木质纤维制乙醇关键设备结构研究

螺杆挤压技术用于处理木质纤维植物可实现连续化蒸爆.通过分析螺杆挤压膨化机的结构和工艺过程可知,螺杆挤压膨化机可作为木质纤维原料制作乙醇工艺生产中预处理工序中的一台关键设备.     

The A9 Core Sequence from NRPS Adenylation Domain Is Relevant for Thioester Formation

The adenylation (A) domain in nonribosomal peptide synthetases catalyses a two-step reaction in which an amino acid is activated and then transferred to the neighbouring thiolation (T) domain. In this study, we investigated the role of the conserved A9 core sequence of the A-domain of tyrocidine synthetase 1, by analysis of single amino acid mutations in the A9 region. Mutation of an absolutely conserved proline (P490G) significantly reduced the conformational stability of the protein, as evidenced by increased susceptibility to proteolytic cleavage and denaturation. All mutant A-domains were capable of amino acid activation, but the activity in the overall reaction was reduced. Surprisingly, the S491R mutant (mutation at the first residue following the A9 motif) showed elevated overall activity compared to the wild-type protein. Our results suggest that the A9 core sequence plays a role in the second reaction step, in which it could serve as a "clip" for the proper positioning of residues important for the interaction with the T-domain, and/or stabilisation of the thioester-forming conformation.     

改善釉浆触变性的途径

泥浆在静置以后变稠和凝固,但一经搅拌或插动立即恢复原先的流动状态,这种特性称为触变性。也就是说,这种材料在剪应力保持一定时,表观粘度将随剪应力作用的持续时间而减少,剪应变速率不断增加。泥浆触变性产生的原因是片状高岭土微粒在层面上带负电,而边棱上因断键而带正电。在静置时,颗粒间可通过棱和面结合成空间架状结构,其空隙体积很大,可以填入大量水分使泥浆流动性降低,呈现凝固状态。但经外光搅拌,架状结构破坏,原先填充在空隙中的水分转为自由水,使流动性增加,呈溶胶状态。因此,要降低釉浆的触变性,需从破坏其架状结构入手。     

Creating a high-quality wool-oriented Turkish merino herd and investigation of mechanical and dyeability properties of fabrics produced from Turkish merino in comparison with Australian merino

Today, the need for quality wool suitable for worsted fabric production in the world is mainly met by Australian merino wool. In Turkey, which has a significant sheep population, in addition to domestic breeds, approximately 10% of the total sheep population (around four million head) is composed of merino cross breeds. However, the fleece quality is far from meeting Australian merino wool standards. Therefore, the aim of this study is to ensure a merino herd with high-quality wool in Turkey. For this aim, by carrying out field studies in the Thrace region of Turkey where Turkish Merino sheep are widely bred, sheep with fleece that can meet the demands of the worsted industry were determined. As a result of field studies in which thousands of sheep were examined, it was determined that 43 female and 10 male sheep had fleece that would meet these standards. Then the breeders of the sheep, which had quality fleece, were persuaded and these sheep were purchased, and “Turkey's wool-oriented Turkish (Karacabey) Merino Herd” consisting of 30 sheep and three rams was formed in the farm of Tekirdağ Namık Kemal University. In the second part of this study, a 100% wool fabric produced by using Australian merino was taken as a reference and it was aimed to produce the same fabric from Turkish merino wool. For this aim, the wool-oriented Turkish Merino herd, which was bred at the university farm for 1 year, was shorn in May 2022. Then, Turkish and Australian merino wools were first converted into worsted yarn and then into woven fabric. The results of mechanical (tensile strength, pilling, abrasion resistance, felting shrinkage, Hofmann dimensional change, bending stiffness) and dyeability (dye-uptake, CIE L*a*b* and colour yield (K/S) values; washing, rubbing and light fastness values) properties of fabrics produced from Turkish and Australian merino wool is presented.     

催化蒸馏选择加氢的数学模型和模拟

在SHBWR汽液平衡方程、幂函数型动力学方程的基础上，假定每个催化床层为－全混流反应器，建立了碳三催化蒸馏选择加氢数学模型，利用二阶P－K算法进行收敛计算。提出了给反应速率方程添加收敛引子，结合“向上逐层累加”法使模型收敛的方案。     

混合脱水系统爆炸的原因及预防措施

根据氯碱厂生产实际,详细分析了混合脱水系统爆炸的原因,并提出了预防措 施。     

C60精氨酸铅盐的制备及表征

以C60和精氨酸为原料经亲核加成反应合成得到C60精氨酸,C60精氨酸再与硝酸铅反应得一种C60金属盐衍生物—C60精氨酸铅盐。同时采用傅里叶变换红外光谱(FTIR)、质谱(MS)、紫外可见光谱(UV-Vis)、原子吸收(AAS)、X射线衍射(XRD)、X射线光电子能谱(XPS)以及元素分析等测试手段对产物结构进行了表征。采用热重分析法对其失重情况进行了研究,失重率为57.86%,采用差热分析法对C60精氨酸铅盐的热稳定性进行了研究,结果表明,在空气气氛下,DSC分解峰值温度为285、435℃;目标产物表现出良好的热稳定性。     

世纪之争—全液压式与全电动式注塑机的比较

就全液压式与全电动式注塑机的锁模系统、注射系统和整机性能的优缺点进行了比较,阐述了作者自己的观点：全电动式注塑机将主要用于中小型注射成型机生产高档精密和小型精密零件,而不同类型的全液压式注塑机用于中高档、高档精密和特别高档制品的成型;大型注塑机应开发复合两板式注塑机。     

Synthesis and chain flexibility of poly(cyclohexylethyl methacrylate)

The synthesis and characterization of fractions of poly(cyclohexylethyl methacrylate) (PCHEM) are reported. A combination of low-angle laser light scattering and intrinsic viscosity experiments was employed to estimate the characteristic ratio (C_∞) of this polymer. The value of 10.7 obtained for PCHEM is similar to the value of 11.3 found previously for poly(phenylethyl methacrylate) but is smaller than values measured for poly(cyclohexyl methacrylate) and poly(cyclohexylmethyl methacrylate) (C_∞ = 11.6 and 11.9, respectively). Received: 28 October 1996/Revised: 16 December 1996/Accepted: 19 December 1996     

8-氟-5-甲氧基-1,2,4-三唑并[4,3-c]嘧啶-3(2H)-硫酮的合成

以5-氟尿嘧啶为起始原料,经氯代反应、醇解反应、肼解反应和环合反应合成了高效除草剂双氟磺草胺的关键中间体—8-氟-5-甲氧基-1,2,4-三唑并[4,3-c]嘧啶-3(2H)-硫酮。以5-氟尿嘧啶计,产品总收率达70.1%,产品结构经核磁共振分析验证。探讨了原料配比、反应温度、时间等因素对反应收率的影响。