Experimental evidence of the S state and fluorescence emission from the intramolecular charge transfer states in fucoxanthin.

Fucoxanthin is a typical carotenoid that absorbs light in the blue region of the visible spectrum, and its detailed electronic structures remain to be clarified. It is well known that carotenoids harvest energy from sunlight and transfer it to chlorophylls (Chls) and/or bacteriochlorophylls (BChls) through its excited states as the intermediate states; however, some excited states still need evidence to be definitely confirmed. Through steady-state fluorescence emission spectroscopy and femtosecond time-resolved fluorescence up-conversion technique, we provide new evidence for the identification of the excited S state in fucoxanthin, a representative of carotenoids.

Electronic properties, optical transparency and transport properties of the p-type transparent conductive oxide family SnPbNbO ( = 0, 0.5, 1.0, 1.5, and 2.0): a density functional theory study.

Based on density functional theory, we introduce a novel family of p-type transparent conductive oxides, SnPbNbO ( = 0, 0.5, 1.0, 1.

Compressed Sr superconducting transition temperature up to 17.65 K.

Due to the simplicity of their composition, the study of the superconducting properties of elemental substances holds significant importance for understanding the mechanisms of high-temperature superconductivity. This work involves simulated calculations to investigate the phase transition sequence and superconducting properties of Sr under pressure. The stability range of the Sr-IV phase 2/ was redefined, determining that it can extend up to 150 GPa, and the phase transition sequence of Sr under high pressure was studied.

Circulating inflammatory cytokines and sarcopenia-related traits: a mendelian randomization analysis.

Objective: To explore the causal relationships between 91 circulating inflammatory cytokines and sarcopenia-related traits (low hand grip strength, appendicular lean mass, and usual walking pace) by Mendelian randomized analysis.

Methods: Independent genetic variations of inflammatory cytokines and sarcopenia-related traits were selected as instrumental variables from publicly available genome-wide association studies (GWAS). The MR analysis was primarily conducted using the inverse variance-weighted (IVW) method.

Emerging superconductivity rules in rare-earth and alkaline-earth metal hydrides.

Hydrides of alkaline-earth and rare-earth metals have garnered significant interest in high-temperature superconductor research due to their excellent electron-phonon coupling and high upon pressurization. This study explores the electronic structures and electron-phonon coupling of metal hydrides XH ( = 4,6), where X includes Ca, Mg, Sc, and Y. The involvement of d-orbital electrons alters the Fermi surface, leading to saddle-point nesting and a charge density wave (CDW) phase transition, which opens the superconducting gap.

Association between relative grip strength and depression among U.S. middle-aged and older adults: results from the NHANES database.

Background: Mental health issues among middle-aged and older adults are gaining increasing attention. Recent studies have shown that relative grip strength is associated with cardiovascular diseases and various cancers, but its relationship with depression remains unclear.

Methods: This cross-sectional study included data from adults aged 50 years and older from the 2011-2014 National Health and Nutrition Examination Survey.

Predicting the thermal decomposition temperature of energetic materials from a simple model.

Context: The key factor in designing heat-resistant energetic materials is their thermal sensitivity. Further research and prediction of thermal sensitivity remains a great challenge for us. This study is based on first-principles calculations and establishes a theoretical model, which comprehensively considers band gap, density of states, and Young's modulus to obtain a empirical parameter Ψ.

Molecular Structures, Dipole Moments, and Electronic Properties of β-HMX under External Electric Field from First-Principles Calculations.

In order to investigate the impact of an external electric field on the sensitivity of β-HMX explosives, we employ first-principles calculations to determine the molecular structure, dipole moment, and electronic properties of both β-HMX crystals and individual β-HMX molecules under varying electric fields. When the external electric field is increasing along the [100], [010], and [001] crystallographic directions of β-HMX, the calculation results indicate that an increase in the bond length (N1-N3/N1'-N3') of the triggering bond, an increase in the main (N3, N3') value, an increase in the minimum surface electrostatic potential, and a decrease in band gap all contribute to a reduction in its stability. Among these directions, the [010] direction exhibits the highest sensitivity, which can be attributed to the significantly smaller effective mass along the [010] direction compared with the [001] and [100] directions.

Molecular dynamics simulation of sensitivity of HMX, FOX-7, and TATB crystals.

Methods: This study used molecular dynamics (MD) to simulate three materials (HMX, FOX-7, and TATB) under the NVT ensemble. Six temperatures (100 K, 200 K, 300 K, 400 K, 500 K, and 600 K) were simulated. In addition, the trigger bond lengths, energy bands, and density of states of three materials were obtained at different temperatures and compared with the calculated results at 0 K.

A Method for Predicting the Melting Temperature of Ionic Compounds.

Predicting the melting temperature of materials has always been a topic of great concern. This article proposes an alternative model for determining the melting temperature of materials based on the main idea of the Lindemann melting criterion combined with the first-principles calculations of density functional theory. To verify the accuracy of the melting model, this article selected typical ionic crystals of MgO and 10 alkali metal halides as the validation objects.

Structural, elastic, mechanical, electronic, and optical properties of cubic KPbO from first-principle study.

Context: Based on first principles, the structure, elasticity, mechanics, electronics, and optical properties of cubic KPbO were studied. The structural parameters calculated by this method are close to the previous theoretical results. The elastic constant, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and mechanical stability are studied, and it is shown that cubic KPbO is mechanically stable, isotropic, and brittleness.

The calculated electronic and optical properties of β-GaO based on the first principles.

Introduction: The electronic and optical properties of β-Ga2O3 have been investigated by CASTEP using first principles. It is found that β-Ga2O3 has an indirect band gap and the conduction band base is located at the Γ point. The stability of β-Ga2O3 is demonstrated by the calculation of elastic constants, and the ductility of β-Ga2O3 is demonstrated by the ratio of Poisson's ratio to shear modulus.

Probing into the theory of impact sensitivity: propelling the understanding of phonon-vibron coupling coefficients.

The determination of impact sensitivity of energetic materials traditionally relies on expensive and safety-challenged experimental means. This has instigated a shift towards scientific computations to gain insights into and predict the impact response of energetic materials. In this study, we refine the phonon-vibron coupling coefficients in energetic materials subjected to impact loading, building upon the foundation of the phonon up-pumping model.

Structural, electronic, and optical properties of three types CaN from first-principles study.

Context: To find the potential value of CaN in the field of optoelectronics, the physical properties of CaN will be analyzed. It can be concluded from the electronic properties that the Ca-N bonds of α-CaN are more stable than those of δ-CaN and ε-CaN. The dielectric function, reflectivity function, and absorption function of three types of CaN were accurately calculated, and it was concluded that α-CaN, δ-Ca3N, and ε-CaN have greater transmittance for visible light and exhibit optical transparency in the near-infrared frequency domain.

The structural and electronic properties of (001) surface of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with first-principles calculations.

Context: 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a typical insensitive energetic material. It can be used in explosive formulations, such as PBX-9502 and LX-17-0. TATB is an intriguing and unusual explosive for another reason: it crystallizes into a wide array of planar hydrogen bonds, forming a graphite-like layered structure.

Association of the visceral adiposity index with femur bone mineral density and osteoporosis among the U.S. older adults from NHANES 2005-2020: a cross-sectional study.

Background: The visceral adiposity index (VAI) is a marker of abdominal fat distribution and adipose tissue function. However, the association between VAI and femur bone mineral density (BMD) and osteoporosis is unclear among the U.S.

Theoretical study on the correlation between the structure, excess energy, surface energy, electronic structure, nitro charge, and friction sensitivity of ,'-dinitroethylenediamine (EDNA).

The sensitivity of energetic materials along different crystal directions is not the same and is anisotropic. In order to explore the difference in friction sensitivity of different surfaces, we calculated the structure, excess energy, surface energy, electronic structure, and the nitro group along (1 1 1), (1 1 0), (1 0 1), (0 1 1), (0 0 1), (0 1 0), and (1 0 0) surfaces of EDNA based on density functional theory. The analysis results showed that relative to other surfaces, the (0 0 1) surface has the shortest N-N average bond length, largest N-N average bond population, smallest excess energy and surface energy, widest band gap, and the largest nitro group charge value, which indicates that the (0 0 1) surface has the lowest friction sensitivity compared to other surfaces.

Composition and structural characteristics of compressed alkaline earth metal hydrides.

The metallization of alkaline earth metal hydrides offers a way to achieve near-room temperature superconductivity. In order to explore the metallization mechanism of these hydrides under pressure, a detailed understanding of the property changes of alkaline earth metal hydrides is required. Based on first-principles calculations, we have systematically investigated the dihydrides (XH, X = Be, Mg, Ca, Sr, Ba) and tetrahydrides (XH, X = Mg, Ca, Sr, Ba) of alkaline earth metals, respectively.