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Abstract

Thermogravimetry (TG) and differential thermal analysis were used to investigate combustion behavior with the addition of cornstalk to coal powder and coal tar at three different heating rates: 5, 10, and 15 °C min−1. Different reaction kinetic mechanisms with the classical Arrhenius model were used to treat TG data. The first-order combustion model fitted the data well. The combustion characteristics of the two masses were analyzed according to combustion characteristics parameters such as ignition temperature, peak temperature at maximum weight loss rate, and burnout temperature, among others. By calculation, a uniform trend of decreasing activation energies was observed with the addition of cornstalk. The rate of coal powder and coal tar combustion process was also greatly improved.

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Abstract  

The neutron temperature is a characteristic parameter in irradiation channels of reactor. For nuclides which have resonances in the thermal neutron energy range, their Westcott g-factors are different from unity. The values of g-factors and cross-sections of (n, γ) reaction of these nuclides are temperature dependence. The standard energy for tabulation of thermal neutron cross-section (σ0) is that of room temperature (293.59 K or 20.43 °C), corresponding to a neutron energy 0.0253 eV or to a neutron velocity of 2200 m/s. However, in the irradiation channels of reactor, the temperature is not exact at 20.43 °C. Thus, the temperature at the irradiation position must be known to convert σ0 to σ(T). A method for determination of the neutron temperature in irradiation channels of Dalat reactor is presented by fitting the thermal neutron spectrum obtained from the calculation using MCNP code.

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Abstract  

Thermal analysis was performed on the anti-HIV agent loviride in order to test its suitability to be processed using hot-melt extrusion. Temperature characteristic parameters of crystallization were determined to quantify the stability of amorphous loviride. The present study has shown that cooling and heating loviride at different rates influenced its thermal stability. At high cooling rates melted loviride did not crystallize during cooling, and formed a glass that recrystallized during reheating. Very low cooling rates resulted in significant decomposition of the drug. The glass transition temperature was found to increase as a function of increasing heating rates and the activation energy for the transition from the glassy to the super-cooled liquid state was relatively high, indicating good stability of the glass.

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Abstract  

Differential scanning calorimetry (DSC) was used in the investigation of the behaviour of coating free films. The films were produced from two film-forming polymers which are chemically different but equally used for producing controlled-release dosage forms: Eudragit NE 30 D (synthetically produced polymethacrylate copolymer) and LustreClear product (mixture containing natural and semi-synthetic components: microcrystalline cellulose, hydroxy-ethyl cellulose, carrageenan and polyethylene glycol). During their comparative analysis the characteristic parameters of the DSC curves obtained with dynamic measurement method were used and their changes as a function of storage conditions and storage time were observed. It was found that the thermoanalytical behaviour of the examined methacrylate-based Eudragit NE and cellulose-based LustreClear films was different. The specific enthalpy change of Eudragit NE fresh films was very little, but it increased considerably during storage. The specific enthalpy change of LustreClear films was much greater but its value shows only a slight further increase during storage. The results obtained help to choose the proper temperature for coating and drying.

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Abstract  

Combustion experiments of three typical seaweeds (Gracilaria cacalia, Enteromorpha clathrata and Laminaria japonica) have been studied using a DTA-60H Thermal Analyzer and the combustion processes and characteristics are studied. Thermogravimetric experiments are carried out on the samples with 0.18 mm particle size at the heating rate of 20°C min−1. The results indicate that the ignition mode of seaweed is homogeneous and the combustion process is composed of dehydration, the pyrolysis and combustion of volatile, transition stage, the combustion of char as well as the reaction at high temperature. And the combustion characteristic parameters are obtained such as ignition temperature, maximum rate of combustion, burnout temperature etc. The combustion models of these seaweeds are also analyzed. The combustion characteristics and model differences between the seaweed and woody biomass are caused by the differences of volatile components. The combustibility indexes of seaweeds calculated are better than that of woody biomass, and the index of Gracilaria cacalia is the best. At last, activation energies are determined using Arrhenius model that is solved by binary linear regression method.

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Abstract  

This study described adsorption of uranium(VI) by citric acid modified pine sawdust (CAMPS) in batch and fixed-bed column modes at 295 K. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Koble–Corrigan and Dubinin–Radushkevich isotherm models. The results indicated that the Langmuir and Koble–Corrigan models provided the best correlation of the experimental data. The Elovish model was better to fit the kinetic process, which suggested that ion exchange was one of main mechanism. The effective diffusion parameter D i values indicated that the intraparticle diffusion was not the rate-controlling step. In fixed-bed column adsorption, the effects of bed height, feed flow rate, and inlet uranium (VI) concentration were studied by assessing breakthrough curve. The Thomas, the Yan and the bed-depth/service time (BDST) models were applied to the column experimental data to determine the characteristic parameters of the column adsorption. The results were implied that CAMPS may be suitable as an adsorbent material for adsorption of uranium (VI) from an aqueous solution.

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burnout temperature is 667 °C) it took just 27 min. Therefore, higher heating rates benefit the combustion process by increasing the combustion rates and decreasing the burning duration. Combustibility characteristic parameters at

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system continued to rise, and ultimately reached to the highest value of 169.03 °C. The thermal characteristic parameters of BPO obtained by ARC experiment are shown in Table 1 . Table 1 Thermal

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the solidification time The characteristic parameters of the insulation layer such as density, specific heat, and heat conductivity of the insulation material relate the temperature changing speed of the crude oil; then the relationship between

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of the full dataset. Table 1 shows the characteristic parameters of the candidate driving cycles. Table 1. Characteristic parameters of the candidate driving cycles Parameter Full dataset DC1 DC2 DC3 DC4 DC5 DC6 DC7 DC8 DC9 DC10 v total (km

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