Direct reduction of SO2 to elemental sulfur by the coupling of cold plasma and catalyst (I)

The direct reduction of SO2 to elemental sulfur in flue gas by the coupling of cold plasma and catalyst, being a new approach for SO2 reduction, was studied. In this process, CO2 can be disassembled to form CO, which acts as the reductant under the cold plasma. With the coupling of the cold plasma and the catalyst, sulfur dioxide was selectively reduced by CO to elemental sulfur with a byproduct of metal sulfate, e.g., FeSO4. In the present work, Fe2O3/gamma-Al2O3 was employed as the catalyst. The extent of desulfurization was more than 80%, and the selectivity of elemental sulfur is about 55%. The effects of water vapor, temperature, and the components of simulated flue gas were investigated. At the same time, the coupling of thermogravimetry and infrared method and a chemical analysis method were employed to evaluate the used catalyst. In this paper, we will focus on the discussion of the catalyst. The discussions of the detail of plasma will be introduced in another paper.

Boundary Characterization Experiment Series Overview

Ocean acoustic propagation and reverberation in continental shelf regions is often controlled by the seabed and sea surface boundaries. A series of three multi-national and multi-disciplinary experiments was conducted between 2000-2002 to identify and measure key ocean boundary characteristics. The frequency range of interest was nominally 500-5000 Hz with the main focus on the seabed, which is generally considered as the boundary of greatest importance and least understood. Two of the experiments were conducted in the Mediterranean in the Strait of Sicily and one experiment in the North Atlantic with sites on the outer New Jersey Shelf (STRATAFORM area) and on the Scotian Shelf. Measurements included seabed reflection, seabed, surface, and biologic scattering, propagation, reverberation, and ambient noise along with supporting oceanographic, geologic, and geophysical data. This paper is primarily intended to provide an overview of the experiments and the strategies that linked the various measurements together, with detailed experiment results contained in various papers in this volume and other sources

21世纪中国历史地理学发展的思考

本文在回顾中国历史与近50年来取得的巨大成就的基础上,结合当今地球系统科学、地理科学的发展趋势以及国际全球变化与可持续发展研究的最新动向,提出了新世纪中国历史地理学研究应以收集、发掘人类文明演进的地理证据,分析历史上人地交互作用的时空特征为核心,以探寻当今地理学历史渊源人类适应环境变化模式的历史证据为目标,以文献分析、野外调查、考古发掘等传统方法与现代实验技术、空间信息技术的集成为手段,以编制5000年来华夏故土嬗变与文明演进的历史图谱为主要平台的发展新思路,并认为中国历史地理学在国际全球变化与可持续发展

Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.

Highly 3,4-selective living polymerization of isoprene with rare earth metal fluorenyl N-heterocyclic carbene precursors

Fluorenyl modified N-heterocyclic carbene ligated rare earth metal bis(alkyl) complexes, (Flu-NHC)Ln(CH2SiMe3)2 (Flu-NHC = (C13H8CH2CH2(NCHCCHN)C6H2Me3-2,4,6); Ln = Sc (1a); Ln = Y (1b); Ln = Ho (1c); Ln = Lit (1d)), were synthesized and fully characterized by NMR and X-ray diffraction analyses. Complexes Ib-d with the activation of (AlBu3)-Bu-i and [Ph3C][B(C6F5)4] exhibited high activity, medium syndio-but remarkably high 3,4-regio-selectivity, and the unprecedented livingness for the polymerization of isoprene. Such distinguished catalytic performances could be maintained under various monomer-to-initiator ratios (500-5000) and broad polymerization temperatures (25-80 degrees C).

温度敏感性PNIPAM-b-PZLL-b-mPEG三嵌段共聚物的合成与自组装研究

通过大分子引发剂引发ε-苄氧羰基-L-赖氨酸-N-羧酸酐(Lys-NCA)开环聚合和大分子缩合的方法合成了聚(N-异丙基丙烯酰胺)-b-聚(ε-苄氧羰基-L-赖氨酸)-b-聚乙二醇单甲醚三嵌段共聚物(PNIPAM-b-PZLL-b-mPEG).用GPC和1H-NMR对其结构进行了表征.用芘荧光探针法证明了该三嵌段聚合物形成胶束的性质并测定了临界胶束浓度(CMC).动态光散射(DLS)研究表明,在固定PNIPAM-b-PZLL链段长度的情况下,mPEG分子量为2000时,胶束在温度高于临界溶解温度(LCST)时发生聚集,mPEG分子量为5000时,胶束在LCST以上没有发生聚集.

SYNTHESIS AND CHARACTERIZATION OF A CROSSLINKING POLYETHYLENIMINE AS SMART GENE CARRIER AND EFFECTS OF PEGYLATION DEGREE

A smart biodegradable cationic polymer (CBA-PEI) based on the disulfide bond-containing cross-linker cystamine bisacrylamide (CBA) and low molecular weight branched polyethylenimine (1800-Da, PEI1800) was successfully synthesized by Michael addition reaction in our recent study. Furthermore, a series of copolymers (CBA-PEI-PEG) with different PEGylation degree were obtained by the mPEG-SPA (5000-Da) reacting with CBA-PEI at various weight ratios directly. The molecular structures of the resulting polymers CBA-PEI and CBA-PEI-PEG were evaluated by nuclear magnetic resonance spectroscopy (H-1-NMR) and capillary viscosity measurements, all of which had successfully verified formation of the copolymers. The polymer/DNA complexes based on CBA-PEI and CBA-PEI-PEG were measured by dynamic light scattering and gel retardation assay. The results showed that the particle size and zeta potential of complexes were reduced with increasing amount of PEG grafting, even no particle formation. The particle size of CBA-PEI/DNA complexes was in range of 103.1 to 129.1 nm, and the zeta potential was in range of 14.2 to 24.3 mV above the 2:1 weight ratio. In the same measure condition, the particle size of CBA-PEI-PEG complexes was reduced to a range of 32.2 to 55 nm, and the zeta potential was in range of 9.3 to 13.8 mV at the 2:1 weight ratio.

Preparation and chracaterization of novel graft copolymers of LLDPE

A series of novel fluorine surfactants, a, b, c, d, e and their acrylates, A, 13, C, D and E, were synthesized via poly( ethylene oxide) ( PEG) ( 200, 600, 1000, 2000, 5000) and perfluorooctane poly (ethylene oxide) ether as the main starting materials. Their chemical structures were characterized by means of FTIR and H-1 NMR. The surface activity and surface tension( y) of surfactants a, b, c, d and e were evaluated by maximum bubble pressure method. Surfactants A, 13, C, D and E were adopted as the grafting monomers of linear low density polyethere( LLDPE), and grafting reaction was carried out by melt reactive extrusion procedure. Their surface properties were characterized with measuring contact angle and XPS. It was found that the hydrophilic property of the graft copolymers was better than the palin LLDPE. Thermal properties of graft copolymers were studied by DSC. It was found that their crystalline temperatures of graft copolymers were faster than that of the plain LLDPE.

Study of the synthesis, crystallization, and morphology of poly(ethylene glycol)-poly(is an element of-caprolactone) diblock copolymers

Poly(ethylene glycol) -poly(epsilon-caprolactone) diblock copolymers PEG-PCL were synthesized by ring-opening polymerization of c-caprolactone using monomethoxy poly(ethylene glycol) as the macroinitiator and calcium ammoniate as the catalyst. Obvious mutual influence between PEG and PCL crystallization was studied by altering the relative block length. Fixing the length of the PEG block (M-n = 5000) and increasing the length of the PCL block, the crystallization temperature of the PCL block rose gradually from I to about 35 degreesC while that of the PEG block dropped from 36 to -6.6 degreesC. Meanwhile, the melting temperature of the PCL block went up from 30 to 60 degreesC, while that of the PEG block declined from 60 to 41 degreesC. If the PCL block was longer than the PEG block, the former would crystallize first when cooling from a molten state and led to obviously imperfect crystallization of PEG and vice versa. And they both crystallized at the same temperature, if their weight fractions were equal. We found that the PEG block could still crystallize at -6.6 degreesC even when its weight fraction is only 14%. A unique morphology of concentric spherulites was observed for PEG5000-PCL5000.

Highly efficient pure-white-light-emitting diodes from a single polymer: Polyfluorene with naphthalimide moieties

Light-emitting diodes exhibiting efficient pure-white-light electroluminescence have been successfully developed by using a single polymer: polyfluorene derivatives with 1,8-naphthalimide chromophores chemically doped onto the polyfluorene backbones. By adjusting the emission wavelength of the 1,8-naphthalimide components and optimizing the relative content of 1,8-naphthalimide derivatives in the resulting polymers, white-light electroluminescence from a single polymer, as opposed to a polymer blend, has been obtained in a device with a configuration of indium tin oxide/poly(3,4-ethyleiledioxythiophene)(50 nm)/polymer(80 nm)/Ca(10 nm)/Al(100 nm). The device exhibits Commission Internationale de I'Eclairage coordinates of (0.32,0.36), a maximum brightness of 11900 cd m(-2), a current efficiency of 3.8 cd A(-1), a power efficiency of 2.0 lm W-1. an external quantum efficiency of 1.50 %, and quite stable color coordinates at different driving voltages, even at high luminances of over 5000 cd m(-2).

Composition dependence of the crystallization behavior and morphology of the poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer

The crystallization behavior and morphology of the crystalline-crystalline poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer (PEO-b-PCL) was studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), and hot-stage polarized optical microscope (POM). The mutual effects between the PEO and PCL blocks were significant, leading to the obvious composition dependence of the crystallization behavior and morphology of PEO-b-PCL. In this study, the PEO block length was fixed (M-n = 5000) and the weight ratio of PCL/PEO was tailored by changing the PCL block length. Both blocks could crystallize in PEO-b-PCL with the PCL weight fraction (WFPCL) of 0.23-0.87. For the sample with the WFPCL of 0.36 or less, the PEO block crystallized first, resulting in the obvious confinement of the PCL block and vice versa for the sample with WFPCL of 0.43 or more. With increasing WFPCL, the crystallinity of PEO reduced continuously while the variation of the PCL crystallinity exhibited a maximum. The long period of PEO-b-PCL increased with increasing WFPCL from 0.16 to 0.50 but then decreased with the further increase of WFPCL due to the interaction of the respective variation of the thicknesses of the PEO and PCL crystalline lamellae.

Influence of crystal structure on the luminescence properties of bismuth(III), europium(III) and dysprosium(III) in Y2SiO5

The luminescence properties of Bi3+, EU(3+), Dy3+ and energy transfer from Bi3+ to Dy3+ and EU(3+) have been studied in two modifications of Y2SiO5 (low-temperature X(1) type and high-temperature X(2) type) and discussed in relation to their crystal structures. The Bi3+ ion luminesces in the blue region of the spectrum in X(1)-Y2SiO5 but in the UV region in X(2)-Y2SiO5. Two obviously different luminescent centres have been observed for Bi3+ and Eu3+ ill X(1)-Y2SiO5, but only one has been seen in X(2)-Y2SiO5. The Stokes shift (9200 cm(-1)) for Bi3+ in X(1)-Y2SiO5 is much larger than that (5000 cm(-1)) in X(2)-Y2SiO5. This suggests that the host lattice is more rigid in X(2)-Y2SiO5 than in X(1)-Y2SiO5. As a result, the Bi3+, EU(3+) and Dy3+ ions show higher emission intensity in the former than in the latter type. X(1)-Y2SiO5 is more suitable for Bi3+ --> EU(3+) energy transfer and X(2)-Y2SiO5 is more suitable for Bi3+ --> Dy3+ energy transfer.

SIMULTANEOUS DETERMINATION OF GUANINE, URIC-ACID, HYPOXANTHINE AND XANTHINE IN HUMAN PLASMA BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH AMPEROMETRIC DETECTION

A reversed-phase high-performance liquid chromatographic method with amperometric detection is described for the separation and quantification of uric acid, guanine, hypoxanthine and xanthine. The isocratic separation of a standard mixture of the compounds was achieved in 5 min on a Spherisorb 5 C-18 reversed-phase column, with a mobile phase of NaH2PO4 (300 mmol dm(-3) pH 3.0)-methanol-acetonitrile-tetrahydrofuran (97.8 + 0.5 + 1.5 + 0.2). Uric acid, guanine, hypoxanthine and xanthine were completely separated, with detection limits in the range 2-20 pmol per injection. The effect of pH and the composition of the mobile phase on the separation are described. The hydrodynamic voltammograms of these compounds were recorded at a glassy carbon electrode. The linear range of the calibration graph for each compound was: uric acid; 1-5000 mu mol dm(-3); guanine, 0.5-2000 mu mol dm(-3); hypoxanthine, 0.1-500 mu mol dm(-3) and xanthine, 0.5-5000 mu mol dm(-3). The within- and between-day precision was good. The uric acid and hypoxanthine content in human plasma was measured using the proposed method. Good recoveries of uric acid (97.9-103%), hypoxanthine (98.0-99.2%), guanine (96.0-98.3%) and xanthine (96.0-102%) were obtained from human plasma. The results of electrochemical detection were in good agreement with those of UV detection.

共价氢化物发生-光度分析法高选择性的研究与应用——Ⅰ.锗、砷、硒共价氢化物性质初探及其分别测定时其它氢化物干扰的消除

本文采用氢化物发生-银溶胶光度分析法探讨了GeH_4、AsH_3和H_2Se的性质,并利用共价氢化物气体分离柱分别建立了测定锗、砷时消除其它可生成氢化物元素干扰的简便、高效方法。测定1.0μg Ge(Ⅳ),5000μg As(Ⅴ)、Bi(Ⅱ)、Pb(Ⅰ)、1000μg Sb(Ⅱ)、Sn(Ⅰ)、500μg As(Ⅱ)和100μg Se(Ⅳ)、Sn(Ⅳ),Te(Ⅳ)不产生干扰。对砷的测定,其它共价氢化物元素的允许倍数分别为:Sb(Ⅱ)(5000)、Pb(Ⅰ)(5000)、Bi(Ⅱ)(5000)、Sn(Ⅰ)(1000)、Se(Ⅳ)(100)、Te(Ⅳ)(100)和Ge(Ⅳ)(15)。

薄膜CdS/Cu_2S太阳电池寿命与温度关系的探讨

对薄膜CdS/Cu_2S光伏器件稳定性的研究表明,温度对电池寿命的影响是不可忽视的因素。J·Meikin指出,在40℃下对CdS/Cu_2S电池加热5000小时,Ⅰ_(sc)仅下降1％;对于包封电池,K.Boer得出,在60℃下加热两年电池性能没有发生衰变的结论。 我们通过对CdS/Cu_2S太阳电池的加热寿命试验,寻求器件寿命与温度间的关系,并用