Accurate measurement of magnesium content in alphaolefins by laser induced breakdown spectroscopy （LIBS） technique

In this paper,results are presented on first application of laser-induced breakdown spectroscopy(LIBS) technique for quantitative determination of Mg concentration in alpha-olefins. It is demonstrated that this technique gives accuracies in Mg concentrations which are comparable with those of traditional methods,as ICP-OES,in short times and without need for sample preparation. Limits of detection for Mg of the order of 500 ppb are demonstrated. Moreover,a brief discussion about the realization of proper calibration curves and the definition of the limit of detection(LOD) is reported.     

Damage production in GaAs during MeV ion implantation

The influence of the nuclear and electronic energy loss on the damage production in GaAs has been studied by Se⁺ ion implantation at T_I = 293 K with energies ranging from 2 MeV up to 20 MeV. The ion dose was varied between 5 × 10¹² /cm² and 1 × 10¹⁵ /cm². The damage production was investigated using RBS in channeling regime. Temperature and energy dependent backscattering measurements and TEM investigations were performed to study the kind of defects in more detail. The resulting defect profiles are compared with the depth distribution of the nuclear and electronic energy loss which were simulated by TRIM 87. The results show that the remaining defect concentration strongly decreases with increasing implantation energy even if the same energy density is deposited into nuclear processes. We suppose, that the electronic energy loss increases the defect transformation and annealing during implantation at T_I = 293 K. The defects in the samples implanted with energies greater than 5 MeV are characterized as point defects, point defect clusters and small dislocation loops; the kind of defects are the same over the whole implantation depth and the existence of amorphous zones can be widely excluded.     

A decision model for energy resource selection in China

This paper evaluates coal, petroleum, natural gas, nuclear energy and renewable energy resources as energy alternatives for China through use of a hierarchical decision model. The results indicate that although coal is still the major preferred energy alternative, it is followed closely by renewable energy. The sensitivity analysis indicates that the most critical criterion for energy selection is the current energy infrastructure. A hierarchical decision model is used, and expert judgments are quantified, to evaluate the alternatives. Criteria used for the evaluations are availability, current energy infrastructure, price, safety, environmental impacts and social impacts.     

Determination of the surface area of dispersed ruthenium by reactive nitrous oxide chemisorption

The interaction of nitrous oxide with ruthenium surfaces was studied in order to develop a fast and reliable method for the determination of the metallic surface area and dispersity of ruthenium catalysts as alternative to the established chemisorption methods using hydrogen, carbon monoxide or oxygen as probe molecule. Studies of the temperature dependence of the reactive or dissociative chemisorption of nitrous oxide using pulse technique showed that an oxygen monolayer of almost constant stoichiometry is formed in a narrow temperature range around 403 K. However, so-called ‘rest nitrogen peaks' were observed after saturation of an O-monolayer revealing a small additional nitrous oxide conversion which could be attributed to formation of subsurface oxygen by means of back-titration of the oxygen totally uptaken. This additional nitrous oxide consumption can be minimised by an adjustment of both the N₂O-sampling loop volume and the catalyst sample weight in order to obtain an oxygen monolayer saturation by few pulses, and moreover, it can be considered as a correction for the calculation of the oxygen monolayer. A specific nitrous oxide consumption of 13.5 μmol/m²_Ru has been determined on ruthenium black by means of alternating measurements of the nitrogen physisorption and N₂O-pulse chemisorption. The reliability of the new method for characterisation of the dispersity or surface area of supported ruthenium was proved with ruthenium highly dispersed on γ-alumina.     

Recursive estimation of quantitles using recursive kernel density estimators

Recursive estimation of quantiles may be obained via adaptive stochastic approximation

approximation theorms can be used to obtained the asympotic properties when the obervation are independent. for dependent sequences matingale theory cannot be applied straight forwardly as the tool for asympototic analysis.In this paper we consider both the case when the observation are i.i.d. and when they form a stationary and strongly regular process.the main result is sufficient condition for almost sure convergence in the strongly regular case.     

Morphological controlled synthesis of micro-/nano-polyaniline

A novel, highly efficient and economical route is developed for the synthesis of polyaniline micro-/nanostructure. Materials were characterized by a complementary combination of X-ray diffraction, Scanning electron microscopy, Fourier-transform infrared, and UV-visible spectrophotometer. Morphology of polyaniline can be tailored by varying the structure-directing agents and pH of the synthesis condition. Ethylene glycol and polyethylene glycol formed a three-dimensional flower-like structure whereas block-copolymer (ethylene oxide and propylene oxide based co-polymer EO₂₀PO₇₀EO₂₀) formed leaf-like structure when the synthesis was performed at pH 7. Using these structure-directing agents, nanorod and granular morphologies were obtained when the samples were synthesized at pH 3 and 1, respectively.