Assessment of airborne nanoparticles present in industry of aluminum surface treatments.

Conventional industrial processes are emission sources of unintended nanoparticles which are potentially harmful for the environment and human health. The aim of this study is to assess airborne nanoparticle release from aluminum surface treatment processes in various workplaces. Two direct reading instruments, a scanning mobility particle sizer to measure size distribution and a nanoparticle surface area monitoring to measure the surface area of particles deposited in the human lung, were employed to perform area monitoring. The lacquering paint was the process which released the highest concentration of particles from 10-487 nm (7.06 × 106 particles/cm3). The lacquering baths process emitted particles of the largest average size (76.9 nm) and the largest surface area deposited in the human lung (167.4 µm2/cm3). Conversely, the anodizing bath process generated particles of the smallest average size (44.3 nm) and the lowest human lung-deposited surface area (1.2 µm2/cm3). The total number of particles and the surface area can only be fairly correlated for environments in which the surface area presented higher values. The transmission electron microscopy analysis confirmed the presence of aluminum oxide particles of different dimensions near the LB and AB areas and polymeric-based particles near the LP areas. The findings of this study indicated that lacquering and anodizing surface treatments are indeed responsible for the emission of airborne nanoparticles. It also highlights the importance of control strategies as a means of protecting workers' health and environment.

Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

An efficient strategy to detect latent fingermarks on metallic surfaces.

The aim of this work is to use metal sputtering for the development of latent fingermarks on metallic surfaces by taking advantage of the prints' topography. In order to promote the preferential deposition onto fingerprints' ridges the deposition parameters should be optimized. After a previous selection, copper and gold thin films were deposited by magnetron sputtering onto stainless steel substrates where fingermarks were intentionally placed. After optimizing the deposition parameters, the influence of the fingermarks' age was studied. The quality of the developed fingermarks was evaluated visually and through optical and scanning electron microscopy. The morphology of the copper and gold thin films was examined by high resolution scanning electron microscopy. The preferential magnetron sputtering deposition of copper and gold thin films, 20-30 nm thick, allows latent fingermarks to be successfully developed. The gold films are more promising, especially for detecting non-fresh fingermarks and for conserving the developed marks. It was possible to detect the contours of the ridges and localize minutiae features in a one-month aged impression developed by gold deposition. These films present discontinuous surface and columnar cross-sections, while copper thin films have a featureless morphology.

TEM characterization of As-deposited and annealed Ni/Al multilayer thin film.

Reactive multilayer thin films that undergo highly exothermic reactions are attractive choices for applications in ignition, propulsion, and joining systems. Ni/Al reactive multilayer thin films were deposited by dc magnetron sputtering with a period of 14 nm. The microstructure of the as-deposited and heat-treated Ni/Al multilayers was studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) in plan view and in cross section. The cross-section samples for TEM and STEM were prepared by focused ion beam lift-out technique. TEM analysis indicates that the as-deposited samples were composed of Ni and Al. High-resolution TEM images reveal the presence of NiAl in small localized regions. Microstructural characterization shows that heat treating at 450 and 700°C transforms the Ni/Al multilayered structure into equiaxed NiAl fine grains.

In situ TEM study of grain growth in nanocrystalline copper thin films.

Nanocrystalline metals demonstrate a range of fascinating properties, including high levels of mechanical strength. However, as these materials are exposed to high temperatures, it is critical to determine the grain size evolution, as this process can drastically change the mechanical properties. In this work, nanocrystalline sputtered Cu thin films with 43 +/- 2 nm grain size were produced by dc-magnetron sputtering. Specimens were subsequently annealed in situ in a transmission electron microscope at 100, 300 and 500 degrees C. Not only was grain growth more evident at 500 degrees C but also the fraction of twins found. An analysis of grain growth kinetics revealed a time exponent of 3 and activation energy of 35 kJ mol(-1). This value is explained by the high energy stored in the form of dislocation, grain boundaries and twin boundaries existing in nanocrystalline copper, as well as the high probability for atoms to move across grains in nanocrystalline materials.

Ti/Al nanolayered thin films.

Ti/Al multilayer thin films with modulation periods up to 100 nm were characterised at the nanoscale level. The Ti/Al multilayers were deposited onto stainless steel substrates by magnetron sputtering from Ti and Al targets. Time on flight secondary ion mass spectroscopy analyses were carried out in order to verify the layered structure and check both the effect of contaminants such as oxygen and the intermixing at the interfaces. Structural analyses were performed by X-ray diffraction and transmission electron microscopy. The deposition procedure gives rise to a nanometric multilayer structure, where elemental Ti and Al can be identified, even for the lowest period multilayer (4 nm). The multilayer films consist of a-Ti plus Al with nanometric grain sizes. The grain size is determined by the multilayer modulation period, having both similar values. In the as-deposited state no intermetallic compounds were detected. During the deposition process some intermixing occurred at the interfaces, which should assume some importance in decreasing the heat of the exothermic reaction between Ti and Al, particularly as the modulation period decreases.

Mechanical characterization of a functionally graded nanocomposite thin film.

Functionally graded nanocomposite thin films (2D-FGM), of sub-micrometric thickness, were co-deposited from austenitic stainless steel (316L (AISI)) and poly(tetrafluoroethylene) targets by r.f. magnetron sputtering. All the deposition parameters were kept constant except for the electrical characteristics applied to polymeric target. XPS revealed in the films fluorine contents between 0 and 60 at%. The TEM analysis revealed the evolution towards a nanocomposite structure with an increase in fluorine content (from 0 to 20 at%). For the higher fluorine contents the formation of a ceramic phase, FeF2, is the main structural feature. The hardness is higher for the films with the lowest fluorine concentration due to higher chromium carbides content. The residual stresses of the 2D-FGM are essentially compressive with values up to 2.2 GPa. The values of the friction coefficient of the nanocomposite thin films are in the range of 0.66-0.71, an exception is for the highest fluorine content where the value is 0.31.

The effect of nitrogen on the formation of nanocrystalline copper thin films.

The current success of nanocrystalline materials is due to their unusual and promising properties compared to coarser grain size materials. However, maintaining the nanocrystalline character during processes or applications is not an easy task, due to the tendency towards grain growth exhibited by nanocrystalline materials. It is well known that the addition of solutes with a strong affinity for grain boundary segregation can act as pinning centers and inhibit grain growth, particularly during the manufacturing process. However, the ideal is to use these elements/compounds only during manufacturing, and after that these elements must disappear in order to attain the desirable properties. The aim of this study is to produce nanocrystalline Cu-based thin films through controlled addition of nitrogen to inhibit grain growth. A detailed chemical composition, structural and grain size analysis of these thin films was made by Electron Probe Microanalysis (EPMA), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The results indicate that introduction of nitrogen, even in small amounts, leads to a significant decrease in grain size, particularly if Cu3N is not yielded in the thin film during the deposition process.

Thin films with chemically graded functionality based on fluorine polymers and stainless steel.

Thin films of stainless steel and poly(tetrafluoroethylene) were co-deposited, by radiofrequency magnetron sputtering, in an inert atmosphere in order to produce a functionally graded material as a coating on a traditional biomaterial, where non-ferromagnetic characteristics and improved wettability must be ensured. These thin films are intended to modify the surface of SS316L used in stents, where the bulk/thin film couple should be regarded as a single material. This requires excellent adhesion of the coating to the substrate. All coatings were deposited with an average thickness of 500 nm. The chemical and phase characterization of the surface revealed that, with the increase in F content, the thin film evolves from a ferritic phase (alpha) to an amorphous phase with dispersion of a new crystalline ceramic phase (FeF(2)). For intermediate F content values, an austenitic (111) phase (gamma) was present. Bearing in mind the envisaged application, the best results were attained for thin films with a fluorine content between 10 and 20 at.%.

Clinics in diagnostic imaging (113).

Primary hyperaldosteronism is described in a 27-year-old Brazilian woman from an endemic area of schistosomiasis. She presented with hypokalaemia, cramps and polyuria, refractory hypertension, plasma aldosterone of 40.7 ng/dL and aldosterone/renin activity ratio higher than 100, due to an associated long-standing unsuspected aldosteronoma. Computed tomography showed a well-defined ovoid right adrenal mass, which was subsequently resected and confirmed to be an aldosteronoma. During subsequent follow-up visits, she remained asymptomatic, normokalaemic, and required no antihypertensive drugs. The differential diagnoses of refractory hypertension are discussed.