The eutectic ionic liquid （EIL） tetraethyl ammonium bromide-malonic acid （TEAB-Mal） was synthesized, with its structure characterized by the FT-IR spectroscopy and the 1H NMR spectrometry. The performance for remo...The eutectic ionic liquid （EIL） tetraethyl ammonium bromide-malonic acid （TEAB-Mal） was synthesized, with its structure characterized by the FT-IR spectroscopy and the 1H NMR spectrometry. The performance for removal of basic nitrogen compounds by EIL was studied using coker diesel as the feedstock. Experimental results showed that the EIL （TEAB-Mal） exhibited a good denitrogenation performance, leading to a 93.6% of basic N-removal efficiency under reaction conditions covering： a temperature of 30 ℃, an EIL to oil mass ratio of 1：1, an extraction time of 30 min, and a settling time of 120 min, while the basic nitrogen content in diesel dropped from 580 μg/g to 37 gg/g. In addition, the efficiency for extraction of basic N-compounds could still reach 62.9% at am EIL/oil mass ratio of 1：7 after four recycles of the EIL.展开更多
The undigested nitrogenous fraction entering the hindgut of chickens is further metabolized by microbiota present producing volatile basic metabolites including amines and ammonia(NH3).Ammonia increases pH and may res...The undigested nitrogenous fraction entering the hindgut of chickens is further metabolized by microbiota present producing volatile basic metabolites including amines and ammonia(NH3).Ammonia increases pH and may result in overgrowth of Clostridium perfringens further producing toxic metabolites that cause dysbacteriosis or necrotic enteritis(NE).There are few reports in chickens examining the production and concentration of nitrogenous metabolites in the hindgut.A Berthelot reaction using an automated flow,reaction and spectrophotometric instrumentation to detect volatile basic nitrogen in the form of NH3 from cecal contents was carried out.In the Berthelot reaction,NH3 in the sample is chlorinated to monochloramine using dichloroisocyanuric acid that then reacts with salicylate to form 5-aminosalicylate which is stable under alkaline conditions(pH 12 to 13).After oxidation and oxidative coupling,a coloured complex is formed that can be measured at 660 nm.Cecal contents were collected and pooled from 2 birds per pen with 48 pens total in each of 3 experiments and stored in sealed containers at-20℃prior to analysis.Experiment 1 compared samples collected from birds fed either no meat and bone meal(MBM)or 6%MBM from d 0 to 14,and samples collected from birds fed either no MBM or 5%MBM from d 14 to 42.All birds were challenged with Eimeria on d 9 and C.perfringens on d 14 and 15.Experiment 2 compared cecal contents from birds fed either 0.5%or 0.9%calcium(Ca),and Exp.3 compared unchallenged with NE challe nge on d 16 and 29.Results demonstrated an increase(P<0.05)in cecal NH3 as a result of feeding MBM or high dietary Ca with a corresponding increase in pH.Birds experimentally challenged with NE had lower cecal NH3 and lower pH on d 16 but not d 29 compa red to unchallenged controls.It was concluded that the Berthelot method using Skalar instrumentation equipment is suitable to measure the concentration of volatile nitrogen as NH3 in cecal contents of chickens.展开更多
Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficientl...Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficiently accomplished from the key intermediate(S)-6 with three contiguous stereocenters in 5 steps and the synthetic 1 induced G2/M-phase cell cycle arrest of HT29 cells and apoptosis of HL60 and NB4 cells by activation of caspase-3 and degradation of PARP.(S)-6,bearing three contiguous chiral centers,was efficiently constructed by a novel Nazarov cyclization reaction containing basic nitrogen,which was less developed,primarily due to the incompatibility of basic nitrogen under acidic reaction conditions.This reaction allows a wide range of pentadienone substrates containing basic nitrogen to undergo Nazarov cyclization in a single regioselective and diastereoselective manner and is capable of generating three stereocenters simultaneously.Furthermore,the mechanism of the Nazarov cyclization and the origin of the regio-and diastereoselectivity were elucidated by DFT calculations and deuteration experiments,providing valuable insights into the reaction and serving as a guide for future applications involving substrates containing basic nitrogen.展开更多
Nitrogen oxides （NOx） emission during the regeneration ofcoked fluid catalytic cracking （FCC） catalysts is an en- vironmental issue. In order to identify the correlations between nitrogen species in coke and diffe...Nitrogen oxides （NOx） emission during the regeneration ofcoked fluid catalytic cracking （FCC） catalysts is an en- vironmental issue. In order to identify the correlations between nitrogen species in coke and different nitrogen- containing products in tail gas, three coked catalysts with multilayer structural coke molecules were prepared in a fixed bed with model compounds （o-xylene and quinoline） at first. A series of characterization methods were used to analyze coke, including elemental analysis, FT-IR, XPS, and TG-MS. XPS characterization indicates all coked catalysts present two types of nitrogen species and the type with a higher binding energy is related with the inner part nitrogen atoms interacting with acid sites. Due to the stronger adsorption ability on acid sites for basic nitrogen compounds, the multilayer structural coke has unbalanced distribution of carbon and ni- trogen atoms between the inner part and the outer edge, which strongly affects gas product formation. At the early stage of regeneration, oxidation starts from the outer edge and the product NO can be reduced to N2 in high CO concentration. At the later stage, the inner part rich in nitrogen begins to be exposed to 02. At this period, the formation of CO decreases due to lack of carbon atoms, which is not beneficial to the reduction of NO. There- fore, nitrogen species in the inner part of multilayer structural coke contributes more to NOx formation. Based on the multilayer structure model of coke molecule and its oxidation behavior, a possible strategy to control NOx emission was discussed merely from concept.展开更多
基金the financial support from the Doctoral Funds of Liaoning Provincial Natural Science Foundation(201601323)
文摘The eutectic ionic liquid （EIL） tetraethyl ammonium bromide-malonic acid （TEAB-Mal） was synthesized, with its structure characterized by the FT-IR spectroscopy and the 1H NMR spectrometry. The performance for removal of basic nitrogen compounds by EIL was studied using coker diesel as the feedstock. Experimental results showed that the EIL （TEAB-Mal） exhibited a good denitrogenation performance, leading to a 93.6% of basic N-removal efficiency under reaction conditions covering： a temperature of 30 ℃, an EIL to oil mass ratio of 1：1, an extraction time of 30 min, and a settling time of 120 min, while the basic nitrogen content in diesel dropped from 580 μg/g to 37 gg/g. In addition, the efficiency for extraction of basic N-compounds could still reach 62.9% at am EIL/oil mass ratio of 1：7 after four recycles of the EIL.
文摘The undigested nitrogenous fraction entering the hindgut of chickens is further metabolized by microbiota present producing volatile basic metabolites including amines and ammonia(NH3).Ammonia increases pH and may result in overgrowth of Clostridium perfringens further producing toxic metabolites that cause dysbacteriosis or necrotic enteritis(NE).There are few reports in chickens examining the production and concentration of nitrogenous metabolites in the hindgut.A Berthelot reaction using an automated flow,reaction and spectrophotometric instrumentation to detect volatile basic nitrogen in the form of NH3 from cecal contents was carried out.In the Berthelot reaction,NH3 in the sample is chlorinated to monochloramine using dichloroisocyanuric acid that then reacts with salicylate to form 5-aminosalicylate which is stable under alkaline conditions(pH 12 to 13).After oxidation and oxidative coupling,a coloured complex is formed that can be measured at 660 nm.Cecal contents were collected and pooled from 2 birds per pen with 48 pens total in each of 3 experiments and stored in sealed containers at-20℃prior to analysis.Experiment 1 compared samples collected from birds fed either no meat and bone meal(MBM)or 6%MBM from d 0 to 14,and samples collected from birds fed either no MBM or 5%MBM from d 14 to 42.All birds were challenged with Eimeria on d 9 and C.perfringens on d 14 and 15.Experiment 2 compared cecal contents from birds fed either 0.5%or 0.9%calcium(Ca),and Exp.3 compared unchallenged with NE challe nge on d 16 and 29.Results demonstrated an increase(P<0.05)in cecal NH3 as a result of feeding MBM or high dietary Ca with a corresponding increase in pH.Birds experimentally challenged with NE had lower cecal NH3 and lower pH on d 16 but not d 29 compa red to unchallenged controls.It was concluded that the Berthelot method using Skalar instrumentation equipment is suitable to measure the concentration of volatile nitrogen as NH3 in cecal contents of chickens.
基金supported by the National Natural Science Foundation of China(Nos.81725021,81903461)the National Key R&D Program of China(No.2022YFA1503200)the Natural Science Foundation of Hubei Province(No.ZRMS2023000340)。
文摘Asperfilasin A(1),featuring a unique 5/5 cyclopenta[c]pyrrol-one bicyclic core,represents a newly discovered skeletal cytochalasan isolated from Aspergillus flavipes.The enantioselective total synthesis was efficiently accomplished from the key intermediate(S)-6 with three contiguous stereocenters in 5 steps and the synthetic 1 induced G2/M-phase cell cycle arrest of HT29 cells and apoptosis of HL60 and NB4 cells by activation of caspase-3 and degradation of PARP.(S)-6,bearing three contiguous chiral centers,was efficiently constructed by a novel Nazarov cyclization reaction containing basic nitrogen,which was less developed,primarily due to the incompatibility of basic nitrogen under acidic reaction conditions.This reaction allows a wide range of pentadienone substrates containing basic nitrogen to undergo Nazarov cyclization in a single regioselective and diastereoselective manner and is capable of generating three stereocenters simultaneously.Furthermore,the mechanism of the Nazarov cyclization and the origin of the regio-and diastereoselectivity were elucidated by DFT calculations and deuteration experiments,providing valuable insights into the reaction and serving as a guide for future applications involving substrates containing basic nitrogen.
基金Supported by the National Natural Science Foundation of China(21476263)the National Natural Science Foundation for Young Scholars(21206198)
文摘Nitrogen oxides （NOx） emission during the regeneration ofcoked fluid catalytic cracking （FCC） catalysts is an en- vironmental issue. In order to identify the correlations between nitrogen species in coke and different nitrogen- containing products in tail gas, three coked catalysts with multilayer structural coke molecules were prepared in a fixed bed with model compounds （o-xylene and quinoline） at first. A series of characterization methods were used to analyze coke, including elemental analysis, FT-IR, XPS, and TG-MS. XPS characterization indicates all coked catalysts present two types of nitrogen species and the type with a higher binding energy is related with the inner part nitrogen atoms interacting with acid sites. Due to the stronger adsorption ability on acid sites for basic nitrogen compounds, the multilayer structural coke has unbalanced distribution of carbon and ni- trogen atoms between the inner part and the outer edge, which strongly affects gas product formation. At the early stage of regeneration, oxidation starts from the outer edge and the product NO can be reduced to N2 in high CO concentration. At the later stage, the inner part rich in nitrogen begins to be exposed to 02. At this period, the formation of CO decreases due to lack of carbon atoms, which is not beneficial to the reduction of NO. There- fore, nitrogen species in the inner part of multilayer structural coke contributes more to NOx formation. Based on the multilayer structure model of coke molecule and its oxidation behavior, a possible strategy to control NOx emission was discussed merely from concept.
