Enhanced properties for visible-light-driven photocatalysis of Ag nanoparticle modified Bi2MoO6 nanoplates

The visible light driven Bi₂MoO₆ photocatalyst doped with different contents of Ag nanoparticles was successfully synthesized by a combination of hydrothermal and sonochemical methods. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM and TEM) and UV–visible spectroscopy to investigate crystalline structure, morphology, composition and photocatalytic properties. XRD patterns and TEM images of the samples revealed pure phase orthorhombic Bi₂MoO₆ nanoplates without any detection of Ag dopant due to its low concentration and very tiny particle size. TEM images showed that Ag nanoparticles with the size of 10–15 nm were dispersed randomly on the surface of Bi₂MoO₆. The XPS analysis of Ag/Bi₂MoO₆ nanocomposites revealed the presence of additional metallic Ag. Photocatalytic activities of the Ag/Bi₂MoO₆ nanocomposites were evaluated by determining the degradation of rhodamine B (RhB) under visible light radiation. In this research, the 10 wt% Ag/Bi₂MoO₆ nanocomposites showed the best photocatalytic activity. The results suggest that the dispersion of Ag nanoparticles on the surface of Bi₂MoO₆ significantly enhances its photocatalytic activity.     

Survey of domestic food purchases and related home handling practices in the Abruzzo region (central Italy): Data collection and analysis through a language-independent classification system

A telephone survey was carried out on 13,486 randomly selected households located in the Abruzzo region (central Italy). Three questionnaires were specifically designed in relation to three different groups of foods (Meat and meat products, Fishery products, Fruit and vegetables). Questions were mainly focused on the amount and number of purchases, type of retailer, and home food handling practices with respect to the week prior to the interview. Data were classified according to a multilingual thesaurus system (LanguaL). Results allowed to estimate domestic purchases (in kg) per capita for different food categories. The category “Red meat/Cattle” accounted for a large part of purchases in the “meat and meat products” group (10.9 kg per capita/year; 32.2% of purchases in the group) while the category “Fish or related organism/Fish” was the most purchased in the “fishery products” group (6.9 kg per capita/year; 63.3%). The aggregation of more detailed characteristics enabled the identification of popular categories of foods, such as “Red meat/Cattle/Divided into pieces” (25% of the “meat and meat products” group). Significant differences (p < 0.05) were found between the four different provinces (L'Aquila, Chieti, Pescara and Teramo) with respect to “Poultry/Chicken” and “Red meat/Cattle” categories. Householders were also asked about post-purchase food handling practices that might be hazardous to food safety. More than 20% of those surveyed stated that they thawed frozen meat at room temperature. The degree of doneness after cooking of different food categories was generally high: over 90% of products purchased in the majority of meat and fish categories were properly cooked. However a noticeable proportion of householders (about 15%) reported medium or rare cooking of “Red meat/Cattle” and “Red meat/Swine”. Differences (p < 0.05) were also found between consumers of different ages, with people over 65 years old being more prone to freeze meat and cook it thoroughly.The survey was carried out in a specific geographic area and on a statistically significant sample of households, thus allowing a collection of data on domestic habits relating to food purchases and home food handling practices. This information should be included in the framework of quantitative microbial risk assessment (QMRA) models as a measure of the actual exposure of consumers to pathogenic microorganism. The LanguaL system also proved to be a practical language-independent method useful not only to identify and describe food items but also to classify them according to specific food safety characteristics.     

Chemistry of the pyrrolo[1,2-alpha]benzimidazole antitumor agents: influence of the 7-substituent on the ability to alkylate DNA and inhibit topoisomerase II

This study addresses the influence the 7-substituent on the cytotoxicity of pyrrolo[1,2-alpha]-benzimidazole quinones possessing a 6-aziridinyl group (PBIs) and a 6-acetamido group (APBIs). Reduction of a PBI to the aziridinyl hydroquinone results in both nucleophile trapping (alkylation) and 1,5-sigmatropic shift reactions. The latter process is essentially an internal redox reaction wherein the hydroquinone causes reductive opening of the aziridinyl ring. The 7-substituent controls the fate of the aziridinyl ring by means of steric and electronic effects. An electron-rich 7-substituent favors the 1,5-sigmatropic shift reaction. If the 7-substituent distorts the 6-aziridinyl group from the conformation required for the 1,5-sigmatropic shift, then nucleophile trapping occurs. The 7-methyl substituent results in significant nucleophilic trapping, and the 7-unsubstituted and 7-methoxy substituents favor the 1,5-sigmatropic reaction. Thus, the 7-methyl PBIs show the most cytotoxicity of the analogues studied. The APBIs are cytotoxic only as quinones, and reduction to the hydroquinone results in loss of activity. Consistent with this observation, the change from 7-methyl to the more electron-rich 7-methoxy results in a substantial loss of APBI cytotoxicity as well as decreased topoisomerase II inhibition. The mechanism of inhibition is thought to involve the interacalation of only electron deficient APBIs into DNA.     

“Metallisation” of oxide surfaces observed by in situ high-resolution electron microscopy

Intense irradiation (25–40 A/cm²) at intermediate energy (400 keV) has been found to cause “metallisation” of tungsten oxide and titanium niobate crystal surfaces. The possible mechanisms and the likely consequences for high-resolution imaging of clean oxide surfaces are briefly discussed.     

Interactions of electron beams with surfaces of MgO crystals

The strong interaction of electrons with the flat surfaces of small crystals has been investigated by high resolution CTEM and STEM instruments. When cubic crystals of MgO smoke with edges 20–300 nm are oriented so that the ?001? or ?011? zone axis is parallel to the optical axis, then two kinds of external fringes are observed at (100) surfaces. One kind is parallel to the surface, having spacings up to 0.4 nm. These are caused by interference among the electron channelled along the surface. Fresnel-diffracted ones and the remnant of the incident beam. Fringes of the other kind, which appear as fine structure in the first kind of fringes, are perpendicular to the crystal edge. When an electron beam is parallel to the ?011? axis, the second kind of fringe, whose spacing is 0.3 nm corresponding to d₀₁₁, shows the difference of the surface potential between magnesium atoms and oxygen atoms. Selected area diffraction patterns and microdiffraction patterns also show the same periodicities as in the two kinds of fringes. Simulated images, using the scattering amplitudes for ions, are compared with observations.     

Fast Full-Band Device Simulator for Wurtzite and Zincblende GaN MESFET Using a Cellular Monte Carlo Method

A fast full-band device simulator for wurtzite and zincblende GaN using a Cellular Monte Carlo (CMC) approach is reported for wurtzite and zincblende GaN. The full-phonon dispersion relationship including anisotropic polar-optical phonon scattering is taken into account for the wurtzite GaN calculation. In the bulk simulation, the CMC model is about 30–100 times faster than the conventional Ensemble Monte Carlo model at high electric field region. This CMC model is applied to the simulator of MESFET devices, and the calculation speed is significantly improved.     

Analytical simulation of tensile response of fabric reinforced cement based composites

A model simulating the tensile behavior of fabric–cement composites is presented to relate the properties of the matrix, fabric, interface and the damage parameters to the overall mechanical response of the composites. Crack spacing parameters measured during tensile tests are used to define the damage parameters, and related to the stiffness degradation as a function of the applied strain. This procedure is integrated in composite laminate theory using an incremental approach to model the uniaxial tensile response. Two approaches of linear and nonlinear fabric bridging models are used. The model is capable of using interface parameters for different fabrics, matrix properties, and processing parameters. Simulation results are studied by means of parametric simulation and a validation of a variety of experimental observations which vary the matrix formulation with flyash, changes in pressure after casting, and fabric type.     

Potential applications of phase change materials in concrete technology

In internal curing, pre-wetted lightweight aggregates (LWA) serve as internal reservoirs to supply the extra water needed by the cementitious and pozzolanic components of the concrete during their hydration processes. Due to their porous nature and reasonably high absorption capacity, the LWA can also be filled with other materials, such as phase change materials (PCMs). In this paper, three potential applications of PCM-filled LWA in concrete technology are presented. In addition to the previously explored application of increasing the energy storage capacity of concrete in residential and commercial construction by using a PCM with a transition temperature near room temperature, applications for higher and lower temperature PCMs also exist. In the former case, a PCM can be used to reduce the temperature rise (and subsequent rate of temperature decrease) of a large concrete section during (semi)adiabatic curing, to minimize thermal cracking, etc. In the latter case, a PCM can perhaps reduce the number or intensity of freeze/thaw cycles experienced by a bridge deck or other concrete exposed to a winter environment. In this paper, these latter two applications are preliminarily explored from both experimental and modeling viewpoints.