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A periodic open-cell AlSi10Mg alloy with a porosity of 54% was prepared using selective laser melting (SLM), and the microstructure, mechanical properties and deformation behaviour during compression were studied. The eutectic Si precipitated in the network. The average surface roughness along the building direction was 8.96 µm and along the vertical building direction was 4.22 µm. This finding could be attributed to the fact that there were more unmelted particles attached to the building direction than to the vertical building direction. The open cell AlSi10Mg alloy designed in this study has typical elastoplastic deformation, collapse and densification stages during the compression deformation process; however, its joints have not fractured during the compression deformation process due to the high compressive strength. All of the pillars connected at the joint fractured after compression, ductile fracture occurred. [ABSTRACT FROM AUTHOR]

The aims of this study were to investigate the viral differences among lamivudine-resistant hepatitis B virus (HBV) genotypes B and C in vivo. Fifty-three patients carrying lamivudine-resistant HBV were enrolled in this study. HBV genotypes, Levels of alanine aminotransferase (ALT), HBV DNA levels were monitored during therapy. The polymerase and precore/core promoter genes were amplified by polymerase chain reaction and their products were sequenced directly. Among 53 patients resistant HBV genotypes B and C accounted for 41.50% and 58.50%, respectively. The occurrence of reverse transcriptase rt204I mutants was lower in genotype B (36.36%) than that in genotype C (87.10%), whereas rt204V mutants was higher in genotype B (63.64%) than that in genotype C (12.90%). The occurrence of precore mutation (nt1896A) was higher in genotype B (77.27%) than that in genotype C (32.26%). Serum HBV DNA levels after emergence of lamivudine resistance were higher in genotype C (7.71 ± 0.80 Log copies/mL) compared with genotype B (6.97 ± 0.77 Log copies/mL). Multivariate analysis identified pretreatment HBV DNA levels, HBeAg status and HBV genotype as independent factors associated with a shorter time to lamivudine resistance( P = 0.035, P = 0.006 and P = 0.001, respectively). Multivariate analysis showed that HBV genotype ( P = 0.004) and pretreatment ALT levels ( P = 0.01) was independently associated with YMDD mutational patterns. The results showed that the YMDD mutational patterns, precore mutation and serum HBV DNA levels differ between lamivudine-resistant HBV genotypes B and C in vivo. It is valuable for treatment of lamivudine-resistant HBV in clinic. [ABSTRACT FROM AUTHOR]

Ti/TiBCN composite coatings were deposited on Ti6Al4V alloy using laser cladding technology. The comprehensive effects of laser specific energy on the microstructure, hardness, corrosion resistance and wear resistance of the Ti/TiBCN composite laser clad coatings were investigated. The phase characteristics of the coatings mainly comprise of Ti, Ti/TiBCN, TiC, Ti3Al, TiN and TiB2. The microstructure of coatings consists of coarse and fine dendritic crystals structure which is centrally symmetric structure with rod-like shape. The Ti/TiBCN composite coating cladding materials can be formed into homogeneous coatings at the laser specific energy of 330 J/mm². The metallurgical pores can be minimized but cannot be completely avoided by adjusting the scanning speed. The highest microhardness of the Ti/TiBCN composite laser clad coating was 1250 HV0.2, which was 3.6 times higher than the Ti6Al4V substrate. Meanwhile, the corrosion resistance and wear resistance of the Ti/TiBCN composite laser clad coating is much superior to that of the Ti6Al4V substrate, where the wear mechanism of coating was abrasive. [ABSTRACT FROM AUTHOR]

AlSi10Mg porous alloy was prepared by selective laser melting (SLM) with a Nd:YAG laser beam, and the compression properties were studied using both experiments and the finite element method (FEM). The results illustrate that the porous alloy undergoes elastic deformation, plastic deformation and densification stage. The joints of the porous alloy are preferentially fractured, and the Si content at the bottom position of the dimple is higher than the dimple edge. During the compression process of the porous AlSi10Mg alloy, the stress and strain distribution at the joint are concentrated, resulting in joint fracture. The inherent elasticity, shear stress and forced contact of supporting plates or chips are the causes of these compression stages. The distribution of Si element in the fracture is caused by the dimples that are easily formed at the a-Al/Si interface, eventually resulting in the Si content at the bottom of the dimple being higher than the dimple edge. [ABSTRACT FROM AUTHOR]