Estimation of non-constant variance in isothermal titration calorimetry using an ITC measurement model.

Isothermal titration calorimetry (ITC) is the gold standard for accurate measurement of thermodynamic parameters in solution reactions. In the data processing of ITC, the non-constant variance of the heat requires special consideration. The variance function approach has been successfully applied in previous studies, but is found to fail under certain conditions in this work. Here, an explicit ITC measurement model consisting of main thermal effects and error components has been proposed to quantitatively evaluate and predict the non-constant variance of the heat data under various conditions. Monte Carlo simulation shows that the ITC measurement model provides higher accuracy and flexibility than variance function in high c-value reactions or with additional error components, for example, originated from the fluctuation of the concentrations or other properties of the solutions. The experimental design of basic error evaluation is optimized accordingly and verified by both Monte Carlo simulation and experiments. An easy-to-run Python source code is provided to illustrate the establishment of the ITC measurement model and the estimation of heat variances. The accurate and reliable non-constant variance of heat is helpful to the application of weighted least squares regression, the proper evaluation or selection of the reaction model

Effects of Hollow CeO2 Nanospheres on Flame Retardance and Smoke Suppression of Room-Temperature-Vulcanized Silicone Rubber

The effects of hollow CeO2 nanospheres on the flame-retardance and smoke-suppression properties of room-temperature-vulcanized (RTV) silicone rubber were studied. It was observed that the flame retardance of RTV silicone rubber composites was improved by hollow CeO2 nanospheres. Surprisingly, the nanospheres also enhanced the smoke-suppression characteristics of the composites. The limited oxygen index of RTV/Mg(OH)(2) was raised from 23.7 to 25.9 by the addition of hollow CeO2 nanospheres, while the smoke density was reduced markedly, from 35.1 to 17.6. The thermal stability and char yield of the RTV silicone rubber composites were characterized by thermogravimetric techniques. Furthermore, the degradation product of the composites was analyzed by pyrolysis-gas chromatography-mass spectroscopy. A mechanism to explain the observed results is proposed

Recent Breakthrough in Layered Double Hydroxides and Their Applications in Petroleum, Green Energy, and Environmental Remediation

The fast development of the world civilization is continuously based on huge energy consumption. The extra-consumption of fossil fuel (petroleum, coal, and gas) in past decades has caused several political and environmental crises. Accordingly, the world, and especially the scientific community, should discover alternative energy sources to safe-guard our future from severe climate changes. Hydrogen is the ideal energy carrier, where nanomaterials, like layered double hydroxides (LDHs), play a great role in hydrogen production from clean/renewable sources. Here, we review the applications of LDHs in petroleum for the first time, as well as the recent breakthrough in the synthesis of 1D-LDHs and their applications in water splitting to H2. By 1D-LDHs, it is possible to overcome the drawbacks of commercial TiO2, such as its wide bandgap energy (3.2 eV) and working only in the UV-region. Now, we can use TiO2-modified structures for infrared (IR)-induced water splitting to hydrogen. Extending the performance of TiO2 into the IR-region, which includes 53% of sunlight by 1D-LDHs, guarantees high hydrogen evolution rates during the day and night and in cloudy conditions. This is a breakthrough for global hydrogen production and environmental remediation