The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analysed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation.

Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers.

Aims High-density lipoprotein (HDL) protects against atherosclerosis development. Defective functioning of HDL in Type 2 diabetes may be one cause of increased cardiovascular disease associated with Type 2 diabetes. HDL modulates low-density lipoprotein and cell membrane oxidation through the action of paraoxonase-1 (PON1), which is one of the major mechanisms by which HDL is anti-atherogenic. MethodsWe have compared the ability of HDL from Type 2 diabetic patients without coronary heart disease (CHD) ( n = 36) to metabolize membrane lipid hydroperoxides with HDL from healthy control subjects ( n = 19) and people with CHD but no diabetes ( n = 37).Results HDL from subjects with Type 2 diabetes and CHD metabolized 20% less membrane hydroperoxides than HDL from control subjects ( P < 0.05). The PON1-192RR was least efficient in all the study groups. PON1 was glycated in vivo : (7.5% control, 12% CHD, 17% Type 2 diabetes P < 0.01) with QQ isoforms most glycated. In vitro glycation of PON1 reduced its ability to metabolize membrane hydroperoxides by 50% ( P < 0.001); however, glyoxidation reduced it by 80% ( P < 0.001). In the control group only there was a significant negative correlation between PON1 activity and the ability of HDL to metabolize membrane hydroperoxides ( r = − 0.911, P < 0.001).Conclusions HDL from Type 2 diabetic patients without CHD has decreased ability to metabolize membrane lipid hydroperoxides, which could lead to increased susceptibility to cardiovascular disease.

Near-surface deformed layers, which are characterized by nano-sized fine grains, are generated in aluminum alloys by hot and cold rolling. During the rolling processes, the alloy surface and near-surface regions experience a high level of shear deformation that results in significant microstructure refinement, leading to formation of near-surface deformed layers with microstructures different from that of the underlying bulk alloy. Two types of near-surface deformed layers are observed. Type A is characterized by fine grains with grain boundaries decorated by oxide particles; type B is characterized also by fine grains but with the grain boundaries free of oxide particles. The high levels of shear deformation result in dynamic recrystallization. Together with mechanical alloying, this is responsible for the formation of the near-surface deformed layer. Furthermore, the structure in the near-surface deformed layer can survive the typical annealing process particularly if the grain boundaries are pinned by oxide particles.

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An investigation into corrosion inhibition properties of a primer coating containing lithium carbonate as corrosion inhibitive pigment for AA2024 aluminum alloy was conducted. It was found that, during neutral salt spray exposure, a protective film of about 0.2 to 1.5 μm thickness formed within the area where an artificial defect was introduced by scribing through the coating to the base alloy. This film showed a multilayered structure consisting of a relatively compact layer near the alloy substrate, a porous middle layer and a columnar outer layer. The thicknesses of the layers varied, as a consequence of the difference in the local concentration of lithium species leaching from the primer coating. The presence of the film in the scribed area significantly reduced corrosion of the alloy, with little consumption of the metal substrate within the scribed area during neutral salt spray exposure. Furthermore, the presence of the protective film resulted in a significant increase of impedance modulus, measured after the salt spray exposure.

The development of anodic films at a constant current density of 10 mA cm−2 has been studied for Mg-W alloys, containing 0.4 and 1.0 atom % W, in 3 M ammonium hydroxide/0.05 M ammonium phosphate electrolyte at 293 K. The structure, morphology, and composition of the films were determined by X-ray diffraction, scanning electron microscopy, atomic force microscopy, glow discharge optical emission spectroscopy, Rutherford backscattering spectroscopy, and nuclear reaction analysis. During anodizing to about 50 V, a relatively smooth film develops. Cross-sectional atomic force microscopy suggests the film may be finely porous. With an increase in voltage, the film transforms gradually to a coarse, porous morphology due to dielectric breakdown. The transformation coincides with a reduction in slope of the voltage-time response. Significant regions of both types of film morphology coexist during anodizing to 150 V. With further anodizing, a porous film, developed in the presence of sparking above about 270 V, eventually covers all of the macroscopic surface. Magnesium, phosphorus, oxygen, hydrogen, and nitrogen species are present throughout the film thickness at the resolution of the measurements. However, the films are initially free of tungsten species due to enrichment of tungsten in the alloy. The O:Mg atomic ratio is in the range 1.7 to 2.1, reducing with an increase in voltage for films formed up to 220 V, consistent with films composed primarily of hydroxide or oxyhydroxide. The P:O atomic ratio increases with an increase in voltage, starting at about 0.03 for voltages below 50 V and reaching 0.29 at 330 V. The films form at a reduced efficiency, typically about 40-50%. © 2001 The Electrochemical Society. All rights reserved.