Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies
. Previous attempts to control water ...permeation through membranes (mainly polymeric ones) have concentrated on modulating the structure of the membrane and the physicochemical properties of its surface by varying the pH, temperature or ionic strength
. Electrical control over water transport is an attractive alternative; however, theory and simulations
have often yielded conflicting results, from freezing of water molecules to melting of ice
under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes
. Such membranes have previously been shown to exhibit ultrafast permeation of water
and molecular sieving properties
, with the potential for industrial-scale production. To achieve electrical control over water permeation, we create conductive filaments in the graphene oxide membranes via controllable electrical breakdown. The electric field that concentrates around these current-carrying filaments ionizes water molecules inside graphene capillaries within the graphene oxide membranes, which impedes water transport. We thus demonstrate precise control of water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for developing smart membrane technologies for artificial biological systems, tissue engineering and filtration.
A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3− in air and/or ...precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet/bulk deposition fluxes (2.9–83.3 kg N ha−1 yr−1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha−1 yr−1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.
Micro-structural evolution and grain refinement in ANSI 304 stainless steel subjected to multiple laser shock processing (LSP) impacts were investigated by means of cross-sectional optical microscopy ...and transmission electron microscopy observations. The plastic strain-induced grain refinement mechanism of the face-centered cubic (fcc) materials with very low stacking fault energy was identified. The micro-structure was obviously refined due to the ultra-high plastic strain induced by multiple LSP impacts. The minimum grain size in the top surface was about 50–200
nm. Multidirectional mechanical twin matrix (MT)–MT intersections led to grain subdivision at the top surface during multiple LSP impacts. Furthermore, a novel structure with submicron triangular blocks was found at the top surface subjected to three LSP impacts. The grain refinement process along the depth direction after multiple LSP impacts can be described as follows: (i) formation of planar dislocation arrays (PDAs) and stacking faults along multiple directions due to the pile up of dislocation lines; (ii) formation of submicron triangular blocks (or irregularly shaped blocks) by the intersection of MT–MT (or MT–PDA or PDA–PDA) along multiple directions; (iii) transformation of MTs into subgrain boundaries; (iv) evolution by continuous dynamic recrystallization of subgrain boundaries to refined grain boundaries. The experimental results and analyses indicate that a high strain with an ultra-high strain rate play a crucial role in the grain refinement process of fcc materials subjected to multiple LSP impacts.
In late 2019, a novel human coronavirus – severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) – emerged in Wuhan, China. This virus has caused a global pandemic involving more than 200 ...countries. SARS-CoV-2 is highly adapted to humans and readily transmits from person-to-person.
To investigate the infectivity of SARS-CoV-2 under various environmental and pH conditions. The efficacies of various laboratory virus inactivation methods and home disinfectants against SARS-CoV-2 were investigated.
The residual virus in dried form or in solution was titrated on to Vero E6 cells on days 0, 1, 3, 5 and 7 after incubation at different temperatures. Viral viability was determined after treatment with various disinfectants and pH solutions at room temperature (20–25oC).
SARS-CoV-2 was able to retain viability for 3–5 days in dried form or 7 days in solution at room temperature. SARS-CoV-2 could be detected under a wide range of pH conditions from pH 4 to pH 11 for several days, and for 1–2 days in stool at room temperature but lost 5 logs of infectivity. A variety of commonly used disinfectants and laboratory inactivation procedures were found to reduce viral viability effectively.
This study demonstrated the stability of SARS-CoV-2 on environmental surfaces, and raises the possibility of faecal–oral transmission. Commonly used fixatives, nucleic acid extraction methods and heat inactivation were found to reduce viral infectivity significantly, which could ensure hospital and laboratory safety during the SARS-CoV-2 pandemic.
Severe regional haze pollution events occurred in eastern and central China in January 2013, which had adverse effects on the environment and public health. Extremely high levels of particulate ...matter with aerodynamic diameter of 2.5 μm or less (PM2.5) with dominant components of sulfate and nitrate are responsible for the haze pollution. Although heterogeneous chemistry is thought to play an important role in the production of sulfate and nitrate during haze episodes, few studies have comprehensively evaluated the effect of heterogeneous chemistry on haze formation in China by using the 3-D models due to of a lack of treatments for heterogeneous reactions in most climate and chemical transport models. In this work, the WRF-CMAQ model with newly added heterogeneous reactions is applied to East Asia to evaluate the impacts of heterogeneous chemistry and the meteorological anomaly during January 2013 on regional haze formation. As the parameterization of heterogeneous reactions on different types of particles is not well established yet, we arbitrarily selected the uptake coefficients from reactions on dust particles and then conducted several sensitivity runs to find the value that can best match observations. The revised CMAQ with heterogeneous chemistry not only captures the magnitude and temporal variation of sulfate and nitrate, but also reproduces the enhancement of relative contribution of sulfate and nitrate to PM2.5 mass from clean days to polluted haze days. These results indicate the significant role of heterogeneous chemistry in regional haze formation and improve the understanding of the haze formation mechanisms during the January 2013 episode.
Along with the growth of Internet and electronic commerce, online consumer reviews have become an important source of information that assists consumers to make purchase decision. However, ...theoretical development and empirical testing in this area of research are still limited, which greatly hinder us from understanding the influence of online reviews. Drawing upon the heuristic–systematic model from the literature of dual-process theories, we develop a research model to identify factors that are important to consumers' purchase decision-making. The model is empirically tested with 191 users of an existing online review site. We find that argument quality of online reviews (systematic factor), which is characterized by perceived informativeness and perceived persuasiveness, has a significant effect on consumers' purchase intention. In addition, we find that source credibility and perceived quantity of reviews (heuristic factors) have direct impacts on purchase intention. The two heuristic factors further demonstrate positive influences on argument strength. This result is consistent with the proposition of bias effect in the heuristic–systematic model, which elucidates the interrelationship between heuristic and systematic factors. Based on the findings, we discuss implications for both researchers and practitioners.
•We develop a heuristic–systematic model to examine the influence of online reviews.•Three systematic and heuristic factors are proposed to affect behavioral intention.•Argument quality is defined with informativeness and persuasiveness dimensions.•Source credibility and perceived quantity of reviews are the two heuristic factors.•The two heuristic factors produce significant bias effects on argument quality.
A novel coronavirus (SCoV) is the etiological agent of severe acute respiratory syndrome (SARS). SCoV-like viruses were isolated from Himalayan palm civets found in a live-animal market in Guangdong, ...China. Evidence of virus infection was also detected in other animals (including a raccoon dog, Nyctereutes procyonoides) and in humans working at the same market. All the animal isolates retain a 29-nucleotide sequence that is not found in most human isolates. The detection of SCoV-like viruses in small, live wild mammals in a retail market indicates a route of interspecies transmission, although the natural reservoir is not known.
We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor νover ¯_{e} inverse β decay candidates observed over 1958 days ...of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative νover ¯_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the inverted hierarchy.
Development of advanced high energy density lithium ion batteries is important for promoting electromobility. Making electric vehicles attractive and competitive compared to conventional automobiles ...depends on the availability of reliable, safe, high power, and highly energetic batteries whose components are abundant and cost effective. Nickel rich LiNi
x
Co
y
Mn
1−x−y
O
2
layered cathode materials (
x
> 0.5) are of interest because they can provide very high specific capacity without pushing charging potentials to levels that oxidize the electrolyte solutions. However, these cathode materials suffer from stability problems. We discovered that doping these materials with tungsten (1 mol%) remarkably increases their stability due to a partial layered to cubic (rock salt) phase transition. We demonstrate herein highly stable Li ion battery prototypes consisting of tungsten-stabilized Ni rich cathode materials (
x
> 0.9) with specific capacities >220 mA h g
-1
. This development can increase the energy density of Li ion batteries more than 30% above the state of the art without compromising durability.
A low level of CD4+ lymphocyte cells makes end-stage HIV/AIDS patients highly susceptible to microbial infections. We have adopted the next generation sequencing method to identify the spectrum of ...bacterial plasma and viral elements that might be present in these patients. The HIV/AIDS plasma microbiome was dominated by bacterial elements in the taxonomical order Pseudomonadales, while healthy people carried fewer bacterial DNA in the plasma. We have found that many of the bacterial elements in HIV/AIDS plasma are similar to those of the microbes found in the human gut, suggesting potential acquisition of microbial elements from the gut. The HIV/AIDS and normal plasma DNA virome shared some similarities in the presence of common ubiquitous eukaryotic viruses. The normal DNA virome was mainly composed of viruses from Anelloviridae. In contrast, the HIV/AIDS DNA virome contained a large proportion of bacteriophages, endogenous retroviruses and a non-human virus. In addition, several sequences, which might belong to novel bacteria or endogenous retroviruses, were identified. Taken together, the use of high-throughput sequencing technology in unveiling microbial metagenomics may facilitate future research in combating HIV/AIDS and its associated microbial complications.
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