液液萃取-QuEChERS净化-高效液相色谱-串联质谱法测定饲料添加剂可溶性粉中五氯酚酸钠含量

建立液液萃取-QuEChERS净化-高效液相色谱-串联质谱法测定可溶性粉中五氯酚酸钠含量的新方法。 可溶性粉先用水溶解后加入1moL/L 盐酸1mL调pH至4左右,加入乙醚液液萃取到乙醚层,蒸干乙醚,乙腈复溶,QuEChERS净化管净化后高效液相色谱-串联质谱测定,标准曲线外标法定量。 五氯酚酸钠在0.50~100μg/L质量范围内线性关系良好,相关系数为0.9994,检出限0.5μg/kg,定量限1.0μg/kg,可溶性粉剂中五氯酚酸钠添加量为1.0、5.0、10.0μg/kg时,五氯酚酸钠的平均回收率为80.2%~94.0%,相对标准偏差小于7%。 该方法快速、高效且价格低廉,适用于饲料添加剂可溶性粉中五氯酚酸钠的快速筛查分析测定。     

羧甲基纤维素钠对壤砂土水分运动及水力参数的影响

科学使用羧甲基纤维素钠(CMC)实现保水控盐对于滨海壤砂盐碱土改良具有重要意义,而明晰CMC对滨海壤砂土水分运动规律的影响是科学使用CMC的重要基础。为研究施加CMC滨海壤砂土水分运动规律,本文通过开展一维垂直土柱积水入渗试验,探索不同CMC施量(0、0.1、0.2、0.4、0.6 g?kg-1) 对壤砂土入渗特性、水分分布和土壤水力参数的影响。结果表明,施用CMC土壤的最终累积入渗量增加了4.90％～15.17％、达到预设湿润锋深度的入渗时间增加了61.90%～604.73%;Philip入渗模型参数吸渗率S和Green-Ampt模型参数KsSf均随CMC施量的增加而减少,吸渗率S和平均土壤水扩散率与CMC施量之间的数学关系分别可用二次多项式和指数函数来表示;CMC增强了土壤的持水能力,土壤剖面含水量提高了0.72%～3.74%;CMC通过改变土壤结构影响了土壤水力参数,滞留含水率θr、饱和含水率θs及进气吸力倒数α均与CMC施量呈正相关关系,而与饱和导水率Ks和形状系数n呈反比关系。通过对变异系数CV的分析发现,CMC对饱和导水率Ks和进气吸力倒数α影响表现为中等差异,对滞留含水率θr、饱和含水率θs和形状系数n表现为弱差异。研究结果揭示了CMC对滨海壤砂土减渗保水的内在机理,为滨海盐碱地的改良提供了理论参考。     

火焰原子吸收法测定黄豆酱中钠的不确定度评定

[目的]更科学合理地表示微波消解-空气-乙炔火焰原子吸收法测定食品中钠含量的测量结果。[方法]根据JJF1059．1—2012《测量不确定度评定与表示》规范要求,以火焰原子吸收法测定黄豆酱中钠为例对测量不确定度进行评定。[结果]分析表明,影响测量结果的主要因素依次为试剂空白、标准物质和仪器测量时标准曲线的拟合;消解液的定容以及稀释引入的不确定度次之。用该法测得黄豆酱中钠含量为17627mg/kg,扩展不确定度为1128mg／kg（95％,k=2）。[结论]该评价方法及结果对营养标签中钠的准确标示有一定的指导意义。     

硝酸钠浓度对亚心形扁藻生长及油脂与淀粉含量的影响

[目的]确定硝酸钠浓度对亚心形扁藻生长及油脂和淀粉含量的影响.[方法]以亚心形扁藻作为试验材料,以海洋微藻培养常用的普适性康维方营养液为基础,考察硝酸钠质量浓度为10 mg/L、60 mg/L、110 mg/L、160 mg/L和210 mg/L的培养基对亚心形扁藻生长及油脂和淀粉含量的影响.[结果]当硝酸钠浓度为10 mg/L时,有利于油脂、淀粉的合成,但此时扁藻生长慢,生物量低,使得这些生物组分的总产量低;当硝酸钠质量浓度为60 mg/L时,油脂和淀粉含量较高,并且扁藻生长快,油脂、淀粉的总产量高;继续增加硝酸钠浓度时,扁藻生物量和各组分含量基本不变.[结论]从微藻生物能源角度考虑,60 mg/L的硝酸钠质量浓度是培养亚心形扁藻的优化浓度.     

双乙酸钠在肉鸭日粮中的添饲效果试验

选用1日龄健康樱桃谷肉鸭600只,随机分为3组,每组设4个重复,每个重复50只肉鸭,试验采用单因素完全随机试验设计。A组饲喂基础日粮,B组、C组在基础日粮的基础上分别添加0.2%、0.4%的双乙酸钠。试验结果表明:日粮中添加双乙酸钠对肉鸭日增重、瘦肉率有显著影响(P<0.05);对肉鸭的饲料转化率有极显著影响(P<0.01);对肉鸭的成活率和屠宰率、皮脂率无显著影响(P>0.05)。B组日增重比A组提高了8.65%(P<0.05),比C组提高了5.45%(P>0.05);B组料肉比较A组降低了11.52%(P<0.01),较C组降低了3.29%(P<0.05);B组的成活率与A组、C组间差异不显著(P>0.05);B组每只肉鸭分别比A、C组多盈利1.04元、1.06元。     

室外型中密度纤维板用黑荆树单宁胶粘剂的研制

采用亚硫酸钠和三聚氰胺-尿素-甲醛预缩液对黑荆树单宁胶粘剂进行改性处理,制备具有良好的耐水性能和胶合性能的单宁胶粘剂。通过小试说明该胶粘剂在压制室外型中密度纤维板的可行性。     

The effects of delays between restraint and sampling on some blood parameters in sheep

Twenty three non pregnant, non lactating aged Merino and Border Leicester ewes were subject to four jugular venipunctures one hour apart (times 0, 1, 2 and 3). Four different delay intervals of 12.5, 64.0, 128.0 and 252.9 seconds between catching and sampling (delays 1, 2, 3 and 4) were used on each sheep in a random manner. Estimates were made of packed cell volumes (PCVs), plasma and erythrocyte sodium and potassium concentrations. The mean PCV at time 0 of 35.4 per cent was significantly higher than the levels of 33.1, 31.8 and 32.2 per cent at times 1, 2 and 3 respectively. There was no significant difference between the means at times 1, 2 and 3. The mean plasma potassium concentrations at time 0 of 4.37 mmol/l was significantly higher than the levels of 4.16 and 4.14 mmol/l at times 1 and 3 respectively. Delays had no significant effects on the means of any of the parameters studied. The findings strongly suggest that sheep become excited by initial handling but not by subsequent venipunctures and that a delay between catching and sampling of between 12.5 and 252.9 second has no effect on the blood constituents studied.     

Sodium dichloroacetate improves radiosensitivity of U251 cells

AIM: To study the change of radiosensitivity of U251 cells after treated with sodium dichloroacetate (DCA) and further to explore the possible mechanism.METHODS: The U251 cells were divided into 4 groups: control group, DCA group, X-ray irradiation without DCA pretreatment (IR) group and X-ray irradiation with DCA pretreatment (DIR) group. MTT assay was applied to determine the cell viability. The intracellular reactive oxygen species (ROS) were detected by DHE fluorescence. The expression level of Bcl-2 was assessed by Western blot. The percentage of apoptosis of cells was determined by flow cytometry. RESULTS: No difference between control group and DCA group in cell viability (P>0.05) was observed. However, the cell viability of both IR group and DIR group was markedly reduced compared with control group (P<0.05). Furthermore, the viability of DIR group was significantly decreased compared with IR group (P<0.05). The percentage of ROS positive cells was obviously increased in DIR group compared with IR group (P<0.05). The expression level of Bcl-2 was sharply decreased in DIR group (P<0.05) and the percentage of apoptosis of cells was significantly elevated (P<0.05) in DIR group compared with IR group.CONCLUSION: The better antitumor effect was obtained by improving the radiosensitivity through pretreating the cells with DCA, and the possible mechanism was down-regulation of the Bcl-2 expression by developing the intracellular ROS.     

CTS-g-PAA/SH高吸水性树脂的缓释和保水性能

【研究目的】以壳聚糖(CTS)、丙烯酸(AA)和腐殖酸钠(SH)为原料，在水溶液中通过接枝共聚反应合成壳聚糖接枝聚丙烯酸/腐殖酸钠(CTS-g-PAA/SH)高吸水性树脂；【方法】考察CTS-g-PAA/SH树脂在不同浓度盐溶液中的溶胀行为、反复吸水性能、SH的缓释性能和在土壤中的实际保水效果；【结果】在SH含量为10%时，CTS-g-PAA/SH树脂在蒸馏水和生理盐水中的吸水倍率分别达到183g/g和41g/g；CTS-g-PAA/SH高吸水性树脂具有较好的反复吸水性能；与CTS-g-PAA相比，含有1.0%CTS-g-PAA/SH树脂的沙土，20d后仍然具有6.75%的保水率；SH能与AA发生聚合反应，形成网络结构，当SH含量超过30%时，过量的SH是以物理填充方式存在于高吸水性树脂的交联网络中，且容易释放；【结论】SH能改善CTS-g-PAA的吸水性，CTS-g-PAA/SH高吸水性树脂不仅可降低产品成本，而且还具有缓释腐殖酸的功能。     

Extractability of cellulases in forest litter and soil

Summary Cellulases in forest litter and soil occur in both bound and extractable forms. The proportion of total bound endocellulase activity (not extractable) increases during decomposition, whereas the proportion of bound exocellulase activity remains fairly constant. The proportions of bound enzymes differ among litter types with different chemical compositions. The proportion of bound activity is higher in mineral soil than in litter. We also investigated the effects of anion type (NaCl versus Na₂SO₄), concentration and pH on the extractability of cellulases and protein in two horizons of two forest soils. The extractability of cellulases increases as pH increases from 3.5 to 5.6. Anion type and concentration did not have consistent effects on extractability. However, there was a trend for higher extractability by sulfate than by chloride and with increasing salinity.