乙醇羰化反应负载型催化剂的研究

本文由七种负载型催化剂中选出两种比较好的乙醇羰化催化剂,研究了影响反应转化率和选择性的因素,考察了活性组份的价态和载体的酸性。此外,还对催化剂进行了能量色散X射线分析。从其结果看,谱图上只有活性中心铑的谱峰而没有氯的谱峰,说明铑是以离子形式进入载体,而不是以化合物形式被吸附于载体上。     

Generation and reactions of substituted phenide anions in an electrospray triple quadrupole mass spectrometer

Substituted benzoic acid anions undergo decarboxylation in the medium-pressure region of an electrospray ion source yielding in most cases the correspondingly substituted phenide anions in high yield. The location of the anionic center is specified by the position of the carboxylic group. The only exceptions are compounds with substituents containing acidic hydrogen atoms, like OH and NH(2) groups. For such compounds, either an intra- or an intermolecular (mediated by the molecules of methanol or water) proton transfer from the more acidic position to the benzene ring is observed. The generated anions can be selected using the first quadrupole for studying their ion-molecule chemistry in the second quadrupole of a triple quadrupole mass spectrometer. Their reactions with CO(2), O(2), CH(3)COCH(3) and CCl(4) may serve as typical examples. The general applicability of this method for the generation of phenide anions has been confirmed on three different mass spectrometers. Experiments performed using carboxylic acids other then benzoic acid and its derivatives show that this method is not limited to phenide anions and can be used for the generation of a much wider range of carbanions in the gas phase.     

Sunlight-activated AlFeO3/TiO2 photocatalyst

A nanocomposite photocatalyst composed of AlFeO₃ and TiO₂ is prepared, and characterized through X-ray diffraction. Application of the nanocomposite for the photodegradations of eosin dye and methyl orange gives an improved photoactivity compared with TiO₂-only nanomaterials. The optimal concentration of AlFeO₃ in the composite is about 1.0 wt% under UV excitation, and 9.0 wt% under sunlight excitation for the improved photoactivity. Furthermore, this nanocomposite is more active for eosin photodegradation if natural sunlight rather than UV is used. This may be due to the reason that adding AlFeO₃ nanoparticles into TiO₂ matrix can promote the separation of photogener-ated charge carriers, and extend the photoresponse of TiO₂ toward visible region, which results in an increase in the solar energy utilization efficiency.     

Room temperature deposition of nanocrystalline cadmium peroxide thin film by electrochemical route

Nanocrystalline cadmium peroxide thin film has been electrodeposited on indium doped tin oxide glass substrate from aqueous solution at room temperature. The grain size of the nanocrystals of the film is estimated from XRD and is about 14 nm. The deposits are decomposed at 228 °C by formation of CdO, releasing plentiful heat at same time. The band-gap of the nanocrystalline CdO film made from decomposition of electrodeposited CdO₂ is around 2.4 eV.     

环状芴基张力半导体拉曼光谱理论与实验研究

环状芴基张力半导体由于其特殊的分子结构，发射状排布的p轨道和纳米级空腔等诸多特点，引起了科学家广泛的关注.相对于直链型芴基半导体，环状芴基张力半导体展现出独特的光电性质.然而，迄今为止其振动性质没有被报道.对四元环芴的晶体与直链四聚芴粉末样品进行拉曼光谱表征和归一化处理，并结合理论计算.结果表明，与直链寡聚芴相比，环芴类似于碳纳米管的G峰发生了偏移，并且低频区域拉曼频移峰的峰强增加.其原因是由于张力的引入，改变了芴基主链的骨架和电子结构，加强芴骨架上π电子离域，同时使环芴中每个芴单元都参与到振动中.该研究结果为芴基张力半导体材料拉曼光谱的研究提供了一定的工作基础.     

Studies on the synthesis of biphenylneolignans. Part 1: Enantioselective synthesis of (S,S)- and (R,R)-2,2′-dimethoxy-4-(3-hydroxy-1-propenyl)-4′-(1,2,3-trihydroxypropyl)diphenyl ether

Two erythro-isomers of 2,2′-dimethoxy-4-(3-hydroxy-1-propenyl)-4′-(1,2,3-trihydroxypropyl)diphenyl ether, (7′S, 8′S)-9 and (7′R, 8′R)-9, were synthesized in seven steps, in which an improved method for the synthesis of the key intermediate 3 was developed. The absolute configuration of the target molecules was also confirmed.     

Sarcophytolides G–L,New Biscembranoids from the Soft Coral Sarcophyton elegans

Six new biscembranoids, namely, sarcophytolides G–L ( 1 – 6 , resp.), together with six known analogs, were isolated from a marine soft coral Sarcophyton elegans. The structures of the new compounds were established on the basis of 1D‐ and 2D‐NMR (COSY, HSQC, HMBC, and NOESY) spectroscopic analysis together with the aid of MS, CD, and IR data. The unusual isobiscembranoid sarcophytolide G ( 1 ) was found for the first time in the genus Sarcophyton.     

Application of Dried Blood Spots and Serum Samples for the Determination of Vitamin D Metabolites in the Group of Healthy Women and with Hashimoto’s Thyroiditis

Chromatographia - The relationship between Hashimoto's thyroiditis and vitamin D concentration was already presented in many studies. The aim of this study was to analyze the differences in the...     

Hierarchical nanostructured composite cathode with carbon nanotubes as conductive scaffold for lithium-sulfur batteries

Carbon nanotubes (CNTs) are excellent scaffolds for advanced electrode materials, resulting from their intrinsic sp2 carbon hybridization, interconnected electron pathway, large aspect ratio, hierarchical porous structures, and low cost at a large-scale production. How to make full utilization of the mass produced CNTs as building blocks for nanocomposite electrodes is not well understood yet. Herein, a composite cathode containing commercial agglomerated multi-walled CNTs and S for Li-S battery was fabricated by a facile melt-diffusion strategy. The hierarchical CNT@S coaxial nanocables exhibited a discharging capacity of 1020 and 740 mAh g-1 at 0.5 and 2.0 C, respectively. A rapid capacity decay of 0.7% per cycle at the initial 10 cycles and a slow decay rate of 0.14% per cycle for the later 140 cycles were detected. Such hierarchical agglomerated CNT@S cathodes show advantages in easy fabrication, environmentally benign, low cost, excellent scalability, and good Li ion storage performance, which are extraordinary composites for high performance Li-S battery.