Separation and identification of volatile components in the fermentation broth of Trichoderma atroviride by solid-phase extraction and gas chromatography-mass spectrometry

A preseparated fermentation broth of Trichoderma atroviride strain 11 is analyzed by gas chromatography followed by mass-spectral detection using a Finnigan MAT GCQ apparatus. After preseparation in a C18 and a silica gel column, nineteen pyrone and dioxolane derivatives and two aliphatic esters are obtained, respectively. Among these, the four dioxolane derivatives have not been identified previously. The main component is found to be 5,5'-dimethyl-2H-pyran-2-on. The relative standard deviation for the determination of the retention time and the peak area (measured in ion counts) is 0.1% and 4.5%, respectively.     

Quantitative analysis of subdiffractive light propagation in photonic crystals

We present a qualitative study of the subdiffractive light beam propagation in photonic crystals, based on the theoretical analysis of full Maxwell equation system beyond the slowly varying envelope and paraxial approximations. We calculate the zero diffraction curve in the parameter space, we calculate the weak asymptotical broadening (spreading in transverse direction), and we also analyze the dependence of subdiffractive propagation on the polarization orientation (both for TM and TE polarization).     

Frontal polymerizations carried out in Deep-Eutectic mixtures providing both the monomers and the polymerization medium

Deep Eutectic Solvents (DESs) based upon mixtures of Acrylic Acid (AA) or Methacrylic Acid (MAA) and Choline Chloride (CCl) demonstrated superior performance than regular organic solvents and even ionic liquids for frontal polymerizations (FPs). Full recovering of CCl after FP provided an interesting green character to the process.     

Ab initio and DFT conformational study on nitrosamine (H<Subscript>2</Subscript>N–N=O) and <Emphasis Type="Italic">N</Emphasis>-Nitrosodimethylamine [(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>N–N=O]

Abstract  

Ab initio and DFT calculations have been performed to characterize some ground state structures of the title molecules. Relative energies, rotational barriers, NBO charges, and dipole moments (μ) have been calculated and analyzed. It has been confirmed that only highly correlated methods (e.g., CCSD) are able to yield the non-planar structure as a minimum, for the H₂NNO molecule. On the other hand, all computational levels here employed are able to yield a planar C₂NNO frame for the (CH₃)₂NNO as a minimum. Important correlations between atomic charges and bond distances are discussed. Replacement of H by methyl group increases the rotational barrier and μ values by at least 3 kcal/mol and 0.4 D, respectively. The largest μ values are obtained for the structures in which the nitrogen lone pair is parallel to the NO group π system, and are consistent with a larger contribution of a dipolar resonance structure.     

Micro‐Raman spectroscopy and SEM/EDX applied to improve the zircon fission track method used for dating geological formations

The zircon mineral is widely studied in geochronology. In the case of the fission track method (FTM), the age is determined by the density of fission tracks at the zircon surface, which can be observed with an optical microscope after an appropriate chemical treatment (etching). The etching must be isotropic at the zircon grain surface to be used in the FTM, which leads those zircon grains whose etching is anisotropic to be discarded. The only reason for this discarding is the nonuniform morphology of the surface grain seen by optical microscopy, that is, no further physicochemical analysis is performed. In this work, combining micro‐Raman and scanning electron microscopy (SEM) to study the etching anisotropy, it was shown that zircon grains that present at least one area at the surface where the density of fission track is uniform can be used in the FTM. The micro‐Raman showed characteristic spectra of the standard zircon sample either from the areas where there are tracks or from where there are not. The only difference found was in the Raman bandwidths, which were broader for the areas with higher density of fission tracks. This suggests simply a decrease in the relative percentage of the crystalline/amorphous phases at these areas. The SEM/energy dispersive spectrometry (EDX) showed that there were no significant differences in the principal chemical composition at the areas with and without fission tracks. Copyright © 2008 John Wiley & Sons, Ltd.