Structural predictions of three medium-sized thiolate-protected gold nanoclusters Au(SR), Au(SR), and Au(SR).

The knowledge of structural evolution among thiolate-protected gold nanoclusters is not only helpful for understanding their structure-property relationship but also provides scientific evidence to rule-guided structure predictions of gold nanoclusters. In this paper, three new atomic structures of medium-sized thiolate-protected gold nanoclusters, Au(SR), Au(SR), and Au(SR), are predicted based on the grand unified model and ring model. Two structural evolution rules, , Au(SR) + [Au(SR)] → Au(SR) + [Au(SR)] → Au(SR) and Au(SR) + [Au(SR)] → Au(SR) + [Au(SR)] → Au(SR) + [Au(SR)] → Au(SR), are explored.

Sound Absorption of the Absorber Composed of a Shunt Loudspeaker and Porous Materials in Tandem.

To investigate the sound absorption of the absorber composed of a shunt loudspeaker (SL) and porous materials (PM) in tandem, the normal absorption coefficients for six samples of different groups of parameters are measured using impedance tubes. It is shown that a composite structure consisting of a porous material, an air layer, a shunt loudspeaker, and an air layer arranged in sequence (PM + Air1 + SL + Air2) has the potential to achieve broadband sound absorption close to three octaves in the frequency range of 200-1600 Hz. To further explore the sound absorption mechanism of "PM + Air1 + SL + Air2", a theoretical model based on the transfer matrix method is established, and a numerical model is built in the pressure acoustic module using COMSOL Multi-physics field software.

Effects of Na+ and Cl- on hydrated clusters by ab initio study.

A comprehensive genetic algorithm is used to perform a global search for Cl-(H2O)1-9 and NaCl(H2O)1-9. The structural optimization, energy calculations, vibrational characteristics, and charge distribution were performed at an ab initio high-level theory. Combined with the calculation results of Na+(H2O)1-6 by Wang et al.

Comparative analysis of domestic and foreign coal mine safety supervision modes based on knowledge map.

In order to grasp the research status and hot frontier of coal mine safety supervision mode in the world in the past 40 years, this paper takes the relevant literature in the field of "coal mine safety" and "supervision" included in the core collection of Web of Science (WOS) and the core journals of CNKI as the data source; based on the methods of statistical analysis and bibliometrics, the visualization analysis software CiteSpace is used to draw the map of scientific knowledge. Through the visualization analysis of the main research institutions, countries, and authors in this field, the main research forces and the distribution of researchers in this field are described. Through the visualization analysis of key words and research clustering, the research hotspots and future development trends in this field are described.

Elemental dissolution characteristics of granite and gabbro under high-temperature water-rock interactions.

In the process of developing hot dry rock (HDR) through enhanced geothermal systems (EGS), it is necessary to inject circulating water to complete thermal energy extraction. However, the injected water will react with the high-temperature rock and produce mineral dissolution, which can destroy the artificial reservoir and affect the development of geothermal energy. To explore the influence of temperature on the solution composition and mineral dissolution after water-rock reaction, this study conducted water-rock interaction experiments on gabbro and granite at different heat treatment temperatures.

Comprehensive Study Addressing the Challenge of Efficient Electrocatalytic Biomass Upgrading of 5-(Hydroxymethyl)Furfural (HMF) with a CH NH Ionic Liquid on Metal-Embedded Mo B MBene Nanosheets.

Amine-containing derivatives are important intermediates in drug manufacturing; sustainable synthesis of amine compounds from green carbon-based biomass derivatives has attracted increasing attention, especially the reductive amination of biomass molecules via electrochemical upgrading. To achieve efficient reductive amination of 5-(hydroxymethyl)furfural (HMF) via electrocatalytic biomass upgrading, this work proposes a new HMF biomass upgrading strategy based on metal supported on Mo B MBene nanosheets using a density functional theory comprehensive study. HMF and methylamine (CH CH ) can be reduced to 5-(hydroxymethyl) aldiminefurfural (HMMAMF) via electrocatalytic biomass upgrading, which is identified as a promising technology to produce pharmaceutical intermediates.

Dynamic modeling and analysis of Hepatitis B epidemic with general incidence.

New stochastic and deterministic Hepatitis B epidemic models with general incidence are established to study the dynamics of Hepatitis B virus (HBV) epidemic transmission. Optimal control strategies are developed to control the spread of HBV in the population. In this regard, we first calculate the basic reproduction number and the equilibrium points of the deterministic Hepatitis B model.

Association between sleep quality and psychological symptoms: A cross-sectional survey of Chinese university students performed during the COVID-19 pandemic.

Background: Since the start of the coronavirus 2019 pandemic, people have faced many challenges, including in relation to sleep quality and psychological health. This study aims to analyze the association between sleep quality and psychological symptoms among university students in China, and to provide reference data to facilitate the development of interventions to improve the physical and mental health of university students.

Methods: A stratified cluster sampling method was used to investigate the sleep quality and psychological symptoms of 6,363 university students in China.

Controlling strong-field fragments of HD with a synthesized two-color laser pulse.

The possibility of controlling fragment branching in the dissociation and ionization channels of HD is theoretically explored by synthesized intense fields using 790 nm and 395 nm pulses. In the control scheme, the branching ratios of the fragments to different channels (H + D, D + H and H + D) are manipulated by regulating the relative phase and intensity between the 790 nm and 395 nm pulses. Altering the relative phase can induce constructive or destructive interference between the net two photon process and the direct one photon process, and the highest modulation reaches 80% between the two dissociation fragments (H + D and D + H).

Multiphoton Ionization Reduction of Atoms in Two-Color Femtosecond Laser Fields.

We report the ionization reduction of atoms in two-color femtosecond laser fields in this joint theoretical-experimental study. For the multiphoton ionization of atoms using a 400 nm laser pulse, the ionization probability is reduced if another relatively weak 800 nm laser pulse is overlapped. Such ionization reduction consistently occurs regardless of the relative phase between the two pulses.

Electrochemically Oxidative Phosphating of Aldehydes and Ketones.

Disclosed herein is the first protocol for the electrochemically oxidative phosphating of aldehydes and ketones to generate α-hydroxyphosphine oxides with diphenylphosphine as the phosphine source. Various phosphating products containing P-C bonds are basically assembled in modest to excellent yields. This electrochemical phosphating was achieved by utilizing a simple undivided cell with foam nickel electrodes at room temperature without the addition of any oxidant or metal catalyst.

Dirichlet problems of fractional p-Laplacian equation with impulsive effects.

The purpose of the article is to investigate Dirichlet boundary-value problems of the fractional p-Laplacian equation with impulsive effects. By using the Nehari manifold method, mountain pass theorem and three critical points theorem, some new results are achieved under more general growth conditions. In addition, this paper weakens the commonly used p-suplinear and p-sublinear growth conditions.

A periodic boundary value problem of fractional differential equation involving p(t)-Laplacian operator.

The purpose of this article is to research the existence of solutions for fractional periodic boundary value problems with p(t)-Laplacian operator. In this regard, the article needs to establish a continuation theorem corresponding to the above problem. By applying the continuation theorem, a new existence result for the problem is obtained, which enriches existing literature.

Research on coal mine safety management based on digital twin.

Coal mine safety management is the foundation and decisive factor of coal mining. The manual detection model is the main way for traditional coal mine safety management, which has problems such as inefficient identification of safety risks in coal mines, poor control accuracy and slow response measures and so on. Therefore, to make up for the shortcomings in the traditional coal mine safety management model, this paper introduces digital twin technology into coal mine safety management to achieve intelligent and efficient management of coal mine safety accidents.

Association between Dairy Consumption and Psychological Symptoms: Evidence from a Cross-Sectional Study of College Students in the Yangtze River Delta Region of China.

Background: Assessing the dairy consumption and psychological symptoms of Chinese college students as a reference for the mental health of Chinese college students.

Methods: A three-stage stratified whole-group sampling method was used to investigate dairy consumption and psychological symptoms among 5904 (2554 male students, accounting for 43.3% of the sample) college students in the Yangtze River Delta region.

Controlling the Nonlinear Optical Behavior and Structural Transformation with A-Site Cation in α-AZnPO (A = Li, K).

Regulating the crystal structure by A-site cation substitution is one of the effective methods to explore high-performance nonlinear optical (NLO) materials. Herein, two non-centrosymmetric (NCS) compounds, α-MZnPO (M = Li, K) with short UV absorption edges 221 and 225 nm, are obtained by performing A-site cation substitution method. It is noteworthy that α-LiZnPO (α-LZPO) achieves >10 times second harmonic generation (SHG) response (2.

On the Consensus Performance of Multi-Layered MASs with Various Graph Parameters-From the Perspective of Cardinalities of Vertex Sets.

This work studies the first-order coherence of noisy multi-agent networks with multi-layered structures. The coherence, which is a sort of performance index of networks, can be seen as a sort of measurement for a system's robustness. Graph operations are applied to design the novel multi-layered networks, and a graph spectrum approach, along with analysis methods, is applied to derive the mathematical expression of the coherence, and the corresponding asymptotic results on the performance index have been obtained.

Metal -free PhI(OAc)-oxidized decarboxylation of propiolic acids towards synthesis of α-acetoxy ketones and insights into general decarboxylation with DFT calculations.

A metal-free oxidative decarboxylation reaction of propiolic acids mediated by hypervalent iodine(III) reagents is described. This decarboxylative C-O bond-forming reaction used a combination of (diacetoxyiodo)benzene and aromatic, heteroaromatic or aliphatic propiolic acids to give the corresponding α-acetoxy ketones. Preliminary mechanistic studies based on both DFT calculations and high-resolution mass spectroscopy (HRMS) suggested that the reaction proceeded through decarboxylation to form a propargyl iodide intermediate.

Influence of Microstructure on Dynamic Mechanical Behavior and Damage Evolution of Frozen-Thawed Sandstone Using Computed Tomography.

Frost-induced microstructure degradation of rocks is one of the main reasons for the changes in their dynamic mechanical behavior in cold environments. To this end, computed tomography (CT) was performed to quantify the changes in the microstructure of yellow sandstone after freeze-thaw (F-T) action. On this basis, the influence of the microscopic parameters on the dynamic mechanical behavior was studied.

Polyhalogenation-Facilitated Spirolactonization at the -Position of Phenols.

A novel dearomative spirolactonization/polyhalogenation of phenols that employs hypervalent iodine PhICl (iodobenzene dichloride) as both an oxidant and chlorine source with an indispensable base, or only using NBS (-bromosuccinimide) without any additives, is presented. Halide participations are a vital factor in the cascade reaction of 3'-hydroxy-[1,1'-biphenyl]-2-carboxylic acids with good selectivities and reactivities and induced the rapid constructions of multiple C-halogen bonds and directional C═O bonds in a one-step operation under mild conditions. In gaining a good understanding of the mechanism, the increase in number of bromine atoms was inferred rationally from the spirolactonization process, assisted by DFT calculations and high-resolution mass spectrometry.

Relationship between body mass index and physical fitness index in Chinese college students: Results from a cross-sectional survey.

Background: To explore the cross-sectional relationship between the body mass index (BMI) and physical fitness index (PFI) of Chinese college students.

Methods: In total, 30 497 (male 16 197, 55.5%) Chinese college students aged 19-22 were tested for height, weight and five physical fitness indicators (50-m sprint, sit and reach, standing long jump, 1000/800-m run, pull-up/bent-leg sit-up).

Effect of Different Solvents on Morphology and Gas-Sensitive Properties of Grinding-Assisted Liquid-Phase-Exfoliated MoS Nanosheets.

Grinding-assisted liquid-phase exfoliation is a widely used method for the preparation of two-dimensional nanomaterials. In this study, N-methylpyrrolidone and acetonitrile, two common grinding solvents, were used during the liquid-phase exfoliation for the preparation of MoS nanosheets. The morphology and structure of MoS nanosheets were analyzed via scanning electron microscopy, X-ray diffraction, and Raman spectroscopy.

Electrocatalytic Biomass Upgrading of Furfural using Transition-Metal Borides via Density Functional Theory Investigation.

Electrocatalytic biomass upgrading has proven to be an effective technique for generating value-added products. Herein, the design and development of furfural upgrading using transition-metal borides (MBenes) with simultaneous production of hydrogen are presented. Using density functional theory, the stabilities, selectivities, and activities of 13 MBene candidates are systematically evaluated for furfural upgrading.

Compared with dietary behavior and physical activity risk, sedentary behavior risk is an important factor in overweight and obesity: evidence from a study of children and adolescents aged 13-18 years in Xinjiang, China.

Background: Malnutrition or insufficient physical activity (PA) is a risk factor for obesity and chronic disease in children and adolescents. Affected by different economic circumstance, ethnic, dietary behavior, physical activity and other factors, children and adolescents in Xinjiang, China are facing a severe situation of overweight and obesity prevention and control. It is necessary to analyze the dietary behavior and physical activity of children and adolescents with different nutritional status and the relationship between them.

Synthesis of fluorinated polycyclic dehydroaltenusin analogs through hypervalent iodine-catalyzed dearomatization.

We developed a method employing stoichiometric -chloroperbenzoic acid (-CPBA) as an oxidant and hydrogen fluoride pyridine (pyr·HF) as a fluoride source with catalytic amounts of iodobenzene (PhI) for the cyclization and fluorination-dearomatization of phenols, leading to a range of fluorocyclohexa-dienones with yields of up to 94%. This reaction provides a convenient method to synthesize fluorine-containing dehydroaltenusin analogs under mild conditions, and without expensive reagents. These analogs have potential application as inhibitors of DNA polymerase.