Engineering electronic structure of atomically thin two-dimensional (2D) materials is of great importance to their potential applications. In comparison to numerous other approaches, such as strain ...and chemical functionization, alloying can continuously tune the band gaps in a wide energy range. Atomically thin 2D alloys have been prepared and studied recently due to their potential use in electronic and optoelectronic applications. In this review, we first summarize the preparation methods of 2D alloys (mainly on transition metal dichalcogenide (TMD) monolayer alloys), including mechanical exfoliation, physical vapor deposition (PVD), chemical vapor deposition (CVD) and chalcogen exchange. Then, atomic-resolution imaging, Raman and photoluminescence (PL) spectroscopy characterization of 2D alloys are reviewed, in which band gap tuning is discussed in detail based on the PL experiments and theoretical calculations. Finally, applications of 2D alloys in field-effect transistors (FETs), photocurrent generation and hydrogen evolution catalysis are reviewed.
Alloying allows broad band gap engineering and more for two-dimensional materials.
The business case for investing in online reputation has received increasing scrutiny in recent years. This study identifies the business value of consumer reviews and management responses to hotel ...performance. We present a panel data analysis of online consumer reviews and management responses of 843 hotels on a hotel review website. The results show that overall rating, attribute ratings of purchase value, location and cleanliness, variation and volume of consumer reviews, and the number of management responses are significantly associated with hotel performance. In addition, variation and volume of consumer reviews moderate the relationship between overall rating and hotel performance. Management responses, together with variation and volume of consumer reviews, moderate the relationship between certain attribute ratings and hotel performance. Implications of utilizing consumer reviews and management responses to leverage hotel business are provided.
The outbreak of Corona Virus Disease-2019 (COVID-19) has posed unprecedented pressure and threats to healthcare workers in Wuhan and the entire country.
To assess the effect of the COVID-19 outbreak ...on the sleep quality of healthcare workers in a children's healthcare centre in Wuhan.
A cross-sectional, anonymized, self-reported questionnaire survey was conducted at the Children's Healthcare Centre of Renmin Hospital, Wuhan University, Wuhan, China. The questionnaire consisted of three parts, including socio-demographic characteristics and COVID-19 epidemic-related factors, the Pittsburgh sleep quality index (PSQI), and Zung's self-rating anxiety scale (SAS) and self-rating depression scale (SDS).
In total, 47 out of 123 (38%) participants with PSQI scores > 7 were identified as having sleep disturbance. A logistic regression analysis showed that sleep disturbance was independently associated with being an only child (adjusted odds ratio (OR) and 95% confidence interval (CI) 3.40 (1.21-9.57), P < 0.05), exposure to COVID-19 patients (adjusted OR and 95% CI 2.97 (1.08-8.18), P < 0.05) and depression (adjusted OR and 95% CI 2.83 (1.10-7.27), P < 0.05).
We observed that, during the outbreak of COVID-19, sleep disturbance was highly prevalent among paediatric healthcare workers, and sleep disturbance was independently associated with being an only child, exposure to COVID-19 patients and depression. Therefore, more mental health services are required for front-line paediatric healthcare workers in Wuhan.
A rock mechanics test system and the acoustic emission (AE) test system were employed to perform experiments on bedded rock salt samples under uniaxial compression and indirect tension. Based on the ...basic theory of fractal geometry, a column covering method is proposed to analyze the fractal property of the spatial distribution of acoustic emissions during the rock damage and failure process. The experimental results indicate obvious differences in failure features for different parts of a sample due to the structural differences in bedded rock salt. The consistency between the failure state and the AE spatial distribution is confirmed. The relationships of the stress and energy release with the fractal dimension of the AE spatial distribution are established. An increase in the fractal dimension corresponds to a decrease in the stress and an increase in the energy release, which is consistent with the theoretical analysis. When the fractal dimension obtained from uniaxial compression and indirect tensile tests is less than 2.20 and 2.57, respectively, the stresses in the bedded rock salt sample are over 80% of the peak stress. A great amount of accumulated damage occurs, leading to the global failure of the bedded rock salt sample. Therefore, it is possible to forecast the failure state of bedded rock salt by inspecting the variation between the stress or the energy release and the fractal dimension of the AE spatial distribution.
► Column-covering fractal method for AE spatial distribution was proposed. ► AE signals under different loading conditions were monitored for bedded rock salt. ► Fractal properties of bedded rock salt were studied by the fractal method proposed. ► Relationships between fractal dimensions and energy or stress were obtained.
In the present study, a consortium of two rhizobacteria Bacillus amyloliquefaciens Bk7 and Brevibacillus laterosporus B4, termed 'BB', biochemical elicitors salicylic acid and β-aminobutyric acid ...(SB) and their mixture (BBSB) were investigated for cold and drought stress tolerance in rice plants. After withholding water for 16 days, rice plants treated with BBSB showed 100% survival, improved seedling height (35.4 cm), shoot number (6.12), and showed minimum symptoms of chlorosis (19%), wilting (4%), necrosis (6%) and rolling of leaves. Similarly, BB inoculation enhanced plant growth and reduced overall symptoms in rice seedlings subjected to 0 ± 5 °C for 24 h. Our results imply several mechanisms underlying BB- and BBSB-elicited stress tolerance. In contrast to the control, both treatments significantly decreased leaf monodehydroascorbate (MDA) content and electrolyte leakage, and increased leaf proline and cholorophyll content. Moreover, activities of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) increased 3.0- and 3.6-fold, respectively. Moreover, expression of OsMYB3R-2, OsDIL, OsDREB1A and OsCDPK13 genes was significantly up-regulated, suggesting that these genes play important roles in abiotic stress tolerance of rice. In addition, bacterial strains Bk7 and B4 were able to produce high amounts of IAA and siderophores, and colonise the plant roots, while only strain Bk7 exhibited the capability to form biofilms and solubilise inorganic phosphate. This study indicates that the BB and BBSB bio-formulations can be used to confer induced systematic tolerance and improve the health of rice plants subject to chilling and drought stress.
How much information can be carried over a wireless network with a multiplicity of nodes, and how should the nodes cooperate to transfer information? To study these questions, we formulate a model of ...wireless networks that particularly takes into account the distances between nodes, and the resulting attenuation of radio signals, and study a performance measure that weights information by the distance over which it is transported. Consider a network with the following features. I) n nodes located on a plane, with minimum separation distance /spl rho//sub min/>0. II) A simplistic model of signal attenuation e/sup -/spl gamma//spl rho///spl rho//sup /spl delta// over a distance /spl rho/, where /spl gamma//spl ges/0 is the absorption constant (usually positive, unless over a vacuum), and /spl delta/>0 is the path loss exponent. III) All receptions subject to additive Gaussian noise of variance /spl sigma//sup 2/. The performance measure we mainly, but not exclusively, study is the transport capacity C/sub T/:=sup/spl Sigma/on/sub /spl lscr/=1//sup m/R/sub /spl lscr///spl middot//spl rho//sub /spl lscr//, where the supremum is taken over m, and vectors (R/sub 1/,R/sub 2/,...,R/sub m/) of feasible rates for m source-destination pairs, and /spl rho//sub /spl lscr// is the distance between the /spl lscr/th source and its destination. It is the supremum distance-weighted sum of rates that the wireless network can deliver. We show that there is a dichotomy between the cases of relatively high and relatively low attenuation. When /spl gamma/>0 or /spl delta/>3, the relatively high attenuation case, the transport capacity is bounded by a constant multiple of the sum of the transmit powers of the nodes in the network. However, when /spl gamma/=0 and /spl delta/<3/2, the low-attenuation case, we show that there exist networks that can provide unbounded transport capacity for fixed total power, yielding zero energy priced communication. Examples show that nodes can profitably cooperate over large distances using coherence and multiuser estimation when the attenuation is low. These results are established by developing a coding scheme and an achievable rate for Gaussian multiple-relay channels, a result that may be of interest in its own right.
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