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91.
de Souza CA Colombo AP Souto RM Silva-Boghossian CM Granjeiro JM Alves GG Rossi AM Rocha-Leão MH 《Colloids and surfaces. B, Biointerfaces》2011,87(2):310-318
The kinetic of chlorhexidine digluconate (CHXDG) uptake from aqueous solution by hydroxyapatite (HA) was investigated by ultraviolet (UV) analysis performed in HA powder (UV-solid) after the CHX adsorption. Adsorption isotherm of chlorhexidine (CHX) uptake was modeled by a combination of Languimir and Langmuir-Freundlich mechanisms. Strong molecule-molecule interactions and positive cooperativity predominated in the surface when CHX concentration was above 8.6 μg(CHX)/mg(HA). UV-solid spectra (shape, intensity and band position) of CHX bound to HA revealed that long-range molecular structures, such as aggregates or micelles, started to be formed at low CHX concentrations (1.52 μg(CHX)/mg(HA)) and predominated at high concentrations. Grazing-incidence X-ray diffraction (GIXRD) analysis from synchrotron radiation discarded the formation of crystalline structures on HA surface or precipitation of CHX crystalline salts, as suggested in previous works. The effect of the HA/CHX association on HA in vitro bioactivity, cytotoxicity and CHX antimicrobial activity was evaluated. It was shown that CHX did not inhibit the precipitation of a poorly crystalline apatite at HA/CHX surface after soaking in simulating body fluid (SBF). Cell viability studies after exposure to extracts of HA and HA/CHX showed that both biomaterials did not present significant in vitro toxicity. Moreover, HA/CHX inhibited Enterococcus faecalis growth for up to 6 days, revealing that binding to HA did not affect antimicrobial activity of CHX and reduced bacterial adhesion. These results suggested that HA/CHX association could result in a potential adjuvant antimicrobial system for clinical use. 相似文献
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95.
De Moliner F Banfi L Riva R Basso A 《Combinatorial chemistry & high throughput screening》2011,14(9):782-810
The reaction of isocyanides with electron deficient alkynes has been first reported in 1969, about ten years after the first reports on the famous Ugi four component reaction. However it took about thirty years to realise that the zwitterionic intermediate originating from interaction of the two species could be trapped by a third component, thus giving the start to a novel class of isocyanide-based multicomponent reactions. From that first report dated 1996 there has been an ongrowing interest that has produced, so far, about 150 distinct scientific papers. This review is aimed at rationalising and cathegorising these reports and at offering an overview of all the possible applications of this novel methodology. 相似文献
96.
Renata Furtuna Silvia Curteanu Carmen Racles 《Central European Journal of Chemistry》2011,9(6):1080-1095
Polydimethylsiloxane nanoparticles were obtained by nanoprecipitation, using a siloxane surfactant as stabilizer. Two neural
networks and a genetic algorithm were used to optimize this process, by minimizing the particle diameter and the polydispersity,
finding in this way the optimum values for surfactant and polymer concentrations, and storage temperature. In order to improve
the performance of the non-dominated sorting genetic algorithm, NSGA-II, a genetic operator was introduced in this study —
the transposition operator — “real jumping genes”, resulting NSGA-II-RJG. It was implemented in original software and was
applied to the multi-objective optimization of the polymeric nanoparticles synthesis with silicone surfactants. The multi-objective
function of the algorithm included two fitness functions. One fitness function was calculated with a neural network modelling
the variation of the particle diameter on the surfactant concentration, polymer concentration, and storage temperature, and
the other was computed by a neural network modelling the dependence of polydispersity index on surfactant and polymer concentrations.
The performance of the software program that implemented NSGA-II-RJG was highlighted by comparing it with the software implementation
of NSGA-II. The results obtained from simulations showed that NSGA-II-RJG is able to find non-dominated solutions with a greater
diversity and a faster convergence time than NSGA-II.
相似文献
97.
Ilse Fischer Gerald Gruber Franz Rendl Renata Sotirov 《Mathematical Programming》2006,105(2-3):451-469
We propose a dynamic version of the bundle method to get approximate solutions to semidefinite programs with a nearly arbitrary
number of linear inequalities. Our approach is based on Lagrangian duality, where the inequalities are dualized, and only
a basic set of constraints is maintained explicitly. This leads to function evaluations requiring to solve a relatively simple
semidefinite program. Our approach provides accurate solutions to semidefinite relaxations of the Max-Cut and the Equipartition
problem, which are not achievable by direct approaches based only on interior-point methods.
Received: April, 2004
The last author gratefully acknowledges the support from the Austrian Science Foundation FWF Project P12660-MAT. 相似文献
98.
Arwa Kurabi Alex Berlin Neil Gilkes Douglas Kilburn Renata Bura Jamie Robinson Aleksandr Markov Anton Skomarovsky Aleksandr Gusakov Oleg Okunev Arkady Sinitsyn David Gregg Dan Xie John Saddler 《Applied biochemistry and biotechnology》2005,121(1-3):219-230
Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (~44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without β-glucosidase supplementation. 相似文献
99.
Joykrishna Dey A. Yvette Will Rezik A. Agbaria Peter W. Rabideau Atteye H. Abdourazak Renata Sygula Isiah M. Warner 《Journal of fluorescence》1997,7(3):231-236
The spectroscopic properties of corannulene and cyclopentacorannulene are examined by use of absorption and steady-state fluorescence
measurements. A red shift in the emission maxima of cyclopentacorannulene is noted with respect to the emission maxima in
the corannulene spectrum. Similar differences in the absorption spectra of both molecules are also observed. Reasons for the
dissimilarities in the absorption and emission spectra of these molecules are discussed. The fluorescence quantum yields and
lifetimes of the molecules measured in organic solvents are reported. The fluorescence quantum yield and lifetime of cyclopentacorannulene
are lower than those of corannulene. This difference is attributed to the highly strained and nonplanar structure of cyclopentacorannulene.
The effectiveness of nitromethane as a quencher of corannulene and cyclopentacorannulene fluorescence is examined. In contrast
to previously reported results, the fluorescence of these molecules is quenched by nitromethane. Fluorescence quenching of
the molecules has been attributed to complex formation in the ground state, i.e., static quenching. 相似文献
100.
Daniel Vegh Marian Landl Renata Pavlovicova Hans Kuzmany Peter Zalupsky 《Chemistry of Heterocyclic Compounds》1995,31(10):1238-1240
New phihalocyanine analogues were prepared based on 2,5-diamond-3,4-dicyanothiophene and diaminomaleo-nitrile.Department of Organic Chemistry, Slovak Technical University, Bratislava, Slovakia. Institute für Festkörperphysik der Universität Wien, Wien, Austria. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1411, October, 1995. Original article submitted September 24, 1995. 相似文献