Diols and anions can control the formation of an exciplex between a pyridinium boronic acid with an aryl group connected via a propylene linker

The exciplex formation between a pyridinium boronic acid and phenyl group connected via a propylene linker can be monitored using fluorescence. Addition of pinacol affords a cyclic boronate ester with enhanced Lewis acidity that increases the strength of its cation-pi stacking interaction causing a four-fold fluorescence enhancement.Royal Society ; University of Xiamen ; University of Birmingham ; University of Bath ; China Scholarship Council (CSC

Assembly of N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer films with catechol sensing selectivity

The highly water insoluble N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate is synthesised and investigated for sensor applications. This amphiphilic molecule is immobilised by evaporation of an acetonitrile solution at a basal plane pyrolytic graphite (HOPG) electrode surface and is shown to provide a monolayer film. By varying the amount of deposit partial or full coverage can be achieved. The N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer acts as an active receptor for 1,2-dihydroxy-benzene (catechol) derivatives in aqueous media. The ability to bind alizarin red S is investigated and the Langmuirian binding constant determined as a function of pH. It is shown that the immobilised boronic acid monolayer acts as sensor film for a wider range of catechols. A comparison of Langmuirian binding constants for alizarin red S (1.4 x 10(5) mol(-1) dm(3)), catechol (8.4 x 10(4) mol(-1) dm(3)), caffeic acid (7.5 x 10(4) mol(-1) dm(3)), dopamine (1.0 x 10(4) mol(-1) dm(3)), and L-dopa (8 x 10(3) mol(-1) dm(3)) reveals that a combination of hydrophobicity and electrostatic interaction causes considerable selectivity effects.China Scholarship Counci

A General Route to Diverse Mesoporous Metal Oxide Submicrospheres with Highly Crystalline Frameworks

通讯作者地址: Wang, JF (通讯作者), Chinese Univ Hong Kong, Dept Phys, Shatin, Hong Kong Peoples R China 地址: 1. Chinese Univ Hong Kong, Dept Phys, Shatin, Hong Kong Peoples R China 2. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected], [email protected] NSF 0233728 NASA URETI NCC-1-02037 HK RGC Research 2060332 NSFC/RGC joint Research Scheme N_CUHK448/06 290031

Catalytically active gold on ordered titania supports

Almost two decades have passed since supported An nanoparticles were found to be active for CO oxidation. This discovery inspired extensive research addressing the origin of the unique properties of supported Au nanoparticles, the design and synthesis of potentially technical An catalysts, and the extension of An catalysis to other reactions. This tutorial review summarises the current understanding of the origin of the unique properties of titania-supported ALL catalysts for carbon monoxide oxidation. The key issues of catalysis by nanostructured An, effects of oxide support and active site/structure, especially those provided from model studies are discussed in detail. The successful synthesis of a highly catalytically active gold bilayer may lead to the design and synthesis of practically active Au nanofilm catalysts.Department of Energy ; Office of Basic Energy ; Division of Chemical Sciences ; Robert A. Welch Foundatio

Promotional Effects of Au in Pd-Au Catalysts for Vinyl Acetate Synthesis

Silica Supported Pd-Au bimetallic catalysts are highly selective for the acetoxylation of ethylene to vinyl acetate (VA). In this study we have used model catalysts consisting of planer surfaces and supported nanoparticles to investigate the promotional effects of Au in Pd-Au bimetallic catalysts. Low energy ion scattering spectroscopy, low energy electron diffraction, X-ray photoelectron spectroscopy, infrared reflection adsorption spectroscopy, and temperature-programmed desorption et al, were used to characterize the model systems. The catalytic performance for acetoxylation of ethylene to VA was examined for these model surfaces. In this paper, We summarize the Current understanding of the promotional effects of Au in Pd-Au bimetallic catalysts for VA synthesis. The key results are that An atoms break contiguous Pd atom ensembles at the surface into isolated Pd monomers. The absence of contiguous Pd sites significantly reduces the formation of combustion by-products and Suppresses the poison effects of CO, thus enhancing the VA formation selectivity and activity.Department of Energy, Office of Basic Energy, Division of Chemical Science ; Robert A. Welch Foundatio

INFLUENCE OF LINEAR ALKYLBENZENE SULFONATE (LAS) AS ORGANIC COSOLVENT ON LEACHING BEHAVIOR OF PCDD/FS FROM FLY-ASH AND SOIL

The leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was measured in soil and standard fly ash column eluted with pure water and linear alkylbenzene sulfonate (LAS)- water. The data obtained were used to evaluate the leachability of PCDD/Fs from waste dump like incineration residual slag and fly ash deposition. The leaching rate was shown to be increased significantly by using LAS water. The leachate contents of PCDD/Fs were above their known water solubility. Concentration of PCDD/Fs in the leachates as well as the relative leaching (calculated on the fly ash content) increased with increasing chlorinating degree and decreasing water solubility. LAS above the critical micelle concentration (CMC) probably enhances PCDD/Fs solubility

A general synthetic strategy for oxide-supported metal nanoparticle catalysts

通讯作者地址: Stucky, GD (通讯作者), Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 地址: 1. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected]

Promoting gold nanocatalysts in solvent-free selective aerobic oxidation of alcohols

通讯作者地址: Stucky, GD (通讯作者), Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 地址: 1. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected] trace amount of metal carbonate, acetate or borate significantly boosts gold nanocatalysts in selective aerobic oxidation of alcohols under mild solvent-free conditions

CRYSTAL ORIENTATION EFFECTS DURING FABRICATION OF SINGLE OR MULTI-CRYSTAL NB SRF CAVITIES*

Abstract Single and large-grain Nb SRF cavities are of interest due to possible reduction of cost and problems associated with inconsistent texture and surface finish among batches of rolled polycrystalline Nb sheet. The effect of crystal orientation on dislocation density, surface quality, and recrystallization after plastic deformation and e-beam welding was investigated, as understanding of their interrelations is needed. These were evaluated for three samples of different orientations at steps similar to those in typical cavity forming, with deformation modeled using a crystal plasticity approach. Initial dislocation density was higher than expected, increased with deformation, after welding was reduced in recovered areas, and was similar to initial density in recrystallized grains; there was also evidence that Nb has a higher tolerance for dislocations than other metals. Surface quality depends on a complex relation of crystal orientation, slip system activity, and prior surface treatment. Recrystallization nucleated outside the melt pool, and the new orientations grew both epitaxially into the weld as it solidified, and away until heat and time were insufficient to continue growth

Cutaneous lupus erythematosus after treatment with paclitaxel and bevacizumab for metastatic breast cancer: a case report

Abstract Introduction The monoclonal anti-vascular endothelial growth factor antibody bevacizumab is increasingly used in the treatment of several malignant tumors. The usual side effects of this drug are hypertension and proteinuria. Paclitaxel is widely used in the treatment of breast cancer and head and neck carcinomas. Neither of these two drugs typically causes skin disorders. Paclitaxel-related cutaneous lupus erythematosus has been described before, but in earlier cases patients had a history of autoimmune disease. Case presentation We report a case of a 65-year-old Caucasian woman who presented with cutaneous lupus erythematosus after receiving paclitaxel-bevacizumab combination treatment as first-line therapy for metastatic breast cancer. Her cutaneous symptoms and increased serum anti-SSA and anti-SSB antibodies disappeared shortly after the discontinuation of therapy. Conclusion We conclude that cutaneous lupus erythematosus can also be seen in patients without earlier anamnesis of autoimmune disorders and that, furthermore, bevacizumab might cause atypical cutaneous side effects.</p