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The mechanical properties and microstructural features of 1561 aluminum alloy weldments processed by single-wire MIG welding and CMT TWIN welding are investigated. The microstructure and mechanical properties of welded joints were studied by nondestructive testing, metallurgical test, scanning electron microscopy test, fatigue and tensile test. It is revealed that the welding efficiency of CMT TWIN welding is more than six times as much as single-wire MIG welding. It can be easy to find weld zone (WZ), fusion line (FL), heat affected zone (HAZ) and base metal (BM) with different characteristics in the metallographic specimen. In weld zone, the particle phase sizes are smaller than that of base material, but the densities of particle phase are increased. The sample fatigue strength of CMT TWIN welding is higher than the singe-wire MIG welding. It is suggested that the CMT TWIN welding has several advantages compared with single-wire MIG welding.

Plasma-MIG hybrid welding and MIG welding of 5083 marine aluminum alloy was carried out. The influences of parameters of welding process on the weldments morphology were investigated in order to optimize the welding process parameters. The macrostructure, microstructure, tensile and bending properties of the optimized joint were studied. The results show that Plasma-MIG hybrid welding not only has a synergistic effect of Plasma and MIG welding but also has a high welding efficiency. Welding speed, Plasma current and MIG current have a significant effect on welding penetration and welding morphology. Meanwhile, the ductility and strength property of weld joint was qualified though the bending test and tensile test. The average tensile strength of weld joint is about 285MPa at room temperature, about 86% of the base metal.

In order to improve the quality of laser cutting of stainless steel porous, the investigation on cutting 0.12mm stainless steel plates was carried out by a50W-powerbridgefiber laser cutting machine.The influence of the auxiliary line angle, laser power, and the pulse width and gas pressure on the cutting quality was studied in this paper.The results show that fewer defects was found on the samples when the cutting angle of auxiliary line was 90°and few splash orburrswas found on the samplesby 40 Wlaser power, with 56 μs pulse width and 1.3MPa gas pressure.

A-TIG welding is a new variant of high-efficiency TIG weld technology, the weld penetration can be improved by using surface activating fluxes. In the present work, 12 mm thick stainless steel plates were welded by A-TIG method utilizing self-developed oxide-based composite activating flux. Results showed that for 12 mm thick stainless steel plates, weld joint of full penetration and one-side welding with back formation and good weld appearance could be achieved by A-TIG welding. Furthermore, compared with traditional TIG welding, the microstructure of A-TIG weld was finer, directivity of dendritic crystals near weld bond line was weaker, and mechanical properties of weld joints was also superior.

The precise design and fabrication of biomaterial scaffolds is necessary to provide a systematic study for bone tissue engineering. Biomaterial scaffolds should have sufficient stiffness and large porosity. These two goals generally contradict since larger porosity results in lower mechanical properties. To seek the microstructure of maximum stiffness with the constraint of volume fraction by topology optimization method, algorithms and programs were built to obtain 2D and 3D optimized microstructure and then they were transferred to CAD models of STL format. Ti scaffolds with 30% volume fraction were fabricated using a selective laser melting (SLM) technology. The architecture and pore shape in the metallic biomaterial scaffolds were relatively precise reproduced and the minimum mean pore size was 231μm. The accurate fabrication of intricate microstructure has verified that the SLM process is suitable for fabrication of metallic biomaterial scaffolds.

Based on the Marshall-Palmer, Weibull raindrop size distribution and Mie electromagnetic scattering model, the relationships of attenuation coefficient of terahertz (THz) atmospheric window waves with precipitation rate and temperature are studied. Furthermore, combined with the loss of electromagnetic wave transmission in free space, the attenuation of THz communication and the transmission of current mobile communication signals through rain are compared and analyzed. The results show that the attenuation coefficient of THz transmission is increased with increasing precipitation rate, the difference of attenuation coefficient at different THz window waves is small, and the maximum difference is about 3 dB. The rain attenuation of THz wave is first decreased and then increased with increasing temperature, but the temperature has little effect on it. The attenuation of THz wave through rain is much larger than that of mobile communication signal.

Composite powder was obtained from nanometer TiO2 combined with honokiol or quercetin. The linking-pattern, UV absorbance and antimicrobial performance were studied in this paper. The results showed that the primary linking-pattern between nano-TiO2 and honokiol or quercetin is mainly in physical adsorption with little in chemical adsorption. The absorbance of the composite powder becomes stronger than the precursor and the range of UV absorbance range to ultraviolet rays extends dextrad. The composite powder is a kind of high grade material for making multi-functional product with its antimicrobial performance and properties of broad-spectrum sunblock.

This paper presents the direct fabrication of 3 mm-sized components applied in some practical fields using a selective laser melting (SLM) machine with fiber laser: a radiator with variable-section thin wall, an optical component with required smooth surface, and a throttle with a complicated cavity. Dimensional precision, geometric defect, and selection of fabrication direction were discussed after the implementing experiments. Experimental results showed that the minimum absolute error in the wall thickness of the radiator was about 20 μm, the roughness of the optical component should be improved by post-processes, and the cavity of the throttle could be successfully fabricated using tiling display. The current study raises several issues during selective laser melting of fine-structured components which need to be solved before expansion of SLM to practical applications.

To discuss the clinical features, treatment and prognosis of patients with AIDS complicated by tuberculosis(TB).The clinical features of 23 patients with AIDS complicated by tuberculosis admitted from 1997 to July 2004 were retrospectively analyzed.Of the 23 patients, most (94.3%) were young or middle-aged, and 11 (47.8%) died within half a year. The main HIV transmission was via sexual contact in 15 (65.2%) patients. Loss of body weight by 5 - 15 kg was present in all patients, cough for over 1 month in 15 (65.2%), and multiple opportunistic infections were complicated in most cases. Out of the 23 cases, 14 (60.9%) showed only pulmonary TB, and 8 (34.8%) showed lymph node TB. In 12 cases with infiltrated pulmonary TB, X-ray showed bilateral infiltration and no cavity formation was found. Slightly positive PPD test was found in 2 (8.7%) cases, and positive acid-fast bacilli was detected in sputum in 1 case (4.4%). The pre-treatment CD(4)(+) cell number in 23 patients was much lower than that in AIDS patients without complicated TB (P0.05). The pre-treatment CD(4)(+) cell number in patients died shortly after diagnosis was much lower than that in survived patients (P0.05). The HIV RNA level in the 23 patients was much higher than that in patients without complication of TB (P0.05). The mortality in patients treated with therapy against both TB and HIV was much lower than that in patients untreated or treated only with anti-TB therapy (P0.05).For patients with AIDS complicated by TB, the high negative rate in PPD test and the atypical chest X-ray manifestations are common. However, lymph node TB is quite common with high mortality. The pre-treatment CD(4)(+) level decreases significantly, and is associated with mortality. The TB bacilli may accelerate HIV virus duplication. It is suggested that the patients be treated with a combination of anti-TB and anti-HIV therapies.

To explore clinical and chest X-ray features of SARS in children to facilitate correct diagnosis.Clinical manifestations and chest X-ray findings in five children suffering from SARS admitted for treatment in the hospital between February and May, 2003 in Shenzhen area were analyzed. The diagnosis was confirmed by epidemiological, clinical, laboratory and radiological examinations. Among the 5 cases, 1 was a boy and the others were girls at the age of 4 to 13 years.Of the 5 SARS children, 3 presented a history of close contact with SARS patients. Fever was the initiative symptom, 4 had a body temperature of over 38 degrees C with the highest being 40 degrees C; fever sustained from 4 to 7 days with an average of 5.6 days. All the 5 cases developed nonproductive cough; on auscultation, both moist and dry rales could be heard in 3 out of the 5 cases. Mean total white count of peripheral blood was (2.96 - 6.9) x 10(9)/L, and was5.0 x 10(9)/L in 4 cases. SARS associated coronavirus specific RNA fragment was found positive by RT-PCR in 1 case; 1 case was positive for both IgM and IgG antibodies to the virus; 1 case was positive for only IgM antibody and another 2 cases were positive for only IgG antibody. IgG and IgM antibodies to Mycoplasma pneumoniae and Chlamydia pneumoniae as well as blood culture for bacteria were all negative. Findings on chest X-ray examination: 4 cases showed presence of patchy or macular opacities with cord-like shadows in unilateral lung plates while 1 case each showed ground-glass-like opacity and migratory changes; 1 case showed interstitial changes in the lungs in the form of irregular reticular lattice and cord-like shadows. Two cases received CT scanning and macular-patchy or spotty shadows were seen all over the lung. The shortest time for absorption of foci in the lungs was 7 days while the longest was 33 days with a mean of 15 +/- 6 days. None of the cases had any signs of fibrosis in the lungs. All the 5 cases were completely cured and discharged 7 to 40 days (mean 18 +/- 11 days) after admission.Compared with adult cases with SARS, children with SARS had milder symptoms and signs. Presence of unilateral patchy shadow in lungs represented the main chest X-ray findings.