Polyaniline-coated iron: studies on the dissolution and electrochemical activity as a function of pH

Polyaniline coatings were electrodeposited from an oxalic acid solution onto iron and their electrochemical activity and corrosion protection properties studied as a function of pH. It was found that the coating (emeraldine salt) had a limited effect on the corrosion protection of iron in acidic solutions. However, in an alkaline borate solution, where the conducting polyaniline was converted to the emeraldine base, the coating had a clear beneficial effect on the local breakdown of iron by chloride anions; much higher pitting potentials were recorded following a 2 h immersion period for the polyaniline-coated substrate relative to the uncoated electrode. Relatively small anions, such as acetates, nitrates and borates, were transported readily across the polymer interface. However, the emeraldine base inhibited the transport of the much larger ethylenediamine tetraacetate (EDTA) species to the iron interface, preventing complexation of the iron by EDTA.     

Modulation of Macrophage Fatty Acid Content and Composition by Exposure to Dyslipidemic Serum in Vitro

Macrophages in arterial walls accumulate lipids leading to the development of atherosclerotic plaques. However, mechanisms underlying macrophage lipid accumulation and foam cell formation are often studied without accounting for risk factors such as dyslipidemia. We investigated the effect of varying concentrations of triglyceride (TG) within physiological range on macrophage fatty acid (FA) accumulation and expression of cholesterol efflux proteins. Human monocytes were cultured in media supplemented with 10% sera containing low (0.7 mmol/L) to high (1.4 mmol/L) TG. The resulting macrophages were harvested after 10 days for analysis of FA content and composition and expression of genes involved in lipid metabolism. Exposure to higher TG and lower HDL concentrations in media increased macrophage lipid content. Macrophages exposed to higher TG had increased total FA content compared with controls (876 μg/mg protein vs. 652 μg/mg protein) and greater proportions of C16:0, C18:1 and C18:2. Macrophage expression of both ABCA1 and ABCG1 cholesterol efflux proteins were reduced when higher TG concentrations were present in the media. Expression of scavenger receptor CD36, involved in lipoprotein uptake, was also downregulated in macrophages exposed to higher TG. Culturing macrophages in conditions of higher versus lower TG influenced macrophage FA content and composition, and levels of regulatory proteins. Replicating in vitro levels of dyslipidemia encountered in vivo may provide an informative model for investigation of atherogenesis.     

An electrochemical study in aqueous solutions on the binding of dopamine to a sulfonated cyclodextrin host

Clear evidence for the formation of a weak inclusion complex between dopamine (DA) and a sulfonated β-CD host in aqueous solution was obtained using a combination of electrochemical approaches. Using cyclic voltammetry, a distinct increase in the oxidation potential of DA and a reduction in the peak oxidation current were observed on adding an excess concentration of the sulfonated β-CD to the electrolyte solution. Equally, a clear increase in the half-wave oxidation potential of DA was observed in the presence of the sulfonated β-CD using rotating disc voltammetry. The association constant, K, was computed as 331.3 ± 5.8, indicating the formation of a weak inclusion complex, while a 1:1 stoichiometry for the inclusion complex was deduced from a Job's plot analysis. The rate constant for the oxidation of DA was found to decrease on formation of the inclusion complex. This was attributed to higher reorganization energy for the oxidation of the included DA. These changes in the electrochemistry of DA were not observed when an excess of the smaller sulfonated α-CD was added to the electrolyte, indicating that these variations are not connected with simple electrostatic interactions between the protonated DA and the anionic sulfonated groups. It is proposed that the aromatic ring of the DA molecule includes within the cyclodextrin cavity, while the protonated amine group remains outside the cavity, bound electrostatically with the anionic sulfonated groups.     

Prevalence of Campylobacter and Salmonella in raw chicken on retail sale in the republic of Ireland

To assess the current risks to consumers from Campylobacter and Salmonella in raw chicken products sold in the Republic of Ireland, a retail survey was undertaken to define their prevalence. Samples (n = 510) were analyzed using protocols based on ISO 10272-1:2006 and ISO 6579:2002. Processor codes on pack labels showed that 67% of samples were produced in the Republic of Ireland and 25% in the United Kingdom. Salmonella was present in 5.1% of samples, but the eight serovars found caused less than 7% of human salmonellosis reported in the Republic of Ireland. The results suggest that on-farm controls to limit Salmonella infection of broilers have been successful and that in Ireland raw chicken is not a significant cause of salmonellosis in humans. The overall prevalence of Campylobacter spp. was 84.3%. Isolation by the ISO method found 52.7% of samples to be positive, but overgrowth by contaminants was frequently evident. Therefore, in addition to enrichment, an homogenized sample was plated directly onto modified charcoal cefoperazone deoxycholate agar, and this detected a further 31.6%. Speciation of isolates (n = 426) determined that 67% were Campylobacter jejuni and 32% were Campylobacter coli. These species are the most common cause of campylobacteriosis in man. The results indicate that there is a need for poultry producers to introduce interventions to minimize the exposure of consumers in the Republic of Ireland to Campylobacter spp., as has been successfully done for Salmonella.     

Ancestrally high elastic modulus of gecko setal beta-keratin.

Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1MPa. Geckos possess subdigital adhesives composed mostly of beta-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of beta-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of beta-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa +/- 0.15s.e.; n=24 setae) and Ptyodactylus hasselquistii (1.4 GPa +/- 0.15s.e.; n=24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.     

Mantle irradiation in Hodgkin's disease. An analysis of technique, tumor eradication, and complications

Analysis of the treatment and follow-up records of 377 Hodgkin's disease patients who received mantle irradiation but no planned chemotherapy reveals an overall supradiaphragmatic relapse rate of 21%. Complications of treatment included symptomatic pulmonary radiation reaction (20%), pericarditis (13%), Lhermitte's sign (15%), and thyroid dysfunction (13%). The addition of a subcarinal block after 2500 to 3500 rads and the use of the thin lung block technique in selected patients have reduced the incidence of pulmonary and pericardial complications to less than 5% without sacrificing local control. Further modifications in technique and treatment policy are discussed in terms of improving the therapeutic ratio.