Micellization behavior of ionic liquid surfactants with two hydrophobic tail chains in aqueous solution

Solidifying dust suppressant based on modified chitosan and experimental study on its dust suppression performance

In view of the fugitive dusts caused by wind disturbance and material handling in coal bunkers, surface plants, and open-air coal stocking yards of coal businesses, the solidifying dust suppressant based on modified chitosan is synthesized and prepared through the chemical modification of –NH2 with chitosan as a raw material and –NH2 was replaced by –CH2CH(OH)CH2N+(CH3)CI− through the technique of Fourier transform infrared spectroscopy. According to viscosity experiment results, the viscosity of the modified solidifying dust suppressant increased significantly. The coal particles suppressed by the dust suppressant as observed with a 50,000X scanning electron microscope were coagulated together, which indicated very good cohesion effect. In addition, wind erosion resistance experiment was conducted to analyze the wind erosion rate of coal powders before and after sprayed with the suppressant at different wind speeds, which indicated that the dust suppressant can effectively prevent fugitive dusts at a wind speed of 17 m/s.

A Fragmentation Study on Four Unusual Secoiridoid Trimers, Swerilactones H-K, by Electrospray Tandem Mass Spectrometry

Swerilactones H-K (1-4) as four unprecedented secoiridoid trimers represent a new type of natural product, which has attracted much interest of natural chemists due to their novel skeletons and promising bioactivity. In order to well understand their MS fragmentation behaviors, they were investigated by electrospray ionization ion-trap time-of-flight multistage product ion mass spectrometry (ESI-IT-TOF-MS ⁿ ) for the first time. The protonated molecules ([M+H]⁺) of swerilactones J and K, and deprotonated molecules ([M-H]^-) of swerilactones H, J and K were readily observed in the conventional single-stage mass spectra (MS); however only the [M+Cl]^- ion for swerilactone I was obtained in negative mode. Based on the MS ⁿ study, the fragmentation pathways of swerilactones H and I in negative mode, and swerilactones J and K in both positive and negative modes were proposed. The neutral losses of H₂O, CO, CO₂ and C₂H₄O moieties are the particular elimination from the precursor ions due to the presence of hydroxyl, δ-lactone and 1-O-ethyl moieties in their structures, of which the retro-Diels-Alder cleavage was the most particular dissociation. The fragment ions at m/z 341 and 291 in negative mode can be considered as the diagnostic ions for secoiridoid trimers. This investigation will provide valuable information for their fast characterization from complicated natural mixtures and extensive understanding their structural architectures.