Synergistic effect of high-intensity ultrasound and β-cyclodextrin treatments on browning control in apple juice

This work evaluated the synergistic effects of combined high-intensity ultrasound (HIU) with β-cyclodextrin (β-CD) treatments on inhibiting browning of apple juice and explored the mechanism through simulation system. The combined treatment of 300 W HIU with 0.006 g mL⁻¹ β-CD had a synergistic impact on maintaining juice colour, resulting in a 39.06% reduction in browning degree, only a 36.64% decrease in total phenolic content, and a 17.82% reduction in PPO activity. The inhibition of enzymatic browning in simulated system revealed that HIU suppressed the enzyme (Polyphenol oxidase, PPO) and β-CD inhibited enzyme (PPO) and embedded substrate (polyphenol). The results of spectroscopic analysis showed that the particle-size distribution of PPO narrowed, the content of α-helix in the secondary structure increased, the fluorescence intensity increased, and the maximum wavelength was red-shifted after HIU and β-CD treatment. Changes in structure could further result in PPO activity loss. Hence, the combined treatment could synthetically alleviate the browning of apple juice.     

Scallops as a new source of food protein: high-intensity ultrasonication improved stability of oil-in-water emulsion stabilised by myofibrillar protein

In this study, the effect of high-intensity ultrasound (HIUS) (200 and 400 W for 0, 5, 10 and 15 min respectively) on conformational changes, physicochemical, rheological and emulsifying properties of scallop (Patinopecten yessoensis) myofibrillar protein (SMP) was investigated. HIUS-treated SMP had lower α-helix content and higher β-sheet content compared with the native SMP. HIUS treatment induced the unfolding of SMP and increased the surface hydrophobicity. The particle size of SMP decreased and the absolute zeta-potential increased after ultrasonication, which in turn increased the solubility of SMP. The conformational changes and the improvement of physicochemical properties of SMP increased the ability for SMP to lower the interfacial tension at the oil–water interface and increased the percentage of adsorbed protein. As a result, the emulsifying properties, rheological properties of SMP and storage stability of emulsions were also improved. In conclusion, HIUS treatment has future potential for improving the emulsifying properties of SMP.     

Impact of high-intensity ultrasound on physical properties and degree of oxidation of lipase modified menhaden oil with caprylic acid and/or stearic acid

The purpose of this research was to determine the effect of high-intensity ultrasound (HIU) on physical properties, degree of oxidation, and oxidative stability of structured lipids (SLs). Caprylic acid (C) and stearic acid (S) were incorporated into menhaden oil using Lipozyme® 435 lipase to obtain five samples: (1) LC 20 (menhaden oil with 20% of C), (2) LC 30 (menhaden oil with 30% C), (3) LS 20 (menhaden oil with 20% S), (4) LS 30 (menhaden oil with 30% S), and (5) Blend C (menhaden oil with 16.24% C and 13.04% S). Samples were crystallized for 90 min at the following temperatures: (1) LC 20 at 15.5°C, (2) LC 30 at 17.5°C, (3) LS 20 at 24°C, (4) LS 30 at 30°C, and (5) Blend C at 18.0°C, and HIU was applied at the onset of crystallization. Physical properties, degree of oxidation, and oxidative stability were evaluated in sonicated and nonsonicated samples. All SLs had statistically higher G′ after sonication. Sonicated LS 30, LC 30, and Blend C had a higher melting enthalpy than the nonsonicated ones, while enthalpy values in sonicated LS 20 and LC 20 samples were not statistically different than the nonsonicated ones. No significant difference between sonicated and nonsonicated samples was observed in peroxide values (1.2 ± 0.1 meq/kg, p > 0.05) and in the oxidative stability index (6.3 ± 0.2 h, p > 0.05). These results showed that HIU was effective at changing physical properties without affecting the oxidation of the samples.     

湾图沟煤矿高强度采动巷道稳定性评价研究

针对高强度采动巷道围岩控制难题，从实验室岩样尺度和现场巷道尺度研究了湾图沟煤矿13405工作面回风平巷围岩稳定性特征。结合单轴压缩试验和声波测试分析了干燥、自然及饱和状态下3组岩样的力学行为差异特征。利用钻孔成像，分析了高强度采动影响巷道围岩裂隙发育分段特征。结果表明:干燥、自然及饱和状态下岩样的单轴抗压强度和弹性模量依次降低，水分的存在极大地降低了岩石的强度和刚度。实煤体段围岩仅在深度1 m范围内发现少量纵向裂隙。高静压段两帮维护效果较差，煤帮裂隙极为发育，存在高量值的离层。动压段巷道顶板完整性较好，两帮均发现较大离层，且超出了锚杆正常锚固范围，严重影响了巷道锚固结构的稳定性。     

黄土高原多沙粗沙区高含沙水流发生频率的时间变化

高含沙水流的频繁发生是黄土高原多沙粗沙区产生高强度侵蚀的重要原因。本文基于1967—1989年的系列泥沙资料和面雨量资料，分析了黄土高原多沙粗沙区8个流域高含沙水流发生频率随时间的变化过程。根据其不同的变化趋势，将研究区所有流域分成了两类。第一种类型高含沙水流发生频率随时间逐渐减小；第二种类型高含沙水流随时间呈先减小后增大的变化趋势。从汛期降雨量（6—9月）及人类活动（包括人为的减沙活动和人为增沙活动）两个方面对高含沙水流随时间变化趋势的产生原因进行了分析。结果表明，第一种类型主要受到同期汛期降雨量的减少以及各种水利水保措施减沙量从上世纪60一80年代逐渐增大的影响；第二种类型的流域在上世纪60年代末到80年代初高含沙水流发生频率的减小主要是因为上世纪60、70年代大量修建的淤地坝在70年代发挥了显著的拦减泥沙的作用；但到了80年代以后，新建淤地坝很少。原有淤地坝已大部失效，另外人为的增沙活动，如修路、开矿、建窑等活动在80年代以后显著增加，上述因素促使高含沙水流发生频率在80年代初期以后呈随时间增加的趋势。     

基础锚栓预埋加固方案

结合工程实例 ,介绍轻钢结构系统基础锚栓预埋、加固解决方案 ,并介绍了加固系统的制作及使用方法 ,可供工程人员参考     

强流脉冲离子束表面再制造技术原理与应用

采用TEMP-6型强流脉冲离子束(HIPIB)装置开展了HIPIB表面再制造技术的研发.HIPIB装置主体由高压脉冲电源系统和高功率离子二极管系统组成,通过高压短脉冲在二极管中放电产生阳极等离子体并引出ns级强流离子束.HIPIB辐照材料表面,发生显著的熔融、蒸发和剧烈烧蚀,物质喷射的反冲作用在辐照表面形成由表及里的应力波,导致材料表层强烈的热-力学效应.利用HIPIB与材料表面的相互作用,应用于涡轮叶片表面的清洗维修,可有效去除涡轮叶片基体因高温氧化形成的氧化物,伴随表层的重熔将叶片基体表面微观缺陷焊合,获得了光滑、平整的涡轮叶片修复表面.实现了HIPIB辐照在涡轮叶片表面再制造方面的应用.     

低强度锚固体养护时间和频率对导波速度的影响

组装了一套超声导波无损检测系统.制作了两个长度为1 m,28 d锚固体单轴抗压强度分别为4.36 MPa和4.69 MPa的全锚锚杆.利用该系统对这两个锚杆在各个养护期,从40～100 kHz的超声导波速度进行了测试,以研究水泥砂浆的养护期和导波频率对波速的影响.研究结果表明,在测试频率范围内,低强度锚固锚杆中导波速度随频率的增加而增加,在试件1和试件2中分别增加了10.1%和8.2%;水泥砂浆的养护期对导波速度影响也很大,尤其在养护初期速度随时间的增加而明显下降,最大降幅达29.4%(养护第7天),但在中后期波速变化不太明显,只有略微上升.试验结果与理论分析相吻合.     

Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt

In order to establish the design method for T-shaped tensile connector with high strength bolt,the theoretical analysis is carried out. Firstly,it analyzes the performance of the connector and establishes prying force calculation model. Based on the model,prying force equation and function between bolt prying force and flange thickness is derived,and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally,two simplified design methods of the connector are proposed,which are bolt pulling capacity method and flange plate bending capacity method.     

某特大简支梁桥墩身开裂的事故排查

桥梁裂缝严重影响结构安全性和耐久性,不符合“绿色建造”和“可持续发展”的相关理念。文章对某特大简支梁桥桥墩开裂现象进行事故排查,为裂缝修复工作提供依据,以促进桥梁施工各个环节的规范化。考虑支座中未拆除的临时连接螺栓对墩、梁的约束作用,首先以Abaqus分析未拆除的临时连接螺栓对支座水平剪切变形的约束作用,然后以Midas计算了3种最不利工况下桥墩墩顶处的支座反力,最后以ANSYS分析3种最不利荷载组合时墩身应力。结果表明,即使按墩顶的4个纵向活动支座临时连接被同时破坏的最不利情况考虑,墩身在3种最不利工况下的最大主拉应力也仅为0.08 MPa,远未达到C30混凝土的拉应力容许值0.73 MPa。因此,架梁完成后未及时拆除支座临时连接的限位螺栓并不是导致该桥墩身开裂的主要原因,事故调查需从其他方面入手。但该疏忽会在桥墩中引起拉应力,应尽量避免,确保桥梁建造的各个环节更为规范。