ABSTRACT
First-principles molecular dynamics has been used to investigate the structural, vibrational, and energetic properties of formic acid, formic acid-formate anion dimers, and liquid formic acid in a periodically repeated box with 32 formic acid molecules. We found that in liquid formic acid the hydrogen-bonded clusters mainly consist of linear branching chains. From our simulation, we got good agreement with the available structural and dynamical data. We also studied the proton transfer in the cis-formic acid-formate anion dimer, and we showed that this proton transfer does not have any potential barrier. The hydrogen bonding statistics as well as the mean lifetime of the hydrogen bonds are analyzed.
Subject(s)
Computer Simulation , Formates/chemistry , Solvents/chemistry , Anions , Dimerization , Hydrogen/chemistry , Hydrogen Bonding , Isomerism , Molecular Conformation , Oxygen/chemistry , Protons , Spectrum Analysis , Time FactorsABSTRACT
A microchamber was developed for the examination of biological specimens in nearly natural environments, in an electron microscope, at 70kV accelerating voltage.. The chamber can be supplied continually with the sample and with the reagents, which makes it suitable for the study of biochemical reactions, too. Temperature and vapour pressure in the chamber can be controlled and the thickness of the specimen can be varied. Transmission electron micrographs of biological specimens, such as human blood cells, bull gametes and Bacillus subtilis have been obtained. Mobility of microorganisms, which is regarded as a criterion of the wet state, has been observed.
