Catalysis of the hydrogen oxidation reactions by Sr-doped LaMn1 − yCryO3 ± δ oxides

Sr-doped and Sr-free La_1 − xSr_xMn_1 − yCr_yO_3 ± δ (LSMC, x(Sr) = 0-0.2, y(Cr) = 0.4-0.6) perovskite-type oxides were synthesized and evaluated as single phase anodes for use in intermediate temperature solid oxide fuel cell applications. Their thermo-chemical and chemical stabilities were investigated in hydrogen at high temperatures and correlated with their oxygen non-stoichiometry (3 ± δ), determined by permanganate titration. The catalytic activity towards hydrogen oxidation was examined as a function of oxide sintering time, operating temperature, and the Sr and Cr contents, using a Pt mesh current collector. While all of the perovskite oxides studied here showed some irreversible performance degradation with time under both open circuit and anodically polarized conditions, La_0.9Sr_0.1Mn_0.6Cr_0.4O_3.03 (LSMC9164), sintered at 1200 °C for 10 h, was found to be the most catalytically active and also the most stable.     

I-fuzzy拓扑中的几乎连续与δ-连续

在I-fuzzy拓扑空间框架下引入了I-fuzzy正则开集、I-fuzzyδ-开集等基本概念,进一步,在此基础上又给出了I-fuzzy几乎连续、I-fuzzyδ-连续的概念,且分别研究了I-fuzzy几乎连续、I-fuzzyδ-连续的基本性质.     

氮杂环卡宾催化α,β-不饱和酰氯与亚硝基化合物的[4+2]环化反应

报道氮杂环卡宾催化的α,β-不饱和酰氯与亚硝基化合物的形式[4+2]环化反应合成氮杂-δ-内酯([1,2]嗪-6-酮)化合物.反应机理推测可能是卡宾进攻现场生成的烯基烯酮,得到烯基烯醇负离子,然后与取代的亚硝基苯发生[4+2]环合反应,从而得到的氮杂-δ-内酯产物.     

用双点源δ-P1近似光学模型反演生物组织的光学参量

根据空间分辨漫反射的双点源δ-P₁近似理论模型,采用非线性最小二乘法,从反射率的测量数据中反演得到了生物组织的吸收系数μ_a、有效散射系数μ' _s和二阶参量γ.研究表明,在光源与探测器之间距离大于一个输运平均自由程的情况下,双点源δ-P₁近似能较好地描述光源附近的光辐射分布,而且能够根据参量γ与μ' _s的关系得到组织的各向异性因子g.这些研究对于生物组织的光学性质测量以及漫反射光谱技术的应用具有重要意义. 关键词： 组织光学 P₁近似')" href="#">δ-P₁近似 光学参量 双点源     

β-Zn4Sb3/Zn1-δAlδO复合材料的制备及热电性能研究

采用真空熔融淬火结合放电等离子烧结工艺制备了单相β-Zn₄Sb₃以及β-Zn₄Sb₃/Zn_1-δAl_δO复合热电材料,其中第二相Zn_1-δAl_δO(AZO)的含量分别为0.2 wt%,0.4 wt%和0.7 wt%.对材料的相组成和微结构进行了表征,并在300—673 K的温度 关键词： 4Sb₃')" href="#">β-Zn₄Sb₃ 1-δAl_δO')" href="#">Zn_1-δAl_δO 复合材料 热电性能     

MACROCYCLES. 9. SMECTIC MULTIBLOCK COPOLYESTERS VIA MACROCYCLIC POLYMERIZATION OF δ-VALEROLACTONE AND ε-CAPROLACTONE

Using 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) as cyclic initiator 1:1 copolymerizations of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VC) were conducted in bulk at 80°C. A nearly equimolar incorporation and a random sequence were found by NMR spectroscopy and crystallization below 20°C was detected by DSC measurements. In a second series of experiments, the in situ formed macrocyclic copolyesters were reacted with an excess of sebacoyl chloride and after addition of silylated 4,4′,-dihydroxybiphenyl copolycondensations were performed in bulk at 230°C. These copolycondensations proceeded satisfactorily without significant transesterification and despite a biphasic character of the melt. This biphasic character resulted from the formation of a smectic LC-phase by the 4,4′-dioxybiphenyl sebacate blocks. For comparison a homopolyester was prepared from sebacoyl chloride and silylated 4,4′-dihydroxybiphenyl. The thermal properties of this homopolyester and of the LC-blocks in the copolyester were nearly identical indicating the absence of transesterification during the synthesis at 230°C. However, the properties of the LC-phase above 200–210°C did not completely agree with the data reported for the homopolyester in the literature (which are themselves inconsistent).     

Capillary zone electrophoresis and capillary electrophoresis-mass spectrometry for analyzing qualitative and quantitative variations in therapeutic albumin

The present study describes a reproducible and quantitative capillary zone electrophoresis (CZE) method, which leads to the separation of nine forms (native, oxidized and glycated) of human serum albumin (HSA). In an attempt to identify the different species separated by this CZE method, the capillary electrophoresis was coupled to mass spectrometry using a sheath liquid interface, an optimized capillary coating and a suitable CE running buffer. CE-MS analyses confirmed the heterogeneity of albumin preparation and revealed new truncated and modified forms such as Advanced Glycation End products (AGEs). Assignment of the CZE peaks was carried out using specific antibodies, carboxypeptidase A or sample reduction before or during the CE separation. Thus, five HSA forms were unambiguously identified. Using this CZE method several albumin batches produced by slightly different fractionation ways could be discriminated. Furthermore, analyses of HSA preparations marketed by five pharmaceutical industries revealed that two therapeutic albumins, including that marketed by LFB, contained the highest proportion of native form and lower levels of oxidized forms.     

Synthesis of (+)-(3R,5R)-3-Hydroxy-5-decanolide and Massoialactone,and Formal Synthesis of Verbalactone

Total synthesis of (3R, 5R)-(+)-3-hydroxy-5-decanolide (1) and massoialactone (2), and formal synthesis of verbalactone (3), have been reported.     

Tetra-n-butylammonium Fluoride–Catalyzed Eschenmoser–Claisen [3,3]-Sigmatropic Rearrangement

Condensation of dibenzofuran and dibenzothiophene carboxaldehydes with various aryl acetic acids followed by esterification of the acid intermediate afforded the 2,3-diaryl acrylates in good overall yields. Reduction of the esters with diisobutylaluminium hydride afforded the allylic alcohols, which underwent a smooth Eschenmoser–Claisen [3,3]-sigmatropic rearrangement on exposure to N,N-dimethylacetamide dimethylacetal in the presence of tetra n-butylammonium fluoride as catalyst to give 3,4-diaryl γ,δ-unstaturated amides in excellent yields.     

Molecular features related to the binding mode of PPARδ agonists from QSAR and docking analyses

Diabetes affects approximately 4% of world’s population and metabolic syndrome has been directly related to obesity. There is a class of nuclear receptors, peroxisome proliferator-activated receptors (PPARs), which controls the metabolism of carbohydrates and lipids. It has been considered an attractive target to treat diabetes and metabolic syndrome. Accordingly, the primary objective of this study was to employ molecular modelling techniques to understand the factors involved in PPARδ activation. The QSAR models obtained showed good internal and external consistency and presented good validation coefficients (QSAR: q² = 0.83, r² = 0.87; HQSAR: q² = 0.73, r² = 0.90; CoMFA: q² = 0.88, r² = 0.94). The selected properties and the contour maps described the possible interactions between the PPARδ receptor and its agonists. From these findings, it is possible to propose molecular modifications to design new compounds with improved biological properties.