浅谈pH中和剂对悬浮聚合反应体系的影响

在氯乙烯悬浮聚合体系中,随着聚合反应的进行,反应体系的pH值会随着反应的进行而降低,而pH值过低对反应体系不利,不仅影响村脂颗粒结构,而且严重时造成爆聚,因此会在悬浮聚合反应过程中加入pH中和剂(即缓冲剂)来调节体系的pH值,而加入量的多少将直接决定着反应体系的稳定性及生产成本,本文就根据我公司近年来聚合pH值缓冲剂的使用进行浅显的探讨.     

化工企业生产MMA高有机物及高氰化物的废水处理

为提升MMA高有机物及高氰化物废水处理效果,文章设计一种化工企业生产MMA高有机物及高氰化物的废水处理技术。将MMA废水分为预处理与生化处理两个部分：在预处理阶段处理氰化物与有机物,调节废水的pH值,使其达到出水标准;在生化处理阶段,利用硝化液处理NH₃-N、氰化物,处理废水中的COD等污染物质。通过控制pH值、铁碳质量比,实现COD的高效处理。使用臭氧催化氧化技术之后,COD由26 000 mg/L变化到150 mg/L;NH₃-N由150mg/L变化到了5mg/L;氰化物含量或可忽略不计;pH值从2.5增加到了6.8,废水处理效果较佳。得到结论为臭氧催化氧化技术在MMA高有机物及高氰化物废水处理中具有重要作用,能够满足化工企业生产需求。     

影响己内酰胺废水处理效果的因素及控制措施

通过对己内酰胺生产废水治理操作中出现的问题进行分析,总结出影响延时序批式生物氧化硝化反应器(ENSBR)对该种废水处理效果的主要因素是pH值、氨氮污泥负荷、水质突变等,并提出及时监测水质、掌握运行状态、正确调整操作等控制措施。     

酶型时间温度指示器研究应用分析

酶型时间温度指示器(TTI)通常利用酶和底物水解致使pH值发生改变,配合pH指示剂,产生可见的颜色变化;或者是酶直接催化底物发生有颜色变化的反应,从而实现对食品品质变化的检测。酶型TTI具有稳定性强、成本较低以及易于控制等优点,已成为时间温度指示器研究领域的焦点。本文对目前研究与应用领域的酶型TTI进行了分类探讨与展望。     

温度对活性污泥硝化反应的影响

温度是影响活性污泥法污水处理厂生物脱氮效果的重要因素。文章中实验采用1套SBR反应器小试装置,接种某城市污水厂曝气池好氧活性污泥,采用16S rDNA高通量测序技术,对活性污泥的菌群进行了检测,并以人工配水为进水,进行了1℃、5℃、8℃、11℃、17℃、19℃、21℃不同水温对活性污泥硝化反应影响进行实验。结果表明：污泥中存在Nitrosomonas(亚硝化单胞菌属)和Nitrospira(硝化螺菌属),相对丰度分别为0.074%和0.341%。21℃时硝化反应速率最大,达到4.3 mgNO₃-N/(gMLVSS·h);随着水温的降低,硝化反应速率下降,1℃时硝化反应速率仅为0.3 mgNO₃-N/(gMLVSS·h)。研究成果可为低温地区污水处理厂的优化运行,提高脱氮效果提供理论依据。     

一株反硝化细菌在尾水中的脱氮性能研究

为了提高城市尾水中氮的去除率,优化筛选出一株好氧同步硝化-反硝化细菌,通过调整尾水的氨氮浓度,研究其在不同氨氮浓度的尾水中的反硝化能力。结果表明:好氧同步硝化-反硝化细菌FX7h的硝化和反硝化能力较强,在24,48h硝态氮降解率分别达到83.1%和91.1%;在氨氮质量浓度为10mg/L的城市尾水中,总氮、氨氮、硝态氮去除效果最明显,去除率分别为56.9%,70.2%,91.1%;亚硝态氮出现累积,累积率为20%;氨氮质量浓度为15,25mg/L条件下,总氮与氨氮去除效果明显降低;在25mg/L条件下,亚硝态去除率增加,硝态氮去除率不明显。因此,好氧同步硝化-反硝化细菌FX7h在氨氮质量浓度为10mg/L的城市尾水中进行异养硝化和好氧反硝化作用的效果最好,其在实验过程中以去除氨态氮为主。所采用的细菌脱氮方法与传统的生物脱氮相比具有节约运行成本、耐氧性好、平衡pH值等优势,有着广阔的应用前景。     

硫酸法钛白粉还原过程及机理研究

研究了硫酸法钛白粉的还原反应过程,并考察了还原剂添加量、反应温度、反应浓度以及反应体系pH值几种影响因素对硫酸法钛白粉制备还原反应的影响。结果表明,当还原剂添加量至0.20%时,还原反应最佳;反应物浓度对反应速度影响较小,在120g/L-160g/L达到还原反应较为彻底基本已趋于稳定;反应温度太低太高均不利于还原反应的进行,在55°C时反应最佳;强酸性条件有益于还原反应的进行,当pH值小于2时还原反应速率明显较快。基于硫酸法钛白粉还原过程中Fe3+还原成Fe2+,探讨了还原过程的反应机理。     

纳米零价铁的制备及其去除水中重金属离子的研究

文章介绍了通过热还原法,利用茶多酚和Fe(NO_4)_3·9H_2O还原反应制备纳米级的零价铁颗粒。用茶多酚为还原剂可直接取材于茶叶,研磨完毕即可作为原料进行反应。生成的纳米级的零价铁具有良好的去除水中重金属离子的能力,其零价铁能还原水中的重金属离子,且为纳米级,能吸附被还原的金属,使其对重金属的去除更加有效快速。此类纳米零价铁催化剂以后有望普及于各类净水剂中。通过实验,找到了适宜的反应条件,制备了纳米零价铁,并使其与水中常见的重金属离子Cr~(6+)进行反应,监测反应过程中溶液的pH变化。在不同的pH值下考察纳米零价铁对重金属离子的去除效果,并得到室温下纳米零价铁最适宜与重金属离子反应的pH值范围,便于以后应用时作为重要的参考数据。     

pH值对罗布麻生物脱胶的影响

pH值对酶促反应的进行有着十分重要的影响在罗布麻生物脱胶过程中，由于麻皮中的溶出物，细菌的生长繁殖以及胶质的分解产物会使培养基pH值有较大幅度的下降对此必须加以调节。本文通过实验证明在浴比为1：25时培养基中加入K2HPO4.3H 200.6g，初始pH值为9.1可获得较好的脱胶效果，并且使用弱碱K2HPO4.3H 2O比强碱NaOH调节pH值所得的脱胶效果要好的多。     

2-吡啶甲酸铬的工艺改进

以2-氰基吡啶为原料,经水解、中和、络合反应得到2-吡啶甲酸铬。通过对反应溶剂、络合pH值、络合温度进行改进,解决了2-吡啶甲酸铬晶体细小、流动性差等问题。水解反应使用乙醇溶解2-氰基吡啶,加入NaOH水溶液进行水解,使反应在均相中进行,反应时间由10h缩短为1.5h。水解完毕调节pH值为8.9,易于络合反应的进行。络合温度控制在(50±2)℃,利于晶体的增长。按此工艺制得的2-吡啶甲酸铬纯度为99.8%,单杂0.04%,总杂0.12%,晶体颗粒均匀,流动性好,休止角为31°,更易于制剂过程中混合均匀。     

The impact of new product launch strategies on competitive reaction in industrial markets

The importance of successful innovation for the long‐term performance of companies can hardly be exaggerated. However, we need to consider this in a dynamic setting, in which competitors do not remain passive. We find that two thirds of new product launches meet reaction by competitors after their launch. We also empirically demonstrate that the strategic launch decisions that managers take have an effect on future reaction by competitors. Following an extensive review of the literature, a propositional model is developed. In order to test this theoretical model, an ex post facto field study was designed, in which the authors obtained comprehensive information on 509 new industrial products launched in the US, the UK and the Netherlands. Competitive reaction is diagnosed in terms of changes in the marketing instruments of the competitor. A logistic regression model is estimated on the occurrence of competitive reaction with any marketing instrument. We also look at the occurrence of individual marketing instrument reactions. The data show that competitors react primarily by means of price changes. Product assortment and promotional changes are less frequent, whereas distribution policy modifications occur very rarely. The characteristics of the new product launch strategy were found to have a significant impact on both the occurrence and nature of competitive reactions. We claim that the competitive effect of radically new products and incrementally new products greatly differs. The results show that competitors fail to respond to radical innovations and to new products that employ a niche strategy. They do react if a new product can be assessed within an existing product category and thus represent an unambiguous attack. Both innovative and imitative new products meet reaction in this case. The results also demonstrate that competitors are more inclined to react to the introduction of new products that are supported by extensive communication by the innovating firm. The likelihood of reaction is also higher in high growth markets than in low growth markets. The article discusses theoretical and managerial implications of these results, as well as thoughts for future research that may add more insight.     

手性催化剂脯氨酸在不对称合成中的应用进展

针对脯氨酸作为一种结构简单而且含量丰富的小分子手性催化剂在多种不对称催化反应中表现出的非常好的催化性能,综述了近年来脯氨酸在Aldol反应、Mannich反应、Michael反应及其他不对称合成反应中的应用,展望了脯氨酸的应用前景。     

有机小分子催化的不对称直接Aldol反应研究新进展

对近些年来L脯氨酸(LProline)等6类有机小分子催化剂催化不对称直接Aldol反应的特点、实用范围及结果作了详细介绍,认为该领域具有广阔的发展前景。     

A Conjoint-based Product Designing Procedure Incorporating Price Competition

Conjoint analysis has become a major tool in the process of designing and concept testing consumer packaged goods and industrial products. In most applications, however, product concepts are tested against existing sets of competing brands without considering potential competitive reactions. Although many researchers have recognized the need for models to incorporate competitive reactions, few methodological developments have been published thus far. Instead of what-if analysis, which depends heavily on the managers' intuition about the competitors' reactions, S. Chan Choi and Wayne DeSarbo propose a game theoretic approach that models competing firms' reactions in price. This price reaction model is incorporated in the conjoint simulator for evaluating product concepts against competing brands. They illustrate the methodology using a commercial data set previously collected.     

β-D-半乳糖苷酶活性测定方法的研究

应用分光光度计建立一种简便检测β D 半乳糖苷酶(GAL)活性的方法。酶反应条件研究表明,在总体积为1mL的0.1mol/L柠檬酸反应缓冲体系(pH值为4.5)中含0.8μmol的底物邻硝基苯β D 吡喃半乳糖(ONPG),含相当于2mg左右蛋白质的酶提取液,37℃孵育30min后用0.5mol/L碳酸钠1mL终止反应,用紫外分光光度计于405nm波长测定的吸光度值最能反映该酶活性。结果显示,该方法的批内变异系数在3.92%～4.89%之间,批间变异系数为3.8%,均小于5%;在所检测该酶质量浓度范围(1～2.5mg/mL)内线性关系良好,当反应体系的蛋白含量低于0.5mg/mL时,酶活性不能被检出;每组的平均回收率均在95%～105%之间,说明在所检测浓度范围内回收良好。因此,该方法具有稳定性好、灵敏度高、简便易行等特点,适合一般实验室应用。     

纯棉针织物果胶酶精练工艺优化及效果分析

利用KDN果胶酶,采用田口实验设计的方法,控制酶浓度、温度、pH值和时间,分别处理纯棉纬编针织物,通过测试处理后织物的白度、毛细效应、顶破强力、质量损失等性能,分析果胶酶处理织物的效果。结果表明纯棉纬编针织物经果胶酶处理后毛细效应得到很大改善,白度增加,但织物顶破强力下降,质量减轻。综合各项指标,通过统计分析得出KDN果胶酶最优处理工艺如下:酶质量浓度1.5g/L,温度50℃,pH值为6,时间40min。与碱精练相比,毛细效应变好,白度稍差,织物强力及质量损失小。     

What's in a name.com?: The effects of ‘.com’ name changes on stock prices and trading activity

This paper uses a market signaling perspective to examine investor reactions to firm announcements of name changes to include ‘.com.’ Firms that change their name as a purely cosmetic technique are contrasted to those that employ other strategic investments. Results show that announcements of ‘.com’ name changes are associated with significant increases in stock prices and trading activity. Furthermore, the magnitude of investor reactions is significantly larger when name changes are accompanied by other strategies. Copyright © 2001 John Wiley & Sons, Ltd.     

甲萘酚代替萘乙二胺测定水中苯胺类化合物

在 p H为 1 2的硼砂 -氢氧化钠缓冲液中苯胺类化合物的重氮盐与甲萘酚的显色反应迅速 ,显色液可稳定 2 h以上。用甲萘酚代替萘乙二胺测定苯胺类化合物 ,简便 ,快速 ,稳定。苯胺类化合物的质量浓度在 0 .0 3～ 2 .8mg/L范围内符合比尔定律 ,线性相关系数为 0 .9999。该法与废水中苯胺类化合物标准测定方法相比结果一致     

New product announcements as market signals: A content analysis in the DRAM chip industry

New-product announcements (NPAs) have considerable effects on competitors in industrial markets. Several studies have shown that the perceived threat caused by an NPA may trigger severe competitive reactions. Yet, it is still unclear how the perception of threat by competitors is related to the specific content of the announcement.This study explores the actual content of NPAs observed in a particular market. This is done through a multi-year content analysis of new-product announcements in the DRAM memory chip industry. The study analyzes patterns in the occurrence of attributes and demonstrates how firm strategy affects NPA content. Findings from this study provide important insights for managers about the design of NPAs. It also triggers further research on the use of NPAs in competitive industrial markets.     

Political reforms,rural crises,and land tenure in western Europe

This paper analyzes the origins and causes of the differences and changes in land tenure institutions over more than a century in several western European countries. The analysis shows that differences and changes in land tenure are caused by a combination of economic, institutional, and political factors, including the French Revolution, changes in agricultural profitability, voting rights reforms, etc. Significant changes in land tenure regulations resulted from the combination of both improved political representation of tenants in parliament and a severe economic crisis increasing the pressure for reforms. Empowerment of small tenants and farm workers and increasing their access to and influence on policy-making appears to be an important pre-condition in order to improve their land tenure rights.