Application of SCTA methods for kinetic analysis of solid state reactions and synthesis of materials

Journal of Thermal Analysis and Calorimetry -     

A note on travelling-wave solutions to Lax’s seventh-order KdV equation

Ganji and Abdollahzadeh [D.D. Ganji, M. Abdollahzadeh, Appl. Math. Comput. 206 (2008) 438–444] derived three supposedly new travelling-wave solutions to Lax’s seventh-order KdV equation. Each solution was obtained by a different method. It is shown that any two of the solutions may be obtained trivially from the remaining solution. Furthermore it is noted that one of the solutions has been known for many years.     

THE REACTIONS OF N3P3CL6 WITH POLYFUNCTIONAL REAGENTS

Abstract

The reactions of N₃P₃Cl₆ with polyfunctional reagents, such as glycerol, are reported. NMR spectroscopic and X-ray crystallographic studies will be presented.     

Detection of trace concentrations of helium and argon in gas mixtures by laser-induced breakdown spectroscopy

We report what we believe to be the first demonstration of the detection of trace quantities of helium and argon in binary and ternary gas mixtures with nitrogen by laser-induced breakdown spectroscopy (LIBS). Although significant quenching of helium transitions due to collisional deactivation of excited species was observed, it was found that losses in analytical sensitivity could be minimized by increasing the laser irradiance and decreasing the pressure at which the analyses were performed. In consequence, limits of detection of parts-per-million and tens of parts-per-million and linear dynamic ranges of several orders of magnitude in analyte concentration were obtained. The results of this study suggest that LIBS may have potential applications in the detection of other noble gases at trace concentrations.     

Measurements of thermal electron attachment rate coefficients to molecules using an electron swarm technique

An existing electron swarm apparatus has been redesigned and upgraded. In particular, the new design incorporates a novel planar radioactive foil to form an integral part of the drift tube, allowing us to overcome inherent problems present in our earlier system which used a cylindrical radioactive source. In addition to this, substantial upgrades have been made to improve the gating and amplification electronics and the data acquisition system. This has resulted in a much greater signal to noise ratio and improved accuracy. This paper describes the upgraded apparatus and its use in obtaining thermal (300 K) attachment rate coefficients to a number of molecules. The quality of the measurements and data are illustrated through the measurement of the thermal attachment rate coefficient for SF₆ (k_th(SF₆) = (2.38 ±0.15 ) ×10 ^-7 cm³ s^-1). Thermal electron attachment rate coefficients for four other molecules are presented, namely for two derivatives of SF₆, SF₅CF₃ and SF₅Cl, and two perfluorocarbons, c-C₄F₈ and 2-C₄F₈.     

Detection of genetically modified crops and their derivatives: critical steps in sample preparation and extraction

The detection of genetically modified crops in foodstuff relies on detection of transgenic DNA or protein material in the sample matrix. Purified DNA or proteins are used as analytical material for polymerase chain reaction technologies and immunodiagnostics. Successful sample preparation is critical to the validity of subsequent analysis. For routine analysis, a good sample preparation technique should be simple, safe, and inexpensive while reproducibly generating DNA/protein of sufficient quality and yield. The suitability of isolated DNA or protein as an analyte for a detection or characterization technique depends on amount or concentration, purity, and integrity, each of which may be influenced by sample matrix and the extraction technique, and, in turn, may impact the validity of analytical techniques. The key sample preparation steps of homogenization, pretreatment, extraction, and purification are discussed as well as typical analytical methods. Consideration is given to application of these steps for particular sample matrixes to maximize yield, reduce inhibition effects, and minimize contamination. The choice of the most appropriate and valid methods for sample preparation from particular foods is discussed with respect to DNA analysis. Attention is also given to ease of use, cost, and generic applicability of the procedures.     

Real-time detection of genetically modified soya using Lightcycler and ABI 7700 platforms with TaqMan,Scorpion, and SYBR Green I chemistries

A comparative cross platform evaluation of real-time polymerase chain reaction detection of DNA sequences present in Roundup Ready soya was undertaken using the ABI 7700 and Roche Lightcycler detection systems in combination with 3 different detection chemistries: TaqMan, Scorpion primers, and SYBR Green I fluorescent dye. Various copy numbers of a plasmid containing the soya lectin sequence were used to determine the sensitivity and reproducibility of the different technology combinations and to examine both inter and intra machine variability. To examine the relative accuracy of each technology, the genetically modified soya content of baked products containing known amounts of Roundup Ready soya was determined by detection of lectin and the EPSPS transgene. It was determined that the combination of TaqMan detection chemistry and the ABI 7700 platform represented the best method for quantitative detection of genetically modified organisms in terms of both precision and accuracy.     

A stochastic local search algorithm with adaptive acceptance for high-school timetabling

Automating high school timetabling is a challenging task. This problem is a well known hard computational problem which has been of interest to practitioners as well as researchers. High schools need to timetable their regular activities once per year, or even more frequently. The exact solvers might fail to find a solution for a given instance of the problem. A selection hyper-heuristic can be defined as an easy-to-implement, easy-to-maintain and effective ‘heuristic to choose heuristics’ to solve such computationally hard problems. This paper describes the approach of the team hyper-heuristic search strategies and timetabling (HySST) to high school timetabling which competed in all three rounds of the third international timetabling competition. HySST generated the best new solutions for three given instances in Round 1 and gained the second place in Rounds 2 and 3. It achieved this by using a fairly standard stochastic search method but significantly enhanced by a selection hyper-heuristic with an adaptive acceptance mechanism.