Coordination compounds of biological interest

The thermal properties of the Cr(III) complexes with the ligands glycine and glutamic acid were determined using TG, DTG and DTA techniques.The chromium(III)-glycine complex is more stable than the chromium(III)-glutamate complex. This behaviour is discussed in terms of different structures by IR and reflectance spectra as well as thermal data.     

Thin film deposition from plasmas of tetramethylsilane–helium–argon mixtures with oxygen and with nitrogen

Films were produced by plasma enhanced chemical vapor deposition (PECVD) of tetramethylsilane (TMS)–helium–argon mixtures with either oxygen or nitrogen in a vacuum system fed with radiofrequency power. Actinometric optical emission spectroscopy was used to determine trends in the concentrations of plasma species of interest (H, CH, O, CO, and CN) as a function of the ratio of the inorganic reactive gas (oxygen or nitrogen) to the monomer (TMS) in the system feed. As the ratio of oxygen to TMS in the feed is increased, the degree of oxygenation of the deposited material, as revealed by transmission infrared spectroscopy, is also increased. Similarly, the degree of nitrogenation of the films increases with increasing nitrogen to monomer ratio in the feed. Strong correlations exist between the plasma concentrations of the above-mentioned plasma species and film structure and composition. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1873–1879, 1998     

Simultaneous Determination of Fenproporex, Diethylpropione and Methylphenidate in Oral Fluid by LC-MS/MS

A liquid chromatography–tandem mass spectrometry method has been developed and validated for confirmation and quantification of three amphetamine-type stimulants (ATS) in oral fluid (OF), namely fenproporex (FEN), diethylpropione (DIE) and methylphenidate (MPH), which are misused by some Brazilian drivers and have potentially dangerous consequences in road traffic. In this method, the OF was extracted by a simple and fast liquid–liquid extraction using acetonitrile. Calibration curves were linear throughout the concentration range from 2.5 to 90 ng mL^?1 in OF, using internal standard. The lower limit of quantification and the limit of detection were 2.5 and 0.5 ng mL^?1, respectively, for all ATS. Intra- and inter-assay precision and accuracy values were within regulatory limits. The analyte extraction presented poor recoveries, but was considered appropriated for analyses of ATS in OF due to the low limits of detection. Matrix effects and carry over were not detected. All analytes were stable during the whole analytical procedure. The present analytical method was considered simple and sensitive for simultaneous determination of FEN, DIE, and MPH in OF and suitable for clinical and forensic toxicology.     

Magnetic nanoparticles and concentrated magnetic nanofluids： Synthesis, properties and some applications

This paper reviews some recent results concerning chemical synthesis of magnetic nanoparticles and preparation of various types of magnetic nanofluids. Structural properties and behaviour in external magnetic field of magnetic nanofluids will be emphasized with relation to their use in leakage-free rotating seals and in biomedical applications.     

Solving systems of equivalentions

We obtain a property of distributivity in the equivalence form overLR fuzzy intervals. As an application and main result of the paper, we give a determinant method to solve systems of linear equivalentions. The expected value of the obtained solution is equal to the corresponding solution of the classical system of linear equations considering the expected values as data.     

Apriori error estimation in terms of the third derivative for the method of successive approximations applied to ODE’S

Here we present a new apriori error estimation for the method of successive approximations applied to ODE’s, using a perturbed trapezoidal quadrature rule. This estimation holds for functions which have continuous and Lipschitzian third order derivatives.     

Pharmaceutically active ionic liquids with solids handling, enhanced thermal stability, and fast release

Pharmaceutically active compounds in ionic liquid form immobilized onto mesoporous silica are stable, easily handled solids, with fast and complete release from the carrier material when placed into an aqueous environment. Depending on specific ion-surface interactions, they may also exhibit improved thermal stability when compared to the non-adsorbed compounds.     

Interaction of (hydroxypropyl) cellulose with anionic surfactants in dilute regime

(Hydroxypropyl)cellulose (HPC) dilute aqueous solutions in the presence of sodium cholate (CS), sodium deoxycholate (DC), and sodium dodecylsulphate (SDS) were investigated. The hydrophobicity parameter (I ₁/I ₃) from fluorescence has shown a critical aggregation concentration (CAC) lower than the critical micellar concentration (CMC). One or two breakpoints were observed in the curve conductivity vs surfactant concentration. The thermodynamic parameters of aggregation (, and ) and the degree of counterion dissociation were calculated. Evidences for the secondary aggregation of CS/water system were found. The relative viscosity increases for HPC/bile salt solutions only at high surfactant concentrations, whereas for HPC/SDS, it passes through a maximum. The cloud points of both HPC/bile salt solutions at higher surfactant concentrations reach a temperature plateau value around 324 K, while for HPC/SDS, it exceeds 373 K at low SDS concentrations. Dynamic light scattering has demonstrated that the surfactants bind to HPC already at concentrations lower than CAC.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Comparative analysis of the structure of sterically stabilized ferrofluids on polar carriers by small-angle neutron scattering

Results of experiments on small-angle neutron scattering from ferrofluids on polar carriers (pentanol, water, methyl-ethyl-ketone), with double-layer sterical stabilization of magnetic nanoparticles, are reported. Several types of spatial structural organization are observed. The structure of highly stable pentanol-based samples is similar to that of stable ferrofluids based on organic non-polar carriers (e.g., benzene) with mono-layer covered magnetic nanoparticles. At the same time, the effect of the interparticle interaction on the scattering is stronger in polar ferrofluids because of the structural difference in the surfactant shell. The structure of the studied methyl-ethyl-ketone- and water-based ferrofluids essentially different from the previous case. The formation of large (>100 nm in size) elongated or fractal aggregates, respectively, is detected even in the absence of external magnetic field, which corresponds to weaker stability of these types of ferrofluids. The structure of the fractal aggregates in water-based ferrofluids does not depend on the particle concentration, but it is sensitive to temperature. A temperature increase results in a decrease in their fractal dimension reflecting destruction of the aggregates. In addition, in water-based ferrofluids these aggregates consist of small (radius approximately 10 nm) and temperature-stable primary aggregates.