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141.
142.
Charles M. Buchanan Norma L. Buchanan Kevin J. Edgar Michael G. Ramsey 《Cellulose (London, England)》2007,14(1):35-47
The solubilities of voriconazole, ketoconazole, and clotrimazole with and without hydroxybutenyl-β-cyclodextrin (HBenBCD)
in aqueous media were examined. The solubility of these antifungal drugs was significantly improved by complexation with HBenBCD.
Both the pH and the type of buffer used to adjust the medium pH had a very significant effect on drug solubilities and the
apparent binding constants of the drug:cyclodextrin complexes. Additionally, the stereochemistry of tartrate buffers was found
to influence both the electrostatic interaction between drug and tartrate as well as complexation of the drug-tartrate aggregate
by HBenBCD. We also compared the solubilization of these antifungal drugs by HBenBCD to other cyclodextrin derivatives with
different substituents under identical experimental conditions and found that the amount of drug solubilized was in some cases
influenced strongly by the nature of the cyclodextrin. Solid antifungal drug:HBenBCD complexes were prepared and their dissolution
profiles were obtained which showed that HBenBCD improved both the rate of dissolution and the amount of drug dissolved. 相似文献
143.
Search for memory effects in methane hydrate: structure of water before hydrate formation and after hydrate decomposition 总被引:1,自引:0,他引:1
Buchanan P Soper AK Thompson H Westacott RE Creek JL Hobson G Koh CA 《The Journal of chemical physics》2005,123(16):164507
Neutron diffraction with HD isotope substitution has been used to study the formation and decomposition of the methane clathrate hydrate. Using this atomistic technique coupled with simultaneous gas consumption measurements, we have successfully tracked the formation of the sI methane hydrate from a water/gas mixture and then the subsequent decomposition of the hydrate from initiation to completion. These studies demonstrate that the application of neutron diffraction with simultaneous gas consumption measurements provides a powerful method for studying the clathrate hydrate crystal growth and decomposition. We have also used neutron diffraction to examine the water structure before the hydrate growth and after the hydrate decomposition. From the neutron-scattering curves and the empirical potential structure refinement analysis of the data, we find that there is no significant difference between the structure of water before the hydrate formation and the structure of water after the hydrate decomposition. Nor is there any significant change to the methane hydration shell. These results are discussed in the context of widely held views on the existence of memory effects after the hydrate decomposition. 相似文献
144.
Kidder MK Britt PF Zhang Z Dai S Buchanan AC 《Chemical communications (Cambridge, England)》2003,(22):2804-2805
A new method for derivatizing mesoporous silicas, SBA-15 and MCM-41, with a substituted phenol is described, and pore confinement and surface curvature are shown to impact the reaction rate and product selectivity for the pyrolysis of surface-immobilized 1,3-diphenylpropane. 相似文献
145.
Boena Novosel Edward B. Buchanan Jr. 《Fresenius' Journal of Analytical Chemistry》1972,262(2):100-101
Summary A square-wave polarograph [3] has been used to determine trace amounts of copper in potable water and in Iowa River water. By using a combination of sodium chloride (1.0 M) and perchloric acid (0.07 M) as a supporting electrolyte under acidic conditions (pH<1), 2 ppb copper could be determined in the samples without and with preconcentration. Copper in the samples was determined with reproducibility of ± 0.13 ppb and so this technique is more reliable than a more used determination of complex salts by atomic absorptionspectrophotometry.
Bestimmung von Spuren Kupfer in Wasser durch Square-Wave-Polarographie
Zusammenfassung Ein früher [3] beschriebener Square-Wave-Polarograph wurde zur Spurenbestimmung von Kupfer in Trink- und Flußwasser (Iowa River) benutzt. Der verwendete Grundelektrolyt war 1,0 M an NaCl und 0,07 M an HClO4 (pH<1). Noch 2 ppb Cu konnten mit und ohne Vorkonzentrierung bestimmt werden. Die Reproduzierbarkeit war ± 0,13 ppb. Das Verfahren ist zuverlässiger als die Bestimmung über Komplexsalze durch Atomabsorptionsspektrophotometrie.
One of the authors wishes to thank Prof. Dr. F. Duke for the acception at the University of Iowa and Prof. Dr. B. Teak for the discussion. 相似文献
146.
Robert Hettich Michelle Buchanan 《Journal of the American Society for Mass Spectrometry》1991,2(5):402-412
Matrix-assisted UV laser desorption Fourier transform mass spectrometry (266 nm, nicotinic acid matrix) can be used for the detailed structural characterization of normal and modified oligonucleotides. The negative ion spectra for these compounds revealed abundant (M ? H) - ions as well as fragment ions that provided the information necessary to determine oligomer sequence and to differentiate isomers. The nicotinic acid matrix was required for the production of (M ? H) - ions for the oligonucleotide dimers, trimers, tetramers, and hexamers examined in this study. Elimination of the nicotinic acid matrix resulted in complete loss of the (M ?H) - ions as well as most of the larger fragment ions for the oligomers. The primary fragmentation pathway was observed to be phosphate ester bond cleavage with the resulting charge retained on the 3’ end of the oligomer and enabled isomeric differentiation of compounds such as d(S’-CGCG-3’) and d(S’-CCGG-3’). Collisioninduced dissociation experiments of the (M ? H) - ions for these compounds confirmed the preferential loss of nucleotides from the 5’ end of the oligomers. The presence and location of modifications such as methyl and ethyl alkyl groups to the oligonucleotides could also be identified. 相似文献
147.
Zlotin SG Kislitsin PG Samet AV Serebryakov EA Konyushkin LD Semenov VV Buchanan AC Gakh AA 《The Journal of organic chemistry》2000,65(25):8430-8438
Reactions of 1-R-2,4,6-trinitrobenenes (R = alkyl, protected aldehyde, aminocarbonyl, cyano groups, or isoxazole ring) with thiol salts were investigated. In most cases, these reactions gave a mixture of minor para and major ortho substitution products. Reactions of N,N-disubstituted 2,4,6-trinitrobenzamides with S-,O-, and N-nucleophiles afforded products of substitution of the p-nitro group exclusively. 1-Cyano-2,4,6-trinitrobenzene was found to be the most reactive and the least selective: all three nitro groups can be substituted using an excess of thiol salts. 2-R-4, 6-dinitrobenzamides showed no regioselectivity under similar conditions to yield 1:1 mixtures of para and ortho isomers. 相似文献
148.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnes AV Barnett BA Bauer DA Bengtsson H Bintinger DL Blumenfeld BJ Bobbink GJ Bross AD Buchanan CD Buijs A Cain MP Caldwell DO Chamberlain O Chien C Clark AR Cowan GD Crane DA Dahl OI Derby KA Eastman JJ Eberhard PH Eisner AM Enomoto R Erne FC Fujii T Gabioud B Gary JW Gorn W Hauptman JM Hofmann W Huth JE Hylen J Joshi UP Kamae T Kaye HS Kees KH Kenney RW Kerth LT Ko W Koda RI Kofler RR Kwong KK Lander RL Langeveld WG Layter JG 《Physical review letters》1986,57(1):51-54
149.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnett BA Bauer DA Bay A Bengtsson H Bobbink GJ Buchanan CD Buijs A Caldwell DO Chao H Chun S Clark AR Cowan GD Crane DA Dahl OI Daoudi M Derby KA Eastman JJ Eberhard PH Edberg TK Eisner AM Enomoto R Erné FC Fairfield KH Hauptman JM Hofmann W Hylen J Kamae T Kaye HS Kenney RW Khacheryan S Kofler RR Langeveld WG Layter JG Lin WT Linde FL Loken SC Lu A Lynch GR Madaras RJ Magnuson BD Masek GE Mathis LG Matthews JA Maxfield SJ 《Physical review letters》1988,60(23):2355-2358
150.
Bonner BE Buchanan JA Carey DC Clement JM Coleman RN Corcoran MD Cossairt JD Derevshchikov AA Grosnick DP Hill DA Imai K Lehar F de Lesquen A Lopiano D Luehring FC Kruk JW Kuroda K Maki T Makino S Masaike A Matulenko YA Meshchanin AP Michalowicz A Miettinen HE Miller DH Miyake K Mohammadzadeh AH Mutchler GS Nagamine T Nessi-Tedaldi F Nessi M Nurushev SB Nguyen C Ohashi Y Pauletta G Penzo A Phillips GC Read AL Roberts JB van Rossum L Salvato G Schiavon P Shima T Solovyanov VL Spinka HM 《Physical review letters》1988,61(17):1918-1921