Fast assembly of MXene hydrogels by interfacial electrostatic interaction for supercapacitors.

A simple and fast method for preparing MXene hydrogels is proposed by introducing protonated thionine molecules into a MXene dispersion through electrostatic interaction. Such a 3D hydrogel effectively suppressed restacking and oxidation, and enlarged the surface utilization of the MXene, producing an improved specific capacitance of 163 F g-1 at 1 A g-1 and excellent stability when used as an electrode material for supercapacitors.

Fe3O4-Encapsulating N-doped porous carbon materials as efficient oxygen reduction reaction electrocatalysts for Zn-air batteries.

Fe3O4 nanoparticle-encapsulating N-doped porous carbon was synthesized. Owing to the large specific surface area, hierarchical porous structure, and sufficient number of active sites from the graphitic carbon wrapped Fe3O4 NPs as well as the joint effect with Fe-Nx moieties, the as-prepared 2D-Fe3O4@FeNC-700 electrocatalyst exhibits exceptional performance in Zn-air batteries.

[Study of pyrolysates of flue-cured tobacco leaves and stems].

To further understand the effect of tobacco stems in tobacco blend, a detailed comparative study of chemical components of tobacco leaves and stems before and after combustion was carried out. Pyrolysis of tobacco leaves and stems was carried out by a CDS Pyrolyser 2000 coupled to a Finnigan 8000(TOP) Gas Chromatograph and a Voyager Mass Spectrometer (GC-MS). A modified apparatus of pyrolysis was used to emulate the behavior of combustion of cigarette. A set of pyrolysis conditions was also developed that approximated those occurring in the pyrolysis region of the burning cigarette. The conditions included heating the sample at 20 degrees C/ms from 30 degrees C to 300 degrees C, 600 degrees C and 900 degrees C in air, and their pyrolysates were analyzed by GC-MS. The results indicated that the values of routine chemical constituents in tobacco leaves and stems were obviously different. The pyrolysates belonged to numerous classes of compounds such as hydrocarbons, alcohols, phenols, aldehydes, ketones, nitriles, alkaloids etc. The kinds of pyrolysates of tobacco leaves and stems were positively related to the pyrolysis temperature levels. On the other hand, at the same temperature level, the types of the pyrolysates from the tobacco leaves were much more than those from the tobacco stems.

[Study of pyrolysates of beta-carotene in tobacco].

Relationships between tobacco compounds and smoke products are complex and often difficult to unravel. Pyrolysis experiments have frequently been used to establish such relationships. The relevance of pyrolysis experiments to the behavior of tobacco constituent in a burning cigarette was studied. A set of pyrolysis conditions has been developed to study the effect of thermal degradation of beta-carotene to the cigarette smoke quality, and the conditions was approximated to those occurring in the pyrolysis region of the burning cigarette. The pyrolysates of beta-carotene were investigated in air, 10% O2 (in N2) and N2 at three temperature levels of 300 degrees C, 600 degrees C and 900 degrees C, respectively. The pyrolysates were adsorbed by solid-phase microextraction (SPME) and then analyzed by gas chromatography/mass spectrometry (GC/ MS). Under the different conditions, the major pyrolysates from beta-carotene are hydrocarbon compounds such as toluene, p-xylene, 1, 2, 3, 4-tetrahydro-1, 1, 6-trimethyl-naphthalene and 2, 7-dimethyl-naphthalene, and some important flavors existing in cigarette smoke such as isophorone, 2, 6, 6-trimethyl-1-cyclohexene-1-carboxaldehyde, beta-ionone and 5, 6, 7, 7a-tetrahydro-4, 4, 7 a-trimethyl-2 (4H)-benzofuranone. The amount of these pyrolysates alters with the change of pyrolysis temperature levels and the concentration of oxygen.