An alternative approach to continuous compliance monitoring and turbine plant optimization using a PEMS (predictive emission monitoring system)

International Nuclear Information System (INIS)

Swanson, B.G.; Lawrence, P.

2009-01-01

This paper reviewed the use of a predictive emissions monitoring system (PEMS) at 3 different gas turbine facilities in the United States and highlighted the costs and benefits of using a PEMS for documenting emissions of priority pollutants and greenhouse gases (GHG). The PEMS interfaces directly to the turbine control system and represents a lower cost alternative to the traditional continuous emission monitoring system (CEMS). The PEMS can track combustion efficiency through modeling of the turbine's operation and emissions. Excess emissions can be tracked and the causes of pollution can be determined and mitigated. The PEMS installed at the 3 turbine plants must meet rigorous performance specification criteria and the sites perform ongoing quality assurance tasks such as periodic audits with portable analyzers. The PEMS is much less expensive to install, operate, and maintain compared to the standard CEMS gas analyzer. Empirical PEMS achieves very high accuracy levels and has demonstrated superior reliability over CEMS for various types of continuous process applications under existing air compliance regulations in the United States. Annual accuracy testing at the gas turbine sites have shown that the PEMS predictions are usually within 5 per cent of the reference method. PEMS can be certified as an alternative to gas analyzer based CEMS for nitrogen oxides and carbon dioxide compliance and for GHG trading purposes. 5 refs., 8 figs.

Primary and secondary electrical space power based on advanced PEM systems

Science.gov (United States)

Vanderborgh, N. E.; Hedstrom, J. C.; Stroh, K. R.; Huff, J. R.

1993-01-01

For new space ventures, power continues to be a pacing function for mission planning and experiment endurance. Although electrochemical power is a well demonstrated space power technology, current hardware limitations impact future mission viability. In order to document and augment electrochemical technology, a series of experiments for the National Aeronautics and Space Administration Lewis Research Center (NASA LeRC) are underway at the Los Alamos National Laboratory that define operational parameters on contemporary proton exchange membrane (PEM) hardware operating with hydrogen and oxygen reactants. Because of the high efficiency possible for water electrolysis, this hardware is also thought part of a secondary battery design built around stored reactants - the so-called regenerative fuel cell. An overview of stack testing at Los Alamos and of analyses related to regenerative fuel cell systems are provided in this paper. Finally, this paper describes work looking at innovative concepts that remove complexity from stack hardware with the specific intent of higher system reliability. This new concept offers the potential for unprecedented electrochemical power system energy densities.

Performance evaluation of an open-cathode PEM fuel cell stack under ambient conditions: Case study of United Arab Emirates

International Nuclear Information System (INIS)

Al-Zeyoudi, Hend; Sasmito, Agus P.; Shamim, Tariq

2015-01-01

Highlights: • Performance evaluation of open-cathode PEM fuel cell stacks with forced air-convection. • Stack performance can vary up to 40% from winter to summer. • Hot and arid condition leads to membrane drying and performance deterioration. • Anode humidification improves the stack performance up to 40% during summer. - Abstract: The open-cathode polymer electrolyte membrane (PEM) fuel cell stack has been a promising candidate as a sustainable energy conversion system for replacing fossil fuel-based energy conversion devices in portable and automotive applications. As the ambient air is directly used to provide both oxidant and cooling, the complex cooling loop can be avoided which reduces the complexity and cost. However, the stack performance is highly affected by ambient conditions, i.e., ambient temperature and humidity. In this study, the effect of monthly ambient air conditions (temperature and humidity) is evaluated with respect to the stack’s power production performance as well as thermal, water and gas management by employing a validated three-dimensional open-cathode PEM fuel cell stack model. The annual climate data from the hot and arid environment of Abu Dhabi, United Arab Emirates (UAE) are used as a case study. The objective is to develop a better fundamental understanding of the interactions of physical phenomena in a fuel cell stack, which can assist in improving the performance and operation of an open-cathode PEM fuel cell-powered vehicle. The results indicate that the stack performance can vary significantly (up to 40%) from winter to summer, especially at high operating currents, with significant changes in the stack temperature and the water content at the membrane. Moreover, the anode humidification results in a significant improvement in the stack performance (up to 40%) in hot and dry conditions. However, a careful balance has to be struck between the humidifier parasitic load and the stack power.

Development of PEM fuel cell stack for small combined heat and power units; Udvikling af PEM braendselscellestak for smaa decentrale kraftvarmeanlaeg

Energy Technology Data Exchange (ETDEWEB)

2008-07-01

The aim of the project was to further develop cells and stack elements in order to reach a higher yield, longer service life, lower production costs and reduced demands for the plants' help, security and SRO (control - regulation - monitoring) systems, i.e. take the PEM fuel cell core technology's yield and cost to a level that will make power generating plants based on PEM fuel cells commercial interesting for CHP production within a capacity area of a few kW. The project focused on development of materials and processes for the individual cell and stack elements, including optimization of materials and production processes for MEAs (membrane electrode assemblies) with integrated diffusion layer, development of materials and production processes for bipolar graphite plates and development of manifold end plates for casting in polymer sandwich construction. (BA)

PORTABLE PEM FUEL CELL SYSTEM: WATER AND HEAT MANAGEMENT

Directory of Open Access Journals (Sweden)

SITI NAJIBAH ABD RAHMAN

2016-07-01

Full Text Available Portable polymer electrolyte membrane (PEM fuel cell power generator is a PEM fuel cell application that is used as an external charger to supply the demand for high energy. Different environments at various ambient temperatures and humidity levels affect the performance of PEM fuel cell power generators. Thermal and water management in portable PEM fuel cells are a critical technical barrier for the commercialization of this technology. The size and weight of the portable PEM fuel cells used for thermal and water management systems that determine the performance of portable PEM fuel cells also need to be considered. The main objective of this paper review was to determine the importance of water and thermal management systems in portable PEM fuel cells. Additionally, this review investigated heat transfer and water transport in PEM fuel cells. Given that portable PEM fuel cells with different powers require different thermal and water management systems, this review also discussed and compared management systems for low-, medium-, and high-power portable PEM fuel cells.

PEM - fuel cell system for residential applications

Energy Technology Data Exchange (ETDEWEB)

Britz, P. [Viessmann Werke GmbH and Co KG, 35107 Allendorf (Germany); Zartenar, N.

2004-12-01

Viessmann is developing a PEM fuel cell system for residential applications. The uncharged PEM fuel cell system has a 2 kW electrical and 3 kW thermal power output. The Viessmann Fuel Processor is characterized by a steam-reformer/burner combination in which the burner supplies the required heat to the steam reformer unit and the burner exhaust gas is used to heat water. Natural gas is used as fuel, which is fed into the reforming reactor after passing an integrated desulphurisation unit. The low temperature (600 C) fuel processor is designed on the basis of steam reforming technology. For carbon monoxide removal, a single shift reactor and selective methanisation is used with noble metal catalysts on monoliths. In the shift reactor, carbon monoxide is converted into hydrogen by the water gas shift reaction. The low level of carbon monoxide at the outlet of the shift reactor is further reduced, to approximately 20 ppm, downstream in the methanisation reactor, to meet PEM fuel cell requirements. Since both catalysts work at the same temperature (240 C), there is no requirement for an additional heat exchanger in the fuel processor. Start up time is less than 30 min. In addition, Viessmann has developed a 2 kW class PEFC stack, without humidification. Reformate and dry air are fed straight to the stack. Due to the dry operation, water produced by the cell reaction rapidly diffuses through the electrolyte membrane. This was achieved by optimising the MEA, the gas flow pattern and the operating conditions. The cathode is operated by an air blower. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Study of a SOFC-PEM hybrid system

International Nuclear Information System (INIS)

Fillman, B.; Bjornbom, P.; Sylwan, C.

2004-01-01

'Full text:' In the present project a system study of a SOFC-PEM hybrid system is in progress. Positive synergy effects are expected when combining a SOFC system with a PEM system. By combining the advantages of each fuel cell type it is promising that the hybrid system has higher overall efficiency than a SOFC-only system or a reformer-PEM system. A SOFC stack produces electricity and a reformate gas that can be further processed to hydrogen by the shift reaction. The produced hydrogen can be used by PEM stack in order to produce further electricity. In the PEM system case the complex fuel reformer processing could be eliminated. The simulations were performed with the flowsheeting simulation software Aspen Plus. (author)

Durability of PEM Fuel Cell Membranes

Science.gov (United States)

Huang, Xinyu; Reifsnider, Ken

Durability is still a critical limiting factor for the commercialization of polymer electrolyte membrane (PEM) fuel cells, a leading energy conversion technology for powering future hydrogen fueled automobiles, backup power systems (e.g., for base transceiver station of cellular networks), portable electronic devices, etc. Ionic conducting polymer (ionomer) electrolyte membranes are the critical enabling materials for the PEM fuel cells. They are also widely used as the central functional elements in hydrogen generation (e.g., electrolyzers), membrane cell for chlor-alkali production, etc. A perfluorosulfonic acid (PFSA) polymer with the trade name Nafion® developed by DuPont™ is the most widely used PEM in chlor-alkali cells and PEM fuel cells. Similar PFSA membranes have been developed by Dow Chemical, Asahi Glass, and lately Solvay Solexis. Frequently, such membranes serve the dual function of reactant separation and selective ionic conduction between two otherwise separate compartments. For some applications, the compromise of the "separation" function via the degradation and mechanical failure of the electrolyte membrane can be the life-limiting factor; this is particularly the case for PEM in hydrogen/oxygen fuel cells.

Investigation of a novel concept for hydrogen production by PEM water electrolysis integrated with multi-junction solar cells

International Nuclear Information System (INIS)

Ferrero, Domenico; Santarelli, Massimo

2017-01-01

Highlights: • A 2D model of a PEM water electrolyzer is developed and validated. • A novel system integrating PEM and multi-junction solar cells is proposed. • The model is applied to the simulation of the novel system. • The integration of PEM and MJ cells enhances the hydrogen production efficiency. - Abstract: A 2D finite element model of a high-pressure PEM water electrolyzer is developed and validated over experimental data obtained from a demonstration prototype. The model includes the electrochemical, fluidic and thermal description of the repeating unit of a PEM electrolyzer stack. The model is applied to the simulation of a novel system composed by a high-temperature, high-pressure PEM electrochemical cell coupled with a photovoltaic multi-junction solar cell installed in a solar concentrator. The thermo-electrochemical characterization of the solar-driven PEM electrolysis system is presented and the advantages of the high-temperature operation and of the direct coupling of electrolyzer and solar cell are assessed. The results show that the integration of the multi-junction cell enhances the performance of the electrolyzer and allows to achieve higher system efficiency compared to separated photovoltaic generation and hydrogen production by electrolysis.

PEM fuel cells thermal and water management fundamentals

CERN Document Server

Wang, Yun; Cho, Sung Chan

2014-01-01

Polymer Electrolyte Membrane (PEM) fuel cells convert chemical energy in hydrogen into electrical energy with water as the only by-product. Thus, PEM fuel cells hold great promise to reduce both pollutant emissions and dependency on fossil fuels, especially for transportation-passenger cars, utility vehicles, and buses-and small-scale stationary and portable power generators. But one of the greatest challenges to realizing the high efficiency and zero emissions potential of PEM fuel cells technology is heat and water management. This book provides an introduction to the essential concepts for effective thermal and water management in PEM fuel cells and an assessment on the current status of fundamental research in this field. The book offers you: An overview of current energy and environmental challenges and their imperatives for the development of renewable energy resources, including discussion of the role of PEM fuel cells in addressing these issues; Reviews of basic principles pertaining to PEM fuel cel...

Reliability analysis and utilization of PEMs in space application

Science.gov (United States)

Jiang, Xiujie; Wang, Zhihua; Sun, Huixian; Chen, Xiaomin; Zhao, Tianlin; Yu, Guanghua; Zhou, Changyi

2009-11-01

More and more plastic encapsulated microcircuits (PEMs) are used in space missions to achieve high performance. Since PEMs are designed for use in terrestrial operating conditions, the successful usage of PEMs in space harsh environment is closely related to reliability issues, which should be considered firstly. However, there is no ready-made methodology for PEMs in space applications. This paper discusses the reliability for the usage of PEMs in space. This reliability analysis can be divided into five categories: radiation test, radiation hardness, screening test, reliability calculation and reliability assessment. One case study is also presented to illuminate the details of the process, in which a PEM part is used in a joint space program Double-Star Project between the European Space Agency (ESA) and China. The influence of environmental constrains including radiation, humidity, temperature and mechanics on the PEM part has been considered. Both Double-Star Project satellites are still running well in space now.

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...

Full-scale demonstration of EBS construction technology II. Design, manufacturing and transportation of pre-fabricated EBS module (PEM)

International Nuclear Information System (INIS)

Asano, Hidekazu; Toguri, Satohito; Iwata, Yumiko; Kawakami, Susumu; Nagasawa, Yuji; Yoshida, Takeshi

2008-01-01

PEM was investigated as a full-scale demonstration for the design, manufacturing and construction by using simulated buffer material and overpack in consideration of horizontal emplacement. Also near full-scale tests were conducted to examine the applicability of air-bearing system which can be used to transport a heavy load at the drift tunnel as for PEM. With regard to PEM casing, design requirements were selected from the viewpoints of EBS performance and operation safety issues. The construction procedure was examined in consideration of the shapes of buffer material, which are previously positioned inside the casing. And design procedure of the casing was also examined and presented. A full-scale PEM casing as a longitudinally two-part divided cylinder type with connection flanges was manufactured by using carbon steel plate. The wall thickness of this non-leak tight type PEM casing was evaluated its mechanical integrity by 2-dimensional stress analysis in consideration of the emplacement condition on the drift tunnel basement. Mechanical integrity of a percolated type casing was also examined its mechanical integrity. Air-bearing unit, which originally apply to a flat/smooth surface, was modified to fit a curved surface of the drift tunnel. Two units were aligned with two parallel lines, which estimate to be able to lift 12 tons, about two-fifth of the total weight of full scale PEM. On the conducted transportation tests of the air-bearing units, considering the surface roughness of the drift tunnel, especially for its unevenness, capability and availability of the run-over such gaps were investigated. And effect of covering sheets which can improve the gapped surface into relatively smooth was also examined by using several candidate materials. Through these tests, combination of the covering sheets and the maximum available height difference were evaluated and identified. Also the maximum traction force to toe the loading was measured to design the air

Reconstruction of Clear-PEM data with STIR

CERN Document Server

Martins, M V; Rodrigues, P; Trindade, A; Oliveira, N; Correia, M; Cordeiro, H; Ferreira, N C; Varela, J; Almeida, P

2006-01-01

The Clear-PEM scanner is a device based on planar detectors that is currently under development within the Crystal Clear Collaboration, at CERN. The basis for 3D image reconstruction in Clear-PEM is the software for tomographic image reconstruction (STIR). STIR is an open source object-oriented library that efficiently deals with the 3D positron emission tomography data sets. This library was originally designed for the traditional cylindrical scanners. In order to make its use compatible with planar scanner data, new functionalities were introduced into the library's framework. In this work, Monte Carlo simulations of the Clear-PEM scanner acquisitions were used as input for image reconstruction with the 3D OSEM algorithm available in STIR. The results presented indicate that dual plate PEM data can be accurately reconstructed using the enhanced STIR framework.

Development of advanced PEM water electrolysers

International Nuclear Information System (INIS)

A Deschamps; C Etievant; C Puyenchet; V Fateev; S Grigoriev; A Kalinnikov; V Porembsky; P Millet

2006-01-01

Concerning the production of electrolytic hydrogen, the goal of present R and D is to develop advanced hydrogen generator based on proton exchange membrane (PEM) water electrolysers. PEM-based water electrolysis offers a number of advantages, such as ecological safety, high gas purity (more than 99.99% for hydrogen), the possibility of producing compressed gases (up to 200 bar) for direct pressurized storage without additional power inputs, etc. PEM electrolysers are considered as rather attractive devices to accelerate the transition to the hydrogen economy and develop a hydrogen infrastructure network (for example for the development of re-filling stations for cars, using electric power stations at night hours and renewable energy sources). The work presented here result from a cooperation between Hydrogen Energy and Plasma Technology Institute (HEPTI) of Russian Research Center (RRC) 'Kurchatov Institute', Universite Paris - Sud XI and Compagnie d'Etudes des Technologies de l'Hydrogene. This project is supported by the Commission of the European Communities within the frame of the 6. Framework Programme (GenHyPEM, STREP no 019802). (authors)

GenHyPEM: A research program on PEM water electrolysis supported by the European Commission

Energy Technology Data Exchange (ETDEWEB)

Millet, Pierre; Dragoe, Diana [Institut de Chimie Moleculaire et des Materiaux d' Orsay, UMR CNRS no 8182, Universite Paris-Sud 11, 15 rue Georges Clemenceau, 91405 Orsay Cedex (France); Grigoriev, Serguey; Fateev, Vladimir [Hydrogen Energy and Plasma Technology, Institute of Russian Research Center, Kurchatov Institute, 1, Kurchatov sq., 123182 Moscow (Russian Federation); Etievant, Claude [Compagnie Europeenne des Technologies de l' Hydrogene (CETH), Innov' Valley Entreprise, Batiment D0, Route de Nozay, 91461 Marcoussis Cedex (France)

2009-06-15

GenHyPEM (Generateur d'Hydrogene par electrolyse de l'eau PEM <>) is an STREP programme (no 019802) supported by the European Commission in the course of the 6th framework research programme. This R and D project which started in October 2005, is a 2.6 MEUR research effort over three years. It gathers partners from Belgium, Germany, Romania, Federation of Russia, Armenia and France. The main goal of the project is to develop low-cost and high pressure (50 bar) PEM water electrolysers for the production of up to several Nm{sup 3} H{sub 2}/h. The purpose of this communication is to present the current status of GenHyPEM. Major results and technological achievements obtained so far in the fields of academic (electrocatalysis, polymer electrolyte) and applied (stack development and performances) research are presented. Non-noble electrocatalysts have been identified to replace platinum for the HER and stable performances have been obtained during operation at high (1 A cm{sup -2}) current density, paving the way to substantial cost reductions. Prototype electrolysers producing from 0.1 to 5 Nm{sup 3} H{sub 2}/h have been successfully developed. (author)

California dreaming?[PEM stacks

Energy Technology Data Exchange (ETDEWEB)

Crosse, J.

2002-06-01

Hyundai's Santa Fe FCEV will be on sale by the end of 2002. Hyundai uses PEM stacks that are manufactured by International Fuel Cells (IFC), a division of United Technologies. Santa Fe is equipped with a 65 kW electric powertrain of Enova systems and Shell's new gasoline reformer called Hydrogen Source. Eugene Jang, Senior Engineer - Fuel Cell and Materials at Hyundai stated that the compressor related losses on IFC system are below 3%. The maximum speed offered by the vehicle is estimated as 123km/hr while the petrol equivalent fuel consumption is quoted between 5.6L/100 km and 4.8L/100 km. Santa Fe is a compact vehicle offering better steering response and a pleasant drive. (author)

UARS PEM Level 2 AXIS 2 V001 (UARPE2AXIS2) at GES DISC

Data.gov (United States)

National Aeronautics and Space Administration — The UARS Particle Environment Monitor (PEM) level 2 Atmosphere X-Ray Imaging Spectrometer (AXIS) unit 2 daily product contains the X-ray high-resolution spectral...

UARS PEM Level 2 AXIS 1 V001 (UARPE2AXIS1) at GES DISC

Data.gov (United States)

National Aeronautics and Space Administration — The UARS Particle Environment Monitor (PEM) level 2 Atmosphere X-Ray Imaging Spectrometer (AXIS) unit 1 daily product contains the X-ray high-resolution spectral...

Predictive emission monitoring system (PEMS) for emission control in biomass fired plants; Predikterande emissionsmaetsystem (PEMS) foer emissionskontroll i biobraensleeldade foerbraenningsanlaeggningar

Energy Technology Data Exchange (ETDEWEB)

Harnevie, H; Sarkoezi, L; Trenkle, S

1996-08-01

An alternative method for estimation of NO{sub x}-emissions from biomass fired plants has been investigated. The method, `Predictive emission monitoring` (PEMS), implicates the creation of a mathematical formula. The formula expresses the relations between NO{sub x}-emissions and various operating and external parameters, such as flue gas temperature, excess combustion air and heat load. In this study the applicability of PEMS has been tested for two plants both of type travelling stokers. The most important results of the study are: PEMS is suitable for emission monitoring for some types of biomass fired plants (for example travelling stokers) even if the plant is fired with fuel with varying water content. In most cases it should be sufficient if the relation is based on oxygen level in the flue gas and plant load, with the possible addition of flue gas temperature and/or furnace temperature rate. These parameters are usually measured in any case, which means that no additional investment in instrumentation is necessary. In this study many measured parameters (for example the throttle levels) did not affect the NO{sub x}-emissions. A PEMS relation is only applicable for a specific plant and for a fixed validity range. Thus the function should be performed in such a way that it covers the limits of the operating parameters of the plant. Usage of different fuels or drift optimization can only be done within the validity range. Good combustion conditions could be necessary to receive a usable PEMS-function. Before creating the PEMS-function the combustion and the emission levels must be optimized. In plants with very fluctuating combustion, for example fixed stokers, it is possible that PEMS leads to not satisfying results. The total cost for a PEM-function can be calculated to be about 50-70% compared to a CEM during a period of a decade. 8 refs, 13 figs, 15 tabs, 8 appendices

Experimental characterization of the Clear-PEM scanner spectrometric performance

Energy Technology Data Exchange (ETDEWEB)

Bugalho, R; Carrico, B; Ferreira, C S; Frade, M; Ferreira, M; Moura, R; Ortigao, C; Pinheiro, J F; Rodrigues, P; Rolo, I; Silva, J C; Trindade, A; Varela, J [Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Av. Elias Garcia 14-1, 1000-149 Lisboa (Portugal)], E-mail: frade@lip.pt

2009-10-15

In the framework of the Clear-PEM project for the construction of a high-resolution and high-specificity scanner for breast cancer imaging, a Positron Emission Mammography tomograph has been developed and installed at the Instituto Portugues de Oncologia do Porto hospital. The Clear-PEM scanner is mainly composed by two planar detector heads attached to a robotic arm, trigger/data acquisition electronics system and computing servers. The detector heads hold crystal matrices built from 2 x 2 x 20 mm{sup 3} LYSO:Ce crystals readout by Hamamatsu S8550 APD arrays. The APDs are optically coupled to both ends of the 6144 crystals in order to extract the DOI information for each detected event. Each one of 12288 APD's pixels is read and controlled by Application Specific Integrated Circuits water-cooled by an external cooling unit. The Clear-PEM frontend boards innovative design results in a unprecedented integration of the crystal matrices, APDs and ASICs, making Clear-PEM the PET scanner with the highest number of APD pixels ever integrated so far. In this paper, the scanner's main technical characteristics, calibration strategies and the first spectrometric performance evaluation in a clinical environment are presented. The first commissioning results show 99.7% active channels, which, after calibration, have inter-pixel and absolute gain distributions with dispersions of, respectively, 12.2% and 15.3%, demonstrating that despite the large number of channels, the system is uniform. The mean energy resolution at 511 keV is of 15.9%, with a 8.8% dispersion, and the mean C{sub DOI}{sup -1} is 5.9%/mm, with a 7.8% dispersion. The coincidence time resolution, at 511 keV, for a energy window between 400 and 600 keV, is 5.2 ns FWHM.

Closed-Cycle Hydrogen-Oxygen Regenerative Fuel Cell at the NASA Glenn Research Center-An Update

Science.gov (United States)

Bents, David J.; Chang, Bei-Jiann; Johnson, Donald W.; Garcia, Christopher P.

2008-01-01

The closed cycle hydrogen-oxygen proton exchange membrane (PEM) regenerative fuel cell (RFC) at the NASA Glenn Research Center has demonstrated multiple back-to-back contiguous cycles at rated power and round-trip efficiencies up to 52 percent. It is the first fully closed cycle RFC ever demonstrated. (The entire system is sealed; nothing enters or escapes the system other than electrical power and heat.) During fiscal year fiscal year (FY) FY06 to FY07, the system s numerous modifications and internal improvements focused on reducing parasitic power, heat loss, and noise signature; increasing its functionality as an unattended automated energy storage device; and in-service reliability.

Method of monitoring CO concentrations in hydrogen feed to a PEM fuel cell

Science.gov (United States)

Grot, Stephen Andreas; Meltser, Mark Alexander; Gutowski, Stanley; Neutzler, Jay Kevin; Borup, Rodney Lynn; Weisbrod, Kirk

2000-01-01

The CO concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and/or voltage behavior patterns from a PEM-probe communicating with the reformate feed stream. Pattern recognition software may be used to compare the current and voltage patterns from the PEM-probe to current and voltage telltale outputs determined from a reference cell similar to the PEM-probe and operated under controlled conditions over a wide range of CO concentrations in the H.sub.2 fuel stream. The PEM-probe is intermittently purged of any CO build-up on the anode catalyst (e.g., by (1) flushing the anode with air, (2) short circuiting the PEM-probe, or (3) reverse biasing the PEM-probe) to keep the PEM-probe at peak performance levels.

Performance optimization of a PEM hydrogen-oxygen fuel cell

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

The objective was to develop a semi-empirical model that would simulate the performance of proton exchange membrane (PEM) fuel cells without extensive calculations. A fuel cell mathematical module has been designed and constructed to determine the performance of a PEM fuel cell. The influence of some operating parameters on the performance of PEM fuel cell has been investigated using pure hydrogen on the anode side and oxygen on the cathode side. The present model can be used to investigate the influence of process variables for design optimization of fuel cells, stacks, and complete fuel cell power system. The possible mechanisms of the parameter effects and their interrelationships are discussed. In order to assess the validity of the developed model a real PEM fuel cell system has been used to generate experimental data. The comparison shows good agreements between the modelling results and the experimental data. The model is shown a very useful for estimating the performance of PEM fuel cell stacks and optimization of fuel cell system integration and operation.

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.

Clear-PEM: A dedicated PET camera for improved breast cancer detection

International Nuclear Information System (INIS)

Abreu, M. C.; Almeida, P.; Balau, F.; Ferreira, N. C.; Fetal, S.; Fraga, F.; Martins, M.; Matela, N.; Moura, R.; Ortigao, C.; Peralta, L.; Rato, P.; Ribeiro, R.; Rodrigues, P.; Santos, A. I.; Trindade, A.; Varela, J.

2005-01-01

Positron emission mammography (PEM) can offer a non-invasive method for the diagnosis of breast cancer. Metabolic images from PEM using 18 F-fluoro-deoxy-glucose, contain unique information not available from conventional morphologic imaging techniques like X-ray radiography. In this work, the concept of Clear-PEM, the system presently developed in the frame of the Crystal Clear Collaboration at CERN, is described. Clear-PEM will be a dedicated scanner, offering better perspectives in terms of position resolution and detection sensitivity. (authors)

Performance optimization of a PEM hydrogen-oxygen fuel cell

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2013-01-01

The objective was to develop a semi-empirical model that would simulate the performance of proton exchange membrane (PEM) fuel cells without extensive calculations. A fuel cell mathematical module has been designed and constructed to determine the performance of a PEM fuel cell. The influence of some operating parameters on the performance of PEM fuel cell has been investigated using pure hydrogen on the anode side and oxygen on the cathode side. The present model can be used to investigate t...

Regenerative agriculture: merging farming and natural resource conservation profitably.

Science.gov (United States)

LaCanne, Claire E; Lundgren, Jonathan G

2018-01-01

Most cropland in the United States is characterized by large monocultures, whose productivity is maintained through a strong reliance on costly tillage, external fertilizers, and pesticides (Schipanski et al., 2016). Despite this, farmers have developed a regenerative model of farm production that promotes soil health and biodiversity, while producing nutrient-dense farm products profitably. Little work has focused on the relative costs and benefits of novel regenerative farming operations, which necessitates studying in situ , farmer-defined best management practices. Here, we evaluate the relative effects of regenerative and conventional corn production systems on pest management services, soil conservation, and farmer profitability and productivity throughout the Northern Plains of the United States. Regenerative farming systems provided greater ecosystem services and profitability for farmers than an input-intensive model of corn production. Pests were 10-fold more abundant in insecticide-treated corn fields than on insecticide-free regenerative farms, indicating that farmers who proactively design pest-resilient food systems outperform farmers that react to pests chemically. Regenerative fields had 29% lower grain production but 78% higher profits over traditional corn production systems. Profit was positively correlated with the particulate organic matter of the soil, not yield. These results provide the basis for dialogue on ecologically based farming systems that could be used to simultaneously produce food while conserving our natural resource base: two factors that are pitted against one another in simplified food production systems. To attain this requires a systems-level shift on the farm; simply applying individual regenerative practices within the current production model will not likely produce the documented results.

Thermal stability control system of photo-elastic interferometer in the PEM-FTs

Science.gov (United States)

Zhang, M. J.; Jing, N.; Li, K. W.; Wang, Z. B.

2018-01-01

A drifting model for the resonant frequency and retardation amplitude of a photo-elastic modulator (PEM) in the photo-elastic modulated Fourier transform spectrometer (PEM-FTs) is presented. A multi-parameter broadband-matching driving control method is proposed to improve the thermal stability of the PEM interferometer. The automatically frequency-modulated technology of the driving signal based on digital phase-locked technology is used to track the PEM's changing resonant frequency. Simultaneously the maximum optical-path-difference of a laser's interferogram is measured to adjust the amplitude of the PEM's driving signal so that the spectral resolution is stable. In the experiment, the multi-parameter broadband-matching control method is applied to the driving control system of the PEM-FTs. Control of resonant frequency and retardation amplitude stabilizes the maximum optical-path-difference to approximately 236 μm and results in a spectral resolution of 42 cm-1. This corresponds to a relative error smaller than 2.16% (4.28 standard deviation). The experiment shows that the method can effectively stabilize the spectral resolution of the PEM-FTs.

PEM-fuel cells for mobile application. Sub task: development of electrocatalysts. Final report; PEM-Brennstoffzelle fuer mobile Anwendung. Teilprojekt: Katalysatorenentwicklung. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Starz, K A

1999-01-01

PEM fuel cells are gaining increasing importance for use in automotive application. The goal of the research program reported here was to develop the basic technology and components for PEMFC stacks for use in transport applications. The sub-task of Degussa was to develop improved electrocatalysts for PEMFC single cells and stacks. The technical objectives of the research project were met. Electrocatalysts, characterized by a high Pt-dispersion, high surface area and excellent activity, were developed. With this material, considerable progress was made to reduce the total platinum loading of PEMFC cells and stacks to about 0,5 mgPt/cm{sup 2}. With this value, the goal of the program (<0,8 mg/cm{sup 2}) was significantly surpassed. Additionally, higher power densities of >0.4 W/cm{sup 2} were achieved at Degussa for hydrogen/air and reformate/air operation of the PEMFC. A CO-tolerant anode electrocatalyst, exhibiting a CO-tolerance of up to 100 ppm CO, enables the operation of PEMFC stacks with on-board generated methanol reformate. The performance of the new electrocatalyst materials was verified by DaimlerChrysler in a PEMFC demonstration stack at the end of the program. (orig.) [Deutsch] PEM-Brennstoffzellen gewinnen fuer die mobile Anwendung immer mehr an Bedeutung. Im Rahmen des hier beschriebenen Leitprojektes sollten die Basistechnologien fuer den Einsatz der PEM-Brennstoffzelle im mobilen Bereich (Elektrotraktion) entwickelt werden. Das Teilprojekt der Degussa befasst sich mit der Entwicklung von verbesserten Elektrokatalysatoren fuer PEM-Brennstoffzellenstacks. Die technischen Arbeitsziele des Vorhabens wurden erreicht. So konnten Elektrokatalysatoren bereitgestellt werden, die sich durch eine hohe Pt-Dispersion, eine grosse Pt-Oberflaeche sowie eine sehr gute Aktivitaet auszeichnen. Mit diesen Elektrokatalysatoren gelang es, die Platinbeladung der PEM-Elektroden (Anode und Kathode) erheblich abzusenken. Mit einer Gesamtplatinbeladung von 0,5 mg/cm{sup 2

Parameterization of electrical equivalent circuits for pem fuel cells; Parametrierung elektrischer Aequivalentschaltbilder von PEM Brennstoffzellen

Energy Technology Data Exchange (ETDEWEB)

Haubrock, J.

2007-12-13

Fuel cells are a very promising technology for energy conversion. For optimization purpose, useful simulation tools are needs. Simulation tools should simulate the static and dynamic electrical behaviour and the models should parameterized by measurment results which should be done easily. In this dissertation, a useful model for simulating a pem fuel cell is developed. the model should parametrizes by V-I curve measurment and by current step respond. The model based on electrical equivalent circuits and it is shown, that it is possible to simulate the dynamic behaviour of a pem fuel cell stack. The simulation results are compared by measurment results. (orig.)

Clear-PEM, a dedicated PET camera for mammography

CERN Document Server

Lecoq, P

2002-01-01

Preliminary results suggest that Positron Emission Mammography (PEM) can offer a noninvasive method for the diagnosis of breast cancer. Metabolic images from PEM contain unique information not available from conventional morphologic imaging techniques and aid in expeditiously establishing the diagnosis of cancer. A dedicated machine seems to offer better perspectives in terms of position resolution and sensitivity. This paper describes the concept of Clear-PEM, the system presently developed by the Crystal Clear Collaboration at CERN for an evaluation of this approach. This device is based on new crystals introduced by the Crystal Clear as well as on modern data acquisition techniques developed for the large experiments in high energy physics experiments.

Investigation of low glass transition temperature on COTS PEMs reliability

Science.gov (United States)

Sandor, M.; Agarwal, S.

2002-01-01

Many factors influence PEM component reliability.One of the factors that can affect PEM performance and reliability is the glass transition temperature (Tg) and the coefficient of thermal expansion (CTE) of the encapsulant or underfill. JPL/NASA is investigating how the Tg and CTE for PEMs affect device reliability under different temperature and aging conditions. Other issues with Tg are also being investigated. Some preliminary data will be presented on glass transition temperature test results conducted at JPL.

Detailed experimental characterization of a reformate fuelled PEM stack

DEFF Research Database (Denmark)

Korsgaard, Anders; Nielsen, Mads Pagh; Kær, Søren Knudsen

2006-01-01

Increasing attention is given to fuel cells for micro combined heat and power systems for local households. Currently, mainly three different types of fuel cells are commercially competitive: SOFC, low- and high-temperature PEM fuel cells. In the present paper the Low Temperature PEM technology i...

Comparative energy analysis on a new regenerative Brayton cycle

International Nuclear Information System (INIS)

Goodarzi, M.

2016-01-01

Highlights: • New regenerative Brayton cycle has been introduced. • New cycle has higher thermal efficiency and lower exhausted heat per output power. • Regenerator may remain useful in the new cycle even at high pressure ratio. • New regenerative Brayton cycle is suggested for low pressure ratio operations. - Abstract: Gas turbines are frequently used for power generation. Brayton cycle is the basis for gas turbine operation and developing the alternative cycles. Regenerative Brayton cycle is a developed cycle for basic Brayton cycle with higher thermal efficiency at low to moderate pressure ratios. A new regenerative Brayton cycle has been introduced in the present study. Energy analysis has been conducted on ideal cycles to compare them from the first law of thermodynamics viewpoint. Comparative analyses showed that the new regenerative Brayton cycle has higher thermal efficiency than the original one at the same pressure ratio, and also lower heat absorption and exhausted heat per unite output power. Computed results show that new cycle improves thermal efficiency from 12% to 26% relative to the original regenerative Brayton cycle in the range of studied pressure ratios. Contrary to the original regenerative Brayton cycle, regenerator remains useful in the new regenerative Brayton cycle even at higher pressure ratio.

Building a Predictive Capability for Decision-Making that Supports MultiPEM

Energy Technology Data Exchange (ETDEWEB)

Carmichael, Joshua Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-20

Multi-phenomenological explosion monitoring (multiPEM) is a developing science that uses multiple geophysical signatures of explosions to better identify and characterize their sources. MultiPEM researchers seek to integrate explosion signatures together to provide stronger detection, parameter estimation, or screening capabilities between different sources or processes. This talk will address forming a predictive capability for screening waveform explosion signatures to support multiPEM.

Development of PEM fuel cell technology at international fuel cells

Energy Technology Data Exchange (ETDEWEB)

Wheeler, D.J.

1996-04-01

The PEM technology has not developed to the level of phosphoric acid fuel cells. Several factors have held the technology development back such as high membrane cost, sensitivity of PEM fuel cells to low level of carbon monoxide impurities, the requirement to maintain full humidification of the cell, and the need to pressurize the fuel cell in order to achieve the performance targets. International Fuel Cells has identified a hydrogen fueled PEM fuel cell concept that leverages recent research advances to overcome major economic and technical obstacles.

SPE (tm) regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications

Science.gov (United States)

Mcelroy, J. F.

1990-01-01

Viewgraphs on SPE regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications are presented. Topics covered include: hydrogen-oxygen regenerative fuel cell energy storage system; electrochemical cell reactions; SPE cell voltage stability; passive water removal SPE fuel cell; fuel cell performance; SPE water electrolyzers; hydrophobic oxygen phase separator; hydrophilic/electrochemical hydrogen phase separator; and unitized regenerative fuel cell.

The JPL Direct Methanol Liquid-feed PEM Fuel Cell

Science.gov (United States)

Halpert, G.; Surampudi, S.

1994-01-01

Recently, there has been a breakthrough in fuel cell technology in the Energy Storage Systems Group at the Jet Propulsion Laboratory with the develpment of a direct methanol, liquid-feed, solid polymer electrolyte membrane (PEM) fuel cell... The methanol liquid-feed, solid polymer electrolyte (PEM) design has numerous system level advantages over the gas-feed design. These include:...

Development of ClearPEM-Sonic, a multimodal mammography system for PET and Ultrasound

Science.gov (United States)

Cucciati, G.; Auffray, E.; Bugalho, R.; Cao, L.; Di Vara, N.; Farina, F.; Felix, N.; Frisch, B.; Ghezzi, A.; Juhan, V.; Jun, D.; Lasaygues, P.; Lecoq, P.; Mensah, S.; Mundler, O.; Neves, J.; Paganoni, M.; Peter, J.; Pizzichemi, M.; Siles, P.; Silva, J. C.; Silva, R.; Tavernier, S.; Tessonnier, L.; Varela, J.

2014-03-01

ClearPEM-Sonic is an innovative imaging device specifically developed for breast cancer. The possibility to work in PEM-Ultrasound multimodality allows to obtain metabolic and morphological information increasing the specificity of the exam. The ClearPEM detector is developed to maximize the sensitivity and the spatial resolution as compared to Whole-Body PET scanners. It is coupled with a 3D ultrasound system, the SuperSonic Imagine Aixplorer that improves the specificity of the exam by providing a tissue elasticity map. This work describes the ClearPEM-Sonic project focusing on the technological developments it has required, the technical merits (and limits) and the first multimodal images acquired on a dedicated phantom. It finally presents selected clinical case studies that confirm the value of PEM information.

Development of ClearPEM-Sonic, a multimodal mammography system for PET and Ultrasound

International Nuclear Information System (INIS)

Cucciati, G; Vara, N Di; Ghezzi, A; Paganoni, M; Pizzichemi, M; Auffray, E; Frisch, B; Lecoq, P; Bugalho, R; Neves, J; Cao, L; Peter, J; Farina, F; Felix, N; Juhan, V; Mundler, O; Siles, P; Jun, D; Lasaygues, P; Mensah, S

2014-01-01

ClearPEM-Sonic is an innovative imaging device specifically developed for breast cancer. The possibility to work in PEM-Ultrasound multimodality allows to obtain metabolic and morphological information increasing the specificity of the exam. The ClearPEM detector is developed to maximize the sensitivity and the spatial resolution as compared to Whole-Body PET scanners. It is coupled with a 3D ultrasound system, the SuperSonic Imagine Aixplorer that improves the specificity of the exam by providing a tissue elasticity map. This work describes the ClearPEM-Sonic project focusing on the technological developments it has required, the technical merits (and limits) and the first multimodal images acquired on a dedicated phantom. It finally presents selected clinical case studies that confirm the value of PEM information

Danish research and development in PEM fuel cell technology. Status for strategy follow up; Dansk forskning og udvikling inden for PEM-braendselscelleteknologi. Status for strategiopfoelgning

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-11-15

PEM fuel cell technology shows promise as to efficient and environmental friendly production of power and heat. Furthermore, the technology can be used for production of hydrogen through electrolysis of water. In Denmark research and development focus on PEM fuel cells for low temperatures (up to c 80 deg. C) as well as for high temperatures (up to 200 deg. C). This note summarizes the present plane for research and development in PEM in Denmark, including status for development within specific areas i.e. basic research and development, process development, cell and stack development and tests, and system development. (BA)

Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels (Poster)

DEFF Research Database (Denmark)

Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

One means of increasing the hydrogen yield to cost ratio of a PEM water electrolyser, is to increase the operating current density. However, at high current densities (higher than 1 A/cm2), management of heat and mass transfer in the anode current collector and channel becomes crucial and can lead...... to hot spots. Management of heat and fluid flow through the micro-channels play a great role in the capability of PEM water electrolysis when working at high current densities. Despite, many studies have been done on gas-liquid flows; still there is a lack of research on gas-liquid flows in micro......-sized channels (hydraulic diameter of 1 mm) of PEM water electrolysis. Precisely controlling all the parameters that affect the gas-liquid flow in a PEM water electrolysis cell is quite challenging, hence a simplified setup is constructed consisting of only a transparent channel with a sheet of titanium felt...

Non-platinum electrocatalysts for PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Lee, K.; Zhang, L.; Shi, Z.; Hui, R.; Zhang, J. [National Research Council of Canada, Vancouver, BC (Canada). Inst. For Fuel Cell Innovation

2008-07-01

High cost, low reliability and durability are the main barriers preventing widespread commercialization of fuel cells. In particular, the platinum (Pt)-based electrocatalysts used in proton exchange membrane (PEM) fuel cells, including direct methanol fuel cells (DMFCs) are major contributors to the high cost of PEM fuel cells. The Institute for Fuel Cell Innovation at the National Research Council of Canada has developed several new non-Pt electrocatalysts for PEM fuel cell applications. This paper presented the research results on these catalysts, including transition metal macrocycles, chalcogenides, and Ir- or Pd-based alloys. It also described catalyst structure modes via theoretical density functional theory (DFT) calculations. Research activities on these electrocatalysts was summarized in terms of catalytic activity and the oxygen reduction reaction (ORR). Typical catalysts such as cobalt(Co)-polypyrrole (PPy) and the chalcogenides show promising results in terms of catalytic activity and a 4-electron reaction mechanism. Efforts are underway to modify both catalyst structure and synthesis methods in order to further improve catalyst performance. 4 refs., 2 figs.

Device and materials modeling in PEM fuel cells

CERN Document Server

Promislow, Keith

2009-01-01

Device and Materials Modeling in PEM Fuel Cells is a specialized text that compiles the mathematical details and results of both device and materials modeling in a single volume. Proton exchange membrane (PEM) fuel cells will likely have an impact on our way of life similar to the integrated circuit. The potential applications range from the micron scale to large scale industrial production. Successful integration of PEM fuel cells into the mass market will require new materials and a deeper understanding of the balance required to maintain various operational states. This book contains articles from scientists who contribute to fuel cell models from both the materials and device perspectives. Topics such as catalyst layer performance and operation, reactor dynamics, macroscopic transport, and analytical models are covered under device modeling. Materials modeling include subjects relating to the membrane and the catalyst such as proton conduction, atomistic structural modeling, quantum molecular dynamics, an...

Energy flows modelling of a PEM electrolyzer-Photovoltaic generator-PEM fuel cell coupling dedicated to stationary applications

International Nuclear Information System (INIS)

Agbli, Krehi Serge

2012-01-01

structure (MCS) is deduced from the system EMR model. The electrical reference values of the MCS are generated by applying the power balancing method related to the inversion of the power flow exchange into the DC bus leading to the power dispatching strategy which is linked to the frequency energy management. So that, the own dynamic of each source, that is low dynamic for PEMFC and PEM electrolyzer, medium dynamic for batteries and fast dynamic for ultra-capacitors, are integrated into the energy management strategy. Different behaviour modes, depending on the state of charge of each energy storage unit, are taken into account in the power management; so that, the necessity of mixed strategies in specific behaviour has led to the coupling of energy management based fuzzy logic controller and the power balancing strategy. By applying an irradiance profile for one day, the system is simulated highlighting its suitable behaviour. Moreover, the relevance of the introduced coupling between fuzzy logic controller and the power balancing method is pointed out. (author) [fr

HOGEN{trademark} proton exchange membrane hydrogen generators: Commercialization of PEM electrolyzers

Energy Technology Data Exchange (ETDEWEB)

Smith, W.F.; Molter, T.M. [Proton Energy Systems, Inc., Rocky Hill, CT (United States)

1997-12-31

PROTON Energy Systems` new HOGEN series hydrogen generators are Proton Exchange Membrane (PEM) based water electrolyzers designed to generate 300 to 1000 Standard Cubic Feet Per Hour (SCFH) of high purity hydrogen at pressures up to 400 psi without the use of mechanical compressors. This paper will describe technology evolution leading to the HOGEN, identify system design performance parameters and describe the physical packaging and interfaces of HOGEN systems. PEM electrolyzers have served US and UK Navy and NASA needs for many years in a variety of diverse programs including oxygen generators for life support applications. In the late 1970`s these systems were advocated for bulk hydrogen generation through a series of DOE sponsored program activities. During the military buildup of the 1980`s commercial deployment of PEM hydrogen generators was de-emphasized as priority was given to new Navy and NASA PEM electrolysis systems. PROTON Energy Systems was founded in 1996 with the primary corporate mission of commercializing PEM hydrogen generators. These systems are specifically designed and priced to meet the needs of commercial markets and produced through manufacturing processes tailored to these applications. The HOGEN series generators are the first step along the path to full commercial deployment of PEM electrolyzer products for both industrial and consumer uses. The 300/1000 series are sized to meet the needs of the industrial gases market today and provide a design base that can transition to serve the needs of a decentralized hydrogen infrastructure tomorrow.

A retrospective on the LBNL PEM project

International Nuclear Information System (INIS)

Huber, J.S.; Moses, W.W.; Wang, G.C.; Derenzo, S.E.; Huesman, R.H.; Qi, J.; Virador, P.; Choong, W.S.; Mandelli, E.; Beuville, E.; Pedrali-Noy, M.; Krieger, B.; Meddeler, G.

2004-01-01

We present a retrospective on the LBNL Positron Emission Mammography (PEM) project, looking back on our design and experiences. The LBNL PEM camera utilizes detector modules that are capable of measuring depth of interaction (DOI) and places them into 4 detector banks in a rectangular geometry. In order to build this camera, we had to develop the DOI detector module, LSO etching, Lumirror-epoxy reflector for the LSO array (to achieve optimal DOI), photodiode array, custom IC, rigid-flex readout board, packaging, DOI calibration and reconstruction algorithms for the rectangular camera geometry. We will discuss the highlights (good and bad) of these developments

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.

Regenerative medicine primer.

Science.gov (United States)

Terzic, Andre; Nelson, Timothy J

2013-07-01

The pandemic of chronic diseases, compounded by the scarcity of usable donor organs, mandates radical innovation to address the growing unmet needs of individuals and populations. Beyond life-extending measures that are often the last available option, regenerative strategies offer transformative solutions in treating degenerative conditions. By leveraging newfound knowledge of the intimate processes fundamental to organogenesis and healing, the emerging regenerative armamentarium aims to boost the aptitude of human tissues for self-renewal. Regenerative technologies strive to promote, augment, and reestablish native repair processes, restituting organ structure and function. Multimodal regenerative approaches incorporate transplant of healthy tissues into damaged environments, prompt the body to enact a regenerative response in damaged tissues, and use tissue engineering to manufacture new tissue. Stem cells and their products have a unique aptitude to form specialized tissues and promote repair signaling, providing active ingredients of regenerative regimens. Concomitantly, advances in materials science and biotechnology have unlocked additional prospects for growing tissue grafts and engineering organs. Translation of regenerative principles into practice is feasible and safe in the clinical setting. Regenerative medicine and surgery are, thus, poised to transit from proof-of-principle studies toward clinical validation and, ultimately, standardization, paving the way for next-generation individualized management algorithms. Copyright © 2013 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Data acquisition electronics for positron emission mammography (PEM) detectors

International Nuclear Information System (INIS)

Martinez, J.D.; Sebastia, A.; Cerda, J.; Esteve, R.; Mora, F.J.; Toledo, J.F.; Benlloch, J.M.; Gimenez, N.; Gimenez, M.; Lerche, Ch. W.; Pavon, N.; Sanchez, F.

2005-01-01

Positron emission mammography (PEM) is an innovative technique to increase sensitivity and overcome the main drawbacks of conventional X-ray screening. However, dedicated PET imaging systems demand specific hardware solutions for data acquisition and processing that can take advantage of the reduction in the number of channels. Data acquisition issues can affect PEM scanners performance and they should be exhaustively addressed in order to exploit the increment in the event count rate. This is crucial in order to reduce both the scanning time and the total injected dose. This paper presents the electronics for our PEM camera prototype that enables us to achieve very high-count rates and perform comprehensive online processing. Results about acquisition in our detector for a typical clinical setup are studied using Monte Carlo simulation of hot lesion phantoms

Study on modulation amplitude stabilization method for PEM based on FPGA in atomic magnetometer

Science.gov (United States)

Wang, Qinghua; Quan, Wei; Duan, Lihong

2017-10-01

Atomic magnetometer which uses atoms as sensitive elements have ultra-high precision and has wide applications in scientific researches. The photoelastic modulation method based on photoelastic modulator (PEM) is used in the atomic magnetometer to detect the small optical rotation angle of a linearly polarized light. However, the modulation amplitude of the PEM will drift due to the environmental factors, which reduces the precision and long-term stability of the atomic magnetometer. Consequently, stabilizing the PEM's modulation amplitude is essential to precision measurement. In this paper, a modulation amplitude stabilization method for PEM based on Field Programmable Gate Array (FPGA) is proposed. The designed control system contains an optical setup and an electrical part. The optical setup is used to measure the PEM's modulation amplitude. The FPGA chip, with the PID control algorithm implemented in it, is used as the electrical part's micro controller. The closed loop control method based on the photoelastic modulation detection system can directly measure the PEM's modulation amplitude in real time, without increasing the additional optical devices. In addition, the operating speed of the modulation amplitude stabilization control system can be greatly improved because of the FPGA's parallel computing feature, and the PID control algorithm ensures flexibility to meet different needs of the PEM's modulation amplitude set values. The Modelsim simulation results show the correctness of the PID control algorithm, and the long-term stability of the PEM's modulation amplitude reaches 0.35% in a 3-hour continuous measurement.

Regenerative Medicine Build-Out

Science.gov (United States)

Pfenning, Michael A.; Gores, Gregory J.; Harper, C. Michel

2015-01-01

Summary Regenerative technologies strive to boost innate repair processes and restitute normative impact. Deployment of regenerative principles into practice is poised to usher in a new era in health care, driving radical innovation in patient management to address the needs of an aging population challenged by escalating chronic diseases. There is urgency to design, execute, and validate viable paradigms for translating and implementing the science of regenerative medicine into tangible health benefits that provide value to stakeholders. A regenerative medicine model of care would entail scalable production and standardized application of clinical grade biotherapies supported by comprehensive supply chain capabilities that integrate sourcing and manufacturing with care delivery. Mayo Clinic has rolled out a blueprint for discovery, translation, and application of regenerative medicine therapies for accelerated adoption into the standard of care. To establish regenerative medical and surgical service lines, the Mayo Clinic model incorporates patient access, enabling platforms and delivery. Access is coordinated through a designated portal, the Regenerative Medicine Consult Service, serving to facilitate patient/provider education, procurement of biomaterials, referral to specialty services, and/or regenerative interventions, often in clinical trials. Platforms include the Regenerative Medicine Biotrust and Good Manufacturing Practice facilities for manufacture of clinical grade products for cell-based, acellular, and/or biomaterial applications. Care delivery leverages dedicated interventional suites for provision of regenerative services. Performance is tracked using a scorecard system to inform decision making. The Mayo Clinic roadmap exemplifies an integrated organization in the discovery, development, and delivery of regenerative medicine within a growing community of practice at the core of modern health care. Significance Regenerative medicine is at the

Regenerative Medicine Build-Out.

Science.gov (United States)

Terzic, Andre; Pfenning, Michael A; Gores, Gregory J; Harper, C Michel

2015-12-01

Regenerative technologies strive to boost innate repair processes and restitute normative impact. Deployment of regenerative principles into practice is poised to usher in a new era in health care, driving radical innovation in patient management to address the needs of an aging population challenged by escalating chronic diseases. There is urgency to design, execute, and validate viable paradigms for translating and implementing the science of regenerative medicine into tangible health benefits that provide value to stakeholders. A regenerative medicine model of care would entail scalable production and standardized application of clinical grade biotherapies supported by comprehensive supply chain capabilities that integrate sourcing and manufacturing with care delivery. Mayo Clinic has rolled out a blueprint for discovery, translation, and application of regenerative medicine therapies for accelerated adoption into the standard of care. To establish regenerative medical and surgical service lines, the Mayo Clinic model incorporates patient access, enabling platforms and delivery. Access is coordinated through a designated portal, the Regenerative Medicine Consult Service, serving to facilitate patient/provider education, procurement of biomaterials, referral to specialty services, and/or regenerative interventions, often in clinical trials. Platforms include the Regenerative Medicine Biotrust and Good Manufacturing Practice facilities for manufacture of clinical grade products for cell-based, acellular, and/or biomaterial applications. Care delivery leverages dedicated interventional suites for provision of regenerative services. Performance is tracked using a scorecard system to inform decision making. The Mayo Clinic roadmap exemplifies an integrated organization in the discovery, development, and delivery of regenerative medicine within a growing community of practice at the core of modern health care. Regenerative medicine is at the vanguard of health care

PEM fuel cell modeling and simulation using Matlab

CERN Document Server

Spiegel, Colleen

2011-01-01

Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells. With this book, engineers can test components and verify designs in the development phase, saving both time and money.Easy to read and understand, this book provides design and modelling tips for

Comparison between 3D and 1D simulations of a regenerative blower for fuel cell applications

International Nuclear Information System (INIS)

Badami, M.; Mura, M.

2012-01-01

Highlights: ► A hydrogen recirculation blower for automotive fuel cells applications is studied. ► A 3D CFD analysis has been carried out to better understand the internal flows of the machine. ► The CFD results are compared to a 1D model set up by the authors in previous works. ► The main hypotheses put forward for the theoretical 1D model are compatible with the 3D analysis. - Abstract: A 3D Computational Fluid Dynamics (CFD) analysis has been carried out to better understand the internal fluid dynamics of a regenerative blower used for hydrogen recirculation in a Proton Exchange Membrane (PEM), Fuel Cell (FC) utilized for automotive applications. The obtained results are used to highlight the motion of the fluid in the vanes and in the side channel of the machine and to verify the main hypotheses put forward concerning the theoretical 1D model set up by the authors in previous works on the basis of the momentum exchange theory. Finally, the CFD analysis has been used to point out the effect of the slope of the vanes on the performance of the regenerative blower, and the results have been compared with those obtained using of the 1D model.

Simulation study of a proton exchange membrane (PEM) fuel cell system with autothermal reforming

Energy Technology Data Exchange (ETDEWEB)

Ersoz, Atilla [TUBITAK Marmara Research Centre, Energy Systems and Environmental Research Institute, 41470 Gebze, Kocaeli (Turkey); Olgun, Hayati [TUBITAK Marmara Research Centre, Energy Systems and Environmental Research Institute, 41470 Gebze, Kocaeli (Turkey); Ozdogan, Sibel [Marmara University, Faculty of Engineering, Department of Mechanical Engineering, 81040 Goztepe, Istanbul (Turkey)

2006-08-15

This paper presents the results of a study for a 100 kW net electrical power PEM fuel cell system. The major system components are an autothermal reformer, high and low temperature shift reactors, a preferential oxidation reactor, a PEM fuel cell, a combustor and an expander. Intensive heat integration within the PEM fuel cell system has been necessary to achieve acceptable net electrical efficiency levels. The calculations comprise the auxiliary equipment such as pumps, compressors, heaters, coolers, heat exchangers and pipes. The process simulation package 'ASPEN-HYSYS 3.1' has been used along with conventional calculations. The operation conditions of the autothermal reformer have been studied in detail to determine the values, which lead to the production of a hydrogen rich gas mixture with CO concentration at ppm level. The operation parameters of the other reactors have been determined considering the limitations implied by the catalysts involved. A gasoline type hydrocarbon fuel has been studied as the source for hydrogen production. The chemical composition of the hydrocarbon fuel affects the favorable operation conditions of autothermal reforming and the following fuel purification steps. Thermal efficiencies have been calculated for all of the major system components for selected operation conditions. The fuel cell stack efficiency has been calculated as a function of the number of cells (500-1250 cells). Efficiencies of all of the major system components along with auxiliary unit efficiencies determine the net electrical efficiency of the PEM fuel cell system. The obtained net electrical efficiency levels are between 30 (500 cells) and 37% (1250 cells). Hence, they are comparable with or higher than those of the conventional gasoline based internal combustion engine systems, in terms of the mechanical power efficiency.

Simulation study of a proton exchange membrane (PEM) fuel cell system with autothermal reforming

International Nuclear Information System (INIS)

Ersoz, Atilla; Olgun, Hayati; Ozdogan, Sibel

2006-01-01

This paper presents the results of a study for a 100 kW net electrical power PEM fuel cell system. The major system components are an autothermal reformer, high and low temperature shift reactors, a preferential oxidation reactor, a PEM fuel cell, a combustor and an expander. Intensive heat integration within the PEM fuel cell system has been necessary to achieve acceptable net electrical efficiency levels. The calculations comprise the auxiliary equipment such as pumps, compressors, heaters, coolers, heat exchangers and pipes. The process simulation package 'ASPEN-HYSYS 3.1' has been used along with conventional calculations. The operation conditions of the autothermal reformer have been studied in detail to determine the values, which lead to the production of a hydrogen rich gas mixture with CO concentration at ppm level. The operation parameters of the other reactors have been determined considering the limitations implied by the catalysts involved. A gasoline type hydrocarbon fuel has been studied as the source for hydrogen production. The chemical composition of the hydrocarbon fuel affects the favorable operation conditions of autothermal reforming and the following fuel purification steps. Thermal efficiencies have been calculated for all of the major system components for selected operation conditions. The fuel cell stack efficiency has been calculated as a function of the number of cells (500-1250 cells). Efficiencies of all of the major system components along with auxiliary unit efficiencies determine the net electrical efficiency of the PEM fuel cell system. The obtained net electrical efficiency levels are between 30 (500 cells) and 37% (1250 cells). Hence, they are comparable with or higher than those of the conventional gasoline based internal combustion engine systems, in terms of the mechanical power efficiency

Regenerative medicine blueprint.

Science.gov (United States)

Terzic, Andre; Harper, C Michel; Gores, Gregory J; Pfenning, Michael A

2013-12-01

Regenerative medicine, a paragon of future healthcare, holds unprecedented potential in extending the reach of treatment modalities for individuals across diseases and lifespan. Emerging regenerative technologies, focused on structural repair and functional restoration, signal a radical transformation in medical and surgical practice. Regenerative medicine is poised to provide innovative solutions in addressing major unmet needs for patients, ranging from congenital disease and trauma to degenerative conditions. Realization of the regenerative model of care predicates a stringent interdisciplinary paradigm that will drive validated science into standardized clinical options. Designed as a catalyst in advancing rigorous new knowledge on disease causes and cures into informed delivery of quality care, the Mayo Clinic regenerative medicine blueprint offers a patient-centered, team-based strategy that optimizes the discovery-translation-application roadmap for the express purpose of science-supported practice advancement.

Solar Airplanes and Regenerative Fuel Cells

Science.gov (United States)

Bents, David J.

2007-01-01

A solar electric aircraft with the potential to "fly forever" has captured NASA's interest, and the concept for such an aircraft was pursued under Aeronautics Environmental Research Aircraft and Sensor Technology (ERAST) project. Feasibility of this aircraft happens to depend on the successful development of solar power technologies critical to NASA's Exploration Initiatives; hence, there was widespread interest throughout NASA to bring these technologies to a flight demonstration. The most critical is an energy storage system to sustain mission power during night periods. For the solar airplane, whose flight capability is already limited by the diffuse nature of solar flux and subject to latitude and time of year constraints, the feasibility of long endurance flight depends on a storage density figure of merit better than 400-600 watt-hr per kilogram. This figure of merit is beyond the capability of present day storage technologies (other than nuclear) but may be achievable in the hydrogen-oxygen regenerative fuel cell (RFC). This potential has led NASA to undertake the practical development of a hydrogen-oxygen regenerative fuel cell, initially as solar energy storage for a high altitude UAV science platform but eventually to serve as the primary power source for NASAs lunar base and other planet surface installations. Potentially the highest storage capacity and lowest weight of any non-nuclear device, a flight-weight RFC aboard a solar-electric aircraft that is flown continuously through several successive day-night cycles will provide the most convincing demonstration that this technology's widespread potential has been realized. In 1998 NASA began development of a closed cycle hydrogen oxygen PEM RFC under the Aeronautics Environmental Research Aircraft and Sensor Technology (ERAST) project and continued its development, originally for a solar electric airplane flight, through FY2005 under the Low Emissions Alternative Power (LEAP) project. Construction of

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)

UARS PEM Level 2 MEPS V001

Data.gov (United States)

National Aeronautics and Space Administration — The Particle Environment Monitor (PEM) level 2 Medium-Energy Particle Spectrometer (MEPS) daily product contains the electron and proton high-resolution spectral...

Structured modelling and nonlinear analysis of PEM fuel cells; Strukturierte Modellierung und nichtlineare Analyse von PEM-Brennstoffzellen

Energy Technology Data Exchange (ETDEWEB)

Hanke-Rauschenbach, R.

2007-10-26

In the first part of this work a model structuring concept for electrochemical systems is presented. The application of such a concept for the structuring of a process model allows it to combine different fuel cell models to form a whole model family, regardless of their level of detail. Beyond this the concept offers the opportunity to flexibly exchange model entities on different model levels. The second part of the work deals with the nonlinear behaviour of PEM fuel cells. With the help of a simple, spatially lumped and isothermal model, bistable current-voltage characteristics of PEM fuel cells operated with low humidified feed gases are predicted and discussed in detail. The cell is found to exhibit current-voltage curves with pronounced local extrema in a parameter range that is of practical interest when operated at constant feed gas flow rates. (orig.)

A New Control and Design of PEM Fuel Cell System Powered Diffused Air Aeration System

Directory of Open Access Journals (Sweden)

Hassen T. Dorrah

2012-06-01

Full Text Available The goal of aquaculture ponds is to maximize production and profits while holding labor and management efforts to the minimum. Poor water quality in most ponds causes risk of fish kills, disease outbreaks which lead to minimization of pond production. Dissolved Oxygen (DO is considered to be among the most important water quality parameters in fish culture. Fish ponds in aquaculture farms are usually located in remote areas where grid lines are at far distance. Aeration of ponds is required to prevent mortality and to intensify production, especially when feeding is practical, and in warm regions. To increase pond production it is necessary to control dissolved oxygen. Aeration offers the most immediate and practical solution to water quality problems encountered at higher stocking and feeding rates. Many units of aeration system are electrical units so using a continuous, high reliability, affordable, and environmentally friendly power sources is necessary. Fuel cells have become one of the major areas of research in the academia and the industry. Aeration of water by using PEM fuel cell power is not only a new application of the renewable energy, but also, it provides an affordable method to promote biodiversity in stagnant ponds and lakes. This paper presents a new design and control of PEM fuel cell powered a diffused air aeration system for a shrimp farm in Mersa Matruh in Egypt. Also Artificial intelligence (AI control techniques are used to control the fuel cell output power by controlling its input gases flow rate. Moreover the mathematical modeling and simulation of PEM fuel cell is introduced. A comparative study is applied between the performance of fuzzy logic controller (FLC and neural network controller (NNC. The results show the effectiveness of NNC over FLC.

Use of elastomers in regenerative braking systems

Science.gov (United States)

The storage of potential energy as strain energy in elastomers was investigated. The evolution of the preferred stressing scheme is described, and test results on full-size elastomeric energy storage units sized for an automotive regenerative braking system application are presented. The need for elastomeric material improvements is also discussed.

Quantify and improve PEM fuel cell durability. Final report

Energy Technology Data Exchange (ETDEWEB)

Grahl-Madsen, L.; Odgaard, M.; Munksgaard Nielsen, R. (IRD Fuel Cell A/S, Svendborg (Denmark)); Li, Q.; Jensen, Jens Oluf (Technical Univ. of Denmark, Dept. of Chemistry, Kgs. Lyngby (Denmark)); Andersen, Shuang Ma; Speder, J.; Skou, E. (Syddansk Univ. (SDU), Odense (Denmark))

2010-07-01

The aim of the present project is to systematically quantify and improve the durability of the PEM FC including the following three PEM FC variants: LT PEM FC, DMFC, and HT PEM FC. Different factors influencing dissolution properties of noble metal catalyst platinum and platinum-ruthenium alloy has been studied. The dissolution was found to increase by increasing the CV cycle upper potential limit, number of potential cycles, solution acidity, oxygen partial pressure, involvement of chloride, and temperature. Ruthenium was found to deteriorate ten (10) times faster than platinum catalyst; and carbon supported catalyst (Pt: 20%, Ru: up to 100%) deteriorate ten (10) times faster than non-supported catalyst (Pt: 2%, Ru: 30%) at the same condition. Loss of sulphonic acid groups and fluoride from perfluorinated sulfonic acid membrane was confirmed by different techniques, which locally leads to loss of acidity, and consequently enhances dissolution of noble metal catalyst. Degradation of Nafion ionomer in the electrode was enhanced by noble metal catalyst and the thermal decomposition properties has synergetic effect with carbon degradation. Hydrophobicity of GDL and electrode on GDL were found to degrade e.g. radical attack, oxidation, and physical wear out. The very top micro surface structure turned out to be responsible for wetting property after chemical ageing. Optimal catalyst and ionomer ratio is also reflected in contact angle value, which can be understood in terms of catalyst/carbon - ionomer affinity and layered structure. Long-term tested and 'virgin' LT PEM MEAs have been characterised with respect to SEM, TEM, EDS, and XRD. Both failed and well-functioning MEAs have been characterised. The Post Mortem analysis has shown and quantified degradation mechanisms like catalyst growth and carbon corrosion. Furthermore, the effect of fuel starvation was shown by pronounced Ru-catalyst band within the membrane. The catalyst coarsening observed after

A novel analytical analysis of PEM fuel cell

International Nuclear Information System (INIS)

Yazdi, Mohamad Zardoshtizade; Kalbasi, Mansour

2010-01-01

In this study, a quasi three-dimensional model was developed for a single proton exchange membrane (PEM) fuel cell. The model was used for a half-cell which includes the cathode gas channel, gas diffusion layer (GDL), cathode catalyst layer and membrane is modeled. This model includes mass transfer in the gas channel and GDL, electrochemistry reaction in cathode catalyst layer, and charge transfer in the membrane phase. These expressions were solved by analytical methods. An agglomerate approach was used to describe cathode catalyst layer. By using analytical solution, the expressions can predict the PEM fuel cell behavior in different conditions which is the advantage of this method.

Investigation of low glass transition temperature on COTS PEM's reliability for space applications

Science.gov (United States)

Sandor, M.; Agarwal, S.; Peters, D.; Cooper, M. S.

2003-01-01

Plastic Encapsulated Microelectronics (PEM) reliability is affected by many factors. Glass transition temperature (Tg) is one such factor. In this presentation issues relating to PEM reliability and the effect of low glass transition temperature epoxy mold compounds are presented.

Reforming options for hydrogen production from fossil fuels for PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Ersoz, Atilla; Olgun, Hayati [TUBITAK Marmara Research Center, Institute of Energy, Gebze, 41470 Kocaeli (Turkey); Ozdogan, Sibel [Marmara University Faculty of Engineering, Goztepe, 81040 Istanbul (Turkey)

2006-03-09

PEM fuel cell systems are considered as a sustainable option for the future transport sector in the future. There is great interest in converting current hydrocarbon based transportation fuels into hydrogen rich gases acceptable by PEM fuel cells on-board of vehicles. In this paper, we compare the results of our simulation studies for 100kW PEM fuel cell systems utilizing three different major reforming technologies, namely steam reforming (SREF), partial oxidation (POX) and autothermal reforming (ATR). Natural gas, gasoline and diesel are the selected hydrocarbon fuels. It is desired to investigate the effect of the selected fuel reforming options on the overall fuel cell system efficiency, which depends on the fuel processing, PEM fuel cell and auxiliary system efficiencies. The Aspen-HYSYS 3.1 code has been used for simulation purposes. Process parameters of fuel preparation steps have been determined considering the limitations set by the catalysts and hydrocarbons involved. Results indicate that fuel properties, fuel processing system and its operation parameters, and PEM fuel cell characteristics all affect the overall system efficiencies. Steam reforming appears as the most efficient fuel preparation option for all investigated fuels. Natural gas with steam reforming shows the highest fuel cell system efficiency. Good heat integration within the fuel cell system is absolutely necessary to achieve acceptable overall system efficiencies. (author)

Reforming options for hydrogen production from fossil fuels for PEM fuel cells

Science.gov (United States)

Ersoz, Atilla; Olgun, Hayati; Ozdogan, Sibel

PEM fuel cell systems are considered as a sustainable option for the future transport sector in the future. There is great interest in converting current hydrocarbon based transportation fuels into hydrogen rich gases acceptable by PEM fuel cells on-board of vehicles. In this paper, we compare the results of our simulation studies for 100 kW PEM fuel cell systems utilizing three different major reforming technologies, namely steam reforming (SREF), partial oxidation (POX) and autothermal reforming (ATR). Natural gas, gasoline and diesel are the selected hydrocarbon fuels. It is desired to investigate the effect of the selected fuel reforming options on the overall fuel cell system efficiency, which depends on the fuel processing, PEM fuel cell and auxiliary system efficiencies. The Aspen-HYSYS 3.1 code has been used for simulation purposes. Process parameters of fuel preparation steps have been determined considering the limitations set by the catalysts and hydrocarbons involved. Results indicate that fuel properties, fuel processing system and its operation parameters, and PEM fuel cell characteristics all affect the overall system efficiencies. Steam reforming appears as the most efficient fuel preparation option for all investigated fuels. Natural gas with steam reforming shows the highest fuel cell system efficiency. Good heat integration within the fuel cell system is absolutely necessary to achieve acceptable overall system efficiencies.

Plastic Encapsulated Microcircuits (PEMs) Reliability Guide

Science.gov (United States)

Sandor, M.

2000-01-01

It is reported by some users and has been demonstrated by others via testing and qualification that the quality and reliability of plastic-encapsulated microcircuits (PEMs) manufactured today are excellent in commercial applications and closely equivalent, and in some cases superior to their hemetic counterparts.

Laser Ablation Increases PEM/Catalyst Interfacial Area

Science.gov (United States)

Whitacre, Jay; Yalisove, Steve

2009-01-01

An investigational method of improving the performance of a fuel cell that contains a polymer-electrolyte membrane (PEM) is based on the concept of roughening the surface of the PEM, prior to deposition of a thin layer of catalyst, in order to increase the PEM/catalyst interfacial area and thereby increase the degree of utilization of the catalyst. The roughening is done by means of laser ablation under carefully controlled conditions. Next, the roughened membrane surface is coated with the thin layer of catalyst (which is typically platinum), then sandwiched between two electrode/catalyst structures to form a membrane/ele c t - rode assembly. The feasibility of the roughening technique was demonstrated in experiments in which proton-conducting membranes made of a perfluorosulfonic acid-based hydrophilic, protonconducting polymer were ablated by use of femtosecond laser pulses. It was found that when proper combinations of the pulse intensity, pulse-repetition rate, and number of repetitions was chosen, the initially flat, smooth membrane surfaces became roughened to such an extent as to be converted to networks of nodules interconnected by filaments (see Figure 1). In further experiments, electrochemical impedance spectroscopy (EIS) was performed on a pristine (smooth) membrane and on two laser-roughened membranes after the membranes were coated with platinum on both sides. Some preliminary EIS data were interpreted as showing that notwithstanding the potential for laser-induced damage, the bulk conductivities of the membranes were not diminished in the roughening process. Other preliminary EIS data (see Figure 2) were interpreted as signifying that the surface areas of the laser-roughened membranes were significantly greater than those of the smooth membrane. Moreover, elemental analyses showed that the sulfur-containing molecular groups necessary for proton conduction remained intact, even near the laser-roughened surfaces. These preliminary results can be taken

Development of coincidence processing module for PEM

International Nuclear Information System (INIS)

Feng Baotong; Shuai Lei; Li Ke

2011-01-01

For the breast cancer diagnosis and therapy, a prototype of positron emission mammography (PEM) was developed in Institute of High Energy Physics, Chinese Academy of Sciences. In this paper, the design of coincidence processing module (CPM) for this PEM was presented. Both the hardware architecture and the software logic were introduced. In this design, the CPM used the Rocket IO fast interface in FPGA and fiber technology to acquire the preprocessed data from the continuous sampling module (CSM) and then selected the valid event with the coincidence timing window method, which was performed in the FPGA on the daughter board. The CPM transmits the processed data to host computer via gigabit Ethernet. The whole system was controlled by CAN bus. The primary tests indicate that the performance of this design is good. (authors)

A Frequency-Domain Adaptive Filter (FDAF) Prediction Error Method (PEM) Framework for Double-Talk-Robust Acoustic Echo Cancellation

DEFF Research Database (Denmark)

Gil-Cacho, Jose M.; van Waterschoot, Toon; Moonen, Marc

2014-01-01

to the FDAF-PEM-AFROW algorithm. We show that FDAF-PEM-AFROW is by construction related to the best linear unbiased estimate (BLUE) of the echo path. We depart from this framework to show an improvement in performance with respect to other adaptive filters minimizing the BLUE criterion, namely the PEM......In this paper, we propose a new framework to tackle the double-talk (DT) problem in acoustic echo cancellation (AEC). It is based on a frequency-domain adaptive filter (FDAF) implementation of the so-called prediction error method adaptive filtering using row operations (PEM-AFROW) leading...... regularization (VR) algorithms. The FDAF-PEM-AFROW versions significantly outperform the original versions in every simulation. In terms of computational complexity, the FDAF-PEM-AFROW versions are themselves about two orders of magnitude cheaper than the original versions....

PEM fuel cell cost minimization using ``Design For Manufacture and Assembly`` techniques

Energy Technology Data Exchange (ETDEWEB)

Lomax, F.D. Jr.; James, B.D. [Directed Technologies, Inc., Arlington, VA (United States); Mooradian, R.P. [Ford Motor Co., Dearborn, MI (United States)

1997-12-31

Polymer Electrolyte Membrane (PEM) fuel cells fueled with direct hydrogen have demonstrated substantial technical potential to replace Internal Combustion Engines (ICE`s) in light duty vehicles. Such a transition to a hydrogen economy offers the potential of substantial benefits from reduced criteria and greenhouse emissions as well as reduced foreign fuel dependence. Research conducted for the Ford Motor Co. under a US Department of Energy contract suggests that hydrogen fuel, when used in a fuel cell vehicle (FCV), can achieve a cost per vehicle mile less than or equal to the gasoline cost per mile when used in an ICE vehicle. However, fuel cost parity is not sufficient to ensure overall economic success: the PEM fuel cell power system itself must be of comparable cost to the ICE. To ascertain if low cost production of PEM fuel cells is feasible, a powerful set of mechanical engineering tools collectively referred to as Design for Manufacture and Assembly (DFMA) has been applied to several representative PEM fuel cell designs. The preliminary results of this work are encouraging, as presented.

A multi-phase, multi-component PEM fuel cell model. Paper no. IGEC-1-051

International Nuclear Information System (INIS)

Baschuk, J.J.; Li, X.

2005-01-01

'Full text:' Mathematical modeling is an important tool for PEM fuel cell commercialization. Mathematical models can illustrate the effect of the different processes on the overall performance of a PEM fuel cell; thus, mathematical models can be used to as a design tool to find optimal designs and operating conditions. A general formulation for a comprehensive fuel cell model, based on the conservation principle and volume-averaging, is presented. The model formulation includes the electro-chemical reactions, proton migration, and the mass transport of the gaseous reactants and liquid water. Additionally, the model formulation can be applied to all regions of the PEM fuel cell: the bipolar plates, gas flow channels, electrode backing, catalyst, and polymer electrolyte layers. Numerical results, showing the effect of water flooding on PEM fuel cell performance, are presented. (author)

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.

Production of hydrogen using composite membrane in PEM water electrolysis

Energy Technology Data Exchange (ETDEWEB)

Santhi priya, E.L.; Mahender, C.; Mahesh, Naga; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad-500 085, A.P (India); Anjaneyulu, Y. [Director, TLGVRC, JSU Box 18739, JSU, Jackson, MS 32917-0939 (United States)

2012-07-01

Electrolysis of water is the best known technology till today to produce hydrogen. The only practical way to produce hydrogen using renewable energy sources is by proton exchange membrane (PEM) water electrolysis. The most commonly used PEM membrane is Nafion. Composite membrane of TiO2 is synthesized by casting method using Nafion 5wt% solution. RuO2 is used as anode and 10 wt% Pd on activated carbon is used as cathode in the water electrolyser system. The performance of this Composite membrane is studied by varying voltage range 1.8 to 2.6V with respect to hydrogen yield and at current density 0.1, 0.2, 0.3, 0.4, and 0.5(A cm-2). This Composite membrane has been tested using in-house fabricated single cell PEM water electrolysis cell with 10cm2 active area at temperatures ranging from 30,45,65 850c and at 1 atmosphere pressure.

Compendium of NASA data base for the global tropospheric experiment's Pacific Exploratory Mission West-B (PEM West-B)

Science.gov (United States)

Gregory, Gerald L.; Scott, A. Donald, Jr.

1995-01-01

This compendium describes aircraft data that are available from NASA's Pacific Exploratory Mission West-B (PEM West-B). PEM West is a component of the International Global Atmospheric Chemistry's (IGAC) East Asia/North Pacific Regional Study (APARE) project. Objectives of PEM West are to investigate the atmospheric chemistry of ozone over the northwest Pacific -- natural budgets and the impact of anthropogenic/continental sources; and to investigate sulfur chemistry -- continental and marine sulfur sources. The PEM West program encompassed two expeditions. PEM West-A was conducted in September 1991 during which the predominance of tropospheric air was from mid-Pacific (marine) regions, but (at times) was modified by Asian outflow. PEM West-B was conducted during February 1994, a period characterized by maximum Asian outflow. Results from PEM West-A and B are public domain. PEM West-A data are summarized in NASA TM 109177 (published February 1995). Flight experiments were based at Guam, Hong Kong, and Japan. This document provides a representation of NASA DC-8 aircraft data that are available from NASA Langley's Distributed Active Archive Center (DAAC). The DAAC includes numerous other data such as meteorological and modeling products, results from surface studies, satellite observations, and sonde releases.

Compendium of NASA data base for the Global Tropospheric Experiment's Pacific Exploratory Mission West-A (PEM West-A)

Science.gov (United States)

Gregory, G. L.; Scott, A. D., Jr.

1995-01-01

This compendium describes aircraft data that are available from NASA's Pacific Exploratory Mission West-A (PEM West-A). PEM West is a component of the International Global Atmospheric Chemistry's (IGAC) East Asia/North Pacific Regional Study (APARE) project. The PEM- West program encompassed two expeditions to study contrasting meteorological regimes in the Pacific. Objectives of PEM West are to investigate the atmospheric chemistry of ozone over the northwest Pacific -- natural budgets and the impact of anthropogenic sources; and to investigate sulfur chemistry -- continental versus marine sulfur sources. PEM West-A was conducted in September 1991 during which the predominance of tropospheric air is from the mid-Pacific (marine) regions, but (at times) is modified/mixed with Asian continental outflow. PEM West-B was conducted during February 1994, a period characterized by maximum continental outflow. PEM-B data (not included) will become public domain during the Summer of 1995. PEM West-A flight experiments were based at Japan, Hong Kong, and Guam. This document provides a representation of NASA DC-8 aircraft data that are available from NASA Langley's Distributed Active Archive Center (DAAC), which include numerous data such as meteorological observations, modeling products, results from surface studies, satellite observations, and sonde releases.

High temperature PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jianlu; Xie, Zhong; Zhang, Jiujun; Tang, Yanghua; Song, Chaojie; Navessin, Titichai; Shi, Zhiqing; Song, Datong; Wang, Haijiang; Wilkinson, David P.; Liu, Zhong-Sheng; Holdcroft, Steven [Institute for Fuel Cell Innovation, National Research Council Canada, Vancouver, BC (Canada V6T 1W5)

2006-10-06

There are several compelling technological and commercial reasons for operating H{sub 2}/air PEM fuel cells at temperatures above 100{sup o}C. Rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. This review paper provides a concise review of high temperature PEM fuel cells (HT-PEMFCs) from the perspective of HT-specific materials, designs, and testing/diagnostics. The review describes the motivation for HT-PEMFC development, the technology gaps, and recent advances. HT-membrane development accounts for {approx}90% of the published research in the field of HT-PEMFCs. Despite this, the status of membrane development for high temperature/low humidity operation is less than satisfactory. A weakness in the development of HT-PEMFC technology is the deficiency in HT-specific fuel cell architectures, test station designs, and testing protocols, and an understanding of the underlying fundamental principles behind these areas. The development of HT-specific PEMFC designs is of key importance that may help mitigate issues of membrane dehydration and MEA degradation. (author)

DOD Residential Proton Exchange Membrane (PEM) Fuel Cell Demonstration Program. Volume 2. Summary of Fiscal Year 2001-2003 Projects

Science.gov (United States)

2005-09-01

produced many of the Beatles 1970s recordings. This facility was selected to host the UK PEM demonstration project from a selection of four potential sites...funded the Department of Defense (DOD) Residential PEM Demonstration Project to demonstrate domestically-produced, residential Proton Exchange Membrane...PEM) fuel cells at DOD Facilities. The objectives were to: (1) assess PEM fuel cells’ role in supporting sustainability at military installations

Effect of compressive force on PEM fuel cell performance

Science.gov (United States)

MacDonald, Colin Stephen

Polymer electrolyte membrane (PEM) fuel cells possess the potential, as a zero-emission power source, to replace the internal combustion engine as the primary option for transportation applications. Though there are a number of obstacles to vast PEM fuel cell commercialization, such as high cost and limited durability, there has been significant progress in the field to achieve this goal. Experimental testing and analysis of fuel cell performance has been an important tool in this advancement. Experimental studies of the PEM fuel cell not only identify unfiltered performance response to manipulation of variables, but also aid in the advancement of fuel cell modelling, by allowing for validation of computational schemes. Compressive force used to contain a fuel cell assembly can play a significant role in how effectively the cell functions, the most obvious example being to ensure proper sealing within the cell. Compression can have a considerable impact on cell performance beyond the sealing aspects. The force can manipulate the ability to deliver reactants and the electrochemical functions of the cell, by altering the layers in the cell susceptible to this force. For these reasons an experimental study was undertaken, presented in this thesis, with specific focus placed on cell compression; in order to study its effect on reactant flow fields and performance response. The goal of the thesis was to develop a consistent and accurate general test procedure for the experimental analysis of a PEM fuel cell in order to analyse the effects of compression on performance. The factors potentially affecting cell performance, which were a function of compression, were identified as: (1) Sealing and surface contact; (2) Pressure drop across the flow channel; (3) Porosity of the GDL. Each factor was analysed independently in order to determine the individual contribution to changes in performance. An optimal degree of compression was identified for the cell configuration in

Regenerative endodontics.

Science.gov (United States)

Simon, S; Smith, A J

2014-03-01

Significant advances in our understanding of the biological processes involved in tooth development and repair at the cellular and molecular levels have underpinned the newly emerging area of regenerative endodontics. Development of treatment protocols based on exploiting the natural wound healing properties of the dental pulp and applying tissue engineering principles has allowed reporting of case series showing preservation of tissue vitality and apexogenesis. To review current case series reporting regenerative endodontics. Current treatment approaches tend to stimulate more reparative than regenerative responses in respect of the new tissue generated, which often does not closely resemble the physiological structure of dentine-pulp. However, despite these biological limitations, such techniques appear to offer significant promise for improved treatment outcomes. Improved biological outcomes will likely emerge from the many experimental studies being reported and will further contribute to improvements in clinical treatment protocols.

Commercialization of proton exchange membrane (PEM) fuel cell technology

International Nuclear Information System (INIS)

Goel, N.; Pant, A.; Sera, G.

1995-01-01

The MCTTC performed a market assessment for PEM Fuel Cells for terrestrial applications for the Center for Space Power (CSP). The purpose of the market assessment was to gauge the market and commercial potential for PEM fuel cell technology. Further, the market assessment was divided into subsections of technical and market overview, competitive environment, political environment, barriers to market entry, and keys to market entry. The market assessment conducted by the MCTTC involved both secondary and primary research. The primary target markets for PEM fuel cells were transportation and utilities in the power range of 10 kW to 100 kW. The fuel cell vehicle market size was estimated under a pessimistic scenario and an optimistic scenario. The estimated size of the fuel cell vehicle market in dollar terms for the year 2005 is $17.3 billion for the pessimistic scenario and $34.7 billion for the optimistic scenario. The fundamental and applied research funded and conducted by the National Aeronautics and Space Administration (NASA) and DOE in the area of fuel cells presents an excellent opportunity to commercialize dual-use technology and enhance U.S. business competitiveness. copyright 1995 American Institute of Physics

Researches on regenerative medicine-current state

Directory of Open Access Journals (Sweden)

WANG Zheng-guo

2012-11-01

Full Text Available 【Abstract】 Since 1980s, the rapid development of tissue engineering and stem cell research has pushed re-generative medicine to a new fastigium, and regenerative medicine has become a noticeable research field in the international biology and medicine. In China, about 100 million patients need repair and regeneration treatment every year, while the number is much larger in the world. Regenerative medicine could provide effective salvation for these patients. Both Chinese Academy of Sciences and Chinese Academy of Engineering have made roadmaps of 2010-2050 and 2011-2030 for regenerative medicine. The final goal of the two roadmaps is to make China go up to leading position in most research aspects of regenerative medicine. In accord with this strategy, the government and some enterprises have invested 3-5 billion RMB (0.5-0.8 billion USD for the research on regenerative medicine. In order to push the translation of regenerative medicine forward—from bench to bedside, a strategic alliance has been established, and it includes 27 top-level research institutes, medical institutes, colleges, universities and enterprises in the field of stem cell and regeneration medicine. Recently the journal, Science, has published a special issue—Regenerative Medi-cine in China, consisting of 35 papers dealing with stem cell and regeneration, tissue engineering and regeneration, trauma and regeneration and bases for tissue repair and regenerative medicine. It is predicated that a greater breakthrough in theory and practice of regenerative medicine will be achieved in the near future (20 to 30 years. Key words: Regenerative medicine; Tissue engineering; Stem cells; Wound healing

Framework for the assessment of PEMS (Portable Emissions Measurement Systems) uncertainty.

Science.gov (United States)

Giechaskiel, Barouch; Clairotte, Michael; Valverde-Morales, Victor; Bonnel, Pierre; Kregar, Zlatko; Franco, Vicente; Dilara, Panagiota

2018-06-13

European regulation 2016/427 (the first package of the so-called Real-Driving Emissions (RDE) regulation) introduced on-road testing with Portable Emissions Measurement Systems (PEMS) to complement the chassis dynamometer laboratory (Type I) test for the type approval of light-duty vehicles in the European Union since September 2017. The Not-To-Exceed (NTE) limit for a pollutant is the Type I test limit multiplied by a conformity factor that includes a margin for the additional measurement uncertainty of PEMS relative to standard laboratory equipment. The variability of measured results related to RDE trip design, vehicle operating conditions, and data evaluation remain outside of the uncertainty margin. The margins have to be reviewed annually (recital 10 of regulation 2016/646). This paper lays out the framework used for the first review of the NO x margin, which is also applicable to future margin reviews. Based on experimental data received from the stakeholders of the RDE technical working group in 2017, two NO x margin scenarios of 0.24-0.43 were calculated, accounting for different assumptions of possible zero drift behaviour of the PEMS during the tests. The reduced uncertainty margin compared to the one foreseen for 2020 (0.5) reflects the technical improvement of PEMS over the past few years. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

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...

Salt Effects on Surface Structures of Polyelectrolyte Multilayers (PEMs) Investigated by Vibrational Sum Frequency Generation (SFG) Spectroscopy.

Science.gov (United States)

Ge, Aimin; Matsusaki, Michiya; Qiao, Lin; Akashi, Mitsuru; Ye, Shen

2016-04-26

Sum frequency generation (SFG) vibrational spectroscopy was employed to investigate the surface structures of polyelectrolyte multilayers (PEMs) constructed by sequentially alternating adsorption of poly(diallyldimethylammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS). It was found that the surface structures and surface charge density of the as-deposited PEMs of PDDA/PSS significantly depend on the concentration of sodium chloride (NaCl) present in the polyelectrolyte solutions. Furthermore, it was found that the surface structure of the as-deposited PEMs is in a metastable state and will reach the equilibrium state by diffusion of the polyelectrolyte chain after an aging process, resulting in a polyelectrolyte mixture on the PEM surfaces.

Water droplet accumulation and motion in PEM (Proton Exchange Membrane) fuel cell mini-channels

International Nuclear Information System (INIS)

Carton, J.G.; Lawlor, V.; Olabi, A.G.; Hochenauer, C.; Zauner, G.

2012-01-01

Effective water management is one of the key strategies for improving low temperature PEM (Proton Exchange Membrane) fuel cell performance and durability. Phenomena such as membrane dehydration, catalyst layer flooding, mass transport and fluid flow regimes can be affected by the interaction, distribution and movement of water in flow plate channels. In this paper a literature review is completed in relation to PEM fuel cell water flooding. It is clear that droplet formation, movement and interaction with the GDL (Gas Diffusion Layer) have been studied extensively. However slug formation and droplet accumulation in the flow channels has not been analysed in detail. In this study, a CFD (Computational Fluid Dynamic) model and VOF (Volume of Fluid) method is used to simulate water droplet movement and slug formation in PEM fuel cell mini-channels. In addition, water slug visualisation is recorded in ex situ PEM fuel cell mini-channels. Observation and simulation results are discussed with relation to slug formation and the implications to PEM fuel cell performance. -- Highlights: ► Excess water in mini-channels from the collision and coalescence of droplets can directly form slugs in PEM fuel cells. ► Slugs can form at low flow rates so increasing the flow rate can reduce the size and frequency of slugs. ► One channel of a double serpentine mini-channel may become blocked due to the redistribution of airflow and pressure caused by slug formation. ► Correct GDL and mini-channel surface coatings are essential to reduce slug formation and stagnation. ► Having geometry changes (bends and steps) in the flow fields can disrupt slug movement and avoid channel blockages.

Fuel starvation. Irreversible degradation mechanisms in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Rangel, Carmen M.; Silva, R.A.; Travassos, M.A.; Paiva, T.I.; Fernandes, V.R. [LNEG, National Laboratory for Energy and Geology, Lisboa (Portugal). UPCH Fuel Cells and Hydrogen Unit

2010-07-01

PEM fuel cell operates under very aggressive conditions in both anode and cathode. Failure modes and mechanism in PEM fuel cells include those related to thermal, chemical or mechanical issues that may constrain stability, power and lifetime. In this work, the case of fuel starvation is examined. The anode potential may rise to levels compatible with the oxidization of water. If water is not available, oxidation of the carbon support will accelerate catalyst sintering. Diagnostics methods used for in-situ and ex-situ analysis of PEM fuel cells are selected in order to better categorize irreversible changes of the cell. Electrochemical Impedance Spectroscopy (EIS) is found instrumental in the identification of fuel cell flooding conditions and membrane dehydration associated to mass transport limitations / reactant starvation and protonic conductivity decrease, respectively. Furthermore, it indicates that water electrolysis might happen at the anode. Cross sections of the membrane catalyst and gas diffusion layers examined by scanning electron microscopy indicate electrode thickness reduction as a result of reactions taking place during hydrogen starvation. Catalyst particles are found to migrate outwards and located on carbon backings. Membrane degradation in fuel cell environment is analyzed in terms of the mechanism for fluoride release which is considered an early predictor of membrane degradation. (orig.)

Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging

Energy Technology Data Exchange (ETDEWEB)

Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

2001-06-01

Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom.

Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging

International Nuclear Information System (INIS)

Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

2001-01-01

Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom

Regenerative similariton laser

Directory of Open Access Journals (Sweden)

Thibault North

2016-05-01

Full Text Available Self-pulsating lasers based on cascaded reshaping and reamplification (2R are capable of initiating ultrashort pulses despite the accumulation of large amounts of nonlinearities in all-fiber resonators. The spectral properties of pulses in self-similar propagation are compatible with cascaded 2R regeneration by offset filtering, making parabolic pulses suitable for the design of a laser of this recently introduced class. A new type of regenerative laser giving birth to similaritons is numerically investigated and shows that this laser is the analog of regenerative sources based solely on self-phase modulation and offset filtering. The regenerative similariton laser does not suffer from instabilities due to excessive nonlinearities and enables ultrashort pulse generation in a simple cavity configuration.

Regenerative rehabilitation: a new future?

Science.gov (United States)

Perez-Terzic, Carmen; Childers, Martin K

2014-11-01

Modern rehabilitation medicine is propelled by newfound knowledge aimed at offering solutions for an increasingly aging population afflicted by chronic debilitating conditions. Considered a core component of future health care, the rollout of regenerative medicine underscores a paradigm shift in patient management targeted at restoring physiologic function and restituting normative impact. Nascent regenerative technologies offer unprecedented prospects in achieving repair of degenerated, diseased, or damaged tissues. In this context, principles of regenerative science are increasingly integrated in rehabilitation practices as illustrated in the present Supplement. Encompassing a growing multidisciplinary domain, the emergent era of "regenerative rehabilitation" brings radical innovations at the forefront of healthcare blueprints.

Bipolar Plates for PEM Systems

OpenAIRE

Lædre, Sigrid

2016-01-01

Summary of thesis: The Bipolar Plate (BPP) is an important component in both Proton Exchange Membrane Fuel Cells (PEMFCs) and Proton Exchange Membrane Water Electrolyzers (PEMWEs). Bipolar plate material and processing constitutes for a large fraction of the cost and weight of a PEM cell stack. The main tasks for the bipolar plates in both systems are to separate single cell in a stack, conduct current between single cells and remove heat from active areas. In addition, the BPPs distribu...

A comprehensive, consistent and systematic mathematical model of PEM fuel cells

International Nuclear Information System (INIS)

Baschuk, J.J.; Li Xianguo

2009-01-01

This paper presents a comprehensive, consistent and systematic mathematical model for PEM fuel cells that can be used as the general formulation for the simulation and analysis of PEM fuel cells. As an illustration, the model is applied to an isothermal, steady state, two-dimensional PEM fuel cell. Water is assumed to be in either the gas phase or as a liquid phase in the pores of the polymer electrolyte. The model includes the transport of gas in the gas flow channels, electrode backing and catalyst layers; the transport of water and hydronium in the polymer electrolyte of the catalyst and polymer electrolyte layers; and the transport of electrical current in the solid phase. Water and ion transport in the polymer electrolyte was modeled using the generalized Stefan-Maxwell equations, based on non-equilibrium thermodynamics. Model simulations show that the bulk, convective gas velocity facilitates hydrogen transport from the gas flow channels to the anode catalyst layers, but inhibits oxygen transport. While some of the water required by the anode is supplied by the water produced in the cathode, the majority of water must be supplied by the anode gas phase, making operation with fully humidified reactants necessary. The length of the gas flow channel has a significant effect on the current production of the PEM fuel cell, with a longer channel length having a lower performance relative to a shorter channel length. This lower performance is caused by a greater variation in water content within the longer channel length

CarbonNanoTubes (CNT) in bipolar plates for PEM fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Grundler, M.; Derieth, T.; Beckhaus, P.; Heinzel, A. [centre for fuel cell technology ZBT GmbH (Germany)

2010-07-01

Using standard mass production techniques for the fabrication of fuel cell components, such as bipolar plates, is a main issue for the commercialisation of PEM fuel cell systems. Bipolar plates contribute significantly to the cost structure of PEM stacks. In an upcoming fuel cell market a large number of bipolar plates with specific high-quality standards will be needed. At the Centre for Fuel Cell Technology (ZBT) together with the University of Duisburg-Essen fuel cell stacks based on injection moulded bipolar plates have been developed and demonstrated successfully [1]. This paper focuses on the interactions between carbon filling materials (graphite, carbon black and carbon nanotubes (CNT)) in compound based bipolar plates and especially the potential of CNTs, which were used in bipolar plates for the first time. The entire value added chain based on the feedstock, the compounding and injection moulding process, the component bipolar plate, up to the operation of a PEM single fuel cell stack with CNT-based bipolar plates is disclosed. (orig.)

Degradation mechanisms and accelerated testing in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

2010-01-01

The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Although there has been recent progress in improving durability, further improvements are needed to meet the commercialization targets. Past improvements have largely been made possible because of the fundamental understanding of the underlying degradation mechanisms. By investigating component and cell degradation modes; defining the fundamental degradation mechanisms of components and component interactions new materials can be designed to improve durability. Various factors have been shown to affect the useful life of PEM fuel cells. Other issues arise from component optimization. Operational conditions (such as impurities in either the fuel and oxidant stream), cell environment, temperature (including subfreezing exposure), pressure, current, voltage, etc.; or transient versus continuous operation, including start-up and shutdown procedures, represent other factors that can affect cell performance and durability. The need for Accelerated Stress Tests (ASTs) can be quickly understood given the target lives for fuel cell systems: 5000 hours ({approx} 7 months) for automotive, and 40,000 hrs ({approx} 4.6 years) for stationary systems. Thus testing methods that enable more rapid screening of individual components to determine their durability characteristics, such as off-line environmental testing, are needed for evaluating new component durability in a reasonable turn-around time. This allows proposed improvements in a component to be evaluated rapidly and independently, subsequently allowing rapid advancement in PEM fuel cell durability. These tests are also crucial to developers in order to make sure that they do not sacrifice durability while making improvements in costs (e.g. lower platinum group metal [PGM] loading) and performance (e.g. thinner membrane or a GDL with better water management properties). To

The pharmacology of regenerative medicine.

Science.gov (United States)

Christ, George J; Saul, Justin M; Furth, Mark E; Andersson, Karl-Erik

2013-07-01

Regenerative medicine is a rapidly evolving multidisciplinary, translational research enterprise whose explicit purpose is to advance technologies for the repair and replacement of damaged cells, tissues, and organs. Scientific progress in the field has been steady and expectations for its robust clinical application continue to rise. The major thesis of this review is that the pharmacological sciences will contribute critically to the accelerated translational progress and clinical utility of regenerative medicine technologies. In 2007, we coined the phrase "regenerative pharmacology" to describe the enormous possibilities that could occur at the interface between pharmacology, regenerative medicine, and tissue engineering. The operational definition of regenerative pharmacology is "the application of pharmacological sciences to accelerate, optimize, and characterize (either in vitro or in vivo) the development, maturation, and function of bioengineered and regenerating tissues." As such, regenerative pharmacology seeks to cure disease through restoration of tissue/organ function. This strategy is distinct from standard pharmacotherapy, which is often limited to the amelioration of symptoms. Our goal here is to get pharmacologists more involved in this field of research by exposing them to the tools, opportunities, challenges, and interdisciplinary expertise that will be required to ensure awareness and galvanize involvement. To this end, we illustrate ways in which the pharmacological sciences can drive future innovations in regenerative medicine and tissue engineering and thus help to revolutionize the discovery of curative therapeutics. Hopefully, the broad foundational knowledge provided herein will spark sustained conversations among experts in diverse fields of scientific research to the benefit of all.

Design and construction of an electrolyte PEM test; Diseno y construccion de un electrolizador PEM de prueba

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Huerta, R. G.; Santillan-Aragon, G. [Instituto Politecnico Nacional, Mexico, D.F. (Mexico)]. E-mail: rosgonzalez_h@yahoo.com.mx; Solorza-Feria, O. [CINVESTAV-IPN, Mexico D.F. (Mexico)

2009-09-15

The use of hydrogen as a fuel is directly linked to its efficient and clean production. One of the most promising methods is water electrolysis, which coupled with a renewable energy source prevents the emission of pollutants into the atmosphere. If a proton exchange membrane (PEM) electrolysis is used, a highly pure hydrogen is produced, ready to be used in a fuel battery. Many studies and investigations in this area concentrate on finding different stable and selective electrocatalysts for the cathode reaction (production of hydrogen) and anode reaction (production of oxygen). To conduct these studies, equipment is needed to perform electrochemical studies and determine the stability and performance of different electrocatalysts. This work presents the design and construction of an a PEM electrolysis test to determine the performance of different anode electrocatalysts. Its active area is 4 cm{sup 2}, its structure is graphite and the current distribution mesh is made of stainless steel. Its performance was determined using as electrocatalysts 10% Pt/C E-tek® anodes and a 50%-50%, 25%-75% and 75%-25% combination of RuO{sub 2}-IrO{sub 2}. The authors wish to thank the ICYTDF (PICS08-37) for financial support and IPN (SIP-20090433) and architect Nestor Romero for the electrolysis machining. [Spanish] La utilizacion del hidrogeno como combustible esta ligado directamente a su produccion eficiente y limpia, uno de los metodos mas prometedores es la electrolisis del agua, ya que acoplado con una fuente de energia renovable se evita la emision de contaminantes a la atmosfera. Si se utiliza un electrolizador de membrana de intercambio protonico (Tipo PEM), el hidrogeno que se produce es de alta pureza, listo para ser utilizado en una pila de combustible. Muchos estudios e investigaciones en esta area se concentran en encontrar distintos electrocatalizadores estables y selectivos para la reaccion catodica (produccion de hidrogeno) y anodica (produccion de oxigeno). Para

Structural and Morphological Features of Acid-Bearing Polymers for PEM Fuel Cells

DEFF Research Database (Denmark)

Yang, Yunsong; Siu, Ana; Peckham, Timothy J.

2008-01-01

Chemical structure, polymer microstructure, sequence distribution, and morphology of acid-bearing polymers are important factors in the design of polymer electrolyte membranes (PEMs) for fuel cells. The roles of ion aggregation and phase separation in vinylic- and aromatic-based polymers in proton...... conductivity and water transport are described. The formation, dimensions, and connectivity of ionic pathways are consistently found to play an important role in determining the physicochemical properties of PEMs. For polymers that possess low water content, phase separation and ionic channel formation...

Psychometric Evaluation of the Young Children's Participation and Environment Measure (YC-PEM) for use in Singapore.

Science.gov (United States)

Lim, Chun Yi; Law, Mary; Khetani, Mary; Rosenbaum, Peter; Pollock, Nancy

2018-08-01

To estimate the psychometric properties of a culturally adapted version of the Young Children's Participation and Environment Measure (YC-PEM) for use among Singaporean families. This is a prospective cohort study. Caregivers of 151 Singaporean children with (n = 83) and without (n = 68) developmental disabilities, between 0 and 7 years, completed the YC-PEM (Singapore) questionnaire with 3 participation scales (frequency, involvement, and change desired) and 1 environment scale for three settings: home, childcare/preschool, and community. Setting-specific estimates of internal consistency, test-retest reliability, and construct validity were obtained. Internal consistency estimates varied from .59 to .92 for the participation scales and .73 to .79 for the environment scale. Test-retest reliability estimates from the YC-PEM conducted on two occasions, 2-3 weeks apart, varied from .39 to .89 for the participation scales and from .65 to .80 for the environment scale. Moderate to large differences were found in participation and perceived environmental support between children with and without a disability. YC-PEM (Singapore) scales have adequate psychometric properties except for low internal consistency for the childcare/preschool participation frequency scale and low test-retest reliability for home participation frequency scale. The YC-PEM (Singapore) may be used for population-level studies involving young children with and without developmental disabilities.

Simulation study of a PEM fuel cell system fed by hydrogen produced by partial oxidation

Energy Technology Data Exchange (ETDEWEB)

Ozdogan, S [Marmara University, Faculty of Engineering, Istanbul (Turkey); Ersoz, A; Olgun, H [TUBITAK Marmara Research Center, Energy Systems and Environmental Research Institute, Kocaeli (Turkey)

2003-09-01

Within the frame of sustainable development, efficient and clean, if possible zero emission energy production technologies are of utmost importance in various sectors such as utilities, industry, households and transportation. Low-temperature fuel cell systems are suitable for powering transportation systems such as automobiles and trucks in an efficient and low-emitting manner. Proton exchange membrane (PEM) fuel cell systems constitute the most promising low temperature fuel cell option being developed globally. PEM fuel cells generate electric power from air and hydrogen or from a hydrogen rich gas via electrochemical reactions. Water and waste heat are the only by-products of PEM fuel cells. There is great interest in converting current hydrocarbon based common transportation fuels such as gasoline and diesel into hydrogen rich gases acceptable by PEM fuel cells. Hydrogen rich gases can be produced from conventional transportation fuels via various reforming technologies. Steam reforming, partial oxidation and auto-thermal reforming are the three major reforming technologies. In this paper, we discuss the results of a simulation study for a PEM fuel cell with partial oxidation. The Aspen HYSYS 3.1 code has been used for simulation purposes. Two liquid hydrocarbon fuels have been selected to investigate the effect of average molecular weights of hydrocarbons, on the fuel processing efficiency. The overall system efficiency depends on the fuel preparation and fuel cell efficiencies as well as on the heat integration within the system. It is desired to investigate the overall system efficiencies for net electrical power production at 100 kW considering bigger scale transport applications. Results indicate that fuel properties, fuel preparation system operating parameters and PEM fuel cell polarization curve characteristics all affect the overall system efficiency. (authors)

Development of an approach to correcting MicroPEM baseline drift.

Science.gov (United States)

Zhang, Ting; Chillrud, Steven N; Pitiranggon, Masha; Ross, James; Ji, Junfeng; Yan, Beizhan

2018-07-01

Fine particulate matter (PM 2.5 ) is associated with various adverse health outcomes. The MicroPEM (RTI, NC), a miniaturized real-time portable particulate sensor with an integrated filter for collecting particles, has been widely used for personal PM 2.5 exposure assessment. Five-day deployments were targeted on a total of 142 deployments (personal or residential) to obtain real-time PM 2.5 levels from children living in New York City and Baltimore. Among these 142 deployments, 79 applied high-efficiency particulate air (HEPA) filters in the field at the beginning and end of each deployment to adjust the zero level of the nephelometer. However, unacceptable baseline drift was observed in a large fraction (> 40%) of acquisitions in this study even after HEPA correction. This drift issue has been observed in several other studies as well. The purpose of the present study is to develop an algorithm to correct the baseline drift in MicroPEM based on central site ambient data during inactive time periods. A running baseline & gravimetric correction (RBGC) method was developed based on the comparison of MicroPEM readings during inactive periods to ambient PM 2.5 levels provided by fixed monitoring sites and the gravimetric weight of PM 2.5 collected on the MicroPEM filters. The results after RBGC correction were compared with those using HEPA approach and gravimetric correction alone. Seven pairs of duplicate acquisitions were used to validate the RBGC method. The percentages of acquisitions with baseline drift problems were 42%, 53% and 10% for raw, HEPA corrected, and RBGC corrected data, respectively. Pearson correlation analysis of duplicates showed an increase in the coefficient of determination from 0.75 for raw data to 0.97 after RBGC correction. In addition, the slope of the regression line increased from 0.60 for raw data to 1.00 after RBGC correction. The RBGC approach corrected the baseline drift issue associated with MicroPEM data. The algorithm developed

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...

Phase 1 feasibility study of an integrated hydrogen PEM fuel cell system. Final report

Energy Technology Data Exchange (ETDEWEB)

Luczak, F.

1998-03-01

Evaluated in the report is the use of hydrogen fueled proton exchange membrane (PEM) fuel cells for devices requiring less than 15 kW. Metal hydrides were specifically analyzed as a method of storing hydrogen. There is a business and technical part to the study that were developed with feedback from each other. The business potential of a small PEM product is reviewed by examining the markets, projected sales, and required investment. The major technical and cost hurdles to a product are also reviewed including: the membrane and electrode assembly (M and EA), water transport plate (WTP), and the metal hydrides. It was concluded that the best potential stationary market for hydrogen PEM fuel cell less than 15 kW is for backup power use in telecommunications applications.

Performance and quality control of Clear-PEM detector modules

International Nuclear Information System (INIS)

Amaral, Pedro; Carrico, Bruno; Ferreira, Miguel; Moura, Rui; Ortigao, Catarina; Rodrigues, Pedro; Da Silva, Jose C.; Trindade, Andreia; Varela, Joao

2007-01-01

Clear-PEM is a dedicated PET scanner for breast and axilla cancer diagnosis, under development within the framework of the Crystal Clear Collaboration at CERN, aiming at the detection of tumors down to 2 mm in diameter. The camera consists of two planar detector heads with active dimensions 16.0x14.5 cm 2 . Each head has 96 Clear-PEM detector modules consisting of 32 LYSO:Ce pixels with dimensions 2x2x20 mm 3 packed in a 4x8 BaSO 4 reflector matrix compressed between two Hamamatsu S8550 APD arrays in a double-readout configuration for Depth-of-Interaction (DoI) determination. The modules are individually measured and characterized before being grouped into Supermodules (comprised of 24 modules). Measured properties include photo-peak position, relative gain dispersion, energy resolution, cross-talk and DoI resolution. Optical inspection of matrices was also performed with the aid of a microscope, to search for pixel misalignments and matrix defects. Modules' performance was thoroughly evaluated with a 511 keV collimated beam to exactly determine DoI resolution. In addition, a fast quality control (QC) procedure using flood irradiations from a 137 Cs source was applied systematically. The overall performance of the 24 detector modules complies with the design goals of the Clear-PEM detector, showing energy resolution around 15%, DoI resolution of about 2 mm and gain dispersion among pixels of 15%

REGEN: Ancestral Genome Reconstruction for Bacteria.

Science.gov (United States)

Yang, Kuan; Heath, Lenwood S; Setubal, João C

2012-07-18

Ancestral genome reconstruction can be understood as a phylogenetic study with more details than a traditional phylogenetic tree reconstruction. We present a new computational system called REGEN for ancestral bacterial genome reconstruction at both the gene and replicon levels. REGEN reconstructs gene content, contiguous gene runs, and replicon structure for each ancestral genome. Along each branch of the phylogenetic tree, REGEN infers evolutionary events, including gene creation and deletion and replicon fission and fusion. The reconstruction can be performed by either a maximum parsimony or a maximum likelihood method. Gene content reconstruction is based on the concept of neighboring gene pairs. REGEN was designed to be used with any set of genomes that are sufficiently related, which will usually be the case for bacteria within the same taxonomic order. We evaluated REGEN using simulated genomes and genomes in the Rhizobiales order.

Bi-polarized translation of ascidian maternal mRNA determinant pem-1 associated with regulators of the translation machinery on cortical Endoplasmic Reticulum (cER).

Science.gov (United States)

Paix, Alexandre; Le Nguyen, Phuong Ngan; Sardet, Christian

2011-09-01

Polarized cortical mRNA determinants such as maternal macho-1 and pem-1 in ascidians, like budding yeast mating factor ASH1 reside on the cER-mRNA domain a subdomain of cortical Endoplasmic Reticulum(ER) and are translated in its vicinity. Using high resolution imaging and isolated cortical fragments prepared from eggs and embryos we now find that macho-1 and pem-1 RNAs co-localize with phospho-protein regulators of translation initiation (MnK/4EBP/S6K). Translation of cortical pem-1 RNA follows its bi-polarized relocalization. About 10 min after fertilization or artificial activation with a calcium ionophore, PEM1 protein is detected in the vegetal cortex in the vicinity of pem-1 RNA. About 40 min after fertilization-when pem-1 RNA and P-MnK move to the posterior pole-PEM1 protein remains in place forming a network of cortical patches anchored at the level of the zygote plasma membrane before disappearing. Cortical PEM1 protein is detected again at the 4 cell stage in the posterior centrosome attracting body (CAB) region where the cER-mRNA domain harboring pem-1/P-MnK/P-4EBP/P-S6K is concentrated. Bi-polarized PEM1 protein signals are not detected when pem-1 morpholinos are injected into eggs or zygotes or when MnK is inhibited. We propose that localized translation of the pem-1 RNA determinant is triggered by the fertilization/calcium wave and that the process is controlled by phospho-protein regulators of translation initiation co-localized with the RNA determinant on a sub-domain of the cortical Endoplasmic Reticulum. Copyright © 2011 Elsevier Inc. All rights reserved.

Adaptive Process Controls and Ultrasonics for High Temperature PEM MEA Manufacture

Energy Technology Data Exchange (ETDEWEB)

Walczyk, Daniel F. [Rensselaer Polytechnic Inst., Troy, NY (United States)

2015-08-26

The purpose of this 5-year DOE-sponsored project was to address major process bottlenecks associated with fuel cell manufacturing. New technologies were developed to significantly reduce pressing cycle time for high temperature PEM membrane electrode assembly (MEA) through the use of novel, robust ultrasonic (U/S) bonding processes along with low temperature (<100°C) PEM MEAs. In addition, greater manufacturing uniformity and performance was achieved through (a) an investigation into the causes of excessive variation in ultrasonically and thermally bonded MEAs using more diagnostics applied during the entire fabrication and cell build process, and (b) development of rapid, yet simple quality control measurement techniques for use by industry.

Simulation results of a veto counter for the ClearPEM

CERN Document Server

Trummer, J; Lecoq, P

2009-01-01

The Crystal Clear Collaboration (CCC) has built a prototype of a novel positron emission tomograph dedicated to functional breast imaging, the ClearPEM. The ClearPEM uses the common radio pharmaceutical FDG for imaging cancer. As FDG is a rather non-specific radio tracer, it accumulates not only in cancer cells but in all cells with a high energy consumption, such as the heart and liver. This fact poses a problem especially in breast imaging, where the vicinity of the heart and other organs to the breast leads to a high background noise level in the scanner. In this work, a veto counter to reduce the background is described. Different configurations and their effectiveness were studied using the GATE simulation package.

Fuel cell processor with low-temperature PEM fuel cell - testing. Final report; Naturgasreformersystem med lavtgemperatur-PEM braendselsceller - TEST. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Bech-Madsen, J.

2006-11-03

The purpose of the project is to further develop a Danish natural gas reformer system including optimisation of subsystems and the overall system consisting of a natural gas reformer and fuel cell CHP generator. This will contribute to the evaluation of to what extend Denmark shall develop small reformer units for PEM fuel Cells. In the project a reformer system with a high degree of automatic control has been build that fulfils the CHP requirements to operation time, dynamics etc. This work, with a FP05 reformer unit, has given valuable results concerning the possibilities and limitations of the reformer technology for CHP usage. It is important that the reformer and fuel cell units are designed with matching yields to optimise efficiency, turn-down start-up time etc. The burner that delivers heat for the steam reaction shall be able to use natural gas as fuel. This gives the possibility of using existing burner technology. In addition this will improve the efficiency since it will not be necessary to reform natural gas to feed the burner. The large number of BoP components in the FP05 unit is primarily used for achieving good regulation dynamics and accuracy. To reduce the number of components, a CHP unit with few or only one operational point should be considered. A single point of operation will reduce the number of valves as well as the requirements to the control and regulation of the system. A large part of the reformer size is needed to meet the high demands for CO purification of the reformat. This purification results in a very narrow window of operation for the reformer system. By using more CO tolerant fuel cells this part of the system can be reduced or even eliminated. To test the developed automatic control it was planned to integrate the FP05 reformer with a 10kW CHP unit that was being build by IRD in a separate project. This unit was perfect in size for testing with the reformer. However due to a number of reasons it was not possible during the

Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging

Science.gov (United States)

Raylman, R. R.; Majewski, S.; Wojcik, R.; Weisenberger, A. G.; Kross, B.; Popov, V.

2001-06-01

Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of /sup 18/F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom. Finally, the effect of object size on image counts and a correction for this effect were explored. The imager used in this study consisted of two PEM detector heads mounted 20 cm apart on a Lorad biopsy apparatus. The results demonstrated that a majority of the accidental coincidence events (/spl sim/80%) detected by this system were produced by radiotracer uptake in the adipose and muscle tissue of the torso. The presence of accidental coincidence events was shown to reduce lesion detectability. Much of this effect was eliminated by correction of the images utilizing estimates of accidental-coincidence contamination acquired with delayed coincidence circuitry built into the PEM system. The Compton scatter fraction for this system was /spl sim/14%. Utilization of a new scatter correction algorithm reduced the scatter fraction to /spl sim/1.5%. Finally, reduction of count recovery due to object size was measured and a correction to the data applied. Application of correction techniques

REGEN: Ancestral Genome Reconstruction for Bacteria

Directory of Open Access Journals (Sweden)

João C. Setubal

2012-07-01

Full Text Available Ancestral genome reconstruction can be understood as a phylogenetic study with more details than a traditional phylogenetic tree reconstruction. We present a new computational system called REGEN for ancestral bacterial genome reconstruction at both the gene and replicon levels. REGEN reconstructs gene content, contiguous gene runs, and replicon structure for each ancestral genome. Along each branch of the phylogenetic tree, REGEN infers evolutionary events, including gene creation and deletion and replicon fission and fusion. The reconstruction can be performed by either a maximum parsimony or a maximum likelihood method. Gene content reconstruction is based on the concept of neighboring gene pairs. REGEN was designed to be used with any set of genomes that are sufficiently related, which will usually be the case for bacteria within the same taxonomic order. We evaluated REGEN using simulated genomes and genomes in the Rhizobiales order.

Changes in Regenerative Capacity through Lifespan

Directory of Open Access Journals (Sweden)

Maximina H. Yun

2015-10-01

Full Text Available Most organisms experience changes in regenerative abilities through their lifespan. During aging, numerous tissues exhibit a progressive decline in homeostasis and regeneration that results in tissue degeneration, malfunction and pathology. The mechanisms responsible for this decay are both cell intrinsic, such as cellular senescence, as well as cell-extrinsic, such as changes in the regenerative environment. Understanding how these mechanisms impact on regenerative processes is essential to devise therapeutic approaches to improve tissue regeneration and extend healthspan. This review offers an overview of how regenerative abilities change through lifespan in various organisms, the factors that underlie such changes and the avenues for therapeutic intervention. It focuses on established models of mammalian regeneration as well as on models in which regenerative abilities do not decline with age, as these can deliver valuable insights for our understanding of the interplay between regeneration and aging.

Regenerative Rehabilitation – a New Future?

Science.gov (United States)

Perez-Terzic, Carmen; Childers, Martin K.

2014-01-01

Modern rehabilitation medicine is propelled by newfound knowledge aimed at offering solutions for an increasingly aging population afflicted by chronic debilitating conditions. Considered a core component of future healthcare, the roll-out of regenerative medicine underscores a paradigm shift in patient management targeted at restoring physiologic function and restituting normative impact. Nascent regenerative technologies offer unprecedented prospects in achieving repair of degenerated, diseased or damaged tissues. In this context, principles of regenerative science are increasingly integrated in rehabilitation practices as illustrated in the present Supplement. Encompassing a growing multidisciplinary domain, the emergent era of “regenerative rehabilitation” brings radical innovations at the forefront of healthcare blueprints. PMID:25310603

Risk Assessment for Distribution Systems Using an Improved PEM-Based Method Considering Wind and Photovoltaic Power Distribution

Directory of Open Access Journals (Sweden)

Qingwu Gong

2017-03-01

Full Text Available The intermittency and variability of permeated distributed generators (DGs could cause many critical security and economy risks to distribution systems. This paper applied a certain mathematical distribution to imitate the output variability and uncertainty of DGs. Then, four risk indices—EENS (expected energy not supplied, PLC (probability of load curtailment, EFLC (expected frequency of load curtailment, and SI (severity index—were established to reflect the system risk level of the distribution system. For the certain mathematical distribution of the DGs’ output power, an improved PEM (point estimate method-based method was proposed to calculate these four system risk indices. In this improved PEM-based method, an enumeration method was used to list the states of distribution systems, and an improved PEM was developed to deal with the uncertainties of DGs, and the value of load curtailment in distribution systems was calculated by an optimal power flow algorithm. Finally, the effectiveness and advantages of this proposed PEM-based method for distribution system assessment were verified by testing a modified IEEE 30-bus system. Simulation results have shown that this proposed PEM-based method has a high computational accuracy and highly reduced computational costs compared with other risk assessment methods and is very effective for risk assessments.

Novel High Temperature Membrane for PEM Fuel Cells, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The innovation proposed in this STTR program is a high temperature membrane to increase the efficiency and power density of PEM fuel cells. The NASA application is...

UARS Particle Environment Monitor (PEM) Level 3TP V001

Data.gov (United States)

National Aeronautics and Space Administration — The Particle Environment Monitor (PEM) Level 3TP data product consists of daily, 65.536 second and 2.048 interval time-ordered, vertical profiles of electron and...

Design of metallic bipolar plates for PEM fuel cells.

Science.gov (United States)

2012-01-01

This project focused on the design and production of metallic bipolar plates for use in PEM fuel cells. Different metals were explored : and stainless steel was found out to be best suited to our purpose. Following the selection of metal, it was calc...

An efficient mathematical model for air-breathing PEM fuel cells

International Nuclear Information System (INIS)

Ismail, M.S.; Ingham, D.B.; Hughes, K.J.; Ma, L.; Pourkashanian, M.

2014-01-01

Graphical abstract: The effects of the ambient humidity on the performance of air-breathing PEM fuel cells become more pronounced as the ambient temperature increases. The polarisation curves have been generated using the in-house developed MATLAB® application, Polarisation Curve Generator, which is available in the supplementary data. - Highlights: • An efficient mathematical model has been developed for an air-breathing PEM fuel cell. • The fuel cell performance is significantly over-predicted if the Joule and entropic heats are neglected. • The fuel cell performance is highly sensitive to the state of water at the thermodynamic equilibrium. • The cell potential dictates the favourable ambient conditions for the fuel cell. - Abstract: A simple and efficient mathematical model for air-breathing proton exchange membrane (PEM) fuel cells has been built. One of the major objectives of this study is to investigate the effects of the Joule and entropic heat sources, which are often neglected, on the performance of air-breathing PEM fuel cells. It is found that the fuel cell performance is significantly over-predicted if one or both of these heat sources is not incorporated into the model. Also, it is found that the performance of the fuel cell is highly sensitive to the state of the water at the thermodynamic equilibrium magnitude as both the entropic heat and the Nernst potential considerably increase if water is assumed to be produced in liquid form rather than in vapour form. Further, the heat of condensation is shown to be small and therefore, under single-phase modelling, has a negligible effect on the performance of the fuel cell. Finally, the favourable ambient conditions depend on the operating cell potential. At intermediate cell potentials, a mild ambient temperature and low humidity are favoured to maintain high membrane conductivity and mitigate water flooding. At low cell potentials, low ambient temperature and high humidity are favoured to

REGEN: Ancestral Genome Reconstruction for Bacteria

OpenAIRE

Yang, Kuan; Heath, Lenwood S.; Setubal, João C.

2012-01-01

Ancestral genome reconstruction can be understood as a phylogenetic study with more details than a traditional phylogenetic tree reconstruction. We present a new computational system called REGEN for ancestral bacterial genome reconstruction at both the gene and replicon levels. REGEN reconstructs gene content, contiguous gene runs, and replicon structure for each ancestral genome. Along each branch of the phylogenetic tree, REGEN infers evolutionary events, including gene creation and deleti...

A parametric study of assembly pressure, thermal expansion, and membrane swelling in PEM fuel cells

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2016-01-01

Proton Exchange membrane (PEM) fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, durability, reliability, manufacturability and cost-effectiveness. PEM fuel cell assembly pressure is known to cause large strains in the cell components. All components ...

Regenerative Therapy for Retinal Disorders

Directory of Open Access Journals (Sweden)

Narsis Daftarian

2010-01-01

Full Text Available Major advances in various disciplines of basic sciences including embryology, molecular and cell biology, genetics, and nanotechnology, as well as stem cell biology have opened new horizons for regenerative therapy. The unique characteristics of stem cells prompt a sound understanding for their use in modern regenerative therapies. This review article discusses stem cells, developmental stages of the eye field, eye field transcriptional factors, and endogenous and exogenous sources of stem cells. Recent studies and challenges in the application of stem cells for retinal pigment epithelial degeneration models will be summarized followed by obstacles facing regenerative therapy.

Researches on regenerative medicine-current state and prospect.

Science.gov (United States)

Wang, Zheng-Guo; Xiao, Kai

2012-01-01

Since 1980s, the rapid development of tissue engineering and stem cell research has pushed regenerative medicine to a new fastigium, and regenerative medicine has become a noticeable research field in the international biology and medicine. In China, about 100 million patients need repair and regeneration treatment every year, while the number is much larger in the world. Regenerative medicine could provide effective salvation for these patients. Both Chinese Academy of Sciences and Chinese Academy of Engineering have made roadmaps of 2010-2050 and 2011-2030 for regenerative medicine. The final goal of the two roadmaps is to make China go up to leading position in most research aspects of regenerative medicine. In accord with this strategy, the government and some enterprises have invested 3-5 billion RMB (0.5-0.8 billion USD) for the research on regenerative medicine. In order to push the translation of regenerative medicine forward-from bench to bedside, a strategic alliance has been established, and it includes 27 top-level research institutes, medical institutes, colleges, universities and enterprises in the field of stem cell and regeneration medicine. Recently the journal, Science, has published a special issue-Regenerative Medicine in China, consisting of 35 papers dealing with stem cell and regeneration, tissue engineering and regeneration, trauma and regeneration and bases for tissue repair and regenerative medicine. It is predicated that a greater breakthrough in theory and practice of regenerative medicine will be achieved in the near future (20 to 30 years).

Generation of thyroid follicular cells from pluripotent stem cells: Potential for regenerative medicine

Directory of Open Access Journals (Sweden)

Will eSewell

2014-06-01

Full Text Available Nearly 12 percent of the population in the United States will be afflicted with a thyroid related disorder during their lifetime. Common treatment approaches are tailored to the specific disorder and include surgery, radioactive iodine ablation, antithyroid drugs, thyroid hormone replacement, external beam radiation, and chemotherapy. Regenerative medicine endeavors to combat disease by replacing or regenerating damaged, diseased or dysfunctional body parts. A series of achievements in pluripotent stem cell research have transformed regenerative medicine in many ways by demonstrating repair of a number of body parts in mice, of which, the thyroid has now been inducted into this special group. Seminal work in pluripotent cells, namely embryonic stem cells and induced pluripotent stem cells, have made possible their path to becoming key tools and biological building blocks for cell-based regenerative medicine to combat the gamut of human diseases, including those affecting the thyroid.

Using the PAW/PEM monitoring systems to support operations at Point Lepreau

International Nuclear Information System (INIS)

MacDonald, S.; McIntyre, M.; Dai, H.

1997-01-01

The plant data logger was brought on-line at the Point Lepreau Generating Station (PLGS) in 1992 in order to record information from instruments throughout the plant. Using the System Engineers Data Extraction (SEDE) utility, current plant data is at the fingertips of anyone with a network connection. System engineers can monitor the performance of their systems at any time and take pro-active measures to avoid problems with performance, as well as monitor behaviour during tests and plant upsets. Nuclear Safety personnel gather data for use in simulation and analysis validation, as well as to ensure that plant parameters are kept within the safe operating envelope. The PLGS operational safety group embarked on a project to develop a data management system. The project and the monitoring process has come to be known as the Plant Analysis Workbench (PAW). When the need for complex monitoring of safety system signals was identified, this led to a similar project called the Plant Expert Monitor (PEM). In this paper we present an overview of the functionality of both PAW and PEM, outlining in particular the expert system architecture in PEM and giving an example of its day-to-day use

Final Scientific Report, New Proton Conductive Composite Materials for PEM Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Lvov, Serguei

2010-11-08

This project covered one of the main challenges in present-day PEM fuel cell technology: to design a membrane capable of maintaining high conductivity and mechanical integrity when temperature is elevated and water vapor pressure is severely reduced. The DOE conductivity milestone of 0.1 S cm-1 at 120 degrees C and 50 % relative humidity (RH) for designed membranes addressed the target for the project. Our approach presumed to develop a composite membrane with hydrophilic proton-conductive inorganic material and the proton conductive polymeric matrix that is able to “bridge” the conduction paths in the membrane. The unique aspect of our approach was the use of highly functionalized inorganic additives to benefit from their water retention properties and high conductivity as well. A promising result turns out that highly hydrophilic phosphorsilicate gels added in Nafion matrix improved PEM fuel cell performance by over 50% compared with bare Nafion membrane at 120 degrees C and 50 % RH. This achievement realizes that the fuel cell operating pressure can be kept low, which would make the PEM fuel cell much more cost efficient and adaptable to practical operating conditions and facilitate its faster commercialization particularly in automotive and stationary applications.

High Temperature PEM Fuel Cell Systems, Control and Diagnostics

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Kær, Søren Knudsen; Justesen, Kristian Kjær

2015-01-01

fuels utilizes one of the main advantages of the high temperature PEM fuel cell: robustness to fuel quality and impurities. In order for such systems to provide efficient, robust, and reliable energy, proper control strategies are needed. The complexity and nonlinearity of many of the components...

Summary of: Regenerative endodontics.

Science.gov (United States)

Clark, Stephen J

2014-03-01

Significant advances in our understanding of the biological processes involved in tooth development and repair at the cellular and molecular levels have underpinned the newly emerging area of regenerative endodontics. Development of treatment protocols based on exploiting the natural wound healing properties of the dental pulp and applying tissue engineering principles has allowed reporting of case series showing preservation of tissue vitality and apexogenesis. To review current case series reporting regenerative endodontics. Current treatment approaches tend to stimulate more reparative than regenerative responses in respect of the new tissue generated, which often does not closely resemble the physiological structure of dentine-pulp. However, despite these biological limitations, such techniques appear to offer significant promise for improved treatment outcomes. Improved biological outcomes will likely emerge from the many experimental studies being reported and will further contribute to improvements in clinical treatment protocols.

Synchrotron radiography and tomography of a PEM fuel cell; Synchrotron-Radiographie und -Tomographie einer PEM-Brennstoffzelle

Energy Technology Data Exchange (ETDEWEB)

Markoetter, Henning; Manke, Ingo [Helmholtzzentrum Berlin fuer Materialien und Energie, Berlin (Germany). Fachgruppe Bildgebende Verfahren; Arlt, Tobias [TU Berlin, Berlin (Germany); Banhart, John [TU Berlin, Institut fuer angewandte Materialforschung, Berlin (Germany); TU Berlin, Institut fuer Werkstoffwissenschaften und -technologien, Berlin (Germany); Riesemeier, Heinrich [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Arbeitsgruppe Synchrotronstrahlanalytik (Germany); Krueger, Philipp [CONSULECTRA Unternehmensberatung GmbH, Hamburg (Germany); Haussmann, Jan; Klages, Merle [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung, Stuttgart (Germany); Scholta, Joachim [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung, Stuttgart (Germany). Fachgruppe Brennstoffzellen-Stacks

2013-06-01

The three dimensional water distribution and transport pathways in gas diffusion layers (GDL) of a polymer electrolyte membrane fuell cell (PEM FC) are analysed at various operating conditions. The method of quasi in-situ X-ray tomography is used for a three dimensional visualization of the water distribution and the GDL structure. Based on the results of dynamic radiographic measurements water transport pathways are located and subsequently investigated in detail by means of tomography. The combination of 2D and 3D techniques allows for an identification of 3D transport pathways through the GDl.

Polymers and composites synthesis and characterization for application on PEM type fuel cells; Sintese e caracterizacao de polimeros e compositos para aplicacao em celulas a combustivel do tipo PEM

Energy Technology Data Exchange (ETDEWEB)

Fiuza, Raigenis da Paz; Souza, Daniele Ribeiro; Barreto, Ednardo Gomes; Boaventura Filho, Jaime Soares; Jose, Nadia Mamede [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil)]. E-mail: raigenis@gmail.com

2006-07-01

The PEM (proton exchanging membrane) type fuel cell presents good potential for the energy production without the residue generation. However, its manufacture presents high costs for commercial application, mainly due to the electrolyte. Sulfonated Peek (polish-ether-ether-ketone) supported or auto immobilized the in a silicone matrix is an interesting alternative as electrolyte for PEM fuel cells. The commercial PEEK in powder form was functionalized with sulfuric acid, giving the SPEEK (Sulfonated PEEK). The membranes were produced by hot pressing the SPEEK immobilized in a silicone matrix produced by the sol-gel process. The membranes obtained were characterized by DRX, FTIR, TGA, MEV, DSC and protonic conductivity measurements. (author)

400 W High Temperature PEM Fuel Cell Stack Test

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Kær, Søren Knudsen

2006-01-01

This work demonstrates the operation of a 30 cell high temperature PEM (HTPEM) fuel cell stack. This prototype stack has been developed at the Institute of Energy Technology, Aalborg University, as a proof-of-concept for a low pressure cathode air cooled HTPEM stack. The membranes used are Celtec...

A review of the regenerative endodontic treatment procedure

Directory of Open Access Journals (Sweden)

Bin-Na Lee,

2015-08-01

Full Text Available Traditionally, apexification has been used to treat immature permanent teeth that have lost pulp vitality. This technique promotes the formation of an apical barrier to close the open apex so that the filling materials can be confined to the root canal. Because tissue regeneration cannot be achieved with apexification, a new technique called regenerative endodontic treatment was presented recently to treat immature permanent teeth. Regenerative endodontic treatment is a treatment procedure designed to replace damaged pulp tissue with viable tissue which restores the normal function of the pulp-dentin structure. After regenerative endodontic treatment, continued root development and hard tissue deposition on the dentinal wall can occur under ideal circumstances. However, it is difficult to predict the result of regenerative endodontic treatment. Therefore, the purpose of this study was to summarize multiple factors effects on the result of regenerative endodontic treatment in order to achieve more predictable results. In this study, we investigated the features of regenerative endodontic treatment in comparison with those of other pulp treatment procedures and analyzed the factors that have an effect on regenerative endodontic treatment.

Regenerative endodontics: a comprehensive review.

Science.gov (United States)

Kim, S G; Malek, M; Sigurdsson, A; Lin, L M; Kahler, B

2018-05-19

The European Society of Endodontology and the American Association for Endodontists have released position statements and clinical considerations for regenerative endodontics. There is increasing literature on this field since the initial reports of Iwaya et al. (Dental Traumatology, 17, 2001, 185) and Banchs & Trope (Journal of Endodontics, 30, 2004, 196). Endogenous stem cells from an induced periapical bleeding and scaffolds using blood clot, platelet rich plasma or platelet-rich fibrin have been utilized in regenerative endodontics. This approach has been described as a 'paradigm shift' and considered the first treatment option for immature teeth with pulp necrosis. There are three treatment outcomes of regenerative endodontics; (i) resolution of clinical signs and symptoms; (ii) further root maturation; and (iii) return of neurogenesis. It is known that results are variable for these objectives, and true regeneration of the pulp/dentine complex is not achieved. Repair derived primarily from the periodontal and osseous tissues has been shown histologically. It is hoped that with the concept of tissue engineering, namely stem cells, scaffolds and signalling molecules, that true pulp regeneration is an achievable goal. This review discusses current knowledge as well as future directions for regenerative endodontics. Patient-centred outcomes such as tooth discolouration and possibly more appointments with the potential for adverse effects needs to be discussed with patients and parents. Based on the classification of Cvek (Endodontics and Dental Traumatology, 8, 1992, 45), it is proposed that regenerative endodontics should be considered for teeth with incomplete root formation although teeth with near or complete root formation may be more suited for conventional endodontic therapy or MTA barrier techniques. However, much is still not known about clinical and biological aspects of regenerative endodontics. © 2018 International Endodontic Journal. Published by

Use of hydrogen-deuterium exchange for contrast in {sup 1}H NMR microscopy investigations of an operating PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Feindel, Kirk W.; Bergens, Steven H.; Wasylishen, Roderick E. [Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alta. T6G 2G2 (Canada)

2007-11-08

The use of hydrogen-deuterium (H-D) exchange as a method to introduce contrast in {sup 1}H NMR microscopy images and to investigate the dynamic distribution of water throughout an operating H{sub 2}/O{sub 2} polymer electrolyte membrane fuel cell, PEMFC, is demonstrated. Cycling D{sub 2}O(l) through the flow channels of a PEMFC causes H-D exchange with water in the PEM to result in a D{sub 2}O-saturated PEM and thus concomitant removal of the {sup 1}H NMR signal. Subsequent operation of the PEMFC with H{sub 2}(g) enables visualization of the redistribution of water from wet or flooded conditions as H-D exchange occurs with D{sub 2}O in the PEM and results in recovery of the {sup 1}H NMR signal. Alternating between H{sub 2}(g) and D{sub 2}(g) as fuel allows observation of water distributions in the PEM while the cell is operating at a steady-state under low relative humidity. At similar currents, the rate of observable H-D exchange in the PEM during fuel cell operation was faster when the PEM was saturated with water than when under low relative humidity. These results are consistent with the known proportions of the conductive hydrophilic and nonconductive hydrophobic domains of Nafion when exposed to different relative humidities. (author)

ClearPEM: prototype PET device dedicated to breast imaging

CERN Multimedia

Joao Varela

2009-01-01

Clinical trials have begun in Portugal on a new breast imaging system (ClearPEM) using positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

Regenerative-filter-incinerator device

Energy Technology Data Exchange (ETDEWEB)

Rosebrock, T.L.

1977-10-18

A regenerative-filter-incinerator device, for use in the exhaust system of a diesel engine, includes a drum-like regenerative-heat exchanger-filter assembly rotatably mounted within a housing that is adapted to be installed directly in the exhaust gas stream discharged from a diesel engine as close to the engine as possible. The regenerative-heat exchanger-filter assembly provides an inner chamber which serves as a reaction chamber for the secondary combustion of exhaust gases including particulates discharged from the engine. The regenerative-heat exchanger-filter assembly includes separately rotatable heat exchange-filter elements pervious to radial flow of fluid therethrough and adapted to filter out particulates from the exhaust gases and to carry them into the reaction chamber. During engine operation, the reaction chamber is provided with a quantity of heat, as necessary, to effect secondary combustion of the exhaust gases and particulates by means of an auxiliary heat source and the heat generated within the reaction chamber is stored in the individual heat exchange-filter elements during the discharge of exhaust gases therethrough from the reaction chamber and this heat is then transferred to the inflowing volume of the exhaust gases so that, in effect, exhaust gas is discharged from the device at substantially the same temperature as it was during its inlet into the device from the engine.

Regenerative braking system of PM synchronous motor

Science.gov (United States)

Gao, Qian; Lv, Chengxing; Zhao, Na; Zang, Hechao; Jiang, Huilue; Zhang, Zhaowen; Zhang, Fengli

2018-04-01

Permanent-magnet synchronous motor is widely adopted in many fields with the advantage of a high efficiency and a high torque density. Regenerative Braking Systems (RBS) provide an efficient method to assist PMSM system achieve better fuel economy and lowering exhaust emissions. This paper describes the design and testing of the regenerative braking systems of PMSM. The mode of PWM duty has been adjusted to control regenerative braking of PMSM using energy controller for the port-controlled Hamiltonian model. The simulation analysis indicates that a smooth control could be realized and the highest efficiency and the smallest current ripple could be achieved by Regenerative Braking Systems.

Numerical Simulations and Diagnostic Studies of Meteorological Conditions During PEM-Tropics B

Science.gov (United States)

Fuelberg, Henry E.

2001-01-01

Provides a final report on the work accomplished by several meteorological scientists under a NASA grant in conjunction with the DC-8 component of Pacific Exploratory Mission (PEM)-Tropics B. The responsibilities of the principal investigator included collaboration with the Science Team on flight planning, presentation of forecasts, and the preparation of map discussions for each flight. In a published manuscript, the principal investigator summarized the meteorological conditions during PEM-TB which included mean flow patterns, subtropical anticyclones, the South Pacific Convergence Zone (SPCZ), and the Intertropical Convergence Zone (ITCZ). Methodologies used included streamlines, ten day backward trajectories, thermodynamic soundings, and satellite imagery. Other interests included air sampling for the purpose of determining pollution levels.

Habitat Demonstration Unit Project Leadership and Management Strategies

Science.gov (United States)

Kennedy, Kriss J.

2011-01-01

This paper gives an overview of the National Aeronautics and Space Administration (NASA) led multi-center Habitat Demonstration Unit (HDU) project leadership and management strategies. The HDU project team constructed and tested an analog prototype lunar surface habitat/laboratory called the Pressurized Excursion Module (PEM) during 2010. The prototype unit subsystems were integrated in a short amount of time, utilizing a tiger team approach that brought together over 20 habitation-related technologies and innovations from a variety of NASA centers. This paper describes the leadership and management strategies as well as lessons learned pertaining to leading and managing a multi-center diverse team in a rapid prototype environment. The PEM configuration went from a paper design to an operational surface habitat demonstration unit in less than 12 months. The HDU project is part of the strategic plan from the Exploration Systems Mission Directorate (ESMD) Directorate Integration Office (DIO) and the Exploration Mission Systems Office (EMSO) to test destination elements in analog environments. The 2011 HDU-Deep Space Habitat (DSH) configuration will build upon the PEM work, and emphasize validity of crew operations (remote working and living), EVA operations, mission operations, logistics operations, and science operations that might be required in a deep space context for Near Earth Object (NEO) exploration mission architectures. The 2011 HDU-DSH will be field-tested during the 2011 Desert Research and Technologies Studies (DRaTS) field tests. The HDU project is a "technology-pull" project that integrates technologies and innovations from multiple NASA centers. This project will repurpose the HDU 2010 demo unit that was field tested in the 2010 DRaTS, adding habitation functionality to the prototype unit. This paper will describe the strategy of establishing a multi-center project management team that put in place the key multi-center leadership skills and

Regenerative Perspective in Modern Dentistry

Directory of Open Access Journals (Sweden)

Mihnea Ioan Nicolescu

2016-04-01

Full Text Available This review aims to trace the contour lines of regenerative dentistry, to offer an introductory overview on this emerging field to both dental students and practitioners. The crystallized depiction of the concept is a translational approach, connecting dental academics to scientific research and clinical utility. Therefore, this review begins by presenting the general features of regenerative medicine, and then gradually introduces the specific aspects of major dental subdomains, highlighting the progress achieved during the last years by scientific research and, in some cases, which has already been translated into clinical results. The distinct characteristics of stem cells and their microenvironment, together with their diversity in the oral cavity, are put into the context of research and clinical use. Examples of regenerative studies regarding endodontic and periodontal compartments, as well as hard (alveolar bone and soft (salivary glands related tissues, are presented to make the reader further acquainted with the topic. Instead of providing a conclusion, we will emphasize the importance for all dental community members, from young students to experienced dentists, of an early awareness rising regarding biomedical research progress in general and regenerative dentistry in particular.

Current overview on challenges in regenerative endodontics

Science.gov (United States)

Bansal, Ramta; Jain, Aditya; Mittal, Sunandan

2015-01-01

Introduction: Regenerative endodontics provides hope of converting the non-vital tooth into vital once again. It focuses on substituting traumatized and pathological pulp with functional pulp tissue. Current regenerative procedures successfully produce root development but still fail to re-establish real pulp tissue and give unpredictable results. There are several drawbacks that need to be addressed to improve the quality and efficiency of the treatment. Aim: The aim of this review article is to discuss major priorities that ought to be dealt before applications of regenerative endodontics flourish the clinical practice. Materials and Methods: A web-based research on MEDLINE was done using filter terms Review, published in the last 10 years and Dental journals. Keywords used for research were “regenerative endodontics,” “dental stem cells,” “growth factor regeneration,” “scaffolds,” and “challenges in regeneration.” This review article screened about 150 articles and then the relevant information was compiled. Results: Inspite of the impressive growth in regenerative endodontic field, there are certain loopholes in the existing treatment protocols that might sometimes result in undesired and unpredictable outcomes. Conclusion: Considerable research and development efforts are required to improve and update existing regenerative endodontic strategies to make it an effective, safe, and biological mode to save teeth. PMID:25657518

Analysis of the Coupling Behavior of PEM Fuel Cells and DC-DC Converters

Directory of Open Access Journals (Sweden)

Achim Kienle

2009-03-01

Full Text Available The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, the overall behaviors of the coupled fuel cell-converter systems are analyzed. It is shown, that neither stationary multiplicities nor oscillations can be introduced by the couplings and therefore separate control approaches for both the PEMFC and the DC-DC converters are applicable.

Thermodynamic study of a regenerative atmospheric water distiller

International Nuclear Information System (INIS)

Costa, Gustavo Koury

1998-06-01

The need of water for human consumption in our region where there is a great storage of non saline sources has motivated the study of new desalination technologies. The present work introduces a water distiller whose main characteristic, in relation to other units, is the high production allied to a good efficiency. This equipment that promotes the reuse of the water condensation heat is then called Regenerative Distiller. A theoretical study of the thermodynamic process involved is made, resulting in a numeric model for the project of new units accordingly to the required demands. The theoretical results are also compared with experimental data obtained through the testing of prototype, built and put into operation by the FAE/DEN group of the Federal University of Pernambuco. (author)

Cell and biomolecule delivery for regenerative medicine

Science.gov (United States)

Smith, Ian O; Ma, Peter X

2010-01-01

Regenerative medicine is an exciting field that aims to create regenerative alternatives to harvest tissues for transplantation. In this approach, the delivery of cells and biological molecules plays a central role. The scaffold (synthetic temporary extracellular matrix) delivers cells to the regenerative site and provides three-dimensional environments for the cells. To fulfil these functions, we design biodegradable polymer scaffolds with structural features on multiple size scales. To enhance positive cell–material interactions, we design nano-sized structural features in the scaffolds to mimic the natural extracellular matrix. We also integrate micro-sized pore networks to facilitate mass transport and neo tissue regeneration. We also design novel polymer devices and self-assembled nanospheres for biomolecule delivery to recapitulate key events in developmental and wound healing processes. Herein, we present recent work in biomedical polymer synthesis, novel processing techniques, surface engineering and biologic delivery. Examples of enhanced cellular/tissue function and regenerative outcomes of these approaches are discussed to demonstrate the excitement of the biomimetic scaffold design and biologic delivery in regenerative medicine. PMID:27877317

Fuel processing for PEM fuel cells: transport and kinetic issues of system design

Science.gov (United States)

Zalc, J. M.; Löffler, D. G.

In light of the distribution and storage issues associated with hydrogen, efficient on-board fuel processing will be a significant factor in the implementation of PEM fuel cells for automotive applications. Here, we apply basic chemical engineering principles to gain insight into the factors that limit performance in each component of a fuel processor. A system consisting of a plate reactor steam reformer, water-gas shift unit, and preferential oxidation reactor is used as a case study. It is found that for a steam reformer based on catalyst-coated foils, mass transfer from the bulk gas to the catalyst surface is the limiting process. The water-gas shift reactor is expected to be the largest component of the fuel processor and is limited by intrinsic catalyst activity, while a successful preferential oxidation unit depends on strict temperature control in order to minimize parasitic hydrogen oxidation. This stepwise approach of sequentially eliminating rate-limiting processes can be used to identify possible means of performance enhancement in a broad range of applications.

Hydrogen production by a PEM electrolyser

International Nuclear Information System (INIS)

Aragón-González, G; León-Galicia, A; Camacho, J M Rivera; Uribe-Salazar, M; González-Huerta, R

2015-01-01

A PEM electrolyser for hydrogen production was evaluated. It was fed with water and a 400 mA, 3.5 V cc electrical power source. The electrolyser was built with two acrylic plates to form the anode and the cathode, two meshes to distribute the current, two seals, two gas diffusers and an assembly membrane-electrode. A small commercial neoprene sheet 1.7 mm thin was used to provide for the water deposit in order to avoid the machining of the structure. For the assembly of the proton interchange membrane a thin square 50 mm layer of Nafion 115 was used

Steam and partial oxidation reforming options for hydrogen production from fossil fuels for PEM fuel cells

OpenAIRE

Yousri M.A. Welaya; Mohamed M. El Gohary; Nader R. Ammar

2012-01-01

Proton exchange membrane fuel cell (PEM) generates electrical power from air and from hydrogen or hydrogen rich gas mixtures. Therefore, there is an increasing interest in converting current hydrocarbon based marine fuels such as natural gas, gasoline, and diesel into hydrogen rich gases acceptable to the PEM fuel cells on board ships. Using chemical flow sheeting software, the total system efficiency has been calculated. Natural gas appears to be the best fuel for hydrogen rich gas productio...

HyLIFT-0. 'Development and benchmarking of a 1st gen. HT-PEM/Li-lon hybrid motive power system for forklifts'. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Poulsen, Karsten (H2 Logic A/S, Herning (Denmark)); Elkjaer Toennesen, A. (Teknologisk Institut, AArhus (Denmark)); Torrendrup, C. (Lithium Balance A/S, Ishoej (Denmark)); Sangers, A. (Grundfos DK A/S, Bjerringbro (Denmark)); Junge, S. (Atlet Danmark A/S, Engesvang (Denmark))

2010-04-15

In the HyLIFT-0 project a HT-PEM/Li-Ion hybrid system for a forklift was developed and built. The system has been benchmark'et and tested both at H2 Logic, in a test bench at the Teknologisk Institut and by an end user, Grene A/S, who already has a hydrogen hybrid vehicle in service with LT-PEM system. The HT-PEM/Li-Ion system is based on a 1 kW SerEnergy fuel cell, with a 2.5 kWh Li-Ion battery pack and the newly developed BMS. Both Fuel cell systems were measured in the test bench at Teknologisk Institut. The conclusions are not fully accurate because there are many factors influencing such as the HT-PEM system not being fully optimized. The benchmark at Grene, showed that the heat up time is critical for the vehicle, but once it is in operation, there are no difference to the LT-PEM system, either in experienced performance or in user experience. The purpose of HyLIFT-0 project is met since the measurements and the benchmark has revealed the technology's advantages and disadvantages. Above all the conclusion is that HT-PEM/Li-Ion hybrid fuel cell system at the present stage of development is not a disruptive technology compared to known LT-PEM systems. There are numerous advantages of the system, but there are also some disadvantages, doing that, overall, it is not a usable technology in forklifts - it is especially the long start-up time of up to 45 minutes that is unacceptable for the fork lifter user; the user wants to have immediate maximum output and the battery cannot handle this during the time it lasts until the HT-PEM fuel cell is warm and producing power. The HT-PEM/Li-Ion system is relatively simple to build and it saves a number of components compared to the LT-PEM system, but the economic advantage of this is counterbalanced by the fuel cell being rather expensive and furthermore it has a relatively low efficiency. This will probably change over time when the technology completed development and volume increase. (LN)

INVESTIGATION OF PEM FUEL CELL FOR AUTOMOTIVE USE

Directory of Open Access Journals (Sweden)

A. K. M. Mohiuddin

2015-11-01

Full Text Available This paper provides a brief investigation on suitability of Proton-exchange  membrane fuel cells (PEMFCs as the source of power for transportation purposes. Hydrogen is an attractive alternative transportation fuel. It is the least polluting fuel that can be used in an internal combustion engine (ICE and it is widely available. If hydrogen is used in a fuel cell which converts the chemical energy of hydrogen into electricity, (NOx emissions are eliminated. The investigation was carried out on a  fuel cell car model by implementing polymer electrolyte membrane (PEM types of fuel cell as the source of power to propel the prototype car. This PEMFC has capability to propel the electric motor by converting chemical energy stored in hydrogen gas into useful electrical energy. PEM fuel cell alone is used as the power source for the electric motor without the aid of any other power source such as battery associated with it. Experimental investigations were carried out to investigate the characteristics of fuel cell used and the performance of the fuel cell car. Investigated papameters are the power it develops, voltage, current and speed it produces under different load conditions. KEYWORDS: fuel cell; automotive; proton exchange membrane; polymer electrolyte membrane; internal combustion engine

A computational model of a PEM fuel cell with finite vapor absorption rate

Energy Technology Data Exchange (ETDEWEB)

Vorobev, A.; Zikanov, O.; Shamim, T. [Department of Mechanical Engineering, University of Michigan-Dearborn, 48128-1491 Dearborn, MI (United States)

2007-03-30

The paper presents a new computational model of non-steady operation of a PEM fuel cell. The model is based on the macroscopic hydrodynamic approach and assumptions of low humidity operation and one-dimensionality of transport processes. Its novelty and advantage in comparison with similar existing models is that it takes into account the finite-time equilibration between vapor and membrane-phase liquid water within the catalyst layers. The phenomenon is described using an additional parameter with the physical meaning of the typical reciprocal time of the equilibration. A computational parametric study is conducted to identify the effect of the finite-time equilibration on steady-state and transient operation of a PEM fuel cell. (author)

Proceedings of the signature series event of the international society for cellular therapy: "Advancements in cellular therapies and regenerative medicine in digestive diseases," London, United Kingdom, May 3, 2017.

Science.gov (United States)

Ciccocioppo, Rachele; Dos Santos, Claudia C; Baumgart, Daniel C; Cangemi, Giuseppina C; Cardinale, Vincenzo; Ciacci, Carolina; De Coppi, Paolo; Haldar, Debashis; Klersy, Catherine; Nostro, M Cristina; Ott, Michael; Piemonti, Lorenzo; Tomei, Alice A; Uygun, Basak; Vetrano, Stefania; Orlando, Giuseppe

2018-03-01

A summary of the First Signature Series Event, "Advancements in Cellular Therapies and Regenerative Medicine for Digestive Diseases," held on May 3, 2017, in London, United Kingdom, is presented. Twelve speakers from three continents covered major topics in the areas of cellular therapy and regenerative medicine applied to liver and gastrointestinal medicine as well as to diabetes mellitus. Highlights from their presentations, together with an overview of the global impact of digestive diseases and a proposal for a shared online collection and data-monitoring platform tool, are included in this proceedings. Although growing evidence demonstrate the feasibility and safety of exploiting cell-based technologies for the treatment of digestive diseases, regulatory and methodological obstacles will need to be overcome before the successful implementation in the clinic of these novel attractive therapeutic strategies. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Microscale Regenerative Heat Exchanger

Science.gov (United States)

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

2006-01-01

The device described herein is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a "regenerator" in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle.

Review: Durability and degradation issues of PEM fuel cell components

NARCIS (Netherlands)

Bruijn, de F.A.; Dam, V.A.T.; Janssen, G.J.M.

2008-01-01

Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75 °C, using optimal stack and flow

Regenerative Braking System for Series Hybrid Electric City Bus

OpenAIRE

Zhang, Junzhi; Lu, Xin; Xue, Junliang; Li, Bos

2008-01-01

Regenerative Braking Systems (RBS) provide an efficient method to assist hybrid electric buses achieve better fuel economy while lowering exhaust emissions. This paper describes the design and testing of three regenerative braking systems, one of which is a series regenerative braking system and two of which are parallel regenerative braking systems. The existing friction based Adjustable Braking System (ABS) on the bus is integrated with each of the new braking systems in order to ensure bus...

New regenerative braking control strategy for rear-driven electrified minivans

International Nuclear Information System (INIS)

Junzhi, Zhang; Yutong, Li; Chen, Lv; Ye, Yuan

2014-01-01

Highlights: • A regenerative braking system is designed for a rear-driven electric minivan. • A new control strategy coordinating energy efficiency and braking feel is proposed. • The control strategy is verified by simulation and hardware-in-loop (HIL) tests. • The proposed control strategy offers higher regeneration efficiency. - Abstract: As of to 2012, minivan ownership stood at 20 million units in China, accounting for 16% of the passenger car market. In this article, comprehensive research is carried out on the design and control of a regenerative braking system for a rear-driven electrified minivan. For improving the regeneration efficiency by as much as possible, a new regenerative braking control strategy called “modified control strategy” is proposed. Additionally, a control strategy called “baseline control strategy” is introduced as a comparative control strategy. Simulations and hardware-in-loop (HIL) tests are carried out. The results of the simulations and the HIL tests show that the modified control strategy offers considerably higher regeneration efficiency than the baseline control strategy. In normal deceleration braking, the regeneration efficiency of the modified control strategy reaches 47%, 15% higher than that of the baseline control strategy. In addition, improvement in the fuel economy of electric vehicles operating on the ECE driving cycle and enhanced with the modified control strategy is greater than 10%, which is 3% higher than that with the baseline control strategy

Long-term stability of the Clear-PEM detector modules

International Nuclear Information System (INIS)

Amaral, Pedro; Bruyndonckx, Peter; Carrico, Bruno; Ferreira, Miguel; Luyten, Joan; Moura, Rui; Ortigao, Catarina; Rodrigues, Pedro; Silva, Jose C. da; Trindade, Andreia; Varela, Joao

2007-01-01

Experimental evaluation of the imaging system Clear-PEM for positron emission mammography, under development within the framework of the crystal clear collaboration at CERN, is presented in terms of its long-term stability. The detector modules and experimental setup are described. Time evolution results of signal yield, energy resolution, depth-of-interaction and inter-channel crosstalk for a reference detector module are reported

PEM fuel cells operated at 0% relative humidity in the temperature range of 23-120 oC

International Nuclear Information System (INIS)

Zhang, Jianlu; Tang, Yanghua; Song, Chaojie; Cheng, Xuan; Zhang, Jiujun; Wang, Haijiang

2007-01-01

Operation of a proton exchange membrane (PEM) fuel cell without external humidification (or 0% relative humidity, abbreviated as 0% RH) of the reactant gases is highly desirable, because it can eliminate the gas humidification system and thus decrease the complexity of the PEM fuel cell system and increase the system volume power density (W/l) and weight power density (W/kg). In this investigation, a PEM fuel cell was operated in the temperature range of 23-120 o C, in particular in a high temperature PEM fuel cell operation range of 80-120 o C, with dry reactant gases, and the cell performance was examined according to varying operation parameters. An ac impedance method was used to compare the performance at 0% RH with that at 100% RH; the results suggested that the limited proton transfer process to the Pt catalysts, mainly in the inonomer within the membrane electrode assembly (MEA) could be responsible for the performance drop. It was demonstrated that operating a fuel cell using a commercially available membrane (Nafion (registered) 112) is feasible under certain conditions without external humidification. However, the cell performance at 0% RH decreased with increasing operation temperature and reactant gas flow rate and decreasing operation pressure

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

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

Analysis of coupled proton and water transport in a PEM fuel cell using the binary friction membrane model

International Nuclear Information System (INIS)

Carnes, B.; Djilali, N.

2006-01-01

Transport of liquid water within a polymer electrolyte membrane (PEM) is critical to the operation of a PEM fuel cell, due to the strong dependence of the membrane transport coefficients on water content. In addition, enhanced predictive abilities are particularly significant in the context of passive air breathing fuel cell designs where lower water contents will prevail in the membrane. We investigate and analyze the numerical predictions of a recently proposed rational model for transport of protons and water in a PEM, when compared to a widely used empirical model. While the performance is similar for a saturated membrane, for PEMs with low water content, the difference in computed current density and membrane water crossover can be substantial. The effects of coupling partially saturated gas diffusion electrodes (GDLs) with the membrane are studied in both a 1D and 2D context. In addition, a simplified 1D analytical membrane water transport model is validated against the complete 1D model predictions. Our numerical results predict a higher current density and more uniform membrane hydration using a dry cathode instead of a dry anode, and illustrate that the strongest 2D effects are for water vapor transport

Design and experimental characterization of a 350 W High Temperature PEM fuel cell stack

Directory of Open Access Journals (Sweden)

Nicola Zuliani

2011-01-01

Full Text Available High Temperature Proton Exchange Membrane (HT PEM fuel cell based on polybenzimidazole (PBI polymer and phosphoric acid, can be operated at temperature between 120 °C and 180 °C. Reactants humidification is not required and CO content up to 2% in the fuel can be tolerated, affecting only marginally performance. This is what makes HT PEM very attractive, as low quality reformed hydrogen can be used and water management problems are avoided. Till nowadays, from experimental point of view, only few studies relate to the development and characterization of high temperature stacks. The aim of this work is to present the main design features and the performance curves of a 25 cells HT PEM stack based on PBI and phosphoric acid membranes. Performance curves refer to the stack operating with two type of fuels: pure hydrogen and a gas mixture simulating a typical steam reformer output. The stack voltage distribution analysis and the stack temperature distribution analysis suggest that cathode air could be used as coolant leading to a better thermal management. This could simplify stack design and system BOP, thus increasing system performance.

The regenerative medicine coalition. Interview with Frank-Roman Lauter.

Science.gov (United States)

Lauter, Frank-Roman

2012-11-01

Frank-Roman Lauter, Secretary General of the recently launched Regenerative Medicine Coalition, explains how the coalition was formed and what they hope to achieve. Frank-Roman Lauter has served as Secretary General of the Regenerative Medicine Coalition since 2012, and as Head of Business Development at Berlin-Brandenburg Center for Regenerative Therapies since 2007. Frank-Roman Lauter's interest is the organization of academic infrastructures to promote efficient translation of research findings into new therapies. He co-organizes joined strategy development for regenerative medicine clusters from seven European countries (FP7-EU Project) and has initiated cooperation between the California Institute for Regenerative Medicine and the German Federal Ministry for Education & Research, resulting in a joined funding program. Recently, he cofounded the international consortium of Regenerative Medicine translational centers (RMC; www.the-rmc.org ). Trained as a molecular biologist at the Max-Planck Institute in Berlin-Dahlem and at Stanford, he has 16 years of experience as an entrepreneur and life science manager in Germany and the USA.

Performance of a PEM water electrolyser using a TaC-supported iridium oxide electrocatalyst

DEFF Research Database (Denmark)

Polonský, J.; Mazúr, P.; Paidar, M.

2014-01-01

by dispersing the precious metal compound onto a catalyst support. Electrocatalysts with 50, 70 and 90 wt.% of IrO2 on a TaC support were tested in a laboratory PEM water electrolyser and compared with pure IrO2. The temperature was set at 90, 110, 120 and 130 °C respectively and the cell voltage was varied......Polymer electrolyte membrane (PEM) water electrolysis is an attractive way of producing carbon-free hydrogen. One of the drawbacks of this method is the need for precious metal-based electrocatalysts. This calls for a highly efficient utilization of the precious metal, which can be obtained...

Modelling membrane hydration and water balance of a pem fuel cell

DEFF Research Database (Denmark)

Liso, Vincenzo; Nielsen, Mads Pagh

2015-01-01

Polymer electrolyte membrane (PEM) fuel cells requires an appropriate hydration in order to ensure high efficiency and long durability. As water is essential for promoting proton conductivity in the membrane, it is important to control membrane water hydration to avoid flooding. In this study we...

Regenerative Endodontics: Barriers and Strategies for Clinical Translation

OpenAIRE

Kim, Sahng G.; Zhou, Jian; Ye, Ling; Cho, Shoko; Suzuki, Takahiro; Fu, Susan Y.; Yang, Rujing; Zhou, Xuedong; Mao, Jeremy J.

2012-01-01

Despite a great deal of enthusiasm and effort, regenerative endodontics has encountered substantial challenges towards clinical translation. Recent adoption by the American Dental Association (ADA) of evoked pulp bleeding in immature permanent teeth is an important step for regenerative endodontics. However, there is no regenerative therapy for the majority of endodontic diseases. Simple recapitulation of cell therapy and tissue engineering strategies that are under development for other orga...

Controllable clock circuit design in PEM system

International Nuclear Information System (INIS)

Sun Yunhua; Wang Peihua; Hu Tingting; Feng Baotong; Shuai Lei; Huang Huan; Wei Shujun; Li Ke; Zhao Jingwei; Wei Long

2011-01-01

A high-precision synchronized clock circuit design will be presented, which can supply steady, reliable and anti-jamming clock signal for the data acquirement (DAQ) system of Positron Emission Mammography (PEM). This circuit design is based on the Single-Chip Microcomputer and high-precision clock chip, and can achieve multiple controllable clock signals. The jamming between the clock signals can be reduced greatly with the differential transmission. Meanwhile, the adoption of CAN bus control in the clock circuit can prompt the clock signals to be transmitted or masked simultaneously when needed. (authors)

Controllable clock circuit design in PEM system

International Nuclear Information System (INIS)

Sun Yunhua; Wang Peilin; Hu Tingting; Feng Baotong; Shuai Lei; Huang Huan; Wei Shujun; Li Ke; Zhao Jingwei; Wei Long

2010-01-01

A high-precision synchronized clock circuit design will be presented, which can supply steady, reliable and anti-jamming clock signal for the data acquirement (DAQ) system of Positron Emission Mammography (PEM). This circuit design is based on the Single-Chip Microcomputer and high-precision clock chip, and can achieve multiple controllable clock signals. The jamming between the clock signals can be reduced greatly with the differential transmission. Meanwhile, the adoption of CAN bus control in the clock circuit can prompt the clock signals to be transmitted or masked simultaneously when needed. (authors)

Regenerative medicine applications in combat casualty care.

Science.gov (United States)

Fleming, Mark E; Bharmal, Husain; Valerio, Ian

2014-03-01

The purpose of this report is to describe regenerative medicine applications in the management of complex injuries sustained by service members injured in support of the wars in Afghanistan and Iraq. Improvements in body armor, resuscitative techniques and faster transport have translated into increased patient survivability and more complex wounds. Combat-related blast injuries have resulted in multiple extremity injuries, significant tissue loss and amputations. Due to the limited availability and morbidity associated with autologous tissue donor sites, the introduction of regenerative medicine has been critical in managing war extremity injuries with composite massive tissue loss. Through case reports and clinical images, this report reviews the application of regenerative medicine modalities employed to manage combat-related injuries. It illustrates that the novel use of hybrid reconstructions combining traditional and regenerative medicine approaches are an effective tool in managing wounds. Lessons learned can be adapted to civilian care.

Design of An Energy Efficient Hydraulic Regenerative circuit

Science.gov (United States)

Ramesh, S.; Ashok, S. Denis; Nagaraj, Shanmukha; Adithyakumar, C. R.; Reddy, M. Lohith Kumar; Naulakha, Niranjan Kumar

2018-02-01

Increasing cost and power demand, leads to evaluation of new method to increase through productivity and help to solve the power demands. Many researchers have break through to increase the efficiency of a hydraulic power pack, one of the promising methods is the concept of regenerative. The objective of this research work is to increase the efficiency of a hydraulic circuit by introducing a concept of regenerative circuit. A Regenerative circuit is a system that is used to speed up the extension stroke of the double acting single rod hydraulic cylinder. The output is connected to the input in the directional control value. By this concept, increase in velocity of the piston and decrease the cycle time. For the research, a basic hydraulic circuit and a regenerative circuit are designated and compared both with their results. The analysis was based on their time taken for extension and retraction of the piston. From the detailed analysis of both the hydraulic circuits, it is found that the efficiency by introducing hydraulic regenerative circuit increased by is 5.3%. The obtained results conclude that, implementing hydraulic regenerative circuit in a hydraulic power pack decreases power consumption, reduces cycle time and increases productivity in a longer run.

Use of biogas in PEM fuel cells; Einsatz von Biogas in PEM-Brennstoffzellen

Energy Technology Data Exchange (ETDEWEB)

Scholz, Volkhard; Schmersahl, Ralf; Ellner, Janine (comps.)

2009-06-15

This research project was dedicated to two problems: 1. What demands must biogas meet in order to conform to the specifications of PEM fuel cell systems and permit safe operation? 2. How must a fuel cell system be designed and operated in order to be well-adapted to the special features of biogas as opposed to natural gas? For this purpose biogas samples were taken from laboratory-scale and commercial plants and analysed by gas chromatography using various substrates and methods. By combining this with the use of a mass spectroscopy detector (GC-MS system) it was possible to perform a qualitative and quantitative analysis of sulphurious trace gases in the biogas which might cause damage to the fuel cell system. Investigations were performed on an experimental reformer using either modelled or native biogas of different compositions, the intent being to obtain information for the design of the individual process stages. The two operating parameters steam-methane ratio (or S/C ratio) and reforming temperature were varied to optimise parameter settings in terms of energy efficiency. By linking the reformer to a 500 W fuel cell it was possible confirm the suitability of the reformed biogas for use in fuel cells. [German] In diesm Forschungsvorhaben werden zwei Fragestellungen bearbeitet: 1. Welche Anforderungen ergeben sich an das Biogas, um den Spezifikationen von PEM-Brennstoffzellensystemen zu genuegen und eine sicheren Betrieb zu ermoeglichen? 2. Wie muss das Brennstoffzellensystem ausgelegt und gefuehrt werden, um den Besonderheiten von Biogas im Vergleich zu Erdgas Rechnung zu tragen? Dazu wurden Biogasproben aus Labor- und Praxisanlagen unter Beruecksichtigung unterschiedlicher Substrate und Verfahren gaschromatisch analysiert. Die Kopplung mit einem massenspektroskopischen Detektor (GC-MS System) ermoeglicht dabei die Qualifizierung und Quantifizierung der vorhandenen schwefelhaltigen Spurengase, die eine Schaedigung von Brennstoffzellenanlagen verursachen. Die

Development of Novel PEM Membrane and Multiphase CD Modeling of PEM Fuel Cell

Energy Technology Data Exchange (ETDEWEB)

K. J. Berry; Susanta Das

2009-12-30

To understand heat and water management phenomena better within an operational proton exchange membrane fuel cell's (PEMFC) conditions, a three-dimensional, two-phase computational fluid dynamic (CFD) flow model has been developed and simulated for a complete PEMFC. Both liquid and gas phases are considered in the model by taking into account the gas flow, diffusion, charge transfer, change of phase, electro-osmosis, and electrochemical reactions to understand the overall dynamic behaviors of species within an operating PEMFC. The CFD model is solved numerically under different parametric conditions in terms of water management issues in order to improve cell performance. The results obtained from the CFD two-phase flow model simulations show improvement in cell performance as well as water management under PEMFCs operational conditions as compared to the results of a single phase flow model available in the literature. The quantitative information obtained from the two-phase model simulation results helped to develop a CFD control algorithm for low temperature PEM fuel cell stacks which opens up a route in designing improvement of PEMFC for better operational efficiency and performance. To understand heat and water management phenomena better within an operational proton exchange membrane fuel cell's (PEMFC) conditions, a three-dimensional, two-phase computational fluid dynamic (CFD) flow model has been developed and simulated for a complete PEMFC. Both liquid and gas phases are considered in the model by taking into account the gas flow, diffusion, charge transfer, change of phase, electro-osmosis, and electrochemical reactions to understand the overall dynamic behaviors of species within an operating PEMFC. The CFD model is solved numerically under different parametric conditions in terms of water management issues in order to improve cell performance. The results obtained from the CFD two-phase flow model simulations show improvement in cell

Metallurgical investigation of cracking of the isolation valve downstream piping of regenerative heat exchanger at beaver valley unit 1 station

International Nuclear Information System (INIS)

Rao, G.V.

1998-01-01

A metallurgical investigation was conducted to establish the mechanism and cause of cracking in the regenerative heat exchanger piping at Beaver Valley Unit 1 PWR station in the USA. The investigation, which was centered on an eight inch long pipe section containing the cracking included surface examinations, metallographic and fractographic examinations, and chemistry evaluations. The results of the examinations showed that there were two types of pipe degradation mechanisms that affected the type 304 stainless schedule 40 piping. These consisted of localized corrosive attack on the OD surface due to the presence of chlorides, sulphates and phosphates, and transgranular stress corrosion cracking in the pipe wall due to the presence of chloride contaminants. The overall results of the investigation showed that the introduction of contaminants from external sources other than pipe insulation was the cause of heat exchanger pipe cracking. (author)

Patriot Script 1.0.13 User Guide for PEM 1.3.2

Energy Technology Data Exchange (ETDEWEB)

Cleland, Timothy James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kubicek, Deborah Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stroud, Phillip David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cuellar-Hengartner, Leticia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mathis, Mark [Descartes Labs, Inc., Los Alamos, NM (United States)

2015-11-02

This document provides an updated user guide for Patriot Script Version 1.0.13, for release with PEM 1.3.1 (LAUR-1422817) that adds description and instructions for the new excursion capability (see section 4.5.1).

CFD modelling of cooling channel geometry of PEM fuel cell for ...

African Journals Online (AJOL)

In this study, a numerical investigation was carried out to deter mine the impact of cooling channel geometry in combination with temperature dependent operating parameters on thermal management and overall performance of a PEM fuel cell system. The evaluation is performed using a computational fluid dynamics ...

Development of a 400 W High Temperature PEM Fuel Cell Power Pack

DEFF Research Database (Denmark)

Schaltz, Erik; Jespersen, Jesper Lebæk; Rasmussen, Peter Omand

2006-01-01

reformer design because CO removal is not needed. A fuel like methanol would be a preferable choice for reforming when using HTPEM fuel cells because of its high energy density and low reforming temperatures. The thermal integration and use of HTPEM fuel cells with methanol reformers show promising results......When using pressurized hydrogen to fuel a fuel cell, much space is needed for fuel storage. This is undesirable especially with mobile or portable fuel cell systems, where refuelling also often is inconvenient. Using a reformed liquid carbonhydrate can reduce this fuel volume considerably. Nafion...... based low temperature PEM (LTPEM) fuel cells are very intolerant to reformate gas because of the presence of CO. PBI based high temperature PEM (HTPEM) fuel cells can operate stable at much higher CO concentrations. This makes the HTPEM very suitable for applications using a reformer, and could simplify...

Regeneration of CO poisoned PEM fuel cells by periodic pulsed oxidation

International Nuclear Information System (INIS)

Adams, W.A.; Blair, J.; Bullock, K.R.; Gardner, C.L.

2004-01-01

CO poisoning is a major issue when reformate is used as a fuel in PEM fuel cells. Normally it is necessary to reduce the CO to very low levels (∼5 ppm) and CO tolerant catalysts, such as Pt-Ru, are often employed. As an alternative approach, we have studied the use of pulsed oxidation for the regeneration of CO poisoned cells. Results are presented for the regeneration of Pt and Pt-Ru anodes in a PEM fuel cell fed with CO concentrations as high as 10,000 ppm. The results show periodic removal of CO from the catalyst surface by pulsed oxidation can increase the average cell potential and increase overall efficiency. A method for enhancing the performance of a fuel cell stack using a microprocessor-based Fuel Cell Health Manager (FCHM) has been developed. The results of a cost/benefit analysis for the use of a FCHM on a 4 kW residential fuel cell system are presented. (author)

Aarhus Regenerative Orthopaedics Symposium (AROS)

DEFF Research Database (Denmark)

Foldager, Casper B.; Bendtsen, Michael; Berg, Lise C.

2016-01-01

to musculoskeletal pain and disability. The Aarhus Regenerative Orthopaedics Symposium (AROS) 2015 was motivated by the need to address regenerative challenges in an ageing population by engaging clinicians, basic scientists, and engineers. In this position paper, we review our contemporary understanding of societal......, patient-related, and basic science-related challenges in order to provide a reasoned roadmap for the future to deal with this compelling and urgent healthcare problem. © 2017 The Author(s). Published by Taylor & Francis on behalf of the Nordic Orthopedic Federation....

A survey of dental residents' expectations for regenerative endodontics.

Science.gov (United States)

Manguno, Christine; Murray, Peter E; Howard, Cameron; Madras, Jonathan; Mangan, Stephen; Namerow, Kenneth N

2012-02-01

The objective was to survey a group of dental residents regarding their expectations for using regenerative endodontic procedures as part of future dental treatments. After institutional review board approval, the opinions of 32 dentists who were having postgraduate residency training to become specialists in a dental school were surveyed. The survey had 40 questions about professional status, ethical beliefs, judgment, and clinical practice. It was found that 83.9% of dentists had no continuing education or training in stem cells or regenerative endodontic procedures. Results showed that 96.8% of dentists are willing to receive training to be able to provide regenerative endodontic procedures for their patients. Of the total group, 49.1% of dentists already use membranes, scaffolds, or bioactive materials to provide dental treatment. It was determined that 47.3% of dentists agree that the costs of regenerative procedures should be comparable with current treatments. It was also found that 55.1% of dentists were unsure whether regenerative procedures would be successful. Dentists are supportive of using regenerative endodontic procedures in their dental practice, and they are willing to undergo extra training and to buy new technology to provide new procedures. Nevertheless, dentists also need more evidence for the effectiveness and safety of regenerative treatments before they will be recommended for most patients. Copyright © 2012. Published by Elsevier Inc.

Characterization and quality control of avalanche photodiode arrays for the Clear-PEM detector modules

International Nuclear Information System (INIS)

Abreu, Conceicao; Amaral, Pedro; Carrico, Bruno; Ferreira, Miguel; Luyten, Joan; Moura, Rui; Ortigao, Catarina; Rato, Pedro; Varela, Joao

2007-01-01

Clear-PEM is a Positron Emission Mammography (PEM) prototype being developed in the framework of the Crystal Clear Collaboration at CERN. This device is a dedicated PET camera for mammography, based on LYSO:Ce scintillator crystals, Avalanche PhotoDiodes (APD) and a fast, low-noise electronics readout system, designed to examine both the breast and the axillary lymph node areas, and aiming at the detection of tumors down to 2 mm in diameter. The prototype has two planar detector heads, each composed of 96 detector modules. The Clear-PEM detector module is composed of a matrix of 32 identical 2x2x20 mm 3 LYSO:Ce crystals read at both ends by Hamamatsu S8550 APD arrays (4x8) for Depth-of-Interaction (DoI) capability. The APD arrays were characterized by the measurement of gain and dark current as a function of bias voltage, under controlled temperature conditions. Two independent setups were used. The full set of 398 APD arrays followed a well-defined quality control (QC) protocol, aiming at the rejection of arrays not complying within defined specifications. From a total of 398 arrays, only 2 (0.5%) were rejected, reassuring the trust in these detectors for prototype assembly and future developments

The effect of material properties on the performance of a new geometry PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Khazaee, Iman [Islamic Azad University, Department of Mechanical Engineering, Torbat-e-jam Branch, Torbat-e-jam (Iran, Islamic Republic of); Ghazikhani, Mohsen [Ferdowsi University of Mashhad, Department of Mechanical Engineering, Faculty of Engineering, Mashhad (Iran, Islamic Republic of)

2012-05-15

In this paper a computational dynamics model for duct-shaped geometry proton exchange membrane (PEM) fuel cell was used to investigate the effect of changing gas diffusion layer and membrane properties on the performances, current density and gas concentration. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the 2-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC that cannot be investigated experimentally. The results show that by increasing the thickness and decreasing the porosity of GDL the performance of the cell enhances that it is different with planner PEM fuel cell. Also the results show that by increasing the thermal conductivity of the GDL and membrane, the overall cell performance increases. (orig.)

Platelet-rich fibrin: a boon in regenerative endodontics.

Science.gov (United States)

Rebentish, Priyanka D; Umashetty, Girish; Kaur, Harpreet; Doizode, Trupthi; Kaslekar, Mithun; Chowdhury, Shouvik

2016-12-01

Research into regenerative dentistry has contributed momentum to the field of molecular biology. Periapical surgery aims at removing periapical pathology to achieve complete wound healing and regeneration of bone and periodontal tissue. Regenerative endodontic procedures are widely being added to the current armamentarium of pulp therapy procedures. The regenerative potential of platelets has been deliberated. Platelet-rich fibrin (PRF) is a wonderful tissue-engineering product and has recently gained much popularity due its promising results in wound healing bone induction. The features of this product are an attribute of platelets which, after cellular interactions, release growth factors and have shown application in diverse disciplines of dentistry. This paper is intended to shed light onto the various prospects of PRF and to provide clinical insight into regenerative endodontic therapy.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

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

Steam and partial oxidation reforming options for hydrogen production from fossil fuels for PEM fuel cells

Directory of Open Access Journals (Sweden)

Yousri M.A. Welaya

2012-06-01

Full Text Available Proton exchange membrane fuel cell (PEM generates electrical power from air and from hydrogen or hydrogen rich gas mixtures. Therefore, there is an increasing interest in converting current hydrocarbon based marine fuels such as natural gas, gasoline, and diesel into hydrogen rich gases acceptable to the PEM fuel cells on board ships. Using chemical flow sheeting software, the total system efficiency has been calculated. Natural gas appears to be the best fuel for hydrogen rich gas production due to its favorable composition of lower molecular weight compounds. This paper presents a study for a 250 kW net electrical power PEM fuel cell system utilizing a partial oxidation in one case study and steam reformers in the second. This study has shown that steam-reforming process is the most competitive fuel processing option in terms of fuel processing efficiency. Partial oxidation process has proved to posses the lowest fuel processing efficiency. Among the options studied, the highest fuel processing efficiency is achieved with natural gas steam reforming system.

Regenerative Rehabilitation: Combining Stem Cell Therapies and Activity-Dependent Stimulation.

Science.gov (United States)

Moritz, Chet T; Ambrosio, Fabrisia

2017-07-01

The number of clinical trials in regenerative medicine is burgeoning, and stem cell/tissue engineering technologies hold the possibility of becoming the standard of care for a multitude of diseases and injuries. Advances in regenerative biology reveal novel molecular and cellular targets, with potential to optimize tissue healing and functional recovery, thereby refining rehabilitation clinical practice. The purpose of this review is to (1) highlight the potential for synergy between the fields of regenerative medicine and rehabilitation, a convergence of disciplines known as regenerative rehabilitation; (2) provide translational examples of regenerative rehabilitation within the context of neuromuscular injuries and diseases; and (3) offer recommendations for ways to leverage activity dependence via combined therapy and technology, with the goal of enhancing long-term recovery. The potential clinical benefits of regenerative rehabilitation will likely become a critical aspect in the standard of care for many neurological and musculoskeletal disorders.

Silicon carbide-silicon as a support material for oxygen evolution reaction in PEM steam electrolysers

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

cells. In the present work a commercial SiC-Si, produced by the Acheson process, with a fraction of free silicon around 20% wt. was investigated as a catalyst support for anode electrocatalyst in PEM steam electrolysers. This electrocatalyst system was characterized using several techniques such as XRD......, cyclic voltammetry, SEM, EDX and steady state electrochemical polarisation in a working PEM steam electrolyser. Several SiC-Si-IrO2 electrodes have been prepared and tested. The iridium oxide content at the electrode active layer varied from x=0.2 to x=1, corresponding to the general formula (1-x...... for phosphoric acid doped membrane steam electrolysers....

Modeling a Distributed Power Flow Controller with a PEM Fuel Cell for Power Quality Improvement

Directory of Open Access Journals (Sweden)

J. Chakravorty

2018-02-01

Full Text Available Electrical power demand is increasing at a relatively fast rate over the last years. Because of this increasing demand the power system is becoming very complex. Both electric utilities and end users of electric power are becoming increasingly concerned about power quality. This paper presents a new concept of distributed power flow controller (DPFC, which has been implemented with a proton exchange membrane (PEM fuel cell. In this paper, a PEM fuel cell has been simulated in Simulink/MATLAB and then has been used in the proposed DPFC model. The new proposed DPFC model has been tested on a IEEE 30 bus system.

Modeling two-phase flow in PEM fuel cell channels

Energy Technology Data Exchange (ETDEWEB)

Wang, Yun; Basu, Suman; Wang, Chao-Yang [Electrochemical Engine Center (ECEC), and Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

2008-05-01

This paper is concerned with the simultaneous flow of liquid water and gaseous reactants in mini-channels of a proton exchange membrane (PEM) fuel cell. Envisaging the mini-channels as structured and ordered porous media, we develop a continuum model of two-phase channel flow based on two-phase Darcy's law and the M{sup 2} formalism, which allow estimate of the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction. Analytical solutions of liquid water saturation and species concentrations along the channel are derived to explore the dependences of these physical variables vital to cell performance on operating parameters such as flow stoichiometric ratio and relative humility. The two-phase channel model is further implemented for three-dimensional numerical simulations of two-phase, multi-component transport in a single fuel-cell channel. Three issues critical to optimizing channel design and mitigating channel flooding in PEM fuel cells are fully discussed: liquid water buildup towards the fuel cell outlet, saturation spike in the vicinity of flow cross-sectional heterogeneity, and two-phase pressure drop. Both the two-phase model and analytical solutions presented in this paper may be applicable to more general two-phase flow phenomena through mini- and micro-channels. (author)

An Open-Source Toolbox for PEM Fuel Cell Simulation

Directory of Open Access Journals (Sweden)

Jean-Paul Kone

2018-05-01

Full Text Available In this paper, an open-source toolbox that can be used to accurately predict the distribution of the major physical quantities that are transported within a proton exchange membrane (PEM fuel cell is presented. The toolbox has been developed using the Open Source Field Operation and Manipulation (OpenFOAM platform, which is an open-source computational fluid dynamics (CFD code. The base case results for the distribution of velocity, pressure, chemical species, Nernst potential, current density, and temperature are as expected. The plotted polarization curve was compared to the results from a numerical model and experimental data taken from the literature. The conducted simulations have generated a significant amount of data and information about the transport processes that are involved in the operation of a PEM fuel cell. The key role played by the concentration constant in shaping the cell polarization curve has been explored. The development of the present toolbox is in line with the objectives outlined in the International Energy Agency (IEA, Paris, France Advanced Fuel Cell Annex 37 that is devoted to developing open-source computational tools to facilitate fuel cell technologies. The work therefore serves as a basis for devising additional features that are not always feasible with a commercial code.

Overcoming immunological barriers in regenerative medicine.

Science.gov (United States)

Zakrzewski, Johannes L; van den Brink, Marcel R M; Hubbell, Jeffrey A

2014-08-01

Regenerative therapies that use allogeneic cells are likely to encounter immunological barriers similar to those that occur with transplantation of solid organs and allogeneic hematopoietic stem cells (HSCs). Decades of experience in clinical transplantation hold valuable lessons for regenerative medicine, offering approaches for developing tolerance-induction treatments relevant to cell therapies. Outside the field of solid-organ and allogeneic HSC transplantation, new strategies are emerging for controlling the immune response, such as methods based on biomaterials or mimicry of antigen-specific peripheral tolerance. Novel biomaterials can alter the behavior of cells in tissue-engineered constructs and can blunt host immune responses to cells and biomaterial scaffolds. Approaches to suppress autoreactive immune cells may also be useful in regenerative medicine. The most innovative solutions will be developed through closer collaboration among stem cell biologists, transplantation immunologists and materials scientists.

Regenerative endodontics--Creating new horizons.

Science.gov (United States)

Dhillon, Harnoor; Kaushik, Mamta; Sharma, Roshni

2016-05-01

Trauma to the dental pulp, physical or microbiologic, can lead to inflammation of the pulp followed by necrosis. The current treatment modality for such cases is non-surgical root canal treatment. The damaged tissue is extirpated and the root canal system prepared. It is then obturated with an inert material such a gutta percha. In spite of advances in techniques and materials, 10%-15% of the cases may end in failure of treatment. Regenerative endodontics combines principles of endodontics, cell biology, and tissue engineering to provide an ideal treatment for inflamed and necrotic pulp. It utilizes mesenchymal stem cells, growth factors, and organ tissue culture to provide treatment. Potential treatment modalities include induction of blood clot for pulp revascularization, scaffold aided regeneration, and pulp implantation. Although in its infancy, successful treatment of damaged pulp tissue has been performed using principles of regenerative endodontics. This field is dynamic and exciting with the ability to shape the future of endodontics. This article highlights the fundamental concepts, protocol for treatment, and possible avenues for research in regenerative endodontics. © 2015 Wiley Periodicals, Inc.

Test system design for Hardware-in-Loop evaluation of PEM fuel cells and auxiliaries

Energy Technology Data Exchange (ETDEWEB)

Randolf, Guenter; Moore, Robert M. [Hawaii Natural Energy Institute, University of Hawaii, Honolulu, HI (United States)

2006-07-14

In order to evaluate the dynamic behavior of proton exchange membrane (PEM) fuel cells and their auxiliaries, the dynamic capability of the test system must exceed the dynamics of the fastest component within the fuel cell or auxiliary component under test. This criterion is even more critical when a simulated component of the fuel cell system (e.g., the fuel cell stack) is replaced by hardware and Hardware-in-Loop (HiL) methodology is employed. This paper describes the design of a very fast dynamic test system for fuel cell transient research and HiL evaluation. The integration of the real time target (which runs the simulation), the test stand PC (that controls the operation of the test stand), and the programmable logic controller (PLC), for safety and low-level control tasks, into one single integrated unit is successfully completed. (author)

The dissolution kinetics of magnetite under regenerative conditions

International Nuclear Information System (INIS)

Ranganathan, S.

2004-01-01

Dissolution studies of magnetite were carried out under regenerative conditions in dilute chemical decontamination formulations. During regeneration of the formulation, the H + from the strong acid cation exchange resin gets released and the metal is absorbed on the resin. The efficiency of the regenerative process depends on the stability constants of the complexes involved and the selectivity on the ion exchange column. The regenerative condition helps to maintain a constant chelating agent concentration and pH during the dissolution experiment. Such a condition is ideal for obtaining data on the dissolution behaviour of the corrosion products with special application to actual reactor decontamination. The ethylenediaminetetraacetic acid (EDTA) based formulation used was found to be ineffective due to the high stability constant of Fe(III)-EDTA complex, which is not easily cleaved by the cation exchange resin. Hence, knowledge of the kinetics of magnetite dissolution under regenerative condition is of primary importance. The 2,6-pyridinedicarboxylic acid formulation is found to be better for the dissolution of Fe 3 O 4 in both static and regenerative modes in the presence of reductants than nitrilotriacetic acid and EDTA. (orig.)

The dissolution kinetics of magnetite under regenerative conditions

Energy Technology Data Exchange (ETDEWEB)

Ranganathan, S. [New Brunswick Univ., Frederiction (Canada). Dept. of Chemical Engineering; Raghavan, P.S.; Gopalan, R.; Srinivasan, M.P.; Narasimhan, S.V. [Water and Steam Chemistry Lab. of Bhabha Atomic Research Centre (BARC) (India)

2004-07-01

Dissolution studies of magnetite were carried out under regenerative conditions in dilute chemical decontamination formulations. During regeneration of the formulation, the H{sup +} from the strong acid cation exchange resin gets released and the metal is absorbed on the resin. The efficiency of the regenerative process depends on the stability constants of the complexes involved and the selectivity on the ion exchange column. The regenerative condition helps to maintain a constant chelating agent concentration and pH during the dissolution experiment. Such a condition is ideal for obtaining data on the dissolution behaviour of the corrosion products with special application to actual reactor decontamination. The ethylenediaminetetraacetic acid (EDTA) based formulation used was found to be ineffective due to the high stability constant of Fe(III)-EDTA complex, which is not easily cleaved by the cation exchange resin. Hence, knowledge of the kinetics of magnetite dissolution under regenerative condition is of primary importance. The 2,6-pyridinedicarboxylic acid formulation is found to be better for the dissolution of Fe{sub 3}O{sub 4} in both static and regenerative modes in the presence of reductants than nitrilotriacetic acid and EDTA. (orig.)

Development and Study of Tantalum and Niobium Carbides as Electrocatalyst Supports for the Oxygen Electrode for PEM Water Electrolysis at Elevated Temperatures

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Prag, Carsten Brorson

2013-01-01

Polymer electrolyte membrane (PEM) water electrolysis is a prospective method of producing hydrogen. We focused on one of its issues – the lack of a suitable support material for the anode electrocatalyst. TaC and NbC were studied as possible electrocatalyst supports for the PEM water electrolysis...

Regenerative Stem Cell Therapy for Breast Cancer Bone Metastasis

Science.gov (United States)

2015-11-01

1 AD_________________ Award Number: W81XWH-11-1-0593 TITLE: Regenerative Stem Cell Therapy for Breast Cancer Bone Metastasis PRINCIPAL...3. DATES COVERED (From - To) 09/15/2011 - 08/14/2015 4. TITLE AND SUBTITLE Regenerative Stem Cell Therapy for Breast Cancer Bone Metastasis 5a...4 Title of the Grant: Regenerative Stem Cell Therapy for Breast Cancer Bone Metastasis Award number: W81XWH-11-1-0593 Principal Investigator

Regenerative Hydride Heat Pump

Science.gov (United States)

Jones, Jack A.

1992-01-01

Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

Combined hydraulic and regenerative braking system

Science.gov (United States)

Venkataperumal, R.R.; Mericle, G.E.

1979-08-09

A combined hydraulic and regenerative braking system and method for an electric vehicle is disclosed. The braking system is responsive to the applied hydraulic pressure in a brake line to control the braking of the vehicle to be completely hydraulic up to a first level of brake line pressure, to be partially hydraulic at a constant braking force and partially regenerative at a linearly increasing braking force from the first level of applied brake line pressure to a higher second level of brake line pressure, to be partially hydraulic at a linearly increasing braking force and partially regenerative at a linearly decreasing braking force from the second level of applied line pressure to a third and higher level of applied line pressure, and to be completely hydraulic at a linearly increasing braking force from the third level to all higher applied levels of line pressure.

Proton tunneling-induced bistability, oscillations and enhanced performance of PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Katsaounis, A.; Balomenou, S.; Tsiplakides, D.; Brosda, S.; Vayenas, C.G. [Department of Chemical Engineering, University of Patras, Patras GR 26504 (Greece); Neophytides, S. [Institute of Chemical Engineering and High Temperature Chemical Processes, FORTH, 26500 Patras (Greece)

2005-03-25

Proton migration through hydrated Nafion membranes in polymer electrolyte membrane (PEM) fuel cells occurs both in the aqueous phase of the membrane and on the sulfonate groups on the surface of the membrane pores. Here we show using D{sub 2} and H{sub 2} fuel and basic quantum mechanical equations that this surface proton migration is largely due to proton tunneling between adjacent sulfonate groups, leading to an exponential variation of Nafion conductivity with cell potential. This amphibious mode of proton migration, particle-like in the aqueous phase and wave-like in the narrow pores, is shown to be the major cause of cell overpotential, bistability and oscillations of state-of-the-art PEM fuel cells operating on H{sub 2}, reformate or methanol fuel. We also show that this phenomenon can be exploited via introduction of a third auxiliary electrode to independently control the anode-cathode potential difference and dramatically enhance fuel cell power output even in absence of noble metals at the anode.

Coupling of a 2.5 kW steam reformer with a 1 kW el PEM fuel cell

Science.gov (United States)

Mathiak, J.; Heinzel, A.; Roes, J.; Kalk, Th.; Kraus, H.; Brandt, H.

The University of Duisburg-Essen has developed a compact multi-fuel steam reformer suitable for natural gas, propane and butane. This steam reformer was combined with a polymer electrolyte membrane fuel cell (PEM FC) and a system test of the process chain was performed. The fuel processor comprises a prereformer step, a primary reformer, water gas shift reactors, a steam generator, internal heat exchangers in order to achieve an optimised heat integration and an external burner for heat supply as well as a preferential oxidation step (PROX) as CO purification. The fuel processor is designed to deliver a thermal hydrogen power output from 500 W to 2.5 kW. The PEM fuel cell stack provides about 1 kW electrical power. In the following paper experimental results of measurements of the single components PEM fuel cell and fuel processor as well as results of the coupling of both to form a process chain are presented.

A reversible electrolyzer-fuel cell system based on PEM technology

International Nuclear Information System (INIS)

Grigoriev, S.A.; Millet, P.; Fateev, V.N.

2009-01-01

'Full text': A reversible electrolyzer-fuel cell is an electrochemical system which can be alternatively operated in water electrolysis or H 2 /O 2 (air) fuel cell modes. Whereas proton-exchange membrane (PEM) water electrolysis and PEM fuel cell technologies are individually well-established, it is still a very challenging task to develop efficient reversible systems which can maintain interesting electrochemical performances during a significant number of cycles. Results reported in this communication are related to R and D on bi-functional catalysts, electrocatalytic layers, gas diffusion layers/current collectors and reversible PEM stack design. Electrodes which do not change their redox status when the operation mode of the cell is switched from electrolysis to fuel cell are more specifically considered. In particular, it is shown that, when the anode is composed of Pt-Ir layers (ca. 0.5/0.5 wt. ratio), best electrochemical performances are obtained (for both for water and hydrogen oxidation reactions) when an Ir layer is placed face-to-face with the membrane. Cathodic electrocatalytic layers made of Pt/C were prepared and optimized by adding PTFE to obtain the required hydrophobic-hydrophilic properties for effective oxygen and protons electro-reduction. Gas diffusion electrodes made of porous carbon materials and bi-porous titanium sheets with appropriate water management properties have also been developed. A two-cell stack with 250 cm 2 active area electrodes has been assembled using the optimized components and successfully tested. Results are rather close to those obtained for individual water electrolysis and H 2 /O 2 fuel cells with the same noble metal loadings and similar operating conditions. For instance, at a current density of 0.2 A/cm 2 , typical cell voltages of ca. 1.55 and 0.70 V were respectively obtained during water electrolysis and H 2 /O 2 fuel cell operation, using Nafion-1135 as solid polymer electrolyte and noble metal loadings 2

PEM fuel cells with injection moulded bipolar plates of highly filled graphite compounds; PEM-Brennstoffzellen mit spritzgegossenen Bipolarplatten aus hochgefuelltem Graphit-Compound

Energy Technology Data Exchange (ETDEWEB)

Kreuz, Can

2008-04-11

This work concerns with the injection moulding of highly filled graphite compounds to bipolar plates for PEM fuel cells in a power output range between 100 - 500 Watts. A particular focus is laid on the combination of the three multidisciplinary scopes like material development, production technology and component development / design. The results of the work are specified by the process-oriented characterisation of the developed and manufactured bipolar plates as well as their application in a functioning fuel cell. (orig.)

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.

Autonomous Operation of Super-Regenerative Receiver in BAN

NARCIS (Netherlands)

Kalyanasundaram, P.; Huang, L.; Dolmans, G.; Imamura, K.

2012-01-01

Super-regenerative receiver is one of the potential candidates to achieve ultra low power wireless communication in body area network (BAN). The main limitations of the super-regenerative receiver include the difficulty in choosing a good quench waveform to optimize its sensitivity and selectivity,

Parameter changes during gradual flooding of a PEM fuel cell through EIS studies; Cambio en parametros de una celda de combustible PEM durante inundacion gradual mediante estudios de EIS

Energy Technology Data Exchange (ETDEWEB)

Cano Castillo, Ulises; Cruz Manzo, Samuel; Arriaga Hurtado, Gerardo [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Ortiz, Alondra; Orozco, German [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S.C. (CIDETEQ) (Mexico)

2008-07-01

The gradual flooding of a single PEM fuel cell was produced and Electrochemical Impedance Spectroscopy (EIS) measurements were realized in order to follow changes of the fuel cell impedance parameters. These changes were followed by using two equivalent circuit models: one simple model of the Randles type accounting for cathode and anode interfaces and a more complex model based on distributed elements, more suitable for porous electrodes in order to include protonic resistance of the catalyst layers. [Spanish] La inundacion gradual de una monocelda de combustible tipo PEM fue estudiada empleando espectroscopia de impedancia electroquimica (EIS), con el proposito de seguir cambios en los parametros de impedancia de la celda. Estos cambios fueron estudiados utilizando dos circuitos equivalentes: un modelo simple de tipo Randles, el cual considerara las interfaces del catodo y del anodo, y un modelo mas complejo basado en elementos distribuidos, el cual fuera adecuado para electrodos porosos, a fin de incluir la resistencia protonica de las capas catalizadoras.

Adaptive controller for regenerative and friction braking system

Science.gov (United States)

Davis, Roy I.

1990-01-01

A regenerative and friction braking system for a vehicle having one or more roadwheels driven by an electric traction motor includes a driver responsive device for producing a brake demand signal having a magnitude corresponding to the level of braking force selected by the driver and friction and regenerative brakes operatively connected with the roadwheels of the vehicle. A system according to this invention further includes control means for operating the friction and regenerative braking subsystems so that maximum brake torques sustainable by the roadwheels of the vehicle without skidding or slipping will not be exceeded.

State of the art: stem cells in equine regenerative medicine.

Science.gov (United States)

Lopez, M J; Jarazo, J

2015-03-01

According to Greek mythology, Prometheus' liver grew back nightly after it was removed each day by an eagle as punishment for giving mankind fire. Hence, contrary to popular belief, the concept of tissue and organ regeneration is not new. In the early 20th century, cell culture and ex vivo organ preservation studies by Alexis Carrel, some with famed aviator Charles Lindbergh, established a foundation for much of modern regenerative medicine. While early beliefs and discoveries foreshadowed significant accomplishments in regenerative medicine, advances in knowledge within numerous scientific disciplines, as well as nano- and micromolecular level imaging and detection technologies, have contributed to explosive advances over the last 20 years. Virtually limitless preparations, combinations and applications of the 3 major components of regenerative medicine, namely cells, biomaterials and bioactive molecules, have created a new paradigm of future therapeutic options for most species. It is increasingly clear, however, that despite significant parallels among and within species, there is no 'one-size-fits-all' regenerative therapy. Likewise, a panacea has yet to be discovered that completely reverses the consequences of time, trauma and disease. Nonetheless, there is no question that the promise and potential of regenerative medicine have forever altered medical practices. The horse is a relative newcomer to regenerative medicine applications, yet there is already a large body of work to incorporate novel regenerative therapies into standard care. This review focuses on the current state and potential future of stem cells in equine regenerative medicine. © 2014 EVJ Ltd.

Habitat Demonstration Unit Project: Leadership and Management Strategies for a Rapid Prototyping Project

Science.gov (United States)

Kennedy, Kriss J.; Toup, Larry; Gill, Tracy; Tri, Terry; Howe, Scott; Smitherman, David

2011-01-01

This paper gives an overview of the National Aeronautics and Space Administration (NASA) led multi-center Habitat Demonstration Unit (HDU) project leadership and management strategies being used by the NASA HDU team for a rapid prototyping project. The HDU project team constructed and tested an analog prototype lunar surface habitat/laboratory called the Pressurized Excursion Module (PEM) during 2010. The prototype unit subsystems were integrated in a short amount of time, utilizing a tiger team rapid prototyping approach that brought together over 20 habitation-related technologies and innovations from a variety of NASA centers. This paper describes the leadership and management strategies as well as lessons learned pertaining to leading and managing a multi-center diverse team in a rapid prototype environment. The PEM configuration went from a paper design to an operational surface habitat demonstration unit in less than 12 months. The HDU project is part of the strategic plan from the Exploration Systems Mission Directorate (ESMD) Directorate Integration Office (DIO) and the Exploration Mission Systems Office (EMSO) to test destination elements in analog environments. The 2011 HDU-Deep Space Habitat (DSH) configuration will build upon the PEM work, and emphasize validity of crew operations (remote working and living), EVA operations, mission operations, logistics operations, and science operations that might be required in a deep space context for Near Earth Object (NEO) exploration mission architectures. The 2011 HDU-DSH will be field-tested during the 2011 Desert Research and Technologies Studies (DRaTS) field tests. The HDU project is a "technology-pull" project that integrates technologies and innovations from multiple NASA centers. This project will repurpose the HDU 2010 demo unit that was field tested in the 2010 DRaTS, adding habitation functionality to the prototype unit. This paper will describe the strategy of establishing a multi-center project

Platelet rich fibrin - a novel acumen into regenerative endodontic therapy

Directory of Open Access Journals (Sweden)

Kavita Hotwani

2014-02-01

Full Text Available Research into regenerative dentistry has added impetus onto the field of molecular biology. It can be documented as a prototype shift in the therapeutic armamentarium for dental disease. Regenerative endodontic procedures are widely being added to the current armamentarium of pulp therapy procedures. The regenerative potential of platelets has been deliberated. A new family of platelet concentrates called the platelet rich fibrin (PRF has been recently used by several investigators and has shown application in diverse disciplines of dentistry. This paper is intended to add light on the various prospects of PRF and clinical insights to regenerative endodontic therapy.

An Intelligent Regenerative Braking Strategy for Electric Vehicles

Directory of Open Access Journals (Sweden)

Zhibin Song

2011-09-01

Full Text Available Regenerative braking is an effective approach for electric vehicles (EVs to extend their driving range. A fuzzy-logic-based regenerative braking strategy (RBS integrated with series regenerative braking is developed in this paper to advance the level of energy-savings. From the viewpoint of securing car stability in braking operations, the braking force distribution between the front and rear wheels so as to accord with the ideal distribution curve are considered to prevent vehicles from experiencing wheel lock and slip phenomena during braking. Then, a fuzzy RBS using the driver’s braking force command, vehicle speed, battery SOC, battery temperature are designed to determine the distribution between friction braking force and regenerative braking force to improve the energy recuperation efficiency. The experimental results on an “LF620” prototype EV validated the feasibility and effectiveness of regenerative braking and showed that the proposed fuzzy RBS was endowed with good control performance. The maximum driving range of LF620 EV was improved by 25.7% compared with non-RBS conditions.

Evaluation strategy of regenerative braking energy for supercapacitor vehicle.

Science.gov (United States)

Zou, Zhongyue; Cao, Junyi; Cao, Binggang; Chen, Wen

2015-03-01

In order to improve the efficiency of energy conversion and increase the driving range of electric vehicles, the regenerative energy captured during braking process is stored in the energy storage devices and then will be re-used. Due to the high power density of supercapacitors, they are employed to withstand high current in the short time and essentially capture more regenerative energy. The measuring methods for regenerative energy should be investigated to estimate the energy conversion efficiency and performance of electric vehicles. Based on the analysis of the regenerative braking energy system of a supercapacitor vehicle, an evaluation system for energy recovery in the braking process is established using USB portable data-acquisition devices. Experiments under various braking conditions are carried out. The results verify the higher efficiency of energy regeneration system using supercapacitors and the effectiveness of the proposed measurement method. It is also demonstrated that the maximum regenerative energy conversion efficiency can reach to 88%. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Compendium of NASA Data Base for the Global Tropospheric Experiment's Pacific Exploratory Mission-Tropics B (PEM-Tropics B). Volume 1; DC-8

Science.gov (United States)

Scott, A. Donald, Jr.; Kleb, Mary M.; Raper, James L.

2000-01-01

This report provides a compendium of NASA aircraft data that are available from NASA's Global Tropospheric Experiment's (GTE) Pacific Exploratory Mission-Tropics B (PEM-Tropics B) conducted in March and April 1999. PEM-Tropics B was conducted during the southern-tropical wet season when the influence from biomass burning observed in PEM-Tropics A was minimal. Major deployment sites were Hawaii, Kiritimati (Christmas Island), Tahiti, Fiji, and Easter Island. The broad goals of PEM-Tropics B were to improved understanding of the oxidizing power of the atmosphere and the processes controlling sulfur aerosol formation and to establish baseline values for chemical species that are directly coupled to the oxidizing power and aerosol loading of the troposphere. The purpose of this document is to provide a representation of aircraft data that will be available in archived format via NASA Langley's Distributed Active Archive Center (DAAC) or are available through the GTE Project Office archive. The data format is not intended to support original research/analysis, but to assist the reader in identifying data that are of interest.

Influence from sea water constituents on the efficiency of water electrolysis by PEM-cells

DEFF Research Database (Denmark)

Agersted, Karsten; Bentzen, Janet Jonna; Yde-Andersen, S.

Among the sea-water specific impurities tested, magnesium has the most profound effect on PEM-cell degradation. Significant amounts of the cation was retrieved in the NAFION®-membrane structure after testing. Degradation was seen from a magnesium concentration as low as 3 10-7 mol/l, and increasing...... with concentration it led to a 86% increase of the area specific resistance at a concentration of 3 10-5 mol/l; equivalent to a conductivity of ~5 μS/cm. Other species (Cl-, Na+, SO4 2- ) seems to affect, though slowly, the performance negatively. If PEM will be used for electrolysis it seems therefore necessary...... to purify the feed water to ~1 μS/cm or even further while particularly focusing on the concentrations of polyvalent cations. e.g. magnesium....

Recent considerations in regenerative endodontic treatment approaches

Directory of Open Access Journals (Sweden)

Hacer Aksel

2014-09-01

Conclusion: Although the regenerative treatment approaches have good clinical outcomes in the majority of case reports, the outcomes are unpredictable. Since the current clinical protocols for regenerative endodontics do not fully fulfill the triad of tissue engineering ((growth factors, scaffold and stem cells, further translational studies are required to achieve more pulp- and dentin-like tissue in the root canal system to achieve pulp regeneration.

Experimental analysis of a PEM fuel cell 15 W; Analise experimental de uma celula a combustivel PEM 15W

Energy Technology Data Exchange (ETDEWEB)

Miyake, Raphael Guardini; Bazzo, Edson [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. Lab. de Combustao e Engenharia de Sistemas Termicos], e-mail: miyake@labcet.ufsc.br, e-mail: ebazzo@emc.ufsc.br

2006-07-01

Fuel cells have been considered a promising alternative for electric energy generation. In order to contribute with the development of this technology, a PEM fuel cell was installed and new experiments were carried out at LabCET (Laboratory of Combustion and Thermal System Engineering). Previous results have shown polarization curves identifying the need of rigorous controlling of humidification temperature of the fuel cell. In this paper, new results were carried out considering the use of a fan connected to the fuel cell and possible degradation in the electrolyte, after a relative long time operation. New polarization curves were plotted for comparison with previous results. (author)

Regenerative endodontics: barriers and strategies for clinical translation.

Science.gov (United States)

Mao, Jeremy J; Kim, Sahng G; Zhou, Jian; Ye, Ling; Cho, Shoko; Suzuki, Takahiro; Fu, Susan Y; Yang, Rujing; Zhou, Xuedong

2012-07-01

Regenerative endodontics has encountered substantial challenges toward clinical translation. The adoption by the American Dental Association of evoked pulp bleeding in immature permanent teeth is an important step for regenerative endodontics. However, there is no regenerative therapy for most endodontic diseases. Simple recapitulation of cell therapy and tissue engineering strategies that are under development for other organ systems has not led to clinical translation in regeneration endodontics. Recent work using novel biomaterial scaffolds and growth factors that orchestrate the homing of host endogenous cells represents a departure from traditional cell transplantation approaches and may accelerate clinical translation. Copyright © 2012 Elsevier Inc. All rights reserved.

Prediction of deformation and hygro-thermal stresses distribution in PEM fuel cell vehicle using three-dimensional CFD model

Energy Technology Data Exchange (ETDEWEB)

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

2012-07-01

Durability is one of the most critical remaining issues impeding successful commercialization of broad PEM fuel cell transportation energy applications. Automotive fuel cells are likely to operate with neat hydrogen under load-following or load-levelled modes and be expected to withstand variations in environmental conditions, particularly in the context of temperature and atmospheric composition. In addition, they are also required to survive over the course of their expected operational lifetimes i.e., around 5,500 hrs, while undergoing as many as 30,000 startup/shutdown cycles. The damage mechanisms in a PEM fuel cell are accelerated by mechanical stresses arising during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running, because it consists of the materials with different thermal expansion and swelling coefficients. Therefore, in order to acquire a complete understanding of the damage mechanisms in the membrane, mechanical response under steady-state hygro-thermal stresses should be studied under real cell operating conditions and in real cell geometry (three-dimensional). In this work, full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to simulate the stresses inside the PEM fuel cell, which are occurring during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running due to the changes of temperature and relative humidity. A unique feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional fuel cell model. In addition, the temperature and humidity dependent material properties are utilize in the simulation for the membrane. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and stresses distribution that have limited experimental data. This model is used to study and analyse the effect of operating parameters on the

Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

2008-01-01

This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...

Performance of PEM Liquid-Feed Direct Methanol-Air Fuel Cells

Science.gov (United States)

Narayanan, S. R.

1995-01-01

A direct methanol-air fuel cell operating at near atmospheric pressure, low-flow rate air, and at temperatures close to 60oC would tremendously enlarge the scope of potential applications. While earlier studies have reported performance with oxygen, the present study focuses on characterizing the performance of a PEM liquid feed direct methanol-air cell consisting of components developed in house. These cells employ Pt-Ru catalyst in the anode, Pt at the cathode and Nafion 117 as the PEM. The effect of pressure, flow rate of air and temperature on cell performance has been studied. With air, the performance level is as high as 0.437 V at 300 mA/cm2 (90oC, 20 psig, and excess air flow) has been attained. Even more significant is the performance level at 60oC, 1 atm and low flow rates of air (3-5 times stoichiometric), which is 0.4 V at 150 mA/cm2. Individual electrode potentials for the methanol and air electrode have been separated and analyzed. Fuel crossover rates and the impact of fuel crossover on the performance of the air electrode have also been measured. The study identifies issues specific to the methanol-air fuel cell and provides a basis for improvement strategies.

Clinical considerations for regenerative endodontic procedures.

Science.gov (United States)

Geisler, Todd M

2012-07-01

The management of a tooth with incomplete root maturation and a necrotic pulp is an endodontic and a restorative challenge. Apexification procedures alone leave the tooth in a weakened state and at risk for reinfection. Regenerative endodontic procedures potentially offer advantages, including the possibility of hard tissue deposition and continued root development. Case studies have reported regeneration of human pulplike tissues in vivo, but there is no protocol that reliably regenerates pulplike tissue. This article summarizes historical, current, and future regenerative treatment approaches. Copyright © 2012 Elsevier Inc. All rights reserved.

Understanding positional cues in salamander limb regeneration: implications for optimizing cell-based regenerative therapies

Directory of Open Access Journals (Sweden)

Catherine D. McCusker

2014-06-01

Full Text Available Regenerative medicine has reached the point where we are performing clinical trials with stem-cell-derived cell populations in an effort to treat numerous human pathologies. However, many of these efforts have been challenged by the inability of the engrafted populations to properly integrate into the host environment to make a functional biological unit. It is apparent that we must understand the basic biology of tissue integration in order to apply these principles to the development of regenerative therapies in humans. Studying tissue integration in model organisms, where the process of integration between the newly regenerated tissues and the ‘old’ existing structures can be observed and manipulated, can provide valuable insights. Embryonic and adult cells have a memory of their original position, and this positional information can modify surrounding tissues and drive the formation of new structures. In this Review, we discuss the positional interactions that control the ability of grafted cells to integrate into existing tissues during the process of salamander limb regeneration, and discuss how these insights could explain the integration defects observed in current cell-based regenerative therapies. Additionally, we describe potential molecular tools that can be used to manipulate the positional information in grafted cell populations, and to promote the communication of positional cues in the host environment to facilitate the integration of engrafted cells. Lastly, we explain how studying positional information in current cell-based therapies and in regenerating limbs could provide key insights to improve the integration of cell-based regenerative therapies in the future.

Repairing quite swimmingly: advances in regenerative medicine using zebrafish.

Science.gov (United States)

Goessling, Wolfram; North, Trista E

2014-07-01

Regenerative medicine has the promise to alleviate morbidity and mortality caused by organ dysfunction, longstanding injury and trauma. Although regenerative approaches for a few diseases have been highly successful, some organs either do not regenerate well or have no current treatment approach to harness their intrinsic regenerative potential. In this Review, we describe the modeling of human disease and tissue repair in zebrafish, through the discovery of disease-causing genes using classical forward-genetic screens and by modulating clinically relevant phenotypes through chemical genetic screening approaches. Furthermore, we present an overview of those organ systems that regenerate well in zebrafish in contrast to mammalian tissue, as well as those organs in which the regenerative potential is conserved from fish to mammals, enabling drug discovery in preclinical disease-relevant models. We provide two examples from our own work in which the clinical translation of zebrafish findings is either imminent or has already proven successful. The promising results in multiple organs suggest that further insight into regenerative mechanisms and novel clinically relevant therapeutic approaches will emerge from zebrafish research in the future. © 2014. Published by The Company of Biologists Ltd.

Development of a portable PEM fuel cell system with bipolar plates consisting an electronically conductive thermoplastic Compound material; Entwicklung eines portablen PEM-Brennstoffzellensystems mit Bipolarplatten aus einem elektronisch leitfaehigen thermoplastischen Compound-Material

Energy Technology Data Exchange (ETDEWEB)

Niemzig, O.C.

2005-07-18

In order to meet the cost targets of PEM fuel cells for commercialization significant cost reductions of cell stack components like membrane/electrode assemblies and bipolar plates have become key aspects of research and development. Central topics of his work are the bipolar plates and humidification for portable applications. Best results concerning conductivity of an extensive screening of a variety of carbon polymer compounds with polypropylene as matrix could be achieved with the carbon black/graphite/polypropylene-base system. Successful tests of this material in a fuel cell stack could be performed as well as the proof of suitability concerning material- and manufacturing costs. Dependent on application a decrease of material cost to 2 Euro/kg to 1,8 Euro/kW seems to be possible. Finally bipolar plates consisting of a selected carbon polymer compound were successfully integrated and tested in a 20-cell stack which was implemented in a portable PEFC-demonstrator unit with a power output between 50 and 150 W. (orig.)

Center for Neuroscience & Regenerative Medicine

Data.gov (United States)

Federal Laboratory Consortium — The Center for Neuroscience and Regenerative Medicine (CNRM) was established as a collaborative intramural federal program involving the U.S. Department of Defense...

Compendium of NASA Data Base for the Global Tropospheric Experiment's Pacific Exploratory Mission - Tropics B (PEM-Tropics B). Volume 2; P-3B

Science.gov (United States)

Scott, A. Donald, Jr.; Kleb, Mary M.; Raper, James L.

2000-01-01

This report provides a compendium of NASA aircraft data that are available from NASA's Global Tropospheric Experiment's (GTE) Pacific Exploratory Mission-Tropics B (PEM-Tropics B) conducted in March and April 1999. PEM-Tropics B was conducted during the southern-tropical wet season when the influence from biomass burning observed in PEM-Tropics A was minimal. Major deployment sites were Hawaii, Kiritimati (Christmas Island), Tahiti, Fiji, and Easter Island. The broad goals of PEM-Tropics B were to improved understanding of the oxidizing power of the atmosphere and the processes controlling sulfur aerosol formation and to establish baseline values for chemical species that are directly coupled to the oxidizing power and aerosol loading of the troposphere. The purpose of this document is to provide a representation of aircraft data that will be available in archived format via NASA Langley's Distributed Active Archive Center (DAAC) or are available through the GTE Project Office archive. The data format is not intended to support original research/analysis, but to assist the reader in identifying data that are of interest.

Stem cell bioprinting for applications in regenerative medicine.

Science.gov (United States)

Tricomi, Brad J; Dias, Andrew D; Corr, David T

2016-11-01

Many regenerative medicine applications seek to harness the biologic power of stem cells in architecturally complex scaffolds or microenvironments. Traditional tissue engineering methods cannot create such intricate structures, nor can they precisely control cellular position or spatial distribution. These limitations have spurred advances in the field of bioprinting, aimed to satisfy these structural and compositional demands. Bioprinting can be defined as the programmed deposition of cells or other biologics, often with accompanying biomaterials. In this concise review, we focus on recent advances in stem cell bioprinting, including performance, utility, and applications in regenerative medicine. More specifically, this review explores the capability of bioprinting to direct stem cell fate, engineer tissue(s), and create functional vascular networks. Furthermore, the unique challenges and concerns related to bioprinting living stem cells, such as viability and maintaining multi- or pluripotency, are discussed. The regenerative capacity of stem cells, when combined with the structural/compositional control afforded by bioprinting, provides a unique and powerful tool to address the complex demands of tissue engineering and regenerative medicine applications. © 2016 New York Academy of Sciences.

Conference Report: 6th Annual International Symposium on Regenerative Rehabilitation.

Science.gov (United States)

Loghmani, M Terry; Roche, Joseph A

2018-04-03

The 6th International Symposium on Regenerative Rehabilitation, hosted by the Alliance for Regenerative Rehabilitation Research and Training (AR 3 T), included a preconference meeting of institutional representatives of the International Consortium of Regenerative Rehabilitation, keynote talks from distinguished scientists, platform and poster presentations from experts and trainees, panel discussions and postconference workshops. The following priorities were identified: increasing rigor in basic, preclinical and clinical studies, especially the use of better controls; developing better outcome measures for preclinical and clinical trials; focusing on developing more tissue-based interventions versus cell-based interventions; including regenerative rehabilitation in curricula of professional programs like occupational and physical therapy; and developing better instruments to quantify rehabilitative interventions.

A high-power compact regenerative amplifier FEL

International Nuclear Information System (INIS)

Nguyen, D.C.; Sheffield, R.L.; Fortgang, C.M.; Kinross-Wright, J.M.; Ebrahim, N.A.; Goldstein, J.C.

1997-01-01

The Regenerative Amplifier FEL (RAFEL) is a new FEL approach aimed at achieving the highest optical power from a compact rf-linac FEL. The key idea is to feed back a small fraction ( 5 in single pass) wiggler to enable the FEL to reach saturation in a few passes. This paper summarizes the design of a high-power compact regenerative amplifier FEL and describes the first experimental demonstration of the RAFEL concept

Early Orthodontic Tooth Movement into Regenerative Bony Defects: A Case Report.

Science.gov (United States)

Tsai, Hui-Chen; Yao, Chung-Chen Jane; Wong, Man-Ying

Early orthodontic tooth movement following regenerative surgery is controversial. In this case, during protraction of the maxillary right first premolar to substitute for the long-term missing maxillary right canine, Bio-Oss and Bio-Gide were used for lateral ridge augmentation at the area of the maxillary right lateral incisor and to cover the denuded surface at the buccal side of the first premolar. Orthodontic tooth movement (OTM) commenced 2 weeks after regenerative surgery. After 8 months, new bone formation was observed on the root surface of the first premolar during implant surgery. A cone beam computed tomography scan taken 1.5 years postsurgery revealed good maintenance of regenerative bone at the same site. This satisfactory outcome of early OTM following regenerative surgery suggests biomechanical stimulation may not jeopardize the regenerative effect.

Regenerative medicine in otorhinolaryngology.

Science.gov (United States)

Wormald, J C R; Fishman, J M; Juniat, S; Tolley, N; Birchall, M A

2015-08-01

Tissue engineering using biocompatible scaffolds, with or without cells, can permit surgeons to restore structure and function following tissue resection or in cases of congenital abnormality. Tracheal regeneration has emerged as a spearhead application of these technologies, whilst regenerative therapies are now being developed to treat most other diseases within otolaryngology. A systematic review of the literature was performed using Ovid Medline and Ovid Embase, from database inception to 15 November 2014. A total of 561 papers matched the search criteria, with 76 fulfilling inclusion criteria. Articles were predominantly pre-clinical animal studies, reflecting the current status of research in this field. Several key human research articles were identified and discussed. The main issues facing research in regenerative surgery are translation of animal model work into human models, increasing stem cell availability so it can be used to further research, and development of better facilities to enable implementation of these advances.

Advancing pig cloning technologies towards application in regenerative medicine.

Science.gov (United States)

Nagashima, H; Matsunari, H; Nakano, K; Watanabe, M; Umeyama, K; Nagaya, M

2012-08-01

Regenerative medicine is expected to make a significant contribution by development of novel therapeutic treatments for intractable diseases and for improving the quality of life of patients. Many advances in regenerative medicine, including basic and translational research, have been developed and tested in experimental animals; pigs have played an important role in various aspects of this work. The value of pigs as a model species is being enhanced by the generation of specially designed animals through cloning and genetic modifications, enabling more sophisticated research to be performed and thus accelerating the clinical application of regenerative medicine. This article reviews the significant aspects of the creation and application of cloned and genetically modified pigs in regenerative medicine research and considers the possible future directions of the technology. We also discuss the importance of reproductive biology as an interface between basic science and clinical medicine. © 2012 Blackwell Verlag GmbH.

Experimental determination of optimal clamping torque for AB-PEM Fuel cell

Directory of Open Access Journals (Sweden)

Noor Ul Hassan

2016-04-01

Full Text Available Polymer electrolyte Membrane (PEM fuel cell is an electrochemical device producing electricity by the reaction of hydrogen and oxygen without combustion. PEM fuel cell stack is provided with an appropriate clamping torque to prevent leakage of reactant gases and to minimize the contact resistance between gas diffusion media (GDL and bipolar plates. GDL porous structure and gas permeability is directly affected by the compaction pressure which, consequently, drastically change the fuel cell performance. Various efforts were made to determine the optimal compaction pressure and pressure distributions through simulations and experimentation. Lower compaction pressure results in increase of contact resistance and also chances of leakage. On the other hand, higher compaction pressure decreases the contact resistance but also narrows down the diffusion path for mass transfer from gas channels to the catalyst layers, consequently, lowering cell performance. The optimal cell performance is related to the gasket thickness and compression pressure on GDL. Every stack has a unique assembly pressure due to differences in fuel cell components material and stack design. Therefore, there is still need to determine the optimal torque value for getting the optimal cell performance. This study has been carried out in continuation of deve­lopment of Air breathing PEM fuel cell for small Unmanned Aerial Vehicle (UAV application. Compaction pressure at minimum contact resistance was determined and clamping torque value was calcu­la­ted accordingly. Single cell performance tests were performed at five different clamping torque values i.e 0.5, 1.0, 1.5, 2.0 and 2.5 N m, for achieving optimal cell per­formance. Clamping pressure distribution tests were also performed at these torque values to verify uniform pressure distribution at optimal torque value. Experimental and theoretical results were compared for making inferences about optimal cell perfor­man­ce. A

Electrochemical characterization of a polybenzimidazole-based high temperature proton exchange membrane unit cell

DEFF Research Database (Denmark)

Jespersen, Jesper Lebæk; Schaltz, Erik; Kær, Søren Knudsen

2009-01-01

This work constitutes detailed EIS (Electrochemical Impedance Spectroscopy) measurements on a PBIbased HT-PEM unit cell. By means of EIS the fuel cell is characterized in several modes of operation by varying the current density, temperature and the stoichiometry of the reactant gases. Using...

Optimization of a thermoelectric generator subsystem for high temperature PEM fuel cell exhaust heat recovery

DEFF Research Database (Denmark)

Gao, Xin; Andreasen, Søren Juhl; Kær, Søren Knudsen

2014-01-01

In previous work, a thermoelectric (TE) exhaust heat recovery subsystem for a high temperature polymer electrolyte membrane (HT-PEM) fuel cell stack was developed and modeled. Numerical simulations were conducted and have identified an optimized subsystem configuration and 4 types of compact heat...... modules are now connected into branches. The procedures of designing and optimizing this TE exhaust heat recovery subsystem are drawn out. The contribution of TE exhaust heat recovery to the HT-PEM fuel cell power system is preliminarily concluded. Its feasibility is also discussed....... exchangers with superior performance for further analysis. In this work, the on-design performances of the 4 heat exchangers are more thoroughly assessed on their corresponding optimized subsystem configurations. Afterward, their off-design performances are compared on the whole working range of the fuel...

Giant hepatic regenerative nodules in Alagille syndrome

Energy Technology Data Exchange (ETDEWEB)

Rapp, Jordan B. [Lewis Katz School of Medicine at Temple University, Department of Radiology, Temple University Hospital, Philadelphia, PA (United States); Bellah, Richard D.; Anupindi, Sudha A. [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); Maya, Carolina [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Pawel, Bruce R. [University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); The Children' s Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, Philadelphia, PA (United States)

2017-02-15

Children with Alagille syndrome undergo surveillance radiologic examinations as they are at risk for developing cirrhosis and hepatocellular carcinoma. There is limited literature on the imaging of liver masses in Alagille syndrome. We report the ultrasound (US) and magnetic resonance imaging (MRI) appearances of incidental benign giant hepatic regenerative nodules in this population. To describe the imaging findings of giant regenerative nodules in patients with Alagille syndrome. A retrospective search of the hospital database was performed to find all cases of hepatic masses in patients with Alagille syndrome during a 10-year period. Imaging, clinical charts, laboratory data and available pathology were reviewed and analyzed and summarized for each patient. Twenty of 45 patients with confirmed Alagille syndrome had imaging studies. Of those, we identified six with giant focal liver masses. All six patients had large central hepatic masses that were remarkably similar on US and MRI, in addition to having features of cirrhosis. In each case, the mass was located in hepatic segment VIII and imaging showed the mass splaying the main portal venous branches at the hepatic hilum, as well as smaller portal and hepatic venous branches coursing through them. On MRI, signal intensity of the mass was isointense to liver on T1-weighted sequences in four of six patients, but hyperintense on T1 in two of six patients. In all six cases, the mass was hypointense on T2- weighted sequences. The mass post-contrast was isointense to adjacent liver in all phases in five the cases. Five out of six patients had pathological correlation demonstrating preserved ductal architecture confirming the final diagnosis of a regenerative nodule. Giant hepatic regenerative nodules with characteristic US and MR features can occur in patients with Alagille syndrome with underlying cirrhosis. Recognizing these lesions as benign giant hepatic regenerative nodules should, thereby, mitigate any need for

Giant hepatic regenerative nodules in Alagille syndrome

International Nuclear Information System (INIS)

Rapp, Jordan B.; Bellah, Richard D.; Anupindi, Sudha A.; Maya, Carolina; Pawel, Bruce R.

2017-01-01

Children with Alagille syndrome undergo surveillance radiologic examinations as they are at risk for developing cirrhosis and hepatocellular carcinoma. There is limited literature on the imaging of liver masses in Alagille syndrome. We report the ultrasound (US) and magnetic resonance imaging (MRI) appearances of incidental benign giant hepatic regenerative nodules in this population. To describe the imaging findings of giant regenerative nodules in patients with Alagille syndrome. A retrospective search of the hospital database was performed to find all cases of hepatic masses in patients with Alagille syndrome during a 10-year period. Imaging, clinical charts, laboratory data and available pathology were reviewed and analyzed and summarized for each patient. Twenty of 45 patients with confirmed Alagille syndrome had imaging studies. Of those, we identified six with giant focal liver masses. All six patients had large central hepatic masses that were remarkably similar on US and MRI, in addition to having features of cirrhosis. In each case, the mass was located in hepatic segment VIII and imaging showed the mass splaying the main portal venous branches at the hepatic hilum, as well as smaller portal and hepatic venous branches coursing through them. On MRI, signal intensity of the mass was isointense to liver on T1-weighted sequences in four of six patients, but hyperintense on T1 in two of six patients. In all six cases, the mass was hypointense on T2- weighted sequences. The mass post-contrast was isointense to adjacent liver in all phases in five the cases. Five out of six patients had pathological correlation demonstrating preserved ductal architecture confirming the final diagnosis of a regenerative nodule. Giant hepatic regenerative nodules with characteristic US and MR features can occur in patients with Alagille syndrome with underlying cirrhosis. Recognizing these lesions as benign giant hepatic regenerative nodules should, thereby, mitigate any need for

Micro-Scale Regenerative Heat Exchanger

Science.gov (United States)

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

2004-01-01

A micro-scale regenerative heat exchanger has been designed, optimized and fabricated for use in a micro-Stirling device. Novel design and fabrication techniques enabled the minimization of axial heat conduction losses and pressure drop, while maximizing thermal regenerative performance. The fabricated prototype is comprised of ten separate assembled layers of alternating metal-dielectric composite. Each layer is offset to minimize conduction losses and maximize heat transfer by boundary layer disruption. A grating pattern of 100 micron square non-contiguous flow passages were formed with a nominal 20 micron wall thickness, and an overall assembled ten-layer thickness of 900 microns. Application of the micro heat exchanger is envisioned in the areas of micro-refrigerators/coolers, micropower devices, and micro-fluidic devices.

The effect of test configuration on the true operating conditions of PEM fuel cells. Paper no. IGEC-1-124

International Nuclear Information System (INIS)

Simpson, T.; Li, X.

2005-01-01

The operating conditions of a single PEM fuel cell can be significantly affected by the configuration in which the fuel cell test is setup. This study investigates the effect on the gas dewpoint temperature of not insulating the inlet fittings to a PEM fuel cell and the effect of non-optimal stack control thermocouple placement on fuel cell stack operating temperature. Both of these setup configurations can significantly affect fuel cell membrane humidification conditions, especially in a single fuel cell as demonstrated through the sample test conditions presented in this paper. (author)

Erich Regener and the ionisation maximum of the atmosphere

Science.gov (United States)

Carlson, P.; Watson, A. A.

2014-12-01

In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

Electrolyte for batteries with regenerative solid electrolyte interface

Science.gov (United States)

Xiao, Jie; Lu, Dongping; Shao, Yuyan; Bennett, Wendy D.; Graff, Gordon L.; Liu, Jun; Zhang, Ji-Guang

2017-08-01

An energy storage device comprising: an anode; and a solute-containing electrolyte composition wherein the solute concentration in the electrolyte composition is sufficiently high to form a regenerative solid electrolyte interface layer on a surface of the anode only during charging of the energy storage device, wherein the regenerative layer comprises at least one solute or solvated solute from the electrolyte composition.

WC as a non-platinum hydrogen evolution electrocatalyst for high temperature PEM water electrolysers

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

2012-01-01

Tungsten carbide (WC) nanopowder was tested as a non-platinum cathode electrocatalyst for polymer electrolyte membrane (PEM) water electrolysers, operating at elevated temperatures. It was prepared in thermal plasma reactor with confined plasma jet from WO3 precursor in combination with CH4...

Intergovernmental Advanced Stationary PEM Fuel Cell System Demonstration Final Report

Energy Technology Data Exchange (ETDEWEB)

Rich Chartrand

2011-08-31

A program to complete the design, construction and demonstration of a PEMFC system fuelled by Ethanol, LPG or NG for telecom applications was initiated in October 2007. Early in the program the economics for Ethanol were shown to be unfeasible and permission was given by DOE to focus on LPG only. The design and construction of a prototype unit was completed in Jun 2009 using commercially available PEM FC stack from Ballard Power Systems. During the course of testing, the high pressure drop of the stack was shown to be problematic in terms of control and stability of the reformer. Also, due to the power requirements for air compression the overall efficiency of the system was shown to be lower than a similar system using internally developed low pressure drop FC stack. In Q3 2009, the decision was made to change to the Plug power stack and a second prototype was built and tested. Overall net efficiency was shown to be 31.5% at 3 kW output. Total output of the system is 6 kW. Using the new stack hardware, material cost reduction of 63% was achieved over the previous Alpha design. During a November 2009 review meeting Plug Power proposed and was granted permission, to demonstrate the new, commercial version of Plug Power's telecom system at CERL. As this product was also being tested as part of a DOE Topic 7A program, this part of the program was transferred to the Topic 7A program. In Q32008, the scope of work of this program was expanded to include a National Grid demonstration project of a micro-CHP system using hightemperature PEM technology. The Gensys Blue system was cleared for unattended operation, grid connection, and power generation in Aug 2009 at Union College in NY state. The system continues to operate providing power and heat to Beuth House. The system is being continually evaluated and improvements to hardware and controls will be implemented as more is learned about the system's operation. The program is instrumental in improving the

Modeling and experimental validation of water mass balance in a PEM fuel cell stack

DEFF Research Database (Denmark)

Liso, Vincenzo; Araya, Samuel Simon; Olesen, Anders Christian

2016-01-01

Polymer electrolyte membrane (PEM) fuel cells require good hydration in order to deliver high performance and ensure long life operation. Water is essential for proton conductivity in the membrane which increases by nearly six orders of magnitude from dry to fully hydrated. Adequate water...... management in PEM fuel cell is crucial in order to avoid an imbalance between water production and water removal from the fuel cell. In the present study, a novel mathematical zero-dimensional model has been formulated for the water mass balance and hydration of a polymer electrolyte membrane. This model...... is validated against experimental data. In the results it is shown that the fuel cell water balance calculated by this model shows better fit with experimental data-points compared with model where only steady state operation were considered. We conclude that this discrepancy is due a different rate of water...

PEM-Scoot - Control system and analysis of operation; PEM-Scoot. Steuerung und Betriebsanalyse. Diplomarbeit 2006/07

Energy Technology Data Exchange (ETDEWEB)

Naegeli, M.; Kaiser, R.

2007-07-01

This diploma thesis presented at the Bernese University of Applied Sciences, Switzerland, describes a project concerning a new drive technology. The PEM-Scoot is a scooter with an electric drive which is powered by a fuel cell, using hydrogen and oxygen stored in two pressure cylinders. That only water is exhausted during operation is considered to be an important advantage. The work done in the project consisted on the one hand of the writing of software for the control and putting it into service and, on the other hand, of various driving tests carried out in order to optimise the control software for stand-alone handling. The planning of the project is described, as are the various components used. The software for the operation of the vehicle is described in detail. The results of driving tests are presented. The report is complemented with a comprehensive appendix.

Regenerative endodontics: A way forward.

Science.gov (United States)

Diogenes, Anibal; Ruparel, Nikita B; Shiloah, Yoav; Hargreaves, Kenneth M

2016-05-01

Immature teeth are susceptible to infections due to trauma, anatomic anomalies, and caries. Traditional endodontic therapies for immature teeth, such as apexification procedures, promote resolution of the disease and prevent future infections. However, these procedures fail to promote continued root development, leaving teeth susceptible to fractures. Regenerative endodontic procedures (REPs) have evolved in the past decade, being incorporated into endodontic practice and becoming a viable treatment alternative for immature teeth. The authors have summarized the status of regenerative endodontics on the basis of the available published studies and provide insight into the different levels of clinical outcomes expected from these procedures. Substantial advances in regenerative endodontics are allowing a better understanding of a multitude of factors that govern stem cell-mediated regeneration and repair of the damaged pulp-dentin complex. REPs promote healing of apical periodontitis, continued radiographic root development, and, in certain cases, vitality responses. Despite the clinical success of these procedures, they appear to promote a guided endodontic repair process rather than a true regeneration of physiological-like tissue. Immature teeth with pulpal necrosis with otherwise poor prognosis can be treated with REPs. These procedures do not preclude the possibility of apexification procedures if attempts are unsuccessful. Therefore, REPs may be considered first treatment options for immature teeth with pulpal necrosis. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

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...

Compact Water Vapor Exchanger for Regenerative Life Support Systems

Science.gov (United States)

Izenson, Michael G.; Chen, Weibo; Anderson, Molly; Hodgson, Edward

2012-01-01

Thermal and environmental control systems for future exploration spacecraft must meet challenging requirements for efficient operation and conservation of resources. Regenerative CO2 removal systems are attractive for these missions because they do not use consumable CO2 absorbers. However, these systems also absorb and vent water to space along with carbon dioxide. This paper describes an innovative device designed to minimize water lost from regenerative CO2 control systems. Design studies and proof-of-concept testing have shown the feasibility of a compact, efficient membrane water vapor exchanger (WVX) that will conserve water while meeting challenging requirements for operation on future spacecraft. Compared to conventional WVX designs, the innovative membrane WVX described here has the potential for high water recovery efficiency, compact size, and very low pressure losses. The key innovation is a method for maintaining highly uniform flow channels in a WVX core built from water-permeable membranes. The proof-of-concept WVX incorporates all the key design features of a prototypical unit, except that it is relatively small scale (1/23 relative to a unit sized for a crew of six) and some components were fabricated using non-prototypical methods. The proof-of-concept WVX achieved over 90% water recovery efficiency in a compact core in good agreement with analysis models. Furthermore the overall pressure drop is very small (less than 0.5 in. H2O, total for both flow streams) and meets requirements for service in environmental control and life support systems on future spacecraft. These results show that the WVX provides very uniform flow through flow channels for both the humid and dry streams. Measurements also show that CO2 diffusion through the water-permeable membranes will have negligible effect on the CO2 partial pressure in the spacecraft atmosphere.

PEMS. Advanced predictive emission monitoring

Energy Technology Data Exchange (ETDEWEB)

Sandvig Nielsen, J.

2010-07-15

In the project PEMS have been developed for boilers, internal combustion engines and gas turbines. The PEMS models have been developed using two principles: The one called ''first principles'' is based on thermo-kinetic modeling of the NO{sub x}-formation by modeling conditions (like temperature, pressure and residence time) in the reaction zones. The other one is data driven using artificial neural network (ANN) and includes no physical properties and no thermo-kinetic formulation. Models of first principles have been developed for gas turbines and gas engines. Data driven models have been developed for gas turbines, gas engines and boilers. The models have been tested on data from sites located in Denmark and the Middle East. Weel and Sandvig has conducted the on-site emission measurements used for development and testing the PEMS models. For gas turbines, both the ''first principles'' and the data driven models have performed excellent considering the ability to reproduce the emission levels of NO{sub x} according to the input variables used for calibration. Data driven models for boilers and gas engines have performed excellent as well. The rather comprehensive first principle model, developed for gas engines, did not perform as well in the prediction of NO{sub x}. Possible a more complex model formulation is required for internal combustion engines. In general, both model types have been validated on data extracted from the data set used for calibration. The data for validation have been selected randomly as individual samplings, and is scattered over the entire measuring campaign. For one natural gas engine a secondary measuring campaign was conducted half a year later than the campaign used for training the data driven model. In the meantime, this engine had been through a refurbishment that included new pistons, piston rings and cylinder linings and cleaning of the cylinder heads. Despite the refurbishment, the

Platelet concentrates: Bioengineering dentistry′s regenerative dreams

Directory of Open Access Journals (Sweden)

Sushma Naag

2015-01-01

Full Text Available Technological advances in the fields of medicine and allied sciences had given much needed momentum into the field of molecular biology and regenerative medicine. They indeed provided a boost to innovate new yields for both hard tissue and soft tissue regeneration in dentistry. One among them is the use of platelet concentrates (platelet rich plasma [PRP], platelet rich fibrin [PRF]. Autologous concentrate of blood platelets with a suspension of growth factors offers an enhanced healing of hard and soft tissues. It is an auxiliary benefit for an operator to be aware of platelet concentrates and its healing properties for delivering unsurpassed oral health care to patients. The current article outlines the principles, objectives and clinical insight to the regenerative potential of platelet concentrates in various fields of dentistry. The search words of the PubMed data base were PRF and other permutations of keywords such as "PRP dentistry", PRF dentistry, PRF regenerative dentistry.

A Comprehensive Review of the Techniques on Regenerative Shock Absorber Systems

Directory of Open Access Journals (Sweden)

Ran Zhang

2018-05-01

Full Text Available In this paper, the current technologies of the regenerative shock absorber systems have been categorized and evaluated. Three drive modes of the regenerative shock absorber systems, namely the direct drive mode, the indirect drive mode and hybrid drive mode are reviewed for their readiness to be implemented. The damping performances of the three different modes are listed and compared. Electrical circuit and control algorithms have also been evaluated to maximize the power output and to deliver the premium ride comfort and handling performance. Different types of parameterized road excitations have been applied to vehicle suspension systems to investigate the performance of the regenerative shock absorbers. The potential of incorporating nonlinearity into the regenerative shock absorber design analysis is discussed. The research gaps for the comparison of the different drive modes and the nonlinearity analysis of the regenerative shock absorbers are identified and, the corresponding research questions have been proposed for future work.

Perivascular cells for regenerative medicine

NARCIS (Netherlands)

M. Crisan (Mihaela); M. Corselli (Mirko); W.C. Chen (William); B. Péault (Bruno)

2012-01-01

textabstractMesenchymal stem/stromal cells (MSC) are currently the best candidate therapeutic cells for regenerative medicine related to osteoarticular, muscular, vascular and inflammatory diseases, although these cells remain heterogeneous and necessitate a better biological characterization. We

Assessing techniques and performance of thin OGFC/PEM overlay on micro-milled surface : final report.

Science.gov (United States)

2014-08-01

The practice of placing an open-graded friction course (OGFC) or a porous European mix (PEM) : directly on top of a conventional milled surface has rarely been done in Georgia due to concerns that this : rehabilitation method could potentially cause ...

The past, present and future of ligament regenerative engineering.

Science.gov (United States)

Mengsteab, Paulos Y; Nair, Lakshmi S; Laurencin, Cato T

2016-12-01

Regenerative engineering has been defined as the convergence of Advanced Materials Sciences, Stem Cell Sciences, Physics, Developmental Biology and Clinical Translation for the regeneration of complex tissues and organ systems. Anterior cruciate ligament (ACL) reconstruction necessitates the regeneration of bone, ligament and their interface to achieve superior clinical results. In the past, the ACL has been repaired with the use of autologous and allogeneic grafts, which have their respective drawbacks. Currently, investigations on the use of biodegradable matrices to achieve knee stability and permit tissue regeneration are making promising advancements. In the future, utilizing regenerative biology cues to induce an endogenous regenerative response may aid the enhancement of clinical ACL reconstruction outcomes.

Regenerative medicine: looking backward 10 years further on.

Science.gov (United States)

Kemp, Paul

2016-12-01

The last decade has seen considerable changes in the Regenerative Medicine industry, but unfortunately the hope for numerous treatments that 'replace or regenerate human cells, tissues or organs to restore or establish normal function' has not yet emerged. In contrast to this, there have been major advances in the field of cellular immunotherapy though some do not consider these to be Regenerative Medicines. Regulatory changes have in some cases improved the route to a marketing license but they have not been matched by clarification of the complex, national reimbursement processes for cell-based treatments and this has adversely affected a number of leading Regenerative Medicine Companies. The review considers the direction that the industry may go in the future in relation to scientific, manufacturing and clinical strategies which may improve the rate of success of new therapies..

The TMI Regenerative Solid Oxide Fuel Cell

Science.gov (United States)

Cable, Thomas L.; Ruhl, Robert C.; Petrik, Michael

1996-01-01

Energy storage and production in space requires rugged, reliable hardware which minimizes weight, volume, and maintenance while maximizing power output and usable energy storage. Systems generally consist of photovoltaic solar arrays which operate (during sunlight cycles) to provide system power and regenerate fuel (hydrogen) via water electrolysis and (during dark cycles) fuel cells convert hydrogen into electricity. Common configurations use two separate systems (fuel cell and electrolyzer) in conjunction with photovoltaic cells. Reliability, power to weight and power to volume ratios could be greatly improved if both power production (fuel cells) and power storage (electrolysis) functions can be integrated into a single unit. The solid oxide fuel cell (SOFC) based design integrates fuel cell and electrolyzer functions and potentially simplifies system requirements. The integrated fuel cell/electrolyzer design also utilizes innovative gas storage concepts and operates like a rechargeable 'hydrogen-oxygen battery'. Preliminary research has been completed on improved H2/H20 electrode (SOFC anode/electrolyzer cathode) materials for regenerative fuel cells. Tests have shown improved cell performance in both fuel and electrolysis modes in reversible fuel cell tests. Regenerative fuel cell efficiencies, ratio of power out (fuel cell mode) to power in (electrolyzer mode), improved from 50 percent using conventional electrode materials to over 80 percent. The new materials will allow a single SOFC system to operate as both the electolyzer and fuel cell. Preliminary system designs have also been developed to show the technical feasibility of using the design for space applications requiring high energy storage efficiencies and high specific energy. Small space systems also have potential for dual-use, terrestrial applications.

Regenerative Endodontics: A Road Less Travelled

Science.gov (United States)

Bansal, Ramta; Mittal, Sunandan; Kumar, Tarun; Kaur, Dilpreet

2014-01-01

Although traditional approaches like root canal therapy and apexification procedures have been successful in treating diseased or infected root canals, but these modalities fail to re-establish healthy pulp tissue in treated teeth. Regeneration-based approaches aims to offer high levels of success by replacing diseased or necrotic pulp tissues with healthy pulp tissue to revitalize teeth. The applications of regenerative approaches in dental clinics have potential to dramatically improve patients’ quality of life. This review article offers a detailed overview of present regenerative endodontic approaches aiming to revitalize teeth and also outlines the problems to be dealt before this emerging field contributes to clinical treatment protocols. It conjointly covers the basic trilogy elements of tissue engineering. PMID:25478476

The positron emission mammography/tomography breast imaging and biopsy system (PEM/PET): design, construction and phantom-based measurements

Science.gov (United States)

Raylman, Raymond R.; Majewski, Stan; Smith, Mark F.; Proffitt, James; Hammond, William; Srinivasan, Amarnath; McKisson, John; Popov, Vladimir; Weisenberger, Andrew; Judy, Clifford O.; Kross, Brian; Ramasubramanian, Srikanth; Banta, Larry E.; Kinahan, Paul E.; Champley, Kyle

2008-02-01

Tomographic breast imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. We have developed a high-resolution positron emission mammography/tomography imaging and biopsy device (called PEM/PET) to detect and guide the biopsy of suspicious breast lesions. PET images are acquired to detect suspicious focal uptake of the radiotracer and guide biopsy of the area. Limited-angle PEM images could then be used to verify the biopsy needle position prior to tissue sampling. The PEM/PET scanner consists of two sets of rotating planar detector heads. Each detector consists of a 4 × 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers (PSPMTs) coupled to a 96 × 72 array of 2 × 2 × 15 mm3 LYSO detector elements (pitch = 2.1 mm). Image reconstruction is performed with a three-dimensional, ordered set expectation maximization (OSEM) algorithm parallelized to run on a multi-processor computer system. The reconstructed field of view (FOV) is 15 × 15 × 15 cm3. Initial phantom-based testing of the device is focusing upon its PET imaging capabilities. Specifically, spatial resolution and detection sensitivity were assessed. The results from these measurements yielded a spatial resolution at the center of the FOV of 2.01 ± 0.09 mm (radial), 2.04 ± 0.08 mm (tangential) and 1.84 ± 0.07 mm (axial). At a radius of 7 cm from the center of the scanner, the results were 2.11 ± 0.08 mm (radial), 2.16 ± 0.07 mm (tangential) and 1.87 ± 0.08 mm (axial). Maximum system detection sensitivity of the scanner is 488.9 kcps µCi-1 ml-1 (6.88%). These promising findings indicate that PEM/PET may be an effective system for the detection and diagnosis of breast cancer.

The positron emission mammography/tomography breast imaging and biopsy system (PEM/PET): design, construction and phantom-based measurements

Energy Technology Data Exchange (ETDEWEB)

Raylman, Raymond R [Center for Advanced Imaging, Department of Radiology, West Virginia University, Morgantown, WV (United States); Majewski, Stan [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Smith, Mark F [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Proffitt, James [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Hammond, William [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Srinivasan, Amarnath [Center for Advanced Imaging, Department of Radiology, West Virginia University, Morgantown, WV (United States); McKisson, John [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Popov, Vladimir [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Weisenberger, Andrew [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Judy, Clifford O [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV (United States); Kross, Brian [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Ramasubramanian, Srikanth [Center for Advanced Imaging, Department of Radiology, West Virginia University, Morgantown, WV (United States); Banta, Larry E [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV (United States); Kinahan, Paul E [Department of Radiology, University of Washington, Seattle, WA (United States); Champley, Kyle [Department of Radiology, University of Washington, Seattle, WA (United States)

2008-02-07

Tomographic breast imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. We have developed a high-resolution positron emission mammography/tomography imaging and biopsy device (called PEM/PET) to detect and guide the biopsy of suspicious breast lesions. PET images are acquired to detect suspicious focal uptake of the radiotracer and guide biopsy of the area. Limited-angle PEM images could then be used to verify the biopsy needle position prior to tissue sampling. The PEM/PET scanner consists of two sets of rotating planar detector heads. Each detector consists of a 4 x 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers (PSPMTs) coupled to a 96 x 72 array of 2 x 2 x 15 mm{sup 3} LYSO detector elements (pitch = 2.1 mm). Image reconstruction is performed with a three-dimensional, ordered set expectation maximization (OSEM) algorithm parallelized to run on a multi-processor computer system. The reconstructed field of view (FOV) is 15 x 15 x 15 cm{sup 3}. Initial phantom-based testing of the device is focusing upon its PET imaging capabilities. Specifically, spatial resolution and detection sensitivity were assessed. The results from these measurements yielded a spatial resolution at the center of the FOV of 2.01 {+-} 0.09 mm (radial), 2.04 {+-} 0.08 mm (tangential) and 1.84 {+-} 0.07 mm (axial). At a radius of 7 cm from the center of the scanner, the results were 2.11 {+-} 0.08 mm (radial), 2.16 {+-} 0.07 mm (tangential) and 1.87 {+-} 0.08 mm (axial). Maximum system detection sensitivity of the scanner is 488.9 kcps {mu}Ci{sup -1} ml{sup -1} (6.88%). These promising findings indicate that PEM/PET may be an effective system for the detection and diagnosis of breast cancer.

Reflective Self-Regenerative Systems Architecture Study

National Research Council Canada - National Science Library

Pu, Carlton; Blough, Douglas

2006-01-01

In this study, we develop the Reflective Self-Regenerative Systems (RSRS) architecture in detail, describing the internal structure of each component and the mutual invocations among the components...

Optimal thermoeconomic performance of an irreversible regenerative ferromagnetic Ericsson refrigeration cycle

International Nuclear Information System (INIS)

Xu, Zhichao; Guo, Juncheng; Lin, Guoxing; Chen, Jincan

2016-01-01

On the basis of the Langevin theory of classical statistical mechanics, the magnetization, entropy, and iso-field heat capacity of ferromagnetic materials are analyzed and their mathematical expressions are derived. An irreversible regenerative Ericsson refrigeration cycle by using a ferromagnetic material as the working substance is established, in which finite heat capacity rates of low and high temperature reservoirs, non-perfect regenerative heat of the refrigeration cycle, additional regenerative heat loss, etc. are taken into account. Based on the regenerative refrigeration cycle model, a thermoeconomic function is introduced as one objective function and optimized with respect to the temperatures of the working substance in the two iso-thermal processes. By means of numerical calculation, the effects of the effective factor of the heat exchangers in high/low temperature reservoir sides, efficiency of the regenerator, heat capacity rate of the low temperature reservoir, and applied magnetic field on the optimal thermoeconomic function as well as the corresponding cooling rate and coefficient of performance are revealed. The results obtained in this paper can provide some theoretical guidance for the optimal design of actual regenerative magnetic refrigerator cycle. - Highlights: • Thermodynamic performance of ferromagnetic material is analyzed. • An irreversible regenerative ferromagnetic Ericsson refrigeration cycle is set up. • The thermoeconomic objective function is introduced and optimized. • Impacts of the thermoeconomic and other parameters are discussed.

Regenerative braking systems with torsional springs made of carbon nanotube yarn

International Nuclear Information System (INIS)

Liu, S; Martin, C; Livermore, C; Lashmore, D; Schauer, M

2014-01-01

The demonstration of large stroke, high energy density and high power density torsional springs based on carbon nanotube (CNT) yarns is reported, as well as their application as an energy-storing actuator for regenerative braking systems. Originally untwisted CNT yarn is cyclically loaded and unloaded in torsion, with the maximum rotation angle increasing until failure. The maximum extractable energy density is measured to be as high as 6.13 kJ/kg. The tests also reveal structural reorganization and hysteresis in the torsional loading curves. A regenerative braking system is built to capture the kinetic energy of a wheel and store it as elastic energy in twisted CNT yarns. When the yam's twist is released, the stored energy reaccelerates the wheel. The measured energy and mean power densities of the CNT yarns in the simple regenerative braking system are up to 4.69 kJ/kg and 1.21 kW/kg, respectively. A slightly lower energy density of up to 1.23 kJ/kg and a 0.29 kW/kg mean power density are measured for the CNT yarns in a more complex system that mimics a unidirectional rotating regenerative braking mechanism. The lower energy densities for CNT yarns in the regenerative braking systems as compared with the yarns themselves reflect the frictional losses of the regenerative systems

Regenerative braking systems with torsional springs made of carbon nanotube yarn

Science.gov (United States)

Liu, S.; Martin, C.; Lashmore, D.; Schauer, M.; Livermore, C.

2014-11-01

The demonstration of large stroke, high energy density and high power density torsional springs based on carbon nanotube (CNT) yarns is reported, as well as their application as an energy-storing actuator for regenerative braking systems. Originally untwisted CNT yarn is cyclically loaded and unloaded in torsion, with the maximum rotation angle increasing until failure. The maximum extractable energy density is measured to be as high as 6.13 kJ/kg. The tests also reveal structural reorganization and hysteresis in the torsional loading curves. A regenerative braking system is built to capture the kinetic energy of a wheel and store it as elastic energy in twisted CNT yarns. When the yam's twist is released, the stored energy reaccelerates the wheel. The measured energy and mean power densities of the CNT yarns in the simple regenerative braking system are up to 4.69 kJ/kg and 1.21 kW/kg, respectively. A slightly lower energy density of up to 1.23 kJ/kg and a 0.29 kW/kg mean power density are measured for the CNT yarns in a more complex system that mimics a unidirectional rotating regenerative braking mechanism. The lower energy densities for CNT yarns in the regenerative braking systems as compared with the yarns themselves reflect the frictional losses of the regenerative systems.

Optimal Control of a PEM Fuel Cell for the Inputs Minimization

Directory of Open Access Journals (Sweden)

José de Jesús Rubio

2014-01-01

Full Text Available The trajectory tracking problem of a proton exchange membrane (PEM fuel cell is considered. To solve this problem, an optimal controller is proposed. The optimal technique has the objective that the system states should reach the desired trajectories while the inputs are minimized. The proposed controller uses the Hamilton-Jacobi-Bellman method where its Riccati equation is considered as an adaptive function. The effectiveness of the proposed technique is verified by two simulations.

Regenerative Intelligent Brake Control for Electric Motorcycles

Directory of Open Access Journals (Sweden)

Juan Jesús Castillo Aguilar

2017-10-01

Full Text Available Vehicle models whose propulsion system is based on electric motors are increasing in number within the automobile industry. They will soon become a reliable alternative to vehicles with conventional propulsion systems. The main advantages of this type of vehicles are the non-emission of polluting gases and noise and the effectiveness of electric motors compared to combustion engines. Some of the disadvantages that electric vehicle manufacturers still have to solve are their low autonomy due to inefficient energy storage systems, vehicle cost, which is still too high, and reducing the recharging time. Current regenerative systems in motorcycles are designed with a low fixed maximum regeneration rate in order not to cause the rear wheel to slip when braking with the regenerative brake no matter what the road condition is. These types of systems do not make use of all the available regeneration power, since more importance is placed on safety when braking. An optimized regenerative braking strategy for two-wheeled vehicles is described is this work. This system is designed to recover the maximum energy in braking processes while maintaining the vehicle’s stability. In order to develop the previously described regenerative control, tyre forces, vehicle speed and road adhesion are obtained by means of an estimation algorithm. A based-on-fuzzy-logic algorithm is programmed to carry out an optimized control with this information. This system recuperates maximum braking power without compromising the rear wheel slip and safety. Simulations show that the system optimizes energy regeneration on every surface compared to a constant regeneration strategy.

Identification of novel mazEF/pemIK family toxin-antitoxin loci and their distribution in the Staphylococcus genus.

Science.gov (United States)

Bukowski, Michal; Hyz, Karolina; Janczak, Monika; Hydzik, Marcin; Dubin, Grzegorz; Wladyka, Benedykt

2017-10-18

The versatile roles of toxin-antitoxin (TA) systems in bacterial physiology and pathogenesis have been investigated for more than three decades. Diverse TA loci in Bacteria and Archaea have been identified in genome-wide studies. The advent of massive parallel sequencing has substantially expanded the number of known bacterial genomic sequences over the last 5 years. In staphylococci, this has translated into an impressive increase from a few tens to a several thousands of available genomes, which has allowed us for the re-evalution of prior conclusions. In this study, we analysed the distribution of mazEF/pemIK family TA system operons in available staphylococcal genomes and their prevalence in mobile genetic elements. 10 novel m azEF/pemIK homologues were identified, each with a corresponding toxin that plays a potentially different and undetermined physiological role. A detailed characterisation of these TA systems would be exceptionally useful. Of particular interest are those associated with an SCCmec mobile genetic element (responsible for multidrug resistance transmission) or representing the joint horizontal transfer of TA systems and determinants of vancomycin resistance from enterococci. The involvement of TA systems in maintaining mobile genetic elements and the associations between novel mazEF/pemIK loci and those which carry drug resistance genes highlight their potential medical importance.

Polarization Curve of a Non-Uniformly Aged PEM Fuel Cell

Directory of Open Access Journals (Sweden)

Andrei Kulikovsky

2014-01-01

Full Text Available We develop a semi-analytical model for polarization curve of a polymer electrolyte membrane (PEM fuel cell with distributed (aged along the oxygen channel MEA transport and kinetic parameters of the membrane–electrode assembly (MEA. We show that the curve corresponding to varying along the channel parameter, in general, does not reduce to the curve for a certain constant value of this parameter. A possibility to determine the shape of the deteriorated MEA parameter along the oxygen channel by fitting the model equation to the cell polarization data is demonstrated.

PEM fuel cell bipolar plate material requirements for transportation applications

Energy Technology Data Exchange (ETDEWEB)

Borup, R.L.; Stroh, K.R.; Vanderborgh, N.E. [Los Alamos National Lab., NM (United States)] [and others

1996-04-01

Cost effective bipolar plates are currently under development to help make proton exchange membrane (PEM) fuel cells commercially viable. Bipolar plates separate individual cells of the fuel cell stack, and thus must supply strength, be electrically conductive, provide for thermal control of the fuel stack, be a non-porous materials separating hydrogen and oxygen feed streams, be corrosion resistant, provide gas distribution for the feed streams and meet fuel stack cost targets. Candidate materials include conductive polymers and metal plates with corrosion resistant coatings. Possible metals include aluminium, titanium, iron/stainless steel and nickel.

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.

Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

Science.gov (United States)

Cikanek, Susan R.

1994-01-01

An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control.

XAS Investigations of PEM Fuel Cells

Science.gov (United States)

Roth, Christina; Ramaker, David E.

Polymer-electrolyte membrane (PEM) fuel cells are still far from an area-wide market launch due in part to long-term stability, reliability and cost issues. A more detailed knowledge of the underlying reaction mechanisms is expected to further their application, as it would allow for the design of tailor-made catalysts. However, this will only be possible by complementing traditional in situ studies on single-crystals in electrochemical cells with more sophisticated metal/electrolyte interfacial studies by novel spectroscopic methodologies, which can provide complementary insights into the behaviour of commercial catalysts under real fuel cell operating conditions. This review will focus on the advances of Xray absorption spectroscopy (XAS) in applied fuel cell research utilizing several examples. XAS enables both the nanoparticle morphology and the adsorbate coverage and binding site to be investigated with just one technique. The latter is possible when complementing the conventional extended X-ray absorption fine structure (EXAFS) analysis with the more novel Δμ XANES approach.

Model-supported characterization of a PEM water electrolysis cell for the effect of compression

DEFF Research Database (Denmark)

Frensch, Steffen Henrik; Olesen, Anders Christian; Simon Araya, Samuel

2018-01-01

This paper investigates the influence of the cell compression of a PEM water electrolysis cell. A small single cell is therefore electrochemically analyzed by means of polarization behavior and impedance spectroscopy throughout a range of currents (0.01 A cm−2 to 2.0 A cm−2) at two temperatures (60...

Human resource development contributes to the creation of outstanding regenerative medicine products

Directory of Open Access Journals (Sweden)

Fusako Nishigaki

2017-12-01

Full Text Available Regenerative medicine is currently the focus of global attention. Countries all around the world are actively working to create new regenerative treatment modalities through pioneering research and novel technologies. This is wonderful news for patients who could not be treated with existing medical options. New venture businesses and companies are being established in regenerative medicine and their rapid industrialization is anticipated. However, to ensure high-quality products, human resources qualified in research and development and the manufacturing of these products are essential. The Forum for Innovative Regenerative Medicine (FIRM conducted a questionnaire of its industry members to examine the training and hiring of people in research and development, product creation, manufacturing, and more. Regenerative medicine is a brand new field; thus, many different businesses will need to cooperate together. People with a broad range of technical skills, abilities, and knowledge will be in demand, with various levels of expertise, from basic to advanced.

Validation of a Waste Heat Recovery Model for a 1kW PEM Fuel Cell using Thermoelectric Generator

Science.gov (United States)

Saufi Sulaiman, M.; Mohamed, W. A. N. W.; Singh, B.; Fitrie Ghazali, M.

2017-08-01

Fuel cell is a device that generates electricity through electrochemical reaction between hydrogen and oxygen. A major by-product of the exothermic reaction is waste heat. The recovery of this waste heat has been subject to research on order to improve the overall energy utilization. However, nearly all of the studies concentrate on high temperature fuel cells using advanced thermodynamic cycles due to the high quality of waste heat. The method, characteristics and challenges in harvesting waste heat from a low temperature fuel cell using a direct energy conversion device is explored in this publication. A heat recovery system for an open cathode 1kW Proton Exchange Membrane fuel cell (PEM FC) was developed using a single unit of thermoelectric generator (TEG) attached to a heat pipe. Power output of the fuel cell was varied to obtain the performance of TEG at different stack temperatures. Natural and forced convections modes of cooling were applied to the TEG cold side. This is to simulate the conditions of a mini fuel cell vehicle at rest and in motion. The experimental results were analysed and a mathematical model based on the thermal circuit analogy was developed and compared. Forced convection mode resulted in higher temperature difference, output voltage and maximum power which are 3.3°C, 33.5 mV, and 113.96mW respectively. The heat recovery system for 1 kW Proton Exchange Membrane fuel cell (PEM FC) using single TEG was successfully established and improved the electrical production of fuel cell. Moreover, the experimental results obtained was in a good agreement with theoretical results.

Bioprinting in Regenerative Medicine

Directory of Open Access Journals (Sweden)

Manuela Monti

2016-02-01

Full Text Available Prof. Turksen is a very well known scientist in the stem cell biology field and he is also internationally known for his fundamental studies on claudin-6. In addition to his research activity he is editor for the Stem Cell Biology and Regenerative Medicine series (Humana Press and editor-in-chief of Stem Cell Reviews and Reports.....

Fuzzy logic electric vehicle regenerative antiskid braking and traction control system

Science.gov (United States)

Cikanek, S.R.

1994-10-25

An regenerative antiskid braking and traction control system using fuzzy logic for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensor and determining if regenerative antiskid braking control, requiring hydraulic braking control, and requiring traction control are required. The processor then employs fuzzy logic based on the determined vehicle state and provides command signals to a motor controller to control operation of the electric traction motor and to the brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative braking control, hydraulic braking control, and traction control. 123 figs.

Microbiological characterization of a regenerative life support system

Science.gov (United States)

Koenig, D. W.; Bruce, R. J.; Mishra, S. K.; Barta, D. J.; Pierson, D. L.

1994-01-01

A Variable Pressure Plant Growth Chamber (VPGC), at the Johnson Space Center's (JSC) ground based Regenerative Life Support Systems (RLSS) test bed, was used to produce crops of soil-grown lettuce. The crops and chamber were analyzed for microbiological diversity during lettuce growth and after harvest. Bacterial counts for the rhizosphere, spent nutrient medium, heat exchanger condensate, and atmosphere were approximately 10(exp 11) Colony Forming Units (CFU)/g, 10(exp 5) CFU/ml, 10(exp 5)CFU/ml, and 600 CFU/m sq, repectively. Pseudomonas was the predominant bacterial genus. Numbers of fungi were about 10(exp 5) CFU/g in the rhizosphere, 4-200 CFU/ml in the spent nutient medium, 110 CFU/ml in the heat exchanger condensate, and 3 CFU/cu m in the atmosphere. Fusarium and Trichoderma were the predominant fungal genera.

A portable power system using PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Long, E. [Ball Aerospace and Technologies Corp., Boulder, CO (United States)

1997-12-31

Ball has developed a proof-of-concept, small, lightweight, portable power system. The power system uses a proton exchange membrane (PEM) fuel cell stack, stored hydrogen, and atmospheric oxygen as the oxidant to generate electrical power. Electronics monitor the system performance to control cooling air and oxidant flow, and automatically do corrective measures to maintain performance. With the controller monitoring the system health, the system can operate in an ambient environment from 0 C to +50 C. The paper describes system testing, including load testing, thermal and humidity testing, vibration and shock testing, field testing, destructive testing of high-pressure gas tanks, and test results on the fuel cell power system, metal hydride hydrogen storage, high-pressure hydrogen gas storage, and chemical hydride hydrogen storage.

Induced pluripotent stem cells for regenerative medicine.

Science.gov (United States)

Hirschi, Karen K; Li, Song; Roy, Krishnendu

2014-07-11

With the discovery of induced pluripotent stem (iPS) cells, it is now possible to convert differentiated somatic cells into multipotent stem cells that have the capacity to generate all cell types of adult tissues. Thus, there is a wide variety of applications for this technology, including regenerative medicine, in vitro disease modeling, and drug screening/discovery. Although biological and biochemical techniques have been well established for cell reprogramming, bioengineering technologies offer novel tools for the reprogramming, expansion, isolation, and differentiation of iPS cells. In this article, we review these bioengineering approaches for the derivation and manipulation of iPS cells and focus on their relevance to regenerative medicine.

Real life testing of a Hybrid PEM Fuel Cell Bus

Science.gov (United States)

Folkesson, Anders; Andersson, Christian; Alvfors, Per; Alaküla, Mats; Overgaard, Lars

Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure. Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system. The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Gröna Bilen" (The Green Car). A 50 kW el fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW. Hybrid Fuel Cell Buses have a big potential, but there are

Development of Low Temperature Catalysts for an Integrated Ammonia PEM Fuel Cell

OpenAIRE

Hill, Alfred

2014-01-01

It is proposed that an integrated ammonia-PEM fuel cell could unlock the potential of ammonia to act as a high capacity chemical hydrogen storage vector and enable renewable energy to be delivered eectively to road transport applications. Catalysts are developed for low temperature ammonia decomposition with activity from 450 K (ruthenium and cesium on graphitised carbon nanotubes). Results strongly suggest that the cesium is present on the surface and close proximity to ruthenium nanoparticl...

Regenerative engineering

CERN Document Server

Laurencin, Cato T

2013-01-01

Regenerative Engineering: The Future of Medicine Saadiq F. El-Amin III , MD , PhD; Joylene W.L. Thomas, MD ; Ugonna N. Ihekweazu, MD ; Mia D. Woods, MS; and Ashim Gupta, MSCell Biology Gloria Gronowicz, PhD and Karen Sagomonyants, DMDStem Cells and Tissue Regeneration Kristen Martins-Taylor, PhD; Xiaofang Wang, MD , PhD; Xue-Jun Li, PhD; and Ren-He Xu, MD , PhDIntroduction to Materials Science Sangamesh G. Kumbar, PhD and Cato T. Laurencin, MD , PhDBiomaterials A. Jon Goldberg, PhD and Liisa T. Kuhn, PhDIn Vitro Assessment of Cell-Biomaterial Interactions Yong Wang, PhDHost Response to Biomate

Commercial Optimization of a 100 kg/day PEM based Hydrogen Generator For Energy and Industrial Applications

International Nuclear Information System (INIS)

Moulthrop, L.; Anderson, E.; Chow, O.; Friedland, R.; Maloney, T.; Schiller, M.

2006-01-01

Commercial hydrogen generators using PEM water electrolysis are well proven, serving industrial applications worldwide in over 50 countries. Now, market and environmental requirements are converging to demand larger on-site hydrogen generators. North American liquid H 2 shortages, increasing trucking costs, developing economies with no liquid infrastructure, utilities, and forklift fuel cell fueling applications are all working to increase market demand for commercial on-site H 2 generation. These commercial applications may be satisfied by a 100 kg H 2 /day module; this platform can be the pathway towards a 500 kg H 2 /day generator desired for small fore-court hydrogen vehicle fueling stations. This paper discusses the steps necessary and activities already underway to develop a 100 to 500 kg H 2 /day PEM hydrogen generator platform to meet commercial market cost targets and approach US DoE transportation fueling cost targets. (authors)

Biomolecule delivery to engineer the cellular microenvironment for regenerative medicine.

Science.gov (United States)

Bishop, Corey J; Kim, Jayoung; Green, Jordan J

2014-07-01

To realize the potential of regenerative medicine, controlling the delivery of biomolecules in the cellular microenvironment is important as these factors control cell fate. Controlled delivery for tissue engineering and regenerative medicine often requires bioengineered materials and cells capable of spatiotemporal modulation of biomolecule release and presentation. This review discusses biomolecule delivery from the outside of the cell inwards through the delivery of soluble and insoluble biomolecules as well as from the inside of the cell outwards through gene transfer. Ex vivo and in vivo therapeutic strategies are discussed, as well as combination delivery of biomolecules, scaffolds, and cells. Various applications in regenerative medicine are highlighted including bone tissue engineering and wound healing.

Electric vehicle regenerative antiskid braking and traction control system

Science.gov (United States)

Cikanek, S.R.

1995-09-12

An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydraulic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control. 10 figs.

Electric vehicle regenerative antiskid braking and traction control system

Science.gov (United States)

Cikanek, Susan R.

1995-01-01

An antiskid braking and traction control system for an electric or hybrid vehicle having a regenerative braking system operatively connected to an electric traction motor, and a separate hydraulic braking system includes one or more sensors for monitoring present vehicle parameters and a processor, responsive to the sensors, for calculating vehicle parameters defining the vehicle behavior not directly measurable by the sensors and determining if regenerative antiskid braking control, requiring hydrualic braking control, or requiring traction control are required. The processor then employs a control strategy based on the determined vehicle state and provides command signals to a motor controller to control the operation of the electric traction motor and to a brake controller to control fluid pressure applied at each vehicle wheel to provide the appropriate regenerative antiskid braking control, hydraulic braking control, and traction control.

Regenerative strategies for the treatment of knee joint disabilities

CERN Document Server

Reis, Rui

2017-01-01

This book presents regenerative strategies for the treatment of knee joint disabilities. The book is composed of four main sections totaling 19 chapters which review the current knowledge on the clinical management and preclinical regenerative strategies. It examines the role of different natural-based biomaterials as scaffolds and implants for addressing different tissue lesions in the knee joint. Section one provides an updated and comprehensive discussion on articular cartilage tissue regeneration. Section two focuses on the important contributions for bone and osteochondral tissue engineering. Section three overview the recent advances on meniscus repair/regeneration strategies. Finally, section four further discusses the current strategies for treatment of ligament lesions. Each chapter is prepared by world know expert on their fields, so we do firmly believe that the proposed book will be a reference in the area of biomaterials for regenerative medicine.

Internal Heating of an IGBT module in a System With a Regenerative AC Drive

OpenAIRE

Mabano, Michel

2016-01-01

The purpose of this thesis was to understand the internal heating of an IGBT module inside an AC drive in a system with a regenerative unit to it. During the implementation of the lab, various approaches were taken in an effort to collect measurements appropriate to the topic of investigation. The IGBT junction temperature was recorded over a sustained period of time at various speed of the induction motor. The braking torque applied through a second AC drive was varied in order to study...

A CFD analysis on the effect of ambient conditions on the hygro-thermal stresses distribution in a planar ambient air-breathing PEM fuel cell

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2011-01-01

The need for improved lifetime of air-breathing proton exchange membrane (PEM) fuel cells for portable applications necessitates that the failure mechanisms be clearly understood and life prediction models be developed, so that new designs can be introduced to improve long-term performance. An operating air-breathing PEM fuel cell has varying local conditions of temperature and humidity. As a result of in the changes in temperature and moisture, the membrane, GDL and bipolar plates will all e...

Design and experiment study of a semi-active energy-regenerative suspension system

International Nuclear Information System (INIS)

Shi, Dehua; Chen, Long; Wang, Ruochen; Jiang, Haobin; Shen, Yujie

2015-01-01

A new kind of semi-active energy-regenerative suspension system is proposed to recover suspension vibration energy, as well as to reduce the suspension cost and demands for the motor-rated capacity. The system consists of an energy-regenerative damper and a DC-DC converter-based energy-regenerative circuit. The energy-regenerative damper is composed of an electromagnetic linear motor and an adjustable shock absorber with three regulating levels. The linear motor just works as the generator to harvest the suspension vibration energy. The circuit can be used to improve the system’s energy-regenerative performance and to continuously regulate the motor’s electromagnetic damping force. Therefore, although the motor works as a generator and damps the isolation without an external power source, the motor damping force is controllable. The damping characteristics of the system are studied based on a two degrees of freedom vehicle vibration model. By further analyzing the circuit operation characteristics under different working modes, the double-loop controller is designed to track the desired damping force. The external-loop is a fuzzy controller that offers the desired equivalent damping. The inner-loop controller, on one hand, is used to generate the pulse number and the frequency to control the angle and the rotational speed of the step motor; on the other hand, the inner-loop is used to offer the duty cycle of the energy-regenerative circuit. Simulations and experiments are conducted to validate such a new suspension system. The results show that the semi-active energy-regenerative suspension can improve vehicle ride comfort with the controllable damping characteristics of the linear motor. Meanwhile, it also ensures energy regeneration. (paper)

Synthesis of protons exchange polymeric membranes via co-poly-esters doped with sodium dodecyl sulfate for application in PEM fuel cells; Sintese de membranas polimericas condutoras de protons por imobilizacao de MDs em copoliesteres para aplicacao em PEM-FC

Energy Technology Data Exchange (ETDEWEB)

Fiuza, R.A.; Brioude, M.M.; Bresciani, D.; Jose, N.M.; Boaventura, J.S. [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica

2008-07-01

Polymers are largely studied for use in PEM-type fuel cell (Proton Exchange membrane, PEMFC). These fuel cells are based on polymer membranes as electrolyte, also called protons conductor. This work developed co-polyesters made electrical conductors by doping with sodium dodecyl sulfate. The copolymers were synthesized from the copolymerization of terephthalic and adipic acids with glycerol. The material was processed in a reactor and shaped by hot pressing, yielding homogeneous and flexible plates, with excellent surface finish. The co-polyesters were analyzed by SEM, FTIR, TG, DSC, and XRD. The thermal analysis showed that the composites were thermally stable up to about 250 deg C. The micrographics revealed the MDS homogeneously dispersed in the polymeric matrix. These copolymers showed electrical conductivity between 10-7 to 10-1 S/cm, suggesting strong potential use in PEM fuel cells. (author)

Process for recycling components of a PEM fuel cell membrane electrode assembly

Science.gov (United States)

Shore, Lawrence [Edison, NJ

2012-02-28

The membrane electrode assembly (MEA) of a PEM fuel cell can be recycled by contacting the MEA with a lower alkyl alcohol solvent which separates the membrane from the anode and cathode layers of the assembly. The resulting solution containing both the polymer membrane and supported noble metal catalysts can be heated under mild conditions to disperse the polymer membrane as particles and the supported noble metal catalysts and polymer membrane particles separated by known filtration means.

Stem Cell Therapy: Repurposing Cell-Based Regenerative Medicine Beyond Cell Replacement.

Science.gov (United States)

Napoli, Eleonora; Lippert, Trenton; Borlongan, Cesar V

2018-02-27

Stem cells exhibit simple and naive cellular features, yet their exact purpose for regenerative medicine continues to elude even the most elegantly designed research paradigms from developmental biology to clinical therapeutics. Based on their capacity to divide indefinitely and their dynamic differentiation into any type of tissue, the advent of transplantable stem cells has offered a potential treatment for aging-related and injury-mediated diseases. Recent laboratory evidence has demonstrated that transplanted human neural stem cells facilitate endogenous reparative mechanisms by initiating multiple regenerative processes in the brain neurogenic areas. Within these highly proliferative niches reside a myriad of potent regenerative molecules, including anti-inflammatory cytokines, proteomes, and neurotrophic factors, altogether representing a biochemical cocktail vital for restoring brain function in the aging and diseased brain. Here, we advance the concept of therapeutically repurposing stem cells not towards cell replacement per se, but rather exploiting the cells' intrinsic properties to serve as the host brain regenerative catalysts.

Dental pulp stem cells: function, isolation and applications in regenerative medicine.

Science.gov (United States)

Tatullo, Marco; Marrelli, Massimo; Shakesheff, Kevin M; White, Lisa J

2015-11-01

Dental pulp stem cells (DPSCs) are a promising source of cells for numerous and varied regenerative medicine applications. Their natural function in the production of odontoblasts to create reparative dentin support applications in dentistry in the regeneration of tooth structures. However, they are also being investigated for the repair of tissues outside of the tooth. The ease of isolation of DPSCs from discarded or removed teeth offers a promising source of autologous cells, and their similarities with bone marrow stromal cells (BMSCs) suggest applications in musculoskeletal regenerative medicine. DPSCs are derived from the neural crest and, therefore, have a different developmental origin to BMSCs. These differences from BMSCs in origin and phenotype are being exploited in neurological and other applications. This review briefly highlights the source and functions of DPSCs and then focuses on in vivo applications across the breadth of regenerative medicine. © 2014 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.

Characterisation and Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Schaltz, Erik

2009-01-01

temperature PEM (HTPEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell, is a Nyquist plot, which shows the imaginary and real part of the impedance...

Regenerative Medicine: Advances from Developmental to Degenerative Diseases.

Science.gov (United States)

Blair, Nicholas F; Frith, Thomas J R; Barbaric, Ivana

2017-01-01

Chronic tissue and organ failure caused by an injury, disease, ageing or congenital defects represents some of the most complex therapeutic challenges and poses a significant financial healthcare burden. Regenerative medicine strategies aim to fulfil the unmet clinical need by restoring the normal tissue function either through stimulating the endogenous tissue repair or by using transplantation strategies to replace the missing or defective cells. Stem cells represent an essential pillar of regenerative medicine efforts as they provide a source of progenitors or differentiated cells for use in cell replacement therapies. Whilst significant leaps have been made in controlling the stem cell fates and differentiating them to cell types of interest, transitioning bespoke cellular products from an academic environment to off-the-shelf clinical treatments brings about a whole new set of challenges which encompass manufacturing, regulatory and funding issues. Notwithstanding the need to resolve such issues before cell replacement therapies can benefit global healthcare, mounting progress in the field has highlighted regenerative medicine as a realistic prospect for treating some of the previously incurable conditions.

Prospective regenerative medicine therapies for obstetric trauma-induced fecal incontinence.

Science.gov (United States)

Parmar, Nina; Kumar, Lalit; Emmanuel, Anton; Day, Richard M

2014-01-01

Fecal incontinence is a major public health issue that has yet to be adequately addressed. Obstetric trauma and injury to the anal sphincter muscles are the most common cause of fecal incontinence. New therapies are emerging aimed at repair or regeneration of sphincter muscle and restoration of continence. While regenerative medicine offers an attractive option for fecal incontinence there are currently no validated techniques using this approach. Although many challenges are yet to be resolved, the advent of regenerative medicine is likely to offer disruptive technologies to treat and possibly prevent the onset of this devastating condition. This article provides a review on regenerative medicine approaches for treating fecal incontinence and a critique of the current landscape in this area.

Effects of clamping force on the water transport and performance of a PEM (proton electrolyte membrane) fuel cell with relative humidity and current density

International Nuclear Information System (INIS)

Cha, Dowon; Ahn, Jae Hwan; Kim, Hyung Soon; Kim, Yongchan

2015-01-01

The clamping force should be applied to a proton electrolyte membrane (PEM) fuel cell due to its structural characteristics. The clamping force affects the ohmic and mass transport resistances in the PEM fuel cell. In this study, the effects of the clamping force on the water transport and performance characteristics of a PEM fuel cell are experimentally investigated with variations in the relative humidity and current density. The water transport characteristics were analyzed by calculating the net drag coefficient. The ohmic resistance decreased with the increase in the clamping force due to the reduced contact resistance and more even membrane hydration. However, the mass transport resistance increased with the increase in the clamping force due to the gas diffusion layer compression. The net drag coefficient decreased with the increase in the clamping force due to high water back-diffusion. Additionally, the relationship between the total resistance and the net drag coefficient was investigated. - Highlights: • Effects of clamping force on the performance of a PEM fuel cell are investigated. • Water transport characteristics are analyzed using net drag coefficient. • Ohmic resistance decreased with clamping force, but mass transport resistance increased. • Net drag coefficient decreased with the increase in clamping force. • Total resistance was significantly degraded for a net drag coefficient below 0.2.

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

Science.gov (United States)

Xu, Kun; Xu, Guo-Qing; Zheng, Chun-Hua

2016-04-01

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability, improving the adhesion utilization, and achieving deep energy recovery. There remain technical challenges mainly because of the nonlinear, uncertain, and varying features of wheel-rail contact conditions. This research analyzes the torque transmitting behavior during regenerative braking, and proposes a novel methodology to detect the wheel-rail adhesion stability. Then, applications to the wheel slip prevention during braking are investigated, and the optimal slip ratio control scheme is proposed, which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control. The proposed methodology achieves the optimal braking performance without the wheel-rail contact information. Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

Regenerative feedback resonant circuit

Science.gov (United States)

Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

2014-09-02

A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

Carbon nanotube torsional springs for regenerative braking systems

Science.gov (United States)

Liu, Sanwei; Martin, Corbin; Lashmore, David; Schauer, Mark; Livermore, Carol

2015-10-01

The modeling and demonstration of large stroke, high energy density and high power density torsional springs based on carbon nanotube (CNT) yarns is reported, as well as their application as energy-storing actuators for regenerative braking systems. An originally untwisted CNT yarn is cyclically loaded and unloaded in torsion, with the maximum rotation angle increasing incrementally until failure. The measured average extractable energy density values are 2.9 kJ kg-1  ±  1.2 kJ kg-1 and 3.4 kJ kg-1  ±  0.4 kJ kg-1 for 1-ply CNT yarns and 2-ply CNT yarns, respectively. Additionally, a regenerative braking system is demonstrated to capture the kinetic energy of a wheel and store it as elastic energy in twisted CNT yarns. When the yarn’s twist is released, the stored energy reaccelerates the wheel. The measured energy and mean power densities of the CNT yarns in the simple regenerative braking setup are on average 3.3 kJ kg-1 and 0.67 kW kg-1, respectively, with maximum measured values of up to 4.7 kJ kg-1 and 1.2 kW kg-1, respectively. A slightly lower energy density of up to 1.2 kJ kg-1 and a 0.29 kW kg-1 mean power density are measured for CNT yarns in a more complex setup that mimics a unidirectional rotating regenerative braking mechanism.

A survey of attitude and opinions of endodontic residents towards regenerative endodontics

Science.gov (United States)

Utneja, Shivani; Nawal, Ruchika Roongta; Ansari, Mohammed Irfan; Talwar, Sangeeta; Verma, Mahesh

2013-01-01

Aim: The objective of this survey was to study the level of awareness, current state of knowledge and opinions towards regenerative endodontic treatments amongst the endodontic residents of India. Settings and Design: Questionnaire based survey was designed. Materials and Methods: After approval from the organizing committee of 26th Federation of Operative Dentistry of India and 19th Indian Endodontic Society National conference 2011, 200 copies of the questionnaire were circulated amongst the endodontic residents in conservative dentistry and endodontics at various colleges across the country about regenerative endodontic procedures. The survey included profile of the respondents and consisted of 23 questions about their knowledge, attitude and opinions regarding use of these procedures as part of future dental treatment. Results: The survey showed that half the participants (50.6%) had received continued education in stem cells and/or regenerative dental treatments. The majority of participants were of the opinion (86.6%) that regenerative therapy should be incorporated into dentistry, and most of them (88%) were willing to acquire training in learning this new treatment strategy. The results indicated that half of the participants (52.6%) were already using some type of regenerative therapy in their clinical practice; however, with a majority of these limited to use of membranes, scaffolds or bioactive materials. Conclusions: These results reflect that endodontic residents are optimistic about the use of regenerative endodontic procedures; however, a need for more research and training was felt. PMID:23956532

Regenerative Engineering and Bionic Limbs.

Science.gov (United States)

James, Roshan; Laurencin, Cato T

2015-03-01

Amputations of the upper extremity are severely debilitating, current treatments support very basic limb movement, and patients undergo extensive physiotherapy and psychological counselling. There is no prosthesis that allows the amputees near-normal function. With increasing number of amputees due to injuries sustained in accidents, natural calamities and international conflicts, there is a growing requirement for novel strategies and new discoveries. Advances have been made in technological, material and in prosthesis integration where researchers are now exploring artificial prosthesis that integrate with the residual tissues and function based on signal impulses received from the residual nerves. Efforts are focused on challenging experts in different disciplines to integrate ideas and technologies to allow for the regeneration of injured tissues, recording on tissue signals and feed-back to facilitate responsive movements and gradations of muscle force. A fully functional replacement and regenerative or integrated prosthesis will rely on interface of biological process with robotic systems to allow individual control of movement such as at the elbow, forearm, digits and thumb in the upper extremity. Regenerative engineering focused on the regeneration of complex tissue and organ systems will be realized by the cross-fertilization of advances over the past thirty years in the fields of tissue engineering, nanotechnology, stem cell science, and developmental biology. The convergence of toolboxes crated within each discipline will allow interdisciplinary teams from engineering, science, and medicine to realize new strategies, mergers of disparate technologies, such as biophysics, smart bionics, and the healing power of the mind. Tackling the clinical challenges, interfacing the biological process with bionic technologies, engineering biological control of the electronic systems, and feed-back will be the important goals in regenerative engineering over the next

The use of a medical dictionary for regulatory activities terminology (MedDRA) in prescription-event monitoring in Japan (J-PEM).

Science.gov (United States)

Yokotsuka, M; Aoyama, M; Kubota, K

2000-07-01

The Medical Dictionary for Regulatory Activities Terminology (MedDRA) version 2.1 (V2.1) was released in March 1999 accompanied by the MedDRA/J V2.1J specifically for Japanese users. In prescription-event monitoring in Japan (J-PEM), we have employed the MedDRA/J for data entry, signal generation and event listing. In J-PEM, the lowest level terms (LLTs) in the MedDRA/J are used in data entry because the richness of LLTs is judged to be advantageous. A signal is generated normally at the preferred term (PT) level, but it has been found that various reporters describe the same event using descriptions that are potentially encoded by LLTs under different PTs. In addition, some PTs are considered too specific to generate the proper signal. In the system used in J-PEM, when an LLT is selected as a candidate to encode an event, another LLT under a different PT, if any, is displayed on the computer screen so that it may be coded instead of, or in addition to, the candidate LLT. The five-level structure of the MedDRA is used when listing events but some modification is required to generate a functional event list.

Nanotechnology and regenerative therapeutics in plastic surgery: The next frontier

Science.gov (United States)

Tan, Aaron; Chawla, Reema; Natasha, G; Mahdibeiraghdar, Sara; Jeyaraj, Rebecca; Rajadas, Jayakumar; Hamblin, Michael R.; Seifalian, Alexander M.

2015-01-01

Summary The rapid ascent of nanotechnology and regenerative therapeutics as applied to medicine and surgery has seen an exponential rise in the scale of research generated in this field. This is evidenced not only by the sheer volume of papers dedicated to nanotechnology but also in a large number of new journals dedicated to nanotechnology and regenerative therapeutics specifically to medicine and surgery. Aspects of nanotechnology that have already brought benefits to these areas include advanced drug delivery platforms, molecular imaging and materials engineering for surgical implants. Particular areas of interest include nerve regeneration, burns and wound care, artificial skin with nanoelectronic sensors and head and neck surgery. This study presents a review of nanotechnology and regenerative therapeutics, with focus on its applications and implications in plastic surgery. PMID:26422652

LOX/Methane Regeneratively-Cooled Rocket Engine Development

Data.gov (United States)

National Aeronautics and Space Administration — The purpose of this project is to advance the technologies required to build a subcritical regeneratively cooled liquid oxygen/methane rocket combustion chamber for...

From regenerative dentistry to regenerative medicine: progress, challenges, and potential applications of oral stem cells

Directory of Open Access Journals (Sweden)

Xiao L

2014-12-01

Full Text Available Li Xiao,1 Masanori Nasu2 1Department of Pharmacology, 2Research Center, The Nippon Dental University, Tokyo, Japan Abstract: Adult mesenchymal stem cells (MSCs and epithelial stem cells play essential roles in tissue repair and self-healing. Oral MSCs and epithelial stem cells can be isolated from adult human oral tissues, for example, teeth, periodontal ligament, and gingiva. Cocultivated adult oral epithelial stem cells and MSCs could represent some developmental events, such as epithelial invagination and tubular structure formation, signifying their potentials for tissue regeneration. Oral epithelial stem cells have been used in regenerative medicine over 1 decade. They are able to form a stratified cell sheet under three-dimensional culture conditions. Both experimental and clinical data indicate that the cell sheets can not only safely and effectively reconstruct the damaged cornea in humans, but also repair esophageal ulcer in animal models. Oral MSCs include dental pulp stem cells (DPSCs, stem cells from exfoliated deciduous teeth (SHED, stem cells from apical papilla (SCAP, periodontal ligament stem cells (PDLSCs, and mesenchymal stem cells from gingiva (GMSCs. They are widely applied in both regenerative dentistry and medicine. DPSCs, SHED, and SCAP are able to form dentin–pulp complex when being transplanted into immunodeficient animals. They have been experimentally used for the regeneration of dental pulp, neuron, bone muscle and blood vessels in animal models and have shown promising results. PDLSCs and GMSCs are demonstrated to be ideal cell sources for repairing the damaged tissues of periodontal, muscle, and tendon. Despite the abovementioned applications of oral stem cells, only a few human clinical trials are now underway to use them for the treatment of certain diseases. Since clinical use is the end goal, their true regenerative power and safety need to be further examined.Keywords: oral mesenchymal stem cells, oral

[Progress in stem cells and regenerative medicine].

Science.gov (United States)

Wang, Libin; Zhu, He; Hao, Jie; Zhou, Qi

2015-06-01

Stem cells have the ability to differentiate into all types of cells in the body and therefore have great application potential in regenerative medicine, in vitro disease modelling and drug screening. In recent years, stem cell technology has made great progress, and induced pluripotent stem cell technology revolutionizes the whole stem cell field. At the same time, stem cell research in our country has also achieved great progress and becomes an indispensable power in the worldwide stem cell research field. This review mainly focuses on the research progress in stem cells and regenerative medicine in our country since the advent of induced pluripotent stem cell technology, including induced pluripotent stem cells, transdifferentiation, haploid stem cells, and new gene editing tools.

Fabrication and in vitro evaluation of the collagen/hyaluronic acid PEM coating crosslinked with functionalized RGD peptide on titanium.

Science.gov (United States)

Huang, Ying; Luo, Qiaojie; Li, Xiaodong; Zhang, Feng; Zhao, Shifang

2012-02-01

Surface modification of titanium (Ti) using biomolecules has attracted much attention recently. In this study, a new strategy has been employed to construct a stable and bioactive coating on Ti. To this end, a derivative of hyaluronic acid (HA), i.e. HA-GRGDSPC-(SH), was synthesized. The disulfide-crosslinked Arg-Gly-Asp (RGD)-containing collagen/hyaluronic acid polyelectrolyte membrane (PEM) coating was then fabricated on Ti through the alternate deposition of collagen and HA-GRGDSPC-(SH) with five assembly cycles and subsequent crosslinking via converting free sulphydryl groups into disulfide linkages (RGD-CHC-Ti group). The assembly processes for PEM coating and the physicochemical properties of the coating were carefully characterized. The stability of PEM coating in phosphate-buffered saline solution could be adjusted by the crosslinking degree, while its degradation behaviors in the presence of glutathione were glutathione concentration dependent. The adhesion and proliferation of MC3T3-E1 cells were significantly enhanced in the RGD-CHC-Ti group. Up-regulated bone specific genes, enhanced alkaline phosphatase activity and osteocalcin production, the increased areas of mineralization were also observed in the RGD-CHC-Ti group. These results indicate that the strategy employed herein may function as an effective way to construct stable, RGD-containing bioactive coatings on Ti. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of integrated system to operational control and monitoring for PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Mauricio Stelita; Ferreira, Valdemar Stelita [NovoCell Sistemas de Energia S.A., Santa Barbara D' Oeste, SP (Brazil)], Email: mauricio.ferreira@novocell.ind.br

2010-07-01

The demonstration of fuel cells prototype in some applications such as in stationary systems and vehicles has been increased, but higher costs and lack of criteria for system longevity still prevent their mass production. Acting directly on this aspect, Novocell has proposed to develop innovative processes and materials to manufacture at scale and with competitive cost for these systems. Thus, this paper presents solutions that enable its production line of PEM fuel cells. (author)

Experimental validation of modelling tools for a PEM fuel cell; Validation experimentale d'outils de modelisation d'une pile a combustible de type PEM

Energy Technology Data Exchange (ETDEWEB)

Boillot, M.

2005-10-15

In this work, a global view of the phenomena occurring in a PEM fuel cell is given. An original methodology was developed in order to determine the main parameters: thermodynamics, kinetics and transport phenomena. The gas flow in bipolar plates was characterised using experimental determination of residence time distributions and numerical simulations. Kinetics of both electrochemical reactions were analysed feeding the cell by diluted gases. In this part, the diffusion of reactants in the membrane electrodes assembly was taken into account. Finally, the relationship between humidity and electrical performance was investigated and the ohmic resistance of the cell was estimated. (author)

Sliding-Mode Control of PEM Fuel Cells

CERN Document Server

Kunusch, Cristian; Mayosky, Miguel

2012-01-01

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

The imperative for regenerative agriculture.

Science.gov (United States)

Rhodes, Christopher J

2017-03-01

A review is made of the current state of agriculture, emphasising issues of soil erosion and dependence on fossil fuels, in regard to achieving food security for a relentlessly enlarging global population. Soil has been described as "the fragile, living skin of the Earth", and yet both its aliveness and fragility have all too often been ignored in the expansion of agriculture across the face of the globe. Since it is a pivotal component in a global nexus of soil-water-air-energy, how we treat the soil can impact massively on climate change - with either beneficial or detrimental consequences, depending on whether the soil is preserved or degraded. Regenerative agriculture has at its core the intention to improve the health of soil or to restore highly degraded soil, which symbiotically enhances the quality of water, vegetation and land-productivity. By using methods of regenerative agriculture, it is possible not only to increase the amount of soil organic carbon (SOC) in existing soils, but to build new soil. This has the effect of drawing down carbon from the atmosphere, while simultaneously improving soil structure and soil health, soil fertility and crop yields, water retention and aquifer recharge - thus ameliorating both flooding and drought, and also the erosion of further soil, since runoff is reduced. Since food production on a more local scale is found to preserve the soil and its quality, urban food production should be seen as a significant potential contributor to regenerative agriculture in the future, so long as the methods employed are themselves 'regenerative'. If localisation is to become a dominant strategy for dealing with a vastly reduced use of fossil fuels, and preserving soil quality - with increased food production in towns and cities - it will be necessary to incorporate integrated ('systems') design approaches such as permaculture and the circular economy (which minimise and repurpose 'waste') within the existing urban infrastructure. In

Carbon nanotube torsional springs for regenerative braking systems

International Nuclear Information System (INIS)

Liu, Sanwei; Martin, Corbin; Livermore, Carol; Lashmore, David; Schauer, Mark

2015-01-01

The modeling and demonstration of large stroke, high energy density and high power density torsional springs based on carbon nanotube (CNT) yarns is reported, as well as their application as energy-storing actuators for regenerative braking systems. An originally untwisted CNT yarn is cyclically loaded and unloaded in torsion, with the maximum rotation angle increasing incrementally until failure. The measured average extractable energy density values are 2.9 kJ kg −1   ±  1.2 kJ kg −1 and 3.4 kJ kg −1   ±  0.4 kJ kg −1 for 1-ply CNT yarns and 2-ply CNT yarns, respectively. Additionally, a regenerative braking system is demonstrated to capture the kinetic energy of a wheel and store it as elastic energy in twisted CNT yarns. When the yarn’s twist is released, the stored energy reaccelerates the wheel. The measured energy and mean power densities of the CNT yarns in the simple regenerative braking setup are on average 3.3 kJ kg −1 and 0.67 kW kg −1 , respectively, with maximum measured values of up to 4.7 kJ kg −1 and 1.2 kW kg −1 , respectively. A slightly lower energy density of up to 1.2 kJ kg −1 and a 0.29 kW kg −1 mean power density are measured for CNT yarns in a more complex setup that mimics a unidirectional rotating regenerative braking mechanism. (paper)

New evaluation methodology of regenerative braking contribution to energy efficiency improvement of electric vehicles

International Nuclear Information System (INIS)

Qiu, Chengqun; Wang, Guolin

2016-01-01

Highlights: • Two different contribution ratio evaluation parameters according to the deceleration braking process are proposed. • Methodologies for calculating the contribution made by regenerative brake to improve vehicle energy efficiency are proposed. • Road test results imply that the proposed parameters are effective. - Abstract: Comprehensive research is conducted on the design and control of a regenerative braking system for electric vehicles. The mechanism and evaluation methods of contribution brought by regenerative braking to improve electric vehicle’s energy efficiency are discussed and analyzed by the energy flow. Methodologies for calculating the contribution made by regenerative brake are proposed. Additionally a new regenerative braking control strategy called “serial 2 control strategy” is introduced. Moreover, two control strategies called “parallel control strategy” and “serial 1 control strategy” are proposed as the comparative control strategy. Furthermore, two different contribution ratio evaluation parameters according to the deceleration braking process are proposed. Finally, road tests are carried out under China typical city regenerative driving cycle standard with three different control strategies. The serial 2 control strategy offers considerably higher regeneration efficiency than the parallel strategy and serial 1 strategy.

Vibration control of an energy regenerative seat suspension with variable external resistance

Science.gov (United States)

Ning, Donghong; Sun, Shuaishuai; Du, Haiping; Li, Weihua; Zhang, Nong

2018-06-01

In this paper, an energy regenerative seat suspension with a variable external resistance is proposed and built, and a semi-active controller for its vibration control is also designed and validated. The energy regenerative seat suspension is built with a three-phase generator and a gear reducer, which are installed in the scissors structure centre of the seat suspension, and the vibration energy is directly harvested from the rotary movement of suspension's scissors structure. The electromagnetic torque of the semi-active seat suspension actuator is controlled by an external variable resistor. An integrated model including the seat suspension's kinematics and the generator is built and proven to match the test result very well. A simplified experimental phenomenon model is also built based on the test results for the controller design. A state feedback H∞ controller is proposed for the regenerative seat suspension's semi-active vibration control. The proposed regenerative seat suspension and its controller are validated with both simulations and experiments. A well-tuned passive seat suspension is applied to evaluate the regenerative seat's performance. Based on ISO 2631-1, the frequency-weighted root mean square (FW-RMS) acceleration of the proposed seat suspension has a 22.84% reduction when compared with the passive one, which indicates the improvement of ride comfort. At the same time, the generated RMS power is 1.21 W. The proposed regenerative seat suspension can greatly improve the driver's ride comfort and has the potential to be developed to a self-powered semi-active system.

Systems Analysis of Technologies for Energy Recovery from Waste. Part I. Gasification followed by Catalytic Combustion, PEM Fuel Cells and Solid Oxide Fuel Cells for Stationary Applications in Comparison with Incineration. Part - II. Catalytic combustion - Experimental part

Energy Technology Data Exchange (ETDEWEB)

Assefa, Getachew; Frostell, Bjoern [Royal Inst. of Technology, Stockholm (Sweden). Div. of Industrial Ecology; Jaeraas, Sven; Kusar, Henrik [Royal Inst. of Technology, Stockholm (Sweden). Div. of Chemical Technology

2005-02-01

This project is entitled 'Systems Analysis: Energy Recovery from waste, catalytic combustion in comparison with fuel cells and incineration'. Some of the technologies that are currently developed by researchers at the Royal Institute of Technology include catalytic combustion and fuel cells as downstream units in a gasification system. The aim of this project is to assess the energy turnover as well as the potential environmental impacts of biomass/waste-to-energy technologies. In second part of this project economic analyses of the technologies in general and catalytic combustion and fuel cell technologies in particular will be carried out. Four technology scenarios are studied: (1) Gasification followed by Low temperature fuel cells (Proton Exchange Membrane (PEM) fuel cells) (2) Gasification followed by high temperature fuel cells (Solid Oxide Fuel Cells (SOFC) (3) Gasification followed by catalytic combustion and (4) Incineration with energy recovery. The waste used as feedstock is an industrial waste containing parts of household waste, paper waste, wood residues and poly ethene. In the study compensatory district heating is produced by combustion of biofuel. The power used for running the processes in the scenarios will be supplied by the waste-to-energy technologies themselves while compensatory power is assumed to be produced from natural gas. The emissions from the system studied are classified and characterised using methodology from Life Cycle Assessment in to the following environmental impact categories: Global Warming Potential, Acidification Potential, Eutrophication Potential and finally Formation of Photochemical Oxidants. Looking at the result of the four technology chains in terms of the four impact categories with impact per GWh electricity produced as a unit of comparison and from the perspective of the rank each scenario has in all the four impact categories, SOFC appears to be the winner technology followed by PEM and CC as second

Systems Analysis of Technologies for Energy Recovery from Waste. Part I. Gasification followed by Catalytic Combustion, PEM Fuel Cells and Solid Oxide Fuel Cells for Stationary Applications in Comparison with Incineration. Part - II. Catalytic combustion - Experimental part

International Nuclear Information System (INIS)

Assefa, Getachew; Frostell, Bjoern; Jaeraas, Sven; Kusar, Henrik

2005-02-01

This project is entitled 'Systems Analysis: Energy Recovery from waste, catalytic combustion in comparison with fuel cells and incineration'. Some of the technologies that are currently developed by researchers at the Royal Institute of Technology include catalytic combustion and fuel cells as downstream units in a gasification system. The aim of this project is to assess the energy turnover as well as the potential environmental impacts of biomass/waste-to-energy technologies. In second part of this project economic analyses of the technologies in general and catalytic combustion and fuel cell technologies in particular will be carried out. Four technology scenarios are studied: (1) Gasification followed by Low temperature fuel cells (Proton Exchange Membrane (PEM) fuel cells) (2) Gasification followed by high temperature fuel cells (Solid Oxide Fuel Cells (SOFC) (3) Gasification followed by catalytic combustion and (4) Incineration with energy recovery. The waste used as feedstock is an industrial waste containing parts of household waste, paper waste, wood residues and poly ethene. In the study compensatory district heating is produced by combustion of biofuel. The power used for running the processes in the scenarios will be supplied by the waste-to-energy technologies themselves while compensatory power is assumed to be produced from natural gas. The emissions from the system studied are classified and characterised using methodology from Life Cycle Assessment in to the following environmental impact categories: Global Warming Potential, Acidification Potential, Eutrophication Potential and finally Formation of Photochemical Oxidants. Looking at the result of the four technology chains in terms of the four impact categories with impact per GWh electricity produced as a unit of comparison and from the perspective of the rank each scenario has in all the four impact categories, SOFC appears to be the winner technology followed by PEM and CC as second and third

Surgical Non-Regenerative Treatments for Peri-Implantitis: a Systematic Review

Directory of Open Access Journals (Sweden)

Ausra Ramanauskaite

2016-09-01

Full Text Available Objectives: The purposes of the present study were 1 to systematically review the literature on the surgical non-regenerative treatments of peri-implantitis and 2 to determine a predictable therapeutic option for the clinical management of peri-implantitis lesions. Material and Methods: The study search was performed on primary database MEDLINE and EMBASE from 2005 until 2016. Sequential screenings at the title, abstract, and full-text levels were performed. Clinical human studies in the English language that had reported changes in probing depth (PD and/or bleeding on probing (BOP and/or radiologic marginal bone level changes after peri-implantitis surgical non-regenerative treatment at 6-month follow-up or longer were included accordingly PRISMA guidelines. Results: The first electronic and hand search resulted in 765 citations. From 16 full-text articles reviewed, 6 were included in this systematic review. Surgical non-regenerative methods were found to be efficient in reducing clinical parameters. BOP and PD values were significantly decreased following implantoplasty and systematic administration of antibacterials, but not after local application of chemical compounds or diode laser. Similarly, significant improvement in clinical and radiographic parameters was found only after implantoplasty compared with resective surgery alone. We found significant heterogeneity in study designs and treatments provided among the pooled studies. All of the studies revealed an unclear or high risk of bias. Conclusions: Surgical non-regenerative treatment of peri-implantitis was found to be effective to reduce the soft tissue inflammation and decrease probing depth. More randomized controlled clinical trials are needed to assess the efficacy of surgical non-regenerative therapy of peri-implantitis.

Regenerative memory in time-delayed neuromorphic photonic resonators

Science.gov (United States)

Romeira, B.; Avó, R.; Figueiredo, José M. L.; Barland, S.; Javaloyes, J.

2016-01-01

We investigate a photonic regenerative memory based upon a neuromorphic oscillator with a delayed self-feedback (autaptic) connection. We disclose the existence of a unique temporal response characteristic of localized structures enabling an ideal support for bits in an optical buffer memory for storage and reshaping of data information. We link our experimental implementation, based upon a nanoscale nonlinear resonant tunneling diode driving a laser, to the paradigm of neuronal activity, the FitzHugh-Nagumo model with delayed feedback. This proof-of-concept photonic regenerative memory might constitute a building block for a new class of neuron-inspired photonic memories that can handle high bit-rate optical signals.

Preparation of the vulcan XC-72R-supported Pt nanoparticles for the hydrogen evolution reaction in PEM water electrolysers

International Nuclear Information System (INIS)

Nguyen, Huy Du; Nguyen, T Thuy Luyen; Nguyen, Khac Manh; Ha, Thuc Huy; Nguyen, Quoc Hien

2015-01-01

Pt nanoparticles on vulcan XC-72R support (Pt/vulcan XC-72R) were prepared by the impregnation–reduction method. The Pt content, the morphological properties and the electrochemical catalysis of the Pt/vulcan XC 72R materials have been investigated by ICP-OES analysis, FESEM, TEM, and cyclic voltammetry. These materials were then used as catalyst for hydrogen evolution reaction at the cathode of proton exchange membrane (PEM) water electrolysers. The best catalyst was Pt/vulcan XC-72R prepared by the impregnation–reduction method which is conducted in two reducing steps with the reductants of sodium borohydride and ethylene glycol, respectively. The current density of PEM water electrolysers reached 1.0 A cm"−"2 when applying a voltage of 2.0 V at 25 °C. (paper)

High Temperature PEM Fuel Cells and Organic Fuels

DEFF Research Database (Denmark)

Vassiliev, Anton

of the products. The observation of internal reforming was indirectly confirmed by electrochemical impedance spectroscopy, where the best fits were obtained when a Gerischer element describing preceding chemical reaction and diffusion was included in the equivalent circuit of a methanol/air operated cell...... evaporated liquid stream supply to either of the electrodes. A large number of MEAs with different component compositions have been prepared and tested in different conditions using the constructed setups to obtain a basic understanding of the nature of direct DME HT-PEM FC, to map the processes occurring...... inside the cells and to determine the lifetime. Additionally, comparison was made with methanol as fuel, which is the main competitor to DME in direct oxidation of organic fuels in fuel cells. For the reference, measurements have also been done with conventional hydrogen/air operation. All...

Regulators of pluripotency and their implications in regenerative medicine

Directory of Open Access Journals (Sweden)

El-Badawy A

2015-04-01

Full Text Available Ahmed El-Badawy, Nagwa El-Badri Center of Excellence for Stem Cells and Regenerative Medicine, Zewail City of Science and Technology, Giza, Egypt Abstract: The ultimate goal of regenerative medicine is to replace damaged tissues with new functioning ones. This can potentially be accomplished by stem cell transplantation. While stem cell transplantation for blood diseases has been increasingly successful, widespread application of stem cell therapy in the clinic has shown limited results. Despite successful efforts to refine existing methodologies and to develop better ones for reprogramming, clinical application of stem cell therapy suffers from issues related to the safety of the transplanted cells, as well as the low efficiency of reprogramming technology. Better understanding of the underlying mechanism(s involved in pluripotency should accelerate the clinical application of stem cell transplantation for regenerative purposes. This review outlines the main decision-making factors involved in pluripotency, focusing on the role of microRNAs, epigenetic modification, signaling pathways, and toll-like receptors. Of special interest is the role of toll-like receptors in pluripotency, where emerging data indicate that the innate immune system plays a vital role in reprogramming. Based on these data, we propose that nongenetic mechanisms for reprogramming provide a novel and perhaps an essential strategy to accelerate application of regenerative medicine in the clinic. Keywords: dedifferentiation, transdifferentiation, reprogramming, pluripotency, microRNAs, epigenetic modifications, signaling pathways, toll-like receptors

Validation of cell voltage and water content in a PEM (polymer electrolyte membrane) fuel cell model using neutron imaging for different operating conditions

International Nuclear Information System (INIS)

Salva, J. Antonio; Iranzo, Alfredo; Rosa, Felipe; Tapia, Elvira

2016-01-01

This work presents a one dimensional analytical model developed for a 50 cm"2 PEM (polymer electrolyte membrane) fuel cell with five-channel serpentine flow field. The different coupled physical phenomena such as electrochemistry, mass transfer of hydrogen, oxygen and water (two phases) together with heat transfer have been solved simultaneously. The innovation of this work is that the model has been validated with two different variables simultaneously and quantitatively in order to ensure the accuracy of the results. The selected variables are the cell voltage and the water content within the membrane MEA (Membrane Electrode Assembly) and GDL (gas diffusion layers) experimentally measured by means of neutron radiography. The results show a good agreement for a comprehensive set of different operating conditions of cell temperature, pressure, reactants relative humidity and cathode stoichiometry. The analytical model has a relative error less than 3.5% for the value of the cell voltage and the water content within the GDL + MEA for all experiments performed. This result presents a new standard of validation in the state of art of PEM fuel cell modeling where two variables are simultaneously and quantitatively validated with experimental results. The developed analytical model has been used in order to analyze the behavior of the PEM fuel cell under different values of relative humidity. - Highlights: • One dimensional analytical model has been developed for a PEM fuel cell. • The model is validated with two different variables simultaneously. • New standard of validation is proposed.

Nanotechnology and regenerative therapeutics in plastic surgery: The next frontier.

Science.gov (United States)

Tan, Aaron; Chawla, Reema; G, Natasha; Mahdibeiraghdar, Sara; Jeyaraj, Rebecca; Rajadas, Jayakumar; Hamblin, Michael R; Seifalian, Alexander M

2016-01-01

The rapid ascent of nanotechnology and regenerative therapeutics as applied to medicine and surgery has seen an exponential rise in the scale of research generated in this field. This is evidenced not only by the sheer volume of papers dedicated to nanotechnology but also in a large number of new journals dedicated to nanotechnology and regenerative therapeutics specifically to medicine and surgery. Aspects of nanotechnology that have already brought benefits to these areas include advanced drug delivery platforms, molecular imaging and materials engineering for surgical implants. Particular areas of interest include nerve regeneration, burns and wound care, artificial skin with nanoelectronic sensors and head and neck surgery. This study presents a review of nanotechnology and regenerative therapeutics, with focus on its applications and implications in plastic surgery. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. All rights reserved.

Pigmented Epithelioid Melanocytoma (PEM)/Animal Type Melanoma (ATM): Quest for an Origin. Report of One Unusual Case Indicating Follicular Origin and Another Arising in an Intradermal Nevus.

Science.gov (United States)

Tarasen, Ashley; Carlson, J Andrew; Leonard, M Kathryn; Merlino, Glenn; Kaetzel, David; Slominski, Andrzej T

2017-08-15

Pigmented epithelioid melanocytoma (PEM) is a tumor encompassing epithelioid blue nevus of Carney complex (EBN of CNC) and was previously termed animal-type melanoma. Histologically PEMs are heavily pigmented spindled and epithelioid dermal melanocytic tumors with infiltrative borders, however, their origin remains unclear. Stem cells for the epidermis and hair follicle are located in the bulge area of the hair follicle with the potential to differentiate into multiple lineages. Multiple cutaneous carcinomas, including follicular cutaneous squamous cell carcinoma (FSCC), are thought to arise from stem cells in the follicular bulge. We present two cases of PEM/ATM in a 63 year-old male on the scalp with follicular origin and a 72 year-old female on the upper back arising in an intradermal nevus. Biopsy of both cases revealed a proliferation of heavily pigmented dermal nests of melanocytes with atypia. The Case 1 tumor was in continuation with the outer root sheath of the hair follicle in the bulge region. Case 2 arose in an intradermal melanocytic nevus. Rare mitotic figures, including atypical mitotic figures, were identified in both cases. We present two cases of PEM, with histologic evidence suggesting two origins: one from the follicular bulb and one from an intradermal nevus.

Investigation on the corrosion resistance of PIM 316L stainless steel in PEM fuel cell simulated environment

International Nuclear Information System (INIS)

Oliveira, Mara Cristina Lopes de; Costa, Isolda; Antunes, Renato Altobelli

2009-01-01

Bipolar plates play main functions in PEM fuel cells, accounting for the most part of the weight and cost of these devices. Powder metallurgy may be an interesting manufacturing process of these components owing to the production of large scale, complex near-net shape parts. However, corrosion processes are a major concern due to the increase of the passive film thickness on the metal surface, lowering the power output of the fuel cell. In this work, the corrosion resistance of PIM AISI 316L stainless steel specimens was evaluated in 1M H 2 SO 4 + 2 ppm HF solution at room temperature during 30 days of immersion. The electrochemical measurements comprised potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology of the specimens was observed before and after the corrosion tests through SEM images. The material presented low corrosion current density suggesting that it is suitable to operate in the PEM fuel cell environment. (author)

Decarbonization by means of hydrogen; Dekarbonisierung mittels Wasserstoff

Energy Technology Data Exchange (ETDEWEB)

Kreutzer, Ulrich [Siemens AG, Muenchen (Germany). Research in Energy and Electronics, Corporate Technology

2018-01-15

Hydrogen electrolysis plays a crucial role in reducing CO{sub 2} emissions. With the help of regeneratively generated electricity, it converts water into its constituents hydrogen and oxygen without producing carbon dioxide. Experts are working on the still young PEM technology, which is particularly efficient and environmentally friendly. The holistic optimization of the plant plays an important role. [German] Wasserstoffelektrolyse spielt eine entscheidende Rolle, um CO{sub 2}-Emissionen einzudaemmen. Mit Hilfe regenerativ erzeugtem Strom wandelt sie Wasser in seine Bestandteile Wasserstoff und Sauerstoff um, ohne dass dabei Kohlenstoffdioxid entsteht. Experten arbeiten an der noch jungen PEM-Technologie, die besonders effizient und umweltvertraeglich ist. Eine wichtige Bedeutung hat dabei die ganzheitliche Optimierung der Anlage.

Design, Fabrication and Prototype testing of a Chip Integrated Micro PEM Fuel Cell Accumulator combined On-Board Range Extender

International Nuclear Information System (INIS)

Balakrishnan, A; Mueller, C; Reinecke, H

2014-01-01

In this work we present the design, fabrication and prototype testing of Chip Integrated Micro PEM Fuel Cell Accumulator (CIμ-PFCA) combined On-Board Range Extender (O-BRE). CIμ-PFCA is silicon based micro-PEM fuel cell system with an integrated hydrogen storage feature (palladium metal hydride), the run time of CIμ-PFCA is dependent on the stored hydrogen, and in order to extend its run time an O-BRE is realized (catalytic hydrolysis of chemical hydride, NaBH 4 . Combining the CIμ-PFCA and O-BRE on a system level have few important design requirements to be considered; hydrogen regulation, gas -liquid separator between the CIμ-PFCA and the O-RE. The usage of traditional techniques to regulate hydrogen (tubes), gas-liquid phase membranes (porous membrane separators) are less desirable in the micro domain, due to its space constraint. Our approach is to use a passive hydrogen regulation and gas-liquid phase separation concept; to use palladium membrane. Palladium regulates hydrogen by concentration diffusion, and its property to selectively adsorb only hydrogen is used as a passive gas-liquid phase separator. Proof of concept is shown by realizing a prototype system. The system is an assembly of CIμ-PFCA, palladium membrane and the O-BRE. The CIμ-PFCA consist of 2 individually processed silicon chips, copper supported palladium membrane realized by electroplating followed by high temperature annealing process under inter atmosphere and the O-BRE is realized out of a polymer substrate by micromilling process with platinum coated structures, which functions as a catalyst for the hydrolysis of NaBH 4 . The functionality of the assembled prototype system is demonstrated by the measuring a unit cell (area 1 mm 2 ) when driven by the catalytic hydrolysis of chemical hydride (NaBH 4 and the prototype system shows run time more than 15 hours

Hydrogen preheating through waste heat recovery of an open-cathode PEM fuel cell leading to power output improvement

International Nuclear Information System (INIS)

Mohamed, W.A.N.W.; Kamikl, M. Haziq M.

2016-01-01

Highlights: • A study on the effect of hydrogen preheating using waste heat for low temperature PEM fuel cells. • Theoretical, experimental and analytical framework was established. • The maximum electrical power output increases by 8–10% under specific operating conditions. • Open loop hydrogen supply gives a better performance than closed loop. • The waste heat utilization is less than 10% due to heat capacity limitations. - Abstract: The electrochemical reaction kinetics in a Polymer Electrolyte Membrane (PEM) fuel cell is highly influenced by the reactants supply pressures and electrode temperatures. For an open cathode PEM fuel cell stack, the power output is constrained due to the use of air simultaneously as reactant and coolant. Optimal stack operation temperatures are not achieved especially at low to medium power outputs. Based on the ideal gas law, higher reactant temperatures would lead to higher pressures and subsequently improve the reaction kinetics. The hydrogen supply temperature and its pressure can be increased by preheating; thus, slightly offsetting the limitation of low operating stack temperatures. The exit air stream offers an internal source of waste heat for the hydrogen preheating purpose. In this study, a PEM open-cathode fuel cell was used to experimentally evaluate the performance of hydrogen preheating based on two waste heat recovery approaches: (1) open-loop and (2) closed loop hydrogen flow. The stack waste heat was channelled into a heat exchanger to preheat the hydrogen line before it is being supplied (open loop) or resupplied (closed loop) into the stack. At a constant 0.3 bar hydrogen supply pressure, the preheating increases the hydrogen temperature in the range of 2–13 °C which was dependant on the stack power output and cathode air flow rates. The achievable maximum stack power was increased by 8% for the closed loop and 10% for the open loop. Due to the small hydrogen flow rates, the waste heat utilization

Using the multiple regression analysis with respect to ANOVA and 3D mapping to model the actual performance of PEM (proton exchange membrane) fuel cell at various operating conditions

International Nuclear Information System (INIS)

Al-Hadeethi, Farqad; Al-Nimr, Moh'd; Al-Safadi, Mohammad

2015-01-01

The performance of PEM (proton exchange membrane) fuel cell was experimentally investigated at three temperatures (30, 50 and 70 °C), four flow rates (5, 10, 15 and 20 ml/min) and two flow patterns (co-current and counter current) in order to generate two correlations using multiple regression analysis with respect to ANOVA. Results revealed that increasing the temperature for co-current and counter current flow patterns will increase both hydrogen and oxygen diffusivities, water management and membrane conductivity. The derived mathematical correlations and three dimensional mapping (i.e. surface response) for the co-current and countercurrent flow patterns showed that there is a clear interaction among the various variables (temperatures and flow rates). - Highlights: • Generating mathematical correlations using multiple regression analysis with respect to ANOVA for the performance of the PEM fuel cell. • Using the 3D mapping to diagnose the optimum performance of the PEM fuel cell at the given operating conditions. • Results revealed that increasing the flow rate had direct influence on the consumption of oxygen. • Results assured that increasing the temperature in co-current and counter current flow patterns increases the performance of PEM fuel cell.

Advanced regenerative heat recovery system

Science.gov (United States)

Prasad, A.; Jasti, J. K.

1982-02-01

A regenerative heat recovery system was designed and fabricated to deliver 1500 scfm preheated air to a maximum temperature of 1600 F. Since this system is operating at 2000 F, the internal parts were designed to be fabricated with ceramic materials. This system is also designed to be adaptable to an internal metallic structure to operate in the range of 1100 to 1500 F. A test facility was designed and fabricated to test this system. The test facility is equipped to impose a pressure differential of up to 27 inches of water column in between preheated air and flue gas lines for checking possible leakage through the seals. The preliminary tests conducted on the advanced regenerative heat recovery system indicate the thermal effectiveness in the range of 60% to 70%. Bench scale studies were conducted on various ceramic and gasket materials to identify the proper material to be used in high temperature applications. A market survey was conducted to identify the application areas for this heat recovery system. A cost/benefit analysis showed a payback period of less than one and a half years.

Nonlinear Modeling and Coordinate Optimization of a Semi-Active Energy Regenerative Suspension with an Electro-Hydraulic Actuator

Directory of Open Access Journals (Sweden)

Farong Kou

2018-01-01

Full Text Available In order to coordinate the damping performance and energy regenerative performance of energy regenerative suspension, this paper proposes a structure of a vehicle semi-active energy regenerative suspension with an electro-hydraulic actuator (EHA. In light of the proposed concept, a specific energy regenerative scheme is designed and a mechanical properties test is carried out. Based on the test results, the parameter identification for the system model is conducted using a recursive least squares algorithm. On the basis of the system principle, the nonlinear model of the semi-active energy regenerative suspension with an EHA is built. Meanwhile, linear-quadratic-Gaussian control strategy of the system is designed. Then, the influence of the main parameters of the EHA on the damping performance and energy regenerative performance of the suspension is analyzed. Finally, the main parameters of the EHA are optimized via the genetic algorithm. The test results show that when a sinusoidal is input at the frequency of 2 Hz and the amplitude of 30 mm, the spring mass acceleration root meam square value of the optimized EHA semi-active energy regenerative suspension is reduced by 22.23% and the energy regenerative power RMS value is increased by 40.51%, which means that while meeting the requirements of vehicle ride comfort and driving safety, the energy regenerative performance is improved significantly.

Thermo-economic optimization of Regenerative Organic Rankine Cycle for waste heat recovery applications

International Nuclear Information System (INIS)

Imran, Muhammad; Park, Byung Sik; Kim, Hyouck Ju; Lee, Dong Hyun; Usman, Muhammad; Heo, Manki

2014-01-01

Highlights: • Thermo-economic optimization of regenerative ORC is performed. • Optimization is performed using multi objective genetic algorithm. • Objective function is maximum cycle efficiency and minimum specific investment. • Evaporation pressure, pinch point and superheat are decision variables. • Sensitivity analysis is performed to investigate effect of decision variables. - Abstract: Organic Rankine Cycle (ORC) is low grade and waste heat conversion technology. The current article deal with the thermo-economic optimization of basic ORC and regenerative ORC for waste heat recovery applications under constant heat source condition. Thermal efficiency and specific investment cost of basic ORC, single stage regenerative and double stage regenerative ORC has been optimized by using Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Maximum thermal efficiency and minimum specific investment cost were selected as objective functions and relative increase in thermal efficiency and cost has been analyzed taking the basic ORC as base case. The constraint set consist of evaporation pressure, superheat, pinch point temperature difference in evaporator and condenser. The optimization was performed for five different working fluids. The optimization result show that R245fa is best working under considered conditions and basic ORC has low specific investment cost and thermal efficiency compared to regenerative ORC. R245fa is low boiling organic fluid, which has high degree of thermal stability and compatible with common construction materials of ORC. The average increase in thermal efficiency from basic ORC to single stage regenerative ORC was 1.01% with an additional cost of 187 $/kW while from basic ORC to double stage regenerative ORC was 1.45% with an average increase in cost of 297 $/kW. The sensitivity analysis was also performed to investigate the effect of operating conditions which show that evaporation pressure has promising effect on thermal

Device for processing regenerative wastes of ion exchange resin

International Nuclear Information System (INIS)

Kuroda, Osamu; Ebara, Katsuya; Shindo, Toshikazu; Takahashi, Sankichi

1986-01-01

Purpose: To facilitate the operation and maintenance of a processing device by dividing radioactive wastes produced in the regenerative process of ion exchange resin into a regenerated usable recovery liquid and wastes. Constitution: Sulfuric acid is recovered by a diffusion dialysis method from wastes containing sulfuric acid that are generated in the regenerative process of cation-exchange resin and also caustic soda is recovered by the diffusion dialysis method from wastes containing caustic soda that are generated in the regenerative process of anion-exchange resin. The sulfuric acid and caustic soda thus recovered are used for the regeneration of ion-exchange resin. A concentrator is provided for concentrating the sulfuric acid and caustic soda water solution to concentration suitable for the regeneration of these ion-exchange resins. Also provided is a recovery device for recovering water generated from the concentrator. This device is of so simple a constitution that its operation and maintenance can be performed very easily, thereby greatly reducing the quantity of waste liquid required to be stored in drums. (Takahashi, M.)

Regenerative Medicine Applications in Wound Care.

Science.gov (United States)

Nilforoushzadeh, Mohammad Ali; Sisakht, Mahsa Mollapour; Seifalian, Alexander Marcus; Amirkhani, Mohammad Amir; Banafshe, Hamid Reza; Verdi, Javad; Sharifzad, Farzaneh; Taghiabadi, Ehsan

2017-01-01

During the last two decades, a number of studies have been carried out on the application of regenerative medicine in the field of dermatology. The aim of this research was to critically review the application of regenerative medicine in the field of dermatology. The next aim was to look in depth to see whether regenerative medicine strategies have a place in the future of wound healing in a clinical setting. More specifically, to see if these strategies would apply for burns and non-healing diabetic wounds. Billions of dollars have been spent worldwide on research in wound treatment and skin regeneration. Although a high number of clinical trials show promising results, there is still no commercially available treatment for use. In addition, the outcome data from the clinical trials, taking place throughout the world, are not published in a standardized manner. Standardization within clinical trials is required for: protocols, outcome, endpoint values, and length of follow-up. The lack of standardization makes it much more difficult to compare the data collected and the different types of treatment. Despite several promising results from research and early phase clinical studies, the treatment for wounds as well as skin regeneration is still considered as an unmet clinical need. However, in the past three years, more promising research has been approaching clinical trials; this could be the solution that clinicians have been waiting for. This is a multibillion dollar industry for which there should be enough incentive for researchers and industry to seek the solution. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Accelerating regenerative medicine: the Japanese experiment in ethics and regulation.

Science.gov (United States)

Lysaght, Tamra

2017-09-01

In 2014, the Japanese National Diet introduced new laws aimed at promoting the clinical translation of stem cells and regenerative medicine. The basic action of these laws is to allow the early introduction of regenerative medicine products into the Japanese market through an accelerated approval process, while providing patients with access to certain types of stem cell and cell-based therapies in the context of private clinical practice. While this framework appears to offer enormous opportunities for the translation of stem cell science, it raises ethical challenges that have not yet been fully explored. This paper critically analyzes this framework with respect to the prioritization of safety over clinical benefit, distributive justice and public trust in science and medicine. It is argued that the framework unfairly burdens patients and strained healthcare systems without any clear benefits, and may undermine the credibility of the regenerative medicine field as it emerges.

Developing a pro-regenerative biomaterial scaffold microenvironment requires T helper 2 cells.

Science.gov (United States)

Sadtler, Kaitlyn; Estrellas, Kenneth; Allen, Brian W; Wolf, Matthew T; Fan, Hongni; Tam, Ada J; Patel, Chirag H; Luber, Brandon S; Wang, Hao; Wagner, Kathryn R; Powell, Jonathan D; Housseau, Franck; Pardoll, Drew M; Elisseeff, Jennifer H

2016-04-15

Immune-mediated tissue regeneration driven by a biomaterial scaffold is emerging as an innovative regenerative strategy to repair damaged tissues. We investigated how biomaterial scaffolds shape the immune microenvironment in traumatic muscle wounds to improve tissue regeneration. The scaffolds induced a pro-regenerative response, characterized by an mTOR/Rictor-dependent T helper 2 pathway that guides interleukin-4-dependent macrophage polarization, which is critical for functional muscle recovery. Manipulating the adaptive immune system using biomaterials engineering may support the development of therapies that promote both systemic and local pro-regenerative immune responses, ultimately stimulating tissue repair. Copyright © 2016, American Association for the Advancement of Science.

Adipose-derived mesenchymal stem cells and regenerative medicine.

Science.gov (United States)

Konno, Masamitsu; Hamabe, Atsushi; Hasegawa, Shinichiro; Ogawa, Hisataka; Fukusumi, Takahito; Nishikawa, Shimpei; Ohta, Katsuya; Kano, Yoshihiro; Ozaki, Miyuki; Noguchi, Yuko; Sakai, Daisuke; Kudoh, Toshihiro; Kawamoto, Koichi; Eguchi, Hidetoshi; Satoh, Taroh; Tanemura, Masahiro; Nagano, Hiroaki; Doki, Yuichiro; Mori, Masaki; Ishii, Hideshi

2013-04-01

Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent and can differentiate into various cell types, including osteocytes, adipocytes, neural cells, vascular endothelial cells, cardiomyocytes, pancreatic β-cells, and hepatocytes. Compared with the extraction of other stem cells such as bone marrow-derived mesenchymal stem cells (BMSCs), that of ADSCs requires minimally invasive techniques. In the field of regenerative medicine, the use of autologous cells is preferable to embryonic stem cells or induced pluripotent stem cells. Therefore, ADSCs are a useful resource for drug screening and regenerative medicine. Here we present the methods and mechanisms underlying the induction of multilineage cells from ADSCs. © 2013 The Authors Development, Growth & Differentiation © 2013 Japanese Society of Developmental Biologists.

Regenerative Endodontic Treatment of a Maxillary Mature Premolar

Directory of Open Access Journals (Sweden)

Qingan Xu

2018-01-01

Full Text Available Regenerative endodontic treatment was performed on a mature maxillary premolar diagnosed as chronic pulpitis. The root canals were chemomechanically prepared and placed intracanal medicaments at the first appointment. Then 2 weeks later, a blood clot was created in the canals, over which mineral trioxide aggregate was placed. At 6-month follow-up, cementum-like tissue seemed to be formed in the root canal along with nearly recovered pulp vitality. At 12-month recall, the radiographic results revealed evidence of root wall thickening. At 30-month recall, no periapical lesion was found. This case report indicates that regenerative endodontic treatment for the mature premolar is feasible. More cases are needed for further validation.

Sparse QSAR modelling methods for therapeutic and regenerative medicine

Science.gov (United States)

Winkler, David A.

2018-02-01

The quantitative structure-activity relationships method was popularized by Hansch and Fujita over 50 years ago. The usefulness of the method for drug design and development has been shown in the intervening years. As it was developed initially to elucidate which molecular properties modulated the relative potency of putative agrochemicals, and at a time when computing resources were scarce, there is much scope for applying modern mathematical methods to improve the QSAR method and to extending the general concept to the discovery and optimization of bioactive molecules and materials more broadly. I describe research over the past two decades where we have rebuilt the unit operations of the QSAR method using improved mathematical techniques, and have applied this valuable platform technology to new important areas of research and industry such as nanoscience, omics technologies, advanced materials, and regenerative medicine. This paper was presented as the 2017 ACS Herman Skolnik lecture.

Optimization Design of Bipolar Plate Flow Field in PEM Stack

Science.gov (United States)

Wen, Ming; He, Kanghao; Li, Peilong; Yang, Lei; Deng, Li; Jiang, Fei; Yao, Yong

2017-12-01

A new design of bipolar plate flow field in proton exchange membrane (PEM) stack was presented to develop a high-performance transfer efficiency of the two-phase flow. Two different flow fields were studied by using numerical simulations and the performance of the flow fields was presented. the hydrodynamic properties include pressure gap between inlet and outlet, the Reynold’s number of the two types were compared based on the Navier-Stokes equations. Computer aided optimization software was implemented in the design of experiments of the preferable flow field. The design of experiments (DOE) for the favorable concept was carried out to study the hydrodynamic properties when changing the design parameters of the bipolar plate.

Recommendations for using regenerative endodontic procedures in permanent immature traumatized teeth.

Science.gov (United States)

Garcia-Godoy, Franklin; Murray, Peter E

2012-02-01

The regeneration of immature permanent teeth following trauma could be beneficial to reduce the risk of fracture and loss of millions of teeth each year. Regenerative endodontic procedures include revascularization, partial pulpotomy, and apexogenesis. Several case reports give these procedures a good prognosis as an alternative to apexification. Care is needed to deliver regenerative endodontic procedures that maintain or restore the vitality of teeth, but which also disinfect and remove necrotic tissues. Regeneration can be accomplished through the activity of the cells from the pulp, periodontium, vascular, and immune system. Most therapies use the host's own pulp or vascular cells for regeneration, but other types of dental stem cell therapies are under development. There are no standardized treatment protocols for endodontic regeneration. The purpose of this article is to review the recent literature and suggest guidelines for using regenerative endodontic procedures for the treatment of permanent immature traumatized teeth. Recommendations for the selection of regenerative and conventional procedures based on the type of tooth injury, fracture type, presence of necrosis or infection, periodontal status, presence of periapical lesions, stage of tooth development, vitality status, patient age, and patient health status will be reviewed. Because of the lack of long-term evidence to support the use of regenerative endodontic procedures in traumatized teeth with open apices, revascularization regeneration procedures should only be attempted if the tooth is not suitable for root canal obturation, and after apexogenesis, apexification, or partial pulpotomy treatments have already been attempted and have a poor prognosis. © 2011 John Wiley & Sons A/S.

Current density distribution mapping in PEM fuel cells as an instrument for operational measurements

Energy Technology Data Exchange (ETDEWEB)

Geske, M.; Heuer, M.; Heideck, G.; Styczynski, Z. A. [Otto-von-Guericke University Magdeburg, Chair Electric Power Networks and Renewable Energy Sources, Magdeburg (Germany)

2010-07-01

A newly developed measurement system for current density distribution mapping has enabled a new approach for operational measurements in proton exchange membrane fuel cells (PEMFC). Taking into account previously constructed measurement systems, a method based on a multi layer printed circuit board was chosen for the development of the new system. This type of system consists of a sensor, a special electronic device and the control and visualization PC. For the acquisition of the current density distribution values, a sensor device was designed and installed within a multilayer printed circuit board with integrated shunt resistors. Varying shunt values can be taken into consideration with a newly developed and evaluated calibration method. The sensor device was integrated in a PEM fuel cell stack to prove the functionality of the whole measurement system. A software application was implemented to visualize and save the measurement values. Its functionality was verified by operational measurements within a PEMFC system. Measurement accuracy and possible negative reactions of the sensor device during PEMFC operation are discussed in detail in this paper. The developed system enables operational measurements for different operating phases of PEM fuel cells. Additionally, this can be seen as a basis for new opportunities of optimization for fuel cell design and operation modes. (author)

Current Density Distribution Mapping in PEM Fuel Cells as An Instrument for Operational Measurements

Directory of Open Access Journals (Sweden)

Martin Geske

2010-04-01

Full Text Available A newly developed measurement system for current density distribution mapping has enabled a new approach for operational measurements in proton exchange membrane fuel cells (PEMFC. Taking into account previously constructed measurement systems, a method based on a multi layer printed circuit board was chosen for the development of the new system. This type of system consists of a sensor, a special electronic device and the control and visualization PC. For the acquisition of the current density distribution values, a sensor device was designed and installed within a multilayer printed circuit board with integrated shunt resistors. Varying shunt values can be taken into consideration with a newly developed and evaluated calibration method. The sensor device was integrated in a PEM fuel cell stack to prove the functionality of the whole measurement system. A software application was implemented to visualize and save the measurement values. Its functionality was verified by operational measurements within a PEMFC system. Measurement accuracy and possible negative reactions of the sensor device during PEMFC operation are discussed in detail in this paper. The developed system enables operational measurements for different operating phases of PEM fuel cells. Additionally, this can be seen as a basis for new opportunities of optimization for fuel cell design and operation modes.

A full Monte Carlo simulation of the YAP-PEM prototype for breast tumor detection

Science.gov (United States)

Motta, A.; Righi, S.; Del Guerra, A.; Belcari, N.; Vaiano, A.; De Domenico, G.; Zavattini, G.; Campanini, R.; Lanconelli, N.; Riccardi, A.

2004-07-01

A prototype for Positron Emission Mammography, the YAP-PEM, is under development within a collaboration of the Italian Universities of Pisa, Ferrara, and Bologna. The aim is to detect breast lesions, with dimensions of 5 mm in diameter, and with a specific activity ratio of 10:1 between the cancer and breast tissue. The YAP-PEM is composed of two stationary detection heads of 6×6 cm 2, composed of a matrix of 30×30 YAP:Ce finger crystals of 2×2×30 mm 3 each. The EGSnrc Monte Carlo code has been used to simulate several characteristics of the prototype. A fast EM algorithm has been adapted to reconstruct all of the collected lines of flight, also at large incidence angles, by achieving 3D positioning capability of the lesion in the FOV. The role of the breast compression has been studied. The performed study shows that a 5 mm diameter tumor of 37 kBq/cm 3 (1 μCi/cm 3), embedded in active breast tissue with 10:1 tumor/background specific activity ratio, is detected in 10 min with a Signal-to-Noise Ratio of 8.7±1.0. Two hot lesions in the active breast phantom are clearly visible in the reconstructed image.

Maximum Safety Regenerative Power Tracking for DC Traction Power Systems

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Guifu Du

2017-02-01

Full Text Available Direct current (DC traction power systems are widely used in metro transport systems, with running rails usually being used as return conductors. When traction current flows through the running rails, a potential voltage known as “rail potential” is generated between the rails and ground. Currently, abnormal rises of rail potential exist in many railway lines during the operation of railway systems. Excessively high rail potentials pose a threat to human life and to devices connected to the rails. In this paper, the effect of regenerative power distribution on rail potential is analyzed. Maximum safety regenerative power tracking is proposed for the control of maximum absolute rail potential and energy consumption during the operation of DC traction power systems. The dwell time of multiple trains at each station and the trigger voltage of the regenerative energy absorbing device (READ are optimized based on an improved particle swarm optimization (PSO algorithm to manage the distribution of regenerative power. In this way, the maximum absolute rail potential and energy consumption of DC traction power systems can be reduced. The operation data of Guangzhou Metro Line 2 are used in the simulations, and the results show that the scheme can reduce the maximum absolute rail potential and energy consumption effectively and guarantee the safety in energy saving of DC traction power systems.

Design and Control of High Temperature PEM Fuel Cell Systems using Methanol Reformers with Air or Liquid Heat Integration

DEFF Research Database (Denmark)

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

2013-01-01

The present work describes the ongoing development of high temperature PEM fuel cell systems fuelled by steam reformed methanol. Various fuel cell system solutions exist, they mainly differ depending on the desired fuel used. High temperature PEM (HTPEM) fuel cells offer the possibility of using...... methanol is converted to a hydrogen rich gas with CO2 trace amounts of CO, the increased operating temperatures allow the fuel cell to tolerate much higher CO concentrations than Nafion-based membranes. The increased tolerance to CO also enables the use of reformer systems with less hydrogen cleaning steps...... liquid fuels such as methanol, due to the increased robustness of operating at higher temperatures (160-180oC). Using liquid fuels such as methanol removes the high volume demands of compressed hydrogen storages, simplifies refueling, and enables the use of existing fuel distribution systems. The liquid...

An animal model to study regenerative endodontics.

Science.gov (United States)

Torabinejad, Mahmoud; Corr, Robert; Buhrley, Matthew; Wright, Kenneth; Shabahang, Shahrokh

2011-02-01

A growing body of evidence is demonstrating the possibility for regeneration of tissues within the pulp space and continued root development in teeth with necrotic pulps and open apices. There are areas of research related to regenerative endodontics that need to be investigated in an animal model. The purpose of this study was to investigate ferret cuspid teeth as a model to investigate factors involved in regenerative endodontics. Six young male ferrets between the ages of 36-133 days were used in this investigation. Each animal was anesthetized and perfused with 10% buffered formalin. Block sections including the mandibular and maxillary cuspid teeth and their surrounding periapical tissues were obtained, radiographed, decalcified, sectioned, and stained with hematoxylin-eosin to determine various stages of apical closure in these teeth. The permanent mandibular and maxillary cuspid teeth with open apices erupted approximately 50 days after birth. Initial signs of closure of the apical foramen in these teeth were observed between 90-110 days. Complete apical closure was observed in the cuspid teeth when the animals were 133 days old. Based on the experiment, ferret cuspid teeth can be used to investigate various factors involved in regenerative endodontics that cannot be tested in human subjects. The most appropriate time to conduct the experiments would be when the ferrets are between the ages of 50 and 90 days. Copyright © 2011. Published by Elsevier Inc.

Regenerative laser system

International Nuclear Information System (INIS)

Biancardi, F.R.; Landerman, A.; Melikian, G.

1975-01-01

Regenerative apparatus for exhausting the working medium from the optical cavity of a laser and for supplying preheated diluent to the reaction chamber of a laser is disclosed. In an aftercooler thermal energy is exchanged between the working medium exhausted from the optical cavity and a cryogenic coolant which is subsequently utilized as the motive fluid for an ejector and as a diluent in the production of laser gas. Highly toxic and corrosive gases are condensed out of the working medium as the cryogenic coolant is evaporated and superheated. A preheater transfers additional heat to the diluent before the diluent enters the reaction chamber. (U.S.)

Regenerative endodontics and tissue engineering: what the future holds?

Science.gov (United States)

Goodis, Harold E; Kinaia, Bassam Michael; Kinaia, Atheel M; Chogle, Sami M A

2012-07-01

The work performed by researchers in regenerative endodontics and tissue engineering over the last decades has been superb; however, many questions remain to be answered. The basic biologic mechanisms must be elucidated that will allow the development of dental pulp and dentin in situ. Stress must be placed on the many questions that will lead to the design of effective, safe treatment options and therapies. This article discusses those questions, the answers to which may become the future of regenerative endodontics. The future remains bright, but proper support and patience are required. Copyright © 2012 Elsevier Inc. All rights reserved.

Investigation of the purging effect on a dead-end anode PEM fuel cell-powered vehicle during segments of a European driving cycle

International Nuclear Information System (INIS)

Gomez, Alberto; Sasmito, Agus P.; Shamim, Tariq

2015-01-01

Highlights: • Experimental study of a dead-end anode PEM fuel cell stack during a driving cycle. • Low purging duration is preferred at high current. • High purging frequency can sustain a better performance over time. • Lower cathode stoichiometry is preferred to minimize the parasitic loads. - Abstract: The dynamic performance of the PEM fuel cell is one of the key factors for successful operation of a fuel cell-powered vehicle. Maintaining fast time response while keeping stable and high stack performance is of importance, especially during acceleration and deceleration. In this paper, we evaluate the transient response of a PEM fuel cell stack with a dead-end anode during segments of a legislated European driving cycle together with the effect of purging factors. The PEM fuel cell stack comprises of 24 cells with a 300 cm"2 active catalyst area and operates at a low hydrogen and air pressure. Humidified air is supplied to the cathode side and the dry hydrogen is fed to the anode. The liquid coolant is circulated to the stack and the radiator to maintain the thermal envelope throughout the stack. The stack performance deterioration over time is prevented by utilizing the purging, which removes the accumulated water and impurities. The effect of purging period, purging duration, coolant flow rate and cathode stoichiometry are examined with regard to the fuel cell’s transient performance during the driving cycle. The results show that a low purging duration may avoid the undesired deceleration at a high current, and a high purging period may sustain a better performance over time. Moreover, the coolant flow rate is found to be an important parameter, which affects the stack temperature–time response of the cooling control and the stack performance, especially at high operating currents.

Stem cells and the future of regenerative medicine

National Research Council Canada - National Science Library

National Research Council, Committee on the Biological and Biomedical Applications of Stem Cell Research; Commission on Life Sciences; National Research Council; Board on Life Sciences; Board on Neuroscience and Behavioral Health; Division on Earth and Life Studies; Institute of Medicine

2002-01-01

.... Stem Cells and the Future of Regenerative Medicine provides a deeper exploration of the biological, ethical, and funding questions prompted by the therapeutic potential of undifferentiated human cells...

Electro-activity of cobalt and nickel complexes for the reduction of protons into di-hydrogen. Application to PEM water electrolysis

International Nuclear Information System (INIS)

Pantani, O.; Anxolabehere, E.; Aukauloo, A.; Millet, P.

2006-01-01

Proton exchange membrane (PEM) water electrolysis is a safe and efficient way to perform water splitting into di-hydrogen and di-oxygen. In a PEM water electrolyser, platinum is commonly used as electro-catalyst on the cathodic side of the cells, mostly because of its efficiency for hydrogen evolution. But for cost considerations, there is a need to find alternative low-cost electrocatalysts. Molecular chemistry offers the possibility of synthesizing new compounds for this purpose, such as transition metal complexes. Results obtained with nickel- and cobalt-oximes compounds are presented in this paper. They have been chemically (1H NMR, EPR) and electrochemically (voltametry, spectro-electrochemistry) characterized. Their ability to electrochemically reduce protons into di-hydrogen when they are either dissolved in solution or immobilized at the surface of a solid electrode is discussed. (authors)

Optimization of the alignment sensitivity and energy stability of the NIF regenerative amplifier cavity

International Nuclear Information System (INIS)

Hopps, N. W.

1998-01-01

The work to improve the energy stability of the regenerative amplifier ('regen') for the National Ignition Facility is described. This includes a fast feed-forward system, designed to regulate the output energy of the regen by monitoring how quickly a pulse builds up over many round trips. Shot-to-shot energy fluctuations of all elements prior to (and including) the regen may be compensated for in this way, at the expense of a loss of approximately 50%. Also included is a detailed study into the alignment sensitivity of the regen cavity, with the goal of quantifying the effect of misalignment on the output energy. This is done by calculating the displacement of the eigenmode by augmenting the cavity ABCD matrix with the misalignment matrix elements, E, F. In this way, cavity misalignment issues due to thermal loading of the gain medium are investigated. Alternative cavity designs, which reduce the alignment sensitivity and therefore the energy drift over periods of continuous operation, are considered. Alterations to the amplifier head design are also considered

Adaptation and validation of the REGEN expert system for the Central Appalachians

Science.gov (United States)

Lance A. Vickers; Thomas R. Fox; David L. Loftis; David A. Boucugnani

2011-01-01

REGEN is an expert system that predicts future species composition at the onset of stem exclusion using preharvest stand conditions. To extend coverage into hardwood stands of the Central Appalachians, we developed REGEN knowledge bases for four site qualities (xeric, subxeric, submesic, mesic) based on relevant literature and expert opinion. Data were collected from...

Predicting Forest Regeneration in the Central Appalachians Using the REGEN Expert System

Science.gov (United States)

Lance A. Vickers; Thomas R. Fox; David L. Loftis; David A. Boucugnani

2011-01-01

REGEN is an expert system designed by David Loftis to predict the future species composition of dominant and codominant stems in forest stands at the onset of stem exclusion following a proposed harvest. REGEN predictions are generated using competitive rankings for advance reproduction along with other existing stand conditions. These parameters are contained within...

Exploiting the Bioactive Properties of the Dentin-Pulp Complex in Regenerative Endodontics.

Science.gov (United States)

Smith, Anthony J; Duncan, Henry F; Diogenes, Anibal; Simon, Stephane; Cooper, Paul R

2016-01-01

The development of regenerative endodontic therapies offers exciting opportunities for future improvements in treatment outcomes. Advances in our understanding of regenerative events at the molecular and cellular levels are helping to underpin development of these therapies, although the various strategies differ in the translational challenges they pose. The identification of a variety of bioactive molecules, including growth factors, cytokines, chemokines, and matrix molecules, sequestered within dentin and dental pulp provides the opportunity to present key signaling molecules promoting reparative and regenerative events after injury. The protection of the biological activity of these molecules by mineral in dentin before their release allows a continuing supply of these molecules, while avoiding the short half-life and the non-human origin of exogenous molecules. The ready release of these bioactive molecules by the various tissue preparation agents, medicaments, and materials commonly used in endodontics highlights the opportunities for translational regenerative strategies exploiting these molecules with little change to existing clinical practice. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Enhanced Regenerative Braking Strategies for Electric Vehicles: Dynamic Performance and Potential Analysis

Directory of Open Access Journals (Sweden)

Boyi Xiao

2017-11-01

Full Text Available A regenerative braking system and hydraulic braking system are used in conjunction in the majority of electric vehicles worldwide. We propose a new regenerative braking distribution strategy that is based on multi-input fuzzy control logic while considering the influences of the battery’s state of charge, the brake strength and the motor speed. To verify the braking performance and recovery economy, this strategy was applied to a battery electric vehicle model and compared with two other improved regenerative braking strategies. The performance simulation was performed using standard driving cycles (NEDC, LA92, and JP1015 and a real-world-based urban cycle in China. The tested braking strategies satisfied the general safety requirements of Europe (as specified in ECE-13H, and the emergency braking scenario and economic potential were tested. The simulation results demonstrated the differences in the braking force distribution performance of these three regenerative braking strategies, the feasibility of the braking methods for the proposed driving cycles and the energy economic potential of the three strategies.

Feasibility of implementation of an autonomous hybrid system for PEM fuel cells to electrify localities in rural Cuba; Factibilidad de implementacion de un sistema hibrido autonomo con celda de combustible PEM para electrificar localidades rurales en Cuba

Energy Technology Data Exchange (ETDEWEB)

Sanchez Torres, Yamir [Centro de Estudios de Tecnologias Energeticas Renovables (CETER), Ciudad de la Habana (Cuba)] e-mail: yamir@ceter.cujae.edu.cu

2009-09-15

The use of PEM fuel cells to produce electric energy in autonomous systems is closely linked with the production and storage of hydrogen. Eventually joined with sources of renewable energy, this creates an ecologically clean and sustainable system. In several developing countries, localities exist that do not have electricity but have significant unexploited renewable energy power, where an autonomous hybrid system can be designed to electrify these population centers. This work presents a hybrid electricity scheme with a PEM fuel cell to produce hydrogen and electricity in order to electrify rural zones far from the national power grid in Cuba. The electric demand of the zone and available energy power was calculated using the informatics modeling and simulation programs HOMER, PVSYST and Matlab 1,2,3. Variability in wind and photovoltage power was determined based on daylight hours and seasonal periods throughout the year as well as their effect on the production of hydrogen and electricity. It was shown that the energy demand is met even for the most adverse scenarios. This work offers a detailed description of the behavior of the system and evidence of no effect on the environment, enabling the electrification and wellbeing of residents of the locality. [Spanish] El uso de celdas de combustible PEM para la produccion de energia electrica en sistemas autonomos esta estrechamente ligado a la produccion y almacenamiento de hidrogeno. Esto eventualmente unido a las fuentes renovables de energia forma un sistema ecologicamente limpio y sustentable. En varios paises subdesarrollados existen localidades que no cuentan con electricidad y que tienen importantes potenciales energeticos renovables no explotados actualmente en los cuales se puede disenar un sistema hibrido autonomo para electrificar estas poblaciones. En este trabajo se presenta el esquema de un sistema hibrido autonomo con celda de combustible PEM, para la produccion de hidrogeno y electricidad encaminado

Regenerative endodontics: a true paradigm shift or a bandwagon about to be derailed?

Science.gov (United States)

Nazzal, H; Duggal, M S

2017-02-01

Regenerative endodontic techniques (RETs) have been hailed as a paradigm shift for the management of traumatised non-vital immature permanent anterior teeth. In this article the aim was to critically appraise the literature with regards to the outcome of regenerative endodontics on root development. Critical review of the literature where regenerative endodontic techniques have been used in the management of immature non-vital teeth with continuation of root development as the main outcome reported. Most studies published were in the form of case reports and series with very few randomised controlled trials with a high risk of bias. Continuation of root development following the use of RET has been shown to be unpredictable at best with lower success in those teeth losing vitality as a result of dental trauma. Despite the high success of regenerative endodontics in terms of periodontal healing including resolution of clinical and radiographic signs and symptoms of infection, continuation of root development remains an unpredictable outcome. The use of a blood clot as a scaffold in regenerative endodontics should be reviewed carefully as that might offer an environment for repair rather than regeneration. In addition, preservation of structures, such as Hertwig's epithelial root sheath, may have an important bearing on the success of this approach and should be further investigated.

Clear-PEM: A PET imaging system dedicated to breast cancer diagnostics

CERN Document Server

Abreu, M C; Albuquerque, E; Almeida, F G; Almeida, P; Amaral, P; Auffray, Etiennette; Bento, P; Bruyndonckx, P; Bugalho, R; Carriço, B; Cordeiro, H; Ferreira, M; Ferreira, N C; Gonçalves, F; Lecoq, Paul; Leong, C; Lopes, F; Lousã, P; Luyten, J; Martins, M V; Matela, N; Rato-Mendes, P; Moura, R; Nobre, J; Oliveira, N; Ortigão, C; Peralta, L; Rego, J; Ribeiro, R; Rodrigues, P; Santos, A I; Silva, J C; Silva, M M; Tavernier, Stefaan; Teixeira, I C; Texeira, J P; Trindade, A; Trummer, Julia; Varela, J

2007-01-01

The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A specialized gantry allows to perform exams of the breast and of the axilla. In this paper we present results of the measurement of detector modules that integrate the system under construction as well as the imaging performance estimated from Monte Carlo simulated data.

Corrosion of metal bipolar plates for PEM fuel cells: A review

Energy Technology Data Exchange (ETDEWEB)

Antunes, Renato A. [Engenharia de Materiais, Universidade Federal do ABC (UFABC), 09210-170 Santo Andre, SP (Brazil); Oliveira, Mara Cristina L.; Ett, Gerhard; Ett, Volkmar [Electrocell Ind. Com. Equip. Elet. LTDA, Centro de Inovacao, Empreendedorismo e Tecnologia (CIETEC), 05508-000 Sao Paulo, SP (Brazil)

2010-04-15

PEM fuel cells are of prime interest in transportation applications due to their relatively high efficiency and low pollutant emissions. Bipolar plates are the key components of these devices as they account for significant fractions of their weight and cost. Metallic materials have advantages over graphite-based ones because of their higher mechanical strength and better electrical conductivity. However, corrosion resistance is a major concern that remains to be solved as metals may develop oxide layers that increase electrical resistivity, thus lowering the fuel cell efficiency. This paper aims to present the main results found in recent literature about the corrosion performance of metallic bipolar plates. (author)

A study of novel regenerative braking system based on supercapacitor for electric vehicle driven by in-wheel motors

Directory of Open Access Journals (Sweden)

Li-qiang Jin

2015-03-01

Full Text Available Taking supercapacitor and battery pack as the energy storage unit, a novel type of regenerative braking system for electric vehicle driven by in-wheel motors is presented, and a braking energy regeneration control strategy is set up. Then, a co-simulation test based on CRUISE and Simulink is conducted. The results of simulation show that the novel type of system can ensure the safety of battery pack and significantly improve the rate of energy regeneration.

Regenerative medicine in dental and oral tissues: Dental pulp mesenchymal stem cell

Directory of Open Access Journals (Sweden)

Janti Sudiono

2017-08-01

Full Text Available Background. Regenerative medicine is a new therapeutic modality using cell, stem cell and tissue engineering technologies. Purpose. To describe the regenerative capacity of dental pulp mesenchymal stem cell. Review. In dentistry, stem cell and tissue engineering technologies develop incredibly and attract great interest, due to the capacity to facilitate innovation in dental material and regeneration of dental and oral tissues. Mesenchymal stem cells derived from dental pulp, periodontal ligament and dental follicle, can be isolated, cultured and differentiated into various cells, so that can be useful for regeneration of dental, nerves, periodontal and bone tissues. Tissue engineering is a technology in reconstructive biology, which utilizes mechanical, cellular, or biological mediators to facilitate regeneration or reconstruction of a particular tissue. The multipotency, high proliferation rates and accessibility, make dental pulp as an attractive source of mesenchymal stem cells for tissue regeneration. Revitalized dental pulp and continued root development is the focus of regenerative endodontic while biological techniques that can restore lost alveolar bone, periodontal ligament, and root cementum is the focus of regenerative periodontic. Conclucion. Dentin-derived morphogens such as BMP are known to be involved in the regulation of odontogenesis. The multipotency and angiogenic capacity of DPSCs as the regenerative capacity of human dentin / pulp complex indicated that dental pulp may contain progenitors that are responsible for dentin repair. The human periodontal ligament is a viable alternative source for possible primitive precursors to be used in stem cell therapy.

Nanotechnologies in regenerative medicine

Czech Academy of Sciences Publication Activity Database

Kubinová, Šárka; Syková, Eva

2010-01-01

Roč. 19, 3-4 (2010), s. 144-156 ISSN 1364-5706 R&D Projects: GA AV ČR IAA500390902; GA MŠk(CZ) LC554; GA AV ČR KAN201110651 Grant - others:GA ČR(CZ) 1M0538; GA ČR(CZ) GA203/09/1242; GA AV ČR(CZ) KAN200520804; EC FP6 project ENIMET(XE) LSHM-CT-2005-019063 Program:1M; GA; KA Institutional research plan: CEZ:AV0Z50390703 Keywords : Nanotechnology * regenerative medicine * nanofibers Subject RIV: FH - Neurology Impact factor: 1.051, year: 2010

Regenerative medicine in Europe: global competition and innovation governance.

Science.gov (United States)

Hogarth, Stuart; Salter, Brian

2010-11-01

Leading European nations with strong biotech sectors, such as the UK and Germany, are investing heavily in regenerative medicine, seeking competitive advantage in this emerging sector. However, in the broader biopharmaceutical sector, the EU is outperformed by the USA on all metrics, reflecting longstanding problems: limited venture capital finance, a fragmented patent system, and relatively weak relations between academia and industry. The current global downturn has exacerbated these difficulties. The crisis comes at a time when the EU is reframing its approach to the governance of innovation and renewing its commitment to the goal of making Europe the leading player in the global knowledge economy. If the EU is to gain a competitive advantage in the regenerative medicine sector then it must coordinate a complex multilevel governance framework that encompasses the EU, member states and regional authorities. This article takes stock of Europe's current competitive position within the global bioeconomy, drawing on a variety of metrics in the three intersecting spheres of innovation governance: science, market and society. These data then provide a platform for reviewing the problems of innovation governance faced by the EU and the strategic choices that have to be confronted in the regenerative medicine sector.

Regenerative endodontics: A state of the art

Directory of Open Access Journals (Sweden)

Rashmi Bansal

2011-01-01

Full Text Available Scientific advances in the creation of restorative biomaterials, in vitro cell culture technology, tissue grafting, tissue engineering, molecular biology and the human genome project provide the basis for the introduction of new technologies into dentistry. Non-vital infected teeth have long been treated with root canal therapy (for mature root apex and apexification (for immature root apex, or doomed to extraction. Although successful, current treatments fail to re-establish healthy pulp tissue in these teeth. But, what if the non-vital tooth could be made vital once again? That is the hope offered by regenerative endodontics, an emerging field focused on replacing traumatized and diseased pulp with functional pulp tissue. Restoration of vitality of non-vital tooth is based on tissue engineering and revascularization procedures. The purpose of this article is to review these biological procedures and the hurdles that must be overcome to develop regenerative endodontic procedures.

Turning Regenerative Medicine Breakthrough Ideas and Innovations into Commercial Products.

Science.gov (United States)

Bayon, Yves; Vertès, Alain A; Ronfard, Vincent; Culme-Seymour, Emily; Mason, Chris; Stroemer, Paul; Najimi, Mustapha; Sokal, Etienne; Wilson, Clayton; Barone, Joe; Aras, Rahul; Chiesi, Andrea

2015-12-01

The TERMIS-Europe (EU) Industry committee intended to address the two main critical issues in the clinical/commercial translation of Advanced Therapeutic Medicine Products (ATMP): (1) entrepreneurial exploitation of breakthrough ideas and innovations, and (2) regulatory market approval. Since January 2012, more than 12,000 publications related to regenerative medicine and tissue engineering have been accepted for publications, reflecting the intense academic research activity in this field. The TERMIS-EU 2014 Industry Symposium provided a reflection on the management of innovation and technological breakthroughs in biotechnology first proposed to contextualize the key development milestones and constraints of allocation of financial resources, in the development life-cycle of radical innovation projects. This was illustrated with the biofuels story, sharing similarities with regenerative medicine. The transition was then ensured by an overview of the key identified challenges facing the commercialization of cell therapy products as ATMP examples. Real cases and testimonies were then provided by a palette of medical technologies and regenerative medicine companies from their commercial development of cell and gene therapy products. Although the commercial development of ATMP is still at the proof-of-concept stage due to technology risks, changing policies, changing markets, and management changes, the sector is highly dynamic with a number of explored therapeutic approaches, developed by using a large diversity of business models, both proposed by the experience, pitfalls, and successes of regenerative medicine pioneers, and adapted to the constraint resource allocation and environment in radical innovation projects.

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.

Characterization of the emissions impacts of hybrid excavators with a portable emissions measurement system (PEMS)-based methodology.

Science.gov (United States)

Cao, Tanfeng; Russell, Robert L; Durbin, Thomas D; Cocker, David R; Burnette, Andrew; Calavita, Joseph; Maldonado, Hector; Johnson, Kent C

2018-04-13

Hybrid engine technology is a potentially important strategy for reduction of tailpipe greenhouse gas (GHG) emissions and other pollutants that is now being implemented for off-road construction equipment. The goal of this study was to evaluate the emissions and fuel consumption impacts of electric-hybrid excavators using a Portable Emissions Measurement System (PEMS)-based methodology. In this study, three hybrid and four conventional excavators were studied for both real world activity patterns and tailpipe emissions. Activity data was obtained using engine control module (ECM) and global positioning system (GPS) logged data, coupled with interviews, historical records, and video. This activity data was used to develop a test cycle with seven modes representing different types of excavator work. Emissions data were collected over this test cycle using a PEMS. The results indicated the HB215 hybrid excavator provided a significant reduction in tailpipe carbon dioxide (CO 2 ) emissions (from -13 to -26%), but increased diesel particulate matter (PM) (+26 to +27%) when compared to a similar model conventional excavator over the same duty cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

Transients of Water Distribution and Transport in PEM Fuel Cells

KAUST Repository

Hussaini, Irfan S.; Wang, Chao-Yang

2009-01-01

The response of polymer electrolyte membrane (PEM) fuel cells to a step change in load is investigated experimentally in this work. Voltage undershoot, a characteristic feature of transient response following a step increase in current, is due to transients of water distribution in the membrane and ionomers occurring at subsecond time scales. The use of humidified reactants as a means to control the magnitude of voltage undershoot is demonstrated. Further, the response under a step decrease in current density is explored to determine the existence of hysteresis. Under sufficiently humidified conditions, the responses under forward and reverse step changes are symmetric, but under low relative humidity conditions, voltage undershoot is twice as large as the overshoot. © 2009 The Electrochemical Society.

Experimental comparison of standard fuel cells PEM in radial configuration, coil and spiral; Comparacion experimental de celdas de combustible tipo PEM en configuracion radial, serpentin y espiral

Energy Technology Data Exchange (ETDEWEB)

Cano Andrade, Sergio

2008-12-15

After analyzing each one of the possible energy sources to replace oil the following question arises: which of all the possible sources is the suitable one? With no doubt another important factor in the election of this source is due to take into account, which has to do with the great problem that the humanity deals on a daily basis: the greenhouse effect. Taking into account the greenhouse effect, the fuel cells on the basis of hydrogen are the more viable energy source to substitute oil, since in their operation they are friendly with the environment since they do not produce polluting agents, reducing enormously the problem of global heating in which the planet is bottled. It is very certain that many disadvantages in these fuel cells on the basis of hydrogen still exist, but the arduous investigations realized until the present time foresee an excellent future where the planet will be able to satisfy its daily energy demand on the basis of the hydrogen technology. In future works one must have special care of the humidity control of gases before entering the fuel cell, since it is an important parameter in the correct operation of the standard fuel cells PEM. In the present investigation the advance in the state-of-the-art of the hydrogen technology is illustrated, specifically with the generation of electricity on the basis of the novel configurations of standard fuel cells PEM. Until the moment similar work it has not been found in the bibliography similar work where it is experienced with this type of radial configuration for the hydrogen technologies. The geometry and the results presented/displayed in this analysis correspond to a work of the highest category in the state-of-the-art of the fuel cells; in addition, an ample expectation due to the highly satisfactory results found, either numerically as well as experimentally, in comparison with other geometries is obtained. [Spanish] Despues de analizar cada una de las posibles fuentes de energia para

Stem Cells in Regenerative Medicine

OpenAIRE

Sykova, Eva; Forostyak, Serhiy

2013-01-01

Background: A number of cardiovascular, neurological, musculoskeletal and other diseases have a limited capacity for repair and only a modest progress has been made in treatment of brain diseases. The discovery of stem cells has opened new possibilities for the treatment of these maladies, and cell therapy now stands at the cutting-edge of modern regenerative medicine and tissue engineering. Experimental data and the first clinical trials employing stem cells have shown their broad therapeuti...

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...

Regenerative Snubber For GTO-Commutated SCR Inverter

Science.gov (United States)

Rippel, Wally E.; Edwards, Dean B.

1992-01-01

Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.

On friction braking demand with regenerative braking

NARCIS (Netherlands)

Walker, A.M.; Lampérth, M.U.; Wilkins, S.

2002-01-01

Developments in Hybrid Electric and pure Electric Vehicles are intended to improve the operational efficiency of road vehicles. Regenerative braking, which has long been established in rail vehicles, is integral to efficiency improvement, with up to 30% of overall traction energy demand satisfied by

A novel regenerative shock absorber with a speed doubling mechanism and its Monte Carlo simulation

Science.gov (United States)

Zhang, Ran; Wang, Xu; Liu, Zhenwei

2018-03-01

A novel regenerative shock absorber has been designed and fabricated. The novelty of the presented work is the application of the double speed regenerative shock absorber that utilizes the rack and pinion mechanism to increase the magnet speed with respect to the coils for higher power output. The simulation models with parameters identified from finite element analysis and the experiments are developed. The proposed regenerative shock absorber is compared with the regenerative shock absorber without the rack and pinion mechanism, when they are integrated into the same quarter vehicle suspension system. The sinusoidal wave road profile displacement excitation and the random road profile displacement excitation with peak amplitude of 0.035 m are applied as the inputs in the frequency range of 0-25 Hz. It is found that with the sinusoidal and random road profile displacement input, the proposed innovative design can increase the output power by 4 times comparing to the baseline design. The proposed double speed regenerative shock absorber also presents to be more sensitive to the road profile irregularity than the single speed regenerative shock absorber as suggested by Monte Carlo simulation. Lastly the coil mass and amplification factor are studied for sensitivity analysis and performance optimization, which provides a general design method of the regenerative shock absorbers. It shows that for the system power output, the proposed design becomes more sensitive to either the coil mass or amplification factor depending on the amount of the coil mass. With the specifically selected combination of the coil mass and amplification factor, the optimized energy harvesting performance can be achieved.

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)

Artificial organs versus regenerative medicine: is it true?

Science.gov (United States)

Nosé, Yukihiko; Okubo, Hisashi

2003-09-01

Individuals engaged in the fields of artificial kidney and artificial heart have often mistakenly stated that "the era of artificial organs is over; regenerative medicine is the future." Contrarily, we do not believe artificial organs and regenerative medicine are different medical technologies. As a matter of fact, artificial organs developed during the last 50 years have been used as a bridge to regeneration. The only difference between regenerative medicine and artificial organs is that artificial organs for the bridge to regeneration promote tissue regeneration in situ, instead of outside the body (for example, vascular prostheses, neuroprostheses, bladder substitutes, skin prostheses, bone prostheses, cartilage prostheses, ligament prostheses, etc.). All of these artificial organs are successful because tissue regeneration over a man-made prosthesis is established inside the patient's body (artificial organs to support regeneration). Another usage of the group of artificial organs for the bridge to regeneration is to sustain the functions of the patient's diseased organs during the regeneration process of the body's healthy tissues and/or organs. This particular group includes artificial kidney, hepatic assist, respiratory assist, and circulatory assist. Proof of regeneration of these healthy tissues and/or organs is demonstrated in the short-term recovery of end-stage organ failure patients (artificial organs for bridge to regeneration). A third group of artificial organs for the bridge to regeneration accelerates the regenerating process of the patient's healthy tissues and organs. This group includes neurostimulators, artificial blood (red cells) blood oxygenators, and plasmapheresis devices, including hemodiafiltrators. So-called "therapeutic artificial organs" fall into this category (artificial organs to accelerate regeneration). Thus, almost all of today's artificial organs are useful in the bridge to regeneration of healthy natural tissues and organs

Quo Vadis medycyno regeneracyjna?: Quo Vadis Regenerative Medicine?

Science.gov (United States)

Ratajczak, Mariusz Z; Suszyńska, Malwina

2013-07-01

There are presented the most important sources of pluripotent stem cells for potential application in the regenerative medicine. This review summarizes also advantages and disadvantages for potential application of these cells in clinical medicine.

Bipolar plates for PEM fuel cells

Science.gov (United States)

Middelman, E.; Kout, W.; Vogelaar, B.; Lenssen, J.; de Waal, E.

The bipolar plates are in weight and volume the major part of the PEM fuel cell stack, and are also a significant contributor to the stack costs. The bipolar plate is therefore a key component if power density has to increase and costs must come down. Three cell plate technologies are expected to reach targeted cost price levels, all having specific advantages and drawbacks. NedStack has developed a conductive composite materials and a production process for fuel cell plates (bipolar and mono-polar). The material has a high electric and thermal conductivity, and can be processed into bipolar plates by a proprietary molding process. Process cycle time has been reduced to less than 10 s, making the material and process suitable for economical mass production. Other development work to increase material efficiency resulted in thin bipolar plates with integrated cooling channels, and integrated seals, and in two-component bipolar plates. Total thickness of the bipolar plates is now less than 3 mm, and will be reduced to 2 mm in the near future. With these thin integrated plates it is possible to increase power density up to 2 kW/l and 2 kW/kg, while at the same time reducing cost by integrating other functions and less material use.

Different Approaches for Ensuring Performance/Reliability of Plastic Encapsulated Microcircuits (PEMs) in Space Applications

Science.gov (United States)

Gerke, R. David; Sandor, Mike; Agarwal, Shri; Moor, Andrew F.; Cooper, Kim A.

2000-01-01

Engineers within the commercial and aerospace industries are using trade-off and risk analysis to aid in reducing spacecraft system cost while increasing performance and maintaining high reliability. In many cases, Commercial Off-The-Shelf (COTS) components, which include Plastic Encapsulated Microcircuits (PEMs), are candidate packaging technologies for spacecrafts due to their lower cost, lower weight and enhanced functionality. Establishing and implementing a parts program that effectively and reliably makes use of these potentially less reliable, but state-of-the-art devices, has become a significant portion of the job for the parts engineer. Assembling a reliable high performance electronic system, which includes COTS components, requires that the end user assume a risk. To minimize the risk involved, companies have developed methodologies by which they use accelerated stress testing to assess the product and reduce the risk involved to the total system. Currently, there are no industry standard procedures for accomplishing this risk mitigation. This paper will present the approaches for reducing the risk of using PEMs devices in space flight systems as developed by two independent Laboratories. The JPL procedure involves primarily a tailored screening with accelerated stress philosophy while the APL procedure is primarily, a lot qualification procedure. Both Laboratories successfully have reduced the risk of using the particular devices for their respective systems and mission requirements.

Innovative regenerative medicines in the EU: a better future in evidence?

Science.gov (United States)

Corbett, Mark S; Webster, Andrew; Hawkins, Robert; Woolacott, Nerys

2017-03-08

Despite a steady stream of headlines suggesting they will transform the future of healthcare, high-tech regenerative medicines have, to date, been quite inaccessible to patients, with only eight having been granted an EU marketing licence in the last 7 years. Here, we outline some of the historical reasons for this paucity of licensed innovative regenerative medicines. We discuss the challenges to be overcome to expedite the development of this complex and rapidly changing area of medicine, together with possible reasons to be more optimistic for the future. Several factors have contributed to the scarcity of cutting-edge regenerative medicines in clinical practice. These include the great expense and difficulties involved in planning how individual therapies will be developed, manufactured to commercial levels and ultimately successfully delivered to patients. Specific challenges also exist when evaluating the safety, efficacy and cost-effectiveness of these therapies. Furthermore, many treatments are used without a licence from the European Medicines Agency, under "Hospital Exemption" from the EC legislation. For products which are licensed, alternative financing approaches by healthcare providers may be needed, since many therapies will have significant up-front costs but uncertain benefits and harms in the long-term. However, increasing political interest and more flexible mechanisms for licensing and financing of therapies are now evident; these could be key to the future growth and development of regenerative medicine in clinical practice. Recent developments in regulatory processes, coupled with increasing political interest, may offer some hope for improvements to the long and often difficult routes from laboratory to marketplace for leading-edge cell or tissue therapies. Collaboration between publicly-funded researchers and the pharmaceutical industry could be key to the future development of regenerative medicine in clinical practice; such collaborations

[Ethical aspects of regenerative medicine, with special reference to embryonic stem cells and therapeutic cloning].

Science.gov (United States)

Imura, Hiroo

2003-03-01

Regenerative medicine is expected to be new therapeutic means for treating incurable diseases but requires serious bioethical consideration. Embryonic stem(ES) cells, that are pleuripotent cells suitable to regenerative medicine, can be used in Japan for investigative use under a strict control by guide-lines. On the other hand, use of embryo produced by nuclear transfer has not been allowed in Japan and further serious consideration is required. Some other ethical aspects of regenerative medicine are also discussed.

Advanced Approaches to Greatly Reduce Hydrogen Gas Crossover Losses in PEM Electrolyzers Operating at High Pressures and Low Current Densities, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — ElectroChem proposes technology advances in its unique PEM IFF water electrolyzer design to meet the NASA requirement for an electrolyzer that will operate very...

REGENERATIVE DESIGN PRACTICES IN NIGERIA: A CASE ...

African Journals Online (AJOL)

User

2017-07-01

Jul 1, 2017 ... a view to effectively implement the concept within the study area. ... REGENERATIVE DESIGN PRACTICES IN NIGERIA: A CASE STUDY OF NGOZIKA HOUSING .... could mean greater acceptance of new development by the public and .... human/environment relations based on the Cartesian separation of ...

Ultrastructural study of the chromatoid body in planarian regenerative cells

Energy Technology Data Exchange (ETDEWEB)

Hori, I. (Kanazawa Medical Univ., Ishikawa (Japan))

1982-04-01

The present paper deals with the ultrastructural changes of chromatoid bodies in planarian regenerative cells under normal and experimental conditions. A close relationship was usually observed between chromatoid bodies and pore regions of the nuclear envelope in these cells. The chromatoid bodies continued to decrease in size during cytodifferentiation of regenerative cells, though they did not disappear entirely throughout the regeneration processes. Cytochemistry and (/sup 3/H)uridine autoradiography have shown that the chromatoid body contains RNA. The typical morphological effect of actinomycin D became apparent in three organelles, i.e., nucleolus, polysome and chromatoid body. Ultrastructural changes in nucleoli were observed to occur after actinomycin treatment (20 ..mu..g/ml). The exposure to a higher dose of actinomycin (50 ..mu..g/ml) caused a decay of chromatoid bodies while nuclear envelopes retained numerous pores. Both the nucleoli and the chromatoid bodies disappeared in the sequential stages. Within the cytoplasm of such cells disintegration of a polysomal pattern was correlated with the disappearance of chromatoid bodies. The significance of the planarian chromatoid body is discussed in relation to differentiation of the regenerative cells.

Error-rate performance analysis of opportunistic regenerative relaying

KAUST Repository

Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

2011-01-01

In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path can

Influences of bipolar plate channel blockages on PEM fuel cell performances

International Nuclear Information System (INIS)

Heidary, Hadi; Kermani, Mohammad J.; Dabir, Bahram

2016-01-01

Highlights: • Effect of partial- or full-blockage of PEMFC flow channels is numerically studied. • The anode blockage does not show any positive effects on cell performance. • Full blockages, despite higher pressure drop, better enhance net electrical power. • Additions of blocks more than five do not improve the cell performance. • Full blockage of cathode channels with five blocks enhances the net power by 30%. - Abstract: In this paper, the effect of partial- or full-block placement along the flow channels of PEM fuel cells is numerically studied. Blockage in the channel of flow-field diverts the flow into the gas diffusion layer (GDL) and enhances the mass transport from the channel core part to the catalyst layer, which in turn improves the cell performance. By partial blockage, only a part of the channel flow is shut off. While in full blockage, in which the flow channel cross sections are fully blocked, the only avenue left for the continuation of the gas is to travel over the blocks via the porous zone (GDL). In this study, a 3D numerical model consisting of a 9-layer PEM fuel cell is performed. A wide spectrum of numerical studies is performed to study the influences of the number of blocks, blocks height, and anode/cathode-side flow channel blockage. The results show that the case of full blockage enhances the net electrical power more than that of the partial blockage, in spite of higher pressure drop. Performed studies show that full blockage of the cathode-side flow channels with five blocks along the 5 cm channel enhances the net power by 30%. The present work provides helpful guidelines to bipolar plate manufacturers.

Modelling and analysis of a desiccant cooling system using the regenerative indirect evaporative cooling process

DEFF Research Database (Denmark)

Bellemo, Lorenzo; Elmegaard, Brian; Reinholdt, Lars O.

2013-01-01

This paper focuses on the numerical modeling and analysis of a Desiccant Cooling (DEC) system with regenerative indirect evaporative cooling, termed Desiccant Dewpoint Cooling (DDC) system. The DDC system includes a Desiccant Wheel (DW), Dew Point Coolers (DPCs), a heat recovery unit and a heat...... in different climates: temperate in Copenhagen and Mediterranean in Venice. Cheap and clean heat sources (e.g. solar energy) strongly increase the attractiveness of the DDC system. For the Mediterranean climate the DDC system represents a convenient alternative to chiller-based systems in terms of energy costs...... and CO2 emissions. The electricity consumption for auxiliaries in the DDC system is higher than in the chiller-based systems. The number of commercial-size DPC units required to cover the cooling load during the whole period is high: 8 in Copenhagen and 12 in Venice....

Modeling optimizes PEM fuel cell durability using three-dimensional multi-phase computational fluid dynamics model

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2010-01-01

Damage mechanisms in a proton exchange membrane (PEM) fuel cell are accelerated by mechanical stresses arising during fuel cell assembly (bolt assembling), and the stresses arise during fuel cell running, because it consists of the materials with different thermal expansion and swelling coefficients. Therefore, in order to acquire a complete understanding of the damage mechanisms in the membrane and gas diffusion layers, mechanical response under steady-state hygro-thermal stresses should be ...

Experimental Study and Comparison of Various Designs of Gas Flow Fields to PEM Fuel Cells and Cell Stack Performance

International Nuclear Information System (INIS)

Liu, Hong; Li, Peiwen; Juarez-Robles, Daniel; Wang, Kai; Hernandez-Guerrero, Abel

2014-01-01

In this study, a significant number of experimental tests to proton exchange membrane (PEM) fuel cells were conducted to investigate the effect of gas flow fields on fuel cell performance. Graphite plates with various flow field or flow channel designs, from literature survey and also novel designs by the authors, were used for the PEM fuel cell assembly. The fabricated fuel cells have an effective membrane area of 23.5 cm 2 . The results showed that the serpentine flow channel design is still favorable, giving the best single fuel cell performance amongst all the studied flow channel designs. A novel symmetric serpentine flow field was proposed for a relatively large sized fuel cell application. Four fuel cell stacks each including four cells were assembled using different designs of serpentine flow channels. The output power performances of fuel cell stacks were compared and the novel symmetric serpentine flow field design is recommended for its very good performance.

A micro-scale model for predicting contact resistance between bipolar plate and gas diffusion layer in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.; Lin, G.; Shih, A.J.; Hu, S.J. [Department of Mechanical Engineering, The University of Michigan, Ann Arbor, MI 48109-2125 (United States)

2007-01-01

Contact resistance between the bipolar plate (BPP) and the gas diffusion layer (GDL) in a proton exchange membrane (PEM) fuel cell constitutes a significant portion of the overall fuel cell electrical resistance under the normal operation conditions. Most current methods for contact resistance estimation are experimental and there is a lack of well developed theoretical methods. A micro-scale numerical model is developed to predict the electrical contact resistance between BPP and GDL by simulating the BPP surface topology and GDL structure and numerically determining the status for each contact spot. The total resistance and pressure are obtained by considering all contact spots as resistances in parallel and summing the results together. This model shows good agreements with experimental results. Influences of BPP surface roughness parameters on contact resistance are also studied. This model is beneficial in understanding the contact behavior between BPP and GDL and can be integrated with other fuel cell simulations to predict the overall performance of PEM fuel cells. (author)

Final Report - Advanced Cathode Catalysts and Supports for PEM Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Debe, Mark

2012-09-28

The principal objectives of the program were development of a durable, low cost, high performance cathode electrode (catalyst and support), that is fully integrated into a fuel cell membrane electrode assembly with gas diffusion media, fabricated by high volume capable processes, and is able to meet or exceed the 2015 DOE targets. Work completed in this contract was an extension of the developments under three preceding cooperative agreements/grants Nos. DE-FC-02-97EE50473, DE-FC-99EE50582 and DE-FC36- 02AL67621 which investigated catalyzed membrane electrode assemblies for PEM fuel cells based on a fundamentally new, nanostructured thin film catalyst and support system, and demonstrated the feasibility for high volume manufacturability.

Regenerative Payload for GSAT-3 & Advanced Communication ...

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Regenerative Payload for GSAT-3 & Advanced Communication Series Satellite. GSAT-4. 8 Ka -Band Spot Beams; 8 Narrow Band (64Kbps) Channels/ Beam; 1 Wide Band (2Mbps) Channel/ Beam;; 64 Kbps Signaling Channel; On-Board Switch Matrix; 8 Channel ...

Regenerative adsorbent heat pump

Science.gov (United States)

Jones, Jack A. (Inventor)

1991-01-01

A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Highly Efficient, Durable Regenerative Solid Oxide Stack, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes to develop a highly efficient regenerative solid oxide stack design. Novel structural elements allow direct internal...

Performance enhancement of a solar still using cotton regenerative medium

Directory of Open Access Journals (Sweden)

Thirumalai Gopal Sakthivel

2017-01-01

Full Text Available This paper presents the performance of a single slope solar still using cotton cloth regenerative medium. The performance was evaluated under the metrological conditions of Chennai city in India during the summer months of 2016. Two single-slope solar stills are fabricated with an effective area of 0.5 m2 with various thicknesses (2, 4, 6, and 8 mm of cotton cloth were used for the performance comparison. The results showed, the solar still with 6 mm thick cotton assisted regenerative solar still has about 28% improved productivity when compared to conventional solar still.

Two sides of the same coin: stem cells in cancer and regenerative medicine.

Science.gov (United States)

Ilmer, Matthias; Vykoukal, Jody; Recio Boiles, Alejandro; Coleman, Michael; Alt, Eckhard

2014-07-01

Multipotent stromal cells (MSCs) derived from bone marrow, adipose tissue, cord blood, and other origins have recently received much attention as potential therapeutic agents with beneficial immunomodulatory and regenerative properties. In their native tissue environment, however, such cells also appear to have essential functions in building and supporting tumor microenvironments, providing metastatic niches, and maintaining cancer hallmarks. Here, we consider the varied roles of these tissue-resident stroma-associated cells, synthesize recent and emerging discoveries, and discuss the role, potential, and clinical applications of MSCs in cancer and regenerative medicine.-Ilmer, M., Vykoukal, J., Recio Boiles, A., Coleman, M., Alt, E. Two sides of the same coin: stem cells in cancer and regenerative medicine. © FASEB.

Mechanism analysis and evaluation methodology of regenerative braking contribution to energy efficiency improvement of electrified vehicles

International Nuclear Information System (INIS)

Lv, Chen; Zhang, Junzhi; Li, Yutong; Yuan, Ye

2015-01-01

Highlights: • The energy flow of an electric vehicle with regenerative brake is analyzed. • Methodology for measuring the regen brake contribution is discussed. • Evaluation parameters of regen brake contribution are proposed. • Vehicle tests are carried out on chassis dynamometer. • Test results verify the evaluation method and parameters proposed. - Abstract: This article discusses the mechanism and evaluation methods of contribution brought by regenerative braking to electric vehicle’s energy efficiency improvement. The energy flow of an electric vehicle considering the braking energy regeneration was analyzed. Then, methodologies for measuring the contribution made by regenerative brake to vehicle energy efficiency improvement were introduced. Based on the energy flow analyzed, two different evaluation parameters were proposed. Vehicle tests were carried out on chassis dynamometer under typical driving cycles with three different control strategies. The experimental results the difference between the proposed two evaluation parameters, and demonstrated the feasibility and effectiveness of the evaluation methodologies proposed

Active Magnetic Regenerative Liquefier

Energy Technology Data Exchange (ETDEWEB)

Barclay, John A. [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Oseen-Send, Kathryn [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Ferguson, Luke [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Pouresfandiary, Jamshid [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Cousins, Anand [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Ralph, Heather [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States); Hampto, Tom [Heracles Energy Corporation d.b.a. Prometheus Energy, Washington, DC (United States)

2016-01-12

This final report for the DOE Project entitled Active Magnetic Regenerative Liquefier (AMRL) funded under Grant DE-FG36-08GO18064 to Heracles Energy Corporation d.b.a. Prometheus Energy (Heracles/Prometheus) describes an active magnetic regenerative refrigerator (AMRR) prototype designed and built during the period from July 2008 through May 2011. The primary goal of this project was to make significant technical advances toward highly efficient liquefaction of hydrogen. Conventional hydrogen liquefiers at any scale have a maximum FOM of ~0.35 due primarily to the intrinsic difficulty of rapid, efficient compression of either hydrogen or helium working gases. Numerical simulation modeling of high performance AMRL designs indicates certain designs have promise to increase thermodynamic efficiency from a FOM of ~0.35 toward ~0.5 to ~0.6. The technical approach was the use of solid magnetic working refrigerants cycled in and out of high magnetic fields to build an efficient active regenerative magnetic refrigeration module providing cooling power for AMRL. A single-stage reciprocating AMRR with a design temperature span from ~290 K to ~120 K was built and tested with dual magnetic regenerators moving in and out of the conductively-cooled superconducting magnet subsystem. The heat transfer fluid (helium) was coupled to the process stream (refrigeration/liquefaction load) via high performance heat exchangers. In order to maximize AMRR efficiency a helium bypass loop with adjustable flow was incorporated in the design because the thermal mass of magnetic refrigerants is higher in low magnetic field than in high magnetic field. Heracles/Prometheus designed experiments to measure AMRR performance under a variety of different operational parameters such as cycle frequency, magnetic field strength, heat transfer fluid flow rate, amount of bypass flow of the heat transfer fluid while measuring work input, temperature span, cooling capability as a function of cold temperature

Calculation of the hydrogen produced by a PEM electrolyzer based on solar radiation in Zacatecas; Estimacion del hidrogeno producido por un electrolizador PEM a partir de la radiacion solar en Zacatecas

Energy Technology Data Exchange (ETDEWEB)

Duron-Torres, S. M.; Villagrana-Munoz, L.E.; Garcia-Saldivar, V.M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico)]. E-mail: duronsm@prodigy.net.mx; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)

2009-09-15

This work presents the calculation of the amount of hydrogen obtained from the use of a proton exchange membrane electrolysis cell. Measurements performed at the solarimeter station of the Campus Siglo XXI at the Zacatecas Autonomous University were used as a basis. Solar radiation was analyzed for the period November 2007 to April 2008, corresponding to when there is less solar radiation. The amount of average irradiation measured was de 6.6 kW-h/ m{sup 2}. The evaluation of the solar-hydrogen system was conducted with linear regressions of the behavior of the hydrogen flow in LN/min versus the solar irradiance in W/m{sup 2} for a PEM electrolyzer. The results obtained indicate that the maximum amount of hydrogen produced occurred in the month of April, with 9LN/min produced with a radiation intensity of roughly 900 W/m{sup 2}; a minimum of 6 LN/min was produced with a radiation of roughly 600 W/m{sup 2} during the month of December. Based on these results, we can foresee a minimum amount of hydrogen generated of 6 to 9 LN/min in the state of Zacatecas during an entire year, since the months evaluated are those with the least solar radiation. The measurements performed by the Siglo XXI station show that the solar radiation power measured is higher than the national and worldwide means, making Zacatecas a strategic state for the use of this renewable energy. The amounts calculated of hydrogen produced would indicate that it is feasible to establish solar-hydrogen systems in this region in order to obtain this energy using PEM electrolyzers. [Spanish] En este trabajo se presenta el calculo de la cantidad de hidrogeno que se obtendria, empleando un electrolizador de membrana de intercambio de protones tipo, tomando como base las medidas realizadas en la Estacion Solarimetrica del Campus Siglo XXI en la Universidad Autonoma de Zacatecas. El analisis de la radiacion solar se realizo en el periodo de noviembre de 2007 a abril de 2008 correspondiendo a la epoca de menor

Flywheel and power unit

Energy Technology Data Exchange (ETDEWEB)

Seeley, R.W.

1992-10-28

A power unit, e.g. for an electrically driven vehicle, incorporates a flywheel for storing kinetic energy and a battery for storing electrical energy. The battery is incorporated as a substantial part of the rotating mass of the flywheel. Preferably the unit further includes an electrical machine being a motor or generator or machine operable either as a motor or a generator for transferring energy between the battery and the flywheel and/or for the input or output of rotary energy therefrom or thereto. The motor may be used for powering the flywheel and may also operate in a regenerative mode for recharging the unit on de-acceleration of the vehicle. The unit of the invention may also be utilized as an electrical stored power source, e.g. wind or water driven. (author)

Design, clinical translation and immunological response of biomaterials in regenerative medicine

Science.gov (United States)

Sadtler, Kaitlyn; Singh, Anirudha; Wolf, Matthew T.; Wang, Xiaokun; Pardoll, Drew M.; Elisseeff, Jennifer H.

2016-07-01

The field of regenerative medicine aims to replace tissues lost as a consequence of disease, trauma or congenital abnormalities. Biomaterials serve as scaffolds for regenerative medicine to deliver cells, provide biological signals and physical support, and mobilize endogenous cells to repair tissues. Sophisticated chemistries are used to synthesize materials that mimic and modulate native tissue microenvironments, to replace form and to elucidate structure-function relationships of cell-material interactions. The therapeutic relevance of these biomaterial properties can only be studied after clinical translation, whereby key parameters for efficacy can be defined and then used for future design. In this Review, we present the development and translation of biomaterials for two tissue engineering targets, cartilage and cornea, both of which lack the ability to self-repair. Finally, looking to the future, we discuss the role of the immune system in regeneration and the potential for biomaterial scaffolds to modulate immune signalling to create a pro-regenerative environment.

Development of a computer code for a regenerative Rankine cycle analysis

International Nuclear Information System (INIS)

Wi, Myung Hwan; Kim, Seong O; Choi, Seok Ki; Kim, Jin Hwan

2005-01-01

A regenerative Rankine cycle can increase the thermal efficiency of a steam system without increasing the steam pressure and temperature. The regenerative process involves heating the feedwater on its return trip to the steam generator by extracting steam at various stages of the turbine and transferring the energy to the feedwater via a feedwater heater. Some real plants use more than five feedwater heaters to enhance the cycle efficiency. However, the optimum number of feedwater heaters required is determined by balancing the efficiency improvement against the capital investment for a given cycle. In the present study, the computer code, TAOPCS, for the thermodynamic analysis of a regenerative steam cycle was developed to optimally design and accurately analyze the behavior of the power conversion system of Korea Advance Liquid Metal Reactor (KALIMER). In order to understand the functions and the characteristics of the code, the main features of the TAPCS were described and the example results are presented in this paper

Liver regenerative medicine: advances and challenges.

Science.gov (United States)

Chistiakov, Dimitry A

2012-01-01

Liver transplantation is the standard care for many end-stage liver diseases. However, donor organs are scarce and some people succumb to liver failure before a donor is found. Liver regenerative medicine is a special interdisciplinary field of medicine focused on the development of new therapies incorporating stem cells, gene therapy and engineered tissues in order to repair or replace the damaged organ. In this review we consider the emerging progress achieved in the hepatic regenerative medicine within the last decade. The review starts with the characterization of liver organogenesis, fetal and adult stem/progenitor cells. Then, applications of primary hepatocytes, embryonic and adult (mesenchymal, hematopoietic and induced pluripotent) stem cells in cell therapy of liver diseases are considered. Current advances and challenges in producing mature hepatocytes from stem/progenitor cells are discussed. A section about hepatic tissue engineering includes consideration of synthetic and natural biomaterials in engineering scaffolds, strategies and achievements in the development of 3D bioactive matrices and 3D hepatocyte cultures, liver microengineering, generating bioartificial liver and prospects for fabrication of the bioengineered liver. Copyright © 2012 S. Karger AG, Basel.

Scaffolds in regenerative endodontics: A review

Science.gov (United States)

Gathani, Kinjal M.; Raghavendra, Srinidhi Surya

2016-01-01

Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ‘A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ‘Platelet rich plasma’, ‘Platelet rich fibrin’, ‘Stem cells’, ‘Natural and artificial scaffolds’ from 1982–2015’. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon. PMID:27857762

Scaffolds in regenerative endodontics: A review

Directory of Open Access Journals (Sweden)

Kinjal M Gathani

2016-01-01

Full Text Available Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ′A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ′Platelet rich plasma′, ′Platelet rich fibrin′, ′Stem cells′, ′Natural and artificial scaffolds′ from 1982-2015′. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon.

Experimental investigation of dynamic performance and transient responses of a kW-class PEM fuel cell stack under various load changes

International Nuclear Information System (INIS)

Tang Yong; Yuan Wei; Pan Minqiang; Li Zongtao; Chen Guoqing; Li Yong

2010-01-01

The dynamic performance is a very important evaluation index of proton exchange membrane (PEM) fuel cells used for real application, which is mostly related with water, heat and gas management. A commercial PEM fuel cell system of Nexa module is employed to experimentally investigate the dynamic behavior and transient response of a PEM fuel cell stack and reveal involved influential factors. Five groups of dynamic tests are conducted and divided into different stage such as start-up, shut-down, step-up load, regular load variation and irregular load variation. It is observed that the external load changes the current output proportionally and reverses stack voltage accordingly. The purge operation benefits performance recovery and enhancement during a constant load and its time strongly depends on the operational current level. Overshoot and undershoot behaviors are observed during transience. But the current undershoot does not appear due to charge double-layer effect. Additionally, magnitudes of the peaks of the voltage overshoot and undershoot vary at different current levels. The operating temperature responds fast to current load but changes slowly showing an arc-like profile without any overshoot and undershoot events. The air flow rate changes directly following the dynamic load demand. But the increased amount of air flow rate during different step-change is not identical, which depends on the requirement of internal reaction and flooding intensity. The results can be utilized for validation of dynamic fuel cell models, and regarded as reference for effective control and management strategies.

Stem cells and regenerative medicine in domestic and companion animals: a multispecies perspective.

Science.gov (United States)

Gonçalves, N N; Ambrósio, C E; Piedrahita, J A

2014-10-01

Since their original isolation, the majority of the work on embryonic stem cells (ESC) has been carried out in mice. While the mouse is an outstanding model for basic research, it also has considerable limitations for translational work, especially in the area of regenerative medicine. This is due to a combination of factors that include physiological and size differences when compared to humans. In contrast, domestic animal species, such as swine, and companion animal species, such as dogs, provide unique opportunities to develop regenerative medicine protocols that can then be utilized in humans. Unfortunately, at present, the state of knowledge related to, and availability of, ESC from domestic animals vary among species such as pig, horse, dog and cat, and without exception lags significantly behind the mouse and human. It is clear that much still needs to be discovered. The 'stem cell-like' cell lines being reported are still not satisfactorily used in regenerative medicine, due to reasons such as heterogeneity and chromosomal instability. As a result, investigators have searched for alternate source of cells that can be used for regenerative medicine. This approach has uncovered a range of adult stem cells and adult progenitor cells that have utility in both human and veterinary medicine. Here, we review a range of stem cells, from ESC to induced pluripotent stem cells, and discuss their potential application in the field of regenerative medicine. © 2014 Blackwell Verlag GmbH.

Studies on PEM fuel cell noble metal catalyst dissolution

DEFF Research Database (Denmark)

Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.

2011-01-01

A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

Investigation of GDL compression effects on the performance of a PEM fuel cell cathode by lattice Boltzmann method

Science.gov (United States)

Molaeimanesh, G. R.; Nazemian, M.

2017-08-01

Proton exchange membrane (PEM) fuel cells with a great potential for application in vehicle propulsion systems will have a promising future. However, to overcome the exiting challenges against their wider commercialization further fundamental research is inevitable. The effects of gas diffusion layer (GDL) compression on the performance of a PEM fuel cell is not well-recognized; especially, via pore-scale simulation technique capturing the fibrous microstructure of the GDL. In the current investigation, a stochastic microstructure reconstruction method is proposed which can capture GDL microstructure changes by compression. Afterwards, lattice Boltzmann pore-scale simulation technique is adopted to simulate the reactive gas flow through 10 different cathode electrodes with dissimilar carbon paper GDLs produced from five different compression levels and two different carbon fiber diameters. The distributions of oxygen mole fraction, water vapor mole fraction and current density for the simulated cases are presented and analyzed. The results of simulations demonstrate that when the fiber diameter is 9 μm adding compression leads to lower average current density while when the fiber diameter is 7 μm the compression effect is not monotonic.

New model of inverting substation for DC traction with regenerative braking system

Science.gov (United States)

Omar, Abdul Malek Saidina; Samat, Ahmad Asri Abd; Isa, Siti Sarah Mat; Shamsuddin, Sarah Addyani; Jamaludin, Nur Fadhilah; Khyasudeen, Muhammad Farris

2017-08-01

This paper presents a power electronic devices application focus on modeling, analysis, and control of switching power converter in the inverting DC substation with regenerative braking system which is used to recycle the surplus regenerative power by feed it back to the main AC grid. The main objective of this research is to improve the switching power electronic converter of the railway inverting substation and optimize the maximum kinetic energy recovery together with minimum power losses from the railway braking system. Assess performance including efficiency and robustness will be evaluated in order to get the best solution for the design configuration. Research methodology included mathematical calculation, simulation, and detail analysis on modeling of switching power converter on inverting substation. The design stage separates to four main areas include rectification mode, regenerative mode, control inverter mode and filtering mode. The simulation result has shown that the regenerative inverter has a capability to accept a maximum recovery power on the regeneration mode. Total energy recovery has increase and power losses have decreases because inverter abilities to transfer the surplus energy back to the main AC supply. An Inverter controller with PWM Generator and PI Voltage Regulator has been designed to control voltage magnitude and frequency of the DC traction system.

Parameters Design for a Parallel Hybrid Electric Bus Using Regenerative Brake Model

Directory of Open Access Journals (Sweden)

Zilin Ma

2014-01-01

Full Text Available A design methodology which uses the regenerative brake model is introduced to determine the major system parameters of a parallel electric hybrid bus drive train. Hybrid system parameters mainly include the power rating of internal combustion engine (ICE, gear ratios of transmission, power rating, and maximal torque of motor, power, and capacity of battery. The regenerative model is built in the vehicle model to estimate the regenerative energy in the real road conditions. The design target is to ensure that the vehicle meets the specified vehicle performance, such as speed and acceleration, and at the same time, operates the ICE within an expected speed range. Several pairs of parameters are selected from the result analysis, and the fuel saving result in the road test shows that a 25% reduction is achieved in fuel consumption.

Regenerative dentistry: translating advancements in basic science research to the dental practice.

Science.gov (United States)

Garcia-Godoy, Franklin; Murray, Peter

2010-01-01

Scientific advances in the creation of restorative biomaterials, in vitro cell culture technology, tissue engineering, molecular biology and the human genome project provide the basis for the introduction of new technologies into dentistry. This review provides an assessment of how tissue engineering, stem cell, genetic transfer, biomaterial and growth factor therapies can be integrated into clinical dental therapies to restore and regenerate oral tissues. In parallel to the creation of a new field in general medicine called "regenerative medicine," we call this field "regenerative dentistry." While the problems of introducing regenerative therapies are substantial, the potential benefits to patients and the profession are equally ground-breaking. In this review, we outline a few areas of interest for the future of oral and dental medicine in which advancements in basic science have already been adapted to fit the goals of 21st century dentistry.

Hypoxia-based strategies for regenerative dentistry-Views from the different dental fields.

Science.gov (United States)

Müller, Anna Sonja; Janjić, Klara; Lilaj, Bledar; Edelmayer, Michael; Agis, Hermann

2017-09-01

The understanding of the cell biological processes underlying development and regeneration of oral tissues leads to novel regenerative approaches. Over the past years, knowledge on key roles of the hypoxia-based response has become more profound. Based on these findings, novel regenerative approaches for dentistry are emerging, which target cellular oxygen sensors. These approaches include hypoxia pre-conditioning and pharmacologically simulated hypoxia. The increase in studies on hypoxia and hypoxia-based strategies in regenerative dentistry highlights the growing attention to hypoxia's role in regeneration and its underlying biology, as well as its application in a therapeutic setting. In this narrative review, we present the current knowledge on the role of hypoxia in oral tissues and review the proposed hypoxia-based approaches in different fields of dentistry, including endodontics, orthodontics, periodontics, and oral surgery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vehicle emission factors of solid nanoparticles in the laboratory and on the road using Portable Emission Measurement Systems (PEMS

Directory of Open Access Journals (Sweden)

Barouch eGiechaskiel

2015-12-01

Full Text Available Emission inventories are used to quantify sources and identify trends in the emissions of air pollutants. They use vehicle-specific emission factors that are typically determined in the laboratory, through remote-sensing, vehicle chasing experiments and, more recently, on-board Portable Emission Measurement Systems (PEMS. Although PEMS is widely applied to measure gaseous pollutants, their application to Solid Particle Number (SPN emissions is new. In this paper, we discuss the current status of determining SPN emission factors both on the chassis dynamometer and on-road using PEMS-SPN. First, we determine the influence of the measurement equipment, ambient temperature, driving style and cycle characteristics, and the extra mass of the PEMS equipment on the SPN emissions. Afterward, we present the SPN emissions under type-approval conditions as well as on the road of two heavy-duty diesel vehicles equipped with Diesel Particulate Filter (DPF (one Euro VI, two light-duty diesel vehicles equipped with DPF, one light-duty vehicle equipped with a Port Fuel Injection engine (PFI, and seven Gasoline Direct Injection (GDI passenger cars (two Euro 6. We find that cold-start and strong accelerations tend to substantially increase SPN emissions. The two heavy-duty vehicles showed emissions around 2×10^13 p/km (Euro V truck and 6×10^10 p/km (Euro VI truck, respectively. One of the DPF-equipped light-duty vehicles showed emissions of 8×10^11 p/km, while the other one had one order of magnitude lower emissions. The PFI car had SPN emissions slightly higher than 1×10^12 p/km. The emissions of GDI cars spanned approximately from 8×10^11 p/km to 8×10^12 p/km. For the cars without DPF, the SPN emissions remained within a factor of two of the laboratory results. This factor was on average around 0.8 for the Euro 6 and 1.6 for the Euro 5 GDIs. The DPF equipped vehicles showed a difference of almost one order of magnitude between laboratory and on-road tests

Development of Regenerative Braking Co-operative Control System for Automatic Transmission-based Hybrid Electric Vehicle using Electronic Wedge Brake

OpenAIRE

Ko, Jiweon; Ko, Sungyeon; Bak, Yongsun; Jang, Mijeong; Yoo, Byoungsoo; Cheon, Jaeseung; Kim, Hyunsoo

2013-01-01

This research proposes a regenerative braking co-operative control system for the automatic transmission (AT)-based hybrid electric vehicle (HEV). The brake system of the subject HEV consists of the regenerative braking and the electronic wedge brake (EWB) friction braking for the front wheel, and the hydraulic friction braking for the rear wheel. A regenerative braking co-operative control algorithm is suggested for the regenerative braking and friction braking, which distributes the braking...

Experimental study of a PEM 15 W fuel cell; Influencia das temperaturas de operacao e umidificacao no desempenho de uma celula combustivel tipo 'PEM' de 15 W

Energy Technology Data Exchange (ETDEWEB)

Heusi, Daniel S.; Steidel, Paulo S.; Matelli, Jose A. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Lab. de Combustao e Engenharia de Sistemas Termicos (LabCET); Bazzo, Edson [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2004-07-01

Experimental results are presented for a fuel cell type PEM of 15 W. The influence of the operating temperature, as well as the effect of the humidification temperature in the draining of the gases Hydrogen and oxygen, are considered for analysis. The tests were performed at operating temperature in the range of 30 to 70 deg C and humidification temperature form 30 to 85 deg C. For hydrogen flows fixed to be 200 ml/min and 300 ml/min, as well as for oxygen flow of 165 ml/min, the polarization curves were raised taking into account different combinations of operation and different combinations of humidification temperatures. (author)

The current 'state of play' of regenerative medicine in horses: what the horse can tell the human.

Science.gov (United States)

Smith, Roger Kw; Garvican, Elaine R; Fortier, Lisa A

2014-01-01

The horse is an attractive model for many human age-related degenerative diseases of the musculoskeletal system because it is a large animal species that both ages and exercises, and develops naturally occurring injuries with many similarities to the human counterpart. It therefore represents an ideal species to use as a 'proving ground' for new therapies, most notably regenerative medicine. Regenerative techniques using cell-based therapies for the treatment of equine musculoskeletal disease have been in use for over a decade. This review article provides a summary overview of the sources, current challenges and problems surrounding the use of stem cell and non-cell-based therapy in regenerative medicine in horses and is based on presentations from a recent Havemeyer symposium on equine regenerative medicine where speakers are selected from leading authorities in both equine and human regenerative medicine fields from 10 different countries.

Advanced Space Power Systems (ASPS): Regenerative Fuel Cells (RFC)

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the regenerative fuel cell project element is to develop power and energy storage technologies that enable new capabilities for future human space...

Translating Regenerative Biomaterials Into Clinical Practice.

Science.gov (United States)

Stace, Edward T; Dakin, Stephanie G; Mouthuy, Pierre-Alexis; Carr, Andrew J

2016-01-01

Globally health care spending is increasing unsustainably. This is especially true of the treatment of musculoskeletal (MSK) disease where in the United States the MSK disease burden has doubled over the last 15 years. With an aging and increasingly obese population, the surge in MSK related spending is only set to worsen. Despite increased funding, research and attention to this pressing health need, little progress has been made toward novel therapies. Tissue engineering and regenerative medicine (TERM) strategies could provide the solutions required to mitigate this mounting burden. Biomaterial-based treatments in particular present a promising field of potentially cost-effective therapies. However, the translation of a scientific development to a successful treatment is fraught with difficulties. These barriers have so far limited translation of TERM science into clinical treatments. It is crucial for primary researchers to be aware of the barriers currently restricting the progression of science to treatments. Researchers need to act prospectively to ensure the clinical, financial, and regulatory hurdles which seem so far removed from laboratory science do not stall or prevent the subsequent translation of their idea into a treatment. The aim of this review is to explore the development and translation of new treatments. Increasing the understanding of these complexities and barriers among primary researchers could enhance the efficiency of biomaterial translation. © 2015 Wiley Periodicals, Inc.

A Study on Control Strategy of Regenerative Braking in the Hydraulic Hybrid Vehicle Based on ECE Regulations

Directory of Open Access Journals (Sweden)

Tao Liu

2013-01-01

Full Text Available This paper establishes a mathematic model of composite braking in the hydraulic hybrid vehicle and analyzes the constraint condition of parallel regenerative braking control algorithm. Based on regenerative braking system character and ECE (Economic Commission of Europe regulations, it introduces the control strategy of regenerative braking in parallel hydraulic hybrid vehicle (PHHV. Finally, the paper establishes the backward simulation model of the hydraulic hybrid vehicle in Matlab/simulink and makes a simulation analysis of the control strategy of regenerative braking. The results show that this strategy can equip the hydraulic hybrid vehicle with strong brake energy recovery power in typical urban drive state.

Free radical scavenging injectable hydrogels for regenerative therapy

Energy Technology Data Exchange (ETDEWEB)

Komeri, Remya [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India); Thankam, Finosh Gnanaprakasam [Dept. of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha NE68178 (United States); Muthu, Jayabalan, E-mail: mjayabalan52@gmail.com [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India)

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Free radical scavenging injectable hydrogels for regenerative therapy

International Nuclear Information System (INIS)

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-01-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Flow channel shape optimum design for hydroformed metal bipolar plate in PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Peng, Linfa; Lai, Xinmin; Liu, Dong' an; Hu, Peng [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240 (China); Ni, Jun [Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI 48109 (United States)

2008-03-15

Bipolar plate is one of the most important and costliest components of polymer electrolyte membrane (PEM) fuel cells. Micro-hydroforming is a promising process to reduce the manufacturing cost of PEM fuel cell bipolar plates made of metal sheets. As for hydroformed bipolar plates, the main defect is the rupture because of the thinning of metal sheet during the forming process. The flow channel section decides whether high quality hydroformed bipolar plates can be successively achieved or not. Meanwhile, it is also the key factor that is related with the reaction efficiency of the fuel cell stacks. In order to obtain the optimum flow channel section design prior the experimental campaign, some key geometric dimensions (channel depth, channel width, rib width and transition radius) of flow channel section, which are related with both reaction efficiency and formability, are extracted and parameterized as the design variables. By design of experiments (DOE) methods and an adoptive simulated annealing (ASA) optimization method, an optimization model of flow channel section design for hydroformed metal bipolar plate is proposed. Optimization results show that the optimum dimension values for channel depth, channel width, rib width and transition radius are 0.5, 1.0, 1. 6 and 0.5 mm, respectively with the highest reaction efficiency (79%) and the acceptable formability (1.0). Consequently, their use would lead to improved fuel cell efficiency for low cost hydroformed metal bipolar plates. (author)

VOF modelling of gas–liquid flow in PEM water electrolysis cell micro-channels

DEFF Research Database (Denmark)

Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

2017-01-01

In this study, the gaseliquid flow through an interdigitated anode flow field of a PEM water electrolysis cell (PEMEC) is analysed using a three-dimensional, transient, computational fluid dynamics (CFD) model. To account for two-phase flow, the volume of fluid (VOF) method in ANSYS Fluent 17...... of the channel. The model is capable of revealing effect of different bubble shapes/lengths in the outgoing channel. Shape and the sequence of the bubbles affect the water flow distribution in the ATL. The model presented in this work is the first step in the development of a comprehensive CFD model...

A regenerative biology view on artificial tissue construction and 3D bioprinting: what may we learn from natural regenerative phenomena?

DEFF Research Database (Denmark)

Lauridsen, Henrik

2017-01-01

The implications of the low tissue regenerative potential in humans are severe and widespread. Several of our major diseases are direct results of this deficiency that leaves us vulnerable to events of tissue damage. This is opposed to some animal groups, such as the urodele amphibians (salamanders...

Educational tool for modeling and simulation of a closed regenerative life support system

Science.gov (United States)

Arai, Tatsuya; Fanchiang, Christine; Aoki, Hirofumi; Newman, Dava J.

For long term missions on the moon and Mars, regenerative life support systems emerge as a promising key technology for sustaining successful explorations with reduced re-supply logistics and cost. The purpose of this study was to create a simple model of a regenerative life support system which allows preliminary investigation of system responses. A simplified regenerative life support system was made with MATLAB Simulink ™. Mass flows in the system were simplified to carbon, water, oxygen and carbon dioxide. The subsystems included crew members, animals, a plant module, and a waste processor, which exchanged mass into and out of mass reservoirs. Preliminary numerical simulations were carried out to observe system responses. The simplified life support system model allowed preliminary investigation of the system response to perturbations such as increased or decreased number of crew members. The model is simple and flexible enough to add new components, and also possible to numerically predict non-linear subsystem functions and responses. Future work includes practical issues such as energy efficiency, air leakage, nutrition, and plant growth modeling. The model functions as an effective teaching tool about how a regenerative advanced life support system works.

Energy recapture through deceleration - regenerative braking in electric vehicles from a user perspective.

Science.gov (United States)

Cocron, Peter; Bühler, Franziska; Franke, Thomas; Neumann, Isabel; Dielmann, Benno; Krems, Josef F

2013-01-01

We report results from a 1-year field study (N = 80) on user interactions with regenerative braking in electric vehicles. Designed to recapture energy in vehicles with electric powertrains, regenerative braking has an important influence on both the task of driving and energy consumption. Results from user assessments and data from onboard data loggers indicate that most drivers quickly learned to interact with the system, which was triggered via accelerator. Further, conventional braking manoeuvres decreased significantly as the majority of deceleration episodes could only be executed through regenerative braking. Still, some drivers reported difficulties when adapting to the system. These difficulties could be addressed by offering different levels of regeneration so that the intensity of the deceleration could be individually modified. In general, the system is trusted and regarded as a valuable tool for prolonging range. Regenerative braking in electric vehicles has direct implications for the driving task. We found that drivers quickly learn to use and accept a system, which is triggered via accelerator. For those reporting difficulties in the interaction, it appears reasonable to integrate options to customise or switch off the system.

Electrolyzer for NASA Lunar Regenerative Fuel Cells, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Water electrolyzer stacks are a key component of regenerative fuel cells, designed to replace batteries as a means of storing electric energy on the lunar surface....

Regenerative medicine: A ray of light for medical science

Directory of Open Access Journals (Sweden)

Swapna Supekar

2016-01-01

Full Text Available The perimeters of medical science have expanded to include regenerative medicine as a translational science, which has the potential to revolutionize the treatment of incapacitating diseases and chronic disorders.

Regenerative adsorption distillation system

KAUST Repository

Ng, Kim Choon; Thu, Kyaw; Amy, Gary; Chunggaze, Mohammed; Al-Ghasham, Tawfiq

2013-01-01

There is provided a regenerative adsorption distillation system comprising a train of distillation effects in fluid communication with each other. The train of distillation effects comprises at least one intermediate effect between the first and last distillation effects of the train, each effect comprising a vessel and a condensing tube for flow of a fluid therein. The system further comprises a pair of adsorption-desorption beds in vapour communication with the last effect and at least one intermediate effect, wherein the beds contain an adsorbent that adsorbs vapour from the last effect and transmits desorbed vapour into at least one of the intermediate effect.

Regenerative adsorption distillation system

KAUST Repository

Ng, Kim Choon

2013-12-26

There is provided a regenerative adsorption distillation system comprising a train of distillation effects in fluid communication with each other. The train of distillation effects comprises at least one intermediate effect between the first and last distillation effects of the train, each effect comprising a vessel and a condensing tube for flow of a fluid therein. The system further comprises a pair of adsorption-desorption beds in vapour communication with the last effect and at least one intermediate effect, wherein the beds contain an adsorbent that adsorbs vapour from the last effect and transmits desorbed vapour into at least one of the intermediate effect.

REAC regenerative treatment efficacy in experimental chondral lesions: a pilot study on ovine animal model

Directory of Open Access Journals (Sweden)

Sanna Passino E

2017-09-01

Full Text Available Eraldo Sanna Passino,1,2 Stefano Rocca,1 Sabrina Caggiu,1 Nicolò Columbano,1,2 Alessandro Castagna,3 Vania Fontani,3–5 Salvatore Rinaldi3–51Department of Veterinary Medicine, University of Sassari, Sassari, Italy; 2Comparative Surgery Research Laboratory, University of Sassari, Sassari, Italy; 3Department of Regenerative Medicine, Rinaldi Fontani Institute, Florence, Italy; 4Research Department, Rinaldi Fontani Foundation, Florence, Italy; 5Research Department, IRF Shanghai Biomedical Sciences, Shanghai, People’s Republic of China Abstract: Radioelectric asymmetric conveyor (REAC technology is a platform designed to optimize cell polarity. Cell polarity is a universal biological phenomenon that is implicated in cell differentiation, proliferation, morphogenesis, aging, and rejuvenation. In this work, we investigate a timing and administration protocol for tissue optimization regenerative treatment type C, in order to treat aging-related chondral damage or injuries and gain insights into regenerative processes of articular cartilage in humans. The chondral lesion produced in this study in an animal model (6 knee joints of 4 adult sheep was 6 mm in diameter and about 2 mm deep. These lesions, which did not involve subchondral bone, tend to increase in size and depth and are not completely repaired with normal hyaline articular cartilage since adult articular cartilage is avascular and has a very slow turnover at the cellular and molecular level. Moreover, the hydration of articular cartilage is reduced with aging and with decreased mitotic activity, synthesis, and population size of chondrocytes. Six months posttreatment, lesions appeared filled, though not completely, with newly generated tissue of the light opalescent color of healthy articular cartilage, which otherwise covered the underlying subchondral bone. The newly formed tissue surface appeared to be quite regular. Nearly complete regeneration of subchondral bone occurred, with

Engineering growth factors for regenerative medicine applications.

Energy Technology Data Exchange (ETDEWEB)

Mitchell, Aaron C.; Briquez, Priscilla S.; Hubbell, Jeffrey A.; Cochran, Jennifer R.

2016-01-15

Growth factors are important morphogenetic proteins that instruct cell behavior and guide tissue repair and renewal. Although their therapeutic potential holds great promise in regenerative medicine applications, translation of growth factors into clinical treatments has been hindered by limitations including poor protein stability, low recombinant expression yield, and suboptimal efficacy. This review highlights current tools, technologies, and approaches to design integrated and effective growth factor-based therapies for regenerative medicine applications. The first section describes rational and combinatorial protein engineering approaches that have been utilized to improve growth factor stability, expression yield, biodistribution, and serum half-life, or alter their cell trafficking behavior or receptor binding affinity. The second section highlights elegant biomaterial-based systems, inspired by the natural extracellular matrix milieu, that have been developed for effective spatial and temporal delivery of growth factors to cell surface receptors. Although appearing distinct, these two approaches are highly complementary and involve principles of molecular design and engineering to be considered in parallel when developing optimal materials for clinical applications.

PRMT7 Preserves Satellite Cell Regenerative Capacity

Directory of Open Access Journals (Sweden)

Roméo Sébastien Blanc

2016-02-01

Full Text Available Regeneration of skeletal muscle requires the continued presence of quiescent muscle stem cells (satellite cells, which become activated in response to injury. Here, we report that whole-body protein arginine methyltransferase PRMT7−/− adult mice and mice conditionally lacking PRMT7 in satellite cells using Pax7-CreERT2 both display a significant reduction in satellite cell function, leading to defects in regenerative capacity upon muscle injury. We show that PRMT7 is preferentially expressed in activated satellite cells and, interestingly, PRMT7-deficient satellite cells undergo cell-cycle arrest and premature cellular senescence. These defects underlie poor satellite cell stem cell capacity to regenerate muscle and self-renew after injury. PRMT7-deficient satellite cells express elevated levels of the CDK inhibitor p21CIP1 and low levels of its repressor, DNMT3b. Restoration of DNMT3b in PRMT7-deficient cells rescues PRMT7-mediated senescence. Our findings define PRMT7 as a regulator of the DNMT3b/p21 axis required to maintain muscle stem cell regenerative capacity.

Multiple excitation regenerative amplifier inertial confinement system

International Nuclear Information System (INIS)

George, V.E.; Haas, R.A.; Krupke, W.F.; Schlitt, L.G.

1980-01-01

The invention relates to apparatus and methods for producing high intensity laser radiation generation which is achieved through an optical amplifier-storage ring design. One or two synchronized, counterpropagating laser pulses are injected into a regenerative amplifier cavity and amplified by gain media which are pumped repetitively by electrical or optical means. The gain media excitation pulses are tailored to efficiently amplify the laser pulses during each transit. After the laser pulses have been amplified to the desired intensity level, they are either switched out of the cavity by some switch means, as for example an electro-optical device, for any well known laser end uses, or a target means may be injected into the regenerative amplifier cavity in such a way as to intercept simultaneously the counterpropagating laser pulses. One such well known end uses to which this invention is intended is for production of high density and temperature plasmas suitable for generating neutrons, ions and x-rays and for studying matter heated by high intensity laser radiation

Enhanced Regenerative Braking Strategies for Electric Vehicles: Dynamic Performance and Potential Analysis

OpenAIRE

Boyi Xiao; Huazhong Lu; Hailin Wang; Jiageng Ruan; Nong Zhang

2017-01-01

A regenerative braking system and hydraulic braking system are used in conjunction in the majority of electric vehicles worldwide. We propose a new regenerative braking distribution strategy that is based on multi-input fuzzy control logic while considering the influences of the battery’s state of charge, the brake strength and the motor speed. To verify the braking performance and recovery economy, this strategy was applied to a battery electric vehicle model and compared with two other impr...

MSCs-derived exosomes: cell-secreted nanovesicles with regenerative potential

Directory of Open Access Journals (Sweden)

Ana Marote

2016-08-01

Full Text Available Exosomes are membrane-enclosed nanovesicles (30-150 nm that shuttle active cargoes between different cells. These tiny extracellular vesicles have been recently isolated from mesenchymal stem cells (MSCs conditioned medium, a population of multipotent cells identified in several adult tissues. MSCs paracrine activity has been already shown to be the key mediator of their elicited regenerative effects. On the other hand, the individual contribution of MSCs-derived exosomes for these effects is only now being unraveled. The administration of MSCs-derived exosomes has been demonstrated to restore tissue function in multiple diseases/injury models and to induce beneficial in vitro effects, mainly mediated by exosomal-enclosed miRNAs. Additionally, the source and the culture conditions of MSCs have been shown to influence the regenerative responses induced by exosomes. Therefore, these studies reveal that MSCs-derived exosomes hold a great potential for cell-free therapies that are safer and easier to manipulate than cell-based products. Nevertheless, this is an emerging research field and hence, further studies are required to understand the full dimension of this complex intercellular communication system and how it can be optimized to take full advantage of its therapeutic effects. In this mini-review, we summarize the most significant new advances in the regenerative properties of MSCs-derived exosomes and discuss the molecular mechanisms underlying these effects.

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

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2013-01-01

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

A Study on Control Strategy of Regenerative Braking in the Hydraulic Hybrid Vehicle Based on ECE Regulations

OpenAIRE

Liu, Tao; Zheng, Jincheng; Su, Yongmao; Zhao, Jinghui

2013-01-01

This paper establishes a mathematic model of composite braking in the hydraulic hybrid vehicle and analyzes the constraint condition of parallel regenerative braking control algorithm. Based on regenerative braking system character and ECE (Economic Commission of Europe) regulations, it introduces the control strategy of regenerative braking in parallel hydraulic hybrid vehicle (PHHV). Finally, the paper establishes the backward simulation model of the hydraulic hybrid vehicle in Matlab/simul...

An ultrastructural study of the chromatoid body in planarian regenerative cells

International Nuclear Information System (INIS)

Hori, Isao

1982-01-01

The present paper deals with the ultrastructural changes of chromatoid bodies in planarian regenerative cells under normal and experimental conditions. A close relationship was usually observed between chromatoid bodies and pore regions of the nuclear envelope in these cells. The chromatoid bodies continued to decrease in size during cytodifferentiation of regenerative cells, though they did not disappear entirely throughout the regeneration processes. Cytochemistry and [ 3 H]uridine autoradiography have shown that the chromatoid body contains RNA. The typical morphological effect of actinomycin D became apparent in three organelles, i.e., nucleolus, polysome and chromatoid body. Ultrastructural changes in nucleoli were observed to occur after actinomycin treatment (20 μg/ml). The exposure to a higher dose of actinomycin (50 μg/ml) caused a decay of chromatoid bodies while nuclear envelopes retained numerous pores. Both the nucleoli and the chromatoid bodies disappeared in the sequential stages. Within the cytoplasm of such cells disintegration of a polysomal pattern was correlated with the disappearance of chromatoid bodies. The significance of the planarian chromatoid body is discussed in relation to differentiation of the regenerative cells. (author)

Downward Slope Driving Control for Electric Powered Wheelchair Based on Capacitor Regenerative Brake

Science.gov (United States)

Seki, Hirokazu; Takahashi, Yoshiaki

This paper describes a novel capacitor regenerative braking control scheme of electric powered wheelchairs for efficient driving on downward slopes. An electric powered wheelchair, which generates the driving force by electric motors, is expected to be widely used as a mobility support system for elderly people and disabled people; however the energy efficiency has to be further improved because it is driven only by battery energy. This study proposes a capacitor regenerative braking circuit and two types of velocity control schemes with variable duty ratio. The proposed regenerative braking circuit is based on the step-up/down circuit with additional resistance and connects right and left motors in series in order to obtain a larger braking power. Some driving experiments on a practical downward slope show the effectiveness of the proposed control system.

Development and test of 2 kW natural gas reformers for high and low temperature PEM fuel cells. Project report 2; Udvikling/afproevning af 2 kW naturgasreformere for hoej- og lavtemperatur PEM-braendselsceller. Projektrapport 2

Energy Technology Data Exchange (ETDEWEB)

Wit, J. de [Dansk Gasteknisk Center (Denmark); Bech-Madsen, J. [IRD (Denmark); Bandur, V. [DTU (Denmark); Bartholin, N. [DPS (Denmark)

2005-11-15

The use of fuel cells for combined heat and power generation has advantages as regards technology and usability compared to existing CHP technology. Special characteristics for a fuel cell plant are: 1) It can be constructed in modules over a wide power range, 2) The efficiency is significantly independent of size, 3) It is noiseless, 4) A flexible coupling between power and heat production, 5) As there is no movable parts, long service check intervals can be expected, 6) Low emissions. The fuel for fuel cells is hydrogen and optimal utilization and CO{sub 2} reduction will require a 'hydrogen society'. While waiting for a 'hydrogen society' to arise, it is possible to use central or on-site reformers that convert natural gas to hydrogen. There will be some CO{sub 2} emission connected to energy use. The objective of the present project has been development and test of on-site reformers (fuel processors) for hydrogen supply to respectively high and low temperature PEM fuel cells aiming at use in single family houses. Sulphur cleaning, reformers, and lab-scale coupling with fuel cell KV units have been developed and tested during the project, as well as development and test of periphery equipment. (BA)

Regenerative Heater Optimization for Steam Turbo-Generation Cycles of Generation IV Nuclear Power Plants with a Comparison of Two Concepts for the Westinghouse International Reactor Innovative and Secure (IRIS)

International Nuclear Information System (INIS)

Williams, W.C.

2002-01-01

The intent of this study is to discuss some of the many factors involved in the development of the design and layout of a steam turbo-generation unit as part of a modular Generation IV nuclear power plant. Of the many factors involved in the design and layout, this research will cover feed water system layout and optimization issues. The research is arranged in hopes that it can be generalized to any Generation IV system which uses a steam powered turbo-generation unit. The research is done using the ORCENT-II heat balance codes and the Salisbury methodology to be reviewed herein. The Salisbury methodology is used on an original cycle design by Famiani for the Westinghouse IRIS and the effects due to parameter variation are studied. The vital parameters of the Salisbury methodology are the incremental heater surface capital cost (S) in $/ft 2 , the value of incremental power (I) in $/kW, and the overall heat transfer coefficient (U) in Btu/ft 2 -degrees Fahrenheit-hr. Each is varied in order to determine the effects on the cycles overall heat rate, output, as well as, the heater surface areas. The effects of each are shown. Then the methodology is then used to compare the optimized original Famiani design consisting of seven regenerative feedwater heaters with an optimized new cycle concept, INRC8, containing four regenerative heaters. The results are shown. It can be seen that a trade between the complexity of the seven stage regenerative Famiani cycle and the simplicity of the INRC8 cycle can be made. It is desired that this methodology can be used to show the ability to evaluate modularity through the value of size a complexity of the system as well as the performance. It also shows the effectiveness of the Salisbury methodology in the optimization of regenerative cycles for such an evaluation

New results on performance analysis of opportunistic regenerative relaying

KAUST Repository

Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2013-01-01

In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may

Adaptive Regenerative Braking in Electric Vehicles

OpenAIRE

Kubaisi, Rayad

2018-01-01

Elektrofahrzeuge fahren lokal emissionsfrei und tragen damit dazu bei, die Emissionen in Städten zu reduzieren. Zusätzlich, zeichnen sich Elektrofahrzeuge durch ein dynamisches Fahrverhalten aus. Nachteilig wirkt sich bei den meisten Elektrofahrzeugen, die geringe Reichweite auf die Akzeptanz bei Neuwagenkäufern aus. Eine der Maßnahmen zur Erhöhung der Reichweite von Elektrofahrzeuge ist das regenerative Bremsen. Hierbei wird die kinetische Energie des Fahrzeugs durch generatorisches...

MicroRNAs in Tissue Engineering and Regenerative Medicine

NARCIS (Netherlands)

Krenning, Guido; Harmsen, Martin; Sen, Chandan

2015-01-01

The body has a large regenerative capacity to cope with the continuous adverse challenges of high-calorie diets, aging, inflammation, and wear and tear, as well as acute injuries such as myocardial infarction. However, if the amount of sustained damage exceeds the body’s repair capacity,

A three-dimensional model of PEM fuel cells with serpentine flow channels

International Nuclear Information System (INIS)

Nguyen, P.T.; Berning, T.; Bang, M.; Djilali, N.

2003-01-01

A three-dimensional computational model of PEM fuel cell with serpentine flow field channels is presented in this paper. This model presents a comprehensive account for all important transport phenomena in fuel cell such as heat transfer, mass transfer, electrode kinetics, and potential fields in the membrane and gas diffusion layers. A new approach of solving for the potential losses across the cell was also developed in this model. The dependency of local current density on oxygen concentration and activation overpotential is fully addressed in this model. The computational domain consists of serpentine gas flow channels, porous gas diffusion layers, catalyst layers, and a membrane. Results obtained from this model are in good agreement with experimental results. (author)

Human dental pulp stem cells: Applications in future regenerative medicine

Science.gov (United States)

Potdar, Pravin D; Jethmalani, Yogita D

2015-01-01

Stem cells are pluripotent cells, having a property of differentiating into various types of cells of human body. Several studies have developed mesenchymal stem cells (MSCs) from various human tissues, peripheral blood and body fluids. These cells are then characterized by cellular and molecular markers to understand their specific phenotypes. Dental pulp stem cells (DPSCs) are having a MSCs phenotype and they are differentiated into neuron, cardiomyocytes, chondrocytes, osteoblasts, liver cells and β cells of islet of pancreas. Thus, DPSCs have shown great potentiality to use in regenerative medicine for treatment of various human diseases including dental related problems. These cells can also be developed into induced pluripotent stem cells by incorporation of pluripotency markers and use for regenerative therapies of various diseases. The DPSCs are derived from various dental tissues such as human exfoliated deciduous teeth, apical papilla, periodontal ligament and dental follicle tissue. This review will overview the information about isolation, cellular and molecular characterization and differentiation of DPSCs into various types of human cells and thus these cells have important applications in regenerative therapies for various diseases. This review will be most useful for postgraduate dental students as well as scientists working in the field of oral pathology and oral medicine. PMID:26131314

Cooperative Control of Regenerative Braking and Antilock Braking for a Hybrid Electric Vehicle

Directory of Open Access Journals (Sweden)

Guodong Yin

2013-01-01

Full Text Available A new cooperative braking control strategy (CBCS is proposed for a parallel hybrid electric vehicle (HEV with both a regenerative braking system and an antilock braking system (ABS to achieve improved braking performance and energy regeneration. The braking system of the vehicle is based on a new method of HEV braking torque distribution that makes the antilock braking system work together with the regenerative braking system harmoniously. In the cooperative braking control strategy, a sliding mode controller (SMC for ABS is designed to maintain the wheel slip within an optimal range by adjusting the hydraulic braking torque continuously; to reduce the chattering in SMC, a boundary-layer method with moderate tuning of a saturation function is also investigated; based on the wheel slip ratio, battery state of charge (SOC, and the motor speed, a fuzzy logic control strategy (FLC is applied to adjust the regenerative braking torque dynamically. In order to evaluate the performance of the cooperative braking control strategy, the braking system model of a hybrid electric vehicle is built in MATLAB/SIMULINK. It is found from the simulation that the cooperative braking control strategy suggested in this paper provides satisfactory braking performance, passenger comfort, and high regenerative efficiency.

DanDan. Final report. [PEM fuel cells for back-up power and UPS]; DanDan. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-08-15

The project has provided valuable results for the partners involved, and has resulted in the construction and demonstration of a modular UPS system that can be used with fuel cells. Dantherm Power has provided a 5 kW fuel cell module, based on LT-pem technology, for use in the demonstration and testing facility. The function of the unit is verified by both internal testing and demonstrations from at third parties were it currently is set up to perform tests regarding lifetime. The development of a DC / DC converter, was made. The module has been tested under various conditions, and the development process has resulted in detailed specs of both technique and test process. The module has been tested both in laboratory environment and demonstrated at third parties. The module is part of the systems described in connection with initial test runs - performed at strategic partners - and in connection with the demonstration of the systems both in Japan and in South Africa. The modules are presently in a stage of demonstration, while subjected to substantial service life tests. The purchased reformers are part of the systems used for demonstration in the project and as such they will supply valuable data trough the comprehensive test and verification program initiated. (LN)

Thermodynamic study of a regenerative atmospheric water distiller; Estudo termodinamico de um destilador de agua atmosferico do tipo regenerativo

Energy Technology Data Exchange (ETDEWEB)

Costa, Gustavo Koury

1998-06-01

The need of water for human consumption in our region where there is a great storage of non saline sources has motivated the study of new desalination technologies. The present work introduces a water distiller whose main characteristic, in relation to other units, is the high production allied to a good efficiency. This equipment that promotes the reuse of the water condensation heat is then called Regenerative Distiller. A theoretical study of the thermodynamic process involved is made, resulting in a numeric model for the project of new units accordingly to the required demands. The theoretical results are also compared with experimental data obtained through the testing of prototype, built and put into operation by the FAE/DEN group of the Federal University of Pernambuco. (author)

The Hair Follicle: An Underutilized Source of Cells and Materials for Regenerative Medicine.

Science.gov (United States)

Kiani, Mehrdad T; Higgins, Claire A; Almquist, Benjamin D

2018-04-09

The hair follicle is one of only two structures within the adult body that selectively degenerates and regenerates, making it an intriguing organ to study and use for regenerative medicine. Hair follicles have been shown to influence wound healing, angiogenesis, neurogenesis, and harbor distinct populations of stem cells; this has led to cells from the follicle being used in clinical trials for tendinosis and chronic ulcers. In addition, keratin produced by the follicle in the form of a hair fiber provides an abundant source of biomaterials for regenerative medicine. In this review, we provide an overview of the structure of a hair follicle, explain the role of the follicle in regulating the microenvironment of skin and the impact on wound healing, explore individual cell types of interest for regenerative medicine, and cover several applications of keratin-based biomaterials.

Cooperative Control of Regenerative Braking and Antilock Braking for a Hybrid Electric Vehicle

OpenAIRE

Yin, Guodong; Jin, XianJian

2013-01-01

A new cooperative braking control strategy (CBCS) is proposed for a parallel hybrid electric vehicle (HEV) with both a regenerative braking system and an antilock braking system (ABS) to achieve improved braking performance and energy regeneration. The braking system of the vehicle is based on a new method of HEV braking torque distribution that makes the antilock braking system work together with the regenerative braking system harmoniously. In the cooperative braking control strategy, a sli...

Integrated high-efficiency Pt/carbon nanotube arrays for PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Weimin; Minett, Andrew I.; Zhao, Jie; Razal, Joselito M.; Wallace, Gordon G.; Romeo, Tony; Chen, Jun [Intelligent Polymer Research Institute, AIIM Facility, Innovation Campus, University of Wollongong, NSW 2522 (Australia); Gao, Mei [Division of Materials Science and Engineering, CSIRO, Bayview Ave, Clayton, VIC 3168 (Australia)

2011-07-15

A facile strategy to deposit Pt nanoparticles with various metal-loading densities on vertically aligned carbon nanotube (ACNT) arrays as electrocatalysts for proton exchange membrane (PEM) fuel cells is described. The deposition is achieved by electrostatic adsorption of the Pt precursor on the positively charged polyelectrolyte functionalized ACNT arrays and subsequent reduction by L-ascorbic acid. The application of the aligned electrocatalysts in fuel cells is realized by transferring from a quartz substrate to nafion membrane using a hot-press procedure to fabricate the membrane electrode assembly (MEA). It is shown that the MEA with vertically aligned structured electrocatalysts provides better Pt utilization than that with Pt on conventional carbon nanotubes or carbon black, resulting in higher fuel cell performance. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

HT-PEM Fuel Cell System with Integrated Thermoelectric Exhaust Heat Recovery

DEFF Research Database (Denmark)

Gao, Xin

This thesis presents two case studies on improving the efficiency and the loadfollowing capability of a high temperature polymer electrolyte membrane (HTPEM) fuel cell system by the application of thermoelectric (TE) devices. TE generators (TEGs) are harnessed to recover the system exhaust gas...... developed three-dimensional numerical model in ANSYS Fluent®. This thesis introduces the progress of this project in a cognitive order. The first chapter initially prepares the theory and characteristics of the fuel cell system and TE devices. Project motivations are conceived. Then similar studies existing...... power output on the subsystem design and performance were also systematically analyzed. The TEG subsystem configuration is optimized. The usefulness and convenience of the model are proved. TE coolers (TECs) are integrated into the methanol evaporator of the HT-PEM system for improving the whole system...

MicroRNA Delivery for Regenerative Medicine

OpenAIRE

Peng, Bo; Chen, Yongming; Leong, Kam W.

2015-01-01

MicroRNA (miRNA) directs post-transcriptional regulation of a network of genes by targeting mRNA. Although relatively recent in development, many miRNAs direct differentiation of various stem cells including induced pluripotent stem cells (iPSCs), a major player in regenerative medicine. An effective and safe delivery of miRNA holds the key to translating miRNA technologies. Both viral and nonviral delivery systems have seen success in miRNA delivery, and each approach possesses advantages an...

A numerical study of the gas-liquid, two-phase flow maldistribution in the anode of a high pressure PEM water electrolysis cell

DEFF Research Database (Denmark)

Olesen, Anders Christian; Rømer, Carsten; Kær, Søren Knudsen

2016-01-01

In this work, the use of a circular-planar, interdigitated flow field for the anode of a high pressure proton exchange membrane (PEM) water electrolysis cell is investigated in a numerical study. While PEM fuel cells have separated flow fields for reactant transport and coolant, it is possible...... causes maldistribution, if land areas of equal width are applied. Moreover, below a water stoichiometry of 350, and at a current density of 1 A/cm2, flow and temperature maldistribution is adversely affected by the presence of the gas phase; particularly gas hold-up near outlet channels can cause......-phase flow model for establishing the effect of geometry and a two-phase flow model for studying the effect of dispersed gas bubbles. Both models account for turbulence and heat transport. By means of the developed models, it is elucidated that the circular-planar shape of the interdigitated flow field...

STUDY ON ENERGY EXCHANGE PROCESSES IN NORMAL OPERATION OF METRO ROLLING STOCK WITH REGENERATIVE BRAKING SYSTEMS

Directory of Open Access Journals (Sweden)

A. O. Sulym

2017-10-01

Full Text Available Purpose. The analysis of the existing studies showed that the increasing of energy efficiency of metro rolling stock becomes especially important and requires timely solutions. It is known that the implementation of regenerative braking systems on rolling stock will allow significantly solving this problem. It was proved that one of the key issues regarding the introduction of the above-mentioned systems is research on efficient use of electric energy of regenerative braking. The purpose of the work is to evaluate the amount of excessive electric power of regenerative braking under normal operation conditions of the rolling stock with regenerative braking systems for the analysis of the energy saving reserves. Methodology. Quantifiable values of electrical energy consumed for traction, returned to the contact line and dissipated in braking resistors (excessive energy are determined using results of experimental studies of energy exchange processes under normal operating conditions of metro rolling stock with regenerative systems. Statistical methods of data processing were applied as well. Findings. Results of the studies analysis of metro rolling stock operation under specified conditions in Sviatoshinsko-Brovarskaia line of KP «Kyiv Metro system» stipulate the following: 1 introduction of regenerative braking systems into the rolling stock allows to return about 17.9-23.2% of electrical energy consumed for traction to the contact line; 2 there are reserves for improving of energy efficiency of rolling stock with regenerative systems at the level of 20.2–29.9 % of electrical energy consumed for traction. Originality. For the first time, it is proved that the most significant factor that influences the quantifiable values of the electrical energy regeneration is a track profile. It is suggested to use coefficients which indicate the amount and reserves of unused (excessive electrical energy for quantitative evaluation. Studies on

Materials Challenges for Automotive PEM Fuel Cells

Science.gov (United States)

Gasteiger, Hubert

2004-03-01

Over the past few years, significant R efforts aimed at meeting the challenging cost and performance targets required for the use of Polymer Electrolyte Membrane (PEM) fuel cells in automotive applications. Besides engineering advances in bipolar plate materials and design, the optimization of membrane-electrode assemblies (MEAs) was an important enabler in reducing the cost and performance gaps towards commercial viability for the automotive market. On the one hand, platinum loadings were reduced from several mgPt/cm2MEA [1] to values of 0.5-0.6 mgPt/cm2MEA in current applications and loadings as low as 0.25 mgPt/cm2MEA have been demonstrated on the research level [2]. On the other hand, implementation of thin membranes (20-30 micrometer) [3, 4] as well as improvements in diffusion medium materials, essentially doubled the achievable power density of MEAs to ca. 0.9 W/cm2MEA (at 0.65 V) [5], thereby not only reducing the size of a PEMFC fuel cell system, but also reducing its overall materials cost (controlled to a large extent by membrane and Pt-catalyst cost). While this demonstrated a clear path towards automotive applications, a renewed focus of R efforts is now required to develop materials and fundamental materials understanding to assure long-term durability of PEM fuel cells. This presentation therefore will discuss the state-of-the-art knowledge of catalyst, catalyst-support, and membrane degradation mechanisms. In the area of Pt-catalysts, experience with phosphoric acid fuel cells (PAFCs) has shown that platinum sintering leads to long-term performance losses [6]. While this is less critical at the lower PEMFC operating temperatures (200C), very little is known about the dependence of Pt-sintering on temperature, cell voltage, and catalyst type (i.e., Pt versus Pt-alloys) and will be discussed here. Similarly, carbon-support corrosion can contribute significantly to voltage degradation in PAFCs [7], and even in the PEMFC environment more corrosion

Design and Control of High Temperature PEM Fuel Cell System

DEFF Research Database (Denmark)

Andreasen, Søren Juhl

E-cient fuel cell systems have started to appear in many dierent commercial applications and large scale production facilities are already operating to supply fuel cells to support an ever growing market. Fuel cells are typically considered to replace leadacid batteries in applications where...... to conventional PEM fuel cells, that use liquid water as a proton conductor and thus operate at temperatures below 100oC. The HTPEM fuel cell membrane in focus in this work is the BASF Celtec-P polybenzimidazole (PBI) membrane that uses phosphoric acid as a proton conductor. The absence of water in the fuel cells...... enables the use of designing cathode air cooled stacks greatly simplifying the fuel cell system and lowering the parasitic losses. Furthermore, the fuel impurity tolerance is signicantly improved because of the higher temperatures, and much higher concentrations of CO can be endured without performance...

Performance of the PdNi and PdNiSe as cathodes in PEM fuel cells; Desempeno de PdNi y PdNiSe como catodos en celdas de combustible tipo PEM

Energy Technology Data Exchange (ETDEWEB)

Santana, A.; Ramos-Sanchez, G.; Vazquez, G.; Solorza-Feria, O. [Centro de Investigaciones y de Estudios Avanzados del IPN, Mexico D.F. (Mexico)]. E-mail: gramos@cinvestav.mx

2009-09-15

The search for new materials capable of catalyzing oxygen reactions in low temperature fuel cells continues to be one of the key issues in the development of a hydrogen economy. Electrochemical and physical characterization studies have demonstrated that the PdNi and PdNiSe catalysts have adequate properties for use as cathodes in fuel cells. Nevertheless, the performance of the materials in proton exchange membrane (PEM) fuel cells depends not only on the catalytic properties but also on the adequate preparation of the electrocatalyst membrane interface (EMI). This work presents the results of the search for optimal conditions to prepare the EMIs with PdNi and PdNiSe cathodes. There are many variables for handling the preparation of the interfaces, nevertheless our search focuses on two: catalyst ratio/Vulcan Carbon® and the catalyst amount. Interfaces were prepared with an active area of 5 cm{sup 2} with PdNi and PdNiSe cathodes and carbon fabric anode with Pt E-tek®. These interfaces were tested with an ElectroChem model under different gas pressure and temperature conditions. The optimization method was carried out using a simplex method with the variables mentioned above and power density per unit mass and catalyst area as response variables. [Spanish] La busqueda de nuevos materiales capaces de catalizar la Reaccion de Oxigeno (RRO) en celdas de combustible de baja temperatura, sigue siendo uno de los temas clave para el desarrollo de una Economia del Hidrogeno. Estudios electroquimicos y de caracterizacion fisica han demostrado que los catalizadores PdNi y PdNiSe, tienen las propiedades adecuadas para poder ser utilizados como catodos en celdas de combustible; sin embargo el desempeno de los materiales en celdas de combustible de membrana de intercambio protonico (PEM), no solo depende de las propiedades del catalizador, sino tambien de la preparacion adecuada del Ensamble Membrana Electrocatalizador (EME). En este trabajo se presentan los resultados de la

Carbon monoxide tolerant anodes for proton exchange membrane (PEM) fuel cells. 1. Catalyst development approach

Energy Technology Data Exchange (ETDEWEB)

Holleck, G L; Pasquariello, D M; Clauson, S L

1998-07-01

PEM fuel cells are highly attractive for distributed power and cogeneration systems. They are efficient and function virtually without noise or pollution. To be competitive PEM fuel cells must operate on fuel mixtures obtained by reforming of widely available natural gas or liquid hydrocarbons. Reformed fuel gas mixtures invariably contain CO, a strong poison for Pt. Therefore CO tolerant anode catalysts are essential for wide spread PEMFC introduction. It is the objective to develop effective CO tolerant fuel cell catalysts based on multi-component platinum-transition metal alloys. Towards this goal the authors have developed a novel approach for the synthesis and performance evaluation of multifunctional ternary alloy fuel cell catalysts. The alloys are prepared as well-defined thin films on standard TFE-bonded carbon substrates via a dc magnetron sputtering technique. The anodes are laminated to Nafion membranes and the electrochemical performance is measured in a representative fuel cell configuration with H{sub 2} and H{sub 2}/CO gas mixtures. The multi-target sputtering technique permits one to reproducibly synthesize true alloy films of controlled composition. The deposit morphology and electrode structure are determined by the standardized TFE bonded carbon substrate. The thin catalyst layer is concentrated at the electrode ionomer interface where it can be fully utilized in a representative fuel cell configuration. Thus, a true comparative fuel cell catalyst evaluation is possible. The effectiveness of this approach will be demonstrated with Pt, Pt-Ru and Pt-Ru-X catalyzed anodes.

Performance Analysis of Regenerative Braking in Permanent Magnet Synchronous Motor Drives

Directory of Open Access Journals (Sweden)

Andrew Adib

2018-02-01

Full Text Available This paper describes the design and analysis of a regenerative braking system for a permanent magnet synchronous motor (PMSM drive for electric vehicle (EV applications. First studied is the principle for electric braking control of a PMSM motor under field-oriented control (FOC. Next, the maximum braking torque in the regeneration mode as well as the braking torque for the maximum regeneration power, respectively, are deduced. Additionally, an optimum switching scheme for the inverter is developed with the objective of maximizing energy recovery during regenerative braking to the DC-bus capacitor. The integration of an ultra-capacitor module with the battery allows for the efficient and high power transfer under regenerative braking. It was important to manage the power flow to the DC-bus as this is a key issue that affects the efficiency of the overall system. Finally, the amounts of braking energy that can be recovered, and the efficiency with which it can be returned to the battery/ultra-capacitor, is analyzed for a PMSM coupled with a DC motor as the load. The results of the analysis are validated through experimentation.

Experimental Analysis of the Effects of CO and CO2 on High Temperature PEM Fuel Cell Performance using Electrochemical Impedance Spectroscopy

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Vang, Jakob Rabjerg

2010-01-01

The use of high temperature PEM (HTPEM) fuel cells running on reformate gas shows comparable performance to HTPEM fuel cells running on pure hydrogen, even when running at high levels of CO, as long as high operating temperatures are ensured. The increased operating temperatures of these types of...

Regenerative braking strategies, vehicle safety and stability control systems: critical use-case proposals

Science.gov (United States)

Oleksowicz, Selim A.; Burnham, Keith J.; Southgate, Adam; McCoy, Chris; Waite, Gary; Hardwick, Graham; Harrington, Cian; McMurran, Ross

2013-05-01

The sustainable development of vehicle propulsion systems that have mainly focused on reduction of fuel consumption (i.e. CO2 emission) has led, not only to the development of systems connected with combustion processes but also to legislation and testing procedures. In recent years, the low carbon policy has made hybrid vehicles and fully electric vehicles (H/EVs) popular. The main virtue of these propulsion systems is their ability to restore some of the expended energy from kinetic movement, e.g. the braking process. Consequently new research and testing methods for H/EVs are currently being developed. This especially concerns the critical 'use-cases' for functionality tests within dynamic events for both virtual simulations, as well as real-time road tests. The use-case for conventional vehicles for numerical simulations and road tests are well established. However, the wide variety of tests and their great number (close to a thousand) creates a need for selection, in the first place, and the creation of critical use-cases suitable for testing H/EVs in both virtual and real-world environments. It is known that a marginal improvement in the regenerative braking ratio can significantly improve the vehicle range and, therefore, the economic cost of its operation. In modern vehicles, vehicle dynamics control systems play the principal role in safety, comfort and economic operation. Unfortunately, however, the existing standard road test scenarios are insufficient for H/EVs. Sector knowledge suggests that there are currently no agreed tests scenarios to fully investigate the effects of brake blending between conventional and regenerative braking as well as the regenerative braking interaction with active driving safety systems (ADSS). The paper presents seven manoeuvres, which are considered to be suitable and highly informative for the development and examination of H/EVs with regenerative braking capability. The critical manoeuvres presented are considered to be

Regenerative Endodontic Treatment: Report of Two Cases with Different Clinical Management and Outcomes

Directory of Open Access Journals (Sweden)

Mehrfam Khoshkhounejad

2015-11-01

Full Text Available Endodontic intervention in necrotic immature permanent teeth is usually a clinical challenge. With appropriate case selection, regenerative treatment can be effective, providing a desirable outcome. However, there is still no consensus on the optimal disinfection protocol or the method to achieve predictable clinical outcome. This article presents two cases of regenerative treatment in necrotic immature teeth, using mineral trioxide aggregate (MTA and BiodentineTM as coronal barriers and different irrigants, which led to different clinical outcomes.

Advances in individualized and regenerative medicine.

Science.gov (United States)

Blum, Hubert E

2014-03-01

Molecular and cell biology have resulted in major advances in our understanding of disease pathogenesis as well as in novel strategies for the diagnosis, therapy and prevention of human diseases. Based on modern molecular, genetic and biochemical methodologies it is on the one hand possible to identify for example disease-related point mutations and single nucleotide polymorphisms. On the other hand, using high throughput array and other technologies, it is for example possible to simultaneously analyze thousands of genes or gene products (RNA and proteins), resulting in an individual gene or gene expression profile ('signature'). Such data increasingly allow to define the individual disposition for a given disease and to predict disease prognosis as well as the efficacy of therapeutic strategies in the individual patient ('individualized medicine'). At the same time, the basic discoveries in cell biology, including embryonic and adult stem cells, induced pluripotent stem cells, genetically modified cells and others, have moved regenerative medicine into the center of biomedical research worldwide with a major translational impact on tissue engineering as well as transplantation medicine. All these aspects have greatly contributed to the recent advances in regenerative medicine and the development novel concepts for the treatment of many human diseases, including liver diseases. Copyright © 2014 Medical University of Bialystok. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Research on motor rotational speed measurement in regenerative braking system of electric vehicle

Science.gov (United States)

Pan, Chaofeng; Chen, Liao; Chen, Long; Jiang, Haobin; Li, Zhongxing; Wang, Shaohua

2016-01-01

Rotational speed signals acquisition and processing techniques are widely used in rotational machinery. In order to realized precise and real-time control of motor drive and regenerative braking process, rotational speed measurement techniques are needed in electric vehicles. Obtaining accurate motor rotational speed signal will contribute to the regenerative braking force control steadily and realized higher energy recovery rate. This paper aims to develop a method that provides instantaneous speed information in the form of motor rotation. It addresses principles of motor rotational speed measurement in the regenerative braking systems of electric vehicle firstly. The paper then presents ideal and actual Hall position sensor signals characteristics, the relation between the motor rotational speed and the Hall position sensor signals is revealed. Finally, Hall position sensor signals conditioning and processing circuit and program for motor rotational speed measurement have been carried out based on measurement error analysis.

Vehicle State Estimator based regenerative braking implementation on an electric vehicle to improve lateral vehicle stability

NARCIS (Netherlands)

Jansen, S.T.H.; van Boekel, J.J.P.; Iersel, van S.S.; Besselink, I.J.M.; Nijmeijer, H.

2013-01-01

The driving range of electric vehicles can be extended using regenerative braking. Regenerative braking uses the electric drive system, and therefore only the driven wheels, for decelerating the vehicle. Braking on one axle affects the stability of the vehicle, especially for road conditions with

Vehicle state estimator based regenerative braking implementation on an electric vehicle to improve lateral vehicle stability

NARCIS (Netherlands)

Jansen, S.T.H.; Boekel, J.J.P. van; Iersel, S.S. van; Besselink, I.J.M.; Nijmeijer, H.

2013-01-01

The driving range of electric vehicles can be extended using regenerative braking. Regenerative braking uses the elctric drive system, and therefore only the driven wheels, for decelerating the vehicle. Braking on one axle affects the stability of the vehicle, especially for road conditions with

Introduction to regenerative medicine and tissue engineering.

Science.gov (United States)

Stoltz, J-F; Decot, V; Huseltein, C; He, X; Zhang, L; Magdalou, J; Li, Y P; Menu, P; Li, N; Wang, Y Y; de Isla, N; Bensoussan, D

2012-01-01

Human tissues don't regenerate spontaneously, explaining why regenerative medicine and cell therapy represent a promising alternative treatment (autologous cells or stem cells of different origins). The principle is simple: cells are collected, expanded and introduced with or without modification into injured tissues or organs. Among middle-term therapeutic applications, cartilage defects, bone repair, cardiac insufficiency, burns, liver or bladder, neurodegenerative disorders could be considered.

A solar regenerative thermoelectrochemical converter (RTEC)

Energy Technology Data Exchange (ETDEWEB)

Townsend, C.W.; McHardy, J. (Hughes Aircraft Co., El Segundo, CA (United States))

1992-02-01

This is an executive summary of a final subcontract report that describes the successful completion of a closed-loop demonstration of a regenerative thermoelectromechanical device using solar heat input for the production of electricity. The full report, which contains a detailed description of the two-year effort, is currently subject to a government secrecy order which precludes public release of the information. Copies of the full report will be made available for general release whenever the secrecy order is lifted.

Distribution of the Current Density in Electrolyte of the Pem Fuel Cell

Directory of Open Access Journals (Sweden)

Eugeniusz Kurgan

2004-01-01

Full Text Available In this paper water management in proton exchange membrane (PEM fuel cell is considered. Firt mass convervation law for water is applied. Next proton transport is described by the Nernst-Planck equation and liqid water convection velocity is eliminated by the Schlogl equation. Electro-osmotic drag coefficient is related to hydrogen index and experimentally determined swelling coefficient. Three partial differential equations for molar water concentration Cw, electric potential ϕ and water pressure Pw are formulated. Current density vector i is derived from proton flux expression. These equations together with adequate boundary conditions were solved using finite element method. The distribution of electric potential and current density in function of geometrical parametres is investigated. At the end some illustrative example is given.

Distributed generation system with PEM fuel cell for electrical power quality improvement

Energy Technology Data Exchange (ETDEWEB)

Ramirez, D.; Beites, L.F.; Blazquez, F. [Department of Electrical Engineering, ETSII, Escuela de Ingenieros Industriales, Universidad Politecnica de Madrid, C/ Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Ballesteros, J.C. [Endesa Generacion, S.A. c/ Ribera de Loira 60, 28042 Madrid (Spain)

2008-08-15

In this paper, a physical model for a distributed generation (DG) system with power quality improvement capability is presented. The generating system consists of a 5 kW PEM fuel cell, a natural gas reformer, hydrogen storage bottles and a bank of ultra-capacitors. Additional power quality functions are implemented with a vector-controlled electronic converter for regulating the injected power. The capabilities of the system were experimentally tested on a scaled electrical network. It is composed of different lines, built with linear inductances and resistances, and taking into account both linear and non-linear loads. The ability to improve power quality was tested by means of different voltage and frequency perturbations produced on the physical model electrical network. (author)

Mechanical cues in orofacial tissue engineering and regenerative medicine

NARCIS (Netherlands)

Brouwer, K.M.; Lundvig, D.M.S.; Middelkoop, E.; Wagener, F.A.D.T.; Von den Hoff, J.W.

2015-01-01

Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of

Numerical Study of the Dynamic Response of Heat and Mass Transfer to Operation Mode Switching of a Unitized Regenerative Fuel Cell

Directory of Open Access Journals (Sweden)

Hong Xiao

2016-12-01

Full Text Available Knowledge concerning the complicated changes of mass and heat transfer is desired to improve the performance and durability of unitized regenerative fuel cells (URFCs. In this study, a transient, non-isothermal, single-phase, and multi-physics mathematical model for a URFC based on the proton exchange membrane is generated to investigate transient responses in the process of operation mode switching from fuel cell (FC to electrolysis cell (EC. Various heat generation mechanisms, including Joule heat, reaction heat, and the heat attributed to activation polarizations, have been considered in the transient model coupled with electrochemical reaction and mass transfer in porous electrodes. The polarization curves of the steady-state models are validated by experimental data in the literatures. Numerical results reveal that current density, gas mass fractions, and temperature suddenly change with the sudden change of operating voltage in the mode switching process. The response time of temperature is longer than that of current density and gas mass fractions. In both FC and EC modes, the cell temperature and gradient of gas mass fraction in the oxygen side are larger than that in the hydrogen side. The temperature difference of the entire cell is less than 1.5 K. The highest temperature appears at oxygen-side catalyst layer under the FC mode and at membrane under a more stable EC mode. The cell is exothermic all the time. These dynamic responses and phenomena have important implications for heat analysis and provide proven guidelines for the improvement of URFCs mode switching.