Experimental Study of Central and Minimum Elastohydrodynamic Film Thickness by Colorimetric Interferometry Technique

Recently developed colorimetric interferometry technique was used for the study of both minimum and central film thicknesses for a wide range of operating parameters. Over 300 film thickness maps were obtained for the combination of four values of the materials parameter G, five values of the load parameter W and many values of the speed parameter U. The use of a spacer layer extended the range of film thickness measurement down to 5 nm. An excellent agreement was found between experimental values and data obtained from numerical solution presented by Venner and ten Napel, especially for thin lubrication films. An increase in a speed exponent with increasing material parameter G was observed for both central and minimum film thicknesses. The minimum film thickness and, thereby, the ratio between central and minimum film thickness was confirmed to be of a stronger dependence on material and load dimensionless parameters than Hamrock and Dowson equations predict.     

Lead and/or Lead Oxide Nanoparticle Generation for Inhalation Experiments

A method of the continual generation of lead or lead oxide nanoparticles for potential subsequent inhalation experiments with laboratory animals was investigated. We examined the thermal decomposition and oxidation of lead bis(2,2,6,6-tetramethyl-3,5-heptanedionate) in an externally heated tube reactor as well as the evaporation and condensation of metallic lead. The particle production dependence on experimental conditions was investigated using a scanning mobility particle sizer (SMPS), and the particle characteristics were studied using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic absorption spectroscopy (AAS), elemental and organic carbon analysis (EC/OC), X-ray photoelectron spectrometry (XPS), and X-ray diffraction (XRD) methods. The evaporation/condensation was evaluated as being the most suitable for inhalation experiments due to its simplicity, high production rate, and the well-defined composition of the nanoparticles.

Copyright 2015 American Association for Aerosol Research     

Ferrate(VI) oxidation of weak-acid dissociable cyanides

Cyanide is commonly found in electroplating, mining, coal gasification, and petroleum refining effluents, which require treatment before being discharged. Cyanide in effluents exists either as free cyanide or as a metal complex. The kinetics of the oxidation of weak-acid dissociable cyanides by an environmentally friendly oxidant, ferrate(VI) (Fe(VI)O4(2-), Fe(VI)), were studied as a function of pH (9.1-10.5) and temperature (15-45 degrees C) using a stopped-flow technique. The weak-acid dissociable cyanides were Cd(CN)4(2-) and Ni(CN)4(2-), and the rate-laws for the oxidation may be -d[Fe(VI)]/dt = k[Fe(VI)][M(CN)4(2-)]n where n = 0.5 and 1 for Cd(CN)4(2-) and Ni(CN)4(2-), respectively. The rates decreased with increasing pH and were mostly related to a decrease in concentration of the reactive protonated Fe(VI) species, HFeO4(-). The stoichiometries with Fe(VI) were determined to be: 4HFeO4(-) + M(CN)4(2-) + 6H2O --> 4Fe(OH)3 + M(2+) + 4NCO(-) + O2 + 4OH(-). Mechanisms are proposed that agree with the observed reaction rate-laws and stoichiometries of the oxidation of weak-acid dissociable cyanides by Fe(VI). Results indicate that Fe(VI) is effective in removing cyanide in coke oven plant effluent, where organics are also present.     

“合成”莫尔道玻陨石和天然莫尔道玻陨石的鉴别（英文）

近期,在宝石市场上出现了大量的合成莫尔道玻陨石。天然莫尔道玻陨石属于玻璃陨石的一种,由撞击地球表面的大陨石而形成。巨大的冲击能量至少可达到8km/s,引起陨石坑基岩(所谓的陨星坑)气化和熔化,并使得一部分物质进入到大气层上层(部分甚至进入到太空),最后在数百公里外落下。最初的莫尔道玻陨石坑位于德国Stuttgart附近的N9rdlingen,然而在捷克共和国South Bohemia的玻陨石散布地区有300~400公里,其南部摩拉维亚很少有发现。与天然莫尔道玻陨石相比,大部分合成莫尔道玻陨石有着异常的高光泽。天然莫尔道玻陨石通常有一个非常尖锐的表面(尤其是来自砂沉积物),与此相反,经过了水流搬运,莫尔道玻陨石表面变得光滑。合成莫尔道玻陨石边缘常常是光滑的,表面的光泽变得更强(通过酸洗)或者更弱。合成莫尔道玻陨石可以由多种方式雕刻,最好的方法之一就是像天然莫尔道玻陨石一样,在氢氟酸中选择性溶解。不同的是在天然莫尔道玻陨石中有焦石英的存在。焦石英常在天然莫尔道玻陨石表面较为突出(用放大镜容易看到),即使切磨好的宝石也可以看到。如果在有争议的情况下,Raman光谱仪或者UVVis光谱能被用以区分天然和合成莫尔道玻陨石。合成莫尔道玻陨石在长波紫外荧光(366nm)特征是具有象征意义的,相反,天然莫尔道玻陨石在此长波紫外下完全惰性。总体上,本文的测试结果显示合成和天然莫尔道玻陨石是完全不同的。     

Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

Technology of water-stabilized plasma torch was recently substantially updated through introduction of a so-called hybrid concept that combines benefits of water stabilization and gas stabilization principles. The high-enthalpy plasma provided by the WSP-H (“hybrid”) torch may be used for thermal spraying of powders as well as liquid feedstocks with high feed rates. In this study, results from three selected experiments with suspension plasma spraying with WSP-H technology are presented. Possibility of deposition of coatings with controlled microstructures was demonstrated for three different ceramics (YSZ—yttria-stabilized zirconia, YAG—yttrium aluminum garnet and Al₂O₃) introduced into ethanol-based suspensions. Shadowgraphy was used for optimization of suspension injection and visualization of the liquid fragmentation in the plasma jet. Coatings were deposited onto substrates attached to the rotating carousel with integrated temperature monitoring and air cooling, which provided an excellent reproducibility of the deposition process. Deposition of columnar-like YSZ and dense YAG and Al₂O₃ coatings was successfully achieved. Deposition efficiency reached more than 50%, as evaluated according to EN ISO 17 836 standard.     

Controlling Microstructure of Yttria-Stabilized Zirconia Prepared from Suspensions and Solutions by Plasma Spraying with High Feed Rates

Introduction of suspension and solution plasma spraying led to a breakthrough in the deposition of yttria-stabilized zirconia (YSZ) coatings and enabled preparation of new types of layers. However, their deposition with high feed rates needed, for example, for the deposition of thermal barrier coatings (TBCs) on large-scale components, is still challenging. In this study, possibility of high-throughput plasma spraying of YSZ coatings is demonstrated for the latest generation of high-enthalpy hybrid water-stabilized plasma (WSP-H) torch technology. The results show that microstructure of the coatings prepared by WSP-H may be tailored for specific applications by the choice of deposition conditions, in particular formulation of the liquid feedstock. Porous and columnar coatings with low thermal conductivity (0.5-0.6 W/mK) were prepared from commercial ethanol-based suspension. Dense vertically cracked coatings with higher thermal conductivity but also higher internal cohesion were deposited from suspension containing ethanol/water mixture and coarser YSZ particles. Spraying of solution formulated from diluted zirconium acetate and yttrium nitrate hexahydrate led also to the successful deposition of YSZ coating combining regions of porous and denser microstructure and providing both low thermal conductivity and improved cohesion of the coating. Enthalpy content, liquid-plasma interaction and coating buildup mechanisms are also discussed.     

Graphene fluoride: a stable stoichiometric graphene derivative and its chemical conversion to graphene

Stoichoimetric graphene fluoride monolayers are obtained in a single step by the liquid-phase exfoliation of graphite fluoride with sulfolane. Comparative quantum-mechanical calculations reveal that graphene fluoride is the most thermodynamically stable of five studied hypothetical graphene derivatives; graphane, graphene fluoride, bromide, chloride, and iodide. The graphene fluoride is transformed into graphene via graphene iodide, a spontaneously decomposing intermediate. The calculated bandgaps of graphene halides vary from zero for graphene bromide to 3.1 eV for graphene fluoride. It is possible to design the electronic properties of such two-dimensional crystals.     

Ultrastructural investigation of the spore-forming protist Nephridiophaga blattellae in the Malpighian tubules of the German cockroach Blattella germanica

Multinuclear plasmodia of the sporogenic protist Nephridiophaga blattellae are found intracellularly and in the lumen of the Malpighian tubules of the German cockroach Blattella germanica. Spore formation occurs only in the lumen. During sporogony, about 10-35 spores measuring 5.5x3.2 microm are endogenously formed within a plasmodium. Sporoblasts arise by the fusion of cisternae of the endoplasmic reticulum into a double membranous wall, which encloses a generative nucleus plus a portion of cytoplasm. Several somatic nuclei remain in the residual cytoplasm. Sporoblast and residual cytoplasm include mitochondria of the tubular type, endoplasmic reticulum, and many free ribosomes. During spore maturation, electron-dense wall material is deposited between the spore membranes, and the spores gain their typical oval, biconcave form. Freeze-etched spores reveal a small, central, cap-like structure, which may be the site where an infectious sporoplasm could emerge. Mature spores always have one nucleus, whereas early sporoblast stages with two small nuclei were found by transmission electron microscopy. Many nuclei of different developmental stages contain granules within the nuclear envelope. The systematic position of N. blattellae is unresolved. In certain respects it is reminiscent of Haplosporidia. However, the organisms of the two groups have different spore-forming processes and haplosporosomes are missing in the nephridiophagids. Therefore a new phylum might have to be erected for members of the family Nephridiophagidae.     

The Role of MAPK3/1 and AKT in the Acquisition of High Meiotic and Developmental Competence of Porcine Oocytes Cultured In Vitro in FLI Medium

The developmental potential of porcine oocytes cultured in vitro was remarkably enhanced in a medium containing FGF2, LIF and IGF1 (FLI) when compared to a medium supplemented with gonadotropins and EGF (control). We analyzed the molecular background of the enhanced oocyte quality by comparing the time course of MAPK3/1 and AKT activation, and the expression of genes controlled by these kinases in cumulus-oocyte complexes (COCs) cultured in FLI and the control medium. The pattern of MAPK3/1 activation in COCs was very similar in both media, except for a robust increase in MAPK3/1 phosphorylation during the first hour of culture in the FLI medium. The COCs cultured in the FLI medium exhibited significantly higher activity of AKT than in the control medium from the beginning up to 16 h of culture; afterwards a deregulation of AKT activity occurred in the FLI medium, which was not observed in the control medium. The expression of cumulus cell genes controlled by both kinases was also modulated in the FLI medium, and in particular the genes related to cumulus-expansion, signaling, apoptosis, antioxidants, cell-to-cell communication, proliferation, and translation were significantly overexpressed. Collectively, these data indicate that both MAPK3/1 and AKT are implicated in the enhanced quality of oocytes cultured in FLI medium.     

Biodiesel from rapeseed oil,methanol and KOH. 2. Composition of solution of KOH in methanol as reaction partner of oil

The composition of the solutions of solid KOH in methanol has been measured by means of determinating the content of water in the equilibrium mixture. The dependence of the equilibrium reaction extent ζ¹ and the concentration equilibrium constant Kc on the ratio of the initial amounts of methanol and KOH containing 0.164 and 16.27 wt‐% of water are determined and theoretically described. The concentration of CH₃O¯ ions can be calculated with these results. This value is very important for the course of the alkaline catalyzed methanolysis of rapeseed oil to biodiesel, because the methoxide ions are the true catalyst of such a transesterification.