Effect of Drying Conditions on Microwave Conductivity of Polyaniline

ABSTRACT: Polyaniline was synthesized by using ammonium persulfate initiator in the presence of 1M HC1. It was dried under different drying conditions like room temperature drying (for 48 h), oven drying (at 50-60°C for 8 h under a vacuum), and vacuum drying (at room temperature for 16 h). The conductivities of these samples were measured at microwave frequencies. These samples were also pelletized and the measurements were repeated. The cavity perturbation technique was used for the study.

First Example of Organocatalysis by Polystyrene-Supported PAMAM Dendrimers: Highly Efficient and Reusable Catalyst for Knoevenagel Condensations

This paper describes the first use of polystyrene-supported poly(amidoamine) (PAMAM) dendrimers as heterogeneous basic organocatalysts for carbon–carbon bond formation. Polystyrene-supported PAMAM dendrimers of first, second and third generations have been used as reusable base catalysts in Knoevenagel condensations of carbonyl compounds with active methylene compounds. The reactions proceed in short periods of time and with 100% selectivity. This novel catalyst eliminates the use of aromatic and halogenated solvents, as well as complex purification processes. The catalysts can be recycled ten times.

Investigations on the electrical and structural properties of polyaniline doped with camphor sulphonic acid

Polyaniline is chemically synthesised and doped with camphor sulphonic acid. FTIR studies carried out on these samples indicate that the aromatic rings are retained after polymerisation. The percentage of crystallinity for polyaniline doped with camphor sulphonic acid has been estimated from the X-ray diffraction studies and is around 56% with respect to polyaniline emeraldine base. The change in dielectric permittivity with respect to temperature and frequency is explained on the basis of interfacial polarisation. AC conductivity is evaluated from the observed dielectric permittivity. The values of AC and DC conductivity and activation energy are calculated. The activation energy values suggested that the hopping conduction is the prominent conduction mechanism in this system.

Structural And Surface Morphological Investigation Of Formation Stages Of Highly (002) Oriented Zno Films On Glass Substrates By Spray Pyrolysis Method

ZnO thin films were coated on amorphous glass substrate at various temperatures in the range 160-500 0C by spray pyrolysis method. The as deposited films were characterised by using XRD and SEM. Wurtzite phase of ZnO was formed at a substrate temperature of 400 0C, highly oriented (002) phase was developed with respect to increase of substrate temperature from 450 to 500 0C. Morphological and growth mode of these films were analyzed with respect to structural orientation of films from wurtzite to highly (002) oriented phase. Present study reveals that substrate temperature was one of the important parameters which determine the crystalline quality, population of defects, grain size, orientation and morphology of the films

First results of experimental and theoretical investigations on sextet states of doubly-excited five-electron ions

In continuation of our previous work on doubly-excited ions with three and four electrons we present the first results on optical transitions in the term system of doubly-excited ions with five electrons. Transitions between such sextet states were identified in beam-foil spectra of the ions nitrogen, oxygen and fluorine. Assignments were first established by comparison with Multi-Configuration Dirac-Fock calculations. Later assignments were aided by Multi-Configuration Hartree-Fock calculations (see the contribution by G. Miecznik et al. in this issue). Decay curves were recorded for all six candidate lines. The lifetime results are compared to theoretical values which confirm most of the assignments qualitatively.

Squeezed thermal phonons precurse nonthermal melting of silicon as a function of fluence

A femtosecond-laser pulse can induce ultrafast nonthermal melting of various materials along pathways that are inaccessible under thermodynamic conditions, but it is not known whether there is any structural modification at fluences just below the melting threshold. Here, we show for silicon that in this regime the room-temperature phonons become thermally squeezed, which is a process that has not been reported before in this material. We find that the origin of this effect is the sudden femtosecond-laser-induced softening of interatomic bonds, which can also be described in terms of a modification of the potential energy surface. We further find in ab initio molecular-dynamics simulations on laser-excited potential energy surfaces that the atoms move in the same directions during the first stages of nonthermal melting and thermal phonon squeezing. Our results demonstrate how femtosecond-laser-induced coherent fluctuations precurse complete atomic disordering as a function of fluence. The common underlying bond-softening mechanism indicates that this relation between thermal squeezing and nonthermal melting is not material specific.

Experimentation and Stages of Acquisition for Tobacco Consumption in Spanish Adolescents

One area which has been largely neglected when studying the acquisition of addiction to smoking with the transtheoretical model is whether the individual had previously experimented with smoking. The importance of including the experimentation variable was supported by this research

Development and/or change of the notion of permanent object and operative causality: empirical evidence in the first year of life

This study examines the notion of permanent object during the first year of life, taking into account the controversy of two approaches about the nature of change: developmental change and cognitive change. Using a longitudinal/cross-sectional design, tasks adapted of the subscale of permanent object and operative causality of the Uzgiris-Hunt Scale (Uzgiris and Hunt, 1975) (Uzgiris & Hunt, 1975) were presented to 110 infants of 0, 3, 6 and 9 months-old, which reside in three cities of Colombia. The results showed three types of strategies: (a) Not resolution; (b) Exploratory and (c) Resolution, which follow different trajectories in children’s performance. This allows affirming that adaptive conquests of the cognitive development stay together with the variety of strategies. Using strategies reveals adjustments and transformations of action programs that consolidate the notion of permanent object not necessarily with age, but with self-regulatory processes. Empirical evidence contributes to the understanding of the relations between the emergence of novelty in the development and performance variability

Family Characterization of Young Experimental Consumers of Psychoactive Substances Seen in the Toxicology Department at Colsubsidio

This investigation characterized families of adolescents experimenting with psychoactive substances (PAS) consumption. Materials and methods: For this purpose, a qualitative study with a hermeneutical emphasis was conducted among a population of adolescents between the ages of 12 and 17 who have experimented with PAS. Semi-structured interviews were conducted with patients and their families employing a flexible protocol of 14 categories. Results: The findings showed low levels of family cohesion and sense of family identity, inconsistency between educational patterns followed by the parents, as well as deficient parental support. Similarly, the findings indicate significant peer influence during the first stages of consumption of illegal substances. In this regard, the findings suggest that more than providing physical satisfaction, consumption represents a form of acquiring prestige and social position while granting a sensation of psychological, emotional and social well-being. Conclusions: Parental influence was also found considerable in regarding the consumption of legal PAS, like alcohol and tobacco. The study identified as a high-priority need to promote and incorporate communication and conflict resolution skills within the family dynamics by means of prevention and monitoring programs. Those skills and programs would be aimed at providing parents of adolescents experimenting with PAS consumption with new educational tools to orientate new raising guidelines so as to respond appropriately to the problems identified in this study.

Informal housing in the XXI century. Characteristics of the informal land and housing supply in Bogota during the first decade of the XXI century

This article characterizes the conditions of the informal land and housing supply during the first decade of the xxi century in Bogota, regarding magnitude and location of the informal urban growth (new occupations in the periphery and informal densification of consolidated areas), housing  conditions in recent occupations and the characteristics of the land market. The situation of the  last decade has been reconstructed based in aerial photography analysis, census data quantification  and data analysis from planning and control public entities. Results suggest that due to the relative  land scarcity in Bogotá, among other aspects, the informal market dynamics have experimented changes compared to previous decades, because the growth in consolidated urban areas becomes  more important than the informal urbanization of the peripheries, but at the same time informality  transcends the municipal perimeter to the neighboring municipalities.

Extra activities for the English class in the first cycle of Primary School. 'Actividades extra para la clase de inglés del primer ciclo de Educación Primaria'.

Resumen basado en el de los autores. Trabajo al que se le concedió una ayuda para la creación de materiales curriculares interactivos en el año 2003

Oxford first book of space.

Este recorrido por el universo, lleva a los niños a un viaje alrededor de los planetas, las estrellas, y el más allá. Se analizan los orígenes y la naturaleza de los distintos cuerpos celestes, se explican fenómenos como el agujero negro y los eclipses solares, se repasa la historia de la exploración espacial, y se pondera la posibilidad de vida más allá de la Tierra. Se fomenta la participación en actividades interactivas.

Oxford first book of science.

La primera guía de la ciencia para los niños de seis a ocho años debe abrir sus mentes a ésta y hacerles comprender que es todo lo que hay a su alrededor. Para ello ,se presentan y explican los temas de la ciencia, referidos siempre a experiencias cotidianas que conoce bien el niño. Así, se captura su interés e imaginación, y también, es una forma de dar respuestas para la realización de sus trabajos escolares.