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- Suzuki, N., et al.
(författare)
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THE HUBBLE SPACE TELESCOPE CLUSTER SUPERNOVA SURVEY. V. IMPROVING THE DARK- ENERGY CONSTRAINTS ABOVE z > 1 AND BUILDING AN EARLY-TYPE-HOSTED SUPERNOVA SAMPLE
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 746:1
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Tidskriftsartikel (refereegranskat)abstract
- We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope (HST) Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623 < z < 1.415. Of these SNe Ia, 14 pass our strict selection cuts and are used in combination with the world's sample of SNe Ia to derive the best current constraints on dark energy. Of our new SNe Ia, 10 are beyond redshift z = 1, thereby nearly doubling the statistical weight of HST-discovered SNe Ia beyond this redshift. Our detailed analysis corrects for the recently identified correlation between SN Ia luminosity and host galaxy mass and corrects the NICMOS zero point at the count rates appropriate for very distant SNe Ia. Adding these SNe improves the best combined constraint on dark-energy density,rho(DE)(z), at redshifts 1.0 < z < 1.6 by 18% (including systematic errors). For a flat. CDM universe, we find Omega(A) = 0.729 +/- 0.014 (68% confidence level (CL) including systematic errors). For a flat wCDM model, we measure a constant dark-energy equation-of-state parameter w = -1.013(-0.073)(+0.068) (68% CL). Curvature is constrained to similar to 0.7% in the owCDM model and to similar to 2% in a model in which dark energy is allowed to vary with parameters w(0) and w(a). Further tightening the constraints on the time evolution of dark energy will require several improvements, including high-quality multi-passband photometry of a sample of several dozenz > 1 SNe Ia. We describe how such a sample could be efficiently obtained by targeting cluster fields with WFC3 on board HST. The updated supernova Union2.1 compilation of 580 SNe is available at http://supernova.lbl.gov/Union.
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| 2. |
- Mandati, S., et al.
(författare)
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CuIn1-xGaxSe2 thin-film absorber layers for solar photovoltaics fabricated by two-stage pulsed current electrodeposition
- 2014
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Ingår i: Materials letters (General ed.). - 0167-577X .- 1873-4979. ; 118, s. 158-160
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Tidskriftsartikel (refereegranskat)abstract
- Single phase polycrystalline Copper Indium Gallium Diselenide (CIGS) thin-films for solar photovoltaic applications were fabricated by an economical two-stage method of Pulsed Current (PC) electrodeposition. Cu, Ga and Se were first co-deposited onto a Mo foil followed by deposition of In. The as-deposited films were annealed in Argon atmosphere at 550 C for 30 min and were further characterized to study their morphology, phase constitution, and optical absorption. The results revealed that the films have a compact morphology and are comprised of a crystalline chalcopyrite single phase CIGS. The bandgap of the CIGS films was found to be 1.27 eV from absorption studies. The photoelectrochemical studies revealed the p-type nature of CIGS films with improved photocurrent over that obtained for one-stage PC electrodeposited CIGS thin-films. © 2013 Elsevier B.V.
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| 3. |
- Mandati, S., et al.
(författare)
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Improved photoelectrochemical performance of Cu(In,Ga)Se2 thin films prepared by pulsed electrodeposition
- 2013
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Ingår i: Journal of Renewable and Sustainable Energy. - 1941-7012. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Solar cells based on polycrystalline Cu(In,Ga)Se2 absorber layers have yielded the highest conversion efficiency among all the thin-film technologies. CIGS thin-films possess large optical absorption coefficient (≈105 cm-1) and a suitable bandgap of ≈ 1.20 eV for an ideal stoichiometry of CuIn0.7Ga0.3Se2. In the present study, Direct Current (DC) and Pulsed Current (PC) electrodeposition techniques are employed to obtain the near ideal stoichiometric CIGS thin-films on a Mo foil using a two electrode system at a constant potential. Deposited films are annealed at 550 °C under Ar atmosphere. Characterization of the annealed CIGS films is performed using SEM-energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and photoelectrochemistry to study the morphology, stoichiometry, phase constitution, and the photoelectrochemical response. PC deposition offered suitable manipulation of various parameters, which has helped in obtaining a better quality stoichiometric single phase chalcopyrite structured CIGS thin films with the elimination of unwanted secondary phases like Cu2-xSe. An improved photoelectrochemical performance, characteristic of a p-type semiconductor, is observed for the PC deposited CIGS films. © 2013 AIP Publishing LLC.
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| 4. |
- Mandati, S., et al.
(författare)
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Pulsed electrodeposition of Cuinse2 thin films with morphology for solar cell applications
- 2013
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Ingår i: Journal of the Electrochemical Society. - 0013-4651 .- 1945-7111. ; 160:4, s. D173-D177
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Tidskriftsartikel (refereegranskat)abstract
- Copper indium diselenide (CuInSe2) films have been prepared by pulse electrodeposition technique on Molybdenum substrate followed by post-deposition annealing at 550°C. Optimization of pulse parameters by varying the pulse duration (duty cycle) in order to achieve high quality films has been reported. Appropriate manipulation of pulse parameters has resulted in a novel flake-like crystallite morphology and better control over the composition of individual elements. The CIS thin films were comprehensively characterized using SEM-EDS, FIB, XRD and UV-DRS to study their morphology, phase constitution, etc. and PEC (photoelectrochemistry) measurements were also carried out to ascertain the photoelectrochemical performance of the CIS absorber layer. The bandgap of the CIS films was determined to be 1.02 eV. The flake like crystallite morphology observed in CIS thin films under the optimized processing conditions was found to yield enhanced cathodic photoresponse under solar simulated light with a photocurrent density of 20 μA/cm2 (observed at a potential of -0.6 V vs. SCE). The films exhibited a photoresponse typical of a p-type semiconductor. © 2013 The Electrochemical Society.
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| 9. |
- Kiseleva, E. P., et al.
(författare)
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Isolation and structural identification of glycopolymers of Bifidobacterium bifidum BIM B-733D as putative players in pathogenesis of autoimmune thyroid diseases
- 2013
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Ingår i: Beneficial microbes. - 1876-2891. ; 4:4, s. 375-391
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Tidskriftsartikel (refereegranskat)abstract
- Bifidobacterium bifidum 791 (commercially available as B. bifidum BIM B-733D) cell-surface biopolymers (BPs) interact selectively with human serum thyroid peroxidase (TPO) and thyroglobulin (Tg) autoantibodies (anti-TPO and anti-Tg, respectively). BPanti-TPO and BPanti-Tg were isolated from the soluble fraction of B. bifidum BIM B-733D by affinity chromatography with anti-TPO or anti-Tg, respectively. Homogeneity of affinity eluates (AE(anti-TPO) and AE(anti-Tg)) was tested by size exclusion chromatography. For each AE, the elution profiles generated on the basis of absorbance at 280 nm do not conform to ELISA data for functional activity characteristic of BPs. Moreover, high functional activity was detected in chromatographic fractions that had significantly different molecular weights and no absorbance at 280 nm, which suggests a non-protein (carbohydrate) nature of BPanti-TPO and BPanti-Tg. The semi-preparative size exclusion chromatography of AE(anti-TPO) and AE(anti-Tg) with detection by refractometer gave 5,000-7,000 Da fractions containing substances that interact selectively with either anti-TPO (BPanti-TPO) or anti-Tg (BPanti-Tg) according to ELISA data. Analysis by two-dimensional NMR spectroscopy including a H-1, C-13-heteronuclear single-quantum coherence experiment indicated that both substances are linear alpha-1,6-glucans. For the first time, an immunological similarity (molecular mimicry) of glycopolymers of B. bifidum BIM B-733D and human thyroid proteins, TPO and Tg, was shown. On the whole, our data point to a possible role of bifidobacteria in the pathogenesis of autoimmune thyroid diseases (ATD). The main requirements for triggering/acceleration or prevention/abrogation of ATD by bifidobacteria through molecular mimicry mechanism are hypothesised to be (1) genetic predisposition to ATD and (2) intestinal epithelium penetration by alpha-1,6-glucan.
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