Flow-injection responses of diffusion processes and chemical reactions

Abstract

The technique of¯ow-injection analysis (FIA), now 25 years old, oers unique analytical methods that are fast, reliable and consume an absolute minimum of chemicals. These advantages together with its inherent feasibility for automation warrant the future application of FIA as an attractive tool of automated analytical chemistry. The need for an even lower consumption of chemicals and for computer analysis has motivated a study of the FIA peak itself, i.e., a theoretical model that provides detailed knowledge of the FIA pro®le was developed. It was shown that thē ow in a FIA manifold may be characterised by a diusion coecient that depends on the¯ow rate, denoted as the kinematic diusion coecient. The description was applied to systems involving species of chromium, both in the case of simple diusion and in the case of chemical reaction. It is suggested that the description may be used in the resolution of FIA pro®les to obtain information about the content of interferences, in the study of chemical reaction kinetics and to measure absolute concentrations within the FIA-detector cell.

A theoretical study of the molecular structure and torsional potential of styrene

“…Extension to the MP2/6-311++G** level [12] changed the dihedral angle to 33 • and the barriers to 0.6 and 2.0 kcal mol −1 , respectively. In this study [11], density functional theory (DFT) [13][14][15][16][17][18][19] was also applied but lead to a planar structure for the global minimum. The disagreement between MP2 and DFT results for this system was also confirmed in the context of a large study of conjugated systems [12].…”

Large valley splitting induced by spin–orbit coupling effects in monolayer W2NSCl

“…In this work, structural optimization and electronic structure calculations are performed using the Perdew-Burke-Ernzerhof (PBE) 24 functional within the framework of generalized gradient approximation (GGA) based on density functional theory (DFT), 25,26 as in the Vienna Ab Initio Computational Simulation Package (VASP). [27][28][29] The strong-correlated correction to the d electrons is taken into account by the GGA+U method, with parameters U and J being set in a way that the effective U eff = (U À J) = 4.59 eV for the 4d orbitals of the W atom.…”

Ultrahigh conductivity and antifreezing zwitterionic sulfobetaine hydrogel electrolyte for low-temperature resistance flexible supercapacitors

“…The harmonic frequency calculations were carried out at the same level of theory to help verify that all the structures had no imaginary frequency. 32,76…”

“…The harmonic frequency calculations were carried out at the same level of theory to help verify that all the structures had no imaginary frequency. 32,76 The interaction energy of the four possible interaction patterns of the molecules was calculated by the following equation:…”