WorldWideScience

Sample records for cell junctions correlates

  1. Loss of intercellular junctional communication correlates with metastatic potential in mammary adenocarcinoma cells.

    OpenAIRE

    Nicolson, G. L.; Dulski, K M; Trosko, J E

    1988-01-01

    A series of rat 13762NF mammary adenocarcinoma cell sublines and clones of various spontaneous pulmonary metastatic potentials from the mammary fat pads of syngeneic rats were examined for their intercellular junctional communication. Using the scrape-loading dye-transfer technique to introduce Lucifer yellow (Mr 457) into cells, we measured the abilities of 13762NF cells to transfer dye to adjacent cells. There was an excellent correlation between loss of Lucifer yellow dye transfer and spon...

  2. Correlative microscopy of radial junction nanowire solar cells using nanoindent position markers

    Czech Academy of Sciences Publication Activity Database

    Fejfar, Antonín; Hývl, Matěj; Vetushka, Aliaksi; Pikna, Peter; Hájková, Zdeňka; Ledinský, Martin; Kočka, Jan; Klapetek, P.; Marek, A.; Mašková, A.; Vyskočil, J.; Merkel, J.; Becker, Ch.; Itoh, T.; Misra, S.; Foldyna, M.; Yu, L.; Roca i Cabarrocas, P.

    2015-01-01

    Roč. 135, SI (2015), s. 106-112. ISSN 0927-0248 R&D Projects: GA MŠk 7E10061; GA MŠk(CZ) LM2011026; GA ČR GA13-12386S EU Projects: European Commission(XE) 240826 Grant ostatní: AVČR(CZ) M100101216; AVČR(CZ) M100101217 Institutional support: RVO:68378271 Keywords : radial junction solar cells * silicon nanowires * thin film s * structural disorder * conductive AFM * nanoindentation * correlative microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.337, year: 2014

  3. Investigating inhomogeneous electronic properties of radial junction solar cells using correlative microscopy

    Czech Academy of Sciences Publication Activity Database

    Müller, Martin; Hývl, Matěj; Kratzer, M.; Teichert, C.; Misra, S.; Foldyna, M.; Yu, L.; Roca i Cabarrocas, P.; Itoh, T.; Hájková, Zdeňka; Vetushka, Aliaksi; Ledinský, Martin; Kočka, Jan; Fejfar, Antonín

    2015-01-01

    Roč. 54, č. 8 (2015), "08KA08-1"-"08KA08-5". ISSN 0021-4922 R&D Projects: GA ČR GA14-15357S; GA MŠk(CZ) 7AMB14ATE004; GA ČR GA13-25747S; GA ČR GA13-12386S; GA MŠk(CZ) LM2011026; GA ČR GB14-37427G Grant ostatní: AVČR(CZ) M100101217 Institutional support: RVO:68378271 Keywords : solar cells * radial junctions * silicon nanowires * correlative microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.127, year: 2014

  4. Effects of phenol on barrier function of a human intestinal epithelial cell line correlate with altered tight junction protein localization

    International Nuclear Information System (INIS)

    Phenol contamination of soil and water has raised concerns among people living near phenol-producing factories and hazardous waste sites containing the chemical. Phenol, particularly in high concentrations, is an irritating and corrosive substance, making mucosal membranes targets of toxicity in humans. However, few data on the effects of phenol after oral exposure exist. We used an in vitro model employing human intestinal epithelial cells (SK-CO15) cultured on permeable supports to examine effects of phenol on epithelial barrier function. We hypothesized that phenol disrupts epithelial barrier by altering tight junction (TJ) protein expression. The dose-response effect of phenol on epithelial barrier function was determined using transepithelial electrical resistance (TER) and FITC-dextran permeability measurements. We studied phenol-induced changes in cell morphology and expression of several tight junction proteins by immunofluorescence and Western blot analysis. Effects on cell viability were assessed by MTT, Trypan blue, propidium iodide and TUNEL staining. Exposure to phenol resulted in decreased TER and increased paracellular flux of FITC-dextran in a dose-dependent manner. Delocalization of claudin-1 and ZO-1 from TJs to cytosol correlated with the observed increase in permeability after phenol treatment. Additionally, the decrease in TER correlated with changes in the distribution of a membrane raft marker, suggesting phenol-mediated effects on membrane fluidity. Such observations were independent of effects of phenol on cell viability as enhanced permeability occurred at doses of phenol that did not cause cell death. Overall, these findings suggest that phenol may affect transiently the lipid bilayer of the cell membrane, thus destabilizing TJ-containing microdomains.

  5. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  6. Modelling of Dual-Junction Solar Cells including Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Abdelaziz Amine

    2013-01-01

    Full Text Available Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The purpose of this work is to contribute to the investigation of the tunnel electrical resistance of such a multi-junction cell through the analysis of the current-voltage (J-V characteristics under illumination. Our approach is based on an equivalent circuit model of a diode for each subcell. We examine the effect of tunnel resistance on the performance of a multi-junction cell using minimization of the least squares technique.

  7. Solar cell junction temperature measurement of PV module

    KAUST Repository

    Huang, B.J.

    2011-02-01

    The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

  8. Modelling of Dual-Junction Solar Cells including Tunnel Junction

    OpenAIRE

    Abdelaziz Amine; Yamina Mir; Mimoun Zazoui

    2013-01-01

    Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The p...

  9. Strongly Correlated Fractional Quantum Hall Line Junctions

    OpenAIRE

    Zuelicke, U.; Shimshoni, E.

    2002-01-01

    We have studied a clean finite-length line junction between interacting counterpropagating single-branch fractional-quantum-Hall edge channels. Exact solutions for low-lying excitations and transport properties are obtained when the two edges belong to quantum Hall systems with different filling factors and interact via the long-range Coulomb interaction. Charging effects due to the coupling to external edge-channel leads are fully taken into account. Conductances and power laws in the curren...

  10. Gap Junctions: The Claymore for Cancerous Cells

    Directory of Open Access Journals (Sweden)

    Ailar Nakhlband

    2011-07-01

    Full Text Available Introduction: Gap junctions play an important role in the cell proliferation in mammalian cells as well as carcinogenesis. However, there are controversial issues about their role in cancer pathogenesis. This study was designed to evaluate genotoxicity and cytotoxicity of Carbenoxolone (CBX as a prototype of inter-cellular gap junction blocker in MCF7 and BT20 human breast cancer cells. Methods: The MCF7and BT20 human breast cancer cell lines were cultivated, and treated at designated confluency with different doses of CBX. Cellular cytotoxicity was examined using standard colorimetric assay associated with cell viability tests. Gene expression evaluation was carried out using real time polymerase chain reaction (PCR. Results: MCF7 and BT20 cells were significantly affected by CBX in a dose dependent manner in cell viability assays. Despite varying expression of genes, down regulation of pro- and anti-apoptotic genes was observed in these cells. Conclusion: Based upon this investigation, it can be concluded that CBX could affect both low and high proliferative types of breast cancer cell lines and disproportionate down regulation of both pre- and anti-apoptotic genes may be related to interacting biomolecules, perhaps via gap junctions.

  11. Junctional communication of embryonic cells after induction

    Institute of Scientific and Technical Information of China (English)

    ZengMibai; JiangWansu

    1990-01-01

    Cell couplings before and after neural induction in embryos of Cynops orientalis were studied by means of single cell injection of Lucifer Yellow.Differences both in incidence and the extent of cell couplings were demonstrated.Results of cell couplings were correlated with electron microscopic observations of freeze-etching replicas.

  12. Role of autophagy in the regulation of epithelial cell junctions.

    Science.gov (United States)

    Nighot, Prashant; Ma, Thomas

    2016-01-01

    Autophagy is a cell survival mechanism by which bulk cytoplasmic material, including soluble macromolecules and organelles, is targeted for lysosomal degradation. The role of autophagy in diverse cellular processes such as metabolic stress, neurodegeneration, cancer, aging, immunity, and inflammatory diseases is being increasingly recognized. Epithelial cell junctions play an integral role in the cell homeostasis via physical binding, regulating paracellular pathways, integrating extracellular cues into intracellular signaling, and cell-cell communication. Recent data indicates that cell junction composition is very dynamic. The junctional protein complexes are actively regulated in response to various intra- and extra-cellular clues by intracellular trafficking and degradation pathways. This review discusses the recent and emerging information on how autophagy regulates various epithelial cell junctions. The knowledge of autophagy regulation of epithelial junctions will provide further rationale for targeting autophagy in a wide variety of human disease conditions. PMID:27583189

  13. Phase dynamics in graphene-based Josephson junctions in the presence of thermal and correlated fluctuations

    OpenAIRE

    Guarcello, Claudio; Valenti, Davide; Spagnolo, Bernardo

    2014-01-01

    In this work we study by numerical methods the phase dynamics in ballistic graphene-based short Josephson junctions. The supercurrent through a graphene junction shows a non-sinusoidal phase-dependence, unlike a conventional junction ruled by the well-known d.c. Josephson relation. A superconductor-graphene-superconductor system exhibits superconductive quantum metastable states similar to those present in normal current-biased JJs. We explore the effects of thermal and correlated fluctuation...

  14. The effect of nearest neighbor spin-singlet correlations in conventional graphene SNS Josephson junctions

    OpenAIRE

    Black-Schaffer, Annica M.; Doniach, Sebastian

    2008-01-01

    Using the self-consistent tight-binding Bogoliubov-de Gennes formalism we have studied the effect of nearest neighbor spin-singlet bond (SB) correlations on Josephson coupling and proximity effect in graphene SNS Josephson junctions with conventional s-wave superconducting contacts. Despite the s-wave superconducting state in the contacts, the SB pairing state inside the junction has d-wave symmetry and clean, sharp interface junctions resemble a 'bulk-meets-bulk' situation with very little i...

  15. Systematic optimization of quantum junction colloidal quantum dot solar cells

    Science.gov (United States)

    Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Tang, Jiang; Kramer, Illan J.; Ning, Zhijun; Sargent, Edward H.

    2012-10-01

    The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1% under AM1.5 simulated solar illumination.

  16. CHLORAL HYDRATE DECREASES GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS

    Science.gov (United States)

    Chloral hydrate decreases gap junction communication in rat liver epithelial cells Gap junction communication (GJC) is involved in controlling cell proliferation and differentiation. Connexins (Cx) that make up these junctions are composed of a closely related group of m...

  17. CANDU bundle junction. Misalignment probability and pressure-drop correlation

    International Nuclear Information System (INIS)

    The pressure drop over the bundle junction is an important component of the pressure drop in a CANDU (Canada Deuterium Uranium) fuel channel. This component can represent from ∼ 15% for aligned bundles to ∼ 26% for rotationally misaligned bundles, and is dependent on the degree of misalignment. The geometry of the junction increases the mixing between subchannels, and hence improves the thermal performance of the bundle immediately downstream. It is therefore important to model the junction's performance adequately. This paper summarizes a study sponsored by COG (CANDU Owners Group) and an NSERC (National Science and Engineering Research Council) Industrial Research Grant, undertaken, at CRL (Chalk River Laboratories) to identify and develop a bundle-junction model for potential implementation in the ASSERT (Advanced Solution of Subchannel Equations in Reactor Thermalhydraulics) subchannel code. The work reported in this paper consists of two components of this project: an examination of the statistics of bundle misalignment, demonstrating that there are no preferred positions for the bundles and therefore all misalignment angles are equally possible; and, an empirical model for the single-phase pressure drop across the junction as a function of the misalignment angle. The second section of this paper includes a brief literature review covering the experimental, analytical and numerical studies concerning the single-phase pressure drop across bundle junctions. 32 refs., 9 figs

  18. Abrogation of junctional adhesion molecule-A expression induces cell apoptosis and reduces breast cancer progression.

    Directory of Open Access Journals (Sweden)

    Masato Murakami

    Full Text Available Intercellular junctions promote homotypic cell to cell adhesion and transfer intracellular signals which control cell growth and apoptosis. Junctional adhesion molecule-A (JAM-A is a transmembrane immunoglobulin located at tight junctions of normal epithelial cells of mammary ducts and glands. In the present paper we show that JAM-A acts as a survival factor for mammary carcinoma cells. JAM-A null mice expressing Polyoma Middle T under MMTV promoter develop significantly smaller mammary tumors than JAM-A positive mice. Angiogenesis and inflammatory or immune infiltrate were not statistically modified in absence of JAM-A but tumor cell apoptosis was significantly increased. Tumor cells isolated from JAM-A null mice or 4T1 cells incubated with JAM-A blocking antibodies showed reduced growth and increased apoptosis which paralleled altered junctional architecture and adhesive function. In a breast cancer clinical data set, tissue microarray data show that JAM-A expression correlates with poor prognosis. Gene expression analysis of mouse tumor samples showed a correlation between genes enriched in human G3 tumors and genes over expressed in JAM-A +/+ mammary tumors. Conversely, genes enriched in G1 human tumors correlate with genes overexpressed in JAM-A-/- tumors. We conclude that down regulation of JAM-A reduces tumor aggressive behavior by increasing cell susceptibility to apoptosis. JAM-A may be considered a negative prognostic factor and a potential therapeutic target.

  19. Efficiency limits for single-junction and tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Meillaud, F.; Shah, A.; Droz, C.; Vallat-Sauvain, E.; Miazza, C. [Institute of Microtechnology (IMT), University of Neuchatel, A.-L Breguet 2, 2000 Neuchatel (Switzerland)

    2006-11-23

    Basic limitations of single-junction and tandem p-n and p-i-n diodes are established from thermodynamical considerations on radiative recombination and semi-empirical considerations on the classical diode equations. These limits are compared to actual values of short-circuit current, open-circuit voltage, fill factor and efficiency for amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) silicon solar cells. For single-junction cells, major efficiency gains should be achievable by increasing the short-circuit current density by better light trapping. The limitations of p-i-n junctions are estimated from recombination effects in the intrinsic layer. The efficiency of double-junction cells is presented as a function of the energy gap of top and bottom cells, confirming the 'micromorph' tandem (a-Si:H/{mu}c-Si:H) as an optimum combination of tandem solar cells. (author)

  20. No junctional communication between epithelial cells in hydra

    DEFF Research Database (Denmark)

    de Laat, S W; Tertoolen, L G; Grimmelikhuijzen, C J

    1980-01-01

    Diffusion gradients of morphogens have been inferred as a basis for the control of morphogenesis in hydra, and morphogenetic substances have been found which, on the basis of their molecular weight (MW), should be able to pass gap junctions. There have been several reports of the presence of gap...... junctions between epithelial cells of hydra. However, until now, there has been no report published on whether these junctions enable the epithelial cells to exchange molecules of small molecular weight, as has been described in other organisms. Therefore we decided to investigate the communicative...... properties of the junctional membranes by electrophysiological methods and by intracellular-dye iontophoresis. We report here that no electrotonic coupling is detectable between epithelial cells of Hydra attenuata in: (1) intact animals, (2) head-regenerating animals, (3) cell re-aggregates, and (4) hydra...

  1. Low-Cost Multi-Junction Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR project will provide a pathway to dramatically reduce the cost of multi-junction solar cells. The project leverages a TRL6 micropackaging process...

  2. Nanostructured thin films for multiband-gap silicon triple junction solar cells

    OpenAIRE

    R. E. I. Schropp; Li, H. B. T.; Franken, R.H.; Rath, J.K.; van der Werf, C.H.M.; Schuttauf, J.A.; Stolk, R.L.

    2008-01-01

    By implementing nanostructure in multiband-gap proto-Si/proto-SiGe/nc-Si:H triple junction n–i–p solar cells, a considerable improvement in performance has been achieved. The unalloyed active layers in the top and bottom cell of these triple junction cells are deposited by Hot-Wire CVD. A significant current enhancement is obtained by using textured Ag/ZnO back contacts instead of plain stainless steel. We studied the correlation between the integrated current density in the long-wavelength r...

  3. Full potential of radial junction Si thin film solar cells with advanced junction materials and design

    Science.gov (United States)

    Qian, Shengyi; Misra, Soumyadeep; Lu, Jiawen; Yu, Zhongwei; Yu, Linwei; Xu, Jun; Wang, Junzhuan; Xu, Ling; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-07-01

    Combining advanced materials and junction design in nanowire-based thin film solar cells requires a different thinking of the optimization strategy, which is critical to fulfill the potential of nano-structured photovoltaics. Based on a comprehensive knowledge of the junction materials involved in the multilayer stack, we demonstrate here, in both experimental and theoretical manners, the potential of hydrogenated amorphous Si (a-Si:H) thin film solar cells in a radial junction (RJ) configuration. Resting upon a solid experimental basis, we also assess a more advanced tandem RJ structure with radially stacking a-Si:H/nanocrystalline Si (nc-Si:H) PIN junctions, and show that a balanced photo-current generation with a short circuit current density of Jsc = 14.2 mA/cm2 can be achieved in a tandem RJ cell, while reducing the expensive nc-Si:H absorber thickness from 1-3 μ m (in planar tandem cells) to only 120 nm. These results provide a clearly charted route towards a high performance Si thin film photovoltaics.

  4. Gap Junctions and Biophysical Regulation of Bone Cells

    OpenAIRE

    Lloyd, Shane A. J.; Donahue, Henry J.

    2010-01-01

    Communication between osteoblasts, osteoclasts, and osteocytes is integral to their ability to build and maintain the skeletal system and respond to physical signals. Various physiological mechanisms, including nerve communication, hormones, and cytokines, play an important role in this process. More recently, the important role of direct, cell–cell communication via gap junctions has been established. In this review, we demonstrate the integral role of gap junctional intercellular communicat...

  5. Polymer light-emitting electrochemical cells with frozen junctions

    Science.gov (United States)

    Gao, Jun; Li, Yongfang; Yu, Gang; Heeger, Alan J.

    1999-10-01

    We report on polymer light-emitting electrochemical cells (LECs) with frozen p-i-n junctions. The dynamic p-i-n junction in polymer LECs is stabilized by lowering the temperature below the glass transition temperature of the ion-transport polymer. Detailed studies have shown that the frozen p-i-n junction in LECs based on the luminescent polymer poly[5-(2'ethylhexyloxy)-2-methoxy-1,4-phenylene vinylene] and polyethylene oxide containing lithium triflate (PEO:LiCF3SO3) is stable at temperatures up to 200 K. Frozen-junction LECs offer a number of advantages; they exhibit unipolar light emission, balanced injection, fast response, high brightness, low operating voltage, and insensitivity to electrode materials and film thickness.

  6. Systematic optimization of quantum junction colloidal quantum dot solar cells

    KAUST Repository

    Liu, Huan

    2012-01-01

    The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1 under AM1.5 simulated solar illumination. © 2012 American Institute of Physics.

  7. Alteration of cadherin isoform expression and inhibition of gap junctions in stomach carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To explore cell malignant phenotype correlated changes of cell surface adhesion molecules and cell-cell communication in carcinogenesis, human stomach transformed and cancer cell lines were investigated. Expressions of E-cadherin, N-cadherin, ?-catenin, ?-catenin as well as gap junction (GJ) protein Cx32 were studied by utilization of immunoblotting, immunocytochemical and fluorescent dye transfer methods. Mammalian normal stomach mucosal cells expressed E-cadherin but not N-cadherin. E-cadherin immunofluorescence was detected at cell membranous adherens junctions (AJ) where colocalization with immunofluorescent staining of inner surface adhesion plaque proteins ?- and ?-catenins was observed. The existence of E-cadherin/ catenin (?-, ?-) protein complexes as AJ was suggested. In transformed and stomach cancer cells E-cadherin was inhibited, instead, N-cadherin was expressed and localized at membranous AJ where co-staining with ?- and ?-catenin fluorescence was observed. Formation of N-cadherin/catenin (?-, ?-) protein complex at AJs of transformed and cancer cells was suggested. The above observations were further supported by immunoblotting results. Normal stomach muscosal and transformed cells expressed Cx32 at membranous GJ and were competent of gap junction communication (GJIC). In stomach cancer cells, Cx32 was inhibited and GJIC was defective. The results suggested that changes of signal pathways mediated by both cell adhesion and cell communication systems are associated intracellular events of stomach carcinogenesis. The alteration of cadherin isoform from E- to N-cadherin in transformed and stomach cancer cells is the first report.

  8. Treponema pallidum Invades Intercellular Junctions of Endothelial Cell Monolayers

    Science.gov (United States)

    Thomas, D. Denee; Navab, Mahamad; Haake, David A.; Fogelman, Alan M.; Miller, James N.; Lovett, Michael A.

    1988-05-01

    The pathogenesis of syphilis reflects invasive properties of Treponema pallidum, but the actual mode of tissue invasion is unknown. We have found two in vitro parallels of treponemal invasiveness. We tested whether motile T. pallidum could invade host cells by determining the fate of radiolabeled motile organisms added to a HeLa cell monolayer; 26% of treponemes associated with the monolayer in a trypsin-resistant niche, presumably between the monolayer and the surface to which it adhered, but did not attain intracellularity. Attachment of T. pallidum to cultured human and rabbit aortic and human umbilical vein endothelial cells was 2-fold greater than to HeLa cells. We added T. pallidum to aortic endothelial cells grown on membrane filters under conditions in which tight intercellular junctions had formed. T. pallidum was able to pass through the endothelial cell monolayers without altering tight junctions, as measured by electrical resistance. In contrast, heat-killed T. pallidum and the nonpathogen Treponema phagedenis biotype Reiter failed to penetrate the monolayer. Transmission electron micrographs of sections of the monolayer showed T. pallidum in intercellular junctions. Our in vitro observations suggest that these highly motile spirochetes may leave the circulation by invading the junctions between endothelial cells.

  9. Mammary epithelial cell phagocytosis downstream of TGF-β3 is characterized by adherens junction reorganization.

    Science.gov (United States)

    Fornetti, J; Flanders, K C; Henson, P M; Tan, A-C; Borges, V F; Schedin, P

    2016-02-01

    After weaning, during mammary gland involution, milk-producing mammary epithelial cells undergo apoptosis. Effective clearance of these dying cells is essential, as persistent apoptotic cells have a negative impact on gland homeostasis, future lactation and cancer susceptibility. In mice, apoptotic cells are cleared by the neighboring epithelium, yet little is known about how mammary epithelial cells become phagocytic or whether this function is conserved between species. Here we use a rat model of weaning-induced involution and involuting breast tissue from women, to demonstrate apoptotic cells within luminal epithelial cells and epithelial expression of the scavenger mannose receptor, suggesting conservation of phagocytosis by epithelial cells. In the rat, epithelial transforming growth factor-β (TGF-β) signaling is increased during involution, a pathway known to promote phagocytic capability. To test whether TGF-β enhances the phagocytic ability of mammary epithelial cells, non-transformed murine mammary epithelial EpH4 cells were cultured to achieve tight junction impermeability, such as occurs during lactation. TGF-β3 treatment promoted loss of tight junction impermeability, reorganization and cleavage of the adherens junction protein E-cadherin (E-cad), and phagocytosis. Phagocytosis correlated with junction disruption, suggesting junction reorganization is necessary for phagocytosis by epithelial cells. Supporting this hypothesis, epithelial cell E-cad reorganization and cleavage were observed in rat and human involuting mammary glands. Further, in the rat, E-cad cleavage correlated with increased γ-secretase activity and β-catenin nuclear localization. In vitro, pharmacologic inhibitors of γ-secretase or β-catenin reduced the effect of TGF-β3 on phagocytosis to near baseline levels. However, β-catenin signaling through LiCl treatment did not enhance phagocytic capacity, suggesting a model in which both reorganization of cell junctions and

  10. Quantum-Tuned Two-Junction Solar Cells

    KAUST Repository

    Wang, Xihua

    2011-01-01

    We report quantum-size-effect tuned tandem solar cells. Our two-junction photovoltaic devices employ light-absorbing material of a single composition and use two rationally-selected nanoparticle sizes to harvest the sun’s broad spectrum.

  11. Endothelial cell senescence is associated with disrupted cell-cell junctions and increased monolayer permeability

    Directory of Open Access Journals (Sweden)

    Krouwer Vincent J D

    2012-08-01

    Full Text Available Abstract Background Cellular senescence is associated with cellular dysfunction and has been shown to occur in vivo in age-related cardiovascular diseases such as atherosclerosis. Atherogenesis is accompanied by intimal accumulation of LDL and increased extravasation of monocytes towards accumulated and oxidized LDL, suggesting an affected barrier function of vascular endothelial cells. Our objective was to study the effect of cellular senescence on the barrier function of non-senescent endothelial cells. Methods Human umbilical vein endothelial cells were cultured until senescence. Senescent cells were compared with non-senescent cells and with co-cultures of non-senescent and senescent cells. Adherens junctions and tight junctions were studied. To assess the barrier function of various monolayers, assays to measure permeability for Lucifer Yellow (LY and horseradish peroxidase (PO were performed. Results The barrier function of monolayers comprising of senescent cells was compromised and coincided with a change in the distribution of junction proteins and a down-regulation of occludin and claudin-5 expression. Furthermore, a decreased expression of occludin and claudin-5 was observed in co-cultures of non-senescent and senescent cells, not only between senescent cells but also along the entire periphery of non-senescent cells lining a senescent cell. Conclusions Our findings show that the presence of senescent endothelial cells in a non-senescent monolayer disrupts tight junction morphology of surrounding young cells and increases the permeability of the monolayer for LY and PO.

  12. Simulation of Tunnel Junction in Cascade Solar Cell (GaAs/Ge) Using AMPS-1D

    OpenAIRE

    Benmoussa Dennai; H. Ben Slimane; Helmaoui, A.

    2014-01-01

    The development of the tunnel junction interconnect was key the first two-terminal monolithic, multi-junction solar cell development. This paper describes simulation for the tunnel junction (GaAs) between top cell (GaAs) and bottom cell (Ge). This solar cell cascade was simulated when using one dimensional simulation program called analysis of microelectronic and photonic structures (AMPS-1D). In the simulation, the thickness of the tunnel junction layer was varied from 10 to 50 nm. By varyin...

  13. Gap junction communication between cells aggregated on a cellulose-coated polystyrene: influence of connexin 43 phosphorylation.

    Science.gov (United States)

    Faucheux, N; Zahm, J M; Bonnet, N; Legeay, G; Nagel, M D

    2004-06-01

    The appropriate functioning of tissues and organ systems depends on intercellular communication such as gap junctions formed by connexin (Cx) protein channels between adjacent cells. We have previously shown that Swiss 3T3 cells aggregated on hydrophilic cellulose substratum Cuprophan (CU) establish short linear gap junctions composed of Cx 43 in cell surface plaques. This phenomenon seems to depend on the high intracellular cyclic AMP (cAMP) concentration triggered by attachment of the cells to CU. We have now used a cellulose-coated polystyrene inducing the same cell behaviour to analyse the gap junction communication between aggregated cells. The transfer of the dye Lucifer Yellow (LY) between cells showed that cells aggregated on cellulose substratum rapidly (within 90 min) establish functional gap junctions. Inhibitors of cAMP protein kinase (PKI) or protein kinase C (GF109203X) both inhibited the diffusion of LY between neighbouring cells. Western blot analysis showed that this change in permeability was correlated with a decrease in Cx 43 phosphorylation. Thus, cellulose substrata seem to induce cell-cell communication through Cx 43 phosphorylation modulated by PKA and PKC. To understand the mechanisms by which a substratum regulates gap junctional communication is critically important for the emerging fields of tissue engineering and biohybrid devices. PMID:14751734

  14. The effect of electronic correlations on Josephson current and proximity effect in SNS graphene junctions

    Science.gov (United States)

    Black-Schaffer, Annica; Doniach, Sebastian

    2008-03-01

    Using the self-consistent tight-binding Bogoliubov-de Gennes (BdG) formalism, we investigate the proximity effect and current-phase relationship in SNS graphene Josephson junctions. Both short and long junctions are considered, as well as different doping levels of the graphene. For short junctions at zero doping in the uncorrelated regime our results agree with those found using the non self-consistent Dirac-BdG formalism [1]. We introduce electronic correlations in the Hamiltonian by including the intrinsic nearest-neighbor spin-singlet coupling present in p π-bonded planar organic molecules. We study the possibility of coupling this intrinsic s- or d-wave superconducting pairing [2] to the extrinsic s-wave order parameter induced by the metal electrodes. The intrinsic d-wave solution, favored in doped graphene, appears for longer doped junctions. For short junctions, the s-wave solution can occur, although the result is sensitive to the type of interface. We also report on the two different intrinsic superconducting states' influence on the supercurrent. [1] M. Titov et al. PRB 74 041401 (2006) [2] A. Black-Schaffer et al. PRB 75 134512 (2007)

  15. Cell junction proteins within the cochlea:A review of recent research

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Bohua Hu; Shiming Yang

    2015-01-01

    Cell—cell junctions in the cochlea are highly complex and well organized. The role of these junctions is to maintain structural and functional integrity of the cochlea. In this review, we describe classification of cell junction-associated proteins identified within the cochlea and provide a brief overview of the function of these proteins in adherent junctions, gap junctions and tight junctions. Copyright © 2016, PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  16. Modeling the Effect of P-N Junction Depth on the Output of Planer and Rectangular Textured Solar Cells

    Directory of Open Access Journals (Sweden)

    F. Jahanshah

    2009-01-01

    Full Text Available Problem statement: High cost of the solar cells is one of the important limitations in extensively using of the photovoltaic panels. Thin monocrystalline silicon solar cell could be reduce the cost but lost the absorption efficiency. Surface texturing help to enhance absorption. Using of advance texturing by diffraction grating was suggested for high absorption. It is necessary to investigate the scattering effect of diffraction grating with other solar cell parameter for optimization. In first step we concentrate on p-n junction position impact by modeling. Approach: The effect of position of p-n junction on the output current for both micro rectangular texturing and planer surface in solar cell has been investigated by ray tracing. Modeling of nine pairs solar cells with the same texture and planer surfaces but with different p-n junction position are done by using Atlas software. The output short current is a criterion for determining of efficiency performance. By comparing of the short current for each pair we was find the impacts of texturing and p-n junction depth on the monocrystalline thin film. Results: Light scattering due to diffraction grating inside the silicon with rectangular depth of 5 µm and a range of 5-40 µm p-n junction depths are investigated. The difference of short current in textured to bare silicon showed the enhancement from 4-8 µA when the p-n junction depths vary from 5-45 µm. Conclusions: Comparison of short current output confirms the correlation between p-n junction depth and texturing. Advanced texturing improve the solar cell efficiency but the effectiveness change with the p-n junction depth and need a simultaneous optimization for getting the high efficiency solar cell.

  17. Simulation of Tunnel Junction in Cascade Solar Cell (GaAs/Ge Using AMPS-1D

    Directory of Open Access Journals (Sweden)

    Benmoussa Dennai

    2014-11-01

    Full Text Available The development of the tunnel junction interconnect was key the first two-terminal monolithic, multi-junction solar cell development. This paper describes simulation for the tunnel junction (GaAs between top cell (GaAs and bottom cell (Ge. This solar cell cascade was simulated when using one dimensional simulation program called analysis of microelectronic and photonic structures (AMPS-1D. In the simulation, the thickness of the tunnel junction layer was varied from 10 to 50 nm. By varying thickness of tunnel junction layer the simulated device performance was demonstrate in the form of current-voltage(I-V characteristics and quantum efficiency (QE.

  18. Thermodynamic limit of bifacial double-junction tandem solar cells

    Science.gov (United States)

    Ryyan Khan, M.; Alam, Muhammad A.

    2015-11-01

    A traditional single-junction solar panel cannot harness ground-scattered light (albedo reflectance, RA ), and also suffers from the fundamental sub-band-gap and the thermalization losses. In this paper, we explain how a "bifacial tandem" panel would dramatically reduce these losses, with corresponding improvement in thermodynamic performance. Our study predicts (i) the optimum combination of the band-gaps, empirically given by Eg(t ) o p t≈Eg(b ) o p t(2 +RA)/3 +(1 -RA) and the (ii) corresponding optimum normalized output power given by ηT(op t ) *≈RA (2 ηSJ (o p t ) ) +(1 -RA ) ηDJ (o p t ) . Empirically, ηT(op t ) * interpolates between the thermodynamic efficiency limit of classical double-junction tandem cell ( ηDJ ) and twice that of a single-junction cell ( ηSJ ). We conclude by explaining how the fundamental loss mechanisms evolve with RA in a bifacial tandem cell.

  19. Urinary NGAL Levels Correlate with Differential Renal Function in Patients with Ureteropelvic Junction Obstruction Undergoing Pyeloplasty

    Science.gov (United States)

    Cost, Nicholas G.; Noh, Paul H.; Devarajan, Prasad; Ivancic, Vesna; Reddy, Pramod P.; Minevich, Eugene; Bennett, Michael; Haffner, Christopher; Schulte, Marion; DeFoor, W. Robert

    2014-01-01

    Purpose: Recent investigations described the use of NGAL, a sensitive biomarker for kidney injury, in the setting of ureteropelvic junction obstruction. We prospectively evaluated urinary NGAL levels in the affected renal pelvis and bladder of children with ureteropelvic junction obstruction undergoing unilateral dismembered pyeloplasty. Our hypothesis was that higher NGAL in the kidney and bladder would correlate with decreased ipsilateral differential function. Materials and Methods: We performed a prospective cohort study in patients treated with unilateral dismembered pyeloplasty from 2010 to 2012. Urine was obtained intraoperatively from the bladder and obstructed renal pelvis. A control population of unaffected children was recruited to provide a voided bladder specimen. Bladder NGAL levels were compared between the study and control populations. We tested our study hypothesis by correlating bladder and renal pelvic NGAL levels with the differential renal function of the affected kidney. Results: A total of 61 patients with a median age at surgery of 1.62 years (range 0.12 to 18.7) were enrolled in the study. Median bladder NGAL was 18.6 ng/mg (range 1.4-1,650.8) and median renal pelvic NGAL was 26.2 ng/mg (range 1.2-18,034.5, p = 0.004). Median bladder NGAL was significantly higher than in controls (p = 0.004). The correlation of bladder and renal pelvic NGAL with differential renal function was r = −0.359 (p = 0.004) and r = −0.383 (p = 0.002), respectively. Conclusions: Bladder NGAL is increased in children with ureteropelvic junction obstruction. Renal pelvic and bladder normalized urinary NGAL levels correlate inversely with the relative function of the affected kidney in cases of unilateral ureteropelvic junction obstruction. PMID:23791906

  20. Junctional communication is induced in migrating capillary endothelial cells.

    Science.gov (United States)

    Pepper, M S; Spray, D C; Chanson, M; Montesano, R; Orci, L; Meda, P

    1989-12-01

    Using an in vitro model in which a confluent monolayer of capillary endothelial cells is mechanically wounded, gap junction-mediated intercellular communication has been studied by loading the cells with the fluorescent dye, Lucifer Yellow. Approximately 40-50% of the cells in a nonwounded confluent monolayer were coupled in groups of four to five cells (basal level). Basal levels of communication were also observed in sparse and preconfluent cultures, but were reduced in postconfluent monolayers. 30 min after wounding, coupling was markedly reduced between cells lining the wound. Communication at the wound was partially reestablished by 2 h, exceeded basal levels after 6 h and reached a maximum after 24 h, at which stage approximately 90% of the cells were coupled in groups of six to seven cells. When the wound had closed (after 8 d), the increase in communication was no longer observed. Induction of wound-associated communication was unaffected by exposure of the cells to the DNA synthesis inhibitor mitomycin C, but was prevented by the protein synthesis inhibitor, cycloheximide. The induction of wound-associated communication was also inhibited when migration was prevented by placing the cells immediately after wounding at 22 degrees C or after exposure to cytochalasin D, suggesting that the increase in communication is dependent on cells migrating into the wound area. In contrast, migration was not prevented when coupling was blocked by exposure of the cells to retinoic acid, although this agent did disrupt the characteristic sheet-like pattern of migration typically seen during endothelial repair. These results suggest that junctional communication may play an important role in wound repair, possibly by coordinating capillary endothelial cell migration. PMID:2592412

  1. Differences in regulation of tight junctions and cell morphology between VHL mutations from disease subtypes

    Directory of Open Access Journals (Sweden)

    Isanova Bella

    2009-07-01

    Full Text Available Abstract Background In von Hippel-Lindau (VHL disease, germline mutations in the VHL tumor suppressor gene cause clear cell renal carcinomas, hemangioblastomas, and pheochromocytomas. The VHL gene product is part of an ubiquitin E3 ligase complex and hypoxia-inducible factor alpha (HIF-α is a key substrate, although additional VHL functions have been described. A genotype-phenotype relationship exists in VHL disease such that specific VHL mutations elicit certain subsets of these tumors. Here, we examine VHL genotype-phenotype correlations at the cellular level, focusing on the regulation of tight junctions and cell morphology. Methods Wild-type and various mutant VHL proteins representing VHL disease subtypes were stably expressed in 3 VHL-negative renal carcinoma cell lines. Using these cell lines, the roles of various VHL-associated cellular functions in regulation of cell morphology were investigated. Results As a whole, type 1 mutants varied greatly from type 2 mutants, demonstrating high levels of HIF-2α, cyclin D1 and α5 integrin, lower p27 levels, and a spindly, fibroblastic cellular appearance. Type 2 mutations demonstrated an epithelial morphology similar to wild-type VHL in the majority of the renal cell lines used. Knockdown of p27 in cells with wild-type VHL led to perturbations of both epithelial morphology and ZO-1 localization to tight junctions. ZO-1 localization correlated well with VHL disease subtypes, with greater mislocalization observed for genotypes associated with a higher risk of renal carcinoma. HIF-2α knockdown in 786-O partially restored ZO-1 localization, but did not restore an epithelial morphology. Conclusion VHL has both HIF-α dependent and HIF-α independent functions in regulating tight junctions and cell morphology that likely impact the clinical phenotypes seen in VHL disease.

  2. Differences in regulation of tight junctions and cell morphology between VHL mutations from disease subtypes

    International Nuclear Information System (INIS)

    In von Hippel-Lindau (VHL) disease, germline mutations in the VHL tumor suppressor gene cause clear cell renal carcinomas, hemangioblastomas, and pheochromocytomas. The VHL gene product is part of an ubiquitin E3 ligase complex and hypoxia-inducible factor alpha (HIF-α) is a key substrate, although additional VHL functions have been described. A genotype-phenotype relationship exists in VHL disease such that specific VHL mutations elicit certain subsets of these tumors. Here, we examine VHL genotype-phenotype correlations at the cellular level, focusing on the regulation of tight junctions and cell morphology. Wild-type and various mutant VHL proteins representing VHL disease subtypes were stably expressed in 3 VHL-negative renal carcinoma cell lines. Using these cell lines, the roles of various VHL-associated cellular functions in regulation of cell morphology were investigated. As a whole, type 1 mutants varied greatly from type 2 mutants, demonstrating high levels of HIF-2α, cyclin D1 and α5 integrin, lower p27 levels, and a spindly, fibroblastic cellular appearance. Type 2 mutations demonstrated an epithelial morphology similar to wild-type VHL in the majority of the renal cell lines used. Knockdown of p27 in cells with wild-type VHL led to perturbations of both epithelial morphology and ZO-1 localization to tight junctions. ZO-1 localization correlated well with VHL disease subtypes, with greater mislocalization observed for genotypes associated with a higher risk of renal carcinoma. HIF-2α knockdown in 786-O partially restored ZO-1 localization, but did not restore an epithelial morphology. VHL has both HIF-α dependent and HIF-α independent functions in regulating tight junctions and cell morphology that likely impact the clinical phenotypes seen in VHL disease

  3. Cdc42 is crucial for the maturation of primordial cell junctions in keratinocytes independent of Rac1

    DEFF Research Database (Denmark)

    Du, Dan; Pedersen, Esben; Wang, Zhipeng;

    2008-01-01

    -deficient immortalized and primary keratinocytes form only punctate primordial cell contacts in vitro, which cannot mature into belt-like junctions. This defect was independent of enhanced degradation of beta-catenin, but correlated to an impaired activation and localization of aPKCzeta in the Cdc42-null...

  4. Mechanically Stacked Four-Junction Concentrator Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Myles A.; Geisz, John F.; Ward, J. Scott; Garcia, Ivan; Friedman, Daniel J.; King, Richard R.; Chiu, Philip T.; France, Ryan M.; Duda, Anna; Olavarria, Waldo J.; Young, Michelle; Kurtz, Sarah R.

    2015-06-14

    Multijunction solar cells can be fabricated by bonding together component cells that are grown separately. Because the component cells are each grown lattice-matched to suitable substrates, this technique allows alloys of different lattice constants to be combined without the structural defects introduced when using metamorphic buffers. Here we present results on the fabrication and performance of four-junction mechanical stacks composed of GaInP/GaAs and GaInAsP/GaInAs tandems, grown on GaAs and InP substrates, respectively. The two tandems were bonded together with a low-index, transparent epoxy that acts as an omni-directional reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the sub-bandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and thus higher subcell voltage, compared with GaAs subcells without enhanced internal optics; all four subcells exhibit excellent material quality. The device was fabricated with four contact terminals so that each tandem can be operated at its maximum power point, which raises the cumulative efficiency and decreases spectral sensitivity. Efficiencies exceeding 38% at one-sun have been demonstrated. Eliminating the series resistance is the key challenge for the concentrator cells. We will discuss the performance of one-sun and concentrator versions of the device, and compare the results to recently fabricated monolithic four-junction cells.

  5. Tripple Junction Solar Cells With 30.0% Efficiency And Next Generation Cell Concepts

    Science.gov (United States)

    Kostler, W.; Meusel, M.; Kubera, T.; Torunski, T.

    2011-10-01

    This paper presents the data of the AZUR SPACE 3G30 cell. With its 30% BOL efficiency for AM0, it marks the final stage of lattice-matched space triple-junction cells. Furthermore, a summary is given on the roadmap for the development of future cell concept in terms of higher efficiency and increase of cell size.

  6. Self-organizing actomyosin patterns on the cell cortex at epithelial cell-cell junctions.

    Science.gov (United States)

    Moore, Thomas; Wu, Selwin K; Michael, Magdalene; Yap, Alpha S; Gomez, Guillermo A; Neufeld, Zoltan

    2014-12-01

    The behavior of actomyosin critically determines morphologically distinct patterns of contractility found at the interface between adherent cells. One such pattern is found at the apical region (zonula adherens) of cell-cell junctions in epithelia, where clusters of the adhesion molecule E-cadherin concentrate in a static pattern. Meanwhile, E-cadherin clusters throughout lateral cell-cell contacts display dynamic movements in the plane of the junctions. To gain insight into the principles that determine the nature and organization of these dynamic structures, we analyze this behavior by modeling the 2D actomyosin cell cortex as an active fluid medium. The numerical simulations show that the stability of the actin filaments influences the spatial structure and dynamics of the system. We find that in addition to static Turing-type patterns, persistent dynamic behavior occurs in a wide range of parameters. In the 2D model, mechanical stress-dependent actin breakdown is shown to produce a continuously changing network of actin bridges, whereas with a constant breakdown rate, more isolated clusters of actomyosin tend to form. The model qualitatively reproduces the dynamic and stable patterns experimentally observed at the junctions between epithelial cells. PMID:25468344

  7. S–I–S Josephson junction with a correlated insulator below its S–I transition

    Energy Technology Data Exchange (ETDEWEB)

    Porter, C.D. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Kim, Kwangmoo [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Stroud, D., E-mail: stroud@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States)

    2014-03-15

    Highlights: • We model an S–I–S junction, whose insulating layer is actually a superconductor below its S–I transition. • We demonstrate that such a structure indeed behaves like a single Josephson junction. • The coherence length diverges as the insulating layer approaches its S–I transition • The model may describe so-called Cooper pair insulators studied in some experiments. - Abstract: We consider a Josephson junction composed of two superconducting (S) regions separated by an insulating (I) region, but with the special property that the S and the I regions are superconducting films respectively above and below the superconducting–insulating (S–I) transition. To calculate the properties of this junction, we describe the system using an inhomogeneous quantum rotor Hamiltonian with a coupling energy J and spatially varying charging energy U. The ratio J/U is chosen so that it is above the critical value for an S–I transition in the two superconducting regions, but below it in the insulating regime. Using both mean-field theory and perturbation theory, we show that the phase order parameter is finite in the S region and decays exponentially into the I region. Thus, the order parameter, which would be zero in the I region in isolation, is instead rendered nonzero by the adjacent S region, because of a proximity effect. As a result, there is a nonzero coupling energy between the two S regions. We show, using both mean-field theory and a quantum Monte Carlo calculation, that the phase stiffness constant, or helicity modulus, of this junction is nonzero, and falls off exponentially with separation of the two superconductors. We also analytically estimate the dependence of the coupling energy on the properties of the S and I regions, and suggest an analogy with conventional S–N–S junctions. Our results support the conclusion that this S–I–S sandwich structure, with a correlated insulating region, can be viewed as a single effective

  8. Culture and identification of stem cells of uterine junctional zone

    Directory of Open Access Journals (Sweden)

    Kang KANG

    2015-04-01

    Full Text Available Objective To establish a method for isolation, culture, and identification of stem cells in uterine junctional zone (uJZSCs. Methods Specimens of uterus muscle layer at uterine junctional zone (uJZ were harvested under aseptic condition, and they digested, cultivated and amplified using trypsogen and collagenaseⅠ. The morphology of uJZSCs was observed with inverted microscope, and cell viability and phenotype were analyzed by flow cytometry. The adipogenic, osteogenic and chondrogenic differentiation was induced in vitro, and their biological growth characteristic was identified by CCK-8 marking. Results The cells were adhered after passage, and they presented long spindle in shape. Flow cytometry showed that the expressions of CD90, CD73, CD105, CD29, CD44, CD13, CD166, and HLA-ABC marking was also positive, while they were negative for CD34, CD45, CD14, HLA-DR and CD19. The CCK-8 growth curve was S-shaped. The induced differentiation experiments indicated that uJZSCs could be induced into osteoblast, adipocyte and chondrocytes. Conclusion uJZSCs possess a strong proliferation capacity, and they might become a new source of mesenchymal stem cells. DOI: 10.11855/j.issn.0577-7402.2015.03.01

  9. TCAD analysis of graphene silicon Schottky junction solar cell

    Science.gov (United States)

    Kuang, Yawei; Liu, Yushen; Ma, Yulong; Xu, Jing; Yang, Xifeng; Feng, Jinfu

    2015-08-01

    The performance of graphene based Schottky junction solar cell on silicon substrate is studied theoretically by TCAD Silvaco tools. We calculate the current-voltage curves and internal quantum efficiency of this device at different conditions using tow dimensional model. The results show that the power conversion efficiency of Schottky solar cell dependents on the work function of graphene and the physical properties of silicon such as thickness and doping concentration. At higher concentration of 1e17cm-3 for n-type silicon, the dark current got a sharp rise compared with lower doping concentration which implies a convert of electron emission mechanism. The biggest fill factor got at higher phos doping predicts a new direction for higher performance graphene Schottky solar cell design.

  10. The nanostructure of myoendothelial junctions contributes to signal rectification between endothelial and vascular smooth muscle cells

    DEFF Research Database (Denmark)

    Brasen, Jens Christian; Jacobsen, Jens Christian Brings; von Holstein-Rathlou, Niels-Henrik

    2012-01-01

    can easily drive a concentration change in the head of the myoendothelial protrusion. Subsequently the signal can be amplified in the head, and activate the entire cell. In contrast, a signal in the cell from which the myoendothelial junction originates will be attenuated and delayed in the neck...... region as it travels into the head of the myoendothelial junction and the neighboring cell....

  11. RhoA-JNK Regulates the E-Cadherin Junctions of Human Gingival Epithelial Cells.

    Science.gov (United States)

    Lee, G; Kim, H J; Kim, H-M

    2016-03-01

    The junctional epithelium (JE) is unique with regard to its wide intercellular spaces and sparsely developed intercellular junctions. Thus, knowledge of the molecular mechanisms that regulate the formation of the intercellular junctions of the junctional epithelium may be essential to understand the pathophysiology of the JE. HOK-16B cells, a normal human gingival epithelial cell line, were used to identify the molecules involved in the regulation of the formation of intercellular E-cadherin junctions between human gingival epithelial cells. Activation of c-Jun N-terminal kinase (JNK) disrupted the intercellular junctions through the dissociation of E-cadherin. The role of JNK in the formation of these E-cadherin junctions was further confirmed by demonstrating that JNK inhibition induced the formation of intercellular E-cadherin junctions. The upstream signaling of JNK was also examined. Activation of the small GTPase RhoA disrupted the formation of E-cadherin junctions between HOK-16B cells, which was accompanied by JNK activation. Disruption of these intercellular junctions upon RhoA activation was prevented when JNK activity was inhibited. In contrast, RhoA inactivation led to HOK-16B cell aggregation and the formation of intercellular junctions, even under conditions in which the cellular junctions were naturally disrupted by growth on a strongly adhesive surface. Furthermore, the JE of mouse molars had high JNK activity associated with low E-cadherin expression, which was reversed in the other gingival epithelia, including the sulcular epithelium. Interestingly, JNK activity was increased in cells grown on a solid surface, where cells showed higher RhoA activity than those grown on soft surfaces. Together, these results indicate that the decreased formation of intercellular E-cadherin junctions within the JE may be coupled to high JNK activity, which is activated by the upregulation of RhoA on solid tooth surfaces. PMID:26635280

  12. Gap Junctions

    OpenAIRE

    Goodenough, Daniel A.; Paul, David L.

    2009-01-01

    Gap junctions are aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hex...

  13. Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells

    International Nuclear Information System (INIS)

    In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels

  14. Enhancement of nearest neighbor spin-singlet correlations in d-wave SNS graphene Josephson junctions

    Science.gov (United States)

    Black-Schaffer, Annica; Doniach, Sebastian

    2009-03-01

    Using the self-consistent tight-binding Bogoliubov-de Gennes (BdG) formalism we investigate the effect of nearest neighbor spin-singlet bond (SB) correlations in a graphene SNS Josephson junction with d-wave superconducting contacts. All pπ-bonded planar organic molecules, of which graphene is the infinite extension, show a preference for SB over polar configurations, as originally captured by Pauling's idea of resonating valence bonds. At strong enough coupling and/or high doping levels, these correlations will give rise to a d-wave superconducting state. However, the estimated coupling strength in graphene would require a doping level not currently experimentally achievable by a gating bias. We demonstrate that by creating a graphene SNS Josephson junction with d-wave contacts, for example by depositing a high-Tc cuprate on top of the graphene, it should be possible to enhance the effect of the SB correlations and see clear signatures of d-wave pairing in proximity effect, superconducting decay length, and supercurrent.

  15. 1.00 MeV proton radiation resistance studies of single-junction and single gap dual-junction amorphous-silicon alloy solar cells

    Science.gov (United States)

    Abdulaziz, Salman; Payson, J. S.; Li, Yang; Woodyard, James R.

    1990-01-01

    A comparative study of the radiation resistance of a-Si:H and a-SiGe:H single-junction and a-Si:H dual-junction solar cells was conducted. The cells were irradiated with 1.00-MeV protons with fluences of 1.0 x 10 to the 14th, 5.0 x 10 to the 14th and 1.0 x 10 to the 15th/sq cm and characterized using I-V and quantum efficiency measurements. The radiation resistance of single-junction cells cannot be used to explain the behavior of dual-junction cells at a fluence of 1.0 x 10 to the 15th/sq cm. The a-Si H single-junction cells degraded the least of the three cells; a-SiGe:H single-junction cells showed the largest reduction in short-circuit current, while a-Si:H dual-junction cells exhibited the largest degradation in the open-circuit voltage. The quantum efficiency of the cells degraded more in the red part of the spectrum; the bottom junction degrades first in dual-junction cells.

  16. Temperature Characteristics Analysis of Triple-Junction Solar Cell under Concentrated Conditions using Spice Diode Model

    Science.gov (United States)

    Sakurada, Yuya; Ota, Yasuyuki; Nishioka, Kensuke

    2011-12-01

    Using spice diode model, the temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under concentrated light conditions were analyzed in detail. The current-voltage (I-V) characteristics of the single-junction solar cells (InGaP, InGaAs, and Ge solar cells) were measured at various temperatures. From dark I-V characteristics of each single-junction solar cell, the diode parameters and temperature exponents were extracted. The extracted diode parameters and temperature exponents were applied to the equivalent circuit model for the triple-junction solar cell, and the solar cell performance was calculated with considering the temperature characteristics of series resistance. There was good agreement between the measured and calculated I-V characteristics of the triple-junction solar cell at various temperatures under concentrated light conditions.

  17. Investigation of multi-junction solar cells using electrostatic force microscopy methods

    Energy Technology Data Exchange (ETDEWEB)

    Moczała, M., E-mail: magdalena.moczala@pwr.wroc.pl [Wrocław University of Technology, Faculty of Microsystem Electronics and Photonics, Division of Metrology of Micro- and Nanostructures, ul. Z. Janiszewskiego 11/17, 50-372 Wrocław (Poland); Sosa, N.; Topol, A. [IBM Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Gotszalk, T. [Wrocław University of Technology, Faculty of Microsystem Electronics and Photonics, Division of Metrology of Micro- and Nanostructures, ul. Z. Janiszewskiego 11/17, 50-372 Wrocław (Poland)

    2014-06-01

    Multi-junction III–V solar cells are designed to have a much broader absorption of the solar spectrum than Si-based or single junctions, thus yield the highest conversion. The conversion efficiency can be further scaled with sun concentration. The ability of high conversion efficiencies makes multi-junction prime candidates for fine-tuning explorations aimed at getting closer to the theoretical efficiencies. In this paper, we report on electrostatic force microscopy (EFM) measurements of the built-in potential of multi-junction III–V semiconductor-based solar cells. Kelvin probe force microscopy (KPFM) was employed to qualitatively study the width and electrical properties of individual junctions, i.e., built-in potential, activity, and thickness of the p–n junctions. In addition, the voltage drops across individual solar cell p–n junctions were measured using Kelvin probe microscopy under various operation conditions: dark; illuminated; short-circuit; and biased. We present a method which enables the measurement of a working structure, while focusing on the electrical characteristics of an individual junction by virtue of selecting the spectral range of the illumination used. We show that these pragmatic studies can provide a feedback to improve photovoltaic device design, particularly of operation under a current mismatched situation. This new analysis technique offers additional insights into behavior of the multi-junction solar cell and shows promise for further progress in this field. - Highlights: • We explore the electronic structure of III–V based high efficiency solar cells. • Qualitative study of the solar cell operation characteristics is presented. • Quantitative study of the electrostatic landscape of operational high efficiency devices is presented. • Precise identification of the epitaxially grown p–n and tunnel junctions in the multi-junction solar cell. • Influence of illumination conditions and cell biasing on each p

  18. Investigation of multi-junction solar cells using electrostatic force microscopy methods

    International Nuclear Information System (INIS)

    Multi-junction III–V solar cells are designed to have a much broader absorption of the solar spectrum than Si-based or single junctions, thus yield the highest conversion. The conversion efficiency can be further scaled with sun concentration. The ability of high conversion efficiencies makes multi-junction prime candidates for fine-tuning explorations aimed at getting closer to the theoretical efficiencies. In this paper, we report on electrostatic force microscopy (EFM) measurements of the built-in potential of multi-junction III–V semiconductor-based solar cells. Kelvin probe force microscopy (KPFM) was employed to qualitatively study the width and electrical properties of individual junctions, i.e., built-in potential, activity, and thickness of the p–n junctions. In addition, the voltage drops across individual solar cell p–n junctions were measured using Kelvin probe microscopy under various operation conditions: dark; illuminated; short-circuit; and biased. We present a method which enables the measurement of a working structure, while focusing on the electrical characteristics of an individual junction by virtue of selecting the spectral range of the illumination used. We show that these pragmatic studies can provide a feedback to improve photovoltaic device design, particularly of operation under a current mismatched situation. This new analysis technique offers additional insights into behavior of the multi-junction solar cell and shows promise for further progress in this field. - Highlights: • We explore the electronic structure of III–V based high efficiency solar cells. • Qualitative study of the solar cell operation characteristics is presented. • Quantitative study of the electrostatic landscape of operational high efficiency devices is presented. • Precise identification of the epitaxially grown p–n and tunnel junctions in the multi-junction solar cell. • Influence of illumination conditions and cell biasing on each p

  19. Tendon cells in vivo form a three dimensional network of cell processes linked by gap junctions.

    OpenAIRE

    McNeilly, C M; Banes, A J; Benjamin, M; Ralphs, J.R.

    1996-01-01

    Tendons respond to mechanical load by modifying their extracellular matrix. The cells therefore sense mechanical load and coordinate an appropriate response to it. We show that tendon cells have the potential to communicate with one another via cell processes and gap junctions and thus could use direct cell/cell communication to detect and/or coordinate their load responses. Unfixed cryosections of adult rat digital flexor tendons were stained with the fluorescent membrane dye DiI to demonstr...

  20. Japanese encephalitis virus disrupts cell-cell junctions and affects the epithelial permeability barrier functions.

    Directory of Open Access Journals (Sweden)

    Tanvi Agrawal

    Full Text Available Japanese encephalitis virus (JEV is a neurotropic flavivirus, which causes viral encephalitis leading to death in about 20-30% of severely-infected people. Although JEV is known to be a neurotropic virus its replication in non-neuronal cells in peripheral tissues is likely to play a key role in viral dissemination and pathogenesis. We have investigated the effect of JEV infection on cellular junctions in a number of non-neuronal cells. We show that JEV affects the permeability barrier functions in polarized epithelial cells at later stages of infection. The levels of some of the tight and adherens junction proteins were reduced in epithelial and endothelial cells and also in hepatocytes. Despite the induction of antiviral response, barrier disruption was not mediated by secreted factors from the infected cells. Localization of tight junction protein claudin-1 was severely perturbed in JEV-infected cells and claudin-1 partially colocalized with JEV in intracellular compartments and targeted for lysosomal degradation. Expression of JEV-capsid alone significantly affected the permeability barrier functions in these cells. Our results suggest that JEV infection modulates cellular junctions in non-neuronal cells and compromises the permeability barrier of epithelial and endothelial cells which may play a role in viral dissemination in peripheral tissues.

  1. Silicon multi-junctional solar cells with vertical p-n junctions: Evolution, technology, applications, and new opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Simakin, V.V. [All-Russian Institute of Electrical Engineering, Moscow (Russian Federation); Strebkov, D.S.; Tyukhov, I.I. [All-Russian Institute for Electrification of Agriculture, Moscow (Russian Federation)

    2004-07-01

    This paper describes the evolution of the silicon multi-junctional solar cells with vertical p-n junctions (SCVJ) and its present status, mainly, at the base of researches carried out in Russia and the USA. The number of SCVJ produced in the whole world is quite low in comparison with the traditional SC. At the same time according to the laws of technical cenosis (as in biology - biocenosis) increasing of unification and size of SC leads to increasing economic efficiency of solar energy and, yet, diversification (developing and creating other types of SC, and other principles) leads to higher competitiveness and occupying new niches. (orig.)

  2. A surface plasmon enabled liquid-junction photovoltaic cell.

    Science.gov (United States)

    Lee, Woo-ram; Mubeen, Syed; Stucky, Galen D; Moskovits, Martin

    2015-01-01

    Plasmonic nanosystems have recently been shown to be capable of functioning as photovoltaics and of carrying out redox photochemistry, purportedly using the energetic electrons and holes created following plasmonic decay as charge carriers. Although such devices currently have low efficiency, they already manifest a number of favorable characteristics, such as their tunability over the entire solar spectrum and a remarkable resistance to photocorrosion. Here, we report a plasmonic photovoltaic using a 25 μm thick electrolytic liquid junction which supports the iodide/triiodide (I-/I3-) redox couple. The device produces photocurrent densities in excess of 40 μA cm(-2), an open circuit voltage (Voc) of ∼0.24 V and a fill factor of ∼0.5 using AM 1.5 G solar radiation at 100 mW cm(-2). The photocurrent and the power conversion efficiency are primarily limited by the low light absorption in the 2-D gold nanoparticle arrays. The use of a liquid junction greatly reduces dielectric breakdown in the oxide layers utilized, which must be very thin for optimal performance, leading to a great improvement in the long-term stability of the cell's performance. PMID:25740725

  3. The Effects of MEO Radiation Environment on Triple-Junction GaAs Solar Cells

    Science.gov (United States)

    Xin, Gao; Sheng-sheng, Yang; Yun-fei, Wang; Zhan-zu, Feng

    The effects of MEO (Altitude 20,000 km, Inclination 56°) radiation environment on the degradation of triple-junction GaAs cells (Manufactured in China) are investigated to provide the reference for solar array design. The results are presented on the performance degradation of triple-junction GaAs cells with various thicknesses of shielding silica coverglass in the MEO radiation environment, using the displacement damage dose methodology for analyzing and modeling. Degradation at different electron energies has been correlated with displacement damage dose. The maximum power of the cells without coverglass will be seriously degraded, reducing it to below 20% of the initial value by the accumulating proton dose at the end of a 1-year-mission. However, using a 100-μm-thick coveglass, the maximum power of the cells can be maintanined at 90% of the initial value. While a 100-μm-thick silica coverglass can practically block off the effects of protons on the GaAs cells in the MEO environment, its effect is not so pronounced for electrons. The use of the coverglass is of vital importance for shielding the damages by low energy protons in the MEO orbit.

  4. Gap Junctions

    OpenAIRE

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of ...

  5. Cell-Specific Expression of Connexins and Evidence of Restricted Gap Junctional Coupling between Glial Cells and between Neurons

    OpenAIRE

    Rash, John E.; Yasumura, Thomas; Dudek, F. Edward; NAGY, JAMES I.

    2001-01-01

    The transmembrane connexin proteins of gap junctions link extracellularly to form channels for cell-to-cell exchange of ions and small molecules. Two primary hypotheses of gap junction coupling in the CNS are the following: (1) generalized coupling occurs between neurons and glia, with some connexins expressed in both neurons and glia, and (2) intercellular junctional coupling is restricted to specific coupling partners, with different connexins expressed in each cell type. There is consensus...

  6. ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCTED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS

    Science.gov (United States)

    ORIENTATION REQUIREMENT TO DETECT MAGNETIC FIELD-INDUCED ALTERATION OF GAP JUNCTION COMMUNICATION IN EPITHELIAL CELLS. OBJECTIVE: We have shown that functional gap junction communication as measured by Lucifer yellow dye transfer (DT) in Clone-9 rat liver epithelial cells, c...

  7. ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jorgensen, N R; Geist, S T; Civitelli, R;

    1997-01-01

    stores. In one model, IP3 traverses gap junctions and initiates the release of intracellular calcium stores in neighboring cells. Alternatively, calcium waves may be mediated not by gap junctional communication, but rather by autocrine activity of secreted ATP on P2 purinergic receptors. We studied...... connexin43 (Cx43), are well dye coupled, and lack P2U receptors, transmitted slow gap junction-dependent calcium waves that did not require release of intracellular calcium stores. UMR 106-01 cells predominantly express the gap junction protein connexin 45 (Cx45), are poorly dye coupled, and express P2U...... receptors; they propagated fast calcium waves that required release of intracellular calcium stores and activation of P2U purinergic receptors, but not gap junctional communication. ROS/P2U transfectants and UMR/Cx43 transfectants expressed both types of calcium waves. Gap junction-independent, ATP...

  8. Microscale electrochemical cell using plaster (CaSO4) as liquid junction

    OpenAIRE

    Yuthapong Udnan

    2008-01-01

    A microscale apparatus for electrochemical cell in which plaster (CaSO4) was used as liquid junction has been developed. A glass tube (0.5 cm ID x 5.0 cm) was used to prepare each half-cell. The potentials of the resulting galvanic cells were measured by a multimetre and were compared to those of the galvanic cells in which agar was used as liquid junction. It was found that the potentials produced by the galvanic cells with plaster as liquid junction are not significantly different from tho...

  9. Neisseria gonorrhoeae induced disruption of cell junction complexes in epithelial cells of the human genital tract.

    Science.gov (United States)

    Rodríguez-Tirado, Carolina; Maisey, Kevin; Rodríguez, Felipe E; Reyes-Cerpa, Sebastián; Reyes-López, Felipe E; Imarai, Mónica

    2012-03-01

    Pathogenic microorganisms, such as Neisseria gonorrhoeae, have developed mechanisms to alter epithelial barriers in order to reach subepithelial tissues for host colonization. The aim of this study was to examine the effects of gonococci on cell junction complexes of genital epithelial cells of women. Polarized Ishikawa cells, a cell line derived from endometrial epithelium, were used for experimental infection. Infected cells displayed a spindle-like shape with an irregular distribution, indicating potential alteration of cell-cell contacts. Accordingly, analysis by confocal microscopy and cellular fractionation revealed that gonococci induced redistribution of the adherens junction proteins E-cadherin and its adapter protein β-catenin from the membrane to a cytoplasmic pool, with no significant differences in protein levels. In contrast, gonococcal infection did not induce modification of either expression or distribution of the tight junction proteins Occludin and ZO-1. Similar results were observed for Fallopian tube epithelia. Interestingly, infected Ishikawa cells also showed an altered pattern of actin cytoskeleton, observed in the form of stress fibers across the cytoplasm, which in turn matched a strong alteration on the expression of fibronectin, an adhesive glycoprotein component of extracellular matrix. Interestingly, using western blotting, activation of the ERK pathway was detected after gonococcal infection while p38 pathway was not activated. All effects were pili and Opa independent. Altogether, results indicated that gonococcus, as a mechanism of pathogenesis, induced disruption of junction complexes with early detaching of E-cadherin and β-catenin from the adherens junction complex, followed by a redistribution and reorganization of actin cytoskeleton and fibronectin within the extracellular matrix. PMID:22146107

  10. ESD test for triple-junction solar cells with monolithic diode

    OpenAIRE

    Nozaki, Yukishige; Masui, Hirokazu; Toyoda, Kazuhiro; 野崎 幸重; 増井 博一; 豊田 和弘; Cho, Mengu

    2008-01-01

    Recently many spacecraft use Triple-Junction (TJ) solar cells as their primary electrical power source because of their excellent efficiency. However it is also known that triple-junction solar cells are easy to be broken by a low reverse bias voltage. Therefore a discrete by-pass diode should be connected to every solar cell in parallel for the shadow protection. Under these circumstances, TJ solar cells with integrate Monolithic Diode (MD) have been introduced to market recently. In the CIC...

  11. Boosting spin-caloritronic effects by attractive correlations in molecular junctions

    Science.gov (United States)

    Weymann, Ireneusz

    2016-01-01

    In nanoscopic systems quantum confinement and interference can lead to an enhancement of thermoelectric properties as compared to conventional bulk materials. For nanostructures, such as molecules or quantum dots coupled to external leads, the thermoelectric figure of merit can reach or even exceed unity. Moreover, in the presence of external magnetic field or when the leads are ferromagnetic, an applied temperature gradient can generate a spin voltage and an associated spin current flow in the system, which makes such nanostructures particularly interesting for future thermoelectric applications. In this study, by using the numerical renormalization group method, we examine the spin-dependent thermoelectric transport properties of a molecular junction involving an orbital level with attractive Coulomb correlations coupled to ferromagnetic leads. We analyze how attractive correlations affect the spin-resolved transport properties of the system and find a nontrivial dependence of the conductance and tunnel magnetoresistance on the strength and sign of those correlations. We also demonstrate that attractive correlations can lead to an enhancement of the spin thermopower and the figure of merit, which can be controlled by a gate voltage.

  12. Quantum correlation between the junction-voltage fluctuation and the photon-number fluctuation in a semiconductor laser

    Science.gov (United States)

    Richardson, W. H.; Yamamoto, Y.

    1991-01-01

    The photon-number fluctuation of the external field from a semiconductor laser - which was reduced to below the standard quantum limit - is shown to be correlated with the measured junction-voltage noise. The spectral density of the sum of the photon-number fluctuation and junction-voltage fluctuation falls below the squeezed photon-number fluctuation. This confirms the theoretical predictions that this correlation, which originates in the dipole interaction between the internal field and electron-hole pairs, extends into the quantum regime.

  13. Microscale electrochemical cell using plaster (CaSO4 as liquid junction

    Directory of Open Access Journals (Sweden)

    Yuthapong Udnan

    2008-10-01

    Full Text Available A microscale apparatus for electrochemical cell in which plaster (CaSO4 was used as liquid junction has been developed. A glass tube (0.5 cm ID x 5.0 cm was used to prepare each half-cell. The potentials of the resulting galvanic cells were measured by a multimetre and were compared to those of the galvanic cells in which agar was used as liquid junction. It was found that the potentials produced by the galvanic cells with plaster as liquid junction are not significantly different from those of the cells with agar as liquid junction and close to the theoretical values. In addition, when the developed apparatus was used for the study of electrolysis of potassium iodide solution, it was found that the electrolytic cell made from the microscale apparatus with plaster liquid junction can distinctly separate the reactions occurring at the anode and the cathode. Moreover, the lifetime of the plaster liquid junction is much greater than that of the agar liquid junction.

  14. Shear-induced reorganization of renal proximal tubule cell actin cytoskeleton and apical junctional complexes.

    Science.gov (United States)

    Duan, Yi; Gotoh, Nanami; Yan, Qingshang; Du, Zhaopeng; Weinstein, Alan M; Wang, Tong; Weinbaum, Sheldon

    2008-08-12

    In this study, we demonstrate that fluid shear stress (FSS)-induced actin cytoskeletal reorganization and junctional formation in renal epithelial cells are nearly completely opposite the corresponding changes in vascular endothelial cells (ECs) [Thi MM et al. (2004) Proc Natl Acad Sci USA 101:16483-16488]. Mouse proximal tubule cells (PTCs) were subjected to 5 h of FSS (1 dyn/cm(2)) to investigate the dynamic responses of the cytoskeletal distribution of filamentous actin (F-actin), ZO-1, E-cadherin, vinculin, and paxillin to FSS. Immunofluorescence analysis revealed that FSS caused basal stress fiber disruption, more densely distributed peripheral actin bands (DPABs), and the formation of both tight junctions (TJs) and adherens junctions (AJs). A dramatic reinforcement of vinculin staining was found at the cell borders as well as the cell interior. These responses were abrogated by the actin-disrupting drug, cytochalasin D. To interpret these results, we propose a "junctional buttressing" model for PTCs in which FSS enables the DPABs, TJs, and AJs to become more tightly connected. In contrast, in the "bumper-car" model for ECs, all junctional connections were severely disrupted by FSS. This "junctional buttressing" model explains why a FSS of only 1/10 of that used in the EC study can cause a similarly dramatic, cytoskeletal response in these tall, cuboidal epithelial cells; and why junctional buttressing between adjacent cells may benefit renal epithelium in maximizing flow-activated, brush border-dependent, transcellular salt and water reabsorption. PMID:18685100

  15. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    Science.gov (United States)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  16. Design High-Efficiency III–V Nanowire/Si Two-Junction Solar Cell

    OpenAIRE

    Y Wang; Zhang, Y.; Zhang, D; He, S; Li, X.

    2015-01-01

    In this paper, we report the electrical simulation results of a proposed GaInP nanowire (NW)/Si two-junction solar cell. The NW physical dimensions are determined for optimized solar energy absorption and current matching between each subcell. Two key factors (minority carrier lifetime, surface recombination velocity) affecting power conversion efficiency (PCE) of the solar cell are highlighted, and a practical guideline to design high-efficiency two-junction solar cell is thus provided. Cons...

  17. AlGaAs/GaAs tunnel junctions in a 4-J tandem solar cell

    Institute of Scientific and Technical Information of China (English)

    Lü Siyu; Qu Xiaosheng

    2011-01-01

    The Ⅲ-Ⅴ compound tandem solar cell is a third-generation new style solar cell with ultra-high efficiency.The energy band gaps of the sub-cells in a GaInP/GaAs/InGaAs/Ge 4-J tandem solar cell are 1.8,1.4,1.0and 0.7 eV,respectively.In order to match the currents between sub-cells,tunnel junctions are used to connect the sub-cells.The characteristics of the tunnel junction,the material used in the tunnel junction,the compensation of the tunnel junction to the overall cell's characteristics,the tunnel junction's influence on the current density of sub-cells and the efficiency increase are discussed in the paper.An A1GaAs/GaAs tunnel junction is selected to simulate the cell's overall characteristics by PC 1 D,current densities of 16.02,17.12,17.75 and 17.45 mA/cm2 are observed,with a Voc of 3.246 V,the energy conversion efficiency under AM0 is 33.9%.

  18. Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps

    KAUST Repository

    Takaku, Yasuharu

    2014-01-07

    Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia.

  19. Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps.

    Science.gov (United States)

    Takaku, Yasuharu; Hwang, Jung Shan; Wolf, Alexander; Böttger, Angelika; Shimizu, Hiroshi; David, Charles N; Gojobori, Takashi

    2014-01-01

    Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia. PMID:24394722

  20. Recent Progress and Spectral Robustness Study for Mechanically Stacked Multi-junction Solar Cells

    Science.gov (United States)

    Zhao, Lu; Flamand, Giovanni; Poortmans, Jef

    2010-10-01

    Multi-terminal mechanically stacked multi-junction solar cells are an attractive candidate for terrestrial concentrator photovoltaics applications. Unlike monolithically integrated multi-junction solar cells which require current matching, all the available photon currents can be fully extracted from each junction of a mechanically stacked solar cell. Therefore, it has a high performance potential, and more importantly is less sensitive to spectrum variations. Lower losses due to current mismatch translate into a higher annual energy output for the mechanical stack. This paper presents the baseline processing developed at imec for the mechanical stacking process, and the most recent cell results by means of this technology. A GaAs-Ge dual-junction mechanically stacked multi-junction solar cell is demonstrated, with 24.7% plus 2.52% under AM1.5g, and 27.7% plus 4.42% under 30Suns concentration. In addition, spectral sensitivity is studied for both monolithically stacked and mechanically stacked solar cells, to learn the influence of spectrum variations on multi-junction solar cell performance. SMARTS model is used to predict the spectral irradiances, with solar radiation and meteorological elements from typical meteorological year 3 (TMY3) data set. The generated spectra are then fed into TCAD numerical simulation tool, to simulate the device performance. The simulation results show a reduced spectral sensitivity for mechanically stacked cell, and there is a 6% relative gain in annual energy production for the site studied (Las Vegas), compared with the monolithic stack.

  1. Performance of multi-junction cells due to illumination distribution across the cell surface

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, R.D., E-mail: s206029578@live.nmmu.ac.za [Nelson Mandela University, Physics Department, P.O. Box 77000, 6031, Port Elizabeth (South Africa); Vorster, F.J; Dyk, E.E van [Nelson Mandela University, Physics Department, P.O. Box 77000, 6031, Port Elizabeth (South Africa)

    2012-05-15

    This paper addresses the influence of illumination distribution on the performance of a high concentration photovoltaic (HCPV) module. CPV systems comprise of optical elements as well as mechanical tracking to concentrate the solar flux onto the solar receiver as well as to keep the system on track with the sun. The performance of the subcells of the multi-junction concentrator cell depends on the optical alignment of the system. Raster scanning of the incident intensity in the optical plane of the receiver and corresponding I-V measurements were used to investigate the influence of illumination distribution on performance. The results show that the illumination distribution that differs between cells does affect the performance of the module. The performance of the subcells of the multi-junction concentrator cell also depends on the optical alignment of the system.

  2. Performance of multi-junction cells due to illumination distribution across the cell surface

    International Nuclear Information System (INIS)

    This paper addresses the influence of illumination distribution on the performance of a high concentration photovoltaic (HCPV) module. CPV systems comprise of optical elements as well as mechanical tracking to concentrate the solar flux onto the solar receiver as well as to keep the system on track with the sun. The performance of the subcells of the multi-junction concentrator cell depends on the optical alignment of the system. Raster scanning of the incident intensity in the optical plane of the receiver and corresponding I–V measurements were used to investigate the influence of illumination distribution on performance. The results show that the illumination distribution that differs between cells does affect the performance of the module. The performance of the subcells of the multi-junction concentrator cell also depends on the optical alignment of the system.

  3. INFLUENCE OF SODIUM ARSENITE ON GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS

    Science.gov (United States)

    Influence of sodium arsenite on gap junction communication in rat-Iiver epitheiial cells. Arsenic is known to cause certain types of cancers, hepatitis, cirrhosis and neurological disorders as well as cardiovascular and reproductive effects and skin lesions. The mechanism...

  4. Chloral hydrate decreases gap junction communications in rat liver epithelial cells

    Science.gov (United States)

    Gap junction communication (GJC) is involved in controlling cell proliferation and differentiation. Alterations in GJC are associated with carcinogenesis, but the mechanisms involvedareunknown.Chloralhydrate(CH), a by-productofchlorinedisinfection ofwater,is carcinogenic in mice,...

  5. Gap junctional protein Cx43 is involved in the communication between extracellular vesicles and mammalian cells

    NARCIS (Netherlands)

    Soares, Ana Rosa; Martins-Marques, Tania; Ribeiro-Rodrigues, Teresa; Ferreira, Joao Vasco; Catarino, Steve; Pinho, Maria Joao; Zuzarte, Monica; Anjo, Sandra Isabel; Manadas, Bruno; Sluijter, Joost P. G.; Pereira, Paulo; Girao, Henrique

    2015-01-01

    Intercellular communication is vital to ensure tissue and organism homeostasis and can occur directly, between neighbour cells via gap junctions (GJ), or indirectly, at longer distances, through extracellular vesicles, including exosomes. Exosomes, as intercellular carriers of messenger molecules, m

  6. Highly efficient organic multi-junction solar cells with a thiophene based donor material

    Energy Technology Data Exchange (ETDEWEB)

    Meerheim, Rico, E-mail: rico.meerheim@iapp.de; Körner, Christian; Leo, Karl, E-mail: karl.leo@iapp.de [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01062 Dresden (Germany)

    2014-08-11

    The efficiency of organic solar cells can be increased by serial stacked subcells even upon using the same absorber material. For the multi-junction devices presented here, we use the small molecule donor material DCV5T-Me. The subcell currents were matched by optical transfer matrix simulation, allowing an efficiency increase from 8.3% for a single junction up to 9.7% for a triple junction cell. The external quantum efficiency of the subcells, measured under appropriate light bias illumination, is spectrally shifted due to the microcavity of the complete stack, resulting in a broadband response and an increased cell current. The increase of the power conversion efficiency upon device stacking is even stronger for large area cells due to higher influence of the resistance of the indium tin oxide anode, emphasizing the advantage of multi-junction devices for large-area applications.

  7. Highly efficient organic multi-junction solar cells with a thiophene based donor material

    International Nuclear Information System (INIS)

    The efficiency of organic solar cells can be increased by serial stacked subcells even upon using the same absorber material. For the multi-junction devices presented here, we use the small molecule donor material DCV5T-Me. The subcell currents were matched by optical transfer matrix simulation, allowing an efficiency increase from 8.3% for a single junction up to 9.7% for a triple junction cell. The external quantum efficiency of the subcells, measured under appropriate light bias illumination, is spectrally shifted due to the microcavity of the complete stack, resulting in a broadband response and an increased cell current. The increase of the power conversion efficiency upon device stacking is even stronger for large area cells due to higher influence of the resistance of the indium tin oxide anode, emphasizing the advantage of multi-junction devices for large-area applications

  8. Neural progenitor cells isolated from the subventricular zone present hemichannel activity and form functional gap junctions with glial cells

    Science.gov (United States)

    Talaverón, Rocío; Fernández, Paola; Escamilla, Rosalba; Pastor, Angel M.; Matarredona, Esperanza R.; Sáez, Juan C.

    2015-01-01

    The postnatal subventricular zone (SVZ) lining the walls of the lateral ventricles contains neural progenitor cells (NPCs) that generate new olfactory bulb interneurons. Communication via gap junctions between cells in the SVZ is involved in NPC proliferation and in neuroblast migration towards the olfactory bulb. SVZ NPCs can be expanded in vitro in the form of neurospheres that can be used for transplantation purposes after brain injury. We have previously reported that neurosphere-derived NPCs form heterocellular gap junctions with host glial cells when they are implanted after mechanical injury. To analyze functionality of NPC-glial cell gap junctions we performed dye coupling experiments in co-cultures of SVZ NPCs with astrocytes or microglia. Neurosphere-derived cells expressed mRNA for at least the hemichannel/gap junction channel proteins connexin 26 (Cx26), Cx43, Cx45 and pannexin 1 (Panx1). Dye coupling experiments revealed that gap junctional communication occurred among neurosphere cells (incidence of coupling: 100%). Moreover, hemichannel activity was also detected in neurosphere cells as evaluated in time-lapse measurements of ethidium bromide uptake. Heterocellular coupling between NPCs and glial cells was evidenced in co-cultures of neurospheres with astrocytes (incidence of coupling: 91.0 ± 4.7%) or with microglia (incidence of coupling: 71.9 ± 6.7%). Dye coupling in neurospheres and in co-cultures was inhibited by octanol, a gap junction blocker. Altogether, these results suggest the existence of functional hemichannels and gap junction channels in postnatal SVZ neurospheres. In addition, they demonstrate that SVZ-derived NPCs can establish functional gap junctions with astrocytes or microglia. Therefore, cell-cell communication via gap junctions and hemichannels with host glial cells might subserve a role in the functional integration of NPCs after implantation in the damaged brain. PMID:26528139

  9. Strongly correlated perovskite fuel cells

    Science.gov (United States)

    Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D.; Ramanathan, Shriram

    2016-06-01

    Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.

  10. Renal pyramid echogenicity in ureteropelvic junction obstruction: correlation between altered echogenicity and differential renal function

    International Nuclear Information System (INIS)

    Improvement in resolution and use of high-frequency transducers in US has enabled visualization of previously unreported changes in medullary pyramid echogenicity in children with obstructive hydronephrosis. To determine whether these unreported changes in echogenicity and morphology of the renal pyramids in ureteropelvic junction (UPJ) obstruction correlate with differential renal function (DRF) of the kidney as determined by technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) scan. Renal sonograms in 60 children with UPJ obstruction were retrospectively reviewed. Children were divided into three groups based on the echogenicity of the pyramids: (1) normal echogenicity of the pyramids, (2) increased echogenicity of the pyramids with maintained corticomedullary differentiation (CMD), and (3) loss of CMD. DRF, as determined by 99mTc-MAG3 scan, of the obstructed kidney of ≥45% was considered normal and of ≤44% was considered abnormal based on a published study correlating histological changes with DRF. Fisher's exact test was performed for assessing the association between DRF and altered echogenicity of the pyramids. In group 1, which consisted of 13 patients with normal pyramids on US, DRF was normal in 11 and abnormal in two. In group 2, which consisted of 33 patients with echogenic pyramids and preserved CMD, DRF was normal in 15 and abnormal in 18. In group 3, which consisted of 14 patients with complete loss of CMD, DRF was normal in 2 and abnormal in 12. There was a strong correlation between abnormal pyramids and DRF (P=0.0009). The risk ratio (RR) of DRF becoming abnormal for those kidneys with abnormal echogenicity of the pyramids with preserved CMD (group 2) compared to normal pyramid echogenicity (group 1) was 1.56 (95% CI 1.088-2.236). The RR of DRF becoming abnormal for those kidneys with loss of CMD (group 3) compared to normal pyramid echogenicity (group 1) was 5.571 (95% CI 1.530-20.294). We observed that in obstructed kidneys the echogenicity

  11. Connexin expression and gap-junctional intercellular communication in ES cells and iPS cells

    Directory of Open Access Journals (Sweden)

    Masahito eOyamada

    2013-07-01

    Full Text Available Pluripotent stem cells, i.e., embryonic stem (ES and induced pluripotent stem (iPS cells, can indefinitely proliferate without commitment and differentiate into all cell lineages. ES cells are derived from the inner cell mass of the preimplantation blastocyst, whereas iPS cells are generated from somatic cells by overexpression of a few transcription factors. Many studies have demonstrated that mouse and human iPS cells are highly similar but not identical to their respective ES cell counterparts. The potential to generate basically any differentiated cell types from these cells offers the possibility to establish new models of mammalian development and to create new sources of cells for regenerative medicine. ES cells and iPS cells also provide useful models to study connexin expression and gap-junctional intercellular communication (GJIC during cell differentiation and reprogramming. In 1996, we reported connexin expression and GJIC in mouse ES cells. Because a substantial number of papers on these subjects have been published since our report, this Mini Review summarizes currently available data on connexin expression and GJIC in ES cells and iPS cells during undifferentiated state, differentiation, and reprogramming.

  12. Ochratoxim A alters cell adhesion and gap junction intercellular communication in MDCK cells

    International Nuclear Information System (INIS)

    Ochratoxin A (OTA) is one of the most potent renal carcinogens studied to date, but the mechanism of tumor formation by ochratoxin A remains largely unknown. Cell adhesion and cell-cell communication participate in the regulation of signaling pathways involved in cell proliferation and growth control and it is therefore not surprising that modulation of cell-cell signaling has been implicated in cancer development. Several nephrotoxicants and renal carcinogens have been shown to alter cell-cell signaling by interference with gap junction intercell communication (GJIC) and/or cell adhesion, and the aim of this study was to determine if disruption of cell-cell interactions occurs in kidney epithelial cells in response to OTA treatment. MDCK cells were treated with OTA (0-50 μM) for up to 24 h and gap junction function was analyzed using the scrape-load/dye transfer assay. In addition, expression and intracellular localization of Cx43, E-cadherin and β-catenin were determined by immunoblot and immunofluorescence analysis. A clear decrease in the distance of dye transfer was evident following treatment with OTA at concentrations/incubation times which did not affect cell viability. Consistent with the functional inhibition of GJIC, treatment with OTA resulted in a dose-dependent decrease in Cx43 expression. In contrast to Cx43, OTA did not alter total amount of the adherens junction proteins E-cadherin and β-catenin. Moreover, Western blot analysis of Triton X-100 soluble and insoluble protein fractions did not indicate translocation of cell adhesion molecules from the membrane to the cytoplasm. However, a ∼78 kDa fragment of β-catenin was detected in the detergent soluble fraction, indicating proteolytic cleavage of β-catenin. Immunofluorescence analysis also revealed changes in the pattern of both β-catenin and E-cadherin labeling, suggesting that OTA may alter cell-adhesion. Taken together, these data support the hypothesis that disruption of cell-cell

  13. Contribution of gap junctional communication between tumor cells and astroglia to the invasion of the brain parenchyma by human glioblastomas

    Directory of Open Access Journals (Sweden)

    Venance Laurent

    2005-02-01

    Full Text Available Abstract Background Gliomas are "intraparenchymally metastatic" tumors, invading the brain in a non-destructive way that suggests cooperation between glioma cells and their environment. Recent studies using an engineered rodent C6 tumor cell line have pointed to mechanisms of invasion that involved gap junctional communication (GJC, with connexin 43 as a substrate. We explored whether this concept may have clinical relevance by analyzing the participation of GJC in human glioblastoma invasion. Results Three complementary in vitro assays were used: (i seeding on collagen IV, to analyze homocellular interactions between tumor cells (ii co-cultures with astrocytes, to study glioblastoma/astrocytes relationships and (iii implantation into organotypic brain slice cultures, that mimic the three-dimensional parenchymal environment. Carbenoxolone, a potent blocker of GJC, inhibited cell migration in the two latter models. It paradoxically increased it in the first one. These results showed that homocellular interaction between tumor cells supports intercellular adhesion, whereas heterocellular glioblastoma/astrocytes interactions through functional GJC conversely support tumor cell migration. As demonstrated for the rodent cell line, connexin 43 may be responsible for this heterocellular functional coupling. Its levels of expression, high in astrocytes, correlated positively with invasiveness in biopsied tumors. Conclusions our results underscore the potential clinical relevance of the concept put forward by other authors based on experiments with a rodent cell line, that glioblastoma cells use astrocytes as a substrate for their migration by subverting communication through connexin 43-dependent gap junctions.

  14. Some features of solar cells with vertical p-n junctions in InP

    International Nuclear Information System (INIS)

    Numeral calculation performed and graphic distribution were given of not equilibrium charge carriers along depth in p- and n-regions of p-n junction in InP at different significance of surface recombination velocity of not equilibrium carriers and at maximum significance of absorption recombination coefficient . At this case is considered lighted surface of diode by radiation falling parallel plane of p-n junction. The optimum size of individual diodes in solar cells battery were defined for achievement of maximum separate coefficient of not equilibrium charge carriers of p-n junctions. The region of spectral sensibilities for solar cells battery with the vertical p-n junctions on InP are estimated and discussed some way of it expanding

  15. Reinforcing endothelial junctions prevents microvessel permeability increase and tumor cell adhesion in microvessels in vivo

    Science.gov (United States)

    Fu, Bingmei M.; Yang, Jinlin; Cai, Bin; Fan, Jie; Zhang, Lin; Zeng, Min

    2015-10-01

    Tumor cell adhesion to the microvessel wall is a critical step during tumor metastasis. Vascular endothelial growth factor (VEGF), a secretion of tumor cells, can increase microvessel permeability and tumor cell adhesion in the microvessel. To test the hypothesis that inhibiting permeability increase can reduce tumor cell adhesion, we used in vivo fluorescence microscopy to measure both microvessel permeability and adhesion rates of human mammary carcinoma MDA-MB-231 cells in post-capillary venules of rat mesentery under the treatment of VEGF and a cAMP analog, 8-bromo-cAMP, which can decrease microvessel permeability. By immunostaining adherens junction proteins between endothelial cells forming the microvessel wall, we further investigated the structural mechanism by which cAMP abolishes VEGF-induced increase in microvessel permeability and tumor cell adhesion. Our results demonstrate that 1) Pretreatment of microvessels with cAMP can abolish VEGF-enhanced microvessel permeability and tumor cell adhesion; 2) Tumor cells prefer to adhere to the endothelial cell junctions instead of cell bodies; 3) VEGF increases microvessel permeability and tumor cell adhesion by compromising endothelial junctions while cAMP abolishes these effects of VEGF by reinforcing the junctions. These results suggest that strengthening the microvessel wall integrity can be a potential approach to inhibiting hematogenous tumor metastasis.

  16. Influence of drugs on gap junctions in glioma cell lines and primary astrocytes in vitro

    OpenAIRE

    Zahra eMoinfar; Hannes eDambach; Pedro Michael Faustmann

    2014-01-01

    Gap junctions (GJs) are hemichannels on cell membrane. Once they are intercellulary connected to the neighboring cells, they build a functional syncytium which allows rapid transfer of ions and molecules between cells. This characteristic makes GJs a potential modulator in proliferation, migration, and development of the cells. So far, several types of GJs are recognized on different brain cells as well as in glioma. Astrocytes, as one of the major cells that maintain neuronal homeostasis, ex...

  17. 7-Ketocholesterol modulates intercellular communication through gap-junction in bovine lens epithelial cells

    Directory of Open Access Journals (Sweden)

    Pereira Paulo

    2004-06-01

    Full Text Available Abstract Background Connexin43 (Cx43 is an integral membrane protein that forms intercellular channels called gap junctions. Intercellular communication in the eye lens relies on an extensive network of gap junctions essential for the maintenance of lens transparency. The association of Cx43 with cholesterol enriched lipid raft domains was recently demonstrated. The objective of this study is to assess if products of cholesterol oxidation (oxysterols affect gap junction intercellular communication (GJIC. Results Primary cultures of lens epithelial cells (LEC were incubated with 7-ketocholesterol (7-Keto, 25-hydroxycholesterol (25-OH or cholesterol and the subcellular distribution of Cx43 was evaluated by immunofluorescence confocal microscopy. The levels of Cx43 present in gap junction plaques were assessed by its insolubility in Triton X-100 and quantified by western blotting. The stability of Cx43 at the plasma membrane following incubation with oxysterols was evaluated by biotinylation of cell surface proteins. Gap junction intercellular communication was evaluated by transfer of the dye Lucifer yellow. The results obtained showed that 7-keto induces an accumulation of Cx43 at the plasma membrane and an increase in intercellular communication through gap junction. However, incubation with cholesterol or 25-OH did not lead to significant alterations on subcellular distribution of Cx43 nor in intercellular communication. Data further suggests that increased intercellular communication results from increased stability of Cx43 at the plasma membrane, presumably forming functional gap-junctions, as suggested by decreased solubility of Cx43 in 1% Triton X-100. The increased stability of Cx43 at the plasma membrane seems to be specific and not related to disruption of endocytic pathway, as demonstrated by dextran uptake. Conclusions Results demonstrate, for the first time, that 7-keto induces an increase in gap junction intercellular communication

  18. Cell-free synthesis and assembly of connexins into functional gap junction membrane channels.

    OpenAIRE

    Falk, M M; Buehler, L K; Kumar, N.M.; Gilula, N B

    1997-01-01

    Several different gap junction channel subunit isotypes, known as connexins, were synthesized in a cell-free translation system supplemented with microsomal membranes to study the mechanisms involved in gap junction channel assembly. Previous results indicated that the connexins were synthesized as membrane proteins with their relevant transmembrane topology. An integrated biochemical and biophysical analysis indicated that the connexins assembled specifically with other connexin subunits. No...

  19. Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

    Directory of Open Access Journals (Sweden)

    Cyrill Géraud

    Full Text Available Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ, i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis.

  20. Analysis of a four lamp flash system for calibrating multi-junction solar cells under concentrated light

    International Nuclear Information System (INIS)

    It has been known for a long time that the precise characterization of multi-junction solar cells demands spectrally tunable solar simulators. The calibration of innovative multi-junction solar cells for CPV applications now requires tunable solar simulators which provide high irradiation levels. This paper describes the commissioning and calibration of a flash-based four-lamp simulator to be used for the measurement of multi-junction solar cells with up to four subcells under concentrated light

  1. Gap junctions in hematopoietic stroma control proliferation and differentiation of blood cell precursors

    Directory of Open Access Journals (Sweden)

    Bodi Estevão

    2004-01-01

    Full Text Available We examined gap junction communication in an in vitro model of hematopoiesis, using the murine bone marrow stroma cell line S-17, and primary cultures of murine marrow-derived blood cell precursors. S-17 cells express several connexins, the major one being connexin 43. Connexin expression and formation of functional gap junctions is modulated by stroma cell density. Transfection of S-17 cells with a vector containing connexin 43 sense or anti-sense sequences increased or decreased, respectively, connexin 43 synthesis and intercellular dye coupling. Under these conditions, modulation of gap junction-mediated communication modified the growth pattern of stroma itself, as well as the ability of the stroma to sustain hematopoiesis. Increased connexin 43 expression was associated with a delay in differentiation of blood cells, resulting in increased production of hematopoietic precursors, while decreased connexin 43 expression elicited an accelerated differentiation of myeloid blood cell precursor cells. These results suggest that connexin-mediated coupling in the stroma modulates the ratio between proliferation and differentiation of hematopoietic precursors. We therefore propose that increased gap junction communication in the stroma elicits an enhanced production of immature bone marrow cells through the delay in their terminal differentiation, inducing consequently an extended proliferation period of blood cell precursors.

  2. Connexin 26-mediated gap junctional intercellular communication suppresses paracellular permeability of human intestinal epithelial cell monolayers

    International Nuclear Information System (INIS)

    In some cell types, gap junctional intercellular communication (GJIC) is associated with tight junctions. The present study was performed to determine the roles of GJIC in regulation of the barrier function of tight junctions. Caco-2 human colonic cells were used as a monolayer model, and barrier function was monitored by measuring mannitol permeability and transepithelial electrical resistance (TER). The monolayers were chemically disrupted by treatment with oleic acid and taurocholic acid. Western blotting analyses were performed to evaluate the protein levels of connexins, which are components of gap junctional intercellular channels. Cx26 expression was detected in preconfluent Caco-2 cells, and its level increased gradually after the monolayer reached confluency. These results prompted us to examine whether overexpression of Cx26 affects barrier function. Monolayers of Caco-2 cells stably expressing Cx26 showed significantly lower mannitol permeability and higher TER than mock transfectants when the monolayers were chemically disrupted. The levels of claudin-4, an important component of tight junctions, were significantly increased in the stable Cx26 transfectant. These results suggest that Cx26-mediated GJIC may play a crucial role in enhancing the barrier function of Caco-2 cell monolayers

  3. Gap-Junctional Single-Channel Permeability for Fluorescent Tracers in Mammalian Cell Cultures

    OpenAIRE

    Eckert, Reiner

    2006-01-01

    We have developed a simple dye transfer method that allows quantification of the gap-junction permeability of small cultured cells. Fluorescent dyes (calcein and Lucifer yellow) were perfused into one cell of an isolated cell pair using a patch-type micropipette in the tight-seal whole cell configuration. Dye spreading into the neighboring cells was monitored using a low-light charge-coupled device camera. Permeation rates for calcein and Lucifer yellow were then estimated by fitting the time...

  4. Estimation of the junctional resistance between electrically coupled receptor cells in Necturus taste buds

    OpenAIRE

    1995-01-01

    Junctional resistance between coupled receptor cells in Necturus taste buds was estimated by modeling the results from single patch pipette voltage clamp studies on lingual slices. The membrane capacitance and input resistance of coupled taste receptor cells were measured to monitor electrical coupling and the results compared with those calculated by a simple model of electrically coupled taste cells. Coupled receptor cells were modeled by two identical receptor cells connected via a junctio...

  5. Light-splitting photovoltaic system utilizing two dual-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Kanglin; Yang, Hui [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Suzhou (China); Institute of Semiconductors, CAS, Beijing (China); Lu, Shulong; Dong, Jianrong; Zhou, Taofei; Wang, Rongxin [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Suzhou (China); Jiang, Desheng [Institute of Semiconductors, CAS, Beijing (China)

    2010-12-15

    There are many difficulties limiting the further development of monolithic multi-junction solar cells, such as the growth of lattice-mismatched material and the current matching constraint. As an alternative approach, the light-splitting photovoltaic system is investigated intensively in different aspects, including the energy loss mechanism and the choice of energy bandgaps of solar cells. Based on the investigation, a two-dual junction system has been implemented employing lattice-matched GaInP/GaAs and InGaAsP/InGaAs cells grown epitaxially on GaAs and InP substrates, respectively. (author)

  6. Saltatory formation, sliding and dissolution of ER–PM junctions in migrating cancer cells

    OpenAIRE

    Dingsdale, Hayley; Okeke, Emmanuel; Awais, Muhammad; Haynes, Lee; Criddle, David N.; Sutton, Robert; Tepikin, Alexei V.

    2013-01-01

    We demonstrated three novel forms of dynamic behaviour of junctions between the ER (endoplasmic reticulum) and the PM (plasma membrane) in migrating cancer cells: saltatory formation, long-distance sliding and dissolution. The individual ER–PM junctions formed near the leading edge of migrating cells (usually within 0.5 μm of polymerized actin and close to focal adhesions) and appeared suddenly without sliding from the interior of the cell. The long distance sliding and dissolution of ER–PM j...

  7. NREL, CSEM Jointly Set New Efficiency Record with Dual-Junction Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    2016-01-01

    Scientists set a new world record for converting non-concentrated sunlight into electricity using a dual-junction III-V/Si solar cell. National Renewable Energy Laboratory (NREL) and Swiss Center for Electronics and Microtechnology (CSEM) scientists have collaborated to create a novel tandem solar cell that operates at 29.8% conversion efficiency under non-concentrator (1-sun) conditions. In comparison, the 1-sun efficiency of a silicon (Si) single-junction solar cell is probably still a few years away from converging on its practical limit of about 26%.

  8. A functional assay for gap junctional examination; electroporation of adherent cells on indium-tin oxide.

    Science.gov (United States)

    Geletu, Mulu; Guy, Stephanie; Firth, Kevin; Raptis, Leda

    2014-01-01

    In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. A variety of molecules, such as peptides or oligonucleotides can be introduced into essentially 100% of the cells in a non-traumatic manner. Here, we describe how it can be used to study intercellular, gap junctional communication. Lucifer yellow penetrates into the cells when an electric pulse, applied to the conductive surface on which they are growing, causes pores to form through the cell membrane. This is electroporation. Cells growing on the nonconductive glass surface immediately adjacent to the electroporated region do not take up Lucifer yellow by electroporation but do acquire the fluorescent dye as it is passed to them via gap junctions that link them to the electroporated cells. The results of the transfer of dye from cell to cell can be observed microscopically under fluorescence illumination. This technique allows for precise quantitation of gap junctional communication. In addition, it can be used for the introduction of peptides or other non-permeant molecules, and the transfer of small electroporated peptides via gap junctions to inhibit the signal in the adjacent, non-electroporated cells is a powerful demonstration of signal inhibition. PMID:25350637

  9. Development of thin film space solar cells with multi-junction

    International Nuclear Information System (INIS)

    The present and future state of research and development in JAXA are introduced on the downsizing and weight reduction of solar panels. The circumstance of development, special feature and efficiency in the latest solar cells are explained. Further, its radiation resistance is shown by comparison with the three-junction solar cells used at present. (M.H.)

  10. Terrestrial silicon P-N junction solar cells obtained by ionic-implantation

    International Nuclear Information System (INIS)

    The possibilities of ionic implantation for the realization of silicon p-n junction solar-cells and essentially the properties of the thin layer doped with boron ions, the structure defects and the annealing are studied. The electrical characteristics of the cells are also reported

  11. Oxaliplatin enhances gap junction-mediated coupling in cell cultures of mouse trigeminal ganglia.

    Science.gov (United States)

    Poulsen, Jeppe Nørgaard; Warwick, Rebekah; Duroux, Meg; Hanani, Menachem; Gazerani, Parisa

    2015-08-01

    Communications between satellite glial cells and neighboring neurons within sensory ganglia may contribute to neuropathic and inflammatory pain. To elucidate the role of satellite glial cells in chemotherapy-induced pain, we examined the effects of oxaliplatin on the gap junction-mediated coupling between these cells. We also examined whether the gap junction blocker, carbenoxolone, can reverse the coupling. Primary cultures of mice trigeminal ganglia, 24-48h after cell isolation, were used. Satellite glial cells were injected with Lucifer yellow in the presence or absence of oxaliplatin (60 μM). In addition, the effect of carbenoxolone (100 μM) on coupling, and the expression of connexin 43 proteins were evaluated. Dye coupling between adjacent satellite glial cells was significantly increased (2.3-fold, P<0.05) following a 2h incubation with oxaliplatin. Adding carbenoxolone to the oxaliplatin-treated cultures reversed oxaliplatin-evoked coupling to baseline (P<0.05). Immunostaining showed no difference between expression of connexin 43 in control and oxaliplatin-treated cultures. Our findings indicated that oxaliplatin-increased gap junction-mediated coupling between satellite glial cells in primary cultures of mouse trigeminal ganglia, and carbenoxolone reversed this effect. Hence, it is proposed that increased gap junction-mediated coupling was seen between satellite glial cells in TG. This observation together with our previous data obtained from a behavioral study suggests that this phenomenon might contribute to chemotherapy-induced nociception following oxaliplatin treatment. PMID:25999145

  12. CPV module design optimization for advanced multi-junction solar cell concepts

    Science.gov (United States)

    Steiner, Marc; Kiefel, Peter; Siefer, Gerald; Wiesenfarth, Maike; Dimroth, Frank; Krause, Rainer; Gombert, Andreas; Bett, Andreas W.

    2015-09-01

    A network model for multi-junction solar cells has been combined with ray tracing and finite element simulations of a Fresnel lens in order to interpret experimentally derived measurement results. This combined model reveals a good agreement between simulation and measurement for advanced four-junction solar cells under a Fresnel lens when the cell-to-lens distance was varied. Thus, the effect of fill factor drop caused by distributed series resistance losses due to chromatic aberration is well described by this model. Eventually, this model is used to calculate I-V characteristics of a four-junction cell, as well as of a upright metamorphic and lattice-matched triple-junction solar cell under the illumination profile of a Fresnel lens. A significant fill factor drop at distinct cell-to-lens distances was found for all three investigated solar cell types. In this work we discuss how this fill factor drop can be avoided. It is shown that already a halving of the sheet resistance within one of the lateral conduction layer in the solar cell increases the module efficiency significantly.

  13. Epithelial to mesenchymal transition-The roles of cell morphology, labile adhesion and junctional coupling.

    OpenAIRE

    Abdulla, Tariq; Schleich, Jean-Marc; Summers, Ron

    2013-01-01

    International audience Epithelial to mesenchymal transition (EMT) is a fundamental process during development and disease, including development of the heart valves and tumour metastases. An extended cellular Potts model was implemented to represent the behaviour emerging from autonomous cell morphology, labile adhesion, junctional coupling and cell motility. Computer simulations normally focus on these functional changes independently whereas this model facilitates exploration of the inte...

  14. The p recombination layer in tunnel junctions for micromorph tandem solar cells

    Science.gov (United States)

    Yao, Wen-Jie; Zeng, Xiang-Bo; Peng, Wen-Bo; Liu, Shi-Yong; Xie, Xiao-Bing; Wang, Chao; Liao, Xian-Bo

    2011-07-01

    A new tunnel recombination junction is fabricated for n—i—p type micromorph tandem solar cells. We insert a thin heavily doped hydrogenated amorphous silicon (a-Si:H) p+ recombination layer between the n a-Si:H and the p hydrogenated nanocrystalline silicon (nc-Si:H) layers to improve the performance of the n—i—p tandem solar cells. The effects of the boron doping gas ratio and the deposition time of the p-a-Si:H recombination layer on the tunnel recombination junctions have been investigated. The current-voltage characteristic of the tunnel recombination junction shows a nearly ohmic characteristic, and the resistance of the tunnel recombination junction can be as low as 1.5 Ω·cm2 by using the optimized p-a-Si:H recombination layer. We obtain tandem solar cells with open circuit voltage Voc = 1.4 V, which is nearly the sum of the Vocs of the two corresponding single cells, indicating no Voc losses at the tunnel recombination junction.

  15. Gap junctions between CA3 pyramidal cells contribute to network synchronization in neonatal hippocampus.

    Science.gov (United States)

    Molchanova, Svetlana M; Huupponen, Johanna; Lauri, Sari E; Taira, Tomi

    2016-08-01

    Direct electrical coupling between neurons through gap junctions is prominent during development, when synaptic connectivity is scarce, providing the additional intercellular connectivity. However, functional studies of gap junctions are hampered by the unspecificity of pharmacological tools available. Here we have investigated gap-junctional coupling between CA3 pyramidal cells in neonatal hippocampus and its contribution to early network activity. Four different gap junction inhibitors, including the general blocker carbenoxolone, decreased the frequency of network activity bursts in CA3 area of hippocampus of P3-6 rats, suggesting the involvement of electrical connections in the generation of spontaneous network activity. In CA3 pyramidal cells, spikelets evoked by local stimulation of stratum oriens, were inhibited by carbenoxolone, but not by inhibitors of glutamatergic and GABAergic synaptic transmission, signifying the presence of electrical connectivity through axo-axonic gap junctions. Carbenoxolone also decreased the success rate of firing antidromic action potentials in response to stimulation, and changed the pattern of spontaneous action potential firing of CA3 pyramidal cells. Altogether, these data suggest that electrical coupling of CA3 pyramidal cells contribute to the generation of the early network events in neonatal hippocampus by modulating their firing pattern and synchronization. PMID:26926429

  16. The photoelectric characteristics of a few-layer graphene/Si Schottky junction solar cell

    Science.gov (United States)

    Ma, Xiying; Gu, Weixia

    2015-10-01

    We present a study of the photovoltaic effects of a graphene/n- Si Schottky junction solar cell. The graphene/Si solar cell was prepared by means of rapid chemical vapor deposition, while the graphene films were grown with a CH4/Ar mixed gas under a constant flow at 950°C and then annealed at 1000°C. It was found that the junction between the graphene film and the n-Si structure played an important role in determining the device performance. An energy conversion efficiency of 2.1% was achieved under an optical illumination of 100 mW. The strong photovoltaic effects of the cell were due to device junction's ability to efficiently generate and separate electron-hole pairs.

  17. Increased efficiency in multijunction solar cells through the incorporation of semimetallic ErAs nanoparticles into the tunnel junction

    International Nuclear Information System (INIS)

    We report the molecular beam epitaxy growth of Al0.3Ga0.7As/GaAs multijunction solar cells with epitaxial, semimetallic ErAs nanoparticles at the interface of the tunnel junction. The states provided by these nanoparticles reduce the bias required to pass current through the tunnel junction by three orders of magnitude, and therefore drastically reduce the voltage losses in the tunnel junction. We have measured open-circuit voltages which are 97% of the sum of the constituent cells, which result in nearly double the efficiency of our multijunction cell with a conventional tunnel junction

  18. Detailed Analysis of Temperature Characteristics of an InGaP/InGaAs/Ge Triple-Junction Solar Cell

    Science.gov (United States)

    Nishioka, Kensuke; Sueto, Tsuyoshi; Uchida, Masaki; Ota, Yasuyuki

    2010-06-01

    Temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell were analyzed in detail using an equivalent circuit calculation. The current-voltage ( I- V) characteristics of single-junction solar cells (InGaP, InGaAs, Ge solar cells) were measured at various temperatures. Fitting of I- V curves between measured and calculated data was carried out, and the diode parameters and temperature exponents of the single-junction solar cells were extracted. The parameters for each single-junction solar cell were used in the equivalent circuit model for the triple-junction solar cell, and calculations of solar cell performance were carried out. Measured and calculated results of the I- V characteristics at various temperatures agreed well.

  19. Connexin36 is Required for Gap Junctional Coupling of Most Ganglion Cell Subtypes in the Mouse Retina

    OpenAIRE

    Pan, Feng; Paul, David L.; Bloomfield, Stewart A.; Völgyi, Béla

    2010-01-01

    Converging evidence indicates that electrical synaptic transmission via gap junctions plays a crucial role in signal processing in the retina. In particular, amacrine and ganglion cells express numerous gap junctions, resulting in extensive electrical networks in the proximal retina. Both connexin36 (Cx36) and connexin45 (Cx45) subunits are widely distributed in the inner plexiform layer (IPL) and therefore are likely contribute to gap junctions formed by a number of ganglion cell subtypes. I...

  20. Correlation of interfacial bonding mechanism and equilibrium conductance of molecular junctions

    OpenAIRE

    Ning, Zhanyu; Qiao, Jingsi; Ji, Wei; Guo, Hong

    2009-01-01

    We report theoretical investigations on the role of interfacial bonding mechanism and its resulting structures to quantum transport in molecular wires. Two bonding mechanisms for the Au-S bond in an Au(111)/1,4-benzenedithiol(BDT)/Au(111) junction were identified by ab initio calculation, confirmed by a recent experiment, which, we showed, critically control charge conduction. It was found, for Au/ BDT/Au junctions, the hydrogen atom, bound by a dative bond to the Sulfur, is energetically non...

  1. Hydrogenated Amorphous Silicon Germanium Active Layer for Top Cell of a Multi Junction Cell Structure.

    Science.gov (United States)

    Cho, Jaehyun; Iftiquar, S M; Kim, Minbum; Park, Jinjoo; Jung, Junhee; Kim, Jiwoong; Yi, Junsin

    2016-05-01

    Intrinsic hydrogenated amorphous silicon-germanium (a-SiGe:H) alloy is generally used in the bottom cell because of its low band gap. The a-SiGe:H has a higher photo conductivity in comparison to the a-Si:H; thus, it is expected that the a-SiGe:H can show better short circuit current density than that of the a-Si:H based solar cell. Therefore, we optimized a-SiGe:H active layer that can be a suitable choice for the front cell of a multi junction.solar cell. Furthermore, we carried out a comparative study of the solar cells that have a-SiGe:H and a-Si:H as respective active layers. The a-SiGe:H based solar cells show higher short circuit current density, while the a-Si:H based cells show higheropen circuit voltage. The current-voltage characteristics of these cells are as follows: (a) V(oc) = 770 mV, J(sc) = 15.0 mA/cm2, FF = 64.5%, and η = 7.47% for a-SiGe:H based cell; and (b) V(oc) = 826 mV, J(sc) = 13.63 mA/cm2, FF = 72.0%, and η = 8.1% for a-Si:H based cell. PMID:27483837

  2. Glycoproteins of coated pits, cell junctions, and the entire cell surface revealed by monoclonal antibodies and immunoelectron microscopy

    OpenAIRE

    1983-01-01

    Topographical descriptions of three major plasma membrane glycoproteins of murine 3T3 cells were obtained by immunoelectron microscopy with monoclonal antibodies. A glycoprotein of Mr 80,000 was distributed throughout the total cell surface. A second of Mr 90,000 was concentrated in coated pits, and a third of Mr 100,000 was localized at cell junctions.

  3. Gap junctions in cells of the immune system: structure, regulation and possible functional roles

    Directory of Open Access Journals (Sweden)

    J.C. Sáez

    2000-04-01

    Full Text Available Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system.

  4. Estimation of the effective intercellular diffusion coefficient in cell monolayers coupled by gap junctions

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Hofgaard, Johannes P; von Holstein-Rathlou, Niels-Henrik;

    2012-01-01

    A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non-electropo......A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non...

  5. A GaAs/GaInP dual junction solar cell grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    We report the recent result of GaAs/GaInP dual-junction solar cells grown by all solid-state molecular-beam-epitaxy (MBE). The device structure consists of a GaIn0.48P homojunction grown epitaxially upon a GaAs homojunction, with an interconnected GaAs tunnel junction. A photovoltaic conversion efficiency of 27% under the AM1.5 globe light intensity is realized for a GaAs/GaInP dual-junction solar cell, while the efficiencies of 26% and 16.6% are reached for a GaAs bottom cell and a GaInP top cell, respectively. The energy loss mechanism of our GaAs/GaInP tandem dual-junction solar cells is discussed. It is demonstrated that the MBE-grown phosphide-containing III—V compound semiconductor solar cell is very promising for achieving high energy conversion efficiency. (semiconductor devices)

  6. Mathematical modeling of gap junction coupling and electrical activity in human β-cells

    Science.gov (United States)

    Loppini, Alessandro; Braun, Matthias; Filippi, Simonetta; Gram Pedersen, Morten

    2015-12-01

    Coordinated insulin secretion is controlled by electrical coupling of pancreatic β-cells due to connexin-36 gap junctions. Gap junction coupling not only synchronizes the heterogeneous β-cell population, but can also modify the electrical behavior of the cells. These phenomena have been widely studied with mathematical models based on data from mouse β-cells. However, it is now known that human β-cell electrophysiology shows important differences to its rodent counterpart, and although human pancreatic islets express connexin-36 and show evidence of β-cell coupling, these aspects have been little investigated in human β-cells. Here we investigate theoretically, the gap junction coupling strength required for synchronizing electrical activity in a small cluster of cells simulated with a recent mathematical model of human β-cell electrophysiology. We find a lower limit for the coupling strength of approximately 20 pS (i.e., normalized to cell size, ˜2 pS pF-1) below which spiking electrical activity is asynchronous. To confront this theoretical lower bound with data, we use our model to estimate from an experimental patch clamp recording that the coupling strength is approximately 100-200 pS (10-20 pS pF-1), similar to previous estimates in mouse β-cells. We then investigate the role of gap junction coupling in synchronizing and modifying other forms of electrical activity in human β-cell clusters. We find that electrical coupling can prolong the period of rapid bursting electrical activity, and synchronize metabolically driven slow bursting, in particular when the metabolic oscillators are in phase. Our results show that realistic coupling conductances are sufficient to promote synchrony in small clusters of human β-cells as observed experimentally, and provide motivation for further detailed studies of electrical coupling in human pancreatic islets.

  7. Microelectrical characterizations of junctions in solar cell devices by scanning Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Scanning Kelvin probe force microscopy was applied to the microelectrical characterizations of junctions in solar cell devices. Surface Fermi-level pinning effects on the surface potential measurement were avoided by applying a bias voltage (Vb) to the device and taking the Vb-induced potential and electric field changes. Two characterizations are presented: the first is a direct measurement of Bi-induced junction shift in GaInNAs(Bi) cells; the second is a junction-uniformity measurement in a-Si:H devices. In the first characterization, using Bi as a surfactant during the molecular beam epitaxy growth of GaInNAs(Bi) makes the epitaxial layer smoother. However, the electrical potential measurement exhibits a clear Bi-induced junction shift to the back side of the absorber layer, which results in significant device degradation. In the second characterization, the potential measurement reveals highly non-uniform electric field distributions across the n-i-p junction of a-Si:H devices; the electric field concentrates much more at both n/i and i/p interfaces than in the middle of the i-layer. This non-uniform electric field is due possibly to high defect concentrations at the interfaces. The potential measurements further showed a significant improvement in the electric field uniformity by depositing buffer layers at the interfaces, and this indeed improved the device performance.

  8. Incidence angle and spectral effects on vertical junction silicon solar cell capacitance

    OpenAIRE

    SANE, MOUSTAPHA; ŞAHİN, Gökhan; BARRO, Fabé Idrissa; MAIGA, Amadou Seidou

    2014-01-01

    The aim of this work is to present a theoretical study of a vertical junction silicon solar cell under monochromatic illumination. By solving the continuity equation and using a one-dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both illumination wavelength and incidence angle on the solar cell capaci...

  9. Model for synchronization of pancreatic beta-cells by gap junction coupling.

    OpenAIRE

    Sherman, A.; Rinzel, J

    1991-01-01

    Pancreatic beta-cells coupled by gap junctions in sufficiently large clusters exhibit regular electrical bursting activity, which is described by the Chay-Keizer model and its variants. According to most reports, however, isolated cells exhibit disorganized spiking. We have previously (Sherman, A. J. Rinzel, and J. Keizer, 1988. Biophys. J. 54:411-425) modeled these behaviors by hypothesizing that stochastic channel fluctuations disrupt the bursts. We showed that when cells are coupled by inf...

  10. Theoretical efficiency limit for a two-terminal multi-junction "step-cell" using detailed balance method

    Science.gov (United States)

    Abdul Hadi, Sabina; Fitzgerald, Eugene A.; Nayfeh, Ammar

    2016-02-01

    Here we present detailed balance efficiency limit for a novel two-terminal dual and triple junction "step-cell" under AM 1.5G and AM 0 incident spectrums. The step-cell is a multi-junction (MJ) solar cell in which part of the top cell is removed, exposing some of the bottom cell area to unfiltered incident light, thus increasing bottom cell's photogenerated current. Optical generation of the bottom cell is modeled in two parts: step part, limited by the bottom cell bandgap, and conventional part, additionally limited by the top cell absorption. Our results show that conventionally designed MJ cell with optimized bandgap combination of 1.64 eV/0.96 eV for dual junction and 1.91 eV/1.37 eV/0.93 eV for triple junction has the highest theoretical efficiency limit. However, the step-cell design provides significant efficiency improvement for cells with non-optimum bandgap values. For example, for 1.41 eV ( ˜GaAs)/Si dual junction under AM 1.5G, efficiency limit increases from ˜21% in a conventional design to 38.7% for optimized step-cell. Similar benefits are observed for three-junction step-cell and for AM 0 spectrum studied here. Step-cell relaxes bandgap requirements for efficient MJ solar cells, providing an opportunity for a wider selection of materials and cost reduction.

  11. Pseudomonas aeruginosa Transmigrates at Epithelial Cell-Cell Junctions, Exploiting Sites of Cell Division and Senescent Cell Extrusion.

    Directory of Open Access Journals (Sweden)

    Guillaume Golovkine

    2016-01-01

    Full Text Available To achieve systemic infection, bacterial pathogens must overcome the critical and challenging step of transmigration across epithelial barriers. This is particularly true for opportunistic pathogens such as Pseudomonas aeruginosa, an agent which causes nosocomial infections. Despite extensive study, details on the mechanisms used by this bacterium to transmigrate across epithelial tissues, as well as the entry sites it uses, remain speculative. Here, using real-time microscopy and a model epithelial barrier, we show that P. aeruginosa employs a paracellular transmigration route, taking advantage of altered cell-cell junctions at sites of cell division or when senescent cells are expelled from the cell layer. Once a bacterium transmigrates, it is followed by a cohort of bacteria using the same entry point. The basal compartment is then invaded radially from the initial penetration site. Effective transmigration and propagation require type 4 pili, the type 3 secretion system (T3SS and a flagellum, although flagellum-deficient bacteria can occasionally invade the basal compartment from wounded areas. In the basal compartment, the bacteria inject the T3SS toxins into host cells, disrupting the cytoskeleton and focal contacts to allow their progression under the cells. Thus, P. aeruginosa exploits intrinsic host cell processes to breach the epithelium and invade the subcellular compartment.

  12. Sensitive thermal microsensor with pn junction for heat measurement of a single cell

    Science.gov (United States)

    Yamada, Taito; Inomata, Naoki; Ono, Takahito

    2016-02-01

    A sensitive thermal microsensor based on a pn junction diode for heat measurements of biological single cells is developed and evaluated. Using a fabricated device, we demonstrated the heat measurement of a single brown fat cell. The principle of the sensor relies on the temperature dependence of the pn junction diode resistance. This method has a capability of the highly thermal sensitivity by downsizing and the advantage of a simple experimental setup using electrical circuits without any special equipment. To achieve highly sensitive heat measurement of single cells, downsizing of the sensor is necessary to reduce the heat capacity of the sensor itself. The sensor with the pn junction diode can be downsized by microfabrication. A bridge beam structure with the pn junction diode as a thermal sensor is placed in vacuum using a microfludic chip to decrease the heat loss to the surroundings. A temperature coefficient of resistance of 1.4%/K was achieved. The temperature and thermal resolutions of the fabricated device are 1.1 mK and 73.6 nW, respectively. The heat measurements of norepinephrine stimulated and nonstimulated single brown fat cells were demonstrated, and different behaviors in heat generation were observed.

  13. Fluctuations of the peak current of tunnel diodes in multi-junction solar cells

    International Nuclear Information System (INIS)

    Interband tunnel diodes are widely used to electrically interconnect the individual subcells in multi-junction solar cells. Tunnel diodes have to operate at high current densities and low voltages, especially when used in concentrator solar cells. They represent one of the most critical elements of multi-junction solar cells and the fluctuations of the peak current in the diodes have an essential impact on the performance and reliability of the devices. Recently we have found that GaAs tunnel diodes exhibit extremely high peak currents that can be explained by resonant tunnelling through defects homogeneously distributed in the junction. Experiments evidence rather large fluctuations of the peak current in the diodes fabricated from the same wafer. It is a challenging task to clarify the reason for such large fluctuations in order to improve the performance of the multi-junction solar cells. In this work we show that the large fluctuations of the peak current in tunnel diodes can be caused by relatively small fluctuations of the dopant concentration. We also show that the fluctuations of the peak current become smaller for deeper energy levels of the defects responsible for the resonant tunnelling.

  14. Simulation and optimization of current matching double-junction InGaN/Si solar cells

    Science.gov (United States)

    Nacer, S.; Aissat, A.

    2016-02-01

    This paper deals with theoretical investigation of the performance of current-matched In x GaN/Si double-junction solar cells. Calculations were performed under 1-sun AM1.5 using the one diode ideal model. Impact of minor carrier lifetime and surface recombination velocity in the top sub-cell on the cell performances is analyzed. Optimum composition of the top sub-cell has been identified ( x = 51.8 % and E g = 1.68 eV). The simulation results predict, for the optimized InGaN/Si double-junction solar cell, a short-circuit current J sc = 20 mA/cm2, an open-circuit voltage V oc = 1.97 V, and a conversion efficiency η = 38.3%.

  15. Epithelial to mesenchymal transition-the roles of cell morphology, labile adhesion and junctional coupling.

    Science.gov (United States)

    Abdulla, Tariq; Luna-Zurita, Luis; de la Pompa, José Luis; Schleich, Jean-Marc; Summers, Ron

    2013-08-01

    Epithelial to mesenchymal transition (EMT) is a fundamental process during development and disease, including development of the heart valves and tumour metastases. An extended cellular Potts model was implemented to represent the behaviour emerging from autonomous cell morphology, labile adhesion, junctional coupling and cell motility. Computer simulations normally focus on these functional changes independently whereas this model facilitates exploration of the interplay between cell shape changes, adhesion and migration. The simulation model is fitted to an in vitro model of endocardial EMT, and agrees with the finding that Notch signalling increases cell-matrix adhesion in addition to modulating cell-cell adhesion. PMID:23787029

  16. The distribution of interstitial cells of Cajal in congenital ureteropelvic junction obstruction

    OpenAIRE

    Apoznanski, Wojciech; Koleda, Piotr; Wozniak, Zdzislaw; Rusiecki, Leslaw; Szydelko, Tomasz; Kalka, Dariusz; Pilecki, Witold

    2013-01-01

    Purpose The authors analysed the distribution of c-kit-positive interstitial cells of Cajal (ICCs) in obstructed ureteropelvic junction (UPJ) and its age-related changes. Methods Twenty specimens were obtained from children with intrinsic ureteropelvic junction obstruction (UPJO), at the average age of 8.1 years (8 months–16.8 years), fixed in formalin and embedded in paraffin. Five control samples were taken from children at the average age of 2.3 years (2.4 months–7.4 years). All specimens ...

  17. An ARC less InGaP/GaAs DJ solar cell with hetero tunnel junction

    Science.gov (United States)

    Sahoo, G. S.; Nayak, P. P.; Mishra, G. P.

    2016-07-01

    Multi junction solar cell has not achieved an optimum performance yet. To acquire more conversion efficiency research on multi junction solar cell are in progress. In this work we have proposed a dual junction solar cell with conversion efficiency of 43.603%. Mainly the focus is given on the tunnel diode, window layer and back surface field (BSF) layer of the cell, as all of them plays important role on the cell performance. Here we have designed a hetero InGaP/GaAs tunnel diode which makes tunnel diode more transparent to the bottom cell as well as reduces the recombination at the interfaces. The thickness of the window and BSF layer are optimized to achieve higher conversion efficiency. The simulation is carried out using Silvaco ATLAS TCAD under 1000 sun of AM1.5G spectrum. Different performance parameters of the cell like short circuit current density (Jsc), open circuit voltage (Voc), external quantum efficiency (EQE), fill factor (FF), conversion efficiency (η), spectral response and photogeneration rate of the cell are examined and compared with previously reported literatures. For the proposed model a Voc of 2.7043 V, Jsc of 1898.52 mA/cm2, FF of 88.88% and η of 43.6% are obtained.

  18. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate

    Science.gov (United States)

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-01-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination. PMID:27435899

  19. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate.

    Science.gov (United States)

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-01-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination. PMID:27435899

  20. Guidelines for the Bandgap Combinations and Absorption Windows for Organic Tandem and Triple-Junction Solar Cells

    OpenAIRE

    Ben Minnaert; Peter Veelaert

    2012-01-01

    Organic solar cells have narrow absorption windows, compared to the absorption band of inorganic semiconductors. A possible way to capture a wider band of the solar spectrum-and thus increasing the power conversion efficiency-is using more solar cells with different bandgaps in a row, i.e., a multi-junction solar cell. We calculate the ideal material characteristics (bandgap combinations and absorption windows) for an organic tandem and triple-junction solar cell, as well as their acceptable ...

  1. Modulation of human cell responses to space radiation by gap-junction communication

    Science.gov (United States)

    Autsavapromporn, Narongchai; de Toledo, Sonia M.; Buonanno, Manuela; Yang, Zhi; Harris, Andrew; Jay-Gerin, Jean-Paul; Azzam, Edouard

    Understanding the biological effects of space radiation and their underlying mechanism is critical to estimating the health risk associated with human exploration of space. A coordinated interaction of multiple cellular processes is likely involved in the sensing and processing of stressful effects induced by different types of space radiation. Here, we focused on the role of gap-junction intercellular communication (GJIC) in responses of human cells exposed to 1 GeV/n protons or 56 Fe-ions. We compared the results with data obtained in human cells exposed, in parallel, to γ-rays or α-particles. As expected, a higher level of cell killing and DNA damage, per unit dose, was induced in confluent, density-inhibited cells (98% in G0 /G1 ) exposed to α-particles or energetic 56 Fe-ions than γ-rays or protons. Strikingly, greatly attenuated effects occurred when sub-confluent cultures, synchronized in G0 /G1 ,were exposed to 56 Fe-ions. These data suggest that direct intercellular communication is involved in the effects of high linear energy transfer (LET) 56 Fe-ions. To examine the role of gap-junctions in propagating stressful effect, confluent cultures were exposed to 56 Fe-ions or α-particles and incubated for various time periods at 37° C in the presence or absence of the gap-junction inhibitor α-glycyrrhetinic acid (AGA). No repair of potentially lethal radiation damage occurred in cells incubated in the absence of AGA. In contrast, inhibition of functional GJIC significantly enhanced clonogenic survival of irradiated cells. To test the role of junctional channel permeability in the observed effects, we used human adenocarcinoma (HeLa) cells in which specific connexins (Cx) can be expressed in the absence of endogenous connexins. Whereas HeLa cells with selective inducible expression of Cx26 gap-junctions promoted radiation toxic effects, expression of Cx32 junctional channels in HeLa cells promoted pro-survival effects. Experiments are in progress to

  2. Real-time imaging of endothelial cell-cell junctions during neutrophil transmigration under physiological flow.

    Science.gov (United States)

    Kroon, Jeffrey; Daniel, Anna E; Hoogenboezem, Mark; van Buul, Jaap D

    2014-01-01

    During inflammation, leukocytes leave the circulation and cross the endothelium to fight invading pathogens in underlying tissues. This process is known as leukocyte transendothelial migration. Two routes for leukocytes to cross the endothelial monolayer have been described: the paracellular route, i.e., through the cell-cell junctions and the transcellular route, i.e., through the endothelial cell body. However, it has been technically difficult to discriminate between the para- and transcellular route. We developed a simple in vitro assay to study the distribution of endogenous VE-cadherin and PECAM-1 during neutrophil transendothelial migration under physiological flow conditions. Prior to neutrophil perfusion, endothelial cells were briefly treated with fluorescently-labeled antibodies against VE-cadherin and PECAM-1. These antibodies did not interfere with the function of both proteins, as was determined by electrical cell-substrate impedance sensing and FRAP measurements. Using this assay, we were able to follow the distribution of endogenous VE-cadherin and PECAM-1 during transendothelial migration under flow conditions and discriminate between the para- and transcellular migration routes of the leukocytes across the endothelium. PMID:25146919

  3. Adherens junction distribution mechanisms during cell-cell contact elongation in Drosophila.

    Directory of Open Access Journals (Sweden)

    Gabrielle Goldenberg

    Full Text Available During Drosophila gastrulation, amnioserosa (AS cells flatten and spread as an epithelial sheet. We used AS morphogenesis as a model to investigate how adherens junctions (AJs distribute along elongating cell-cell contacts in vivo. As the contacts elongated, total AJ protein levels increased along their length. However, genetically blocking this AJ addition indicated that it was not essential for maintaining AJ continuity. Implicating other remodeling mechanisms, AJ photobleaching revealed non-directional lateral mobility of AJs along the elongating contacts, as well as local AJ removal from the membranes. Actin stabilization with jasplakinolide reduced AJ redistribution, and live imaging of myosin II along elongating contacts revealed fragmented, expanding and contracting actomyosin networks, suggesting a mechanism for lateral AJ mobility. Actin stabilization also increased total AJ levels, suggesting an inhibition of AJ removal. Implicating AJ removal by endocytosis, clathrin endocytic machinery accumulated at AJs. However, dynamin disruption had no apparent effect on AJs, suggesting the involvement of redundant or dynamin-independent mechanisms. Overall, we propose that new synthesis, lateral diffusion, and endocytosis play overlapping roles to populate elongating cell-cell contacts with evenly distributed AJs in this in vivo system.

  4. Fabrication of solution-processed hydrogenated amorphous silicon single junction solar cells

    OpenAIRE

    Masuda, Takashi; Sotani, Naoya; Hamada, Hiroki; Matsuki, Yasuo; Shimoda, Tatsuya

    2012-01-01

    Hydrogenated amorphous silicon solar cells were fabricated using solution-based processes. All silicon layers of the p-i-n junction were stacked by a spin-cast method using doped and non-doped polydihydrosilane solutions. Further, a hydrogen-radical treatment under vacuum conditions was employed to reduce spin density in the silicon films. Following this treatment, the electric properties of the silicon films were improved, and the power conversion efficiency of the solar cells was also incre...

  5. Porous copper zinc tin sulfide thin film as photocathode for double junction photoelectrochemical solar cells.

    Science.gov (United States)

    Dai, Pengcheng; Zhang, Guan; Chen, Yuncheng; Jiang, Hechun; Feng, Zhenyu; Lin, Zhaojun; Zhan, Jinhua

    2012-03-21

    Porous copper zinc tin sulfide (CZTS) thin film was prepared via a solvothermal approach. Compared with conventional dye-sensitized solar cells (DSSCs), double junction photoelectrochemical cells using dye-sensitized n-type TiO(2) (DS-TiO(2)) as the photoanode and porous p-type CZTS film as the photocathode shows an increased short circuit current, external quantum efficiency and power conversion efficiency. PMID:22322239

  6. Intraplate seismicity in the western Bohemian Massif (central Europe): A possible correlation with a paleoplate junction

    Czech Academy of Sciences Publication Activity Database

    Babuška, Vladislav; Plomerová, Jaroslava; Fischer, Tomáš

    2007-01-01

    Roč. 44, č. 3-5 (2007), s. 149-159. ISSN 0264-3707 R&D Projects: GA ČR GA205/04/0748; GA ČR(CZ) GA205/06/1780; GA ČR GA205/07/1088 Institutional research plan: CEZ:AV0Z30120515 Keywords : Bohemian Massif * junction of paleoplates * intraplate earthquake swarms * brittle-ductile transition Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.321, year: 2007

  7. Novel pharmacologic targeting of tight junctions and focal adhesions in prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Patrick J Hensley

    Full Text Available Cancer cell resistance to anoikis driven by aberrant signaling sustained by the tumor microenvironment confers high invasive potential and therapeutic resistance. We recently generated a novel lead quinazoline-based Doxazosin® derivative, DZ-50, which impairs tumor growth and metastasis via anoikis. Genome-wide analysis in the human prostate cancer cell line DU-145 identified primary downregulated targets of DZ-50, including genes involved in focal adhesion integrity (fibronectin, integrin-α6 and talin, tight junction formation (claudin-11 as well as insulin growth factor binding protein 3 (IGFBP-3 and the angiogenesis modulator thrombospondin 1 (TSP-1. Confocal microscopy demonstrated structural disruption of both focal adhesions and tight junctions by the downregulation of these gene targets, resulting in decreased cell survival, migration and adhesion to extracellular matrix (ECM components in two androgen-independent human prostate cancer cell lines, PC-3 and DU-145. Stabilization of cell-ECM interactions by overexpression of talin-1 and/or exposing cells to a fibronectin-rich environment mitigated the effect of DZ-50. Loss of expression of the intracellular focal adhesion signaling effectors talin-1 and integrin linked kinase (ILK sensitized human prostate cancer to anoikis. Our findings suggest that DZ-50 exerts its antitumor effect by targeting the key functional intercellular interactions, focal adhesions and tight junctions, supporting the therapeutic significance of this agent for the treatment of advanced prostate cancer.

  8. Effects of adenine nucleotide and sterol depletion on tight junction structure and function in MDCK cells

    International Nuclear Information System (INIS)

    The antitumor agent Hadacidin (H), N-formyl-hydroxyamino-acetic acid, reversibly inhibited the multiplication of clone 4 Madin-Darby canine kidney (MDCK) cells at a 4 mM concentration within 24-48 hours. Treated cells were arrested in the S phase of the cell cycle. Accompanying this action was a 16-fold increase in the area occupied b the cells and a refractoriness to trypsin treatment. To test whether this effect was due to an increase in tight junction integrity, electrical resistance (TER) was measured across H-treated monolayers. Addition of H at the onset of junction formation reversibly prevented the development of TER. ATP and cAMP levels were decreased by H, as well as the rate of [3H]-leucine incorporation into protein. When 1 mM dibutyryl-cAMP (d.cAMP) and theophylline were added, H had no effect on cell division or protein synthesis, and TER was partially restored. The addition of 1 mM d.cAMP and 1 mM theophylline to control cultures decreased TER, indicating a biphasic effect on TER development/maintenance. In a separate study, the effect of sterol depletion on tight junctions formation/maintenance in wild-type MDCK cells was investigated

  9. Homeostatic Signaling by Cell–Cell Junctions and Its Dysregulation during Cancer Progression

    Directory of Open Access Journals (Sweden)

    Yang Yu

    2016-02-01

    Full Text Available The transition of sessile epithelial cells to a migratory, mesenchymal phenotype is essential for metazoan development and tissue repair, but this program is exploited by tumor cells in order to escape the confines of the primary organ site, evade immunosurveillance, and resist chemo-radiation. In addition, epithelial-to-mesenchymal transition (EMT confers stem-like properties that increase efficiency of colonization of distant organs. This review evaluates the role of cell–cell junctions in suppressing EMT and maintaining a quiescent epithelium. We discuss the conflicting data on junctional signaling in cancer and recent developments that resolve some of these conflicts. We focus on evidence from breast cancer, but include other organ sites where appropriate. Current and potential strategies for inhibition of EMT are discussed.

  10. Enhancing light absorption within the carrier transport length in quantum junction solar cells.

    Science.gov (United States)

    Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene

    2015-09-10

    Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31  mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells. PMID:26368966

  11. Simulation of the Efficiency of CdS/CdTe Tandem Multi-Junction Solar Cells

    CERN Document Server

    Mirkamali, Ashrafalsadat S

    2016-01-01

    In this paper we study CdS/CdTe solar cells by means of AMPS-1D software. First we study the effect of thickness of semiconductor layers on the output parameters of the CdS/CdTe solar cell, such as density of short-circuit current, open circuit voltage, fill factor and efficiency. Numerical simulation shows that the highest efficiency of single-junction CdS/CdTe solar cell equal to 18.3% is achieved when the CdTe layer thickness is 1000 nm and a CdS layer is 60 nm. Then, in order to obtain the maximal value of the efficiency, new tandem multi-junction structure consisting of layers of two solar cells connected with each other back to back are designed and engineered taking into account the results obtained for the single-junction solar cells. Numerical simulations show that its highest efficiency in 31.8% can be obtained when the thickness of CdS p-layer is equal to 50 nm, and the thickness of the CdS n-layer is equal to 200 nm, while thicknesses of the CdTe n-layer and CdTe p-layer are kept fixed and equal t...

  12. Principles of solar cells, LEDs and diodes the role of the PN junction

    CERN Document Server

    Kitai, Adrian

    2011-01-01

    The book will cover the two most important applications of semiconductor diodes - solar cells and LEDs - together with quantitative coverage of the physics of the PN junction at the senior undergraduate level. It will include: Review of semiconductor physicsIntroduction to PN diodesThe solar cellPhysics of efficient conversion of sunlight into electrical energySemiconductor solar cell materials and device physicsAdvanced solar cell materials and devicesThe light emitting diodePhysics of efficient conversion of electrical energy into lightSemiconductor li

  13. Treponema pallidum invades intercellular junctions of endothelial cell monolayers.

    OpenAIRE

    Thomas, D D; Navab, M; D.A. Haake; Fogelman, A M; Miller, J N; Lovett, M A

    1988-01-01

    The pathogenesis of syphilis reflects invasive properties of Treponema pallidum, but the actual mode of tissue invasion is unknown. We have found two in vitro parallels of treponemal invasiveness. We tested whether motile T. pallidum could invade host cells by determining the fate of radiolabeled motile organisms added to a HeLa cell monolayer; 26% of treponemes associated with the monolayer in a trypsin-resistant niche, presumably between the monolayer and the surface to which it adhered, bu...

  14. EMP-1 is a junctional protein in a liver stem cell line and in the liver

    International Nuclear Information System (INIS)

    In an attempt to discover cell markers for liver stem cells, a cDNA microarray analysis was carried out to compare the gene expression profiles between an adult liver stem cell line, Lig-8, and mature hepatocytes. Several genes in the categories of extracellular matrix, cell membrane, cell adhesion, transcription factor, signal molecule, transporter, and metabolic enzyme were shown to be differentially expressed in Lig-8 cells. Among them, epithelial membrane protein (EMP)-1 has been previously implicated with stem cell phenotypes. Antiserum to EMP-1 was produced to localize its expression. On monolayers of Lig-8 cells, EMP-1 was expressed along the intercellular border. In the liver harboring proliferating oval cells, the liver progenitors, EMP-1 was localized as ribbon bands, a staining pattern for epithelial junctions, all the way through bile duct epithelia, oval cell ductules, and into peri-hepatocytic regions. These peri-hepatocytic regions were proved to be bile canaliculi by co-localization of EMP-1 and dipeptidyl peptidase IV, an enzyme located on bile canaliculi. This report is the first to indicate EMP-1 to be a junctional protein in the liver

  15. Electrical signal transmission in a bone cell network: the influence of a discrete gap junction

    Science.gov (United States)

    Zhang, D.; Weinbaum, S.; Cowin, S. C.

    1998-01-01

    A refined electrical cable model is formulated to investigate the role of a discrete gap junction in the intracellular transmission of electrical signals in an electrically coupled system of osteocytes and osteoblasts in an osteon. The model also examines the influence of the ratio q between the membrane's electrical time constant and the characteristic time of pore fluid pressure, the circular, cylindrical geometry of the osteon, and key simplifying assumptions in our earlier continuous cable model (see Zhang, D., S. C. Cowin, and S. Weinbaum. Electrical signal transmission and gap junction regulation in a bone cell network: A cable model for an osteon. Ann. Biomed. Eng. 25:379-396, 1997). Using this refined model, it is shown that (1) the intracellular potential amplitude at the osteoblastic end of the osteonal cable retains the character of a combination of a low-pass and a high-pass filter as the corner frequency varies in the physiological range; (2) the presence of a discrete gap junction near a resting osteoblast can lead to significant modulation of the intracellular potential and current in the osteoblast for measured values of the gap junction coupling strength; and (3) the circular, cylindrical geometry of the osteon is well simulated by the beam analogy used in Zhang et al.

  16. Stokes flow paths separation and recirculation cells in X-junctions of varying angle

    CERN Document Server

    Cachile, Mario; Gomba, Juan M; Hulin, Jean-Pierre; Auradou, Harold

    2012-01-01

    Fluid and solute transfer in X-junctions between straight channels is shown to depend critically on the junction angle in the Stokes flow regime. Experimentally, water and a water-dye solution are injected at equal flow rates in two facing channels of the junction: Planar Laser Induced fluorescence (PLIF) measurements show that the largest part of each injected fluid "bounces back" preferentially into the outlet channel at the lowest angle to the injection; this is opposite to the inertial case and requires a high curvature of the corresponding streamlines. The proportion of this fluid in the other channel decreases from 50% at 90\\degree to zero at a threshold angle. These counterintuitive features reflect the minimization of energy dissipation for Stokes flows. Finite elements numerical simulations of a 2D Stokes flow of equivalent geometry con rm these results and show that, below the threshold angle 33.8\\degree recirculation cells are present in the center part of the junction and separate the two injected...

  17. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    Science.gov (United States)

    Jäckle, Sara; Mattiza, Matthias; Liebhaber, Martin; Brönstrup, Gerald; Rommel, Mathias; Lips, Klaus; Christiansen, Silke

    2015-08-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.

  18. Nanopillar Photovoltaics: Photon Management and Junction Engineering for Next-Generation Solar Cells

    Science.gov (United States)

    Mariani, Giacomo

    The sun delivers an amount of energy equivalent to ninety billion hydrogen bombs detonating each second. Despite the fact that only one billionth of that energy falls onto the surface of the Earth, one day of sunlight would be sufficient to power the whole human race energy needs for over half a century. Solar electricity represents an environmentally-benign source of power. However, such technology is still more than twice as expensive as natural gas-fired generators. III-V semiconductor nanopillars are defined as vertically aligned arrays of nanostructures that hold the promise to aggressively diminish the cost of the active photovoltaic cell by exploiting a fraction of material utilized in conventional planar schemes. In this dissertation, we assess the viability of two classes of high-performance nanopillar-based solar cells. We begin with the incorporation of dedicated conjugated polymers to achieve a hybrid organic/inorganic heterojunction. Such configuration introduces a high optical absorption arising from the polymeric layer in conjunction with an efficient carrier transport resulting from the semiconductor nanopillar array. We extend the controllability of the heterojunction properties by replacing traditional spin-casting methods with an electrodeposition technique where the polymer is formed and doped in-situ directly onto the nanopillar facets. The rational tuning of the electrical conductivity and energy level of the polymer translates into an enhanced photocurrent and open-circuit voltage, achieving 4.11% solar power conversion efficiency. We then turn our attention to all-semiconductor radial p-n homojunctions embedded in the nanopillars. The first architecture focuses on ex-situ ammonium-sulfide passivation and correlates the optoelectronic properties of the solar cell once two different types of transparent conducting oxides are adopted. The barrier formed at the contact/semiconductor interface greatly depends on the Hall polarity of the

  19. Junctional adhesion molecule-C (JAM-C) regulates polarized neutrophil transendothelial cell migration in vivo

    Science.gov (United States)

    Woodfin, Abigail; Voisin, Mathieu-Benoit; Beyrau, Martina; Colom, Bartomeu; Caille, Dorothée; Diapouli, Frantzeska-Maria; Nash, Gerard B; Chavakis, Triantafyllos; Albelda, Steven M.; Rainger, G Ed; Meda, Paolo; Imhof, Beat A.; Nourshargh, Sussan

    2011-01-01

    Neutrophil migration into inflamed tissues is a fundamental component of innate immunity. A decisive step in this process is the polarised migration of blood neutrophils through endothelial cells (ECs) lining the venular lumen (transendothelial cell migration; TEM) in a luminal to abluminal direction. Using real-time confocal imaging we report that neutrophils can exhibit disrupted polarised TEM (“hesitant” and “reverse”) in vivo. These events were noted in inflammation following ischemia-reperfusion injury, characterised by reduced expression of junctional adhesion molecule C (JAM-C) from EC junctions, and were enhanced by EC JAM-C blockade or genetic deletion. The results identify JAM-C as a key regulator of polarised neutrophil TEM in vivo and suggest that reverse TEM neutrophils can contribute to dissemination of systemic inflammation. PMID:21706006

  20. Enhanced efficiency in double junction polymer: Fullerene solar cells

    NARCIS (Netherlands)

    Moet, D.J.D.; Bruyn, P. de; Kotlarski, J.D.; Blom, P.W.M.

    2010-01-01

    Polymer solar cells based on the polyfluorene copolymer poly[9,9-didecanefluorene-alt-(bis-thienylene) benzothiadiazole] (PF10TBT) and the fullerene derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) exhibit a power conversion efficiency of 4%. However, the optimum thickness of the photoac

  1. An optimized efficient dual junction InGaN/CIGS solar cell: A numerical simulation

    Science.gov (United States)

    Farhadi, Bita; Naseri, Mosayeb

    2016-08-01

    The photovoltaic performance of an efficient double junction InGaN/CIGS solar cell including a CdS antireflector top cover layer is studied using Silvaco ATLAS software. In this study, to gain a desired structure, the different design parameters, including the CIGS various band gaps, the doping concentration and the thickness of CdS layer are optimized. The simulation indicates that under current matching condition, an optimum efficiency of 40.42% is achieved.

  2. Simulation of the Efficiency of CdS/CdTe Tandem Multi-Junction Solar Cells

    OpenAIRE

    Mirkamali, Ashrafalsadat S.; Muminov, Khikmat Kh.

    2016-01-01

    In this paper we study CdS/CdTe solar cells by means of AMPS-1D software. First we study the effect of thickness of semiconductor layers on the output parameters of the CdS/CdTe solar cell, such as density of short-circuit current, open circuit voltage, fill factor and efficiency. Numerical simulation shows that the highest efficiency of single-junction CdS/CdTe solar cell equal to 18.3% is achieved when the CdTe layer thickness is 1000 nm and a CdS layer is 60 nm. Then, in order to obtain th...

  3. Enhanced efficiency of graphene-silicon Schottky junction solar cells by doping with Au nanoparticles

    International Nuclear Information System (INIS)

    We have reported a method to enhance the performance of graphene-Si (Gr/Si) Schottky junction solar cells by introducing Au nanoparticles (NPs) onto the monolayer graphene and few-layer graphene. The electron transfer between Au NPs and graphene leads to the increased work function and enhanced electrical conductivity of graphene, resulting in a remarkable improvement of device efficiency. By optimizing the initial thickness of Au layers, the power conversion efficiency of Gr/Si solar cells can be increased by more than three times, with a maximum value of 7.34%. These results show a route for fabricating efficient and stable Gr/Si solar cells.

  4. HIV-associated disruption of tight and adherens junctions of oral epithelial cells facilitates HSV-1 infection and spread.

    Directory of Open Access Journals (Sweden)

    Irna Sufiawati

    Full Text Available Herpes simplex virus (HSV types 1 and 2 are the most common opportunistic infections in HIV/AIDS. In these immunocompromised individuals, HSV-1 reactivates and replicates in oral epithelium, leading to oral disorders such as ulcers, gingivitis, and necrotic lesions. Although the increased risk of HSV infection may be mediated in part by HIV-induced immune dysfunction, direct or indirect interactions of HIV and HSV at the molecular level may also play a role. In this report we show that prolonged interaction of the HIV proteins tat and gp120 and cell-free HIV virions with polarized oral epithelial cells leads to disruption of tight and adherens junctions of epithelial cells through the mitogen-activated protein kinase signaling pathway. HIV-induced disruption of oral epithelial junctions facilitates HSV-1 paracellular spread between the epithelial cells. Furthermore, HIV-associated disruption of adherens junctions exposes sequestered nectin-1, an adhesion protein and critical receptor for HSV envelope glycoprotein D (gD. Exposure of nectin-1 facilitates binding of HSV-1 gD, which substantially increases HSV-1 infection of epithelial cells with disrupted junctions over that of cells with intact junctions. Exposed nectin-1 from disrupted adherens junctions also increases the cell-to-cell spread of HSV-1 from infected to uninfected oral epithelial cells. Antibodies to nectin-1 and HSV-1 gD substantially reduce HSV-1 infection and cell-to-cell spread, indicating that HIV-promoted HSV infection and spread are mediated by the interaction of HSV gD with HIV-exposed nectin-1. Our data suggest that HIV-associated disruption of oral epithelial junctions may potentiate HSV-1 infection and its paracellular and cell-to-cell spread within the oral mucosal epithelium. This could be one of the possible mechanisms of rapid development of HSV-associated oral lesions in HIV-infected individuals.

  5. Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

    Directory of Open Access Journals (Sweden)

    W. Cui

    2010-04-01

    Full Text Available The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-α on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell® microporous filters and treated with TNF-α (10 or 100 ng/mL for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-α treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-α decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-α did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-α increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

  6. Simulation of the Mars Surface Solar Spectra for Optimized Performance of Triple-Junction Solar Cells

    Science.gov (United States)

    Edmondson, Kenneth M.; Joslin, David E.; Fetzer, Chris M.; King, RIchard R.; Karam, Nasser H.; Mardesich, Nick; Stella, Paul M.; Rapp, Donald; Mueller, Robert

    2007-01-01

    The unparalleled success of the Mars Exploration Rovers (MER) powered by GaInP/GaAs/Ge triple-junction solar cells has demonstrated a lifetime for the rovers that exceeded the baseline mission duration by more than a factor of five. This provides confidence in future longer-term solar powered missions on the surface of Mars. However, the solar cells used on the rovers are not optimized for the Mars surface solar spectrum, which is attenuated at shorter wavelengths due to scattering by the dusty atmosphere. The difference between the Mars surface spectrum and the AM0 spectrum increases with solar zenith angle and optical depth. The recent results of a program between JPL and Spectrolab to optimize GaInP/GaAs/Ge solar cells for Mars are presented. Initial characterization focuses on the solar spectrum at 60-degrees zenith angle at an optical depth of 0.5. The 60-degree spectrum is reduced to 1/6 of the AM0 intensity and is further reduced in the blue portion of the spectrum. JPL has modeled the Mars surface solar spectra, modified an X-25 solar simulator, and completed testing of Mars-optimized solar cells previously developed by Spectrolab with the modified X-25 solar simulator. Spectrolab has focused on the optimization of the higher efficiency Ultra Triple-Junction (UTJ) solar cell for Mars. The attenuated blue portion of the spectrum requires the modification of the top sub-cell in the GaInP/GaAs/Ge solar cell for improved current balancing in the triple-junction cell. Initial characterization confirms the predicted increase in power and current matched operation for the Mars surface 60-degree zenith angle solar spectrum.

  7. Characterization of nonconservative homologous junctions in mammalian cells.

    OpenAIRE

    Desautels, L; Brouillette, S; Wallenburg, J; Belmaaza, A; Gusew, N; Trudel, P; Chartrand, P

    1990-01-01

    Homologous recombination in mammalian cells between extrachromosomal molecules, as well as between episomes and chromosomes, can be mediated by a nonconservative mechanism. It has been proposed that the key steps in this process are the generation (by double-strand cleavage) of overlapping homologous ends, the creation of complementary single-strand ends (either by strand-specific exonuclease degradation or by unwinding of the DNA helix), and finally the creation of heteroduplex DNA by the an...

  8. Multiple junction II-VI compound photoelectrochemical cells

    Science.gov (United States)

    Russak, Michael A.

    1986-12-01

    The application of concepts used in producing tandem solid state photovoltaic devices to photoelectrochemical cells has resulted in improved spectral response and photovoltaic output. As in solid state devices, the key to achieving good photovoltaic performance is optimization of the semiconductor properties in each part of the tandem arrangement. This has been done for the thin film CdS/CdSe/sulfide-polysulfide system with an improvement of over 15 percent in conversion efficiency being obtained. Preliminary results showing significant current enhancement by the addition of a CdSe backwall electrode to the CdTe/selenide-polyselenide system are also reported.

  9. Electrophysiological effects of chilotoquine on tight junctions of immature rat Sertoli cells in vitro.

    Science.gov (United States)

    Okanlawon, A; Dym, M

    1999-01-01

    We investigated the effect of CQ, an antimalarial drug with antiprotease activity, and NH4Cl, a related amines on the development of intercellular tight junctions in cultured immature rat Sertoli cells. Sertoli cells were seeded in serum-free defined medium at a density of 3 x 10(6) cells/0.64 cm2/well on Matrigel-covered Millicell-HA filters. CQ (1 microM and 2 microM) or NH4Cl (6.25 mM and 12 mM) was added to the outer (basal) compartment of the bicameral system either on day 1 or day 7 of the culture. Formation of tight junctions was monitored by measurement of the transepithelial resistance (TER) at 24 hr intervals using an impedance meter. TER in untreated controls was 50 omega/cm2 on day 1, increased progressively to 80 omega/cm2 by day 7 and plateaued until day 12. The cells treated from day 1 with CQ showed dose-dependent progressive increase in TER until day 12, reaching 191 omega/cm2 in cells treated with 1 microM concentration. In cells treated with CQ starting from day 7 of culture onwards, TER patterns were similar to those noted following exposure to chloroquine from day 1. Also in cultures containing NH4Cl, in comparison to the control, the increase in TER was significantly higher. These observations demonstrate that CQ and HN4Cl promote tight junction formation between immature rat Sertoli cells invitro suggesting that antiproteases may be involved in the formation of blood-testis barrier. PMID:11205819

  10. Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells

    DEFF Research Database (Denmark)

    Del Vecchio, Giovanna; Tscheik, Christian; Tenz, Kareen;

    2012-01-01

    Claudin-5 is a tight junction (TJ) protein which limits the diffusion of small hydrophilic molecules. Thus, it represents a potential pharmacological target to improve drug delivery to the tissues protected by claudin-5-dependent barriers. Sodium caprate is known as an absorption enhancer which...... microscopy on live and fixed cells and isolated mouse brain capillaries, Western blotting and permeability assays were employed. Caprate reversibly reduced claudin-5 trans-interactions in TJ-free human embryonic kidney-293 cells expressing claudin-5-YFP. It decreased the membranous claudin-5 and the F...

  11. Design and Simulation of InGaN p-n Junction Solar Cell

    OpenAIRE

    Mesrane, A.; F. Rahmoune; A. Mahrane; A. Oulebsir

    2015-01-01

    The tunability of the InGaN band gap energy over a wide range provides a good spectral match to sunlight, making it a suitable material for photovoltaic solar cells. The main objective of this work is to design and simulate the optimal InGaN single-junction solar cell. For more accurate results and best configuration, the optical properties and the physical models such as the Fermi-Dirac statistics, Auger and Shockley-Read-Hall recombination, and the doping and temperature-dependent mobility ...

  12. Lipoxin A4 prevents tight junction disruption and delays the colonization of cystic fibrosis bronchial epithelial cells by Pseudomonas aeruginosa.

    Science.gov (United States)

    Higgins, Gerard; Fustero Torre, Coral; Tyrrell, Jean; McNally, Paul; Harvey, Brian J; Urbach, Valerie

    2016-06-01

    The specialized proresolution lipid mediator lipoxin A4 (LXA4) is abnormally produced in cystic fibrosis (CF) airways. LXA4 increases the CF airway surface liquid height and stimulates airway epithelial repair and tight junction formation. We report here a protective effect of LXA4 (1 nM) against tight junction disruption caused by Pseudomonas aeruginosa bacterial challenge together with a delaying action against bacterial invasion in CF airway epithelial cells from patients with CF and immortalized cell lines. Bacterial invasion and tight junction integrity were measured by gentamicin exclusion assays and confocal fluorescence microscopy in non-CF (NuLi-1) and CF (CuFi-1) bronchial epithelial cell lines and in primary CF cultures, grown under an air/liquid interface, exposed to either a clinical or laboratory strains of P. aeruginosa LXA4 delayed P. aeruginosa invasion and transepithelial migration in CF and normal bronchial epithelial cell cultures. These protective effects of LXA4 were inhibited by the ALX/FPR2 lipoxin receptor antagonist BOC-2. LXA4 prevented the reduction in mRNA biosynthesis and protein abundance of the tight junction protein ZO-1 and reduced tight junction disruption induced by P. aeruginsosa inoculation. In conclusion, LXA4 plays a protective role in bronchial epithelium by stimulating tight junction repair and by delaying and reducing the invasion of CF bronchial epithelial cells by P. aeruginsosa. PMID:27084849

  13. Effect of Toxoplasma gondii infection on the junctional complex of retinal pigment epithelial cells.

    Science.gov (United States)

    Nogueira, Alanderson R; Leve, Fernanda; Morgado-Diaz, José; Tedesco, Roberto Carlos; Pereira, Mirian Claudia S

    2016-04-01

    Ocular toxoplasmosis is the most frequent cause of uveitis, leading to partial or total loss of vision, with the retina the main affected structure. The cells of the retinal pigment epithelium (RPE) play an important role in the physiology of the retina and formation of the blood-retinal barrier. Several pathogens induce barrier dysfunction by altering tight junction (TJ) integrity. Here, we analysed the effect of infection by Toxoplasma gondii on TJ integrity in ARPE-19 cells. Loss of TJ integrity was demonstrated in T. gondii-infected ARPE-19 cells, causing increase in paracellular permeability and disturbance of the barrier function of the RPE. Confocal microscopy also revealed alteration in the TJ protein occludin induced by T. gondii infection. Disruption of junctional complex was also evidenced by scanning and transmission electron microscopy. Cell-cell contact loss was noticed in the early stages of infection by T. gondii with the visualization of small to moderate intercellular spaces. Large gaps were mostly observed with the progression of the infection. Thus, our data suggest that the alterations induced by T. gondii in the structural organization of the RPE may contribute to retinal injury evidenced by ocular toxoplasmosis. PMID:26928468

  14. Design and Simulation of InGaN p-n Junction Solar Cell

    Directory of Open Access Journals (Sweden)

    A. Mesrane

    2015-01-01

    Full Text Available The tunability of the InGaN band gap energy over a wide range provides a good spectral match to sunlight, making it a suitable material for photovoltaic solar cells. The main objective of this work is to design and simulate the optimal InGaN single-junction solar cell. For more accurate results and best configuration, the optical properties and the physical models such as the Fermi-Dirac statistics, Auger and Shockley-Read-Hall recombination, and the doping and temperature-dependent mobility model were taken into account in simulations. The single-junction In0.622Ga0.378N (Eg = 1.39 eV solar cell is the optimal structure found. It exhibits, under normalized conditions (AM1.5G, 0.1 W/cm2, and 300 K, the following electrical parameters: Jsc=32.6791 mA/cm2, Voc=0.94091 volts, FF = 86.2343%, and η=26.5056%. It was noticed that the minority carrier lifetime and the surface recombination velocity have an important effect on the solar cell performance. Furthermore, the investigation results show that the In0.622Ga0.378N solar cell efficiency was inversely proportional with the temperature.

  15. MIS and PN junction solar cells on thin-film polycrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ariotedjo, A.; Emery, K.; Cheek, G.; Pierce, P.; Surek, T.

    1981-05-01

    The Photovoltaic Advanced Silicon (PVAS) Branch at the Solar Energy Research Institute (SERI) has initiated a comparative study to assess the potential of MIS-type solar cells for low-cost terrestrial photovoltaic systems in terms of performance, stability, and cost-effectiveness. Several types of MIS and SIS solar cells are included in the matrix study currently underway. This approach compares the results of MIS and p/n junction solar cells on essentially identical thin-film polycrystalline silicon materials. All cell measurements and characterizations are performed using uniform testing procedures developed in the Photovoltaic Measurements and Evaluation (PV M and E) Laboratory at SERI. Some preliminary data on the different cell structures on thin-film epitaxial silicon on metallurgical-grade substrates are presented here.

  16. Correlated FLIM and PLIM for cell metabolism

    Science.gov (United States)

    Rück, A.; Breymayer, J.; Kalinina, S.

    2016-03-01

    Correlated imaging of phosphorescence and fluorescence lifetime parameters of metabolic markers is a challenge for direct investigating mechanisms related to cell metabolism and oxygen tension. A large variety of clinical phenotypes is associated with mitochondrial defects accomplished with changes in cell metabolism. In many cases the hypoxic microenvironment of cancer cells shifts metabolism from oxidative phosphorylation (OXPHOS) to anaerobic or aerobic glycolysis, a process known as "Warburg" effect. Also during stem cell differentiation a switch in cell metabolism is observed. A defective mitochondrial function associated with hypoxia has been invoked in many complex disorders such as type 2 diabetes, Alzheimers disease, cardiac ischemia/reperfusion injury, tissue inflammation and cancer. Cellular responses to oxygen tension have been studied extensively, optical imaging techniques based on time correlated single photon counting (TCSPC) to detect the underlying metabolic mechanisms are therefore of prominent interest. They offer the possibility by inspecting fluorescence decay characteristics of intrinsic coenzymes to directly image metabolic pathways. Moreover oxygen tension can be determined by considering the phosphorescence lifetime of a phosphorescent probe. The combination of both fluorescence lifetime imaging (FLIM) of coenzymes like NADH and FAD and phosphorescence lifetime (PLIM) of phosphorescent dyes could provide valuable information about correlation of metabolic pathways and oxygen tension.

  17. Guidelines for the Bandgap Combinations and Absorption Windows for Organic Tandem and Triple-Junction Solar Cells

    Directory of Open Access Journals (Sweden)

    Ben Minnaert

    2012-10-01

    Full Text Available Organic solar cells have narrow absorption windows, compared to the absorption band of inorganic semiconductors. A possible way to capture a wider band of the solar spectrum—and thus increasing the power conversion efficiency—is using more solar cells with different bandgaps in a row, i.e., a multi-junction solar cell. We calculate the ideal material characteristics (bandgap combinations and absorption windows for an organic tandem and triple-junction solar cell, as well as their acceptable range. In this way, we give guidelines to organic material designers.

  18. The extracellular regulated kinases (ERK) 1/2 mediate cannabinoid-induced inhibition of gap junctional communication in endothelial cells

    OpenAIRE

    Brandes, R P; Popp, R; G. Ott; Bredenkötter, D; Wallner, C.; Busse, R.; Fleming, I.

    2002-01-01

    Cannabinoids are potent inhibitors of endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxations. We set out to study the mechanism underlying this effect and the possible role of cannabinoid-induced changes in intercellular gap junction communication.In cultured endothelial cells, Δ9-tetrahydrocannabinol (Δ9-THC) and the cannabinoid receptor agonist HU210, increased the phosphorylation of extracellular regulated kinases 1/2 (ERK1/2) and inhibited gap junctional communication, as ...

  19. Specific permeability and selective formation of gap junction channels in connexin-transfected HeLa cells

    OpenAIRE

    1995-01-01

    DNAs coding for seven murine connexins (Cx) (Cx26, Cx31, Cx32, Cx37, Cx40, Cx43, and Cx45) are functionally expressed in human HeLa cells that were deficient in gap junctional communication. We compare the permeabilities of gap junctions comprised of different connexins to iontophoretically injected tracer molecules. Our results show that Lucifer yellow can pass through all connexin channels analyzed. On the other hand, propidium iodide and ethidium bromide penetrate very poorly or not at all...

  20. Vitamin D3 regulates the formation and degradation of gap junctions in androgen-responsive human prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Linda Kelsey

    Full Text Available 1α-25(OH2 vitamin D3 (1-25D, an active hormonal form of Vitamin D3, is a well-known chemopreventive and pro-differentiating agent. It has been shown to inhibit the growth of several prostate cancer cell lines. Gap junctions, formed of proteins called connexins (Cx, are ensembles of cell-cell channels, which permit the exchange of small growth regulatory molecules between adjoining cells. Cell-cell communication mediated by gap junctional channels is an important homeostatic control mechanism for regulating cell growth and differentiation. We have investigated the effect of 1-25D on the formation and degradation of gap junctions in an androgen-responsive prostate cancer cell line, LNCaP, which expresses retrovirally-introduced Cx32. Connexin32 is expressed by the luminal and well-differentiated cells of normal prostate and prostate tumors. Our results document that 1-25D enhances the expression of Cx32 and its subsequent assembly into gap junctions. Our results further show that 1-25D prevents androgen-regulated degradation of Cx32, post-translationally, independent of androgen receptor (AR-mediated signaling. Finally, our findings document that formation of gap junctions sensitizes Cx32-expressing LNCaP cells to the growth inhibitory effects of 1-25D and alters their morphology. These findings suggest that the growth-inhibitory effects of 1-25D in LNCaP cells may be related to its ability to modulate the assembly of Cx32 into gap junctions.

  1. "Direct" measurement of sheet resistance in inter-subcell layers of multi-junction solar cells

    Science.gov (United States)

    Rumyantsev, Valery D.; Larionov, Valery R.; Pokrovskiy, Pavel V.

    2015-09-01

    The multi-junction cells are sensitive to chromatic aberrations inherent to the lens-type concentrators. At spectrally and spatially inhomogeneous distribution of incident light, considerable lateral currents flow along the inter-subcell layers causing a voltage drop across corresponding sheet resistance and, consequently, a decrease in the cell conversion efficiency. The sheet resistance unit is Ohm-per-square that corresponds to the resistance between two bar-type electrodes on the opposite sides of a thin conductive square. A method of "direct" measurement of this parameter is proposed using lasers for local illumination of the strip-in-shape parts of a rectangular-in-form tested cell. These illuminated parts play a role of electrodes for a lateral current induced by photoexitation. Wavelengths of the lasers have to be chosen to generate photocurrents independently in the neighboring subcells, as well as locally in the upper and lower ones. SPICE model of the method is analyzed and experimental results on the InGaP/InGaAs/Ge triple-junction solar cells are presented.

  2. Analyses and Simulation of V-I Characteristics for Solar Cells Based on P-N Junction

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jian-bang; REN Ju; GUO Wen-ge; HOU Chao-qi

    2005-01-01

    Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab software, the V-I characteristics of diodes and solar cells were simulated, and a computer simulation model of the solar cells based on P-N junction was also established. Based on the simulation model, the influences of solar cell's internal resistances on open-circuit voltage and short-circuit current under certain illumination were numerically analyzed and solved. The simulation results showed that the equivalent series resistance and shunt resistance could strongly affect the V-I characteristics of solar cell, but their influence styles were different.

  3. ZnSe/GaAs/Ge Triple Junction Solar Cell and Its Structure Design

    Institute of Scientific and Technical Information of China (English)

    Aikun WANG; Guochang LI; Guoxiang ZHOU; Jertrude F. Neumark

    2004-01-01

    A new method is given to increase doping concentration of p-type ZnSe up to 1× 10i8 cm-3 through adding a little Te. This method gets over the difficulty of the high doping concentration of p-type ZnSe for many years. The external quantum efficiency (QE) of ZnSe p-n junction solar cell has been measured, and ZnSe is a good material of the top cell in the tandem solar cells. The solar cells made from ZnSe/GaAs/Ge can cover 94% of the total solar spectrum under AM (air mass) 1.5, and their theoretical efficiency is 56%.

  4. Altered Expression of Connexin-43 and Impaired Capacity of Gap Junctional Intercellular Communication in Prostate Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    XING Yifei; XIAO Yajun; ZENG FuQing; ZHAO Jun; XIAO Chuanguo; XIONG Ping; FENG Wei

    2007-01-01

    Connexin-43 (Cx43) expression in prostate cancer (PCa) cells and the potency of gap junctional intercellular communication (GJIC) in the cells were investigated, with an attempt to elucidate the reason why the so-called "bystander effect" mediated by thymidine kinase (TK) suicide gene therapy on PCa cells is not of significance and to explore the role of GJIC in PCa carcinogenesis.mRNA and protein expression of Cx43 in a PCa cell line PC-3m was detected by reverse-transcription polymerase chain reaction (RT-PCR) and strapt-avidin-biotin-enzyme complex (SABC) immunohistochemical staining, and inherent GJIC of PC-3m cells was assayed by scrape-loading and dye transfer (SLDT) assay. The expression of Cx43 in human normal and malignant prostate tissues was determined by SABC immunohistochemistry as well. It was found that Cx43 mRNA and protein expression in PC-3m cells was slightly reduced as compared with positive controls and the location of Cx43 protein was aberrant in cytoplasm rather than on membrane. Assessment of paraffin sections demonstrated that the expression of Cx43 protein in PCa cells was abnormally located and markedly diminished as compared with normal prostatic epithelial ones, displaying a negative correlation to the pathological grade (χ2=4.025, P<0.05). Additionally, capacity of inherent GJIC in PC-3m cells was disrupted, which was semi-quantified as (+) or (-). It was indicated that both down-regulated expression of Cx43 mRNA and aberrant location of Cx43 protein participated in the mechanisms leading to deficient GJIC in PC-3m cells. Lack of efficient GJIC is a molecular event, which may contribute not only to limited extent of "bystander effect", but also to initiation and progression of prostatic neoplasm.

  5. Striatins as plaque molecules of zonulae adhaerentes in simple epithelia, of tessellate junctions in stratified epithelia, of cardiac composite junctions and of various size classes of lateral adherens junctions in cultures of epithelia- and carcinoma-derived cells.

    Science.gov (United States)

    Franke, Werner W; Rickelt, Steffen; Zimbelmann, Ralf; Dörflinger, Yvette; Kuhn, Caecilia; Frey, Norbert; Heid, Hans; Rosin-Arbesfeld, Rina

    2015-03-01

    Proteins of the striatin family (striatins 1-4; sizes ranging from 90 to 110 kDa on SDS-polyacrylamide gel electrophoresis) are highly homologous in their amino acid sequences but can differ in their cell-type-specific gene expression patterns and biological functions. In various cell types, we have found one, two or three polypeptides of this evolutionarily old and nearly ubiquitous family of proteins known to serve as scaffold proteins for diverse protein complexes. Light and electron microscopic immunolocalization methods have revealed striatins in mammalian cell-cell adherens junctions (AJs). In simple epithelia, we have localized striatins as constitutive components of the plaques of the subapical zonulae adhaerentes of cells, including intestinal, glandular, ductal and urothelial cells and hepatocytes. Striatins colocalize with E-cadherin or E-N-cadherin heterodimers and with the plaque proteins α- and β-catenin, p120 and p0071. In some epithelia and carcinomas and in cultured cells derived therefrom, striatins are also seen in lateral AJs. In stratified epithelia and in corresponding squamous cell carcinomas, striatins can be found in plaques of some forms of tessellate junctions. Moreover, striatins are major plaque proteins of composite junctions (CJs; areae compositae) in the intercalated disks connecting cardiomyocytes, colocalizing with other CJ molecules, including plectin and ankyrin-G. We discuss the "multimodulator" scaffold roles of striatins in the initiation and regulation of the formation of various complex particles and structures. We propose that striatins are included in the diagnostic candidate list of proteins that, in the CJs of human hearts, can occur in mutated forms in the pathogeneses of hereditary cardiomyopathies, as seen in some types of genetically determined heart damage in boxer dogs. PMID:25501894

  6. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells

    OpenAIRE

    Sara Jäckle; Matthias Mattiza; Martin Liebhaber; Gerald Brönstrup; Mathias Rommel; Klaus Lips; Silke Christiansen

    2015-01-01

    We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and ...

  7. Cell integrated multi-junction thermocouple array for solid oxide fuel cell temperature sensing: N+1 architecture

    Science.gov (United States)

    Ranaweera, Manoj; Kim, Jung-Sik

    2016-05-01

    Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si - 95:2:2:1 by wt.) and chromel (Ni:Cr - 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

  8. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    Science.gov (United States)

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-01

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects. PMID:26971560

  9. Epithelial tricellular junctions act as interphase cell shape sensors to orient mitosis.

    Science.gov (United States)

    Bosveld, Floris; Markova, Olga; Guirao, Boris; Martin, Charlotte; Wang, Zhimin; Pierre, Anaëlle; Balakireva, Maria; Gaugue, Isabelle; Ainslie, Anna; Christophorou, Nicolas; Lubensky, David K; Minc, Nicolas; Bellaïche, Yohanns

    2016-02-25

    The orientation of cell division along the long axis of the interphase cell--the century-old Hertwig's rule--has profound roles in tissue proliferation, morphogenesis, architecture and mechanics. In epithelial tissues, the shape of the interphase cell is influenced by cell adhesion, mechanical stress, neighbour topology, and planar polarity pathways. At mitosis, epithelial cells usually adopt a rounded shape to ensure faithful chromosome segregation and to promote morphogenesis. The mechanisms underlying interphase cell shape sensing in tissues are therefore unknown. Here we show that in Drosophila epithelia, tricellular junctions (TCJs) localize force generators, pulling on astral microtubules and orienting cell division via the Dynein-associated protein Mud independently of the classical Pins/Gαi pathway. Moreover, as cells round up during mitosis, TCJs serve as spatial landmarks, encoding information about interphase cell shape anisotropy to orient division in the rounded mitotic cell. Finally, experimental and simulation data show that shape and mechanical strain sensing by the TCJs emerge from a general geometric property of TCJ distributions in epithelial tissues. Thus, in addition to their function as epithelial barrier structures, TCJs serve as polarity cues promoting geometry and mechanical sensing in epithelial tissues. PMID:26886796

  10. Influence of drugs on gap junctions in glioma cell lines and primary astrocytes in vitro

    Directory of Open Access Journals (Sweden)

    Zahra eMoinfar

    2014-05-01

    Full Text Available Gap junctions (GJs are hemichannels on cell membrane. Once they are intercellulary connected to the neighboring cells, they build a functional syncytium which allows rapid transfer of ions and molecules between cells. This characteristic makes GJs a potential modulator in proliferation, migration and development of the cells. So far, several types of GJs are recognized on different brain cells as well as in glioma. Astrocytes, as one of the major cells that maintain neuronal homeostasis, express different types of GJs that let them communicate with neurons, oligodendrocytes and endothelial cells of the blood brain barrier; however, the main GJ in astrocytes is connexin 43. There are different cerebral diseases in which astrocyte GJs might play a role. Several drugs have been reported to modulate gap junctional communication in the brain which can consequently have beneficial or detrimental effects on the course of treatment in certain diseases. However, the exact cellular mechanism behind those pharmaceutical efficacies on GJs is not well-understood. Accordingly, how specific drugs would affect GJs and what some consequent specific brain diseases would be are the interests of the authors of this chapter. We would focus on pharmaceutical effects on GJs on astrocytes in specific diseases where GJs could possibly play a role including: 1 migraine and a novel therapy for migraine with aura, 2 neuroautoimmune diseases and immunomodulatory drugs in the treatment of demyelinating diseases of the central nervous system such as multiple sclerosis, 3 glioma and antineoplastic and anti-inflammatory agents that are used in treating brain tumors and 4 epilepsy and anticonvulsants that are widely used for seizures therapy. All of the above-mentioned therapeutic categories can possibly affect GJs expression of astrocytes and the role is discussed in the upcoming chapter.

  11. Molecular flexibility can influence the stimulatory ability of receptor–ligand interactions at cell–cell junctions

    OpenAIRE

    Qi, Shuyan; Krogsgaard, Michelle; Davis, Mark M; Chakraborty, Arup K.

    2006-01-01

    Direct cell–cell communication is crucial for many processes in biology, particularly embryogenesis, interactions between hematopoetic cells, and in the nervous system. This communication is often mediated by the binding of receptors to cognate ligands at a cell–cell junction. One such interaction that is very important for the development of many immune responses is the binding of the αβ T cell receptor for antigen (TCR) on T lymphocytes with peptide–MHC complexes on other cells. In general,...

  12. Mast Cell Tryptase Reduces Junctional Adhesion Molecule-A (JAM-A) Expression in Intestinal Epithelial Cells: Implications for the Mechanisms of Barrier Dysfunction in Irritable Bowel Syndrome.

    LENUS (Irish Health Repository)

    Wilcz-Villega, Ewa M

    2013-07-01

    The objective of this study was to investigate how mast cell tryptase may influence intestinal permeability and tight junction (TJ) proteins in vitro and explore translation to irritable bowel syndrome (IBS).

  13. Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation

    Directory of Open Access Journals (Sweden)

    Wang Ting

    2012-08-01

    Full Text Available Abstract Background Exposure to particulate matter (PM is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. Objectives We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC barrier integrity and enhanced cardiopulmonary dysfunction. Methods Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 μm. Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. Results PM exposure induced tight junction protein Zona occludens-1 (ZO-1 relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and β-catenin. N-acetyl-cysteine (NAC, 5 mM reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2, in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. Conclusions These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.

  14. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    Science.gov (United States)

    Jorgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne; Civitelli, Roberto; Sorensen, Ole Helmer; Steinberg, Thomas H.

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium.

  15. Behavior of Primary Cilia and Tricellular Tight Junction Proteins during Differentiation in Temperature-Sensitive Mouse Cochlear Precursor Hair Cells.

    Science.gov (United States)

    Kakuki, Takuya; Kaneko, Yakuto; Takano, Kenichi; Ninomiya, Takafumi; Kohno, Takayuki; Kojima, Takashi; Himi, Tetsuo

    2016-01-01

    In the sensory hair cells of the mammalian cochlea, the primary cilia in the planar cell polarity as well as the tight junctions in the epithelial cell polarity and the barrier are important to maintain normal hearing. Temperature-sensitive mouse cochlear precursor hair cells were used to investigate the behavior of primary cilia and tricellular tight junction proteins during the differentiation of sensory hair cells. In undifferentiated cells (incubated at 33°C), many acetylated tubulin-positive primary cilia were observed, and each was accompanied with an x03B3;-tubulin-positive basal body. The primary cilia had a '9 + 0' architecture with nine outer microtubule doublets but lacking a central pair of microtubules. In differentiated cells (incubated at 39°C), acetylated tubulin-positive primary cilia as well as acetylated tubulin-positive cilia-like structures were partially observed on the cell surface. In differentiated cells, the number of primary cilia was markedly reduced compared with undifferentiated cells, and innumerable cilia-like structures with no ciliary pockets were partially observed on the cell surface. In undifferentiated cells, few tricellulin molecules and lipolysis-stimulated lipoprotein receptors (LSRs) were observed in the cytoplasm. In differentiated cells, many tricellulin molecules and LSRs were observed on the membranes and within the cytoplasm. Conditional immortalized mouse cochlear precursor hair cells may be useful to investigate the roles of primary cilia and tricellular tight junctions during cellular differentiation and degeneration such as apoptosis. PMID:27115742

  16. Physical aspects of a-Si:H/c-Si hetero-junction solar cells

    International Nuclear Information System (INIS)

    We report on the basic properties of amorphous/crystalline hetero-junctions (a-Si:H/c-Si), their effects on the recombination of excess carriers and its influence on the a-Si:H/c-Si hetero-junction solar cells. For that purpose we measured the gap state density distribution of thin a-Si:H layers and determined its dependence on deposition temperature and doping by an improved version of near-UV-photoelectron spectroscopy. Furthermore, the Fermi level position in the a-Si:H and the valence band offset were directly measured. In combination with interface sensitive methods such as surface photovoltage analysis and our numerical simulation program AFORS-HET, we found an optimum in wafer pretreatment, doping and deposition temperature for efficient a-Si:H/c-Si solar cells without an i-type a-Si:H buffer layer. We reached at maximum 19.8% certified efficiency by a deposition at 210 deg. C with an emitter doping of 2000 ppm of B2H6 on a well cleaned pyramidally structured c-Si(n) wafer

  17. Application of LBIC measurements for characterisation of triple junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kwarikunda, N., E-mail: Nicholas.kwarikunda@live.nmmu.ac.za [Nelson Mandela Metropolitan University, P.O. BOX 77000, Port Elizabeth, 6031 (South Africa); Makerere University, P.O. BOX 7062, Kampala (Uganda); Dyk, E.E. van; Vorster, F.J. [Nelson Mandela Metropolitan University, P.O. BOX 77000, Port Elizabeth, 6031 (South Africa); Okullo, W. [Makerere University, P.O. BOX 7062, Kampala (Uganda); Munji, M.K. [Kenyatta University, P.O. BOX 43844-00100, Nairobi (Kenya)

    2014-04-15

    In this study the Light Beam Induced Current (LBIC) imaging technique was used to characterise InGaP/InGaAs/Ge triple junction solar cells. The study focused on the use of monochromatic and solar light as beam probes to obtain photocurrent response maps from which the presence of any current reducing features on the solar cell were identified. Point illuminated current voltage (I–V) curves were obtained simultaneously while LBIC scanning measurements were being made. Curve fitting using an interval division algorithm based on the single diode model was performed to extract basic point device and performance parameters to give a rough indication of the functioning of the triple junction device. Using red and blue lasers as beam probes, reverse voltage breakdown was observed on the I–V curves which could be attributed to the Ge bottom subcell not being fully activated. The extracted parameters obtained when using monochromatic and solar light beam probes showed a large variation, indicating the dependence of I–V parameters on the spectral content of the beam probe.

  18. Application of LBIC measurements for characterisation of triple junction solar cells

    International Nuclear Information System (INIS)

    In this study the Light Beam Induced Current (LBIC) imaging technique was used to characterise InGaP/InGaAs/Ge triple junction solar cells. The study focused on the use of monochromatic and solar light as beam probes to obtain photocurrent response maps from which the presence of any current reducing features on the solar cell were identified. Point illuminated current voltage (I–V) curves were obtained simultaneously while LBIC scanning measurements were being made. Curve fitting using an interval division algorithm based on the single diode model was performed to extract basic point device and performance parameters to give a rough indication of the functioning of the triple junction device. Using red and blue lasers as beam probes, reverse voltage breakdown was observed on the I–V curves which could be attributed to the Ge bottom subcell not being fully activated. The extracted parameters obtained when using monochromatic and solar light beam probes showed a large variation, indicating the dependence of I–V parameters on the spectral content of the beam probe.

  19. Thermal influence on charge carrier transport in solar cells based on GaAs PN junctions

    Energy Technology Data Exchange (ETDEWEB)

    Osses-Márquez, Juan; Calderón-Muñoz, Williams R., E-mail: wicalder@ing.uchile.cl [Department of Mechanical Engineering, University of Chile, Beauchef 850, Santiago (Chile)

    2014-10-21

    The electron and hole one-dimensional transport in a solar cell based on a Gallium Arsenide (GaAs) PN junction and its dependency with electron and lattice temperatures are studied here. Electrons and heat transport are treated on an equal footing, and a cell operating at high temperatures using concentrators is considered. The equations of a two-temperature hydrodynamic model are written in terms of asymptotic expansions for the dependent variables with the electron Reynolds number as a perturbation parameter. The dependency of the electron and hole densities through the junction with the temperature is analyzed solving the steady-state model at low Reynolds numbers. Lattice temperature distribution throughout the device is obtained considering the change of kinetic energy of electrons due to interactions with the lattice and heat absorbed from sunlight. In terms of performance, higher values of power output are obtained with low lattice temperature and hot energy carriers. This modeling contributes to improve the design of heat exchange devices and thermal management strategies in photovoltaic technologies.

  20. Thermal influence on charge carrier transport in solar cells based on GaAs PN junctions

    International Nuclear Information System (INIS)

    The electron and hole one-dimensional transport in a solar cell based on a Gallium Arsenide (GaAs) PN junction and its dependency with electron and lattice temperatures are studied here. Electrons and heat transport are treated on an equal footing, and a cell operating at high temperatures using concentrators is considered. The equations of a two-temperature hydrodynamic model are written in terms of asymptotic expansions for the dependent variables with the electron Reynolds number as a perturbation parameter. The dependency of the electron and hole densities through the junction with the temperature is analyzed solving the steady-state model at low Reynolds numbers. Lattice temperature distribution throughout the device is obtained considering the change of kinetic energy of electrons due to interactions with the lattice and heat absorbed from sunlight. In terms of performance, higher values of power output are obtained with low lattice temperature and hot energy carriers. This modeling contributes to improve the design of heat exchange devices and thermal management strategies in photovoltaic technologies.

  1. Role of connexin (gap junction) genes in cell growth control and carcinogenesis

    International Nuclear Information System (INIS)

    Gap junctional intercellular communication (GJIC) is considered to play a key role in the maintenance of tissue independence and homeostasis in multicellular organisms by controlling the growth of GJIC-connected cells. Gap junction channels are composed of connexin molecules and, so far, more than a dozen different connexin genes have been shown to be expressed in mammals. Reflecting the importance of GJIC in various physiological functions, deletion of different connexin genes from mice results in various disorders, including cancers, heart malformation or conduction abnormality, cataract, etc. The possible involvement of aberrant GJIC in abnormal cell growth and carcinogenesis has long been postulated and recent studies in our own and other laboratories have confirmed that expression and function of connexin genes play an important role in cell growth control. Thus, almost all malignant cells show altered homologous and/or heterologous GJIC and are often associated with aberrant expression or localization of connexins. Aberrant localization of connexins in some tumour cells is associated with lack of function of cell adhesion molecules, suggesting the importance of cell-cell recognition for GJIC. Transfection of connexin genes into tumorigenic cells restores normal cell growth, supporting the idea that connexins form a family of tumour-suppressor genes. Some studies also show that specific connexins may be necessary to control growth of specific cell types. We have produced various dominant-negative mutants of Cx26, Cx32 and Cx43 and showed that some of them prevent the growth control exerted by the corresponding wild-type genes. However, we have found that connexins 32, 37 and 43 genes are rarely mutated in tumours. In some of these studies, we noted that connexin expression per se, rather than GJIC level, is more closely related to growth control, suggesting that connexins may have a GJIC-independent function. We have recently created a transgenic mouse strain

  2. Application of Nanostructured Materials and Multi-junction Structure in Polymer Solar Cells

    KAUST Repository

    Gao, Yangqin

    2015-12-09

    With power conversion efficiency surpassing the 10% milestone for commercialization, photovoltaic technology based on solution-processable polymer solar cells (PSCs) provides a promising route towards a cost-efficient strategy to address the ever-increasing worldwide energy demands. However, to make PSCs successful, challenges such as insufficient light absorption, high maintenance costs, and relatively high production costs must be addressed. As solutions to some of these problems, the unique properties of nanostructured materials and complimentary light absorption in multi-junction device structure could prove to be highly beneficial. As a starting point, integrating nanostructure-based transparent self-cleaning surfaces in PSCs was investigated first. By controlling the length of the hydrothermally grown ZnO nanorods and covering their surface with a thin layer of chemical vapor-deposited SiO2, a highly transparent and UV-resistant superhydrophobic surface was constructed. Integrating the transparent superhydrophobic surface in a PSC shows minimal impact on the figure of merit of the PSC. To address the low mechanical durability of the transparent superhydrophobic surface based on SiO2-coated ZnO nanorods, a novel method inspired by the water condensation process was developed. This method involved directly growing hollow silica half-nanospheres on the substrate through the condensation of water in the presence of a silica precursor. Benefit from the decreased back scattering efficiency and increased light transport mean free path arise from the hollow nature, a transparent superhydrophobic surface was realized using submicrometer sized silica half-nanospheres. The decent mechanical property of silica and the “direct-grown” protocol are expected to impart improved mechanical durability to the transparent superhydrophobic surface. Regarding the application of multi-junction device structure in PSCs, homo multi-junction PSCs were constructed from an identical

  3. Simulation of Temperature Characteristics of InGaP/InGaAs/Ge Triple-Junction Solar Cell under Concentrated Light

    Science.gov (United States)

    Sakurada, Yuya; Ota, Yasuyuki; Nishioka, Kensuke

    2011-04-01

    Using an equivalent circuit model, the temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under concentrated light conditions were analyzed in detail. The current-voltage (I-V) characteristics of the single-junction solar cells (InGaP, InGaAs, and Ge solar cells) were measured at various temperatures. From the dark I-V characteristics of each single-junction solar cell, the diode parameters and temperature exponents were extracted. The extracted diode parameters and temperature exponents were applied to the equivalent circuit model for the triple-junction solar cell, and the solar-cell performance was calculated. There was good agreement between the measured and calculated I-V characteristics of the triple-junction solar cell at various temperatures under concentrated light conditions.

  4. Simulation of the Efficiency of CdS/CIGS Tandem Multi-Junction Solar Cells Using AMPS-1D

    CERN Document Server

    Mirkamali, Ashrafalsadat S

    2016-01-01

    In this paper we conduct numerical simulation of CdS/CIGS solar cells by use of the AMPS-1D software aiming to formulate the optimal design of the new multi-junction tandem solar cell providing its most efficient operation. We start with the numerical simulation of single-junction CdS/CIGS solar cells, which shows that its highest efficiency of 17.3% could be achieved by the thickness of CIGS p-layer of 200 nm. This result is in a good agreement with experimental data where the highest efficiency was 17.1% with the solar cell thickness of 1 micron. By use of the results of the numerical simulation of the single-junction solar cells we developed the design and conducted optimization of the new multi-junction tandem CdS/CIGS solar cell structure. Numerical simulation shows that the maximum efficiency of this solar cell is equal to 48.3%, which could be obtained with the thickness of the CIGS p-layer of 600 nm at a standard illumination of AM 1.5.

  5. Effects of Nonuniform Incident Illumination on the Thermal Performance of a Concentrating Triple Junction Solar Cell

    Directory of Open Access Journals (Sweden)

    Fahad Al-Amri

    2014-01-01

    Full Text Available A numerical heat transfer model was developed to investigate the temperature of a triple junction solar cell and the thermal characteristics of the airflow in a channel behind the solar cell assembly using nonuniform incident illumination. The effects of nonuniformity parameters, emissivity of the two channel walls, and Reynolds number were studied. The maximum solar cell temperature sharply increased in the presence of nonuniform light profiles, causing a drastic reduction in overall efficiency. This resulted in two possible solutions for solar cells to operate in optimum efficiency level: (i adding new receiver plate with higher surface area or (ii using forced cooling techniques to reduce the solar cell temperature. Thus, surface radiation exchanges inside the duct and Re significantly reduced the maximum solar cell temperature, but a conventional plain channel cooling system was inefficient for cooling the solar cell at medium concentrations when the system was subjected to a nonuniform light distribution. Nonuniformity of the incident light and surface radiation in the duct had negligible effects on the collected thermal energy.

  6. Characterizing the effects of silver alloying in chalcopyrite CIGS solar cells with junction capacitance methods

    Energy Technology Data Exchange (ETDEWEB)

    Erslev, Peter T.; Hanket, Gregory M.; Shafarman, William N.; Cohen, J. David

    2009-04-01

    A variety of junction capacitance-based characterization methods were used to investigate alloys of Ag into Cu(In1-xGax)Se2 photovoltaic solar cells over a broad range of compositions. These alloys show encouraging trends of increasing VOC with increasing Ag content, opening the possibility of wide-gap cells for use in tandem device applications. Drive level capacitance profiling (DLCP) has shown very low free carrier concentrations for all Ag-alloyed devices, in some cases less than 1014 cm-3, which is roughly an order of magnitude lower than that of CIGS devices. Transient photocapacitance spectroscopy has revealed very steep Urbach edges, with energies between 10 meV and 20 meV, in the Ag-alloyed samples. This is in general lower than the Urbach edges measured for standard CIGS samples and suggests a significantly lower degree of structural disorder.

  7. The tight junction does not allow lipid molecules to diffuse from one epithelial cell to the next

    OpenAIRE

    van Meer, G.; Gumbiner, B.; Simons, K.

    1986-01-01

    The tight junction (zonula occludens) links epithelial cells into a monolayer by forming a continuous belt of sealing contacts around the apex of each cell. They appear in thin sections as if they were 'fusions' between the apposed plasma membranes and in freeze-fracture replicas as patterns of complementary strands and furrows. These images have led to the proposal that the core of the tight junction is formed by a hexagonal cylinder of lipids. In this model, the cytoplasmic leaflet of the a...

  8. Rescue of perfluorooctanesulfonate (PFOS)-mediated Sertoli cell injury by overexpression of gap junction protein connexin 43

    Science.gov (United States)

    Li, Nan; Mruk, Dolores D.; Chen, Haiqi; Wong, Chris K. C.; Lee, Will M.; Cheng, C. Yan

    2016-07-01

    Perfluorooctanesulfonate (PFOS) is an environmental toxicant used in developing countries, including China, as a stain repellent for clothing, carpets and draperies, but it has been banned in the U.S. and Canada since the late 2000s. PFOS perturbed the Sertoli cell tight junction (TJ)-permeability barrier, causing disruption of actin microfilaments in cell cytosol, perturbing the localization of cell junction proteins (e.g., occluden-ZO-1, N-cadherin-ß-catenin). These changes destabilized Sertoli cell blood-testis barrier (BTB) integrity. These findings suggest that human exposure to PFOS might induce BTB dysfunction and infertility. Interestingly, PFOS-induced Sertoli cell injury associated with a down-regulation of the gap junction (GJ) protein connexin43 (Cx43). We next investigated if overexpression of Cx43 in Sertoli cells could rescue the PFOS-induced cell injury. Indeed, overexpression of Cx43 in Sertoli cells with an established TJ-barrier blocked the disruption in PFOS-induced GJ-intercellular communication, resulting in the re-organization of actin microfilaments, which rendered them similar to those in control cells. Furthermore, cell adhesion proteins that utilized F-actin for attachment became properly distributed at the cell-cell interface, resealing the disrupted TJ-barrier. In summary, Cx43 is a good target that might be used to manage PFOS-induced reproductive dysfunction.

  9. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures

    Science.gov (United States)

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-07-01

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the

  10. Analysis of radiation resistance of InGaP/GaAs dual-junction thin-film space solar cell

    International Nuclear Information System (INIS)

    Thin-film III-V multi-junction solar cells can realize the advantages of being high-efficiency and light-weight, as such these cells meets the requirement for higher specific power and lower stowage volume solar panels. Here we report the development results of an InGaP/GaAs thin-film dual-junction (TF2J) solar cell. In this paper, we study the radiation resistance of the TF2J cells with efficiency of 20-23% under AM0.1 sun at 25degC. The cells were subjected to proton irradiation with an energy range of 100keV-10MeV. The results were compared with the radiation resistance of a conventional InGaP/GaAs/Ge triple-junction (3J) cell. In the proton energy range of 200-400keV, radiation resistance of the TF2J cell is superior to that of the 3J cell. Particularly, the 1sc of the TF2J cell is significantly higher than that of the 3J cell after exposure to 380keV protons, which results in higher remaining factor of Pmax for the TF2J cell. In additions, Voc of the cells after the irradiations are almost equivalent, even though the TF2J cell is a dual-junction structure. The higher 1sc of the TF2J cell after irradiation is due to higher radiation resistance of the GaAs subcell according to the comparison of the spectral response. (author)

  11. Regulation of Hemichannels and Gap Junction Channels by Cytokines in Antigen-Presenting Cells

    Directory of Open Access Journals (Sweden)

    Pablo J. Sáez

    2014-01-01

    Full Text Available Autocrine and paracrine signals coordinate responses of several cell types of the immune system that provide efficient protection against different challenges. Antigen-presenting cells (APCs coordinate activation of this system via homocellular and heterocellular interactions. Cytokines constitute chemical intercellular signals among immune cells and might promote pro- or anti-inflammatory effects. During the last two decades, two membrane pathways for intercellular communication have been demonstrated in cells of the immune system. They are called hemichannels (HCs and gap junction channels (GJCs and provide new insights into the mechanisms of the orchestrated response of immune cells. GJCs and HCs are permeable to ions and small molecules, including signaling molecules. The direct intercellular transfer between contacting cells can be mediated by GJCs, whereas the release to or uptake from the extracellular milieu can be mediated by HCs. GJCs and HCs can be constituted by two protein families: connexins (Cxs or pannexins (Panxs, which are present in almost all APCs, being Cx43 and Panx1 the most ubiquitous members of each protein family. In this review, we focus on the effects of different cytokines on the intercellular communication mediated by HCs and GJCs in APCs and their impact on purinergic signaling.

  12. InP tunnel junction for InGaAs/InP tandem solar cells

    Science.gov (United States)

    Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

    1995-10-01

    Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

  13. Numerical Optimization of Tunnel-recombination Junction and Optical Absorption Properties of a-Si:H/a-SiGe:H Double-junction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    KE Shaoying; WANG Chong; PAN Tao; WANG Zhaoqing; YANG Jie; YANG Yu

    2015-01-01

    The tunnel-recombination junction (TRJ) and optical absorption properties of a-Si:H/a-SiGe:H dou-ble-junction solar cell were calculated by means of one dimensional simulator named AMPS-1D at the radiation of AM1.5G with a power density of 100 mW/cm2. Since the TRJ is the core component of the tandem solar cell, the optical absorption of the sub-cells and the electronic transport properties at the interface of the sub-cells are affected by the thickness and doping concentration of the TRJ. As a result, the TRJ parameters were optimized. The numerical results indicate that the maximum conversion efficiency (Ef) of 9.862% can be obtained when the thickness and doping con-centration of the TRJ are 10 nm and 5´1019 cm–3, respectively. Based on the analysis of the contour map of short circuit current density, the optimal current matching can be achieved for 130 nm-thick topi-layer and 250 nm-thick bottom i-layer. In addition, four kinds of TRJ structures were also simulated for the comparison purpose. According to the cal-culated resistivity and band structures of the four TRJs, the efficiency of the solar cell withn-typeμc-Si:H layer and p-type a-Si:H layer in TRJ structure is greater than that with other TRJ structures. It is assumed that the effect of the band offset that results in the formation of triangular barrier and backscattering behavior at the edge of the TRJ could be responsible to this phenomenon.

  14. Dimethylarsenic acid damages cellular DNA and inhibits gap junctional intercellular communication between human skin fibroblast cells

    Institute of Scientific and Technical Information of China (English)

    GuoXB; DengFR

    2002-01-01

    Although arsenic is identified as a human carcinogen,there is currently no accepted mechanism for its action or an established animal model for evaluating the carcinogenic activity of arsenic.To elucidate the mechanism of arsenic arcinogenesis,we investigated the effect of dimethylarsenic acid(DMAA),the main metabolite of inorganic arsenic in humans,on the cellular DNA and gap junctional intercellular communication (GJIC) between human skin fibroblast cells.Single-cell gel electrophoresis (SCGE) assay was used to detect the DNA damage in human skin fibroblast cells exposed to DMAA,and the GJIC between cells was detected by the scrape loading/dye transfer assay.DMAA at concentrations of 0.01-1.0 mmol·L-1 induced DNA damage in a dose-dependent manner,and GJIC between human skin fibroblast cells was significantly inhibited by DMAA at 1.0 mmol·L-1.Our results suggest that both genotoxic and nongenotoxic mechanism are involved in the mechanism of DMAA-induced cellular toxicity.

  15. Numerical study of metal oxide hetero-junction solar cells with defects and interface states

    International Nuclear Information System (INIS)

    Further to our previous work on ideal metal oxide (MO) hetero-junction solar cells, a systematic simulation has been carried out to investigate the effects of defects and interface states on the cells. Two structures of the window/absorber (WA) and window/absorber/voltage-enhancer (WAV) were modelled with defect concentration, defect energy level, interface state (ISt) density and ISt energy level as parameters. The simulation showed that the defects in the window layer and the voltage-enhancer layer have very limited effects on the performance of the cells, but those in the absorption layer have profound effects on the cell performance. The interface states at the W/A interface have a limited effect on the performance even for a density up to 1013 cm−2, while those at the A/V interface cause the solar cell to deteriorate severely even at a low density of lower than 1 × 1011 cm−2. It also showed that the back surface field (BSF) induced by band gap off-set in the WAV structure loses its function when defects with a modest concentration exist in the absorption layer and does not improve the open voltage at all. (paper)

  16. 17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures.

    Science.gov (United States)

    Lee, Kangmin; Hwang, Inchan; Kim, Namwoo; Choi, Deokjae; Um, Han-Don; Kim, Seungchul; Seo, Kwanyong

    2016-08-14

    We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm(2) exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm(-2) because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells. PMID:27405387

  17. Co-diffused back-contact back-junction silicon solar cells

    International Nuclear Information System (INIS)

    The driving force in photovoltaics is the reduction of the ratio between device costs and conversion efficiency. The present research study introduces a highly innovative diffusion process, called co-diffusion, which allows for a drastic decrease in process costs, on the one hand, and the assembly of a highly efficient solar cell device, the back-contact back-junction (BC-BJ) silicon solar cell, on the other. The co-diffusion approach is based on pre-patterned layers, which contain dopants, deposited by means of plasma enhanced chemical vapor deposition and diffusion in a tube furnace, which contains dopant gases in the process atmosphere. The solar cells are built on n-type silicon which features a high potential in achieving a high silicon life time, which is a necessary requirement of highly efficient BC-BJ solar cells. Fundamental knowledge in terms of co-diffusion processes can be gained from this research study. The processes allow for the fabrication of BC-BJ solar cell devices with a conversion efficiency exceeding 21 %.

  18. Development of a High Efficiency UVR/IRR Coverglass for Triple Junction Solar Cells

    Science.gov (United States)

    Russell, John; Jones, Glenn; Hall, James

    2007-01-01

    Cover glasses have been a necessary and integral part of space solar arrays since their inception. The main function of the cover glass is to protect the underlying solar cell from the harsh radiation environment of space. They are formed either from fused silica or specially formulated ceria doped glass types that are resistant to radiation damage, for example Pilkington's CMX, CMG, CMO. Solar cells have steadily increased in performance over the past years, from Silicon cells through textured Silicon cells to GaAs cells and the multijunction cells of today. The optimum coverglass solution for each of these cells has been different. The glass itself has also evolved. In some cases it has had its expansion coefficient matched to the cell substrate material, and in addition, added value has been derived from the application of thin film optical coatings to the coverglass. In the majority of cases this has taken the form of a single layer of MgF2 which acts as an antireflection coating. There are also conductive coatings to address electrostatic discharge issues (ESD) and Ultra Violet Reflective (UVR) and Infrared Reflective (IRR) coatings designed for thermal enhancement. Each type of coating can be applied singly or in combination. This paper describes a new type of UVR/IRR (or blue red reflector BRR) specifically designed for triple junction solar cells. For space applications, where radiation is the principal mechanism for removing heat from the satellite, it is the emittance and solar absorptance that primarily determine the temperature of the array. It is therefore essential that any coatings designed to have an effect on the temperature by reducing the solar absorption have a minimal effect on the overall emittance.

  19. Correlations between molecular structure and single-junction conductance: a case study with oligo(phenylene-ethynylene)-type wires.

    Science.gov (United States)

    Kaliginedi, Veerabhadrarao; Moreno-García, Pavel; Valkenier, Hennie; Hong, Wenjing; García-Suárez, Víctor M; Buiter, Petra; Otten, Jelmer L H; Hummelen, Jan C; Lambert, Colin J; Wandlowski, Thomas

    2012-03-21

    The charge transport characteristics of 11 tailor-made dithiol-terminated oligo(phenylene-ethynylene) (OPE)-type molecules attached to two gold electrodes were studied at a solid/liquid interface in a combined approach using an STM break junction (STM-BJ) and a mechanically controlled break junction (MCBJ) setup. We designed and characterized 11 structurally distinct dithiol-terminated OPE-type molecules with varied length and HOMO/LUMO energy. Increase of the molecular length and/or of the HOMO-LUMO gap leads to a decrease of the single-junction conductance of the linearly conjugate acenes. The experimental data and simulations suggest a nonresonant tunneling mechanism involving hole transport through the molecular HOMO, with a decay constant β = 3.4 ± 0.1 nm(-1) and a contact resistance R(c) = 40 kΩ per Au-S bond. The introduction of a cross-conjugated anthraquinone or a dihydroanthracene central unit results in lower conductance values, which are attributed to a destructive quantum interference phenomenon for the former and a broken π-conjugation for the latter. The statistical analysis of conductance-distance and current-voltage traces revealed details of evolution and breaking of molecular junctions. In particular, we explored the effect of stretching rate and junction stability. We compare our experimental results with DFT calculations using the ab initio code SMEAGOL and discuss how the structure of the molecular wires affects the conductance values. PMID:22352944

  20. Cost-effective platinum alloy counter electrodes for liquid-junction dye-sensitized solar cells

    Science.gov (United States)

    Li, Yanjuan; Tang, Qunwei; Yu, Liangmin; Yan, Xuefeng; Dong, Lei

    2016-02-01

    One of the challenges in developing advanced dye-sensitized solar cells (DSSCs) is the pursuit of cost-effective and robust counter electrodes (CEs). We present here the successful synthesis of binary PtxM100-x (M = Ni, Co, Fe) alloy nanostructures on Ti foil by a facile and environmental-friendly strategy for utilization as CEs in liquid-junction DSSCs. Due to the reasonable charge-transfer ability and excellent electrocatalytic activity, the resultant DSSC yields a promising power conversion efficiency (PCE) of 6.42% with binary Pt0.28Ni99.72 CE in comparison with 6.18% for pristine Pt CE based device. The easy synthesis, cost-effectiveness, and good electrocatalytic property may help the Pt0.28Ni99.72 nanostructure stand out as an alternative CE electrocatalyst in a DSSC.

  1. Operating limits of AL-alloyed high-low junctions for BSF solar cells

    Science.gov (United States)

    del Alamo, J.; Eguren, J.; Luque, A.

    1981-05-01

    Experimental estimations of the effective surface recombination velocity of the high-low junction and of the base diffusion length are carried out for Al-alloyed n(plus)pp(plus) bifacial cells and the results are presented in form of histograms. These results agree with calculated values of the effective surface recombination velocity when the characteristics of the recrystallized Si layer and heavy doping effects are taken into account. It is concluded that thick Al layers and high alloying temperatures (over 800 C) are necessary to obtain low values of the velocity. This conclusion agrees with experimental results of other authors. Recommendations to avoid diffusion length degradation are given and the operating limits of the Al alloying technology are discussed.

  2. Proton irradiation effects on amorphous silicon triple-junction solar cells

    International Nuclear Information System (INIS)

    Degradation behavior of a-Si/a-SiGe/a-SiGe triple-junction solar cells irradiated with various energy protons are investigated in-situ. It is clarified that the degradation due to proton irradiation is scaled by a unit of displacement damaged dose and thus the proton-induced degradation is mainly caused by the displacement damage effect. The performance recoveries immediately after irradiation are also investigated and it is clarified that all the parameters recover significantly at room temperature. In particular, the remarkable recovery is observed in the short-circuit current. This is thought to be due to recovery of the carrier lifetime, which is based on annealing of radiation defects. (author)

  3. Requirements for a GaAsBi 1 eV sub-cell in a GaAs-based multi-junction solar cell

    International Nuclear Information System (INIS)

    Multi-junction solar cells achieve high efficiency by stacking sub-cells of different bandgaps (typically GaInP/GaAs/Ge) resulting in efficiencies in excess of 40%. The efficiency can be improved by introducing a 1 eV absorber into the stack, either replacing Ge in a triple-junction configuration or on top of Ge in a quad-junction configuration. GaAs0.94Bi0.06 yields a direct-gap at 1 eV with only 0.7% strain on GaAs and the feasibility of the material has been demonstrated from GaAsBi photodetector devices. The relatively high absorption coefficient of GaAsBi suggests sufficient current can be generated to match the sub-cell photocurrent from the other sub-cells of a standard multi-junction solar cell. However, minority carrier transport and background doping levels place constraints on both p/n and p-i-n diode configurations. In the possible case of short minority carrier diffusion lengths we recommend the use of a p-i-n diode, and predict the material parameters that are necessary to achieve high efficiencies in a GaInP/GaAs/GaAsBi/Ge quad-junction cell. (paper)

  4. An Efficient Solution-Processed Intermediate Layer for Facilitating Fabrication of Organic Multi-Junction Solar Cells

    DEFF Research Database (Denmark)

    Ning Li; Baran, Derya; Forberich, Karen;

    2013-01-01

    ):poly(styrenesulfonate) (PEDOT:PSS) is demonstrated for series-connected multi-junction organic solar cells (OSCs). Drying at 80 °C in air is sufficient for this solution-processed IML to obtain excellent functionality and reliability, which allow the use of most of high performance donor materials in the tandem structure. An...

  5. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne;

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in...... extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx......43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium....

  6. Aluminum oxide passivated radial junction sub-micrometre pillar array textured silicon solar cells

    International Nuclear Information System (INIS)

    We report radial, p–n junction, sub-micrometre, pillar array textured solar cells, fabricated on an n-type Czochralski silicon wafer. Relatively simple processing schemes such as metal-assisted chemical etching and spin on dopant techniques were employed for the fabrication of the proposed solar cells. Atomic layer deposition (ALD) grown aluminum oxide (Al2O3) was employed as a surface passivation layer on the B-doped emitter surface. In spite of the fact that the sub-micrometre pillar array textured surface has a relatively high surface-to-volume ratio, we observed an open circuit voltage (VOC) and a short circuit current density (JSC) as high as 572 mV and 29.9 mA cm−2, respectively, which leads to a power conversion efficiency in excess of 11.30%, for the optimized structure of the solar cell described herein. Broadband omnidirectional antireflection effects along with the light trapping property of the sub-micrometre, pillar array textured surface and the excellent passivation quality of the ALD-grown Al2O3 on the B-doped emitter surface were responsible for the enhanced electrical performance of the proposed solar cells. (paper)

  7. Temperature increase in nanostructured cells of a magnetic tunnel junction during current-induced magnetization switching

    International Nuclear Information System (INIS)

    Three-dimensional numerical calculations based on the finite element method are performed to calculate the increase in the temperature in nanostructured cells of a magnetic tunnel junction under conditions that are relevant to current-induced magnetization switching for a high-density magnetic random access memory. Three key parameters, the lateral size, the resistance-area product and the applied current density, were varied widely so that their effects on the temperature increase could be examined. The computed results for the temperature increase, as a function of the resistance-area product and the current density, show the same trends that are expected from an equation for the dissipated heat. While the increase in the temperature is expected to be independent of the lateral size, the computations reveal a rather complicated relationship between the two variables, which is contingent on the various conditions that are considered. In a cell array that is relevant to high-density contexts, the temperature increase in the nearest cells is as high as 50% of the cell at which the current is directly applied; this could cause a thermal-stability problem in high-density magnetic random access memories. The temperature increase was also calculated under a more realistic physical picture of the relaxation of tunnelled electrons. These results are in agreement with those that are computed from Joule heating.

  8. Solar energy conversion through the interaction of plasmons with tunnel junctions. Part A: Solar cell analysis. Part B: Photoconductor analysis

    Science.gov (United States)

    Welsh, P. E.; Schwartz, R. J.

    1988-01-01

    A solar cell utilizing guided optical waves and tunnel junctions was analyzed to determine its feasibility. From this analysis, it appears that the limits imposed upon conventional multiple cell systems also limit this solar cell. Due to this limitation, it appears that the relative simplicity of the conventional multiple cell systems over the solar cell make the conventional multiple cell systems the more promising candidate for improvement. It was discovered that some superlattice structures studied could be incorporated into an infrared photodetector. This photoconductor appears to be promising as a high speed, sensitive (high D sup star sub BLIP) detector in the wavelength range from 15 to over 100 micrometers.

  9. Investigation of InGaP/(In)AlGaAs/GaAs triple-junction top cells for smart stacked multijunction solar cells grown using molecular beam epitaxy

    Science.gov (United States)

    Sugaya, Takeyoshi; Mochizuki, Toru; Makita, Kikuo; Oshima, Ryuji; Matsubara, Koji; Okano, Yoshinobu; Niki, Shigeru

    2015-08-01

    We report high-quality InGaP/(In)AlGaAs/GaAs triple-junction solar cells fabricated using solid-source molecular beam epitaxy (MBE) for the first time. The triple-junction cells can be used as top cells for smart stacked multijunction solar cells. A growth temperature of 480 °C was found to be suitable for an (In)AlGaAs second cell to obtain high-quality tunnel junctions. The properties of AlGaAs solar cells were better than those of InAlGaAs solar cells when a second cell was grown at 480 °C. The high-quality InGaP/AlGaAs/GaAs solar cell had an impressive open-circuit voltage of 3.1 V. This result indicates that high-performance InGaP/AlGaAs/GaAs triple-junction solar cells can be fabricated using solid-source MBE.

  10. The progress of large area GaInP2/GaAs/Ge triple junction cell development at Spectrolab

    Science.gov (United States)

    Chiang, P. K.; Krut, D.; Cavicchi, B. T.

    1995-01-01

    In this paper we report the successful fabrication of large area, monolithic triple junction, n on p, GaInP2/GaAs/Ge cells. The highest open circuit voltage and cell efficiency (cell area: 4.078 sq cm) were measured at 2.573 V and 23.3%, respectively, under 1 sun, AMO illumination. To our knowledge, this is the highest single crystal, monolithic, two terminal triple junction cell efficiency demonstrated. In addition, excellent uniformity across a 3 inch diameter Ge substrates has also been achieved. An average cell efficiency of 22.8% across the 3 inch diameter wafer has been measured. We have also successfully fabricated welded cell-interconnect-cover (CIC) assemblies using these triple junction devices. The highest CIC efficiency was 23.2% (bare cell efficiency was 23.3%). The average efficiency for 25 CICs was 21.8%, which is very comparable to the 22.0% average bare cell efficiency before they were fabricated into the CICs. Finally, we have measured temperature coefficient and 1 MeV electron irradiation data. These will be presented in the paper.

  11. Stat3 is a positive regulator of gap junctional intercellular communication in cultured, human lung carcinoma cells

    Directory of Open Access Journals (Sweden)

    Geletu Mulu

    2012-12-01

    Full Text Available Abstract Background Neoplastic transformation of cultured cells by a number of oncogenes such as src suppresses gap junctional, intercellular communication (GJIC; however, the role of Src and its effector Signal transducer and activator of transcription-3 (Stat3 upon GJIC in non small cell lung cancer (NSCLC has not been defined. Immunohistochemical analysis revealed high Src activity in NSCLC biopsy samples compared to normal tissues. Here we explored the potential effect of Src and Stat3 upon GJIC, by assessing the levels of tyr418-phosphorylated Src and tyr705-phosphorylated Stat3, respectively, in a panel of NSCLC cell lines. Methods Gap junctional communication was examined by electroporating the fluorescent dye Lucifer yellow into cells grown on a transparent electrode, followed by observation of the migration of the dye to the adjacent, non-electroporated cells under fluorescence illumination. Results An inverse relationship between Src activity levels and GJIC was noted; in five lines with high Src activity GJIC was absent, while two lines with extensive GJIC (QU-DB and SK-LuCi6 had low Src levels, similar to a non-transformed, immortalised lung epithelial cell line. Interestingly, examination of the mechanism indicated that Stat3 inhibition in any of the NSCLC lines expressing high endogenous Src activity levels, or in cells where Src was exogenously transduced, did not restore GJIC. On the contrary, Stat3 downregulation in immortalised lung epithelial cells or in the NSCLC lines displaying extensive GJIC actually suppressed junctional permeability. Conclusions Our findings demonstrate that although Stat3 is generally growth promoting and in an activated form it can act as an oncogene, it is actually required for gap junctional communication both in nontransformed lung epithelial cells and in certain lung cancer lines that retain extensive GJIC.

  12. Palladium nanoparticle array-mediated semiconductor bonding that enables high-efficiency multi-junction solar cells

    Science.gov (United States)

    Mizuno, Hidenori; Makita, Kikuo; Sugaya, Takeyoshi; Oshima, Ryuji; Hozumi, Yasuo; Takato, Hidetaka; Matsubara, Koji

    2016-02-01

    A detailed study on the application of Pd nanoparticle arrays, produced by self-assembled block copolymer templates, in bonding of III-V-based solar cell materials was carried out. The Pd nanoparticle array-mediated bonding (mechanical stacking) of GaAs-based thin-films (cells) was readily performed on the surface of GaAs or InP-based substrates (cells) to form multi-junction device architectures. Using the optimized Pd NP array, a 30.4%-efficiency four-junction two-terminal cell, consisting of an InGaP/GaAs top cell and an InGaAsP/InGaAs bottom cell, was achieved owing to the excellent electrical and optical bonding properties (bonding resistance, 1.81 Ω cm2; optical loss, 2.9%). Together with the verification of the long-term reliability of the Pd nanoparticle array-mediated bonding, our approach would become practically attractive for producing high-efficiency multi-junction solar cells.

  13. Glucocorticoids upregulates transepithelial electrical resistance and expression of tight junction-related protein in human trabecular meshwork cells

    Institute of Scientific and Technical Information of China (English)

    ZHUO Ye-hong; HUANG Ya-lin; WEI Yan-tao; LING Yun-lan; LIN Ming-kai; GE Jian

    2005-01-01

    @@ The trabecular meshwork is located at the anterior chamber angle, and is the main route for the outflow of aqueous humor. It is composed of perforated sheets of collagen and elastic tissue covered by trabecular meshwork (TM) cells, forming a filter with decreasing pore size as the canal of Schlemm is approached. TM cells have some endothelial properties, such as the presence of intercellular junctional complexes, particularly tight junctions (TJs). TJs form paracellular seals between adjacent cells and act as fences that segregate protein (and partially lipid) components of the apical and basolateral plasma membrane domains. Under the electron microscope, TJs appear as a series of discrete contacts between the lateral membranes of adjacent cells.

  14. TRAF4 is a novel phosphoinositide-binding protein modulating tight junctions and favoring cell migration.

    Directory of Open Access Journals (Sweden)

    Adrien Rousseau

    2013-12-01

    Full Text Available Tumor necrosis factor (TNF receptor-associated factor 4 (TRAF4 is frequently overexpressed in carcinomas, suggesting a specific role in cancer. Although TRAF4 protein is predominantly found at tight junctions (TJs in normal mammary epithelial cells (MECs, it accumulates in the cytoplasm of malignant MECs. How TRAF4 is recruited and functions at TJs is unclear. Here we show that TRAF4 possesses a novel phosphoinositide (PIP-binding domain crucial for its recruitment to TJs. Of interest, this property is shared by the other members of the TRAF protein family. Indeed, the TRAF domain of all TRAF proteins (TRAF1 to TRAF6 is a bona fide PIP-binding domain. Molecular and structural analyses revealed that the TRAF domain of TRAF4 exists as a trimer that binds up to three lipids using basic residues exposed at its surface. Cellular studies indicated that TRAF4 acts as a negative regulator of TJ and increases cell migration. These functions are dependent from its ability to interact with PIPs. Our results suggest that TRAF4 overexpression might contribute to breast cancer progression by destabilizing TJs and favoring cell migration.

  15. Effect of Chum Salmon Egg Lectin on Tight Junctions in Caco-2 Cell Monolayers

    Directory of Open Access Journals (Sweden)

    Ryo Nemoto

    2015-05-01

    Full Text Available The effect of a chum salmon egg lectin (CSL3 on tight junction (TJ of Caco-2 cell monolayers was investigated. The lectin opened TJ as indicated by the decrease of the transepithelial electrical resistance (TER value and the increase of the permeation of lucifer yellow, which is transported via the TJ-mediated paracellular pathway. The effects of CSL3 were inhibited by the addition of 10 mM L-rhamnose or D-galactose which were specific sugars for CSL3. The lectin increased the intracellular Ca2+ of Caco-2 cell monolayers, that could be inhibited by the addition of L-rhamnose. The fluorescence immunostaining of β-actin in Caco-2 cell monolayers revealed that the cytoskeleton was changed by the CSL3 treatment, suggesting that CSL3 depolymerized β-actin to cause reversible TJ structural and functional disruption. Although Japanese jack bean lectin and wheat germ lectin showed similar effects in the decrease of the TER values and the increase of the intracellular Ca2+, they could not be inhibited by the same concentrations of simple sugars, such as D-glucose and N-acetyl-D-glucosamine.

  16. Effect of chum salmon egg lectin on tight junctions in Caco-2 cell monolayers.

    Science.gov (United States)

    Nemoto, Ryo; Yamamoto, Shintaro; Ogawa, Tomohisa; Naude, Ryno; Muramoto, Koji

    2015-01-01

    The effect of a chum salmon egg lectin (CSL3) on tight junction (TJ) of Caco-2 cell monolayers was investigated. The lectin opened TJ as indicated by the decrease of the transepithelial electrical resistance (TER) value and the increase of the permeation of lucifer yellow, which is transported via the TJ-mediated paracellular pathway. The effects of CSL3 were inhibited by the addition of 10 mM L-rhamnose or D-galactose which were specific sugars for CSL3. The lectin increased the intracellular Ca2+ of Caco-2 cell monolayers, that could be inhibited by the addition of L-rhamnose. The fluorescence immunostaining of β-actin in Caco-2 cell monolayers revealed that the cytoskeleton was changed by the CSL3 treatment, suggesting that CSL3 depolymerized β-actin to cause reversible TJ structural and functional disruption. Although Japanese jack bean lectin and wheat germ lectin showed similar effects in the decrease of the TER values and the increase of the intracellular Ca2+, they could not be inhibited by the same concentrations of simple sugars, such as D-glucose and N-acetyl-D-glucosamine. PMID:25951005

  17. Arecoline induced disruption of expression and localization of the tight junctional protein ZO-1 is dependent on the HER 2 expression in human endometrial Ishikawa cells

    Directory of Open Access Journals (Sweden)

    Sundar Shyam N

    2010-07-01

    Full Text Available Abstract Background Approximately 600 million people chew Betel nut, making this practice the fourth most popular oral habit in the world. Arecoline, the major alkaloid present in betel nut is one of the causative agents for precancerous lesions and several cancers of mouth among those who chew betel nut. Arecoline can be detected in the human embryonic tissue and is correlated to low birth weight of newborns whose mothers chew betel nut during pregnancy, suggesting that arecoline can induce many systemic effects. However, few reports exist as to the effects of arecoline in human tissues other than oral cancer cell lines. Furthermore, in any system, virtually nothing is known about the cellular effects of arecoline treatment on membrane associated signaling components of human cancer cells. Results Using the human Ishikawa endometrial cancer cell line, we investigated the effects of arecoline on expression, localization and functional connections between the ZO-1 tight junction protein and the HER2 EGF receptor family member. Treatment of Ishikawa cells with arecoline coordinately down-regulated expression of both ZO-1 and HER2 protein and transcripts in a dose dependent manner. Biochemical fractionation of cells as well as indirect immunofluorescence revealed that arecoline disrupted the localization of ZO-1 to the junctional complex at the cell periphery. Compared to control transfected cells, ectopic expression of exogenous HER2 prevented the arecoline mediated down-regulation of ZO-1 expression and restored the localization of ZO-1 to the cell periphery. Furthermore, treatment with dexamethasone, a synthetic glucocorticoid reported to up-regulate expression of HER2 in Ishikawa cells, precluded arecoline from down-regulating ZO-1 expression and disrupting ZO-1 localization. Conclusion Arecoline is known to induce precancerous lesions and cancer in the oral cavity of betel nut users. The arecoline down-regulation of ZO-1 expression and

  18. Simulation of Hetero-junction (GaInP/GaAs Solar Cell Using AMPS-1D

    Directory of Open Access Journals (Sweden)

    Dennai Benmoussa

    2016-03-01

    Full Text Available Photovoltaic conversion is the direct conversion of electromagnetic energy into electrical energy continuously. This electromagnetic energy is the most solar radiation. In this work we performed a computer modelling using AMPS 1D optimization of hetero-junction solar cells GaInP / GaAs configuration for p/n. We studied the influence of the thickness the base layer in the cell offers on the open circuit voltage, the short circuit current and efficiency.

  19. Simulation of Hetero-junction (GaInP/GaAs) Solar Cell Using AMPS-1D

    OpenAIRE

    Dennai Benmoussa; M. Boukais; H. Benslimane

    2016-01-01

    Photovoltaic conversion is the direct conversion of electromagnetic energy into electrical energy continuously. This electromagnetic energy is the most solar radiation. In this work we performed a computer modelling using AMPS 1D optimization of hetero-junction solar cells GaInP / GaAs configuration for p/n. We studied the influence of the thickness the base layer in the cell offers on the open circuit voltage, the short circuit current and efficiency.

  20. Development of thin film amorphous silicon oxide/microcrystalline silicon double-junction solar cells and their temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Sriprapha, K.; Piromjit, C.; Limmanee, A.; Sritharathikhun, J. [Institute of Solar Energy Technology Development (SOLARTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

    2011-01-15

    We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (V{sub oc}), which are attractive for the use in high temperature environment. All p, i and n layers were deposited on transparent conductive oxide (TCO) coated glass substrate by a 60 MHz-very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. The p-i-n-p-i-n double-junction solar cells were fabricated by varying the CO{sub 2} and H{sub 2} flow rate of i top layer in order to obtain the wide bandgap with good quality material, which deposited near the phase boundary between a-SiO:H and hydrogenated microcrystalline silicon oxide ({mu}c-SiO:H), where the high V{sub oc} can be expected. The typical a-SiO:H/{mu}c-Si:H solar cell showed the highest initial cell efficiency of 10.5%. The temperature coefficient (TC) of solar cells indicated that the values of TC for conversion efficiency ({eta}) of the double-junction solar cells were inversely proportional to the initial V{sub oc}, which corresponds to the bandgap of the top cells. The TC for {eta} of typical a-SiO:H/{mu}c-Si:H was -0.32%/ C, lower than the value of conventional a-Si:H/{mu}c-Si:H solar cell. Both the a-SiO:H/{mu}c-Si:H solar cell and the conventional solar cell showed the same light induced degradation ratio of about 20%. We concluded that the solar cells using wide bandgap a-SiO:H film in the top cells are promising for the use in high temperature regions. (author)

  1. EFFECTS OF LIMONENE, SALVIA MILTIORRHIZA AND TURMERIC DERIVATIVES ON H-RAS ONCOGENE EXPRESSION AND GAP JUNCTION INTERCELLULAR COMMUNICATION IN HUMAN SOLID TUMOR CELL LINES

    Institute of Scientific and Technical Information of China (English)

    Chen Xiaoguang; Taday oshi Hasuma; Yoshihisa Yano; Toshiko Yoshimata; Hiyoshi Kamoi; Shuzo Otani

    1998-01-01

    Objective: To study gap junction intercellular communication (GJIC), H-ras oncogene expression and ras oncogene product (P21 ras protein) expression in four human solid tumor cell lines, W1-38, CACO2, A549 and PaCa, and the effects of four compounds, Salvia miltiorrhiza derivative (SMD), d-Limonene, Turmeric derivative Ⅰ (TD-Ⅰ) and Turmeric derivative Ⅱ (TD-Ⅱ), on them. Methods: The abilities of the four solid tumor cell lines to transfer dye to adjacent cells were examined by the scrape-loading/dye transfer technique, and the Hras oncogene expression by Northern blotting and P21 ras protein expression by Western blotting. Results: The results showed the loss of intercellular coupling in PaCa cells, slight GJIC in A549 and CACO2 cells, and a good GJIC in W1-38 cells. The four compounds could improve the GJIC of PaCa to different extents. The amount of total and membrane associated P21 ras in PaCa cells were decreased after treatment with SMD, d-Limonene and TD-Ⅰ (2.5 μg/ml) for 48 h. Concomitantly, the growth of PaCa cells decreased in soft agar and had enhanced GJIC.The relative potency was found to be:d-Limonene>SMD >TD-Ⅰ=TD-Ⅱ. There was no significant effect of the four compounds on H-ras oncogene expression. Conclusion:It was suggested that there was an excellent correlation between loss of Lucifer Yellow dye transfer and ras gene mutation rate in the four solid tumor cell lines (ras gene mutation rate inversely correlated with average cell number coupled, r=0.98) i.e., the high ras gene mutation was closely correlated with loss of GJIC in these malignant human tumor cells; The antitumor effect of the monoterpene d-Limonene and the phenol compound,SMD, might be related to inhibition of P21 ras membrane association and enhancement of GJIC, whilst that of the others may be by a different mechanism; The inhibition of p21 ras membrane association was directly related to the enhancement of gap junction intercellular communication.

  2. Cell communication across gap junctions: a historical perspective and current developments.

    Science.gov (United States)

    Evans, W Howard

    2015-06-01

    Collaborative communication lies at the centre of multicellular life. Gap junctions (GJs) are surface membrane structures that allow direct communication between cells. They were discovered in the 1960s following the convergence of the detection of low-resistance electrical interactions between cells and anatomical studies of intercellular contact points. GJs purified from liver plasma membranes contained a 27 kDa protein constituent; it was later named Cx32 (connexin 32) after its full sequence was determined by recombinant technology. Identification of Cx43 in heart and later by a further GJ protein, Cx26 followed. Cxs have a tetraspan organization in the membrane and oligomerize during intracellular transit to the plasma membrane; these were shown to be hexameric hemichannels (connexons) that could interact end-to-end to generate GJs at areas of cell-to-cell contact. The structure of the GJ was confirmed and refined by a combination of biochemical and structural approaches. Progress continues towards obtaining higher atomic 3D resolution of the GJ channel. Today, there are 20 and 21 highly conserved members of the Cx family in the human and mouse genomes respectively. Model organisms such as Xenopus oocytes and zebra fish are increasingly used to relate structure to function. Proteins that form similar large pore membrane channels in cells called pannexins have also been identified in chordates. Innexins form GJs in prechordates; these two other proteins, although functionally similar, are very different in amino acid sequence to the Cxs. A time line tracing the historical progression of wide ranging research in GJ biology over 60 years is mapped out. The molecular basis of channel dysfunctions in disease is becoming evident and progress towards addressing Cx channel-dependent pathologies, especially in ischaemia and tissue repair, continues. PMID:26009190

  3. The tight junction protein ZO-2 and Janus kinase 1 mediate intercellular communications in vascular smooth muscle cells

    International Nuclear Information System (INIS)

    Highlights: → The tight junction protein ZO-2 associates with Jak1 in vascular smooth muscle cells via ZO-2 N-terminal fragment. → Jak1 mediates ZO-2 tyrosine phosphorylation and ZO-2 localization to the sites of homotypic intercellular contacts. → The urokinase receptor uPAR regulates ZO-2/Jak1 functional association. → The ZO-2/Jak1/uPAR signaling complex is required for vascular smooth muscle cells functional network formation. -- Abstract: Recent evidence points to a multifunctional role of ZO-2, the tight junction protein of the MAGUK (membrane-associated guanylate kinase-like) family. Though ZO-2 has been found in cell types lacking tight junction structures, such as vascular smooth muscle cells (VSMC), little is known about ZO-2 function in these cells. We provide evidence that ZO-2 mediates specific homotypic cell-to-cell contacts between VSMC. Using mass spectrometry we found that ZO-2 is associated with the non-receptor tyrosine kinase Jak1. By generating specific ZO-2 constructs we further found that the N-terminal fragment of ZO-2 molecule is responsible for this interaction. Adenovirus-based expression of Jak1 inactive mutant demonstrated that Jak1 mediates ZO-2 tyrosine phosphorylation. By means of RNA silencing, expression of Jak1 mutant form and fluorescently labeled ZO-2 fusion protein we further specified that active Jak1, but not Jak1 inactive mutant, mediates ZO-2 localization to the sites of intercellular contacts. We identified the urokinase receptor uPAR as a pre-requisite for these cellular events. Functional requirement of the revealed signaling complex for VSMC network formation was confirmed in experiments using Matrigel and in contraction assay. Our findings imply involvement of the ZO-2 tight junction independent signaling complex containing Jak1 and uPAR in VSMC intercellular communications. This mechanism may contribute to vascular remodeling in occlusive cardiovascular diseases and in arteriogenesis.

  4. The tight junction protein ZO-2 and Janus kinase 1 mediate intercellular communications in vascular smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Tkachuk, Natalia; Tkachuk, Sergey; Patecki, Margret [Department of Nephrology, Hannover Medical School, Hannover D-30625 (Germany); Kusch, Angelika [Department of Nephrology and Intensive Care Medicine, Charite Campus Virchow-Klinikum, Berlin D-13353 (Germany); Korenbaum, Elena; Haller, Hermann [Department of Nephrology, Hannover Medical School, Hannover D-30625 (Germany); Dumler, Inna, E-mail: dumler.inna@mh-hannover.de [Department of Nephrology, Hannover Medical School, Hannover D-30625 (Germany)

    2011-07-08

    Highlights: {yields} The tight junction protein ZO-2 associates with Jak1 in vascular smooth muscle cells via ZO-2 N-terminal fragment. {yields} Jak1 mediates ZO-2 tyrosine phosphorylation and ZO-2 localization to the sites of homotypic intercellular contacts. {yields} The urokinase receptor uPAR regulates ZO-2/Jak1 functional association. {yields} The ZO-2/Jak1/uPAR signaling complex is required for vascular smooth muscle cells functional network formation. -- Abstract: Recent evidence points to a multifunctional role of ZO-2, the tight junction protein of the MAGUK (membrane-associated guanylate kinase-like) family. Though ZO-2 has been found in cell types lacking tight junction structures, such as vascular smooth muscle cells (VSMC), little is known about ZO-2 function in these cells. We provide evidence that ZO-2 mediates specific homotypic cell-to-cell contacts between VSMC. Using mass spectrometry we found that ZO-2 is associated with the non-receptor tyrosine kinase Jak1. By generating specific ZO-2 constructs we further found that the N-terminal fragment of ZO-2 molecule is responsible for this interaction. Adenovirus-based expression of Jak1 inactive mutant demonstrated that Jak1 mediates ZO-2 tyrosine phosphorylation. By means of RNA silencing, expression of Jak1 mutant form and fluorescently labeled ZO-2 fusion protein we further specified that active Jak1, but not Jak1 inactive mutant, mediates ZO-2 localization to the sites of intercellular contacts. We identified the urokinase receptor uPAR as a pre-requisite for these cellular events. Functional requirement of the revealed signaling complex for VSMC network formation was confirmed in experiments using Matrigel and in contraction assay. Our findings imply involvement of the ZO-2 tight junction independent signaling complex containing Jak1 and uPAR in VSMC intercellular communications. This mechanism may contribute to vascular remodeling in occlusive cardiovascular diseases and in arteriogenesis.

  5. Equivalent electron fluence for solar proton damage in GaAs shallow junction cells

    Science.gov (United States)

    Wilson, J. W.; Stock, L. V.

    The short-circuit current reduction in GaAs shallow junction heteroface solar cells was calculated according to a simplified solar cell damage model in which the nonuniformity of the damage as a function of penetration depth is treated explicitly. Although the equivalent electron fluence was not uniquely defined for low-energy monoenergetic proton exposure, an equivalent electron fluence is found for proton spectra characteristic of the space environment. The equivalent electron fluence ratio was calculated for a typical large solar flare event for which the proton spectrum is PHI(sub p)(E) = A/E(p/sq. cm) where E is in MeV. The equivalent fluence ratio is a function of the cover glass shield thickness or the corresponding cutoff energy E(sub c). In terms of the cutoff energy, the equivalent 1 MeV electron fluence ratio is r(sub p)(E sub c) = 10(9)/E(sub c)(1.8) where E(sub c) is in units of KeV.

  6. Corrective transduction of human epidermal stem cells in laminin-5-dependent junctional epidermolysis bullosa.

    Science.gov (United States)

    Dellambra, E; Vailly, J; Pellegrini, G; Bondanza, S; Golisano, O; Macchia, C; Zambruno, G; Meneguzzi, G; De Luca, M

    1998-06-10

    Laminin-5 is composed of three distinct polypeptides, alpha3, beta3, and gamma2, which are encoded by three different genes, LAMA3, LAMB3, and LAMC2, respectively. We have isolated epidermal keratinocytes from a patient presenting with a lethal form of junctional epidermolysis bullosa characterized by a homozygous mutation of the LAMB3 gene, which led to complete absence of the beta3 polypeptide. In vitro, beta3-null keratinocytes were unable to synthesize laminin-5 and to assemble hemidesmosomes, maintained the impairment of their adhesive properties, and displayed a decrease of their colony-forming ability. A retroviral construct expressing a human beta3 cDNA was used to transduce primary beta3-null keratinocytes. Clonogenic beta3-null keratinocytes were transduced with an efficiency of 100%. Beta3-transduced keratinocytes were able to synthesize and secrete mature heterotrimeric laminin-5. Gene correction fully restored the keratinocyte adhesion machinery, including the capacity of proper hemidesmosomal assembly, and prevented the loss of the colony-forming ability, suggesting a direct link between adhesion to laminin-5 and keratinocyte proliferative capacity. Clonal analysis demonstrated that holoclones expressed the transgene permanently, suggesting stable correction of epidermal stem cells. Because cultured keratinocytes are used routinely to make autologous grafts for patients suffering from large skin or mucosal defects, the full phenotypic reversion of primary human epidermal stem cells defective for a structural protein opens new perspectives in the long-term treatment of genodermatoses. PMID:9650620

  7. The effect of the optical system on the electrical performance of III-V concentrator triple junction solar cells

    Science.gov (United States)

    Schultz, R. D.; van Dyk, E. E.; Vorster, F. J.

    2016-01-01

    High Concentrated Photovoltaic (H-CPV) technologies utilize relatively inexpensive reflective and refractive optical components for concentration to achieve high energy yield. The electrical performance of H-CPV systems is, however, dependent on the properties and configuration of the optical components. The focus of this paper is to summarize the effect of the properties of the optical system on the electrical performance of a Concentrator Triple Junction (CTJ) InGaP/InGaAs/Ge cell. Utilizing carefully designed experiments that include spectral measurements and intensity profiles in the optical plane of the CTJ cell, the influence of photon absorption, Fresnel lens properties and chromatic aberration created by the optical system on the electrical performance of a CTJ cell is shown. From the results obtained, it is concluded that good characterization and understanding of the optical system's properties may add to improved design of future multi-junction devices.

  8. Functional chromaffin cell plasticity in response to stress: focus on nicotinic, gap junction, and voltage-gated Ca2+ channels.

    Science.gov (United States)

    Guérineau, Nathalie C; Desarménien, Michel G; Carabelli, Valentina; Carbone, Emilio

    2012-10-01

    An increase in circulating catecholamines constitutes one of the mechanisms whereby human body responds to stress. In response to chronic stressful situations, the adrenal medullary tissue exhibits crucial morphological and functional changes that are consistent with an improvement of chromaffin cell stimulus-secretion coupling efficiency. Stimulus-secretion coupling encompasses multiple intracellular (chromaffin cell excitability, Ca(2+) signaling, exocytosis, endocytosis) and intercellular pathways (splanchnic nerve-mediated synaptic transmission, paracrine and endocrine communication, gap junctional coupling), each of them being potentially subjected to functional remodeling upon stress. This review focuses on three chromaffin cell incontrovertible actors, the cholinergic nicotinic receptors and the voltage-dependent T-type Ca(2+) channels that are directly involved in Ca(2+)-dependent events controlling catecholamine secretion and electrical activity, and the gap junctional communication involved in the modulation of catecholamine secretion. We show here that these three actors react differently to various stressors, sometimes independently, sometimes in concert or in opposition. PMID:22252244

  9. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    Science.gov (United States)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells. PMID:26061271

  10. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance.

    Science.gov (United States)

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current-voltage (I-V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I-V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research. PMID:27455067

  11. Estrogenic compounds inhibit gap junctional intercellular communication in mouse Leydig TM3 cells

    International Nuclear Information System (INIS)

    Some estrogenic compounds are reported to cause testicular disorders in humans and/or experimental animals by direct action on Leydig cells. In carcinogenesis and normal development, gap junctional intercellular communication (GJIC) plays an essential role in maintaining homeostasis. In this study, we examine the effects of diethylstilbestrol (DES, a synthetic estrogen), 17β-estradiol (E2, a natural estrogen), and genistein (GEN, a phytoestrogen) on GJIC between mouse Leydig TM3 cells using Lucifer yellow microinjection. The three compounds tested produced GJIC inhibition in the TM3 cells after 24 h. Gradually, 10 μM DES began to inhibit GJIC for 24 h and this effect was observed until 72 h. On the other hand, both 20 μM E2 and 25 μM GEN rapidly inhibited GJIC in 6 h and 2 h, respectively. The effects continued until 24 h, but weakened by 72 h. Furthermore, a combined effect at μM level between DES and E2 on GJIC inhibition was observed, but not between GEN and E2. DES and E2 showed GJIC inhibition at low dose levels (nearly physiological estrogen levels) after 72 h, but GEN did not. DES-induced GJIC inhibition at 10 pM and 10 μM was completely counteracted by ICI 182,780 (ICl), an estrogen receptor antagonist. On the other hand, the inhibitory effects on GJIC with E2 (10 pM and 20 μM) and GEN (25 μM) were partially blocked by ICI or calphostin C, a protein kinase C (PKC) inhibitor, and were completely blocked by the combination of ICI and calphostin C. These results demonstrate that DES inhibits GJIC between Leydig cells via the estrogen receptor (ER), and that E2 and GEN inhibit GJIC via ER and PKC. These estrogenic compounds may have different individual nongenotoxic mechanism including PKC pathway on testicular carcinogenesis or development

  12. Oxygen modulation of flexible PbS/Pb Schottky junction PEC cells with improved photoelectric performance

    Science.gov (United States)

    Wang, Peng; Fan, Libo; Guo, Qiuquan; Shi, Hongcai; Wang, Liwen; Liu, Yujian; Li, Ming; Zhang, Chunli; Yang, Jun; Zheng, Zhi

    2016-09-01

    Flexible photoelectric devices are emerging as a new class of photovoltaic cells. In this study, lead (Pb) foil was used as a flexible substrate to grow in situ lead sulfide (PbS) film with good uniformity and adhesion by a solvothermal elemental direct reaction, resulting in a PbS/Pb Schottky junction formed naturally between the PbS film and underlying Pb foil. We found that the photocurrent response of the photoelectrochemical (PEC) cell was greatly improved through a facile oxygen (O2)-modulation-based post-processing technique. O2 could decompose the organic residue and oxidize the Pb at the interface between the PbS film and Pb foils. Different characterization techniques, including thermogravimetric analysis, differential scanning calorimetry, x-ray diffraction, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, the change in transient photocurrent density (J p) with time (t), dark current–voltage (I–V) and absorption spectra were applied to get a full understanding of the O2 modulation effect. The oxidization treatment of the PbS film could regulate the flow of charge carriers to reduce their recombination, leading to photoresponse enhancement for the PEC cells. In particular, the process could modulate the tunneling current and interface states to optimize dark I–V characteristics. In addition, the magnitude of the barrier height can be tuned by O2 modulation, which was explained by theoretical analysis and calculation. We also demonstrated that the in situ formed PbS film has outstanding adhesion on the flexible Pb substrate. Our film synthesis method and post O2-modulation design as well as the corresponding device assembly may provide a novel perspective to the flexible PCE-cell-related research.

  13. Optimization of Recombination Layer in the Tunnel Junction of Amorphous Silicon Thin-Film Tandem Solar Cells

    OpenAIRE

    Yang-Shin Lin; Shui-Yang Lien; Chao-Chun Wang; Chia-Hsun Hsu; Chih-Hsiang Yang; Asheesh Nautiyal; Dong-Sing Wuu; Pi-Chuen Tsai; Shuo-Jen Lee

    2011-01-01

    The amorphous silicon/amorphous silicon (a-Si/a-Si) tandem solar cells have attracted much attention in recent years, due to the high efficiency and low manufacturing cost compared to the single-junction a-Si solar cells. In this paper, the tandem cells are fabricated by high-frequency plasma-enhanced chemical vapor deposition (HF-PECVD) at 27.1 MHz. The effects of the recombination layer and the i-layer thickness matching on the cell performance have been investigated. The results show that ...

  14. Origin of correlated activity between parasol retinal ganglion cells.

    Science.gov (United States)

    Trong, Philipp Khuc; Rieke, Fred

    2008-11-01

    Cells throughout the CNS have synchronous activity patterns; that is, a cell's probability of generating an action potential depends both on its firing rate and on the occurrence of action potentials in surrounding cells. The mechanisms producing synchronous or correlated activity are poorly understood despite its prevalence and potential effect on neural coding. We found that neighboring parasol ganglion cells in primate retina received strongly correlated synaptic input in the absence of modulated light stimuli. This correlated variability appeared to arise through the same circuits that provide uncorrelated synaptic input. In addition, ON, but not OFF, parasol cells were coupled electrically. Correlated variability in synaptic input, however, dominated correlations in the parasol spike outputs and shared variability in the timing of action potentials generated by neighboring cells. These results provide a mechanistic picture of how correlated activity is produced in a population of neurons that are critical for visual perception. PMID:18820692

  15. Triple-junction thin-film silicon solar cell fabricated on periodically textured substrate with a stabilized efficiency of 13.6%

    Science.gov (United States)

    Sai, Hitoshi; Matsui, Takuya; Koida, Takashi; Matsubara, Koji; Kondo, Michio; Sugiyama, Shuichiro; Katayama, Hirotaka; Takeuchi, Yoshiaki; Yoshida, Isao

    2015-05-01

    We report a high-efficiency triple-junction thin-film silicon solar cell fabricated with the so-called substrate configuration. It was verified whether the design criteria for developing single-junction microcrystalline silicon (μc-Si:H) solar cells are applicable to multijunction solar cells. Furthermore, a notably high short-circuit current density of 32.9 mA/cm2 was achieved in a single-junction μc-Si:H cell fabricated on a periodically textured substrate with a high-mobility front transparent contacting layer. These technologies were also combined into a-Si:H/μc-Si:H/μc-Si:H triple-junction cells, and a world record stabilized efficiency of 13.6% was achieved.

  16. High-field domains in CdS adjacent to a junction of p-type solar cells

    Science.gov (United States)

    Böer, Karl W.

    2016-02-01

    A thin cover layer (150 Å preferred) of copper-doped CdS, when applied on top of any p-type solar cell, can connect this cell directly to an electron-blocking electrode without a pn-junction and increases the open circuit voltage close to its theoretical value; in the example of a CdS/CdTe cell, it increases Voc to its extrapolated value at T = 0 K of the band gap of 1.45 eV. This is caused by a high-field domain that is attached to the junction and limits the field to below tunneling to prevent junction leakage and connects to the CdS that has turned p-type. The large Debye length exceeding the thickness of the CdS forces a direct connection to the electron-blocking cathode with holes tunneling into the metal. The difference of junction-attached high-field domains to the electrode-attached domains, which were described earlier, are given and the consequences are delineated by increasing the conversion efficiency from 8% to 16% in CdTe, while also causing some series resistance limitation. The effect of the added CdS layer is discussed by drawing a to-scale model of the CdS/CdTe solar cell from all experimentally available data and the assumption of the continuity of the hole current. A small jump of the valence band downward is caused by interface recombination. The assistance of high-field domains in CdS is also exemplified by the results of an extremely simple production procedure of the CdS/Cu2S solar cells.

  17. Calcium-mediated transductive systems and functionally active gap junctions in astrocyte-like GL15 cells

    Directory of Open Access Journals (Sweden)

    Steimberg Nathalie

    2001-05-01

    Full Text Available Abstract Background It has been proposed that GL15, a human cell line derived from glioblastoma multiforme, is a possible astroglial-like cell model, based on the presence of cytoplasmic glial fibrillary acidic protein. Results The aim of this work was to delineate the functional characteristics of GL15 cells using various experimental approaches, including the study of morphology, mechanism of induction of intracellular Ca2+ increase by different physiological agonists, and the presence and permeability of the gap-junction system during cell differentiation. Immunostaining experiments showed the presence and localization of specific glial markers, such as glial fibrillary acidic protein and S100B, and the lack of the neuronal marker S100A. Notably, all the Ca2+ pathways present in astrocytes were detected in GL15 cells. In particular, oscillations in intracellular Ca2+ levels were recorded either spontaneously, or in the presence of ATP or glutamate (but not KCl. Immunolabelling assays and confocal microscopy, substantiated by Western blot analyses, revealed the presence of connexin43, a subunit of astrocyte gap-junction channels. The protein is organised in characteristic spots on the plasma membrane at cell-cell contact regions, and its presence and distribution depends on the differentiative status of the cell. Finally, a microinjection/dye-transfer assay, employed to determine gap-junction functionality, clearly demonstrated that the cells were functionally coupled, albeit to varying degrees, in differentiated and undifferentiated phenotypes. Conclusions In conclusion, results from this study support the use of the GL15 cell line as a suitable in vitro astrocyte model, which provides a valuable guide for studying glial physiological features at various differentiation phases.

  18. Sensory transduction at the frog semicircular canal: how hair cell membrane potential controls junctional transmission.

    Directory of Open Access Journals (Sweden)

    Riccardo Fesce

    2015-06-01

    Full Text Available At the frog semicircular canals, the afferent fibers display high spontaneous activity (mEPSPs, due to transmitter release from hair cells. mEPSP and spike frequencies are modulated by stimulation that activates the hair cell receptor conductance. The relation between receptor current and transmitter release cannot be studied at the intact semicircular canal. To circumvent the problem, we combined patch-clamp recordings at the isolated hair cell and electrophysiological recordings at the cytoneural junction in the intact preparation. At isolated hair cells, the K channel blocker TEA is shown to block a fraction of total voltage-dependent K-conductance (IKD that depends on TEA concentration but not on membrane potential (Vm. Considering the bioelectric properties of the hair cell, as previously characterized by this lab, a fixed fractional block of IKD is shown to induce a relatively fixed shift in Vm, provided it lies in the range -30 to -10 mV. The same concentrations of TEA were applied to the intact labyrinth while recording from single afferent fibers of the posterior canal, at rest and during mechanical stimulation. At the peak of stimulation, TEA produced increases in mEPSP rate that were linearly related to the shifts produced by the same TEA concentrations (0.1-3 mM in hair cell Vm (0.7-5 mV, with a slope of 29.8 Hz/mV. The membrane potential of the hair cell is not linearly related to receptor conductance, so that the slope of quantal release vs. receptor conductance depends on the prevailing Vm (19.8 Hz/nS at -20 mV; 11 Hz/nS at -10 mV. Changes in mEPSP peak size were negligible at rest as well as during stimulation. Since ample spatial summation of mEPSPs occurs at the afferent terminal and threshold-governed spike firing is intrinsically nonlinear, the observed increases in mEPSP frequency, though not very large, may suffice to trigger afferent spike discharge.

  19. Evaluation of InGaP/InGaAs/Ge triple-junction solar cell and optimization of solar cell's structure focusing on series resistance for high-efficiency concentrator photovoltaic systems

    OpenAIRE

    Nishioka, K.; Takamoto, T; Agui, T; Kaneiwa, M; Uraoka, Y.; Fuyuki, T

    2006-01-01

    The series resistance of an InGaP/InGaAs/Ge triple-junction solar cell was evaluated in detail. Series resistance components such as electrode resistance, tunnel junction resistance and lateral resistance between electrodes were estimated separately. The characteristics of the triple-junction solar cell under concentrated light were evaluated by equivalent circuit calculation with a simulation program with integrated circuit emphasis (SPICE). By equivalent circuit calculation, the optimizatio...

  20. Hot Wire CVD for thin film triple junction cells and for ultrafast deposition of the SiN passivation layer on polycrystalline Si solar cells

    OpenAIRE

    Schropp, R.E.I.; Franken, R.H.; Goldbach, H.D.; Houweling, Z.S.; Li, H. B. T.; J.K. Rath; Schuttauf, J.A.; Stolk, R.L.; Verlaan, V.; van der Werf, C.H.M.

    2008-01-01

    We present recent progress on hot-wire deposited thin film solar cells and applications of silicon nitride. The cell efficiency reached for μc-Si:H n–i–p solar cells on textured Ag/ZnO presently is 8.5%, in line with the state-of-the-art level for μc-Si:H n–i–p's for any method of deposition. Such cells, used in triple junction cells together with hot-wire deposited proto-Si:H and plasma-deposited SiGe:H, have reached 10.5% efficiency. The single junction μc-Si:H n–i–p cell is entirely stable...

  1. The behavior of series resistance of a p-n junction: the diode and the solar cell cases

    Science.gov (United States)

    Bueno, Poliana H.; Costa, Diogo F.; Eick, Alexander; Carvalho, André; Monteiro, Davies W. L.

    2016-03-01

    This paper presents a comparison of the impact of the internal parasitic series resistance of a p-n junction, as seen from the microelectronics and photovoltaic communities. The elusive thermal behavior of the aforementioned resistance gave this work its origin. Each community uses a different approach to interpret the operational current-voltage behavior of a p-n junction, which might lead to confusion, since scientists and engineers of these two realms seldom interact. An improvement in the understanding of the different approaches will help one to better model the performance of devices based on p-n junctions and therefore it will favor the performance predictions of photovoltaic cells. For diodes, series resistance is usually determined from a specific forward-bias region of the I-V curve on a semi-logarithmic scale. However, in Photovoltaics this region is not commonly reported and therefore other methods to determine Rs are employed. We mathematically modeled an experimentally obtained I-V curve with various pairs of the ideality factor and Rs and found that more than one pair accurately synthesizes the measured curve. We can conclude that the reported series resistance not only depends on physical parameters, e.g. temperature or irradiance, but also on fitting parameters, i.e. the ideality factor. Generally the behavior of a p-n junction depends on its operating conditions and electrical modeling.

  2. Effects of Different Solvents on the Planar Hetero-junction Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Lin Shunquan

    2015-01-01

    Full Text Available The perovskite (CH3NH3PbI3 films on the planar hetero-junction perovskite solar cells (PHJ-PSCs are fabricated by “two-steps” process with the wet spin-coating method. The precursor (PbI2 solutions are compounded with 4 types of solvents: N-Methyl Pyrrolidone (NMP, γ-butyrolactone (GBL, Dimethyl Sulfoxide (DMSO and N, N-dimethylformamide (DMF. All the solutions have the same concentration. The influences of different precursor solvents to the micro-structures of CH3NH3PbI3 films and device performance are studied. Atomic force microscopy (AFM and scanning electron microscope (SEM are used to characterize the CH3NH3PbI3 films. The results indicate that the CH3NH3PbI3 film using DMF solvent possesses more rough morphology and thickest thickness. The monolithic PHJ-PSCs devices based on DMF solvent are tested under a standard one sun of simulated solar irradiation (AM1.5. The results show that the open-circuit voltage (Voc reaches 872mV, the short-circuit current (Jsc reaches 9.35mA/cm2, the filling factor(FF is 0.62 and the photo-current conversion efficiency (PCE is 5.05%. DMF is the best one among these 4 types of solvents for PHJ-PSCs.

  3. Doping Evolution and Junction Formation in Stacked Cyanine Dye Light-Emitting Electrochemical Cells.

    Science.gov (United States)

    Jenatsch, Sandra; Wang, Lei; Bulloni, Matia; Véron, Anna C; Ruhstaller, Beat; Altazin, Stéphane; Nüesch, Frank; Hany, Roland

    2016-03-16

    Cyanine dyes are fluorescent organic salts with intrinsic conductivity for ionic and electronic charges. Recently ( J. Am. Chem. Soc. 2013 , 135 , 18008 - 18011 ), these features have been exploited in cyanine light-emitting electrochemical cells (LECs). Here, we demonstrate that stacked, constant-voltage driven trimethine cyanine LECs with various counteranions develop a p-i-n junction that is composed of p- and n-doped zones and an intrinsic region where light-emission occurs. We introduce a method that combines spectral photocurrent response measurements with optical modeling and find that at maximum current the intrinsic region is centered at ∼37% away from the anode. Transient capacitance, photoluminescence and attenuance experiments indicate a device situation with a narrow p-doped region, an undoped region that occupies ∼72% of the dye layer thickness and an n-doped region with a maximum doping concentration of 0.08 dopant/cyanine molecule. Finally, we observe that during device relaxation the parent cyanines are not reformed. We ascribe this to irreversible reactions between doped cyanine radicals. For sterically conservative cyanine dyes, this suggests that undesired radical decomposition pathways limit the LEC long-term stability in general. PMID:26914281

  4. Mechanically Stacked Triple-junction GaInP / GaAs / Si Solar Cell Simulation

    Directory of Open Access Journals (Sweden)

    A.B. Gnilenko

    2014-01-01

    Full Text Available Mechanically stacked triple-junction GaInP / GaAs / Si solar cell is simulated by Silvaco TCAD computer software and compared to more conventional GaInP / GaAs / Ge mechanically stacked configuration. External quantum efficiency, I-V characteristics and basic I-V parameters are obtained to demonstrate the advantages of using the silicon active substrate as the bottom sub-cell instead of the germanium substrate based bottom sub-cell.

  5. INHIBITION OF GAP JUNCTIONAL INTERCELLULAR COMMUNICATION BY PERFLUORINATED COMPOUNDS IN RAT LIVER AND DOLPHIN KIDNEY EPITHELIAL CELL LINES IN VITRO AND SPRAGUE-DAWLEY RATS IN VIVO

    Science.gov (United States)

    Abstract Gap Junctional Intercellular Communication (GJIC) is the major pathway of intercellular signal transduction, and is, thus, important for normal cell growth and function. Recent studies have revealed a global distribution of some perfluorinated organic compounds e...

  6. Concept of Recombination Velocity Sfcc at the Junction of a Bifacial Silicon Solar Cell, in Steady State, Initiating the Short-Circuit Condition

    Directory of Open Access Journals (Sweden)

    I.ly

    2013-01-01

    Full Text Available The aim of this study is to present technics to determine the junction recombination velocity of a bifacial polycrystalline silicon solar cell under both, constant multispectral illumination and steady short-circuit condition.

  7. Concept of Recombination Velocity Sfcc at the Junction of a Bifacial Silicon Solar Cell, in Steady State, Initiating the Short-Circuit Condition

    OpenAIRE

    I. Ly; NDiaye, M; G. Sissoko; Wade, M.; Ndeye Thiam; Sega Gueye

    2013-01-01

    The aim of this study is to present technics to determine the junction recombination velocity of a bifacial polycrystalline silicon solar cell under both, constant multispectral illumination and steady short-circuit condition.

  8. The Loss of Cellular Junctions in Epithelial Lung Cells Induced by Cigarette Smoke Is Attenuated by Corilagin

    Directory of Open Access Journals (Sweden)

    Ximena M. Muresan

    2015-01-01

    Full Text Available Cigarette smoke (CS contains over 4700 compounds, many of which can affect cellular redox balance through free radicals production or through the modulation of antioxidant enzymes. The respiratory tract is one of the organs directly exposed to CS and it is known that CS can damage the integrity of lung epithelium by affecting cell junctions and increasing epithelium permeability. In this study, we have used a human lung epithelial cell line, Calu-3, to evaluate the effect of CS on lung epithelial cell junctions levels, with special focus on the expression of two proteins involved in intercellular communication: connexins (Cx 40 and 43. CS exposure increased Cx40 gene expression but not of Cx43. CS also induced NFκB activation and the formation of 4HNE-Cxs adducts. Since corilagin, a natural polyphenol, is able to inhibit NFκB activation, we have determined whether corilagin could counteract the effect of CS on Cxs expression. Corilagin was able to diminish CS induced Cx40 gene expression, 4HNE-Cx40 adducts formation, and NFκB activation. The results of this study demonstrated that CS induced the loss of cellular junctions in lung epithelium, possibly as a consequence of Cx-4HNE adducts formation, and corilagin seems to be able to abolish these CS induced alterations.

  9. HDAC inhibition amplifies gap junction communication in neural progenitors: Potential for cell-mediated enzyme prodrug therapy

    International Nuclear Information System (INIS)

    Enzyme prodrug therapy using neural progenitor cells (NPCs) as delivery vehicles has been applied in animal models of gliomas and relies on gap junction communication (GJC) between delivery and target cells. This study investigated the effects of histone deacetylase (HDAC) inhibitors on GJC for the purpose of facilitating transfer of therapeutic molecules from recombinant NPCs. We studied a novel immortalized midbrain cell line, NGC-407 of embryonic human origin having neural precursor characteristics, as a potential delivery vehicle. The expression of gap junction protein connexin 43 (C x 43) was analyzed by western blot and immunocytochemistry. While C x 43 levels were decreased in untreated differentiating NGC-407 cells, the HDAC inhibitor 4-phenylbutyrate (4-PB) increased C x 43 expression along with increased membranous deposition in both proliferating and differentiating cells. Simultaneously, Ser 279/282-phosphorylated form of C x 43 was declined in both culture conditions by 4-PB. The 4-PB effect in NGC-407 cells was verified by using HNSC.100 human neural progenitors and Trichostatin A. Improved functional GJC is of imperative importance for therapeutic strategies involving intercellular transport of low molecular-weight compounds. We show here an enhancement by 4-PB, of the functional GJC among NGC-407 cells, as well as between NGC-407 and human glioma cells, as indicated by increased fluorescent dye transfer

  10. Quantum breathers in small networks: dynamics, tunneling, correlations, and application to Josephson cells

    International Nuclear Information System (INIS)

    We address the excitation of quantum breathers in small nonlinear networks of two and three degrees of freedom, in order to study their properties. The invariance under permutation of two sites of these networks substitutes the translation invariance that is present in nonlinear lattices, where (classical) discrete breathers are time periodic space localized solutions of the underlying classical equations of motion. We do a systematic analysis of the spectrum and eigenstates of such small systems, characterizing quantum breather states by their tunneling rate (energy splitting), site correlations, fluctuations of the number of quanta, and entanglement. We observe how these properties are reflected in the time evolution of initially localized excitations. Quantum breathers manifest as pairs of nearly degenerate eigenstates that show strong site correlation of quanta, and are characterized by a strong excitation of quanta on one site of the network which perform slow coherent tunneling motion from one site to another. They enhance the fluctuations of quanta, and are the least entangled states among the group of eigenstates in the same range of the energy spectrum. We use our analysis methods to consider the excitation of quantum breathers in a cell of two coupled Josephson junctions, and study their properties as compared with those in the previous cases. We describe how quantum breathers could be experimentally observed by employing the already developed techniques for quantum information processing with Josephson junctions. (orig.)

  11. The ultrastructure of the muscle coat of human gastro-oesophageal junction, with special reference to interstitial cells of Cajal

    Directory of Open Access Journals (Sweden)

    Faussone-Pellegrini eMaria-Simonetta

    2013-04-01

    Full Text Available The muscle coat of the human lower oesophageal sphincter and stomach was studied 5 cm above and 4 cm below the gastro-oesophageal junction. Four subjects were operated on for motility disorders of the oesophagus, two for a hypertensive lower oesophageal sphincter and two for an epiphrenic diverticulum; six subjects were operated on for oesophageal or gastric carcinomas. Specimens were fixed in phosphate-buffered OsO4, embedded in Epon, contrasted with uranyl acetate and lead citrate and observed under a Siemens Elmiskop Ia electron microscope. Both the oesophageal and gastric muscle cells, which showed features typical of this cell type, were innervated by multiple varicosities that were rich in synaptic vesicles; these varicosities were generally rarely encountered at distances less than 1000 Å from muscle cells. Only a very few, close neuromuscular junctions were detected. Special cells, which correspond to the interstitial cells of Cajal as reported by other authors, were discerned at the periphery of muscle cell bundles. These cells were characterized by an elongated cell body with many thin branches and an oval, sometimes indented nucleus. Some pinocytotic vesicles were located at the cell periphery. These cells were surrounded by a discontinuous basal lamina and were seen in close contact with each other and with muscle cells; the close contact areas were often very wide. The cytoplasm contained variable amounts of mitochondria, a well-developed smooth endoplasmic reticulum and a Golgi complex. As a characteristic feature, bundles of thin filaments were located at the cell periphery and were attached to electron-dense areas of the cell membrane. Morphologically, these filaments resembled myofilaments; they were present in variable amounts and were sometimes very numerous. The observation that the cytoplasmic organelles and filaments varied in number, is probably related to the different functional properties of these cells

  12. Reprogramming of cell junction modules during stepwise epithelial to mesenchymal transition and accumulation of malignant features in vitro in a prostate cell model

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Xi-song, E-mail: Xisong.Ke@gades.uib.no [The Gade Institute, University of Bergen, Bergen (Norway); Department of Microbiology, Haukeland, University Hospital, Bergen (Norway); Li, Wen-cheng [The Gade Institute, University of Bergen, Bergen (Norway); Urological Department, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Hovland, Randi [Center of Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen (Norway); Department of Molecular Biology, University of Bergen, Bergen (Norway); Qu, Yi [The Gade Institute, University of Bergen, Bergen (Norway); Liu, Run-hui [Modern Research Center for Traditional Chinese Medicine, Second Military Medical University, Shanghai (China); McCormack, Emmet [Department of Medicine, Haukeland University Hospital, Bergen (Norway); Thorsen, Frits [Department of Biomedicine, University of Bergen, Bergen (Norway); Olsen, Jan Roger [The Gade Institute, University of Bergen, Bergen (Norway); Molven, Anders [The Gade Institute, University of Bergen, Bergen (Norway); Department of Pathology, Haukeland University Hospital, Bergen (Norway); Kogan-Sakin, Ira; Rotter, Varda [Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot (Israel); Akslen, Lars A. [The Gade Institute, University of Bergen, Bergen (Norway); Department of Pathology, Haukeland University Hospital, Bergen (Norway); Oyan, Anne Margrete [The Gade Institute, University of Bergen, Bergen (Norway); Department of Microbiology, Haukeland, University Hospital, Bergen (Norway); Kalland, Karl-Henning, E-mail: Kalland@gades.uib.no [The Gade Institute, University of Bergen, Bergen (Norway); Department of Microbiology, Haukeland, University Hospital, Bergen (Norway)

    2011-01-15

    Epithelial to mesenchymal transition (EMT) is pivotal in tumor metastasis. Our previous work reported an EMT model based on primary prostate epithelial cells (EP156T) which gave rise to cells with mesenchymal phenotype (EPT1) without malignant transformation. To promote prostate cell transformation, cells were maintained in saturation density cultures to select for cells overriding quiescence. Foci formed repeatedly following around 8 weeks in confluent EPT1 monolayers. Only later passage EPT1, but not EP156T cells of any passage, could form foci. Cells isolated from the foci were named EPT2 and formed robust colonies in soft agar, a malignant feature present neither in EP156T nor in EPT1 cells. EPT2 cells showed additional malignant traits in vitro, including higher ability to proliferate following confluence, higher resistance to apoptosis and lower dependence on exogenous growth factors than EP156T and EPT1 cells. Microarray profiling identified gene sets, many of which belong to cell junction modules, that changed expression from EP156T to EPT1 cells and continued to change from EPT1 to EPT2 cells. Our findings provide a novel stepwise cell culture model in which EMT emerges independently of transformation and is associated with subsequent accumulation of malignant features in prostate cells. Reprogramming of cell junction modules is involved in both steps.

  13. Reprogramming of cell junction modules during stepwise epithelial to mesenchymal transition and accumulation of malignant features in vitro in a prostate cell model

    International Nuclear Information System (INIS)

    Epithelial to mesenchymal transition (EMT) is pivotal in tumor metastasis. Our previous work reported an EMT model based on primary prostate epithelial cells (EP156T) which gave rise to cells with mesenchymal phenotype (EPT1) without malignant transformation. To promote prostate cell transformation, cells were maintained in saturation density cultures to select for cells overriding quiescence. Foci formed repeatedly following around 8 weeks in confluent EPT1 monolayers. Only later passage EPT1, but not EP156T cells of any passage, could form foci. Cells isolated from the foci were named EPT2 and formed robust colonies in soft agar, a malignant feature present neither in EP156T nor in EPT1 cells. EPT2 cells showed additional malignant traits in vitro, including higher ability to proliferate following confluence, higher resistance to apoptosis and lower dependence on exogenous growth factors than EP156T and EPT1 cells. Microarray profiling identified gene sets, many of which belong to cell junction modules, that changed expression from EP156T to EPT1 cells and continued to change from EPT1 to EPT2 cells. Our findings provide a novel stepwise cell culture model in which EMT emerges independently of transformation and is associated with subsequent accumulation of malignant features in prostate cells. Reprogramming of cell junction modules is involved in both steps.

  14. Reprogramming of cell junction modules during stepwise epithelial to mesenchymal transition and accumulation of malignant features in vitro in a prostate cell model.

    Science.gov (United States)

    Ke, Xi-song; Li, Wen-cheng; Hovland, Randi; Qu, Yi; Liu, Run-hui; McCormack, Emmet; Thorsen, Frits; Olsen, Jan Roger; Molven, Anders; Kogan-Sakin, Ira; Rotter, Varda; Akslen, Lars A; Oyan, Anne Margrete; Kalland, Karl-Henning

    2011-01-15

    Epithelial to mesenchymal transition (EMT) is pivotal in tumor metastasis. Our previous work reported an EMT model based on primary prostate epithelial cells (EP156T) which gave rise to cells with mesenchymal phenotype (EPT1) without malignant transformation. To promote prostate cell transformation, cells were maintained in saturation density cultures to select for cells overriding quiescence. Foci formed repeatedly following around 8 weeks in confluent EPT1 monolayers. Only later passage EPT1, but not EP156T cells of any passage, could form foci. Cells isolated from the foci were named EPT2 and formed robust colonies in soft agar, a malignant feature present neither in EP156T nor in EPT1 cells. EPT2 cells showed additional malignant traits in vitro, including higher ability to proliferate following confluence, higher resistance to apoptosis and lower dependence on exogenous growth factors than EP156T and EPT1 cells. Microarray profiling identified gene sets, many of which belong to cell junction modules, that changed expression from EP156T to EPT1 cells and continued to change from EPT1 to EPT2 cells. Our findings provide a novel stepwise cell culture model in which EMT emerges independently of transformation and is associated with subsequent accumulation of malignant features in prostate cells. Reprogramming of cell junction modules is involved in both steps. PMID:20969863

  15. Long-range superharmonic Josephson current and spin-triplet pairing correlations in a junction with ferromagnetic bilayers.

    Science.gov (United States)

    Meng, Hao; Wu, Jiansheng; Wu, Xiuqiang; Ren, Mengyuan; Ren, Yajie

    2016-01-01

    The long-range spin-triplet supercurrent transport is an interesting phenomenon in the superconductor/ferromagnet () heterostructure containing noncollinear magnetic domains. Here we study the long-range superharmonic Josephson current in asymmetric junctions. It is demonstrated that this current is induced by spin-triplet pairs  -  or  +  in the thick layer. The magnetic rotation of the particularly thin layer will not only modulate the amplitude of the superharmonic current but also realise the conversion between  -  and  + . Moreover, the critical current shows an oscillatory dependence on thickness and exchange field in the layer. These effect can be used for engineering cryoelectronic devices manipulating the superharmonic current. In contrast, the critical current declines monotonically with increasing exchange field of the layer, and if the layer is converted into half-metal, the long-range supercurrent is prohibited but still exists within the entire region. This phenomenon contradicts the conventional wisdom and indicates the occurrence of spin and charge separation in present junction, which could lead to useful spintronics devices. PMID:26892755

  16. Microcrystalline single and double junction silicon based solar cells entirely prepared by HWCVD on textured zinc oxide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P.; Kupich, M.; Schroeder, B. [Department of Physics, Center of Optical Technologies and Laser Controlled Processes, University of Kaiserslautern, P.O. Box 3049, Kaiserslautern, D-67653 (Germany); Bock, W. [Institute for Oberflachen Schicht Analytic, Kaiserslautern (Germany); Dusane, R.O. [Department of Metallurgical Engineering and Material Science, Indian Institute of Technology, Bombay (India)

    2006-06-15

    Microcrystalline silicon based single junction pin and amorphous-microcrystalline double junction pinpin solar cells were fabricated entirely by hot-wire chemical vapor deposition on textured zinc oxide substrates. The short circuit current density for microcrystalline pin cells shows an increase of 20-25% compared to unetched zinc oxide, indicating a better light trapping on textured zinc oxide substrate. The best initial conversion efficiency obtained for an all hot-wire microcrystalline p-i-n solar cell was 7.6%. Micromorph a-Si:H/{mu}c-Si:H pinpin tandem solar cells were also investigated entirely by hot-wire CVD showing best initial conversion efficiency {eta}=8.25%. The microcrystalline pin cells show an increase of series resistance even in the dark resulting in decrease of fill factor, however micromorph pinpin cells are stable in the dark. This instability of {mu}c-Si:H pin cells could be mainly attributed to inter-diffusion at the TCO-p interfacial region. (author)

  17. Blocking junctional adhesion molecule C enhances dendritic cell migration and boosts the immune responses against Leishmania major.

    Directory of Open Access Journals (Sweden)

    Romain Ballet

    2014-12-01

    Full Text Available The recruitment of dendritic cells to sites of infections and their migration to lymph nodes is fundamental for antigen processing and presentation to T cells. In the present study, we showed that antibody blockade of junctional adhesion molecule C (JAM-C on endothelial cells removed JAM-C away from junctions and increased vascular permeability after L. major infection. This has multiple consequences on the output of the immune response. In resistant C57BL/6 and susceptible BALB/c mice, we found higher numbers of innate immune cells migrating from blood to the site of infection. The subsequent migration of dendritic cells (DCs from the skin to the draining lymph node was also improved, thereby boosting the induction of the adaptive immune response. In C57BL/6 mice, JAM-C blockade after L. major injection led to an enhanced IFN-γ dominated T helper 1 (Th1 response with reduced skin lesions and parasite burden. Conversely, anti JAM-C treatment increased the IL-4-driven T helper 2 (Th2 response in BALB/c mice with disease exacerbation. Overall, our results show that JAM-C blockade can finely-tune the innate cell migration and accelerate the consequent immune response to L. major without changing the type of the T helper cell response.

  18. Epidermis–dermis junction as a novel location for bone marrow-derived cells to reside in response to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Junko, E-mail: jokano@belle.shiga-med.ac.jp [Division of Anatomy and Cell Biology, Shiga University of Medical Science, Shiga (Japan); Kojima, Hideto; Katagi, Miwako [Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Shiga (Japan); Nakae, Yuki [Department of Internal Medicine, Shiga University of Medical Science, Shiga (Japan); Terashima, Tomoya [Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Shiga (Japan); Nakagawa, Takahiko [TMK Project, Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto (Japan); Kurakane, Takeshi; Okamoto, Naoki; Morohashi, Keita [Division of Anatomy and Cell Biology, Shiga University of Medical Science, Shiga (Japan); Maegawa, Hiroshi [Department of Internal Medicine, Shiga University of Medical Science, Shiga (Japan); Udagawa, Jun [Division of Anatomy and Cell Biology, Shiga University of Medical Science, Shiga (Japan)

    2015-06-12

    Bone marrow-derived cells (BMDCs) can migrate into the various organs in the mice irradiated by ionizing radiation (IR). However, it may not be the case in the skin. While IR is used for bone marrow (BM) transplantation, studying with the epidermal sheets demonstrated that the BMDC recruitment is extraordinarily rare in epidermis in the mouse. Herein, using the chimera mice with BM from green fluorescent protein (GFP) transgenic mice, we simply examined if BMDCs migrate into any layers in the total skin, as opposed to the epidermal sheets, in response to IR. Interestingly, we identified the presence of GFP-positive (GFP{sup +}) cells in the epidermis-dermis junction in the total skin sections although the epidermal cell sheets failed to have any GFP cells. To examine a possibility that the cells in the junction could be mechanically dissociated during separating epidermal sheets, we then salvaged such dissociated cells and examined its characteristics. Surprisingly, some GFP{sup +} cells were found in the salvaged cells, indicating that these cells could be derived from BM. In addition, such BMDCs were also associated with inflammation in the junction. In conclusion, BMDCs can migrate to and reside in the epidermis-dermis junction after IR. - Highlights: • Bone marrow-derived cells (BMDCs) migrate in the epidermis due to ionizing radiation (IR). • BMDCs dissociate from the epidermis-dermis junction in preparing epidermal sheets. • The doses of IR determine the location and the number of migrating BMDCs in the skin.

  19. Epidermis–dermis junction as a novel location for bone marrow-derived cells to reside in response to ionizing radiation

    International Nuclear Information System (INIS)

    Bone marrow-derived cells (BMDCs) can migrate into the various organs in the mice irradiated by ionizing radiation (IR). However, it may not be the case in the skin. While IR is used for bone marrow (BM) transplantation, studying with the epidermal sheets demonstrated that the BMDC recruitment is extraordinarily rare in epidermis in the mouse. Herein, using the chimera mice with BM from green fluorescent protein (GFP) transgenic mice, we simply examined if BMDCs migrate into any layers in the total skin, as opposed to the epidermal sheets, in response to IR. Interestingly, we identified the presence of GFP-positive (GFP+) cells in the epidermis-dermis junction in the total skin sections although the epidermal cell sheets failed to have any GFP cells. To examine a possibility that the cells in the junction could be mechanically dissociated during separating epidermal sheets, we then salvaged such dissociated cells and examined its characteristics. Surprisingly, some GFP+ cells were found in the salvaged cells, indicating that these cells could be derived from BM. In addition, such BMDCs were also associated with inflammation in the junction. In conclusion, BMDCs can migrate to and reside in the epidermis-dermis junction after IR. - Highlights: • Bone marrow-derived cells (BMDCs) migrate in the epidermis due to ionizing radiation (IR). • BMDCs dissociate from the epidermis-dermis junction in preparing epidermal sheets. • The doses of IR determine the location and the number of migrating BMDCs in the skin

  20. Cell-mapping description of coexisting phase-locked soliton states in a long ac-biased Josephson junction

    International Nuclear Information System (INIS)

    The coexistence of phase-locked soliton states in a long ac-biased Josephson junction is pointed out on the basis of numerical calculations. We use a combined interpolation and cell-mapping technique to calculate periodic orbits along with their stability and basins of attraction. The dominant coexistent phase-locked states consist of the well-known zero-field step (shuttling regime of solitons) and the so-called C-cycle dynamics. In the latter the soliton is bouncing only at one end of the junction, therefore producing no average voltage. The probability of reaching the basins of attraction of these different motions explains the hysteresis and the complicated fine structure in the current-voltage curve obtained from the model equation

  1. Diurnal variation of tight junction integrity associates inversely with matrix metalloproteinase expression in Xenopus laevis corneal epithelium: implications for circadian regulation of homeostatic surface cell desquamation.

    Directory of Open Access Journals (Sweden)

    Allan F Wiechmann

    Full Text Available The corneal epithelium provides a protective barrier against pathogen entrance and abrasive forces, largely due to the intercellular junctional complexes between neighboring cells. After a prescribed duration at the corneal surface, tight junctions between squamous surface cells must be disrupted to enable them to desquamate as a component of the tissue homeostatic renewal. We hypothesize that matrix metalloproteinase (MMPs are secreted by corneal epithelial cells and cleave intercellular junctional proteins extracellularly at the epithelial surface. The purpose of this study was to examine the expression of specific MMPs and tight junction proteins during both the light and dark phases of the circadian cycle, and to assess their temporal and spatial relationships in the Xenopus laevis corneal epithelium.Expression of MMP-2, tissue inhibitor of MMP-2 (TIMP-2, membrane type 1-MMP (MT1-MMP and the tight junction proteins occludin and claudin-4 were examined by confocal double-label immunohistochemistry on corneas obtained from Xenopus frogs at different circadian times. Occludin and claudin-4 expression was generally uniformly intact on the surface corneal epithelial cell lateral membranes during the daytime, but was frequently disrupted in small clusters of cells at night. Concomitantly, MMP-2 expression was often elevated in a mosaic pattern at nighttime and associated with clusters of desquamating surface cells. The MMP-2 binding partners, TIMP-2 and MT1-MMP were also localized to surface corneal epithelial cells during both the light and dark phases, with TIMP-2 tending to be elevated during the daytime.MMP-2 protein expression is elevated in a mosaic pattern in surface corneal epithelial cells during the nighttime in Xenopus laevis, and may play a role in homeostatic surface cell desquamation by disrupting intercellular junctional proteins. The sequence of MMP secretion and activation, tight junction protein cleavage, and subsequent surface

  2. Simulation of In{sub 0.65}Ga{sub 0.35} N single-junction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaobin [Novel Semiconductor Material Lab, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); Wang Xiaoliang; Xiao Hongling; Yang Cuibai; Ran Junxue; Wang Cuimei; Hou Qifeng; Li Jinmin

    2007-12-07

    The performances of In{sub 0.65}Ga{sub 0.35}N single-junction solar cells with different structures, including various doping densities and thicknesses of each layer, have been simulated. It is found that the optimum efficiency of a In{sub 0.65}Ga{sub 0.35}N solar cell is 20.284% with 5 x 10{sup 17} cm{sup -3} carrier concentration of the front and basic regions, a 130 nm thick p-layer and a 270 nm thick n-layer.

  3. Origin of correlated activity between parasol retinal ganglion cells

    OpenAIRE

    Khuc-Trong, Philipp; Rieke, Fred

    2008-01-01

    Cells throughout the central nervous system exhibit synchronous activity patterns - i.e. a cell’s probability of generating an action potential depends both on its firing rate and on the occurrence of action potentials in surrounding cells. The mechanisms producing synchronous or correlated activity are poorly understood despite its prevalence and potential impact on neural coding. We find that neighboring parasol retinal ganglion cells receive strongly correlated synaptic input in the absenc...

  4. Peripheral selection of V delta 1+ cells with restricted T cell receptor delta gene junctional repertoire in the peripheral blood of healthy donors

    OpenAIRE

    1993-01-01

    To characterize the T cell receptor (TCR) repertoire expressed by the V delta 1+ gamma/delta T cell population, we have studied the V delta 1-J delta 1 junctional sequences from peripheral blood samples of healthy donors. We show that, surprisingly, this repertoire is restricted in most healthy adults, with a donor-specific and relatively stable pattern, whereas this repertoire remains unrestricted in infants, and is similar to that of thymocytes. These data contrast with the general assumpti...

  5. High-Throughput Flow Cytometry Screening Reveals a Role for Junctional Adhesion Molecule A as a Cancer Stem Cell Maintenance Factor

    Directory of Open Access Journals (Sweden)

    Justin D. Lathia

    2014-01-01

    Full Text Available Stem cells reside in niches that regulate the balance between self-renewal and differentiation. The identity of a stem cell is linked with the ability to interact with its niche through adhesion mechanisms. To identify targets that disrupt cancer stem cell (CSC adhesion, we performed a flow cytometry screen on patient-derived glioblastoma (GBM cells and identified junctional adhesion molecule A (JAM-A as a CSC adhesion mechanism essential for self-renewal and tumor growth. JAM-A was dispensable for normal neural stem/progenitor cell (NPC function, and JAM-A expression was reduced in normal brain versus GBM. Targeting JAM-A compromised the self-renewal of CSCs. JAM-A expression negatively correlated to GBM patient prognosis. Our results demonstrate that GBM-targeting strategies can be identified through screening adhesion receptors and JAM-A represents a mechanism for niche-driven CSC maintenance.

  6. Simulation and optimization of current and lattice matching double-junction GaNAsP/Si solar cells

    Science.gov (United States)

    Nacer, S.; Aissat, A.

    2016-01-01

    This paper deals with theoretical investigation of the performance of current and lattice matched GaNxAsyP1-x-y/Si double-junction solar cells. The nitrogen and arsenic concentrations ensuring lattice matching to Si are determined. The band gap of GaNAsP is calculated using the band anti-crossing model. Calculations were performed under 1-sun AM1.5 using the one diode ideal model. Impact of minor carrier lifetime and surface recombination in the top sub-cell on the cell performances is analyzed. Optimum compositions of the top sub-cell have been identified (x = 4.5%, y = 11.5% and Eg = 1.68 eV). The simulation results predict, for the optimized GaNAsP/Si double-junction solar cell, a short circuit current Jsc = 20 mA/cm2, an open circuit voltage Voc = 1.95 V, and a conversion efficiency η = 37.5%.

  7. Numerical Validation of a New Approach to Model Single Junction Low Concentration PV Cells under Non-Uniform Illumination

    Directory of Open Access Journals (Sweden)

    Hang Zhou

    2015-05-01

    Full Text Available This study presents a numerical validation of a new approach to model single junction PV cell under non-uniform illumination for low-concentration solar collectors such as compound parabolic concentrators (CPC. The simulation is achieved by finite element modelling (FEM. To characterize the results, the model is simulated with five different non-uniform illumination profiles. The results indicate that increasing the non-uniformity of concentrated light will introduce more resistive losses and lead to a significant attenuation in the PV cell short-circuit current. The FEM modelling results are then used to validate the array modelling approach, in which a single junction PV cell is considered equivalent to a parallel-connected array of several cell splits. A comparison between the FEM and array modelling approaches shows good agreement. Therefore, the array modelling approach is a fast way to investigate the PV cell performance under non-uniform illumination, while the FEM approach is useful in optimizing design of fingers and bus-bars on a PV.

  8. Composite Transparent Electrode of Graphene Nanowalls and Silver Nanowires on Micropyramidal Si for High-Efficiency Schottky Junction Solar Cells.

    Science.gov (United States)

    Jiao, Tianpeng; Liu, Jian; Wei, Dapeng; Feng, Yanhui; Song, Xuefen; Shi, Haofei; Jia, Shuming; Sun, Wentao; Du, Chunlei

    2015-09-16

    The conventional graphene-silicon Schottky junction solar cell inevitably involves the graphene growth and transfer process, which results in complicated technology, loss of quality of the graphene, extra cost, and environmental unfriendliness. Moreover, the conventional transfer method is not well suited to conformationally coat graphene on a three-dimensional (3D) silicon surface. Thus, worse interfacial conditions are inevitable. In this work, we directly grow graphene nanowalls (GNWs) onto the micropyramidal silicon (MP) by the plasma-enhanced chemical vapor deposition method. By controlling growth time, the cell exhibits optimal pristine photovoltaic performance of 3.8%. Furthermore, we improve the conductivity of the GNW electrode by introducing the silver nanowire (AgNW) network, which could achieve lower sheet resistance. An efficiency of 6.6% has been obtained for the AgNWs-GNWs-MP solar cell without any chemical doping. Meanwhile, the cell exhibits excellent stability exposed to air. Our studies show a promising way to develop simple-technology, low-cost, high-efficiency, and stable Schottky junction solar cells. PMID:26308388

  9. Qigesan inhibits migration and invasion of esophageal cancer cells via inducing connexin expression and enhancing gap junction function.

    Science.gov (United States)

    Shi, Huijuan; Shi, Dongxuan; Wu, Yansong; Shen, Qiang; Li, Jing

    2016-09-28

    Qigesan (QGS), a well-known traditional Chinese medicinal formula, has long been used to treat patients with esophageal cancer. However, the anticancer mechanisms of action of QGS remain unknown. This study aims to determine whether QGS regulates gap junction (GJ) function and affects the invasiveness of esophageal cancer cells. Our results demonstrate that QGS markedly inhibits the migration and invasion of esophageal cancer cells in vitro. We further show that QGS enhances the function of GJ in esophageal cancer cells. We therefore hypothesized that enhanced connexin expression leads to enhanced GJ function and inhibition of metastasis. We found that QGS enhances expression of connexin 26 and connexin 43 in esophageal cancer cells. This study suggests that QGS increases GJ function via enhancing the expression of connexins, resulting in reduced esophageal cancer cell migration and invasion. PMID:27345741

  10. Freeze-fracture study of the epidermal cells of a teleost with particular reference to intercellular junctions and permeability to tracer.

    Science.gov (United States)

    Ferri, S; Sesso, A

    1979-01-01

    The plasmatic membranes, the intercellular junctions and the intercellular spaces of the epidermis of the fish Pimelodus maculatus were studied by freeze-fracture and by lanthanum methods. The observations has confirmed the presence of desmosomes. Gap junctions were not found and the tight junctions can be seen very rarely, arranged to form small discrete maculae. The finger-print pattern due to the microridges of the apical plasma membrane of the superficial cells was studied by direct replicas. The tracer penetrates all the intercellular epidermal spaces but failed to penetrate the dermis, suggesting the presence of a barrier at the dermo-epidermal level. PMID:574691

  11. Low temperature fabrication of high performance p-n junction on the Ti foil for use in large-area flexible dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: • A new p-n junction is prepared and used in the large-area flexible DSSC as an anode. • The p-n junction formes a directional pathway for the charge separation and electron transport. • The p-n junction showes low charge-transfer resistance and high effective electron lifetime. • The efficiency of the large-area flexible DSSC reaches 6.51% based on the p-n junction. - Abstract: A p-n junction of poly (3,4-ethylenedioxythiophene) (PEDOT) - dye-sensitized TiO2 is introduced into the large-area flexible dye-sensitized solar cell (DSSC) as an anode. This p-n junction is fabricated using a cyclic voltammetry electropolymerization of PEDOT onto a Ti foil substrate, and then treated in the aqueous ammonia, finally subjected to coating TiO2 by a doctor-scraping technique, all of preparations and treatments are carried out under low temperature. The obtained p-n junction forms a single directional pathway for electron transport which benefites the charge separation. The large-area (10 cm2) flexible DSSC with the p-n junction demonstrates an enhanced photovoltaic conversion efficiency of up to 6.51% compared to 4.89% for the DSSC without the p-n junction due to its low series resistance and charge-transfer resistance, high effective electron lifetime for recombination. As a result, the DSSC fabricated using the p-n junction can be suitable for high powered DSSC applications

  12. Structural correlates of rotavirus cell entry.

    Directory of Open Access Journals (Sweden)

    Aliaa H Abdelhakim

    2014-09-01

    Full Text Available Cell entry by non-enveloped viruses requires translocation into the cytosol of a macromolecular complex--for double-strand RNA viruses, a complete subviral particle. We have used live-cell fluorescence imaging to follow rotavirus entry and penetration into the cytosol of its ∼ 700 Å inner capsid particle ("double-layered particle", DLP. We label with distinct fluorescent tags the DLP and each of the two outer-layer proteins and track the fates of each species as the particles bind and enter BSC-1 cells. Virions attach to their glycolipid receptors in the host cell membrane and rapidly become inaccessible to externally added agents; most particles that release their DLP into the cytosol have done so by ∼ 10 minutes, as detected by rapid diffusional motion of the DLP away from residual outer-layer proteins. Electron microscopy shows images of particles at various stages of engulfment into tightly fitting membrane invaginations, consistent with the interpretation that rotavirus particles drive their own uptake. Electron cryotomography of membrane-bound virions also shows closely wrapped membrane. Combined with high resolution structural information about the viral components, these observations suggest a molecular model for membrane disruption and DLP penetration.

  13. InGaAsP/InGaAs tandem photovoltaic devices for four-junction solar cells

    International Nuclear Information System (INIS)

    Lattice-matched InGaAs(P) photovoltaic devices were grown on InP substrates by metal-organic chemical vapor deposition. InGaAsP/InGaAs (1.07/0.74 eV) dual-junction (DJ) solar cells were fabricated and characterized by quantum efficiency and I–V measurements. The open circuit voltage, short circuit current density, fill factor, and efficiency of InGaAsP/InGaAs DJ solar cell are 0.977 V, 10.2 mA/cm2, 80.8%, and 8.94%, respectively, under one sun illumination of the AM 1.5D spectrum. For the InGaAsP/InGaAs DJ solar cell, with increasing concentration, the conversion efficiency first increases steadily and reaches 13% around 280 suns, and finally decreases due to the drop in fill factor at higher concentration ratios. These experimental results demonstrate the promising prospect of GaInP/GaAs/InGaAsP/InGaAs four-junction solar cells. (paper)

  14. Long-Term Stability and Safety of Transgenic Cultured Epidermal Stem Cells in Gene Therapy of Junctional Epidermolysis Bullosa

    Directory of Open Access Journals (Sweden)

    Laura De Rosa

    2014-01-01

    Full Text Available We report a long-term follow-up (6.5 years of a phase I/II clinical trial envisaging the use of autologous genetically modified cultured epidermal stem cells for gene therapy of junctional epidermolysis bullosa, a devastating genetic skin disease. The critical goals of the trial were to evaluate the safety and long-term persistence of genetically modified epidermis. A normal epidermal-dermal junction was restored and the regenerated transgenic epidermis was found to be fully functional and virtually indistinguishable from a normal control. The epidermis was sustained by a discrete number of long-lasting, self-renewing transgenic epidermal stem cells that maintained the memory of the donor site, whereas the vast majority of transduced transit-amplifying progenitors were lost within the first few months after grafting. These data pave the way for the safe use of epidermal stem cells in combined cell and gene therapy for genetic skin diseases.

  15. Quadruple-junction thin-film silicon-based solar cells with high open-circuit voltage

    Science.gov (United States)

    Si, Fai Tong; Kim, Do Yun; Santbergen, Rudi; Tan, Hairen; van Swaaij, René A. C. M. M.; Smets, Arno H. M.; Isabella, Olindo; Zeman, Miro

    2014-08-01

    We have fabricated a-SiOx:H/a-Si:H/nc-Si:H/nc-Si:H quadruple-junction thin-film silicon-based solar cells (4J TFSSCs) to obtain high spectral utilization and high voltages. By processing the solar cells on micro-textured superstrates, extremely high open-circuit voltages for photovoltaic technology based on thin-film silicon alloys up to 2.91 V have been achieved. Optical simulations of quadruple-junction solar cells using an advanced in-house model are a crucial tool to effectively tackle the challenging task of current matching among the individual sub-cells in such devices. After optimizing the optical design of the device and the absorber thicknesses, an energy conversion efficiency of 11.4% has been achieved. The open-circuit voltage, short-circuit current density, and fill factor were 2.82 V, 5.49 mA/cm2, and 73.9%, respectively. Based on this demonstration, strategies for further development of highly efficient 4J TFSSCs are proposed.

  16. Cholera toxin disrupts barrier function by inhibiting exocyst-mediated trafficking of host proteins to intestinal cell junctions

    Science.gov (United States)

    Guichard, Annabel; Moreno, Beatriz Cruz; Aguilar, Berenice; van Sorge, Nina M.; Kuang, Jennifer; Kurkciyan, Adrianne A.; Wang, Zhipeng; Hang, Saiyu; Pineton de Chambrun, Guillaume P.; McCole, Declan F.; Watnick, Paula; Nizet, Victor; Bier, Ethan

    2013-01-01

    Summary Cholera toxin (CT), a virulence factor elaborated by Vibrio cholerae, is sufficient to induce the severe diarrhea characteristic of cholera. The enzymatic moiety of CT (CtxA) increases cAMP synthesis in intestinal epithelial cells, leading to chloride ion (Cl−) efflux through the CFTR Cl− channel. To preserve electroneutrality and osmotic balance, sodium ions and water also flow into the intestinal lumen via a paracellular route. We find that CtxA-driven cAMP increase also inhibits Rab11/exocyst-mediated trafficking of host proteins including E-cadherin and Notch signaling components to cell-cell junctions in Drosophila, human intestinal epithelial cells, and ligated mouse ileal loops, thereby disrupting barrier function. Additionally, CtxA induces junctional damage, weight loss, and dye leakage in the Drosophila gut, contributing to lethality from live V. cholerae infection, all of which can be rescued by Rab11 over-expression. These barrier-disrupting effects of CtxA may act in parallel with Cl− secretion to drive the pathophysiology of cholera. PMID:24034615

  17. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells

    Science.gov (United States)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, Junho; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-06-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the

  18. In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions

    Science.gov (United States)

    Harris, R.D.; Imaizumi, M.; Walters, R.J.; Lorentzen, J.R.; Messenger, S.R.; Tischler, J.G.; Ohshima, T.; Sato, S.; Sharps, P.R.; Fatemi, N.S.

    2008-01-01

    The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

  19. Atom-scale compositional distribution in InAlAsSb-based triple junction solar cells by atom probe tomography.

    Science.gov (United States)

    Hernández-Saz, J; Herrera, M; Delgado, F J; Duguay, S; Philippe, T; Gonzalez, M; Abell, J; Walters, R J; Molina, S I

    2016-07-29

    The analysis by atom probe tomography (APT) of InAlAsSb layers with applications in triple junction solar cells (TJSCs) has shown the existence of In- and Sb-rich regions in the material. The composition variation found is not evident from the direct observation of the 3D atomic distribution and because of this a statistical analysis has been required. From previous analysis of these samples, it is shown that the small compositional fluctuations determined have a strong effect on the optical properties of the material and ultimately on the performance of TJSCs. PMID:27306098

  20. Non-destructive technique to measurement and separation of I-V curves of monolithic multi-junction solar cells

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; Vaněček, Milan

    Munich: WIP- Renewable Energies, 2009 - (Sinke, W.; Ossenbrink, H.; Helm, P.), s. 2757-2759 ISBN 3-936338-25-6. [European Photovoltaic Solar Energy Conference /24./. Hamburg (DE), 21.09.2009-25.09.2009] R&D Projects: GA ČR GD202/09/H041; GA ČR GA202/09/0417 Grant ostatní: European Commission(XE) 038885 (SES6) Institutional research plan: CEZ:AV0Z10100521 Keywords : solar cells * multi-junction * tandem * I-V Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. Carrier generation, recombination, trapping, and transport in semiconductors with position-dependent composition. [in junction solar cells

    Science.gov (United States)

    Sah, C.-T.; Lindholm, F. A.

    1977-01-01

    The spatial variation of the chemical composition of a semiconductor modifies the ideal one-electron energy band model as well as the Shockley equations for carrier recombination and transport in two important ways. The random component of the spatial variation introduces localized states in the energy gap by perturbing the band states. The nonrandom component gives rise to the position dependences of the conduction and valence band edges or the electron affinity and the energy gap. This paper gives the modifications of the Shockley equations from these two effects as well as an example of the steady-state recombination rate from distributed gap states in junction solar cells

  2. Three-Year Performance Evaluation of Single Junction Amorphous Solar Cells Grid-Connected Power Station in Libya

    OpenAIRE

    2013-01-01

    Photovoltaic (PV) conservation of solar energy is one of the most promising sources of future energy. Grid-connected PV systems are widely used in many countries, but in Libya it is just started. A PV grid-connected of 24 KWP PV system has been installed as a pilot project to deliver AC energy to the Tripoli University electric grid; the system is of single junction amorphous solar cells which were erected in Sep. 2009; it consists of 240 Mitsubishi thin film amorphous PV Modules of MA100T2 t...

  3. Atom-scale compositional distribution in InAlAsSb-based triple junction solar cells by atom probe tomography

    Science.gov (United States)

    Hernández-Saz, J.; Herrera, M.; Delgado, F. J.; Duguay, S.; Philippe, T.; Gonzalez, M.; Abell, J.; Walters, R. J.; Molina, S. I.

    2016-07-01

    The analysis by atom probe tomography (APT) of InAlAsSb layers with applications in triple junction solar cells (TJSCs) has shown the existence of In- and Sb-rich regions in the material. The composition variation found is not evident from the direct observation of the 3D atomic distribution and because of this a statistical analysis has been required. From previous analysis of these samples, it is shown that the small compositional fluctuations determined have a strong effect on the optical properties of the material and ultimately on the performance of TJSCs.

  4. The oligodendroglial precursor cell line Oli-neu represents a cell culture system to examine functional expression of the mouse gap junction gene connexin29 (Cx29

    Directory of Open Access Journals (Sweden)

    SonjaHombach

    2013-06-01

    Full Text Available The potential gap junction forming mouse connexin29 (Cx29 protein is concomitantly expressed with connexin32 (Cx32 in peripheral myelin forming Schwann cells and together with both Cx32 and connexin47 (Cx47 in oligodendrocytes of the CNS. To study the genomic structure and functional expression of Cx29, either primary cells or cell culture systems might be selected, from which the latter are easier to cultivate. Both structure and expression of Cx29 is still not fully understood. In the mouse sciatic nerve, brain and the oligodendroglial precursor cell line Oli-neu the Cx29 gene is processed in two transcript isoforms both harbouring a unique reading frame. In contrast to Cx32 and Cx47, only Cx29 protein is abundantly expressed in undifferentiated as well as differentiated Oli-neu cells but the absence of Etbr dye transfer after microinjection concealed the function of Cx29 mediated gap junction communication between those cells. Although HeLa cells stably transfected with Cx29 or Cx29-eGFP neither demonstrated any permeability for Lucifer yellow nor for neurobiotin, blocking of Etbr uptake from the media by gap junction blockers does suppose a role of Cx29 in hemi-channel function. Thus, we conclude that, due to its high abundance of Cx29 expression and its reproducible culture conditions, the oligodendroglial precursor cell line Oli-neu might constitute an appropriate cell culture system to study molecular mechanisms or putative extracellular stimuli to functionally open Cx29 channels or hemi-channels.

  5. Understanding causes and effects of non-uniform light distributions on multi-junction solar cells: Procedures for estimating efficiency losses

    Science.gov (United States)

    Herrero, Rebeca; Victoria, Marta; Domínguez, César; Askins, Stephen; Antón, Ignacio; Sala, Gabriel

    2015-09-01

    This paper presents the mechanisms of efficiency losses that have to do with the non-uniformity of the irradiance over the multi-junction solar cells and different measurement techniques used to investigate them. To show the capabilities of the presented techniques, three different concentrators (that consist of an acrylic Fresnel lens, different SOEs and a lattice matched multi-junction cell) are evaluated. By employing these techniques is possible to answer some critical questions when designing concentrators as for example which degree of non-uniformity the cell can withstand, how critical the influence of series resistance is, or what kind of non-uniformity (spatial or spectral) causes more losses.

  6. Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Deng, X.; Jones, S.J.; Liu, T.; Izu, M. [Energy Conversion Devices, Inc., Troy, MI (United States)

    1998-04-01

    This report summarizes Energy Conversion Devices, Inc.`s (ECD) research under this program. ECD researchers explored the deposition of a-Si at high rates using very-high-frequency plasma MHz, and compared these VHF i-layers with radio-frequency (RF) plasma-deposited i-layers. ECD conducted comprehensive research to develop a {mu}c-Si p{sup +} layer using VHF deposition process with the objectives of establishing a wider process window for the deposition of high-quality p{sup +} materials and further enhancing their performance of a-Si solar cells by improving its p-layers. ECD optimized the deposition of the intrinsic a-Si layer and the boron-doped {mu}c-Si p{sup +} layer to improve the V{sub oc}. Researchers deposited wide-bandgap a-Si films using high hydrogen dilution; investigated the deposition of the ZnO layer (for use in back-reflector) using a sputter deposition process involving metal Zn targets; and obtained a baseline fabrication for single-junction a-Si n-i-p devices with 10.6% initial efficiency and a baseline fabrication for triple-junction a-Si devices with 11.2% initial efficiency. ECD researchers also optimized the deposition parameters for a-SiGe with high Ge content; designed a novel structure for the p-n tunnel junction (recombination layer) in a multiple-junction solar cell; and demonstrated, in n-i-p solar cells, the improved stability of a-Si:H:F materials when deposited using a new fluorine precursor. Researchers investigated the use of c-Si(n{sup +})/a-Si alloy/Pd Schottky barrier device as a tool for the effective evaluation of photovoltaic performance on a-Si alloy materials. Through alterations in the deposition conditions and system hardware, researchers improved their understanding for the deposition of uniform and high-quality a-Si and a-SiGe films over large areas. ECD researchers also performed extensive research to optimize the deposition process of the newly constructed 5-MW back-reflector deposition machine.

  7. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    International Nuclear Information System (INIS)

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact

  8. A Markov Chain Approach for Defining the Fundamental Efficiency Limits of Classical and Bifacial Multi-junction Tandem Solar Cells

    CERN Document Server

    Alam, Muhammad A

    2016-01-01

    Bifacial tandem cells promise to reduce three fundamental losses (above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction PV systems. The successive filtering of light through the bandgap cascade, and requirement of current continuity make optimization of tandem cells difficult, accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple Markov chain approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can obtained analytically with a few lines of algebra. This powerful approach reproduces, as special cases, all the known results of traditional/bifacial tandem cells, and highlights the asymptotic efficiency gain of these technologies.

  9. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    Energy Technology Data Exchange (ETDEWEB)

    Pathirane, M., E-mail: minoli.pathirane@uwaterloo.ca; Iheanacho, B.; Lee, C.-H.; Wong, W. S. [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Tamang, A.; Knipp, D. [Research Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Bremen 28759 (Germany); Lujan, R. [Electronic Materials and Devices Laboratory, Palo Alto Research Center, Palo Alto, California 93003 (United States)

    2015-10-05

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  10. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels.

    Science.gov (United States)

    Zhang, Yue; Yang, Wan-Xi

    2016-01-01

    Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs. PMID:27335757

  11. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

    Science.gov (United States)

    Zhang, Yue

    2016-01-01

    Summary Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs. PMID:27335757

  12. Autophagy and gap junctional intercellular communication inhibition are involved in cadmium-induced apoptosis in rat liver cells

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Hui [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China); Zhuo, Liling [College of Life Science, Zaozhuang University, Zaozhuang, Shandong, 277160 (China); Han, Tao; Hu, Di; Yang, Xiaokang; Wang, Yi; Yuan, Yan; Gu, Jianhong; Bian, Jianchun; Liu, Xuezhong [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China); Liu, Zongping, E-mail: liuzongping@yzu.edu.cn [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China)

    2015-04-17

    Cadmium (Cd) is known to induce hepatotoxicity, yet the underlying mechanism of how this occurs is not fully understood. In this study, Cd-induced apoptosis was demonstrated in rat liver cells (BRL 3A) with apoptotic nuclear morphological changes and a decrease in cell index (CI) in a time- and concentration-dependent manner. The role of gap junctional intercellular communication (GJIC) and autophagy in Cd-induced apoptosis was investigated. Cd significantly induced GJIC inhibition as well as downregulation of connexin 43 (Cx43). The prototypical gap junction blocker carbenoxolone disodium (CBX) exacerbated the Cd-induced decrease in CI. Cd treatment was also found to cause autophagy, with an increase in mRNA expression of autophagy-related genes Atg-5, Atg-7, Beclin-1, and microtubule-associated protein light chain 3 (LC3) conversion from cytosolic LC3-I to membrane-bound LC3-II. The autophagic inducer rapamycin (RAP) prevented the Cd-induced CI decrease, while the autophagic inhibitor chloroquine (CQ) caused a further reduction in CI. In addition, CBX promoted Cd-induced autophagy, as well as changes in expression of Atg-5, Atg-7, Beclin-1 and LC3. CQ was found to block the Cd-induced decrease in Cx43 and GJIC inhibition, whereas RAP had opposite effect. These results demonstrate that autophagy plays a protective role during Cd-induced apoptosis in BRL 3A cells during 6 h of experiment, while autophagy exacerbates Cd-induced GJIC inhibition which has a negative effect on cellular fate. - Highlights: • GJIC and autophagy is crucial for biological processes. • Cd exposure causes GJIC inhibition and autophagy increase in BRL 3A cells. • Autophagy protects Cd induced BRL 3A cells apoptosis at an early stage. • Autophagy exacerbates Cd-induced GJIC inhibition. • GJIC plays an important role in autophagy induced cell death or survival.

  13. Autophagy and gap junctional intercellular communication inhibition are involved in cadmium-induced apoptosis in rat liver cells

    International Nuclear Information System (INIS)

    Cadmium (Cd) is known to induce hepatotoxicity, yet the underlying mechanism of how this occurs is not fully understood. In this study, Cd-induced apoptosis was demonstrated in rat liver cells (BRL 3A) with apoptotic nuclear morphological changes and a decrease in cell index (CI) in a time- and concentration-dependent manner. The role of gap junctional intercellular communication (GJIC) and autophagy in Cd-induced apoptosis was investigated. Cd significantly induced GJIC inhibition as well as downregulation of connexin 43 (Cx43). The prototypical gap junction blocker carbenoxolone disodium (CBX) exacerbated the Cd-induced decrease in CI. Cd treatment was also found to cause autophagy, with an increase in mRNA expression of autophagy-related genes Atg-5, Atg-7, Beclin-1, and microtubule-associated protein light chain 3 (LC3) conversion from cytosolic LC3-I to membrane-bound LC3-II. The autophagic inducer rapamycin (RAP) prevented the Cd-induced CI decrease, while the autophagic inhibitor chloroquine (CQ) caused a further reduction in CI. In addition, CBX promoted Cd-induced autophagy, as well as changes in expression of Atg-5, Atg-7, Beclin-1 and LC3. CQ was found to block the Cd-induced decrease in Cx43 and GJIC inhibition, whereas RAP had opposite effect. These results demonstrate that autophagy plays a protective role during Cd-induced apoptosis in BRL 3A cells during 6 h of experiment, while autophagy exacerbates Cd-induced GJIC inhibition which has a negative effect on cellular fate. - Highlights: • GJIC and autophagy is crucial for biological processes. • Cd exposure causes GJIC inhibition and autophagy increase in BRL 3A cells. • Autophagy protects Cd induced BRL 3A cells apoptosis at an early stage. • Autophagy exacerbates Cd-induced GJIC inhibition. • GJIC plays an important role in autophagy induced cell death or survival

  14. Small renal cell carcinoma: CT and pathologic correlation

    International Nuclear Information System (INIS)

    Objective: To analyze the correlation of CT and pathological manifestation of small renal cell carcinoma (SRCC). Methods: Thirty-six SRCC were all diagnosed by surgical pathology. On CT, attenuation value and the amount of enhancement were observed; on pathology, tumor cell characteristics, cell arrangement, the stage and grade of the tumor et al were observed. Results: 31 tumors were iso- or hypo-attenuation on CT and clear cell tumors were dominant in 28 cases; 5 cases were hyper-attenuation and 2 of them were granular cell carcinoma. After the contrast enhancement, 31 tumors were enhanced more than 40 HU. 27 of them were solid which had abundant sinusoid vessels; Enhancement in 29 cases was heterogeneous, and on pathology, hemorrhage and necrosis were found in 27 of them. Conclusion: The CT findings of SRCC were correlated with tumor cell characteristic and architecture

  15. Point correlation dimension can reveal functional changes caused by gap junction blockers in the 4-aminopyridine in vivo rat epilepsy model

    Energy Technology Data Exchange (ETDEWEB)

    Jardanhazy, Anett [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary); Molnar, Mark [Department of Psychophysiology, Institute for Psychology of the Hungarian Academy of Sciences, P.O. Box 398, Budapest H-1394 (Hungary)], E-mail: molnar@cogpsyphy.hu; Jardanhazy, Tamas [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary)], E-mail: jt@nepsy.szote.u-szeged.hu

    2009-04-15

    The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.

  16. Point correlation dimension can reveal functional changes caused by gap junction blockers in the 4-aminopyridine in vivo rat epilepsy model

    International Nuclear Information System (INIS)

    The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.

  17. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    International Nuclear Information System (INIS)

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

  18. Quadruple-junction solar cells and modules based on amorphous and microcrystalline silicon with high stable efficiencies

    Science.gov (United States)

    Kirner, Simon; Neubert, Sebastian; Schultz, Christof; Gabriel, Onno; Stannowski, Bernd; Rech, Bernd; Schlatmann, Rutger

    2015-08-01

    Quadruple junction solar cells and modules are presented, which consist of hydrogenated amorphous (a-Si:H) and microcrystalline silicon (µc-Si:H) in the a-Si:H/a-Si:H/µc-Si:H/µc-Si:H configuration. The highest measured conversion efficiency of a mini-module with an aperture area of 61.44 cm2 was 13.4% before and 12.0% after more than 1000 h of light soaking, respectively. In this paper, we discuss the advantages of the quadruple junction design over the common tandem design, which is ascribed mainly to the fact that the total absorber thickness can be increased while electronic properties and stability are maintained or even improved. The role of the µc-SiOx:H intermediate reflector is highlighted and an optimization of the doping concentration in this layer is presented. Furthermore, the advantage of the high maximum power voltage for the monolithic cell interconnection laser design of modules is shown.

  19. SXPS characterization of a donor / acceptor hetero junction for organic solar cells: High photovoltage at the merocyanine / fullerene interface

    Energy Technology Data Exchange (ETDEWEB)

    Mankel, Eric; Reckers, Philip; Konrad, Ludmila; Hein, Corinna; Mayer, Thomas; Jaegermann, Wolfram [Technische Universitaet Darmstadt, Materials Science Institute, Surface Science Division, Petersenstrasse 32, 64287 Darmstadt (Germany)

    2011-07-01

    Novel absorber molecules are investigated for high efficient organic solar cells. Especially merocyanines provide high photovoltages as donor materials in photoactive organic hetero junction cells. The electronic alignment of a merocyanine/fullerene hetero junction is presented. The band diagram was determined by synchrotron induced photoelectron spectroscopy on in situ stepwise deposited fullerene on a merocyanine layer using the TGM7 dipole beamline at Bessy II. The merocyanine/fullerene HOMO offset is determined to be 850 meV leading to a high LUMO offset, the driving force for exciton splitting. In situ bias illumination of the interface with 150 W/m{sup 2} of a halogen lamp leads to a reversible shift of the C{sub 60} emission features of about 800 meV, indicating a high photovoltage. The height of the photovoltage depends on the fullerene layer thickness. It starts at 200 mV for submonolayer coverage and increases up to approximately 1V for coverages of some ten nanometers.

  20. Impact of many-body correlations on the dynamics of an ion-controlled bosonic Josephson junction

    Science.gov (United States)

    Schurer, J. M.; Gerritsma, R.; Schmelcher, P.; Negretti, A.

    2016-06-01

    We investigate an atomic ensemble of interacting bosons trapped in a symmetric double-well potential in contact with a single tightly trapped ion which has been recently proposed [R. Gerritsma et al., Phys. Rev. Lett. 109, 080402 (2012), 10.1103/PhysRevLett.109.080402] as a source of entanglement between a Bose-Einstein condensate and an ion. Compared to the previous study, the present work aims at performing a detailed and accurate many-body analysis of such a combined atomic quantum system by means of the ab initio multiconfiguration time-dependent Hartree method for bosons, which allows us to take into account all correlations in the system. The analysis elucidates the importance of quantum correlations in the bosonic ensemble and reveals that entanglement generation between an ion and a condensate is indeed possible, as previously predicted. Moreover, we provide an intuitive picture of the impact of the correlations on the out-of-equilibrium dynamics by employing a natural orbital analysis which we show to be indeed experimentally verifiable.

  1. Role of connexin (gap junction) genes in cell growth control and carcinogenesis; Role des jonctions intercellulaires dans la cancerogenese

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, H.; Krutovskikh, V.; Mesnil, M.; Tanaka, T.; Zaidan-Dagli, M.L.; Omori, Y. [International Agency for Research on Cancer, Lyon (France). Unit of Multistage Carcinogenesis

    1999-03-01

    Gap junctional intercellular communication (GJIC) is considered to play a key role in the maintenance of tissue independence and homeostasis in multicellular organisms by controlling the growth of GJIC-connected cells. Gap junction channels are composed of connexin molecules and, so far, more than a dozen different connexin genes have been shown to be expressed in mammals. Reflecting the importance of GJIC in various physiological functions, deletion of different connexin genes from mice results in various disorders, including cancers, heart malformation or conduction abnormality, cataract, etc. The possible involvement of aberrant GJIC in abnormal cell growth and carcinogenesis has long been postulated and recent studies in our own and other laboratories have confirmed that expression and function of connexin genes play an important role in cell growth control. Thus, almost all malignant cells show altered homologous and/or heterologous GJIC and are often associated with aberrant expression or localization of connexins. Aberrant localization of connexins in some tumour cells is associated with lack of function of cell adhesion molecules, suggesting the importance of cell-cell recognition for GJIC. Transfection of connexin genes into tumorigenic cells restores normal cell growth, supporting the idea that connexins form a family of tumour-suppressor genes. Some studies also show that specific connexins may be necessary to control growth of specific cell types. We have produced various dominant-negative mutants of Cx26, Cx32 and Cx43 and showed that some of them prevent the growth control exerted by the corresponding wild-type genes. However, we have found that connexins 32, 37 and 43 genes are rarely mutated in tumours. In some of these studies, we noted that connexin expression per se, rather than GJIC level, is more closely related to growth control, suggesting that connexins may have a GJIC-independent function. We have recently created a transgenic mouse strain

  2. Efficiency improvement of single-junction InGaP solar cells fabricated by a novel micro-hole array surface texture process

    International Nuclear Information System (INIS)

    In this study, single-junction InGaP solar cells fabricated by a novel micro-hole array surface texture process are presented. The characteristics of the single-junction InGaP solar cells with and without the micro-hole array surface texture are studied. An increase of 10.4% in short-circuit current is found when a single-junction InGaP solar cell is fabricated by the micro-hole array surface texture process. The conversion efficiency measured under one-sun air mass 1.5 global illumination at room temperature can also be improved from 13.8% to 15.9% when the size of the micro-holes is 5.3 µm and the period of micro-hole array is designed to 5 µm

  3. Genetic deletion of afadin causes hydrocephalus by destruction of adherens junctions in radial glial and ependymal cells in the midbrain.

    Directory of Open Access Journals (Sweden)

    Hideaki Yamamoto

    Full Text Available Adherens junctions (AJs play a role in mechanically connecting adjacent cells to maintain tissue structure, particularly in epithelial cells. The major cell-cell adhesion molecules at AJs are cadherins and nectins. Afadin binds to both nectins and α-catenin and recruits the cadherin-β-catenin complex to the nectin-based cell-cell adhesion site to form AJs. To explore the role of afadin in radial glial and ependymal cells in the brain, we generated mice carrying a nestin-Cre-mediated conditional knockout (cKO of the afadin gene. Newborn afadin-cKO mice developed hydrocephalus and died neonatally. The afadin-cKO brain displayed enlarged lateral ventricles and cerebral aqueduct, resulting from stenosis of the caudal end of the cerebral aqueduct and obliteration of the ventral part of the third ventricle. Afadin deficiency further caused the loss of ependymal cells from the ventricular and aqueductal surfaces. During development, radial glial cells, which terminally differentiate into ependymal cells, scattered from the ventricular zone and were replaced by neurons that eventually covered the ventricular and aqueductal surfaces of the afadin-cKO midbrain. Moreover, the denuded ependymal cells were only occasionally observed in the third ventricle and the cerebral aqueduct of the afadin-cKO midbrain. Afadin was co-localized with nectin-1 and N-cadherin at AJs of radial glial and ependymal cells in the control midbrain, but these proteins were not concentrated at AJs in the afadin-cKO midbrain. Thus, the defects in the afadin-cKO midbrain most likely resulted from the destruction of AJs, because AJs in the midbrain were already established before afadin was genetically deleted. These results indicate that afadin is essential for the maintenance of AJs in radial glial and ependymal cells in the midbrain and is required for normal morphogenesis of the cerebral aqueduct and ventral third ventricle in the midbrain.

  4. The nature of single-ion activity coefficients calculated from potentiometric measurements on cells with liquid junctions

    International Nuclear Information System (INIS)

    Highlights: → Problem of ionic activity coefficients, determined by potentiometry, is reconsidered. → They are found to be functions of mean activity coefficients and transport numbers of ions. → The finding is verified by calculations and comparing the results with reported data. → Calculations are performed for systems with single electrolytes and binary mixtures. - Abstract: Potentiometric measurements on cells with liquid junctions are sometimes used for calculations of single-ion activity coefficients in electrolyte solutions, the incidence of this being increased recently. As surmised by Guggenheim in the 1930s, such coefficients (of ions i), γi, are actually complicated functions of mean ionic activity coefficients, γ±, and transport numbers of ions, ti. In the present paper specific functions γi(γ±, ti) are derived for a number of cell types with an arbitrary mixture of strong electrolytes in a one-component solvent in the liquid-junction system. The cell types include cells with (i) identical electrodes, (ii) dissimilar electrodes reversible to the same ions, (iii) dissimilar electrodes reversible to ions of opposite charge signs, (iv) dissimilar electrodes reversible to different ions of the same charge sign, and (v) identical reference electrodes and an ion-selective membrane permeable to ions of only one type. Pairs of functions for oppositely charged ions are found to be consistent with the mean ionic activity coefficients as would be expected for pairs of the proper γi quantities by definition of γ±. The functions are tested numerically on some of the reported γi datasets that are the more tractable. A generally good agreement is found with data reported for cells with single electrolytes HCl and KCl in solutions, and with binary mixtures in the liquid-junction systems of KCl from the reference solutions and NaCl and HCl from the test solutions. It is found that values of γi(γ±, ti) functions, in general, do depend on the

  5. Mutation Analysis of Gap Junction Protein Beta 1 and Genotype-Phenotype Correlation in X-linked Charcot-Marie-Tooth Disease in Chinese Patients

    Institute of Scientific and Technical Information of China (English)

    Bo Sun; Zhao-Hui Chen; Li Ling; Yi-Fan Li; Li-Zhi Liu; Fei Yang; Xu-Sheng Huang

    2016-01-01

    Background:Among patients with Charcot-Marie-Tooth disease (CMT),the X-linked variant (CMTX) caused by gap junction protein beta 1 (GJB1) gene mutation is the second most frequent type,accounting for approximately 90% of all CMTX.More than 400 mutations have been identified in the GJB1 gene that encodes connexin 32 (CX32).CX32 is thought to form gap junctions that promote the diffusion pathway between cells.GJB1 mutations interfere with the formation of the functional channel and impair the maintenance of peripheral myelin,and novel mutations are continually discovered.Methods:We included 79 unrelated patients clinically diagnosed with CMT at the Department of Neurology of the Chinese People's Liberation Army General Hospital from December 20,2012,to December 31,2015.Clinical examination,nerve conduction studies,and molecular and bioinformatics analyses were performed to identify patients with CMTX 1.Results:Nine GJB1 mutations (c.283G>A,c.77C>T,c.643C>T,c.515C>T,c.191G>A,c.610C>T,c.490C>T,c.491G>A,and c.44G>A) were discovered in nine patients.Median motor nerve conduction velocities of all nine patients were < 38 m/s,resembling CMT Type 1.Three novel mutations,c.643C>T,c.191G>A,and c.610C>T,were revealed and bioinformatics analyses indicated high pathogenicity.Conclusions:The three novel missense mutations within the GJB1 gene broaden the mutational diversity of CMT 1 X.Molecular analysis of family members and bioinformatics analyses of the afflicted patients confirmed the pathogenicity of these mutations.

  6. IGF-I regulates tight-junction protein claudin-1 during differentiation of osteoblast-like MC3T3-E1 cells via a MAP-kinase pathway

    OpenAIRE

    HATAKEYAMA, Naoko; Kojima, Takashi; Iba, Kousuke; Murata, Masaki; Thi, Mia M.; SPRAY, DAVID C.; Osanai, Makoto; Chiba, Hideki; ISHIAI, Sumio; Yamashita, Toshihiko; Sawada, Norimasa

    2008-01-01

    Insulin-like growth factor I (IGF-I) is expressed in many tissues, including bone, and acts on the proliferation and differentiation of osteoblasts as an autocrine/paracrine regulator. Tight-junction proteins have been detected in osteoblasts, and direct cell-to-cell interactions may modulate osteoblast function with respect, for example, to gap junctions. In order to investigate the regulation of expression of tight-junction molecules and of function during bone differentiation, osteoblast-l...

  7. Antiproliferative Action of Conjugated Linoleic Acid on Human MCF-7 Breast Cancer Cells Mediated by Enhancement of Gap Junctional Intercellular Communication through Inactivation of NF-κB

    OpenAIRE

    Rakib, Md. Abdur; Lee, Won Sup; Kim, Gon Sup; Han, Jae Hee; Kim, Jeong Ok; Ha, Yeong Lae

    2013-01-01

    The major conjugated linoleic acid (CLA) isomers, c9,t11-CLA and t10,c12-CLA, have anticancer effects; however, the exact mechanisms underlying these effects are unknown. Evidence suggests that reversal of reduced gap junctional intercellular communication (GJIC) in cancer cells inhibits cell growth and induces cell death. Hence, we determined that CLA isomers enhance GJIC in human MCF-7 breast cancer cells and investigated the underlying molecular mechanisms. The CLA isomers significantly en...

  8. Antiproliferative Action of Conjugated Linoleic Acid on Human MCF-7 Breast Cancer Cells Mediated by Enhancement of Gap Junctional Intercellular Communication through Inactivation of NF- κ B

    OpenAIRE

    Md. Abdur Rakib; Won Sup Lee; Gon Sup Kim; Jae Hee Han; Jeong Ok Kim; Yeong Lae Ha

    2013-01-01

    The major conjugated linoleic acid (CLA) isomers, c9,t11-CLA and t10,c12-CLA, have anticancer effects; however, the exact mechanisms underlying these effects are unknown. Evidence suggests that reversal of reduced gap junctional intercellular communication (GJIC) in cancer cells inhibits cell growth and induces cell death. Hence, we determined that CLA isomers enhance GJIC in human MCF-7 breast cancer cells and investigated the underlying molecular mechanisms. The CLA isomers significantly en...

  9. Evaluation of the Correlation of (He Distance Between the Alveolar Crest and Cementoenamel Junction Inpreiapical. Bitewing and Panoramic Radiographs with its Actual Distance

    Directory of Open Access Journals (Sweden)

    J. Yazdani

    2005-02-01

    Full Text Available Statement of Problem: In spite of the limitations of Radiography, diagnosing of periodontal diseases without having accurate radiographs is inadequate because it provides a visible image of the supporting bone to the clinician and works as a fixed measure of the supporting bone during the study.Purpose: The aim of this study is to compare the precision of preiapical, bitewings and panoramicradiographs in determining the distance between the alveolar crest (AC and cementoenamel junction (CEJ of teeth. Materials and Methods: Statistically this is a survey study in which 120 interproximal surfaces of teeth were measured during surgery by periodontal probing and recorded as the actual measurement. Then 40 sites underwent bitewing, 40 sites preapical and 40 others panoramic radiography and the distance of CEJ up to the alveolar crest of bone was measured on them by periodontal probe and recorded. Then each group was analyzed separately and the Pearson's correlation coefficient was examined for the data.Results: The results of this study showed that when the thickness of the remaining bone in a millimeter limit is important for (he surgeon, the bitewing radiography has a prime importance, but when bone loss ismoderate, the panoramic radiography showing %89 of the cases close to the actual measure, can be acceptable. On the other hand, in anterior sites for determining the bone alteration, preiapical radiography with a 0.93 correlation coefficient is superior to the panoramic radiography with a correlation coefficient of 0.72 and we suggest it for examining the changes of bone in these sites. Conclusion: whenever the bone alteration is moderate or severe, it seems that, bitewing radiography is of particular importance, but when the bone loss is little, panoramic radiography can be used and there is no needto put the patient on unnecessary radiation.

  10. Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weiquan; Becker, Jacob; Liu, Shi; Kuo, Ying-Shen; Li, Jing-Jing; Zhang, Yong-Hang [Center for Photonics Innovation and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Landini, Barbara; Campman, Ken [Sumika Electronic Materials, Inc., Phoenix, Arizona 85034 (United States)

    2014-05-28

    This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In{sub 0.49}Ga{sub 0.51}P/GaAs/In{sub 0.49}Ga{sub 0.51}P double-heterostructure PN junction with an ultra-thin 300 nm thick GaAs absorber, combined with a 5 μm thick Al{sub 0.52}In{sub 0.48}P layer with a textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF{sub 2}/ZnS anti-reflective coating demonstrated open-circuit voltages (V{sub oc}) up to 1.00 V, short-circuit current densities (J{sub sc}) up to 24.5 mA/cm{sup 2}, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated J{sub sc} and conversion efficiency of these devices are expected to reach 26.6 mA/cm{sup 2} and 20.7%, respectively.

  11. Lecithin-Bound Iodine Prevents Disruption of Tight Junctions of Retinal Pigment Epithelial Cells under Hypoxic Stress

    Directory of Open Access Journals (Sweden)

    Masahiko Sugimoto

    2016-01-01

    Full Text Available Aim. We investigated whether lecithin-bound iodine (LBI can protect the integrity of tight junctions of retinal pigment epithelial cells from hypoxia. Method. Cultured human retinal pigment epithelial (ARPE-19 cells were pretreated with LBI. To mimic hypoxic conditions, cells were incubated with CoCl2. We compared the integrity of the tight junctions (TJs of control to cells with either LBI alone, CoCl2 alone, or LBI + CoCl2. The levels of cytokines in the conditioned media were also determined. Results. Significant decrease in the zonula occludens-1 (ZO-1 intensity in the CoCl2 group compared to the control (5787.7 ± 4126.4 in CoCl2 group versus 29244.6 ± 2981.2 in control; average ± standard deviation. But the decrease was not significant in the LBI + CoCl2 (27189.0 ± 11231.1. The levels of monocyte chemoattractant protein-1 (MCP-1 and Chemokine (C-C Motif Ligand 11 (CCL-11 were significantly higher in the CoCl2 than in the control (340.8 ± 43.3 versus 279.7 ± 68.3 pg/mL for MCP-1, and 15.2 ± 12.9 versus 12.5 ± 6.1 pg/mL for CCL-11. With LBI pretreatment, the levels of both cytokines were decreased to 182.6 ± 23.8 (MCP-1 and 5.46 ± 1.9 pg/mL for CCL-11. Blockade of MCP-1 or CCL-11 also shows similar result representing TJ protection from hypoxic stress. Conclusions. LBI results in a protective action from hypoxia.

  12. Cell Matrix Remodeling Ability Shown by Image Spatial Correlation

    Directory of Open Access Journals (Sweden)

    Chi-Li Chiu

    2013-01-01

    Full Text Available Extracellular matrix (ECM remodeling is a critical step of many biological and pathological processes. However, most of the studies to date lack a quantitative method to measure ECM remodeling at a scale comparable to cell size. Here, we applied image spatial correlation to collagen second harmonic generation (SHG images to quantitatively evaluate the degree of collagen remodeling by cells. We propose a simple statistical method based on spatial correlation functions to determine the size of high collagen density area around cells. We applied our method to measure collagen remodeling by two breast cancer cell lines (MDA-MB-231 and MCF-7, which display different degrees of invasiveness, and a fibroblast cell line (NIH/3T3. We found distinct collagen compaction levels of these three cell lines by applying the spatial correlation method, indicating different collagen remodeling ability. Furthermore, we quantitatively measured the effect of Latrunculin B and Marimastat on MDA-MB-231 cell line collagen remodeling ability and showed that significant collagen compaction level decreases with these treatments.

  13. Optimization of Recombination Layer in the Tunnel Junction of Amorphous Silicon Thin-Film Tandem Solar Cells

    Directory of Open Access Journals (Sweden)

    Yang-Shin Lin

    2011-01-01

    Full Text Available The amorphous silicon/amorphous silicon (a-Si/a-Si tandem solar cells have attracted much attention in recent years, due to the high efficiency and low manufacturing cost compared to the single-junction a-Si solar cells. In this paper, the tandem cells are fabricated by high-frequency plasma-enhanced chemical vapor deposition (HF-PECVD at 27.1 MHz. The effects of the recombination layer and the i-layer thickness matching on the cell performance have been investigated. The results show that the tandem cell with a p+ recombination layer and i2/i1 thickness ratio of 6 exhibits a maximum efficiency of 9.0% with the open-circuit voltage (Voc of 1.59 V, short-circuit current density (Jsc of 7.96 mA/cm2, and a fill factor (FF of 0.70. After light-soaking test, our a-Si/a-Si tandem cell with p+ recombination layer shows the excellent stability and the stabilized efficiency of 8.7%.

  14. Forward-bias capacitance and current measurements for determining lifetimes and band narrowing in p-n junction solar cells

    Science.gov (United States)

    Neugroschel, A.; Chen, P. J.; Pao, S. C.; Lindholm, F. A.

    1978-01-01

    A new method is described and illustrated for determining the minority-carrier diffusion length and lifetime in the base region of p-n junction solar cells. The method requires only capacitance measurements at the device terminals and its accuracy is estimated to be + or - 5%. It is applied to a set of silicon p-n junction devices and the values of the diffusion lengths agree with those obtained using the current response to X-ray excitation but disagree with those obtained by the OCVD method. The reasons for the relative inaccuracy of OCVD applied to silicon devices are discussed. The capacitance method includes corrections for a two-dimensional fringing effects which occur in small area devices. For a device having highly-doped base region and surface (emitter) layer, the method can be extended to enable the determination of material properties of the degenerately doped surface layer. These material properties include the phenomenological emitter lifetime and a measure of the energy band-gap narrowing in the emitter. An alternate method for determining the energy band-gap narrowing from temperature dependence of emitter current is discussed and demonstrated.

  15. Overexpression of galectin-7 in mouse epidermis leads to loss of cell junctions and defective skin repair.

    Directory of Open Access Journals (Sweden)

    Gaëlle Gendronneau

    Full Text Available The proteins of the galectin family are implicated in many cellular processes, including cell interactions, polarity, intracellular trafficking, and signal transduction. In human and mouse, galectin-7 is almost exclusively expressed in stratified epithelia, notably in the epidermis. Galectin-7 expression is also altered in several human tumors of epithelial origin. This study aimed at dissecting the consequences of galectin-7 overexpression on epidermis structure and functions in vivo.We established transgenic mice specifically overexpressing galectin-7 in the basal epidermal keratinocytes and analyzed the consequences on untreated skin and after UVB irradiation or mechanical injury.The intercellular cohesion of the epidermis is impaired in transgenic animals, with gaps developing between adjacent keratinocytes, associated with loss of adherens junctions. The epidermal architecture is aberrant with perturbations in the multilayered cellular organisation of the tissue, and structural defects in the basement membrane. These transgenic animals displayed a reduced re-epithelialisation potential following superficial wound, due to a defective collective migration of keratinocytes. Finally, a single mild dose of UVB induced an abnormal apoptotic response in the transgenic epidermis.These results indicate that an excess of galectin-7 leads to a destabilisation of adherens junctions associated with defects in epidermal repair. As this phenotype shares similarities with that of galectin-7 null mutant mice, we conclude that a critical level of this protein is required for maintaining proper epidermal homeostasis. This study brings new insight into the mode of action of galectins in normal and pathological situations.

  16. MIrExpress: A Database for Gene Coexpression Correlation in Immune Cells Based on Mutual Information and Pearson Correlation

    OpenAIRE

    Luman Wang; Qiaochu Mo; Jianxin Wang

    2015-01-01

    Most current gene coexpression databases support the analysis for linear correlation of gene pairs, but not nonlinear correlation of them, which hinders precisely evaluating the gene-gene coexpression strengths. Here, we report a new database, MIrExpress, which takes advantage of the information theory, as well as the Pearson linear correlation method, to measure the linear correlation, nonlinear correlation, and their hybrid of cell-specific gene coexpressions in immune cells. For a given ge...

  17. Current-voltage characteristic for bipolar p-n junction devices with drift fields, including correlation between carrier lifetimes and shallow-impurity concentration

    International Nuclear Information System (INIS)

    We present general analytic solutions for static current-voltage characteristics of quasineutral regions of nonilluminated semiconductor bipolar devices under the following assumptions: (a) the quasineutral region has a graded shallow-level impurity concentration producing a constant built-in electric (drift) field; (b) minority carriers injected into this region stay at concentrations low enough to avoid violation of low-injection conditions; (c) the minority-carrier lifetime of this region depends on position in accordance with a power-law dependence on the shallow-level donor concentration, a dependence that is consistent with the longest minority-carrier lifetimes measured and with the physical chemistry of divacancy-donor reactions at high temperatures. The solutions presented are apparently the first that include assumption (c). Modified Bessel functions of the first and second kind appear in these solutions. From a pheonomenological standpoint, the solutions may account for defect centers associated with vacancy complexes and, in part, for the gettering observed in highly doped n-type Si. Design implications for transistors, diodes, and solar cells are discussed quantitatively for a thin drift-field Si p/n(x) junction solar cell

  18. Cu2ZnSnS4 (CZTS) nanoparticle based nontoxic and earth-abundant hybrid pn-junction solar cells.

    Science.gov (United States)

    Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

    2012-06-14

    A heterojunction between a layer of CZTS nanoparticles and a layer of fullerene derivatives forms a pn-junction. We have used such an inorganic-organic hybrid pn-junction device for solar cell applications. As routes to optimize device performance, interdot separation has been reduced by replacing long-chain ligands of the quantum dots with short-chain ligands and thickness of the CZTS layer has been varied. We have shown that the CZTS-fullerene interface could dissociate photogenerated excitons due to the depletion region formed at the pn-junction. From capacitance-voltage characteristics, we have determined the width of the depletion region, and compared it with the parameters of devices based on the components of the heterojunction. The results demonstrate solar cell applications based on nontoxic and earth-abundant materials. PMID:22539133

  19. Novel role of zonula occludens-1: A tight junction protein closely associated with the odontoblast differentiation of human dental pulp cells.

    Science.gov (United States)

    Xu, Jue; Shao, Meiying; Pan, Hongying; Wang, Huning; Cheng, Li; Yang, Hui; Hu, Tao

    2016-07-01

    Zonula occludens-1 (ZO-1), a tight junction protein, contributes to the maintenance of the polarity of odontoblasts and junctional complex formation in odontoblast layer during tooth development. However, expression and possible role of ZO-1 in human dental pulp cells (hDPCs) during repair process remains unknown. Here, we investigated the expression of ZO-1 in hDPCs and the relationship with odontoblast differentiation. We found the processes of two adjacent cells were fused and formed junction-like structure using scanning electron microscopy. Fluorescence immunoassay and Western blot confirmed ZO-1 expression in hDPCs. Especially, ZO-1 was high expressed at the cell-cell junction sites. More interestingly, ZO-1 accumulated at the leading edge of lamellipodia in migrating cells when a scratch assay was performed. Furthermore, ZO-1 gradual increased during odontoblast differentiation and ZO-1 silencing greatly inhibited the differentiation. ZO-1 binds directly to actin filaments and RhoA/ROCK signaling mainly regulates cell cytoskeleton, thus RhoA/ROCK might play a role in regulating ZO-1. Lysophosphatidic acid (LPA) and Y-27632 were used to activate and inhibit RhoA/ROCK signaling, respectively, with or without mineralizing medium. In normal cultured hDPCs, RhoA activation increased ZO-1 expression and especially in intercellular contacts, whereas ROCK inhibition attenuated the effects induced by LPA. However, expression of ZO-1 was upregulated by Y-27632 but not significantly affected by LPA after odontoblast differentiation. Hence, ZO-1 highly expresses in cell-cell junctions and is related to odontoblast differentiation, which may contribute to dental pulp repair or even the formation of an odontoblast layer. RhoA/ROCK signaling is involved in the regulation of ZO-1. PMID:27109589

  20. Modulatory effects of cAMP and PKC activation on gap junctional intercellular communication among thymic epithelial cells

    Directory of Open Access Journals (Sweden)

    Neves-dos-Santos Sandra

    2010-01-01

    Full Text Available Abstract Background We investigated the effects of the signaling molecules, cyclic AMP (cAMP and protein-kinase C (PKC, on gap junctional intercellular communication (GJIC between thymic epithelial cells (TEC. Results Treatment with 8-Br-cAMP, a cAMP analog; or forskolin, which stimulates cAMP production, resulted in an increase in dye transfer between adjacent TEC, inducing a three-fold enhancement in the mean fluorescence of coupled cells, ascertained by flow cytometry after calcein transfer. These treatments also increased Cx43 mRNA expression, and stimulated Cx43 protein accumulation in regions of intercellular contacts. VIP, adenosine, and epinephrine which may also signal through cyclic nucleotides were tested. The first two molecules did not mimic the effects of 8-Br-cAMP, however epinephrine was able to increase GJIC suggesting that this molecule functions as an endogenous inter-TEC GJIC modulators. Stimulation of PKC by phorbol-myristate-acetate inhibited inter-TEC GJIC. Importantly, both the enhancing and the decreasing effects, respectively induced by cAMP and PKC, were observed in both mouse and human TEC preparations. Lastly, experiments using mouse thymocyte/TEC heterocellular co-cultures suggested that the presence of thymocytes does not affect the degree of inter-TEC GJIC. Conclusions Overall, our data indicate that cAMP and PKC intracellular pathways are involved in the homeostatic control of the gap junction-mediated communication in the thymic epithelium, exerting respectively a positive and negative role upon cell coupling. This control is phylogenetically conserved in the thymus, since it was seen in both mouse and human TEC preparations. Lastly, our work provides new clues for a better understanding of how the thymic epithelial network can work as a physiological syncytium.

  1. Effects of H pylori infection on gap-junctional intercellular communication and proliferation of gastric epithelial cells in vitro

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To explore the effects of H pylori infection on gap-junctional intercellular communication (GJIC) and proliferation of gastric epithelial cells in vitro. METHODS: A human gastric epithelial cell line (SGC-7901) cultured on coverslips was exposed overnight to intact H pylori (CagA+ or CagA- strains) and sonicated extracts, respectively. GJIC between the cells was detected by fluorescence redistribution after photobleaching (FRAP) technique. Proliferation of SGC cells was determined by methylthiazolyl tetrazolium (MTT)assay.RESULTS: When compared with control in which cells were cultured with simple medium alone, both CagA+ and CagA- H pylori isolates could inhibit GJIC (CagA+:F = 57.98, P < 0.01; CagA-: F = 29.59, P < 0.01) and proliferation (CagA+: F = 42.65, P < 0.01; CagA-: F =58.14, P < 0.01) of SGC-7901 cells. Compared with CagA- strains, CagA+ H pylori more significantly downregulated GJIC of gastric cells (intact H pylori: t = 13.86,P < 0.01; sonicated extracts: t = 11.87, P < 0.01) and inhibited proliferation gastric cells to a lesser extent in vitro (intact H pylori: t = 3.06, P < 0.05; sonicated extracts: t = 3.94, P < 0.01).CONCLUSION: Compared with CagA- H pylori strains,CagA+ strains down-regulate GJIC of gastric epithelial cells more significantly and inhibit proliferation of gastric cells to a lesser extent in vitro. H pylori, especially CagA+ strains, may play an important role in gastric carcinogenesis.

  2. Doping evaluation of InP nanowires for tandem junction solar cells

    Science.gov (United States)

    Lindelöw, F.; Heurlin, M.; Otnes, G.; Dagytė, V.; Lindgren, D.; Hultin, O.; Storm, K.; Samuelson, L.; Borgström, M.

    2016-02-01

    In order to push the development of nanowire-based solar cells further using optimized nanowire diameter and pitch, a doping evaluation of the nanowire geometry is necessary. We report on a doping evaluation of n-type InP nanowires with diameters optimized for light absorption, grown by the use of metal-organic vapor phase epitaxy in particle-assisted growth mode using tetraethyltin (TESn) as the dopant precursor. The charge carrier concentration was evaluated using four-probe resistivity measurements and spatially resolved Hall measurements. In order to reach the highest possible nanowire doping level, we set the TESn molar fraction at a high constant value throughout growth and varied the trimethylindium (TMIn) molar fraction for different runs. Analysis shows that the charge carrier concentration in nanowires grown with the highest TMIn molar fraction (not leading to kinking nanowires) results in a low carrier concentration of approximately 1016 cm-3. By decreasing the molar fraction of TMIn, effectively increasing the IV/III ratio, the carrier concentration increases up to a level of about 1019 cm-3, where it seems to saturate. Axial carrier concentration gradients along the nanowires are found, which can be correlated to a combination of changes in the nanowire growth rate, measured in situ by optical reflectometry, and polytypism of the nanowires observed in transmission electron microscopy.

  3. Connexin43-containing gap junctions potentiate extracellular Ca²⁺-induced odontoblastic differentiation of human dental pulp stem cells via Erk1/2.

    Science.gov (United States)

    Li, Shiting; He, Haitao; Zhang, Gang; Wang, Fei; Zhang, Ping; Tan, Yinghui

    2015-10-15

    Extracellular Ca(2+) can promote dentin sialophosphoprotein (DSPP) expression and odontoblastic differentiation of dental pulp stem cells (DPSCs). Gap junctions mediated by connexin43 (Cx43) allow diffusion of small molecules (such as Ca(2+)) among cells to regulate cell-to-cell communications. However, it is unclear whether Cx43 is required for the Ca(2+)-induced cell differentiation. Here, we found that the influx of extracellular Ca(2+) through L-type Ca(2+) channels increases intracellular free Ca(2+) levels to promote DSPP expression. Cx43 overexpression potentiated the extracellular Ca(2+)-induced DSPP expression via Erk1/2. Flow cytometry analyses showed that Cx43 increased the percentage of p-Erk1/2 positive cells in response to Ca(2+), indicating that Cx43 in DPSCs possibly acts as a traditional gap junction channel, which permits the sharing of signals among coupled cells to make more DPSCs respond to Ca(2+). Furthermore, inhibition of Cx43 function and gap junction communication decreased Ca(2+)-induced the expression of DSPP, suggesting that cell-to-cell contacts are required for Cx43 to promote the Ca(2+)-induced cell differentiation. Similarly, the study performed on DPSCs cultured at low-density and high-density revealed that intercellular contacts are required to potentiate Erk1/2 activity and DSPP expression. In total, this study indicates that Cx43 increases Ca(2+)-induced DSPP expression and odontoblastic differentiation of DPSCs via Erk1/2 through gap junction-mediated cell-to-cell contacts. PMID:26376117

  4. Characterization of the spatial distribution of irradiance and spectrum in concentrating photovoltaic systems and their effect on multi-junction solar cells

    OpenAIRE

    Victoria Pérez, Marta; Herrero Martin, Rebeca; Domínguez Domínguez, César; Anton Hernandez, Ignacio; Askins, Stephen; Sala Pano, Gabriel

    2011-01-01

    The irradiance and spectral distribution cast on the cell by a concentrating photovoltaic system, typically made up of a primary Fresnel lens and a secondary stage optical element, is dependent on many factors, and these distributions in turn influence the electrical performance of the cell. In this paper, the effect of spatial and spectral non-uniform irradiance distribution on multi-junction solar cell performance was analyzed using an integrated approach. Irradiance and spectral distributi...

  5. Significance and prognostic value of lysosomal enzyme activities measured in surgically operated adenocarcinomas of the gastroesophageal junction and squamous cell carcinomas of the lower third of esophagus

    Institute of Scientific and Technical Information of China (English)

    Aron Altorjay; Balazs Paal; Nicolette Sohar; Janos Kiss; Imre Szanto; Istvan Sohar

    2005-01-01

    AIM: To establish whether there are fundamental differences in the biochemistries of adenocarcinomas of the gastroesophageal junction (GEJ) and the squamous cell carcinomas of the lower third of the esophagus (LTE).METHODS: Between February 1, 1997 and February 1,2000, we obtained tissue samples at the moment of resection from 54 patients for biochemical analysis. The full set of data could be comprehensively analyzed in 47 of 54 patients' samples (81%). Of these, 29 were adenocarcinomas of the GEJ Siewert type Ⅰ (n = 8), type Ⅱ (n = 12), type Ⅲ (n = 9), and 18 presented as squamous cell carcinomas of the LTE. We evaluated the mean values of 11-lysosomal enzyme and 1-cytosol protease activities of the tumorous and surrounding mucosae as well as their relative activities, measured as the ratio of activity in tumor and normal tissues from the same patient.These data were further analyzed to establish the correlation with tumor localization, TNM stage (lymph-node involvement), histological type (papillary, signet-ring cell,tubular), state of differentiation (good, moderate, poor),and survival (≤24 or ≥24 mo).RESULTS: In adenocarcinomas, the activity of α-mannosidase (AMAN), cathepsin B (CB) and dipeptidyl-peptidase Ⅰ (DPP Ⅰ) increased significantly as compared to the normal gastric mucosa. In squamous cell carcinomas of the esophagus, we also found a significant difference in the activity of cathepsin L and tripeptidyl-peptidase I in addition to these three. There was a statistical correlation of AMAN,CB, and DPP Ⅰ activity between the level of differentiation of adenocarcinomas of the GEJ and lymph node involvement,because tumors with no lymph node metastases histologically confirmed as well-differentiated, showed a significantly lower activity. The differences in CB and DPP Ⅰ activity correlated well with the differences in survival rates, since the CB and DPP Ⅰ values of those who died within 24 mo following surgical intervention were

  6. Do the expressions of gap junction gene connexin messenger RNA in noncancerous liver remnants of patients with hepatocellular carcinoma correlate with postoperative recurrences?

    Institute of Scientific and Technical Information of China (English)

    I-Shyan Sheen; Kuo-Shyang Jeng; Shou-Chuan Shih; Chin-Roa Kao; Po-Chuan Wang; Chih-Zen Chen; Wen-Hsing Chang; Horng-Yuan Wang; Li-Rung Shyung

    2005-01-01

    AIM: To investigate whether the changes of gap junction gene connexin messenger RNA in the noncancerous liver tissue of patients with hepatocellular carcinoma (HCC) could play a significant role in its postresection recurrence.METHODS: Seventy-nine consecutive patients having undergone curative resection for HCC entered this study.Using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay, connexin (Cx) 26, connexin (Cx)32 and connexin (Cx) 43 mRNAs were determined prospectively in noncancerous liver tissues from these 79 patients and in the liver tissues from 15 controls. The correlations between connexin mRNA expression and the clinicopathological variables and outcomes (tumor recurrence and recurrence related mortality) were studied.RESULTS: Compared with liver tissues of control patients,the expression of Cx 32 mRNA in noncancerous liver tissues was significantly lower (mean: 0.715 vscontrol 1.225,P<0.01), whereas the decreased Cx 26 mRNA (mean:0.700 vs of control 1.205,P>0.05) and increased Cx 43 mRNA (mean: 0.241 vscontrol 0.100, P>0.05) had no statistical significance. We defined the value of Cx 32 mRNA or Cx 26mRNA below 0.800 as a lower value. By multivariate analysis for noncancerous livers, a lower value of Cx 32 mRNA correlated significantly with a risk of HCC recurrence and recurrence-related mortality. The lower value of Cx 26 mRNA did not correlate with recurrence and mortality. The increased value of Cx43 mRNA also did not correlate with postoperative recurrence and recurrence-related mortality. By multivariate analysis, other significant predictors of HCC recurrence included vascular permeation, cellular dedifferentiation, and less encaps-ulation. The other significant parameter of recurrence related mortality was vascular permeation.CONCLUSION: The decreased expression of Cx 32 mRNA in noncancerous liver tissues plays a significant role in the prediction of postoperative recurrence of HCC.

  7. Efficiently Harvesting Sun Light for Silicon Solar Cells through Advanced Optical Couplers and A Radial p-n Junction Structure

    Directory of Open Access Journals (Sweden)

    Hsin-Cheng Lee

    2010-04-01

    Full Text Available Silicon-based solar cells (SCs promise to be an alternative energy source mainly due to: (1 a high efficiency-to-cost ratio, (2 the absence of environmental-degradation issues, and (3 great reliability. Transition from wafer-based to thin-film SC significantly reduces the cost of SCs, including the cost from the material itself and the fabrication process. However, as the thickness of the absorption (or the active layer decreases, the energy-conversion efficiency drops dramatically. As a consequence, we discuss here three techniques to increase the efficiency of silicon-based SCs: (1 photonic crystal (PC optical couplers and (2 plasmonic optical couplers to increase efficiency of light absorption in the SCs, and (3 a radial p-n junction structure, decomposing light absorption and diffusion path into two orthogonal directions. The detailed mechanisms and recent research progress regarding these techniques are discussed in this review article.

  8. The cellular prion protein PrP(c is involved in the proliferation of epithelial cells and in the distribution of junction-associated proteins.

    Directory of Open Access Journals (Sweden)

    Etienne Morel

    Full Text Available BACKGROUND: The physiological function of the ubiquitous cellular prion protein, PrP(c, is still under debate. It was essentially studied in nervous system, but poorly investigated in epithelial cells. We previously reported that PrP(c is targeted to cell-cell junctions of polarized epithelial cells, where it interacts with c-Src. METHODOLOGY/FINDINGS: We show here that, in cultured human enterocytes and in intestine in vivo, the mature PrP(c is differentially targeted either to the nucleus in dividing cells or to cell-cell contacts in polarized/differentiated cells. By proteomic analysis, we demonstrate that the junctional PrP(c interacts with cytoskeleton-associated proteins, such as gamma- and beta-actin, alpha-spectrin, annexin A2, and with the desmosome-associated proteins desmoglein, plakoglobin and desmoplakin. In addition, co-immunoprecipitation experiments revealed complexes associating PrP(c, desmoglein and c-Src in raft domains. Through siRNA strategy, we show that PrP(c is necessary to complete the process of epithelial cell proliferation and for the sub-cellular distribution of proteins involved in cell architecture and junctions. Moreover, analysis of the architecture of the intestinal epithelium of PrP(c knock-out mice revealed a net decrease in the size of desmosomal junctions and, without change in the amount of BrdU incorporation, a shortening of the length of intestinal villi. CONCLUSIONS/SIGNIFICANCE: From these results, PrP(c could be considered as a new partner involved in the balance between proliferation and polarization/differentiation in epithelial cells.

  9. In vitro adherence patterns of Shigella serogroups to bovine recto-anal junction squamous epithelial (RSE) cells are similar to those of Escherichia coli O157

    Science.gov (United States)

    The aim of this study was to determine whether Shigella species, which are human gastrointestinal pathogens, can adhere to cattle recto-anal junction squamous epithelial (RSE) cells using a recently standardized adherence assay, and to compare their adherence patterns to that of Escherichia coli O15...

  10. Contorted hexabenzocoronene derivatives enable fullerene-free, semi-transparent solar cells with record-breaking single-junction photovoltage

    Science.gov (United States)

    Davy, Nicholas; Sezen, Melda; Loo, Yueh-Lin

    Recent work on tuning the chemical structure of contorted hexabenzocoronene (cHBC) in our group has yielded derivatives with a spectrum of energy levels and absorption profiles, greatly improving the utility of these materials as donor and/or acceptor constituents in organic solar cells. Here, we report planar-heterojunction solar cells comprising an extended heterocyclic cHBC donor and a halogenated cHBC acceptor. By harvesting primarily near-UV light, these devices exhibit a record open-circuit voltage of 1.5 V; this value is higher than any previously reported value for a single-junction organic solar cell. Our active layers are molecularly smooth and pinhole-free; these devices should be scalable to large areas without incurring substantial loss to performance. With a transmittance of 79% across the visible, our devices can be vertically integrated to directly drive the switching of electrochromic windows, where existing prototypes depend on tandem solar cells having near-infrared absorbers.

  11. Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

    Institute of Scientific and Technical Information of China (English)

    LIU Lei; CHEN NuoFu; BAI YiMing; CUI Ming; ZHANG Han; GAO FuBao; YIN ZhiGang; ZHANG XingWang

    2009-01-01

    GalnP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition (MOCVD) technique. Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160℃. The results indicate that the quantum ef-ficiencies of the subcells increase slightly with the increasing temperature. And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell's work temperature, which are consistent with the viewpoint of energy gap narrowing effect. The short-circuit current density tem-perature coefficients dJoc/dT of GalnP subcell and GaAs subcell are determined to be 8.9 and 7.4 μA/cm2/℃ from the quantum efficiency data, respectively. And the open-circuit cell voltage temperature coefficients d Voc/d T calculated based on a theoretical equation are -2.4 mV/℃ and -2.1 mV/℃ for GalnP subcell and GaAs subcell.

  12. Inhibiting Invasion into Human Bladder Carcinoma 5637 Cells with Diallyl Trisulfide by Inhibiting Matrix Metalloproteinase Activities and Tightening Tight Junctions

    Directory of Open Access Journals (Sweden)

    Yung Hyun Choi

    2013-10-01

    Full Text Available Diallyl trisulfide (DATS, an organosulfur compound in garlic, possesses pronounced anti-cancer potential. However, the anti-invasive mechanism of this compound in human bladder carcinoma is not fully understood. In this study, we evaluated the anti-invasive effects of DATS on a human bladder carcinoma (5637 cell line and investigated the underlying mechanism. The results indicated that DATS suppressed migration and invasion of 5637 cells by reducing the activities and expression of matrix metalloproteinase (MMP-2 and MMP-9 at both the protein and mRNA levels. DATS treatment up-regulated expression of tissue inhibitor of metalloproteinase (TIMP-1 and TIMP-2 in 5637 cells. The inhibitory effects of DATS on invasiveness were associated with an increase in transepithelial electrical resistance and repression of the levels of claudin family members. Although further studies are needed, our data demonstrate that DATS exhibits anti-invasive effects in 5637 cells by down-regulating the activity of tight junctions and MMPs. DATS may have future utility in clinical applications for treating bladder cancer.

  13. Aberrant expression of Cx43 is associated with the peritoneal metastasis of gastric cancer and Cx43-mediated gap junction enhances gastric cancer cell diapedesis from peritoneal mesothelium.

    Directory of Open Access Journals (Sweden)

    Bo Tang

    Full Text Available The process of peritoneal metastasis involves the diapedesis of intra-abdominal exfoliated gastric cancer cells through the mesothelial cell monolayers; however, the related molecular mechanisms for this process are still unclear. Heterocellular gap-junctional intercellular communication (GJIC between gastric cancer cells and mesothelial cells may play an active role during diapedesis. In this study we detected the expression of connexin 43 (Cx43 in primary gastric cancer tissues, intra-abdominal exfoliated cancer cells, and matched metastatic peritoneal tissues. We found that the expression of Cx43 in primary gastric cancer tissues was significantly decreased; the intra-abdominal exfoliated cancer cells and matched metastatic peritoneal tissues exhibited increasing expression compared with primary gastric cancer tissues. BGC-823 and SGC-7901 human gastric cancer cells were engineered to express Cx43 or Cx43T154A (a mutant protein that only couples gap junctions but provides no intercellular communication and were co-cultured with human peritoneal mesothelial cells (HPMCs. Heterocellular GJIC and diapedesis through HPMC monolayers on matrigel-coated coverslips were investigated. We found that BGC-823 and SGC-7901 gastric cancer cells expressing Cx43 formed functional heterocellular gap junctions with HPMC monolayers within one hour. A significant increase in diapedesis was observed in engineered Cx43-expressing cells compared with Cx43T154A and control group cells, which suggested that the observed upregulation of diapedesis in Cx43-expressing cells required heterocellular GJIC. Further study revealed that the gastric cancer cells transmigrated through the intercellular space between the mesothelial cells via a paracellular route. Our results suggest that the abnormal expression of Cx43 plays an essential role in peritoneal metastasis and that Cx43-mediated heterocellular GJIC between gastric cancer cells and mesothelial cells may be an

  14. Giant Cell Tumor Presenting as A Spindle Shaped Tumor Arising From the Costovertebral Junction at D7, d8, d9 Levels

    Science.gov (United States)

    Upadhyaya, Mihir; Kale, Sachin; Chaudhary, Prasad; Dhar, Sanjay

    2016-01-01

    Introduction: Giant cell tumor accounts for 5 to 9 percent of all primary bony tumors. Giant cell tumors are usually found in the long bones, most often the distal femur, proximal tibia, distal radius and rarely arising from the ribs. In this paper, we describe a case of giant cell tumor presented at an unusual location of the costovertebral junction as a dumbbell shaped tumor. Case Report: Authors report a case of a 27 year old male patient with a giant cell tumor arising from the costovertebral junction at D7, D8, and D9 levels compressing the cord. Well-defined osteolysis with nonsclerotic borders were visualized on radiographs and CT scan images. Intermediate signal intensity on T1 sequences and central high signal and peripheral intermediate signal intensity on T2 sequences was visualized on MRI images. CT guided biopsy was reported as a moderately vascular lesion with spindle cell neoplasm suggestive of schwannoma. The cord was decompressed, tumor mass was surgically resected and stabilization with instrumentation was done. Histopatholgy was suggestive of giant cell tumor. Conclusion: Giant cell tumor may be included in the differential diagnosis in a well-defined lytic lesion when involving the costovertebral junction presenting as a spindle cell tumor on biopsy reports. PMID:27299118

  15. Reinforcing endothelial junctions prevents microvessel permeability increase and tumor cell adhesion in microvessels in vivo

    OpenAIRE

    Bingmei M Fu; Jinlin Yang; Bin Cai; Jie Fan; Lin Zhang; Min Zeng

    2015-01-01

    Tumor cell adhesion to the microvessel wall is a critical step during tumor metastasis. Vascular endothelial growth factor (VEGF), a secretion of tumor cells, can increase microvessel permeability and tumor cell adhesion in the microvessel. To test the hypothesis that inhibiting permeability increase can reduce tumor cell adhesion, we used in vivo fluorescence microscopy to measure both microvessel permeability and adhesion rates of human mammary carcinoma MDA-MB-231 cells in post-capillary v...

  16. Breast cancer cell migration is regulated through junctional adhesion molecule-A-mediated activation of Rap1 GTPase

    LENUS (Irish Health Repository)

    McSherry, Elaine A

    2011-03-23

    Abstract Introduction The adhesion protein junctional adhesion molecule-A (JAM-A) regulates epithelial cell morphology and migration, and its over-expression has recently been linked with increased risk of metastasis in breast cancer patients. As cell migration is an early requirement for tumor metastasis, we sought to identify the JAM-A signalling events regulating migration in breast cancer cells. Methods MCF7 breast cancer cells (which express high endogenous levels of JAM-A) and primary cultures from breast cancer patients were used for this study. JAM-A was knocked down in MCF7 cells using siRNA to determine the consequences for cell adhesion, cell migration and the protein expression of various integrin subunits. As we had previously demonstrated a link between the expression of JAM-A and β1-integrin, we examined activation of the β1-integrin regulator Rap1 GTPase in response to JAM-A knockdown or functional antagonism. To test whether JAM-A, Rap1 and β1-integrin lie in a linear pathway, we tested functional inhibitors of all three proteins separately or together in migration assays. Finally we performed immunoprecipitations in MCF7 cells and primary breast cells to determine the binding partners connecting JAM-A to Rap1 activation. Results JAM-A knockdown in MCF7 breast cancer cells reduced adhesion to, and migration through, the β1-integrin substrate fibronectin. This was accompanied by reduced protein expression of β1-integrin and its binding partners αV- and α5-integrin. Rap1 activity was reduced in response to JAM-A knockdown or inhibition, and pharmacological inhibition of Rap1 reduced MCF7 cell migration. No additive anti-migratory effect was observed in response to simultaneous inhibition of JAM-A, Rap1 and β1-integrin, suggesting that they lie in a linear migratory pathway. Finally, in an attempt to elucidate the binding partners putatively linking JAM-A to Rap1 activation, we have demonstrated the formation of a complex between JAM-A, AF-6

  17. Breast cancer cell migration is regulated through junctional adhesion molecule-A-mediated activation of Rap1 GTPase.

    LENUS (Irish Health Repository)

    McSherry, Elaine A

    2011-03-23

    ABSTRACT: INTRODUCTION: The adhesion protein junctional adhesion molecule-A (JAM-A) regulates epithelial cell morphology and migration, and its over-expression has recently been linked with increased risk of metastasis in breast cancer patients. As cell migration is an early requirement for tumor metastasis, we sought to identify the JAM-A signalling events regulating migration in breast cancer cells. METHODS: MCF7 breast cancer cells (which express high endogenous levels of JAM-A) and primary cultures from breast cancer patients were used for this study. JAM-A was knocked down in MCF7 cells using siRNA to determine the consequences for cell adhesion, cell migration and the protein expression of various integrin subunits. As we had previously demonstrated a link between the expression of JAM-A and β1-integrin, we examined activation of the β1-integrin regulator Rap1 GTPase in response to JAM-A knockdown or functional antagonism. To test whether JAM-A, Rap1 and β1-integrin lie in a linear pathway, we tested functional inhibitors of all three proteins separately or together in migration assays. Finally we performed immunoprecipitations in MCF7 cells and primary breast cells to determine the binding partners connecting JAM-A to Rap1 activation. RESULTS: JAM-A knockdown in MCF7 breast cancer cells reduced adhesion to, and migration through, the β1-integrin substrate fibronectin. This was accompanied by reduced protein expression of β1-integrin and its binding partners αV- and α5-integrin. Rap1 activity was reduced in response to JAM-A knockdown or inhibition, and pharmacological inhibition of Rap1 reduced MCF7 cell migration. No additive anti-migratory effect was observed in response to simultaneous inhibition of JAM-A, Rap1 and β1-integrin, suggesting that they lie in a linear migratory pathway. Finally, in an attempt to elucidate the binding partners putatively linking JAM-A to Rap1 activation, we have demonstrated the formation of a complex between JAM-A, AF

  18. Breast cancer cell migration is regulated through junctional adhesion molecule-A-mediated activation of Rap1 GTPase.

    LENUS (Irish Health Repository)

    McSherry, Elaine A

    2012-02-01

    INTRODUCTION: The adhesion protein junctional adhesion molecule-A (JAM-A) regulates epithelial cell morphology and migration, and its over-expression has recently been linked with increased risk of metastasis in breast cancer patients. As cell migration is an early requirement for tumor metastasis, we sought to identify the JAM-A signalling events regulating migration in breast cancer cells. METHODS: MCF7 breast cancer cells (which express high endogenous levels of JAM-A) and primary cultures from breast cancer patients were used for this study. JAM-A was knocked down in MCF7 cells using siRNA to determine the consequences for cell adhesion, cell migration and the protein expression of various integrin subunits. As we had previously demonstrated a link between the expression of JAM-A and beta1-integrin, we examined activation of the beta1-integrin regulator Rap1 GTPase in response to JAM-A knockdown or functional antagonism. To test whether JAM-A, Rap1 and beta1-integrin lie in a linear pathway, we tested functional inhibitors of all three proteins separately or together in migration assays. Finally we performed immunoprecipitations in MCF7 cells and primary breast cells to determine the binding partners connecting JAM-A to Rap1 activation. RESULTS: JAM-A knockdown in MCF7 breast cancer cells reduced adhesion to, and migration through, the beta1-integrin substrate fibronectin. This was accompanied by reduced protein expression of beta1-integrin and its binding partners alphaV- and alpha5-integrin. Rap1 activity was reduced in response to JAM-A knockdown or inhibition, and pharmacological inhibition of Rap1 reduced MCF7 cell migration. No additive anti-migratory effect was observed in response to simultaneous inhibition of JAM-A, Rap1 and beta1-integrin, suggesting that they lie in a linear migratory pathway. Finally, in an attempt to elucidate the binding partners putatively linking JAM-A to Rap1 activation, we have demonstrated the formation of a complex between

  19. Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    GaInP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition(MOCVD) technique.Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160 ℃.The results indicate that the quantum ef-ficiencies of the subcells increase slightly with the increasing temperature.And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell’s work temperature,which are consistent with the viewpoint of energy gap narrowing effect.The short-circuit current density tem-perature coefficients dJsc/dT of GaInP subcell and GaAs subcell are determined to be 8.9 and 7.4 μA/cm2/℃ from the quantum efficiency data,respectively.And the open-circuit cell voltage temperature coefficients dVoc/dT calculated based on a theoretical equation are-2.4 mV/℃ and-2.1 mV/℃ for GaInP subcell and GaAs subcell.

  20. Analysis of Thermal Losses for a Variety of Single-Junction Photovoltaic Cells: An Interesting Means of Thermoelectric Heat Recovery

    Science.gov (United States)

    Lorenzi, Bruno; Acciarri, Maurizio; Narducci, Dario

    2015-06-01

    Exploitation of solar energy conversion has become a fundamental aspect of satisfying a growing demand for energy. Thus, improvement of the efficiency of conversion in photovoltaic (PV) devices is highly desirable to further promote this source. Because it is well known that the most relevant efficiency constraint, especially for single-junction solar cells, is unused heat within the device, hybrid thermo-photovoltaic systems seem promising . Among several hybrid solutions proposed in the literature, coupling of thermoelectric and PV devices seems one of the most interesting. Taking full advantage of this technology requires proper definition and analysis of the thermal losses occurring in PV cells. In this communication we propose a novel analysis of such losses, decoupling source-dependent and absorber-dependent losses. This analysis enables an evaluation of the actual recoverable amount of energy, depending on the absorber used in the PV cell. It shows that for incoming solar irradiation of , and depending on the choice of material, the maximum available thermal power ranges from (for single-crystal silicon) to (for amorphous silicon).

  1. Photovoltaic performance of thin-film CdS-Cu2S solar cells with electroformed junctions

    Science.gov (United States)

    Rastogi, A. C.

    1985-06-01

    Irreproducibility and low conversion efficiency of CdS-Cu2S solar cells fabricated by the chemiplating process are found to be the result of variations in the surface morphology of the textured CdS surface. To counter such problems, a new technique of barrier formation using direct-current (DC) field-assisted control over the reacting ionic species is described. Photovoltaic data on solar cells fabricated in this way display an overall improvement owing to the prevention of deep-intruded Cu(2-x)S growth along the CdS grain boundaries and a closer approximation to stoichiometry. In addition, with the use of the DC potential as a first-order variable these improved characteristics of the junctions have been found to be less sensitive to the Cu(2-x)S deposition variables, thus improving general reproducibility. Data on the cells made by the new technique obtained from spectral response, sheet resistivity, and accelerated life tests are presented.

  2. p-n junction improvements of Cu2ZnSnS4/CdS monograin layer solar cells

    Science.gov (United States)

    Kauk-Kuusik, M.; Timmo, K.; Danilson, M.; Altosaar, M.; Grossberg, M.; Ernits, K.

    2015-12-01

    In this work we studied the influence of oxidative etching of CZTS monograin surface to the performance of CZTS monograin layer solar cells. The chemistry of CZTS monograin powder surfaces submitted to bromine in methanol and KCN aqueous solutions was investigated by X-ray photoelectron spectroscopy. After bromine etching, elemental sulfur, Sn-O and/or Sn-Br species are formed on the CZTS crystal surface. Sulfur is completely removed by subsequent KCN etching, but oxides and bromides remained on the surface until CdS deposition. These species dissolve in alkaline solution and influence properties of CdS. The conversion efficiency of solar cells improved after the chemical etching prior to CdS deposition and the effect can be attributed to the change of the absorber material crystals surface composition and properties suitable for the effective p-n junction formation. The best CZTS monograin layer solar cell showed conversation efficiency of 7.04% (active area 9.38%).

  3. Some characteristics of solar cells with vertical p-n junction on the base of Ga In P As/In P graded-gap heterostructure

    International Nuclear Information System (INIS)

    The article studies electric and spectrum characteristics and performance of solar cell battery with vertical p-n junction on the base of Ga In P As/In P graded-gap heterostructure grown by liquid epitaxy. The performance of solar cell battery contained 3 diodes assembled in a single model u is amounted to∼3.5% under centuple concentration of solar radiation

  4. Restoration of Functional Gap Junctions through Internal Ribosome Entry Site-Dependent Synthesis of Endogenous Connexins in Density-Inhibited Cancer Cells

    OpenAIRE

    Lahlou, Hicham; Fanjul, Marjorie; Pradayrol, Lucien; Susini, Christiane; Pyronnet, Stéphane

    2005-01-01

    Gap junctions are composed of connexins and are critical for the maintenance of the differentiated state. Consistently, connexin expression is impaired in most cancer cells, and forced expression of connexins following cDNA transfection reverses the tumor phenotype. We have found that the restoration of density inhibition of human pancreatic cancer cells by the antiproliferative somatostatin receptor 2 (sst2) is due to overexpression of endogenous connexins Cx26 and Cx43 and consequent format...

  5. Co-culture of neural crest stem cells (NCSC and insulin producing beta-TC6 cells results in cadherin junctions and protection against cytokine-induced beta-cell death.

    Directory of Open Access Journals (Sweden)

    Anongnad Ngamjariyawat

    Full Text Available PURPOSE: Transplantation of pancreatic islets to Type 1 diabetes patients is hampered by inflammatory reactions at the transplantation site leading to dysfunction and death of insulin producing beta-cells. Recently we have shown that co-transplantation of neural crest stem cells (NCSCs together with the islet cells improves transplantation outcome. The aim of the present investigation was to describe in vitro interactions between NCSCs and insulin producing beta-TC6 cells that may mediate protection against cytokine-induced beta-cell death. PROCEDURES: Beta-TC6 and NCSC cells were cultured either alone or together, and either with or without cell culture inserts. The cultures were then exposed to the pro-inflammatory cytokines IL-1β and IFN-γ for 48 hours followed by analysis of cell death rates (flow cytometry, nitrite production (Griess reagent, protein localization (immunofluorescence and protein phosphorylation (flow cytometry. RESULTS: We observed that beta-TC6 cells co-cultured with NCSCs were protected against cytokine-induced cell death, but not when separated by cell culture inserts. This occurred in parallel with (i augmented production of nitrite from beta-TC6 cells, indicating that increased cell survival allows a sustained production of nitric oxide; (ii NCSC-derived laminin production; (iii decreased phospho-FAK staining in beta-TC6 cell focal adhesions, and (iv decreased beta-TC6 cell phosphorylation of ERK(T202/Y204, FAK(Y397 and FAK(Y576. Furthermore, co-culture also resulted in cadherin and beta-catenin accumulations at the NCSC/beta-TC6 cell junctions. Finally, the gap junction inhibitor carbenoxolone did not affect cytokine-induced beta-cell death during co-culture with NCSCs. CONCLUSION: In summary, direct contacts, but not soluble factors, promote improved beta-TC6 viability when co-cultured with NCSCs. We hypothesize that cadherin junctions between NCSC and beta-TC6 cells promote powerful signals that maintain beta-cell

  6. Enhancing performance of amorphous SiGe single junction solar cells by post-deposition thermal annealing

    International Nuclear Information System (INIS)

    In this work, amorphous silicon-germanium (a-SiGe:H) p-i-n single junction solar cells are fabricated using a 40 MHz plasma-enhanced chemical vapor deposition system. Their s-curve characteristics were observed by current density-voltage measurements. Thermal annealing of cells at 150 °C in a vacuum effectively overcame the s-curve behavior. Additionally, comparing the external quantum efficiency spectra of annealed samples with those of as-deposited samples revealed that the spectral response of annealed cells was higher in the long wavelength range (600 ∼ 900 nm). Raman spectroscopy and electrical conductivity analyses revealed that the n-type microcrystalline silicon (n-μc-Si:H) layers of as-deposited cells were not optimal. Experimental results indicate that the i/n barrier heights of the as-deposited and annealed samples were 0.31 eV and 0.20 eV , respectively. The high energy barrier implies that the bad collection ability of charge carriers near the i/n interfaces of solar cells. An energy conversion efficiency of 6.38% was achieved after post-deposition annealing. The improvement in efficiency is concluded to have been caused largely by retention of n-μc-Si:H layers of high crystallinity and electrical conductivity after annealing. - Highlights: ► Demonstration of thermal annealing in overcoming the s-curve behavior. ► Annealing treatments lead to better n-type microcrystalline silicon thin films. ► Energy conversion efficiency of 6.38% was achieved after post-deposition annealing

  7. Optimization of amorphous silicon double junction solar cells for an efficient photoelectrochemical water splitting device based on a bismuth vanadate photoanode.

    Science.gov (United States)

    Han, Lihao; Abdi, Fatwa F; Perez Rodriguez, Paula; Dam, Bernard; van de Krol, Roel; Zeman, Miro; Smets, Arno H M

    2014-03-01

    A photoelectrochemical water splitting device (PEC-WSD) was designed and fabricated based on cobalt-phosphate-catalysed and tungsten-gradient-doped bismuth vanadate (W:BiVO4) as the photoanode. A simple and cheap hydrogenated amorphous silicon (a-Si:H) double junction solar cell has been used to provide additional bias. The advantage of using thin film silicon (TF-Si) based solar cells is that this photovoltaic (PV) technology meets the crucial requirements for the PV component in PEC-WSDs based on W:BiVO4 photoanodes. TF-Si PV devices are stable in aqueous solutions, are manufactured by simple and cheap fabrication processes and their spectral response, voltage and current density show an excellent match with the photoanode. This paper is mainly focused on the optimization of the TF-Si solar cell with respect to the remaining solar spectrum transmitted through the W:BiVO4 photoanode. The current matching between the top and bottom cells is studied and optimized by varying the thickness of the a-Si:H top cell. We support the experimental optimization of the current balance between the two sub-cells with simulations of the PV devices. In addition, the impact of the light induced degradation of the a-Si:H double junction, the so-called Staebler-Wronski Effect (SWE), on the performance of the PEC-WSD has been studied. The light soaking experiments on the a-Si:H/a-Si:H double junctions over 1000 hours show that the efficiency of a stand-alone a-Si:H/a-Si:H double junction cell is significantly reduced due to the SWE. Nevertheless, the SWE has a significantly smaller effect on the performance of the PEC-WSD. PMID:24452785

  8. Prolactin and glucocorticoid signaling induces lactation-specific tight junctions concurrent with β-casein expression in mammary epithelial cells.

    Science.gov (United States)

    Kobayashi, Ken; Tsugami, Yusaku; Matsunaga, Kota; Oyama, Shoko; Kuki, Chinatsu; Kumura, Haruto

    2016-08-01

    Alveolar mammary epithelial cells (MECs) in mammary glands are highly specialized cells that produce milk for suckling infants. Alveolar MECs also form less permeable tight junctions (TJs) to prevent the leakage of milk components after parturition. In the formation process of less permeable TJs, MECs show a selective downregulation of Cldn4 and a localization change of Cldn3. To investigate what induces less permeable TJs through these compositional changes in Cldns, we focused on two lactogenesis-related hormones: prolactin (Prl) and glucocorticoids. Prl caused a downregulation of Cldn3 and Cldn4 with the formation of leaky TJs in MECs in vitro. Prl-treated MECs also showed low β-casein expression with the activation of STAT5 signaling. By contrast, dexamethasone (Dex), a glucocorticoid analogue, upregulated Cldn3 and Cldn4, concurrent with the formation of less permeable TJs and the activation of glucocorticoid signaling without the expression of β-casein. Cotreatment with Prl and Dex induced the selective downregulation of Cldn4 and the concentration of Cldn3 in the region of TJs concurrent with less permeable TJ formation and high β-casein expression. The inhibition of Prl secretion by bromocriptine in lactating mice induced the upregulation of Cldn3 and Cldn4 concurrent with the downregulation of milk production. These results indicate that the coactivation of Prl and glucocorticoid signaling induces lactation-specific less permeable TJs concurrent with lactogenesis. PMID:27130254

  9. Work plan for phase 1A paleochannel studies at the Cheney disposal cell, Grand Junction, Colorado: Draft

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    This document will serve as a Work Plan for continuing paleochannel characterization activities at the Cheney disposal site near Grand Junction, Colorado. Elevated levels of nitrate were encountered in ground water from two monitor wells installed in alluvial paleochannels near the Cheney disposal cell in 1994. This triggered a series of investigations (Phase 1) designed to determine the source of nitrate and other chemical constituents in ground water at the site. A comprehensive summary of the Phase 1 field investigations (limited to passive monitoring and modeling studies) conducted by the Remedial Action Contractor (RAC) and Technical Assistance Contractor (TAC) to date is provided in Section 2.0 of this document. Results of Phase 1 were inconclusive regarding the potential interaction between the disposal cell and the paleochannels, so additional Phase 1A investigations are planned. Recommendations for Phase 1A tasks and possible future activities are discussed in Section 3.0. Detailed information on the implementation of the proposed Phase 1A tasks appears in Section 4.0 and will provide the basis for Statements of Work (SOW) for each of these tasks. A detailed sampling plan is provided to ensure quality and a consistency with previous data collection efforts.

  10. The exon junction complex regulates the splicing of cell polarity gene dlg1 to control Wingless signaling in development

    Science.gov (United States)

    Liu, Min; Li, Yajuan; Liu, Aiguo; Li, Ruifeng; Su, Ying; Du, Juan; Li, Cheng; Zhu, Alan Jian

    2016-01-01

    Wingless (Wg)/Wnt signaling is conserved in all metazoan animals and plays critical roles in development. The Wg/Wnt morphogen reception is essential for signal activation, whose activity is mediated through the receptor complex and a scaffold protein Dishevelled (Dsh). We report here that the exon junction complex (EJC) activity is indispensable for Wg signaling by maintaining an appropriate level of Dsh protein for Wg ligand reception in Drosophila. Transcriptome analyses in Drosophila wing imaginal discs indicate that the EJC controls the splicing of the cell polarity gene discs large 1 (dlg1), whose coding protein directly interacts with Dsh. Genetic and biochemical experiments demonstrate that Dlg1 protein acts independently from its role in cell polarity to protect Dsh protein from lysosomal degradation. More importantly, human orthologous Dlg protein is sufficient to promote Dvl protein stabilization and Wnt signaling activity, thus revealing a conserved regulatory mechanism of Wg/Wnt signaling by Dlg and EJC. DOI: http://dx.doi.org/10.7554/eLife.17200.001 PMID:27536874

  11. Work plan for phase 1A paleochannel studies at the Cheney disposal cell, Grand Junction, Colorado: Draft

    International Nuclear Information System (INIS)

    This document will serve as a Work Plan for continuing paleochannel characterization activities at the Cheney disposal site near Grand Junction, Colorado. Elevated levels of nitrate were encountered in ground water from two monitor wells installed in alluvial paleochannels near the Cheney disposal cell in 1994. This triggered a series of investigations (Phase 1) designed to determine the source of nitrate and other chemical constituents in ground water at the site. A comprehensive summary of the Phase 1 field investigations (limited to passive monitoring and modeling studies) conducted by the Remedial Action Contractor (RAC) and Technical Assistance Contractor (TAC) to date is provided in Section 2.0 of this document. Results of Phase 1 were inconclusive regarding the potential interaction between the disposal cell and the paleochannels, so additional Phase 1A investigations are planned. Recommendations for Phase 1A tasks and possible future activities are discussed in Section 3.0. Detailed information on the implementation of the proposed Phase 1A tasks appears in Section 4.0 and will provide the basis for Statements of Work (SOW) for each of these tasks. A detailed sampling plan is provided to ensure quality and a consistency with previous data collection efforts

  12. Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

    Science.gov (United States)

    Kewei, Cao; Tong, Liu; Jingming, Liu; Hui, Xie; Dongyan, Tao; Youwen, Zhao; Zhiyuan, Dong; Feng, Hui

    2016-06-01

    Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B2O3 encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters. Project supported by the National Natural Science Foundation of China (No. 61474104).

  13. The effect of phytic acid on tight junctions in the human intestinal Caco-2 cell line and its mechanism.

    Science.gov (United States)

    Fu, Qingxue; Wang, Huizhen; Xia, Mengxin; Deng, Bing; Shen, Hongyi; Ji, Guang; Li, Guowen; Xie, Yan

    2015-12-01

    This study investigated the effect of phytic acid (IP6), a potential absorption enhancer of flavonoid components, on tight junction (TJ) integrity in Caco-2 cell monolayers and its possible mechanisms. Transepithelial electrical resistance (TEER) across the monolayers decreased rapidly, and the flux of fluorescein sodium (a paracellular marker) increased after treating with IP6 in a concentration-dependent manner. Confocal microscopy results showed that IP6 produced a concentration-dependent attenuation in the distribution of occludin, ZO-1, and claudin-1. Immunoblot analysis revealed that IP6 could down-regulate the expression level of these TJ proteins, which resulted in the opening of TJ. Additionally, the divalent cations Ca(2+) and Mg(2+) influenced the IP6-induced distribution of occludin, ZO-1, and claudin-1 in different directions, which enhanced barrier function. In conclusion, IP6 can decrease the integrity of Caco-2 cell monolayers by modulating the TJ proteins' localization and down-regulating the expression levels of TJ proteins including claudin-1, occludin, and ZO-1; the reduction effects of divalent cations such as Ca(2+) and Mg(2+) on the regulation of TJ induced by IP6 should be addressed. The present work will offer some useful guidance for the application of IP6 in drug delivery area. PMID:26385515

  14. Functional neuromuscular junctions formed by embryonic stem cell-derived motor neurons.

    Directory of Open Access Journals (Sweden)

    Joy A Umbach

    Full Text Available A key objective of stem cell biology is to create physiologically relevant cells suitable for modeling disease pathologies in vitro. Much progress towards this goal has been made in the area of motor neuron (MN disease through the development of methods to direct spinal MN formation from both embryonic and induced pluripotent stem cells. Previous studies have characterized these neurons with respect to their molecular and intrinsic functional properties. However, the synaptic activity of stem cell-derived MNs remains less well defined. In this study, we report the development of low-density co-culture conditions that encourage the formation of active neuromuscular synapses between stem cell-derived MNs and muscle cells in vitro. Fluorescence microscopy reveals the expression of numerous synaptic proteins at these contacts, while dual patch clamp recording detects both spontaneous and multi-quantal evoked synaptic responses similar to those observed in vivo. Together, these findings demonstrate that stem cell-derived MNs innervate muscle cells in a functionally relevant manner. This dual recording approach further offers a sensitive and quantitative assay platform to probe disorders of synaptic dysfunction associated with MN disease.

  15. Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro

    International Nuclear Information System (INIS)

    The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells. (paper)

  16. Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro

    Science.gov (United States)

    Hoentsch, Maxi; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Nebe, J. Barbara

    2012-01-01

    The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells.

  17. Design of InP-based metamorphic high-efficiency five-junction solar cells for concentrated photovoltaics

    International Nuclear Information System (INIS)

    We propose an InP-based upright five-junction (5J) solar cell structure for high conversion efficiency under concentration. In the structure, three bottom subcells are composed of lattice-matched (LM) InGaAsP materials, while two top subcells employ metamorphic InGaP materials. The two InGaP subcells are designed to have the same Ga composition of 30%. The first InGaP subcell is thinned so as to transmit half of the photon flux to the second InGaP subcell, thus forming an upright 5J InGaP(1.64 eV)/InGaP(1.64 eV)/InGaAsP(1.3 eV)/InGaAsP(1.02 eV)/InGaAs(0.74 eV) solar cell structure on the InP substrate. The subcell bandgap energies are chosen in such a way that a current matching condition can be achieved. Because no Al- or N-contained materials are used in the absorbers and only one metamorphic growth is required (with a lattice mismatch of 2.1%), the novel InP-based solar cell architecture is considered practically achievable with current growth technology. By comparing it with a InGaP/GaAs/Ge reference cell and adding additional nonideal factors in the modeling, an efficiency as high as 46.2% is estimated under concentration at ∼1500 suns. (paper)

  18. Heterocellular interaction enhances recruitment of α and β-catenins and ZO-2 into functional gap-junction complexes and induces gap junction-dependant differentiation of mammary epithelial cells

    International Nuclear Information System (INIS)

    Gap junctions (GJ) are required for mammary epithelial differentiation. Using epithelial (SCp2) and myoepithelial-like (SCg6) mouse-derived mammary cells, the role of heterocellular interaction in assembly of GJ complexes and functional differentiation (β-casein expression) was evaluated. Heterocellular interaction is critical for β-casein expression, independent of exogenous basement membrane or cell anchoring substrata. Functional differentiation of SCp2, co-cultured with SCg6, is more sensitive to GJ inhibition relative to homocellular SCp2 cultures differentiated by exogenous basement membrane. Connexin (Cx)32 and Cx43 levels were not regulated across culture conditions; however, GJ functionality was enhanced under differentiation-permissive conditions. Immunoprecipitation studies demonstrated association of junctional complex components (α-catenin, β-catenin and ZO-2) with Cx32 and Cx43, in differentiation conditions, and additionally with Cx30 in heterocellular cultures. Although β-catenin did not shuttle between cadherin and GJ complexes, increased association between connexins and β-catenin in heterocellular cultures was observed. This was concomitant with reduced nuclear β-catenin, suggesting that differentiation in heterocellular cultures involves sequestration of β-catenin in GJ complexes

  19. Basic concepts for the design of high-efficiency single-junction and multibandgap solar cells

    Science.gov (United States)

    Fan, J. C. C.

    1985-01-01

    Concepts for obtaining practical solar-cell modules with one-sun efficiencies up to 30 percent at air mass 1 are now well understood. Such high-efficiency modules utilize multibandgap structures. To achieve module efficiencies significantly above 30 percent, it is necessary to employ different concepts such as spectral compression and broad-band detection. A detailed description of concepts for the design of high-efficiency multibandgap solar cells is given.

  20. Intermolecular recombination assay for mammalian cells that produces recombinants carrying both homologous and nonhomologous junctions.

    OpenAIRE

    Brouillette, S; Chartrand, P

    1987-01-01

    We present an intermolecular recombination assay for mammalian cells that does not involve the reconstitution of a selectable marker. It is based on the generation of a shuttle vector by recombination between a bacterial and a mammalian vector. The recombinants can thus be amplified in mammalian cells, isolated by plasmid rescue in an Escherichia coli RecA- host, and identified by in situ hybridization, by using mammalian vector sequences as probes. Since both parental molecules can share def...

  1. Proteomic and bioinformatic analysis of epithelial tight junction reveals an unexpected cluster of synaptic molecules

    Directory of Open Access Journals (Sweden)

    Tang Vivian W

    2006-12-01

    Full Text Available Abstract Background Zonula occludens, also known as the tight junction, is a specialized cell-cell interaction characterized by membrane "kisses" between epithelial cells. A cytoplasmic plaque of ~100 nm corresponding to a meshwork of densely packed proteins underlies the tight junction membrane domain. Due to its enormous size and difficulties in obtaining a biochemically pure fraction, the molecular composition of the tight junction remains largely unknown. Results A novel biochemical purification protocol has been developed to isolate tight junction protein complexes from cultured human epithelial cells. After identification of proteins by mass spectroscopy and fingerprint analysis, candidate proteins are scored and assessed individually. A simple algorithm has been devised to incorporate transmembrane domains and protein modification sites for scoring membrane proteins. Using this new scoring system, a total of 912 proteins have been identified. These 912 hits are analyzed using a bioinformatics approach to bin the hits in 4 categories: configuration, molecular function, cellular function, and specialized process. Prominent clusters of proteins related to the cytoskeleton, cell adhesion, and vesicular traffic have been identified. Weaker clusters of proteins associated with cell growth, cell migration, translation, and transcription are also found. However, the strongest clusters belong to synaptic proteins and signaling molecules. Localization studies of key components of synaptic transmission have confirmed the presence of both presynaptic and postsynaptic proteins at the tight junction domain. To correlate proteomics data with structure, the tight junction has been examined using electron microscopy. This has revealed many novel structures including end-on cytoskeletal attachments, vesicles fusing/budding at the tight junction membrane domain, secreted substances encased between the tight junction kisses, endocytosis of tight junction

  2. Microtubule plus-end and minus-end capture at adherens junctions is involved in the assembly of apico-basal arrays in polarised epithelial cells.

    Science.gov (United States)

    Bellett, Gemma; Carter, Jane M; Keynton, Jennifer; Goldspink, Deborah; James, Colin; Moss, David K; Mogensen, Mette M

    2009-10-01

    Apico-basal polarisation of epithelial cells involves a dramatic reorganisation of the microtubule cytoskeleton. The classic radial array of microtubules focused on a centrally located centrosome typical of many animal cells is lost or greatly reduced and a non-centrosomal apico-basal array develops. The molecules and mechanisms responsible for the assembly and positioning of these non-centrosomal microtubules have not been fully elucidated. Using a Nocodazole induced regrowth assay in invitro culture (MDCK) and in situ epithelial (cochlear Kolliker's) cell models we establish that the apico-basal array originates from the centrosome and that the non-centrosomal microtubule minus-end anchoring sites do not contribute significantly to their nucleation. Confocal and electron microscopy revealed that an extended radial array assembles with microtubule plus-ends targeting cadheren sites at adherens junctions and EB1 and CLIP-170 co-localising with beta-catenin and dynein clusters at the junction sites. The extended radial array is likely to be a vital intermediate step in the assembly process with cortical anchored dynein providing the mechanical force required for microtubule release, translocation and capture. Ultrastructural analyses of the apico-basal arrays in fully polarised MDCK and Kolliker's cells revealed microtubule minus-end association with the most apical adherens junction (Zonula adherens). We propose that a release and capture model involving both microtubule plus- and minus-end capture at adherens junctions is responsible for the generation of non-centrosomal apico-basal arrays in most centrosome containing polarised epithelial cells. PMID:19479825

  3. Glucocorticoids induce transactivation of tight junction genes occludin and claudin-5 in retinal endothelial cells via a novel cis-element.

    Science.gov (United States)

    Felinski, Edward A; Cox, Amy E; Phillips, Brett E; Antonetti, David A

    2008-06-01

    Tight junctions between vascular endothelial cells help to create the blood-brain and blood-retinal barriers. Breakdown of the retinal tight junction complex is problematic in several disease states including diabetic retinopathy. Glucocorticoids can restore and/or preserve the endothelial barrier to paracellular permeability, although the mechanism remains unclear. We show that glucocorticoid treatment of primary retinal endothelial cells increases content of the tight junction proteins occludin and claudin-5, co-incident with an increase in barrier properties of endothelial monolayers. The glucocorticoid receptor antagonist RU486 reverses both the glucocorticoid-stimulated increase in occludin content and the increase in barrier properties. Transcriptional activity from the human occludin and claudin-5 promoters increases in retinal endothelial cells upon glucocorticoid treatment, and is dependent on the glucocorticoid receptor (GR) as demonstrated by siRNA. Deletion analysis of the occludin promoter reveals a 205bp sequence responsible for the glucocorticoid response. However, this region does not possess a canonical glucocorticoid response element and does not bind to the GR in a chromatin immunoprecipitation (ChIP) assay. Mutational analysis of this region revealed a novel 40bp occludin enhancer element (OEE), containing two highly conserved regions of 10 and 13 base pairs, that is both necessary and sufficient for glucocorticoid-induced gene expression in retinal endothelial cells. These data suggest a novel mechanism for glucocorticoid induction of vascular endothelial barrier properties through increased occludin and claudin-5 gene expression. PMID:18501346

  4. Broadband and omnidirectional anti-reflection layer for III/V multi-junction solar cells

    CERN Document Server

    Diedenhofen, Silke L; Haverkamp, Erik; Bauhuis, Gerard; Schermer, John; Rivas, Jaime Gómez; 10.1016/j.solmat.2012.02.022

    2012-01-01

    We report a novel graded refractive index antireflection coating for III/V quadruple solar cells based on bottom-up grown tapered GaP nanowires. We have calculated the photocurrent density of an InGaP-GaAs-InGaAsP-InGaAs solar cell with a MgF2/ZnS double layer antireflection coating and with a graded refractive index coating. The photocurrent density can be increased by 5.9 % when the solar cell is coated with a graded refractive index layer with a thickness of 1\\mu m. We propose to realize such a graded refractive index layer by growing tapered GaP nanowires on III/V solar cells. For a first demonstration of the feasibility of the growth of tapered nanowires on III/V solar cells, we have grown tapered GaP nanowires on AlInP/GaAs substrates. We show experimentally that the reflection from the nanowire coated substrate is reduced and that the transmission into the substrate is increased for a broad spectral and angular range.

  5. Post-Irradiated Human Submandibular Glands Display High Collagen Deposition, Disorganized Cell Junctions, and an Increased Number of Adipocytes.

    Science.gov (United States)

    Nam, Kihoon; Maruyama, Christina L; Trump, Bryan G; Buchmann, Luke; Hunt, Jason P; Monroe, Marcus M; Baker, Olga J

    2016-06-01

    Salivary glands are vital for maintaining oral health. Head and neck radiation therapy is one of the most common causes of salivary gland hypofunction. Little is known about the structural changes that occur in salivary glands after radiation therapy. The aim of this study is to understand the structural changes that occur in post-irradiated human (submandibular gland [SMG]) as compared with untreated ones. We determined changes in epithelial polarity, presence of collagen deposition, and alteration in adipose tissue. We used formalin-fixed paraffin-embedded human SMG from two female subjects exposed to head and neck irradiation. We utilized hematoxylin and eosin staining and Masson's Trichrome staining. The immunostained tissue sections were examined using confocal microscopy. The number and size of adipocytes per tissue section were calculated using ImageJ, Prism, and SPSS software. Post-irradiated human SMG displayed high collagen deposition, disorganized cell junctions, and an increased number of adipocytes as compared with non-irradiated controls. These findings are important to improve our understanding of the individual risk and variation in radiation-related salivary gland dysfunction. PMID:27126825

  6. Growth and Strain Evaluation of InGaP/InGaAs/Ge Triple-Junction Solar Cell Structures

    Science.gov (United States)

    Alhomoudi, Ibrahim A.

    2016-06-01

    Metalorganic chemical vapor deposition (MOCVD) has been used for development of photovoltaic (PV) structures that enable enhanced efficiency for triple-junction solar cell (TJSC) devices. The in-plane strain, lattice match, surface defects, surface morphology, compositional uniformity, threading dislocations (TDs), and depth profile of each layer of the TJSC structure have been examined. The heteroepitaxial layers were found to be near lattice matched to the substrate with excellent coherence between the layers. The analysis explained that the indium gallium phosphide (InGaP) and indium gallium arsenide (InGaAs) layers on germanium (Ge) substrate are a strained structure with purely tetragonal crystalline phase, which indicates that the TJSC structural layers could maintain high crystalline quality. The biaxial in-plane strain in each layer of the TJSC structure is compressive and varies in magnitude for each layer in the structure, being strongly influenced by the Ge substrate and the multiple epilayers of the PV structure. Transmission electron microscopy (TEM) results show no TDs observed over a region with area of 500 nm2, with surface defect density less than 1 × 108 cm-2. No evidence of stacking faults and no visible defects of antiphase domains (APDs) at interfaces were observed, indicating adequate nucleation of epitaxial layers on the substrate and on subsequent growth layers. Furthermore, secondary-ion mass spectrometry (SIMS) analysis showed no significant Ge diffusion from the substrate into the TJSC structure.

  7. Conversion efficiency limits and bandgap designs for multi-junction solar cells with internal radiative efficiencies below unity.

    Science.gov (United States)

    Zhu, Lin; Mochizuki, Toshimitsu; Yoshita, Masahiro; Chen, Shaoqiang; Kim, Changsu; Akiyama, Hidefumi; Kanemitsu, Yoshihiko

    2016-05-16

    We calculated the conversion-efficiency limit ηsc and the optimized subcell bandgap energies of 1 to 5 junction solar cells without and with intermediate reflectors under 1-sun AM1.5G and 1000-sun AM1.5D irradiations, particularly including the impact of internal radiative efficiency (ηint) below unity for realistic subcell materials on the basis of an extended detailed-balance theory. We found that the conversion-efficiency limit ηsc significantly drops when the geometric mean ηint* of all subcell ηint in the stack reduces from 1 to 0.1, and that ηsc degrades linearly to logηint* for ηint* below 0.1. For ηint*<0.1 differences in ηsc due to additional intermediate reflectors became very small if all subcells are optically thick for sun light. We obtained characteristic optimized bandgap energies, which reflect both ηint* decrease and AM1.5 spectral gaps. These results provide realistic efficiency targets and design principles. PMID:27409948

  8. Gamma-ray irradiation hardness of arrayed silicon microhole-based radial p–n junction solar cells

    International Nuclear Information System (INIS)

    The γ-ray irradiation hardness of arrayed silicon microhole-based radial p–n junction (ASMRJ) solar cells (SCs) has been experimentally studied. It was found that the sidewall morphology of the microhole arrays had an important effect on the radiation hardness, so the 4 µm-pitch ASMRJ SCs with hole arrays' sidewalls both unpassivated and passivated were made and referred to as 4 µm-U-ASMRJ and -P-ASMRJ SCs, respectively. On increasing the radiation doses, in contrast with the monotonous and rapid degradation of short circuit current density and open circuit voltage for the planar SCs, these parameters for the 4 µm-U-ASMRJ SCs show a small increase in the initial stage of γ-ray irradiation and then a slow decline. Average conversion efficiency shows an initial slight ascent by 4.5%. Additionally, the average conversion efficiency for the 2 µm-U-ASMRJ SCs shows an initial slight ascent by 5.7%. When the radiation doses grow to 8 × 106 rad, the average conversion efficiency degradation rates for the 2 µm- and 4 µm-U-ASMRJ SCs are 14% and 15%, respectively, whereas it is 39% for the planar SCs. The radiation-gettering mechanism is suggested to explain the radiation-hardened properties of the U-ASMRJ SCs. (paper)

  9. The effects of anthracene and methylated anthracenes on gap junctional intercellular communication in rat liver epithelial cells.

    Science.gov (United States)

    Upham, B L; Weis, L M; Rummel, A M; Masten, S J; Trosko, J E

    1996-12-01

    Polycyclic aromatic hydrocarbons (PAHs), many of which are known carcinogens, are derived from the pyrolysis of organic materials. A rich source of PAHs is cigarette smoke, which contains methylated anthracenes and phenanthrenes as the predominant PAHs. The tumor-promoting activity of cigarette smoke has been well documented. The down-regulation of gap junction intercellular communication (GJIC) by nongenotoxic chemicals and several oncogenes has been implicated in tumor promotion. Therefore, we determined the effects of the three isomers of methylanthracene on GJIC in WB-F344 rat liver epithelial cells. Anthracene and 2-methylanthracene did not significantly inhibit GJIC, whereas anthracene methylated in the 1 or 9 position reversibly inhibited GJIC with I50 values of 22 and 36 microM, respectively. Inhibition occurred within 15 min. In conclusion, the biological effect of methylanthracene depends on the ring position of the methyl group, and these inhibitory isomers could play a potential role in tumor promotion of methylated PAH-rich mixtures such as cigarette smoke and crude oil products. PMID:8954755

  10. Two-pulse space-time photocurrent correlations at graphene p-n junctions reveal hot carrier cooling dynamics near the Fermi level

    Directory of Open Access Journals (Sweden)

    McEuen P.L.

    2013-03-01

    Full Text Available Two-pulse excitation at a graphene p-n junction generates a time-dependent photocurrent response that we show functions as a novel ultrafast thermometer of the hot electron temperature, Te(t. The extracted hot electron cooling rates are consistent with heat dissipation near the Fermi level of graphene occurring by an acoustic phonon supercollision mechanism.

  11. Cell junction-associated proteins IQGAP1, MAGI-2, CASK, spectrins, and α-actinin are components of the nephrin multiprotein complex

    OpenAIRE

    Lehtonen, Sanna; Ryan, Jennifer J; Kudlicka, Krystyna; Iino, Noriaki; Zhou, Huilin; Farquhar, Marilyn G.

    2005-01-01

    Nephrin is a cell surface receptor of the Ig superfamily that localizes to slit diaphragms, the specialized junctions between the interdigitating foot processes of the glomerular epithelium (podocytes) in the kidney. Mutations in the NPHS1 gene encoding nephrin lead to proteinuria and congenital nephrotic syndrome, indicating that nephrin is essential for normal glomerular development and function. To identify nephrin-binding proteins, we performed mass spectrometry on proteins obtained from ...

  12. GaInP/GaAs tandem solar cells with highly Te- and Mg-doped GaAs tunnel junctions grown by MBE

    Science.gov (United States)

    Zheng, Xin-He; Liu, San-Jie; Xia, Yu; Gan, Xing-Yuan; Wang, Hai-Xiao; Wang, Nai-Ming; Yang, Hui

    2015-10-01

    We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction (TJ) with using tellurium (Te) and magnesium (Mg) as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy (MBE) at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 mA/cm2, but a low open-circuit voltage range of 1.4 V˜1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy (SIMS) analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended GaAs n++/p++ junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ˜ 2.5 × 1020 in GaAs could cause a lattice strain of 10-3 in magnitude and thus a surface roughening, which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell. Project supported by the SINANO-SONY Joint Program (Grant No. Y1AAQ11001), the National Natural Science Foundation of China (Grant No. 61274134), the USCB Start-up Program (Grant No. 06105033), and the International Cooperation Projects of Suzhou City, China (Grant No. SH201215).

  13. GaInP/GaAs tandem solar cells with highly Te-and Mg-doped GaAs tunnel junctions grown by MBE

    Institute of Scientific and Technical Information of China (English)

    郑新和; 刘三姐; 夏宇; 甘兴源; 王海啸; 王乃明; 杨辉

    2015-01-01

    We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction (TJ) with using tellurium (Te) and magnesium (Mg) as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy (MBE) at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 mA/cm2, but a low open-circuit voltage range of 1.4 V∼1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy (SIMS) analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended GaAs n++/p++junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of∼2.5 × 1020 in GaAs could cause a lattice strain of 10−3 in magnitude and thus a surface roughening, which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell.

  14. Characteristics of liver cancer stem cells and clinical correlations.

    Science.gov (United States)

    Cheng, Zhuo; Li, Xiaofeng; Ding, Jin

    2016-09-01

    Liver cancer is an aggressive malignant disease with a poor prognosis. Patients with liver cancer are usually diagnosed at an advanced stage and thus miss the opportunity for surgical resection. Chemotherapy and radiofrequency ablation, which target tumor bulk, have exhibited limited therapeutic efficacy to date. Liver cancer stem cells (CSCs) are a small subset of undifferentiated cells existed in liver cancer, which are considered to be responsible for liver cancer initiation, metastasis, relapse and chemoresistance. Elucidating liver CSC characteristics and disclosing their regulatory mechanism might not only deepen our understanding of the pathogenesis of liver cancer but also facilitate the development of diagnostic, prognostic and therapeutic approaches to improve the clinical management of liver cancer. In this review, we will summarize the recent advances in liver CSC research in terms of the origin, identification, regulation and clinical correlation. PMID:26272183

  15. Towards 12% stabilised efficiency in single junction polymorphous silicon solar cells: experimental developments and model predictions

    Science.gov (United States)

    Abolmasov, Sergey; Cabarrocas, Pere Roca i.; Chatterjee, Parsathi

    2016-01-01

    We have combined recent experimental developments in our laboratory with modelling to devise ways of maximising the stabilised efficiency of hydrogenated amorphous silicon (a-Si:H) PIN solar cells. The cells were fabricated using the conventional plasma enhanced chemical vapour deposition (PECVD) technique at various temperatures, pressures and gas flow ratios. A detailed electrical-optical simulator was used to examine the effect of using wide band gap P-and N-doped μc-SiOx:H layers, as well as a MgF2 anti-reflection coating (ARC) on cell performance. We find that with the best quality a-Si:H so far produced in our laboratory and optimised deposition parameters for the corresponding solar cell, we could not attain a 10% stabilised efficiency due to the high stabilised defect density of a-Si:H, although this landmark has been achieved in some laboratories. On the other hand, a close cousin of a-Si:H, hydrogenated polymorphous silicon (pm-Si:H), a nano-structured silicon thin film produced by PECVD under conditions close to powder formation, has been developed in our laboratory. This material has been shown to have a lower initial and stabilised defect density as well as higher hole mobility than a-Si:H. Modelling indicates that it is possible to attain stabilised efficiencies of 12% when pm-Si:H is incorporated in a solar cell, deposited in a NIP configuration to reduce the P/I interface defects and combined with P- and N-doped μc-SiOx:H layers and a MgF2 ARC.

  16. Towards 12% stabilised efficiency in single junction polymorphous silicon solar cells: experimental developments and model predictions

    Directory of Open Access Journals (Sweden)

    Abolmasov Sergey

    2016-01-01

    Full Text Available We have combined recent experimental developments in our laboratory with modelling to devise ways of maximising the stabilised efficiency of hydrogenated amorphous silicon (a-Si:H PIN solar cells. The cells were fabricated using the conventional plasma enhanced chemical vapour deposition (PECVD technique at various temperatures, pressures and gas flow ratios. A detailed electrical-optical simulator was used to examine the effect of using wide band gap P-and N-doped μc-SiOx:H layers, as well as a MgF2 anti-reflection coating (ARC on cell performance. We find that with the best quality a-Si:H so far produced in our laboratory and optimised deposition parameters for the corresponding solar cell, we could not attain a 10% stabilised efficiency due to the high stabilised defect density of a-Si:H, although this landmark has been achieved in some laboratories. On the other hand, a close cousin of a-Si:H, hydrogenated polymorphous silicon (pm-Si:H, a nano-structured silicon thin film produced by PECVD under conditions close to powder formation, has been developed in our laboratory. This material has been shown to have a lower initial and stabilised defect density as well as higher hole mobility than a-Si:H. Modelling indicates that it is possible to attain stabilised efficiencies of 12% when pm-Si:H is incorporated in a solar cell, deposited in a NIP configuration to reduce the P/I interface defects and combined with P- and N-doped μc-SiOx:H layers and a MgF2 ARC.

  17. Far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under forward DC bias

    Science.gov (United States)

    Wenbo, Xiao; Xingdao, He; Yiqing, Gao; Zhimin, Zhang; Jiangtao, Liu

    2012-06-01

    The far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge solar cell are investigated under forward DC bias at room temperature in dark conditions. An electroluminescence viewgraph shows the clear device structures, and the electroluminescence intensity is shown to increases exponentially with bias voltage and linearly with bias current. The results can be interpreted using an equivalent circuit of a single ideal diode model for triple-junction solar cells. The good fit between the measured and calculated data proves the above conclusions. This work is of guiding significance for current solar cell testing and research.

  18. Far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under forward DC bias

    Institute of Scientific and Technical Information of China (English)

    Xiao Wenbo; He Xingdao; Gao Yiqing; Zhang Zhimin; Liu Jiangtao

    2012-01-01

    The far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge solar cell are investigated under forward DC bias at room temperature in dark conditions.An electroluminescence viewgraph shows the clear device structures,and the electroluminescence intensity is shown to increases exponentially with bias voltage and linearly with bias current.The results can be interpreted using an equivalent circuit of a single ideal diode model for triple-junction solar cells.The good fit between the measured and calculated data proves the above conclusions.This work is of guiding significance for current solar cell testing and research.

  19. Double junction photoelectrochemical solar cells based on Cu2ZnSnS4/Cu2ZnSnSe4 thin film as composite photocathode

    Science.gov (United States)

    Zhu, L.; Qiang, Y. H.; Zhao, Y. L.; Gu, X. Q.

    2014-02-01

    A solvothermal method was used to synthesize Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanoparticles. CZTS/CZTSe bilayer films have been fabricated via a layer-by-layer blade coating process on the fluorine dope tin oxide (FTO) substrates. We converted conventional dye-sensitized solar cells (DSSCs) into double junction photoelectrochemical solar cells with the replacement of the Pt-coated counter electrode with the as-prepared films as composite photocathodes. Compared with conventional DSSCs, the cells show an increased short circuit current and power conversion efficiency.

  20. Far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under forward DC bias

    International Nuclear Information System (INIS)

    The far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge solar cell are investigated under forward DC bias at room temperature in dark conditions. An electroluminescence viewgraph shows the clear device structures, and the electroluminescence intensity is shown to increases exponentially with bias voltage and linearly with bias current. The results can be interpreted using an equivalent circuit of a single ideal diode model for triple-junction solar cells. The good fit between the measured and calculated data proves the above conclusions. This work is of guiding significance for current solar cell testing and research. (semiconductor devices)

  1. Cataract-Causing Mutation of Human Connexin 46 Impairs Gap Junction, but Increases Hemichannel Function and Cell Death

    OpenAIRE

    Ren, Qian; Riquelme, Manuel A.; Xu, Ji; Yan, Xiang; Nicholson, Bruce J; Gu, Sumin; Jiang, Jean X.

    2013-01-01

    Connexin channels play a critical role in maintaining metabolic homeostasis and transparency of the lens. Mutations in connexin genes are linked to congenital cataracts in humans. The G143R missense mutation on connexin (Cx) 46 was recently reported to be associated with congenital Coppock cataracts. Here, we showed that the G143R mutation decreased Cx46 gap junctional coupling in a dominant negative manner; however, it significantly increased gap junctional plaques. The G143R mutant also inc...

  2. Endothelial Cell Permeability and Adherens Junction Disruption Induced by Junín Virus Infection

    OpenAIRE

    Lander, Heather M.; Grant, Ashley M.; Albrecht, Thomas; Hill, Terence; Peters, Clarence J.

    2014-01-01

    Junín virus (JUNV) is endemic to the fertile Pampas of Argentina, maintained in nature by the rodent host Calomys musculinus, and the causative agent of Argentine hemorrhagic fever (AHF), which is characterized by vascular dysfunction and fluid distribution abnormalities. Clinical as well as experimental studies implicate involvement of the endothelium in the pathogenesis of AHF, although little is known of its role. JUNV has been shown to result in productive infection of endothelial cells (...

  3. AFM measurements of novel solar cells. Studying electronic properties of Si-based radial junctions

    Czech Academy of Sciences Publication Activity Database

    Hývl, Matěj

    -, č. 1 (2014), s. 52-53. ISSN 1439-4243 R&D Projects: GA ČR GA13-25747S; GA ČR GA13-12386S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : AFM measurements * conductive cantilever * electronic properties * nanowires * PF TUNA Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.imaging-git.com/science/scanning-probe-microscopy/afm-measurements-novel-solar-cells

  4. Material and Process Engineering of Printed Semitransparent Organic Solar Cells and Advanced Multi-junction Architectures

    OpenAIRE

    Guo, Fei

    2015-01-01

    Organic solar cells (OSCs) are continuously drawing attention from both the academic and industrial communities due to their potential in providing low-cost solar electricity. The inherent transparency and various colors of the organic semiconductors allow to fabricate semitransparent and colored OSCs, which endow unique applications in various transparent elements, such as glass windows, transparent rooftop or green houses. To make the semitransparent OSC technology industrially viable it is...

  5. gamma-Aminobutyric acid antagonists decrease junctional communication between L-horizontal cells of the retina.

    OpenAIRE

    Piccolino, M; Neyton, J; Witkovsky, P; Gerschenfeld, H M

    1982-01-01

    The antagonists of gamma-aminobutyric acid, bicuculline and picrotoxin, were found to narrow the receptive field profile of the large field horizontal cell (L1HC) in the turtle retina when added to the perfusion medium in micromolar concentrations. The coupling resistance between neighboring L1HCs was increased by bicuculline or picrotoxin. Under control conditions, the dye Lucifer yellow injected into one L1HC diffused into a large number of neighboring L1HCs; bicuculline or picrotoxin great...

  6. Correlations of differentially expressed gap junction connexins Cx26, Cx30, Cx32, Cx43 and Cx46 with breast cancer progression and prognosis.

    Directory of Open Access Journals (Sweden)

    Ivett Teleki

    Full Text Available Connexins and their cell membrane channels contribute to the control of cell proliferation and compartmental functions in breast glands and their deregulation is linked to breast carcinogenesis. Our aim was to correlate connexin expression with tumor progression and prognosis in primary breast cancers.Meta-analysis of connexin isotype expression data of 1809 and 1899 breast cancers from the Affymetrix and Illumina array platforms, respectively, was performed. Expressed connexins were also monitored at the protein level in tissue microarrays of 127 patients equally representing all tumor grades, using immunofluorescence and multilayer, multichannel digital microscopy. Prognostic correlations were plotted in Kaplan-Meier curves and tested using the log-rank test and cox-regression analysis in univariate and multivariate models.The expression of GJA1/Cx43, GJA3/Cx46 and GJB2/Cx26 and, for the first time, GJA6/Cx30 and GJB1/Cx32 was revealed both in normal human mammary glands and breast carcinomas. Within their subfamilies these connexins can form homo- and heterocellular epithelial channels. In cancer, the array datasets cross-validated each other's prognostic results. In line with the significant correlations found at mRNA level, elevated Cx43 protein levels were linked with significantly improved breast cancer outcome, offering Cx43 protein detection as an independent prognostic marker stronger than vascular invasion or necrosis. As a contrary, elevated Cx30 mRNA and protein levels were associated with a reduced disease outcome offering Cx30 protein detection as an independent prognostic marker outperforming mitotic index and necrosis. Elevated versus low Cx43 protein levels allowed the stratification of grade 2 tumors into good and poor relapse free survival subgroups, respectively. Also, elevated versus low Cx30 levels stratified grade 3 patients into poor and good overall survival subgroups, respectively.Differential expression of Cx43 and Cx

  7. Computational analysis of the maximum power point for GaAs sub-cells in InGaP/GaAs/Ge triple-junction space solar cells

    International Nuclear Information System (INIS)

    The radiation resistance in InGaP/GaAs/Ge triple-junction solar cells is limited by that of the middle GaAs sub-cell. In this work, the electrical performance degradation of different GaAs sub-cells under 1 MeV electron irradiation at fluences below 4 × 1015 cm−2 has been analyzed by means of a computer simulation. The numerical simulations have been carried out using the one-dimensional device modeling program PC1D. The effects of the base and emitter carrier concentrations of the p- and n-type GaAs structures on the maximum power point have been researched using a radiative recombination lifetime, a damage constant for the minority carrier lifetime and carrier removal rate models. An analytical model has been proposed, which is useful to either determine the maximum exposure time or select the appropriate device in order to ensure that the electrical parameters of different GaAs sub-cells will have a satisfactory response to radiation since they will be kept above 80% with respect to the non-irradiated values. (paper)

  8. Finite mobility effects on the radiative efficiency limit of pn -junction solar cells

    Science.gov (United States)

    Mattheis, Julian; Werner, Jürgen H.; Rau, Uwe

    2008-02-01

    The maximum power conversion efficiency of a solar cell as defined by the Shockley-Queisser (SQ) radiative recombination limit relies on the assumption that the collection probability for all photogenerated electron/hole pairs is unity. This assumption implies a virtually infinite mobility μn of the photogenerated charge carriers. In order to compute the radiative efficiency limit with finite mobilities, we solve the continuity equation for minority carrier transport including an additional photon recycling term that accounts for emission of photons by radiative recombination and their subsequent reabsorption. This approach quantitatively connects the SQ approach with the classical diode theory. Even when assuming radiative recombination as the only loss mechanism, the maximum efficiency achievable within our model is reduced drastically when μn drops below a critical value. This critical value depends on the absorption coefficient, the doping density of the absorber material, as well as on the thickness and the light trapping scheme of the solar cell. Thus, these material and device parameters gain a fundamental importance as soon as finite carrier mobility is considered. Our theory yields a criterion that has to be fulfilled by any photovoltaic material in order to guarantee charge separation even in an otherwise most ideal case. Exemplary application of our model to three real photovoltaic materials, crystalline silicon (c-Si) , amorphous silicon (a-Si:H) , as well as Cu(In,Ga)Se2 (CIGS), shows that mobilities of c-Si and CIGS are three, respectively, 1 order of magnitude above this critical limit whereas the effective hole mobilities in a-Si:H are scattered around the critical value. A comparison between solar cells and light-emitting diodes with finite mobility and finite nonradiative lifetime reveals that materials for these complementary devices have to fulfill different requirements.

  9. Single and multi-junction thin film silicon solar cells for flexible photovoltaics

    OpenAIRE

    Söderström, Thomas; Ballif, Christophe

    2009-01-01

    This thesis investigates amorphous (a-Si:H) and microcrystalline (µc-Si:H) solar cells deposited by very high frequency plasma enhanced chemical vapor deposition (VHFPECVD) in the substrate (n-i-p) configuration. It focuses on processes that allow the use of non transparent and flexible substrates such as plastic foil with Tg < 180°C like polyethylene-naphtalate (PEN). In the first part of the work, we concentrate on the light trapping properties of a variety of device configurations. One ori...

  10. Single and multi-junction thin film silicon solar cells for flexible photovoltaics

    OpenAIRE

    Söderström, Thomas

    2009-01-01

    This thesis investigates amorphous (a-Si:H) and microcrystalline (μc-Si:H) solar cells deposited by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) in the n-i-p or substrate configuration. It focuses on processes that allow the use of non transparent and flexible substrates such as plastic foil with Tg < 180°C like poly-ethylene-naphtalate (PEN). In the first part of the work, we concentrate on the light trapping properties of a variety of device conf...

  11. Influence of window layer thickness on double layer antirefiection coating for triple junction solar cells*

    Institute of Scientific and Technical Information of China (English)

    Wang Lijuan; Zhan Feng; Yu Ying; Zhu Yan; Liu Shaoqing; Huang Shesong; Ni Haiqiao; Niu Zhichuan

    2011-01-01

    The optimization of a SiO2/TiO2, SiO2/ZnS double layer antireflection coating (ARC) on Ga0.5ln0.5P/ln0.02Ga0.98As/Ge solar cells for terrestrial application is discussed. The Al0.5In0.5P window layer thickness is also taken into consideration. It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer.

  12. Influence of window layer thickness on double layer antireflection coating for triple junction solar cells

    International Nuclear Information System (INIS)

    The optimization of a SiO2/TiO2, SiO2/ZnS double layer antireflection coating (ARC) on Ga0.5In0.5P/In0.02Ga0.98As/Ge solar cells for terrestrial application is discussed. The Al0.5In0.5P window layer thickness is also taken into consideration. It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer. (semiconductor technology)

  13. Poly(3-hexylthiophene) films by electrospray deposition for crystalline silicon/organic hybrid junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hiate, Taiga; Miyauchi, Naoto; Tang, Zeguo; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 858-3676 (Japan)

    2012-10-15

    The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) and conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on P3HT for use in crystalline silicon/organic hybrid heterojunction solar cells on CZ crystalline silicon (c-Si) (100) wafer was investigated using real-time characterization by spectroscopic ellipsometry (SE). In contrast to the nonuniform deposition of products frequently obtained by conventional spin-coating, a uniform deposition of P3HT and PEDOT:PSS films were achieved on flat and textured hydrophobic c-Si(100) wafers by adjusting the deposition conditions. The c-Si/P3HT/PEDOT:PSS heterojunction solar cells exhibited efficiencies of 4.1 and 6.3% on flat and textured c-Si(100) wafers, respectively. These findings suggest that ESD is a promising method for the uniform deposition of P3HT and PEDOT:PSS films on flat and textured hydrophobic substrates. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Gap junction- and hemichannel-independent actions of connexins

    OpenAIRE

    Jiang, Jean X.; Gu, Sumin

    2004-01-01

    Connexins have been known to be the protein building blocks of gap junctions and mediate cell–cell communication. In contrast to the conventional dogma, recent evidence suggests that in addition to forming gap junction channels, connexins possess gap junction-independent functions. One important gap junction-independent function for connexins is to serve as the major functional component for hemichannels, the un-apposed halves of gap junctions. Hemichannels, as independent functional units, p...

  15. Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

    International Nuclear Information System (INIS)

    InAs/GaAs strain-balanced quantum dot (QD) n-i-p solar cells were fabricated by epitaxial lift-off (ELO), creating thin and flexible devices that exhibit an enhanced sub-GaAs bandgap current collection extending into the near infrared. Materials and optical analysis indicates that QD quality after ELO processing is preserved, which is supported by transmission electron microscopy images of the QD superlattice post-ELO. Spectral responsivity measurements depict a broadband resonant cavity enhancement past the GaAs bandedge, which is due to the thinning of the device. Integrated external quantum efficiency shows a QD contribution to the short circuit current density of 0.23 mA/cm2

  16. MIrExpress: A Database for Gene Coexpression Correlation in Immune Cells Based on Mutual Information and Pearson Correlation.

    Science.gov (United States)

    Wang, Luman; Mo, Qiaochu; Wang, Jianxin

    2015-01-01

    Most current gene coexpression databases support the analysis for linear correlation of gene pairs, but not nonlinear correlation of them, which hinders precisely evaluating the gene-gene coexpression strengths. Here, we report a new database, MIrExpress, which takes advantage of the information theory, as well as the Pearson linear correlation method, to measure the linear correlation, nonlinear correlation, and their hybrid of cell-specific gene coexpressions in immune cells. For a given gene pair or probe set pair input by web users, both mutual information (MI) and Pearson correlation coefficient (r) are calculated, and several corresponding values are reported to reflect their coexpression correlation nature, including MI and r values, their respective rank orderings, their rank comparison, and their hybrid correlation value. Furthermore, for a given gene, the top 10 most relevant genes to it are displayed with the MI, r, or their hybrid perspective, respectively. Currently, the database totally includes 16 human cell groups, involving 20,283 human genes. The expression data and the calculated correlation results from the database are interactively accessible on the web page and can be implemented for other related applications and researches. PMID:26881263

  17. Abnormal Activation of RhoA/ROCK-I Signaling in Junctional Zone Smooth Muscle Cells of Patients With Adenomyosis.

    Science.gov (United States)

    Wang, S; Duan, H; Zhang, Y; Sun, F Q

    2016-03-01

    Adenomyosis (ADS) is a common estrogen-dependent gynecological disease with unknown etiology. The RhoA/Rho-kinase (ROCK) signaling pathway is involved in various cellular functions, including migration, proliferation, and smooth muscle contraction. Here we examined the potential role of this pathway in junctional zone (JZ) contraction in women with and without ADS. We demonstrated that in the normal JZ, RhoA and ROCK-I messenger RNA (mRNA) and protein expression was significantly higher in the proliferative phase of the menstrual cycle than in the secretory phase. Expression of RhoA and ROCK-I in the JZ from women with ADS was significantly higher than in the control women and showed no significant differences across the menstrual cycle. Treatment of JZ smooth muscle cells (JZSMCs) with estrogen at 0, 1, 10, or 100 nmol/L for 24 hours resulted in increased expression of RhoA, ROCK-I, and myosin light-chain (MLC) phosphorylation (p-MLC) in a dose-dependent manner. In parallel to its effects on p-MLC, estrogen-mediated, dose-dependent contraction responses in JZSMCs. Estrogen-mediated contraction in the ADS group was significantly higher than in the controls and also showed no significant differences across the menstrual cycle. These effects were suppressed in the presence of ICI 182780 or Y27632, supporting an estrogen receptor-dependent and RhoA activation-dependent mechanism. Our results indicate that the level of RhoA and ROCK-I increases in patients with ADS and the cyclic change is lost. Estrogen may affect uterine JZ contraction of ADS by enhancing RhoA/ ROCK-I signaling. PMID:26335177

  18. Renal transitional cell carcinoma: a sonographic and radiological correlation

    International Nuclear Information System (INIS)

    A sonographic study was performed on nine patients with renal transitional cell carcinoma and the findings correlated with those of excretory urography, retrograde and/or antegrade pyelography. In six patients the correct diagnosis was considered mainly by the radiological features. In the remaining three patients, due to its unusual manifestations, this diagnosis was accomplished only by sonography. A small echogenic mass at the peryphery of a chronic hydronephrotic kidney, a huge complex mass due to a multiple arborescent papilary tumor and a demonstration of a mass in a presumptive renal pelvic inflammatory disease, respectively, represented these uncommon aspects. The spectrum of features of this entity and the related differential diagnosis are also presented. (Author)

  19. Gap Junctions in C. elegans

    Directory of Open Access Journals (Sweden)

    ChristianC.Naus

    2014-02-01

    Full Text Available As in other multicellular organisms, the nematode Caenorhabditis elegans uses gap junctions to provide direct cell-to-cell contact. The nematode gap junctions are formed by innexins (invertebrate analogs of the connexins; a family of proteins that surprisingly share no primary sequence homology, but do share structural and functional similarity with connexins. The model organism C. elegans contains 25 innexin genes and innexins are found in virtually all cell types and tissues. Additionally, many innexins have dynamic expression patterns during development, and several innexins are essential genes in the nematode. C. elegans is a popular invertebrate model due to several features including a simple anatomy, a complete cell lineage, sequenced genome and an array of genetic resources. Thus the worm has potential to offer valuable insights into the various functions of gap junction mediated intercellular communication.

  20. Single-cell protein secretomic signatures as potential correlates to tumor cell lineage evolution and cell-cell interaction

    Directory of Open Access Journals (Sweden)

    Minsuk eKwak

    2013-02-01

    Full Text Available Secreted proteins including cytokines, chemokines and growth factors represent important functional regulators mediating a range of cellular behavior and cell-cell paracrine/autocrine signaling, e.g. in the immunological system, tumor microenvironment or stem cell niche. Detection of these proteins is of great value not only in basic cell biology but also for diagnosis and therapeutic monitoring of human diseases such as cancer. However, due to co-production of multiple effector proteins from a single cell, referred to as polyfunctionality, it is biologically informative to measure a panel of secreted proteins, or secretomic signature, at the level of single cells. Recent evidence further indicates that a genetically-identical cell population can give rise to diverse phenotypic differences. It is known that cytokines, for example, in the immune system define the effector functions and lineage differentiation of immune cells. In this Perspective Article, we hypothesize that protein secretion profile may represent a universal measure to identify the definitive correlate in the larger context of cellular functions to dissect cellular heterogeneity and evolutionary lineage relationship in human cancer.

  1. Aberration-corrected transmission electron microscopy analyses of GaAs/Si interfaces in wafer-bonded multi-junction solar cells

    International Nuclear Information System (INIS)

    Aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) investigations have been applied to investigate the structure and composition fluctuations near interfaces in wafer-bonded multi-junction solar cells. Multi-junction solar cells are of particular interest since efficiencies well above 40% have been obtained for concentrator solar cells which are based on III-V compound semiconductors. In this methodologically oriented investigation, we explore the potential of combining aberration-corrected high-angle annular dark-field STEM imaging (HAADF-STEM) with spectroscopic techniques, such as EELS and energy-dispersive X-ray spectroscopy (EDXS), and with high-resolution transmission electron microscopy (HR-TEM), in order to analyze the effects of fast atom beam (FAB) and ion beam bombardment (IB) activation treatments on the structure and composition of bonding interfaces of wafer-bonded solar cells on Si substrates. Investigations using STEM/EELS are able to measure quantitatively and with high precision the widths and the fluctuations in element distributions within amorphous interface layers of nanometer extensions, including those of light elements. Such measurements allow the control of the activation treatments and thus support assessing electrical conductivity phenomena connected with impurity and dopant distributions near interfaces for optimized performance of the solar cells. - Highlights: • Aberration-corrected TEM and EELS reveal structural and elemental profiles across GaAs/Si bond interfaces in wafer-bonded GaInP/GaAs/Si - multi-junction solar cells. • Fluctuations in elemental concentration in nanometer-thick amorphous interface layers, including the disrubutions of light elements, are measured using EELS. • The projected widths of the interface layers are determined on the atomic scale from STEM-HAADF measurements. • The effects of atom and ion beam activation treatment on the bonding

  2. Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell

    International Nuclear Information System (INIS)

    Highly efficient semiconductor photoelectrodes for solar hydrogen production through photocatalytic water splitting are a promising and challenge solution to solve the energy problems. In this work, Ag/Cu2O/ZnO tandem triple-junction photoelectrode was designed and prepared. An increase of 11 times of photocurrent is achieved in the Ag/Cu2O/ZnO photoelectrode comparing to that of the Cu2O film. The high performance of the Ag/Cu2O/ZnO film is due to the optimized design of the tandem triple-junction structure, where the localized surface Plasmon resonance of Ag and the hetero-junctions efficiently absorb solar energy, produce, and separate electron-hole pairs in the photocathode

  3. Neuronal gap junction coupling is regulated by glutamate and plays critical role in cell death during neuronal injury.

    Science.gov (United States)

    Wang, Yongfu; Song, Ji-Hoon; Denisova, Janna V; Park, Won-Mee; Fontes, Joseph D; Belousov, Andrei B

    2012-01-11

    In the mammalian CNS, excessive release of glutamate and overactivation of glutamate receptors are responsible for the secondary (delayed) neuronal death following neuronal injury, including ischemia, traumatic brain injury (TBI), and epilepsy. The coupling of neurons by gap junctions (electrical synapses) increases during neuronal injury. We report here that the ischemic increase in neuronal gap junction coupling is regulated by glutamate via group II metabotropic glutamate receptors (mGluRs). Specifically, using electrotonic coupling, Western blots, and siRNA in the mouse somatosensory cortex in vivo and in vitro, we demonstrate that activation of group II mGluRs increases background levels of neuronal gap junction coupling and expression of connexin 36 (Cx36) (neuronal gap junction protein), and inactivation of group II mGluRs prevents the ischemia-mediated increases in the coupling and Cx36 expression. We also show that the regulation is via cAMP/PKA (cAMP-dependent protein kinase)-dependent signaling and posttranscriptional control of Cx36 expression and that other glutamate receptors are not involved in these regulatory mechanisms. Furthermore, using the analysis of neuronal death, we show that inactivation of group II mGluRs or genetic elimination of Cx36 both dramatically reduce ischemia-mediated neuronal death in vitro and in vivo. Similar results are obtained using in vitro models of TBI and epilepsy. Our results indicate that neuronal gap junction coupling is a critical component of glutamate-dependent neuronal death. They also suggest that causal link among group II mGluR function, neuronal gap junction coupling, and neuronal death has a universal character and operates in different types of neuronal injuries. PMID:22238107

  4. Genomic Correlates of Immune-Cell Infiltrates in Colorectal Carcinoma

    Science.gov (United States)

    Giannakis, Marios; Mu, Xinmeng Jasmine; Shukla, Sachet A.; Qian, Zhi Rong; Cohen, Ofir; Nishihara, Reiko; Bahl, Samira; Cao, Yin; Amin-Mansour, Ali; Yamauchi, Mai; Sukawa, Yasutaka; Stewart, Chip; Rosenberg, Mara; Mima, Kosuke; Inamura, Kentaro; Nosho, Katsuhiko; Nowak, Jonathan A.; Lawrence, Michael S.; Giovannucci, Edward L.; Chan, Andrew T.; Ng, Kimmie; Meyerhardt, Jeffrey A.; Van Allen, Eliezer M.; Getz, Gad; Gabriel, Stacey B.; Lander, Eric S.; Wu, Catherine J.; Fuchs, Charles S.; Ogino, Shuji; Garraway, Levi A.

    2016-01-01

    Summary Large-scale genomic characterization of tumors from prospective cohort studies may yield new insights into cancer pathogenesis. We performed whole-exome sequencing of 619 incident colorectal cancers (CRCs) and integrated the results with tumor immunity, pathology, and survival data. We identified recurrently mutated genes in CRC, such as BCL9L, RBM10, CTCF, and KLF5, that were not previously appreciated in this disease. Furthermore, we investigated the genomic correlates of immune-cell infiltration and found that higher neoantigen load was positively associated with overall lymphocytic infiltration, tumor-infiltrating lymphocytes (TILs), memory T cells, and CRC-specific survival. The association with TILs was evident even within microsatellite-stable tumors. We also found positive selection of mutations in HLA genes and other components of the antigen-processing machinery in TIL-rich tumors. These results may inform immunotherapeutic approaches in CRC. More generally, this study demonstrates a framework for future integrative molecular epidemiology research in colorectal and other malignancies. PMID:27149842

  5. Genomic Correlates of Immune-Cell Infiltrates in Colorectal Carcinoma

    Directory of Open Access Journals (Sweden)

    Marios Giannakis

    2016-04-01

    Full Text Available Large-scale genomic characterization of tumors from prospective cohort studies may yield new insights into cancer pathogenesis. We performed whole-exome sequencing of 619 incident colorectal cancers (CRCs and integrated the results with tumor immunity, pathology, and survival data. We identified recurrently mutated genes in CRC, such as BCL9L, RBM10, CTCF, and KLF5, that were not previously appreciated in this disease. Furthermore, we investigated the genomic correlates of immune-cell infiltration and found that higher neoantigen load was positively associated with overall lymphocytic infiltration, tumor-infiltrating lymphocytes (TILs, memory T cells, and CRC-specific survival. The association with TILs was evident even within microsatellite-stable tumors. We also found positive selection of mutations in HLA genes and other components of the antigen-processing machinery in TIL-rich tumors. These results may inform immunotherapeutic approaches in CRC. More generally, this study demonstrates a framework for future integrative molecular epidemiology research in colorectal and other malignancies.

  6. The demonstration of a highly efficient SiGe Type-II hetero-junction solar cell with an optimal stress design

    International Nuclear Information System (INIS)

    Highly efficient surface-textured SiGe-based solar cell with top surface trench structure and optimized SiGe/Si type-II hetero-junction design is proposed. The surface-textured structure results in a significant reduction of the surface reflectance from 32% to ∼ 10% in the visible light region with an obvious photonic crystal effect, which can be simulated by finite differential time domain calculations. By varying the top surface trench spacing, broadband antireflection can be realized and total absorption rate greatly enhanced. Moreover, SiGe/Si hetero-structure substrate has also been implemented to enhance the solar cell efficiency by an additional 3% in this work, not only due to the originally higher absorption rate in the SiGe-based material but also due to the enhanced SiGe/Si type-II hetero-structure substrate design. The offset and discontinuousness of the energy band between the Si substrate and the strained Si0.9Ge0.1 type-II hetero-junction structure resulted in higher local electron-hole carrier concentration, which is confined in the Si cap and SiGe quantum well structure, and the longer non-radiative Auger carrier recombination lifetime as measured by femtosecond transient absorption measurements. The integration of these two key technologies-nano-level surface trench structure and optimization of the SiGe/Si type-II hetero-structure, led to highly efficient (∼ 18% for the stable production and 21% for the peak record) nano-surface textured SiGe-based solar cell being achieved and demonstrated in this work. - Highlights: • Highly efficient solar cell. • Surface structure design. • SiGe type II junction

  7. Clathrin and Cx43 gap junction plaque endoexocytosis

    International Nuclear Information System (INIS)

    In earlier transmission electron microscopic studies, we have described pentilaminar gap junctional membrane invaginations and annular gap junction vesicles coated with short, electron-dense bristles. The similarity between these electron-dense bristles and the material surrounding clathrin-coated pits led us to suggest that the dense bristles associated with gap junction structures might be clathrin. To confirm that clathrin is indeed associated with annular gap junction vesicles and gap junction plaques, quantum dot immuno-electron microscopic techniques were used. We report here that clathrin associates with both connexin 43 (Cx43) gap junction plaques and pentilaminar gap junction vesicles. An important finding was the preferential localization of clathrin to the cytoplasmic surface of the annular or of the gap junction plaque membrane of one of the two contacting cells. This is consistent with the possibility that the direction of gap junction plaque internalization into one of two contacting cells is regulated by clathrin

  8. Morphological transformation and effect on gap junction intercellular communication in Syrian hamster embryo cells as screening tests for carcinogens devoid of mutagenic activity.

    Science.gov (United States)

    Rivedal, E; Mikalsen, S O; Sanner, T

    2000-04-01

    A large fraction of chemicals observed to cause cancer in experimental animals is devoid of mutagenic activity. It is therefore of importance to develop methods that can be used to detect and study environmental carcinogenic agents that do not interact directly with DNA. Previous studies have indicated that induction of in vitro cell transformation and inhibition of gap junction intercellular communication are endpoints that could be useful for the detection of non-genotoxic carcinogens. In the present work, 13 compounds [chlordane, Arochlor 1260, di(2-ethylhexyl)phthalate, 1,1,1-trichloro-2, 2-bis(4-chlorophenyl)ethane, limonene, sodium fluoride, ethionine, o-anisidine, benzoyl peroxide, o-vanadate, phenobarbital, 12-O-tetradecanoylphorbol 13-acetate and clofibrate] have been tested for their ability to induce morphological transformation and affect intercellular communication in Syrian hamster embryo cells. The substances were selected on the basis of being proven or suspected non-genotoxic carcinogens, and thus difficult to detect in short-term tests. The data show that nine of the 13 compounds induced morphological transformation, and seven of the 13 inhibited intercellular communication in hamster embryo cells. Taken together, 12 of the 13 substances either induced transformation or caused inhibition of communication. The data suggest that the combined use of morphological transformation and gap junction intercellular communication in Syrian hamster embryo cells may be beneficial when screening for non-genotoxic carcinogens. PMID:10793297

  9. Molecular beam epitaxy of InP single junction and InP/In0.53Ga0.47As monolithically integrated tandem solar cells using solid phosphorous source material

    International Nuclear Information System (INIS)

    This work reports the first InP solar cells, InP/In0.53Ga0.47As tandem solar cells and InP tunnel junctions to be grown using a solid phosphorous source cracker cell in a molecular beam epitaxy system. High p-type doping achieved with this system allowed for the development of InP tunnel junctions. These junctions which allow for improved current matching in subsequent monolithically integrated tandem devices also do not absorb photons which can be utilized in the InGaAs structure. Photocurrent spectral responses compared favorably to devices previously grown in a chemical beam epitaxy system. High resolution x-ray scans demonstrated good lattice matching between constituent parts of the tandem cell. AM0 efficiencies of both InP and InP/InGaAs tandem cells are reported

  10. Adhesion frequency assay for in situ kinetics analysis of cross-junctional molecular interactions at the cell-cell interface.

    Science.gov (United States)

    Zarnitsyna, Veronika I; Zhu, Cheng

    2011-01-01

    The micropipette adhesion assay was developed in 1998 to measure two-dimensional (2D) receptor-ligand binding kinetics. The assay uses a human red blood cell (RBC) as adhesion sensor and presenting cell for one of the interacting molecules. It employs micromanipulation to bring the RBC into contact with another cell that expresses the other interacting molecule with precisely controlled area and time to enable bond formation. The adhesion event is detected as RBC elongation upon pulling the two cells apart. By controlling the density of the ligands immobilized on the RBC surface, the probability of adhesion is kept in mid-range between 0 and 1. The adhesion probability is estimated from the frequency of adhesion events in a sequence of repeated contact cycles between the two cells for a given contact time. Varying the contact time generates a binding curve. Fitting a probabilistic model for receptor-ligand reaction kinetics to the binding curve returns the 2D affinity and off-rate. The assay has been validated using interactions of Fcγ receptors with IgG Fc, selectins with glycoconjugate ligands, integrins with ligands, homotypical cadherin binding, T cell receptor and coreceptor with peptide-major histocompatibility complexes. The method has been used to quantify regulations of 2D kinetics by biophysical factors, such as the membrane microtopology, membrane anchor, molecular orientation and length, carrier stiffness, curvature, and impingement force, as well as biochemical factors, such as modulators of the cytoskeleton and membrane microenvironment where the interacting molecules reside and the surface organization of these molecules. The method has also been used to study the concurrent binding of dual receptor-ligand species, and trimolecular interactions using a modified model. The major advantage of the method is that it allows study of receptors in their native membrane environment. The results could be very different from those obtained using purified

  11. Measurement of the open circuit voltage of individual sub-cells in a dual-junction solar cell

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; Bonnet-Eymard, M.; Bugnon, G.; Cuony, P.; Despeisse, M.; Ballif, C.

    2012-01-01

    Roč. 2, č. 2 (2012), s. 164-168. ISSN 2156-3381 R&D Projects: GA MŠk(CZ) 7E09057 EU Projects: European Commission(XE) 214134 - N2P Institutional research plan: CEZ:AV0Z10100521 Keywords : current-voltage characteristics * photovoltaic cell s * solar energy Subject RIV: BM - Solid Matter Physics ; Magnetism http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6150992

  12. Lymphovascular invasion in testicular germ cell tumors: clinicopathological correlates

    Directory of Open Access Journals (Sweden)

    Yaron Ehrlich

    2013-08-01

    Full Text Available Introduction. We assessed clinical–pathological correlates of lymphovascular invasion in testicular germ–cell tumors.Material and methods. Archived pathology specimens from 145 patients treated by radical orchiectomy for testicular germ cell tumors at our institution in 1995–2006 were reanalyzed by a dedicated urologic pathologist, and the corresponding medical records were reviewed. The association of lymphovascular invasion with clinical and pathological parameters was tested using stepwise logistic regression analysis.Results. Lymphovascular invasion was identified in 38 (26% patients and was associated with younger age, testicular pain at presentation, elevated serum tumor markers, nonseminoma histology, and advanced clinical stage. Orchalgia was indicated as the impetus for referral in 67 (46% patients and characterized as a dull aching sensation, persistent or intermittent in nature. Among the 98 men diagnosed with clinical stage I, those presenting with testicular pain had a 1.8X–higher likelihood of lymphovascular invasion than those without pain (95% CI 1.13–14.9, p = 0.02, and patients with elevated serum tumor markers had an 8.5–fold increased probability of lymphovascular invasion than those presenting with normal tumor markers (CI 1.1–54.2, p = 0.05. Among men with nonseminoma histology, elevated tumor markers was the strongest predictor of lymphovascular invasion in both univariate and multivariate analyses (OR 5.05, 95% CI 1.16–21.8, p = 0.03.Conclusion. Providing pathologists with information on pre–orchiectomy tumor marker levels and, possibly, testicular pain at presentation may increase their vigilance in searching for lymphovascular invasion, potentially improving their diagnostic accuracy. Whether it may also translate into improved oncological outcomes needs further evaluation.

  13. A 3D model for thickness and diffusion capacitance of emitter-base junction determination in a bifacial polycrystalline solar cell under real operating condition

    OpenAIRE

    MBODJI, Senghane; MBOW, Babacar; SISSOKO, Fabe Idrissa BARRO and Grégoire

    2011-01-01

    This paper aims at presenting the behaviour of the space charge region for an n+-p-p+ bifacial solar cell under monochromatic illumination. It also deals with mathematical relations in the describing and the use of new approach that involves both junction and back surface recombination velocities with a 3D modelling study. Based on the normalized carriers' density, versus base depth, the space-charge layer thickness (Z0,u) is studied for various parameters such as grain size g, g...

  14. Analysis of vertebrate gap junction protein.

    OpenAIRE

    Finbow, M E; Shuttleworth, J.; Hamilton, A.E.; Pitts, J D

    1983-01-01

    A new method for the purification of gap junctions is described which depends on the extraction of cell monolayers or tissue homogenates with Triton X-100. The major band on SDS-polyacrylamide gel electrophoresis (PAGE) of junctional preparations from a variety of vertebrate sources has an apparent mol. wt. of 16,000 (16 K). Further evidence for the junctional origin of the 16 K protein is provided by the results of four different experimental approaches. (i) The junctions form a sharp band i...

  15. The distance temperature map as method to analyze the optical properties of Fresnel lenses and their interaction with multi-junction solar cells

    Science.gov (United States)

    Hornung, Thorsten; Kiefel, Peter; Nitz, Peter

    2015-09-01

    The optical efficiency of Fresnel lens based solar concentrators varies with the temperature of the Fresnel lens. The dependency of any quantity of interest (e.g. optical efficiency) on Fresnel lens temperature can be visualized by 2d color plots that simultaneously show it as a function of the distance between solar cell and Fresnel lens and as a function of Fresnel lens temperature. This visualization, which is called DTmap, strongly facilitates the analysis of the thermal behavior of a Fresnel lens and the optimization of module height. Based on DTmaps we reveal and discuss serveral details of the thermal behavior of silicone on glass (SOG) Fresnel lenses. In addition, the DTmap is shown for the efficiency of a system consisting of a Fresnel lens and a lattice matched three-junction and a four-junction solar cell. The results demonstrate that the interaction of the concentrator optics and the solar cell is not trivial and may also be studied using DTmaps.

  16. 3D determination of the minority carrier lifetime and the p-n junction recombination velocity of a polycrystalline silicon solar cell

    International Nuclear Information System (INIS)

    This work presents a theoretical and experimental transient tri-dimensional study conducted for the determination of the bulk component of the minority carrier lifetime and the p-n junction recombination velocity of a bifacial polycrystalline silicon solar cell. The theoretical analysis is based on the columnar model of the grains in the polycrystalline silicon solar cell. The boundaries conditions are defined in order to use Green's function to solve the three-dimensional diffusion equation. This leads to a new expression of the transient photovoltage. The value of the constraint coefficients at interfaces of the grain are computed while those of the effective minority carrier lifetime τeff is extracted from the experimental curve of transient voltage. The bulk lifetime and the p-n junction recombination velocity are deduced and have been compared to those obtained from transient state by one-dimensional modelling of carrier's diffusion. This comparative study permitted us to show grain effects on the lifetime and consequently the inadequacy of one-dimensional modelling of carrier's diffusion in the polycrystalline silicon solar cells.

  17. 3D determination of the minority carrier lifetime and the p-n junction recombination velocity of a polycrystalline silicon solar cell

    Science.gov (United States)

    Sam, R.; Zouma, B.; Zougmoré, F.; Koalaga, Z.; Zoungrana, M.; Zerbo, I.

    2012-02-01

    This work presents a theoretical and experimental transient tri-dimensional study conducted for the determination of the bulk component of the minority carrier lifetime and the p-n junction recombination velocity of a bifacial polycrystalline silicon solar cell. The theoretical analysis is based on the columnar model of the grains in the polycrystalline silicon solar cell. The boundaries conditions are defined in order to use Green's function to solve the three-dimensional diffusion equation. This leads to a new expression of the transient photovoltage. The value of the constraint coefficients at interfaces of the grain are computed while those of the effective minority carrier lifetime τeff is extracted from the experimental curve of transient voltage. The bulk lifetime and the p-n junction recombination velocity are deduced and have been compared to those obtained from transient state by one-dimensional modelling of carrier's diffusion. This comparative study permitted us to show grain effects on the lifetime and consequently the inadequacy of one-dimensional modelling of carrier's diffusion in the polycrystalline silicon solar cells.

  18. The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression.

    Science.gov (United States)

    Fukumura, Kazuhiro; Wakabayashi, Shunichi; Kataoka, Naoyuki; Sakamoto, Hiroshi; Suzuki, Yutaka; Nakai, Kenta; Mayeda, Akila; Inoue, Kunio

    2016-01-01

    The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon-exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT-PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH) to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes. PMID:27490541

  19. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  20. Study on limiting efficiencies of a-Si:H/μc-Si:H-based single-nanowire solar cells under single and tandem junction configurations

    Science.gov (United States)

    Zhai, Xiongfei; Cao, Guoyang; Wu, Shaolong; Shang, Aixue; Li, Xiaofeng

    2015-11-01

    Detailed balance calculations are presented for a-Si:H/μc-Si:H-based single- and tandem-junction single-nanowire solar cells (S- and T-SNSCs). Our study is based on three-dimensional finite-element electromagnetic simulation and thermodynamic balanced analysis, which includes radiative and Auger recombinations simultaneously. We quantify and compare the limiting short-circuit current densities, open-circuit voltages, and light-conversion efficiencies of these highly compact photovoltaic cells, addressing especially the effect of Auger recombination on the open-circuit voltages of SNSCs. Results show that tandem design leads to much higher light-conversion capability than μc-Si:H S-SNSCs, but exhibits superior performance than a-Si:H S-SNSCs only for cells with large radii.

  1. Improvement of the efficiency of triple junction n–i–p solar cells with hot-wire CVD proto- and microcrystalline silicon absorber layers

    OpenAIRE

    Stolk, R.L.; Li, H. B. T.; Franken, R.H.; Schuttauf, J.A.; van der Werf, C.H.M.; J.K. Rath; Schropp, R.E.I.

    2008-01-01

    Hot-wire chemical vapour deposition (HWCVD) was applied for the deposition of intrinsic protocrystalline (proto-Si:H) and microcrystalline silicon (μc-Si:H) absorber layers in thin film solar cells. For a single junction μc-Si:H n–i–p cell on a Ag/ZnO textured back reflector (TBR) with a 2.0 μm i-layer, an 8.5% efficiency was obtained, which showed to be stable after 750 h of light-soaking. The short-circuit current density (Jsc) of this cell was 23.4 mA/cm2, with a high open-circuit voltage ...

  2. Study on limiting efficiencies of a-Si:H/μc-Si:H-based single-nanowire solar cells under single and tandem junction configurations

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Xiongfei; Cao, Guoyang; Wu, Shaolong, E-mail: shaolong-wu@suda.edu.cn, E-mail: xfli@suda.edu.cn; Shang, Aixue; Li, Xiaofeng, E-mail: shaolong-wu@suda.edu.cn, E-mail: xfli@suda.edu.cn [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China)

    2015-11-02

    Detailed balance calculations are presented for a-Si:H/μc-Si:H-based single- and tandem-junction single-nanowire solar cells (S- and T-SNSCs). Our study is based on three-dimensional finite-element electromagnetic simulation and thermodynamic balanced analysis, which includes radiative and Auger recombinations simultaneously. We quantify and compare the limiting short-circuit current densities, open-circuit voltages, and light-conversion efficiencies of these highly compact photovoltaic cells, addressing especially the effect of Auger recombination on the open-circuit voltages of SNSCs. Results show that tandem design leads to much higher light-conversion capability than μc-Si:H S-SNSCs, but exhibits superior performance than a-Si:H S-SNSCs only for cells with large radii.

  3. Growth of ErAs nanodots by molecular beam epitaxy for application to tunneling junctions in multijunction solar cells

    Science.gov (United States)

    Hung, Chao-Yu; Sogabe, Tomah; Miyashita, Naoya; Okada, Yoshitaka

    2016-02-01

    ErAs nanodots (NDs) grown on GaAs(001) substrates by using molecular beam epitaxy (MBE) were investigated. Atomic force microscope images indicate that the size of ErAs NDs increases with deposition time and growth temperature. A calibration was performed to determine the deposition rate of ErAs in order that the size of NDs can be accurately controlled and hence optimized. Local current flow images and surface profiles around ErAs NDs were simultaneously measured to clarify the local conductivity distribution corresponding to a real space profile. Furthermore, we also fabricated and characterized an ErAs-ND-embedded GaAs tunnel junction (TJ), which resulted in a voltage drop of 30 mV for 15 A/cm2 operation current equivalent to 1000 suns concentration, which is less than one-third of that of a conventional heavily doped tunnel junction.

  4. Variable light biasing method to measure component I-V characteristics of multi-junction solar cells

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; Bonnet-Eymard, M.; Boccard, M.; Despeisse, M.; Ballif, C.

    2012-01-01

    Roč. 103, č. 8 (2012), s. 128-133. ISSN 0927-0248 R&D Projects: GA ČR GA202/09/0417 Institutional research plan: CEZ:AV0Z10100521 Keywords : current-voltage characteristics * multi-junction * p-i-n * light bias Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.630, year: 2012 http://www.sciencedirect.com/science/article/pii/S0927024812001705

  5. Boron-doped silicon film as a recombination layer in the tunnel junction of a tandem solar cell

    Institute of Scientific and Technical Information of China (English)

    Shi Mingji; Wang Zhanguo; Liu Shiyong; Peng Wenbo; Xiao Haibo; Zhang Changsha; Zeng Xiangbo

    2009-01-01

    Boron-doped hydrogenated silicon films with different gaseous doping ratios (B2H6/SiH4) were deposited in a plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure of the films was investigated by atomic force microscopy (AFM) and Raman scattering spectroscopy. The electrical properties of the films were characterized by their room temperature electrical conductivity (σ) and the activation energy (Ea). The results show that with an increasing gaseous doping ratio, the silicon films transfer from a microcrystalline to an amorphous phase, and corresponding changes in the electrical properties were observed. The thin boron-doped silicon layers were fabricated as recombination layers in tunnel junctions. The measurements of the Ⅰ-Ⅴ characteristics and the transparency spectra of the junctions indicate that the best gaseous doping ratio of the recombination layer is 0.04, and the film deposited under that condition is amorphous silicon with a small amount of crystallites embedded in it. The junction with such a recombination layer has a small resistance, a nearly ohmic contact, and a negligible optical absorption.

  6. Intercellular communication of notochord cells during their differentiation in Cynops orientalis

    Institute of Scientific and Technical Information of China (English)

    ZENGMIBAI; YINGWANG; 等

    1993-01-01

    Intercellular communication of notochord cells during their differentiation was studied by microinjection of a fluorescent dye.Lucifer Yellow,Close correlation existed between the incidences of dye coupling and quantitative evaluation of gap junctions.high incidences of dye coupling and of gap junctions occurred at a stage when notochord cells were active in the change of cell shape and cell arrangement.With the subsidence of cell movements,both dye coupling and gap junctions were reduced to lower levels.It was,therefore,Suggested that intercellular communication via gap junctions played an important role in the coordination of notochord cell movements.Gap Junctions of altered configuration occurred in notochord cells in late taibud stage.The comparison of incidences of dye coupling at this stage with those at other stages strongly suggested that the gap junctions of altered configuration functioned just as those of generalized type.

  7. Lactic Acid Bacteria Improves Peyer's Patch Cell-Mediated Immunoglobulin A and Tight-Junction Expression in a Destructed Gut Microbial Environment.

    Science.gov (United States)

    Kim, Sung Hwan; Jeung, Woonhee; Choi, Il-Dong; Jeong, Ji-Woong; Lee, Dong Eun; Huh, Chul-Sung; Kim, Geun-Bae; Hong, Seong Soo; Shim, Jae-Jung; Lee, Jung Lyoul; Sim, Jae-Hun; Ahn, Young-Tae

    2016-06-28

    To evaluate the effects of lactic acid bacteria (LAB) on Peyer's patch cells, mice were treated with a high dose of kanamycin to disturb the gut microbial environment. The overarching goal was to explore the potential of LAB for use as a dietary probiotic that buffers the negative consequences of antibiotic treatment. In vitro, LAB stimulated the production of immunoglobulin A (IgA) from isolated Peyer's patch cells. Inflammation-related genes (TNF-α, IL-1β, and IL-8) were up-regulated in Caco-2 cells stimulated with lipopolysaccharide (LPS), while tight-junction-related genes (ZO-1 and occludin) were down-regulated; the effects of LPS on inflammatory gene and tight-junction gene expression were reversed by treatment with LAB. Mice treated with a high dose of kanamycin showed increased serum IgE levels and decreases in serum IgA and fecal IgA levels; the number of Peyer's patch cells decreased with kanamycin treatment. However, subsequent LAB treatment was effective in reducing the serum IgE level and recovering the serum IgA and fecal IgA levels, as well as the number of Peyer's patch cells. In addition, ZO-1 and occludin mRNA levels were up-regulated in the ileum tissues of mice receiving LAB treatment. Lactic acid bacteria can enhance the intestinal immune system by improving the integrity of the intestinal barrier and increasing the production of IgA in Peyer's patches. Lactic acid bacteria should be considered a potential probiotic candidate for improving intestinal immunity, particularly in mitigating the negative consequences of antibiotic use. PMID:26975767

  8. 基于三结太阳电池的透射率测量系统%Transmittance measurement system based on triple-junction solar cells

    Institute of Scientific and Technical Information of China (English)

    赵慧洁; 唐吾; 张颖; 张庆祥

    2012-01-01

    The degradation of solar cells' coatings in space environment will shorten space aircraft's fight life.So the research of the system which can measure the coatings transmittance's change is important.The transmittance measurement system was constructed by two triple-junction solar cells,one of which was covered with the glass sample and another was not.The triple-junction solar cells were used as detectors to measure solar flux.The photocurrent measurement circuits convert the photocurrent to analog volt,which will be multiplied and filtered.And the volt was translated to digital signal,which is transferred to the computer finally.The photocurrent signals of two triple-junction solar cells were acquired to calculate the overall transmittance in the solar cell responding spectrum,by using two channels comparing measurement method.The solar cells operation temperature was monitored by platinum-chip temperature sensors,in order to avoid measurement error which is induced by temperature change.The measurement relative error of system is about 0.1%,and the measurement uncertainty is less than 0.15%,which is proved by experiment.%在空间环境中太阳电池的涂层会发生退化,从而影响航天器的飞行寿命,因此研究能够测量涂层光学透射率变化的系统具有重要意义.使用三结太阳电池作为探测器接收光能量;设计光电流检测电路,对太阳电池输出电流进行电流-电压变换,放大,滤波和模数转换,最终输入上位机处理;运用双通道比对测量技术,比较有玻璃和无玻璃的三结太阳电池光电流测量值,计算出玻璃样片在三结太阳电池响应谱段内的整体透射率;使用热电阻传感器检测太阳电池工作温度以消除温度变化带来的误差.通过实验测得系统的测试相对误差约为0.1%,测量不确定度小于0.15%.

  9. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, T; Tomasulo, S; Lang, JR; Lee, ML

    2015-03-07

    We have investigated similar to 2.0 eV (AlxGa1-x)(0.51)In0.49P and similar to 1.9 eV Ga0.51In0.49P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (AlxGa1-x)(0.51)In0.49P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (V-oc) ranging from 1.29 to 1.30 V for Ga0.51In0.49P cells, and 1.35-1.37 V for (AlxGa1-x)(0.51)In0.49P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (W-oc = E-g/q - V-oc) of Ga0.51In0.49P cells to decrease from similar to 575 mV to similar to 565 mV, while that of (AlxGa1-x)(0.51)In0.49P cells remained nearly constant at 620 mV. The constant Woc as a function of substrate offcut for (AlxGa1-x)(0.51)In0.49P implies greater losses from non-radiative recombination compared with the Ga0.51In0.49P devices. In addition to larger Woc values, the (AlxGa1-x)(0.51)In0.49P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga0.51In0.49P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (AlxGa1-x)(0.51)In0.49P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells. (C) 2015 AIP Publishing LLC.

  10. Sarcomatoid chromophobe renal cell carcinoma: Cytohistopathological correlation of a case

    OpenAIRE

    Chakrabarti Indranil; Giri Amita; Majumdar Kaushik; DE, Anuradha

    2010-01-01

    Sarcomatoid renal cell carcinomas of the kidney are rare neoplasms constituting about 1-5% of all renal malignant neoplasms. These are aggressive tumors and are commonly associated with conventional (clear cell) renal cell carcinomas, but cases associated with chromophobe renal cell carcinomas are sparse. Cytological features of such lesions have rarely been reported. Here, we report a unique case of a 48-year-old male patient who presented with right flank lump and pain. A fine needle...

  11. Antiproliferative Action of Conjugated Linoleic Acid on Human MCF-7 Breast Cancer Cells Mediated by Enhancement of Gap Junctional Intercellular Communication through Inactivation of NF-κB

    Directory of Open Access Journals (Sweden)

    Md. Abdur Rakib

    2013-01-01

    Full Text Available The major conjugated linoleic acid (CLA isomers, c9,t11-CLA and t10,c12-CLA, have anticancer effects; however, the exact mechanisms underlying these effects are unknown. Evidence suggests that reversal of reduced gap junctional intercellular communication (GJIC in cancer cells inhibits cell growth and induces cell death. Hence, we determined that CLA isomers enhance GJIC in human MCF-7 breast cancer cells and investigated the underlying molecular mechanisms. The CLA isomers significantly enhanced GJIC of MCF-7 cells at 40 μM concentration, whereas CLA inhibited cell growth and induced caspase-dependent apoptosis. CLA increased connexin43 (Cx43 expression both at the transcriptional and translational levels. CLA inhibited nuclear factor-κB (NF-κB activity and enhanced reactive oxygen species (ROS generation. No significant difference was observed in the efficacy of c9,t11-CLA and t10,c12-CLA. These results suggest that the anticancer effect of CLA is associated with upregulation of GJIC mediated by enhanced Cx43 expression through inactivation of NF-κB and generation of ROS in MCF-7 cells.

  12. Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

    KAUST Repository

    Wang, Mingkui

    2009-01-01

    We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. © 2009 The Royal Society of Chemistry.

  13. The junctional complex in the intestine of Sagitta setosa (Chaetognatha): the paired septate junction.

    Science.gov (United States)

    Duvert, M; Gros, D; Salat, C

    1980-04-01

    The junctional complex of the intestine of Sagitta setosa has been studied in tissues stained with uranyl acetate or after lanthanum impregnation, and by freeze-cleavage. All types of junctions have been characterized in both perpendicular and tangential planes. From the apex to the base of the cell the following junctions occur in this order: a zonula adhaerens; a septate junction where the septa occur in pairs; a pleated sheet septate junction; and numerous gap junctions of the A-type. From the upper part of the cells inwards to the septate junction, the membranes follow a relatively straight path. In the lower part of the cells the membranes are deeply interdigitating. At the intersection between 3 cells a very different junction is to be observed where small units, periodically disposed, bind the membranes of the 3 adjoining cells. Each unit is composed of 3 short segments which bind the cell membranes to a central ring 16.6 +/- 2.3 nm in outer diameter. The paired septate junction constitutes a new type. Its main features are that the septa are paired and occur in 2 formations, one the 'loose formation', with elements between the septa of each pair, and the other, a 'tight formation'. After lanthanum impregnation, the thickness of each septum is seen to be about 3 nm and the undulation period 12.6 +/- 1.6 nm. On freeze-fractures 10-nm particles are found on crests on the PF face and in furrows on the EF face. The possible significance of this type of junction is discussed. The junctional complex described is analogous to those found in various invertebrate epithelia. PMID:6105159

  14. Experimental study of liquid-immersion III–V multi-junction solar cells with dimethyl silicon oil under high concentrations

    International Nuclear Information System (INIS)

    Highlights: • Electrical performance of MJ solar cells immersed by silicon oil was studied under 500×. • Theoretical cell photocurrent losses caused by silicon oil absorption were estimated. • Cell performance changes operated in silicon oil (1.0–30.0 mm) were analyzed. • Critical silicon oil thickness on top of MJ solar cells was estimated to be 6.3 mm. - Abstract: In order to better apply direct liquid-immersion cooling (LIC) method in temperature control of solar cells in high concentrating photovoltaic (CPV) systems, electrical characteristics of GaInP/GaInAs/Ge triple-junction solar cells immersed in dimethyl silicon oil of 1.0–30.0 mm thickness were studied experimentally under 500 suns and 25 °C. Theoretical photocurrent losses caused by spectrum transmittance decrease from spectral absorption of silicon oil were estimated for three series sub-cells, and an in-depth analysis of the electrical performances changes of the operated cell in silicon oil was performed. Compared with cell performances without liquid-immersion, the conversion efficiency and the maximum output power of the immersed solar cell in silicon oil of 1.0 mm thickness has increased from 39.567% and 19.556 W to 40.572% and 20.083 W respectively. However, the cell electrical performances decrease with increasing silicon oil thickness in the range of 1.0–30.0 mm, and the efficiency and the maximum output power of the cell have become less than those without liquid-immersion when the silicon oil thickness exceeds 6.3 mm

  15. Characterization of the InGaP/InGaAs/Ge triple-junction solar cell with a two-stage dish-style concentration system

    International Nuclear Information System (INIS)

    Highlights: • A mathematical model of triple-junction solar cell is established. • The calculated results compare well with outdoor experimental data. • A high efficiency heat pipe exchanger is specially designed to cool the cell. • The effect of the homogenizer is more significant at small direct solar radiation. • The impact of solar radiation on the experimental error is researched. - Abstract: Research on automatic tracking solar concentrator photovoltaic systems has gained increasing focus recently in order to develop high efficient solar PV technologies. A paraboloidal concentrator with a secondary optical system (with a concentration ratio in the range of 100–200×) and a sun tracking system was developed in this work. The performance of a heat-pipe cooled triple-junction GaInP/GalnAs/Ge solar cell was characterized. The experiments showed that the system achieved an average output power of 1.52 W/cm2 and an average efficiency of 29.3% when average direct solar radiation is 450 W/m2, while keeping the maximum cell temperature below 64.9 °C, which were 23.3% and 9.1% higher than those of single stage concentrating system respectively. Moreover, the experimental error is increases with the solar radiation. The experimental results for Voc and Isc compared reasonable well with the predictions from a mathematical model, and the calculated values were out of the measured error, which suggested that the model can be used to analyze the influence of relevant parameters on the performance of high concentration photovoltaic systems

  16. On-Orbit Demonstration Of Thin-Film Multi-Junction Solar Cells And Lithium-Ion Capacitors As Bus Components

    Science.gov (United States)

    Kukita, Akio; Takahashi, Masato; Shimazaki, Kazunori; Toyota, Hiroyuki; Imaizumi, Mitsuru; Kobayashi, Yuki; Takamoto, Tatsuya; Uno, Masatoshi; Shimada, Takanobu

    2011-10-01

    This paper describes an on-orbit demonstration plan for a lightweight solar panel using thin-film multi-junction (MJ) solar cells and aluminum-laminated lithium-ion capacitors (LICs). Thin-film MJ solar cells such as inverted metamorphic InGaP/GaAs/InGaAs 3J cells have flexibility as well as conversion efficiencies superior to conventional rigid 3J solar cells. A substantial reduction of satellite mass is achieved by the combination of thin-film MJ solar cells and light flexible paddles. An LIC is a hybrid-type capacitor that uses activated carbon as the cathode and carbon material pre-doped with lithium ion as the anode. LICs can be rapidly charged and discharged, and can operate in a wide temperature range for long periods. LICs are therefore suitable for long-term missions such as planetary explorations. Although these devices are very promising, so far there has been no opportunity to demonstrate their use in orbit. A lightweight thin solar panel with thin-film MJ solar cells will be installed on the Small Scientific Satellite Platform for Rapid Investigation and Test-A (SPRINT-A) satellite, which will be launched on the Epsilon launch vehicle in 2013. Utilizing the capacitor-like voltage behavior of LICs, we will employ a simple constant-power charging circuit without feedback control.

  17. Correlative Cryo-electron Tomography and Optical Microscopy of Cells

    OpenAIRE

    Zhang, Peijun

    2013-01-01

    The biological processes occurring in a cell are complex and dynamic, and to achieve a comprehensive understanding of the molecular mechanisms underlying these processes, both temporal and spatial information is required. While cryo-electron tomography (cryoET) provides three-dimensional (3D) still pictures of near-native state cells and organelles at molecular resolution, fluorescence light microscopy (fLM) offers movies of dynamic cellular processes in living cells. Combining and integratin...

  18. Solitons in Josephson junctions

    Science.gov (United States)

    Ustinov, A. V.

    1998-11-01

    Magnetic flux quanta in Josephson junctions, often called fluxons, in many cases behave as solitons. A review of recent experiments and modelling of fluxon dynamics in Josephson circuits is presented. Classic quasi-one-dimensional junctions, stacked junctions (Josephson superlattices), and discrete Josephson transmission lines (JTLs) are discussed. Applications of fluxon devices as high-frequency oscillators and digital circuits are also addressed.

  19. miR156a Mimic Represses the Epithelial-Mesenchymal Transition of Human Nasopharyngeal Cancer Cells by Targeting Junctional Adhesion Molecule A.

    Directory of Open Access Journals (Sweden)

    Yunhong Tian

    Full Text Available MicroRNAs (miRNAs have been documented as having an important role in the development of cancer. Broccoli is very popular in large groups of the population and has anticancer properties. Junctional adhesion molecule A (JAMA is preferentially concentrated at tight junctions and influences cell morphology and migration. Epithelial-mesenchymal transition (EMT is a developmental program associated with cancer progression and metastasis. In this study we aimed to investigate the role of miRNAs from broccoli in human nasopharyngeal cancer (NPC. We demonstrated that a total of 84 conserved miRNAs and 184 putative novel miRNAs were found in broccoli by sequencing technology. Among these, miR156a was expressed the most. In addition, synthetic miR156a mimic inhibited the EMT of NPC cells in vitro. Furthermore, it was confirmed that JAMA was the target of miR156a mimic as validated by 3' UTR luciferase reporter assays and western blotting. Knockdown of JAMA was consistent with the effects of miR156a mimic on the EMT of NPC, and the up-regulation of JAMA could partially restore EMT repressed by miR156a mimic. In conclusion, these results indicate that the miR156a mimic inhibits the EMT of NPC cells by targeting the 3' UTR of JAMA. These miRNA profiles of broccoli provide a fundamental basis for further research. Moreover, the discovery of miR156a may have clinical implications for the treatment of patients with NPC.

  20. Electron transport in molecular junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun

    charge position are in quantitative agreement with the experiments, while pure DFT is not. This is the consequence of the accurate energy level alignment, where the DFT+∑ method corrects the self-interaction error in the standard DFT functional and uses a static image charge model to include the image......This thesis addresses the electron transport in molecular junctions, focusing on the energy level alignment and correlation effects. Various levels of theory have been applied to study the structural and electronic effects in different molecular junctions, starting from the single particle density...... the lowest unoccupied molecular level (LUMO) of the 44BP molecule hybridizes strongly with Ni 3d orbitals, the gating is auxiliary by the so-called spinterface. Finally, the correlation effect of the image charge beyond the energy level renormalization has been studied. It is shown that the finite response...

  1. Counting Statistics in Nanoscale Junctions

    OpenAIRE

    Liu, Yu-Shen; Chen, Yu-Chang

    2010-01-01

    We present first-principles calculations for moments of the current up to the third order in atomic-scale junctions. The quantum correlations of the current are calculated using the current operator in terms of the wave functions obtained self-consistently within the static density-functional theory. We investigate the relationships of the conductance, the second, and the third moment of the current for carbon atom chains of various lengths bridging two metal electrodes in the linear and nonl...

  2. Theoretical design and performance of In{sub x}Ga{sub 1-x}N two-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaobin; Wang Xiaoliang; Xiao Hongling; Yang Cuibai; Ran Junxue; Wang Cuimei; Hou Qifeng; Li Jinmin [Materials Science Center, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China); Wang Zhanguo [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083 (China)], E-mail: xbzhang@semi.ac.cn

    2008-12-21

    The efficiencies of In{sub x}Ga{sub 1-x}N two-junction solar cells are calculated with various bandgap combinations of subcells under AM1.5 global, AM1.5 direct and AM0 spectra. The influence of top-cell thickness on efficiency has been studied and the performance of In{sub x}Ga{sub 1-x}N cells for the maximum light concentration of various spectra has been evaluated. Under one-sun irradiance, the optimum efficiency is 35.1% for the AM1.5 global spectrum, with a bandgap combination of top/bottom cells as 1.74 eV/1.15 eV. And the limiting efficiency is 40.9% for the highest light concentration of the AM1.5 global spectrum, with the top/bottom cell bandgap as 1.72 eV/1.12 eV.

  3. Studies of Redox Equilibria at Elevated Temperatures 2. An Automatic Divided-Function Autoclave and Cell with Flowing Liquid Junction for Electrochemical Measurements on Aqueous Systems

    International Nuclear Information System (INIS)

    An apparatus is described that has been developed for electrochemical studies of aqueous systems at temperatures above 100 deg C. It consists essentially of an electrically heated experimental cell enclosed by a separate pressure-vessel the walls of which are kept cool. This construction eliminates or reduces the problems of sealing electrical connections and of the corrosion of the pressure vessel, that commonly arise with conventional, externally-heated autoclaves. Pressure is applied to the cell by means of compressed air, diaphragm valves at the electrolyte outlet automatically maintaining the pressure in the cell about 1 atm lower than that in the pressure vessel. Two independent streams of electrolyte can be pumped into the experimental cell a special form of which has been developed in which may be formed a galvanic cell with a continuously regenerated flowing-liquid junction. In this form the apparatus enables experiments with, for example, one molal chloride solutions with pH 1-10, at temperatures up to about 250 deg C and under pressures up to about 40 atm. The apparatus has been tested in experiments in which classical measurements of the conductance of some aqueous electrolytes have been repeated. Good agreement with the earlier results has been obtained

  4. Junction characteristics and current conduction mechanisms of GaInP2 n+p diodes and solar cells. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, K.C.

    1994-12-01

    This work involves an investigation of GaInP2 n+p diode and solar cell dark current mechanisms, the defect centers that affect these mechanisms, and the response of dark current and solar cell photovoltaic parameters to I MeV electron irradiation and thermal annealing. Dark current due to carrier diffusion, recombination, and tunneling were identified, and recombination current was found to dominate at the maximum power-point voltage of the GaInP2 solar cells. Carrier recombination was found to occur via defect centers at the perimeter and within the bulk of the junction. Two deep majority-hole trap centers were found at Ea1 = Et - Ev approx. 0.45eV and Ea2 = Et- Ev approx. 0.05eV. Dark current due to carrier tunneling was dominant in `leaky` diodes and solar cells that contained line-like morphological defects believed to be due to lattice mismatch between GaInP2 and GaAs. The effects of 1 MeV electron irradiation and thermal annealing on solar cell and diode dark current mechanisms and efficiency were also studied.

  5. The intracellular domain of cadherin-11 is not required for the induction of cell aggregation, adhesion or gap-junction formation.

    Science.gov (United States)

    Braungart, E; Hartman, E; Bechler, K; Höfler, H; Atkinson, M J

    2001-01-01

    The cadherin family of cell adhesion molecules demonstrates calcium-dependent homophilic binding, leading to cellular recognition and adhesion. The adhesion mediated by the classical type I cadherins is strengthened through catenin-mediated coupling of the cytoplasmic domain to the cytoskeleton. This cytoskeletal interaction may not be essential for the adhesion promoted by all cadherins, several of which lack cytosolic catenin-binding sequences. Cadherin-11, a classical cadherin, possesses a cytoplasmic domain that interacts with catenins, but may also occur as a variant form expressing a truncated cytoplasmic domain. To study the role of the cytoplasmic sequence in cadherin-11 mediated adhesion we have constructed and expressed a truncated cadherin-11 protein lacking the cytoplasmic domain and unable to bind beta-catenin. Expression of the truncated cadherin-11 in MDA-MB-435S human mammary carcinoma cells reduced their motility and promoted calcium-dependent cell aggregation, frequent cell contacts, and functional gap-junctions. We conclude that the intracellular catenin-binding domain of cadherin-11, and by inference cytoskeletal interaction, is not required for the initiation and formation of cell adhesion. PMID:11775026

  6. Differential detection of alternatively spliced variants of Ciz1 in normal and cancer cells using a custom exon-junction microarray

    International Nuclear Information System (INIS)

    Ciz1 promotes initiation of mammalian DNA replication and is present within nuclear matrix associated DNA replication factories. Depletion of Ciz1 from normal and cancer cells restrains entry to S phase and inhibits cell proliferation. Several alternative splicing events with putative functional consequences have been identified and reported, but many more variants are predicted to exist based on publicly available mRNAs and expressed sequence tags. Here we report the development and validation of a custom exon and exon-junction microarray focused on the human CIZ1 gene, capable of reproducible detection of differential splice-variant expression. Using a pair of paediatric cancer cell lines and a pool of eight normal lines as reference, the array identified expected and novel CIZ1 splicing events. One novel variant (delta 8-12) that encodes a predicted protein lacking key functional sites, was validated by quantitative RT-PCR and found to be over-represented in a range of other cancer cell lines, and over half of a panel of primary lung tumours. Expression of CIZ1 delta 8-12 appears to be restricted to cancer cells, and may therefore be a useful novel biomarker

  7. Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

    International Nuclear Information System (INIS)

    The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implanted phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.

  8. Prevalence and correlates of cell phone use among Texas drivers

    OpenAIRE

    Michelle L. Wilkinson; Brown, Austin L.; Iman Moussa; R. Sue Day

    2015-01-01

    Introduction: Cell phone use while driving restricts peripheral awareness and impairs reaction time. This study assessed the 3-year prevalence of cell phone use (CPU) of drivers and characteristics associated with its use in six cities across Texas, 2011–2013. Methods: CPU and driver characteristics were observed among motor vehicles (n = 1280) stopped at major intersections in medical and academic campuses. A multivariable logistic regression model described the association between driver...

  9. Merkel Cell Carcinoma: Correlation of KIT Expression with Survival and Evaluation of KIT Gene Mutational Status

    OpenAIRE

    Andea, Aleodor A.; Patel, Raj; Ponnazhagan, Selvarangan; Kumar, Sanjay; DeVilliers, Patricia; Jhala, Darshana; Eltoum, Isam E.; Siegal, Gene P.

    2010-01-01

    Merkel cell carcinoma is one of the most aggressive primary cutaneous malignancies. Since some Merkel cell carcinomas express the receptor tyrosine kinase KIT, we aimed to evaluate the correlation of KIT expression with outcome and the presence of activating mutations in the KIT gene in Merkel cell carcinoma.

  10. Intestinal Cell Tight Junctions Limit Invasion of Candida albicans through Active Penetration and Endocytosis in the Early Stages of the Interaction of the Fungus with the Intestinal Barrier.

    Directory of Open Access Journals (Sweden)

    Marianne Goyer

    Full Text Available C. albicans is a commensal yeast of the mucous membranes in healthy humans that can also cause disseminated candidiasis, mainly originating from the digestive tract, in vulnerable patients. It is necessary to understand the cellular and molecular mechanisms of the interaction of C. albicans with enterocytes to better understand the basis of commensalism and pathogenicity of the yeast and to improve the management of disseminated candidiasis. In this study, we investigated the kinetics of tight junction (TJ formation in parallel with the invasion of C. albicans into the Caco-2 intestinal cell line. Using invasiveness assays on Caco-2 cells displaying pharmacologically altered TJ (i.e. differentiated epithelial cells treated with EGTA or patulin, we were able to demonstrate that TJ protect enterocytes against invasion of C. albicans. Moreover, treatment with a pharmacological inhibitor of endocytosis decreased invasion of the fungus into Caco-2 cells displaying altered TJ, suggesting that facilitating access of the yeast to the basolateral side of intestinal cells promotes endocytosis of C. albicans in its hyphal form. These data were supported by SEM observations of differentiated Caco-2 cells displaying altered TJ, which highlighted membrane protrusions engulfing C. albicans hyphae. We furthermore demonstrated that Als3, a hypha-specific C. albicans invasin, facilitates internalization of the fungus by active penetration and induced endocytosis by differentiated Caco-2 cells displaying altered TJ. However, our observations failed to demonstrate binding of Als3 to E-cadherin as the trigger mechanism of endocytosis of C. albicans into differentiated Caco-2 cells displaying altered TJ.

  11. Beta-sitosterol from psyllium seed husk (Plantago ovata Forsk) restores gap junctional intercellular communication in Ha-ras transfected rat liver cells.

    Science.gov (United States)

    Nakamura, Yasushi; Yoshikawa, Noriko; Hiroki, Ikumi; Sato, Kenji; Ohtsuki, Kozo; Chang, Chia-Cheng; Upham, Brad L; Trosko, James E

    2005-01-01

    We purified compounds from the husks of psyllium seeds (Plantago ovata Forsk; desert Indian wheat), beginning with an ethanol extraction then followed by HP-20 and silica gel chromatography, which restored gap junctional intercellular communication (GJIC) in v-Ha-ras transfected rat liver epithelial WB-F344 cell line (WB-Ha-ras). GJIC was assessed by a scrape loading dye transfer assay. The active compound was identified as beta-sitosterol based on gas chromatography retention times and electron ionization mass spectroscopy (EI-MS) spectrum of authentic beta-sitosterol. Authentic beta-sitosterol restored GJIC in the tumorigenic WB-Ha-ras GJIC-deficient cells at a dose of 2.4 microM. In addition, a similar phytosterol, stigmasterol, also restored GJIC, albeit at a lower activity. beta-sitosterol and stigmasterol increased the level of connexin43 protein (Cx43) and restored phosphorylation of Cx43 to levels similar to the parental nontransfected cell line. We concluded that the restoration of intercellular communication in the GJIC-deficient, tumorigenic WB-Ha-ras cell line by the ethanol soluble fraction of psyllium seed husks is largely due to the presence of the phytosterol, beta-sitosterol. We discuss implications for dietary modulation of cancer by beta-sitosterol. PMID:15860444

  12. T1 relaxation in renal cell carcinoma with pathologic correlation

    International Nuclear Information System (INIS)

    Renal cell carcinoma, unlike most tumors, can have a shorter T1 on MR imaging than its host tissue. The author compared the signal intensity of renal tumor and normal renal tissue on T1 images obtained using contrast agents. A short T1 signal was seen in 16 of 23 cases of clear cells and/or hemorrhage. In six of eight cases with a long T1 signal, necrosis was found on gross pathologic examination. In four of five cases of isointense signal an unusual pathology was found; one of the five patients was in end-stage renal failure. Fat-containing clear cells and hemorrhage produce a short T1 signal, whereas necrosis produces a long T1 signal

  13. The protein kinase A pathway contributes to Hg2+-induced alterations in phosphorylation and subcellular distribution of occludin associated with increased tight junction permeability of salivary epithelial cell monolayers.

    Science.gov (United States)

    Kawedia, Jitesh D; Jiang, Mengmeng; Kulkarni, Amit; Waechter, Holly E; Matlin, Karl S; Pauletti, Giovanni M; Menon, Anil G

    2008-09-01

    Hg(2+) is commonly used as an inhibitor of many aquaporins during measurements of transcellular water transport. To investigate whether it could also act on the paracellular water transport pathway, we asked whether addition of Hg(2+) affected transport of radiolabeled probes through tight junctions of a salivary epithelial cell monolayer. Inclusion of 1 mM Hg(2+) decreased transepithelial electrical resistance by 8-fold and augmented mannitol and raffinose flux by 13-fold, which translated into an estimated 44% increase in pore radius at the tight junction. These Hg(2+)-induced effects could be partially blocked by the protein kinase A (PKA) inhibitor N-[2-((p-bromocinnamyl) amino) ethyl]-5-isoquinolinesulfonamide, 2HCl (H89), suggesting that both-PKA dependent and PKA-independent mechanisms contribute to tight junction regulation. Western blot analyses showed a 2-fold decrease in tight junction-associated occludin after Hg(2+) treatment and the presence of a novel hyperphosphorylated form of occludin in the cytoplasmic fraction. These findings were corroborated by confocal imaging. The results from this study reveal a novel contribution of the PKA pathway in Hg(2+)-induced regulation of tight junction permeability in the salivary epithelial barrier. Therapeutically, this could be explored for pharmacological intervention in the treatment of dry mouth, Sjögren's syndrome, and possibly other disorders of fluid transport. PMID:18550693

  14. Hexavalent chromium at low concentration alters Sertoli cell barrier and connexin 43 gap junction but not claudin-11 and N-cadherin in the rat seminiferous tubule culture model

    Energy Technology Data Exchange (ETDEWEB)

    Carette, Diane [INSERM U 1065, Team 5 “Physiopathology of Germ Cell Control: Genomic and Non Genomic Mechanisms” C3M, University of Nice Sophia Antipolis, Nice (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Perrard, Marie-Hélène, E-mail: marie-helene.durand@ens-lyon.fr [Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon I, CNRS, INRA, Ecole Normale Supérieure de Lyon, Lyon (France); Prisant, Nadia [University of Versailles/St Quentin-en-Yvelines (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Gilleron, Jérome; Pointis, Georges [INSERM U 1065, Team 5 “Physiopathology of Germ Cell Control: Genomic and Non Genomic Mechanisms” C3M, University of Nice Sophia Antipolis, Nice (France); Segretain, Dominique [University of Versailles/St Quentin-en-Yvelines (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Durand, Philippe [Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon I, CNRS, INRA, Ecole Normale Supérieure de Lyon, Lyon (France); Kallistem SAS Ecole Normale Supérieure de Lyon, Lyon (France)

    2013-04-01

    Exposure to toxic metals, specifically those belonging to the nonessential group leads to human health defects and among them reprotoxic effects. The mechanisms by which these metals produce their negative effects on spermatogenesis have not been fully elucidated. By using the Durand's validated seminiferous tubule culture model, which mimics the in vivo situation, we recently reported that concentrations of hexavalent chromium, reported in the literature to be closed to that found in the blood circulation of men, increase the number of germ cell cytogenetic abnormalities. Since this metal is also known to affect cellular junctions, we investigated, in the present study, its potential influence on the Sertoli cell barrier and on junctional proteins present at this level such as connexin 43, claudin-11 and N-cadherin. Cultured seminiferous tubules in bicameral chambers expressed the three junctional proteins and ZO-1 for at least 12 days. Exposure to low concentrations of chromium (10 μg/l) increased the trans-epithelial resistance without major changes of claudin-11 and N-cadherin expressions but strongly delocalized the gap junction protein connexin 43 from the membrane to the cytoplasm of Sertoli cells. The possibility that the hexavalent chromium-induced alteration of connexin 43 indirectly mediates the effect of the toxic metal on the blood–testis barrier dynamic is postulated. - Highlights: ► Influence of Cr(VI) on the Sertoli cell barrier and on junctional proteins ► Use of cultured seminiferous tubules in bicameral chambers ► Low concentrations of Cr(VI) (10 μg/l) altered the trans-epithelial resistance. ► Cr(VI) did not alter claudin-11 and N-cadherin. ► Cr(VI) delocalized connexin 43 from the membrane to the cytoplasm of Sertoli cells.

  15. Reciprocal influence of connexins and apical junction proteins on their expressions and functions

    OpenAIRE

    Derangeon, Mickaël; Spray, David C.; Bourmeyster, Nicolas; Sarrouilhe, Denis; Hervé, Jean-Claude

    2008-01-01

    Membranes of adjacent cells form intercellular junctional complexes to mechanically anchor neighbour cells (anchoring junctions), to seal the paracellular space and to prevent diffusion of integral proteins within the plasma membrane (tight junctions) and to allow cell-to-cell diffusion of small ions and molecules (gap junctions). These different types of specialised plasma membrane microdomains, sharing common adaptor molecules, particularly zonula occludens proteins, frequently present inte...

  16. Correlation between myeloid-derived suppressor cells and gastric cancer begin with chronic gastritis

    Institute of Scientific and Technical Information of China (English)

    朱立宁

    2012-01-01

    Objective To investigate the correlation between the ratio change of circulating myeloid-derived suppressor cells(MDSCs) and cellular immune function in healthy volunteers,chronic gastritis patients,gastric intraepithelial neoplasia patients and gastric cancer patients

  17. "Collective coding" of correlated cone signals in the retinal ganglion cell.

    OpenAIRE

    Tsukamoto, Y; R. G. Smith; Sterling, P

    1990-01-01

    The signals in neighboring cones are partially correlated due to local correlations of luminance in the visual scene. By summing these partially correlated signals, the retinal ganglion cell improves its signal/noise ratio (compared to the signal/noise ratio in a cone) and expands the variance of its response to fill its dynamic range. Our computations prove that the optimal weighting function for this summation is dome-shaped. The computations also show that (assuming a particular space cons...

  18. Fabrication of double- and triple-junction solar cells with hydrogenated amorphous silicon oxide (a-SiOx:H) top cell

    Czech Academy of Sciences Publication Activity Database

    Kim, D.Y.; Guijt, E.; Si, F.T.; Santbergen, R.; Holovský, Jakub; Isabella, O.; van Swaaij, R.A.C.M.M.; Zeman, M.

    2015-01-01

    Roč. 141, Oct (2015), s. 148-153. ISSN 0927-0248 R&D Projects: GA MŠk 7E12029 EU Projects: European Commission(XE) 283501 - Fast Track Institutional support: RVO:68378271 Keywords : multi-junction solar cel * a-SiOx:H * high voc * current matching Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.337, year: 2014

  19. Mixing of connexins in gap junction membrane channels.

    OpenAIRE

    Sosinsky, G

    1995-01-01

    Gap junctions are plaque-like clusters of intercellular channels that mediate intercellular communication. Each of two adjoining cells contains a connexon unit which makes up half of the whole channel. Gap junction channels are formed from a multigene family of proteins called connexins, and different connexins may be coexpressed by a single cell type and found within the same plaque. Rodent gap junctions contain two proteins, connexins 32 and 26. Use of a scanning transmission electron micro...

  20. Comparison of single junction AlGaInP and GaInP solar cells grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Taizo, E-mail: taizo.masuda@yale.edu; Tomasulo, Stephanie; Lang, Jordan R.; Lee, Minjoo Larry [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511 (United States)

    2015-03-07

    We have investigated ∼2.0 eV (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P and ∼1.9 eV Ga{sub 0.51}In{sub 0.49}P single junction solar cells grown on both on-axis and misoriented GaAs substrates by molecular beam epitaxy (MBE). Although lattice-matched (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P solar cells are highly attractive for space and concentrator photovoltaics, there have been few reports on the MBE growth of such cells. In this work, we demonstrate open circuit voltages (V{sub oc}) ranging from 1.29 to 1.30 V for Ga{sub 0.51}In{sub 0.49}P cells, and 1.35–1.37 V for (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells. Growth on misoriented substrates enabled the bandgap-voltage offset (W{sub oc} = E{sub g}/q − V{sub oc}) of Ga{sub 0.51}In{sub 0.49}P cells to decrease from ∼575 mV to ∼565 mV, while that of (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells remained nearly constant at 620 mV. The constant W{sub oc} as a function of substrate offcut for (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P implies greater losses from non-radiative recombination compared with the Ga{sub 0.51}In{sub 0.49}P devices. In addition to larger W{sub oc} values, the (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P cells exhibited significantly lower internal quantum efficiency (IQE) values than Ga{sub 0.51}In{sub 0.49}P cells due to recombination at the emitter/window layer interface. A thin emitter design is experimentally shown to be highly effective in improving IQE, particularly at short wavelengths. Our work shows that with further optimization of both cell structure and growth conditions, MBE-grown (Al{sub x}Ga{sub 1−x}){sub 0.51}In{sub 0.49}P will be a promising wide-bandgap candidate material for high-efficiency, lattice-matched multi-junction solar cells.

  1. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative......, and focuses on mechanism, structure/function relations, regimes and mechanisms of transport, some molecular regularities, and some substantial challenges facing the field. Because there are many regimes and mechanisms in transport junctions, we will discuss time scales, geometries, and inelastic scattering...

  2. Renal cell carcinoma: histological classification and correlation with imaging findings

    Energy Technology Data Exchange (ETDEWEB)

    Muglia, Valdair F., E-mail: fmuglia@fmrp.usp.br [Universidade de Sao Paulo (CCIFM/FMRP/USP), Ribeirao Preto, SP (Brazil). Centro de Ciencias das Imagens e Fisica Medica. Faculdade de Medicina; Prando, Adilson [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Hospital Vera Cruz, Campinas, SP (Brazil). Dept. de Imaginologia

    2015-05-15

    Renal cell carcinoma (RCC) is the seventh most common histological type of cancer in the Western world and has shown a sustained increase in its prevalence. The histological classification of RCCs is of utmost importance, considering the significant prognostic and therapeutic implications of its histological subtypes. Imaging methods play an outstanding role in the diagnosis, staging and follow-up of RCC. Clear cell, papillary and chromophobe are the most common histological subtypes of RCC, and their preoperative radiological characterization, either followed or not by confirmatory percutaneous biopsy, may be particularly useful in cases of poor surgical condition, metastatic disease, central mass in a solitary kidney, and in patients eligible for molecular targeted therapy. New strategies recently developed for treating renal cancer, such as cryo and radiofrequency ablation, molecularly targeted therapy and active surveillance also require appropriate preoperative characterization of renal masses. Less common histological types, although sharing nonspecific imaging features, may be suspected on the basis of clinical and epidemiological data. The present study is aimed at reviewing the main clinical and imaging findings of histological RCC subtypes. (author)

  3. Renal cell carcinoma: histological classification and correlation with imaging findings

    International Nuclear Information System (INIS)

    Renal cell carcinoma (RCC) is the seventh most common histological type of cancer in the Western world and has shown a sustained increase in its prevalence. The histological classification of RCCs is of utmost importance, considering the significant prognostic and therapeutic implications of its histological subtypes. Imaging methods play an outstanding role in the diagnosis, staging and follow-up of RCC. Clear cell, papillary and chromophobe are the most common histological subtypes of RCC, and their preoperative radiological characterization, either followed or not by confirmatory percutaneous biopsy, may be particularly useful in cases of poor surgical condition, metastatic disease, central mass in a solitary kidney, and in patients eligible for molecular targeted therapy. New strategies recently developed for treating renal cancer, such as cryo and radiofrequency ablation, molecularly targeted therapy and active surveillance also require appropriate preoperative characterization of renal masses. Less common histological types, although sharing nonspecific imaging features, may be suspected on the basis of clinical and epidemiological data. The present study is aimed at reviewing the main clinical and imaging findings of histological RCC subtypes. (author)

  4. Degradation of connexins and gap junctions

    OpenAIRE

    Falk, Matthias M.; Kells, Rachael M.; Berthoud, Viviana M.

    2014-01-01

    Connexin proteins are short-lived within the cell, whether present in the secretory pathway or in gap junction plaques. Their levels can be modulated by their rate of degradation. Connexins, at different stages of assembly, are degraded through the proteasomal, endo-/lysosomal, and phago-/lysosomal pathways. In this review, we summarize the current knowledge about connexin and gap junction degradation including the signals and protein-protein interactions that participate in their targeting f...

  5. MreB Orientation Correlates with Cell Diameter in Escherichia coli.

    Science.gov (United States)

    Ouzounov, Nikolay; Nguyen, Jeffrey P; Bratton, Benjamin P; Jacobowitz, David; Gitai, Zemer; Shaevitz, Joshua W

    2016-09-01

    Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter. PMID:27602731

  6. Fluctuations, Correlations and the Estimation of Concentrations inside Cells

    Science.gov (United States)

    Pérez Ipiña, Emiliano; Ponce Dawson, Silvina

    2016-01-01

    Information transmission in cells occurs quite accurately even when concentration changes are “read” by individual binding sites. In this paper we study ligand number and site occupancy fluctuations when ligands diffuse and react going beyond the analyses that focus on their asymptotic decay. In this way we show that, for immobile binding sites, fluctuations in the number of bound molecules decay on a relatively fast scale before the asymptotic behavior kicks in. This result can explain the observed co-existence of highly fluctuating instantaneous transcriptional activities with accumulated mRNA concentrations that have relatively small noise levels. We also show that the initial stages of the decay in the bound molecule number fluctuations have one or two characteristic timescales depending on the concentration of free molecules. This transition can explain the changes in enzyme activity observed at the single molecule level. PMID:26962863

  7. Substrate dependent stability and interplay between optical and electrical properties in {mu}-c:SiH single junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Boccard, M.; Cuony, P.; Despeisse, M.; Domine, D.; Feltrin, A.; Wyrsch, N.; Ballif, C. [Ecole Polytechnique Federale de Lausanne (EPFL), Photovoltaics and Thin Film Electronics Laboratory, Rue A.-L. Breguet 2, CH-2000 Neuchatel (Switzerland)

    2011-01-15

    In this work, we analyze the effect of rough ZnO front electrodes developed in-house favoring high current versus ''smoother'' substrates favoring good V{sub oc} and FF on the properties of microcrystalline silicon ({mu}-c:SiH) cells. Complete {mu}-c:SiH p-i-n solar cells with intrinsic layer thicknesses varying from 1 to 6{mu}m were deposited using very high frequency plasma-enhanced chemical vapor deposition. The better scattering capabilities of rough substrates induce a significantly higher cell current in comparison to the smooth one for all the thicknesses. This allows a current output of more than 27 mA cm{sup -2} for cells thicker than 4{mu}m. As a result, there is no full compensation of poor light scattering by thickness increase up to 6{mu}m in {mu}-c:SiH solar cells. Concerning the electrical characteristics, good quality cells are obtained for all thicknesses on smooth substrates, whereas the thick cells on rough substrates exhibit poorer electrical characteristics. Cells grown on smooth substrates show excellent stability under light soaking and atmospheric storage for all the thicknesses. However, a high increase of the saturation current is evidenced after atmospheric storage for cells grown on rough substrates and thus a degradation of their electrical characteristics is observed. (author)

  8. Absence of correlation between rates of cell wall turnover and autolysis shown by Bacillus subtilis mutants.

    OpenAIRE

    Vitković, L; Cheung, H. Y.; Freese, E

    1984-01-01

    Bacillus subtilis mutants with reduced rates of cell wall autolysis reached a constant rate of wall turnover after a longer lag than the standard strain but eventually showed the same turnover rate. In reverse, a turnover-deficient mutant autolysed at a slightly higher rate than the standard strain. Consequently, there is no correlation between the rates of cell wall turnover and autolysis.

  9. 17β estradiol regulation of connexin 43-based gap junction and mechanosensitivity through classical estrogen receptor pathway in osteocyte-like MLO-Y4 cells.

    KAUST Repository

    Ren, Jian

    2013-04-01

    Connexin 43 (Cx43) plays an essential role in osteocyte mechanotransduction. Although estrogen involves in the adaptive responses of bone cells to mechanical loadings, its effects on osteocytic Cx43-based gap junction intercellular communication (GJIC) remain obscure. We found that 17β estradiol (E2) up-regulated Cx43, and enhanced GJIC in osteocyte-like MLO-Y4 cells in fluorescence recovery after photobleaching (FRAP) assay. Combination of E2 pre-treatment and oscillating fluid flow (OFF) further enhanced Cx43 expression and mitogen-activated protein kinase (MAPK) phosphorylation, comparing to E2 or OFF treatment alone. Both blocking of classical estrogen receptors (ERα/β) by fulvestrant and ERα knockdown by small interfering RNA inhibited E2-mediated Cx43 increase, while a GPR30-specific agonist G-1 failed to promote Cx43 expression. Our results suggest that the presence of E2 enhanced Cx43-based GJIC mainly via ERα/β pathway, and sensitized osteocytes to mechanical loading. © 2012 Elsevier Inc. All rights reserved.

  10. Indomethacin induces increase in gastric epithelial tight junction permeability via redistribution of occludin and activation of p38 MAPK in MKN-28 Cells.

    Science.gov (United States)

    Thakre-Nighot, Meghali; Blikslager, Anthony T

    2016-01-01

    Tight Junctions (TJ) create a paracellular barrier that is compromised when nonsteriodal anti-inflammatory drugs (NSAIDs) injure the gastric epithelium, leading to increased permeability. However, the mechanism of NSAID-induced gastric injury is unclear. Here, we examined the effect of indomethacin on barrier function and TJ in gastric MKN-28 cells. In concentration response studies, 500 µm indomethacin induced a significant decrease in transepithelial resistance (TER; 380 vs. 220 Ω·cm(2) for control and indomethacin-treated cells respectively, p permeability by 0.2 vs 1.2 g/l (p permeability. Pretreatment with the p38 MAPK inhibitor significantly attenuated the disruption of barrier function, but JNK and MEK/ERK inhibition had no effect. Western blot analysis on gastric mucosa reveled loss of TJ protein occludin by indomethacin, which was prevented by inhibition of p38 MAPK. This data suggests that indomethacin compromises the gastric epithelial barrier via p38 MAPK inducing occludin alterations in the TJs. PMID:27583191

  11. 17β estradiol regulation of connexin 43-based gap junction and mechanosensitivity through classical estrogen receptor pathway in osteocyte-like MLO-Y4 cells.

    Science.gov (United States)

    Ren, Jian; Wang, Xu-Hui; Wang, Guang-Chao; Wu, Jun-Hua

    2013-04-01

    Connexin 43 (Cx43) plays an essential role in osteocyte mechanotransduction. Although estrogen involves in the adaptive responses of bone cells to mechanical loadings, its effects on osteocytic Cx43-based gap junction intercellular communication (GJIC) remain obscure. We found that 17β estradiol (E2) up-regulated Cx43, and enhanced GJIC in osteocyte-like MLO-Y4 cells in fluorescence recovery after photobleaching (FRAP) assay. Combination of E2 pre-treatment and oscillating fluid flow (OFF) further enhanced Cx43 expression and mitogen-activated protein kinase (MAPK) phosphorylation, comparing to E2 or OFF treatment alone. Both blocking of classical estrogen receptors (ERα/β) by fulvestrant and ERα knockdown by small interfering RNA inhibited E2-mediated Cx43 increase, while a GPR30-specific agonist G-1 failed to promote Cx43 expression. Our results suggest that the presence of E2 enhanced Cx43-based GJIC mainly via ERα/β pathway, and sensitized osteocytes to mechanical loading. PMID:23247057

  12. Broadband antireflection sub-wavelength structure of InGaP/InGaAs/Ge triple junction solar cell with composition-graded SiNx

    Science.gov (United States)

    Chung, Chen-Chen; Lo, Hsiao-Chieh; Lin, Yen-Ku; Yu, Hung-Wei; Tinh Tran, Binh; Lin, Kung-Liang; Chen, Yung Chang; Quan, Nguyen-Hong; Chang, Edward Yi; Tseng, Yuan-Chieh

    2015-05-01

    This work reports a fabrication strategy to improve the antireflective ability of a InGaP/GaAs/Ge triple-junction solar cell, by combining a nano-templating technique and a chemical-synthesis approach. SiH4 and N2 were used as ammonia-free reaction gases in a plasma-enhanced chemical vapor deposition (PECVD) to prepare Si3N4 as an original antireflective coating (ARC) layer with better chemical stability. Composition-graded SiNx was successfully integrated with sub-wavelength structure by modulating SiH4/N2 ratio during PECVD deposition, and followed by a controllable gold-nanoparticle masking technique on top of the solar cell. Finite-difference time-domain solution was employed to simulate and optimize the aspect-ratio of the ARC, under the condition of variable refractive index over a broad wavelength window, and followed by the masking technique to obtain the desired ARC dimension. This enabled a low light reflectance (advantages of structural optimization, better chemical stability and graded refractive index of the ARC. The solar cell’s performance was tested and showed great competitiveness to those of forefront studies, suggesting the feasibility of the proposed technology.

  13. Gene Expression Correlations in Human Cancer Cell Lines Define Molecular Interaction Networks for Epithelial Phenotype

    OpenAIRE

    Kohn, Kurt W.; Zeeberg, Barry M.; Reinhold, William C.; Pommier, Yves

    2014-01-01

    Using gene expression data to enhance our knowledge of control networks relevant to cancer biology and therapy is a challenging but urgent task. Based on the premise that genes that are expressed together in a variety of cell types are likely to functions together, we derived mutually correlated genes that function together in various processes in epithelial-like tumor cells. Expression-correlated genes were derived from data for the NCI-60 human tumor cell lines, as well as data from the Bro...

  14. Characterization of gap junctions by electrophysiological and electronmicroscopical methods

    OpenAIRE

    Hülser, Dieter F.; Paschke, Dietmar; Franz BRÜMMER; Eckert, Reiner

    1990-01-01

    Gap junctions are ubiquitous in the animal kingdom from mesozoa to vertebrates. They must be discriminated from desmosomes which anchor cells together to form structural or functional units as well as from tight junctions which seal membranes of epithelial cells to each other so that the paracellular path becomes impermeable to molecules and a polarity of apical and basolateral surface is maintained.

  15. Correlation of spatially resolved lifetime measurements with overall solar cell parameters

    Energy Technology Data Exchange (ETDEWEB)

    Isenberg, J.; Dicker, J.; Riepe, S.; Ballif, C.; Peters, S.; Lautenschlager, H.; Schindler, R.; Warta, W. [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany)

    2002-07-01

    Lifetime mappings are common tools for assessing the quality of mc-silicon for solar cell production. Nevertheless it is a difficult problem to directly relate lifetime mappings to overall solar cell parameters. This paper intends to show that this correlation is possible quantitatively. We have correlated actual low-level injection lifetimes obtained by carrier density imaging (CDI) measurements with overall cell parameters of solar cells processed on adjacent wafers. The 2D lifetime-structure is taken account for by appropriate weighing functions that include the whole information given in the frequency distribution of bulk lifetimes. Thus a one dimensional cell model (PC1D) can be applied. Good general agreement between predicted and measured cell parameters has been achieved, deviations are discussed. Further insight into the gettering behavior of block-cast and Bridgman-grown mc-silicon was attained. (orig.)

  16. Build them up and break them down: Tight junctions of cell lines expressing typical hepatocyte polarity with a varied repertoire of claudins.

    Science.gov (United States)

    Grosse, Brigitte; Degrouard, Jeril; Jaillard, Danielle; Cassio, Doris

    2013-10-01

    Tight junctions (TJs) of cells expressing simple epithelial polarity have been extensively studied, but less is known about TJs of cells expressing complex polarity. In this paper we analyzed, TJs of four different lines, that form bile canaliculi (BC) and express typical hepatocyte polarity; WIF-B9, 11-3, Can 3-1, Can 10. Striking differences were observed in claudin expression. None of the cell lines produced claudin-1. WIF-B9 and 11-3 expressed only claudin-2 while Can 3-1 and Can 10 expressed claudin-2,-3,-4,-5. TJs of these two classes of lines differed in their ultra-stucture, paracellular permeability, and robustness. Lines expressing a large claudin repertoire, especially Can 10, had complex and efficient TJs, that were maintained when cells were depleted in calcium. Inversely, TJs of WIF-B9 and 11-3 were leaky, permissive and dismantled by calcium depletion. Interestingly, we found that during the polarization process, TJ proteins expressed by all lines were sequentially settled in a specific order: first occludin, ZO-1 and cingulin, then JAM-A and ZO-2, finally claudin-2. Claudins expressed only in Can lines were also sequentially settled: claudin-3 was the first settled. Inhibition of claudin-3 expression delayed BC formation in Can10 and induced the expression of simple epithelial polarity. These results highlight the role of claudins in the settlement and the efficiency of TJs in lines expressing typical hepatocyte polarity. Can 10 seems to be the most promising of these lines because of its claudin repertoire near that of hepatocytes and its capacity to form extended tubular BC sealed by efficient TJs. PMID:24665408

  17. Solution-processed efficient CdTe nanocrystal/CBD-CdS hetero-junction solar cells with ZnO interlayer

    International Nuclear Information System (INIS)

    CdTe nanocrystal (NC)/CdS p–n hetero-junction solar cells with an ITO/ZnO-In/CdS/CdTe/MoOx/Ag-inverted structure were prepared by using a layer-by-layer solution process. The CdS thin films were prepared by chemical bath deposition on top of ITO/ZnO-In and were found to be very compact and pin-hole free in a large area, which insured high quality CdTe NCs thin-film formation upon it. The device performance was strongly related to the CdCl2 annealing temperature and annealing time. Devices exhibited power conversion efficiency (PCE) of 3.08 % following 400 °C CdCl2 annealing for 5 min, which was a good efficiency for solution processed CdTe/CdS NC-inverted solar cells. By carefully designing and optimizing the CdCl2-annealing conditions (370 °C CdCl2 annealing for about 15 min), the PCE of such devices showed a 21 % increase, in comparison to 400 °C CdCl2-annealing conditions, and reached a better PCE of 3.73 % while keeping a relatively high VOC of 0.49 V. This PCE value, to the best of our knowledge, is the highest PCE reported for solution processed CdTe–CdS NC solar cells. Moreover, the inverted solar cell device was very stable when kept under ambient conditions, less than 4 % degradation was observed in PCE after 40 days storage

  18. Relating specific connexin co-expression ratio to connexon composition and gap junction function.

    Science.gov (United States)

    Desplantez, T; Grikscheit, K; Thomas, N M; Peters, N S; Severs, N J; Dupont, E

    2015-12-01

    Cardiac connexin 43 (Cx43), Cx40 and Cx45 are co-expressed at distinct ratios in myocytes. This pattern is considered a key factor in regulating the gap junction channels composition, properties and function and remains poorly understood. This work aims to correlate gap junction function with the connexin composition of the channels at accurate ratios Cx43:Cx40 and Cx43:Cx45. Rat liver epithelial cells that endogenously express Cx43 were stably transfected to induce expression of accurate levels of Cx40 or Cx45 that may be present in various areas of the heart (e.g. atria and ventricular conduction system). Induction of Cx40 does not increase the amounts of junctional connexins (Cx43 and Cx40), whereas induction of Cx45 increases the amounts of junctional connexins (Cx43 and Cx45). Interestingly, the non-junctional fraction of Cx43 remains unaffected upon induction of Cx40 and Cx45. Co-immunoprecipitation studies show low level of Cx40/Cx43 heteromerisation and undetectable Cx45/Cx43 heteromerisation. Functional characterisation shows that induction of Cx40 and Cx45 decreases Lucifer Yellow transfer. Electrical coupling is decreased by Cx45 induction, whereas it is decreased at low induction of Cx40 and increased at high induction. These data indicate a fine regulation of the gap junction channel make-up in function of the type and the ratio of co-expressed Cxs that specifically regulates chemical and electrical coupling. This reflects specific gap junction function in regulating impulse propagation in the healthy heart, and a pro-arrhythmic potential of connexin remodelling in the diseased heart. PMID:26550940

  19. Clinico-pathological correlation of micronuclei in oral squamous cell carcinoma by exfoliative cytology

    OpenAIRE

    Palve Devendra; Tupkari Jagdish

    2008-01-01

    Oral squamous cell carcinoma accounts for 90% to 95% of all oral malignancies. Though its diagnosis seldom presents difficulty, it is the cancer staging and histopathological grading that are important to prognostication; and micronuclei are good prognostic indicators. Micronucleus frequencies in oral exfoliated cells stained with papanicolaou stain were counted and correlated with the histopathological grades and clinical stages of squamous cell carcinoma patients. They were al...

  20. Correlated Parameter Fit of Arrhenius Model for Thermal Denaturation of Proteins and Cells

    OpenAIRE

    Qin, Zhenpeng; Balasubramanian, Saravana Kumar; Wolkers, Willem F.; Pearce, John A.; Bischof, John C.

    2014-01-01

    Thermal denaturation of proteins is critical to cell injury, food science and other biomaterial processing. For example protein denaturation correlates strongly with cell death by heating, and is increasingly of interest in focal thermal therapies of cancer and other diseases at temperatures which often exceed 50 °C. The Arrhenius model is a simple yet widely used model for both protein denaturation and cell injury. To establish the utility of the Arrhenius model for protein denaturation at 5...