Chromium electrodeposition from Cr(VI) low concentration solutions

This work presents a study of a hard chromium plating process using low concentration H₂CrO₄ baths. In particular, the effect of different values of CrO₃/H₂SO₄ ratio on coating properties such as adhesion, hardness, surface roughness, apparent density and microstructure were considered. To increase the solution conductivity, avoiding long deposition times and low throwing power typical of dilute solutions, the behaviour of various inorganic compounds was investigated. Specifically, the compounds suitable for obtaining brighter coatings with lower surface roughness values than those obtained using Fink’s solutions were Na₂SO₄ and Al₂(SO₄)₃ × 18H₂O. A bath composition was identified, with a limited use of Cr(VI) in a solution able to produce coatings with a better surface roughness than those of conventional industrial baths.     

Dynamic quorums for DHT-based enterprise infrastructures

Peer-to-peer systems (P2P) have become a popular technique to design large-scale distributed applications in unmanaged inter-domain settings, such as file sharing or chat systems, thanks to their capabilities to self-organize and evenly split the load among peers. Recently, enterprises owning a large IT hardware and software infrastructure started looking at these P2P technologies as a means both to reduce costs and to help their technical divisions to manage huge number of devices characterized by a high level of cooperation and a relatively low churn. Gaining a quick exclusive access to the system for maintenance or auditing purposes in these enterprise infrastructures is a fundamental operation to be implemented. Conversely, this kind of operation is usually not an issue in the previously mentioned inter-domain setting, where peers are inherently independent and cannot be managed.     

Engineering electrospun nanofibrillar surfaces for spinal cord repair: a discussion

BACKGROUND: The design of implants comprised of biodegradable electrospun nanofibers for the purpose of bridging injuries in damaged spinal cord is discussed. Electrospun nanofibers structurally mimic the extracellular matrix on which neurons and other cell types grow in vivo. This property has created great interest for their use in tissue engineering applications. However, their employment as biomimetic surfaces for such in vivo applications is still in its infancy. RESULTS: A nonwoven fabric comprised of electrospun polyamide nanofibers supported modest axonal regeneration in injured adult rat spinal cord. Covalent modification of the nanofibers with a bioactive peptide derived from the neuroregulatory extracellular matrix molecule tenascin‐C enhanced the ability of the nanofibers to facilitate axonal regrowth. However, the random orientation of the nanofibrillar fabric folds was an impediment to the forward movement of axons. CONCLUSIONS: Polyamide nanofibers covalently modified with neuroactive molecules provide a promising material for grafts to promote spinal cord regeneration. However, for the proper guidance of regrowing axons, attention must be paid to the engineering of ordered nanofibrillar structures. Copyright © 2007 Society of Chemical Industry     

An evaluation of the potential of the use of wasted hydroelectric capacity to produce hydrogen to be used in fuel cells in order to decrease CO2 emissions in Brazil

The use of water wasted in hydroelectric plants as normalization dam excess, which constitute a hydrodynamic potential useful to generate electric energy which can be subsequently used to produce hydrogen and its subsequent consumption in fuel cells, has been considered as an alternative for hydraulic energy-rich countries like Brazil. The case is examined in which all the water wasted in the hydroelectric plants, spilled by dam gates to maintain acceptable water levels, from the 101 largest Brazilian hydroelectric plants was used to produce hydrogen. During the year of 2008, the electric energy produced from this utilisation would have been equivalent to 106.2 TWh, an amount that corresponds to an increase of ca. 30% of the total electric energy produced in the country. Furthermore, if this amount of hydrogen was used in the replacement of internal combustion vehicles by fuel cells, this would have prevented the production of 2,000,000 tons of CO₂ emissions per day. The economic balance (cost of electricity produced using the wasted water minus cost of gasoline consumed) indicates a savings of ca. 200 million US$. This plan would also significantly decrease production and release of greenhouse gases.     

SENSORLESS DETECTION OF TOOL BREAKAGE IN MILLING

One of the most important research topics in the area of Intelligent Manufacture Systems (IMS) is the automatic detection of tool breakage, wear of chipping during the cutting process. Sensor-based techniques are available for cutting force measurements, but there are drawbacks in this approach in cost and idle times. This work proposes a sensorless monitoring system for tool monitoring in order to detect breakage and chipping by exploiting the wavelet transform and a neural network. Previous works have made use of these tools for monitoring several machining parameters, but we propose an integrated low-cost approach to detect quickly the changes in the tool integrity for monitoring. The system output produces an accurate detection of the tool integrity that enables the system to prevent damage due to tool breakage. This approach allows for an industrial solution to be developed.     

Gamma-ray emission gauge for solar salt level in a tank

One of the most investigated heat transfer fluid or heat storage medium in the field of thermal solar conversion is the “solar salt”, a mixture of nitrates NaNO₃/KNO₃, 60/40% by weight, respectively. The content of potassium in this fluid allows exploiting the self activity of the isotope ⁴⁰K to perform measurements useful for control or diagnostics of a solar plant. Here an experimental test on the non-invasive measurement of the salt level in a tank by means of gamma-ray spectrometry is shown.     

Nutritional quality and safety of European perch (Perca fluviatilis) from three lakes of Central Italy

European perch (Perca fluviatilis) harvested from three lakes of Central Italy were studied in different seasonal periods of a year to evaluate their nutritional quality and some safety aspects related to the pollution of the aquatic environment. The lakes considered, located in the Latium region, differed with respect to their volcanic (Bolsena and Bracciano Lakes) or artificial (Salto Lake) origin. Fillets of fish caught in the three lakes were characterised by good protein (17–19%) and mineral contents and low lipid levels (0.6–1.2%) throughout the year. Total lipids were characterised by low cholesterol levels (41.9–74.7 mg/100 g) and high percentages of total n − 3 polyunsaturated fatty acids (27.7–33.8% of total fatty acids), in particular docosahexaenoic acid (14.2–25.3% of total fatty acids). The qualitative analysis of the stomach content of perch confirmed their predatory feeding behaviour. The chemical and nutritional profiles of perch from the three lakes were comparable except for rubidium and cesium levels, which were higher in the muscle tissues of perch from the volcanic lakes. These minerals may represent elements of traceability of the origin of fish. Low levels of organochlorine pesticides and polychlorinated biphenyls, well below the Italian and European action limits, were detected in the muscle tissue of perch from all three lakes.     

Thermal simulation of a single particle in a falling-particle solar receiver

A transient simulation of the heat transfer in a particle directly heated by the sun, in a falling-particle receiver, is presented. The local temperature can have a non-uniform distribution, that depends on many factors, such as the size of the particle, its rotation, and the exposition time. This fact should be considered when studying the material resistance and aging, or direct chemical reactions in the falling particle. The single-particle simulation presented here can be useful to test the validity of the global fluid dynamics simulations, to study single-particle related aspects such as aging, thermal stresses and chemical stability, to study the distribution of temperature if the particles are not uniform in size, or to study the efficiency in chemical applications.     

Production of R-(+)-α-terpineol by the biotransformation of limonene from orange essential oil,using cassava waste water as medium

The use of two agro-residues (liquid cassava waste and orange essential oil) in the biotransformation of R-(+)-limonene was investigated. The main components of orange essential oil were determined by GC–MS and R-(+)-limonene was shown to be the predominant constituent, accounting for more than 94% of the total content. Cassava wastewater proved to be a suitable substrate for mycelial growth, leading to good, rapid growth with all the fungal strains tested, reaching 29.4 g/l (dry weight) after 3 days of growth (Penicillium sp. 2025). The best R-(+)-α-terpineol yields were achieved when the strains were grown in cassava media and the mycelia then transferred to a new flask containing mineral medium and orange essential oil as the sole C- and energy source. One of the strains tested, Fusarium oxysporum 152B, converted R-(+)-limonene to R-(+)-α-terpineol, yielding nearly 450 mg/l after 3 days of transformation. Growth in the presence of a solution of 1% orange essential oil in decane did not increase the transformation yields.     

Effects of smoking bans on passive smoking exposure at work and at home. The European Community respiratory health survey

This longitudinal study investigated whether smoking bans influence passive smoking at work and/or at home in the same subjects. Passive smoking at work and/or at home was investigated in random population samples (European Community Respiratory Health Survey) in 1990‐1995, with follow‐up interviews in 1998‐2003 and 2010‐2014. National smoking bans were classified as partial (restricted to public workplaces) or global (extended to private workplaces). Multivariable analysis was accomplished by three‐level logistic regression models, where level‐1, level‐2, and level‐3 units were, respectively, questionnaire responses, subjects, and centers. Passive smoking at work was reported by 31.9% in 1990‐1995, 17.5% in 1998‐2003, and 2.5% in 2010‐2014. Concurrently, passive smoking at home decreased from 28.9% to 18.2% and 8.8%. When controlling for sex, age, education, smoking status, and ECHRS wave, the odds of passive smoking at work was markedly reduced after global smoking bans (OR = 0.45, 95% CI 0.25‐0.81), particularly among non‐smokers, while the protective effect of global smoking bans on passive smoking at home was only detected in non‐smokers. Smoking bans both in public and private workplaces were effective in reducing passive smoking at work in Europe. However, given the inefficacy of smoking bans in current smokers’ dwellings, better strategies are needed to avoid smoking indoors.