Search results for "Molar"
showing 10 items of 1069 documents
Chain-extending of Hydroxytelechelic Polybutadiene: Synthesis and Characterization
2010
Extension of hydroxytelechelic polybutadiene oligomers ( 3200 g/mol) is performed in mild conditions, in order to avoid backbone modifications, using succinic anhydride or methylenedicyclohexyl diisocyanate. The two routes present significative extension of the initial oligomers. Extension through the anhydride route, in the presence of DCC and DMAP, leads to new hydroxytelechelic oligomers ( 8000 g/mol). Extension through the diisocyanate route, catalyzed by DBTL at 65°C leads to hydroxytelechelic oligomers of higher average molecular weight ( 20000 g/mol). New materials are characterized by FTIR/1H-NMR and changes in their Tg according to , are discussed. The influence of reaction time on…
Radikalpolymerisation von methylmethacrylat im gesamten umsatzbereich. Stationäre und instationäre experimente zur bestimmung von wachstums- und abbr…
1989
Free-radical polymerization of methyl methacrylate in bulk at 0°C over the full range of conversion is reported. Details for stationary and non-stationary experiments are described allowing to measure both kinetically relevant ratios fk/ka and kw/ka, f representing radical efficiency, kw rate constants of propagation and ka rate constant of termination. From these ratios the absolute rate constants kw and ka are available. The photochemical decay of the initiator 1,1′-azodicyclohexanenitrile in connection with the rotating-sector technique and observation of the post-effect after stopping the initiator decay were used. The rate of polymerization and the number- and weight-average molar mass…
Meridional gradients of light absorbing carbon over northern Europe
2008
In situ measurements have been made in the upper troposphere of the properties of particles containing light absorbing carbon (LAC). These measurements, made in late November 2006 over northern Europe, show that the average LAC mass concentration varies between 1 and 5 ng m−3 over a latitude range 50° to 70°N, with maxima at 50° and 66°. The relative fraction of all particles larger than 0.1 µm that contain LAC decreases at higher latitudes. The derived extinction coefficient, which also increases with latitude, reaches a maximum of 1.4 Mm−1 at 66°. The air mass histories associated with the LAC were evaluated with back trajectory analysis using wind field analysis from the European Center …
Potential of human serum albumin as chiral selector of basic drugs in affinity electrokinetic chromatography-partial filling technique
2006
The enantiomeric resolution of compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer (BGE), protein, and compound solutions), and plug length. In this paper, the possibility of using HSA as chiral selector for enantioseparation of 28 basic drugs using this methodology is studied. The effect of the physicochemical parameters, the structural properties of compounds, and compound-HSA protein binding percentages over their chiral resolution with HSA is outlined. Based on the results obtained, a decision tree is proposed…
Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT.
2017
The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 (19.5%), 2-2-1/1 (14.6%) and 2-1-1/1 (13.0%). A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and …
Analysis of radiologic factors in determining premolar root canal systems
2000
Abstract Objectives. Certain tooth groups pose problems as to radiologic determination of root canal morphology. For example, the premolars may have superimposed roots that give the appearance of a single canal when 2 are actually present. This study examined the effect of X-ray tube inclination so as to visualize the complete root canal system in premolars. Study Design. One hundred extracted premolars were divided into 4 groups of 25 teeth each: 1MxP (first maxillary premolar), 2MxP (second maxillary premolar), 1MdP (first mandibular premolar), and 2MdP (second mandibular premolar). A total of 10 radiographs were made of each tooth in the horizontal and vertical planes (horizontal angles …
Regulation of the hDlg/hScrib/Hugl-1 tumour suppressor complex.
2008
The proper function of the Scribble tumour suppressor complex is dependent upon the correct localisation of its components. Previously we observed dynamic relocalisation of the hDlg component under conditions of osmotic stress. We now show that the other two components of the complex, hScrib and Hugl-1 display similar patterns of expression. We demonstrate, by shRNA ablation of hScrib expression, that hDlg and Hugl-1 are in part dependent upon hScrib for their correct localization. However under conditions of osmotic stress this apparent dependency no longer exists: hDlg and Hugl-1 localise to cell membranes independently of hScrib. We also demonstrate an interaction between the three compo…
Lateral reorganization of plasma membrane is involved in the yeast resistance to severe dehydration
2010
International audience; In this study, we investigated the kinetic and the magnitude of dehydrations on yeast plasma membrane (PM) modifications because this parameter is crucial to cell survival. Functional (permeability) and structural (morphology, ultrastructure, and distribution of the protein Sur7-GFP contained in sterol-rich membrane microdomains) PM modifications were investigated by confocal and electron microscopy after progressive (non-lethal) and rapid (lethal) hyperosmotic perturbations. Rapid cell dehydration induced the formation of many PM invaginations followed by membrane internalization of low sterol content PM regions with time. Permeabilization of the plasma membrane occ…
Effectivity comparison between three different enamel remineralizing agent postfix orthodontic treatment
2019
Background This study aims to compare the effectiveness of topical fluoride application, a toothpaste containing synthetic hydroxyapatite with one containing calcium sodium phosphosilicate (CSPS) in remineralizing enamel after the debonding process. Material and methods The study constituted experimental laboratory research incorporating posttest-only control group design. A metal bracket was placed on the buccal surface of 40 premolar teeth and immersed in artificial saliva. After 1 month, the bracket was debonded. The teeth were then randomly divided into four groups, namely (n = 6) the control group (C), the 1st treatment group (T1), the 2nd treatment group (T2), and the 3rd treatment gr…
In vitro validation of biomedical polyester-based scaffolds: Poly(lactide-co-glycolide) as model-case
2018
[EN] Monitoring and understanding the in vitro behaviour of polyester based scaffolds both comprising the study of the hydrolytic degradation and the cell seeding viability is essential to ensure the desired functionality, according to a given biomedical purpose. As a model case to compare the performance of techniques to monitor the in vitro behaviour, poly(lactide-co-glycolide) (PLGA) scaffolds were chosen. The in vitro hydrolytic degradation of PLGA scaffolds was carried out in water and phosphate buffered saline (PBS). The evolution of the mass loss, the molar mass, the thermal properties and the surface morphology were monitored. The hydrolytic degradation media was correspondingly eva…