Chemical Composition

Solid materials with a porous structure as a chitosan microparticles are very often applied where their sorption ability plays the main role. In this study, microparticles were formed by means of spray drying of two chitosan salts: acetate and ascorbate, and two cross-linking agents glutaraldehyde and sodium triphosphate were added to the solution. Dry microparticles as a product of different chemical composition had different structural characteristics: shape, size, density, and volume and area of pores. Sorption ability of these microparticles was investigated by measuring the sorption of benzene and carbon dioxide (in a highly-vacuum sorptive instrument) and water vapour. The presented results show that pore volume attains big values when glutaraldehyde is added as a cross-linking substance. But the highest sorption ability of benzene vapour is in the case of microparticles of chitosan acetate without any cross-linking substances. Results of these investigations reveal high possi...

The possibility of developing a photochemical setup on the basis of an optically pumped ammonia laser with an intracavity photoreactor is proved. The obtained values of the cavity 'implication' factor γ are comparable with those of intracavity systems based on a CO2 laser. The conditions for achieving the maximum energy in the focusing cavity are determined and the ways to control the shape of its caustic are indicated.

Road dust (RD) resuspension is one of the main sources of particulate matter in cities with adverse impacts on air quality, health, and climate. Studies on the variability of the deposited PM10 fraction of RD (RD10) have been limited in Latin America, whereby our understanding of the central factors that control this pollutant remains incomplete. In this study, forty-one RD10 samples were collected in two Andean cities (Bogotá and Manizales) and analyzed for ions, minerals, and trace elements. RD10 levels varied between 1.8–45.7 mg/m2, with an average of 11.8 mg/m2, in Bogotá and between 0.8–26.7 mg/m2, with an average of 5.7 mg/m2, in Manizales. Minerals were the most abundant species in both cities, with a fraction significantly larger in Manizales (38%) than Bogotá (9%). The difference could be explained mainly by the complex topography and the composition of soil derived from volcanic ash in Manizales. The volcanic activity was also associated with SO4⁻2 and Clˉ. Enrichment factors and principal component analysis were conducted to explore potential factors associated to sources of RD10. Elements such as Cu, Pb, Cr, Ni, V, Sb, and Mo were mainly associated with exhaust and non-exhaust traffic emissions.

Abstract— The impact melt breccias from the Tenoumer crater (consisting of a fine-grained intergrowth of plagioclase laths, pyroxene crystals, oxides, and glass) display a wide range of porosity and contain a large amount of target rock clasts.Analyses of major elements in impact melt rocks show lower contents of SiO2, Al2O3, and Na2O, and higher contents of MgO, Fe2O3, and CaO, than the felsic rocks (i.e., granites and gneisses) of the basement. In comparison with the bulk analyses of the impact melt, the glass is strongly enriched in Si-Al, whereas it is depleted both in Mg and Fe; moreover, the impact melt rocks are variably enriched or depleted in some REE with respect to the felsic and mafic bedrock types. Gold is slightly enriched in the impact melt, and Co, Cr, and Ni abundances are possibly due to a contribution from mafic bedrock.Evidences of silicate-carbonate liquid immiscibility, mainly as spherules and globules of calcite within the silicate glass, have been highlighted.HMX mixing calculation confirm that the impact melt rocks are derived from a mixing of at least six different target lithologies outcropping in the area of the crater. A large contribution is derived from granitoids (50%) and mica schist (17–19%), although amphibolites (˜15%), cherty limestones (˜10%), and ultrabasites (˜6%) components are also present.The very low abundances of PGE in the melt rock seem to come mainly from some ultrabasic target rocks; therefore, the contamination from the meteoritic projectile appears to have been negligible.

Plant herbivores often stimulate lignin deposition in injured plant tissue, but it is not known whether corn (Zea mays L.) reacts to European corn borer (ECB, Ostrinia nubilalis Hubner) injury in this manner. Bt (Bacillus thuringiensis) genetic modification is also reported to affect lignin in corn. This study evaluated the effects of ECB injury and the Bt gene on the

Fossil leaves which show excellent preservation of lipids and other organic compounds are preserved in abundance at the Miocene Clarkia lake deposit in northwestern Idaho, USA. Eighty three fossils from nine genera which are commonly found at the site, namely Quercus, Platanus, Magnolia, Pseudofagus, Fagus, Cocculus, Taxodium, Metasequoia and Sequoia were investigated to assess whether their chemical compositions can be used in chemotaxonomic comparisons. Chromatographically separated n-alkane and n-alkanol sub-fractions were examined by GC and GC/MS to establish whether characteristic distributions were evident between fossils and distinct from the enclosing sediment. Chemotaxonomic comparisons were performed between the individual fossil specimens and six sediments using the n-alkane and n-alkanol profiles and principal component analysis (PCA). Characteristic distributions were observed for certain genera, e.g. Platanus and Quercus, which were reproducible between multiple specimens of the same genus. Concentrations of the lipids in fossils were markedly greater than in the six sediments in all of the fossils except the conifers examined. These findings demonstrate that n-alkyl lipid distributions from fossil leaves have chemotaxonomic utility, with potential for comparisons with modern taxa.

Various aspects of the water economy were investigated for a range of herbaceous species varying in relative growth rate. Plants were grown in a growth chamber with a non-limiting supply of water and nutrients, and the rate of transpiration, short-term intercellular CO2 concentration and long- term carbon isotope discrimination (∆) in the leaves were determined. No correlation was found between the relative growth rate of these species, and the transpiration rate per unit leaf area, the intercellular CO2 concentration and the 13 C-discrimination. There was a positive correlation, however, with the rate of water uptake per unit root weight. From these observations we infer that the previously observed differences in photosynthetic nitrogen-use efficiency, the rate of photosynthesis per unit leaf nitrogen, can not be explained by variation in intercellular CO2 concentration. These data were also used to analyse correlations between ∆ and both growth parameters and chemical composition...