Effects of magnetic annealing on crystallization and magnetic properties of Nd2Fe14B/α-Fe nanocomposite magnets

Crystallization and magnetic properties of Nd2Fe14B/α-Fe nanocomposite magnets have been investigated by annealing the as-spun ribbons with magnetic field.The crystallization process was accelerated by field annealing.The hysteresis loop became to be fat by magnetic annealing at 645 oC for 4 min,which was 690 oC for ribbons annealing without magnetic field.The relative content of α-Fe phase was increased from the results of XRD.The strength of the magnetic field had no obvious influence on the remanence and coercivity,but modified the squareness of hysteresis loop.     

In vitro and in vivo studies on the antioxidant activities of the aqueous extracts of Douchi (a traditional Chinese salt-fermented soybean food)

The aqueous extracts of Douchi were obtained and evaluated for their antioxidant properties. The isoflavones and peptides contents of extracts were determined. Antioxidant activities in vitro of extracts were conducted by determining the α,α-diphenyl-β-pricrylhydrazyl (DPPH) and 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, and the chelating ability of ferrous ions, of which IC₅₀ values were found to be 0.658, 0.204 and 206 mg/mL, respectively. Antioxidant enzymatic activities of extracts in cholesterol-fed rats and an index of lipid peroxidation (thiobarbituric acid reactive substances (TBARS)) were determined, and hepatic tissue ultramicrostructure was also observed under transmission electron microscope (TEM). These results showed that, in Douchi extracts groups, superoxide dismutase (SOD) activities in liver and kidney, catalase (CAT) activity in liver, and glutathione peroxidase (GSH-Px) activity in kidney increased significantly compared with the negative control group (p < 0.05). TBARS in liver and kidney of extracts groups decreased significantly (p < 0.05). Less fatty degeneration in hepatocytes of extracts groups was found on TEM photos. The percentage of total isoflavones and peptides contents in aqueous extracts were 0.087% and 40.7%, respectively. These results showed that Douchi extracts had excellent antioxidant activities, might affect the activities of antioxidant enzymes and lipid peroxidation, and mitigate the lipidosis of hepatocytes.     

α-Glucosidase inhibitory effect by the flower buds of Tussilago farfara L.

Methanolic extracts from the medicinal parts of 50 traditional Chinese herbs were tested in screening experiments for rat intestinal α-glucosidase. The methanolic extract from flower buds of Tussilago farfara L. (Compositae) showed the highest maltase inhibitory activity, with maltose as a substrate. Enzyme assay-guided fractionation of this extract afforded 3,4-dicaffeoylquinic acid (1), 3,5-dicaffeoylquinic acid (2), 4,5-dicaffeoylquinic acid (3) and rutin (4), and the structures of these compounds were elucidated on the basis of MS and NMR data analyses. Compounds 1, 2 and 3 showed comparative maltase inhibitory activities, and the IC₅₀ values were 0.91 mM, 0.90 mM and 0.89 mM, respectively. Comparison of the activities of 1–3, chlorogenic acid (5), quinic acid (6) and caffeic acid (7) suggested that the number of caffeoyl groups attached to a quinic acid core were important for the potency. Rutin (4) showed moderate activity and inhibited 41% of maltase activity at a concentration of 1 mM. This is the first report on mammalian α-glucosidase inhibition of T. farfara and the isolation of 1, 2 and 3 from this herb species. These results suggest a use of the extract of T. farfara for antidiabetes.     

影响SnO2纳米晶体修饰的α-Al2O3微滤膜流动电势的因素

试验研究了不同电解质溶液pH值以及其离子浓度和种类对SnO2纳米晶体修饰的α-A120,微滤膜流动电势的影响规律,结果表明,对于Nacl溶液,膜流动电势随溶液浓度的增大而降低,其等电点在4．6左右;随着溶液的pH值由3增加到10,膜流动电势由正值逐渐变为负值,而对于FeSO4,CaSO4,Na2SO4,NaCl和CaCl2溶液,当溶液的浓度固定时,膜流动电势随溶液电导率的增加而降低。     

纳米Al2O3的晶型对聚酰亚胺杂化薄膜性能的影响

将经偶联剂处理的纳米Al2O3粉体,借助超声波以一定方式均匀分散于聚酰胺酸溶液中,制备出Al2O3不同晶型、不同含量的PI/纳米Al2O3杂化薄膜,并对杂化薄膜微观形貌、聚集态结构、光透过率、热稳定性、电击穿场强进行研究,分析Al2O3晶型和含量对PI/纳米Al2O3杂化薄膜的结构和性能的影响.结果表明:PI/纳米Al2O3杂化薄膜的热稳定性,电击穿场强均高于纯PI薄膜,且随着纳米Al2O3含量的提高热稳定性也随之提高,电击穿场强先升高后降低;填充Al2O3粉体的晶型对PI薄膜分子链堆积密度有较大的影响,导致添加不同晶型Al2O3的杂化薄膜性能的差异.     

α-Ni(OH)2/SiO2核壳以及α-Ni(OH)2空心微球的制备及表征

采用以正硅酸乙酯(TEOS)水解为基础的硅溶胶种子生长法制备了粒径约为270nm的近单分散二氧化硅球型颗粒.采用一种新的溶液生长法,以氢氟酸作为溶液中镍离子配位剂,加入氨水调节溶液pH值的同时作为镍离子补充配位剂,60℃水浴条件下在已制得SiO2微球表面均匀包覆α-Ni(OH)₂得到Ni(OH)₂/SiO₂核壳结构,Ni(OH)₂壳层厚度约为35nm.结合多步包覆法提高Ni(OH)₂壳层厚度,三次包覆后壳层厚度达到约100nm,四次包覆后约为140nm.采用20wt％的强碱NaOH溶液对三次包覆后的Ni(OH)₂/SiO₂核壳结构进行处理,得到了壳层厚度约为95nm的α-Ni(OH)₂空心微球.空心微球具有较大的比表面积为141.06m²/g.     

基于蕴涵算子族的模糊推理的FMP三I约束算法

提出了基于蕴涵算子族L-λ-R₀的模糊推理的思想,这将有助于提高推理结果的可靠性。针对蕴涵算子族L-λ-R₀给出了模糊推理的FMP模型的α-三I约束算法、三I约束算法,并说明其现实意义。     

Dy-黄长石固溶体的氧化行为研究

本 工 作 选 取 了 四 个 Dy-黄 长 石 固 溶 体 Dy₂Si_3-xAl_xO_3+xN_4-x(Dy-M’, x=0, 0.3, 0.6 和 1.0) 组 份, 试 样 由 热 压 工 艺 制 成, 并 置 于 马 弗 炉 中 于 1000℃ 氧 化 20 h. 随 着 固 溶 度 x 的 增 加, 氧 化 增 重 的 行 为呈 现 出：Dy-M’(x=0.6)<< Dy-M’(x=0.3)α-Sialon 的试 样,经 热 压 制 备,分 别 在 1000℃和 1300℃ 氧 化 20 h. 在第 一 种 条 件 下,没 有 发 现 明 显 的 氧 化 增 重, 显 微 结 构 观 察 表 明 样 品 未 出 现 开 裂. 而 在 1300℃ 氧 化 20 h 时, Dy-α’-M’氧 化 表 面 层 是 含 Si0_2 和 α-Dy₂Si₂O₇ 晶 粒 的 硅 酸 盐 层, 其 中 α-Dy₂Si₂O₇ 晶 粒 在 氧 化 表 面 具 有 择 优 取 向.     

一株α-淀粉酶产生菌的分离、鉴定及产酶条件研究

为获得具有高产α-淀粉酶能力的菌株,从不同土壤环境中分离产酶菌株,对其进行分类鉴定和产酶条件研究。通过透明圈法初筛、3,5-二硝基水杨酸(3,5-dinitrosalicylic acid,DNS)法复筛分离得到产α-淀粉酶能力较强的菌株,利用形态学和生理生化反应特征,结合16S rDNA序列分析,对其进行分类鉴定;通过单因素试验和正交试验确定该菌株的最佳产酶条件。结果表明:从土壤环境中分离得到一株产α-淀粉酶菌株MF04,初步鉴定为蜡状芽胞杆菌(Bacillus cereus),其初始产酶活力为32.5 U/mL;产酶条件试验结果显示其最适培养温度为37℃,初始pH值为6.0,培养时间为72 h,经优化后液体发酵得到的粗酶液酶活力为60.2 U/mL,是优化前的85.2%。因此分离得到菌株MF04在工业生产中具备潜在开发价值。