农药登记中残留田间实验采样的研究进展和方法

科学的采样能使残留实验得到接近采样目标真实残留量的数据,直接影响残留量是否超标的界定和采样的代表性.提出了采样的原则和方法、影响因素及实际操作中的采样方案;介绍了国际通用的采样准则,解释采样误差的原因,提出应加强对采样过程的质量控制,为采样标准化的建立提供理论支持.     

对“期间核查”实施方法的探讨

讨论了检验用仪器设备“期间核查”的方法及其应用     

胎面动态连续分选秤的校准方法和不确定度分析

轮胎制造过程中,需要对轮胎部件中的胎面重量进行称量和控制,对胎面进行称量常规采用的是动态连续分选秤,由于动态连续分选秤与胎面生产线同时工作,现场使用环境复杂,影响称量结果因素较多.文章介绍了动态连续分选秤校准方法,并给出了测量值的不确定度,希望能提供给各位同行一点建议和帮助.     

浅谈原子吸收光谱法测定矿石中金含量的不确定度评定

测量结果的不确定度是指在测量过程中产生的随机不确定性。测得的数据总在一定范围内波动,总是有误差的,虽然不能得到误差的具体值,但可以根据测量的过程评定出误差的范围,即不确定度。在给出测量数据的同时再给出不确定度的大小才是完整的。本文以原子吸收光谱法检测矿石中金含量的不确定度评定的方法为例,给出一般实验测试分析中原子吸收仪器法检测的不确定度评定方法。     

密度球的校准方法及其不确定度评定研究

本文主要介绍了一种可行的密度球的校准方法,并对其密度的示值误差进行了合理的不确定度评定,由于目前密度球尚无国家校准规范,故本文为计量及仪器使用人员对密度球的校准或性能确认提供了参考。     

HPLC法测定蜂蜜中果糖、葡萄糖的不确定度评定

对高效液相色谱法测定蜂蜜中果糖、葡萄糖含量的不确定度来源进行分析讨论,建立其结果的数学模型,计算其不确定度分量、结果的标准不确定度及扩展不确定度,得出结果的相对不确定度为1.8%.此方法可适用于高效液相色谱法测定蜂蜜中果糖、葡萄糖含量的不确定度评定.     

气相色谱分析方法的准确度探讨

在仪器技术性能最佳状态下,用同一试样,在同一台仪器操作参数完全一致条件下,由不同操作者连续六次使用注射器手动进样,分析进样所得数据,并讨论了手动进样引入的误差范围和极限值。     

大口径电磁流量计的检定方法研究与探讨

为了加强大口径流量计的校验,提高计量精度,针对标准表法对大口径电磁流量计的实验室与现场检定进行综述,分析各自的栓定特点及选用的标准装置,重点对不确定度以及现场检定需注意的事项进行分析。     

定电位电解法固测定污染源排气中二氧化硫的不确定度评定

测量不确定度是与测量结果紧密相关的参数,用于表征测量结果合理分散性。在实验室数据质量控制上不可惑缺。本文根据《固定污染源排气中二氧化硫的测定定电位电解法》(HJ/T57-2017)标准方法及不确定度评定方法,通过分析评估烟气分析仪测量固定污染源烟气中二氧化硫的影响因素,进行测量不确定度评定,以校准结果。最终计算得出相对扩展不确定度度为6. 76%,K=2。     

Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

Studies on simultaneous saccharification and fermentation (SSF) of wheat bran flour, a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation. Experiments based on central composite design (CCD) were conducted to maximize the glucose yield and to study the effects of substrate concentration, pH, temperature, and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungal α-amylase and the above parameters were optimized using response surface methodology (RSM). The optimum values of substrate concentration, pH, temperature, and enzyme concentration were found to be 200 g/L, 5.5, 65°C and 7.5 IU, respectively, in the starch saccharification step. The effects of pH, temperature and substrate concentration on ethanol concentration, biomass and reducing sugar concentration were also investigated. The optimum temperature and pH were found to be 30°C and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation at optimum conditions of pH and temperature. The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model. Simultaneous saccharificiation and fermentation of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.     

Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

Studies on simultaneous saccharification and fermentation (SSF) of wheat bran flour, a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation. Experiments based on central composite design (CCD) were conducted to maximize the glucose yield and to study the effects of substrate concentration, pH, temperature, and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungal α-amylase and the above parameters were optimized using response surface methodology (RSM). The optimum values of substrate concentration, pH, temperature, and enzyme concentration were found to be 200 g/L, 5.5, 65°C and 7.5 IU, respectively, in the starch saccharification step. The effects of pH, temperature and substrate concentration on ethanol concentration, biomass and reducing sugar concentration were also investigated. The optimum temperature and pH were found to be 30°C and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation at optimum conditions of pH and temperature. The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model. Simultaneous saccharificiation and fermentation of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.