Application of ultrasonic methods to determine elastic anisotropy of polycrystalline copper processed by equal-channel angular pressing

Anisotropy of elastic properties of ultrafine-grained polycrystalline copper after one, two and four passes of equal-channel angular pressing (ECAP) is investigated by means of ultrasonic methods. For each material, Young’s and shear moduli in the principal processing directions are evaluated and the symmetry and orientation of the anisotropy are identified. The relation between the determined symmetry and the processing mechanisms is discussed. It is shown that the material after one and two passes of ECAP exhibits a measurable anisotropy, while the material after the fourth pass behaves isotropically. Within the discussion, it is shown that the origin of the observed anisotropy may be attributed to the spatial arrangement of grain boundaries rather than to the crystallographic texture. In the light of this conclusion, the obtained results correspond well with optical and transmission electron microscopy observations of the microstructures of ECAPed materials documented in the literature.     

Interfacial Properties of Carbon–Rubber Interfaces Investigated via Indentation Pull-Out Tests and the JKR Theory

Properties of the interface between the filler and the matrix of a composite material draw research attention due to their contributions to the overall properties of the material, especially when the filler and the matrix differ significantly from each other. The work reported in this paper investigates the interface between amorphous carbon and a cross-linked synthetic natural rubber. The interface was experimentally simulated with the surfaces of a sputtering-coated carbon on a spherical Al₂O₃ tip and a flat synthetic natural rubber sample. Step-loading and pull-out tests with a micro-/nano-indentation instrument were conducted. Fully relaxation of the samples occurred during both test procedures. The penetration depth, applied load, and experimental time were recorded during each test. The Johnson–Kendall–Roberts theory was used to analyze the data at the initial point (step-loading) and the final surface separation point (pull-out) to obtain the initial equivalent modulus, infinite equivalent modulus, work of adhesion, and the average normal interfacial strength at separation. It is found that the pull-out force and the work of adhesion depend on the unloading rate, but the infinite equivalent modulus and the average interfacial strength in the normal direction of the carbon–rubber interfaces are independent of the unloading rate in current experimental domain.     

Application of succinylated sugarcane bagasse as adsorbent to remove methylene blue and gentian violet from aqueous solutions - Kinetic and equilibrium studies

In a previous work, succinylated sugarcane bagasse (SCB 2) was prepared from sugarcane bagasse (B) using succinic anhydride as modifying agent. In this work the adsorption of cationic dyes onto SCB 2 from aqueous solutions was investigated. Methylene blue, MB, and gentian violet, GV, were selected as adsorbates. The capacity of SCB 2 to adsorb MB and GV from aqueous single dye solutions was evaluated at different contact times, pH, and initial adsorbent concentration. According to the obtained results, the adsorption processes could be described by the pseudo-second-order kinetic model. Adsorption isotherms were well fitted by Langmuir model. Maximum adsorption capacities for MB and GV onto SCB 2 were found to be 478.5 and 1273.2 mg/g, respectively.     

Synthesis and characterisation of a mesoporous carbon/calcium borohydride nanocomposite for hydrogen storage

Borohydrides with high hydrogen content are being extensively studied as potential hydrogen storage systems placing particular emphasis on upturning their unfavourable kinetic and thermodynamic properties which give rise to significantly high dehydrogenation temperatures and slow hydrogen release far away from the desired application window. In this work the encapsulation of Ca(BH₄)₂ particles in the pores of a CMK-3 type ordered mesoporous carbon scaffold by wet chemistry routes, also employing the use of TiCl₃ as a catalyst, is shown to have a beneficial effect on the hydrogen desorption profile of the bulk hydride by shifting its decomposition to noticeable lower temperatures.     

Calcium-independent phospholipase A2 in isolated rabbit ventricular myocytes

We characterized phospholipase A₂ (PLA₂) activity in isolated rabbit ventricular myocytes with respect to subcellular distribution, substrate specificity, and Ca²⁺ dependency. Membrane-associated PLA₂ was found to be an order of magnitude greater than cytosolic PLA₂. Ventricular myocyte PLA₂ activity was enhanced following protease-activated receptor stimulation with thrombin and was found to be largely Ca²⁺-independent and selective for phospholipid substrates containing arachidonic acid at the sn-2 position. Immunoblot analysis using an antibody to cytosolic Ca²⁺-independent PLA₂ from Chinese hamster ovary cells recognized a membrane-associated protein with a molecular mass of approximately 80 kDa; however, differences in pH optima, response to inhibitors, and substrate selectivity of membrane-associated and cytosolic PLA₂ activity suggest the presence of multiple Ca²⁺-independent PLA₂. Pretreatment with bromoenol lactone, a specific inhibitor of Ca²⁺-independent PLA₂, significantly attenuated membrane-associated and cytosolic PLA₂ in unstimulated and thrombin-stimulated myocytes. Pretreatment with methyl arachidonyl fluorophosphonate, mepacrine, or dibucaine had no significant effect on PLA₂ activity under all conditions tested. Ventricular myocyte PLA₂ activity was significantly inhibited by ATP, GTP, and their nonhydrolyzable analogs and was regulated by protein kinase C activity. These studies demonstrate the presence of one or more unique membrane-associated Ca²⁺-independent PLA₂ in isolated ventricular myocytes that exhibit a preference for phospholipids with arachidonate at the sn-2 position and that are activated by thrombin stimulation.     

Confirmatory factor analysis of combined Wechsler Adult Intelligence Scale—Revised and Wechsler Memory Scale—Revised scores in a healthy community sample.

This study examined the joint factor structure of the Wechsler Adult Intelligence Scale—Revised (D. Wechsler, 1981) and Wechsler Memory Scale—Revised (D. Wechsler, 1987) in a sample of 399 healthy young adults (206 women and 193 men) recruited for a normative study in Sydney, Australia: the Macquarie University Neuropsychological Normative Study. Using confirmatory factor analysis, the authors contrasted alternative models of ability in the respective Wechsler scales, focusing in particular on hypotheses relating to memory function. The best-fitting solution comprised a model representing Verbal Comprehension, Perceptual Organization, Attention-Concentration, Verbal Memory and Visual Memory. The results are discussed in terms of the incremental validity of ability assessment, potential for improvement in model-fit, and implications for professional practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

HYDROMETALLURGY OF STRATEGIC METALS

ABSTRACT

This paper gives a short overview of the importance of solvent extraction in the production and recycling of strategic metals. Both the present situation and possible developments are considered. The use of solvent extraction in the processing of powdered metal-containing materials with tailor-made characteristics is also discussed as it is attracting increasing attention.     

Influence of Social Media Use on Discussion Network Heterogeneity and Civic Engagement: The Moderating Role of Personality Traits

Using original national survey data, we examine how social media use affects individuals' discussion network heterogeneity and their level of civic engagement. We also investigate the moderating role of personality traits (i.e., extraversion and openness to experiences) in this association. Results support the notion that use of social media contributes to heterogeneity of discussion networks and activities in civic life. More importantly, personality traits such as extraversion and openness to experiences were found to moderate the influence of social media on discussion network heterogeneity and civic participation, indicating that the contributing role of social media in increasing network heterogeneity and civic engagement is greater for introverted and less open individuals.     

Design of a hybrid glass composite anchor for LNG cargo containment systems

Large cryogenic container for liquefied natural gas (LNG) should be joined to the inner hull of a ship. The minimum heat inflow, due to the large temperature difference between the LNG cargo container and inner hull, can induce considerable heat flux through the joined area.In this work, a hybrid composite anchor composed of two stainless steel caps and a glass fiber composite body was developed and optimized for strength, thermal stress and heat loss of the anchor. The stainless steel caps were adhesively bonded to the top and bottom areas of the glass composite body. The top stainless cap was then welded to the two stainless steel membranes, and the flange of the bottom stainless steel cap was bolt-fastened to the inner hull of a ship.The static adhesive strength and impact characteristics between the stainless steel caps and glass composite body of the hybrid glass composite anchor at the cryogenic temperature were investigated with respect to adhesive thickness. Finally, the optimal design for the hybrid glass composite anchor for the cryogenic containment systems of a LNG ship was suggested.     

Aqueous extract of Hibiscus sabdariffa L. decelerates acetaminophen‐induced acute liver damage by reducing cell death and oxidative stress in mouse experimental models

BACKGROUND: Acetaminophen (AAP)‐induced oxidative stress can cause cell death to induce liver damage. The antioxidant effect of Hibiscus sabdariffa L. (HS) was shown in previous studies. In this study the effect of HS extract (HSE) on AAP‐induced liver injury in BALB/c mice was investigated. RESULTS: In vivo, BALB/c mice were fed orally with 200, 400 or 600 mg kg⁻¹ HSE for 2 weeks and then injected with 1000 mg kg⁻¹ AAP. Pretreatment with HSE decreased lipid peroxidation and increased catalase activity and glutathione level. It also decreased AAP‐induced liver injury, accompanied by decreased expression of pJNK, Bax and tBid in the liver. Additionally, HSE protected BALB/c normal liver cells from AAP‐induced damage in vitro. CONCLUSION: It has been demonstrated that HSE can protect the mouse liver from AAP‐induced injury and that the protective mechanism might involve decreasing oxidative stress and reducing cell death. Copyright © 2009 Society of Chemical Industry