Optimization of background electrolyte composition for simultaneous contactless conductivity and fluorescence detection in capillary electrophoresis of biological samples

In this article, optimization of BGE for simultaneous separation of inorganic ions, organic acids, and glutathione using dual C⁴D‐LIF detection in capillary electrophoresis is presented. The optimized BGE consisted of 30 mM 2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]ethanesulfonic acid, 15 mM 2‐amino‐2‐hydroxymethyl‐propane‐1,3‐diol, and 2 mM 18‐crown‐6 at pH 7.2 and allowed simultaneous separation of ten inorganic anions and cations, three organic acids and glutathione in 20 min. The samples were injected hydrodynamically from both capillary ends using the double‐opposite end injection principle. Sensitive detection of anions, cations, and organic acids with micromolar LODs using C⁴D and simultaneously glutathione with nanomolar LODs using LIF was achieved in a single run. The developed BGE may be useful in analyses of biological samples containing analytes with differing concentrations of several orders of magnitude that is not possible with single detection mode.     

Microscopic Elucidation of Solid‐Electrolyte Interphase (SEI) Film Formation via Atomistic Reaction Simulations: Importance of Functional Groups of Electrolyte and Intact Additive Molecules

Secondary batteries such as Li‐ion battery are expected to be utilized as not only ubiquitous electric power sources such as mobile phones but also large‐scale electricity storage devices. Therefore, it is urgent to develop the higher performance secondary batteries. Their lifetime and stability are found to be strongly dependent on the nature of passivation film called solid electrolyte interphase (SEI) film formed on the anode surface in the initial charge‐discharge cycle. However, since it is difficult to directly observe the film formation processes in experiment, its microscopic mechanism is still not found. On the other hand, although the theoretical methods are useful complement to the experiment, some new methodologies are necessary to understand the long‐term processes of SEI film, which is produced as a result of that a lot of chemical reactions proceed simultaneously. Under the circumstances, we have developed Red Moon method that can simulate such complex chemical reaction systems, and were able to analyze for the first time the SEI film formation processes on the anode surface at the atomistic level. Then, we clarified theoretically the microscopic mechanism of the additive effect which is essential to improve the Na‐ion battery performance so as to enhance the SEI film formation. This new microscopic insight must provide an important guiding principle for use in designing the most suitable electrolytes for developing high‐performance secondary batteries.     

De-excitation process and hot luminescence in the FA(type I) center in KCl:Na

The de-excitation process of F_A(type I) centers in KCl:Na has been investigated by measuring the hot luminescence spectrum from optically excited F_A centers with time-resolved spectroscopy. The experimental results are analyzed by using a model that describes a time evolution of the phonon wave packet during the vibronic relaxation process from the Franck-Condon state to a relaxed excited state. From the analysis of the experimental data, information on the vibronic mixing between 2p and 2s states, whose magnitude varies during the relaxation process, and the adiabatic potential energy curves of 2s and 2p states are extracted. The present results are compared with the already known ones of the F_A(type II) centers.     

Zirconia-based planar NO2 sensor using ultrathin NiO or laminated NiO–Au sensing electrode

The nanostructured thin NiO films with the thicknesses of 30–180 nm were examined as a sensing electrode (SE) for the planar mixed-potential-type yttria-stabilized zirconia (YSZ)-based NO₂ sensor. The sensing characteristics were examined in the temperature range of 600–800 °C under the wet condition (5 vol.% water vapor). Among the NiO-SEs tested, the 60 nm-thick NiO-SE sintered at 1,000 °C was found to give the highest NO₂ sensitivity in the NO₂ concentration range of 50–400 ppm accompanying with fast response/recovery at the operating temperatures of 600–700 °C. The high NO₂ sensitivity was attributed to the high catalytic activity for both electrochemical reactions of O₂ and NO₂ at the interface of NiO-SE/YSZ. The ultrathin gold layer with the thickness of about 60 nm was additionally formed on the 60 nm-thick NiO-SE to fabricate the laminated-type (60 nm NiO/60 nm Au)-SE. It was demonstrated that the use of this laminated (NiO–Au)-SE improved both the sensitivity and the selectivity to NO₂.     

Photochemical reaction of silyl-substituted 1,4-disila(dewar-benzene) with isocyanide and phenylacetylene

The irradiation of silyl-substituted 1,4-disila(Dewar-benzene) 1 with light of wavelength λ > 320 nm in the presence of 2,6-dimethylphenyl-isocyanide or phenylacetylene produced 1,4-bis(di-tert-butylmethylsilyl)-2,3,5,6-tetraethyl-7-(2,6-dime-thylphenylimino)-1,4-disilabicyclo[2.2.1]hepta-2,5-diene 5 or 1,4-bis(di-tert-butylmethylsilyl)-2,3,5,6-tetraethyl-1-(2-phenylethynyl)-1,4-disilacyclohexa-2,5-diene 6 , respectively. The molecular structures of 5 and 6 were determined by spectroscopic data and X-ray crystallography. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:87–92, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20411     

Highly Enantioselective Reactions of Configurationally Labile Epimeric Diamine Complexes of Lithiated S‐Benzyl Thiocarbamates

Substitution reactions that employ primary‐carbamoyl‐protected arylmethanethiols are described. The enantiodetermining step was found to occur in the post‐deprotonation step as a dynamic thermodynamic resolution with a chiral bis(oxazoline) ligand. The configurationally labile lithium complexes were trapped with various electrophiles to yield different substitution products in good to excellent yields and enantiomeric excesses. The absolute configurations of the substitution products were determined, and the stereochemical pathway of the substitution reaction was elucidated for different classes of electrophiles. The temperature‐dependent epimerization process was monitored by ¹H and ⁶Li NMR spectroscopy.     

Enzyme catalytic membrane based on a hybrid mesoporous membrane

Immobilization of glucose oxidase (GOD) within a hybrid mesoporous membrane with 12 nm pore diameter was successfully achieved, resulting in catalytically high efficiency during flow of a glucose solution across the membrane.     

Freeze-thaw behaviour of aqueous glucose solutions--the crystallisation of cubic ice

We report on the polymorphic transitions of ice in aqueous solutions of glucose during freezing and thawing over a temperature range of 298-153 K. Emphasis is placed on the sub-glass temperature range where the systems consist of cubic ice (ice-1c) crystals embedded in a freeze concentrated, vitrified glucose solution. The systems were studied by a combination of thermal, cryomicroscopic and X-ray diffraction techniques. At the glass transition (230 K) the solution phase contained 80 mol% of unfrozen water which, on further cooling, was shown to crystallise as cubic ice (ice-1c), nucleated in the vitrified matrix. The thermal stability of the ice-1c formed was studied by annealing and isothermal changes in the diffraction patterns with time. The polymorphic transition 1c --> 1h could be fitted to first order kinetics. Contrary to currently held belief, this study has provided evidence that ice-1c can be formed directly in the bulk water phase of a vitrified solution.     

HELFIT: Helix fitting by a total least squares method

The problem of fitting a helix to data arises in analysis of protein structure, in nuclear physics, and in engineering. A continuous helix is described by five parameters: helix axis, helix radius, and helix pitch. One of these helix parameters is frequently predefined in the helix fitting. Other algorithms find only the helix axis or determine separately the helix axis, the helix radius, or the helix pitch. Here we describe a total least squares method, HELFIT, for helix fitting. HELFIT enables one to calculate simultaneously all five of the helix parameters with high accuracy. The minimum number of data points required for the analysis is only four. HELFIT is very insensitive to noise even in short helices. HELFIT also calculates a parameter, p = rmsd/(N − 1)^1/2, which estimates the regularity of helical structures independent of the number of data points, where rmsd is the root mean square distance from the best-fit helix to data points and N is the number of data points. It should become a basic tool of structural bioinformatics.