A radiometric procedure for quantitative analysis of traces of silver in galena has been demonstrated. The mineral sample was dissolved in HNO3 (31) and silver present in the solution was precipitated as insoluble AgI by adding an excess amount of131I-labeled KI solution and was coprecipitated with zirconium hydrogen phosphate, Zr(HPO4)2, in 0.5N H2SO4 medium. The method of radiometric analysis of silver which was estimated from the knowledge of the loss of131I activity in solution, was found to be effective in determination of the element even below ppb level. Applicability of the radiometric procedure in routine analysis or preconcentration of traces of silver in galena has been stressed.
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 Ea 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 Cp mode of mircocalorimeter. Using the relationship between Cp and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic
time-to-explosion) was obtained.
To investigate the effects of 3-month-long specific training program on biochemical status, oxidative and antioxidant responses in elite karatekas.
Twenty male karatekas [BMI: 21.9 ± 2.4 (kg/m2)] participated in this study. They performed a 3-month specific training to prepare for an international competition. We measured selected biochemical parameters, the oxidative and antioxidant responses before (T0) and after 3 months of intense karate training (T1).
We found significant increases in catalase activity (26.3% ± 21.3%, p < 0.0005), superoxide dismutase activity (15.9% ± 28.8%, p < 0.05), and a significant decrease in malondialdehyde levels (17.2% ± 13.7%, p < 0.0005) after 3 months of karate training. Moreover, the athletes’ biochemical status was significantly improved at T1 compared with T0 (for the majority of parameters, p < 0.0005).
The specific training program improves the prooxidant–antioxidant balance of elite karate athletes. It could be recommended for athletes having similar physical fitness level.
Authors:P. Zhang, M. Zhou, X. Zhang, Y. Huo, and H. Ma
Crown rot caused by Fusarium pathogens is one of the most economically destructive diseases of wheat. The objective of this study was to investigate defense-related enzyme responses in wheat seedlings infected with Fusarium graminearum. Three wheat varieties were employed to the experiment. Physiological analysis of varieties indicated that defensive-related enzymes were induced by F. graminearum infection. The superoxide dismutase and peroxidase activities increased dramatically and the phenylalanine ammonia-lyase activity was stimulated to a higher level in resistant variety Hongyouzi than in susceptible variety Wo0102. However, the chitinase activity was higher in susceptible variety Wo0102 than in Hongyouzi after infection. These results suggest that the defense enzymes could be stimulated in wheat seedlings by Fusarium infection.
Authors:J. Zhu, H. Jin, D. Dong, D. Qiang, and F. Ma
The glass formation and devitrification of GaF3-based glasses were studied by differential scanning calorimetry. A comparison of various simple quantitative methods to assess
the level of stability of multicomponent fluoride glass systems is presented. Most of these methods are based on critical
temperatures. In this paper a new parameter kb(T) is added to the stability criteria. The stability of several GaF3-based glasses were experimentally evaluated and correlated with the activation energies of crystallization via this new kinetic
criterion and compared with those evaluated by other criteria.
Authors:H.-D. Wang, Y.-T. Li, P.-H. Ma, and X.-C. Zeng
A complex of N,N'-ethylenebis(salicylideneiminato)diaquochromium(III) nitrate, [Cr(salen)(H2O)2]NO3 was characterized and its decomposition mechanism was studied by TG. The IR spectrum and X-ray analysis were examined for the complex. The non-isothermal kinetic data were analyzed by means of the Achar method and the Coats—Redfern method. The most probable kinetic model function was suggested by comparison of the kinetic parameters.
Authors:Y. Qi, F. Xu, H. Ma, L. Sun, J. Zhang, and T. Jiang
Polyaniline/γ-Al2O3 (PANI/γ-Al2O3) composites were synthesized by in-situ polymerization at the presence of HCl as dopant by adding γ-Al2O3 nanoparticles into aniline solution. The composites were characterized by FTIR and XRD. The thermogravimetry (TG) and modulated
differential scanning calorimetry (MDSC) were used to study the thermal stability and glass transition temperature (Tg) of the composites, respectively.
The results of FTIR showed that γ-Al2O3 nanoparticles connected with the PANI chains and affected the absorption characteristics of the composite through the interaction
between PANI and nano-sized γ-Al2O3. And the results of XRD indicated that the peaks intensity of the PANI/γ-Al2O3 composite were weaker than that of the pure PANI. From TG and derivative thermogravimetry (DTG) curves, it was found that
the pure PANI and the PANI/γ-Al2O3 composites were all one step degradation. And the PANI/γ-Al2O3 composites were more thermal stable than the pure PANI. The MDSC curves showed that the nano-sized γ-Al2O3 heightened the glass transition temperature (Tg) of PANI.
Authors:D. Ma, D. Paik, D. Park, H. Moon, Y. Chang, and J. Kim
The remineralization effect of fluoride has been measured by surface microhardness on tooth enamel. The purpose of this study was to investigate the relationship between microhardness and fluorine concentration on tooth enamel. Twelve sound bovine enamel specimens were prepared and immersed in 0.05% NaF solution for 1, 3, 6, 24 and 36 hours, respectively. The concentration of fluorine in specimens were measured by PIGE analysis and surface microhardness of each specimen was measured by surface microhardness tester. Fluorine concentration was increased by immersing time. There was no change in microhardness of each specimen by fluorine content. The results of this study suggest that there was no relationship between the fluorine concentration and surface microhardness in sound tooth enamel. PIGE analysis can be used effectively to assess the remineralization effect of fluorine content in tooth enamel.
Authors:D. Paik, D. Ma, D. Park, H. Moon, Y. Chang, and J. Kim
The purpose of this study was to evaluate the effectiveness of a toothpaste containing bamboo salt on fluorine uptake in bovine enamel and to compare the efficiency of fluorine uptake between sodium monofluorophosphate (SMFP) toothpaste and sodium fluoride (NaF) mouthrinsing solution using proton induced -ray emission analysis. 30 bovine tooth enamel specimens were prepared and assigned to 5 groups as follows: (a) specimens without any treatment, (b) specimens which were treated with a toothpaste containing dicalcium phosphate dihydrate (DCPD) only, (c) specimens which were treated with a toothpaste containing DCPD and SMFP, (d) specimens which were treated with a toothpaste containing DCPD, SMFP and 2% bamboo salt, (e) specimens which were treated with 0.05% NaF mouthrinsing solution. After 5 and 10 hours of treatment, fluorine concentration was measured at the depth of 263, 625, 2530 nm from the surface of the specimens. The surface concentration of fluorine was markedly increased using SMFP dentifrice. Bamboo salt did not encourage the uptake of fluorine into the enamel surface. NaF mouthrinsing solution showed a considerably higher uptake of fluoride in the intact enamel surface than the SMFP dentifrices.
Authors:S. Mishra, S. Maity, S. Bhalke, G. Pandit, V. Puranik, and H. Kushwaha
In order to understand the mobility of uranium it is very important to know about its sorption kinetics and the thermodynamics
behind the sorption process on soil. In the present study the sorption kinetics of uranium was studied in soil and the influence
parameters to the sorption process, such as initial uranium concentration, pH, contact time and temperature were investigated.
Distribution coefficient of uranium on soil was measured by laboratory batch method. Experimental isotherms evaluated from
the distribution coefficients were fit to Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models. The sorption energy
for uranium from the D–R adsorption isotherm was calculated to be 7.07 kJ mol−1.The values of ΔH and ΔS were calculated to be 37.33 kJ mol−1 and 162 J K−1 mol−1, respectively. ΔG at 30 °C was estimated to be −11.76 kJ mol−1. From sorption kinetics of uranium the reaction rate was calculated to be 1.6 × 10−3 min−1.