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Turbulence in the atmospheric surface layer, especially in deserts and semi-arid regions, significantly affects sand movement. In unstable stratification, turbulence exhibits complex intermittency, complicating its impact on saltation. This study uses wavelet transform analysis to examine the effects of turbulence intermittency in unstable stratification on saltation. Our analysis reveals that in unstable stratification, the energy distribution of turbulence is more dispersed, the intermittent characteristics are more significant, and the intermittent burst duration of streamwise turbulence is longer, while the vertical intermittent burst duration is shorter. The fitting formulas of the energy ratio and stratification stability of the streamwise wind speed, vertical wind speed, and temperature at different frequencies are given. In addition, there is a complex nonlinear relationship between stratification stability and friction velocity on saltation. In unstable stratification, the critical wind speed required for saltation is higher than that of near-neutral, and the jumping speed and horizontal transport are weakened. Moreover, the coherence between wind speed and saltation flux increases significantly at low frequency with the increase in instability, indicating that large-scale motion plays a key role in saltation under these conditions. The more unstable the stratification is, the more obvious the phase difference fluctuation of the low frequency part is, and the more unfavorable the formation of stable saltation sand conditions. This study reveals the turbulence intermittently and its complex effects on sand particle movement in unstable stratification, which is of great significance for predicting and controlling dust storms, land desertification, and soil erosion. [ABSTRACT FROM AUTHOR]

Glycerol-3-phosphoacyltransferase (GPAT) is an important rate-limiting enzyme in the biosynthesis of triacylglycerol (TAG), which is of great significance for plant growth, development, and response to abiotic stress. Although the characteristics of GPAT have been studied in many model plants, little is known about its expression profile and function in barley, especially under abiotic stress. In this study, 22 GPAT genes were identified in the barley genome and divided into three groups (I, II, III), with the latter Group III subdivided further into three subgroups based on the phylogenetic analysis. The analyses of conserved motifs, gene structures, and the three-dimensional structure of HvGPAT proteins also support this classification. Through evolutionary analysis, we determined that HvGPATs in Group I were the earliest to diverge during 268.65 MYA, and the differentiation of other HvGPATs emerged during 86.83–169.84 MYA. The tissue expression profile showed that 22 HvGPAT genes were almost not expressed in INF1 (inflorescence 1). Many functional elements related to stress responses and hormones in cis-element analysis, as well as qRT-PCR results, confirm that these HvGPAT genes were involved in abiotic stress responses. The expression level of HvGPAT18 was significantly increased under abiotic stress and its subcellular localization indicated its function in the endoplasmic reticulum. Various physiological traits under abiotic stress were evaluated using transgenic Arabidopsis to gain further insight into the role of HvGPAT18, and it was found that transgenic seedlings have stronger resistance under abiotic stress than to the wild-type (WT) plants. Overall, our results provide new insights into the evolution and function of the barley GPAT gene family and enable us to explore the molecular mechanism of functional diversity behind the evolutionary history of these genes. [ABSTRACT FROM AUTHOR]

High energy materials based on fused ring are an important type of new energetic materials recently synthesized. However, its decomposition path has not received much attention. Density functional theory (DFT) method is used to study the initial decomposition reaction paths of 12 high energy materials based on fused ring. In addition to the conventional decomposition reaction, it is also found that the production of N2 molecule by ring opening process, which is the lowest energy initial decomposition path with only 40 kcal/mol energy barrier among [5,6,5]‐tricyclic heterocyclic energetic materials and also theoretically shows that such reactants are the most unstable and conform to the experimental data. In addition, it is also found that there is a novel reaction path for releasing N2 by contraction of middle ring in the initial decomposition path of [5,7,5]‐tricyclic and [5,8,5]‐tricyclic heterocyclic energetic materials. [ABSTRACT FROM AUTHOR]

FOX‐7 is a typical high‐energy and low‐sensitivity material. Due to the unique "push‐pull" nitroenamine structure, abundant derivatives with good performance can be synthesized. DFT method is used to study the synthesis mechanism for two FOX‐7 amino‐substituted derivatives. The synthesis mechanism of amino‐substituted derivative MTNzA is cyclization followed by isomerization, which is different from the pathway of isomerization followed by cyclization proposed by previous authors. Carbohydrazide is tend reacted with two FOX‐7 to produce BADCh, rather than ring formation with one FOX‐7. [ABSTRACT FROM AUTHOR]

We performed DFT/TDDFT investigation on the sensing mechanism of the D–π–A type fluorescence probes 4-(5-R-thiophen-2-yl)-2-isobutyl-2H-[1,2,3]triazolo[4,5-e][1,2,4] triazolo[1,5-a]pyrimidines (ITTP1, ITTP2, ITTP3), which are designed for detecting 2,4,6-trinitrophenol (TNP) explosive. Theoretical calculations reveal that the fluorescence sensing mechanism was induced by the combination of the π–π stacking interaction and photo-induced electron transfer. The blueshift in the UV–Vis spectrum of the ITTP sensors was correlated with the decrease in electron-donating ability of the molecule probes and was further evidenced by the calculated 1H NMR spectra and DCT index. The roles of the weak interactions: π–π stacking and hydrogen-bonding interaction for the probes fluorescence sensing process were analyzed, and the π–π stacking interaction was verified to be the dominant for the fluorescence sensing. The present finding should be useful for the future design of explosive fluorescent probes and the interpretation of the sensing mechanisms. [ABSTRACT FROM AUTHOR]