PRECIPITATING KINETICS OF V(C, N) IN FERRITE OF V–N MICROALLOYING STEEL

V--N微合金钢的C含量(质量分数)在0.05%---0.30%范围内变化时, V(C, N)在铁素体中析出开始时间随温度降低单调增加. 实验得到的开始析出点是在750 ℃时的10 s左右, 含C量不同的4种钢得到的形核率--温度 (NrT)曲线 和析出--温度--时间 (PTT) 曲线单调变化的趋势相同. 热力学与动力学计算得到的不同C含量钢中的V(C, N)形核驱动力非常接近, 其NrT和PTT曲线随C含量无明显变化. 实验与计算均证实, 实验钢的C含量在0.05%---0.30%范围内变化时, V(C, N)在铁素体中的析出动力学无明显差异.     

等通道热挤压变形对奥氏体不锈钢组织与性能的影响

在500℃～1000℃温度区间,对00Cr19Ni10奥氏体不锈钢进行了ECAP热挤压变形,利用金相显微镜与透射电镜对变形后的组织进行了微观组织观察。发现ECAP变形的组织演变过程与孪晶带和剪切变形带的形成及演变有关,同时发现随着变形温度的升高,组织逐渐从以孪生变形为主向以滑移带变形为主转变。对变形后金属的力学性能进行了测定。结果表明,等通道热挤压变形能显著提高材料的综合力学性能。     

自动管端除渣机的设计与应用

随着螺旋缝钢管生产工艺的不断完善,管端扩径技术得到广泛的推广应用,该工艺要求距管端250 mm范围内清洁无杂物。通过自动管端除渣机的设计与应用,解决人工除渣存在的诸多问题,保证了管端扩径工序的顺利进行。     

断夜处理天数对延迟甘蔗开花的影响

对早花甘蔗亲本进行同一光照强度不同持续天数的断夜处理,研究断夜天数对甘蔗开花的影响和不同品系对断夜天数反应的差异.参试品种在8月下旬至9月中旬间断夜15天和26天处理的开花高峰期分别比自然光照处理的延迟20天和30天左右,增加断夜天数对推迟甘蔗始花期和降低抽穗率有明显的影响,但不同品系对断夜天数的反应,特别是在开花持续期和终花期方面,存在较大的差异.在实际应用中,宜根据不同品系的特性确定适宜的断夜处理天数.     

稳定图方法在随机子空间识别模态参数中的应用

参数识别是结构健康监测领域研究中的重点。随机子空间法是近年来发展起来的一种线性系统辩识方法,可以有效地从环境激励的结构响应中获取模态参数。在随机子空间识别方法中,确定系统的阶数是该方法的关键工作。稳定图方法是一种比较新颖的确定系统阶次的方法,但该方法容易识别出虚假模态。针对这种情况对稳定图方法进行了改进,避免了虚假模态的出现,进而提高了随机子空间方法的识别精度。稳定图方法改进的重点是用模态置信因子来消除虚假模态。同时由于通常采用的阻尼理论与实际情况尚存在差距,影响了识别效果。在稳定图中将阻尼比的标准放松或取消,得到更加理想的识别效果。最后对此方法在一三跨连续梁的数值模型上进行了验证,结果表明,该方法具有良好的识别效果。     

A Study of the Heat Transfer Characteristics of an FC-72(C6F14) Two-Phase Closed Thermosyphon with Helical Grooves on the Inner Surface

This study is a fundamental work performed to obtain basic information about designing two-phase closed thermosyphons with a working fluid of FC-72 (C₆F₁₄). FC-72 is a kind of alternative refrigerant designed to be chemically safe and more environmentally friendly than any other conventional CFC refrigerants.

To obtain experimental data on operational performances of a FC-72 two-phase closed thermosyphon, an experimental model was designed and manufactured with a micro fin groove copper tube with an outside diameter of 22.2 mm for its container, on which a series of operational performance tests were conducted. Its maximum capacity of heat transport rate was designed to be about 300–400 W. The focus was given to investigate the effects of such parameters as micro fin grooves and fill charge ratios on operational performances of the FC-72 two-phase closed thermosyphon. The experimental data on phase change heat transfer coefficients and heat transport limitations were compared with some corresponding correlations, and a couple of measures that would help to predict operational performances were suggested with some physical explanations.     

磁性树脂的制备及其性能的应用进展

磁性树脂作为环境友好型功能性吸附材料,在水体系处理、环境修复、催化技术等领域是研究热点。携带不同功能基团与种类各异的磁性树脂对污染物展现出不同程度的去除能效。本文章阐述了磁性树脂性能的增效机制主要包括协同作用、吸附作用及再生作用,重点综述了磁性树脂的制备技术及其性能的应用进展,并结合磁性树脂已有的制备技术与实际应用现状,对其研究存在的问题及未来的研究方向进行简要的展望。     

INHIBITORY EFFECT OF ANTHOCYANIN EXTRACT FROM SEED COAT OF BLACK BEAN ON PERICARP BROWNING AND LIPID PEROXIDATION OF LITCHI FRUIT DURING STORAGE

ABSTRACT

Anthocyanins were extracted from seed coats of black beans (Glycine max[L.]) and the inhibitory effects of anthocyanin extract on pericarp browning and lipid peroxidation of litchi fruit were investigated. Litchi fruit were infiltrated for 3 min with 0 (control) or 50 mg/L of anthocyanin extract at a reduced pressure of 53 kPa, then packed in 0.03 mm thick polyethylene bags, and finally stored at 28C for 6 days. Changes in browning index, contents of anthocyanins and total phenol, peroxidase (POD) activity, levels of relative leakage rate and lipid peroxidation, α,α‐diphenyl‐β‐picrylhydrazy (DPPH) radical scavenging activity and reducing power were evaluated. Application of anthocyanin extract from black bean delayed pericarp browning of litchi fruit during storage, which was associated with reduced POD activity and higher contents of anthocyanins and total phenol. Moreover, the anthocyanin extract was found to have a direct inhibition on the POD activity in vitro. Furthermore, application of the anthocyanin extract apparently reduced lipid peroxidation and relatively maintained membrane integrity, which may account for browning inhibition to an extent. Finally, higher DPPH radical scavenging activity and reducing power of the fruits treated with the anthocyanin extract than control fruits possibly benefited in scavenging free radicals and reducing lipid peroxidation. It is, therefore, suggested that inhibited POD activity and reduced lipid peroxidation by the anthocyanin extract from seed coats of black beans were responsible for the inhibition of pericarp browning of litchi fruits.

PRACTICAL APPLICATIONS

Lipid peroxidation is a major cause of quality deterioration of postharvest fruits and vegetables. Some synthetic antioxidants are beneficial in inhibiting lipid peroxidation. However, considering that synthetic antioxidants, such as butylhydroxyanisole and butylated hydroxytoluene (BHT), have potential toxicity, the use of natural extracts to extend the shelf life of postharvest fruits and vegetables is a tendency. In our previous study, it has been found that anthocyanin extract from litchi pericarp has stronger antioxidant activities or free radical scavenging activities than BHT and ascorbic acid ( Duan et al. 2007 ). In this study, the application of anthocyanin extract from seed coat of black soybean showed reduced lipid peroxidation and pericarp browning. It could be used potentially as a postharvest technology for reducing or replacing the use of other chemicals, but it requires further investigation.     

即食马蹄软罐头关键加工工艺优化

以新鲜马蹄为原料,采用感官评分和白度值为考察指标,研究不同蒸煮时间、护色剂和杀菌条件等关键工艺对马蹄软罐头品质的影响。研究表明,即食马蹄软罐头最佳加工工艺条件为蒸制时间7 min、护色时间25 min、复合护色剂为柠檬酸0.5%、氯化钠0.9%、抗坏血酸0.20%,115 ℃灭菌8 min 时,马蹄软罐头白度值达到69.78,感官评分为90.50,通过对比试验得出此时马蹄软罐头产品品质最佳,灭菌时间和温度明显降低,达到商业无菌标准,符合食品卫生要求。产品色泽洁白、口感清脆爽口、硬度适中,具有浓郁的马蹄风味。     

米糠蛋白改善大鼠脂质代谢作用及机制研究

为了讨论米糠蛋白对高脂饮食状态大鼠脂质代谢的影响及作用机制。试验设计酪蛋白组（CAS,对照组）、米糠蛋白组（RBP）、糙米蛋白组（BRP）和大米蛋白组（WRP）等4组,饲喂大鼠分别添加了质量分数20%酪蛋白、15%酪蛋白+5%米糠蛋白、15%酪蛋白+5%糙米蛋白和15%酪蛋白+5%大米蛋白的高胆固醇饲料3周。实验测定大鼠血清总胆固醇（TC）水平、甘油三酯（TG）浓度以及肝脏TC、TG和总脂质的含量,并收集了实验后期3 d的粪便,测定其总胆汁酸和中性固醇的排泄量。采用体外模拟人体胃肠消化道环境试验,测定CAS、RBP、BRP及WRP对胶束溶解度的抑制率和不同浓度RBP的胆汁酸结合能力。结果显示,高纯度米糠蛋白与酪蛋白和其他蛋白组相比较能明显降低高胆固醇饲喂大鼠的血清TC（P<0.05）以及动脉粥样硬化指数（P<0.05）,肝脏TC水平显著降低（P<0.05）,粪便中总胆汁酸排泄量显著增加（P<0.05）。体外实验结果表明,米糠蛋白能与胆汁酸相结合,显著抑制了胆固醇胶束溶解度（P<0.05）。综上所述,米糠蛋白在体内与胆汁酸相结合,抑制其在肠道的吸收,增加其粪便中的排泄量,最后达到降血脂的作用。