自动喷水系统中防冻技术回顾与发展

如果消防管道周围温度低于0℃(如冷藏仓库、严寒隧道等),管内会出现水冻结的情况.当发生火灾时,自动喷水系统会因为无法供水而导致火灾无法及时扑灭,从而造成巨大的火灾损失.防冻措施分为防冻液技术、伴热技术和干式系统.在分析总结上述3种防冻措施前提下,提出了技术和经济评价因子,并给出了评价方法.     

大豆深加工产品中外源基因检测灵敏度的研究

为了提高大豆深加工食品中外源基因的检测灵敏度.改良了普通PCR反应的引物,并设计了NEST-PCR反应程序.模拟食品加工中高温、高压等处理方法,将转基因大豆研磨成粉状,在高压灭菌锅内进行高温、高压处理.应用新设计的引物35SCP142、CPNOSl65进行外源基因检测,通过对引物的调整,检测灵敏度得到了明显的提高,可以检测到的转基因大豆含量仅为1%.且为经过12l℃,30min处理的样品中的外源基因.应用NEST-PCR的高灵敏度的特性.设计了NEST-PCR的两对引物35SCP318和35SCP114.并检测到外源基因的片段.将普通PCR的检测灵敏度和荧光定量PCR的灵敏度作比较,若引物设计合理,且PCR条件适合,普通PCR的检测灵敏度可以和荧光定量PCR的相媲美.     

Solution‐Processable Perovskite Solar Cells toward Commercialization: Progress and Challenges

In the last few years, organometal halide perovskites (OHPs) have emerged as a promising candidate for photovoltaic (PV) applications. A certified efficiency as high as 23.7% has been achieved, which is comparable with most of the well‐established PV technologies. Their good solubility due to the ionic nature enables versatile low‐temperature solution processes, including blade coating, slot‐die coating, etc., most of which are scalable and compatible with roll‐to‐roll large‐scale manufacturing processes. The low cost, high efficiency, and facile processable features make perovskite solar cells (PSCs) a very competitive PV technology. Despite the great progress, long‐term durability concerns, toxicity issues of both materials and manufacturing process, and lack of robust high‐throughput production technology for fabricating efficient large‐area modules are major obstacles toward commercialization. In this review, the recent progress of commercially available process of PSCs is surveyed, the underlying determinants for upscaling high‐quality PSCs from hydrodynamic characteristics and crystallization thermodynamic mechanism are identified, the influence of external stress factors on stability of PSCs and intrinsic instability mechanism in OHPs themselves is revealed, and the environmental impact and sustainable development of PSC technology are analyzed. Strategies and opportunities for large‐scale production of PSCs are suggested to promote the development of PSCs toward commercialization.     

无溶剂系统微波法合成甾醇油酸酯的研究

在微波条件下,以石墨为反应加热介质,反应物油酸为溶剂,硫酸氢钠作为催化剂,植物甾醇与油酸直接酯化合成植物甾醇酯.通过单因素实验分析,筛选出微波条件下最佳反应条件为:n(油酸):n(甾醇)为4:1,催化剂用量2%,反应温度145 ℃,反应时间20 min,最佳条件下酯化率达77.42%.重结晶后产品纯度可达90%以上.     

Preparation of sodium carboxymethyl cellulose from paper sludge

BACKGROUND: This paper describes the reuse of paper sludge, an industrial solid waste, for the preparation of sodium carboxymethyl cellulose (CMC). The process includes pretreatment, basification and etherification. RESULTS: The optimal pretreatment condition involved the addition of 6.7% hydrochloric acid to the paper sludge for 30 min at 70 °C. The order of factors influencing the effect of reaction was: etherification temperature > sodium hydroxide dose > basification temperature > etherification time > sodium chloroacetate dose. The optimal preparation condition of CMC was: m_papersludge: m_{sodiumhydroxide}: m_{sodiumchloroacetate} = 0.9:0.8:1.15; basification at 40 °C; etherification at 60 °C for 1 h. Under these conditions, certified CMC with viscosity less than 20 mPa· s, DS more than 0.50 and purity more than 90% was produced. The results of Fourier transform infrared (FTIR) and X‐ray diffraction (XRD) spectra analyses indicated that the product has characteristics of high degree of substitution (DS) and low crystallinity. The coated paper using CMC prepared from paper sludge as a water retention agent can meet the quality standards of GB/T 10335.1‐2005. CONCLUSION: Preparation of CMC from paper sludge can be considered a feasible alternative, generating value‐added product and contributing to solving environmental problems resulting from paper sludge. Copyright © 2008 Society of Chemical Industry     

空调制冷系统的建模研究

在分析空调系统的作用及基本原理的基础上,从部件模型和系统模型两个方面分析和总结了国内外制冷系统的建模研究及实际应用情况,提出了将制冷系统模型与其他子系统模型相结合的方法来更好地实现空调系统功能的目标。     

Variation in limonin and nomilin content in citrus fruits of eight varieties determined by modified HPLC

Food Science and Biotechnology - The nomilin and limonin content in citrus fruits of different varieties was determined at fruit growth and maturation stages by HPLC. The results showed that the...     

一种新型热卷箱弯曲辊的标定装置

热卷箱的弯曲辊在生产中需要周期性进行辊缝位置标定,以保证弯曲辊的辊缝精度。针对1780热轧带钢生产线热卷箱区域弯曲辊辊缝标定异常情况进行分析。新设计了一种结构简单、操作方便的弯曲辊标定装置,提高了标定精度和效率,同时保证了操作人员的人身安全。     

三维激光技术在高陡危岩体调查中的应用

崩塌危岩多发育在高陡的斜坡地带,具有隐蔽性与突发性,经常造成重大人员伤亡与财产损失。因采用传统测量方法难以得到危岩体规模、负地形、不利结构面组合特征,进而判识危岩失稳模式与预测危害性,故危岩体的调查一直是地质灾害防治较为突出的难题。三维激光扫描技术通过激光反射,快速获取危高位危岩体点云特征,非接触得到所需的高陡斜坡危岩体几何与地质信息,获取传统测量无法得到的成果。本文以Optech扫描仪在高位危岩体调查中的应用为研究基础,阐述了该项技术在高陡斜坡地形图生成、节理裂隙统计、规模计算等方面的应用。并以旧关岭崩塌与南川甑子岩危岩体调查为例,诠释了激光扫描应用过程中的方法与技巧,为高陡危岩体的调查提供参考。