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131.
Brunella Cappello Clelia Di Maio Maria Iervolino 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(3-4):251-257
The interactions of Bendazac, a topical non-steroidal anti-inflammatory drug, with-cyclodextrin, hydroxypropyl--cyclodextrin and -cyclodextrinwere investigated to evaluate possibilities to improve the drug's poor water solubilityand eventually to enhance the topical delivery of Bendazac. Phase solubility studiesdemonstrated the ability of the selected cyclodextrins to complex with Bendazac andincrease drug solubility. The amount of solubilized Bendazac increased linearly withthe addition of each cyclodextrin according toAL type plots. 13C-NMR studiesshowed that the Bendazac A-ring was included in the cavity of the three cyclodextrins.The -cyclodextrin was also able to include the B-ring of Bendazac, forminga complex where one drug molecule fitted into two cyclodextrin molecules. Equimolarsolid systems of the drug with each cyclodextrin carrier were prepared using varioustechniques (physical mixing, spray-drying and freeze-drying). The results of differential scanning calorimetry and Fourier transform infrared analysis, performed on the solid systems, demonstrated that freeze-dried and spray-dried products had a high degree of amorphization and agreed with the hypothesis of the existence of drug–cyclodextrin interaction in the solid state. The cyclodextrins tested were able to improve the dissolution of Bendazac. The dissolution profile of the drug was also affected by the physico-chemical properties of each solid system, the freeze-dried products being the most rapidly dissolving forms. 相似文献
132.
以结晶紫与亚硝基R盐吸光光度法测定镍 总被引:2,自引:2,他引:2
在氨性(PH9-9.5)条件下,镍(Ⅱ)与结晶紫及亚硝基R盐反应形成紫色络合物,表观摩尔吸光系数ε536=2.29×10^5L,mol^-1,镍浓度在0.0120mg/L范围内遵守比耳定律,组成摩尔比为Ni:CV:R=1:2:1,本法快速,为光度测定微量镍的高灵敏方法之一,用于土壤、人发等试样中镍的测定、结果满意。 相似文献
133.
Tadatomi Nishikubo Atsushi Kameyama Jun Yamashita Takahiro Fukumitsu Chika Maejima Masao Tomoi 《Journal of polymer science. Part A, Polymer chemistry》1995,33(7):1011-1017
The addition reaction of oxiranes ( 15a-d ) with carbon dioxide (CO2) was carried out using 1 mol % of soluble polymer-supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a-d with CO2 proceeded very smoothly to give the corresponding five-membered cyclic carbonates ( 16a-d ) in high yields at 90-100°C. The catalytic activity of the soluble polymer-supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer-supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc. 相似文献
134.
Synthesis and antimicrobial activity of a perfluoroalkyl-containing quaternary ammonium salt 总被引:1,自引:0,他引:1
A novel perfluoroalkyl-containing quaternary ammonium salt 5 was designed and synthesized. Consequently, the antimicrobial activities of compound 5 were measured with Escherichia coli 8099 as a Gram-negative strain and Staphylococcus aureus ATCC 6538 as a Gram-positive strain. Both the minimum inhibitory concentration (MIC, the lowest concentration of compound 5 that inhibits microbial growth) values of quaternary ammonium salt 5 against Escherichia coli 8099 and Staphylococcus aureus ATCC 6538 were 7.8 μg/ml. 相似文献
135.
We describe and interpret computer simulations of the time evolution of a binary alloy on a cubic lattice, with nearest neighbor interactions favoring like pairs of atoms. Initially the atoms are arranged at random; the time evolution proceeds by random interchanges of nearest neighbor pairs, using probabilities compatible with the equilibrium Gibbs distribution at temperatureT. For temperatures 0.59Tc, 0.81 Tc, and 0.89T
c, with density of A atoms equal to that in the B-rich phase at coexistence, the density C1 of clusters ofl A atoms approximately satisfies the following empirical formulas: C1 w(1 –)3 andC
1, (1 –)4Q1w1 (2 l 10). Herew is a parameter and we defineQ
l
=
K
e
–E(K)
, where the sum goes over all translationally nonequivalentl-particle clusters andE(K) is the energy of formation of the clusterK. Forl > 10,Q
1 is not known exactly; so we use an extrapolation formulaQ
l
Aw
s
–l
l
– exp(–bl
), wherew
s is the value ofw at coexistence. The same formula (withw > w
s) also fits the observed values of C, (for small values ofl) at densities greater than the coexistence density (forT=0.59Tc): When the supersaturation is small, the simulations show apparently metastable states, a theoretical estimate of whose lifetime is compatible with the observations. For higher supersaturation the system is observed to undergo a slow process of segregation into two coexisting phases (andw therefore changes slowly with time). These results may be interpreted as a more quantitative formulation (and confirmation) of ideas used in standard nucleation theory. No evidence for a spinodal transition is found.Supported by AFOSR Grant No. 73-2430D and by ERDA Contract No. EY-76-C-02-3077*000. 相似文献
136.
A combined method for determination of the standard enthalpies of formation of nitroform and its salts was proposed. The enthalpies
of dissolution of nitroform and its ammonium, hydrazinium, guanidinium, and potassium salts in water were measured. The enthalpy
of combustion of hydrazinium salt of nitroform was determined by a combustion calorimetry, and its standard enthalpy of formation
was calculated. The enthalpy of formation of trinitromethyl anion in indefinitely diluted aqueous solution −24.94±0.79 kJ
mol−1, was calculated on the basic of the data obtained for enthalpies of formation and dissolution of ammonium and hydrazinium
salts of nitroform. Standard enthalpies of formation of nitroform and its salts were calculated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2451–2454, December, 1998. 相似文献
137.
57Fe Mossbauer spectroscopy was used to investigate the evolution of Fe-Zn binary metal oxide sorbent in the process of high-temperature fuel gas desulfurization. The results of phase analyses show that Fe-Zn binary metal oxide sorbent is rapidly reduced in hot fuel gas and decomposed to new phases of highly dispersed microcrystalline elemental iron and zinc oxide, both of which become the active desulfurization constituents. A complementary and synergistic effect between active iron acting as a high sulfur capacity constituent and active zinc oxide acting as a deep refining desulfurization constituent exists in this type of sorbent for hot fuel gas desulfurization. 相似文献
138.
《Tetrahedron》2003,59(16):2801-2809
A series of furan C-nucleosides having a sulfur atom in the sugar ring were synthesised. The α and β anomers of 3-ethoxycarbonyl-2-methyl-5-(4′-thio-d-erythrofuranosyl)furans 10 and 11 were obtained by acid treatment of (4′-S-acetyl-4′-thio-d-arabino-tetritol-1-yl)furan 9. Oxidation of 10 with m-chloroperbenzoic acid gave sulfoxide 12 as one epimer at the sulfur atom whereas 11 was transformed into sulfoxide 13 as an epimeric mixture. S-Methylation of 10 and 11 with methyl triflate led to sulfonium salts 14 and 15. The prepared compounds were found to be moderate inhibitors of α-l-fucosidase. 相似文献
139.
Compared to the general ionic liquids (ILs), a significant deviation of the binary mixtures of 1-decyl-3-methylimidazolium tri(hexafluoroacetylaceto)-copper(II) ([C10mim][Cu(hfacac)3]) with methanol was found, indicating the way methanol interacts with ILs might be governed by the special structure of the chelating anion. IR results showed that the (C2-H) of 1-decyl-3-methylimidazolium hexafluoroacetylacetonate ([C10mim][hfacac]) blue-shifted more significantly than that of [C10mim][Cu(hfacac)3], meanwhile the (C=O) red-shifted in [C10mim][Cu(hfacac)3], which is contrast with that in [C10mim][hfacac]. Two-dimensional correlation analysis of the FTIR spectra indicated that the chelating cavity has little effect on the sequence of the ILs sites that interact with methanol. Combined with small angle X-ray scattering (SAXS) results, the picture of mixing processes in these two systems were proposed. Methanol interacts directly with the anion followed by the cation in [C10mim][hfacac], while methanol preferentially enters the chelating cavity and enhances the packing effect in the [C10mim][Cu(hfacac)3] system. 相似文献
140.
Masahisa Kakiuchi 《Journal of solution chemistry》1994,23(10):1073-1087
The D/H ratios of hydrogen gas in equilibrium with aqueous sodium chloride solutions of 2, 4 and 6 molalities were determined within the range 10 to 95°C, using a hydrophobic platinum catalyst. With each of the different sodium chloride concentrations, the hydrogen isotope effect between the solution and pure water changes linearly with the square of the reciprocal temperature. On the basis of the results for hydrogen isotope fractionation observed in this study, and those of hydrogen isotope fractionation between pure water and vapor, it is concluded that the structure of the aqueous sodium chloride solution does not change significantly with temperature. The hydrogen isotope effect is evidently different from the results of vapor pressure isotope effects (VPIE) on sodium chloride solutions measured on separated isotopes. The difference between the present work and the VPIE studies is probably due to a non-ideal behavior in a mixture of isotopic water molecules and/or to a H2O-D2O disproportionation reaction in sodium chloride solutions. The distinction between the latter two mechanisms can not be differentiated at present. 相似文献