Linear rheology of compressible soft nanocomposites

The influences of interfacial tension and compressibility to the linear viscoelastic properties of nanocomposite and nanoporous materials are considered theoretically. The effective bulk and shear moduli of the systems are calculated within the generalized composite sphere model which takes into account the effect of interfacial tension. It is found that frequency dependence of the effective dynamic shear and bulk moduli of nanocomposites with the compressible elastic matrix and viscous inclusions may be represented in terms of the Zener model comprising of the viscoelastic Kelvin element in series with the elastic spring. The relations of the Zener model parameters with the material characteristics are revealed. The physical interpretation of the frequency behavior of the dynamic shear and bulk moduli against the interfacial tension, component compressibility, viscosity, and inclusion volume fraction is discussed. Victor G. Oshmyan deceased.     

Second order explicitly correlated R12 theory revisited: a second quantization framework for treatment of the operators' partitionings

Second order R12 theory is presented and derived alternatively using the second quantized hole-particle formalism. We have shown that in order to ensure the strong orthogonality between the R12 and the conventional part of the wave function, the explicit use of projection operators can be easily avoided by an appropriate partitioning of the involved operators to parts which are fully describable within the computational orbital basis and complementary parts that involve imaginary orbitals from the complete orbital basis. Various Hamiltonian splittings are discussed and computationally investigated for a set of nine molecules and their atomization energies. If no generalized Brillouin condition is assumed, with all relevant partitionings the one-particle contribution arising in the explicitly correlated part of the first order wave function has to be considered and has a significant role when smaller atomic orbital basis sets are used. The most appropriate Hamiltonian splitting results if one follows the conventional perturbation theory for a general non-Hartree-Fock reference. Then, no couplings between the R12 part and the conventional part arise within the first order wave function. The computationally most favorable splitting when the whole complementary part of the Hamiltonian is treated as a perturbation fails badly. These conclusions also apply to MP2-F12 approaches with different correlation factors.     

Modern Trends in the In Vitro Production and Use of Callus,Suspension Cells and Root Cultures of Medicinal Plants

This paper studies modern methods of producing and using callus, suspension cells and root cultures of medicinal plants in vitro. A new solution for natural product production is the use of an alternative source of renewable, environmentally friendly raw materials: callus, suspension and root cultures of higher plants in vitro. The possibility of using hairy root cultures as producers of various biologically active substances is studied. It is proven that the application of the genetic engineering achievements that combine in vitro tissue culture and molecular biology methods was groundbreaking in terms of the intensification of the extraction process of compounds significant for the medical industry. It is established that of all the callus processing methods, suspension and root cultures in vitro, the Agrobacterium method is the most widely used in practice. The use of agrobacteria has advantages over the biolistic method since it increases the proportion of stable transformation events, can deliver large DNA segments and does not require special ballistic devices. As a result of the research, the most effective strains of agrobacteria are identified.     

Visions of the electrochemical future,past and present: Plus ca change?

Journal of Solid State Electrochemistry -     

Group IV complexes of a tetradentate amine mono(phenolate) ligand: a second side-arm donor stabilizes cationic species

An amine mono(phenolate) ligand bearing two side-arm donors led to octahedral trialkoxo and trialkyl group IV metal complexes, in which one of the donors was unbound, and to exceptionally stable cationic complexes in which the two side-arm donors were tightly bound.     

Geometrical and electronic structures of dinuclear complex ions {(mu-bpym)[Cu(EAr3)2]2}2+ with intramolecular "organic sandwich" formation (E = P or As; Ar = Aryl; bpym = 2,2'-bipyrimidine)

The compound {(mu-bpym)[Cu(AsPh3)2]2}(BF4)2 (1) has been prepared and studied in comparison with the triphenylphosphine analogue 2. Qualitatively, the structure of 1 with characteristically distorted copper(I) coordination caused by Ph/bpym/Ph sandwich interactions is similar to that of 2 and is approximately reproduced by DFT calculations for the model complex ions {(mu-bpym)[Cu(EMe2Ph)2]2}2+, E = P or As. In contrast, the dinuclear {(mu-bpym)[Cu(P(3-Me-C6H4)3)2]2}(BF4)2 (3) displays a distinctly less distorted metal coordination geometry due to the steric requirements of the methyl groups in the meta-tolyl substituents. The electrochemical reduction of 1 is less reversible than for the phosphine analogues; the one-electron-reduced form 1*- exhibits a broad, unresolved EPR signal at g = 2.0023. Resonance Raman spectroscopy of 1 shows the typical vibrations of the bpym ligand in agreement with the MLCT assignment of the long-wavelength transitions below 500 nm. All three dinuclear complexes exhibit luminescence at room temperature in the solid and in solution.     

A novel approach for coincidence ion mass spectrometry

A novel approach is proposed for extracting a maximum of information from secondary ions ejected when surfaces are bombarded with keV mono or polyatomic ions. It is known that the event-by-event bombardment-detection mode allows identification of spatiotemporal relationships among individual secondary ions which in turn reveal surface composition within nanometric dimensions. We have devised a procedure for identifying spatiotemporal relationships among individual secondary ions without the requirement of pulsed sample interrogation (one single projectile at a time). The consequence of "mass separated time-of-flight mass spectrometry" is a much improved measurement duty cycle.     

A dynamical model of water recycling in a mine-processing enterprise

We consider a mine-processing enterprise, which runs a number of production plants. Each plant uses a considerable amount of water which is polluted during the production process. The aim is to determine the optimal amounts of water to be taken from a river or to be pumped back from a waste water reservoir. The problem is decomposed in two tasks. Task 1 is formulated as a time-discrete optimal control model and determines the amounts of water pumped in each period. The solution method used is dynamic programming. While Task 1 has an ecological objective (minimize environmental damage), in Task 2 the aim is to determine, by which pump configurations the desired quantities of water are most efficiently brought to reservoir (with least cost). Because of the special structure of this linear programming problem it can be solved simply by sorting with respect to unit costs.