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- Author or Editor: K. Wu x
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Abstract
The thermotropic phase transitions in the perovskite type layer compound (n-C10H21NH3)2MnCl4 and (n-C14H29NH3)2MnCl4 were synthesized and, at the same time, a series of their mixtures C10Mn-C14Mn were prepared. The experimental binary phase diagram of C10Mn-C14Mn was established by differential thermal analysis (DTA), IR and X-ray diffraction. In the phase diagram new material (n-C10H21NH3)(n-C14H29NH3)MnCl4 and two eutectoid invariants were observed, two eutectic points temperatures are about 29.8 and 27.9°C. Contrasting other similar system, there are three noticeable solid solution ranges (α, β, γ) at the left and right boundary and middle of the phase diagram.
Abstract
Information about the kinetics and thermal decomposition of dicumyl peroxide (DCPO) is required for safety concerns, due to its wide applications and accident cases. To understand the inherent hazards during DCPO manufacturing, we selected various concentrations in different stages and analyzed them by differential scanning calorimetry (DSC). We evaluated thermokinetic parameters to set up a simple, but comprehensive kinetic model, with various tests conducted at heating rates of 2, 4, 6 and 10C min-1 . Subsequently, we established a more efficient, resource-effective, and cost-effective model of safety evaluation for DCPO with different concentrations, according to thermokinetic parameters, such as activation energy E a is 125.35 kJ mol-1 , frequency factor k 0 is 3.12410 12 s-1 , reaction order n is 0.9 and heat of decomposition ΔH is 750.52 J g-1 for DCPO 99 mass%.
Abstract
One of the most critical elements of a performance evaluation (PE) program for radioactivity measurements is the traceability of the PE materials to the national standards. The requirements and criteria for the production of traceable environmental and radiobioassay PE materials have been defined by ANSI N42.22 and ANSI N13.30 standards. It is important to note that use of traceable source materials does not necessarily ensure the traceability of subsequently derived PE materials unless verification measurements exist in conjunction with the preparation processes. This paper describes the protocol currently used by NIST for the preparation and verification of air filter, acidified water, spiked soil, synthetic urine, and synthetic fecal PE materials for low-level radioactivity measurements. The process involves gravimetric dilutions and mixing of primary radionuclide NIST Standard Reference Materials (SRMs), addition of the derived master solution to sample matrices, and subsequent verification measurements. Several gamma-emitters were used to trace the gravimetric dilutions and spike addition through an unbroken chain of gamma comparison measurements. The massic activities of alpha- and beta-emitters in the diluted solutions and PE samples were also measured by radiochemical methods and compared with their gravimetric values. A correlation analysis demonstrated that the gamma emitters quantitatively followed 90Sr, 238U, 238Pu, and 241Am throughout the dilution and spiking and can be used as effective process monitors. The statistical results from t-tests, box plots, and normal probability tests suggested that traceability of radionuclides in the PE materials to their primary standards can be verified to within 1%, with an overall precision better than 2% (1s).
Abstract
A total reflection X-ray fluorescence (TXRF) analyzer with a special structure is described. Its short X-ray path (about 15 cm) resulted in a high sensitivity, low power consumption and small volume. The structure with double total reflection path is suitable for easy change of exciting source to cover a large element range. The minimum detection limit (MDL) of 6 pg for Co under Cu exciting source and 22 pg for Sr under Mo tube. Some significant works were done, such as the detemination of sulfur content in fuel oils, the non-destructive analysis of an ancient bronze utensil and the regular analysis of tap water.
Abstract
This work discusses thermal behavior of Ni/MH battery with experimental methods. The present work not only provides a new way to get more exactly parameters and thermal model, but also concentrates on thermal behavior in discharging period. With heat generation rate gained by experiments with microcalorimeter, heat transport equations are set up and solved. The solutions are compared with experiment results and used to understand the reactions inside the battery. Experiments with microcalorimeter provide more reliable data to create precise thermal model.
Abstract
This study utilized Fenton, Fenton-like, photo-Fenton, photo-Fenton-like, sono-Fenton, and sono-Fenton-like systems for the decolorization of Reactive Red 2 (RR2) dye. Fe2+ and Fe3+ were used to catalyze the actions of oxidants H2O2 and Na2S2O8. Pseudo-first order rate constants (k) were obtained by fitting the decolorization kinetics of RR2. With added oxidant at 0.3 mM and iron ion at 0.03 mM, the k values of H2O2/Fe2+, H2O2/Fe3+, Na2S2O8/Fe2+, and Na2S2O8/Fe3+ were 13, 0.67, 6.2, and 0.080 r−1, in order. Higher oxidant and iron concentrations resulted in faster decolorization in Fenton and Fenton-like systems. Additionally, decolorization was accelerated by ultraviolet (UV) and ultrasound (US) irradiation. When ethanol was used as a scavenger for the generated hydroxyl and sulfate radicals, it significantly inhibited the decolorization process in photo-Fenton and photo-Fenton-like systems. The k values obtained for the UV/H2O2/Fe2+, UV/Na2S2O8/Fe2+, UV/H2O2/Fe2+/C2H5OH, and UV/Na2S2O8/Fe2+/C2H5OH systems were 23, 14, 0.36, and 0.69 h−1, in order.
Abstract
Hydrogen peroxide (H2O2) is popularly employed as a reaction reagent in cleaning processes for the chemical industry and semiconductor plants. By using differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), this study focused on the thermal decomposition reaction of H2O2 mixed with sulfuric acid (H2SO4) with low (0.1, 0.5 and 1.0 N), and high concentrations of 96 mass%, respectively. Thermokinetic data, such as exothermic onset temperature (T 0), heat of decomposition (ΔH d), pressure rise rate (dP/dt), and self-heating rate (dT/dt), were obtained and assessed by the DSC and VSP2 experiments. From the thermal decomposition reaction on various concentrations of H2SO4, the experimental data of T 0, ΔH, dP/dt, and dT/dt were obtained. Comparisons of the reactivity for H2O2 and H2O2 mixed with H2SO4 (lower and higher concentrations) were evaluated to corroborate the decomposition reaction in these systems.
Abstract
The two complexes of [Ln(CA)3bipy]2 (Ln = Tb and Dy; CA = cinnamate; bipy = 2,2′-bipyridine) were prepared and characterized by elemental analysis, infrared spectra, ultraviolet spectra, thermogravimetry and differential thermogravimetry techniques. The thermal decomposition behaviors of the two complexes under a static air atmosphere can be discussed by thermogravimetry and differential thermogravimetry and infrared spectra techniques. The non-isothermal kinetics was investigated by using a double equal-double steps method, the nonlinear integral isoconversional method and the Starink method. The mechanism functions of the first decomposition step of the two complexes were determined. The thermodynamic parameters (ΔH ≠ , ΔG ≠ and ΔS ≠ ) and kinetic parameters (activation energy E and the pre-exponential factor A) of the two complexes were also calculated.
The present study was performed to investigate the effect of β-aminobutyric acid (BABA) treatment on defence activation in grape berries and to analyse its cellular mechanism. The results implied that BABA treatment at an effective concentration of 20 mM significantly inhibited gray mould rot caused by Botrytis cinerea in grape berries by inducing resistance. Accordingly, 20 mM BABA triggered a priming defence in grape suspension cells, since only the BABA-treated cells exhibited an accelerated ability for augmenting defence responses upon the pathogen inoculation. The primed cellular reactions were related to an early H2O2 burst, prompt accumulation of stilbene phytoalexins and activation of PR genes. Thus, we assume that 20 mM BABA can induce resistance to B. cinerea infection in intact grape berries perhaps via intercellular priming defence. Moreover, the BABA-induced priming defence is verified, because no negative effects on cell growth, anthocyanin synthesis, and quality impairment in either grape cells or intact berries were observed under low pathogenic pressure.
Fusarium graminearum causes gibberella ear rot in maize. The incidence and severity of the disease is strongly influenced by environmental factors and can reach epidemic levels. The infection can result in severe reduction in crop quality because of contamination of the grain with trichothecene mycotoxins. The best strategy for control of the disease is to develop resistant hybrids. Unfortunately, most commercial maize hybrids currently grown in Canada have little or no resistance to infection by Fusarium graminearum . In a previous study, we identified several Quantitative Trait Loci (QTL) for resistance to gibberella ear rot in maize. The focus of this work was to identify genes underlying those QTLs by using microarray-based Comparative Genomic Hybridization (CGH). The 46K maize 70-mer oligo microarray (University of Arizona) was hybridized with the Alu I digested genomic DNA from CO387 (resistant) and CG62 (susceptible) parental lines and with the pooled resistant and susceptible recombinant inbred lines from the CG62 × CO387 population. Approximately one hundred of genes (t-test) had significant hybridization intensity differences between resistant and susceptible parents and pools. Some of these genes (chitinase, protein kinase) were similar to previous gene-based markers that were identified to cosegregate with Fusarium resistance QTLs. The identified resistance genes will be converted into markers that can easily be scored to allow rapid introgression of gibberella ear rot resistance into elite germplasm.
