Search results for "Phase"
showing 10 items of 6344 documents
Partial Discharge Tests Using CIGRE Method II Upon Nanocomposite Epoxy Resins
2007
Nanocomposite polymers are becoming a new family of dielectric materials with promising insulating properties. In order to apply this technology to insulation systems, a study about the material longterm endurance (life) is needed. In this paper results from comparative life tests performed upon base and nanostructured epoxy resin samples are presented. The nanofiller is a organophillic-modified ultra-clean montmorillonite. Specimens were subjected to ageing under surface discharge phenomena using a standard electrode configuration, that is the CIGRE method II. Life data and partial discharge phase resolved patterns, acquired during time under stress, are presented and commented, in order t…
Selective localization of organoclay and effects on the morphology and mechanical properties of LDPE/PA11 blends with distributed and co-continuous m…
2010
A study was made on the effect of small amounts of organically modified clay on the morphology and mechanical properties of blends of low-density polyethylene and polyamide 11 at different compositions. The influence of the filler on the blend morphology was investigated using wide angle X-ray diffractometry, scanning and transmission electron microscopy and selective extraction experiments. The filler was found to locate predominantly in the more hydrophilic polyamide phase. Although such uneven distribution does not have a significant effect on the onset of phase co-continuity of the polymer components, it brings about a drastic refinement of the microstructure for the blends both with dr…
Experimental Studies for Modelling the Phase Behaviour of Monomer/Polymer/Disc Composites
2010
Nanoparticles do not stabilize the mixtures of epoxy monomer (prepolymer)/thermoplastic modifier (PS) and the ones of thermoplastic modifier dispersed within cured epoxy matrix. A small amount of thermoplastic co-polymer poly(styrene-b-methyl methacrylate) [P(S-b-MMA)] of MMA 4-22 wt.%, mixed with PS, makes compatible the mixtures with monomer epoxy precursor and cured epoxy matrix. The mixtures of cured epoxy matrix with thermoplastic consisting of PS and P(S-b-MMA), with nanofil 1%, are stable: the instability produced by the nanofil is overcome by the stability provided by the co-polymer. A model by Balazs' group to explain the phase behaviour of polymer/clay composites is extended.
Phase transitions in polymeric systems: A challenge for Monte Carlo simulation
1995
Polymers are more difficult to simulate than small molecule systems, due to the large size of random polymer coils (and their slow relaxation, that is observed when dynamic simulation algorithms are used). However, variation of the chain length N of a flexible polymer chain provides a very useful additional control parameter, allowing stringent tests of theories, and new physical phenomena may emerge. As an example of these concepts, critical phenomena in polymer mixtures are described. It is shown that unmixing of symmetrical mixtures ( N A = N B = N ) is described by an equation for the critical temperature T c ( N ) = aN + b rather than T c ∝ N as claimed by some theories. While for fini…
Synthetic Tumor-Associated Glycopeptide Antigens from the Tandem Repeat Sequence of the Epithelial Mucin MUC4
2004
In cancer research, the development of vaccines against tumor-associated antigens is of particular interest. Epithelial cells express mucin type glycoproteins, which are extensively O-glycosylated. In case of cancer, the expression of these mucins is increased, and their carbohydrate side chains show an aberrant glycosylation pattern. A set of single and double glycosylated hexadecapeptides representing the tandem repeat sequence of the epithelial mucin MUC4 carrying different tumor-associated carbohydrate antigens was prepared by sequential solid-phase glycopeptide synthesis. The crucial glycosyl amino acid building blocks containing the T N , T, sialyl-T N and (2,6)-sialyl-T antigens were…
The Efficiency of Polymer Fractionation at Lower Critical Solution Temperatures
1978
The efficiency of a single fractionation step (i.e. of the partition of a given polymer sample between the coexisting phases which form when its solution demixes) is governed by the variation of the mass ratio of the individual P-mers with chain length. These dependences have been measured for the system dimethoxymethane/diethylether/ polystyrene which exhibits lower critical solution temperatures by means of the Baker-Williams method and by means of g.p.c. Their comparison with the results of previous investigation on systems showing upper critical solution temperatures reveals no thermodynamic differences in the aptitude of upper and lower critical solution temperatures for fractionation …
Calculation of the Phase Behavior of Lipids
1998
The self-assembly of monoacyl lipids in solution is studied employing a model in which the lipid's hydrocarbon tail is described within the Rotational Isomeric State framework and is attached to a simple hydrophilic head. Mean-field theory is employed, and the necessary partition function of a single lipid is obtained via a partial enumeration over a large sample of molecular conformations. The influence of the lipid architecture on the transition between the lamellar and inverted-hexagonal phases is calculated, and qualitative agreement with experiment is found.
Feature characterization of scarring and non-scarring types of alopecia by multiphoton microscopy (Conference Presentation)
2018
Treatment and management of alopecia are highly determined by an accurate diagnosis, which can be challenging due to the lack of methods to properly visualize hair follicles. Current standard diagnosis is based on dermoscopy for non-scarring alopecia and scalp biopsy for scarring types of alopecia. Dermoscopy can be inconclusive, while biopsy is a painful procedure. In this study, we used a clinical tomograph based on multiphoton microscopy (MPM) to non-invasively image the scalp of 5 healthy subjects and of 12 patients affected by non-scarring alopecia (androgenetic and areata) and scarring alopecia (frontal fibrosing). MPM is capable of non-invasive in vivo imaging of follicular structure…
Super-high-speed liquid chromatography of proteins and peptides on non-porous Micra NPS-RP packings
1999
Abstract The new generation of non-porous silica RP packings commercially available from Micra Scientific was tested for separations of peptides and proteins by means of the gradient HPLC. Extremely high-speed separations were achieved using conventional chromatographic equipment: six proteins could be completely separated within six seconds. Tryptic digest peptides could be resolved in more then 40 components within 2–3 min. The effect of the experimental parameters such as temperature, flow rate etc. was investigated.
Combinatorial synthesis of amino acid- and peptide-carbohydrate conjugates on solid phase
2004
Carbohydrates are useful polyfunctional scaffold molecules which allow the selective attachment of a number of different side chains. The combinatorial solid phase synthesis of diverse amino acid or peptide conjugates of a polyfunctional glucose scaffold based on a set of selectively removable and orthogonally stable protecting groups is described. The resulting carbohydrate-peptide hybrids constitute potential turn mimetics.