The nature of the chemical bond is important in all natural sciences, ranging from biology to chemistry, physics and materials science. The atomic force microscope (AFM) allows to put a single chemical bond on the test bench, probing its strength and angular dependence. We review experimental AFM data, covering precise studies of van-der-Waals-, covalent-, ionic-, metallic- and hydrogen bonds as well as bonds between artificial and natural atoms. Further, we discuss some of the density functional theory calculations that are related to the experimental studies of the chemical bonds. A description of frequency modulation AFM, the most precise AFM method, discusses some of the experimental challenges in measuring bonding forces. In frequency modulation AFM, forces between the tip of an oscillating cantilever change its frequency. Initially, cantilevers were made mainly from silicon. Most of the high precision measurements of bonding strengths by AFM became possible with a technology transfer from the quartz watch technology to AFM by using quartz-based cantilevers ("qPlus force sensors"), briefly described here.
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http://dx.doi.org/10.3390/molecules26134068 | DOI Listing |
Nat Chem Biol
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View Article and Find Full Text PDFEMBO J
January 2025
Institute of Cancer Research, Shenzhen Bay Laboratory, Shenzhen, Guangdong, 518107, China.
Ferroptosis, an iron-dependent form of programmed cell death characterized by excessive lipid hydroperoxides accumulation, emerges as a promising target in cancer therapy. Among the solute carrier (SLC) superfamily, the cystine/glutamate transporter system antiporter components SLC3A2 and SLC7A11 are known to regulate ferroptosis by facilitating cystine import for ferroptosis inhibition. However, the contribution of additional SLC superfamily members to ferroptosis remains poorly understood.
View Article and Find Full Text PDFSci Rep
January 2025
School of Safety Science and Engineering (School of Emergency Management), Nanjing University of Science and Technology, Nanjing, 210094, People's Republic of China.
Powder-based fire extinguishing agents have become a kind of promising substitutes for halon extinguishing agents in civil aircrafts. However, their storage lifespan, significantly influenced by the thermal aging, emerges as a crucial yet overlooked aspect for aviation use. This study investigates the effects of thermal aging cycles on various parameters of ordinary dry powder extinguishing agent (ODPEA) and novel superhydrophobic and oleophobic ultra-fine dry powder extinguishing agent (SHOU DPEA), including surface microscopic morphology, D90 (the diameter at which 90% of the cumulative volume of particles are equal to or smaller than this value), chemical structure, hydrophobic and oleophobic angles, flowability, extinguishing time and effectiveness.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, 11461, Riyadh, Saudi Arabia.
Quantitative structure-property relationship (QSPR) modeling has emerged as a pivotal tool in the field of medicinal chemistry and drug design, offering a predictive framework for understanding the correlation between chemical structure and physicochemical properties. Topological indices are mathematical descriptors derived from the molecular graphs that capture structural features and connectivity, playing a crucial role in QSPR analysis by quantitatively relating chemical structures to their physicochemical properties and biological activities. Lung cancer is characterized by its aggressive nature and late-stage diagnosis, often limiting treatment options and significantly impacting patient survival rates.
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
January 2025
Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Madrid, Spain.
Pollution is one of the main factors that threaten biodiversity nowadays. Plastic waste is a global problem which impacts not only on the marine environment but also on the terrestrial one. Great amounts of this kind of refuse are compiled in landfills, where lots of avian species feed.
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