Aqueous pathways for the formation of zinc oxide nanoparticles

We examine the effect of reactant concentrations, temperatures and feeding methods on the morphology of ZnO formed when reacting solutions of ZnSO 4 and NaOH. The catalytic effect of hydroxide in excess relative to the stoichiometric ratio is considered. It is shown that, having fixed other reaction conditions, the end-products, particle structures and size strongly depend on the mole ratio of the precursors. The presence of zinc salt hydroxide species was confirmed at sub-stoichiometric ratios in slightly acidic conditions. At the stoichiometric ratio both zinc hydroxide and zinc oxide are formed, while only zinc oxide forms in an excess of hydroxide. The method of feeding the reactants into the reaction vessel also has a strong influence on the end-product properties, as does the reaction temperature. By control of these parameters the specific surface area could be varied from 10 to 33 m 2 g-1, the particle shape could be varied from equiaxed, through to star-like and needle-like, and the particle size may be varied from 50 to over 300 nm. © 2011 The Royal Society of Chemistry

Synthetic dye decolorization by three sources of fungal laccase

Decolorization of six synthetic dyes using three sources of fungal laccase with the origin of Aspergillus oryzae, Trametes versicolor, and Paraconiothyrium variabile was investigated. Among them, the enzyme from P. variabile was the most efficient which decolorized bromophenol blue (100%), commassie brilliant blue (91%), panseu-S (56%), Rimazol brilliant blue R (RBBR; 47%), Congo red (18.5%), and methylene blue (21.3%) after 3 h incubation in presence of hydroxybenzotriazole (HBT; 5 mM) as the laccase mediator. It was also observed that decolorization efficiency of all dyes was enhanced by increasing of HBT concentration from 0.1 mM to 5 mM. Laccase from A. oryzae was able to remove 53% of methylene blue and 26% of RBBR after 30 min incubation in absence of HBT, but the enzyme could not efficiently decolorize other dyes even in presence of 5 mM of HBT. In the case of laccase from T. versicolor, only RBBR was decolorized (93%) in absence of HBT after 3 h incubation. © 2012 Forootanfar et al.; licensee BioMed Central Ltd

A case control study of acute leukemia risk factors in adults, Shiraz, Iran.

Abstract: Background: Leukemia is one of the most common cancers in Iran. Few studies have focused on identifying the causative factors for leukemia. This implies the necessity of this case-control study. This study was undertaken to identify possible risk factors associated with leukemia. Materials and Methods: In a case-control study matched by age and sex. 100 leukemic patients admitted in hematology wards in Namazee Hospital affiliated to Shiraz University of Medical Sciences were enrolled. Control group compromised 100 ..

The alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers mediate cell attachment to distinct sites on laminin.

This study was undertaken to determine the roles of individual alpha/beta 1 integrin heterodimers in promoting cellular interactions with the different attachment-promoting domains of laminin (LN). To do this, antibodies to the integrin beta 1 subunit or to specific integrin alpha subunits were tested for effects on cell attachment to LN, to elastase fragments E1-4 and E1, derived from the short arms and core of LN's cruciform structure, and to fragment E8 derived from the long arm of this structure. The human JAR choriocarcinoma cells used in this study attached to LN and to fragments E1 and E8. Attachment to E1-4 required a much higher substrate coating concentration, suggesting that it is a poor substrate for JAR cell attachment. The ability of cells to attach to different LN domains suggested the presence of more than one LN receptor. These multiple LN receptors were shown to be beta 1 integrin heterodimers because antibodies to the integrin beta 1 subunit inhibited attachment of JAR cells to LN and its three fragments. To identify the individual integrin alpha/beta 1 heterodimers that mediate interactions with these LN domains, mAbs specific for individual beta 1 heterodimers in human cells were used to study JAR cell interactions with LN and its fragments. An anti-alpha 6/beta 1-specific mAb, GoH3, virtually eliminated cell attachment to E8 and partially inhibited attachment to E1 and intact LN. Thus the major alpha 6/beta 1 attachment domain is present in fragment E8. An alpha 1/beta 1-specific mAb (S2G3) strongly inhibited cell attachment to collagen IV and partially inhibited JAR attachment to LN fragment E1. Thus, the alpha 1/beta 1 heterodimer is a dual receptor for collagen IV and LN, interacting with LN at a site in fragment E1. In combination, the anti-alpha 1- and anti-alpha 6-specific antibodies completely inhibited JAR cell attachment to LN and fragment E1. Thus, the alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers each function as LN receptors and act together to mediate the interactions of human JAR choriocarcinoma cells with LN

On the formation of nanocrystalline active zinc oxide from zinc hydroxide carbonate

The decomposition of zinc hydroxide carbonate, Zn5(CO 3)2(OH)6 (ZHC), into the high surface area form of ZnO known as "active zinc oxide" is examined. In particular, the nucleation and evolution of the ZnO nanocrystals is of interest as the size of these particles controls the activity of the product. The decomposition process was studied using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and BET surface area measurements. At about 240°C ZHC decomposes to porous ZnO in a single step. The product material has a specific surface area in the range of 47-65 m 2 g-1 and initially has a crystallite size that is of the order of 10 nm. A further increase in temperature, however, causes the particles to coarsen to over 25 nm in diameter. In principle, the coarsening phenomenon may be interrupted to control the particle size. © Springer Science+Business Media 2014

Zinc oxide : new insights into a material for all ages

University of Technology, Sydney. Faculty of Science.Zinc oxide is an important material industrially and scientifically. It has a long history dating back to more than four thousand years ago. It has applications in rubber production, cosmetics, pigments and ceramics. The properties of zinc oxide such as porosity, specific surface area and optical properties change as a result of changing the synthetic method and process conditions. The suitability of ZnO for different applications depends on the properties of the material, which in turn are influenced by synthetic routes. Knowledge of the processes underpinning the various synthetic techniques is key to understanding the properties of the ZnO end-product. In this work, various synthetic techniques have been investigated that may be amenable to large-scale production. The resultant materials were studied and important insights were obtained. For example, it was found that the precursor materials and method of processing for the production of zinc oxide have important roles in controlling the properties of the product such as specific surface area, crystal morphology, particle size and amount of surface hydroxyl groups embedded in the product. In single-stage production methods, zinc oxide is precipitated directly from a zinc solution. Influences of reaction temperature, concentration of the reactants and feeding techniques on the properties of the products were determined. In multi-stage routes, intermediate zinc-bearing materials including zinc peroxide and zinc hydroxy carbonate, sulphate, chloride, nitrate and acetate were synthesised. These intermediate materials were then used as precursors for the formation of zinc oxide particles. Relationships between the properties of the precursor zinc-containing compound and the end-product zinc oxide were studied and unexpected results were obtained. For example, it was shown that specific surface area of the zinc oxide product depends significantly on the precursor material from which it is produced. Techniques were investigated that can produce multiple important zinc-bearing compounds and it was found that it could be engineered by selection of the appropriate precursors and process conditions

On the reactivity of zinc hydroxide acetate dihydrate in ethanol

Zinc hydroxide acetate dihydrate, Zn5(OH)8(CH 3CO2)2·2H2O, reacts in ethanol at room temperature to yield a mixture of zinc oxide and anhydrous zinc acetate. The process is driven by dehydration of the starting salt. Dehydration of Zn5(OH)8(CH3CO2) 2·2H2O also occurs when it is heated in air, but the product obtained in that case depends on the heating rate, environment and temperature. For example, when it is kept in a sealed silica capillary at 100 °C, Zn5(OH)8(CH3CO2) 2·1.5H2O is formed after 15 min, whereas treatment in the range 90-100°C in an open environment results in the formation of anhydrous zinc hydroxide acetate. Heating of any of these products further causes their decomposition to Zn(CH3CO2)2 and ZnO. The coordination bonding mode of the acetate groups in the anhydrous layered zinc hydroxide acetate prepared by reaction with ethanol was studied by using solid-state NMR spectroscopy. The presence of chelating, unidentate and bidentate bridging modes for the carbonyl carbon atom was revealed, but there was no evidence for the inclusion of ethanol in the resultant structure. Therefore, the reaction in ethanol offers a convenient strategy to prepare anhydrous zinc hydroxide acetate and/or zinc oxide, because it avoids the sensitivity of the thermally induced dehydroxlation process to time, temperature and environment. Decomposition of zinc hydroxide acetate dihydrate in ethanol can be exploited to generate ZnO nanoparticles at room temperature. The mechanism involves the removal of waters of hydration and the formation of Zn5(OH)8(CH3CO2)2 followed by the generation of Zn(CH3CO)2 and ZnO. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Drosophila Adducin facilitates phase separation and function of a conserved spindle orientation complex

Asymmetric cell division (ACD) allows stem cells to generate differentiating progeny while simultaneously maintaining their own pluripotent state. ACD involves coupling mitotic spindle orientation with cortical polarity cues to direct unequal segregation of cell fate determinants. In Drosophila neural stem cells (neuroblasts; NBs), spindles orient along an apical-basal polarity axis through a conserved complex of Partner of Inscuteable (Pins; human LGN) and Mushroom body defect (Mud; human NuMA). While many details of its function are well known, the molecular mechanics that drive assembly of the cortical Pins/Mud complex remain unclear, particularly with respect to the mutually exclusive Pins complex formed with the apical scaffold protein Inscuteable (Insc). Here we identify Hu li tai shao (Hts; human Adducin) as a direct Mud-binding protein, using an aldolase fold within its head domain (HtsHEAD) to bind a short Mud coiled-coil domain (MudCC) that is adjacent to the Pins-binding domain (MudPBD). Hts is expressed throughout the larval central brain and apically polarizes in mitotic NBs where it is required for Mud-dependent spindle orientation. In vitro analyses reveal that Pins undergoes liquid-liquid phase separation with Mud, but not with Insc, suggesting a potential molecular basis for differential assembly mechanics between these two competing apical protein complexes. Furthermore, we find that Hts binds an intact Pins/Mud complex, reduces the concentration threshold for its phase separation, and alters the liquid-like property of the resulting phase separated droplets. Domain mapping and mutational analyses implicate critical roles for both multivalent interactions (via MudCC oligomerization) and protein disorder (via an intrinsically disordered region in Hts; HtsIDR) in phase separation of the Hts/Mud/Pins complex. Our study identifies a new component of the spindle positioning machinery in NBs and suggests that phase separation of specific protein complexes might regulate ordered assembly within the apical domain to ensure proper signaling output

Computational Simulation of Shock-Bubble Interaction, using a Front-Tracking/Ghost Fluid Method

A front tracking/ghost fluid method was used to simulate fluid interfaces in a shock–bubble interaction problem. The method captures fluid interfaces, using explicit front-tracking and defines interface conditions, using the ghost-fluid method. In order to demonstrate the accuracy and the capability tracking of the approach used, an air-helium and anair-R22 shock-bubble interaction cases were simulated. The computational results were compared with reliable experimental and computational studies, showing close agreements