Search

As-cast in-situ nanoparticle reinforced CuSn10Zn2Fe1.5Co0.5 (wt-%) alloy was selected as base metal (BM) and filler for welding. Butt joints were obtained by tungsten inert gas (TIG) welding. Microstructure of weld metal was characterised. Nanoparticles with an average diameter of about 5 nm are uniformly dispersed in the primary copper matrix in size of micro or nano scales for weld metal. A large number of nano grains with size of about 20 nm can be found in the weld metal as well. Mechanical properties of weld metal were comparable to those of heat-treated BM. Strengthening and toughening strategies for the weld metal were discussed through fabricating in-situ nanoparticles and nano grains in the weld metal., As-cast in-situ nanoparticle reinforced CuSn10Zn2Fe1.5Co0.5 (wt-%) alloy was selected as base metal (BM) and filler for welding. Butt joints were obtained by tungsten inert gas (TIG) welding. Microstructure of weld metal was characterised. Nanoparticles with an average diameter of about 5 nm are uniformly dispersed in the primary copper matrix in size of micro or nano scales for weld metal. A large number of nano grains with size of about 20 nm can be found in the weld metal as well. Mechanical properties of weld metal were comparable to those of heat-treated BM. Strengthening and toughening strategies for the weld metal were discussed through fabricating in-situ nanoparticles and nano grains in the weld metal.

Tremendous efforts towards improvement in the critical current density "Jc" of iron based superconductors (FeSCs), especially at relatively low temperatures and magnetic fields, have been made so far through different methods, resulting in real progress. Jc at high temperatures in high fields still needs to be further improved, however, in order to meet the requirements of practical applications. Here, we demonstrate a simple approach to achieve this. Hydrostatic pressure can significantly enhance Jc in NaFe0.97Co0.03As single crystals by at least tenfold at low field and more than a hundredfold at high fields. Significant enhancement in the in-field performance of NaFe0.97Co0.03As single crystal in terms of pinning force density (Fp) is found at high pressures. At high fields, the Fp is over 20 and 80 times higher than under ambient pressure at12 K and 14 K, respectively, at P = 1GPa. We believe that the Co-doped NaFeAs compounds are very exciting and deserve to be more intensively investigated. Finally, it is worthwhile to say that by using hydrostatic pressure, we can achieve more milestones in terms of high Jc values in tapes, wires or films of other Fe-based superconductors.

Giant magnetic flux jumps are observed in magnetic hysteresis loops of Ba0.6K0.4Fe2As2 single crystals. The size of the flux jumps, which appear only at low temperatures (T<4 >K), is so large that it can transform the whole superconducting state into the normal state. The recovery rate to the superconducting state is rather slow, although the superconducting state is almost fully recovered. We show that theoretical predictions based on the adiabatic approach with nonlocal electrodynamics give a good explanation of the flux jumps observed in the single crystals of Ba0.6K0.4Fe2As2.

The magnetofluctuation conductivity, called excess conductivity, originated from the forming of the superconducting droplet near to the mean-field transition temperature, was measured for the optimally doped BaFe1.8Co0.2As2 single crystals with a critical temperature, Tc, of 24.6 K. This measurement of the excess conductivity for magnetic fields up to 9 T was compared with the thermodynamic scaling theory in the critical region, in which not only the Gaussian fluctuation but also fourth order terms of the order parameter are included. An analysis of the excess conductivity showed that the superconductivity followed three-dimensional scaling rather than two-dimensional scaling even though the sample had a layered structure.

We present reversible magnetization measurements for applied fields in the range from 0.5 to 7 T made while varying the temperature for optimally doped BaFe1.8Co0.2As2 single crystals with Tc = 23.6 K. The rounding fluctuating magnetization was observed in the reversible range of magnetization for temperatures above 18 K. This fluctuation effect is quite small compared with that in high temperature cuprate superconductors, but is still large enough for obtaining the essence of the physical properties in this iron pnictide superconductor. This reversible magnetic fluctuation follows a three-dimensional scaling form in the critical fluctuation region for fields above 0.5 T, which indicates that this iron pnictide superconductor belongs to the class of three-dimensional superconductors.

A modification, designated bi-flotation, is described of a combined normal and reverse flotation process for the removal of aluminosilicate gangue from a difficult-to-float diasporic bauxite of low to medium grade that has complex dissemination and fine grain size. Because of the hardness difference between diaspore and the main gangue silicate minerals, a staged grinding route can be adopted. Selective grinding tests showed that the alumina:silica (A:S) ratio is differentiated by grinding time and size fraction. Following an initial low-intensity grinding and classification, the fine fraction (lower A:S) enters normal flotation and the coarse fraction (higher A:S) is treated by reverse flotation after two-stage selective grinding. The choice of classification limit is important. The raw ore has an alumina:silica ratio of 4.19 and the concentrate 9.37; recovery of alumina is 80.18%., A modification, designated bi-flotation, is described of a combined normal and reverse flotation process for the removal of aluminosilicate gangue from a difficult-to-float diasporic bauxite of low to medium grade that has complex dissemination and fine grain size. Because of the hardness difference between diaspore and the main gangue silicate minerals, a staged grinding route can be adopted. Selective grinding tests showed that the alumina:silica (A:S) ratio is differentiated by grinding time and size fraction. Following an initial low-intensity grinding and classification, the fine fraction (lower A:S) enters normal flotation and the coarse fraction (higher A:S) is treated by reverse flotation after two-stage selective grinding. The choice of classification limit is important. The raw ore has an alumina:silica ratio of 4.19 and the concentrate 9.37; recovery of alumina is 80.18%.

Large differences in future climatic scenarios found when different global circulation models (GCMs) are employed have been extensively discussed in the scientific literature. However, differences in hydrological responses to the climatic scenarios resulting from the use of different hydrological models have received much less attention. Therefore, comparing and quantifying such differences are of particular importance for the water resources management of a catchment, a region, a continent, or even the globe. This study investigates potential impacts of human-induced climate change on the water availability in the Dongjiang basin, South China, using six monthly water balance models, namely the Thornthwaite–Mather (TM), Vrije Universitet Brussel (VUB), Xinanjiang (XAJ), Guo (GM), WatBal (WM), and Schaake (SM) models. The study utilizes 29-year long records of monthly streamflow and climate in the Dongjiang basin. The capability of the six models in simulating the present climate water balance components is first evaluated and the results of the models in simulating the impact of the postulated climate change are then analyzed and compared. The results of analysis reveal that (1) all six conceptual models have similar capabilities in reproducing historical water balance components; (2) greater differences in the model results occur when the models are used to simulate the hydrological impact of the postulated climate changes; and (3) a model without a threshold in soil moisture simulation results in greater changes in model-predicted soil moisture with respect to alternative climates than the models with a threshold soil moisture. The study provides insights into the plausible changes in basin hydrology due to climate change, that is, it shows that there can be significant implications for the investigation of response strategies for water supply and flood control due to climate change.

Objective: To establish a ICP-MS method for the determination of heavy metals, including As, Hg, Ib, Cd, in four traditional Chinese medicines. Method: The samples were digested by closed-versel microwave. The four heavy metals were directly analyzed by ICP-MS. Select internal standard element In for the method by which the analyse signal drife is corrected by the signal of another element (internal standard elements) added to both the standard solution and sample. Result: For all of the analyzed heavy metals, the correlative coefficient of the calibration curves was over 0.999 2. The recovery rates of the procedure were 97.5%-108.0%, and its RSD was lower than 11.6%. Conclusion: This method was convenient, quick-acquired, accurate and highly sensitive. The method can be used for the quality control of trace elements in traditional Chinese medicines and for the contents determination of traditional Chinese medicines from different habitats and species.

The unusual zero-magnetization ferromagnet (Sm1−xGdx)Al2 (SGA) with x=0.01 and 0.02 is investigated by magnetic, and magnetotransport and calorimetric measurements. Striking features observed around the compensation temperature Tcomp are an exchange bias in a single-magnetic-lattice compound such as SGA attributable to the anisotropy of the coupling between the spin and orbital moments; an anomalous Hall effect due to the asymmetric magnetic scattering of the conduction electrons; and a field-induced specific heat transition at Tcomp ascribable to the field-induced switching of the spin and orbital moments in a polarized conduction electron sea. The observations reveal the richness of physics in the SGA compound system.