Monitoring of dynamic processes by rectangular hybrid automata

In this paper we develop a method of monitoring dynamic processes based on rectangular hybrid automats. This method takes into account the behavior of the system and the evolution of its parameters. A failure during the execution of the process can lead to a dysfunctional state in the system.The monitoring system, we propose, makes it possible to detect this state of dysfunction as soon as possible thanks to the reachability analysis.     

Separation of quaternary ammonium diastereomeric oligomers by capillary electrophoresis

The separation of novel diastereomeric trimers (3M) and pentamers (5M), derived from quaternary ammonium salts, was studied in conventional, uncoated and coated capillaries using capillary zone electrophoresis (CZE) with a variety of buffers and additives. Resolution of 5M diastereomers was best achieved using gamma-cyclodextrin (gamma-CD) as a chiral selector, while no diastereomeric resolution was realized for the 3M material.     

Chemistry of vinylidene complexes. XVI. Crystal and molecular structure of the novel tetranuclear μ2-μ3-bis-vinylidene complex (η-dppe)PdMn(μ3-CCHPh)PdMn(μ-CCHPh)(CO)4Cp2

The crystal and molecular structure of the novel tetranuclear complex (η²-dppe)PdMn(μ₃-CCHPh)PdMn(μ-CCHPh)(CO)₄Cp₂ (5) has been investigated. The metal core of 5 is a bent chain Pd(2)-Mn(2)-Pd(1)-Mn(1). The bond distances and angles are Mn(1)-Pd(1) 2.6025(6), Pd(1)-Mn(2) 2.8913(5), Mn(2)-Pd(2) 2.6463(4) Å, Mn(1)-Pd(1)-Mn(2) 140.2(2)°, Pd(1)-Mn(2)-Pd(2) 69.6(1)°. Complex contains two bridging vinylidene ligands coordinated to metal atoms in different ways. The CC bond lengths are 1.347(4) and 1.372(4) Å in the μ₂(η¹,η¹)-CCHPh and μ₃(η¹,η¹,η²)-CCHPh ligands, respectively. The η²-dppe ligand is coordinated to the Pd(2) atom to form the chelate cycle. Each of Mn(1) and Mn(2) atoms is bonded with the η⁵-C₅H₅ ring and two CO groups.     

Percolation transition in supercritical water: a Monte Carlo simulation study

Computer simulations of water have been performed on the canonical ensemble at 15 different molecular number densities, ranging from 0.006 to 0.018 A-3, along the supercritical isotherm of 700 K, in order to characterize the percolation transition in the system. It is found that the percolation transition occurs at a somewhat higher density than what is corresponding to the supercritical extension of the boiling line. We have shown that the fractal dimension of the largest cluster and the probability of finding a spanning cluster are the most appropriate properties for the location of the true percolation threshold. Thus, percolation transition occurs when the fractal dimension of the largest cluster reaches 2.53, and the probability of finding a cluster that spans the system in at least one dimension and in all the three dimensions reaches 0.97 and 0.65, respectively. On the other hand, the percolation threshold cannot be accurately located through the cluster size distribution, as it is distorted by appearance of clusters crossing the finite simulated system even far below the percolation threshold. The structure of the largest water cluster is dominated by a linear, chainlike arrangement, which does not change noticeably until the largest cluster becomes infinite.     

Self-Similarity of solvent-accessible surfaces of biological and synthetical macromolecules

The quantification of surface roughness of globular proteins and synthetical macromolecules in the globular state is discussed using the concept of fractality. The Hausdorff dimension as a measure for local and global fractality of surfaces is applied. To calculate the Hausdorff dimension of any surface at a high level of accuracy, a new algorithm is presented that is based on a triangulated solvent-accessible molecular surface. It can be demonstrated that protein surfaces (as calculated on the basis of experimentally determined structures) as well as surfaces of globular polyethylene (PE) conformers (calculated on the basis of structural information basing on extensive Monte Carlo and molecular dynamics simulations) in fact show self-similarity within a reasonable yardstick range, at least in a global statistical sense. The same is true for parts of a protein surface provided that these regions are not too small. The concept of self-similarity breaks down when individual surface points are considered. The results obtained for the fractal dimension of PE surfaces (average fractal dimension D = 2.23) lead to the conclusion that protein surfaces probably do not exhibit a unique and specific degree of geometrical complexity (or surface roughness) characterized by a fractal dimension of approximately D = 2.2 as was argued in the past. It is clear that the concept of self-similarity is helpful for the classification of surface roughness of large molecules, but it seems questionable whether this concept is useful for the identification of active sites or other questions related to the field of molecular recognition. © John Wiley & Sons, Inc.     

Maleic Anhydride Crosslinked Alginate-Chitosan Blend Membranes for Pervaporation of Ethylene Glycol-Water Mixtures

Calcium alginate-chitosan (CA/CS) blended membranes were prepared and crosslinked with maleic anhydride (MA) for the pervaporation (PV) separation of ethylene glycol (EG)/water mixtures at 30°C. The structure and properties of blend membranes were studied with the aid of FTIR, XRD, TGA, and SEM. The effect of experimental parameters such as feed composition, membrane thickness, and permeate pressure on separation performance of the MA crosslinked membranes were determined in terms of flux, selectivity, and pervaporation separation index. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the blend membranes in pure, as well as in binary mixtures. The experimental results suggested that the crosslinked membrane (M-CA/CS) exhibited a good selectivity of 302 at a normalized flux of 0.38 kg.m^{? 2}.h^{? 1}.10 μ m at 30°C for 96.88 wt% EG aqueous solution.     

镍钼杂多酸制备NiMo/γ-Al2O3催化剂及硼、钴或镍改性氧化铝的影响（英文）

A hydrotreating NiMo/γ-Al2O3 catalyst(12 wt% Mo and 1.1 wt% Ni) was prepared by impregnation of the support with the Anderson-type heteropolyoxomolybdate(NH4)4Ni(OH)6Mo6O18.Before impregnation of the support,it was modified with an aqueous solution of H3BO3,Co(NO3)2,or Ni(NO3)2.The catalysts were investigated using N2 adsorption,O2 chemisorption,X-ray diffraction,UV-Vis spectroscopy,Fourier transform infrared spectroscopy,temperature-programmed reduction,temperature-programmed desorption,and X-ray photoelectron spectroscopy.The addition of Co,Ni,or B influenced the Al2O3 phase composition and gave increased catalytic activity for 1-benzothiophene hydrodesulfurization(HDS).X-ray photoelectron spectroscopy confirmed that the prior loading of Ni,Co or B increased the degree of sulfidation of the NiMo/γ-Al2O3 catalysts.The highest HDS activity was observed with the NiMo/γ-Al2O3 catalyst with prior loaded Ni.     

Characterization of silica-supported molybdenum catalysts by ESR, XPS and thiophene hydrodesulfurization

Two Mo/SiO₂ samples have been prepared by impregnation of silica gel with aqueous solution of molybdophosphoric heteropoly acid or ammonium heptamolybdate. The catalysts were studied by ESR and IR spectroscopy, X-ray diffraction, and XPS. Their activity was measured in the reaction of thiophene hydrodesulfurization. The silica-supported P–Mo heteropoly acid, with a preserved Keggin structure of the heteropoly anion and sulfided by H₂S, exhibited two times higher steady conversion in comparison with ammonium heptamolybdate supported on silica at pH=11 and calcined and sulfided at 500°C.     

Compression of Polymer Brushes Under a Lateral Force

Summary: The influence of a lateral force (or lateral shear) acting on chains in a polymer brush is investigated theoretically. Brushes consisting of chains with temperature dependent anisotropic interactions between monomers (main‐chain mesogenic groups) are considered. It is shown that a lateral force applied to polymer brush induces its compression. In contrast to a conventional brush, the compression of brush, capable of forming a liquid crystalline (LC) state, can be caused by comparatively small shear forces. Moreover, such shear forces can induce a phase transition of a brush into the tilted LC state with a several‐fold decrease in brush thickness. These results allow us to predict a possibility to observe a decrease in brush thickness in a real experiment with reasonably values of shear rate.

Model of a chain in a polymer brush under an influence of lateral force p.     

On solvability of stochastic differential inclusions with current velocities

An existence of solution theorem is obtained for stochastic differential inclusions given in terms of the so-called current velocities (direct analogues of ordinary velocity of deterministic systems) and quadratic mean derivatives (giving information on the diffusion coefficient) on the flat n-dimensional torus. The current velocity part is single-valued while the quadratic part is set-valued and takes values in symmetric (2,?0) tensors with unit determinant.