This research studied seawater absorption ability and mechanical performance (before and after immersion in seawater) of two glass–fibre reinforced composites differing as regards the thermoset resin ...(isophthalic polyester or vinyl ester) but both used in boat manufacture. Experimental tests showed that vinyl ester has higher resistance to seawater absorption than isophthalic polyester due to the different cure rate and steric hindrance of the two resins. The vinyl resin cure reaction proceeded more slowly than for isophthalic polyester thereby enabling it to organize its linear macromolecular chains in a more compact structure with higher conversion rates. As a result, the vinyl ester resin composite had a lower water diffusion coefficient but higher chemical stability, stiffness and strength during its immersion in seawater than the isophthalic one.
To compare postcataract surgery anti-inflammatory regimens of intracanalicular dexamethasone insert and topical bromfenac on the incidence of cystoid macular edema (CME), iritis, pain, and ...photophobia.
Eyes of York Cataract & Laser Center, York, Pennsylvania.
Retrospective chart review.
Case records of 647 consecutive patients (1001 eyes) who underwent cataract surgery and received dexamethasone intracanalicular insert 0.4 mg (Group 1; 482 eyes) or topical nonsteroidal anti-inflammatory drug (NSAID) (bromfenac 0.075% 2 times a day) for 4 weeks postoperatively (Group 2; 519 eyes) were included. Both groups received intracameral moxifloxacin and phenylephrine/ketorolac. Patients with prior CME, vitreomacular traction, combined cataract/glaucoma surgery, and medication protocols different from those examined in this study were excluded.
Compared with the dexamethasone insert group, the topical NSAID group had a significantly lower incidence of CME (0.4% 2/519 vs 3.9% 19/482, P < .001) and photophobia (1.9% 10/519 vs 4.8% 23/482, P = .012). The incidence of breakthrough iritis (3.5% 18/519 vs 5.6% 27/482, P = .104) and pain also trended lower (4.0% 21/519 vs 5.4% 26/482, P = .314) in the topical NSAID group.
Topical NSAIDs were found to be more effective in controlling CME, pain, iritis, and photophobia after cataract surgery compared with the intracanalicular dexamethasone insert in the presence of intracameral phenylephrine/ketorolac.
To evaluate the outcomes of femtosecond laser–assisted arcuate keratotomy combined with cataract surgery in eyes with low-to-moderate corneal astigmatism.
Eyes of York Private Practice Ophthalmology ...Clinic, York, Pennsylvania, USA.
Retrospective case series.
This retrospective analysis included case records of patients with preexisting corneal astigmatism ranging from 0.5 to 2.0 diopter (D). Study parameters included corneal astigmatism, refractive astigmatism, and uncorrected (UDVA) and corrected (CDVA) distance visual acuities. The results, which were analyzed at 3 months postoperatively, included frequency distribution histograms, vector analysis, and single-angle polar plots.
The study comprised case records of 189 eyes of 143 patients (56 men and 87 women). The postoperative refractive astigmatism was reduced significantly compared with preoperative corneal astigmatism to 0.14 D ± 0.23 (SD) from 0.92 ± 0.34 D (P < .001). One hundred eighty-one eyes (95.8%) demonstrated postoperative refractive astigmatism of 0.5 D or less. The mean surgically induced change along the preoperative steep axis was −0.59 ± 0.56 D, and the change along the orthogonal axis was 0.01 ± 0.35 D. Postoperatively, 171 eyes (90.5%) had astigmatism angle of error of 15 degrees or less. The postoperative mean UDVA and CDVA were 0.09 ± 0.16 logarithm of the minimum angle of resolution (logMAR) and 0.02 ± 0.05 logMAR, respectively. One hundred seventy eyes (90%) had a postoperative UDVA of 20/30 or better. The results demonstrated stability at 12 months postoperatively. No intraoperative or postoperative arcuate keratotomy-related events were observed.
The results suggest that femtosecond laser–assisted arcuate keratotomy represents a safe and effective method for astigmatism correction at the time of cataract surgery with demonstrated stability of correction for at least 1 year postoperatively.
This research is a study on the degradation effects caused by seawater absorption of isophthalic polyester and vinyl ester resin employed in boat manufacture. Physical and mechanical tests of the ...resins were performed before and after the degradation. The results highlighted that the polyester resin is more degraded than the vinyl one, due to a different network organization of the two materials. The polyester has a biphasic structure with a low compactness, so water diffusion into the bulk is highly favored. The degradation occurs mainly by the leaching of small molecules extracted from the resin bulk by the water. Damages (cracks, holes, blisters) are evident and the resin loses its mechanical performance. The vinyl network is monophasic and compact, so avoids the entry of water; its degradation occurs differently, by a hydrolytic surface erosion of resin layers. In this way, it retains its bulk better compared to the polyester one.
Surface modification of ultra high molecular weight polyethylene (UHMWPE) is induced by ion implantation of different ions at 300 keV energy. The aim of this work was the chemical, physical and ...mechanical characterization of the modified material in order to know deep inside about the effect of the ion beam upon the polymer.
The irradiated surfaces are investigated by Raman spectroscopy, infrared absorption and micro-hardness analysis, scanning electron microscopy. Pin on disc measurements valuated the wear of the UHMWPE against a stainless steel probe; wear resistance increases of about 76% after the ion implantation. This result can be attributed to the ion bombardment inducing a micro-hardness increasing in the irradiated layers due to the high carbon surface concentration and cross-linking effects in the polymeric chains. The irradiated UHMWPE surfaces may find special applications to the field of the mobile prosthesis.
This article concerns the effect of pristine, carboxylic and amino-functionalised carbon nanotubes used as filler in epoxy-based nanocomposites. The amount of carbon nanotubes was within the range ...0.2–0.8 wt%. Their mechanical properties were investigated by means of flexural strength and resilience tests. The carbon nanotubes lead to an improvement of ductility and mechanical strength compared to the neat epoxy resin in the order: amino > carboxylic > pristine. The results of morphological, calorimetric, rheological and electrical conductivity tests suggest that this improvement is due to a good dispersion of the filler in the matrix and it occurs especially with low filler amounts (0.2–0.4 wt%) of amino carbon nanotubes. In the nanocomposites realised with amino-functionalised carbon nanotubes there is an interphase that creates a weak interfacial interaction between the filler and the epoxy resin. The thermal stability as well as the electrical conductivity of resin, is not appreciably improved after the addition of either functionalised carbon nanotubes.
▶ The polyethylene welding by using ns laser pulses is an important technique which permits to produce a mechanical resistant welded material.
Laser welding of plastics is a relatively new process ...that induces locally a fast polymer heating. For most applications, the process involves directing a pulsed beam of visible light at the weld joint by going through one of the two parts. This is commonly referred to as “through transmission visible laser welding”. In this technique, the monochromatic visible light source uses a power ns pulsed laser in order to irradiate the joint through one part and the light is absorbed in the vicinity of the other part.
In order to evaluate the mechanical resistance of the welded joint, mass quadrupole spectrometry, surface profilometry, microscopy techniques and mechanical shear tests were employed. The welding effect was investigated as a function of the laser irradiation time, nature of the polyethylene materials and temperature.
Each year, over 200,000 people are diagnosed with breast cancer in the United States. Although the use of biomarkers has the potential to guide preventive interventions and improve survival and ...quality of life, there have been few successes and many disappointments. In November 2005, the National Breast Cancer Coalition Fund convened a conference aimed at developing a patient-centred, strategic approach to breast cancer biomarker research. The consumers, clinicians, researchers, industry representatives and US regulators who served on the consensus panel developed a set of principles and recommendations to guide the field and ensure that biomarker research results in clinically important applications.
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