Baculovirus surface display of Theileria parva p67 antigen preserves the conformation of sporozoite-neutralizing epitopes

Theileria parva is an intracellular protozoan parasite thatcauses East Coast fever, a severe lymphoproliferative diseasein cattle. Previous attempts to produce recombinant sporozoitesurface antigen (p67) in bacterial or insect cells for vaccinepurposes have not resulted in a correctly folded protein. Here,we report the expression of N- and C-terminal domains of p67fused to the baculovirus envelope glycoprotein GP64 by cloningthe appropriate p67 cDNA segments between the signal sequenceand the major portion of GP64. To further advance the generationof such recombinants, existing surface display techniques werecombined with bacmid technology. Chimeric proteins were presenton the surface of budded viruses as judged by immunogold labellingand were exposed on the surface of insect cells, as concludedfrom immunofluorescence studies of infected, non-fixed insectcells. In non-denaturing dot blot experiments, a strong reactionwas obtained between monoclonal TpM12 and baculovirus particlesdisplaying the p67N-GP64 chimeric protein. This antibody, raisedagainst native p67, also specifically recognized the surfaceof recombinant-infected cells. Apparently, a more native conformationwas achieved than when p67 was expressed in E.coli or in conventionalbaculovirus expression systems. The baculovirus surface expressionsystem, therefore, provides an improved way of expressing thisT.parva sporozoite surface protein.     

Compressor designing, manufacturing, and testing at Iskra NPO

Results of acceptance tests and gas-dynamic characteristics of a series of compressors for gas pumping units are reported. The work at the Iskra NPO on compressor making over the past decade and future plans are described.     

Surface plasmon resonance sensor using an optical fiber with an inverted graded-index profile

A new optical fiber sensor based on surface plasmon resonance is described. It uses an optical fiber with an inverted graded-index profile. A theoretical analysis of the optical propagation when a point light source was used and a computation of the optical power transmitted by the fiber were performed. Experiments were carried out to measure changes of the transmitted power caused by refractive-index variations of the surrounding dielectric medium. Both the simulation and experiments have shown that the sensor exhibits high sensitivity for changes of the surrounding medium in a refractive index range from 1.33 to 1.39.     

Electrochemical oxidation of carbon in a 62/38 mol % Li/K carbonate melt

The electrochemical gasification of coal to CO in a direct carbon fuel cell (DCFC) has thermodynamical advantages, including the conversion of heat into power at a reversible efficiency of 100%. Molten carbonate fuel cell (MCFC) technology may form the basis for constructing DCFC's. Here the electrochemical oxidation of carbon in a 62/38 mol % Li/K carbonate melt is studied using impedance spectroscopy (IS) and cyclic voltammetry (CV). A set of equilibria is introduced which fully describes the electrochemical equilibrium of the system. From IS it is shown that for temperatures lower than 700 °C, charge transfer is the slowest step, while at higher temperatures a second unidentified step also contributes significantly to the d.c. resistance of the electrode. The d.c. resistance is 100 to 220 cm² at 650 °C and 12 to 60 cm² at 750 °C, depending on the carbon surface roughness.     

Effect of volcanic pumice powder on the fresh properties of self-compacting concretes with and without silica fume

The current study presents an experimental study conducted on the effectiveness of volcanic pumice powder (VP) on the fresh properties of self-compacting concretes (SCCs) with and without silica fume (SF). In the first group, SCCs without SF were produced with 0, 5, 10, and 20 % replacement levels of VP. However, for the second group, SF incorporation was achieved by a constant SF replacement level of 8 %. All of the replacement levels assigned were substitution of cement with the supplementary cementing materials on the basis of weight of total binder. Therefore, totally eight different SCCs were produced. The investigated fresh characteristics of the concretes were slump flow diameter, T _500mm slump flow time, V-funnel flow time, and L-box height ratio. The compressive strength of concretes was also evaluated to indicate the mechanical performance. Moreover, a statistical study, namely general linear model analysis of variance, was performed in order to examine the significance of the critical parameters such as inclusion of SF and replacement level of VP on the properties of SCCs. The results have revealed that increasing the replacement level of VP generally resulted in the increase of fluidity of SCCs without loss of uniformity and with no segregation. Moreover, incorporation of SF provided significant increase in compressive strength while VP caused a systematic decrease.     

Poly-l -lactic acid modified by etching and grafting with gold nanoparticles

This work is focused on characterization of plasma treated and consequently etched and grafted biocompatible polymer poly(l-lactide acid) (PLLA). The interaction of biodegradable polymers with cold plasma is of a great importance in a tissue engineering and surface science. Cold plasma exposure, grafting with gold nanoparticles and etching processes were successfully applied to biopolymer substrate. A method for biopolymer nanostructuring as combination of cold plasma treatment and Au nanoparticle grafting for biocompatibility improvement is introduced. Surface roughness, morphology and surface chemistry was determined. The plasma modification leads to significant increase in surface roughness of PLLA and appearance of sharp spikes and ridges on the PLLA surface. Modification by grafting and etching leads to significant changes in PLLA surface morphology and chemistry. The surface ablation of PLLA has been proved to be significant. In etching of plasma-modified PLLA, methanol proves to be stronger etching agent than water. The grafting of PLLA with gold nanoparticles improved mouse embryonic fibroblasts (NIH 3T3) adhesion and proliferation significantly.     

On modelling molten carbonate fuel-cell cathodes by electrochemical potentials

We derive an electrochemical-potential model for the peroxide mechanism describing the electrochemistry of a molten carbonate fuel cell cathode. The advantages of this model include elegantly combining the chemical and electrical processes, making clear the connection to the underlying reaction stoichiometry, and requiring the fewest equations consistent with that stoichiometry. The relationship between electrochemical-potential and concentration models is also discussed, along with a two-dimensional computational study of the effects of variations in electrode geometry or coefficient parameters. In particular, it is shown that the mean current density associated with a small portion of electrode may be increased by as much as a factor of five by carefully redistributing the electrolyte, and that on this scale the current density is most sensitive to the electrolyte diffusivity.     

TiCN and metallic coatings for corrosion protection of separator plates in MCFCs

Stainless steel 304 substrates were coated with different materials in order to find a suitable coating material for corrosion protection of separator plates in molten-carbonate fuel cells (MCFCs). Five titanium carbonitride coatings differing in composition and morphology and a titanium monoxide coating were deposited with chemical vapour deposition techniques. Also double-layer coatings of TiN/Au and TiN/Ni were prepared. The coatings were tested on their corrosion protection of separator plates in four different environments: under MCFC-cathode or anode gas, at load or at open circuit conditions. The corrosion behaviour was characterized using cyclic voltammetry. Corrosion rates were determined with electrochemical methods and cross-section analyses of corrosion layers. Titanium nitride coatings showed the best corrosion protection. The titanium carbide and titanium monoxide coating showed respectively less and no protection. The thin gold and Ni-coatings were unstable. Under cathode gas, the most important corrosion protection is given by keeping the cell at load, and then a titanium nitride coating might provide lifetime protection. Under anode gas, corrosion is most severe at load conditions. A titanium nitride coating also gives corrosion protection, but not enough for lifetime protection.