Synthesis and characterization of novel biodegradable poly(carbonate ester)s with photolabile protecting groups

Novel biodegradable poly(carbonate ester)s with photolabile protecting groups were synthesized by ring-opening copolymerization Of L-lactide (LA) with 5-methyl-5-(2-nitro-benzoxycarbonyl)-1,3-dioxan-2-one (MNC) with diethyl zinc (Et2Zn) as catalyst. The poly(L-lactide-co-5-methyl-5-carboxyl-1,3-dioxan-2-one) (P(LA-co-MCC)) was obtained by UV irradiation Of poly(L-lactide acid-co-5-methyl-5-(2-nitro-benzoxycarbonyl)-1,3-dioxan-2-one) (P(LA-co-MNC)) to remove the protective 2-nitrobenzyl group.

Preparation of Prussian blue@Pt nanoparticles/carbon nanotubes composite material for efficient determination of H2O2

In this study, the fabrication of an efficient amperometric hydrogen peroxide sensor with favorable properties is presented. Prussian blue (PB) was catalytically synthesized by Pt nanoparticles (Pt-nano) from ferric ferricyanide aqueous solution to form PB@Pt-nano hybrid, and it was confirmed by transmission electron microscope (TEM) and optical spectra. The electrochemical behavior of PB@Pt-nano was highly improved through its integration with poly(diallyldimethylammonium chloride) modified carbon nanotubes (PCNTs).

Synthesis and characterization of monodisperse spherical SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

Spherical SiO2 particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Ln = Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO2@RE2O3 (RE = rare earth elements) and SiO2@Gd2O3:Ln(3+) (Eu3+, Tb3+, Dy3+, Sm3+, Er3+, Ho3+) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles).

Synthesis and properties of a novel isomeric polyimide/SiO2 hybrid material

A novel isomeric polyimide/SiO2 hybrid material was successfully prepared through sol-gel technique, and its structure, thermal properties and nano-indenter properties were investigated. First, 3-[(4-phenylethynyl)phthalimide]propyl triethoxysilane (PEIPTES) was successfully synthesized, its structure was characterized by elemental analysis, FT-IR and C-13 NMR. The researches on solubility and thermal properties of PEIPTES show that it can be used for modifying nano-SiO2 precursor. Nano-SiO2 precursor was synthesized by tetraethoxysilane (TECS) through sol-gel technique. Then the PEIPTES solution and the nano-SiO2 precursor were mixed for 6 h to let the PEIPTES molecules react with the nano-SiO2 precursor, and modified nano-SiO2 precursor was obtained. The modified reaction was confirmed by the analyses of FT-IR. At last, isomeric polyimide/SiO2 hybrid material was produced by using isomeric polyimide resin solution and the modified nano-SiO2 precursor after heat treatment process. The structure analysis by SEM indicated that SiO2 particles dispersed in isomeric polyimide matrix homogeneously with nanoscale. Thermogravimetric analyzer, dynamic mechanical thermal analyzer and nano-indenter XP was employed to detect the properties of the materials, the results demonstrated that isomeric polyimide/SiO2 hybrid material has much better thermal properties and nano-indenter properties than those of isomeric polyimide.

Fabrication and characterization of self-doped poly (aniline-co-anthranilic acid) nanorods in bundles

Poly (aniline-co-anthranilic acid) (PANANA) nanorods in bundles was prepared successfully in an alcohol/aqueous media without assistance of an), other kinds of acids. Anthranilic acid played all roles of monomer, acid-media provider, and dopant in the reaction system, and ammonium persulfate (APS) served as the oxidant. The morphologies of PANANA nanorods in bundles were investigated by scanning electron microscopy (SEM). Influences of the monomer molar ratio on the resulting morphology were investigated. Moreover the formation mechanism of the nanostructured copolymer was proposed. FT-IR. UV-vis and X-ray diffraction (XRD) measurements were used to confirm the molecular and electrical structure of the self-doped PANANA. The intrinsic properties, such as conductivity, electrochemical redox activity and room-temperature solubility of the resulting copolymer were explored.

Investigation on preparation and fluorescence properties of oxy-fluoride glass co-doped with Er3+ and Yb3+

The glass sample based on the composition of 45PbF(2)-45GeO(2)-10WO(3) co-doped with Yb3+/Er3+ was prepared by the fusion method in two steps: melted at 950 degreesC for 20 similar to 25 min then annealed at 380 degreesC for 4 h. Through the V-prism it is found that the refractive index of host glass and the sample are 1.517 and 1.65 respectively. The transmittance was observed by using the ultraviolet-visible-infrared spectrometer in the wavelength range from 0.35 to 2.5mum. The transmittaitce of the host glass is beyond 73%. That of the sample is beyond 50% and there are characteristic absorption peaks of rare-earth ions. The emission spectrum was measured by using the Hitachi F-4500 fluorescent spectrometer pumped by 980 nm semiconductor laser. There are a strong emission peak at 530 nm and a weak peak at 650 nm.

偏硅酸镉的自激活发光

利用高温固相法合成了一种具有自激活发光行为的CdSiO3基质.对样品进行了X射线衍射分析和光谱分析.光谱分析结果表明,在偏硅酸镉的发射光谱中存在三个自激活发光峰,它们分别位于380,467和560nm处,另外,通过热释光谱技术讨论了偏硅酸镉中的缺陷及相关机理.在热释光谱中有两个明显的热释峰,分别位于448和563K,它们的陷阱深度分别为0 58和0 61eV,表明了在偏硅酸镉中存在着不同的陷阱,这些陷阱的存在导致了偏硅酸镉的自激活发光.

Precursor induced synthesis of hierarchical nanostructured ZnO

As-synthesized ZnO nanostructures with a bladed bundle-like architecture have been fabricated from a flower-like precursor ZnO (.) 0.33ZnBr(2) (.) 1.74H(2)O via a mechanism of dissolution - recrystallization. Experimental conditions, such as initial reactants and reaction time, are examined. The results show that no bladed bundle-like ZnO hierarchical nanostructures can be obtained by using the same molar amount of other zinc salts, such as ZnBr2, instead of the flower-like ZnO (.) 0.33ZnBr(2) (.) 1.74H(2)O precursor, and keeping other conditions unchanged. The products were characterized by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The ZnO nanostructures are mainly composed of nanowires with a diameter around 40 - 50 nm and length up to 1.5 - 2.5 mu m. Meanwhile, ZnO nanoflakes with a thickness of about 4 - 5 nm attached to the surface of ZnO nanowires with a preferred radially aligned orientation. Furthermore, the photoluminescence (PL) measurements exhibited the unique white-light-emitting characteristic of hierarchical ZnO nanostructures. The emission spectra cover the whole visible region from 380 to 700 nm.

Co-electrospun poly(lactide-co-glycolide), gelatin, and elastin blends for tissue engineering scaffolds

In this study, we describe composite scaffolds composed of synthetic and natural materials with physicochemical properties suitable for tissue engineering applications. Fibrous scaffolds were co-electrospun from a blend of a synthetic biodegradable polymer (poly(lactic-co-glycolic acid), PLGA, 10% solution) and two natural proteins, gelatin (denatured collagen, 8% solution) and (x-elastin (20% solution) at ratios of 3:1:2 and 2:2:2 (v/v/v). The resulting PLGA-gelatin-elastin (PGE) fibers were homogeneous in appearance with an average diameter of 380 80 mn, which was considerably smaller than fibers made under identical conditions from the starting materials (PLGA, 780 +/- 200 nm; gelatin, 447 +/- 1.23 nm; elastin, 1060 170 nm). Upon hydration, PGE fibers swelled to an average fiber diameter of 963 +/- 132 nm, but did not disintegrate. Importantly, PGE scaffolds were stable in an aqueous environment without crosslinking, and were more elastic than those made of pure elastin fibers. To investigate the cytocompatibility of PGE, we cultured H9c2 rat cardiac myoblasts and rat bone marrow stromal cells (BMSCs) on fibrous PGE scaffolds. We found that myoblasts grew equally as well or slightly better on the scaffolds than on tissue-culture plastic. Microscopic evaluation confirmed that myoblasts reached confluence on the scaffold surfaces while simultaneously growing into the scaffolds.

Dependence of crystal field splitting of 5d levels on hosts in the halide crystals

The crystal field splitting of 5d level of EU2+ and Ce3+ in halide crystals has been studied. Our results indicate that the 10Dq splitting can be directly related to the homopolar part of average energy gap, the coordination number of central (doped) ion, the charge of neighboring anions and bond ionicity between central ion to nearest anions. A relation between the 10Dq splitting and the above mentioned factors is presented. Our calculated results are in reasonable agreement with diverse experiments.

甲醇对炭载铂和四羧基酞菁钴催化氧还原动力学的影响

运用旋转圆盘电极技术和线性扫描伏安方法研究比较了甲醇对炭载铂(Pt/C)和800℃热处理的炭载四羧基酞菁钴(CoPcTc/C)催化氧还原动力学的影响.结果表明,对于Pt/C催化剂,在大于0.64V和小于0.18V(vsSCE)的电位范围,甲醇的氧化和氧的还原互不影响,而在其它电位范围,甲醇使Pt/C催化氧还原的性能严重降低.对于800℃热处理的CoPcTc/C,在整个电位范围内,甲醇的存在对氧还原都没有影响,是一种活性较高、耐甲醇能力强的氧还原电催化剂.

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4 '-bipy)(H2O)4](4-abs)2 center dot nH(2)O (4,4 '-bipy=4,4 '-Bipyridine; 4-abs=4-aminobenzenesulfonate) (M=Co, n=1; M=Mn, n=2)

Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

Cupric hexacyanoferrate nanoparticle modified carbon ceramic composite electrodes

Graphite powder-supported cupric hexacyanoferrate (CuHCF) nanoparticles were dispersed into methyltrimethoxysilane based gels to produce a conducting carbon ceramic Composite, which was used as electrode material to fabricate surface- renewable CuHCF-modified electrodes. Electrochemical behavior of the CuHCF-modifled carbon ceramic composite electrodes was characterized using cyclic and square-wave voltammetry. Cyclic voltammograms at various scan rates indicated that peak currents were surface-confined at low scan rates. In the presence of glutathione, a clear electrocatalytic response was observed at the CuHCF-modified composite electrodes. In addition, the electrodes exhibited a distinct advantage of reproducible surface-renewal by simple mechanical polishing on emery paper, as well as ease of preparation, and good chemical and mechanical stability in a flowing stream.

发光薄膜的制备及应用

与传统的发光粉制作的显示屏相比 ,发光薄膜在对比度、分辨率、热传导、均匀性、与基底的附着性、释气速率等方面都显示出较强的优越性。因此 ,作为功能材料 ,发光薄膜在诸如阴极射线管 (CRTs)、电致发光显示 (ELDs)及场发射显示 (FEDs)等平板显示领域中有着广阔的应用前景。发光薄膜的制备方法有许多种 ,包括溅射法、金属有机物化学汽相沉积法、溶胶 凝胶法、脉冲激光沉积法、喷雾热解法、蒸镀法等。本文系统地对这些发光薄膜的制备方法及其应用情况作以简单的介绍 ,最后对发光薄膜的发展趋势进行了展望。