Adsorption and Gas-Sensing Properties of Agn (n = 1–4) Cluster Doped GeSe for CH4 and CO Gases in Oil-Immersed Transformer

The adsorption mechanism of CO and CH4 on GeSe, modified with the most stable 1–4 Ag-atom clusters, is studied with the help of density functional theory. Adsorption distance, adsorption energy, total density of states (TDOS), projected density of states (PDOS), and molecular orbital theory were all used to analyze the results. CO was found to chemisorb exothermically on GeSe, independent of Ag cluster size, with Ag4-GeSe representing the optimum choice for CO gas sensors. CH4, in contrast, was found to chemisorb on Ag-GeSe and Ag2-GeSe and to physisorb on Ag3-GeSe and Ag4-GeSe. Here, Ag GeSe was found to be the optimum choice for CH4 gas sensors. Overall, our calculations suggest that GeSe modified by Ag clusters of different sizes could be used to advantage to detect CO and CH4 gas in ambient air

Parallel hierarchical clustering using weighted confidence affinity

There have been many attempts for clustering categorical data such as market basket dataset. However, most of categorical clustering approaches belong to partitional clustering which requires at least one input parameter (e.g., the minimum intra-cluster similarity or the desired number of clusters). In this paper, we propose a parallelised hierarchical clustering approach for categorical data (PH-clustering) using vertical data structures. In order to minimise the impact of low support items, we devise a weighted confidence (WC) affinity function to compute the similarity between clusters. Based on our analysis of the major clustering steps, we adopt a partial local and partial global approach to reduce computation time as well as to keep network communication at minimum. Load balance issues are addressed especially during the data partitioning phase. Our experimental results on standardised market basket data show that the proposed weighted confidence affinity measure is more accurate than other contemporary affinity measures in the literature and that our parallel clustering approach provides magnitudes of time improvements over sequential clustering especially over larger data sizes. Our results also indicate that the number of items/attributes in the dataset has a more drastic impact on performance than the number of transactions/tuples

Gas-Sensing Property of TM-MoTe2 Monolayer towards SO2, SOF2, and HF Gases

Detecting the characteristic decomposition products (SO2, SOF2, and HF) of SF6 is an effective way to diagnose the electric discharge in SF6-insulated equipment. Based on first-principles calculations, Au, Ag, and Cu were chosen as the surface modification transition metal to improve the adsorption and gas-sensing properties of MoTe2 monolayer towards SO2, SOF2, and HF gases. The results show that Au, Ag, and Cu atoms tend to be trapped by TH sites on the MoTe2 monolayer, and the binding strength increases in the order of Ag < Au < Cu. In gas adsorption, the moderate adsorption energy provides the basis that the TM-MoTe2 monolayer can be used as gas-sensing material for SO2, SOF2, and HF. The conductivity of the adsorption system changes significantly. The conductivity decreases upon gases adsorption on TM-MoTe2 monolayer, except the conductivity of Ag-MoTe2 monolayer increases after interacting with SOF2 gas

Prevalence and Associated Factors of Weight Management among 18-79 Years Old in Beijing

Background Weight management should be extended to the entire population and not limited to special populations. Exploring the willingness, status, measures and influencing factors of adults' weight management, may contribute to the development of a reasonable, scientific, and easily operable method for reaching or maintaining a healthy weight. Objective To understand the prevalence and associated factors regarding achieving or maintaining a healthy weight in residents aged 18-79 in Beijing. Methods A survey was conducted from August to December 2017 with a stratified multistage sample of 13 188 permanent residents aged 18-79 from Beijing's 16 districts using a self-compiled questionnaire for understanding their self-assessed weight, weight changes within the past 12 months, and use of methods for weight control. The prevalence of weight management was compared by different characteristics. Methods for weight management used by weight controllers were comparatively analyzed by sex and age. We explored the differences in daily dietary habits and physical activity between weight controllers and non-weight controllers. Multivariate Logistic regression was used to analyze the factors associated with the implementation of weight management. Results The overall prevalence of weight management in the residents over the last 12 months was 29.90% (3 947/13 188) . The prevalence of weight management differed statistically by sex, marital status, level of education, diabetes prevalence, current smoking status, physical activity status, voluntary health check-ups, assessment of weight, change in weight over the past 12 months, and BMI (P<0.05) . Diet control〔87.31% (3 446/3 947) 〕 and physical exercise〔78.34% (3 092/3 947) 〕were the most widely used weight management methods. The proportion of men who used physical exercise and smoking for weight control was significantly higher than that of women (P<0.001) , whereas the proportion of women who used diet control and weight loss medications for weight control was significantly higher than that of men (P<0.05) . The proportion of residents who used physical exercise and smoking for weight control was differed statistically by age groups (P<0.05) . 2 668 cases (67.60%) used both diet control and physical exercise to control weight, among whom 60-70 year olds accounted for a higher percentage than did 18-44 year olds and 45-59 year olds (P<0.001) . 625 cases (15.83%) relied only on diet control to control weight, among whom 18-44 year olds accounted for a higher percentage than did 45-59 year olds and 60-79 year olds (P<0.001) . The prevalence of weight management by physical activity or smoking differed significantly across age groups. Compared with non-weight controllers, weight controllers had lower prevalence of inadequate intake of fresh fruit and vegetables and excessive intake of red meat (P<0.05) . Moreover, they had higher prevalence of doing ≥ 150 min of moderate to vigorous intensity activities per week (P<0.001) . Furthermore, they had higher prevalence of spending ≥4 hours per day in leisure-time sedentary behaviors (P<0.001) . Multivariate regression analysis showed that age<60 years, women, married/unmarried cohabitation, higher level of education (junior high school and above) , current non-smoking, alcohol consumption within the past 7 days, physical inactivity, voluntary physical examinations, correctly assessing one's own weight, weight gain/loss ≥ 2.5 kg in the past 12 months, and having a BMI within the range of normal to obesity were associated with higher possibility of implementing weight management (P<0.05) . Conclusion In these Beijing residents aged 18-79 years, diet control and increased exercise were popular for weight control, but the use of unhealthy weight management methods was also found. When guiding residents to use proper methods to control weight, individualized management programs should be developed with sex, age, education level and other factors taken into consideration

Structural Core-Shell beyond Chemical Homogeneity in Non-Stoichiometric Cu5FeS4 Nano-Icosahedrons: An in Situ Heating TEM Study

Thermal stability of core-shell structured nanoparticles is of vital importance to their practical applications at elevated temperature. Understanding the evolution of chemical distribution and the crystal structure of core-shell nanostructures with temperature variation at the nanoscale will open the route for practical applications and property enhancement of nanoparticles through proper design of new nanomaterials. In this study, core-shell non-stoichiometric Cu5FeS4 icosahedral nanoparticles were investigated by in situ heating transmission electron microscopy. Compared to the high structural and compositional stability at room temperature, the interdiffusion of Cu and Fe atoms became significant, ending up with disappearance of chemical difference in the core and shell over 300 °C. In contrast, different crystal structures of the core and shell were preserved even after heating at 350 °C, indicating the high structural stability. The inconsistency between chemical composition and crystal structure should be ascribed to the interaction between the intrinsic strain existing in the icosahedrons and various structures of this material system. In other words, the geometrically intrinsic strain of the nano-icosahedrons is helpful to modulate/maintain the core-shell structure. These findings open new opportunities for revealing the thermal stability of core-shell nanostructures for various applications and are helpful for the controllable design of new core-shell nanostructures