New intramolecular effect observed for polyesters: An anomeric effect

A series of polyesters was prepared to evaluate hydrolytic stability as a function of cyclohexyl dibasic acid content. The three cyclohexyl dibasic acids: 1,2; 1,3; and 1,4 were formulated into polyesters with two glycols. The proportion of cis and trans isomers was evaluated via ¹H NMR. The hydrolytic stability of short chain polyesters was evaluated in an acetone/water mixture which solubilized the polyesters to mimic oligoester behavior within a thermosetting polyester coating environment. The rate of hydrolysis was monitored by acid titration and corroborated by GPC. Surprisingly, 1,2-cylohexyl diacid-based polyesters were robust, and 1,3-cyclohexyl diacid-based polyesters were the most susceptible to hydrolysis. Evidently, a 1,2-anchimeric effect for cyclohexyl dibasic acid polyesters was not an important consideration, while the 1,3-cyclohexyl ester interaction was. Consequently, an anomeric effect was proposed. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

Determining the life cycle of bolts using a local approach and the Dang Van criterion

The fatigue behaviour of bolts under axial load has always been considered from the component point of view for which fatigue limit is usually taken equal to 50 MPa, and few results are available to designers for limited lifetimes. Here, we take up this problem from a material point of view using a local approach. For each case of fatigue testing, using finite‐element (FE) model of the bolt, we determine the stabilized local stress at the root of the first thread in contact with the nut. To characterize bolt behaviour with these numerical results, we use Dang Van multiaxial fatigue criterion for which we extend application to the medium fatigue life. These results can be correlated with the experimental numbers of cycles to failure to determine material parameters of the generalized criterion. Using statistical Gauss method, we can make lifetime predictions for any level of risk of failure. In addition, we propose an analytical model to rapidly determine the local stress condition from nominal loading data (mean stress and alternating stress). This model dispenses us from a new modelling if the bolt is stressed in the same manner as the bolts used for behaviour characterization. Using this model and the generalized criterion, it is extremely easy to make lifetime predictions whatever the risk considered.     

镀锌钢带工艺技术改造

本介绍了将氰化钠镀锌溶液转换为氯化钾镀锌溶液的镀锌工艺过程，从工艺、健康、环保、成本等方面进行阐述。     

气体悬浮焙烧炉内衬烘炉曲线的确定

根据所使用的低水泥浇注料的性能，对中铝山西分公司检修厂4号焙烧炉制定了合理的烘烤曲线，提高了耐火内衬的质量，延长了内衬的使用寿命。     

《建设工程施工合同》中有关造价控制条款的阐析

仅从造价控制的角度分析、归纳施工合同中涉及费用的条款，以便更好地应用。     

To Do or to Have? That Is the Question.

Do experiences make people happier than material possessions? In two surveys, respondents from various demographic groups indicated that experiential purchases-those made with the primary intention of acquiring a life experience--made them happier than material purchases. In a follow-up laboratory experiment, participants experienced more positive feelings after pondering an experiential purchase than after pondering a material purchase. In another experiment, participants were more likely to anticipate that experiences would make them happier than material possessions after adopting a temporally distant, versus a temporally proximate, perspective. The discussion focuses on evidence that experiences make people happier because they are more open to positive reinterpretations, are a more meaningful part of one's identity, and contribute more to successful social relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

在备件招标采购中运用"定质比价法"初探

针对公司在备件采购中存在的质量、价格等问题，探讨了如何使用“定质比价法”这一新的招标采购方法来提高备件质量、降低成本。     

小议变动成本法的合理性

企业对盈亏临界点的计算通常是以变动成本法为基础，但也有以制造成本法为计算基础的，对于这两种成本方法计算的几种盈亏临界点的情况，本文结合案例，通过比较分析认为：盈亏临界点的计算应当以变动成本法为基础更为合理。     

浅谈工程项目的预算(成本)管理

从施工单位管理的角度出发,在工程投标、施工前、施工中及完工等不同阶段对项目的预算管理重要性进行描述,充分表明了只有加强各个阶段的预算(成本)管理,才能真正提高经济效益。     

Longitudinal analysis of the relationship between symptoms and quality of life in veterans treated for posttraumatic stress disorder.

This study examined how change in posttraumatic stress disorder (PTSD) symptoms relates to change in quality of life. The sample consisted of 325 male Vietnam veterans with chronic PTSD who participated in a randomized trial of group psychotherapy. Latent growth modeling was used to test for synchronous effects of PTSD symptom change on psychosocial and physical health-related quality of life within the same time period and lagged effects of initial PTSD symptom change on later change in quality of life. PTSD symptoms were associated with reduced quality of life before treatment. There were synchronous effects of symptom change on change in quality of life but no significant lagged effects. Results indicate the importance of measuring quality of life in future investigations of PTSD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)