焊丝中Si元素含量对铝合金接头裂纹敏感性的影响规律及机理

使用扫描电镜、能谱、温度场实时采集等测试方法，研究了焊丝中Si含量对AA6063铝合金GMAW焊接头热裂纹敏感性的影响规律及机理. 结果表明，当焊丝为纯铝时，鱼骨试样的焊缝中心会出现细长的焊接裂纹；当焊丝中的Si含量为4.5% ~ 6%时，裂纹的长度变短，但是开裂距离明显增加；当焊丝中的Si含量达到11% ~ 13%时，试样焊缝无裂纹出现. 随着Si含量的不断提高，合金易出现裂纹的凝固温度区间先增大后减小；焊丝中Si含量的不同还会影响凝固后期金属液的流动性，使得焊缝晶界处的物相成分和形态都有明显的区别；同时，Si含量的提高会使得接头的冷却速度先增加后减小，从而导致应力状态改变，热裂纹敏感性先升高后降低.     

Rapid Discovery of Aspartyl Protease Inhibitors Using an Anchoring Approach

Pharmacophore searches that include anchors, fragments contributing above average to receptor binding, combined with one-step syntheses are a powerful approach for the fast discovery of novel bioactive molecules. Here, we are presenting a pipeline for the rapid and efficient discovery of aspartyl protease inhibitors. First, we hypothesized that hydrazine could be a multi-valent warhead to interact with the active site Asp carboxylic acids. We incorporated the hydrazine anchor in a multicomponent reaction and created a large virtual library of hydrazine derivatives synthetically accessible in one-step. Next, we performed anchor-based pharmacophore screening of the libraries and resynthesized top-ranked compounds. The inhibitory potency of the molecules was finally assessed by an enzyme activity assay and the binding mode confirmed by several soaked crystal structures supporting the validity of the hypothesis and approach. The herein reported pipeline of tools will be of general value for the rapid generation of receptor binders beyond Asp proteases.     

Extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins: part I – Effect of moisture content

This study investigated the effects of moisture content (MC) on the physicochemical properties of extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins. Samples were extruded at 170 °C (maximum barrel temperature), at 3.6 kg h⁻¹ (liquid feed rate) and at 1.8, 2.2, 2.6 and 3.0 kg h⁻¹ (dry feed rates) to obtain MC of 60%MC, 56%MC, 52%MC and 49%MC, respectively. Meat alternatives at 52%MC showed the greatest degree of texturisation. However, meat alternatives at 49%MC were the closest in terms of both textural and microstructural properties to reference sample, boiled chicken breast. Results from protein solubility suggested that a large amount of aggregated proteins were associated with hydrogen bonds, while disulphide bonds were the main contributor in the formation of fibrous structure in meat alternatives. Results showed that the change in MC as process parameter played an important role in the formation of fibrous structure in extruded meat alternatives.     

稀土La2O3改性脲醛树脂的黏度特性研究

脲醛树脂(UF树脂)胶黏剂具有胶合强度高、制作简单、成本低廉、原料来源丰富等一系列特点,成为我国人造板生产的主要胶种,是市场上需求量最大的胶黏剂之一。但由于在固化时会放出刺激性的甲醛,游离甲醛高,在使用时严重危害人的健康。近年来,随着人们环保意识的提高,生产和使用低毒UF树脂胶势在必行。本文介绍了稀土氧化镧对脲醛树脂的改性过程并对改性后脲醛树脂胶的各项性能进行了测试。本实验通过在不同反应阶段加入稀土氧化镧,分别探讨它们对脲醛树脂胶黏剂性能影响。实验表明:在脲醛树脂胶中加入稀土氧化镧可以增加黏度、固化时间、固含量,并可以减少游离甲醛释放量。     

Characteristics of fat,and saponin and tannin contents of 11 varieties of rambutan (Nephelium lappaceum L.) seed

Rambutan seed is discarded during fruit processing. However, the seed contains a considerable amount of crude fat. Hence, the objective of this study was to determine two anti-nutritional constituents, namely saponin and tannin, and to characterize the fat of the seeds of 11 varieties of rambutan fruit. Results showed that the range of crude fat content is fairly narrow (36.13–39.13 g/100 g dried seeds). The iodine value and free fatty acid content of the fat were 38.50–50.61 g I₂/100 g fat and 0.99–2.18% as oleic acid, respectively. Oleic (33.35–46.64%) and arachidic (26.03–33.27%) acids were the main fatty acids in the fat. HPLC analysis showed that the fat comprised mainly five unknown triacylglycerols (83.94–95.33%). The melting and crystallization curves showed that the fat exhibited four to nine non-distinct peaks. The complete melting and crystallization onset temperatures of the fat were 24.8–50.6°C and 24.1–39.4°C, respectively, while the melting and crystallization enthalpies of the fat ranged from 71.2 to 141.7 J/g and from 60.4 to 88.9 J/g, respectively. At 0°C, the solid fat index of the fat ranged between 87.4% and 91.6% and the fats of some varieties melted completely at human body temperature. The saponin and tannin contents of the seed were 14.27–18.96 mg soya saponin/100 g and 4.40–26.68 mg catechin equivalent/100 g, respectively. Findings showed that rambutan seed fat has potential to be used in various sectors of food industry.     

日本寒冷地带北海道优良食味粳稻育种研究（网络首发、推荐阅读）

长久以来，北海道产大米的食味口碑一直不高，也未出现像“越光”一样全日本知名的优良食味品种，因此，自1980年开始历时28年，北海道立（现称道总研）农业试验场致力于粳稻优良食味品种快速研究项目的实施。为实现快速研发的目标，通过世代促进栽培法和花药培养法成功缩短了育种年限；采用扩大育种规模的方式，并利用优良食味、耐寒性等内外部有效基因培育兼具优良食味及早熟耐寒性的品种；初期世代开始主要通过分析大米的蛋白质含量、尤其是直链淀粉含量，中间世代则通过少量蒸饭的方式进行食味品鉴，选育出优良食味种系。在食味遗传基因的改良方面，先是集聚北海道优良食味的遗传基因培育出品种“雪光”，再经由北海道品种引进“越光”的优良食味遗传基因，之后以日本东北优良食味遗传基因品种“秋田小町”作为直接杂交母本，分别成功培育出品种“闪光397”和“星之梦”，其直链淀粉含量与以往多肥多产品种的22%相比降低了2%。在此基础之上，引进美国品种“国宝玫瑰”优良食味遗传基因的品种“七星”成功问世，其直链淀粉含量又降低了1%；以变异低直链淀粉种系“北海287号”为母本，成功培育出“梦美”，其直链淀粉含量15%~16%，粘度和软度俱佳，食味亦可与“越光”媲美。     

What drives smartwatch purchase intention? Perspectives from hardware,software, design,and value

Although wearable devices are popular in recent years, the market share of smartwatches is relatively low. The main goal of this research is to investigate the antecedents of the intention to purchase a smartwatch. This research develops a conceptual model and hypotheses based on the theory of reasoned action and perceived values from the perspectives of software, hardware, and aesthetic design. An online questionnaire was developed and distributed on popular websites to collect data, and 260 usable responses are collected from the potential users of the Apple Watch in Taiwan. The thirteen hypotheses were validated by using partial least squares (PLS) techniques. Among the antecedents of purchase intention in the model, the attitude towards using smartwatches was found to have the strongest direct effect. Among the factors of the attitude, design aesthetics have the most significant effect. The results also show that all of the factors about smartwatch attributes directly affected the related perceived values. However, social value and performance/quality value did not affect the intention. The model demonstrated relatively good explanatory power for purchase intention in the context of smartwatches. The proposed model can provide insights to smartwatch vendors to develop their new products and marketing strategies.     

砂土内微生物诱导碳酸钙结晶的检测方法研究

为了寻找砂土中微生物诱导碳酸钙结晶(MICP)过程的无损检测方法,采用3种粒径的砂子和两种浓度的胶结溶液进行了砂土的胶结试验,检测了砂土流出液的流量、p H值、尿素浓度和Ca2+浓度等化学指标变化情况,并对碳酸钙晶体的生成数量和分布进行了分析。试验结果显示:砂土流出液的流量和Ca2+浓度能够预测MICP过程中碳酸钙晶体的生成数量,p H值和尿素浓度能够预测MICP过程中尿素的水解程度;砂土中碳酸钙晶体的生成数量与注入的Ca2+总量呈现线性增长的关系,其线性系数可以通过砂土的粒径和胶结溶液的浓度表示,胶结后砂柱的碳酸钙分布并不均匀,小粒径的砂柱上部碳酸钙含量较高,而大粒径的砂柱下部碳酸钙含量较高。     

3D Microstructures of Liquid Crystal Networks with Programmed Voxelated Director Fields

The shape-shifting behavior of liquid crystal networks (LCNs) and elastomers (LCEs) is a result of an interplay between their initial geometrical shape and their molecular alignment. For years, reliance on either one-step in situ or two-step film processing techniques has limited the shape-change transformations from 2D to 3D geometries. The combination of various fabrication techniques, alignment methods, and chemical formulations developed in recent years has introduced new opportunities to achieve 3D-to-3D shape-transformations in large scales, albeit the precise control of local molecular alignment in microscale 3D constructs remains a challenge. Here, the voxel-by-voxel encoding of nematic alignment in 3D microstructures of LCNs produced by two-photon polymerization using high-resolution topographical features is demonstrated. 3D LCN microstructures (suspended films, coils, and rings) with designable 2D and 3D director fields with a resolution of 5 µm are achieved. Different shape transformations of LCN microstructures with the same geometry but dissimilar molecular alignments upon actuation are elicited. This strategy offers higher freedom in the shape-change programming of 3D LCN microstructures and expands their applicability in emerging technologies, such as small-scale soft robots and devices and responsive surfaces.