Modelling and performance of a small siphonic hydropower system

A siphon turbine is a low-head, axial-flow hydropower device that can be installed across an impound structure, such as a weir. A laboratory-scale siphon turbine and generator system is built from both off-the-shelf components and bespoke components designed using well-documented guidance. This paper proposes a modelling method for the system, which allows performance to be assessed as a function of operating variables including head, electric load, runner speed and flow rate. An un-modified, commercially available propeller is used for the runner, whose blade geometry is defined within the model as a set of polynomials. This enables flow angles at any radial position on a blade to be determined as a function of the system operating point. Consequently, the impact of design changes on system performance can be quantified, such as part-load efficiency for example. Testing using the laboratory-scale system is conducted up to a maximum gross head of 0.25 m, to validate the component models and then to demonstrate that the final system model provides satisfactory agreement with experiments over the operational speed and head range. The model therefore permits rapid conceptual design to be carried out without the need for computationally intensive co-optimisation of components.     

A voltage controlled CMOS current divider with linear characteristic

A compact voltage controlled CMOS current divider is presented. Differently from previous implementations, exploiting the MOSFET translinear characteristics in subthreshold region, the proposed circuit is based on devices operating from moderate to strong inversion. An input current linearity range of nearly a decade is obtained by compensating for the deviations from the ideal drain current square-law approximation through an original empirical approach. The circuit is suitable for use as a building block in analog multipliers and for transconductor continuous tuning. The effectiveness of the proposed configuration is demonstrated by means of electrical simulations, performed on a prototype designed with a commercial process. The robustness of the linearization algorithm with respect to temperature variations is proven.     

Bio-ethanol production by fermentation of ricotta cheese whey as an effective alternative non-vegetable source

The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (“Scotta”), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13 h) and with the highest ethanol yield (97% of the theoretical value).     

A.c.-impedance spectroscopy study of oxygen reduction at Nafion® coated gas-diffusion electrodes in sulphuric acid: Teflon loading and methanol cross-over effects

The kinetics of oxygen reduction have been studied at Nafion®-coated dual layer gas-diffusion electrodes at 60 °C in 2.5 M H₂SO₄. A.c. impedance and steady state galvanostatic measurements have been carried out on electrodes containing various PTFE loadings. A.c. impedance spectroscopy supplied information on charge transfer resistance, series resistance and double layer capacitance of electrodes during the oxygen reduction process. These parameters, together with those derived by d.c. measurements (i.e. Tafel slopes, charge transfer coefficient, etc.), allowed a better identification of the features governing the electrode efficiency and the reduction mechanism. The best electrode was found to be one containing 30% PTFE; this showed both the lowest charge transfer resistance and the lowest overpotential for oxygen reduction. This electrode also showed lower overpotential than the same uncoated electrode at low current densities. The poisoning effect by methanol has been also investigated. Upon addition of methanol to the solution, no change was observed in the reaction mechanism at low overpotentials. In contrast, a significant variation of the Tafel slope was observed at high overpotentials. This behaviour is interpreted in terms of the variation of Pt-O bond strength as a function of electrode potential.     

The impact of related variety on the creative employment growth

Cultural and creative industries (CCIs) have recently become highly relevant with regard to creative economy research, as they are considered drivers of regional and urban innovation policies and economic growth. CCIs are a priority sector on the European agenda and represent an excellent opportunity to exit the current economic crisis. In the literature, the most discussed aspect of CCIs is their value creation ability, which is due to a high degree of diversity/variety, and their impact on innovation within the wider economy, which results from the activation of cross-fertilisation processes between different sectors. Evolutionary economic geography (EEG), adopting the recently established approach based on related variety, also emphasises the issues of diversity/variety as determinants of local and urban development and innovation. This interesting and complex theoretical framework has produced a considerable number of empirical studies, none of which has been specifically applied to the creative sector. With the present study, we intended to contribute to the debate on creative economy research and EEG by investigating the impact of variety in CCIs in Italy, following the related-variety approach and using a long-term employment perspective (1991–2011). The results indicated that related variety has an important effect on the growth of creative industries, characterised by high internal connections between different creative activities. Our outcomes also led us to reassess the view held by some, namely, that creative industries can actually make a strong impact on economic growth in the wider economy; this did not appear to emerge in the Italian context, according to the methodologies we used.     

The serotonin transporter 5-HTTLPR polymorphism and treatment response to nicotine patch: follow-up of a randomized controlled trial.

In this follow-up of a randomized placebo-controlled clinical trial of nicotine replacement transdermal patch for smoking cessation, 741 smokers of European ancestry who were randomized to receive active patch or placebo patch were genotyped for the serotonin transporter gene-linked polymorphic region. The study setting was a primary care research network in Oxfordshire, United Kingdom. The primary outcome measures were biochemically verified sustained abstinence from cigarette smoking at end of treatment and 24-week follow-up. The main effect of genotype was not associated with sustained abstinence from smoking at either end of treatment (SL: p=.33; SS: p=.81) or 24-week follow-up (SL: p=.05; SS: p=.21), and we found no evidence for a genotypextreatment interaction effect. In summary, despite the theoretically important contribution of serotonin neurotransmission to smoking cessation, the serotonin transporter gene was not associated with treatment response to nicotine patch for smoking cessation in this primary care-based trial.     

Characterization of major and trace minerals,fatty acid composition,and cholesterol content of Protected Designation of Origin cheeses

Cheese provides essential nutrients for human nutrition and health, such as minerals and fatty acids (FA). Its composition varies according to milk origin (e.g., species and breed), rearing conditions (e.g., feeding and management), and cheese-making technology (e.g., coagulation process, addition of salt, ripening period). In recent years, cheese production has increased worldwide. Italy is one of the main producers and exporters of cheese. This study aimed to describe mineral, FA, and cholesterol content of 133 samples from 18 commercial cheeses from 4 dairy species (buffalo, cow, goat, and sheep) and from 3 classes of moisture content (hard, <35% moisture; semi-hard, 35–45%; and soft, >45%). Mineral concentrations of cheese samples were determined by inductively coupled plasma optical emission spectrometry, and FA and cholesterol contents were determined by gas chromatography. Moisture and species had a significant effect on almost all traits: the highest levels of Na, Ca, and Fe were found in cheeses made from sheep milk; the greatest level of Cu was found in cow milk cheese, the lowest amount of K was found in buffalo milk cheese, and the lowest amount of Zn was found in goat cheeses. In all samples, Cr and Pb were not detected (below the level of detection). In general, total fat, protein, and minerals significantly increased when the moisture decreased. Buffalo and goat cheeses had the highest saturated FA content, and sheep cheeses showed the highest content of unsaturated and polyunsaturated FA, conjugated linoleic acid, and n-3 FA. Goat and sheep cheeses achieved higher proportions of minor FA than did cow and buffalo cheeses. Buffalo cheese exhibited the lowest cholesterol level. Our results confirm that cheese mineral content is mainly affected by the cheese-making process, whereas FA profile mainly reflects the FA composition of the source milk. This study allowed the characterization of mineral and FA composition and cholesterol content and revealed large variability among different commercial cheeses.     

Inhibition of soybean lipoxygenase-1 by chain-breaking antioxidants

The aim of this investigation was to determine whether chain-breaking antioxidants able to prevent lipid peroxidation can inhibit lipoxygenase-1 (EC 1.13.11.12). Therefore, the effects of ascorbic acid, 6-palmitoylascorbic acid and trolox on the enzyme activity were analyzed by means of Lineweaver-Burk double reciprocal plots and Yoshino's graphical method. The effect of these compounds on the formation of free radicals during lipoxygenase-1 reaction was investigated as well, by monitoring the enzymic formation of oxodienes. We present evidence that the chain-breaking antioxidants ascorbic acid, 6-palmitoylascorbic acid and trolox inhibit soybean lipoxygenase-1 in the micromolar concentration range (Ki 27, 3 and 18 μM, respectively). The inhibition is competitive, complete and reversible. All three compounds trap the free radicals formed during the lipoxygenase-catalyzed reaction, which might substantially contribute to their inhibitory ability. These findings can have physiological significance in the light of the lipoxygenase involvement in biomembrane remodelling.