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https://www.readbyqxmd.com/read/28725399/optimizing-performance-of-nonparametric-species-richness-estimators-under-constrained-sampling
#1
Harshana Rajakaruna, D Andrew R Drake, Farrah T Chan, Sarah A Bailey
Understanding the functional relationship between the sample size and the performance of species richness estimators is necessary to optimize limited sampling resources against estimation error. Nonparametric estimators such as Chao and Jackknife demonstrate strong performances, but consensus is lacking as to which estimator performs better under constrained sampling. We explore a method to improve the estimators under such scenario. The method we propose involves randomly splitting species-abundance data from a single sample into two equally sized samples, and using an appropriate incidence-based estimator to estimate richness...
October 2016: Ecology and Evolution
https://www.readbyqxmd.com/read/28722307/localized-defects-on-copper-sulfide-surface-for-enhanced-plasmon-resonance-and-water-splitting
#2
Kaixv Ren, Pengfei Yin, Yuzhu Zhou, Xingzhong Cao, Cunku Dong, Lan Cui, Hui Liu, Xiwen Du
Surficial defects in semiconductor can induce high density of carriers and cause localized surface plasmon resonance which is prone to light harvesting and energy conversion, while internal defects may cause serious recombination of electrons and holes. Thus, it is significant to precisely control the distribution of defects, although there are few successful examples. Herein, an effective strategy to confine abundant defects within the surface layer of Cu1.94 S nanoflake arrays (NFAs) is reported, leaving a perfect internal structure...
July 19, 2017: Small
https://www.readbyqxmd.com/read/28722265/control-of-redox-events-by-dye-encapsulation-applied-to-light-driven-splitting-of-hydrogen-sulfide
#3
Xu Jing, Yang Yang, Cheng He, Zhiduo Chang, Joost N H Reek, Chunying Duan
Inspired by the pocket feature of enzymes, a synthetic platform to combine photocatalytic hydrogen evolution with sulfide oxidation in a one-pot process via control over the location of electron transfer steps is reported in this paper. The redox-active coordination vessel Ni-TFT, which exhibits an octahedral pocket, encapsulates an organic dye to pre-organize for photocatalytic proton reduction via an oxidative quenching pathway using the nickel corners as catalysts, generating molecular hydrogen and the oxidized dye...
July 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28721942/induced-dipole-in-vanadium-doped-zinc-oxide-nanosheets-and-its-effects-on-photoelectrochemical-water-splitting
#4
Song Mi Lee, Sung-Ho Shin, Junghyo Nah, Min Hyung Lee
Appropriate control of energy band bending at the interface between semiconductors and electrolytes are closely related to performance of photoelectrochemical (PEC) water splitting. Dipoles formed near the surface of semiconductors induces energy band bending at the interface. Energy band bending control has been demonstrated by employing charged molecules and piezoelectric materials. However, chemical and piezoelectric approaches have demerit of chemical instability and inducement of instantaneous dipole, respectively...
July 19, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28721404/accurate-determination-of-the-charge-transfer-efficiency-of-photoanodes-for-solar-water-splitting
#5
Dino Klotz, Daniel A Grave, Avner Rothschild
The oxygen evolution reaction (OER) at the surface of semiconductor photoanodes is critical for photoelectrochemical water splitting. This reaction involves photo-generated holes that oxidize water via charge transfer at the photoanode/electrolyte interface. However, a certain fraction of the holes that reach the surface recombine with electrons from the conduction band, giving rise to the surface recombination loss. The charge transfer efficiency, ηt, defined as the ratio between the flux of holes that contribute to the water oxidation reaction and the total flux of holes that reach the surface, is an important parameter that helps to distinguish between bulk and surface recombination losses...
July 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28720281/evaluation-of-a-primary-course-of-h9n2-vaccine-with-or-without-as03-adjuvant-in-adults-a-phase-i-ii-randomized-trial
#6
Anuradha Madan, Harry Collins, Eric Sheldon, Louise Frenette, Laurence Chu, Damien Friel, Mamadou Drame, David W Vaughn, Bruce L Innis, Anne Schuind
BACKGROUND: Avian influenza A H9N2 strains have pandemic potential. METHODS: In this randomized, observer-blind study (ClinicalTrials.gov: NCT01659086), 420 healthy adults, 18-64years of age, received 1 of 10 H9N2 inactivated split-virus vaccination regimens (30 participants per group), or saline placebo (120 participants). H9N2 groups received 2 doses (days 0, 21) of 15µg hemagglutinin (HA) without adjuvant, or 1.9µgHA+AS03A, 1.9µgHA+AS03B, 3.75µgHA+AS03A, or 3...
July 15, 2017: Vaccine
https://www.readbyqxmd.com/read/28718766/structural-insights-into-the-light-driven-auto-assembly-process-of-the-water-oxidizing-mn4cao5-cluster-in-photosystem-ii
#7
Miao Zhang, Martin Bommer, Ruchira Chatterjee, Rana Hussein, Junko Yano, Holger Dau, Jan Kern, Holger Dobbek, Athina Zouni
In plants, algae and cyanobacteria, Photosystem II (PSII) catalyzes the light-driven splitting of water at a protein-bound Mn4CaO5-cluster, the water-oxidizing complex (WOC). In the photosynthetic organisms, the light-driven formation of the WOC from dissolved metal ions is a key process because it is essential in both initial activation and continuous repair of PSII. Structural information is required for understanding of this chaperone-free metal-cluster assembly. For the first time, we obtained a structure of PSII from Thermosynechococcus elongatus without the Mn4CaO5-cluster...
July 18, 2017: ELife
https://www.readbyqxmd.com/read/28718467/how-to-make-an-efficient-and-robust-molecular-catalyst-for-water-oxidation
#8
Pablo Garrido-Barros, Carolina Gimbert-Suriñach, Roc Matheu, Xavier Sala, Antoni Llobet
Energy has been a central subject for human development from Homo erectus to date. The massive use of fossil fuels during the last 50 years has generated a large CO2 concentration in the atmosphere that has led to the so-called global warming. It is very urgent to come up with C-neutral energy schemes to be able to preserve Planet Earth for future generations to come and still preserve our modern societies' life style. One of the potential solutions is water splitting with sunlight (hν-WS) that is also associated with "artificial photosynthesis", since its working mode consists of light capture followed by water oxidation and proton reduction processes...
July 18, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28718291/porous-structured-ni-fe-p-nanocubes-derived-from-prussian-blue-analogue-as-electrocatalyst-for-efficient-overall-water-splitting
#9
Cuijuan Xuan, Jie Wang, Weiwei Xia, Zongkai Peng, Zexing Wu, Wen Lei, Kedong Xia, Huolin L Xin, Deli Wang
Exploring non-precious metal electrocatalysts to replace the noble metal based catalysts for full water electrocatalysis is still an ongoing challenge. In this work, porous structured ternary nickel-iron-phosphides (Ni-Fe-P) nanocubes were synthesized through one-step phosphidation of Ni-Fe based Prussian blue analogue. The Ni-Fe-P nanocubes exhibit rough and loose porous structure on the surface under suitable phosphating temperature, which is favorable for the mass transfer and oxygen diffusion during electrocatalysis process...
July 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28715892/ethanol-solvation-in-water-studied-on-a-molecular-scale-by-photoelectron-spectroscopy
#10
Ricardo R T Marinho, Marie-Madeleine Walz, Victor Ekholm, Gunnar Öhrwall, Olle Bjorneholm, Arnaldo Naves de Brito
Due to the amphiphilic properties of alcohols, hydrophobic hydration is important in alcohol-water system. In the present paper we employ X-ray photoelectron spectroscopy (XPS) to investigate the bulk and surface molecular structure of ethanol-water mixtures from 0.2 to 95 mol%. The observed XPS binding energy splitting between the methyl C1s and hydroxymethyl C1s groups, (BES_[CH3‑CH2OH]), as a function of the ethanol molar percentage can be divided into different regions: one below 35 mol% with higher values (about 1...
July 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28715878/substitutional-doping-for-aluminosilicate-mineral-and-superior-water-splitting-performance
#11
Yi Zhang, Liangjie Fu, Zhan Shu, Huaming Yang, Aidong Tang, Tao Jiang
Substitutional doping is a strategy in which atomic impurities are optionally added to a host material to promote its properties, while the geometric and electronic structure evolution of natural nanoclay mineral upon substitutional metal doping is still ambiguous. This paper first designed an efficient lanthanum (La) doping strategy for nanotubular clay (halloysite nanotube, HNT) through the dynamic equilibrium of a substitutional atom in the presence of saturated AlCl3 solution, and systematic characterization of the samples was performed...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28715000/enhanced-photoelectrochemical-water-splitting-by-oxides-heterojunction-photocathode-coupled-with-ag
#12
Xue Lu, Zhifeng Liu
A novel one-dimensional Co3O4/CuO/Ag composite structure film was directly grown on indium tin oxide glass substrate by a simple hydrothermal method and electrodeposition method. The film was employed for the first time as a photocathode for photoelectrochemical (PEC) water splitting to generate hydrogen. The photocurrent density of the Co3O4/CuO/Ag composite structure achieved -5.13 mA cm(-2) at -0.2 V vs. RHE, which is roughly 12.8 times that of 1D Co3O4 nanowires and 3.31 times Co3O4/CuO heterojunction photocathodes...
July 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28714982/dynamic-surface-self-reconstruction-is-the-key-of-highly-active-perovskite-nano-electrocatalysts-for-water-splitting
#13
Emiliana Fabbri, Maarten Nachtegaal, Tobias Binninger, Xi Cheng, Bae-Jung Kim, Julien Durst, Francesco Bozza, Thomas Graule, Robin Schäublin, Luke Wiles, Morgan Pertoso, Nemanja Danilovic, Katherine E Ayers, Thomas J Schmidt
The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts...
July 17, 2017: Nature Materials
https://www.readbyqxmd.com/read/28714664/iron-doped-nickel-phosphide-nanosheet-arrays-an-efficient-bifunctional-electrocatalyst-for-water-splitting
#14
Pengyan Wang, Zonghua Pu, Yanhui Li, Lin Wu, Zhengkai Tu, Min Jiang, Zongkui Kou, Ibrahim Saana Amiinu, Shichun Mu
Exploring efficient and earth-abundant electrocatalysts for water splitting is crucial for various renewable energy technologies. In this work, iron (Fe)-doped nickel phosphide (Ni2P) nanosheet arrays supported on nickel foam (Ni1.85Fe0.15P NSAs/NF) are fabricated through a facile hydrothermal method followed by phosphorization. The electrochemical analysis demonstrates that the Ni1.85Fe0.15P NSAs/NF electrode possesses high electrocatalytic activity for water splitting. In 1.0 M KOH, the Ni1.85Fe0.15P NSAs/NF electrode only needs overpotentials of 106 mV at 10 mA cm-2 and 270 mV at 20 mA cm-2 to drive hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively...
July 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28714231/a-highly-versatile-and-adaptable-artificial-leaf-with-floatability-and-planar-compact-design-applicable-in-various-natural-environments
#15
Sangkuk Kim, Taewan Kim, Seunghyup Lee, Seunghyeon Baek, Taiho Park, Kijung Yong
As a promising means of solar energy conversion, photovoltaic (PV) cell-based electrolysis has recently drawn considerable attention for its effective solar fuel generation; especially the generation of hydrogen by solar water splitting. Inspired by remarkable accomplishments in enhancing the solar-to-hydrogen conversion efficiency, various efforts have aimed at fostering convenient and practical uses of PV electrolysis to make this technology ubiquitous, manageable, and efficient. Here, the design and function of a monolithic photoelectrolysis system-a so-called artificial leaf-for use in various environments are highlighted...
July 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28714078/ternary-porous-cobalt-phosphoselenide-nanosheets-an-efficient-electrocatalyst-for-electrocatalytic-and-photoelectrochemical-water-splitting
#16
Yang Hou, Ming Qiu, Tao Zhang, Xiaodong Zhuang, Chang-Soo Kim, Chris Yuan, Xinliang Feng
Exploring efficient and earth-abundant electrocatalysts is of great importance for electrocatalytic and photoelectrochemical hydrogen production. This study demonstrates a novel ternary electrocatalyst of porous cobalt phosphoselenide nanosheets prepared by a combined hydrogenation and phosphation strategy. Benefiting from the enhanced electric conductivity and large surface area, the ternary nanosheets supported on electrochemically exfoliated graphene electrodes exhibit excellent catalytic activity and durability toward hydrogen evolution in alkali, achieving current densities of 10 and 20 mA cm(-2) at overpotentials of 150 and 180 mV, respectively, outperforming those reported for transition metal dichalcogenides and first-row transition metal pyrites catalysts...
July 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28711052/diffusion-and-reaction-pathways-of-water-near-fully-hydrated-tio2-surfaces-from-ab-initio-molecular-dynamics
#17
Lorenzo Agosta, Erik G Brandt, Alexander P Lyubartsev
Ab initio molecular dynamics simulations are reported for water-embedded TiO2 surfaces to determine the diffusive and reactive behavior at full hydration. A three-domain model is developed for six surfaces [rutile (110), (100), and (001), and anatase (101), (100), and (001)] which describes waters as "hard" (irreversibly bound to the surface), "soft" (with reduced mobility but orientation freedom near the surface), or "bulk." The model explains previous experimental data and provides a detailed picture of water diffusion near TiO2 surfaces...
July 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28707892/redox-electrocatalysis-of-floating-nanoparticles-determining-electrocatalytic-properties-without-the-influence-of-solid-supports
#18
Pekka Peljo, Micheál D Scanlon, Astrid Johana Olaya, Lucie Rivier, Evgeny Smirnov, Hubert H Girault
Redox electrocatalysis (catalysis of electron transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration and at liquid-liquid interfaces are provided, highlighting that bipolar and liquid-liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid-liquid interfaces allow measurement of the electrocatalytic current directly...
July 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28707342/ratio-of-ellipticities-between-192-and-208-nm-r1-an-effective-electronic-circular-dichroism-parameter-for-characterization-of-the-helical-components-of-proteins-and-peptides
#19
Raja Banerjee, Tridip Sheet
Circular dichroism (CD) spectroscopy represents an important tool for characterization of the peptide and protein secondary structures that mainly arise from the conformational disposition of the peptide backbone in solution. In 1991 Manning and Woody proposed that, in addition to the signal intensity, the ratio between [θ]nπ* and [θ]ππ*ǁ ((R2 ) ≅ [θ]222 /[θ]208 ), along with [θ]ππ*⊥ and [θ]ππ*ǁ ((R1 ) ≅ [θ]192 /[θ]208 ), may be utilized towards identifying the peptide/protein conformation (especially 310 - and α-helices)...
July 13, 2017: Proteins
https://www.readbyqxmd.com/read/28706763/comparison-of-knowledge-attitudes-and-practices-of-educated-and-uneducated-adults-regarding-human-immunodeficiency-virus-in-karachi-pakistan
#20
Zainab Ahmad, Sara Sadiq, Mariam Asghar, Alizay Rashid Khan, Omer Arif, Syed Hamza Shah, Shahrukh Nadeem, Yamna Waseem, Rafi Aibani, Ammar Salman Syed, Rabia M Mustafa, Zainab Abdulrahman, Kaneez Fatima
BACKGROUND: Despite the high prevalence of human immunodeficiency virus (HIV) in Pakistan, no prior work has been done to specifically highlight the importance of education as a social vaccine against HIV. Therefore, our study focuses on differences in knowledge and practices regarding HIV and acquired immunodeficiency syndrome (AIDS) among educated and uneducated adults. METHODOLOGY: A cross-sectional study was carried out in which data was collected from all over Karachi...
June 12, 2017: Curēus
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