采用静电纺丝/非溶剂致相分离制备聚丙烯腈多孔超细纤维的研究

以聚丙烯腈/二甲基亚砜/N,N'-二甲基甲酰胺三元体系为纺丝液、3℃水浴为接收介质,通过静电纺丝制备了具有纳米孔结构的静电纺聚丙烯腈多孔超细纤维.探讨了溶剂比例、接收介质、聚丙烯腈浓度、纺丝电压及接收距离等因素对纤维直径和表面孔隙率的影响.结果表明最佳制备条件为混合溶剂质量比1∶1、纺丝电压16 kV、聚丙烯腈浓度15 wt%、接收距离5 cm、纺丝速率0.7 mL/h、环境温度25℃、相对湿度40%～70%.在此条件下得到的聚丙烯腈多孔超细纤维直径在420～490 nm,平均直径468 nm,表面孔隙率3.4%,纤维内部形成大量孔径为8～30 nm的孔结构,且孔径分布均匀,孔形状相对一致.N2吸附脱附测试表明,聚丙烯腈多孔纤维的BET比表面积达43.86 m2/g,是相同直径无孔聚丙烯腈纤维比表面积理论值的6倍.通过研究聚丙烯腈/(二甲基亚砜+N,N'-二甲基甲酰胺)/水的三元相图,提出非溶剂致相分离是主要成孔机理.     

Catalytic properties of Pd supported on hexaaluminate coated alumina in low temperature combustion of coal mine ventilation air methane

Palladium supported on γ-Al₂O₃ has been demonstrated as most active catalyst for catalytic combustion of methane. However, the sintering of support and PdO seriously affects its activity. We prepared a composite Pd/hexaaluminate/Al₂O₃ catalyst and compared its catalytic activity as well as sintering behavior with Pd/Al₂O₃. This composite catalyst exhibits higher activity and better resistance to sintering. The effect of water vapor presented in feed has also been investigated.     

基于端元可变的喀斯特地形复杂区石漠化信息提取

喀斯特山区因地形复杂、地表破碎等特点使得遥感影像中阴影、混合像元及光谱变异现象普遍存在,传统基于多光谱遥感的像元二分法（DPM）在光谱变异和阴影显著的区域难以准确的对喀斯特石漠化（KRD）信息进行提取。采用高光谱遥感的混合像元分解技术可将复杂的混合像元分解为纯净的地物光谱与各地物光谱对应的混合比例,为复杂山区获取更高精度的石漠化信息提供可能。然而,由于光照、环境及大气等诸多因素的变化会引起端元发生不同程度变异,导致在混合像元分解过程中出现显著的误差,其次要从地形复杂、地表异质性强的山区影像上直接获取地物纯净光谱建立用于应对光谱变异的光谱库极其困难。因此,如何在这种情况下应对光谱变异和地形效应,获取有效、准确的对石漠化信息进行提取是当前研究的重点。针对以上问题,采用通过模拟由光照条件造成的地物反射率变化,并考虑每个波长间隔光谱变异情况的广义线性混合模型（GLMM）,以减轻喀斯特地区石漠化信息提取过程中光谱变异与地形效应的影响。首先,从GF-5高光谱影像中提取喀斯特地区主要地物（植被、裸岩、裸土）的典型代表性光谱,然后基于提取的地物光谱模拟不同光照下每个像元光谱的变异情况,选择最适合的光谱组合对像元进行分解,得到最优的解混效果。为了验证方法的可靠性,利用高分辨率影像目视解译的结果作为参考对方法预测结果进行验证,同时选择未考虑端元变异的全限制最小二乘法（FCLSU）和DPM进行对比。结果表明,在地形高度复杂的喀斯特山区,考虑阴影、混合像元及光谱变异是必要的,GLMM在石漠化信息提取中总精度达到了84.89%,明显高于其他两种方法的59.68%和67.34%。通过对光照区和阴影区分别进行精度检验,发现GLMM在光照区与阴影区有着相似的精度表现,而另外两者则差异较大,阴影区明显低于光照区。这反映GLMM能较为有效地减轻地形效应的影响,对喀斯特石漠化信息提取的精度有一定提升。     

鱼藤酮肟羧酸酯的合成和生物活性

以鱼藤酮为原料,经肟化、酯化反应合成了9种鱼藤酮肟羧酸酯新化合物,化合物经1H NMR、红外、元素分析等确证结构.生物活性试验结果表明:3a,3b和3c对家蝇(0.30 mg/mL)死亡率分别为80.0%,90.0%和95.0%,对甜菜夜蛾(0.10 mg/mL)的致死率分别为57.1%,60.0%和73.3%;3b对粘虫(1.00mg/mL)的致死率为86.4%,对叶蝉(0.50 mg/mL)的致死率为71.8%;3c对粘虫(1.00mg/mL)的致死率为100%;3a对叶蝉(0.50 mg/mL)的致死率为54.2%.     

基于光谱成像技术的乳块消素片活性成分空间分布及均匀性研究

建立乳块消素片活性成分橙皮苷的空间分布和总体成分均匀性的质量控制方法,为片剂生物利用度与成分分布相关性研究提供基础.采用近/中红外漫反射光谱成像技术,运用基础相关系数分析方法.鉴别素片表面橙皮苷成分的分布区;通过直方图统计分析,探讨素片成分的分布均匀性.橙皮苷近红外光谱与素片表面光谱的最高相关系数为0.75;而中红外光...     

Ruthenium complexes of thiaporphyrin and dithiaporphyrin

Successful synthesis and characterization of the six-coordinated complex [Ru(STTP)(CO)Cl] (1; STTP = 5,10,15,20-tetratolyl-21-thiaporphyrinato) allowed the development of the coordination chemistry of ruthenium-thiaporphyrin through dechlorination and metathesis reactions. Accordingly, [Ru(II)(STTP)(CO)X] (X = NO(3)(-) (2), NO(2)(-) (3), and N(3)(-) (4)) was synthesized and analyzed by single-crystal X-ray structural determination and NMR, UV-vis, and FT-IR spectroscopic methods. An independent reaction of STPPH and [Ru(COD)Cl(2)] led to [Ru(III)(STTP)Cl(2)] (5), which possessed a higher-valent Ru(III) center and exhibited good stability in the solution state. This stability allowed reversible redox processes in a cyclic voltammetric study. Reactions of [Ru(S(2)TTP)Cl(2)] (S(2)TTP = 5,10,15,20-tetratolyl-21,23-dithiaporphyrinato) with AgNO(3) and NaSePh, also via the metathesis strategy, resulted in novel dithiaporphyrin complexes [Ru(II)(S(2)TTP)(NO(3))(2)] (6) and [Ru(0)(S(2)TTP)(PhSeCH(2)SePh)(2)] (7), respectively. The structures of 6 and 7 were corroborated by X-ray crystallographic analyses. Complex 7 is an unprecedented ruthenium(0)-dithiaporphyrin with two bis(phenylseleno)methanes as axial ligands. A comparison of the analyses of the crude products from reactions of NaSePh and CH(2)Cl(2) with or without [Ru(S(2)TTP)Cl(2)], further supported by UV-vis spectral changes under stoichiometric reactions between [Ru(S(2)TTP)Cl(2)] and NaSePh, suggested a reaction sequence in the order of (1) formation of a putative [Ru(II)(S(2)TTP)(SePh)(2)] intermediate, followed by (2) the concerted formation of PhSe-CH(2)Cl and simultaneously a reduction of Ru(II) to Ru(0) and finally (3) nucleophilic substitution of PhSeCH(2)Cl by excess PhSe(-), resulting in PhSeCH(2)SePh, which readily coordinated to the Ru(0) and completed the formation of bis(phenylseleno)methane complex 7.     

Ordered structures of defect clusters in gadolinium-doped ceria

The nano-domain, with short-range ordered structure, has been widely observed in rare-earth-doped ceria. Atomistic simulation has been employed to investigate the ordering structure of the nano-domain, as a result of aggregation and segregation of dopant cations and the associated oxygen vacancies in gadolinium-doped ceria. It is found that the binding energy of defect cluster increases as a function of cluster size, which provides the intrinsic driving force for the defect cluster growth. However, the ordered structures of the defect clusters are different from the chain model as previously reported. Adjacent oxygen vacancies prefer to locate along <110>/2 lattice vector, which results in a unique stable structure (isosceles triangle) formation. Such isosceles triangle structure can act as the smallest unit of cluster growth to form a symmetric dumbbell structure. This unique dumbbell structure is hence considered as a building block for the development of larger defect clusters, leading to nano-domain formation in rare-earth-doped ceria.     

Microstructural and metal-support interactions of the Pt-CeO2/C catalysts for direct methanol fuel cell application

To understand the ceria promotion effect of Pt-CeO(2)/C catalysts on methanol oxidation, microstructural and metal-oxide interactions of Pt-CeO(2)/C catalysts with an atomic ratio of Pt/Ce between 0.14 and 1.4 were systematically examined using high-resolution transmission electron microscopy and electron energy loss spectroscopy (EELS). With an increasing Pt content in the catalysts, Pt particles gradually invaded into the ceria supports and decoration on Pt particles was observed. Simultaneously, the morphology of the supports was dramatically modified with nanocrystalline and amorphous ceria formed between and/or around the Pt particles. It reveals that the Pt-ceria interaction could take place in the catalysts and the influence of the interaction was enhanced with an increasing Pt/Ce ratio. The EELS study demonstrated that the strong Pt-ceria interaction was related to the redox reaction between Pt and ceria. Experimental results also suggested that the strong interaction between Pt and ceria could contribute to the promotion effect of ceria on the oxidation of methanol.     

NMR spectral assignments of two sterols from a soft coral Sinularia brassica

Two new steroids, named 4α,22-dimethyl-Cholest-22-en-3β-ol (1) and 4α-methyl-Cholest-7,22-dien-3β-ol (2), along with two known steroids, were isolated from the soft coral Sinularia brassica. The structures of the new compounds were determined on the basis of extensive spectroscopic data (MS, (1)H and (13)C NMR, (1)H-(1)H COSY, (13)C-(1)H COSY, HMBC and NOESY) analysis.     

Design and synthesis of iridium bis(carbene) complexes for efficient blue electrophosphorescence

Five iridium bis(carbene) complexes, [Ir(pmi)(2)(pypz)] (1), [Ir(mpmi)(2)(pypz)] (2), [Ir(fpmi)(2)(pypz)] (3), [Ir(fpmi)(2)(pyim)] (4), and [Ir(fpmi)(2)(tfpypz)] (5) (pmi=1-phenyl-3-methylimdazolin-2-ylidene-C,C(2'); fpmi=1-(4-fluorophenyl)-3-methylimdazolin-2-ylidene-C,C(2'); mpmi=1-(4-methyl-phenyl)-3-methylimdazolin-2-ylidene-C,C(2'); pypz=2-(1H-pyrazol-5-yl)pyridinato; pyim=2-(1H-imidazol-2-yl)pyridinato; and tfpypz=2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridinato), were synthesized and their structures were characterized by NMR spectroscopy, mass spectroscopy and X-ray diffraction. These complexes showed phosphorescent emission with the emission maxima between 453 and 490 nm. Various spectrophotometric measurements, cyclic voltammetric studies, and density functional theory (DFT) calculations show that, unlike most of the phosphorescent cyclometalated iridium complexes, the lowest unoccupied molecular orbital (LUMO) energy and the emissive state of these iridium complexes are mainly controlled by the N,N'-heteroaromatic (N^N) ligand. Despite the fact that the LUMO levels of these complexes are mainly on the N^N ligands, the efficiencies of the electroluminescent (EL) devices are very high. For example, the EL devices using [Ir(mpmi)(2)(pypz)], [Ir(fpmi)(2)(pypz)], and [Ir(fpmi)(2)(tfpypz)] as the dopant emitters exhibited light- to deep-blue electrophosphorescence with external quantum efficiencies of 15.2, 14.1, and 7.6% and Commission Internationale d'énclairage (x,y) coordinates (CIE(x,y)) of (0.14, 0.27), (0.14, 0.18) and (0.14, 0.10), respectively.