Polyethylene terephthalate : factors affecting the impact behaviour

The following study forms part of a programme of work designed to produce a commercial moulding material based upon Polyethylene terephthalate. The work described relates specifically to the investigation of the impact characteristics of PET, and improvements that may be obtained in the impact strength by incorporation of the rubbery phase into the glassy PET matrix. The two phase systems studied in greatest detail were PET/Ionomer (Surlyn A) blends. A grafting reaction that was found to occur in the melt between these two polymers has been investigated in some detail using a Weissenberg Rheogoniometer. Also reported are studies of the crazing properties and nature of the craze structures produced in amorphous PET, together with a study of the crack velocity profiles obtained during the high velocity impact fracture of PET mouldings. This latter work led to a correlation of the topographical features observed on the fracture surface with the crack velocity. As a result a stick-slip mechanism of crack propagation was proposed, involving craze formation and fracture

Spin-dependent thermoelectric transport coefficients in near-perfect quantum wires

Thermoelectric transport coefficients are determined for semiconductor quantum wires with weak thickness fluctuations. Such systems exhibit anomalies in conductance near 1/4 and 3/4 of 2e^2/h on the rising edge to the first conductance plateau, explained by singlet and triplet resonances of conducting electrons with a single weakly bound electron in the wire [T. Rejec, A. Ramsak, and J.H. Jefferson, Phys. Rev. B 62, 12985 (2000)]. We extend this work to study the Seebeck thermopower coefficient and linear thermal conductance within the framework of the Landauer-Buettiker formalism, which also exhibit anomalous structures. These features are generic and robust, surviving to temperatures of a few degrees. It is shown quantitatively how at elevated temperatures thermal conductance progressively deviates from the Wiedemann-Franz law.Comment: To appear in Phys. Rev. B 2002; 3 figure

Evaluating the long-term conformation and hoof growth effects of starting hoof trimming at 5 months of age in New Zealand dairy goats

ABSTRACT: Hoof overgrowth is associated with poor conformation, an altered weight-bearing surface, and a reduction in the hoof's anatomic and functional integrity. As a result of housing systems that promote hoof overgrowth, hoof trimming is considered a priority in dairy goats. However, there are few data on the effects of the timing of first trimming on hoof conformation and growth rate. The aims of this study were (1) to evaluate the long-term effects of 2 different hoof trimming start times and (2) to investigate the pattern of hoof growth across the first 2 yr of life. Eighty 5-mo-old female Saanen-cross commercially housed dairy goats were allocated randomly to 1 of 2 treatments: (1) early trimmed (trimming beginning at 5 mo old; hooves were trimmed every 4 mo thereafter) and (2) late trimmed (trimming beginning at 13 mo old; hooves were trimmed every 4 mo thereafter). Using a combination of photographs and radiographs, hoof conformation, joint positions, and hoof wall length were assessed before the 13- and 25-mo trimming events. Hoof growth was assessed every 12 wk using caliper measurements. Overall, starting hoof trimming earlier had minor and inconsistent effects. However, detrimental changes in conformation and joint positions occurred between trimming events, particularly in the hind hooves, regardless of trimming treatment. At both assessments, there was a high percentage of overgrown toes and dipped heels, with the hind hooves being more affected compared with the front (overgrown toes at 13 mo, 97.1 vs. 79.1 ± 5.2%; overgrown toes at 25 mo, 91.7 vs. 56.3 ± 6.7%; dipped heels at 13 mo, 98.5 vs. 19.3 ± 5.0%; dipped heels at 25 mo, 88.3 vs. 4.9 ± 4.8%). In addition, at both assessments, the distal interphalangeal joint angle was greater in the hind hooves compared with the front (13 mo, 79.5 vs. 65.2 ± 1.7°; 25 mo, 79.0 vs. 66.7 ± 0.9°), whereas heel angles were less in the hind hooves compared with the front (13 mo, 41.8 vs. 57.1 ± 1.5°; 25 mo, 44.9 vs. 55.9 ± 1.1°). On average, the front hooves grew 4.39 mm/mo and the hind hooves grew 4.20 mm/mo. Early trimming did not have consistent effects on hoof growth rate. Importantly, our results suggest that trimming every 4 mo is not sufficient to prevent hoof overgrowth, the development of poor conformation, and detrimental changes in joint positions, particularly in the hind hooves. Furthermore, the detrimental changes may have masked any long-term treatment effects. Therefore, trimming frequency and age of first trimming should be considered when devising hoof care protocols for dairy goats housed in environments that do not offer opportunities for natural hoof wear

Patient-focused intervention to improve long-term adherence to evidence-based medications: a randomized trial

Item does not contain fulltextBACKGROUND: Nonadherence to cardiovascular medications is a significant public health problem. This randomized study evaluated the effect on medication adherence of linking hospital and community pharmacists. METHODS: Hospitalized patients with coronary artery disease discharged on aspirin, beta-blocker, and statin who used a participating pharmacy were randomized to usual care or intervention. The usual care group received discharge counseling and a letter to the community physician; the intervention group received enhanced in-hospital counseling, attention to adherence barriers, communication of discharge medications to community pharmacists and physicians, and ongoing assessment of adherence by community pharmacists. The primary end point was self-reported use of aspirin, beta-blocker, and statin at 6 months postdischarge; the secondary end point was a >/= 75% proportion of days covered (PDC) for beta-blocker and statin through 6 months postdischarge. RESULTS: Of 143 enrolled patients, 108 (76%) completed 6-month follow-up, and 115 (80%) had 6-month refill records. There was no difference between intervention and control groups in self-reported adherence (91% vs 94%, respectively, P = .50). Using the PDC to determine adherence to beta-blockers and statins, there was better adherence in the intervention versus control arm, but the difference was not statistically significant (53% vs 38%, respectively, P = .11). Adherence to beta-blockers was statistically significantly better in intervention versus control (71% vs 49%, respectively, P = .03). Of 85 patients who self-reported adherence and had refill records, only 42 (49%) were also adherent by PDC. CONCLUSIONS: The trend toward better adherence by refill records with the intervention should encourage further investigation of engaging pharmacists to improve continuity of care