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991.
Francesco Napoli Dr. Mario Chiesa Dr. Elio Giamello Prof. Gloria Preda Dr. Cristiana Di Valentin Dr. Gianfranco Pacchioni Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):6776-6785
The formation of O2? radical anions by contact of O2 molecules with a Na pre‐covered MgO surface is studied by a combined EPR and quantum chemical approach. Na atoms deposited on polycrystalline MgO samples are brought into contact with O2. The typical EPR signal of isolated Na atoms disappears when the reaction with O2 takes place and new paramagnetic species are observed, which are attributed to different surface‐stabilised O2? radicals. Hyperfine sublevel correlation (HYSCORE) spectroscopy allows the superhyperfine interaction tensor of O2?Na+ species to be determined, demonstrating the direct coordination of the O2? adsorbate to surface Na+ cations. DFT calculations enable the structural details of the formed species to be determined. Matrix‐isolated alkali superoxides are used as a standard to enable comparison of the formed species, revealing important and unexpected contributions of the MgO matrix in determining the electronic structure of the surface‐stabilised Na+? O2? complexes. 相似文献
992.
Vladimir A. Sivakov Dr. Katja Höflich Michael Becker Dr. Andreas Berger Dr. Thomas Stelzner Dr. Kai‐Erik Elers Dr. Viljami Pore Dr. Mikko Ritala Prof. Dr. Silke H. Christiansen Dr. 《Chemphyschem》2010,11(9):1995-2000
A new method to prepare plasmonically active noble metal nanostructures on large surface area silicon nanowires (SiNWs) mediated by atomic layer deposition (ALD) technology has successfully been demonstrated for applications of surface‐enhanced Raman spectroscopy (SERS)‐based sensing. As host material for the plasmonically active nanostructures we use dense single‐crystalline SiNWs with diameters of less than 100 nm as obtained by a wet chemical etching method based on silver nitrate and hydrofluoric acid solutions. The SERS active metal nanoparticles/islands are made from silver (Ag) shells as deposited by autometallography on the core nanoislands made from platinum (Pt) that can easily be deposited by ALD in the form of nanoislands covering the SiNW surfaces in a controlled way. The density of the plasmonically inactive Pt islands as well as the thickness of noble metal Ag shell are two key factors determining the magnitude of the SERS signal enhancement and sensitivity of detection. The optimized Ag coated Pt islands on SiNWs exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability and reproducibility. The plasmonic activity of the core‐shell Pt//Ag system that will be experimentally realized in this paper as an example was demonstrated in numerical finite element simulations as well as experimentally in Raman measurements of SERS activity of a highly diluted model dye molecule. The morphology and structure of the core‐shell Pt//Ag nanoparticles on SiNW surfaces were investigated by scanning‐ and transmission electron microscopy. Optimized core–shell nanoparticle geometries for maximum Raman signal enhancement is discussed essentially based on the finite element modeling. 相似文献
993.
Sebastian Kopitzki Dipl.‐Chem. Knud J. Jensen Prof. Dr. Joachim Thiem Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):7017-7029
In recent years the interest in tools for investigating carbohydrate–protein (CPI) and carbohydrate‐carbohydrate interactions (CCI) has increased significantly. For the investigation of CPI and CCI, several techniques employing different linking methods are available. Surface plasmon resonance (SPR) imaging is a most appropriate tool for analyzing the formation of self‐assembled monolayers (SAM) of carbohydrate derivatives, which can mimic the glycocalyx. In contrast to the SPR imaging methods used previously to analyze CPI and CCI, the novel approach reported herein allows a facile and rapid synthesis of linker spacers and carbohydrate derivatives and enhances the binding event by controlling the amount and orientation of ligand. For immobilization on biorepulsive amino‐functionalized SPR chips by reductive amination, diverse aldehyde‐functionalized glycan structures (glucose, galactose, mannose, glucosamine, cellobiose, lactose, and lactosamine) have been synthesized in several facile steps that include olefin metathesis. Effective immobilization and the first binding studies are presented for the lectin concanavalin A. 相似文献
994.
Ulyana Angel? Devorah Matas Dr. Shulamit Michaeli Prof. Artur Cavaco‐Paulo Prof. Aharon Gedanken Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2108-2114
This paper describes the synthesis of mixed proteinaceous microspheres (MPMs) by the sonochemical method. The current fundamental research follows the research of Suslick and co‐workers who have developed a method by which high‐intensity ultrasound is used to make aqueous suspensions of proteinaceous microcapsules filled with water‐insoluble liquids. 1 By using high‐intensity ultrasound, we have synthesized microspheres made of a few different proteins. The three proteins used in the current experiments are bovine serum albumin (BSA), green fluorescent protein (GFP), and cyan fluorescent protein–glucose binding protein–yellow fluorescent fused protein (CFP‐GBP‐YFP). The two synthesized microspheres made of mixed proteins are BSA‐GFP and BSA‐(CFP‐GBP‐YFP). This paper presents the characterization of the sonochemically produced microspheres of mixed proteins. It also provides an estimate of the efficiency of the sonochemical process in converting the native proteins to microspheres. 相似文献
995.
Zhanfeng Zheng Dr. Jaclyn Teo Xi Chen Dr. Hongwei Liu Dr. Yong Yuan Dr. Eric R. Waclawik Dr. Ziyi Zhong Dr. Huaiyong Zhu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1202-1211
Three catalytic oxidation reactions have been studied: The ultraviolet (UV) light induced photocatalytic decomposition of the synthetic dye sulforhodamine B (SRB) in the presence of TiO2 nanostructures in water, together with two reactions employing Au/TiO2 nanostructure catalysts, namely, CO oxidation in air and the decomposition of formaldehyde under visible light irradiation. Four kinds of TiO2 nanotubes and nanorods with different phases and compositions were prepared for this study, and gold nanoparticle (Au‐NP) catalysts were supported on some of these TiO2 nanostructures (to form Au/TiO2 catalysts). FTIR emission spectroscopy (IES) measurements provided evidence that the order of the surface OH regeneration ability of the four types of TiO2 nanostructures studied gave the same trend as the catalytic activities of the TiO2 nanostructures or their respective Au/TiO2 catalysts for the three oxidation reactions. Both IES and X‐ray photoelectron spectroscopy (XPS) proved that anatase TiO2 had the strongest OH regeneration ability among the four types of TiO2 phases or compositions. Based on these results, a model for the surface OH group generation, absorption, and activation of molecular oxygen has been proposed: The oxygen vacancies at the bridging O2? sites on TiO2 surfaces dissociatively absorb water molecules to form OH groups that facilitate adsorption and activation of O2 molecules in nearby oxygen vacancies by lowering the absorption energy of molecular O2. A new mechanism for the photocatalytic formaldehyde decomposition with the Au/TiO2 catalysts is also proposed, based on the photocatalytic activity of the Au‐NPs under visible light. The Au‐NPs absorb the light owing to the surface plasmon resonance effect and mediate the electron transfers that the reaction needs. 相似文献
996.
Taejoon Kang Ilsun Yoon Dr. Jangbae Kim Hyotcherl Ihee Prof. Bongsoo Kim Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1351-1355
We report a new type of molecular sensor using a Au nanowire (NW)–Au nanoparticles (NPs) conjugated system. The Au NW–NPs structure is fabricated by the self‐assembly of biotinylated Au NPs on a biotinylated Au NW through avidin; this creates hot spots between NW and NPs that strongly enhance the Raman signal. The number of the Au NPs attached to the NW is reproducibly proportional to the concentration of the avidin, and is also proportional to the measured surface‐enhanced Raman scattering (SERS) signals. Since this well‐defined NW–NPs conjugated sensor is only a few micrometer long, we expect that development of multiplex nanobiosensor of a few tens micrometer size would become feasible by combining individually modified multiple Au NWs together on one substrate. 相似文献
997.
Dr. Hideya Kawasaki Teruyuki Yao Takashi Suganuma Kouji Okumura Dr. Yuichi Iwaki Prof. Tetsu Yonezawa Tatsuya Kikuchi Prof. Ryuichi Arakawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(35):10832-10843
We report a new and facile method for synthesizing 3D platinum nanoflowers (Pt Nfs) on a scratched silicon substrate by electroless galvanic displacement and discuss the applications of the Pt Nfs in surface‐assisted laser desorption/ionization‐mass spectrometry (SALDI‐MS). Surface scratching of n‐type silicon is essential to induce Pt Nf growth on a silicon substrate (to obtain a Pt Nf silicon hybrid plate) by the galvanic displacement reaction. The Pt Nf silicon hybrid plate showed excellent SALDI activity in terms of the efficient generation of protonated molecular ions in the absence of a citrate buffer. We propose that the acidity of the Si? OH moieties on silicon increases because of the electron‐withdrawing nature of the Pt Nfs; hence, proton transfer from the Si? OH groups to the analyte molecules is enhanced, and finally, thermal desorption of the analyte ions from the surface occurs. Signal enhancement was observed for protonated molecular ions produced from a titania nanotube array (TNA) substrate on which Pt nanoparticles had been photochemically deposited. Moreover, surface modification of the Pt Nf silicon hybrid plate by perfluorodecyltrichlorosilane (FDTS) (to obtain an FDTS‐Pt Nf silicon hybrid plate) was found to facilitate soft SALDI of labile compounds. More interestingly, the FDTS‐Pt Nf silicon hybrid plate acts 1) as a high‐affinity substrate for phosphopeptides and 2) as a SALDI substrate. The feasibility of using the FDTS‐Pt Nf silicon hybrid plate for SALDI‐MS has been demonstrated by using a β‐casein digest and various analytes, including small molecules, peptides, phosphopeptides, phospholipids, carbohydrates, and synthetic polymers. The hybridization of Pt Nfs with a scratched silicon substrate has been found to be important for achieving excellent SALDI activity. 相似文献
998.
999.
Daan Wouters Dr. Stephanie Hoeppener Dr. Ulrich S. Schubert Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1732-1739
Surfaces with purposes : The electroinitiated patterning of self‐assembled monolayers enables the fabrication of a variety of complex nanostructures (see picture). The possibilities offered by the introduction of chemical selectivity through the local generation of chemically active groups and subsequent derivatization are reviewed, with a focus on progress in this area of research over the last four years.
1000.
采用自旋极化的密度泛函理论(DFT)对正交与六方的Fe2C晶体体相与表面性质进行了研究,计算了晶胞的聚合能、磁矩以及低指数晶面的表面能。研究结果表明,两种晶型Fe2C 的磁性质相似,但正交堆积的Fe2C比六方堆积的Fe2C更稳定。正交晶系Fe2C低指数晶面的稳定性以 (011) > (110) > (100) > (101) > (001) 顺序降低。对一系列碳化程度不同的碳化铁最稳定表面(Fe2C(011)、Fe3C(001)和Fe4C(100))表面能的比较显示,碳化铁表面的相对稳定性与碳化度非线性相关。另外,与面心立方(BCC)铁最稳定表面(110)相比,Fe2C、Fe3C及Fe4C晶体最稳定表面具有较低的表面能,表明铁表面碳化在热力学上是有利的。 相似文献