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  • Author or Editor: J. Ma x
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Abstract  

As an altemative to129I measurement by X-ray spectrometry or ICPMS, we explored the possibilities of activation analysis using thermal or 14 MeV neutrons. Preliminary qualitative measurements were done with samples of about 5 mg. These samples were exposed to two neutron sources:252Cf and DT neutron generator. The most interesting reaction is the neutron capture which leads to useful signatures at 536.1, 668.5, and 739.5 keV, associated with a half-life of 12.36 h.

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The pyrolysis of a suite of brown coal samples and bituminous coal maceral concentrates is investigated by non-isothermal thermogravimetry. The TG data for these coals reveal a two-stage pyrolysis process. The activation energy for the primary pyrolysis stage is considerably higher than that for the secondary pyrolysis stage. It is evident that a particular coal may be characterised by the weighted mean apparent pyrolysis activation energy which correlates with the corresponding specific energy of the coal.

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A total of 232 accessions of tetraploid species, durum wheat (Triticum turgidum L. ssp. durum Desf., 2n=4x=28, AABB) with a widespread origin of various countries were used in this study. Their high molecular weight glutenin subunit (HMW-GS) composition was identified by Matrix-assisted laser desorption/ionization time-of-flight Mass Spectrometry (MALDI-TOF-MS). Among all accessions analyzed, 194 were homogeneous for HMW-GS, 38 were heterogeneous, and 62 possessed unusual or new subunits. The results revealed a total of 43 alleles, including 5 at Glu-A1 and 38 at Glu-B1, resulting in 60 different allele combinations. The Glu-B1 locus displayed higher variation compared with Glu-A1. Glu-A1c (55.2%) and Glu-B1aj (17.7%) were the most frequent alleles at Glu-A1 and Glu-B1, respectively. Two allele types (“null” and 1) at the Glu-A1 locus and three allele types (7OE + 8, 14+15, 8) at the Glu-B1 locus appeared to be the common types in the 232 accessions. A total of 23 new alleles represented by unusual subunits were detected at the Glu-A1 and the Glu-B1 locus.

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Abstract  

Rare earth complexes ofm-nitrobenzoic acid (LnL3·2H2O,Ln=La-Lu and Y, except Pm, HL=m-nitrobenzoic acid) were synthesized and characterized by elemental analysis, chemical analysis, IR spectroscopy and X-ray diffraction analysis. The dehydration behaviour of these complexes was studied in detail by means of TG-DTA and DSC. Dehydration occurs over the temperature range 76–215°C, and the temperature of formation of the anhydrous complexes decreases with increasing atomic number of the rare earth. The activation energies and enthalpy changes for te dehydration were obtained.

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Abstract  

Sequestration of radioactive nickel (63Ni2+) in fly ash coming from hospital wastes incineration plant by incorporating nano-goethite as a function of pH, particle size and the ratio of solid and liquid was investigated under the batch leaching experiments. The synthetic nanogoethite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and specific surface area (SSA). The admired needle nanogoethite was obtained in terms of XRD, TEM and SSA analysis. Approximate 5% of 63Ni2+ was desorbed from the nanogoethite/fly ash composite under the circum natural pH conditions. The ratio of solid to liquid has little effect on desorption of 63Ni2+ from nanogoethite/fly ash composite. These results indicate that the radioactive nickel in fly ash can be sequestrated by incorporating nanogoethite. The results may play significantly a role in immobilization in situ of trace radionuclides in the natural environment.

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Abstract  

The title compound 3,3-dinitroazetidinium (DNAZ) 3,5-dinitrosalicylate (3,5-DNSA) was prepared and the crystal structure has been determined by a four-circle X-ray diffractometer. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC and TG/DTG techniques. The kinetic parameters were obtained from analysis of the TG curves by Kissinger method, Ozawa method, the differential method and the integral method. The kinetic model function in differential form and the value of E a and A of the decomposition reaction of the title compound are f(α)=4α3/4, 130.83 kJ mol−1 and 1013.80s−1, respectively. The critical temperature of thermal explosion of the title compound is 147.55 °C. The values of ΔS , ΔH and ΔG of this reaction are −1.35 J mol−1 K−1, 122.42 and 122.97 kJ mol−1, respectively. The specific heat capacity of the title compound was determined with a continuous C p mode of mircocalorimeter. Using the relationship between C p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic time-to-explosion) was obtained.

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