糠醛渣的纤维素酶水解及其最优纤维素转化条件

该文对糠醛渣的纤维素酶水解特性进行了研究,探索利用玉米芯制糠醛联产燃料乙醇工业化生产的可行性。分析糠醛渣组分,表明其半纤维素质量分数为3.1%,纤维素为31.6%,说明糠醛生产过程对玉米芯的预处理基本满足高效酶解糖化糠醛渣并转化乙醇的要求;通过纤维素酶用量、温度、pH值、固液比、转速等因素进行条件优化,确定最佳水解条件：每克底物酶用量为6.7FPU,固液质量体积比1︰6,pH5.2,转速80 r/min;在糠醛渣水解体系中加入吐温80,结果表明在酶施用量较低情况下（6.7 FPU/g）,吐温80对提高糠醛渣水解转化率效果更为明显;通过最优化水解条件,使糠醛渣纤维素转化率达到78%,据此初步判定以糠醛渣为原料转化乙醇的工业化生产具有较大潜力。     

Effect of Tillage,Crop Residues of Preceding Wheat Crop and Nitrogen Levels on Biological and Chemical Properties of Soil in the Soybean–Wheat Cropping System

A 2-year field experiment was conducted to study the influence of three planting methods (Happy Seeder, Straw Chopper + Zero Tillage, and Conventional tillage) and four nitrogen rates (control, 75, 100, and 125% of recommended nitrogen) on the chemical and biological properties of soil. The results revealed that after soybean harvest, dehydrogenase activity and population of Bradyrhizobium sp. (LSBR 3) and plant growth promoting rhizobacteria (PGPR) were increased significantly in Happy Seeder sowing and Straw Chopper + Zero Tillage sowing than conventional sowing and population of Bradyrhizobium sp. significantly increased up to the 100% nitrogen level. There was no significant effect of different planting methods on soil chemical properties. Organic carbon and available nitrogen were increased significantly with an increase in the nitrogen level up to 100% nitrogen (N).     

Greenhouse gases emission,soil organic carbon and wheat yield as affected by tillage systems and nitrogen management practices

Agricultural activities are responsible for greenhouse gases (GHGs) emission in the environment. Strategies are required to enhance the soil organic carbon (SOC) and nitrogen (N) sequestration to adapt and mitigate the climate change. We investigated GHGs emission, SOC and N enhancement under conventional tillage (CT) and zero tillage (ZT) with N management in wheat (Triticum aestivum L.). Seasonal carbon dioxide (CO₂) emission and global warming potential (GWP) reduced for ZT treatments over CT without residues and 100% of required N with a blanket split application (CT – R + 100N). The ZT with 5 t ha^?1 maize (Zea mays L.) residues retention and 75% of required N and GreenSeeker^TM (GS)-aided N management (ZT + R + 75N + GS) reduced yield-scaled GHGs emission and increased total organic carbon (C) stock over CT – R + 100N. However, nitrous oxide (N₂O) emission was lower in CT. The GS-based N management saved 26–35 kg N ha^?1 in different tillage systems in both years over blanket application with higher N uptake and associated reduction in N₂O emission. The study recommends that ZT with residues retention and GS-based N management can minimize the GHGs emission and improve the SOC.     

QuEChERS-气相色谱测定辣椒中的8种有机磷农药残留

[目的]建立同时测定辣椒中敌敌畏、乙酰甲胺磷、治螟磷、甲基对硫磷、马拉硫磷、杀螟硫磷、乐果、水胺硫磷8种有机磷农药残留的QuEChERS-气相色谱分析方法。[方法]样品用乙腈进行超声提取,无水硫酸镁盐析后,提取液经N-丙基乙二胺(PSA)、C18和石墨化炭黑(GCB)进行分散固相萃取净化,火焰光度检测器(FPD)进行分析测定,外标法定量。[结果]8种有机磷农药的检出限范围为0.001~0.008mg/kg,6次进样相对标准偏差小于5%,平均回收率范围为83.5%~101.2%。[结论]该方法前处理操作简单,检测的重复性好、精密度高,可满足对辣椒中多种有机磷农药残留的同时分析。     

农药残留快检仪可检蔬菜种类的研究

采用LZDN-16T蔬菜农残快检仪,对海南省常食用的10种类别,57个蔬菜品种进行快速检测。检测显示,可直接进行检测的蔬菜品种52个,经特殊处理后可检测的蔬菜品种4个、不可检测的蔬菜品种1个。     

湖北部分地区柑橘农药残留情况调查与分析

采用超高效液相色谱-串联质谱联用仪和气相色谱-串联质谱联用仪对湖北省宜昌市区、丹江口市、秭归县和兴山县的柑橘(Citrus reticulata Blanco)样品农药残留情况进行定量检测和分析.结果表明,柑橘样品农药残留的检出率高达91.9%,其中,禁用农药检出率为1.6%;限用农药检出率为9.5%;允许使用农药检出率为68.3%;未登记使用农药检出率为15.9%.农药使用情况较为普遍,不过由于禁、限用农药控制程度较好,因此柑橘质量整体安全性较高.     

杏鲍菇菌渣在甜瓜育苗上的应用

以常规育苗基质(草炭∶蛭石=2∶1)为对照(CK),探讨杏鲍菇菌渣复合基质对甜瓜育苗效果的影响。结果表明,菌渣复合基质的育苗效果均优于CK,其中菌渣∶草炭∶蛭石=2∶2∶1和菌渣∶椰糠∶蛭石=2∶2∶1效果最好,腐熟后的杏鲍菇菌渣可以部分或完全替代草炭进行甜瓜育苗。     

几种兽用合成抗菌药基于抗体快速检测技术研究进展

合成抗菌药在预防、治疗动物疾病等方面应用十分广泛,但不合理使用造成的耐药及残留问题日益严重,因此对兽用合成抗菌药的残留检测势在必行,而基于抗体的快速检测技术具有简便、灵敏度高、成本低等优点,发展前景十分广阔。作者综述了近年来针对磺胺类、氟喹诺酮类、喹噁啉类、硝基呋喃类、硝基咪唑类5大类兽用合成抗菌药物的抗体检测技术最新研究趋势,旨在促进残留快速检测技术的发展。     

非负矩阵Hadamard积谱半径上界的不等式

非负矩阵的Hadamard积是矩阵分析理论研究中的重要问题.在H9lder不等式的基础上,利用相似矩阵具有相同特征值这一特点给出两个n阶非负矩阵A和B的Hadamard积AB谱半径的上界,所得结果只依赖于两个非负矩阵的元素,便于计算.数值例子表明新估计式在一定条件下改进了现有的一些结果.     

中药渣堆肥过程中氮素转化及相关微生物菌群变化的研究

为了促进中药渣废弃物资源化利用,以中药渣、芦苇渣和酱油渣为原材料,采用不同配比和添加有机物料腐熟菌剂进行堆肥处理,分析堆肥过程中的温度、微生物总数(细菌、放线菌和真菌)、氮素相关微生物菌群(自生固氮菌、氨化细菌、硝化细菌、反硝化细菌)、全氮、铵态氮、硝态氮和种子发芽指数的变化,探讨不同处理堆肥前后养分变化差异的原因。结果表明,在中药渣不同配比堆肥过程中,细菌数量最多,是放线菌和真菌至少10 000倍,细菌、氨化细菌数量变化是"高—低—高—低"走势,而自身固氮菌、硝化细菌、反硝化细菌数量变化是"高—低—高"走势。中药渣∶芦苇渣∶酱油渣的配比为45∶30∶25时,升温快,温度基本上维持在62℃左右,堆肥前后氮素损失率为4.0%,堆肥结束时发芽指数为74.4%;而中药渣∶酱油渣的配比为75∶25时,升温慢,氮素损失率为53.3%,堆肥结束时发芽指数仅为34.4%。中药渣中的抑菌物质影响了不同处理堆肥过程中微生物总数和氮素相关微生物菌群的变化,导致了堆肥前后养分变化的差异。研究表明,中药渣∶芦苇渣∶酱油渣的配比为45∶30∶25时,氮素损失少,腐熟快。该研究为中药渣废弃物高温好氧快速堆肥、减少氮素损失提供参考和借鉴。