Relationship between charge transfer energies of Yb3+ and Sm3+ and crystal environmental factor

Relationship between charge transfer energies E-CT of Yb3+ and Sm3+ and environmental factors h(e) in various crystals was investigated using a dielectric chemical bond method. Both results show that they have an exponential relation E-CT = A+B exp(-kh(e)), but the exponential factors are different, which indicates that the interaction between the rare earth ions and environment is connected with the kind of rare earth ion. This result provides a method of determining charge transfer energies of Yb3+ and Sm3+ from a crystal structure.

Novel proton exchange membranes based on water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)]

Novel water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBIs) were synthesized from 6,6'-disulfonic-4,4'-binaphthy]-1,1',8,8'-tetracarboxylic dianhydride (SBTDA) and various aromatic ether tetraamines. The resulting polymers with IEC in the range of 2.17-2.87 mequiv g(-1) have a combination of desired properties such as high solubility in common organic solvents, film-forming ability, and excellent thermal and mechanical properties. Flexible and tough membranes, obtained by casting from m-cresol solution, had tensile strength, elongation at break, and tensile modulus values in the range of 87.6-98.4 MPa, 35.8-52.8%, and 0.94-1.07 GPa. SPBIBI membranes with a high degree of sulfonation displayed high proton conductivity and a good resistance to water swelling as well. SPBIBI-b with IEC of 2.80 mequiv g(-1) displayed the conductivity of 1.74 x 10(-1) S cm(-1) at 100 degrees C, which was comparable to that of Nafion (R) 117 (1.78 x 10(-1) S cm(-1), at 100 degrees C).

Nanoelectrocatalyst based on high-density Au/Pt hybrid nanoparticles supported on a silica nanosphere

A high-efficiency nanoelectrocatalyst based on high-density Au/Pt hybrid nanoparticles supported on a silica nanosphere (Au-Pt/SiO2) has been prepared by a facile wet chemical method. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy are employed to characterize the obtained Au-Pt/SiO2. It was found that each hybrid nanosphere is composed of high-density small Au/Pt hybrid nanoparticles with rough surfaces. These small Au/Pt hybrid nanoparticles interconnect and form a porous nanostructure, which provides highly accessible activity sites, as required for high electrocatalytic activity. We suggest that the particular morphology of the AuPt/SiO2 may be the reason for the high catalytic activity. Thus, this hybrid nanomaterial may find a potential application in fuel cells.

Investigations on the adsorption behavior of Neutral Red on mercaptoethane sulfonate protected gold nanoparticles

A detailed investigation on the adsorption behavior of Neutral Red (NR) molecules on mercaptoethane sulfonate-monolayer protected gold clusters (MES-MPCs) has been conducted by the spectroscopic method. It is found that cationic NR molecules are adsorbed on the negatively charged MPCs surfaces via electrostatic attractive forces. The absorption study shows that the optical properties of NR molecules are significantly influenced upon the adsorption. Based on the electrostatic adsorption nature and the excellent stability of MES-MPCs against the electrolytes, this association can be released by the addition of electrolyte salts, which can be monitored by both absorption and fluorescence spectroscopy. In addition, dication Ca2+ is found to be more effective in the release of NR than univalent Na+. Moreover, the MES-MPCs exert energy transfer quenching of NR fluorescence by both static and dynamic quenching. However, static quenching seems to be the dominating quenching mechanism. Furthermore, this energy transfer quenching exhibits strong dependence of Au core size, and 5.0 nm MPCs show stronger ability in quenching the NR fluorescence than that of 2.7 nm MPCs.

The microstructure and mechanical properties of Mg-8Zn-8Al-4RE magnesium alloy

The Mg-8Zn-8Al-4RE (RE = mischmetal, mass%) magnesium alloy was prepared by using casting method. The microstructure and mechanical properties of as-cast alloy, solid solution alloy and aged alloy samples have been investigated. Optical microscopy, X-ray diffractometery and scanning electron microscope attached energy spectrometer were used to characterize the microstructure and phase composition for the alloy. Net shaped tau-Mg-32(Al,Zn)(49) phase was obtained at the grain boundary, and needle-like or blocky Al11RE3 phase disperses in grain boundary and alpha-Mg matrix. The tau-Mg-32(Al,Zn)(49) phase disappeared during solution treatment and a new phase of Al(2)CeZn2 formed during subsequent age treatment. The mechanical properties were performed by universal testing machine at room temperature, 150 degrees C and 200 degrees C, separately. The ultimate tensile strength of as-cast alloy is lower compared to an age treatment alloy at 200 degrees C for 12h. The strengths decreased with enhancing test temperature, but elongation has not been effect by age treatment.

Mesoporous acid solid as a carrier for metallocene catalyst in ethylene polymerization and a catalyst in catalytic degradation of polyethylene

The possibility of mesoporous acid solid as a carrier for metallocene catalyst in ethylene polymerization and catalyst for polyethylene (PE) catalytic degradation was investigated. Here, HMCM- 41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves (SAPO1 and SAPO2) were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPO1 mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.

应用基质辅助激光解吸电离飞行时间质谱法测定牛甲状腺球蛋白的分子量

应用基质辅助激光解吸电离飞行时间质谱法测定了牛甲状腺球蛋白的纯度与相对分子量．选择芥子酸为适宜的基质，并对所得的结果进行了讨论．实验结果表明分析方法具有灵敏度高、重现性好、信息直观等特点，明显优于其他传统测定蛋白质的方法.

Synthesis, crystal structure, and density of (W1-xAlx)C

A new solid solution system of Al in WC, with the stoichiometry of (W1-xAlx)C (x = 0.10, 0.25, 0.50, 0.75, 0.86), has been synthesized by a solid-state reaction between W1-xAlx alloys and carbon at around 1673 K in vacuum. Environment scanning electron microscope, energy- dispersive analysis of X-ray, X-ray photoelectron spectroscopy, and inductively coupled plasma analyses are used to certify the formation of the products. The mechanism of the solid-state reaction is also discussed. (W1-xAlx)C is identified to crystallize in the hexagonal space group P6m2 (No. 187) and belongs to the WC structure type. The atoms of W and Al occupy the same lattice site (la site) in the cell of (W1-xAlx)C. The cell parameters for each specimen in the phase of W-AI-C are quite close to that of WC, while their densities are far lower than that of WC.

纳米AgBr/PMMA光致变色杂化材料制备与表征

采用本体聚合法制备了纳米AgBr/PMMA(聚甲基丙烯酸甲酯)光致变色杂化材料.XRD分析表明,纳米AgBr/PMMA杂化材料是无定形的.SEM分析表明,AgBr含量不同,杂化材料的断面形貌明显不同,随AgBr含量的增加,杂化材料由韧性断裂向脆性断裂转变.EDS面分析表明,Ag、Br元素在杂化材料中均匀分布.所制备的纳米AgBr/PMMA杂化材料具有一定的光致变色效应.

Effect of poly(propylene carbonate) on the crystallization and melting behavior of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate)

The crystallization and melting behavior of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV) and a 30/70 (w/w) PHBV/poly(propylene carbonate) (PPC) blend was investigated with differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR). The transesterification reaction between PHBV and PPC was detected in the melt-blending process. The interaction between the two macromolecules was confirmed by means of FTIR analysis. During the crystallization process from the melt, the crystallization temperature of the PHBV/PPC blend decreased about 8 degreesC, the melting temperature was depressed by 4 degreesC, and the degree of crystallinity of PHBV in the blend decreased about 9.4%; this was calculated through a comparison of the DSC heating traces for the blend and pure PHBV. These results indicated that imperfect crystals of formed, crystallization was inhibited, and the crystallization ability of PHBV was weakened in the blend. The equilibrium melting temperatures of PHBV and the 30/70 PHBV/PPC blend isothermally crystallized were 187.1 and 179 degreesC, respectively.

原位聚合制备聚丙烯/蒙脱土纳米复合材料及其结构性能表征

首先制备MMT/MgCl2/TiCl4插层催化剂,并通过原位聚合的方法制得聚丙烯(PP)/蒙脱土(MMT)纳米复合材料。XRD和TEM分析结果表明,蒙脱土在聚丙烯基体中被剥离并成纳米级分散。在低于80℃左右时,PP/MMT纳米复合材料的储能模量明显高于纯聚丙烯的储能模量,PP/MMT复合材料的玻璃化温度比纯PP提高了2℃～5℃。

Sol-gel-derived BPO4/Ba2+ as a new efficient and environmentally-friendly bluish-white luminescent material

In this paper, BPO4 and Ba2+-doped BPO4 powder samples were prepared by the sol-gel process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, quantum yield, kinetic decay, and electron paramagnetic resonance (EPR), respectively. It was found that the undoped BPO4 showed a weak purple blue emission (409 nm, lifetime 6.4 ns) due to the carbon impurities involved in the host lattice. Doping Ba2+ into BPO4 resulted in oxygen-related defects as additional emission centers which enhanced the emission intensity greatly (> 10x) and shifted the emission to a longer-wavelength region (lambda(max) = 434 nm; chromaticity coordinates: x = 0.174, y = 0. 187) with a bluish-white color. The highest emission intensity was obtained ;when doping 6 mol % Ba2+ in BPO4, which has a quantum yield as high as 31%. The luminescent mechanisms of BPO4 and Ba2+-doped BPO4 were discussed in detail according to the existing models for silica-based materials.

Crystallization and characterization of substoichiometric compound (W0.5Al0.5)C-0..5 obtained by solid-state reaction

(W0.5Al0.5)C-0.5 substoichiometric compound is synthesized by a combination of mechanical milling and high-pressure reactive sintering. X-ray diffraction is used to monitor the phase changes and crystallization of (W0.5Al0.5) C-0.5 during the whole reaction process. As a result, (W0.5Al0.5) C-0.5 is identified as the hexagonal WC-type belonging to the P-6m2 space group (No. 187), and the lattice parameters of (W0.5Al0.5)C-0.5 are calculated to be a = 2.907 (1) angstrom, c = 2.838 (1) angstrom, which are very similar to those of WC even if there are approximately 50 pct carbon vacancies in the cell of (W0.5Al0.5)C-0.5 as compared with WC. The substoichiometric (W0.5Al0.5)C-0.5 compound has a Vickers microhardness of 2385 +/- 70 kg mm(-2), which is as high as that of WC, while its density is far lower than that of WC.

Nonisothermal crystallization behavior of poly (L-lactide)-poly(ethylene glycol) dibloick copolymer

The nonisothermal crystallization behavior of poly (L-lactide)-poly(ethylene glycol) ( PLLA-PEG) diblock copolymer was studied by means of real-time WAXD, DSC and POM, and Ozawa equation was used to analyze the kinetics of PLLA-PEG under nonisothermal crystallization conditions. During the crystallization of the high-T-m block (PLLA), the low-T-m block (PEG) acts as a noncrystalline diluent, and the crystallization behavior of PLLA obeys the Ozawa theory. When the PEG block begins to crystallize, the PLLA phase is always partially solidified and the presence of the spherulitic microstructure of PLLA profoundly restricts its crystallization behavior, which results in that the overall crystallization process does not obey the Ozawa equation. Furthermore, the study of the crystalline morphology of PLLA-PEG at different cooling rates indicates that when the cooling rate is from low to high, the crystalline morphology undergoes a transformation from the ring-banded spherulites to the typical Maltese cross spherulites, which experiences the mixed crystalline morphologies of ring-banded and typical Maltese cross spherulites, and the spherulitic size becomes smaller.