中华绒螯蟹对常用饲料原料氨基酸的消化率

用Cr2O3间接测定法测定了中华绒螫蟹对秘鲁鱼粉、国产鱼粉、豆粕、麦麸、四号粉、虾肉壳粉、啤酒酵母粉等7种常用饲料中蛋白质和氨基酸的表现消化率．结果表明，中华绒螫蟹对这7种原料的蛋白质消化率分别为：90．45％、89．41％、8525％、69．05％、78．45％、89．65％和83．95％；总的氨基酸消化率为：91.83％、92．23％、86．33％、79，29％、79．86％、91．29％和84．99％．动物性原料的消化率均高于植物性原料．经分析，蛋白质和氨基酸的消化率与原料中的粗纤维含量呈负直线相关关系（rp＝－0．6672P＜0．1，rA=－0．8763，P＜0．01）．     

Bridgman growth of LiYF_4 single crystal in nonvacuum atmosphere

Using LiF and YF3 as starting materials,we prepare feed material from fluorides according to the molar ratio of LiF:YF3=51.5:48.5.The anhydrous LiYF4 polycrystalline material is synthesized via the fluoridation process with a dried HF flow at elevated temperature.By charging the feed material and adding a small amount of active carbon powder in a sealed platinum crucible,the crystal can be grown via the vertical Bridgman method in a nonvacuum atmosphere.This is possible because the oxidization and volatilization of the melt is avoided.Using optimum conditions,that is,a growth rate of 0.5-0.6 mm/h and a temperature gradient of 25-30℃/cm across the solid-liquid interface under a furnace temperature of 920-930℃,the colorless crystal LiYF 4 with the size of φ25 × 50 (mm) is successfully grown.The optical transmittance of the crystal is as high as 85% above the absorption edge at 190 nm.The induced absorption bands are observed below 700 nm in the transmission spectrum after the crystal is subjected to a high dose of γ-ray irradiation.     

液相色谱-串联质谱法测定饲料原料中26种霉菌毒素

建立了同时检测玉米、豆粕等饲料原料中脱氧雪腐镰刀菌烯醇等26种霉菌毒素的液相色谱-串联质谱(LC-MS/MS)方法。玉米和豆粕样品经乙腈-水-甲酸(84∶15.9∶0.1,V/V)超声提取1 h,取1 m L上清液经Mycospin 400多功能净化柱净化,浓缩干燥,0.25 m L水-甲醇-甲酸(95∶4.9∶0.1,V/V)复溶,上机测定。采用反相C18色谱柱分离,以0.1%甲酸-水和0.1%甲酸-甲醇溶液作为流动相进行梯度洗脱,采用多反应监测离子模式进行定性分析。基质效应考察发现,样品提取液经Mycospin 400多功能净化柱净化后,大部分毒素仍有较强的基质效应。因此,采用基质匹配标准曲线外标法进行定量分析。在高、中、低3种添加浓度水平下,26种霉菌毒素的平均回收率为61.9%~119.5%,相对标准偏差介于0.8%~18.6%之间。针对不同目标物,本方法的定量限为0.5~25μg/kg。