Computational Study of Structure and Reactivity of Oligomeric Vanadia Clusters Supported on Anatase and Rutile TiO₂ Surfaces

We use density functional theory to examine structure–activity relationships of small vanadia clusters supported on anatase TiO₂(001) and rutile TiO₂(110) surfaces. A thermodynamic analysis indicates that the vanadia monomer cluster can be stabilized on the anatase TiO₂(001) surface in a catalytically relevant oxygen environment. On the other hand, vanadia clusters tend to aggregate into dimers on the rutile TiO₂(110) surface because this surface binds the monomer less strongly as compared to anatase. Hydrogen adsorption is found to be exothermic on the vanadia monomer adsorbed on both supports, enhanced by a charge transfer between the adsorbate and the substrate. There is no such charge transfer on vanadia dimers and tetramers, where the hydrogen adsorption energies are similar to that on the single crystal V₂O₅(001) surface. The improved catalytic performance of the anatase support can be attributed to the ability of this surface to stabilize the catalytically active vanadia monomer clusters

Data_Sheet_1_The association between sedentary behavioral characteristics and poor vision among Chinese children and adolescents.pdf

IntroductionTo understand the features of sedentary behavior of Chinese children and adolescents and its relationship with poor visual acuity, a self-administered “Questionnaire on Sedentary Behavior of Children and Adolescents” was used to survey 4,203 students in grades 4–12 in six administrative regions of China.Results(1) The average time spent in sedentary behaviors (SB) of Chinese children and adolescents was about 8.1 h per day, of which the academic sedentary time was the longest, accounting for 79.2% of total sedentary time. The total time spent on SB and the time spent on studying SB were more in the upper grades and less in screen SB and cultural leisure SB, respectively. There were significant sex differences in total SB time (p ConclusionThere were significant grade, sex, and regional differences in the SB of Chinese children and adolescents, and sedentary time was strongly related to the prevalence of poor vision detection rate.</p

real ice accumulation

the excel for velocity and ice thickness analysis <br><br

Adsorption and Separation Mechanism of Thiophene/Benzene in MFI Zeolite: A GCMC Study

Selective removal of thiophene from aromatic components is one of the key challenges facing the petrochemical industry. The adsorption and separation mechanism from the molecular viewpoint can guide and upgrade the relative adsorption based technology. Therefore, we performed the grand canonical ensemble Monte Carlo (GCMC) simulation to investigate the adsorption performance and mechanism of competitive adsorption. Density distribution and radial distribution functions (RDF) analysis give a more detailed description of the adsorption sites. For pure component adsorption, donut-shaped adsorption sites were obtained for both benzene and thiophene from the straight channel point. From the viewpoint of the zigzag channel, the sorbates follow the straight line shape distribution at low loading and the S shape distribution at high loading. As for the binary component adsorption, more benzene adsorbs in the zeolite than thiophene at low pressure; however, thiophene competes successfully at high pressure. This can be explained by the key factor: at low pressure, the size effect plays an important role. While the pressure increases, the interaction energy dominates the process. Analyzing RDFs of the binary adsorption, we observed that when benzene competes with thiophene, the preferential adsorption sites do not change; however, the emergence possibility of benzene gets smaller

Heavy-Metal Adsorption Behavior of Two-Dimensional Alkalization-Intercalated MXene by First-Principles Calculations

The two-dimensional (2D) layered MXene (Ti₃C₂(OH)_<i>x</i>F_2–<i>x</i>) material can be alkalization intercalated to achieve heavy-metal ion adsorption. Herein the adsorption kinetics of heavy-metal ions and the effect of intercalated sites on adsorption have been interpreted by first-principles with density functional theory. When the coverage of the heavy-metal ion is larger than 1/9 monolayer, the two-dimensional alkalization-intercalated MXene (alk-MXene: Ti₃C₂(OH)₂) exhibits strong heavy-metal ion absorbability. The hydrogen atoms around the adsorbed heavy-metal atom are prone to form a hydrogen potential trap, maintaining charge equilibrium. In addition, the ion adsorption efficiency of alk-MXene decreases due to the occupation of the F atom but accelerates by the intercalation of Li, Na, and K atoms. More importantly, the hydroxyl site vertical to the titanium atom shows a stronger trend of removing the metal ion than other positions

Variance partitioning ratio of individual traits studied across five ecological scales.

<p>(a) shoot height; (b) branch length; (c) root/shoot ratio; (d) leaf number. Open part of the columns corresponds to environmental variances, and grey part to ontogenetic variances.</p

Summary of SMA regression parameters (<i>n</i>, <i>p</i>, <i>r</i>², α, β, 95%CI, respectively) for allometric relationships between plant functional traits (shoot height, root/shoot ratio, branch length and leaf number) and plant size of the macrophyte species <i>Potamogeton maackianus</i> across transects of two lakes: e1, e2, e3 in Erhai Lake and n1, n2, n3, n4 in Niushanhu Lake.

<p><i>n</i>, samples number; <i>r</i>², correlation coefficient; <i>p</i>-values refer to correlation analyses following standardized major axes (SMA) procedures (see the Material and Methods section); α, slope; CIα, 95% CIs of the slope; β, intercept; CIβ, 95% CIs of the intercept;</p>*<p>: <i>p</i><0.05; **: <i>p</i><0.01; ***: <i>p</i><0.001.</p

Box-plots of the four traits along water depth gradient in two lakes.

<p>(a, b) shoot height; (c, d) root/shoot ratio; (e, f) total branch length; (g, h) total leaf number. Open box indicates the data in Erhai and grey box indicates the data in Niushanhu. The median values are represented by the empty cycle, quartiles (25 and 75% percentiles) by boxes with error bars. Extreme data values are plotted with individual markers.</p

Allometric relationships between traits and total biomass for all individuals in two lakes.

<p>(a) shoot height; (b) branch length; (c) root/shoot ratio; (d) leaf number. Open cycle indicates the data in Erhai and closed cycle indicates the data in Niushanhu. Variables were log₁₀-transformed prior to model fitting.</p