Evolution of the nonionic inverse microemulsion-acid-TEOS system during the synthesis of nanosized silica via the sol-gel process.

The cyclohexane-igepal inverse microemulsion, comprehensively established for the synthesis of silica nanoparticles in an ammonia-catalyzed sol-gel process, was alternatively studied with an acid-catalyzed sol-gel process. Tetraethyl orthosilicate (TEOS) was used as the silica precursor, while two different aqueous phases containing either HNO(3) or HCl at two different concentrations, 0.1 and 0.05 M, were examined in the presence and in the absence of NaF, a catalyst of the condensation step. The evolution of the overall reacting system, specifically hydrolysis and polycondensation of reaction intermediates, was monitored in situ by time-resolved small-angle X-ray scattering. No size variation of the inverse micelles was detected throughout the sol-gel process. Conversely, the density of the micellar core increased after a certain time interval, indicating the presence of the polycondensation product. The IR spectra of the reacting mixture were in agreement with such a hypothesis. (1)H and (13)C NMR measurements provided information on the soluble species, the surfactant, and TEOS. The TEOS consumption was well fitted by means of an exponential decay, suggesting that a first-order kinetics for TEOS transpires in the various systems examined, with rate constants dependent not only on the acid concentration but also on its nature (anion specific effect), on the presence of NaF, and on the amount of water in the core of the inverse micelle. The self-diffusion coefficients, determined by means of PGSTE NMR, proved that a sizable amount of the byproduct ethanol was partitioned inside the inverse micelles. Characterization of the final product was carried out by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM), which concurrently confirmed that the silica isolated from the inverse nonionic microemulsion is not significantly different from the product of a bulk acid-catalyzed sol-gel synthesis. TEM micrographs illustrated particles with diameters smaller than the diameter of the inverse micelles as determined by SAXS, due to a shrinkage effect, in addition to nanostructured aggregates in the range 20-100 nm.

[Clinical use of catomas and biotrit in a combined treatment of patients with chronic neurodermatitis]. / Klinicheskoe primenenie Katomasa i Biotrita v kompleksnom lechenii bol'nykh s khronicheskimi formami neirodermita.

In 170 patients with neurodermatitis, therapeutic benefit was studied of two new antioxidant drug preparations catomas (containing beta-carotene and tocopheroli acetas) and biotrit (extractum from the sprouting wheat). Catomas was used in applications to the area of affection with the aid of phonophoresis, biotrit in injections. It has been shown by the studies made that employment of the above drugs combined with sedatives, desensitizing and anti-inflammatory means of remediation enhances efficiency of the treatments administered, which fact was evidenced by the reduction of the mean duration of the treatment undergone by 4.4 days and by 30% increase in the treatment efficiency. Greater benefit from catomas and biotrit will be seen in those patients having been placed on a general treatment.