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https://www.readbyqxmd.com/read/28431446/-vitamin-d-in-clinic-and-practice
#1
Armin Zittermann, Stefan Pilz
Vitamin D is unique among the vitamins, since its major source is skin synthesis by solar UVB exposure, whereas dietary intake plays only a minor role. In the general population, cutaneous vitamin D synthesis is clearly below the recommended amount. Dietary vitamin D does not fill this gap. Severe vitamin D deficiency results in rickets in infants and osteomalacia in adults. In the absence of endogenous vitamin D synthesis (e. g. during winter), oral supplements should ensure adequate daily vitamin D intake, where appropriate...
April 2017: Deutsche Medizinische Wochenschrift
https://www.readbyqxmd.com/read/28431206/phase-transfer-ligand-exchange-of-lead-chalcogenide-quantum-dots-for-direct-deposition-of-thick-highly-conductive-films
#2
Qianglu Lin, Hyeong Jin Yun, Wenyong Liu, Hyung-Jun Song, Nikolay S Makarov, Oleksandr Isaienko, Tom Nakotte, Gen Chen, Hongmei Luo, Victor I Klimov, Jeffrey M Pietryga
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires post-synthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport in QD films. Despite their importance to solar cells, and infrared (IR) light-emitting diodes and photodetectors, advances in these chemical treatments for lead chalcogenide (PbE, E = S, Se, Te) QDs have lagged behind those of, for instance, II-VI semiconductor QDs. Here, we introduce a method for fast and effective ligand exchange for PbE QDs in solution, resulting in QDs completely passivated by a wide range of small anionic ligands...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28430732/noninvasive-rcm-for-differentiation-of-melanotic-macules-from-melanocytic-lesions-blinded-evaluation-of-a-series-of-42-pigmented-macules
#3
Martin Laimer, Edith Arzberger, Clara-Anna Kirchner, Christine Prodinger, Rainer Hofmann-Wellenhof, Verena Ahlgrimm-Siess
BACKGROUND: Differentiation of melanotic macules from melanocytic lesions, most importantly of melanoma, is a common problem on clinical-dermoscopic examination. OBJECTIVE: To assess the value of noninvasive reflectance confocal microscopy (RCM) in the differential diagnosis of melanotic macules and melanocytic lesions. PATIENTS AND METHODS: Reflectance confocal microscopy images of 42 pigmented macules on mucocutaneous junctions of genitalia and lips, including 31 melanotic macules, 6 nevi, and 5 melanomas, were retrospectively and independently assessed in a blinded manner by one expert observer and 2 less experienced observers together...
April 19, 2017: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
https://www.readbyqxmd.com/read/28430539/metabolic-pathway-rewiring-in-engineered-cyanobacteria-for-solar-to-chemical-and-solar-to-fuel-production-from-co2
#4
Han Min Woo
Photoautotrophic cyanobacteria have been developed to convert CO2 to valuable chemicals and fuels as solar-to-chemical (S2C) and solar-to-fuel (S2F) platforms. Here, I describe the rewiring of the metabolic pathways in cyanobacteria to better understand the endogenous carbon flux and to enhance the yield of heterologous products. The plasticity of the cyanobacterial metabolism has been proposed to be advantageous for the development of S2C and S2F processes. The rewiring of the sugar catabolism and of the phosphoketolase pathway in the central cyanobacterial metabolism allowed for an enhancement in the level of target products by redirecting the carbon fluxes...
April 21, 2017: Bioengineered
https://www.readbyqxmd.com/read/28430473/first-direct-detection-constraints-on-ev-scale-hidden-photon-dark-matter-with-damic-at-snolab
#5
A Aguilar-Arevalo, D Amidei, X Bertou, M Butner, G Cancelo, A Castañeda Vázquez, B A Cervantes Vergara, A E Chavarria, C R Chavez, J R T de Mello Neto, J C D'Olivo, J Estrada, G Fernandez Moroni, R Gaïor, Y Guardincerri, K P Hernández Torres, F Izraelevitch, A Kavner, B Kilminster, I Lawson, A Letessier-Selvon, J Liao, A Matalon, V B B Mello, J Molina, P Privitera, K Ramanathan, Y Sarkis, T Schwarz, M Settimo, M Sofo Haro, R Thomas, J Tiffenberg, E Tiouchichine, D Torres Machado, F Trillaud, X You, J Zhou
We present direct detection constraints on the absorption of hidden-photon dark matter with particle masses in the range 1.2-30  eV c^{-2} with the DAMIC experiment at SNOLAB. Under the assumption that the local dark matter is entirely constituted of hidden photons, the sensitivity to the kinetic mixing parameter κ is competitive with constraints from solar emission, reaching a minimum value of 2.2×10^{-14} at 17  eV c^{-2}. These results are the most stringent direct detection constraints on hidden-photon dark matter in the galactic halo with masses 3-12  eV c^{-2} and the first demonstration of direct experimental sensitivity to ionization signals <12  eV from dark matter interactions...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430435/cu-in-halide-perovskite-cihp-solar-absorbers
#6
Xin-Gang Zhao, Dongwen Yang, Yuanhui Sun, Tianshu Li, Lijun Zhang, Liping Yu, Alex Zunger
The long-term chemical instability and the presence of toxic Pb in otherwise stellar solar absorber APbX3 made of organic molecules on the A site and halogens for X have hindered their large-scale commercialization. Previously explored ways to achieve Pb-free halide perovskites involved replacing Pb(2+) with other similar M(2+) cations in ns(2) electron configuration, e.g., Sn(2+) or by Bi(3+) (plus Ag(+)), but unfortunately this showed either poor stability (M = Sn) or weakly absorbing oversized indirect gaps (M = Bi), prompting concerns that perhaps stability and good optoelectronic properties might be contraindicated...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28430418/effects-of-small-polar-molecules-ma-and-h2o-on-degradation-processes-of-perovskite-solar-cells
#7
Chunqing Ma, Dong Shen, Jian Qing, Hrisheekesh Thachoth Chandran, Ming-Fai Lo, Chun-Sing Lee
Degradation mechanisms of methylammonium lead halide perovskite solar cells (PSCs) have drawn much attention recently. Herein, the bulk and surface degradation processes of the perovskite were differentiated for the first time by employing combinational studies using electrochemical impedance spectroscopy (EIS), capacitance frequency (CF), and X-ray diffraction (XRD) studies with particular attention on the roles of small polar molecules (MA(+) and H2O). CF study shows that short-circuit current density of the PSCs is increased by H2O at the beginning of the degradation process coupled with an increased surface capacitance...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28430415/omnidirectional-harvesting-of-weak-light-using-a-graphene-quantum-dot-modified-organic-silicon-hybrid-device
#8
Meng-Lin Tsai, Dung-Sheng Tsai, Libin Tang, Lih-Juann Chen, Shu Ping Lau, Jr-Hau He
Despite great improvements in traditional inorganic photodetectors and photovoltaics, more progress is needed in the detection/collection of light at low-level conditions. Traditional photodetectors tend to suffer from high noise when operated at room temperature; therefore these devices require additional cooling systems to detect weak or dim light. Conventional solar cells also face the challenge of poor light-harvesting capabilities in hazy or cloudy weather. The real world features such varying levels of light, which makes it important to develop strategies that allow optical devices to function when conditions are less than optimal...
April 21, 2017: ACS Nano
https://www.readbyqxmd.com/read/28430343/fabrication-and-characterization-of-indium-tin-oxide-films
#9
Shiuh-Chuan Her, Chun-Fu Chang
BACKGROUND: Transparent conducting oxide (TCO) films are of particular interest in the field of optoelectronics, due to the requirement for transparent electrodes in applications such as organic light-emitting diodes, solar cells and so on. The aim of this study was to obtain a better understanding of the effects of preparation temperature on indium tin oxide (ITO) films, to improve their performance for optoelectronic applications. METHODS: ITO films were deposited on glass substrate at different temperatures, using direct current (DC) magnetron sputtering...
April 5, 2017: Journal of Applied Biomaterials & Functional Materials
https://www.readbyqxmd.com/read/28430278/enhanced-enzymatic-reactions-by-solar-to-thermal-conversion-nanoparticles
#10
Xiaoling Wu, Gang Ou, Cheng Yang, Jun Ge, Hui Wu
In this study, we show that enzymatic reactions can be easily enhanced by visible light irradiation. It is a general method as demonstrated by several different types of enzymes, including amylase, cellulase and lipase, which are typically utilized in many industrial biocatalysis processes. Markedly different from conventional titanium dioxide (TiO2) nanoparticles which absorb UV light and generate little thermal energy, defect-rich Magnéli phase titanium oxide (Ti8O15) nanoparticles absorb solar light and provide a highly effective solar-to-thermal conversion, which greatly enhances enzymatic reactions...
April 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28429933/remarkably-enhancing-green-excitation-efficiency-for-solar-energy-utilization-red-phosphors-ba2zns3-eu-2-x-co-doped-halide-ions-x-cl-br-i
#11
Tingting Luo, Yun Du, Zhongxian Qiu, Yanmei Li, Xiaofang Wang, Wenli Zhou, Jilin Zhang, Liping Yu, Shixun Lian
Eu(2+)-activated Ba2ZnS3 has been reported as a red phosphor with a broad emission band peaking at 650 nm under blue excitation for white-LED. In this study, Ba2ZnS3:Eu(2+), X(-) (X = F, Cl, Br, I) phosphors doped with halide ions were prepared by traditional high-temperature solid-state reaction. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ba2ZnS3 crystals without dopant. The corresponding excitation spectra showed an additional broad band in the green region peaking at 550 nm when the phosphor was halogenated except by the smallest F(-)...
April 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28429812/hollow-hematite-single-crystals-deposited-with-ultra-thin-al2o3-by-atom-layer-deposition-for-improved-photoelectrochemical-performance
#12
Wei Jiao, Jingrui Wu, Siwen Cui, Ning Wei, Zia Ur Rahman, Meiyan Yu, Shougang Chen, Yangtao Zhou, Daoai Wang
Hematite (α-Fe2O3) is a red material with a band gap of about 2.0 eV, which indicates that it can absorb more solar light. It is a promising photocatalyst applied in many fields. In this paper, α-Fe2O3 single crystal hollow hexagonal bipyramids were synthesized by a simple one-pot hydrothermal method. The morphology and structure of the prepared α-Fe2O3 hollow hexagonal bipyramids were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The hollow single crystals show a good light absorption and performance in photodegradation of methylene blue (MB)...
April 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28429762/annealing-induced-re-crystallization-in-ch3nh3pbi3-xclx-for-high-performance-perovskite-solar-cells
#13
Yingguo Yang, Shanglei Feng, Meng Li, Weidong Xu, Guangzhi Yin, Zhaokui Wang, Baoquan Sun, Xingyu Gao
Using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as hole conductor, a series of inverted planar CH3NH3PbI3-xClx perovskite solar cells (PSCs) were fabricated based on perovskite annealed by an improved time-temperature dependent (TTD) procedure in a flowing nitrogen atmosphere for different time. Only after an optimum annealing time, an optimized power conversion efficiency of 14.36% could be achieved. To understand their performance dependence on annealing time, an in situ real-time synchrotron-based grazing incidence X-ray diffraction (GIXRD) was used to monitor a step-by-step gradual structure transformation from distinct mainly organic-inorganic hybrid materials into highly ordered CH3NH3PbI3 crystal during annealing...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28429683/biokinetics-of-yttrium-and-comparison-with-its-geochemical-twin-holmium
#14
Richard Wayne Leggett
The transition metal yttrium (Y, atomic number 39) is chemically similar to elements in the lanthanide family (atomic numbers 57-71) and is found with the lanthanides in rare earth ores. Yttrium and the lanthanide holmium are referred to as geochemical twins because they generally show little fractionation from metamorphic or weathering processes, due to their closely similar chemical properties and nearly identical ionic radii. Extensive measurements on rocks, soils, and meteorites indicate that the Y/Ho mass concentration ratio rarely falls far from the so-called chondritic or solar system ratio of ~26...
April 21, 2017: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/28429682/refractive-index-and-extinction-coefficient-of-nh2ch-nh2pbi3-perovskite-photovoltaic-material
#15
Ziang Xie, Shuren Sun, Yu Yan, Lili Zhang, Ruixiang Hou, Fuyang Tian, Guogang Qin
Very recently, the NH2CH=NH2PbI3 (FAPbI3) perovskite material has attracted much attention in fabricating solar cells (SCs). For a photovoltaic material, its refractive index and extinction coefficient, n(λ) and k(λ), as functions of λ, are important to study its optical properties and to estimate the power conversion efficiency potential for the SCs made of it. As far as we know, so far there is no reporting of n(λ) and k(λ) for the FAPbI3 material. In this article, with spectroscopic ellipsometry (SE) measurements, the n(λ) and k(λ), as well as Eg = 1...
April 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28429410/photoelectroreduction-toward-chemical-building-blocks
#16
Fengjiao Chen, Wei Cui, Jie Zhang, Yeyun Wang, Junhua Zhou, Yongpan Hu, Yanguang Li, Shuit-Tong Lee
Conventional photoelectrochemical cells utilize solar energy to drive the chemical conversion of water or CO2 into useful chemical fuels. Such processes are confronted with general challenges, including the low intrinsic activities and inconvenient storage and transportation of their gaseous products. A photoelectrochemical approach is proposed to drive the reductive production of industrial building-block chemicals and demonstrate that succinic acid and glyoxylic acid can be readily synthesized on Si nanowire array photocathodes free of any cocatalyst and at room temperature...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28429002/assembling-metallic-1t-mos2-nanosheets-with-inorganic-ligand-stabilized-quantum-dots-for-exceptional-solar-hydrogen-evolution
#17
Xu-Bing Li, Yu-Ji Gao, Hao-Lin Wu, Yang Wang, Qing Guo, Mao-Yong Huang, Bin Chen, Chen-Ho Tung, Li-Zhu Wu
Due to their enhanced light harvesting, favored interfacial charge transfer and excellent proton reduction activity, hybrid photocatalysts of metallic 1T-MoS2 nanosheets and inorganic-ligand stabilized CdSe/ZnS QDs obtained via a self-assembly approach can produce H2 gas with a rate of ∼155 ± 3.5 μmol h(-1) mg(-1) under visible-light irradiation (λ = 410 nm), the most exceptional performance of solar H2 evolution using MoS2 as a cocatalyst known to date.
April 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28428998/pbi2-heterogeneous-cap-induced-crystallization-for-an-efficient-ch3nh3pbi3-layer-in-perovskite-solar-cells
#18
Yangrunqian Wang, Jiawei Li, Qian Li, Weidong Zhu, Tao Yu, Xingyu Chen, Lu'an Yin, Yong Zhou, Xiaoyong Wang, Zhigang Zou
PbI2 heterogeneous-cap-induced crystallization with a face-to-face configuration is proposed to obtain efficient CH3NH3PbI3 perovskite films during thermal annealing. The films with large-size and dominative (110)-oriented grains can effectively boost the photovoltaic performance of the perovskite solar cells.
April 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28428872/are-whooping-cranes-destined-for-extinction-climate-change-imperils-recruitment-and-population-growth
#19
Matthew J Butler, Kristine L Metzger, Grant M Harris
Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes (Grus americana) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping crane recruitment throughout the species' life cycle (breeding, migration, wintering). Our method uses a repeated cross-validated absolute shrinkage and selection operator approach to identify drivers of recruitment...
April 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28428848/modeling-activity-patterns-of-wildlife-using-time-series-analysis
#20
Jindong Zhang, Vanessa Hull, Zhiyun Ouyang, Liang He, Thomas Connor, Hongbo Yang, Jinyan Huang, Shiqiang Zhou, Zejun Zhang, Caiquan Zhou, Hemin Zhang, Jianguo Liu
The study of wildlife activity patterns is an effective approach to understanding fundamental ecological and evolutionary processes. However, traditional statistical approaches used to conduct quantitative analysis have thus far had limited success in revealing underlying mechanisms driving activity patterns. Here, we combine wavelet analysis, a type of frequency-based time-series analysis, with high-resolution activity data from accelerometers embedded in GPS collars to explore the effects of internal states (e...
April 2017: Ecology and Evolution
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