Preparation of porous α-Fe_2O_3-supported Pt and its sensing performance to volatile organic compounds

Porous α-Fe2O3 was synthesized by a simple hydrothermal treatment of FeC13 aqueous solution followed by a calcination process. In the synthesis of porous α-Fe2O3, no templates or pore-directing agents were used. The as-prepared porous α-Fe2O3 was further employed as a support for loading Pt nanoparticles. The gas sensing performance of the obtained porous α-Fe2O3-supported Pt to VOCs was investigated. The sensor presented a high response and fast response-recovery characteristic to several VOCs including acetone, ether, methanol, ethanol, butanol and hexanol. Meanwhile, it exhibited a much higher response than the pure α-Fe2O3 at the operating temperature of 260 ℃. The enhanced sensing properties may be related to the unique porous structure of the α-Fe2O3 support and the promoting effect of active Pt nanoparticles for the sensing reactions.

Preparation and Characterization of TiO₂Photocatalytic Thin Film and Its Compounds by Micro-Arc Oxidation Technique

Mesoporous TiO2 ceramic films have been prepared upon the Ti alloy substrate by the micro-arc oxidation (MAO) technology. To enhance the photo-catalytic property of the films, Eu2O3 particles were added into the electrolyte solution of Na2CO3/Na2SiO3. Scanning electron microscope (SEM), energy dispersive (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) are employed to characterize the modified films. Diffuse reflectance spectra (DRS) test, photo-generated current test and photo decomposition test are applied to evaluate the photo-catalytic property of the modified films. The results show that Eu2O3 transformed into one-dimensional (1-D) nano-wires embedded within the composite film, and the film has high photo-catalytic property.

[Hmim]_3PW_(12)O_(40):A high-efficient and green catalyst for the acetalization of carbonyl compounds

[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.

MICHAEL ADDITION OF NITROALKANE TO α,β-UNSATURATED CARBONYL COMPOUNDS ON KF / Al_2O_3/ PEG4000

Michael addition of nitroalkanes to α,β-unsaturated carbonyl compounds occurs in the presence of KF/AI_2O_3/PEG4000 without solvent.Yields are fair to good and work-ups are easy.

Analysis of Volatile Compounds and Identification of Characteristic Aroma Components of <i>Toona sinensis</i>(A. Juss.) Roem. Using GC-MS and GC-O

In this study, volatile compounds present in Toona sinensis (A. Juss.) Roem (TS) were investigated and their characteristic aromatic components were identified using Headspace Solid-phase Microextraction (HS-SPME) followed by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). The optimum conditions for extracting the volatiles from TS were achieved with the experimental parameters including the use of a 65 μm polydimethylsiloxane/divinyl benzene (PDMS/DVB) fibre, an extraction temperature of 40℃ and an extraction time of 30 min. Under these conditions, 56 volatile compounds were separated and 53 were identified by GC-MS. Among them, 21 sulfide compounds (42.146%) and 27 terpenes(55.984%) were found to be the major components. The sample was analyzed by GC-O and 26 elutes were sniffed and their sensory descriptions evaluated by an odor panelists. Analysis of the data indicated, two compounds cis and trans isomers of 2-Mercapto-3,4-dimethyl-2,3-dihydrothiophene were major contributors to the characteristic aroma of TS.

Valence Distribution in AT_xV_(6-X)O_(11) Compounds

The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution

Induction of Volatile Organic Compounds in Leaves of Lycopersicon Esculentum by Nd^(3+)

The effects of Nd^3＋ on the quality and quantity of volatile organic compounds （VOCs） in the leaves of Lycopersicon esculentum were studied. The results demonstrate that Nd^3＋ can increase the total amount of VOC by 75% after treatment for 120 h, as compared with the control. Phyto-oxylipins, terpenoids and aromatic compounds were increased by 73%, 38% and 21%, respectively. （E）-2-hexenal, the most abundant constituent is increased by 74%, β- phellandrene and α-caryophyllene in terpenoids,

Activation of Carcinogenic Non-aminoazo Compounds in Horseradish Peroxidase/H_2O_2 System

Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identified as the benezenediazonium ion, the ultimate carcinogens, which could bind to DNA. The reaction conditions were investigated preliminarily. Some inhibitors and inducers of the reaction were discovered.

Influence of Reactive Volatile Organic Compounds on Ozone Production in Houston-Galveston-Brazoria Area

Secondary pollutant ozone (O3) formation in a particular area is often influenced by various factors. Source of emissions is one of the factors. In south east Texas, Houston-Galveston-Brazoria (HGB) is a marginal non-attainment area for ozone (O3). A summer episode of May 28 to July 2, 2006 is simulated using Comprehensive Air Quality Model with extensions (CAMx). During this period O3 concentration in HGB often exceeds the National Ambient Air Quality Standards (NAAQS) 0.075 ppm of average 8 hour O3 concentration. HGB area has numerous point sources. Various studies found that some specific volatile organic compounds are very reactive in atmosphere. The objective of this study is to analyze the influence of volatile organic compounds present in point source emissions on the air quality of HGB area. For this purpose ozone sensitivity for HGB area is analyzed by the ratio of hydrogen peroxides (H2O2) to nitric acid (HNO3). HGB area is found NOx limited but reactive VOCs are found to be influential too. From (1-4 June, 2006) maximum O3 concentration was found on weekend, June 3. VOCs such as Acetaldehyde (ALD2), Formaldehyde (FORM) and Alkane (ETHA) showed good correlation with O3 concentrations on that day. In addition, Peroxyacetyl nitrate (PAN) formation was found correlated to higher ozone production. Criteria pollutant Sulfur dioxide (SO2) was found to influence the ALD2 and ETHA concentrations, and thus indirectly influenced O3 production.

Polarizabilities and Orientational Order Parameter in N-(p-n-Ethoxybenzylidene)- p-n-Alkoxy Anilines, 2O.Om LC Compounds

n.m, n.Om, nO.m and nO.Om compounds play an important role in the fundamental and applied aspects. As a part of our systematic studies of the above homologous series regarding the synthesis, characterization and phase transition studies, here the authors report the polarizabilities and orientational order parameter, S in N-(p-n-ethoxybenzylidene)-p-n-alkoxy anilines, 2O.Om with m = 3 to 10 liquid crystalline compounds except with m = 5 which has been already published. The rest of the compounds exhibit the nematic LC phase except with m = 10 which shows the smectic-C phase along the nematic phase which is originally not detected by Godzwon et al. But the author’s observations with TM and differential scanning calorimeter have shown the existence on SmC phase in addition to nematic phase. Further, SmC is clarified using the histogram technique whose details are given below and are published elsewhere. The orientstonal order parameter, S is estimated using different methods and compared with the value obtained from birefringence, δn = (ne – no) where no field model is used. It is observed in these compounds case as in other LC compounds Vuks isotropic model is favored compared to that of anisotropic model proposed by Neugebauer.

Stereoselective Addition of N-Alkylhydroxylamines to α,β-Unsaturated Nitro Compounds

N-Alkylhydroxylamines have been shown to undergo a stereospecific cis addition to 1-phenyl-2 -nitropropene compounds, whereas the corresponding O-alkylhydroxylamines give no diastereoselectivity. The concerted addition mechanism was provided to explain the difference.

Oxygen Relief/Absorption and Superconductivity of Bi-Pb-Sr-Ca-Cu-O Compounds

The oxygen relief/absorption,superconduc— tivity and structure of(Bi_(1-x)Pb_x)_2Sr_2Ca_2— Cu_3O_y compounds have been studied by TGA, electrical resistance measurement and X-ray diffraction.The amount of oxygen which can be re- leased and superconductivity of the compounds are correlative to Pb content.The release of oxygen in- creases when x less than 0.2 and decreases when x exceeds 0.2 with increasing x.The appropriate con- tent of Pb for superconductivity is in the range of 0.1<x<0.3,which corresponds to the relative large amount of oxygen that can be released.It is found according to electric resistance measurement that quenching is favourable to form the‘85K’phase and slow cooling the‘110K’phase.The experimen- tal results suggest that a relation exists between the superconductivity and the oxygen content in Bi sys- tem containing Pb.As the T_c of‘85K’phase de- creases and that of‘110K’phase increases with in- creasing oxygen content,it is possible that the effect of oxygen content in‘85K’phase and‘110K’ phase on the superconductivity is different.

基于Mono Tra p-GC-O-MS的西瓜汁热处理前后气味化合物分析

Mono Trap具有萃取量大、操作简便等特点,在西瓜汁气味化合物萃取上具有一定优势。采用Mono Trap、热脱附结合气相色谱-嗅闻-质谱萃取分析热处理前后西瓜汁气味化合物变化。使用RGC18、RSC18、RGPS这3种吸附材料从鲜榨和热处理西瓜汁样品中分别鉴定出50种和71种气味化合物。通过实验对比这3种吸附材料的萃取效果,结果显示,RGC18对西瓜汁气味化合物的萃取效果最好,利用RGC18从鲜榨和热处理西瓜汁中分别萃取到41种和53种气味化合物。西瓜汁在热处理后,风味物质发生了很大变化,呈现苦杏仁味、皂化味和酸刺味的2-甲基丁醛、糠醛、辛醛、癸醛、(E)-2-庚烯醛、乙酸和甲酸等化合物的香气活力值增大;呈现清香、柠檬气味的己醛、β-环柠檬醛和(E,E)-2,4-壬二烯醛不能被嗅闻到。这些气味化合物的变化是导致西瓜汁热处理后出现异味的重要原因。

6063-O铝合金Y型形管接头电磁成形

基于逆向识别结合平板电磁翻边实验建立6063-O铝合金的Johnson-Cook本构和失效判据,对比分析Y型管分离工序电磁翻边与电磁冲孔翻边复合成形两种方式下的电磁力分布、成形过程及变形特征,表明复合成形能成形出更高的支管并提高成形效率,更为有效地改善壁厚周向分布。在此基础上,进行电磁冲孔翻边复合成形实验,获得成形质量良好的Y型接头,探讨放电电压及管坯厚度对支管成形高度、端部壁厚以及贴模间隙的影响,分析成形支管轴向壁厚分布特征与典型缺陷。

复配条件对矢车菊素-3-O-葡萄糖苷与β-胡萝卜素复合模拟体系物化稳定性的影响

为探讨富含花色苷及类胡萝卜素的复合果蔬汁中花色苷及类胡萝卜素的降解机制,选择自然界中分布最广、含量最多的花色苷及类胡萝卜素——矢车菊素-3-O-葡萄糖苷(C3G)及β-胡萝卜素为对象,构建模拟体系,研究金属离子、pH值、糖种类及含量对C3G和β-胡萝卜素稳定性的影响。结果表明,C3G和β-胡萝卜素热降解均符合一级反应动力学,且两者的降解反应均为吸热非自发反应。C3G和β-胡萝卜素经复合后,C3G的稳定性无显著变化,而β-胡萝卜素稳定性降低。此外,不同糖种类及浓度对复合模拟体系中的C3G和β-胡萝卜素热降解的影响不同。糖类对C3G的促降解作用依次为果糖>蔗糖>葡萄糖,且随糖浓度的增大,花色苷稳定性逐渐增加。而3种糖类对β-胡萝卜素的作用不显著,且随糖浓度的增大,β-胡萝卜素稳定性逐渐下降。研究结果为富含花色苷及类胡萝卜素的复合果蔬汁的研发提供了理论依据。

SYNTHESIS AND X-RAY POWDER STUDY OF A NEW COMPOUND:Ba_6Ti_7Nb_9O_(42)

A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.

Synthesis and Thermoelectric Properties of Ca_(2.6)Nd_ ( 0.4)Co_4O_9 Compound

The layered cobaltite Ca 2.6Nd 0.4Co 4O 9 was synthesized by the solid-state reaction. Their crystal structure was determined by the X-ray powder diffraction and CELL program. The prepared Ca 2.6Nd 0.4Co 4O 9 compound has the monoclinic symmetry. The electrical conductivity and Seebeck coefficient were measured from room temperature to 700 ℃ in air. Both the properties increase while rising temperature. The thermoelectric power of Ca 2.6Nd 0.4Co 4O 9 is about 242 4 μV·K -1. The results imply a promising way to enhance the thermoelectric properties of the layered cobaltite oxides by optimizing their composition and microstructure.

SYNTHESIS AND STRUCTURE OF TETRANUCLEAR MOLYBDENUM CLUSTER COMPOUND[Mo_4S_4(μ-O_2CC_6H_5)_2(dtp)_4]

The cluster compound[Mo_4S_4(μ-O_2CC_5H_5)_2(dtp)_4](dtp=S_2P(OEt)_2)was obtained by the ligand substitution reaction of tetranuclear molybdenum cluster [Mo_4S_4(μ-dtp)_2(dtp)_4]in the mixed solvent of acetone,ethanol and water in the presence of C_6H_5CO_2Na.It is monoclinic and crystallizes in space group C2/c, Mr=1495.09,a=12.175(5),b=22.01(1),c=20.875(9),β=99.04(4)°;V=5575(5);Z=4; Dc=1.78g/cm^3.Final R factor is 0.066.The result reveals that the[Mo_4S_4]cluster core and t-(dtp)^(-1)ligands are retained and only μ-bridged(dtp)^(-1)ligands are substituted by(C_6H_5CO_2)^(-1)in the substitution reaction,thus producing the new title cluster compound,the structure of which contains two species of bidentate ligand.

Coexistence of Polaronic States and Superconductivity in Iron-Pnictide Compound Ba_2Ti_2Fe_2As_4O

The electronic structure of iron-pnictide compound superconductor Ba_2Ti_2Fe_2As_4O, which has metallic intermediate Ti_2O layers, is studied using angle-resolved photoemission spectroscopy. The Ti-related bands show a‘peak-dip-hump＇ line shape with two branches of dispersion associated with the polaronic states at temperatures below around 120 K. This change in the spectra occurs along with the resistivity anomaly that was not clearly understood in a previous study. Moreover, an energy gap induced by the superconducting proximity effect opens in the polaronic bands at temperatures below T_c（~21 K）. Our study provides the spectroscopic evidence that superconductivity coexists with polarons in the same bands near the Fermi level, which provides a suitable platform to study interactions between charge, lattice and spin freedoms in a correlated system.

IN-SITU HVEM STUDY ON PHASE TRANSITION OF YBa_2Cu_3O_(7-x) SUPERCONDUCTING COMPOUND IN PROCESS OF HEATING

In-situ HVEM observation on phase transition of the YBa_2Cu_3O_(7-x) superconducting compound in pro- cess of heating was carried out,and high temperature X-ray diffraction analysis in air and X-ray diffraction phase analysis for the sample treated in vacuum condition were made.The results showed that the temperature of phase transition is related to oxygen content in the sample and in general,is 100℃ to 120℃ lower in vacu- um condition than in air.At 320℃ to 350℃ twin bands begin to disappear,and some Cu_2O are formed on the surface of the sample and transit from orthorhombic YBa_2Cu_3O_(7-x) to arthorhombic Y_2BaCuO_5 compound. This transition was completed at about 500℃.Above 900℃,this compound consists of the Y_2BaCuO_5, BaCuO_2,Y_2O_3 and some other minor compounds.No phase transition was observed during cooling the sample.