Investigation of grafted ETFE-based polymer membranes as alternative electrolyte for direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Aricò, A. S.; Baglio, V.; Cretı̀, P.; Di Blasi, A.; Antonucci, V.; Brunea, J.; Chapotot, A.; Bozzi, A.; Schoemans, J.

Low cost ethylene-tetrafluoroethylene (ETFE)-based grafted membranes have been prepared by a process based on electron beam irradiation, subsequent grafting, cross-linking and sulfonation procedure. Two different grafted membranes varying by their grafting and cross-linking levels have been investigated for applications in direct methanol fuel cells (DMFCs) operating between 90 and 130 °C. DMFC assemblies based on these membranes showed cell resistance and performance values comparable to Nafion 117. Stable electrochemical performance was recorded during 1 month of cycled operation. Tailoring of grafting and cross-linking properties allows a significant reduction of methanol cross-over while maintaining suitable conductivity and performance levels.

Morphological observation and analysis using automated image cytometry for the comparison of trypan blue and fluorescence-based viability detection method.

PubMed

Chan, Leo Li-Ying; Kuksin, Dmitry; Laverty, Daniel J; Saldi, Stephanie; Qiu, Jean

2015-05-01

The ability to accurately determine cell viability is essential to performing a well-controlled biological experiment. Typical experiments range from standard cell culturing to advanced cell-based assays that may require cell viability measurement for downstream experiments. The traditional cell viability measurement method has been the trypan blue (TB) exclusion assay. However, since the introduction of fluorescence-based dyes for cell viability measurement using flow or image-based cytometry systems, there have been numerous publications comparing the two detection methods. Although previous studies have shown discrepancies between TB exclusion and fluorescence-based viability measurements, image-based morphological analysis was not performed in order to examine the viability discrepancies. In this work, we compared TB exclusion and fluorescence-based viability detection methods using image cytometry to observe morphological changes due to the effect of TB on dead cells. Imaging results showed that as the viability of a naturally-dying Jurkat cell sample decreased below 70 %, many TB-stained cells began to exhibit non-uniform morphological characteristics. Dead cells with these characteristics may be difficult to count under light microscopy, thus generating an artificially higher viability measurement compared to fluorescence-based method. These morphological observations can potentially explain the differences in viability measurement between the two methods.

Dopant-Free Tetrakis-Triphenylamine Hole Transporting Material for Efficient Tin-Based Perovskite Solar Cells.

PubMed

Ke, Weijun; Priyanka, Pragya; Vegiraju, Sureshraju; Stoumpos, Constantinos C; Spanopoulos, Ioannis; Soe, Chan Myae Myae; Marks, Tobin J; Chen, Ming-Chou; Kanatzidis, Mercouri G

2018-01-10

Developing dopant-free hole transporting layers (HTLs) is critical in achieving high-performance and robust state-of-the-art perovskite photovoltaics, especially for the air-sensitive tin-based perovskite systems. The commonly used HTLs require hygroscopic dopants and additives for optimal performance, which adds extra cost to manufacturing and limits long-term device stability. Here we demonstrate the use of a novel tetrakis-triphenylamine (TPE) small molecule prepared by a facile synthetic route as a superior dopant-free HTL for lead-free tin-based perovskite solar cells. The best-performing tin iodide perovskite cells employing the novel mixed-cation ethylenediammonium/formamidinium with the dopant-free TPE HTL achieve a power conversion efficiency as high as 7.23%, ascribed to the HTL's suitable band alignment and excellent hole extraction/collection properties. This efficiency is one of the highest reported so far for tin halide perovskite systems, highlighting potential application of TPE HTL material in low-cost high-performance tin-based perovskite solar cells.

Novel metamaterials and their applications in subwavelength waveguides, imanging and modulation

NASA Astrophysics Data System (ADS)

Zhang, Chaomin

GaAs-based solar cells have attracted much interest because of their high conversion efficiencies of ~28% under one sun illumination. The main carrier recombination mechanisms in the GaAs-based solar cells are surface recombination, radiative recombination and non-radiative recombination. Photon recycling reduces the effect of radiative recombination and is an approach to obtain the device performance described by detailed balance theory. The photon recycling model has been developed and was applied to investigate the loss mechanisms in the state-of-the-art GaAs-based solar cell structures using PC1D software. A standard fabrication process of the GaAs-based solar cells is as follows: wafer preparation, individual cell isolation by mesa, n- and p-type metallization, rapid thermal annealing (RTA), cap layer etching, and anti-reflection coating (ARC). The growth rate for GaAs-based materials is one of critical factors to determine the cost for the growth of GaAs-based solar cells. The cost for fabricating GaAs-based solar cells can be reduced if the growth rate is increased without degrading the crystalline quality. The solar cell wafers grown at different growth rates of 14 mum/hour and 55 mum/hour were discussed in this work. The structural properties of the wafers were characterized by X-ray diffraction (XRD) to identify the crystalline quality, and then the as-grown wafers were fabricated into solar cell devices under the same process conditions. The optical and electrical properties such as surface reflection, external quantum efficiency (EQE), dark I-V, Suns-Voc, and illuminated I-V under one sun using a solar simulator were measured to compare the performances of the solar cells with different growth rates. Some simulations in PC1D have been demonstrated to investigate the reasons of the different device performances between fast growth and slow growth structures. A further analysis of the minority carrier lifetime is needed to investigate into the difference in device performances.

High-efficiency single cell encapsulation and size selective capture of cells in picoliter droplets based on hydrodynamic micro-vortices.

PubMed

Kamalakshakurup, Gopakumar; Lee, Abraham P

2017-12-05

Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of the primary challenges for droplet based single cell assays is single cell encapsulation in droplets, currently achieved either randomly, dictated by Poisson statistics, or by hydrodynamic techniques. In this paper, we present an interfacial hydrodynamic technique which initially traps the cells in micro-vortices, and later releases them one-to-one into the droplets, controlled by the width of the outer streamline that separates the vortex from the flow through the streaming passage adjacent to the aqueous-oil interface (d gap ). One-to-one encapsulation is achieved at a d gap equal to the radius of the cell, whereas complete trapping of the cells is realized at a d gap smaller than the radius of the cell. The unique feature of this technique is that it can perform 1. high efficiency single cell encapsulations and 2. size-selective capturing of cells, at low cell loading densities. Here we demonstrate these two capabilities with a 50% single cell encapsulation efficiency and size selective separation of platelets, RBCs and WBCs from a 10× diluted blood sample (WBC capture efficiency at 70%). The results suggest a passive, hydrodynamic micro-vortex based technique capable of performing high-efficiency single cell encapsulation for cell based assays.

Performance of PCR-based and Bioluminescent assays for mycoplasma detection.

PubMed

Falagan-Lotsch, Priscila; Lopes, Talíria Silva; Ferreira, Nívea; Balthazar, Nathália; Monteiro, Antônio M; Borojevic, Radovan; Granjeiro, José Mauro

2015-11-01

Contaminated eukaryotic cell cultures are frequently responsible for unreliable results. Regulatory entities request that cell cultures must be mycoplasma-free. Mycoplasma contamination remains a significant problem for cell cultures and may have an impact on biological analysis since they affect many cell parameters. The gold standard microbiological assay for mycoplasma detection involves laborious and time-consuming protocols. PCR-based and Bioluminescent assays have been considered for routine cell culture screening in research laboratories since they are fast, easy and sensitive. Thus, the aim of this work is to compare the performance of two popular commercial assays, PCR-based and Bioluminescent assays, by assessing the level of mycoplasma contamination in cell cultures from Rio de Janeiro Cell Bank (RJCB) and also from customers' laboratories. The results obtained by both performed assays were confirmed by scanning electron microscopy. In addition, we evaluated the limit of detection of the PCR kit under our laboratory conditions and the storage effects on mycoplasma detection in frozen cell culture supernatants. The performance of both assays for mycoplasma detection was not significantly different and they showed very good agreement. The Bioluminescent assay for mycoplasma detection was slightly more dependable than PCR-based due to the lack of inconclusive results produced by the first technique, especially considering the ability to detect mycoplasma contamination in frozen cell culture supernatants. However, cell lines should be precultured for four days or more without antibiotics to obtain safe results. On the other hand, a false negative result was obtained by using this biochemical approach. The implementation of fast and reliable mycoplasma testing methods is an important technical and regulatory issue and PCR-based and Bioluminescent assays may be good candidates. However, validation studies are needed. Copyright © 2015 Elsevier B.V. All rights reserved.

Optoelectrical modeling of solar cells based on c-Si/a-Si:H nanowire array: focus on the electrical transport in between the nanowires.

PubMed

Levtchenko, Alexandra; Le Gall, Sylvain; Lachaume, Raphaël; Michallon, Jérôme; Collin, Stéphane; Alvarez, José; Djebbour, Zakaria; Kleider, Jean-Paul

2018-06-22

By coupling optical and electrical modeling, we have investigated the photovoltaic performances of p-i-n radial nanowires array based on crystalline p-type silicon (c-Si) core/hydrogenated amorphous silicon (a-Si:H) shell. By varying either the doping concentration of the c-Si core, or back contact work function we can separate and highlight the contribution to the cell's performance of the nanowires themselves (the radial cell) from the interspace between the nanowires (the planar cell). We show that the build-in potential (V bi ) in the radial and planar cells strongly depends on the doping of c-Si core and the work function of the back contact respectively. Consequently, the solar cell's performance is degraded if either the doping concentration of the c-Si core, or/and the work function of the back contact is too low. By inserting a thin (p) a-Si:H layer between both core/absorber and back contact/absorber, the performance of the solar cell can be improved by partly fixing the V bi at both interfaces due to strong electrostatic screening effect. Depositing such a buffer layer playing the role of an electrostatic screen for charge carriers is a suggested way of enhancing the performance of solar cells based on radial p-i-n or n-i-p nanowire array.

High Performance Fuel Cell and Electrolyzer Membrane Electrode Assemblies (MEAs) for Space Energy Storage Systems

NASA Technical Reports Server (NTRS)

Valdez, Thomas I.; Billings, Keith J.; Kisor, Adam; Bennett, William R.; Jakupca, Ian J.; Burke, Kenneth; Hoberecht, Mark A.

2012-01-01

Regenerative fuel cells provide a pathway to energy storage system development that are game changers for NASA missions. The fuel cell/ electrolysis MEA performance requirements 0.92 V/ 1.44 V at 200 mA/cm2 can be met. Fuel Cell MEAs have been incorporated into advanced NFT stacks. Electrolyzer stack development in progress. Fuel Cell MEA performance is a strong function of membrane selection, membrane selection will be driven by durability requirements. Electrolyzer MEA performance is catalysts driven, catalyst selection will be driven by durability requirements. Round Trip Efficiency, based on a cell performance, is approximately 65%.

Structural studies of enzyme-based microfluidic biofuel cells

NASA Astrophysics Data System (ADS)

Togo, Makoto; Takamura, Akimasa; Asai, Tatsuya; Kaji, Hirokazu; Nishizawa, Matsuhiko

An enzyme-based glucose/O 2 biofuel cell was constructed within a microfluidic channel to study the influence of electrode configuration and fluidic channel height on cell performance. The cell was composed of a bilirubin oxidase (BOD)-adsorbed O 2 cathode and a glucose anode prepared by co-immobilization of glucose dehydrogenase (GDH), diaphorase (Dp) and VK 3-pendant poly- L-lysine. The consumption of O 2 at the upstream cathode protected the downstream anode from interfering O 2 molecules, and consequently improved the cell performance (maximum cell current) ca. 10% for the present cell. The cell performance was also affected by the channel height. The output current and power of a 0.1 mm-height cell was significantly less than those of a 1 mm-height cell because of the depletion of O 2, as determined by the shape of the E- I curve at the cathode. On the other hand, the volume density of current and power was several times higher for the narrower cell.

Research Update: Comparison of salt- and molecular-based iodine treatments of PbS nanocrystal solids for solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jähnig, Fabian; Bozyigit, Deniz; Yarema, Olesya

2015-02-01

Molecular- and salt-based chemical treatments are believed to passivate electronic trap states in nanocrystal-based semiconductors, which are considered promising for solar cells but suffer from high carrier recombination. Here, we compare the chemical, optical, and electronic properties of PbS nanocrystal-based solids treated with molecular iodine and tetrabutylammonium iodide. Surprisingly, both treatments increase—rather than decrease—the number density of trap states; however, the increase does not directly influence solar cell performance. We explain the origins of the observed impact on solar cell performance and the potential in using different chemical treatments to tune charge carrier dynamics in nanocrystal-solids.

MnROAD cells 16-23 (phase II) : forensic investigation into recycled unbound base and asphalt surface materials.

DOT National Transportation Integrated Search

2017-06-01

This report presents the findings from an eight-year performance evaluation of eight cells (Cells 16-23) built at the Minnesota Road Research Facility (MnROAD) in 2008. The constructed cells were used for two performance evaluation studies of: 1) unb...

Empirical correlations of the performance of vapor-anode PX-series AMTEC cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, L.; Merrill, J.M.; Mayberry, C.

Power systems based on AMTEC technology will be used for future NASA missions, including a Pluto-Express (PX) or Europa mission planned for approximately year 2004. AMTEC technology may also be used as an alternative to photovoltaic based power systems for future Air Force missions. An extensive development program of Alkali-Metal Thermal-to-Electric Conversion (AMTEC) technology has been underway at the Vehicle Technologies Branch of the Air Force Research Laboratory (AFRL) in Albuquerque, New Mexico since 1992. Under this program, numerical modeling and experimental investigations of the performance of the various multi-BASE tube, vapor-anode AMTEC cells have been and are being performed.more » Vacuum testing of AMTEC cells at AFRL determines the effects of changing the hot and cold end temperatures, T{sub hot} and T{sub cold}, and applied external load, R{sub ext}, on the cell electric power output, current-voltage characteristics, and conversion efficiency. Test results have traditionally been used to provide feedback to cell designers, and to validate numerical models. The current work utilizes the test data to develop empirical correlations for cell output performance under various working conditions. Because the empirical correlations are developed directly from the experimental data, uncertainties arising from material properties that must be used in numerical modeling can be avoided. Empirical correlations of recent vapor-anode PX-series AMTEC cells have been developed. Based on AMTEC theory and the experimental data, the cell output power (as well as voltage and current) was correlated as a function of three parameters (T{sub hot}, T{sub cold}, and R{sub ext}) for a given cell. Correlations were developed for different cells (PX-3C, PX-3A, PX-G3, and PX-5A), and were in good agreement with experimental data for these cells. Use of these correlations can greatly reduce the testing required to determine electrical performance of a given type of AMTEC cell over a wide range of operating conditions.« less

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

NASA Technical Reports Server (NTRS)

Baldwin, Richard S.; Bennett, William R.

2007-01-01

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

Roles of Fullerene-Based Interlayers in Enhancing the Performance of Organometal Perovskite Thin-Film Solar Cells

DOE PAGES

Liang, Po-Wei; Chueh, Chu-Chen; Williams, Spencer T.; ...

2015-02-27

Roles of fullerene-based interlayers in enhancing the performance of organometal perovskite thin-film solar cells are elucidated. By studying various fullerenes, a clear correlation between the electron mobility of fullerenes and the resulting performance of derived devices is determined. The metallic characteristics of the bilayer perovskite/fullerene field-effect transistor indicates an effective charge redistribution occurring at the corresponding interface. Lastly, a conventional perovskite thin-film solar cell derived from the C 60 electron-transporting layer (ETL) affords a high power conversion efficiency of 15.4%.

Analyses of Nb-1Zr/C-103, vapor anode, multi-tube AMTEC cells

NASA Astrophysics Data System (ADS)

King, Jeffrey C.; El-Genk, Mohamed S.

2000-01-01

A high performance, Nb-1Zr/C-103, vapor anode, multi-tube AMTEC cell design is presented. The cell measures 41.27 mm in diameter, is 125.3 mm high, and has eight BASE tubes connected electrically in series. The hot structure of the cell (hot plate, BASE tubes support plate, hot plenum wall, evaporator standoff, evaporator wick, and side wall facing the BASE tubes) is made of Nb-1Zr. The cold structure of the cell (condenser, interior cylindrical thermal radiation shield, the casing and the wick of the liquid sodium return artery, and side wall above the BASE tubes) is made of the stronger, lower thermal conductivity niobium alloy C-103. This cell, which weighs 163.4 g, could deliver 7.0 We at 17% efficiency and load voltage of 3.3 V, when using TiN BASE electrodes characterized by B=75 A.K1/2/m2.Pa and G=50 and assuming BASE/electrode contact resistance of 0.06 Ω-cm2 and leakage resistance of the BASE braze structure of 3 Ω. For these performance parameters and when the interior cylindrical C-103 thermal radiation shield is covered with low emissivity rhodium, the projected specific mass of the cell is 23.4 g/We. The BASE brazes and the evaporator temperatures were below the recommended limits of 1123 K and 1023 K, respectively. In addition, the temperature margin in the cell was at least + 20 K. When electrodes characterized by B=120 A.K1/2/m2.Pa and G=10 were used, the cell power increased to 8.38 We at 3.5 V and efficiency of 18.8%, for a cell specific mass of 19.7 g/We. Issues related to structure strength of the cell and the performance degradation of the BASE and electrodes are not addressed in this paper. .

Metal based gas diffusion layers for enhanced fuel cell performance at high current densities

NASA Astrophysics Data System (ADS)

Hussain, Nabeel; Van Steen, Eric; Tanaka, Shiro; Levecque, Pieter

2017-01-01

The gas diffusion layer strongly influences the performance and durability of polymer electrolyte fuel cells. A major drawback of current carbon fiber based GDLs is the non-controlled variation in porosity resulting in a random micro-structure. Moreover, when subjected to compression these materials show significant reduction in porosity and permeability leading to water management problems and mass transfer losses within the fuel cell. This study investigated the use of uniform perforated metal sheets as GDLs in conjunction with microchannel flowfields. A metal sheet design with a pitch of 110 μm and a hole diameter of 60 μm in combination with an MPL showed superior performance in the high current density region compared to a commercially available carbon paper based GDL in a single cell environment. Fuel cell testing with different oxidants (air, heliox and oxygen) indicate that the metal sheet offers both superior diffusion and reduced flooding in comparison to the carbon based GDL. The presence of the MPL has been found to be critical to the functionality of the metal sheet suggesting that the MPL design may represent an important optimisation parameter for further improvements in performance.

Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Haifang; Li, Xiaojun; Edil, Tuncer

The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empiricalmore » pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.« less

Clinically viable magnetic poly(lactide-co-glycolide) (PLGA) particles for MRI-based cell tracking

PubMed Central

Granot, Dorit; Nkansah, Michael K.; Bennewitz, Margaret F.; Tang, Kevin S.; Markakis, Eleni A.; Shapiro, Erik M.

2013-01-01

Purpose To design, fabricate, characterize and in vivo assay clinically viable magnetic particles for MRI-based cell tracking. Methods PLGA encapsulated magnetic nano- and microparticles were fabricated. Multiple biologically relevant experiments were performed to assess cell viability, cellular performance and stem cell differentiation. In vivo MRI experiments were performed to separately test cell transplantation and cell migration paradigms, as well as in vivo biodegradation. Results Highly magnetic nano- (~100 nm) and microparticles (~1–2 μm) were fabricated. Magnetic cell labeling in culture occurred rapidly achieving 3–50 pg Fe/cell at 3 hrs for different particles types, and >100 pg Fe/cell after 10 hours, without the requirement of a transfection agent, and with no effect on cell viability. The capability of magnetically labeled mesenchymal or neural stem cells to differentiate down multiple lineages, or for magnetically labeled immune cells to release cytokines following stimulation, was uncompromised. An in vivo biodegradation study revealed that NPs degraded ~80% over the course of 12 weeks. MRI detected as few as 10 magnetically labeled cells, transplanted into the brains of rats. Also, these particles enabled the in vivo monitoring of endogenous neural progenitor cell migration in rat brains over 2 weeks. Conclusion The robust MRI properties and benign safety profile of these particles make them promising candidates for clinical translation for MRI-based cell tracking. PMID:23568825

GaSb thermophotovoltaic cells grown on GaAs by molecular beam epitaxy using interfacial misfit arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, Bor-Chau, E-mail: bcjuang@ucla.edu; Laghumavarapu, Ramesh B.; Foggo, Brandon J.

There exists a long-term need for foreign substrates on which to grow GaSb-based optoelectronic devices. We address this need by using interfacial misfit arrays to grow GaSb-based thermophotovoltaic cells directly on GaAs (001) substrates and demonstrate promising performance. We compare these cells to control devices grown on GaSb substrates to assess device properties and material quality. The room temperature dark current densities show similar characteristics for both cells on GaAs and on GaSb. Under solar simulation the cells on GaAs exhibit an open-circuit voltage of 0.121 V and a short-circuit current density of 15.5 mA/cm{sup 2}. In addition, the cells on GaAsmore » substrates maintain 10% difference in spectral response to those of the control cells over a large range of wavelengths. While the cells on GaSb substrates in general offer better performance than the cells on GaAs substrates, the cost-savings and scalability offered by GaAs substrates could potentially outweigh the reduction in performance. By further optimizing GaSb buffer growth on GaAs substrates, Sb-based compound semiconductors grown on GaAs substrates with similar performance to devices grown directly on GaSb substrates could be realized.« less

Solvent-Assisted Preparation of High-Performance Mesoporous CH₃NH₃Pbl₃ Perovskite Solar Cells.

PubMed

Li, Zhi-Hua; Liu, Jie; Ma, Jing-Yuan; Jiang, Yan; Ge, Qian-Qing; Ding, Jie; Hu, Jin-Song; Wan, Li-Jun

2016-01-01

Organometal trihalide perovskite based solar cells have attracted great attention worldwide since their power conversion efficiency (PCE) have risen to over 15% within only 3 years of development. Comparing with other types of perovskite solar cells, mesostructured perovskite solar cells based on CH₃NH₃Pbl₃ as light harvesting material have already demonstrated remarkable advance in performance and reproducibility. Here, we reported a mesoscopic TiO₂/CH₃NH₃Pbl₃ heterojunction solar cell with uniform perovskite thin film prepared via solvent-assisted solution processing method. The best performing device delivered photocurrent density of 20.11 mA cm⁻², open-circuit voltage of 1.02 V, and fill factor of 0.70, leading to a PCE of 14.41%. A small anomalous hysteresis in the J-V curves was observed, where the PCE at forward scan was measured to be 84% of the PCE at reverse scan. Based on a statistical analysis, the perovskite solar cells prepared by the reported method exhibited reproducible and high PCE, indicating its promising application in the fabrication of low-cost and high-efficiency perovskite solar cells.

Item Selection for the Development of Parallel Forms from an IRT-Based Seed Test Using a Sampling and Classification Approach

ERIC Educational Resources Information Center

Chen, Pei-Hua; Chang, Hua-Hua; Wu, Haiyan

2012-01-01

Two sampling-and-classification-based procedures were developed for automated test assembly: the Cell Only and the Cell and Cube methods. A simulation study based on a 540-item bank was conducted to compare the performance of the procedures with the performance of a mixed-integer programming (MIP) method for assembling multiple parallel test…

Silicon solar cell development and radiation effects study for low temperature and low illumination intensity operation, volume 2

NASA Technical Reports Server (NTRS)

Kirkpatrick, A. R.

1972-01-01

The results are presented of a study to determine the effect of in-situ proton irradiation upon low temperature, low intensity performance of several cell types. The cell types were selected in an attempt to distinguish variations in temperature-dependent radiation resistance which could be attributed to the n-p or p-n structure, diffused or implanted junctions, crucible grown or float-zone type base material, and high or low base resistivity. The results indicate that while expected variations of performance occur at room temperature, all cell types degrade more or less similarly at lower temperatures with normalized degradation becoming increasingly rapid as temperature is reduced. Recommendations for an optimized cell for Jupiter probe use are included along with a definition of the testing required on these cells to insure good performance characteristics.

Performances of some low-cost counter electrode materials in CdS and CdSe quantum dot-sensitized solar cells.

PubMed

Jun, Hieng Kiat; Careem, Mohamed Abdul; Arof, Abdul Kariem

2014-02-10

Different counter electrode (CE) materials based on carbon and Cu2S were prepared for the application in CdS and CdSe quantum dot-sensitized solar cells (QDSSCs). The CEs were prepared using low-cost and facile methods. Platinum was used as the reference CE material to compare the performances of the other materials. While carbon-based materials produced the best solar cell performance in CdS QDSSCs, platinum and Cu2S were superior in CdSe QDSSCs. Different CE materials have different performance in the two types of QDSSCs employed due to the different type of sensitizers and composition of polysulfide electrolytes used. The poor performance of QDSSCs with some CE materials is largely due to the lower photocurrent density and open-circuit voltage. The electrochemical impedance spectroscopy performed on the cells showed that the poor-performing QDSSCs had higher charge-transfer resistances and CPE values at their CE/electrolyte interfaces.

Electrochemical Performance of Glucose/Oxygen Biofuel Cells Based on Carbon Nanostructures.

PubMed

Koo, Min-Hye; Das, Gautam; Yoon, Hyon Hee

2016-03-01

The electrochemical performance of glucose/oxygen biofuel cells based on carbon nanostructures was investigated in the present study. Different types of carbon nanomaterials, including multi-walled carbon nanotubes (MWCNT), functionalized MWCNT (f-MWCNT), carbon nanofibers (CNF), and functionalized CNF (f-CNF) were examined for electrode fabrications. The anode for glucose/oxygen biofuel cells were prepared by sequential coating of carbon nanomaterials, charge transfer complex (CTC), glucose oxidase (GOx) and nafion membrane. The anode was then integrated with a bilirubin oxidase-immobilized cathode for the biofuel cell test. It was found that the electrochemical performance of the enzyme electrodes was remarkably enhanced by the amalgamation of carbon nanomaterials with the CTC. The biofuel cell with anode comprising of f-CNF and the cathode with MWCNT exhibited the best electrochemical performance with a maximum power density of 210 μW/cm2 at a cell voltage of 0.44 V for 20 mM glucose concentration, which is comparable with the best power density value reported earlier.

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

DOEpatents

Gering, Kevin L

2013-08-27

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

Parasitic heat loss reduction in AMTEC cells by heat shield optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borkowski, C.A.; Svedberg, R.C.; Hendricks, T.J.

1997-12-31

Alkali metal thermal to electric conversion (AMTEC) cell performance can be increased by the proper design of thermal radiative shielding internal to the AMTEC cell. These heat shields essentially lower the radiative heat transfer between the heat input zone of the cell and the heat rejection zone of the cell. In addition to lowering the radiative heat transfer between the heat input and heat rejection surfaces of the cell, the shields raise the AMTEC cell performance by increasing the temperature of the beta alumina solid electrolyte (BASE). This increase in temperature of the BASE tube allows the evaporator temperature tomore » be increased without sodium condensing within the BASE tubes. Experimental testing and theoretical analysis have been performed to compare the relative merits of two candidate heat shield packages: (1) chevron, and (2) cylindrical heat shields. These two heat shield packages were compared to each other and a baseline cell which had no heat shields installed. For the two heat shield packages, the reduction in total heat transfer is between 17--27% for the heat input surface temperature varying from 700 C, 750 C, and 800 C with the heat rejection surface temperature kept at 300 C.« less

Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells

NASA Technical Reports Server (NTRS)

Hopkins, R. H.; Davis, J. R.; Blais, P. D.; Rohatgi, A.; Campbell, R. B.; Rai-Choudhury, P.; Mollenkopf, H. C.; Mccormick, J. R.

1979-01-01

The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4).

Development of an upconverting chelate assay

NASA Astrophysics Data System (ADS)

Xiao, Xudong; Haushalter, Jeanne P.; Kotz, Kenneth T.; Faris, Gregory W.

2005-04-01

We report progress on performing a cell-based assay for the detection of EGFR on cell surfaces by using upconverting chelates. An upconversion microscope has been developed for performing assays and testing optical response. A431 cells are labeled with europium DOTA and imaged using this upconverting microscope.

High Performance Tandem Perovskite/Polymer Solar Cells

NASA Astrophysics Data System (ADS)

Liu, Yao; Bag, Monojit; Page, Zachariah; Renna, Lawrence; Kim, Paul; Choi, Jaewon; Emrick, Todd; Venkataraman, D.; Russell, Thomas

Combining perovskites with other inorganic materials, such as copper indium gallium diselenide (CIGS) or silicon, is enabling significant improvement in solar cell device performance. Here, we demonstrate a highly efficient hybrid tandem solar cell fabricated through a facile solution deposition approach to give a perovskite front sub-cell and a polymer:fullerene blend back sub-cell. This methodology eliminates the adverse effects of thermal annealing during perovskite fabrication on polymer solar cells. The record tandem solar cell efficiency of 15.96% is 40% greater than the corresponding perovskite-based single junction device and 65% greater than the polymer-based single junction device, while mitigating deleterious hysteresis effects often associated with perovskite solar cells. The hybrid tandem devices demonstrate the synergistic effects arising from the combination of perovskite and polymer-based materials for solar cells. This work was supported by the Department of Energy-supported Energy Frontier Research Center at the University of Massachusetts (DE-SC0001087). The authors acknowledge the W.M. Keck Electron Microscopy.

Radiation damage in lithium-counterdoped n/p silicon solar cells

NASA Technical Reports Server (NTRS)

Hermann, A. M.; Swartz, C. K.; Brandhorst, H. W., Jr.; Weinberg, I.

1980-01-01

Lithium counterdoped n+/p silicon solar cells were irradiated with 1 MV electrons and their post irradiation performance and low temperature annealing properties were compared to that of the 0.35 ohm cm control cells. Cells fabricated from float zone and Czochralski grown silicon were investigated. It was found that the float zone cells exhibited superior radiation resistance compared to the control cells, while no improvement was noted for the Czochralski grown cells. Room temperature and 60 C annealing studies were conducted. The annealing was found to be a combination of first and second order kinetics for short times. It was suggested that the principal annealing mechanism was migration of lithium to a radiation induced defect with subsequent neutralization of the defect by combination with lithium. The effects of base lithium gradient were investigated. It was found that cells with negative base lithium gradients exhibited poor radiation resistance and performance compared to those with positive or no lithium gradients; the latter being preferred for overall performance and radiation resistance.

From coin cells to 400 mAh pouch cells: Enhancing performance of high-capacity lithium-ion cells via modifications in electrode constitution and fabrication

NASA Astrophysics Data System (ADS)

Trask, Stephen E.; Li, Yan; Kubal, Joseph J.; Bettge, Martin; Polzin, Bryant J.; Zhu, Ye; Jansen, Andrew N.; Abraham, Daniel P.

2014-08-01

In this article we describe efforts to improve performance and cycle life of cells containing Li1.2Ni0.15Mn0.55Co0.1O2-based positive and graphite-based negative electrodes. Initial work to identify high-performing materials, compositions, fabrication variables, and cycling conditions is conducted in coin cells. The resulting information is then used for the preparation of double-sided electrodes, assembly of pouch cells, and electrochemical testing. We report the cycling performance of cells with electrodes prepared under various conditions. Our data indicate that cells with positive electrodes containing 92 wt.% Li1.2Ni0.15Mn0.55Co0.1O2, 4 wt.% carbons (no graphite), and 4 wt.% PVdF (92-4-4) show ∼20% capacity fade after 1000 cycles in the 2.5-4.4 V range, significantly better than our baseline cells that show the same fade after only 450 cycles. Our analyses indicate that the major contributors to cell energy fade are capacity loss and impedance rise. Therefore incorporating approaches that minimize capacity fade and impedance rise, such as electrode coatings and electrolyte additives, can significantly enhance calendar and cycle life of this promising cell chemistry.

From coin cells to 400 mAh pouch cells: Enhancing performance of high-capacity lithium-ion cells via modifications in electrode constitution and fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trask, Stephen E.; Li, Yan; Kubal, Joseph J.

2014-08-01

In this article we describe efforts to improve performance and cycle life of cells containing Li1.2Ni0.15Mn0.55Co0.1O2-based positive and graphite-based negative electrodes. Initial work to identify high-performing materials, compositions, fabrication variables, and cycling conditions is conducted in coin cells. The resulting information is then used for the preparation of double-sided electrodes, assembly of pouch cells, and electrochemical testing. We report the cycling performance of cells with electrodes prepared under various conditions. Our data indicate that cells with positive electrodes containing 92 wt% Li1.2Ni0.15Mn0.55Co0.1O2, 4 wt% carbons (no graphite), and 4 wt% PVdF (92-4-4) show ~20% capacity fade after 1000 cycles inmore » the 2.5-4.4V range, significantly better than our baseline cells that show the same fade after only 450 cycles. Our analyses indicate that the major contributors to cell energy fade are capacity loss and impedance rise. Therefore incorporating approaches that minimize capacity fade and impedance rise, such as electrode coatings and electrolyte additives, can significantly enhance calendar and cycle life of this promising cell chemistry.« less

Lithium Batteries and Supercapacitors Capable of Operating at Low Temperatures for Planetary Exploration

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; West, W. C.; Brandon, E. J.

2012-01-01

Demonstrated improved performance with wide operating temperature electrolytes containing ester co - solvents (i.e., methyl propionate and ethyl butyrate) in a number of prototype cells: center dot Successfully scaled up low temperature technology to 12 Ah size prismatic Li - ion cells (Quallion, LCC), and demonstrated good performance down to - 60 o C. center dot Demonstrated wide operating temperature range performance ( - 60 o to +60 o C) in A123 Systems LiFePO 4 - based lithium - ion cells containing methyl butyrate - based low temperature electrolytes. These systems were also demonstrated to have excellent cycle life performance at ambient temperatures, as well as the ability to be cycled up to high temperatures.

Small stack performance of intermediate temperature-operating solid oxide fuel cells using stainless steel interconnects and anode-supported single cell

NASA Astrophysics Data System (ADS)

Bae, Joongmyeon; Lim, Sungkwang; Jee, Hyunjin; Kim, Jung Hyun; Yoo, Young-Sung; Lee, Taehee

We are developing 1 kW class solid oxide fuel cell (SOFC) system for residential power generation (RPG) application supported by Korean Government. Anode-supported single cells with thin electrolyte layer of YSZ (yttria-stabilized zirconia) or ScSZ (scandia-stabilized zirconia) for intermediate temperature operation (650-750 °C), respectively, were fabricated and small stacks were built and evaluated. The LSCF/ScSZ/Ni-YSZ single cell showed performance of 543 mW cm -2 at 650 °C and 1680 mW cm -2 at 750 °C. The voltage of 15-cell stack based on 5 cm × 5 cm single cell (LSM/YSZ/Ni-YSZ) at 150 mW was 12.5 V in hydrogen as fuel of 120 sccm per cell at 750 °C and decreased to about 10.9 V at 500 h operation time. A 5-cell stack based on the LSCF/YSZ/FL/Ni-YSZ showed the maximum power density of 30 W, 25 W and 20 W at 750 °C, 700 °C and 650 °C, respectively. LSCF/ScSZ/Ni-YSZ-based stack showed better performance than LSCF/YSZ/Ni-YSZ stack from the experiment temperature range. I- V characteristics by using hydrogen gas and reformate gas of methane as fuel were investigated at 750 °C in LSCF/ScSZ/FL/Ni-YSZ-based 5-cell stack.

Texting while driving: is speech-based text entry less risky than handheld text entry?

PubMed

He, J; Chaparro, A; Nguyen, B; Burge, R J; Crandall, J; Chaparro, B; Ni, R; Cao, S

2014-11-01

Research indicates that using a cell phone to talk or text while maneuvering a vehicle impairs driving performance. However, few published studies directly compare the distracting effects of texting using a hands-free (i.e., speech-based interface) versus handheld cell phone, which is an important issue for legislation, automotive interface design and driving safety training. This study compared the effect of speech-based versus handheld text entries on simulated driving performance by asking participants to perform a car following task while controlling the duration of a secondary text-entry task. Results showed that both speech-based and handheld text entries impaired driving performance relative to the drive-only condition by causing more variation in speed and lane position. Handheld text entry also increased the brake response time and increased variation in headway distance. Text entry using a speech-based cell phone was less detrimental to driving performance than handheld text entry. Nevertheless, the speech-based text entry task still significantly impaired driving compared to the drive-only condition. These results suggest that speech-based text entry disrupts driving, but reduces the level of performance interference compared to text entry with a handheld device. In addition, the difference in the distraction effect caused by speech-based and handheld text entry is not simply due to the difference in task duration. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

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

Optoelectrical modeling of solar cells based on c-Si/a-Si:H nanowire array: focus on the electrical transport in between the nanowires

NASA Astrophysics Data System (ADS)

Levtchenko, Alexandra; Le Gall, Sylvain; Lachaume, Raphaël; Michallon, Jérôme; Collin, Stéphane; Alvarez, José; Djebbour, Zakaria; Kleider, Jean-Paul

2018-06-01

By coupling optical and electrical modeling, we have investigated the photovoltaic performances of p-i-n radial nanowires array based on crystalline p-type silicon (c-Si) core/hydrogenated amorphous silicon (a-Si:H) shell. By varying either the doping concentration of the c-Si core, or back contact work function we can separate and highlight the contribution to the cell’s performance of the nanowires themselves (the radial cell) from the interspace between the nanowires (the planar cell). We show that the build-in potential (V bi) in the radial and planar cells strongly depends on the doping of c-Si core and the work function of the back contact respectively. Consequently, the solar cell’s performance is degraded if either the doping concentration of the c-Si core, or/and the work function of the back contact is too low. By inserting a thin (p) a-Si:H layer between both core/absorber and back contact/absorber, the performance of the solar cell can be improved by partly fixing the V bi at both interfaces due to strong electrostatic screening effect. Depositing such a buffer layer playing the role of an electrostatic screen for charge carriers is a suggested way of enhancing the performance of solar cells based on radial p-i-n or n-i-p nanowire array.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

PubMed

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-18

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

NASA Astrophysics Data System (ADS)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-01

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

The Sodium Exposure Test Cell to determine operating parameters for AMTEC electrochemical cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryan, M.A.; Williams, R.M.; Lara, L.

1998-07-01

The Sodium Exposure Test Cell (SETC) is a non-power producing cell which has been developed to evaluate and test components of the electrochemical cell in an Alkali Metal Thermal to Electric Converter. Performance and time dependence of performance of the electrode and the electrolyte in AMTEC cells can be tested in an SETC, and performance parameters which correlate with those taken from AMTEC operation can be calculated from data taken in an SETC. The components of the AMTEC electrochemical cell which are evaluated in an SETC are the electrode, {beta}{double{underscore}prime}-alumina solid electrolyte (BASE), the current collection network, and the containment.more » The components are held in low pressure sodium vapor at a temperature which reflects their operating conditions in an AMTEC device, and operating parameters determined. Electrodes and BASE are evaluated by measuring current-voltage (IV) characteristics and using Electrochemical Impedance Spectroscopy (EIS). Using these techniques, electrode performance parameters such as the exchange current (B), the morphology factor (G), and contact resistance between electrode and current collection network can be determined. The ionic conductivity (s) of BASE can also be determined. IV curves and EIS measurements are made at intervals over periods of several hundreds of hours in order to evaluate degradation of AMTEC electrochemical cell components. Electrode and BASE are analyzed after an SETC experiment using Scanning Electron Microscopy, Electron Dispersive Spectroscopy, and X-Ray Diffraction. These techniques allow evaluation of interaction of materials and changes in the composition and structure of materials. The purpose of these experiments is determination of the changes of operating parameters as a function of time in order to predict the operating lifetime of AMTEC cells.« less

Improved Low Temperature Performance of Supercapacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J.; West, William C.; Smart, Marshall C.; Gnanaraj, Joe

2013-01-01

Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

Systems, methods and computer-readable media to model kinetic performance of rechargeable electrochemical devices

DOEpatents

Gering, Kevin L.

2013-01-01

A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics. The computing system also analyzes the cell information of the electrochemical cell with a Butler-Volmer (BV) expression modified to determine exchange current density of the electrochemical cell by including kinetic performance information related to pulse-time dependence, electrode surface availability, or a combination thereof. A set of sigmoid-based expressions may be included with the modified-BV expression to determine kinetic performance as a function of pulse time. The determined exchange current density may be used with the modified-BV expression, with or without the sigmoid expressions, to analyze other characteristics of the electrochemical cell. Model parameters can be defined in terms of cell aging, making the overall kinetics model amenable to predictive estimates of cell kinetic performance along the aging timeline.

Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

2012-01-01

Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

Performance parameters of TiN electrodes for AMTEC cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryan, Margaret A.; Williams, Roger M.; Homer, Margie L.

1999-01-22

In order to model the lifetime of the electrochemical cell in an Alkali Metal Thermal to Electric Converter (AMTEC), studies of TiN electrodes on beta'-alumina solid electrolytes (BASE) have been made to determine the performance parameters over time. Performance parameters include, G, the morphology factor, and B, the temperature independent exchange current. The results of several experiments, both AMTEC cells and Sodium Exposure Test Cells, in which TiN electrodes have been studied at 1120-1200 K are described here.

Balancing Particle and Mesh Computation in a Particle-In-Cell Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worley, Patrick H; D'Azevedo, Eduardo; Hager, Robert

2016-01-01

The XGC1 plasma microturbulence particle-in-cell simulation code has both particle-based and mesh-based computational kernels that dominate performance. Both of these are subject to load imbalances that can degrade performance and that evolve during a simulation. Each separately can be addressed adequately, but optimizing just for one can introduce significant load imbalances in the other, degrading overall performance. A technique has been developed based on Golden Section Search that minimizes wallclock time given prior information on wallclock time, and on current particle distribution and mesh cost per cell, and also adapts to evolution in load imbalance in both particle and meshmore » work. In problems of interest this doubled the performance on full system runs on the XK7 at the Oak Ridge Leadership Computing Facility compared to load balancing only one of the kernels.« less

Efficient Lead-Free Solar Cells Based on Hollow {en}MASnI3 Perovskites.

PubMed

Ke, Weijun; Stoumpos, Constantinos C; Spanopoulos, Ioannis; Mao, Lingling; Chen, Michelle; Wasielewski, Michael R; Kanatzidis, Mercouri G

2017-10-18

Tin-based perovskites have very comparable electronic properties to lead-based perovskites and are regarded as possible lower toxicity alternates for solar cell applications. However, the efficiency of tin-based perovskite solar cells is still low and they exhibit poor air stability. Here, we report lead-free tin-based solar cells with greatly enhanced performance and stability using so-called "hollow" ethylenediammonium and methylammonium tin iodide ({en}MASnI 3 ) perovskite as absorbers. Our results show that en can improve the film morphology and most importantly can serve as a new cation to be incorporated into the 3D MASnI 3 lattice. When the cation of en becomes part of the 3D structure, a high density of SnI 2 vacancies is created resulting in larger band gap, larger unit cell volume, lower trap-state density, and much longer carrier lifetime compared to classical MASnI 3 . The best-performing {en}MASnI 3 solar cell has achieved a high efficiency of 6.63% with an open circuit voltage of 428.67 mV, a short-circuit current density of 24.28 mA cm -2 , and a fill factor of 63.72%. Moreover, the {en}MASnI 3 device shows much better air stability than the neat MASnI 3 device. Comparable performance is also achieved for cesium tin iodide solar cells with en loading, demonstrating the broad scope of this approach.

Solid Polymer Electrolyte (SPE) fuel cell technology program

NASA Technical Reports Server (NTRS)

1978-01-01

Many previously demonstrated improved fuel cell features were consolidated to (1) obtain a better understanding of the observed characteristics of the operating laboratory-sized cells; (2) evaluate appropriate improved fuel cell features in 0.7 sq ft cell hardware; and (3) study the resultant fuel cell capability and determine its impact on various potential fuel cell space missions. The observed performance characteristics of the fuel cell at high temperatures and high current densities were matched with a theoretical model based on the change in Gibbs free energy voltage with respect to temperature and internal resistance change with current density. Excellent agreement between the observed and model performance was obtained. The observed performance decay with operational time on cells with very low noble metal loadings (0.05 mg/sq cm) were shown to be related to loss in surface area. Cells with the baseline amount of noble catalyst electrode loading demonstrated over 40,000 hours of stable performance.

Yttria-stabilized zirconia solid oxide electrolyte fuel cells: Monolithic solid oxide fuel cells

NASA Astrophysics Data System (ADS)

1990-10-01

The monolithic solid oxide fuel cell (MSOFC) is currently under development for a variety of applications including coal-based power generation. The MSOFC is a design concept that places the thin components of a solid oxide fuel cell in lightweight, compact, corrugated structure, and so achieves high efficiency and excellent performance simultaneously with high power density. The MSOFC can be integrated with coal gasification plants and is expected to have high overall efficiency in the conversion of the chemical energy of coal to electrical energy. This report describes work aimed at: (1) assessing manufacturing costs for the MSOFC and system costs for a coal-based plant; (2) modifying electrodes and electrode/electrolyte interfaces to improve the electrochemical performance of the MSOFC; and (3) testing the performance of the MSOFC on hydrogen and simulated coal gas. Manufacturing costs for both the coflow and crossflow MSOFC's were assessed based on the fabrication flow charts developed by direct scaleup of tape calendering and other laboratory processes. Integrated coal-based MSOFC systems were investigated to determine capital costs and costs of electricity. Design criteria were established for a coal-fueled 200-Mw power plant. Four plant arrangements were evaluated, and plant performance was analyzed. Interfacial modification involved modification of electrodes and electrode/electrolyte interfaces to improve the MSOFC electrochemical performance. Work in the cathode and cathode/electrolyte interface was concentrated on modification of electrode porosity, electrode morphology, electrode material, and interfacial bonding. Modifications of the anode and anode/electrolyte interface included the use of additives and improvement of nickel distribution. Single cells have been tested for their electrochemical performance. Performance data were typically obtained with humidified H2 or simulated coal gas and air or oxygen.

Fabrication and performance analysis of 4-sq cm indium tin oxide/InP photovoltaic solar cells

NASA Technical Reports Server (NTRS)

Gessert, T. A.; Li, X.; Phelps, P. W.; Coutts, T. J.; Tzafaras, N.

1991-01-01

Large-area photovoltaic solar cells based on direct current magnetron sputter deposition of indium tin oxide (ITO) into single-crystal p-InP substrates demonstrated both the radiation hardness and high performance necessary for extraterrestrial applications. A small-scale production project was initiated in which approximately 50 ITO/InP cells are being produced. The procedures used in this small-scale production of 4-sq cm ITO/InP cells are presented and discussed. The discussion includes analyses of performance range of all available production cells, and device performance data of the best cells thus far produced. Additionally, processing experience gained from the production of these cells is discussed, indicating other issues that may be encountered when large-scale productions are begun.

Nanostructure-based proton exchange membrane for fuel cell applications at high temperature.

PubMed

Li, Junsheng; Wang, Zhengbang; Li, Junrui; Pan, Mu; Tang, Haolin

2014-02-01

As a clean and highly efficient energy source, the proton exchange membrane fuel cell (PEMFC) has been considered an ideal alternative to traditional fossil energy sources. Great efforts have been devoted to realizing the commercialization of the PEMFC in the past decade. To eliminate some technical problems that are associated with the low-temperature operation (such as catalyst poisoning and poor water management), PEMFCs are usually operated at elevated temperatures (e.g., > 100 degrees C). However, traditional proton exchange membrane (PEM) shows poor performance at elevated temperature. To achieve a high-performance PEM for high temperature fuel cell applications, novel PEMs, which are based on nanostructures, have been developed recently. In this review, we discuss and summarize the methods for fabricating the nanostructure-based PEMs for PEMFC operated at elevated temperatures and the high temperature performance of these PEMs. We also give an outlook on the rational design and development of the nanostructure-based PEMs.

Development & experimental validation of a SINDA/FLUINT thermal/fluid/electrical model of a multi-tube AMTEC cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendricks, T.J.; Borkowski, C.A.; Huang, C.

1998-01-01

AMTEC (Alkali Metal Thermal-to-Electric Conversion) cell development has received increased attention and funding in the space power community because of several desirable performance characteristics compared to current radioisotope thermoelectric generation and solar photovoltaic (PV) power generation. AMTEC cell development is critically dependent upon the ability to predict thermal, fluid dynamic and electrical performance of an AMTEC cell which has many complex thermal, fluid dynamic and electrical processes and interactions occurring simultaneously. Development of predictive capability is critical to understanding the complex processes and interactions within the AMTEC cell, and thereby creating the ability to design high-performance, cost-effective AMTEC cells. Amore » flexible, sophisticated thermal/fluid/electrical model of an operating AMTEC cell has been developed using the SINDA/FLUINT analysis software. This model can accurately simulate AMTEC cell performance at any hot side and cold side temperature combination desired, for any voltage and current conditions, and for a broad range of cell design parameters involving the cell dimensions, current collector and electrode design, electrode performance parameters, and cell wall and thermal shield emissivity. The model simulates the thermal radiation network within the AMTEC cell using RadCAD thermal radiation analysis; hot side, cold side and cell wall conductive and radiative coupling; BASE (Beta Alumina Solid Electrode) tube electrochemistry, including electrode over-potentials; the fluid dynamics of the low-pressure sodium vapor flow to the condenser and liquid sodium flow in the wick; sodium condensation at the condenser; and high-temperature sodium evaporation in the wick. The model predicts the temperature profiles within the AMTEC cell walls, the BASE tube temperature profiles, the sodium temperature profile in the artery return, temperature profiles in the evaporator, thermal energy flows throughout the AMTEC cell, all sodium pressure drops from hot BASE tubes to the condenser, the current, voltage, and power output from the cell, and the cell efficiency. This AMTEC cell model is so powerful and flexible that it is used in radioisotope AMTEC power system design, solar AMTEC power system design, and combustion-driven power system design on several projects at Advanced Modular Power Systems, Inc. (AMPS). The model has been successfully validated against actual cell experimental data and its performance predictions agree very well with experimental data on PX-5B cells and other test cells at AMPS. {copyright} {ital 1998 American Institute of Physics.}« less

Comparative Aging Study of Organic Solar Cells Utilizing Polyaniline and PEDOT:PSS as Hole Transport Layers.

PubMed

Abdulrazzaq, Omar; Bourdo, Shawn E; Woo, Myungwu; Saini, Viney; Berry, Brian C; Ghosh, Anindya; Biris, Alexandru S

2015-12-23

The aging effect on P3HT:PCBM organic solar cells was investigated with camphorsulfonic doped polyaniline (PANI:CSA) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) used as the hole transport layer (HTL). The cells were encapsulated and exposed to a continuous normal atmosphere on a dark shelf and then characterized intermittently for more than two years. The photovoltaic results revealed that the cells with PSS HTL showed better initial results than the cells with PANI:CSA HTL. Over time, PSS-based cells exhibited faster degradation than PANI:CSA-based cells, where the average efficiency of six cells dropped to zero in less than one and a half years. On the other hand, PANI:CSA-based cells exhibited a much more stable performance with an average efficiency drop of only 15% of their initial values after one and a half years and 63% after two years. A single-diode model was utilized to fit the experimental data with the theoretical curve to extract the diode parameters, such as the ideality factor, to explain the effect of aging on the diode's performance.

Effects of Impurities and Processing on Silicon Solar Cells, Phase 3

NASA Technical Reports Server (NTRS)

Hopkins, R. H.; Davis, J. R.; Blais, P. D.; Rohatgi, A.; Campbell, R. B.; Rai-Choudhury, P.; Stapleton, R. E.; Mollenkopf, H. C.; Mccormick, J. R.

1979-01-01

Results of the 14th quarterly report are presented for a program designed to assess the effects of impurities, thermochemical processes and any impurity process interactions on the performance of terrestrial silicon solar cells. The Phase 3 effort encompasses: (1) potential interactions between impurities and thermochemical processing of silicon; (2) impurity-cell performance relationships in n-base silicon; (3) effect of contaminants introduced during silicon production, refining or crystal growth on cell performance; (4) effects of nonuniform impurity distributions in large area silicon wafers; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells.

Enhanced photovoltaic performance of inverted pyramid-based nanostructured black-silicon solar cells passivated by an atomic-layer-deposited Al2O3 layer.

PubMed

Chen, Hong-Yan; Lu, Hong-Liang; Ren, Qing-Hua; Zhang, Yuan; Yang, Xiao-Feng; Ding, Shi-Jin; Zhang, David Wei

2015-10-07

Inverted pyramid-based nanostructured black-silicon (BS) solar cells with an Al2O3 passivation layer grown by atomic layer deposition (ALD) have been demonstrated. A multi-scale textured BS surface combining silicon nanowires (SiNWs) and inverted pyramids was obtained for the first time by lithography and metal catalyzed wet etching. The reflectance of the as-prepared BS surface was about 2% lower than that of the more commonly reported upright pyramid-based SiNW BS surface over the whole of the visible light spectrum, which led to a 1.7 mA cm(-2) increase in short circuit current density. Moreover, the as-prepared solar cells were further passivated by an ALD-Al2O3 layer. The effect of annealing temperature on the photovoltaic performance of the solar cells was investigated. It was found that the values of all solar cell parameters including short circuit current, open circuit voltage, and fill factor exhibit a further increase under an optimized annealing temperature. Minority carrier lifetime measurements indicate that the enhanced cell performance is due to the improved passivation quality of the Al2O3 layer after thermal annealing treatments. By combining these two refinements, the optimized SiNW BS solar cells achieved a maximum conversion efficiency enhancement of 7.6% compared to the cells with an upright pyramid-based SiNWs surface and conventional SiNx passivation.

Component Cell-Based Restriction of Spectral Conditions and the Impact on CPV Module Power Rating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, Matthew T; Steiner, Marc; Siefer, Gerald

One approach to consider the prevailing spectral conditions when performing CPV module power ratings according to the standard IEC 62670-3 is based on spectral matching ratios (SMRs) determined by the means of component cell sensors. In this work, an uncertainty analysis of the SMR approach is performed based on a dataset of spectral irradiances created with SMARTS2. Using these illumination spectra, the respective efficiencies of multijunction solar cells with different cell architectures are calculated. These efficiencies were used to analyze the influence of different component cell sensors and SMR filtering methods. The 3 main findings of this work are asmore » follows. First, component cells based on the lattice-matched triple-junction (LM3J) cell are suitable for restricting spectral conditions and are qualified for the standardized power rating of CPV modules - even if the CPV module is using multijunction cells other than LM3J. Second, a filtering of all 3 SMRs with +/-3.0% of unity results in the worst case scenario in an underestimation of -1.7% and overestimation of +2.4% compared to AM1.5d efficiency. Third, there is no benefit in matching the component cells to the module cell in respect to the measurement uncertainty.« less

Droplet-based gene expression analysis using a device with magnetic force-based-droplet-handling system.

PubMed

Okochi, Mina; Tsuchiya, Hiroyoshi; Kumazawa, Fumitaka; Shikida, Mitsuhiro; Honda, Hiroyuki

2010-02-01

A droplet-based cell lysis and reverse transcription-polymerase chain reaction (PCR) were performed on-chip employing magnetic force-based-droplet-handling system. The actuation with a magnet offers a simple system for droplet manipulation; it does not need mechanical fluidic systems such as pumps and valves for handling solutions. It can be used as a powerful tool for various biochemical applications by moving and coalescing sample droplets using magnetic beads immersed in mineral oil. The droplet containing magnetic beads and the cells were manipulated with the magnet located underneath the channel, and coalesced with a droplet of lysis buffer. Using K562 cells as the leukemia model, the cell lysis, cDNA synthesis, and amplification of WT1 gene that is known as the prognostic factor for acute leukemia were successfully performed from a single cell. Copyright (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Electric terminal performance and characterization of solid oxide fuel cells and systems

NASA Astrophysics Data System (ADS)

Lindahl, Peter Allan

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices which can effect efficient, clean, and quiet conversion of chemical to electrical energy. In contrast to conventional electricity generation systems which feature multiple discrete energy conversion processes, SOFCs are direct energy conversion devices. That is, they feature a fully integrated chemical to electrical energy conversion process where the electric load demanded of the cell intrinsically drives the electrochemical reactions and associated processes internal to the cell. As a result, the cell's electric terminals provide a path for interaction between load side electric demand and the conversion side processes. The implication of this is twofold. First, the magnitude and dynamic characteristics of the electric load demanded of the cell can directly impact the long-term efficacy of the cell's chemical to electrical energy conversion. Second, the electric terminal response to dynamic loads can be exploited for monitoring the cell's conversion side processes and used in diagnostic analysis and degradation-mitigating control schemes. This dissertation presents a multi-tier investigation into this electric terminal based performance characterization of SOFCs through the development of novel test systems, analysis techniques and control schemes. First, a reference-based simulation system is introduced. This system scales up the electric terminal performance of a prototype SOFC system, e.g. a single fuel cell, to that of a full power-level stack. This allows realistic stack/load interaction studies while maintaining explicit ability for post-test analysis of the prototype system. Next, a time-domain least squares fitting method for electrochemical impedance spectroscopy (EIS) is developed for reduced-time monitoring of the electrochemical and physicochemical mechanics of the fuel cell through its electric terminals. The utility of the reference-based simulator and the EIS technique are demonstrated through their combined use in the performance testing of a hybrid-source power management (HSPM) system designed to allow in-situ EIS monitoring of a stack under dynamic loading conditions. The results from the latter study suggest that an HSPM controller allows an opportunity for in-situ electric terminal monitoring and control-based mitigation of SOFC degradation. As such, an exploration of control-based SOFC degradation mitigation is presented and ideas for further work are suggested.

Segmentation and classification of cell cycle phases in fluorescence imaging.

PubMed

Ersoy, Ilker; Bunyak, Filiz; Chagin, Vadim; Cardoso, M Christina; Palaniappan, Kannappan

2009-01-01

Current chemical biology methods for studying spatiotemporal correlation between biochemical networks and cell cycle phase progression in live-cells typically use fluorescence-based imaging of fusion proteins. Stable cell lines expressing fluorescently tagged protein GFP-PCNA produce rich, dynamically varying sub-cellular foci patterns characterizing the cell cycle phases, including the progress during the S-phase. Variable fluorescence patterns, drastic changes in SNR, shape and position changes and abundance of touching cells require sophisticated algorithms for reliable automatic segmentation and cell cycle classification. We extend the recently proposed graph partitioning active contours (GPAC) for fluorescence-based nucleus segmentation using regional density functions and dramatically improve its efficiency, making it scalable for high content microscopy imaging. We utilize surface shape properties of GFP-PCNA intensity field to obtain descriptors of foci patterns and perform automated cell cycle phase classification, and give quantitative performance by comparing our results to manually labeled data.

Experimental demonstration of programmable multi-functional spin logic cell based on spin Hall effect

NASA Astrophysics Data System (ADS)

Zhang, X.; Wan, C. H.; Yuan, Z. H.; Fang, C.; Kong, W. J.; Wu, H.; Zhang, Q. T.; Tao, B. S.; Han, X. F.

2017-04-01

Confronting with the gigantic volume of data produced every day, raising integration density by reducing the size of devices becomes harder and harder to meet the ever-increasing demand for high-performance computers. One feasible path is to actualize more logic functions in one cell. In this respect, we experimentally demonstrate a prototype spin-orbit torque based spin logic cell integrated with five frequently used logic functions (AND, OR, NOT, NAND and NOR). The cell can be easily programmed and reprogrammed to perform desired function. Furthermore, the information stored in cells is symmetry-protected, making it possible to expand into logic gate array where the cell can be manipulated one by one without changing the information of other undesired cells. This work provides a prospective example of multi-functional spin logic cell with reprogrammability and nonvolatility, which will advance the application of spin logic devices.

Fabrication of nanostructured CIGS solar cells

NASA Astrophysics Data System (ADS)

Zhang, Hongwang; Wang, Fang; Parry, James; Perera, Samanthe; Zeng, Hao

2012-02-01

We present the work on Cu(In,Ga)(Se,S)2 based nanostructured solar cells based on nanowire arrays. CIGS as the light absorber for thin-film solar cells has been widely studied recently, due to its high absorption coefficient, long-term stability, and low-cost of fabrication. Recently, solution phase processed CIGS thin film solar cells attracted great attention due to their extremely low fabrication cost. However, the performance is lower than vacuum based thin films possibly due to higher density of defects and lower carrier mobility. On the other hand, one dimensional ordered nanostructures such as nanowires and nanorods can be used to make redial junction solar cells, where the orthogonality between light absorption and charge carrier separation can lead to enhanced PV performance. Since the charge carriers only need to traverse a short distance in the radial direction before they are separated at the heterojunction interface, the radial junction scheme can be more defect tolerant than their planar junction scheme. In this work, a wide band gap nanowire or nanotube array such as TiO2 is used as a scaffold where CIGS is conformally coated using solution phase to obtain a radial heterojunction solar cell. Their performance is compared that of the planar thin film solar cells fabricated with the same materials.

Monte Carlo dose calculation using a cell processor based PlayStation 3 system

NASA Astrophysics Data System (ADS)

Chow, James C. L.; Lam, Phil; Jaffray, David A.

2012-02-01

This study investigates the performance of the EGSnrc computer code coupled with a Cell-based hardware in Monte Carlo simulation of radiation dose in radiotherapy. Performance evaluations of two processor-intensive functions namely, HOWNEAR and RANMAR_GET in the EGSnrc code were carried out basing on the 20-80 rule (Pareto principle). The execution speeds of the two functions were measured by the profiler gprof specifying the number of executions and total time spent on the functions. A testing architecture designed for Cell processor was implemented in the evaluation using a PlayStation3 (PS3) system. The evaluation results show that the algorithms examined are readily parallelizable on the Cell platform, provided that an architectural change of the EGSnrc was made. However, as the EGSnrc performance was limited by the PowerPC Processing Element in the PS3, PC coupled with graphics processing units or GPCPU may provide a more viable avenue for acceleration.

Analytical Study on Multi-Tier 5G Heterogeneous Small Cell Networks: Coverage Performance and Energy Efficiency.

PubMed

Xiao, Zhu; Liu, Hongjing; Havyarimana, Vincent; Li, Tong; Wang, Dong

2016-11-04

In this paper, we investigate the coverage performance and energy efficiency of multi-tier heterogeneous cellular networks (HetNets) which are composed of macrocells and different types of small cells, i.e., picocells and femtocells. By virtue of stochastic geometry tools, we model the multi-tier HetNets based on a Poisson point process (PPP) and analyze the Signal to Interference Ratio (SIR) via studying the cumulative interference from pico-tier and femto-tier. We then derive the analytical expressions of coverage probabilities in order to evaluate coverage performance in different tiers and investigate how it varies with the small cells' deployment density. By taking the fairness and user experience into consideration, we propose a disjoint channel allocation scheme and derive the system channel throughput for various tiers. Further, we formulate the energy efficiency optimization problem for multi-tier HetNets in terms of throughput performance and resource allocation fairness. To solve this problem, we devise a linear programming based approach to obtain the available area of the feasible solutions. System-level simulations demonstrate that the small cells' deployment density has a significant effect on the coverage performance and energy efficiency. Simulation results also reveal that there exits an optimal small cell base station (SBS) density ratio between pico-tier and femto-tier which can be applied to maximize the energy efficiency and at the same time enhance the system performance. Our findings provide guidance for the design of multi-tier HetNets for improving the coverage performance as well as the energy efficiency.

Density-based clustering analyses to identify heterogeneous cellular sub-populations

NASA Astrophysics Data System (ADS)

Heaster, Tiffany M.; Walsh, Alex J.; Landman, Bennett A.; Skala, Melissa C.

2017-02-01

Autofluorescence microscopy of NAD(P)H and FAD provides functional metabolic measurements at the single-cell level. Here, density-based clustering algorithms were applied to metabolic autofluorescence measurements to identify cell-level heterogeneity in tumor cell cultures. The performance of the density-based clustering algorithm, DENCLUE, was tested in samples with known heterogeneity (co-cultures of breast carcinoma lines). DENCLUE was found to better represent the distribution of cell clusters compared to Gaussian mixture modeling. Overall, DENCLUE is a promising approach to quantify cell-level heterogeneity, and could be used to understand single cell population dynamics in cancer progression and treatment.

Tailoring gadolinium-doped ceria-based solid oxide fuel cells to achieve 2 W cm(-2) at 550 °C.

PubMed

Lee, Jin Goo; Park, Jeong Ho; Shul, Yong Gun

2014-06-04

Low-temperature operation is necessary for next-generation solid oxide fuel cells due to the wide variety of their applications. However, significant increases in the fuel cell losses appear in the low-temperature solid oxide fuel cells, which reduce the cell performance. To overcome this problem, here we report Gd0.1Ce0.9O1.95-based low-temperature solid oxide fuel cells with nanocomposite anode functional layers, thin electrolytes and core/shell fibre-structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ-Gd0.1Ce0.9O1.95 cathodes. In particular, the report describes the use of the advanced electrospinning and Pechini process in the preparation of the core/shell-fibre-structured cathodes. The fuel cells show a very high performance of 2 W cm(-2) at 550 °C in hydrogen, and are stable for 300 h even under the high current density of 1 A cm(-2). Hence, the results suggest that stable and high-performance solid oxide fuel cells at low temperatures can be achieved by modifying the microstructures of solid oxide fuel cell components.

Comparison of the mechanobiological performance of bone tissue scaffolds based on different unit cell geometries.

PubMed

Rodríguez-Montaño, Óscar L; Cortés-Rodríguez, Carlos Julio; Uva, Antonio E; Fiorentino, Michele; Gattullo, Michele; Monno, Giuseppe; Boccaccio, Antonio

2018-07-01

Enhancing the performance of scaffolds for bone regeneration requires a multidisciplinary approach involving competences in the fields of Biology, Medicine and Engineering. A number of studies have been conducted to investigate the influence of scaffolds design parameters on their mechanical and biological response. The possibilities offered by the additive manufacturing techniques to fabricate sophisticated and very complex microgeometries that until few years ago were just a geometrical abstraction, led many researchers to design scaffolds made from different unit cell geometries. The aim of this work is to find, based on mechanobiological criteria and for different load regimes, the optimal geometrical parameters of scaffolds made from beam-based repeating unit cells, namely, truncated cuboctahedron, truncated cube, rhombic dodecahedron and diamond. The performance, -expressed in terms of percentage of the scaffold volume occupied by bone-, of the scaffolds based on these unit cells was compared with that of scaffolds based on other unit cell geometries such as: hexahedron and rhombicuboctahedron. A very intriguing behavior was predicted for the truncated cube unit cell that allows the formation of large amounts of bone for low load values and of very small amounts for the medium-high ones. For high values of load, scaffolds made from hexahedron unit cells were predicted to favor the formation of the largest amounts of bone. In a clinical context where medical solutions become more and more customized, this study offers a support to the surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhancing the Efficiency of Silicon-Based Solar Cells by the Piezo-Phototronic Effect.

PubMed

Zhu, Laipan; Wang, Longfei; Pan, Caofeng; Chen, Libo; Xue, Fei; Chen, Baodong; Yang, Leijing; Su, Li; Wang, Zhong Lin

2017-02-28

Although there are numerous approaches for fabricating solar cells, the silicon-based photovoltaics are still the most widely used in industry and around the world. A small increase in the efficiency of silicon-based solar cells has a huge economic impact and practical importance. We fabricate a silicon-based nanoheterostructure (p + -Si/p-Si/n + -Si (and n-Si)/n-ZnO nanowire (NW) array) photovoltaic device and demonstrate the enhanced device performance through significantly enhanced light absorption by NW array and effective charge carrier separation by the piezo-phototronic effect. The strain-induced piezoelectric polarization charges created at n-doped Si-ZnO interfaces can effectively modulate the corresponding band structure and electron gas trapped in the n + -Si/n-ZnO NW nanoheterostructure and thus enhance the transport process of local charge carriers. The efficiency of the solar cell was improved from 8.97% to 9.51% by simply applying a static compress strain. This study indicates that the piezo-phototronic effect can enhance the performance of a large-scale silicon-based solar cell, with great potential for industrial applications.

Encapsulating Non-Human Primate Multipotent Stromal Cells in Alginate via High Voltage for Cell-Based Therapies and Cryopreservation

PubMed Central

Gryshkov, Oleksandr; Pogozhykh, Denys; Hofmann, Nicola; Pogozhykh, Olena; Mueller, Thomas; Glasmacher, Birgit

2014-01-01

Alginate cell-based therapy requires further development focused on clinical application. To assess engraftment, risk of mutations and therapeutic benefit studies should be performed in an appropriate non-human primate model, such as the common marmoset (Callithrix jacchus). In this work we encapsulated amnion derived multipotent stromal cells (MSCs) from Callithrix jacchus in defined size alginate beads using a high voltage technique. Our results indicate that i) alginate-cell mixing procedure and cell concentration do not affect the diameter of alginate beads, ii) encapsulation of high cell numbers (up to 10×106 cells/ml) can be performed in alginate beads utilizing high voltage and iii) high voltage (15–30 kV) does not alter the viability, proliferation and differentiation capacity of MSCs post-encapsulation compared with alginate encapsulated cells produced by the traditional air-flow method. The consistent results were obtained over the period of 7 days of encapsulated MSCs culture and after cryopreservation utilizing a slow cooling procedure (1 K/min). The results of this work show that high voltage encapsulation can further be maximized to develop cell-based therapies with alginate beads in a non-human primate model towards human application. PMID:25259731

Performance of vegetative and fruits Zn/Cu based electrochemical cell

NASA Astrophysics Data System (ADS)

Khan, Md. Kamrul Alam, Prof. _., Dr.

2017-01-01

We have studied the performance of PKL, Aloe Vera, Tomato and Lemon juice electrochemical Cells without load condition for 1:1 Zn/Cu based electrodes. It was studied the variation of Open circuit voltage (Voc), Short current (Isc) and Maximum Power (Pmax) with the variation of time for PKL, Aloe Vera, Tomato and Lemon juice electrochemical Cells. It was seen from the research observation that the discharge characteristic of the PKL electrochemical cell was more efficient than the other three Aloe Vera, Tomato and Lemon juice electrochemical Cells. Because the Open circuit voltage (Voc), Short current (Isc) and Maximum Power (Pmax) are more stable and steady than the others three Aloe Vera, Tomato and Lemon juice electrochemical Cells. Furthermore, to enhance the performance we have also studied the secondary salt effect by using the NaCl as an electrolyte with the PKL, Aloe Vera and Lemon juice electrochemical Cells. Most of the results have been tabulated and graphically discussed. I am grateful to the authority of the Science and technology ministry,Bangladesh for financial support during the research work.

Considerations for Estimating Electrode Performance in Li-Ion Cells

NASA Technical Reports Server (NTRS)

Bennett, William R.

2012-01-01

Advanced electrode materials with increased specific capacity and voltage performance are critical to the development of Li-ion batteries with increased specific energy and energy density. Although performance metrics for individual electrodes are critically important, a fundamental understanding of the interactions of electrodes in a full cell is essential to achieving the desired performance, and for establishing meaningful goals for electrode performance. This paper presents practical design considerations for matching positive and negative electrodes in a viable design. Methods for predicting cell-level discharge voltage, based on laboratory data for individual electrodes, are presented and discussed.

Electrolytic hydrogen production: An analysis and review

NASA Technical Reports Server (NTRS)

Evangelista, J.; Phillips, B.; Gordon, L.

1975-01-01

The thermodynamics of water electrolysis cells is presented, followed by a review of current and future technology of commercial cells. The irreversibilities involved are analyzed and the resulting equations assembled into a computer simulation model of electrolysis cell efficiency. The model is tested by comparing predictions based on the model to actual commercial cell performance, and a parametric investigation of operating conditions is performed. Finally, the simulation model is applied to a study of electrolysis cell dynamics through consideration of an ideal pulsed electrolyzer.

Performance and stability of low-cost dye-sensitized solar cell based crude and pre-concentrated anthocyanins: Combined experimental and DFT/TDDFT study

NASA Astrophysics Data System (ADS)

Chaiamornnugool, Phrompak; Tontapha, Sarawut; Phatchana, Ratchanee; Ratchapolthavisin, Nattawat; Kanokmedhakul, Somdej; Sang-aroon, Wichien; Amornkitbamrung, Vittaya

2017-01-01

The low cost DSSCs utilized by crude and pre-concentrated anthocyanins extracted from six anthocyanin-rich samples including mangosteen pericarp, roselle, red cabbage, Thai berry, black rice and blue pea were fabricated. Their photo-to-current conversion efficiencies and stability were examined. Pre-concentrated extracts were obtained by solid phase extraction (SPE) using C18 cartridge. The results obviously showed that all pre-concentrated extracts performed on photovoltaic performances in DSSCs better than crude extracts except for mangosteen pericarp. The DSSC sensitized by pre-concentrated anthocyanin from roselle and red cabbage showed maximum current efficiency η = 0.71% while DSSC sensitized by crude anthocyanin from mangosteen pericarp reached maximum efficiency η = 0.97%. In addition, pre-concentrated extract based cells possess more stability than those of crude extract based cells. This indicates that pre-concentration of anthocyanin via SPE method is very effective for DSSCs based on good photovoltaic performance and stability. The DFT/TDDFT calculations of electronic and photoelectrochemical properties of the major anthocyanins found in the samples are employed to support the experimental results.

Impact of the electron-transport layer on the performance of solution-processed small-molecule organic solar cells.

PubMed

Long, Guankui; Wan, Xiangjian; Kan, Bin; Hu, Zhicheng; Yang, Xuan; Zhang, Yi; Zhang, Mingtao; Wu, Hongbing; Huang, Fei; Su, Shijian; Cao, Yong; Chen, Yongsheng

2014-08-01

Although the performance of polymer solar cells has been improved significantly recently through careful optimization with different interlayers for the same materials, more improvement is needed in this respect for small-molecule-based solar cells, particularly for the electron-transport layers (ETLs). In this work, three different solution-processed ETLs, PFN, ZnO nanoparticles, and LiF, were investigated and compared in the performance of small-molecule-based devices, and power conversion efficiencies (PCEs) of 8.32, 7.30, and 7.38% were achieved, respectively. The mechanism for the ETL-induced enhancement has been studied, and different ETLs have a significantly different impact on the device performance. The clearly improved performance of PFN is attributed to the combination of reduced bimolecular recombination and increased effective photon absorption in the active layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ebselen Preserves Tissue-Engineered Cell Sheets and their Stem Cells in Hypothermic Conditions

PubMed Central

Katori, Ryosuke; Hayashi, Ryuhei; Kobayashi, Yuki; Kobayashi, Eiji; Nishida, Kohji

2016-01-01

Clinical trials have been performed using autologous tissue-engineered epithelial cell sheets for corneal regenerative medicine. To improve stem cell-based therapy for convenient clinical practice, new techniques are required for preserving reconstructed tissues and their stem/progenitor cells until they are ready for use. In the present study, we screened potential preservative agents and developed a novel medium for preserving the cell sheets and their stem/progenitor cells; the effects were evaluated with a luciferase-based viability assay. Nrf2 activators, specifically ebselen, could maintain high ATP levels during preservation. Ebselen also showed a strong influence on maintenance of the viability, morphology, and stem cell function of the cell sheets preserved under hypothermia by protecting them from reactive oxygen species-induced damage. Furthermore, ebselen drastically improved the preservation performance of human cornea tissues and their stem cells. Therefore, ebselen shows good potential as a useful preservation agent in regenerative medicine as well as in cornea transplantation. PMID:27966584

Ebselen Preserves Tissue-Engineered Cell Sheets and their Stem Cells in Hypothermic Conditions.

PubMed

Katori, Ryosuke; Hayashi, Ryuhei; Kobayashi, Yuki; Kobayashi, Eiji; Nishida, Kohji

2016-12-14

Clinical trials have been performed using autologous tissue-engineered epithelial cell sheets for corneal regenerative medicine. To improve stem cell-based therapy for convenient clinical practice, new techniques are required for preserving reconstructed tissues and their stem/progenitor cells until they are ready for use. In the present study, we screened potential preservative agents and developed a novel medium for preserving the cell sheets and their stem/progenitor cells; the effects were evaluated with a luciferase-based viability assay. Nrf2 activators, specifically ebselen, could maintain high ATP levels during preservation. Ebselen also showed a strong influence on maintenance of the viability, morphology, and stem cell function of the cell sheets preserved under hypothermia by protecting them from reactive oxygen species-induced damage. Furthermore, ebselen drastically improved the preservation performance of human cornea tissues and their stem cells. Therefore, ebselen shows good potential as a useful preservation agent in regenerative medicine as well as in cornea transplantation.

MATERIAL AND PROCESS DEVELOPMENT LEADING TO ECONOMICAL HIGH-PERFORMANCE THIN-FILM SOLID OXIDE FUEL CELLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jie Guan; Atul Verma; Nguyen Minh

2003-04-01

This document summarizes the technical progress from September 2002 to March 2003 for the program, Material and Process Development Leading to Economical High-Performance Thin-Film Solid Oxide Fuel Cells, contract number DE-AC26-00NT40711. The causes have been identified for the unstable open circuit voltage (OCV) and low performance exhibited by the anode-supported lanthanum gallate based cells from the earlier development. Promising results have been obtained in the area of synthesis of electrolyte and cathode powders, which showed excellent sintering and densification at low temperatures. The fabrication of cells using tapecalendering process for anode-supported thin lanthanum gallate electrolyte cells and their performance optimizationmore » is in progress.« less

Sensitivity of solar-cell performance to atmospheric variables. 2: Dissimilar cells at several locations

NASA Technical Reports Server (NTRS)

Klucher, T. M.; Hart, R. E.

1976-01-01

Several solar cells having dissimilar spectral response curves and cell construction were measured at various locations in the United States to determine sensitivity of cell performance to atmospheric water vapor and turbidity. The locations selected represent a broad range of summer atmospheric conditions, from clear and dry to turbid and humid. Cell short circuit current under direct normal incidence sunlight, the intensity, water vapor and turbidity were measured. Regression equations were developed from the limited data base in order to provide a single method of prediction of cell current sensitivity to the atmospheric variables.

Molybdenum dioxide-based anode for solid oxide fuel cell applications

NASA Astrophysics Data System (ADS)

Kwon, Byeong Wan; Ellefson, Caleb; Breit, Joe; Kim, Jinsoo; Grant Norton, M.; Ha, Su

2013-12-01

The present paper describes the fabrication and performance of a molybdenum dioxide (MoO2)-based anode for liquid hydrocarbon/oxygenated hydrocarbon-fueled solid oxide fuel cells (SOFCs). These fuel cells first internally reform the complex liquid fuel into carbon fragments and hydrogen, which are then electrochemically oxidized to produce electrical energy without external fuel processors. The MoO2-based anode was fabricated on to an yttria-stabilized zirconia (YSZ) electrolyte via combined electrostatic spray deposition (ESD) and direct painting methods. The cell performance was measured by directly feeding liquid fuels such as n-dodecane (i.e., a model diesel/kerosene fuel) or biodiesel (i.e., a future biomass-based liquid fuel) to the MoO2-based anode at 850 °C. The maximum initial power densities obtained from our MoO2-based SOFC were 34 mW cm-2 and 45 mW cm-2 using n-dodecane and biodiesel, respectively. The initial power density of the MoO2-based SOFC was improved up to 2500 mW cm-2 by optimizing the porosity of the MoO2-based anode. To test the long-term stability of the MoO2-based anode SOFC against coking, n-dodecane was continuously fed into the cell for 24 h at the open circuit voltage (OCV). During long-term testing, voltage-current density (V-I) plots were periodically obtained and they showed no significant changes over the operation time. Microstructural examination of the tested cells indicated that the MoO2-based anode displayed negligible coke formation, which explains its stability. On the other hand, SOFCs with conventional nickel (Ni)-based anodes under the same operating conditions showed a significant amount of coke formation on the metal surface, which led to a rapid drop in cell performance. Hence, the present work demonstrates that MoO2-based anodes exhibit outstanding tolerance to coke formation. This result opens up the opportunity for more efficiently generating electrical energy from both existing transportation and next generation biomass-derived liquid fuels using liquid hydrocarbon/oxygenated hydrocarbon-fueled SOFCs.

Poly(ethylene glycol)-[60]Fullerene-Based Materials for Perovskite Solar Cells with Improved Moisture Resistance and Reduced Hysteresis.

PubMed

Collavini, Silvia; Saliba, Michael; Tress, Wolfgang R; Holzhey, Philippe J; Völker, Sebastian F; Domanski, Konrad; Turren-Cruz, Silver H; Ummadisingu, Amita; Zakeeruddin, Shaik M; Hagfeldt, Anders; Grätzel, Michael; Delgado, Juan L

2018-03-22

A series of [60]fullerenes covalently functionalized with the polymer poly(ethylene glycol) is presented. These new [60]fullerene-based materials have been incorporated as additives in CH 3 NH 3 PbI 3 (MAPbI 3 ), the most common organic-inorganic perovskite used in perovskite solar cells. The extensive photovoltaic study performed by using these materials shows several beneficial effects on the performance of these cells, including a reduction in hysteresis and an increased stability against moisture, whereby the solar cells retain up to 97 % of their initial power conversion efficiency in an ambient atmosphere. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell-Based Microarrays for In Vitro Toxicology

NASA Astrophysics Data System (ADS)

Wegener, Joachim

2015-07-01

DNA/RNA and protein microarrays have proven their outstanding bioanalytical performance throughout the past decades, given the unprecedented level of parallelization by which molecular recognition assays can be performed and analyzed. Cell microarrays (CMAs) make use of similar construction principles. They are applied to profile a given cell population with respect to the expression of specific molecular markers and also to measure functional cell responses to drugs and chemicals. This review focuses on the use of cell-based microarrays for assessing the cytotoxicity of drugs, toxins, or chemicals in general. It also summarizes CMA construction principles with respect to the cell types that are used for such microarrays, the readout parameters to assess toxicity, and the various formats that have been established and applied. The review ends with a critical comparison of CMAs and well-established microtiter plate (MTP) approaches.

New bimetallic EMF cell shows promise in direct energy conversion

NASA Technical Reports Server (NTRS)

Hesson, J. C.; Shimotake, H.

1968-01-01

Concentration cell, based upon a thermally regenerative cell principle, produces electrical energy from any large heat source. This experimental bimetallic EMF cell uses a sodium-bismuth alloy cathode and a pure liquid sodium anode. The cell exhibits reliability, corrosion resistance, and high current density performance.

Convective Array Cooling for a Solar Powered Aircraft

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.; Dolce, James (Technical Monitor)

2003-01-01

A general characteristic of photovoltaics is that they increase in efficiency as their operating temperature decreases. Based on this principal, the ability to increase a solar aircraft's performance by cooling the solar cells was examined. The solar cells were cooled by channeling some air underneath the cells and providing a convective cooling path to the back side of the array. A full energy balance and flow analysis of the air within the cooling passage was performed. The analysis was first performed on a preliminary level to estimate the benefits of the cooling passage. This analysis established a clear benefit to the cooling passage. Based on these results a more detailed analysis was performed. From this cell temperatures were calculated and array output power throughout a day period were determined with and without the cooling passage. The results showed that if the flow through the cooling passage remained laminar then the benefit in increased output power more than offset the drag induced by the cooling passage.

A continuous-exchange cell-free protein synthesis system based on extracts from cultured insect cells.

PubMed

Stech, Marlitt; Quast, Robert B; Sachse, Rita; Schulze, Corina; Wüstenhagen, Doreen A; Kubick, Stefan

2014-01-01

In this study, we present a novel technique for the synthesis of complex prokaryotic and eukaryotic proteins by using a continuous-exchange cell-free (CECF) protein synthesis system based on extracts from cultured insect cells. Our approach consists of two basic elements: First, protein synthesis is performed in insect cell lysates which harbor endogenous microsomal vesicles, enabling a translocation of de novo synthesized target proteins into the lumen of the insect vesicles or, in the case of membrane proteins, their embedding into a natural membrane scaffold. Second, cell-free reactions are performed in a two chamber dialysis device for 48 h. The combination of the eukaryotic cell-free translation system based on insect cell extracts and the CECF translation system results in significantly prolonged reaction life times and increased protein yields compared to conventional batch reactions. In this context, we demonstrate the synthesis of various representative model proteins, among them cytosolic proteins, pharmacological relevant membrane proteins and glycosylated proteins in an endotoxin-free environment. Furthermore, the cell-free system used in this study is well-suited for the synthesis of biologically active tissue-type-plasminogen activator, a complex eukaryotic protein harboring multiple disulfide bonds.

A Continuous-Exchange Cell-Free Protein Synthesis System Based on Extracts from Cultured Insect Cells

PubMed Central

Stech, Marlitt; Quast, Robert B.; Sachse, Rita; Schulze, Corina; Wüstenhagen, Doreen A.; Kubick, Stefan

2014-01-01

In this study, we present a novel technique for the synthesis of complex prokaryotic and eukaryotic proteins by using a continuous-exchange cell-free (CECF) protein synthesis system based on extracts from cultured insect cells. Our approach consists of two basic elements: First, protein synthesis is performed in insect cell lysates which harbor endogenous microsomal vesicles, enabling a translocation of de novo synthesized target proteins into the lumen of the insect vesicles or, in the case of membrane proteins, their embedding into a natural membrane scaffold. Second, cell-free reactions are performed in a two chamber dialysis device for 48 h. The combination of the eukaryotic cell-free translation system based on insect cell extracts and the CECF translation system results in significantly prolonged reaction life times and increased protein yields compared to conventional batch reactions. In this context, we demonstrate the synthesis of various representative model proteins, among them cytosolic proteins, pharmacological relevant membrane proteins and glycosylated proteins in an endotoxin-free environment. Furthermore, the cell-free system used in this study is well-suited for the synthesis of biologically active tissue-type-plasminogen activator, a complex eukaryotic protein harboring multiple disulfide bonds. PMID:24804975

Location Dependency and Antenna/Body/Sensor-Lead Interaction Effects in a Cell-Phone Based GSM 1800 Telemedicine Link

DTIC Science & Technology

2001-10-25

The error-free requirement of today’s cell - phone based telemedicine systems demands investigations into the potential causes of service degradation...to the handset’s antenna can have on system performance Changes in lead orientation in the near field of the radiating unit ( cell - phone & antenna

Φ-score: A cell-to-cell phenotypic scoring method for sensitive and selective hit discovery in cell-based assays.

PubMed

Guyon, Laurent; Lajaunie, Christian; Fer, Frédéric; Bhajun, Ricky; Sulpice, Eric; Pinna, Guillaume; Campalans, Anna; Radicella, J Pablo; Rouillier, Philippe; Mary, Mélissa; Combe, Stéphanie; Obeid, Patricia; Vert, Jean-Philippe; Gidrol, Xavier

2015-09-18

Phenotypic screening monitors phenotypic changes induced by perturbations, including those generated by drugs or RNA interference. Currently-used methods for scoring screen hits have proven to be problematic, particularly when applied to physiologically relevant conditions such as low cell numbers or inefficient transfection. Here, we describe the Φ-score, which is a novel scoring method for the identification of phenotypic modifiers or hits in cell-based screens. Φ-score performance was assessed with simulations, a validation experiment and its application to gene identification in a large-scale RNAi screen. Using robust statistics and a variance model, we demonstrated that the Φ-score showed better sensitivity, selectivity and reproducibility compared to classical approaches. The improved performance of the Φ-score paves the way for cell-based screening of primary cells, which are often difficult to obtain from patients in sufficient numbers. We also describe a dedicated merging procedure to pool scores from small interfering RNAs targeting the same gene so as to provide improved visualization and hit selection.

Φ-score: A cell-to-cell phenotypic scoring method for sensitive and selective hit discovery in cell-based assays

PubMed Central

Guyon, Laurent; Lajaunie, Christian; fer, Frédéric; bhajun, Ricky; sulpice, Eric; pinna, Guillaume; campalans, Anna; radicella, J. Pablo; rouillier, Philippe; mary, Mélissa; combe, Stéphanie; obeid, Patricia; vert, Jean-Philippe; gidrol, Xavier

2015-01-01

Phenotypic screening monitors phenotypic changes induced by perturbations, including those generated by drugs or RNA interference. Currently-used methods for scoring screen hits have proven to be problematic, particularly when applied to physiologically relevant conditions such as low cell numbers or inefficient transfection. Here, we describe the Φ-score, which is a novel scoring method for the identification of phenotypic modifiers or hits in cell-based screens. Φ-score performance was assessed with simulations, a validation experiment and its application to gene identification in a large-scale RNAi screen. Using robust statistics and a variance model, we demonstrated that the Φ-score showed better sensitivity, selectivity and reproducibility compared to classical approaches. The improved performance of the Φ-score paves the way for cell-based screening of primary cells, which are often difficult to obtain from patients in sufficient numbers. We also describe a dedicated merging procedure to pool scores from small interfering RNAs targeting the same gene so as to provide improved visualization and hit selection. PMID:26382112

Improving anticancer drug development begins with cell culture: misinformation perpetrated by the misuse of cytotoxicity assays.

PubMed

Eastman, Alan

2017-01-31

The high failure rate of anticancer drug discovery and development has consumed billions of dollars annually. While many explanations have been provided, I believe that misinformation arising from inappropriate cell-based screens has been completely over-looked. Most cell culture experiments are irrelevant to how drugs are subsequently administered to patients. Usually, drug development focuses on growth inhibition rather than cell killing. Drugs are selected based on continuous incubation of cells, then frequently administered to the patient as a bolus. Target identification and validation is often performed by gene suppression that inevitably mimics continuous target inhibition. Drug concentrations in vitro frequently far exceed in vivo concentrations. Studies of drug synergy are performed at sub-optimal concentrations. And the focus on a limited number of cell lines can misrepresent the potential efficacy in a patient population. The intent of this review is to encourage more appropriate experimental design and data interpretation, and to improve drug development in the area of cell-based assays. Application of these principles should greatly enhance the successful translation of novel drugs to the patient.

Speech recognition systems on the Cell Broadband Engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Y; Jones, H; Vaidya, S

In this paper we describe our design, implementation, and first results of a prototype connected-phoneme-based speech recognition system on the Cell Broadband Engine{trademark} (Cell/B.E.). Automatic speech recognition decodes speech samples into plain text (other representations are possible) and must process samples at real-time rates. Fortunately, the computational tasks involved in this pipeline are highly data-parallel and can receive significant hardware acceleration from vector-streaming architectures such as the Cell/B.E. Identifying and exploiting these parallelism opportunities is challenging, but also critical to improving system performance. We observed, from our initial performance timings, that a single Cell/B.E. processor can recognize speech from thousandsmore » of simultaneous voice channels in real time--a channel density that is orders-of-magnitude greater than the capacity of existing software speech recognizers based on CPUs (central processing units). This result emphasizes the potential for Cell/B.E.-based speech recognition and will likely lead to the future development of production speech systems using Cell/B.E. clusters.« less

Development and fabrication of large vented nickel-zinc cells

NASA Technical Reports Server (NTRS)

Donnel, C. P., III

1975-01-01

A preliminary cell design for a 300AH vented nickel-zinc cell was established based on volume requirements and cell component materials selected by NASA Lewis Research Center. A 100AH cell configuration was derived from the 300AH cell design utilizing the same size electrodes, separators, and cell terminal hardware. The first cells fabricated were four groups of three cells each in the 100AH size. These 100AH experimental nickel-zinc cells had as common components the nickel positive electrodes (GFM), flexible inorganic separator (GFM) bags on the negative electrodes, pressed powder zinc oxide electrodes, and cell containers with hardware. The variations introduced were four differing electrolyte absorber (interseparator) systems used to encase the nickel positive electrodes of each cell group. The four groups of 100AH experimental vented nickel-zinc cells were tested to determine, based on cell performance, the best two interseparator systems. Using the two interseparator systems, two groups of experimental 300AH cells were fabricated. Each group of three cells differed only in the interseparator material used. The six cells were filled, formed and tested to evaluate the interseparator materials and investigate the performance characteristics of the 300AH cell configuration and its components.

Dye-Incorporated Polynaphthalenediimide Acceptor for Additive-Free High-Performance All-Polymer Solar Cells.

PubMed

Chen, Dong; Yao, Jia; Chen, Lie; Yin, Jingping; Lv, Ruizhi; Huang, Bin; Liu, Siqi; Zhang, Zhi-Guo; Yang, Chunhe; Chen, Yiwang; Li, Yongfang

2018-04-16

All-polymer solar cells (all-PSCs) can offer unique advantages for applications in flexible devices, and naphthalene diimide (NDI)-based polymer acceptors are the widely used polymer acceptors. However, their power conversion efficiency (PCE) still lags behind that of state-of-the-art polymer solar cells, due to low light absorption, suboptimal energy levels and the strong aggregation of the NDI-based polymer acceptor. Herein, a rhodanine-based dye molecule was introduced into the NDI-based polymer acceptor by simple random copolymerization and showed an improved light absorption coefficient, an up-shifted lowest unoccupied molecular orbital level and reduced crystallization. Consequently, additive-free all-PSCs demonstrated a high PCE of 8.13 %, which is one of the highest performance characteristics reported for all-PSCs to date. These results indicate that incorporating a dye into the n-type polymer gives insight into the precise design of high-performance polymer acceptors for all-PSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis and optimization of solid oxide fuel cell-based auxiliary power units using a generic zero-dimensional fuel cell model

NASA Astrophysics Data System (ADS)

Göll, S.; Samsun, R. C.; Peters, R.

Fuel-cell-based auxiliary power units can help to reduce fuel consumption and emissions in transportation. For this application, the combination of solid oxide fuel cells (SOFCs) with upstream fuel processing by autothermal reforming (ATR) is seen as a highly favorable configuration. Notwithstanding the necessity to improve each single component, an optimized architecture of the fuel cell system as a whole must be achieved. To enable model-based analyses, a system-level approach is proposed in which the fuel cell system is modeled as a multi-stage thermo-chemical process using the "flowsheeting" environment PRO/II™. Therein, the SOFC stack and the ATR are characterized entirely by corresponding thermodynamic processes together with global performance parameters. The developed model is then used to achieve an optimal system layout by comparing different system architectures. A system with anode and cathode off-gas recycling was identified to have the highest electric system efficiency. Taking this system as a basis, the potential for further performance enhancement was evaluated by varying four parameters characterizing different system components. Using methods from the design and analysis of experiments, the effects of these parameters and of their interactions were quantified, leading to an overall optimized system with encouraging performance data.

Improving the Response of a Load Cell by Using Optimal Filtering

PubMed Central

Hernandez, Wilmar

2006-01-01

Load cells are transducers used to measure force or weight. Despite the fact that there is a wide variety of load cells, most of these transducers that are used in the weighing industry are based on strain gauges. In this paper, an s-beam load cell based on strain gauges was suitably assembled to the mechanical structure of several seats of a bus under performance tests and used to measure the resistance of their mechanical structure to tension forces applied horizontally to the seats being tested. The load cell was buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency spectrum and its performance was improved by using a recursive least-squares (RLS) lattice algorithm. The experimental results are satisfactory and a significant improvement in the signal-to-noise ratio at the system output of 27 dB was achieved, which is a good performance factor for judging the quality of the system.

TiO2-ZnS Cascade Electron Transport Layer for Efficient Formamidinium Tin Iodide Perovskite Solar Cells.

PubMed

Ke, Weijun; Stoumpos, Constantinos C; Logsdon, Jenna Leigh; Wasielewski, Michael R; Yan, Yanfa; Fang, Guojia; Kanatzidis, Mercouri G

2016-11-16

Achieving high open-circuit voltage (V oc ) for tin-based perovskite solar cells is challenging. Here, we demonstrate that a ZnS interfacial layer can improve the V oc and photovoltaic performance of formamidinium tin iodide (FASnI 3 ) perovskite solar cells. The TiO 2 -ZnS electron transporting layer (ETL) with cascade conduction band structure can effectively reduce the interfacial charge recombination and facilitate electron transfer. Our best-performing FASnI 3 perovskite solar cell using the cascaded TiO 2 -ZnS ETL has achieved a power conversion efficiency of 5.27%, with a higher V oc of 0.380 V, a short-circuit current density of 23.09 mA cm -2 , and a fill factor of 60.01%. The cascade structure is further validated with a TiO 2 -CdS ETL. Our results suggest a new approach for further improving the performance of tin-based perovskite solar cells with a higher V oc .

Influence of thermal annealing-induced molecular aggregation on film properties and photovoltaic performance of bulk heterojunction solar cells based on a squaraine dye

NASA Astrophysics Data System (ADS)

Zhang, Pengpeng; Ling, Zhitian; Chen, Guo; Wei, Bin

2018-06-01

Squaraine (SQ) dyes have been considered as efficient photoactive materials for organic solar cells. In this work, we purposely controlled the molecular aggregation of an SQ dye, 2,4-bis[4-(N,N-dibutylamino)-2-dihydroxyphenyl] SQ (DBSQ-(OH)2) in the DBSQ(OH)2:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film by using the thermal annealing method, to study the influence of the molecular aggregation on film properties as well as the photovoltaic performance of DBSQ(OH)2:PCBM-based bulk heterojunction (BHJ) solar cells. Our results demonstrate that thermal annealing may change the aggregation behavior of DBSQ(OH)2 in the DBSQ(OH)2:PCBM film, and thus significantly influence the surface morphology, optical and electrical properties of the blend film, as well as the photovoltaic performance of DBSQ(OH)2:PCBM BHJ cells.

Influence of thermal annealing-induced molecular aggregation on film properties and photovoltaic performance of bulk heterojunction solar cells based on a squaraine dye

NASA Astrophysics Data System (ADS)

Zhang, Pengpeng; Ling, Zhitian; Chen, Guo; Wei, Bin

2018-04-01

Squaraine (SQ) dyes have been considered as efficient photoactive materials for organic solar cells. In this work, we purposely controlled the molecular aggregation of an SQ dye, 2,4-bis[4-(N,N-dibutylamino)-2-dihydroxyphenyl] SQ (DBSQ-(OH)2) in the DBSQ(OH)2:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film by using the thermal annealing method, to study the influence of the molecular aggregation on film properties as well as the photovoltaic performance of DBSQ(OH)2:PCBM-based bulk heterojunction (BHJ) solar cells. Our results demonstrate that thermal annealing may change the aggregation behavior of DBSQ(OH)2 in the DBSQ(OH)2:PCBM film, and thus significantly influence the surface morphology, optical and electrical properties of the blend film, as well as the photovoltaic performance of DBSQ(OH)2:PCBM BHJ cells.

Structural and electronic properties of the heterointerfaces for Cu2ZnSnS4 photovoltaic cells: a density-functional theory study.

PubMed

Xiao, W; Wang, J N; Wang, J W; Huang, G J; Cheng, L; Jiang, L J; Wang, L G

2016-04-28

The quaternary compound semiconductor Cu2ZnSnS4 (CZTS) is a promising photovoltaic absorber material for thin-film solar cell applications. Density-functional theory calculations have been performed to investigate the structural and electronic properties of the CdS/CZTS heterointerfaces in CZTS-based cells. We find that CdS favors epitaxial growth on the Cu-Zn plane of CZTS along the direction of [100], which can eliminate the effects of the wrong bonds at the interfaces and enhance the energetic barrier for charge carrier recombination across the interfaces with an increased band gap. The band alignment is calculated for the epitaxial CZTS/CdS heterointerface by employing the HSE06 functional and the results show a type-II band alignment with VBO and CBO values of 0.95 eV and -0.05 eV, respectively. Also, the experimental phenomenon of Zn segregation at CdS/CZTS interfaces is corroborated. Zn segregation can enhance the stability of the heterointerfaces, but damage the solar cell performance by decreasing the band gap when the Zn concentration is sufficiently high. We show that besides the defects and undesired phases in CZTS, the heterointerfaces between the absorption layers (CZTS) and the buffer layer (CdS) can also be an important factor that affects the performance of CZTS cells. The present work provides a theoretical base for engineering the heterointerfaces and achieving better performance of CZTS-based solar cells.

Highly-flexible fibre battery incorporating polypyrrole cathode and carbon nanotubes anode

NASA Astrophysics Data System (ADS)

Wang, J.; Wang, C. Y.; Too, C. O.; Wallace, G. G.

The development of highly-flexible fibre batteries based on a conducting polymer and single-wall carbon nanotubes (SWNTs) is described. Initially, polypyrrole-hexafluorophosphate (PPy/PF 6) and SWNTs are tested in lithium cells to ascertain their performance. Based on the results, fibre batteries consisting of a PPy/PF 6 cathode and an anode based on SWNTs are fabricated and tested in both a "flooded cell" and 'dry cell', arrangement.

Highly sensitive detection of cancer cells with an electrochemical cytosensor based on boronic acid functional polythiophene.

PubMed

Dervisevic, Muamer; Senel, Mehmet; Sagir, Tugba; Isik, Sevim

2017-04-15

The detection of cancer cells through important molecular recognition target such as sialic acid is significant for the clinical diagnosis and treatment. There are many electrochemical cytosensors developed for cancer cells detection but most of them have complicated fabrication processes which results in poor reproducibility and reliability. In this study, a simple, low-cost, and highly sensitive electrochemical cytosensor was designed based on boronic acid-functionalized polythiophene. In cytosensors fabrication simple single-step procedure was used which includes coating pencil graphite electrode (PGE) by means of electro-polymerization of 3-Thienyl boronic acid and Thiophen. Electrochemical impedance spectroscopy and cyclic voltammetry were used as an analytical methods to optimize and measure analytical performances of PGE/P(TBA 0.5 Th 0.5 ) based electrode. Cytosensor showed extremely good analytical performances in detection of cancer cells with linear rage of 1×10 1 to 1×10 6 cellsmL -1 exhibiting low detection limit of 10 cellsmL -1 and incubation time of 10min. Next to excellent analytical performances, it showed high selectivity towards AGS cancer cells when compared to HEK 293 normal cells and bone marrow mesenchymal stem cells (BM-hMSCs). This method is promising for future applications in early stage cancer diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Method for Predicting the Energy Characteristics of Li-Ion Cells Designed for High Specific Energy

NASA Technical Reports Server (NTRS)

Bennett, William, R.

2012-01-01

Novel electrode materials with increased specific capacity and voltage performance are critical to the NASA goals for developing Li-ion batteries with increased specific energy and energy density. Although performance metrics of the individual electrodes are critically important, a fundamental understanding of the interactions of electrodes in a full cell is essential to achieving the desired performance, and for establishing meaningful goals for electrode performance in the first place. This paper presents design considerations for matching positive and negative electrodes in a viable design. Methods for predicting cell-level performance, based on laboratory data for individual electrodes, are presented and discussed.

PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems.

PubMed

Ghaffarizadeh, Ahmadreza; Heiland, Randy; Friedman, Samuel H; Mumenthaler, Shannon M; Macklin, Paul

2018-02-01

Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal "virtual laboratory" for such multicellular systems simulates both the biochemical microenvironment (the "stage") and many mechanically and biochemically interacting cells (the "players" upon the stage). PhysiCell-physics-based multicellular simulator-is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility "out of the box." The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a "cellular cargo delivery" system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also represents a significant independent code base for replicating results from other simulation platforms. The PhysiCell source code, examples, documentation, and support are available under the BSD license at http://PhysiCell.MathCancer.org and http://PhysiCell.sf.net.

Continuous Non-Destructive Monitoring of Cell Health Using Impedance Based Interdigitated Electrode Structured Sensors

NASA Astrophysics Data System (ADS)

Paschero, Anna; McLoughlin, Eve; Moore, Eric

2011-06-01

This article examines some preliminary tests which were performed in order to evaluate the best electrode configuration (width and spacing) for cell culture analyses. Biochips packaged with indium tin oxide (ITO) interdigitated electrodes (IDEs) were used to perform impedance measurements on A549 cells cultured on the surface of the biochip. Several tests were carried out using a 10 mM solution of Sodium Chloride (NaCl), cell medium and the cell culture itself to characterize some of the configurations already fabricated in the facilities at Tyndall National Institute.

Evaluation of solar cells for potential space satellite power applications

NASA Technical Reports Server (NTRS)

1977-01-01

The evaluation focused on the following subjects: (1) the relative merits of alternative solar cell materials, based on performance and availability, (2) the best manufacturing methods for various solar cell options and the effects of extremely large production volumes on their ultimate costs and operational characteristics, (3) the areas of uncertainty in achieving large solar cell production volumes, (4) the effects of concentration ratios on solar array mass and system performance, (5) the factors influencing solar cell life in the radiation environment during transport to and in geosynchronous orbit, and (6) the merits of conducting solar cell manufacturing operations in space.

Influence of different TiO2 blocking films on the photovoltaic performance of perovskite solar cells

NASA Astrophysics Data System (ADS)

Zhang, Chenxi; Luo, Yudan; Chen, Xiaohong; Ou-Yang, Wei; Chen, Yiwei; Sun, Zhuo; Huang, Sumei

2016-12-01

Organolead trihalide perovskite materials have been successfully used as light absorbers in efficient photovoltaic (PV) cells. Cell structures based on mesoscopic metal oxides and planar heterojunctions have already demonstrated very impressive and brisk advances, holding great potential to grow into a mature PV technology. High power conversion efficiency (PCE) values have been obtained from the mesoscopic configuration in which a few hundred nano-meter thick mesoporous scaffold (e.g. TiO2 or Al2O3) infiltrated by perovskite absorber was sandwiched between the electron and hole transport layers. A uniform and compact hole-blocking layer is necessary for high efficient perovskite-based thin film solar cells. In this study, we investigated the characteristics of TiO2 compact layer using various methods and its effects on the PV performance of perovskite solar cells. TiO2 compact layer was prepared by a sol-gel method based on titanium isopropoxide and HCl, spin-coating of titanium diisopropoxide bis (acetylacetonate), screen-printing of Dyesol's bocking layer titania paste, and a chemical bath deposition (CBD) technique via hydrolysis of TiCl4, respectively. The morphological and micro-structural properties of the formed compact TiO2 layers were characterized by scanning electronic microscopy and X-ray diffraction. The analyses of devices performance characteristics showed that surface morphologies of TiO2 compact films played a critical role in affecting the efficiencies. The nanocrystalline TiO2 film deposited via the CBD route acts as the most efficient hole-blocking layer and achieves the best performance in perovskite solar cells. The CBD-based TiO2 compact and dense layer offers a small series resistance and a large recombination resistance inside the device, and makes it possible to achieve a high power conversion efficiency of 12.80%.

GaSb and Ga1-xInxSb Thermophotovoltaic Cells using Diffused Junction Technology in Bulk Substrates

NASA Astrophysics Data System (ADS)

Dutta, P. S.; Borrego, J. M.; Ehsani, H.; Rajagopalan, G.; Bhat, I. B.; Gutmann, R. J.; Nichols, G.; Baldasaro, P. F.

2003-01-01

This paper presents results of experimental and theoretical research on antimonide- based thermophotovoltaic (TPV) materials and cells. The topics discussed include: growth of large diameter ternary GaInSb bulk crystals, substrate preparation, diffused junction processes, cell fabrication and characterization, and, cell modeling. Ternary GaInSb boules up to 2 inches in diameter have been grown using the vertical Bridgman technique with a novel self solute feeding technique. A single step diffusion process followed by precise etching of the diffused layer has been developed to obtain a diffusion profile appropriate for high efficiency, p-n junction GaSb and GaInSb thermophotovoltaic cells. The optimum junction depth to obtain the highest quantum efficiency and open circuit voltage has been identified based on diffusion lengths (or minority carrier lifetimes), carrier mobility and experimental diffused impurity profiles. Theoretical assessment of the performance of ternary (GaInSb) and binary (GaSb) cells fabricated by Zn diffusion in bulk substrates has been performed using PC-1D one-dimensional computer simulations. Several factors affecting the cell performances such as the effects of emitter doping profile, emitter thickness and recombination mechanisms (Auger, radiative and Shockley-Read-Hall), the advantages of surface passivation and the impact of dark current due to the metallic grid will be discussed. The conditions needed for diffused junction cells on ternary and binary substrates to achieve similar performance to the epitaxially grown lattice- matched quaternary cells are identified.

A Field-Portable Cell Analyzer without a Microscope and Reagents.

PubMed

Seo, Dongmin; Oh, Sangwoo; Lee, Moonjin; Hwang, Yongha; Seo, Sungkyu

2017-12-29

This paper demonstrates a commercial-level field-portable lens-free cell analyzer called the NaviCell (No-stain and Automated Versatile Innovative cell analyzer) capable of automatically analyzing cell count and viability without employing an optical microscope and reagents. Based on the lens-free shadow imaging technique, the NaviCell (162 × 135 × 138 mm³ and 1.02 kg) has the advantage of providing analysis results with improved standard deviation between measurement results, owing to its large field of view. Importantly, the cell counting and viability testing can be analyzed without the use of any reagent, thereby simplifying the measurement procedure and reducing potential errors during sample preparation. In this study, the performance of the NaviCell for cell counting and viability testing was demonstrated using 13 and six cell lines, respectively. Based on the results of the hemocytometer ( de facto standard), the error rate (ER) and coefficient of variation (CV) of the NaviCell are approximately 3.27 and 2.16 times better than the commercial cell counter, respectively. The cell viability testing of the NaviCell also showed an ER and CV performance improvement of 5.09 and 1.8 times, respectively, demonstrating sufficient potential in the field of cell analysis.

An ultraviolet responsive hybrid solar cell based on titania/poly(3-hexylthiophene).

PubMed

Wu, Jihuai; Yue, Gentian; Xiao, Yaoming; Lin, Jianming; Huang, Miaoliang; Lan, Zhang; Tang, Qunwei; Huang, Yunfang; Fan, Leqing; Yin, Shu; Sato, Tsugio

2013-01-01

Here we present an ultraviolet responsive inorganic-organic hybrid solar cell based on titania/poly(3-hexylthiophene) (TiO(2)/P3HT) heterojuction. In this solar cell, TiO(2) is an ultraviolet light absorber and electronic conductor, P3HT is a hole conductor, the light-to-electrical conversion is realized by the cooperation for these two components. Doping ionic salt in P3HT polymer can improve the photovoltaic performance of the solar cell. Under ultraviolet light irradiation with intensity of 100 mW·cm(-2), the hybrid solar cell doped with 1.0 wt.% lithium iodide achieves an energy conversion efficiency of 1.28%, which is increased by 33.3% compared to that of the hybrid solar cell without lithium iodide doping. Our results open a novel sunlight irradiation field for solar energy utilization, demonstrate the feasibility of ultraviolet responsive solar cells, and provide a new route for enhancing the photovoltaic performance of solar cells.

An ultraviolet responsive hybrid solar cell based on titania/poly(3-hexylthiophene)

PubMed Central

Wu, Jihuai; Yue, Gentian; Xiao, Yaoming; Lin, Jianming; Huang, Miaoliang; Lan, Zhang; Tang, Qunwei; Huang, Yunfang; Fan, Leqing; Yin, Shu; Sato, Tsugio

2013-01-01

Here we present an ultraviolet responsive inorganic-organic hybrid solar cell based on titania/poly(3-hexylthiophene) (TiO2/P3HT) heterojuction. In this solar cell, TiO2 is an ultraviolet light absorber and electronic conductor, P3HT is a hole conductor, the light-to-electrical conversion is realized by the cooperation for these two components. Doping ionic salt in P3HT polymer can improve the photovoltaic performance of the solar cell. Under ultraviolet light irradiation with intensity of 100 mW·cm−2, the hybrid solar cell doped with 1.0 wt.% lithium iodide achieves an energy conversion efficiency of 1.28%, which is increased by 33.3% compared to that of the hybrid solar cell without lithium iodide doping. Our results open a novel sunlight irradiation field for solar energy utilization, demonstrate the feasibility of ultraviolet responsive solar cells, and provide a new route for enhancing the photovoltaic performance of solar cells. PMID:23412470

Axi-symmetric patterns of active polar filaments on spherical and composite surfaces

NASA Astrophysics Data System (ADS)

Srivastava, Pragya; Rao, Madan

2014-03-01

Experiments performed on Fission Yeast cells of cylindrical and spherical shapes, rod-shaped bacteria and reconstituted cylindrical liposomes suggest the influence of cell geometry on patterning of cortical actin. A theoretical model based on active hydrodynamic description of cortical actin that includes curvature-orientation coupling predicts spontaneous formation of acto-myosin rings, cables and nodes on cylindrical and spherical geometries [P. Srivastava et al, PRL 110, 168104(2013)]. Stability and dynamics of these patterns is also affected by the cellular shape and has been observed in experiments performed on Fission Yeast cells of spherical shape. Motivated by this, we study the stability and dynamics of axi-symmetric patterns of active polar filaments on the surfaces of spherical, saddle shaped and conical geometry and classify the stable steady state patterns on these surfaces. Based on the analysis of the fluorescence images of Myosin-II during ring slippage we propose a simple mechanical model for ring-sliding based on force balance and make quantitative comparison with the experiments performed on Fission Yeast cells. NSF Grant DMR-1004789 and Syracuse Soft Matter Program.

Hydrogen peroxide oxidant fuel cell systems for ultra-portable applications

NASA Technical Reports Server (NTRS)

Valdez, T. I.; Narayanan, S. R.

2001-01-01

This paper will address the issues of using hydrogen peroxide as an oxidant fuel in a miniature DMFC system. Cell performance for DMFC based fuel cells operating on hydrogen peroxide will be presented and discussed.

Characterisation of a hybrid, fuel-cell-based propulsion system for small unmanned aircraft

NASA Astrophysics Data System (ADS)

Verstraete, D.; Lehmkuehler, K.; Gong, A.; Harvey, J. R.; Brian, G.; Palmer, J. L.

2014-03-01

Advanced hybrid powerplants combining a fuel cell and battery can enable significantly higher endurance for small, electrically powered unmanned aircraft systems, compared with batteries alone. However, detailed investigations of the static and dynamic performance of such systems are required to address integration challenges. This article describes a series of tests used to characterise the Horizon Energy Systems' AeroStack hybrid, fuel-cell-based powertrain. The results demonstrate that a significant difference can exist between the dynamic performance of the fuel-cell system and its static polarisation curve, confirming the need for detailed measurements. The results also confirm that the AeroStack's lithium-polymer battery plays a crucial role in its response to dynamic load changes and protects the fuel cell from membrane dehydration and fuel starvation. At low static loads, the AeroStack fuel cell recharges the battery with currents up to 1 A, which leads to further differences with the polarisation curve.

Stretchable and Photocatalytically Renewable Electrochemical Sensor Based on Sandwich Nanonetworks for Real-Time Monitoring of Cells.

PubMed

Wang, Ya-Wen; Liu, Yan-Ling; Xu, Jia-Quan; Qin, Yu; Huang, Wei-Hua

2018-05-15

Stretchable electrochemical (EC) sensors have broad prospects in real-time monitoring of living cells and tissues owing to their excellent elasticity and deformability. However, the redox reaction products and cell secretions are easily adsorbed on the electrode, resulting in sensor fouling and passivation. Herein, we developed a stretchable and photocatalytically renewable EC sensor based on Au nanotubes (NTs) and TiO 2 nanowires (NWs) sandwich nanonetworks. The external Au NTs are used for EC sensing, and internal TiO 2 NWs provide photocatalytic performance to degrade contaminants, which endows the sensor with excellent EC performance, high photocatalytic activity, and favorable mechanical tensile property. This allows highly sensitive recycling monitoring of NO released from endothelial cells and 5-HT released from mast cells under their stretching states in real time, therefore providing a promising tool to unravel elastic and mechanically sensitive cells, tissues, and organs.

Facile and gram-scale synthesis of metal-free catalysts: toward realistic applications for fuel cells.

PubMed

Kim, Ok-Hee; Cho, Yong-Hun; Chung, Dong Young; Kim, Min Jeong; Yoo, Ji Mun; Park, Ji Eun; Choe, Heeman; Sung, Yung-Eun

2015-03-02

Although numerous reports on nonprecious metal catalysts for replacing expensive Pt-based catalysts have been published, few of these studies have demonstrated their practical application in fuel cells. In this work, we report graphitic carbon nitride and carbon nanofiber hybrid materials synthesized by a facile and gram-scale method via liquid-based reactions, without the use of toxic materials or a high pressure-high temperature reactor, for use as fuel cell cathodes. The resulting materials exhibited remarkable methanol tolerance, selectivity, and stability even without a metal dopant. Furthermore, these completely metal-free catalysts exhibited outstanding performance as cathode materials in an actual fuel cell device: a membrane electrode assembly with both acidic and alkaline polymer electrolytes. The fabrication method and remarkable performance of the single cell produced in this study represent progressive steps toward the realistic application of metal-free cathode electrocatalysts in fuel cells.

Facile and Gram-scale Synthesis of Metal-free Catalysts: Toward Realistic Applications for Fuel Cells

PubMed Central

Kim, Ok-Hee; Cho, Yong-Hun; Chung, Dong Young; Kim, Min Jeong; Yoo, Ji Mun; Park, Ji Eun; Choe, Heeman; Sung, Yung-Eun

2015-01-01

Although numerous reports on nonprecious metal catalysts for replacing expensive Pt-based catalysts have been published, few of these studies have demonstrated their practical application in fuel cells. In this work, we report graphitic carbon nitride and carbon nanofiber hybrid materials synthesized by a facile and gram-scale method via liquid-based reactions, without the use of toxic materials or a high pressure-high temperature reactor, for use as fuel cell cathodes. The resulting materials exhibited remarkable methanol tolerance, selectivity, and stability even without a metal dopant. Furthermore, these completely metal-free catalysts exhibited outstanding performance as cathode materials in an actual fuel cell device: a membrane electrode assembly with both acidic and alkaline polymer electrolytes. The fabrication method and remarkable performance of the single cell produced in this study represent progressive steps toward the realistic application of metal-free cathode electrocatalysts in fuel cells. PMID:25728910

A prefilter for mitigating PH 3 contamination of a Ni-YSZ anode

NASA Astrophysics Data System (ADS)

Xu, Chunchuan; Zondlo, John W.; Sabolsky, Edward M.

Ni-YSZ is used as the anode of a solid oxide fuel cell (SOFC) because it has excellent electrochemical performance for operation with coal-derived syngas. However, trace impurities, PH 3 H 2S AsH 3, and Sb in coal-syngas can cause SOFC degradation. Described here is a means of removing PH 3 impurity from syngas by using a Ni-based prefilter. In one test, a thin Ni-based filter was set upstream of a Ni-YSZ anode-supported SOFC. The SOFC was exposed to syngas with PH 3 under a constant current load at 800 °C. The filter decreased 20 ppm PH 3 in the feed to a level which did not degrade the SOFC for over 400 h until the filter became saturated. In another test, both H 2S and PH 3 were co-fed to the cell with Ni-based and Fe/Ni-based filters. The interaction between these two impurities did not significantly impact the filter performance with respect to PH 3 removal for both filter formulations. The cell performance was evaluated by current-voltage measurements and impedance spectroscopy. Post-mortem analyses of the cell and filter were performed by means of XRD, SEM/EDS and XPS. With proper filter design, the Ni-YSZ SOFC can operate on contaminated coal-syngas without degradation over a prescribed period of time.

Cell-based dose responses from open-well microchambers.

PubMed

Hamon, Morgan; Jambovane, Sachin; Bradley, Lauren; Khademhosseini, Ali; Hong, Jong Wook

2013-05-21

Cell-based assays play a critical role in discovery of new drugs and facilitating research in cancer, immunology, and stem cells. Conventionally, they are performed in Petri dishes, tubes, or well plates, using milliliters of reagents and thousands of cells to obtain one data point. Here, we are introducing a new platform to realize cell-based assay capable of increased throughput and greater sensitivity with a limited number of cells. We integrated an array of open-well microchambers into a gradient generation system. Consequently, cell-based dose responses were examined with a single device. We measured IC50 values of three cytotoxic chemicals, Triton X-100, H2O2, and cadmium chloride, as model compounds. The present system is highly suitable for the discovery of new drugs and studying the effect of chemicals on cell viability or mortality with limited samples and cells.

High-Performance Cells Containing Lithium Metal Anodes, LiNi0.6Co0.2Mn0.2O2 (NCM 622) Cathodes, and Fluoroethylene Carbonate-Based Electrolyte Solution with Practical Loading.

PubMed

Salitra, Gregory; Markevich, Elena; Afri, Michal; Talyosef, Yosef; Hartmann, Pascal; Kulisch, Joern; Sun, Yang-Kook; Aurbach, Doron

2018-06-13

We report on the highly stable lithium metal|LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622) cells with practical electrodes' loading of 3.3 mA h g -1 , which can undergo many hundreds of stable cycles, demonstrating high rate capability. A key issue was the use of fluoroethylene carbonate (FEC)-based electrolyte solutions (1 M LiPF 6 in FEC/dimethyl carbonate). Li|NCM 622 cells can be cycled at 1.5 mA cm -2 for more than 600 cycles, whereas symmetric Li|Li cells demonstrate stable performance for more than 1000 cycles even at higher areal capacity and current density. We attribute the excellent performance of both Li|NCM and Li|Li cells to the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in FEC-based electrolyte solutions. The composition of the SEI on the Li and the NCM electrodes is analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A drastic capacity fading of Li|NCM cells is observed, followed by spontaneous capacity recovery during prolonged cycling. This phenomenon depends on the current density and the amount of the electrolyte solution and relates to kinetic limitations because of SEI formation on the Li anodes in the FEC-based electrolyte solution.

An Analytical Performance Assessment of a Fuel Cell-powered, Small Electric Airplane

NASA Technical Reports Server (NTRS)

Berton, Jeffrey J.; Freeh, Joshua E.; Wickenheiser, Timothy J.

2003-01-01

Rapidly emerging fuel cell power technologies may be used to launch a new revolution of electric propulsion systems for light aircraft. Future small electric airplanes using fuel cell technologies hold the promise of high reliability, low maintenance, low noise, and with exception of water vapor zero emissions. This paper describes an analytical feasibility and performance assessment conducted by NASA's Glenn Research Center of a fuel cell-powered, propeller-driven, small electric airplane based on a model of the MCR 01 two-place kitplane.

Unique properties of halide perovskites as possible origins of the superior solar cell performance.

PubMed

Yin, Wan-Jian; Shi, Tingting; Yan, Yanfa

2014-07-16

Halide perovskites solar cells have the potential to exhibit higher energy conversion efficiencies with ultrathin films than conventional thin-film solar cells based on CdTe, CuInSe2 , and Cu2 ZnSnSe4 . The superior solar-cell performance of halide perovskites may originate from its high optical absorption, comparable electron and hole effective mass, and electrically clean defect properties, including point defects and grain boundaries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polybenzimidazole-membrane-based PEM fuel cell in the temperature range of 120-200 °C

NASA Astrophysics Data System (ADS)

Zhang, Jianlu; Tang, Yanghua; Song, Chaojie; Zhang, Jiujun

Phosphoric acid-doped polybenzimidazole-membrane-based PEM fuel cells were tested in the temperature range of 120-200 °C, with ambient backpressure and 0% RH. AC impedance spectroscopy, surface cyclic voltammetry and fuel cell performance simulation were used to obtain the exchange current densities for the cathodic oxygen reduction reaction (ORR) and anodic hydrogen oxidation reaction (HOR) on platinum-based catalysts at such high temperatures. The activation energies for ORR, HOR and membrane conductivity were also obtained separately. The results showed that temperature significantly affects the charger transfer and gas (O 2 and H 2) diffusion resistances. The effect of O 2 stoichiometry (ST air) on fuel cell performance was also investigated. Increasing ST air can effectively increase the O 2 partial pressure in the feed air, leading to improvements in both the thermodynamics and the kinetics of the fuel cell reactions. In addition, it was observed that increasing ST air could also improve the gas diffusion processes.

Fullerene derivatives as electron donor for organic photovoltaic cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: xf-wang@yz.yamagata-u.ac.jp, E-mail: ziruo@yz.yamagata-u.ac.jp; Sano, Takeshi

2013-11-11

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C{sub 60} bisadduct (ICBA) and phenyl C{sub 61}-butyric acid methyl ester as the electron donors with fullerene C{sub 70} as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C{sub 70} PHJ cell gives clear external quantummore » efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.« less

Power efficient, clock gated multiplexer based full adder cell using 28 nm technology

NASA Astrophysics Data System (ADS)

Gupta, Ashutosh; Murgai, Shruti; Gulati, Anmol; Kumar, Pradeep

2016-03-01

Clock gating is a leading technique used for power saving. Full adders is one of the basic circuit that can be found in maximum VLSI circuits. In this paper clock gated multiplexer based full adder cell is implemented on 28 nm technology. We have designed a full adder cell using a multiplexer with a gated clock without degrading its performance of the cell. We have negative latch circuit for generating gated clock. This gated clock is used to control the multiplexer based full adder cell. The circuit has been synthesized on kintex FPGA through Xilinx ISE Design Suite 14.7 using 28 nm technology in Verilog HDL. The circuit has been simulated on Modelsim 10.3c. The design is verified using System Verilog on QuestaSim in UVM environment. The total power of the circuit has been reduced by 7.41% without degrading the performance of original circuit. The power has been calculated using XPower Analyzer tool of XILINX ISE DESIGN SUITE 14.3.

Novel method for evaluation of natural dyes in DSSC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lakshmi, M.; Kavitha, S.; Paul, Mercyleena

Dye sensitized Solar Cell (DSSC) is presently centered on Ruthenium based dyes. Recent research is diverted to explore the potential of natural dyes in replacing the conventional dyes. In this work we have chosen few natural dyes, which when coated on TiO{sub 2} leads to increase in absorption capacity of TiO{sub 2}. Co-relation of absorption and electrochemical properties of natural dyes gives a scientific insight of the probable performance of a dye, even without fabricating a cell. We have tried to compare this predictions based on HOMO-LUMO energy levels with the real cell performance. Measurements of cell parameters suggest thatmore » there is scope for further research in this area.« less

Adaptive and automatic red blood cell counting method based on microscopic hyperspectral imaging technology

NASA Astrophysics Data System (ADS)

Liu, Xi; Zhou, Mei; Qiu, Song; Sun, Li; Liu, Hongying; Li, Qingli; Wang, Yiting

2017-12-01

Red blood cell counting, as a routine examination, plays an important role in medical diagnoses. Although automated hematology analyzers are widely used, manual microscopic examination by a hematologist or pathologist is still unavoidable, which is time-consuming and error-prone. This paper proposes a full-automatic red blood cell counting method which is based on microscopic hyperspectral imaging of blood smears and combines spatial and spectral information to achieve high precision. The acquired hyperspectral image data of the blood smear in the visible and near-infrared spectral range are firstly preprocessed, and then a quadratic blind linear unmixing algorithm is used to get endmember abundance images. Based on mathematical morphological operation and an adaptive Otsu’s method, a binaryzation process is performed on the abundance images. Finally, the connected component labeling algorithm with magnification-based parameter setting is applied to automatically select the binary images of red blood cell cytoplasm. Experimental results show that the proposed method can perform well and has potential for clinical applications.

Exploiting NanoLuc luciferase for smartphone-based bioluminescence cell biosensor for (anti)-inflammatory activity and toxicity.

PubMed

Cevenini, Luca; Calabretta, Maria Maddalena; Lopreside, Antonia; Tarantino, Giuseppe; Tassoni, Annalisa; Ferri, Maura; Roda, Aldo; Michelini, Elisa

2016-12-01

The availability of smartphones with high-performance digital image sensors and processing power has completely reshaped the landscape of point-of-need analysis. Thanks to the high maturity level of reporter gene technology and the availability of several bioluminescent proteins with improved features, we were able to develop a bioluminescence smartphone-based biosensing platform exploiting the highly sensitive NanoLuc luciferase as reporter. A 3D-printed smartphone-integrated cell biosensor based on genetically engineered Hek293T cells was developed. Quantitative assessment of (anti)-inflammatory activity and toxicity of liquid samples was performed with a simple and rapid add-and-measure procedure. White grape pomace extracts, known to contain several bioactive compounds, were analyzed, confirming the suitability of the smartphone biosensing platform for analysis of untreated complex biological matrices. Such approach could meet the needs of small medium enterprises lacking fully equipped laboratories for first-level safety tests and rapid screening of new bioactive products. Graphical abstract Smartphone-based bioluminescence cell biosensor.

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1.

PubMed

Bovo, Fernanda; Franco, Larissa Tuanny; Rosim, Roice Eliana; Barbalho, Ricardo; de Oliveira, Carlos Augusto Fernandes

2015-06-01

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B1 (AFB1) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB1/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB1 in the samples was performed by high performance liquid chromatography. AFB1 adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB1 binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB1 binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins.

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1

PubMed Central

Bovo, Fernanda; Franco, Larissa Tuanny; Rosim, Roice Eliana; Barbalho, Ricardo; de Oliveira, Carlos Augusto Fernandes

2015-01-01

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B1 (AFB1) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB1/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB1 in the samples was performed by high performance liquid chromatography. AFB1 adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB1 binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB1 binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins. PMID:26273277

Simultaneous genomic identification and profiling of a single cell using semiconductor-based next generation sequencing.

PubMed

Watanabe, Manabu; Kusano, Junko; Ohtaki, Shinsaku; Ishikura, Takashi; Katayama, Jin; Koguchi, Akira; Paumen, Michael; Hayashi, Yoshiharu

2014-09-01

Combining single-cell methods and next-generation sequencing should provide a powerful means to understand single-cell biology and obviate the effects of sample heterogeneity. Here we report a single-cell identification method and seamless cancer gene profiling using semiconductor-based massively parallel sequencing. A549 cells (adenocarcinomic human alveolar basal epithelial cell line) were used as a model. Single-cell capture was performed using laser capture microdissection (LCM) with an Arcturus® XT system, and a captured single cell and a bulk population of A549 cells (≈ 10(6) cells) were subjected to whole genome amplification (WGA). For cell identification, a multiplex PCR method (AmpliSeq™ SNP HID panel) was used to enrich 136 highly discriminatory SNPs with a genotype concordance probability of 10(31-35). For cancer gene profiling, we used mutation profiling that was performed in parallel using a hotspot panel for 50 cancer-related genes. Sequencing was performed using a semiconductor-based bench top sequencer. The distribution of sequence reads for both HID and Cancer panel amplicons was consistent across these samples. For the bulk population of cells, the percentages of sequence covered at coverage of more than 100 × were 99.04% for the HID panel and 98.83% for the Cancer panel, while for the single cell percentages of sequence covered at coverage of more than 100 × were 55.93% for the HID panel and 65.96% for the Cancer panel. Partial amplification failure or randomly distributed non-amplified regions across samples from single cells during the WGA procedures or random allele drop out probably caused these differences. However, comparative analyses showed that this method successfully discriminated a single A549 cancer cell from a bulk population of A549 cells. Thus, our approach provides a powerful means to overcome tumor sample heterogeneity when searching for somatic mutations.

Two-agent cooperative search using game models with endurance-time constraints

NASA Astrophysics Data System (ADS)

Sujit, P. B.; Ghose, Debasish

2010-07-01

In this article, the problem of two Unmanned Aerial Vehicles (UAVs) cooperatively searching an unknown region is addressed. The search region is discretized into hexagonal cells and each cell is assumed to possess an uncertainty value. The UAVs have to cooperatively search these cells taking limited endurance, sensor and communication range constraints into account. Due to limited endurance, the UAVs need to return to the base station for refuelling and also need to select a base station when multiple base stations are present. This article proposes a route planning algorithm that takes endurance time constraints into account and uses game theoretical strategies to reduce the uncertainty. The route planning algorithm selects only those cells that ensure the agent will return to any one of the available bases. A set of paths are formed using these cells which the game theoretical strategies use to select a path that yields maximum uncertainty reduction. We explore non-cooperative Nash, cooperative and security strategies from game theory to enhance the search effectiveness. Monte-Carlo simulations are carried out which show the superiority of the game theoretical strategies over greedy strategy for different look ahead step length paths. Within the game theoretical strategies, non-cooperative Nash and cooperative strategy perform similarly in an ideal case, but Nash strategy performs better than the cooperative strategy when the perceived information is different. We also propose a heuristic based on partitioning of the search space into sectors to reduce computational overhead without performance degradation.

Using Electrospinning-Based Carbon Nanofiber Webs for Methanol Crossover Control in Passive Direct Methanol Fuel Cells.

PubMed

Yuan, Wei; Fang, Guoyun; Li, Zongtao; Chen, Yonghui; Tang, Yong

2018-01-04

Methanol crossover (MCO) significantly affects the performance of a direct methanol fuel cell (DMFC). In order to reduce its effect, this study presents in-house carbon nanofiber webs (CNWs) used as a porous methanol barrier for MCO control in a passive DMFC. The CNW is made from polyacrylonitrile (PAN) by using electrospinning and heat treatment. The impacts of PAN concentration and carbonizing temperature on the material properties are considered. The concentration of PAN has a great effect on the micro structures of the CNWs since a higher concentration of PAN leads to a larger nanofiber diameter and lower porosity. A higher carbonizing temperature helps promote the sample conductivity. The use of CNWs has twofold effects on the cell performance. It helps significantly enhance the cell performance, especially at a low methanol concentration due to its balanced effect on reactant and product management. There is an increase in peak power density of up to 53.54% when the CNW is used, in contrast with the conventional DMFC at 2 mol/L. The dynamic and constant-load performances of the fuel cell based on CNWs are also investigated in this work.

Using Electrospinning-Based Carbon Nanofiber Webs for Methanol Crossover Control in Passive Direct Methanol Fuel Cells

PubMed Central

Fang, Guoyun; Chen, Yonghui; Tang, Yong

2018-01-01

Methanol crossover (MCO) significantly affects the performance of a direct methanol fuel cell (DMFC). In order to reduce its effect, this study presents in-house carbon nanofiber webs (CNWs) used as a porous methanol barrier for MCO control in a passive DMFC. The CNW is made from polyacrylonitrile (PAN) by using electrospinning and heat treatment. The impacts of PAN concentration and carbonizing temperature on the material properties are considered. The concentration of PAN has a great effect on the micro structures of the CNWs since a higher concentration of PAN leads to a larger nanofiber diameter and lower porosity. A higher carbonizing temperature helps promote the sample conductivity. The use of CNWs has twofold effects on the cell performance. It helps significantly enhance the cell performance, especially at a low methanol concentration due to its balanced effect on reactant and product management. There is an increase in peak power density of up to 53.54% when the CNW is used, in contrast with the conventional DMFC at 2 mol/L. The dynamic and constant-load performances of the fuel cell based on CNWs are also investigated in this work. PMID:29300368

Analysis and performance assessment of a new solar-based multigeneration system integrated with ammonia fuel cell and solid oxide fuel cell-gas turbine combined cycle

NASA Astrophysics Data System (ADS)

Siddiqui, Osamah; Dincer, Ibrahim

2017-12-01

In the present study, a new solar-based multigeneration system integrated with an ammonia fuel cell and solid oxide fuel cell-gas turbine combined cycle to produce electricity, hydrogen, cooling and hot water is developed for analysis and performance assessment. In this regard, thermodynamic analyses and modeling through both energy and exergy approaches are employed to assess and evaluate the overall system performance. Various parametric studies are conducted to study the effects of varying system parameters and operating conditions on the energy and exergy efficiencies. The results of this study show that the overall multigeneration system energy efficiency is obtained as 39.1% while the overall system exergy efficiency is calculated as 38.7%, respectively. The performance of this multigeneration system results in an increase of 19.3% in energy efficiency as compared to single generation system. Furthermore, the exergy efficiency of the multigeneration system is 17.8% higher than the single generation system. Moreover, both energy and exergy efficiencies of the solid oxide fuel cell-gas turbine combined cycle are determined as 68.5% and 55.9% respectively.

Parameters influencing the deposition of methylammonium lead halide iodide in hole conductor free perovskite-based solar cells

NASA Astrophysics Data System (ADS)

Cohen, Bat-El; Gamliel, Shany; Etgar, Lioz

2014-08-01

Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy. An important parameter when designing high efficiency perovskite-based solar cells is the perovskite deposition, which must be performed to create complete coverage and optimal film thickness. This paper describes an in-depth study on two-step deposition, separating the perovskite deposition into two precursors. The effects of spin velocity, annealing temperature, dipping time, and methylammonium iodide concentration on the photovoltaic performance are studied. Observations include that current density is affected by changing the spin velocity, while the fill factor changes mainly due to the dipping time and methylammonium iodide concentration. Interestingly, the open circuit voltage is almost unaffected by these parameters. Hole conductor free perovskite solar cells are used in this work, in order to minimize other possible effects. This study provides better understanding and control over the perovskite deposition through highly efficient, low-cost perovskite-based solar cells.

Entrapped cells-based-anaerobic membrane bioreactor treating domestic wastewater: Performances, fouling, and bacterial community structure.

PubMed

Juntawang, Chaipon; Rongsayamanont, Chaiwat; Khan, Eakalak

2017-11-01

A laboratory scale study on treatment performances and fouling of entrapped cells-based-anaerobic membrane bioreactor (E-AnMBR) in comparison with suspended cells-based-bioreactor (S-AnMBR) treating domestic wastewater was conducted. The difference between E-AnMBR and S-AnMBR was the uses of cells entrapped in phosphorylated polyvinyl alcohol versus planktonic cells. Bulk organic removal efficiencies by the two AnMBRs were comparable. Lower concentrations of suspended biomass, bound extracellular polymeric substances and soluble microbial products in E-AnMBR resulted in less fouling compared to S-AnMBR. S-AnMBR provided 7 days of operation time versus 11 days for E-AnMBR before chemical cleaning was required. The less frequent chemical cleaning potentially leads to a longer membrane life-span for E-AnMBR compared to S-AnMBR. Phyla Proteobacteria, Chloroflexi, Bacteroidetes and Acidobacteria were dominant in cake sludge from both AnMBRs but their abundances were different between the two AnMBRs, suggesting influence of cell entrapment on the bacteria community. Copyright © 2017 Elsevier Ltd. All rights reserved.

ASSESSMENT OF TWO PHYSICALLY-BASED WATERSHED MODELS BASED ON THEIR PERFORMANCES OF SIMULATING WATER AND SEDIMENT MOVEMENT

EPA Science Inventory

Two physically based watershed models, GSSHA and KINEROS-2 are evaluated and compared for their performances on modeling flow and sediment movement. Each model has a different watershed conceptualization. GSSHA divides the watershed into cells, and flow and sediments are routed t...

Achieving high performance polymer tandem solar cells via novel materials design

NASA Astrophysics Data System (ADS)

Dou, Letian

Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 10% enhancement over those based on PBDTT-DPP. Finally, in Chapter 5, I demonstrate a new polymer system based on alternating dithienopyran and benzothiadiazole units with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions, which is the first certified polymer solar cell efficiency over 10%.

Single-cell analysis of population context advances RNAi screening at multiple levels

PubMed Central

Snijder, Berend; Sacher, Raphael; Rämö, Pauli; Liberali, Prisca; Mench, Karin; Wolfrum, Nina; Burleigh, Laura; Scott, Cameron C; Verheije, Monique H; Mercer, Jason; Moese, Stefan; Heger, Thomas; Theusner, Kristina; Jurgeit, Andreas; Lamparter, David; Balistreri, Giuseppe; Schelhaas, Mario; De Haan, Cornelis A M; Marjomäki, Varpu; Hyypiä, Timo; Rottier, Peter J M; Sodeik, Beate; Marsh, Mark; Gruenberg, Jean; Amara, Ali; Greber, Urs; Helenius, Ari; Pelkmans, Lucas

2012-01-01

Isogenic cells in culture show strong variability, which arises from dynamic adaptations to the microenvironment of individual cells. Here we study the influence of the cell population context, which determines a single cell's microenvironment, in image-based RNAi screens. We developed a comprehensive computational approach that employs Bayesian and multivariate methods at the single-cell level. We applied these methods to 45 RNA interference screens of various sizes, including 7 druggable genome and 2 genome-wide screens, analysing 17 different mammalian virus infections and four related cell physiological processes. Analysing cell-based screens at this depth reveals widespread RNAi-induced changes in the population context of individual cells leading to indirect RNAi effects, as well as perturbations of cell-to-cell variability regulators. We find that accounting for indirect effects improves the consistency between siRNAs targeted against the same gene, and between replicate RNAi screens performed in different cell lines, in different labs, and with different siRNA libraries. In an era where large-scale RNAi screens are increasingly performed to reach a systems-level understanding of cellular processes, we show that this is often improved by analyses that account for and incorporate the single-cell microenvironment. PMID:22531119

Advantages of thin silicon solar cells for use in space

NASA Technical Reports Server (NTRS)

Denman, O. S.

1978-01-01

A system definition study on the Solar Power Satellite System showed that a thin, 50 micrometers, silicon solar cell has significant advantages. The advantages include a significantly lower performance degradation in a radiation environment and high power-to-mass ratios. The advantages of such cells for an employment in space is further investigated. Basic questions concerning the operation of solar cells are considered along with aspects of radiation induced performance degradation. The question arose in this connection how thin a silicon solar cell had to be to achieve resistance to radiation degradation and still have good initial performance. It was found that single-crystal silicon solar cells could be as thin as 50 micrometers and still develop high conversion efficiencies. It is concluded that the use of 50 micrometer silicon solar cells in space-based photovoltaic power systems would be advantageous.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

NASA Astrophysics Data System (ADS)

Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agricola, J.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Verzini, M. J. Alconada; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Gonzalez, B. Alvarez; Piqueras, D. Álvarez; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Coutinho, Y. Amaral; Amelung, C.; Amidei, D.; Santos, S. P. Amor Dos; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Bella, L. Aperio; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bacci, C.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bain, T.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; da Costa, J. Barreiro Guimarães; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Basye, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Noccioli, E. Benhar; Garcia, J. A. Benitez; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Kuutmann, E. Bergeaas; Berger, N.; Berghaus, F.; Beringer, J.; Bernard, C.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertsche, C.; Bertsche, D.; Besana, M. I.; Besjes, G. J.; Bylund, O. Bessidskaia; Bessner, M.; Besson, N.; Betancourt, C.; Bethke, S.; Bevan, A. J.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Biedermann, D.; Biesuz, N. V.; Biglietti, M.; De Mendizabal, J. Bilbao; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blanco, J. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. 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K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burghgrave, B.; Burke, S.; Burmeister, I.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Butt, A. I.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Urbán, S. Cabrera; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Caloba, L. P.; Calvet, D.; Calvet, S.; Toro, R. Camacho; Camarda, S.; Camarri, P.; Cameron, D.; Armadans, R. Caminal; Campana, S.; Campanelli, M.; Campoverde, A.; Canale, V.; Canepa, A.; Bret, M. Cano; Cantero, J.; Cantrill, R.; Cao, T.; Garrido, M. D. M. Capeans; Caprini, I.; Caprini, M.; Capua, M.; Caputo, R.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, T.; Carlino, G.; Carminati, L.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castaneda-Miranda, E.; Castelli, A.; Gimenez, V. Castillo; Castro, N. F.; Catastini, P.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Alberich, L. Cerda; Cerio, B. C.; Cerny, K.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chalupkova, I.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Barajas, C. A. Chavez; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, L.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Moursli, R. Cherkaoui El; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chislett, R. T.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Coffey, L.; Cogan, J. G.; Colasurdo, L.; Cole, B.; Cole, S.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Muiño, P. Conde; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consorti, V.; Constantinescu, S.; Conta, C.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Corso-Radu, A.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Côté, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Ortuzar, M. Crispin; Cristinziani, M.; Croft, V.; Crosetti, G.; Donszelmann, T. Cuhadar; Cummings, J.; Curatolo, M.; Cúth, J.; Cuthbert, C.; Czirr, H.; Czodrowski, P.; D'Auria, S.; D'Onofrio, M.; De Sousa, M. J. Da Cunha Sargedas; Via, C. Da; Dabrowski, W.; Dafinca, A.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Dang, N. P.; Daniells, A. C.; Danninger, M.; Hoffmann, M. Dano; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Davey, W.; David, C.; Davidek, T.; Davies, E.; Davies, M.; Davison, P.; Davygora, Y.; Dawe, E.; Dawson, I.; Daya-Ishmukhametova, R. K.; De, K.; de Asmundis, R.; De Benedetti, A.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Regie, J. B. De Vivie; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Deigaard, I.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Deliyergiyev, M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delsart, P. A.; Deluca, C.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Ciaccio, A.; Di Ciaccio, L.; Di Domenico, A.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Mattia, A.; Di Micco, B.; Di Nardo, R.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Diglio, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dohmae, T.; Dolejsi, J.; Dolezal, Z.; Dolgoshein, B. A.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Dubreuil, E.; Duchovni, E.; Duckeck, G.; Ducu, O. A.; Duda, D.; Dudarev, A.; Duflot, L.; Duguid, L.; Dührssen, M.; Dunford, M.; Yildiz, H. Duran; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Dyndal, M.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Edson, W.; Edwards, N. C.; Ehrenfeld, W.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; Kacimi, M. El; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Endo, M.; Erdmann, J.; Ereditato, A.; Ernis, G.; Ernst, J.; Ernst, M.; Errede, S.; Ertel, E.; Escalier, M.; Esch, H.; Escobar, C.; Esposito, B.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Giannelli, M. Faucci; Favareto, A.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenyuk, A. B.; Feremenga, L.; Martinez, P. Fernandez; Perez, S. Fernandez; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; de Lima, D. E. Ferreira; Ferrer, A.; Ferrere, D.; Ferretti, C.; Parodi, A. Ferretto; Fiascaris, M.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Firan, A.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, G. T.; Fletcher, G.; Fletcher, R. R. M.; Flick, T.; Floderus, A.; Castillo, L. R. Flores; Flowerdew, M. J.; Formica, A.; Forti, A.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; French, S. T.; Fressard-Batraneanu, S. M.; Friedrich, F.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Torregrosa, E. Fullana; Fulsom, B. G.; Fusayasu, T.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gach, G. P.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, P.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Gao, J.; Gao, Y.; Gao, Y. S.; Walls, F. M. Garay; Garberson, F.; García, C.; Navarro, J. E. García; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gatti, C.; Gaudiello, A.; Gaudio, G.; Gaur, B.; Gauthier, L.; Gauzzi, P.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Ge, P.; Gecse, Z.; Gee, C. N. P.; Geich-Gimbel, Ch.; Geisler, M. P.; Gemme, C.; Genest, M. H.; Geng, C.; Gentile, S.; George, M.; George, S.; Gerbaudo, D.; Gershon, A.; Ghasemi, S.; Ghazlane, H.; Giacobbe, B.; Giagu, S.; Giangiobbe, V.; Giannetti, P.; Gibbard, B.; Gibson, S. M.; Gignac, M.; Gilchriese, M.; Gillam, T. P. S.; Gillberg, D.; Gilles, G.; Gingrich, D. M.; Giokaris, N.; Giordani, M. P.; Giorgi, F. M.; Giorgi, F. M.; Giraud, P. F.; Giromini, P.; Giugni, D.; Giuliani, C.; Giulini, M.; Gjelsten, B. K.; Gkaitatzis, S.; Gkialas, I.; Gkougkousis, E. L.; Gladilin, L. K.; Glasman, C.; Glatzer, J.; Glaysher, P. C. F.; Glazov, A.; Goblirsch-Kolb, M.; Goddard, J. R.; Godlewski, J.; Goldfarb, S.; Golling, T.; Golubkov, D.; Gomes, A.; Gonçalo, R.; Costa, J. Goncalves Pinto Firmino Da; Gonella, L.; de la Hoz, S. González; Parra, G. Gonzalez; Gonzalez-Sevilla, S.; Goossens, L.; Gorbounov, P. A.; Gordon, H. A.; Gorelov, I.; Gorini, B.; Gorini, E.; Gorišek, A.; Gornicki, E.; Goshaw, A. T.; Gössling, C.; Gostkin, M. I.; Goujdami, D.; Goussiou, A. G.; Govender, N.; Gozani, E.; Grabas, H. M. X.; Graber, L.; Grabowska-Bold, I.; Gradin, P. O. J.; Grafström, P.; Gramling, J.; Gramstad, E.; Grancagnolo, S.; Gratchev, V.; Gray, H. M.; Graziani, E.; Greenwood, Z. D.; Grefe, C.; Gregersen, K.; Gregor, I. M.; Grenier, P.; Griffiths, J.; Grillo, A. A.; Grimm, K.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groh, S.; Grohs, J. 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J.; Hostachy, J.-Y.; Hou, S.; Hoummada, A.; Howard, J.; Howarth, J.; Hrabovsky, M.; Hristova, I.; Hrivnac, J.; Hryn'ova, T.; Hrynevich, A.; Hsu, C.; Hsu, P. J.; Hsu, S.-C.; Hu, D.; Hu, Q.; Hu, X.; Huang, Y.; Hubacek, Z.; Hubaut, F.; Huegging, F.; Huffman, T. B.; Hughes, E. W.; Hughes, G.; Huhtinen, M.; Hülsing, T. A.; Huseynov, N.; Huston, J.; Huth, J.; Iacobucci, G.; Iakovidis, G.; Ibragimov, I.; Iconomidou-Fayard, L.; Ideal, E.; Idrissi, Z.; Iengo, P.; Igonkina, O.; Iizawa, T.; Ikegami, Y.; Ikeno, M.; Ilchenko, Y.; Iliadis, D.; Ilic, N.; Ince, T.; Introzzi, G.; Ioannou, P.; Iodice, M.; Iordanidou, K.; Ippolito, V.; Quiles, A. Irles; Isaksson, C.; Ishino, M.; Ishitsuka, M.; Ishmukhametov, R.; Issever, C.; Istin, S.; Ponce, J. M. Iturbe; Iuppa, R.; Ivarsson, J.; Iwanski, W.; Iwasaki, H.; Izen, J. M.; Izzo, V.; Jabbar, S.; Jackson, B.; Jackson, M.; Jackson, P.; Jaekel, M. R.; Jain, V.; Jakobi, K. B.; Jakobs, K.; Jakobsen, S.; Jakoubek, T.; Jakubek, J.; Jamin, D. O.; Jana, D. 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2017-07-01

The reconstruction of the signal from hadrons and jets emerging from the proton-proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1.

PubMed

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2017-01-01

The reconstruction of the signal from hadrons and jets emerging from the proton-proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aad, G.; Abbott, B.; Abdallah, J.

The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections dependingmore » on the nature of the cluster. Lastly, topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.« less

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2017-07-24

The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections dependingmore » on the nature of the cluster. Lastly, topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.« less

An Image-Based Algorithm for Precise and Accurate High Throughput Assessment of Drug Activity against the Human Parasite Trypanosoma cruzi

PubMed Central

Moraes, Carolina Borsoi; Yang, Gyongseon; Kang, Myungjoo; Freitas-Junior, Lucio H.; Hansen, Michael A. E.

2014-01-01

We present a customized high content (image-based) and high throughput screening algorithm for the quantification of Trypanosoma cruzi infection in host cells. Based solely on DNA staining and single-channel images, the algorithm precisely segments and identifies the nuclei and cytoplasm of mammalian host cells as well as the intracellular parasites infecting the cells. The algorithm outputs statistical parameters including the total number of cells, number of infected cells and the total number of parasites per image, the average number of parasites per infected cell, and the infection ratio (defined as the number of infected cells divided by the total number of cells). Accurate and precise estimation of these parameters allow for both quantification of compound activity against parasites, as well as the compound cytotoxicity, thus eliminating the need for an additional toxicity-assay, hereby reducing screening costs significantly. We validate the performance of the algorithm using two known drugs against T.cruzi: Benznidazole and Nifurtimox. Also, we have checked the performance of the cell detection with manual inspection of the images. Finally, from the titration of the two compounds, we confirm that the algorithm provides the expected half maximal effective concentration (EC50) of the anti-T. cruzi activity. PMID:24503652

Development and fabrication of large vented nickel--zinc cells. Final report. [300 Ah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donnel, C.P.I.

1975-12-01

A preliminary cell design for a 300-Ah vented nickel--zinc cell was established based on volume requirements and cell component materials selected by NASA Lewis Research Center. A 100-Ah cell configuration was derived from the 300-Ah cell design utilizing the same size electrodes, separators, and cell terminal hardware. The first cells fabricated were four groups of three cells each in the 100-Ah size. These 100-Ah experimental nickel--zinc cells had as common components the nickel positive electrodes (GFM), flexible inorganic separator (GFM) bags on the negative electrodes, pressed powder zinc oxide electrodes, and cell containers with hardware. The variations introduced were fourmore » differing electrolyte absorber (interseparator) systems used to encase the nickel positive electrodes of each cell group. The four groups of 100-Ah experimental vented nickel--zinc cells were tested to determine, based on cell performance, the best two interseparator systems. Using the two interseparator systems, two groups of experimental 300-AH cells were fabricated. Each group of three cells differed only in the interseparator material used. The six cells were filled, formed and tested to evaluate the interseparator materials and investigate the performance characteristics of the 300-Ah cell configuration and its components. (auth)« less

To probe the equivalence and opulence of nanocrystal and nanotube based dye-sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jyoti, Divya, E-mail: divyabathla17@gmail.com; Mohan, Devendra

2016-05-06

Dye-Sensitized solar cells based on TiO{sub 2} nanocrystal and TiO{sub 2} nanotubes have been fabricated by a simple sol-gel hydrothermal process and their performances have been compared. Current density and voltage (JV) characteristics and incident photon to current conversion efficiency (IPCE) plots have been set as criterion to check which one is better as a photoanode candidate in dye-sensitized solar cell. It has been observed that although open circuit voltage values for both type of cells do not differ much still, nanotube based dye-sensitized solar cells are more successful having an efficiency value of 7.28%.

Microwave magnetic field detection based on Cs vapor cell in free space

NASA Astrophysics Data System (ADS)

Liu, Xiaochi; Jiang, Zhiyuan; Qu, Jifeng; Hou, Dong; Huang, Xianhe; Sun, Fuyu

2018-06-01

In this study, we demonstrate the direct measurement of a microwave (MW) magnetic field through the detection of atomic Rabi resonances with Cs vapor cells in a free-space low-Q cavity. The line shape (amplitude and linewidth) of detected Rabi resonances is investigated versus several experimental parameters such as the laser intensity, cell buffer gas pressure, and cell length. The specially designed low-Q cavity creates a suitable MW environment allowing easy testing of different vapor cells with distinct properties. Obtained results are analyzed to optimize the performances of a MW magnetic field sensor based on the present atom-based detection technique.

Thermodynamic analysis of biofuels as fuels for high temperature fuel cells

NASA Astrophysics Data System (ADS)

Milewski, Jarosław; Bujalski, Wojciech; Lewandowski, Janusz

2011-11-01

Based on mathematical modeling and numerical simulations, applicativity of various biofuels on high temperature fuel cell performance are presented. Governing equations of high temperature fuel cell modeling are given. Adequate simulators of both solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) have been done and described. Performance of these fuel cells with different biofuels is shown. Some characteristics are given and described. Advantages and disadvantages of various biofuels from the system performance point of view are pointed out. An analysis of various biofuels as potential fuels for SOFC and MCFC is presented. The results are compared with both methane and hydrogen as the reference fuels. The biofuels are characterized by both lower efficiency and lower fuel utilization factors compared with methane. The presented results are based on a 0D mathematical model in the design point calculation. The governing equations of the model are also presented. Technical and financial analysis of high temperature fuel cells (SOFC and MCFC) are shown. High temperature fuel cells can be fed by biofuels like: biogas, bioethanol, and biomethanol. Operational costs and possible incomes of those installation types were estimated and analyzed. A comparison against classic power generation units is shown. A basic indicator net present value (NPV) for projects was estimated and commented.

Thermodynamic analysis of biofuels as fuels for high temperature fuel cells

NASA Astrophysics Data System (ADS)

Milewski, Jarosław; Bujalski, Wojciech; Lewandowski, Janusz

2013-02-01

Based on mathematical modeling and numerical simulations, applicativity of various biofuels on high temperature fuel cell performance are presented. Governing equations of high temperature fuel cell modeling are given. Adequate simulators of both solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) have been done and described. Performance of these fuel cells with different biofuels is shown. Some characteristics are given and described. Advantages and disadvantages of various biofuels from the system performance point of view are pointed out. An analysis of various biofuels as potential fuels for SOFC and MCFC is presented. The results are compared with both methane and hydrogen as the reference fuels. The biofuels are characterized by both lower efficiency and lower fuel utilization factors compared with methane. The presented results are based on a 0D mathematical model in the design point calculation. The governing equations of the model are also presented. Technical and financial analysis of high temperature fuel cells (SOFC and MCFC) are shown. High temperature fuel cells can be fed by biofuels like: biogas, bioethanol, and biomethanol. Operational costs and possible incomes of those installation types were estimated and analyzed. A comparison against classic power generation units is shown. A basic indicator net present value (NPV) for projects was estimated and commented.

Infiltrated La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3 based anodes for all ceramic and metal supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Nielsen, Jimmi; Persson, Åsa H.; Sudireddy, Bhaskar R.; Irvine, John T. S.; Thydén, Karl

2017-12-01

For improved robustness, durability and to avoid severe processing challenges alternatives to the Ni:YSZ composite electrode is highly desirable. The Ni:YSZ composite electrode is conventionally used for solid oxide fuel cell and solid oxide electrolysis cell. In the present study we report on high performing nanostructured Ni:CGO electrocatalyst coated A site deficient Lanthanum doped Strontium Titanate (La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3) based anodes. The anodes were incorporated into the co-sintered DTU metal supported solid oxide fuel cell design and large sized 12 cm × 12 cm cells were fabricated. The titanate material showed good processing characteristics and surface wetting properties towards the Ni:CGO electrocatalyst coating. The cell performances were evaluated on single cell level (active area 16 cm2) and a power density at 0.7 V and 700 °C of 0.650 Wcm-2 with a fuel utilization of 31% was achieved. Taking the temperature into account the performances of the studied anodes are among the best reported for redox stable and corrosion resistant alternatives to the conventional Ni:YSZ composite solid oxide cell electrode.

Wide-Band Circularly Polarized ReflectarrayUsing Graphene-Based Pancharatnam-Berry Phase Unit-Cells for Terahertz Communication.

PubMed

Deng, Li; Zhang, Yuanyuan; Zhu, Jianfeng; Zhang, Chen

2018-06-05

A wide-band and high gain circularly polarized (CP) graphene-based reflectarray operating in the THz regime is proposed and theoretically investigated in this paper. The proposed reflectarray consists of a THz CP source and several graphene-based unit-cells. Taking advantages of the Pancharatnam Berry (PB) phase principle, the graphene-based unit-cell is capable of realizing a tunable phase range of 360° in a wide-band (1.4⁻1.7 THz) by unit-cell rotating, overcoming the restriction of intrinsic narrow-band resonance in graphene. Therefore, this graphene-based unit-cell exhibits superior bandwidth and phase tunability to its previous counterparts. To demonstrate this, a wide-band (1.4⁻1.7 THz) focusing metasurface based on the proposed unit-cell that exhibits excellent focusing effect was designed. Then, according to the reversibility of the optical path, a CP reflectarray was realized by placing a wide-band CP THz source at the focal point of the metasurface. Numerical simulation demonstrates that this reflectarray can achieve a stable high gain up to 15 dBic and an axial ratio around 2.1 dB over the 1.4⁻1.7 THz band. The good radiation performance of the proposed CP reflectarray, as demonstrated, underlines its suitability for the THz communication applications. Moreover, the design principle of this graphene-based reflectarray with a full 360° phase range tunable unit-cells provides a new pathway to design high-performance CP reflectarray in the THz regime.

Toward High Performance Photovoltaic Cells based on Conjugated Polymers

DTIC Science & Technology

2016-12-26

AFRL-AFOSR-JP-TR-2016-0103 Toward High Performance Photovoltaic Cells based on Conjugated Polymers Kung-Hwa Wei National Chiao Tung University Final...Conjugated Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4113 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Kung-Hwa Wei 5d.  PROJECT...gap polymer with good packing order as the active layer for a single-junction photovoltaic device. The light absorptions for the small molecule and the

A cell cycle-independent, conditional gene inactivation strategy for differentially tagging wild-type and mutant cells.

PubMed

Nagarkar-Jaiswal, Sonal; Manivannan, Sathiya N; Zuo, Zhongyuan; Bellen, Hugo J

2017-05-31

Here, we describe a novel method based on intronic MiMIC insertions described in Nagarkar-Jaiswal et al. (2015) to perform conditional gene inactivation in Drosophila . Mosaic analysis in Drosophila cannot be easily performed in post-mitotic cells. We therefore, therefore, developed Flip-Flop, a flippase -dependent in vivo cassette-inversion method that marks wild-type cells with the endogenous EGFP-tagged protein, whereas mutant cells are marked with mCherry upon inversion. We document the ease and usefulness of this strategy in differential tagging of wild-type and mutant cells in mosaics. We use this approach to phenotypically characterize the loss of SNF4Aγ , encoding the γ subunit of the AMP Kinase complex. The Flip-Flop method is efficient and reliable, and permits conditional gene inactivation based on both spatial and temporal cues, in a cell cycle-, and developmental stage-independent fashion, creating a platform for systematic screens of gene function in developing and adult flies with unprecedented detail.

Automated classification of cell morphology by coherence-controlled holographic microscopy

NASA Astrophysics Data System (ADS)

Strbkova, Lenka; Zicha, Daniel; Vesely, Pavel; Chmelik, Radim

2017-08-01

In the last few years, classification of cells by machine learning has become frequently used in biology. However, most of the approaches are based on morphometric (MO) features, which are not quantitative in terms of cell mass. This may result in poor classification accuracy. Here, we study the potential contribution of coherence-controlled holographic microscopy enabling quantitative phase imaging for the classification of cell morphologies. We compare our approach with the commonly used method based on MO features. We tested both classification approaches in an experiment with nutritionally deprived cancer tissue cells, while employing several supervised machine learning algorithms. Most of the classifiers provided higher performance when quantitative phase features were employed. Based on the results, it can be concluded that the quantitative phase features played an important role in improving the performance of the classification. The methodology could be valuable help in refining the monitoring of live cells in an automated fashion. We believe that coherence-controlled holographic microscopy, as a tool for quantitative phase imaging, offers all preconditions for the accurate automated analysis of live cell behavior while enabling noninvasive label-free imaging with sufficient contrast and high-spatiotemporal phase sensitivity.

Automated classification of cell morphology by coherence-controlled holographic microscopy.

PubMed

Strbkova, Lenka; Zicha, Daniel; Vesely, Pavel; Chmelik, Radim

2017-08-01

In the last few years, classification of cells by machine learning has become frequently used in biology. However, most of the approaches are based on morphometric (MO) features, which are not quantitative in terms of cell mass. This may result in poor classification accuracy. Here, we study the potential contribution of coherence-controlled holographic microscopy enabling quantitative phase imaging for the classification of cell morphologies. We compare our approach with the commonly used method based on MO features. We tested both classification approaches in an experiment with nutritionally deprived cancer tissue cells, while employing several supervised machine learning algorithms. Most of the classifiers provided higher performance when quantitative phase features were employed. Based on the results, it can be concluded that the quantitative phase features played an important role in improving the performance of the classification. The methodology could be valuable help in refining the monitoring of live cells in an automated fashion. We believe that coherence-controlled holographic microscopy, as a tool for quantitative phase imaging, offers all preconditions for the accurate automated analysis of live cell behavior while enabling noninvasive label-free imaging with sufficient contrast and high-spatiotemporal phase sensitivity. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

The donor-supply electrode enhances performance in colloidal quantum dot solar cells.

PubMed

Maraghechi, Pouya; Labelle, André J; Kirmani, Ahmad R; Lan, Xinzheng; Adachi, Michael M; Thon, Susanna M; Hoogland, Sjoerd; Lee, Anna; Ning, Zhijun; Fischer, Armin; Amassian, Aram; Sargent, Edward H

2013-07-23

Colloidal quantum dot (CQD) solar cells combine solution-processability with quantum-size-effect tunability for low-cost harvesting of the sun's broad visible and infrared spectrum. The highest-performing colloidal quantum dot solar cells have, to date, relied on a depleted-heterojunction architecture in which an n-type transparent metal oxide such as TiO2 induces a depletion region in the p-type CQD solid. These devices have, until now, been limited by a modest depletion region depth produced in the CQD solid owing to limitations in the doping available in TiO2. Herein we report a new device geometry-one based on a donor-supply electrode (DSE)-that leads to record-performing CQD photovoltaic devices. Only by employing this new charge-extracting approach do we deepen the depletion region in the CQD solid and thereby extract notably more photocarriers, the key element in achieving record photocurrent and device performance. With the use of optoelectronic modeling corroborated by experiment, we develop the guidelines for building a superior CQD solar cell based on the DSE concept. We confirm that using a shallow-work-function terminal electrode is essential to producing improved charge extraction and enhanced performance.

Aqueous-Processed Inorganic Thin-Film Solar Cells Based on CdSe(x)Te(1-x) Nanocrystals: The Impact of Composition on Photovoltaic Performance.

PubMed

Zeng, Qingsen; Chen, Zhaolai; Zhao, Yue; Du, Xiaohang; Liu, Fangyuan; Jin, Gan; Dong, Fengxia; Zhang, Hao; Yang, Bai

2015-10-21

Aqueous processed nanocrystal (NC) solar cells are attractive due to their environmental friendliness and cost effectiveness. Controlling the bandgap of absorbing layers is critical for achieving high efficiency for single and multijunction solar cells. Herein, we tune the bandgap of CdTe through the incorporation of Se via aqueous process. The photovoltaic performance of aqueous CdSexTe1-x NCs is systematically investigated, and the impacts of charge generation, transport, and injection on device performance for different compositions are deeply discussed. We discover that the performance degrades with the increasing Se content from CdTe to CdSe. This is mainly ascribed to the lower conduction band (CB) of CdSexTe1-x with higher Se content, which reduces the driving force for electron injection into TiO2. Finally, the performance is improved by mixing CdSexTe1-x NCs with conjugated polymer poly(p-phenylenevinylene) (PPV), and power conversion efficiency (PCE) of 3.35% is achieved based on ternary NCs. This work may provide some information to further optimize the aqueous-processed NC and hybrid solar cells.

The use of real-time cell analyzer technology in drug discovery: defining optimal cell culture conditions and assay reproducibility with different adherent cellular models.

PubMed

Atienzar, Franck A; Tilmant, Karen; Gerets, Helga H; Toussaint, Gaelle; Speeckaert, Sebastien; Hanon, Etienne; Depelchin, Olympe; Dhalluin, Stephane

2011-07-01

The use of impedance-based label-free technology applied to drug discovery is nowadays receiving more and more attention. Indeed, such a simple and noninvasive assay that interferes minimally with cell morphology and function allows one to perform kinetic measurements and to obtain information on proliferation, migration, cytotoxicity, and receptor-mediated signaling. The objective of the study was to further assess the usefulness of a real-time cell analyzer (RTCA) platform based on impedance in the context of quality control and data reproducibility. The data indicate that this technology is useful to determine the best coating and cellular density conditions for different adherent cellular models including hepatocytes, cardiomyocytes, fibroblasts, and hybrid neuroblastoma/neuronal cells. Based on 31 independent experiments, the reproducibility of cell index data generated from HepG2 cells exposed to DMSO and to Triton X-100 was satisfactory, with a coefficient of variation close to 10%. Cell index data were also well reproduced when cardiomyocytes and fibroblasts were exposed to 21 compounds three times (correlation >0.91, p < 0.0001). The data also show that a cell index decrease is not always associated with cytotoxicity effects and that there are some confounding factors that can affect the analysis. Finally, another drawback is that the correlation analysis between cellular impedance measurements and classical toxicity endpoints has been performed on a limited number of compounds. Overall, despite some limitations, the RTCA technology appears to be a powerful and reliable tool in drug discovery because of the reasonable throughput, rapid and efficient performance, technical optimization, and cell quality control.

Improving polymer/nanocrystal hybrid solar cell performance via tuning ligand orientation at CdSe quantum dot surface.

PubMed

Fu, Weifei; Wang, Ling; Zhang, Yanfang; Ma, Ruisong; Zuo, Lijian; Mai, Jiangquan; Lau, Tsz-Ki; Du, Shixuan; Lu, Xinhui; Shi, Minmin; Li, Hanying; Chen, Hongzheng

2014-11-12

Achieving superior solar cell performance based on the colloidal nanocrystals remains challenging due to their complex surface composition. Much attention has been devoted to the development of effective surface modification strategies to enhance electronic coupling between the nanocrystals to promote charge carrier transport. Herein, we aim to attach benzenedithiol ligands onto the surface of CdSe nanocrystals in the "face-on" geometry to minimize the nanocrystal-nanocrystal or polymer-nanocrystal distance. Furthermore, the "electroactive" π-orbitals of the benzenedithiol are expected to further enhance the electronic coupling, which facilitates charge carrier dissociation and transport. The electron mobility of CdSe QD films was improved 20 times by tuning the ligand orientation, and high performance poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT):CdSe nanocrystal hybrid solar cells were also achieved, showing a highest power conversion efficiency of 4.18%. This research could open up a new pathway to improve further the performance of colloidal nanocrystal based solar cells.

Enhanced photovoltaic performance of dye-sensitized solar cells based on NaYF4:Yb(3+), Er(3+)-incorporated nanocrystalline TiO2 electrodes.

PubMed

Zhu, Guang; Wang, Hongyan; Zhang, Quanxin; Zhang, Li

2015-08-01

Near infrared to visible up-conversion of light by rare earth ion-doped phosphors (NaYF4:Yb(3+), Er(3+)) that convert multiple photons of lower energy to higher energy photons offer new possibilities for improved performance of photovoltaic devices. Here, up-conversion phosphor NaYF4:Yb(3+), Er(3+) doped nanocrystalline TiO2 films are designed and used as a electrode for dye-sensitized solar cells, and the photovoltaic performance of DSSCs based on composite electrodes are investigated. The results show the cell with NaYF4:Yb(3+), Er(3+) achieves a power conversion efficiency of 7.65% under one sun illumination (AM 1.5G, 100mWcm(-2)), which is an increase of 14% compared to the cell without NaYF4:Yb(3+), Er(3+) (6.71%). The performance improvement is attributed to the dual effects of enhanced light harvesting from extended light absorption range and increased light scattering, and lower electron transfer resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

2016-10-01

Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

A-π-D-π-A Electron-Donating Small Molecules for Solution-Processed Organic Solar Cells: A Review.

PubMed

Wang, Zhen; Zhu, Lingyun; Shuai, Zhigang; Wei, Zhixiang

2017-11-01

Organic solar cells based on semiconducting polymers and small molecules have attracted considerable attention in the last two decades. Moreover, the power conversion efficiencies for solution-processed solar cells containing A-π-D-π-A-type small molecules and fullerenes have reached 11%. However, the method for designing high-performance, photovoltaic small molecules still remains unclear. In this review, recent studies on A-π-D-π-A electron-donating small molecules for organic solar cells are introduced. Moreover, the relationships between molecular properties and device performances are summarized, from which inspiration for the future design of high performance organic solar cells may be obtained. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A power pack based on organometallic perovskite solar cell and supercapacitor.

PubMed

Xu, Xiaobao; Li, Shaohui; Zhang, Hua; Shen, Yan; Zakeeruddin, Shaik M; Graetzel, Michael; Cheng, Yi-Bing; Wang, Mingkui

2015-02-24

We present an investigation on a power pack combining a CH3NH3PbI3-based solar cell with a polypyrrole-based supercapacitor and evaluate its performance as an energy pack. The package achieved an energy storage efficiency of 10%, which is much higher than that of other systems combining a PV cell with a supercapacitor. We find a high output voltage of 1.45 V for the device under AM 1.5G illumination when the CH3NH3PbI3-based solar cell is connected in series with a polypyrrole-based supercapacitor. This system affords continuous output of electric power by using CH3NH3PbI3-based solar cell as an energy source mitigating transients caused by light intensity fluctuations or the diurnal cycle.

Novel crosslinked membranes based on sulfonated poly(ether ether ketone) for direct methanol fuel cells.

PubMed

Zhu, Yuanqin; Zieren, Shelley; Manthiram, Arumugam

2011-07-14

Novel covalently crosslinked membranes based on sulfonated poly(ether ether ketone) and carboxylated polysulfone exhibit much lower methanol crossover and better performance in direct methanol fuel cells at 65 °C in 1 and 2 M methanol solutions compared to Nafion 115 membranes.

Bioreactor design for successive culture of anchorage-dependent cells operated in an automated manner.

PubMed

Kino-Oka, Masahiro; Ogawa, Natsuki; Umegaki, Ryota; Taya, Masahito

2005-01-01

A novel bioreactor system was designed to perform a series of batchwise cultures of anchorage-dependent cells by means of automated operations of medium change and passage for cell transfer. The experimental data on contamination frequency ensured the biological cleanliness in the bioreactor system, which facilitated the operations in a closed environment, as compared with that in flask culture system with manual handlings. In addition, the tools for growth prediction (based on growth kinetics) and real-time growth monitoring by measurement of medium components (based on small-volume analyzing machinery) were installed into the bioreactor system to schedule the operations of medium change and passage and to confirm that culture proceeds as scheduled, respectively. The successive culture of anchorage-dependent cells was conducted with the bioreactor running in an automated way. The automated bioreactor gave a successful culture performance with fair accordance to preset scheduling based on the information in the latest subculture, realizing 79- fold cell expansion for 169 h. In addition, the correlation factor between experimental data and scheduled values through the bioreactor performance was 0.998. It was concluded that the proposed bioreactor with the integration of the prediction and monitoring tools could offer a feasible system for the manufacturing process of cultured tissue products.

Vector-based navigation using grid-like representations in artificial agents.

PubMed

Banino, Andrea; Barry, Caswell; Uria, Benigno; Blundell, Charles; Lillicrap, Timothy; Mirowski, Piotr; Pritzel, Alexander; Chadwick, Martin J; Degris, Thomas; Modayil, Joseph; Wayne, Greg; Soyer, Hubert; Viola, Fabio; Zhang, Brian; Goroshin, Ross; Rabinowitz, Neil; Pascanu, Razvan; Beattie, Charlie; Petersen, Stig; Sadik, Amir; Gaffney, Stephen; King, Helen; Kavukcuoglu, Koray; Hassabis, Demis; Hadsell, Raia; Kumaran, Dharshan

2018-05-01

Deep neural networks have achieved impressive successes in fields ranging from object recognition to complex games such as Go 1,2 . Navigation, however, remains a substantial challenge for artificial agents, with deep neural networks trained by reinforcement learning 3-5 failing to rival the proficiency of mammalian spatial behaviour, which is underpinned by grid cells in the entorhinal cortex 6 . Grid cells are thought to provide a multi-scale periodic representation that functions as a metric for coding space 7,8 and is critical for integrating self-motion (path integration) 6,7,9 and planning direct trajectories to goals (vector-based navigation) 7,10,11 . Here we set out to leverage the computational functions of grid cells to develop a deep reinforcement learning agent with mammal-like navigational abilities. We first trained a recurrent network to perform path integration, leading to the emergence of representations resembling grid cells, as well as other entorhinal cell types 12 . We then showed that this representation provided an effective basis for an agent to locate goals in challenging, unfamiliar, and changeable environments-optimizing the primary objective of navigation through deep reinforcement learning. The performance of agents endowed with grid-like representations surpassed that of an expert human and comparison agents, with the metric quantities necessary for vector-based navigation derived from grid-like units within the network. Furthermore, grid-like representations enabled agents to conduct shortcut behaviours reminiscent of those performed by mammals. Our findings show that emergent grid-like representations furnish agents with a Euclidean spatial metric and associated vector operations, providing a foundation for proficient navigation. As such, our results support neuroscientific theories that see grid cells as critical for vector-based navigation 7,10,11 , demonstrating that the latter can be combined with path-based strategies to support navigation in challenging environments.

Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

2012-01-01

Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

New insights into non-precious metal catalyst layer designs for proton exchange membrane fuel cells: Improving performance and stability

NASA Astrophysics Data System (ADS)

Banham, Dustin; Kishimoto, Takeaki; Sato, Tetsutaro; Kobayashi, Yoshikazu; Narizuka, Kumi; Ozaki, Jun-ichi; Zhou, Yingjie; Marquez, Emil; Bai, Kyoung; Ye, Siyu

2017-03-01

The activity of non-precious metal catalysts (NPMCs) has now reached a stage at which they can be considered as possible alternatives to Pt for some proton exchange membrane fuel cell (PEMFC) applications. However, despite significant efforts over the past 50 years on catalyst development, only limited studies have been performed on NPMC-based cathode catalyst layer (CCL) designs. In this work, an extensive ionomer study is performed to investigate the impact of ionomer equivalent weight on performance, which has uncovered two crucial findings. Firstly, it is demonstrated that beyond a critical CCL conductance, no further improvement in performance is observed. The procedure used to determine this critical conductance can be used by other researchers in this field to aid in their design of high performing NPMC-based CCLs. Secondly, it is shown that the stability of NPMC-based CCLs can be improved through the use of low equivalent weight ionomers. This represents a completely unexplored pathway for further stability improvements, and also provides new insights into the possible degradation mechanisms occurring in NPMC-based CCLs. These findings have broad implications on all future NPMC-based CCL designs.

Rare Cell Capture in Microfluidic Devices

PubMed Central

Pratt, Erica D.; Huang, Chao; Hawkins, Benjamin G.; Gleghorn, Jason P.; Kirby, Brian J.

2010-01-01

This article reviews existing methods for the isolation, fractionation, or capture of rare cells in microfluidic devices. Rare cell capture devices face the challenge of maintaining the efficiency standard of traditional bulk separation methods such as flow cytometers and immunomagnetic separators while requiring very high purity of the target cell population, which is typically already at very low starting concentrations. Two major classifications of rare cell capture approaches are covered: (1) non-electrokinetic methods (e.g., immobilization via antibody or aptamer chemistry, size-based sorting, and sheath flow and streamline sorting) are discussed for applications using blood cells, cancer cells, and other mammalian cells, and (2) electrokinetic (primarily dielectrophoretic) methods using both electrode-based and insulative geometries are presented with a view towards pathogen detection, blood fractionation, and cancer cell isolation. The included methods were evaluated based on performance criteria including cell type modeled and used, number of steps/stages, cell viability, and enrichment, efficiency, and/or purity. Major areas for improvement are increasing viability and capture efficiency/purity of directly processed biological samples, as a majority of current studies only process spiked cell lines or pre-diluted/lysed samples. Despite these current challenges, multiple advances have been made in the development of devices for rare cell capture and the subsequent elucidation of new biological phenomena; this article serves to highlight this progress as well as the electrokinetic and non-electrokinetic methods that can potentially be combined to improve performance in future studies. PMID:21532971

Endothelial Progenitor Cells as Shuttle of Anticancer Agents.

PubMed

Laurenzana, Anna; Margheri, Francesca; Chillà, Anastasia; Biagioni, Alessio; Margheri, Giancarlo; Calorini, Lido; Fibbi, Gabriella; Del Rosso, Mario

2016-10-01

Cell therapies are treatments in which stem or progenitor cells are stimulated to differentiate into specialized cells able to home to and repair damaged tissues. After their discovery, endothelial progenitor cells (EPCs) stimulated worldwide interest as possible vehicles to perform autologous cell therapy of tumors. Taking into account the tumor-homing properties of EPCs, two different approaches to control cancer progression have been pursued by combining cell-based therapy with gene therapy or with nanomedicine. The first approach is based on the possibility of engineering EPCs to express different transgenes, and the second is based on the capacity of EPCs to take up nanomaterials. Here we review the most important progress covering the following issues: the characterization of bona fide endothelial progenitor cells, their role in tumor vascularization and metastasis, and preclinical data about their use in cell-based tumor therapy, considering antiangiogenic, suicide, immune-stimulating, and oncolytic virus gene therapy. The mixed approach of EPC cell therapy and nanomedicine is discussed in terms of plasmonic-dependent thermoablation and molecular imaging.

Performance of a Fuel-Cell-Powered, Small Electric Airplane Assessed

NASA Technical Reports Server (NTRS)

Berton, Jeffrey J.

2004-01-01

Rapidly emerging fuel-cell-power technologies may be used to launch a new revolution of electric propulsion systems for light aircraft. Future small electric airplanes using fuel cell technologies hold the promise of high reliability, low maintenance, low noise, and - with the exception of water vapor - zero emissions. An analytical feasibility and performance assessment was conducted by NASA Glenn Research Center's Airbreathing Systems Analysis Office of a fuel-cell-powered, propeller-driven, small electric airplane based on a model of the MCR-01 two-place kitplane (Dyn'Aero, Darois, France). This assessment was conducted in parallel with an ongoing effort by the Advanced Technology Products Corporation and the Foundation for Advancing Science and Technology Education. Their project - partially funded by a NASA grant - is to design, build, and fly the first manned, continuously propelled, nongliding electric airplane. In our study, an analytical performance model of a proton exchange membrane (PEM) fuel cell propulsion system was developed and applied to a notional, two-place light airplane modeled after the MCR-01 kitplane. The PEM fuel cell stack was fed pure hydrogen fuel and humidified ambient air via a small automotive centrifugal supercharger. The fuel cell performance models were based on chemical reaction analyses calibrated with published data from the fledgling U.S. automotive fuel cell industry. Electric propeller motors, rated at two shaft power levels in separate assessments, were used to directly drive a two-bladed, variable-pitch propeller. Fuel sources considered were compressed hydrogen gas and cryogenic liquid hydrogen. Both of these fuel sources provided pure, contaminant-free hydrogen for the PEM cells.

On uncertainty quantification of lithium-ion batteries: Application to an LiC6/LiCoO2 cell

NASA Astrophysics Data System (ADS)

Hadigol, Mohammad; Maute, Kurt; Doostan, Alireza

2015-12-01

In this work, a stochastic, physics-based model for Lithium-ion batteries (LIBs) is presented in order to study the effects of parametric model uncertainties on the cell capacity, voltage, and concentrations. To this end, the proposed uncertainty quantification (UQ) approach, based on sparse polynomial chaos expansions, relies on a small number of battery simulations. Within this UQ framework, the identification of most important uncertainty sources is achieved by performing a global sensitivity analysis via computing the so-called Sobol' indices. Such information aids in designing more efficient and targeted quality control procedures, which consequently may result in reducing the LIB production cost. An LiC6/LiCoO2 cell with 19 uncertain parameters discharged at 0.25C, 1C and 4C rates is considered to study the performance and accuracy of the proposed UQ approach. The results suggest that, for the considered cell, the battery discharge rate is a key factor affecting not only the performance variability of the cell, but also the determination of most important random inputs.

Distributed Multi-Cell Resource Allocation with Price Based ICI Coordination in Downlink OFDMA Networks

NASA Astrophysics Data System (ADS)

Lv, Gangming; Zhu, Shihua; Hui, Hui

Multi-cell resource allocation under minimum rate request for each user in OFDMA networks is addressed in this paper. Based on Lagrange dual decomposition theory, the joint multi-cell resource allocation problem is decomposed and modeled as a limited-cooperative game, and a distributed multi-cell resource allocation algorithm is thus proposed. Analysis and simulation results show that, compared with non-cooperative iterative water-filling algorithm, the proposed algorithm can remarkably reduce the ICI level and improve overall system performances.

Sustainable Hypersaline Microbial Fuel Cells: Inexpensive Recyclable Polymer Supports for Carbon Nanotube Conductive Paint Anodes.

PubMed

Grattieri, Matteo; Shivel, Nelson D; Sifat, Iram; Bestetti, Massimiliano; Minteer, Shelley D

2017-05-09

Microbial fuel cells are an emerging technology for wastewater treatment, but to be commercially viable and sustainable, the electrode materials must be inexpensive, recyclable, and reliable. In this study, recyclable polymeric supports were explored for the development of anode electrodes to be applied in single-chamber microbial fuel cells operated in field under hypersaline conditions. The support was covered with a carbon nanotube (CNT) based conductive paint, and biofilms were able to colonize the electrodes. The single-chamber microbial fuel cells with Pt-free cathodes delivered a reproducible power output after 15 days of operation to achieve 12±1 mW m -2 at a current density of 69±7 mA m -2 . The decrease of the performance in long-term experiments was mostly related to inorganic precipitates on the cathode electrode and did not affect the performance of the anode, as shown by experiments in which the cathode was replaced and the fuel cell performance was regenerated. The results of these studies show the feasibility of polymeric supports coated with CNT-based paint for microbial fuel cell applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a high-sensitivity and portable cell using Helmholtz resonance for noninvasive blood glucose-level measurement based on photoacoustic spectroscopy.

PubMed

Tachibana, K; Okada, K; Kobayashi, R; Ishihara, Y

2016-08-01

We describe the possibility of high-sensitivity noninvasive blood glucose measurement based on photoacoustic spectroscopy (PAS). The demand for noninvasive blood glucose-level measurement has increased due to the explosive increase in diabetic patients. We have developed a noninvasive blood glucose-level measurement based on PAS. The conventional method uses a straight-type resonant cell. However, the cell volume is large, which results in a low detection sensitivity and difficult portability. In this paper, a small-sized Helmholtz-type resonant cell is proposed to improve detection sensitivity and portability by reducing the cell dead volume. First, the acoustic property of the small-sized Helmholtz-type resonant cell was evaluated by performing an experiment using a silicone rubber. As a result, the detection sensitivity of the small-sized Helmholtz-type resonant cell was approximately two times larger than that of the conventional straight-type resonant cell. In addition, the inside volume was approximately 30 times smaller. Second, the detection limits of glucose concentration were estimated by performing an experiment using glucose solutions. The experimental results showed that a glucose concentration of approximately 1% was detected by the small-sized Helmholtz-type resonant cell. Although these results on the sensitivity of blood glucose-level measurement are currently insufficient, they suggest that miniaturization of a resonance cell is effective in the application of noninvasive blood glucose-level measurement.

A Field-Portable Cell Analyzer without a Microscope and Reagents

PubMed Central

Oh, Sangwoo; Lee, Moonjin; Hwang, Yongha

2017-01-01

This paper demonstrates a commercial-level field-portable lens-free cell analyzer called the NaviCell (No-stain and Automated Versatile Innovative cell analyzer) capable of automatically analyzing cell count and viability without employing an optical microscope and reagents. Based on the lens-free shadow imaging technique, the NaviCell (162 × 135 × 138 mm3 and 1.02 kg) has the advantage of providing analysis results with improved standard deviation between measurement results, owing to its large field of view. Importantly, the cell counting and viability testing can be analyzed without the use of any reagent, thereby simplifying the measurement procedure and reducing potential errors during sample preparation. In this study, the performance of the NaviCell for cell counting and viability testing was demonstrated using 13 and six cell lines, respectively. Based on the results of the hemocytometer (de facto standard), the error rate (ER) and coefficient of variation (CV) of the NaviCell are approximately 3.27 and 2.16 times better than the commercial cell counter, respectively. The cell viability testing of the NaviCell also showed an ER and CV performance improvement of 5.09 and 1.8 times, respectively, demonstrating sufficient potential in the field of cell analysis. PMID:29286336

Enhanced light harvesting of dye-sensitized solar cells with TiO2 microspheres as light scattering layer

NASA Astrophysics Data System (ADS)

Guan, Yingli; Song, Lixin; Zhou, Yangyang; Yin, Xin; Xie, Xueyao; Xiong, Jie

2017-03-01

Two kinds of TiO2 microspheres (TMS) with average diameter of 1500 nm but different surface were fabricated by solvothermal method from different Ti source. The effect of TMS on the light harvesting and photovoltaic performance of dye-sensitized solar cells (DSSCs)was investigated. The UV-Vis diffusion reflectance spectra and absorption spectra of N719 dye in detached solutions proved that the TMS showed dual functions of light scattering and dye-adsorption which was an important functional material in DSSCs. The results showed that the TMS made from titanium(IV) isopropoxide with rough surface (TMSR) exhibited better photovoltaic performance than that of TMS made from tetrabutyl titanate with smooth surface (TMSS). To further improve the photovoltaic performance, the double-layered DSSCs made of P25 as an underlayer and TMS as a light-scattering layer (P25-TMS) were fabricated. The photovoltaic performance of double-layered DSSCs was higher than that of the single-layered DSSCs with similar thickness. Especially, the DSSCs made of P25 as an underlayer and the TMSR as a light-scattering layer (P25-TMSR) had a highest power conversion efficiency of 7.62%. This was higher than that of single-layered TMSR-based cell (5.54%), P25-based cell (5.75%), and double-layered P25-TMSS-based cell (6.78%) with similar thickness. This was mainly attributed to the large specific surface area, superior light scattering ability, and fast electron transport of TMSR.

Photostick: a method for selective isolation of target cells from culture† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c4sc03676j Click here for additional data file.

PubMed Central

Chien, Miao-Ping; Werley, Christopher A.; Farhi, Samouil L.

2015-01-01

Sorting of target cells from a heterogeneous pool is technically difficult when the selection criterion is complex, e.g. a dynamic response, a morphological feature, or a combination of multiple parameters. At present, mammalian cell selections are typically performed either via static fluorescence (e.g. fluorescence activated cell sorter), via survival (e.g. antibiotic resistance), or via serial operations (flow cytometry, laser capture microdissection). Here we present a simple protocol for selecting cells based on any static or dynamic property that can be identified by video microscopy and image processing. The “photostick” technique uses a cell-impermeant photochemical crosslinker and digital micromirror array-based patterned illumination to immobilize selected cells on the culture dish. Other cells are washed away with mild protease treatment. The crosslinker also labels the selected cells with a fluorescent dye and a biotin for later identification. The photostick protocol preserves cell viability, permits genetic profiling of selected cells, and can be performed with complex functional selection criteria such as neuronal firing patterns. PMID:25705368

Relating Structure to Efficiency in Surfactant-Free Polymer/Fullerene Nanoparticle-Based Organic Solar Cells.

PubMed

Gärtner, Stefan; Clulow, Andrew J; Howard, Ian A; Gilbert, Elliot P; Burn, Paul L; Gentle, Ian R; Colsmann, Alexander

2017-12-13

Nanoparticle dispersions open up an ecofriendly route toward printable organic solar cells. They can be formed from a variety of organic semiconductors by using miniemulsions that employ surfactants to stabilize the nanoparticles in dispersion and to prevent aggregation. However, whenever surfactant-based nanoparticle dispersions have been used to fabricate solar cells, the reported performances remain moderate. In contrast, solar cells from nanoparticle dispersions formed by precipitation (without surfactants) can exhibit power conversion efficiencies close to those of state-of-the-art solar cells processed from blend solutions using chlorinated solvents. In this work, we use small-angle neutron scattering measurements and transient absorption spectroscopy to investigate why surfactant-free nanoparticles give rise to efficient organic solar cells. We show that surfactant-free nanoparticles comprise a uniform distribution of small semiconductor domains, similar to that of bulk-heterojunction films formed using traditional solvent processing. This observation differs from surfactant-based miniemulsion nanoparticles that typically exhibit core-shell structures. Hence, the surfactant-free nanoparticles already possess the optimum morphology for efficient energy conversion before they are assembled into the photoactive layer of a solar cell. This structural property underpins the superior performance of the solar cells containing surfactant-free nanoparticles and is an important design criterion for future nanoparticle inks.

High-performance oxygen reduction catalysts in both alkaline and acidic fuel cells based on pre-treating carbon material and iron precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Ping; Barkholtz, Heather M.; Wang, Ying

We demonstrate a new and simple method for pre-treating the carbon material and iron precursor to prepare oxygen reduction reaction (ORR) catalysts, which can produce super-high performance and stability in alkaline solution, with high performance in acid solution. This strategy using cheap materials is simply controllable. Moreover, it has achieved smaller uniform nanoparticles to exhibit high stability, and the synergetic effect of Fe and N offered much higher performance in ORR than commercial Pt/C, with high maximum power density in alkaline and acid fuel cell test. So it can make this kind of catalysts be the most promising alternatives ofmore » Pt-based catalysts with best performance/price.« less

Peptide-Based Photoelectrochemical Cytosensor Using a Hollow-TiO2/EG/ZnIn2S4 Cosensitized Structure for Ultrasensitive Detection of Early Apoptotic Cells and Drug Evaluation.

PubMed

Wu, Rong; Fan, Gao-Chao; Jiang, Li-Ping; Zhu, Jun-Jie

2018-02-07

The ability to rapidly detect apoptotic cells and accurately evaluate therapeutic effects is significant in cancer research. To address this target, a biocompatible, ultrasensitive photoelectrochemical (PEC) cytosensing platform was developed based on electrochemically reduced graphene (EG)/ZnIn 2 S 4 cosensitized TiO 2 coupled with specific recognition between apoptotic cells and phosphatidylserine-binding peptide (PSBP). In this strategy, the HL-60 cells were selected as a model and C005, nilotinib, and imatinib were selected as apoptosis inducers to show cytosensing performances. In particular, a TiO 2 photoactive substrate was designed as hollow spheres to enhance the PEC performance. Graphene was electrodeposited on the hollow TiO 2 -modified electrode to accelerate electron transfer and increase conductivity, followed by in situ growth of ZnIn 2 S 4 nanocrystals as photosensitizers via successive ionic layer adsorption and reaction method, forming a TiO 2 /EG/ZnIn 2 S 4 cosensitized structure that was used as a PEC matrix to immobilize PSBP for the recognition of early apoptotic cells. The detection of apoptotic cells was based on steric hindrance originating from apoptotic cell capture to induce an obvious decrease in the photocurrent signal. The ultrahigh sensitivity of the cytosensor resulted from enhanced PEC performance, bioactivity, and high binding affinity between PSBP and apoptotic cells. Compared with other assays, incorporate toxic elements were avoided, such as Cd, Ru, and Te, which ensured normal cell growth and are appropriate for cell analysis. The designed PEC cytosensor showed a low detection limit of apoptotic cells (as low as three cells), a wide linear range from 1 × 10 3 to 5 × 10 7 cells/mL, and an accurate evaluation of therapeutic effects. It also exhibited good specificity, reproducibility, and stability.

Different methods to fabricate efficient planar perovskite solar cells based on solution-processing Nb2O5 as electron transporting layer

NASA Astrophysics Data System (ADS)

Guo, Heng; Yang, Jian; Pu, Bingxue; Zhang, Haiyan; Niu, Xiaobin

2018-01-01

Organo-lead perovskites as light harvesters have represented a hot field of research on high-efficiency perovskite solar cells. Previous approaches to increasing the solar cell efficiency have focused on optimization of the morphology of perovskite film. In fact, the electron transporting layer (ETL) also has a significant impact on solar cell performance. Herein, we introduce a facile and low temperature solution-processing method to deposit Nb2O5 film as ETL for PSCs. Based on Nb2O5 ETL, we investigate the effect of the annealing time for the perovskite films via different solution processing, relating it to the perovskite film morphology and its influence on the device working mechanisms. These results shed light on the origin of photovoltaic performance voltage in perovskite solar cells, and provide a path to further increase their efficiency.

Efficient globally optimal segmentation of cells in fluorescence microscopy images using level sets and convex energy functionals.

PubMed

Bergeest, Jan-Philip; Rohr, Karl

2012-10-01

In high-throughput applications, accurate and efficient segmentation of cells in fluorescence microscopy images is of central importance for the quantification of protein expression and the understanding of cell function. We propose an approach for segmenting cell nuclei which is based on active contours using level sets and convex energy functionals. Compared to previous work, our approach determines the global solution. Thus, the approach does not suffer from local minima and the segmentation result does not depend on the initialization. We consider three different well-known energy functionals for active contour-based segmentation and introduce convex formulations of these functionals. We also suggest a numeric approach for efficiently computing the solution. The performance of our approach has been evaluated using fluorescence microscopy images from different experiments comprising different cell types. We have also performed a quantitative comparison with previous segmentation approaches. Copyright © 2012 Elsevier B.V. All rights reserved.

Rapid Identification of Cell-Specific, Internalizing RNA Aptamers with Bioinformatics Analyses of a Cell-Based Aptamer Selection

PubMed Central

Thiel, William H.; Bair, Thomas; Peek, Andrew S.; Liu, Xiuying; Dassie, Justin; Stockdale, Katie R.; Behlke, Mark A.; Miller, Francis J.; Giangrande, Paloma H.

2012-01-01

Background The broad applicability of RNA aptamers as cell-specific delivery tools for therapeutic reagents depends on the ability to identify aptamer sequences that selectively access the cytoplasm of distinct cell types. Towards this end, we have developed a novel approach that combines a cell-based selection method (cell-internalization SELEX) with high-throughput sequencing (HTS) and bioinformatics analyses to rapidly identify cell-specific, internalization-competent RNA aptamers. Methodology/Principal Findings We demonstrate the utility of this approach by enriching for RNA aptamers capable of selective internalization into vascular smooth muscle cells (VSMCs). Several rounds of positive (VSMCs) and negative (endothelial cells; ECs) selection were performed to enrich for aptamer sequences that preferentially internalize into VSMCs. To identify candidate RNA aptamer sequences, HTS data from each round of selection were analyzed using bioinformatics methods: (1) metrics of selection enrichment; and (2) pairwise comparisons of sequence and structural similarity, termed edit and tree distance, respectively. Correlation analyses of experimentally validated aptamers or rounds revealed that the best cell-specific, internalizing aptamers are enriched as a result of the negative selection step performed against ECs. Conclusions and Significance We describe a novel approach that combines cell-internalization SELEX with HTS and bioinformatics analysis to identify cell-specific, cell-internalizing RNA aptamers. Our data highlight the importance of performing a pre-clear step against a non-target cell in order to select for cell-specific aptamers. We expect the extended use of this approach to enable the identification of aptamers to a multitude of different cell types, thereby facilitating the broad development of targeted cell therapies. PMID:22962591

Hydroxamate anchors for improved photoconversion in dye-sensitized solar cells.

PubMed

Brewster, Timothy P; Konezny, Steven J; Sheehan, Stafford W; Martini, Lauren A; Schmuttenmaer, Charles A; Batista, Victor S; Crabtree, Robert H

2013-06-03

We present the first analysis of performance of hydroxamate linkers as compared to carboxylate and phosphonate groups when anchoring ruthenium-polypyridyl dyes to TiO2 surfaces in dye-sensitized solar cells (DSSCs). The study provides fundamental insight into structure/function relationships that are critical for cell performance. Our DSSCs have been produced by using newly synthesized dye molecules and characterized by combining measurements and simulations of experimental current density-voltage (J-V) characteristic curves. We show that the choice of anchoring group has a direct effect on the overall sunlight-to-electricity conversion efficiency (η), with hydroxamate anchors showing the best performance. Solar cells based on the pyridyl-hydroxamate complex exhibit higher efficiency since they suppress electron transfer from the photoanode to the electrolyte and have superior photoinjection characteristics. These findings suggest that hydroxamate anchoring groups should be particularly valuable in DSSCs and photocatalytic applications based on molecular adsorbates covalently bound to semiconductor surfaces. In contrast, analogous acetylacetonate anchors might undergo decomposition under similar conditions suggesting limited potential in future applications.

Bioreactor expansion of human mesenchymal stem cells according to GMP requirements.

PubMed

Elseberg, Christiane L; Salzig, Denise; Czermak, Peter

2015-01-01

In cell therapy, the use of autologous and allogenic human mesenchymal stem cells is rising. Accordingly, the supply of cells for clinical applications in highest quality is required. As hMSCs are considered as an advanced therapy medicinal products (ATMP), they underlie the requirements of GMP and PAT according to the authorities (FDA and EMA). The production process of these cells must therefore be documented according to GMP, which is usually performed via a GMP protocol based on standard operating procedures. This chapter provides an example of such a GMP protocol for hMSC, here a genetically modified allogenic cell line, based on a production process in a microcarrier-based stirred tank reactor including process monitoring according to PAT and final product quality assurance.

Probabilistic Analysis of Solid Oxide Fuel Cell Based Hybrid Gas Turbine System

NASA Technical Reports Server (NTRS)

Gorla, Rama S. R.; Pai, Shantaram S.; Rusick, Jeffrey J.

2003-01-01

The emergence of fuel cell systems and hybrid fuel cell systems requires the evolution of analysis strategies for evaluating thermodynamic performance. A gas turbine thermodynamic cycle integrated with a fuel cell was computationally simulated and probabilistically evaluated in view of the several uncertainties in the thermodynamic performance parameters. Cumulative distribution functions and sensitivity factors were computed for the overall thermal efficiency and net specific power output due to the uncertainties in the thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of criteria for gas turbine performance.

Solar cell and module performance assessment based on indoor calibration methods

NASA Astrophysics Data System (ADS)

Bogus, K.

A combined space/terrestrial solar cell test calibration method that requires five steps and can be performed indoors is described. The test conditions are designed to qualify the cell or module output data in standard illumination and temperature conditions. Measurements are made of the short-circuit current, the open circuit voltage, the maximum power, the efficiency, and the spectral response. Standard sunlight must be replicated both in earth surface and AM0 conditions; Xe lamps are normally used for the light source, with spectral measurements taken of the light. Cell and module spectral response are assayed by using monochromators and narrow band pass monochromatic filters. Attention is required to define the performance characteristics of modules under partial shadowing. Error sources that may effect the measurements are discussed, as are previous cell performance testing and calibration methods and their effectiveness in comparison with the behaviors of satellite solar power panels.

Machine learning-based methods for prediction of linear B-cell epitopes.

PubMed

Wang, Hsin-Wei; Pai, Tun-Wen

2014-01-01

B-cell epitope prediction facilitates immunologists in designing peptide-based vaccine, diagnostic test, disease prevention, treatment, and antibody production. In comparison with T-cell epitope prediction, the performance of variable length B-cell epitope prediction is still yet to be satisfied. Fortunately, due to increasingly available verified epitope databases, bioinformaticians could adopt machine learning-based algorithms on all curated data to design an improved prediction tool for biomedical researchers. Here, we have reviewed related epitope prediction papers, especially those for linear B-cell epitope prediction. It should be noticed that a combination of selected propensity scales and statistics of epitope residues with machine learning-based tools formulated a general way for constructing linear B-cell epitope prediction systems. It is also observed from most of the comparison results that the kernel method of support vector machine (SVM) classifier outperformed other machine learning-based approaches. Hence, in this chapter, except reviewing recently published papers, we have introduced the fundamentals of B-cell epitope and SVM techniques. In addition, an example of linear B-cell prediction system based on physicochemical features and amino acid combinations is illustrated in details.

Performance enhancement technique of visible light communications using passive photovoltaic cell

NASA Astrophysics Data System (ADS)

Wu, Jhao-Ting; Chow, Chi-Wai; Liu, Yang; Hsu, Chin-Wei; Yeh, Chien-Hung

2017-06-01

The light emitting diode (LED) based visible light communication (VLC) system can provide lighting and communication simultaneously. It has attracted much attenuation recently. As the photovoltaic cell (also known as solar cell) is physically flexible, low cost, and easily available, it could be a good choice for the VLC receiver (Rx). Furthermore, besides acting as the VLC Rx, the solar cell can convert VLC signal into electricity for charging up the Rx devices. Hence, it could be a promising candidate for the future internet-of-thing (IoT) networks. However, using solar cell as VLC Rx is challenging, since the response of the solar cell is highly limited and it will limit the VLC data rate. In this work, we propose and demonstrate for the first time using pre-distortion Manchester coding (MC) signal to enhance the signal performance of solar cell Rx based VLC. The proposed scheme can significantly mitigate the slow response, as well as the direct-current (DC) wandering effect of the solar cell; hence 50 times increase in data rate can be experimentally achieved.

Theoretical investigation of the use of nanocages with an adsorbed halogen atom as anode materials in metal-ion batteries.

PubMed

Razavi, Razieh; Abrishamifar, Seyyed Milad; Rajaei, Gholamreza Ebrahimzadeh; Kahkha, Mohammad Reza Rezaei; Najafi, Meysam

2018-02-21

The applicability of C 44 , B 22 N 22 , Ge 44 , and Al 22 P 22 nanocages, as well as variants of those nanocages with an adsorbed halogen atom, as high-performance anode materials in Li-ion, Na-ion, and K-ion batteries was investigated theoretically via density functional theory. The results obtained indicate that, among the nanocages with no adsorbed halogen atom, Al 22 P 22 would be the best candidate for a novel anode material for use in metal-ion batteries. Calculations also suggest that K-ion batteries which utilize these nanocages as anode materials would give better performance and would yield higher cell voltages than the corresponding Li-ion and Na-ion batteries with nanocage-based anodes. Also, the results for the nanocages with an adsorbed halogen atom imply that employing them as anode materials would lead to higher cell voltages and better metal-ion battery performance than if the nanocages with no adsorbed halogen atom were to be used as anode materials instead. Results further implied that nanocages with an adsorbed F atom would give higher cell voltages and better battery performance than nanocages with an adsorbed Cl or Br atom. We were ultimately able to conclude that a K-ion battery that utilized Al 21 P 22 with an adsorbed F atom as its anode material would afford the best metal-ion battery performance; we therefore propose this as a novel highly efficient metal-ion battery. Graphical abstract The results of a theoretical investigation indicated that Al 22 P 22 is a better candidate for a high-performance anode material in metal-ion batteries than Ge 44 is. Calculations also showed that K-ion batteries with nanocage-based anodes would produce higher cell voltages and perform better than the equivalent Li-ion and Na-ion batteries with nanocage-based anodes, and that anodes based on nanocages with an adsorbed F atom would perform better than anodes based on nanocages with an adsorbed Cl or Br atom.

Reliable binary cell-fate decisions based on oscillations

NASA Astrophysics Data System (ADS)

Pfeuty, B.; Kaneko, K.

2014-02-01

Biological systems have often to perform binary decisions under highly dynamic and noisy environments, such as during cell-fate determination. These decisions can be implemented by two main bifurcation mechanisms based on the transitions from either monostability or oscillation to bistability. We compare these two mechanisms by using stochastic models with time-varying fields and by establishing asymptotic formulas for the choice probabilities. Different scaling laws for decision sensitivity with respect to noise strength and signal timescale are obtained, supporting a role for oscillatory dynamics in performing noise-robust and temporally tunable binary decision-making. This result provides a rationale for recent experimental evidences showing that oscillatory expression of proteins often precedes binary cell-fate decisions.

Tilted pillar array fabrication by the combination of proton beam writing and soft lithography for microfluidic cell capture Part 2: Image sequence analysis based evaluation and biological application.

PubMed

Járvás, Gábor; Varga, Tamás; Szigeti, Márton; Hajba, László; Fürjes, Péter; Rajta, István; Guttman, András

2018-02-01

As a continuation of our previously published work, this paper presents a detailed evaluation of a microfabricated cell capture device utilizing a doubly tilted micropillar array. The device was fabricated using a novel hybrid technology based on the combination of proton beam writing and conventional lithography techniques. Tilted pillars offer unique flow characteristics and support enhanced fluidic interaction for improved immunoaffinity based cell capture. The performance of the microdevice was evaluated by an image sequence analysis based in-house developed single-cell tracking system. Individual cell tracking allowed in-depth analysis of the cell-chip surface interaction mechanism from hydrodynamic point of view. Simulation results were validated by using the hybrid device and the optimized surface functionalization procedure. Finally, the cell capture capability of this new generation microdevice was demonstrated by efficiently arresting cells from a HT29 cell-line suspension. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diketopyrrolopyrrole Polymers for Organic Solar Cells.

PubMed

Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2016-01-19

Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with fullerenes via solution processing. The width of these fibers and the photon energy loss, defined as the energy difference between optical band gap and open-circuit voltage, together govern to a large extent the quantum efficiency for charge generation in these blends and thereby the power conversion efficiency of the photovoltaic devices. Lowering the photon energy loss and maintaining a high quantum yield for charge generation is identified as a major pathway to enhance the performance of organic solar cells. This can be achieved by controlling the structural purity of the materials and further control over morphology formation. We hope that this Account contributes to improved design strategies of DPP polymers that are required to realize new breakthroughs in organic solar cell performance in the future.

Classification of cancerous cells based on the one-class problem approach

NASA Astrophysics Data System (ADS)

Murshed, Nabeel A.; Bortolozzi, Flavio; Sabourin, Robert

1996-03-01

One of the most important factors in reducing the effect of cancerous diseases is the early diagnosis, which requires a good and a robust method. With the advancement of computer technologies and digital image processing, the development of a computer-based system has become feasible. In this paper, we introduce a new approach for the detection of cancerous cells. This approach is based on the one-class problem approach, through which the classification system need only be trained with patterns of cancerous cells. This reduces the burden of the training task by about 50%. Based on this approach, a computer-based classification system is developed, based on the Fuzzy ARTMAP neural networks. Experimental results were performed using a set of 542 patterns taken from a sample of breast cancer. Results of the experiment show 98% correct identification of cancerous cells and 95% correct identification of non-cancerous cells.

Achieving High Performance Perovskite Solar Cells

NASA Astrophysics Data System (ADS)

Yang, Yang

2015-03-01

Recently, metal halide perovskite based solar cell with the characteristics of rather low raw materials cost, great potential for simple process and scalable production, and extreme high power conversion efficiency (PCE), have been highlighted as one of the most competitive technologies for next generation thin film photovoltaic (PV). In UCLA, we have realized an efficient pathway to achieve high performance pervoskite solar cells, where the findings are beneficial to this unique materials/devices system. Our recent progress lies in perovskite film formation, defect passivation, transport materials design, interface engineering with respect to high performance solar cell, as well as the exploration of its applications beyond photovoltaics. These achievements include: 1) development of vapor assisted solution process (VASP) and moisture assisted solution process, which produces perovskite film with improved conformity, high crystallinity, reduced recombination rate, and the resulting high performance; 2) examination of the defects property of perovskite materials, and demonstration of a self-induced passivation approach to reduce carrier recombination; 3) interface engineering based on design of the carrier transport materials and the electrodes, in combination with high quality perovskite film, which delivers 15 ~ 20% PCEs; 4) a novel integration of bulk heterojunction to perovskite solar cell to achieve better light harvest; 5) fabrication of inverted solar cell device with high efficiency and flexibility and 6) exploration the application of perovskite materials to photodetector. Further development in film, device architecture, and interfaces will lead to continuous improved perovskite solar cells and other organic-inorganic hybrid optoelectronics.

Thin film module electrical configuration versus electrical performance

NASA Technical Reports Server (NTRS)

Morel, D. L.

1985-01-01

The as made and degraded states of thin film silicon (TFS) based modules have been modelled in terms of series resistance losses. The origins of these losses lie in interface and bulk regions of the devices. When modules degrade under light exposure, increases occur in both the interface and bulk components of the loss based on series resistance. Actual module performance can thus be simulated by use of only one unknown parameter, shunt losses. Use of the simulation to optimize module design indicates that the current design of 25 cells per linear foot is near optimum. Degradation performance suggests a shift to approx. 35 cells to effect maximum output for applications not constrained to 12 volts. Earlier studies of energy based performance and tandem structures should be updated to include stability factors, not only the initial loss factor tested here, but also appropriate annealing factors.

What makes lithium substituted polyacrylic acid a better binder than polyacrylic acid for silicon-graphite composite anodes?

DOE PAGES

Hays, Kevin A.; Ruther, Rose E.; Kukay, Alexander J.; ...

2018-03-04

Lithium substituted polyacrylic acid (LiPAA) has previously been demonstrated as a superior binder over polyacrylic acid (PAA) for Si anodes, but from where does this enhanced performance arise? In this paper, full cells are assembled with PAA and LiPAA based Si-graphite composite anodes that dried at temperatures from 100 °C to 200 °C. The performance of full cells containing PAA based Si-graphite anodes largely depend on the secondary drying temperature, as decomposition of the binder is correlated to increased electrode moisture and a rise in cell impedance. Full cells containing LiPAA based Si-graphite composite electrodes display better Coulombic efficiency thanmore » those with PAA, because of the electrochemical reduction of the PAA binder. This is identified by attenuated total reflectance Fourier transform infrared spectrometry and observed gassing during the electrochemical reaction. Finally, Coulombic losses from the PAA and Si SEI, along with depletion of the Si capacity in the anode results in progressive underutilization of the cathode and full cell capacity loss.« less

What makes lithium substituted polyacrylic acid a better binder than polyacrylic acid for silicon-graphite composite anodes?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hays, Kevin A.; Ruther, Rose E.; Kukay, Alexander J.

Lithium substituted polyacrylic acid (LiPAA) has previously been demonstrated as a superior binder over polyacrylic acid (PAA) for Si anodes, but from where does this enhanced performance arise? In this paper, full cells are assembled with PAA and LiPAA based Si-graphite composite anodes that dried at temperatures from 100 °C to 200 °C. The performance of full cells containing PAA based Si-graphite anodes largely depend on the secondary drying temperature, as decomposition of the binder is correlated to increased electrode moisture and a rise in cell impedance. Full cells containing LiPAA based Si-graphite composite electrodes display better Coulombic efficiency thanmore » those with PAA, because of the electrochemical reduction of the PAA binder. This is identified by attenuated total reflectance Fourier transform infrared spectrometry and observed gassing during the electrochemical reaction. Finally, Coulombic losses from the PAA and Si SEI, along with depletion of the Si capacity in the anode results in progressive underutilization of the cathode and full cell capacity loss.« less

What makes lithium substituted polyacrylic acid a better binder than polyacrylic acid for silicon-graphite composite anodes?

NASA Astrophysics Data System (ADS)

Hays, Kevin A.; Ruther, Rose E.; Kukay, Alexander J.; Cao, Pengfei; Saito, Tomonori; Wood, David L.; Li, Jianlin

2018-04-01

Lithium substituted polyacrylic acid (LiPAA) has previously been demonstrated as a superior binder over polyacrylic acid (PAA) for Si anodes, but from where does this enhanced performance arise? In this study, full cells are assembled with PAA and LiPAA based Si-graphite composite anodes that dried at temperatures from 100 °C to 200 °C. The performance of full cells containing PAA based Si-graphite anodes largely depend on the secondary drying temperature, as decomposition of the binder is correlated to increased electrode moisture and a rise in cell impedance. Full cells containing LiPAA based Si-graphite composite electrodes display better Coulombic efficiency than those with PAA, because of the electrochemical reduction of the PAA binder. This is identified by attenuated total reflectance Fourier transform infrared spectrometry and observed gassing during the electrochemical reaction. Coulombic losses from the PAA and Si SEI, along with depletion of the Si capacity in the anode results in progressive underutilization of the cathode and full cell capacity loss.

High-performance liquid-catalyst fuel cell for direct biomass-into-electricity conversion.

PubMed

Liu, Wei; Mu, Wei; Deng, Yulin

2014-12-01

Herein, we report high-performance fuel cells that are catalyzed solely by polyoxometalate (POM) solution without any solid metal or metal oxide. The novel design of the liquid-catalyst fuel cells (LCFC) changes the traditional gas-solid-surface heterogeneous reactions to liquid-catalysis reactions. With this design, raw biomasses, such as cellulose, starch, and even grass or wood powders can be directly converted into electricity. The power densities of the fuel cell with switchgrass (dry powder) and bush allamanda (freshly collected) are 44 mW cm(-2) and 51 mW cm(-2) respectively. For the cellulose-based biomass fuel cell, the power density is almost 3000 times higher than that of cellulose-based microbial fuel cells. Unlike noble-metal catalysts, POMs are tolerant to most organic and inorganic contaminants. Therefore, almost any raw biomass can be used directly to produce electricity without prior purification. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

FISH-Flow, a protocol for the concurrent detection of mRNA and protein in single cells using fluorescence in situ hybridization and flow cytometry

PubMed Central

Arrigucci, Riccardo; Bushkin, Yuri; Radford, Felix; Lakehal, Karim; Vir, Pooja; Pine, Richard; Martin, December; Sugarman, Jeffrey; Zhao, Yanlin; Yap, George S; Lardizabal, Alfred A; Tyagi, Sanjay; Gennaro, Maria Laura

2017-01-01

We describe a flow-cytometry-based protocol for intracellular mRNA measurements in nonadherent mammalian cells using fluorescence in situ hybridization (FISH) probes. The method, which we call FISH-Flow, allows for high-throughput multiparametric measurements of gene expression, a task that was not feasible with earlier, microscopy-based approaches. The FISH-Flow protocol involves cell fixation, permeabilization and hybridization with a set of fluorescently labeled oligonucleotide probes. In this protocol, surface and intracellular protein markers can also be stained with fluorescently labeled antibodies for simultaneous protein and mRNA measurement. Moreover, a semiautomated, single-tube version of the protocol can be performed with a commercially available cell-wash device that reduces cell loss, operator time and interoperator variability. It takes ~30 h to perform this protocol. An example of FISH-Flow measurements of cytokine mRNA induction by ex vivo stimulation of primed T cells with specific antigens is described. PMID:28518171

On the impact of water activity on reversal tolerant fuel cell anode performance and durability

NASA Astrophysics Data System (ADS)

Hong, Bo Ki; Mandal, Pratiti; Oh, Jong-Gil; Litster, Shawn

2016-10-01

Durability of polymer electrolyte fuel cells in automotive applications can be severely affected by hydrogen starvation arising due to transients during the drive-cycle. It causes individual cell voltage reversal, yielding water electrolysis and carbon corrosion reactions at the anode, ultimately leading to catastrophic cell failure. A popular material-based mitigation strategy is to employ a reversal tolerant anode (RTA) that includes oxygen evolution reaction (OER) catalyst (e.g., IrO2) to promote water electrolysis over carbon corrosion. Here we report that RTA performance surprisingly drops under not only water-deficient but also water-excess conditions. This presents a significant technical challenge since the most common triggers for cell reversal involve excess liquid water. Our findings from detailed electrochemical diagnostics and nano-scale X-ray computed tomography provide insight into how automotive fuel cells can overcome critical vulnerabilities using material-based solutions. Our work also highlights the need for improved materials, electrode designs, and operation strategies for robust RTAs.

PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems

PubMed Central

Ghaffarizadeh, Ahmadreza; Mumenthaler, Shannon M.

2018-01-01

Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal “virtual laboratory” for such multicellular systems simulates both the biochemical microenvironment (the “stage”) and many mechanically and biochemically interacting cells (the “players” upon the stage). PhysiCell—physics-based multicellular simulator—is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility “out of the box.” The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a “cellular cargo delivery” system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also represents a significant independent code base for replicating results from other simulation platforms. The PhysiCell source code, examples, documentation, and support are available under the BSD license at http://PhysiCell.MathCancer.org and http://PhysiCell.sf.net. PMID:29474446

Impurities in silicon solar cells

NASA Technical Reports Server (NTRS)

Hopkins, R. H.

1985-01-01

Metallic impurities, both singly and in combinations, affect the performance of silicon solar cells. Czochralski silicon web crystals were grown with controlled additions of secondary impurities. The primary electrical dopants were boron and phosphorus. The silicon test ingots were grown under controlled and carefully monitored conditions from high-purity charge and dopant material to minimize unintentional contamination. Following growth, each crystal was characterized by chemical, microstructural, electrical, and solar cell tests to provide a detailed and internally consistent description of the relationships between silicon impurity concentration and solar cell performance. Deep-level spectroscopy measurements were used to measure impurity concentrations at levels below the detectability of other techniques and to study thermally-induced changes in impurity activity. For the majority of contaminants, impurity-induced performance loss is due to a reduction of the base diffusion length. From these observations, a semi-empirical model which predicts cell performance as a function of metal impurity concentration was formulated. The model was then used successfully to predict the behavior of solar cells bearing as many as 11 different impurities.

Research on major antitumor active components in Zi-Cao-Cheng-Qi decoction based on hollow fiber cell fishing with high performance liquid chromatography.

PubMed

Li, Miaomiao; Hu, Shuang; Chen, Xuan; Wang, Runqin; Bai, Xiaohong

2018-02-05

Hollow fiber cell fishing (HFCF) based on hepatoma HepG-2 cells, human renal tubular ACHN cells or human cervical carcinoma HeLa cells, coupled with high-performance liquid chromatography (HPLC), was developed and employed to research the major active components in Zi-Cao-Cheng-Qi decoction both in vitro and in vivo. The research showed that the active components, such as hesperidin, magnolol, honokiol, shikonin, emodin and β,β'-dimethylacrylshikonin were screened out by HFCF based on the cancer cells in vitro, furthermore they can be absorbed into blood and reach in the target organ, and some of the active components can be fished by the cells and maintain effective concentrations. Before application of HFCF with HPLC, cell growth state, cell survival rate, positive effect on screening results binding between active centers on the fiber and target components, repeatability of retention times and relative peak areas of the target analytes were analysed and investigated. In short, HFCF with HPLC is a simple, inexpensive, effective, and reliable method that can be used in researching active components from traditional Chinese medicine (TCM) and its formula both in vitro and in vivo, elucidating preliminarily the TCM characteristics of multiple components and multiple targets, laying a foundation for expounding the antitumor efficacy material basis in TCM. Copyright © 2017 Elsevier B.V. All rights reserved.

LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. E. O'Brien; R. C. O'Brien; X. Zhang

2011-11-01

Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cellmore » and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.« less

Scalable 96-well Plate Based iPSC Culture and Production Using a Robotic Liquid Handling System.

PubMed

Conway, Michael K; Gerger, Michael J; Balay, Erin E; O'Connell, Rachel; Hanson, Seth; Daily, Neil J; Wakatsuki, Tetsuro

2015-05-14

Continued advancement in pluripotent stem cell culture is closing the gap between bench and bedside for using these cells in regenerative medicine, drug discovery and safety testing. In order to produce stem cell derived biopharmaceutics and cells for tissue engineering and transplantation, a cost-effective cell-manufacturing technology is essential. Maintenance of pluripotency and stable performance of cells in downstream applications (e.g., cell differentiation) over time is paramount to large scale cell production. Yet that can be difficult to achieve especially if cells are cultured manually where the operator can introduce significant variability as well as be prohibitively expensive to scale-up. To enable high-throughput, large-scale stem cell production and remove operator influence novel stem cell culture protocols using a bench-top multi-channel liquid handling robot were developed that require minimal technician involvement or experience. With these protocols human induced pluripotent stem cells (iPSCs) were cultured in feeder-free conditions directly from a frozen stock and maintained in 96-well plates. Depending on cell line and desired scale-up rate, the operator can easily determine when to passage based on a series of images showing the optimal colony densities for splitting. Then the necessary reagents are prepared to perform a colony split to new plates without a centrifugation step. After 20 passages (~3 months), two iPSC lines maintained stable karyotypes, expressed stem cell markers, and differentiated into cardiomyocytes with high efficiency. The system can perform subsequent high-throughput screening of new differentiation protocols or genetic manipulation designed for 96-well plates. This technology will reduce the labor and technical burden to produce large numbers of identical stem cells for a myriad of applications.

Stepwise heating in Stille polycondensation toward no batch-to-batch variations in polymer solar cell performance.

PubMed

Lee, Sang Myeon; Park, Kwang Hyun; Jung, Seungon; Park, Hyesung; Yang, Changduk

2018-05-14

For a given π-conjugated polymer, the batch-to-batch variations in molecular weight (M w ) and polydispersity index (Ð) can lead to inconsistent process-dependent material properties and consequent performance variations in the device application. Using a stepwise-heating protocol in the Stille polycondensation in conjunction with optimized processing, we obtained an ultrahigh-quality PTB7 polymer having high M w and very narrow Ð. The resulting ultrahigh-quality polymer-based solar cells demonstrate up to 9.97% power conversion efficiencies (PCEs), which is over 24% enhancement from the control devices fabricated with commercially available PTB7. Moreover, we observe almost negligible batch-to-batch variations in the overall PCE values from ultrahigh-quality polymer-based devices. The proposed stepwise polymerization demonstrates a facile and effective strategy for synthesizing high-quality semiconducting polymers that can significantly improve device yield in polymer-based solar cells, an important factor for the commercialization of organic solar cells, by mitigating device-to-device variations.

n-MoS2/p-Si Solar Cells with Al2O3 Passivation for Enhanced Photogeneration.

PubMed

Rehman, Atteq Ur; Khan, Muhammad Farooq; Shehzad, Muhammad Arslan; Hussain, Sajjad; Bhopal, Muhammad Fahad; Lee, Sang Hee; Eom, Jonghwa; Seo, Yongho; Jung, Jongwan; Lee, Soo Hong

2016-11-02

Molybdenum disulfide (MoS 2 ) has recently emerged as a promising candidate for fabricating ultrathin-film photovoltaic devices. These devices exhibit excellent photovoltaic performance, superior flexibility, and low production cost. Layered MoS 2 deposited on p-Si establishes a built-in electric field at MoS 2 /Si interface that helps in photogenerated carrier separation for photovoltaic operation. We propose an Al 2 O 3 -based passivation at the MoS 2 surface to improve the photovoltaic performance of bulklike MoS 2 /Si solar cells. Interestingly, it was observed that Al 2 O 3 passivation enhances the built-in field by reduction of interface trap density at surface. Our device exhibits an improved power conversion efficiency (PCE) of 5.6%, which to our knowledge is the highest efficiency among all bulklike MoS 2 -based photovoltaic cells. The demonstrated results hold the promise for integration of bulklike MoS 2 films with Si-based electronics to develop highly efficient photovoltaic cells.

Simulation and optimization performance of GaAs/GaAs0.5Sb0.5/GaSb mechanically stacked tandem solar cells

NASA Astrophysics Data System (ADS)

Tayubi, Y. R.; Suhandi, A.; Samsudin, A.; Arifin, P.; Supriyatman

2018-05-01

Different approaches have been made in order to reach higher solar cells efficiencies. Concepts for multilayer solar cells have been developed. This can be realised if multiple individual single junction solar cells with different suitably chosen band gaps are connected in series in multi-junction solar cells. In our work, we have simulated and optimized solar cells based on the system mechanically stacked using computer simulation and predict their maximum performance. The structures of solar cells are based on the single junction GaAs, GaAs0.5Sb0.5 and GaSb cells. We have simulated each cell individually and extracted their optimal parameters (layer thickness, carrier concentration, the recombination velocity, etc), also, we calculated the efficiency of each cells optimized by separation of the solar spectrum in bands where the cell is sensible for the absorption. The optimal values of conversion efficiency have obtained for the three individual solar cells and the GaAs/GaAs0.5Sb0.5/GaSb tandem solar cells, that are: η = 19,76% for GaAs solar cell, η = 8,42% for GaAs0,5Sb0,5 solar cell, η = 4, 84% for GaSb solar cell and η = 33,02% for GaAs/GaAs0.5Sb0.5/GaSb tandem solar cell.

Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer - a promising material for high-performance solar cells

NASA Astrophysics Data System (ADS)

Toušek, J.; Toušková, J.; Remeš, Z.; Chomutová, R.; Čermák, J.; Helgesen, M.; Carlé, J. E.; Krebs, F. C.

2015-12-01

Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDTTHD - DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements.

Semiconductor Nanocrystals as Light Harvesters in Solar Cells

PubMed Central

Etgar, Lioz

2013-01-01

Photovoltaic cells use semiconductors to convert sunlight into electrical current and are regarded as a key technology for a sustainable energy supply. Quantum dot-based solar cells have shown great potential as next generation, high performance, low-cost photovoltaics due to the outstanding optoelectronic properties of quantum dots and their multiple exciton generation (MEG) capability. This review focuses on QDs as light harvesters in solar cells, including different structures of QD-based solar cells, such as QD heterojunction solar cells, QD-Schottky solar cells, QD-sensitized solar cells and the recent development in organic-inorganic perovskite heterojunction solar cells. Mechanisms, procedures, advantages, disadvantages and the latest results obtained in the field are described. To summarize, a future perspective is offered. PMID:28809318

Enhanced photovoltaic performance of an inclined nanowire array solar cell.

PubMed

Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

2015-11-30

An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays.

Cell-based delivery of glucagon-like peptide-1 using encapsulated mesenchymal stem cells.

PubMed

Wallrapp, Christine; Thoenes, Eric; Thürmer, Frank; Jork, Anette; Kassem, Moustapha; Geigle, Peter

2013-01-01

Glucagon-like peptide-1 (GLP-1) CellBeads are cell-based implants for the sustained local delivery of bioactive factors. They consist of GLP-1 secreting mesenchymal stem cells encapsulated in a spherically shaped immuno-isolating alginate matrix. A highly standardized and reproducible encapsulation method is described for the manufacturing of homogeneous CellBeads. Viability and sustained secretion was shown for the recombinant GLP-1 and the cell endogenous bioactive factors like vascular endothelial growth factor, neurotrophin 3 (NT-3) and glial cell line-derived neurotrophic factor. Manufacturing and quality control is performed in compliance with good manufacturing practice and fulfils all regulatory requirements for human clinical use. GLP-1 CellBeads combine the neuro- and cardioprotective properties of both GLP-1 and mesenchymal stem cells. First promising results were obtained from preclinical studies and an ongoing safety trial in humans but further studies have to prove the overall potential of CellBead technology in cell-based regenerative medicine.

Speed, Dissipation, and Accuracy in Early T-cell Recognition

NASA Astrophysics Data System (ADS)

Cui, Wenping; Mehta, Pankaj

In the immune system, T cells can perform self-foreign discrimination with great foreign ligand sensitivity, high decision speed and low energy cost. There is significant evidence T-cells achieve such great performance with a mechanism: kinetic proofreading(KPR). KPR-based mechanisms actively consume energy to increase the specificity of T-cell recognition. An important theoretical question arises: how to understand trade-offs and fundamental limits on accuracy, speed, and dissipation (energy consumption). Recent theoretical work suggests that it is always possible to reduce the the error of KPR-based mechanisms by waiting longer and/or consuming more energy. Surprisingly, we find that this is not the case and that there actually exists an optimal point in the speed-energy-accuracy plane for KPR and its generalizations. This work was supported by NIH R35 and Simons MMLS Grant.

Superthin Solar Cells Based on AIIIBV/Ge Heterostructures

NASA Astrophysics Data System (ADS)

Pakhanov, N. A.; Pchelyakov, O. P.; Vladimirov, V. M.

2017-11-01

A comparative analysis of the prospects of creating superthin, light-weight, and highly efficient solar cells based on AIIIBV/InGaAs and AIIIBV/Ge heterostructures is performed. Technological problems and prospects of each variant are discussed. A method of thinning of AIIIBV/Ge heterostructures with the use of an effective temporary carrier is proposed. The method allows the process to be performed almost with no risk of heterostructure fracture, thinning of the Ge junction down to several tens of micrometers (or even several micrometers), significant enhancement of the yield of good structures, and also convenient and reliable transfer of thinned solar cells to an arbitrary light and flexible substrate. Such a technology offers a possibility of creating high-efficiency thin and light solar cells for space vehicles on the basis of mass-produced AIIIBV/Ge heterostructures.

Direct and Dry Deposited Single-Walled Carbon Nanotube Films Doped with MoO(x) as Electron-Blocking Transparent Electrodes for Flexible Organic Solar Cells.

PubMed

Jeon, Il; Cui, Kehang; Chiba, Takaaki; Anisimov, Anton; Nasibulin, Albert G; Kauppinen, Esko I; Maruyama, Shigeo; Matsuo, Yutaka

2015-07-01

Organic solar cells have been regarded as a promising electrical energy source. Transparent and conductive carbon nanotube film offers an alternative to commonly used ITO in photovoltaics with superior flexibility. This communication reports carbon nanotube-based indium-free organic solar cells and their flexible application. Direct and dry deposited carbon nanotube film doped with MoO(x) functions as an electron-blocking transparent electrode, and its performance is enhanced further by overcoating with PSS. The single-walled carbon nanotube organic solar cell in this work shows a power conversion efficiency of 6.04%. This value is 83% of the leading ITO-based device performance (7.48%). Flexible application shows 3.91% efficiency and is capable of withstanding a severe cyclic flex test.

Thermally Deposited Palladium-Tungsten Carbide and Platinum-Tungsten Carbide Counter Electrodes for a High Performance Dye-Sensitized Solar Cell Based on Organic T-/T₂ Electrolyte.

PubMed

Towannang, Madsakorn; Thiangkaew, Anongnad; Maiaugree, Wasan; Ratchaphonsaenwong, Kunthaya; Jarernboon, Wirat; Pimanpang, Samuk; Amornkitbamrung, Vittaya

2018-02-01

Tungsten carbide (WC) particles (~1 μm) were dispersed in DI water and dropped onto conductive glass. The resulting WC films were used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of the WC DSSC based on the organic thiolate/disulfide (T-/T2) electrolyte was ~0.78%. The cell efficiency was greatly improved after decorating palladium (Pd) or platinum (Pt) nanoparticles on WC particles with a promising efficiency of ~2.15% for Pd-WC DSSC and ~4.62% for Pt-WC DSSC. The efficiency improvement of the composited (Pd-WC and Pt-WC) cells is attributed to co-functioning catalysts, the large electrode interfacial area and a low charge-transfer resistance at the electrolyte/counter electrode interface.

Automated electrotransformation of Escherichia coli on a digital microfluidic platform using bioactivated magnetic beads.

PubMed

Moore, J A; Nemat-Gorgani, M; Madison, A C; Sandahl, M A; Punnamaraju, S; Eckhardt, A E; Pollack, M G; Vigneault, F; Church, G M; Fair, R B; Horowitz, M A; Griffin, P B

2017-01-01

This paper reports on the use of a digital microfluidic platform to perform multiplex automated genetic engineering (MAGE) cycles on droplets containing Escherichia coli cells. Bioactivated magnetic beads were employed for cell binding, washing, and media exchange in the preparation of electrocompetent cells in the electrowetting-on-dieletric (EWoD) platform. On-cartridge electroporation was used to deliver oligonucleotides into the cells. In addition to the optimization of a magnetic bead-based benchtop protocol for generating and transforming electrocompetent E. coli cells, we report on the implementation of this protocol in a fully automated digital microfluidic platform. Bead-based media exchange and electroporation pulse conditions were optimized on benchtop for transformation frequency to provide initial parameters for microfluidic device trials. Benchtop experiments comparing electrotransformation of free and bead-bound cells are presented. Our results suggest that dielectric shielding intrinsic to bead-bound cells significantly reduces electroporation field exposure efficiency. However, high transformation frequency can be maintained in the presence of magnetic beads through the application of more intense electroporation pulses. As a proof of concept, MAGE cycles were successfully performed on a commercial EWoD cartridge using variations of the optimal magnetic bead-based preparation procedure and pulse conditions determined by the benchtop results. Transformation frequencies up to 22% were achieved on benchtop; this frequency was matched within 1% (21%) by MAGE cycles on the microfluidic device. However, typical frequencies on the device remain lower, averaging 9% with a standard deviation of 9%. The presented results demonstrate the potential of digital microfluidics to perform complex and automated genetic engineering protocols.

Automated electrotransformation of Escherichia coli on a digital microfluidic platform using bioactivated magnetic beads

PubMed Central

Moore, J. A.; Nemat-Gorgani, M.; Madison, A. C.; Punnamaraju, S.; Eckhardt, A. E.; Pollack, M. G.; Church, G. M.; Fair, R. B.; Horowitz, M. A.; Griffin, P. B.

2017-01-01

This paper reports on the use of a digital microfluidic platform to perform multiplex automated genetic engineering (MAGE) cycles on droplets containing Escherichia coli cells. Bioactivated magnetic beads were employed for cell binding, washing, and media exchange in the preparation of electrocompetent cells in the electrowetting-on-dieletric (EWoD) platform. On-cartridge electroporation was used to deliver oligonucleotides into the cells. In addition to the optimization of a magnetic bead-based benchtop protocol for generating and transforming electrocompetent E. coli cells, we report on the implementation of this protocol in a fully automated digital microfluidic platform. Bead-based media exchange and electroporation pulse conditions were optimized on benchtop for transformation frequency to provide initial parameters for microfluidic device trials. Benchtop experiments comparing electrotransformation of free and bead-bound cells are presented. Our results suggest that dielectric shielding intrinsic to bead-bound cells significantly reduces electroporation field exposure efficiency. However, high transformation frequency can be maintained in the presence of magnetic beads through the application of more intense electroporation pulses. As a proof of concept, MAGE cycles were successfully performed on a commercial EWoD cartridge using variations of the optimal magnetic bead-based preparation procedure and pulse conditions determined by the benchtop results. Transformation frequencies up to 22% were achieved on benchtop; this frequency was matched within 1% (21%) by MAGE cycles on the microfluidic device. However, typical frequencies on the device remain lower, averaging 9% with a standard deviation of 9%. The presented results demonstrate the potential of digital microfluidics to perform complex and automated genetic engineering protocols. PMID:28191268

High-performance Förster resonance energy transfer (FRET)-based dye-sensitized solar cells: rational design of quantum dots for wide solar-spectrum utilization.

PubMed

Lee, Eunwoo; Kim, Chanhoi; Jang, Jyongsik

2013-07-29

High-performance Förster resonance energy transfer (FRET)-based dye-sensitized solar cells (DSSCs) have been successfully fabricated through the optimized design of a CdSe/CdS quantum-dot (QD) donor and a dye acceptor. This simple approach enables quantum dots and dyes to simultaneously utilize the wide solar spectrum, thereby resulting in high conversion efficiency over a wide wavelength range. In addition, major parameters that affect the FRET interaction between donor and acceptor have been investigated including the fluorescent emission spectrum of QD, and the content of deposited QDs into the TiO2 matrix. By judicious control of these parameters, the FRET interaction can be readily optimized for high photovoltaic performance. In addition, the as-synthesized water-soluble quantum dots were highly dispersed in a nanoporous TiO2 matrix, thereby resulting in excellent contact between donors and acceptors. Importantly, high-performance FRET-based DSSCs can be prepared without any infrared (IR) dye synthetic procedures. This novel strategy offers great potential for applications of dye-sensitized solar cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory.

PubMed

Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

2015-11-19

The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells.

Performance of OSC's initial Amtec generator design, and comparison with JPL's Europa Orbiter goals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schock, A.; Noravian, H.; Or, C.

1998-07-01

The procedure for the analysis (with overpotential correction) of multitube AMTEC (Alkali Metal Thermal-to-Electrical Conversion) cells described in Paper IECEC 98-243 was applied to a wide range of multicell radioisotope space power systems. System design options consisting of one or two generators, each with 2, 3, or 4 stacked GPHS (General Purpose Heat Source) modules, identical to those used on previous NASA missions, were analyzed and performance-mapped. The initial generators analyzed by OSC had 8 AMTEC cells on each end of the heat source stack, with five beta-alumina solid electrolyte (BASE) tubes per cell. The heat source and converters inmore » the Orbital generator designs are embedded in a thermal insulation system consisting of Min-K fibrous insulation surrounded by graded-length molybdenum multifoils. Detailed analyses in previous Orbital studies found that such an insulation system could reduce extraneous heat losses to about 10%. For the above design options, the present paper presents the system mass and performance (i.e., the EOM system efficiency and power output and the BOM evaporator and clad temperatures) for a wide range of heat inputs and load voltages, and compares the results with JPL's preliminary goals for the Europa Orbiter mission to be launched in November 2003. The analytical results showed that the initial 16-cell generator designs resulted in either excessive evaporator and clad temperatures and/or insufficient power outputs to meet the JPL-specified mission goals. The computed performance of modified OSC generators with different numbers of AMTEC cells, cell diameters, cell lengths, cell materials, BASE tube lengths, and number of tubes per cell are described in Paper IECEC.98.245 in these proceedings.« less

Development of high efficiency solar cells on silicon web

NASA Technical Reports Server (NTRS)

Rohatgi, A.; Meier, D. L.; Campbell, R. B.; Schmidt, D. N.; Rai-Choudhury, P.

1984-01-01

Web base material is being improved with a goal toward obtaining solar cell efficiencies in excess of 18% (AM1). Carrier loss mechanisms in web silicon was investigated, techniques were developed to reduce carrier recombination in the web, and web cells were fabricated using effective surface passivation. The effect of stress on web cell performance was also investigated.

Novel chemistries and materials for grid-scale energy storage: Quinones and halogen catalysis

NASA Astrophysics Data System (ADS)

Huskinson, Brian Thomas

In this work I describe various approaches to electrochemical energy storage at the grid-scale. Chapter 1 provides an introduction to energy storage and an overview of the history and development of flow batteries. Chapter 2 describes work on the hydrogen-chlorine regenerative fuel cell, detailing its development and the record-breaking performance of the device. Chapter 3 dives into catalyst materials for such a fuel cell, focusing on ruthenium oxide based alloys to be used as chlorine redox catalysts. Chapter 4 introduces and details the development of a performance model for a hydrogen-bromine cell. Chapter 5 delves into the more recent work I have done, switching to applications of quinone chemistries in flow batteries. It focuses on the pairing of one particular quinone (2,7-anthraquinone disulfonic acid) with bromine, and highlights the promising performance characteristics of a device based on this type of chemistry.

High-Performance Flexible Perovskite Solar Cells on Ultrathin Glass: Implications of the TCO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Benjia; Miller, Elisa M.; Christians, Jeffrey A.

For halide perovskite solar cells (PSCs) to fulfill their vast potential for combining low-cost, high efficiency, and high throughput production they must be scaled using a truly transformative method, such as roll-to-roll processing. Bringing this reality closer to fruition, the present work demonstrates flexible perovskite solar cells with 18.1% power conversion efficiency on flexible Willow Glass substrates. Here, we highlight the importance of the transparent conductive oxide (TCO) layers on device performance by studying various TCOs. And while tin-doped indium oxide (ITO) and indium zinc oxide (IZO) based PSC devices demonstrate high photovoltaic performances, aluminum-doped zinc oxide (AZO) based devicesmore » underperformed in all device parameters. Analysis of X-ray photoemission spectroscopy data shows that the stoichiometry of the perovskite film surface changes dramatically when it is fabricated on AZO, demonstrating the importance of the substrate in perovskite film formation.« less

High-Performance Flexible Perovskite Solar Cells on Ultrathin Glass: Implications of the TCO

DOE PAGES

Dou, Benjia; Miller, Elisa M.; Christians, Jeffrey A.; ...

2017-09-27

For halide perovskite solar cells (PSCs) to fulfill their vast potential for combining low-cost, high efficiency, and high throughput production they must be scaled using a truly transformative method, such as roll-to-roll processing. Bringing this reality closer to fruition, the present work demonstrates flexible perovskite solar cells with 18.1% power conversion efficiency on flexible Willow Glass substrates. Here, we highlight the importance of the transparent conductive oxide (TCO) layers on device performance by studying various TCOs. And while tin-doped indium oxide (ITO) and indium zinc oxide (IZO) based PSC devices demonstrate high photovoltaic performances, aluminum-doped zinc oxide (AZO) based devicesmore » underperformed in all device parameters. Analysis of X-ray photoemission spectroscopy data shows that the stoichiometry of the perovskite film surface changes dramatically when it is fabricated on AZO, demonstrating the importance of the substrate in perovskite film formation.« less

Evaluation and Testing of Commercially-Available Carbon Nanotubes as Negative Electrodes for Lithium Ion Cells

NASA Technical Reports Server (NTRS)

Britton, Doris L.

2007-01-01

Rechargeable lithium ion (Li-ion) battery technology offers significant performance advantages over the nickel-based technologies used for energy storage for the majority of NASA's missions. Specifically Li-ion technology offers a threefold to fourfold increase in gravimetric and volumetric energy densities and produces voltages in excess of three times the value of typical nickel-based battery systems. As part of the Advanced Battery Technology program at NASA Glenn Research Center (GRC), a program on the evaluation of anodes for Li-ion cells and batteries was conducted. This study focused on the feasibility of using carbon nanotubes as anodes in Li-Ion cells. Candidate materials from multiple sources were evaluated. Their performance was compared to a standard anode comprised of mesocarbon microbeads. In all cases, the standard MCMB electrode exhibited superior performance. The details and results of the study are presented.

Development of coin-type cell and engineering of its compartments for rechargeable seawater batteries

NASA Astrophysics Data System (ADS)

Han, Jinhyup; Hwang, Soo Min; Go, Wooseok; Senthilkumar, S. T.; Jeon, Donghoon; Kim, Youngsik

2018-01-01

Cell design and optimization of the components, including active materials and passive components, play an important role in constructing robust, high-performance rechargeable batteries. Seawater batteries, which utilize earth-abundant and natural seawater as the active material in an open-structured cathode, require a new platform for building and testing the cells other than typical Li-ion coin-type or pouch-type cells. Herein, we present new findings based on our optimized cell. Engineering the cathode components-improving the wettability of cathode current collector and seawater catholyte flow-improves the battery performance (voltage efficiency). Optimizing the cell component and design is the key to identifying the electrochemical processes and reactions of active materials. Hence, the outcome of this research can provide a systematic study of potentially active materials used in seawater batteries and their effectiveness on the electrochemical performance.

Recycling Perovskite Solar Cells To Avoid Lead Waste.

PubMed

Binek, Andreas; Petrus, Michiel L; Huber, Niklas; Bristow, Helen; Hu, Yinghong; Bein, Thomas; Docampo, Pablo

2016-05-25

Methylammonium lead iodide (MAPbI3) perovskite based solar cells have recently emerged as a serious competitor for large scale and low-cost photovoltaic technologies. However, since these solar cells contain toxic lead, a sustainable procedure for handling the cells after their operational lifetime is required to prevent exposure of the environment to lead and to comply with international electronic waste disposal regulations. Herein, we report a procedure to remove every layer of the solar cells separately, which gives the possibility to selectively isolate the different materials. Besides isolating the toxic lead iodide in high yield, we show that the PbI2 can be reused for the preparation of new solar cells with comparable performance and in this way avoid lead waste. Furthermore, we show that the most expensive part of the solar cell, the conductive glass (FTO), can be reused several times without any reduction in the performance of the devices. With our simple recycling procedure, we address both the risk of contamination and the waste disposal of perovskite based solar cells while further reducing the cost of the system. This brings perovskite solar cells one step closer to their introduction into commercial systems.

Properties of skin stem cells and their potential clinical applications in modern dermatology.

PubMed

Niezgoda, Anna; Niezgoda, Piotr; Nowowiejska, Laura; Białecka, Agnieszka; Męcińska-Jundziłł, Kaja; Adamska, Urszula; Czajkowski, Rafał

2017-06-01

Stem cells play an important role in medical science, and scientists are investing large sums in order to perform sophisticated studies designed to establish potential clinical applications of stem cells. Growing experience has enabled researchers to determine the precise nature of stem cell division. Although the properties of this particular population of cells have been known and used for some time, mainly with regards to bone marrow-derived mesenchymal stem cell transplantation, we now face a significant challenge in implementing the practical use of skin-derived precursors, making it possible to avoid the necessity for patients to undergo invasive procedures in order to obtain stem cells from bone marrow. Multiple trials have so far been performed, bringing hope for the treatment of disorders previously considered untreatable. Patients suffering from a number of dermatological diseases, including malignant melanoma, systemic lupus erythematosus, vitiligo, alopecia or junctional epidermolysis bullosa, may benefit from treatment based on stem cells. The aim of this review is to summarize available data on stem cells and their potential applications in the treatment of dermatological disorders. The work described is based on data published up to the end of September 2016.

Development of high-efficiency solar cells on silicon web

NASA Technical Reports Server (NTRS)

Meier, D. L.; Greggi, J.; Okeeffe, T. W.; Rai-Choudhury, P.

1986-01-01

Work was performed to improve web base material with a goal of obtaining solar cell efficiencies in excess of 18% (AM1). Efforts in this program are directed toward identifying carrier loss mechanisms in web silicon, eliminating or reducing these mechanisms, designing a high efficiency cell structure with the aid of numerical models, and fabricating high efficiency web solar cells. Fabrication techniques must preserve or enhance carrier lifetime in the bulk of the cell and minimize recombination of carriers at the external surfaces. Three completed cells were viewed by cross-sectional transmission electron microscopy (TEM) in order to investigate further the relation between structural defects and electrical performance of web cells. Consistent with past TEM examinations, the cell with the highest efficiency (15.0%) had no dislocations but did have 11 twin planes.

Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Kang, Tae-Woon; Noh, Yong-Jin; Yun, Jin-Mun; Yang, Si-Young; Yang, Yong-Eon; Lee, Hae-Seong; Na, Seok-In

2015-06-01

This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs.

Enhanced photovoltaic performance and stability with a new type of hollow 3D perovskite {en}FASnI 3

DOE PAGES

Ke, Weijun; Stoumpos, Constantinos C.; Zhu, Menghua; ...

2017-08-30

Perovskite solar cells have revolutionized the fabrication of solution-processable solar cells. The presence of lead in the devices makes this technology less attractive, and alternative metals in perovskites are being researched as suitable alternatives. We demonstrate a new type of tin-based perovskite absorber that incorporates both ethylenediammonium (en) and formamidinium (FA), forming new materials of the type {en}FASnI 3. The three-dimensional ASnI 3 structure is stable only with methylammonium, FA, and Cs cations, and the bandgap can be tuned with solid solutions, such as ASnI 3-xBr x. We show that en can serve as a new A cation capable ofmore » achieving marked increases in the bandgap without the need for solid solutions. The en introduces a new bandgap tuning mechanism that arises from massive Schottky style defects. In addition, incorporation of the en cation in the structure markedly increases the air stability and improves the photoelectric properties of the tin-based perovskite absorbers. Our best-performing {en}FASnI 3 solar cell has the highest efficiency of 7.14%, which is achieved for a lead-free perovskite cell, and retains 96% of its initial efficiency after aging over 1000 hours with encapsulation. Our results introduce a new approach for improving the performance and stability of tin-based, lead-free perovskite solar cells.« less

Enhanced photovoltaic performance and stability with a new type of hollow 3D perovskite {en}FASnI 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ke, Weijun; Stoumpos, Constantinos C.; Zhu, Menghua

Perovskite solar cells have revolutionized the fabrication of solution-processable solar cells. The presence of lead in the devices makes this technology less attractive, and alternative metals in perovskites are being researched as suitable alternatives. We demonstrate a new type of tin-based perovskite absorber that incorporates both ethylenediammonium (en) and formamidinium (FA), forming new materials of the type {en}FASnI 3. The three-dimensional ASnI 3 structure is stable only with methylammonium, FA, and Cs cations, and the bandgap can be tuned with solid solutions, such as ASnI 3-xBr x. We show that en can serve as a new A cation capable ofmore » achieving marked increases in the bandgap without the need for solid solutions. The en introduces a new bandgap tuning mechanism that arises from massive Schottky style defects. In addition, incorporation of the en cation in the structure markedly increases the air stability and improves the photoelectric properties of the tin-based perovskite absorbers. Our best-performing {en}FASnI 3 solar cell has the highest efficiency of 7.14%, which is achieved for a lead-free perovskite cell, and retains 96% of its initial efficiency after aging over 1000 hours with encapsulation. Our results introduce a new approach for improving the performance and stability of tin-based, lead-free perovskite solar cells.« less

Enhanced photovoltaic performance and stability with a new type of hollow 3D perovskite {en}FASnI3

PubMed Central

Ke, Weijun; Stoumpos, Constantinos C.; Zhu, Menghua; Mao, Lingling; Spanopoulos, Ioannis; Liu, Jian; Kontsevoi, Oleg Y.; Chen, Michelle; Sarma, Debajit; Zhang, Yongbo; Wasielewski, Michael R.; Kanatzidis, Mercouri G.

2017-01-01

Perovskite solar cells have revolutionized the fabrication of solution-processable solar cells. The presence of lead in the devices makes this technology less attractive, and alternative metals in perovskites are being researched as suitable alternatives. We demonstrate a new type of tin-based perovskite absorber that incorporates both ethylenediammonium (en) and formamidinium (FA), forming new materials of the type {en}FASnI3. The three-dimensional ASnI3 structure is stable only with methylammonium, FA, and Cs cations, and the bandgap can be tuned with solid solutions, such as ASnI3−xBrx. We show that en can serve as a new A cation capable of achieving marked increases in the bandgap without the need for solid solutions. The en introduces a new bandgap tuning mechanism that arises from massive Schottky style defects. In addition, incorporation of the en cation in the structure markedly increases the air stability and improves the photoelectric properties of the tin-based perovskite absorbers. Our best-performing {en}FASnI3 solar cell has the highest efficiency of 7.14%, which is achieved for a lead-free perovskite cell, and retains 96% of its initial efficiency after aging over 1000 hours with encapsulation. Our results introduce a new approach for improving the performance and stability of tin-based, lead-free perovskite solar cells. PMID:28875173

Novel flowcytometry-based approach of malignant cell detection in body fluids using an automated hematology analyzer

PubMed Central

Tabe, Yoko; Takemura, Hiroyuki; Kimura, Konobu; Takahashi, Toshihiro; Yang, Haeun; Tsuchiya, Koji; Konishi, Aya; Uchihashi, Kinya; Horii, Takashi; Ohsaka, Akimichi

2018-01-01

Morphological microscopic examinations of nucleated cells in body fluid (BF) samples are performed to screen malignancy. However, the morphological differentiation is time-consuming and labor-intensive. This study aimed to develop a new flowcytometry-based gating analysis mode “XN-BF gating algorithm” to detect malignant cells using an automated hematology analyzer, Sysmex XN-1000. XN-BF mode was equipped with WDF white blood cell (WBC) differential channel. We added two algorithms to the WDF channel: Rule 1 detects larger and clumped cell signals compared to the leukocytes, targeting the clustered malignant cells; Rule 2 detects middle sized mononuclear cells containing less granules than neutrophils with similar fluorescence signal to monocytes, targeting hematological malignant cells and solid tumor cells. BF samples that meet, at least, one rule were detected as malignant. To evaluate this novel gating algorithm, 92 various BF samples were collected. Manual microscopic differentiation with the May-Grunwald Giemsa stain and WBC count with hemocytometer were also performed. The performance of these three methods were evaluated by comparing with the cytological diagnosis. The XN-BF gating algorithm achieved sensitivity of 63.0% and specificity of 87.8% with 68.0% for positive predictive value and 85.1% for negative predictive value in detecting malignant-cell positive samples. Manual microscopic WBC differentiation and WBC count demonstrated 70.4% and 66.7% of sensitivities, and 96.9% and 92.3% of specificities, respectively. The XN-BF gating algorithm can be a feasible tool in hematology laboratories for prompt screening of malignant cells in various BF samples. PMID:29425230

Novel flowcytometry-based approach of malignant cell detection in body fluids using an automated hematology analyzer.

PubMed

Ai, Tomohiko; Tabe, Yoko; Takemura, Hiroyuki; Kimura, Konobu; Takahashi, Toshihiro; Yang, Haeun; Tsuchiya, Koji; Konishi, Aya; Uchihashi, Kinya; Horii, Takashi; Ohsaka, Akimichi

2018-01-01

Morphological microscopic examinations of nucleated cells in body fluid (BF) samples are performed to screen malignancy. However, the morphological differentiation is time-consuming and labor-intensive. This study aimed to develop a new flowcytometry-based gating analysis mode "XN-BF gating algorithm" to detect malignant cells using an automated hematology analyzer, Sysmex XN-1000. XN-BF mode was equipped with WDF white blood cell (WBC) differential channel. We added two algorithms to the WDF channel: Rule 1 detects larger and clumped cell signals compared to the leukocytes, targeting the clustered malignant cells; Rule 2 detects middle sized mononuclear cells containing less granules than neutrophils with similar fluorescence signal to monocytes, targeting hematological malignant cells and solid tumor cells. BF samples that meet, at least, one rule were detected as malignant. To evaluate this novel gating algorithm, 92 various BF samples were collected. Manual microscopic differentiation with the May-Grunwald Giemsa stain and WBC count with hemocytometer were also performed. The performance of these three methods were evaluated by comparing with the cytological diagnosis. The XN-BF gating algorithm achieved sensitivity of 63.0% and specificity of 87.8% with 68.0% for positive predictive value and 85.1% for negative predictive value in detecting malignant-cell positive samples. Manual microscopic WBC differentiation and WBC count demonstrated 70.4% and 66.7% of sensitivities, and 96.9% and 92.3% of specificities, respectively. The XN-BF gating algorithm can be a feasible tool in hematology laboratories for prompt screening of malignant cells in various BF samples.

Mixed Sn-Ge Perovskite for Enhanced Perovskite Solar Cell Performance in Air.

PubMed

Ito, Nozomi; Kamarudin, Muhammad Akmal; Hirotani, Daisuke; Zhang, Yaohong; Shen, Qing; Ogomi, Yuhei; Iikubo, Satoshi; Minemoto, Takashi; Yoshino, Kenji; Hayase, Shuzi

2018-04-05

Lead-based perovskite solar cells have gained ground in recent years, showing efficiency as high as 20%, which is on par with that of silicon solar cells. However, the toxicity of lead makes it a nonideal candidate for use in solar cells. Alternatively, tin-based perovskites have been proposed because of their nontoxic nature and abundance. Unfortunately, these solar cells suffer from low efficiency and stability. Here, we propose a new type of perovskite material based on mixed tin and germanium. The material showed a band gap around 1.4-1.5 eV as measured from photoacoustic spectroscopy, which is ideal from the perspective of solar cells. In a solar cell device with inverted planar structure, pure tin perovskite solar cell showed a moderate efficiency of 3.31%. With 5% doping of germanium into the perovskite, the efficiency improved up to 4.48% (6.90% after 72 h) when measured in air without encapsulation.

Enhanced performance of a structured cyclo olefin copolymer-based amorphous silicon solar cell

NASA Astrophysics Data System (ADS)

Zhan, Xinghua; Chen, Fei; Gao, Mengyu; Tie, Shengnian; Gao, Wei

2017-07-01

The submicron array was fabricated onto a cyclo olefin copolymer (COC) film by a hot embossing method. An amorphous silicon p-i-n junction and transparent conductive layers were then deposited onto it through a plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering. The efficiency of the fabricated COC-based solar cell was measured and the result demonstrated 18.6% increase of the solar cell efficiency when compared to the sample without array structure. The imprinted polymer solar cells with submicron array indeed increase their efficiency.

Progress towards computer simulation of NiH2 battery performance over life

NASA Technical Reports Server (NTRS)

Zimmerman, Albert H.; Quinzio, M. V.

1995-01-01

The long-term performance of rechargeable battery cells has traditionally been verified through life-testing, a procedure that generally requires significant commitments of funding and test resources. In the situation of nickel hydrogen battery cells, which have the capability of providing extremely long cycle life, the time and cost required to conduct even accelerated testing has become a serious impediment to transitioning technology improvements into spacecraft applications. The utilization of computer simulations to indicate the changes in performance to be expected in response to design or operating changes in nickel hydrogen cells is therefore a particularly attractive tool in advanced battery development, as well as for verifying performance in different applications. Computer-based simulations of the long-term performance of rechargeable battery cells have typically had very limited success in the past. There are a number of reasons for the lack in progress in this area. First, and probably most important, all battery cells are relatively complex electrochemical systems, in which performance is dictated by a large number of interacting physical and chemical processes. While the complexity alone is a significant part of the problem, in many instances the fundamental chemical and physical processes underlying long-term degradation and its effects on performance have not even been understood. Second, while specific chemical and physical changes within cell components have been associated with degradation, there has been no generalized simulation architecture that enables the chemical and physical structure (and changes therein) to be translated into cell performance. For the nickel hydrogen battery cell, our knowledge of the underlying reactions that control the performance of this cell has progressed to where it clearly is possible to model them. The recent development of a relative generalized cell modelling approach provides the framework for translating the chemical and physical structure of the components inside a cell into its performance characteristics over its entire cycle life. This report describes our approach to this task in terms of defining those processes deemed critical in controlling performance over life, and the model architecture required to translate the fundamental cell processes into performance profiles.

Simultaneous Measurement of Multiple Mechanical Properties of Single Cells Using AFM by Indentation and Vibration.

PubMed

Zhang, Chuang; Shi, Jialin; Wang, Wenxue; Xi, Ning; Wang, Yuechao; Liu, Lianqing

2017-12-01

The mechanical properties of cells, which are the main characteristics determining their physical performance and physiological functions, have been actively studied in the fields of cytobiology and biomedical engineering and for the development of medicines. In this study, an indentation-vibration-based method is proposed to simultaneously measure the mechanical properties of cells in situ, including cellular mass (m), elasticity (k), and viscosity (c). The proposed measurement method is implemented based on the principle of forced vibration stimulated by simple harmonic force using an atomic force microscope (AFM) system integrated with a piezoelectric transducer as the substrate vibrator. The corresponding theoretical model containing the three mechanical properties is derived and used to perform simulations and calculations. Living and fixed human embryonic kidney 293 (HEK 293) cells were subjected to indentation and vibration to measure and compare their mechanical parameters and verify the proposed approach. The results that the fixed sample cells are more viscous and elastic than the living sample cells and the measured mechanical properties of cell are consistent within, but not outside of the central region of the cell, are in accordance with the previous studies. This work provides an approach to simultaneous measurement of the multiple mechanical properties of single cells using an integrated AFM system based on the principle force vibration and thickness-corrected Hertz model. This study should contribute to progress in biomedical engineering, cytobiology, medicine, early diagnosis, specific therapy and cell-powered robots.

High-performance radial AMTEC cell design for ultra-high-power solar AMTEC systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendricks, T.J.; Huang, C.

1999-07-01

Alkali Metal Thermal to Electric Conversion (AMTEC) technology is rapidly maturing for potential application in ultra-high-power solar AMTEC systems required by potential future US Air Force (USAF) spacecraft missions in medium-earth and geosynchronous orbits (MEO and GEO). Solar thermal AMTEC power systems potentially have several important advantages over current solar photovoltaic power systems in ultra-high-power spacecraft applications for USAF MEO and GEO missions. This work presents key aspects of radial AMTEC cell design to achieve high cell performance in solar AMTEC systems delivering larger than 50 kW(e) to support high power USAF missions. These missions typically require AMTEC cell conversionmore » efficiency larger than 25%. A sophisticated design parameter methodology is described and demonstrated which establishes optimum design parameters in any radial cell design to satisfy high-power mission requirements. Specific relationships, which are distinct functions of cell temperatures and pressures, define critical dependencies between key cell design parameters, particularly the impact of parasitic thermal losses on Beta Alumina Solid Electrolyte (BASE) area requirements, voltage, number of BASE tubes, and system power production for both maximum power-per-BASE-area and optimum efficiency conditions. Finally, some high-level system tradeoffs are demonstrated using the design parameter methodology to establish high-power radial cell design requirements and philosophy. The discussion highlights how to incorporate this methodology with sophisticated SINDA/FLUINT AMTEC cell modeling capabilities to determine optimum radial AMTEC cell designs.« less

Pumps for microfluidic cell culture.

PubMed

Byun, Chang Kyu; Abi-Samra, Kameel; Cho, Yoon-Kyoung; Takayama, Shuichi

2014-02-01

In comparison to traditional in vitro cell culture in Petri dishes or well plates, cell culture in microfluidic-based devices enables better control over chemical and physical environments, higher levels of experimental automation, and a reduction in experimental materials. Over the past decade, the advantages associated with cell culturing in microfluidic-based platforms have garnered significant interest and have led to a plethora of studies for high throughput cell assays, organs-on-a-chip applications, temporal signaling studies, and cell sorting. A clear concern for performing cell culture in microfluidic-based devices is deciding on a technique to deliver and pump media to cells that are encased in a microfluidic device. In this review, we summarize recent advances in pumping techniques for microfluidic cell culture and discuss their advantages and possible drawbacks. The ultimate goal of our review is to distill the large body of information available related to pumps for microfluidic cell culture in an effort to assist current and potential users of microfluidic-based devices for advanced in vitro cellular studies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell module and fuel conditioner development

NASA Technical Reports Server (NTRS)

Feret, J. M.

1982-01-01

The efforts performed to develop a phosphoric acid fuel cell (PAFC) stack design having a 10 kW power rating for operation at higher than atmospheric pressure based on the existing Mark II design configuration are described. The work involves: (1) Performance of pertinent functional analysis, trade studies and thermodynamic cycle analysis for requirements definition and system operating parameter selection purposes, (2) characterization of fuel cell materials and components, and performance testing and evaluation of the repeating electrode components, (3) establishment of the state-of-the-art manufacturing technology for all fuel cell components at Westinghouse and the fabrication of short stacks of various sites, and (4) development of a 10 kW PAFC stack design for higher pressure operation utilizing the top down systems engineering approach.

Drug and bioactive molecule screening based on a bioelectrical impedance cell culture platform

PubMed Central

Ramasamy, Sakthivel; Bennet, Devasier; Kim, Sanghyo

2014-01-01

This review will present a brief discussion on the recent advancements of bioelectrical impedance cell-based biosensors, especially the electric cell-substrate impedance sensing (ECIS) system for screening of various bioactive molecules. The different technical integrations of various chip types, working principles, measurement systems, and applications for drug targeting of molecules in cells are highlighted in this paper. Screening of bioactive molecules based on electric cell-substrate impedance sensing is a trial-and-error process toward the development of therapeutically active agents for drug discovery and therapeutics. In general, bioactive molecule screening can be used to identify active molecular targets for various diseases and toxicity at the cellular level with nanoscale resolution. In the innovation and screening of new drugs or bioactive molecules, the activeness, the efficacy of the compound, and safety in biological systems are the main concerns on which determination of drug candidates is based. Further, drug discovery and screening of compounds are often performed in cell-based test systems in order to reduce costs and save time. Moreover, this system can provide more relevant results in in vivo studies, as well as high-throughput drug screening for various diseases during the early stages of drug discovery. Recently, MEMS technologies and integration with image detection techniques have been employed successfully. These new technologies and their possible ongoing transformations are addressed. Select reports are outlined, and not all the work that has been performed in the field of drug screening and development is covered. PMID:25525360

Employing overlayers to improve the performance of Cu 2BaSnS 4 thin film based photoelectrochemical water reduction devices

DOE PAGES

Ge, Jie; Roland, Paul J.; Koirala, Prakash; ...

2017-01-19

Earth-abundant copper-barium-thiostannate Cu 2BaSnS 4 (CBTS)-based thin films have recently been reported to exhibit the optoelectronic and defect properties suitable as absorbers for photoelectrochemical (PEC) water splitting and the top cell of tandem photovoltaic solar cells. However, the photocurrents of CBTS-based PEC devices are still much lower than the theoretical value, partially due to ineffective charge collection at CBTS/water interface and instability of CBTS in electrolytes. Here, we report on overcoming these issues by employing overlayer engineering. We find that CdS/ZnO/TiO 2 overlayers can significant-ly improve the PEC performance, achieving saturated cathodic photocurrents up to 7.8 mA cm -2 atmore » the potential of -0.10 V versus reversible hydrogen electrode (RHE) in a neutral electrolyte solution, which is much higher than the best bare CBTS film attaining a photocurrent of 4.8 mA cm -2 at the potential of -0.2 V versus RHE. Finally, our results suggest a viable approach for improving the performance of CBTS-based PEC cells.« less

Development of high-performance GaInAsP solar cells for tandem solar cell applications

NASA Technical Reports Server (NTRS)

Wanlass, M. W.; Ward, J. S.; Gessert, T. A.; Emery, K. A.; Horner, G. S.

1990-01-01

Recent results in the development of high-efficiency, low-bandgap GaInAsP solar cells epitaxially grown and lattice matched on InP substrates are presented. Such cells are intended to be used as optimum bottom cell components in tandem solar cells. Assuming that a GaAs-based top cell is used, computer simulation of the potential bottom cell performance as a function of the cell bandgap and incident spectrum indicates that two particular alloys are desirable: Ga0.47In0.53As (Eg = 0.75 eV) for space applications and Ga0.25In0.75As0.54P0.46 (Eg = 0.95 eV) for terrestrial applications. In each of these materials, solar cells with new record-level efficiencies have been fabricated. The efficiency boost available to tandem configurations from these low-bandgap cells is discussed.

Electrolyte formulations

DOEpatents

Zhu, Ye; Strand, Deidre; Cheng, Gang

2018-05-29

An electrochemical cell including a silicon-based anode and an electrolyte, where the electrolyte is formulated to contain solvents having cyclic sulfone or cyclic sulfite chemical structure. Specific additional solvent and salt combinations yield superior performance in these electrochemical cells.

AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack

NASA Technical Reports Server (NTRS)

Dinetta, L. C.; Hannon, M. H.; Mcneely, J. B.; Barnett, A. M.

1991-01-01

The AstroPower self-supporting, transparent AlGaAs top solar cell can be stacked upon any well-developed bottom solar cell for improved system performance. This is an approach to improve the performance and scale of space photovoltaic power systems. Mechanically stacked tandem solar cell concentrator systems based on the AlGaAs top concentrator solar cell can provide near term efficiencies of 36 percent (AMO, 100x). Possible tandem stack efficiencies greater than 38 percent (100x, AMO) are feasible with a careful selection of materials. In a three solar cell stack, system efficiencies exceed 41 percent (100x, AMO). These device results demonstrate a practical solution for a state-of-the-art top solar cell for attachment to an existing, well-developed solar cell.

Comparison of parameter-adapted segmentation methods for fluorescence micrographs.

PubMed

Held, Christian; Palmisano, Ralf; Häberle, Lothar; Hensel, Michael; Wittenberg, Thomas

2011-11-01

Interpreting images from fluorescence microscopy is often a time-consuming task with poor reproducibility. Various image processing routines that can help investigators evaluate the images are therefore useful. The critical aspect for a reliable automatic image analysis system is a robust segmentation algorithm that can perform accurate segmentation for different cell types. In this study, several image segmentation methods were therefore compared and evaluated in order to identify the most appropriate segmentation schemes that are usable with little new parameterization and robustly with different types of fluorescence-stained cells for various biological and biomedical tasks. The study investigated, compared, and enhanced four different methods for segmentation of cultured epithelial cells. The maximum-intensity linking (MIL) method, an improved MIL, a watershed method, and an improved watershed method based on morphological reconstruction were used. Three manually annotated datasets consisting of 261, 817, and 1,333 HeLa or L929 cells were used to compare the different algorithms. The comparisons and evaluations showed that the segmentation performance of methods based on the watershed transform was significantly superior to the performance of the MIL method. The results also indicate that using morphological opening by reconstruction can improve the segmentation of cells stained with a marker that exhibits the dotted surface of cells. Copyright © 2011 International Society for Advancement of Cytometry.

Poly(terphenylene) Anion Exchange Membranes: The Effect of Backbone Structure on Morphology and Membrane Property

DOE PAGES

Lee, Woo-Hyung; Park, Eun Joo; Han, Junyoung; ...

2017-05-05

A new design concept for ion-conducting polymers in anion exchange membranes (AEMs) fuel cells is proposed based on structural studies and conformational analysis of polymers and their effect on the properties of AEMs. Thermally, chemically, and mechanically stable terphenyl-based polymers with pendant quaternary ammonium alkyl groups were synthesized to investigate the effect of varying the arrangement of the polymer backbone and cation-tethered alkyl chains. The results demonstrate that the microstructure and morphology of these polymeric membranes significantly influence ion conductivity and fuel cell performance. Finally, the results of this study provide new insights that will guide the molecular design ofmore » polymer electrolyte materials to improve fuel cell performance.« less

High performance anode based on a partially fluorinated sulfonated polyether for direct methanol fuel cells operating at 130 °C

NASA Astrophysics Data System (ADS)

Mack, Florian; Gogel, Viktor; Jörissen, Ludwig; Kerres, Jochen

2014-06-01

Due to the disadvantages of the Nafion polymer for the application in the direct methanol fuel cell (DMFC) especial at temperatures above 100 °C several polymers of the hydrocarbon type have already been investigated as membranes and ionomers in the DMFC. Among them were nonfluorinated and partially fluorinated arylene main-chain hydrocarbon polymers. In previous work, sulfonated polysulfone (sPSU) has been applied as the proton-conductive binder in the anode of a DMFC, ending up in good and stable performance. In continuation of this work, in the study presented here a polymer was prepared by polycondensation of decafluorobiphenyl and bisphenol AF. The formed polymer was sulfonated after polycondensation by oleum and the obtained partially fluorinated sulfonated polyether (SFS) was used as the binder and proton conductor in a DMFC anode operating at a temperature of 130 °C. The SFS based anode with 5% as ionomer showed comparable performance for the methanol oxidation to Nafion based anodes and significant reduced performance degradation versus Nafion and sPSU based anodes on the Nafion 115 membrane. Membrane electrode assemblies (MEAs) with the SFS based anode showed drastically improved performance compared to MEAs with Nafion based anodes during operation with lower air pressure at the cathode.

Multi-modal porous microstructure for high temperature fuel cell application

NASA Astrophysics Data System (ADS)

Wejrzanowski, T.; Haj Ibrahim, S.; Cwieka, K.; Loeffler, M.; Milewski, J.; Zschech, E.; Lee, C.-G.

2018-01-01

In this study, the effect of microstructure of porous nickel electrode on the performance of high temperature fuel cell is investigated and presented based on a molten carbonate fuel cell (MCFC) cathode. The cathode materials are fabricated from slurry consisting of nickel powder and polymeric binder/solvent mixture, using the tape casting method. The final pore structure is shaped through modifying the slurry composition - with or without the addition of porogen(s). The manufactured materials are extensively characterized by various techniques involving: micro-computed tomography (micro-XCT), scanning electron microscopy (SEM), mercury porosimetry, BET and Archimedes method. Tomographic images are also analyzed and quantified to reveal the evolution of pore space due to nickel in situ oxidation to NiO, and infiltration by the electrolyte. Single-cell performance tests are carried out under MCFC operation conditions to estimate the performance of the manufactured materials. It is found that the multi-modal microstructure of MCFC cathode results in a significant enhancement of the power density generated by the reference cell. To give greater insight into the understanding of the effect of microstructure on the properties of the cathode, a model based on 3D tomography image transformation is proposed.

Na-ion batteries based on the inorganic BN nanocluster anodes: DFT studies.

PubMed

Nejati, K; Hosseinian, A; Bekhradnia, A; Vessally, E; Edjlali, L

2017-06-01

It has been recently indicated that the Li-ion batteries may be replaced by Na-ion batteries because of their low safety, high cost, and low-temperature performance, and lack of the Li mineral reserves. Here, using density functional theory calculations, we studied the potential application of B 12 N 12 nanoclusters as anode in Na-ion batteries. Our calculations indicate that the adsorption energy of Na + and Na are about -23.4 and -1.4kcal/mol, respectively, and the pristine BN cage to improve suffers from a low cell voltage (∼0.92V) as an anode in Na-ion batteries. We presented a strategy to increase the cell voltage and performance of Na-ion batteries. We showed that encapsulation of different halides (X=F - , Cl - , or Br - ) into BN cage significantly increases the cell voltage. By increasing the atomic number of X, the Gibbs free energy change of cell becomes more negative and the cell voltage is increased up to 3.93V. The results are discussed based on the structural, energetic, frontier molecular orbital, charge transfer and electronic properties and compared with the performance of other nanostructured anodes. Copyright © 2017 Elsevier Inc. All rights reserved.

An Efficient Amphiphilic-Type Triphenylamine-Based Organic Hole Transport Material for High-Performance and Ambient-Stable Dopant-Free Perovskite and Organic Solar Cells.

PubMed

Reddy, Saripally Sudhaker; Park, Ho-Yeol; Kwon, Haeun; Shin, Jongmoon; Kim, Chang-Su; Song, Myungkwan; Jin, Sung-Ho

2018-04-25

A new set of simply structured triphenylamine-based small molecules are synthesized and evaluated as dopant-free hole transporting materials (HTMs) for high-performance perovskite solar cells (PSCs) and bulk heterojunction inverted organic solar cells (BHJ IOSCs). Surprisingly, the new amphiphilic-type HTM-1 (with internal hydrophilic groups and peripheral hydrophobic alkyl tails) showed better compatibility and performance than the actual target molecule, that is, HTM-2 in PSCs and BHJ IOSCs. Importantly, the HTM-1-based dopant-free PSCs and BHJ IOSCs exhibited high power conversion efficiencies (PCEs) of 11.45 % and 8.34 %, respectively. These performances are superior and comparable to those of standard HTMs Spiro-OMeTAD (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate) in PSCs and BHJ IOSCs, respectively. The enhanced device performance of the HTM-1-based PSCs is ascribed to its strong affinity towards the perovskite, properly aligned energy levels with respect to the perovskite valence band, and excellent hole transporting behavior. In addition, the well-organized energy levels of the HTMs showed excellent compatibility in BHJ IOSCs. The new amphiphilic-type HTM-based photovoltaic devices also showed long-term air stability over 700 h. These promising results offer new and unexpected prospects for engineering the interface between the photoactive material and HTMs in PSCs and BHJ IOSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An assessment of alternative fuel cell designs for residential and commercial cogeneration

NASA Technical Reports Server (NTRS)

Wakefield, R. A.

1980-01-01

A comparative assessment of three fuel cell systems for application in different buildings and geographic locations is presented. The study was performed at the NASA Lewis Center and comprised the fuel cell design, performance in different conditions, and the economic parameters. Applications in multifamily housing, stores and hospitals were considered, with a load of 10kW-1 MW. Designs were traced through system sizing, simulation/evaluation, and reliability analysis, and a computer simulation based on a fourth-order representation of a generalized system was performed. The cells were all phosphoric acid type cells, and were found to be incompatible with gas/electric systems and more favorable economically than the gas/electric systems in hospital uses. The methodology used provided an optimized energy-use pattern and minimized back-up system turn-on.

Vertically aligned carbon nanotubes as anode and air-cathode in single chamber microbial fuel cells

NASA Astrophysics Data System (ADS)

Amade, R.; Moreno, H. A.; Hussain, S.; Vila-Costa, M.; Bertran, E.

2016-10-01

Electrode optimization in microbial fuel cells is a key issue to improve the power output and cell performance. Vertically aligned carbon nanotubes (VACNTs) grown on low cost stainless-steel mesh present an attractive approach to increase the cell performance while avoiding the use of expensive Pt-based materials. In comparison with non-aligned carbon nanotubes (NACNTs), VACNTs increase the oxygen reduction reaction taking place at the cathode by a factor of two. In addition, vertical alignment also increases the power density up to 2.5 times with respect to NACNTs. VACNTs grown at the anode can further improve the cell performance by increasing the electrode surface area and thus the electron transfer between bacteria and the electrode. The maximum power density obtained using VACNTs was 14 mW/m2 and 160 mV output voltage.

Intracellular probes for imaging oxygen concentration: how good are they?

NASA Astrophysics Data System (ADS)

Dmitriev, Ruslan I.; Papkovsky, Dmitri B.

2015-09-01

In the last decade a number of cell-permeable phosphorescence based probes for imaging of (intra)cellular oxygen (icO2) have been described. These small molecule, supramolecular and nanoparticle structures, although allowing analysis of hypoxia, local gradients and fluctuations in O2, responses to stimulation and drug treatment at sub-cellular level with high spatial and temporal resolution, differ significantly in their operational performance and applicability to different cell and tissue models. Here we discuss and compare these probes with respect to their staining efficiency, brightness, photostability, toxicity, cell specificity, compatibility with different cell and tissue models, and analytical performance. Merits and limitations of particular probes are highlighted and strategies for development of new high-performance O2 imaging probes defined. Key application areas in hypoxia research, stem cells, cancer biology and tissue physiology are also discussed.

Isolation of breast cancer and gastric cancer circulating tumor cells by use of an anti HER2-based microfluidic device.

PubMed

Galletti, Giuseppe; Sung, Matthew S; Vahdat, Linda T; Shah, Manish A; Santana, Steven M; Altavilla, Giuseppe; Kirby, Brian J; Giannakakou, Paraskevi

2014-01-07

Circulating tumor cells (CTCs) have emerged as a reliable source of tumor cells, and their concentration has prognostic implications. CTC capture offers real-time access to cancer tissue without the need of an invasive biopsy, while their phenotypic and molecular interrogation can provide insight into the biological changes of the tumor that occur during treatment. The majority of the CTC capture methods are based on EpCAM expression as a surface marker of tumor-derived cells. However, EpCAM protein expression levels can be significantly down regulated during cancer progression as a consequence of the process of epithelial to mesenchymal transition. In this paper, we describe a novel HER2 (Human Epidermal Receptor 2)-based microfluidic device for the isolation of CTCs from peripheral blood of patients with HER2-expressing solid tumors. We selected HER2 as an alternative to EpCAM as the receptor is biologically and therapeutically relevant in several solid tumors, like breast cancer (BC), where it is overexpressed in 30% of the patients and expressed in 90%, and gastric cancer (GC), in which HER2 presence is identified in more than 60% of the cases. We tested the performance of various anti HER2 antibodies in a panel of nine different BC cell lines with varying HER2 protein expression levels, using immunoblotting, confocal microscopy, live cells imaging and flow cytometry analyses. The antibody associated with the highest capture efficiency and sensitivity for HER2 expressing cells on the microfluidic device was the one that performed best in live cells imaging and flow cytometry assays as opposed to the fixed cell analyses, suggesting that recognition of the native conformation of the HER2 extracellular epitope on living cells was essential for specificity and sensitivity of CTC capture. Next, we tested the performance of the HER2 microfluidic device using blood from metastatic breast and gastric cancer patients. The HER2 microfluidic device exhibited CTC capture in 9/9 blood samples. Thus, the described HER2-based microfluidic device can be considered as a valid clinically relevant method for CTC capture in HER2 expressing solid cancers.

Electrolytes for Li-Ion Cells in Low Temperature Applications

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Surampudi, S.

2000-01-01

Prototype AA-size lithium-ion cells have been demonstrated to operate effectively at temperatures as low as -30 to -40 C. These improvements in low temperature cell performance have been realized by the incorporation of ethylene carbonate-based electrolytes which possess low melting, low viscosity cosolvents, such as methyl acetate, ethyl acetate, gamma-butyrolactone, and ethyl methyl carbonate. The cells containing a 0.75M LiPF6 EC+DEC+DMC+EMC (1:1:1:1) electrolyte displayed the best performance at -30 C (> 90% of the room temperature capacity at approximately C/15 rate), whereas, at -40 C the cells with the 0.75M LiPF6 EC+DEC+DMC+MA (1:1:1:1) and 0.75M LiPF6 EC+DEC+DMC+EA (1:1:1:1) electrolytes showed superior performance.

A mathematical model for the iron/chromium redox battery

NASA Technical Reports Server (NTRS)

Fedkiw, P. S.; Watts, R. W.

1984-01-01

A mathematical model has been developed to describe the isothermal operation of a single anode-separator-cathode unit cell in a redox-flow battery and has been applied to the NASA iron/chromium system. The model, based on porous electrode theory, incorporates redox kinetics, mass transfer, and ohmic effects as well as the parasitic hydrogen reaction which occurs in the chromium electrode. A numerical parameter study was carried out to predict cell performance to aid in the rational design, scale-up, and operation of the flow battery. The calculations demonstrate: (1) an optimum electrode thickness and electrolyte flow rate exist; (2) the amount of hydrogen evolved and, hence, cycle faradaic efficiency, can be affected by cell geometry, flow rate, and charging procedure; (3) countercurrent flow results in enhanced cell performance over cocurrent flow; and (4) elevated temperature operation enhances cell performance.

Efficient Purification and Release of Circulating Tumor Cells by Synergistic Effect of Biomarker and SiO2 @Gel-Microbead-Based Size Difference Amplification.

PubMed

Huang, Qinqin; Cai, Bo; Chen, Bolei; Rao, Lang; He, Zhaobo; He, Rongxiang; Guo, Feng; Zhao, Libo; Kondamareddy, Kiran Kumar; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

2016-07-01

Microfluidics-based circulating tumor cell (CTC) isolation is achieved by using gelatin-coated silica microbeads conjugated to CTC-specific antibodies. Bead-binding selectively enlarges target cell size, providing efficient high-purity capture. CTCs captured can be further released non-invasively. This stratagem enables high-performance CTC isolation for subsequent studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid Column-Free Enrichment of Mononuclear Cells from Solid Tissues

PubMed Central

Scoville, Steven D.; Keller, Karen A.; Cheng, Stephanie; Zhang, Michael; Zhang, Xiaoli; Caligiuri, Michael A.; Freud, Aharon G.

2015-01-01

We have developed a rapid negative selection method to enrich rare mononuclear cells from human tissues. Unwanted and antibody-tethered cells are selectively depleted during a Ficoll separation step, and there is no need for magnetic-based reagents and equipment. The new method is fast, customizable, inexpensive, remarkably efficient, and easy to perform, and per sample the overall cost is less than one-tenth the cost associated with a magnetic column-based method. PMID:26223896

Ternary Polymer Solar Cells based on Two Acceptors and One Donor for Achieving 12.2% Efficiency.

PubMed

Zhao, Wenchao; Li, Sunsun; Zhang, Shaoqing; Liu, Xiaoyu; Hou, Jianhui

2017-01-01

Ternary polymer solar cells are fabricated based on one donor PBDB-T and two acceptors (a methyl-modified small-molecular acceptor (IT-M) and a bis-adduct of Bis[70]PCBM). A high power conversion efficiency of 12.2% can be achieved. The photovoltaic performance of the ternary polymer solar cells is not sensitive to the composition of the blend. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor

PubMed Central

Tian, Haining; Oscarsson, Johan; Gabrielsson, Erik; Eriksson, Susanna K.; Lindblad, Rebecka; Xu, Bo; Hao, Yan; Boschloo, Gerrit; Johansson, Erik M. J.; Gardner, James M.; Hagfeldt, Anders; Rensmo, Håkan; Sun, Licheng

2014-01-01

Supramolecular interactions based on porphyrin and fullerene derivatives were successfully adopted to improve the photovoltaic performance of p-type dye-sensitized solar cells (DSCs). Photoelectron spectroscopy (PES) measurements suggest a change in binding configuration of ZnTCPP after co-sensitization with C60PPy, which could be ascribed to supramolecular interaction between ZnTCPP and C60PPy. The performance of the ZnTCPP/C60PPy-based p-type DSC has been increased by a factor of 4 in comparison with the DSC with the ZnTCPP alone. At 560 nm, the IPCE value of DSCs based on ZnTCPP/C60PPy was a factor of 10 greater than that generated by ZnTCPP-based DSCs. The influence of different electrolytes on charge extraction and electron lifetime was investigated and showed that the enhanced Voc from the Co2+/3+(dtbp)3-based device is due to the positive EF shift of NiO. PMID:24603319

Surface modification of starch based blends using potassium permanganate-nitric acid system and its effect on the adhesion and proliferation of osteoblast-like cells.

PubMed

Pashkuleva, I; Marques, A P; Vaz, F; Reis, R L

2005-01-01

The surface modification of three starch based polymeric biomaterials, using a KMnO4/HNO3 oxidizing system, and the effect of that modification on the osteoblastic cell adhesion has been investigated. The rationale of this work is as follows--starch based polymers have been proposed for use as tissue engineering scaffolds in several publications. It is known that in biodegradable systems it is quite difficult to have both cell adhesion and proliferation. Starch based polymers have shown to perform better than poly-lactic acid based materials but there is still room for improvement. This particular work is aimed at enhancing cell adhesion and proliferation on the surface of several starch based polymer blends that are being proposed as tissue engineering scaffolds. The surface of the polymeric biomaterials was chemically modified using a KMnO4/HNO3 system. This treatment resulted in more hydrophilic surfaces, which was confirmed by contact angle measurements. The effect of the treatment on the bioactivity of the surface modified biomaterials was also studied. The bioactivity tests, performed in simulated body fluid after biomimetic coating, showed that a dense film of calcium phosphate was formed after 30 days. Finally, human osteoblast-like cells were cultured on unmodified (control) and modified materials in order to observe the effect of the presence of higher numbers of polar groups on the adhesion and proliferation of those cells. Two of the modified polymers presented changes in the adhesion behavior and a significant increase in the proliferation rate kinetics when compared to the unmodified controls.

Programmable and multiparameter DNA-based logic platform for cancer recognition and targeted therapy.

PubMed

You, Mingxu; Zhu, Guizhi; Chen, Tao; Donovan, Michael J; Tan, Weihong

2015-01-21

The specific inventory of molecules on diseased cell surfaces (e.g., cancer cells) provides clinicians an opportunity for accurate diagnosis and intervention. With the discovery of panels of cancer markers, carrying out analyses of multiple cell-surface markers is conceivable. As a trial to accomplish this, we have recently designed a DNA-based device that is capable of performing autonomous logic-based analysis of two or three cancer cell-surface markers. Combining the specific target-recognition properties of DNA aptamers with toehold-mediated strand displacement reactions, multicellular marker-based cancer analysis can be realized based on modular AND, OR, and NOT Boolean logic gates. Specifically, we report here a general approach for assembling these modular logic gates to execute programmable and higher-order profiling of multiple coexisting cell-surface markers, including several found on cancer cells, with the capacity to report a diagnostic signal and/or deliver targeted photodynamic therapy. The success of this strategy demonstrates the potential of DNA nanotechnology in facilitating targeted disease diagnosis and effective therapy.

From in vitro to in vivo: Integration of the virtual cell based assay with physiologically based kinetic modelling.

PubMed

Paini, Alicia; Sala Benito, Jose Vicente; Bessems, Jos; Worth, Andrew P

2017-12-01

Physiologically based kinetic (PBK) models and the virtual cell based assay can be linked to form so called physiologically based dynamic (PBD) models. This study illustrates the development and application of a PBK model for prediction of estragole-induced DNA adduct formation and hepatotoxicity in humans. To address the hepatotoxicity, HepaRG cells were used as a surrogate for liver cells, with cell viability being used as the in vitro toxicological endpoint. Information on DNA adduct formation was taken from the literature. Since estragole induced cell damage is not directly caused by the parent compound, but by a reactive metabolite, information on the metabolic pathway was incorporated into the model. In addition, a user-friendly tool was developed by implementing the PBK/D model into a KNIME workflow. This workflow can be used to perform in vitro to in vivo extrapolation and forward as backward dosimetry in support of chemical risk assessment. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Heading-vector navigation based on head-direction cells and path integration.

PubMed

Kubie, John L; Fenton, André A

2009-05-01

Insect navigation is guided by heading vectors that are computed by path integration. Mammalian navigation models, on the other hand, are typically based on map-like place representations provided by hippocampal place cells. Such models compute optimal routes as a continuous series of locations that connect the current location to a goal. We propose a "heading-vector" model in which head-direction cells or their derivatives serve both as key elements in constructing the optimal route and as the straight-line guidance during route execution. The model is based on a memory structure termed the "shortcut matrix," which is constructed during the initial exploration of an environment when a set of shortcut vectors between sequential pairs of visited waypoint locations is stored. A mechanism is proposed for calculating and storing these vectors that relies on a hypothesized cell type termed an "accumulating head-direction cell." Following exploration, shortcut vectors connecting all pairs of waypoint locations are computed by vector arithmetic and stored in the shortcut matrix. On re-entry, when local view or place representations query the shortcut matrix with a current waypoint and goal, a shortcut trajectory is retrieved. Since the trajectory direction is in head-direction compass coordinates, navigation is accomplished by tracking the firing of head-direction cells that are tuned to the heading angle. Section 1 of the manuscript describes the properties of accumulating head-direction cells. It then shows how accumulating head-direction cells can store local vectors and perform vector arithmetic to perform path-integration-based homing. Section 2 describes the construction and use of the shortcut matrix for computing direct paths between any pair of locations that have been registered in the shortcut matrix. In the discussion, we analyze the advantages of heading-based navigation over map-based navigation. Finally, we survey behavioral evidence that nonhippocampal, heading-based navigation is used in small mammals and humans. Copyright 2008 Wiley-Liss, Inc.

Comparison of the uptake of methacrylate-based nanoparticles in static and dynamic in vitro systems as well as in vivo.

PubMed

Rinkenauer, Alexandra C; Press, Adrian T; Raasch, Martin; Pietsch, Christian; Schweizer, Simon; Schwörer, Simon; Rudolph, Karl L; Mosig, Alexander; Bauer, Michael; Traeger, Anja; Schubert, Ulrich S

2015-10-28

Polymer-based nanoparticles are promising drug delivery systems allowing the development of new drug and treatment strategies with reduced side effects. However, it remains a challenge to screen for new and effective nanoparticle-based systems in vitro. Important factors influencing the behavior of nanoparticles in vivo cannot be simulated in screening assays in vitro, which still represent the main tools in academic research and pharmaceutical industry. These systems have serious drawbacks in the development of nanoparticle-based drug delivery systems, since they do not consider the highly complex processes influencing nanoparticle clearance, distribution, and uptake in vivo. In particular, the transfer of in vitro nanoparticle performance to in vivo models often fails, demonstrating the urgent need for novel in vitro tools that can imitate aspects of the in vivo situation more accurate. Dynamic cell culture, where cells are cultured and incubated in the presence of shear stress has the potential to bridge this gap by mimicking key-features of organs and vessels. Our approach implements and compares a chip-based dynamic cell culture model to the common static cell culture and mouse model to assess its capability to predict the in vivo success more accurately, by using a well-defined poly((methyl methacrylate)-co-(methacrylic acid)) and poly((methyl methacrylate)-co-(2-dimethylamino ethylmethacrylate)) based nanoparticle library. After characterization in static and dynamic in vitro cell culture we were able to show that physiological conditions such as cell-cell communication of co-cultured endothelial cells and macrophages as well as mechanotransductive signaling through shear stress significantly alter cellular nanoparticle uptake. In addition, it could be demonstrated by using dynamic cell cultures that the in vivo situation is simulated more accurately and thereby can be applied as a novel system to investigate the performance of nanoparticle systems in vivo more reliable. Copyright © 2015. Published by Elsevier B.V.

Controlling the Morphology of BDTT-DPP-Based Small Molecules via End-Group Functionalization for Highly Efficient Single and Tandem Organic Photovoltaic Cells.

PubMed

Kim, Ji-Hoon; Park, Jong Baek; Yang, Hoichang; Jung, In Hwan; Yoon, Sung Cheol; Kim, Dongwook; Hwang, Do-Hoon

2015-11-04

A series of narrow-band gap, π-conjugated small molecules based on diketopyrrolopyrrole (DPP) electron acceptor units coupled with alkylthienyl-substituted-benzodithiophene (BDTT) electron donors were designed and synthesized for use as donor materials in solution-processed organic photovoltaic cells. In particular, by end-group functionalization of the small molecules with fluorine derivatives, the nanoscale morphologies of the photoactive layers of the photovoltaic cells were successfully controlled. The influences of different fluorine-based end-groups on the optoelectronic and morphological properties, carrier mobilities, and the photovoltaic performances of these materials were investigated. A high power conversion efficiency (PCE) of 6.00% under simulated solar light (AM 1.5G) illumination has been achieved for organic photovoltaic cells based on a small-molecule bulk heterojunction system consisting of a trifluoromethylbenzene (CF3) end-group-containing oligomer (BDTT-(DPP)2-CF3) as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. As a result, the introduction of CF3 end-groups has been found to enhance both the short circuit current density (JSC) and fill factor (FF). A tandem photovoltaic device comprising an inverted BDTT-(DPP)2-CF3:PC71BM cell and a poly(3-hexylthiophene) (P3HT):indene-C60-bisadduct (IC60BA)-based cell as the top and bottom cell components, respectively, showed a maximum PCE of 8.30%. These results provide valuable guidelines for the rational design of conjugated small molecules for applications in high-performance organic photovoltaic cells. Furthermore, to the best of our knowledge, this is the first report on the design of fluorine-functionalized BDTT-DPP-based small molecules, which have been shown to be a viable candidate for use in inverted tandem cells.

Component analysis and target cell-based neuroactivity screening of Panax ginseng by ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry.

PubMed

Yuan, Jinbin; Chen, Yang; Liang, Jian; Wang, Chong-Zhi; Liu, Xiaofei; Yan, Zhihong; Tang, Yi; Li, Jiankang; Yuan, Chun-Su

2016-12-01

Ginseng is one of the most widely used natural medicines in the world. Recent studies have suggested Panax ginseng has a wide range of beneficial effects on aging, central nervous system disorders, and neurodegenerative diseases. However, knowledge about the specific bioactive components of ginseng is still limited. This work aimed to screen for the bioactive components in Panax ginseng that act against neurodegenerative diseases, using the target cell-based bioactivity screening method. Firstly, component analysis of Panax ginseng extracts was performed by UPLC-QTOF-MS, and a total of 54 compounds in white ginseng were characterized and identified according to the retention behaviors, accurate MW, MS characteristics, parent nucleus, aglycones, side chains, and literature data. Then target cell-based bioactivity screening method was developed to predict the candidate compounds in ginseng with SH-SY5Y cells. Four ginsenosides, Rg 2 , Rh 1 , Ro, and Rd, were observed to be active. The target cell-based bioactivity screening method coupled with UPLC-QTOF-MS technique has suitable sensitivity and it can be used as a screening tool for low content bioactive constituents in natural products. Copyright © 2016 Elsevier B.V. All rights reserved.

Small Molecule Acceptor and Polymer Donor Crystallinity and Aggregation Effects on Microstructure Templating: Understanding Photovoltaic Response in Fullerene-Free Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eastham, Nicholas D.; Dudnik, Alexander S.; Aldrich, Thomas J.

Perylenediimide (PDI) small molecule acceptor (SMA) crystallinity and donor polymer aggregation and crystallinity effects on bulk-heterojunction microstructure and polymer solar cell (PSC) performance are systematically investigated. Two highperformance polymers, semicrystalline poly[5-(2-hexyldodecyl)-4Hthieno[3,4-c]pyrrole-4,6(5H)-dione-1,3-yl-alt-4,4''dodecyl-2,2':5',2''- terthiophene-5,5''-diyl] (PTPD3T or D1) and amorphous poly{4,8- bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene- 2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate-2,6-diyl) (PBDTT-FTTE or D2), are paired with three PDI-based SMAs (A1-A3) of differing crystallinity (A1 is the most, A3 is the least crystalline). The resulting PSC performance trends are strikingly different from those of typical fullerene-based PSCs and are highly material-dependent. The present trends reflect synergistic aggregation propensities between the SMA and polymer components. Importantly, the active layer morphology is templatedmore » by the PDI in some blends and by the polymer in others, with the latter largely governed by the polymer aggregation. Thus, PTPD3T templating capacity increases as self-aggregation increases (greater Mn), optimizing PSC performance with A2, while A3-based cells exhibit an inverse relationship between polymer aggregation and performance, which is dramatically different from fullerene-based PSCs. For PBDTT-FTTE, A2-based cells again deliver the highest PCEs of ~5%, but here both A2 and PBDTT-FTTE (medium Mn) template the morphology. Overall, the present results underscore the importance of nonfullerene acceptor aggregation for optimizing PSC performance and offer guidelines for pairing SMAs with acceptable donor polymers.« less

Tunable Microfluidic Devices for Hydrodynamic Fractionation of Cells and Beads: A Review

PubMed Central

Alvankarian, Jafar; Majlis, Burhanuddin Yeop

2015-01-01

The adjustable microfluidic devices that have been developed for hydrodynamic-based fractionation of beads and cells are important for fast performance tunability through interaction of mechanical properties of particles in fluid flow and mechanically flexible microstructures. In this review, the research works reported on fabrication and testing of the tunable elastomeric microfluidic devices for applications such as separation, filtration, isolation, and trapping of single or bulk of microbeads or cells are discussed. Such microfluidic systems for rapid performance alteration are classified in two groups of bulk deformation of microdevices using external mechanical forces, and local deformation of microstructures using flexible membrane by pneumatic pressure. The main advantage of membrane-based tunable systems has been addressed to be the high capability of integration with other microdevice components. The stretchable devices based on bulk deformation of microstructures have in common advantage of simplicity in design and fabrication process. PMID:26610519

Multilayer-Grown Ultrathin Nanostructured GaAs Solar Cells as a Cost-Competitive Materials Platform for III-V Photovoltaics.

PubMed

Gai, Boju; Sun, Yukun; Lim, Haneol; Chen, Huandong; Faucher, Joseph; Lee, Minjoo L; Yoon, Jongseung

2017-01-24

Large-scale deployment of GaAs solar cells in terrestrial photovoltaics demands significant cost reduction for preparing device-quality epitaxial materials. Although multilayer epitaxial growth in conjunction with printing-based materials assemblies has been proposed as a promising route to achieve this goal, their practical implementation remains challenging owing to the degradation of materials properties and resulting nonuniform device performance between solar cells grown in different sequences. Here we report an alternative approach to circumvent these limitations and enable multilayer-grown GaAs solar cells with uniform photovoltaic performance. Ultrathin single-junction GaAs solar cells having a 300-nm-thick absorber (i.e., emitter and base) are epitaxially grown in triple-stack releasable multilayer assemblies by molecular beam epitaxy using beryllium as a p-type impurity. Microscale (∼500 × 500 μm 2 ) GaAs solar cells fabricated from respective device layers exhibit excellent uniformity (<3% relative) of photovoltaic performance and contact properties owing to the suppressed diffusion of p-type dopant as well as substantially reduced time of epitaxial growth associated with ultrathin device configuration. Bifacial photon management employing hexagonally periodic TiO 2 nanoposts and a vertical p-type metal contact serving as a metallic back-surface reflector together with specialized epitaxial design to minimize parasitic optical losses for efficient light trapping synergistically enable significantly enhanced photovoltaic performance of such ultrathin absorbers, where ∼17.2% solar-to-electric power conversion efficiency under simulated AM1.5G illumination is demonstrated from 420-nm-thick single-junction GaAs solar cells grown in triple-stack epitaxial assemblies.

Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells

NASA Technical Reports Server (NTRS)

Jain, Raj K.

2005-01-01

Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

Determination of thermal properties of commercial Ni-MH cells

NASA Astrophysics Data System (ADS)

Darcy, Eric C.

1994-02-01

The test objectives were to evaluate the electrical and thermal performance of commercial Ni-MH cells, evaluate the effectiveness of commercial charge control circuits, assess the abuse tolerance of these cells, and correlate performance and abuse tolerances to cell design via disassembly. Design objectives were to determine which cell designs are most suitable for scale-up and to guide the design of future shuttle and space station based battery chargers. Results, displayed in viewgraph format, include: reflex charging with ICS circuit resulted in premature charge termination; Ni-MH cells appear very tolerant to overcharge at low rates; Enstore's charger is more electrically and thermally efficient at high rates; and Ni-MH cycles much more efficiently than Ni-Cd with the delta-V/delta-t termination.

Determination of thermal properties of commercial Ni-MH cells

NASA Technical Reports Server (NTRS)

Darcy, Eric C.

1994-01-01

The test objectives were to evaluate the electrical and thermal performance of commercial Ni-MH cells, evaluate the effectiveness of commercial charge control circuits, assess the abuse tolerance of these cells, and correlate performance and abuse tolerances to cell design via disassembly. Design objectives were to determine which cell designs are most suitable for scale-up and to guide the design of future shuttle and space station based battery chargers. Results, displayed in viewgraph format, include: reflex charging with ICS circuit resulted in premature charge termination; Ni-MH cells appear very tolerant to overcharge at low rates; Enstore's charger is more electrically and thermally efficient at high rates; and Ni-MH cycles much more efficiently than Ni-Cd with the delta-V/delta-t termination.

Correlation of electron and proton irradiation-induced damage in InP solar cells

NASA Technical Reports Server (NTRS)

Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

1995-01-01

When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

A multilayer microdevice for cell-based high-throughput drug screening

NASA Astrophysics Data System (ADS)

Liu, Chong; Wang, Lei; Xu, Zheng; Li, Jingmin; Ding, Xiping; Wang, Qi; Chunyu, Li

2012-06-01

A multilayer polydimethylsiloxane microdevice for cell-based high-throughput drug screening is described in this paper. This established microdevice was based on a modularization method and it integrated a drug/medium concentration gradient generator (CGG), pneumatic microvalves and a cell culture microchamber array. The CGG was able to generate five steps of linear concentrations with the same outlet flow rate. The medium/drug flowed through CGG and then into the pear-shaped cell culture microchambers vertically. This vertical perfusion mode was used to reduce the impact of the shear stress on the physiology of cells induced by the fluid flow in the microchambers. Pear-shaped microchambers with two arrays of miropillars at each outlet were adopted in this microdevice, which were beneficial to cell distribution. The chemotherapeutics Cisplatin (DDP)-induced Cisplatin-resistant cell line A549/DDP apoptotic experiments were performed well on this platform. The results showed that this novel microdevice could not only provide well-defined and stable conditions for cell culture, but was also useful for cell-based high-throughput drug screening with less reagents and time consumption.

Enhancement of photovoltaic performance of flexible perovskite solar cells by means of ionic liquid interface modification in a low temperature all solution process

NASA Astrophysics Data System (ADS)

Chu, Weijing; Yang, Junyou; Jiang, Qinghui; Li, Xin; Xin, Jiwu

2018-05-01

The quality of interface between the electron transport layer (ETL) and perovskite is very crucial to the photovoltaic performance of a flexible perovskite solar cell fabricated under low-temperature process. This work demonstrates a room temperature ionic liquid modification strategy to the interface between ZnO layer and MAPbI3 film for high performance flexible perovskite solar cells based on a PET substrate. [BMIM]BF4 ionic liquid modification can significantly improve the surface quality and wettability of the ZnO ETL, thus greatly increase the charge mobility of ZnO ETL and improve the crystalline of perovskite film based on it. Moreover, the dipolar polarization layer among the ZnO ETL with perovskite, built by modification, can adjust the energy level between the ZnO ETL and perovskite and facilitates the charge extraction. Therefore, an overall power conversion efficiency (PCE) of 12.1% have been achieved under standard illumination, it increases by 1.4 times of the flexible perovskite solar cells on a pristine ZnO ETL.

Low resistivity ZnO-GO electron transport layer based CH{sub 3}NH{sub 3}PbI{sub 3} solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Muhammad Imran, E-mail: imranrahbar@scme.nust.edu.pk, E-mail: amirhabib@scme.nust.edu.pk; Hussain, Zakir; Mujahid, Mohammad

Perovskite based solar cells have demonstrated impressive performances. Controlled environment synthesis and expensive hole transport material impede their potential commercialization. We report ambient air synthesis of hole transport layer free devices using ZnO-GO as electron selective contacts. Solar cells fabricated with hole transport layer free architecture under ambient air conditions with ZnO as electron selective contact achieved an efficiency of 3.02%. We have demonstrated that by incorporating GO in ZnO matrix, low resistivity electron selective contacts, critical to improve the performance, can be achieved. We could achieve max efficiency of 4.52% with our completed devices for ZnO: GO composite. Impedancemore » spectroscopy confirmed the decrease in series resistance and an increase in recombination resistance with inclusion of GO in ZnO matrix. Effect of temperature on completed devices was investigated by recording impedance spectra at 40 and 60 {sup o}C, providing indirect evidence of the performance of solar cells at elevated temperatures.« less

A novel measure and significance testing in data analysis of cell image segmentation.

PubMed

Wu, Jin Chu; Halter, Michael; Kacker, Raghu N; Elliott, John T; Plant, Anne L

2017-03-14

Cell image segmentation (CIS) is an essential part of quantitative imaging of biological cells. Designing a performance measure and conducting significance testing are critical for evaluating and comparing the CIS algorithms for image-based cell assays in cytometry. Many measures and methods have been proposed and implemented to evaluate segmentation methods. However, computing the standard errors (SE) of the measures and their correlation coefficient is not described, and thus the statistical significance of performance differences between CIS algorithms cannot be assessed. We propose the total error rate (TER), a novel performance measure for segmenting all cells in the supervised evaluation. The TER statistically aggregates all misclassification error rates (MER) by taking cell sizes as weights. The MERs are for segmenting each single cell in the population. The TER is fully supported by the pairwise comparisons of MERs using 106 manually segmented ground-truth cells with different sizes and seven CIS algorithms taken from ImageJ. Further, the SE and 95% confidence interval (CI) of TER are computed based on the SE of MER that is calculated using the bootstrap method. An algorithm for computing the correlation coefficient of TERs between two CIS algorithms is also provided. Hence, the 95% CI error bars can be used to classify CIS algorithms. The SEs of TERs and their correlation coefficient can be employed to conduct the hypothesis testing, while the CIs overlap, to determine the statistical significance of the performance differences between CIS algorithms. A novel measure TER of CIS is proposed. The TER's SEs and correlation coefficient are computed. Thereafter, CIS algorithms can be evaluated and compared statistically by conducting the significance testing.

A probabilistic approach to photovoltaic generator performance prediction

NASA Astrophysics Data System (ADS)

Khallat, M. A.; Rahman, S.

1986-09-01

A method for predicting the performance of a photovoltaic (PV) generator based on long term climatological data and expected cell performance is described. The equations for cell model formulation are provided. Use of the statistical model for characterizing the insolation level is discussed. The insolation data is fitted to appropriate probability distribution functions (Weibull, beta, normal). The probability distribution functions are utilized to evaluate the capacity factors of PV panels or arrays. An example is presented revealing the applicability of the procedure.

Nanopillar based electrochemical biosensor for monitoring microfluidic based cell culture

NASA Astrophysics Data System (ADS)

Gangadharan, Rajan

In-vitro assays using cultured cells have been widely performed for studying many aspects of cell biology and cell physiology. These assays also form the basis of cell based sensing. Presently, analysis procedures on cell cultures are done using techniques that are not integrated with the cell culture system. This approach makes continuous and real-time in-vitro measurements difficult. It is well known that the availability of continuous online measurements for extended periods of time will help provide a better understanding and will give better insight into cell physiological events. With this motivation we developed a highly sensitive, selective and stable microfluidic electrochemical glucose biosensor to make continuous glucose measurements in cell culture media. The performance of the microfluidic biosensor was enhanced by adding 3D nanopillars to the electrode surfaces. The microfluidic glucose biosensor consisted of three electrodes---Enzyme electrode, Working electrode, and Counter electrode. All these electrodes were enhanced with nanopillars and were optimized in their respective own ways to obtain an effective and stable biosensing device in cell culture media. For example, the 'Enzyme electrode' was optimized for enzyme immobilization via either a polypyrrole-based or a self-assembled-monolayer-based immobilization method, and the 'Working electrode' was modified with Prussian Blue or electropolymerized Neutral Red to reduce the working potential and also the interference from other interacting electro-active species. The complete microfluidic biosensor was tested for its ability to monitor glucose concentration changes in cell culture media. The significance of this work is multifold. First, the developed device may find applications in continuous and real-time measurements of glucose concentrations in in-vitro cell cultures. Second, the development of a microfluidic biosensor will bring technical know-how toward constructing continuous glucose monitoring devices. Third, the methods used to develop 3D electrodes incorporated with nanopillars can be used for other applications such as neural probes, fuel cells, solar cells etc., and finally, the knowledge obtained from the immobilization of enzymes onto nanostructures sheds some new insight into nanomaterial/biomolecule interactions.

Optoelectronic and Photovoltaic Performances of Pyridine Based Monomer and Polymer Capped ZnO Dye-Sensitized Solar Cells.

PubMed

Singh, Satbir; Raj, Tilak; Singh, Amarpal; Kaur, Navneet

2016-06-01

The present research work describes the comparative analysis and performance characteristics of 4-pyridine based monomer and polymer capped ZnO dye-sensitized solar cells. The N, N-dimethyl-N4-((pyridine-4yl)methylene) propaneamine (4,monomer) and polyamine-4-pyridyl Schiff base (5, polymer) dyes were synthesized through one step condensation reaction between 4-pyridinecarboxaldehyde 1 and N, N-dimethylpropylamine 2/polyamine 3. Products obtained N, N-dimethyl-N4-((pyridine-4yl)methylene)propaneamine (4) and polyamine-4-pyridyl Schiff base (5) were purified and characterized using 1H, 13C NMR, mass, IR and CHN spectroscopy. Both the dyes 4 and 5 were further coated over ZnO nanoparticles and characterized using SEM, DLS and XRD analysis. Absorption profile and emission profile was monitored using fluorescence and UV-Vis absorption spectroscopy. A thick layer of these inbuilt dye linked ZnO nanoparticles of dyes (4) and (5) was pasted on one of the conductive side of ITO glass followed with a liquid electrolyte and counter electrode of the same conductive glass. Polyamine-4-pyridyl Schiff base polymer (5) decorated dye sensitized solar cell has shown better exciting photovoltaic properties in the form of short circuit current density (J(sc) = 6.3 mA/cm2), open circuit photo voltage (V(oc) = 0.7 V), fill factor (FF = 0.736) than monomer decorated dye sensitized solar cell. Polymer dye (5) based ZnO solar cell has shown a maximum solar power to electrical conversion efficiency of 3.25%, which is enhanced by 2.16% in case of monomer dye based ZnO solar cell under AM 1.5 sun illuminations.

Performance Characteristics of Lithium Ion Polymeric Electrolyte Cells

NASA Technical Reports Server (NTRS)

Shen, D.; Nagasubramanian, G.; Huang, C-K.; Surampudi, S.; Halpert, G.

1994-01-01

A series of polyacrylonitrile-based (PAN) electrolytes containing LiAsF6 and a number of solvent mixtures including ethylene carbonate (EC) + propylene carbonate (PC) were prepared, electrochemically evaluated and used as electrolyte in the polymer cells.

Band gap grading and photovoltaic performance of solution-processed Cu(In,Ga)S2 thin-film solar cells.

PubMed

Sohn, So Hyeong; Han, Noh Soo; Park, Yong Jin; Park, Seung Min; An, Hee Sang; Kim, Dong-Wook; Min, Byoung Koun; Song, Jae Kyu

2014-12-28

The photophysical properties of CuInxGa1-xS2 (CIGS) thin films, prepared by solution-based coating methods, are investigated to understand the correlation between the optical properties of these films and the electrical characteristics of solar cells fabricated using these films. Photophysical properties, such as the depth-dependent band gap and carrier lifetime, turn out to be at play in determining the energy conversion efficiency of solar cells. A double grading of the band gap in CIGS films enhances solar cell efficiency, even when defect states disturb carrier collection by non-radiative decay. The combinational stacking of different density films leads to improved solar cell performance as well as efficient fabrication because a graded band gap and reduced shunt current increase carrier collection efficiency. The photodynamics of minority-carriers suggests that the suppression of defect states is a primary area of improvement in CIGS thin films prepared by solution-based methods.

Vapor and healing treatment for CH3NH3PbI3-xClx films toward large-area perovskite solar cells

NASA Astrophysics Data System (ADS)

Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A.; Bouhadana, Yaniv; Zaban, Arie

2016-03-01

Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm2). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (Voc, Jsc, Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ~100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a ``healing effect'' to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method.Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm2). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (Voc, Jsc, Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ~100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a ``healing effect'' to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08658b

Optimization of primary printed batteries based on Zn/MnO2

NASA Astrophysics Data System (ADS)

Madej, E.; Espig, M.; Baumann, R. R.; Schuhmann, W.; La Mantia, F.

2014-09-01

Thin-film batteries based on zinc/manganese dioxide chemistry with gel ZnCl2 electrolyte were manufactured as single (1.5 V) and double (3.0 V) cells from electrodes printed on paper substrates covered with different polymeric insulating coatings. Their properties were evaluated by means of electrochemical impedance spectroscopy and chronopotentiometry. Best performing cells achieved capacities in the range of 3 mAh cm-2 during discharge with 100 μA current, corresponding approximately to C/100 discharge rate. The influence of the cell elements on the overvoltage was examined and suggestions for the optimization of their performance were postulated. In particular, it was observed that limitations in the delivered power were governed by the poor conductivity of the carbon current collector. An optimized cell was built and showed a 4-fold improvement in the power delivered at 1 mA.

Morphology evolution in high-performance polymer solar cells processed from nonhalogenated solvent

DOE PAGES

Cai, Wanzhu; Liu, Peng; Jin, Yaocheng; ...

2015-05-26

A new processing protocol based on non-halogenated solvent and additive is developed to produce polymer solar cells with power conversion efficiencies better than those processed from commonly used halogenated solvent-additive pair. Morphology studies show that good performance correlates with a finely distributed nanomorphology with a well-defined polymer fibril network structure, which leads to balanced charge transport in device operation.

Computational cell quantification in the human brain tissues based on hard x-ray phase-contrast tomograms

NASA Astrophysics Data System (ADS)

Hieber, Simone E.; Bikis, Christos; Khimchenko, Anna; Schulz, Georg; Deyhle, Hans; Thalmann, Peter; Chicherova, Natalia; Rack, Alexander; Zdora, Marie-Christine; Zanette, Irene; Schweighauser, Gabriel; Hench, Jürgen; Müller, Bert

2016-10-01

Cell visualization and counting plays a crucial role in biological and medical research including the study of neurodegenerative diseases. The neuronal cell loss is typically determined to measure the extent of the disease. Its characterization is challenging because the cell density and size already differs by more than three orders of magnitude in a healthy cerebellum. Cell visualization is commonly performed by histology and fluorescence microscopy. These techniques are limited to resolve complex microstructures in the third dimension. Phase- contrast tomography has been proven to provide sufficient contrast in the three-dimensional imaging of soft tissue down to the cell level and, therefore, offers the basis for the three-dimensional segmentation. Within this context, a human cerebellum sample was embedded in paraffin and measured in local phase-contrast mode at the beamline ID19 (ESRF, Grenoble, France) and the Diamond Manchester Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK). After the application of Frangi-based filtering the data showed sufficient contrast to automatically identify the Purkinje cells and to quantify their density to 177 cells per mm3 within the volume of interest. Moreover, brain layers were segmented in a region of interest based on edge detection. Subsequently performed histological analysis validated the presence of the cells, which required a mapping from the two- dimensional histological slices to the three-dimensional tomogram. The methodology can also be applied to further tissue types and shows potential for the computational tissue analysis in health and disease.

Unique cell culture systems for ground based research

NASA Technical Reports Server (NTRS)

Lewis, Marian L.

1990-01-01

The horizontally rotating fluid-filled, membrane oxygenated bioreactors developed at NASA Johnson for spacecraft applications provide a powerful tool for ground-based research. Three-dimensional aggregates formed by cells cultured on microcarrier beads are useful for study of cell-cell interactions and tissue development. By comparing electron micrographs of plant seedlings germinated during Shuttle flight 61-C and in an earth-based rotating bioreactor it is shown that some effects of microgravity are mimicked. Bioreactors used in the UAH Bioreactor Laboratory will make it possible to determine some of the effects of altered gravity at the cellular level. Bioreactors can be valuable for performing critical, preliminary-to-spaceflight experiments as well as medical investigations such as in vitro tumor cell growth and chemotherapeutic drug response; the enrichment of stem cells from bone marrow; and the effect of altered gravity on bone and muscle cell growth and function and immune response depression.

Automated Deep Learning-Based System to Identify Endothelial Cells Derived from Induced Pluripotent Stem Cells.

PubMed

Kusumoto, Dai; Lachmann, Mark; Kunihiro, Takeshi; Yuasa, Shinsuke; Kishino, Yoshikazu; Kimura, Mai; Katsuki, Toshiomi; Itoh, Shogo; Seki, Tomohisa; Fukuda, Keiichi

2018-06-05

Deep learning technology is rapidly advancing and is now used to solve complex problems. Here, we used deep learning in convolutional neural networks to establish an automated method to identify endothelial cells derived from induced pluripotent stem cells (iPSCs), without the need for immunostaining or lineage tracing. Networks were trained to predict whether phase-contrast images contain endothelial cells based on morphology only. Predictions were validated by comparison to immunofluorescence staining for CD31, a marker of endothelial cells. Method parameters were then automatically and iteratively optimized to increase prediction accuracy. We found that prediction accuracy was correlated with network depth and pixel size of images to be analyzed. Finally, K-fold cross-validation confirmed that optimized convolutional neural networks can identify endothelial cells with high performance, based only on morphology. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same

DOEpatents

Angell, C Austen [Mesa, AZ; Xu, Wu [Broadview Heights, OH; Belieres, Jean-Philippe [Chandler, AZ; Yoshizawa, Masahiro [Tokyo, JP

2011-01-11

Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the high performance of the non-corrosive proton-transfer ionic liquids as high temperature fuel cell electrolytes. Performance of simple H.sub.2(g) electrolyte/O.sub.2(g) fuel cells with the new electrolytes is described. Superior performance both at ambient temperature and temperatures up to and above 200.degree. C. are achieved. Both neutral proton transfer salts and the acid salts with HSO.sup.-.sub.4 anions, give good results, the bisulphate case being particularly good at low temperatures and very high temperatures. The performance of all electrolytes is improved by the addition of a small amount of involatile base of pK.sub.a value intermediate between those of the acid and base that make the bulk electrolyte. The preferred case is the imidazole-doped ethylammonium hydrogensulfate which yields behavior superior in all respects to that of the industry standard phosphoric acid electrolyte.

ICSH guidelines for the verification and performance of automated cell counters for body fluids.

PubMed

Bourner, G; De la Salle, B; George, T; Tabe, Y; Baum, H; Culp, N; Keng, T B

2014-12-01

One of the many challenges facing laboratories is the verification of their automated Complete Blood Count cell counters for the enumeration of body fluids. These analyzers offer improved accuracy, precision, and efficiency in performing the enumeration of cells compared with manual methods. A patterns of practice survey was distributed to laboratories that participate in proficiency testing in Ontario, Canada, the United States, the United Kingdom, and Japan to determine the number of laboratories that are testing body fluids on automated analyzers and the performance specifications that were performed. Based on the results of this questionnaire, an International Working Group for the Verification and Performance of Automated Cell Counters for Body Fluids was formed by the International Council for Standardization in Hematology (ICSH) to prepare a set of guidelines to help laboratories plan and execute the verification of their automated cell counters to provide accurate and reliable results for automated body fluid counts. These guidelines were discussed at the ICSH General Assemblies and reviewed by an international panel of experts to achieve further consensus. © 2014 John Wiley & Sons Ltd.

Low-temperature fuel cell systems for commercial airplane auxiliary power.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curgus, Dita Brigitte; Pratt, Joseph William; Akhil, Abbas Ali

2010-11-01

This presentation briefly describes the ongoing study of fuel cell systems on-board a commercial airplane. Sandia's current project is focused on Proton Exchange Membrane (PEM) fuel cells applied to specific on-board electrical power needs. They are trying to understand how having a fuel cell on an airplane would affect overall performance. The fuel required to accomplish a mission is used to quantify the performance. Our analysis shows the differences between the base airplane and the airplane with the fuel cell. There are many ways of designing a system, depending on what you do with the waste heat. A system thatmore » requires ram air cooling has a large mass penalty due to increased drag. The bottom-line impact can be expressed as additional fuel required to complete the mission. Early results suggest PEM fuel cells can be used on airplanes with manageable performance impact if heat is rejected properly. For PEMs on aircraft, we are continuing to perform: (1) thermodynamic analysis (investigate configurations); (2) integrated electrical design (with dynamic modeling of the micro grid); (3) hardware assessment (performance, weight, and volume); and (4) galley and peaker application.« less

Gasoline-fueled solid oxide fuel cell using MoO2-Based Anode

NASA Astrophysics Data System (ADS)

Hou, Xiaoxue; Marin-Flores, Oscar; Kwon, Byeong Wan; Kim, Jinsoo; Norton, M. Grant; Ha, Su

2014-12-01

This short communication describes the performance of a solid oxide fuel cell (SOFC) fueled by directly feeding premium gasoline to the anode without using external reforming. The novel component of the fuel cell that enables such operation is the mixed conductivity of MoO2-based anode. Using this anode, a fuel cell demonstrating a maximum power density of 31 mW/cm2 at 0.45 V was successfully fabricated. Over a 24 h period of operation, the open cell voltage remained stable at ∼0.92 V. Scanning electron microscopy (SEM) examination of the anode surface pre- and post-testing showed no evidence of coking.

Piezoresistance and solar cell efficiency

NASA Technical Reports Server (NTRS)

Weizer, Victor G.

1987-01-01

Diffusion-induced stresses in silicon are shown to result in large localized changes in the minority-carrier mobility which in turn can have a significant effect on cell output. Evidence is given that both compressive and tensile stresses can be generated in either the emitter or the base region. Tensile stresses in the base appear to be much more effective in altering cell performance than do compressive stresses. While most stress-related effects appear to degrade cell efficiency, this is not always the case. Evidence is presented showing that arsenic-induced stresses can result in emitter characteristics comparable to those found in the MINP cell without requiring a high degree of surface passivation.

Photothermal quantitative phase imaging of living cells with nanoparticles utilizing a cost-efficient setup

NASA Astrophysics Data System (ADS)

Turko, Nir A.; Isbach, Michael; Ketelhut, Steffi; Greve, Burkhard; Schnekenburger, Jürgen; Shaked, Natan T.; Kemper, Björn

2017-02-01

We explored photothermal quantitative phase imaging (PTQPI) of living cells with functionalized nanoparticles (NPs) utilizing a cost-efficient setup based on a cell culture microscope. The excitation light was modulated by a mechanical chopper wheel with low frequencies. Quantitative phase imaging (QPI) was performed with Michelson interferometer-based off-axis digital holographic microscopy and a standard industrial camera. We present results from PTQPI observations on breast cancer cells that were incubated with functionalized gold NPs binding to the epidermal growth factor receptor. Moreover, QPI was used to quantify the impact of the NPs and the low frequency light excitation on cell morphology and viability.

Efficient CsF interlayer for high and low bandgap polymer solar cell

NASA Astrophysics Data System (ADS)

Mitul, Abu Farzan; Sarker, Jith; Adhikari, Nirmal; Mohammad, Lal; Wang, Qi; Khatiwada, Devendra; Qiao, Qiquan

2018-02-01

Low bandgap polymer solar cells have a great deal of importance in flexible photovoltaic market to absorb sun light more efficiently. Efficient wide bandgap solar cells are always available in nature to absorb visible photons. The development and incorporation of infrared photovoltaics (IR PV) with wide bandgap solar cells can improve overall solar device performance. Here, we have developed an efficient low bandgap polymer solar cell with CsF as interfacial layer in regular structure. Polymer solar cell devices with CsF shows enhanced performance than Ca as interfacial layer. The power conversion efficiency of 4.5% has been obtained for PDPP3T based polymer solar cell with CsF as interlayer. Finally, an optimal thickness with CsF as interfacial layer has been found to improve the efficiency in low bandgap polymer solar cells.

Seventh workshop on the role of impurities and defects in silicon device processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1997-08-01

This workshop is the latest in a series which has looked at technological issues related to the commercial development and success of silicon based photovoltaic (PV) modules. PV modules based on silicon are the most common at present, but face pressure from other technologies in terms of cell performance and cell cost. This workshop addresses a problem which is a factor in the production costs of silicon based PV modules.

Dry-Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells.

PubMed

Zhang, Xiaoliang; Aitola, Kerttu; Hägglund, Carl; Kaskela, Antti; Johansson, Malin B; Sveinbjörnsson, Kári; Kauppinen, Esko I; Johansson, Erik M J

2017-01-20

Single-walled carbon nanotubes (SWCNTs) show great potential as an alternative material for front electrodes in photovoltaic applications, especially for flexible devices. In this work, a press-transferred transparent SWCNT film was utilized as front electrode for colloidal quantum dot solar cells (CQDSCs). The solar cells were fabricated on both glass and flexible substrates, and maximum power conversion efficiencies of 5.5 and 5.6 %, respectively, were achieved, which corresponds to 90 and 92 % of an indium-doped tin oxide (ITO)-based device (6.1 %). The SWCNTs are therefore a very good alternative to the ITO-based electrodes especially for flexible solar cells. The optical electric field distribution and optical losses within the devices were simulated theoretically and the results agree with the experimental results. With the optical simulations that were performed it may also be possible to enhance the photovoltaic performance of SWCNT-based solar cells even further by optimizing the device configuration or by using additional optical active layers, thus reducing light reflection of the device and increasing light absorption in the quantum dot layer. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorinated benzothiadiazole-based conjugated polymers for high-performance polymer solar cells without any processing additives or post-treatments.

PubMed

Wang, Ning; Chen, Zheng; Wei, Wei; Jiang, Zhenhua

2013-11-13

Thanks to their many favorable advantages, polymer solar cells exhibit great potential for next-generation clean energy sources. Herein, we have successfully designed and synthesized a series of new fluorinated benzothiadiazole-based conjugated copolymers PBDT(TEH)-DT(H)BTff (P1), PBDT(TEH)-DT(EH)BTff (P2), and PBDT(HDO)-DT(H)BTff (P3). The power conversion efficiencies of 4.46, 6.20, and 8.30% were achieved for P1-, P2-, and P3-based devices within ~100 nm thickness active layers under AM 1.5G illumination without any processing additives or post-treatments, respectively. The PCE of 8.30% for P3 is the highest value for the reported traditional single-junction polymer solar cells via a simple fabrication architecture without any additives or post-treatments. In addition, it is noteworthy that P3 also allows making high efficient polymer solar cells with high PCEs of 7.27 and 6.56% under the same condition for ~200 and ~300 nm thickness active layers, respectively. Excellent photoelectric properties and good solubility make polymer P3 become an alternative material for high-performance polymer solar cells.

Polyoxometalate-modified TiO2 nanotube arrays photoanode materials for enhanced dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Liu, Ran; Sun, Zhixia; Zhang, Yuzhuo; Xu, Lin; Li, Na

2017-10-01

In this work, we prepared for the first time the TiO2 nanotube arrays (TNAs) photoanode with polyoxometalate(POMs)-modified TiO2 electron-transport layer for improving the performance of zinc phthalocyanine(ZnPc)-sensitized solar cells. The as-prepared POMs/TNAs/ZnPc composite photoanode exhibited higher photovoltaic performances than the TNAs/ZnPc photoanode, so that the power conversion efficiency of the solar cell device based on the POMs/TNAs/ZnPc photoanode displayed a notable improvement of 45%. These results indicated that the POMs play a key role in reducing charge recombination in phthalocyanine-sensitized solar cells, together with TiO2 nanotube arrays being helpful for electron transport. The mechanism of the performance improvement was demonstrated by the measurements of electrochemical impedance spectra and open-circuit voltage decay curves. Although the resulting performance is still below that of the state-of-the-art dye-sensitized solar cells, this study presents a new insight into improving the power conversion efficiency of phthalocyanine-sensitized solar cells via polyoxometalate-modified TiO2 nanotube arrays photoanode.

Progress in Tandem Solar Cells Based on Hybrid Organic-Inorganic Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Bo; Zheng, Xiaopeng; Bai, Yang

Owing to their high efficiency, low-cost solution-processability, and tunable bandgap, perovskite solar cells (PSCs) made of hybrid organic-inorganic perovskite (HOIP) thin films are promising top-cell candidates for integration with bottom-cells based on Si or other low-bandgap solar-cell materials to boost the power conversion efficiency (PCE) beyond the Shockley-Quiesser (S-Q) limit. In this review, recent progress in such tandem solar cells based on the emerging PSCs is summarized and reviewed critically. Notable achievements for different tandem solar cell configurations including mechanically-stacked, optical coupling, and monolithically-integrated with PSCs as top-cells are described in detail. Highly-efficient semitransparent PSC top-cells with high transmittance inmore » near-infrared (NIR) region are critical for tandem solar cells. Different types of transparent electrodes with high transmittance and low sheet-resistance for PSCs are reviewed, which presents a grand challenge for PSCs. The strategies to obtain wide-bandgap PSCs with good photo-stability are discussed. In conclusion, the PCE reduction due to reflection loss, parasitic absorption, electrical loss, and current mismatch are analyzed to provide better understanding of the performance of PSC-based tandem solar cells.« less

Progress in Tandem Solar Cells Based on Hybrid Organic-Inorganic Perovskites

DOE PAGES

Chen, Bo; Zheng, Xiaopeng; Bai, Yang; ...

2017-03-06

Owing to their high efficiency, low-cost solution-processability, and tunable bandgap, perovskite solar cells (PSCs) made of hybrid organic-inorganic perovskite (HOIP) thin films are promising top-cell candidates for integration with bottom-cells based on Si or other low-bandgap solar-cell materials to boost the power conversion efficiency (PCE) beyond the Shockley-Quiesser (S-Q) limit. In this review, recent progress in such tandem solar cells based on the emerging PSCs is summarized and reviewed critically. Notable achievements for different tandem solar cell configurations including mechanically-stacked, optical coupling, and monolithically-integrated with PSCs as top-cells are described in detail. Highly-efficient semitransparent PSC top-cells with high transmittance inmore » near-infrared (NIR) region are critical for tandem solar cells. Different types of transparent electrodes with high transmittance and low sheet-resistance for PSCs are reviewed, which presents a grand challenge for PSCs. The strategies to obtain wide-bandgap PSCs with good photo-stability are discussed. In conclusion, the PCE reduction due to reflection loss, parasitic absorption, electrical loss, and current mismatch are analyzed to provide better understanding of the performance of PSC-based tandem solar cells.« less

Base Station Placement Algorithm for Large-Scale LTE Heterogeneous Networks.

PubMed

Lee, Seungseob; Lee, SuKyoung; Kim, Kyungsoo; Kim, Yoon Hyuk

2015-01-01

Data traffic demands in cellular networks today are increasing at an exponential rate, giving rise to the development of heterogeneous networks (HetNets), in which small cells complement traditional macro cells by extending coverage to indoor areas. However, the deployment of small cells as parts of HetNets creates a key challenge for operators' careful network planning. In particular, massive and unplanned deployment of base stations can cause high interference, resulting in highly degrading network performance. Although different mathematical modeling and optimization methods have been used to approach various problems related to this issue, most traditional network planning models are ill-equipped to deal with HetNet-specific characteristics due to their focus on classical cellular network designs. Furthermore, increased wireless data demands have driven mobile operators to roll out large-scale networks of small long term evolution (LTE) cells. Therefore, in this paper, we aim to derive an optimum network planning algorithm for large-scale LTE HetNets. Recently, attempts have been made to apply evolutionary algorithms (EAs) to the field of radio network planning, since they are characterized as global optimization methods. Yet, EA performance often deteriorates rapidly with the growth of search space dimensionality. To overcome this limitation when designing optimum network deployments for large-scale LTE HetNets, we attempt to decompose the problem and tackle its subcomponents individually. Particularly noting that some HetNet cells have strong correlations due to inter-cell interference, we propose a correlation grouping approach in which cells are grouped together according to their mutual interference. Both the simulation and analytical results indicate that the proposed solution outperforms the random-grouping based EA as well as an EA that detects interacting variables by monitoring the changes in the objective function algorithm in terms of system throughput performance.

Hole and electron extraction layers based on graphene oxide derivatives for high-performance bulk heterojunction solar cells.

PubMed

Liu, Jun; Xue, Yuhua; Gao, Yunxiang; Yu, Dingshan; Durstock, Michael; Dai, Liming

2012-05-02

By charge neutralization of carboxylic acid groups in graphene oxide (GO) with Cs(2)CO(3) to afford Cesium-neutralized GO (GO-Cs), GO derivatives with appropriate modification are used as both hole- and electron-extraction layers for bulk heterojunction (BHJ) solar cells. The normal and inverted devices based on GO hole- and GO-Cs electron-extraction layers both outperform the corresponding standard BHJ solar cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Efficiency Large Area Polysilicon Solar Cells

NASA Technical Reports Server (NTRS)

Johnson, S. M.; Winter, C.

1985-01-01

Large area (100 sq cm) polysilicon solar cells having efficiencies of up to 14.1% (100 mW/sq cm, 25 C) were fabricated and a detailed analysis was performed to identify the efficiency loss mechanisms. The 1-5 characteristics of the best cell were dominated by recombination in the quasi-neutral base due to the combination of minority carrier diffusion length and base resistivity. An analysis of the microstructural defects present in the material and their effect on the electrical properties is presented.

Effect of Grain Boundaries on the Performance of Thin-Film-Based Polycrystalline Silicon Solar Cells: A Numerical Modeling

NASA Astrophysics Data System (ADS)

Chhetri, Nikita; Chatterjee, Somenath

2018-01-01

Solar cells/photovoltaic, a renewable energy source, is appraised to be the most effective alternative to the conventional electrical energy generator. A cost-effective alternative of crystalline wafer-based solar cell is thin-film polycrystalline-based solar cell. This paper reports the numerical analysis of dependency of the solar cell parameters (i.e., efficiency, fill factor, open-circuit voltage and short-circuit current density) on grain size for thin-film-based polycrystalline silicon (Si) solar cells. A minority carrier lifetime model is proposed to do a correlation between the grains, grain boundaries and lifetime for thin-film-based polycrystalline Si solar cells in MATLAB environment. As observed, the increment in the grain size diameter results in increase in minority carrier lifetime in polycrystalline Si thin film. A non-equivalent series resistance double-diode model is used to find the dark as well as light (AM1.5) current-voltage (I-V) characteristics for thin-film-based polycrystalline Si solar cells. To optimize the effectiveness of the proposed model, a successive approximation method is used and the corresponding fitting parameters are obtained. The model is validated with the experimentally obtained results reported elsewhere. The experimentally reported solar cell parameters can be found using the proposed model described here.

Aerosol feed direct methanol fuel cell

NASA Technical Reports Server (NTRS)

Kindler, Andrew (Inventor); Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

2002-01-01

Improvements to fuel cells include introduction of the fuel as an aerosol of liquid fuel droplets suspended in a gas. The particle size of the liquid fuel droplets may be controlled for optimal fuel cell performance by selection of different aerosol generators or by separating droplets based upon size using a particle size conditioner.

Improved Academic Performance and Student Perceptions of Learning through Use of a Cell Phone-Based Personal Response System

ERIC Educational Resources Information Center

Ma, Sihui; Steger, Daniel G.; Doolittle, Peter E.; Stewart, Amanda C.

2018-01-01

Personal response systems, such as clickers, have been widely used to improve the effectiveness of teaching in various classroom settings. Although hand-held clicker response systems have been the subject of multiple prior studies, few studies have focused on the use of cell phone-based personal response system (CPPRS) specifically. This study…

Chitosan and alginate types of bio-membrane in fuel cell application: An overview

NASA Astrophysics Data System (ADS)

Shaari, N.; Kamarudin, S. K.

2015-09-01

The major problems of polymer electrolyte membrane fuel cell technology that need to be highlighted are fuel crossovers (e.g., methanol or hydrogen leaking across fuel cell membranes), CO poisoning, low durability, and high cost. Chitosan and alginate-based biopolymer membranes have recently been used to solve these problems with promising results. Current research in biopolymer membrane materials and systems has focused on the following: 1) the development of novel and efficient biopolymer materials; and 2) increasing the processing capacity of membrane operations. Consequently, chitosan and alginate-based biopolymers seek to enhance fuel cell performance by improving proton conductivity, membrane durability, and reducing fuel crossover and electro-osmotic drag. There are four groups of chitosan-based membranes (categorized according to their reaction and preparation): self-cross-linked and salt-complexed chitosans, chitosan-based polymer blends, chitosan/inorganic filler composites, and chitosan/polymer composites. There are only three alginate-based membranes that have been synthesized for fuel cell application. This work aims to review the state-of-the-art in the growth of chitosan and alginate-based biopolymer membranes for fuel cell applications.

Increased bacterial cell density and recombinant protein yield using a commercial microbial cultivation system.

PubMed

Peck, Grantley R; Bowden, Timothy R; Shiell, Brian J; Michalski, Wojtek P

2014-01-01

EnBase (BioSilta, Finland) is a microbial cultivation system that replicates fed-batch systems through sustained release of glucose by enzymatic degradation of a polymeric substrate. Achievable bacterial cell densities and recombinant capripoxvirus protein expression levels, solubility, and antigenicity using the EnBase system were assessed. BL21-AI Escherichia coli expressing capripoxvirus proteins achieved up to eightfold higher cell densities when grown in EnBase media compared with standard media. Greater yields of capripoxvirus proteins were attained using EnBase media, either through increases in the amount of expressed protein per cell in conjunction with higher cell density or through the increase in cell density alone. Addition of EnBase booster enhanced protein yield for one of the proteins tested but reduced yield for the other. However, the amount of soluble forms of the capripoxvirus proteins tested was not different from that observed from cultures grown under standard conditions. Purified capripoxvirus proteins expressed using EnBase or standard media were assessed for their performance by enzyme-linked immunosorbent assay (ELISA) and were shown to be equally capable of specifically binding capripoxvirus antibodies.

Progress in nanostructured photoanodes for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Liu, Xueyang; Fang, Jian; Liu, Yong; Lin, Tong

2016-09-01

Solar cells represent a principal energy technology to convert light into electricity. Commercial solar cells are at present predominately produced by single- or multi-crystalline silicon wafers. The main drawback to silicon-based solar cells, however, is high material and manufacturing costs. Dye-sensitized solar cells (DSSCs) have attracted much attention during recent years because of the low production cost and other advantages. The photoanode (working electrode) plays a key role in determining the performance of DSSCs. In particular, nanostructured photoanodes with a large surface area, high electron transfer efficiency, and low electron recombination facilitate to prepare DSSCs with high energy conversion efficiency. In this review article, we summarize recent progress in the development of novel photoanodes for DSSCs. Effect of semiconductor material (e.g. TiO2, ZnO, SnO2, N2O5, and nano carbon), preparation, morphology and structure (e.g. nanoparticles, nanorods, nanofibers, nanotubes, fiber/particle composites, and hierarchical structure) on photovoltaic performance of DSSCs is described. The possibility of replacing silicon-based solar cells with DSSCs is discussed.

Introducing Mammalian Cell Culture and Cell Viability Techniques in the Undergraduate Biology Laboratory.

PubMed

Bowey-Dellinger, Kristen; Dixon, Luke; Ackerman, Kristin; Vigueira, Cynthia; Suh, Yewseok K; Lyda, Todd; Sapp, Kelli; Grider, Michael; Crater, Dinene; Russell, Travis; Elias, Michael; Coffield, V McNeil; Segarra, Verónica A

2017-01-01

Undergraduate students learn about mammalian cell culture applications in introductory biology courses. However, laboratory modules are rarely designed to provide hands-on experience with mammalian cells or teach cell culture techniques, such as trypsinization and cell counting. Students are more likely to learn about cell culture using bacteria or yeast, as they are typically easier to grow, culture, and manipulate given the equipment, tools, and environment of most undergraduate biology laboratories. In contrast, the utilization of mammalian cells requires a dedicated biological safety cabinet and rigorous antiseptic techniques. For this reason, we have devised a laboratory module and method herein that familiarizes students with common cell culture procedures, without the use of a sterile hood or large cell culture facility. Students design and perform a time-efficient inquiry-based cell viability experiment using HeLa cells and tools that are readily available in an undergraduate biology laboratory. Students will become familiar with common techniques such as trypsinizing cells, cell counting with a hemocytometer, performing serial dilutions, and determining cell viability using trypan blue dye. Additionally, students will work with graphing software to analyze their data and think critically about the mechanism of death on a cellular level. Two different adaptations of this inquiry-based lab are presented-one for non-biology majors and one for biology majors. Overall, these laboratories aim to expose students to mammalian cell culture and basic techniques and help them to conceptualize their application in scientific research.

Introducing Mammalian Cell Culture and Cell Viability Techniques in the Undergraduate Biology Laboratory †

PubMed Central

Bowey-Dellinger, Kristen; Dixon, Luke; Ackerman, Kristin; Vigueira, Cynthia; Suh, Yewseok K.; Lyda, Todd; Sapp, Kelli; Grider, Michael; Crater, Dinene; Russell, Travis; Elias, Michael; Coffield, V. McNeil; Segarra, Verónica A.

2017-01-01

Undergraduate students learn about mammalian cell culture applications in introductory biology courses. However, laboratory modules are rarely designed to provide hands-on experience with mammalian cells or teach cell culture techniques, such as trypsinization and cell counting. Students are more likely to learn about cell culture using bacteria or yeast, as they are typically easier to grow, culture, and manipulate given the equipment, tools, and environment of most undergraduate biology laboratories. In contrast, the utilization of mammalian cells requires a dedicated biological safety cabinet and rigorous antiseptic techniques. For this reason, we have devised a laboratory module and method herein that familiarizes students with common cell culture procedures, without the use of a sterile hood or large cell culture facility. Students design and perform a time-efficient inquiry-based cell viability experiment using HeLa cells and tools that are readily available in an undergraduate biology laboratory. Students will become familiar with common techniques such as trypsinizing cells, cell counting with a hemocytometer, performing serial dilutions, and determining cell viability using trypan blue dye. Additionally, students will work with graphing software to analyze their data and think critically about the mechanism of death on a cellular level. Two different adaptations of this inquiry-based lab are presented—one for non-biology majors and one for biology majors. Overall, these laboratories aim to expose students to mammalian cell culture and basic techniques and help them to conceptualize their application in scientific research. PMID:28861134

3D+time acquisitions of 3D cell culture by means of lens-free tomographic microscopy

NASA Astrophysics Data System (ADS)

Berdeu, Anthony; Laperrousaz, Bastien; Bordy, Thomas; Morales, S.; Gidrol, Xavier; Picollet-D'hahan, Nathalie; Allier, Cédric

2018-02-01

We propose a three-dimensional (3D) imaging platform based on lens-free microscopy to perform multi-angle acquisitions on 3D cell cultures embedded in extracellular matrix (ECM). We developed algorithms based on the Fourier diffraction theorem to perform fully 3D reconstructions of biological samples and we adapted the lens-free microscope to incubator conditions. Here we demonstrate for the first time, 3D+time lens-free acquisitions of 3D cell culture over 8 days directly into the incubator. The 3D reconstructed volume is as large as 5 mm3 and provides a unique way to observe in the same 3D cell culture experiment multiple cell migration strategies. Namely, in a 3D cell culture of prostate epithelial cells embedded within a Matrigel® matrix, we are able to distinguish single cell 'leaders', migration of cell clusters, migration of large aggregates of cells, and also close-gap and large-scale branching. In addition, we observe long-scale 3D deformations of the ECM that modify the geometry of the 3D cell culture. Interestingly, we also observed the opposite, i.e. we found that large aggregates of cells may deform the ECM by generating traction forces over very long distances. In sum we put forward a novel 3D lens-free microscopy tomographic technique to study the single and collective cell migrations, the cell-to-cell interactions and the cell-to-matrix interactions.

Modeling and experimental performance of an intermediate temperature reversible solid oxide cell for high-efficiency, distributed-scale electrical energy storage

NASA Astrophysics Data System (ADS)

Wendel, Christopher H.; Gao, Zhan; Barnett, Scott A.; Braun, Robert J.

2015-06-01

Electrical energy storage is expected to be a critical component of the future world energy system, performing load-leveling operations to enable increased penetration of renewable and distributed generation. Reversible solid oxide cells, operating sequentially between power-producing fuel cell mode and fuel-producing electrolysis mode, have the capability to provide highly efficient, scalable electricity storage. However, challenges ranging from cell performance and durability to system integration must be addressed before widespread adoption. One central challenge of the system design is establishing effective thermal management in the two distinct operating modes. This work leverages an operating strategy to use carbonaceous reactant species and operate at intermediate stack temperature (650 °C) to promote exothermic fuel-synthesis reactions that thermally self-sustain the electrolysis process. We present performance of a doped lanthanum-gallate (LSGM) electrolyte solid oxide cell that shows high efficiency in both operating modes at 650 °C. A physically based electrochemical model is calibrated to represent the cell performance and used to simulate roundtrip operation for conditions unique to these reversible systems. Design decisions related to system operation are evaluated using the cell model including current density, fuel and oxidant reactant compositions, and flow configuration. The analysis reveals tradeoffs between electrical efficiency, thermal management, energy density, and durability.

Multichannel Interdiffusion Driven FASnI3 Film Formation Using Aqueous Hybrid Salt/Polymer Solutions toward Flexible Lead-Free Perovskite Solar Cells.

PubMed

Xi, Jun; Wu, Zhaoxin; Jiao, Bo; Dong, Hua; Ran, Chenxin; Piao, Chengcheng; Lei, Ting; Song, Tze-Bin; Ke, Weijun; Yokoyama, Takamichi; Hou, Xun; Kanatzidis, Mercouri G

2017-06-01

Tin (Sn)-based perovskites are increasingly attractive because they offer lead-free alternatives in perovskite solar cells. However, depositing high-quality Sn-based perovskite films is still a challenge, particularly for low-temperature planar heterojunction (PHJ) devices. Here, a "multichannel interdiffusion" protocol is demonstrated by annealing stacked layers of aqueous solution deposited formamidinium iodide (FAI)/polymer layer followed with an evaporated SnI 2 layer to create uniform FASnI 3 films. In this protocol, tiny FAI crystals, significantly inhibited by the introduced polymer, can offer multiple interdiffusion pathways for complete reaction with SnI 2 . What is more, water, rather than traditional aprotic organic solvents, is used to dissolve the precursors. The best-performing FASnI 3 PHJ solar cell assembled by this protocol exhibits a power conversion efficiency (PCE) of 3.98%. In addition, a flexible FASnI 3 -based flexible solar cell assembled on a polyethylene naphthalate-indium tin oxide flexible substrate with a PCE of 3.12% is demonstrated. This novel interdiffusion process can help to further boost the performance of lead-free Sn-based perovskites. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heat transfer enhancement in a lithium-ion cell through improved material-level thermal transport

NASA Astrophysics Data System (ADS)

Vishwakarma, Vivek; Waghela, Chirag; Wei, Zi; Prasher, Ravi; Nagpure, Shrikant C.; Li, Jianlin; Liu, Fuqiang; Daniel, Claus; Jain, Ankur

2015-12-01

While Li-ion cells offer excellent electrochemical performance for several applications including electric vehicles, they also exhibit poor thermal transport characteristics, resulting in reduced performance, overheating and thermal runaway. Inadequate heat removal from Li-ion cells originates from poor thermal conductivity within the cell. This paper identifies the rate-limiting material-level process that dominates overall thermal conduction in a Li-ion cell. Results indicate that thermal characteristics of a Li-ion cell are largely dominated by heat transfer across the cathode-separator interface rather than heat transfer through the materials themselves. This interfacial thermal resistance contributes around 88% of total thermal resistance in the cell. Measured value of interfacial resistance is close to that obtained from theoretical models that account for weak adhesion and large acoustic mismatch between cathode and separator. Further, to address this problem, an amine-based chemical bridging of the interface is carried out. This is shown to result in in four-times lower interfacial thermal resistance without deterioration in electrochemical performance, thereby increasing effective thermal conductivity by three-fold. This improvement is expected to reduce peak temperature rise during operation by 60%. By identifying and addressing the material-level root cause of poor thermal transport in Li-ion cells, this work may contributes towards improved thermal performance of Li-ion cells.

High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide.

PubMed

Zhu, Huimin; Pan, Mingao; Johansson, Malin B; Johansson, Erik M J

2017-06-22

Here, a lead-free silver bismuth iodide (AgI/BiI 3 ) with a crystal structure with space group R3‾ m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from solution on top of TiO 2 and the conducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole-transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth-halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi 2 I 7 , and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X-ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾ m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal-halides efficient in solar cells and points out new directions for further exploration of lead-free metal-halide solar cells. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Optical design of ZnO-based antireflective layers for enhanced GaAs solar cell performance.

PubMed

Lee, Hye Jin; Lee, Jae Won; Kim, Hee Jun; Jung, Dae-Han; Lee, Ki-Suk; Kim, Sang Hyeon; Geum, Dae-myeong; Kim, Chang Zoo; Choi, Won Jun; Baik, Jeong Min

2016-01-28

A series of hierarchical ZnO-based antireflection coatings with different nanostructures (nanowires and nanosheets) is prepared hydrothermally, followed by means of RF sputtering of MgF2 layers for coaxial nanostructures. Structural analysis showed that both ZnO had a highly preferred orientation along the 〈0001〉 direction with a highly crystalline MgF2 shell coated uniformly. However, a small amount of Al was present in nanosheets, originating from Al diffusion from the Al seed layer, resulting in an increase of the optical bandgap. Compared with the nanosheet-based antireflection coatings, the nanowire-based ones exhibited a significantly lower reflectance (∼2%) in ultraviolet and visible light wavelength regions. In particular, they showed perfect light absorption at wavelength less than approximately 400 nm. However, a GaAs single junction solar cell with nanosheet-based antireflection coatings showed the largest enhancement (43.9%) in power conversion efficiency. These results show that the increase of the optical bandgap of the nanosheets by the incorporation of Al atoms allows more photons enter the active region of the solar cell, improving the performance.

Critical advancements in achieving high power and stable nonprecious metal catalyst–based MEAs for real-world proton exchange membrane fuel cell applications

PubMed Central

Zhou, Yingjie; Bai, Kyoung

2018-01-01

Despite great progress in the development of nonprecious metal catalysts (NPMCs) over the past several decades, the performance and stability of these promising catalysts have not yet achieved commercial readiness for proton exchange membrane fuel cells (PEMFCs). Through rational design of the cathode catalyst layer (CCL), we demonstrate the highest reported performance for an NPMC-based membrane electrode assembly (MEA), achieving a peak power of 570 mW/cm2 under air. This record performance is achieved using a precommercial catalyst for which nearly all pores are <3 nm in diameter, challenging previous beliefs regarding the need for larger catalyst pores to achieve high current densities. This advance is achieved at industrially relevant scales (50 cm2 MEA) using a precommercial NPMC. In situ electrochemical analysis of the CCLs is also used to help gain insight into the degradation mechanism observed during galvanostatic testing. Overall, the performance of this NPMC-based MEA has achieved commercial readiness and will be introduced into an NPMC-based product for portable power applications. PMID:29582018

The Solar Spectrum on the Martian Surface and its Effect on Photovoltaic Performance

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Hyatt, Daniel

2007-01-01

Solar cells operating on the surface of Mars receive a spectrum of illumination different from the AM0 spectrum, since the sunlight is filtered by dust suspended in the atmosphere. This spectrum changes with the amount of dust in the atmosphere, as well as with air mass change due to time of day and season. This spectral variation affects the performance of solar cells. We used data from Mars Exploration Rovers to measure this spectrum. By comparing the measured intensity with the known reflectance of the pancam calibration target on the rovers Spirit and Opportunity, we measure the solar spectrum reaching the surface. The effect of this spectrum on the performance of solar cells is then calculated based on the spectral response of several different solar cell types.

The Solar Spectrum on the Martian Surface and Its Effect on Photovoltaic Performance

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Hyatt, Dan

2006-01-01

Solar cells operating on the surface of Mars receive a spectrum of illumination different from the AM0 spectrum, since the sunlight is filtered by dust suspended in the atmosphere. This spectrum changes with the amount of dust in the atmosphere, as well as with air mass change due to time of day and season. This spectral variation affects the performance of solar cells. We used data from Mars Exploration Rovers to measure this spectrum. By comparing the measured intensity with the known reflectance of the pancam calibration target on the rovers Spirit and Opportunity, we measure the solar spectrum reaching the surface. The effect of this spectrum on the performance of solar cells is then calculated based on the spectral response of several different solar cell types.

Loss mechanisms in high-efficiency solar cells: Study of material properties and high-efficiency solar-cell performance on material composition: Project tasks

NASA Technical Reports Server (NTRS)

Sah, C. T.

1985-01-01

Loss mechanisms in high-efficiency solar cells were discussed. Fundamental limitations and practical solutions were stressed. Present cell efficiency is limited by many recombination sites: emitter, base, contacts, and oxide/silicon interface. Use of polysilicon passivation was suggested. After reduction of these losses, a 25% efficient cell could be built. A floating emitter cell design was shown that had the potential of low recombination losses.

Stem cells: a model for screening, discovery and development of drugs.

PubMed

Kitambi, Satish Srinivas; Chandrasekar, Gayathri

2011-01-01

The identification of normal and cancerous stem cells and the recent advances made in isolation and culture of stem cells have rapidly gained attention in the field of drug discovery and regenerative medicine. The prospect of performing screens aimed at proliferation, directed differentiation, and toxicity and efficacy studies using stem cells offers a reliable platform for the drug discovery process. Advances made in the generation of induced pluripotent stem cells from normal or diseased tissue serves as a platform to perform drug screens aimed at developing cell-based therapies against conditions like Parkinson's disease and diabetes. This review discusses the application of stem cells and cancer stem cells in drug screening and their role in complementing, reducing, and replacing animal testing. In addition to this, target identification and major advances in the field of personalized medicine using induced pluripotent cells are also discussed.

Thermo-electrochemical instrumentation of cylindrical Li-ion cells

NASA Astrophysics Data System (ADS)

McTurk, Euan; Amietszajew, Tazdin; Fleming, Joe; Bhagat, Rohit

2018-03-01

The performance evaluation and optimisation of commercially available lithium-ion cells is typically based upon their full cell potential and surface temperature measurements, despite these parameters not being fully representative of the electrochemical processes taking place in the core of the cell or at each electrode. Several methods were devised to obtain the cell core temperature and electrode-specific potential profiles of cylindrical Li-ion cells. Optical fibres with Bragg Gratings were found to produce reliable core temperature data, while their small mechanical profile allowed for low-impact instrumentation method. A pure metallic lithium reference electrode insertion method was identified, avoiding interference with other elements of the cell while ensuring good contact, enabling in-situ observations of the per-electrode electrochemical responses. Our thermo-electrochemical instrumentation technique has enabled us to collect unprecedented cell data, and has subsequently been used in advanced studies exploring the real-world performance limits of commercial cells.

Three year performance of the NTS-2 solar cell experiment

NASA Technical Reports Server (NTRS)

Statler, R. L.; Walker, D. H.

1980-01-01

Twelve different solar cell modules from the NTS 2 experiment are functioning after more than three years in a severe trapped radiation orbit of 20,367 km (10,990 nm) circular, 63 deg inclination. The rate of maximum power degradation may be fit to a predicted rate which is based on twice the value of 1 MeV electron equivalent damage fluence calculated from the space electron model AEI 7. The photovoltaic parameters of the cells are compared to their original values to demonstrate rank order of performance.

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery

PubMed Central

Zhang, Jianjun; Yue, Liping; Kong, Qingshan; Liu, Zhihong; Zhou, Xinhong; Zhang, Chuanjian; Xu, Quan; Zhang, Bo; Ding, Guoliang; Qin, Bingsheng; Duan, Yulong; Wang, Qingfu; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery. PMID:24488228

A carbon-supported copper complex of 3,5-diamino-1,2,4-triazole as a cathode catalyst for alkaline fuel cell applications.

PubMed

Brushett, Fikile R; Thorum, Matthew S; Lioutas, Nicholas S; Naughton, Matthew S; Tornow, Claire; Jhong, Huei-Ru Molly; Gewirth, Andrew A; Kenis, Paul J A

2010-09-08

The performance of a novel carbon-supported copper complex of 3,5-diamino-1,2,4-triazole (Cu-tri/C) is investigated as a cathode material using an alkaline microfluidic H(2)/O(2) fuel cell. The absolute Cu-tri/C cathode performance is comparable to that of a Pt/C cathode. Furthermore, at a commercially relevant potential, the measured mass activity of an unoptimized Cu-tri/C-based cathode was significantly greater than that of similar Pt/C- and Ag/C-based cathodes. Accelerated cathode durability studies suggested multiple degradation regimes at various time scales. Further enhancements in performance and durability may be realized by optimizing catalyst and electrode preparation procedures.

Fuel cell energy service Enron`s commerical program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobson, M.W.

1996-04-01

Enron, the premier provider of clean fuels worldwide, has launched a unique energy service based on fuel cell technology. The goal of this program is to bring the benefits of fuel cell power to the broad commercial marketplace. Enron`s Energy Service is currently based on a 200 kilowatt phosphoric acid power plant manufactured by ONSI Corporation. This plant is fueled by natural gas or propane, and exhibits superior performance. Enron offers a `no hassle` package that provides customers with immediate benefits with no upfront capital or technical risks. This paper describes Enron`s fuel cell commercial program.

Cell module and fuel conditioner development

NASA Technical Reports Server (NTRS)

Feret, J. M.

1981-01-01

A phosphoric acid fuel cell (PAFC) stack design having a 10 kW power rating for operation at higher than atmospheric pressure based on the existing Mark II design configuration is described. Functional analysis, trade studies and thermodynamic cycle analysis for requirements definition and system operating parameter selection purposes were performed. Fuel cell materials and components, and performance testing and evaluation of the repeating electrode components were characterized. The state of the art manufacturing technology for all fuel cell components and the fabrication of short stacks of various sites were established. A 10 kW PAFC stack design for higher pressure operation utilizing the top down systems engineering aproach was developed.

Enhancement of the Power-Conversion Efficiency of Organic Solar Cells via Unveiling an Appropriate Rational Design Strategy in Indacenodithiophene- alt-quinoxaline π-Conjugated Polymers.

PubMed

Chochos, Christos L; Singh, Ranbir; Gregoriou, Vasilis G; Kim, Min; Katsouras, Athanasios; Serpetzoglou, Efthymis; Konidakis, Ioannis; Stratakis, Emmanuel; Cho, Kilwon; Avgeropoulos, Apostolos

2018-03-28

We report on the photovoltaic parameters, photophysical properties, optoelectronic properties, self-assembly, and morphology variations in a series of high-performance donor-acceptor (D-A) π-conjugated polymers based on indacenodithiophene and quinoxaline moieties as a function of the number-average molecular weight ([Formula: see text]), the nature of aryl substituents, and the enlargement of the polymer backbone. One of the most important outcome is that from the three optimization approaches followed to tune the chemical structure toward enhanced photovoltaic performance in bulk heterojunction solar cell devices with the fullerene derivative [6,6]-phenyl-C 71 -butyric acid methyl ester as the electron acceptor, the choice of the aryl substituent is the most efficient rational design strategy. Incorporation of thienyl rings as substituents versus phenyl rings accelerates the electron-hole extraction process to the respective electrode, despite the slightly lower recombination lifetime and, thus, improves the electrical performance of the device. Single-junction solar cells based on ThIDT-TQxT feature a maximum power-conversion efficiency of 7.26%. This study provides significant insights toward understanding of the structure-properties-performance relationship for D-A π-conjugated polymers in solid state, which provide helpful inputs for the design of next-generation polymeric semiconductors for organic solar cells with enhanced performance.

A magnetic micropore chip for rapid (<1 hour) unbiased circulating tumor cell isolation and in situ RNA analysis.

PubMed

Ko, Jina; Bhagwat, Neha; Yee, Stephanie S; Black, Taylor; Redlinger, Colleen; Romeo, Janae; O'Hara, Mark; Raj, Arjun; Carpenter, Erica L; Stanger, Ben Z; Issadore, David

2017-09-12

The use of microtechnology for the highly selective isolation and sensitive detection of circulating tumor cells has shown enormous promise. One challenge for this technology is that the small feature sizes - which are the key to this technology's performance - can result in low sample throughput and susceptibility to clogging. Additionally, conventional molecular analysis of CTCs often requires cells to be taken off-chip for sample preparation and purification before analysis, leading to the loss of rare cells. To address these challenges, we have developed a microchip platform that combines fast, magnetic micropore based negative immunomagnetic selection (>10 mL h -1 ) with rapid on-chip in situ RNA profiling (>100× faster than conventional RNA labeling). This integrated chip can isolate both rare circulating cells and cell clusters directly from whole blood and allow individual cells to be profiled for multiple RNA cancer biomarkers, achieving sample-to-answer in less than 1 hour for 10 mL of whole blood. To demonstrate the power of this approach, we applied our device to the circulating tumor cell based diagnosis of pancreatic cancer. We used a genetically engineered lineage-labeled mouse model of pancreatic cancer (KPCY) to validate the performance of our chip. We show that in a cohort of patient samples (N = 25) that this device can detect and perform in situ RNA analysis on circulating tumor cells in patients with pancreatic cancer, even in those with extremely sparse CTCs (<1 CTC mL -1 of whole blood).

Extracellular electron transfer in yeast-based biofuel cells: A review.

PubMed

Hubenova, Yolina; Mitov, Mario

2015-12-01

This paper reviews the state-of-the art of the yeast-based biofuel cell research and development. The established extracellular electron transfer (EET) mechanisms in the presence and absence of exogenous mediators are summarized and discussed. The approaches applied for improvement of mediator-less yeast-based biofuel cells performance are also presented. The overview of the literature shows that biofuel cells utilizing yeasts as biocatalysts generate power density in the range of 20 to 2440 mW/m(2), which values are comparable with the power achieved when bacteria are used instead. The electrons' origin and the contribution of the glycolysis, fermentation, aerobic respiration, and phosphorylation to the EET are commented. The reported enhanced current generation in aerobic conditions presumes reconsideration of some basic MFC principles. The challenges towards the practical application of the yeast-based biofuel cells are outlined. Copyright © 2015 Elsevier B.V. All rights reserved.

Rambutan-like CNT-Al2O3 scaffolds for high-performance cathode catalyst layers of polymer electrolyte fuel cells

NASA Astrophysics Data System (ADS)

Chang, KwangHyun; Cho, Seonghun; Lim, Eun Ja; Park, Seok-Hee; Yim, Sung-Dae

2018-03-01

Rambutan-like CNT-Al2O3 scaffolds are introduced as a potential candidate for CNT-based catalyst supports to overcome the CNT issues, such as the easy bundling in catalyst ink and the poor pore structure of the CNT-based catalyst layers, and to achieve high MEA performance in PEFCs. Non-porous α-phase Al2O3 balls are introduced to enable the growth of multiwalled CNTs, and Pt nanoparticles are loaded onto the CNT surfaces. In a half-cell, the Pt/CNT-Al2O3 catalyst shows much higher durability than those of a commercial Pt/C catalyst even though it shows lower oxygen reduction reaction (ORR) activity than Pt/C. After using the decal process for MEA formation, the Pt/CNT-Al2O3 shows comparable initial performance characteristics to Pt/C, overcoming the lower ORR activity, mainly due to the facile oxygen transport in the cathode catalyst layers fabricated with the CNT-Al2O3 scaffolds. The Pt/CNT-Al2O3 also exhibits much higher durability against carbon corrosion than Pt/C owing to the durable characteristics of CNTs. Systematic analysis of single cell performance for both initial and after degradation is provided to understand the origin of the high initial performance and durable behavior of Pt/CNT-Al2O3-based catalyst layers. This will provide insights into the design of electrocatalysts for high-performance MEAs in PEFCs.

A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

PubMed Central

Liu, Fei; Li, Fang; Nordin, Anis Nurashikin; Voiculescu, Ioana

2013-01-01

A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35∼45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection. PMID:23459387

Acid-doped polymer nanofiber framework: Three-dimensional proton conductive network for high-performance fuel cells

NASA Astrophysics Data System (ADS)

Tanaka, Manabu; Takeda, Yasushi; Wakiya, Takeru; Wakamoto, Yuta; Harigaya, Kaori; Ito, Tatsunori; Tarao, Takashi; Kawakami, Hiroyoshi

2017-02-01

High-performance polymer electrolyte membranes (PEMs) with excellent proton conductivity, gas barrier property, and membrane stability are desired for future fuel cells. Here we report the development of PEMs based on our proposed new concept "Nanofiber Framework (NfF)." The NfF composite membranes composed of phytic acid-doped polybenzimidazole nanofibers (PBINf) and Nafion matrix show higher proton conductivity than the recast-Nafion membrane without nanofibers. A series of analyses reveal the formation of three-dimensional network nanostructures to conduct protons and water effectively through acid-condensed layers at the interface of PBINf and Nafion matrix. In addition, the NfF composite membrane achieves high gas barrier property and distinguished membrane stability. The fuel cell performance by the NfF composite membrane, which enables ultra-thin membranes with their thickness less than 5 μm, is superior to that by the recast-Nafion membrane, especially at low relative humidity. Such NfF-based high-performance PEM will be accomplished not only by the Nafion matrix used in this study but also by other polymer electrolyte matrices for future PEFCs.

Performance of miniaturized direct methanol fuel cell (DMFC) devices using micropump for fuel delivery

NASA Astrophysics Data System (ADS)

Zhang, Tao; Wang, Qing-Ming

A fuel cell is a device that can convert chemical energy into electricity directly. Among various types of fuel cells, both polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) can work at low temperature (<80 °C). Therefore, they can be used to supply power for commercial portable electronics such as laptop computers, digital cameras, PDAs and cell phones. The focus of this paper is to investigate the performance of a miniaturized DMFC device using a micropump to deliver fuel. The core of this micropump is a piezoelectric ring-type bending actuator and the associated nozzle/diffuser for directing fuel flow. Based on the experimental measurements, it is found that the performance of the fuel cell can be significantly improved if enough fuel flow is induced by the micropump at anode. Three factors may contribute to the performance enhancement including replenishment of methanol, decrease of diffusion resistance and removal of carbon dioxide. In comparison with conventional mini pumps, the size of the piezoelectric micropump is much smaller and the energy consumption is much lower. Thus, it is very viable and effective to use a piezoelectric valveless micropump for fuel delivery in miniaturized DMFC power systems.

Confocal Raman imaging for cancer cell classification

NASA Astrophysics Data System (ADS)

Mathieu, Evelien; Van Dorpe, Pol; Stakenborg, Tim; Liu, Chengxun; Lagae, Liesbet

2014-05-01

We propose confocal Raman imaging as a label-free single cell characterization method that can be used as an alternative for conventional cell identification techniques that typically require labels, long incubation times and complex sample preparation. In this study it is investigated whether cancer and blood cells can be distinguished based on their Raman spectra. 2D Raman scans are recorded of 114 single cells, i.e. 60 breast (MCF-7), 5 cervix (HeLa) and 39 prostate (LNCaP) cancer cells and 10 monocytes (from healthy donors). For each cell an average spectrum is calculated and principal component analysis is performed on all average cell spectra. The main features of these principal components indicate that the information for cell identification based on Raman spectra mainly comes from the fatty acid composition in the cell. Based on the second and third principal component, blood cells could be distinguished from cancer cells; and prostate cancer cells could be distinguished from breast and cervix cancer cells. However, it was not possible to distinguish breast and cervix cancer cells. The results obtained in this study, demonstrate the potential of confocal Raman imaging for cell type classification and identification purposes.

Monolithic-Structured Single-Layered Textile-Based Dye-Sensitized Solar Cells.

PubMed

Yun, Min Ju; Cha, Seung I; Kim, Han Seong; Seo, Seon Hee; Lee, Dong Y

2016-10-06

Textile-structured solar cells are frequently discussed in the literature due to their prospective applications in wearable devices and in building integrated solar cells that utilize their flexibility, mechanical robustness, and aesthetic appearance, but the current approaches for textile-based solar cells-including the preparation of fibre-type solar cells woven into textiles-face several difficulties from high friction and tension during the weaving process. This study proposes a new structural concept and fabrication process for monolithic-structured textile-based dye-sensitized solar cells that are fabricated by a process similar to the cloth-making process, including the preparation of wires and yarns that are woven for use in textiles, printed, dyed, and packaged. The fabricated single-layered textile-based dye-sensitized solar cells successfully act as solar cells in our study, even under bending conditions. By controlling the inter-weft spacing and the number of Ti wires for the photoelectrode conductor, we have found that the performance of this type of dye-sensitized solar cell was notably affected by the spacing between photoelectrodes and counter-electrodes, the exposed areas of Ti wires to photoelectrodes, and photoelectrodes' surface morphology. We believe that this study provides a process and concept for improved textile-based solar cells that can form the basis for further research.

Optimized Carbonate and Ester-Based Li-Ion Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall; Bugga, Ratnakumar

2008-01-01

To maintain high conductivity in low temperatures, electrolyte co-solvents have been designed to have a high dielectric constant, low viscosity, adequate coordination behavior, and appropriate liquid ranges and salt solubilities. Electrolytes that contain ester-based co-solvents in large proportion (greater than 50 percent) and ethylene carbonate (EC) in small proportion (less than 20 percent) improve low-temperature performance in MCMB carbon-LiNiCoO2 lithium-ion cells. These co-solvents have been demonstrated to enhance performance, especially at temperatures down to 70 C. Low-viscosity, ester-based co-solvents were incorporated into multi-component electrolytes of the following composition: 1.0 M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (1:1:8 volume percent) [where X = methyl butyrate (MB), ethyl butyrate EB, methyl propionate (MP), or ethyl valerate (EV)]. These electrolyte formulations result in improved low-temperature performance of lithium-ion cells, with dramatic results at temperatures below 40 C.

Thin-film filament-based solar cells and modules

NASA Astrophysics Data System (ADS)

Tuttle, J. R.; Cole, E. D.; Berens, T. A.; Alleman, J.; Keane, J.

1997-04-01

This concept paper describes a patented, novel photovoltaic (PV) technology that is capable of achieving near-term commercialization and profitability based upon design features that maximize product performance while minimizing initial and future manufacturing costs. DayStar Technologies plans to exploit these features and introduce a product to the market based upon these differential positions. The technology combines the demonstrated performance and reliability of existing thin-film PV product with a cell and module geometry that cuts material usage by a factor of 5, and enhances performance and manufacturability relative to standard flat-plate designs. The target product introduction price is 1.50/Watt-peak (Wp). This is approximately one-half the cost of the presently available PV product. Additional features include: increased efficiency through low-level concentration, no scribe or grid loss, simple series interconnect, high voltage, light weight, high-throughput manufacturing, large area immediate demonstration, flexibility, modularity.

Modeling and performance analysis of movement-based group location management using RFID sensing in public transportation systems.

PubMed

Chung, Yun Won

2012-11-22

Location management, which consists of location registration and paging, is essential to provide mobile communication services to mobile stations (MSs). Since MSs riding on a public transportation system (TS) generates significant location registration signaling loads simultaneously when a TS with riding MSs moves between location areas (LAs), group location management was proposed. Under the group location management, an MS performs group registration when it gets on a TS and performs group deregistration when it gets off a TS. Then, only a TS updates its current location when it changes LA, on behalf of all riding MSs. In this paper, movement-based group location management using radio frequency identification (RFID) is proposed, where the MS's getting on and getting off behaviors are detected using RFID and only location update of a TS is carried out if the number of crossed cells from the last updated cell exceeds a predefined movement threshold, on behalf of all riding MSs. Then, we develop an analytical model for the performance analysis of the movement-based group location management and analyze the effects of various parameters on the performance. The results show that the movement-based group location management has reduced signaling cost compared with movement-based individual location management, and optimal performance can be achieved by choosing appropriate movement threshold values.

Modeling and Performance Analysis of Movement-Based Group Location Management Using RFID Sensing in Public Transportation Systems

PubMed Central

Chung, Yun Won

2012-01-01

Location management, which consists of location registration and paging, is essential to provide mobile communication services to mobile stations (MSs). Since MSs riding on a public transportation system (TS) generates significant location registration signaling loads simultaneously when a TS with riding MSs moves between location areas (LAs), group location management was proposed. Under the group location management, an MS performs group registration when it gets on a TS and performs group deregistration when it gets off a TS. Then, only a TS updates its current location when it changes LA, on behalf of all riding MSs. In this paper, movement-based group location management using radio frequency identification (RFID) is proposed, where the MS’s getting on and getting off behaviors are detected using RFID and only location update of a TS is carried out if the number of crossed cells from the last updated cell exceeds a predefined movement threshold, on behalf of all riding MSs. Then, we develop an analytical model for the performance analysis of the movement-based group location management and analyze the effects of various parameters on the performance. The results show that the movement-based group location management has reduced signaling cost compared with movement-based individual location management, and optimal performance can be achieved by choosing appropriate movement threshold values. PMID:23443368

High power, gel polymer lithium-ion cells with improved low temperature performance for NASA and DoD applications

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.; Chin, K. B.; Surampudi, S.; Narayanan, S. R.; Alamgir, Mohamed; Yu, Ji-Sang; Plichta, Edward P.

2004-01-01

Both NASA and the U.S. Army have interest in developing secondary energy storage devices that are capable of meeting the demanding performance requirements of aerospace and man-portable applications. In order to meet these demanding requirements, gel-polymer electrolyte-based lithium-ion cells are being actively considered, due to their promise of providing high specific energy and enhanced safety aspects.

Investigation of sulfonated polysulfone membranes as electrolyte in a passive-mode direct methanol fuel cell mini-stack

NASA Astrophysics Data System (ADS)

Lufrano, F.; Baglio, V.; Staiti, P.; Stassi, A.; Aricò, A. S.; Antonucci, V.

This paper reports on the development of polymer electrolyte membranes (PEMs) based on sulfonated polysulfone for application in a DMFC mini-stack operating at room temperature in passive mode. The sulfonated polysulfone (SPSf) with two degrees of sulfonation (57 and 66%) was synthesized by a well-known sulfonation process. SPSf membranes with different thicknesses were prepared and investigated. These membranes were characterized in terms of methanol/water uptake, proton conductivity, and fuel cell performance in a DMFC single cell and mini-stack operating at room temperature. The study addressed (a) control of the synthesis of sulfonated polysulfone, (b) optimization of the assembling procedure, (c) a short lifetime investigation and (d) a comparison of DMFC performance in active-mode operation vs. passive-mode operation. The best passive DMFC performance was 220 mW (average cell power density of about 19 mW cm -2), obtained with a thin SPSf membrane (70 μm) at room temperature, whereas the performance of the same membrane-based DMFC in active mode was 38 mW cm -2. The conductivity of this membrane, SPSf (IEC = 1.34 mequiv. g -1) was 2.8 × 10 -2 S cm -1. A preliminary short-term test (200 min) showed good stability during chrono-amperometry measurements.

A rear-end collision risk assessment model based on drivers' collision avoidance process under influences of cell phone use and gender-A driving simulator based study.

PubMed

Li, Xiaomeng; Yan, Xuedong; Wu, Jiawei; Radwan, Essam; Zhang, Yuting

2016-12-01

Driver's collision avoidance performance has a direct link to the collision risk and crash severity. Previous studies demonstrated that the distracted driving, such as using a cell phone while driving, disrupted the driver's performance on road. This study aimed to investigate the manner and extent to which cell phone use and driver's gender affected driving performance and collision risk in a rear-end collision avoidance process. Forty-two licensed drivers completed the driving simulation experiment in three phone use conditions: no phone use, hands-free, and hand-held, in which the drivers drove in a car-following situation with potential rear-end collision risks caused by the leading vehicle's sudden deceleration. Based on the experiment data, a rear-end collision risk assessment model was developed to assess the influence of cell phone use and driver's gender. The cell phone use and driver's gender were found to be significant factors that affected the braking performances in the rear-end collision avoidance process, including the brake reaction time, the deceleration adjusting time and the maximum deceleration rate. The minimum headway distance between the leading vehicle and the simulator during the rear-end collision avoidance process was the final output variable, which could be used to measure the rear-end collision risk and judge whether a collision occurred. The results showed that although cell phone use drivers took some compensatory behaviors in the collision avoidance process to reduce the mental workload, the collision risk in cell phone use conditions was still higher than that without the phone use. More importantly, the results proved that the hands-free condition did not eliminate the safety problem associated with distracted driving because it impaired the driving performance in the same way as much as the use of hand-held phones. In addition, the gender effect indicated that although female drivers had longer reaction time than male drivers in critical situation, they were more quickly in braking with larger maximum deceleration rate, and they tended to keep a larger safety margin with the leading vehicle compared to male drivers. The findings shed some light on the further development of advanced collision avoidance technologies and the targeted intervention strategies about cell phone use while driving. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of Lithium-based Battery Electrolytes Developed under the NASA PERS Program

NASA Technical Reports Server (NTRS)

Bennett, William R.; Baldwin, Richard S.

2006-01-01

Recently, NASA formally completed the Polymer Energy Rechargeable System (PERS) Program, which was established in 2000 in collaboration with the Air Force Research Laboratory (AFRL) to support the development of polymer-based, lithium-based cell chemistries and battery technologies to address the next generation of aerospace applications and mission needs. The goal of this program was to ultimately develop an advanced, space-qualified battery technology, which embodied a solid polymer electrolyte (SPE) and complementary components, with improved performance characteristics that would address future aerospace battery requirements. Programmatically, the PERS initiative exploited both interagency collaborations to address common technology and engineering issues and the active participation of academia and private industry. The initial program phases focused on R&D activities to address the critical technical issues and challenges at the cell level. A variety of cell and polymeric electrolyte concepts were pursued as part of the development efforts undertaken at numerous governmental, industrial and academic laboratories. Numerous candidate electrolyte materials were developed, synthesized and optimized for evaluation. Utilizing the component screening facility and the "standardized" test procedures developed at the NASA Glenn Research Center, electrochemical screening and performance evaluations of promising candidate materials were completed. This overview summarizes test results for a variety of candidate electrolyte materials that were developed under the PERS Program. Electrolyte properties are contrasted and compared to the original project goals, and the strengths and weaknesses of the electrolyte chemistries are discussed. Limited cycling data for full-cells using lithium metal and vanadium oxide electrodes are also presented. Based on measured electrolyte properties, the projected performance characteristics and temperature limitations of batteries utilizing the advanced electrolytes and components have been estimated. Limitations for the achievement of practical performance levels are also discussed, as well as needs for future research and development.

Improved performance and safety of lithium ion cells with the use of fluorinated carbonate-based electrolytes

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Ryan, V. S.; Surampudi, S.; Prakashi, G. K. S.; Hu, J.; Cheung, I.

2002-01-01

There has been increasing interest in developing lithium-ion electrolytes that possess enhanced safety characteristics, while still able to provide the desired stability and performance. Toward this end, our efforts have been focused on the development of lithium-ion electrolytes which contain partially and fully fluorinated carbonate solvents. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming Characteristics on carbon. Specifically, we have demonstrated the beneficial effect of electrolytes which contain the following fluorinated carbonate-based solvents: methyl 2,2,2-trifluoroethyl carbonate (MTFEC), ethyl-2,2,2 trifluoroethyl carbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl-2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (MHFPC), ethyl- 2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (EHFPC), and di-2,2,2-trifluoroethyl carbonate (DTFEC). These solvents have been incorporated into multi-component ternary and quaternary carbonate-based electrolytes and evaluated in lithium-carbon and carbon-LiNio.8Coo.202 cells (equipped with lithium reference electrodes). In addition to determining the charge/discharge behavior of these cells, a number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalatiodde-intercalation kinetics. In addition to their evaluation in experimental cells, cyclic voltammetry (CV) and conductivity measurements were performed on select electrolyte formulations to further our understanding of the trends in stability and ionic mobility imparted by different alkyl substituents in linear carbonates.

Understanding InP Nanowire Array Solar Cell Performance by Nanoprobe-Enabled Single Nanowire Measurements.

PubMed

Otnes, Gaute; Barrigón, Enrique; Sundvall, Christian; Svensson, K Erik; Heurlin, Magnus; Siefer, Gerald; Samuelson, Lars; Åberg, Ingvar; Borgström, Magnus T

2018-05-09

III-V solar cells in the nanowire geometry might hold significant synthesis-cost and device-design advantages as compared to thin films and have shown impressive performance improvements in recent years. To continue this development there is a need for characterization techniques giving quick and reliable feedback for growth development. Further, characterization techniques which can improve understanding of the link between nanowire growth conditions, subsequent processing, and solar cell performance are desired. Here, we present the use of a nanoprobe system inside a scanning electron microscope to efficiently contact single nanowires and characterize them in terms of key parameters for solar cell performance. Specifically, we study single as-grown InP nanowires and use electron beam induced current characterization to understand the charge carrier collection properties, and dark current-voltage characteristics to understand the diode recombination characteristics. By correlating the single nanowire measurements to performance of fully processed nanowire array solar cells, we identify how the performance limiting parameters are related to growth and/or processing conditions. We use this understanding to achieve a more than 7-fold improvement in efficiency of our InP nanowire solar cells, grown from a different seed particle pattern than previously reported from our group. The best cell shows a certified efficiency of 15.0%; the highest reported value for a bottom-up synthesized InP nanowire solar cell. We believe the presented approach have significant potential to speed-up the development of nanowire solar cells, as well as other nanowire-based electronic/optoelectronic devices.

Thickness dependences of solar cell performance

NASA Technical Reports Server (NTRS)

Sah, C. T.

1982-01-01

The significance of including factors such as the base resistivity loss for solar cells thicker than 100 microns and emitter and BSF layer recombination for thin cells in predicting the fill factor and efficiency of solar cells is demonstrated analytically. A model for a solar cell is devised with the inclusion of the dopant impurity concentration profile, variation of the electron and hole mobility with dopant concentration, the concentration and thermal capture and emission rates of the recombination center, device temperature, the AM1 spectra and the Si absorption coefficient. Device equations were solved by means of the transmission line technique. The analytical results were compared with those of low-level theory for cell performance. Significant differences in predictions of the fill factor resulted, and inaccuracies in the low-level approximations are discussed.

Edge Detection Based On the Characteristic of Primary Visual Cortex Cells

NASA Astrophysics Data System (ADS)

Zhu, M. M.; Xu, Y. L.; Ma, H. Q.

2018-01-01

Aiming at the problem that it is difficult to balance the accuracy of edge detection and anti-noise performance, and referring to the dynamic and static perceptions of the primary visual cortex (V1) cells, a V1 cell model is established to perform edge detection. A spatiotemporal filter is adopted to simulate the receptive field of V1 simple cells, the model V1 cell is obtained after integrating the responses of simple cells by half-wave rectification and normalization, Then the natural image edge is detected by using static perception of V1 cells. The simulation results show that, the V1 model can basically fit the biological data and has the universality of biology. What’s more, compared with other edge detection operators, the proposed model is more effective and has better robustness

Analytical Study on Multi-Tier 5G Heterogeneous Small Cell Networks: Coverage Performance and Energy Efficiency

PubMed Central

Xiao, Zhu; Liu, Hongjing; Havyarimana, Vincent; Li, Tong; Wang, Dong

2016-01-01

In this paper, we investigate the coverage performance and energy efficiency of multi-tier heterogeneous cellular networks (HetNets) which are composed of macrocells and different types of small cells, i.e., picocells and femtocells. By virtue of stochastic geometry tools, we model the multi-tier HetNets based on a Poisson point process (PPP) and analyze the Signal to Interference Ratio (SIR) via studying the cumulative interference from pico-tier and femto-tier. We then derive the analytical expressions of coverage probabilities in order to evaluate coverage performance in different tiers and investigate how it varies with the small cells’ deployment density. By taking the fairness and user experience into consideration, we propose a disjoint channel allocation scheme and derive the system channel throughput for various tiers. Further, we formulate the energy efficiency optimization problem for multi-tier HetNets in terms of throughput performance and resource allocation fairness. To solve this problem, we devise a linear programming based approach to obtain the available area of the feasible solutions. System-level simulations demonstrate that the small cells’ deployment density has a significant effect on the coverage performance and energy efficiency. Simulation results also reveal that there exits an optimal small cell base station (SBS) density ratio between pico-tier and femto-tier which can be applied to maximize the energy efficiency and at the same time enhance the system performance. Our findings provide guidance for the design of multi-tier HetNets for improving the coverage performance as well as the energy efficiency. PMID:27827917

Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

NASA Technical Reports Server (NTRS)

Baldwin, Richard S.

1987-01-01

The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

High Voltage LiNi0.5Mn1.5O4/Li4Ti5O12 Lithium Ion Cells at Elevated Temperatures: Carbonate- versus Ionic Liquid-Based Electrolytes.

PubMed

Cao, Xia; He, Xin; Wang, Jun; Liu, Haidong; Röser, Stephan; Rad, Babak Rezaei; Evertz, Marco; Streipert, Benjamin; Li, Jie; Wagner, Ralf; Winter, Martin; Cekic-Laskovic, Isidora

2016-10-05

Thanks to its high operating voltage, the LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel represents a promising next-generation cathode material candidate for Lithium ion batteries. However, LNMO-based full-cells with organic carbonate solvent electrolytes suffer from severe capacity fading issues, associated with electrolyte decomposition and concurrent degradative reactions at the electrode/electrolyte interface, especially at elevated temperatures. As promising alternatives, two selected LiTFSI/pyrrolidinium bis(trifluoromethane-sulfonyl)imide room temperature ionic liquid (RTIL) based electrolytes with inherent thermal stability were investigated in this work. Linear sweep voltammetry (LSV) profiles of the investigated LiTFSI/RTIL electrolytes display much higher oxidative stability compared to the state-of-the-art LiPF 6 /organic carbonate based electrolyte at elevated temperatures. Cycling performance of the LNMO/Li 4 Ti 5 O 12 (LTO) full-cells with LiTFSI/RTIL electrolytes reveals remarkable improvements with respect to capacity retention and Coulombic efficiency. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns indicate maintained pristine morphology and structure of LNMO particles after 50 cycles at 0.5C. The investigated LiTFSI/RTIL based electrolytes outperform the LiPF 6 /organic carbonate-based electrolyte in terms of cycling performance in LNMO/LTO full-cells at elevated temperatures.

Direct synthesis of vertically aligned ZnO nanowires on FTO substrates using a CVD method and the improvement of photovoltaic performance

PubMed Central

2012-01-01

In this work, we report a direct synthesis of vertically aligned ZnO nanowires on fluorine-doped tin oxide-coated substrates using the chemical vapor deposition (CVD) method. ZnO nanowires with a length of more than 30 μm were synthesized, and dye-sensitized solar cells (DSSCs) based on the as-grown nanowires were fabricated, which showed improvement of the device performance compared to those fabricated using transferred ZnO nanowires. Dependence of the cell performance on nanowire length and annealing temperature was also examined. This synthesis method provided a straightforward, one-step CVD process to grow relatively long ZnO nanowires and avoided subsequent nanowire transfer process, which simplified DSSC fabrication and improved cell performance. PMID:22673046

The investigation of optimal Silicon/Silicon(1-x)Germanium(x) thin-film solar cells with quantitative analysis

NASA Astrophysics Data System (ADS)

Ehsan, Md Amimul

Thin-film solar cells are emerging from the research laboratory to become commercially available devices for low cost electrical power generation applications. Silicon which is a cheap, abundant and non-toxic elemental semiconductor is an attractive candidate for these solar cells. Advanced modeling and simulation of Si thin-film solar cells has been performed to make this technology more cost effective without compromising the performance and efficiency. In this study, we focus on the design and optimization of Si/Si1-xGex heterostructures, and microcrystalline and nanocrystalline Si thin-film solar cells. Layer by layer optimization of these structures was performed by using advanced bandgap engineering followed by numerical analysis for their structural, electrical and optical characterizations. Special care has been introduced for the selection of material layers which can help to improve the light absorption properties of these structures for harvesting the solar spectrum. Various strategies such as the optimization of the doping concentrations, Ge contents in Si1-xGex buffer layer, incorporation of the absorber layers and surface texturing have been in used to improve overall conversion efficiencies of the solar cells. To be more specific, the observed improvement in the conversion efficiency of these solar cells has been calculated by tailoring the thickness of the buffer, absorber, and emitter layers. In brief, an approach relying on the phenomena of improved absorption of the buffer and absorber layer which leads to a corresponding gain in the open circuit voltage and short circuit current is explored. For numerical analysis, a PC1D simulator is employed that uses finite element analysis technique for solving semiconductor transport equations. A comparative study of the Si/Si1-xGex and Ge/Si1-xGex is also performed. We found that due to the higher lattice mismatch of Ge to Si, thin-film solar cells based on Si/Si1-xGex heterostructures performed much better. It has been found that microc-Si and nc-Si pin structures have strong dependence on their grain sizes and crystallinity to enhance the light absorption capability of these solar cells. Our results show that silicon based thin-film solar cells exhibit high level of performance making them very competitive for the next generation of low cost photovoltaic technology.

Naphthalene Diimide Based n-Type Conjugated Polymers as Efficient Cathode Interfacial Materials for Polymer and Perovskite Solar Cells.

PubMed

Jia, Tao; Sun, Chen; Xu, Rongguo; Chen, Zhiming; Yin, Qingwu; Jin, Yaocheng; Yip, Hin-Lap; Huang, Fei; Cao, Yong

2017-10-18

A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure-performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.

Harnessing Computational Biology for Exact Linear B-Cell Epitope Prediction: A Novel Amino Acid Composition-Based Feature Descriptor.

PubMed

Saravanan, Vijayakumar; Gautham, Namasivayam

2015-10-01

Proteins embody epitopes that serve as their antigenic determinants. Epitopes occupy a central place in integrative biology, not to mention as targets for novel vaccine, pharmaceutical, and systems diagnostics development. The presence of T-cell and B-cell epitopes has been extensively studied due to their potential in synthetic vaccine design. However, reliable prediction of linear B-cell epitope remains a formidable challenge. Earlier studies have reported discrepancy in amino acid composition between the epitopes and non-epitopes. Hence, this study proposed and developed a novel amino acid composition-based feature descriptor, Dipeptide Deviation from Expected Mean (DDE), to distinguish the linear B-cell epitopes from non-epitopes effectively. In this study, for the first time, only exact linear B-cell epitopes and non-epitopes have been utilized for developing the prediction method, unlike the use of epitope-containing regions in earlier reports. To evaluate the performance of the DDE feature vector, models have been developed with two widely used machine-learning techniques Support Vector Machine and AdaBoost-Random Forest. Five-fold cross-validation performance of the proposed method with error-free dataset and dataset from other studies achieved an overall accuracy between nearly 61% and 73%, with balance between sensitivity and specificity metrics. Performance of the DDE feature vector was better (with accuracy difference of about 2% to 12%), in comparison to other amino acid-derived features on different datasets. This study reflects the efficiency of the DDE feature vector in enhancing the linear B-cell epitope prediction performance, compared to other feature representations. The proposed method is made as a stand-alone tool available freely for researchers, particularly for those interested in vaccine design and novel molecular target development for systems therapeutics and diagnostics: https://github.com/brsaran/LBEEP.

PR01 Molecular Pathogenesis of Rickettsioses and Development of Anti-Rickettsial Treatment by Combinatorial Peptide-Based Libraries

DTIC Science & Technology

2006-02-01

likely reflecting similar cell death rates in all monolayers at late time points. By the end of the experiment at 120 hours, all monolayers showed a...50-55% increase in permeability when compared to the controls. 2. Cell death rates in rickettsiae-infected SV-HCEC monolayers In order to...necrotic cell death. Quantification of cell death was performed by determining the percent of total cells staining positive for PI. Cell death rates did

Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture.

PubMed

Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

2014-08-22

Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structure (LLTS) as a means of improving the light-harvesting capacity and performance of cells, achieving a 13.07% initial efficiency and greatly improved current output of a-Si:H single-junction solar cell based on this architecture. Given the unique transparency characteristics of thin-film solar cells, this proposed architecture has great potential for integration into the windows of buildings, microelectronics and other applications requiring transparent components.

Influence of silica matrix composition and functional component additives on the bioactivity and viability of encapsulated living cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savage, Travis J.; Dunphy, Darren R.; Harbaugh, Svetlana

The remarkable impact encapsulation matrix chemistry can have on the bioactivity and viability of integrated living cells is reported. Two silica chemistries (aqueous silicate and alkoxysilane), and a functional component additive (glycerol), are employed to generate three distinct silica matrices. These matrices are used to encapsulate living E. coli cells engineered with a synthetic riboswitch for cell-based biosensing. Following encapsulation, membrane integrity, reproductive capability, and riboswitch-based protein expression levels and rates are measured over a 5 week period. Striking differences in E. coli bioactivity, viability, and biosensing performance are observed for cells encapsulated within the different matrices. E. coli cellsmore » encapsulated for 35 days in aqueous silicate-based (AqS) matrices showed relatively low membrane integrity, but high reproductive capability in comparison to cells encapsulated in glycerol containing sodium silicate-based (AqS + g) and alkoxysilane-based (PGS) gels. Further, cells in sodium silicate-based matrices showed increasing fluorescence output over time, resulting in a 1.8-fold higher fluorescence level, and a faster expression rate, over cells free in solution. Furthermore, this unusual and unique combination of biological properties demonstrates that careful design of the encapsulation matrix chemistry can improve functionality of the biocomposite material, and result in new and unexpected physiological states.« less

Influence of silica matrix composition and functional component additives on the bioactivity and viability of encapsulated living cells

DOE PAGES

Savage, Travis J.; Dunphy, Darren R.; Harbaugh, Svetlana; ...

2015-11-06

The remarkable impact encapsulation matrix chemistry can have on the bioactivity and viability of integrated living cells is reported. Two silica chemistries (aqueous silicate and alkoxysilane), and a functional component additive (glycerol), are employed to generate three distinct silica matrices. These matrices are used to encapsulate living E. coli cells engineered with a synthetic riboswitch for cell-based biosensing. Following encapsulation, membrane integrity, reproductive capability, and riboswitch-based protein expression levels and rates are measured over a 5 week period. Striking differences in E. coli bioactivity, viability, and biosensing performance are observed for cells encapsulated within the different matrices. E. coli cellsmore » encapsulated for 35 days in aqueous silicate-based (AqS) matrices showed relatively low membrane integrity, but high reproductive capability in comparison to cells encapsulated in glycerol containing sodium silicate-based (AqS + g) and alkoxysilane-based (PGS) gels. Further, cells in sodium silicate-based matrices showed increasing fluorescence output over time, resulting in a 1.8-fold higher fluorescence level, and a faster expression rate, over cells free in solution. Furthermore, this unusual and unique combination of biological properties demonstrates that careful design of the encapsulation matrix chemistry can improve functionality of the biocomposite material, and result in new and unexpected physiological states.« less

Comparative study of the results from conventional cervico-vaginal oncotic cytology and liquid-based cytology.

PubMed

Stabile, Sueli Aparecida Batista; Evangelista, Dilson Henrique Ramos; Talamonte, Valdely Helena; Lippi, Umberto Gazi; Lopes, Reginaldo Guedes Coelho

2012-01-01

To compare two oncotic cervical cytology techniques, the conventional and the liquid-based cytology, in low risk patients for uterine cervical cancer. Comparative prospective study with 100 patients who came to their annual gynecological exam, and were submitted simultaneously to both techniques. We used the McNemar test, with a significance level of p < 0.05 to compare the results obtained related to adequacy of the smear quality, descriptive diagnosis prevalence, guided biopsy confirmation and histology. Adequacy of the smear was similar for both methods. The quality with squamocolumnar junction in 93% of conventional cytology and in 84% of the liquid-based cytology had statistical significance. As for the diagnosis of atypical cells they were detected in 3% of conventional cytology and in 10% of liquid-based cytology (p = 0.06). Atypical squamous cells of undetermined significance were the most prevalent abnormality. The liquid-based cytology performance was better when compared with colposcopy (guided biopsy), presenting sensitivity of 66.7% and specificity of 100%. There was no cytological and histological concordance for the conventional cytology. Liquid-based cytology had a better performance to diagnose atypical cells and the cytohistological concordance was higher than in the conventional cytology.

Influence of Electrode Design and Contacting Layers on Performance of Electrolyte Supported SOFC/SOEC Single Cells.

PubMed

Kusnezoff, Mihails; Trofimenko, Nikolai; Müller, Martin; Michaelis, Alexander

2016-11-08

The solid oxide cell is a basis for highly efficient and reversible electrochemical energy conversion. A single cell based on a planar electrolyte substrate as support (ESC) is often utilized for SOFC/SOEC stack manufacturing and fulfills necessary requirements for application in small, medium and large scale fuel cell and electrolysis systems. Thickness of the electrolyte substrate, and its ionic conductivity limits the power density of the ESC. To improve the performance of this cell type in SOFC/SOEC mode, alternative fuel electrodes, on the basis of Ni/CGO as well as electrolytes with reduced thickness, have been applied. Furthermore, different interlayers on the air side have been tested to avoid the electrode delamination and to reduce the cell degradation in electrolysis mode. Finally, the influence of the contacting layer on cell performance, especially for cells with an ultrathin electrolyte and thin electrode layers, has been investigated. It has been found that Ni/CGO outperform traditional Ni/8YSZ electrodes and the introduction of a ScSZ interlayer substantially reduces the degradation rate of ESC in electrolysis mode. Furthermore, it was demonstrated that, for thin electrodes, the application of contacting layers with good conductivity and adhesion to current collectors improves performance significantly.

Highly Efficient Plastic Crystal Ionic Conductors for Solid-state Dye-sensitized Solar Cells

PubMed Central

Hwang, Daesub; Kim, Dong Young; Jo, Seong Mu; Armel, Vanessa; MacFarlane, Douglas R.; Kim, Dongho; Jang, Sung-Yeon

2013-01-01

We have developed highly efficient, ambient temperature, solid-state ionic conductors (SSICs) for dye-sensitized solar cells (DSSCs) by doping a molecular plastic crystal, succinonitrile (SN), with trialkyl-substituted imidazolium iodide salts. High performance SSICs with enhanced ionic conductivity (2–4 mScm−1) were obtained. High performance solid-state DSSCs with power conversion efficiency of 7.8% were fabricated using our SSICs combined with unique hierarchically nanostructured TiO2 sphere (TiO2-SP) photoelectrodes; these electrodes have significant macroporosity, which assists penetration of the solid electrolyte into the electrode. The performance of our solid-state DSSCs is, to the best of our knowledge, the highest reported thus far for cells using plastic crystal-based SSICs, and is comparable to that of the state-of-the-art DSSCs which use ionic liquid type electrolytes. This report provides a logical strategy for the development of efficient plastic crystal-based SSICs for DSSCs and other electrochemical devices. PMID:24343425

Modulated CH3NH3PbI3−xBrx film for efficient perovskite solar cells exceeding 18%

PubMed Central

Tu, Yongguang; Wu, Jihuai; Lan, Zhang; He, Xin; Dong, Jia; Jia, Jinbiao; Guo, Panfeng; Lin, Jianming; Huang, Miaoliang; Huang, Yunfang

2017-01-01

The organic-inorganic lead halide perovskite layer is a crucial factor for the high performance perovskite solar cell (PSC). We introduce CH3NH3Br in the precursor solution to prepare CH3NH3PbI3−xBrx hybrid perovskite, and an uniform perovskite layer with improved crystallinity and apparent grain contour is obtained, resulting in the significant improvement of photovoltaic performance of PSCs. The effects of CH3NH3Br on the perovskite morphology, crystallinity, absorption property, charge carrier dynamics and device characteristics are discussed, and the improvement of open circuit voltage of the device depended on Br doping is confirmed. Based on above, the device based on CH3NH3PbI2.86Br0.14 exhibits a champion power conversion efficiency (PCE) of 18.02%. This study represents an efficient method for high-performance perovskite solar cell by modulating CH3NH3PbI3−xBrx film. PMID:28303938

TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell.

PubMed

Abdullah, M; Kamarudin, S K; Shyuan, L K

2016-12-01

In this study, TiO 2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm 2 (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

Improved Low-Temperature Performance of Li-Ion Cells Using New Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Buga, Ratnakumar V.; Gozdz, Antoni S.; Mani, Suresh

2010-01-01

As part of the continuing efforts to develop advanced electrolytes to improve the performance of lithium-ion cells, especially at low temperatures, a number of electrolyte formulations have been developed that result in improved low-temperature performance (down to 60 C) of 26650 A123Systems commercial lithium-ion cells. The cell type/design, in which the new technology has been demonstrated, has found wide application in the commercial sector (i.e., these cells are currently being used in commercial portable power tools). In addition, the technology is actively being considered for hybrid electric vehicle (HEV) and electric vehicle (EV) applications. In current work, a number of low-temperature electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed, which include the use of ternary mixtures of carbonates, the use of ester co-solvents [e.g., methyl butyrate (MB)], and optimized lithium salt concentrations (e.g., LiPF6), were compared with the commercial baseline electrolyte, as well as an electrolyte being actively considered for DoE HEV applications and previously developed by a commercial enterprise, namely LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC)(30:70%).

Direct alcohol fuel cells: Increasing platinum performance by modification with sp-group metals

NASA Astrophysics Data System (ADS)

Figueiredo, Marta C.; Sorsa, Olli; Doan, Nguyet; Pohjalainen, Elina; Hildebrand, Helga; Schmuki, Patrik; Wilson, Benjamin P.; Kallio, Tanja

2015-02-01

By using sp group metals as modifiers, the catalytic properties of Pt can be improved toward alcohols oxidation. In this work we report the performance increase of direct alcohol fuel cells (DAFC) fuelled with ethanol or 2-propanol with platinum based anode electrodes modified with Bi and Sb adatoms. For example, by simply adding Sb to the Pt/C based anode ink during membrane electrode assembly fabrication of a direct ethanol fuel cell (DEFC) its performance is improved three-fold, with more than 100 mV increase in the open circuit potential. For the fuel cell fuelled with 2-propanol high power densities are obtained at very high potentials with these catalyst materials suggesting a great improvement for practical applications. Particularly in the case of Pt/C-Bi, the improvement is such that within 0.6 V (from 0.7 to 0.1 V) the power densities are between 7 and 9 mW/cm2. The results obtained with these catalysts are in the same range as those obtained with other bimetallic catalysts comprising of PtRu and PtSn, which are currently considered to be the best for these type of fuel cells and that are obtained by more complicated (and consequently more expensive) methods.

Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

2016-05-01

In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm2, an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm2. Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells.

PubMed

Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

2016-05-17

In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm(2), an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm(2). Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: UTC FUEL CELLS' PC25C POWER PLANT - GAS PROCESSING UNIT PERFORMANCE FOR ANAEROBIC DIGESTER GAS

EPA Science Inventory

Under EPA’s Environmental Technology Verification program, which provides objective and scientific third party analysis of new technology that can benefit the environment, a combined heat and power system based on the UTC Fuel Cell's PC25C Fuel Cell Power Plant was evaluated. The...

Non-viable antagonist cells are associated with reduced biocontrol performance by viable cells of the yeast Papiliotrema flavescens against Fusarium head blight of wheat.

USDA-ARS?s Scientific Manuscript database

Microbially-based plant disease control products have achieved commercial market success, but the efficacy of such biocontrol products is sometimes deemed inconsistent. Improper processing of harvested microbial biomass or long-term storage can reduce the proportion of viable cells and necessitate t...

Calorimetric evaluation of commercial Ni-MH cells and charges

NASA Technical Reports Server (NTRS)

Darcy, Eric C.; Hughes, Brent M.

1995-01-01

The test objectives are to evaluate the electrical and thermal performance of commercial Ni-MH cells and to evaluate the effectiveness of commercial charge control circuits. The ultimate design objectives are to determine which cell designs are most suitable for scale-up and to guide the design of future Shuttle and Station based battery chargers.

Zero-CO2 emission and low-crossover 'rechargeable' PEM fuel cells using cyclohexane as an organic hydrogen reservoir.

PubMed

Kariya, Nobuko; Fukuoka, Atsushi; Ichikawa, Masaru

2003-03-21

High performance (open circuit voltage = 920 mV, maximum power density = 14-15 mW cm(-2)) of the PEM fuel cell was achieved by using cyclohexane as a fuel with zero-CO2 emission and lower-crossover through PEM than with a methanol-based fuel cell.

Reliability evaluation of high-performance, low-power FinFET standard cells based on mixed RBB/FBB technique

NASA Astrophysics Data System (ADS)

Wang, Tian; Cui, Xiaoxin; Ni, Yewen; Liao, Kai; Liao, Nan; Yu, Dunshan; Cui, Xiaole

2017-04-01

With shrinking transistor feature size, the fin-type field-effect transistor (FinFET) has become the most promising option in low-power circuit design due to its superior capability to suppress leakage. To support the VLSI digital system flow based on logic synthesis, we have designed an optimized high-performance low-power FinFET standard cell library based on employing the mixed FBB/RBB technique in the existing stacked structure of each cell. This paper presents the reliability evaluation of the optimized cells under process and operating environment variations based on Monte Carlo analysis. The variations are modelled with Gaussian distribution of the device parameters and 10000 sweeps are conducted in the simulation to obtain the statistical properties of the worst-case delay and input-dependent leakage for each cell. For comparison, a set of non-optimal cells that adopt the same topology without employing the mixed biasing technique is also generated. Experimental results show that the optimized cells achieve standard deviation reduction of 39.1% and 30.7% at most in worst-case delay and input-dependent leakage respectively while the normalized deviation shrinking in worst-case delay and input-dependent leakage can be up to 98.37% and 24.13%, respectively, which demonstrates that our optimized cells are less sensitive to variability and exhibit more reliability. Project supported by the National Natural Science Foundation of China (No. 61306040), the State Key Development Program for Basic Research of China (No. 2015CB057201), the Beijing Natural Science Foundation (No. 4152020), and Natural Science Foundation of Guangdong Province, China (No. 2015A030313147).

Clinical trials for stem cell transplantation: when are they needed?

PubMed

Van Pham, Phuc

2016-04-27

In recent years, both stem cell research and the clinical application of these promising cells have increased rapidly. About 1000 clinical trials using stem cells have to date been performed globally. More importantly, more than 10 stem cell-based products have been approved in some countries. With the rapid growth of stem cell applications, some countries have used clinical trials as a tool to diminish the rate of clinical stem cell applications. However, the point at which stem cell clinical trials are essential remains unclear. This commentary discusses when stem cell clinical trials are essential for stem cell transplantation therapies.

Design and fabrication of silver-hydrogen cells

NASA Technical Reports Server (NTRS)

Klein, M. G.

1975-01-01

The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

Association between shortage of energy supply and nuclear gene mutations leading to carcinomatous transformation.

PubMed

DU, Jianping

2016-01-01

Anaerobic bacteria use glycolysis, an oxygen-independent metabolic pathway, whereas energy metabolism in the evolved eukaryotic cell is performed via oxidative phosphorylation, with all eukaryotic cell activities depending upon high energy consumption. However, in cancer cells evolving from eukaryotic cells, the energy metabolism switches from oxidative phosphorylation to glycolysis. The shortage of energy supply induces cancer cells to acquire specific characteristics. Base pair renewal is the most energy-consuming process in the cell, and shortage of energy supply may lead to errors in this process; the more prominent the shortage in energy supply, the more errors are likely to occur in base pair renewal, resulting in gene mutations and expression of cancer cell characteristics. Thus, shortage of energy supply is associated with carcinomatous transformation.

Performance of glucose/O2 enzymatic fuel cell based on supporting electrodes over-coated by polymer-nanogold particle composite with entrapped enzymes

NASA Astrophysics Data System (ADS)

Huo, W. S.; Zeng, H.; Yang, Y.; Zhang, Y. H.

2017-03-01

Enzymatic electrodes over-coated by thin film of nano-composite made up of polymer and functionalized nano-gold particle was prepared. Glucose/O2 membrane-free enzymatic fuel cell based on nano-composite based electrodes with incorporated glucose oxidase and laccase was assembled. This enzymatic fuel cell exhibited high energy out-put density even when applied in human serum. Catalytic cycle involved in enzymatic fuel cell was limited by oxidation of glucose occurred on bioanode resulting from impact of sophisticated interaction between active site in glucose oxidase and nano-gold particle on configuration of redox center of enzyme molecule which crippled catalytic efficiency of redox protein.

Gas/Water and Heat Management of PEM-Based Fuel Cell and Electrolyzer Systems for Space Applications

NASA Astrophysics Data System (ADS)

Guo, Qing; Ye, Fang; Guo, Hang; Ma, Chong Fang

2017-02-01

Hydrogen/oxygen fuel cells were successfully utilized in the field of space applications to provide electric energy and potable water in human-rated space mission since the 1960s. Proton exchange membrane (PEM) based fuel cells, which provide high power/energy densities, were reconsidered as a promising space power equipment for future space exploration. PEM-based water electrolyzers were employed to provide life support for crews or as major components of regenerative fuel cells for energy storage. Gas/water and heat are some of the key challenges in PEM-based fuel cells and electrolytic cells, especially when applied to space scenarios. In the past decades, efforts related to gas/water and thermal control have been reported to effectively improve cell performance, stability lifespan, and reduce mass, volume and costs of those space cell systems. This study aimed to present a primary review of research on gas/water and waste thermal management for PEM-based electrochemical cell systems applied to future space explorations. In the fuel cell system, technologies related to reactant supplement, gas humidification, water removal and active/passive water separation were summarized in detail. Experimental studies were discussed to provide a direct understanding of the effect of the gas-liquid two-phase flow on product removal and mass transfer for PEM-based fuel cell operating in a short-term microgravity environment. In the electrolyzer system, several active and static passive phaseseparation methods based on diverse water supplement approaches were discussed. A summary of two advanced passive thermal management approaches, which are available for various sizes of space cell stacks, was specifically provided

Cell nuclei and cytoplasm joint segmentation using the sliding band filter.

PubMed

Quelhas, Pedro; Marcuzzo, Monica; Mendonça, Ana Maria; Campilho, Aurélio

2010-08-01

Microscopy cell image analysis is a fundamental tool for biological research. In particular, multivariate fluorescence microscopy is used to observe different aspects of cells in cultures. It is still common practice to perform analysis tasks by visual inspection of individual cells which is time consuming, exhausting and prone to induce subjective bias. This makes automatic cell image analysis essential for large scale, objective studies of cell cultures. Traditionally the task of automatic cell analysis is approached through the use of image segmentation methods for extraction of cells' locations and shapes. Image segmentation, although fundamental, is neither an easy task in computer vision nor is it robust to image quality changes. This makes image segmentation for cell detection semi-automated requiring frequent tuning of parameters. We introduce a new approach for cell detection and shape estimation in multivariate images based on the sliding band filter (SBF). This filter's design makes it adequate to detect overall convex shapes and as such it performs well for cell detection. Furthermore, the parameters involved are intuitive as they are directly related to the expected cell size. Using the SBF filter we detect cells' nucleus and cytoplasm location and shapes. Based on the assumption that each cell has the same approximate shape center in both nuclei and cytoplasm fluorescence channels, we guide cytoplasm shape estimation by the nuclear detections improving performance and reducing errors. Then we validate cell detection by gathering evidence from nuclei and cytoplasm channels. Additionally, we include overlap correction and shape regularization steps which further improve the estimated cell shapes. The approach is evaluated using two datasets with different types of data: a 20 images benchmark set of simulated cell culture images, containing 1000 simulated cells; a 16 images Drosophila melanogaster Kc167 dataset containing 1255 cells, stained for DNA and actin. Both image datasets present a difficult problem due to the high variability of cell shapes and frequent cluster overlap between cells. On the Drosophila dataset our approach achieved a precision/recall of 95%/69% and 82%/90% for nuclei and cytoplasm detection respectively and an overall accuracy of 76%.

Programmable and Multiparameter DNA-Based Logic Platform For Cancer Recognition and Targeted Therapy

PubMed Central

2014-01-01

The specific inventory of molecules on diseased cell surfaces (e.g., cancer cells) provides clinicians an opportunity for accurate diagnosis and intervention. With the discovery of panels of cancer markers, carrying out analyses of multiple cell-surface markers is conceivable. As a trial to accomplish this, we have recently designed a DNA-based device that is capable of performing autonomous logic-based analysis of two or three cancer cell-surface markers. Combining the specific target-recognition properties of DNA aptamers with toehold-mediated strand displacement reactions, multicellular marker-based cancer analysis can be realized based on modular AND, OR, and NOT Boolean logic gates. Specifically, we report here a general approach for assembling these modular logic gates to execute programmable and higher-order profiling of multiple coexisting cell-surface markers, including several found on cancer cells, with the capacity to report a diagnostic signal and/or deliver targeted photodynamic therapy. The success of this strategy demonstrates the potential of DNA nanotechnology in facilitating targeted disease diagnosis and effective therapy. PMID:25361164

Multiplexed Affinity-Based Separation of Proteins and Cells Using Inertial Microfluidics.

PubMed

Sarkar, Aniruddh; Hou, Han Wei; Mahan, Alison E; Han, Jongyoon; Alter, Galit

2016-03-30

Isolation of low abundance proteins or rare cells from complex mixtures, such as blood, is required for many diagnostic, therapeutic and research applications. Current affinity-based protein or cell separation methods use binary 'bind-elute' separations and are inefficient when applied to the isolation of multiple low-abundance proteins or cell types. We present a method for rapid and multiplexed, yet inexpensive, affinity-based isolation of both proteins and cells, using a size-coded mixture of multiple affinity-capture microbeads and an inertial microfluidic particle sorter device. In a single binding step, different targets-cells or proteins-bind to beads of different sizes, which are then sorted by flowing them through a spiral microfluidic channel. This technique performs continuous-flow, high throughput affinity-separation of milligram-scale protein samples or millions of cells in minutes after binding. We demonstrate the simultaneous isolation of multiple antibodies from serum and multiple cell types from peripheral blood mononuclear cells or whole blood. We use the technique to isolate low abundance antibodies specific to different HIV antigens and rare HIV-specific cells from blood obtained from HIV+ patients.

Electrochemical energy storage subsystems study, volume 1

NASA Technical Reports Server (NTRS)

Miller, F. Q.; Richardson, P. W.; Graff, C. L.; Jordan, M. V.; Patterson, V. L.

1981-01-01

The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models define baseline designs and costs. The major design and performance parameters are each varied to determine their influence on LCC around the baseline values.

High-Performance Semitransparent Perovskite Solar Cells with 10% Power Conversion Efficiency and 25% Average Visible Transmittance Based on Transparent CuSCN as the Hole-Transporting Material

DOE PAGES

Jung, Jae Woong; Chueh, Chu-Chen; Jen, Alex K. -Y.

2015-07-06

High-performance planar heterojunction perovskite (CH3NH3PbI3) solar cell (PVSC) is demonstrated by utilizing CuSCN as a hole-transporting layer. Efficient hole-transport and hole-extraction at the CuSCN/CH3NH3PbI3 interface facilitate the PVSCs to reach 16% power conversion efficiency (PCE). In addition, excellent transparency of CuSCN enables high-performance semitransparent PVSC (10% PCE and 25% average visible transmittance) to be realized.

Electrochemical Energy Storage Subsystems Study, Volume 2

NASA Technical Reports Server (NTRS)

Miller, F. Q.; Richardson, P. W.; Graff, C. L.; Jordan, M. V.; Patterson, V. L.

1981-01-01

The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models are exercised to define baseline designs and costs. Then the major design and performance parameters are each varied to determine their influence on LCC around the baseline values.

Pt-Ni and Pt-Co Catalyst Synthesis Route for Fuel Cell Applications

NASA Technical Reports Server (NTRS)

Firdosy, Samad A.; Ravi, Vilupanur A.; Valdez, Thomas I.; Kisor, Adam; Narayan, Sri R.

2013-01-01

Oxygen reduction reactions (ORRs) at the cathode are the rate-limiting step in fuel cell performance. The ORR is 100 times slower than the corresponding hydrogen oxidation at the anode. Speeding up the reaction at the cathode will improve fuel cell efficiency. The cathode material is generally Pt powder painted onto a substrate (e.g., graphite paper). Recent efforts in the fuel cell area have focused on replacing Pt with Pt-X alloys (where X = Co, Ni, Zr, etc.) in order to (a) reduce cost, and (b) increase ORR rates. One of these strategies is to increase ORR rates by reducing the powder size, which would result in an increase in the surface area, thereby facilitating faster reaction rates. In this work, a process has been developed that creates Pt-Ni or Pt-Co alloys that are finely divided (on the nano scale) and provide equivalent performance at lower Pt loadings. Lower Pt loadings will translate to lower cost. Precursor salts of the metals are dissolved in water and mixed. Next, the salt mixtures are dried on a hot plate. Finally, the dried salt mixture is heattreated in a furnace under flowing reducing gas. The catalyst powder is then used to fabricate a membrane electrode assembly (MEA) for electrochemical performance testing. The Pt- Co catalyst-based MEA showed comparable performance to an MEA fabri cated using a standard Pt black fuel cell catalyst. The main objective of this program has been to increase the overall efficiencies of fuel cell systems to support power for manned lunar bases. This work may also have an impact on terrestrial programs, possibly to support the effort to develop a carbon-free energy source. This catalyst can be used to fabricate high-efficiency fuel cell units that can be used in space as regenerative fuel cell systems, and terrestrially as primary fuel cells. Terrestrially, this technology will become increasingly important when transition to a hydrogen economy occurs.

Feasibility study of stain-free classification of cell apoptosis based on diffraction imaging flow cytometry and supervised machine learning techniques.

PubMed

Feng, Jingwen; Feng, Tong; Yang, Chengwen; Wang, Wei; Sa, Yu; Feng, Yuanming

2018-06-01

This study was to explore the feasibility of prediction and classification of cells in different stages of apoptosis with a stain-free method based on diffraction images and supervised machine learning. Apoptosis was induced in human chronic myelogenous leukemia K562 cells by cis-platinum (DDP). A newly developed technique of polarization diffraction imaging flow cytometry (p-DIFC) was performed to acquire diffraction images of the cells in three different statuses (viable, early apoptotic and late apoptotic/necrotic) after cell separation through fluorescence activated cell sorting with Annexin V-PE and SYTOX® Green double staining. The texture features of the diffraction images were extracted with in-house software based on the Gray-level co-occurrence matrix algorithm to generate datasets for cell classification with supervised machine learning method. Therefore, this new method has been verified in hydrogen peroxide induced apoptosis model of HL-60. Results show that accuracy of higher than 90% was achieved respectively in independent test datasets from each cell type based on logistic regression with ridge estimators, which indicated that p-DIFC system has a great potential in predicting and classifying cells in different stages of apoptosis.

Performance Enhancement of Polymer Solar Cells by Using Two Polymer Donors with Complementary Absorption Spectra.

PubMed

Lu, Heng; Zhang, Xuejuan; Li, Cuihong; Wei, Hedi; Liu, Qian; Li, Weiwei; Bo, Zhishan

2015-07-01

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-cell genomic profiling of acute myeloid leukemia for clinical use: A pilot study

PubMed Central

Yan, Benedict; Hu, Yongli; Ban, Kenneth H.K.; Tiang, Zenia; Ng, Christopher; Lee, Joanne; Tan, Wilson; Chiu, Lily; Tan, Tin Wee; Seah, Elaine; Ng, Chin Hin; Chng, Wee-Joo; Foo, Roger

2017-01-01

Although bulk high-throughput genomic profiling studies have led to a significant increase in the understanding of cancer biology, there is increasing awareness that bulk profiling approaches do not completely elucidate tumor heterogeneity. Single-cell genomic profiling enables the distinction of tumor heterogeneity, and may improve clinical diagnosis through the identification and characterization of putative subclonal populations. In the present study, the challenges associated with a single-cell genomics profiling workflow for clinical diagnostics were investigated. Single-cell RNA-sequencing (RNA-seq) was performed on 20 cells from an acute myeloid leukemia bone marrow sample. Putative blasts were identified based on their gene expression profiles and principal component analysis was performed to identify outlier cells. Variant calling was performed on the single-cell RNA-seq data. The present pilot study demonstrates a proof of concept for clinical single-cell genomic profiling. The recognized limitations include significant stochastic RNA loss and the relatively low throughput of the current proposed platform. Although the results of the present study are promising, further technological advances and protocol optimization are necessary for single-cell genomic profiling to be clinically viable. PMID:28454300

Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Mönnighoff, Xaver; Börner, Markus; Haetge, Jan; Schappacher, Falko M.; Winter, Martin

2017-02-01

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O2 (NCM532)/graphite, were aged at 20 °C and 45 °C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 °C show a better electrochemical performance over lifetime than the cells cycled at 20 °C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 °C differ strongly at contrast to cells cycled at 20 °C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed.

Label-free high-throughput imaging flow cytometry

NASA Astrophysics Data System (ADS)

Mahjoubfar, A.; Chen, C.; Niazi, K. R.; Rabizadeh, S.; Jalali, B.

2014-03-01

Flow cytometry is an optical method for studying cells based on their individual physical and chemical characteristics. It is widely used in clinical diagnosis, medical research, and biotechnology for analysis of blood cells and other cells in suspension. Conventional flow cytometers aim a laser beam at a stream of cells and measure the elastic scattering of light at forward and side angles. They also perform single-point measurements of fluorescent emissions from labeled cells. However, many reagents used in cell labeling reduce cellular viability or change the behavior of the target cells through the activation of undesired cellular processes or inhibition of normal cellular activity. Therefore, labeled cells are not completely representative of their unaltered form nor are they fully reliable for downstream studies. To remove the requirement of cell labeling in flow cytometry, while still meeting the classification sensitivity and specificity goals, measurement of additional biophysical parameters is essential. Here, we introduce an interferometric imaging flow cytometer based on the world's fastest continuous-time camera. Our system simultaneously measures cellular size, scattering, and protein concentration as supplementary biophysical parameters for label-free cell classification. It exploits the wide bandwidth of ultrafast laser pulses to perform blur-free quantitative phase and intensity imaging at flow speeds as high as 10 meters per second and achieves nanometer-scale optical path length resolution for precise measurements of cellular protein concentration.

Graphene nanoplatelet doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance

NASA Astrophysics Data System (ADS)

Aïssa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J.; Essehli, Rachid; Mahmoud, Khaled A.

2018-03-01

Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date—in particular the low power conversion efficiency (PCE)—has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm-2, a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp2-bonded carbon therein.

Graphene nanoplatelet doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance.

PubMed

Aïssa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J; Essehli, Rachid; Mahmoud, Khaled A

2018-01-31

Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date-in particular the low power conversion efficiency (PCE)-has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm -2 , a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp 2 -bonded carbon therein.

Graphene nanoplatelets doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance.

PubMed

Aissa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J; Essehli, Rachid; Mahmoud, Khaled

2018-01-09

Hybrid organic photovoltaic (OPV) cells based on conjugated polymers photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing, and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date -in particular the low power conversion efficiency (PCE)- has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells has been mainly attributed to low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material can be an excellent candidate for assisting the charge transport improvement in the active layer of OPV cells due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of optoelectronic properties and photovoltaic performance of graphene nanoplatelets (GNP) doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic photovoltaic based device, using PEDOT:PSS on ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP contents while the photoluminescence showed a clear quenching, indicating electrons transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer has resulted in enhanced PV performance with respect to a reference cell, and the best PV performances were obtained with 3 wt. % of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA/cm2, a fill factor of 47.12 %, and a power conversion efficiency of about 3.61 %. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp2-bonded carbon therein. © 2018 IOP Publishing Ltd.

Pancreatic tumor detection using hypericin-based fluorescence spectroscopy and cytology

NASA Astrophysics Data System (ADS)

Lavu, Harish; Geary, Kevin; Fetterman, Harold R.; Saxton, Romaine E.

2005-04-01

Hypericin is a novel, highly fluorescent photosensitizer that exhibits selective tumor cell uptake properties and is particularly resistant to photobleaching. In this study, we have characterized hypericin uptake in human pancreatic tumor cells with relation to incubation time, cell number, and drug concentration. Ex vivo hypericin based fluorescence spectroscopy was performed to detect the presence of MIA PaCa-2 pancreatic tumor cells in the peritoneal cavity of BALB/c nude mice, as well as to quantify gross tumor burden. Hypericin based cytology of peritoneal lavage samples, using both one and two photon laser confocal microscopy, demonstrated more than a two-fold increase in fluorescence emission of pancreatic tumor cells as compared to control samples. In vitro treatment of pancreatic cancer cells with hypericin based photodynamic therapy showed tumor cell cytotoxicity in a drug dose, incident laser power, and time dependent manner. For these experiments, a continuous wavelength solid-state laser source (532 nm) was operated at power levels in the range of 100-400 mW. Potential applications of hypericin in tumor diagnosis, staging, and therapy will be presented.

Toxicological evaluation of Cd-based fluorescent nanoprobes by means of in vivo studies

NASA Astrophysics Data System (ADS)

Farias, Patricia M. A.; Ma-Hock, Lan; Landsiedel, Robert; van Ravenzwaay, Bennard

2018-02-01

Cadmium still represents a stigma for many research- and/or industrial applications. Some deleterious effects are attributed to Cadmium. In the present work, highly fluorescent Cadmium sulfide quantum dots are investigated by e.g. physical-chemical characterization. Most important however is their application as fluorescent probes for bio-imaging in living cells and tissues. This work presents their toxicological evaluation by means of in vivo studies. Bio-imaging experiments are performed without any pre-treatment. The toxicological studies performed, strongly indicate that the use of Cadmium based nanoparticles as fluorescent probes may be nonhazardous and not induce side effects for cells/tissues.

Combinatorial high-throughput optical screening of high performance Pd alloy cathode for hybrid Li-air battery.

PubMed

Jun, Young Jin; Park, Sung Hyeon; Woo, Seong Ihl

2014-12-08

Combinatorial high-throughput optical screening method was developed to find the optimum composition of highly active Pd-based catalysts at the cathode of the hybrid Li-air battery. Pd alone, which is one-third the cost of Pt, has difficulty in replacing Pt; therefore, the integration of other metals was investigated to improve its performance toward oxygen reduction reaction (ORR). Among the binary Pd-based catalysts, the composition of Pd-Ir derived catalysts had higher performance toward ORR compared to other Pd-based binary combinations. The composition at 88:12 at. % (Pd: Ir) showed the highest activity toward ORR at the cathode of the hybrid Li-air battery. The prepared Pd(88)Ir(12)/C catalyst showed a current density of -2.58 mA cm(-2) at 0.8 V (vs RHE), which was around 30% higher compared to that of Pd/C (-1.97 mA cm(-2)). When the prepared Pd(88)Ir(12)/C catalyst was applied to the hybrid Li-air battery, the polarization of the cell was reduced and the energy efficiency of the cell was about 30% higher than that of the cell with Pd/C.

Mathematical analysis and coordinated current allocation control in battery power module systems

NASA Astrophysics Data System (ADS)

Han, Weiji; Zhang, Liang

2017-12-01

As the major energy storage device and power supply source in numerous energy applications, such as solar panels, wind plants, and electric vehicles, battery systems often face the issue of charge imbalance among battery cells/modules, which can accelerate battery degradation, cause more energy loss, and even incur fire hazard. To tackle this issue, various circuit designs have been developed to enable charge equalization among battery cells/modules. Recently, the battery power module (BPM) design has emerged to be one of the promising solutions for its capability of independent control of individual battery cells/modules. In this paper, we propose a new current allocation method based on charging/discharging space (CDS) for performance control in BPM systems. Based on the proposed method, the properties of CDS-based current allocation with constant parameters are analyzed. Then, real-time external total power requirement is taken into account and an algorithm is developed for coordinated system performance control. By choosing appropriate control parameters, the desired system performance can be achieved by coordinating the module charge balance and total power efficiency. Besides, the proposed algorithm has complete analytical solutions, and thus is very computationally efficient. Finally, the efficacy of the proposed algorithm is demonstrated using simulations.

Interaction of nickel-based SOFC anodes with trace contaminants from coal-derived synthesis gas

NASA Astrophysics Data System (ADS)

Hackett, Gregory Allen

New and efficient methods of producing electrical energy from natural resources have become an important topic for researchers. Integrated gasification and fuel cell (IGFC) systems offer a fuel-flexible, high-efficiency method of energy generation. Specifically, in coal gasification processes, coal can be changed into a high-quality gaseous fuel suitable for feeding solid oxide fuel cells (SOFCs). However, trace species found in coal synthesis gas (syngas) may have a deleterious effect on the performance of nickel-based SOFC anodes. Generally, the cost of removing these species down to parts per million (ppm) levels is high. The purpose of this research is to determine the highest amount of contaminant that results in a low rate (˜1% per 1000 h) of cell performance degradation, allowing the SOFC to produce usable power for 40,000 hours. The cell performance degradation rate was determined for benzene, naphthalene, and mercury-doped syngas based on species concentration. Experimental data are fitted with degradation models to predict cell lifetime behavior. From these results, the minimum coal syngas cleanup required for these trace materials is determined. It is found that for a final cell voltage of 0.6 V, naphthalene and benzene must be cleaned to 360 ppm and less than 150 ppm, respectively. No additional cleaning is required for mercury beyond established environmental standards. Additionally, a detailed attack and recovery mechanism is proposed for the hydrocarbon species and their interaction with the fuel cell. This mechanism is proposed by considering the type of degradation models predicted and how carbon would interact with the Ni-YSZ anode to justify those models. The mechanism postulates that carbon is diffusing into the nickel structure, creating a metal solution. Once the nickel is saturated, the carbon begins to deposit on the nickel surface, reducing the electrode active area. The formation of metal solutions and the deposition of carbon results in reduced cell productivity.

Electron-transporting small molecule/ o-xylene hybrid additives to boost the performance of simplified inverted polymer solar cells

NASA Astrophysics Data System (ADS)

Qin, Dashan; Cao, Huan; Zhang, Jidong

2017-05-01

Electron-transporting small molecule bathophenanthroline (Bphen) together with o-xylene has been used as hybrid additives to improve the performance of simplified inverted polymer solar cells employing ITO alone as cathode and photoactive layer based on polymer [[2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b] dithiophene] [3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

A series of simple oligomer-like small molecules based on oligothiophenes for solution-processed solar cells with high efficiency.

PubMed

Kan, Bin; Li, Miaomiao; Zhang, Qian; Liu, Feng; Wan, Xiangjian; Wang, Yunchuang; Ni, Wang; Long, Guankui; Yang, Xuan; Feng, Huanran; Zuo, Yi; Zhang, Mingtao; Huang, Fei; Cao, Yong; Russell, Thomas P; Chen, Yongsheng

2015-03-25

A series of acceptor-donor-acceptor simple oligomer-like small molecules based on oligothiophenes, namely, DRCN4T-DRCN9T, were designed and synthesized. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated. Except for DRCN4T, excellent performances were obtained for DRCN5T-DRCN9T. The devices based on DRCN5T, DRCN7T, and DRCN9T with axisymmetric chemical structures exhibit much higher short-circuit current densities than those based on DRCN6T and DRCN8T with centrosymmetric chemical structures, which is attributed to their well-developed fibrillar network with a feature size less than 20 nm. The devices based on DRCN5T/PC71BM showed a notable certified power conversion efficiency (PCE) of 10.10% under AM 1.5G irradiation (100 mW cm(-2)) using a simple solution spin-coating fabrication process. This is the highest PCE for single-junction small-molecule-based organic photovoltaics (OPVs) reported to date. DRCN5T is a rather simpler molecule compared with all of the other high-performance molecules in OPVs to date, and this might highlight its advantage in the future possible commercialization of OPVs. These results demonstrate that a fine and balanced modification/design of chemical structure can make significant performance differences and that the performance of solution-processed small-molecule-based solar cells can be comparable to or even surpass that of their polymer counterparts.

Fuzzy control based engine sizing optimization for a fuel cell/battery hybrid mini-bus

NASA Astrophysics Data System (ADS)

Kim, Minjin; Sohn, Young-Jun; Lee, Won-Yong; Kim, Chang-Soo

The fuel cell/battery hybrid vehicle has been focused for the alternative engine of the existing internal-combustion engine due to the following advantages of the fuel cell and the battery. Firstly, the fuel cell is highly efficient and eco-friendly. Secondly, the battery has the fast response for the changeable power demand. However, the competitive efficiency of the hybrid fuel cell vehicle is necessary to successfully alternate the conventional vehicles with the fuel cell hybrid vehicle. The most relevant factor which affects the overall efficiency of the hybrid fuel cell vehicle is the relative engine sizing between the fuel cell and the battery. Therefore the design method to optimize the engine sizing of the fuel cell hybrid vehicle has been proposed. The target system is the fuel cell/battery hybrid mini-bus and its power distribution is controlled based on the fuzzy logic. The optimal engine sizes are determined based on the simulator developed in this paper. The simulator includes the several models for the fuel cell, the battery, and the major balance of plants. After the engine sizing, the system efficiency and the stability of the power distribution are verified based on the well-known driving schedule. Consequently, the optimally designed mini-bus shows good performance.

White blood cells identification system based on convolutional deep neural learning networks.

PubMed

Shahin, A I; Guo, Yanhui; Amin, K M; Sharawi, Amr A

2017-11-16

White blood cells (WBCs) differential counting yields valued information about human health and disease. The current developed automated cell morphology equipments perform differential count which is based on blood smear image analysis. Previous identification systems for WBCs consist of successive dependent stages; pre-processing, segmentation, feature extraction, feature selection, and classification. There is a real need to employ deep learning methodologies so that the performance of previous WBCs identification systems can be increased. Classifying small limited datasets through deep learning systems is a major challenge and should be investigated. In this paper, we propose a novel identification system for WBCs based on deep convolutional neural networks. Two methodologies based on transfer learning are followed: transfer learning based on deep activation features and fine-tuning of existed deep networks. Deep acrivation featues are extracted from several pre-trained networks and employed in a traditional identification system. Moreover, a novel end-to-end convolutional deep architecture called "WBCsNet" is proposed and built from scratch. Finally, a limited balanced WBCs dataset classification is performed through the WBCsNet as a pre-trained network. During our experiments, three different public WBCs datasets (2551 images) have been used which contain 5 healthy WBCs types. The overall system accuracy achieved by the proposed WBCsNet is (96.1%) which is more than different transfer learning approaches or even the previous traditional identification system. We also present features visualization for the WBCsNet activation which reflects higher response than the pre-trained activated one. a novel WBCs identification system based on deep learning theory is proposed and a high performance WBCsNet can be employed as a pre-trained network. Copyright © 2017. Published by Elsevier B.V.

Ionic Liquid Hybrid Electrolytes for Lithium-Ion Batteries: A Key Role of the Separator-Electrolyte Interface in Battery Electrochemistry.

PubMed

Huie, Matthew M; DiLeo, Roberta A; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2015-06-10

Batteries are multicomponent systems where the theoretical voltage and stoichiometric electron transfer are defined by the electrochemically active anode and cathode materials. While the electrolyte may not be considered in stoichiometric electron-transfer calculations, it can be a critical factor determining the deliverable energy content of a battery, depending also on the use conditions. The development of ionic liquid (IL)-based electrolytes has been a research area of recent reports by other researchers, due, in part, to opportunities for an expanded high-voltage operating window and improved safety through the reduction of flammable solvent content. The study reported here encompasses a systematic investigation of the physical properties of IL-based hybrid electrolytes including quantitative characterization of the electrolyte-separator interface via contact-angle measurements. An inverse trend in the conductivity and wetting properties was observed for a series of IL-based electrolyte candidates. Test-cell measurements were undertaken to evaluate the electrolyte performance in the presence of functioning anode and cathode materials, where several promising IL-based hybrid electrolytes with performance comparable to that of conventional carbonate electrolytes were identified. The study revealed that the contact angle influenced the performance more significantly than the conductivity because the cells containing IL-tetrafluoroborate-based electrolytes with higher conductivity but poorer wetting showed significantly decreased performance relative to the cells containing IL-bis(trifluoromethanesulfonyl)imide electrolytes with lower conductivity but improved wetting properties. This work contributes to the development of new IL battery-based electrolyte systems with the potential to improve the deliverable energy content as well as safety of lithium-ion battery systems.

A High-Performance and Recyclable Al-Air Coin Cell Based on Eco-Friendly Chitosan Hydrogel Membranes.

PubMed

Liu, Yisi; Sun, Qian; Yang, Xiaofei; Liang, Jianneng; Wang, Biqiong; Koo, Alicia; Li, Ruying; Li, Jie; Sun, Xueliang

2018-05-18

Aluminum-air batteries are a promising power supply for electronics due to its low cost and high energy density. However, portable coin-type Al-air batteries operating under ambient air condition for small electronic appliances have rarely been reported. Herein, coin cell-type Al-air batteries using cost-effective and eco-friendly chitosan hydrogel membranes modified by SiO2, SnO2, and ZnO have been prepared and assembled. The Al-air coin cell employing chitosan hydrogel membrane containing 10 wt.% SiO2 as a separator exhibits better discharge performance with a higher flat voltage plateau, longer discharge duration, and higher power density than the cells using a chitosan hydrogel membrane containing SnO2 or ZnO. Moreover, we also demonstrate that the presented Al-air coin cell can be recycled by a series of eco-friendly procedures using food grade ingredients, resulting in recycled products that are environmentally safe and ready for reuse. The Al-air coin cell adopting a recycled cathode from a fully discharged Al-air coin cell using the above-mentioned procedure has shown comparable performance to cells assembled with a new cathode. With these merits of enhanced electrochemical performance and recyclability, this new Al-air coin cell with modified chitosan hydrogel membrane can find wide applications for powering portable and small-size electronics.

Heat transfer enhancement in a lithium-ion cell through improved material-level thermal transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vishwakarma, Vivek; Waghela, Chirag; Wei, Zi

2016-09-25

We report that while Li-ion cells offer excellent electrochemical performance for several applications including electric vehicles, they also exhibit poor thermal transport characteristics, resulting in reduced performance, overheating and thermal runaway. Inadequate heat removal from Li-ion cells originates from poor thermal conductivity within the cell. This paper identifies the rate-limiting material-level process that dominates overall thermal conduction in a Li-ion cell. Results indicate that thermal characteristics of a Li-ion cell are largely dominated by heat transfer across the cathode-separator interface rather than heat transfer through the materials themselves. This interfacial thermal resistance contributes around 88% of total thermal resistance inmore » the cell. Measured value of interfacial resistance is close to that obtained from theoretical models that account for weak adhesion and large acoustic mismatch between cathode and separator. Further, to address this problem, an amine-based chemical bridging of the interface is carried out. This is shown to result in in four-times lower interfacial thermal resistance without deterioration in electrochemical performance, thereby increasing effective thermal conductivity by three-fold. This improvement is expected to reduce peak temperature rise during operation by 60%. Finally, by identifying and addressing the material-level root cause of poor thermal transport in Li-ion cells, this work may contribute towards improved thermal performance of Li-ion cells.« less

Stability study of cermet-supported solid oxide fuel cells with bi-layered electrolyte

NASA Astrophysics Data System (ADS)

Zhang, Xinge; Gazzarri, Javier; Robertson, Mark; Decès-Petit, Cyrille; Kesler, Olivera

Performance and stability of five cermet-supported button-type solid oxide fuel cells featuring a bi-layered electrolyte (SSZ/SDC), an SSC cathode, and a Ni-SSZ anode, were analyzed using polarization curves, impedance spectroscopy, and post-mortem SEM observation. The cell performance degradation at 650 °C in H 2/air both with and without DC bias conditions was manifested primarily as an increase in polarization resistance, approximately at a rate of 2.3 mΩ cm 2 h -1 at OCV, suggesting a decrease in electrochemical kinetics as the main phenomenon responsible for the performance decay. In addition, the initial series resistance was about ten times higher than the calculated resistance corresponding to the electrolyte, reflecting a possible inter-reaction between the electrolyte layers that occurred during the sintering stage. In situ and ex situ sintered cathodes showed no obvious difference in cell performance or decay rate. The stability of the cells with and without electrical load was also investigated and no significant influence of DC bias was recorded. Based on the experimental results presented, we preliminarily attribute the performance degradation to electrochemical and microstructural degradation of the cathode.

Performance and properties of anodes reinforced with metal oxide nanoparticles for molten carbonate fuel cells

NASA Astrophysics Data System (ADS)

Accardo, Grazia; Frattini, Domenico; Yoon, Sung Pil; Ham, Hyung Chul; Nam, Suk Woo

2017-12-01

Development of electrode materials for molten carbonate fuel cells is a fundamental issue as a balance between mechanical and electrochemical properties is required due to the particular operating environments of these cells. As concern the anode, a viable strategy is to use nano-reinforced particles during electrodes' fabrication. Candidate nanomaterials comprise, but are not limited to, ZrO2, CeO2, TiO2, Ti, Mg, Al, etc. This work deals with the characterization and test of two different types of hard oxide nanoparticles as reinforce for NiAl-based anodes in molten carbonate fuel cells. Nano ceria and nano zirconia are compared each other and single cell test performances are presented. Compared to literature, the use of hard metal oxide nanoparticles allows good performance and promising perspectives with respect to the use a third alloying metal. However, nano zirconia performed slightly better than nano ceria as polarization and power curves are higher even if nano ceria has the highest mechanical properties. This means that the choice of nanoparticles to obtain improved anodes performance and properties is not trivial and a trade-off between relevant properties plays a key role.

Production of oncolytic adenovirus and human mesenchymal stem cells in a single-use, Vertical-Wheel bioreactor system: Impact of bioreactor design on performance of microcarrier-based cell culture processes.

PubMed

Sousa, Marcos F Q; Silva, Marta M; Giroux, Daniel; Hashimura, Yas; Wesselschmidt, Robin; Lee, Brian; Roldão, António; Carrondo, Manuel J T; Alves, Paula M; Serra, Margarida

2015-01-01

Anchorage-dependent cell cultures are used for the production of viruses, viral vectors, and vaccines, as well as for various cell therapies and tissue engineering applications. Most of these applications currently rely on planar technologies for the generation of biological products. However, as new cell therapy product candidates move from clinical trials towards potential commercialization, planar platforms have proven to be inadequate to meet large-scale manufacturing demand. Therefore, a new scalable platform for culturing anchorage-dependent cells at high cell volumetric concentrations is urgently needed. One promising solution is to grow cells on microcarriers suspended in single-use bioreactors. Toward this goal, a novel bioreactor system utilizing an innovative Vertical-Wheel™ technology was evaluated for its potential to support scalable cell culture process development. Two anchorage-dependent human cell types were used: human lung carcinoma cells (A549 cell line) and human bone marrow-derived mesenchymal stem cells (hMSC). Key hydrodynamic parameters such as power input, mixing time, Kolmogorov length scale, and shear stress were estimated. The performance of Vertical-Wheel bioreactors (PBS-VW) was then evaluated for A549 cell growth and oncolytic adenovirus type 5 production as well as for hMSC expansion. Regarding the first cell model, higher cell growth and number of infectious viruses per cell were achieved when compared with stirred tank (ST) bioreactors. For the hMSC model, although higher percentages of proliferative cells could be reached in the PBS-VW compared with ST bioreactors, no significant differences in the cell volumetric concentration and expansion factor were observed. Noteworthy, the hMSC population generated in the PBS-VW showed a significantly lower percentage of apoptotic cells as well as reduced levels of HLA-DR positive cells. Overall, these results showed that process transfer from ST bioreactor to PBS-VW, and scale-up was successfully carried out for two different microcarrier-based cell cultures. Ultimately, the data herein generated demonstrate the potential of Vertical-Wheel bioreactors as a new scalable biomanufacturing platform for microcarrier-based cell cultures of complex biopharmaceuticals. © 2015 American Institute of Chemical Engineers.

Model Comparisons For Space Solar Cell End-Of-Life Calculations

NASA Astrophysics Data System (ADS)

Messenger, Scott; Jackson, Eric; Warner, Jeffrey; Walters, Robert; Evans, Hugh; Heynderickx, Daniel

2011-10-01

Space solar cell end-of-life (EOL) calculations are performed over a wide range of space radiation environments for GaAs-based single and multijunction solar cell technologies. Two general semi-empirical approaches will used to generate these EOL calculation results: 1) the JPL equivalent fluence (EQFLUX) and 2) the NRL displacement damage dose (SCREAM). This paper also includes the first results using the Monte Carlo-based version of SCREAM, called MC- SCREAM, which is now freely available online as part of the SPENVIS suite of programs.

Performances and impedance spectroscopy of Small-molecule bulk heterojunction solar cells based on PtOEP: PCBM

NASA Astrophysics Data System (ADS)

Abuelwafa, A. A.; Dongol, M.; El-Nahass, M. M.; Soga, T.

2018-03-01

Small-molecule bulk heterojunction (SBHJ) solar cells based on platinum octaethylporphyrin (PtOEP) as donor material and phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor were fabricated using spin coating techniques with weight ratios from 1:0.1 to 1:9. The formation of charge transfer complex CTC in the PtOEP: PCBM blend was specified from the redshift of the PtOEP absorption peak after blending with PCBM. The photovoltaic performance for PtOEP: PCBM blends were investigated using the external quantum efficiency (EQE) besides the current density-voltage (J-V) characteristics under illumination100 mW/cm2 (AM1.5G). The BHJ solar cell with PtOEP: PCBM ratio of 1:9 exhibited the best performance. The impedance spectroscopy (IS) was examined in the frequency range from 25 Hz to 1 MHz. The equivalent circuit model was evaluated in details to evaluate the impedance spectroscopy parameters. Dielectric constant {ɛ ^' }, dielectric loss {ɛ ^' ' }} and dielectric modulus were included and discussed in terms of dielectric polarization processes. Dielectric modulus displays the non-Debye relaxation in PtOEP: PCBM BHJ solar cells.

Fabrication of high-performance supercapacitors based on transversely oriented carbon nanotubes

NASA Astrophysics Data System (ADS)

Markoulidis, F.; Lei, C.; Lekakou, C.

2013-04-01

High-performance supercapacitors with organic electrolyte 1 M TEABF4 (tetraethyl ammonium tetrafluoroborate) in PC (propylene carbonate) were fabricated and tested, based on multiwall carbon nanotubes (MWNTs) deposited by electrophoresis on three types of alternative substrates: aluminium foil, ITO (indium tin oxide) coated PET (polyethylene terephthalate) film and PET film. In all cases, SEM (scanning electron microscopy) and STEM (scanning transmission electron microscopy) micrographs demonstrated that protruding, transversely oriented MWNT structures were formed, which should increase the transverse conductivity of these MWNT electrodes. The best supercapacitor cell of MWNT electrodes deposited on aluminium foil displayed good transverse orientation of the MWNT structures as well as an in-plane MWNT network at the feet of the protruding structures, which ensured good in-plane conductivity. Capacitor cells with MWNT electrodes deposited either on ITO-coated PET film or on PET film demonstrated lower but still very good performance due to the high density of transversely oriented MWNT structures (good transverse conductivity) but some in-plane inhomogeneities. Capacitor cells with drop-printed MWNTs on aluminium foil, without any transverse orientation, had 16-30 times lower specific capacitance and 5-40 times lower power density than the capacitor cells with the electrophoretically deposited MWNT electrodes.

Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells.

PubMed

Miyake, Junpei; Taki, Ryunosuke; Mochizuki, Takashi; Shimizu, Ryo; Akiyama, Ryo; Uchida, Makoto; Miyatake, Kenji

2017-10-01

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. Perfluorosulfonic acid (PFSA) ionomers (for example, Nafion) have been the benchmark PEMs; however, several problems, including high gas permeability, low thermal stability, high production cost, and environmental incompatibility, limit the widespread dissemination of PEMFCs. It is believed that fluorine-free PEMs can potentially address all of these issues; however, none of these membranes have simultaneously met the criteria for both high performance (for example, proton conductivity) and durability (for example, mechanical and chemical stability). We present a polyphenylene-based PEM (SPP-QP) that fulfills the required properties for fuel cell applications. The newly designed PEM exhibits very high proton conductivity, excellent membrane flexibility, low gas permeability, and extremely high stability, with negligible degradation even under accelerated degradation conditions, which has never been achieved with existing fluorine-free PEMs. The polyphenylene PEM also exhibits reasonably high fuel cell performance, with excellent durability under practical conditions. This new PEM extends the limits of existing fluorine-free proton-conductive materials and will help to realize the next generation of PEMFCs via cost reduction as well as the performance improvement compared to the present PFSA-based PEMFC systems.

High-performance non-enzymatic catalysts based on 3D hierarchical hollow porous Co3O4 nanododecahedras in situ decorated on carbon nanotubes for glucose detection and biofuel cell application.

PubMed

Wang, Shiyue; Zhang, Xiaohua; Huang, Junlin; Chen, Jinhua

2018-03-01

In this work, high-performance non-enzymatic catalysts based on 3D hierarchical hollow porous Co 3 O 4 nanododecahedras in situ decorated on carbon nanotubes (3D Co 3 O 4 -HPND/CNTs) were successfully prepared via direct carbonizing metal-organic framework-67 in situ grown on carbon nanotubes. The morphology, microstructure, and composite of 3D Co 3 O 4 -HPND/CNTs were characterized by scanning electron microscopy, transmission electron microscopy, micropore and chemisorption analyzer, and X-ray diffraction. The electrochemical characterizations indicated that 3D Co 3 O 4 -HPND/CNTs present considerably catalytic activity toward glucose oxidation and could be promising for constructing high-performance electrochemical non-enzymatic glucose sensors and glucose/O 2 biofuel cell. When used for non-enzymatic glucose detection, the 3D Co 3 O 4 -HPND/CNTs modified glassy carbon electrode (3D Co 3 O 4 -HPND/CNTs/GCE) exhibited excellent analytical performance with high sensitivity (22.21 mA mM -1  cm -2 ), low detection limit of 0.35 μM (S/N = 3), fast response (less than 5 s) and good stability. On the other hand, when the 3D Co 3 O 4 -HPND/CNTs/GCE worked as an anode of a biofuel cell, a maximum power density of 210 μW cm -2 at 0.15 V could be obtained, and the open circuit potential was 0.68 V. The attractive 3D hierarchical porous structural features, the large surface area, and the excellent conductivity based on the continuous and effective electron transport network in 3D Co 3 O 4 -HPND/CNTs endow 3D Co 3 O 4 -HPND/CNTs with the enhanced electrochemical performance and promising applications in electrochemical sensing, biofuel cell, and other energy storage and conversion devices such as supercapacitor. Graphical abstract High-performance non-enzymatic catalysts for enzymeless glucose sensing and biofuel cell based on 3D hierarchical hollow porous Co 3 O 4 nanododecahedras anchored on carbon nanotubes were successfully prepared via direct carbonizing metal-organic framework-67 in situ grown on carbon nanotubes.

Design of Low Inductance Switching Power Cell for GaN HEMT Based Inverter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurpinar, Emre; Iannuzzo, Francesco; Yang, Yongheng

Here in this paper, an ultra-low inductance power cell is designed for a three-Level Active Neutral Point Clamped (3LANPC) based on 650 V gallium nitride (GaN) HEMT devices. The 3L-ANPC topology with GaN HEMT devices and the selected modulation scheme suitable for wide-bandgap (WBG) devices are presented. The commutation loops, which mainly contribute to voltage overshoots and increase of switching losses, are discussed. The ultra-low inductance power cell design based on a fourlayer Printed Circuit Board (PCB) with the aim to maximize the switching performance of GaN HEMTs is explained. The design of gate drivers for the GaN HEMT devicesmore » is presented. Parasitic inductance and resistance of the proposed design are extracted with finite element analysis and discussed. Common mode behaviours based on the SPICE model of the converter are analyzed. Experimental results on the designed 3L-ANPC with the output power of up to 1 kW are presented, which verifies the performance of the proposed design in terms of ultra-low inductance.« less

Flexible feature-space-construction architecture and its VLSI implementation for multi-scale object detection

NASA Astrophysics Data System (ADS)

Luo, Aiwen; An, Fengwei; Zhang, Xiangyu; Chen, Lei; Huang, Zunkai; Jürgen Mattausch, Hans

2018-04-01

Feature extraction techniques are a cornerstone of object detection in computer-vision-based applications. The detection performance of vison-based detection systems is often degraded by, e.g., changes in the illumination intensity of the light source, foreground-background contrast variations or automatic gain control from the camera. In order to avoid such degradation effects, we present a block-based L1-norm-circuit architecture which is configurable for different image-cell sizes, cell-based feature descriptors and image resolutions according to customization parameters from the circuit input. The incorporated flexibility in both the image resolution and the cell size for multi-scale image pyramids leads to lower computational complexity and power consumption. Additionally, an object-detection prototype for performance evaluation in 65 nm CMOS implements the proposed L1-norm circuit together with a histogram of oriented gradients (HOG) descriptor and a support vector machine (SVM) classifier. The proposed parallel architecture with high hardware efficiency enables real-time processing, high detection robustness, small chip-core area as well as low power consumption for multi-scale object detection.

Applications of Photonic Crystals to Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Foster, Stephen

Photonic crystals are structures that exhibit wavelength-scale spatial periodicity in their dielectric function. They are best known for their ability to exhibit complete photonic band gaps (PBGs) - spectral regions over which no light can propagate within the crystal. PBGs are specific instances of a more general phenomenon, in which the local photonic density of states can be enhanced or suppressed over different frequency ranges by tuning the properties of the crystal. This can be used to redirect, concentrate, or even trap light incident on the crystal. In this thesis, we investigate how photonic crystals can be used to enhance the efficiency of photovoltaic devices by trapping light. Due to the many different types of photovoltaic devices in existence (varying widely in materials used, modes of operation, and internal structure), there is no single light trapping architecture that can be applied to all photovoltaics. In this work we study a number of different devices: dye-sensitized solar cells, polymer solar cells, silicon-perovskite tandem cells, and single-junction silicon cells. We propose novel photonic crystal-based light trapping designs for each type of device, and evaluate these designs numerically to demonstrate their effectiveness. Full-field optical simulations of the cell are performed for each design, using either finite element method (FEM) or finite-difference time-domain (FDTD) techniques. Where appropriate, electrical modelling of the cell is also performed, through either the use of a simple one-diode model, or by obtaining full solutions to the semiconductor drift-diffusion equations within the cell. In all cases we find that the photonic crystal-based designs significantly outperform their non-nanostructured counterparts. In the case of dye-sensitized and polymer cells, enhancements in light absorption of 33% and 40% (respectively) are seen, relative to reference cells with planar geometries. In the case of silicon-perovskite tandem cells and silicon cells, projected power conversion efficiencies of over 30% are obtained, well beyond the current world record for silicon-based cells. We conclude the thesis with a discussion on the overall prospects for photonic crystal-based solar cells, with a focus on the factors that make solar cell technologies amenable to light trapping.

Fast globally optimal segmentation of cells in fluorescence microscopy images.

PubMed

Bergeest, Jan-Philip; Rohr, Karl

2011-01-01

Accurate and efficient segmentation of cells in fluorescence microscopy images is of central importance for the quantification of protein expression in high-throughput screening applications. We propose a new approach for segmenting cell nuclei which is based on active contours and convex energy functionals. Compared to previous work, our approach determines the global solution. Thus, the approach does not suffer from local minima and the segmentation result does not depend on the initialization. We also suggest a numeric approach for efficiently computing the solution. The performance of our approach has been evaluated using fluorescence microscopy images of different cell types. We have also performed a quantitative comparison with previous segmentation approaches.

Multifunctional picoliter droplet manipulation platform and its application in single cell analysis.

PubMed

Gu, Shu-Qing; Zhang, Yun-Xia; Zhu, Ying; Du, Wen-Bin; Yao, Bo; Fang, Qun

2011-10-01

We developed an automated and multifunctional microfluidic platform based on DropLab to perform flexible generation and complex manipulations of picoliter-scale droplets. Multiple manipulations including precise droplet generation, sequential reagent merging, and multistep solid-phase extraction for picoliter-scale droplets could be achieved in the present platform. The system precision in generating picoliter-scale droplets was significantly improved by minimizing the thermo-induced fluctuation of flow rate. A novel droplet fusion technique based on the difference of droplet interfacial tensions was developed without the need of special microchannel networks or external devices. It enabled sequential addition of reagents to droplets on demand for multistep reactions. We also developed an effective picoliter-scale droplet splitting technique with magnetic actuation. The difficulty in phase separation of magnetic beads from picoliter-scale droplets due to the high interfacial tension was overcome using ferromagnetic particles to carry the magnetic beads to pass through the phase interface. With this technique, multistep solid-phase extraction was achieved among picoliter-scale droplets. The present platform had the ability to perform complex multistep manipulations to picoliter-scale droplets, which is particularly required for single cell analysis. Its utility and potentials in single cell analysis were preliminarily demonstrated in achieving high-efficiency single-cell encapsulation, enzyme activity assay at the single cell level, and especially, single cell DNA purification based on solid-phase extraction.

Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology.

PubMed

Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi

2015-12-03

This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm(2), and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p(+-)n homojunction through the formation of re-grown crystalline silicon layer (~5-10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method.

Micrometer-sized iron oxide particle labeling of mesenchymal stem cells for magnetic resonance imaging-based monitoring of cartilage tissue engineering.

PubMed

Saldanha, Karl J; Doan, Ryan P; Ainslie, Kristy M; Desai, Tejal A; Majumdar, Sharmila

2011-01-01

To examine mesenchymal stem cell (MSC) labeling with micrometer-sized iron oxide particles (MPIOs) for magnetic resonance imaging (MRI)-based tracking and its application to monitoring articular cartilage regeneration. Rabbit MSCs were labeled using commercial MPIOs. In vitro MRI was performed with gradient echo (GRE) and spin echo (SE) sequences at 3T and quantitatively characterized using line profile and region of interest analysis. Ex vivo MRI of hydrogel-encapsulated labeled MSCs implanted within a bovine knee was performed with spoiled GRE (SPGR) and T(1ρ) sequences. Fluorescence microscopy, labeling efficiency, and chondrogenesis of MPIO-labeled cells were also examined. MPIO labeling results in efficient contrast uptake and signal loss that can be visualized and quantitatively characterized via MRI. SPGR imaging of implanted cells results in ex vivo detection within native tissue, and T(1ρ) imaging is unaffected by the presence of labeled cells immediately following implantation. MPIO labeling does not affect quantitative glycosaminoglycan production during chondrogenesis, but iron aggregation hinders extracellular matrix visualization. This aggregation may result from excess unincorporated particles following labeling and is an issue that necessitates further investigation. This study demonstrates the promise of MPIO labeling for monitoring cartilage regeneration and highlights its potential in the development of cell-based tissue engineering strategies. Published by Elsevier Inc.

Progress in the Development of Oxygen Reduction Reaction Catalysts for Low-Temperature Fuel Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dongguo; Lv, Haifeng; Kang, Yijin

2016-04-06

In this paper, we present a brief summary on the most recent progress in the design of catalysts for electrochemical reduction of oxygen. The main challenge in the wide spread of fuel cell technology is to lower the content of, or even eliminate, Pt and other precious metals in catalysts without sacrificing their performance. Pt-based nanosized catalysts with novel and refined architectures continue to dominate in catalytic performance, and formation of Pt-skin-like surfaces is key to achieving the highest values in activity. Moreover, durability has also been improved in Pt-based systems with addition of Au, which plays an important rolemore » in stabilizing the Pt topmost layers against dissolution. However, various carbon-based materials without precious metal have shown improvement in activity and durability and have been explored to serve as catalyst supports. Finally, understanding how the doped elements interact with each other and/or carbon is challenging and necessary in the design of robust fuel cell catalysts.« less

Fine-Tuning the Quasi-3D Geometry: Enabling Efficient Nonfullerene Organic Solar Cells Based on Perylene Diimides.

PubMed

Liu, Zhitian; Zhang, Linhua; Shao, Ming; Wu, Yao; Zeng, Di; Cai, Xiang; Duan, Jiashun; Zhang, Xiaolu; Gao, Xiang

2018-01-10

The geometries of acceptors based on perylene diimides (PDIs) are important for improving the phase separation and charge transport in organic solar cells. To fine-tune the geometry, biphenyl, spiro-bifluorene, and benzene were used as the core moiety to construct quasi-three-dimensional nonfullerene acceptors based on PDI building blocks. The molecular geometries, energy levels, optical properties, photovoltaic properties, and exciton kinetics were systematically studied. The structure-performance relationship was discussed as well. Owing to the finest phase separation, the highest charge mobility and smallest nongeminate recombination, the power conversion efficiency of nonfullerene solar cells using PDI derivatives with biphenyl core (BP-PDI 4 ) as acceptor reached 7.3% when high-performance wide band gap donor material poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] was blended.

The optimum titanium precursor of fabricating TiO2 compact layer for perovskite solar cells.

PubMed

Qin, Jianqiang; Zhang, Zhenlong; Shi, Wenjia; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2017-12-29

Perovskite solar cells (PSCs) have attracted tremendous attentions due to its high performance and rapid efficiency promotion. Compact layer plays a crucial role in transferring electrons and blocking charge recombination between the perovskite layer and fluorine-doped tin oxide (FTO) in PSCs. In this study, compact TiO 2 layers were synthesized by spin-coating method with three different titanium precursors, titanium diisopropoxide bis (acetylacetonate) (c-TTDB), titanium isopropoxide (c-TTIP), and tetrabutyl titanate (c-TBOT), respectively. Compared with the PSCs based on the widely used c-TTDB and c-TTIP, the device based on c-TBOT has significantly enhanced performance, including open-circuit voltage, short-circuit current density, fill factor, and hysteresis. The significant enhancement is ascribed to its excellent morphology, high conductivity and optical properties, fast charge transfer, and large recombination resistance. Thus, a power conversion efficiency (PCE) of 17.03% has been achieved for the solar cells based on c-TBOT.

The optimum titanium precursor of fabricating TiO2 compact layer for perovskite solar cells

NASA Astrophysics Data System (ADS)

Qin, Jianqiang; Zhang, Zhenlong; Shi, Wenjia; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2017-12-01

Perovskite solar cells (PSCs) have attracted tremendous attentions due to its high performance and rapid efficiency promotion. Compact layer plays a crucial role in transferring electrons and blocking charge recombination between the perovskite layer and fluorine-doped tin oxide (FTO) in PSCs. In this study, compact TiO2 layers were synthesized by spin-coating method with three different titanium precursors, titanium diisopropoxide bis (acetylacetonate) (c-TTDB), titanium isopropoxide (c-TTIP), and tetrabutyl titanate (c-TBOT), respectively. Compared with the PSCs based on the widely used c-TTDB and c-TTIP, the device based on c-TBOT has significantly enhanced performance, including open-circuit voltage, short-circuit current density, fill factor, and hysteresis. The significant enhancement is ascribed to its excellent morphology, high conductivity and optical properties, fast charge transfer, and large recombination resistance. Thus, a power conversion efficiency (PCE) of 17.03% has been achieved for the solar cells based on c-TBOT.

Amorphous Hole-Transporting Material based on 2,2'-Bis-substituted 1,1'-Biphenyl Scaffold for Application in Perovskite Solar Cells.

PubMed

Magomedov, Artiom; Sakai, Nobuya; Kamarauskas, Egidijus; Jokubauskaitė, Gabrielė; Franckevičius, Marius; Jankauskas, Vygintas; Snaith, Henry J; Getautis, Vytautas

2017-05-04

Perovskite solar cells are considered a promising technology for solar-energy conversion, with power conversion efficiencies currently exceeding 20 %. In most of the reported devices, Spiro-OMeTAD is used for positive-charge extraction and transport layer. Although a number of alternative hole-transporting materials with different aromatic or heteroaromatic fragments have already been synthesized, a cheap and well-performing hole-transporting material is still in high demand. In this work, a two-step synthesis of a carbazole-based hole-transporting material is presented. Synthesized compounds exhibited amorphous nature, good solubility and thermal stability. The perovskite solar cells employing the newly synthesized material generated a power conversion efficiency of 16.5 % which is slightly lower than that obtained with Spiro-OMeTAD (17.5 %). The low-cost synthesis and high performance makes our hole-transport material promising for applications in perovskite-based optoelectronic devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rechargeable nickel-3D zinc batteries: An energy-dense, safer alternative to lithium-ion.

PubMed

Parker, Joseph F; Chervin, Christopher N; Pala, Irina R; Machler, Meinrad; Burz, Michael F; Long, Jeffrey W; Rolison, Debra R

2017-04-28

The next generation of high-performance batteries should include alternative chemistries that are inherently safer to operate than nonaqueous lithium-based batteries. Aqueous zinc-based batteries can answer that challenge because monolithic zinc sponge anodes can be cycled in nickel-zinc alkaline cells hundreds to thousands of times without undergoing passivation or macroscale dendrite formation. We demonstrate that the three-dimensional (3D) zinc form-factor elevates the performance of nickel-zinc alkaline cells in three fields of use: (i) >90% theoretical depth of discharge (DOD Zn ) in primary (single-use) cells, (ii) >100 high-rate cycles at 40% DOD Zn at lithium-ion-commensurate specific energy, and (iii) the tens of thousands of power-demanding duty cycles required for start-stop microhybrid vehicles. Copyright © 2017, American Association for the Advancement of Science.

The electrical power subsystem design for the high energy solar physics spacecraft concepts

NASA Technical Reports Server (NTRS)

Kulkarni, Milind

1993-01-01

This paper discusses the Electrical Power Subsystem (EPS) requirements, architecture, design description, performance analysis, and heritage of the components for two spacecraft concepts for the High Energy Solar Physics (HESP) Mission. It summarizes the mission requirements and the spacecraft subsystems and instrument power requirements, and it describes the EPS architecture for both options. A trade study performed on the selection of the solar cells - body mounted versus deployed panels - and the optimum number of panels is also presented. Solar cell manufacturing losses, array manufacturing losses, and the radiation and temperature effects on the GaAs/Ge and Si solar cells were considered part of the trade study and are included in this paper. Solar cell characteristics, cell circuit description, and the solar array area design are presented, as is battery sizing analysis performed based on the power requirements during launch and initial spacecraft operations. This paper discusses Earth occultation periods and the battery power requirements during this period as well as shunt control, battery conditioning, and bus regulation schemes. Design margins, redundancy philosophy, and predicted on-orbit battery and solar cell performance are summarized. Finally, the heritage of the components and technology risk assessment are provided.

Design issues for optimum solar cell configuration

NASA Astrophysics Data System (ADS)

Kumar, Atul; Thakur, Ajay D.

2018-05-01

A computer based simulation of solar cell structure is performed to study the optimization of pn junction configuration for photovoltaic action. The fundamental aspects of photovoltaic action viz, absorption, separation collection, and their dependence on material properties and deatails of device structures is discussed. Using SCAPS 1D we have simulated the ideal pn junction and shown the effect of band offset and carrier densities on solar cell performance. The optimum configuration can be achieved by optimizing transport of carriers in pn junction under effect of field dependent recombination (tunneling) and density dependent recombination (SRH, Auger) mechanisms.

Cathode limited charge transport and performance of thin-film rechargeable lithium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bates, J.B.; Hart, F.X.; Lubben, D.

1994-11-01

Several types of thin-film rechargeable batteries based on lithium metal anodes and amorphous V{sub 2}O{sub 5} (aV{sub 2}O{sub 5}), LiMn{sub 2}O{sub 4}, and LiCoO{sub 2} cathodes have been investigated in this laboratory. In all cases, the current density of these cells is limited by lithium ion transport in the cathodes. This paper, discusses sources of this impedance in Li-aV{sub 2}O{sub 5} and Li-LiMn{sub 2}O{sub 4} thin-film cells and their effect on cell performance.

High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

NASA Technical Reports Server (NTRS)

Bents, David J.

1987-01-01

A hydrogen-oxygen regenerative fuel cell energy storage system based on high temperature solid oxide fuel cell technology is discussed which has application to darkside energy storage for solar photovoltaics. The forward and reverse operating cycles are described, and heat flow, mass, and energy balance data are presented to characterize the system's performance and the variation of performance with changing reactant storage pressure. The present system weighs less than nickel hydrogen battery systems after 0.7 darkside operation, and it maintains a specific weight advantage over radioisotope generators for discharge periods up to 72 hours.

High temperature solid oxide regenerative fuel cell for solar photovoltaic energy storage

NASA Astrophysics Data System (ADS)

Bents, David J.

A hydrogen-oxygen regenerative fuel cell energy storage system based on high temperature solid oxide fuel cell technology is discussed which has application to darkside energy storage for solar photovoltaics. The forward and reverse operating cycles are described, and heat flow, mass, and energy balance data are presented to characterize the system's performance and the variation of performance with changing reactant storage pressure. The present system weighs less than nickel hydrogen battery systems after 0.7 darkside operation, and it maintains a specific weight advantage over radioisotope generators for discharge periods up to 72 hours.

Morphological tuning of polymeric nanoparticles via microfluidic platform for fuel cell applications.

PubMed

Hasani-Sadrabadi, Mohammad Mahdi; Majedi, Fatemeh Sadat; VanDersarl, Jules John; Dashtimoghadam, Erfan; Ghaffarian, S Reza; Bertsch, Arnaud; Moaddel, Homayoun; Renaud, Philippe

2012-11-21

At nanoscale length scales, the properties of particles change rapidly with the slightest change in dimension. The use of a microfluidic platform enables precise control of sub-100 nm organic nanoparticles (NPs) based on polybenzimidazole. Using hydrodynamic flow focusing, we can control the size and shape of the NPs, which in turn controls a number of particle material properties. The anhydrous proton-conducting nature of the prepared NPs allowed us to make a high-performance ion exchange membrane for fuel cell applications, and microfluidic tuning of the NPs allowed us subsequently to tune the fuel cell performance.

Phase-field modeling of liquids splitting between separating surfaces and its application to high-resolution roll-based printing technologies

NASA Astrophysics Data System (ADS)

Hizir, F. E.; Hardt, D. E.

2017-05-01

An in-depth understanding of the liquid transport in roll-based printing systems is essential for advancing the roll-based printing technology and enhancing the performance of the printed products. In this study, phase-field simulations are performed to characterize the liquid transport in roll-based printing systems, and the phase-field method is shown to be an effective tool to simulate the liquid transport. In the phase-field simulations, the liquid transport through the ink transfer rollers is approximated as the stretching and splitting of liquid bridges with pinned or moving contact lines between vertically separating surfaces. First, the effect of the phase-field parameters and the mesh characteristics on the simulation results is examined. The simulation results show that a sharp interface limit is approached as the capillary width decreases while keeping the mobility proportional to the capillary width squared. Close to the sharp interface limit, the mobility changes over a specified range are observed to have no significant influence on the simulation results. Next, the ink transfer from the cells on the surface of an ink-metering roller to the surface of stamp features is simulated. Under negligible inertial effects and in the absence of gravity, the amount of liquid ink transferred from an axisymmetric cell with low surface wettability to a stamp with high surface wettability is found to increase as the cell sidewall steepness and the cell surface wettability decrease and the stamp surface wettability and the capillary number increase. Strategies for improving the resolution and quality of roll-based printing are derived based on an analysis of the simulation results. The application of novel materials that contain cells with irregular surface topography to stamp inking in high-resolution roll-based printing is assessed.

Solvothermal Synthesis of Hierarchical TiO2 Microstructures with High Crystallinity and Superior Light Scattering for High-Performance Dye-Sensitized Solar Cells.

PubMed

Li, Zhao-Qian; Mo, Li-E; Chen, Wang-Chao; Shi, Xiao-Qiang; Wang, Ning; Hu, Lin-Hua; Hayat, Tasawar; Alsaedi, Ahmed; Dai, Song-Yuan

2017-09-20

In this article, hierarchical TiO 2 microstructures (HM-TiO 2 ) were synthesized by a simple solvothermal method adopting tetra-n-butyl titanate as the titanium source in a mixed solvent composed of N,N-dimethylformamide and acetic acid. Due to the high crystallinity and superior light-scattering ability, the resultant HM-TiO 2 are advantageous as photoanodes for dye-sensitized solar cells. When assembled to the entire photovoltaic device with C101 dye as a sensitizer, the pure HM-TiO 2 -based solar cells showed an ultrahigh photovoltage up to 0.853 V. Finally, by employing the as-obtained HM-TiO 2 as the scattering layer and optimizing the architecture of dye-sensitized solar cells, both higher photovoltage and incident photon-to-electron conversion efficiency value were harvested with respect to TiO 2 nanoparticles-based dye-sensitized solar cells, resulting in a high power conversion efficiency of 9.79%. This work provides a promising strategy to develop photoanode materials with outstanding photoelectric conversion performance.

Performance of intermediate temperature (600-800 °C) solid oxide fuel cell based on Sr and Mg doped lanthanum-gallate electrolyte

NASA Astrophysics Data System (ADS)

Gong, Wenquan; Gopalan, Srikanth; Pal, Uday B.

The solid electrolyte chosen for this investigation was La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSGM). To select appropriate electrode materials from a group of possible candidate materials, AC complex impedance spectroscopy studies were conducted between 600 and 800 °C on symmetrical cells that employed the LSGM electrolyte. Based on the results of the investigation, LSGM electrolyte supported solid oxide fuel cells (SOFCs) were fabricated with La 0.6Sr 0.4Co 0.8Fe 0.2O 3-La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSCF-LSGM) composite cathode and nickel-Ce 0.6La 0.4O 2 (Ni-LDC) composite anode having a barrier layer of Ce 0.6La 0.4O 2 (LDC) between the LSGM electrolyte and the Ni-LDC anode. Electrical performances of these cells were determined and the electrode polarization behavior as a function of cell current was modeled between 600 and 800 °C.

Simulation-based cheminformatic analysis of organelle-targeted molecules: lysosomotropic monobasic amines.

PubMed

Zhang, Xinyuan; Zheng, Nan; Rosania, Gus R

2008-09-01

Cell-based molecular transport simulations are being developed to facilitate exploratory cheminformatic analysis of virtual libraries of small drug-like molecules. For this purpose, mathematical models of single cells are built from equations capturing the transport of small molecules across membranes. In turn, physicochemical properties of small molecules can be used as input to simulate intracellular drug distribution, through time. Here, with mathematical equations and biological parameters adjusted so as to mimic a leukocyte in the blood, simulations were performed to analyze steady state, relative accumulation of small molecules in lysosomes, mitochondria, and cytosol of this target cell, in the presence of a homogenous extracellular drug concentration. Similarly, with equations and parameters set to mimic an intestinal epithelial cell, simulations were also performed to analyze steady state, relative distribution and transcellular permeability in this non-target cell, in the presence of an apical-to-basolateral concentration gradient. With a test set of ninety-nine monobasic amines gathered from the scientific literature, simulation results helped analyze relationships between the chemical diversity of these molecules and their intracellular distributions.

A Location-Based Duplex Scheme for Cost Effective Rural Broadband Connectivity Using IEEE 802.22 Cognitive Radio Based Wireless Regional Area Networks

NASA Astrophysics Data System (ADS)

Kalidoss, R.; Bhagyaveni, M. A.; Vishvaksenan, K. S.

2014-08-01

The search for a method of utilizing the scarce spectrum in an efficient manner is an active area of research in both academic and industrial communities. IEEE 802.22 is a standard for wireless regional area network (WRAN) based on cognitive radio (CR) that operates over underutilized portions of TV bands (54-862 MHz). Time division duplex (TDD)-based WRAN cells have such advantages as dynamic traffic allocation, traffic asymmetry to users and ease of spectrum allocation. However, these cells suffer from severe cross time slot (CTS) interference when the frames of the cells are not synchronized with adjacent WRAN cells. In this paper, we evaluate the location-based duplex (LBD) scheme for eliminating the CTS interference. The proposed LBD system is much more flexible and efficient in providing asymmetric data service and eliminating CTS interference by exploiting the advantages of both TDD and frequency division duplex (FDD) schemes. We also compare the performance of LBD systems with virtual cell concepts. Furthermore, our simulation results reveal that LBD-based systems outperform the virtual cell approach in terms of the low signal-to-interference (SIR) ratio requirement by mitigating the effects of CTS.

High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiency

NASA Astrophysics Data System (ADS)

Che, Xiaozhou; Li, Yongxi; Qu, Yue; Forrest, Stephen R.

2018-05-01

Multijunction solar cells are effective for increasing the power conversion efficiency beyond that of single-junction cells. Indeed, the highest solar cell efficiencies have been achieved using two or more subcells to adequately cover the solar spectrum. However, the efficiencies of organic multijunction solar cells are ultimately limited by the lack of high-performance, near-infrared absorbing organic subcells within the stack. Here, we demonstrate a tandem cell with an efficiency of 15.0 ± 0.3% (for 2 mm2 cells) that combines a solution-processed non-fullerene-acceptor-based infrared absorbing subcell on a visible-absorbing fullerene-based subcell grown by vacuum thermal evaporation. The hydrophilic-hydrophobic interface within the charge-recombination zone that connects the two subcells leads to >95% fabrication yield among more than 130 devices, and with areas up to 1 cm2. The ability to stack solution-based on vapour-deposited cells provides significant flexibility in design over the current, all-vapour-deposited multijunction structures.

NHS-based Tandem Mass Tagging of Proteins at the Level of Whole Cells: A Critical Evaluation in Comparison to Conventional TMT-Labeling Approaches for Quantitative Proteome Analysis.

PubMed

Megger, Dominik A; Pott, Leona L; Rosowski, Kristin; Zülch, Birgit; Tautges, Stephanie; Bracht, Thilo; Sitek, Barbara

2017-01-01

Tandem mass tags (TMT) are usually introduced at the levels of isolated proteins or peptides. Here, for the first time, we report the labeling of whole cells and a critical evaluation of its performance in comparison to conventional labeling approaches. The obtained results indicated that TMT protein labeling using intact cells is generally possible, if it is coupled to a subsequent enrichment using anti-TMT antibody. The quantitative results were similar to those obtained after labeling of isolated proteins and both were found to be slightly complementary to peptide labeling. Furthermore, when using NHS-based TMT, no specificity towards cell surface proteins was observed in the case of cell labeling. In summary, the conducted study revealed first evidence for the general possibility of TMT cell labeling and highlighted limitations of NHS-based labeling reagents. Future studies should therefore focus on the synthesis and investigation of membrane impermeable TMTs to increase specificity towards cell surface proteins.

Hydrophobic Organic Hole Transporters for Improved Moisture Resistance in Metal Halide Perovskite Solar Cells.

PubMed

Leijtens, Tomas; Giovenzana, Tommaso; Habisreutinger, Severin N; Tinkham, Jonathan S; Noel, Nakita K; Kamino, Brett A; Sadoughi, Golnaz; Sellinger, Alan; Snaith, Henry J

2016-03-09

Solar cells based on organic-inorganic perovskite semiconductor materials have recently made rapid improvements in performance, with the best cells performing at over 20% efficiency. With such rapid progress, questions such as cost and solar cell stability are becoming increasingly important to address if this new technology is to reach commercial deployment. The moisture sensitivity of commonly used organic-inorganic metal halide perovskites has especially raised concerns. Here, we demonstrate that the hygroscopic lithium salt commonly used as a dopant for the hole transport material in perovskite solar cells makes the top layer of the devices hydrophilic and causes the solar cells to rapidly degrade in the presence of moisture. By using novel, low cost, and hydrophobic hole transporters in conjunction with a doping method incorporating a preoxidized salt of the respective hole transporters, we are able to prepare efficient perovskite solar cells with greatly enhanced water resistance.

Round Trip Energy Efficiency of NASA Glenn Regenerative Fuel Cell System

NASA Technical Reports Server (NTRS)

Garcia, Christopher P.; Chang, Bei-jiann; Johnson, Donald W.; Bents, David J.; Scullin, Vincent J.; Jakupca, Ian J.; Scullin, Vincent J.; Jakupca, Ian J.

2006-01-01

NASA Glenn Research Center (GRC) has recently demonstrated a Polymer Electrolyte Membrane (PEM) based hydrogen/oxygen regenerative fuel cell system (RFCS) that operated for a charge/discharge cycle with round trip efficiency (RTE) greater than 50 percent. The regenerative fuel cell system (RFCS) demonstrated closed loop energy storage over a pressure range of 90 to 190 psig. In charge mode, a constant electrical power profile of 7.1 kWe was absorbed by the RFCS and stored as pressurized hydrogen and oxygen gas. In discharge mode, the system delivered 3 to 4 kWe of electrical power along with product water. Fuel cell and electrolyzer power profiles and polarization performance are documented in this paper. Individual cell performance and the variation of cell voltages within the electrochemical stacks are also reported. Fuel cell efficiency, electrolyzer efficiency, and the system RTE were calculated from the test data and are included below.

Implementation of a cone-beam backprojection algorithm on the cell broadband engine processor

NASA Astrophysics Data System (ADS)

Bockenbach, Olivier; Knaup, Michael; Kachelrieß, Marc

2007-03-01

Tomographic image reconstruction is computationally very demanding. In all cases the backprojection represents the performance bottleneck due to the high operational count and due to the high demand put on the memory subsystem. In the past, solving this problem has lead to the implementation of specific architectures, connecting Application Specific Integrated Circuits (ASICs) or Field Programmable Gate Arrays (FPGAs) to memory through dedicated high speed busses. More recently, there have also been attempt to use Graphic Processing Units (GPUs) to perform the backprojection step. Originally aimed at the gaming market, IBM, Toshiba and Sony have introduced the Cell Broadband Engine (CBE) processor, often considered as a multicomputer on a chip. Clocked at 3 GHz, the Cell allows for a theoretical performance of 192 GFlops and a peak data transfer rate over the internal bus of 200 GB/s. This performance indeed makes the Cell a very attractive architecture for implementing tomographic image reconstruction algorithms. In this study, we investigate the relative performance of a perspective backprojection algorithm when implemented on a standard PC and on the Cell processor. We compare these results to the performance achievable with FPGAs based boards and high end GPUs. The cone-beam backprojection performance was assessed by backprojecting a full circle scan of 512 projections of 1024x1024 pixels into a volume of size 512x512x512 voxels. It took 3.2 minutes on the PC (single CPU) and is as fast as 13.6 seconds on the Cell.

Effect of ethylene glycol doping on performance of PEDOT:PSS/µT-n-Si heterojunction solar cell

NASA Astrophysics Data System (ADS)

Singh, Prashant; Nakra, Rohan; Sivaiah, B.; Sardana, Sanjay K.; Prathap, P.; Rauthan, C. M. S.; Srivastava, Sanjay K.

2018-05-01

This study reports effect of co-solvent doping in poly (3, 4-ethyelenedioxythiophene):poly(dimethyl sulfoxide) (PEDOT:PSS) over the performance of Ag/PEDOT:PSS/µT-n-Si/In:Ga architecture based solar cell. PEDOT:PSS polymer is doped with varying concentration of ethylene glycol (EG). At 10% (volume) concentration performance of the device is highest with 4.69% power conversion efficiency. At higher or lower concentrations of ethylene glycol device performance deteriorates with sharp decline in short-circuit current density. Improvement in conductivity of the PEDOT:PSS polymer due to addition of co-solvent is the reason behind improvement in the performance of the device efficiency.

Single-Cell Whole-Genome Amplification and Sequencing: Methodology and Applications.

PubMed

Huang, Lei; Ma, Fei; Chapman, Alec; Lu, Sijia; Xie, Xiaoliang Sunney

2015-01-01

We present a survey of single-cell whole-genome amplification (WGA) methods, including degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR), multiple displacement amplification (MDA), and multiple annealing and looping-based amplification cycles (MALBAC). The key parameters to characterize the performance of these methods are defined, including genome coverage, uniformity, reproducibility, unmappable rates, chimera rates, allele dropout rates, false positive rates for calling single-nucleotide variations, and ability to call copy-number variations. Using these parameters, we compare five commercial WGA kits by performing deep sequencing of multiple single cells. We also discuss several major applications of single-cell genomics, including studies of whole-genome de novo mutation rates, the early evolution of cancer genomes, circulating tumor cells (CTCs), meiotic recombination of germ cells, preimplantation genetic diagnosis (PGD), and preimplantation genomic screening (PGS) for in vitro-fertilized embryos.

Dithienogermole as a fused electron donor in bulk heterojunction solar cells.

PubMed

Amb, Chad M; Chen, Song; Graham, Kenneth R; Subbiah, Jegadesan; Small, Cephas E; So, Franky; Reynolds, John R

2011-07-06

We report the synthesis and bulk heterojunction photovoltaic performance of the first dithienogermole (DTG)-containing conjugated polymer. Stille polycondensation of a distannyl-DTG derivative with 1,3-dibromo-N-octyl-thienopyrrolodione (TPD) results in an alternating copolymer which displays light absorption extending to 735 nm, and a higher HOMO level than the analogous copolymer containing the commonly utilized dithienosilole (DTS) heterocycle. When polyDTG-TPD:PC(70)BM blends are utilized in inverted bulk heterojunction solar cells, the cells display average power conversion efficiencies of 7.3%, compared to 6.6% for the DTS-containing cells prepared in parallel under identical conditions. The performance enhancement is a result of a higher short-circuit current and fill factor in the DTG-containing cells, which comes at the cost of a slightly lower open circuit voltage than for the DTS-based cells.

Combinatorial electrochemical cell array for high throughput screening of micro-fuel-cells and metal/air batteries.

PubMed

Jiang, Rongzhong

2007-07-01

An electrochemical cell array was designed that contains a common air electrode and 16 microanodes for high throughput screening of both fuel cells (based on polymer electrolyte membrane) and metal/air batteries (based on liquid electrolyte). Electrode materials can easily be coated on the anodes of the electrochemical cell array and screened by switching a graphite probe from one cell to the others. The electrochemical cell array was used to study direct methanol fuel cells (DMFCs), including high throughput screening of electrode catalysts and determination of optimum operating conditions. For screening of DMFCs, there is about 6% relative standard deviation (percentage of standard deviation versus mean value) for discharge current from 10 to 20 mAcm(2). The electrochemical cell array was also used to study tin/air batteries. The effect of Cu content in the anode electrode on the discharge performance of the tin/air battery was investigated. The relative standard deviations for screening of metal/air battery (based on zinc/air) are 2.4%, 3.6%, and 5.1% for discharge current at 50, 100, and 150 mAcm(2), respectively.

Sensing in tissue bioreactors

NASA Astrophysics Data System (ADS)

Rolfe, P.

2006-03-01

Specialized sensing and measurement instruments are under development to aid the controlled culture of cells in bioreactors for the fabrication of biological tissues. Precisely defined physical and chemical conditions are needed for the correct culture of the many cell-tissue types now being studied, including chondrocytes (cartilage), vascular endothelial cells and smooth muscle cells (blood vessels), fibroblasts, hepatocytes (liver) and receptor neurones. Cell and tissue culture processes are dynamic and therefore, optimal control requires monitoring of the key process variables. Chemical and physical sensing is approached in this paper with the aim of enabling automatic optimal control, based on classical cell growth models, to be achieved. Non-invasive sensing is performed via the bioreactor wall, invasive sensing with probes placed inside the cell culture chamber and indirect monitoring using analysis within a shunt or a sampling chamber. Electroanalytical and photonics-based systems are described. Chemical sensing for gases, ions, metabolites, certain hormones and proteins, is under development. Spectroscopic analysis of the culture medium is used for measurement of glucose and for proteins that are markers of cell biosynthetic behaviour. Optical interrogation of cells and tissues is also investigated for structural analysis based on scatter.

Using pre-distorted PAM-4 signal and parallel resistance circuit to enhance the passive solar cell based visible light communication

NASA Astrophysics Data System (ADS)

Wang, Hao-Yu; Wu, Jhao-Ting; Chow, Chi-Wai; Liu, Yang; Yeh, Chien-Hung; Liao, Xin-Lan; Lin, Kun-Hsien; Wu, Wei-Liang; Chen, Yi-Yuan

2018-01-01

Using solar cell (or photovoltaic cell) for visible light communication (VLC) is attractive. Apart from acting as a VLC receiver (Rx), the solar cell can provide energy harvesting. This can be used in self-powered smart devices, particularly in the emerging ;Internet of Things (IoT); networks. Here, we propose and demonstrate for the first time using pre-distortion pulse-amplitude-modulation (PAM)-4 signal and parallel resistance circuit to enhance the transmission performance of solar cell Rx based VLC. Pre-distortion is a simple non-adaptive equalization technique that can significantly mitigate the slow charging and discharging of the solar cell. The equivalent circuit model of the solar cell and the operation of using parallel resistance to increase the bandwidth of the solar cell are discussed. By using the proposed schemes, the experimental results show that the data rate of the solar cell Rx based VLC can increase from 20 kbit/s to 1.25 Mbit/s (about 60 times) with the bit error-rate (BER) satisfying the 7% forward error correction (FEC) limit.

Online energy management strategy of fuel cell hybrid electric vehicles based on data fusion approach

NASA Astrophysics Data System (ADS)

Zhou, Daming; Al-Durra, Ahmed; Gao, Fei; Ravey, Alexandre; Matraji, Imad; Godoy Simões, Marcelo

2017-10-01

Energy management strategy plays a key role for Fuel Cell Hybrid Electric Vehicles (FCHEVs), it directly affects the efficiency and performance of energy storages in FCHEVs. For example, by using a suitable energy distribution controller, the fuel cell system can be maintained in a high efficiency region and thus saving hydrogen consumption. In this paper, an energy management strategy for online driving cycles is proposed based on a combination of the parameters from three offline optimized fuzzy logic controllers using data fusion approach. The fuzzy logic controllers are respectively optimized for three typical driving scenarios: highway, suburban and city in offline. To classify patterns of online driving cycles, a Probabilistic Support Vector Machine (PSVM) is used to provide probabilistic classification results. Based on the classification results of the online driving cycle, the parameters of each offline optimized fuzzy logic controllers are then fused using Dempster-Shafer (DS) evidence theory, in order to calculate the final parameters for the online fuzzy logic controller. Three experimental validations using Hardware-In-the-Loop (HIL) platform with different-sized FCHEVs have been performed. Experimental comparison results show that, the proposed PSVM-DS based online controller can achieve a relatively stable operation and a higher efficiency of fuel cell system in real driving cycles.

384 hanging drop arrays give excellent Z-factors and allow versatile formation of co-culture spheroids.

PubMed

Hsiao, Amy Y; Tung, Yi-Chung; Qu, Xianggui; Patel, Lalit R; Pienta, Kenneth J; Takayama, Shuichi

2012-05-01

We previously reported the development of a simple, user-friendly, and versatile 384 hanging drop array plate for 3D spheroid culture and the importance of utilizing 3D cellular models in anti-cancer drug sensitivity testing. The 384 hanging drop array plate allows for high-throughput capabilities and offers significant improvements over existing 3D spheroid culture methods. To allow for practical 3D cell-based high-throughput screening and enable broader use of the plate, we characterize the robustness of the 384 hanging drop array plate in terms of assay performance and demonstrate the versatility of the plate. We find that the 384 hanging drop array plate performance is robust in fluorescence- and colorimetric-based assays through Z-factor calculations. Finally, we demonstrate different plate capabilities and applications, including: spheroid transfer and retrieval for Janus spheroid formation, sequential addition of cells for concentric layer patterning of different cell types, and culture of a wide variety of cell types. Copyright © 2011 Wiley Periodicals, Inc.

384 Hanging Drop Arrays Give Excellent Z-factors and Allow Versatile Formation of Co-culture Spheroids

PubMed Central

Hsiao, Amy Y.; Tung, Yi-Chung; Qu, Xianggui; Patel, Lalit R.; Pienta, Kenneth J.; Takayama, Shuichi

2012-01-01

We previously reported the development of a simple, user-friendly, and versatile 384 hanging drop array plate for 3D spheroid culture and the importance of utilizing 3D cellular models in anti-cancer drug sensitivity testing. The 384 hanging drop array plate allows for high-throughput capabilities and offers significant improvements over existing 3D spheroid culture methods. To allow for practical 3D cell-based high-throughput screening and enable broader use of the plate, we characterize the robustness of the 384 hanging drop array plate in terms of assay performance and demonstrate the versatility of the plate. We find that the 384 hanging drop array plate performance is robust in fluorescence- and colorimetric-based assays through z-factor calculations. Finally, we demonstrate different plate capabilities and applications, including: spheroid transfer and retrieval for Janus spheroid formation, sequential addition of cells for concentric layer patterning of different cell types, and culture of a wide variety of cell types. PMID:22161651

A Blueprint for a Synthetic Genetic Feedback Controller to Reprogram Cell Fate.

PubMed

Del Vecchio, Domitilla; Abdallah, Hussein; Qian, Yili; Collins, James J

2017-01-25

To artificially reprogram cell fate, experimentalists manipulate the gene regulatory networks (GRNs) that maintain a cell's phenotype. In practice, reprogramming is often performed by constant overexpression of specific transcription factors (TFs). This process can be unreliable and inefficient. Here, we address this problem by introducing a new approach to reprogramming based on mathematical analysis. We demonstrate that reprogramming GRNs using constant overexpression may not succeed in general. Instead, we propose an alternative reprogramming strategy: a synthetic genetic feedback controller that dynamically steers the concentration of a GRN's key TFs to any desired value. The controller works by adjusting TF expression based on the discrepancy between desired and actual TF concentrations. Theory predicts that this reprogramming strategy is guaranteed to succeed, and its performance is independent of the GRN's structure and parameters, provided that feedback gain is sufficiently high. As a case study, we apply the controller to a model of induced pluripotency in stem cells. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Machine Learning Based Single-Frame Super-Resolution Processing for Lensless Blood Cell Counting

PubMed Central

Huang, Xiwei; Jiang, Yu; Liu, Xu; Xu, Hang; Han, Zhi; Rong, Hailong; Yang, Haiping; Yan, Mei; Yu, Hao

2016-01-01

A lensless blood cell counting system integrating microfluidic channel and a complementary metal oxide semiconductor (CMOS) image sensor is a promising technique to miniaturize the conventional optical lens based imaging system for point-of-care testing (POCT). However, such a system has limited resolution, making it imperative to improve resolution from the system-level using super-resolution (SR) processing. Yet, how to improve resolution towards better cell detection and recognition with low cost of processing resources and without degrading system throughput is still a challenge. In this article, two machine learning based single-frame SR processing types are proposed and compared for lensless blood cell counting, namely the Extreme Learning Machine based SR (ELMSR) and Convolutional Neural Network based SR (CNNSR). Moreover, lensless blood cell counting prototypes using commercial CMOS image sensors and custom designed backside-illuminated CMOS image sensors are demonstrated with ELMSR and CNNSR. When one captured low-resolution lensless cell image is input, an improved high-resolution cell image will be output. The experimental results show that the cell resolution is improved by 4×, and CNNSR has 9.5% improvement over the ELMSR on resolution enhancing performance. The cell counting results also match well with a commercial flow cytometer. Such ELMSR and CNNSR therefore have the potential for efficient resolution improvement in lensless blood cell counting systems towards POCT applications. PMID:27827837

MicroRNA Gene Regulatory Networks in Peripheral Nerve Sheath Tumors

DTIC Science & Technology

2012-09-01

chondrosarcoma are identified based on the unique histology, cell of origin, clinical features and site distribution. The following are the major... Chondrosarcoma Chondrosarcoma is a cancer composed of cells derived from transformed cells that produce cartilage. Peripheral chondrosarcoma is a malignant...biosynthesis. This is in line with gene expression analyses previously performed in osteochondroma and chondrosarcoma samples showing modulation of

High efficiency, long life terrestrial solar panel

NASA Technical Reports Server (NTRS)

Chao, T.; Khemthong, S.; Ling, R.; Olah, S.

1977-01-01

The design of a high efficiency, long life terrestrial module was completed. It utilized 256 rectangular, high efficiency solar cells to achieve high packing density and electrical output. Tooling for the fabrication of solar cells was in house and evaluation of the cell performance was begun. Based on the power output analysis, the goal of a 13% efficiency module was achievable.

Materials, device, and interface engineering to improve polymer-based solar cells

NASA Astrophysics Data System (ADS)

Hau, Steven Kin

The continued depletion of fossil fuel resources has lead to the rise in energy production costs which has lead to the search for an economically viable alternative energy source. One alternative of particular interest is solar energy. A promising alternative to inorganic materials is organic semiconductor polymer solar cells due to their advantages of being cheaper, light weight, flexible and made into large areas by roll-to-roll processing. In this dissertation, an integrated approach is taken to improve the overall performance of polymer-based solar cells by the development of new polymer materials, device architectures, and interface engineering of the contacts between layers. First, a new class of metallated conjugated polymers is explored as potential solar cell materials. Systematic modifications to the molecular units on the main chain of amorphous metallated Pt-polymers show a correlation that improving charge carrier mobility also improves solar cell performance leading to mobilities as high as 1 x 10-2 cm2/V·s and efficiencies as high as 4.1%. Second, an inverted device architecture using a more air stable electrode (Ag) is demonstrated to improve the ambient stability of unencapsulated P3HT:PCBM devices showing over 80% efficiency retention after 40 days of exposure. To further demonstrate the potential for roll-to-roll processing of polymer solar cells, solution processed Ag-nanoparticles were used to replace the vacuum deposited Ag anode electrode for inverted solar cells showing efficiencies as high as 3%. In addition, solution processed polymer based electrodes were demonstrated as a replacement to the expensive and brittle indium tin oxide showing efficiencies of 3% on flexible substrate solar cells. Third, interface engineering of the n-type (high temperature sol-gel processed TiO2 or ZnO, low temperature processed ZnO nanoparticles) electron selective metal oxide contacts in inverted solar cells with self-assembled monolayers (SAM) show improved device performance. Modifying the n-type layer in inverted cells with C60-SAMs containing different anchoring groups leads to an improvement in photocurrent density and fill factor leading to efficiencies as high as 4.9%.

Performance analysis of high-concentrated multi-junction solar cells in hot climate

NASA Astrophysics Data System (ADS)

Ghoneim, Adel A.; Kandil, Kandil M.; Alzanki, Talal H.; Alenezi, Mohammad R.

2018-03-01

Multi-junction concentrator solar cells are a promising technology as they can fulfill the increasing energy demand with renewable sources. Focusing sunlight upon the aperture of multi-junction photovoltaic (PV) cells can generate much greater power densities than conventional PV cells. So, concentrated PV multi-junction solar cells offer a promising way towards achieving minimum cost per kilowatt-hour. However, these cells have many aspects that must be fixed to be feasible for large-scale energy generation. In this work, a model is developed to analyze the impact of various atmospheric factors on concentrator PV performance. A single-diode equivalent circuit model is developed to examine multi-junction cells performance in hot weather conditions, considering the impacts of both temperature and concentration ratio. The impacts of spectral variations of irradiance on annual performance of various high-concentrated photovoltaic (HCPV) panels are examined, adapting spectra simulations using the SMARTS model. Also, the diode shunt resistance neglected in the existing models is considered in the present model. The present results are efficiently validated against measurements from published data to within 2% accuracy. Present predictions show that the single-diode model considering the shunt resistance gives accurate and reliable results. Also, aerosol optical depth (AOD) and air mass are most important atmospheric parameters having a significant impact on HCPV cell performance. In addition, the electrical efficiency (η) is noticed to increase with concentration to a certain concentration degree after which it decreases. Finally, based on the model predictions, let us conclude that the present model could be adapted properly to examine HCPV cells' performance over a broad range of operating conditions.

Bags versus flasks: a comparison of cell culture systems for the production of dendritic cell-based immunotherapies.

PubMed

Fekete, Natalie; Béland, Ariane V; Campbell, Katie; Clark, Sarah L; Hoesli, Corinne A

2018-04-19

In recent years, cell-based therapies targeting the immune system have emerged as promising strategies for cancer treatment. This review summarizes manufacturing challenges related to production of antigen presenting cells as a patient-tailored cancer therapy. Understanding cell-material interactions is essential because in vitro cell culture manipulations to obtain mature antigen-producing cells can significantly alter their in vivo performance. Traditional antigen-producing cell culture protocols often rely on cell adhesion to surface-treated hydrophilic polystyrene flasks. More recent commercial and investigational cancer immunotherapy products were manufactured using suspension cell culture in closed hydrophobic fluoropolymer bags. The shift to closed cell culture systems can decrease risks of contamination by individual operators, as well as facilitate scale-up and automation. Selecting closed cell culture bags over traditional open culture systems entails different handling procedures and processing controls, which can affect product quality. Changes in culture vessels also entail changes in vessel materials and geometry, which may alter the cell microenvironment and resulting cell fate decisions. Strategically designed culture systems will pave the way for the generation of more sophisticated and highly potent cell-based cancer vaccines. As an increasing number of cell-based therapies enter the clinic, the selection of appropriate cell culture vessels and materials becomes a critical consideration that can impact the therapeutic efficacy of the product, and hence clinical outcomes and patient quality of life. © 2018 The Authors Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.

A dynamic plug flow reactor model for a vanadium redox flow battery cell

NASA Astrophysics Data System (ADS)

Li, Yifeng; Skyllas-Kazacos, Maria; Bao, Jie

2016-04-01

A dynamic plug flow reactor model for a single cell VRB system is developed based on material balance, and the Nernst equation is employed to calculate cell voltage with consideration of activation and concentration overpotentials. Simulation studies were conducted under various conditions to investigate the effects of several key operation variables including electrolyte flow rate, upper SOC limit and input current magnitude on the cell charging performance. The results show that all three variables have a great impact on performance, particularly on the possibility of gassing during charging at high SOCs or inadequate flow rates. Simulations were also carried out to study the effects of electrolyte imbalance during long term charging and discharging cycling. The results show the minimum electrolyte flow rate needed for operation within a particular SOC range in order to avoid gassing side reactions during charging. The model also allows scheduling of partial electrolyte remixing operations to restore capacity and also avoid possible gassing side reactions during charging. Simulation results also suggest the proper placement for cell voltage monitoring and highlight potential problems associated with setting the upper charging cut-off limit based on the inlet SOC calculated from the open-circuit cell voltage measurement.

Silicon micro-fabricated miniature polymer electrolyte fuel cells

NASA Astrophysics Data System (ADS)

Kelley, Shawn Christopher

2000-10-01

The present thesis relates the design, fabrication, and testing of a unique type of silicon-based, miniature fuel cell. The fuel cell electrodes were constructed using standard silicon micro-fabrication techniques, and were used to construct miniature polymer electrolyte fuel cells (PEFCs) using NafionRTM. During testing, methanol and oxygen were the common reactants, but hydrogen and oxygen could be used as well. A novel form of an electrodeposited Pt:Ru alloy was developed for use as a methanol electrooxidation catalyst in the mini-PEFCs. An optimized mini-PEFC design was developed, tested, and compared with large PEFCs on the basis of performance. Mini-PEFC performance was equivalent to that of large PEFCs when scaled for active-area, but was limited by the function of the oxygen electrode. The rate of methanol crossover in a methanol/oxygen mini-PEFC was predicted using Fick's first law and the electrode chip feed-hole area. It was shown that the present mini-PEFC design could function as a fuel cell material test structure. Additionally, the mini-PEFCs were tested as two-cell stacks and as methanol sensors. The miniature, silicon-based PEFCs developed here successfully incorporate the essential aspects of a large PEFC in a smaller, simpler design.

Assessment and comparison of 100-MW coal gasification phosphoric acid fuel cell power plants

NASA Technical Reports Server (NTRS)

Lu, Cheng-Yi

1988-01-01

One of the advantages of fuel cell (FC) power plants is fuel versatility. With changes only in the fuel processor, the power plant will be able to accept a variety of fuels. This study was performed to design process diagrams, evaluate performance, and to estimate cost of 100 MW coal gasifier (CG)/phosphoric acid fuel cell (PAFC) power plant systems utilizing coal, which is the largest single potential source of alternate hydrocarbon liquids and gases in the United States, as the fuel. Results of this study will identify the most promising integrated CG/PAFC design and its near-optimal operating conditions. The comparison is based on the performance and cost of electricity which is calculated under consistent financial assumptions.

Halotolerant extremophile bacteria from the Great Salt Lake for recycling pollutants in microbial fuel cells

NASA Astrophysics Data System (ADS)

Grattieri, Matteo; Suvira, Milomir; Hasan, Kamrul; Minteer, Shelley D.

2017-07-01

The treatment of hypersaline wastewater (approximately 5% of the wastewater worldwide) cannot be performed by classical biological techniques. Herein the halotolerant extremophile bacteria obtained from the Great Salt Lake (Utah) were explored in single chamber microbial fuel cells with Pt-free cathodes for more than 18 days. The bacteria samples collected in two different locations of the lake (Stansbury Bay and Antelope Island) showed different electrochemical performances. The maximum achieved power output of 36 mW m-2 was from the microbial fuel cell based on the sample originated from Stansbury Bay, at a current density of 820 mA m-2. The performances throughout the long-term operation are discussed and a bioelectrochemical mechanism is proposed.

High Temperature Steam Electrolysis: Demonstration of Improved Long-Term Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. E. O'Brien; X. Zhang; R. C. O'Brien

2011-11-01

Long-term performance is an ongoing issue for hydrogen production based on high-temperature steam electrolysis (HTSE). For commercial deployment, solid-oxide electrolysis stacks must achieve high performance with long-term degradation rates of {approx}0.5%/1000 hours or lower. Significant progress has been achieved toward this goal over the past few years. This paper will provide details of progress achieved under the Idaho National Laboratory high temperature electrolysis research program. Recent long-term stack tests have achieved high initial performance with degradation rates less than 5%/khr. These tests utilize internally manifolded stacks with electrode-supported cells. The cell material sets are optimized for the electrolysis mode ofmore » operation. Details of the cells and stacks will be provided along with details of the test apparatus, procedures, and results.« less

Integrated microfluidic devices for combinatorial cell-based assays.

PubMed

Yu, Zeta Tak For; Kamei, Ken-ichiro; Takahashi, Hiroko; Shu, Chengyi Jenny; Wang, Xiaopu; He, George Wenfu; Silverman, Robert; Radu, Caius G; Witte, Owen N; Lee, Ki-Bum; Tseng, Hsian-Rong

2009-06-01

The development of miniaturized cell culture platforms for performing parallel cultures and combinatorial assays is important in cell biology from the single-cell level to the system level. In this paper we developed an integrated microfluidic cell-culture platform, Cell-microChip (Cell-microChip), for parallel analyses of the effects of microenvironmental cues (i.e., culture scaffolds) on different mammalian cells and their cellular responses to external stimuli. As a model study, we demonstrated the ability of culturing and assaying several mammalian cells, such as NIH 3T3 fibroblast, B16 melanoma and HeLa cell lines, in a parallel way. For functional assays, first we tested drug-induced apoptotic responses from different cell lines. As a second functional assay, we performed "on-chip" transfection of a reporter gene encoding an enhanced green fluorescent protein (EGFP) followed by live-cell imaging of transcriptional activation of cyclooxygenase 2 (Cox-2) expression. Collectively, our Cell-microChip approach demonstrated the capability to carry out parallel operations and the potential to further integrate advanced functions and applications in the broader space of combinatorial chemistry and biology.

Integrated microfluidic devices for combinatorial cell-based assays

PubMed Central

Yu, Zeta Tak For; Kamei, Ken-ichiro; Takahashi, Hiroko; Shu, Chengyi Jenny; Wang, Xiaopu; He, George Wenfu; Silverman, Robert

2010-01-01

The development of miniaturized cell culture platforms for performing parallel cultures and combinatorial assays is important in cell biology from the single-cell level to the system level. In this paper we developed an integrated microfluidic cell-culture platform, Cell-microChip (Cell-μChip), for parallel analyses of the effects of microenvir-onmental cues (i.e., culture scaffolds) on different mammalian cells and their cellular responses to external stimuli. As a model study, we demonstrated the ability of culturing and assaying several mammalian cells, such as NIH 3T3 fibro-blast, B16 melanoma and HeLa cell lines, in a parallel way. For functional assays, first we tested drug-induced apoptotic responses from different cell lines. As a second functional assay, we performed "on-chip" transfection of a reporter gene encoding an enhanced green fluorescent protein (EGFP) followed by live-cell imaging of transcriptional activation of cyclooxygenase 2 (Cox-2) expression. Collectively, our Cell-μChip approach demonstrated the capability to carry out parallel operations and the potential to further integrate advanced functions and applications in the broader space of combinatorial chemistry and biology. PMID:19130244

Enhancement of Performance and Mechanism Studies of All-Solution Processed Small-Molecule based Solar Cells with an Inverted Structure.

PubMed

Long, Guankui; Wu, Bo; Yang, Xuan; Kan, Bin; Zhou, Ye-Cheng; Chen, Li-Chuan; Wan, Xiangjian; Zhang, Hao-Li; Sum, Tze Chien; Chen, Yongsheng

2015-09-30

Both solution-processed polymers and small molecule based solar cells have achieved PCEs over 9% with the conventional device structure. However, for the practical applications of photovoltaic technology, further enhancement of both device performance and stability are urgently required, particularly for the inverted structure devices, since this architecture will probably be most promising for the possible coming commercialization. In this work, we have fabricated both conventional and inverted structure devices using the same small molecular donor/acceptor materials and compared the performance of both device structures, and found that the inverted structure based device gave significantly improved performance, the highest PCE so far for inverted structure based device using small molecules as the donor. Furthermore, the inverted device shows a remarkable stability with almost no obvious degradation after three months. Systematic device physics and charge generation dynamics studies, including optical simulation, light-intensity-dependent current-voltage experiments, photocurrent density-effective voltage analyses, transient absorption measurements, and electrical simulations, indicate that the significantly enhanced performance using inverted device is ascribed to the increasing of Jsc compared to the conventional device, which in turn is mainly attributed to the increased absorption of photons in the active layers, rather than the reduced nongeminate recombination.

Correlation between CdSe QD Synthesis, Post-Synthetic Treatment, and BHJ Hybrid Solar Cell Performance

PubMed Central

Eck, Michael; Krueger, Michael

2016-01-01

In this publication we show that the procedure to synthesize nanocrystals and the post-synthetic nanocrystal ligand sphere treatment have a great influence not only on the immediate performance of hybrid bulk heterojunction solar cells, but also on their thermal, long-term, and air stability. We herein demonstrate this for the particular case of spherical CdSe nanocrystals, post-synthetically treated with a hexanoic acid based treatment. We observe an influence from the duration of this post-synthetic treatment on the nanocrystal ligand sphere size, and also on the solar cell performance. By tuning the post-synthetic treatment to a certain degree, optimal device performance can be achieved. Moreover, we show how to effectively adapt the post-synthetic nanocrystal treatment protocol to different nanocrystal synthesis batches, hence increasing the reproducibility of hybrid nanocrystal:polymer bulk-heterojunction solar cells, which usually suffers due to the fluctuations in nanocrystal quality of different synthesis batches and synthesis procedures. PMID:28335243

Iridium-Based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alia, Shaun M.; Shulda, Sarah; Ngo, Chilan

Iridium-nickel (Ir-Ni) and iridium-cobalt (Ir-Co) nanowires have been synthesized by galvanic displacement and studied for their potential to increase the performance and durability of electrolysis systems. Performances of Ir-Ni and Ir-Co nanowires for the oxygen evolution reaction (OER) have been measured in rotating disk electrode half-cells and single-cell electrolyzers and compared with commercial baselines and literature references. The nanowire catalysts showed improved mass activity, by more than an order of magnitude compared with commercial Ir nanoparticles in half-cell tests. The nanowire catalysts also showed greatly improved durability, when acid-leached to remove excess Ni and Co. Both Ni and Co templatesmore » were found to have similarly positive impacts, although specific differences between the two systems are revealed. In single-cell electrolysis testing, nanowires exceeded the performance of Ir nanoparticles by 4-5 times, suggesting that significant reductions in catalyst loading are possible without compromising performance.« less

Iridium-Based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts

DOE PAGES

Alia, Shaun M.; Shulda, Sarah; Ngo, Chilan; ...

2018-01-22

Iridium-nickel (Ir-Ni) and iridium-cobalt (Ir-Co) nanowires have been synthesized by galvanic displacement and studied for their potential to increase the performance and durability of electrolysis systems. Performances of Ir-Ni and Ir-Co nanowires for the oxygen evolution reaction (OER) have been measured in rotating disk electrode half-cells and single-cell electrolyzers and compared with commercial baselines and literature references. The nanowire catalysts showed improved mass activity, by more than an order of magnitude compared with commercial Ir nanoparticles in half-cell tests. The nanowire catalysts also showed greatly improved durability, when acid-leached to remove excess Ni and Co. Both Ni and Co templatesmore » were found to have similarly positive impacts, although specific differences between the two systems are revealed. In single-cell electrolysis testing, nanowires exceeded the performance of Ir nanoparticles by 4-5 times, suggesting that significant reductions in catalyst loading are possible without compromising performance.« less

Standard cell-based implementation of a digital optoelectronic neural-network hardware.

PubMed

Maier, K D; Beckstein, C; Blickhan, R; Erhard, W

2001-03-10

A standard cell-based implementation of a digital optoelectronic neural-network architecture is presented. The overall structure of the multilayer perceptron network that was used, the optoelectronic interconnection system between the layers, and all components required in each layer are defined. The design process from VHDL-based modeling from synthesis and partly automatic placing and routing to the final editing of one layer of the circuit of the multilayer perceptrons are described. A suitable approach for the standard cell-based design of optoelectronic systems is presented, and shortcomings of the design tool that was used are pointed out. The layout for the microelectronic circuit of one layer in a multilayer perceptron neural network with a performance potential 1 magnitude higher than neural networks that are purely electronic based has been successfully designed.

Silk-based biomaterials functionalized with fibronectin type II promotes cell adhesion.

PubMed

Pereira, Ana Margarida; Machado, Raul; da Costa, André; Ribeiro, Artur; Collins, Tony; Gomes, Andreia C; Leonor, Isabel B; Kaplan, David L; Reis, Rui L; Casal, Margarida

2017-01-01

The objective of this work was to exploit the fibronectin type II (FNII) module from human matrix metalloproteinase-2 as a functional domain for the development of silk-based biopolymer blends that display enhanced cell adhesion properties. The DNA sequence of spider dragline silk protein (6mer) was genetically fused with the FNII coding sequence and expressed in Escherichia coli. The chimeric protein 6mer+FNII was purified by non-chromatographic methods. Films prepared from 6mer+FNII by solvent casting promoted only limited cell adhesion of human skin fibroblasts. However, the performance of the material in terms of cell adhesion was significantly improved when 6mer+FNII was combined with a silk-elastin-like protein in a concentration-dependent behavior. With this work we describe a novel class of biopolymer that promote cell adhesion and potentially useful as biomaterials for tissue engineering and regenerative medicine. This work reports the development of biocompatible silk-based composites with enhanced cell adhesion properties suitable for biomedical applications in regenerative medicine. The biocomposites were produced by combining a genetically engineered silk-elastin-like protein with a genetically engineered spider-silk-based polypeptide carrying the three domains of the fibronectin type II module from human metalloproteinase-2. These composites were processed into free-standing films by solvent casting and characterized for their biological behavior. To our knowledge this is the first report of the exploitation of all three FNII domains as a functional domain for the development of bioinspired materials with improved biological performance. The present study highlights the potential of using genetically engineered protein-based composites as a platform for the development of new bioinspired biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Gold nanoparticles for non-invasive cell tracking with CT imaging

NASA Astrophysics Data System (ADS)

Meir, Rinat; Betzer, Oshra; Barnoy, Eran; Motiei, Menachem; Popovtzer, Rachela

2018-02-01

Cell-based therapies use living cells with therapeutic traits to treat various diseases. This is a beneficial alternative for diseases that existing medicine cannot cure efficiently. However, inconsistent results in clinical trials are preventing the advancement and implementation of cell-based therapy. In order to explain such results, there is a need to discover the fate of the transplanted cells. To answer this need, we developed a technique for noninvasive in vivo cell tracking, which uses gold nanoparticles as contrast agents for CT imaging. Herein, we investigate the design principles of this technique for intramuscular transplantation of therapeutic cells. Longitudinal studies were performed, demonstrating the ability to track cells over long periods of time. As few as 500 cells could be detected and a way to quantify the number of cells visualized by CT was demonstrated. This cell-tracking technology has the potential to become an essential tool in pre-clinical studies as well as in clinical trials and advance cell therapy.