使用地热能的吸收式制冷系统

吸收式制冷系统可以利用低品位的热源来制冷，相对于常见的蒸汽压缩式制冷系统而言在这方面具有优势。我国是一个地热资源很丰富的国家，为了充分利用这一资源，我们有必要对以地热为热源的吸收式制冷系统进行研究。本文着重分析了使用地热资源的溴化锂吸收式制冷系统。     

两种不同石墨电极上溴离子电氧化的研究

通过测定溴离子在两种不同石墨电极上的循环伏安曲线及电流效率，探索了溴离子在石墨电极上氧化的电解条件，比较了两种石墨电极对溴离子电氧化的影响。研究发现，由于电极材料的不同和析氧反应的存在，两种电极材料对溴离子氧化的催化作用有一定差别。溴离子在石墨电极上氧化的电流效率一般在80％以上，最高可达88．5％。     

Effect of calcination temperature on the characteristics of SO<Emphasis Type="Italic">sk</Emphasis>4/2-/TiO<Subscript>2</Subscript> catalysts for the reduction of NO by NH<Subscript>3</Subscript>

The catalytic activity of sulfated titania (ST) calcined at a variety of temperatures has been investigated for selective catalytic reduction (SCR) of NO by NH₃. The NO removal activity of ST catalyst mainly depends on its sulfur content, indicating critical role of sulfur species on the surface of TiO₂. The role of sulfur is mainly the formation of acid sites on the catalyst surface. The presence of both BrØnsted and Lewis acid sites on the surface of sulfated titania has been identified by IR study with the adsorption of NH₃ and pyridine on ST. The reduction of the intensity of IR bands representing BrØsted acid sites is more pronounced than that revealing Lewis acid sites as the calcination temperature increases. It has been further clarified by IR study of ST500 catalyst evacuated at a variety of temperatures. The NO removal activity also decreases with the increase of the catalyst calcination temperature. It simply reveals that BrØnsted acid sites induced by sulfate on the catalyst surface are primarily responsible for the enhancement of catalytic activity of ST catalyst containing sulfur for NO reduction by NH₃.     

Chlorophyll adsorption on acid-activated clay

An acid-activated clay (Çanakkale montmorillonite from Turkey) was used to adsorb chlorophyll from hexane solutions. The phenomenon seems to be mainly driven by the interaction of chlorophyll with acid sites. The adsorption of chlorophyll on Brönsted acid sites was indicated by a characteristic infrared band for the -OH group at 3671 cm^?1. The variations in the structure of clay mineral and chlorophyll during adsorption have been examined by differential thermal analysis, thermogravimetry and infrared spectroscopy of the activated clay before and after adsorption of chlorophyll. Oxidation of adsorbed chlorophyll was completed at quite a high temperature.     

Vapor Phase Growth of Centimeter-Sized Band Gap Engineered Cesium Lead Halide Perovskite Single-Crystal Thin Films with Color-tunable Stimulated Emission

Single crystal metal halide perovskites thin films are considered to be a promising optical, optoelectronic materials with extraordinary performance due to their low defect densities. However, it is still difficult to achieve large-scale perovskite single-crystal thin films (SCTFs) with tunable bandgap by vapor-phase deposition method. Herein, the synthesis of CsPbCl_3(1–x)Br_3x SCTFs with centimeter size (1 cm × 1 cm) via vapor-phase deposition is reported. The Br composition of CsPbCl_3(1–x)Br_3x SCTFs can be gradually tuned from x = 0 to x = 1, leading the corresponding bandgap to change from 2.29 to 2.91 eV. Additionally, an low-threshold (≈23.9 µJ cm⁻²) amplified spontaneous emission is achieved based on CsPbCl_3(1–x)Br_3x SCTFs at room temperature, and the wavelength is tuned from 432 to 547 nm by varying the Cl/Br ratio. Importantly, the high-quality CsPbCl_3(1–x)Br_3x SCTFs are ideal optical gain medium with high gain up to 1369.8 ± 101.2 cm⁻¹. This study not only provides a versatile method to fabricate high quality CsPbCl_3(1–x)Br_3x SCTFs with different Cl/Br ratio, but also paves the way for further research of color-tunable perovskite lasing.     

Electrochemically induced hydrogenolysis of 1,1-dibromoalkenes to vinyl bromides

Vinyl bromides 2a-f, useful intermediates in organic synthesis, have been obtained under mild conditions and in good yields via electrochemical reduction of 1,1-dibromoalkenes 1a-f (readily available substrates). The reduction has been carried out in MeCN-tetraethylammonium perchlorate (TEAP) solutions, in the presence of a proton donor, at a Au, Hg, C or Ag cathode. The use of specific reducing agents, catalysts and bases, employed in the classical procedures, has been avoided. The isomeric E/Z ratio in vinyl bromides 2a-f is affected by the cathode material.     

Catalytic Activities of Alcohol Transformations Over 8-Ring Zeolites

Aluminosilicate H/CHA and H/MTF zeolites show remarkably different catalytic activities in the methanol and ethanol transformations although they have similar pore size of 8-membered ring structures. Moreover, the produced ethylene is further converted on H/CHA, but H/MTF is not active for the ethylene transformation. The correlations between the distinct catalytic differences and their intrinsic structural properties, including topology and acidity, are discussed.     

Characterization of H-FER and H-TON using temperature-programmed desorption of alkylamines

Simultaneous temperature-programmed desorption (TPD) and thermogravimetric analysis (TGA) measurements were performed with n-propylamine and isopropylamine in H-FER and H-TON in order to test whether the Brønsted-acid sites associated with the 10-ring, straight channels in H-FER could be distinguished from the acid sites in the side cavities. In H-TON, the saturation uptakes were identical for both amines, as were the acid-site densities determined from the amounts of amine which reacted to olefin and ammonia products above 600 K. By contrast, the saturation uptake for isopropylamine in H-FER was much lower than the uptake of n-propylamine and the site density determined from the amounts which react were also significantly lower. It is argued that the n-propylamine results for H-FER provide a measure of the total Brønsted-acid-site density, while the isopropylamine results provide a measure of the site density in the 10-ring channels.     

CH3ONO 与 Br 自由基反应的机理研究

运用量子化学B3LYP方法,在6－311＋＋g（ d,p）基组水平上研究Br自由基和CH3 ONO的反应机理,优化得到了反应途径上反应物、过渡态和产物的几何构型;在B3LYP／6－311＋＋g（ d,p）优化的构型基础上,以CPCM模型得到了其在水溶液中各点的能量。研究结果表明：Br自由基与CH3 ONO有3种反应机制。第1种是Br自由基加成到CH3 ONO分子C原子上消除NO2的机制,第2种是Br自由基加成到CH3 ONO分子甲氧基O原子上消除NO的加成－消除机制,第3种是Br自由基对H直接夺取的机制。     

天然抗氧化剂的筛选

对７００余种中药和香辛料的抗氧化活性进行了大规模的筛选，发现有６４种植物有明显的抗氧化活性，２４种植物的抗氧化活性很强。其中有几种植物的抗氧化活性的筛选和研究，如荔枝草，降真香，紫草，血竭是以前未见报道过的。