提高奶牛细管冻精精子活力的试验研究

为了提高奶牛细管冻精精子的活力,试验探索了稀释液种类、最佳熏蒸距离、最佳冷冻温度、最佳熏蒸时间、不同解冻温度及时间对精子活力的影响。结果表明:精子在由柠檬酸钠和果糖组成的稀释液中存活时间长,在三羟甲基氨基甲烷稀释液中冷冻后精子活力高于其他稀释液;牛细管冻精最佳熏蒸距离为2.5 cm,时间影响不显著(5～10 min均可);用50℃温水解冻15 s的精子活力比其他解冻温度和时间时的精子活力要好。     

木纤维/PLA复合材料非等温结晶过程研究

使用DSC对纯聚乳酸（PLA）、木纤维（WF）/PLA复合材料的熔融和非等温结晶过程进行测定和分析。结果显示木纤维的加入一定程度上会在影响PLA的结晶性能,能够促进PLA的异相成核从而提高其结晶度,但晶核密度的增加会减小晶核之间的空间从而阻碍结晶生长,并且降低结晶的生长速率。本研究还分别采用Avrami方程和莫志深方法对实验结果进行分析,结果表明在非等温结晶过程中,降温速率对PLA结晶性能的影响比较显著。降温速率越快,材料的结晶温度越低,形成结晶的形态也越不一致,结晶度也越低。     

水牛发情周期生殖激素变化规律及唾液结晶的分析

试验对水牛发情周期血清和唾液中雌二醇(E_2)和孕酮(P_4)的浓度变化规律、水牛唾液结晶与卵泡发育变化分别进行了分析研究,为进一步探讨水牛发情规律、指导生产提供依据。采用酶联免疫分析法(ELISA)测定发情母水牛血清和唾液中E_2和P_4的浓度变化,并对血清和唾液的激素变化规律进行相关性分析。结果表明,水牛血清和唾液中的E_2和P_4呈波动性变化。发情前期,唾液中P_4浓度一直维持在6.50～7.10 ng/mL,发情第13天达到11.09 ng/mL,随后快速下降。唾液中E_2浓度在发情第3～5天出现一个峰值178.53 pg/mL,在第14～17天唾液中E_2浓度显著升高,出现第二个峰值179.10 pg/mL。母水牛唾液中E_2和P_4浓度的变化趋势与其在血清中的变化趋势基本一致,均呈显著相关(P<0.05);唾液中E_2与P_4浓度呈极显著相关(P<0.01)。水牛发情当天唾液结晶呈现明显的蕨类作物形状且分维值显著低于其他时间点(P<0.05)。水牛发情周期唾液结晶图形的变化与卵巢卵泡发育基本同步,可作为监测水牛发情及预测排卵的可靠指标之一。     

Ni—Si—B系非晶合金的结晶度与退火温度关系的研究

本文对Ｎｉ＿（８５－ｘ）Ｓｉ＿（１５）Ｂ＿ｘ（ｘ＝１３，１７，２１）系非晶合金条带的晶化（经过处理后的）结晶度的测定进行了比较系统的研究．结晶度的测定系采用电子计算机分峰方法将ｘ射线衍射曲线中的非晶峰与结晶分离开来，其中非晶峰以三次多项式表示，结晶峰以高斯－柯西复函数表示，由这些表达式组成联立方程组，用最小二乘法求解，并计算出它们的相对强度值，得到其结晶庆与退火温度呈抛物线关系曲线．     

高含量大豆皂苷的制备工艺研究

为了得到高含量大豆皂苷，该文对6种大孔吸附树脂即AB-8，XAD-2，HPD-100，ADS-7，HPD-300，HPD-600进行优选，以上样量、洗脱率和产品纯度为指标，用柱层析法对低含量的大豆皂苷提取液进行初步分离，得到大豆皂苷粗品。然后通过结晶进一步提高其纯度。考察并优化了结晶时的溶剂、大豆皂苷的初始浓度、降温速率等工艺条件。结果表明：ADS-7树脂为合适的吸附剂；优化的柱层析条件为：上样和洗脱温度60℃，上样原料浓度6 mg/mL，上样和洗脱流量均为1.0 BV/h；优化的结晶工艺条件为：结晶溶剂30%～40%乙醇，大豆皂苷初始浓度165 mg/mL，降温速率3.2℃/h。在上述条件下，用柱层析法可使大豆皂苷的含量从原料中的3.0%提高至45%以上，大豆皂苷收率大于90%。再通过结晶可得含量大于96.0%的大豆皂苷，大豆皂苷收率大于50％。说明该文研究的制备工艺明显优于现有的萃取工艺，具有重要的工业应用价值。     

β-谷甾醇和γ-谷维素的结晶行为研究

利用X-射线衍射和扫描电子显微镜分析了β-谷甾醇、γ-谷维素及其混合物的结晶行为,从X-射线衍射分析可以看出快速冷却结晶可以促进β-谷甾醇、γ-谷维素及其混合物形成晶体。通过偏光显微镜观察发现,β-谷甾醇和γ-谷维素的添加量对油脂中的结晶体有明显的影响,且随着混合甾醇的添加量增加,晶体形成的尺寸也呈现增大的趋势,当混合甾醇的添加量为1%~3%时,晶体的形状呈现出细长的管状结晶,当添加量增大到3%以上时,晶体的结构呈现出互相交错的四瓣形聚集态,形似绣球菊,最终形成结构稳定的油脂凝胶。     

Structure and properties of syndiotactic polystyrene fibers prepared in high-speed melt spinning process

High-speed melt spinning of syndiotactic polystyrene was carried out using high and low molecular weight polymers, HMs-PS and LMs-PS, at the throughput rates of 3 and 6 g/min. The effect of take-up velocity on the structure and properties of as-spun fibers was investigated. Wide angle X-ray diffraction (WAXD) patterns of the as-spun fibers revealed that the orientation-induced crystallization started to occur at the take-up velocities of 2–3 km/min. The crystal modification wasα-form. Birefringence of as-spun fibers showed negative value, and the absolute value of birefringence increased with an increase in the take-up velocity. The cold crystallization temperature analyzed through the differential scanning calorimetry (DSC) decreased with an increase in the take-up velocity in the low speed region, whereas as the melting temperature increased after the on-set of orientation-induced crystallization. It was found that the fiber structure development proceeded from lower take-up velocities when the spinning conditions of higher molecular weight and lower throughput rate were adopted. The highest tensile modulus of 6.5 GPa was obtained for the fibers prepared at the spinning conditions of LMs-PS, 6 g/min and 5 km/min, whereas the highest tensile strength of 160 MPa was obtained for the HMs-PS fibers at the take-up velocity of 2 km/min. Elongation at break of as-spun fibers showed an abrupt increase, which was regarded as the brittle-ductile transition, in the low speed region, and subsequently decreased with an increase in the take-up velocity. There was a universal relation between the thermal and mechanical properties of as-spun fibers and the birefringence of as-spun fibers when the fibers were still amorphous. The orientation-induced crystallization was found to start when the birefringence reached — 0.02. After the starting of the orientation-induced crystallization, thermal and mechanical properties of as-spun fibers with similar level of birefringence varied significantly depending on the processing conditions.     

复合温度对玉米淀粉-油酸包合物热分解和消化性质的影响

分别采用DMSO/H2O法制备高直链玉米淀粉-油酸包合物和HCl/KOH法制备普通玉米淀粉-油酸包合物,研究复合温度对其热分解性质和消化性质的影响.研究结果表明:随复合温度的升高,高直链玉米淀粉-油酸包合物的最快反应速率对应温度升高,相对消化率和预期血糖指数先升高再降低;普通玉米淀粉-油酸包合物的最快反应速率对应温度、相对消化率和预期血糖指数降低.红外图谱表明淀粉与油酸形成了包合物.     

全氟磺酸树脂催化松香树脂酸的异构化反应

研究在95%乙醇中废弃的全氟磺酸树脂膜(简称PFSR)催化松香树脂酸异构化反应,直接结晶分离枞酸的可行性。结果表明,在常压加热反应条件下,PFSR能够较好地催化松香树脂酸的异构化反应;催化剂用量和反应温度对树脂酸异构化反应速度和异构反应平衡溶液中枞酸相对含量有较大的影响;在松香质量为20 g,溶剂体积为20 mL,PFSR用量为松香质量的20%,反应溶液沸腾温度条件下反应5 h,树脂酸异构反应达到平衡,枞酸相对含量高达78%;过滤分离回收催化剂后,将异构松香溶液直接冷却结晶,析出枞酸粗产品,再在95%乙醇中重结晶提纯3次,得到纯度为95%、产率为35%的枞酸。     

Antioxidant properties of polysaccharide from the brown seaweed Sargassum graminifolium (Turn.), and its effects on calcium oxalate crystallization

We investigated the effects of polysaccharides from the brown seaweed Sargassum graminifolium (Turn.) (SGP) on calcium oxalate crystallization, and determined its antioxidant activities. To examine the effects of SGP on calcium oxalate crystallization, we monitored nucleation and aggregation of calcium oxalate monohydrate crystals, using trisodium citrate as a positive control. We assessed antioxidant activities of SGP by determining its reducing power, its ability to scavenge superoxide radicals, and its activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The nucleation inhibition ratio of trisodium citrate and SGP was 58.5 and 69.2%, respectively, and crystal aggregation was inhibited by 71.4 and 76.8%, respectively. Increasing concentrations of SGP resulted in increased scavenging of superoxide anions and DPPH radicals (IC₅₀ = 1.9 and 0.6 mg/mL, respectively). These results suggest that SGP could be a candidate for treating urinary stones because of its ability to inhibit calcium oxalate crystallization and its antioxidant properties.