Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible d...Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,temperature-programmed reduction of H2,temperature-programmed desorption of NH3,infrared spectroscopy of adsorbed pyridine,H2 chemisorption,nitrogen adsorption-desorption,scanning electron microscopy and thermogravimetric analysis were performed.Kinetics of n-C7 isomerization were investigated under various hydrogen and n-C7 pressures,and the effects of reaction conditions on catalytic performance were studied.The results showed that bi-and trimetallic catalysts exhibit better performance than monometallic catalysts for this reaction.For example,a maximum i-C7 selectivity（ 〉74%） and multibranched isomer selectivity（40%） were observed for Pt-Sn/HZSM5-HMS at 200 ℃.展开更多
To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepa...To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.展开更多
Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,...Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,we develop an advanced approach of surface gel conversion for synthesis of submicron-thick pure silica MFI(silicalite-1)zeolite membranes.Viscous gel is prepared by finely adjusting the precursor composition,enabling its reduced wettability.The unfavorable wetting of the support surface can effectively prevent gel penetration into alumina support voids.Aided by the seeds,the surface gel is directly and fully crystallized into an MFI zeolite membrane with minimal water steam.A membrane with a thickness of 500 nm is successfully acquired and it is free of visible cracks.Additionally,the as-synthesized membranes exhibit rapid and selective separation of hexane isomers by virtue of unprecedentedly high n-hexane permeance of 24.5×10^−7 mol m^−2 s^−1 Pa^−1 and impressive separation factors of 13.3-22.6 for n-hexane over its isomers.This developed approach is of practical interest for sustainable synthesis of high-quality zeolite membranes.展开更多
目的:探讨不同梯度浓度顺铂(CDDP)处理不同肺癌细胞后新发现的剪接因子SRSF7 m RNA异构体在同浓度CDDP处理后不同的细胞中的水平变化。方法:采用梯度浓度的CDDP处理肺癌细胞A549(8、18、24、32、40、48及56μmol/L)和H1299(12、24、36...目的:探讨不同梯度浓度顺铂(CDDP)处理不同肺癌细胞后新发现的剪接因子SRSF7 m RNA异构体在同浓度CDDP处理后不同的细胞中的水平变化。方法:采用梯度浓度的CDDP处理肺癌细胞A549(8、18、24、32、40、48及56μmol/L)和H1299(12、24、36、48、60、72及84μmol/L),处理24 h后提取总RNA,进行RT-PCR检测SRSF7 m RNA剪接异构体,并选取NCBI中未确定的异构体进行TA克隆后测序并分析鉴定异构体类型;用56μmol/L的CDDP处理人胚肾细胞293FT,宫颈癌细胞Ca Ski、Si Ha、C33A细胞24 h,提取总RNA后验证新发现的SRSF7 m RNA剪切异构体是否存在这些细胞中。结果:发现3种新的SRSF7 m RNA剪接异构体(分别标记为New1、New2及New3),在肺癌细胞A549、H1299,人胚肾细胞293FT,宫颈癌细胞Ca Ski、Si Ha、C33A细胞等多种肿瘤细胞中均存在,根据NCBI的预测New1,New2,New3异构体均为非编码蛋白的m RNA异构体,随着处理CDDP浓度的增加,其比例明显上升;而编码蛋白的m RNA异构体a和(或)b所占比例明显下降;同时SRSF7的总m RNA水平逐渐降低。结论:新发现的3种非编码的m RNA异构体的变化揭示细胞可能通过SRSF7自身的m RNA选择性剪接来应对DNA损伤。展开更多
1,3-偶极环加成反应有多种选择性,因此产物往往也是由多个异构体组成.天然产物青藤碱进行1,3-偶极环加成反应杂环化时,产物理论上有四个异构体,实验中只发现两个异构体.本文分析了青藤碱1,3-偶极环加成反应中的选择性,再根据产物的1 H ...1,3-偶极环加成反应有多种选择性,因此产物往往也是由多个异构体组成.天然产物青藤碱进行1,3-偶极环加成反应杂环化时,产物理论上有四个异构体,实验中只发现两个异构体.本文分析了青藤碱1,3-偶极环加成反应中的选择性,再根据产物的1 H NMR、13C NMR、NOESY相关谱、电子效应、空间效应的分析,结合理论计算和软件模拟,最终确定了所得两种产物异构体-1和异构体-2的构型.本文的推定方法,在判定具有类似电子效应和空间效应的1,3-偶极环加成反应产物结构时,能起到一定的借鉴作用.展开更多
In this work, the structures of a pair of isomers were identified. And we showed the ability of the selective 1D version, performed the most common NMR experiments including the 1D-HMBC and GOESY experiments, to deter...In this work, the structures of a pair of isomers were identified. And we showed the ability of the selective 1D version, performed the most common NMR experiments including the 1D-HMBC and GOESY experiments, to determine the isom^ric composition that were found in the production process of roflumilast. The experimental results proved that this method would be even more time saving and could get more reliable results.展开更多
In order to compare the potential selectivity of R-（-）-DM-phencynonate hydrochloride with its racemate （±）-DM- phencynonate hydrochloride on acetylcholine muscarinic receptor subtypes, the five human acetylch...In order to compare the potential selectivity of R-（-）-DM-phencynonate hydrochloride with its racemate （±）-DM- phencynonate hydrochloride on acetylcholine muscarinic receptor subtypes, the five human acetylcholine muscarinic receptor subtypes （M1- M5） （CHO-hml-5R） were cloned and expressed in Chinese hamster ovary （CHO-K1） cell line. The specific mRNAs of the five acetylcholine muscarinic receptor subtypes were detected by the reverse transcription-polymerase chain reaction （RT-PCR） method, demonstrating the definite expression of muscarinic receptor subtype genes （CHO-hml-5R）. The affinity and saturability of different muscarinic receptor subtypes to [^3H] N-methylscopolamine （[^3H]-NMS） were obtained by radioligand binding assay. Equilibrium binding assay revealed that the maximum binding capacity of [^3H]-NMS （Bmax value） to CHO-hml-5R were 40.22±3.23, 24.53±4.11, 29.65±2.65, 25.41±2.46, 32.78±4.81 pmol/mg·protein, respectively. Kd values of [^3H]-NMS to muscarinic receptors M1 to M5 were 0.97±0.22, 1.16±0.14, 0.99±0.06, 0.56±0.08, 1.12±0.06 nM, respectively. R-（-）-DM- phencynonate hydrochloride was found to block the M4 receptor with a much higher potency （pD2 = 7.48） than those displayed on M1 （pD2 = 6.20）, M2 （pD2 = 5.99）, M3 （pD2 = 5.99） and M5 （pD2 = 6.70） subtypes. However, for （±）-DM-phencynonate hydrochloride, no significant subtype receptor selectivity was found. Both （±）-DM- and R-（-）-DM-phencynonate hydrochloride showed allosteric effects on muscarinic receptors, the Hill coefficient （nH） of five receptor subtypes was less than 1, respectively. The results revealed that R-（-）-DM-phencynonate hydrochloride showed selectivity torwards M4 subtype, and there were allosteric effects for both R-（-）-DM-phencynonate hydrochloride and （±）-DM-phencynonate hydrochloride on muscarinic receptors.展开更多
While common in biological systems,building blocks with low symmetry and flexibility pose numerous problems for synthetic self-assembly,such as the formation of isomers of assemblies that are difficult to distinguish ...While common in biological systems,building blocks with low symmetry and flexibility pose numerous problems for synthetic self-assembly,such as the formation of isomers of assemblies that are difficult to distinguish and purify.In this work,three aromatic amide-based ligands(L1–L3)with a central 1,8-diazatriptycene core were designed and used for selfassembly with Pd^(2+).While hundreds of stereoisomers based on the conformational flexibility around the amides and the unsymmetrical nonplanar structure of the core are possible upon coordination with the metal,the constraints designed into the ligands direct the self-assembly toward only a single Pd_(2)L_(4)cage(L1)or Pd_(4)L_(8)double-walled metallomacrocycle(L2)structure,even in mixtures of the ligands.This structural approach and the modularity of the ligand synthesis affords ready access to deep cavitands with endohedral functionalization(L3).These results highlight the potential of this new design strategy and open the door to selectively functionalized cavity-based architectures for numerous applications.展开更多
文摘Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,temperature-programmed reduction of H2,temperature-programmed desorption of NH3,infrared spectroscopy of adsorbed pyridine,H2 chemisorption,nitrogen adsorption-desorption,scanning electron microscopy and thermogravimetric analysis were performed.Kinetics of n-C7 isomerization were investigated under various hydrogen and n-C7 pressures,and the effects of reaction conditions on catalytic performance were studied.The results showed that bi-and trimetallic catalysts exhibit better performance than monometallic catalysts for this reaction.For example,a maximum i-C7 selectivity（ 〉74%） and multibranched isomer selectivity（40%） were observed for Pt-Sn/HZSM5-HMS at 200 ℃.
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China(Grant No.21978323)。
文摘To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.
基金the National Natural Science Foundation of China(21531003,21501024 and 21971035)Jilin Scientific and Technological Development Program(20170101198JC and 20190103017JH)+2 种基金Jilin Education Office(JJKH20180015KJ)“111”Program(B18012)open projects from the State Key Laboratory of Inorganic Synthesis&Preparative Chemistry and State Key Laboratory of Heavy Oil Processing(2018-8,SKLOP201902003)。
文摘Ultrathin zeolite membranes are of paramount importance in accelerating gas transport during membrane separation,and lowering down their membrane thicknesses to submicron scale is deemed to be very challenging.Herein,we develop an advanced approach of surface gel conversion for synthesis of submicron-thick pure silica MFI(silicalite-1)zeolite membranes.Viscous gel is prepared by finely adjusting the precursor composition,enabling its reduced wettability.The unfavorable wetting of the support surface can effectively prevent gel penetration into alumina support voids.Aided by the seeds,the surface gel is directly and fully crystallized into an MFI zeolite membrane with minimal water steam.A membrane with a thickness of 500 nm is successfully acquired and it is free of visible cracks.Additionally,the as-synthesized membranes exhibit rapid and selective separation of hexane isomers by virtue of unprecedentedly high n-hexane permeance of 24.5×10^−7 mol m^−2 s^−1 Pa^−1 and impressive separation factors of 13.3-22.6 for n-hexane over its isomers.This developed approach is of practical interest for sustainable synthesis of high-quality zeolite membranes.
文摘目的:探讨不同梯度浓度顺铂(CDDP)处理不同肺癌细胞后新发现的剪接因子SRSF7 m RNA异构体在同浓度CDDP处理后不同的细胞中的水平变化。方法:采用梯度浓度的CDDP处理肺癌细胞A549(8、18、24、32、40、48及56μmol/L)和H1299(12、24、36、48、60、72及84μmol/L),处理24 h后提取总RNA,进行RT-PCR检测SRSF7 m RNA剪接异构体,并选取NCBI中未确定的异构体进行TA克隆后测序并分析鉴定异构体类型;用56μmol/L的CDDP处理人胚肾细胞293FT,宫颈癌细胞Ca Ski、Si Ha、C33A细胞24 h,提取总RNA后验证新发现的SRSF7 m RNA剪切异构体是否存在这些细胞中。结果:发现3种新的SRSF7 m RNA剪接异构体(分别标记为New1、New2及New3),在肺癌细胞A549、H1299,人胚肾细胞293FT,宫颈癌细胞Ca Ski、Si Ha、C33A细胞等多种肿瘤细胞中均存在,根据NCBI的预测New1,New2,New3异构体均为非编码蛋白的m RNA异构体,随着处理CDDP浓度的增加,其比例明显上升;而编码蛋白的m RNA异构体a和(或)b所占比例明显下降;同时SRSF7的总m RNA水平逐渐降低。结论:新发现的3种非编码的m RNA异构体的变化揭示细胞可能通过SRSF7自身的m RNA选择性剪接来应对DNA损伤。
文摘1,3-偶极环加成反应有多种选择性,因此产物往往也是由多个异构体组成.天然产物青藤碱进行1,3-偶极环加成反应杂环化时,产物理论上有四个异构体,实验中只发现两个异构体.本文分析了青藤碱1,3-偶极环加成反应中的选择性,再根据产物的1 H NMR、13C NMR、NOESY相关谱、电子效应、空间效应的分析,结合理论计算和软件模拟,最终确定了所得两种产物异构体-1和异构体-2的构型.本文的推定方法,在判定具有类似电子效应和空间效应的1,3-偶极环加成反应产物结构时,能起到一定的借鉴作用.
文摘In this work, the structures of a pair of isomers were identified. And we showed the ability of the selective 1D version, performed the most common NMR experiments including the 1D-HMBC and GOESY experiments, to determine the isom^ric composition that were found in the production process of roflumilast. The experimental results proved that this method would be even more time saving and could get more reliable results.
基金National Natural Science Foundation of China (Grant No. 30672445)
文摘In order to compare the potential selectivity of R-（-）-DM-phencynonate hydrochloride with its racemate （±）-DM- phencynonate hydrochloride on acetylcholine muscarinic receptor subtypes, the five human acetylcholine muscarinic receptor subtypes （M1- M5） （CHO-hml-5R） were cloned and expressed in Chinese hamster ovary （CHO-K1） cell line. The specific mRNAs of the five acetylcholine muscarinic receptor subtypes were detected by the reverse transcription-polymerase chain reaction （RT-PCR） method, demonstrating the definite expression of muscarinic receptor subtype genes （CHO-hml-5R）. The affinity and saturability of different muscarinic receptor subtypes to [^3H] N-methylscopolamine （[^3H]-NMS） were obtained by radioligand binding assay. Equilibrium binding assay revealed that the maximum binding capacity of [^3H]-NMS （Bmax value） to CHO-hml-5R were 40.22±3.23, 24.53±4.11, 29.65±2.65, 25.41±2.46, 32.78±4.81 pmol/mg·protein, respectively. Kd values of [^3H]-NMS to muscarinic receptors M1 to M5 were 0.97±0.22, 1.16±0.14, 0.99±0.06, 0.56±0.08, 1.12±0.06 nM, respectively. R-（-）-DM- phencynonate hydrochloride was found to block the M4 receptor with a much higher potency （pD2 = 7.48） than those displayed on M1 （pD2 = 6.20）, M2 （pD2 = 5.99）, M3 （pD2 = 5.99） and M5 （pD2 = 6.70） subtypes. However, for （±）-DM-phencynonate hydrochloride, no significant subtype receptor selectivity was found. Both （±）-DM- and R-（-）-DM-phencynonate hydrochloride showed allosteric effects on muscarinic receptors, the Hill coefficient （nH） of five receptor subtypes was less than 1, respectively. The results revealed that R-（-）-DM-phencynonate hydrochloride showed selectivity torwards M4 subtype, and there were allosteric effects for both R-（-）-DM-phencynonate hydrochloride and （±）-DM-phencynonate hydrochloride on muscarinic receptors.
基金supported in part through the Concerted Research Action(ARC16/21-074)and the China Scholarship Council(pre-doctoral fellowships for C.-L.L.).
文摘While common in biological systems,building blocks with low symmetry and flexibility pose numerous problems for synthetic self-assembly,such as the formation of isomers of assemblies that are difficult to distinguish and purify.In this work,three aromatic amide-based ligands(L1–L3)with a central 1,8-diazatriptycene core were designed and used for selfassembly with Pd^(2+).While hundreds of stereoisomers based on the conformational flexibility around the amides and the unsymmetrical nonplanar structure of the core are possible upon coordination with the metal,the constraints designed into the ligands direct the self-assembly toward only a single Pd_(2)L_(4)cage(L1)or Pd_(4)L_(8)double-walled metallomacrocycle(L2)structure,even in mixtures of the ligands.This structural approach and the modularity of the ligand synthesis affords ready access to deep cavitands with endohedral functionalization(L3).These results highlight the potential of this new design strategy and open the door to selectively functionalized cavity-based architectures for numerous applications.
