Search results for "Polyethylene Terephthalates"
showing 10 items of 15 documents
Long-term results of the use of silicone sheets after diskectomy in the temporomandibular joint: clinical, radiographic and histopathologic findings
1999
The aim of the present study was to evaluate the long-term results of a group of patients who had the disk of the temporomandibular joint (TMJ) removed and permanently replaced by a silicone sheet. The study group comprised 48 patients, treated in the period from 1983 to 1993. In eight patients, the implants had to be removed after an average interval of 5.6 years and they were submitted for histopathological examination. Twenty-five of the 40 patients with silastic implants in place, and five of the 8 patients who had their implants removed, were available for long-term follow-up (mean interval of 7.0 years, SD 2.8 years). Clinical function was rated according to the Helkimo Dysfunction In…
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
2010
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…
Chemical compounds and toxicological assessments of drinking water stored in polyethylene terephthalate (PET) bottles: A source of controversy review…
2012
A declaration of conformity according to European regulation No. 10/2011 is required to ensure the safety of plastic materials in contact with foodstuffs. This regulation established a positive list of substances that are authorized for use in plastic materials. Some compounds are subject to restrictions and/or specifications according to their toxicological data. Despite this, the analysis of PET reveals some non-intentionally added substances (NIAS) produced by authorized initial reactants and additives. Genotoxic and estrogenic activities in PET-bottled water have been reported. Chemical mixtures in bottled water have been suggested as the source of these toxicological effects. Furthermo…
The role of crystalline, mobile amorphous and rigid amorphous fractions in the performance of recycled poly (ethylene terephthalate) (PET)
2012
[EN] The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation of -OH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percen…
Endothelialization and Anticoagulation Potential of Surface-Modified PET Intended for Vascular Applications.
2018
In vascular tissue engineering, great attention is paid to the immobilization of biomolecules onto synthetic grafts to increase bio- and hemocompatibility-two critical milestones in the field. The surface modification field of poly(ethylene terephthalate) (PET), a well-known vascular-graft material, is matured and oversaturated. Nevertheless, most developed methods are laborious multistep procedures generally accompanied by coating instability or toxicity issues. Herein, a straightforward surface modification procedure is presented engineered to simultaneously promote surface endothelialization and anticoagulation properties via the covalent immobilization of gelatin through a photoactivate…
Ionic Transport through Chemically Functionalized Hydrogen Peroxide-Sensitive Asymmetric Nanopores
2015
We describe the fabrication of a chemical-sensitive nanofluidic device based on asymmetric nanopores whose transport characteristics can be modulated upon exposure to hydrogen peroxide (H2O2). We show experimentally and theoretically that the current-voltage curves provide a suitable method to monitor the H2O2-mediated change in pore surface characteristics from the electronic readouts. We demonstrate also that the single pore characteristics can be scaled to the case of a multipore membrane whose electric outputs can be readily controlled. Because H2O2 is an agent significant for medical diagnostics, the results should be useful for sensing nanofluidic devices.
Current rectification by nanoparticle blocking in single cylindrical nanopores.
2014
Blocking of a charged pore by an oppositely charged nanoparticle can support rectifying properties in a cylindrical nanopore, as opposed to the usual case of a fixed asymmetry in the pore geometry and charge distribution. We present here experimental data and model calculations to confirm this fundamental effect. The nanostructure imaging and the effects of nanoparticle concentration, pore radius, and salt concentration on the electrical conductance–voltage (G–V) curves are discussed. Logic responses based on chemical and electrical inputs/outputs could also be implemented with a single pore acting as an effective nanofluidic diode. To better show the generality of the results, different ch…
Evaluation of the healing of precoated vascular dacron prostheses.
1991
Knitted and woven Dacron grafts commercially coated with bovine collagen, gelatin and human albumin were implanted end-to-side between the infrarenal aorta and the bifurcation in 35 growing pigs. Grafts were explanted after 4, 8 and 12 weeks and compared to 6 uncoated knitted prostheses preclotted with blood that served as a control. Uncoated grafts rapidly developed a firmly attached neointima lined with endothelium. Compared with coated grafts the thrombus-free area of uncoated grafts was significantly larger (P less than 0.05). The slow resorption of albumin resulted in a delayed and incomplete neointimal healing and failing graft incorporation. Although the bovine collagen was only mini…
Establishment of a pulmonary epithelial barrier on biodegradable poly-L-lactic-acid membranes
2019
Development of biocompatible and functional scaffolds for tissue engineering is a major challenge, especially for development of polarised epithelia that are critical structures in tissue homeostasis. Different in vitro models of the lung epithelial barrier have been characterized using non-degradable polyethylene terephthalate membranes which limits their uses for tissue engineering. Although poly-L-lactic acid (PLLA) membranes are biodegradable, those prepared via conventional Diffusion Induced Phase Separation (DIPS) lack open-porous geometry and show limited permeability compromising their use for epithelial barrier studies. Here we used PLLA membranes prepared via a modification of the…
Aortic valve-sparing root replacement from inside the aorta using three Dacron skirts preserving the native Valsalva sinuses geometry and stabilizing…
2009
We present an alternative idea for valve-sparing technique combining the advantages of the reimplantation and the benefits of the remodeling techniques. We replace the sinuses of Valsalva using three Dacron skirts from inside of the aorta. The physiological anatomy of the Valsalva sinuses and their dynamic properties are preserved and the aortic commissures displacement avoided. The distal rim of each Dacron skirt was anchored to the aorto-ventricular junction using Ticron (2-0) U stitches placed from the ventricular side to the aortic side. We stabilize the base of the aortic annulus to prevent future dilation.