Use of centrifugal-gravity concentration for rejection of talc and recovery improvement in base-metal flotation

The possibility of using a centrifugal-gravity concentrator to reject Mg-bearing minerals and minimize metal losses in the flotation of base metals was evaluated. Sample characterization, batch scoping tests, pilot-scale tests, and regrind-flotation tests were conducted on a Ni flotation tailings stream. Batch tests revealed that the Mg grade decreased dramatically in the concentrate products. Pilot-scale testing of a continuous centrifugal concentrator (Knelson CVD6) on the flotation tailings revealed that a concentrate with a low mass yield, low Mg content, and high Ni upgrade ratio could be achieved. Under optimum conditions, a concentrate at 6.7% mass yield was obtained with 0.85% Ni grade at 12.9% Ni recovery and with a low Mg distribution (1.7%). Size partition curves demonstrated that the CVD also operated as a size classifier, enhancing the rejection of talc fines. Overall, the CVD was capable of rejecting Mg-bearing minerals. Moreover, an opportunity exists for the novel use of centrifugal-gravity concentration for scavenging flotation tailings and/or after comminution to minimize amount of Mg-bearing minerals reporting to flotation.     

Optimization of Cutting Parameters for Face Milling Titanium Alloy Using MQL

When using MQL as a cooling technique, many parameters have to be adjusted. The Taguchi method was used in this study to investigate the cutting characteristics of face milling of titanium alloys using PVD-coated inserts. To find the optimal volume removed and surface roughness, an orthogonal array, the signal-to-noise （S/N） ratio and the analysis of variance （ANOVA） were employed. The optimum cutting parameters was obtained. Throughout this study, it was found that the feed rate is the most influencing cutting parameter in the face milling of titanium alloys.     

Complete structure and expression in transfected cells of high affinity IgE receptor

The high-affinity receptor for immunoglobulin E, Fc epsilon RI, is found exclusively on mast cells and basophils. When multivalent allergens bind to the receptor-bound IgE, the consequent aggregation of the receptors leads to the release of mediators responsible for allergic symptoms. In rodents Fc epsilon RI is a tetrameric complex of non-covalently attached subunits: one IgE-binding alpha subunit, one beta subunit and a dimer of disulphide-linked gamma subunits. Complementary DNA encoding the alpha and the beta subunits has recently been isolated, but expression of IgE-binding by transfected cells has not yet been achieved. Here we report the cloning of cDNA for the gamma subunit, and propose a model for the alpha beta gamma 2 tetramer which accounts for many of the structural features of the receptor. The rodent receptor on the surface of COS 7 cells was expressed only when the cDNAs for all three subunits were cotransfected. Successful expression of human IgE receptors should now be possible, eventually to permit the detailed analysis of the human IgE-receptor interaction and assist the search for therapeutically effective inhibitors.     

伊朗Lorestan省粉虱物种多样性研究（半翅目：粉虱科）

粉虱（半翅目：粉虱科）是一类通过吸食植物体汁和传播病毒危害农作物的害虫。本文研究了伊朗西部Lorestan省的这一类具重要经济意义的粉虱类群物种多样性，调查了16属27种粉虱，进行了种类鉴定研究，包括种的异名和分布。     

Physicochemical characteristics of various milk samples available in Pakistan

We report physicochemical characteristics of various kinds of liquid milk commercially available in Pakistan in comparison with those of fresh natural milk from animals. Milk samples were collected from local markets at Peshawar, Pakistan, and analyzed for their physical features, including moisture, total solids, specific gravity, conductivity, viscosity and titratable acidity （lactic acid equivalent）, and chemical components and macro-minerals, including total protein, casein, lactose, ash and minerals （Na, K and Mg）. These items were compared with the physicochemical characteristics of the fresh natural milk samples from buffalo, cow and goat. The results were also compared with reported nutritional quality of milk from various countries and World Health Organization （WHO） standards. We found that all the physical features and chemical components of commercially available milk in Pakistan markets meet WHO＇s requirements, except for Na, K, Ca and Mg, which are below the standards.     

Antibacterial and antifungal activities of different parts of Tribulus terrestris L. growing in Iraq

Antimicrobial activity of organic and aqueous extracts from fruits, leaves and roots of Tribulus terrestris L., an Iraqi medicinal plant used as urinary anti-infective in folk medicine, was examined against I l species of pathogenic and non-pathogenic microorganisms： Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Corynebacterium diphtheriae, Escherichia coli, Proteus vulgaris, Serratia marcescens, Salmonella typhimurium, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans using microdilution method in 96 multiwell microtiter plates. All the extracts from the different parts of the plant showed antimicrobial activity against most tested microorganisms. The most active extract against both Gram-negative and Gram-positive bacteria was ethanol extract from the fruits with a minimal inhibitory concentration （MIC） value of 0.15 mg/ml against B. subtilis, B. cereus, P. vulgaris and C. diphtheriae. In addition, the same extract from the same plant part demonstrated the strongest antifungal activity against C. albicans with an MIC value of 0.15 mg/ml.     

S-glutathionylation uncouples eNOS and regulates its cellular and vascular function

Endothelial nitric oxide synthase (eNOS) is critical in the regulation of vascular function, and can generate both nitric oxide (NO) and superoxide (O(2)(?-)), which are key mediators of cellular signalling. In the presence of Ca(2+)/calmodulin, eNOS produces NO, endothelial-derived relaxing factor, from l-arginine (l-Arg) by means of electron transfer from NADPH through a flavin containing reductase domain to oxygen bound at the haem of an oxygenase domain, which also contains binding sites for tetrahydrobiopterin (BH(4)) and l-Arg. In the absence of BH(4), NO synthesis is abrogated and instead O(2)(?-) is generated. While NOS dysfunction occurs in diseases with redox stress, BH(4) repletion only partly restores NOS activity and NOS-dependent vasodilation. This suggests that there is an as yet unidentified redox-regulated mechanism controlling NOS function. Protein thiols can undergo S-glutathionylation, a reversible protein modification involved in cellular signalling and adaptation. Under oxidative stress, S-glutathionylation occurs through thiol-disulphide exchange with oxidized glutathione or reaction of oxidant-induced protein thiyl radicals with reduced glutathione. Cysteine residues are critical for the maintenance of eNOS function; we therefore speculated that oxidative stress could alter eNOS activity through S-glutathionylation. Here we show that S-glutathionylation of eNOS reversibly decreases NOS activity with an increase in O(2)(?-) generation primarily from the reductase, in which two highly conserved cysteine residues are identified as sites of S-glutathionylation and found to be critical for redox-regulation of eNOS function. We show that eNOS S-glutathionylation in endothelial cells, with loss of NO and gain of O(2)(?-) generation, is associated with impaired endothelium-dependent vasodilation. In hypertensive vessels, eNOS S-glutathionylation is increased with impaired endothelium-dependent vasodilation that is restored by thiol-specific reducing agents, which reverse this S-glutathionylation. Thus, S-glutathionylation of eNOS is a pivotal switch providing redox regulation of cellular signalling, endothelial function and vascular tone.     

Atomic model of a myosin filament in the relaxed state

Contraction of muscle involves the cyclic interaction of myosin heads on the thick filaments with actin subunits in the thin filaments. Muscles relax when this interaction is blocked by molecular switches on either or both filaments. Insight into the relaxed (switched OFF) structure of myosin has come from electron microscopic studies of smooth muscle myosin molecules, which are regulated by phosphorylation. These studies suggest that the OFF state is achieved by an asymmetric, intramolecular interaction between the actin-binding region of one head and the converter region of the other, switching both heads off. Although this is a plausible model for relaxation based on isolated myosin molecules, it does not reveal whether this structure is present in native myosin filaments. Here we analyse the structure of a phosphorylation-regulated striated muscle thick filament using cryo-electron microscopy. Three-dimensional reconstruction and atomic fitting studies suggest that the 'interacting-head' structure is also present in the filament, and that it may underlie the relaxed state of thick filaments in both smooth and myosin-regulated striated muscles over a wide range of species.     

Effects of -NO2 and -NH2 functional groups in mixed-linker Zr-based MOFs on gas adsorption of CO2 and CH4

This study was undertaken to evaluate the effects of mixing BDC-NO_2 and BDC-NH_2 linkers in the synthesis of Zrbased metal organic frameworks(Zr-MOFs) on their adsorption and separation of CO_2 and CH_4. Ui O-66 with single or binary-NO_2 and-NH2 samples were synthesized under solvothermal conditions and activated by solvent exchanging using methanol. Structural analyses of the materials were conducted using FTIR, XRD, TGA,SEM,1 HNMR and N2 adsorption/desorption techniques and adsorption of CO_2 and CH_4 at high pressures and different temperatures(273 and 298 K) was investigated. It was found that Ui O-66-NH2 exhibited higher CO_2 and CH_4 adsorption capacities than those of Ui O-66-NO_2. Addition of-NH_2 functional group in Ui O-66-NO_2 could enhance CO_2 and CH_4 adsorption due to the extra CO_2 adsorption sites of-NH_2 functional groups. Addition of-NO_2 functional group to Ui O-66-NH2 at a low loading could also increase CO_2 and CH_4 adsorption, however,a high loading of NO_2 functional group to Ui O-66-NH2 would result in decreased adsorption.     

Diffusion mechanism in molten salt baths during the production of carbide coatings via thermal reactive diffusion

The diffusion mechanism of carbide-forming elements from a molten salt bath to a substrate surface was studied in this research, with particular focus on the processes occurring in the molten bath at the time of coating. Metal, oxide, and metal-oxide baths were investigated, and the coating process was performed on H13 steel substrates. Scanning electron microscopy and electron-probe microanalysis were used to study the coated samples and the quenched salt bath. The thickness of the carbide coating layer was 6.5 ±0.5, 5.2 ±0.5, or 5.7 ±0.5 μm depending on whether it was deposited in a metal, oxide, or metal-oxide bath, respectively. The phase distribution of vanadium-rich regions was 63%, 57%, and 74% of the total coating deposited in metal, oxide, and metal-oxide baths, respectively. The results obtained using the metal bath indicated that undissolved suspended metal particles deposited onto the substrate surface. Then, carbon subsequently diffused to the substrate surface and reacted with the metal particles to form the carbides. In the oxide bath, oxide powders dissolved in the bath with or without binding to the oxidative structure (Na₂O) of borax; they were then reduced by aluminum and converted into metal particles. We concluded that, in the metal and oxide baths, the deposition of metal particles onto the sample surface is an important step in the formation of the coating.