Complete minimal submanifolds of compact Lie groups

We give a new method for manufacturing complete minimal submanifolds of compact Lie groups and their homogeneous quotient spaces. For this we make use of harmonic morphisms and basic representation theory of Lie groups. We then employ our method to construct many examples of compact minimal submanifolds of the special unitary groups.     

Ultrafast Multidimensional Laplace NMR Using a Single‐Sided Magnet

Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single‐ and multidimensional LNMR experiments, based on spatial encoding, are viable with low‐field, single‐sided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments, and increases the sensitivity per unit time by a factor of three. The reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by orders of magnitude, allowed by single‐scan approach.     

An efficient algorithm for solving nonlinear equations with a minimal number of trial vectors: applications to atomic-orbital based coupled-cluster theory

The conjugate residual with optimal trial vectors (CROP) algorithm is developed. In this algorithm, the optimal trial vectors of the iterations are used as basis vectors in the iterative subspace. For linear equations and nonlinear equations with a small-to-medium nonlinearity, the iterative subspace may be truncated to a three-dimensional subspace with no or little loss of convergence rate, and the norm of the residual decreases in each iteration. The efficiency of the algorithm is demonstrated by solving the equations of coupled-cluster theory with single and double excitations in the atomic orbital basis. By performing calculations on H(2)O with various bond lengths, the algorithm is tested for varying degrees of nonlinearity. In general, the CROP algorithm with a three-dimensional subspace exhibits fast and stable convergence and outperforms the standard direct inversion in iterative subspace method.     

Chirality transfer. A stereospecific palladium salt catalyzed phenylation of chiral butenols.

(R)-(|) and (S)-(+)-3-phenyl butanones have been obtained by a 20% stereospecific palladium catalyzed β-phenylation of the corresponding chiral butenols, the catalyst acting preferentially, through an alkoxide complex, by one face of the alcohol double bond, e.g. the si face of (R)-(|)3-butene-2-ol(I).     

Thermodynamics of aqueous solutions of methyldiethanolamine and diisopropanolamine

The vapour–liquid equilibrium (VLE) of the systems of water + methyldiethanolamine (MDEA) and water + diisopropanolamine (DIPA) was measured at several temperatures with a static total pressure apparatus. The solid–liquid equilibrium (SLE) of the same systems was measured at low amine concentrations by means of two experimental methods: a visual method and a Differential Scanning Calorimeter (DSC). The activity coefficients of water + MDEA were modelled with the NRTL equations. The model parameters were regressed from VLE, SLE and excess enthalpy data from this work and from the literature. The model developed in this work was compared with models found in the literature. The NRTL equations were also used to model the activity coefficients of the system of water + DIPA. The model parameters were fitted from the VLE and SLE data measured in this work.     

Environmental and food analysis by desorption atmospheric pressure photoionization‐mass spectrometry

Desorption atmospheric pressure photoionization‐mass spectrometry (DAPPI‐MS) is a versatile surface analysis technique for a wide range of analytes, especially for neutral and non‐polar analytes. Here, a set of analytes typically found in environmental or food samples was analyzed by DAPPI‐MS. The set included five polyaromatic hydrocarbons (PAHs), one N‐PAH, one brominated flame retardant, and nine pesticides, which were studied with three different spray solvents: acetone and toluene in positive ion mode, and anisole in negative ion mode. The analytes showed [M + H]⁺, M^+?, and [M–H]^? ions as well as fragmentation and substitution products. Detection limits for the studied compounds ranged from 30 pg to 1 ng (from 0.14 to 5.6 pmol). To demonstrate the feasibility of the use of DAPPI‐MS two authentic samples – a circuit board and orange peel – and a spiked soil sample were analyzed. Tetrabromobisphenol A, imazalil, and PAHs were observed from the three above‐mentioned samples, respectively. The method is best suited for rapid screening analysis of environmental or food samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Interpretation of orientational contrast in STM images of GaAs(1 1 0) cleavage surface

The electronic structure of GaAs(1 1 0) surface is analyzed using Density Functional Theory (DFT-GGA) in atomic orbital basis (LCAO). The surface orbitals and the corresponding local density of electronic states (LDOS) are calculated for purposes of interpreting STM images. We show how local atomic orbitals of surface atoms are related to tunneling channels for electrons in STM imaging. A destructive interference between orbitals of two neighbouring atoms increases the contrast between the two atoms, and this is reflected in directionality of STM patterns of GaAs(1 1 0) surfaces. We also discuss how the basic formalism of Tersoff-Hamann approach to STM simulation can be reformulated to reveal the role of phase difference between tunneling channels.