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The leaching behavior of hemimorphite in neutral solution (NH4 +-Cl--H2O) was investigated at high temperature (T > 100°C) under a range of experimental conditions. Thermodynamic calculations indicate that the tendency of dehydration of silica gel is significantly enhanced with the increasing temperature. It was shown that the temperature, ammonium chloride concentration, or L/S ratio increased resulted in greater leaching efficiency. The following optimized leaching conditions were obtained: stirrer speed 400r/min, NH4Cl concentration 5.5M, L/S ratio 9mL/g at 160°C for 3h. Under these optimized conditions, the average leaching yield of zinc was 97.82%. The silicon was converted to quartz and remained in the residue. This process can be used to dispose willemite and hemimorphite as it solves the problem of silica gel dehydration.

In metallic glasses (MGs), a clear correlation has been established between plasticity and the Poisson's ratio. Such a correlation between the two distinctive macroscopic mechanical properties is challenging to explain from a microstructure perspective. We studied the microstructural origin of the Poisson's ratio and plasticity criterion in various MGs and find a correlation between the relative concentration of flow units and Poisson's ratio: the MGs with higher concentration of flow units show a larger Poisson's ratio and better plasticity. We have explained the empirical correlation between ductility and the Poisson's ratio based on microscopic flow units in MGs. [ABSTRACT FROM AUTHOR]

It has been postulated that metallic glasses, in contrast to their crystalline counterparts, exhibit nano-scale structural heterogeneity which is crucial for understanding the long-standing issues of relaxations and deformation of glasses. We fabricate micrometer scale metallic glassy fibers (MGFs) with different diameters and structural configurations, and find that the thinner MGFs cooled down with faster cooling rates have smaller superconducting transition temperatures and wider transition widths. We show that the superconducting properties correlate with the heterogeneous microstructure of metallic glasses and can be used as a novel way to experimentally characterize the structural heterogeneity of metallic glasses. [ABSTRACT FROM AUTHOR]

We characterize the evolution of flow units associated with the flow 'defects' in metallic glass by monitoring the fictive temperature change of a typical metallic glass upon isothermal annealing below its glass transition temperature. The correlations between the fictive temperature Tf, enthalpy change, and the concentration of flow units have been obtained. Such correlations help in understanding the evolution process of flow units, structural feature, and structural relaxation behaviors in metallic glasses, and can rationalize effects of the cooling rate, aging, and annealing on properties and structure of metallic glasses. [ABSTRACT FROM AUTHOR]

The unique thermoplastic forming ability of metallic glasses in their supercooled liquid state makes them the ideal embossing materials for miniature fabrication. However, the understanding and controlling of micro filling process that is crucial for miniature fabrication and their applications remain fundamental, yet presently unresolved issues. Here, the mold filling kinetics of a model Pd-based metallic glass in supercooled liquid state is studied using different Si micro molds with different channels. A universal kinetic equation, which can describe the filling kinetics of viscous metallic supercooled liquid in micro molds with irregular shapes, is obtained. [ABSTRACT FROM AUTHOR]

Tree peony (Paeonia section Moutan DC.) is an excellent ornamental plant, of which Paeonia ostii (P. ostii) has a high oil value. It is widely cultivated in China, but severe drought affects its growth. In this study, the effects of exogenous calcium on drought-induced damage of P. ostii were studied. The results showed that under drought stress, leaf water content showed a downward trend, while reactive oxygen species (ROS), relative electrical conductivity (REC), proline (Pro) content, and related antioxidant enzymes increased significantly. Spraying CaCl2 could effectively slow leaf wilting and water loss, induced an increase in enzyme activity of the antioxidant enzyme system, and reduced the accumulation of ROS caused by drought stress. Simultaneously, REC and Pro content could be alleviated, and the degree of cell membrane damage could be reduced. In addition, CaCl2 improved photosynthetic characteristics and chlorophyll fluorescence parameters. These results indicated that CaCl2 reduced the harmful effects of drought stress on the growth of P. ostii by regulating infiltration, activating photosynthesis, and enhancing the antioxidant system. These findings suggested that CaCl2 can be used to manage drought stress in P. ostii cultivation. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (∼8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light. [ABSTRACT FROM AUTHOR]

The glass transition and the microstructural characteristics of (Zr[sub 0.59]Ti[sub 0.06]Cu[sub 0.22]Ni[sub 0.13])[sub 100-x]Al[sub x] ( 10≤x≤16) bulk metallic glasses (BMG) are investigated as function of Al content. It is found that the Al content has strong effects on the glass transition, microstructure, and properties of the alloy. The marked increase of the Debye temperature and shear modulus with increasing Al content indicates that the different Al incorporations result in microstructural change in atomic short range of the BMG. The increase of the glass transition temperature with the increase Al content is consistent with the large variation of properties with increase of Al content. The change of the microstructure of the glass-forming alloy is responsible for the change of the properties. [ABSTRACT FROM AUTHOR]

Studies the pressure dependence of ultrasonic attenuation in Zr[sub 41]Ti[sub 14]Cu[sub 12.5]Ni[sub 10-x]Be[sub 22.5]C[sub x] bulk metallic glasses by using a pulse echo overlap method. Glass forming ability; Effects of carbon addition on changes of the alpha[1] and alpha[sub s].