Advanced Materials Research Vols. 129-131

Abstract: Web-Based Instruction (WBI) has already become a popular option in many higher education institutes, although its efficiency has not been studied. Students will be influenced by many factors while studying through the network. These factors can result in various learning results. The aim of this paper is to discuss the factors affecting the efficiency of WBI by using the method of questionnaire survey. 50 students from the Department of English and 50 students who are not from the Department of English in Anqing Normal College are research subjects. The influencing factors investigated include independent learning capability (ILC), study conditions in college, and students’ family conditions. The investigation results are analyzed and some methods to improve the learning efficiency are proposed.

Abstract: A mathematical model was developed to describe the oscillating amplitude of the plasma arc injected transverse to an external transverse alternating magnetic field. The characteristic of plasma arc under the external transverse alternating magnetic field imposed perpendicular to the plasma current was discussed. The effect of processing parameters, such as flow rate of working gas, arc current, magnetic flux density and the standoff from the nozzle to the workpiece, on the oscillation of plasma arc were also analyzed. The results show that it is feasible to adjust the shape of the plasma arc by the transverse alternating magnetic field, which expands the region of plasma arc thermal treatment upon the workpiece. Furthermore, the oscillating amplitude of plasma arc decreases with decrease of the magnetic flux density. Under the same magnetic flux density, more gas flow rate, more arc current, and less standoff cause the oscillating amplitude to decrease. The researches have provided a deeper understanding of adjusting of plasma arc characteristics.

Abstract: It has become an urgent problem to be solved for the education world to strengthen cultural education, transmit and develop excellent regional culture and enhance cultural quality of middle school students and the new generation. In the traditional Web-based learning environments used for transmitting regional cultures, there is not strong immersion, flexible interaction methods, interests and entertainments. In response, the basics of the cone of experience and constructivism learning theory are analyzed, a virtual learning environment about Yiwu regional culture is designed, and the system model, framework and the realization processes of key parts are stated.

Abstract: The high-solids anaerobic digestion of biological municipal waste (BMW) produces both a valuable fuel production (methane) and an anaerobic digestion residue. Compost technology was chosen to treat with anaerobic digestion residue and the conclusion was. 1) The anaerobic digestion of the bio-waste as a whole worked fine during the stabilization stage, the maximum daily gas production happened on the 125th day, the maximum was 91.86L/d and TS concentration in the digestive juice was14.78%, methane concentration was about 50-55%, HRT was 20 days and the biodegradation rate was 65.28%;2) The temperature of AD residue compost entered the thermophilic phase(55°C) on day 3 of composting, lasted at least 3days, the changes in pH followed the same trend with a rise from 6.18 to 7.26 on the 14th day, he final mass loss was 30.12%, which resulted in the compost quality higher than innocuity criteria.

Abstract: A three-dimensional axisymmetric mathematical model, including the influence of the swirl exiting in the plasma torch, was developed to describe the heat transfer and fluid flow within a combined plasma arc. In this model, a mapping method and a meshing method of variable step-size were adopted to mesh the calculation domain and to improve the computational precision. To overcome the problem issuing from a coexistence of non-transferred arc and transfer arc and a complicated interaction between electric, magnetic, heat flow and fluid flow phenomena in the combined plasma arc, a sequential coupling method and a physical environment approach were introduced into the finite element analysis on the behaviors of combined plasma arc. Furthermore, the characteristics of combined plasma arc such as temperature, velocity, current density and electromagnetic force were studied.

Abstract: In the present study, effect of pre-oxidized (PO) CuO layer in the joining between polyethylene terephalate (PET) and copper (Cu) by using pulsed Nd:YAG laser was investigated. The experimental result for PET/PO Cu (with pre-oxidized layer) and PET/Cu (without pre-oxidized layer) were presented in this paper. The results showed the pre-oxidation surface improved the welding efficiency. The welded area and tensile shear failure load (TSFL) of PET/PO Cu joint were increased when pre-oxidized layer was introduced. This indicates that high heat was absorbed during laser irradiation of PET/PO-Cu joint compare to PET/Cu joint. On the other hand, the fracture surface of PET/PO-Cu showed the presence of Cu and Cu oxide particles in the PET side. While in case of PET/Cu, no occurrence of Cu particles can be observed. The presence of Cu oxide particles and Cu particles were believed may increase PET/PO Cu joint shear force. From the cross-sectional observation of PET/PO Cu joint interface, it was found that an oxide layer in the laser irradiation area was removed and PET seemed to have intimate contact with Cu surface.

Abstract: To further utilize Eucalyptus leaves in biomedicine and put forward new ideas for biomedical manufacturing, the biomedical resources of extractives of Eucalyptus camaldulensis and Eucalyptus urophylla leaves were analyzed by GC/MS. The results showed that: 1) The main constituents of benzene/ethanol extractives in E. camaldulensis leaves were 1-butanol, 4-butoxy- (14.97%), 2-furancarboxaldehyde, 5-(hydroxym ethyl)- (12.16%), 1,2,3-benzenetriol (10.97%), d-allose(8.59%), 1,4,7,10,13,16-hexaoxanonadecane, 18-propyl-(6.82%), 1,1'-biphenyl, 2,4'- dimethyl- (6.21%), 1-benzoxiren-3-ol(5.58%), α-tocopherol-β-d-mannoside(3.77%), benzene, 1-methyl-2-(phenylmethyl)- (3.61%), methyl β-d-galactopyranoside(3.41%), etc. 2) The main constituents of benzene/ethanol extractives in E. urophylla leaves were 1,2,3-benzenetriol(15.22%), 1,4,7,10,13,16-hexaoxanonadecane, 18-propyl-(8.66%), 3,6,9,12-tetraoxatetradecan-1-ol, 14-[4- (1,1,3,3-tetramethylbutyl)phenoxy]-( 5.79%), naphthalene, 1,2,4a,5,8,8a-hexahyd ro-4,7-dimethyl-1 -(1-methylethyl)- (4.93%), 1,2,3-butanetriol(3.61%), ethyl α-d-glucopyranoside(3.29%), 2-furancarboxaldehyde, 5-(hydroxym ethyl)- (3.27%), 4h-1,3,2-dioxaborin, 2-ethyl-4-met hyl-4,6-bis(2-methylpropyl)- (3.19%), vitamin e(2.97%), etc. The results of function analyses suggested that the benzene/ethanol extractives of both E. camaldulensis and E. urophylla leaves were abundant in materials of noble natural biomedicines.

Abstract: Nanometer calcium titanate immobilized on silica gel G (SGCTO) was prepared by the sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Its application in speciation of Cr(III) and Cr(VI) from water was studied. Adsorption and elution were investigated under different conditions. The results showed that the nanometer calcium titanate was immobilized on the silica gel G firmly, becoming a new adsorbent. At normal temperature, two forms of chromium show different adsorption capacities at different pH values, that is, Cr (III) selectively retained at pH 8–14, but Cr(Ⅵ) can’t be adsorbed. Whereas Cr (VI) retained at pH 1, but Cr(Ⅲ) can’t be adsorbed. Hence complete separation of the two forms of chromium is possible. Retained Cr(III) and Cr(VI) were eluted with 1 mol•L−1 HCl and 2 mol•L−1NaOH, respectively. The Cr(III) and Cr(VI) concentration was measured by atomic absorption spectroscopy. The method was successfully applied for the speciation of chromium in environmental water samples.

Abstract: The semi-solid slurry of AZ31 magnesium alloy was manufactured by gas bubbles stirring. The effects of stirring temperature and stirring time on the microstructure of semi-solid slurry were researched. The results indicate that it is feasible to manufacture the slurry with particle-like primary phases. When the stirring temperature is higher, the morphology of the primary a-Mg presents rosette-like morphology and the size of grain is coarse, and the morphology mainly was α- Mg dendrite at lower stirring temperature. Long stirring time could reduce dendrites and liquid phase, and made the non-dendritic grains well spheroidized. But the effects of longer stirring on shape and size of primary particles are not significant. The optimal process parameters for ideal semi-solid slurry manufactured were stired 3min at 645°C.

Abstract: The photocatalytic activity of TiO2/Y photocatalyst was investigated. The experimental results showed that the activity of TiO2/Y photocatalyst prepared by sol-gel method was greatly affected by calcination temperature and the nature of Y-zeolite. Photocatalytic degradation efficiency increased with increasing content of TiO2 on NaY zeolite and reached its maximum rate of 12.4% when TiO2 content was 90%. When TiO2 content was in the range of 50% to 90% , the activity of TiO2/HY was better than pure TiO2. The activity of TiO2/FeY was comparatively low in the TiO2 content range of 50-90%. The enhancement of photocatalytic activity of TiO2 after loading on Y zeolite is not appreciable, indicating that Y type zeolite is not a promising support for TiO2 prepared by sol-gel method.