Selective Synthesis of Z‐Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light‐Promoted Photocatalytic E to Z Isomerization

A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z‐cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z‐magnolol and honokiol derivatives possessing potential biological activity.     

纳米金对荧光素的荧光增效作用

纳米金对荧光素的荧光效率具有增强作用,其增强效果取决于纳米金的尺寸大小和浓度。粒径分别为5、15、25 nm的纳米金与不同浓度的荧光素溶液作用后可以增强荧光强度3~10倍,同时讨论了溶液环境和pH值对荧光增强的影响。采用本实验提出的方法可以在生化检测方面提高荧光检测方法的灵敏度。     

Vibrational analysis for multi-channel decomposition reactions of o-pyridyl radical based on DFT methods

The decomposition reaction pathways of o-pyridyl were investigated extensively at the B3LYP/6-311G** level. With the relative energies after zero-point energy correction, the potential energy surface was drawn out. The vibrational frequencies for all species were predicted and the reaction mechanism was elucidated utilizing vibrational frequencies and vibrational mode analysis. The primary products of o-pyridyl decomposition reactions are acetylene and cyanoacetylene.     

A tumor mRNA-mediated bi-photosensitizer molecular beacon as an efficient imaging and photosensitizing agent

A bi-photosensitizer molecular beacon (bi-PS MB) is assembled by coupling two PS molecules, respectively, onto the opposite ends of a single MB. The MB can be triggered by a tumor marker-survivin mRNA. Fluorescence and cytotoxic (1)O(2) generation occur effectively in breast cancer cells, but not in normal cells. Compared with a single-PS MB, a bi-PS MB exhibits much-enhanced properties in the signal-to-background ratio and (1)O(2) generation simultaneously.     

5kW/4.5K氦制冷系统外纯化器吸附筒设计

纯化器设计的关键是求解吸附剂对吸工质的吸附容量。文中根据朗格缪尔方程式,对活性炭在78K温度下对氮、氧等杂质的吸附容量进行了计算与分析,研究杂质气体中氮、氢比例对吸附容量的影响。在计算结果基础上,对吸附筒进行机械结构设计和应力分析。     

A new nanobiosensor for glucose with high sensitivity and selectivity in serum based on fluorescence resonance Energy transfer (FRET) between CdTe quantum dots and Au nanoparticles

A novel assembled nanobiosensor QDs-ConA-beta-CDs-AuNPs was designed for the direct determination of glucose in serum with high sensitivity and selectivity. The sensing approach is based on fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) as an energy donor and gold nanoparticles (AuNPs) as an energy acceptor. The specific combination of concanavalin A (ConA)-conjugated QDs and thiolated beta-cyclodextrins (beta-SH-CDs)-modified AuNPs assembles a hyperefficient FRET nanobiosensor. In the presence of glucose, the AuNPs-beta-CDs segment of the nanobiosensor is displaced by glucose which competes with beta-CDs on the binding sites of ConA, resulting in the fluorescence recovery of the quenched QDs. Experimental results show that the increase in fluorescence intensity is proportional to the concentration of glucose within the range of 0.10-50 muM under the optimized experimental conditions. In addition, the nanobiosensor has high sensitivity with a detection limit as low as 50 nM, and has excellent selectivity for glucose over other sugars and most biological species present in serum. The nanobiosensor was applied directly to determine glucose in normal adult human serum, and the recovery and precision of the method were satisfactory. The unique combination of high sensitivity and good selectivity of this biosensor indicates its potential for the clinical determination of glucose directly and simply in serum, and provides the possibility to detect low levels of glucose in single cells or bacterial cultures. Moreover, the designed nanobiosensor achieves direct detection in biological samples, suggesting the use of nanobiotechnology-based assembled sensors for direct analytical applications in vivo or in vitro.     

A novel assembly of Au NPs-beta-CDs-FL for the fluorescent probing of cholesterol and its application in blood serum

A novel assembly of Au NPs-beta-CDs-FL for the fluorescent probing of cholesterol (Cho) is provided. Gold nanoparticles (Au NPs) possessing a high extinction coefficient function can be used as excellent fluorescent quenchers in Au NP-fluorophore composites. Inclusion of fluorescein (FL) into beta-cyclodextrin (beta-CD) makes fluorescence resonance energy transfer (FRET) occur through the donor and quencher nearby. FRET switches off because of the cholesterol-induced release of FL from beta-CD cavity, which results in the fluorescence recovery of the quenched dye. Spectral analysis supported the idea that the signal enhancement was attributed to the formation of an inclusion complex of the cholesterol moiety in beta-CD, resulting in separation of FL from the Au NPs. This phenomenon is explained by the guest-induced location change of the FL from inside to outside the cavity, suggesting that the assembly of Au NPs-beta-CDs-FL is effective as a fluorescent probe for cholesterol recognition. The fluorescence increase is proportional to the concentration of cholesterol in the range of approx. 30 nM to 15 muM. A concentration of cholesterol as low as 9 nM would be readily detected. The precision of the method applied to the determination of quantities of cholesterol present in human blood serum were satisfactory.     

二氧化碳膨胀乙醇体系中碳基金属复合物的合成及其催化和电化学性能(英文)

与块体材料相比,功能复合材料表现了更加优异的性能,而且比其中任何单一组分的性能都好,因此在催化、锂离子电池等领域得以广泛研究.通常情况下,在复合材料的制备中金属或金属氧化物粒子要求能够以足够小的粒径在基底上均匀分散,并实现活性组分负载量的可控.据报道,很多方法可以将金属(或氧化物)活性组分引入到载体之中,比如水热/溶剂热、水解、热分解、化学气相沉积等,但这些方法均存在如下缺点.第一,为了获得满意的负载量和可控包覆,碳基底需要预氧化处理使其表面含有丰富的含氧官能团.例如,由于碳纳米管自身的相容性和加工性较差,需要硝酸预氧化处理;石墨烯也需要预处理为石墨烯氧化物然后再进行第二组分的负载.但是,剧烈的氧化处理条件不可避免地造成对碳sp~2结构和电子特性的破坏,并且增加了繁杂的后续处理过程.第二,金属组分前驱体在基底上负载不完全,易形成自由粒子聚集在溶液中,从而降低活性组分的有效利用.第三,传统方法中由于使用水、乙醇等表面张力大的极性溶剂,导致粒子结晶再生长,形成的颗粒尺寸大,对催化剂会降低活性表面积及催化效率;对于电池材料会增加电极/电解液的接触面积,增加锂离子的扩散距离及电池充电过程的内部应力.而且,有机溶剂由于粘度大,不利于金属纳米粒子在基底上的均匀分散及合成过程的绿色化.因此,我们利用资源丰富,廉价的二氧化碳作为绿色溶剂,研究了二氧化碳膨胀的乙醇体系中金属(氧化物)纳米粒子在碳基底上均匀负载的方法.由于超临界二氧化碳具有独特的低粘度、"零"表面张力、高扩散能力、以及物性参数随温度和压力可调等特点,可以使金属(氧化物)前驱体不受液体毛细作用的限制在孔道中快速、均一地分散,保证孔结构稳定,对多孔复合材料的加工和制备表现了巨大的优势.同时,超临界二氧化碳的抗溶剂能力也能够有效降低乙醇和水引起的溶剂效应,从而降低纳米粒子之间的聚集.此外,通过改变前驱体的浓度可以精确调控表面组分的负载量.更重要的是,碳基底可以直接利用制备碳基复合材料,无需任何预处理及表面活性剂参与,避免了前处理对基底的形貌和电子特性的破坏.本综述首先介绍了超临界二氧化碳膨胀乙醇体系的属性,讨论了碳基复合材料在该体系中的形成机理.然后分别介绍了零维碳球、一维碳纳米管、二维石墨烯、三维多孔碳材料作为基底形成的一系列金属(氧化物)复合材料,及这些材料在催化和锂离子电池领域中的应用.最后,对超临界二氧化碳沉积方法的应用进行了总结和展望.     

Solvothermal synthesis of flower‐like lanthanum tartrate and lanthanum oxide microspheres in ethanol‐water mixed system

Monodispersed lanthanum tartrate microspheres with flower‐like shape were synthesized by a mild solvothermal method using ethanol‐water mixed system as the solvent. Lanthanum oxide with reserved spherical shape was subsequently fabricated by a following calcination process. X‐ray diffraction analyses (XRD), X‐ray spectroscopy (EDS), scanning electron microscopy (SEM), thermogravimetry‐differential thermal analysis (TG‐DTA) were employed to characterize the composition, structure, and morphology of the products. The lanthanum tartrate microspheres were aggregated by nanosheets as petals. Size of the aggregation and thickness of the petal vary with the vol.% of ethanol. As the vol.% of ethanol increases the degree of aggregation and the thickness of the petal decrease, and other properties such as the size distribution, dispersion are also modulated. These alterations can be interpreted by the changing dielectric constant of mixed solvent. Such lanthanum tartrate can be applied to fabricate micro‐sphereshaped lanthanum oxide after calcination. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of size-controlled acid-resistant hybrid calcium carbonate microparticles as templates for fabricating "micelles-enhanced" polyelectrolyte capsules by the LBL technique

Size-controlled, low-dispersed calcium carbonate microparticles were synthesized in the presence of the amphiphilic block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) by modulating the concentration of block copolymer in the reactive system. This type of hybrid microparticles have acid-resistant properties. By investigating the aggregation behaviors of PS-b-PAA micelles by transmission electron microscopy (TEM), the mechanism of hybrid calcium carbonate formation illustrated that the block copolymer served not only as "pseudonuclei" for the growth of calcium carbonate nanocrystals, but also forms the supramicelle congeries, a spherical framework, as templates for calcium carbonate nanocrystal growth into hybrid CaCO(3) particles. Moreover, this pilot study shows that the hybrid microparticle is a novel candidate as a template for fabricating multilayer polyelectrolyte capsules, in which the block copolymer is retained within the capsule interior after core removal under soft conditions. This not only facilitates the encapsulation of special materials, but also provides "micelles-enhanced" polyelectrolyte capsules.