Surface stress distribution in diamond crystals in diamond–silicon carbide composites

Diamond–silicon carbide composites were sintered at high temperature, up to 2273 K, and high pressure, up to 10 GPa. Raman microscopy was used to map stress distribution in diamond crystals on surfaces of the composites. Splitting of the triple degenerate band of diamond and frequency shifts of its components were used to calculate the magnitudes of stress. Those magnitudes varied with location and reached maximum values near crystals boundaries. Stress depended on the sintering temperature, pressure, and the crystal size and was attributed to differences in thermal expansion coefficients and bulk moduluses of diamond and silicon carbide.     

KRAS and EGFR Mutations Differentially Alter ABC Drug Transporter Expression in Cisplatin-Resistant Non-Small Cell Lung Cancer

Lung carcinoma is still the most common malignancy worldwide. One of the major subtypes of non-small cell lung cancer (NSCLC) is adenocarcinoma (AC). As driver mutations and hence therapies differ in AC subtypes, we theorized that the expression and function of ABC drug transporters important in multidrug resistance (MDR) would correlate with characteristic driver mutations KRAS or EGFR. Cisplatin resistance (CR) was generated in A549 (KRAS) and PC9 (EGFR) cell lines and gene expression was tested. In three-dimensional (3D) multicellular aggregate cultures, both ABCB1 and ABCG2 transporters, as well as the WNT microenvironment, were investigated. ABCB1 and ABCG2 gene expression levels were different in primary AC samples and correlated with specific driver mutations. The drug transporter expression pattern of parental A549 and PC9, as well as A549-CR and PC9-CR, cell lines differed. Increased mRNA levels of ABCB1 and ABCG2 were detected in A549-CR cells, compared to parental A549, while the trend observed in the case of PC9 cells was different. Dominant alterations were observed in LEF1, RHOU and DACT1 genes of the WNT signalling pathway in a mutation-dependent manner. The study confirmed that, in lung AC-s, KRAS and EGFR driver mutations differentially affect both drug transporter expression and the cisplatin-induced WNT signalling microenvironment.     

Simplified method for the determination oftrans monoenes in edible fats by TLC-GLC

Several modifications of an established thin-layer chromatography-gas-liquid chromatography (TLC-GLC) procedure for quantitatingtrans unsaturated fatty acids in edible fats are presented. These refinements considerably simplify the procedure without affecting accuracy. The modifications include: i) the use of pre-coated silica sheets, dynamically impregnated with Ag⁺, which allow separated bands to be cut off with a pair of scissors; and ii) the use of stearic acid in the deliberately combined saturated andtrans monounsaturated fatty acid methyl ester bands as an (endogenous) internal standard.Trans values thereby obtained agree favorably with the results from the conventional technique.     

Effect of aging on multifocal oscillatory potentials.

Multifocal oscillatory potentials (m-OPs) are thought to reflect rod-cone interactions. We examined the effect of age on the topography of the m-OP responses out to an eccentricity of 30 deg. Fifty-eight normal subjects were studied, aged between 13.6 and 58.8 yr. The data show a linear decrease in amplitude and a linear increase in latency with age, which is significant for most potentials. The decrease is uniform over the retina. These results suggest that an age-related impairment is occurring at or before the inner retina.     

Fine structural analysis of the morphological changes involved in the blanching, cooking, dehydration and rehydration of green bean pod tissue

Summary The influence of blanching and cooking on green bean pod tissue (Phaseolus vulgaris var. nanus L.) was studied by transmission electron microscopy and characteristic histological and cytological effects were recorded. The analysis of dehydraded and rehydrated samples (dehydration by'hot air, rehydration by boiling) showed that much of the shrinkage after dehydration can be compensated by water absorption during rehydration. The morphological appearance of boiled raw tissue, however, is not reached.

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Feinstrukturelle Untersuchungen am Hülsengewebe der Grünen Bohne nach Blanchieren, Kochen, De- und Rehydratisieren

Zusammenfassung Histologische und cytologische Veränderungen, die im Hülsengewebe der Grünen Bohne (Phaseolus vulgaris var. nanus L.) nach Blanchieren und Kochen auftreten, wurden mit Hilfe der Transmissionselektronenmikroskopie analysiert. Die feinstrukturelle Untersuchung warmluftgetrockneter und durch Kochen rehydratisierter Proben zeigte, daß die Gewebeveränderungen nach dem Trocknen zum großen Teil durch Wasseraufnahme rückgängig gemacht werden. Das morphologische Erscheinungsbild der gekochten Rohware wird jedoch nicht erreicht.

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Abbreviations ch chloroplast - cw cell wall - cy cytoplasm - i.sp. intercellular space - m mitochondrion - p pit - rer rough endoplasmic reticulum - st starch - v vacuole Dedicated to Prof. Dr. Gerhard Pfefferkorn on the occasion of his 65 ^th birthday     

Effects of small MoO3 additions on the properties of nickel catalysts for the steam reforming of hydrocarbons: II. Ni---Mo/Al2O3 catalysts in reforming, hydrogenolysis and cracking of n-butane

Addition of molybdenum to nickel catalysts has a favourable effect on their properties in the steam reforming of hydrocarbons. Some attempts were made to explain the mechanism of promoter action by determining the properties of such catalysts in hydrogenolysis and cracking reactions. With small amounts of promoter (≤0.5 wt.%) advantageneous changes in selectivity of steam reforming and disadvantageneous changes in n-butane hydrogenolysis were observed. The promoter does not affect practically the catalyst properties in n-butane cracking. The effect of molybdenum was compared with that of potassium promoter applied in the industry.     

Inorganic-organic nanocomposites based on sol-gel derived magnesium fluoride

Monodispersed magnesium fluoride nanoparticles are utilized for the first time to prepare transparent inorganic-organic nanocomposite materials with improved mechanical properties. The fluorolytic sol-gel synthesis route has been modified for the preparation of monodispersed magnesium fluoride nanoparticles with a size of 2-3 nm. MgF(2) particles are effectively stabilised against agglomeration by phosphonic acids, which strongly bind to the particles and lead to an increased compatibility of the inorganic particles with the organic polymers. This way, highly transparent nanocomposite materials with up to 20 wt% magnesium fluoride in different acrylates are obtained, featuring high dispersion of MgF(2) particles in the polymer matrix and an increased hardness by the factor of 2. The nature of interaction between phosphonic acids and magnesium fluoride is thoroughly investigated by IR and NMR showing a monodentate coordination of phosphonates to the particle's surface.     

The Wear Resistance of HVOF Sprayed Composite Coatings

The aim of the study was to determine the interactions between standard antiwear zinc dialkyldithiophosphate (ZDTP)-type additives and composite coatings containing hard phases of Al₂O₃, SiC, and TiN in the nickel matrix. The analysis was conducted for selected ceramic materials with different structures and different tribological behavior of ionic, covalent, and metallic bonds. The composite coatings were deposited on C45 steel using the high-velocity oxygen-fuel (HVOF) process. This process efficiently uses high kinetic energy and controlled thermal output to produce dense, low porosity coatings with highly predictable chemistries that are homogeneous in structure. The coatings can operate under harsh service conditions, because they are characterized by higher durability and higher wear and corrosion resistance. It was necessary to determine the interactions between the ZDTP-type antiwear additives (zinc dialkyldithiophosphates) and the coatings. The tribological properties of nickel and nickel-based composite coatings were examined by means of a T-01 M tester functioning in the ball-on-disc configuration during technically dry friction and boundary lubricated friction with lubricants containing 1% ZDTP. The comparative analysis confirmed different tribochemical activity and, accordingly, different tribological effectiveness of the nickel and nickel-based composite coatings during friction.     

Decomposition of MgSiN2 in nitrogen atmosphere

Magnesium silicon nitride MgSiN₂ was prepared by direct nitridation of Si/Mg₂Si/Mg/Si₃N₄ powder compact in a temperature range 1350-1420 °C. The thermal stability examination showed that MgSiN₂ is stable up to 1400 °C at 0.1 MPa N₂ pressure. The activation energy of decomposition of MgSiN₂ calculated from the temperature dependence of mass loss in the range of 1400-1650 °C is ΔH = 501 kJ mol⁻¹. The time dependence and nitrogen pressure dependence of MgSiN₂ decomposition was also investigated at constant temperature. MgSiN₂ is stable at 1560 °C in 0.6 MPa nitrogen atmosphere. Using these experimental data together with the heat capacity published in a literature the Gibbs energy of formation of MgSiN₂ was calculated in a temperature range 25-2200 °C.