圆弧“U”形结构安装座铸造工艺改进

安装座为精铸件,其结构总体呈半圆弧形,一端为“U”形结构,该产品主要工艺难点为圆弧径向及“U”形结构开口端易变形,圆弧径向两端加工后易出现“黑皮”。通过工艺改进运用反变形工艺、工艺拉筋等工艺措施有效解决铸件变形问题,提高产品铸造工艺出品率。     

球形高电压LiNi0.5Mn1.5O4的制备及其电化学性能

以化学共沉淀法制备的球形Ni0.25Mn0.75CO3为前驱体合成高电压正极材料LiNi0.5Mn1.5O4,探讨用前驱体与Li2CO3直接反应和用前驱体分解后的氧化物与Li2CO3反应两种工艺路线对LiNi0.5Mn1.5O4形貌和电化学性能的影响。用扫描电镜(SEM)和X射线衍射(XRD)对Ni0.25Mn0.75CO3前驱体和LiNi0.5Mn1.5O4样品进行表征,用充放电测试和循环伏安法对LiNi0.5Mn1.5O4样品进行电化学性能研究。结果表明:两种方法合成的LiNi0.5Mn1.5O4均具有尖晶石型结构。但以前驱体Ni0.25Mn0.75CO3直接与Li2CO3反应合成的LiNi0.5Mn1.5O4的一次粒子颗粒较大,形貌较差,性能也较差;而以前驱体分解后的氧化物与Li2CO3反应合成的LiNi0.5Mn1.5O4的形貌及性能均较好。在3.0~4.9 V的电压范围内,1C倍率下电池的放电比容量达到136.3 mA.h/g,循环100次仍有126.5 mA.h/g,且材料具有较好的倍率性能;5C倍率下的首次放电比容量高达120.7 mA.h/g。     

Influence of iron doping towards the physicochemical and biological characteristics of hydroxyapatite

Hydroxyapatite (HAP) is the naturally occurring mineral form of calcium apatite and the most studied material as a bone substituent. Considering HAP's inherent properties, this study explored changes in HAP's characteristics from doping with other metals such as Fe. To form pure HAP and Fe-HAP with different amounts of Fe, we used the hydrothermal approach, and the composites that formed were thoroughly analyzed for their crystallinity, surface bonding, morphology, magnetic behavior, mechanical strength, biocompatibility, hemocompatibility, and in vitro cytotoxicity. The powder XRD studies confirmed the samples' crystallinity, and the lowest crystalline size was 19.7 nm in 10Fe-HAP. The FTIR analysis confirmed the formation of HAP by the hydroxyl, phosphate, and carbonate groups. The FESEM demonstrated that the morphology of the pure HAP was rod-shaped, which transformed into spheres after Fe doping. The EDS analysis confirmed the successful formation of HAP and Fe-HAP composites. The magnetic studies indicated the diamagnetic behavior of the pure HAP, while the Fe-doped HAPs had a superparamagnetic nature with saturation magnetizations (M_s) of 2Fe-HAP, 4Fe-HAP, and 10Fe-HAP at 0.0062, 0.0092, and 0.029 emu/g respectively. Assessment of the mechanical properties, biocompatibility, hemocompatibility, and cytotoxicity indicated that the Fe-doped HAPs were superior to the pure HAP, and among the Fe-HAPs, the 10Fe-HAP) had the highest amount of Fe and the best characteristics. The studies also indicated that Ca²⁺ interactions influenced the cells via HAP doping with that of Fe, equally increasing the physicochemical and biological properties.     

可注射CS/PLLA-SA复合水凝胶的制备及载药性

采用先核后臂法以及丁二酸酐(SA)羧基化修饰合成了末端为羧基的四臂星型聚乳酸(PLLA-SA),将其加入丙酮中得到PLLA-SA纳米分散液.壳聚糖(CS)与分散液通过静电作用自组装形成可注射CS/PLLA-SA复合水凝胶,采用Zeta电位及激光粒度仪、FTIR和SEM等对PLLA-SA、分散液及水凝胶的组成、结构和性能...     

4'-氯-2-氨基联苯的绿色合成与表征

以对氯溴苯和邻氯硝基苯为原料,经格氏反应、Suzuki偶联、Pd-C催化加氢还原3步反应合成了4'-氯-2-氨基联苯.格氏反应中,优化的反应条件为n(对氯溴苯)∶n(硼酸三甲酯)=1.0∶1.2,反应温度为0℃.Suzuki偶联反应中,优化的反应条件为n(邻氯硝基苯)∶n(4-氯苯硼酸)∶n(PdCl2(PPh3)2)...     

磁性金属有机框架材料制备及吸附性能研究

利用简单的溶剂热法合成了MIL-101（Fe）/CoFe₂O₄和MIL-101（Fe）/NiFe₂O₄磁性金属有机框架纳米复合材料。通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）、振动磁强计（VSM）、热重分析仪（TGA）和紫外可见分光光度计（UV）等对复合材料的相结构、形貌、磁性能和吸附性能进行了研究。将磁性金属有机框架材料用于吸附污水中罗丹明B（RhB）,研究了罗丹明B初始质量浓度对复合材料吸附能力的影响。结果表明,制备的磁性金属有机框架复合材料的形貌均匀、结晶度高,具有高的饱和磁化强度。复合物具有金属有机框架材料和磁性材料的双重优点。MIL-101（Fe）/CoFe₂O₄对罗丹明B有较高的吸附能力（97.3 mg/g）。热力学研究发现吸附等温方程符合Langmuir模型,吸附动力学研究表明吸附机制与吸附质和吸附剂有关。磁性金属有机框架纳米复合材料作为污水处理剂将具有广阔的应用前景。     

微生物合成植物天然产物的细胞工厂设计与构建

植物天然产物结构多样,具有丰富的生理活性与功能。利用微生物细胞工厂生产来源稀缺、获取难度大的植物天然产物具有经济可行、环境友好等优势。本文系统介绍了萜烯、黄酮以及生物碱的生物合成途径及其关键酶,阐述了差异转录组学、同功酶挖掘等途径解析与重构的方法。指出关键酶改造、途径动态调控、代谢区室化与代谢网络再平衡是增大外源途径代谢通量、抑制副产物合成、降低产物毒性与菌株代谢负担、提高目标产物合成能力的有效策略。提出了解析合成植物天然产物关键酶在微生物中的催化特异性机制、开发外源途径的高效组装方法等进一步提高微生物细胞工厂生产效率的建议。     

生物质热解利用中主要催化剂的研究进展

催化热解目前逐渐成为生物质转化利用技术的主要研究方向,相比常规热解,催化热解可以对生物油进行有效提质并且定向产生高值化产品。本文通过对近年来新兴的催化剂进行综述,包括分子筛类催化剂（ZSM-5、HZSM-5、USY等）、炭基催化剂、金属氧化物、白云石、整体式催化剂等,了解了目前生物质热解利用中催化剂领域内的最新研究进展。文中指出,良好的催化剂是保证反应顺利进行的关键,不同催化剂定向产生的高值化产品也有所不同,因此催化剂的正确选择对于生物油的提质起着重大作用。根据目前领域内所研究内容,本文还对各类催化剂的优缺点、产物特性进行了详细比较,并针对该技术现有问题提出了部分建议并进行展望,为以后生物质热解领域催化剂的研究提供了重要的理论依据。     

Optimization of antioxidant peptide production from grass carp sarcoplasmic protein using response surface methodology

The sarcoplasmic protein was extracted from the muscle of grass carp, a Chinese freshwater carp, and was hydrolyzed with five proteases to produce antioxidant peptides. Papain hydrolysate was found to have the greatest activity against lipid peroxidation. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio, time and temperature). The minimum EC₅₀ value (317.25 μg/mL) which signified the maximum antioxidant activity was obtained at an enzyme to substrate ratio of 0.79%, an incubation time of 5.69 h and an incubation temperature of 52.15 °C, which was in agreement with the predicted value (313.99 μg/mL) estimated by RSM within a 95% confidence interval. Also, it was found that moderate denaturation of the sarcoplasmic protein and a modest increase in the degree of hydrolysis promoted the antioxidant activities of the hydrolysates. Oligopeptides (< 3 kDa) contributed more to the antioxidant activity than polypeptides.     

五香兔肉软包装技术的研究

本文以獭兔肉为原料,通过腌制、卤煮后制得的五香兔肉,在不添加任何防腐剂的前提下,通过对包装材料和不同杀菌方式的选择,对软包装后五香兔肉的保存效果进行比较,从而得出一种比较理想的五香兔肉产品软包装方法。