Comparative study of laser-induced plasma emission of hydrogen from zircaloy-2 samples in atmospheric and low pressure ambient helium gas

An experimental study has been performed to demonstrate the advantage of employing ambient helium gas in the spectral quality improvement of hydrogen emission in laser-induced plasma from zircaloy-2 samples at both atmospheric and low gas pressure. It was further shown that the optimal results achieved in the two pressure regimes require the adoption of different sets of experimental parameters consisting of the laser energy, the focusing lens position and the detection gate delay. A strictly linear calibration line with extrapolated zero intercept was nevertheless exhibited in the case of atmospheric gas pressure only. Additional time-evolution measurement of the emission intensities of hydrogen, helium and zirconium clearly suggests a distinctly different excitation mechanism for hydrogen atoms associated with the presence of ambient helium atoms and their meta-stable excited state. PACS 52.38 Mf     

RAINFALL RATE CONVERSION IN SOUTHEAST ASIA COUNTRIES

The knowledge of 1-minute rainfall rate distribution is very important in order for the prediction of rainfall attenuation at any location. Due to the availability of 1-minute rainfall rate data is limited, conversion of rainfall rate distribution over a long integration time into the distribution for 1-minute is needed. Therefore several rainfall rate conversion methods were proposed.     

Bechtold-Jacobs generalized model for shift scheduling with extraordinary overlap

In constructing working shifts, the classical Dantzig (Operation Research 2:339–341, 1954) set covering model uses a great number of variables which makes computation very complicated for some cases that incorporate a high degree of break-placement flexibility. Bechtold and Jacobs (Management Science 36:1339–1351, 1990) proposed an implicit model under the assumption that there is no extraordinary overlap, which considerably reduced the number of variables. In this paper we give a generalization that is valid without this hypothesis by adding a minimal set of constraints. Also, in some cases where there is extraordinary overlap we reduce our constraint set to a subset with the same number or less than that of Bechtold and Jacobs. I. Addou’s current address is Département de Mathématiques et Statistique, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada, H3C2J7; e-mail: addou@dms.umontreal.ca.     

A Machine Learning Model for the Prognosis of Pulseless Electrical Activity during Out-of-Hospital Cardiac Arrest

Pulseless electrical activity (PEA) is characterized by the disassociation of the mechanical and electrical activity of the heart and appears as the initial rhythm in 20–30% of out-of-hospital cardiac arrest (OHCA) cases. Predicting whether a patient in PEA will convert to return of spontaneous circulation (ROSC) is important because different therapeutic strategies are needed depending on the type of PEA. The aim of this study was to develop a machine learning model to differentiate PEA with unfavorable (unPEA) and favorable (faPEA) evolution to ROSC. An OHCA dataset of 1921 5s PEA signal segments from defibrillator files was used, 703 faPEA segments from 107 patients with ROSC and 1218 unPEA segments from 153 patients with no ROSC. The solution consisted of a signal-processing stage of the ECG and the thoracic impedance (TI) and the extraction of the TI circulation component (ICC), which is associated with ventricular wall movement. Then, a set of 17 features was obtained from the ECG and ICC signals, and a random forest classifier was used to differentiate faPEA from unPEA. All models were trained and tested using patientwise and stratified 10-fold cross-validation partitions. The best model showed a median (interquartile range) area under the curve (AUC) of 85.7(9.8)% and a balance accuracy of 78.8(9.8)%, improving the previously available solutions at more than four points in the AUC and three points in balanced accuracy. It was demonstrated that the evolution of PEA can be predicted using the ECG and TI signals, opening the possibility of targeted PEA treatment in OHCA.     

The kinetics of the reduction of tetraoxoiodate(VII) by <Emphasis Type="Italic">n</Emphasis>-(2-hydroxylethyl)ethylenediaminetriacetatocobaltate(II) ion in aqueous perchloric acid

The stoichiometries, kinetics and mechanism of the reduction of tetraoxoiodate(VII) ion, IO₄ ⁻ to the corresponding trioxoiodate(V) ion, IO₃ ⁻ by n-(2-hydroxylethyl)ethylenediaminetriacetatocobaltate(II) ion, [CoHEDTAOH₂]⁻ have been studied in aqueous media at 28 °C, I = 0.50 mol dm⁻³ (NaClO₄) and [H⁺] = 7.0 × 10⁻³ mol dm⁻³. The reaction is first order in [Oxidant] and [Reductant], and the rate is inversely dependent on H⁺ concentration in the range 5.00 × 10⁻³ ≤ H⁺≤ 20.00 × 10⁻³ mol dm⁻³ studied. A plot of acid rate constant versus [H⁺]⁻¹ was linear with intercept. The rate law for the reaction is:

Palladium-catalyzed decarboxylative aminocarbonylation with alkynoic acid and tertiary amine for the synthesis of alkynyl amide

We developed a method for the synthesis of alkynyl amides via the carbonylation of alkynoic acids and C-N activation of tertiary amines. The reaction of alkynoic acid and tertiary amine with carbon monoxide using a palladium catalyst in the presence of oxygen, KI, and K₃PO₄, gave the desired alkynyl amides in good yields.     

Effect of high temperature on reduction-controlling reaction rate of agricultural waste chars and coke with steelmaking slag

In the present research, mechanical and thermal properties of high-density polyethylene/wood flour were improved by incorporating nanoclay (Cloisite 30B) and antioxidant (Irganox B225) in the compound. Design of experiments was carried out to optimize composition among nine compounds and to investigate the effect of nanoclay and antioxidant (0–5 phr) and (0–0.4 phr), respectively. The results of mechanical tests showed approximately 24% increase in the tensile strength of compounds containing 2.5 and 5.0 part per hundred (phr) of the nanoclay in the composite compared with the same samples without nanoclay. The tensile modulus of composites increased 7.3% by increasing the level of nanoclay from 0 to 2.5 phr. However, a further increase in the nanoclay content led to a 4.3% decrease in tensile modulus. Evaluation of the thermal oxidation stability of samples confirmed that the thermal oxidation of composites decreased with increasing nanoclay from 0 to 5.0 phr and increased significantly with the addition of the antioxidant.

     

Preparation and characterization of the polymer electrolyte system ENR50/PVC/EC/PC/LiN(CF<Subscript>3</Subscript>SO<Subscript>2</Subscript>)<Subscript>2</Subscript> for electrochemical device applications

Polymer electrolytes containing epoxidised natural rubber (ENR50)/poly(vinyl chloride) (PVC) blend as a polymer host, a solvent mixture of ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizer, and lithium imide, LiN (CF₃SO₂)₂, as a salt were studied. Polymer electrolytes that were obtained by solvent cast yielded solid dry rubbery films with a thickness range of 110–125 μm. Impedance spectroscopy, Fourier transform infra red (FTIR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were performed on these samples. The prepared solid polymer electrolytes exhibit ionic conductivities in the order 10⁻⁴ S cm⁻¹ at room temperature as expected. However, the physical properties of the electrolytes have improved significantly when optimal composition has been selected. Paper presented at the International Conference on Solid State Science and Technology 2006, Kuala Terengganu, Malaysia, Sept. 4–6, 2006.     

Some notes on the role of meta-stable excited state of helium atom in laser-induced helium gas breakdown spectroscopy

A study of the experimental results on the plasma emissions of water and ethanol vapor samples, induced by Nd:YAG laser in ambient helium and nitrogen gases at atmospheric pressure, is presented here. The result reveals distinct geometrical and spectral characteristics of the plasma emissions generated in the helium gas when compared to those observed from nitrogen gas plasma. Most remarkable is the narrow line width and low continuum background exhibited by emission lines of the analyte atoms from helium plasma, including the hydrogen emission line which is known to suffer from notorious broadening effects in conventional laser induced breakdown spectroscopy (LIBS). It is further shown on the basis of the measured spatial distributions and time profiles of the emission intensities, that the excellent spectral quality is attained by taking advantage of the meta-stable excited state of helium atoms for the delayed excitation of the hydrogen and other analyte atoms, this allows the detection of those atomic emissions to be performed under more favorable conditions. The result of this study has thus demonstrated the feasibility of achieving high-quality spectrochemical analysis, including hydrogen analysis with laser-induced helium gas breakdown spectroscopy. PACS 52.38.Mf