Uni- and bimodal Weibull distribution for analyzing the tensile strength of Diss fibers

The present work considered several statistical distribution functions with the aim to critically analyze the strength data of natural Diss fibers. Besides the Weibull two-parameter distributions, three-parameter and bimodal Weibull were used. Kolmogorov–Smirnov, Anderson–Darling and chi-square goodness-of-fit test were used to judge how accurate the theoretical Weibull probability density function (PDF) fits with tensile strength data.

Tensile test results indicated that the fibers have good tensile strength and Young’s modulus. However, their fracture strength exhibits high scatters due to the presence of defects within the fiber and/or on the fiber surface. Microscopic observation revealed that the rupture of the fibers is governed by two types of defects, the rough surface of the fiber formed by several spines and the internal defects such as the defects of connection between fibrils.

The statistical analysis of variability in strength showed that the results of the shape and scale parameters calculated using bimodal Weibull distribution give larger values compared to those using the single Weibull distribution. Also, the strength data points fit well to the bimodal Weibull PDF curve. All three goodness-of-fit tests indicated also that the bimodal Weibull model gives a more accurate prediction of data strength compared to the unimodal Weibull model.     

球形芽孢杆菌对酒曲害虫大谷盗的毒杀效果研究

球形芽孢杆菌(Bacillus sphaericus)LPl-G茵株能产生对害虫有毒杀作用的毒蛋白.采用该菌种防治酒曲害虫大谷盗,结果表明,在30℃下,湿度73%～75%条件下,球形芽孢杆菌的有效杀虫剂量为4mL/100g,可使大谷盗的校正死亡率达91.4%,且杀虫后大曲的糖化力、发酵力、微生物的数量变化极小.     

球形芽孢杆菌对酒曲害虫黑菌虫的毒杀效果

球形芽孢杆菌(Bacillus shpaericus)是一种能产生对害虫具有专一杀虫活性蛋白的细菌,试验首次采用该菌种防治酒曲害虫黑菌虫.试验结果表明,球形芽孢杆菌液体制剂0.008mL/g,在30℃条件下24d黑菌虫校正死亡率达到100%,对大曲质量的影响较小.     

苏云金芽孢杆菌和白僵菌混配对酒曲害虫大谷盗的毒杀效果研究

利用苏云金芽孢杆菌与白僵菌混配杀灭酒曲害虫大谷盗。研究结果表明：在温度30℃、相对湿度为60%～69%条件下,苏云金芽孢杆菌与白僵菌液体制剂按1∶1比例混配后,使用量为4.5mL时,在杀虫第24d可使大谷盗的死亡率达96.0%,校正死亡率达94.7%。与试验前相比,酒曲的糖化力、液化力、发酵力分别下降了19.4%、19.8%、7.4%;而空白对照组则明显下降,分别下降37.5%、45.2%、29.7%。