Proton Conduction in Dense and Porous Nanocrystalline Ceria Thin Films

The electrical conductivity of ceria thin films (epitaxial as well as dense and porous nanocrystalline) is investigated in dry and wet atmosphere at temperatures below 500 °C. For the epitaxial and the fully dense nanocrystalline samples, no significant differences can be observed between dry and wet conditions. In marked contrast, the nanocrystalline porous films obtained via spin coating exhibit a considerable enhancement of the protonic conductivity below 300 °C in wet atmosphere. This outcome reveals that the residual open mesoporosity plays the key role for the enhancement of the proton transport at low temperatures and not the high density of grain boundaries. The quantitative analysis of the various pathways, along which the proton transport can take place, indicates that the observed proton conduction can arise not only from bulk water adsorbed in the open pores but also from the space charge zones on the water side of the water/oxide interface.     

Effects of nutrient supplementation on fermentation kinetics, H2S evolution, and aroma profile in Verdicchio DOC wine production

Different yeast nutrient additions were studied for the 2008 and 2009 vintages of Verdicchio grape juice fermentation. Addition of yeast derivatives at the beginning of fermentation and/or different amounts of diammonium phosphate at various times within the first half of fermentation were examined, with initial yeast assimilable nitrogen concentrations set at 200 and 250 mg l^?1. Supplementation with glutathione in combination with this nitrogen addition was also evaluated. Fermentation rates were monitored throughout these fermentations carried out under different nutrient conditions. H₂S production during fermentation and synthesis of volatile compounds in the finished wines were quantified; the wines also underwent sensory evaluation. The fermentation kinetics were almost exclusively influenced by the inorganic nitrogen supplementation with diammonium phosphate. H₂S evolution was more affected by assimilable nitrogen than glutathione. Diammonium phosphate significantly reduced H₂S production, with a further reduction in the presence of yeast derivative. This nitrogen supplementation yielded higher concentrations of acetate esters, and in particular of isoamyl acetate (fruity aromas), which positively influences the analytical and aroma profile of wines and results in a general reduction in 2-phenylethanol production (floral aromas). Overall results (two harvesting times and vintages) indicate that the management with diammonium phosphate and yeast derivative supplementation improves the kinetics of fermentation and provides a good tool to reduce H₂S formation and increase the analytical and sensory quality of Verdicchio wine.     

High-Frequency Induction Hardening with Controlled Capacitors-Discharge Pulse-Operation Processes

Induction hardening processes with power pulses obtained by means of capacitors-discharge high-frequency generators are discussed. The process is characterized by high-power densities and heating times on the order of some tens or hundreds of milliseconds together with cooling rates obtained by self-quenching without the use of auxiliary means. The possibility of obtaining the most favorable transient temperature distribution in the workpieces by controlling the shape of the pulses and therefore the variable time rate energy supply is examined. The influence of shape of pulses and discharge circuit's electrical parameters on the heating and cooling transients has been analyzed by a thermal model which allows prediction of the depths of hardening. Measurements from hardening tests carried out on steel samples varying the pulse shapes are given in support of the calculation results.     

A Function Point-Like Measure for Object-Oriented Software

We present a method for estimating the size, and consequently effort and duration, of object oriented software development projects. Different estimates may be made in different phases of the development process, according to the available information. We define an adaptation of traditional function points, called Object Oriented Function Points, to enable the measurement of object oriented analysis and design specifications. Tools have been constructed to automate the counting method. The novel aspect of our method is its flexibility. An organization can experiment with different counting policies, to find the most accurate predictors of size, effort, etc. in its environment. The method and preliminary results of its application in an industrial environment are presented and discussed.     

Hypomethylation in cervical tissue: is there a correlation with folate status?

5-Aminolevulinic acid (ALA) is the first intermediate substrate in the heme synthetic pathway and is the substrate of aminolevulinic acid dehydratase (ALAD, porphobilinogen synthase). Because lead effectively inhibits ALAD activity, resulting in accumulation of ALA in urine and blood, urinary ALA (ALAU) has been used as a biomarker for lead exposure or early biologic effect of lead. Intraindividual variation in urinary excretion of ALA requires the use of 24-hour urine samples or adjustment of single urine samples by other normalizing variables, such as urinary creatinine concentration. Previous studies of ALAU concentration have used various adjustment methods; however, few have compared creatinine-adjusted ALAU concentration with ALA concentration in plasma (ALAP) from subjects with low (< 30 micrograms/dL) to moderate (< 60 micrograms/dL) levels of blood lead. To determine if creatinine-adjusted ALAU is associated with ALAP, we measured ALAU, ALAP, and urinary creatinine in 65 Korean lead workers with blood lead concentrations in the range of 14-60 micrograms/dL. ALAU, ALAU/creatinine, or ALAU/log creatinine all correlated with ALAP. However, ALAU/creatinine correlated more closely with ALAP based on Spearman's r (rs = 0.40, P, = 0.0009), supporting the use of ALA/creatinine in single urine samples as a surrogate for ALAP.     

Optical and morphological properties of InGaAs/AIGaAs self-assembled quantum dot nanostructures for 980 nm room temperature emission

This work deals with the study of optical and morphological properties of InGaAs/AlGaAs quantum dot （QD） structures grown by molecular beam epitaxy （MBE）. Photoluminescence （PL） emission energies, activation energies of PL quenching and QD sizes are studied as functions of the Al content in the AlyGal-yAs confining layers （CL）. We show that the PL emission energy of In（Ga）As/AlyGal-yAs QD structures increases with increasing y and that the sizes of InAs/AlyGal-yAs QDs decrease with increasing y. By the comparison of the experimental results with those of an effective-mass model developed to calculate the QD fundamental transition energies, we show that the blueshift of emission energy has to be ascribed not only to the increase in barrier discontinuities that confine the carriers into QDs but even to effects related to changes of the QD morphology dependent on CL composition. Moreover, we show that the Al content in the barriers determines also the activation energy of thermal quenching of PL, which depends on the thermal escape of carriers from QD levels. These studies resulted in the preparation of structures with efficient light-emission in the 980 nm spectral window of interest for lightwave communications.     

On the stabilization performance of some hybrid controls

Recently, significant interest has been raised in the study of hybrid systems. In this paper we analyse the performance of some hybrid controls to stabilize a model problem, comparing it with classical methods. We used computer simulations as well as analytic arguments which revealed the presence of periodic orbits for the considered hybrid dynamics. Existence and stability of the latter have also been considered in the framework of a single dynamical system on a suitable manifold (indeed, a stratified set), called the hybrid manifold.     

Modeling Steady Acoustic Fields Bounded in Cavities with Geometrical Imperfections

A mathematical method is derived within the framework of classical Lagrangian field theory, which is suitable for the determination of the eigenstates of acoustic resonators of nearly spherical shape. The method is based on the expansion of the Helmholtz differential operator and the boundary condition in a power series of a small geometrical perturbation parameter e{\epsilon} . The method extends to orders higher than e²{\epsilon^2} the calculation of the perturbed acoustic eigenvalues, which was previously limited by the use of variational formalism and the methods of Morse and Ingard. A specific example is worked out for radial modes of a prolate spheroid, with the frequency perturbation calculated to order e³{\epsilon^3} . A possible strategy to tackle the problem of calculating the acoustic eigenvalues for cavities presenting non-smooth geometrical imperfections is also described.     

Solid–Liquid Equilibria for the CO<Subscript>2</Subscript> + R23 and N<Subscript>2</Subscript>O + R23 Systems

A recently built experimental setup was employed for the estimation of the solid–liquid equilibria of alternative refrigerant systems. In this paper two binaries, i.e., carbon dioxide + trifluoromethane (CO₂ + R23) and nitrous oxide + trifluoromethane (N₂O + R23), were studied down to temperatures of 117 K. In order to check the reliability of the apparatus, the triple points of the pure fluids contained in the mixture were measured, revealing good consistency with the literature. The results obtained for the mixtures were interpreted by means of the Schröder equation.