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Sample records for control cell sensitivity

  1. Organic photovoltaic cells with controlled polarization sensitivity

    SciTech Connect

    Awartani, Omar; O'Connor, Brendan T.; Kudenov, Michael W.

    2014-03-03

    In this study, we demonstrate linearly polarized organic photovoltaic cells with a well-controlled level of polarization sensitivity. The polarized devices were created through the application of a large uniaxial strain to the bulk heterojunction poly(3-hexylthiophene):Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) film and printing the plastically deformed active layer onto a PEDOT:PSS and indium tin oxide coated glass substrate. The P3HT:PCBM layer is processed such that it is able to accommodate high strains (over 100%) without fracture. After printing the strained films, thermal annealing is used to optimize solar cell performance while maintaining polarization sensitivity. A dichroic ratio and short circuit current ratio of ≈6.1 and ≈1.6 were achieved, respectively.

  2. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture.

    PubMed

    Klein, M; Pankiewicz, R; Zalas, M; Stampor, W

    2016-01-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism. PMID:27440452

  3. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture.

    PubMed

    Klein, M; Pankiewicz, R; Zalas, M; Stampor, W

    2016-07-21

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.

  4. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture

    NASA Astrophysics Data System (ADS)

    Klein, M.; Pankiewicz, R.; Zalas, M.; Stampor, W.

    2016-07-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.

  5. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture

    PubMed Central

    Klein, M.; Pankiewicz, R.; Zalas, M.; Stampor, W.

    2016-01-01

    The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism. PMID:27440452

  6. Decoy receptors block TRAIL sensitivity at a supracellular level: the role of stromal cells in controlling tumour TRAIL sensitivity.

    PubMed

    O'Leary, L; van der Sloot, A M; Reis, C R; Deegan, S; Ryan, A E; Dhami, S P S; Murillo, L S; Cool, R H; Correa de Sampaio, P; Thompson, K; Murphy, G; Quax, W J; Serrano, L; Samali, A; Szegezdi, E

    2016-03-10

    Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a death ligand cytokine known for its cytotoxic activity against malignantly transformed cells. TRAIL induces cell death through binding to death receptors DR4 and DR5. The inhibitory decoy receptors (DcR1 and DcR2) co-expressed with death receptor 4 (DR4)/DR5 on the same cell can block the transmission of the apoptotic signal. Here, we show that DcRs also regulate TRAIL sensitivity at a supracellular level and thus represent a mechanism by which the microenvironment can diminish tumour TRAIL sensitivity. Mathematical modelling and layered or spheroid stroma-extracellular matrix-tumour cultures were used to model the tumour microenvironment. By engineering TRAIL to escape binding by DcRs, we found that DcRs do not only act in a cell-autonomous or cis-regulatory manner, but also exert trans-cellular regulation originating from stromal cells and affect tumour cells, highlighting the potent inhibitory effect of DcRs in the tumour tissue and the necessity of selective targeting of the two death-inducing TRAIL receptors to maximise efficacy. PMID:26050621

  7. Control of Nanostructures and Interfaces of Metal Oxide Semiconductors for Quantum-Dots-Sensitized Solar Cells.

    PubMed

    Tian, Jianjun; Cao, Guozhong

    2015-05-21

    Nanostructured metal oxide semiconductors (MOS), such as TiO2 and ZnO, have been regarded as an attractive material for the quantum dots sensitized solar cells (QDSCs), owing to their large specific surface area for loading a large amount of quantum dots (QDs) and strong scattering effect for capturing a sufficient fraction of photons. However, the large surface area of such nanostructures also provides easy pathways for charge recombination, and surface defects and connections between adjacent nanoparticles may retard effective charge injection and charge transport, leading to a loss of power conversion efficiency. Introduction of the surface modification for MOS or QDs has been thought an effective approach to improve the performance of QDSC. In this paper, the recent advances in the control of nanostructures and interfaces in QDSCs and prospects for the further development with higher power conversion efficiency (PCE) have been discussed. PMID:26263261

  8. Orbital Topology Controlling Charge Injection in Quantum-Dot-Sensitized Solar Cells.

    PubMed

    Hansen, Thorsten; Žídek, Karel; Zheng, Kaibo; Abdellah, Mohamed; Chábera, Pavel; Persson, Petter; Pullerits, Tõnu

    2014-04-01

    Quantum-dot-sensitized solar cells are emerging as a promising development of dye-sensitized solar cells, where photostable semiconductor quantum dots replace molecular dyes. Upon photoexcitation of a quantum dot, an electron is transferred to a high-band-gap metal oxide. Swift electron transfer is crucial to ensure a high overall efficiency of the solar cell. Using femtosecond time-resolved spectroscopy, we find the rate of electron transfer to be surprisingly sensitive to the chemical structure of the linker molecules that attach the quantum dots to the metal oxide. A rectangular barrier model is unable to capture the observed variation. Applying bridge-mediated electron-transfer theory, we find that the electron-transfer rates depend on the topology of the frontier orbital of the molecular linker. This promises the capability of fine tuning the electron-transfer rates by rational design of the linker molecules.

  9. Efficiency enhancement in solid state dye sensitized solar cells by including inverse opals with controlled layer thicknesses

    NASA Astrophysics Data System (ADS)

    Zheng, Hanbin; Shah, Said Karim; Abbas, Mamatimin; Ly, Isabelle; Rivera, Thomas; Almeida, Rui M.; Hirsch, Lionel; Toupance, Thierry; Ravaine, Serge

    2016-09-01

    The photoconversion efficiency of dye sensitized solar cells can be enhanced by the incorporation of light management nanostructures such as photonic crystals. Here, we present a facile route to incorporate titania inverse opals into solid state dye sensitized solar cells and report photoconversion efficiency enhancements of up to 56% compared with a model system without the inverse opal. Our approach is based on the precise design of titania inverse opals with a predetermined thickness that can be controlled at the individual layer level. By choosing an inverse opal exhibiting a photonic bandgap which overlaps the absorption bands of the dye, our results show that there is an optimal thickness of the inverse opal structure for maximum efficiency enhancement of the cell. This is the first experimental proof that the thickness of a titania inverse opal plays a pivotal role in cell efficiency enhancement in solid state dye sensitized solar cells.

  10. The control of dendritic cell maturation by pH-sensitive polyion complex micelles.

    PubMed

    Boudier, Ariane; Aubert-Pouëssel, Anne; Louis-Plence, Pascale; Gérardin, Corine; Jorgensen, Christian; Devoisselle, Jean-Marie; Bégu, Sylvie

    2009-01-01

    Double-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell engineering to improve the delivery of therapeutic molecules in such immune cells. Polymethacrylic acid-b-polyethylene oxide (PMAA(2100)-b-POE(5000))/poly-L-lysine micelles were optimised and showed a hydrodynamic diameter of 30 nm with a peculiar core organised with hydrogen bonds as well as hydrophobic domains. The micelles proved high stability in physiological conditions (pH and ionic strength) and were also able to disassemble under acidic conditions mimicking acidic endolysosomes. The efficient endocytosis of the optimised micelles tested on bone marrow-derived dendritic cells was monitored by fluorescence-activated cell sorting and microscopy analysis. Finally, the micelle biocompatibility permitted a complete control of the dendritic cell-maturation process widening the therapeutical potential of such engineered dendritic cells for cancer vaccines as well as for immunomodulation in autoimmune diseases.

  11. Karyopherin alpha2: a control step of glucose-sensitive gene expression in hepatic cells.

    PubMed Central

    Guillemain, Ghislaine; Muñoz-Alonso, Maria J; Cassany, Aurélia; Loizeau, Martine; Faussat, Anne-Marie; Burnol, Anne-Françoise; Leturque, Armelle

    2002-01-01

    Glucose is required for an efficient expression of the glucose transporter GLUT2 and other genes. We have shown previously that the intracytoplasmic loop of GLUT2 can divert a signal, resulting in the stimulation of glucose-sensitive gene transcription. In the present study, by interaction with the GLUT2 loop, we have cloned the rat karyopherin alpha2, a receptor involved in nuclear import. The specificity of the binding was restricted to GLUT2, and not GLUT1 or GLUT4, and to karyopherin alpha2, not alpha1. When rendered irreversible by a cross-linking agent, this transitory interaction was detected in vivo in hepatocytes. A role for karyopherin alpha2 in the transcription of two glucose-sensitive genes was investigated by transfection of native and inactive green fluorescent protein-karyopherin alpha2 in GLUT2-expressing hepatoma cells. The amount of inactive karyopherin alpha2 receptor reduced, in a dose-dependent manner, the GLUT2 and liver pyruvate kinase mRNA levels by competition with endogenous active receptor. In contrast, the overexpression of karyopherin alpha2 did not significantly stimulate GLUT2 and liver pyruvate kinase mRNA accumulation in green fluorescent protein-sorted cells. The present study suggests that, in concert with glucose metabolism, karyopherin alpha2 transmits a signal to the nucleus to regulate glucose-sensitive gene expression. The transitory tethering of karyopherin alpha2 to GLUT2 at the plasma membrane might indicate that the receptor can load the cargo to be imported locally. PMID:11988093

  12. Accurate control of multishelled ZnO hollow microspheres for dye-sensitized solar cells with high efficiency.

    PubMed

    Dong, Zhenghong; Lai, Xiaoyong; Halpert, Jonathan E; Yang, Nailiang; Yi, Luoxin; Zhai, Jin; Wang, Dan; Tang, Zhiyong; Jiang, Lei

    2012-02-21

    A series of multishelled ZnO hollow microspheres with controlled shell number and inter-shell spacing have been successfully prepared by a simple carbonaceous microsphere templating method, whose large surface area and complex multishelled hollow structure enable them load sufficient dyes and multi-reflect the light for enhancing light harvesting and realize a high conversion efficiency of up to 5.6% when used in dye-sensitized solar cells. PMID:22266874

  13. Dye sensitized solar cells.

    PubMed

    Wei, Di

    2010-01-01

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO(2), ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

  14. Dye Sensitized Solar Cells

    PubMed Central

    Wei, Di

    2010-01-01

    Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency. Its efficiency is comparable to amorphous silicon solar cells but with a much lower cost. This review not only covers the fundamentals of DSSC but also the related cutting-edge research and its development for industrial applications. Most recent research topics on DSSC, for example, applications of nanostructured TiO2, ZnO electrodes, ionic liquid electrolytes, carbon nanotubes, graphene and solid state DSSC have all been included and discussed. PMID:20480003

  15. Single Cell Transcriptomics of Hypothalamic Warm Sensitive Neurons that Control Core Body Temperature and Fever Response

    PubMed Central

    Eberwine, James; Bartfai, Tamas

    2011-01-01

    We report on an ‘unbiased’ molecular characterization of individual, adult neurons, active in a central, anterior hypothalamic neuronal circuit, by establishing cDNA libraries from each individual, electrophysiologically identified warm sensitive neuron (WSN). The cDNA libraries were analyzed by Affymetrix microarray. The presence and frequency of cDNAs was confirmed and enhanced with Illumina sequencing of each single cell cDNA library. cDNAs encoding the GABA biosynthetic enzyme. GAD1 and of adrenomedullin, galanin, prodynorphin, somatostatin, and tachykinin were found in the WSNs. The functional cellular and in vivo studies on dozens of the more than 500 neurotransmitter -, hormone- receptors and ion channels, whose cDNA was identified and sequence confirmed, suggest little or no discrepancy between the transcriptional and functional data in WSNs; whenever agonists were available for a receptor whose cDNA was identified, a functional response was found.. Sequencing single neuron libraries permitted identification of rarely expressed receptors like the insulin receptor, adiponectin receptor2 and of receptor heterodimers; information that is lost when pooling cells leads to dilution of signals and mixing signals. Despite the common electrophysiological phenotype and uniform GAD1 expression, WSN- transcriptomes show heterogenity, suggesting strong epigenetic influence on the transcriptome. Our study suggests that it is well-worth interrogating the cDNA libraries of single neurons by sequencing and chipping. PMID:20970451

  16. MARCH1 regulates insulin sensitivity by controlling cell surface insulin receptor levels.

    PubMed

    Nagarajan, Arvindhan; Petersen, Max C; Nasiri, Ali R; Butrico, Gina; Fung, Annie; Ruan, Hai-Bin; Kursawe, Romy; Caprio, Sonia; Thibodeau, Jacques; Bourgeois-Daigneault, Marie-Claude; Sun, Lisha; Gao, Guangping; Bhanot, Sanjay; Jurczak, Michael J; Green, Michael R; Shulman, Gerald I; Wajapeyee, Narendra

    2016-01-01

    Insulin resistance is a key driver of type 2 diabetes (T2D) and is characterized by defective insulin receptor (INSR) signalling. Although surface INSR downregulation is a well-established contributor to insulin resistance, the underlying molecular mechanisms remain obscure. Here we show that the E3 ubiquitin ligase MARCH1 impairs cellular insulin action by degrading cell surface INSR. Using a large-scale RNA interference screen, we identify MARCH1 as a negative regulator of INSR signalling. March1 loss-of-function enhances, and March1 overexpression impairs, hepatic insulin sensitivity in mice. MARCH1 ubiquitinates INSR to decrease cell surface INSR levels, but unlike other INSR ubiquitin ligases, MARCH1 acts in the basal state rather than after insulin stimulation. Thus, MARCH1 may help set the basal gain of insulin signalling. MARCH1 expression is increased in white adipose tissue of obese humans, suggesting that MARCH1 contributes to the pathophysiology of T2D and could be a new therapeutic target. PMID:27577745

  17. MARCH1 regulates insulin sensitivity by controlling cell surface insulin receptor levels

    PubMed Central

    Nagarajan, Arvindhan; Petersen, Max C.; Nasiri, Ali R.; Butrico, Gina; Fung, Annie; Ruan, Hai-Bin; Kursawe, Romy; Caprio, Sonia; Thibodeau, Jacques; Bourgeois-Daigneault, Marie-Claude; Sun, Lisha; Gao, Guangping; Bhanot, Sanjay; Jurczak, Michael J.; Green, Michael R.; Shulman, Gerald I.; Wajapeyee, Narendra

    2016-01-01

    Insulin resistance is a key driver of type 2 diabetes (T2D) and is characterized by defective insulin receptor (INSR) signalling. Although surface INSR downregulation is a well-established contributor to insulin resistance, the underlying molecular mechanisms remain obscure. Here we show that the E3 ubiquitin ligase MARCH1 impairs cellular insulin action by degrading cell surface INSR. Using a large-scale RNA interference screen, we identify MARCH1 as a negative regulator of INSR signalling. March1 loss-of-function enhances, and March1 overexpression impairs, hepatic insulin sensitivity in mice. MARCH1 ubiquitinates INSR to decrease cell surface INSR levels, but unlike other INSR ubiquitin ligases, MARCH1 acts in the basal state rather than after insulin stimulation. Thus, MARCH1 may help set the basal gain of insulin signalling. MARCH1 expression is increased in white adipose tissue of obese humans, suggesting that MARCH1 contributes to the pathophysiology of T2D and could be a new therapeutic target. PMID:27577745

  18. Sensitive cells: enabling tools for static and dynamic control of microbial metabolic pathways.

    PubMed

    Cress, Brady F; Trantas, Emmanouil A; Ververidis, Filippos; Linhardt, Robert J; Koffas, Mattheos Ag

    2015-12-01

    Natural metabolic pathways are dynamically regulated at the transcriptional, translational, and protein levels. Despite this, traditional pathway engineering has relied on static control strategies to engender changes in metabolism, most likely due to ease of implementation and perceived predictability of design outcome. Increasingly in recent years, however, metabolic engineers have drawn inspiration from natural systems and have begun to harness dynamically controlled regulatory machinery to improve design of engineered microorganisms for production of specialty and commodity chemicals. Here, we review recent enabling technologies for engineering static control over pathway expression levels, and we discuss state-of-the-art dynamic control strategies that have yielded improved outcomes in the field of microbial metabolic engineering. Furthermore, we emphasize design of a novel class of genetically encoded controllers that will facilitate automatic, transient tuning of synthetic and endogenous pathways.

  19. Peanut shaped ZnO microstructures: controlled synthesis and nucleation growth toward low-cost dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Prabhu, M.; Mayandi, J.; Mariammal, R. N.; Vishnukanthan, V.; Pearce, J. M.; Soundararajan, N.; Ramachandran, K.

    2015-06-01

    This paper describes a simple, low-temperature and cost effective chemical precipitation method in aqueous media to synthesis uniformly distributed zinc oxide (ZnO) microstructures for the fabrication of dye-sensitized solar cells (DSSCs). The size and morphology of the ZnO microstructures are systematically controlled by adjusting the concentration of the precursors, zinc acetate dihydrate and ammonium hydroxide. X-ray diffraction (XRD) and scanning electron microscopy are used for the structural characterizations and photoluminescence and Fourier transform infrared spectroscopy are used to characterize the optical properties of the ZnO, respectively. The results reveal that ZnO crystallites exhibit hexagonal wurtzite structure with preferential orientation along c-axis. The effect of ammonia concentration on the crystallinity, morphology and optical properties of ZnO microstructures and the concomitant effect on the efficiency of DSSCs is also quantified. The peanut-shaped ZnO microstructure, which was found to increase DSSCs performance over other microstructure, is studied in detail in order to develop a formation mechanism. A sandwich type eosin yellow sensitized solar cell is prepared using peanut-shaped ZnO microstructures, which showed an efficiency of 0.37%. Ammonia was found to play a crucial role in the evolution of ZnO morphologies. These results are promising and provide a path towards low-cost high-performance DSSCs based on peanut-shaped ZnO microstructures and produced with only relatively simple wet chemistry synthesis.

  20. Inflammation Controls Sensitivity of Human and Mouse Intestinal Epithelial Cells to Galectin-1.

    PubMed

    Muglia, Cecilia I; Gobbi, Rodrigo Papa; Smaldini, Paola; Delgado, María Lucía Orsini; Candia, Martín; Zanuzzi, Carolina; Sambuelli, Alicia; Rocca, Andrés; Toscano, Marta A; Rabinovich, Gabriel A; Docena, Guillermo H

    2016-07-01

    Galectins play key roles in the inflammatory cascade. In this study, we aimed to analyze the effect of galectin-1 (Gal-1) in the function of intestinal epithelial cells (IECs) isolated from healthy and inflamed mucosa. IECs isolated from mice or patients with inflammatory bowel diseases (IBD) were incubated with different pro-inflammatory cytokines, and Gal-1 binding, secretion of homeostatic factors and viability were assessed. Experimental models of food allergy and colitis were used to evaluate the in vivo influence of inflammation on Gal-1 binding and modulation of IECs. We found an enhanced binding of Gal-1 to: (a) murine IECs exposed to IL-1β, TNF, and IL-13; (b) IECs from inflamed areas in intestinal tissue from IBD patients; (c) small bowel of allergic mice; and (d) colon from mice with experimental colitis. Our results showed that low concentrations of Gal-1 favored a tolerogenic micro-environment, whereas high concentrations of this lectin modulated viability of IECs through mechanisms involving activation of caspase-9 and modulation of Bcl-2 protein family members. Our results showed that, when added in the presence of diverse pro-inflammatory cytokines such as tumor necrosis factor (TNF), IL-13 and IL-5, Gal-1 differentially promoted the secretion of growth factors including thymic stromal lymphopoietin (TSLP), epidermal growth factor (EGF), IL-10, IL-25, and transforming growth factor (TGF-β1 ). In conclusion, we found an augmented binding of Gal-1 to IECs when exposed in vitro or in vivo to inflammatory stimuli, showing different effects depending on Gal-1 concentration. These findings highlight the importance of the inflammatory micro-environment of mucosal tissues in modulating IECs susceptibility to the immunoregulatory lectin Gal-1 and its role in epithelial cell homeostasis.

  1. Size-controlled anatase titania single crystals with octahedron-like morphology for dye-sensitized solar cells.

    PubMed

    Shiu, Jia-Wei; Lan, Chi-Ming; Chang, Yu-Cheng; Wu, Hui-Ping; Huang, Wei-Kai; Diau, Eric Wei-Guang

    2012-12-21

    A simple hydrothermal method with titanium tetraisopropoxide (TTIP) as a precursor and triethanolamine (TEOA) as a chelating agent enabled growth in the presence of a base (diethylamine, DEA) of anatase titania nanocrystals (HD1-HD5) of controlled size. DEA played a key role to expedite this growth, for which a biphasic crystal growth mechanism is proposed. The produced single crystals of titania show octahedron-like morphology with sizes in a broad range of 30-400 nm; a typical, extra large, octahedral single crystal (HD5) of length 410 nm and width 260 nm was obtained after repeating a sequential hydrothermal treatment using HD3 and then HD4 as a seed crystal. The nanocrystals of size ~30 nm (HD1) and ~300 nm (HD5) served as active layer and scattering layer, respectively, to fabricate N719-sensitized solar cells. These HD devices showed greater V(OC) than devices of conventional nanoparticle (NP) type; the overall device performance of HD attained an efficiency of 10.2% power conversion at a total film thickness of 28 μm, which is superior to that of a NP-based reference device (η = 9.6%) optimized at a total film thickness of 18-20 μm. According to results obtained from transient photoelectric and charge extraction measurements, this superior performance of HD devices relative to their NP counterparts is due to the more rapid electron transport and greater TiO(2) potential.

  2. Size-controlled anatase titania single crystals with octahedron-like morphology for dye-sensitized solar cells.

    PubMed

    Shiu, Jia-Wei; Lan, Chi-Ming; Chang, Yu-Cheng; Wu, Hui-Ping; Huang, Wei-Kai; Diau, Eric Wei-Guang

    2012-12-21

    A simple hydrothermal method with titanium tetraisopropoxide (TTIP) as a precursor and triethanolamine (TEOA) as a chelating agent enabled growth in the presence of a base (diethylamine, DEA) of anatase titania nanocrystals (HD1-HD5) of controlled size. DEA played a key role to expedite this growth, for which a biphasic crystal growth mechanism is proposed. The produced single crystals of titania show octahedron-like morphology with sizes in a broad range of 30-400 nm; a typical, extra large, octahedral single crystal (HD5) of length 410 nm and width 260 nm was obtained after repeating a sequential hydrothermal treatment using HD3 and then HD4 as a seed crystal. The nanocrystals of size ~30 nm (HD1) and ~300 nm (HD5) served as active layer and scattering layer, respectively, to fabricate N719-sensitized solar cells. These HD devices showed greater V(OC) than devices of conventional nanoparticle (NP) type; the overall device performance of HD attained an efficiency of 10.2% power conversion at a total film thickness of 28 μm, which is superior to that of a NP-based reference device (η = 9.6%) optimized at a total film thickness of 18-20 μm. According to results obtained from transient photoelectric and charge extraction measurements, this superior performance of HD devices relative to their NP counterparts is due to the more rapid electron transport and greater TiO(2) potential. PMID:23116194

  3. Ultrathin FeSe2 nanosheets: controlled synthesis and application as a heterogeneous catalyst in dye-sensitized solar cells.

    PubMed

    Huang, Shoushuang; He, Qingquan; Chen, Wenlong; Qiao, Qiquan; Zai, Jiantao; Qian, Xuefeng

    2015-03-01

    Two-dimensional (2D) semiconducting nanosheets have emerged as an important field of materials, owing to their unique properties and potential applications in areas ranging from electronics to catalysis. However, the controlled synthesis of ultrathin 2D nanosheets remains a great challenge, due to the lack of an intrinsic driving force for anisotropic growth. High-quality ultrathin 2D FeSe2 nanosheets with average thickness below 7 nm have been synthesized on large scale by a facile solution method, and a formation mechanism has been proposed. Due to their favorable structural features, the as-synthesized ultrathin FeSe2 nanosheets exhibit excellent electrocatalytic activity for the reduction of triiodide to iodide and low charge-transfer resistance at the electrolyte-electrode interface in dye-sensitized solar cells (DSSCs). The DSSCs with FeSe2 nanosheets as counter electrode material achieve a high power conversion efficiency of 7.53% under a simulated solar illumination of 100 mW cm(-2) (AM 1.5), which is comparable with that of Pt-based devices (7.47%).

  4. Cell Cycle Control and Adhesion Molecule Expression in Cells of the Immune System are Sensitive to Altered Gravity

    NASA Astrophysics Data System (ADS)

    Ullrich, O.; Paulsen, K.; Thiel, C.; Herrmann, K.; Sang, C.; Han, G.; Hemmersbach, R.; von der Wiesche, M.; Kroll, H.; Zhuang, F.; Grote, K. H.; Cogoli, A.; Zipp, F.; Engelmann, F.

    2008-06-01

    Life on earth developed in the presence and under the constant influence of gravity. Thus, it is a fundamental biological question, whether gravity is required for cellular functions and signal transduction in mammalian cells. Since the first Spacelab-Mission 20 years ago, it is known that activation and function of T lymphocytes is severely suppressed in microgravity, but the underlying molecular mechanisms are not elucidated. Experiments have been performed using ground-based facilities such as fast-rotating clinostat and hyper-g-centrifuges, and real microgravity provided by parabolic flights. We found that 1.) cells of the immune system responded cell type specifically to altered gravity, 2.) microgravity induced a multitude of initial alterations in signal transduction, whereas 3.) hypergravity of 1.8g did not induce any changes of the pathways tested, and that 4.) most of the initially altered pathways in microgravity adapted to "normal" levels within 15min. However, some pathways remained altered and could explain cell cycle arrest of T lymphocytes as observed in several long-term space experiments.

  5. Dye Sensitized Tandem Photovoltaic Cells

    SciTech Connect

    Barber, Greg D.

    2009-12-21

    This work provided a new way to look at photoelectrochemical cells and their performance. Although thought of as low efficiency, a the internal efficiency of a 9% global efficiency dye sensitized solar cell is approximately equal to an 18% efficient silicon cell when each is compared to their useful spectral range. Other work undertaken with this contract also reported the first growth oriented titania and perovskite columns on a transparent conducting oxide. Other work has shown than significant performance enhancement in the performance of dye sensitized solar cells can be obtained through the use of coupling inverse opal photonic crystals to the nanocrystalline dye sensitized solar cell. Lastly, a quick efficient method was developed to bond titanium foils to transparent conducting oxide substrates for anodization.

  6. Controllable synthesis of ZnO nanograss with different morphologies and enhanced performance in dye-sensitized solar cells

    SciTech Connect

    Zhu Shibu; Chen Xiangnan; Zuo Feibiao; Jiang Man; Zhou Zuowan; Hui, David

    2013-01-15

    A series of ZnO nanograss films grown on fluorine-doped tin oxide coated glass substrates were synthesized via hydrothermal method by using polyethyleneimine (PEI) as adjusting agent. The films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). It was found that the PEI not only affected the aspect ratios of ZnO nanograss but also changed the geometrical shape of ZnO nanograss. A possible mechanism based on PEI adsorbed on the non-polar facets of ZnO that governed the growth rate of different directions were proposed to elucidate the effect of PEI on morphology of ZnO. The ZnO nanograss films were applied to dye-sensitized solar cells (DSSCs). The results showed that the photocurrent density significantly enhanced, and the power conversion efficiency increased by 55% based on ZnO nanograss synthesized in a growth solution containing 7 mmol/L PEI, resulting from the dye loading properties related to the different morphologies. - Graphical abstract: Effect of PEI on ZnO nanograss: controlling the aspect ratio and morphology of ZnO and enhancing their photovoltaic performance. Highlights: Black-Right-Pointing-Pointer ZnO nanograss with different aspect ratios were synthesized by adjusting PEI content. Black-Right-Pointing-Pointer PEI affects both on the aspect ratios and geometrical shapes of ZnO nanograss. Black-Right-Pointing-Pointer ZnO nanograss with high aspect ratio and needle-like tip was advantageous for improved photovoltaic conversion performance.

  7. A programmable synthetic lineage-control network that differentiates human IPSCs into glucose-sensitive insulin-secreting beta-like cells.

    PubMed

    Saxena, Pratik; Heng, Boon Chin; Bai, Peng; Folcher, Marc; Zulewski, Henryk; Fussenegger, Martin

    2016-01-01

    Synthetic biology has advanced the design of standardized transcription control devices that programme cellular behaviour. By coupling synthetic signalling cascade- and transcription factor-based gene switches with reverse and differential sensitivity to the licensed food additive vanillic acid, we designed a synthetic lineage-control network combining vanillic acid-triggered mutually exclusive expression switches for the transcription factors Ngn3 (neurogenin 3; OFF-ON-OFF) and Pdx1 (pancreatic and duodenal homeobox 1; ON-OFF-ON) with the concomitant induction of MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homologue A; OFF-ON). This designer network consisting of different network topologies orchestrating the timely control of transgenic and genomic Ngn3, Pdx1 and MafA variants is able to programme human induced pluripotent stem cells (hIPSCs)-derived pancreatic progenitor cells into glucose-sensitive insulin-secreting beta-like cells, whose glucose-stimulated insulin-release dynamics are comparable to human pancreatic islets. Synthetic lineage-control networks may provide the missing link to genetically programme somatic cells into autologous cell phenotypes for regenerative medicine. PMID:27063289

  8. A programmable synthetic lineage-control network that differentiates human IPSCs into glucose-sensitive insulin-secreting beta-like cells

    PubMed Central

    Saxena, Pratik; Heng, Boon Chin; Bai, Peng; Folcher, Marc; Zulewski, Henryk; Fussenegger, Martin

    2016-01-01

    Synthetic biology has advanced the design of standardized transcription control devices that programme cellular behaviour. By coupling synthetic signalling cascade- and transcription factor-based gene switches with reverse and differential sensitivity to the licensed food additive vanillic acid, we designed a synthetic lineage-control network combining vanillic acid-triggered mutually exclusive expression switches for the transcription factors Ngn3 (neurogenin 3; OFF-ON-OFF) and Pdx1 (pancreatic and duodenal homeobox 1; ON-OFF-ON) with the concomitant induction of MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homologue A; OFF-ON). This designer network consisting of different network topologies orchestrating the timely control of transgenic and genomic Ngn3, Pdx1 and MafA variants is able to programme human induced pluripotent stem cells (hIPSCs)-derived pancreatic progenitor cells into glucose-sensitive insulin-secreting beta-like cells, whose glucose-stimulated insulin-release dynamics are comparable to human pancreatic islets. Synthetic lineage-control networks may provide the missing link to genetically programme somatic cells into autologous cell phenotypes for regenerative medicine. PMID:27063289

  9. Controllable preparation of TiO2 nanowire arrays on titanium mesh for flexible dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Wenwu; Lu, Hui; Zhang, Mei; Guo, Min

    2015-08-01

    TiO2 nanowire arrays (NWAs) with an average diameter of 80 nm have been successfully synthesized on titanium (Ti) mesh substrates via hydrothermal method. The effects of preparing conditions such as concentration of NaOH solution, reaction time, and hydrothermal temperature on the growth of TiO2 nanoarrays and its related photovoltaic properties were systematically investigated by scanning electron microscopy, X-ray diffraction, and photovoltaic properties test. The growth mechanism of the Ti mesh-supported TiO2 nanostructures was discussed in detail. Moreover, a parametric study was performed to determine the optimized temperature and time of the dye sensitized process for the flexible dye-sensitized solar cell (DSSC). It is demonstrated that hydrothermal parameters had obvious influence on the morphology and growth density of the as-prepared TiO2 nanoarrays. In addition, the performance of the flexible DSSC depended strongly on the sensitization temperature and time. By utilizing Ti mesh-supported TiO2 NWAs (with a length of about 14 μm) as a photoanode, the flexible DSSC with a short circuit current density of 10.49 mA cm-2, an open-circuit voltage of 0.69 V, and an overall power conversion efficiency of 3.42% was achieved.

  10. Methionine-sensitive glycolysis in transformed cells.

    PubMed

    Boerner, P; Racker, E

    1985-10-01

    Glycolysis in several tumor cell lines grown in tissue culture was inhibited by methionine. Kirsten murine sarcoma virus-transformed rat kidney cells (K-NRK) were inhibited 60-75% by 10 mM methionine, whereas normal rat kidney (NRK-49F) cells showed little or no inhibition. Inhibition of glycolysis in K-NRK cells was manifest 2-4 hr after exposure to the amino acid. Glycolysis in a chemically transformed cell line of Madin-Darby canine kidney cells was also sensitive to methionine, but maximal inhibition (75%) required 18-24 hr of incubation with the amino acid. Under the same conditions glycolysis in the nontransformed canine cells was less than 20% inhibited by methionine. In Ehrlich ascites tumor cells grown in tissue culture, 10 mM methionine inhibited glycolysis by about 50%. Inhibition of glycolysis, even by 50 mM methionine, was rapidly reversible. Within 2 hr after removal of methionine the rate of glycolytic activity was restored to that observed in control cells. Furthermore, inhibition by methionine required a minimum level (7%) of serum in the growth medium and inhibition was not sensitive to cycloheximide. Only amino acids that are transported by system A (including the nonmetabolized analogue methylaminoisobutyric acid) specifically inhibited glycolysis in tumor cells. The only exception was phenylalanine, which was toxic to both transformed and normal cell lines.

  11. A synthetic cGMP-sensitive gene switch providing Viagra(®)-controlled gene expression in mammalian cells and mice.

    PubMed

    Kim, Taeuk; Folcher, Marc; Charpin-El Hamri, Ghislaine; Fussenegger, Martin

    2015-05-01

    Cyclic guanosine monophosphate (cGMP) is a universal second messenger that is synthesized from guanosine triphosphate (GTP) by guanylyl cyclases (GCs) and hydrolyzed into guanosine monophosphate (GMP) by phosphodiesterases (PDEs). Small-molecule drugs that induce high cGMP levels in specialized tissues by boosting GC activity or inhibiting PDE activity have become the predominant treatment strategy for a wide range of medical conditions, including congestive heart failure, pulmonary hypertension, atherosclerosis-based claudication and erectile dysfunction. By fusing the cGMP receptor protein (CRP) of Rhodospirillum centenum to the Herpes simplex-derived transactivation domain VP16, we created a novel synthetic mammalian cGMP-sensing transcription factor (GTA) that activates synthetic promoters (PGTA) containing newly identified GTA-specific operator sites in a concentration-dependent manner. In cell lines expressing endogenous natriuretic peptide receptor A (NPR-A) (HeLa), GTA/PGTA-driven transgene expression was induced by B-type natriuretic peptide (BNP; Nesiritide(®)) in a concentration-dependent manner, which activated NPR-A׳s intracellular GC domain and triggered a corresponding cGMP surge. Ectopic expression of NPR-A in NPR-A-negative cell lines (HEK-293T) produced high cGMP levels and mediated maximum GTA/PGTA-driven transgene expression, which was suppressed by co-expression of PDEs (PDE-3A, PDE-5A and PDE-9A) and was re-triggered by the corresponding PDE inhibitor drugs (Pletal(®), Perfan(®), Primacor(®) (PDE-3A), Viagra(®), Levitra(®), Cialis(®) (PDE-5A) and BAY73-6691 (PDE-9A)). Mice implanted with microencapsulated designer cells co-expressing the GTA/PGTA device with NPR-A and PDE-5A showed control of blood SEAP levels through administration of sildenafil (Viagra(®)). Designer cells engineered for PDE inhibitor-modulated transgene expression may provide a cell-based PDE-targeting drug discovery platform and enable drug-adjusted gene- and cell

  12. Control of the recombination rate by changing the polarity of the electrolyte in dye-sensitized solar cells.

    PubMed

    Idigoras, Jesús; Tena-Zaera, Ramón; Anta, Juan A

    2014-10-21

    Recombination in Dye-sensitized Solar Cells (DSCs) is an electron transfer process critical for high efficiency. The chemical nature of the electron acceptor is known to have an important impact on recombination and, hence, limits the choice of hole conductors in DSCs and related solar cells. In this respect, Room Temperature Ionic liquids (RTILs) have been recognized as an alternative to volatile organic solvents due to their negligible vapor pressure, which offers the chance for long-term stability. However, RTIL-based electrolytes lead to lower performance, a feature that has been attributed to the high viscosity of ionic liquids and the mass-transport limitation associated with it. In this work we show that the origin of the lower performance is also related to an increase in the recombination loss due to the polar nature of the RTIL and the influence of the reorganization energy of the electron acceptor in a polar environment. To investigate this chemical effect, different mixing ratios of RTILs and an organic solvent (acetonitrile) have been considered. The fabricated devices have been characterized by small-perturbation techniques (Impedance Electrochemical Spectroscopy and Intensity-Modulated Photovoltage and Photocurrent Spectroscopies) and Open-Circuit Voltage Decay measurements, which have been used to extract electron lifetimes at different applied voltages. Two different ruthenium dyes (hydrophilic N719 and hydrophobic Z907) and two different cations in the RTIL (imidazolium- and pyrrolidinium-based) have been considered. The results obtained show that for pure ionic liquids the lifetime-voltage curve is exponential, which is a signature of large reorganization energies for electron transfer. In contrast, pure acetonitrile exhibits a non-exponential behavior, which is consistent with relatively low reorganization energy. Interestingly, and as a general rule, we find that recombination is faster in systems with higher reorganization energies. This is

  13. Control of the recombination rate by changing the polarity of the electrolyte in dye-sensitized solar cells.

    PubMed

    Idigoras, Jesús; Tena-Zaera, Ramón; Anta, Juan A

    2014-10-21

    Recombination in Dye-sensitized Solar Cells (DSCs) is an electron transfer process critical for high efficiency. The chemical nature of the electron acceptor is known to have an important impact on recombination and, hence, limits the choice of hole conductors in DSCs and related solar cells. In this respect, Room Temperature Ionic liquids (RTILs) have been recognized as an alternative to volatile organic solvents due to their negligible vapor pressure, which offers the chance for long-term stability. However, RTIL-based electrolytes lead to lower performance, a feature that has been attributed to the high viscosity of ionic liquids and the mass-transport limitation associated with it. In this work we show that the origin of the lower performance is also related to an increase in the recombination loss due to the polar nature of the RTIL and the influence of the reorganization energy of the electron acceptor in a polar environment. To investigate this chemical effect, different mixing ratios of RTILs and an organic solvent (acetonitrile) have been considered. The fabricated devices have been characterized by small-perturbation techniques (Impedance Electrochemical Spectroscopy and Intensity-Modulated Photovoltage and Photocurrent Spectroscopies) and Open-Circuit Voltage Decay measurements, which have been used to extract electron lifetimes at different applied voltages. Two different ruthenium dyes (hydrophilic N719 and hydrophobic Z907) and two different cations in the RTIL (imidazolium- and pyrrolidinium-based) have been considered. The results obtained show that for pure ionic liquids the lifetime-voltage curve is exponential, which is a signature of large reorganization energies for electron transfer. In contrast, pure acetonitrile exhibits a non-exponential behavior, which is consistent with relatively low reorganization energy. Interestingly, and as a general rule, we find that recombination is faster in systems with higher reorganization energies. This is

  14. Mitochondrial E3 ubiquitin ligase MARCH5 controls mitochondrial fission and cell sensitivity to stress-induced apoptosis through regulation of MiD49 protein

    PubMed Central

    Xu, Shan; Cherok, Edward; Das, Shweta; Li, Sunan; Roelofs, Brian A.; Ge, Shealinna X.; Polster, Brian M.; Boyman, Liron; Lederer, W. Jonathan; Wang, Chunxin; Karbowski, Mariusz

    2016-01-01

    Ubiquitin- and proteasome-dependent outer mitochondrial membrane (OMM)-associated degradation (OMMAD) is critical for mitochondrial and cellular homeostasis. However, the scope and molecular mechanisms of the OMMAD pathways are still not well understood. We report that the OMM-associated E3 ubiquitin ligase MARCH5 controls dynamin-related protein 1 (Drp1)-dependent mitochondrial fission and cell sensitivity to stress-induced apoptosis. MARCH5 knockout selectively inhibited ubiquitination and proteasomal degradation of MiD49, a mitochondrial receptor of Drp1, and consequently led to mitochondrial fragmentation. Mitochondrial fragmentation in MARCH5−/− cells was not associated with inhibition of mitochondrial fusion or bioenergetic defects, supporting the possibility that MARCH5 is a negative regulator of mitochondrial fission. Both MARCH5 re-expression and MiD49 knockout in MARCH5−/− cells reversed mitochondrial fragmentation and reduced sensitivity to stress-induced apoptosis. These findings and data showing MARCH5-dependent degradation of MiD49 upon stress support the possibility that MARCH5 regulation of MiD49 is a novel mechanism controlling mitochondrial fission and, consequently, the cellular response to stress. PMID:26564796

  15. Dye-sensitized solar cells

    DOEpatents

    Skotheim, Terje A. [Berkeley, CA

    1980-03-04

    A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

  16. Dye-sensitized solar cells

    DOEpatents

    Skotheim, T.A.

    1980-03-04

    A low-cost dye-sensitized Schottky barrier solar cell is comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent. 3 figs.

  17. A cyclophosphamide-sensitive cell compartment is essential for homologous protection conferred by licensed vaccines for the control of avian pathogenic Escherichia coli in chickens.

    PubMed

    Sadeyen, Jean-Rémy; Kaiser, Pete; Stevens, Mark P; Dziva, Francis

    2015-07-17

    Avian pathogenic Escherichia coli (APEC) exert substantial economic costs on poultry producers worldwide. Vaccination is an attractive method of control, but the immunological basis of protection is poorly understood. Here, we examine the effect of intramuscular injection of cyclophosphamide or saline on homologous protection induced by licensed inactivated or live-attenuated APEC O78 vaccines in chickens. In saline-treated birds, both vaccines induced significant APEC-specific IgY and protection against homologous challenge, as evidenced by enumeration of tissue-associated bacteria and analysis of pathology. In cyclophosphamide-treated birds, B cells were severely depleted whereas percentages of circulating CD4- and CD8-positive T cells were normal as detected by flow cytometry. Further, such birds did not produce APEC-specific IgY and were as susceptible to challenge as age-matched unvaccinated controls. The data indicate that homologous protection conferred by licensed APEC vaccines strictly requires a cyclophosphamide-sensitive cell population that includes B cells. PMID:26087298

  18. Spectral sensitization of nanocrystalline solar cells

    DOEpatents

    Spitler, Mark T.; Ehret, Anne; Stuhl, Louis S.

    2002-01-01

    This invention relates to dye sensitized polycrystalline photoelectrochemical solar cells for use in energy transduction from light to electricity. It concerns the utility of highly absorbing organic chromophores as sensitizers in such cells and the degree to which they may be utilized alone and in combination to produce an efficient photoelectrochemical cell, e.g., a regenerative solar cell.

  19. Controlling the texture and crystallinity of evaporated lead phthalocyanine thin films for near-infrared sensitive solar cells.

    PubMed

    Vasseur, Karolien; Broch, Katharina; Ayzner, Alexander L; Rand, Barry P; Cheyns, David; Frank, Christian; Schreiber, Frank; Toney, Michael F; Froyen, Ludo; Heremans, Paul

    2013-09-11

    To achieve organic solar cells with a broadened spectral absorption, we aim to promote the growth of the near-infrared (NIR)-active polymorph of lead phthalocyanine (PbPc) on a relevant electrode for solar cell applications. We studied the effect of different substrate modification layers on PbPc thin film structure as a function of thickness and deposition rate (rdep). We characterized crystallinity and orientation by grazing incidence X-ray diffraction (GIXD) and in situ X-ray reflectivity (XRR) and correlated these data to the performance of bilayer solar cells. When deposited onto a self-assembled monolayer (SAM) or a molybdenum oxide (MoO3) buffer layer, the crystallinity of the PbPc films improves with thickness. The transition from a partially crystalline layer close to the substrate to a more crystalline film with a higher content of the NIR-active phase is enhanced at low rdep, thereby leading to solar cells that exhibit a higher maximum in short circuit current density (JSC) for thinner donor layers. The insertion of a CuI layer induces the formation of strongly textured, crystalline PbPc layers with a vertically homogeneous structure. Solar cells based on these templated donor layers show a variation of JSC with thickness that is independent of rdep. Consequently, without decreasing rdep we could achieve JSC=10 mA/cm2, yielding a bilayer solar cell with a peak external quantum efficiency (EQE) of 35% at 900 nm, and an overall power conversion efficiency (PCE) of 2.9%.

  20. In-situ microfluidic controlled, low temperature hydrothermal growth of nanoflakes for dye-sensitized solar cells

    PubMed Central

    Zhao, Chao; Zhang, Jia; Hu, Yue; Robertson, Neil; Hu, Ping An; Child, David; Gibson, Desmond; Fu, Yong Qing

    2015-01-01

    In this paper, an in-situ microfluidic control unit (MCU) was designed and applied in a hydrothermal synthesis process, which provides an easy way to localize liquid-phase reaction and realize selective synthesis and direct growth of nanostructures as well as their morphology, all in a low-temperature and atmospheric environment. The morphology was controlled through controlling the amount of additivities using the MCU. This achieved a facile fabrication of Al doped ZnO (AZO) nanoflakes vertically grown on flexible polymer substrates with enhanced light scattering and dye loading capabilities. Flexible DSSCs with a significant enhancement (410% compare to ZnO NRs based devices) in power conversion efficiency were obtained using AZO nanoflake photoanodes of 6 μm thick, due to the enhancement in electron mobility and reduction in recombination. This hydrothermal synthesis using the in-situ MCU provides an efficient and scalable technique to synthesize controllable nanostructures with characteristics of easy set-up, low energy consumption and low cost. PMID:26631685

  1. In-situ microfluidic controlled, low temperature hydrothermal growth of nanoflakes for dye-sensitized solar cells.

    PubMed

    Zhao, Chao; Zhang, Jia; Hu, Yue; Robertson, Neil; Hu, Ping An; Child, David; Gibson, Desmond; Fu, Yong Qing

    2015-01-01

    In this paper, an in-situ microfluidic control unit (MCU) was designed and applied in a hydrothermal synthesis process, which provides an easy way to localize liquid-phase reaction and realize selective synthesis and direct growth of nanostructures as well as their morphology, all in a low-temperature and atmospheric environment. The morphology was controlled through controlling the amount of additivities using the MCU. This achieved a facile fabrication of Al doped ZnO (AZO) nanoflakes vertically grown on flexible polymer substrates with enhanced light scattering and dye loading capabilities. Flexible DSSCs with a significant enhancement (410% compare to ZnO NRs based devices) in power conversion efficiency were obtained using AZO nanoflake photoanodes of 6 μm thick, due to the enhancement in electron mobility and reduction in recombination. This hydrothermal synthesis using the in-situ MCU provides an efficient and scalable technique to synthesize controllable nanostructures with characteristics of easy set-up, low energy consumption and low cost. PMID:26631685

  2. In-situ microfluidic controlled, low temperature hydrothermal growth of nanoflakes for dye-sensitized solar cells.

    PubMed

    Zhao, Chao; Zhang, Jia; Hu, Yue; Robertson, Neil; Hu, Ping An; Child, David; Gibson, Desmond; Fu, Yong Qing

    2015-12-03

    In this paper, an in-situ microfluidic control unit (MCU) was designed and applied in a hydrothermal synthesis process, which provides an easy way to localize liquid-phase reaction and realize selective synthesis and direct growth of nanostructures as well as their morphology, all in a low-temperature and atmospheric environment. The morphology was controlled through controlling the amount of additivities using the MCU. This achieved a facile fabrication of Al doped ZnO (AZO) nanoflakes vertically grown on flexible polymer substrates with enhanced light scattering and dye loading capabilities. Flexible DSSCs with a significant enhancement (410% compare to ZnO NRs based devices) in power conversion efficiency were obtained using AZO nanoflake photoanodes of 6 μm thick, due to the enhancement in electron mobility and reduction in recombination. This hydrothermal synthesis using the in-situ MCU provides an efficient and scalable technique to synthesize controllable nanostructures with characteristics of easy set-up, low energy consumption and low cost.

  3. Risk-Sensitivity in Sensorimotor Control

    PubMed Central

    Braun, Daniel A.; Nagengast, Arne J.; Wolpert, Daniel M.

    2011-01-01

    Recent advances in theoretical neuroscience suggest that motor control can be considered as a continuous decision-making process in which uncertainty plays a key role. Decision-makers can be risk-sensitive with respect to this uncertainty in that they may not only consider the average payoff of an outcome, but also consider the variability of the payoffs. Although such risk-sensitivity is a well-established phenomenon in psychology and economics, it has been much less studied in motor control. In fact, leading theories of motor control, such as optimal feedback control, assume that motor behaviors can be explained as the optimization of a given expected payoff or cost. Here we review evidence that humans exhibit risk-sensitivity in their motor behaviors, thereby demonstrating sensitivity to the variability of “motor costs.” Furthermore, we discuss how risk-sensitivity can be incorporated into optimal feedback control models of motor control. We conclude that risk-sensitivity is an important concept in understanding individual motor behavior under uncertainty. PMID:21283556

  4. Dye-sensitized solar cells based on purple corn sensitizers

    NASA Astrophysics Data System (ADS)

    Phinjaturus, Kawin; Maiaugree, Wasan; Suriharn, Bhalang; Pimanpaeng, Samuk; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan

    2016-09-01

    Natural dye extracted from husk, cob and silk of purple corn, were used for the first time as photosensitizers in dye sensitized solar cells (DSSCs). The dye sensitized solar cells fabrication process has been optimized in terms of solvent extraction. The resulting maximal efficiency of 1.06% was obtained from purple corn husk extracted by acetone. The ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and incident photon-to-current efficiency (IPCE) were employed to characterize the natural dye and the DSSCs.

  5. Metal-Free Sensitizers for Dye-Sensitized Solar Cells.

    PubMed

    Chaurasia, Sumit; Lin, Jiann T

    2016-06-01

    This review focuses on our work on metal-free sensitizers for dye-sensitized solar cells (DSSCs). Sensitizers based on D-A'-π-A architecture (D is a donor, A is an acceptor, A' is an electron-deficient entity) exhibit better light harvesting than D-π-A-type sensitizers. However, appropriate molecular design is needed to avoid excessive aggregation of negative charge at the electron-deficient entity upon photoexcitation. Rigidified aromatics, including aromatic segments comprising fused electron-excessive and -deficient units in the spacer, allow effective electronic communication, and good photoinduced charge transfer leads to excellent cell performance. Sensitizers with two anchors/acceptors, D(-π-A)2 , can more efficiently harvest light, inject electrons, and suppress dark current compared with congeners with a single anchor. Appropriate incorporation of heteroaromatic units in the spacer is beneficial to DSSC performance. High-performance, aqueous-based DSSCs can be achieved with a dual redox couple comprising imidazolium iodide and 2,2,6,6-tetramethylpiperidin-N-oxyl, and/or using dyes of improved wettability through the incorporation of a triethylene oxide methyl ether chain. PMID:27114164

  6. Cisplatin sensitivity and thermochemosensitisation in thermotolerant cDDP-sensitive and -resistant cell lines.

    PubMed

    Hettinga, J V; Lemstra, W; Konings, A W; Kampinga, H H

    1995-03-01

    Development of thermotolerance is an important phenomenon that must be considered when thermochemotherapy with multiple heat treatments is used clinically. To study the effect of thermotolerance on cellular cisplatin (cDDP) sensitivity at 37 degrees C and 43 degrees C in cell lines with different cDDP sensitivities, two Ehrlich ascites tumour cell lines (one with high cDDP sensitivity and one with in vitro acquired cDDP resistance) were used. The results indicate that in both cell lines the state of thermotolerance per se did not affect the cDDP sensitivity at 37 degrees C. Thus, general elevations in 'all' heat shock protein levels as found in thermotolerant cells apparently do not influence cDDP sensitivity to a considerable extent. The sensitising effect of a (second) heat treatment given simultaneously with a cDDP treatment was less in thermotolerant cells. Thermal enhancement ratios (TERs) at the 10% survival level for heat doses of 43 degrees C for 30 min or 43 degrees C for 60 min were reduced by a factor of 1.6 and 2.1 in cDDP-resistant and -sensitive thermotolerant cells respectively, as compared with control cells. Thus, protection against heat damage in thermotolerant cells seems to be paralleled by diminished thermal chemosensitisation. Although the effect of thermotolerance on the cDDP-sensitising effect was less pronounced in the resistant cells, a modifying effect on the resistance factor was not achieved.

  7. Gene sensitizes cancer cells to chemotherapy drugs

    Cancer.gov

    NCI scientists have found that a gene, Schlafen-11 (SLFN11), sensitizes cells to substances known to cause irreparable damage to DNA.  As part of their study, the researchers used a repository of 60 cell types to identify predictors of cancer cell respons

  8. Attainability analysis in the stochastic sensitivity control

    NASA Astrophysics Data System (ADS)

    Bashkirtseva, Irina

    2015-02-01

    For nonlinear dynamic stochastic control system, we construct a feedback regulator that stabilises an equilibrium and synthesises a required dispersion of random states around this equilibrium. Our approach is based on the stochastic sensitivity functions technique. We focus on the investigation of attainability sets for 2-D systems. A detailed parametric description of the attainability domains for various types of control inputs for stochastic Brusselator is presented. It is shown that the new regulator provides a low level of stochastic sensitivity and can suppress oscillations of large amplitude.

  9. Thickness-self-controlled synthesis of porous transparent polyaniline-reduced graphene oxide composites towards advanced bifacial dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Sheng; Li, Shin-Ming; Hsiao, Sheng-Tsung; Liao, Wei-Hao; Yang, Shin-Yi; Tien, Hsi-Wen; Ma, Chen-Chi M.; Hu, Chi-Chang

    2014-08-01

    A powerful synthesis strategy is proposed for fabricating porous polyaniline-reduced graphene oxide (PANI-RGO) composites with transparency up to 80% and thickness from 300 to 1000 nm for the counter electrode (CE) of bifacial dye-sensitizing solar cells (DSSCs). The first step is to combine the in-situ positive charge transformation of graphene oxide (GO) through aniline (ANI) prepolymerization and the electrostatic adsorption of ANI oligomer-GO to effectively control the thickness of ultrathin PANI-GO films by adjusting pH of the polymerization media. In the second step, PANI-GO films are reduced with hydroiodic acid to simultaneously enhance the apparent redox activity for the I3-/I- couple and their electronic conductivity. Incorporating the RGO increases the transparency of PANI and facilitates the light-harvesting from the rear side. A DSSC assembled with such a transparent PANI-RGO CE exhibits an excellent efficiency of 7.84%, comparable to 8.19% for a semi-transparent Pt-based DSSC. The high light-harvesting ability of PANI-RGO enhances the efficiency retention between rear- and front-illumination modes to 76.7%, compared with 69.1% for a PANI-based DSSC. The higher retention reduces the power-to-weight ratio and the total cost of bifacial DSSCs, which is also promising in other applications, such as windows, power generators, and panel screens.

  10. Morphology-controlled cactus-like branched anatase TiO2 arrays with high light-harvesting efficiency for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wu, Wu-Qiang; Rao, Hua-Shang; Feng, Hao-Lin; Guo, Xin-Dong; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-08-01

    The present work establishes a facile process for one-step hydrothermal growth of vertically aligned anatase cactus-like branched TiO2 (CBT) arrays on a transparent conducting oxide (TCO) substrate. Various CBT morphologies are obtained by adjusting the potassium titanium oxide oxalate (PTO) reactant concentration (from 0.05 M to 0.15 M) and this yields a morphologically-controllable branched TiO2 arrays geometry. The CBT arrays consist of a vertically oriented nanowire (NW) or nanosheet (NS) stem and a host of short nanorod (NR) branches. The hierarchical CBT arrays demonstrate their excellent candidatures as photoanodes, which are capable of exhibiting high light-harvesting efficiency in dye-sensitized solar cells (DSSCs). Consequently, DSSCs based on 7 μm long optimized CBT arrays (0.05 M PTO), which are assembled with high density and high aspect-ratio NR branches, exhibit an impressive power conversion efficiency of 6.43% under AM 1.5G one sun illumination. The high performance can be attributed to the prominent light-harvesting efficiency, resulting from larger surface area and superior light-scattering capability.

  11. Effects of size-controlled TiO2 nanopowders synthesized by chemical vapor condensation process on conversion efficiency of dye-sensitized solar cells.

    PubMed

    Kim, Woo-Byoung; Lee, Jai-Sung

    2013-07-01

    To investigate the microstructural effects of the synthesized TiO2 nanopowders such as particle size, specific surface area, pore size and pore distributions for the application of an anode material of dye-sensitized solar cells (DSSC), size-controlled and well-dispersed TiO2 nanopowders were synthesized by chemical vapor condensation (CVC) process in the range of 800-1000 degreesC under a pressure of 50 mbar. The average particle size of synthesized TiO2 nanopowders was increased with increasing temperature from 13 nm for 800 degreesC, 15 nm for 900 degreesC and 26 nm. The specific surface area of synthesized nanoparticles were measured as 119.1 m2/g for 800 degreesC, 104.7 m2/g for 900 degreesC and 59.5 m2/g for 1000 degreesC, respectively. The conversion efficiency values (eta%) of DSSC with the synthesized TiO2 nanopowders at 800 degreesC, 900 degreesC, and 1000 degreesC were 2.59%, 5.96% and 3.66%, respectively. The highest conversion efficiency obtained in the 900 degreesC (5.96%) sample is thought to be attributable to homogeneous particle size and pore distributions, large specific surface area, and high transmittance in regions of dye absorption wavelength.

  12. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells.

    PubMed

    Shaikh, Shoyebmohamad F; Mane, Rajaram S; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-shim

    2016-02-09

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, (13)C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  13. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-Shim

    2016-02-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol.

  14. D-sorbitol-induced phase control of TiO2 nanoparticles and its application for dye-sensitized solar cells

    PubMed Central

    Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Min, Byoung Koun; Hwang, Yun Jeong; Joo, Oh-shim

    2016-01-01

    Using a simple hydrothermal synthesis, the crystal structure of TiO2 nanoparticles was controlled from rutile to anatase using a sugar alcohol, D-sorbitol. Adding small amounts of D-sorbitol to an aqueous TiCl4 solution resulted in changes in the crystal phase, particle size, and surface area by affecting the hydrolysis rate of TiCl4. These changes led to improvements of the solar-to-electrical power conversion efficiency (η) of dye-sensitized solar cells (DSSC) fabricated using these nanoparticles. A postulated reaction mechanism concerning the role of D-sorbitol in the formation of rutile and anatase was proposed. Fourier-transform infrared spectroscopy, 13C NMR spectroscopy, and dynamic light scattering analyses were used to better understand the interaction between the Ti precursor and D-sorbitol. The crystal phase and size of the synthesized TiO2 nanocrystallites as well as photovoltaic performance of the DSSC were examined using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and photocurrent density-applied voltage spectroscopy measurement techniques. The DSSC fabricated using the anatase TiO2 nanoparticles synthesized in the presence of D-sorbitol, exhibited an enhanced η (6%, 1.5-fold improvement) compared with the device fabricated using the rutile TiO2 synthesized without D-sorbitol. PMID:26857963

  15. Sensitive-cell-based fish chromatophore biosensor

    NASA Astrophysics Data System (ADS)

    Plant, Thomas K.; Chaplen, Frank W.; Jovanovic, Goran; Kolodziej, Wojtek; Trempy, Janine E.; Willard, Corwin; Liburdy, James A.; Pence, Deborah V.; Paul, Brian K.

    2004-07-01

    A sensitive biosensor (cytosensor) has been developed based on color changes in the toxin-sensitive colored living cells of fish. These chromatophores are highly sensitive to the presence of many known and unknown toxins produced by microbial pathogens and undergo visible color changes in a dose-dependent manner. The chromatophores are immobilized and maintained in a viable state while potential pathogens multiply and fish cell-microbe interactions are monitored. Low power LED lighting is used to illuminate the chromatophores which are magnified using standard optical lenses and imaged onto a CCD array. Reaction to toxins is detected by observing changes is the total area of color in the cells. These fish chromatophores are quite sensitive to cholera toxin, Staphococcus alpha toxin, and Bordatella pertussis toxin. Numerous other toxic chemical and biological agents besides bacterial toxins also cause readily detectable color effects in chromatophores. The ability of the chromatophore cell-based biosensor to distinguish between different bacterial pathogens was examined. Toxin producing strains of Salmonella enteritis, Vibrio parahaemolyticus, and Bacillus cereus induced movement of pigmented organelles in the chromatophore cells and this movement was measured by changes in the optical density over time. Each bacterial pathogen elicited this measurable response in a distinctive and signature fashion. These results suggest a chromatophore cell-based biosensor assay may be applicable for the detection and identification of virulence activities associated with certain air-, food-, and water-borne bacterial pathogens.

  16. Dye-sensitized nanocrystalline solar cells.

    PubMed

    Peter, Laurence M

    2007-06-01

    The basic physical and chemical principles behind the dye-sensitized nanocrystalline solar cell (DSC: also known as the Grätzel cell after its inventor) are outlined in order to clarify the differences and similarities between the DSC and conventional semiconductor solar cells. The roles of the components of the DSC (wide bandgap oxide, sensitizer dye, redox electrolyte or hole conductor, counter electrode) are examined in order to show how they influence the performance of the system. The routes that can lead to loss of DSC performance are analyzed within a quantitative framework that considers electron transport and interfacial electron transfer processes, and strategies to improve cell performance are discussed. Electron transport and trapping in the mesoporous oxide are discussed, and a novel method to probe the electrochemical potential (quasi Fermi level) of electrons in the DSC is described. The article concludes with an assessment of the prospects for future development of the DSC concept.

  17. Morphology control studies of TiO2 microstructures via surfactant-assisted hydrothermal process for dye-sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Lekphet, Woranan; Ke, Tsai-Chyuan; Su, Chaochin; Kathirvel, Sasipriya; Sireesha, Pedaballi; Akula, Suri Babu; Li, Wen-Ren

    2016-09-01

    The controlled morphological TiO2 particles have gained great importance in a wide variety of applications due to their promising physico-chemical properties. In this study, TiO2 microstructures with various shapes to utilize as scattering layer in dye-sensitized solar cell (DSSC) applications were successfully synthesized via different hydrothermal conditions. The effects of the versatile preparation parameters including the amount of titania precursor and surfactant, the addition of ethanol/water, and the hydrothermal process temperature and time on the TiO2 morphology were investigated. The structural and morphological analysis clearly shown that the preparation conditions played crucial roles in the morphology, particle size, and crystalline phase of the TiO2 microparticles. Different kinds of shapes such as rice- (∼1.10 μm (l) and ∼0.41 μm (w)), star- (∼3.60 μm) and flower-like (3.75 μm) TiO2 morphological structures were obtained. The morphology and size of the TiO2 particles were mainly governed by the concentrations of titanium tetraisopropoxide (TTIP) precursor, amounts of tetramethylammonium hydroxide (TMAH) surfactant and hydrothermal temperatures and durations. The as-prepared rice-shaped TiO2 was composed of mixed anatase and brookite binary phases, whereas the star- and flower-shaped TiO2 microstructures were consisted of ternary anatase, rutile, and brookite crystalline TiO2 phases. The three different rice-, star-, and flower-shaped TiO2 microstructures were employed as scattering layers for photoanodes in DSSCs. Among them, the star-like TiO2 photoanode based DSSC exhibited the highest power conversion efficiency of 9.56%, which was also better than those of the devices fabricated without scattering layer (a-TiO2, 8.38%) and with commercial P25 as scattering layer (a-TiO2/P25-TiO2, 8.52%) at the same film thickness of ∼14 μm.

  18. Stretchable, wearable dye-sensitized solar cells.

    PubMed

    Yang, Zhibin; Deng, Jue; Sun, Xuemei; Li, Houpu; Peng, Huisheng

    2014-05-01

    A stretchable, wearable dye-sensitized solar-cell textile is developed from elastic, electrically conducting fiber as a counter electrode and spring-like titanium wire as the working electrode. Dyesensitized solar cells are demonstrated with energy-conversion efficiencies up to 7.13%. The high energy-conversion efficiencies can be well maintained under stretch by 30% and after stretch for 20 cycles.

  19. Improved photovoltaic performance and stability of quantum dot sensitized solar cells using Mn-ZnSe shell structure with enhanced light absorption and recombination control

    NASA Astrophysics Data System (ADS)

    Gopi, Chandu V. V. M.; Venkata-Haritha, M.; Kim, Soo-Kyoung; Kim, Hee-Je

    2015-07-01

    To make quantum-dot-sensitized solar cells (QDSSCs) competitive, photovoltaic parameters comparable to those of other emerging solar cell technologies are necessary. In the present study, ZnSe was used as an alternative to ZnS, one of the most widely used passivation materials in QDSSCs. ZnSe was deposited on a TiO2-CdS-CdSe photoanode to form a core-shell structure, which was more efficient in terms of reducing the electron recombination in QDSSCs. The development of an efficient passivation layer is a requirement for preventing recombination processes in order to attain high-performance and stable QDSSCs. A layer of inorganic Mn-ZnSe was applied to a QD-sensitized photoanode to enhance the adsorption and strongly inhibit interfacial recombination processes in QDSSCs, which greatly improved the power conversion efficiency. Impedance spectroscopy revealed that the combined Mn doping with ZnSe treatment reduces interfacial recombination and increases charge collection efficiency compared with Mn-ZnS, ZnS, and ZnSe. A solar cell based on the CdS-CdSe-Mn-ZnSe photoanode yielded excellent performance with a solar power conversion efficiency of 5.67%, Voc of 0.584 V, and Jsc of 17.59 mA cm-2. Enhanced electron transport and reduced electron recombination are responsible for the improved Jsc and Voc of the QDSSCs. The effective electron lifetime of the device with Mn-ZnSe was higher than those with Mn-ZnS, ZnSe, and ZnS, leading to more efficient electron-hole separation and slower electron recombination.To make quantum-dot-sensitized solar cells (QDSSCs) competitive, photovoltaic parameters comparable to those of other emerging solar cell technologies are necessary. In the present study, ZnSe was used as an alternative to ZnS, one of the most widely used passivation materials in QDSSCs. ZnSe was deposited on a TiO2-CdS-CdSe photoanode to form a core-shell structure, which was more efficient in terms of reducing the electron recombination in QDSSCs. The development of an

  20. Semiconductor quantum dot-sensitized solar cells.

    PubMed

    Tian, Jianjun; Cao, Guozhong

    2013-10-31

    Semiconductor quantum dots (QDs) have been drawing great attention recently as a material for solar energy conversion due to their versatile optical and electrical properties. The QD-sensitized solar cell (QDSC) is one of the burgeoning semiconductor QD solar cells that shows promising developments for the next generation of solar cells. This article focuses on recent developments in QDSCs, including 1) the effect of quantum confinement on QDSCs, 2) the multiple exciton generation (MEG) of QDs, 3) fabrication methods of QDs, and 4) nanocrystalline photoelectrodes for solar cells. We also make suggestions for future research on QDSCs. Although the efficiency of QDSCs is still low, we think there will be major breakthroughs in developing QDSCs in the future.

  1. Semiconductor quantum dot-sensitized solar cells

    PubMed Central

    Tian, Jianjun; Cao, Guozhong

    2013-01-01

    Semiconductor quantum dots (QDs) have been drawing great attention recently as a material for solar energy conversion due to their versatile optical and electrical properties. The QD-sensitized solar cell (QDSC) is one of the burgeoning semiconductor QD solar cells that shows promising developments for the next generation of solar cells. This article focuses on recent developments in QDSCs, including 1) the effect of quantum confinement on QDSCs, 2) the multiple exciton generation (MEG) of QDs, 3) fabrication methods of QDs, and 4) nanocrystalline photoelectrodes for solar cells. We also make suggestions for future research on QDSCs. Although the efficiency of QDSCs is still low, we think there will be major breakthroughs in developing QDSCs in the future. PMID:24191178

  2. Elf5-centered transcription factor hub controls trophoblast stem cell self-renewal and differentiation through stoichiometry-sensitive shifts in target gene networks

    PubMed Central

    Latos, Paulina A.; Sienerth, Arnold R.; Murray, Alexander; Senner, Claire E.; Muto, Masanaga; Ikawa, Masahito; Oxley, David; Burge, Sarah; Cox, Brian J.; Hemberger, Myriam

    2015-01-01

    Elf5 is a transcription factor with pivotal roles in the trophoblast compartment, where it reinforces a trophoblast stem cell (TSC)-specific transcriptional circuit. However, Elf5 is also present in differentiating trophoblast cells that have ceased to express other TSC genes such as Cdx2 and Eomes. In the present study, we aimed to elucidate the context-dependent role of Elf5 at the interface between TSC self-renewal and the onset of differentiation. We demonstrate that precise levels of Elf5 are critical for normal expansion of the TSC compartment and embryonic survival, as Elf5 overexpression triggers precocious trophoblast differentiation. Through integration of protein interactome, transcriptome, and genome-wide chromatin immunoprecipitation data, we reveal that this abundance-dependent function is mediated through a shift in preferred Elf5-binding partners; in TSCs, Elf5 interaction with Eomes recruits Tfap2c to triply occupied sites at TSC-specific genes, driving their expression. In contrast, the Elf5 and Tfap2c interaction becomes predominant as their protein levels increase. This triggers binding to double- and single-occupancy sites that harbor the cognate Tfap2c motif, causing activation of the associated differentiation-promoting genes. These data place Elf5 at the center of a stoichiometry-sensitive transcriptional network, where it acts as a molecular switch governing the balance between TSC proliferation and differentiation. PMID:26584622

  3. Elf5-centered transcription factor hub controls trophoblast stem cell self-renewal and differentiation through stoichiometry-sensitive shifts in target gene networks.

    PubMed

    Latos, Paulina A; Sienerth, Arnold R; Murray, Alexander; Senner, Claire E; Muto, Masanaga; Ikawa, Masahito; Oxley, David; Burge, Sarah; Cox, Brian J; Hemberger, Myriam

    2015-12-01

    Elf5 is a transcription factor with pivotal roles in the trophoblast compartment, where it reinforces a trophoblast stem cell (TSC)-specific transcriptional circuit. However, Elf5 is also present in differentiating trophoblast cells that have ceased to express other TSC genes such as Cdx2 and Eomes. In the present study, we aimed to elucidate the context-dependent role of Elf5 at the interface between TSC self-renewal and the onset of differentiation. We demonstrate that precise levels of Elf5 are critical for normal expansion of the TSC compartment and embryonic survival, as Elf5 overexpression triggers precocious trophoblast differentiation. Through integration of protein interactome, transcriptome, and genome-wide chromatin immunoprecipitation data, we reveal that this abundance-dependent function is mediated through a shift in preferred Elf5-binding partners; in TSCs, Elf5 interaction with Eomes recruits Tfap2c to triply occupied sites at TSC-specific genes, driving their expression. In contrast, the Elf5 and Tfap2c interaction becomes predominant as their protein levels increase. This triggers binding to double- and single-occupancy sites that harbor the cognate Tfap2c motif, causing activation of the associated differentiation-promoting genes. These data place Elf5 at the center of a stoichiometry-sensitive transcriptional network, where it acts as a molecular switch governing the balance between TSC proliferation and differentiation. PMID:26584622

  4. Autophagy sensitivity of neuroendocrine lung tumor cells.

    PubMed

    Hong, Seung-Keun; Kim, Jin-Hwan; Starenki, Dmytro; Park, Jong-In

    2013-12-01

    Neuroendocrine (NE) phenotypes characterize a spectrum of lung tumors, including low-grade typical and intermediate-grade atypical carcinoid, high-grade large-cell NE carcinoma and small cell lung carcinoma. Currently, no effective treatments are available to cure NE lung tumors, demanding identification of biological features specific to these tumors. Here, we report that autophagy has an important role for NE lung tumor cell proliferation and survival. We found that the expression levels of the autophagy marker LC3 are relatively high in a panel of lung tumor cell lines expressing high levels of neuron-specific enolase (NSE), a key NE marker in lung tumors. In response to bafilomycin A1 and chloroquine, NE lung tumor cells exhibited cytotoxicity whereas non-NE lung tumor cells exhibited cytostasis, indicating a distinct role of autophagy for NE lung tumor cell survival. Intriguingly, in certain NE lung tumor cell lines, the levels of processed LC3 (LC3-II) were inversely correlated with AKT activity. When AKT activity was inhibited using AKTi or MK2206, the levels of LC3-II and SQSTM1/p62 were increased. In contrast, torin 1, rapamycin or mTOR knockdown increased p62 levels, suggesting that these two pathways have opposing effects on autophagy in certain NE lung tumors. Moreover, inhibition of one pathway resulted in reduced activity of the other, suggesting that these two pathways crosstalk in the tumors. These results suggest that NE lung tumor cells share a common feature of autophagy and are more sensitive to autophagy inhibition than non-NE lung tumor cells. PMID:24126619

  5. AG490 and PF431396 Sensitive Tyrosine Kinase Control the Population Heterogeneity of Basal STAT1 Activity in Ube1l Deficient Cells.

    PubMed

    Now, Hesung; Yoo, Joo-Yeon

    2016-01-01

    A population often contains distinct sub-populations, thereby increasing the complexity of the overall heterogeneity. However, the cellular origin and biological relevance of sub-populations in cell population have not been clearly identified. Here we demonstrated the novel roles of ISGylation, which is an IFN-induced post-translational modification, controlling heterogeneity at the population level in cultured adherent cells. Without UBE1L, an E1 enzyme of ISGylation, mouse embryonic fibroblasts (MEF) exhibited low viral resistance despite high STAT1 and ISG expression compared with the wild-type MEF. We observe that Ube1l-/- MEF populations consist of two behaviorally distinguishable sub-populations with distinct basal STAT1 activity, while wild-type MEF populations are unimodal. This population heterogeneity in Ube1l knock-out cells was perturbed by tyrosine kinase inhibitors, AG490 and PF431396. In contrast, the neutralization of type I IFN did not affect population heterogeneity. Based on these results, we concluded that UBE1L functions to adjust basal immunological states with the regulation of population heterogeneity. PMID:27427993

  6. AG490 and PF431396 Sensitive Tyrosine Kinase Control the Population Heterogeneity of Basal STAT1 Activity in Ube1l Deficient Cells

    PubMed Central

    Now, Hesung; Yoo, Joo-Yeon

    2016-01-01

    A population often contains distinct sub-populations, thereby increasing the complexity of the overall heterogeneity. However, the cellular origin and biological relevance of sub-populations in cell population have not been clearly identified. Here we demonstrated the novel roles of ISGylation, which is an IFN-induced post-translational modification, controlling heterogeneity at the population level in cultured adherent cells. Without UBE1L, an E1 enzyme of ISGylation, mouse embryonic fibroblasts (MEF) exhibited low viral resistance despite high STAT1 and ISG expression compared with the wild-type MEF. We observe that Ube1l−/− MEF populations consist of two behaviorally distinguishable sub-populations with distinct basal STAT1 activity, while wild-type MEF populations are unimodal. This population heterogeneity in Ube1l knock-out cells was perturbed by tyrosine kinase inhibitors, AG490 and PF431396. In contrast, the neutralization of type I IFN did not affect population heterogeneity. Based on these results, we concluded that UBE1L functions to adjust basal immunological states with the regulation of population heterogeneity. PMID:27427993

  7. Recent advances in sensitized mesoscopic solar cells.

    PubMed

    Grätzel, Michael

    2009-11-17

    -intensive high vacuum and materials purification steps that are currently employed in the fabrication of all other thin-film solar cells. Organic materials are abundantly available, so that the technology can be scaled up to the terawatt scale without running into feedstock supply problems. This gives organic-based solar cells an advantage over the two major competing thin-film photovoltaic devices, i.e., CdTe and CuIn(As)Se, which use highly toxic materials of low natural abundance. However, a drawback of the current embodiment of OPV cells is that their efficiency is significantly lower than that for single and multicrystalline silicon as well as CdTe and CuIn(As)Se cells. Also, polymer-based OPV cells are very sensitive to water and oxygen and, hence, need to be carefully sealed to avoid rapid degradation. The research discussed within the framework of this Account aims at identifying and providing solutions to the efficiency problems that the OPV field is still facing. The discussion focuses on mesoscopic solar cells, in particular, dye-sensitized solar cells (DSCs), which have been developed in our laboratory and remain the focus of our investigations. The efficiency problem is being tackled using molecular science and nanotechnology. The sensitizer constitutes the heart of the DSC, using sunlight to pump electrons from a lower to a higher energy level, generating in this fashion an electric potential difference, which can exploited to produce electric work. Currently, there is a quest for sensitizers that achieve effective harnessing of the red and near-IR part of sunlight, converting these photons to electricity better than the currently used generation of dyes. Progress in this area has been significant over the past few years, resulting in a boost in the conversion efficiency of the DSC that will be reviewed. PMID:19715294

  8. Cell death sensitization of leukemia cells by opioid receptor activation

    PubMed Central

    Friesen, Claudia; Roscher, Mareike; Hormann, Inis; Fichtner, Iduna; Alt, Andreas; Hilger, Ralf A.; Debatin, Klaus-Michael; Miltner, Erich

    2013-01-01

    Cyclic AMP (cAMP) regulates a number of cellular processes and modulates cell death induction. cAMP levels are altered upon stimulation of specific G-protein-coupled receptors inhibiting or activating adenylyl cyclases. Opioid receptor stimulation can activate inhibitory Gi-proteins which in turn block adenylyl cyclase activity reducing cAMP. Opioids such as D,L-methadone induce cell death in leukemia cells. However, the mechanism how opioids trigger apoptosis and activate caspases in leukemia cells is not understood. In this study, we demonstrate that downregulation of cAMP induced by opioid receptor activation using the opioid D,L-methadone kills and sensitizes leukemia cells for doxorubicin treatment. Enhancing cAMP levels by blocking opioid-receptor signaling strongly reduced D,L-methadone-induced apoptosis, caspase activation and doxorubicin-sensitivity. Induction of cell death in leukemia cells by activation of opioid receptors using the opioid D,L-methadone depends on critical levels of opioid receptor expression on the cell surface. Doxorubicin increased opioid receptor expression in leukemia cells. In addition, the opioid D,L-methadone increased doxorubicin uptake and decreased doxorubicin efflux in leukemia cells, suggesting that the opioid D,L-methadone as well as doxorubicin mutually increase their cytotoxic potential. Furthermore, we found that opioid receptor activation using D,L-methadone alone or in addition to doxorubicin inhibits tumor growth significantly in vivo. These results demonstrate that opioid receptor activation via triggering the downregulation of cAMP induces apoptosis, activates caspases and sensitizes leukemia cells for doxorubicin treatment. Hence, opioid receptor activation seems to be a promising strategy to improve anticancer therapies. PMID:23633472

  9. 9-{beta}-arabinofuranosyladenine preferentially sensitizes radioresistant squamous cell carcinoma cell lines to x-rays

    SciTech Connect

    Heaton, D.; Mustafi, R.; Schwartz, J.L. |

    1992-06-01

    The effect of 9-{beta}-arabinofuranosyladenine (ara-A) on sensitivity to the deleterious effects of x-rays was studied in six squamous cell carcinoma cell lines. Three lines were relatively radioresistant, having D{sub 0} values of 2.31 to 2.89 Gy, and the other three lines were relatively radiosensitive, having D{sub 0} values of between 1.07 and 1.45 Gy. Ara-A (50 or 500 {mu}M) was added to cultures 30 min prior to irradiation and removed 30 min after irradiation, and sensitivity was measured in terms of cell survival. The radiosensitizing effect of ara-A was very dependent on the inherent radiosensitivity of the tumor cell line. Fifty micromolar concentrations of ara-A sensitized only the two most radioresistant lines, SCC-12B.2 and JSQ-3. Five hundred micromolar concentrations of ara-A sensitized the more sensitive cell lines, SQ-20B and SQ-9G, but failed to have any effect on the radiation response of the two most sensitive cell lines, SQ-38 and SCC-61. Concentrations of ara-A as low as 10 {mu}M were equally efficient in inhibiting DNA synthesis in all six cell lines. These results suggest that the target for the radiosensitizing effect of ara-A is probably related to the factor controlling the inherent radiosensitivity of human tumor cells. Therefore, ara-A might be useful in overcoming radiation resistance in vivo.

  10. Dye-sensitized Schottky barrier solar cells

    DOEpatents

    Skotheim, Terje A.

    1978-01-01

    A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

  11. Protons sensitize epithelial cells to mesenchymal transition.

    PubMed

    Wang, Minli; Hada, Megumi; Saha, Janapriya; Sridharan, Deepa M; Pluth, Janice M; Cucinotta, Francis A

    2012-01-01

    Proton radiotherapy has gained more favor among oncologists as a treatment option for localized and deep-seated tumors. In addition, protons are a major constituent of the space radiation astronauts receive during space flights. The potential for these exposures to lead to, or enhance cancer risk has not been well studied. Our objective is to study the biological effects of low energy protons on epithelial cells and its propensity to enhance transforming growth factor beta 1 (TGFβ1)-mediated epithelial-mesenchymal transition (EMT), a process occurring during tumor progression and critical for invasion and metastasis. Non-transformed mink lung epithelial cells (Mv1Lu) and hTERT- immortalized human esophageal epithelial cells (EPC) were used in this study. EMT was identified by alterations in cell morphology, EMT-related gene expression changes determined using real-time PCR, and EMT changes in specific cellular markers detected by immunostaining and western blotting. Although TGFβ1 treatment alone is able to induce EMT in both Mv1Lu and EPC cells, low energy protons (5 MeV) at doses as low as 0.1 Gy can enhance TGFβ1 induced EMT. Protons alone can also induce a mild induction of EMT. SD208, a potent TGFβ Receptor 1 (TGFβR1) kinase inhibitor, can efficiently block TGFβ1/Smad signaling and attenuate EMT induction. We suggest a model for EMT after proton irradiation in normal and cancerous tissue based on our results that showed that low and high doses of protons can sensitize normal human epithelial cells to mesenchymal transition, more prominently in the presence of TGFβ1, but also in the absence of TGFβ1.

  12. Protons Sensitize Epithelial Cells to Mesenchymal Transition

    PubMed Central

    Wang, Minli; Hada, Megumi; Saha, Janapriya; Sridharan, Deepa M.; Pluth, Janice M.; Cucinotta, Francis A.

    2012-01-01

    Proton radiotherapy has gained more favor among oncologists as a treatment option for localized and deep-seated tumors. In addition, protons are a major constituent of the space radiation astronauts receive during space flights. The potential for these exposures to lead to, or enhance cancer risk has not been well studied. Our objective is to study the biological effects of low energy protons on epithelial cells and its propensity to enhance transforming growth factor beta 1 (TGFβ1)-mediated epithelial-mesenchymal transition (EMT), a process occurring during tumor progression and critical for invasion and metastasis. Non-transformed mink lung epithelial cells (Mv1Lu) and hTERT- immortalized human esophageal epithelial cells (EPC) were used in this study. EMT was identified by alterations in cell morphology, EMT-related gene expression changes determined using real-time PCR, and EMT changes in specific cellular markers detected by immunostaining and western blotting. Although TGFβ1 treatment alone is able to induce EMT in both Mv1Lu and EPC cells, low energy protons (5 MeV) at doses as low as 0.1 Gy can enhance TGFβ1 induced EMT. Protons alone can also induce a mild induction of EMT. SD208, a potent TGFβ Receptor 1 (TGFβR1) kinase inhibitor, can efficiently block TGFβ1/Smad signaling and attenuate EMT induction. We suggest a model for EMT after proton irradiation in normal and cancerous tissue based on our results that showed that low and high doses of protons can sensitize normal human epithelial cells to mesenchymal transition, more prominently in the presence of TGFβ1, but also in the absence of TGFβ1. PMID:22844446

  13. Optimizing the Performance of a Plastic Dye Sensitized Solar Cell

    SciTech Connect

    Lee, B.; Buchholz, D.; Guo, P.; Hwang, D.; Chang, R.P.H.

    2011-05-19

    This article describes that a fluorine plasma treatment can increase the nanopore filling of a plastic electrolyte in a dye-sensitized solar cell to improve its performance. The one-step fluorine treatment can be used in a controlled way to increase the size of nanopores and nanochannels in the TiO{sub 2} nanoparticle electrode and, at the same time, passivate the TiO{sub 2} nanoparticle surfaces. In combination with the fluorine treatment, a sequential electrolyte filling process has been developed that allows the overall cell conversion efficiency to be increased by as much as 25%. The plastic-based electrolyte cells are found to be much more stable compared with their counterpart, the liquid electrolyte cells. Using this new process, and in combination with a photon confinement scheme, the overall cell efficiency can reach to about 9% using a masked frame measurement technique.

  14. Targeting SLUG sensitizes leukemia cells to ADR-induced apoptosis

    PubMed Central

    Wei, Chang-Rong; Liu, Jun; Yu, Xiao-Jun

    2015-01-01

    Background and Aims: Slug is an E-cadherin repressor and a suppressor of PUMA (p53 upregulated modulator of apoptosis) and it has recently been demonstrated that Slug plays an important role in controlling apoptosis. In this study, we examined whether Slug’s ability to silence expression suppresses the growth of leukemia HL-60 cells and/or sensitizes leukemia HL-60 cells to adriamycin (ADR) through induction of apoptosis. Methods: SLUG siRNA was transfected into the HL-60 and HL-60ADR cell lines (an adriamycin resistant cell line). The stably SLUG siRNA transfected HL-60 and HL-60ADR cells was transiently transfected with PUMA siRNA. The mRNA and protein expression of SLUG and PUMA were determined by Quantitative real-time RT-PCR and Western blot assay. The effects of SLUG siRNA alone or combined with ADR or PUMA siRNA on growth and apoptosis in HL-60 and HL-60ADR cells was detected by MTT, ELISA and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. Results: The results showed that SLUG was less expressed in the HL-60 cells, and high expressed in the HL-60ADR cells. Obvious down-regulation of SLUG mRNA and protein levels and up-regulation of PUMA mRNA and protein levels after SLUG siRNA transfection was showed in the HL-60ADR cells. Treatment with ADR induced SLUG mRNA and protein in the HL-60 cells. Significant positive correlation was observed between basal SLUG mRNA and protein and ADR sensitivity. SLUG gene silencing by SLUG siRNA transfection inhibited growth and induced apoptosis, and increased ADR killing of the HL-60 and HL-60ADR cell lines. After the SLUG siRNA transfected HL-60 and HL-60ADR cells was transiently transfected with PUMA siRNA, did not increase ADR killing of the HL-60 and HL-60ADR cell lines. Conclusion: SLUG level positively correlated with sensitivity to ADR. SLUG siRNA could effectively reduce SLUG expression and induce PUMA expression and restore the drug sensitivity of resistant leukemic cells to

  15. Simulated Climate Sensitivity Uncertainty: Control Climate Bias vs. Perturbed Physics

    NASA Astrophysics Data System (ADS)

    Dommenget, D.

    2013-12-01

    In this talk I address the relationship between climate model biases in the control climate and the simulated climate sensitivity. On the basis of a globally resolved energy balance (GREB) model a number of perturbed physics ensembles are discussed. It is illustrated that the uncertainties in the simulated climate sensitivity can be conceptually split into two parts: a direct effect of the perturbed physics on the climate sensitivity independent of the control mean climate and an indirect effect of the perturbed physics by changing the control mean climate, which in turn changes the climate sensitivity, as the climate sensitivity itself is depending on the control climate. It is shown that the two effects are opposing each other. Biases in the control climate are negatively correlated with the climate sensitivity (colder climates have large sensitivities) and perturbed physics are in average positively correlated with the climate sensitivity (perturbed parameters that lead to warmer control climates lead to larger climate sensitivities). In the GREB model the biases in the control climate are more important effect for the regional climate sensitivity uncertainties, but on the global mean climate sensitivity both, the biases in the control climate and the perturbed physics are equally important.

  16. Degradation of cyanoacrylic acid-based organic sensitizers in dye-sensitized solar cells.

    PubMed

    Chen, Cheng; Yang, Xichuan; Cheng, Ming; Zhang, Fuguo; Sun, Licheng

    2013-07-01

    Organic dyes have become widely used in dye-sensitized solar cells (DSSCs) because of their good performance, flexible structural modifications, and low costs. To increase the photostability of organic dye-based DSSCs, we conducted a full study on the degradation mechanism of cyanoacrylic acid-based organic sensitizers in DSSCs. The results showed that with the synergy between water and UV light, the sensitizer could desorb from the TiO2 surface and the cyanoacrylic acid unit of the sensitizer was transformed into the aldehyde group. It was also observed that the water content had a great effect on the degradation process. Our experiments conducted using (18) O-labeled water demonstrated that the oxygen atom of the aldehyde group identified in the degraded dye came from the solvent water in the DSSCs. Therefore, controlling the water content during DSSC fabrication, good sealing of cells, and filtering the UV light are crucial to produce DSSCs that are more durable and robust.

  17. The stimulus-sensitive H2O2-generating system present in human fat-cell plasma membranes is multireceptor-linked and under antagonistic control by hormones and cytokines.

    PubMed

    Krieger-Brauer, H I; Kather, H

    1995-04-15

    Previous work demonstrated that human fat-cells possess a plasma-membrane-bound H2O2-generating system that is activated by insulin. Here we show that this system is under antagonistic control by various hormones and cytokines that typically act through several distinct receptor families. Similarly to insulin, oxytocin and tumour necrosis factor alpha acted as stimulators of NADPH-dependent H2O2 generation, whereas isoprenaline, a beta-adrenergic agonist, had inhibitory effects. Surprisingly, the acidic and basic isoforms of fibroblast growth factor as well as homodimeric platelet-derived growth factor AA and BB had antagonistic stimulatory and inhibitory effects on NADPH-dependent H2O2 generation. The agents tested acted at discrete ligand-specific receptors and their mechanisms of action were membrane-delimited and occurred in the absence of ATP. These findings implied that established pathways of signal transduction, including receptor kinases or second-messenger-dependent protein kinases A and C, were not involved and placed the stimulus-sensitive H2O2-generating system in a position comparable with adenylate cyclase. It was concluded that the stimulus-sensitive H2O2-generating system of human fat-cells meets all criteria of a universal signal-transducing system for hormones and cytokines that may link ligand binding to cell-surface receptors to changes in the intracellular redox equilibrium.

  18. Prostate cancer marker panel with single cell sensitivity in urine

    PubMed Central

    Nickens, Kristen P.; Ali, Amina; Scoggin, Tatiana; Tan, Shyh‐Han; Ravindranath, Lakshmi; McLeod, David G.; Dobi, Albert; Tacha, David; Sesterhenn, Isabell A.; Srivastava, Shiv

    2015-01-01

    Background Over one million men undergo prostate biopsies annually in the United States, a majority of whom due to elevated serum PSA. More than half of the biopsies turn out to be negative for prostate cancer (CaP). The limitations of both the PSA test and the biopsy procedure have led to the development for more precise CaP detection assays in urine (e.g., PCA3, TMPRSS2‐ERG) or blood (e.g., PHI, 4K). Here, we describe the development and evaluation of the Urine CaP Marker Panel (UCMP) assay for sensitive and reproducible detection of CaP cells in post‐digital rectal examination (post‐DRE) urine. Methods The cellular content of the post‐DRE urine was captured on a translucent filter membrane, which is placed on Cytoclear slides for direct evaluation by microscopy and immuno‐cytochemistry (ICC). Cells captured on the membrane were assayed for PSA and Prostein expression to identify prostate epithelial cells, and for ERG and AMACR to identify prostate tumor cells. Immunostained cells were analyzed for quantitative and qualitative features and correlated with biopsy positive and negative status for malignancy. Results The assay was optimized for single cell capture sensitivity and downstream evaluations by spiking a known number of cells from established CaP cell lines, LNCaP and VCaP, into pre‐cleared control urine. The cells captured from the post‐DRE urine of subjects, obtained prior to biopsy procedure, were co‐stained for ERG, AMACR (CaP specific), and Prostein or PSA (prostate epithelium specific) rendering a whole cell based analysis and characterization. A feasibility cohort of 63 post‐DRE urine specimens was assessed. Comparison of the UCMP results with blinded biopsy results showed an assay sensitivity of 64% (16 of 25) and a specificity of 68.8% (22 of 32) for CaP detection by biopsy. Conclusions This pilot study assessing a minimally invasive CaP detection assay with single cell sensitivity cell‐capture and characterization from the

  19. The sensitivity of human mesenchymal stem cells to ionizing radiation

    SciTech Connect

    Chen, M.-F.; Lin, C.-T.; Chen, W.-C.; Yang, C.-T.; Chen, C.-C.; Liao, S.-K.; Liu, J.M.; Lu, C.-H.; Lee, K.-D. . E-mail: kdlee@adm.cgmh.org.tw

    2006-09-01

    Purpose: Recent studies have shown that mesenchymal stem cells (MSCs) obtained from bone marrow transplantation patients originate from the host. This clinical observation suggests that MSCs in their niches could be resistant to irradiation. However, the biologic responses of bone marrow MSCs to irradiation have rarely been described in the literature. Methods and Materials: In this study, human bone marrow-derived, clonally expanded MSCs were used to investigate their sensitivity to irradiation in vitro, and the cellular mechanisms that may facilitate resistance to irradiation. The human lung cancer cell line A549 and the breast cancer cell line HCC1937 were used as controls for radiosensitivity; the former line has been shown to be radioresistant and the latter radiosensitive. We then examined their in vitro biologic changes and sensitivities to radiation therapy. Results: Our results suggest that MSCs are characterized as resistant to irradiation. Several cellular mechanisms were demonstrated that may facilitate resistance to irradiation: ATM protein phosphorylation, activation of cell-cycle checkpoints, double-strand break repair by homologous recombination and nonhomologous end joining (NHEJ), and the antioxidant capacity for scavenging reactive oxygen species. Conclusions: As demonstrated, MSCs possess a better antioxidant reactive oxygen species-scavenging capacity and active double-strand break repair to facilitate their radioresistance. These findings provide a better understanding of radiation-induced biologic responses in MSCs and may lead to the development of better strategies for stem cell treatment and cancer therapy.

  20. DNA repair and radiation sensitivity in mammalian cells

    SciTech Connect

    Chen, D.J.C.; Stackhouse, M.; Chen, D.S.

    1993-02-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  1. DNA repair and radiation sensitivity in mammalian cells

    SciTech Connect

    Chen, D.J.C.; Stackhouse, M. ); Chen, D.S. . Dept. of Radiation Oncology)

    1993-01-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  2. 41 CFR 109-1.5109 - Control of sensitive items.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Control of sensitive...-INTRODUCTION 1.51-Personal Property Management Standards and Practices § 109-1.5109 Control of sensitive items... by each DOE activity/site, taking into consideration value, costs of administration, need for...

  3. Warm-Sensitive Neurons that Control Body Temperature.

    PubMed

    Tan, Chan Lek; Cooke, Elizabeth K; Leib, David E; Lin, Yen-Chu; Daly, Gwendolyn E; Zimmerman, Christopher A; Knight, Zachary A

    2016-09-22

    Thermoregulation is one of the most vital functions of the brain, but how temperature information is converted into homeostatic responses remains unknown. Here, we use an unbiased approach for activity-dependent RNA sequencing to identify warm-sensitive neurons (WSNs) within the preoptic hypothalamus that orchestrate the homeostatic response to heat. We show that these WSNs are molecularly defined by co-expression of the neuropeptides BDNF and PACAP. Optical recordings in awake, behaving mice reveal that these neurons are selectively activated by environmental warmth. Optogenetic excitation of WSNs triggers rapid hypothermia, mediated by reciprocal changes in heat production and loss, as well as dramatic cold-seeking behavior. Projection-specific manipulations demonstrate that these distinct effectors are controlled by anatomically segregated pathways. These findings reveal a molecularly defined cell type that coordinates the diverse behavioral and autonomic responses to heat. Identification of these warm-sensitive cells provides genetic access to the core neural circuit regulating the body temperature of mammals. PAPERCLIP. PMID:27616062

  4. Aqueous dye-sensitized solar cells.

    PubMed

    Bella, Federico; Gerbaldi, Claudio; Barolo, Claudia; Grätzel, Michael

    2015-06-01

    Nowadays, dye-sensitized solar cells (DSSCs) are the most extensively investigated systems for the conversion of solar energy into electricity, particularly for implementation in devices where low cost and good performance are required. Nevertheless, a key aspect is still to be addressed, being considered strongly harmful for a long time, which is the presence of water in the cell, either in the electrolyte or at the electrode/electrolyte interface. Here comes the present review, in the course of which we try our best to address the highly topical role of water in DSSCs, trying to figure out if it is a poisoner or the keyword to success, by means of a thoroughly detailed analysis of all the established phenomena in an aqueous environment. Actually, in the last few years the scientific community has suddenly turned its efforts in the direction of using water as a solvent, as demonstrated by the amount of research articles being published in the literature. Indeed, by means of DSSCs fabricated with water-based electrolytes, reduced costs, non-flammability, reduced volatility and improved environmental compatibility could be easily achieved. As a result, an increasing number of novel electrodes, dyes and electrolyte components are continuously proposed, being highly challenging from the materials science viewpoint and with the golden thread of producing truly water-based DSSCs. If the initial purpose of DSSCs was the construction of an artificial photosynthetic system able to convert solar light into electricity, the use of water as the key component may represent a great step forward towards their widespread diffusion in the market. PMID:25864577

  5. Decentralized control of uncertain systems via sensitivity models

    SciTech Connect

    Schoenwald, D.A.; Oezguener, U.

    1993-06-01

    In this paper, we present a decentralized strategy for optimal control of interconnected systems exhibiting parametric uncertainty. First, we demonstrate that sensitivity models for linear interconnected systems can be generated at each subsystem using only locally available information. Second, we present an optimal control law that incorporates sensitivity functions in the feedback path. The control scheme is completely decentralized and is proposed as a means of making the closed loop system less sensitive to parameter deviations. Finally, we give an example of an interconnected system and show how this control strategy is implemented.

  6. Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ananth, S.; Vivek, P.; Saravana Kumar, G.; Murugakoothan, P.

    2015-02-01

    A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%.

  7. Performance of Caesalpinia sappan heartwood extract as photo sensitizer for dye sensitized solar cells.

    PubMed

    Ananth, S; Vivek, P; Saravana Kumar, G; Murugakoothan, P

    2015-02-25

    A natural dye extracted from Caesalpinia sappan heartwood was used as photo sensitizer for the first time to fabricate titanium dioxide (TiO2) nanoparticles based dye sensitized solar cells. Brazilin and brazilein are the major pigments present in the natural dye and their optimized molecular structure were calculated using Density functional theory (DFT) at 6-31G (d) level. The HOMO-LUMO were performed to reveal the energy gap using optimized structure. Pure TiO2 nanoparticles in anatase phase were synthesized by sol-gel technique. The pure and natural dye sensitized TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Low cost and environment friendly dye sensitized solar cells were fabricated using natural dye sensitized TiO2 based photo anode. The solar light to electron conversion efficiency of Caesalpinia sappan heartwood extract sensitized dye sensitized solar cell is 1.1%.

  8. Punishment sensitivity predicts the impact of punishment on cognitive control.

    PubMed

    Braem, Senne; Duthoo, Wout; Notebaert, Wim

    2013-01-01

    Cognitive control theories predict enhanced conflict adaptation after punishment. However, no such effect was found in previous work. In the present study, we demonstrate in a flanker task how behavioural adjustments following punishment signals are highly dependent on punishment sensitivity (as measured by the Behavioural Inhibition System (BIS) scale): Whereas low punishment-sensitive participants do show increased conflict adaptation after punishment, high punishment-sensitive participants show no such modulation. Interestingly, participants with a high punishment-sensitivity showed an overall reaction time increase after punishments. Our results stress the role of individual differences in explaining motivational modulations of cognitive control.

  9. Space Station Freedom Beta Gimbal Control via Sensitivity Models

    NASA Technical Reports Server (NTRS)

    Schoenwald, David A.; Ozguner, Umit; Graham, Ronald E.

    1993-01-01

    Tracking control of the Space Station Freedom solar array beta gimbals is investigated. Of particular interest is the issue of control in the presence of uncertainty in gimbal friction parameters. Sensitivity functions are incorporated into the feedback loop to desensitize the gimbal control law to parameter variations. Simulation results indicated that one such sensitivity function improves the closed-loop performance of the gimbals in the presence of unexpected friction parameter dispersions.

  10. UMTRA project disposal cell cover biointrusion sensitivity assessment, Revision 1

    SciTech Connect

    1995-10-01

    This study provides an analysis of potential changes that may take place in a Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cell cover system as a result of plant biointrusion. Potential changes are evaluated by performing a sensitivity analysis of the relative impact of root penetrations on radon flux out of the cell cover and/or water infiltration into the cell cover. Data used in this analysis consist of existing information on vegetation growth on selected cell cover systems and information available from published studies and/or other available project research. Consistent with the scope of this paper, no new site-specific data were collected from UMTRA Project sites. Further, this paper does not focus on the issue of plant transport of radon gas or other contaminants out of the disposal cell cover though it is acknowledged that such transport has the potential to be a significant pathway for contaminants to reach the environment during portions of the design life of a disposal cell where plant growth occurs. Rather, this study was performed to evaluate the effects of physical penetration and soil drying caused by plant roots that have and are expected to continue to grow in UMTRA Project disposal cell covers. An understanding of the biological and related physical processes that take place within the cover systems of the UMTRA Project disposal cells helps the U.S. Department of Energy (DOE) determine if the presence of a plant community on these cells is detrimental, beneficial, or of mixed value in terms of the cover system`s designed function. Results of this investigation provide information relevant to the formulation of a vegetation control policy.

  11. Gold nanoparticle sensitize radiotherapy of prostate cancer cells by regulation of the cell cycle

    NASA Astrophysics Data System (ADS)

    Roa, Wilson; Zhang, Xiaojing; Guo, Linghong; Shaw, Andrew; Hu, Xiuying; Xiong, Yeping; Gulavita, Sunil; Patel, Samir; Sun, Xuejun; Chen, Jie; Moore, Ronald; Xing, James Z.

    2009-09-01

    Glucose-capped gold nanoparticles (Glu-GNPs) have been used to improve cellular targeting and radio-sensitization. In this study, we explored the mechanism of Glu-GNP enhanced radiation sensitivity in radiation-resistant human prostate cancer cells. Cell survival and proliferation were measured using MTT and clonogenic assay. Flow cytometry with staining by propidium iodide (PI) was performed to study the cell cycle changes induced by Glu-GNPs, and western blotting was used to determine the expression of p53 and cyclin proteins that correlated to cell cycle regulation. With 2 Gy of ortho-voltage irradiation, Glu-GNP showed a 1.5-2.0 fold enhancement in growth inhibition when compared to x-rays alone. Comparing the cell cycle change, Glu-GNPs induced acceleration in the G0/G1 phase and accumulation of cells in the G2/M phase at 29.8% versus 18.4% for controls at 24 h. G2/M arrest was accompanied by decreased expression of p53 and cyclin A, and increased expression of cyclin B1 and cyclin E. In conclusion, Glu-GNPs trigger activation of the CDK kinases leading to cell cycle acceleration in the G0/G1 phase and accumulation in the G2/M phase. This activation is accompanied by a striking sensitization to ionizing radiation, which may have clinical implications.

  12. Orbit control at the ALS based on sensitivity matrices

    SciTech Connect

    Nishimura, H.; Schachinger, L.; Ohgaki, H.

    1995-04-01

    A third-generation synchrotron-light source storage ring requires accurate orbit correction because its lattice is very sensitive to magnet imperfections and misalignments. If model-based control is used, calibration of this model is required in advance. Therefore, it is preferable to prepare some kind of model-free orbit control scheme that is complementary to model-based control. A sensitivity matrix (S matrix) works effectively as the kernel of a model-free orbit control system for a given optics of a lattice. This paper describes recent efforts in this respect at Advanced Light Source (ALS).

  13. HTLV-1 Tax protein sensitizes cells to apoptotic cell death induced by DNA damaging agents.

    PubMed

    Kao, S Y; Lemoine, F J; Mariott, S J

    2000-04-27

    Transient HTLV-1 Tax expression suppresses cellular nucleotide excision repair, and this effect correlates with Tax transactivation of the proliferating cell nuclear antigen promoter. The inability to repair DNA damage typically induces apoptotic cell death. Therefore, we investigated the effect of Tax-mediated suppression of DNA repair on apoptosis in stable Tax-expressing cells. Constitutive Tax expression reduced cellular nucleotide excision repair activity compared with parental and control cells. Tax-expressing cells were also more sensitive to apoptosis induced by DNA damaging agents than control cells. Even though Tax-expressing cells displayed reduced DNA repair, they showed increased DNA replication following UV damage. These results suggest that Tax suppresses the cell's ability to repair DNA damage and stimulates DNA replication even in the presence of damage. The inability to repair DNA damage is likely to stimulate apoptotic cell death in the majority of Tax-expressing cells while the ability to promote DNA replication may also allow the survival of a small population of cells. We propose that together these effects contribute to the monoclonal nature and low efficiency of HTLV-1 transformation.

  14. Nickel cadmium cell age sensitivity study

    SciTech Connect

    Thierfelder, H.E.; Rampel, G.; Schmerbach, J.

    1984-08-01

    The objective of this study was to investigate the effects of aging on aerospace nickel cadmium cells, and to make a recommendation on the age limitation for cells in flight batteries at time of spacecraft launch. The swelling of the positive plates, and the decrease in overcharge protection, are concluded to be the life limiting characteristics. Based on the criteria of minimum overcharge protection for maximum reliability, it was concluded that the cell age since time of activation, should be no more than three and one-half years at time of launch, to have confidence in completing a 7-1/2 year mission. This study was made using fourteen aerospace nickel cadmium cells, GE/BBD Part No. 42B015AB19. The fourteen cells were made up of two cells from each of seven lots of cells that were manufactured by GE/BBD between 1975 and 1982. The cells had been in cold storage in the shorted condition since approximately three months after activation. The fourteen cells were reconditioned, subjected to the acceptance test identically as at time of manufacture, and then opened for flooded electrode tests and chemical analyses. The electrical acceptance test data showed no correlation with the age of the cells.

  15. A strategy to design novel structure photochromic sensitizers for dye-sensitized solar cells

    PubMed Central

    Wu, Wenjun; Wang, Jiaxing; Zheng, Zhiwei; Hu, Yue; Jin, Jiayu; Zhang, Qiong; Hua, Jianli

    2015-01-01

    Two sensitizers with novel structure were designed and synthetized by introducing photochromic bisthienylethene (BTE) group into the conjugated system. Thanks to the photochromic effect the sensitizers have under ultraviolet and visible light, the conjugated bridge can be restructured and the resulting two photoisomers showed different behaviors in photovoltaic devices. This opens up a new research way for the dye-sensitized solar cells (DSSCs). PMID:25716204

  16. Improved Sensitivity Relations in State Constrained Optimal Control

    SciTech Connect

    Bettiol, Piernicola; Frankowska, Hélène; Vinter, Richard B.

    2015-04-15

    Sensitivity relations in optimal control provide an interpretation of the costate trajectory and the Hamiltonian, evaluated along an optimal trajectory, in terms of gradients of the value function. While sensitivity relations are a straightforward consequence of standard transversality conditions for state constraint free optimal control problems formulated in terms of control-dependent differential equations with smooth data, their verification for problems with either pathwise state constraints, nonsmooth data, or for problems where the dynamic constraint takes the form of a differential inclusion, requires careful analysis. In this paper we establish validity of both ‘full’ and ‘partial’ sensitivity relations for an adjoint state of the maximum principle, for optimal control problems with pathwise state constraints, where the underlying control system is described by a differential inclusion. The partial sensitivity relation interprets the costate in terms of partial Clarke subgradients of the value function with respect to the state variable, while the full sensitivity relation interprets the couple, comprising the costate and Hamiltonian, as the Clarke subgradient of the value function with respect to both time and state variables. These relations are distinct because, for nonsmooth data, the partial Clarke subdifferential does not coincide with the projection of the (full) Clarke subdifferential on the relevant coordinate space. We show for the first time (even for problems without state constraints) that a costate trajectory can be chosen to satisfy the partial and full sensitivity relations simultaneously. The partial sensitivity relation in this paper is new for state constraint problems, while the full sensitivity relation improves on earlier results in the literature (for optimal control problems formulated in terms of Lipschitz continuous multifunctions), because a less restrictive inward pointing hypothesis is invoked in the proof, and because

  17. Characterising dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Tobin, Laura L.; O'Reilly, Thomas; Zerulla, Dominic; Sheridan, John T.

    2009-08-01

    With growing energy and environmental concerns due to fossil fuel depletion and global warming there is an increasing attention being attracted by alternative and/or renewable sources of power such as biomass, hydropower, geothermal, wind and solar energy. In today's society there is a vast and in many cases not fully appreciated dependence on electrical power for everyday life and therefore devices such as PV cells are of enormous importance. The more widely used and commercially available silicon (semiconductor) based cells currently have the greatest efficiencies, however the manufacturing of these cells is complex and costly due to the cost and difficulty of producing and processing pure silicon. One new direction being explored is the development of dye-sensitised solar cells (DSSC). The SFI Strategic Research Centre for Solar Energy Conversion is a new research cluster based in Ireland, formed with the express intention of bringing together industry and academia to produce renewable energy solutions. Our specific area of research is in biomimetic dye sensitised solar cells and their electrical properties. We are currently working to develop test equipment, and optoelectronic models describing the performance and behaviors of dye-sensitised solar cells (Grätzel Cells). In this paper we describe some of the background to our work and also some of our initial experimental results. Based on these results we intend to characterise the opto-electrical properties and bulk characteristics of simple dye-sensitised solar cells and then to proceed to test new cell compositions.

  18. NK sensitivity of neuroblastoma cells determined by a highly sensitive coupled luminescent method

    SciTech Connect

    Ogbomo, Henry; Hahn, Anke; Geiler, Janina; Michaelis, Martin; Doerr, Hans Wilhelm; Cinatl, Jindrich . E-mail: Cinatl@em.uni-frankfurt.de

    2006-01-06

    The measurement of natural killer (NK) cells toxicity against tumor or virus-infected cells especially in cases with small blood samples requires highly sensitive methods. Here, a coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase release from injured target cells was used to evaluate the cytotoxicity of interleukin-2 activated NK cells against neuroblastoma cell lines. In contrast to most other methods, CLM does not require the pretreatment of target cells with labeling substances which could be toxic or radioactive. The effective killing of tumor cells was achieved by low effector/target ratios ranging from 0.5:1 to 4:1. CLM provides highly sensitive, safe, and fast procedure for measurement of NK cell activity with small blood samples such as those obtained from pediatric patients.

  19. Decreased myo-inositol to chiro-inositol (M/C) ratios and increased M/C epimerase activity in PCOS theca cells demonstrate increased insulin sensitivity compared to controls.

    PubMed

    Heimark, Douglas; McAllister, Jan; Larner, Joseph

    2014-01-01

    Previous studies from our and other labs have shown that insulin resistance is associated with an inositol imbalance of excess myo-inositol and deficient chiro-inositol together with a deficiency of myo-inositol to chiro-inositol epimerase in vivo and in vitro. In this report, we utilized well characterized theca cells from normal cycling women, with normal insulin sensitivity, and theca cells from women with polycystic ovary syndrome (PCOS), with increased insulin sensitivity to examine the myo-inositol to chiro-inisitol (M/C) ratio and the myo-inositol to chiro-inositol epimerase activity. PCOS theca cells with increased insulin sensitivity were specifically used to investigate whether the inositol imbalance and myo-inositol to chiro-inositol epimerase are regulated in a similar or the opposite direction than that observed in insulin resistant cells. The results of these studies are the first to demonstrate that in insulin sensitive PCOS theca cells the inositol imbalance goes in the opposite direction to that observed in insulin resistant cells, and there is a decreased M/C ratio and an increased myo-inositol to chiro-inositol epimerase activity. Further biochemical and genetic studies will probe the mechanisms involved.

  20. Sensitivity Analysis and Optimal Control of Anthroponotic Cutaneous Leishmania

    PubMed Central

    Zamir, Muhammad; Zaman, Gul; Alshomrani, Ali Saleh

    2016-01-01

    This paper is focused on the transmission dynamics and optimal control of Anthroponotic Cutaneous Leishmania. The threshold condition R0 for initial transmission of infection is obtained by next generation method. Biological sense of the threshold condition is investigated and discussed in detail. The sensitivity analysis of the reproduction number is presented and the most sensitive parameters are high lighted. On the basis of sensitivity analysis, some control strategies are introduced in the model. These strategies positively reduce the effect of the parameters with high sensitivity indices, on the initial transmission. Finally, an optimal control strategy is presented by taking into account the cost associated with control strategies. It is also shown that an optimal control exists for the proposed control problem. The goal of optimal control problem is to minimize, the cost associated with control strategies and the chances of infectious humans, exposed humans and vector population to become infected. Numerical simulations are carried out with the help of Runge-Kutta fourth order procedure. PMID:27505634

  1. Myt3 suppression sensitizes islet cells to high glucose-induced cell death via Bim induction.

    PubMed

    Tennant, B R; Vanderkruk, B; Dhillon, J; Dai, D; Verchere, C B; Hoffman, B G

    2016-01-01

    Diabetes is a chronic disease that results from the body's inability to properly control circulating blood glucose levels. The loss of glucose homoeostasis can arise from a loss of β-cell mass because of immune-cell-mediated attack, as in type 1 diabetes, and/or from dysfunction of individual β-cells (in conjunction with target organ insulin resistance), as in type 2 diabetes. A better understanding of the transcriptional pathways regulating islet-cell survival is of great importance for the development of therapeutic strategies that target β-cells for diabetes. To this end, we previously identified the transcription factor Myt3 as a pro-survival factor in islets following acute suppression of Myt3 in vitro. To determine the effects of Myt3 suppression on islet-cell survival in vivo, we used an adenovirus to express an shRNA targeting Myt3 in syngeneic optimal and marginal mass islet transplants, and demonstrate that suppression of Myt3 impairs the function of marginal mass grafts. Analysis of grafts 5 weeks post-transplant revealed that grafts transduced with the shMyt3 adenovirus contained ~20% the number of transduced cells as grafts transduced with a control adenovirus. In fact, increased apoptosis and significant cell loss in the shMyt3-transduced grafts was evident after only 5 days, suggesting that Myt3 suppression sensitizes islet cells to stresses present in the early post-transplant period. Specifically, we find that Myt3 suppression sensitizes islet cells to high glucose-induced cell death via upregulation of the pro-apoptotic Bcl2 family member Bim. Taken together these data suggest that Myt3 may be an important link between glucotoxic and immune signalling pathways. PMID:27195679

  2. Characterization of UV radiation sensitive frog cell lines

    SciTech Connect

    Smith-Stein, A.C.

    1983-01-01

    Twenty-one subclones of nine frog cell isolates were tested for sensitivity to a panel of DNA damaging agents. Two clones were identified which had a greater than wild type level of sensitivity to UV radiation but had a wild type level of sensitivity to the other agents. These clones were the haploid RRP602-7 and the diploid RRP802-1. RRP802-1 was found to be unstable with respect to UV sensitivity. The line was cloned in order to isolate stable sensitive and wild type derivatives. RRP802-1-16, a UV sensitive clone and RRP802-1-13, a clone with a wild type level of sensitivity to UV radiation, were isolated. The UV radiation sensitivity of RRP602-7, RRP802-1 and RRP802-1-16 did not correlate with cell size, cell shape, cell cycle distribution or ploidy. The cell cycle distribution after UV irradiation, the rate of DNA synthesis after UV-irradiation, the DNA polymerase ..cap alpha.. activity and the sister chromatid exchange frequency were all measured in RRP602-7, RRP802-1 and RRP802-1-16 in order to examine the DNA repair capacity. The presence of DNA repair pathways was examined directly in RRP602-7, RRP802-1 and RRP802-1-16. All were found to be proficient in photo-reactivation repair and postreplication repair of UV elicited DNA damage.

  3. Cell size control in yeast

    PubMed Central

    Turner, Jonathan J.; Ewald, Jennifer C.; Skotheim, Jan M.

    2012-01-01

    Cell size is an important adaptive trait that influences nearly all aspects of cellular physiology. Despite extensive characterization of the cell cycle regulatory network, the molecular mechanismscoupling growth to division, and thereby controlling cell size, have remained elusive. Recent workin yeast has reinvigorated the size control field and suggested provocative mechanisms forthe distinct functions of setting and sensing cell size. Further examination of size sensing models based on spatial gradients and molecular titration, coupled with elucidation of the pathways responsible for nutrient-modulated target size, may reveal the fundamental principles of eukaryotic cell size control. PMID:22575477

  4. Sensitivity of Dendritic Cells to Microenvironment Signals

    PubMed Central

    Motta, Juliana Maria; Rumjanek, Vivian Mary

    2016-01-01

    Dendritic cells are antigen-presenting cells capable of either activating the immune response or inducing and maintaining immune tolerance. They do this by integrating stimuli from the environment and changing their functional status as a result of plasticity. The modifications suffered by these cells have consequences in the way the organism may respond. In the present work two opposing situations known to affect dendritic cells are analyzed: tumor growth, leading to a microenvironment that favors the induction of a tolerogenic profile, and organ transplantation, which leads to a proinflammatory profile. Lessons learned from these situations may help to understand the mechanisms of modulation resulting not only from the above circumstances, but also from other pathologies. PMID:27088097

  5. PCTAIRE1-knockdown sensitizes cancer cells to TNF family cytokines.

    PubMed

    Yanagi, Teruki; Shi, Ranxin; Aza-Blanc, Pedro; Reed, John C; Matsuzawa, Shu-ichi

    2015-01-01

    While PCTAIRE1/PCTK1/Cdk16 is overexpressed in malignant cells and is crucial in tumorigenesis, its function in apoptosis remains unclear. Here we investigated the role of PCTAIRE1 in apoptosis, especially in the extrinsic cell death pathway. Gene-knockdown of PCTAIRE1 sensitized prostate cancer PPC1 and Du145 cells, and breast cancer MDA-MB-468 cells to TNF-family cytokines, including TNF-related apoptosis-inducing ligand (TRAIL). Meanwhile, PCTAIRE1-knockdown did not sensitize non-malignant cells, including diploid fibroblasts IMR-90 and the immortalized prostate epithelial cell line 267B1. PCTAIRE1-knockdown did not up-regulate death receptor expression on the cell surface or affect caspase-8, FADD and FLIP expression levels. PCTAIRE1-knockdown did promote caspase-8 cleavage and RIPK1 degradation, while RIPK1 mRNA knockdown sensitized PPC1 cells to TNF-family cytokines. Furthermore, the kinase inhibitor SNS-032, which inhibits PCTAIRE1 kinase activity, sensitized PPC1 cells to TRAIL-induced apoptosis. Together these results suggest that PCTAIRE1 contributes to the resistance of cancer cell lines to apoptosis induced by TNF-family cytokines, which implies that PCTAIRE1 inhibitors could have synergistic effects with TNF-family cytokines for cytodestruction of cancer cells. PMID:25790448

  6. A sensitivity analysis for subverting randomization in controlled trials.

    PubMed

    Marcus, S M

    2001-02-28

    In some randomized controlled trials, subjects with a better prognosis may be diverted into the treatment group. This subverting of randomization results in an unobserved non-compliance with the originally intended treatment assignment. Consequently, the estimate of treatment effect from these trials may be biased. This paper clarifies the determinants of the magnitude of the bias and gives a sensitivity analysis that associates the amount that randomization is subverted and the resulting bias in treatment effect estimation. The methods are illustrated with a randomized controlled trial that evaluates the efficacy of a culturally sensitive AIDS education video.

  7. Cell-Size Control

    PubMed Central

    Amodeo, Amanda A.; Skotheim, Jan M.

    2015-01-01

    Cells of a given type maintain a characteristic cell size to function efficiently in their ecological or organismal context. They achieve this through the regulation of growth rates or by actively sensing size and coupling this signal to cell division. We focus this review on potential size-sensing mechanisms, including geometric, external cue, and titration mechanisms. Mechanisms that titrate proteins against DNA are of particular interest because they are consistent with the robust correlation of DNA content and cell size. We review the literature, which suggests that titration mechanisms may underlie cell-size sensing in Xenopus embryos, budding yeast, and Escherichia coli, whereas alternative mechanisms may function in fission yeast. PMID:26254313

  8. Fiber Fabry-Perot interferometer with controllable temperature sensitivity.

    PubMed

    Zhang, Xinpu; Peng, Wei; Zhang, Yang

    2015-12-01

    We proposed a fiber taper based on the Fabry-Perot (FP) interferometer structure with controllable temperature sensitivity. The FP interferometer is formed by inserting a segment of tapered fiber tip into the capillary and subsequently splicing the other end of the capillary to a single-mode fiber (SMF), the tapered fiber endface, and the spliced face form the FP cavity. Through controlling the inserted tapered fiber length, a series of FP interferometers were made. Because the inserted taper tip has the degree of freedom along the fiber axial, when the FP interferometer is subjected to temperature variation, the thermal expansion of the fiber taper tip will resist the FP cavity length change caused by the evolution of capillary length, and we can control the temperature sensitivity by adjusting the inserted taper length. In this structure, the equivalent thermal expansion coefficient of the FP interferometer can be defined; it was used to evaluate the temperature sensitivity of the FP interferometer, which provides an effective method to eliminate the temperature effect and to enhance other measurement accuracy. We fabricated the FP interferometers and calibrated their temperature characters by measuring the wavelength shift of the resonance dips in the reflection spectrum. In a temperature range of 50°C to 150°C, the corresponding temperature sensitivities can be controlled between 0 and 1.97 pm/°C when the inserted taper is between 75 and 160 μm. Because of its controllable temperature sensitivity, ease of fabrication, and low cost, this FP interferometer can meet different temperature sensitivity requirements in various application areas, especially in the fields which need temperature insensitivity. PMID:26625075

  9. Fiber Fabry-Perot interferometer with controllable temperature sensitivity.

    PubMed

    Zhang, Xinpu; Peng, Wei; Zhang, Yang

    2015-12-01

    We proposed a fiber taper based on the Fabry-Perot (FP) interferometer structure with controllable temperature sensitivity. The FP interferometer is formed by inserting a segment of tapered fiber tip into the capillary and subsequently splicing the other end of the capillary to a single-mode fiber (SMF), the tapered fiber endface, and the spliced face form the FP cavity. Through controlling the inserted tapered fiber length, a series of FP interferometers were made. Because the inserted taper tip has the degree of freedom along the fiber axial, when the FP interferometer is subjected to temperature variation, the thermal expansion of the fiber taper tip will resist the FP cavity length change caused by the evolution of capillary length, and we can control the temperature sensitivity by adjusting the inserted taper length. In this structure, the equivalent thermal expansion coefficient of the FP interferometer can be defined; it was used to evaluate the temperature sensitivity of the FP interferometer, which provides an effective method to eliminate the temperature effect and to enhance other measurement accuracy. We fabricated the FP interferometers and calibrated their temperature characters by measuring the wavelength shift of the resonance dips in the reflection spectrum. In a temperature range of 50°C to 150°C, the corresponding temperature sensitivities can be controlled between 0 and 1.97 pm/°C when the inserted taper is between 75 and 160 μm. Because of its controllable temperature sensitivity, ease of fabrication, and low cost, this FP interferometer can meet different temperature sensitivity requirements in various application areas, especially in the fields which need temperature insensitivity.

  10. Large pi-aromatic molecules as potential sensitizers for highly efficient dye-sensitized solar cells.

    PubMed

    Imahori, Hiroshi; Umeyama, Tomokazu; Ito, Seigo

    2009-11-17

    Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Thus far, ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO(2) sensitizers in dye-sensitized solar cells. However, a gradual increment in the highest power conversion efficiency has been recognized in the past decade. More importantly, considering that ruthenium is a rare metal, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. Large pi-aromatic molecules, such as porphyrins, phthalocyanines, and perylenes, are important classes of potential sensitizers for highly efficient dye-sensitized solar cells, owing to their photostability and high light-harvesting capabilities that can allow applications in thinner, low-cost dye-sensitized solar cells. Porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm. Nevertheless, the poor light-harvesting properties relative to the ruthenium complexes have limited the cell performance of porphyrin-sensitized TiO(2) cells. Elongation of the pi conjugation and loss of symmetry in porphyrins cause broadening and a red shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved intensively by the enhanced light absorption. Actually, some push-pull-type porphyrins have disclosed a remarkably high power conversion efficiency (6-7%) that was close to that of the ruthenium complexes. Phthalocyanines exhibit strong absorption around 300 and 700 nm and redox features that are similar to porphyrins. Moreover, phthalocyanines are transparent over a large region of the visible spectrum, thereby enabling the possibility of using them as "photovoltaic windows". However, the cell performance was poor, owing to strong aggregation and lack of directionality in the

  11. Hydroalcoholic extract of Crocus sativus effects on bronchial inflammatory cells in ovalbumin sensitized rats

    PubMed Central

    Mahmoudabady, Maryam; Neamati, Ali; Vosooghi, Somayyeh; Aghababa, Heydar

    2013-01-01

    Objective: Inflammation is one of the major components of asthma. Our aim was to evaluate the effects of C. sativus extract on total and differential white blood cells (WBC) count in lung lavage fluid (LLF) of ovalbumin-sensitized rats. Materials and Methods: Forty rats were divided into five groups (n = 8 for each group) as control (C), sensitized with injection and inhalation of ovalbumin (OA) alone (S), and three groups of sensitized and treated with different doses of C. sativus extract (S50EX, S100EX, and S200EX groups). Total and differential WBC counts of LLF were evaluated in control, sensitized, and treated sensitized groups. Results: Total WBC count, neutrophil, and eosinophil percentage in LLF were increased in sensitized animals compared with the control group (p0.001). Treatment of sensitized animals with all doses of the extract significantly reduced WBC number and the percentage of neutrophil and eosinophil compared with the sensitized animals (p0.01–0.001). Conclusion: According to these results, the extract of C. sativus could be effective on alleviating lung inflammatory cells specially eosinophils in lung lavage of sensitized animals which may indicate a preventive effect of this plant on lung inflammation in asthma. PMID:25050293

  12. 48 CFR 952.204-71 - Sensitive foreign nations controls.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Sensitive foreign nations controls. 952.204-71 Section 952.204-71 Federal Acquisition Regulations System DEPARTMENT OF ENERGY CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses...

  13. 41 CFR 109-1.5109 - Control of sensitive items.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false Control of sensitive items. 109-1.5109 Section 109-1.5109 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS GENERAL...

  14. 41 CFR 109-1.5109 - Control of sensitive items.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false Control of sensitive items. 109-1.5109 Section 109-1.5109 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS GENERAL...

  15. 41 CFR 109-1.5109 - Control of sensitive items.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Control of sensitive items. 109-1.5109 Section 109-1.5109 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS GENERAL...

  16. Sensitivity method for integrated structure/active control law design

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.

    1987-01-01

    The development is described of an integrated structure/active control law design methodology for aeroelastic aircraft applications. A short motivating introduction to aeroservoelasticity is given along with the need for integrated structures/controls design algorithms. Three alternative approaches to development of an integrated design method are briefly discussed with regards to complexity, coordination and tradeoff strategies, and the nature of the resulting solutions. This leads to the formulation of the proposed approach which is based on the concepts of sensitivity of optimum solutions and multi-level decompositions. The concept of sensitivity of optimum is explained in more detail and compared with traditional sensitivity concepts of classical control theory. The analytical sensitivity expressions for the solution of the linear, quadratic cost, Gaussian (LQG) control problem are summarized in terms of the linear regulator solution and the Kalman Filter solution. Numerical results for a state space aeroelastic model of the DAST ARW-II vehicle are given, showing the changes in aircraft responses to variations of a structural parameter, in this case first wing bending natural frequency.

  17. Labeling of mesenchymal stem cells for MRI with single-cell sensitivity

    PubMed Central

    Ariza de Schellenberger, Angela; Kratz, Harald; Farr, Tracy D; Löwa, Norbert; Hauptmann, Ralf; Wagner, Susanne; Taupitz, Matthias; Schnorr, Jörg; Schellenberger, Eyk A

    2016-01-01

    Sensitive cell detection by magnetic resonance imaging (MRI) is an important tool for the development of cell therapies. However, clinically approved contrast agents that allow single-cell detection are currently not available. Therefore, we compared very small iron oxide nanoparticles (VSOP) and new multicore carboxymethyl dextran-coated iron oxide nanoparticles (multicore particles, MCP) designed by our department for magnetic particle imaging (MPI) with discontinued Resovist® regarding their suitability for detection of single mesenchymal stem cells (MSC) by MRI. We achieved an average intracellular nanoparticle (NP) load of >10 pg Fe per cell without the use of transfection agents. NP loading did not lead to significantly different results in proliferation, colony formation, and multilineage in vitro differentiation assays in comparison to controls. MRI allowed single-cell detection using VSOP, MCP, and Resovist® in conjunction with high-resolution T2*-weighted imaging at 7 T with postprocessing of phase images in agarose cell phantoms and in vivo after delivery of 2,000 NP-labeled MSC into mouse brains via the left carotid artery. With optimized labeling conditions, a detection rate of ~45% was achieved; however, the experiments were limited by nonhomogeneous NP loading of the MSC population. Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI. Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection. In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist® for improved MRI of MSC with single-cell sensitivity. PMID:27110112

  18. Labeling of mesenchymal stem cells for MRI with single-cell sensitivity.

    PubMed

    Ariza de Schellenberger, Angela; Kratz, Harald; Farr, Tracy D; Löwa, Norbert; Hauptmann, Ralf; Wagner, Susanne; Taupitz, Matthias; Schnorr, Jörg; Schellenberger, Eyk A

    2016-01-01

    Sensitive cell detection by magnetic resonance imaging (MRI) is an important tool for the development of cell therapies. However, clinically approved contrast agents that allow single-cell detection are currently not available. Therefore, we compared very small iron oxide nanoparticles (VSOP) and new multicore carboxymethyl dextran-coated iron oxide nanoparticles (multicore particles, MCP) designed by our department for magnetic particle imaging (MPI) with discontinued Resovist(®) regarding their suitability for detection of single mesenchymal stem cells (MSC) by MRI. We achieved an average intracellular nanoparticle (NP) load of >10 pg Fe per cell without the use of transfection agents. NP loading did not lead to significantly different results in proliferation, colony formation, and multilineage in vitro differentiation assays in comparison to controls. MRI allowed single-cell detection using VSOP, MCP, and Resovist(®) in conjunction with high-resolution T2*-weighted imaging at 7 T with postprocessing of phase images in agarose cell phantoms and in vivo after delivery of 2,000 NP-labeled MSC into mouse brains via the left carotid artery. With optimized labeling conditions, a detection rate of ~45% was achieved; however, the experiments were limited by nonhomogeneous NP loading of the MSC population. Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI. Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection. In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist(®) for improved MRI of MSC with single-cell sensitivity. PMID:27110112

  19. Monobenzoporphyrins as Sensitizers for Dye-Sensitized Solar Cells: Observation of Significant Spacer-Group Effect.

    PubMed

    Jinadasa, R G Waruna; Li, Bihong; Schmitz, Benjamin; Kumar, Siddhartha; Hu, Yi; Kerr, Lei; Wang, Hong

    2016-08-23

    A series of monobenzoporphyrins (WH1-WH4) bearing different conjugated spacer groups were designed and synthesized as sensitizers for dye-sensitized solar cells. Although a phenyl spacer only has a minimal impact on the absorption bands of the monobenzoporphyrin, an ethynylphenyl (WH3) or a vinyl (WH4) spacer redshifts and broadens the absorption bands of the dyes to result in much enhanced light-harvesting ability. Dye-sensitized solar cells based on these monobenzoporphyrin dyes displayed remarkable differences in power conversion efficiencies (PCEs). The monobenzoporphyrin bearing no spacer (WH1) resulted in a PCE of only 0.5 %; in contrast, the monobenzoporphyrin bearing vinyl spacers (WH4) achieved a PCE of 5.2 %. The high efficiency of the WH4 cell is attributed to the higher light-harvesting ability, the lesser extent of aggregation on the TiO2 surface, and the more favorable electron-density distributions of the HOMO and LUMO for electron injection and collection. This work demonstrates the exceptional tunability of benzoporphyrins as sensitizers for dye-sensitized solar cells. PMID:27469616

  20. Monobenzoporphyrins as Sensitizers for Dye-Sensitized Solar Cells: Observation of Significant Spacer-Group Effect.

    PubMed

    Jinadasa, R G Waruna; Li, Bihong; Schmitz, Benjamin; Kumar, Siddhartha; Hu, Yi; Kerr, Lei; Wang, Hong

    2016-08-23

    A series of monobenzoporphyrins (WH1-WH4) bearing different conjugated spacer groups were designed and synthesized as sensitizers for dye-sensitized solar cells. Although a phenyl spacer only has a minimal impact on the absorption bands of the monobenzoporphyrin, an ethynylphenyl (WH3) or a vinyl (WH4) spacer redshifts and broadens the absorption bands of the dyes to result in much enhanced light-harvesting ability. Dye-sensitized solar cells based on these monobenzoporphyrin dyes displayed remarkable differences in power conversion efficiencies (PCEs). The monobenzoporphyrin bearing no spacer (WH1) resulted in a PCE of only 0.5 %; in contrast, the monobenzoporphyrin bearing vinyl spacers (WH4) achieved a PCE of 5.2 %. The high efficiency of the WH4 cell is attributed to the higher light-harvesting ability, the lesser extent of aggregation on the TiO2 surface, and the more favorable electron-density distributions of the HOMO and LUMO for electron injection and collection. This work demonstrates the exceptional tunability of benzoporphyrins as sensitizers for dye-sensitized solar cells.

  1. Spatiotemporally controlled single cell sonoporation

    PubMed Central

    Fan, Zhenzhen; Liu, Haiyan; Mayer, Michael; Deng, Cheri X.

    2012-01-01

    This paper presents unique approaches to enable control and quantification of ultrasound-mediated cell membrane disruption, or sonoporation, at the single-cell level. Ultrasound excitation of microbubbles that were targeted to the plasma membrane of HEK-293 cells generated spatially and temporally controlled membrane disruption with high repeatability. Using whole-cell patch clamp recording combined with fluorescence microscopy, we obtained time-resolved measurements of single-cell sonoporation and quantified the size and resealing rate of pores. We measured the intracellular diffusion coefficient of cytoplasmic RNA/DNA from sonoporation-induced transport of an intercalating fluorescent dye into and within single cells. We achieved spatiotemporally controlled delivery with subcellular precision and calcium signaling in targeted cells by selective excitation of microbubbles. Finally, we utilized sonoporation to deliver calcein, a membrane-impermeant substrate of multidrug resistance protein-1 (MRP1), into HEK-MRP1 cells, which overexpress MRP1, and monitored the calcein efflux by MRP1. This approach made it possible to measure the efflux rate in individual cells and to compare it directly to the efflux rate in parental control cells that do not express MRP1. PMID:23012425

  2. New materials for hybrid dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Diacon, Aurel; Fara, Laurentiu; Cincu, Corneliu; Mitroi, Mihai Razvan; Zaharia, Catalin; Rusen, Edina; Boscornea, Cristian; Rosu, Constantin; Comaneci, Dragos

    2010-10-01

    This paper deals with the synthesis and characterization of new phtalocyanine based chromophores and new electrolyte for the fabrication of dye-sensitized solar cells (DSSCs) and hybrid dye-sensitized solar cells. The new phtalocyanines-based chromophores contain a different number of pending carboxy groups. The classic electrolyte was replaced by polymers that contain quaternary ammonium salts or polymer modified with PbS and CdS nanoparticles. This type of photovoltaic cells is not presented so far in the literature. Cell set-up involves TiO 2 deposition followed by dye adsorption and polymer film formation in the case of hybrid cells. The electrical parameters of the studied solar cells, namely the short-circuit current density Jsc and the open circuit voltage Voc, were measured.

  3. Probenecid Sensitizes Neuroblastoma Cancer Stem Cells to Cisplatin.

    PubMed

    Campos-Arroyo, Denise; Maldonado, Vilma; Bahena, Ivan; Quintanar, Valeria; Patiño, Nelly; Carlos Martinez-Lazcano, Juan; Melendez-Zajgla, Jorge

    2016-01-01

    We used both in vitro cultures of neuroblastoma cell lines and nude-mice xenotransplants to explore the effects of co-administration of cisplatin and probenecid. Probenecid sensitized neuroblastoma cells, including tumor cells with stem features, to the effects of cisplatin, both in vitro and in vivo. This effect was mediated by an increase in the apoptotic cell death and a concomitant decrease in cell proliferation. This effect is accompanied by modulation of the mRNA and protein of the drug efflux transporters MDR1, MRP2, and BCRP. The co-administration of probenecid with cisplatin should be explored as a possible therapeutic strategy. PMID:26963048

  4. Dye-Sensitized Solar Cells for Space Power

    NASA Technical Reports Server (NTRS)

    Harris, Jerry D.; Hehemann, David G.; Duraj, Stan A.

    2003-01-01

    During the course of this grant, dye-sensitized solar cells were prepared and characterized. The solar cells were prepared using materials (dyes, electrolytes, transparent conductive oxide coated glass, nanocrystalline TiO2) entirely prepared in-house, as well as prepared using materials available commercially. Complete cells were characterized under simulated AM0 illumination. The best cell prepared at NASA had an AM0 efficiency of 1.22% for a 1.1 sq cm cell. Short circuit current (Isc), open circuit voltage (Voc) and fill factor (FF) for the cell were 6.95 mA, 618 mV and 42.8%, respectively. For comparison purposes, two commercially prepared dye-sensitized solar cells were obtained from Solaronix SA, Aubonne, Switzerland. The Solaronix cells were also characterized under simulated AM0 illumination. The best cell from Solaronix had an active area of 3.71 sq cm and measured an AM0 efficiency of 3.16%. with Isc, Voc and FF of 45.80 mA, 669.6 mV and 52.3%, respectively. Both cells from Solaronix were rapid thermal cycled between -80 C and 80 C. Thermal cycling led to a 4.6% loss of efficiency in one of the cells and led to nearly a complete failure in the second cell.

  5. Near-infrared squaraine co-sensitizer for high-efficiency dye-sensitized solar cells.

    PubMed

    Rao, G Hanumantha; Venkateswararao, A; Giribabu, L; Han, Liyuan; Bedja, Idriss; Gupta, Ravindra Kumar; Islam, Ashraful; Singh, Surya Prakash

    2016-06-01

    A combination of squaraine-based dyes (SPSQ1 and SPSQ2) and a ruthenium-based dye (N3) were chosen as co-sensitizers to construct efficient dye-sensitized solar cells. The co-sensitization of squaraine dyes with N3 enhanced their light-harvesting properties as a result of the broad spectral coverage in the region 350-800 nm. The co-sensitized solar cells based on SPSQ2 + N3 showed the highest short circuit current density of 17.10 mA cm(-2), an open circuit voltage of 0.66 V and a fill factor of 0.73, resulting in the highest power conversion efficiency of 8.2%, which is higher than that of the dye-sensitized solar cells based on the individual SPSQ1 and SPSQ2 dyes. The high power conversion efficiency of SPSQ2 + N3 was ascribed to its good light-harvesting properties, which resulted from its broader incident photon current conversion spectrum than that of the individual dyes. The high electron life time and electron recombination, which were the main causes of the higher efficiency of the device, were successfully analysed and correlated using transient absorption spectrometry and intensity-modulated photovoltage spectrometry.

  6. Pressure sensitivity of the vapor-cell atomic clock.

    PubMed

    Iyanu, Gebriel; Wang, He; Camparo, James

    2009-06-01

    Although atomic clocks have very low levels of frequency instability, they are nonetheless sensitive (albeit slightly) to various environmental parameters, including temperature, power supply voltage, and dc magnetic fields. In the terrestrial environment, however, atmospheric pressure (i.e., the air's molecular density) is not generally included in this list, because the air's density variations near the surface of the earth will typically have a negligible effect on the clock's performance. The situation is different, however, for clocks onboard satellites like Galileo, where manufacturing and testing are done at atmospheric pressure, while operation is in vacuum. The pressure sensitivity of atomic clocks, in particular vapor-cell atomic clocks, can therefore be of significance. Here, we discuss some of the ways in which changes in atmospheric pressure affect vapor-cell atomic clocks, and we demonstrate that, for one device, the pressure-sensitivity traces back to a pressure-induced change in the temperature of the clock's filter and resonance cells.

  7. Enhanced sensitivity of tumorigenic cells to rapid rounding induced by phenylalaninol.

    PubMed

    Mak, W W; Pinteric, L; Wong, J T

    1980-09-01

    This study describes a rounding reaction induced in mammalian cells by the addition of phenylalaninol. In the Chinese hamster ovary tsH1 line the rounding occurred rapidly with a half time of 1 min at 25 mM phenylalaninol. After the removal of phenylalaninol, the rounding was reversed, leading to the reflattening of the cells with a half-time of 3.5 min. Rounding was inhibited by dibutyryl-cAMP and testosterone, and reflattening by cytochalasin B. Either in the case of the tsH1 line and its growth-control revertant GRC+L-73, or in the case of SV40-transformed and untransformed human WI-38 cells, the transformed cells displayed a weakened resistance toward rounding. Likewise rat cells transformed by th highly oncogenic adenovirus-12 were more sensitive to rounding than cells transformed by the poorly oncogenic adenovirus-5, which in turn were more sensitive than untransformed cells. However, drug-resistant cell-surface mutants of the Chinese hamster ovary GAT- line also exhibited an altered sensitivity to rounding. These findings suggest that more than one cellular component determines cellular sensitivity to phenylalaninol-induced rounding. One of these components is specifically altered, giving rise to an enhanced sensitivity, in the course of tumorigenic transformation. PMID:6257353

  8. Multidisciplinary optimization of controlled space structures with global sensitivity equations

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.

    1991-01-01

    A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.

  9. Controlled reflectance solar cell

    SciTech Connect

    Dill, H.G.; Lillington, D.R.

    1989-06-13

    A solar cell is described comprising: A semiconductor body having a front layer of a first conductivity type and an adjacent back layer of a second conductivity type opposite of the first conductivity type. The front and back layers form front and back major surfaces, respectively the semiconductor body further having openings through the back major surface and back layer which form recesses extending to the front layer. The recesses having walls which are doped to the first conductivity type; a first electrical contact disposed in the recesses making electrical contact the first conductivity type layer; and a second electrical contact disposed on the back major surface making electrical contact to the second conductivity type layer.

  10. Calcium influences sensitivity to growth inhibition induced by a cell surface sialoglycopeptide

    NASA Technical Reports Server (NTRS)

    Betz, N. A.; Fattaey, H. K.; Johnson, T. C.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    While studies concerning mitogenic factors have been an important area of research for many years, much less is understood about the mechanisms of action of cell surface growth inhibitors. We have purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS-18) which can reversibly inhibit the proliferation of diverse cell types. The studies discussed in this article show that three mouse keratinocyte cell lines exhibit sixty-fold greater sensitivity than other fibroblasts and epithelial-like cells to CeReS-18-induced growth inhibition. Growth inhibition induced by CeReS-18 treatment is a reversible process, and the three mouse keratinocyte cell lines exhibited either single or multiple cell cycle arrest points, although a predominantly G0/G1 cell cycle arrest point was exhibited in Swiss 3T3 fibroblasts. The sensitivity of the mouse keratinocyte cell lines to CeReS-18-induced growth inhibition was not affected by the degree of tumorigenic progression in the cell lines and was not due to differences in CeReS-18 binding affinity or number of cell surface receptors per cell. However, the sensitivity of both murine fibroblasts and keratinocytes could be altered by changing the extracellular calcium concentration, such that increased extracellular calcium concentrations resulted in decreased sensitivity to CeReS-18-induced proliferation inhibition. Thus the increased sensitivity of the murine keratinocyte cell lines to CeReS-18 could be ascribed to the low calcium concentration used in their propagation. Studies are currently under way investigating the role of calcium in CeReS-18-induced growth arrest. The CeReS-18 may serve as a very useful tool to study negative growth control and the signal transduction events associated with cell cycling.

  11. Adoptive cell transfer of contact sensitivity-initiation mediated by nonimmune cells sensitized with monoclonal IgE antibodies. Dependence on host skin mast cells.

    PubMed

    Matsuda, H; Ushio, H; Paliwal, V; Ptak, W; Askenase, P W

    1995-05-15

    A role for mast cell release of serotonin (5-HT), via Ag-specific factors derived from Thy-1+ B220+ lymphoid cells in the initiation of murine contact sensitivity (CS) has been suggested. However, because CS in mast cell-deficient mice was intact, a role for mast cells in CS initiation was unclear. Therefore, we examined whether CS could be initiated by i.v. injection of nonimmune mixed lymphoid cells that were sensitized in vitro with IgE. When naive mice received IgE-sensitized nonimmune spleen or lymph node cells, or IgE-sensitized purified mast cells, together with immune CS-effector B220- T cells, which therefore were depleted of CS-initiating, Thy-1+, B220+ cells, which could not transfer CS, then reconstitution of CS occurred. Mast cell-deficient W/Wv mice could not elicit this IgE-dependent CS ear swelling, but when mast cell deficiency was reversed by ear injection of normal bone marrow-derived cultured mast cells, then CS was restored. In vitro pretreatment with irrelevant monoclonal anti-OVA IgE prevented CS initiation mediated by Ag-specific, IgE mAb-sensitized cells, presumably by blocking sensitization with IgE. Thus Fc epsilon R on the normal lymphoid cells were involved. When ketanserin, a 5-HT2 receptor antagonist, was injected i.v. before cell transfer, CS initiation via IgE-sensitized cells and CS were no longer elicited. Thus, in this system, IgE Abs bound to circulating IgE Fc epsilon R bearing lymphoid cells sensitized in vitro (most likely basophils), probably mediated early activation of these circulating basophils to release mediators, causing 5-HT release from cutaneous mast cells, to mediate CS initiation. PMID:7730614

  12. Space Environmental Testing of Dye-Sensitized Solar Cells

    NASA Technical Reports Server (NTRS)

    Harris, Jerry D.; Anglin, Emily J.; Hepp, Aloysius F.; Bailey, Sheila G.; Scheiman, David A.; Castro, Stephenie L.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Recent advances in nanocrystalline dye-sensitized solar cells has lead NASA to investigate the potential of these devices for space power generation, Reported here is the first space environment characterization of these type of photovoltaic devices. Cells containing liquid electrolytes were exposed to simulated low-earth orbit conditions and their performance evaluated. All cells were characterized under simulated air mass zero (AMO) illumination. Complete cells were exposed to pressures less than 1 x 10(exp -7) torr for over a month, with no sign of sealant failure or electrolyte leakage. Cells from Solaronix SA were rapid thermal cycled under simulated low-earth orbit conditions. The cells were cycled 100 times from -80 C to 80 C, which is equivalent to 6 days in orbit. The best cell had a 4.6% loss in efficiency as a result of the thermal cycling,

  13. Photodamage of the cells in culture sensitized with bilirubin

    NASA Astrophysics Data System (ADS)

    Kozlenkova, O. A.; Plavskaya, L. G.; Mikulich, A. V.; Leusenko, I. A.; Tretyakova, A. I.; Plavskii, V. Yu

    2016-08-01

    It has been shown that exposure to radiation of LED sources of light with an emission band maximum at about 465 and 520 nm having substantially identical damaging effects on animal cells in culture, that are in a logarithmic growth phase and preincubated with pigment. Photobiological effect is caused by photodynamic processes involving singlet oxygen generated by triplet excited sensitizer. Mono-exponential type dependence of cell survival on the energy dose indicates that it is bilirubin that acts as a sensitizer but not its photoproducts. The inclusion of bilirubin in the cells, where it is primarily localized in the mitochondria cells, it is accompanied by multiple amplification photochemical stability compared to pigment molecules bound with albumin

  14. Etoposide sensitizes neuroblastoma cells expressing caspase 8 to TRAIL.

    PubMed

    Kim, Hye Ryung; Lee, Myoung Woo; Kim, Dae Seong; Jo, Ha Yeong; Lee, Soo Hyun; Chueh, Hee Won; Jung, Hye Lim; Yoo, Keon Hee; Sung, Ki Woong; Koo, Hong Hoe

    2012-01-01

    TRAIL [TNF (tumour necrosis factor)-related apoptosis-inducing ligand] is a promising agent for clinical use since it kills a wide range of tumour cells without affecting normal cells. We provide evidence that pretreatment with etoposide significantly enhanced TRAIL-mediated apoptosis via up-regulation of DR5 (death receptor 5 or TRAIL-R2) expression in the caspase 8 expressing neuroblastoma cell line, SK-N-MC. In addition, sequential treatment with etoposide and TRAIL increased caspases 8, 9 and 3 activation, Mcl-1 cleavage and Bid truncation, which suggests that the ability of etoposide and TRAIL to induce apoptosis is mediated through activation of an intrinsic signalling pathway. Although TRAIL-R2 expression increased in IMR-32 cells in response to etoposide treatment, cell death was not increased by concurrent treatment with TRAIL compared with etoposide alone, because the cells lacked caspase 8 expression. Restoration of caspase 8 expression by exposure to IFNγ (interferon γ) sensitizes IMR-32 cells to TRAIL. Moreover, pretreatment with etoposide increased TRAIL-induced apoptosis in caspase 8 restored IMR-32 cells through activation of a caspase cascade that included caspases 8, 9 and 3. These results indicate that the etoposide-mediated sensitization of neuroblastoma cells to TRAIL is associated with an increase in TRAIL-R2 expression and requires caspase 8 expression. These observations support the potential use of a combination of etoposide and TRAIL in future clinical trials. PMID:23124518

  15. Quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapeutic agents.

    PubMed

    Wang, Wenge; Gallant, Jean-Nicolas; Katz, Sharyn I; Dolloff, Nathan G; Smith, Charles D; Abdulghani, Junaid; Allen, Joshua E; Dicker, David T; Hong, Bo; Navaraj, Arunasalam; El-Deiry, Wafik S

    2011-08-01

    Quinacrine has been widely explored in treatment of malaria, giardiasis, and rheumatic diseases. We find that quinacrine stabilizes p53 and induces p53-dependent and independent cell death. Treatment by quinacrine alone at concentrations of 10-20 mM for 1-2 d cannot kill hepatocellular carcinoma cells, such as HepG2, Hep3B, Huh7, which are also resistant to TRAIL. However, quinacrine renders these cells sensitive to treatment by TRAIL. Co-treatment of these cells with quinacrine and TRAIL induces overwhelming cell death within 3-4 h. Levels of DR5, a pro-apoptotic death receptor of TRAIL, are increased upon treatment with quinacrine, while levels of Mcl-1, an anti-apoptotic member of the Bcl-2 family, are decreased. While the synergistic effect of quinacrine with TRAIL appears to be in part independent of p53, knockdown of p53 in HepG2 cells by siRNA results in more cell death after treatment by quinacrine and TRAIL. The mechanism by which quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapies, and the potential for clinical application currently are being further explored. Lastly, quinacrine synergizes with chemotherapeutics, such as adriamycin, 5-FU, etoposide, CPT11, sorafenib, and gemcitabine, in killing hepatocellular carcinoma cells in vitro and the drug enhances the activity of sorafenib to delay tumor growth in vivo. PMID:21725212

  16. Control of in vivo (cellular) phleomycin sensitivity by nuclear genotype, growth phase, and metal ions

    SciTech Connect

    Moore, C.W.

    1982-03-01

    Nuclear genotype, growth phase, and the presence of metal ions all proved to be important in controlling the lethal effects of phleomycin in eukaryotic Saccharomyces cerevisiae. Among 120 normal and radiation-sensitive strains compared for their sensitivities to lethal effects of phleomycin, all mutant strains exhibiting enhanced sensitivities to phleomycin killing were also sensitive to killing by ionizing radiation. Mutants exhibiting sensitivities to phleomycin similar to normal strains of the same ploidy were sensitive to ultraviolet radiation. We conclude that cellular recovery from phleomycin-induced damage in yeast depends upon the function of some or all of 13 independent genes and upon at least some of the same steps in cellular pathways for the biological repair of damage by ionizing radiation. In this respect, the action of phleomycin is similar to the action of its structurally similar analog, bleomycin, even though phleomycin was substantially more cytotoxic. Stationary-phase haploid yeast cells were more sensitive than exponentially growing cells to killing by phleomycin. Survival of stationary-phase yeast was reduced to 0.3 +/- 0.07% (S.E.) after 20-min exposures to phleomycin (1 microgram/ml; approximately 6.7 x 10(-7) M), but lethal effects of phleomycin were completely eradicated (98% survival) by the presence of 0.05 M ethylenediaminetetraacetate during the treatment period. The inactivation indicates an important role for one or more metal ion(s) in the in vivo toxicity of the phleomycin-bleomycin group of anticancer antibiotics.

  17. Organic sensitizers for dye-sensitized solar cell (DSSC): Properties from computation, progress and future perspectives

    NASA Astrophysics Data System (ADS)

    Obotowo, I. N.; Obot, I. B.; Ekpe, U. J.

    2016-10-01

    The advent of the dye-sensitized solar cells (DSSCs) came at a time when the quest for alternative energy was high, replacing p-n junction photovoltaic devices. Its uniqueness arises from the fact that unlike the conventional systems where the semiconductor assumes the task of light absorption and charge transport, the two functions are separated in DSSC. Organic sensitizers have been used to harvest a large fraction of sunlight ranging from the UV region to the near infrared region of the spectrum leading to power conversion efficiencies of up to ∼ 10.65 % for metal-free organic sensitizers. Currently, experimental analysis of photo sensitizers utilized in DSSCs is often a trial and error process, often laborious and require extensive and expensive chemical synthesis. In most cases, disappointing results from late-stage of the dye synthesis indicate an urgent need to understand the properties of the dyes at a molecular level, before experiments take place. Fortunately, the use of quantum chemical calculations especially Density Functional Theory (DFT) to screen potential dyes has helped in developing efficient sensitizers and to reduce cost. In the present review article, we discuss the current state of the field, new concepts, design strategies, challenges facing the theoretical design and development of organic sensitizers for DSSCs and future perspectives.

  18. Mesenchymal stem cells are sensitive to bleomycin treatment

    PubMed Central

    Nicolay, Nils H.; Rühle, Alexander; Perez, Ramon Lopez; Trinh, Thuy; Sisombath, Sonevisay; Weber, Klaus-Josef; Ho, Anthony D.; Debus, Jürgen; Saffrich, Rainer; Huber, Peter E.

    2016-01-01

    Mesenchymal stem cells (MSCs) have been shown to attenuate pulmonary damage induced by bleomycin-based anticancer treatments, but the influence of bleomycin on the stem cells themselves remains largely unknown. Here, we demonstrate that human bone marrow-derived MSCs are relatively sensitive to bleomycin exposure compared to adult fibroblasts. MSCs revealed increased levels of apoptosis after bleomycin treatment, while cellular morphology, stem cell surface marker expression and the ability for adhesion and migration remained unchanged. Bleomycin treatment also resulted in a reduced adipogenic differentiation potential of these stem cells. MSCs were found to efficiently repair DNA double strand breaks induced by bleomycin, mostly through non-homologous end joining repair. Low mRNA and protein expression levels of the inactivating enzyme bleomycin hydrolase were detected in MSCs that may contribute to the observed bleomycin-sensitive phenotype of these cells. The sensitivity of MSCs against bleomycin needs to be taken into consideration for ongoing and future treatment protocols investigating these stem cells as a potential treatment option for bleomycin-induced pulmonary damage in the clinic. PMID:27215195

  19. Interfacial Engineering for Quantum-Dot-Sensitized Solar Cells.

    PubMed

    Shen, Chao; Fichou, Denis; Wang, Qing

    2016-04-20

    Quantum-dot-sensitized solar cells (QDSCs) are promising solar-energy-conversion devices, as low-cost alternatives to the prevailing photovoltaic technologies. Compared with molecular dyes, nanocrystalline quantum dot (QD) light absorbers exhibit higher molar extinction coefficients and a tunable photoresponse. However, the power-conversion efficiencies (PCEs) of QDSCs are generally below 9.5 %, far behind their molecular sensitizer counterparts (up to 13 %). These low PCEs have been attributed to a large free-energy loss during sensitizer regeneration, energy loss during the charge-carrier transport and transfer processes, and inefficient charge separation at the QD/electrolyte interfaces, and various interfacial engineering strategies for enhancing the PCE and cell stability have been reported. Herein, we review recent progress in the interfacial engineering of QDSCs and discuss future prospects for the development of highly efficient and stable QDSCs. PMID:26879244

  20. Interplay between transparency and efficiency in dye sensitized solar cells.

    PubMed

    Tagliaferro, Roberto; Colonna, Daniele; Brown, Thomas M; Reale, Andrea; Di Carlo, Aldo

    2013-02-11

    In this paper we analyze the interplay between transparency and efficiency in dye sensitized solar cells by varying fabrication parameters such as the thickness of the nano-crystalline TiO(2) layer, the dye loading and the dye type. Both transparency and efficiency show a saturation trend when plotted versus dye loading. By introducing the transparency-efficiency plot, we show that the relation between transparency and efficiency is linear and is almost independent on the TiO(2) thickness for a certain thickness range. On the contrary, the relation between transparency and efficiency depends strongly on the type of the dye. Moreover, we show that co-sensitization techniques can be effectively used to access regions of the transparency-efficiency space that are forbidden for single dye sensitization. The relation found between transparency and efficiency (T&E) can be the general guide for optimization of Dye Solar Cells in building integration applications.

  1. Aerogel tempelated ZnO dye-sensitized solar cells.

    SciTech Connect

    Hamann, T. W.; Martinson , A. B. E.; Elam, J. W.; Pellin, M. J.; Hupp, J. T.; Materials Science Division; Northwestern Univ.

    2008-01-01

    Atomic layer deposition is employed to conformally coat low density, high surface area aerogel films with ZnO. The ZnO/aerogel membranes are incorporated as photoanodes in dye-sensitized solar cells, which exhibit excellent power efficiencies of up to 2.4% under 100 mW cm{sup -2} light intensity.

  2. Fuel utilization and fuel sensitivity of solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Huang, Kevin

    2011-03-01

    Fuel utilization and fuel sensitivity are two important process variables widely used in operation of SOFC cells, stacks, and generators. To illustrate the technical values, the definitions of these two variables as well as practical examples are particularly given in this paper. It is explicitly shown that the oxygen-leakage has a substantial effect on the actual fuel utilization, fuel sensitivity and V-I characteristics. An underestimation of the leakage flux could potentially results in overly consuming fuel and oxidizing Ni-based anode. A fuel sensitivity model is also proposed to help extract the leakage flux information from a fuel sensitivity curve. Finally, the "bending-over" phenomenon observed in the low-current range of a V-I curve measured at constant fuel-utilization is quantitatively coupled with leakage flux.

  3. Improved method increases sensitivity for circulating hepatocellular carcinoma cells

    PubMed Central

    Liu, Hui-Ying; Qian, Hai-Hua; Zhang, Xiao-Feng; Li, Jun; Yang, Xia; Sun, Bin; Ma, Jun-Yong; Chen, Lei; Yin, Zheng-Feng

    2015-01-01

    AIM: To improve an asialoglycoprotein receptor (ASGPR)-based enrichment method for detection of circulating tumor cells (CTCs) of hepatocellular carcinoma (HCC). METHODS: Peripheral blood samples were collected from healthy subjects, patients with HCC or various other cancers, and patients with hepatic lesions or hepatitis. CTCs were enriched from whole blood by extracting CD45-expressing leukocytes with monoclonal antibody coated-beads following density gradient centrifugation. The remaining cells were cytocentrifuged on polylysine-coated slides. Isolated cells were treated by triple immunofluorescence staining with CD45 antibody and a combination of antibodies against ASGPR and carbamoyl phosphate synthetase 1 (CPS1), used as liver-specific markers, and costained with DAPI. The cell slide was imaged and stained tumor cells that met preset criteria were counted. Recovery, sensitivity and specificity of the detection methods were determined and compared by spiking experiments with various types of cultured human tumor cell lines. Expression of ASGPR and CPS1 in cultured tumor cells and tumor tissue specimens was analyzed by flow cytometry and triple immunofluorescence staining, respectively. RESULTS: CD45 depletion of leukocytes resulted in a significantly greater recovery of multiple amounts of spiked HCC cells than the ASGPR+ selection (Ps < 0.05). The expression rates of either ASGPR or CPS1 were different in various liver cancer cell lines, ranging between 18% and 99% for ASGPR and between 9% and 98% for CPS1. In both human HCC tissues and liver cancer cell lines, there were a few HCC cells that did not stain positive for ASGPR or CPS1. The mixture of monoclonal antibodies against ASGPR and CPS1 identified more HCC cells than either antibody alone. However, these antibodies did not detect any tumor cells in blood samples spiked with the human breast cancer cell line MCF-7 and the human renal cancer cell line A498. ASGPR+ or/and CPS1+ CTCs were detected in 29

  4. Cell size control in bacteria.

    PubMed

    Chien, An-Chun; Hill, Norbert S; Levin, Petra Anne

    2012-05-01

    Like eukaryotes, bacteria must coordinate division with growth to ensure cells are the appropriate size for a given environmental condition or developmental fate. As single-celled organisms, nutrient availability is one of the strongest influences on bacterial cell size. Classic physiological experiments conducted over four decades ago first demonstrated that cell size is directly correlated with nutrient source and growth rate in the Gram-negative bacterium Salmonella typhimurium. This observation subsequently served as the basis for studies revealing a role for cell size in cell cycle progression in a closely related organism, Escherichia coli. More recently, the development of powerful genetic, molecular, and imaging tools has allowed us to identify and characterize the nutrient-dependent pathway responsible for coordinating cell division and cell size with growth rate in the Gram-positive model organism Bacillus subtilis. Here, we discuss the role of cell size in bacterial growth and development and propose a broadly applicable model for cell size control in this important and highly divergent domain of life.

  5. Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

    PubMed Central

    Swierk, John R.; Méndez-Hernández, Dalvin D.; McCool, Nicholas S.; Liddell, Paul; Terazono, Yuichi; Pahk, Ian; Tomlin, John J.; Oster, Nolan V.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens; Mallouk, Thomas E.

    2015-01-01

    Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed. PMID:25583488

  6. Enhanced photovoltaic performance and time varied controllable growth of a CuS nanoplatelet structured thin film and its application as an efficient counter electrode for quantum dot-sensitized solar cells via a cost-effective chemical bath deposition.

    PubMed

    Thulasi-Varma, Chebrolu Venkata; Rao, S Srinivasa; Kumar, Challa Shesha Sai Pavan; Gopi, Chandu V V M; Durga, I Kanaka; Kim, Soo-Kyoung; Punnoose, Dinah; Kim, Hee-Je

    2015-11-28

    also be a cost-effective way to fabricate flexible electrodes in dye-sensitized solar cells or supercapacitor applications.

  7. Enhanced photovoltaic performance and time varied controllable growth of a CuS nanoplatelet structured thin film and its application as an efficient counter electrode for quantum dot-sensitized solar cells via a cost-effective chemical bath deposition.

    PubMed

    Thulasi-Varma, Chebrolu Venkata; Rao, S Srinivasa; Kumar, Challa Shesha Sai Pavan; Gopi, Chandu V V M; Durga, I Kanaka; Kim, Soo-Kyoung; Punnoose, Dinah; Kim, Hee-Je

    2015-11-28

    also be a cost-effective way to fabricate flexible electrodes in dye-sensitized solar cells or supercapacitor applications. PMID:26497705

  8. Max-Plus Stochastic Control and Risk-Sensitivity

    SciTech Connect

    Fleming, Wendell H.; Kaise, Hidehiro; Sheu, Shuenn-Jyi

    2010-08-15

    In the Maslov idempotent probability calculus, expectations of random variables are defined so as to be linear with respect to max-plus addition and scalar multiplication. This paper considers control problems in which the objective is to minimize the max-plus expectation of some max-plus additive running cost. Such problems arise naturally as limits of some types of risk sensitive stochastic control problems. The value function is a viscosity solution to a quasivariational inequality (QVI) of dynamic programming. Equivalence of this QVI to a nonlinear parabolic PDE with discontinuous Hamiltonian is used to prove a comparison theorem for viscosity sub- and super-solutions. An example from mathematical finance is given, and an application in nonlinear H-infinity control is sketched.

  9. Multiple chemical sensitivity: controlled scientific studies as proof of causation.

    PubMed

    Tollefson, L

    1993-08-01

    Multiple chemical sensitivity is an environmental illness that demands exacting methods of diagnosis. Proposed associations between symptoms and specific substances, whether to one substance or to multiple chemicals, need to be critically examined through adequately designed scientific studies. Appropriate methods for controlled scientific study of adverse reactions to chemicals are discussed as well as the Food and Drug Administration's (FDA's) experience with aspartame as an example of the need for controlled scientific studies to refute or confirm anecdotal evidence. Since 1986 the FDA has received reports of 265 cases of epileptic seizures temporally associated with the ingestion of aspartame. Information obtained from the complainants' medical records as well as data on consumption patterns, temporal relationships, and challenge tests do not support the claim that the occurrences of the seizures are linked to consumption of aspartame. In addition, two double-blind, placebo-controlled crossover studies failed to demonstrate an association between epileptic seizures in children and adults and the ingestion of aspartame.

  10. Control of a mechanical aeration process via topological sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Abdelwahed, M.; Hassine, M.; Masmoudi, M.

    2009-06-01

    The topological sensitivity analysis method gives the variation of a criterion with respect to the creation of a small hole in the domain. In this paper, we use this method to control the mechanical aeration process in eutrophic lakes. A simplified model based on incompressible Navier-Stokes equations is used, only considering the liquid phase, which is the dominant one. The injected air is taken into account through local boundary conditions for the velocity, on the injector holes. A 3D numerical simulation of the aeration effects is proposed using a mixed finite element method. In order to generate the best motion in the fluid for aeration purposes, the optimization of the injector location is considered. The main idea is to carry out topological sensitivity analysis with respect to the insertion of an injector. Finally, a topological optimization algorithm is proposed and some numerical results, showing the efficiency of our approach, are presented.

  11. Brief overview of dye-sensitized solar cells.

    PubMed

    Hagfeldt, Anders

    2012-01-01

    Dye-sensitized solar cells (DSC) are based on molecular and nanometer-scale components. Record cell efficiencies of 12%, promising stability data and means of energy-efficient production methods have been accomplished. As selling points for the DSC technology the prospect of low-cost investments and fabrication are key features. DSCs offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. The basic principles of the operation of DSC, the state-of-the-art as well as the potentials for future development are described.

  12. Dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers.

    PubMed

    Mathew, Simon; Yella, Aswani; Gao, Peng; Humphry-Baker, Robin; Curchod, Basile F E; Ashari-Astani, Negar; Tavernelli, Ivano; Rothlisberger, Ursula; Nazeeruddin, Md Khaja; Grätzel, Michael

    2014-03-01

    Dye-sensitized solar cells have gained widespread attention in recent years because of their low production costs, ease of fabrication and tunable optical properties, such as colour and transparency. Here, we report a molecularly engineered porphyrin dye, coded SM315, which features the prototypical structure of a donor-π-bridge-acceptor and both maximizes electrolyte compatibility and improves light-harvesting properties. Linear-response, time-dependent density functional theory was used to investigate the perturbations in the electronic structure that lead to improved light harvesting. Using SM315 with the cobalt(II/III) redox shuttle resulted in dye-sensitized solar cells that exhibit a high open-circuit voltage VOC of 0.91 V, short-circuit current density JSC of 18.1 mA cm(-2), fill factor of 0.78 and a power conversion efficiency of 13%.

  13. Dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers

    NASA Astrophysics Data System (ADS)

    Mathew, Simon; Yella, Aswani; Gao, Peng; Humphry-Baker, Robin; Curchod, Basile F. E.; Ashari-Astani, Negar; Tavernelli, Ivano; Rothlisberger, Ursula; Nazeeruddin, Md. Khaja; Grätzel, Michael

    2014-03-01

    Dye-sensitized solar cells have gained widespread attention in recent years because of their low production costs, ease of fabrication and tunable optical properties, such as colour and transparency. Here, we report a molecularly engineered porphyrin dye, coded SM315, which features the prototypical structure of a donor-π-bridge-acceptor and both maximizes electrolyte compatibility and improves light-harvesting properties. Linear-response, time-dependent density functional theory was used to investigate the perturbations in the electronic structure that lead to improved light harvesting. Using SM315 with the cobalt(II/III) redox shuttle resulted in dye-sensitized solar cells that exhibit a high open-circuit voltage VOC of 0.91 V, short-circuit current density JSC of 18.1 mA cm-2, fill factor of 0.78 and a power conversion efficiency of 13%.

  14. Dye-sensitized Solar Cells for Solar Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Roy, M. S.; Deol, Y. S.; Kumar, Manish; Prasad, Narottam; Janu, Yojana

    2011-10-01

    Dye-sensitized solar cells (DSSCs) also known as Gratzel cells, have attracted the interests of researchers to a great extent because of its cost effective and easy manufacturing process without involving highly sophisticated lithographic technique and high cost raw materials as usually seen in conventional solar cell. Based on simple photo-electrochemical process, it has got immense potential in converting solar energy to electrical power in remote and desert area where the supply of conventional power is not possible. The overall peak power-production efficiency of dye-sensitized solar cells has been reported around 11 percent, so they are best suited to low-density applications and the price-to-performance ratio obtained through these solar cells is superior to others. DSSCs have ability to absorb even diffused sunlight and therefore work in cloudy whether as well without much impact over the efficiency. The present communication deals with a review of our work on DSSCs wherein we have used cost effective natural dyes/pigments as a sensitizer of nc-TiO2 and discussed about various key factors affecting the conversion efficiency of DSSC.

  15. Cell biology. Metabolic control of cell death.

    PubMed

    Green, Douglas R; Galluzzi, Lorenzo; Kroemer, Guido

    2014-09-19

    Beyond their contribution to basic metabolism, the major cellular organelles, in particular mitochondria, can determine whether cells respond to stress in an adaptive or suicidal manner. Thus, mitochondria can continuously adapt their shape to changing bioenergetic demands as they are subjected to quality control by autophagy, or they can undergo a lethal permeabilization process that initiates apoptosis. Along similar lines, multiple proteins involved in metabolic circuitries, including oxidative phosphorylation and transport of metabolites across membranes, may participate in the regulated or catastrophic dismantling of organelles. Many factors that were initially characterized as cell death regulators are now known to physically or functionally interact with metabolic enzymes. Thus, several metabolic cues regulate the propensity of cells to activate self-destructive programs, in part by acting on nutrient sensors. This suggests the existence of "metabolic checkpoints" that dictate cell fate in response to metabolic fluctuations. Here, we discuss recent insights into the intersection between metabolism and cell death regulation that have major implications for the comprehension and manipulation of unwarranted cell loss.

  16. Targeting Bcl-2 stability to sensitize cells harboring oncogenic ras.

    PubMed

    Peng, Bo; Ganapathy, Suthakar; Shen, Ling; Huang, Junchi; Yi, Bo; Zhou, Xiaodong; Dai, Wei; Chen, Changyan

    2015-09-01

    The pro-survival factor Bcl-2 and its family members are critical determinants of the threshold of the susceptibility of cells to apoptosis. Studies are shown that cells harboring an oncogenic ras were extremely sensitive to the inhibition of protein kinase C (PKC) and Bcl-2 could antagonize this apoptotic process. However, it remains unrevealed how Bcl-2 is being regulated in this apoptotic process. In this study, we investigate the role of Bcl-2 stability in sensitizing the cells harboring oncogenic K-ras to apoptosis triggered by PKC inhibitor GO6976. We demonstrated that Bcl-2 in Swiss3T3 cells ectopically expressing or murine lung cancer LKR cells harboring K-ras rapidly underwent ubiquitin-dependent proteasome pathway after the treatment of GO6976, accompanied with induction of apoptosis. In this process, Bcl-2 formed the complex with Keap-1 and Cul3. The mutation of serine-17 and deletion of BH-2 or 4 was required for Bcl-2 ubiquitination and degradation, which elevate the signal threshold for the induction of apoptosis in the cells following PKC inhibition. Thus, Bcl-2 appears an attractive target for the induction of apoptosis by PKC inhibition in cancer cells expressing oncogenic K-ras. PMID:26041886

  17. Endometriosis is associated with central sensitization: a psychophysical controlled study.

    PubMed

    Bajaj, Prem; Bajaj, Priti; Madsen, Hans; Arendt-Nielsen, Lars

    2003-09-01

    Endometriosis is a pain syndrome representing a major cause of pelvic pain in women of reproductive age. The aim of this study was to test the hypothesis that persistent nociceptive input from endometriotic tissues leads to central sensitization manifested by somatic hyperalgesia and increased referred pain areas to experimental saline-induced muscle pain in patients with endometriosis, compared to healthy control subjects. Ten women with laparoscopically confirmed endometriosis and 10 healthy, age-matched women participated in the study. Hypertonic saline (0.5 mL, 5.8%) was injected intramuscularly, in random succession, into 1 site of menstrual pain referral (the multifidus muscle at the low back) and into 1 non-pain control site (first dorsal interosseous muscle [FDI] of the hand). The post-saline pain intensity and pain areas at the FDI were significantly greater in patients with endometriosis than in control subjects (P <.05) but were not different between the groups for the back. An absence of enhancement of post-saline pain responses at the back in the endometriosis group suggests that saline-induced pain at the back appears to activate segmental inhibitory systems in patients with endometriosis. Manifestation of central sensitization in women with endometriosis is demonstrated by increased muscle nociceptor input in the form of increased post-saline pain intensity, pain areas at the FDI, and hypersensitivity to pressure stimulation. These findings provide new insights into the complex pain mechanisms associated with endometriosis.

  18. Asymmetric Zinc Phthalocyanines as Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Tunc, Gulenay; Yavuz, Yunus; Gurek, Aysegul; Canimkurbey, Betul; Kosemen, Arif; San, Sait Eren; Ahsen, Vefa

    Dye-sensitized solar cells (DSSCs) have received increasing attention due to their high incident to photon efficiency, easy fabrication and low production cost . Tremendous research efforts have been devoted to the development of new and efficient sensitizers suitable for practical use. In TiO2-based DSSCs, efficiencies of up to 11.4% under simulated sunlight have been obtained with rutheniumepolypyridyl complexes. However, the main drawback of ruthenium complexes is the lack of absorption in the red region of the visible light and the high cost. For this reason, dyes with large and stable p-conjugated systems such as porphyrins and phthalocyanines are important classes of potential sensitizers for highly efficient DSSCs. Phthalocyanines (Pcs) have been widely used as sensitizers because of their improved light-harvesting properties in the far red- and near-IR spectral regions and their extraordinary robustness [1]. In this work, a series of asymmetric Zn(II) Pcs bearing a carboxylic acid group and six hexylthia groups either at the peripheral or non-peripheral positions have been designed and synthesized to investigate the influence of the COOH group and the positions of hexylthia groups on the dye-sensitized solar cell (DSSC) performance.

  19. Vegetable-based dye-sensitized solar cells.

    PubMed

    Calogero, Giuseppe; Bartolotta, Antonino; Di Marco, Gaetano; Di Carlo, Aldo; Bonaccorso, Francesco

    2015-05-21

    There is currently a large effort to improve the performance of low cost renewable energy devices. Dye-sensitized solar cells (DSSCs) are emerging as one of the most promising low cost photovoltaic technologies, addressing "secure, clean and efficient solar energy conversion". Vegetable dyes, extracted from algae, flowers, fruit and leaves, can be used as sensitizers in DSSCs. Thus far, anthocyanin and betalain extracts together with selected chlorophyll derivatives are the most successful vegetable sensitizers. This review analyses recent progress in the exploitation of vegetable dyes for solar energy conversion and compares them to the properties of synthetic dyes. We provide an in-depth discussion on the main limitation of cell performance e.g. dye degradation, effective electron injection from the dye into the conduction band of semiconducting nanoparticles, such as titanium dioxide and zinc oxide, outlining future developments for the use of vegetable sensitizers in DSSCs. We also discuss the cost of vegetable dyes and how their versatility can boost the advancement of new power management solutions, especially for their integration in living environments, making the practical application of such systems economically viable. Finally, we present our view on future prospects in the development of synthetic analogues of vegetable dyes as sensitizers in DSSCs.

  20. Soluble extracellular Klotho decreases sensitivity to cigarette smoke induced cell death in human lung epithelial cells.

    PubMed

    Blake, David J; Reese, Caitlyn M; Garcia, Mario; Dahlmann, Elizabeth A; Dean, Alexander

    2015-10-01

    Chronic obstructive pulmonary disease (COPD) is currently the third leading cause of death in the US and is associated with an abnormal inflammatory response to cigarette smoke (CS). Exposure to CS induces oxidative stress and can result in cellular senescence in the lung. Cellular senescence can then lead to decreased proliferation of epithelial cells, the destruction of alveolar structure and pulmonary emphysema. The anti-aging gene, klotho, encodes a membrane bound protein that has been shown to be a key regulator of oxidative stress and cellular senescence. In this study the role of Klotho (KL) with regard to oxidative stress and cellular senescence was investigated in human pulmonary epithelial cells exposed to cigarette smoke. Individual clones that stably overexpress Klotho were generated through retroviral transfection and geneticin selection. Klotho overexpression was confirmed through RT-qPCR, Western blotting and ELISA. Compared to control cells, constitutive Klotho overexpression resulted in decreased sensitivity to cigarette smoke induced cell death in vitro via a reduction of reactive oxygen species and a decrease in the expression of p21. Our results suggest that increasing Klotho level in pulmonary epithelial cells may be a promising strategy to reduce cellular senescence and mitigate the risk for the development of COPD.

  1. A requirement for trypsin-sensitive cell-surface components for cell-cell interactions of embryonic neural retina cells

    PubMed Central

    McClay, DR; Godding, LR; Fransen, ME

    1977-01-01

    A quantitative assay was used to measure the rate of collection of a population of embryonic neural retina cells to the surface of cell aggregates. The rate of collection of freshly trysinized cells was limited in the initial stages by the rate of replacement of trypsin-sensitive cell- surface components. When cells were preincubated, or "recovered," and then added to cell aggregates, collection occurred at a linear rate and was independent of protein and glycoprotein synthesis. The adhesion of recovered cells was temperature and energy dependent, and was reversibly inhibited by cytochalasin B. Colchicine had little effect on collection of recovered cells. Antiserum directed against recovered cell membranes was shown to bind to recovered cells by indirect immunofluorescence. The antiserum also was shown to inhibit collection of recovered cells to aggregates, suggesting that at least some of the antigens identified might be involved in the adhesion process. The inhibitory effect of the antiserum was dose dependent . Freshly trypsinized cells absorbed neither the immunofluorescence activity nor the adhesion-inhibiting activity. Recovered cells absorbed away both activities. In specificity studies, dorsal neural retina cells adhered to aggregates of ventral optic tectum in preference to aggregates of dorsal optic tectum. The adhesive specificity of the dorsal retina cells was less sensitive to trypsin than the adhesive specificity of ventral retina cells which adhered preferentially to dorsal tectal aggregates only after a period of recovery. PMID:562349

  2. IAP antagonists sensitize murine osteosarcoma cells to killing by TNFα

    PubMed Central

    Shekhar, Tanmay M.; Miles, Mark A.; Gupte, Ankita; Taylor, Scott; Tascone, Brianna; Walkley, Carl R.; Hawkins, Christine J.

    2016-01-01

    Outcomes for patients diagnosed with the bone cancer osteosarcoma have not improved significantly in the last four decades. Only around 60% of patients and about a quarter of those with metastatic disease survive for more than five years. Although DNA-damaging chemotherapy drugs can be effective, they can provoke serious or fatal adverse effects including cardiotoxicity and therapy-related cancers. Better and safer treatments are therefore needed. We investigated the anti-osteosarcoma activity of IAP antagonists (also known as Smac mimetics) using cells from primary and metastatic osteosarcomas that arose spontaneously in mice engineered to lack p53 and Rb expression in osteoblast-derived cells. The IAP antagonists SM-164, GDC-0152 and LCL161, which efficiently target XIAP and cIAPs, sensitized cells from most osteosarcomas to killing by low levels of TNFα but not TRAIL. RIPK1 expression levels and activity correlated with sensitivity. RIPK3 levels varied considerably between tumors and RIPK3 was not required for IAP antagonism to sensitize osteosarcoma cells to TNFα. IAP antagonists, including SM-164, lacked mutagenic activity. These data suggest that drugs targeting XIAP and cIAP1/2 may be effective for osteosarcoma patients whose tumors express abundant RIPK1 and contain high levels of TNFα, and would be unlikely to provoke therapy-induced cancers in osteosarcoma survivors. PMID:27129149

  3. Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites.

    PubMed

    Shaikh, Sohel; Birdi, Anil; Qutubuddin, Syed; Lakatosh, Eric; Baskaran, Harihara

    2007-12-01

    Polydimethyl siloxane (PDMS) based pressure sensitive adhesives (PSA) incorporating organo-clays at different loadings were fabricated via solution casting. Partially exfoliated nanocomposites were obtained for the hydroxyl terminated PDMS in ethyl acetate solvent as determined by X-ray diffraction and atomic force microscopy. Drug release studies showed that the initial burst release was substantially reduced and the drug release could be controlled by the addition of organo-clay. Shear strength and shear adhesion failure temperature (SAFT) measurements indicated substantial improvement in adhesive properties of the PSA nanocomposite adhesives. Shear strength showed more than 200% improvement at the lower clay loadings and the SAFT increased by about 21% due to the reinforcement provided by the nano-dispersed clay platelets. It was found that by optimizing the level of the organosilicate additive to the polymer matrix, superior control over drug release kinetics and simultaneous improvements in adhesive properties could be attained for a transdermal PSA formulation. PMID:17786555

  4. ISway: a sensitive, valid and reliable measure of postural control

    PubMed Central

    2012-01-01

    Background Clinicians need a practical, objective test of postural control that is sensitive to mild neurological disease, shows experimental and clinical validity, and has good test-retest reliability. We developed an instrumented test of postural sway (ISway) using a body-worn accelerometer to offer an objective and practical measure of postural control. Methods We conducted two separate studies with two groups of subjects. Study I: sensitivity and experimental concurrent validity. Thirteen subjects with early, untreated Parkinson’s disease (PD) and 12 age-matched control subjects (CTR) were tested in the laboratory, to compare sway from force-plate COP and inertial sensors. Study II: test-retest reliability and clinical concurrent validity. A different set of 17 early-to-moderate, treated PD (tested ON medication), and 17 age-matched CTR subjects were tested in the clinic to compare clinical balance tests with sway from inertial sensors. For reliability, the sensor was removed, subjects rested for 30 min, and the protocol was repeated. Thirteen sway measures (7 time-domain, 5 frequency-domain measures, and JERK) were computed from the 2D time series acceleration (ACC) data to determine the best metrics for a clinical balance test. Results Both center of pressure (COP) and ACC measures differentiated sway between CTR and untreated PD. JERK and time-domain measures showed the best test-retest reliability (JERK ICC was 0.86 in PD and 0.87 in CTR; time-domain measures ICC ranged from 0.55 to 0.84 in PD and from 0.60 to 0.89 in CTR). JERK, all but one time-domain measure, and one frequency measure were significantly correlated with the clinical postural stability score (r ranged from 0.50 to 0.63, 0.01 < p < 0.05). Conclusions Based on these results, we recommend a subset of the most sensitive, reliable, and valid ISway measures to characterize posture control in PD: 1) JERK, 2) RMS amplitude and mean velocity from the time-domain measures, and 3) centroidal

  5. Identification of a novel EGF-sensitive cell cycle checkpoint

    SciTech Connect

    Walker, Francesca . E-mail: francesca.walker@ludwig.edu.au; Zhang Huihua; Burgess, Antony W.

    2007-02-01

    The site of action of growth factors on mammalian cell cycle has been assigned to the boundary between the G1 and S phases. We show here that Epidermal Growth Factor (EGF) is also required for mitosis. BaF/3 cells expressing the EGFR (BaF/wtEGFR) synthesize DNA in response to EGF, but arrest in S-phase. We have generated a cell line (BaF/ERX) with defective downregulation of the EGFR and sustained activation of EGFR signalling pathways: these cells undergo mitosis in an EGF-dependent manner. The transit of BaF/ERX cells through G2/M strictly requires activation of EGFR and is abolished by AG1478. This phenotype is mimicked by co-expression of ErbB2 in BaF/wtEGFR cells, and abolished by inhibition of the EGFR kinase, suggesting that sustained signalling of the EGFR, through impaired downregulation of the EGFR or heterodimerization, is required for completion of the cycle. We have confirmed the role of EGFR signalling in the G2/M phase of the cell cycle using a human tumor cell line which overexpresses the EGFR and is dependent on EGFR signalling for growth. These findings unmask an EGF-sensitive checkpoint, helping to understand the link between sustained EGFR signalling, proliferation and the acquisition of a radioresistant phenotype in cancer cells.

  6. Simple Sensitivity Analysis for Orion Guidance Navigation and Control

    NASA Technical Reports Server (NTRS)

    Pressburger, Tom; Hoelscher, Brian; Martin, Rodney; Sricharan, Kumar

    2013-01-01

    The performance of Orion flight software, especially its GNC software, is being analyzed by running Monte Carlo simulations of Orion spacecraft flights. The simulated performance is analyzed for conformance with flight requirements, expressed as performance constraints. Flight requirements include guidance (e.g. touchdown distance from target) and control (e.g., control saturation) as well as performance (e.g., heat load constraints). The Monte Carlo simulations disperse hundreds of simulation input variables, for everything from mass properties to date of launch. We describe in this paper a sensitivity analysis tool ("Critical Factors Tool" or CFT) developed to find the input variables or pairs of variables which by themselves significantly influence satisfaction of requirements or significantly affect key performance metrics (e.g., touchdown distance from target). Knowing these factors can inform robustness analysis, can inform where engineering resources are most needed, and could even affect operations. The contributions of this paper include the introduction of novel sensitivity measures, such as estimating success probability, and a technique for determining whether pairs of factors are interacting dependently or independently. The tool found that input variables such as moments, mass, thrust dispersions, and date of launch were found to be significant factors for success of various requirements. Examples are shown in this paper as well as a summary and physics discussion of EFT-1 driving factors that the tool found.

  7. Sluggish and Brisk Ganglion Cells Detect Contrast With Similar Sensitivity

    PubMed Central

    Xu, Ying; Dhingra, Narender K.; Smith, Robert G.; Sterling, Peter

    2010-01-01

    Roughly half of all ganglion cells in mammalian retina belong to the broad class, termed “sluggish.” Many of these cells have small receptive fields and project via lateral geniculate nuclei to visual cortex. However, their possible contributions to perception have been largely ignored because sluggish cells seem to respond weakly compared with the more easily studied “brisk” cells. By selecting small somas under infrared DIC optics and recording with a loose seal, we could routinely isolate sluggish cells. When a spot was matched spatially and temporally to the receptive field center, most sluggish cells could detect the same low contrasts as brisk cells. Detection thresholds for the two groups determined by an “ideal observer” were similar: threshold contrast for sluggish cells was 4.7 ± 0.5% (mean ± SE), and for brisk cells was 3.4 ± 0.3% (Mann-Whitney test: P > 0.05). Signal-to-noise ratios for the two classes were also similar at low contrast. However, sluggish cells saturated at somewhat lower contrasts (contrast for half-maximum response was 14 ± 1 vs. 19 ± 2% for brisk cells) and were less sensitive to higher temporal frequencies (when the stimulus frequency was increased from 2 to 4 Hz, the response rate fell by 1.6-fold). Thus the sluggish cells covered a narrower dynamic range and a narrower temporal bandwidth, consistent with their reported lower information rates. Because information per spike is greater at lower firing rates, sluggish cells may represent “cheaper” channels that convey less urgent visual information at a lower energy cost. PMID:15601731

  8. Natural dyes as sensitizers to increase the efficiency in sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Cerda, Bayron; Sivakumar, R.; Paulraj, M.

    2016-05-01

    A dye-sensitized solar cell (DSSC) is a sandwich type solar cell consisting of a photoelectrode, a counter electrode and a liquid electrolyte. The photo electrode comprises of a titanium dioxide semiconducting thin film grown over a glass substrate which in-turn has a transparent thin conducting layer of tin oxide film doped with fluorine (FTO) coated over it. The aim of this work is to develop photoelectrodes with different dyes to increase the efficiency of this type of solar cells. Dyes obtained from fresh sources of maqui, black myrtle, spinach and a dye mixture of spinach and spinach-maqui-myrtle were used. The technique used for the extraction of the dyes was maceration for one day, in methanol. Colourants and photoelectrodes were studied using, UV-vis spectrophotometer for their spectral properties. Their photovoltaic properties such as efficiency, fill factor, open circuit voltage and short circuit current were studied using a solar simulator and source meter unit.

  9. Nuclear PTEN controls DNA repair and sensitivity to genotoxic stress

    PubMed Central

    Bassi, C; Ho, J; Srikumar, T; Dowling, RJO; Gorrini, C; Miller, SJ; Mak, TW; Neel, BG; Raught, B; Stambolic, V

    2016-01-01

    Loss of function of the Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene is associated with many human cancers. In the cytoplasm, PTEN antagonizes the Phosphatidylinositol 3′ kinase (PI3K) signaling pathway. PTEN also accumulates in the nucleus, where its function remains poorly understood. We demonstrate that SUMOylation (SUMO) of PTEN controls its nuclear localization. In cells exposed to genotoxic stress, SUMO-PTEN was rapidly excluded from the nucleus dependent on the protein kinase Ataxia telangiectasia mutated (ATM). Cells lacking nuclear PTEN were hypersensitive to DNA damage, while PTEN-deficient cells were susceptible to killing by a combination of genotoxic stress and a small molecule PI3K inhibitor both in vitro and in vivo. Our findings may have implications for individualized therapy for patients with PTEN-deficient tumors. PMID:23888040

  10. Ligand Engineering for the Efficient Dye-Sensitized Solar Cells with Ruthenium Sensitizers and Cobalt Electrolytes.

    PubMed

    Aghazada, Sadig; Gao, Peng; Yella, Aswani; Marotta, Gabriele; Moehl, Thomas; Teuscher, Joël; Moser, Jacques-E; De Angelis, Filippo; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2016-07-01

    Over the past 20 years, ruthenium(II)-based dyes have played a pivotal role in turning dye-sensitized solar cells (DSCs) into a mature technology for the third generation of photovoltaics. However, the classic I3(-)/I(-) redox couple limits the performance and application of this technique. Simply replacing the iodine-based redox couple by new types like cobalt(3+/2+) complexes was not successful because of the poor compatibility between the ruthenium(II) sensitizer and the cobalt redox species. To address this problem and achieve higher power conversion efficiencies (PCEs), we introduce here six new cyclometalated ruthenium(II)-based dyes developed through ligand engineering. We tested DSCs employing these ruthenium(II) complexes and achieved PCEs of up to 9.4% using cobalt(3+/2+)-based electrolytes, which is the record efficiency to date featuring a ruthenium-based dye. In view of the complicated liquid DSC system, the disagreement found between different characterizations enlightens us about the importance of the sensitizer loading on TiO2, which is a subtle but equally important factor in the electronic properties of the sensitizers. PMID:27322854

  11. Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent

    PubMed Central

    Lee, Jin-Wook; Son, Dae-Yong; Ahn, Tae Kyu; Shin, Hee-Won; Kim, In Young; Hwang, Seong-Ju; Ko, Min Jae; Sul, Soohwan; Han, Hyouksoo; Park, Nam-Gyu

    2013-01-01

    The reported photocurrent density (JSC) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/cm2 despite the capability to generate 38 mA/cm2, which results from inefficient electron injection and fast charge recombination. Here, we report on a PbS:Hg QD-sensitized solar cell with an unprecedentedly high JSC of 30 mA/cm2. By Hg2+ doping into PbS, JSC is almost doubled with improved stability. Femtosecond transient study confirms that the improved JSC is due to enhanced electron injection and suppressed charge recombination. EXAFS reveals that Pb-S bond is reinforced and structural disorder is reduced by interstitially incorporated Hg2+, which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high JSC, power conversion efficiency of 5.6% is demonstrated at one sun illumination. PMID:23308343

  12. Pressure sensitive multifunctional solar cells using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Somani, Prakash R.

    2010-04-01

    A unique multifunctional device combining the photovoltaic action and pressure sensitivity is demonstrated which is based on the heterojunction of n-Si and carbon nanotubes (double walled carbon nanotubes or multiwalled carbon nanotubes) and using copper phthalocyanine surface modified indium-tin-oxide electrode and shows pressure dependent photovoltaic action. The device can work as a solar cell, pressure sensor, or photovoltaic pressure sensor. Such multifunctional organic/organic-inorganic hybrid solar cells are expected to find many applications in the near future.

  13. Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells.

    PubMed

    Cherrington, Ruth; Wood, Benjamin Michael; Salaoru, Iulia; Goodship, Vannessa

    2016-05-04

    Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 µm thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm(2) and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 °C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 ˚C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

  14. Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells.

    PubMed

    Cherrington, Ruth; Wood, Benjamin Michael; Salaoru, Iulia; Goodship, Vannessa

    2016-01-01

    Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 µm thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm(2) and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 °C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 ˚C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells. PMID:27166761

  15. Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

    PubMed Central

    Cherrington, Ruth; Wood, Benjamin Michael; Salaoru, Iulia; Goodship, Vannessa

    2016-01-01

    Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 µm thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 °C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 ˚C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells. PMID:27166761

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  17. Addiction: Decreased reward sensitivity and increased expectation sensitivity conspire to overwhelm the brain's control circuit

    PubMed Central

    Volkow, Nora D.; Wang, Gene-Jack; Fowler, Joanna S.; Tomasi, Dardo; Telang, Frank; Baler, Ruben

    2010-01-01

    Based on brain imaging findings, we present a model according to which addiction emerges as an imbalance in the information processing and integration among various brain circuits and functions. The dysfunctions reflect (a) decreased sensitivity of reward circuits, (b) enhanced sensitivity of memory circuits to conditioned expectations to drugs and drug cues, stress reactivity, and (c) negative mood, and a weakened control circuit. Although initial experimentation with a drug of abuse is largely a voluntary behavior, continued drug use can eventually impair neuronal circuits in the brain that are involved in free will, turning drug use into an automatic compulsive behavior. The ability of addictive drugs to co-opt neuro-transmitter signals between neurons (including dopamine, glutamate, and GABA) modifies the function of different neuronal circuits, which begin to falter at different stages of an addiction trajectory. Upon exposure to the drug, drug cues or stress this results in unrestrained hyperactivation of the motivation/drive circuit that results in the compulsive drug intake that characterizes addiction. PMID:20730946

  18. Influence of Ancillary Ligands in Dye-Sensitized Solar Cells.

    PubMed

    Pashaei, Babak; Shahroosvand, Hashem; Graetzel, Michael; Nazeeruddin, Mohammad Khaja

    2016-08-24

    Dye-sensitized solar cells (DSSCs) have motivated many researchers to develop various sensitizers with tailored properties involving anchoring and ancillary ligands. Ancillary ligands carry favorable light-harvesting abilities and are therefore crucial in determining the overall power conversion efficiencies. The use of ancillary ligands having aliphatic chains and/or π-extended aromatic units decreases charge recombination and permits the collection of a large fraction of sunlight. This review aims to provide insight into the relationship between ancillary ligand structure and DSSC properties, which can further guide the function-oriented design and synthesis of different sensitizers for DSSCs. This review outlines how the new and rapidly expanding class of chelating ancillary ligands bearing 2,2'-bipyridyl, 1,10-phenanthroline, carbene, dipyridylamine, pyridyl-benzimidazole, pyridyl-azolate, and other aromatic ligands provides a conduit for potentially enhancing the performance and stability of DSSCs. Finally, these classes of Ru polypyridyl complexes have gained increasing interest for feasible large-scale commercialization of DSSCs due to their more favorable light-harvesting abilities and long-term thermal and chemical stabilities compared with other conventional sensitizers. Therefore, the main idea is to inspire readers to explore new avenues in the design of new sensitizers for DSSCs based on different ancillary ligands. PMID:27479482

  19. Sensitizers containing donor cascade and rhodanine-3-acetic acid moieties for dye-sensitized solar cells

    SciTech Connect

    Wu, Quan-Ping; Zhang, Lu; Liang, Mao; Sun, Zhe; Xue, Song

    2011-01-15

    Three organic dyes with D-{pi}-D-{pi}-A structure based on triarylamine, dimethylarylamine, and rhodanine-3-acetic acid moieties are designed and synthesized. Incorporating thiophene moieties into the system affords sensitizers with high molar extinction coefficients. These dyes were applied into nanocrystalline TiO{sub 2} dye-sensitized solar cells through standard operations. For a typical device the maximal monochromatic incident photon-to-current conversion efficiency (IPCE) can reach 73%, with a short-circuit photocurrent density (J{sub sc}) of 7.3 mA/cm{sup 2}, an open-circuit voltage (V{sub oc}) of 636 mV, and a fill factor (ff) of 0.61, corresponding to an overall conversion efficiency ({eta}) of 2.86%. (author)

  20. A Role for Regulatory T Cells in a Murine Model of Epicutaneous Toluene Diisocyanate Sensitization.

    PubMed

    Long, Carrie Mae; Marshall, Nikki B; Lukomska, Ewa; Kashon, Michael L; Meade, B Jean; Shane, Hillary; Anderson, Stacey E

    2016-07-01

    Toluene diisocyanate (TDI) is a leading cause of chemical-induced occupational asthma which impacts workers in a variety of industries worldwide. Recently, the robust regulatory potential of regulatory T cells (Tregs) has become apparent, including their functional role in the regulation of allergic disease; however, their function in TDI-induced sensitization has not been explored. To elucidate the kinetics, phenotype, and function of Tregs during TDI sensitization, BALB/c mice were dermally exposed (on each ear) to a single application of TDI (0.5-4% v/v) or acetone vehicle and endpoints were evaluated via RT-PCR and flow cytometry. The draining lymph node (dLN) Treg population expanded significantly 4, 7, and 9 days after single 4% TDI exposure. This population was identified using a variety of surface and intracellular markers and was found to be phenotypically heterogeneous based on increased expression of markers including CD103, CCR6, CTLA4, ICOS, and Neuropilin-1 during TDI sensitization. Tregs isolated from TDI-sensitized mice were significantly more suppressive compared with their control counterparts, further supporting a functional role for Tregs during TDI sensitization. Last, Tregs were depleted prior to TDI sensitization and an intensified sensitization response was observed. Collectively, these data indicate that Tregs exhibit a functional role during TDI sensitization. Because the role of Tregs in TDI sensitization has not been previously elucidated, these data contribute to the understanding of the immunologic mechanisms of chemical induced allergic disease. PMID:27103660

  1. A Role for Regulatory T Cells in a Murine Model of Epicutaneous Toluene Diisocyanate Sensitization

    PubMed Central

    Long, Carrie Mae; Marshall, Nikki B.; Lukomska, Ewa; Kashon, Michael L.; Meade, B. Jean; Shane, Hillary; Anderson, Stacey E.

    2016-01-01

    Toluene diisocyanate (TDI) is a leading cause of chemical-induced occupational asthma which impacts workers in a variety of industries worldwide. Recently, the robust regulatory potential of regulatory T cells (Tregs) has become apparent, including their functional role in the regulation of allergic disease; however, their function in TDI-induced sensitization has not been explored. To elucidate the kinetics, phenotype, and function of Tregs during TDI sensitization, BALB/c mice were dermally exposed (on each ear) to a single application of TDI (0.5–4% v/v) or acetone vehicle and endpoints were evaluated via RT-PCR and flow cytometry. The draining lymph node (dLN) Treg population expanded significantly 4, 7, and 9 days after single 4% TDI exposure. This population was identified using a variety of surface and intracellular markers and was found to be phenotypically heterogeneous based on increased expression of markers including CD103, CCR6, CTLA4, ICOS, and Neuropilin-1 during TDI sensitization. Tregs isolated from TDI-sensitized mice were significantly more suppressive compared with their control counterparts, further supporting a functional role for Tregs during TDI sensitization. Last, Tregs were depleted prior to TDI sensitization and an intensified sensitization response was observed. Collectively, these data indicate that Tregs exhibit a functional role during TDI sensitization. Because the role of Tregs in TDI sensitization has not been previously elucidated, these data contribute to the understanding of the immunologic mechanisms of chemical induced allergic disease. PMID:27103660

  2. Oxidation of cell surface thiol groups by contact sensitizers triggers the maturation of dendritic cells.

    PubMed

    Kagatani, Saori; Sasaki, Yoshinori; Hirota, Morihiko; Mizuashi, Masato; Suzuki, Mie; Ohtani, Tomoyuki; Itagaki, Hiroshi; Aiba, Setsuya

    2010-01-01

    p38 mitogen-activated protein kinase (MAPK) has a crucial role in the maturation of dendritic cells (DCs) by sensitizers. Recently, it has been reported that the oxidation of cell surface thiols by an exogenous impermeant thiol oxidizer can phosphorylate p38 MAPK. In this study, we examined whether sensitizers oxidize cell surface thiols of monocyte-derived DCs (MoDCs). When cell surface thiols were quantified by flow cytometry using Alexa fluor maleimide, all the sensitizers that we examined decreased cell surface thiols on MoDCs. To examine the effects of decreased cell surface thiols by sensitizers on DC maturation, we analyzed the effects of an impermeant thiol oxidizer, o-phenanthroline copper complex (CuPhen). The treatment of MoDCs with CuPhen decreased cell surface thiols, phosphorylated p38 MAPK, and induced MoDC maturation, that is, the augmentation of CD83, CD86, HLA-DR, and IL-8 mRNA, as well as the downregulation of aquaporin-3 mRNA. The augmentation of CD86 was significantly suppressed when MoDCs were pretreated with N-acetyl-L-cystein or treated with SB203580. Finally, we showed that epicutaneous application of 2,4-dinitrochlorobenzene on mouse skin significantly decreased cell surface thiols of Langerhans cells in vivo. These data suggest that the oxidation of cell surface thiols has some role in triggering DC maturation by sensitizers. PMID:19641517

  3. Insulin receptor substrate 1 expression enhances the sensitivity of 32D cells to chemotherapy-induced cell death

    SciTech Connect

    Porter, Holly A.; Carey, Gregory B.; Keegan, Achsah D.

    2012-08-15

    The adapters IRS1 and IRS2 link growth factor receptors to downstream signaling pathways that regulate proliferation and survival. Both suppress factor-withdrawal-induced apoptosis and have been implicated in cancer progression. However, recent studies suggest IRS1 and IRS2 mediate differential functions in cancer pathogenesis. IRS1 promoted breast cancer proliferation, while IRS2 promoted metastasis. The role of IRS1 and IRS2 in controlling cell responses to chemotherapy is unknown. To determine the role of IRS1 and IRS2 in the sensitivity of cells to chemotherapy, we treated 32D cells lacking or expressing IRS proteins with various concentrations of chemotherapeutic agents. We found that expression of IRS1, in contrast to IRS2, enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. When IRS2 was expressed with IRS1, the cells no longer showed enhanced sensitivity. Expression of IRS1 did not alter the expression of pro- and anti-apoptotic proteins; however, 32D-IRS1 cells expressed higher levels of Annexin A2. In 32D-IRS1 cells, IRS1 and Annexin A2 were both located in cytoplasmic and membrane fractions. We also found that IRS1 coprecipitated with Annexin A2, while IRS2 did not. Decreasing Annexin A2 levels reduced 32D-IRS1 cell sensitivity to chemotherapy. These results suggest IRS1 enhances sensitivity to chemotherapy in part through Annexin A2. -- Highlights: Black-Right-Pointing-Pointer IRS1 enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. Black-Right-Pointing-Pointer This sensitivity is abrogated by the expression of IRS2. Black-Right-Pointing-Pointer Expressing IRS1 in 32D cells increased levels of Annexin A2. Black-Right-Pointing-Pointer Both IRS1 and Annexin A2 were located in cytoplasmic and membrane fractions. Black-Right-Pointing-Pointer Decreasing Annexin A2 in 32D-IRS1 cells abated their sensitivity to chemotherapy.

  4. Monolithic-Structured Single-Layered Textile-Based Dye-Sensitized Solar Cells

    PubMed Central

    Yun, Min Ju; Cha, Seung I.; Kim, Han Seong; Seo, Seon Hee; Lee, Dong Y.

    2016-01-01

    Textile-structured solar cells are frequently discussed in the literature due to their prospective applications in wearable devices and in building integrated solar cells that utilize their flexibility, mechanical robustness, and aesthetic appearance, but the current approaches for textile-based solar cells—including the preparation of fibre-type solar cells woven into textiles—face several difficulties from high friction and tension during the weaving process. This study proposes a new structural concept and fabrication process for monolithic-structured textile-based dye-sensitized solar cells that are fabricated by a process similar to the cloth-making process, including the preparation of wires and yarns that are woven for use in textiles, printed, dyed, and packaged. The fabricated single-layered textile-based dye-sensitized solar cells successfully act as solar cells in our study, even under bending conditions. By controlling the inter-weft spacing and the number of Ti wires for the photoelectrode conductor, we have found that the performance of this type of dye-sensitized solar cell was notably affected by the spacing between photoelectrodes and counter-electrodes, the exposed areas of Ti wires to photoelectrodes, and photoelectrodes’ surface morphology. We believe that this study provides a process and concept for improved textile-based solar cells that can form the basis for further research. PMID:27708359

  5. Monolithic-Structured Single-Layered Textile-Based Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Yun, Min Ju; Cha, Seung I.; Kim, Han Seong; Seo, Seon Hee; Lee, Dong Y.

    2016-10-01

    Textile-structured solar cells are frequently discussed in the literature due to their prospective applications in wearable devices and in building integrated solar cells that utilize their flexibility, mechanical robustness, and aesthetic appearance, but the current approaches for textile-based solar cells—including the preparation of fibre-type solar cells woven into textiles—face several difficulties from high friction and tension during the weaving process. This study proposes a new structural concept and fabrication process for monolithic-structured textile-based dye-sensitized solar cells that are fabricated by a process similar to the cloth-making process, including the preparation of wires and yarns that are woven for use in textiles, printed, dyed, and packaged. The fabricated single-layered textile-based dye-sensitized solar cells successfully act as solar cells in our study, even under bending conditions. By controlling the inter-weft spacing and the number of Ti wires for the photoelectrode conductor, we have found that the performance of this type of dye-sensitized solar cell was notably affected by the spacing between photoelectrodes and counter-electrodes, the exposed areas of Ti wires to photoelectrodes, and photoelectrodes’ surface morphology. We believe that this study provides a process and concept for improved textile-based solar cells that can form the basis for further research.

  6. Guinea Pig Lung Lavage Cells After Intranasal BCG Sensitization

    PubMed Central

    Terai, T.; Ganguly, Rama; Waldman, Robert H.

    1979-01-01

    Recent studies have suggested that intranasal administration of antigen can induce local cell-mediated immunity in lung lavage cells. The present study was designed to examine the changes in composition of lung lavage cells and their capacity to produce the lymphokine migration inhibitory factor after intranasal immunization with BCG in guinea pigs. Results indicate that guinea pigs responded to respiratory tract BCG infection with an increase in immunocompetent cells in the bronchoalveolar tract and with production of migration inhibitory factor. After local pulmonary BCG administration, the total number of cells increased as compared with that of the uninfected animals, the increase being statistically significant within 2 weeks. This marked increase in the total cell population is due to a more than doubling of the number of macrophages in the lavage fluid. Animals also developed at this time positive delayed hypersensitivity to intradermally administered purified protein derivative. A significant increase in the total lymphoid cells and macrophage population was observed again at 6 weeks after sensitization, suggesting that the response is biphasic in nature. At 6 weeks, however, there was also a significant rise in total lymphocytes and T cell population in addition to macrophage numbers. This increase in T cells correlated with an increase in production of migration inhibitory factor in the presence of purified protein derivative. These data suggest that the immune response of the respiratory tract after BCG challenge involves increased recruitment of immunocompetent cells locally at the site of infection and that these cells are capable of producing effector molecules in terms of the elaboration of migration inhibitory factor. PMID:387595

  7. A comparison of hyperthermia cisplatin sensitization in human ovarian carcinoma and glioma cell lines sensitive and resistant to cisplatin treatment.

    PubMed

    Raaphorst, G P; Doja, S; Davis, L; Stewart, D; Ng, C E

    1996-01-01

    Two pairs of human tumor cell lines (glioma and ovarian carcinoma (OvCa) each having a parental cell line and cisplatin-resistant variant, were evaluated for (a) cisplatin response, (b) hyperthermia response, and (c) combined hyperthermia and cisplatin response. The two resistant lines had comparable resistant responses while for the parental lines, the OvCa was more sensitive than the glioma to cisplatin doses up to 14 microgram/ml. For the hyperthermia response, the OvCa parental line was more resistant than the variant line at low-temperature hyperthermia (41 degrees C or 42 degrees C) but became more sensitive at high temperature (45 degree C). For the glioma, the parental line was more sensitive to hyperthermia at all temperatures tested. Hyperthermia caused sensitization to cisplatin in all cell lines but was generally greater in the glioma cell lines. In the OvCa system, hyperthermia had a slightly greater sensitizing effect on the resistant cell lines, while in the glioma the opposite was true. The degree of sensitization increased with hyperthermia temperature. In summary, the results showed that there is no cross- resistance for hyperthermia and cisplatin, that the degree of thermal sensitization is not reduced in cisplatin- resistant cell lines, and that cisplatin thermal sensitization is cell-line and temperature dependent. Thus, hyperthermia can effectively improve tumor cell response to cisplatin and may be useful in overcoming resistance to cisplatin.

  8. Curcumin Sensitizes Silymarin to Exert Synergistic Anticancer Activity in Colon Cancer Cells.

    PubMed

    Montgomery, Amanda; Adeyeni, Temitope; San, KayKay; Heuertz, Rita M; Ezekiel, Uthayashanker R

    2016-01-01

    We studied combinatorial interactions of two phytochemicals, curcumin and silymarin, in their action against cancer cell proliferation. Curcumin is the major component of the spice turmeric. Silymarin is a bioactive component of milk thistle used as a protective supplement against liver disease. We studied antiproliferative effects of curcumin alone, silymarin alone and combinations of curcumin and silymarin using colon cancer cell lines (DLD-1, HCT116, LoVo). Curcumin inhibited colon cancer cell proliferation in a concentration-dependent manner, whereas silymarin showed significant inhibition only at the highest concentrations assessed. We found synergistic effects when colon cancer cells were treated with curcumin and silymarin together. The combination treatment led to inhibition of colon cancer cell proliferation and increased apoptosis compared to single compound treated cells. Combination treated cells exhibited marked cell rounding and membrane blebbing of apoptotic cells. Curcumin treated cells showed 3-fold more caspase3/7 activity whereas combination treated cells showed 5-fold more activity compared to control and silymarin treated cells. When DLD-1 cells were pre-exposed to curcumin, followed by treatment with silymarin, the cells underwent a high amount of cell death. The pre-exposure studies indicated curcumin sensitization of silymarin effect. Our results indicate that combinatorial treatments using phytochemicals are effective against colorectal cancer. PMID:27390600

  9. Curcumin Sensitizes Silymarin to Exert Synergistic Anticancer Activity in Colon Cancer Cells

    PubMed Central

    Montgomery, Amanda; Adeyeni, Temitope; San, KayKay; Heuertz, Rita M.; Ezekiel, Uthayashanker R.

    2016-01-01

    We studied combinatorial interactions of two phytochemicals, curcumin and silymarin, in their action against cancer cell proliferation. Curcumin is the major component of the spice turmeric. Silymarin is a bioactive component of milk thistle used as a protective supplement against liver disease. We studied antiproliferative effects of curcumin alone, silymarin alone and combinations of curcumin and silymarin using colon cancer cell lines (DLD-1, HCT116, LoVo). Curcumin inhibited colon cancer cell proliferation in a concentration-dependent manner, whereas silymarin showed significant inhibition only at the highest concentrations assessed. We found synergistic effects when colon cancer cells were treated with curcumin and silymarin together. The combination treatment led to inhibition of colon cancer cell proliferation and increased apoptosis compared to single compound treated cells. Combination treated cells exhibited marked cell rounding and membrane blebbing of apoptotic cells. Curcumin treated cells showed 3-fold more caspase3/7 activity whereas combination treated cells showed 5-fold more activity compared to control and silymarin treated cells. When DLD-1 cells were pre-exposed to curcumin, followed by treatment with silymarin, the cells underwent a high amount of cell death. The pre-exposure studies indicated curcumin sensitization of silymarin effect. Our results indicate that combinatorial treatments using phytochemicals are effective against colorectal cancer. PMID:27390600

  10. Bipyridyl cobalt complex mediators in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Scott, Michael J.

    Dye-sensitization of semiconductor substrates allows for efficient charge injection into the semiconductor conduction band. Dye-sensitized solar cells (DSSCs) exploit this for conversion of light into electrical energy. By employing mesoporous TiO2 a significant portion of visible light can be absorbed. The mesoporous TiO2, deposited on a transparent conducting oxide (TCO) medium, constitutes the photoanode of the DSSC. A wide range of materials may be used as a cathode. A redox electrolyte solution completes the cell. Typically, the I-/I3- redox couple has been employed in DSSCs. The use of bipyridyl cobalt complexes allows for tuning of the cell's electrochemistry, exploration of diverse cathode materials, and investigation of mediator solution additives. Cobalt complexes with alkyl, ester, and amide functionalities were considered throughout this body of work. The cobalt complexes were investigated on the basis of time dependence and electrode dependence. The cobalt complexes are stable for at least a period of one week when dissolved in gamma-butyrolactone. Gold, carbon and modified TCO cathodes perform well in cells employing the alkyl substituted complex. Gold cathodes alone provide the best performance with cells employing the ester and amide substituted complex. An optically transparent cathode was developed for use in stacked DSSCs, allowing light that is not absorbed by the first DSSC in a stack to be absorbed by a second cell. A spectrally complementary dye in the second cell extends the light absorption to longer wavelengths. Spatial current images were obtained to investigate the local current behavior of cobalt mediated cells. Intentional electrode damage was visualized, and the effects of increased pressure on the cell were discussed. The use of phenothiazine (PTZ) moieties as co-mediators in cobalt mediated DSSCs was investigated. An anionic PTZ salt was most effective at reducing the photo-oxidized sensitizing dye. This PTZ salt enhanced the

  11. Enhancement of Spectral Response of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Chang, Shuai

    Dye-Sensitized solar cell (DSSC) is a class of third-generation solar devices. A notable feature of DSSC is that it can be manufactured by solution-based approach; this non-vacuum processing renders significant reduction in manufacturing costs. Different from conventional solar cells, in a DSSC, mesoporous semiconductor film with large surface areas is utilized for anchoring dye molecules, serving as light absorbing layer. Dye sensitizers play an important role in determining the final performance in DSSCs. Since the first highly-efficient DSSC was reported in 1991 sensitized by a ruthenium-based dye, numerous researchers have been focused on the development and characterization of various kinds of dyes for the applications in DSSCs. These include mainly metal complexes dyes, organic dyes, porphyrins and phthalocyanines dyes. The first part of my thesis work is to develop and test new dyes for DSSCs and a series of phenothiazine-based organic dyes and new porphyrin dyes are reported during the process. It has been realized that extending the response of dye sensitizers to a wider range of the solar spectrum is a key step in further improving the device efficiency. Typically, there are two ways for expanding the strong spectral response of DSSCs from visible to far red/NIR region. One approach is called co-sensitization. Herein, we demonstrate a new co-sensitization concept where small molecules is used to insert the interstitial site of between the pre-adsorbed large molecules. In this case, the co-adsorbed small ones is found to improve the light response and impede the back recombination, finally leading to the power conversion efficiency over 10% in conventional DSSC devices and a record-equaling efficiency of 9.2% in quasi-solid-state devices. I also implemented graphene sheets in the anode films for better charge transfer efficiency and break the energy conversion limit of co-sensitization in DSSCs. The optimal configuration between porphyrin dyes and

  12. Expression of GITR Enhances Multiple Myeloma Cell Sensitivity to Bortezomib.

    PubMed

    Zhao, Yinghao; Zhang, Kun; Li, Guangquan; Zhang, Xingyi; Shi, Donglei

    2015-01-01

    Recently tumor necrosis factor receptor super family member 18 (TNFRSF18, also called GITR) has been identified as a novel tumor suppressor gene in Multiple Myeloma (MM), undergoing aberrant DNA methylation-mediated gene expression silencing. Furthermore, the expression of GITR blocks canonical NF-κB activation in MM cells in response to TNFα. Bortezomib, a proteasome inhibitor, can induce NF-κB activation, which may significantly influence the drug response in MM patients. In this study, we aim to elucidate if GITR status is associated with response to Bortezomib in MM cells through regulating GITR mediated NF-κB blockade. We found that GITR was significantly downregulated in MM patients and cell lines. Overexpression of GITR inhibited non-canonical NF-κB activation induced by TNFα. Moreover, NF-κB inhibitor induced apoptosis in GITR-deficient MM cells in response to TNFα. In addition, overexpression of GITR could inhibit Bortezomib-induced NF-κB activation and enhance the cytotoxicity of Bortezomib in GITR-deficient MM cell line (MM1.S). In contrast, knockdown of GITR attenuated the cytotoxic effect of Bortezomib on GITR proficient MM (RPMI) cell line and increased NF-κB activation. Finally, overexpression of GITR enhanced the sensitivity to Bortezomib in co-culture with bone marrow stromal cells and significantly reduced the tumor growth in MM1.S xenograft mice. In conclusion, we demonstrated that GITR expression can enhance the sensitivity to Bortezomib by inhibiting Bortezomib-induced NF-κB activation.

  13. miR-25 modulates NSCLC cell radio-sensitivity through directly inhibiting BTG2 expression

    SciTech Connect

    He, Zhiwei Liu, Yi Xiao, Bing Qian, Xiaosen

    2015-02-13

    A large proportion of the NSCLC patients were insensitive to radiotherapy, but the exact mechanism is still unclear. This study explored the role of miR-25 in regulating sensitivity of NSCLC cells to ionizing radiation (IR) and its downstream targets. Based on measurement in tumor samples from NSCLC patients, this study found that miR-25 expression is upregulated in both NSCLC and radio-resistant NSCLC patients compared the healthy and radio-sensitive controls. In addition, BTG expression was found negatively correlated with miR-25a expression in the both tissues and cells. By applying luciferase reporter assay, we verified two putative binding sites between miR-25 and BTG2. Therefore, BTG2 is a directly target of miR-25 in NSCLC cancer. By applying loss-and-gain function analysis in NSCLC cell lines, we demonstrated that miR-25-BTG2 axis could directly regulated BTG2 expression and affect radiotherapy sensitivity of NSCLC cells. - Highlights: • miR-25 is upregulated, while BTG2 is downregulated in radioresistant NSCLC patients. • miR-25 modulates sensitivity to radiation induced apoptosis. • miR-25 directly targets BTG2 and suppresses its expression. • miR-25 modulates sensitivity to radiotherapy through inhibiting BTG2 expression.

  14. The sensitivity and specificity of control surface injuries in aircraft accident fatalities.

    PubMed

    Campman, Steven C; Luzi, Scott A

    2007-06-01

    Among the important determinations that aircraft crash investigators try to make is which occupant of an aircraft was attempting to control the aircraft at the time of the crash. The presence or absence of certain injuries of the extremities is used to help make this determination. These "control surface injuries" reportedly occur when crash forces are applied to a pilot's hands and feet through the aircraft's controls. We sought to clarify the significance of these injuries and the frequency with which their presence indicates that the decedent was the person that might have been trying to control the aircraft, questions that are frequently asked of the examining pathologist. We studied sequential fatalities of airplane and helicopter crashes in which autopsies were performed by the Office of the Armed Forces Medical Examiner, excluding those that were known to have been incapacitated before the crash and those that were known to have attempted to escape from the aircraft, collecting 100 "qualified" crash decedents. The incidence of control surface injuries was determined for both pilots and passengers. The sensitivity and specificity of control surface injuries were calculated by classifying the decedents into a 4-cell diagnostic matrix. The positive and negative predictive values for control surface injuries were also calculated. Injuries that met the published definitions of control surface injuries had high incidences in passengers, as well as pilots, giving the term control surface injury a diagnostically unacceptable sensitivity and specificity for indicating "a pilot attempting to control an aircraft." We offer caveats and refinements to the definition of these injuries that help to increase the sensitivity and specificity of this term. PMID:17525559

  15. Suppression of BRCA1 sensitizes cells to proteasome inhibitors

    PubMed Central

    Gu, Y; Bouwman, P; Greco, D; Saarela, J; Yadav, B; Jonkers, J; Kuznetsov, S G

    2014-01-01

    BRCA1 is a multifunctional protein best known for its role in DNA repair and association with breast and ovarian cancers. To uncover novel biologically significant molecular functions of BRCA1, we tested a panel of 198 approved and experimental drugs to inhibit growth of MDA-MB-231 breast cancer cells depleted for BRCA1 by siRNA. 26S proteasome inhibitors bortezomib and carfilzomib emerged as a new class of selective BRCA1-targeting agents. The effect was confirmed in HeLa and U2OS cancer cell lines using two independent siRNAs, and in mouse embryonic stem (ES) cells with inducible deletion of Brca1. Bortezomib treatment did not cause any increase in nuclear foci containing phosphorylated histone H2AX, and knockdown of BRCA2 did not entail sensitivity to bortezomib, suggesting that the DNA repair function of BRCA1 may not be directly involved. We found that a toxic effect of bortezomib on BRCA1-depleted cells is mostly due to deregulated cell cycle checkpoints mediated by RB1-E2F pathway and 53BP1. Similar to BRCA1, depletion of RB1 also conferred sensitivity to bortezomib, whereas suppression of E2F1 or 53BP1 together with BRCA1 reduced induction of apoptosis after bortezomib treatment. A gene expression microarray study identified additional genes activated by bortezomib treatment only in the context of inactivation of BRCA1 including a critical involvement of the ERN1-mediated unfolded protein response. Our data indicate that BRCA1 has a novel molecular function affecting cell cycle checkpoints in a manner dependent on the 26S proteasome activity. PMID:25522274

  16. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-08-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple.

  17. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    PubMed Central

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-01-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple. PMID:27489138

  18. Effects of delayed gastric emptying on postprandial glucose kinetics, insulin sensitivity, and β-cell function.

    PubMed

    Hinshaw, Ling; Schiavon, Michele; Mallad, Ashwini; Man, Chiara Dalla; Basu, Rita; Bharucha, Adil E; Cobelli, Claudio; Carter, Rickey E; Basu, Ananda; Kudva, Yogish C

    2014-09-15

    Controlling meal-related glucose excursions continues to be a therapeutic challenge in diabetes mellitus. Mechanistic reasons for this need to be understood better to develop appropriate therapies. To investigate delayed gastric emptying effects on postprandial glucose turnover, insulin sensitivity, and β-cell responsivity and function, as a feasibility study prior to studying patients with type 1 diabetes, we used the triple tracer technique C-peptide and oral minimal model approach in healthy subjects. A single dose of 30 μg of pramlintide administered at the start of a mixed meal was used to delay gastric emptying rates. With delayed gastric emptying rates, peak rate of meal glucose appearance was delayed, and rate of endogenous glucose production (EGP) was lower. C-peptide and oral minimal models enabled the assessments of β-cell function, insulin sensitivity, and β-cell responsivity simultaneously. Delayed gastric emptying induced by pramlintide improved total insulin sensitivity and decreased total β-cell responsivity. However, β-cell function as measured by total disposition index did not change. The improved whole body insulin sensitivity coupled with lower rate of appearance of EGP with delayed gastric emptying provides experimental proof of the importance of evaluating pramlintide in artificial endocrine pancreas approaches to reduce postprandial blood glucose variability in patients with type 1 diabetes. PMID:25074985

  19. Central Administration of Galanin Receptor 1 Agonist Boosted Insulin Sensitivity in Adipose Cells of Diabetic Rats

    PubMed Central

    Zhang, Zhenwen; Fang, Penghua; He, Biao; Guo, Lili; Runesson, Johan; Langel, Ülo; Shi, Mingyi; Zhu, Yan; Bo, Ping

    2016-01-01

    Our previous studies testified the beneficial effect of central galanin on insulin sensitivity of type 2 diabetic rats. The aim of the study was further to investigate whether central M617, a galanin receptor 1 agonist, can benefit insulin sensitivity. The effects of intracerebroventricular administration of M617 on insulin sensitivity and insulin signaling were evaluated in adipose tissues of type 2 diabetic rats. The results showed that central injection of M617 significantly increased plasma adiponectin contents, glucose infusion rates in hyperinsulinemic-euglycemic clamp tests, GLUT4 mRNA expression levels, GLUT4 contents in plasma membranes, and total cell membranes of the adipose cells but reduced the plasma C-reactive protein concentration in nondiabetic and diabetic rats. The ratios of GLUT4 contents were higher in plasma membranes to total cell membranes in both nondiabetic and diabetic M617 groups than each control. In addition, the central administration of M617 enhanced the ratios of pAkt/Akt and pAS160/AS160, but not phosphorylative cAMP response element-binding protein (pCREB)/CREB in the adipose cells of nondiabetic and diabetic rats. These results suggest that excitation of central galanin receptor 1 facilitates insulin sensitivity via activation of the Akt/AS160 signaling pathway in the fat cells of type 2 diabetic rats. PMID:27127795

  20. Pulmonary dendritic cell distribution and prevalence in guinea pig airways: effect of ovalbumin sensitization and challenge.

    PubMed

    Lawrence, T E; Millecchia, L L; Frazer, D G; Fedan, J S

    1997-08-01

    We characterized the localization and prevalence of dendritic cells (DC) in guinea pig airways before and after s.c. sensitization and aerosol challenge with ovalbumin (OVA). DC, eosinophils, macrophages, T cells and B cells in lung and trachea were identified and quantified in frozen sections using monoclonal antibodies and computer-assisted image analysis. Airway reactivity of conscious animals to inhaled methacholine was examined. In unsensitized animals, DC were localized primarily within the lamina propria of the trachea and bronchi, in the submucosa of the trachea and in the adventitia of the bronchi. In contrast to reported studies on rats, few DC were noted in the epithelium. After OVA challenge, sensitized animals demonstrated an early obstructive response and a late-phase response that was well developed by 18 hr. Challenge with OVA increased DC prevalence in the lamina propria and submucosa of the trachea and in the lamina propria and adventitia of the bronchi. There was widespread eosinophilia throughout the airways, but no changes in B cells or T cells were evident. Macrophages were increased in the epithelium of both OVA-treated and saline-treated animals. At 18 hr after challenge, sensitized guinea pigs but not saline-treated controls were hyperreactive to inhaled methacholine. Except for macrophages, none of these effects were observed after saline treatment. Our findings indicate that inflammation in the airways of OVA-sensitized guinea pigs involves infiltration of DC, which is seen at the time animals are hyperreactive to inhaled methacholine. PMID:9262368

  1. Energy Antenna for Efficient Dye-Sensitized Solar Cells.

    PubMed

    Kwon, Dong Yuel; Chang, Dong Min; Kim, Young Sik

    2015-02-01

    In this study, we investigated the effect of the placement of acceptor in dual donor based dye sensitizers (TPA-PTZ-CN, PTZ-TPA-CN). Triphenylamine (TPA) and phenothiazine (PTZ) are well known as electron donors and cyanoacetic acid (CN) is a known electron acceptor. The absorption spectrum of the dyes showed different form because of the different energy levels of molecular orbital (MO) of each dye and intramolecular energy transfer (EnT). The absorption spectrum of PTZ-TPA-CN was broader than that of TPA-PTZ-CN and its molar extinction coefficient was also higher than TPA-PTZ-CN. Because of its enhanced panchromatic absorption spectra, PTZ-TPA-CN showed better photovoltaic properties than the other dyes did. This work presents that optimizing the placement of acceptor in dual donor based dye would give good photovoltaic properties for dye-sensitized solar cells (DSSC).

  2. Natural dye -sensitized mesoporous ZnO solar cell

    NASA Astrophysics Data System (ADS)

    Wu, Qishuang; Shen, Yue; Wu, Guizhi; Li, Linyu; Cao, Meng; Gu, Feng

    2011-02-01

    Natural dye-sensitized solar cells (N-DSSCs) were assembled using chlorophyll sensitized mesoporous ZnO (based on FTO) as the photoanode and platinum plate as the cathode. The natural dyes (chlorophyll) were extracted from spinach by simple procedure. The absorption spectrum and fluorescence spectrum of chlorophyll were studied. Mesoporous ZnO (m-ZnO) applied to the N-DSSCs was synthesized through hydrothermal method. The structures and morphologies were characterized by X-ray Diffraction (XRD) and diffuse reflection. The results indicated that the samples had an average pore size of 17 nm and the m-ZnO was hexagonal wurtzite structure. The performances of the N-DSSCs were investigated under AM 1.5G illumination. The Voc of the N-DSSCs was about 480mv, and the Isc was about 470μA. The performance of the N-DSSCs could be further improved by adjusting its structure.

  3. Natural dye -sensitized mesoporous ZnO solar cell

    NASA Astrophysics Data System (ADS)

    Wu, Qishuang; Shen, Yue; Wu, Guizhi; Li, Linyu; Cao, Meng; Gu, Feng

    2010-10-01

    Natural dye-sensitized solar cells (N-DSSCs) were assembled using chlorophyll sensitized mesoporous ZnO (based on FTO) as the photoanode and platinum plate as the cathode. The natural dyes (chlorophyll) were extracted from spinach by simple procedure. The absorption spectrum and fluorescence spectrum of chlorophyll were studied. Mesoporous ZnO (m-ZnO) applied to the N-DSSCs was synthesized through hydrothermal method. The structures and morphologies were characterized by X-ray Diffraction (XRD) and diffuse reflection. The results indicated that the samples had an average pore size of 17 nm and the m-ZnO was hexagonal wurtzite structure. The performances of the N-DSSCs were investigated under AM 1.5G illumination. The Voc of the N-DSSCs was about 480mv, and the Isc was about 470μA. The performance of the N-DSSCs could be further improved by adjusting its structure.

  4. Halogen Bonding Promotes Higher Dye-Sensitized Solar Cell Photovoltages.

    PubMed

    Simon, Sarah J C; Parlane, Fraser G L; Swords, Wesley B; Kellett, Cameron W; Du, Chuan; Lam, Brian; Dean, Rebecca K; Hu, Ke; Meyer, Gerald J; Berlinguette, Curtis P

    2016-08-24

    We report here an enhancement in photovoltage for dye-sensitized solar cells (DSSCs) where halogen-bonding interactions exist between a nucleophilic electrolyte species (I(-)) and a photo-oxidized dye immobilized on a TiO2 surface. The triarylamine-based dyes under investigation showed larger rate constants for dye regeneration (kreg) by the nucleophilic electrolyte species when heavier halogen substituents were positioned on the dye. The open-circuit voltages (VOC) tracked these kreg values. This analysis of a homologous series of dyes that differ only in the identity of two halogen substituents provides compelling evidence that the DSSC photovoltage is sensitive to kreg. This study also provides the first direct evidence that halogen-bonding interactions between the dye and the electrolyte can bolster DSSC performance.

  5. Stable environmentally sensitive cationic hydrogels for controlled delivery applications.

    PubMed

    Deo, Namita; Ruetsch, S; Ramaprasad, K R; Kamath, Y

    2010-01-01

    New thermosensitive, cationic hydrogels were synthesized by the dispersion copolymerization of N-isopropylacrylamide (NIPAM) and (3-acrylamidopropyl)trimethylammonium chloride (AAPTAC). In the polymerization protocol, an amide-based comonomer, (3-acrylamidopropyl)trimethylammonium chloride, was reacted as a new alternative monomer for introducing positive charges into the thermosensitive hydrogel. The hydrogels were synthesized without making any pH adjustment in the aqueous medium. These hydrogel particles exhibited colloidal stability in the pH range of 1.5 to 11.0, while similar cationic hydrogels were reported to be unstable at pHs higher than 6. The stronger cationic character of the selected comonomer provided higher colloidal stability to the poly(NIPAM-co-AAPTAC) hydrogels. Furthermore, these hydrogels displayed sensitivity towards temperature, pH, and salt concentration. Interestingly, the particle size of hydrogels was found to be decreased significantly with an increase in temperature and salt concentration. In addition, using pyrene fluorescence spectroscopy, it was established that the hydrophobicity/hydrophilicity of the hydrogel particles was largely controlled by both pH and temperature. The thermosensitive hydrogels reported in this paper may be suitable for delivering different actives for cosmetic and medical applications. Although direct application of these hydrogel particles in cosmetics has not been shown at this stage, the methodology of making them and controlling their absorption and release properties as a function of temperature and pH has been demonstrated. Furthermore, these hydrogels may also have applications in scavenging organic and inorganic toxics.

  6. Space Telescope Sensitivity and Controls for Exoplanet Imaging

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark

    2012-01-01

    Herein we address design considerations and outline requirements for space telescopes with capabilities for high contrast imaging of exoplanets. The approach taken is to identify the span of potentially detectable Earth-sized terrestrial planets in the habitable zone of the nearest stars within 30 parsecs and estimate their inner working angles, flux ratios, SNR, sensitivities, wavefront error requirements and sensing and control times parametrically versus aperture size. We consider 1, 2, 4, 8 and 16-meter diameter telescope apertures. The achievable science, range of telescope architectures, and the coronagraphic approach are all active areas of research and are all subject to change in a rapidly evolving field. Thus, presented is a snapshot of our current understanding with the goal of limiting the choices to those that appear currently technically feasible. We describe the top-level metrics of inner working angle, contrast and photometric throughput and explore how they are related to the range of target stars. A critical point is that for each telescope architecture and coronagraphic choice the telescope stability requirements have differing impacts on the design for open versus closed-loop sensing and control.

  7. Cultured stem cells are sensitive to gravity changes

    NASA Astrophysics Data System (ADS)

    Buravkova, L. B.; Romanov, Yu. A.; Konstantinova, N. A.; Buravkov, S. V.; Gershovich, Yu. G.; Grivennikov, I. A.

    2008-09-01

    Stem and precursor cells play an important role in development and regeneration. The state of these cells is regulated by biochemical substances, mechanical stimuli and cellular interactions. To estimate gravity effects we used two types of cultured stem cells: human mesenchymal stromal cells (hMSCs) from bone marrow and mice embryonic stem (mESC) line R1. Gravity changes were simulated by long-term (4-7 days) slow clinorotation and leaded to decreased hMSC proliferation, changes of cell morphology and modified F-actin cytoskeleton. We did not find the shifts in cell phenotype except for decreased expression of HLA 1 and CD105 but excretion of IL-6 into medium increased significantly. Remodeling of cytoskeleton started after first 4 h and was similar to preapoptotic changes. This data suggested the modification in cell adhesion and possible commitment of hMSC. It was observed that expression of alkaline phosphatase by MSC in osteogenic medium was more intensive in control. On the contrary, clinorotation did not change formation of mESC colonies and increased proliferation activity in LIF+-medium. However, the number of embryonic bodies after clinorotation was less than in static control. It is suggested that ESCs kept the viability and proliferative potential but decreased the differentiation ability after changes in gravity stimulation.

  8. Chloroquine sensitizes breast cancer cells to chemotherapy independent of autophagy.

    PubMed

    Maycotte, Paola; Aryal, Suraj; Cummings, Christopher T; Thorburn, Jacqueline; Morgan, Michael J; Thorburn, Andrew

    2012-02-01

    Chloroquine (CQ) is a 4-aminoquinoline drug used for the treatment of diverse diseases. It inhibits lysosomal acidification and therefore prevents autophagy by blocking autophagosome fusion and degradation. In cancer treatment, CQ is often used in combination with chemotherapeutic drugs and radiation because it has been shown to enhance the efficacy of tumor cell killing. Since CQ and its derivatives are the only inhibitors of autophagy that are available for use in the clinic, multiple ongoing clinical trials are currently using CQ or hydroxychloroquine (HCQ) for this purpose, either alone, or in combination with other anticancer drugs. Here we show that in the mouse breast cancer cell lines, 67NR and 4T1, autophagy is induced by the DNA damaging agent cisplatin or by drugs that selectively target autophagy regulation, the PtdIns3K inhibitor LY294002, and the mTOR inhibitor rapamycin. In combination with these drugs, CQ sensitized to these treatments, though this effect was more evident with LY294002 and rapamycin treatment. Surprisingly, however, in these experiments CQ sensitization occurred independent of autophagy inhibition, since sensitization was not mimicked by Atg12, Beclin 1 knockdown or bafilomycin treatment, and occurred even in the absence of Atg12. We therefore propose that although CQ might be helpful in combination with cancer therapeutic drugs, its sensitizing effects can occur independently of autophagy inhibition. Consequently, this possibility should be considered in the ongoing clinical trials where CQ or HCQ are used in the treatment of cancer, and caution is warranted when CQ treatment is used in cytotoxic assays in autophagy research. PMID:22252008

  9. Chloroquine sensitizes breast cancer cells to chemotherapy independent of autophagy

    PubMed Central

    Maycotte, Paola; Aryal, Suraj; Cummings, Christopher T; Thorburn, Jacqueline; Morgan, Michael J

    2012-01-01

    Chloroquine (CQ) is a 4-aminoquinoline drug used for the treatment of diverse diseases. It inhibits lysosomal acidification and therefore prevents autophagy by blocking autophagosome fusion and degradation. In cancer treatment, CQ is often used in combination with chemotherapeutic drugs and radiation because it has been shown to enhance the efficacy of tumor cell killing. Since CQ and its derivatives are the only inhibitors of autophagy that are available for use in the clinic, multiple ongoing clinical trials are currently using CQ or hydroxychloroquine (HCQ) for this purpose, either alone, or in combination with other anticancer drugs. Here we show that in the mouse breast cancer cell lines, 67NR and 4T1, autophagy is induced by the DNA damaging agent cisplatin or by drugs that selectively target autophagy regulation, the PtdIns3K inhibitor LY294002, and the mTOR inhibitor rapamycin. In combination with these drugs, CQ sensitized to these treatments, though this effect was more evident with LY294002 and rapamycin treatment. Surprisingly, however, in these experiments CQ sensitization occurred independent of autophagy inhibition, since sensitization was not mimicked by Atg12, Beclin 1 knockdown or bafilomycin treatment, and occurred even in the absence of Atg12. We therefore propose that although CQ might be helpful in combination with cancer therapeutic drugs, its sensitizing effects can occur independently of autophagy inhibition. Consequently, this possibility should be considered in the ongoing clinical trials where CQ or HCQ are used in the treatment of cancer, and caution is warranted when CQ treatment is used in cytotoxic assays in autophagy research. PMID:22252008

  10. Green grasses as light harvesters in dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shanmugam, Vinoth; Manoharan, Subbaiah; Sharafali, A.; Anandan, Sambandam; Murugan, Ramaswamy

    2015-01-01

    Chlorophylls, the major pigments presented in plants are responsible for the process of photosynthesis. The working principle of dye sensitized solar cell (DSSC) is analogous to natural photosynthesis in light-harvesting and charge separation. In a similar way, natural dyes extracted from three types of grasses viz. Hierochloe Odorata (HO), Torulinium Odoratum (TO) and Dactyloctenium Aegyptium (DA) were used as light harvesters in dye sensitized solar cells (DSSCs). The UV-Vis absorption spectroscopy, Fourier transform infrared (FT-IR), and liquid chromatography-mass spectrometry (LC-MS) were used to characterize the dyes. The electron transport mechanism and internal resistance of the DSSCs were investigated by the electrochemical impedance spectroscopy (EIS). The performance of the cells fabricated with the grass extract shows comparable efficiencies with the reported natural dyes. Among the three types of grasses, the DSSC fabricated with the dye extracted from Hierochloe Odorata (HO) exhibited the maximum efficiency. LC-MS investigations indicated that the dominant pigment present in HO dye was pheophytin a (Pheo a).

  11. Doping of TiO2 for sensitized solar cells.

    PubMed

    Roose, Bart; Pathak, Sandeep; Steiner, Ullrich

    2015-11-21

    This review gives a detailed summary and evaluation of the use of TiO2 doping to improve the performance of dye sensitized solar cells. Doping has a major effect on the band structure and trap states of TiO2, which in turn affect important properties such as the conduction band energy, charge transport, recombination and collection. The defect states of TiO2 are highly dependent on the synthesis method and thus the effect of doping may vary for different synthesis techniques, making it difficult to compare the suitability of different dopants. High-throughput methods may be employed to achieve a rough prediction on the suitability of dopants for a specific synthesis method. It was however found that nearly every employed dopant can be used to increase device performance, indicating that the improvement is not so much caused by the dopant itself, as by the defects it eliminates from TiO2. Furthermore, with the field shifting from dye sensitized solar cells to perovskite solar cells, the role doping can play to further advance this emerging field is also discussed.

  12. The renaissance of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hardin, Brian E.; Snaith, Henry J.; McGehee, Michael D.

    2012-03-01

    Several recent major advances in the design of dyes and electrolytes for dye-sensitized solar cells have led to record power-conversion efficiencies. Donor-pi-acceptor dyes absorb much more strongly than commonly employed ruthenium-based dyes, thereby allowing most of the visible spectrum to be absorbed in thinner films. Light-trapping strategies are also improving photon absorption in thin films. New cobalt-based redox couples are making it possible to obtain higher open-circuit voltages, leading to a new record power-conversion efficiency of 12.3%. Solid-state hole conductor materials also have the potential to increase open-circuit voltages and are making dye-sensitized solar cells more manufacturable. Engineering the interface between the titania and the hole transport material is being used to reduce recombination and thus attain higher photocurrents and open-circuit voltages. The combination of these strategies promises to provide much more efficient and stable solar cells, paving the way for large-scale commercialization.

  13. Quasi Solid Polymer Electrolytes for Dye Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Dissanayake, M. A. K. Lakshman

    2013-07-01

    Dye-sensitized solar cell (DSSC) has been considered as an alternative to the conventional silicon solar cell because of low cost, easy fabrication and relatively high conversion efficiency. A DSSC consists of a dye-sensitized nanoparticulated TiO2 electrode, an electrolyte containing redox couple and a Pt coated counter electrode. Such solar cells based on an I-/I3- redox couple in an organic solvent usually have conversion efficiencies reaching around 11%. However, a major drawback of these solution based solar cells, originally developed by Gratzel and coworkers is the lack of long-term stability due to liquid leakage, usage of volatile liquids such as acetonitrile, electrode corrosion, and photodecomposition of the dye in the solvent medium. Therefore considerable research efforts have been made in recent years to replace the liquid electrolytes with solid polymer or quasi-solid polymer (gel) electrolytes. Among these approaches, the use of gel polymer electrolytes appears to give rise to successful results in terms of conversion efficiency. Conventional poly (ethylene oxide)(PEO)-based solid polymer electrolytes exhibit poor ionic conductivities at room temperature, which is not sufficient for practical applications. Therefore, most of the recent studies have been directed to the preparation and characterization of gel polymer electrolytes which exhibit higher ionic conductivity at ambient temperature while maintain quai-solid structure. These gel polymer electrolytes prepared by incorporating a liquid electrolyte into a matrix polymer such as polyacrylonitrile(PAN), poly(vinylidene fluoride)(PVdF), poly (methyl methacrylate) (PMMA) and PEO have been employed in quasi-solid-state DSSCs to achieve power conversion efficiencies of more than 5%. Significant improvements have been achieved in recent years by modifications of the electrolytes by optimizing the ionic salt, introducing additives such as inorganic nanofillers, organic molecules and ionic liquids in

  14. Clinical perspectives for the use of new hypoxic cell sensitizers

    SciTech Connect

    Brown, J.M.

    1982-09-01

    Experience with high pressure oxygen in combination with radiotherapy has shown that, for some tumors at least, the presence of hypoxic cells is a limiting factor in the ability to cure these tumors even with conventional daily fractionation. This suggests that hypoxic cell radiosensitizers, of which misonidazole (MISO) is the prototype drug, may play a role in improving the cure-rate of some tumors when combined with daily fractionation. Even for those tumors for which no improvement is seen when combined with daily fractionation, it is likely that there will be an important role for these sensitizers by using them in combination with regimens of only a few dose fractions. Because of the limiting side effects of neuropathy, a less toxic radiosensitizer than MISO is required to gain the full clinical benefit of these drugs. A possible way of achieving this is to reduce the lipid solubility (lipophilicity) of the compounds while still retaining their electron-affinity. This reduces the concentration of drug in the neural tissues (brain, peripheral nerves) without affecting the tumor concentration. However, if the lipophilicity is too low, the drugs are unable to enter the hypoxic cells and hence lose their radiosensitivity efficiency. It would appear that a lipophilicity given by an octanol:water partition coefficient of approximately 0.04 is optimum (cf. MISO = 0.43) with the 2-nitroimidazole amide SR-2508 the best in this series. Tumor levels of this drug of at least 7-8 times those obtained with MISO should be attainable clinically for no increase in neurotoxicity. Another property of electron-affinic sensitizers shows clinical promise. This is their ability to preferentially sensitize tumors compared to normal tissues to the cytotoxic action of several chemotherapeutic agents.

  15. Hypsometric control on glacier mass balance sensitivity in Alaska

    NASA Astrophysics Data System (ADS)

    McGrath, D.; Sass, L.; Arendt, A. A.; O'Neel, S.; Kienholz, C.; Larsen, C.; Burgess, E. W.

    2015-12-01

    Mass loss from glaciers in Alaska is dominated by strongly negative surface balances, particularly on small, continental glaciers but can be highly variable from glacier to glacier. Glacier hypsometry can exert significant control on mass balance sensitivity, particularly if the equilibrium line altitude (ELA) is in a broad area of low surface slope. In this study, we explore the spatial variability in glacier response to future climate forcings on the basis of hypsometry. We first derive mass balance sensitivities (30-70 m ELA / 1° C and 40-90 m ELA / 50% decrease in snow accumulation) from the ~50-year USGS Benchmark glaciers mass balance record. We subsequently assess mean climate fields in 2090-2100 derived from the IPCC AR5/CMIP5 RCP 6.0 5-model mean. Over glaciers in Alaska, we find 2-4° C warming and 10-20% increase in precipitation relative to 2006-2015, but a corresponding 0-50% decrease in snow accumulation due to rising temperatures. We assess changes in accumulation area ratios (AAR) to a rising ELA using binned individual glacier hypsometries. For an ELA increase of 150 m, the mean statewide AAR drops by 0.45, representing a 70% reduction in accumulation area on an individual glacier basis. Small, interior glaciers are the primary drivers of this reduction and for nearly 25% of all glaciers, the new ELA exceeds the glacier's maximum elevation, portending eventual loss. The loss of small glaciers, particularly in the drier interior of Alaska will significantly modify streamflow properties (flashy hydrographs, earlier and reduced peak flows, increased interannual variability, warmer temperatures) with poorly understood downstream ecosystem and oceanographic impacts.

  16. Sensitivity of staurosporine-induced differentiated RGC-5 cells to homocysteine

    PubMed Central

    Ganapathy, Preethi S.; Dun, Ying; Ha, Yonju; Duplantier, Jennifer; Allen, John Bradley; Farooq, Amina; Bozard, B. Renee; Smith, Sylvia B.

    2011-01-01

    PURPOSE Homocysteine is implicated in ganglion cell death associated with glaucoma. To understand mechanisms of homocysteine-induced cell death, we analyzed the sensitivity of the RGC-5 cell line, differentiated using staurosporine, to physiologically-relevant levels of the excitotoxic amino acid homocysteine. METHODS RGC-5 cells were differentiated 24 h using 316 nM staurosporine and tested for expression of Thy 1.2 via immunodetection, RT-PCR and immunoblotting. The sensitivity of staurosporine-differentiated RGC-5 cells to physiological levels of homocysteine (50, 100, 250 µM) and to high levels of homocysteine (1 mM), glutamate (1 mM) and oxidative stress (25 µM:10 mU/ml xanthine:xanthine oxidase) was assessed by TUNEL assay and by immunodetection of cleaved caspase-3. The sensitivity of undifferentiated RGC-5 cells to high (1, 5, and 10 mM) homocysteine was also examined. RESULTS Undifferentiated RGC-5 cells express Thy 1.2 mRNA and protein. Staurosporine-differentiated RGC-5 cells extend neurite processes and express Thy 1.2 after 24 h differentiation; they express NF-L after 1 and 3 days differentiation. Treatment of staurosporine-differentiated RGC-5 cells with 50, 100 or 250µM homocysteine did not alter neurite processes nor induce cell death (detected by TUNEL and active caspase-3) to a level greater than that observed in non-homocysteine-treated, staurosporine-differentiated cells. The 1 mM dosage of homocysteine in staurosporine-differentiated RGC-5 cells also did not induce cell death above control levels, although 18 h treatment of non-differentiated RGC-5 cells with 5 mM homocysteine decreased survival by 50%. CONCLUSIONS RGC-5 cells differentiated for 24 h with 316 nM staurosporine project robust neurite processes and are positive for ganglion cell markers consistent with a more neuronal phenotype than non- staurosporine-differentiated RGC-5 cells. However, concentrations of homocysteine known to induce ganglion cell death in vivo and in primary

  17. Effects of cell area on the performance of dye sensitized solar cell

    SciTech Connect

    Khatani, Mehboob E-mail: noranimuti-mohamed@petronas.com.my E-mail: azclement@yahoo.com Mohamed, Norani Muti E-mail: noranimuti-mohamed@petronas.com.my E-mail: azclement@yahoo.com Hamid, Nor Hisham E-mail: noranimuti-mohamed@petronas.com.my E-mail: azclement@yahoo.com Sahmer, Ahmad Zahrin E-mail: noranimuti-mohamed@petronas.com.my E-mail: azclement@yahoo.com Samsudin, Adel E-mail: noranimuti-mohamed@petronas.com.my E-mail: azclement@yahoo.com

    2014-10-24

    Dye sensitized solar cells (DSCs) have significant advantage over the current silicon cells by having low manufacturing cost and potentially high conversion efficiency. Therefore, DSCs are expected to be used as the next generation solar cell device that covers wide range of new applications. In order to achieve highly efficient DSCs for practical application, study on the effect of increasing the cell’s area on the performance of dye sensitized solar need to be carried out. Three different DSC cell areas namely, 1, 12.96 and 93.5 cm{sup 2} respectively were fabricated and analyzed through solar simulator and electrochemical impedance spectroscopy (EIS). From the analysis of electrochemical impedance spectroscopy (EIS), it was observed that the cell’s electron lifetime was influenced significantly by the cell’s area. Although the collection efficiency of all cells recorded to be approximately 100% but higher recombination rate with increased cell area reduced the performance of the cell.

  18. Molecular scale characterization of the titania-dye-solvent interface in dye-sensitized solar cells.

    PubMed

    Marquet, Philip; Andersson, Gunther; Snedden, Alan; Kloo, Lars; Atkin, Rob

    2010-06-15

    Charge separation at the dye/titania interface in dye sensitized solar cells is strongly influenced by the thickness and homogeneity of the sensitizing dye layer, as this controls the potential drop across the interface, and the probability of an excited electron being transferred from the dye to the titania. In this study we use atomic force microscopy and the depth profiling method neutral impact collision ion scattering spectroscopy (NICISS) to investigate the thickness and homogeneity of N719 dye adsorbed to titania before and after rinsing with pure acetonitrile. Both experimental methods show that the dye layers are closed but inhomogeneous. Inhomogeneity is more pronounced for unrinsed samples. PMID:20297833

  19. Weavable dye sensitized solar cells exploiting carbon nanotube yarns

    NASA Astrophysics Data System (ADS)

    Velten, Josef; Kuanyshbekova, Zharkynay; Göktepe, Özer; Göktepe, Fatma; Zakhidov, Anvar

    2013-05-01

    Weavable Dye Sensitized Solar Cells (DSSC) made with flexible yarns of conductive multiwalled carbon nanotubes (MWNTs) were produced having a power conversion efficiency above 3%. This was achieved with a specific design and careful consideration of the yarn function in the DSSC. Fermat yarns of MWNTs individually coated with mesoporous TiO2 layer were twisted together and coated with more mesoporous TiO2 to create a 3 dimensional photo electrode to overcome electron diffusion length issues. Archimedian yarns of MWNTs coated with a thin layer of platinum worked as a counter electrode to complete the architecture used in this DSSC.

  20. Towards low temperature sintering methods for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Murali, Sukanya

    Access to economically viable renewable energy sources is essential for the development of a globally sustainable society. Solar energy has a large potential to satisfy the future need for renewable energy sources. Dye sensitized solar cells are a third generation of photovoltaic technologies with the potential for low cost environmentally safe energy production. Commercialization of this technology requires that dye sensitized solar cells with higher efficiencies can be fabricated on flexible substrates. The commonly used material for the anode in a Dye Sensitized Solar Cell consists of titanium dioxide nanoparticles covered with a layer of light sensitizing dye. For efficient electron transport throughout the nanoparticle network, good particle interconnections are necessary. For low temperature processing these interconnections can be achieved through a hydrothermal process. The focus of this research is to understand at a fundamental level this reaction-based sintering process. A titanium alkoxide precursor was mixed with commercial titania nanoparticles and coated on a transparent conductive oxide substrate. The product of the hydrolysis and condensation of the alkoxide served to connect the nanoparticles thus improving the electrical conduction of the titania electrode; this was confirmed by solar cell testing and electrochemical impedance spectroscopy. To further understand the formation of interconnections during reactive sintering, a model system based on inert silica particles was investigated. Titanium alkoxide precursor was mixed with commercial silica particles and reacted. Three different types of silica particles were used: each with a different morphology. The silica-titania multilayers/powders were characterized using SEM, XRD and BET. The efficiency of DSSCs is higher when larger non-porous silica particles are used and thin nanocrystalline titania is coated on this superstructure. This gave insight into the locations where the reactive liquid

  1. Development of a highly sensitive galvanic cell oxygen sensor.

    PubMed

    Ogino, H; Asakura, K

    1995-02-01

    A highly sensitive galvanic cell oxygen sensor was successfully developed for determining parts per billion of oxygen in high purity gases such as nitrogen, argon, etc. The response of this improved sensor was proportional in the range of oxygen concentrations from 10.0 ppm to the detection limit. The response speed in this study was improved to within 90 sec for a 90% response. The detection limit was tentatively found to be less than 0.4 ppb corresponding to S N = 2 .

  2. Decitabine nanoconjugate sensitizes human glioblastoma cells to temozolomide.

    PubMed

    Cui, Yi; Naz, Asia; Thompson, David H; Irudayaraj, Joseph

    2015-04-01

    In this study, we developed and characterized a delivery system for the epigenetic demethylating drug, decitabine, to sensitize temozolomide-resistant human glioblastoma multiforme (GBM) cells to alkylating chemotherapy. A poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) based nanoconjugate was fabricated to encapsulate decitabine and achieved a better therapeutic response in GBM cells than that with the free drug. After synthesis, the highly efficient uptake process and intracellular dynamics of this nanoconjugate were monitored by single-molecule fluorescence tools. Our experiments demonstrated that, under an acidic pH due to active glycolysis in cancer cells, the PLGA-PEG nanovector could release the conjugated decitabine at a faster rate, after which the hydrolyzed lactic acid and glycolic acid would further acidify the intracellular microenvironment, thus providing positive feedback to increase the effective drug concentration and realize growth inhibition. In temozolomide-resistant GBM cells, decitabine can potentiate the cytotoxic DNA alkylation by counteracting cytosine methylation and reactivating tumor suppressor genes, such as p53 and p21. Owing to the excellent internalization and endolysosomal escape enabled by the PLGA-PEG backbone, the encapsulated decitabine exhibited a better anti-GBM potential than that of free drug molecules. Hence, the synthesized nanoconjugate and temozolomide could act in synergy to deliver a more potent and long-term antiproliferative effect against malignant GBM cells.

  3. Decitabine Nano-conjugate Sensitizing Human Glioblastoma Cells to Temozolomide

    PubMed Central

    Cui, Yi; Naz, Asia; Thompson, David H.; Irudayaraj, Joseph

    2015-01-01

    In this study we developed and characterized a delivery system for the epigenetic demethylating drug, decitabine, to sensitize temozolomide-resistant human glioblastoma multiforme (GBM) cells to alkylating chemotherapy. A poly(lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) based nano-conjugate was fabricated to encapsulate decitabine and achieved a better therapeutic response in GBM cells. After synthesis, the highly efficient uptake process and intracellular dynamics of this nano-conjugate was monitored by single-molecule fluorescence tools. Our experiments demonstrated that, under an acidic pH due to active glycolysis in cancer cells, the PLGA-PEG nano-vector could release the conjugated decitabine at a faster rate, after which the hydrolyzed lactic acid and glycolic acid would further acidify the intracellular microenvironment, thus providing a “positive feedback” to increase the effective drug concentration and realize growth inhibition. In temozolomide-resistant GBM cells, decitabine can potentiate the cytotoxic DNA alkylation by counteracting cytosine methylation and reactivating tumor suppressor genes, such as p53 and p21. Owing to excellent internalization and endo-lysosomal escape enabled by the PLGA-PEG backbone, the encapsulated decitabine exhibited a better anti-GBM potential than free drug molecules. Hence, the synthesized nano-conjugate and temozolomide could act in synergy to deliver a more potent and long-term anti-proliferation effect against malignant GBM cells. PMID:25751281

  4. Progress in nanostructured photoanodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Xueyang; Fang, Jian; Liu, Yong; Lin, Tong

    2016-09-01

    Solar cells represent a principal energy technology to convert light into electricity. Commercial solar cells are at present predominately produced by single- or multi-crystalline silicon wafers. The main drawback to silicon-based solar cells, however, is high material and manufacturing costs. Dye-sensitized solar cells (DSSCs) have attracted much attention during recent years because of the low production cost and other advantages. The photoanode (working electrode) plays a key role in determining the performance of DSSCs. In particular, nanostructured photoanodes with a large surface area, high electron transfer efficiency, and low electron recombination facilitate to prepare DSSCs with high energy conversion efficiency. In this review article, we summarize recent progress in the development of novel photoanodes for DSSCs. Effect of semiconductor material (e.g. TiO2, ZnO, SnO2, N2O5, and nano carbon), preparation, morphology and structure (e.g. nanoparticles, nanorods, nanofibers, nanotubes, fiber/particle composites, and hierarchical structure) on photovoltaic performance of DSSCs is described. The possibility of replacing silicon-based solar cells with DSSCs is discussed.

  5. Microbeam PIXE analysis of platinum resistant and sensitive ovarian cancer cells

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Bailey, M. J.; Coley, H.; Kirkby, K. J.; Jeynes, C.

    2010-06-01

    Microbeam PIXE was used to analyse platinum in single ovarian cancer cells. Carboplatin sensitive and resistant cells were grown as a monolayer on polypropylene and treated with either carboplatin or cisplatin. Pt from the carboplatin could not be detected. The Pt from cisplatin in the cells could be detected, and significantly more Zn was found in the resistant cells compared to the sensitive cells. The sensitive cells probably accumulated more cisplatin than the resistant ones.

  6. Microbeam studies of the sensitivity of structures within living cells

    NASA Technical Reports Server (NTRS)

    Braby, L. A.

    1992-01-01

    Determining the biological effects of low doses of radiation with high linear energy transfer (LET) is complicated by the stochastic nature of charged-particle interactions. Populations of cells exposed to very low radiation doses contain a few cells which have been hit by a charged particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, a few cells receive two or more events. Because the effects of damage produced by separate events can interact in the cell, we have had to make assumptions about the nature of these interactions in order to interpret the results of the experiments. Many of those assumptions can be tested if we can be sure of the number of charged-particle events which occur in individual cells, and correlate this number with the biological effect. We have developed a special irradiation facility at Pacific Northwest Laboratory (PNL) to control the actual number of charged particle tracks that pass through cell nuclei. The beam from a 2 MeV tandem accelerator is collimated to approximately 5 microns. Cells, grown in special dishes with 1.5 microns thick plastic bottoms, are positioned so that the desired portion of the cell aligns with the collimator. A shutter in the beam line is opened and closed after the desired number of particle tracks has been counted. This approach can be used to investigate the effects of the interaction between irradiated and unirradiated cells in an organized system, as well as to study the effects of spatial and temporal distribution of radiation damage within single cells.(ABSTRACT TRUNCATED AT 250 WORDS).

  7. Integration of biological photonic crystals in dye-sensitized solar cells for enhanced photocurrent generation

    NASA Astrophysics Data System (ADS)

    Campbell, Jeremy; Rorrer, Greg

    2013-10-01

    Dye-sensitized solar cells (DSSCs) rely on a network of titanium dioxide nanoparticles for electron transport and must balance carrier generation and collection. Adding photonic structures may increase light capture without affecting carrier collection. Diatoms are single-celled algae that biologically fabricate silicon dioxide cell walls which resemble photonic crystal slabs. We present a simple fabrication strategy that allows for uniform and controlled placement of biosilica within DSSCs. Integration of biosilica reduces photoanode transmittance to less than 5% prior to dye sensitization at loading levels as low as 6 wt% biosilica. Increased biosilica loading (17 wt%) provides additional enhancements in photocurrent generation. Reflectance measurements suggest that the enhancement results from the combined effects of photonic resonance and Mie scattering. Overall efficiency of these devices is improved by 8% and 14%, respectively.

  8. Study on the Fabrication of Paint-Type Si Quantum Dot-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Son, Min-Kyu; Kim, Hee-Je; Wang, Yuting; Uchida, Giichiro; Kamataki, Kunihiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2013-10-01

    Quantum dots (QDs) have attracted much attention with their quantum characteristics in the research field of photochemical solar cells. Si QD was introduced as one of alternatives to conventional QD materials. However, their large particles could not penetrate inside TiO2 layer. Therefore, this work proposed the paint-type Si QD-sensitized solar cell. Its heat durability was suitable for the fabrication of paint-type solar cell. Si QDs were fabricated by multihollow discharge plasma chemical vapor deposition and characterized. The paste type, sintering temperature, and Si ratio were controlled and analyzed for better performance. Finally, its performance was enhanced by ZnS surface modification and the whole process was much simplified without sensitizing process.

  9. Device modeling of dye-sensitized solar cells.

    PubMed

    Bisquert, Juan; Marcus, Rudolph A

    2014-01-01

    We review the concepts and methods of modeling of the dye-sensitized solar cell, starting from fundamental electron transfer theory, and using phenomenological transport-conservation equations. The models revised here are aimed at describing the components of the current-voltage curve of the solar cell, based on small perturbation experimental methods, and to such an end, a range of phenomena occurring in the nanoparticulate electron transport materials, and at interfaces, are covered. Disorder plays a major role in the definition of kinetic parameters, and we introduce single particle as well as collective function definitions of diffusion coefficient and electron lifetime. Based on these fundamental considerations, applied tools of analysis of impedance spectroscopy are described, and we outline in detail the theory of recombination via surface states that is successful to describe the measured recombination resistance and lifetime. PMID:24085559

  10. Dna-Enhanced Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Pollum, Marvin; Crespo-Hernandez, Carlos E.

    2013-06-01

    Dye-sensitized solar cells (DSSCs) are a promising alternative to the current silicon solar cell technologies. DSSCs have a lower manufacturing cost, can be made to be flexible, semi-transparent, and in any variety of colors for aesthetic applications. Despite these advantageous properties, the stability and power conversion efficiency of DSSCs are still lacking. Recently, we have shown that the adsorption of DNA onto the semiconductor surface of a typical DSSC improves its overall performance. Structure-function analysis, in conjunction with steady-state and time-resolved spectroscopic studies, are currently being done to understand this phenomenon and to uncover the mechanism by which DNA boosts the overall performance of DSSCs. This new knowledge is expected to facilitate the rational design of DSSCs that exhibit higher power conversion efficiency than those currently available.

  11. Glucose-deprivation increases thyroid cancer cells sensitivity to metformin.

    PubMed

    Bikas, Athanasios; Jensen, Kirk; Patel, Aneeta; Costello, John; McDaniel, Dennis; Klubo-Gwiezdzinska, Joanna; Larin, Olexander; Hoperia, Victoria; Burman, Kenneth D; Boyle, Lisa; Wartofsky, Leonard; Vasko, Vasyl

    2015-12-01

    Metformin inhibits thyroid cancer cell growth. We sought to determine if variable glucose concentrations in medium alter the anti-cancer efficacy of metformin. Thyroid cancer cells (FTC133 and BCPAP) were cultured in high-glucose (20 mM) and low-glucose (5 mM) medium before treatment with metformin. Cell viability and apoptosis assays were performed. Expression of glycolytic genes was examined by real-time PCR, western blot, and immunostaining. Metformin inhibited cellular proliferation in high-glucose medium and induced cell death in low-glucose medium. In low-, but not in high-glucose medium, metformin induced endoplasmic reticulum stress, autophagy, and oncosis. At micromolar concentrations, metformin induced phosphorylation of AMP-activated protein kinase and blocked p-pS6 in low-glucose medium. Metformin increased the rate of glucose consumption from the medium and prompted medium acidification. Medium supplementation with glucose reversed metformin-inducible morphological changes. Treatment with an inhibitor of glycolysis (2-deoxy-d-glucose (2-DG)) increased thyroid cancer cell sensitivity to metformin. The combination of 2-DG with metformin led to cell death. Thyroid cancer cell lines were characterized by over-expression of glycolytic genes, and metformin decreased the protein level of pyruvate kinase muscle 2 (PKM2). PKM2 expression was detected in recurrent thyroid cancer tissue samples. In conclusion, we have demonstrated that the glucose concentration in the cellular milieu is a factor modulating metformin's anti-cancer activity. These data suggest that the combination of metformin with inhibitors of glycolysis could represent a new strategy for the treatment of thyroid cancer.

  12. A Hybrid Tandem Solar Cell Combining a Dye-Sensitized and a Polymer Solar Cell.

    PubMed

    Shao, Zhipeng; Chen, Shuanghong; Zhang, Xuhui; Zhu, Liangzheng; Ye, Jiajiu; Dai, Songyuan

    2016-06-01

    A hybrid tandem solar cell was assambled by connecting a dye sensitized solar cell and a polymer solar cell in series. A N719 sensitized TiO2 was used as photocathode in dye-sensitized subcell, and a MEH-PPV/PCBM composite was used as active layer in the polymer subcell. The polymer subcell fabricated on the counter electrode of the dye sensitized solar cell. A solution processed TiO(x) layer was used as electron collection layer of the polymer sub cell and the charge recombination layer. The effects of the TiO(x) interlayer and the spectral overlap between the two sub cells have been studied and optimized. The results shows that a proper thickness of the TiO(x) layer is needed for tandem solar cells. Thick TiO(x) will enhance the series resistance, but too thin TiO(x), layer will damage the hole blocking effect and its hydrophilic. The resulting optimized tandem solar cells exhibited a power conversion efficiency of 1.28% with a V(oc) of 0.95 V under simulated 100 mW cm(-2) AM 1.5 illumination. PMID:27427604

  13. 3-Bromopyruvate induces necrotic cell death in sensitive melanoma cell lines

    SciTech Connect

    Qin, J.-Z.; Xin, H.; Nickoloff, B.J.

    2010-05-28

    Clinicians successfully utilize high uptake of radiolabeled glucose via PET scanning to localize metastases in melanoma patients. To take advantage of this altered metabolome, 3-bromopyruvate (BrPA) was used to overcome the notorious resistance of melanoma to cell death. Using four melanoma cell lines, BrPA triggered caspase independent necrosis in two lines, whilst the other two lines were resistant to killing. Mechanistically, sensitive cells differed from resistant cells by; constitutively lower levels of glutathione, reduction of glutathione by BrPA only in sensitive cells; increased superoxide anion reactive oxygen species, loss of outer mitochondrial membrane permeability, and rapid ATP depletion. Sensitive cell killing was blocked by N-acetylcysteine or glutathione. When glutathione levels were reduced in resistant cell lines, they became sensitive to killing by BrPA. Taken together, these results identify a metabolic-based Achilles' heel in melanoma cells to be exploited by use of BrPA. Future pre-clinical and clinical trials are warranted to translate these results into improved patient care for individuals suffering from metastatic melanoma.

  14. A Hybrid Tandem Solar Cell Combining a Dye-Sensitized and a Polymer Solar Cell.

    PubMed

    Shao, Zhipeng; Chen, Shuanghong; Zhang, Xuhui; Zhu, Liangzheng; Ye, Jiajiu; Dai, Songyuan

    2016-06-01

    A hybrid tandem solar cell was assambled by connecting a dye sensitized solar cell and a polymer solar cell in series. A N719 sensitized TiO2 was used as photocathode in dye-sensitized subcell, and a MEH-PPV/PCBM composite was used as active layer in the polymer subcell. The polymer subcell fabricated on the counter electrode of the dye sensitized solar cell. A solution processed TiO(x) layer was used as electron collection layer of the polymer sub cell and the charge recombination layer. The effects of the TiO(x) interlayer and the spectral overlap between the two sub cells have been studied and optimized. The results shows that a proper thickness of the TiO(x) layer is needed for tandem solar cells. Thick TiO(x) will enhance the series resistance, but too thin TiO(x), layer will damage the hole blocking effect and its hydrophilic. The resulting optimized tandem solar cells exhibited a power conversion efficiency of 1.28% with a V(oc) of 0.95 V under simulated 100 mW cm(-2) AM 1.5 illumination.

  15. B-1 B cell IgM antibody initiates T cell elicitation of contact sensitivity.

    PubMed

    Askenase, P W; Tsuji, R F

    2000-01-01

    Although B-1 B cells have received considerable attention, their actual role in the normal functioning of the immune system is unclear. The hypothesized role of B-1 cell IgM in natural protective immunity is just being established. We have uncovered a separate and novel role for B-1 cell IgM in initiating the elicitation of acquired T cell-dependent contact sensitivity (CS), the prototype of in vivo T cell immunity, early after immunization (within 4 days). The recent recognition of a similarly unanticipated role of B cells in a variety of T cell responses, may indicate that B-1 cell IgM has a broader role in immunity than thought previously. We showed that 24 hr CS responses, and rises in local IFN-gamma levels at 24 hrs later after antigen (Ag) challenge the ears, were absent in pan B cell and antibody deficient mice. The mechanism of B cell involvement in CS-initiation is via local C5a generation early (1-2 hrs) after antigen (Ag) challenge of the ears, in 4 day contact sensitized mice. C5a activates local mast cells to release serotonin (5-HT) and TNF alpha to induce endothelial ICAM-1 and VCAM-1, leading to T cell recruitment. We hypothesized that C5a was generated via complement activation due to antibodies forming local AgAb complexes, and that B-1 cell IgM was involved because isotype switching of B-2 cells to produce C-activating IgG isotypes, could not occur as early as day 4. Indeed, B-1 cell deficient CBA/N-xid mice lacked C5a in 2 hr ear extracts, and had impaired CS ear swelling and elaboration of IFN-gamma at 24 hrs. Importantly, adoptive transfer of purified normal peritoneal B-1 cells, or just i.v. injection of Ag-specific IgM monoclonal antibodies in sensitized xid, restored deficient early C5a and late 24 hr ear swelling. These results suggest that early after Ag challenge, specific B-1 cell IgM, produced at distant sites by prior sensitization, forms AgAb complexes that trigger elaboration of C5a, to activate mast cell release of vasoactive TNF

  16. Adenovirus-Mediated FKHRL1/TM Sensitizes Melanoma Cells to Apoptosis Induced by Temozolomide

    PubMed Central

    Egger, Michael E.; McNally, Lacey R.; Nitz, Jonathan; McMasters, Kelly M.

    2014-01-01

    Abstract Melanoma exhibits variable resistance to the alkylating agent temozolomide (TMZ). We evaluated the potential of adenovirus expressing forkhead human transcription factor like 1 triple mutant (Ad-FKHRL1/TM) to sensitize melanoma cells to TMZ. Four melanoma cell lines were treated with Ad-FKHRL1/TM and TMZ, alone or in combination. Apoptosis was assessed by activation and inhibition of caspase pathway, nuclei fragmentation, and annexin V staining. The potential therapeutic efficacy of Ad-FKHRL1/TM with TMZ was also assessed in a mouse melanoma xenograft model. Combination therapy of Ad-FKHRL1/TM and TMZ resulted in greater cell killing (<20% cell viability) compared with single therapy and controls (p<0.05). Combination indices of Ad-FKHRL1/TM and TMZ therapy indicated significant (p<0.05) synergistic killing effect. Greater apoptosis induction was found in cells treated with Ad-FKHRL1/TM and TMZ than with Ad-FKHRL1/TM or TMZ-treated cells alone. Treatment with TMZ enhanced adenovirus transgene expression in a cell type-dependent manner. In an in vivo model, combination therapy of Ad-FKHRL1/TM with TMZ results in greater tumor growth reduction in comparison with single treatments. We suggest that Ad-FKHRL1/TM is a promising vector to sensitize melanoma cells to TMZ, and that a combination of both approaches would be effective in the clinical setting. PMID:25238278

  17. Decreased sensitivity of drug-resistant cells towards T cell cytotoxicity.

    PubMed

    Classen, C F; Fulda, S; Friesen, C; Debatin, K M

    1999-03-01

    Killing of target cells by cytotoxic T cells is mediated by induction of apoptosis requiring functional death pathways. Kill is mediated either by the CD95 or the perforin/granzyme pathway. We found that SH-EP neuroblastoma cells are preferentially killed via CD95, while in the T leukemia cell line CEM CD95 and perforin/granzyme are involved. In both types of cell lines, cells resistant to CD95- and drug-induced apoptosis are crossresistant to cytotoxic T cell kill. Resistant cells show decreased apoptosis and deficient activation of caspases indicated by decreased cleavage of the prototype caspase substrate PARP. Preincubation with the caspase inhibitor zVAD-fmk strongly decreased LAK cell kill in sensitive cells. Although parental CEM cells could be sensitized for LAK kill by preincubation with doxorubicin, resistance could not be reverted in doxorubicin or CD95 resistant CEM cells. These data demonstrate the crossresistance in induction of apoptosis by different cytotoxic regimens in tumor cells and may have implications for the immunotherapy of tumors in which apoptosis resistance was induced by previous chemotherapy.

  18. Dye-sensitized solar cells using natural dyes as sensitizers from Malaysia local fruit `Buah Mertajam'

    NASA Astrophysics Data System (ADS)

    Hambali, N. A. M. Ahmad; Roshidah, N.; Hashim, M. Norhafiz; Mohamad, I. S.; Saad, N. Hidayah; Norizan, M. N.

    2015-05-01

    We experimentally demonstrate the high conversion efficiency, low cost, green technology and easy to fabricate dye-sensitized solar cells (DSSCs) using natural anthocyanin dyes as sensitizers. The DSSCs was fabricated by using natural anthocyanin dyes which were extracted from different parts of the plants inclusive `Buah Mertajam', `Buah Keriang Dot', `Bunga Geti', Hibiscus, Red Spinach and Henna. The natural anthocyanin dyes that found in flower, leaves and fruits were extracted by the simple procedures. This anthocyanin dye is used to replace the expensive chemical synthetic dyes due to its ability to effectively attach into the surface of Titanium dioxide (TiO2). A natural anthocyanin dyes molecule adsorbs to each particle of the TiO2 and acts as the absorber of the visible light. A natural anthocyanin dye from Buah Mertajam shows the best performance with the conversion efficiency of 5.948% and fill factor of 0.708 followed by natural anthocyanin dyes from `Buah Keriang Dot', `Bunga Geti', Hibiscus, Red Spinach and Henna. Buah Mertajam or scientifically known as eriglossum rubiginosum is a local Malaysia fruit.

  19. Prolonged insulin treatment sensitizes apoptosis pathways in pancreatic β cells.

    PubMed

    Bucris, E; Beck, A; Boura-Halfon, S; Isaac, R; Vinik, Y; Rosenzweig, T; Sampson, S R; Zick, Y

    2016-09-01

    Insulin resistance results from impaired insulin signaling in target tissues that leads to increased levels of insulin required to control plasma glucose levels. The cycle of hyperglycemia and hyperinsulinemia eventually leads to pancreatic cell deterioration and death by a mechanism that is yet unclear. Insulin induces ROS formation in several cell types. Furthermore, death of pancreatic cells induced by oxidative stress could be potentiated by insulin. Here, we investigated the mechanism underlying this phenomenon. Experiments were done on pancreatic cell lines (Min-6, RINm, INS-1), isolated mouse and human islets, and on cell lines derived from nonpancreatic sources. Insulin (100nM) for 24h selectively increased the production of ROS in pancreatic cells and isolated pancreatic islets, but only slightly affected the expression of antioxidant enzymes. This was accompanied by a time- and dose-dependent decrease in cellular reducing power of pancreatic cells induced by insulin and altered expression of several ER stress response elements including a significant increase in Trb3 and a slight increase in iNos The effect on iNos did not increase NO levels. Insulin also potentiated the decrease in cellular reducing power induced by H2O2 but not cytokines. Insulin decreased the expression of MCL-1, an antiapoptotic protein of the BCL family, and induced a modest yet significant increase in caspase 3/7 activity. In accord with these findings, inhibition of caspase activity eliminated the ability of insulin to increase cell death. We conclude that prolonged elevated levels of insulin may prime apoptosis and cell death-inducing mechanisms as a result of oxidative stress in pancreatic cells. PMID:27411561

  20. Bumetanide-sensitive sodium-22 transport in vascular smooth muscle cell of the spontaneously hypertensive rat

    SciTech Connect

    Tokushige, A.; Kino, M.; Tamura, H.; Hopp, L.; Searle, B.M.; Aviv, A.

    1986-05-01

    The effect of bumetanide, a known probe of Na+, K+ cotransport, on /sup 22/Na+ uptake and washout was examined in serially passed cultured vascular smooth muscle cells of spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY), and Wistar rats. In Ca2+-deficient medium, the drug exerted the greatest effect on /sup 22/Na+ washout in vascular smooth muscle cells from SHR and the least effect on cells from WKY. The respective mean values for the apparent bumetanide-sensitive /sup 22/Na+ washout rate constants (Ke; X 10(-2)/min) were 7.2, 4.3, and 1.7 for cells from SHR, WKY, and Wistar rats. In both 1 mM Ca2+ and Ca2+-deficient medium, in the presence of 1 mM ouabain, vascular smooth muscle cells from SHR had the highest plateau phase of /sup 22/Na+ uptake among the three cell preparations. All cells exhibited higher /sup 22/Na+ uptake in Ca2+-deficient medium than in 1 mM Ca2+ medium. Under this condition, bumetanide caused an additional rise in steady state /sup 22/Na+ uptake that was most pronounced in cells from SHR (21.3% versus 16.6% for Wistar rats and 4.8% for WKY). This finding indicates that a quantitatively greater inhibition of washout than of the uptake component of the bumetanide-sensitive /sup 22/Na+ transport occurs in Ca2+-deficient medium. It is concluded that, in Ca2+-deficient medium, the bumetanide-sensitive /sup 22/Na+ washout is higher in vascular smooth muscle cells of SHR than in those of normotensive controls and that this phenomenon reflects a higher Na+ turnover in vascular smooth muscle cell in the hypertensive rat strain.

  1. Rapid and sensitive quantitation of heme in hemoglobinized cells.

    PubMed

    Marcero, Jason R; Piel Iii, Robert B; Burch, Joseph S; Dailey, Harry A

    2016-01-01

    Rapid and accurate heme quantitation in the research lab has become more desirable as the crucial role that intracellular hemoproteins play in metabolism continues to emerge. Here, the time-honored approaches of pyridine hemochromogen and fluorescence heme assays are compared with direct absorbance-based technologies using the CLARiTY spectrophotometer. All samples tested with these methods were rich in hemoglobin-associated heme, including buffered hemoglobin standards, whole blood from mice, and murine erythroleukemia (MEL) and K562 cells. While the pyridine hemochromogen assay demonstrated the greatest linear range of heme detection, all 3 methods demonstrated similar analytical sensitivities and normalized limits of quantitation of ∼1 µM. Surprisingly, the fluorescence assay was only shown to be distinct in its ability to quantitate extremely small samples. Using the CLARiTY system in combination with pyridine hemochromogen and cell count data, a common hemoglobin extinction coefficient for blood and differentiating MEL and K562 cells of 0.46 µM-1 cm-1 was derived. This value was applied to supplemental experiments designed to measure MEL cell hemoglobinization in response to the addition or removal of factors previously shown to affect heme biosynthesis (e.g., L-glutamine, iron). PMID:27528073

  2. Novel proteasome inhibitor ixazomib sensitizes neuroblastoma cells to doxorubicin treatment

    PubMed Central

    Li, Haoyu; Chen, Zhenghu; Hu, Ting; Wang, Long; Yu, Yang; Zhao, Yanling; Sun, Wenijing; Guan, Shan; Pang, Jonathan C.; Woodfield, Sarah E.; Liu, Qing; Yang, Jianhua

    2016-01-01

    Neuroblastoma (NB) is the most common extracranial malignant solid tumor seen in children and continues to lead to the death of many pediatric cancer patients. The poor outcome in high risk NB is largely attributed to the development of chemoresistant tumor cells. Doxorubicin (dox) has been widely employed as a potent anti-cancer agent in chemotherapeutic regimens; however, it also leads to chemoresistance in many cancer types including NB. Thus, developing novel small molecules that can overcome dox-induced chemoresistance is a promising strategy in cancer therapy. Here we show that the second generation proteasome inhibitor ixazomib (MLN9708) not only inhibits NB cell proliferation and induces apoptosis in vitro but also enhances dox-induced cytotoxicity in NB cells. Ixazomib inhibits dox-induced NF-κB activity and sensitizes NB cells to dox-induced apoptosis. More importantly, ixazomib demonstrated potent anti-tumor efficacy in vivo by enhancing dox-induced apoptosis in an orthotopic xenograft NB mouse model. Collectively, our study illustrates the anti-tumor efficacy of ixazomib in NB both alone and in combination with dox, suggesting that combination therapy including ixazomib with traditional therapeutic agents such as dox is a viable strategy that may achieve better outcomes for NB patients. PMID:27687684

  3. Infrasound sensitizes human glioblastoma cells to cisplatin-induced apoptosis.

    PubMed

    Rachlin, Kenneth; Moore, Dan H; Yount, Garret

    2013-11-01

    The development of nontoxic agents that can selectively enhance the cytotoxicity of chemotherapy is an important aim in oncology. This study evaluates the ability of infrasound exposure to sensitize glioblastoma cells to cisplatin-induced apoptosis. The infrasound was delivered using a device designed to replicate the unique infrasound emissions measured during external Qigong treatments. Human glioblastoma cell lines harboring wild-type p53 (U87) or mutant p53 (U251, SF210, and SF188) were treated in culture with cisplatin, infrasound emissions, or the combination of the 2 agents. Induction of apoptosis was quantified after 24 hours by flow cytometry following annexin V/propidium iodide staining. Infrasound emissions alone, delivered at moderate levels (~10 mPa) with dynamic frequency content (7-13 Hz), did not induce apoptosis, yet combining infrasound with cisplatin augmented the induction of apoptosis by cisplatin in all the 4 cell lines (P < .05). Increased cellular uptake of the fluorophore calcein associated with infrasound exposure was quantified by fluorescence microscopy as well as flow cytometry, demonstrating increased cell membrane permeability. The 4 cell lines differed in the degree to which infrasound exposure increased calcein uptake, and these differences were predictive of the extent to which infrasound enhanced cisplatin-induced apoptosis. When exposed to specific frequencies, membrane permeabilization also appeared to be differentially responsive for each cell line, suggesting the potential for selective targeting of tissue types using isolated infrasonic frequencies. Additionally, the pressure amplitudes used in this study were several orders of magnitude less than those used in similar studies involving ultrasound and shock waves. The results of this study provide support for using infrasound to enhance the chemotherapeutic effects of cisplatin in a clinical setting. PMID:23165942

  4. 11. ENGINE TEST CELL BUILDING INTERIOR. CONTROL ROOM FOR CELLS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. ENGINE TEST CELL BUILDING INTERIOR. CONTROL ROOM FOR CELLS 2 AND 4. LOOKING SOUTHEAST. - Fairchild Air Force Base, Engine Test Cell Building, Near intersection of Arnold Street & George Avenue, Spokane, Spokane County, WA

  5. Are peripheral blood cells from patients with Alzheimer disease more sensitive to apoptotic stimuli?

    PubMed

    Bergman, Michael; Salman, Hertzel; Beloosesky, Yichayaou; Djaldetti, Meir; Bessler, Hanna

    2002-01-01

    One of the reasons for the increased susceptibility to infections in patients with Alzheimer disease may be enhanced apoptotic death of their peripheral leukocytes. If this is the case, the enhanced apoptosis may be due to components in the patients' sera or to an increased sensitivity of the cells to apoptotic stimuli. To examine this possibility, the percentage of apoptotic cells in the peripheral blood mononuclear cells (PBMC) from 12 patients with Alzheimer disease was compared with that of 12 age-matched non-demented persons and 12 middle-aged healthy control subjects. In addition, the effect of sera from subjects in the three groups on the apoptosis, interleukin (IL)-1beta, IL-2, IL-6, IL-10, and tumor necrosis factor (TNF)alpha production by peripheral blood cells from healthy control subjects was examined. It was found that the percentage of apoptotic PBMC from patients with Alzheimer disease was higher than that from the remaining two groups. However, incubation of control cells with sera from patients with Alzheimer disease and non-demented elderly persons did not affect the number of apoptotic cells. Sera from patients with Alzheimer disease and non-demented elderly subjects caused an increase in IL-2 and a decrease in IL-10 production by PBMC from middle-aged control subjects but did not affect IL-1beta, IL-6, and TNFalpha secretion, indicating alterations of the immune system related to aging.

  6. Effect of Ganoderma on drug-sensitive and multidrug-resistant small-cell lung carcinoma cells.

    PubMed

    Sadava, David; Still, David W; Mudry, Ryan R; Kane, Susan E

    2009-05-18

    Multidrug resistance is a major problem in small-cell lung cancer (SCLC). Ganoderma lucidum is a widely used herb in traditional Chinese medicine. We tested the effects of Ganoderma on drug-sensitive (H69) and multi-drug resistant (VPA) human SCLC cells. Both cells showed equal cytotoxicity when incubated with extracts of mycelia of 9 species of Ganoderma, including G. lucidum. Cells treated with the IC(50) of cytotoxic Ganoderma and analyzed by flow cytometry-PI staining showed increases in S phase. When compared untreated controls or SCLC cells treated with extracts of non-cytotoxic Ganoderma species, cells treated with extracts of cytotoxic Ganoderma species responded with an induction of apoptosis similar to cells treated with the chemotherapeutic drugs etoposide and doxorubicin. This was shown by four criteria: increased DNA fragmentation within cells as measured by ELISA; increased TUNEL staining for DNA breaks; increased specific activities of caspases 3 and 9, but not caspase 8 by colorimetric assays, indicating the endogenous pathway; and similar patterns changes in the expressions of 9 genes involved in the cell cycle/apoptosis, as measured by RT-PCR and capillary electrophoresis. Pre-incubation of drug-resistant SCLC cells with cytotoxic Ganoderma reduced the IC(50) for etoposide (3.4-0.21 microM) and doxorubicin (0.19-0.04 microM). These results show that extracts of several species of Ganoderma are cytotoxic to both drug-sensitive and drug-resistant SCLC cells, are pro-apoptotic, induce gene expression patterns that are similar to SCLC cells treated with chemotherapeutic drugs, and can reverse resistance to chemotherapeutic drugs.

  7. Effect of simulated microgravity on oxidation-sensitive gene expression in PC12 cells

    NASA Astrophysics Data System (ADS)

    Kwon, Ohwon; Sartor, Maureen; Tomlinson, Craig R.; Millard, Ronald W.; Olah, Mark E.; Sankovic, John M.; Banerjee, Rupak K.

    2006-01-01

    Oxygen utilization by and oxygen dependence of cellular processes may be different in biological systems that are exposed to microgravity (micro-g). A baseline in which cellular changes in oxygen sensitive molecular processes occur during micro-g conditions would be important to pursue this question. The objective of this research is to analyze oxidation-sensitive gene expression in a model cell line [rat pheochromocytoma (PC12)] under simulated micro-g conditions. The PC12 cell line is well characterized in its response to oxygen, and is widely recognized as a sensitive model for studying the responses of oxygen-sensitive molecular and cellular processes. This study uses the rotating wall vessel bioreactor (RWV) designed at NASA to simulate micro-g. Gene expression in PC12 cells in response to micro-g was analyzed by DNA microarray technology. The microarray analysis of PC12 cells cultured for 4 days under simulated micro-g under standardized oxygen environment conditions revealed more than 100 genes whose expression levels were changed at least twofold (up-regulation of 65 genes and down-regulation of 39 genes) compared with those from cells in the unit gravity (unit-g) control. This study observed that genes involved in the oxidoreductase activity category were most significantly differentially expressed under micro-g conditions. Also, known oxidation-sensitive transcription factors such as hypoxia-inducible factor-2α, c-myc, and the peroxisome proliferator-activated receptor-γ were changed significantly. Our initial results from the gene expression microarray studies may provide a context in which to evaluate the effect of varying oxygen environments on the background of differential gene regulation of biological processes under variable gravity conditions.

  8. A quantitative proteomics-based signature of platinum sensitivity in ovarian cancer cell lines

    PubMed Central

    Fan, Gaofeng; Wrzeszczynski, Kazimierz O.; Fu, Cexiong; Pappin, Darryl J.; Lucito, Robert; Tonks, Nicholas K.; Su, Gang

    2014-01-01

    Although DNA encodes the molecular instructions that underlie control of cell function, it is the proteins that are primarily responsible for implementing those instructions. Therefore, quantitative analyses of the proteome would be expected to yield insights into important candidates for the detection and treatment of disease. We present an iTRAQ (Isobaric Tagging for Relative and Absolute Quantification)-based proteomic analysis of 10 ovarian cancer cell lines and 2 normal ovarian surface epithelial cell lines. We profiled the abundance of 2659 cellular proteins, of which 1273 were common to all 12 cell lines. Of the 1273, 75 proteins exhibited elevated expression, and 164 proteins had diminished expression in the cancerous cells compared to the normal cell lines. The iTRAQ expression profiles allowed us to segregate cell lines based upon sensitivity and resistance to carboplatin. Importantly, we observed no substantial correlation between protein abundance and RNA expression or epigenetic, DNA methylation data. Furthermore, we could not discriminate between sensitivity and resistance to carboplatin on the basis of RNA expression and DNA methylation data alone. This study illustrates the importance of proteomics-based discovery for defining the basis for the carboplatin response in ovarian cancer and highlights candidate proteins, particularly involved in cellular redox regulation, homologous recombination and DNA damage repair, that otherwise could not have been predicted from whole genome and expression data sources alone. PMID:25406946

  9. Toxic variability and radiation sensitization by Pt(II) analogs in Salmonella typhimurium cells

    SciTech Connect

    Richmond, R.C.; Khokhar, A.R.; Teicher, B.A.; Douple, E.B.

    1984-09-01

    A rationale is presented for the development of toxic, i.e., cytocidal, antitumor drugs as clinical hypoxic cell radiation sensitizers. Pt(II) complex-induced hypoxic cell radiation sensitization may occur from Pt(II) complex in free solution and Pt(II) bound to DNA. Although both the free solution and the bound compartments may operate, the free solution compartment is more likely amenable to experimental and clinical control in the case of systemically active Pt drugs. Assuming equivalent cell uptake of different Pt(II) complexes, the free solution compartment of Pt(II) sensitization can be increased by utilizing less toxic analogs of the antitumor drug cis-dichlorodiammineplatinum(II). One such less toxic Pt(II) sensitizer currently in clinical use is found to be cis-(1,1-cyclobutanedicarboxylato)diammineplatinum(II). A new finding of both clinical and mechanistic usefulness is described: irradiation of hypoxic solutions of four cis-Pt(II) complexes, but not two trans-Pt(II) complexes, creates products that cause toxicity in excees of the unirradiated solutions.

  10. A microscale neuron and Schwann cell coculture model for increasing detection sensitivity of botulinum neurotoxin type A.

    PubMed

    Hong, Won S; Young, Edmond W K; Tepp, William H; Johnson, Eric A; Beebe, David J

    2013-07-01

    Botulinum neurotoxin (BoNT) is a potent and specific biomolecule that is both implicated as a potential threat in bioterrorism and used in therapeutics. Highly sensitive and robust assays that measure BoNT activity are needed to manage outbreak or controlled distribution of BoNT. Current in vivo and in vitro assays have limitations, including high costs and variability for mouse bioassays, extensive preparations for primary and stem cell-derived neurons, and inherent low sensitivity for cell lines. Sensitivity of cell lines can be increased by direct differentiation and with their physiological relevance (compared with cell-free strategies) and robustness (compared with primary cell strategies); adopting cell lines is an attractive alternative to in vivo assays. Here, we present two distinct strategies that improved sensitivity of a cell line to BoNT serotype A (BoNT/A) without direct differentiation. We developed a cell-based BoNT assay using microscale culture and coculture of neuronal and Schwann cell lines, NG108-15 and S16, respectively, to improve both sensitivity and physiological relevance. Results showed that NG108-15 and S16 coculture decreased EC50 from 12.5 to 0.8ng/µl (p < 0.001) in macroscale and from 2.6 to 1.1ng/µl (p = 0.006) in microscale. In addition, NG108-15 monoculture at microscale decreased EC50 from 12.5 to 2.6ng/µl (p < 0.001) compared with macroscale. Finally, controlling the spatial arrangement of microscale coculture revealed that S16-derived soluble factors can increase sensitivity. Thus, our study demonstrates two distinct strategies for increasing the sensitivity of a cell line to BoNT using coculture and microscale culture, thereby advancing assay technology for BoNT detection. PMID:23564642

  11. The Interplay of Maternal Sensitivity and Gentle Control When Predicting Children's Subsequent Academic Functioning: Evidence of Mediation by Effortful Control

    ERIC Educational Resources Information Center

    Kopystynska, Olena; Spinrad, Tracy L.; Seay, Danielle M.; Eisenberg, Nancy

    2016-01-01

    The goal of this work was to examine the complex interrelation of mothers' early gentle control and sensitivity in predicting children's effortful control (EC) and academic functioning. Maternal gentle control, maternal sensitivity, and children's EC were measured when children were 18, 30, and 42 months of age (T1, T2, and T3, respectively), and…

  12. Efficiency Records in Mesoscopic Dye-Sensitized Solar Cells.

    PubMed

    Albero, Josep; Atienzar, Pedro; Corma, Avelino; Garcia, Hermenegildo

    2015-08-01

    The aim of the present review article is to show the progress achieved in the efficiency of dye-sensitized solar cells (DSSCs) by evolution in the structure and composition of the dye. After an initial brief description of DSSCs and the operating mechanism the major part of the present article is organized according to the type of dye, trying to show the logic in the variation of the dye structure in order to achieve strong binding on the surface of the layer of nanoparticulate TiO2 , efficient interfacial electron injection between the excited dye and the semiconductor, and minimization of the unwanted dark current processes. Besides metal complexes, including polypyridyls and nitrogenated macro rings, organic dyes and inorganic light harvesters such as quantum dots and perovskites have also been included in the review. The last section summarizes the current state of the art and provides an overview on future developments in the field. PMID:26183911

  13. Dye Sensitized Solar Cells for Economically Viable Photovoltaic Systems.

    PubMed

    Jung, Hyun Suk; Lee, Jung-Kun

    2013-05-16

    TiO2 nanoparticle-based dye sensitized solar cells (DSSCs) have attracted a significant level of scientific and technological interest for their potential as economically viable photovoltaic devices. While DSSCs have multiple benefits such as material abundance, a short energy payback period, constant power output, and compatibility with flexible applications, there are still several challenges that hold back large scale commercialization. Critical factors determining the future of DSSCs involve energy conversion efficiency, long-term stability, and production cost. Continuous advancement of their long-term stability suggests that state-of-the-art DSSCs will operate for over 20 years without a significant decrease in performance. Nevertheless, key questions remain in regards to energy conversion efficiency improvements and material cost reduction. In this Perspective, the present state of the field and the ongoing efforts to address the requirements of DSSCs are summarized with views on the future of DSSCs.

  14. Plasmonic nanoparticles enhanced dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Liu, Fang; Meng, Weisi; Huang, Yidong

    2013-12-01

    Here we present investigations on utilizing two kinds of plasmonic nanoparticles (NPs) to enhance the efficiency of dye sensitized solar cells (DSCs). The Au@PVP NPs is proposed and present the specialty of adhesiveness to dye molecules, which could help to localize additional dye molecules near the plasmonic NPs, hence increasing the optical absorption consequently the power conversion efficiency (PCE) of the DSCs by 30% from 3.3% to 4.3%. Meanwhile, an irregular Au-Ag alloy popcorn-shaped NPs (popcorn NPs) with plenty of fine structures is also proposed and realized to enhance the light absorption of DSC. A pronounced absorption enhancement in a broadband wavelength range is observed due to the excitation of localized surface plasmon at different wavelengths. The PCE is enhanced by 32% from 5.94% to 7.85%.

  15. Rapid Dye Regeneration Mechanism of Dye-Sensitized Solar Cells.

    PubMed

    Jeon, Jiwon; Park, Young Choon; Han, Sang Soo; Goddard, William A; Lee, Yoon Sup; Kim, Hyungjun

    2014-12-18

    During the light-harvesting process of dye-sensitized solar cells (DSSCs), the hole localized on the dye after the charge separation yields an oxidized dye, D(+). The fast regeneration of D(+) using the redox pair (typically the I(-)/I3(-) couple) is critical for the efficient DSSCs. However, the kinetic processes of dye regeneration remain uncertain, still promoting vigorous debates. Here, we use molecular dynamics simulations to determine that the inner-sphere electron-transfer pathway provides a rapid dye regeneration route of ∼4 ps, where penetration of I(-) next to D(+) enables an immediate electron transfer, forming a kinetic barrier. This explains the recently reported ultrafast dye regeneration rate of a few picoseconds determined experimentally. We expect that our MD based comprehensive understanding of the dye regeneration mechanism will provide a helpful guideline in designing TiO2-dye-electrolyte interfacial systems for better performing DSSCs. PMID:26273975

  16. Efficiency Records in Mesoscopic Dye-Sensitized Solar Cells.

    PubMed

    Albero, Josep; Atienzar, Pedro; Corma, Avelino; Garcia, Hermenegildo

    2015-08-01

    The aim of the present review article is to show the progress achieved in the efficiency of dye-sensitized solar cells (DSSCs) by evolution in the structure and composition of the dye. After an initial brief description of DSSCs and the operating mechanism the major part of the present article is organized according to the type of dye, trying to show the logic in the variation of the dye structure in order to achieve strong binding on the surface of the layer of nanoparticulate TiO2 , efficient interfacial electron injection between the excited dye and the semiconductor, and minimization of the unwanted dark current processes. Besides metal complexes, including polypyridyls and nitrogenated macro rings, organic dyes and inorganic light harvesters such as quantum dots and perovskites have also been included in the review. The last section summarizes the current state of the art and provides an overview on future developments in the field.

  17. Y-27632 Increases Sensitivity of PANC-1 Cells to Epigallocatechin Gallate (EGCG) in Regulating Cell Proliferation and Migration

    PubMed Central

    Liu, Xing; Bi, Yongyi

    2016-01-01

    Background The study aimed to investigate the inhibitory effect of (1R,4r)-4-((R)-1-aminoethyl)-N-(pyridin-4-yl) cyclohexanecarboxamide (Y-27632) and (−)-epigallocatechin-3-gallate (EGCG) on the proliferation and migration of PANC-1 cells. EGCG, found in green tea, has been previously shown to be one of the most abundant and powerful catechins in cancer prevention and treatment. Y-27632, a selective inhibitor of rho-associated protein kinase 1, is widely used in treating cardiovascular disease, inflammation, and cancer. Material/Methods PANC-1 cells, maintained in Dulbecco’s Modified Eagle’s Medium, were treated with dimethyl sulfoxide (control) as well as different concentrations (20, 40, 60, and 80 μg/mL) of EGCG for 48 h. In addition, PANC-1 cells were treated separately with 60 μg/mL EGCG, 20 μM Y-27632, and EGCG combined with Y-27632 (60 μg/mL EGCG + 20 μM Y-27632) for 48 h. The effect of EGCG and Y-27632 on the proliferation and migration of PANC-1 cells was evaluated using Cell Counting Kit-8 and transwell migration assays. The expression of peroxisome proliferator–activated receptor alpha (PPARα) and Caspase-3 mRNA was determined by Quantitative real-time polymerase chain reaction (RT-qPCR). Results EGCG (20–80 μg/mL) inhibited cell viability in a dose-dependent manner. Y-27632 enhanced the sensitivity of PANC-1 cells to EGCG (by increasing the expression of PPARα and Caspase-3 mRNA) and suppressed cell proliferation. PANC-1 cell migration was inhibited by treatment with a combination of EGCG and Y-27632. Conclusions Y-27632 increases the sensitivity of PANC-1 cells to EGCG in regulating cell proliferation and migration, which is likely to be related to the expression of PPARα mRNA and Caspase-3 mRNA. PMID:27694793

  18. Controlled, scalable embryonic stem cell differentiation culture.

    PubMed

    Dang, Stephen M; Gerecht-Nir, Sharon; Chen, Jinny; Itskovitz-Eldor, Joseph; Zandstra, Peter W

    2004-01-01

    Embryonic stem (ES) cells are of significant interest as a renewable source of therapeutically useful cells. ES cell aggregation is important for both human and mouse embryoid body (EB) formation and the subsequent generation of ES cell derivatives. Aggregation between EBs (agglomeration), however, inhibits cell growth and differentiation in stirred or high-cell-density static cultures. We demonstrate that the agglomeration of two EBs is initiated by E-cadherin-mediated cell attachment and followed by active cell migration. We report the development of a technology capable of controlling cell-cell interactions in scalable culture by the mass encapsulation of ES cells in size-specified agarose capsules. When placed in stirred-suspension bioreactors, encapsulated ES cells can be used to produce scalable quantities of hematopoietic progenitor cells in a controlled environment.

  19. IL12-mediated sensitizing of T-cell receptor-dependent and -independent tumor cell killing.

    PubMed

    Braun, Matthias; Ress, Marie L; Yoo, Young-Eun; Scholz, Claus J; Eyrich, Matthias; Schlegel, Paul G; Wölfl, Matthias

    2016-07-01

    Interleukin 12 (IL12) is a key inflammatory cytokine critically influencing Th1/Tc1-T-cell responses at the time of initial antigen encounter. Therefore, it may be exploited for cancer immunotherapy. Here, we investigated how IL12, and other inflammatory cytokines, shape effector functions of human T-cells. Using a defined culture system, we followed the gradual differentiation and function of antigen-specific CD8(+) T cells from their initial activation as naïve T cells through their expansion phase as early memory cells to full differentiation as clonally expanded effector T cells. The addition of IL12 8 days after the initial priming event initiated two mechanistically separate events: First, IL12 sensitized the T-cell receptor (TCR) for antigen-specific activation, leading to an approximately 10-fold increase in peptide sensitivity and, in consequence, enhanced tumor cell killing. Secondly, IL12 enabled TCR/HLA-independent activation and cytotoxicity: this "non-specific" effect was mediated by the NK cell receptor DNAM1 (CD226) and dependent on ligand expression of the target cells. This IL12 regulated, DNAM1-mediated killing is dependent on src-kinases as well as on PTPRC (CD45) activity. Thus, besides enhancing TCR-mediated activation, we here identified for the first time a second IL12 mediated mechanism leading to activation of a receptor-dependent killing pathway via DNAM1. PMID:27622043

  20. Comparison of Dye-Sensitized Rutile- and Anatase-Based TiO2 Solar Cells

    SciTech Connect

    Park, N. G.; van de Lagemaat, J.; Frank, A. J.

    2000-01-01

    The objective of this work is to develop and optimize the new dye-sensitized solar cell technology. In view of the infancy of rutile material development for solar cells, the PV response of the dye-sensitized rutile-based solar cell is remarkably close to that of the anatase-based cell.

  1. Oxygen sensitivity of mitochondrial function in rat arterial chemoreceptor cells.

    PubMed

    Buckler, Keith J; Turner, Philip J

    2013-07-15

    The mechanism of oxygen sensing in arterial chemoreceptors is unknown but has often been linked to mitochondrial function. A common criticism of this hypothesis is that mitochondrial function is insensitive to physiological levels of hypoxia. Here we investigate the effects of hypoxia (down to 0.5% O2) on mitochondrial function in neonatal rat type-1 cells. The oxygen sensitivity of mitochondrial [NADH] was assessed by monitoring autofluorescence and increased in hypoxia with a P50 of 15 mm Hg (1 mm Hg = 133.3 Pa) in normal Tyrode or 46 mm Hg in Ca(2+)-free Tyrode. Hypoxia also depolarised mitochondrial membrane potential (m, measured using rhodamine 123) with a P50 of 3.1, 3.3 and 2.8 mm Hg in normal Tyrode, Ca(2+)-free Tyrode and Tyrode containing the Ca(2+) channel antagonist Ni(2+), respectively. In the presence of oligomycin and low carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP; 75 nm) m is maintained by electron transport working against an artificial proton leak. Under these conditions hypoxia depolarised m/inhibited electron transport with a P50 of 5.4 mm Hg. The effects of hypoxia upon cytochrome oxidase activity were investigated using rotenone, myxothiazol, antimycin A, oligomycin, ascorbate and the electron donor tetramethyl-p-phenylenediamine. Under these conditions m is maintained by complex IV activity alone. Hypoxia inhibited cytochrome oxidase activity (depolarised m) with a P50 of 2.6 mm Hg. In contrast hypoxia had little or no effect upon NADH (P50 = 0.3 mm Hg), electron transport or cytochrome oxidase activity in sympathetic neurons. In summary, type-1 cell mitochondria display extraordinary oxygen sensitivity commensurate with a role in oxygen sensing. The reasons for this highly unusual behaviour are as yet unexplained.

  2. Propranolol sensitizes thyroid cancer cells to cytotoxic effect of vemurafenib.

    PubMed

    Wei, Wei-Jun; Shen, Chen-Tian; Song, Hong-Jun; Qiu, Zhong-Ling; Luo, Quan-Yong

    2016-09-01

    Treatment options for advanced metastatic or progressive thyroid cancers are limited. Although targeted therapy specifically inhibiting intracellular kinase signaling pathways has markedly changed the therapeutic landscape, side-effects and resistance of single agent targeted therapy often leads to termination of the treatment. The objective of the present study was to identify the antitumor property of the non-selective β-adrenergic receptor antagonist propranolol for thyroid cancers. Human thyroid cancer cell lines 8505C, K1, BCPAP and BHP27 were used in the present study. Broad β-blocker propranolol and β2-specific antagonist ICI118551, but not β1-specific antagonist atenolol, inhibited the growth of 8505C and K1 cells. Propranolol treatment inhibited growth and induced apoptosis of 8505C cells in vitro and in vivo, which are closely associated with decreased expressions of cyclin D1 and anti-apoptotic Bcl-2. Expression of hexokinase 2 (HK2) and glucose transporter 1 (GLUT1) also decreased following propranolol intervention. 18F-FDG PET/CT imaging of the 8505C xenografts validated shrinkage of the tumors in the propranolol-treated group when compared to the phosphate‑buffered saline treated group. Finally, we found that propranolol can amplify the cytotoxicity of vemurafenib and sensitize thyroid cancer cells to cytotoxic effect of vemurafenib. Our present results suggest that propranolol has potential activity against thyroid cancers and investigation of the combination with targeted molecular therapy for progressive thyroid cancers could be beneficial. PMID:27432558

  3. Simple and sensitive method for monitoring drug-induced cell injury in cultured cells

    SciTech Connect

    Shirhatti, V.; Krishna, G.

    1985-06-01

    A simple, sensitive method has been developed for evaluating cell injury noninvasively in monolayer cells in culture. The cell ATP pool was radiolabeled by incubating the cells with (/sup 14/C)adenine. The uptake and incorporation of (/sup 14/C)adenine was shown to proportional to the number of cells. As determined by HPLC, about 65-70% of the incorporated /sup 14/C label was in the ATP pool, 15-20% was in the ADP pool, and the rest was in the 5'-AMP pool. When prelabeled cells were exposed to toxic drugs (acetaminophen, calcium ionophore A-23187, or daunomycin) there was a marked decrease in cell ATP with a concomitant increase in leakage of labeled nucleotides, mainly 5'-AMP and 5'IMP. The authors have shown that leakage of /sup 14/C label into the medium from the prelabeled cells may be employed for quantitation of cell injury. This new measure of toxicity was shown to correlate very well with LDH leakage from the cells, which is a well accepted measure of cell injury. The leakage of 5'-(/sup 14/C)AMP also correlated very well with the reduction of cell ATP in cardiac myocytes. This method has been used for monitoring drug-induced toxicity in liver cells, cardiac myocytes, and LB cells.

  4. Organic sensitizers featuring a planar indeno[1,2-b]-thiophene for efficient dye-sensitized solar cells.

    PubMed

    Lim, Kimin; Ju, Myung Jong; Song, Juman; Choi, In Taek; Do, Kwangsuk; Choi, Hyeju; Song, Kihyung; Kim, Hwan Kyu; Ko, Jaejung

    2013-08-01

    An efficient organic sensitizer (JK-306) featuring a planar indeno[1,2-b]thiophene as the π-linker of a bridging unit for dye-sensitized solar cells (DSSCs) was synthesized. The sensitizer had a strong molar absorption coefficient and a red-shifted absorption band compared with JK-305, which resulted in a significant increase in the short-circuit photocurrent density. We incorporated a highly congested bulky amino group into the 2',4'-dihexyloxybiphenyl-4-yl moiety, an electron donor, to diminish the charge recombination and to prevent aggregation of the sensitizer. Under standard AM 1.5G solar conditions, JK-306-sensitized cells in the presence of co-adsorbents chenodeoxycholic acid (CDCA) and 4-[bis(9,9-dimethyl-9H-fluoren-2-yl)amino]benzoic acid (HC-A), which afforded an overall conversion efficiency of 8.37% and 8.52%, respectively. Upon changing the I(-) /I3 (-) electrolyte to the Co(II) /Co(III) redox couple, the cell gave rise to a significantly improved conversion efficiency of 10.02% with the multifunctional HC-A, which is one of the highest values reported for DSSCs with a cobalt-based electrolyte. Furthermore, the JK-306-based solar cell with a polymer gel electrolyte revealed a high conversion efficiency of 7.61%, which is one of the highest values for cells based on organic sensitizers.

  5. Novel Ruthenium Sensitizers with a Phenothiazine Conjugated Bipyridyl Ligand for High-Efficiency Dye-Sensitized Solar Cells.

    PubMed

    She, Zhijie; Cheng, Yangyang; Zhang, Luoqiang; Li, Xiaoyu; Wu, Di; Guo, Qiang; Lan, Jingbo; Wang, Ruilin; You, Jingsong

    2015-12-23

    Two efficient ruthenium sensitizers with a phenothiazine-modified bipyridine as an ancillary ligand, coded SCZ-1 and SCZ-2, have been developed as dyes in dye-sensitized solar cells (DSSCs). Both sensitizers exhibit low-energy metal-to-ligand charge transfer (MLCT) bands centered at 539 nm with high molar extinction coefficients of 1.77 × 10(4) M(-1) cm(-1) for SCZ-1 and 1.66 × 10(4) M(-1) cm(-1) for SCZ-2, which are significantly higher than the corresponding value for the reference N719 (1.27 × 10(4) M(-1) cm(-1)), indicating that the light-harvesting capacity of ruthenium sensitizers can be reinforced by introducing phenothiazine moieties into the bipyridine ligand. Under AM 1.5G irradiation (100 mW cm(-2)), SCZ-1 and SCZ-2 sensitized DSSC devices show impressive power conversion efficiencies (PCE) up to 10.4% by using of iodide-based electrolytes, which exceeds that of N719 (9.9%) under the same conditions. Both of the open circuit voltage (VOC) and fill factor (FF) of SCZ-sensitized solar cells approximate to those of N719-sensitized cell. The relatively higher efficiencies of the SCZ-sensitized cells than that of N719-sensitized cell come from their higher short-circuit photocurrent density (JSC), which may be mainly attributed to the high absorption coefficient. The absorption spectrum and device efficiency of SCZ-1 are both quite close to those of SCZ-2, suggesting that the difference in alkyl chains on the N atom of phenothiazine is not a decisive factor in affecting the photovoltaic performance of dyes. PMID:26624527

  6. Sickle cell disease in mice is associated with sensitization of sensory nerve fibers

    PubMed Central

    Kenyon, Nicholas; Wang, Li; Spornick, Nicholas; Khaibullina, Alfia; Almeida, Luis EF; Cheng, Yao; Wang, Jichuan; Guptill, Virginia; Finkel, Julia C

    2015-01-01

    The pain phenotype in sickle cell disease (SCD) patients is highly variable. A small percentage of SCD patients experience many vaso-occlusive crises/year, 5% of patients account for over 30% of pain episodes, while 39% report few episodes of severe pain. Clearly, a better understanding of the pathobiology of SCD is needed to improve its therapy. Humanized sickle cell mice recapitulate several phenotypes of SCD patients and provide a model for the study of SCD pain. Researchers have shown that one strain of humanized SCD mice, the BERK strain, has abnormal pain phenotype. However, the nociception phenotype of another humanized SCD mouse strain, the Townes strain, has not been described. In a large cross-sectional study of BERK and Townes SCD mice, we examined thermosensory response and sensory nerve fiber function using sine-wave electrical stimulation at 2000, 250, and 5 Hz to stimulate preferentially Aβ, Aδ, and C sensory nerve fibers, respectively. We found that BERK and Townes mice, compared to respective controls, had decreases in 2000, 250, and 5 Hz current vocalization thresholds in patterns that suggest sensitization of a broad spectrum of sensory nerve fibers. In addition, the pattern of sensitization of sensory fibers varied according to strain, sex, age, and mouse genotype. In a similarly variable pattern, Townes and BERKs also had significantly altered sensitivity to noxious thermal stimuli in agreement with what has been shown by others. In summary, the analysis of somatosensory function using sine-wave electrical stimulation in humanized sickle cell mice suggests that in SCD, both myelinated and unmyelinated, fibers are sensitized. The pattern of sensory fiber sensitization is distinct from that observed in pain models of neuropathic and inflammatory pain. These findings raise the possibility that sensitization of a broad spectrum of sensory fibers might contribute to the altered and variable nociception phenotype in SCD. PMID:25070860

  7. Blood Pressure and Amiloride-Sensitive Sodium Channels in Vascular and Renal Cells

    PubMed Central

    Warnock, David G.; Kusche-Vihrog, Kristina; Tarjus, Antoine; Sheng, Shaohu; Oberleithner, Hans; Kleyman, Thomas R.; Jaisser, Frederic

    2014-01-01

    This review is focused on the expression and regulation of amiloride-sensitive sodium channels in the epithelial cells of the aldosterone-sensitive distal nephron (ENaC) and amiloride-sensitive sodium channel activity in vascular endothelial and smooth muscle cells. Guyton’s hypothesis stated that blood pressure control is critically dependent on vascular tone and fluid handling by the kidney. With the study of Mendelian forms of hypertension and their corresponding transgenic mouse models, the main components of the aldosterone- and angiotensin-dependent sodium transporters have been identified over the past 20 years. Proteolytic processing of the ENaC external domain, and inhibition by increased sodium concentrations are important features of the ENaC complexes expressed in the distal nephron. In contrast, amiloride-sensitive sodium channels expressed in the vascular system are activated by increased external sodium concentrations, resulting in changes in the mechanical properties and function of endothelial cells. Mechano-sensitivity and shear stress affect both epithelial and vascular sodium channel activity. The synergistic effects and complementary regulation of the epithelial and vascular systems are consistent with the Guytonian model of volume and blood pressure regulation, and may reflect sequential evolution of the two systems. The integration of vascular tone, renal perfusion and regulation of renal sodium reabsorption is the central underpinning of the Guytonian model. We summarize the recent evidence in this review that describes the central role of amiloride-sensitive sodium channels in the efferent (e.g., vascular) and afferent (e.g., epithelial) arms of this homeostatic system. PMID:24419567

  8. TAT-RasGAP317-326 requires p53 and PUMA to sensitize tumor cells to genotoxins.

    PubMed

    Michod, David; Widmann, Christian

    2007-05-01

    Although chemotherapy has revolutionized cancer treatment, the associated side effects induced by lack of specificity to tumor cells remain a challenging problem. We have previously shown that TAT-RasGAP(317-326),a cell-permeable peptide derived from RasGAP, specifically sensitizes cancer cells to the action of genotoxins. The underlying mechanisms of this sensitization were not defined however. Here, we report that TAT-RasGAP(317-326) requires p53, but not the Ras effectors Akt and extracellular signal-regulated kinase, to mediate its tumor sensitization abilities. The TAT-RasGAP(317-326) peptide, although not modulating the transcriptional activity of p53 or its phosphorylation and acetylation status, nevertheless requires a functional p53 cellular status to increase the sensitivity of tumor cells to genotoxins. Genes regulated by p53 encode proapoptotic proteins, such as PUMA, and cell cycle control proteins, such as p21. The ability of TAT-RasGAP(317-326) to sensitize cancer cells was found to require PUMA but not p21. TAT-RasGAP(317-326) did not affect PUMA levels, however, but increased genotoxin-induced mitochondrial depolarization and caspase-3 activation. These results indicate that TAT-RasGAP(317-326) sensitizes tumor cells by activating signals that intersect with the p53 pathway downstream of, or at the level of, proapoptotic p53 target gene products to increase the activation of the mitochondrial death pathway.

  9. Functional inactivation of Rb sensitizes cancer cells to TSC2 inactivation induced cell Death

    PubMed Central

    Danos, Arpad M.; Liao, Yang; Li, Xuan; Du, Wei

    2012-01-01

    We showed previously that inactivation of TSC2 induces death in cancer cells lacking the Retinoblastoma (Rb) tumor suppressor under stress conditions, suggesting that inactivation of TSC2 can potentially be used as an approach to specifically kill cancers that have lost WT Rb. As Rb is often inactivated in cancers by overexpression of cyclin D1, loss of p16ink4a cdk inhibitor, or expression of viral oncoproteins, it will be interesting to determine if such functional inactivation of Rb would similarly sensitize cancer cells to TSC2 inactivation induced cell death. In addition, many cancers lack functional Pten, resulting in increased PI3K/Akt signaling that has been shown to modulate E2F-induced cell death. Therefore it will be interesting to test whether loss of Pten will affect TSC2 inactivation induced killing of Rb mutant cancer cells. Here, we show that overexpression of Cyclin D1 or the viral oncogene E1a sensitizes cancer cells to TSC2 knockdown induced cell death and growth inhibition. On the other hand, knockdown of p16ink4a sensitizes cancer cells to TSC2 knockdown induced cell death in a manner that is likely dependant on serum induction of Cyclin D1 to inactivate the Rb function. Additionally, we demonstrate that loss of Pten does not interfere with TSC2 knockdown induced cell death in Rb mutant cancer cells. Together, these results suggest that TSC2 is potentially a useful target for a large spectrum of cancer types with an inactivated Rb pathway. PMID:23022476

  10. Immature rat Leydig cells are intrinsically less sensitive than adult Leydig cells to ethane dimethanesulfonate.

    PubMed

    Kelce, W R; Zirkin, B R; Ewing, L L

    1991-11-01

    Leydig cells from immature rat testes appear to be insensitive to doses of ethane-1,2-dimethanesulfonate (EDS) which eliminate Leydig cells from adult rat testes. We sought to determine whether this differential response to EDS is intrinsic to the Leydig cell or mediated by other intra- or extratesticular differences between adult and immature rats. To differentiate among these possibilities, Leydig cells were exposed to EDS (1) in vivo, (2) through in vitro testicular perfusion, or (3) in highly purified Leydig cell primary cultures. Four days after ip injections of 85 mg EDS/kg body wt Leydig cells were eliminated from testes of adult, but not immature rats. Total androgen production by testes perfused in vitro with 94 micrograms EDS/ml was dramatically reduced in adult, but not immature rats. Highly purified adult, but not immature, rat Leydig cells were far more sensitive to the effects of EDS on luteinizing hormone-stimulated androgen production (functional effects; apparent EC50 = 94 for adult and 407 micrograms/ml for immature rat Leydig cells) and on [35S]methionine incorporation (cytotoxic effects; apparent EC50 = 140 for adult and 1000 micrograms/ml for immature rat Leydig cells). Finally, the in vitro effects of EDS were both cell type and chemical specific. Since the differential response of adult and immature rat Leydig cells to EDS was manifest in vivo, during in vitro testicular perfusion, and in highly purified Leydig cell primary cultures, we conclude that immature rat Leydig cells are intrinsically less sensitive to the specific cytotoxic effects of EDS than adult rat Leydig cells.

  11. Role of ATP in the sensitivity to heat and the induction of apoptosis in mammalian cells.

    PubMed

    Miyazaki, N; Kurihara, K; Nakano, H; Shinohara, K

    2002-01-01

    Heat-induced cell death and apoptosis were studied with respect to intracellular ATP. Studies on the relationship between hyperthermic cell-killing at 44 degrees C and cellular ATP levels in four cell lines grown as monolayers and six cell lines grown in suspension showed good correlations between cellular ATP levels and the sensitivity to heat. D(0) values (the dose required to reduce survival in the linear portion of the response by 63%) linearly increased with an increase in cellular ATP levels. No such changes in sensitivity to heat were observed between the cells cultured at different cell densities, regardless of the change in the cellular ATP level. These results suggest that cellular intrinsic ability to supply ATP rather than the level of pooled ATP per se is responsible for the thermal response. Heat-induced apoptosis in L5178Y cells was observed following treatment at 42 degrees C for 70 min, 44 degrees C for 20 min or 47 degrees C for 3 min, which corresponded to surviving fractions of 25, 0.6 and 0.8%, respectively, but not at 47 degrees C for 20 min, indicating that mild heat shock induced apoptosis. 2-deoxyglucose (2DG) and 2,4-dinitrophenol (DNP) increased the sensitivity to heat and affected the mode of cell death. Cells treated with 2DG and DNP (2DG/DNP) were heated at 42 degrees C for 20 min, and then incubated at 37 degrees C for up to 2h in the presence or absence of 2DG/DNP. In the absence of 2DG/DNP, the cellular ATP level recovered to 76% of the control level and DNA ladder formation was observed, whereas in the presence of 2DG/DNP, the cellular ATP level was further decreased (3-7% of the control) and no DNA fragmentation was detected. These results suggest that the inhibition of ATP synthesis is closely associated with the enhancement of sensitivity to heat and that ATP is required for the induction of apoptosis.

  12. ATM-deficiency sensitizes Mantle Cell Lymphoma cells to PARP-1 inhibitors

    PubMed Central

    Williamson, Chris T.; Muzik, Huong; Turhan, Ali G.; Zamò, Alberto; O’Connor, Mark J.; Bebb, D. Gwyn; Lees-Miller, Susan P.

    2013-01-01

    Poly-ADP ribose polymerase-1 (PARP-1) inhibition is toxic to cells with mutations in the breast and ovarian cancer susceptibility genes BRCA1 or BRCA2, a concept, termed synthetic lethality. However, whether this approach is applicable to other human cancers with defects in other DNA repair genes has yet to be determined. The Ataxia-Telangiectasia Mutated (ATM) gene is altered in a number of human cancers including Mantle Cell Lymphoma (MCL). Here, we characterize a panel of MCL cell lines for ATM status and function and investigate the potential for synthetic lethality in MCL in the presence of small molecule inhibitors of PARP-1. We show that Granta-519 and UPN2 cells have low levels of ATM protein, are defective in DNA damage-induced ATM-dependent signaling, are radiation sensitive and have cell cycle checkpoint defects: all characteristics of defective ATM function. Significantly, Granta-519 and UPN2 cells were more sensitive to PARP-1 inhibition, than were the ATM-proficient MCL cell lines examined. Furthermore, the PARP-1 inhibitor olaparib (previously known as AZD2281/KU-0059436) significantly decreased tumour growth and increased overall survival in mice bearing subcutaneous xenografts of ATM-deficient Granta-519 cells, while producing only a modest effect on overall survival of mice bearing xenografts of the ATM-proficient cell line, Z138. Thus, PARP inhibitors have therapeutic potential in the treatment of MCL and the concept of synthetic lethality extends to human cancers with ATM alterations. PMID:20124459

  13. Resveratrol sensitizes glioblastoma-initiating cells to temozolomide by inducing cell apoptosis and promoting differentiation.

    PubMed

    Li, Hao; Liu, Yaodong; Jiao, Yumin; Guo, Anchen; Xu, Xiaoxue; Qu, Xianjun; Wang, Shuo; Zhao, Jizong; Li, Ye; Cao, Yong

    2016-01-01

    Glioblastoma-initiating cells play crucial roles in the origin, growth, and recurrence of glioblastoma multiforme. The elimination of glioblastoma-initiating cells is believed to be a key strategy for achieving long-term survival of glioblastoma patients due to the highly resistant property of glioblastoma-initiating cells to temozolomide. Resveratrol, a naturally occurring polyphenol, has been widely studied as a promising candidate for cancer prevention and treatment. Whether resveratrol could enhance the sensitivity of glioblastoma-initiating cells to temozolomide therapy has not yet been reported. Here, using patient-derived glioblastoma-initiating cell lines, we found that resveratrol sensitized glioblastoma-initiating cells to temozolomide both in vitro and in vivo. Furthermore, we showed that resveratrol enhanced glioblastoma-initiating cells to temozolomide-induced apoptosis through DNA double-stranded breaks/pATM/pATR/p53 pathway activation, and promoted glioblastoma-initiating cell differentiation involving p-STAT3 inactivation. Our results propose that temozolomide and resveratrol combination strategy may be effective in the management of glioblastoma patients, particularly for those patients who have been present with a high abundance of glioblastoma-initiating cells in their tumors and show slight responsiveness to temozolomide.

  14. Guadecitabine (SGI-110) priming sensitizes hepatocellular carcinoma cells to oxaliplatin.

    PubMed

    Kuang, Yuting; El-Khoueiry, Anthony; Taverna, Pietro; Ljungman, Mats; Neamati, Nouri

    2015-11-01

    Promoter DNA hypermethylation is an important biomarker of hepatocellular carcinoma (HCC), supporting the potential utility of demethylating agents in this disease. Guadecitabine (SGI-110) is a second-generation hypomethylating agent formulated as a dinucleotide of decitabine and deoxyguanosine that yields longer half-life and more extended decitabine exposure than decitabine IV infusion. Here we performed preclinical evaluation of SGI-110 in HCC models to guide the design of a phase I/II clinical trial. HCC cell lines and xenograft models were used to determine the antitumor activity of SGI-110 as a single agent and in combination with oxaliplatin. Pretreatment with low doses of SGI-110 significantly synergized with oxaliplatin yielding enhanced cytotoxicity. The combination of SGI-110 and oxaliplatin was well tolerated and significantly delayed tumor growth in mice compared to oxaliplatin alone. Bromouridine-labeled RNA sequencing (Bru-seq) was employed to elucidate the effects of SGI-110 and/or oxaliplatin on genome-wide transcription. SGI-110 and the combination treatment inhibited the expression of genes involved in WNT/EGF/IGF signaling. DNMT1 and survivin were identified as novel PD markers to monitor the efficacy of the combination treatment. In conclusion, SGI-110 priming sensitizes HCC cells to oxaliplatin by inhibiting distinct signaling pathways. We expect that this combination treatment will show low toxicity and high efficacy in patients. Our study supports the use of the combination of low doses of SGI-110 and oxaliplatin in HCC patients.

  15. Nature of photovoltaic action in dye-sensitized solar cells

    SciTech Connect

    Cahen, D.; Hodes, G.; Graetzel, M.; Guillemoles, J.F.; Riess, I.

    2000-03-09

    The authors explain the cause for the photocurrent and photovoltage in nanocrystalline, mesoporous dye-sensitized solar cells, in terms of the separation, recombination, and transport of electronic charge as well as in terms of electron energetics. On the basis of available experimental data, the basic cause for the photovoltage was confirmed as the change in the electron concentration in the nanocrystalline electron conductor that results from photoinduced charge injection from the dye. The maximum photovoltage is given by the difference in electron energies between the redox level and the bottom of the electron conductor's conduction band, rather than by any difference in electrical potential in the cell, in the dark. Charge separation occurs because of the energetic and entropic driving forces that exist at the dye/electron conductor interface, with charge transport aided by such driving forces at the electron conductor-contact interface. The mesoporosity and nanocrystallinity of the semiconductor are important not only because of the large amount of dye that can be adsorbed on the system's very large surface, but also for two additional reasons: (1) it allows the semiconductor small particles to become almost totally depleted upon immersion in the electrolyte (allowing for large photovoltages), and (2) the proximity of the electrolyte to all particles modes screening of injected electrons, and thus their transport, possible.

  16. Let-7 Sensitizes KRAS Mutant Tumor Cells to Chemotherapy

    PubMed Central

    Dai, Xin; Jiang, Ying; Tan, Chalet

    2015-01-01

    KRAS is the most commonly mutated oncogene in human cancers and is associated with poor prognosis and drug resistance. Let-7 is a family of tumor suppressor microRNAs that are frequently suppressed in solid tumors, where KRAS mutations are highly prevalent. In this study, we investigated the potential use of let-7 as a chemosensitizer. We found that let-7b repletion selectively sensitized KRAS mutant tumor cells to the cytotoxicity of paclitaxel and gemcitabine. Transfection of let-7b mimic downregulated the expression of mutant but not wild-type KRAS. Combination of let-7b mimic with paclitaxel or gemcitabine diminished MEK/ERK and PI3K/AKT signaling concurrently, triggered the onset of apoptosis, and reverted the epithelial-mesenchymal transition in KRAS mutant tumor cells. In addition, let-7b repletion downregulated the expression of β-tubulin III and ribonucleotide reductase subunit M2, two proteins known to mediate tumor resistance to paclitaxel and gemcitabine, respectively. Let-7 may represent a new class of chemosensitizer for the treatment of KRAS mutant tumors. PMID:25946136

  17. Gene expressions changes in bronchial epithelial cells: markers for respiratory sensitizers and exploration of the NRF2 pathway.

    PubMed

    Remy, Sylvie; Verstraelen, Sandra; Van Den Heuvel, Rosette; Nelissen, Inge; Lambrechts, Nathalie; Hooyberghs, Jef; Schoeters, Greet

    2014-03-01

    For the classification of respiratory sensitizing chemicals, no validated in vivo nor in vitro tests are currently available. In this study, we evaluated whether respiratory sensitizers trigger specific signals in human bronchial epithelial (BEAS-2B) cells at the level of the transcriptome. The cells were exposed during 6, 10, and 24h to 4 respiratory sensitizers and 6 non-respiratory sensitizers (3 skin sensitizers and 3 respiratory irritants) at a concentration inducing 20% cell viability loss after 24h. Changes in gene expression were evaluated using Agilent Whole Human Genome 4×44K oligonucleotide arrays. A limited number of 11 transcripts could be identified as potential biomarkers to identify respiratory sensitizers. Three of these transcripts are associated to immune system processes (HSPA5, UPP1, and SEPRINE1). In addition, the transcriptome was screened for transcripts that are differentially expressed compared to vehicle control for each chemical. The results show that the NRF2-mediated oxidative stress response is activated in the cell line after stimulation with all of the chemicals that were selected in our study, and that - at the level of gene expression - this pathway shows no potential to discriminate between any of the three compound groups: respiratory sensitizers, skin sensitizers, or electrophilic respiratory irritants. PMID:24211530

  18. Constitutive Lck Activity Drives Sensitivity Differences between CD8+ Memory T Cell Subsets.

    PubMed

    Moogk, Duane; Zhong, Shi; Yu, Zhiya; Liadi, Ivan; Rittase, William; Fang, Victoria; Dougherty, Janna; Perez-Garcia, Arianne; Osman, Iman; Zhu, Cheng; Varadarajan, Navin; Restifo, Nicholas P; Frey, Alan B; Krogsgaard, Michelle

    2016-07-15

    CD8(+) T cells develop increased sensitivity following Ag experience, and differences in sensitivity exist between T cell memory subsets. How differential TCR signaling between memory subsets contributes to sensitivity differences is unclear. We show in mouse effector memory T cells (TEM) that >50% of lymphocyte-specific protein tyrosine kinase (Lck) exists in a constitutively active conformation, compared with <20% in central memory T cells (TCM). Immediately proximal to Lck signaling, we observed enhanced Zap-70 phosphorylation in TEM following TCR ligation compared with TCM Furthermore, we observed superior cytotoxic effector function in TEM compared with TCM, and we provide evidence that this results from a lower probability of TCM reaching threshold signaling owing to the decreased magnitude of TCR-proximal signaling. We provide evidence that the differences in Lck constitutive activity between CD8(+) TCM and TEM are due to differential regulation by SH2 domain-containing phosphatase-1 (Shp-1) and C-terminal Src kinase, and we use modeling of early TCR signaling to reveal the significance of these differences. We show that inhibition of Shp-1 results in increased constitutive Lck activity in TCM to levels similar to TEM, as well as increased cytotoxic effector function in TCM Collectively, this work demonstrates a role for constitutive Lck activity in controlling Ag sensitivity, and it suggests that differential activities of TCR-proximal signaling components may contribute to establishing the divergent effector properties of TCM and TEM. This work also identifies Shp-1 as a potential target to improve the cytotoxic effector functions of TCM for adoptive cell therapy applications. PMID:27271569

  19. Cell Lineages and the Logic of Proliferative Control

    PubMed Central

    Wan, Frederic Y. M; Nie, Qing; Calof, Anne L

    2009-01-01

    It is widely accepted that the growth and regeneration of tissues and organs is tightly controlled. Although experimental studies are beginning to reveal molecular mechanisms underlying such control, there is still very little known about the control strategies themselves. Here, we consider how secreted negative feedback factors (“chalones”) may be used to control the output of multistage cell lineages, as exemplified by the actions of GDF11 and activin in a self-renewing neural tissue, the mammalian olfactory epithelium (OE). We begin by specifying performance objectives—what, precisely, is being controlled, and to what degree—and go on to calculate how well different types of feedback configurations, feedback sensitivities, and tissue architectures achieve control. Ultimately, we show that many features of the OE—the number of feedback loops, the cellular processes targeted by feedback, even the location of progenitor cells within the tissue—fit with expectations for the best possible control. In so doing, we also show that certain distinctions that are commonly drawn among cells and molecules—such as whether a cell is a stem cell or transit-amplifying cell, or whether a molecule is a growth inhibitor or stimulator—may be the consequences of control, and not a reflection of intrinsic differences in cellular or molecular character. PMID:19166268

  20. Titania nanobundle networks as dye-sensitized solar cell photoanodes

    NASA Astrophysics Data System (ADS)

    Dong, Cunku; Xiang, Wanchun; Huang, Fuzhi; Fu, Dongchuan; Huang, Wenchao; Bach, Udo; Cheng, Yi-Bing; Li, Xin; Spiccia, Leone

    2014-03-01

    Quasi-one-dimensional (1D) titania nanobundles were synthesized via a hydrothermal method and used to print random network nanostructured films. These films are shown to be ideally suited for application as photoanodes in dye-sensitized solar cells (DSCs) as they have a higher porosity compared to the traditional 1D nanostructured TiO2 materials. Devices constructed using the N719 dye and iodide/triiodide as the redox mediator in the electrolyte yielded energy conversion efficiencies (η = 6.1 +/- 0.2%), which were marginally lower than for devices made with the commonly used P25 titania films (η = 6.3 +/- 0.1%) under one sun simulated solar radiation. Application of an electrolyte based on the [Co(bpy)3]2+/3+ redox couple and the MK2 organic sensitizer resulted in higher efficiencies (η = 7.70 +/- 0.1%) than for the P25 devices (η = 6.3 +/- 0.3%). Each performance parameter (short circuit current density, open circuit voltage and fill factor) was higher for the TiO2 nanobundle devices than those for the P25-based devices. The results of electrochemical impedance spectroscopy (EIS), intensity-modulated photovoltage spectroscopy (IMVS), and dye-loading measurements indicated that the better performance of TiO2 nanobundle devices with cobalt electrolytes correlates with higher porosity, relatively fast electron transport and more efficient suppression of electron recombination. A faster rate of diffusion of the cobalt complexes through the highly porous TiO2 nanobundle network is proposed to contribute to the enhanced device efficiency.Quasi-one-dimensional (1D) titania nanobundles were synthesized via a hydrothermal method and used to print random network nanostructured films. These films are shown to be ideally suited for application as photoanodes in dye-sensitized solar cells (DSCs) as they have a higher porosity compared to the traditional 1D nanostructured TiO2 materials. Devices constructed using the N719 dye and iodide/triiodide as the redox mediator in

  1. Fuel cell with internal flow control

    SciTech Connect

    Haltiner, Jr., Karl J.; Venkiteswaran, Arun

    2012-06-12

    A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

  2. Imaging structure sensitive catalysis on different shape-controlled platinum nanoparticles.

    PubMed

    Sánchez-Sánchez, Carlos M; Solla-Gullón, José; Vidal-Iglesias, Francisco J; Aldaz, Antonio; Montiel, Vicente; Herrero, Enrique

    2010-04-28

    The structure sensitive catalytic activity for oxygen reduction reaction (ORR) on shape-controlled Pt nanoparticles (NPs) is directly imaged using scanning electrochemical microscopy (SECM). We synthesize and compare four types of Pt NPs: spherical, cubic, hexagonal, and tetrahedral-octahedral. Our SECM images show the hexagonal Pt NPs displaying the highest activity for ORR in two acid electrolytes. Meanwhile, cubic and tetrahedral-octahedral NPs drastically change their activity depending on specific adsorption of the different anions in solution. The NPs morphology produces predominant crystallographic planes at the surface of these shape-controlled Pt NPs, which are responsible for their different catalytic activity. Our results translate the studies on Pt single crystal electrodes present in the literature into Pt NPs that are useful as a catalyst in real fuel cells. PMID:20359217

  3. Quality Assurance in the Polio Laboratory. Cell Sensitivity and Cell Authentication Assays.

    PubMed

    Dunn, Glynis

    2016-01-01

    The accuracy of poliovirus surveillance is largely dependent on the quality of the cell lines used for virus isolation, which is the foundation of poliovirus diagnostic work. Many cell lines are available for the isolation of enteroviruses, whilst genetically modified L20B cells can be used as a diagnostic tool for the identification of polioviruses. To be confident that cells can consistently isolate the virus of interest, it is necessary to have a quality assurance system in place, which will ensure that the cells in use are not contaminated with other cell lines or microorganisms and that they remain sensitive to the viruses being studied.The sensitivity of cell lines can be assessed by the regular testing of a virus standard of known titer in the cell lines used for virus isolation. The titers obtained are compared to previously obtained titers in the same assay, so that any loss of sensitivity can be detected.However, the detection of cell line cross contamination is more difficult. DNA bar coding is a technique that uses a short DNA sequence from a standardized position in the genome as a molecular diagnostic assay for species-level identification. For almost all groups of higher animals, the cytochrome c oxidase subunit 1 of mitochondrial DNA (CO1) is emerging as the standard barcode region. This region is 648 nucleotide base pairs long in most phylogenetic groups and is flanked by regions of conserved sequences, making it relatively easy to isolate and analyze. DNA barcodes vary among individuals of the same species to a very minor degree (generally less than 1-2 %), and a growing number of studies have shown that the COI sequences of even closely related species differ by several per cent, making it possible to identify different species with high confidence. PMID:26983732

  4. Predictors of sensitivity to chemoradiotherapy of esophageal squamous cell carcinoma.

    PubMed

    Yi, Yan; Li, Baosheng; Sun, Hongfu; Zhang, Zicheng; Gong, Heyi; Li, Hongsheng; Huang, Wei; Wang, Zhongtang

    2010-08-01

    The purpose of this study was to investigate clinical-biological factors which could predict the sensitivity to chemoradiotherapy of esophageal squamous cell carcinoma (ESCC). One hundred eighty-one patients with stages I-IV ESCC were evaluated. The cytokeratin 19 fragment antigen 21-1 (CYFRA21-1), carcinoembryonic antigen (CEA), albumin (A) as well as hemoglobin (HB) concentration were measured before the initiation of chemoradiotherapy (CRT). The cutoff values of CYFRA21-1, CEA, and A were defined as 3.4 ng/ml, 3.3 ng/ml, 3.5 g/dl, respectively. HB was divided into three levels: <12.0, 12.0-14.0, and >14.0 g/dl. Clinical factors such as sex, age, tumor location, primary cancer length, and tumor-node-metastasis stage were also evaluated. The effective rate (complete response + partial response) of the primary tumor estimated by computed tomography was 60.71% (17 out of 28) in patients with CEA high group while 92.54% (62 out of 67) in patients with CEA low group (P = 0.000) and 62.50% (20 out of 32) in patients with CYFRA21-1 high group while 92.98% (53 out of 57) in patients with CYFRA21-1 low group (P = 0.000). HB levels before and during CRT were also associated with the effectiveness (P = 0.005, 0.033, respectively). HB levels before CRT at 12.0-14.0 g/dl were associated with the best effectiveness, followed by >14.0 and <12.0 g/dl (effective rates 88.89% vs. 83.75%, 62.07%, respectively, P = 0.005). HB levels during CRT also showed similar results (effective rates 87.80% vs. 85.41%, 70.59%, respectively, P = 0.033). Furthermore, according to numbers of the above risk factors, the sensitivity of CRT was higher in patients with zero to one risk factors than those with two to four risk factors (P = 0.023). CYFRA21-1 and CEA as well as HB and their combination may be helpful in predicting the sensitivity to CRT of ESCC. However, the results should be further confirmed in larger, more homogeneous studies.

  5. IDO Downregulation Induces Sensitivity to Pemetrexed, Gemcitabine, FK866, and Methoxyamine in Human Cancer Cells.

    PubMed

    Maleki Vareki, Saman; Chen, Di; Di Cresce, Christine; Ferguson, Peter J; Figueredo, Rene; Pampillo, Macarena; Rytelewski, Mateusz; Vincent, Mark; Min, Weiping; Zheng, Xiufen; Koropatnick, James

    2015-01-01

    Indoleamine 2,3-dioxygenase-1 (IDO) is an immune regulatory enzyme expressed by most human tumors. IDO levels in tumor cells correlate with increased metastasis and poor patient outcome and IDO is linked to tumor cell resistance to immunotherapy, radiation therapy, and chemotherapy. Knowledge of tumor cell-autonomous effects of IDO, independent of its well-known role in regulating and suppressing anti-tumor immune responses, is limited. Clonal populations of A549 human lung adenocarcinoma cells stably transfected with anti-IDO shRNA or scrambled control shRNA were used to study IDO effects on drug sensitivity and resistance. IFNγ was used to induce IDO in those cells. We show, for the first time, that IDO mediates human tumor cell resistance to the candidate anticancer drugs FK866 (an NAD+ inhibitor), methoxyamine (MX, a base excision repair [BER] inhibitor) and approved anticancer drugs pemetrexed (a folate anti-metabolite) and gemcitabine (a nucleoside analogue), and combined treatment with pemetrexed and MX, in the absence of immune cells. Concurrent knockdown of IDO and thymidylate synthase (TS, a key rate-limiting enzyme in DNA synthesis and repair) sensitizes human lung cancer cells to pemetrexed and 5FUdR to a greater degree than knockdown of either target alone. We conclude that BER in IDO-expressing A549 cells plays a major role in mediating resistance to a range of approved and candidate anticancer drugs. IDO inhibitors are undergoing clinical trials primarily to improve antitumor immune responses. We show that targeting IDO alone or in combination with TS is a potentially valuable therapeutic strategy for cancer treatment, independent of immune activity and in combination with conventional chemotherapy.

  6. PES1 regulates sensitivity of colorectal cancer cells to anticancer drugs

    SciTech Connect

    Xie, Wei; Qu, Like; Meng, Lin; Liu, Caiyun; Wu, Jian; Shou, Chengchao

    2013-02-15

    Highlights: ► PES1 was overexpressed in diverse cancer cell lines. ► PES1-ablation enhances DNA damage response by decreasing DNA repair. ► PES1-ablation increases the sensitivity of HCT116 cells to chemotherapeutic agents. ► PES1-ablation is associated with diminished nuclear entry of RAD51. -- Abstract: PES1 (also known as Pescadillo), a nucleolar protein, was involved in biogenesis of ribosomal RNA. Up-regulation of PES1 has been documented in some human cancers, indicating that PES1 may play some crucial roles in tumorigenesis. In our previous study, it was found that silencing of PES1 resulted in decreased proliferation of colorectal cancer cells. We also noticed that depletion of PES1 altered expression profiles of diverse genes. In the present study, we validated the expression changes of a subset of genotoxic stress-related genes in PES1-silenced HCT116 cells by quantitative RT-PCR. The steady and etoposide-induced phosphorylated H2AX (γ-H2AX) were higher in PES1-silenced cells than in control cells. Besides, etoposide-induced γ-H2AX persisted longer in PES1-silenced cells after removing the etoposide. Next, results of comet assay revealed decreased DNA repair after PES1-ablation. PES1-ablated cells were more sensitive to chemotherapeutic agents, which could be reversed by reconstitution with exogenous PES1. Furthermore, deletion of PES1 diminished steady and DNA damage-induced levels of nuclear RAD51. Our results uncover a potential role of PES1 in chemoresistance by regulating DNA damage response in colorectal cancer cells.

  7. FTIR Biospectroscopy Investigation on Cisplatin Cytotoxicity in Three Pairs of Sensitive and Resistant Cell Line.

    PubMed

    Farhadi, Ensieh; Kobarfard, Farzad; H Shirazi, Farshad

    2016-01-01

    Fourier Transformed Infrared Spectroscopy (FTIR) has extensively been used for biological applications. Cisplatin is one the most useful antineoplastic chemotherapy drugs for a variety of different human cancers. One of the clinical problems in its application, which would consequently affect the therapeutic outcome of its application, is the occurrence of resistance to this agent. In this project three different pairs of sensitive and resistant cell lines of human ovarian A2780 and its resistant pair of A2780-CP, human ovarian OV2008 and its resistant pair of C13, and finally human lung carcinoma of HTB56 and its resistant pair of HTB56-CP were grown in the laboratory under the standard procedure. Saline was exposed to control cells, whereas 1, 5 and 10 µg/mL of cisplatin was exposed to experimental cells, for 1 h. Cells were then collected and lyophilized from which spectra were taken. According to our results, we could not trigger a well-recognized cells biomolecular band at 1015 cm(-1), being modified after exposure to cisplatin in all cell lines. On the other hand, there was a clear dose-dependent increase in protein β-sheet structure related peaks shift in resistant cell lines after exposure to cisplatin. This would probably indicate an easier protein interaction site for cisplatin in the resistant cell lines, which would probably inhibit cisplatin from binding to DNA, as the cytotoxic target. As a conclusion, FTIR biospectroscopy has proven its potency to identify the interactions, as well as the false engagement cellular sites for cisplatin in sensitive and resistant cell lines. PMID:27610161

  8. FTIR Biospectroscopy Investigation on Cisplatin Cytotoxicity in Three Pairs of Sensitive and Resistant Cell Line

    PubMed Central

    Farhadi, Ensieh; Kobarfard, Farzad; H. Shirazi, Farshad

    2016-01-01

    Fourier Transformed Infrared Spectroscopy (FTIR) has extensively been used for biological applications. Cisplatin is one the most useful antineoplastic chemotherapy drugs for a variety of different human cancers. One of the clinical problems in its application, which would consequently affect the therapeutic outcome of its application, is the occurrence of resistance to this agent. In this project three different pairs of sensitive and resistant cell lines of human ovarian A2780 and its resistant pair of A2780-CP, human ovarian OV2008 and its resistant pair of C13, and finally human lung carcinoma of HTB56 and its resistant pair of HTB56-CP were grown in the laboratory under the standard procedure. Saline was exposed to control cells, whereas 1, 5 and 10 µg/mL of cisplatin was exposed to experimental cells, for 1 h. Cells were then collected and lyophilized from which spectra were taken. According to our results, we could not trigger a well-recognized cells biomolecular band at 1015 cm-1, being modified after exposure to cisplatin in all cell lines. On the other hand, there was a clear dose-dependent increase in protein β-sheet structure related peaks shift in resistant cell lines after exposure to cisplatin. This would probably indicate an easier protein interaction site for cisplatin in the resistant cell lines, which would probably inhibit cisplatin from binding to DNA, as the cytotoxic target. As a conclusion, FTIR biospectroscopy has proven its potency to identify the interactions, as well as the false engagement cellular sites for cisplatin in sensitive and resistant cell lines. PMID:27610161

  9. Pressure-Sensitive System for Gas-Temperature Control

    NASA Technical Reports Server (NTRS)

    Cesaro, Richard S; Matz, Norman

    1948-01-01

    A thermodynamic relation is derived and simplified for use as a temperature-limiting control equation involving measurement of gas temperature before combustion and gas pressures before and after combustion. For critical flow in the turbine nozzles of gas-turbine engines, the control equation is further simplified to require only measurements upstream of the burner. Hypothetical control systems are discussed to illustrate application of the control equations.

  10. Results of an integrated structure-control law design sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.

    1988-01-01

    Next generation air and space vehicle designs are driven by increased performance requirements, demanding a high level of design integration between traditionally separate design disciplines. Interdisciplinary analysis capabilities have been developed, for aeroservoelastic aircraft and large flexible spacecraft control for instance, but the requisite integrated design methods are only beginning to be developed. One integrated design method which has received attention is based on hierarchal problem decompositions, optimization, and design sensitivity analyses. This paper highlights a design sensitivity analysis method for Linear Quadratic Cost, Gaussian (LQG) optimal control laws, which predicts change in the optimal control law due to changes in fixed problem parameters using analytical sensitivity equations. Numerical results of a design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimally controlled aircraft's response to various problem formulation and physical aircraft parameters is determined. These results are used to predict the aircraft's new optimally controlled response if the parameter was to have some other nominal value during the control law design process. The sensitivity results are validated by recomputing the optimal control law for discrete variations in parameters, computing the new actual aircraft response, and comparing with the predicted response. These results show an improvement in sensitivity accuracy for integrated design purposes over methods which do not include changess in the optimal control law. Use of the analytical LQG sensitivity expressions is also shown to be more efficient that finite difference methods for the computation of the equivalent sensitivity information.

  11. Overexpression of salivary-type amylase reduces the sensitivity to bortezomib in multiple myeloma cells.

    PubMed

    Mizuno, Shohei; Hanamura, Ichiro; Ota, Akinobu; Karnan, Sivasundaram; Narita, Tomoko; Ri, Masaki; Mizutani, Motonori; Goto, Mineaki; Gotou, Mayuko; Tsunekawa, Norikazu; Shikami, Masato; Iida, Shinsuke; Hosokawa, Yoshitaka; Miwa, Hiroshi; Ueda, Ryuzo; Nitta, Masakazu; Takami, Akiyoshi

    2015-11-01

    Amylase-producing myeloma exhibits refractoriness to chemotherapy and a dismal prognosis. In this study, we established a human myeloma cell line, 8226/AMY1, in which a lentivirally transfected AMY1 gene was stably expressed and explored its biological characteristics. 8226/AMY1 showed a survival advantage over mock control when treated with dexamethasone, bortezomib, and lenalidomide in vitro partly through inhibition of apoptosis induced by these reagents. In a xenograft murine model, 8226/AMY1 showed rapid tumor growth and reduced sensitivity to bortezomib compared with mock. A microarray gene expression analysis identified TCL1A, which functions as a coactivator of the cell survival kinase Akt, differentially up-regulated in 8226/AMY1. The expression of phosphorylated Akt was increased in the 8226/AMY1 cells following bortezomib treatment, but not in the mock cells. In addition, treatment with perifosine, an inhibitor of Akt phosphorylation, enhanced the anti-myeloma effect of bortezomib in the 8226/AMY1 cells. Our data suggest that amylase-producing myeloma reduced the sensitivity to bortezomib in vitro and in vivo, and the up-regulation of TCL1A may influence the drug susceptibility of 8226/AMY1 via the phosphorylation of Akt. These findings provide clues for developing treatment approaches for not only amylase-producing myeloma, but also relapsed and refractory myelomas.

  12. IL-35 over-expression increases apoptosis sensitivity and suppresses cell growth in human cancer cells.

    PubMed

    Long, Jun; Zhang, Xulong; Wen, Mingjie; Kong, Qingli; Lv, Zhe; An, Yunqing; Wei, Xiao-Qing

    2013-01-01

    Interleukin (IL)-35 is a novel heterodimeric cytokine in the IL-12 family and is composed of two subunits: Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35. IL-35 is expressed in T regulatory (Treg) cells and contributes to the immune suppression function of these cells. In contrast, we found that both IL-35 subunits were expressed concurrently in most human cancer cell lines compared to normal cell lines. In addition, we found that TNF-α and IFN-γ stimulation led to increased IL-35 expression in human cancer cells. Furthermore, over-expression of IL-35 in human cancer cells suppressed cell growth in vitro, induced cell cycle arrest at the G1 phase, and mediated robust apoptosis induced by serum starvation, TNF-α, and IFN-γ stimulation through the up-regulation of Fas and concurrent down-regulation of cyclinD1, survivin, and Bcl-2 expression. In conclusion, our results reveal a novel functional role for IL-35 in suppressing cancer activity, inhibiting cancer cell growth, and increasing the apoptosis sensitivity of human cancer cells through the regulation of genes related to the cell cycle and apoptosis. Thus, this research provides new insights into IL-35 function and presents a possible target for the development of novel cancer therapies.

  13. Sensitization of acute lymphoblastic leukemia cells for LCL161-induced cell death by targeting redox homeostasis.

    PubMed

    Haß, Christina; Belz, Katharina; Schoeneberger, Hannah; Fulda, Simone

    2016-04-01

    Disturbed redox homeostasis with both elevated reactive oxygen species (ROS) levels and antioxidant defense mechanisms has been reported in acute lymphoblastic leukemia (ALL). We therefore hypothesized that inhibition of pathways responsible for ROS detoxification renders ALL cells more susceptible for cell death. Here, we report that pharmacological inhibitors of key pathways for the elimination of ROS, i.e. Erastin, buthionine sulfoximine (BSO) and Auranofin, sensitize ALL cells for cell death upon treatment with the Smac mimetic LCL161 that antagonizes Inhibitor of Apoptosis (IAP) proteins. Erastin, BSO or Auranofin significantly increase LCL161-induced cell death and also act in concert with LCL161 to profoundly suppress long-term clonogenic survival in several ALL cell lines. Erastin or BSO cooperates with LCL161 to stimulate ROS production and lipid peroxidation prior to cell death. ROS production and lipid peroxidation are required for this cotreatment-induced cell death, since ROS scavengers or pharmacological inhibition of lipid peroxidation provides significant protection against cell death. These results emphasize that inhibition of antioxidant defense mechanisms can serve as a potent approach to prime ALL cells for LCL161-induced cell death.

  14. Pomegranate leaves and mulberry fruit as natural sensitizers for dye-sensitized solar cells

    SciTech Connect

    Chang, Ho; Lo, Yu-Jen

    2010-10-15

    This study employs chlorophyll extract from pomegranate leaf and anthocyanin extract from mulberry fruit as the natural dyes for a dye-sensitized solar cell (DSSC). A self-developed nanofluid synthesis system is employed to prepare TiO{sub 2} nanofluid with an average particle size of 25 nm. Electrophoresis deposition was performed to deposit TiO{sub 2} nanoparticles on the indium tin oxide (ITO) conductive glass, forming a TiO{sub 2} thin film with the thickness of 11 {mu}m. Furthermore, this TiO{sub 2} thin film was sintered at 450 C to enhance the thin film compactness. Sputtering was used to prepare counter electrode by depositing Pt thin film on FTO glass at a thickness of 20 nm. The electrodes, electrolyte (I{sub 3}{sup -}), and dyes were assembled into a cell module and illuminated by a light source simulating AM 1.5 with a light strength of 100 mW/cm{sup 2} to measure the photoelectric conversion efficiency of the prepared DSSCs. According to experimental results, the conversion efficiency of the DSSCs prepared by chlorophyll dyes from pomegranate leaf extract is 0.597%, with open-circuit voltage (V{sub OC}) of 0.56 V, short-circuit current density (J{sub SC}) of 2.05 mA/cm{sup 2}, and fill factor (FF) of 0.52. The conversion efficiency of the DSSCs prepared by anthocyanin dyes from mulberry extract is 0.548%, with V{sub OC} of 0.555 V and J{sub SC} of 1.89 mA/cm{sup 2} and FF of 0.53. The conversion efficiency is 0.722% for chlorophyll and anthocyanin as the dye mixture, with V{sub OC} of 0.53 V, J{sub SC} of 2.8 mA/cm{sup 2}, and FF of 0.49. (author)

  15. Cell Patterning Chip for Controlling the Stem Cell Microenvironment

    PubMed Central

    Rosenthal, Adam; Macdonald, Alice; Voldman, Joel

    2007-01-01

    Cell-cell signaling is an important component of the stem cell microenvironment, affecting both differentiation and self-renewal. However, traditional cell-culture techniques do not provide precise control over cell-cell interactions, while existing cell patterning technologies are limited when used with proliferating or motile cells. To address these limitations, we created the Bio Flip Chip (BFC), a microfabricated polymer chip containing thousands of microwells, each sized to trap down to a single stem cell. We have demonstrated the functionality of the BFC by patterning a 50×50 grid of murine embryonic stem cells (mESCs), with patterning efficiencies > 75%, onto a variety of substrates – a cell-culture dish patterned with gelatin, a 3-D substrate, and even another layer of cells. We also used the BFC to pattern small groups of cells, with and without cell-cell contact, allowing incremental and independent control of contact-mediated signaling. We present quantitative evidence that cell-cell contact plays an important role in depressing mESC colony formation, and show that E-cadherin is involved in this negative regulatory pathway. Thus, by allowing exquisite control of the cellular microenvironment, we provide a technology that enables new applications in tissue engineering and regenerative medicine. PMID:17434582

  16. Bcl-2high mantle cell lymphoma cells are sensitized to acadesine with ABT-199

    PubMed Central

    Montraveta, Arnau; Xargay-Torrent, Sílvia; Rosich, Laia; López-Guerra, Mònica; Roldán, Jocabed; Rodríguez, Vanina; Lee-Vergés, Eriong; de Frías, Mercè; Campàs, Clara; Campo, Elias; Roué, Gaël; Colomer, Dolors

    2015-01-01

    Acadesine is a nucleoside analogue with known activity against B-cell malignancies. Herein, we showed that in mantle cell lymphoma (MCL) cells acadesine induced caspase-dependent apoptosis through turning on the mitochondrial apoptotic machinery. At the molecular level, the compound triggered the activation of the AMPK pathway, consequently modulating known downstream targets, such as mTOR and the cell motility-related vasodilator-stimulated phosphoprotein (VASP). VASP phosphorylation by acadesine was concomitant with a blockade of CXCL12-induced migration. The inhibition of the mTOR cascade by acadesine, committed MCL cells to enter in apoptosis by a translational downregulation of the antiapoptotic Mcl-1 protein. In contrast, Bcl-2 protein levels were unaffected by acadesine and MCL samples expressing high levels of Bcl-2 tended to have a reduced response to the drug. Targeting Bcl-2 with the selective BH3-mimetic agent ABT-199 sensitized Bcl-2 high MCL cells to acadesine. This effect was validated in vivo, where the combination of both agents displayed a more marked inhibition of tumor outgrowth than each drug alone. These findings support the notions that antiapoptotic proteins of the Bcl-2 family regulate MCL cell sensitivity to acadesine and that the combination of this agent with Bcl-2 inhibitors might be an interesting therapeutic option to treat MCL patients. PMID:26110568

  17. Gingerol sensitizes TRAIL-induced apoptotic cell death of glioblastoma cells

    SciTech Connect

    Lee, Dae-Hee; Kim, Dong-Wook; Jung, Chang-Hwa; Lee, Yong J.; Park, Daeho

    2014-09-15

    Glioblastoma multiforme (GBM) is the most lethal and aggressive astrocytoma of primary brain tumors in adults. Although there are many clinical trials to induce the cell death of glioblastoma cells, most glioblastoma cells have been reported to be resistant to TRAIL-induced apoptosis. Here, we showed that gingerol as a major component of ginger can induce TRAIL-mediated apoptosis of glioblastoma. Gingerol increased death receptor (DR) 5 levels in a p53-dependent manner. Furthermore, gingerol decreased the expression level of anti-apoptotic proteins (survivin, c-FLIP, Bcl-2, and XIAP) and increased pro-apoptotic protein, Bax and truncate Bid, by generating reactive oxygen species (ROS). We also found that the sensitizing effects of gingerol in TRAIL-induced cell death were blocked by scavenging ROS or overexpressing anti-apoptotic protein (Bcl-2). Therefore, we showed the functions of gingerol as a sensitizing agent to induce cell death of TRAIL-resistant glioblastoma cells. This study gives rise to the possibility of applying gingerol as an anti-tumor agent that can be used for the purpose of combination treatment with TRAIL in TRAIL-resistant glioblastoma tumor therapy. - Highlights: • Most GBM cells have been reported to be resistant to TRAIL-induced apoptosis. • Gingerol enhances the expression level of anti-apoptotic proteins by ROS. • Gingerol enhances TRAIL-induced apoptosis through actions on the ROS–Bcl2 pathway.

  18. NANOPATTERNED INTERFACES FOR CONTROLLING CELL BEHAVIOR

    PubMed Central

    CHUNG, KEVIN; DeQUACH, JESSICA A.; CHRISTMAN, KAREN L.

    2013-01-01

    Many studies have demonstrated that microscale changes to surface chemistry and topography affect cell adhesion, proliferation, differentiation, and gene expression. More recently, studies have begun to examine cell behavior interactions with structures on the nanoscale since in vivo, cells recognize and adhere to cell adhesion receptors that are spatially organized on this scale. These studies have been enabled through various fabrication methods, many of which were initially developed for the semiconductor industry. This review explores cell responses to a variety of controlled topographical and biochemical cues using an assortment of nanoscale fabrication methods in order to elucidate which pattern dimensions are beneficial for controlling cell adhesion and differentiation. PMID:25383101

  19. Cubic titanium dioxide photoanode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Chae, Jinho; Kang, Misook

    Following from the recently evolved concept of significantly improving the photovoltaic efficiency in dye-sensitized solar cells (DSSCs) by reducing the loss of electrons on the spherical surface of titanium dioxide, this study examines the synthesis of cubic TiO 2 with a special morphology to overcome this electron loss and investigates its application to DSSCs. Cubic TiO 2 is synthesized by an advanced rapid hydrothermal method, with the addition of an amine species additive. Transmission electron microscopy (TEM) images confirm the cubic shape of the TiO 2 particles with a diameter less than 5-10 nm. Using N719 dye under illumination with 100 mW cm -2 simulated sunlight, the application of cubic TiO 2 to DSSCs affords an energy conversion efficiency of approximately 9.77% (4.0-μm thick TiO 2 film), which is considerably enhanced compared with that achieved using a commercial, spherical TiO 2. Electrostatic force microscopy (EFM) and impedance analyses reveal that the electrons are transferred more rapidly to the surface of a cubic TiO 2 film than on a spherical TiO 2 film.

  20. Clic4, a novel protein that sensitizes β-cells to apoptosisa

    PubMed Central

    Patel, Dhaval; Ythier, Damien; Brozzi, Flora; Eizirik, Decio L.; Thorens, Bernard

    2015-01-01

    Objectives Chloride intracellular channel protein 4 (Clic4) is a ubiquitously expressed protein involved in multiple cellular processes including cell-cycle control, cell differentiation, and apoptosis. Here, we investigated the role of Clic4 in pancreatic β-cell apoptosis. Methods We used βTC-tet cells and islets from β-cell specific Clic4 knockout mice (βClic4KO) and assessed cytokine-induced apoptosis, Bcl2 family protein expression and stability, and identified Clic4-interacting proteins by co-immunoprecipitation and mass spectrometry analysis. Results We show that cytokines increased Clic4 expression in βTC-tet cells and in mouse islets and siRNA-mediated silencing of Clic4 expression in βTC-tet cells or its genetic inactivation in islets β-cells, reduced cytokine-induced apoptosis. This was associated with increased expression of Bcl-2 and increased expression and phosphorylation of Bad. Measurement of Bcl-2 and Bad half-lives in βTC-tet cells showed that Clic4 silencing increased the stability of these proteins. In primary islets β-cells, absence of Clic4 expression increased Bcl-2 and Bcl-xL expression as well as expression and phosphorylation of Bad. Mass-spectrometry analysis of proteins co-immunoprecipitated with Clic4 from βTC-tet cells showed no association of Clic4 with Bcl-2 family proteins. However, Clic4 co-purified with proteins from the proteasome suggesting a possible role for Clic4 in regulating protein degradation. Conclusions Collectively, our data show that Clic4 is a cytokine-induced gene that sensitizes β-cells to apoptosis by reducing the steady state levels of Bcl-2, Bad and phosphorylated Bad. PMID:25830089

  1. Bortezomib Improves Adoptive T-cell Therapy by Sensitizing Cancer Cells to FasL Cytotoxicity.

    PubMed

    Shanker, Anil; Pellom, Samuel T; Dudimah, Duafalia F; Thounaojam, Menaka C; de Kluyver, Rachel L; Brooks, Alan D; Yagita, Hideo; McVicar, Daniel W; Murphy, William J; Longo, Dan L; Sayers, Thomas J

    2015-12-15

    Cancer immunotherapy shows great promise but many patients fail to show objective responses, including in cancers that can respond well, such as melanoma and renal adenocarcinoma. The proteasome inhibitor bortezomib sensitizes solid tumors to apoptosis in response to TNF-family death ligands. Because T cells provide multiple death ligands at the tumor site, we investigated the effects of bortezomib on T-cell responses in immunotherapy models involving low-avidity antigens. Bortezomib did not affect lymphocyte or tissue-resident CD11c(+)CD8(+) dendritic cell counts in tumor-bearing mice, did not inhibit dendritic cell expression of costimulatory molecules, and did not decrease MHC class I/II-associated antigen presentation to cognate T cells. Rather, bortezomib activated NF-κB p65 in CD8(+) T cells, stabilizing expression of T-cell receptor CD3ζ and IL2 receptor-α, while maintaining IFNγ secretion to improve FasL-mediated tumor lysis. Notably, bortezomib increased tumor cell surface expression of Fas in mice as well as human melanoma tissue from a responsive patient. In renal tumor-bearing immunodeficient Rag2(-/-) mice, bortezomib treatment after adoptive T-cell immunotherapy reduced lung metastases and enhanced host survival. Our findings highlight the potential of proteasome inhibitors to enhance antitumor T-cell function in the context of cancer immunotherapy.

  2. [Effect of cryptotanshinone on imatinib sensitivity and P-glycoprotein expression of chronic myeloid leukemia cells].

    PubMed

    Ge, Yu-qing; Cheng, Ru-bin; Yang, Bo; Huang, Zhen; Chen, Zhe

    2015-06-01

    Cryptotanshinone (CPT), a lipid soluble active compound in Salvia miltiorrhiza, has a significant inhibitory effect on multiple malignant tumors, e. g. chronic myeloid leukemia (CML) cells and can effectively enhance imatinib's chemotherapeutic effect. However, its functional molecular mechanism remained unclear. In this experiment, the authors conducted a systematic study on the effect of CPT on the imatinib sensitivity and P-glycoprotein (P-gp) expression in CML cells by using CML cells K562 and imatinib persister K562-R. The MTT assays were performed to determine CPT's impact on the inhibitory effect of imatinib. Annexin V-FITC/PI staining analysis was used to detect the changes in the cell apoptosis rate. The active changes in apoptosis regulatory proteins Caspase-3, Caspase-9 and PARP were determined by Western blot. After the cells were pretreated with the gradient concentration of CPT, the expression of P-gp was analyzed by Western blot and flow cytometry. The changes in intracellular concentrations of imatinib were determined by HPLC analysis. The results indicated that the pretreatment with CPT significantly increased the proliferation inhibiting and apoptosis inducing effects of imatinib on K562 and K562-R cells as well as the degradation product expression of pro-apoptotic proteins Caspase-3, Caspase-9 and PARP, with a significant difference with the control group (P < 0.01). However, CPT showed no impact on the P-gp expression in CML cells and the intracellular concentrations of imatinib. In summary, the findings suggested that CPT enhanced the sensitivity of CML cells to imatinib. Its mechanism is not dependent on the inhibition in P-gp expression and the increase in intracellular drug concentration. PMID:26591531

  3. Asymmetric cell division during T cell development controls downstream fate

    PubMed Central

    Pham, Kim; Shimoni, Raz; Charnley, Mirren; Ludford-Menting, Mandy J.; Hawkins, Edwin D.; Ramsbottom, Kelly; Oliaro, Jane; Izon, David; Ting, Stephen B.; Reynolds, Joseph; Lythe, Grant; Molina-Paris, Carmen; Melichar, Heather; Robey, Ellen; Humbert, Patrick O.; Gu, Min

    2015-01-01

    During mammalian T cell development, the requirement for expansion of many individual T cell clones, rather than merely expansion of the entire T cell population, suggests a possible role for asymmetric cell division (ACD). We show that ACD of developing T cells controls cell fate through differential inheritance of cell fate determinants Numb and α-Adaptin. ACD occurs specifically during the β-selection stage of T cell development, and subsequent divisions are predominantly symmetric. ACD is controlled by interaction with stromal cells and chemokine receptor signaling and uses a conserved network of polarity regulators. The disruption of polarity by deletion of the polarity regulator, Scribble, or the altered inheritance of fate determinants impacts subsequent fate decisions to influence the numbers of DN4 cells arising after the β-selection checkpoint. These findings indicate that ACD enables the thymic microenvironment to orchestrate fate decisions related to differentiation and self-renewal. PMID:26370500

  4. Imatinib sensitizes endometrial cancer cells to cisplatin by targeting CD117-positive growth-competent cells.

    PubMed

    Zhang, Xiuzhi; Kyo, Satoru; Nakamura, Mitsuhiro; Mizumoto, Yasunari; Maida, Yoshiko; Bono, Yukiko; Takakura, Masahiro; Fujiwara, Hiroshi

    2014-04-01

    The use of molecular target therapy has not been established for endometrial cancer. The present study investigated the potential therapeutic strategy of targeting CD117-positive cancer cells as a novel molecular target therapy. FACS-sorted CD117(+) cells isolated from endometrial cancer cell lines (Ishikawa or MFE280 cells) exhibited higher proliferative capacity in vitro and colony forming activity on soft agar, and decreased sensitivity to cisplatin, compared to CD117(-) cells. Immunohistochemical analyses with surgical specimens of endometrial cancers showed that high CD117 expression was tightly linked to advanced FIGO stages, myometrial invasion and histological grade, and was significantly associated with poor overall survival and relapse-free survival (Kaplan-Meier analysis; p<0.001, log-rank test). The Cox-regression hazard model identified high CD117 expression to be an independent prognostic factor for survival (p<0.05). In vitro assay confirmed that stem cell factor (SCF), a ligand of CD117, was produced specifically in CD117(+) cells of endometrial cancer, and the colony-forming activity were abrogated by adding anti-SCF antibody, indicating an SCF-dependent growth property. Imatinib was confirmed to selectively target CD117(+) cells in vitro, and synergistically enhanced the anti-tumor effect of low dose cisplatin in vivo, which showed only modest effects when used as a single use. These findings suggest that CD117 can be a marker of aggressive behavior of cells as well as an independent prognostic marker in endometrial cancer. Targeting of the SCF/CD117 axis by imatinib sensitized endometrial cancer cells to cisplatin, proposing a novel therapeutic strategy for this tumor type. PMID:24333732

  5. Effects of Dye Structure in Dye Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Hoskins, Anna R.

    Dye sensitized solar cells (DSSCs) are photovoltaic devices that may compete with standard silicon solar cells due to their ease of construction and lower cost [32]. Ruthenium dye structures, such as N3 (Ru -- (4,4' -- dicarboxylic acid -- 2,2' -- bipyridine)2(NCS)2), have shown promise for collection efficiencies near silicon photovoltaic levels [20, 33]. DSSCs have not achieved the reproducibility and maximum efficiency of silicon solar cells [33, 34]. Altering ligands on the dye molecules may affect the energies of light that are absorbed by the DSSC. Photovoltaic testing, including current versus voltage tests, of DSSCs with both narrow band monochromated light sources and broadband (AM1.5 solar simulator) allows comparison between maximum efficiency, short-circuit current, open circuit voltage, and spectral response (SR) for the dye molecules. By studying how the efficiency and power output change with different dye structures, the nature of how to increase efficiency of the DSSC can be addressed. Conjugation length of the ligands in ruthenium dye molecules can be shown, through square-well and Huckel theory calculations, to have a role in changing the HOMO-LUMO gap of the molecules and the absorption of specific wavelengths of light by the DSSC. The efficiency, max power, short circuit current, open circuit voltage, and SR were all measured for the DSSCs at wavelengths from 350 nm to 690 nm using a monochromated light source. Measurements taken at 20 nm steps reveal trends in the photon acceptance for dye molecules that can be linked to the conjugation length of the ligands in the dye through the SR. The change in the SR centroid and UV-VIS measurements indicate a trend toward increasing optimal wavelength with increasing conjugation length in the dye molecules; however these trends are not as pronounced as theoretical calculations for the dyes. This difference in wavelength shift occurs due to the theoretical calculations accounting for only the ligands

  6. Reward and punishment sensitivity and alcohol use: the moderating role of executive control.

    PubMed

    Jonker, Nienke C; Ostafin, Brian D; Glashouwer, Klaske A; van Hemel-Ruiter, Madelon E; de Jong, Peter J

    2014-05-01

    Reward sensitivity and to a lesser extent punishment sensitivity have been found to explain individual differences in alcohol use. Furthermore, many studies showed that addictive behaviors are characterized by impaired self-regulatory processes, and that individual differences related to alcohol use are moderated by executive control. This is the first study that explores the potential moderating role of executive control in the relation between reward and punishment sensitivity and alcohol use. Participants were 76 university students, selected on earlier given information about their alcohol use. Half of the participants indicated to drink little alcohol and half indicated to drink substantial amounts of alcohol. As expected, correlational analyses showed a positive relationship between reward sensitivity and alcohol use and a negative relation between punishment sensitivity and alcohol use. Regression analysis confirmed that reward sensitivity was a significant independent predictor of alcohol use. Executive control moderated the relation between punishment sensitivity and alcohol use, but not the relation between reward sensitivity and alcohol use. Only in individuals with weak executive control punishment sensitivity and alcohol use were negatively related. The results suggest that for individuals with weak executive control, punishment sensitivity might be a protective factor working against substantial alcohol use.

  7. Hierarchical TiO2 photoanode for dye-sensitized solar cells.

    PubMed

    Sauvage, F; Di Fonzo, F; Li Bassi, A; Casari, C S; Russo, V; Divitini, G; Ducati, C; Bottani, C E; Comte, P; Graetzel, M

    2010-07-14

    Hierarchical or one-dimensional architectures are among the most exciting developments in material science these recent years. We present a nanostructured TiO(2) assembly combining these two concepts and resembling a forest composed of individual, high aspect-ratio, treelike nanostructures. We propose to use these structures for the photoanode in dye-sensitized solar cells, and we achieved 4.9% conversion efficiency in combination with C101 dye. We demonstrate this morphology beneficial to hamper the electron recombination and also mass transport control in the mesopores when solvent-free ionic liquid electrolyte is used.

  8. Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells

    NASA Astrophysics Data System (ADS)

    Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

    2016-06-01

    A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

  9. Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells.

    PubMed

    Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

    2016-12-01

    A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells. PMID:27299653

  10. Synthesizing aluminum particles towards controlling electrostatic discharge ignition sensitivity

    SciTech Connect

    Eric S. Collins; Jeffery P. Gesner; Michelle L. Pantoya; Michael A. Daniels

    2014-02-01

    Aluminum particles were synthesized with shell thicknesses ranging from 2.7 to 8.3 nm and a constant diameter of 95 nm. These fuel particles were combined with molybdenum trioxide particles and the electrostatic discharge (ESD) sensitivity of the mixture was measured. Results show ignition delay increased as the alumina shell thickness increased. These results correlated with electrical resistivity measurements of the mixture which increased with alumina concentration. A model was developed using COMSOL for ignition of a single Al particle. The ignition delay in the model was consistent with the experimental results suggesting that the primary ESD ignition mechanism is joule heating.

  11. Downregulation of the autophagy protein ATG-7 correlates with distinct sphingolipid profile in MCF-7 cells sensitized to photodamage

    NASA Astrophysics Data System (ADS)

    Separovic, Duska; Kelekar, Ameeta; Tarca, Adi L.; Bielawski, Jacek; Kessel, David

    2009-06-01

    The objective of this study was to determine the sphingolipid (SL) profile in autophagy-defective cells and overall cell death after PDT with Pc 4 (PDT). Human breast cancer MCF-7 cells with downregulated autophagy protein ATG-7 and their scrambled controls (Scr) were used. Exposure of ATG-7 knockdown cells to PDT led to defective processing of the autophagy marker LC3, and increased overall cell killing. In both cell types PDT evoked an early (2 h) increase in ceramides and dihydroceramides (DHceramides). When the two cell types were compared regarding time (2 and 24 h) and treatment conditions (with and without PDT), the levels of several ceramides and DHceramides were reduced, whereas the concentrations of C14-ceramide, C16-ceramide and C12-DHceramide were higher in ATG-7 knockdown cells. The data imply that the SL profile might be a marker of autophagy-deficiency in cells sensitized to PDT.

  12. Auditory sensitivity provided by self-tuned critical oscillations of hair cells

    NASA Astrophysics Data System (ADS)

    Camalet, Sébastien; Duke, Thomas; Jülicher, Frank; Prost, Jacques

    2000-03-01

    We introduce the concept of self-tuned criticality as a general mechanism for signal detection in sensory systems. In the case of hearing, we argue that active amplification of faint sounds is provided by a dynamical system that is maintained at the threshold of an oscillatory instability. This concept can account for the exquisite sensitivity of the auditory system and its wide dynamic range as well as its capacity to respond selectively to different frequencies. A specific model of sound detection by the hair cells of the inner ear is discussed. We show that a collection of motor proteins within a hair bundle can generate oscillations at a frequency that depends on the elastic properties of the bundle. Simple variation of bundle geometry gives rise to hair cells with characteristic frequencies that span the range of audibility. Tension-gated transduction channels, which primarily serve to detect the motion of a hair bundle, also tune each cell by admitting ions that regulate the motor protein activity. By controlling the bundle's propensity to oscillate, this feedback automatically maintains the system in the operating regime where it is most sensitive to sinusoidal stimuli. The model explains how hair cells can detect sounds that carry less energy than the background noise.

  13. Light-harvesting complexes in photosystem II regulate glutathione-induced sensitivity of Arabidopsis guard cells to abscisic acid.

    PubMed

    Jahan, Md Sarwar; Nozulaidi, Mohd; Khairi, Mohd; Mat, Nashriyah

    2016-05-20

    Light-harvesting complexes (LHCs) in photosystem II (PSII) regulate glutathione (GSH) functions in plants. To investigate whether LHCs control GSH biosynthesis that modifies guard cell abscisic acid (ABA) sensitivity, we evaluated GSH content, stomatal aperture, reactive oxygen species (ROS), weight loss and plant growth using a ch1-1 mutant that was defective of LHCs and compared this with wild-type (WT) Arabidopsis thaliana plants. Glutathione monoethyl ester (GSHmee) increased but 1-chloro-2,4 dinitrobenzene (CDNB) decreased the GSH content in the guard cells. The guard cells of the ch1-1 mutants accumulated significantly less GSH than the WT plants. The guard cells of the ch1-1 mutants also showed higher sensitivity to ABA than the WT plants. The CDNB treatment increased but the GSHmee treatment decreased the ABA sensitivity of the guard cells without affecting ABA-induced ROS production. Dark and light treatments altered the GSH content and stomatal aperture of the guard cells of ch1-1 and WT plants, irrespective of CDNB and GSHmee. The ch1-1 mutant contained fewer guard cells and displayed poor growth, late flowering and stumpy weight loss compared with the WT plants. This study suggests that defective LHCs reduced the GSH content in the guard cells and increased sensitivity to ABA, resulting in stomatal closure.

  14. Light-harvesting complexes in photosystem II regulate glutathione-induced sensitivity of Arabidopsis guard cells to abscisic acid.

    PubMed

    Jahan, Md Sarwar; Nozulaidi, Mohd; Khairi, Mohd; Mat, Nashriyah

    2016-05-20

    Light-harvesting complexes (LHCs) in photosystem II (PSII) regulate glutathione (GSH) functions in plants. To investigate whether LHCs control GSH biosynthesis that modifies guard cell abscisic acid (ABA) sensitivity, we evaluated GSH content, stomatal aperture, reactive oxygen species (ROS), weight loss and plant growth using a ch1-1 mutant that was defective of LHCs and compared this with wild-type (WT) Arabidopsis thaliana plants. Glutathione monoethyl ester (GSHmee) increased but 1-chloro-2,4 dinitrobenzene (CDNB) decreased the GSH content in the guard cells. The guard cells of the ch1-1 mutants accumulated significantly less GSH than the WT plants. The guard cells of the ch1-1 mutants also showed higher sensitivity to ABA than the WT plants. The CDNB treatment increased but the GSHmee treatment decreased the ABA sensitivity of the guard cells without affecting ABA-induced ROS production. Dark and light treatments altered the GSH content and stomatal aperture of the guard cells of ch1-1 and WT plants, irrespective of CDNB and GSHmee. The ch1-1 mutant contained fewer guard cells and displayed poor growth, late flowering and stumpy weight loss compared with the WT plants. This study suggests that defective LHCs reduced the GSH content in the guard cells and increased sensitivity to ABA, resulting in stomatal closure. PMID:26970687

  15. Identification of a novel temperature sensitive promoter in cho cells

    PubMed Central

    2011-01-01

    Background The Chinese hamster ovary (CHO) expression system is the leading production platform for manufacturing biopharmaceuticals for the treatment of numerous human diseases. Efforts to optimize the production process also include the genetic construct encoding the therapeutic gene. Here we report about the successful identification of an endogenous highly active gene promoter obtained from CHO cells which shows conditionally inducible gene expression at reduced temperature. Results Based on CHO microarray expression data abundantly transcribed genes were selected as potential promoter candidates. The S100a6 (calcyclin) and its flanking regions were identified from a genomic CHO-K1 lambda-phage library. Computational analyses showed a predicted TSS, a TATA-box and several TFBSs within the 1.5 kb region upstream the ATG start signal. Various constructs were investigated for promoter activity at 37°C and 33°C in transient luciferase reporter gene assays. Most constructs showed expression levels even higher than the SV40 control and on average a more than two-fold increase at lower temperature. We identified the core promoter sequence (222 bp) comprising two SP1 sites and could show a further increase in activity by duplication of this minimal sequence. Conclusions This novel CHO promoter permits conditionally high-level gene expression. Upon a shift to 33°C, a two to three-fold increase of basal productivity (already higher than SV40 promoter) is achieved. This property is of particular advantage for a process with reduced expression during initial cell growth followed by the production phase at low temperature with a boost in expression. Additionally, production of toxic proteins becomes feasible, since cell metabolism and gene expression do not directly interfere. The CHO S100a6 promoter can be characterized as cold-shock responsive with the potential for improving process performance of mammalian expression systems. PMID:21569433

  16. Process for control of cell division

    NASA Technical Reports Server (NTRS)

    Cone, C. D., Jr. (Inventor)

    1977-01-01

    A method of controlling mitosis of biological cells was developed, which involved inducing a change in the intracellular ionic hierarchy accompanying the cellular electrical transmembrane potential difference (Esubm) of the cells. The ionic hierarchy may be varied by imposing changes on the relative concentrations of Na(+), K(+) and Cl(-), or by directly imposing changes in the physical Esubm level across the cell surface.

  17. Results of an integrated structure/control law design sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.

    1989-01-01

    A design sensitivity analysis method for Linear Quadratic Cost, Gaussian (LQG) optimal control laws, which predicts change in the optimal control law due to changes in fixed problem parameters using analytical sensitivity equations is discussed. Numerical results of a design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimally controlled aircraft's response to various problem formulation and physical aircraft parameters is determined. These results are used to predict the aircraft's new optimally controlled response if the parameter was to have some other nominal value during the control law design process. The sensitivity results are validated by recomputing the optimal control law for discrete variations in parameters, computing the new actual aircraft response, and comparing with the predicted response. These results show an improvement in sensitivity accuracy for integrated design purposes over methods which do not include changes in the optimal control law. Use of the analytical LQG sensitivity expressions is also shown to be more efficient than finite difference methods for the computation of the equivalent sensitivity information.

  18. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy

    PubMed Central

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  19. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

    PubMed

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-07-22

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells.

  20. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-07-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells.

  1. Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

    PubMed

    Ghann, William; Rahman, Aunik; Rahman, Anis; Uddin, Jamal

    2016-01-01

    The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells. PMID:27443236

  2. Theoretical design and screening of alkyne bridged triphenyl zinc porphyrins as sensitizer candidates for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Xianxi; Chen, Qianqian; Sun, Huafei; Pan, Tingting; Hu, Guiqi; Ma, Ruimin; Dou, Jianmin; Li, Dacheng; Pan, Xu

    2014-01-01

    Alkyne bridged porphyrins have been proved very promising sensitizers for dye-sensitized solar cells (DSSCs) with the highest photo-to-electric conversion efficiencies of 11.9% solely and 12.3% co-sensitized with other sensitizers achieved. Developing better porphyrin sensitizers with wider electronic absorption spectra to further improve the efficiencies of corresponding solar cells is still of great significance for the application of DSSCs. A series of triphenyl zinc porphyrins (ZnTriPP) differing in the nature of a pendant acceptor group and the conjugated bridge between the porphyrin nucleus and the acceptor unit were modeled and their electronic and spectral properties calculated using density functional theory. As compared with each other and the experimental results of the compounds used in DSSCs previously, the molecules with a relatively longer conjugative linker and a strong electron-withdrawing group such as cyanide adjacent to the carboxyl acid group seem to provide wider electronic absorption spectra and higher photo-to-electric conversion efficiencies. The dye candidates ZnTriPPE, ZnTriPPM, ZnTriPPQ, ZnTriPPR and ZnTriPPS designed in the current work were found promising to provide comparable photo-to-electric conversion efficiencies to the record 11.9% of the alkyne bridged porphyrin sensitizer YD2-o-C8 reported previously.

  3. Enhanced dye-sensitized solar cell photocurrent and efficiency using a Y-shaped, pyrazine-containing heteroaromatic sensitizer linkage.

    PubMed

    Watson, Brian L; Sherman, Benjamin D; Moore, Ana L; Moore, Thomas A; Gust, Devens

    2015-06-28

    A new sensitizer motif for dye sensitized solar cells (DSSC) has been developed. A heteroaromatic moiety containing a pyrazine ring links two porphyrin chromophores to the metal oxide surface via two carboxylic acid attachment groups. A test DSSC sensitized with the new molecule was 3.5 times more efficient than a similar cell sensitized by a single porphyrin model compound. The open circuit photovoltage was increased by a modest factor of 1.3, but the photocurrent increased by a factor of 2.7. Most of the increase is attributed to a reduced rate of charge recombination of the charge separated state formed by photoinduced electron transfer from the excited sensitizer to the TiO2, although some of the difference is due to increased light absorption resulting from more dye on the photoanode. Increased light absorption due to the pyrazine-containing group may also play a role. The design illustrated here could also be used to link complementary sensitizers or antenna moieties in order to increase spectral coverage.

  4. Novel energy relay dyes for high efficiency dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Mahbubur; Ko, Min Jae; Lee, Jae-Joon

    2015-02-01

    4',6-Diamidino-2-phenylindole (DAPI) and Hoechst 33342 (H33342) were used as novel energy relay dyes (ERDs) for an efficient energy transfer to the N719 dye in I-/I3- based liquid-junction dye-sensitized solar cells (DSSCs). The introduction of the ERDs, either as an additive in the electrolyte or as a co-adsorbent, greatly enhanced the power conversion efficiencies (PCEs), mainly because of an increase in short-circuit current density (Jsc). This was attributed to the effects of non-radiative Förster-type excitation energy transfer as well as the radiative (emission)-type fluorescent energy transfer to the sensitizers. The net PCEs for the N719-sensitized DSSCs with DAPI and H33342 were 10.65% and 10.57%, and showed an improvement of 12.2% and 11.4% over control devices, respectively.4',6-Diamidino-2-phenylindole (DAPI) and Hoechst 33342 (H33342) were used as novel energy relay dyes (ERDs) for an efficient energy transfer to the N719 dye in I-/I3- based liquid-junction dye-sensitized solar cells (DSSCs). The introduction of the ERDs, either as an additive in the electrolyte or as a co-adsorbent, greatly enhanced the power conversion efficiencies (PCEs), mainly because of an increase in short-circuit current density (Jsc). This was attributed to the effects of non-radiative Förster-type excitation energy transfer as well as the radiative (emission)-type fluorescent energy transfer to the sensitizers. The net PCEs for the N719-sensitized DSSCs with DAPI and H33342 were 10.65% and 10.57%, and showed an improvement of 12.2% and 11.4% over control devices, respectively. Electronic supplementary information (ESI) available: Details of the materials and instrumentation, device fabrication, measurement and calculations of the quantum yield (Qd), calculations of the Förster radius (R0), optimization of the ERDs mixed with electrolyte according to Type-A strategy; normalized absorption profiles of the N3, Ru505, and Z907 dyes and the emission profiles of DAPI and H33342

  5. The Molecular Control of Blood Cell Development

    NASA Astrophysics Data System (ADS)

    Sachs, Leo

    1987-12-01

    The establishment of a cell culture system for the clonal development of blood cells has made it possible to identify the proteins that regulate the growth and differentiation of different blood cell lineages and to discover the molecular basis of normal and abnormal cell development in blood forming tissues. A model system with myeloid blood cells has shown that (i) normal blood cells require different proteins to induce cell multiplication (growth inducers) and cell differentiation (differentiation inducers), (ii) there is a hierarchy of growth inducers as cells become more restricted in their developmental program, and (iii) a cascade of interactions between proteins determines the correct balance between immature and mature cells in normal blood cell development. Gene cloning has shown that there is a family of different genes for these proteins. Normal protein regulators of blood cell development can control the abnormal growth of certain types of leukemic cells and suppress malignancy by incuding differentiation to mature nondividing cells. Chromosome abnormalities that give rise to malignancy in these leukemic cells can be bypassed and their effects nullified by inducing differentiation, which stops cells from multiplying. These blood cell regulatory proteins are active in culture and in the body, and they can be used clinically to correct defects in blood cell development.

  6. Novel near-infrared carboxylated 1,3-indandione sensitizers for highly efficient flexible dye-sensitized solar cells.

    PubMed

    Shibayama, Naoyuki; Inoue, Yukiko; Abe, Masahiro; Kajiyama, Shingo; Ozawa, Hironobu; Miura, Hidetoshi; Arakawa, Hironori

    2015-08-18

    Three novel metal-free organic dyes (DN458, DN475 and DN484) were designed for use in plastic-substrate dye-sensitized solar cells (PDSCs). The photoelectric conversion region of DN475 was successfully expanded into the near-infrared region. As a result, an energy conversion efficiency of 5.76% was achieved.

  7. Novel near-infrared carboxylated 1,3-indandione sensitizers for highly efficient flexible dye-sensitized solar cells.

    PubMed

    Shibayama, Naoyuki; Inoue, Yukiko; Abe, Masahiro; Kajiyama, Shingo; Ozawa, Hironobu; Miura, Hidetoshi; Arakawa, Hironori

    2015-08-18

    Three novel metal-free organic dyes (DN458, DN475 and DN484) were designed for use in plastic-substrate dye-sensitized solar cells (PDSCs). The photoelectric conversion region of DN475 was successfully expanded into the near-infrared region. As a result, an energy conversion efficiency of 5.76% was achieved. PMID:26166712

  8. Lymph node cell proliferation assay in guinea pigs for the assessment of sensitizing potentials of chemical compounds.

    PubMed

    Kashima, R; Okada, J; Ikeda, Y

    1994-09-01

    The efficacy of a lymph node cell proliferation assay in the guinea pig as a first stage screening method of predicting sensitizing potentials of chemicals was studied by using several haptens. Animals were sensitized by a single 24-hr occlusive patch (24 cp), intradermal injection (id) and a combination of id and 24 cp, at a concentration used for guinea pig conventional contact hypersensitivity assay methods. Control animals were treated with vehicle(s) only. Suspensions of the lymph node cells (LNC) were individually prepared and cultured with [3H]methyl thymidine ([3H]TdR). [3H]TdR incorporation was measured and a stimulation index (SI) was calculated as a ratio of the mean [3H]TdR incorporation in sensitized animals and the mean [3H]TdR incorporation in control animals. LNC sensitized by 24 cp with 2,4-dinitrochlorobenzene proliferated maximally and significantly at day 5, whereas this occurred at day 7 after id sensitization. Significant LNC proliferation and high SI values were obtained successively by a combination of 24 cp and id. Moreover, strongly sensitizing chemicals increased significant LNC proliferation (SI > 2.0); weakly to moderately sensitizing chemicals also induced significant LNC proliferation (SI = 1.3-1.7). On the other hand, a primary irritant, sodium dodecyl sulfate, failed to encourage LNC proliferation (SI approximately 1.0).

  9. Fallopian tube secretory cell expansion: a sensitive biomarker for ovarian serous carcinogenesis

    PubMed Central

    Wang, Yiying; Li, Li; Wang, Yue; Tang, Sarah Ngocvi; Zheng, Wenxin

    2016-01-01

    Recent advances suggest that precancerous lesions of pelvic serous carcinoma originate from tubal secretory cells. The purpose of our study was to determine if an increased number of secretory cells vary with age or location in the fallopian tube and to examine its association with serous neoplasia. Three groups (benign control, high-risk, and pelvic serous carcinoma) of age-matched patients were studied. The age data were stratified into 10-year intervals ranging from 20-29 to older than 80. The number of secretory and ciliated cells from both tubal fimbria and ampulla segments was counted by microscopy and immunohistochemical staining methods. The data were analyzed by standard contingency table and Poisson distribution methods after age justification. We found that the absolute number of tubal secretory cells increased significantly with age in all three groups. But a more dramatic increase of secretory cells was observed in high-risk and pelvic serous carcinoma patients. Secretory cell expansion is more prevalent than secretory cell outgrowth in both fimbria and ampulla tubal segments and is significantly associated with serous neoplasia (p < 0.001). Furthermore, age remained a significant risk factor for serous neoplasia after age adjustment. These findings suggest that secretory cell expansion could serve as a potential sensitive biomarker for early serous carcinogenesis within the fallopian tube. The study also supports a relationship between serous neoplasia and increased secretory to ciliated cell ratios, and the relationship between frequency of secretory cell expansion within the fallopian tube and increasing age and-more significantly-presence of high-risk factors or co-existing serous cancers. PMID:27069556

  10. Co-sensitization of natural dyes for improved efficiency in dye-sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Kumar, K. Ashok; Subalakshmi, K.; Senthilselvan, J.

    2016-05-01

    In this paper, a new approach of co-sensitized DSSC based on natural dyes is investigated to explore the possible way to improve the power conversion efficiency. To realize this purpose 10 DSSC devices were fabricated using mono-sensitization and co-sensitization of ethanolic extracts of natural dye sensitizers obtained from Cactus fruit, Jambolana fruit, Curcumin and Bermuda grass. The optical absorption spectrum of the mono and hybrid dye extracts were studied by UV-Visible absorption spectrum. It shows the characteristic absorption peaks in visible region corresponds to the presence of natural pigments of anthocyanin, betacyanin and chlorophylls. Absorption spectrum of hybrid dyes reveals a wide absorption band in visible region with improved extinction co-efficient and it is favorable for increased light harvesting nature. The power conversion efficiency of DSSC devices were calculated using J-V curve and the maximum efficiency achieved in the present work is noted to be ~0.61% for Cactus-Bermuda co-sensitized DSSC.

  11. Comparisons of Robustness and Sensitivity between Cancer and Normal Cells by Microarray Data

    PubMed Central

    Chu, Liang-Hui; Chen, Bor-Sen

    2008-01-01

    Robustness is defined as the ability to uphold performance in face of perturbations and uncertainties, and sensitivity is a measure of the system deviations generated by perturbations to the system. While cancer appears as a robust but fragile system, few computational and quantitative evidences demonstrate robustness tradeoffs in cancer. Microarrays have been widely applied to decipher gene expression signatures in human cancer research, and quantification of global gene expression profiles facilitates precise prediction and modeling of cancer in systems biology. We provide several efficient computational methods based on system and control theory to compare robustness and sensitivity between cancer and normal cells by microarray data. Measurement of robustness and sensitivity by linear stochastic model is introduced in this study, which shows oscillations in feedback loops of p53 and demonstrates robustness tradeoffs that cancer is a robust system with some extreme fragilities. In addition, we measure sensitivity of gene expression to perturbations in other gene expression and kinetic parameters, discuss nonlinear effects in feedback loops of p53 and extend our method to robustness-based cancer drug design. PMID:19259409

  12. Mesenchymal Stem Cells Improve Heart Rate Variability and Baroreflex Sensitivity in Rats with Chronic Heart Failure

    PubMed Central

    de Morais, Sharon Del Bem Velloso; da Silva, Luiz Eduardo Virgilio; Lataro, Renata Maria; Silva, Carlos Alberto Aguiar; de Oliveira, Luciano Fonseca Lemos; de Carvalho, Eduardo Elias Vieira; Simões, Marcus Vinicius; da Silva Meirelles, Lindolfo; Fazan, Rubens

    2015-01-01

    Heart failure induced by myocardial infarct (MI) attenuates the heart rate variability (HRV) and baroreflex sensitivity, which are important risk factors for life-threatening cardiovascular events. Therapies with mesenchymal stem cells (MSCs) have shown promising results after MI. However, the effects of MSCs on hemodynamic (heart rate and arterial pressure) variability and baroreflex sensitivity in chronic heart failure (CHF) following MI have not been evaluated thus far. Male Wistar rats received MSCs or saline solution intravenously 1 week after ligation of the left coronary artery. Control (noninfarcted) rats were also evaluated. MI size was assessed using single-photon emission computed tomography (SPECT). The left ventricular ejection fraction (LVEF) was evaluated using radionuclide ventriculography. Four weeks after MSC injection, the animals were anesthetized and instrumented for chronic ECG recording and catheters were implanted in the femoral artery to record arterial pressure. Arterial pressure and HRVs were determined in time and frequency domain (spectral analysis) while HRV was also examined using nonlinear methods: DFA (detrended fluctuation analysis) and sample entropy. The initial MI size was the same among all infarcted rats but was reduced by MSCs. CHF rats exhibited increased myocardial interstitial collagen and sample entropy combined with the attenuation of the following cardiocirculatory parameters: DFA indices, LVEF, baroreflex sensitivity, and HRV. Nevertheless, MSCs hampered all these alterations, except the LVEF reduction. Therefore, 4 weeks after MSC therapy was applied to CHF rats, MI size and myocardial interstitial fibrosis decreased, while baroreflex sensitivity and HRV improved. PMID:26059001

  13. Functionalized graphene sheets in dye-sensitized solar cell counter electrodes

    NASA Astrophysics Data System (ADS)

    Roy-Mayhew, Joseph Dominic

    was achieved through better control of electrode morphology. By using ethyl cellulose as a sacrificial binder, and partially thermolyzing it, electrodes were created which exhibited lower effective charge transfer resistance (< 1 Ω·cm 2) than the traditional platinum electrodes for the iodide/triiodide, the cobalt bipyridine, and a sulfur-based redox couple. Dye-sensitized solar cells using these FGS electrodes had power conversion efficiencies equal to or greater than those using platinum nanoparticles with each of the three major redox mediators.

  14. Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes

    NASA Astrophysics Data System (ADS)

    Zhu, Hongwei; Zeng, Haifeng; Subramanian, Venkatachalam; Masarapu, Charan; Hung, Kai-Hsuan; Wei, Bingqing

    2008-11-01

    Carbon nanotube (CNT) films have been used as counter electrodes in natural dye-sensitized (anthocyanin-sensitized) solar cells to improve the cell performance. Compared with conventional cells using natural dye electrolytes and platinum as the counter electrodes, cells with a single-walled nanotube (SWNT) film counter electrode show comparable conversion efficiency, which is attributed to the increase in short circuit current density due to the high conductivity of the SWNT film.

  15. Bax overexpression enhances cytochrome c release from mitochondria and sensitizes KATOIII gastric cancer cells to chemotherapeutic agent-induced apoptosis.

    PubMed

    Sawa, H; Kobayashi, T; Mukai, K; Zhang, W; Shiku, H

    2000-04-01

    To evaluate whether overexpression of Bax, an apoptosis-promoting gene, sensitizes KATOIII gastric cancer cells to apoptosis induced by chemotherapeutic agents, three stable cell lines of KATOIII transfected with Bax (KATOIII-Bax), Bcl-2 (KATOIII-Bcl-2), or control pCI-neo expression vector (KATOIII-pCI-neo) were established. The cells were treated with paclitaxel, 5-fluorouracil, or doxorubicin, and the apoptotic response was measured. Our results showed that the sensitivity of the KATOIII-Bax cells to chemotherapeutic agents was enhanced compared with that of the KATOIII-pCI-neo cells, and the KATOIII-Bcl-2 cells were more resistant to these agents. Western blotting revealed that cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was higher than that of the KATOIII-pCI-neo cells. Significant increase of cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was detected 24 h after exposure to chemotherapeutic agents, when apoptotic cells were less than 10%. The cytochrome c level in the cytosol fraction of the KATOIII-Bax cells was higher than that of the KATOIII-pCI-neo cells at all time points examined after exposure to chemotherapeutic agents. Marked activation of caspase-3 in the KATOIII-Bax cells was observed 48 h and 72 h after exposure to chemotherapeutic agents compared with that in the KATOIII-pCI-neo cells. Consistently, zVAD-fmk, a pancaspase inhibitor, repressed the paclitaxel-induced apoptosis. In addition, Bcl-2 overexpression strongly blocked KATOIII cell apoptosis by inhibiting the cytochrome c release from mitochondria and caspase-3 activation. These findings suggest that cytochrome c release is a major mechanism of apoptotic response and Bax overexpression sensitizes KATOIII cells to chemotherapeutic agent-induced apoptosis through enhancing the release of cytochrome c from mitochondria. PMID:10717243

  16. Sensitive detection of cancer cells using light-mediated apta-PCR.

    PubMed

    Civit, Laia; Pinto, Alessandro; Rodrigues-Correia, Alexandre; Heckel, Alexander; O'Sullivan, Ciara K; Mayer, Günter

    2016-03-15

    Apta-PCR is an ultrasensitive assay in which aptamers are exploited not only as biomolecular recognition elements, but also as reporter labels for amplification via real-time PCR. This methodology has been successfully applied to the detection of proteins, achieving limits of detection in the picomolar range. The introduction of caged aptamers that bear photo-labile groups, so called cages, at strategic positions so that their tertiary structure and thus their binding properties can be controlled by light, facilitates a more robust and attractive assay in terms of sample conservation and reusability. In this work, we report for the first time the use of caged aptamers for cell detection in an apta-PCR assay. Specifically, a sandwich format is used combining the capture of B-cells by an antibody with the specific detection of Burkitt's lymphoma cancer cells by a caged aptamer, acting as a reporter probe. Elution of the aptamer bound to the cancer cells is performed by light and the number of cells is then correlated with the amount of eluted caged aptamer using real-time PCR analysis. The reported technique shows an excellent sensitivity, achieving detection of as few as 77 cells, and due to the inherent robustness of the assay, this detection platform can be reused for further analyses, demonstrating potential applicability in proteomics and clinical diagnostics.

  17. Clusterin knockdown sensitizes prostate cancer cells to taxane by modulating mitosis.

    PubMed

    Al Nakouzi, Nader; Wang, Chris Kedong; Beraldi, Eliana; Jager, Wolfgang; Ettinger, Susan; Fazli, Ladan; Nappi, Lucia; Bishop, Jennifer; Zhang, Fan; Chauchereau, Anne; Loriot, Yohann; Gleave, Martin

    2016-01-01

    Clusterin (CLU) is a stress-activated molecular chaperone that confers treatment resistance to taxanes when highly expressed. While CLU inhibition potentiates activity of taxanes and other anti-cancer therapies in preclinical models, progression to treatment-resistant disease still occurs implicating additional compensatory survival mechanisms. Taxanes are believed to selectively target cells in mitosis, a complex mechanism controlled in part by balancing antagonistic roles of Cdc25C and Wee1 in mitosis progression. Our data indicate that CLU silencing induces a constitutive activation of Cdc25C, which delays mitotic exit and hence sensitizes cancer cells to mitotic-targeting agents such as taxanes. Unchecked Cdc25C activation leads to mitotic catastrophe and cell death unless cells up-regulate protective mechanisms mediated through the cell cycle regulators Wee1 and Cdk1. In this study, we show that CLU silencing induces a constitutive activation of Cdc25C via the phosphatase PP2A leading to relief of negative feedback inhibition and activation of Wee1-Cdk1 to promote survival and limit therapeutic efficacy. Simultaneous inhibition of CLU-regulated cell cycle effector Wee1 may improve synergistic responses of biologically rational combinatorial regimens using taxanes and CLU inhibitors. PMID:27198502

  18. Sensitive detection of cancer cells using light-mediated apta-PCR.

    PubMed

    Civit, Laia; Pinto, Alessandro; Rodrigues-Correia, Alexandre; Heckel, Alexander; O'Sullivan, Ciara K; Mayer, Günter

    2016-03-15

    Apta-PCR is an ultrasensitive assay in which aptamers are exploited not only as biomolecular recognition elements, but also as reporter labels for amplification via real-time PCR. This methodology has been successfully applied to the detection of proteins, achieving limits of detection in the picomolar range. The introduction of caged aptamers that bear photo-labile groups, so called cages, at strategic positions so that their tertiary structure and thus their binding properties can be controlled by light, facilitates a more robust and attractive assay in terms of sample conservation and reusability. In this work, we report for the first time the use of caged aptamers for cell detection in an apta-PCR assay. Specifically, a sandwich format is used combining the capture of B-cells by an antibody with the specific detection of Burkitt's lymphoma cancer cells by a caged aptamer, acting as a reporter probe. Elution of the aptamer bound to the cancer cells is performed by light and the number of cells is then correlated with the amount of eluted caged aptamer using real-time PCR analysis. The reported technique shows an excellent sensitivity, achieving detection of as few as 77 cells, and due to the inherent robustness of the assay, this detection platform can be reused for further analyses, demonstrating potential applicability in proteomics and clinical diagnostics. PMID:26615953

  19. Fuel cell stack monitoring and system control

    DOEpatents

    Keskula, Donald H.; Doan, Tien M.; Clingerman, Bruce J.

    2004-02-17

    A control method for monitoring a fuel cell stack in a fuel cell system in which the actual voltage and actual current from the fuel cell stack are monitored. A preestablished relationship between voltage and current over the operating range of the fuel cell is established. A variance value between the actual measured voltage and the expected voltage magnitude for a given actual measured current is calculated and compared with a predetermined allowable variance. An output is generated if the calculated variance value exceeds the predetermined variance. The predetermined voltage-current for the fuel cell is symbolized as a polarization curve at given operating conditions of the fuel cell.

  20. Risk-Sensitive Control of Pure Jump Process on Countable Space with Near Monotone Cost

    SciTech Connect

    Suresh Kumar, K. Pal, Chandan

    2013-12-15

    In this article, we study risk-sensitive control problem with controlled continuous time pure jump process on a countable space as state dynamics. We prove multiplicative dynamic programming principle, elliptic and parabolic Harnack’s inequalities. Using the multiplicative dynamic programing principle and the Harnack’s inequalities, we prove the existence and a characterization of optimal risk-sensitive control under the near monotone condition.

  1. The effects of various salt and sucrose solutions on the U.V.L. sensitivity of CHO cells.

    PubMed

    Romano, S L; Raaphorst, G P; Dewey, W C

    1979-05-01

    The response of cultured CHO cells to U.V.L. irradiation during treatment with anisotonic solutions shows that treatment with hypotonic sucrose, NaCl or KCl solutions causes an increase in the cellular U.V.L. sensitivity, while exposure to hypertonic solutions causes a large decrease in U.V.L. sensitivity. Cells exposed to 1.8 M sucrose, NaCl or KCl solutions and given a U.V.L. dose of 252 erg/mm2 towards the end of the 20 min solution exposure time have survival levels which are respectively 228,26, and 23 times higher than the controls, i.e. cells irradiated in phosphate buffered saline. Cell volume data obtained using a Coulter counter, and nuclear area data of attached cells obtained using an optical microscope with a micrometer reticle, show that cell and nuclear size are related to U.V.L. sensitivity. That is, as cells shrink and the nuclear area decreases, the cells become more U.V.L.-resistant. During hypotonic treatment with 0.1 M NaCl, the cell volume, nuclear area and U.V.L. sensitivity increased in the first 2 to 4 min of exposure time, but at longer exposure times (greater than 3 to 4 min), cell volume, nuclear area and cellular U.V.L. sensitivity decreased. For 0.1 M KCl treatment the cells initially displayed a rapid increase in volume, nuclear area and U.V.L. sensitivity, but at the longer exposure times no decrease in cell and nuclear size were observed, and a slight increase in U.V.L. sensitivity occurred. Changes in U.V.L. sensitivity were related to changes in nuclear size and cell volume; however, calculations showed that during hypertonic treatment there is an ionic effect as well as an osmotic effect. That is, the cellular U.V.L. survival in equal hypertonic concentrations of NaCl or KCl was lower than in the same concentration of sucrose. PMID:313917

  2. Mechanisms of daughter cell-size control during cell division.

    PubMed

    Kiyomitsu, Tomomi

    2015-05-01

    Daughter cell size is tightly regulated during cell division. In animal cells, the position of the anaphase spindle specifies the cell cleavage site to dictate the relative size of the daughter cells. Although spindle orientation is regulated by dynein-dependent cortical pulling forces exerted on astral microtubules in many cell types, it was unclear how these forces are precisely regulated to center or displace the spindle. Recently, intrinsic signals derived from chromosomes or spindle poles have been demonstrated to regulate dynein-dependent pulling forces in symmetrically dividing cells. Unexpectedly, myosin-dependent contractile forces have also been shown to control spindle position by altering the cellular boundaries during anaphase. In this review, I discuss how dynein- and myosin-dependent forces are coordinately regulated to control daughter cell size. PMID:25548067

  3. Metal oxide-encapsulated dye-sensitized photoanodes for dye-sensitized solar cells

    DOEpatents

    Hupp, Joseph T.; Son, Ho-Jin

    2016-01-12

    Dye-sensitized semiconducting metal oxide films for photoanodes, photoanodes incorporating the films and DSCs incorporating the photoanodes are provided. Also provided are methods for making the dye sensitized semiconducting metal oxide films. The methods of making the films are based on the deposition of an encapsulating layer of a semiconducting metal oxide around the molecular anchoring groups of photosensitizing dye molecules adsorbed to a porous film of the semiconducting metal oxide. The encapsulating layer of semiconducting metal oxide is formed in such a way that it is not coated over the chromophores of the adsorbed dye molecules and, therefore, allows the dye molecules to remain electrochemically addressable.

  4. [CD11b-positive cells expression in rectal mucosa from ovalbumin sensitized and challenged rabbits].

    PubMed

    Bassan, Norberto; Vinuesa, Miguel; Roma, Stella

    2005-01-01

    Rabbit MAC-1 receptor, homologue to human CD11b is present in macrophages. The aim of the study was to determine quantitative and distributive modifications of CD11b-positive cells that participate in immune response at rectal mucosa, in an animal model of mucosal immunity. New Zealand rabbits were divided into three groups. G1: control; G2: ovalbumin (OVA) sensitized; G3: OVA-senstitized and rectal challenged. Animals were subcutaneously sensitized twice with 70 microg OVA and 30 ml aluminium hydroxide in 2 ml saline solution. Rectal challenge was developed with a solution of 50 mg OVA in 5 ml saline solution. Sensitized groups (G2 and G3) showed a positive PCA (Passive Cutaneous Anaphylaxis) at 1/160 fold dilutions. In G3 we observed a patchy mucosal edema, lymphangiectasis and eosinophil leucocyte infiltration. Cells were counted as the number of cells per high power field. G1: 9.64 (SE 0.22); G2: 18.10 (SE 0.09) and G3: 23.60 (SE 0.29). (G2 vs G1 p < 0.001; G3 vs G1 p < 0.001; G3 vs G2 p < 0.001). We conclude that there is a close relationship between the food antigen OVA penetration (after challenge) and the increase of CD11b positive cells in rectal mucosa. This fact could be due to the cellular influx to the inflammatory site by the action of chemotactic factors released after challenge.

  5. Sensitivity and mechanisms of taxol-resistant prostate adenocarcinoma cells to Vernonia amygdalina extract.

    PubMed

    Cameron, Keyuna S; Howard, Carolyn B; Izevbigie, Ernest B; Hill, Brandon J; Tchounwou, Paul B

    2013-09-01

    Prostate cancer (PC) patients once Paclitaxel (TAX) treatment responsive later develop hormone refractory PC, thus becoming TAX-insensitive. This underscores the urgent need to develop novel anti-PC therapies. Vernonia amygdalina (VA) could be one such candidate agent. We have shown that androgen-independent PC-3 cells are sensitive to VA treatment in vitro. VA extract (0.01, 0.1 and 1 mg/ml) inhibited DNA synthesis by 12%, 45% (p<0.05), and 73% (p<0.01) respectively. In contrast, TAX (0.01, 0.1, and 1 μM) failed to significantly affect cell growth, suggesting TAX resistance. We tested molecular mechanisms which may lend to the observed PC-3 cell VA sensitivity/TAX resistance. Though both VA and TAX stimulated MAPK activity, VA's induction was more intense, but transient, compared to TAX's sustained action. NF-κB activation was inhibited on average by 50% by either 1 mg/ml VA or 1 μM TAX. VA extract caused 35% and 45% increases in c-Myc activity at 10 and 60 min intervals respectively, with the highest stimulation attained 1h after treatment. In contrast, similar levels were attained by TAX rapidly (within 5 min) and were sustained compared to the slow/multi-phasic action of VA. VA extract treatments had no effect on AKT gene expression, while TAX treatments yielded a four-fold (P<0.01) increase; and P-glycoprotein (P-gp) activity was inhibited by VA and stimulated by TAX, compared to control (basal ATPase activity). This study shows that TAX-resistant PC-3 cells are sensitive to VA, perhaps explained by differential regulatory patterns of MAPK, c-Myc, AKT, and Pgp activities/expressions. PMID:23238229

  6. Inhibition of geranylgeranylation mediates sensitivity to CHOP-induced cell death of DLBCL cell lines

    SciTech Connect

    Ageberg, Malin; Rydstroem, Karin; Linden, Ola; Linderoth, Johan; Jerkeman, Mats; Drott, Kristina

    2011-05-01

    Prenylation is a post-translational hydrophobic modification of proteins, important for their membrane localization and biological function. The use of inhibitors of prenylation has proven to be a useful tool in the activation of apoptotic pathways in tumor cell lines. Rab geranylgeranyl transferase (Rab GGT) is responsible for the prenylation of the Rab family. Overexpression of Rab GGTbeta has been identified in CHOP refractory diffuse large B cell lymphoma (DLBCL). Using a cell line-based model for CHOP resistant DLBCL, we show that treatment with simvastatin, which inhibits protein farnesylation and geranylgeranylation, sensitizes DLBCL cells to cytotoxic treatment. Treatment with the farnesyl transferase inhibitor FTI-277 or the geranylgeranyl transferase I inhibitor GGTI-298 indicates that the reduction in cell viability was restricted to inhibition of geranylgeranylation. In addition, treatment with BMS1, a combined inhibitor of farnesyl transferase and Rab GGT, resulted in a high cytostatic effect in WSU-NHL cells, demonstrated by reduced cell viability and decreased proliferation. Co-treatment of BMS1 or GGTI-298 with CHOP showed synergistic effects with regard to markers of apoptosis. We propose that inhibition of protein geranylgeranylation together with conventional cytostatic therapy is a potential novel strategy for treating patients with CHOP refractory DLBCL.

  7. Progressive sharing of multiple images with sensitivity-controlled decoding

    NASA Astrophysics Data System (ADS)

    Chang, Sheng-Yu; Lee, Suiang-Shyan; Yeh, Tzu-Min; Chen, Lee Shu-Teng; Lin, Ja-Chen

    2015-12-01

    Secure sharing of digital images is becoming an important issue. Consequently, many schemes for ensuring image sharing security have been proposed. However, existing approaches focus on the sharing of a single image, rather than multiple images. We propose three kinds of sharing methods that progressively reveal n given secret images according to the sensitivity level of each image. Method 1 divides each secret image into n parts and then combines and hides the parts of the images to get n steganographic (stego) JPEG codes of equal importance. Method 2 is similar; however, it allocates different stego JPEG codes of different `weights' to indicate their strength. Method 3 first applies traditional threshold-sharing to the n secret images, then progressively shares k keys, and finally combines the two sharing results to get n stego JPEG codes. In the recovery phase, various parameters are compared to a pre-specified low/middle/high (L/M/H) threshold and, according to the respective method, determine whether or not secret images are reconstructed and the quality of the images reconstructed. The results of experiments conducted verify the efficacy of our methods.

  8. Single Cell Adhesion Assay Using Computer Controlled Micropipette

    PubMed Central

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today’s techniques typically have an extremely low throughput (5–10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub

  9. Single cell adhesion assay using computer controlled micropipette.

    PubMed

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today's techniques typically have an extremely low throughput (5-10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub-population of

  10. The Spectral Sensitivities of Single Cells in the Median Ocellus of Limulus

    PubMed Central

    Nolte, John; Brown, Joel E.

    1969-01-01

    The spectral sensitivities of single Limulus median ocellus photoreceptors have been determined from records of receptor potentials obtained using intracellular microelectrodes. One class of receptors, called UV cells (ultraviolet cells), depolarizes to near-UV light and is maximally sensitive at 360 nm; a Dartnall template fits the spectral sensitivity curve. A second class of receptors, called visible cells, depolarizes to visible light; the spectral sensitivity curve is fit by a Dartnall template with λmax at 530 nm. Dark-adapted UV cells are about 2 log units more sensitive than dark-adapted visible cells. UV cells respond with a small hyperpolarization to visible light and the spectral sensitivity curve for this hyperpolarization peaks at 525–550 nm. Visible cells respond with a small hyperpolarization to UV light, and the spectral sensitivity curve for this response peaks at 350–375 nm. Rarely, a double-peaked (360 and 530 nm) spectral sensitivity curve is obtained; two photopigments are involved, as revealed by chromatic adaptation experiments. Thus there may be a small third class of receptor cells containing two photopigments. PMID:5346532

  11. Lithium-Ion Cell Charge Control Unit

    NASA Technical Reports Server (NTRS)

    Reid, Concha; Button, Robert; Manzo, Michelle; McKissock, Barbara; Miller, Thomas; Gemeiner, Russel; Bennett, William; Hand, Evan

    2006-01-01

    Life-test data of Lithium-Ion battery cells is critical in order to establish their performance capabilities for NASA missions and Exploration goals. Lithium-ion cells have the potential to replace rechargeable alkaline cells in aerospace applications, but they require a more complex charging scheme than is typically required for alkaline cells. To address these requirements in our Lithium-Ion Cell Test Verification Program, a Lithium-Ion Cell Charge Control Unit was developed by NASA Glenn Research Center (GRC). This unit gives researchers the ability to test cells together as a pack, while allowing each cell to charge individually. This allows the inherent cell-to-cell variations to be addressed on a series string of cells and results in a substantial reduction in test costs as compared to individual cell testing. The Naval Surface Warfare Center at Crane, Indiana developed a power reduction scheme that works in conjunction with the Lithium-Ion Cell Charge Control Unit. This scheme minimizes the power dissipation required by the circuitry to prolong circuit life and improve its reliability.

  12. Nerve growth factor-sensitive S6 kinase in cell-free extracts from PC12 cells

    SciTech Connect

    Matsuda, Y.; Nakanishi, N.; Dickens, G.; Guroff, G.

    1986-05-01

    Soluble extracts from nerve growth factor (NGF)-stimulated PC12 cells prepared by alkaline lysis show a 2-10 fold increase in the ability to phosphorylate the ribosomal protein S6. The alkaline lysis method yields a preparation of much higher specific activity than does sonication. Half-maximal incorporation of (/sup 32/P) from (/sup 32/P)ATP into S6 occurred after 4-7 minutes of nerve growth factor treatment. The partially purified NGF-sensitive S6 kinase has a molecular weight of 45,000 and is not inhibited by the inhibitor of cAMP-dependent protein kinase, NaCl, or trifluoperazine, nor is it activated by the addition of diolein plus phosphatidylserine. Trypsin treatment of either crude extracts or partially purified S6 kinase from control or NGF-treated cells was without effect. These data suggest that the S6 kinase stimulated by NGF is neither cAMP-dependent protein kinase, protein kinase C, nor the result of proteolytic activation of an inactive proenzyme. Treatment of intact cells with dibutyryl cyclic AMP or 5'-N-ethylcarboxamideadenosine also increases the subsequent cell-free phosphorylation of S6. But the effect of NGF in increasing S6 kinase activity cannot be mimicked by treatment of control extract with cAMP-dependent protein kinase in vitro. Thus, it is unlikely to result from the phosphorylation of a less active form of the S6 kinase by a cAMP-dependent protein kinase.

  13. Control points within the cell cycle

    SciTech Connect

    Van't Hof, J.

    1984-01-01

    Evidence of the temporal order of chromosomal DNA replication argues favorably for the view that the cell cycle is controlled by genes acting in sequence whose time of expression is determined by mitosis and the amount of nuclear DNA (2C vs 4C) in the cell. Gl and G2 appear to be carbohydrate dependent in that cells starved of either carbohydrate of phosphate fail to make these transitions. Cells deprived of nitrate, however, fail only at Gl to S transition indicating that the controls that operate in G1 differ from those that operate in G2. 46 references, 5 figures.

  14. Peripheral Hole Acceptor Moieties on an Organic Dye Improve Dye‐Sensitized Solar Cell Performance

    PubMed Central

    Hao, Yan; Gabrielsson, Erik; Lohse, Peter William; Yang, Wenxing; Johansson, Erik M. J.; Hagfeldt, Anders

    2015-01-01

    Investigation of charge transfer dynamics in dye‐sensitized solar cells is of fundamental interest and the control of these dynamics is a key factor for developing more efficient solar cell devices. One possibility for attenuating losses through recombination between injected electrons and oxidized dye molecules is to move the positive charge further away from the metal oxide surface. For this purpose, a metal‐free dye named E6 is developed, in which the chromophore core is tethered to two external triphenylamine (TPA) units. After photoinduced electron injection into TiO2, the remaining hole is rapidly transferred to a peripheral TPA unit. Electron–hole recombination is slowed down by 30% compared to a reference dye without peripheral TPA units. Furthermore, it is found that the added TPA moieties improve the electron blocking effect of the dye, retarding recombination of electrons from TiO2 to the cobalt‐based electrolyte. PMID:27722076

  15. Conformal growth of anodic nanotubes for dye-sensitized solar cells: part II. Nonplanar electrode.

    PubMed

    Sun, Lidong; Zhang, Sam; Wang, Qing

    2014-02-01

    Anodic titania nanotube array features highly ordered alignment as well as porous nature, and exhibits intriguing properties when employed in a variety of applications. All these profit from the continuous efforts on controlling the nanotube configurations. Recently, nonplanar electrodes have also been used to grow the nanotubes besides the conventional planar counterparts. As such, it is of great interest and significance to complete a picture to link the nanotubes grown on planar and various nonplanar electrodes for a comprehensive understanding of nanotube growing manners, in an attempt to boost their future applications. In the first part of this review, planar electrodes are focused with regard to nanotube growth and application in dye-sensitized solar cells. In this part, the nanotubes grown on patterned or curved surfaces are discussed first with reference to a similar structure of alumina nanopores, which are subsequently used to mirror the growth of nanotubes on cylindrical electrodes (i.e., titanium wires or meshes). The last section focuses on titanium tubular electrodes which are attractive for thermal fluids in view of the drastically reduced thermal conductivity in the presence of anodic nanotubes. As a recent hot topic, wire-shaped dye-sensitized solar cells are deliberated in terms of cell structure, efficiency calculation, merits, challenges and outlook.

  16. The Effect of Iron Deficiency on Osmotic Sensitivity of Red Blood Cells from Neonatal Rats and Their Mothers.

    PubMed

    Al-Hashimi, L Mossa; Gambling, Lorraine; McArdle, H J

    2015-12-01

    Iron deficiency during pregnancy has many effects on both the mother and her developing foetus. These can be both short and long term. One effect is an alteration in fatty acid metabolism and we hypothesised that these changes may result in alterations in membrane function and structure. In order to test this hypothesis, we measured osmotic sensitivity in red blood cells isolated from neonates and their mothers at different times following birth. We fed female rats control or iron-deficient diets for 4 weeks prior to mating and kept them on the same diet until term. At that time, we returned one group of deficient dams to the control diet. The others were kept on the same diet. We showed that iron deficiency results in a decrease in osmotic sensitivity in the mothers but not in their neonates. Returning the dams to the control diet resulted in a return of their red cell osmotic sensitivity to control levels. In the neonates, there was no recovery in haematocrit or in any other parameter, though they did not get any worse, in contrast to the pups being suckled by deficient mothers. The data show two things. The first is that following birth, the mother restores her own iron stores at the expense of the pups, and secondly, there are differences in properties and sensitivities between red cells from mothers and their neonates. This latter observation cannot be explained by differences in the membrane fatty acid profiles, which were not significantly different.

  17. Transforming potential and matrix stiffness co-regulate confinement sensitivity of tumor cell migration

    PubMed Central

    Pathak, Amit

    2013-01-01

    It is now well established that tumor cell invasion through tissue is strongly regulated by the microstructural and mechanical properties of the extracellular matrix (ECM). However, it remains unclear how these physical microenvironmental inputs are jointly processed with oncogenic lesions to drive invasion. In this study, we address this open question by combining a microfabricated polyacrylamide channel (μPAC) platform that enables independent control of ECM stiffness and confinement with an isogenically-matched breast tumor progression series in which the oncogenes ErbB2 and 14-3-3ζ are overexpressed independently or in tandem. We find that increasing channel confinement and overexpressing ErbB2 both promote cell migration to a similar degree when other parameters are kept constant. In contrast, 14-3-3ζ overexpression slows migration speed, and does so in a fashion that dwarfs effects of ECM confinement and stiffness. We also find that ECM stiffness dramatically enhances cell motility when combined with ErbB2 overexpression, demonstrating that biophysical cues and cell-intrinsic parameters promote cell invasion in an integrative manner. Morphometric analysis of cells inside the μPAC platform reveals that the rapid cell migration induced by narrow channels and ErbB2 overexpression both are accompanied by increased cell polarization. Disruption of this polarization by pharmacological inhibition of Rac GTPase phenocopies 14-3-3ζ overexpression by reducing cell polarization and slowing migration. By systematically measuring migration speed as a function of matrix stiffness and confinement, we also quantify for the first time the sensitivity of migration speed to microchannel properties and transforming potential. These results demonstrate that oncogenic lesions and ECM biophysical properties can synergistically interact to drive invasive migration, and that both inputs may act through common molecular mechanisms to enhance migration speed. PMID:23832051

  18. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    SciTech Connect

    Singh, Neetu Kapoor, Avinashi; Kumar, Vinod; Mehra, R. M.

    2014-04-24

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  19. Advanced Cd(II) complexes as high efficiency co-sensitizers for enhanced dye-sensitized solar cell performance.

    PubMed

    Gao, Song; Fan, Rui Qing; Wang, Xin Ming; Qiang, Liang Sheng; Wei, Li Guo; Wang, Ping; Yang, Yu Lin; Wang, Yu Lei

    2015-11-01

    This work reports on two new complexes with the general formula [Cd3(IBA)3(Cl)2(HCOO)(H2O)]n (1) and {[Cd1.5(IBA)3(H2O)6]·3.5H2O}n (2), which can be synthesized by the reaction of Cd(II) with rigid linear ligand 4-HIBA containing imidazolyl and carboxylate functional groups [4-HIBA = 4-(1H-imidazol-1-yl)benzoic acid]. Single-crystal X-ray diffraction analyses indicate that complex 1 is a 2D "wave-like" layer structure constructed from trinuclear units and complex 2 is just a mononuclear structure. Surprisingly, both complexes 1 and 2 appear as a 3D supramolecular network via intermolecular hydrogen bonding interactions. What's more, due to their strong UV-visible absorption, 1 and 2 can be employed as co-sensitizers in combination with N719 to enhance dye-sensitized solar cell (DSSC) performance. Both of them could overcome the deficiency of the ruthenium complex N719 absorption in the region of ultraviolet and blue-violet, and the charge collection efficiency is also improved when 1 and 2 are used as co-sensitizers, which are all in favor of enhancing the performance. The DSSC devices using co-sensitizers of 1/N719 and 2/N719 show an overall conversion efficiency of 8.27% and 7.73% with a short circuit current density of 17.48 mA cm(-2) and 17.39 mA cm(-2), and an open circuit voltage of 0.75 V and 0.74 V, respectively. The overall conversion efficiency is 27.23% and 18.92% higher than that of a device solely sensitized by N719 (6.50%). Consequently, the prepared complexes are high efficiency co-sensitizers for enhancing the performance of N719 sensitized solar cells. PMID:26419745

  20. In situ monitoring and optimization of room temperature ultra-fast sensitization for dye-sensitized solar cells.

    PubMed

    Davies, Matthew L; Watson, Trystan M; Holliman, Peter J; Connell, Arthur; Worsley, David A

    2014-10-25

    We describe the fastest dyeing of TiO2 photo-electrodes for dye-sensitized solar cells reported to date (<2 min) at room temperature giving η = 7.5% for an N719-SQ1-CDCA mixture which is significantly higher than devices dyed for >12 h using the same dye mixture (η = 5.5%). Time-lapse photography has been used to monitor the ultra-fast co-sensitization. The data show significantly different dye uptake between passive and pump dyeing reflecting competitive sorption between a Ru complex (N719) and an organic dye (SQ1).

  1. β-Cell Sensitivity to GLP-1 in Healthy Humans Is Variable and Proportional to Insulin Sensitivity

    PubMed Central

    Aulinger, Benedikt A.; Vahl, Torsten P.; Wilson-Pérez, Hilary E.; Prigeon, Ron L.

    2015-01-01

    Context: Glucagon-like peptide-1 (GLP-1) is an insulinotropic factor made in the gastrointestinal tract that is essential for normal glucose tolerance. Infusion of GLP-1 increases insulin secretion in both diabetic and nondiabetic humans. However, the degree to which people vary in their β-cell sensitivity to GLP-1 and the factors contributing to this variability have not been reported. Objective: The objective was to measure the sensitivity of insulin secretion to GLP-1 in cohorts of lean and obese subjects across a broad range of insulin sensitivity. Methods: Insulin secretion was measured during clamped hyperglycemia (7.2 mmol/L) and graded GLP-1 infusion in young, healthy subjects, and GLP-1 sensitivity was computed from the insulin secretion rate (ISR) during progressive increases in plasma GLP-1. Results: All subjects had fasting glucose values <5.2 mm. The obese subjects were insulin resistant compared to the lean group (homeostasis model of assessment 2 for insulin resistance: obese, 2.6 ± 0.5; lean, 0.8 ± 0.1; P < .001). ISR increased linearly in both cohorts with escalating doses of GLP-1, but the slope of ISR in response to GLP-1 was greater in the obese than in the lean subjects (obese, 0.17 ± 0.03 nmol/min/pm; lean, 0.05 ± 0.01 nmol/min/pm; P < .001). There was a significant association of β-cell GLP-1 sensitivity and insulin resistance (r = 0.83; P < .001), and after correction for homeostasis model of assessment 2 for insulin resistance, the slopes of ISR vs GLP-1 concentration did not differ in the two cohorts (obese, 0.08 ± 0.01; lean, 0.08 ± 0.01; P = .98). However, within the entire study group, β-cell GLP-1 sensitivity corrected for insulin resistance varied nearly 10-fold. Conclusions: Insulin secretion in response to GLP-1 is proportional to insulin resistance in healthy subjects. However, there is considerable variability in the sensitivity of the β-cell to GLP-1 that is independent of insulin sensitivity. PMID:25825945

  2. Plasmon-controlled fluorescence towards high-sensitivity optical sensing.

    PubMed

    Ray, K; Chowdhury, M H; Zhang, J; Fu, Y; Szmacinski, H; Nowaczyk, K; Lakowicz, J R

    2009-01-01

    Fluorescence spectroscopy is widely used in chemical and biological research. Until recently most of the fluorescence experiments have been performed in the far-field regime. By far-field we imply at least several wavelengths from the fluorescent probe molecule. In recent years there has been growing interest in the interactions of fluorophores with metallic surfaces or particles. Near-field interactions are those occurring within a wavelength distance of an excited fluorophore. The spectral properties of fluorophores can dramatically be altered by near-field interactions with the electron clouds present in metals. These interactions modify the emission in ways not seen in classical fluorescence experiments. Fluorophores in the excited state can create plasmons that radiate into the far-field and fluorophores in the ground state can interact with and be excited by surface plasmons. These reciprocal interactions suggest that the novel optical absorption and scattering properties of metallic nanostructures can be used to control the decay rates, location, and direction of fluorophore emission. We refer to these phenomena as plasmon-controlled fluorescence (PCF). An overview of the recent work on metal-fluorophore interactions is presented. Recent research combining plasmonics and fluorescence suggest that PCF could lead to new classes of experimental procedures, novel probes, bioassays, and devices.

  3. Control of IgE responses. II. Isotype specific suppression of peak hapten specific IgE antibody forming cell responses in BPO-KLH sensitized mice after oral administration of muramyldipeptide or murabutide.

    PubMed

    Auci, D L; Chice, S M; Dukor, P; Durkin, H G

    1993-01-01

    Muramyldipeptide (MDP) and murabutide (MB), a pyrogen free derivative of MDP, suppressed BPO specific IgE antibody forming cell (AFC) responses in vivo. To induce IgE responses, BALB/c mice were injected intraperitoneally (i.p.) with BPO-KLH (10 micrograms) in alum on days 0 and 21, or on days 0, 21 and 42. On day 44, mice were fed (gavage) or injected subcutaneously (s.c.) with MDP or MB (0.1-500 mg/kg). Mice were killed on days 45-70, and the numbers of BPO specific IgM, IgG1, IgE, and IgA antibody forming cells (AFC) in lymphoid organs determined in ELISPOT assay. With either immunization schedule, oral treatment with MDP or MB on day 44 suppressed BPO specific IgE AFC responses within 48 h (65-100%). With both molecules, the suppression was IgE isotype specific, dose dependent and transient. The suppression was also route specific since it was obtained only when MDP or MB was given by gavage, and not when injected s.c. These results show that peak antigen specific IgE responses can be suppressed in vivo, in isotype specific fashion, by a clearly defined class of molecules, one of which, MB, is a candidate for clinical studies in man. Pharmacologic agents of this type may be suitable for use in the therapeutic or prophylactic suppression of IgE and, hence, in the therapy of IgE mediated diseases such as allergic rhinitis, asthma, and other atopic diseases.

  4. Differential sensitivity of normal and malignant breast epithelial cells to genistein is partly mediated by p21(WAF1).

    PubMed

    Upadhyay, S; Neburi, M; Chinni, S R; Alhasan, S; Miller, F; Sarkar, F H

    2001-06-01

    Genistein, a soy metabolite, is a potential chemopreventive agent against various types of cancer. There are several studies documenting molecular alterations leading to cell cycle arrest and induction of apoptosis in a variety of cancer cells; however, no studies, to date, have shown the effect of genistein in isogenic normal and malignant breast epithelial cells. In this study, we investigated whether genistein shows any differential sensitivity to normal (MCF10A and MCF12A) and malignant (MCF10CA1a and MDA-MB-231) breast epithelial cells. We found that genistein causes a greater degree of G(2)-M arrest and induces apoptosis in malignant cell lines compared with normal breast epithelial cells. After genistein treatment, flow cytometric analysis revealed a hyperdiploid population in malignant cells that was not observed in normal cells. Cell cycle regulator p21(WAF1), which is known to be up-regulated by genistein treatment, was greatly induced at RNA and protein levels in normal cells, whereas its level was only slightly induced in malignant MDA-MB-231 cells and not detectable in malignant MCF10CA1a cells. Therefore, we investigated the causal role of p21(WAF1) in the differential sensitivity of genistein among these cell lines. We examined the effects of genistein on p21(WAF1) -/- and p21(WAF1) +/+ HCT116 cells, which were used as controls prior to studies on breast cancer cells. We found that there was a greater degree of cell cycle arrest and apoptosis in p21(WAF1) -/- cells compared with p21(WAF1) +/+ HCT116 cells after genistein treatment. Flow cytometric analysis after genistein treatment showed a significant number of p21(WAF1) -/- cells in the hyperdiploid population, which are probably programmed to die through apoptotic processes. To further confirm the causal role of p21(WAF1) in genistein-mediated cell cycle arrest and apoptosis, we down-regulated p21(WAF1) by antisense p21(WAF1) cDNA transfection experiments. We found that both normal and malignant p

  5. Dentine sensitivity risk factors: A case–control study

    PubMed Central

    Mafla, Ana Cristina; Lopez-Moncayo, Luis Fernando

    2016-01-01

    Objective: To identify the clinical and psychological risk factors associated with dentine hypersensitivity (DH) in order to provide an early diagnosis and preventive therapy. Materials and Methods: A nested case–control study was design between 2011 and 2012. A total of 61 DH cases and 122 controls participated in this investigation. Cases and controls were matched for sex, group of age and socioeconomic status in a ratio of 1:2. DH to different stimuli such as cold, heat, acid, and sweet was asked in patient interviews, and dental examinations were used to detect DH. Clinical and psychological risk factors such as dental hygiene, periodontal disease, acid diet, alcohol consumption, psychological stress, and psychopathological symptoms were inquired. Psychological stress was measured through the PSS-10 and psychopathological symptoms were evaluated by SCL-90-R in Spanish. Descriptive and univariate binary logistic regression analysis were performed to estimate the association between clinical and psychological risk factors and the presence of DH. Results: Toothpaste abrasivity (odds ratio [OR] 1.881, 95% confidence interval [CI] 1.010–3.502, P = 0.045), gingival recession (OR 2.196, 95% CI 1.020–4.728, P = 0.041), and periodontal therapy (OR 5.357, 95% CI 2.051–13.993, P < 0.001) were associated with DH. Subjects with perceived stress (OR 1.211, 95%, CI 0.518–2.833, P = 0.658), obsessive-compulsive (OR 1.266, 95%, CI 0.494–3.240, P = 0.623) and hostility (OR 1.235, 95%, CI 0.507–3.007, P = 0.642) symptoms had a clinical greater odd of DH. Conclusion: Oral hygiene products and periodontal conditions are important risk factors for DH. Individuals with perceived stress, obsessive-compulsive, and hostility symptoms may increase a clinical risk for this entity. Targeting to dental counseling focused on oral hygiene products, periodontal therapy and a psychological evaluation may be promising in DH prevention. PMID:27011732

  6. New triarylamine sensitizers for high efficiency dye-sensitized solar cells: Recombination kinetics of cobalt(III) complexes at titania/dye interface

    NASA Astrophysics Data System (ADS)

    Gao, Weixue; Liang, Mao; Tan, Yulin; Wang, Min; Sun, Zhe; Xue, Song

    2015-06-01

    A new generation of dye-sensitized solar cells (DSCs) is based on a combination of D-π-A organic dyes in conjunction with cobalt-based redox mediators. Here, two new triarylamine organic dyes (M36 and M37) toward cobalt electrolytes are constructed and employed as photosensitizers for dye-sensitized solar cells. The photoelectrochemical properties and photovoltaic performance of dyes are sensitive to the slightly structural modification of the terminal donor in triarylamine. Recombination kinetics of cobalt(III) complexes at titania/dye interface are also studied using electrochemical impedance spectroscopy and controlled intensity modulated photovoltage spectroscopy measurements. Our results show that, for M36 sensitized DSCs, a Marcus inverted region can be reached for the charge recombination kinetics behavior of cobalt(III) species. While that for DSCs based on M37 just lies in the Marcus normal region. The results can be attributed to differences in the retarding charge recombination ability of the dye layer. Benefiting from a Marcus inverted region behavior, the M36 dye exhibits a good compatibility with the [Co(phen)3]2+/3+ redox couples, achieving a high overall power conversion efficiency (PCE) of 9.58% under full sun illumination.

  7. Trefoil factor 3 (TFF3) enhances the oncogenic characteristics of prostate carcinoma cells and reduces sensitivity to ionising radiation.

    PubMed

    Perera, Omesha; Evans, Angharad; Pertziger, Mikhail; MacDonald, Christa; Chen, Helen; Liu, Dong-Xu; Lobie, Peter E; Perry, Jo K

    2015-05-28

    Trefoil factor 3 (TFF3) is a secreted protein which functions in mucosal repair of the gastrointestinal tract. This is achieved through the combined stimulation of cell migration and prevention of apoptosis and anoikis, thus facilitating repair. Deregulated TFF3 expression at the gene and protein level is implicated in numerous cancers. In prostate cancer TFF3 has previously been reported as a potential biomarker, overexpressed in a subset of primary and metastatic cases. Here we investigated the effect of increased TFF3 expression on prostate cancer cell behaviour. Oncomine analysis demonstrated that TFF3 mRNA expression was upregulated in prostate cancer compared to normal tissue. Forced-expression models were established in the prostate cancer cell lines, DU145 and PC3, by stable transfection of an expression vector containing the TFF3 cDNA. Forced expression of TFF3 significantly increased total cell number and cell viability, cell proliferation and cell survival. In addition, TFF3 enhanced anchorage independent growth, 3-dimensional colony formation, wound healing and cell migration compared to control transfected cell lines. We also observed reduced sensitivity to ionising radiation in stably transfected cell lines. In dose response experiments, forced expression of TFF3 significantly enhanced the regrowth of PC3 cells following ionising radiation compared with control transfected cells. In addition, TFF3 enhanced clonogenic survival of DU145 and PC3 cells. These studies indicate that targeting TFF3 for the treatment of prostate cancer warrants further investigation.

  8. Controlled drug-release system based on pH-sensitive chloride-triggerable liposomes.

    PubMed

    Wehunt, Mark P; Winschel, Christine A; Khan, Ali K; Guo, Tai L; Abdrakhmanova, Galya R; Sidorov, Vladimir

    2013-03-01

    New pH-sensitive lipids were synthesized and utilized in formulations of liposomes suitable for controlled drug release. These liposomes contain various amounts of NaCl in the internal aqueous compartments. The release of the drug model is triggered by an application of HCl cotransporter and exogenous physiologically relevant NaCl solution. HCl cotransporter allows an uptake of HCl by liposomes to the extent of their being proportional to the transmembrane Cl(-) gradient. Therefore, each set of liposomes undergoes internal acidification, which, ultimately, leads to the hydrolysis of the pH-sensitive lipids and content release at the desired time. The developed system releases the drug model in a stepwise fashion, with the release stages separated by periods of low activity. These liposomes were found to be insensitive to physiological concentrations of human serum albumin and to be nontoxic to cells at concentrations exceeding pharmacological relevance. These results render this new drug-release model potentially suitable for in vivo applications.

  9. Variation of solar cell sensitivity and solar radiation on tilted surfaces

    NASA Technical Reports Server (NTRS)

    Klucher, T. M.

    1978-01-01

    The validity is studied that one of various insolation models used to compute solar radiation incident on tilted surfaces from global data measured on horizontal surfaces. The variation of solar cell sensitivity to solar radiation is determined over a wide range of atmospheric condition. A new model was formulated that reduced the deviations between measured and predicted insolation to less than 3 percent. Evaluation of solar cell sensitivity data indicates small change (2-3 percent) in sensitivity from winter to summer for tilted cells. The feasibility of using such global data as a means for calibrating terrestrial solar cells is discussed.

  10. Relationship between laminin binding capacity and laminin expression on tumor cells sensitive or resistant to natural cell-mediated cytotoxicity

    SciTech Connect

    Laybourn, K.A.; Varani, J.; Fligiel, S.E.G.; Hiserodt, J.C.

    1986-03-01

    Previous studies have identified the presence of laminin binding sites on murine NK and NC sensitive tumor cells by /sup 125/I-laminin binding and laminin induced cell-cell aggregation. The finding that the addition of exogenous laminin inhibits NK/NC binding to sensitive tumor cells suggests laminin binding sites may serve as target antigens for NK cells. The present study extends earlier reports by analyzing a large panel of tumor cells for laminin binding capacity, laminin expression and sensitivity to NK/NC killing. The data indicate that all tumor cells which bind to NK/NC cells (8 lines tested) express laminin binding sites. All of these tumor cells were capable of competing for NK lysis of YAC-1 cells in cold target competition assays, and all bound enriched NK cells in direct single cell binding assays. In contrast, tumor cells expressing high levels of surface laminin (B16 melanomas, C57B1/6 fibrosarcomas, and RAS transfected 3T3 fibroblasts) but low levels of laminin binding capacity did not bind NK/NC cells and were resistant to lysis. These data support the hypothesis that expression of laminin/laminin binding sites may contribute to tumor cell sensitivity to NK/NC binding and/or killing.

  11. Performance of a novel keratinocyte-based reporter cell line to screen skin sensitizers in vitro

    SciTech Connect

    Emter, Roger; Ellis, Graham; Natsch, Andreas

    2010-06-15

    In vitro tests are needed to replace animal tests to screen for the skin sensitization potential of chemicals. Skin sensitizers are electrophilic molecules and the Nrf2-electrophile-sensing pathway comprising the repressor protein Keap1, the transcription factor Nrf2 and the antioxidant response element (ARE) is emerging as a toxicity pathway induced by skin sensitizers. Previously, we screened a large set of chemicals in the reporter cell line AREc32, which contains an eight-fold repeat of the rat GSTA2 ARE-sequence upstream of a luciferase reporter gene in the human breast cancer cell line MCF7. This approach was now further developed to bring it closer to the conditions in the human skin and to propose a fully standardized assay. To this end, a luciferase reporter gene under control of a single copy of the ARE-element of the human AKR1C2 gene was stably inserted into HaCaT keratinocytes. A standard operating procedure was developed whereby chemicals are routinely tested at 12 concentrations in triplicate for significant induction of gene activity. We report results from this novel assay on (i) a list of reference chemicals published by ECVAM, (ii) the ICCVAM list of chemicals for validation of alternative endpoints in the LLNA and (iii) on a more general list of 67 chemicals derived from the ICCVAM database. For comparison, peptide reactivity data are presented for the same chemicals. The results indicate a good predictive value of this approach for hazard identification. Its technical simplicity, the high-throughput format and the good predictivity may make this assay a candidate for rapid validation to meet the tight deadline to replace animal tests for skin sensitization by 2013 set by the European authorities.

  12. Color tuning in new metal-free organic sensitizers (Bodipys) for dye-sensitized solar cells.

    PubMed

    Kumaresan, Duraisamy; Thummel, Randolph P; Bura, Thomas; Ulrich, Gilles; Ziessel, Raymond

    2009-06-22

    Fun in the sun! A strategy has been devised for functionalizing and solubilizing boron dipyrromethene (Bodipy) dyes at the central boron atom and changing the color by increasing delocalization on the central core. This approach leads to the formation of stable B-C[triple bond]C and pyrrole--C=C linkages suitable for use in TiO(2)-sensitized devices (see figure).

  13. Lycopene control of benzophenone-sensitized lipid peroxidation

    NASA Astrophysics Data System (ADS)

    Cvetković, Dragan; Marković, Dejan

    2012-05-01

    Lycopene antioxidant activity in the presence of two different mixtures of phospholipids in hexane solution, under continuous regime of UV-irradiation from three different ranges (UV-A, UV-B, and UV-C) has been evaluated in this work. Lycopene expected role was to control lipid peroxidation, by scavenging free radicals generated by UV-irradiation, in the presence and in the absence of selected photosensitizer, benzophenone. This work shows that lycopene undergoes to UV-induced destruction (bleaching), highly dependent on the incident photons energy input, more expressed in the presence than in the absence of benzophenone. The further increase ("excess") of its bleaching is undoubtedly related to the further increase of its antioxidant activity in the presence of benzophenone, having the same cause: increase of (phospholipids peroxidation) chain-breaking activities.

  14. Realizing omnidirectional light harvesting by employing hierarchical architecture for dye sensitized solar cells.

    PubMed

    Hsieh, Ming-Yang; Lai, Fang-I; Chen, Wei-Chun; Hsieh, Min-Chi; Hu, Hsiang-Yi; Yu, Peichen; Kuo, Hao-Chung; Kuo, Shou-Yi

    2016-03-14

    To improve the omnidirectional light-harvesting in dye-sensitized solar cells (DSSCs), here we present a dandelion-like structure composed of ZnO hemispherical shells and nanorods. Uniformly distributed hemispherical shells effectively suppress the reflection over the broadband region at incident angles up to 60°, greatly improving the optical absorption of the DSSCs. In addition, modulating the length of the ZnO nanorods controls the omnidirectional characteristics of DSSCs. This phenomenon is attributed to the degree of periodicity of the ZnO dandelion-like structures. Cells with shorter rods exhibit a high degree of periodicity, thus the conversion efficiencies of the cells show specific angle-independent features. On the other hand, the cells with longer lengths reveal angle-dependent photovoltaic performance. Along with the simulation, the cells with dandelion-like ZnO structures can couple incident photons efficiently to achieve excellent broadband and omnidirectional light-harvesting performances experimentally, and the DSSCs enhanced the conversion efficiency by 48% at large incident angles. All these findings not only provide further insight into the light-trapping mechanism in these complex three-dimensional nanostructures but also offer efficient omnidirectional and broadband nanostructured photovoltaics for advanced applications. PMID:26899775

  15. Realizing omnidirectional light harvesting by employing hierarchical architecture for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hsieh, Ming-Yang; Lai, Fang-I.; Chen, Wei-Chun; Hsieh, Min-Chi; Hu, Hsiang-Yi; Yu, Peichen; Kuo, Hao-Chung; Kuo, Shou-Yi

    2016-03-01

    To improve the omnidirectional light-harvesting in dye-sensitized solar cells (DSSCs), here we present a dandelion-like structure composed of ZnO hemispherical shells and nanorods. Uniformly distributed hemispherical shells effectively suppress the reflection over the broadband region at incident angles up to 60°, greatly improving the optical absorption of the DSSCs. In addition, modulating the length of the ZnO nanorods controls the omnidirectional characteristics of DSSCs. This phenomenon is attributed to the degree of periodicity of the ZnO dandelion-like structures. Cells with shorter rods exhibit a high degree of periodicity, thus the conversion efficiencies of the cells show specific angle-independent features. On the other hand, the cells with longer lengths reveal angle-dependent photovoltaic performance. Along with the simulation, the cells with dandelion-like ZnO structures can couple incident photons efficiently to achieve excellent broadband and omnidirectional light-harvesting performances experimentally, and the DSSCs enhanced the conversion efficiency by 48% at large incident angles. All these findings not only provide further insight into the light-trapping mechanism in these complex three-dimensional nanostructures but also offer efficient omnidirectional and broadband nanostructured photovoltaics for advanced applications.

  16. [Culture and control of cells producing bovine leukemia virus].

    PubMed

    Granátová, M

    1987-10-01

    In the field surveys of the occurrence of enzootic bovine leucosis caused by the bovine leucosis virus (BLV), the identification of positive animals is based on the detection of specific antiviral antibodies by serological methods. The reliability of these tests (particularly their sensitivity and specificity) depends on the quality of the virus antigen. The preparation of the antigen is based on the cultivation of BLV virus in cultures of the FLS cell line. A modified procedure of preparing the BLV antigen in the FLS cell culture is described, along with the control of its production by the immunoperoxidase test. PMID:2827363

  17. Girls' Rumination and Anxiety Sensitivity: Are They Related after Controlling for Girl, Maternal, and Parenting Factors?

    ERIC Educational Resources Information Center

    Gardner, Christie; Epkins, Catherine C.

    2012-01-01

    Background: Rumination and anxiety sensitivity are posited cognitive vulnerabilities in the development and/or maintenance of depression and anxiety and have only been examined separately in youth. Objective: We examined the relation between rumination and anxiety sensitivity in girls, after controlling for other girl, maternal, and parenting…

  18. In vitro sensitization of human lymphocytes to a myeloma cell-related antigen

    SciTech Connect

    Whitson, M.E.; Griffin, G.D.; Novelli, G.D.; Solomon, A.

    1981-01-01

    Peripheral blood lymphocytes from normal human donors were cocultivated with cells from two established human multiple myeloma cell lines, RPMI 8226 and K-737, and with lymphoblastoid cells from a third B cell line, RAMM. After a comparison of three methods of lymphocyte sensitization, a 6-day incubation protocol with equal numbers of normal lymphocytes and mitomycin C-treated tumor cells was selected. Cells fom the RPMI 8226 myeloma line stimulated the differentiation of lymphocytes into cytotoxic effector cells as measured by /sup 51/Cr release from labeled target cells. The RPMI 8226-sensitized lymphocytes were cytotoxic for myeloma cells (RPMI 8226 and K-737) and for lymphoblastoid cells (RAMM) but not for cells from human lung tumor lines (A549, A427, MB9812), a breast carcinoma line (ALAB), a normal diploid fibroblast line (HSBP), or normal lymphocytes.

  19. Methylation of the ATM promoter in glioma cells alters ionizing radiation sensitivity

    SciTech Connect

    Roy, Kanaklata; Wang, Lilin; Makrigiorgos, G. Mike; Price, Brendan D. . E-mail: brendan_price@dfci.harvard.edu

    2006-06-09

    Glioblastomas are among the malignancies most resistant to radiation therapy. In contrast, cells lacking the ATM protein are highly sensitive to ionizing radiation. The relationship between ATM protein expression and radiosensitivity in 3 glioma cell lines was examined. T98G cells exhibited normal levels of ATM protein, whereas U118 and U87 cells had significantly lower levels of ATM and increased (>2-fold) sensitivity to ionizing radiation compared to T98G cells. The ATM promoter was methylated in U87 cells. Demethylation by azacytidine treatment increased ATM protein levels in the U87 cells and decreased their radiosensitivity. In contrast, the ATM promoter in U118 cells was not methylated. Further, expression of exogenous ATM did not significantly alter the radiosensitivity of U118 cells. ATM expression is therefore heterogeneous in the glioma cells examined. In conclusion, methylation of the ATM promoter may account for the variable radiosensitivity and heterogeneous ATM expression in a fraction of glioma cells.

  20. Enhanced antitumor reactivity of tumor-sensitized T cells by interferon alfa

    SciTech Connect

    Vander Woude, D.L.; Wagner, P.D.; Shu, S.; Chang, A.E. )

    1991-03-01

    Tumor-draining lymph node cells from mice bearing the methylcholanthrene-induced MCA 106 tumors can be sensitized in vitro to acquire antitumor reactivity. We examined the effect of interferon alfa on the function of cells that underwent in vitro sensitization in adoptive immunotherapy. Interferon alfa increased the antitumor reactivity of in vitro sensitized cells in the treatment of MCA 106 pulmonary metastases. This effect was evident in irradiated mice, indicating that a host response to the interferon alfa was not required. Interferon alfa treatment increased class I major histocompatibility complex antigen expression on tumor cells and increased their susceptibility to lysis by in vitro sensitized cells. These results suggest that interferon alfa enhancement of adoptive immunotherapy was mediated by its effect on tumor cells. Interferon alfa may be a useful adjunct to the adoptive immunotherapy of human cancer.

  1. Method of controlled reduction of nitroaromatics by enzymatic reaction with oxygen sensitive nitroreductase enzymes

    DOEpatents

    Shah, M.M.; Campbell, J.A.

    1998-07-07

    A method is described for the controlled reduction of nitroaromatic compounds such as nitrobenzene and 2,4,6-trinitrotoluene by enzymatic reaction with oxygen sensitive nitroreductase enzymes, such as ferredoxin NADP oxidoreductase. 6 figs.

  2. Method of controlled reduction of nitroaromatics by enzymatic reaction with oxygen sensitive nitroreductase enzymes

    DOEpatents

    Shah, Manish M.; Campbell, James A.

    1998-01-01

    A method for the controlled reduction of nitroaromatic compounds such as nitrobenzene and 2,4,6-trinitrotoluene by enzymatic reaction with oxygen sensitive nitroreductase enzymes, such as ferredoxin NADP oxidoreductase.

  3. Fabrication of dye-sensitized solar cell (DSSC) using annato seeds (Bixa orellana Linn)

    SciTech Connect

    Haryanto, Ditia Allindira; Landuma, Suarni; Purwanto, Agus

    2014-02-24

    The Fabrication of dye sensitized solar cell (DSSC) using Annato seeds has been conducted in this study. Annato seeds (Bixa orellana Linn) used as a sensitizer for dye sensitized solar cell. The experimental parameter was concentration of natural dye. Annato seeds was extracted using etanol solution and the concentration was controlled by varying mass of Annato seeds. A semiconductor TiO{sub 2} was prepared by a screen printing method for coating glass use paste of TiO{sub 2}. Construction DSSC used layered systems (sandwich) consists of working electrode (TiO{sub 2} semiconductor-dye) and counter electrode (platina). Both are placed on conductive glass and electrolytes that occur electrons cycle. The characterization of thin layer of TiO{sub 2} was conducted using SEM (Scanning Electron Microscpy) analysis showed the surface morphology of TiO{sub 2} thin layer and the cross section of a thin layer of TiO{sub 2} with a thickness of 15–19 μm. Characterization of natural dye extract was determined using UV-Vis spectrometry analysis shows the wavelength range annato seeds is 328–515 nm, and the voltage (V{sub oc}) and electric current (I{sub sc}) resulted in keithley test for 30 gram, 40 gram, and 50 gram were 0,4000 V; 0,4251 V; 0,4502 V and 0,000074 A; 0,000458 A; 0,000857 A, respectively. The efficiencies of the fabricated solar cells using annato seeds as senstizer for each varying mass are 0,00799%, 0,01237%, and 0,05696%.

  4. Modulation by cyclic GMP of the odour sensitivity of vertebrate olfactory receptor cells

    NASA Technical Reports Server (NTRS)

    Leinders-Zufall, T.; Shepherd, G. M.; Zufall, F.

    1996-01-01

    Recent evidence has indicated a significant role for the cGMP second messenger system in vertebrate olfactory transduction but no clear functions have been identified for cGMP so far. Here, we have examined the effects of 8-Br-cGMP and carbon monoxide (CO) on odour responses of salamander olfactory receptor neurons using perforated patch recordings. We report that 8-Br-cGMP strongly down-regulates the odour sensitivity of the cells, with a K1/2 of 460 nM. This adaptation-like effect can be mimicked by CO, an activator of soluble guanylyl cyclase, with a K1/2 of 1 microM. Sensitivity modulation is achieved through a regulatory chain of events in which cGMP stimulates a persistent background current due to the activation of cyclic nucleotide-gated channels. This in turn leads to sustained Ca2+ entry providing a negative feedback signal. One consequence of the Ca2+ entry is a shift to the right of the stimulus-response curve and a reduction in saturating odour currents. Together, these two effects can reduce the sensory generator current by up to twenty-fold. Thus, cGMP functions to control the gain of the G-protein coupled cAMP pathway. Another consequence of the action of cGMP is a marked prolongation of the odour response kinetics. The effects of CO/cGMP are long-lasting and can continue for minutes. Hence, we propose that cGMP helps to prevent saturation of the cell's response by adjusting the operational range of the cAMP cascade and contributes to olfactory adaptation by decreasing the sensitivity of olfactory receptor cells to repeated odour stimuli.

  5. Towards a controlled sensitivity analysis of model development decisions

    NASA Astrophysics Data System (ADS)

    Clark, Martyn; Nijssen, Bart

    2016-04-01

    The current generation of hydrologic models have followed a myriad of different development paths, making it difficult for the community to test underlying hypotheses and identify a clear path to model improvement. Model comparison studies have been undertaken to explore model differences, but these studies have not been able to meaningfully attribute inter-model differences in predictive ability to individual model components because there are often too many structural and implementation differences among the models considered. As a consequence, model comparison studies to date have provided limited insight into the causes of differences in model behavior, and model development has often relied on the inspiration and experience of individual modelers rather than a systematic analysis of model shortcomings. This presentation will discuss a unified approach to process-based hydrologic modeling to enable controlled and systematic analysis of multiple model representations (hypotheses) of hydrologic processes and scaling behavior. Our approach, which we term the Structure for Unifying Multiple Modeling Alternatives (SUMMA), formulates a general set of conservation equations, providing the flexibility to experiment with different spatial representations, different flux parameterizations, different model parameter values, and different time stepping schemes. We will discuss the use of SUMMA to systematically analyze different model development decisions, focusing on both analysis of simulations for intensively instrumented research watersheds as well as simulations across a global dataset of FLUXNET sites. The intent of the presentation is to demonstrate how the systematic analysis of model shortcomings can help identify model weaknesses and inform future model development priorities.

  6. Infrared-Controlled Welding of Solar Cells

    NASA Technical Reports Server (NTRS)

    Paulson, R.; Finnell, S. E.; Decker, H. J.; Hodor, J. R.

    1982-01-01

    Proposed apparatus for welding large arrays of solar cells to flexible circuit substrates would sense infrared emission from welding spot. Emission would provide feedback for control of welding heat. Welding platform containing optical fibers moves upward through slots in movable holding fixture to contact solar cells. Fibers pick up infrared radiation from weld area.

  7. Controlled surface chemistries and quantitative cell response

    NASA Astrophysics Data System (ADS)

    Plant, Anne L.

    2002-03-01

    Living cells experience a large number of signaling cues from their extracellular matrix. As a result of these inputs, a variety of intracellular signaling pathways are apparently initiated simultaneously. The vast array of alternative responses that result from the integration of these inputs suggests that it may be reasonable to look for cellular response not as an 'on' or 'off' condition but as a distribution of responses. A difficult challenge is to determine whether variations in responses from individual cells arise from the complexity of intracellular signals or are due to variations in the cell culture environment. By controlling surface chemistry so that every cell 'sees' the same chemical and physical environment, we can begin to assess how the distribution of cell response is affected strictly by changes in the chemistry of the cell culture surface. Using the gene for green fluorescent protein linked to the gene for the promoter of the extracellular matrix protein, tenascin, we can easily probe the end product in a signaling pathway that is purported to be linked to surface protein chemistry and to cell shape. Cell response to well-controlled, well-characterized, and highly reproducible surfaces prepared using soft lithography techniques are compared with more conventional ways of preparing extracellular matrix proteins for cell culture. Using fluorescence microscopy and image analysis of populations of cells on these surfaces, we probe quantitatively the relationship between surface chemistry, cell shape and variations in gene expression endpoint.

  8. Losartan sensitizes selectively prostate cancer cell to ionizing radiation.

    PubMed

    Yazdannejat, H; Hosseinimehr, S J; Ghasemi, A; Pourfallah, T A; Rafiei, A

    2016-01-11

    Losartan is an angiotensin II receptor (AT-II-R) blocker that is widely used by human for blood pressure regulation. Also, it has antitumor property. In this study, we investigated the radiosensitizing effect of losartan on cellular toxicity induced by ionizing radiation on prostate cancer and non-malignant fibroblast cells. Human prostate cancer (DU-145) and human non-malignant fibroblast cells (HFFF2) were treated with losartan at different concentrations (0.5, 1, 10, 50 and 100 µM) and then these cells were exposed to ionizing radiation. The cell proliferation was determined using MTT assay. Our results showed that losartan exhibited antitumor effect on prostate cancer cells; it was reduced cell survival to 66% at concentration 1 µM. Losartan showed an additive killing effect in combination with ionizing radiation on prostate cancer cell. The cell proliferation was reduced to 54% in the prostate cancer cells treated with losartan at concentration 1 µM in combination with ionizing radiation. Losartan did not exhibit any toxicity on HFFF2 cell. This result shows a promising effect of losartan on enhancement of therapeutic effect of ionizing radiation in patients during therapy.

  9. Disruption of Annexin II /p11 Interaction Suppresses Leukemia Cell Binding, Homing and Engraftment, and Sensitizes the Leukemia Cells to Chemotherapy

    PubMed Central

    Gopalakrishnapillai, Anilkumar; Kolb, E. Anders; Dhanan, Priyanka; Mason, Robert W.; Napper, Andrew; Barwe, Sonali P.

    2015-01-01

    The bone marrow microenvironment plays an important role in acute lymphoblastic leukemia (ALL) cell proliferation, maintenance, and resistance to chemotherapy. Annexin II (ANX2) is abundantly expressed on bone marrow cells and complexes with p11 to form ANX2/p11-hetero-tetramer (ANX2T). We present evidence that p11 is upregulated in refractory ALL cell lines and patient samples. A small molecule inhibitor that disrupts ANX2/p11 interaction (ANX2T inhibitor), an anti-ANX2 antibody, and knockdown of p11, abrogated ALL cell adhesion to osteoblasts, indicating that ANX2/p11 interaction facilitates binding and retention of ALL cells in the bone marrow. Furthermore, ANX2T inhibitor increased the sensitivity of primary ALL cells co-cultured with osteoblasts to dexamethasone and vincristine induced cell death. Finally, in an orthotopic leukemia xenograft mouse model, the number of ALL cells homing to the bone marrow was reduced by 40–50% in mice injected with anti-ANX2 antibody, anti-p11 antibody or ANX2T inhibitor compared to respective controls. In a long-term engraftment assay, the percentage of ALL cells in mouse blood, bone marrow and spleen was reduced in mice treated with agents that disrupt ANX2/p11 interaction. These data show that disruption of ANX2/p11 interaction results in reduced ALL cell adhesion to osteoblasts, increased ALL cell sensitization to chemotherapy, and suppression of ALL cell homing and engraftment. PMID:26465153

  10. [Enhanced control of proliferation in telomerized cells].

    PubMed

    Egorov, E E; Moldaver, M V; Vishniakova, Kh S; Terekhov, S M; Dashinimaev, E B; Cheglakov, I B; Toropygin, I Iu; Iarygin, K N; Chumakov, P M; Korochkin, L I; Antonova, G A; Rybalkina, E Iu; Saburina, I N; Burnaevskiĭ, N S; Zelenin, A V

    2007-01-01

    Clones of telomerized fibroblasts of adult human skin have earlier been obtained. It was shown that despite their fast growth in mass cultures, these cells poorly form colonies. Conditioned medium, antioxidants, and reduced partial oxygen pressure enhanced their colony formation, but not to the level characteristic of the initial cells. The conditioned medium of telomerized cells enhanced colony formation to a much greater extent than that of the initial cells. A study of proteome of the telomerized fibroblasts has revealed changes in the activities of tens of genes. A general trend consists in weakening and increased lability of the cytoskeleton and in activation of the mechanisms controlling protein degradation. However, these changes are not very pronounced. During the formation of immortal telomerized cells, selection takes place, which appears to determine changes in the expression of some genes. It was proposed that a decrease in the capacity of telomerized cells for colony formation is due to increased requirements of these cells to cell-cell contacts. The rate of cell growth reached that characteristic of mass cultures only in the largest colonies. In this respect, the telomerized fibroblasts resembled stem cells: they are capable of self-maintenance, but "escape" to differentiation in the absence of the corresponding microenvironment (niche), which is represented by other fibroblasts. Non-dividing cells in the test of colony formation should be regarded as differentiated cells, since they have no features of degradation, preserve their viability, actively move, grow, phagocytized debris, etc. It was also shown that telomerization did not prevent differentiation of myoblasts and human neural stem cells. Thus, the results obtained suggest the existence of normal mechanisms underlying the regulation of proliferation in the telomerized cells, which opens possibilities of their use in cell therapy, especially in the case of autotransplantation to senior people

  11. Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ananth, S.; Vivek, P.; Arumanayagam, T.; Murugakoothan, P.

    2014-07-01

    Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC.

  12. Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells.

    PubMed

    Ananth, S; Vivek, P; Arumanayagam, T; Murugakoothan, P

    2014-07-15

    Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC.

  13. Immune cells control skin lymphatic electrolyte homeostasis and blood pressure.

    PubMed

    Wiig, Helge; Schröder, Agnes; Neuhofer, Wolfgang; Jantsch, Jonathan; Kopp, Christoph; Karlsen, Tine V; Boschmann, Michael; Goss, Jennifer; Bry, Maija; Rakova, Natalia; Dahlmann, Anke; Brenner, Sven; Tenstad, Olav; Nurmi, Harri; Mervaala, Eero; Wagner, Hubertus; Beck, Franz-Xaver; Müller, Dominik N; Kerjaschki, Dontscho; Luft, Friedrich C; Harrison, David G; Alitalo, Kari; Titze, Jens

    2013-07-01

    The skin interstitium sequesters excess Na+ and Cl- in salt-sensitive hypertension. Mononuclear phagocyte system (MPS) cells are recruited to the skin, sense the hypertonic electrolyte accumulation in skin, and activate the tonicity-responsive enhancer-binding protein (TONEBP, also known as NFAT5) to initiate expression and secretion of VEGFC, which enhances electrolyte clearance via cutaneous lymph vessels and increases eNOS expression in blood vessels. It is unclear whether this local MPS response to osmotic stress is important to systemic blood pressure control. Herein, we show that deletion of TonEBP in mouse MPS cells prevents the VEGFC response to a high-salt diet (HSD) and increases blood pressure. Additionally, an antibody that blocks the lymph-endothelial VEGFC receptor, VEGFR3, selectively inhibited MPS-driven increases in cutaneous lymphatic capillary density, led to skin Cl- accumulation, and induced salt-sensitive hypertension. Mice overexpressing soluble VEGFR3 in epidermal keratinocytes exhibited hypoplastic cutaneous lymph capillaries and increased Na+, Cl-, and water retention in skin and salt-sensitive hypertension. Further, we found that HSD elevated skin osmolality above plasma levels. These results suggest that the skin contains a hypertonic interstitial fluid compartment in which MPS cells exert homeostatic and blood pressure-regulatory control by local organization of interstitial electrolyte clearance via TONEBP and VEGFC/VEGFR3-mediated modification of cutaneous lymphatic capillary function. PMID:23722907

  14. Size sensors in bacteria, cell cycle control, and size control

    PubMed Central

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation. PMID:26074903

  15. Size sensors in bacteria, cell cycle control, and size control.

    PubMed

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation.

  16. Inhaled lead affects lung pathology and inflammation in sensitized and control guinea pigs.

    PubMed

    Boskabady, Mohammad Hossein; Tabatabai, Sayed Abas; Farkhondeh, Tahereh

    2016-04-01

    The association between lead exposure and respiratory diseases including asthma is controversial. Some studies indicate that exposure to environmental lead pollution may cause asthma; however, there is not sufficient data in this regard. The effect of lead on lung pathological findings and serum inflammatory mediators in sensitized and non-sensitized guinea pigs exposed to inhaled lead was examined. Eleven animal groups including control, sensitized, three groups of non sensitized animals, three groups during sensitization, and three groups after sensitization exposed to aerosol of three lead concentrations (n = 6 for each group) were studied. Serum inflammatory mediators levels and lung pathological changes were evaluated. All pathological changes and serum ET-1, EPO, NO levels were significantly higher in the sensitized and non sensitized animals exposed to lead than control group (p < 0.05 to p < 0.001). There was no significant difference between non sensitized groups exposed to high lead concentration and sensitized group. Serum inflammatory mediators levels and pathological findings in sensitized groups exposed to lead both during and after sensitization were significantly higher than sensitized non exposed group (p < 0.05 to p < 0.001). The data of exposed animals to high lead concentration were significantly higher than those of medium and low concentrations; those of medium concentration were also higher than low concentration (p < 0.05 to p < 0.001). In summary, the present study indicates that exposure to inhaled lead is able to induce respiratory changes similar to asthma. In addition, the results indicated that exposure to environmental lead is able to aggravate asthma severity both during development of asthma or after its manifestation.

  17. X-ray sensitivity of human tumor cells in vitro

    SciTech Connect

    Weichselbaum, R.R.; Nove, J.; Little, J.B.

    1980-04-01

    Clonally-derived cells from ten human malignant tumors considered radiocurable (breast, neuroblastoma, medulloblastoma) or non-radiocurable (osteosarcoma, hypernephroma, glioblastoma, melanoma) were studied in cell culture and their in vitro x-ray survival curve parameters determined (anti n, D/sub 0/). There were no significant differences among the tumor cell lines suggesting that survival parameters in vitro do not explain differences in clinical radiocurability. Preliminary investigation with density inhibited human tumor cells indicate that such an approach may yield information regarding inherent cellular differences in radiocurability.

  18. Shape-controlled ceria-reduced graphene oxide nanocomposites toward high-sensitive in situ detection of nitric oxide.

    PubMed

    Hu, Fang Xin; Xie, Jia Le; Bao, Shu Juan; Yu, Ling; Li, Chang Ming

    2015-08-15

    Nitric oxide (NO) is an important signal molecule released by most cancer cells under drug stimulation or/and disease development but it is extremely challenging to in situ while real-time sensitively detect NO due to its large diffusivity, low concentration and fast decay. Herein, shape-controlled reduced graphene oxide nanocomposing with ceria (rGO-CeO2) was synthesized via hydrothermal reaction to construct a highly sensitive real-time sensing platform for NO detection. The crystal shape of CeO2 nanoparticles in rGO-CeO2 composites significantly affects the sensing performance of rGO-CeO2, of which the regular hexagonal nanocrystal CeO2 achieves the highest sensitivity (1676.06 mA cm(-2) M(-1)), a wide dynamic range (18.0 nM to 5.6 µM) and a low detection limit (9.6 nM). This attributes to a synergical effect from high catalytic activity of the specifically shaped CeO2 nanocrystal and good conductivity/high surface area of rGO. This work demonstrates a way by rationally compose individual merit components while well control the nanostructure for a superior synergistic effect to build a smart sensing platform, while offering a great application potential to sensitively real-time detect NO released from living cells for diagnosis or/and studies of complicated biological processes.

  19. Photoelectrochemical cell/dye-sensitized solar cell tandem water splitting systems with transparent and vertically aligned quantum dot sensitized TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Shin, Kahee; Yoo, Ji-Beom; Park, Jong Hyeok

    2013-03-01

    The present work reports fabrication of vertically aligned CdS sensitized TiO2 nanorod arrays grown on transparent conducting oxide substrate with high transparency as a photoanode in photoelectrochemical cell for water splitting. To realize an unassisted water splitting system, the photoanode and dye-sensitized solar cell tandem structures are tried and their electrochemical behaviors are also investigated. The hydrothermally grown TiO2 nanorod arrays followed by CdS nanoparticle decoration can improve the light absorption of long wavelength light resulting in increased photocurrent density. Two different techniques (electrodeposition and spray pyrolysis deposition) of CdS nanoparticle sensitization are carried out and their water splitting behaviors in the tandem cell are compared.

  20. Fuel cell stack monitoring and system control

    DOEpatents

    Keskula, Donald H.; Doan, Tien M.; Clingerman, Bruce J.

    2005-01-25

    A control method for monitoring a fuel cell stack in a fuel cell system in which the actual voltage and actual current from the fuel cell stack are monitored. A preestablished relationship between voltage and current over the operating range of the fuel cell is established. A variance value between the actual measured voltage and the expected voltage magnitude for a given actual measured current is calculated and compared with a predetermined allowable variance. An output is generated if the calculated variance value exceeds the predetermined variance. The predetermined voltage-current for the fuel cell is symbolized as a polarization curve at given operating conditions of the fuel cell. Other polarization curves may be generated and used for fuel cell stack monitoring based on different operating pressures, temperatures, hydrogen quantities.

  1. Metabolic control of the cell cycle

    PubMed Central

    Kalucka, Joanna; Missiaen, Rindert; Georgiadou, Maria; Schoors, Sandra; Lange, Christian; De Bock, Katrien; Dewerchin, Mieke; Carmeliet, Peter

    2015-01-01

    Cell division is a metabolically demanding process, requiring the production of large amounts of energy and biomass. Not surprisingly therefore, a cell's decision to initiate division is co-determined by its metabolic status and the availability of nutrients. Emerging evidence reveals that metabolism is not only undergoing substantial changes during the cell cycle, but it is becoming equally clear that metabolism regulates cell cycle progression. Here, we overview the emerging role of those metabolic pathways that have been best characterized to change during or influence cell cycle progression. We then studied how Notch signaling, a key angiogenic pathway that inhibits endothelial cell (EC) proliferation, controls EC metabolism (glycolysis) during the cell cycle. PMID:26431254

  2. Magnesium homeostasis in colon carcinoma LoVo cells sensitive or resistant to doxorubicin.

    PubMed

    Castiglioni, Sara; Cazzaniga, Alessandra; Trapani, Valentina; Cappadone, Concettina; Farruggia, Giovanna; Merolle, Lucia; Wolf, Federica I; Iotti, Stefano; Maier, Jeanette A M

    2015-11-13

    Neoplastic cells accumulate magnesium, an event which provides selective advantages and is frequently associated with TRPM7 overexpression. Little is known about magnesium homeostasis in drug-resistant cancer cells. Therefore, we used the colon cancer LoVo cell model and compared doxorubicin-resistant to sensitive cells. In resistant cells the concentration of total magnesium is higher while its influx capacity is lower than in sensitive cells. Accordingly, resistant cells express lower amounts of the TRPM6 and 7, both involved in magnesium transport. While decreased TRPM6 levels are due to transcriptional regulation, post-transcriptional events are involved in reducing the amounts of TRPM7. Indeed, the calpain inhibitor calpeptin markedly increases the levels of TRPM7 in resistant cells. In doxorubicin-sensitive cells, silencing TRPM7 shifts the phenotype to one more similar to resistant cells, since in these cells silencing TRPM7 significantly decreases the influx of magnesium, increases its intracellular concentration and increases resistance to doxorubicin. On the other hand, calpain inhibition upregulates TRPM7, decreases intracellular magnesium and enhances the sensitivity to doxorubicin of resistant LoVo cells. We conclude that in LoVo cells drug resistance is associated with alteration of magnesium homeostasis through modulation of TRPM7. Our data suggest that TRPM7 expression may be an additional undisclosed player in chemoresistance.

  3. Magnesium homeostasis in colon carcinoma LoVo cells sensitive or resistant to doxorubicin

    PubMed Central

    Castiglioni, Sara; Cazzaniga, Alessandra; Trapani, Valentina; Cappadone, Concettina; Farruggia, Giovanna; Merolle, Lucia; Wolf, Federica I.; Iotti, Stefano; Maier, Jeanette A M

    2015-01-01

    Neoplastic cells accumulate magnesium, an event which provides selective advantages and is frequently associated with TRPM7overexpression. Little is known about magnesium homeostasis in drug-resistant cancer cells. Therefore, we used the colon cancer LoVo cell model and compared doxorubicin-resistant to sensitive cells. In resistant cells the concentration of total magnesium is higher while its influx capacity is lower than in sensitive cells. Accordingly, resistant cells express lower amounts of the TRPM6 and 7, both involved in magnesium transport. While decreased TRPM6 levels are due to transcriptional regulation, post-transcriptional events are involved in reducing the amounts of TRPM7. Indeed, the calpain inhibitor calpeptin markedly increases the levels of TRPM7 in resistant cells. In doxorubicin-sensitive cells, silencing TRPM7 shifts the phenotype to one more similar to resistant cells, since in these cells silencing TRPM7 significantly decreases the influx of magnesium, increases its intracellular concentration and increases resistance to doxorubicin. On the other hand, calpain inhibition upregulates TRPM7, decreases intracellular magnesium and enhances the sensitivity to doxorubicin of resistant LoVo cells. We conclude that in LoVo cells drug resistance is associated with alteration of magnesium homeostasis through modulation of TRPM7. Our data suggest that TRPM7 expression may be an additional undisclosed player in chemoresistance. PMID:26563869

  4. pH-sensitive strontium carbonate nanoparticles as new anticancer vehicles for controlled etoposide release

    PubMed Central

    Qian, Wen-Yu; Sun, Dong-Mei; Zhu, Rong-Rong; Du, Xi-Ling; Liu, Hui; Wang, Shi-Long

    2012-01-01

    Strontium carbonate nanoparticles (SCNs), a novel biodegradable nanosystem for the pH-sensitive release of anticancer drugs, were developed via a facile mixed solvent method aimed at creating smart drug delivery in acidic conditions, particularly in tumor environments. Structural characterization of SCNs revealed that the engineered nanocarriers were uniform in size and presented a dumbbell-shaped morphology with a dense mass of a scale-like spine coating, which could serve as the storage structure for hydrophobic drugs. Chosen as a model anticancer agent, etoposide was effectively loaded into SCNs based on a simultaneous process that allowed for the formation of the nanocarriers and for drug storage to be accomplished in a single step. The etoposide-loaded SCNs (ESCNs) possess both a high loading capacity and efficient encapsulation. It was found that the cumulative release of etoposide from ESCNs is acid-dependent, and that the release rate is slow at a pH of 7.4; this rate increases significantly at low pH levels (5.8, 3.0). Meanwhile, it was also found that the blank SCNs were almost nontoxic to normal cells, and ESCN systems were evidently more potent in antitumor activity compared with free etoposide, as confirmed by a cytotoxicity test using an MTT assay and an apoptosis test with fluorescence-activated cell sorter (FACS) analysis. These findings suggest that SCNs hold tremendous promise in the areas of controlled drug delivery and targeted cancer therapy. PMID:23185118

  5. RIG-I-like helicases induce immunogenic cell death of pancreatic cancer cells and sensitize tumors toward killing by CD8+ T cells

    PubMed Central

    Duewell, P; Steger, A; Lohr, H; Bourhis, H; Hoelz, H; Kirchleitner, S V; Stieg, M R; Grassmann, S; Kobold, S; Siveke, J T; Endres, S; Schnurr, M

    2014-01-01

    Pancreatic cancer is characterized by a microenvironment suppressing immune responses. RIG-I-like helicases (RLH) are immunoreceptors for viral RNA that induce an antiviral response program via the production of type I interferons (IFN) and apoptosis in susceptible cells. We recently identified RLH as therapeutic targets of pancreatic cancer for counteracting immunosuppressive mechanisms and apoptosis induction. Here, we investigated immunogenic consequences of RLH-induced tumor cell death. Treatment of murine pancreatic cancer cell lines with RLH ligands induced production of type I IFN and proinflammatory cytokines. In addition, tumor cells died via intrinsic apoptosis and displayed features of immunogenic cell death, such as release of HMGB1 and translocation of calreticulin to the outer cell membrane. RLH-activated tumor cells led to activation of dendritic cells (DCs), which was mediated by tumor-derived type I IFN, whereas TLR, RAGE or inflammasome signaling was dispensable. Importantly, CD8α+ DCs effectively engulfed apoptotic tumor material and cross-presented tumor-associated antigen to naive CD8+ T cells. In comparison, tumor cell death mediated by oxaliplatin, staurosporine or mechanical disruption failed to induce DC activation and antigen presentation. Tumor cells treated with sublethal doses of RLH ligands upregulated Fas and MHC-I expression and were effectively sensitized towards Fas-mediated apoptosis and cytotoxic T lymphocyte (CTL)-mediated lysis. Vaccination of mice with RLH-activated tumor cells induced protective antitumor immunity in vivo. In addition, MDA5-based immunotherapy led to effective tumor control of established pancreatic tumors. In summary, RLH ligands induce a highly immunogenic form of tumor cell death linking innate and adaptive immunity. PMID:25012502

  6. Perillyl alcohol and methyl jasmonate sensitize cancer cells to cisplatin.

    PubMed

    Yeruva, Laxmi; Hall, Casey; Elegbede, John Abiodun; Carper, Stephen W

    2010-01-01

    Breast cancer is the second leading cause of cancer deaths among women in the United States. Several treatment options exist, with different side effects. To alleviate the side effects, several research groups have studied chemotherapeutic effects of plant compounds on cancer cells. These could be used as an alternative treatment option either alone or in combination with other chemotherapeutic drugs. The aim of this study was to evaluate the activity of a combination of perillyl alcohol (POH), methyl jasmonate (MJ) with cisplatin to define the most effective schedule and to investigate the mechanism of action in breast cancer cells. POH and MJ treatment (20% decrease in cell viability concentration) enhanced the cytotoxicity for subsequent exposure to cisplatin in MDA-MB-435 and MDA-MB-231 cells. Combination treatment of POH and MJ blocked cells at the G0/G1 phase of the cell cycle and the addition of cisplatin forced the cells to progress through the cell cycle and induced apoptosis. Apoptotic mechanistic studies indicated that POH and MJ treatment activated tumor necrosis factor receptor 1 and this was further increased by the addition of cisplatin. It was also found that mitochondrial membrane potential decreased with POH and MJ treatment; this effect was further enhanced by cisplatin treatment. These findings contributed to a better understanding of molecular mechanism of apoptosis in combination treatment of POH, MJ, and cisplatin. Results also showed that the combination treatment of three drugs is more effective than single drug alone or two drugs together.

  7. Rainbow trout cell bioassay-derived relative potencies for halogenated aromatic hydrocarbons: Comparison and sensitivity analysis

    SciTech Connect

    Villeneuve, D.L.; Blankenship, A.L.; Giesy, J.P.; Richter, C.A.

    1999-05-01

    Rainbow trout hepatoma cells, stably transfected with a luciferase reporter gene under control of dioxin-responsive elements (RLT 2.0 cells) were used to derive relative potencies (RPs) for a variety of halogenated aromatic hydrocarbons (HAHs) that are structurally similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This in vitro bioassay utilizes 96-well microplates, which provide high sample throughput and assay efficiency without affecting sensitivity. The RLT 2.0-derived potencies for dioxin and furan congeners, relative to 2,3,7,8-TCDD, ranged from 0.917 for 1,2,3,4,7,8-hexachlorodibenzofuran to 0.208 or 1,2,3,7,8-pentachlorodibenzofuran. All mono- and di-ortho polychlorinated biphenyls (PCBs) tested had RPs that were orders of magnitude less than TCDD, but point estimates could not be determined. The RLT 2.0-derived RPs were found to be comparable to both other rainbow trout-specific RPs and RPs based on mammalian bioassays. Sensitivity analysis suggested that the range of uncertainty associated with TCDD equivalent (TEQ) estimates based on RLT 2.0-derived RPs is approximately 10-fold. Within this degree of uncertainty and the context of this study, the RLT 2.0 bioassay showed no definitive biases or inaccuracies relative to similar mammalian- or fish-specific in vitro bioassays. Thus, the RLT 2.0 bioassay appears to be a useful tool for evaluating dioxin-like potency of HAHs to fish.

  8. ROS-dependent phosphorylation of Bax by wortmannin sensitizes melanoma cells for TRAIL-induced apoptosis

    PubMed Central

    Quast, S-A; Berger, A; Eberle, J

    2013-01-01

    The pathways of reactive oxygen species (ROS)-mediated apoptosis induction, of Bax activation and the sensitization of tumor cells for TRAIL (TNF-related apoptosis-inducing ligand)-induced apoptosis are still largely elusive. Here, sensitization of melanoma cells for TRAIL by the PI3-kinase inhibitor wortmannin correlated to the activation of mitochondrial apoptosis pathways. Apoptosis was dependent on Bax and abrogated by Bcl-2 overexpression. The synergistic enhancement was explained by Bax activation through wortmannin, which tightly correlated to the characteristic Bax phosphorylation patterns. Thus, wortmannin resulted in early reduction of the Bax-inactivating phosphorylation at serine-184, whereas the Bax-activating phosphorylation at threonine-167 was enhanced. Proving the responsibility of the pathway, comparable effects were obtained with an Akt inhibitor (MK-2206); while suppressed phosphorylation of serine-184 may be attributed to reduced Akt activity itself, the causes of enhanced threonine-167 phosphorylation were addressed here. Characteristically, production of ROS was seen early in response to wortmannin and MK-2206. Providing the link between ROS and Bax, we show that abrogated ROS production by α-tocopherol or by NADPH oxidase 4 (NOX4) siRNA suppressed apoptosis and Bax activation. This correlated with reduced Bax phosphorylation at threonine-167. The data unraveled a mechanism by which NOX4-dependent ROS production controls apoptosis via Bax phosphorylation. The pathway may be considered for proapoptotic, anticancer strategies. PMID:24113173

  9. Motion and vibration control of a slewing flexible structure by SMA actuators and parameter sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Janzen, F. C.; Tusset, A. M.; Piccirillo, V.; Balthazar, J. M.; Brasil, R. M. L. R. F.

    2015-11-01

    This work presents two approaches to the problem of vibration and positioning control of a flexible structural beam driven by a DC motor. The position is controlled by the current applied to the DC motor armature. A Shape Memory Alloy (SMA) actuator controls vibrations of the flexible structural beam. The State Dependent Riccati Equation (SDRE) technique is used to provide a control action which uses sub-optimal control and system local stability search. The robustness of these two controllers is tested by sensitivity analysis to parametric uncertainties. Numerical simulations results are presented to demonstrate the effectiveness of the proposed control strategy.

  10. Cycloheximide-sensitive recovery from 254 nm UV light damage in cultured marsupial cells.

    PubMed

    Hoy, C A; Rupert, C S

    1984-08-01

    Colony-forming ability of Potorous tridactylus-kidney (PtK-2) cells was measured after exposure to 254-nm ultraviolet (UV) light and cycloheximide. Addition of 5 microM cycloheximide after exposure of the cells to UV light greatly decreased cell survival. Maximum effect of the drug was obtained by 24-h exposure after irradiation. The cycloheximide sensitivity of irradiated cells was eliminated if addition of the drug was delayed for 8-10 h after irradiation, or if the cells received photoreactivating light treatment prior to cycloheximide exposure. Thus, a major component of pyrimidine dimer removal may involve a cycloheximide-sensitive mechanism.

  11. Targeting cholesterol synthesis increases chemoimmuno-sensitivity in chronic lymphocytic leukemia cells

    PubMed Central

    2014-01-01

    Background Cholesterol plays an important role in cancer development, drug resistance and chemoimmuno-sensitivity. Statins, cholesterol lowering drugs, can induce apoptosis, but also negatively interfere with CD-20 and rituximab-mediated activity. Our goal is to identify the alternative targets that could reduce cholesterol levels but do not interfere with CD-20 in chemo immunotherapy of chronic lymphocytic leukemia (CLL). Methods MEC-2 cells, a CLL cell line, and the peripheral blood mononuclear cells (PBMCs) from CLL patients were treated with cholesterol lowering agents, and analyzed the effect of these agents on cholesterol levels, CD-20 expression and distribution, and cell viability in the presence or absence of fludarabine, rituximab or their combinations. Results We found that MEC-2 cells treated with cholesterol lowering agents (BIBB-515, YM-53601 or TAK-475) reduced 20% of total cellular cholesterol levels, but also significantly promoted CD-20 surface expression. Furthermore, treatment of cells with fludarabine, rituximab or their combinations in the presence of BIBB-515, YM-53601 or TAK-475 enhanced MEC-2 cell chemoimmuno-sensitivity measured by cell viability. More importantly, these cholesterol lowering agents also significantly enhanced chemoimmuno-sensitivity of the PBMCs from CLL patients. Conclusion Our data demonstrate that BIBB-515, YM53601 and TAK-475 render chemoimmuno-therapy resistant MEC-2 cells sensitive to chemoimmuno-therapy and enhance CLL cell chemoimmuno-sensitivity without CD-20 epitope presentation or its downstream signaling. These results provide a novel strategy which could be applied to CLL treatment. PMID:25401046

  12. Coumarin-bearing triarylamine sensitizers with high molar extinction coefficient for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhong, Changjian; Gao, Jianrong; Cui, Yanhong; Li, Ting; Han, Liang

    2015-01-01

    Coumarin unit is introduced into triarylamine and three organic sensitizers are designed and synthesized with triarylamine bearing coumarin moiety as the electron donor, conjugated system containing thiophene unit as the π-bridge, and cyanoacetic acid moiety as the electron acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes are investigated systematically with the comparison of different π-bridges. High molar extinction coefficients are observed in these triarylamine dyes and the photocurrent and photovoltage are increased with the introduction of another thiophene or benzene. Optimal photovoltaic performance (η = 6.24%, Voc = 690 mV, Jsc = 14.33 mA cm-2, and ff = 0.63) is observed in the DSSC based on dye with thiophene-phenyl unit as the π-conjugated bridge under 100 mW cm-2 simulated AM 1.5 G solar irradiation.

  13. Independent, reciprocal neuromodulatory control of sweet and bitter taste sensitivity during starvation in Drosophila

    PubMed Central

    Inagaki, Hidehiko K.; Panse, Ketaki; Anderson, David J.

    2015-01-01

    SUMMARY An organism’s behavioral decisions often depend upon the relative strength of appetitive and aversive sensory stimuli, the relative sensitivity to which can be modified by internal states like hunger. However, whether sensitivity to such opposing influences is modulated in a unidirectional or bidirectional manner is not clear. Starved flies exhibit increased sugar and decreased bitter sensitivity. It is widely believed that only sugar sensitivity changes, and that this masks bitter sensitivity. Here we use gene- and circuit-level manipulations to show that sweet- and bitter-sensitivity are independently and reciprocally regulated by starvation in Drosophila. We identify orthogonal neuromodulatory cascades that oppositely control peripheral taste sensitivity for each modality. Moreover, these pathways are recruited at increasing hunger levels, such that low-risk changes (higher sugar sensitivity) precede high-risk changes (lower sensitivity to potentially toxic resources). In this way, state intensity-dependent, reciprocal regulation of appetitive and aversive peripheral gustatory sensitivity permits flexible, adaptive feeding-decisions. PMID:25451195

  14. Cell sorting analysis of cell cycle-dependent X-ray sensitivity in end joining-deficient human cells

    SciTech Connect

    Iwabuchi, Kuniyoshi Hashimoto, Mitsumasa; Matsui, Tadashi; Kurosawa, Aya; Adachi, Noritaka; Date, Takayasu

    2008-08-08

    Non-homologous end joining (NHEJ) plays a major role in the repair of ionizing radiation-induced DNA double-strand breaks (DSBs), especially during the G1-phase of the cell cycle. Using a flow cytometric cell sorter, we fractionated G1- and S/G2-phase cells based on size to assess the DSB-repair activity in NHEJ factor-deficient DT40 and Nalm-6 cell lines. Colony formation assays revealed that the X-ray sensitivities of the G1-enriched populations correctly reflected the DSB-repair activities of both the DT40 and Nalm-6 cell lines. Furthermore, as assessed by {gamma}-H2AX foci formation, the sorted cells exhibited less DNA damage than chemically synchronized cells. Given that it does not use fluorescent labeling or chemical agents, this method of cell sorting is simpler and less toxic than other methods, making it applicable to a variety of cell lines, including those that cannot be synchronized by standard chemical treatments.

  15. Oxygen radical detoxification enzymes in doxorubicin-sensitive and -resistant P388 murine leukemia cells

    SciTech Connect

    Ramu, A.; Cohen, L.; Glaubiger, D.

    1984-05-01

    One of the proposed mechanisms for the cytotoxic effects of anthracycline compounds suggests that the effect is mediated through the formation of intracellular superoxide radicals. It is therefore possible that doxorubicin resistance is associated with increased intracellular enzyme capacity to convert these superoxide radicals to inactive metabolites. We have measured the relative activities of superoxide dismutase, glutathione peroxidase, and catalase in P388 mouse leukemia cells and in a doxorubicin-resistant subline. Since oxygen-reactive metabolites also play a role in mediating the cytotoxicity of ionizing radiation, the radiosensitivity of both cell lines was also studied. No significant differences in superoxide dismutase activity between these cell lines was observed, indicating that they have a similar capacity to convert superoxide anion radicals to hydrogen peroxide. P388 cells that are resistant to doxorubicin have 1.5 times the glutathione content and 1.5 times the activity of glutathione peroxidase measured in drug-sensitive P388 cells. However, incubation with 1-chloro-2,4-dinitrobenzene, which covalently binds glutathione, had no effect on the sensitivity of either cell line to doxorubicin. Measured catalase activity in drug-resistant P388 cells was one-third of the activity measured in doxorubicin-sensitive P388 cells. The activity of this enzyme was much higher than that of glutathione peroxidase in terms of H/sub 2/O/sub 2/ deactivation in both cell lines. It is therefore unlikely that doxorubicin-resistant P388 cells have an increased ability to detoxify reactive oxygen metabolites when compared to drug-sensitive cells. Doxorubicin-resistant P388 cells were significantly more sensitive to X-irradiation than were drug-sensitive P388 cells. These observations suggest that the difference in catalase activity in these cell lines may be associated with the observed differences in radiosensitivity.

  16. Synthesis and characterization of Allium cepa L. as photosensitizer of dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Sutikno, Afrian, Noverdi; Supriadi, Putra, Ngurah Made Dharma

    2016-04-01

    The synthesis and characterization of Allium cepa L. used as natural pigment for natural dye sensitizer of solar cell has successfully done and anthocyanin is extracted. Anthocynin is color pigment of plant which has characteristic absorption spectrum of photon and excites electrons up to pigment molecules. As the anthocyanin absorbed light increases the excited electrons increase as well. The generated current also increases and it leads to the efficiency increase. The energy conversion efficiency of the cells sensitized with dye of Allium cepa L. was 3,045 x 10-4%. A simple technique was taken to fabricate dye sensitizer solar cell is spincoating.

  17. EH AND S ANALYSIS OF DYE-SENSITIZED PHOTOVOLTAIC SOLAR CELL PRODUCTION.

    SciTech Connect

    BOWERMAN,B.; FTHENAKIS,V.

    2001-10-01

    Photovoltaic solar cells based on a dye-sensitized nanocrystalline titanium dioxide photoelectrode have been researched and reported since the early 1990's. Commercial production of dye-sensitized photovoltaic solar cells has recently been reported in Australia. In this report, current manufacturing methods are described, and estimates are made of annual chemical use and emissions during production. Environmental, health and safety considerations for handling these materials are discussed. This preliminary EH and S evaluation of dye-sensitized titanium dioxide solar cells indicates that some precautions will be necessary to mitigate hazards that could result in worker exposure. Additional information required for a more complete assessment is identified.

  18. Carbon coated stainless steel as counter electrode for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Prakash, Shejale Kiran; Sharma, Rakesh K.; Roy, Mahesh S.; Kumar, Mahesh

    2014-10-01

    A new type of counter electrode for dye sensitized solar cells has been fabricated using a stainless steel sheet as substrate and graphite, graphene and multiwall carbon nanotubes as the catalytic material which applied by screen printing technique. The sheet resistances of the substrates and there influence on the dye sensitized solar cells has been studied. The fabricated counter electrodes i.e. SS-graphite, SS-graphene SS-MWCNT and SS-platinum were tested for their photovoltaic response in the form of dye sensitized solar cells.

  19. Inhibition of glutamine metabolism counteracts pancreatic cancer stem cell features and sensitizes cells to radiotherapy

    PubMed Central

    Zhao, Xiaohui; Zhou, Yu; Zeng, Bing; Yu, Min; Zhou, Quanbo; Lin, Qing; Gao, Wenchao; Ye, Huilin; Zhou, Jiajia; Li, Zhihua; Liu, Yimin; Chen, Rufu

    2015-01-01

    Pancreatic ductal adenocarcinoma (PDAC) cells utilize a novel non-canonical pathway of glutamine metabolism that is essential for tumor growth and redox balance. Inhibition of this metabolic pathway in PDAC can potentially synergize with therapies that increase intracellular reactive oxygen species (ROS) such as radiation. Here, we evaluated the dependence of pancreatic cancer stem cells (PCSCs) on this non-canonical glutamine metabolism pathway and researched whether inhibiting this pathway can enhance radiosensitivity of PCSCs. We showed that glutamine deprivation significantly inhibited self-renewal, decreased expression of stemness-related genes, increased intracellular ROS, and induced apoptosis in PCSCs. These effects were countered by oxaloacetate, but not α-ketoglutarate. Knockdown of glutamic-oxaloacetic transaminase dramatically impaired PCSCs properties, while glutamate dehydrogenase knockdown had a limited effect, suggesting a dependence of PCSCs on non-canonical glutamine metabolism. Additionally, glutamine deprivation significantly increased radiation-induced ROS and sensitized PCSCs to fractionated radiation. Moreover, transaminase inhibitors effectively enhanced ROS generation, promoted radiation sensitivity, and attenuated tumor growth in nude mice following radiation exposure. Our findings reveal that inhibiting the non-canonical pathway of glutamine metabolism enhances the PCSC radiosensitivity and may be an effective adjunct in cancer radiotherapy. PMID:26439804

  20. SIRT1 controls cell proliferation by regulating contact inhibition.

    PubMed

    Cho, Elizabeth H; Dai, Yan

    2016-09-16

    Contact inhibition keeps cell proliferation in check and serves as a built-in protection against cancer development by arresting cell division upon cell-cell contact. Yet the complete mechanism behind this anti-cancer process remains largely unclear. Here we present SIRT1 as a novel regulator of contact inhibition. SIRT1 performs a wide variety of functions in biological processes, but its involvement in contact inhibition has not been explored to date. We used NIH3T3 cells, which are sensitive to contact inhibition, and H460 and DU145 cancer cells, which lack contact inhibition, to investigate the relationship between SIRT1 and contact inhibition. We show that SIRT1 overexpression in NIH3T3 cells overcomes contact inhibition while SIRT1 knockdown in cancer cells restores their lost contact inhibition. Moreover, we demonstrate that p27 protein expression is controlled by SIRT1 in contact inhibition. Overall, our findings underline the critical role of SIRT1 in contact inhibition and suggest SIRT1 inhibition as a potential strategy to suppress cancer cell growth by restoring contact inhibition.

  1. Molecular mechanisms that control endothelial cell contacts.

    PubMed

    Vestweber, D

    2000-02-01

    Endothelial cell contacts control the permeability of the blood vessel wall. This allows the endothelium to form a barrier for solutes, macromolecules, and leukocytes between the vessel lumen and the interstitial space. Loss of this barrier function in pathophysiological situations can lead to extracellular oedema. The ability of leukocytes to enter tissue at sites of inflammation is dependent on molecular mechanisms that allow leukocytes to adhere to the endothelium and to migrate through the endothelial cell layer and the underlying basal lamina. It is a commonly accepted working hypothesis that inter-endothelial cell contacts are actively opened and closed during this process. Angiogenesis is another important process that requires well-controlled regulation of inter-endothelial cell contacts. The formation of new blood vessels by sprouting from pre-existing vessels depends on the loosening of established endothelial cell contacts and the migration of endothelial cells that form the outgrowing sprouts. This review focuses on the molecular composition of endothelial cell surface proteins and proteins of the cytoskeletal undercoat of the plasma membrane at sites of inter-endothelial cell contacts and discusses the current knowledge about the potential role of such molecules in the regulation of endothelial cell contacts. PMID:10685062

  2. Evaluation of an α synuclein sensitized dendritic cell based vaccine in a transgenic mouse model of Parkinson disease.

    PubMed

    Ugen, Kenneth E; Lin, Xiaoyang; Bai, Ge; Liang, Zhanhua; Cai, Jianfeng; Li, Kunyun; Song, Shijie; Cao, Chuanhai; Sanchez-Ramos, Juan

    2015-01-01

    In order to develop a cell-based vaccine against the Parkinson disease (PD) associated protein α-synuclein (α-Syn) 3 peptides were synthesized based upon predicted B cell epitopes within the full length α-Syn protein sequence. These peptide fragments as well as the full length recombinant human α-Syn (rh- α-Syn) protein were used to sensitize mouse bone marrow-derived dendritic cells (DC) ex vivo, followed by intravenous delivery of these sensitized DCs into transgenic (Tg) mice expressing the human A53T variant of α-Syn. ELISA analysis and testing of behavioral locomotor function by rotometry were performed on all mice after the 5th vaccination as well as just prior to euthanasia. The results indicated that vaccination with peptide sensitized DCs (PSDC) as well as DCs sensitized by rh-α-Syn induced specific anti-α-Syn antibodies in all immunized mice. In terms of rotometry performance, a measure of locomotor activity correlated to brain dopamine levels, mice vaccinated with PSDC or rh- α-Syn sensitized DCs performed significantly better than non-vaccinated Tg control mice during the final assessment (i.e. at 17 months of age) before euthanasia. As well, measurement of levels of brain IL-1α, a cytokine hypothesized to be associated with neuroinflammation, demonstrated that this proinflammatory molecule was significantly reduced in the PSDC and rh- α-Syn sensitized DC vaccinated mice compared to the non-vaccinated Tg control group. Overall, α-Syn antigen-sensitized DC vaccination was effective in generating specific anti- α-Syn antibodies and improved locomotor function without eliciting an apparent general inflammatory response, indicating that this strategy may be a safe and effective treatment for PD.

  3. "Spider"-shaped porphyrins with conjugated pyridyl anchoring groups as efficient sensitizers for dye-sensitized solar cells.

    PubMed

    Stangel, Christina; Bagaki, Anthi; Angaridis, Panagiotis A; Charalambidis, Georgios; Sharma, Ganesh D; Coutsolelos, Athanasios G

    2014-11-17

    Two novel "spider-shaped" porphyrins, meso-tetraaryl-substituted 1PV-Por and zinc-metalated 1PV-Zn-Por, bearing four oligo(p-phenylenevinylene) (oPPV) pyridyl groups with long dodecyloxy chains on the phenyl groups, have been synthesized. The presence of four pyridyl groups in both porphyrins, which allow them to act as anchoring groups upon coordination to various Lewis acid sites, the conjugated oPPV bridges, which offer the possibility of electronic communication between the porphyrin core and the pyridyl groups, and the dodecyloxy groups, which offer the advantage of high solubility in a variety of organic solvents of different polarities and could prevent porphyrin aggregation, renders porphyrins 1PV-Por and 1PV-Zn-Por very promising sensitizers for dye-sensitized solar cells (DSSCs). Photophysical measurements, together with electrochemistry experiments and density functional theory calculations, suggest that both porphyrins have frontier molecular orbital energy levels that favor electron injection and dye regeneration in DSSCs. Solar cells sensitized by 1PV-Por and 1PV-Zn-Por were fabricated, and it was found that they show power conversion efficiencies (PCEs) of 3.28 and 5.12%, respectively. Photovoltaic measurements (J-V curves) together with incident photon-to-electron conversion efficiency spectra of the two cells reveal that the higher PCE value of the DSSC based on 1PV-Zn-Por is ascribed to higher short-circuit current (Jsc), open-circuit voltage (Voc), and dye loading values. Emission spectra and electrochemistry experiments suggest a greater driving force for injection of the photogenerated electrons into the TiO2 conduction band for 1PV-Zn-Por rather than its free-base analogue. Furthermore, electrochemical impedance spectroscopy measurements prove that the utilization of 1PV-Zn-Por as a sensitizer offers a high charge recombination resistance and, therefore, leads to a longer electron lifetime.

  4. Role of calreticulin in the sensitivity of myocardiac H9c2 cells to oxidative stress caused by hydrogen peroxide.

    PubMed

    Ihara, Yoshito; Urata, Yoshishige; Goto, Shinji; Kondo, Takahito

    2006-01-01

    Calreticulin (CRT), a Ca2+-binding molecular chaperone in the endoplasmic reticulum, plays a vital role in cardiac physiology and pathology. Oxidative stress is a main cause of myocardiac apoptosis in the ischemic heart, but the function of CRT under oxidative stress is not fully understood. In the present study, the effect of overexpression of CRT on susceptibility to apoptosis under oxidative stress was examined using myocardiac H9c2 cells transfected with the CRT gene. Under oxidative stress due to H2O2, the CRT-overexpressing cells were highly susceptible to apoptosis compared with controls. In the overexpressing cells, the levels of cytoplasmic free Ca2+ ([Ca2+]i) were significantly increased by H2O2, whereas in controls, only a slight increase was observed. The H2O2-induced apoptosis was enhanced by the increase in [Ca2+]i caused by thapsigargin in control cells but was suppressed by BAPTA-AM, a cell-permeable Ca2+ chelator in the CRT-overexpressing cells, indicating the importance of the level of [Ca2+]i in the sensitivity to H2O2-induced apoptosis. Suppression of CRT by the introduction of the antisense cDNA of CRT enhanced cytoprotection against oxidative stress compared with controls. Furthermore, we found that the levels of activity of calpain and caspase-12 were elevated through the regulation of [Ca2+]i in the CRT-overexpressing cells treated with H2O2 compared with controls. Thus we conclude that the level of CRT regulates the sensitivity to apoptosis under oxidative stress due to H2O2 through a change in Ca2+ homeostasis and the regulation of the Ca2+-calpain-caspase-12 pathway in myocardiac cells. PMID:16135540

  5. Role of calreticulin in the sensitivity of myocardiac H9c2 cells to oxidative stress caused by hydrogen peroxide.

    PubMed

    Ihara, Yoshito; Urata, Yoshishige; Goto, Shinji; Kondo, Takahito

    2006-01-01

    Calreticulin (CRT), a Ca2+-binding molecular chaperone in the endoplasmic reticulum, plays a vital role in cardiac physiology and pathology. Oxidative stress is a main cause of myocardiac apoptosis in the ischemic heart, but the function of CRT under oxidative stress is not fully understood. In the present study, the effect of overexpression of CRT on susceptibility to apoptosis under oxidative stress was examined using myocardiac H9c2 cells transfected with the CRT gene. Under oxidative stress due to H2O2, the CRT-overexpressing cells were highly susceptible to apoptosis compared with controls. In the overexpressing cells, the levels of cytoplasmic free Ca2+ ([Ca2+]i) were significantly increased by H2O2, whereas in controls, only a slight increase was observed. The H2O2-induced apoptosis was enhanced by the increase in [Ca2+]i caused by thapsigargin in control cells but was suppressed by BAPTA-AM, a cell-permeable Ca2+ chelator in the CRT-overexpressing cells, indicating the importance of the level of [Ca2+]i in the sensitivity to H2O2-induced apoptosis. Suppression of CRT by the introduction of the antisense cDNA of CRT enhanced cytoprotection against oxidative stress compared with controls. Furthermore, we found that the levels of activity of calpain and caspase-12 were elevated through the regulation of [Ca2+]i in the CRT-overexpressing cells treated with H2O2 compared with controls. Thus we conclude that the level of CRT regulates the sensitivity to apoptosis under oxidative stress due to H2O2 through a change in Ca2+ homeostasis and the regulation of the Ca2+-calpain-caspase-12 pathway in myocardiac cells.

  6. Extracellular Calcium Has Multiple Targets to Control Cell Proliferation.

    PubMed

    Capiod, Thierry

    2016-01-01

    Calcium channels and the two G-protein coupled receptors sensing extracellular calcium, calcium-sensing receptor (CaSR) and GPRC6a, are the two main means by which extracellular calcium can signal to cells and regulate many cellular processes including cell proliferation, migration and invasion of tumoral cells. Many intracellular signaling pathways are sensitive to cytosolic calcium rises and conversely intracellular signaling pathways can modulate calcium channel expression and activity. Calcium channels are undoubtedly involved in the former while the CaSR and GPRC6a are most likely to interfere with the latter. As for neurotransmitters, calcium ions use plasma membrane channels and GPCR to trigger cytosolic free calcium concentration rises and intracellular signaling and regulatory pathways activation. Calcium sensing GPCR, CaSR and GPRC6a, allow a supplemental degree of control and as for metabotropic receptors, they not only modulate calcium channel expression but they may also control calcium-dependent K+ channels. The multiplicity of intracellular signaling pathways involved, their sensitivity to local and global intracellular calcium increase and to CaSR and GPRC6a stimulation, the presence of membrane signalplex, all this confers the cells the plasticity they need to convert the effects of extracellular calcium into complex physiological responses and therefore determine their fate.

  7. Extracellular Calcium Has Multiple Targets to Control Cell Proliferation.

    PubMed

    Capiod, Thierry

    2016-01-01

    Calcium channels and the two G-protein coupled receptors sensing extracellular calcium, calcium-sensing receptor (CaSR) and GPRC6a, are the two main means by which extracellular calcium can signal to cells and regulate many cellular processes including cell proliferation, migration and invasion of tumoral cells. Many intracellular signaling pathways are sensitive to cytosolic calcium rises and conversely intracellular signaling pathways can modulate calcium channel expression and activity. Calcium channels are undoubtedly involved in the former while the CaSR and GPRC6a are most likely to interfere with the latter. As for neurotransmitters, calcium ions use plasma membrane channels and GPCR to trigger cytosolic free calcium concentration rises and intracellular signaling and regulatory pathways activation. Calcium sensing GPCR, CaSR and GPRC6a, allow a supplemental degree of control and as for metabotropic receptors, they not only modulate calcium channel expression but they may also control calcium-dependent K+ channels. The multiplicity of intracellular signaling pathways involved, their sensitivity to local and global intracellular calcium increase and to CaSR and GPRC6a stimulation, the presence of membrane signalplex, all this confers the cells the plasticity they need to convert the effects of extracellular calcium into complex physiological responses and therefore determine their fate. PMID:27161228

  8. The isolated anatase for dye sensitized solar cell

    SciTech Connect

    Ilmi, Irfan; Kartin, Indriana; Suyanta; Ohtani, Bunsho; Wang, Kunlei

    2015-09-30

    The isolation of crystallite anatase from commercial TiO{sub 2} P25 Degussa was investigated. The aim of this research was to study of isolated anatase based DSSC as an effort to develop industrial DSSC. The crystal phase, crystallite size and crystal shape both of original P25 and isolated anatase were characterized by XRD and TEM. By observing DSSC parameters such as FF, Jsc and Voc resulted in cell test, the efficiency of samples based DSSC was known. The isolation of anatase crystal was done by dissolving P25 in ammonia catalyzed hydrogen peroxide solution for 15 hours followed by washing and drying. DSSC cell performance was evaluated by applying the isolated anantase and original P25 as photoanode in the Gratzel cell system. The observation of cell efficiency was measured under 100 mW /cm{sup 2} with active area 1.5 cm{sup 2}. X-ray diffraction pattern showed obviously that no rutile contaminant in produced isolated anatase. TEM image shows typical anatase crystal with the particle size 21 nm. Surface area measurement exhibits that surface area of isolated anatase was 64.7m{sup 2}/g. I-V measurement showed that the efficiency of anatase based cell and P25 based cell is 0.79% and 0.51% respectively.

  9. Pro-active optimal control for semi-active vehicle suspension based on sensitivity updates

    NASA Astrophysics Data System (ADS)

    Michael, Johannes; Gerdts, Matthias

    2015-12-01

    This article suggests a strategy to control semi-active suspensions of vehicles in a pro-active way to adapt to future road profiles. The control strategy aims to maximise comfort while maintaining good handling properties. It employs suitably defined optimal control problems in combination with a parametric sensitivity analysis. The optimal control techniques are used to optimise the time-dependent damper coefficients in an electro-rheological damper for given nominal road profiles. The parametric sensitivity analysis is used to adapt the computed nominal optimal controls to perturbed road profiles in real time. The method is particularly useful for events with a low excitation frequency such as ramps, bumps, or potholes. For high-frequency excitations standard controllers are preferable; so we propose a switched open-closed-loop controller design. Various examples demonstrate the performance of the approach.

  10. Dasatinib enhances cisplatin sensitivity in human esophageal squamous cell carcinoma (ESCC) cells via suppression of PI3K/AKT and Stat3 pathways.

    PubMed

    Chen, Jie; Lan, Tian; Zhang, Weimin; Dong, Lijia; Kang, Nan; Fu, Ming; Liu, Bing; Liu, Kangtai; Zhang, Cuixiang; Hou, Jincai; Zhan, Qimin

    2015-06-01

    The clinical efficacy of cisplatin in esophageal squamous cell carcinoma (ESCC) treatment remains undesirable. Src, a non-receptor tyrosine kinase involved in multiple fields of tumorigenesis, recently has been indicated as a promising therapeutic target in the treatment of solid tumors including ESCC. However, whether inhibition of Src activity can increase cisplatin efficacy in ESCC cells remains unknown. The present study found that inhibition of Src by its inhibitor-dasatinib sensitized ESCC cells to cisplatin in vitro. Our data also suggest a likely mechanism for this synergy that dasatinib reduces expression of critical oncogenic members of the signaling pathways, such as AKT or Stat3, and cisplatin-resistant molecules, such as ERCC1 and BRCA1, under the control of Src. Furthermore, dasatinib could sensitize ESCC cells to another platin-based agent, carboplatin. Therefore, this study provides a potential target for improving cisplatin efficacy in ESCC therapy.

  11. Controlled regular locomotion of algae cell microrobots.

    PubMed

    Xie, Shuangxi; Jiao, Niandong; Tung, Steve; Liu, Lianqing

    2016-06-01

    Algae cells can be considered as microrobots from the perspective of engineering. These organisms not only have a strong reproductive ability but can also sense the environment, harvest energy from the surroundings, and swim very efficiently, accommodating all these functions in a body of size on the order of dozens of micrometers. An interesting topic with respect to random swimming motions of algae cells in a liquid is how to precisely control them as microrobots such that they swim according to manually set routes. This study developed an ingenious method to steer swimming cells based on the phototaxis. The method used a varying light signal to direct the motion of the cells. The swimming trajectory, speed, and force of algae cells were analyzed in detail. Then the algae cell could be controlled to swim back and forth, and traverse a crossroad as a microrobot obeying specific traffic rules. Furthermore, their motions along arbitrarily set trajectories such as zigzag, and triangle were realized successfully under optical control. Robotize algae cells can be used to precisely transport and deliver cargo such as drug particles in microfluidic chip for biomedical treatment and pharmacodynamic analysis. The study findings are expected to bring significant breakthrough in biological drives and new biomedical applications.

  12. Correlation of contact sensitizer potency with T cell frequency and TCR repertoire diversity.

    PubMed

    Esser, Philipp R; Kimber, Ian; Martin, Stefan F

    2014-01-01

    Allergic contact dermatitis is a T cell-mediated skin disease. Many hundreds of organic chemicals and some metal ions are contact sensitizers. They induce an innate inflammatory immune response in the skin that results in the priming of contact sensitizer-specific T cells by dendritic cells in the draining lymph nodes. The factors that determine the strength of this T cell response and thereby define the potency of a contact sensitizer are largely unknown. This chapter highlights different variables such as precursor frequency of antigen-specific T cells, possible bystander activation, and T cell receptor diversity or avidity of the TCR/peptide-MHC interactions, which might impact the quality and strength of T cell responses to contact sensitizers. In addition, different methods available to determine both the frequency of antigen-specific T cells and T cell receptor repertoires are discussed. Identification of the factors determining potency may allow for the development of suitable in vitro assays for potency assessment of contact sensitizers.

  13. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway.

    PubMed

    You, Y; Wen, R; Pathak, R; Li, A; Li, W; St Clair, D; Hauer-Jensen, M; Zhou, D; Liang, Y

    2014-10-23

    Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy.

  14. Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis

    NASA Technical Reports Server (NTRS)

    Ingber, D. E.; Prusty, D.; Sun, Z.; Betensky, H.; Wang, N.

    1995-01-01

    Capillary endothelial cells can be switched between growth and differentiation by altering cell-extracellular matrix interactions and thereby, modulating cell shape. Studies were carried out to determine when cell shape exerts its growth-regulatory influence during cell cycle progression and to explore the role of cytoskeletal structure and mechanics in this control mechanism. When G0-synchronized cells were cultured in basic fibroblast growth factor (FGF)-containing defined medium on dishes coated with increasing densities of fibronectin or a synthetic integrin ligand (RGD-containing peptide), cell spreading, nuclear extension, and DNA synthesis all increased in parallel. To determine the minimum time cells must be adherent and spread on extracellular matrix (ECM) to gain entry into S phase, cells were removed with trypsin or induced to retract using cytochalasin D at different times after plating. Both approaches revealed that cells must remain extended for approximately 12-15 h and hence, most of G1, in order to enter S phase. After this restriction point was passed, normally 'anchorage-dependent' endothelial cells turned on DNA synthesis even when round and in suspension. The importance of actin-containing microfilaments in shape-dependent growth control was confirmed by culturing cells in the presence of cytochalasin D (25-1000 ng ml-1): dose-dependent inhibition of cell spreading, nuclear extension, and DNA synthesis resulted. In contrast, induction of microtubule disassembly using nocodazole had little effect on cell or nuclear spreading and only partially inhibited DNA synthesis. Interestingly, combination of nocodazole with a suboptimal dose of cytochalasin D (100 ng ml-1) resulted in potent inhibition of both spreading and growth, suggesting that microtubules are redundant structural elements which can provide critical load-bearing functions when microfilaments are partially compromised. Similar synergism between nocodazole and cytochalasin D was observed

  15. Ride quality sensitivity to SAS control law and to handling quality variations

    NASA Technical Reports Server (NTRS)

    Roberts, P. A.; Schmidt, D. K.; Swaim, R. L.

    1976-01-01

    The RQ trends which large flexible aircraft exhibit under various parameterizations of control laws and handling qualities are discussed. A summary of the assumptions and solution technique, a control law parameterization review, a discussion of ride sensitivity to handling qualities, and the RQ effects generated by implementing relaxed static stability configurations are included.

  16. Rho GTPases, oxidation, and cell redox control

    PubMed Central

    Hobbs, G Aaron; Zhou, Bingying; Cox, Adrienne D; Campbell, Sharon L

    2014-01-01

    While numerous studies support regulation of Ras GTPases by reactive oxygen and nitrogen species, the Rho subfamily has received considerably less attention. Over the last few years, increasing evidence is emerging that supports the redox sensitivity of Rho GTPases. Moreover, as Rho GTPases regulate the cellular redox state by controlling enzymes that generate and convert reactive oxygen and nitrogen species, redox feedback loops likely exist. Here, we provide an overview of cellular oxidants, Rho GTPases, and their inter-dependence. PMID:24809833

  17. Light sensitive memristor with bi-directional and wavelength-dependent conductance control

    NASA Astrophysics Data System (ADS)

    Maier, P.; Hartmann, F.; Rebello Sousa Dias, M.; Emmerling, M.; Schneider, C.; Castelano, L. K.; Kamp, M.; Marques, G. E.; Lopez-Richard, V.; Worschech, L.; Höfling, S.

    2016-07-01

    We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

  18. Theoretica Study of Asymmetric Double D-π-A Organic Sensitizers for Efficient Dye-Sensitized Solar Cells.

    PubMed

    Kwon, Dong Yuel; Lee, Gun Hyung; Kim, Young Sik

    2015-03-01

    Three novel dye sensitizers that were based on asymmetric double D-π-A chains with phenoxazine (POZ) and diphenylamine (DPA) as electron donors and cyanoacetic acid (CA) and 2-(1,1- dicyanomethylene) rhodanine (RD) as electron acceptors (DCPR, DRPC, DRPR) were designed, theoretically investigated, and compared with the reference dye based on asymmetric double D-π-A chains (DCPC). Using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations, we gained insight into the factors responsible for the photovoltaic properties of the dye sensitizers. Due to the different HOMO levels of each donor and the different LUMO levels of each acceptor, the absorption spectrum of each dye showed different shapes. Among the dyes, DRPR showed a broader and more bathochromically shifted absorption band than the other dies. It also showed a higher molar extinction coefficient than that of the reference dye (DCPC). This work suggests optimizing the chain of electron donors and acceptors in dye sensitizers based on asymmetric double D-π-A chains would produce good photovoltaic properties for dye-sensitized solar cells (DSSCs).

  19. Enhancing dye-sensitized solar cell performances by molecular engineering: highly efficient π-extended organic sensitizers.

    PubMed

    Grisorio, Roberto; De Marco, Luisa; Agosta, Rita; Iacobellis, Rosabianca; Giannuzzi, Roberto; Manca, Michele; Mastrorilli, Piero; Gigli, Giuseppe; Suranna, Gian Paolo

    2014-09-01

    This study deals with the synthesis and characterization of two π-extended organic sensitizers (G1 and G2) for applications in dye-sensitized solar cells. The materials are designed with a D-A-π-A structure constituted by i) a triarylamine group as the donor part, ii) a dithienyl-benzothiadiazole chromophore followed by iii) a further ethynylene-thiophene (G1) or ethynylene-benzene (G2) π-spacer and iv) a cyano-acrylic moiety as acceptor and anchoring part. An unusual structural extension of the π-bridge characterizes these structures. The so-configured sensitizers exhibit a broad absorption profile, the origin of which is supported by density functional theory. The absence of hypsochromic shifts as a consequence of deprotonation as well as notable optical and electrochemical stabilities are also observed. Concerning the performances in devices, electrochemical impedance spectroscopy indicates that the structural modification of the π-spacer mainly increases the electron lifetime of G2 with respect to G1. In devices, this feature translates into a superior power conversion efficiency of G2, reaching 8.1%. These results are comparable to those recorded for N719 and are higher with respect to literature congeners, supporting further structural engineering of the π-bridge extension in the search for better performing π-extended organic sensitizers.

  20. Molecularly Engineered Ru(II) Sensitizers Compatible with Cobalt(II/III) Redox Mediators for Dye-Sensitized Solar Cells.

    PubMed

    Wu, Kuan-Lin; Huckaba, Aron J; Clifford, John N; Yang, Ya-Wen; Yella, Aswani; Palomares, Emilio; Grätzel, Michael; Chi, Yun; Nazeeruddin, Mohammad Khaja

    2016-08-01

    Thiocyanate-free isoquinazolylpyrazolate Ru(II) complexes were synthesized and applied as sensitizers in dye-sensitized solar cells (DSCs). Unlike most other successful Ru sensitizers, Co-based electrolytes were used, and resulting record efficiency of 9.53% was obtained under simulated sunlight with an intensity of 100 mW cm(-2). Specifically, dye 51-57dht.1 and an electrolyte based on Co(phen)3 led to measurement of a JSC of 13.89 mA cm(-2), VOC of 900 mV, and FF of 0.762 to yield 9.53% efficiency. The improved device performances were achieved by the inclusion of 2-hexylthiophene units onto the isoquinoline subunits, in addition to lengthening the perfluoroalkyl chain on the pyrazolate chelating group, which worked to increase light absorption and decrease recombination effects when using the Co-based electrolyte. As this study shows, Ru(II) sensitizers bearing sterically demanding ligands can allow successful utilization of important Co electrolytes and high performance. PMID:27420188

  1. Design of Sensitivity Function of Multi-Rate VCM Control System

    NASA Astrophysics Data System (ADS)

    Kisaka, Masashi

    The method for designing the sensitivity function of a multiple-input single-output servo system is proposed. The method does not require weight or a weight function unlike linear quadratic (LQ) or H∞ design. First, a controller candidate is derived by taking into consideration the specification of robustness of the plant system. Then, the sensitivity function is derived from the gain specification of the sensitivity function. As the design of a multi-rate controller can be shown to be equivalent to the multiple-input single-output system, the method is employed to design the multi-rate VCM position control system. The multi-rate controller is designed such that at frequencies higher than the Nyquist frequency, the desired robustness is achieved.

  2. Quinazolinedione SIRT6 inhibitors sensitize cancer cells to chemotherapeutics.

    PubMed

    Sociali, Giovanna; Galeno, Lauretta; Parenti, Marco Daniele; Grozio, Alessia; Bauer, Inga; Passalacqua, Mario; Boero, Silvia; Donadini, Alessandra; Millo, Enrico; Bellotti, Marta; Sturla, Laura; Damonte, Patrizia; Puddu, Alessandra; Ferroni, Claudia; Varchi, Greta; Franceschi, Claudio; Ballestrero, Alberto; Poggi, Alessandro; Bruzzone, Santina; Nencioni, Alessio; Del Rio, Alberto

    2015-09-18

    The NAD(+)-dependent sirtuin SIRT6 is highly expressed in human breast, prostate, and skin cancer where it mediates resistance to cytotoxic agents and prevents differentiation. Thus, SIRT6 is an attractive target for the development of new anticancer agents to be used alone or in combination with chemo- or radiotherapy. Here we report on the identification of novel quinazolinedione compounds with inhibitory activity on SIRT6. As predicted based on SIRT6's biological functions, the identified new SIRT6 inhibitors increase histone H3 lysine 9 acetylation, reduce TNF-α production and increase glucose uptake in cultured cells. In addition, these compounds exacerbate DNA damage and cell death in response to the PARP inhibitor olaparib in BRCA2-deficient Capan-1 cells and cooperate with gemcitabine to the killing of pancreatic cancer cells. In conclusion, new SIRT6 inhibitors with a quinazolinedione-based structure have been identified which are active in cells and could potentially find applications in cancer treatment.

  3. Peptides whose uptake by cells is controllable

    DOEpatents

    Jiang, Tao; Tsien, Roger Y

    2014-02-04

    A generic structure for the peptides of the present invention includes A-X-B-C, where C is a cargo moiety, the B portion includes basic amino acids, X is a cleavable linker sequence, and the A portion includes acidic amino acids. The intact structure is not significantly taken up by cells; however, upon extracellular cleavage of X, the B-C portion is taken up, delivering the cargo to targeted cells. Cargo may be, for example, a contrast agent for diagnostic imaging, a chemotherapeutic drug, or a radiation-sensitizer for therapy. Cleavage of X allows separation of A from B, unmasking the normal ability of the basic amino acids in B to drag cargo C into cells near the cleavage event. X is cleaved extracellularly, preferably under physiological conditions. D-amino acids are preferred for the A and B portions, to minimize immunogenicity and nonspecific cleavage by background peptidases or proteases.

  4. Peptides whose uptake by cells is controllable

    DOEpatents

    Jiang, Tao; Tsien, Roger Y.

    2012-02-07

    A generic structure for the peptides of the present invention includes A-X-B-C, where C is a cargo moiety, the B portion includes basic amino acids, X is a cleavable linker sequence, and the A portion includes acidic amino acids. The intact structure is not significantly taken up by cells; however, upon extracellular cleavage of X, the B-C portion is taken up, delivering the cargo to targeted cells. Cargo may be, for example, a contrast agent for diagnostic imaging, a chemotherapeutic drug, or a radiation-sensitizer for therapy. Cleavage of X allows separation of A from B, unmasking the normal ability of the basic amino acids in B to drag cargo C into cells near the cleavage event. X is cleaved extracellularly, preferably under physiological conditions. D-amino acids are preferred for the A and B portions, to minimize immunogenicity and nonspecific cleavage by background peptidases or proteases.

  5. Peptides whose uptake by cells is controllable

    DOEpatents

    Jiang, Tao; Tsien, Roger Y.

    2008-10-07

    A generic structure for the peptides of the present invention includes A-X-B-C, where C is a cargo moiety, the B portion includes basic amino acids, X is a cleavable linker sequence, and the A portion includes acidic amino acids. The intact structure is not significantly taken up by cells; however, upon extracellular cleavage of X, the B-C portion is taken up, delivering the cargo to targeted cells. Cargo may be, for example, a contrast agent for diagnostic imaging, a chemotherapeutic drug, or a radiation-sensitizer for therapy. Cleavage of X allows separation of A from B, unmasking the normal ability of the basic amino acids in B to drag cargo C into cells near the cleavage event. X is cleaved extracellularly, preferably under physiological conditions. D-amino acids are preferred for the A and B portions, to minimize immunogenicity and nonspecific cleavage by background peptidases or proteases.

  6. Geometric control of myogenic cell fate

    PubMed Central

    de Juan-Pardo, Elena M; Hoang, Mike Bao-Trong; Conboy, Irina M

    2006-01-01

    This work combines expertise in stem cell biology and bioengineering to define the system for geometric control of proliferation and differentiation of myogenic progenitor cells. We have created an artificial niche of myogenic progenitor cells, namely, modified extracellular matrix (ECM) substrates with spatially embedded growth or differentiation factors (GF, DF) that predictably direct muscle cell fate in a geometric pattern. Embedded GF and DF signal progenitor cells from specifically defined areas on the ECM successfully competed against culture media for myogenic cell fate determination at a clearly defined boundary. Differentiation of myoblasts into myotubes is induced in growth-promoting medium, myotube formation is delayed in differentiation-promoting medium, and myogenic cells, at different stages of proliferation and differentiation, can be induced to coexist adjacently in identical culture media. This method can be used to identify molecular interactions between cells in different stages of myogenic differentiation, which are likely to be important determinants of tissue repair. The designed ECM niches can be further developed into a vehicle for transplantation of myogenic progenitor cells maintaining their regenerative potential. Additionally, this work may also serve as a general model to engineer synthetic cellular niches to harness the regenerative potential of organ stem cells. PMID:17722537

  7. Aggregated TiO2 Based Nanotubes for Dye Sensitized Solar Cells

    SciTech Connect

    Nie, Zimin; Zhou, Xiaoyuan; Zhang, Qifeng; Cao, Guozhong; Liu, Jun

    2013-11-01

    One-dimensional (1D) semiconducting oxides have attracted great attention for dye sensitized solar cells (DSCs), but the overall performance is still quite limited as compared to TiO2 nanocrystalline DSCs. Here, we report the synthesis of aggregated TiO2 based nanotubes with controlled morphologies and crystalline structures to obtain an overall power conversion efficiency of 9.9% using conventional dye without any additional chemical treatment steps. The high efficiency is attributed to the unique aggregate structure for light harvesting, optimized high surface area, and good crystallinity of the nanotube aggregates obtained through proper thermal annealing. This study demonstrates that high efficiency DSCs can be obtained with 1D nanomaterials, and provides lessons on the importance of optimizing both the nanocrystalline structure and the overall microscale morphology.

  8. Laurus nobilis L. Seed Extract Reveals Collateral Sensitivity in Multidrug-Resistant P-Glycoprotein-Expressing Tumor Cells.

    PubMed

    Saab, Antoine M; Guerrini, Alessandra; Zeino, Maen; Wiench, Benjamin; Rossi, Damiano; Gambari, Roberto; Sacchetti, Gianni; Greten, Henry Johannes; Efferth, Thomas

    2015-01-01

    The frequent failure of standard cancer chemotherapy requires the development of novel drugs capable of killing otherwise drug-resistant tumors. Here, we have investigated a chloroform extract of Laurus nobilis seeds. Fatty acids and 23 constituents of the volatile fraction were identified by gas chromotography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS), in good agreement with (1)H NMR (nuclear magnetic resonance) spectrum. Multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells were hypersensitive (collaterally sensitive) toward this extract compared to drug-sensitive CCRF-CEM cells, whereas CEM/ADR5000 cells were 2586-fold resistant to doxorubicin as control drug. Collateral sensitivity was verified by measurement of apoptotic cells by flow cytometry. The log10IC50 values of 3 compounds in the extract (limonene, eucalyptol, oleic acid) did not correlate with mRNA expression of the P-glycoprotein-coding ABCB1/MDR1 gene and accumulation of the P-glycoprotein substrate rhodamine in the NCI panel of tumor cell lines. A microarray-based profile of 20 genes predicted resistance to doxorubicin and 7 other anticancer drugs involved in the multidrug resistance phenotype but not to limonene, eucalyptol and oleic acid. In conclusion, our results show that Laurus nobilis seed extract is suitable to kill multidrug-resistant P-glycoprotein expressing tumor cells.

  9. Review on nanostructured semiconductors for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Prakash, T.

    2012-06-01

    Nanostructured semiconductors with different morphologies are used widely in various applications in order to enhance their technological advancements compared with the bulk sample. This flourishing nanoscience field has enabled rapid developments that have created numerous opportunities for scienctific advancements with various devices. Considering large environmental impacts such as global warming, problems of nuclear waste storage and nuclear accidents, there is an urgent need for environmentally sustainable energy technologies such as solar cells and fuel cells. In the present paper, the role of nanostructured semiconductors in dyesensitized solar cells (DSSCs) is reviewed entensively. The review discusses the present developmental prospects of DSSCs and the problems associated with its layer materials and propose a method of overcoming these problems.

  10. Dendritic cells and skin sensitization: Biological roles and uses in hazard identification

    SciTech Connect

    Ryan, Cindy A.; Kimber, Ian; Basketter, David A.; Pallardy, Marc; Gildea, Lucy A.; Gerberick, G. Frank . E-mail: gerberick.gf@pg.com

    2007-06-15

    Recent advances have been made in our understanding of the roles played by cutaneous dendritic cells (DCs) in the induction of contact allergy. A number of associated changes in epidermal Langerhans cell phenotype and function required for effective skin sensitization are providing the foundations for the development of cellular assays (using DC and DC-like cells) for skin sensitization hazard identification. These alternative approaches to the identification and characterization of skin sensitizing chemicals were the focus of a Workshop entitled 'Dendritic Cells and Skin Sensitization: Biological Roles and Uses in Hazard Identification' that was given at the annual Society of Toxicology meeting held March 6-9, 2006 in San Diego, California. This paper reports information that was presented during the Workshop.

  11. Electrical characterization of dye sensitized nano solar cell using natural pomegranate juice as photosensitizer

    NASA Astrophysics Data System (ADS)

    Adithi, U.; Thomas, Sara; Uma, V.; Pradeep, N.

    2013-02-01

    This paper shows Electrical characterization of Dye Sensitized Solar Cell using natural dye, extracted from the pomegranate as a photo sensitizer and ZnO nanoparticles as semiconductor. The constituents of fabricated dye sensitized solar cell were working electrode, dye, electrolyte and counter electrode. ZnO nanoparticles were synthesized and used as semiconductor in working electrode. Carbon soot was used as counter electrode. The resistance of ZnO film on ITO film was found out. There was an increase in the resistance of the film and film changes from conducting to semiconducting. Photovoltaic parameters of the fabricated cell like Short circuit current, open circuit voltage, Fill factor and Efficiency were found out. This paper shows that usage of natural dyes like pomegranate juice as sensitizer enables faster and simpler production of cheaper and environmental friendly solar cell.

  12. Characterization of screen-printed dye-sensitized nanocrystalline TiO2 solar cells

    NASA Astrophysics Data System (ADS)

    Gupta, Tapan K.; Cirignano, Leonard J.; Shah, Kanai S.; Moy, Larry P.; Kelly, David J.; Squillante, Michael R.; Entine, Gerald; Smestad, Greg P.

    1999-10-01

    Titanium dioxide (TiO2) films have been deposited on SnO2 coated glass substrates by screen-printing. Film morphology and structure have been characterized by scanning electron microscopy, x-ray diffraction and BET analysis. Dye-sensitized TiO2 photoelectrochemical cells have been assembled and characterized. Cells sensitized with anthocyanin and a ruthenium complex have been investigated. A 0.77 cm2 ruthenium dye sensitized cell with 6.1% power conversion efficiency under Air Mass (AM1.5) conditions was obtained. Results obtained with a pure anthocyanin dye and dye extracted from blackberries were compared. Finally, a natural gel was found to improve the stability of anthocyanin sensitized cells.

  13. Spatial phase sensitivity of complex cells in primary visual cortex depends on stimulus contrast.

    PubMed

    Meffin, H; Hietanen, M A; Cloherty, S L; Ibbotson, M R

    2015-12-01

    Neurons in primary visual cortex are classified as simple, which are phase sensitive, or complex, which are significantly less phase sensitive. Previously, we have used drifting gratings to show that the phase sensitivity of complex cells increases at low contrast and after contrast adaptation while that of simple cells remains the same at all contrasts (Cloherty SL, Ibbotson MR. J Neurophysiol 113: 434-444, 2015; Crowder NA, van Kleef J, Dreher B, Ibbotson MR. J Neurophysiol 98: 1155-1166, 2007; van Kleef JP, Cloherty SL, Ibbotson MR. J Physiol 588: 3457-3470, 2010). However, drifting gratings confound the influence of spatial and temporal summation, so here we have stimulated complex cells with gratings that are spatially stationary but continuously reverse the polarity of the contrast over time (contrast-reversing gratings). By varying the spatial phase and contrast of the gratings we aimed to establish whether the contrast-dependent phase sensitivity of complex cells results from changes in spatial or temporal processing or both. We found that most of the increase in phase sensitivity at low contrasts could be attributed to changes in the spatial phase sensitivities of complex cells. However, at low contrasts the complex cells did not develop the spatiotemporal response characteristics of simple cells, in which paired response peaks occur 180° out of phase in time and space. Complex cells that increased their spatial phase sensitivity at low contrasts were significantly overrepresented in the supragranular layers of cortex. We conclude that complex cells in supragranular layers of cat cortex have dynamic spatial summation properties and that the mechanisms underlying complex cell receptive fields differ between cortical layers.

  14. Uric acid: a modulator of prostate cells and activin sensitivity.

    PubMed

    Sangkop, Febbie; Singh, Geeta; Rodrigues, Ely; Gold, Elspeth; Bahn, Andrew

    2016-03-01

    Elevated serum uric acid (SUA) or urate is associated with inflammation and gout. Recent evidence has linked urate to cancers, but little is known about urate effects in prostate cancer. Activins are inflammatory cytokines and negative growth regulators in the prostate. A hallmark of prostate cancer progression is activin insensitivity; however, mechanisms underlying this are unclear. We propose that elevated SUA is associated with prostate cancer counteracting the growth inhibitory effects of activins. The expression of activins A and B, urate transporter GLUT9 and tissue urate levels were examined in human prostate disease. Intracellular and secreted urate and GLUT9 expression were assessed in human prostate cancer cell lines. Furthermore, the effects of urate and probenecid, a known urate transport inhibitor, were determined in combination with activin A. Activin A expression was increased in low-grade prostate cancer, whereas activin B expression was reduced in high-grade prostate cancer. Intracellular urate levels decreased in all prostate pathologies, while GLUT9 expression decreased in benign prostatic hyperplasia, prostatitis and high-grade prostate cancer. Activin responsive LNCaP cells had higher intracellular and lower secreted urate levels than activin-insensitive PC3 cells. GLUT9 expression in prostate cancer cells was progressively lower than in prostate epithelial cells. Elevated extracellular urate was growth promoting in vitro, which was abolished by the gout medication probenecid, and it antagonized the growth inhibitory effects of activins. This study shows for the first time that a change in plasma or intracellular urate levels, possibly involving GLUT9 and a urate efflux transporter, has an impact on prostate cancer cell growth, and that lowering SUA levels in prostate cancer is likely to be therapeutically beneficial. PMID:26910779

  15. Development of Gravity Sensitive Plant Cells (Ceratodon) in Microgravity

    NASA Technical Reports Server (NTRS)

    Sack, Fred D.

    1999-01-01

    Protonemata of the moss Ceratodon are tip-growing cells that grow up in the dark. This cell type is unique compared to cells in almost any other organism, since the growth of the plant cell itself is completely oriented by gravity. Thus, both the processes of gravity sensing and the gravity response occur in the same cell. Gravity sensing appears to rely upon amyloplasts (starch-filled plastids) that sediment. This sedimentation occurs in specific zones and plastid zonation is complex with respect to plastid morphology, distribution, and gravity. Microtubules restrict the extent of plastid sedimentation (i.e., they are load-bearing). Light also is important since apical cells have a phytochrome-based positive phototropism, light quality influences plastid zonation and sedimentation (photomorphogenesis), and red light suppresses gravitropism at higher but not lower light intensities. Many of these processes were examined in a 16 day spaceflight experiment, "SPM-A" space moss" or "SPAM)) on STS-87 that landed in December, 1997. The work described here involves the definition of a second flight experiment that builds upon the data and questions arising from STS-87. Effort was directed towards further definition of an experiment for the Shuttle (dubbed "SOS" for "Son of SPAM"). Our current target is STS 107 that is scheduled to fly in January 2001. This definition addressed two goals of the STS107 experiment. The goals of the current experiment were to determine whether the cytoskeleton plays a role in maintaining and generating an apical (non-random) plastid distribution in microgravity and to determine the development and extent of clockwise spiral tip-growth in microgravity.

  16. Measuring beta-cell function relative to insulin sensitivity in youth: Does the hyperglycemic clamp suffice?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To compare beta-cell function relative to insulin sensitivity, disposition index (DI), calculated from two clamps (2cDI, insulin sensitivity from the hyperinsulinemic-euglycemic clamp and first-phase insulin from the hyperglycemic clamp) with the DI calculated from the hyperglycemic clamp alone (hcD...

  17. Oligocarbazole-based chromophores for efficient thin-film dye-sensitized solar cells.

    PubMed

    De Sousa, Samuel; Olivier, Céline; Ducasse, Laurent; Le Bourdon, Gwenaëlle; Hirsch, Lionel; Toupance, Thierry

    2013-06-01

    Carb your enthusiasm: Carbazole-based sensitizers with high extinction coefficients are synthesized for application in dye-sensitized solar cells (DSCs). The dyes perform efficiently with both iodine and cobalt electrolytes, showing power conversion efficiencies of up to 5.8% on TiO₂ films of 15 μm thickness, and retaining 90% of their efficiency in devices with thinner films.

  18. [Interaction of diphtheria toxin B subunit with sensitive and insensitive mammalian cells].

    PubMed

    Labyntsev, A Iu; Korotkevich, N V; Kaberniuk, A A; Romaniuk, S I; Kolybo, D V; Komisarenko, S V

    2010-01-01

    The recombinant fluorescent derivative of diphtheria toxin (EGFP-SbB) obtained by the replacement of toxin A subunit by enhanced green fluorescent protein (EGFP) has been used for visualization of the interaction of diphtheria toxin (DT) with sensitive and insensitive cells. It was shown that EGFP-SbB could interact with cell surface of both toxin-sensitive monkey cells (Vero cell line) and toxin-resistant mouse cells (3T3 cell line). The affinity of this protein for receptors of Vero cells was three times higher as compared with 3T3 cells. It was demonstrated that fluorescent derivate was able to interact with receptors of both cell lines and to internalize into these cells. Internalization of EGFP-SbB into the cells was inhibited by endocytosis inhibitor phenyl arsine oxide. We suppose that diverse sensitivity to DT of monkey and mouse cells can be explained not only by differences in their receptor affinity for DT but also by the processes that occur after internalization of the toxin into the cells.

  19. Charge Control Investigation of Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Otzinger, B.; Somoano, R.

    1984-01-01

    An ambient temperature rechargeable Li-TiS2 cell was cycled under conditions which simulate aerospace applications. A novel charge/discharge state-of-charge control scheme was used, together with tapered current charging, to overcome deleterious effects associated with end-of-charge and end-of-discharge voltages. The study indicates that Li-TiS2 cells hold promise for eventual synchronous satellite-type applications. Problem areas associated with performance degradation and reconditioning effects are identified.

  20. Controlled shutdown of a fuel cell

    DOEpatents

    Clingerman, Bruce J.; Keskula, Donald H.

    2002-01-01

    A method is provided for the shutdown of a fuel cell system to relieve system overpressure while maintaining air compressor operation, and corresponding vent valving and control arrangement. The method and venting arrangement are employed in a fuel cell system, for instance a vehicle propulsion system, comprising, in fluid communication, an air compressor having an outlet for providing air to the system, a combustor operative to provide combustor exhaust to the fuel processor.

  1. A festival of cell-cycle controls.

    PubMed

    Haase, S B; Clarke, D J

    2001-11-01

    The second biennial Salk Cell Cycle meeting convened on 22 June 2001 in San Diego, California. Organized by Tony Hunter and Susan Forsburg of the Salk Institute, the five-day conference was highlighted by enlightening science and plenty of San Diego sunshine. Presentations covered a broad range of contemporary cell-cycle topics, ranging from regulation of DNA replication and mitosis to DNA damage recognition and checkpoint control.

  2. Novel 4'-functionalized 4,4''-dicarboxyterpyridine ligands for ruthenium complexes: near-IR sensitization in dye sensitized solar cells.

    PubMed

    Koyyada, Ganesh; Botla, Vinayak; Thogiti, Suresh; Wu, Guohua; Li, Jingzhe; Fang, Xiaqin; Kong, Fantai; Dai, Songyuan; Surukonti, Niveditha; Kotamarthi, Bhanuprakash; Malapaka, Chandrasekharam

    2014-10-28

    Novel ruthenium complexes (MC113-MC117), obtained by modifying the terpyridine ligand of the black dye (N749), have been evaluated as sensitizers for dye sensitized solar cells (DSSCs). The modification is carried out by attaching selected chromophores, with varying electron donating strength, covalently to the central ring of the ligand. The complexes, compared to the parent dye, show red shifted absorption covering visible and near IR regions and higher molar extinction coefficients. We report in this work synthesis of a series of these ruthenium complexes with chromophores such as tert-butyl phenyl, triphenylamine, bithiophene, phenoxazine and phenothiazine. Detailed experimental characterization using optical, electrochemical and photovoltaic techniques has been carried out and complemented by density functional theory studies. The fill factors (ff) obtained for these dyes are larger than those of the parent black dye. In spite of these superior properties, the dyes show only moderate to good power conversion efficiencies. The possible reasons for this have been investigated and discussed.

  3. Enhanced Electron Lifetimes in Dye-Sensitized Solar Cells Using a Dichromophoric Porphyrin: The Utility of Intermolecular Forces.

    PubMed

    Zhao, Long; Wagner, Pawel; van der Salm, Holly; Gordon, Keith C; Mori, Shogo; Mozer, Attila J

    2015-10-01

    Electron lifetimes in dye-sensitized solar cells employing a porphyrin dye, an organic dye, a 1:1 mixture of the two dyes, and a dichromophoric dye design consisting of the two dyes using a nonconjugated linker were measured, suggesting that the dispersion force of the organic dyes has a significant detrimental effect on the electron lifetime and that the dichromophoric design can be utilized to control the effect of the dispersion force.

  4. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides.

    PubMed

    Birsoy, Kıvanç; Possemato, Richard; Lorbeer, Franziska K; Bayraktar, Erol C; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W; Clish, Clary B; Sabatini, David M

    2014-04-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here we developed a continuous-flow culture apparatus (Nutrostat) for maintaining proliferating cells in low-nutrient media for long periods of time, and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low-glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNA interference (RNAi) screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the OXPHOS upregulation that is normally caused by glucose limitation as a result of either mitochondrial DNA (mtDNA) mutations in complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, antidiabetic drugs that inhibit OXPHOS, when cancer cells are grown in low glucose or as tumour xenografts. Notably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of complex I function. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors.

  5. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides

    NASA Astrophysics Data System (ADS)

    Birsoy, Kıvanç; Possemato, Richard; Lorbeer, Franziska K.; Bayraktar, Erol C.; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W.; Clish, Clary B.; Sabatini, David M.

    2014-04-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here we developed a continuous-flow culture apparatus (Nutrostat) for maintaining proliferating cells in low-nutrient media for long periods of time, and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low-glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNA interference (RNAi) screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the OXPHOS upregulation that is normally caused by glucose limitation as a result of either mitochondrial DNA (mtDNA) mutations in complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, antidiabetic drugs that inhibit OXPHOS, when cancer cells are grown in low glucose or as tumour xenografts. Notably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of complex I function. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors.

  6. Enhancing the performance of quantum dots sensitized solar cell by SiO2 surface coating

    NASA Astrophysics Data System (ADS)

    Liu, Zhifu; Miyauchi, Masahiro; Uemura, Yu; Cui, Yan; Hara, Kohjiro; Zhao, Zhigang; Sunahara, Kenji; Furube, Akihiro

    2010-06-01

    This letter reports enhanced performance of quantum dots sensitized solar cells by selectively deposition an insulating SiO2 layer over the quantum dots (QDs) sensitized mesoporous TiO2 photoanode. The incident photon to current conversion efficiency of the CdS/CdSe QDs cosensitized solar cell with SiO2 coating can reach 83%. A power conversion efficiency of 2.05% was obtained.

  7. Langerhans cell migration: not necessarily always at the center of the skin sensitization universe.

    PubMed

    Kimber, Ian; Cumberbatch, Marie; Dearman, Rebecca J

    2009-08-01

    Since their discovery in 1868, the role of Langerhans cells (LCs) in skin immunity has been researched extensively. Recent data deriving from transgenic animals that are deficient in LCs have begun to challenge the dogma that there is a universal requirement for these cells in the development of skin sensitization. This Commentary addresses relationships between LC mobilization, draining lymph node activation, and skin sensitization using immunomodulators agonistic for a family of sphingosine-1-phosphate (S1P) receptors.

  8. Application of a sensitivity analysis technique to high-order digital flight control systems

    NASA Technical Reports Server (NTRS)

    Paduano, James D.; Downing, David R.

    1987-01-01

    A sensitivity analysis technique for multiloop flight control systems is studied. This technique uses the scaled singular values of the return difference matrix as a measure of the relative stability of a control system. It then uses the gradients of these singular values with respect to system and controller parameters to judge sensitivity. The sensitivity analysis technique is first reviewed; then it is extended to include digital systems, through the derivation of singular-value gradient equations. Gradients with respect to parameters which do not appear explicitly as control-system matrix elements are also derived, so that high-order systems can be studied. A complete review of the integrated technique is given by way of a simple example: the inverted pendulum problem. The technique is then demonstrated on the X-29 control laws. Results show linear models of real systems can be analyzed by this sensitivity technique, if it is applied with care. A computer program called SVA was written to accomplish the singular-value sensitivity analysis techniques. Thus computational methods and considerations form an integral part of many of the discussions. A user's guide to the program is included. The SVA is a fully public domain program, running on the NASA/Dryden Elxsi computer.

  9. Sensitizer localization and immune response in photodynamic therapy of B16 cells

    NASA Astrophysics Data System (ADS)

    Pop, S.-F.; Ion, R.-M.; Neagu, M.; Constantin, C.

    2011-03-01

    This paper proposes to extend the exploration of mouse melanoma B16 cells death by photodynamic therapy (PDT), under irradiation with different light sources and in the presence of 5,10,15,20-tetrap-sulphonato-phenyl-porphyrin (TSPP). The viability studies showed that B16 mouse melanoma is sensitive to photodynamic damage induced by TSPP 1 mM for either one, two, three or four hours. The control had TSPP added immediately prior to timelapse imaging (no incubation). They were then irradiated with red light He-Ne laser (λ = 632.8 nm, energy 180 J/cm2 for 20 min). Also, it has been used a laser diode GaInAs 25 mW/cm2, λ = 650 nm. The cells demonstrated clear morphological changes associated with apoptosis by mitochondrial pathway. There were changes in texture, as expected. Changes appeared to occur more quickly at lamp irradiation than at HeNe and GaInAs diode laser. Addition of TSPP just prior to exposure and observation, with no incubation, did not result in changes in cell morphology or cell death. Also, the proteins changes have been observed, because those with high molecular weights have been scissored under irradiation and this could be reason of the proteins concentrating in the area of low molecular weights, and the dissapearing of the proteic band of 75 kDa in the electrophoregramm. The immunized animals with B16-TSPP had the highest survival rate (40 days) by comparison with the control (death at 20 days) or with immunized animals with supernatants B16 (death at 25 days).

  10. Studies on the specific degranulation of mast cell sensitized by several allergens in vitro.

    PubMed

    Guo, Yongchao; Li, Zhenxing; Lin, Hong; Samee, Haider; Khalid, Jamil

    2009-04-01

    Food allergy is a major health issue worldwide. Mast cells play a very important role in the immediate hypersensitivity for which mast cell degranulation needs to be studied extensively. In this study, an approach was taken to study the characteristics of sensitized mast cell degranulation in vitro, which associated with the study of mast cells and animal models. BALB/c mice were immunized respectively by several food allergens, then blood and peritoneal mast cells were collected at different time points. A dynamic determination was carried out between mast cells and serumal IgE. Comparative analysis on sequential time points showed that there was a close coincidence between mast cell degranulation and IgE antibody titers in sensitized BALB/c mice. Furthermore, it is interesting that sensitized mast cells could implement specific degranulation against the challenges in vitro, but the closely tropomyosins induced mast cell degranulation displayed cross reactions. This is very similar to IgE resisting the allergens in vivo. The study disclosed some characteristics on mast cells, coming from sensitized BALB/c mice, degranulation in vitro.

  11. Translational control in germline stem cell development

    PubMed Central

    Slaidina, Maija

    2014-01-01

    Stem cells give rise to tissues and organs during development and maintain their integrity during adulthood. They have the potential to self-renew or differentiate at each division. To ensure proper organ growth and homeostasis, self-renewal versus differentiation decisions need to be tightly controlled. Systematic genetic studies in Drosophila melanogaster are revealing extensive regulatory networks that control the switch between stem cell self-renewal and differentiation in the germline. These networks, which are based primarily on mutual translational repression, act via interlocked feedback loops to provide robustness to this important fate decision. PMID:25313405

  12. Temporal Airy pulses control cell poration

    NASA Astrophysics Data System (ADS)

    Courvoisier, S.; Götte, N.; Zielinski, B.; Winkler, T.; Sarpe, C.; Senftleben, A.; Bonacina, L.; Wolf, J. P.; Baumert, T.

    2016-07-01

    We show that spectral phase shaping of fs-laser pulses can be used to optimize laser-cell membrane interactions in water environment. The energy and peak intensity thresholds required for cell poration with single pulse in the nJ range can be significantly reduced (25% reduction in energy and 88% reduction in peak intensity) by using temporal Airy pulses, controlled by positive third order dispersion, as compared to bandwidth limited pulses. Temporal Airy pulses are also effective to control the morphology of the induced pores, with prospective applications from cellular to tissue opto-surgery and transfection.

  13. Translational control in germline stem cell development.

    PubMed

    Slaidina, Maija; Lehmann, Ruth

    2014-10-13

    Stem cells give rise to tissues and organs during development and maintain their integrity during adulthood. They have the potential to self-renew or differentiate at each division. To ensure proper organ growth and homeostasis, self-renewal versus differentiation decisions need to be tightly controlled. Systematic genetic studies in Drosophila melanogaster are revealing extensive regulatory networks that control the switch between stem cell self-renewal and differentiation in the germline. These networks, which are based primarily on mutual translational repression, act via interlocked feedback loops to provide robustness to this important fate decision.

  14. Dye-sensitized solar cell using extract from petals of male flowers Luffa cylindrica L. as a natural sensitizer

    NASA Astrophysics Data System (ADS)

    Maurya, Ishwar Chandra; Srivastava, Pankaj; Bahadur, Lal

    2016-02-01

    The study reports use of natural dye extracted from petals of male flowers Luffa cylindrica L. as sensitizer for TiO2 based dye-sensitized solar cells. Optical characteristics of the dye extract and photoelectrochemical performance of the cells were studied. The extracts showed the UV-Vis absorptions in the 400-450 nm range with broad maxima at ∼430 nm. FTIR spectra of extract revealed the presence of anchoring groups and coloring constituents. DSSC was fabricated using natural dye loaded TiO2 photoelectrode, electrolyte containing I-/I3- redox mediator and Pt counter electrode by assembling them into a cell module. Conversion of solar light into electricity was successfully accomplished and DSSC based on petals of male flowers Luffa cylindrica L. extract exhibited an open-circuit voltage (Voc) of 0.52 V, short-circuit current density (Jsc) of 0.44 mA cm-2, Pmax 130 μW, fill factor (FF) of 0.60, conversion efficiency of 0.13% and IPCE ∼30% (at λ = 430 nm).

  15. Combinatorial control of heterogeneous cell populations

    NASA Astrophysics Data System (ADS)

    Piermarocchi, C.; Duxbury, P.; Paternostro, G.; Feala, J.; Tiziani, S.; Axelrod, J.; Chaudhury, A.; Choi, J.; McCulloch, A.; Cortes, J.

    2010-03-01

    In medicine, a recent pharmacological approach involves systematic discovery of combinatorial therapies, in which different drugs are simultaneously used to control different pathways associated with a cellular function. This control must occur with minimal response in other non-target cells exposed to treatment, i.e. it has to be selective. We have investigated the statistics of selective control of the human apoptosis (cell death) signaling network. We have built a model for a heterogeneous population of cells, characterized by a signaling network with identical topology, but having different link strengths. The control of the life/death signal is realized by acting with external perturbations, modeling the effect of drugs, on the nodes and on the signaling flow. Concepts from statistical physics and information theory, including entropy, frustration, and non-linearity have been used to characterize the general properties of selective control. This knowledge was used as a guide in designing algorithms for identifying selective perturbations. Some of these algorithms have been implemented in vitro in high throughput experiments on real cell lines where a large number of combinations of different drugs can be tested.

  16. Novel surface-enhanced Raman scattering-based assays for ultra-sensitive detection of human pluripotent stem cells.

    PubMed

    Han, Jingjia; Qian, Ximei; Wu, Qingling; Jha, Rajneesh; Duan, Jinshuai; Yang, Zhou; Maher, Kevin O; Nie, Shuming; Xu, Chunhui

    2016-10-01

    Human pluripotent stem cells (hPSCs) are a promising cell source for regenerative medicine, but their derivatives need to be rigorously evaluated for residual stem cells to prevent teratoma formation. Here, we report the development of novel surface-enhanced Raman scattering (SERS)-based assays that can detect trace numbers of undifferentiated hPSCs in mixed cell populations in a highly specific, ultra-sensitive, and time-efficient manner. By targeting stem cell surface markers SSEA-5 and TRA-1-60 individually or simultaneously, these SERS assays were able to identify as few as 1 stem cell in 10(6) cells, a sensitivity (0.0001%) which was ∼2000 to 15,000-fold higher than that of flow cytometry assays. Using the SERS assay, we demonstrate that the aggregation of hPSC-based cardiomyocyte differentiation cultures into 3D spheres significantly reduced SSEA-5(+) and TRA-1-60(+) cells compared with parallel 2D cultures. Thus, SERS may provide a powerful new technology for quality control of hPSC-derived products for preclinical and clinical applications. PMID:27509304

  17. C/EBPβ regulates sensitivity to bortezomib in prostate cancer cells by inducing REDD1 and autophagosome-lysosome fusion.

    PubMed

    Barakat, David J; Mendonca, Janet; Barberi, Theresa; Zhang, Jing; Kachhap, Sushant K; Paz-Priel, Ido; Friedman, Alan D

    2016-05-28

    The purpose of this study was to ascertain the mechanisms by which advanced prostate cancer cells resist bortezomib therapy. Several independent studies have shown that cells are protected from proteasome inhibition by increased autophagic activity. We investigated whether C/EBPβ, a transcription factor involved in the control of autophagic gene expression, regulates resistance to proteasome inhibition. In PC3 cells over-expressing C/EBPβ, turnover of autophagic substrates and expression of core autophagy genes were increased. Conversely, C/EBPβ knockdown suppressed autophagosome-lysosome fusion. We also found that C/EBPβ knockdown suppressed REDD1 expression to delay early autophagy, an effect rescued by exogenous REDD1. Cells with suppressed C/EBPβ levels showed delayed autophagy activation upon bortezomib treatment. Knockdown of C/EBPβ sensitized PC3 cells to bortezomib, and blockade of autophagy by chloroquine did not further increase cell death in cells expressing shRNA targeting C/EBPβ. Lastly, we observed a decreased growth of PC3 cells and xenografts with C/EBPβ knockdown and such xenografts were sensitized to bortezomib treatment. Our results demonstrate that C/EBPβ is a critical effector of autophagy via regulation of autolysosome formation and promotes resistance to proteasome inhibitor treatment by increasing autophagy.

  18. Control of stochastic sensitivity in a stabilization problem for gas discharge system

    SciTech Connect

    Bashkirtseva, Irina

    2015-11-30

    We consider a nonlinear dynamic stochastic system with control. A problem of stochastic sensitivity synthesis of the equilibrium is studied. A mathematical technique of the solution of this problem is discussed. This technique is applied to the problem of the stabilization of the operating mode for the stochastic gas discharge system. We construct a feedback regulator that reduces the stochastic sensitivity of the equilibrium, suppresses large-amplitude oscillations, and provides a proper operation of this engineering device.

  19. Knockdown of long noncoding RNA H19 sensitizes human glioma cells to temozolomide therapy.

    PubMed

    Jiang, Pengfei; Wang, Ping; Sun, Xiaoling; Yuan, Zhongshun; Zhan, Rucai; Ma, Xiangyu; Li, Weiguo

    2016-01-01

    Temozolomide (TMZ) is commonly used in glioma chemotherapy. However, a great clinical challenge for TMZ is chemoresistance. H19 transcripts are recognized as long noncoding RNAs, which potentially interact with chromatin-modifying complexes to regulate gene expression via epigenetic changes. Our data based on glioma patients showed that the expression of H19 was significantly upregulated in TMZ-resistant tumors compared with the TMZ-sensitive tumors. To determine the function of H19 in glioma, cell lines U87 and U251 were exposed to TMZ to establish TMZ-resistant clones U87(TMZ) and U251(TMZ). In U87(TMZ) and U251(TMZ), the expression level of H19 transcripts was increased compared to wild-type or nonresistant clones, as determined by real-time quantitative reverse transcription polymerase chain reaction. Concomitant treatment with small interfering RNA specifically targeting H19 and TMZ in resistant glioma clones resulted in decreased IC50 values for TMZ, and increased apoptotic rates than control small interfering RNA-treated cells. This was also evident by the increased PARP cleavage in resistant cells exposed to TMZ + si-H19. Furthermore, the reduced expression of H19 altered major drug resistance genes, such as MDR, MRP, and ABCG2, both at the mRNA and protein levels. Taken together, these findings suggest that H19 plays an important role in the development of TMZ resistance, and may represent a novel therapeutic target for TMZ-resistant gliomas. PMID:27366087

  20. Knockdown of long noncoding RNA H19 sensitizes human glioma cells to temozolomide therapy

    PubMed Central

    Jiang, Pengfei; Wang, Ping; Sun, Xiaoling; Yuan, Zhongshun; Zhan, Rucai; Ma, Xiangyu; Li, Weiguo

    2016-01-01

    Temozolomide (TMZ) is commonly used in glioma chemotherapy. However, a great clinical challenge for TMZ is chemoresistance. H19 transcripts are recognized as long noncoding RNAs, which potentially interact with chromatin-modifying complexes to regulate gene expression via epigenetic changes. Our data based on glioma patients showed that the expression of H19 was significantly upregulated in TMZ-resistant tumors compared with the TMZ-sensitive tumors. To determine the function of H19 in glioma, cell lines U87 and U251 were exposed to TMZ to establish TMZ-resistant clones U87TMZ and U251TMZ. In U87TMZ and U251TMZ, the expression level of H19 transcripts was increased compared to wild-type or nonresistant clones, as determined by real-time quantitative reverse transcription polymerase chain reaction. Concomitant treatment with small interfering RNA specifically targeting H19 and TMZ in resistant glioma clones resulted in decreased IC50 values for TMZ, and increased apoptotic rates than control small interfering RNA-treated cells. This was also evident by the increased PARP cleavage in resistant cells exposed to TMZ + si-H19. Furthermore, the reduced expression of H19 altered major drug resistance genes, such as MDR, MRP, and ABCG2, both at the mRNA and protein levels. Taken together, these findings suggest that H19 plays an important role in the development of TMZ resistance, and may represent a novel therapeutic target for TMZ-resistant gliomas. PMID:27366087

  1. The HPV-16 E7 oncogene sensitizes malignant cells to IFN-alpha-induced apoptosis

    SciTech Connect

    Wang, Yisong

    2005-10-01

    Interferons (IFNs) exert antitumor effects in several human malignancies, but their mechanism of action is unclear. There is a great variability in sensitivity to IFN treatment depending on both tumor type and the individual patient. The reason for this variable sensitivity is not known. The fact that several IFN-induced anticellular effects are exerted through modulation of proto-oncogenes and tumor suppressor genes may indicate that the malignant genotype may be decisive in the cell's sensitivity to IFN. To determine if a deregulated oncogene could alter the cellular response to IFN, a mouse lymphoma cell line (J3D) was stably transfected with the viral human papillomavirus-16 (HPV-16) E7 oncogene. The E7-transfected cells and their respective mock-transfected sister clones were treated with IFN-{alpha} and examined for possible IFN-induced anticellular effects. We found that the E7-transfected clones were greatly sensitized to IFN-{alpha}-induced apoptosis compared with their mock-transfected counterparts. Induction of apoptosis in the transfected cells correlated with the ability of IFN to activate parts of the proapoptotic machinery specifically in these cells, including activation of caspases and the proapoptotic protein Bak. In summary, our data suggest that transfection of malignant cells with the E7 oncogene can sensitize them to IFN-{alpha}-induced apoptosis. This demonstrates that an oncogenic event may alter the cellular sensitivity to IFN and might also have implications for treatment of HPV related diseases with IFN.

  2. Addiction: Decreased reward sensitivity and increased expectation sensitivity conspire to overwhelm the brain’s control circuit

    SciTech Connect

    Volkow, N.D.; Wang, G.; Volkow, N.D.; Wang, G.-J.; Fowler, J.S.; Tomasi, D.; Telang, F.; Baler, R.

    2010-07-01

    Based on brain imaging findings, we present a model according to which addiction emerges as an imbalance in the information processing and integration among various brain circuits and functions. The dysfunctions reflect (a) decreased sensitivity of reward circuits, (b) enhanced sensitivity of memory circuits to conditioned expectations to drugs and drug cues, stress reactivity, and (c) negative mood, and a weakened control circuit. Although initial experimentation with a drug of abuse is largely a voluntary behavior, continued drug use can eventually impair neuronal circuits in the brain that are involved in free will, turning drug use into an automatic compulsive behavior. The ability of addictive drugs to co-opt neurotransmitter signals between neurons (including dopamine, glutamate, and GABA) modifies the function of different neuronal circuits, which begin to falter at different stages of an addiction trajectory. Upon exposure to the drug, drug cues or stress this results in unrestrained hyperactivation of the motivation/drive circuit that results in the compulsive drug intake that characterizes addiction.

  3. Assembling Supramolecular Dye-Sensitized Photoelectrochemical Cells for Water Splitting.

    PubMed

    Ding, Xin; Gao, Yan; Ye, Lu; Zhang, Linlin; Sun, Licheng

    2015-12-01

    The method used to assemble dye-sensitized photoelectrochemical (DS-PEC) devices plays a vital role in determining its photoactivity and stability. We report a simple and effective method to assemble supramolecular DS-PECs introducing PMMA as support material and a catalyst modified with long carbon chains as photoanodes. The long carbon chains in combination with PMMA allow to better immobilize the catalyst. DS-PECs obtained by this simple method have display excellent photoactivities and stabilities. A photocurrent density of 1.1 mA cm(-2) and a maximum IPCE of 9.5 % have been obtained with a 0.2 V vs NHE external bias.

  4. In vitro primary sensitization and restimulation of hapten-specific T cells by fresh and cultured human epidermal Langerhans