Neodymium oxide co-catalyzed melt free radical grafting of maleic anhydride onto co-polypropylene by reactive extrusion

Rare earth oxide, neodymium oxide (Nd2O3), CO-catalyzed melt grafting of maleic anhydride (MAH) onto co-polypropylene (co-PP) in the presence of dicumyl peroxide (DCP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd2O3 as a coagent leads to an enhancement in both MFR and the grafting degree of MAH, along with a simultaneous decrease in the gel content. When the Nd2O3 concentration is 6.0 mmol%, the increment of the grafting degree of MAH maximally is up to about 20% compared with the related system without adding Nd2O3, and the gel content decreases simultaneously to a very low level of about 3%. Attenuated total reflection FTIR (ATR-FTIR) indicates that the gel in the graft copolymers mainly arise from the cross-linking reaction between ethylene units of co-PP. A reasonable reaction mechanism has been put forward on the basis of our experimental results and other mechanisms reported in the literature. We also tentatively explain above results by means of synergistic effect between DCP and Nd2O3, which causes a higher concentration of the macroradical, in particular the tertiary macroradical.

钒取代Keggin型杂多酸的多层组装和电催化性能研究

用层层组装的方法在 4 -氨基苯甲酸预修饰的玻碳电极上交替沉积过渡金属钒取代的杂多酸H3 PW6V6O6- 4 0 (简称 PW6V6)和联吡啶锇取代的聚乙烯吡啶 (QPVP-Os) .用表面等离子体共振 (SPR)技术和循环伏安 (CV)法对多层膜进行了表征 .结果表明 ,多层膜的生长均匀 ,平均厚度为 2 .88nm.还研究了多层膜对亚硝酸根 (NO- 2 )和溴酸根 (Br O- 3 )的催化还原活性.

Hybrid luminescent films obtained by covalent anchoring terbium complex to silica-based network

New monomer N-(4-carboxyphenyl)-NL-(propyltriethoxysilyl)urea (1) which acts as both a ligand for Th3+ ion and a sol-gel precursor has been synthesized and characterized by H-1 NMR, and MS. Hybrid luminescent thin films consisting of organoterbium covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. Strong line emission of Tb3+ ion was observed from the hybrid luminescent films under UV excitation.

蓝紫色ZnO-Al_2O_3-SiO_2长余辉陶瓷

通过高温固相法首次合成并报道了兰紫色ZnO Al2O3 SiO2长余辉陶瓷,系统地研究了其发光和缺陷性质。在强度0.6mW·cm-2,主峰254nm的UVP紫外灯下激发15min,然后关闭激发源,样品发射兰紫色长余辉。撤去激发源以后5s,余辉初始强度为230mcd·m-2,色坐标为(0.1292,0.0984)。暗视场中,8h以后余辉仍然肉眼可辨。样品的紫外可见发射和不同时间的余辉发射光谱显示:荧光发射位于390nm,来源于基质的自致发光;而余辉有两个发射峰,主峰位于390nm,肩峰位于520nm。这表明样品中存在两种余辉发射中心。由余辉衰减曲线可以看出,这两种余辉发光都由一个快过程和一个慢过程组成。其中,慢过程决定了材料的长余辉时间。从时间依赖的余辉强度倒数曲线可以看出,余辉强度与时间成反比,这表明余辉发光的机理为电子空穴复合过程。热释光谱显示:样品分别在92和250℃附近出现两个宽的热释峰,说明材料中至少存在两种具有不同陷阱深度的电子或空穴缺陷中心。

Sol-gel deposition of calcium silicate red-emitting luminescent films doped with Eu3+

Eu3+-activated calcium silicate (CaO-SiO2:Eu3+) luminescent films were prepared by the sol-gel method. The structural evolution of the film was studied by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the luminescence properties of the phosphor films were investigated as a function of heat treatment temperature. The XRD study indicates that a kilchoanite phase forms in the film sintered at 800 degreesC, which is different from that in gel powder treated under the same conditions. The SEM results show that the film thickness decreases and the particles in the film become smaller with increasing heat treatment temperature. The CaO-SiO2:Eu film shows the characteristic emission of Eu3+ under UV excitation, with the Eu3+ D-5(0)-->F-7(2) band (616 nm) being the most prominent. A large difference in the Eu3+ lifetime is observed between the film samples treated at 500 and 700 degreesC (or above). Concentration quenching occurs when the Eu3+ doping concentration is above 6 mol% of Ca2+ in the film.

Calculation of chemical bond parameters in RBa2Cu4O8(R = Dy,Ho,Er,Tm,Yb) and Y2Ba4Cu7O14.3

Chemical bond parameters in RBa2Cu4O8(R = Dy, Ho, Er, Tm, Yb) and Y2Ba4Cu7O14.3 were calculated by using complex chemical bond theory. The results indicated that the bond covalency in CuO chain was larger than that in CuO2 plane. For metal atoms, the bond covalency of five coordinated case was larger than that of six coordinated case.

RBa_2Cu_4O_8(R=Dy,Ho,Er,Tm,Yb)和Y_2Ba_4Cu_7O_(14.3)的化学键参数计算

使用复杂晶体上化学键理论计算了 RBa2 Cu4 O8(R=Dy,Ho,Er,Tm ,Yb)和 Y2 Ba4 Cu7O14 .3 的化学键参数 .结果表明 ,Cu O链上的 Cu O键共价性大于它们在 Cu O2 面的共价性 .当金属元素与氧形成五配位时 ,其共价性的数值大于这些元素在六配位时的情形

The site symmetry of Eu3+ in ZnS : Eu nanoparticle

Nanosized ZnS doped with different concentrations of Eu3+ were prepared and analyzed by x-ray diffraction technique. The experimental results show that ZnS belongs to the cubic structure. From the photoluminescence (PL) emission spectra, it can be seen that the ratio of the emission intensity of Eu3+ 616 nm to that at 590 nm increases as the increasing of Eu3+. This phenomenon reveals that the site symmetry of Eu3+ reduces as the increasing of Eu3+.

Chemiluminescent determination of glucose with a modified carbon paste electrode

A flow injection analysis detection method for glucose is presented which is based on the oxidation of glucose by glucose oxidase followed by chemiluminescent detection of hydrogen peroxide. Both glucose oxidase and hematin, a chemiluminescent reaction catalyst, were bulk-immobilized conveniently by direct mixing with carbon paste, which allows renewal of the electrode surface by simply polishing or cutting to expose a new and fully active surface in the case of fouling. Luminol in reagent solution passed through the flow cell and reacted with hydrogen peroxide produced by the enzyme reactor in the presence of the catalyst to yield light. An applied potential of -0.4 V avoided the electrode fouling effectively. The log-log plot of the emitted light intensity vs glucose concentration was linear over the range of 1-100 mmol L-1 with a correlation coefficient of 0.992. Application of this method to other chemiluminescent and bioluminescent systems is suggested. (C) 1999 Academic Press.

[Ni(C10H8N2)(3)](2)[V4O12].11H(2)O

The crystal structure of the title compound, bis[tris(2,2'-bipyridyl-N,N')nickel(II)] cyclo-tetravanadate undecahydrate, contains a centrosymmetric [V4O12](4-) anion, which has an eight-membered ring structure formed by four VO4 tetrahedra sharing vertices, and two complex cations containing octahedrally-coordinated Ni-II ions. The anion and coordinated Ni-II ions are isolated and make up anion and cation layers, respectively. The Ni-N distances range from 2.077(3) to 2.112(2)Angstrom and the V-O distances range from 1.621(2) to 1.803(2)Angstrom.

Role of Lithium in Multicomponent Oxide Catalysts for Oxidative Coupling of Methane

The effect of Li content in a series of multicomponent oxides LixLa0.5Ti0.5 For methane oxidative coupling has been studied. The catalytic activities of LiLa0.5Ti0.5 catalyst before and after washing with boiling water have been compared. The surface and

锂在甲烷氧化偶联多元氧化物催化剂中的作用

考察了不同Li含量对LixLa0．5Ti0．5系氧化物催化剂的甲烷氧化偶联催化性能的影响；比较了水洗前后LiLa0．5Ti0．5氧化物催化剂的催化活性，并通过XRD、IR、XPS和BET等方法时催化剂进行表征。确认了Li在含稀土、过渡金属多元氧化物中的作用。其中，表面Li的作用是缩小催化剂的比表面积，覆盖表面深度氧化活性位，提高C2选择性；体相Li的作用是部分取代Ti3+进入LaTiO3晶格形成LaTi1-yLiyO3-λ活性相，产生甲烷氧化偶联Li+－O-－Ti3+缺陷簇。（注：LixLa0．5Ti0．5和LiLa0．5Ti0．5表示该系列氧化物催化剂制备时的各金属元素的配比。用来表示催化剂的名称，并不表示实际存在的物相，以下类同，下面出现时，不再加以说明。

THE CLEAVAGE REACTION OF THE MO-MO TRIPLE BOND - THE CRYSTAL-STRUCTURES OF MOLYBDENUM COMPLEXES [CPMO(CO)(2)(C(5)H(4)NS)], [CPMO(CO)(2)(C(9)H(6)NS)]O=PPH(3) AND [CPMO(CO)(2)(S(2)CNME(2)]

The reactions of [Cp2Mo2(CO)4] (1) with 2,2'-dipyridyl disulphide (C5H4NS-)2, 8,8'-diquinolyl disulphide (C9H6NS-)2 and tetramethyl thiuram disulphide (Me2NC(S)S-)2 in toluene solution resulted in the cleavage of the Mo-Mo triple bond to yield molybdenum complexes [CpMo(CO)2(C5H4NS)] (2), [CpMo(CO)2(C9H6NS)] (3) and [CpMo(CO)2(S2CNMe2)] (4), respectively. The molecular structures of 2, 3 . O=PPh3 and 4 were determined by X-ray diffraction studies. Crystals of 2 are monoclinic, space group P2(1)/n, with Z = 4, in a unit cell of dimensions a = 6.448(1), b = 12.616(2), c = 14.772(2) angstrom, beta = 92.85(1)-degrees. The structure was refined to R = 0.028 and R(w) = 0.039 for 1357 observed reflections. Crystals of 3 . O=PPh3 are triclinic, space group P1BAR, with Z = 2, in a unit cell of dimensions a = 11.351(3), b = 13.409(3), c = 9.895(2) angstrom, alpha = 94.59(2), beta = 90.35(2), gamma = 78.07(2)-degrees. The structure was refined to R = 0.033 and R(w) = 0.037 for 3260 observed reflections. Crystals of 4 are monoclinic, space group P2(1)/a and Z = 4 with a = 12.468(5), b = 7.637(2), c = 13.135(4) angstrom, beta = 96.62(3). The structure was refined to R = 0.032 and R(w) = 0.042 for 1698 observed reflections. Each of complexes 2-4 contains a cyclopentadienyl ligand, a cis pair of carbonyls and a chelate ligand (S,N donor or S,S donor). All the compounds have distorted square-pyramid structures.

SYNTHESIS AND CRYSTAL-STRUCTURE OF HETEROPOLY MOLYBDOSILICIC LANTHANIDE K10H3[PR(SIMO11O39)2].18H2O

The intensity data of the title complex were collected at a low temperature of -90-degrees-C. The compound crystallizes in the monoclinic space group P2(1)/n, a = 17.504(2), b = 27.323 (5), c = 21.616(4) angstrom, beta = 104.49 (2)degrees, Z = 4. The structure was solved by Patterson and Fourier techniques and refined by least-squares to an R = 0.088 for 8320 independent reflections. The central Pr ion is bonded to eight oxygen atoms from two molybdosilicic heteropoly ligands to form a square antiprism. The Pr-O average distance is 2.44 (2) angstrom. Both molybdosilicic heteropoly ligands are of a defective alpha-Keggin structure.