Synthesis of Axially Chiral N-Arylindoles via Atroposelective Cyclization of Ynamides Catalyzed by Chiral Brønsted Acids.

In recent years, asymmetric catalysis of ynamides has attracted much attention, but these reactions mostly constructed central chirality, except for a few examples on the synthesis of axially chiral compounds which exclusively relied on noble-metal catalysis. Herein, a facile access to axially chiral N-heterocycles enabled by chiral Brønsted acid-catalyzed 5-endo-dig cyclization of ynamides is disclosed, which represents the first metal-free protocol for the construction of axially chiral compounds from ynamides. This method allows the practical and atom-economical synthesis of valuable N-arylindoles in excellent yields with generally excellent enantioselectivities.

Catalytic effect and mechanism of coexisting copper on conversion of organics during pyrolysis of waste printed circuit boards.

Pyrolysis is a promising technology for recycling organic materials from waste printed circuit boards (WPCBs). Nevertheless, the generated organic bromides are toxic and urgently needed to be removed. The coexisting copper (Cu) of WPCBs has potential performance on debromination.

In-situ debromination mechanism based on self-activation and catalysis of Ca(OH) during pyrolysis of waste printed circuit boards.

Completely and deeply removed bromide from waste printed circuit boards (WPCBs) is necessary due to their toxicity and carcinogenicity. To achieve this purpose, calcium hydroxide (Ca(OH)) as a debromination agent was added during pyrolysis process of WPCBs. The results showed that hydrogen bromide (HBr), 4-bromophenol, 2-bromophenol and 2,4-dibromophenol were the main bromide species in pyrolysis products.

Nitrogen Addition Exacerbates the Negative Effects of Low Temperature Stress on Carbon and Nitrogen Metabolism in Moss.

Global environmental changes are leading to an increase in localized abnormally low temperatures and increasing nitrogen (N) deposition is a phenomenon recognized worldwide. Both low temperature stress (LTS) and excess N induce oxidative stress in plants, and excess N also reduces their resistance to LTS. Mosses are primitive plants that are generally more sensitive to alterations in environmental factors than vascular species.

Physiological responses of two moss species to the combined stress of water deficit and elevated N deposition (II): Carbon and nitrogen metabolism.

Nitrogen (N) deposition levels and frequencies of extreme drought events are increasing globally. In efforts to improve understanding of plants' responses to associated stresses, we have investigated responses of mosses to drought under elevated nitrogen conditions. More specifically, we exposed subsp.

Toxic effects of erythromycin, ciprofloxacin and sulfamethoxazole exposure to the antioxidant system in Pseudokirchneriella subcapitata.

We tested antioxidant responses of the green microalga Pseudokirchneriella subcapitata exposed to different concentrations of the three antibiotics erythromycin (ETM), ciprofloxacin (CPF) and sulfamethoxazole (SMZ). Measurements included the level of lipid peroxidation, the total antioxidative capacity and three major antioxidant mechanisms: the ascorbate-glutathione cycle, the xanthophyll cycle and the enzyme activities of catalase (CAT), superoxide dismutase (SOD), guaiacol glutathione peroxidase (GPX) and glutathione-S-transferase (GST). Three antibiotics significantly affect the antioxidant system of P.

Toxic effects of erythromycin, ciprofloxacin and sulfamethoxazole on photosynthetic apparatus in Selenastrum capricornutum.

The effects of three antibiotics (erythromycin, ciprofloxacin and sulfamethoxazole) on photosynthesis process of Selenastrum capricornutum were investigated by determining a battery of parameters including photosynthetic rate, chlorophyll fluorescence, Hill reaction, and ribulose-1.5-bisphosphate carboxylase activity, etc. The results indicated that three antibiotics could significantly inhibit the physiological progress including primary photochemistry, electron transport, photophosphorylation and carbon assimilation.

Growth response and toxic effects of three antibiotics on Selenastrum capricornutum evaluated by photosynthetic rate and chlorophyll biosynthesis.

The effects of three types of antibiotics (erythromycin, ciprofloxacin and sulfamethoxazole) on the photosynthesis of freshwater algae, Selenastrum capricornutum Printz, were investigated by determining the growth rate, chloroplast pigments content, seven main precursors (including delta-aminolevulinic acid, porphobilinogen, uroporphyrinogen III, coproporphyrinogen III, protoporphyrin IX, Mg-proporphyrin IX and protochlorophyllide), and photosynthetic rate during chlorophyll biosynthesis. The antibiotics significantly decreased the growth rate, chlorophyll content, and photosynthetic rate. Erythromycin induced a decreasing effect at a concentration of 0.