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Dental calculus is a potential material that can be used for assessing chronic exposure to trace heavy metals in oral cavity as it is a long-term reservoir. The aim of this study was to investigate the correlation between dental calculus copper levels and risk of oral submucous fibrosis (OSF) due to chewing dried areca-nut quids in Mainland China. This study included 34 OSF (grade 1) sufferers with dried areca-nut quids chewing as the patient group and 23 healthy individuals without areca-nut chewing as the control group. The dental calculus sample was obtained from all 57 participants and evaluated by inductively coupled plasma mass spectrometry (ICP-MS) for dental calculus level of copper. This work revealed that the mean copper level of dental calculus was significantly higher in OSF (grade 1) sufferers with areca-nut chewing than those in healthy individuals without areca-nut chewing (p 0.001). This work provided an evidence to support that there may be a positive correlation between elevated levels of copper in dental calculus caused by chewing dried areca-nut quids and an increased risk of developing OSF in Mainland China.

A chiral phosphoric acid-catalyzed asymmetric transfer hydrogenation of 3-trifluoromethylthioquinolines has been successfully developed, providing direct and facile access to chiral 2,3-disubstituted 1,2,3,4-tetrahydroquinoline derivatives containing a stereogenic trifluoromethylthio group with up to 99% enantioselectivity.

Laser-induced breakdown plasma was used for gas temperature measurement based on the residual energy of a laser pulse defined as the laser energy detected in the beam path as well as plasma emissions. Gas mixtures with different compositions ( O 2 / N 2 , O 2 / C O 2 , and O 2 / N 2 / C O 2 ) were used to simulate the main components of combustion products at different temperatures. First, the correlation of residual energy and gas temperature was investigated, which showed that the residual energy increased with an increase in the gas temperature. The results showed that it also relates to the gas composition, which would affect the characteristics of laser-induced plasma. Then the spectral emission ratio of the plasma (O/N, O/C, and C/N) was obtained simultaneously to correct the compositional effect on the temperature measurement. Finally, the gas temperature with different components can be obtained by the equation coupled with the gas temperature, residual energy, and gas composition. The corrected temperature is consistent with that obtained by thermocouple and the gas temperature measurement error is less than 3.5% in the range from 309 K to 548 K.

The work concerned the ignition characteristics and alkali metals (Na and K) release behavior during the combustion process of single coal particles with the additional different forms of K contents. The measurement was performed in O2/N2 and O2/CO2 atmospheres. The high-speed camera was used to investigate the influences from different forms of potassium (KCl and K2CO3) on the ignition characteristics, and the temporal release behaviors of alkali metals were obtained with the detection of atomic emission spectrum of alkali metals (Na and K). The sample with additive of KCl has the higher emission intensity and lower ignition delay than that the sample with additive of K2CO3. The substituting CO2 for N2 had more effect for KCl than for K2CO3 addition in the initial stage of volatile combustion, but it reversed as burning progressed. The comparison of the gas phase temperature during the ignition with the appearance moment of the K emission could be further illustrated that the main reason affecting the release of atomic alkali metals was the presence of different form of potassium, which affected the liberation and diffusion rate of the volatiles.

A chiral phosphoric acid-catalyzed asymmetric transfer hydrogenation of 3-trifluoromethylthioquinolines has been successfully developed, providing direct and facile access to chiral 2,3-disubstituted 1,2,3,4-tetrahydroquinoline derivatives containing a stereogenic trifluoromethylthio group with up to 99% enantioselectivity.

A hexaazatriphenylene (HAT) derivative (compound 1) that bears four n-octyl chains and two thienyl groups was designed and synthesized. Further light-induced oxidation coupling reaction led to thienyl-fused compound 2. Their photophysical and electrochemical properties and self-assembly behavior have been investigated by UV/Vis, fluorescence, and (1)H NMR spectroscopies, cyclic voltammetry (CV), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD). Although the difference in compounds 1 and 2 only lie in one single bond that connects the two thienyl segments, they displayed remarkably different properties, revealing an interesting structure-property relationship.