Mössbauer analysis of recent ceramic finds from Chavin

A large number of ceramic sherds from Chavin, Peru, as well as recent clay samples from the same region have been studied by Mössbauer spectroscopy. The changes of the Mössbauer spectra of the clay were studied as a function of firing temperature and atmosphere. From a comparison of these data with those form the sherds one can make estimates of the precolumbian firing conditions.     

Mössbauer studies of Inca ceramics

To obtain information on the firing of inca ceramics, 7 samples from different locations were studied by Mössbauer spectroscopy including a detailed laboratory refiring procedure. The glaze typical for the surface of this ware was studied by Mössbauer scattering.     

Mössbauer study of illite associated with iron oxi-hydroxides

An illite separated from mylonites from the southern rim of the Bohemian massif was studied by Mössbauer spectroscopy at temperatures between 300 and 1.8 K. The iron is mainly contained in oxides associated with the illite. Only 13% of the iron are structural Fe³⁺ and Fe²⁺ within the clay mineral matrix. The transformations of the oxidic iron during heating at temperatures up to 1250°C were followed by Mössbauer measurements at 300 and 4.2 K.     

Chemical reactions of cycloalkanespirohydantoins. Part 2. Synthesis of new 4-hydroxyimidazolidinone N3-substituted from cycloalkanespirohydantoins

N₃-Substituted hydantoins have been to undergo lithium aluminum hydride reduction (THF, room temperature, 5 hours) to give 4-hydroxy-2-imidazolidinones in good yields.     

Molecular dynamics of complex gas-phase reactive systems by time-dependent groups

A novel way of assembling the total potential for performing molecular dynamical studies of complex gas-phase reactive chemical systems is introduced. The method breaks the calculation of the total potential and gradients of the potential into time-dependent groups that are governed by spatial cutoffs. These groups evolve during the course of the simulation and their number may increase or diminish as the dynamics of the system determine. In an effort to extend the simulation time of these complex reactive processes and to use high levels of theory when necessary, multiple levels of theory may be used over the groups for the calculation of both the intragroup and intergroup interactions. Representative simulations are performed to illustrate the method and a computationally facile method of obtaining the groups of a simulation are also discussed.     

Determination of Gatifloxacin in Semen by HPLC with Diode-Array and Fluorescence Detection

The objective of this work was to develop an analytical HPLC method, using DAD and fluorescence detection, for determination of gatifloxacin in semen. A reversed-phase column was used with 90:10 water-acetonitrile, containing 10 mM TBA and 25 mM citric acid, as mobile phase. Semen was deproteinized with acetonitrile. Recovery was 95 ± 10%. The limits of quantification by DAD and fluorescence were 2.3 and 0.03 μg.mL^?1 respectively, with RSD of 3.4% for DAD and 2.8% for fluorescence. The method with fluorescence detection was used for quantification of gatifloxacin in the semen of patients under treatment.