Adhesion and friction properties of hydrogenated amorphous carbon films measured by atomic force microscopy

Atomic force microscopy has been used to measure adhesion and friction forces at the interface between an oxidized metal probe tip and amorphous carbon films of varying hydrogen contents (12.3–39.0 atomic percent hydrogen). The interface of an oxide surface and a hard carbon coating models the unlubricated head-disk interface of current hard disk products. Adhesion forces normalized by the radius of curvature of the contacting tip range from 1.09 to 8.53 N/m. Coefficients of friction values, measured as the slope of the friction versus load plot, range from 0.33 to 0.87. A trend of increasing adhesion forces and coefficients of friction is observed for increasing hydrogen content in the films. We attribute the increase in adhesion and friction to increases in the surface free energy of the carbon films with the incorporation of hydrogen.     

Optimisation of supercritical CO2 extraction of grape seed oil using response surface methodology

The aim of this study was to use waste from the wine production process with special accent on grape seeds and new green technology. Supercritical CO₂ was considered as a green solvent in extraction of grape seed oil. The effects of different extraction process parameters on oil yield and antioxidant activity were investigated. Extraction optimisation was conducted using response surface methodology (RSM). Extraction pressure has proven to be the most significant factor influencing oil yield and antioxidant activity (P < 0.0001). The optimal conditions for obtaining the highest oil yield and antioxidant activity within the experimental range of the variables studied were at extraction pressure of 400 bar and temperature of 41 °C. Under these optimal conditions, the predicted extraction oil yield was 14.49% and DPPH 37.07%. Applying this green extraction method, the oil from grape seeds was totally extracted. The produced oil was of satisfactory quality, and the content of α‐tocopherol in obtained grape seed oil at optimal extraction conditions was 36.05 mg kg^?1.     

A dysfunctional desmin mutation in a patient with severe generalized myopathy

Mice lacking desmin produce muscle fibers with Z disks and normal sarcomeric organization. However, the muscles are mechanically fragile and degenerate upon repeated contractions. We report here a human patient with severe generalized myopathy and aberrant intrasarcoplasmic accumulation of desmin intermediate filaments. Muscle tissue from this patient lacks the wild-type desmin allele and has a desmin gene mutation encoding a 7-aa deletion within the coiled-coil segment of the protein. We show that recombinant desmin harboring this deletion cannot form proper desmin intermediate filament networks in cultured cells, nor is it able to assemble into 10-nm filaments in vitro. These findings provide direct evidence that a mutation in desmin can cause human myopathies.     

Capacitation and the acrosome reaction in marsupial spermatozoa

Although yet to be established definitively, it appears that marsupial spermatozoa require a process of capacitation and that the mechanisms involved may be quite different between the Australian and American species. For Australian species, failure to induce this functional event in culture has meant that in vitro fertilization (IVF) is yet to be achieved. However, in the American species with paired spermatozoa, IVF and subsequent embryo development have been obtained under quite simple culture conditions. Our understanding of the interactions of marsupial spermatozoa with the female tract, and in particular the oviduct, the most likely site of capacitation, is discussed. Although the acrosome reaction (AR) is an equally critical event in marsupial fertilization it appears to be regulated quite differently. The uniquely stable character of the marsupial acrosome is examined as well as our current understanding of the regulation of the marsupial sperm AR in vivo and in vitro.     

Atomic Force Microscopy and X-ray Photoelectron Spectroscopy Investigation of the Onset of Reactions on Alkali Silicate Glass Surfaces

Atomic force microscopy was used to measure forces acting on a sharp tungsten tip as it was brought into contact with silica and 30 mol% binary alkali silicate glasses. Experiments were performed in controlled atmospheres and under vacuum. Attractive forces and liquid-layer thicknesses were found to vary markedly between the glasses, and heterogeneity was observed on the binary alkali silicates analyzed in vacuo . Air or wet carbon dioxide exposure resulted in the penetration of the tip into a soft surface layer on the alkali silicates. In addition, liquid layer formation on the alkali silicates was found to be promoted by exposure to water vapor in the order lithium < sodium < potassium. X-ray photoelectron spectroscopy indicated that reaction between the potassium silicate surface and water vapor occurred on exposure to only 10⁻⁴ torr (1 torr = 1.33 × 10² Pa) water. Surface segregation and leaching of potassium occurred under the same conditions.     

Preface

Preface

Preface     

Effects of supercritical CO2 extraction parameters on soybean oil yield

A series of operational parameters of supercritical fluid extraction of soybean oil (pressure: 300–500 bar, temperature: 40–60 °C, CO₂ mass flow rate: 0.194–0.436 kg/h and characteristic particle size: 0.238–1.059 mm) were investigated in a laboratory scale apparatus. The results show that the extraction yields were significantly affected by applied operational extraction parameters. The increase in pressure, temperature and solvent flow rate improved the extraction yield. The extraction yield increased as the particle size decreased depending on decreasing intra-particle diffusion resistance. To describe the extraction process Sovova's model was used and very good agreement with the experimental results was obtained. Based on the experimental data the internal and external mass transfer coefficients were estimated. To explore the influence of the extractor size on this process, soybean samples were extracted using different extraction basket volumes (0.2 L and 5 L) and related model parameters were examined. The mass transfer coefficient in the fluid phase increased with the increase in extractor size, while the mass transfer coefficient in the solid phase was independent of the extractor size.