基于SSPCM的新型储能型太阳能蒸馏器实验研究

本文基于定型相变材料(SSPCM)建立了新型储能型太阳能蒸馏器的实验系统,并分别对普通SSPCM和高导热SSPCM的蒸馏特性进行了实验研究。研究发现:与传统太阳能蒸馏器相比,基于普通SSPCM的储能型蒸馏器的日产量提升了7.5%,采用高导热SSPCM的日产量提升了39%。此外,本文还对蒸馏器结构进行了优化研究,研制出了太阳能选择性吸收涂层和V型波纹板复合结构两种底衬,与普通底衬相比,两种优化的底衬分别使蒸馏器的日产量提高了16.8%和9.6%。     

稀释剂对H2/CH4预混火焰熄灭特性影响

掺氢天然气在稀释气体作用下的熄灭特性研究对实际燃烧设备的设计和优化具有重要的指导意义。本文利用对冲火焰法测量了掺氢天然气层流火焰在N₂和CO₂作用下的熄灭拉伸率,并采用数值模拟耦合详细化学反应机理对N₂,CO₂和He的稀释剂效应展开研究。结果表明,Li、GRI Mech 3.0和FFCM-1机理均能定性反映燃料熄灭拉伸率随当量比的变化规律,且FFCM-1机理综合预测精度最高。实验和模拟发现,不同稀释剂气体对掺氢天然气熄灭拉伸率降低幅度满足:He22。进一步研究发现,CO₂由于热容大,在反应体系中会降低火焰温度,同时增强了链终止反应强度,通过热效应和化学效应两方面对火焰熄灭特性起作用。He则能显著改变燃料混合物的平均摩尔质量,从而改变体系中重要反应物和自由基的扩散特性,从扩散效应方面影响火焰的熄灭特性。     

Polyacetylene‐Type Networks Prepared by Coordination Polymerization of Diethynylarenes: New Type of Microporous Organic Polymers

Microporous organic polymers (MOP) of a new type have been synthesised in high yields by a simple coordination polymerization of 1,3‐diethynylbenzene, 1,4‐diethynylbenzene and 4,4′‐diethynylbiphenyl catalysed by [Rh(cod)acac] and [Rh(nbd)acac] complexes. The new MOPs are non‐swellable polyacetylene‐type conjugated networks consisting of ethynylaryl‐substituted polyene main chains that are crosslinked by arylene linkers. Prepared MOP samples have a mole fraction of branching units (by ¹³C CP/MAS NMR) from 0.30 to 0.47 and exhibit the BET (Brunaer‐Emmett‐Teller) surface up to 809 m² g⁻¹ and hydrogen uptake up to 0.69 wt% (77 K, H₂ pressure 750 torr).     

Single Chain Folding of Synthetic Polymers by Covalent and Non‐Covalent Interactions: Current Status and Future Perspectives

The present feature article highlights the preparation of polymeric nanoparticles and initial attempts towards mimicking the structure of natural biomacromolecules by single chain folding of well‐defined linear polymers through covalent and non‐covalent interactions. Initially, the discussion focuses on the synthesis and characterization of single chain self‐folded structures by non‐covalent interactions. The second part of the article summarizes the folding of single chain polymers by means of covalent interactions into nanoparticle systems. The current state of the art in the field of single chain folding indicates that covalent‐bond‐driven nanoparticle preparation is well advanced, while the first encouraging steps towards building reversible single chain folding systems by the use of mutually orthogonal hydrogen‐bonding motifs have been made.     

纳米TiO2薄膜的制备与光催化性能研究

以四氯化钛为前驱体,采用水解沉淀法,在不同的水解温度下,在硅藻土基多孔陶瓷上负载纳米TiO2薄膜,结合XRD和TEM对负载的纳米TiO2粒径进行了表征。对比分析了测试方法及水解温度对纳米TiO2粒径的影响。以罗丹明B为目标降解物,考察了水解温度对光催化剂活性的影响。结果表明:样品经550℃煅烧后,TiO2薄膜为锐钛矿型;水解温度为50℃时TiO2粒径小于水解温度为75℃时所负载纳米TiO2粒径;两种方法所测TiO2粒径有一定差异:dXRD>dTEM;水解温度为50℃所负载纳米TiO2薄膜,紫外光照300 min,对罗丹明B的去除率为89.9%,而75℃时,样品在紫外光照330 min,对罗丹明B的去除率为78.6%。     

奇异摄动法简化化学反应机理

本文简单介绍了奇异摄动方法简化化学反应机理的原理,通过对反应过程中不同反应模态的特征时间来区分反应过程中的快慢模态,并由此确定简化机理的组分数,对氢气/空气、甲烷/空气的燃烧机理分别用CSP方法做简化,对GRI-2.11的简化机理论与详细机理对点火延迟时间和火焰传播速度进行了较宽压力和当量比下的验证,结果证明了该方法的有效性和准确性。同时也讨论了不同反应快模态数的选择对结果会产生的影响,为得到能模拟点火过程的简化机理提供一种参考方法。     

Combining Modular Ligation and Supramolecular Self‐Assembly for the Construction of Star‐Shaped Macromolecules

A well‐defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties with an alkyne terminal group is prepared (P(S‐co‐CMS), = 5500 Da, PDI = 1.13). The chloromethyl groups are converted into Hamilton wedge (HW) entities (P(S‐co‐HWS), = 6200 Da, PDI = 1.13). The P(S‐co‐HWS) polymer is subsequently ligated with tetrakis(4‐azidophenyl)methane to give HW‐functional star‐shaped macromolecules (P(S‐co‐HWS))₄, = 25 100 Da, PDI = 1.08). Supramolecular star‐shaped copolymers are then prepared via self‐assembly between the HW‐functionalized four‐arm star‐shaped macromolecules ( P(S‐co‐HW )) ₄ and cyanuric acid (CA) end‐functionalized PS (PS–CA, = 3700 Da, PDI = 1.04), CA end‐functionalized poly(methyl methacrylate) (PMMA–CA, = 8500 Da, PDI = 1.13) and CA end‐functionalized polyethylene glycol (PEG–CA, = 1700 Da, PDI = 1.05). The self‐assembly is monitored by ¹H NMR spectroscopy and light scattering analyses.     

Effects of ion exchange and calcinations on the structure and photocatalytic activity of hydrothermally prepared titanate nanotubes

Titanate nanotubes (TiNTs) were prepared by alkaline hydrothermal processing. The TiNTs are thermodynamically unstable and easily transformed to the titania phase by heat or acid treatment. These phase transformations are affected by the preparation conditions. In this study, we investigated the effects of using the washing process to modify the sodium content of the TiNTs. After an alkaline hydrothermal process was used to prepare the TiNTs, the resulting suspensions were washed with weak acid solution and distilled water until the pH value of the wash solution reached approximately 1 or 7, and the products were identified as H‐TiNTs or Na‐TiNTs, respectively. The characteristics and photocatalytic activities of the H‐TiNTs and Na‐TiNTs were compared for various calcination temperatures. The H‐TiNTs were transformed completely to anatase‐type TiO₂ by dehydration during calcination, while the crystallinity of the Na‐TiNTs increased with calcination temperature. However, the photocatalytic H₂ production rates on calcined H‐TiNTs were much higher than on Na‐TiNTs, which could be attributed to the crystalline anatase phase.     

全原子分子动力学模拟研究丙氨酸二肽水溶液的结构和氢键作用

采用全原子分子动力学模拟研究了丙氨酸二肽分子在水溶液中的结构和氢键作用。径向分布函数和氢键统计用于分子动力学模拟的分析。从径向分布函数（RDF）发现不同类型的强氢键显示出不同的形成能力,而体系中的C−H•••O弱相互作用较为明显,也不能忽略。氢键统计分析的结果也证实了这一点。分子内距离、回转半径和骨架二面角用于表征丙氨酸二肽分子在水溶液中的构象变化。丙氨酸二肽分子在水溶液中的柔顺性较好,构象在折叠和伸展之间相互转换。     

基于负氢离子源的全三维PIC/MCC模拟算法研究

在分析负氢离子源中等离子体物理机理基础下, 研究并优化粒子模拟算法, 设计高效的粒子存储方法. 研究并运用粒子碰撞蒙特卡罗方法, 考虑等离子体势以及带电粒子间库仑碰撞, 研制了全三维粒子模拟/蒙特卡罗算法(PIC/MCC). 采用磁荷模型, 运用时域有限差分方法计算多峰磁场, 并结合国外负氢离子源JT-60U, 考虑负氢离子源中主要反应, 对全三维PIC/MCC模拟算法模拟验证.