共查询到20条相似文献,搜索用时 15 毫秒
1.
Georgi Yordanov 《Central European Journal of Chemistry》2012,10(2):305-312
This article considers the preparation and physicochemical characterization of a novel colloidal formulation of the β-lactam
antibiotic cephalexin, loaded in poly(ethyl cyanoacrylate) colloidal nanospheres. The drug was loaded by means of drug incorporation
in the interior of poly(ethyl cyanoacrylate) particles during the polymerization of the respective monomer in aqueous medium.
The obtained colloids were characterized by scanning electron microscopy, dynamic and electrophoretic light scattering, Fourier
transform infrared and nuclear magnetic resonance spectroscopy. It was found that the drug loading efficiency depends on the
initial concentration of monomer and cephalexin in the polymerization medium. The average size of cephalexin-loaded particles
was around 400 nm and did not depend significantly on the concentrations of drug and monomer. Drug-loaded particles with drug
content as high as 21% (w/w) were prepared. The drug release kinetics was studied in physiological phosphate-buffered saline. It was found that a biexponential
model could describe well the experimental release kinetics.
相似文献
2.
Cory C. Pye 《Central European Journal of Chemistry》2011,9(4):567-571
A geometry and SCF convergence study of Hartree-Fock calculations using the 6-31G* basis set is carried out on the set of
all possible diatomic molecules formed from atoms with Z≤36. The utility of Hartree-Fock calculations using the smaller STO-3G
basis set to improve the convergence behavior is demonstrated.
相似文献
3.
Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic
acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of
pH 7.4.
相似文献
4.
Bingcheng Yang Feifang Zhang Xinmiao Liang 《Central European Journal of Chemistry》2012,10(3):472-479
This review summarizes the development of capillary ion chromatography (CIC) over approximately the last 5 years. It mainly
focuses on the technologic aspects of several key components associated with CIC, including micropump, microscale electrodialytic
eluent generator, microscale suppressor and the detector.
相似文献
5.
Nikolai N. Kolesnikov Elena B. Borisenko Dmitrii N. Borisenko Boris A. Gnesin 《Central European Journal of Chemistry》2011,9(4):619-623
In the present study newly produced semiconductor ceramic nanopowder materials made of CdTe and Cd1−xZnxTe (CZT) are considered. Common features and differences in microstructures, phase transformations, grain growth and properties
of the ceramic materials of the binary and ternary compositions are studied.
相似文献
6.
Mi?osz Mi?tkiewski Beata Powa?a Bartosz Staniszewski Maciej Kubicki W?odzimierz Urbaniak Cezary Pietraszuk 《Central European Journal of Chemistry》2011,9(4):728-736
Selected β-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis with selected
olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly with
good yields and selectivities.
相似文献
7.
Dimitra Giasafaki Athanassios Bourlinos Georgia Charalambopoulou Athanassios Stubos Theodore Steriotis 《Central European Journal of Chemistry》2011,9(5):948-952
Metal-carbon composites have shown considerable hydrogen storage potential at room temperature. In the present work the behaviour
of two different Pd amalgam doped carbon substrates, namely a carbogenic foam and a mildly oxidised ordered mesoporous carbon,
are compared on the basis of their hydrogen sorption properties at 77 and 298 K and low pressures, aiming to investigate the
effect of surface on the storage capacity. In both cases, the introduction of alloy nanoparticles leads to an improvement
of the hydrogen uptake with respect to pure carbons. This effect is significant for the carbogenic foam however small for
the ordered carbon.
相似文献
8.
This article describes the simple hydrodehalogenation of halogenated anilines and their derivatives by the action of Raney
aluminium-nickel alloy in aqueous alkaline solution at room temperature. The reaction course was monitored by means of 1H
nuclear magnetic resonance (NMR) spectroscopy and GC-MS spectra.
相似文献
9.
Sushilkumar A. Jadhav 《Central European Journal of Chemistry》2012,10(2):295-299
New symmetrical disulfides together with the corresponding thiols bearing fluorescent end-groups have been synthesized as
building-blocks for self-assembled monolayers (SAMs). The synthesis has been accomplished starting from aromatic nitrogen
heterocycles in three steps. The conversion of the tosylated intermediate into the final disulfide is accomplished by use
of sodium hydrogen sulfide (NaSH). Both products (thiols and disulfides) were isolated and characterized.
相似文献
10.
Dariusz Wyrzykowski Michał Wera Artur Sikorski Dagmara Jacewicz Lech Chmurzyński 《Central European Journal of Chemistry》2011,9(6):1096-1101
The crystal structure of 2-methylpyridinium tetrachloroferrate(III) was determined. The iron cation is tetracoordinated by
chloride anions, and it adopts a slightly distorted tetrahedral coordination with three angles smaller, two almost equal and
one larger than the tetrahedral. The compound is isostructural with its 3-, and 4-methylpyridinium analogues. The thermal
properties of 2-, 3- and 4-methylpyridinium tetrachloroferrates(III) have been studied using TG and DSC techniques. The compounds
exhibit a high stability in the melt.
相似文献
11.
The contemporary status of experimental as well as theoretical advances within the special view of structural phase transitions is reviewed. A brief outline of phase transitions and its classification is presented first. High-pressure experimental techniques developed for studying the structural phase transitions and elastic properties are reviewed. The complete set of theoretical and experimental data obtained is for the group II–IV alkaline earth chalcogenides. Here the authors review the currently used calculations and high-pressure behavior of these materials and the theoretical work that has been done on them. 相似文献
12.
Agnieszka Król-Gracz Ewa Michalak Piotr M. Nowak Agnieszka Dyonizy 《Central European Journal of Chemistry》2011,9(6):982-989
This paper discusses the experimental results of the production of nanocolloidal silver using photoreduction method. Ultrafine
crystalline gelatine-stabilised aqueous suspensions of silver bromide were used as a substrate for the synthesis of silver
nanoparticles (Ag NPs). The influences of the reductant to substrate molar ratio, the medium’s pH, the type of the source of actinic radiation
and the time of exposure to the efficient production of the Ag NPs were studied. A typical reaction was suggested, which involves the photo-induced reduction of silver bromide nanocrystals
in the presence of ascorbic acid under specified physicochemical conditions. The properties of resultant silver particles
were examined using UV-Vis spectroscopy and Dynamic Light Scattering (DLS). In addition, Transmission Electron Microscopy
(TEM) was used for imaging the silver nanoparticle suspensions.
相似文献
13.
M. Teresa Barros Ana I. Mouquinho Krasimira T. Petrova Mara D. Saavedra João C. Sotomayor 《Central European Journal of Chemistry》2011,9(4):557-566
It has been reported that the length of the molecular chain and the rigidity of molecules influence the structure of the polymer
network in PDLC films and hence the electro-optical properties of the composites. Herein, a series of new aromatic monomeric
monomethacrylates, bismethacrylates and monovinylbenzene derivatives with a mesogenic core were successfully synthesized under
microwave irradiation. The microwave assisted synthesis resulted in decreased reaction times, reduced solvent requirement,
increased operational simplicity, and in most cases, improved yields and selectivity.
相似文献
14.
15.
Irena Baranowska Sylwia Magiera Jacek Baranowski 《Central European Journal of Chemistry》2011,9(6):972-981
The aim of this paper is to optimize and validate a high performance liquid chromatography (HPLC) method for separation and
quantification of five isoflavones. A statistical central composite design was used to separate all peaks. These multivariate
procedures were efficient in determining the optimal separation condition using resolution, capacity factor, asymmetry and
number of theoretical plates.
相似文献
16.
D. A. Svechkarev G. V. Karpushina L. L. Lukatskaya A. O. Doroshenko 《Central European Journal of Chemistry》2008,6(3):443-449
Three 2-(benzimidazol-2-yl)-3-hydroxychromone derivatives were synthesized. Their spectroscopic and fluorescent properties,
due to excited state intramolecular proton transfer (ESIPT) from OH to carbonyl, were studied. Theoretical possibility of
an alternative intramolecular H-bonding and experimental evidence for such behavior are discussed.
相似文献
17.
The kinetics of the C-S coupling of arylmagnesium bromides with phenyl tosylate has been studied in THF: toluene at 90°C.
The reaction is first order in Grignard reagent and first order in phenyl tosylate. Kinetic data, Hammett relationship and
activation parameters are consistent with a nucleophilic addition mechanism involving rate determining attack of carbanion
to sulfonyl group followed by a fast phenoxide group leaving.
相似文献
18.
Anuţa Câmpean Mihaela Tertiş Robert Săndulescu 《Central European Journal of Chemistry》2011,9(4):688-700
Electrochemical behaviour of some alkaloids, namely: caffeine, aminophylline, theophylline, codeine phosphate and papaverine
hydrochloride, that are in solution in various combinations or in the presence of other compounds contained in pharmaceuticals
or in real samples (urine) was investigated using cyclic voltammetry (CV), square-wave voltammetry (SWV) and differential
pulse voltammetry (DPV) on electrochemically activated glassy carbon electrode.
相似文献
19.
U. Ceren Başköse Sevgi Haman Bayarı Semran Sağlam Hacı Özışık 《Central European Journal of Chemistry》2012,10(2):395-406
The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single
point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational
frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were
made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate
salts on the geometry of rasagiline free base and its normal modes are also discussed.
相似文献
20.
Mažvydas Mackevičius Feliksas Ivanauskas Aivaras Kareiva 《Central European Journal of Chemistry》2012,10(2):380-385
In our work, we present a method for estimation of the diffusion and reaction rates of synthesis at high temperatures using
limited information from laboratory experiments, such as synthesis time and dimensions of reactants. Synthesis by sol-gel
and solid-state reactions is considered. The inverse modeling problem is solved for one- and two-dimensional models. Explicit
formulas for the diffusion coefficient and reaction rate as functions of temperature are obtained. The activation energies
are calculated, and the lower bounds of diffusion and reaction rates are estimated, thus obtaining conditions for occurrence
of synthesis.
相似文献