Search results for "PAPER"
showing 10 items of 2166 documents
Highly selective generation of vanillin by anodic degradation of lignin: a combined approach of electrochemistry and product isolation by adsorption
2015
The oxidative degradation of lignin into a variety of valuable products has been under investigation since the first half of the last century. Especially, the chance to claim this cheap, abundant and renewable source for the production of the important aroma chemical vanillin (1) was one of the major driving forces of lignin research. So far most of the developed methods fail in technical application since no viable concept for work-up is included. This work represents a combined approach of electrochemical conversion of Kraft lignin and product recovery by adsorption on a strongly basic anion exchange resin. Electrolysis conditions are optimized regarding reaction temperatures below 100 °C…
The nature of inter- and intramolecular interactions in F2OXe…HX (X= F, Cl, Br, I) complexes
2015
Electronic structure of the XeOF2 molecule and its two complexes with HX (X= F, Cl, Br, I) molecules have been studied in the gas phase using quantum chemical topology methods: topological analysis of electron localization function (ELF), electron density, ρ(r), reduced gradient of electron density |RDG(r)| in real space, and symmetry adapted perturbation theory (SAPT) in the Hilbert space. The wave function has been approximated by the MP2 and DFT methods, using APF-D, B3LYP, M062X, and B2PLYP functionals, with the dispersion correction as proposed by Grimme (GD3). For the Xe-F and Xe=O bonds in the isolated XeOF2 molecule, the bonding ELF-localization basins have not been observed. Accord…
Similarities and differences between crystal and enzyme environmental effects on the electron density of drug molecules
2021
Abstract The crystal interaction density is generally assumed to be a suitable measure of the polarization of a low‐molecular weight ligand inside an enzyme, but this approximation has seldomly been tested and has never been quantified before. In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution, and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density. Less than 0.1 e are shifted between these two environments in total. Howeve…
Experimental and theoretical insights in the alkene-arene intramolecular π-stacking interaction
2016
Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl-vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence of equilibriums of at least four different conformations: π-stacked and face-to-edge, each of them in an s-cis/s-trans conformation. The results show that the stabilization produced by the π-π interaction makes the π-stacked conformation predominant in solution and this stabilization is slightly affected by the electron density of the aromatic counterpart. Fil: Corne, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológi…
A new neuraminic acid derivative and three types of glycopeptides isolated from the Cuvierian tubules of the sea cucumber Holothuria forskali
1973
The Cuvierian tubules of Holothuria forskali Della Chiaje, a sea cucumber found in the Adriatic Sea, were investigated with regard to their carbohydrate moieties. From a Pronase digest of these tubules three types of carbohydrate units were isolated and characterized. 1. A high-molecular-weight glycopeptide fraction was shown to contain sulphated polyfucose, galactosamine, a uronic acid and a previously unknown neuraminic acid derivative. The sulphate was shown by i.r. analysis to be present as an O-ester. The carbohydrate unit was linked O-glycosidically to threonine and serine residues in the polypeptide chain. The hitherto unknown neuraminic acid derivative (Hf-neuraminic acid) was resis…
COMPOSITION OF REFUSE DERIVED FUELS IN LATVIA AND ESTONIA IN COMPARISION WITH WORLDWIDE AVERAGE VALUES
2019
Information about composition of RDF worldwide was collected using literature analysis. RDF samples produced in Latvia and Estonia were collected, those fractional and elemental composition analyzed using standard methods. Comparing obtained results with worldwide data we have found that the quality of local RDFs in general is higher than typical values, while elevated content of chlorine must be mentioned as a problem. Results also show that majority of chlorine in studied samples exists in organic form. Recommendations to overcome this problem have been developed.
Obstáculos à produtividade científica de professoras universitárias da área de Ciências da Saúde
2013
To discover the features associated with personal and professional lives of university teachers, in the area of health sciences in the “Comunidad Valenciana” for the period 2003-2007, to learn if they contribute to a greater or lesser scientific productivity. Were interviewed in depth 30 teachers aged between 30 and 60 years in order to identify factors that hamper productivity. Have more difficulties to publish scientific papers, teachers less productive. Represent obstacles: the labor problems, the difficulty to obtain science projects and to publish in certain journals, to balance teaching and research, care work in hospitals, the maternity and children. Although the two groups of large …
Histopathological and immunohistochemical aspects of bone tissue in aseptic necrosis of the femoral head
2021
Femoral head osteonecrosis, also known as avascular necrosis, is a disease with a multifactorial etiology, characterized by a profound change of bone architecture, which leads to the diminishing of bone resistance and femoral head collapse. The main causes that lead to femoral head necrosis are represented by the decrease of local blood perfusion and increase of intraosseous pressure, because of an excessive development of adipose tissue in the areolas of the trabecular bone tissue in the femoral head. The histopathological and immunohistochemical (IHC) study performed by us showed that most of bone trabeculae were damaged by necrotic-involutive processes, their sizes being reduced, both re…
Emerging Market Contagion Under Geopolitical Uncertainty
2019
We find that 10 emerging stock markets have high risk of contagion on the regional level but lower spillover with respect to the global markets, implying a potential for diversification benefits between emerging and global markets. Regional market integration seems to have been caused by trade integration, which has a policy implication for trade agreements’ systemic risk effects. We find that the geopolitical risk has no impact on either the return, or volatility spillovers. However, the general stock market risk (VIX) is connected to individual market volatilities, while the oil market is largely receiving the spillovers from the other markets. peerReviewed
On the discursive construction of a socially responsible organization
2009
Summary Drawing upon critical discourse analysis, this article investigates how a newspaper organization is discursively legitimized as a socially responsible organization. The empirical data are based on 16 interviews conducted among the employees of a newspaper organization. The study has two main implications. First, I suggest that corporate social responsibility in a newspaper organization is constructed around a discursive struggle concerning the role and goals of the newspaper business. More importantly, such debate includes a discursive struggle between professional, social and economic claims. This study further contributes to the literature concerning discursive legitimation strate…