Spatial distribution of reaction products in direct ethanol fuel cell

The electro-catalytic oxidation of ethanol in a direct-type polymer electrolyte membrane fuel cell is known to be more complex than that of methanol. We used both solution and solid-state nuclear magnetic resonance (NMR) methods for the first time to successfully identify and quantify the reaction intermediates and the fuel itself which were distributed differently over fuel pathways and the polymer membrane (PEM) in the direct ethanol fuel cell (DEFC). The diverse chemical species present in the exhaust were identified by high-resolution solution NMR, while the nature and amounts of the species in the PEM of the DEFC were analyzed by solid-state NMR. The relative amount of reaction intermediates of ethanol detected in the PEM was an order of magnitude higher than that observed in the exhaust, which might be of critical importance in understanding and developing DEFC systems.     

堆焊熔敷层表面纳米晶层摩擦磨损性能研究

用预压力滚压技术在堆焊修复层表面制备纳米晶层.利用TEM、SEM分析技术研究表面纳米晶层微观结构,利用CETR-3型多功能摩擦磨损试验机考察在干摩擦条件下堆焊层表面纳米晶层的摩擦磨损性能.结果表明堆焊修复层表面经表面纳米化处理后,表面形成厚度约为10μm(晶粒尺寸小于100 nm)的纳米晶层,最表面层平均晶粒尺寸约为10 nm.纳米压痕试验表明纳米晶层的硬度提高,最表面纳米晶层的硬度约为原始堆焊层硬度的3倍.与原始堆焊试样相比,表面纳米化试样的摩擦系数降低了10%,磨损体积降低了25%~30%左右.表面纳米化样品的磨损机制由原始堆焊层的磨粒磨损和黏着磨损转变为磨粒磨损,分析表明晶粒细化导致的高硬度、低塑性是摩擦磨损性能改善和磨损机制改变的主要原因.     

27Al Magic Angle Spinning Nuclear Magnetic Resonance Study of Al1−x Cr x K(SO4)2·12H2O (x = 0, 0.07, and 0.2)

The physical properties of Al_1?x Cr _x K(SO₄)₂·12H₂O (x = 0, 0.07, and 0.2) were studied as a function of temperature using magic angle spinning nuclear magnetic resonance for ²⁷Al. On the basis of the physical properties of pure AlK(SO₄)₂·12H₂O, the effects of partially replacing Al³⁺ with Cr³⁺ ions were examined. Molecular motion changed with the concentration of Cr³⁺ ions. The relaxation process near 320 K was found to undergo molecular motion as described by the Bloembergen–Purcell–Pound theory. The activation energies, phase transition temperatures, and spin–lattice relaxation times in the rotating frame T _1ρ changed with the concentration of paramagnetic ions.     

Barium Sodium Niobate Powders and Thin Films: Preparation and Ferroelectric Behavior

Powders and thin films of barium sodium niobate, Ba₄Na₂Nb₁₀O₃₀, of filled tungsten bronze type ferroelectric were processed by a sol-gel route using barium metal, niobium ethoxide and sodium methoxide as precursors. Polycrystalline powder resulted after heat treating the gel powder at or above 650°C. Thin films of Ba₄Na₂Nb₁₀O₃₀ showed no preferred orientation on Si(100), Pt/Si(100) and sapphire substrates. Hysteresis measurements at 1 kHz for the thin films annealed at 750°C, obtained using a prehydrolyzed precursor solution, and gave remanent polarization of 17.34 µC/cm² and coercive field of 62.5 kV/cm. Microstructural investigation of surface morphology of these films revealed grains about 0.3 µm in size. Prehydrolysis of the precursor solution was found to be necessary to achieve dense films with ferroelectric properties.     

Serum exosomal microRNAs as novel biomarkers for hepatocellular carcinoma

Recent studies have shown that circulating microRNAs are a potential biomarker in various types of malignancies. The aim of this study was to investigate the feasibility of using serum exosomal microRNAs as novel serological biomarkers for hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB). We measured the serum exosomal microRNAs and serum circulating microRNAs in patients with CHB (n=20), liver cirrhosis (LC) (n=20) and HCC (n=20). Serum exosomal microRNA was extracted from 500 μl of serum using an Exosome RNA Isolation kit. The expression levels of microRNAs were quantified by real-time PCR. The expression levels of selected microRNAs were normalized to Caenorhabditis elegans microRNA (Cel-miR-39). The serum levels of exosomal miR-18a, miR-221, miR-222 and miR-224 were significantly higher in patients with HCC than those with CHB or LC (P<0.05). Further, the serum levels of exosomal miR-101, miR-106b, miR-122 and miR-195 were lower in patients with HCC than in patients with CHB (P=0.014, P<0.001, P<0.001 and P<0.001, respectively). There was no significant difference in the levels of miR-21 and miR-93 among the three groups. Additionally, the serum levels of circulating microRNAs showed a smaller difference between HCC and either CHB or LC. This study suggests that serum exosomal microRNAs may be used as novel serological biomarkers for HCC.     

治疗胆石症蒙药苏斯-12中多种元素的ICP-AES法测定及分析

通过分析治疗胆囊炎、胆石症的蒙药苏斯—12中微量元素含量,探讨蒙药苏斯—12的药效与微量元素含量的关系。应用高压密封微波消解、电感耦合等离子体原子发射光谱法(ICP-AES)对蒙药苏斯—12进行微量元素含量分析。在蒙药的配制及整体研究工作中发现它们含有多种氨基酸和丰富的微量元素,实验结果表明：苏斯—12中含有丰富的微量元素,尤其Ca,Al,Mg,Fe,Sr,Mn,Zn,Cu等元素的含量比较高,而Pb,Cd,As等元素含量相对低,都低于国家限定值。加标回收率在94.63%～106.40% 之间,相对标准偏差RSD≤3.35 %,检出限在≤0.009 μg·L-1。蒙药苏斯—12有效控制和治疗胆囊炎、胆石症,总有效率达91.2%和100%,蒙药苏斯—12中的微量元素与药效之间有密切的关系。