大跨预应力混凝土空心板的振颤及防范

由于高强钢铰线预应力混凝土空心板厚度减少 ,刚度降低 ,自振频率降低 ,在室内各种振动荷载作用下虽然强度和挠度满足要求 ,但有时使用者会感到不舒适。基于加拿大国家建筑法规提出了当单块预应力混凝土空心板的基频不满足限值时应采用装配整体式方案。为保证装配整体式预应力楼盖共同工作 ,应浇筑混凝土现浇层 ,用正交异性板理论分析楼板基频。通过分析得知加设现浇层可增加楼盖的基频和刚度 ,避免振颤     

我国文化贸易在金融危机背景下的发展对策探讨

所谓文化贸易就是以文化传播为主体的贸易，是以文化产业为基础的。文化传媒包括传媒出版、旅游、影视等各个领域。正因为如此，文化贸易才具有多样性。随着经济的迅速发展，各行各业呈现欣欣向荣的景象，随着人们生活水平的提高，精神层次的追求也步入新的台阶，文化贸易因此大放异彩。尤其是在金融危机的背景下，文化贸易的发展显得更加突出。本文将主要对我国文化贸易的现状进行分析，就如何在金融危机的背景下促进文化贸易的发展进行探讨。     

聚苯乙烯改性烷氧羰基硫脲螯合树脂对Cu(Ⅱ)的吸附性能

采用静态吸附法考察了吸附时间、吸附温度、Cu(Ⅱ)初始浓度和溶液酸度对聚苯乙烯改性烷氧羰基硫脲螯合树脂(PSATU)吸附Cu(Ⅱ)性能的影响,树脂对Cu(Ⅱ)的饱和吸附容量为0.431mmol/g.PSATU树脂吸附过程符合Boyd液膜扩散方程和Langmuir等温吸附模型.吸附过程焓变和熵变大于零,吉布斯自由能变化值小于零,吸附过程为吸热的自发过程.PSATU树脂吸附Cu(Ⅱ)后,C=O、C=S和N-H键的吸收峰发生了变化,表明吸附过程中Cu与相应官能团发生了配位.     

提高化工工艺学教学质量的几点探索

针对化工工艺学教学中存在的普性问题,从课程本身的内容和特性出发,采用归纳性、创新性、理论性、前沿性教学方法,增加教学的知识性、趣味性、连贯性,提高学生的使命感和认知感,增进了教学效果,提高了教学质量.     

酰氯的合成方法及其应用新进展

以羧酸和酰化试剂为原料进行反应,是现今合成酰氯的主要方法。根据酰化试剂的不同,系统地介绍了三氯化磷法、五氯化磷法、氯化亚砜法、光气法、固体光气法和四氯化碳法。同时对酰氯作为中间体在医药、农药、资源环境等方面的研究和应用进行了相应的介绍和展望。     

Effect of N-substituents on performance of thiourea collectors by density functional theory calculations

Using density functional methods, some properties were studied such as the energies and compositions of frontier molecular orbitals and the atomic charges, which are related to the reactive behavior of thioureas containing different N-substituent groupings. The calculation results indicate that the N-substituent groupings have significant effect on the flotation performance of thiourea collectors. The order of electron-donating ability is N-propyl-N′-benzyl-thiourea (PBZYTU)＞N-propyl-N′-ethyl-thiourea (PETU) ＞N-propyl-N′-allyl-thiourea (PALTU)＞＞ N-propyl-N′-acetyl-thiourea (PACTU) ＞N-propyl-N′-ethoxycarbonyl- thiourea (PECTU) ＞N-propyl-N′-benzoyl-thiourea (PBZOYTU), and the order of feedback-electron-accepting ability is PBZOYTU＞PACTU＞PECTU＞＞ PALTU＞PETU＞PBZYTU. This implies that PBZOYTU, PACTU or PECTU can react with copper atoms having (t2g)6(eg)3Cu(II) or t6e4Cu(I) configuration on the surfaces of copper sulfide minerals through normal covalent bond and back donation covalent bond, and exhibit excellently collecting performance for copper sulfide minerals. These are consistent with the experimental data reported in the literatures.     

Flotation of aluminosilicate minerals using alkylguanidine collectors

The flotation mechanism of aluminosilicate minerals using alkylguanidine collectors was studied through flotation experiments, Zeta potential measurements and FT-IR spectrum analysis. It is shown that kaolinite, illite and pyrophyllite all exhibit good floatability with alkylguanidines as collectors at pH 4-12. The flotation recoveries rise with the increase of the carbon chain length. Isoelectric point(IEP) is determined to be 3.5, 3.0 and 2.3 for kaolinite, illite and pyrophyllite, respectively. However, it is anomalous that the presence of cationic collectors has less influence on the negatively charged mineral surfaces. It is explained by the special structure of guanidine which is one of the strongest bases, having two -NH2 groups. One of them maybe interacts with minerals by electrostatic forces, and the other maybe forms hydrogen bonding with OH- ions on the aluminosilicate surfaces or in the aqueous solution, increasing the density of negative charge on the aluminosilicate surface and leading unpronounced positive charge to increase on the aluminosilicate. By combining the flotation tests, Zeta potential and FTIR measurements above, the interaction mechanism can be concluded. The simultaneous presence of cationic and neutral amine groups makes it possible for SAG cation to bind on three aluminosilicate minerals by both electrostatic attraction and hydrogen bonding. While in acidic medium, the interaction of the alkylguanidines on the aluminosilicate surfaces is mainly by means of electrostatic force and hydrogen bond; in the alkaline medium, it is by the way of electrostatic effect and hydrogen bond.     

低碱度铜硫分离高效抑制剂的研究

对有机抑制剂DP-1、无机抑制剂DP-2和DP-3浮选分离德兴铜矿一段铜硫混合精矿进行了试验研究。结果表明,DP-1、DP-2和DP-3都是铜硫分离时硫的有效抑制剂,但DP-3的综合性能要优于DP-1和DP-2抑制剂。闭路浮选试验结果表明,当DP-3总用量为500g/t时,可获得铜精矿中铜品位28.43%、铜回收率97.71%和钼品位0.212%、钼回收率80.56%的二段分离指标,与石灰工艺相比,铜、钼、金、银的回收率分别提高了0.75%、31.38%、2.76%和8.31%,表明低碱度浮选工艺对于伴生金属的回收具有十分明显的优势。生产综合样验证试验进一步证明捕收剂Mac-12和抑制剂DP-3可望实现德兴铜矿铜硫低碱度高效浮选分离。     

九十年代铝土矿选矿除杂研究现状与展望

概述90年代铝土矿选矿除杂的研究现状，对已存在的除杂方法进行简明系统的综述，并对铝土矿选矿的发展趋势作了探讨。     

中碱度条件下乙氧羰基硫脲浮选分离铜硫

对乙氧羰基硫脲和丁黄药组合捕收剂方案浮选德兴铜矿进行了小型和工业试验研究.结果表明,与丁黄药单一捕收剂方案相比,组合捕收剂方案可使石灰用量降低2/3,实现铜铁混合精矿在pH值为10.5左右的高效浮选分离,显著提高矿山铜、金和钼的回收率.采用普遍化微扰理论和密度泛函B3PW91/6-31G(D)计算对上述实验结果进行了理论分析.ECTU的反应中心为硫代羰基中的硫原子,ECTU的最高占据分子轨道与次最高占据分子轨道的能量接近,主要由硫代羰基中的硫原子组成.ECTU的最低未占据分子轨道由官能团-O-C(=O)-N-C(=S)-N-中各原子的pz轨道组成,为一大π键,具有强烈接受和分散电子对的能力.ECTU易与表面电子组态为(t2g)6(eg)3Cu(Ⅱ)或t6e4 Cu(Ⅰ)的硫化铜矿物形成正配键和反馈键,而难与表面电子组态为(t2gа)3(egа)2 Fe(Ⅲ)或(t2g)6Fe(Ⅱ)的硫化铁矿物作用.UV和FTIR光谱结果进一步证实了ECTU对铜矿物具有优异的捕收能力,对硫矿物具有较好的选择性.