Search results for "Note"
showing 10 items of 10709 documents
Xylochemical Synthesis of Cytotoxic 2-Aminophenoxazinone-Type Natural Products Through Oxidative Cross Coupling
2019
Today, the total synthesis of natural products mostly relies on the use of petroleum-based starting materials. The commercial availability of building blocks of this type often deflects attention away from lengthy synthetic routes required for the reintroduction of heteroatom substitution patterns lost in the geological process of kerogenesis. Herein, the use of wood-based starting materials, the so-called xylochemicals, for the synthesis of 2-aminophenoxazinone natural products is presented. The inherent heteroatom substitution patterns as well as chemical functionalities were employed and permitted a short and straightforward synthetic strategy. Moreover, a novel and “green” method for co…
De novo production of six key grape aroma monoterpenes by a geraniol synthase-engineered S. cerevisiae wine strain
2015
[Background] Monoterpenes are important contributors to grape and wine aroma. Moreover, certain monoterpenes have been shown to display health benefits with antimicrobial, anti-inflammatory, anticancer or hypotensive properties amongst others. The aim of this study was to construct self-aromatizing wine yeasts to overproduce de novo these plant metabolites in wines.
Germacranolides and a monoterpene cyclic peroxide from Artemisia fragrans
1998
Abstract The aerial parts of Artemisia fragrans collected in Armenia yielded a new cyclic monoterpene peroxide with the irregular santolinyl framework, together with several known germacranolides. Comparison with previously published chemical results suggests these may actually have been performed on a different, although closely related species.
Alma Mater: 2013/ Rudens
2013
Mārcis Auziņš. Vienīgā Latvijas Universitāte - par izcilību izglītībā un zinātnē; Andra Čudare. Jānis Stradiņš un Mārcis Auziņš: kultūra zinātnē un zinātne kultūrā; Anete Enikova. Pretī akadēmiskajām zināšanām ar ielu sportu asinīs – Ghetto Games stipendiāti; LU Preses centrs. Piepūšamā kinoteātrī uzzini par klimata pārmaiņām Baltijā; Jeļena Poļakova. LU Ērģeles tapa par ziedojumiem – nu laiks tās atjaunot; Andra Čudare. Izcilnieki jeb kad 8 ir slikta atzīme; Indra Gleizde. Latvijas datorzinātniekus pazīst arī pasaulē; Laboratorijās izstrādātos skaistumkopšanas līdzekļus izmēģina brīvprātīgie; Gita Siliņa. Atmiņu pētnieku piedzīvojumi; LU Preses centrs. Iepazīs studijas no skolas brīvajā la…
Foreign Body Giant Cell–Related Encapsulation of a Synthetic Material Three Years After Augmentation
2016
Bone substitute materials of different origin and chemical compositions are frequently used in augmentation procedures to enlarge the local bone amount. However, relatively little data exist on the long-term tissue reactions. The presented case reports for the first time histological and histomorphometrical analyses of a nanocrystaline hydroxyapatite–based bone substitute material implanted in the human sinus cavity after an integration period of 3 years. The extracted biopsy was analyzed histologically and histomorphometrically with focus on the tissue reactions, vascularization, new bone formation, and the induction of a foreign body reaction. A comparably high rate of connective tissue (…
Effect of pressure and temperature on viscosity of a borosilicate glass
2018
International audience; During industrial glass production processes, the actual distribution of stress components in the glass during scribing remains, to date, poorly quantified, and thus continues to be challenging to model numerically. In this work, we experimentally quantified the effect of pressure and temperature on the viscosity of SCHOTT N-BK7 glass, by performing in situ deformation experiments at temperatures between 550 and 595 °C and confining pressures between 100 MPa and 300 MPa. Experiments were performed at constant displacement rates to produce almost constant strain rates between 9.70 × 10 −6 s-1 and 4.98 × 10-5 s-1. The resulting net axial stresses range from 81 MPa to 8…
Investigation of the Na2O/Ag2O ratio on the synthesis conditions and properties of the 80TeO2–10ZnO–[(10−x)Na2O–xAg2O] glasses
2019
International audience; Properties of the tellurite glasses 80TeO2–10ZnO–[(10−x)Na2O–xAg2O] are investigated as a function of the substitution ratio x between Na2O and Ag2O. One observe that the variation of glass transition temperature decreases monotonously with x and that surface crystallization mechanism is favored. The assignment of the Raman bands and their relation with the underlying glass structure is discussed. While both Na2O and Ag2O oxides act as glass network modifiers, their progressive equimolar substitution does not lead to a meaningful evolution in the structure of the TZ[Na10-xAgx] glass. The refractive index and the cut-off wavelength are found to increase with x. The co…
Strong Bonding of Single C60 Molecules to (1 × 2)-Pt(110): an STM/DFT Investigation.
2007
International audience; The interaction of single C60 molecules with the (1 × 2)-Pt(110) surface has been studied by scanning tunneling microscopy and density functional theory (DFT) calculations on slab models. Molecules are observed to be frozen at room temperature and are found to be almost exclusively in the same configuration. Extensive DFT calculations show that this configuration is the global energy minimum, suggesting that adsorbed molecules have enough rototranslational freedom to escape from the numerous local minima. The adsorption energy (3.81 eV) is the strongest ever found for C60, and it is roughly proportional to the number of the Pt and C atoms at contact distance. Analysi…
Plasma Etching and Integration with Nanoprocessing
2009
This chapter introduces plasma etching—an extensive and perhaps the most widely used micro- and nanoprocessing method both in industry and in research and development laboratories worldwide. The emphasis is on the practical methods in plasma etching and reactive ion etching when used for submicron and nanoscale device fabrication. The principles of plasma etching and reactive ion etching equipment for sample fabrication will be introduced.
Microwave-assisted catalytic esterification of α-glucoisosaccharino-1,4-lactone with tall oil fatty acids
2016
Background: Carbohydrates-rich materials are partly degraded during alkaline kraft pulping into a complex mixture of aliphatic carboxylic acids consisting of α-glucoisosaccharinic acid as one of the main acids. On the other hand, crude tall oil, containing significant amounts fatty acids, is obtained as a by-product from kraft pulping. One interesting novel approach is to utilize chemically both these side-streams by producing renewable surfactants from aliphatic carboxylic acids and fatty acids via esterification. Results: In this paper, lauric (C12:0) and oleic (C18:1) acids as well as a mixture of tall oil fatty acids were esterified with α-glucoisosaccharino-1,4-lactone in a microwave-a…