Addressing rice germplasm genetic potential using genotypic value to develop quality core collections

Near‐infrared reflectance spectroscopy was used to address the genetic potential for 990 rice lines for 26 quality traits. The predicted genotypic values for quality traits were calculated using the Mahalanobis distance method and used to measure the genetic similarities among rice varieties. To make the core collection, Manhalanobis distance was employed to calculate the genetic distance among the accessions, and the hierarchical clustering method was used to group the accessions, accompanied by sampling method under the pre‐concerted sample proportion (i.e., the ratio of accessions in the core collection to those in the initial population). In this experiment, 24 core collections were developed by using eight hierarchical clustering methods, combined with random, preferred and deviation sampling at a sample proportion of 15% (i.e., 149 for the 15% core collection). These core collections were compared with others constructed at sample proportions of 10% and 20% (i.e., 99 for the 10% core and 198 for the 20% core, respectively). In addition, a trend at increasing sample proportion from 5% to 60% showed that core collection development could be achieved at a sample proportion range of 10–25%. Further results revealed that deviation sampling strategy in combination with the single linkage method retained the greatest degree of genetic diversity of the initial collection. The core collection developed using a sample size of 15% retained the highest degree of diversity, and was stable for all the cluster methods and, hence, the best in developing a core collection of rice quality traits. Copyright © 2006 Society of Chemical Industry     

美棉的品级鉴定

针对美棉的特点，提出了美棉检验抽样方法及数量，品级鉴定把握的要点，以及不符合品级的处理方法。     

缩小分散/士林大小样染色色差的实践

在分散/士林轧染中,符样率是制约生产的难点。通过对如何缩小大小样的差距、大小样轧染工艺条件的差异及其控制进行讨论和分析,对轧液及轧液率,烘干、焙烘/汽蒸条件和烧碱/保险粉用量,以及后处理水洗、皂洗、拉幅,以及染料的优选提出改进措施,以便统一大小样工艺条件,缩小大小样色光差异。     

Performance of new clean-up column for the determination of ochratoxin A in cereals and foodstuffs by HPLC-FLD

The performance of the newly developed Mycosep® 229 Ochra and Multisep® 229 Ochra clean-up columns for ochratoxin A (OTA) determination was evaluated. OTA was subsequently analysed using RP-HPLC with fluorescence detection. Recoveries for frequently contaminated commodities, like cereals, red wine, raisins and green coffee, were estimated. The recoveries obtained for the Mycosep 229 Ochra column were in the range from 87.9 ± 12.5% (n = 6) for wheat to 99.4 ± 2.7% (n = 24) for raisins. For Multisep 229 Ochra, recoveries from 76.5 ± 8.0% (n = 6) for barley to 86.4 ± 1.4% (n = 24) for raisins were achieved. Limits of detection for all matrices investigated (maize, wheat, rice, barley, raisins, green coffee beans, red wine) were in the range 0.4-2.4 μg kg^-1. The trueness of the method was tested using a certified reference material.     

基于LCD-SE-IWOA-KELM的短期风电功率区间预测

针对风电功率的不确定性、随机性以及已有的风电功率点预测无法反应其不确定性信息的问题,提出了基于局部特征尺度分解(LCD)-样本熵(SE)和改进鲸鱼优化算法(IWOA)优化核极限学习机(KELM)的短期风电功率区间预测模型。采用LCD分解来降低原始风电功率序列的非平稳性,通过测量各ISC分量的样本熵来重构新的序列以降低过多的分量对预测精度带来的影响,然后分别建立各新序列的区间预测模型,最后将各新序列的预测结果进行叠加获得最终预测结果。采用改进的WOA算法优化核极限学习机的参数。实验仿真表明,文中所提模型能够获得良好的区间预测结果,具有一定的实际意义和应用价值。     

The polymerase chain reaction: Applications for the detection of foodborne pathogens

Faster methods for the detection of foodborne microbial pathogens are needed. The polymerase chain reaction (PCR) can amplify specific segments of DNA and is used to detect and identify bacterial genes responsible for causing diseases in humans. The major features and requirements for the PCR are described along with a number of important variations. A considerable number of PCR‐based assays have been developed, but they have been applied most often to clinical and environmental samples and more rarely for the detection of foodborne microorganisms. Much of the difficulty in implementing PCR for the analysis of food samples lies in the problems encountered during the preparation of template DNAs from food matrices; a variety of approaches and considerations are examined. PCR methods developed for the detection and identification of particular bacteria, viruses, and parasites found in foods are described and discussed, and the major features of these reactions are summarized.     

食品中化学危害物检测的样品前处理方法选择及开发策略

食品中化学危害物种类多,含量一般在痕量和超痕量水平;食品基质复杂,要在低含量水平获得可靠的检测结果,选择合适样品前处理技术至关重要。本文针对不同类别化合物的检测需要,根据不同食品基质的特性及分析目的,依靠近10年来食品化学危害物的样品前处理方法开发经验,探讨样品前处理技术的选择,综述前沿技术进展。提出基于“食品基质”和“分析目标物”的具有实际应用性的前处理方法选择策略,并结合应用实例,提出针对性前处理方法开发的建议,旨在为基层技术人员选择可靠的前处理方法提供借鉴。     

样品整经机的工作原理及技术特点

样品整经机是一种全新的整经设备,即最少只用1只筒子经过整经即可形成织轴,是用于织造包袱样、米样和小批量产品进行整经的专用设备.这种整经方式可大大减少整经筒子量,简化工艺流程,降低生产成本,减少出样时间,尤其适用于小批量织物生产.并且经后整理加工后得到的小样织物在风格、性能上接近批量生产的产品.文章结合国产GA 193样品整经机的特点,讨论了样品整经的基本原理,分析了样品整经机的主要机构,并对样品整经机与分条整经设备进行了技术经济分析比较.     

生丝回潮率检验样丝绞数的探讨

将生丝回潮率检验的样丝随机分为两组，并将分组单独测试回潮率的结果与其平均值进行比较，按置信区间计算方法判定生丝回潮率检验样丝绞数在保证检验结果准确的前提下，可在现行标准规定的基础上减少一半，从而节约大量的样丝，给生产企业带来经济效益。     

Within-herd prevalence threshold for the detection of Mycobacterium avium ssp. paratuberculosis antibody–positive dairy herds using pooled milk samples: A field study

Herd-level diagnosis of paratuberculosis using a pool-milk ELISA (pool size: n ≤ 50) is a novel, economical, and convenient method to identify blood serological Mycobacterium avium ssp. paratuberculosis (MAP) antibody–positive herds. To date, the diagnostic performance of the pool-milk ELISA has been described only under laboratory conditions where herd prevalence was simulated by the preparation of milk pools consisting of milk samples of cows with a known MAP status determined by fecal culture. In our observational study, test performance under field conditions was studied using pooled milk and individual blood samples. A total of 486 herds within the MAP prevalence reduction program of Lower Saxony, from which pooled milk and individual blood ELISA results were available, were assigned to this study. Data were analyzed for the period between January 1 and December 31, 2018, the first year after herd testing became obligatory in this federal state of Germany. To evaluate whether pooled milk samples reliably distinguish between herds with a MAP-apparent blood serological within-herd prevalence (MAP-Ab-WHP_app) ≥5% and herds with a MAP-Ab-WHP_app <5%, the distribution of the MAP-Ab-WHP_app was compared between pool-positive and pool-negative herds. The MAP-Ab-WHP_app was 3.4% (median; 95% confidence interval = 0–11.4%) in pool-positive herds and 1.2% (median; 95% confidence interval = 0–6.4%) in pool-negative herds. Only 10.8% (n = 12) of the pool sample–negative herds had a MAP-Ab-WHP_app ≥5% and were therefore false negatives, given the aims of the MAP prevalence reduction program. Hence, the pool-milk sampling strategy seems well suited to distinguish between herds with a MAP-Ab-WHP_app ≥ 5% and herds with a MAP-Ab-WHP_app <5% since only 10% of serum MAP-ELISA positive herds were missed. Employing a logistic regression model, we estimated that the minimum blood serological MAP-Ab-WHP_app to detect a pool-positive herd with a probability of 95% was 8%, which fits well with the aim of the MAP prevalence reduction program to focus on herds with a MAP-Ab-WHP_app of ≥5%. Despite the limitations of the control approach, which include milk pool sample collection and a low sensitivity of the ELISA used in milk pools and serum samples, the aims of the MAP prevalence reduction program can be achieved. The results of these field data support that pool-milk sample ELISA is a useful, economical, and low labor–intensive tool to identify herds seropositive for MAP in a MAP prevalence reduction program.