Results 1 - 10 of 1924
Results 1 - 10 of 1924. Search took: 0.024 seconds
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[en] The present work investigates the galvanostatic obtaining of alloy coatings Zn-Fe-P from sulfate electrolytes. Cyclic voltaamogramms show that the co-deposition of zinc with phosphorus is possible only in the presence of iron ions in the electrolytic bath. The including of P in the coating occurs at iron amounts higher than 9 wt% - higher iron concentration leads to higher phosphorus amounts. Fine crystal surface structure with spherical agglomerates characteristic for the amorphous layers is obtained even of 0,5 - 2 wt% phosphorus. Entirely amorphous and uniform coatings can be practically obtained only at very thin films. Potentiodynamic curves in IN Na2SO4 show that Zn-Fe-P alloy containing up to 2 wt% P and 20 wt% Fe demonstrate better corrosion characteristics compared to Zn-Fe coatings. Key words: electrodeposition, Zn-Fe-P alloys, cyclic voltammetry
PurposeTo evaluate the effect of air, CO2 and contrast medium-air on the dwell time (DT) stability of sodium tetradecyl sulfate (STS) foam.
Materials and MethodsThree types of foam sclerosants (air-foam, CO2-foam, contrast-air-foam) were injected eight times into an inclined straight plastic tube (internal diameters 4 mm and 10 mm) filled with a blood substitute. Injections were captured by CCD camera, and images were transferred for digital analysis and calculation of DT.
ResultsContrast-air-foam and air-foam in a 4-mm tube showed 5.6-/3.3-fold greater DT compared to CO2-foam, respectively (P#Thin Space#= 0.001). Contrast-air-foam in a 10-mm tube showed 2.1-fold greater DT compared to CO2-foam (P#Thin Space#= 0.0167).
ConclusionA mixture of air and iodinated contrast improves the stability of STS foam compared to mixtures using only air or CO2. Further, animal and clinical studies are needed to validate this in vitro result.
[en] Lyotrophic phase transitions were investigated in liquid crystalline systems of sodium alkyl sulfate-water. The positron annihilation parameters indicated the presence of a nematic phase in sodium dodecyl sulfate water system in absence of additives. The effect of the hydrocarbon chain-length and unsaturation of the surfactant on the nematic phase formation were also studied. Liquid crystals of sodium 10-undecenoate were polymerized by ultraviolet irradiation. Polymerization is seen to cause a gradual change from the hexagonal to the lamellae phase. (author)
[en] The dehydration process of sodium sulphatozirconates (SSZ) has been studied by the method of thermal analysis. Dehydration of SSZ with a mole ratio of SO4 : Zr (<=) 2.0 has been studied. Temperatures and the character of dehydration end effects differ sharply for neutral and acid salts. A lower temperature of dehydration of neutral salts confirms an assumption that saturation of inner sphere of zirconium in these salts is higher than in acid salts. In the series of acid salts from disulphatozirconates to 1.75 SSZ the temperature of dehydration onset rises and can be characteristic of the phase. A method is recommended of vacuum drying sodium sulphatozirconates at a total residual pressure of p=100 mm Hg, partial pressure of Psub(H2O) < 45 mm Hg, and a final temperature of the material approximately 100 deg C. The process of SSZ production can be run by evaporating of the solutions in the range of 100-200 deg C without decomposition of the salt; but removal of crystallohydrate water can lead to regrinding of the product
[en] The passivity of oxide films formed on nickel in acid and neutral Na2SO4 solution, both with and without additions of chloride ions, at 25 .deg. C, has been investigated. It is found that the role of Cl- in pitting of nickel is related to its ability to destroy the oxide films at local weak points, mainly at the grain boundaries, and the overall resistance of oxide films formed in the presence of Cl- decreases due to the more defective oxide formation by Cl-. In addition, the sulfide inclusion is observed to be the pit nucleation site, indicating that the localized attack starts in the sulfide inclusion, which is less noble than the surrounding oxide film, and then spreads to the active metal below the sulfide inclusion
[en] Hot corrosion behavior of pure Ni wire specimen dipped in 1200 .deg. K pure Na2SO4 melt under Ar atmosphere has been studied by means of electrochemical methods. Ag(s)/Ag2SO4(1) half cell electrode contained in a mullite membrane was used as a reference electrode. Potentiodynamic polarization curves for the specimens demonstrated a definite active-passive transition but soon after the transition they showed rather a transpassive region than a passive region with increasing potential indicating the passive film is non-protective in the melt. Ni wire specimen under freely corroding condition spontaneously passivated, which suggests Na2SO4 itself functions as an oxidizing agent. EPMA revealed that nickel sulfide was formed beneath surface oxide scale and in grain boundaries in freely corroding conditions as well as during potentiostatic anodic polarization at potentials in the passive and transpassive region. Discussion on the reduction mechanisms of sulfate ion is given in the text. It was interesting that Ni was cathodically protected at potentials slightly negative to the open circuit potential in the Na2SO4 melt
[en] Sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) of wheat (Triticum aestivum L) flour have revealed 23 polypeptides of molecular weights between 170 and 11.57 KDa, High molecular weight glutenin subunits (LMW-GS) were distinguished. Densitometric analysis of the gel showed the effect of radiation on polypeptide constitution at radiation energy up to 7.5 kGy. Irradiation of wheat flour with 2.5 kGy have resulted in a slight increase in the molecular weight of wheat flour protein subunits. The increase of irradiation dose to 5.0 kGy has also induced an additional increase of molecular weight of protein subunits. The continuity in application of more radiation energy to a level of 7.5 kGy have resulted in the prevalence of degradation processes of all protein subunits more than the aggregation
[en] Bacterial biofilms present a societal challenge, as they occur in the majority of infections but are highly resistant to both immune mechanisms and traditional antibiotics. In the pursuit of better understanding biofilm biology for developing new treatments, there is a need for streamlined, controlled platforms for biofilm growth and evaluation. We leverage advantages of microfluidics to develop a system in which biofilms are formed and sectioned, allowing parallel assays on multiple sections of one biofilm. A microfluidic testbed with multiple depth profiles was developed to accommodate biofilm growth and sectioning by hydraulically actuated valves. In realization of the platform, a novel fabrication technique was developed for creating multi-depth microfluidic molds using sequentially patterned photoresist separated and passivated by conformal coatings using atomic layer deposition. Biofilm thickness variation within three separately tested devices was less than 13% of the average thickness in each device, while variation between devices was 23% of the average thickness. In a demonstration of parallel experiments performed on one biofilm within one device, integrated valves were used to trisect the uniform biofilms with one section maintained as a control, and two sections exposed to different concentrations of sodium dodecyl sulfate. The technology presented here for multi-depth microchannel fabrication can be used to create a host of microfluidic devices with diverse architectures. While this work focuses on one application of such a device in biofilm sectioning for parallel experimentation, the tailored architectures enabled by the fabrication technology can be used to create devices that provide new biological information. (paper)
[en] The accelerated oxidation of Na2SO4 coated nickel has been studied at 1014 .deg. C, 932 .deg. C and 854 .deg. C in dynamic air. It has been observed that a linear oxidation law is obeyed during an initial accelerated oxidation stage, however, after a long time oxidation, the oxidation rates were diminished and parabolic oxidation behavior is shown because of the formation of inner protective oxide layer. The oxide layers which were formed during an accelerated oxidation were porous and lamellate structures and sulfide phase was observed at inner sides of the porous oxide layers and grain boundaries of nickel matrix. Based upon the above results, the mechanism of the accelerated oxidation of nickel by Na2SO4 is considered as follows. (a) Fracture or dissolution of initially formed nickel oxide film occurs. (b) Nickel is sulfidized reacting with Na2SO4 or SO2 and nickel dissolves into the fused sulfide phase. (c) Dissolved nickel ions react with oxygen in the sulfide phase or just outer sides of the sulfide phase and porous oxide layers are formed. It is also considered that inner protective oxides are formed when the amount of sulfide phase is below a critical amount, since sulfides are consumed by oxidation or dissolving into porous oxide layers