Study on effects of sweating treatment and different drying methods on the quality of Gentianae macrophyllae Radix.

To provide basis for improving the quality of Gentianae macrophyllae Radix and optimising the field processing method. Gentianae macrophyllae Radix samples were collected from Long County. Five main active iridoids were determined by using HPLC. The HPLC fingerprints were measured and analysed by the traditional Chinese medicine chromatographic fingerprint similarity evaluation system. Water, total ash, acid insoluble ash and ethanol extract contents were determined in accordance with Chinese Pharmacopoeia (2015). Colour of the surface and powdered samples were determined by using a colorimeter. Data were analysed by SPSS11.0. Notable differences were found among samples from different sweating and drying processes, in spite of the relatively consistent overall chemical characteristics. Sweating and drying methods influenced the contents of some active ingredients and colour very significantly; moreover, they also showed significant effects on the water, ash, and ethanol extract contents. The necessity of sweating treatment in the field processing of Gentianae macrophyllae Radix may be insufficient. Drying in the shade and oven drying are more profitable for preserving the active constituents. Gentianae macrophyllae Radix should be dried directly without sweating, and drying in the shade and oven drying should be adopted preferentially to improve the quality.

Ultrasound-assisted fast encapsulation of metal microparticles in SiO2 via an interface-confined sol-gel method.

Although the traditional Stoˇber process-based methods are widely used for encapsulation of metal nanoparticles in SiO2, these time-consuming methods are not effective for coating metal microparticles with a uniform SiO2 layer of desired thickness. Herein, an ultrasound-assisted, interface-confined sol-gel method is proposed for fast encapsulation of metal microparticles in SiO2, and the encapsulation of Sn microparticles is chosen as an example to illustrate its feasibility. The proposed method involves covering metal microparticles with liquid films that contain water, alcohol, surfactant (Span-80) and catalyst (NH4F) and then ultrasonically dispersing these particles into cyclohexane, where tetraethylorthosilicate (TEOS) is added. To ensure the hydrolysis-condensation reactions of TEOS occurring at the particle-cyclohexane interface so that the formed SiO2 is coated on the particles, the microparticles should be well dispersed into cyclohexane with the liquid films being not broken away from their surfaces. It is found that the assistance of probe sonication and the addition of surfactant are crucial to achievement of a good dispersion of metal microparticles in cyclohexane. And using high-viscosity alcohol (namely glycerol), controlling the volume ratio of water to alcohol and the amount of water, and choosing a suitable ultrasonic power are essential for preventing the formation of free SiO2 (namely SiO2 that is not coated on the particles), which is a result that the liquid films escape from the particle surfaces under ultrasonic cavitation. Our results have also revealed that the thickness of SiO2 layer can be adjusted by changing the reaction time or the total amount of water. In particular, the thickness of SiO2 layer can be easily raised by simply repeating the encapsulation procedure. Compared with the traditional Stoˇber process-based methods, the proposed method is time-saving (reaction time: about 30 min vs. more than 12 h) and extremely effective for coating microparticles with a continuous, uniform SiO2 layer of desired thickness.

The Combination of MoS2/WO3 and Its Adsorption Properties of Methylene Blue at Low Temperatures.

It was found previously that neither monomer MoS2 nor WO3 is an ideal material for the adsorption of organic dyes, while MoS2/WO3 composites synthesized by a two-step hydrothermal method have outstanding adsorption effects. In this work, the chemical state of each element was found to be changed after combination by X-ray photoelectron spectroscopy analysis, which lead to their differences in adsorption performance. Moreover, the adsorption test of methylene blue on MoS2/WO3 composites was carried out under a series of temperatures, showing that the prepared composites also had appreciable adsorption rates at lower temperatures. The adsorption process could be well described by the Freundlich isothermal model and the pseudo-second order model. In addition, the particle-internal diffusion model simulation revealed that the internal diffusion of the particles played an important role in the whole adsorption process.

Aging Mechanism of a Diatomite-Modified Asphalt Binder Using Fourier-Transform Infrared (FTIR) Spectroscopy Analysis.

In this paper, Fourier-transform infrared (FTIR) spectroscopy was used to evaluate the effects of diatomite on aging properties of an asphalt binder. The modified asphalts included 5%, 10%, and 15% diatomite, and were prepared in the laboratory. The changes in functional groups of asphalt were employed to investigate the aging mechanisms of the modified and control asphalts. Effects of diatomite on the anti-aging properties of asphalt were analyzed via the changes in intensity of the absorption peaks. Results showed that there were no new functional groups generated after diatomite mixing with asphalt. This indicated that the process of diatomite modification was just physical mixing. Furthermore, parts of saturates and aromatics were volatilized in the aging process of modified asphalt. Polar molecules reacted with oxygen in aging. Meanwhile, carbonyl (C=O) and sulfoxide (S=O) were also generated. The aging resistance of modified asphalt was the best when the diatomite content was 10%. The work of this paper may provide a new perspective to evaluate asphalt aging.