Visible‐Light‐Promoted Synthesis of 1,4‐Dicarbonyl Compounds via Conjugate Addition of Aroyl Chlorides

A facile visible‐light photocatalytic conjugate addition to prepare 1,4‐dicarbonyl compounds has been developed by employing readily available aroyl chlorides as aryl radical sources. This operationally simple method shows a broad scope with regard to both aroyl chlorides and Michael acceptors. As a result, a variety of 1,4‐diketones were efficiently synthesized in moderate to good yields.     

Adsorption sensitivity of defected graphene towards NO molecule: a DFT study

Based on density functional theory, we studied the adsorption of a nitrogen monoxide (NO) molecule on the surface of perfect graphene (PG) and vacancy-defected graphene (VG), with the aim of searching the potential of graphene as an NO gas sensor. Different possible configurations have been considered for adsorption on vacancy-defected graphene split. The results indicated that the adsorption of the NO molecule on VG exhibited larger adsorption energy, higher charge transfer, smaller band length than that of perfect graphene. Meanwhile, the VG structure transformed a semiconductor into a conductor by the adsorption of the NO molecule. Furthermore, the partial electronic density of states (PDOS) results showed that hybridizations between the NO molecule and VG were mainly contributed by N-2p, O-2p, and C-2p orbitals. These results could provide useful information for the design of gas sensors based on graphene.     

Structure and Bonding in CE5− (E=Al–Tl) Clusters: Planar Tetracoordinate Carbon versus Pentacoordinate Carbon

The structure, bonding, and stability of clusters with the empirical formula CE₅^? (E=Al–Tl) have been analyzed by means of high‐level computations. The results indicate that, whereas aluminum and gallium clusters have C_2v structures with a planar tetracoordinate carbon (ptC), their heavier homologues prefer three‐dimensional C_4v forms with a pentacoordinate carbon center over the ptC one. The reason for such a preference is a delicate balance between the interaction energy of the fifth E atom with CE₄ and the distortion energy. Moreover, bonding analysis shows that the ptC systems can be better described as CE₄^?, with 17‐valence electrons interacting with E. The ptC core in these systems exhibits double aromatic (both σ and π) behavior, but the σ contribution is dominating.     

Neutron-gamma-ray transmission gauge

A transmission gauge using neutron- ray beam to measure two parameters simultaneously is reported. In the first place, it was used to measure the moisture m and the mass M of the choir-pottery material sample. The m and M are functions of the neutron transmissivity T_n and the -ray transmissivity T. The parameters of the function relationship can be got by the experiment calibration. Through the practical examination, the measured precision for the mass is 0.4g, for the moisture is 0.1%.     

A novel method for determination of peroxynitrite based on hemoglobin catalyzed reaction

A novel spectrofluorimetric method for the determination of peroxynitrite is proposed. The method is based on a mimetic enzyme catalyzed reaction with hemoglobin as the catalyst and l-tyrosine as the substrate. A new fluorescent substance is produced that might probably be the coupled dimmer of tyrosine, which, instead of nitryl-tyrosine, is likely to be a new marking substance of ONOO⁻ injury in vivo. Kinetics of the reaction is studied and the possible reaction mechanism is also recommended. The proposed method is simple and highly sensitive with a detection limit of 5.00 × 10⁻⁸ mol L⁻¹ of peroxynitrite. A liner calibration graph is obtained over the peroxynitrite concentration range 5.60 × 10⁻⁷ to 2.10 × 10⁻⁵ mol L⁻¹, with a correlation coefficient of 0.9983. Interferences from some amino acids and metal ions normally seen in biological samples, and also some anions structurally similar to ONOO⁻ are studied.     

Methane Decomposition into Carbon Fibers over Coprecipitated Nickel-Based Catalysts

Decomposition of methane in the presence of coprecipitated nickel-based catalysts to produce carbon fibers was investigated. The reaction was studied in the temperature range of 773 K to 1073 K. At 1023 K, the catalytic activities of three catalysts kept high at the initial period and then decreased with the reaction time. The lifetimes of Ni-Cu-Al and Ni-La-Al catalysts are longer than that of Ni-Al catalyst. With three catalysts, the yield of carbon fibers was very low at 773 K. The yield of carbon fibers for Ni-La-Al catalyst was more than those for Ni-Al and Ni-Cu-Al catalysts. For Ni-La-Al catalyst, the elevation of temperature from 873 K up to 1073 K led gradually to an increase in the yield of carbon fibers. XRD studies on the Ni-La-Al catalyst indicate that La2NiO4 was formed. The formation of La2NiO4 is responsible for the increase in the catalytic lifetime and the yield of carbon fibers synthesized on Ni-La-Al at 773 1073 K. Carbon fibers synthesized on Ni-Al catalyst are thin, long carbon nanotubes. There are bamboo-shaped carbon fibers synthesized on Ni-Cu-Al catalyst. Carbon fibers synthesized on Ni-La-Al catalyst have large hollow core, thin wall and good graphitization.     

异喹啉及其衍生物的表面增强喇曼光谱研究

采用表面增强喇曼光谱（ＳＥＲＳ）技术获得了异喹啉及其衍生物（３－羧基异喹啉、１－羧基异喹啉、甲基－３－异喹啉羧酸酯、１－羟基异喹啉、５－羟基异喹啉、１，５－二羟基异喹啉）的ＳＥＲＳ谱图，谱带分析表明由于异喹啉环上取代基不同、取代位置不同，均可导致其ＳＥＲＳ光谱的变化。其中１－羟基异喹啉、甲基－３－异喹啉羧酸酯、３－羧基异喹啉、异喹啉是垂直吸附于银胶表面。而１，５－二羟基异喹啉与５－羟基异喹啉则是通过环上π电子云平躺吸附于银胶表面。     

Influence of Gas Components on the Formation of Carbonyl Sulfide over Water-Gas Shift Catalyst B303Q

Water-gas shift reaction catalyst at lower temperature (200—400℃) may improve the conversion of carbon monoxide. But carbonyl sulfide was found to be present over the sulfided cobalt-molybdenum/alumina catalyst for water-gas shift reaction. The influences of temperature, space velocity, and gas components on the formation of carbonyl sulfide over sulfided cobalt-molybdenum/alumina catalyst B303Q at 200—400℃were studied in a tubular fixed-bed quartz-glass reactor under simulated water-gas shift conditions. The experimental results showed that the yield of carbonyl sulfide over B303Q catalyst reached a maximum at 220℃with the increase in temperature, sharply decreased with the increase in space velocity and the content of water vapor, increased with the increase in the content of carbon monoxide and carbon dioxide, and its yield increased and then reached a stable value with the increase in the content of hydrogen and hydrogen sulfide. The formation mechanism of carbonyl sulfide over B303Q catalyst at 200—400℃was discussed on the basis of how these factors influence the formation of COS. The yield of carbonyl sulfide over B303Q catalyst at 200-400℃was the combined result of two reactions, that is, COS was first produced by the reaction of carbon monoxide with hydrogen sulfide, and then the as-produced COS was converted to hydrogen sulfide and carbon dioxide by hydrolysis. The mechanism of COS formation is assumed as follows: sulfur atoms in the Co9S8-MOS2/Al2O3 crystal lattice were easily removed and formed carbonyl sulfide with CO, and then hydrogen sulfide in the water-gas shift gas reacted with the crystal lattice oxygen atoms in CoO-MoO3/Al2O3 to form Co9S8-MoS2/Al2O3. This mechanism for the formation of COS over water-gas shift catalyst B303Q is in accordance with the Mars-Van Krevelen's redox mechanism over metal sulfide.     

Preparation of A New Fiber by Sol-gel Technology in Solid-phase Microextraction （SPME）

The sol-gel technology is applied for the preparation of solid-phase microextraction (SPME) fiber. The fiber demonstrates high thermal stability, efficient extraction rate and the selectivity for non-polar or low-polar analytes. Efficient SPME-GC-FID analyses of benzenetoluene-ethylbenzene-xylenes (BTEXs) and low-polar halocarbon were achieved by the sol-gel coated DSDA-DDBT-TiO2 fiber. Some parameters of the SPME fiber for the determination of halocarbon in aqueous sample were investigated.