Search results for "urea"
showing 10 items of 888 documents
Dithiametacyclophane mit Dreifachbindungen
1994
Dithiametacyclophanes with Triple Bonds Schemes 1 and 2 show the syntheses of dithia[8]metacyclo-phanes 4a-d and tetrathia[m.n]metacyclophanes 9, 10 by cyclization reactions applying the cesium effect. All these cyclophanes contain C—C triple bonds which influence the molecular dynamics; especially the halogen substituents in 4b-d obstruct the topomerization.
Role of the thermal treatment on the microstructure of YAGG nanopowders prepared by urea glass route
2023
Yttrium aluminium gallium garnet (YAGG, Y3Al2Ga3O12) doped with rare-earth ions has drawn large attention owing to its optical properties with applications ranging from persistent luminescent phosphors to nanothermometers. Herein, three different YAGG materials were synthesized via the urea glass route followed by thermal treatment, relatively undoped; doped with Ce3+, Cr3+, and Nd3+; and doped with Ce3+, Cr3+, and Yb3+. The garnet formation was studied in situ upon thermal treatment from 300 to 1000 ◦C using synchrotron powder diffraction. Our results show that with this method, the onset of formation of the garnet is about 860 ◦C, with comparable cell parameters for both undoped and doped…
Study of AOT-stabilized microemulsions of urea dispersed in carbon tetrachloride
2003
Measurements of some physico-chemical properties (density, viscosity, permittivity) of the urea/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/CCl4 system as a function of the volume fraction of the dispersed phase (0<Φ<0.7) at various urea to AOT molar ratio (Rurea) have been carried out at 25 °C. The experimental data analysis are consistent with the hypothesis that urea is entrapped as small-size molecular clusters within the hydrophilic core of the AOT reversed micelles and that this structure is preserved well above a threshold Φ value where a percolative transition occurs. Besides, X-ray diffraction spectra of samples at Φ=1, obtained by complete evaporation under vacuum of the apolar …
Tetraurea calix[4]arenes with sulfur functions: synthesis, dimerization to capsules, and self-assembly on gold.
2007
Various calix[4]arene derivatives, fixed in the cone conformation by decylether groups and functionalized at their wide rim by urea residues, were synthesized. In two compounds (4f,g) sulfur functions were attached to the urea groups via different spacers in order to allow binding to metal surfaces. While they exist as single molecules in polar solvents, tetraurea calix[4]arenes of this type (4) combine to form dimeric capsules in aprotic, apolar solvents. A solvent molecule is usually included in such a capsule, if no guest with a higher affinity is present. In the presence of an equimolar amount of the tetratosylurea 5, the exclusive formation of heterodimers, consisting of one molecule o…
Decongestion discriminates risk for one-year mortality in patients with improving renal function in acute heart failure
2021
Aims Improving renal function (IRF) is paradoxically associated with worse outcomes in acute heart failure (AHF), but outcomes may differ based on response to decongestion. We explored if the relationship of IRF with mortality in hospitalized AHF patients differs based on successful decongestion.Methods and results We evaluated 760 AHF patients from AKINESIS for the relationship between IRF, change in B-type natriuretic peptide (BNP), and 1-year mortality. IRF was defined as a >= 20% increase in estimated glomerular filtration rate (eGFR) relative to admission. Adequate decongestion was defined as a >= 40% decrease in last measured BNP relative to admission. IRF occurred in 22% of pat…
Determination of urea-derived pesticides in fruits and vegetables by solid-phase preconcentration and capillary electrophoresis
2001
A multiresidue analytical method based on solid-phase extraction (SPE) enrichment combined with capillary electrophoresis (CE), using micellar electrokinetic capillary chromatography (MEKC), was developed to determine ten substituted urea pesticides in orange and tomato samples. Several factors such as pH, composition and concentration of the buffer, concentration of surfactant, addition of organic solvent, and working voltage were optimized to obtain the best compound separation in the shortest time. Separation can be achieved in 7 min using a micellar aqueous pH 9 buffer composed of 4 mM borate and 35 mM sodium dodecyl sulfate. After an SPE procedure, which provided a 10-fold enrichment, …
A study on Norwegian companies in China: Challenges & successful strategies
2016
Master thesis Business Administration BE501 - University of Agder 2016 This paper examines what governmental and cultural challenges Norwegian companies face when entering and doing business in China. In addition, this paper also discusses what strategies to implement to overcome these challenges. With China becoming a bigger player in the global marketplace, this is an important matter not only for companies across the world but also for Norwegian companies. Through a qualitative research method with semi-structured interviews, the research is conducted on four Norwegian companies who does business in China. The findings shows that there are many variables affecting the choice of entry mod…
Understanding idioms : a comparison of Finnish third grade students of national senior secondary school and IB Diploma Programme
2006
European administrative centre formation. Lessons from international bureaucracies
2011
The strengthening of administrative powers is comprehensively documented within national governments. This article asks to what extent centre formation also happens within international bureaucracies. Based on a large body of data (N=121) within three international bureaucracies, this study adds two new observations: First, administrative centre formation is primarily observed inside the European Commission and only marginally within other international bureaucracies – such as the OECD and WTO Secretariats. Moreover, within the Commission, centre formation is primarily observed at the administrative centre (the General Secretariat) and only marginally within bureaucratic sub-units. Concomit…
Flow-cytometric screening for the modulation of receptor-mediated endocytosis in human dendritic cells: implications for the development of an in vit…
1997
The aim of this study was to explore the usefulness of human blood dendritic cells (DC) in the development of an in vitro model for predictive testing of contact sensitizers. A method was established to monitor the influence of chemicals on the intracellular targeting of antibody-crosslinked MHC class II molecules after their uptake by human DC. Using a three-colour flow-cytometric technique, freshly prepared DC were distinguished from other MHC class II-bearing cell types such as B-cells and monocytes in unseparated mononuclear cell suspensions of healthy volunteers. The assay is based on the pH-sensitivity of internalized fluorescein-coupled MHC class II specific antibodies. Quenching of …