Reversible voltammetric response for a molecule containing four non-equivalent redox sites with application to cytochrome c3 of Desulfovibrio vulgaris, strain Miyazaki

The cyclic voltammetric and differential pulse polarographic behavior of cytochrome c₃ of Desulfovibrio vulgaris, strain Miyazaki, has been evaluated in terms of a model employing four reversible redox centers. Both types of experiments can be fit by digital simulations using the four standard potentials: E₁⁰=?0.467, E₂⁰=?0.519, E₃⁰=?0.539 and E₄⁰=?0.580 V vs. SCE. The results are interpreted to mean that the four redox centers are chemically different and only weakly interacting. The relationships between the observed macroscopic standard potentials and the microscopic standard potentials for reduction of individual sites are discussed.     

Multiplex amplified product-length polymorphism analysis for rapid detection of human mitochondrial DNA variations.

A number of mutations in coding and noncoding regions of mitochondrial DNA (mtDNA) have previously been studied. In the present study, we simultaneously typed six mutation sites in the coding region by use of amplified product-length polymorphism (APLP) analysis. The mtDNA variations of 2471 individuals from 20 populations of Japanese, Korean, Chinese, and German were examined and classified into 18 haplotypes. Two of these haplotypes, B1 (estimated ancestral haplotype) and C1, were distributed among all populations tested. However, the haplotypes A1, A2, B2, B3, and C2 were mostly restricted to the Mongoloid populations, whereas haplotypes B5 and C5 appeared almost exclusively in the German population. Phylogenetic analysis by the neighbor-joining method revealed that the Japanese populations were more closely related to each other than to the other East Asian populations surveyed. The multiplex APLP method is suitable for large-scale screening studies of mtDNA variability because it is both rapid and economical.     

Heat transfer enhancement in a turbulent natural convection boundary layer along a vertical flat plate

An experimental study on heat transfer enhancement for a turbulent natural convection boundary layer in air along a vertical flat plate has been performed by inserting a long flat plate in the spanwise direction (simple heat transfer promoter) and short flat plates aligned in the spanwise direction (split heat transfer promoter) with clearances into the near-wall region of the boundary layer. For a simple heat transfer promoter, the heat transfer coefficients increase by a peak value of approximately 37% in the downstream region of the promoter compared with those in the usual turbulent natural convection boundary layer. It is found from flow visualization and simultaneous measurements of the flow and thermal fields with hot- and cold-wires that such increase of heat transfer coefficients is mainly caused by the deflection of flows toward the outer region of the boundary layer and the invasion of low-temperature fluids from the outer region to the near-wall region with large-scale vortex motions riding out the promoter. However, heat transfer coefficients for a split heat transfer promoter exhibit an increase in peak value of approximately 60% in the downstream region of the promoter. Flow visualization and PIV measurements show that such remarkable heat transfer enhancement is attributed to longitudinal vortices generated by flows passing through the clearances of the promoter in addition to large-scale vortex motions riding out the promoter. Consequently, it is concluded that heat transfer enhancement of the turbulent natural convection boundary layer can be substantially achieved in a wide area of the turbulent natural convection boundary layer by employing multiple column split heat transfer promoters. It may be expected that the heat transfer enhancement in excess of approximately 40% can be accomplished by inserting such promoters.     

An Efficient Preparation and Structural Characterization of Sialylglycopeptides from Protease Treated Egg Yolk

Abstract

Delipidated egg yolk (DEY) was digested with protease. The digest was ultrafiltered using a molecular weight cut-off of 10,000, and the UF permeate was treated with a reverse osmosis membrane. The resulting sialylglycopeptides-rich fraction was purified by the combination of anion exchange and gel filtration chromatography. Two major sialylglycopeptides, A-I and A-II, were characterized as biantennary complex type sialylglycopeptides having one or two N-acetylneuraminic acid and 1 - 3.5 amino acids including one asparagine residue by composition analyses and ¹H NMR spectroscopy.     

Iridium(III) Catalysts with an Amide‐Pendant Cyclopentadienyl Ligand: Double Aromatic Homologation Reactions of Benzamides by Fourfold C−H Activation

The synthesis, characterization, and catalytic performance of iridium(III) catalysts that bear an amide‐pendant cyclopentadienyl ligand ([Cp^AIrI₂]₂) is reported. These [Cp^AIrI₂]₂ catalysts were obtained from the complexation of a Cp^A ligand precursor with [Ir(cod)OAc]₂ followed by oxidation. Double aromatic homologation reactions of benzamides with alkynes by fourfold C?H activation proceeded in good to high yield with these [Cp^AIrI₂]₂ catalysts, demonstrating their superior catalytic performance in this challenging transformation.     

Two‐step Synthesis of Multi‐Substituted Amines by Using an N‐Methoxy Group as a Reactivity Control Element

The development of a two‐step synthesis of multi‐substituted N‐methoxyamines from N‐methoxyamides is reported. Utilization of the N‐methoxy group as a reactivity control element was the key to success in this two‐step synthesis. The first reaction involves a N‐methoxyamide/aldehyde coupling reaction. Whereas ordinary amides cannot condense with aldehydes intermolecularly due to the poor nucleophilicity of the amide nitrogen, the N‐methoxy group enhances the nucleophilicity of the nitrogen, enabling the direct coupling reaction. The second reaction in the two‐step process was nucleophilic addition to the N‐methoxyamides. Incorporation of the N‐methoxy group into the amides increased the electrophilicity of the amide carbonyls and promoted the chelation effect. This nucleophilic addition enabled quick diversification of the products derived from the first step. The developed strategy was applicable to a variety of substrates, resulting in the elaboration of multi‐substituted piperidines and acyclic amines, as well as a substructure of a complex natural alkaloid.     

Products of idempotents in finite full transformation semigroups

Communicated by J. M. Howie     

Simultaneous analysis of carbamate pesticides in tap and raw water by LC/ESI/MS.

Ten carbamate pesticides including four suspected endocrine disruptors, methomyl, benomyl (carbendazim), aldicarb and carbaryl, were simultaneously analyzed by LC/ESI/MS. The influence of the matrix on the variation of the ion signal intensities of (M + H)+ and adduct ions was investigated. Although the intensities of three oxamyl ions changed depending on the matrix, the variation in the concentration calculation of oxamyl was reduced by using the sum total of the area value of two ions. The limits of the quantitation of ten pesticides without a concentration procedure were from 0.4 - 30 microg/l. The solid-phase recovery rates of ten pesticides spiked into tap water and raw water were in the range of 69-111%. Using this method, the concentrations of the pesticides in tap and raw water sampled at 14 monitoring points in Hyogo Prefecture were determined. Carbendazim in three raw water samples and carbofuran in one of these three samples were detected at low concentrations (less than 0.32 microg/l).