Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic cataly...Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic catalysts prepared,Pt-Pb/SiO2 is the best and nitrobenzene could be converted to paminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at110 ℃ under 5 MPa CO2 and 0.2 MPa H2.展开更多
p-Aminophenol （PAP）, a typical amphoteric compound, has been widely used as raw chemical material and important interrnediate in various fields. To study on the recovery of PAP, an experimental comparison of the ads...p-Aminophenol （PAP）, a typical amphoteric compound, has been widely used as raw chemical material and important interrnediate in various fields. To study on the recovery of PAP, an experimental comparison of the adsorption and desorption properties of PAP onto three types of hyper-cross-linked resins in aqueous solutions was performed. This paper focuses on the static equilibrium adsorption and desorption behaviors, the adsorption thermodynamics, the column dynamic adsorption and desorption, and other influencing factors of adsorption, such as temperature and pH values. All the isothermal data fit well to the Freundlich model. The capacity of equilibrium adsorption for PAP on NG-10 is the highest within the temperature range 288K-318K, which may greatly contribute to the advantage in specific surface area, especially the micropore area, of the adsorbent. While in the desorption experiments, NG-9 achieved relative well regeneration efficiency whether by ethanol or by 4% hydrochloric acid. Furthermore, the results of column tests and field applications were also proved that NG-9 was an effective sorbent for the reclamation PAP from wastewater.展开更多
In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic propert...In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.展开更多
MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using...MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using MgAPO-5 as acidic supports,bifunctional Pt/MgAPO-5 catalysts were prepared for hydrogenation of nitrobenzene to p-aminophenol (PAP).The results showed that the MgO/Al2O3 ratios influenced the Mg content and the acidity of MgAPO-5 samples,thereby greatly affecting the catalytic performance of Pt/MgAPO-5 catalysts.The selectivity to PAP over Pt/MgAPO-5 was dependent on the amount of strong acid sites of MgAPO-5.When the MgO/Al2O3 molar ratio was 0.5,the synthesized MgAPO-5 sample exhibited the largest amount of strong acid and a highest PAP yield of 41.1% was achieved over Pt/MgAPO-5 catalyst.展开更多
In order to well arrange active sites and avoid byproducts, the reasonable structured carrier nanocatalyst plays a crucial role in high catalytic performance, but still remains a challenge. Herein, the layered CuNi-Cu...In order to well arrange active sites and avoid byproducts, the reasonable structured carrier nanocatalyst plays a crucial role in high catalytic performance, but still remains a challenge. Herein, the layered CuNi-Cu_(2)O/NiAlO_(x) nanosheets have been constructed through hydrothermal synthesis followed by calcination and H_(2) reduction treatment process. The in-situ formed CuNi nanoalloys (NAs) and nano-Cu_(2)O were evenly distributed on the bilateral surface of layered NiAlOx nanosheets. Based on the planar structure of nanosheet, the synergy between catalytic active CuNi NAs and photocatalytic active nano-Cu_(2)O endows CuNi-Cu_(2)O/NiAlO_(x) nanosheets with rapid conversion efficiency for catalyzing p-nitrophenol (p-NP, 14 mg·L^(−1)) to p-aminophenol (p-AP) in 32 s with the reaction rate constant k up to 0.1779 s−1, and no obvious performance decay can be observed even over 27 cycles. Moreover, high concentration of p-NP at 10 and 20 g·L^(−1) could be reduced to p-AP within 14 and 20 min, respectively. Such designed nanoalloy/bimetal-oxide heterostructure can provide a solution for rapid conversion of aminoaromatics from nitroaromatics wastewater even at a large concentration range.展开更多
Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable...Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable and can be reused for at least 4 times with only slight decrease in activity.展开更多
Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the deg...Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the degradation of pollutants from the stand-point of solar energy utilization, e.g. TiO<sub>2</sub>, the photoinduced holes with high oxidationpotential, may be used as strong oxidant to decompose a large number of展开更多
An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were...An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were used to evaluate the electrocatalytic activity of the proposed electrode by choosing p-aminophenol （p-AP） as a model compound. Both at a bare carbon paste electrode （CPE） and the M-CPE, p-AP yielded a pair of redox peaks in 0.1 mol·L^-1 phosphate buffer solution （PBS, pH 7.0）. At the CPE, the peak-to-peak potential separation （AEp） was 0.233 V, while at the M-CPE the AEp was decreased to 0.105 V. Furthermore, the current response to p-AP at the M-CPE was 10.2 times of that at the CPE by DPV. The electron transfer rate constant （ks） ofp-AP at the M-CPE was 13.3 times of that at the CPE. Under the optimal condition, a linear dependence of the catalytic current versus p-AP concentration was obtained in the range of 2.0× 10^- 6 to 3.0× 10^- 4 mol·L^-1 with a detection limit of 6.0× 10^-7 mol·L^-1 by DPV. In addition, compared to other modified method the proposed electrode exhibited distinct advantages of simple prapartion, surface renewal, good reproducibility and good stability. It has been used to determine p-AP in simulated wastewater samples.展开更多
Aim: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline, deposits of amyloid beta and neurofibrillary tangles. Inflammation facilitated by microglia, the resident immune ce...Aim: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline, deposits of amyloid beta and neurofibrillary tangles. Inflammation facilitated by microglia, the resident immune cells of the brain, contribute to the pathogenesis of AD. Epidemiological data indicate that nonsteroidal anti-inflammatory drugs (NSAIDs), which are cyclooxygenase (COX) inhibitors, reduce the risk of developing AD when administered over the course of two or more years. The mechanisms underlying this protective effect are unknown. Acetaminophen (paracetamol), which is not effective as an inhibitor of COX in peripheral tissues, may provide similar protection without the adverse effects of chronic NSAID use. The beneficial effects of acetaminophen have been proposed to stem from its metabolites p-aminophenol and N-arachidonoylaminophenol (AM404), of which, AM404 possesses analgesic and antipyretic properties. The goal of this study was to compare the effects of acetaminophen and its metabolites on microglial immune function and to elucidate the molecular mechanisms engaged by these compounds. Methods: Lipopolysaccharide-stimulated BV-2 murine microglia were used as models. Microglial activation was monitored by their secretion of nitric oxide. Results: P-aminophenol and AM404 suppressed nitric oxide secretion from stimulated microglia more effectively than acetaminophen through pathways that were independent of COX inhibition, cannabinoid receptor type two (CB2) inhibition, and activation of transient receptor potential cation channel subfamily V member 1 (TRPV1). Conclusion: Since AM404 has been previously demonstrated to attenuate NF-kB activation, it is likely that the protective effects of acetaminophen against adverse microglia activation are mediated by its metabolites p-aminophenol and AM404 inhibiting this transcription factor.展开更多
文摘Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic catalysts prepared,Pt-Pb/SiO2 is the best and nitrobenzene could be converted to paminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at110 ℃ under 5 MPa CO2 and 0.2 MPa H2.
文摘p-Aminophenol （PAP）, a typical amphoteric compound, has been widely used as raw chemical material and important interrnediate in various fields. To study on the recovery of PAP, an experimental comparison of the adsorption and desorption properties of PAP onto three types of hyper-cross-linked resins in aqueous solutions was performed. This paper focuses on the static equilibrium adsorption and desorption behaviors, the adsorption thermodynamics, the column dynamic adsorption and desorption, and other influencing factors of adsorption, such as temperature and pH values. All the isothermal data fit well to the Freundlich model. The capacity of equilibrium adsorption for PAP on NG-10 is the highest within the temperature range 288K-318K, which may greatly contribute to the advantage in specific surface area, especially the micropore area, of the adsorbent. While in the desorption experiments, NG-9 achieved relative well regeneration efficiency whether by ethanol or by 4% hydrochloric acid. Furthermore, the results of column tests and field applications were also proved that NG-9 was an effective sorbent for the reclamation PAP from wastewater.
文摘In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.
基金supported by the National Basic Research Program of China (2010CB234602)the National Natural Science Foundation of China (20636030,20706011 & 20876033)+1 种基金the Basic Research Program of Tianjin (07JCZDJC00100)the Education Bureau of Hebei Province (2005005D)
文摘MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using MgAPO-5 as acidic supports,bifunctional Pt/MgAPO-5 catalysts were prepared for hydrogenation of nitrobenzene to p-aminophenol (PAP).The results showed that the MgO/Al2O3 ratios influenced the Mg content and the acidity of MgAPO-5 samples,thereby greatly affecting the catalytic performance of Pt/MgAPO-5 catalysts.The selectivity to PAP over Pt/MgAPO-5 was dependent on the amount of strong acid sites of MgAPO-5.When the MgO/Al2O3 molar ratio was 0.5,the synthesized MgAPO-5 sample exhibited the largest amount of strong acid and a highest PAP yield of 41.1% was achieved over Pt/MgAPO-5 catalyst.
基金This work was supported by the National Natural Science Foundation of China(Nos.21771140,51979194,and 51771138)We really appreciate the support by the state key laboratory of fine chemicals,Dalian University of Technology(No.KF 2001).
文摘In order to well arrange active sites and avoid byproducts, the reasonable structured carrier nanocatalyst plays a crucial role in high catalytic performance, but still remains a challenge. Herein, the layered CuNi-Cu_(2)O/NiAlO_(x) nanosheets have been constructed through hydrothermal synthesis followed by calcination and H_(2) reduction treatment process. The in-situ formed CuNi nanoalloys (NAs) and nano-Cu_(2)O were evenly distributed on the bilateral surface of layered NiAlOx nanosheets. Based on the planar structure of nanosheet, the synergy between catalytic active CuNi NAs and photocatalytic active nano-Cu_(2)O endows CuNi-Cu_(2)O/NiAlO_(x) nanosheets with rapid conversion efficiency for catalyzing p-nitrophenol (p-NP, 14 mg·L^(−1)) to p-aminophenol (p-AP) in 32 s with the reaction rate constant k up to 0.1779 s−1, and no obvious performance decay can be observed even over 27 cycles. Moreover, high concentration of p-NP at 10 and 20 g·L^(−1) could be reduced to p-AP within 14 and 20 min, respectively. Such designed nanoalloy/bimetal-oxide heterostructure can provide a solution for rapid conversion of aminoaromatics from nitroaromatics wastewater even at a large concentration range.
基金Financial support by the Major State Basic Resource Development Program(Grant No.2012CB224804)NSFC(Project Nos.21373054,21173052)+1 种基金the Natural Science Foundation of Shanghai Science and Technol-ogy Committee(No.08DZ2270500)Hui-Chun Chin and Tsung-Dao Lee Chinese Undergraduate Re-search Endowment(CURE).
文摘Au/TiO_(2) catalyst is firstly reported to be efficient in the hydrogenation of nitrobenzene to produce p-aminophenol with a high PAP selectivity of 81%and overall yield more than 63%.The catalyst is also quite stable and can be reused for at least 4 times with only slight decrease in activity.
文摘Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the degradation of pollutants from the stand-point of solar energy utilization, e.g. TiO<sub>2</sub>, the photoinduced holes with high oxidationpotential, may be used as strong oxidant to decompose a large number of
基金Project supported by the National Natural Science Foundation of China （No. 20675062） and the Natural Science Foundation of Shaanxi Province in China （No. 2004B20）.
文摘An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were used to evaluate the electrocatalytic activity of the proposed electrode by choosing p-aminophenol （p-AP） as a model compound. Both at a bare carbon paste electrode （CPE） and the M-CPE, p-AP yielded a pair of redox peaks in 0.1 mol·L^-1 phosphate buffer solution （PBS, pH 7.0）. At the CPE, the peak-to-peak potential separation （AEp） was 0.233 V, while at the M-CPE the AEp was decreased to 0.105 V. Furthermore, the current response to p-AP at the M-CPE was 10.2 times of that at the CPE by DPV. The electron transfer rate constant （ks） ofp-AP at the M-CPE was 13.3 times of that at the CPE. Under the optimal condition, a linear dependence of the catalytic current versus p-AP concentration was obtained in the range of 2.0× 10^- 6 to 3.0× 10^- 4 mol·L^-1 with a detection limit of 6.0× 10^-7 mol·L^-1 by DPV. In addition, compared to other modified method the proposed electrode exhibited distinct advantages of simple prapartion, surface renewal, good reproducibility and good stability. It has been used to determine p-AP in simulated wastewater samples.
文摘Aim: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline, deposits of amyloid beta and neurofibrillary tangles. Inflammation facilitated by microglia, the resident immune cells of the brain, contribute to the pathogenesis of AD. Epidemiological data indicate that nonsteroidal anti-inflammatory drugs (NSAIDs), which are cyclooxygenase (COX) inhibitors, reduce the risk of developing AD when administered over the course of two or more years. The mechanisms underlying this protective effect are unknown. Acetaminophen (paracetamol), which is not effective as an inhibitor of COX in peripheral tissues, may provide similar protection without the adverse effects of chronic NSAID use. The beneficial effects of acetaminophen have been proposed to stem from its metabolites p-aminophenol and N-arachidonoylaminophenol (AM404), of which, AM404 possesses analgesic and antipyretic properties. The goal of this study was to compare the effects of acetaminophen and its metabolites on microglial immune function and to elucidate the molecular mechanisms engaged by these compounds. Methods: Lipopolysaccharide-stimulated BV-2 murine microglia were used as models. Microglial activation was monitored by their secretion of nitric oxide. Results: P-aminophenol and AM404 suppressed nitric oxide secretion from stimulated microglia more effectively than acetaminophen through pathways that were independent of COX inhibition, cannabinoid receptor type two (CB2) inhibition, and activation of transient receptor potential cation channel subfamily V member 1 (TRPV1). Conclusion: Since AM404 has been previously demonstrated to attenuate NF-kB activation, it is likely that the protective effects of acetaminophen against adverse microglia activation are mediated by its metabolites p-aminophenol and AM404 inhibiting this transcription factor.
