Soliton model for the dielectric permeability of some quasi one-dimensional charge transfer salts

The dielectric permeability of bound soliton antisoliton pairs is considered. The model yields and explanation for the anomanously large dielectric constant, the conductivity at microwave frequencies and their low temperature behaviour observed in some quasi one-dimensional organic charge transfer.     

Magnetic scattering of spin polarized carriers in (In, Mn)Sb dilute magnetic semiconductor

Magnetoresistance measurements on the magnetic semiconductor (In, Mn)Sb suggest that magnetic scattering in this material is dominated by isolated Mn2+ ions located outside the ferromagnetically ordered regions when the system is below T(c). A model is proposed, based on the p-d exchange between spin-polarized charge carriers and localized Mn2+ ions, which accounts for the observed behavior both below and above the ferromagnetic phase transition. The suggested picture is further verified by high-pressure experiments, in which the degree of magnetic interaction can be varied in a controlled way.     

Investigation of chiral reactions: the structural detection of new hydrogenated isocinchona alkaloids from mixtures without isolation using electrospray ionization tandem mass spectrometry

The reaction mixture for the hydrogenation of ethyl pyruvate on Pt-alumina catalyst modified with isocinchona alkaloids (alpha-ICN (I) and beta-ICN (II)) was studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS). It was established that part of the chiral modifiers themselves are converted into ions of m/z 299, 305 and 309 in the course of chiral hydrogenation. The experimental data allowed the determination of the probable structure of the ions mentioned. According to ESI-MS/MS spectra the structure of the new cinchona alkaloids was assumed: tetrahydro-isocinchonines (III-VI), decahydro-isocinchonines (VII, VIII) and hydrogenated compounds of VII and VIII by scission of their C--N and C--O bonds (IX/1, IX/2, X). Fragmentation pathways are proposed for these new compounds.     

Cost reduction of high-order coupled-cluster methods via active-space and orbital transformation techniques

We discuss several techniques which have the potential to decrease the computational expenses of high-order coupled-cluster (CC) methods with a reasonable loss in accuracy. In particular, the CC singles, doubles, and triples (CCSDT) as well as the CC singles, doubles, triples, and perturbative quadruples [CCSDT(Q)] methods are considered, which are frequently used in high-precision model chemistries for the calculation of iterative triples and quadruples corrections. First, we study the possibilities for using active spaces to decrease the computational costs. In this case, an active space is defined and some indices of cluster amplitudes are restricted to be in the space. Second, the application of transformed virtual orbitals is investigated. In this framework, to reduce the computation time the dimension of the properly transformed virtual one-particle space is truncated. We have found that the orbital transformation techniques outperform the active-space approaches. Using the transformation techniques, the computational time can be reduced in average by an order of magnitude without significant loss in accuracy. It is demonstrated that high-order CC calculations are possible for considerably larger systems than before using the implemented techniques.     

An existence result for a nonhomogeneous problem in R2 related to nonlinear Hencky-type materials

This paper investigates a nonlinear and non-homogeneous system of partial differential equations. The motivation comes from the fact that in a particular case the problem discussed here can be used in modeling the behavior of nonlinear Hencky-type materials. The main result of the paper establishes the existence of a nontrivial solution in an adequate functional space of Orlicz–Sobolev type by using Schauder’s fixed point theorem combined with adequate variational techniques.     

Palladium nanoparticles on modified cellulose as a novel catalyst for low temperature gas reactions

Cellulose - Palladium was incorporated into carboxymethylated cellulose fibers as a support, thereby becoming an efficient and stable catalyst for low temperature gas phase reaction. Thus, NO was...     

Synthesis of three regioisomers of the pentasaccharide part of the Skp1 glycoprotein of Dictyostelium discoideum

Three regioisomers of the linear pentasaccharide part of the Skp1 glycoprotein, found in Dictyostelium discoideum, were prepared in the form of (2-trimethylsilyl)ethyl glycosides by means of 2+3 block syntheses using the disaccharide donor at the non-reducing end, and three different trisaccharide acceptors at the reducing end. Fucosylation of (2-trimethylsilyl)ethyl 3,4,6-tri-O-benzyl-β-d-galactopyranosyl-(1→3)-4,6-O-benzylidene-2-deoxy-2-NPhth-β-d-glucopyranoside with different fucosyl donors carrying an O-(2-naphthyl)methyl ether as a temporary-protecting group at positions C2, C3 or C4 gave rise to the protected core trisaccharides. After selective removal of the (2-naphthyl)methyl group, the resulting acceptors were glycosylated with the α(1→6) linked digalactosyl donor to yield the respective three regioisomeric pentasaccharides. Transformation of the phthalimido moiety into an N-acetyl group, followed by catalytic hydrogenation of the reducible-protecting groups furnished the free target pentasaccharides, which should be able to assist during the elucidation of the exact structure of the natural pentasaccharide.     

Determination of <Superscript>93</Superscript>Zr in nuclear power plant wastes

A radioanalytical method (based on separation using UTEVA columns and ICP-MS measurement) has been used for determination of ⁹³Zr in 37 nuclear power plant samples. As ⁹³Nb might affect the detection of ⁹³Zr, Monte Carlo activation model was used to calculate the expected ⁹³Zr/^natZr mass ratio, which was compared to measured ones. It was found, that a decontamination factor of 10³ is sufficient to get a measurement uncertainty of less than 10%.     

General implementation of the relativistic coupled-cluster method

We report the development of a general order relativistic coupled-cluster (CC) code. Our implementation is based on Kramers-paired molecular spinors, utilizes double group symmetry, and is applicable with the full Dirac-Coulomb and several approximate relativistic Hamiltonians. The available methods include iterative and perturbative single-reference CC approaches with arbitrary excitations as well as a state-selective multi-reference CC ansatz. To illustrate the performance of the new code, benchmark calculations have been performed for the total energies, bond lengths, and vibrational frequencies of the monoxides of Group IVa elements. The trends due to the simultaneous inclusion of relativity as well as higher-order electron correlation effects are analyzed. The newly developed code significantly widens the scope of the ab initio relativistic calculations, for both molecules and atoms alike, surpassing the accuracy and reliability of the currently available implementations in the literature.     

High-accuracy theoretical study on the thermochemistry of several formaldehyde derivatives

In the case of several formaldehyde derivatives, with importance in atmospheric and combustion chemistry, the currently available thermochemical values suffer from considerably large uncertainties. In this study a high-accuracy theoretical model chemistry has been used to provide accurate thermochemical data including heats of formation at 0 and 298 K and standard molar entropies at 298 K for CF(2)O, FCO, HFCO, HClCO, FClCO, HOCO, and NH(2)CO. For most of the thermochemical quantities studied here, this investigation delivers the best available estimate.