Hydrothermal synthesis and thermal properties of a novel cubic ZrW1.80V0.20O7.90 solid solution

Tetragonal ZrW_1.80V_0.20O_6.90(OH)_2.00(H₂O)_2.00 hydrate was prepared using an acidic steam hydrothermal (ASH) method. Thermal dehydration followed by phase transformation of this precursor leads to successful synthesis of a novel W-site low-valent substituted cubic ZrW_1.80V_0.20O_7.90 solid solution, the mechanism of this process is studied in detail revealing the hydrate and a metastable orthorhombic phase of V′_Wsubstitution solid solution as important intermediate product. This material is found to possess thermal contraction and order-disorder phase transformation properties similar to that of the cubic ZrW₂O₈.     

Synthesis and characterization of self-assembled c-axis oriented Bi2Sr3Co2O(y) thin films by the sol-gel method

Bi(2)Sr(3)Co(2)O(y) thin films are prepared on SrTiO(3) (100), (110) and (111) single crystal substrates using the sol-gel method. All the thin films are c-axis oriented regardless of the orientation of the substrate suggesting self-assembled c-axis orientation, and X-ray photoelectron spectroscopy results give evidence of coexistence of Co(3+) and Co(2+) ions in the derived films. Transmission electronic microscopy observations reveal that all samples are c-axis oriented with no obvious differences for different samples, and the c-axis lattice constant is determined as ~15 ? suggesting the misfit structure. A phenomenological thermodynamic phase diagram for self-assembled c-axis orientation is established for misfit cobaltate-based films using chemical solution deposition. All samples behave like semiconductors due to the coexistence of Co(3+)/Co(2+) ions, and the resistivity at 350 K is ~47, 39 and 17 mΩ cm for the thin films on SrTiO(3) (100), (110) and (111), respectively, whereas the Seebeck coefficient at 300 K is 97, 89 and 77 μV K(-1). The successful attainment of Bi(2)Sr(3)Co(2)O(y) thin films with self-assembled c-axis orientation will provide an effective prototype for investigation of growth mechanisms in complex oxide thin films with a misfit structure.     

Promoted dehydrogenation in ammine lithium borohydride supported by carbon nanotubes

In this paper, ammine lithium borohydride (LiBH(4)·NH(3)) was successfully impregnated into multi-walled carbon nanotubes (CNTs) through a melting technique. X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller, and density measurements were employed to confirm the formation of the nanostructured LiBH(4)·NH(3)/CNTs composites. As a consequence, it was found that the dehydrogenation of the loaded LiBH(4)·NH(3) was remarkably enhanced, showing an onset dehydrogenation at temperatures below 100 °C, together with a prominent desorption of pure hydrogen at around 280 °C, with a capacity as high as 6.7 wt.%, while only a trace of H(2) liberation was present for the pristine LiBH(4)·NH(3) in the same temperature range. Structural examination indicated that the significant modification of the thermal decomposition route of LiBH(4)·NH(3) achieved in the present study is due to the CNT-assisted formation of B-N-based hydride composite, starting at a temperature below 100 °C. It is demonstrated that the formation of this B-N-based hydride covalently stabilized the [NH] groups that were weakly coordinated on Li cations in the pristine LiBH(4)·NH(3)via strong B-N bonds, and furthermore, accounted for the substantial hydrogen desorption at higher temperatures.     

Phase Behavior and Rheological Properties of Concentrated Lecithin Aqueous Solutions with Additives

The phase behavior and rheological properties of the concentrated lecithin aqueous solutions were investigated at 37°C. When adding Isopropyl myristate (IPM) to lecithin solutions, besides an anisotropic liquid crystal (LC) phase, an isotropic liquid (L₂) region and an isotropic viscous (I) phase are found. By continuously adding Brij 97, the LC region shifts towards higher water content and the L₂ region is extended to the area of lower IPM concentration, meanwhile the I phase disappears. By analyzing the shear rate (η_γ=0.1) and yield stress (σ₀), adding IPM to lecithin solutions increases the values of η_γ=0.1 and σ₀, and after further adding Brij 97, the η_γ=0.1 and σ₀ decrease dramatically. Notably, different from the lecithin/DDAB/water system studied by Youssry and Montalvo, in lecithin/Brij 97/IPM/H₂O system, at the relatively higher water content area of the LC phase, the water content has little effect on the critical stress. It is also found that the change of dynamic storage modulus (G′) is similar with that of η_γ=0.1 and σ₀ parameters when adding IPM and Brij 97. Maxwell model fitting results show that in the LC phase, the relaxation of the water molecule is prolonged by adding IPM and Brij 97 to lecithin solutions.     

Pretreatment of Corn Stover Silage with Fe(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> for Fermentable Sugar Production

Corn stover silage is an attractive raw material for the production of biofuels and chemicals due to its high content of carbohydrates and easy degradability. The effects of Fe(NO₃)₃ pretreatment conditions on sugar yields were investigated for corn stover silage. In addition, a combined severity factor was used to evaluate the effect of pretreatment conditions on the concentration of total sugars and inhibitors. Optimum pretreatment condition was obtained at 150 °C for 10 min with 0.05 M Fe(NO₃)₃, at which the yields of soluble xylose and glucose in liquid achieved 91.80% of initial xylose, 96.74% of initial arabinose and 19.09% of initial glucose, respectively, meanwhile, 91.84% of initial xylose, 98.24% of initial arabinose, and 19.91% of initial glucose were removed. In addition, a severity analysis showed that the maximum sugar concentration of 33.48 g/l was achieved at combined severity parameter value of 0.62, while the inhibitor concentration was only 0.03 g/l. Fe(NO₃)₃ is an effective catalyst to enhance hemicellulose hydrolysis in corn stover silage, the yields of monomeric xylose in the liquid fraction reached as high as 91.06% of initial xylose and 96.22% of initial arabinose, respectively.     

PMC敏化SnO2纳米结构多孔膜电极的光电化学特性

研究了五甲川菁(PMC)敏化SnO2纳米结构电极的光电化学行为.结合循环伏安曲线及五甲川菁的光吸收阈值,初步确定了五甲川菁染料电子基态和激发态能级.结果表明,五甲川菁染料电子激发态能级能与SnO2纳米粒子导带边位置相匹配,因而使用该染料敏化可以显著地提高SnO2纳米结构电极的光电流,使SnO2纳米结构电极吸收波长红移至可见光区和近红外区,光电转换效率(IPCE)得到明显改善,其值最高可达45.7%.     

Synthesis and biodistribution of the 99m TcN-DMSA complex as a potential bone imaging agent

In this study, the preparation of the 99m TcN complex of DMSA (dimercaptosuccinicacid) was carried out as a freeze-dried formulation, through a simple procedureinvolving the initial of 99m TcO 4 – with succinic dihydrazide in thepresence of stannous chloride as reducing agent, followed by the additionof the ligand DMSA to afford the final product. The radiochemical purity ofthe 99m TcN-DMSA complex was over 90% determined by thin layer chromatography.It was stable over 8 hours at room temperature. Its partition coefficientindicated that it was a good hydrophilic complex. Biodistribution in miceshowed that the 99m TcN-DMSA complex was accumulated in bone with high uptakeand good retention, suggesting it would be potentially useful as a bone imagingagent containing the [ 99m TcN] 2+ core. The biodistribution comparison inmice of the 99m TcN-DMSA complex and the 99m Tc-DMSA complex indicate thatthe presence of the 99m Tc nitrido group significantly alters the biologicalproperties of the 99m Tc complex.     

Yttria promoted metallic nickel catalysts for the partial oxidation of methane to synthesis gas

A metallic Ni catalyst was prepared with nickel sponge, followed by acid treatment. It was further promoted with yttria by an impregnation method. The catalysts were characterized by SEM, BET, XRD, TPR, XPS, etc., and studied in the partial oxidation of methane to syngas. The characterization results showed that the yttria promoted metallic Ni catalysts had high specific surface area and more NiO. The reaction results showed that the yttria promoter increased the CH4 conversion and the selectivity for H2 and CO.     

Cl＋C_2H_6→HCl＋C_2H_5反应的准经典轨线研究

用三原子模型的准经典轨线方法研究了Cl与C2H6（v=0,j）的反应．计算结果表明，反应产物HCl的角度分布基本上为各向同性，其振转分布处于基态，与实验结果相一致,对反应轨线的研究表明，该反应为一直接反应．而且反应碰撞在低及高的碰撞参数下的机理不一样．在低碰撞参数下反应碰撞是直接完成的，产物HCl以向后散射为主，转动基本上是冷的，但比高碰撞参数下的热.在高的碰撞参数下则生成短寿命的碰撞复合物，产物HCl以向前散射为主，转动较冷．