Measurements of the oxygen K-edge X-ray absorption spectrum (XAS) of aqueous sodium halide solutions demonstrate that ions significantly perturb the electronic structure of adjacent water molecules. The addition of halide salts to water engenders an increase in the preedge intensity and a decrease in the postedge intensity of the XAS, analogous to those observed when increasing the temperature of pure water. The main-edge feature exhibits unique behavior and becomes more intense when salt is added. Density functional theory calculations of the XAS indicate that the observed red shift of the water transitions as a function of salt concentration arises from a strong, direct perturbation of the unoccupied molecular orbitals on water by anions, and does not require significant distortion of the hydrogen bond network beyond the first solvation shell. This contrasts the temperature-dependent spectral variations, which result primarily from intensity changes of specific transitions due to geometric rearrangement of the hydrogen bond network.
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http://dx.doi.org/10.1021/jp0445324 | DOI Listing |
Mikrochim Acta
January 2025
School of Public Health, Hebei Key Laboratory of Occupational Health and Safety for Coal Industry, North China University of Science and Technology, No. 21 Bohai Road, Caofeidian, Tangshan, 063210, Hebei, China.
Biochars (BCs) derived from waste-branches of apple tree, grape tree, and oak were developed for direct solid-phase extraction (SPE) of five benzodiazepines (BZDs) in crude urine samples prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination. Scanning electron microscopy, elemental analyzer, X-ray diffractometry, N adsorption/desorption experiments, and Fourier transform infrared spectrometry characterizations revealed the existence of their mesoporous structure and numerous oxygen-containing functional groups. The obtained BCs not only possessed high affinity towards BZDs via π-π and hydrogen bond interactions, but also afforded the great biocompatibility of excluding interfering components from undiluted urine samples when using SPE adsorbents.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Departamento de Física Aplicada - Instituto de Ciencia de Materiales, Matter at High Pressure (MALTA) Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr Moliner 50, Burjassot, 46100, Valencia, Spain.
The production of hydrogen (H) fuel through electrocatalysis is emerging as a sustainable alternative to conventional and environmentally harmful energy sources. However, the discovery of cost-effective and efficient materials for this purpose remains a significant challenge. In this study, we explore the potential of the transition-metal-substituted YNS MXene as a promising candidate for hydrogen production through the hydrogen evolution reaction (HER).
View Article and Find Full Text PDFLab Chip
January 2025
Department of Life Science and Technology, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8501, Japan.
DNA methylation is a crucial epigenetic modification used as a biomarker for early cancer progression. However, existing methods for DNA methylation analysis are complex, time-consuming, and prone to DNA degradation. This work demonstrates selective capture of unmethylated DNAs using ZnO nanowires without chemical or biological modifications, thereby concentrating methylated DNA, particularly those with high methylation levels that can predict cancer risk.
View Article and Find Full Text PDFChemistry
January 2025
East China University of Science and Technology, School of Material Science & Engineering, P.O. Box 289, 130 Meilong Rd., 200237, Shanghai, CHINA.
Silicon/carbon (Si/C) materials have achieved commercial applications as a solution to the problems of large volume expansion and short lifespan of silicon-based anodes in lithium-ion batteries. However, the potential risk of structural fracture and localized differences in surface adsorption properties lead to difficulties in maintaining the structural integrity of Si/C anodes using conventional binders during repeated lithiation/delithiation. Herein, an aqueous binder (PVA-g-M) based on polyvinyl alcohol (PVA) grafted methacrylic acid (MAA) obtained by self-emulsifyingemulsion polymerization is reported.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
National Key Laboratory of Scattering and Radiation, Beijing 100854, China.
The disordered assembly and low conductivity of carbon nanotubes are the main problems that limit the application of electromagnetic interference (EMI) shielding. In this work, an ordered lamellar assembly structure of multiwalled carbon nanotube/TiCT (MWCNT/TiCT) hybrid films was achieved by vacuum-assisted filtration through the hybridization of TiCT nanosheets and carbon nanotubes, where carbon nanotubes were tightly sticking on the surface of TiCT nanosheets via physical adsorption and hydrogen bonding. Compared with the pure carbon nanotubes films, the hybrid MWCNT/TiCT films achieved a significant improvement in conductivity of 452.
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