Weldability evaluation and tensile strength estimation model for aluminum alloy lap joint welding using hybrid system with laser and scanner head

Aluminum welding using a hybrid system with a laser and scanner welding head was performed under various welding conditions to verify the feasibility of applying an aluminum alloy to a car body.The experimental material was 5J32 aluminum alloy,and the laser power,welding speed,and laser incidence angle were used as the control variables.The weld bead shape and the tensile shear strength were evaluated in order to understand the aluminum lap joint weld characteristics.Analysis of variance (ANOVA) was conducted to identify the effect of the process variables on the tensile shear strength.Tensile strength estimation models using three different regression models were also suggested.The input variables were the laser power,welding speed,and laser incidence angle,and the output was the tensile shear strength.Among the models,the second-order polynomial estimation model had the best estimation performance,and the average error rate of this model was 0.058.     

Internal modification in transparent hybrid germanium-silica plates using plasma formation induced by a femtosecond laser

The fabrication of an internal diffraction grating with photoinduced refractive index modification in planar hybrid germanium-silica plates was demonstrated using low-density plasma formation excited by a high-intensity femtosecond (150 fs) Ti:sapphire laser (λp=790 nm).The refractive index modifications with diameters ranging from 400 nm to 3 μm were photoinduced after plasma formation occurred upon irradiation with peak intensities of more than 2×1013 W/cm2.The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred.     

船用5052-O铝合金在海水中的力学和电化学性能(英文)

采用电化学实验和SEM表面形貌观察,对船用5052-O铝合金在海水中的腐蚀保护电位进行优化,以克服诸如点蚀、腐蚀、应力腐蚀开裂和氢脆等行为的发生。在外加电流阴极保护的条件下,最优的保护电位范围为-1.3V～-0.7V。在此电位下,试样的腐蚀电流密度较低,经恒电位实验后,试样表面形貌保持得较好。     

5083-H116铝合金在气蚀条件下的恒电位腐蚀防护技术

研究铝合金5083-H116在海水中的气蚀损伤行为特征,以期提高合金的耐气蚀性能。通过在不同电位条件下进行的恒电位实验,确定抑制气蚀损伤的最优保护电位。实验在电位为-2.2--1.4 V的范围内进行,这对应于铝合金5083-H116阴极极化曲线上的浓差极化和活化极化区域。对实验获得的电流密度-时间曲线进行研究,通过三维显微镜和扫描电子显微镜分析合金表面的损伤情况。结果表明,合金的最优保护电位为-1.9--1.5 V,在此电位条件下,合金的气蚀损伤得到显著地减轻。     

环氧树脂/碳化硅复合材料的热性能及韧性

采用碳化硅作为增强剂制备了环氧树脂/碳化硅复合材料,考察了复合材料的热学及力学性能。实验结果表明,碳化硅的添加使环氧树脂的玻璃化温度提高。当碳化硅添加质量分数为3%时,复合材料的韧性与纯环氧树脂相比提高了35%。     

蜡样芽孢杆菌D-11降解粉末壳聚糖制备水溶性低聚糖的研究

为了省去制备胶状壳聚糖的工艺,能有效降解粉末壳聚糖利用到低聚糖的生产,利用自然环境中筛选得到的产壳聚糖酶菌株蜡样芽孢杆菌D-11,进行了基质条件优化实验。结果表明,以筛孔分别为20、40、60、80目的粉末壳聚糖(3±0.5 cm;脱乙酰度98.1%)为基质,培养液含有1%的吐温60时,降解粉末壳聚糖的能力比对照提高12%,当筛孔60目的粉末壳聚糖为碳源(浓度0.6%)时,降解粉末壳聚糖的能力提高62.5%。随着基质每毫克中酶活性的提高,对粉末壳聚糖的分解率也随之增加。同时利用薄层色谱法分析低聚糖的分布,有效证明了该D-11菌株具有降解粉末壳聚糖的能力,且发现壳聚糖酶对基质粉末状态的降解率有选择性。     

发酵糙米乙醇提取物改善3T3-L1脂肪细胞糖脂代谢

探讨发酵糙米乙醇提取物(FBREE)对胰岛素抵抗3T3-L1脂肪细胞糖脂代谢的影响。高浓度葡萄糖加胰岛素刺激诱导3T3-L1脂肪细胞胰岛素抵抗模型。不同浓度FBREE处理细胞24 h后检测培养液中葡萄糖,游离脂肪酸(FFA),甘油,甘油三酯(TG),肿瘤坏死因子(TNF-α)和白介素6(IL-6)水平。实时定量PCR检测细胞氧化物酶体增殖激活受体γ(PPARγ),CAATT增强子结合蛋白(C/EBPα),固醇调节元件结合蛋白(SREBP1c),葡萄糖转运蛋白4(GLUT4),脂肪酸结合蛋白(a P2),蛋白酪氨酸磷酸酶1B(PTP1B),葡萄糖转运蛋白(GLUT-4),激素敏感脂肪酶(HSL)和TNF-α,IL-6,单核细胞趋化蛋白-1(MCP-1)和C反应蛋白(CRP)的m RNA表达。FBREE具有促进细胞葡萄糖利用,降低细胞内TG含量,减少FFA及甘油溢出的能力。与模型组细胞相比,高浓度FBREE(100μg/m L)处理的细胞中TG和FFA水平分别下降52.44%和37.83%。FBREE同时能减少模型细胞TNF-α和IL-6的分泌,高浓度FBREE(100μg/m L)分别抑制TNF-α(21.18%),IL-6(31.39%),MCP-1(40.09%)和CRP(41.73%) mRNA表达。此外,FBREE有效降低细胞中PPARγ,C/EBPα,SREBP1c,PTP1B,a P2和HSL的m RNA表达,上调GLUT-4m RNA表达。结果提示,FBREE能有效促3T3-L1脂肪细胞消耗葡萄糖,分解TG,减少FFA和甘油溢出;调控细胞糖、脂代谢来改善胰岛素抵抗,并降低胰岛素抵抗所致炎症水平的升高。     

PURIFICATION OF CELLULASE FROM FUSARIUM MONILIFORME AND ITS APPLICATION TO THE PRODUCTION OF RED BEAN STARCH PRECIPITATE

To investigate the effect of cellulase on increase of recovery of red bean starch precipitate, cellulases from Fusarium moniliforme were purified and applied to the production of red bean starch precipitate. Oneã-glucosidase, two filter paper degradation enzymes (FPase), one endo-ã-glucanase (endo-Cx) and one exo-ã-glucanase (exo-Cx) were purified by ammonium sulfate fractionation, gel filtration and ion-exchange chromatography. Optimum temperature and time of submersion of red beans for reduction of hardness was 50°C and 2 h. Maximum sedimentation rate of starch was obtained when the red bean was incubated in a mixture of 0.004 units/mL of FPase and 0.3 units/mL of CMCase, and maximum recovery of red bean starch precipitate was obtained with 0.004 units/mL of FPase and 0.2 units/mL of CMCase. Enzyme treatment reduced suspended solids about 40% in waste water compared with control. A little hydrolysis in cell wall, intercellular space and interstarch granular space was observed.     

Scanning Calorimetric Behavior of Tilapia Myosin and Actin due to Processing of Muscle and Protein Purification

The thermal behavior of tilapia muscle proteins was investigated by differential scanning calorimetry at various stages in the processing of surimi and during purification of myosin and actin. A shift in the thermal transition of actin to lower temperature was observed and the enthalpies of denaturation for both actin and myosin decreased with further processing. Salt addition also induced shifts in denaturation transitions to lower temperatures and decreased enthalpies of denaturation.     

Differential Scanning Calorimetry of Fish Muscle: The Effect of Processing and Species Variation

Differential Scanning Calorimetry (DSC) has been used to study the thermal properties of fish muscle proteins and to measure the extent of their denaturation under various processing conditions. Fish myosin was susceptible to denaturation by frozen storage and dehydration. Denaturation of certain fish proteins was partially reversible. Although fish myosin was very unstable, its thermal stability was found to increase in species adapted, to higher environmental temperatures.