Seasonal variation of atmospheric elemental carbon aerosols at Zhongshan Station, East Antarctica

Elemental carbon (or black carbon) (EC or BC) aerosols emitted by biomass burning and fossil fuel combustion could cause notable climate forcing. Southern Hemisphere biomass burning emissions have contributed substantially to EC deposition in Antarctica. Here, we present the seasonal variation of EC determined from aerosol samples acquired at Zhongshan Station (ZSS), East Antarctica. The concentration of EC in the atmosphere varied between 0.02 and 257.81 ng·m−3 with a mean value of 44.87±48.92 ng·m−3. The concentration of EC aerosols reached its peak in winter (59.04 ng·m−3) and was lowest (27.26 ng·m−3) in summer. Back trajectory analysis showed that biomass burning in southern South America was the major source of the EC found at ZSS, although some of it was derived from southern Australia, especially during winter. The 2019–2020 Australian bush fires had some influence on EC deposition at ZSS, especially during 2019, but the contribution diminished in 2020, leaving southern South America as the dominant source of EC

Acetic Acid-Catalyzed (3 + 2) Cyclization of 2‑Aroyl-3-aryl-1,1-dicyanocyclopropanes with Arylhydrazines: To <i>trans</i>-4-Dicyanomethyl-1,3,5-triaryl-4,5-dihydropyrazoles

Acetic acid-catalyzed (3 + 2) cyclization reaction of substituted 2-aroyl-3-aryl-1,1-dicyanocyclopropanes with arylhydrazines was investigated for the efficient synthesis of 4-dicyanomethyl-1,3,5-triaryl-4,5-dihydropyrazoles in good yields, in which 4,5-double substituents are predominantly trans selective. This approach included the consecutive condensation, ring opening, and double nucleophilic cyclization reaction

ZnCl₂‑Promoted Three-Component Reaction of 2‑Aminochromenones, Aromatic Aldehydes, and Quinone Monoketals: Access to 5,6-Dihydro-12<i>H</i>‑chromeno[2,3‑<i>c</i>]isoquinolin-12-one Derivatives

A three-component reaction of 2-amino-4H-chromen-4-ones, aromatic aldehydes, and 4,4-dialkoxycyclohexa-2,5-dien-1-ones for the concise synthesis of chromeno­[2,3-c]­dihydro­isoquinoline derivatives has been investigated. This reaction involved consecutive ZnCl2-promoted Micheal addition and intramolecular Friedel–Crafts alkylation. This synthetic protocol offered several advantages, including the readily accessible starting materials, good functional group tolerance, and simplicity of operation. Additionally, the structures of products obtained were determined based on X-ray diffraction studies

Physiological effects of autotoxicity due to DHAP stress on Picea schrenkiana regeneration.

Picea Schrenkiana as one of the most important zonal vegetation was an endemic species in Middle Asia. Natural regeneration of P. Schrenkiana is a long existing problem troubling scientists. The autotoxicity of 3,4-dihydroxy-acetophenone (DHAP) was found to be a causative factor causing the failure of P. Schrenkiana natural regeneration. The effects of concentrations of DHAP treatment on the viability of root cell, activities of antioxidant enzymes and levels of P. Schrenkiana phytohormones were performed to disclose the physiological mechanism of DHAP autotoxicity. It was observed that high concentration of DHAP could inhibit the seed germination and seedling growth, but had a hormesis at low concentrations. Analyses showed that the root cells significantly lost their viability treated with high DHAP. The enzymes activities of seedlings were significantly stimulated by the treatment of 0.5 mM DHAP to give a transient increase and then decrease as DHAP concentration increased to 1.0 mM except for GR (glutathione reductase) in which DHAP treatment had little effect on its activity. Comparing with the control, an increase in the levels of phytohormones ZT (zeatin), GA3 (gibberellic acid) and IAA (indole acetic acid) was induced by the treatment of DHAP at low concentrations (0.1-0.25 mM), but the significant deficiency was found treated by high concentrations (0.5-1.0 mM). In addition, the ABA (abscisic acid) level increased in all experimental observations. These results suggested that DHAP significantly affected indices of growth and physiology, and provided some new information about different effect in P. Schrenkiana treated with DHAP