Synthesis of heavily substituted 1,2-amino alcohols in enantiomerically pure form

[reaction: see text] A simple and convenient methodology for the preparation of optically pure 2-amino-2-aryl-1,1-diphenylethanols is presented. Allylamine was found to produce the ring-opening of triaryloxiranes in a regioselective and a stereospecific fashion. Removal of the allyl protecting group provided the free 1,2-amino alcohols in enantiomerically pure form.     

Recent applications of conductivity detection in capillary and chip electrophoresis

The review provides a comprehensive survey of the recent applications of contact and contactless conductivity detection in capillary electrophoretic and chip electrophoretic analyses of a broad scale of compounds, from low-molecular-mass highly mobile small inorganic and organic ions, via medium-molecular-mass peptides and oligo- and polynucleotides up to high-molecular-mass biopolymers, proteins and nucleic acids fragments. The review presents also the recent developments in the construction of different types of conductivity detectors (detectors with galvanic contact of the sensing electrodes with the BGE and sample components, contactless conductivity detectors with capacitively coupled tubular and semitubular electrodes and combined conductivity/optical detectors) applied in the capillary electromigration methods performed in classical fused silica, polytetrafluorethylene, and polyetheretherketone capillaries or on glass and polymethylmethacrylate microchips. In addition, the principle and theoretical bases of conductivity detection in capillary electromigration techniques, zone electrophoresis, ITP, micellar EKC, and electrochromatography are briefly described.     

Gas-phase structures, rotational barriers, and conformational properties of hydroxyl and mercapto derivatives of cyclohexa-2,5-dienone and cyclohexa-2,5-dienthione

The rotational barriers and conformational properties of the hydroxyl and mercapto groups attached to the alpha and beta positions of cyclohexa-2,5-dione and cyclohexa-2,5-dienthione have been studied at the B3LYP/ 6-311++G(d,p) level of theory. The results show that the conformational preferences of these studied systems are the result of a subtle interplay between different competing effects (conjugation, hyperconjugation, and steric repulsions). The applicability of the density functional theory reactivity indices and the maximum hardness principle for the present systems has been analyzed.     

An extension of Fujita’s non-extendability theorem for Grassmannians

In this paper we study smooth complex projective varieties X containing a Grassmannian of lines ${{\mathbb G}(1, r)}$ which appears as the zero locus of a section of a rank two nef vector bundle E. Among other things we prove that the bundle E cannot be ample.     

Genome size,self‐organization and DNA's dark matter

Chromosomes exhibit several features indicating that its spatiotemporal dynamics is self‐organized. It has been recently suggested that a negative correlation between genome size and mean chromosome number would also be a fingerprint of selforganization, related to how human language is organized at the level of words and syllables. However, the vast dominance of non‐coding DNA in eukaryotic genomes should prevent an interpretation of genome/chromosome size based on functional trade‐offs related to information storage and transmission. Moreover, the reported negative correlation is shown to be an inevitable consequence of the definitions of chromosome and genome length and it is thus unrelated to any type of special generative process. © 2010 Wiley Periodicals, Inc. Complexity 16: 20–23, 2010     

Science at the Hard X-ray Diffraction Limit (XDL2011), Part 1

There is growing excitement in the synchrotron materials science community about the potential of nearly diffraction-limited, high-repetition rate, hard X-ray sources, such as an Energy Recovery Linac (ERL) or an Ultimate Storage Ring (USR), and that these sources will pave the way to scientific insights and discoveries not possible with existing facilities. These future sources will deliver highly coherent, nearly diffraction-limited X-ray beams that will power ultra-intense, nanometer-scale X-ray probes and imaging capabilities approaching atomic resolution. They will produce X-ray pulses at MHz to GHz repetition rates and span pulse durations from below 50 femtoseconds to tens of picoseconds, enabling new classes of experiments in hard X-ray science.     

Dual Wavelength Spectrophotometry. Determination of 1,2,4-Benzenetricarboxylic Acid and Benzenepentacarboxylic Acid

Dual wavelength ultraviolet spectrophotometry was utilized for the determination of 1,2,4-benzenetricarboxylic and benzenepentacarboxylic acids in their simultaneous solution.