Investigation of the nanocrytalline SnO2 Synthesized by Homogeneous Precipitation

Nanocrystalline tin dioxide synthesized by the homogeneous pre cipitation method using the reaction of tin tetrachloride pentahydrate and urea solutions has been investigated. The nanocrystalline powder has been traced at different calcination temperatures (300ºC-1050ºC), and then characterized by using   Thermogravemetric analysis, differential thermal analysis and x-ray diffraction. The microstructure of the obtained nanoparticles has been examined by scanning and transmission electron microscopy. The average crystallite size, determined by x-ray diffraction, was found to be in the range of 3 –30 nm. The analysis exhibited a tetragonal phase.  Optical properties were investigated by a UV–vis absorption spectrophotometer. The calculated optical band gap lies between 4.47–3.71 eV as a result of increasing the calcination temperatures and crystallite size. Surface area and porosity of SnO2 nanoparticles are measured. Specific surface area which is related to pore volume and decreases from 155 m2/g at 100ºC to 3.3 m2/g at 1050ºC.Â

Statistical analysis for the impact of smoking on the behavior and health of Qatari adolescents

The links between the use of tobacco and health risks are well known. Most of the younger smokers reside in Asia which includes Qatar, the focus country of this study. Cigarette smoking among children is rising at an alarming rate worldwide including Qatar. As youth make up a significant percentage of the population and to achieve the health objectives of the Qatar Vision 2030, it is essential to ensure the health and well-being of adolescents, as they are the future of Qatar. This study focuses on exploring the patterns of tobacco use and its impacts on the adolescents by conducting a survey in different schools across Qatar. The questionnaire was administered in five schools, selected by proportional random sampling. The responses were recorded from the sample for general questions regarding interest in physical activities, relationship with family and friends, mental satisfaction, health, academics and access to cigarettes. 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.Scopu

Optimirana i validirana protočna injekcijska spektrofotometrijska analiza topiramata, piracetama i levetiracetama u farmaceutskim pripravcima

Application of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction with ortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels. Also, the method has been optimized and fully validated in terms of linearity and range, limit of detection and quantitation, precision, selectivity and accuracy. The method was successfully applied to the analysis of pharmaceutical preparations.Opisana je osjetljiva i brza protočna injekcijska analiza (FIA) za određivanje topiramata, piracetama i levetiracetama u farmaceutskim pripravcima. Metoda se temelji na reakciji ortho-ftalaldehida i 2-merkaptoetanola u bazičnom puferu i mjerenju apsorbancije na 295 nm u protočnim uvjetima. U svrhu povećanja osjetljivosti i dobivanja reproducibilnih rezultata optimirane su varijable koje utječu na određivanje kao što su volumen injektiranog uzorka, pH, ionska jakost, koncentracija reagensa, brzina protoka reagensa i drugi FIA parametri koristeći četvrt-frakcijski faktorijalni dizajn, za pet faktora na dva nivoa. Metoda je optimirana i potpuno validirana (linearnost, područje određivanja, granica detekcije i kvantifikacije, preciznost, selektivnost i točnost). Metoda je uspješno primijenjena za analizu farmaceutskih pripravaka

Calculation of electric stresses in three-core belted cables

The authors present a combined method based on inversion and charge-simulation techniques for calculating the electric field in three-core belted cables. Numerical techniques have been developed based on the charge-representation, charge-simulation and successive-imaging methods. The set of equations which describe the potential and field is solved only once with direct determination of the electric potential and field values at any time instant. This achieved higher accuracy with a very large saving in computer time in comparison with previous method

Induced voltages on fence wires and pipelines by AC powertransmission lines

A method is developed for calculating the induced voltages on fence wires/pipelines underneath AC power transmission lines. The method is based on the charge simulation technique and takes into account the disturbances of the electric field and potential due to the presence of the fence wire/pipeline underneath the line. The calculated values of the induced voltage on fence wires are compared with those measured before. Induced voltages on pipelines underneath 230- and 380-kV lines are measured, correlated to the calculated values and discussed in the light of electric field induction on objects adjacent to AC power transmission line