Search

The microscopic mechanical characteristics of ultranano-crystalline diamond films which were prepared in four different atmospheres were investigated for the applications in microelectron-mechanical system (MEMS). The loading–unloading curves and the change of modulus and hardness of samples along with depth were achieved through nanoindenter. The results show that the films which are made in atmosphere without Ar have the highest recovery of elasticity, hardness (72.9 GPa) and elastic modulus (693.7 GPa) among the samples. Meanwhile, samples fabricated at a low Ar content have higher hardness and modulus. All the results above demonstrate that atmosphere without Ar or low Ar content leads to better mechanical properties of nanodiamond films that are the candidates for applications in MEMS.

Aim at the multi-faceted nature and universality of the EMC problems in high-speed PCB, based on a three-line coupling model and considering the influence of via holes caused, board-level EMC problems of PCB were researched on point for point. In this paper, the research and simulation were launched by a kind of software named Hyperlynx, and a 6-layer PCB model was built and used. Our Research was focused on the EMC problems existed in hierarchy and layer medium. On the basis of the simulation results, and combined with previous experience in the PCB design, some effective measures for improving EMC in high-speed PCB design were summarized, which could be taken as a clearly reference in design of high-speed PCB.

AA7085 aluminum alloys with different Cu/Mg ratios (0.67, 1.0, 1.06, 1.6) were prepared by ingot metallurgy method. The effects of Cu/Mg ratio on the microstructure, mechanical properties and corrosion behavior of the AA7085 alloys were investigated by optical microscope, scanning electron microscope (SEM), mechanical properties and corrosion testing. The results indicate that a better recrystallization inhibition and corrosion resistance can be achieved when Cu/Mg ratio is 1.6. When Cu/Mg ratio is 0.67, the alloy reveals better mechanical properties, and the tensile strength and yield strength of AA7085 alloys are 586 and 550 MPa, respectively. Moreover, both the mechanical properties and corrosion resistance of the alloy are reduced when Cu/Mg ratio is equal to 1.0.

To investigate the role of cerebral computed tomography (CT) in the evaluation of the severity of brain injury following hypoxia in neonates.A total of 114 full-term newborns who had perinatal hypoxia, including 25 cases of hypoxic-ischemic encephalopathy (HIE), 36 cases of neonatal asphyxia and 53 cases of simple intrauterine fetal distress, were enrolled in this study. Twenty normal newborns served as the Control group. All had cerebral CT scan at 2-7 days of age. Neonatal behavior neurological assessment (NBNA) was performed at 5 days of age.The average NBNA scores were significantly lower and the abnormality rate of NBNA was significantly higher in the HIE group than in the other three groups (P0.05). The Asphyxia and the Distress groups had also lower NBNA scores and higher abnormality rate of NBNA than the Control group (P0.05). Twenty-two patients were found to have cerebral CT abnormality in the HIE group, but there was only 1 case in the Control group (P0.01). The abnormality rate of cerebral CT in the Asphyxia and the Distress groups was not statistically different from that of the Control group. Twenty-five cases of HIE were divided into mild (n=15), medium (n=6) and severe (n=4) by clinical grading but were divided into normal (n=3), mild (n=10), medium (n=7) and severe (n=5) by CT grading. CT and clinical grading on HIE was not consistent. The sensitivity of CT in the diagnosis of mild, moderate and severe HIE was 47%, 33% and 50% respectively, the specificity was 70%, 74% and 86% respectively and the accuracy was 48%, 64% and 80% respectively.CT evaluation on mild brain injury induced by asphyxia or intrauterine fetal distress is not of any value and the role of CT evaluation on the HIE grade is uncertain and doubtful.