SBA-15固载磷钨酸催化剂的制备及催化合成叔丁基苯酚

以不同硅烷偶联剂改性的介孔分子筛SBA-15为载体、PW_(12)为催化剂,通过对SBA-15表面共价及非共价修饰制备磷钨酸@介孔分子筛/硅烷偶联剂复合催化剂PW_(12)@SBA-15/YSiX_3(YSiX_3=Apts、Atapts、Papts);并利用FT-IR、XRD、TEM、N_2吸附-脱附对其组成、结构及形貌进行表征。以改性SBA-15分子筛固载磷钨酸催化剂催化合成叔丁基苯酚为研究对象,考察不同硅烷偶联剂、反应温度、苯酚与叔丁醇物质的量比对催化合成叔丁基苯酚的影响,并获得合成叔丁基苯酚的最佳工艺条件,即反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5、重时空速2.2 h~(-1),该最佳反应条件下,PW_(12)@SBA-15/Apts催化剂催化合成叔丁基苯酚的催化活性最高,苯酚转化率为98.3%,2,4-二叔丁基苯酚选择性为57.3%.     

Intersecting Xenobiology and Neometabolism To Bring Novel Chemistries to Life

The diversity of life relies on a handful of chemical elements (carbon, oxygen, hydrogen, nitrogen, sulfur and phosphorus) as part of essential building blocks; some other atoms are needed to a lesser extent, but most of the remaining elements are excluded from biology. This circumstance limits the scope of biochemical reactions in extant metabolism – yet it offers a phenomenal playground for synthetic biology. Xenobiology aims to bring novel bricks to life that could be exploited for (xeno)metabolite synthesis. In particular, the assembly of novel pathways engineered to handle nonbiological elements (neometabolism) will broaden chemical space beyond the reach of natural evolution. In this review, xeno-elements that could be blended into nature's biosynthetic portfolio are discussed together with their physicochemical properties and tools and strategies to incorporate them into biochemistry. We argue that current bioproduction methods can be revolutionized by bridging xenobiology and neometabolism for the synthesis of new-to-nature molecules, such as organohalides.     

Calcium phosphates grown on bacterial cellulose template

Bacterial cellulose membranes were employed as templates for calcium phosphates deposition by successive immersion in solutions of Ca(NO₃)₂·4H₂O and (NH₄)₂HPO₄, under ultrasonication. During the wet chemical reaction, mineral phases were loaded on bacterial cellulose fibrils, leading to precursor hybrid composites. These were subjected to a lyophilisation procedure in order to preserve the 3D porous aspect and afterwards to a thermal treatment with the aim of removing the polymeric phase and generating well crystallized structures. Different types of morphologies were achieved by varying the heating rate, as well as the calcination temperature and period. The as-prepared samples and the final ones were investigated from compositional and structural point of view through X-ray diffraction and Fourier-transform infrared spectroscopy and morphologically concerning by scanning electron microscopy. The magnetic properties were also evaluated in order to demonstrate the suitability of the obtained materials for the development of magnetic scaffolds dedicated to hard tissue applications.     

Synthesis of nanoporous Baghdadite by a modified sol-gel method and its structural and controlled release properties

In this research, a bimodal nanoporous Baghdadite (NB) (Ca3ZrSi2O9) was prepared by a modified sol-gel method using P123 as a surfactant. The effects of P123's contents on the structural and textural properties as well as the drug delivery behavior of NB were assessed in vitro. The usage of P123 offered a new route for the synthesis of NB. The synthesized NB samples with different amounts of P123 were studied through X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM) equipped with energy-dispersive X-ray analysis spectroscopy (EDAX) and transmission electron microscopy (TEM). The results showed that a single-phase Baghdadite was obtained by this new method at the calcination temperature of 800?°C. It was found that an increase in P123's content up to 0.025?mol changed the morphology of NB samples from mountain-like to needle-like. The potential application of NB samples as drug delivery agents was assessed by estimating their release properties up to 240?h. This research revealed that the synthesized Baghdadite could be used as a potential nanoporous carrier with controlled release capability in bone tissue regeneration.     

建筑工程地基检测技术要点分析及优化对策

针对建筑工程的地基检测技术进行重点分析,并且相应的提出了检测技术的优化对策,以此来促进建筑工程得以顺利发展。     

抗凝冰乳化沥青涂层的性能研究

为了研究自制融雪剂对抗凝冰乳化沥青涂层性能的影响,将自制固态型融雪剂按5%、10%、15%的比例加入乳化沥青制备涂层乳液,采用水煮法、摆式摩擦仪、电导率试验分别对涂层材料的粘附性、抗滑性能和抗凝冰性能进行了测试。结果表明:自制型融雪剂对乳化沥青与集料的粘附性影响不大;随着融雪剂掺配比例的增大,抗凝冰乳化沥青涂层的摩擦系数有所降低,但均满足规范要求;相比于普通沥青涂层,抗凝冰乳化沥青涂层的抗凝冰性能得到改善,且随着融雪剂掺配比例的增大,凝冰性能逐渐提高。     

地外人工光合成材料研究进展

太空探索已成为人类共同目标,重返月球、载人火星等人类历史上的重大里程碑任务已逐步实施。如何实现地外极端环境下人类生存和发展已成为载人太空探索的基本能力和基础技术。由南京大学和钱学森空间技术实验室提出的地外人工光合成技术,模拟地球绿色植物的自然光合作用,利用密闭空间废弃资源或地外天体环境中丰富的资源,通过光电催化方法原位、加速、可控地将二氧化碳转化成为氧气和含碳燃料,大幅度降低载人航天器的物资供应需求,支撑可承受、可持续的载人深空探索。本文回顾了近年来国际航空航天领域利用二氧化碳转换生成氧气和碳氢燃料的现有方法,并深入探讨面向地外原位资源利用的人工光合成材料研究进展,期望深化对地外人工光合成材料与技术的认知,有力支撑载人航天发展。     

Effect of carbon nanotubes on structure and properties of the antifriction coatings produced by plasma cladding

Abstract

Due to their high antifriction characteristics, the Sn-Sb-Cu alloys (referred to as babbits) are widely used to coat sliding bearings. However, some limitations of the present techniques for applying such coating materials cause a decrease in their fatigue strength because of the reinforcing phase particles growth. As a technique for restricting the increasing of the reinforcing particle sizes, this paper proposes plasma surface cladding with multiwall carbon nanotubes (MWNTs) as modifiers. The dry sliding friction tests performed according to the “pin-on-disk” scheme using as a counterface a steel 100Cr6 (DIN 17230) disk have shown that adding to the coating 0.25%wt of CNTs significantly improves the friction stability (the coefficient of friction process stability decreases twice with reducing the friction coefficient and wear resistance by 5% on the average). An attempt to reveal the mechanism for the MWNT influence on the structure and performance of the babbit-based coatings was undertaken. Studies of the coatings metal structure by soft X-ray absorption spectroscopy and also by the metallographic and fractographic analysis involving electron-microscopy have shown that MWNTs remain stable during plasma cladding process and save into the coating.