Application of matrix-assisted laser desorption/ionization in the studies of phosphotungstic acid.

Rationale: Phosphorotungstic acid (PTA) has many applications, especially in the field of catalysis, due to its structural properties. However, the structure of PTA is studied mainly using theoretical methods. Matrix-assisted laser desorption/ionization (MALDI) has the potential to be an effective method for the experimental study of heteropolyacids.

Gas-phase thermochemistry of polycyclic aromatic hydrocarbons: an approach integrating the quantum chemistry composite scheme and reaction generator.

We introduce a protocol aimed at predicting the accurate gas-phase enthalpies of formation of polycyclic aromatic hydrocarbons (PAHs). Automatic generation of a dataset of equilibrated chemical reactions preserving the number of carbon atoms in each hybridization state on each side of equations is at the core of our scheme. The performed tests suggest the recommended enthalpy of formation to be derived a two-step scheme.

Gas-Phase Thermochemistry of MX and MX (M = Sc, Y; X = F, Cl, Br, I) from a Composite Reaction-Based Approach: Homolytic versus Heterolytic Cleavage.

A domain-based local-pair natural-orbital coupled-cluster approach with single, double, and improved linear-scaling perturbative triple correction via an iterative algorithm, DLPNO-CCSD(), was applied within the framework of the Feller-Peterson-Dixon approach to derive gas-phase heats of formation of scandium and yttrium trihalides and their dimers via a set of homolytic and heterolytic dissociation reactions. All predicted heats of formation moderately depend on the reaction type with the most and least negative values obtained for homolytic and heterolytic dissociation, respectively. The basis set size dependence, as well as the influence of static correlation effects not covered by the standard (DLPNO-)CCSD() approach, suggests that exploitation of the heterolytic dissociation reactions with the formation of M and X ions leads to the most robust heats of formation.

Gas Phase Silver Thermochemistry from First Principles.

Domain-based local pair natural orbital coupled cluster approach with single, double, and perturbative triple excitations, DLPNO-CCSD(T), has been applied within a framework of a reduced version of the reaction-based Feller-Peterson-Dixon (FPD) scheme to predict gas phase heats of formation and absolute entropies of silver inorganic and organometallic compounds. First, we evaluated all existing experimental data currently limited by thermodynamic functions of 10 silver substances (AgH, AgF, AgBr, AgI, Ag, AgS, AgSe, AgTe, AgCN, AgPO). The mean average deviation between computed and experimental heats of formation was found to be 1.

The crystal-forming strains of Bacillus laterosporus.

Bacillus laterosporus is a spore-forming bacterium characterized by its ability to produce a canoe-shaped lamellar parasporal inclusion, adjacent to the spore. In some B. laterosporus strains crystalline inclusions of various shapes and sizes, which are released separately from spores during the lysis of the sporangium, were also produced.

[Structural and molecular-biological characteristics of a new transducing phage from Bacillus thuringiensis Tt 91].

A new bacteriophage Tt91 of larger size and broad lytical spectrum has been isolated from soil to widen the possibility to study new Bacillus thuringiensis strains. The Tt91 bacteriophage was shown to perform the intravariant transduction and, thus, can be used for genetic mapping. The ultrastructural analysis made it possible to refer bacteriophage Tt91 to morphotype A1 and showed similarity of Tt91 morphological structure to the one of CP-group bacteriophages.

[Genetic properties of the nonflagellar Bacillus thuringiensis mutant].

The nonflagellar mutant has been selected in Bacillus thuringiensis strain 33-69 var. galleriae. The absence of flagella in the mutant cells is confirmed by electron microscopy, by the specific "trench transit" test.

[Characteristics of Bacillus thuringiensis phages with circular permutation in the DNA molecule].

Bacteriophages Tm2 and Tg27 of different origins but identical in biological properties have been compared. Physicochemical characteristics of bacteriophages have revealed the existence of end repeats and circular permutation of phage DNA. Phages Tm2 and Tg27 share the same dimensions of incapsulated DNA, differing in the sizes of phage genome and end repeats.

Pseudomonas bacteriophage phi KZ contains an inner body in its capsid.

Electron microscopical examination of the new virulent bacteriophage phi KZ, specific for Pseudomonas aeruginosa, has revealed an unusual structure in its capsid. In the center of the phage head is a cylinder of low electron density ("inner body"), surrounded by fibrous material which is packed around the inner body in a spoollike manner. The inner body itself has a springlike appearance.

[Electron microscope study of the intracellular development of the Pseudomonas aeruginosa bacteriophage phi KZ].

The study of the ultrathin sections of cells infected with virulent phage phi KZ has confirmed the presence of a specific cylindrical formation, an inner body, in the head of this phage and revealed the spiral structure of this inner body. The formation of DNA condensates whose structure resembles a spring wound around the core (the inner body) has been shown to occur in the cells in the process of the ultracellular development of phage phi KZ. This development leads to characteristic changes in the cellular structure, and in particular in the cell walls and the nucleoid.

[Lysogeny in Bacillus thuringiensis].

Different strains of several Bacillus thuringiensis serotypes were analyzed for lysogeny. All of the studied cultures released phages. Phages with an isometric capsid and a noncontractible tail were detected in preparations of the majority of the cultures.

[Electron microscopic study of the interaction between phages and Bacillus thuringiensis cells].

The interaction of phages belonging to different morphological groups with the cells of Bacillus thuringiensis var. galleriae R and S variants was studied. No adsorption of phages Tg11 and Tg18 on the cells of R variant was found upon infection in a liquid medium.

[Bacteriocin-like factor in Bacillus thuringiensis].

The paper describes Bacillus thuringiensis var. galleriae strains possessing a bacteriocin-like factor (factor K) which inhibits the cultures of a number of serotypes of Bac. thuringiensis.

[Isolation and general characteristics of a group of Pseudomonas aeruginosa temperate phages].

Eighteen temperate phages were isolated from 38 natural strains of Pseudomonas aeruginosa. The phages belong to five heteroimmune groups according to the ability of lysogenic variants of the strains PAO1 and PAT2 to exclude the growth of the superinfecting phage. Phages of the II and V immunity groups are serologically similar; the remaining phages are not inactivated by antisera against phages B26 (II group) and K1338 (V group).

[Stucture of PhiKZ bacteriophage particles].

The structure of the particle of a new bacteriophage Pseudomonas phiKZ was studied. The particle of phiKZ bacteriophage was shown to have some features distinguishing this phage from all those known heretofore: a large size of the head and DNA and the presence in the head of a special structural formation named the central body. The central has a cylindrical shape and may be isolated from the head of the phage by repeated freezing-thawing the phage preparation.

[Electron microscopic study of Bacillus subtilis mutants differing in the serine proteinase activity and spectrum].

Vegetative cells and spores of the colonial morphological mutants of Bacillus subtilis A-50 were studied by electron microscopy. The ultrastructure of vegetative cells from both asporogenic colonial-morphological mutants and those which were capable of forming spores in the presence of high concentrations of nitrogen and carbon sources with a decreased activity and a modified spectrum of serine proteases differed from the parent strain by the presence of a microcapsule, the uneven thickness of a cell wall, and the absence of a distinct periplasmic space. Crystalline inclusions of a regular shape were detected in the sporeforming mutant in those cells which were devoid of spores.

[Electron microscopic study of the cells of variants of Bacillus thuringiensis var. galleriae forming colonies with altered morphology].

Colonial-morphological variants of Bacillus thuringiensis var. Galleriae were studied by electron microscopy. The S variant was found to be asporogenous, whereas the R variant produced mature spores.

[Characteristics of phages of spore-forming bacteria isolated from the soil].

Phages lyzing spore forming bacteria were isolated from soil, and their biological properties and fine structure were studied. The spectrum of lytic activity was determined as well as parameters of the intracellular phage growth. The burst size of the phage varies from 8 to 725 particles per infected cell, the latent period lasts 25-100 min for various phages.

[Preliminary electron microscopic and x-ray study of the crystalline protein of diphtheria toxin].

The authors present the results of the electron microscopic and roentgenological study of the crystalline protein of diphtheria toxin. On the basis of direct measurements of the crystal image and diffraction pictures it was possible to calculate the interplane distances of the placement of molecules in the crystal. Examination in polarization microscope showed that the crystals were optically uniaxial with a direct extinction and a positive character of elongation.