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Parylene is commonly used as thin film polymer for MEMS devices and smart materials. This paper investigates the impact on bulk properties due to annealing various types of Parylene films. A thin film of Parylene N, C and a hybrid material consisting of Parylene N and C were deposited using a standard Gorham process. The thin film samples were annealed at varying temperatures from room temperature up to 300 °C. The films were analyzed to determine the mechanical and crystallinity effects due to different annealing temperatures. The results demonstrate that the percentage of crystallinity and the full-width-half-maximum value on the 2θ X-ray diffraction scan increases as the annealing temperature increases until the melting temperature of the Parylene films was achieved. Highly crystalline films of 85% and 92% crystallinity were achieved for Parylene C and N respectively. Investigation of the hybrid film showed that the individual Parylene films behave independently to each other, and the crystallinity of one film had no significant impact to the other film. Mechanical testing showed that the elastic modulus and yield strength increase as a function of annealing, whereas the elongation-to-break parameter decreases. The change in elastic modulus was more significant for Parylene C than Parylene N and this is attributed to the larger change in crystallinity that was observed. Parylene C had a 112% increase in crystallinity compared to a 61% increase for Parylene N, because the original Parylene N material was more crystalline than Parylene C so the change of crystallinity was greater for Parylene C. [ABSTRACT FROM AUTHOR]

A narrow bandwidth is one of the most challenging issues that vibrational energy harvesters have to overcome. This paper demonstrates a novel method of broadening the bandwidth without significantly reducing the peak output voltage. The method uses a liquid filled mass to create a sliding mass effect in order to broaden the bandwidth. The fluid mass increased the full-width-half-maximum (FWHM) value from 1.6 Hz to 4.45 Hz with no significant decrease in peak-to-peak voltage when compared to an empty mass. The fluid filled mass has a non-linear mass distribution during low frequency, high acceleration applications. [ABSTRACT FROM AUTHOR]

Effect of folic acid on methionine and homocysteine metabolism in end-stage renal disease.Background.The pathogenesis of hyperhomocysteinemia in end-stage renal disease (ESRD) is unclear. Folic acid lowers, but does not normalize, the plasma homocysteine level in patients with ESRD, but its effect on whole body metabolism of homocysteine is unknown.MethodsWe studied the effect of 3 weeks of oral treatment with 5 mg folic acid per day on homocysteine metabolism in six chronic hemodialysis patients and six healthy controls. Primed, continuous infusions with[2H3-methyl-1-13C] methionine were used to determine flux rates of methionine transmethylation, homocysteine remethylation, and homocysteine transsulfuration. Metabolic homocysteine clearance was defined as the ratio of transsulfuration and plasma homocysteine level.Results.Folic acid treatment lowered plasma homocysteine significantly by 39% (95% CI 5 to 73) in the ESRD group, but plasma homocysteine remained higher than baseline values in the control group. In ESRD patients, homocysteine remethylation and methionine transmethylation rate increased by 34% (95% CI 5 to 62) and 22% (95% CI 5 to 39), respectively (i.e., levels that were similar to the baseline values of the control group). Transsulfuration rate and metabolic homocysteine clearance were not significantly altered by folic acid treatment in both the ESRD and the control group.Conclusion.In ESRD patients, folic acid treatment lowers, but does not normalize plasma homocysteine, whereas homocysteine remethylation and methionine transmethylation increase to levels found in untreated healthy controls. These findings indicate a persistent, folate-independent, defect in metabolic homocysteine clearance in ESRD. [ABSTRACT FROM AUTHOR]

This randomised double-blind, placebo-controlled, clinical trial investigated the effect of 3 months of treatment with calcium dobesilate on endothelium-dependent vasodilation, markers of endothelial function, blood pressure, and markers of oxidation in obese, male smokers. Vascular effects may depend on the type of vessel and we, therefore, investigated both smaller arteries, i.e. resistance arteries and small arterioles, and large conduit arteries. Vascular function was measured by acetylcholine- and sodium-nitroprusside-mediated vasodilation, and capillary recruitment, in the skin microcirculation; by forearm blood flow (FBF) responses to several agonists and to N-G-monomethyl l-arginine (l-NMMA) in the forearm vascular bed; by flow-mediated vasodilation in the brachial artery; and by determination of soluble levels of vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1) and E-selectin. Twenty-eight individuals received dobesilate and 24 placebo. No effect of calcium dobesilate on endothelial function, blood pressure or markers of oxidation was observed compared with placebo. The difference in acetylcholine-mediated vasodilation in the microcirculation was −52.1%-point (95% confidence interval −132.8 to 28.1); in sodium-nitroprusside-mediated vasodilation in the microcirculation, 2.6%-point (−95.1 to 100.2); in capillary recruitment, 2.5%-point (−6.8 to 11.7); in acetylcholine-induced increases in FBF (n=28), 23%-point (−173 to 126); in l-NMMA-induced reduction of basal FBF, −2.8%-point (−29.3 to 23.8); in flow-mediated vasodilation of the brachial artery, 0.3%-points (−2.7 to 3.3); in 24-h systolic blood pressure, 2.1 mmHg (−1.3 to 5.5); in soluble VCAM-1, 54 ng/ml (−8 to 115); in soluble ICAM-1, 9 ng/ml (−49 to 67); in sE-selectin, −17 ng/ml (−44 to 11); in ketocholesterol 5 nM (−17 to 26); and in oxidised LDL −1.6 U/l (−6.7 to 3.5). We have shown that endothelial function, blood pressure, and markers of oxidation were not affected by 3 months of treatment with calcium dobesilate in mildly obese, smoking men. Thus, our data provide no evidence of an effect on vascular function of calcium dobesilate in humans. [Copyright &y& Elsevier]

Investigates the metabolism of homocysteine in chronic renal failure. Role of hyperhomocysteinemia in the progression of atherothrombotic disease; Relationship between glomerular filtration rate and plasma homocysteine level; Impairment of homocysteine remethylation in dialysis patients.

A letter to the editor is presented in response to an article by David E.L. Wilcken and Lars Brattström on hyperhomocysteinemia and cardiovascular disease.

Effect of fluvastatin on endothelium-dependent brachial artery vasodilation in patients after renal transplantation. Background. Hypercholesterolemia may affect both endothelial function and arterial distensibility (DC). Renal transplant recipients (NTX) exhibit advanced structural and functional alterations of arterial vessel walls. The aim of this double-blind, randomized trial was to evaluate the effects of fluvastatin (FLU) on brachial artery flow-mediated vasodilation (FMD) and DC in hypercholesterolemic NTX. Methods. Eighteen NTX received FLU 40 mg/day and 18 NTX placebo (PLA). Before and after six months of treatment, the brachial artery diameter and DC at rest were measured by a Doppler frequency analysis in the M mode, and then changes in diameter during reactive hyperemia (to assess endothelial-dependent FMD) and after 400 μg sublingual nitroglycerin (to assess endothelium-independent vasodilation—NMD). Results. FLU, but not PLA, treatment resulted in significant decreases in total (from 288 ± 10 to 239 ± 8 mg/dL, P < 0.05) and low-density lipoprotein cholesterol (from 182 ± 779 to 138 ± 8 mg/dL, P < 0.05). Blood pressure did not differ between FLU- and PLA-treated patients and was not affected by either treatment. Also, the brachial artery baseline diameter was not different between groups and was not affected by FLU or PLA. Brachial artery flow at rest and during reactive hyperemia as measured by pulsed Doppler did not differ between groups. Brachial artery FMD increased with FLU from 0.23 ± 0.08 to 0.54 ± 0.08 mm (P < 0.05), whereas PLA did not alter FMD (0.22 ± 0.07 vs. 0.14 ± 0.05 mm at baseline and after six months of PLA treatment, respectively, P = NS). In contrast, NMD did not change significantly with either treatment (0.76 ± 0.13 vs. 0.83 ± 0.15 mm at baseline and after 6 months of FLU treatment, respectively, P = NS, and 0.64 ± 0.09 vs. 0.66 ± 0.10 mm at baseline and after 6 months of PLA treatment, respectively, P = NS). Also, brachial artery DC was not altered by FLU (6.4 ± 1.0 vs. 5.8 ± 0.6 × 10-3 /kPa, P = NS) or PLA treatment (5.8 ± 0.6 vs. 6.8 ± 0.8 × 10-3 /kPa, P = NS). Conclusions. In hypercholesterolemic NTX, the HMG-CoA reductase inhibitor FLU significantly improves brachial artery FMD as a measure of endothelial function after six months of treatment. In contrast, FLU does not have a beneficial effect on brachial artery DC. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the electrochemical characterisation of a range of gold and platinum microelectrode arrays (MEAs) fabricated by standard photolithographic methods. The inter-electrode spacing, geometry, numbers and dimensions of the electrodes in the arrays were found to influence the voltammetric behaviours obtained. Excellent correlation was found between experimental data and theoretical predictions employing published models of microelectrode behaviour. Gold MEAs were evaluated for their applicability to copper determination in a soil extract sample, where agreement was found between the standard analytical method and a method based on underpotential deposition—anodic stripping voltammetry (UPD-ASV) at the MEAs, offering a mercury-free alternative for copper sensing. [Copyright &y& Elsevier]