ATR-IR studies of CO adsorption from solutions

The formation of strongly bonded carbonaceous species from simple fuels on platinum metal electrodes at open circuit at potentials in the hydrogen region is widely accepted. Attenuated total reflection (ATR)-IR spectroscopy was used in this work to investigate the adsorption of such particles. A platinum film sufficiently stable for such studies in acid solution could be obtained on a germanium reflection element with a 0.5 nm layer of chromium and a 5 nm layer of platinum. The adsorption of CO leads to a strong band at 2000 cm⁻¹ assigned to linearly bonded CO, a broad band at 1800 cm⁻¹ assigned to bridge-bonded and possibly multiple bonded CO and a weak band at 1430 cm⁻. Clearly, the reaction of methanol, formaldehyde or formic acid produces the strong CO band.     

Spectrophotometric determination of olanzapine by its oxidation with N-bromosuccinimide and cerium(IV)sulfate.

Three simple spectrophotometric methods have been described for the assay of olanzapine in its pure and pharmaceutical formulations. The direct method (A) is based on the drug oxidation with excess of N-bromosuccinimide in acidic medium and the two indirect methods (B and C) are based on the oxidation of the drug with excess of N-bromosuccinimide and cerium(IV)sulfate, followed by the reaction of the unconsumed oxidants with celestine blue. The calibration graphs were linear over the range 10 - 120 microg mL(-1) (method A), 0.5 - 6.0 microg mL(-1) (method B) and 0.6 - 3.0 microg mL(-1) (method C). After validation, the proposed methods were successfully applied to assay of olanzapine in its commercial tablets with mean percentage recoveries of 101.23 +/- 0.10, 96 +/- 0.10 and 94 +/- 0.04%. The mechanism of olanzapine oxidation with N-bromosuccinimide was also proposed.     

Long-term results of recurrent laryngeal nerve resection for adductor spasmodic dysphonia

From a total of 43 adductor spasmodic patients over a 10-year period, 11 underwent resection of a portion of the recurrent laryngeal nerve on one side. The initial results were excellent but a varying degree of recurrence took place in 8 patients. In 4, a reoperation was done. At the final follow-up, 2–8 years after the primary operation, 4 patients were no longer suffering from spasmodic dysphonia, another 5 were better off than before surgery, and 1 remained unchanged. Only 1 was worse off. Electromyographic findings indicated that the recurrence of symptoms was due to regeneration of the nerve fibers.     

Decay dynamics of europium excited states in bioactive glasses

Optical probes of solution-produced glasses yield valuable information about the local structure and dynamics of the host glass systems. We report lifetime results for europium excited states in a series of sol–gel-produced bioactive glasses with the composition Ca_xP_0.06Si_0.94?xO₂ (0.11<x<0.35). The excited state lifetimes are very narrowly distributed about a mean value, leading to nearly single exponential decay curves. A rate equation model is used to study the effects of calcium concentration and temperature on the decay rates. While the presence of calcium in the glass samples greatly enhances the luminescence, over the concentration range tested, no significant difference in the decay times was measured. Over the temperature range 77–300 K about 20% and 30% increases in the decay rates of the ⁵D₀ and ⁵D₁ levels were measured, respectively.