Microstructure–mechanical property relationship in an Al–Mg alloy processed by constrained groove pressing-cross route

The constrained groove pressing-cross route process was implemented on a commercially annealed AA5052 alloy at room temperature, with up to two passes (strain of ～4.64) along the rolling direction and transverse direction. The results showed the formation of an ultrafine-grained structure with an average sub-grain/cell size in the 300–500?nm range. The indentation hardness and tensile strength increased significantly, up to ～75 and 105%, respectively, and became more homogenous with a uniform and isotropic trend, as compared to the annealed alloy. According to the Hall–Petch and Taylor models used, grain refinement and increasing dislocation density were proposed as the main strengthening mechanisms. Fractographic studies revealed a ductile-fracture behaviour, with a dimpled structure proportional to the UFG structure.     

高伸长率冷轧双相钢DP980显微组织及性能

摘要：为了进一步提高冷轧双相钢DP980的强塑性，采用低C-Si-Mn-Nb-Cr成分，通过调整连续退火工艺参数，系统研究了工艺组织性能的关系，利用OM、SEM、EBSD分析了不同退火温度条件下各相的比例、尺寸、形貌、分布，同时利用力学拉伸试验手段研究了连退两相区退火温度对强塑性的影响。结果表明，通过优化调整连续退火工艺，不仅可以在冷轧铁素体和马氏体双相钢的组织上获得少量的残余奥氏体，也能细化再结晶晶粒，最终获得ReL/Rm≤0.5、高伸长率A50≥15%的冷轧DP980，提高强塑性的同时改善了成型性能。     

诱发IAF夹杂物与原晶粒的尺寸匹配关系

 对于氧化物冶金船板钢而言，细小弥散分布的夹杂物会对其原始晶粒产生钉扎和诱发晶内铁素体的双重作用，且研究发现诱发晶内铁素体的夹杂物尺寸与原始奥氏体晶粒尺寸存在一定的匹配关系。围绕上述问题进行了系统的分析研究和数据统计,结果表明，不同晶粒尺寸下，诱发晶内铁素体的夹杂物尺寸与原奥氏体晶粒度间存在近似线性关系，且随着奥氏体晶粒度的增大，诱发晶内铁素体的夹杂物尺寸则相应减小。     

我国粮油标准现状及问题分析研究

介绍了我国粮油标准体系的发展历程,以及目前我国粮油标准体系的构成和特点,分析了我国粮食标准及标准化存在的主要问题,并对完善我国粮油标准化工作提出了相应的建议。     

Back to the Origins: Background and Perspectives of Grapevine Domestication

Domestication is a process of selection driven by humans, transforming wild progenitors into domesticated crops. The grapevine (Vitis vinifera L.), besides being one of the most extensively cultivated fruit trees in the world, is also a fascinating subject for evolutionary studies. The domestication process started in the Near East and the varieties obtained were successively spread and cultivated in different areas. Whether the domestication occurred only once, or whether successive domestication events occurred independently, is a highly debated mystery. Moreover, introgression events, breeding and intense trade in the Mediterranean basin have followed, in the last thousands of years, obfuscating the genetic relationships. Although a succession of studies has been carried out to explore grapevine origin and different evolution models are proposed, an overview of the topic remains pending. We review here the findings obtained in the main phylogenetic and genomic studies proposed in the last two decades, to clarify the fundamental questions regarding where, when and how many times grapevine domestication took place. Finally, we argue that the realization of the pan-genome of grapes could be a useful resource to discover and track the changes which have occurred in the genomes and to improve our understanding about the domestication.     

42CrMo钢加热过程中的奥氏体晶粒尺寸演变

通过金相试验方法测定42CrMo钢在890~930 ℃下保温10~240 min后的晶粒尺寸。结果表明,42CrMo钢在加热到试验温度890~930 ℃时已经完全奥氏体化,保温过程中的晶粒生长属于正常生长;加热温度对晶粒尺寸的影响较大,保温时间对晶粒尺寸的影响较小;随保温时间的延长晶粒生长缓慢,晶粒尺寸与保温时间满足指数小于1的函数关系。基于试验数据,通过线性回归得到晶粒长大的Beck模型参数,通过非线性回归得到Sellars和Anelli模型参数,3个模型的预测精度都较好,而Anelli模型的适用性要高于Beck模型和Sellars模型,故在预测42CrMo钢的奥氏体晶粒长大规律时宜使用Anelli模型。     

Segregation of dockage and foreign materials in wheat during loading into a 10-m diameter corrugated steel bin

Segregation of dockage and foreign materials (DFM) is an unavoidable phenomenon in bulk grain and causes many problems. In this study, distributions of DFM, and shrunken and broken kernels (SBK) were determined during loading of wheat in a 10-m diameter flat-bottom cylindrical bin. Wheat was loaded through a vertical funnel (spout) into the bin from five drop heights (1.6, 2.5, 3.4, 4.3 and 5.2 m). Samples were collected using a sampling tube (29 cm diameter and 50 cm deep) inserted vertically at five locations (0.00, 1.25, 2.50, 3.75 and 5.00 m of horizontal distances from the center) along three radii of the bin for each drop height. The impurities from each collected sample were divided into five categories with different sizes (other grains, other particles, SBK, fine particles, and dust and fragments) by sieving analyses. Impurities larger and smaller than wheat kernels were categorized as large and small impurities, respectively. Drop height significantly influenced the radial distribution of fine particles, dust and fragments, but not the distribution of other grains and other particles. Fine particles and dust and fragments mainly accumulated in the center, while SBK accumulated mostly near the wall of the bin. Both true density and apparent test weight (bulk density) of unclean wheat and test weight of clean wheat significantly changed along the radius of bin. Apparent test weight of unclean wheat was minimum in the center and close to the wall of bin. Drop height did not influence true density and apparent test weight of clean and unclean wheat. Thousand kernel weight, dimensions, and sphericity of wheat kernels were similar at different radial locations of bin for all drop heights. This study can be used as a reference for further studies on grain handling and associated effects on grain grading system and design of aeration, drying, and insect control. .     

Effects of developmental stage,cold acclimation and diet on the cold tolerance of three species of Cryptolestes (Coleoptera: Laemophloeidae)

Flat grain beetles (Coleoptera: Laemophloeidae) are common stored-product insect pests in Canada, infesting cereals in grain bins, equipment and end products in flour mills. We studied the cold tolerance of the three most common flat grain beetles: Cryptolestes ferrugineus, Cryptolestes turcicus and Cryptolestes pusillus, by measuring the survival at −10 °C and supercooling point (SCP) for different life stages (egg, young larva, old larva, pupa and adult) reared on flour mixed with brewer’s yeast. Probit analysis was used to estimate the lethal time for 50 and 95% mortality. This was done with non-acclimated individuals (only held at 30 °C) or cold-acclimated individuals (held at 18, 10 and 5 °C, for 1 week/temperature). In general, adults were the most cold-hardy stage for each of the species. Acclimated insects were anywhere from no increase in cold tolerance to 14-fold more cold-tolerant than the corresponding non-acclimated stage and species. Cryptolestes ferrugineus was most cold-tolerant species (58 d at −10 °C to reach 95% mortality for acclimated adult), C. turcicus was the next most cold-tolerant, (39 d) and C. pusillus was the least cold-tolerant (11 d). The cold tolerance of adults reared on three diets was measured both for acclimated and non-acclimated insects. The adults reared on grain diet (whole wheat kernels, cracked wheat kernels and wheat germ (90:5:5 mass ratio) were the most cold-tolerant, adults reared on white-wheat flour and brewer’s yeast diet (95:5 mass ratio) had the next highest cold tolerance followed by the adults reared on 100% white-wheat flour. Supercooling point (SCP) of insects ranged from −20.6 to −26.7 °C. In general, acclimated insects had slightly lower SCP than non-acclimated insects.