A new form of iron-containing mineralizer for production of dinas parts

Conclusions Laboratory investigations have established that the rheological properties of a lime-iron slip with use of open hearth electric filter dust used in the production lot of dinas parts exceed those of a slip with pyrite cinders.The results of laboratory investigations and production of an experimental production lot of dinas parts of various types and sizes at Krasnogorovka Refractory Plant indicate the promise and desirability of introduction of production of dinas parts with use of open hearth electric filter dust as the iron-containaing mineralizer in place of pyrite cinders.S. N. Romanenko and L. M. Khvostishkova participated in the work.Translated from Ogneupory, No. 8, pp. 17–19, August, 1993.     

Li2.6V6O16±y, K’-bronze: Synthesis by the alkoxide process, conductivity, and electrochemical performance

The K’-bronze Li_2.6V₆O_16+-y was prepared from VO(OPrⁱ)₂, VO(OBuⁱ)₃, and LiOR (R = Et, Pr). As determined by x-ray diffraction and electron scanning microscopy, the bronze had a highly textured microstructure. The vanadium(IV) and vanadium(V) contents of the bronze were determined by cyclic voltammetry, and the electrical conductivity was measured in the temperature range 20–400°C. The alkoxide process was shown to ensure good reproducibility of the electrical properties of the material. The electrochemical behavior of the bronze was studied in a 1 M solution of LiClO₄ in a propylene carbonate (70 wt %) + dimethoxyethane (30 wt %) mixture in a galvanostatic cycling regime using Li metal counter and reference electrodes     

Low-temperature filtration of gases using multilayer cermet filters

The performance characteristics of highly efficient cermet filters with a multilayer membrane structure used for the treatment of nitrogen, argon, helium, methane, carbon monoxide and dioxide at temperatures up to 75 K are studied. It is shown that as the temperature decreases, their collection efficiency with respect to a finely dispersed aerosol decreases. At low Reynolds numbers, the variation of the gas-flow pressure drop through the filters is determined by the gas viscosity. The multilayer nickel-based membrane structure is stable to substantial temperature gradients and can be regenerated by blowing and heating. It is found that the filter collection efficiency for liquid gases is determined by the pore size of the fine-pore selective layer of the filters according to the sieving mechanism of collecting dispersed particles.     

Replicon-helper systems from attenuated Venezuelan equine encephalitis virus: expression of heterologous genes in vitro and immunization against heterologous pathogens in vivo

A replicon vaccine vector system was developed from an attenuated strain of Venezuelan equine encephalitis virus (VEE). The replicon RNA consists of the cis-acting 5' and 3' ends of the VEE genome, the complete nonstructural protein gene region, and the subgenomic 26S promoter. The genes encoding the VEE structural proteins were replaced with the influenza virus hemagglutinin (HA) or the Lassa virus nucleocapsid (N) gene, and upon transfection into eukaryotic cells by electroporation, these replicon RNAs directed the efficient, high-level synthesis of the HA or N proteins. For packaging of replicon RNAs into VEE replicon particles (VRP), the VEE capsid and glycoproteins were supplied in trans by expression from helper RNA(s) coelectroporated with the replicon. A number of different helper constructs, expressing the VEE structural proteins from a single or two separate helper RNAs, were derived from attenuated VEE strains Regeneration of infectious virus was not detected when replicons were packaged using a bipartite helper system encoding the VEE capsid protein and glycoproteins on two separate RNAs. Subcutaneous immunization of BALB/c mice with VRP expressing the influenza HA or Lassa virus N gene (HA-VRP or N-VRP, respectively) induced antibody responses to the expressed protein. After two inoculations of HA-VRP, complete protection against intranasal challenge with influenza was observed. Furthermore, sequential immunization of mice with two inoculations of N-VRP prior to two inoculations of HA-VRP induced an immune response to both HA and N equivalent to immunization with either VRP construct alone. Protection against influenza challenge was unaffected by previous N-VRP immunization. Therefore, the VEE replicon system was characterized by high-level expression of heterologous genes in cultured cells, little or no regeneration of plaque-forming virus particles, the capability for sequential immunization to multiple pathogens in the same host, and induction of protective immunity against a mucosal pathogen.     

Flow Resistance of High-Velocity Multilayer Cermet Gas Filters

The aerodynamic resistance and aerosol-catching efficiency of fine, high-efficiency, and ultrahigh-efficiency multilayer cermet filters were measured at a gas velocity of 1–200 cm/s, 300°C, and gas pressures up to 50 atm. At small Reynolds numbers, the flow resistance of flat and cylindrical filter elements depends linearly on the gas velocity and is almost independent of the gas pressure. The effect of temperature on the flow resistance is explained by the temperature dependence of gas viscosity. The collection efficiency for particles larger than 0.2 m in diameter grows with increasing particle size and gas velocity.     

Analysis of RNA phage fr coat protein assembly by insertion, deletion and substitution mutagenesis

A structure-function analysis of the icosahedral RNA bacteriophagefr coat protein (CP) assembly was undertaken using linker-insertion,deletion and substitution mutagenesis. Mutations were specificallyintroduced into either pre-existing or artificially createdrestriction enzyme sites within fr CP gene expressed in Escherichiacoli from a recombinant plasmid. This directs synthesis of wildtype protein that undergoes self-assembly and forms capsid-likeparticles indistinguishable morphologically and immunologicallyfrom native phage particles. A series of fr CP variants containingsequence alterations in the regions which are (i) exposed onthe external surface of capsid or (ii) located on the contactingareas between CP subunits were obtained and their assembly propertiesinvestigated. The majority of mutants demonstrated reductionof assembly ability and formed either CP dimers (mutations atresidues 2, 10, 63 or 129) or both dimer and capsid structures(residue 2 or 69). The exceptions were variants demonstratingnormal assembly and containing insertions at residues 2, 50or 129 of thefr CP. A third type of assembled structure wasformed by a variant with a single amino acid substitution I104T.The aA-helix region (residues 97-111) is particularly sensitiveto mutation and any alteration in this region decreases accumulationof mutant protein in E.coli. The relative contributions of particularfr CP domains in maintenance of capsid structural integrityas well as the possible capsid assembly mechanism are discussed.