Mössbauer Spectroscopic Study of a Mural Painting from Morgadal Grande,Mexico

Hyperfine Interactions - In this study, 57Fe Mössbauer spectroscopy has been applied to fragments of a mural painting excavated at Morgadal Grande, Mexico, to characterize the pigments used. A...     

Encouraging Young Women to Stay in the Mathematics Pipeline: Mathematics Camps for Young Women

For two summers, week‐long residential mathematics programs were held for high school women, with the primary goal of encouraging them to continue their study of mathematics. The activities were designed to rekindle their excitement about mathematics and to support the idea that women should learn advanced mathematics. This paper reports the findings of the data collected to assess the programs. Statistically significant changes were found in student attitudes, confidence level, willingness to continue working on a problem, and perception of the value of group work. Journal entries confirmed the statistical analysis. Follow‐up surveys also indicated that the summer programs changed the way the participants perceived mathematics and mathematics courses.     

Thermal representation of the energy density in bounded spaces

The energy-momentum tensor of a quantum massless free field in a curved spacetime can be written in many cases as an integral with a thermal denominator and a modified phase-space numerator. It is shown that in general the thermal denominator is related to the bounded nature of the system, which in turn implies a representation of the energy density as an infinite numerable sum in Fock space. The modification of the phase-space density is related to the absence of long-wave contributions for nonzero values of the spin.     

Metropolitan Optical Networks: When to Change to DWDM

In this article we propose a new methodology to estimate the change in the bandwidth demand in time, mainly in residential areas. The bandwidth demand forecast is a basic aspect to decide the evolution of metropolitan optical networks. The word evolution refers to the necessity of making changes in networks, either by upgrading or replacing different elements that are part of the network. This analysis, along with a technological alternatives analysis, provides the operator the needed information to achieve the appropriate network planning and to make investment decisions.     

Nutritional composition,antioxidant activity and isolation of scopoletin from Senecio nutans: support of ancestral and new uses

Continuing with our study characterising Senecio nutans Sch. Bip., we have isolated and identified a simple coumarin, scopoletin, that could be relevant for the biological properties of the species related with the ancestral medical uses. This is the first report of scopoletin from S. nutans. In addition, the extract was analysed for its antioxidant activity using the ABTS and FRAP method as well as providing the first nutritional analyses of this plant from northern Chile highlands.     

A new quality control material for marine environmental analysis

The implementation of the European Water Framework Directive (WFD) and of the sediment-quality criteria related to the potential disposal of dredged materials is expected to involve a substantial increase in the number of chemical analyses performed in marine environmental control laboratories. The chemical characterization of sediments (metals, elemental composition, etc.) and the potential release of metals under changing environmental conditions are relevant when dealing with risk assessment. The present paper describes the preparation of a quality control material (QCM) harbor sediment carried out in a specifically equipped laboratory at the University of Barcelona. The results of homogeneity and stability studies for total metal content (Cd, Cr, Cu, Ni, Pb, and Zn), extractable metal following the BCR three-step sequential extraction procedure (BCR-SEP), and total carbon content show the suitability of QCM for multi-parameter routine quality control (QC) in marine environmental laboratories.     

Synthesis of heterocyclic compounds. XXXIX. Synthesis of 5-cyano-2-phenyl-4-thioxo-3,4-dihydropyrimidines

The reaction of thiobenzamide with 3-alkoxy-3-aryl(or alkyl)-2-cyanopropenenitriles 1 and sodium 2-propoxide in 2-propanol afforded after acidic treatment 6-aryl(or alkyl)-5-cyano-2-phenyl-4-thioxo-3,4-dihydropyrimidines 3 through formation of the 3-aryl(or alkyl)-2-cyano-3-thiobenzamidopropenenitrile 2 that has been isolated in one case ( 2a , R¹ = Ph).     

Bismuth colloids and films from non-aqueous solvents

Bismuth colloids and metal-metal oxide films have been prepared by the method Chemical Liquid Deposition (CLD). The metal is evaporated to yield atoms which are solvated at liquid nitrogen temperature, and upon warming stable liquid colloids, are formed with particle size ranging between 50–350 Å. Zeta potentials were calculated according to the convention of Hunter and the Hückel equation, for most of these negatively charged particles. Upon solvent removal, colloidal particles coalesce to form films, which contain some residual solvent. The synthesis of colloids and films from Bi with acetone, 2-butanone, 4-methyl-2-pentanone, ethanol, 2-propanol, DMF, THF, DMSO, benzene and toluene is reported. Transmission Electron Microscopy (TEM) allows us to determine particle size. FTIR, Thermogravimetric Analyses (TGA) and Scanning Electron Microscopy (SEM) have aided in film characterization. These studies indicate that solvents are incorporated into the films. Resistivity studies showed that they behave as semiconductors rather than pure metals. TGA studies reveal that loss of weight occurs within 244–453°C. The films are very stable with 5–30% weight loss at 550°C.     

Hybrid Nanobioengineered Nanomaterial-Based Electrochemical Biosensors

Nanoengineering biosensors have become more precise and sophisticated, raising the demand for highly sensitive architectures to monitor target analytes at extremely low concentrations often required, for example, for biomedical applications. We review recent advances in functional nanomaterials, mainly based on novel organic-inorganic hybrids with enhanced electro-physicochemical properties toward fulfilling this need. In this context, this review classifies some recently engineered organic-inorganic metallic-, silicon-, carbonaceous-, and polymeric-nanomaterials and describes their structural properties and features when incorporated into biosensing systems. It further shows the latest advances in ultrasensitive electrochemical biosensors engineered from such innovative nanomaterials highlighting their advantages concerning the concomitant constituents acting alone, fulfilling the gap from other reviews in the literature. Finally, it mentioned the limitations and opportunities of hybrid nanomaterials from the point of view of current nanotechnology and future considerations for advancing their use in enhanced electrochemical platforms.