Increasing the photocatalytic and fungicide activities of Ag3PO4 microcrystals under visible-light irradiation

The present study reports for the first time the performance of silver phosphate (Ag₃PO₄) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag₃PO₄ microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag₃PO₄ have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag₃PO₄ were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag₃PO₄ was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation.     

High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis

The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose.     

Handling causality and schedulability when designing and prototyping cyber-physical systems

Software and Systems Modeling - Cyber physical systems are built upon digital and analog circuits, making it necessary to handle different models of computation during their design and verification...     

3He in 99.5% Porous Aerogel at the Normal-Superfluid Transition

We have used a torsional oscillator to measure the superfluid density and dissipation near the superfluid transition of ³ He in aerogel of 99.5% porosity. We used a new cell (constructed at Penn State) for which the aerogel was grown in the pores of a 100 m silver sinter. The cell was tested with ⁴ He and showed no signs of the second-sound resonances that have interfered with previous torsional oscillator measurements. The measurements with ³ He, presented here, were taken at pressures of 1.34 and 4.13 bars. We observed values of _s / in the T 0 limit of 0.05 and 0.14 respectively. Our measurements show an increase in the dissipation on warming through T _c . This series of measurements is ongoing and temperature sweeps at various pressures are planned.     

3He in Aerogel – an Inhomogeneously Disordered Unconventional Superfluid

We have examined the superfluidity of ³ He in 98.2% porous silica aerogel with up to 34% ⁴ He at 21.6 bar. The mixture is phase-separated for ⁴ He fractions between 11% and 34%. The ⁴ He-rich, phase preferentially occupies the regions of highest silica density in the aerogel, thus modifying the distribution of the correlated disorder seen by superftuid ³ He. The ³ He T _c increases slightly with ⁴ He content while the superfluid fraction decreases rapidly. This behavior is inconsistent with that of ³ He in a homogeneously scattering medium and is analogous to that of a granular superconductor.     

Influence of heat-treatment environment on Ni-ferrite nanoparticle formation from coconut water precursor

The kinetics of formation of NiFe₂O₄ nanoparticles were investigated where the nanoparticles were produced by the proteic-sol–gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe₂O₄ nanoparticles in a superparamagnetic state as determined from Mössbauer spectroscopy. In general, heat treatment at high temperature leads to a nanocomposite rich in NiFe₂O₄. In air, annealing at 1173 K for 8 h favored the formation of the magnetically ordered NiFe₂O₄ inverse spinel structure, with bulk characteristics and average crystal sizes of approximately 66 nm. In a nitrogen atmosphere and in compacted BN powder under air atmosphere, the NiFe₂O₄ spinel structure stabilized for temperatures up to 873 and 773 K, respectively, however, decomposition of the NiFe₂O₄ phase into other undesired structures was observed above 873 K.     

Regional characteristics and the decision to innovate in a developing country: A multilevel analysis of Ecuadorian firms

This is the first study that uses multilevel modelling to analyse regional influence on the decision to invest in innovation activities of firms in a single developing country, Ecuador. Our results indicate that the decision to invest in R&D and in other innovation activities are conditioned by the region in which the firm is located. Regional loan volume, orientation towards knowledge exploitation and intra-regional-sectorial R&D spillovers are positively associated with both types of innovation activities, while regional levels of co-operation and inter-regional R&D spillovers are only positively associated with the probability of investing in other innovation activities.