamics and cell-cell alignment assuming cell density-dependent proliferation, migration, and morphology. In addition to cell growth on plain substrates our model captured cell alignment on micro-structured surfaces. We propose a specific surface micro-structure that according to our simulations can substantially enlarge cell culture harvest. The 'tool box' of cell migratory behavior newly introduced in this study significantly enhances the bandwidth of IBM. Our approach is capable of accommodating individual cell behavior and collective cell dynamics of a variety of cell types and tissues in computational systems biology.

  4. Microbial Heat Recovery Cell (MHRC) System Concept

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-09-01

    This factsheet describes a project that aimed to develop a microbial heat recovery cell (MHRC) system that combines a microbial reverse electrodialysis technology with waste heat recovery to convert industrial effluents into electricity and hydrogen.

  5. Models to Study NK Cell Biology and Possible Clinical Application.

    Science.gov (United States)

    Zamora, Anthony E; Grossenbacher, Steven K; Aguilar, Ethan G; Murphy, William J

    2015-08-03

    Natural killer (NK) cells are large granular lymphocytes of the innate immune system, responsible for direct targeting and killing of both virally infected and transformed cells. NK cells rapidly recognize and respond to abnormal cells in the absence of prior sensitization due to their wide array of germline-encoded inhibitory and activating receptors, which differs from the receptor diversity found in B and T lymphocytes that is due to the use of recombination-activation gene (RAG) enzymes. Although NK cells have traditionally been described as natural killers that provide a first line of defense prior to the induction of adaptive immunity, a more complex view of NK cells is beginning to emerge, indicating they may also function in various immunoregulatory roles and have the capacity to shape adaptive immune responses. With the growing appreciation for the diverse functions of NK cells, and recent technological advancements that allow for a more in-depth understanding of NK cell biology, we can now begin to explore new ways to manipulate NK cells to increase their clinical utility. In this overview unit, we introduce the reader to various aspects of NK cell biology by reviewing topics ranging from NK cell diversity and function, mouse models, and the roles of NK cells in health and disease, to potential clinical applications. © 2015 by John Wiley & Sons, Inc. Copyright © 2015 John Wiley & Sons, Inc.

  6. Modeling Multi-Level Systems

    CERN Document Server

    Iordache, Octavian

    2011-01-01

    This book is devoted to modeling of multi-level complex systems, a challenging domain for engineers, researchers and entrepreneurs, confronted with the transition from learning and adaptability to evolvability and autonomy for technologies, devices and problem solving methods. Chapter 1 introduces the multi-scale and multi-level systems and highlights their presence in different domains of science and technology. Methodologies as, random systems, non-Archimedean analysis, category theory and specific techniques as model categorification and integrative closure, are presented in chapter 2. Chapters 3 and 4 describe polystochastic models, PSM, and their developments. Categorical formulation of integrative closure offers the general PSM framework which serves as a flexible guideline for a large variety of multi-level modeling problems. Focusing on chemical engineering, pharmaceutical and environmental case studies, the chapters 5 to 8 analyze mixing, turbulent dispersion and entropy production for multi-scale sy...

  7. Pembangunan Model Restaurant Management System

    Directory of Open Access Journals (Sweden)

    Fredy Jingga

    2014-12-01

    Full Text Available Model design for Restaurant Management System aims to help in restaurant business process, where Restaurant Management System (RMS help the waitress and chef could interact each other without paper limitation.  This Restaurant Management System Model develop using Agile Methodology and developed based on PHP Programming Langguage. The database management system is using MySQL. This web-based application model will enable the waitress and the chef to interact in realtime, from the time they accept the customer order until the chef could know what to cook and checklist for the waitress wheter the order is fullfill or not, until the cahsier that will calculate the bill and the payment that they accep from the customer.

  8. A hybrid agent-based approach for modeling microbiological systems.

    Science.gov (United States)

    Guo, Zaiyi; Sloot, Peter M A; Tay, Joc Cing

    2008-11-21

    Models for systems biology commonly adopt Differential Equations or Agent-Based modeling approaches for simulating the processes as a whole. Models based on differential equations presuppose phenomenological intracellular behavioral mechanisms, while models based on Multi-Agent approach often use directly translated, and quantitatively less precise if-then logical rule constructs. We propose an extendible systems model based on a hybrid agent-based approach where biological cells are modeled as individuals (agents) while molecules are represented by quantities. This hybridization in entity representation entails a combined modeling strategy with agent-based behavioral rules and differential equations, thereby balancing the requirements of extendible model granularity with computational tractability. We demonstrate the efficacy of this approach with models of chemotaxis involving an assay of 10(3) cells and 1.2x10(6) molecules. The model produces cell migration patterns that are comparable to laboratory observations.

  9. Direct methanol feed fuel cell and system

    Science.gov (United States)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2009-01-01

    Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous. The fuel cell system also comprises a fuel supplying part including a meter which meters an amount of fuel which is used by the fuel cell, and controls the supply of fuel based on said metering.

  10. Radiobiological modelling with MarCell software

    International Nuclear Information System (INIS)

    Hasan, J.S.; Jones, T.D.

    1996-01-01

    Jones introduced a bone marrow radiation cell kinetics model with great potential for application in the fields of health physics, radiation research, and medicine. However, until recently, only the model developers have been able to apply it because of the complex array of biological and physical assignments needed for evaluation of a particular radiation exposure protocol. The purpose of this article is to illustrate the use of MarCell (MARrow CELL Kinetics) software for MS-DOS, a user-friendly computer implementation of that mathematical model that allows almost anyone with an elementary knowledge of radiation physics and/or medical procedures to apply the model. A hands-on demonstration of the software will be given by guiding the user through evaluation of a medical total body irradiation protocol and a nuclear fallout scenario. A brief overview of the software is given in the Appendix

  11. A mathematical model of cancer cells with phenotypic plasticity

    Directory of Open Access Journals (Sweden)

    Da Zhou

    2015-12-01

    Full Text Available Purpose: The phenotypic plasticity of cancer cells is recently becoming a cutting-edge research area in cancer, which challenges the cellular hierarchy proposed by the conventional cancer stem cell theory. In this study, we establish a mathematical model for describing the phenotypic plasticity of cancer cells, based on which we try to find some salient features that can characterize the dynamic behavior of the phenotypic plasticity especially in comparison to the hierarchical model of cancer cells. Methods: We model cancer as population dynamics composed of different phenotypes of cancer cells. In this model, not only can cancer cells divide (symmetrically and asymmetrically and die, but they can also convert into other cellular phenotypes. According to the Law of Mass Action, the cellular processes can be captured by a system of ordinary differential equations (ODEs. On one hand, we can analyze the long-term stability of the model by applying qualitative method of ODEs. On the other hand, we are also concerned about the short-term behavior of the model by studying its transient dynamics. Meanwhile, we validate our model to the cell-state dynamics in published experimental data.Results: Our results show that the phenotypic plasticity plays important roles in both stabilizing the distribution of different phenotypic mixture and maintaining the cancer stem cells proportion. In particular, the phenotypic plasticity model shows decided advantages over the hierarchical model in predicting the phenotypic equilibrium and cancer stem cells’ overshoot reported in previous biological experiments in cancer cell lines.Conclusion: Since the validity of the phenotypic plasticity paradigm and the conventional cancer stem cell theory is still debated in experimental biology, it is worthy of theoretically searching for good indicators to distinguish the two models through quantitative methods. According to our study, the phenotypic equilibrium and overshoot

  12. MCF-10A-NeoST: A New Cell System for Studying Cell-ECM and Cell-Cell Interactions in Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zantek, Nicole Dodge; Walker-Daniels, Jennifer; Stewart, Jane; Hansen, Rhonda K.; Robinson, Daniel; Miao, Hui; Wang, Bingcheng; Kung, Hsing-Jien; Bissell, Mina J.; Kinch, Michael S.

    2001-08-22

    There is a continuing need for genetically matched cell systems to model cellular behaviors that are frequently observed in aggressive breast cancers. We report here the isolation and initial characterization of a spontaneously arising variant of MCF-10A cells, NeoST, which provides a new model to study cell adhesion and signal transduction in breast cancer. NeoST cells recapitulate important biological and biochemical features of metastatic breast cancer, including anchorage-independent growth, invasiveness in threedimensional reconstituted membranes, loss of E-cadherin expression, and increased tyrosine kinase activity. A comprehensive analysis of tyrosine kinase expression revealed overexpression or functional activation of the Axl, FAK, and EphA2 tyrosine kinases in transformed MCF-10A cells. MCF-10A and these new derivatives provide a genetically matched model to study defects in cell adhesion and signaling that are relevant to cellular behaviors that often typify aggressive breast cancer cells.

  13. Cre-mediated cell ablation contests mast cell contribution in models of antibody- and T cell-mediated autoimmunity.

    Science.gov (United States)

    Feyerabend, Thorsten B; Weiser, Anne; Tietz, Annette; Stassen, Michael; Harris, Nicola; Kopf, Manfred; Radermacher, Peter; Möller, Peter; Benoist, Christophe; Mathis, Diane; Fehling, Hans Jörg; Rodewald, Hans-Reimer

    2011-11-23

    Immunological functions of mast cells remain poorly understood. Studies in Kit mutant mice suggest key roles for mast cells in certain antibody- and T cell-mediated autoimmune diseases. However, Kit mutations affect multiple cell types of both immune and nonimmune origin. Here, we show that targeted insertion of Cre-recombinase into the mast cell carboxypeptidase A3 locus deleted mast cells in connective and mucosal tissues by a genotoxic Trp53-dependent mechanism. Cre-mediated mast cell eradication (Cre-Master) mice had, with the exception of a lack of mast cells and reduced basophils, a normal immune system. Cre-Master mice were refractory to IgE-mediated anaphylaxis, and this defect was rescued by mast cell reconstitution. This mast cell-deficient strain was fully susceptible to antibody-induced autoimmune arthritis and to experimental autoimmune encephalomyelitis. Differences comparing Kit mutant mast cell deficiency models to selectively mast cell-deficient mice call for a systematic re-evaluation of immunological functions of mast cells beyond allergy. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Genome engineering of stem cell organoids for disease modeling.

    Science.gov (United States)

    Sun, Yingmin; Ding, Qiurong

    2017-05-01

    Precision medicine emerges as a new approach that takes into account individual variability. Successful realization of precision medicine requires disease models that are able to incorporate personalized disease information and recapitulate disease development processes at the molecular, cellular and organ levels. With recent development in stem cell field, a variety of tissue organoids can be derived from patient specific pluripotent stem cells and adult stem cells. In combination with the state-of-the-art genome editing tools, organoids can be further engineered to mimic disease-relevant genetic and epigenetic status of a patient. This has therefore enabled a rapid expansion of sophisticated in vitro disease models, offering a unique system for fundamental and biomedical research as well as the development of personalized medicine. Here we summarize some of the latest advances and future perspectives in engineering stem cell organoids for human disease modeling.

  15. Models of complex attitude systems

    DEFF Research Database (Denmark)

    Sørensen, Bjarne Taulo

    search algorithms and structural equation models. The results suggest that evaluative judgments of the importance of production system attributes are generated in a schematic manner, driven by personal value orientations. The effect of personal value orientations was strong and largely unmediated...... that evaluative affect propagates through the system in such a way that the system becomes evaluatively consistent and operates as a schema for the generation of evaluative judgments. In the empirical part of the paper, the causal structure of an attitude system from which people derive their evaluations of pork......Existing research on public attitudes towards agricultural production systems is largely descriptive, abstracting from the processes through which members of the general public generate their evaluations of such systems. The present paper adopts a systems perspective on such evaluations...

  16. Coal Integrated Gasification Fuel Cell System Study

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Wotzak; Chellappa Balan; Faress Rahman; Nguyen Minh

    2003-08-01

    The pre-baseline configuration for an Integrated Gasification Fuel Cell (IGFC) system has been developed. This case uses current gasification, clean-up, gas turbine, and bottoming cycle technologies together with projected large planar Solid Oxide Fuel Cell (SOFC) technology. This pre-baseline case will be used as a basis for identifying the critical factors impacting system performance and the major technical challenges in implementing such systems. Top-level system requirements were used as the criteria to evaluate and down select alternative sub-systems. The top choice subsystems were subsequently integrated to form the pre-baseline case. The down-selected pre-baseline case includes a British Gas Lurgi (BGL) gasification and cleanup sub-system integrated with a GE Power Systems 6FA+e gas turbine and the Hybrid Power Generation Systems planar Solid Oxide Fuel Cell (SOFC) sub-system. The overall efficiency of this system is estimated to be 43.0%. The system efficiency of the pre-baseline system provides a benchmark level for further optimization efforts in this program.

  17. Stirling Engine Dynamic System Modeling

    Science.gov (United States)

    Nakis, Christopher G.

    2004-01-01

    The Thermo-Mechanical systems branch at the Glenn Research Center focuses a large amount time on Stirling engines. These engines will be used on missions where solar power is inefficient, especially in deep space. I work with Tim Regan and Ed Lewandowski who are currently developing and validating a mathematical model for the Stirling engines. This model incorporates all aspects of the system including, mechanical, electrical and thermodynamic components. Modeling is done through Simplorer, a program capable of running simulations of the model. Once created and then proven to be accurate, a model is used for developing new ideas for engine design. My largest specific project involves varying key parameters in the model and quantifying the results. This can all be done relatively trouble-free with the help of Simplorer. Once the model is complete, Simplorer will do all the necessary calculations. The more complicated part of this project is determining which parameters to vary. Finding key parameters depends on the potential for a value to be independently altered in the design. For example, a change in one dimension may lead to a proportional change to the rest of the model, and no real progress is made. Also, the ability for a changed value to have a substantial impact on the outputs of the system is important. Results will be condensed into graphs and tables with the purpose of better communication and understanding of the data. With the changing of these parameters, a more optimal design can be created without having to purchase or build any models. Also, hours and hours of results can be simulated in minutes. In the long run, using mathematical models can save time and money. Along with this project, I have many other smaller assignments throughout the summer. My main goal is to assist in the processes of model development, validation and testing.

  18. A quantitative and dynamic model for plant stem cell regulation.

    Directory of Open Access Journals (Sweden)

    Florian Geier

    Full Text Available Plants maintain pools of totipotent stem cells throughout their entire life. These stem cells are embedded within specialized tissues called meristems, which form the growing points of the organism. The shoot apical meristem of the reference plant Arabidopsis thaliana is subdivided into several distinct domains, which execute diverse biological functions, such as tissue organization, cell-proliferation and differentiation. The number of cells required for growth and organ formation changes over the course of a plants life, while the structure of the meristem remains remarkably constant. Thus, regulatory systems must be in place, which allow for an adaptation of cell proliferation within the shoot apical meristem, while maintaining the organization at the tissue level. To advance our understanding of this dynamic tissue behavior, we measured domain sizes as well as cell division rates of the shoot apical meristem under various environmental conditions, which cause adaptations in meristem size. Based on our results we developed a mathematical model to explain the observed changes by a cell pool size dependent regulation of cell proliferation and differentiation, which is able to correctly predict CLV3 and WUS over-expression phenotypes. While the model shows stem cell homeostasis under constant growth conditions, it predicts a variation in stem cell number under changing conditions. Consistent with our experimental data this behavior is correlated with variations in cell proliferation. Therefore, we investigate different signaling mechanisms, which could stabilize stem cell number despite variations in cell proliferation. Our results shed light onto the dynamic constraints of stem cell pool maintenance in the shoot apical meristem of Arabidopsis in different environmental conditions and developmental states.

  19. Liposome Model Systems to Study the Endosomal Escape of Cell-Penetrating Peptides: Transport across Phospholipid Membranes Induced by a Proton Gradient

    Directory of Open Access Journals (Sweden)

    Fatemeh Madani

    2011-01-01

    Full Text Available Detergent-mediated reconstitution of bacteriorhodopsin (BR into large unilamellar vesicles (LUVs was investigated, and the effects were carefully characterized for every step of the procedure. LUVs were prepared by the extrusion method, and their size and stability were examined by dynamic light scattering. BR was incorporated into the LUVs using the detergent-mediated reconstitution method and octyl glucoside (OG as detergent. The result of measuring pH outside the LUVs suggested that in the presence of light, BR pumps protons from the outside to the inside of the LUVs, creating acidic pH inside the vesicles. LUVs with 20% negatively charged headgroups were used to model endosomes with BR incorporated into the membrane. The fluorescein-labeled cell-penetrating peptide penetratin was entrapped inside these BR-containing LUVs. The light-induced proton pumping activity of BR has allowed us to observe the translocation of fluorescein-labeled penetratin across the vesicle membrane.

  20. Cell-Oriented Modeling of Angiogenesis

    Directory of Open Access Journals (Sweden)

    Diego Guidolin

    2011-01-01

    Full Text Available Due to its significant involvement in various physiological and pathological conditions, angiogenesis (the development of new blood vessels from an existing vasculature represents an important area of the actual biological research and a field in which mathematical modeling proved particularly useful in supporting the experimental work. In this paper, we focus on a specific modeling strategy, known as “cell-centered” approach. This type of mathematical models work at a “mesoscopic scale,” assuming the cell as the natural level of abstraction for computational modeling of development. They treat cells phenomenologically, considering their essential behaviors to study how tissue structure and organization emerge from the collective dynamics of multiple cells. The main contributions of the cell-oriented approach to the study of the angiogenic process will be described. From one side, they have generated “basic science understanding” about the process of capillary assembly during development, growth, and pathology. On the other side, models were also developed supporting “applied biomedical research” for the purpose of identifying new therapeutic targets and clinically relevant approaches for either inhibiting or stimulating angiogenesis.

  1. Cell-oriented modeling of angiogenesis.

    Science.gov (United States)

    Guidolin, Diego; Rebuffat, Piera; Albertin, Giovanna

    2011-01-01

    Due to its significant involvement in various physiological and pathological conditions, angiogenesis (the development of new blood vessels from an existing vasculature) represents an important area of the actual biological research and a field in which mathematical modeling proved particularly useful in supporting the experimental work. In this paper, we focus on a specific modeling strategy, known as "cell-centered" approach. This type of mathematical models work at a "mesoscopic scale," assuming the cell as the natural level of abstraction for computational modeling of development. They treat cells phenomenologically, considering their essential behaviors to study how tissue structure and organization emerge from the collective dynamics of multiple cells. The main contributions of the cell-oriented approach to the study of the angiogenic process will be described. From one side, they have generated "basic science understanding" about the process of capillary assembly during development, growth, and pathology. On the other side, models were also developed supporting "applied biomedical research" for the purpose of identifying new therapeutic targets and clinically relevant approaches for either inhibiting or stimulating angiogenesis.

  2. The Mast Cell, Contact, and Coagulation System Connection in Anaphylaxis

    Directory of Open Access Journals (Sweden)

    Mar Guilarte

    2017-07-01

    Full Text Available Anaphylaxis is the most severe form of allergic reaction, resulting from the effect of mediators and chemotactic substances released by activated cells. Mast cells and basophils are considered key players in IgE-mediated human anaphylaxis. Beyond IgE-mediated activation of mast cells/basophils, further mechanisms are involved in the occurrence of anaphylaxis. New insights into the potential relevance of pathways other than mast cell and basophil degranulation have been unraveled, such as the activation of the contact and the coagulation systems. Mast cell heparin released upon activation provides negatively charged surfaces for factor XII (FXII binding and auto-activation. Activated FXII, the initiating serine protease in both the contact and the intrinsic coagulation system, activates factor XI and prekallikrein, respectively. FXII-mediated bradykinin (BK formation has been proven in the human plasma of anaphylactic patients as well as in experimental models of anaphylaxis. Moreover, the severity of anaphylaxis is correlated with the increase in plasma heparin, BK formation and the intensity of contact system activation. FXII also activates plasminogen in the fibrinolysis system. Mast cell tryptase has been shown to participate in fibrinolysis through plasmin activation and by facilitating the degradation of fibrinogen. Some usual clinical manifestations in anaphylaxis, such as angioedema or hypotension, or other less common, such as metrorrhagia, may be explained by the direct effect of the activation of the coagulation and contact system driven by mast cell mediators.

  3. System Convergence in Transport Modelling

    DEFF Research Database (Denmark)

    Rich, Jeppe; Nielsen, Otto Anker; Cantarella, Guilio E.

    2010-01-01

    A fundamental premise of most applied transport models is the existence and uniqueness of an equilibrium solution that balances demand x(t) and supply t(x). The demand consists of the people that travel in the transport system and on the defined network, whereas the supply consists of the resulting...... level-of-service attributes (e.g., travel time and cost) offered to travellers. An important source of complexity is the congestion, which causes increasing demand to affect travel time in a non-linear way. Transport models most often involve separate models for traffic assignment and demand modelling...... iterating between a route-choice (demand) model and a time-flow (supply) model. It is generally recognised that a simple iteration scheme where the level-of-service level is fed directly to the route-choice and vice versa may exhibit an unstable pattern and lead to cyclic unstable solutions. It can be shown...

  4. Fuel quality issues in stationary fuel cell systems.

    Energy Technology Data Exchange (ETDEWEB)

    Papadias, D.; Ahmed, S.; Kumar, R. (Chemical Sciences and Engineering Division)

    2012-02-07

    Fuel cell systems are being deployed in stationary applications for the generation of electricity, heat, and hydrogen. These systems use a variety of fuel cell types, ranging from the low temperature polymer electrolyte fuel cell (PEFC) to the high temperature solid oxide fuel cell (SOFC). Depending on the application and location, these systems are being designed to operate on reformate or syngas produced from various fuels that include natural gas, biogas, coal gas, etc. All of these fuels contain species that can potentially damage the fuel cell anode or other unit operations and processes that precede the fuel cell stack. These detrimental effects include loss in performance or durability, and attenuating these effects requires additional components to reduce the impurity concentrations to tolerable levels, if not eliminate the impurity entirely. These impurity management components increase the complexity of the fuel cell system, and they add to the system's capital and operating costs (such as regeneration, replacement and disposal of spent material and maintenance). This project reviewed the public domain information available on the impurities encountered in stationary fuel cell systems, and the effects of the impurities on the fuel cells. A database has been set up that classifies the impurities, especially in renewable fuels, such as landfill gas and anaerobic digester gas. It documents the known deleterious effects on fuel cells, and the maximum allowable concentrations of select impurities suggested by manufacturers and researchers. The literature review helped to identify the impurity removal strategies that are available, and their effectiveness, capacity, and cost. A generic model of a stationary fuel-cell based power plant operating on digester and landfill gas has been developed; it includes a gas processing unit, followed by a fuel cell system. The model includes the key impurity removal steps to enable predictions of impurity breakthrough

  5. A minimal physical model for crawling cells

    Science.gov (United States)

    Tiribocchi, Adriano; Tjhung, Elsen; Marenduzzo, Davide; Cates, Michael E.

    Cell motility in higher organisms (eukaryotes) is fundamental to biological functions such as wound healing or immune response, and is also implicated in diseases such as cancer. For cells crawling on solid surfaces, considerable insights into motility have been gained from experiments replicating such motion in vitro. Such experiments show that crawling uses a combination of actin treadmilling (polymerization), which pushes the front of a cell forward, and myosin-induced stress (contractility), which retracts the rear. We present a simplified physical model of a crawling cell, consisting of a droplet of active polar fluid with contractility throughout, but treadmilling connected to a thin layer near the supporting wall. The model shows a variety of shapes and/or motility regimes, some closely resembling cases seen experimentally. Our work supports the view that cellular motility exploits autonomous physical mechanisms whose operation does not need continuous regulatory effort.

  6. Model Reduction of Hybrid Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza

    gramians. Generalized gramians are the solutions to the observability and controllability Lyapunov inequalities. In the first framework the projection matrices are found based on the common generalized gramians. This framework preserves the stability of the original switched system for all switching...... is guaranteed to be preserved for arbitrary switching signal. To compute the common generalized gramians linear matrix inequalities (LMI’s) need to be solved. These LMI’s are not always feasible. In order to solve the problem of conservatism, the second framework is presented. In this method the projection......High-Technological solutions of today are characterized by complex dynamical models. A lot of these models have inherent hybrid/switching structure. Hybrid/switched systems are powerful models for distributed embedded systems design where discrete controls are applied to continuous processes...

  7. Numerical Modeling of Microelectrochemical Systems

    DEFF Research Database (Denmark)

    Adesokan, Bolaji James

    incorporates the finite size of ionic species in the transport equation. The model presents a more appropriate boundary conditions which describe the modified Butler-Volmer reaction kinetics and account for the surface capacitance of the thin electric double layer. We also have found analytical solution...... at the electrode in a microelectrochemical system. In our analysis, we account for the finite size properties of ions in the mass and the charge transport of ionic species in an electrochemical system. This term characterizes the saturation of the ionic species close to the electrode surface. We then analyse......The PhD dissertation is concerned with mathematical modeling and simulation of electrochemical systems. The first three chapters of the thesis consist of the introductory part, the model development chapter and the chapter on the summary of the main results. The remaining three chapters report...

  8. Modeling cell-in-cell structure into its biological significance

    OpenAIRE

    He, M-f; Wang, S; Wang, Y; Wang, X-n

    2013-01-01

    Although cell-in-cell structure was noted 100 years ago, the molecular mechanisms of ?entering' and the destination of cell-in-cell remain largely unclear. It takes place among the same type of cells (homotypic cell-in-cell) or different types of cells (heterotypic cell-in-cell). Cell-in-cell formation affects both effector cells and their host cells in multiple aspects, while cell-in-cell death is under more intensive investigation. Given that cell-in-cell has an important role in maintainin...

  9. Artificial cell mimics as simplified models for the study of cell biology.

    Science.gov (United States)

    Salehi-Reyhani, Ali; Ces, Oscar; Elani, Yuval

    2017-07-01

    Living cells are hugely complex chemical systems composed of a milieu of distinct chemical species (including DNA, proteins, lipids, and metabolites) interconnected with one another through a vast web of interactions: this complexity renders the study of cell biology in a quantitative and systematic manner a difficult task. There has been an increasing drive towards the utilization of artificial cells as cell mimics to alleviate this, a development that has been aided by recent advances in artificial cell construction. Cell mimics are simplified cell-like structures, composed from the bottom-up with precisely defined and tunable compositions. They allow specific facets of cell biology to be studied in isolation, in a simplified environment where control of variables can be achieved without interference from a living and responsive cell. This mini-review outlines the core principles of this approach and surveys recent key investigations that use cell mimics to address a wide range of biological questions. It will also place the field in the context of emerging trends, discuss the associated limitations, and outline future directions of the field. Impact statement Recent years have seen an increasing drive to construct cell mimics and use them as simplified experimental models to replicate and understand biological phenomena in a well-defined and controlled system. By summarizing the advances in this burgeoning field, and using case studies as a basis for discussion on the limitations and future directions of this approach, it is hoped that this minireview will spur others in the experimental biology community to use artificial cells as simplified models with which to probe biological systems.

  10. Tensegrity I. Cell structure and hierarchical systems biology

    Science.gov (United States)

    Ingber, Donald E.

    2003-01-01

    In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

  11. Control of Cell Fate in the Circulatory and Ventilatory Systems

    CERN Document Server

    Thiriet, Marc

    2012-01-01

    The volumes in this authoritative series present a multidisciplinary approach to modeling and simulation of flows in the cardiovascular and ventilatory systems, especially multiscale modeling and coupled simulations. The cardiovascular and respiratory systems are tightly coupled, as their primary function is to supply oxygen to and remove carbon dioxide from the body's cells. Because physiological conduits have deformable and reactive walls, macroscopic flow behavior and prediction must be coupled to nano- and microscopic events in a corrector scheme of regulated mechanisms. Therefore, investigation of flows of blood and air in physiological conduits requires an understanding of the biology, chemistry, and physics of these systems together with the mathematical tools to describe their functioning. Volumes 1 and 2 are devoted to cell organization and fate, as well as activities that are autoregulated and/or controlled by the cell environment. Volume 1 examined cellular features that allow adaptation to env...

  12. Executive Information Systems' Multidimensional Models

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available Executive Information Systems are design to improve the quality of strategic level of management in organization through a new type of technology and several techniques for extracting, transforming, processing, integrating and presenting data in such a way that the organizational knowledge filters can easily associate with this data and turn it into information for the organization. These technologies are known as Business Intelligence Tools. But in order to build analytic reports for Executive Information Systems (EIS in an organization we need to design a multidimensional model based on the business model from the organization. This paper presents some multidimensional models that can be used in EIS development and propose a new model that is suitable for strategic business requests.

  13. Turboelectric Distributed Propulsion System Modelling

    OpenAIRE

    Liu, Chengyuan

    2013-01-01

    The Blended-Wing-Body is a conceptual aircraft design with rear-mounted, over wing engines. Turboelectric distributed propulsion system with boundary layer ingestion has been considered for this aircraft. It uses electricity to transmit power from the core turbine to the fans, therefore dramatically increases bypass ratio to reduce fuel consumption and noise. This dissertation presents methods on designing the TeDP system, evaluating effects of boundary layer ingestion, modelling engine perfo...

  14. Cell of Origin and Cancer Stem Cells in Tumor Suppressor Mouse Models of Glioblastoma.

    Science.gov (United States)

    Alcantara Llaguno, Sheila R; Xie, Xuanhua; Parada, Luis F

    2016-01-01

    The cellular origins and the mechanisms of progression, maintenance of tumorigenicity, and therapeutic resistance are central questions in the glioblastoma multiforme (GBM) field. Using tumor suppressor mouse models, our group recently reported two independent populations of adult GBM-initiating central nervous system progenitors. We found different functional and molecular subtypes depending on the tumor-initiating cell lineage, indicating that the cell of origin is a driver of GBM subtype diversity. Using an in vivo model, we also showed that GBM cancer stem cells (CSCs) or glioma stem cells (GSCs) contribute to resistance to chemotherapeutic agents and that genetic ablation of GSCs leads to a delay in tumor progression. These studies are consistent with the cell of origin and CSCs as critical regulators of the pathogenesis of GBM. © 2016 Alcantara Llaguno et al; Published by Cold Spring Harbor Laboratory Press.

  15. A solid oxide fuel cell system for buildings

    International Nuclear Information System (INIS)

    Zink, Florian; Lu, Yixin; Schaefer, Laura

    2007-01-01

    This paper examines an integrated solid oxide fuel cell (SOFC) absorption heating and cooling system used for buildings. The integrated system can provide heating/cooling and/or hot water for buildings while consuming natural gas. The aim of this study is to give an overall description of the system. The possibility of such an integrated system is discussed and the configuration of the system is described. A system model is presented, and a specific case study of the system, which consists of a pre-commercial SOFC system and a commercial LiBr absorption system, is performed. In the case study, the detailed configuration of an integrated system is given, and the heat and mass balance and system performance are obtained through numerical calculation. Based on the case study, some considerations with respect to system component selection, system configuration and design are discussed. Additionally, the economic and environmental issues of this specific system are evaluated briefly. The results show that the combined system demonstrates great advantages in both technical and environmental aspects. With the present development trends in solid oxide fuel cells and the commercial status of absorption heating and cooling systems, it is very likely that such a combined system will become increasingly feasible within the following decade

  16. The Alpha Stem Cell Clinic: a model for evaluating and delivering stem cell-based therapies.

    Science.gov (United States)

    Trounson, Alan; DeWitt, Natalie D; Feigal, Ellen G

    2012-01-01

    Cellular therapies require the careful preparation, expansion, characterization, and delivery of cells in a clinical environment. There are major challenges associated with the delivery of cell therapies and high costs that will limit the companies available to fully evaluate their merit in clinical trials, and will handicap their application at the present financial environment. Cells will be manufactured in good manufacturing practice or near-equivalent facilities with prerequisite safety practices in place, and cell delivery systems will be specialized and require well-trained medical and nursing staff, technicians or nurses trained to handle cells once delivered, patient counselors, as well as statisticians and database managers who will oversee the monitoring of patients in relatively long-term follow-up studies. The model proposed for Alpha Stem Cell Clinics will initially use the capacities and infrastructure that exist in the most advanced tertiary medical clinics for delivery of established bone marrow stem cell therapies. As the research evolves, they will incorporate improved procedures and cell preparations. This model enables commercialization of medical devices, reagents, and other products required for cell therapies. A carefully constructed cell therapy clinical infrastructure with the requisite scientific, technical, and medical expertise and operational efficiencies will have the capabilities to address three fundamental and critical functions: 1) fostering clinical trials; 2) evaluating and establishing safe and effective therapies, and 3) developing and maintaining the delivery of therapies approved by the Food and Drug Administration, or other regulatory agencies.

  17. Modeling Neuropsychiatric and Neurodegenerative Diseases With Induced Pluripotent Stem Cells.

    Science.gov (United States)

    LaMarca, Elizabeth A; Powell, Samuel K; Akbarian, Schahram; Brennand, Kristen J

    2018-01-01

    Human-induced pluripotent stem cells (hiPSCs) have revolutionized our ability to model neuropsychiatric and neurodegenerative diseases, and recent progress in the field is paving the way for improved therapeutics. In this review, we discuss major advances in generating hiPSC-derived neural cells and cutting-edge techniques that are transforming hiPSC technology, such as three-dimensional "mini-brains" and clustered, regularly interspersed short palindromic repeats (CRISPR)-Cas systems. We examine specific examples of how hiPSC-derived neural cells are being used to uncover the pathophysiology of schizophrenia and Parkinson's disease, and consider the future of this groundbreaking research.

  18. Video distribution system cost model

    Science.gov (United States)

    Gershkoff, I.; Haspert, J. K.; Morgenstern, B.

    1980-01-01

    A cost model that can be used to systematically identify the costs of procuring and operating satellite linked communications systems is described. The user defines a network configuration by specifying the location of each participating site, the interconnection requirements, and the transmission paths available for the uplink (studio to satellite), downlink (satellite to audience), and voice talkback (between audience and studio) segments of the network. The model uses this information to calculate the least expensive signal distribution path for each participating site. Cost estimates are broken downy by capital, installation, lease, operations and maintenance. The design of the model permits flexibility in specifying network and cost structure.

  19. Dynamic Modeling of Cell-Free Biochemical Networks Using Effective Kinetic Models

    Directory of Open Access Journals (Sweden)

    Joseph A. Wayman

    2015-03-01

    Full Text Available Cell-free systems offer many advantages for the study, manipulation and modeling of metabolism compared to in vivo processes. Many of the challenges confronting genome-scale kinetic modeling can potentially be overcome in a cell-free system. For example, there is no complex transcriptional regulation to consider, transient metabolic measurements are easier to obtain, and we no longer have to consider cell growth. Thus, cell-free operation holds several significant advantages for model development, identification and validation. Theoretically, genome-scale cell-free kinetic models may be possible for industrially important organisms, such as E. coli, if a simple, tractable framework for integrating allosteric regulation with enzyme kinetics can be formulated. Toward this unmet need, we present an effective biochemical network modeling framework for building dynamic cell-free metabolic models. The key innovation of our approach is the integration of simple effective rules encoding complex allosteric regulation with traditional kinetic pathway modeling. We tested our approach by modeling the time evolution of several hypothetical cell-free metabolic networks. We found that simple effective rules, when integrated with traditional enzyme kinetic expressions, captured complex allosteric patterns such as ultrasensitivity or non-competitive inhibition in the absence of mechanistic information. Second, when integrated into network models, these rules captured classic regulatory patterns such as product-induced feedback inhibition. Lastly, we showed, at least for the network architectures considered here, that we could simultaneously estimate kinetic parameters and allosteric connectivity from synthetic data starting from an unbiased collection of possible allosteric structures using particle swarm optimization. However, when starting with an initial population that was heavily enriched with incorrect structures, our particle swarm approach could converge

  20. Fuel cell using a hydrogen generation system

    Science.gov (United States)

    Dentinger, Paul M.; Crowell, Jeffrey A. W.

    2010-10-19

    A system is described for storing and generating hydrogen and, in particular, a system for storing and generating hydrogen for use in an H.sub.2/O.sub.2 fuel cell. The hydrogen storage system uses beta particles from a beta particle emitting material to degrade an organic polymer material to release substantially pure hydrogen. In a preferred embodiment of the invention, beta particles from .sup.63Ni are used to release hydrogen from linear polyethylene.

  1. Information Systems Outsourcing Relationship Model

    Directory of Open Access Journals (Sweden)

    Richard Flemming

    2007-09-01

    Full Text Available Increasing attention is being paid to what determines the success of an information systems outsourcing arrangement. The current research aims to provide an improved understanding of the factors influencing the outcome of an information systems outsourcing relationship and to provide a preliminary validation of an extended outsourcing relationship model by interviews with information systems outsourcing professionals in both the client and vendor of a major Australian outsourcing relationship. It also investigates whether the client and the vendor perceive the relationship differently and if so, how they perceive it differently and whether the two perspectives are interrelated.

  2. Fuels processing for transportation fuel cell systems

    Science.gov (United States)

    Kumar, R.; Ahmed, S.

    Fuel cells primarily use hydrogen as the fuel. This hydrogen must be produced from other fuels such as natural gas or methanol. The fuel processor requirements are affected by the fuel to be converted, the type of fuel cell to be supplied, and the fuel cell application. The conventional fuel processing technology has been reexamined to determine how it must be adapted for use in demanding applications such as transportation. The two major fuel conversion processes are steam reforming and partial oxidation reforming. The former is established practice for stationary applications; the latter offers certain advantages for mobile systems and is presently in various stages of development. This paper discusses these fuel processing technologies and the more recent developments for fuel cell systems used in transportation. The need for new materials in fuels processing, particularly in the area of reforming catalysis and hydrogen purification, is discussed.

  3. PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems.

    Science.gov (United States)

    Ghaffarizadeh, Ahmadreza; Heiland, Randy; Friedman, Samuel H; Mumenthaler, Shannon M; Macklin, Paul

    2018-02-01

    Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal "virtual laboratory" for such multicellular systems simulates both the biochemical microenvironment (the "stage") and many mechanically and biochemically interacting cells (the "players" upon the stage). PhysiCell-physics-based multicellular simulator-is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility "out of the box." The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a "cellular cargo delivery" system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also represents a significant

  4. New Polymer Electrolyte Cell Systems

    Science.gov (United States)

    Smyrl, William H.; Owens, Boone B.; Mann, Kent; Pappenfus, T.; Henderson, W.

    2004-01-01

    PAPERS PUBLISHED: 1. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Complexes of Lithium Imide Salts with Tetraglyme and Their Polyelectrolyte Composite Materials. Journal of the Electrochemical Society (2004), 15 1 (2), A209-A2 15. 2. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Ionic-liquidlpolymer electrolyte composite materials for electrochemical device applications. Polymeric Materials Science and Engineering (2003), 88 302. 3. Pappenfus, Ted R.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; and Smyrl, William H. Ionic Conductivity of a poly(vinylpyridinium)/Silver Iodide Solid Polymer Electrolyte System. Solid State Ionics (in press 2004). 4. Pappenfus Ted M.; Mann, Kent R; Smyrl, William H. Polyelectrolyte Composite Materials with LiPFs and Tetraglyme. Electrochemical and Solid State Letters, (2004), 7(8), A254.

  5. An Equivalent Electrical Circuit Model of Proton Exchange Membrane Fuel Cells Based on Mathematical Modelling

    Directory of Open Access Journals (Sweden)

    Dinh An Nguyen

    2012-07-01

    Full Text Available Many of the Proton Exchange Membrane Fuel Cell (PEMFC models proposed in the literature consist of mathematical equations. However, they are not adequately practical for simulating power systems. The proposed model takes into account phenomena such as activation polarization, ohmic polarization, double layer capacitance and mass transport effects present in a PEM fuel cell. Using electrical analogies and a mathematical modeling of PEMFC, the circuit model is established. To evaluate the effectiveness of the circuit model, its static and dynamic performances under load step changes are simulated and compared to the numerical results obtained by solving the mathematical model. Finally, the applicability of our model is demonstrated by simulating a practical system.

  6. Stem cell models of polyglutamine diseases and their use in cell-based therapies

    Directory of Open Access Journals (Sweden)

    Evangelia eSiska

    2015-07-01

    Full Text Available Polyglutamine diseases are fatal neurological disorders that affect the central nervous system. They are caused by mutations in disease genes that contain CAG trinucleotide expansions in their coding regions. These mutations are translated into expanded glutamine chains in pathological proteins. Mutant proteins induce cytotoxicity, form intranuclear aggregates and cause neuronal cell death in specific brain regions. At the moment there is no cure for these diseases and only symptomatic treatments are available. Here, we discuss novel therapeutic approaches that aim in neuronal cell replacement using induced pluripotent or adult stem cells. Additionally, we present the beneficial effect of genetically engineered mesenchymal stem cells and their use as disease models or RNAi/gene delivery vehicles. In combination with their paracrine and cell-trophic properties, such cells may prove useful for the development of novel therapies against polyglutamine diseases.

  7. Aggregate modeling of manufacturing systems

    NARCIS (Netherlands)

    Lefeber, A.A.J.; Armbruster, H.D.; Kempf, K.G.; Keskinocak, P.; Uzsoy, R.

    2011-01-01

    In this chapter we will present three approaches to model manufacturing systems in an aggregate way leading to fast and effective (i.e., scalable) simulations that allow the development of simulation tools for rapid exploration of different production scenarios in a factory as well as in a whole

  8. Ventilation system in fire modelization

    International Nuclear Information System (INIS)

    Cordero Garcia, S.

    2012-01-01

    There is a model of fire in an enclosure formed by two rooms. In one of them, it will cause the fire and check how the system of ventilation in different configurations responds. In addition, the behavior of selected targets, which will be a configuration of cables similar to those found in nuclear power stations will be analyzed.

  9. An extensible analysable system model

    DEFF Research Database (Denmark)

    Probst, Christian W.; Hansen, Rene Rydhof

    2008-01-01

    , this does not hold for real physical systems. Approaches such as threat modelling try to target the formalisation of the real-world domain, but still are far from the rigid techniques available in security research. Many currently available approaches to assurance of critical infrastructure security...

  10. Aggregate modeling of manufacturing systems

    NARCIS (Netherlands)

    Lefeber, A.A.J.; Armbruster, H.D.

    2007-01-01

    In this report we will present three approaches to model manufacturing systems in an aggregate way leading to fast and effective (i.e., scalable) simulations that allow the development of simulation tools for rapid exploration of different production scenarios in a factory as well as in a whole

  11. Artificial Neural Network Based Model of Photovoltaic Cell

    Directory of Open Access Journals (Sweden)

    Messaouda Azzouzi

    2017-03-01

    Full Text Available This work concerns the modeling of a photovoltaic system and the prediction of the sensitivity of electrical parameters (current, power of the six types of photovoltaic cells based on voltage applied between terminals using one of the best known artificial intelligence technique which is the Artificial Neural Networks. The results of the modeling and prediction have been well shown as a function of number of iterations and using different learning algorithms to obtain the best results. 

  12. Modelling cell cycle synchronisation in networks of coupled radial glial cells.

    Science.gov (United States)

    Barrack, Duncan S; Thul, Rüdiger; Owen, Markus R

    2015-07-21

    Radial glial cells play a crucial role in the embryonic mammalian brain. Their proliferation is thought to be controlled, in part, by ATP mediated calcium signals. It has been hypothesised that these signals act to locally synchronise cell cycles, so that clusters of cells proliferate together, shedding daughter cells in uniform sheets. In this paper we investigate this cell cycle synchronisation by taking an ordinary differential equation model that couples the dynamics of intracellular calcium and the cell cycle and extend it to populations of cells coupled via extracellular ATP signals. Through bifurcation analysis we show that although ATP mediated calcium release can lead to cell cycle synchronisation, a number of other asynchronous oscillatory solutions including torus solutions dominate the parameter space and cell cycle synchronisation is far from guaranteed. Despite this, numerical results indicate that the transient and not the asymptotic behaviour of the system is important in accounting for cell cycle synchronisation. In particular, quiescent cells can be entrained on to the cell cycle via ATP mediated calcium signals initiated by a driving cell and crucially will cycle in near synchrony with the driving cell for the duration of neurogenesis. This behaviour is highly sensitive to the timing of ATP release, with release at the G1/S phase transition of the cell cycle far more likely to lead to near synchrony than release during mid G1 phase. This result, which suggests that ATP release timing is critical to radial glia cell cycle synchronisation, may help us to understand normal and pathological brain development. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Stochastic Modelling of Hydrologic Systems

    DEFF Research Database (Denmark)

    Jonsdottir, Harpa

    2007-01-01

    In this PhD project several stochastic modelling methods are studied and applied on various subjects in hydrology. The research was prepared at Informatics and Mathematical Modelling at the Technical University of Denmark. The thesis is divided into two parts. The first part contains...... an introduction and an overview of the papers published. Then an introduction to basic concepts in hydrology along with a description of hydrological data is given. Finally an introduction to stochastic modelling is given. The second part contains the research papers. In the research papers the stochastic methods...... are described, as at the time of publication these methods represent new contribution to hydrology. The second part also contains additional description of software used and a brief introduction to stiff systems. The system in one of the papers is stiff....

  14. Thermodynamic modeling of complex systems

    DEFF Research Database (Denmark)

    Liang, Xiaodong

    after an oil spill. Engineering thermodynamics could be applied in the state-of-the-art sonar products through advanced artificial technology, if the speed of sound, solubility and density of oil-seawater systems could be satisfactorily modelled. The addition of methanol or glycols into unprocessed well...... is successfully applied to model the phase behaviour of water, chemical and hydrocarbon (oil) containing systems with newly developed pure component parameters for water and chemicals and characterization procedures for petroleum fluids. The performance of the PCSAFT EOS on liquid-liquid equilibria of water...... with hydrocarbons has been under debate for some vii years. An interactive step-wise procedure is proposed to fit the model parameters for small associating fluids by taking the liquid-liquid equilibrium data into account. It is still far away from a simple task to apply PC-SAFT in routine PVT simulations and phase...

  15. Central infusion of leptin improves insulin resistance and suppresses beta-cell function, but not beta-cell mass, primarily through the sympathetic nervous system in a type 2 diabetic rat model.

    Science.gov (United States)

    Park, Sunmin; Ahn, Il Sung; Kim, Da Sol

    2010-06-05

    We investigated whether hypothalamic leptin alters beta-cell function and mass directly via the sympathetic nervous system (SNS) or indirectly as the result of altered insulin resistant states. The 90% pancreatectomized male Sprague Dawley rats had sympathectomy into the pancreas by applying phenol into the descending aorta (SNSX) or its sham operation (Sham). Each group was divided into two sections, receiving either leptin at 300ng/kgbw/h or artificial cerebrospinal fluid (aCSF) via intracerebroventricular (ICV) infusion for 3h as a short-term study. After finishing the infusion study, ICV leptin (3mug/kg bw/day) or ICV aCSF (control) was infused in rats fed 30 energy % fat diets by osmotic pump for 4weeks. At the end of the long-term study, glucose-stimulated insulin secretion and islet morphometry were analyzed. Acute ICV leptin administration in Sham rats, but not in SNSX rats, suppressed the first- and second-phase insulin secretion at hyperglycemic clamp by about 48% compared to the control. Regardless of SNSX, the 4-week administration of ICV leptin improved glucose tolerance during oral glucose tolerance tests and insulin sensitivity at hyperglycemic clamp, compared to the control, while it suppressed second-phase insulin secretion in Sham rats but not in SNSX rats. However, the pancreatic beta-cell area and mass were not affected by leptin and SNSX, though ICV leptin decreased individual beta-cell size and concomitantly increased beta-cell apoptosis in Sham rats. Leptin directly decreases insulin secretion capacity mainly through the activation of SNS without modulating pancreatic beta-cell mass.

  16. Teledyne Energy Systems, Inc., Proton Exchange Member (PEM) Fuel Cell Engineering Model Powerplant. Test Report: Initial Benchmark Tests in the Original Orientation

    Science.gov (United States)

    Loyselle, Patricia; Prokopius, Kevin

    2011-01-01

    Proton Exchange Membrane (PEM) fuel cell technology is the leading candidate to replace the alkaline fuel cell technology, currently used on the Shuttle, for future space missions. During a 5-yr development program, a PEM fuel cell powerplant was developed. This report details the initial performance evaluation test results of the powerplant.

  17. Systematic reconstruction of TRANSPATH data into cell system markup language.

    Science.gov (United States)

    Nagasaki, Masao; Saito, Ayumu; Li, Chen; Jeong, Euna; Miyano, Satoru

    2008-06-23

    Many biological repositories store information based on experimental study of the biological processes within a cell, such as protein-protein interactions, metabolic pathways, signal transduction pathways, or regulations of transcription factors and miRNA. Unfortunately, it is difficult to directly use such information when generating simulation-based models. Thus, modeling rules for encoding biological knowledge into system-dynamics-oriented standardized formats would be very useful for fully understanding cellular dynamics at the system level. We selected the TRANSPATH database, a manually curated high-quality pathway database, which provides a plentiful source of cellular events in humans, mice, and rats, collected from over 31,500 publications. In this work, we have developed 16 modeling rules based on hybrid functional Petri net with extension (HFPNe), which is suitable for graphical representing and simulating biological processes. In the modeling rules, each Petri net element is incorporated with Cell System Ontology to enable semantic interoperability of models. As a formal ontology for biological pathway modeling with dynamics, CSO also defines biological terminology and corresponding icons. By combining HFPNe with the CSO features, it is possible to make TRANSPATH data to simulation-based and semantically valid models. The results are encoded into a biological pathway format, Cell System Markup Language (CSML), which eases the exchange and integration of biological data and models. By using the 16 modeling rules, 97% of the reactions in TRANSPATH are converted into simulation-based models represented in CSML. This reconstruction demonstrates that it is possible to use our rules to generate quantitative models from static pathway descriptions.

  18. Cotangent Models for Integrable Systems

    Science.gov (United States)

    Kiesenhofer, Anna; Miranda, Eva

    2017-03-01

    We associate cotangent models to a neighbourhood of a Liouville torus in symplectic and Poisson manifolds focusing on b-Poisson/ b-symplectic manifolds. The semilocal equivalence with such models uses the corresponding action-angle theorems in these settings: the theorem of Liouville-Mineur-Arnold for symplectic manifolds and an action-angle theorem for regular Liouville tori in Poisson manifolds (Laurent- Gengoux et al., IntMath Res Notices IMRN 8: 1839-1869, 2011). Our models comprise regular Liouville tori of Poisson manifolds but also consider the Liouville tori on the singular locus of a b-Poisson manifold. For this latter class of Poisson structures we define a twisted cotangent model. The equivalence with this twisted cotangent model is given by an action-angle theorem recently proved by the authors and Scott (Math. Pures Appl. (9) 105(1):66-85, 2016). This viewpoint of cotangent models provides a new machinery to construct examples of integrable systems, which are especially valuable in the b-symplectic case where not many sources of examples are known. At the end of the paper we introduce non-degenerate singularities as lifted cotangent models on b-symplectic manifolds and discuss some generalizations of these models to general Poisson manifolds.

  19. A Two-Phenotype Model of Immune Evasion by Cancer Cells

    NARCIS (Netherlands)

    Bayer, Péter; Brown, Joel; Stankova, Katerina

    2017-01-01

    We propose a model with two types of cancer cells differentiated by their defense mechanisms against the immune system. ``Selfish'' cancer cells develop defense mechanisms that benefit the individual cell, whereas ``cooperative'' cells deploy countermeasures that increase the chance of survival of

  20. Noninvasive Assessment of Tumor Cell Proliferation in Animal Models

    Directory of Open Access Journals (Sweden)

    Matthias Edinger

    1999-10-01

    Full Text Available Revealing the mechanisms of neoplastic disease and enhancing our ability to intervene in these processes requires an increased understanding of cellular and molecular changes as they occur in intact living animal models. We have begun to address these needs by developing a method of labeling tumor cells through constitutive expression of an optical reporter gene, noninvasively monitoring cellular proliferation in vivo using a sensitive photon detection system. A stable line of HeLa cells that expressed a modified firefly luciferase gene was generated, proliferation of these cells in irradiated severe combined immunodeficiency (SCID mice was monitored. Tumor cells were introduced into animals via subcutaneous, intraperitoneal and intravenous inoculation and whole body images, that revealed tumor location and growth kinetics, were obtained. The number of photons that were emitted from the labeled tumor cells and transmitted through murine tissues was sufficient to detect 1×103 cells in the peritoneal cavity, 1×104 cells at subcutaneous sites and 1×106 circulating cells immediately following injection. The kinetics of cell proliferation, as measured by photon emission, was exponential in the peritoneal cavity and at subcutaneous sites. Intravenous inoculation resulted in detectable colonies of tumor cells in animals receiving more than 1×103 cells. Our demonstrated ability to detect small numbers of tumor cells in living animals noninvasively suggests that therapies designed to treat minimal disease states, as occur early in the disease course and after elimination of the tumor mass, may be monitored using this approach. Moreover, it may be possible to monitor micrometastases and evaluate the molecular steps in the metastatic process. Spatiotemporal analyses of neoplasia will improve the predictability of animal models of human disease as study groups can be followed over time, this method will accelerate development of novel therapeutic

  1. Thermal modelling of an AMTEC recirculating cell

    International Nuclear Information System (INIS)

    Suitor, J.W.; Williams, R.M.; Underwood, M.L.; Ryan, M.A.; Jeffries-Nakamura, B.; O'Connor, D.

    1992-01-01

    A modeling program was developed to determine the impact of various design parameters on the operation of an AMTEC system. Temperature profiles generated by the modeling program were compared to actual experimental data to verify the model accuracy. The model was then extended to predict the impact of device design on operational performance. The effect of heat loss form the liquid sodium supply end was studied for this paper

  2. PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems

    Science.gov (United States)

    Ghaffarizadeh, Ahmadreza; Mumenthaler, Shannon M.

    2018-01-01

    Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal “virtual laboratory” for such multicellular systems simulates both the biochemical microenvironment (the “stage”) and many mechanically and biochemically interacting cells (the “players” upon the stage). PhysiCell—physics-based multicellular simulator—is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility “out of the box.” The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a “cellular cargo delivery” system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also

  3. Using Human Induced Pluripotent Stem Cells to Model Skeletal Diseases.

    Science.gov (United States)

    Barruet, Emilie; Hsiao, Edward C

    2016-01-01

    Musculoskeletal disorders affecting the bones and joints are major health problems among children and adults. Major challenges such as the genetic origins or poor diagnostics of severe skeletal disease hinder our understanding of human skeletal diseases. The recent advent of human induced pluripotent stem cells (human iPS cells) provides an unparalleled opportunity to create human-specific models of human skeletal diseases. iPS cells have the ability to self-renew, allowing us to obtain large amounts of starting material, and have the potential to differentiate into any cell types in the body. In addition, they can carry one or more mutations responsible for the disease of interest or be genetically corrected to create isogenic controls. Our work has focused on modeling rare musculoskeletal disorders including fibrodysplasia ossificans progressive (FOP), a congenital disease of increased heterotopic ossification. In this review, we will discuss our experiences and protocols differentiating human iPS cells toward the osteogenic lineage and their application to model skeletal diseases. A number of critical challenges and exciting new approaches are also discussed, which will allow the skeletal biology field to harness the potential of human iPS cells as a critical model system for understanding diseases of abnormal skeletal formation and bone regeneration.

  4. Voronoi Cell Patterns: theoretical model and application to submonolayer growth

    Science.gov (United States)

    González, Diego Luis; Einstein, T. L.

    2012-02-01

    We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We apply our model to describe the Voronoi cell patterns of island nucleation for critical island sizes i=0,1,2,3. Experimental results for the Voronoi cells of InAs/GaAs quantum dots are also described by our model.

  5. Stochastic modeling of oligodendrocyte generation in cell culture: model validation with time-lapse data

    Directory of Open Access Journals (Sweden)

    Noble Mark

    2006-05-01

    Full Text Available Abstract Background The purpose of this paper is two-fold. The first objective is to validate the assumptions behind a stochastic model developed earlier by these authors to describe oligodendrocyte generation in cell culture. The second is to generate time-lapse data that may help biomathematicians to build stochastic models of cell proliferation and differentiation under other experimental scenarios. Results Using time-lapse video recording it is possible to follow the individual evolutions of different cells within each clone. This experimental technique is very laborious and cannot replace model-based quantitative inference from clonal data. However, it is unrivalled in validating the structure of a stochastic model intended to describe cell proliferation and differentiation at the clonal level. In this paper, such data are reported and analyzed for oligodendrocyte precursor cells cultured in vitro. Conclusion The results strongly support the validity of the most basic assumptions underpinning the previously proposed model of oligodendrocyte development in cell culture. However, there are some discrepancies; the most important is that the contribution of progenitor cell death to cell kinetics in this experimental system has been underestimated.

  6. Modelling real solar cell using PSCAD/MATLAB

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Sergio; Silva, Marco; Fernandes, Filipe; Vale, Zita [Polytechnic of Porto (Portugal). GECAD - Knowledge Engineering and Decision Support Research Center

    2012-07-01

    This paper presents the development of a solar photovoltaic (PV) model based on PSCAD/EMTDC - Power System Computer Aided Design - including a mathematical model study. An additional algorithm has been implemented in MATLAB software in order to calculate several parameters required by the PSCAD developed model. All the simulation study has been performed in PSCAD/MATLAB software simulation tool. A real data base concerning irradiance, cell temperature and PV power generation was used in order to support the evaluation of the implemented PV model. (orig.)

  7. Modeling human infertility with pluripotent stem cells

    Directory of Open Access Journals (Sweden)

    Di Chen

    2017-05-01

    Full Text Available Human fertility is dependent upon the correct establishment and differentiation of the germline. This is because no other cell type in the body is capable of passing a genome and epigenome from parent to child. Terminally differentiated germline cells in the adult testis and ovary are called gametes. However, the initial specification of germline cells occurs in the embryo around the time of gastrulation. Most of our knowledge regarding the cell and molecular events that govern human germline specification involves extrapolating scientific principles from model organisms, most notably the mouse. However, recent work using next generation sequencing, gene editing and differentiation of germline cells from pluripotent stem cells has revealed that the core molecular mechanisms that regulate human germline development are different from rodents. Here, we will discuss the major molecular pathways required for human germline differentiation and how pluripotent stem cells have revolutionized our ability to study the earliest steps in human embryonic lineage specification in order to understand human fertility.

  8. High throughput solar cell ablation system

    Science.gov (United States)

    Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John

    2012-09-11

    A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.

  9. Cooling Grapple System for FMEF hot cell

    International Nuclear Information System (INIS)

    Semmens, L.S.; Frandsen, G.B.; Tome, R.

    1983-01-01

    A Cooling Grapple System was designed and built to handle fuel assemblies within the FMEF hot cell. The variety of functions for which it is designed makes it unique from grapples presently in use. The Cooling Grapple can positively grip and transport assemblies vertically, retrieve assemblies from molten sodium where six inches of grapple tip is submerged, cool 7 kw assemblies in argon, and service an in-cell area of 372 m 2 (4000 ft 2 ). Novel and improved operating and maintenance features were incorporated in the design including a shear pin and mechanical catcher system to prevent overloading the grapple while allowing additional reaction time for crane shutdown

  10. Graph modeling systems and methods

    Science.gov (United States)

    Neergaard, Mike

    2015-10-13

    An apparatus and a method for vulnerability and reliability modeling are provided. The method generally includes constructing a graph model of a physical network using a computer, the graph model including a plurality of terminating vertices to represent nodes in the physical network, a plurality of edges to represent transmission paths in the physical network, and a non-terminating vertex to represent a non-nodal vulnerability along a transmission path in the physical network. The method additionally includes evaluating the vulnerability and reliability of the physical network using the constructed graph model, wherein the vulnerability and reliability evaluation includes a determination of whether each terminating and non-terminating vertex represents a critical point of failure. The method can be utilized to evaluate wide variety of networks, including power grid infrastructures, communication network topologies, and fluid distribution systems.

  11. Human pluripotent stem cells: an emerging model in developmental biology.

    Science.gov (United States)

    Zhu, Zengrong; Huangfu, Danwei

    2013-02-01

    Developmental biology has long benefited from studies of classic model organisms. Recently, human pluripotent stem cells (hPSCs), including human embryonic stem cells and human induced pluripotent stem cells, have emerged as a new model system that offers unique advantages for developmental studies. Here, we discuss how studies of hPSCs can complement classic approaches using model organisms, and how hPSCs can be used to recapitulate aspects of human embryonic development 'in a dish'. We also summarize some of the recently developed genetic tools that greatly facilitate the interrogation of gene function during hPSC differentiation. With the development of high-throughput screening technologies, hPSCs have the potential to revolutionize gene discovery in mammalian development.

  12. Mathematical Models and Methods for Living Systems

    CERN Document Server

    Chaplain, Mark; Pugliese, Andrea

    2016-01-01

    The aim of these lecture notes is to give an introduction to several mathematical models and methods that can be used to describe the behaviour of living systems. This emerging field of application intrinsically requires the handling of phenomena occurring at different spatial scales and hence the use of multiscale methods. Modelling and simulating the mechanisms that cells use to move, self-organise and develop in tissues is not only fundamental to an understanding of embryonic development, but is also relevant in tissue engineering and in other environmental and industrial processes involving the growth and homeostasis of biological systems. Growth and organization processes are also important in many tissue degeneration and regeneration processes, such as tumour growth, tissue vascularization, heart and muscle functionality, and cardio-vascular diseases.

  13. Numerical simulation model of multijunction solar cell

    NARCIS (Netherlands)

    Babar, M.; Al-Ammar, E.A.; Malik, N.H.

    2012-01-01

    Multi-junction solar cells play an important and significant role in the Concentrated Photovoltaic (CPV) Systems. Recent developments in Concentrated Photovoltaic concerning high power production and cost effective- ness along with better efficiency are due to the advancements in multi-junction

  14. Dynamical analysis of uterine cell electrical activity model.

    Science.gov (United States)

    Rihana, S; Santos, J; Mondie, S; Marque, C

    2006-01-01

    The uterus is a physiological system consisting of a large number of interacting smooth muscle cells. The uterine excitability changes remarkably with time, generally quiescent during pregnancy, the uterus exhibits forceful synchronized contractions at term leading to fetus expulsion. These changes characterize thus a dynamical system susceptible of being studied through formal mathematical tools. Multiple physiological factors are involved in the regulation process of this complex system. Our aim is to relate the physiological factors to the uterine cell dynamic behaviors. Taking into account a previous work presented, in which the electrical activity of a uterine cell is described by a set of ordinary differential equations, we analyze the impact of physiological parameters on the response of the model, and identify the main subsystems generating the complex uterine electrical activity, with respect to physiological data.

  15. Portable 25W hybrid fuel cell system

    International Nuclear Information System (INIS)

    Green, K.; Slee, R.; Tilley, J.

    2003-01-01

    Increased operating periods for portable electrical equipment are driving the development of battery and fuel cell technologies. Fuel cell systems promise greater endurance than battery based systems, and this paper describes the research into, and design of, a hybrid lithium-ion battery / fuel cell power source. The device is primarily aimed at military applications such as powering army radio sets and the UK MoD's Integrated Soldier Technology (IST) programme, but would be equally suitable as a power source for civilian applications such as camcorders, battery chargers etc. The air-breathing fuel cell comprises low cost, robust components, and a single cell is capable of developing >0.5W cm -2 . This power rating, however, is reduced in a stack where heat rejection becomes a critical issue. The stack design lends itself to facile manufacture, and the stack can be assembled in minutes by simply stacking the components into place. The remainder of the system includes two lithium-ion battery packs which provide start-up and shutdown power, and enable a silent-operating mode, during which the fuel cell is powered down, to be selected. The intelligent, electronic control, based upon an embedded RISC microprocessor, ensures safe operation and the recharge of the batteries. The overall system is capable of delivering 25W continuous power at an operating voltage of 12V dc. Preliminary testing results are reported. Advantages of this system include a relatively high gravimetric power density, load-following operation and the confidence of a high performance battery as an emergency backup. (author)

  16. Dynamic characteristics of an automotive fuel cell system for transitory load changes

    DEFF Research Database (Denmark)

    Rabbani, Raja Abid; Rokni, Masoud

    2013-01-01

    A dynamic model of Polymer Electrolyte Membrane Fuel Cell (PEMFC) system is developed to investigate the behavior and transient response of a fuel cell system for automotive applications. Fuel cell dynamics are subjected to reactant flows, heat management and water transportation inside the fuel...

  17. A comparative study of approaches to direct methanol fuel cells modelling

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [Instituto Nacional de Engenharia, Tecnologia e Inovacao, Paco do Lumiar, 22,1649-038 (Portugal)

    2007-03-15

    Fuel cell modelling has received much attention over the past decade in an attempt to better understand the phenomena occurring within the cell. Mathematical models and simulation are needed as tools for design optimization of fuel cells, stacks and fuel cell power systems. Analytical, semi-empirical and mechanistic models for direct methanol fuel cells (DMFC) are reviewed. Effective models were until now developed describing the fundamental electrochemical and transport phenomena taking place in the cell. More research is required to develop models that can account for the two-phase flows occurring in the anode and cathode of the DMFC. The merits and demerits of the models are presented. Selected models of different categories are implemented and discussed. Finally, one of the selected simplified models is proposed as a computer-aided tool for real-time system level DMFC calculations. (author)

  18. Discrete modelling of drapery systems

    Science.gov (United States)

    Thoeni, Klaus; Giacomini, Anna

    2016-04-01

    Drapery systems are an efficient and cost-effective measure in preventing and controlling rockfall hazards on rock slopes. The simplest form consists of a row of ground anchors along the top of the slope connected to a horizontal support cable from which a wire mesh is suspended down the face of the slope. Such systems are generally referred to as simple or unsecured draperies (Badger and Duffy 2012). Variations such as secured draperies, where a pattern of ground anchors is incorporated within the field of the mesh, and hybrid systems, where the upper part of an unsecured drapery is elevated to intercept rockfalls originating upslope of the installation, are becoming more and more popular. This work presents a discrete element framework for simulation of unsecured drapery systems and its variations. The numerical model is based on the classical discrete element method (DEM) and implemented into the open-source framework YADE (Šmilauer et al., 2010). The model takes all relevant interactions between block, drapery and slope into account (Thoeni et al., 2014) and was calibrated and validated based on full-scale experiments (Giacomini et al., 2012).The block is modelled as a rigid clump made of spherical particles which allows any shape to be approximated. The drapery is represented by a set of spherical particle with remote interactions. The behaviour of the remote interactions is governed by the constitutive behaviour of the wire and generally corresponds to a piecewise linear stress-strain relation (Thoeni et al., 2013). The same concept is used to model wire ropes. The rock slope is represented by rigid triangular elements where material properties (e.g., normal coefficient of restitution, friction angle) are assigned to each triangle. The capabilities of the developed model to simulate drapery systems and estimate the residual hazard involved with such systems is shown. References Badger, T.C., Duffy, J.D. (2012) Drapery systems. In: Turner, A.K., Schuster R

  19. Quantum models of classical systems

    International Nuclear Information System (INIS)

    Hájíček, P

    2015-01-01

    Quantum statistical methods that are commonly used for the derivation of classical thermodynamic properties are extended to classical mechanical properties. The usual assumption that every real motion of a classical mechanical system is represented by a sharp trajectory is not testable and is replaced by a class of fuzzy models, the so-called maximum entropy (ME) packets. The fuzzier are the compared classical and quantum ME packets, the better seems to be the match between their dynamical trajectories. Classical and quantum models of a stiff rod will be constructed to illustrate the resulting unified quantum theory of thermodynamic and mechanical properties. (paper)

  20. Temperature dependent estimator for load cells using an adaptive neuro-fuzzy inference system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K-C [Department of Automation Engineering, National Formosa University, Huwei, Yunlin 63208, Taiwan (China)

    2005-01-01

    Accurate weighting of pieces in various temperature environments for load cells is a key feature in many industrial applications. This paper proposes a method to achieve high-precision {+-}0.56/3000 grams for a load-cell-based weighting system by using ANFIS. ANFIS is used to model the relationship between the reading of load cells and the actual weight of samples considering temperature-varying effect and nonlinearity of the load cells. The model of the load-cell-based weighting system can accurately estimate the weight of test samples from the load cell reading. The proposed ANFIS-based method is convenient for use and can improve the precision of digital load cell measurement systems. Experiments demonstrate the validity and effectiveness of fuzzy neural networks for modeling of load cells and the results show that the proposed ANFIS-based method outperforms some existing methods in terms of modeling and prediction accuracy.

  1. Temperature dependent estimator for load cells using an adaptive neuro-fuzzy inference system

    International Nuclear Information System (INIS)

    Lee, K-C

    2005-01-01

    Accurate weighting of pieces in various temperature environments for load cells is a key feature in many industrial applications. This paper proposes a method to achieve high-precision ±0.56/3000 grams for a load-cell-based weighting system by using ANFIS. ANFIS is used to model the relationship between the reading of load cells and the actual weight of samples considering temperature-varying effect and nonlinearity of the load cells. The model of the load-cell-based weighting system can accurately estimate the weight of test samples from the load cell reading. The proposed ANFIS-based method is convenient for use and can improve the precision of digital load cell measurement systems. Experiments demonstrate the validity and effectiveness of fuzzy neural networks for modeling of load cells and the results show that the proposed ANFIS-based method outperforms some existing methods in terms of modeling and prediction accuracy

  2. Modeling Ebola Virus Genome Replication and Transcription with Minigenome Systems.

    Science.gov (United States)

    Cressey, Tessa; Brauburger, Kristina; Mühlberger, Elke

    2017-01-01

    In this chapter, we describe the minigenome system for Ebola virus (EBOV), which reconstitutes EBOV polymerase activity in cells and can be used to model viral genome replication and transcription. This protocol comprises all steps including cell culture, plasmid preparation, transfection, and luciferase reporter assay readout.

  3. Computer modeling describes gravity-related adaptation in cell cultures.

    Science.gov (United States)

    Alexandrov, Ludmil B; Alexandrova, Stoyana; Usheva, Anny

    2009-12-16

    Questions about the changes of biological systems in response to hostile environmental factors are important but not easy to answer. Often, the traditional description with differential equations is difficult due to the overwhelming complexity of the living systems. Another way to describe complex systems is by simulating them with phenomenological models such as the well-known evolutionary agent-based model (EABM). Here we developed an EABM to simulate cell colonies as a multi-agent system that adapts to hyper-gravity in starvation conditions. In the model, the cell's heritable characteristics are generated and transferred randomly to offspring cells. After a qualitative validation of the model at normal gravity, we simulate cellular growth in hyper-gravity conditions. The obtained data are consistent with previously confirmed theoretical and experimental findings for bacterial behavior in environmental changes, including the experimental data from the microgravity Atlantis and the Hypergravity 3000 experiments. Our results demonstrate that it is possible to utilize an EABM with realistic qualitative description to examine the effects of hypergravity and starvation on complex cellular entities.

  4. Onion root tip cell system for biodosimetry?

    International Nuclear Information System (INIS)

    Paradiz, J; Druskovic, B.; Lovka, M.; Skrk, J.

    1996-01-01

    Methodology for radiation dose assessment based on chromosomal damage to plant cells has no yet been established, although root meristems have been the pioneer cytogenetic materials and profound analyses of irradiated meristematic cells of horse bean (Viciafaba L.) had been performed. Onion (Allium cepa L.) root tips frequently used for radiation cytogenetic studies, are recently considered to be one of the most promising plant test system for the detection of genotoxic environmental pollutants. We studied the possibility of using cytogenetic analyses of irradiated onion cells to determine the effective biological dose of ionizing radiation. The dose-effect relationships for chromosomal damages to onion meristematic cells were established after plants had been irradiated and subsequently grown in both laboratory and field conditions

  5. Bioengineered Liver Models for Drug Testing and Cell Differentiation Studies

    Directory of Open Access Journals (Sweden)

    Gregory H. Underhill

    2018-01-01

    Full Text Available In vitro models of the human liver are important for the following: (1 mitigating the risk of drug-induced liver injury to human beings, (2 modeling human liver diseases, (3 elucidating the role of single and combinatorial microenvironmental cues on liver cell function, and (4 enabling cell-based therapies in the clinic. Methods to isolate and culture primary human hepatocytes (PHHs, the gold standard for building human liver models, were developed several decades ago; however, PHHs show a precipitous decline in phenotypic functions in 2-dimensional extracellular matrix–coated conventional culture formats, which does not allow chronic treatment with drugs and other stimuli. The development of several engineering tools, such as cellular microarrays, protein micropatterning, microfluidics, biomaterial scaffolds, and bioprinting, now allow precise control over the cellular microenvironment for enhancing the function of both PHHs and induced pluripotent stem cell–derived human hepatocyte-like cells; long-term (4+ weeks stabilization of hepatocellular function typically requires co-cultivation with liver-derived or non–liver-derived nonparenchymal cell types. In addition, the recent development of liver organoid culture systems can provide a strategy for the enhanced expansion of therapeutically relevant cell types. Here, we discuss advances in engineering approaches for constructing in vitro human liver models that have utility in drug screening and for determining microenvironmental determinants of liver cell differentiation/function. Design features and validation data of representative models are presented to highlight major trends followed by the discussion of pending issues that need to be addressed. Overall, bioengineered liver models have significantly advanced our understanding of liver function and injury, which will prove useful for drug development and ultimately cell-based therapies.

  6. Models of the venous system

    DEFF Research Database (Denmark)

    Mehlsen, J

    2000-01-01

    Cardiac output is largely controlled by venous return, the driving force of which is the energy remaining at the postcapillary venous site. This force is influenced by forces acting close to the right atrium, and internally or externally upon the veins along their course. Analogue models of the v......Cardiac output is largely controlled by venous return, the driving force of which is the energy remaining at the postcapillary venous site. This force is influenced by forces acting close to the right atrium, and internally or externally upon the veins along their course. Analogue models...... of the venous system require at least three elements: a resistor, a capacitor and an inductor, with the latter being of more importance in the venous than in the arterial system. Non-linearities must be considered in pressure/flow relations in the small venules, during venous collapse, or low flow conditions...

  7. Studies of Catalytic Model Systems

    DEFF Research Database (Denmark)

    Holse, Christian

    The overall topic of this thesis is within the field of catalysis, were model systems of different complexity have been studied utilizing a multipurpose Ultra High Vacuum chamber (UHV). The thesis falls in two different parts. First a simple model system in the form of a ruthenium single crystal...... of the Cu/ZnO nanoparticles is highly relevant to industrial methanol synthesis for which the direct interaction of Cu and ZnO nanocrystals synergistically boost the catalytic activity. The dynamical behavior of the nanoparticles under reducing and oxidizing environments were studied by means of ex situ X......-ray Photoelectron Electron Spectroscopy (XPS) and in situ Transmission Electron Microscopy (TEM). The surface composition of the nanoparticles changes reversibly as the nanoparticles exposed to cycles of high-pressure oxidation and reduction (200 mbar). Furthermore, the presence of metallic Zn is observed by XPS...

  8. A human stem cell-based model for identifying adverse effects of organic and inorganic chemicals on the developing nervous system

    DEFF Research Database (Denmark)

    Buzanska, Leonora; Sypecka, Joanna; Nerini-Molteni, Silvia

    2009-01-01

    (sodium tellurite, methylmercury chloride, cadmium chloride, chlorpyrifos, and L-glutamate) and non-neurotoxic (acetaminophen, theophylline, and D-glutamate) compounds. In addition, we investigated the effect of some compounds on key neurodevelopmental processes like cell proliferation, apoptotic cell...... >> chlorpyrifos >> L-glutamate. Fifty nanomolar methylmercury chloride (MeHgCl) inhibited proliferation and induced apoptosis in early-stage cells. At the differentiated stage, 1 muM MeHgCl induced selective loss of S100 beta-expressing astrocytic cells. One millimolar L-glutamate did not influence the early...

  9. Basic model and governing equation of solar cells used in power and control applications

    NARCIS (Netherlands)

    Izadian, A.; Pourtaherian, A.; Motahari, S.

    2012-01-01

    This paper provides an overview of modeling of a group of commercially available solar cells to ease the study of solar powered electric systems. The models solar cells can be accurately used to predict the behavior of the system operation under different conditions.

  10. Repair-misrepair model of cell survival

    International Nuclear Information System (INIS)

    Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.

    1980-01-01

    During the last three years a new model, the repair-misrepair model (RMR) has been proposed, to interpret radiobiological experiments with heavy ions. In using the RMR model it became apparent that some of its features are suitable for handling the effects produced by a variety of environmental agents in addition to ionizing radiation. Two separate sequences of events are assumed to take place in an irradiated cell. The first sequence begins with an initial energy transfer consisting of ionizations and excitations, culminating via fast secondary physical and chemical processes in established macromolecular lesions in essential cell structures. The second sequence contains the responses of the cell to the lesions and consists of the processes of recognition and molecular repair. In normal cells there exists one repair process or at most a few enzymatic repair processes for each essential macromolecular lesion. The enzymatic repair processes may last for hours and minutes, and can be separated in time from the initial physicochemical and later genetic phases

  11. Aerial Measuring System Sensor Modeling

    International Nuclear Information System (INIS)

    Detwiler, R.S.

    2002-01-01

    This project deals with the modeling the Aerial Measuring System (AMS) fixed-wing and rotary-wing sensor systems, which are critical U.S. Department of Energy's National Nuclear Security Administration (NNSA) Consequence Management assets. The fixed-wing system is critical in detecting lost or stolen radiography or medical sources, or mixed fission products as from a commercial power plant release at high flying altitudes. The helicopter is typically used at lower altitudes to determine ground contamination, such as in measuring americium from a plutonium ground dispersal during a cleanup. Since the sensitivity of these instruments as a function of altitude is crucial in estimating detection limits of various ground contaminations and necessary count times, a characterization of their sensitivity as a function of altitude and energy is needed. Experimental data at altitude as well as laboratory benchmarks is important to insure that the strong effects of air attenuation are modeled correctly. The modeling presented here is the first attempt at such a characterization of the equipment for flying altitudes. The sodium iodide (NaI) sensors utilized with these systems were characterized using the Monte Carlo N-Particle code (MCNP) developed at Los Alamos National Laboratory. For the fixed wing system, calculations modeled the spectral response for the 3-element NaI detector pod and High-Purity Germanium (HPGe) detector, in the relevant energy range of 50 keV to 3 MeV. NaI detector responses were simulated for both point and distributed surface sources as a function of gamma energy and flying altitude. For point sources, photopeak efficiencies were calculated for a zero radial distance and an offset equal to the altitude. For distributed sources approximating an infinite plane, gross count efficiencies were calculated and normalized to a uniform surface deposition of 1 microCi/m 2 . The helicopter calculations modeled the transport of americium-241 ( 241 Am) as this is

  12. Model reduction of parametrized systems

    CERN Document Server

    Ohlberger, Mario; Patera, Anthony; Rozza, Gianluigi; Urban, Karsten

    2017-01-01

    The special volume offers a global guide to new concepts and approaches concerning the following topics: reduced basis methods, proper orthogonal decomposition, proper generalized decomposition, approximation theory related to model reduction, learning theory and compressed sensing, stochastic and high-dimensional problems, system-theoretic methods, nonlinear model reduction, reduction of coupled problems/multiphysics, optimization and optimal control, state estimation and control, reduced order models and domain decomposition methods, Krylov-subspace and interpolatory methods, and applications to real industrial and complex problems. The book represents the state of the art in the development of reduced order methods. It contains contributions from internationally respected experts, guaranteeing a wide range of expertise and topics. Further, it reflects an important effor t, carried out over the last 12 years, to build a growing research community in this field. Though not a textbook, some of the chapters ca...

  13. Component Reification in Systems Modelling

    DEFF Research Database (Denmark)

    Bendisposto, Jens; Hallerstede, Stefan

    When modelling concurrent or distributed systems in Event-B, we often obtain models where the structure of the connected components is specified by constants. Their behaviour is specified by the non-deterministic choice of event parameters for events that operate on shared variables. From a certain......? These components may still refer to shared variables. Events of these components should not refer to the constants specifying the structure. The non-deterministic choice between these components should not be via parameters. We say the components are reified. We need to address how the reified components get...... reflected into the original model. This reflection should indicate the constraints on how to connect the components....

  14. Computational models of complex systems

    CERN Document Server

    Dabbaghian, Vahid

    2014-01-01

    Computational and mathematical models provide us with the opportunities to investigate the complexities of real world problems. They allow us to apply our best analytical methods to define problems in a clearly mathematical manner and exhaustively test our solutions before committing expensive resources. This is made possible by assuming parameter(s) in a bounded environment, allowing for controllable experimentation, not always possible in live scenarios. For example, simulation of computational models allows the testing of theories in a manner that is both fundamentally deductive and experimental in nature. The main ingredients for such research ideas come from multiple disciplines and the importance of interdisciplinary research is well recognized by the scientific community. This book provides a window to the novel endeavours of the research communities to present their works by highlighting the value of computational modelling as a research tool when investigating complex systems. We hope that the reader...

  15. Peltier cells as temperature control elements: Experimental characterization and modeling

    International Nuclear Information System (INIS)

    Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio

    2014-01-01

    The use of Peltier cells to realize compact and precise temperature controlled devices is under continuous extension in recent years. In order to support the design of temperature control systems, a simplified modeling of heat transfer dynamics for thermoelectric devices is presented. By following a macroscopic approach, the heat flux removed at the cold side of Peltier cell can be expressed as Q . c =γ(T c −T c eq ), where γ is a coefficient dependent on the electric current, T c and T c eq are the actual and steady state cold side temperature, respectively. On the other hand, a microscopic modeling approach was pursued via finite element analysis software packages. To validate the models, an experimental apparatus was designed and build-up, consisting in a sample vial with the surfaces in direct contact with Peltier cells. Both modeling approaches led to reliable prediction of transient and steady state sample temperature. -- Highlights: • Simplified modeling of heat transfer dynamics in Peltier cells. • Coupled macroscopic and microscopic approach. • Experimental apparatus: temperature control of a sample vial. • Both modeling approaches predict accurately the transient and steady state sample temperature

  16. Models of hot stellar systems

    International Nuclear Information System (INIS)

    Van Albada, T.S.

    1986-01-01

    Elliptical galaxies consist almost entirely of stars. Sites of recent star formation are rare, and most stars are believed to be several billion years old, perhaps as old as the Universe itself (--10/sup 10/ yrs). Stellar motions in ellipticals show a modest amount of circulation about the center of the system, but most support against the force of gravity is provided by random motions; for this reason ellipticals are called 'hot' stellar systems. Spiral galaxies usually also contain an appreciable amount of gas (--10%, mainly atomic hydrogen) and new stars are continually being formed out of this gas, especially in the spiral arms. In contrast to ellipticals, support against gravity in spiral galaxies comes almost entirely from rotation; random motions of the stars with respect to rotation are small. Consequently, spiral galaxies are called 'cold' stellar systems. Other than in hot systems, in cold systems the collective response of stars to variations in the force field is an essential part of the dynamics. The present overview is limited to mathematical models of hot systems. Computational methods are also discussed

  17. Aerial measuring system sensor modeling

    International Nuclear Information System (INIS)

    Detwiler, Rebecca

    2002-01-01

    The AMS fixed-wing and rotary-wing systems are critical National Nuclear Security Administration (NNSA) Emergency Response assets. This project is principally focused on the characterization of the sensors utilized with these systems via radiation transport calculations. The Monte Carlo N-Particle code (MCNP) which has been developed at Los Alamos National Laboratory was used to model the detector response of the AMS fixed wing and helicopter systems. To validate the calculations, benchmark measurements were made for simple source-detector configurations. The fixed-wing system is an important tool in response to incidents involving the release of mixed fission products (a commercial power reactor release), the threat or actual explosion of a Radiological Dispersal Device, and the loss or theft of a large industrial source (a radiography source). Calculations modeled the spectral response for the sensors contained, a 3-element NaI detector pod and HpGe detector, in the relevant energy range of 50 keV to 3 MeV. NaI detector responses were simulated for both point and distributed surface sources as a function of gamma energy and flying altitude. For point sources, photo-peak efficiencies were calculated for a zero radial distance and an offset equal to the altitude. For distributed sources approximating infinite plane, gross count efficiencies were calculated and normalized to a uniform surface deposition of 1 C i/m2

  18. Modelling of a Hybrid Energy System for Autonomous Application

    Directory of Open Access Journals (Sweden)

    Yang He

    2013-10-01

    Full Text Available A hybrid energy system (HES is a trending power supply solution for autonomous devices. With the help of an accurate system model, the HES development will be efficient and oriented. In spite of various precise unit models, a HES system is hardly developed. This paper proposes a system modelling approach, which applies the power flux conservation as the governing equation and adapts and modifies unit models of solar cells, piezoelectric generators, a Li-ion battery and a super-capacitor. A generalized power harvest, storage and management strategy is also suggested to adapt to various application scenarios.

  19. Establishment and characterization of equine fibroblast cell lines transformed in vivo and in vitro by BPV-1: Model systems for equine sarcoids

    International Nuclear Information System (INIS)

    Yuan, Z.Q.; Gault, E.A.; Gobeil, P.; Nixon, C.; Campo, M.S.; Nasir, L.

    2008-01-01

    It is now widely recognized that BPV-1 and less commonly BPV-2 are the causative agents of equine sarcoids. Here we present the generation of equine cell lines harboring BPV-1 genomes and expressing viral genes. These lines have been either explanted from sarcoid biopsies or generated in vitro by transfection of primary fibroblasts with BPV-1 DNA. Previously detected BPV-1 genome variations in equine sarcoids are also found in sarcoid cell lines, and only variant BPV-1 genomes can transform equine cells. These equine cell lines are morphologically transformed, proliferate faster than parental cells, have an extended life span and can grow independently of substrate. These characteristics are more marked the higher the level of viral E5, E6 and E7 gene expression. These findings confirm that the virus has an active role in the induction of sarcoids and the lines will be invaluable for further studies on the role of BPV-1 in sarcoid pathology

  20. Mathematical modeling of a zinc/bromine flow cell and a lithium/thionyl chloride primary cell

    Energy Technology Data Exchange (ETDEWEB)

    Evans, T.I.

    1988-01-01

    Three mathematical models are presented, one for the secondary zinc/bromine flow cell and two for the lithium/thionyl chloride primary cell. The objectives in this modeling work are to aid in understanding the physical phenomena affecting cell performance, determine methods of improving cell performance and safety, and reduce the experimental efforts needed to develop these electrochemical systems. The zinc/bromine cell model is the first such model to include a porous layer on the bromine electrode and to predict discharge behavior. The model is used to solve simultaneously the component material balances and the electroneutrality condition for the unknowns, species concentrations and the solution potential. Two models are presented for the lithium/thionyl chloride cell. The first model is a detailed one-dimensional model which is used to solve simultaneously the component material balances, Ohm's law relations, and current balance. The independent design criteria are identified from the model development. The second model presented here is a two-dimensional thermal model for the spirally would configuration of the lithium/thionyl chloride cell. This is the first model to address the effects of the spiral geometry on heat transfer in the cell.

  1. Validation of Embedded System Verification Models

    NARCIS (Netherlands)

    Marincic, J.; Mader, Angelika H.; Wieringa, Roelf J.

    The result of a model-based requirements verification shows that the model of a system satisfies (or not) formalised system requirements. The verification result is correct only if the model represents the system adequately. No matter what modelling technique we use, what precedes the model

  2. Dynamic fuel cell models and their application in hardware in the loop simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lemes, Zijad; Maencher, H. [MAGNUM Automatisierungstechnik GmbH, Bunsenstr. 22, D-64293 Darmstadt (Germany); Vath, Andreas; Hartkopf, Th. [Technische Universitaet Darmstadt/Institut fuer Elektrische Energiewandlung, Landgraf-Georg-Str. 4, D-64283 Darmstadt (Germany)

    2006-03-21

    Currently, fuel cell technology plays an important role in the development of alternative energy converters for mobile, portable and stationary applications. With the help of physical based models of fuel cell systems and appropriate test benches it is possible to design different applications and investigate their stationary and dynamic behaviour. The polymer electrolyte membrane (PEM) fuel cell system model includes gas humidifier, air and hydrogen supply, current converter and a detailed stack model incorporating the physical characteristics of the different layers. In particular, the use of these models together with hardware in the loop (HIL) capable test stands helps to decrease the costs and accelerate the development of fuel cell systems. The interface program provides fast data exchange between the test bench and the physical model of the fuel cell or any other systems in real time. So the flexibility and efficiency of the test bench increase fundamentally, because it is possible to replace real components with their mathematical models. (author)

  3. Endometrial Stromal Cells and Immune Cell Populations Within Lymph Nodes in a Nonhuman Primate Model of Endometriosis

    Science.gov (United States)

    Fazleabas, A. T.; Braundmeier, A. G.; Markham, R.; Fraser, I. S.; Berbic, M.

    2011-01-01

    Mounting evidence suggests that immunological responses may be altered in endometriosis. The baboon (Papio anubis) is generally considered the best model of endometriosis pathogenesis. The objective of the current study was to investigate for the first time immunological changes within uterine and peritoneal draining lymph nodes in a nonhuman primate baboon model of endometriosis. Paraffin-embedded femoral lymph nodes were obtained from 22 normally cycling female baboons (induced endometriosis n = 11; control n = 11). Immunohistochemical staining was performed with antibodies for endometrial stromal cells, T cells, immature and mature dendritic cells, and B cells. Lymph nodes were evaluated using an automated cellular imaging system. Endometrial stromal cells were significantly increased in lymph nodes from animals with induced endometriosis, compared to control animals (P = .033). In animals with induced endometriosis, some lymph node immune cell populations including T cells, dendritic cells and B cells were increased, suggesting an efficient early response or peritoneal drainage. PMID:21617251

  4. Automated Physico-Chemical Cell Model Development through Information Theory

    Energy Technology Data Exchange (ETDEWEB)

    Peter J. Ortoleva

    2005-11-29

    The objective of this project was to develop predictive models of the chemical responses of microbial cells to variations in their surroundings. The application of these models is optimization of environmental remediation and energy-producing biotechnical processes.The principles on which our project is based are as follows: chemical thermodynamics and kinetics; automation of calibration through information theory; integration of multiplex data (e.g. cDNA microarrays, NMR, proteomics), cell modeling, and bifurcation theory to overcome cellular complexity; and the use of multiplex data and information theory to calibrate and run an incomplete model. In this report we review four papers summarizing key findings and a web-enabled, multiple module workflow we have implemented that consists of a set of interoperable systems biology computational modules.

  5. Coal Integrated Gasification Fuel Cell System Study

    Energy Technology Data Exchange (ETDEWEB)

    Chellappa Balan; Debashis Dey; Sukru-Alper Eker; Max Peter; Pavel Sokolov; Greg Wotzak

    2004-01-31

    This study analyzes the performance and economics of power generation systems based on Solid Oxide Fuel Cell (SOFC) technology and fueled by gasified coal. System concepts that integrate a coal gasifier with a SOFC, a gas turbine, and a steam turbine were developed and analyzed for plant sizes in excess of 200 MW. Two alternative integration configurations were selected with projected system efficiency of over 53% on a HHV basis, or about 10 percentage points higher than that of the state-of-the-art Integrated Gasification Combined Cycle (IGCC) systems. The initial cost of both selected configurations was found to be comparable with the IGCC system costs at approximately $1700/kW. An absorption-based CO2 isolation scheme was developed, and its penalty on the system performance and cost was estimated to be less approximately 2.7% and $370/kW. Technology gaps and required engineering development efforts were identified and evaluated.

  6. GCtool for fuel cell systems design and analysis : user documentation.

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R.K.; Geyer, H.K.

    1999-01-15

    GCtool is a comprehensive system design and analysis tool for fuel cell and other power systems. A user can analyze any configuration of component modules and flows under steady-state or dynamic conditions. Component models can be arbitrarily complex in modeling sophistication and new models can be added easily by the user. GCtool also treats arbitrary system constraints over part or all of the system, including the specification of nonlinear objective functions to be minimized subject to nonlinear, equality or inequality constraints. This document describes the essential features of the interpreted language and the window-based GCtool environment. The system components incorporated into GCtool include a gas flow mixer, splitier, heater, compressor, gas turbine, heat exchanger, pump, pipe, diffuser, nozzle, steam drum, feed water heater, combustor, chemical reactor, condenser, fuel cells (proton exchange membrane, solid oxide, phosphoric acid, and molten carbonate), shaft, generator, motor, and methanol steam reformer. Several examples of system analysis at various levels of complexity are presented. Also given are instructions for generating two- and three-dimensional plots of data and the details of interfacing new models to GCtool.

  7. Mathematical Modeling of Constrained Hamiltonian Systems

    NARCIS (Netherlands)

    Schaft, A.J. van der; Maschke, B.M.

    1995-01-01

    Network modelling of unconstrained energy conserving physical systems leads to an intrinsic generalized Hamiltonian formulation of the dynamics. Constrained energy conserving physical systems are directly modelled as implicit Hamiltonian systems with regard to a generalized Dirac structure on the

  8. Testing system for a fuel cells stack

    International Nuclear Information System (INIS)

    Culcer, Mihai; Iliescu, Mariana; Stefanescu, Ioan; Raceanu, Mircea; Enache, Adrian; Lazar, Roxana Elena

    2006-01-01

    Hydrogen and electricity together represent one of the most promising ways to realize sustainable energy, whilst fuel cells provide the most efficient conversion devices for converting hydrogen and possibly other fuels into electricity. Thus, the development of fuel cell technology is currently being actively pursued worldwide. Due to its simple operation and other fair characteristics, the Proton Exchange Membrane Fuel Cell (PEMFC) is especially suitable as a replacement for the internal combustion engine. The PEMFC is also being developed for decentralized electricity and heat generation in buildings and mobile applications. Starting with 2001 the Institute of Research - Development for Cryogenics and Isotopic Technologies - ICIT - Rm. Valcea developed research activities supported by the Romanian Ministry of Education and Research within the National Research Program in order to bridge the gap to European competencies in the area of hydrogen and fuel cells. The paper deals with the testing system designed and developed in ICIT Rm. Valcea as a flexible and versatile tool allowing a large scale of parameter settings and measurements on a single cell or on a fuel cells stack onto a wind range of output power values. (authors)

  9. Radiobiological analyse based on cell cluster models

    International Nuclear Information System (INIS)

    Lin Hui; Jing Jia; Meng Damin; Xu Yuanying; Xu Liangfeng

    2010-01-01

    The influence of cell cluster dimension on EUD and TCP for targeted radionuclide therapy was studied using the radiobiological method. The radiobiological features of tumor with activity-lack in core were evaluated and analyzed by associating EUD, TCP and SF.The results show that EUD will increase with the increase of tumor dimension under the activity homogeneous distribution. If the extra-cellular activity was taken into consideration, the EUD will increase 47%. Under the activity-lack in tumor center and the requirement of TCP=0.90, the α cross-fire influence of 211 At could make up the maximum(48 μm)3 activity-lack for Nucleus source, but(72 μm)3 for Cytoplasm, Cell Surface, Cell and Voxel sources. In clinic,the physician could prefer the suggested dose of Cell Surface source in case of the future of local tumor control for under-dose. Generally TCP could well exhibit the effect difference between under-dose and due-dose, but not between due-dose and over-dose, which makes TCP more suitable for the therapy plan choice. EUD could well exhibit the difference between different models and activity distributions,which makes it more suitable for the research work. When the user uses EUD to study the influence of activity inhomogeneous distribution, one should keep the consistency of the configuration and volume of the former and the latter models. (authors)

  10. Interaction of Defensins with Model Cell Membranes

    Science.gov (United States)

    Sanders, Lori K.; Schmidt, Nathan W.; Yang, Lihua; Mishra, Abhijit; Gordon, Vernita D.; Selsted, Michael E.; Wong, Gerard C. L.

    2009-03-01

    Antimicrobial peptides (AMPs) comprise a key component of innate immunity for a wide range of multicellular organisms. For many AMPs, activity comes from their ability to selectively disrupt and lyse bacterial cell membranes. There are a number of proposed models for this action, but the detailed molecular mechanism of selective membrane permeation remains unclear. Theta defensins are circularized peptides with a high degree of selectivity. We investigate the interaction of model bacterial and eukaryotic cell membranes with theta defensins RTD-1, BTD-7, and compare them to protegrin PG-1, a prototypical AMP, using synchrotron small angle x-ray scattering (SAXS). The relationship between membrane composition and peptide induced changes in membrane curvature and topology is examined. By comparing the membrane phase behavior induced by these different peptides we will discuss the importance of amino acid composition and placement on membrane rearrangement.

  11. The curvature calculation mechanism based on simple cell model.

    Science.gov (United States)

    Yu, Haiyang; Fan, Xingyu; Song, Aiqi

    2017-07-20

    A conclusion has not yet been reached on how exactly the human visual system detects curvature. This paper demonstrates how orientation-selective simple cells can be used to construct curvature-detecting neural units. Through fixed arrangements, multiple plurality cells were constructed to simulate curvature cells with a proportional output to their curvature. In addition, this paper offers a solution to the problem of narrow detection range under fixed resolution by selecting an output value under multiple resolution. Curvature cells can be treated as concrete models of an end-stopped mechanism, and they can be used to further understand "curvature-selective" characteristics and to explain basic psychophysical findings and perceptual phenomena in current studies.

  12. Experimental Characterization and Modeling of PEM Fuel Cells

    DEFF Research Database (Denmark)

    Jespersen, Jesper Lebæk

    fundamental knowledge of the transport and electrochemical processes of PEM fuel cells and to provide methods for obtaining high quality data for PEM fuel cell simulation model validation. In this thesis three different areas of experimental characterization techniques was investigated, they include: Stack...... for obtaining very detailed data of the manifold flow. Moreover, the tools complement each other well, as high quality validation data can be obtained from PIV measurements to verify CFD models. AC Impedance Spectroscopy was used to thoroughly characterize a HTPEM single cell. The measurement method...... was furthermore transferred onto a Labview platform, which signiffcantly improves the exibility and lowers the cost of using this method. This technique is expected to bea very important future tool, used both for material characterization, celldiagnostic, system optimization and as a control input parameter...

  13. Potential of Reversible Solid Oxide Cells as Electricity Storage System

    Directory of Open Access Journals (Sweden)

    Paolo Di Giorgio

    2016-08-01

    Full Text Available Electrical energy storage (EES systems allow shifting the time of electric power generation from that of consumption, and they are expected to play a major role in future electric grids where the share of intermittent renewable energy systems (RES, and especially solar and wind power plants, is planned to increase. No commercially available technology complies with all the required specifications for an efficient and reliable EES system. Reversible solid oxide cells (ReSOC working in both fuel cell and electrolysis modes could be a cost effective and highly efficient EES, but are not yet ready for the market. In fact, using the system in fuel cell mode produces high temperature heat that can be recovered during electrolysis, when a heat source is necessary. Before ReSOCs can be used as EES systems, many problems have to be solved. This paper presents a new ReSOC concept, where the thermal energy produced during fuel cell mode is stored as sensible or latent heat, respectively, in a high density and high specific heat material and in a phase change material (PCM and used during electrolysis operation. The study of two different storage concepts is performed using a lumped parameters ReSOC stack model coupled with a suitable balance of plant. The optimal roundtrip efficiency calculated for both of the configurations studied is not far from 70% and results from a trade-off between the stack roundtrip efficiency and the energy consumed by the auxiliary power systems.

  14. Soluble and cell wall-bound phenolic acids and ferulic acid dehydrodimers in rye flour and five bread model systems: insight into mechanisms of improved availability.

    Science.gov (United States)

    Dynkowska, Wioletta M; Cyran, Malgorzata R; Ceglińska, Alicja

    2015-03-30

    The bread-making process influences bread components, including phenolics that significantly contribute to its antioxidant properties. Five bread model systems made from different rye cultivars were investigated to compare their impact on concentration of ethanol-soluble (free and ester-bound) and insoluble phenolics. Breads produced by a straight dough method without acid addition (A) and three-stage sourdough method with 12 h native starter preparation (C) exhibited the highest, genotype-dependent concentrations of free phenolic acids. Dough acidification by direct acid addition (method B) or by gradual production during prolonged starter fermentation (24 and 48 h, for methods D and E) considerably decreased their level. However, breads B were enriched in soluble ester-bound fraction. Both direct methods, despite substantial differences in dough pH, caused a similar increase in the amount of insoluble ester-bound fraction. The contents of phenolic fractions in rye bread were positively related to activity level of feruloyl esterase and negatively to those of arabinoxylan-hydrolysing enzymes in wholemeal flour. The solubility of rye bread phenolics may be enhanced by application of a suitable bread-making procedure with respect to rye cultivar, as the mechanisms of this process are also governed by a response of an individual genotype with specific biochemical profile. © 2014 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

  15. Modeling of SONOS Memory Cell Erase Cycle

    Science.gov (United States)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat H.

    2011-01-01

    Utilization of Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) nonvolatile semiconductor memories as a flash memory has many advantages. These electrically erasable programmable read-only memories (EEPROMs) utilize low programming voltages, have a high erase/write cycle lifetime, are radiation hardened, and are compatible with high-density scaled CMOS for low power, portable electronics. In this paper, the SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. Comparisons were made between the model predictions and experimental data.

  16. Possibility of hydrogen supply by shared residential fuel cell systems for fuel cell vehicles

    Directory of Open Access Journals (Sweden)

    Ono Yusuke

    2017-01-01

    Full Text Available Residential polymer electrolyte fuel cells cogeneration systems (residential PEFC systems produce hydrogen from city gas by internal gas-reformer, and generate electricity, the hot water at the same time. From the viewpoint of the operation, it is known that residential PEFC systems do not continuously work but stop for long time, because the systems generate enough hot water for short operation time. In other words, currently residential PEFC systems are dominated by the amount of hot water demand. This study focuses on the idle time of residential PEFC systems. Since their gas-reformers are free, the systems have potential to produce hydrogen during the partial load operations. The authors expect that residential PEFC systems can take a role to supply hydrogen for fuel cell vehicles (FCVs before hydrogen fueling stations are distributed enough. From this perspective, the objective of this study is to evaluate the hydrogen production potential of residential PEFC systems. A residential PEFC system was modeled by the mixed integer linear programming to optimize the operation including hydrogen supply for FCV. The objective function represents annual system cost to be minimized with the constraints of energy balance. It should be noted that the partial load characteristics of the gas-reformer and the fuel cell stack are taken into account to derive the optimal operation. The model was employed to estimate the possible amount of hydrogen supply by a residential PEFC system. The results indicated that the system could satisfy at least hydrogen demand for transportation of 8000 km which is as far as the average annual mileage of a passenger car in Japan. Furthermore, hydrogen production by sharing a residential PEFC system with two households is more effective to reduce primary energy consumption with hydrogen supply for FCV than the case of introducing PEFC in each household.

  17. Natural killer (NK) cells inhibit systemic metastasis of glioblastoma cells and have therapeutic effects against glioblastomas in the brain.

    Science.gov (United States)

    Lee, Se Jeong; Kang, Won Young; Yoon, Yeup; Jin, Ju Youn; Song, Hye Jin; Her, Jung Hyun; Kang, Sang Mi; Hwang, Yu Kyeong; Kang, Kyeong Jin; Joo, Kyeung Min; Nam, Do-Hyun

    2015-12-24

    Glioblastoma multiforme (GBM) is characterized by extensive local invasion, which is in contrast with extremely rare systemic metastasis of GBM. Molecular mechanisms inhibiting systemic metastasis of GBM would be a novel therapeutic candidate for GBM in the brain. Patient-derived GBM cells were primarily cultured from surgical samples of GBM patients and were inoculated into the brains of immune deficient BALB/c-nude or NOD-SCID IL2Rgamma(null) (NSG) mice. Human NK cells were isolated from peripheral blood mononucleated cells and expanded in vitro. Patient-derived GBM cells in the brains of NSG mice unexpectedly induced spontaneous lung metastasis although no metastasis was detected in BALB/c-nude mice. Based on the difference of the innate immunity between two mouse strains, NK cell activities of orthotopic GBM xenograft models based on BALB/c-nude mice were inhibited. NK cell inactivation induced spontaneous lung metastasis of GBM cells, which indicated that NK cells inhibit the systemic metastasis. In vitro cytotoxic activities of human NK cells against GBM cells indicated that cytotoxic activity of NK cells against GBM cells prevents systemic metastasis of GBM and that NK cells could be effective cell therapeutics against GBM. Accordingly, NK cells transplanted into orthotopic GBM xenograft models intravenously or intratumorally induced apoptosis of GBM cells in the brain and showed significant therapeutic effects. Our results suggest that innate NK immunity is responsible for rare systemic metastasis of GBM and that sufficient supplementation of NK cells could be a promising immunotherapeutic strategy for GBM in the brain.

  18. Current reprogramming systems in regenerative medicine: from somatic cells to induced pluripotent stem cells.

    Science.gov (United States)

    Hu, Chenxia; Li, Lanjuan

    2016-01-01

    Induced pluripotent stem cells (iPSCs) paved the way for research fields including cell therapy, drug screening, disease modeling and the mechanism of embryonic development. Although iPSC technology has been improved by various delivery systems, direct transduction and small molecule regulation, low reprogramming efficiency and genomic modification steps still inhibit its clinical use. Improvements in current vectors and the exploration of novel vectors are required to balance efficiency and genomic modification for reprogramming. Herein, we set out a comprehensive analysis of current reprogramming systems for the generation of iPSCs from somatic cells. By clarifying advantages and disadvantages of the current reprogramming systems, we are striding toward an effective route to generate clinical grade iPSCs.

  19. Cognitive models embedded in system simulation models

    International Nuclear Information System (INIS)

    Siegel, A.I.; Wolf, J.J.

    1982-01-01

    If we are to discuss and consider cognitive models, we must first come to grips with two questions: (1) What is cognition; (2) What is a model. Presumably, the answers to these questions can provide a basis for defining a cognitive model. Accordingly, this paper first places these two questions into perspective. Then, cognitive models are set within the context of computer simulation models and a number of computer simulations of cognitive processes are described. Finally, pervasive issues are discussed vis-a-vis cognitive modeling in the computer simulation context

  20. Modelling of data acquisition systems

    International Nuclear Information System (INIS)

    Buono, S.; Gaponenko, I.; Jones, R.; Mapelli, L.; Mornacchi, G.; Prigent, D.; Sanchez-Corral, E.; Spiwoks, R.; Skiadelli, M.; Ambrosini, G.

    1994-01-01

    The RD13 project was approved in April 1991 for the development of a scalable data taking system suitable to host various LHC studies. One of its goals is to use simulations as a tool for understanding, evaluating, and constructing different configurations of such data acquisition (DAQ) systems. The RD13 project has developed a modelling framework for this purpose. It is based on MODSIM II, an object-oriented, discrete-event simulation language. A library of DAQ components allows to describe a variety of DAQ architectures and different hardware options in a modular and scalable way. A graphical user interface (GUI) is used to do easy configuration, initialization and on-line monitoring of the simulation program. A tracing facility is used to do flexible off-line analysis of a trace file written at run-time

  1. Glycoengineering in CHO cells: Advances in systems biology

    DEFF Research Database (Denmark)

    Tejwani, Vijay; Andersen, Mikael Rørdam; Nam, Jong Hyun

    2018-01-01

    are not well understood. A systems biology approach combining different technologies is needed for complete understanding of the molecular processes accounting for this variability and to open up new venues in cell line development. In this review, we describe several advances in genetic manipulation, modeling......For several decades, glycoprotein biologics have been successfully produced from Chinese hamster ovary (CHO) cells. The therapeutic efficacy and potency of glycoprotein biologics are often dictated by their post translational modifications, particularly glycosylation, which unlike protein synthesis....... Recently, CHO cells have also been explored for production of therapeutic glycosaminoglycans (e.g. heparin), which presents similar challenges as producing glycoproteins biologics. Approaches to controlling heterogeneity in CHO cells and directing the biosynthetic process toward desired glycoforms...

  2. A mathematical model of collective cell migration in a three-dimensional, heterogeneous environment.

    Directory of Open Access Journals (Sweden)

    David P Stonko

    Full Text Available Cell migration is essential in animal development, homeostasis, and disease progression, but many questions remain unanswered about how this process is controlled. While many kinds of individual cell movements have been characterized, less effort has been directed towards understanding how clusters of cells migrate collectively through heterogeneous, cellular environments. To explore this, we have focused on the migration of the border cells during Drosophila egg development. In this case, a cluster of different cell types coalesce and traverse as a group between large cells, called nurse cells, in the center of the egg chamber. We have developed a new model for this collective cell migration based on the forces of adhesion, repulsion, migration and stochastic fluctuation to generate the movement of discrete cells. We implement the model using Identical Math Cells, or IMCs. IMCs can each represent one biological cell of the system, or can be aggregated using increased adhesion forces to model the dynamics of larger biological cells. The domain of interest is filled with IMCs, each assigned specific biophysical properties to mimic a diversity of cell types. Using this system, we have successfully simulated the migration of the border cell cluster through an environment filled with larger cells, which represent nurse cells. Interestingly, our simulations suggest that the forces utilized in this model are sufficient to produce behaviors of the cluster that are observed in vivo, such as rotation. Our framework was developed to capture a heterogeneous cell population, and our implementation strategy allows for diverse, but precise, initial position specification over a three- dimensional domain. Therefore, we believe that this model will be useful for not only examining aspects of Drosophila oogenesis, but also for modeling other two or three-dimensional systems that have multiple cell types and where investigating the forces between cells is of

  3. A mathematical model of collective cell migration in a three-dimensional, heterogeneous environment.

    Science.gov (United States)

    Stonko, David P; Manning, Lathiena; Starz-Gaiano, Michelle; Peercy, Bradford E

    2015-01-01

    Cell migration is essential in animal development, homeostasis, and disease progression, but many questions remain unanswered about how this process is controlled. While many kinds of individual cell movements have been characterized, less effort has been directed towards understanding how clusters of cells migrate collectively through heterogeneous, cellular environments. To explore this, we have focused on the migration of the border cells during Drosophila egg development. In this case, a cluster of different cell types coalesce and traverse as a group between large cells, called nurse cells, in the center of the egg chamber. We have developed a new model for this collective cell migration based on the forces of adhesion, repulsion, migration and stochastic fluctuation to generate the movement of discrete cells. We implement the model using Identical Math Cells, or IMCs. IMCs can each represent one biological cell of the system, or can be aggregated using increased adhesion forces to model the dynamics of larger biological cells. The domain of interest is filled with IMCs, each assigned specific biophysical properties to mimic a diversity of cell types. Using this system, we have successfully simulated the migration of the border cell cluster through an environment filled with larger cells, which represent nurse cells. Interestingly, our simulations suggest that the forces utilized in this model are sufficient to produce behaviors of the cluster that are observed in vivo, such as rotation. Our framework was developed to capture a heterogeneous cell population, and our implementation strategy allows for diverse, but precise, initial position specification over a three- dimensional domain. Therefore, we believe that this model will be useful for not only examining aspects of Drosophila oogenesis, but also for modeling other two or three-dimensional systems that have multiple cell types and where investigating the forces between cells is of interest.

  4. Discrete dynamic modeling of T cell survival signaling networks

    Science.gov (United States)

    Zhang, Ranran

    2009-03-01

    Biochemistry-based frameworks are often not applicable for the modeling of heterogeneous regulatory systems that are sparsely documented in terms of quantitative information. As an alternative, qualitative models assuming a small set of discrete states are gaining acceptance. This talk will present a discrete dynamic model of the signaling network responsible for the survival and long-term competence of cytotoxic T cells in the blood cancer T-LGL leukemia. We integrated the signaling pathways involved in normal T cell activation and the known deregulations of survival signaling in leukemic T-LGL, and formulated the regulation of each network element as a Boolean (logic) rule. Our model suggests that the persistence of two signals is sufficient to reproduce all known deregulations in leukemic T-LGL. It also indicates the nodes whose inactivity is necessary and sufficient for the reversal of the T-LGL state. We have experimentally validated several model predictions, including: (i) Inhibiting PDGF signaling induces apoptosis in leukemic T-LGL. (ii) Sphingosine kinase 1 and NFκB are essential for the long-term survival of T cells in T-LGL leukemia. (iii) T box expressed in T cells (T-bet) is constitutively activated in the T-LGL state. The model has identified potential therapeutic targets for T-LGL leukemia and can be used for generating long-term competent CTL necessary for tumor and cancer vaccine development. The success of this model, and of other discrete dynamic models, suggests that the organization of signaling networks has an determining role in their dynamics. Reference: R. Zhang, M. V. Shah, J. Yang, S. B. Nyland, X. Liu, J. K. Yun, R. Albert, T. P. Loughran, Jr., Network Model of Survival Signaling in LGL Leukemia, PNAS 105, 16308-16313 (2008).

  5. Solid Oxide Fuel Cell Systems PVL Line

    International Nuclear Information System (INIS)

    Shearer, Susan; Rush, Gregory

    2012-01-01

    In July 2010, Stark State College (SSC), received Grant DE-EE0003229 from the U.S. Department of Energy (DOE), Golden Field Office, for the development of the electrical and control systems, and mechanical commissioning of a unique 20kW scale high-pressure, high temperature, natural gas fueled Stack Block Test System (SBTS). SSC worked closely with subcontractor, Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) over a 13 month period to successfully complete the project activities. This system will be utilized by RRFCS for pre-commercial technology development and training of SSC student interns. In the longer term, when RRFCS is producing commercial products, SSC will utilize the equipment for workforce training. In addition to DOE Hydrogen, Fuel Cells, and Infrastructure Technologies program funding, RRFCS internal funds, funds from the state of Ohio, and funding from the DOE Solid State Energy Conversion Alliance (SECA) program have been utilized to design, develop and commission this equipment. Construction of the SBTS (mechanical components) was performed under a Grant from the State of Ohio through Ohio's Third Frontier program (Grant TECH 08-053). This Ohio program supported development of a system that uses natural gas as a fuel. Funding was provided under the Department of Energy (DOE) Solid