Search results for "Polymers"
showing 10 items of 3567 documents
Prevalence of cataract after collagen copolymer phakic intraocular lens implantation for myopia, hyperopia, and astigmatism
2015
Purpose To evaluate the prevalence of cataract after Implantable Collamer Lens phakic intraocular lens (pIOL) implantation with different models at different ages and for different refractive powers. Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Design Retrospective nonrandomized clinical study. Methods The pIOL (models V4, V4b, or V4c) was implanted in all cases. Results The study included 3420 eyes (1898 patients). The mean patient age at surgery was 31.2 years ± 6.4 (SD) (range 18 to 50 years) and the mean spherical refractive error, −7.27 ± 5.24 diopters (D) (range −26.5 to 12.5 D). Twenty-one eyes (0.61%) of 15 patients had pIOL explantation (all model V4) because c…
Collagen copolymer posterior chamber phakic intraocular lens supported by the ciliary sulcus to treat myopia: One-year follow-up
2014
Purpose To evaluate the predictability, stability, safety, and efficacy of Visian V4b Implantable Collamer Lens phakic intraocular lens (pIOL) implantation to treat varying degrees of myopia. Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Design Prospective nonrandomized clinical study. Methods The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, pIOL vault, and adverse effects were evaluated 12 months postoperatively. Results The study enrolled 121 eyes (68 patients). The mean spherical equivalent decreased from −8.61 diopters (D) ± 3.41 (SD) (range −18.75 to −2.25 D) preoperatively to −0.18 ± 0.29 D (range −1.25 to 0.50 D) 12 months postoper…
Cutaneous Recording and Stimulation of Muscles Using Organic Electronic Textiles
2016
International audience; Electronic textiles are an emerging field providing novel and non-intrusive solutions for healthcare. Conducting polymer-coated textiles enable a new generation of fully organic surface electrodes for electrophysiological evaluations. Textile electrodes are able to assess high quality muscular monitoring and to perform transcutaneous electrical stimulation.
Maxillary bone necrosis following the use of formaldehyde containing paste: management and case series
2007
Paraformaldehyde is used both as a disinfectant and to devitalise inflamed pulps when local anaesthesia is ineffective. Despite the clinical benefits, paraformaldehyde is not confined to the pulp, but penetrates the dentine and is gradually released as formaldehyde. This case series describes the effects on periodontal and bone tissues of paraformaldehyde used as a devitalising or disinfectant agent.
Formation of supramolecular aggregates by hydrogen bonding based on bispyrimidine and bisbarbituric acid
1997
Hydrogen bonds between bispyrimidine and bisbarbituric acid in equal molar ratio can lead to the formation of supramolecular aggregates. This is established by TEM, IR and DSC measurements. Additionally, WAXS pattern showed that the aggregate is of laminar structure. Both the hydrolysis of this system and termination of the aggregate's growth were studied.
Thermodynamic Behavior of Non-Ionic Tri-block Copolymers in Water at Three Temperatures
2006
Apparent molar volumes (V Φ) of aqueous solutions of some copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, were determined as functions of concentration at three temperatures. Viscosity measurements were also carried out on some of these systems. The effects studied include how the molecular architecture and the molecular weight affect the aggregation of the copolymer, keeping constant the EO/PO ratio. Modeling of the volumetric data yielded the partial molar volume of the copolymer in the standard (V°) and the aggregated (V M) states, as well as the equilibrium constant for micellization and the aggregation number. Analysis of the viscosity data supported the insigh…
Dynamic Mechanical Behavior Analysis of Flax/Jute Fiber-Reinforced Composites under Salt-Fog Spray Environment
2020
Over the last decades, natural fiber-reinforced polymer composites (NFRPs) gained great attention in several engineering fields thanks to the reduction of the environmental impact and the end-of-life cost disposal. Unfortunately, the use of NFRPs is limited, mainly due to their weak resistance against humid environments. Since limited literature is available about the evolution of the dynamic mechanical response of NFRPs under aggressive environments, this paper aims to investigate the damping properties of flax, jute and flax/jute epoxy composites exposed to salt-fog up to 60 days. Furthermore, sodium bicarbonate fiber treatment was performed to improve the composites&rsquo
Beyond Biodegradability of Poly(lactic acid): Physical and Chemical Stability in Humid Environments
2017
International audience; Poly(lactic acid) (PLA) is the most traded biodegradable and biobased material. It is largely used as ecofriendly substitute of conventional plastics. Nevertheless, one of the main limiting factors is its water sensitivity. PLA reacts with water and is hydrolyzed during time, which determines its performance. Limited information related to the hydrolysis mechanism driven by water in vapor state is available in scientific literature. Literature is mainly focused on the effects of water in liquid state. This lack of information is of significant importance, since PLA interacts with water in both phases. This work was aimed to give a full depiction of the chemical and p…
The influence of the nature of the surface oxide on the adhesive fracture energy of aluminium-bonded joints as measured by T-peel tests
2008
Abstract Modification of aluminium alloy substrates microstructure and morphology by depositing new oxide layers on top of the metal surface has been investigated, with the aim of improving adhesion. The effect of treating the metal with boiling water or immersing it in a cerate bath has been studied by means of electron microscopy, contact angle measurements and peeling tests. The formation of pseudoboehmite layers or cerium conversion coatings both led to an increase in joint's adhesive fracture energy and more durable adhesive bonds with respect to joints obtained with “mechanically grinded only” substrates. Differences in the performance of the bonded joints has been discussed in terms …
Modelling of proton and metal exchange in the alginate biopolymer.
2005
Acid-base behaviour of a commercial sodium alginate extracted from brown seaweed (Macrocystis pyrifera) has been investigated at different ionic strengths (0.1or=I/mol l(-1)or=1.0) and in different supporting electrolytes (Et4NI, NaCl, KCl, LiCl, NaCl+MgCl2), with the aim of examining the influence of ionic medium on the proton-binding capacity and of quantifying the strength of interaction with light metal ions in the perspective of speciation studies in natural aqueous systems. Potentiometric ([H+]-glass electrode) and titration calorimetric data were expressed as a function of the dissociation degree (alpha) using different models (Henderson-Hasselbalch modified, Högfeldt three parameter…