Search results for "Cyanate"
showing 10 items of 210 documents
Changes in Gastric Mucosal Permeability Induced by Haemorrhagic Shock in the Anaesthetized Rat: - Modulation by Acid
1998
Abstract Gastric mucosal damage induced by haemorrhagic shock in the anaesthetized rat has been evaluated by studying changes in capillary-to-lumen clearance of fluorescein isothiocyanate (FITC)-labelled dextran. Haemorrhagic shock (20 min ischaemia + 20 min reperfusion) induced a significant increase in blood-to-lumen permeability to FITC-dextran of different molecular weight (10 000, 40 000 and 70 000) without modifying the macroscopic integrity of the gastric mucosa. The increase in vascular permeability was dependent on the time of administration of the tracer and was correlated with an elevation of the protein content of the gastric lumen. Intravenous administration of the secretagogue…
Comparative histological, histochemical, immunohistochemical and biochemical studies on oestrogen receptors, lectin receptors, and Barr bodies in hum…
1986
The present study performed on a total of 567 cases of human female breast cancer compares the results of the biochemical assay (dextran-coated charcoal assay = DCC) for oestrogen receptor (ER) with those of several morphological methods developed for the detection of the ER or for the prediction of prognosis by use of other systems (FSA = fluorescent ligand binding assay, ER-ICA = monoclonal antibody assay for ER, LRA = lectin receptor assay using peanut agglutinin, and Barr body estimation). Whereas no correlation at all was observed among the results of the DCC and those of the FSA and Barr body estimation, the ER-ICA and the LRA showed an unanimous tendency towards higher values of ER w…
Blood volume and extracellular space (ECS) of the whole body and some organs of the rat.
1978
Methods are described for estimation of blood volume and extracellular space (ECS) in the whole body and in some organs with 51Cr, 14C-thiocyanate and 3H-inulin. A mean blood volume of 47 ml/kg, a thiocyanate space of 350 ml/kg and a inulin space of 288 ml/kg were determined in the rat. The corresponding values of organs are shown in figures 1--3.
Controlled Synthesis of Multi-Arm Star Polyether-Polycarbonate Polyols Based on Propylene Oxide and CO2
2013
Multi-arm star copolymers based on a hyperbranched poly(propylene oxide) polyether-polyol (hbPPO) as a core and poly(propylene carbonate) (PPC) arms are synthesized in two steps from propylene oxide (PO), a small amount of glycidol and CO2 . The PPC arms are prepared via carbon dioxide (CO2 )/PO copolymerization, using hbPPO as a multifunctional macroinitiator and the (R,R)-(salcy)CoOBzF5 catalyst. Star copolymers with 14 and 28 PPC arms, respectively, and controlled molecular weights in the range of 2700-8800 g mol(-1) are prepared (Mw /Mn = 1.23-1.61). Thermal analysis reveals lowered glass transition temperatures in the range of -8 to 10 °C for the PPC star polymers compared with linear …
Lineare polyester mit alkoholischen endgruppen und deren bestimmung
1955
Lineare Bernsteinsaure-1,6-Hexandiol-Polyester mit alkoholischen Endgruppen werden mit einem uberschus des Diols durch Schmelz- und durch Losungskondensation hergestellt. Hohermolekulare Polyester mit uberwiegend alkoholischen Endgruppen werden durch. Nachkondensation mit dem Diol erhalten. Die Umsetzung der Produkte mit Phenylisocyanat fuhrt zu Polyesterdiurethanen. Die Ermittlung des Stickstoffs nach Kjeldahl liefert mit befriedigender Genauigkeit Endgruppenmolekulargewichte bis zum Molgewicht ∼5 · 103. Bei der Totalhydrolyse der Polyesterdiurethane bildet sich Anilin, das mit einem empfindlichen, photometrischen Verfahren quantitative erfast wird. Aus der so bestimmten Anilinmenge wurden…
FTIR isothermal cure kinetics and morphology of dicyanate ester resin/polysulfone blends
2005
Abstract The isothermal cure of a dicyanate ester monomer by “in situ” Fourier transform infrared spectroscopy (FTIR) has been investigated. The degree of cyanate conversion and the kinetic parameters have been determined for cobalt catalyzed and uncatalyzed resin as well as for polysulfone (PSF) modified systems at different curing temperatures. The cyanate conversion increases with the increment of temperature and with the addition of a catalyst, but it does not vary with the addition of PSF. In all the systems studied, the rate of reaction showed a second-order dependence on the cyanate concentration in the kinetically controlled stage. Moreover, the addition of PSF generates a matrix wi…
Kinetic parameters of a cyanate ester resin catalyzed with different proportions of nonylphenol and cobalt acetylacetonate catalyst
2005
The isothermal cure of a dicyanate ester monomer has been investigated by differential scanning calorimetry (DSC) in the presence of different quantities of a catalyst system formed by nonylphenol (NP) and cobalt (II) acetylacetonate (Co(AcAc)2). Two sets of experiences were studied. Firstly, the NP composition was varied from 0 to 10 per hundred resin (phr) and secondly, the Co(AcAc)2 loadings were changed at 2 phr of NP. It has been observed that the cyanate conversion increases significantly after the first addition of the metal catalyst and, also, at the same time the thermal stability improves. Moreover, the kinetic data have been fitted with a second-order equation respect to the cyan…
Cure monitoring of catalysed cyanate ester resins
2000
The cure behaviour of two bisphenol A-based cyanate ester resins, AroCy B10 and B30, catalysed by copper acetylacetonate and nonylphenol was studied. For this purpose, differential scanning calorimetric (DSC) and rheological measurements were carried out at temperatures between 130 and 170 °C. The cyanate conversion profiles are fitted with a second-order rate law in the kinetically controlled regime where a good time–temperature superposition is attained. However, it is necessary to add an empirical kinetic term to give a good description of the entire range of curing. Simultaneously, times to gelation and vitrification have been determined by dynamic rheological measurements over the same…
Investigation of compatibility of a dicyanate ester monomer and polysulfone by size-exclusion chromatography and viscometry
2003
The influence of solvent on the compatibility behaviour of Arocy B10, a cyanate ester monomer, and polysulfone (PSF) was investigated by means of dilute solution viscometry and of the preferential solvation parameter at 25 °C. The ternary systems under study are: tetrahydrofuran/Arocy B10/polysulfone (PSF), N,N-dimethylformamide/Arocy B10/PSF and dichloromethane/Arocy B10/PSF. Values of the specific viscosity of PSF in a ‘binary solvent’ formed by Arocy B10 + solvent have been used to determine the compatibility of the polymer blend Arocy B10/PSF. An interaction parameter Δb that depends on concentration has been determined. The preferential solvation parameter was measured by size-exclusio…
Reactive Self-Assembly and Specific Cellular Delivery of NCO-sP(EO-stat-PO)-Derived Nanogels
2018
This study presents the reactive self-assembly of isocyanate functional and amphiphilic six-arm, star-shaped polyether prepolymers in water into nanogels. Intrinsic molecular amphiphilicity, mainly driven by the isophorone moiety at the distal endings of the star-shaped molecules, allows for the preparation of spherical particles with an adjustable size of 100-200 nm by self-assembly and subsequent covalent cross-linking without the need for organic solvents or surfactants. Covalent attachment of a fluorescence dye and either the cell-penetrating TAT peptide or a random control peptide sequence shows that only TAT-labeled nanogels are internalized by HeLa cells. The nanogels thus specifical…