TG and DTA analysis of Y1−xCaxBa2Cu3O7−y suggests that the stability of the 123 phase increases with increasing Ca contents. The O(1) in the Cu(1)-O chain is unstable
but O(2) and O(3) in Cu(2)-O planes are very stable. There are hardly any oxygen vacancies in the Cu(2)-O plane. The replacement
of Y by Ca does not make oxygen vacancies in Cu(2)-O planes but leads to an increase in the oxidation number of copper in
Authors:Y. Chen, H. Wang, X. Meng, X. Zeng and J. Xie
A novel thermokinetic research method for determination of the rate constant of a reaction taking place in a batch conduction
calorimeter under isothermal conditions is proposed: the double-thermoanalytical curve method. The method needs only the characteristic
time parameter tm, the peak height Δm at time tm and the peak area a*m after time tm for two thermoanalytical curves measured with different initial concentrations of the reactants: it conveniently calculates
the rate constants. The thermokinetics of four reaction systems were studied with this method, and its validity was verified
by the experimental results.
Authors:X. Zeng, Y. Chen, S. Cheng, X. Meng and Q. Wang
A novel method for the determination of rate constants of reactions, the time-variable method, is proposed in this paper. The method needs only three time points (t), peak heights () and pre-peak areas (), obtained from the measured thermoanalytical curve. It does not require the thermokinetic reaction to be completed. It utilizes data-processing on a computer to give the rate constants. Four reaction systems, including a first-order reaction, second-order reactions (with equal concentrations and with unequal concentrations) and a third-order reaction, were studied with this method. The method was validated and its theoretical basis was verified by the experimental results.
Authors:X. Zhang, Y. Ding, Y. Zhang, Y. Hao, G. Meng and L. Zhang
Highly oriented single crystal antimony nanowire arrays have been synthesized within anodic aluminum oxide (AAO) template
by pulsed electrodeposition. Thermal behavior and oxidation analysis of the antimony nanowires have been investigated by means
of thermogravimetry and differential scanning calorimetry in Ar and air atmosphere, respectively. Compared to bulk antimony,
the antimony nanowires exhibit a lower sublimation temperature at 496.4°C. Evident oxidation of the Sb nanowires occurs at
429.8°C in air atmosphere and α-Sb2O4 nanowires have been obtained as the oxidation product. The results indicate that the sublimation and the oxidation of the
antimony nanowires in the AAO template is a slow multi-step process. The present results are of relevance when processing
antimony nanowries for thermoelectric applications at high temperatures.
Authors:J. Li, L. Liu, C. Li, L. Liu, Y. Tan and Y. Meng
The purpose of this study was to evaluate the ability of Lactobacillus rhamnosus to bind patulin (PAT) in the buffer solution and apple juice. The binding of L. rhamnosus to PAT was reversible, which improved the stability of the bacterial complex. The ability to bind PAT can be enhanced with the inactivation of the strain by high temperature and acid treatment. Acid-treated bacteria had the highest PAT binding rate of 72.73±1.05%. The binding rates of acid and high temperature (121 °C) treatments were increased by 21.37% and 19.15%, respectively. L. rhamnosus showed the best detoxification ability to PAT at 37 °C, where the binding rate reached 50.9±1.03%. When the dose of inactivated bacteria powder was 0.02 g ml−1, the minimum concentration of PAT in apple juice was 0.37 µg ml−1. The addition of the L. rhamnosus inactivated powder did not affect the quality of the juice product and effectively bound the PAT in apple juice.
Authors:Y.-Q. Zhang, X.-C. Zeng, Y. Chen, X.-G. Meng and A.-M. Tian
On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.
Authors:G.W. Shu, D.L. Ma, H. Chen, J.P. Meng, Y. Wang and N. Xin
The present study was to evaluate the survival rate of free and encapsulated Bifidobacterium bifidum BB28 under simulated gastrointestinal conditions and its stability during storage. Results showed that non-microencapsulated Bifidobacterium bifidum BB28 was more susceptible to simulated gastrointestinal conditions than microencapsulated bacteria. Microencapsulated Bifidobacterium BB28 exhibited a lower population reduction than free cells during exposure to simulated gastrointestinal conditions, the viable count of monolayer microcapsules, double layer microcapsules, and triple layer microcapsules decreased by nine magnitudes, four magnitudes, and one magnitude after 2 h, respectively. The enteric test showed that the microorganism cells were released from the monolayer, double layer, and triple layer microcapsules completely in 40 min. Moreover, the optimum storage times of free Bifidobacterium BB28, monolayer microcapsules, double layer microcapsules, and triple layer microcapsules were 21 days, 21 days, 28 days, and more than 35 days in orange juice, pure milk, and nutrition Express (a commercially available milk based drink), and the viable counts were maintained at 1×106 CFU g−1 or more, which means that the double layer and triple layer of microcapsules of B. bifidum BB28 have great potential in food application.
Authors:L. Li, Z.-C. Tan, S.-H. Meng, S.-D. Wang and D.-Y. Wu
The catalytic and accelerating effects of three coal-burning additives (CBA) on the burning of graphite were studied with
the help of thermogravimetric (TG) analysis. The kinetic study on the catalytic oxidation of the graphite doped with CBA was
carried out and the results were presented. The results show that the CBA can change the carbon oxidation/combustion course
by catalytic action and change the activation energy, thus improving the combustion efficiency.