Lanthanum-based oxides are promising candidates for low-temperature oxidative coupling of methane(OCM).To further lower the OCM reaction temperature,the Ce doped flower-like La_(2)O_(2)CO_(3)microsphere catalysts were...Lanthanum-based oxides are promising candidates for low-temperature oxidative coupling of methane(OCM).To further lower the OCM reaction temperature,the Ce doped flower-like La_(2)O_(2)CO_(3)microsphere catalysts were synthesized,achieving a significantly low reaction temperature (375℃) while maintaining high C_(2) hydrocarbon selectivity (43.0%).Doping Ce into the lattice of La_(2)O_(2)CO_(3)created more surface oxygen vacancies and bulk lattice defects,which was in favor of the transformation and migration of oxygen species at 350–400℃.The designed H_(2) temperature-programmed reduction (H_(2)-TPR) experiments provided strong evidence that the low reaction temperature of La_(x)Ce_(1-x)O_(1.5+δ)can be attributed to the transformation and migration of oxygen species,which dynamically generated surface oxygen vacancies for continuous oxygen activation to selectively convert methane.Moreover,designed temperatureprogrammed surface reaction (TPSR) clarified that two kinds of surface oxygen species in La_(x)Ce_(1-x)O_(1.5+δ)catalysts were concerned with catalytic performance,that is,the surface chemisorbed oxygen species for the activation of CH_(2)and the formation of CH_(2)·intermediates,surface La-Ce-O lattice oxygen species that caused the excessive oxidation of CH_(2)·intermediates.Finally,the factors affecting the transformation and migration of oxygen species were explored.展开更多
Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product...Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.展开更多
Pt-based catalysts are widely used in propane dehydrogenation reaction for the production of propylene.Suppressing irreversible deactivation caused by the sintering of Pt particles under harsh conditions and regenerat...Pt-based catalysts are widely used in propane dehydrogenation reaction for the production of propylene.Suppressing irreversible deactivation caused by the sintering of Pt particles under harsh conditions and regeneration process is a significant challenge in this catalyst.Herein,a series of highly ordered mesoporous Al_(2)O_(3) supports with different levels of Al3+penta sites,are fabricated and used as the support to disperse Pt-Sn_(2) clusters.Characterizations of Pt-Sn_(2)/meso-Al_(2)O_(3) with XRD,NMR,CO-IR,STEM,TG,and Raman techniques along with propane dehydrogenation-regeneration cycles test reveal the structure-stability-re generability relationship.The coordinatively unsaturated pentacoordinate Al_(Al3+penta)^(3+)can strongly anchor Pt atoms via a formation of Al-O-Pt bond,and thus stabilize the Pt-based particles at the surface of Al_(2)O_(3).The stability and regenerability of Pt-Sn2/meso-Al_(2)O_(3) are strongly dependent on the content of Al3+penta sites in the Al_(2)O_(3) structure,and a high level of Al3+penta sites can effectively prevent the agglomeration of Pt-Sn2 clusters into large Pt nanoparticles in the consecutive dehydrogenation-regeneration cycles.The Pt-Sn2/meso-Al_(2)O_(3)-600 with the highest level of Al_(penta)^(3+) (50.8%)delivers the best performance in propane dehydrogenation,which exhibits propane conversion of 40%and propylene selectivity above 98%at 570℃ with 10 vol%C_(3)H_(8) and 10 vol% H_(2) feed.A slow deactivation in this catalyst is ascribed to the formation of coke,and the catalytic performance can be fully restored in the consecutive dehydrogenation-regeneration cycles via a simple calcination treatment.展开更多
A series of PtSn/hierarchical ZSM-5 catalysts were developed for propane dehydrogenation,in which the PtSn bimetallic particles are confined in the mesopores of hierarchical ZSM-5 zeolite.The synthesis of PtSn/hierarc...A series of PtSn/hierarchical ZSM-5 catalysts were developed for propane dehydrogenation,in which the PtSn bimetallic particles are confined in the mesopores of hierarchical ZSM-5 zeolite.The synthesis of PtSn/hierarchical ZSM-5 catalysts was achieved via the loading of Pt and Sn species onto the hierarchical ZSM-5 catalysts that are obtained through a desilication of conventional ZSM-5.The PtSn/hierarchical ZSM-5 catalysts were fully characterized by XRD,N_(2) adsorption,STEM,XPS,and CO-IR techniques,which reveals that highly dispersed PtSn bimetallic nanoparticles are enclosed into mesopores of hierarchical ZSM-5.The catalytic performance of PtSn/hierarchical ZSM-5 is greatly affected by the concentrations of alkali solution in the desilication process and Sn/Pt ratios in PtSn bimetallic particles.The PtSn1.00/ZSM-5(0.8)catalyst shows the highest efficiency in propane dehydrogenation,which gives an initial conversion of 46%and selectivity of 98%at 570℃.The high efficiency in these PtSn/hierarchical ZSM-5 catalysts for propane dehydrogenation is mainly ascribed to the confinement of PtSn particles in the mesopores of hierarchical ZSM-5 zeolite.展开更多
The prognosis of patients with previously treated tuberculosis (TB) was suggested to be dependent on whether the initial treatment was in compliance with the established guidelines. The aim of this retrospective multi...The prognosis of patients with previously treated tuberculosis (TB) was suggested to be dependent on whether the initial treatment was in compliance with the established guidelines. The aim of this retrospective multicenter study was to determine the proportion of new TB patients who received standard doses of rifampicin in multiple provinces of China, and the relationship between low doses of rifampicin and frequency of rifampicin-resistance as well as treatment outcomes. A total of 713 new TB patients were treated with either once-daily dose of bulk anti-TB drugs (group I) or every other day combination blister packs of anti-TB drugs containing rifampicin (group II) at more than 30 TB treatment centers/hospitals in China. Treatment history, therapeutic doses of rifampicin, and information about patients were extracted from their medical records and analyzed, and rifampicin-resistance of isolates collected from patients following the treatment as well as treatment outcomes were compared between two treatment groups. Among 522 patients in treatment group I, 154 (29.5%) received standard and 363 (69.5%) received low doses of rifampicin;238 (45.6%) isolates were rifampicin-resistant, and 243 (46.6%) were successfully treated. Among 191 patients in treatment group II, 175 (91.6%) received standard and 15 (7.9%) received low doses of rifampicin;72 (37.7%) isolates were rifampicin-resistant, and 105 (55%) were successfully treated. When patients who received low doses of rifampicin were compared to others within the same treatment group, increased rates for rifampicin-resistance and treatment failure were observed. Results from this study showed that most new TB patients in treatment group I (69.5%) received low doses of rifampicin, and their treatment outcomes were worse than those in treatment group II, indicating that low doses of rifampicin used for the initial treatment of new TB patients were correlated to increased frequency of rifampicin-resistance and poorer treatment outcomes.展开更多
Highly dispersed Cu-base catalyst has been prepared via thermal decomposition of layered double hydroxides precursors. The XRD pattern and the HRTEM images of the as prepared catalyst confirmed the high dispersion of ...Highly dispersed Cu-base catalyst has been prepared via thermal decomposition of layered double hydroxides precursors. The XRD pattern and the HRTEM images of the as prepared catalyst confirmed the high dispersion of Cu and Fe ions. Results show that the catalyst has a relatively high selectivity of alkanes at low temperature.展开更多
Aberrant expression of microRNAs(miRNAs)was reported frequently in different human cancers.The major role of miRNA is targeting 30-UTR of coding gene and causing translational repression or mRNA degradation.miR-10b ov...Aberrant expression of microRNAs(miRNAs)was reported frequently in different human cancers.The major role of miRNA is targeting 30-UTR of coding gene and causing translational repression or mRNA degradation.miR-10b overexpression was reported to promote breast cancer metastasis by up-regulating RHOC expression.But its expression in hepatocellular carcinoma(HCC)remains unclear.Our study indicated that the expression of miR-10b was different in HCC and adjacent tissue samples,and reduced expression of miR-10b in HCC was related tovein invasion.High-level expression of RHOC was also related to vein invasion in HCC.But no correlation was found between miR-10b and RHOC expression.These results suggest that miR-10b and RHOC are independent predictors of HCC invasion and metastasis.展开更多
Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged l...Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings.Herein,we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates.This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone.Finally,it facilitates the synthesis of the entire skeletal structure of the pseudolaric acidfamily of natural products,excludingthe B-ringfunctionalization.展开更多
基金the Shanxi Science and Technology Department bidding project(No.20191101012)the autonomous research project of SKLCC(No.2020BWZ003)for providing financial support。
文摘Lanthanum-based oxides are promising candidates for low-temperature oxidative coupling of methane(OCM).To further lower the OCM reaction temperature,the Ce doped flower-like La_(2)O_(2)CO_(3)microsphere catalysts were synthesized,achieving a significantly low reaction temperature (375℃) while maintaining high C_(2) hydrocarbon selectivity (43.0%).Doping Ce into the lattice of La_(2)O_(2)CO_(3)created more surface oxygen vacancies and bulk lattice defects,which was in favor of the transformation and migration of oxygen species at 350–400℃.The designed H_(2) temperature-programmed reduction (H_(2)-TPR) experiments provided strong evidence that the low reaction temperature of La_(x)Ce_(1-x)O_(1.5+δ)can be attributed to the transformation and migration of oxygen species,which dynamically generated surface oxygen vacancies for continuous oxygen activation to selectively convert methane.Moreover,designed temperatureprogrammed surface reaction (TPSR) clarified that two kinds of surface oxygen species in La_(x)Ce_(1-x)O_(1.5+δ)catalysts were concerned with catalytic performance,that is,the surface chemisorbed oxygen species for the activation of CH_(2)and the formation of CH_(2)·intermediates,surface La-Ce-O lattice oxygen species that caused the excessive oxidation of CH_(2)·intermediates.Finally,the factors affecting the transformation and migration of oxygen species were explored.
基金the State Key Fundamental Research Program(Ministry of Science and Technology of China,No.2011CBA00501)Shanghai Municipal Science and Technology Commission,China(Grant No:11DZ1200300)the Foundation of State Key Laboratory of Coal Conversion(Grant No:1112610)
文摘Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.
基金Financial supports of the National Natural Science Foundation of China(21878050,91934301)the State Key Laboratory of Coal Conversion(J21-22-620)the 111 Project(D17005)。
文摘Pt-based catalysts are widely used in propane dehydrogenation reaction for the production of propylene.Suppressing irreversible deactivation caused by the sintering of Pt particles under harsh conditions and regeneration process is a significant challenge in this catalyst.Herein,a series of highly ordered mesoporous Al_(2)O_(3) supports with different levels of Al3+penta sites,are fabricated and used as the support to disperse Pt-Sn_(2) clusters.Characterizations of Pt-Sn_(2)/meso-Al_(2)O_(3) with XRD,NMR,CO-IR,STEM,TG,and Raman techniques along with propane dehydrogenation-regeneration cycles test reveal the structure-stability-re generability relationship.The coordinatively unsaturated pentacoordinate Al_(Al3+penta)^(3+)can strongly anchor Pt atoms via a formation of Al-O-Pt bond,and thus stabilize the Pt-based particles at the surface of Al_(2)O_(3).The stability and regenerability of Pt-Sn2/meso-Al_(2)O_(3) are strongly dependent on the content of Al3+penta sites in the Al_(2)O_(3) structure,and a high level of Al3+penta sites can effectively prevent the agglomeration of Pt-Sn2 clusters into large Pt nanoparticles in the consecutive dehydrogenation-regeneration cycles.The Pt-Sn2/meso-Al_(2)O_(3)-600 with the highest level of Al_(penta)^(3+) (50.8%)delivers the best performance in propane dehydrogenation,which exhibits propane conversion of 40%and propylene selectivity above 98%at 570℃ with 10 vol%C_(3)H_(8) and 10 vol% H_(2) feed.A slow deactivation in this catalyst is ascribed to the formation of coke,and the catalytic performance can be fully restored in the consecutive dehydrogenation-regeneration cycles via a simple calcination treatment.
基金supports of the National Natural Science Foundation of China(21878050,22178062)Foundation of State Key Labora-tory of Coal Conversion(J21-22-620)Green Petrochemical Engineering Base of Intelligence Introduction for Innovation(111 Project D17005)are gratefully acknowledged.
文摘A series of PtSn/hierarchical ZSM-5 catalysts were developed for propane dehydrogenation,in which the PtSn bimetallic particles are confined in the mesopores of hierarchical ZSM-5 zeolite.The synthesis of PtSn/hierarchical ZSM-5 catalysts was achieved via the loading of Pt and Sn species onto the hierarchical ZSM-5 catalysts that are obtained through a desilication of conventional ZSM-5.The PtSn/hierarchical ZSM-5 catalysts were fully characterized by XRD,N_(2) adsorption,STEM,XPS,and CO-IR techniques,which reveals that highly dispersed PtSn bimetallic nanoparticles are enclosed into mesopores of hierarchical ZSM-5.The catalytic performance of PtSn/hierarchical ZSM-5 is greatly affected by the concentrations of alkali solution in the desilication process and Sn/Pt ratios in PtSn bimetallic particles.The PtSn1.00/ZSM-5(0.8)catalyst shows the highest efficiency in propane dehydrogenation,which gives an initial conversion of 46%and selectivity of 98%at 570℃.The high efficiency in these PtSn/hierarchical ZSM-5 catalysts for propane dehydrogenation is mainly ascribed to the confinement of PtSn particles in the mesopores of hierarchical ZSM-5 zeolite.
文摘The prognosis of patients with previously treated tuberculosis (TB) was suggested to be dependent on whether the initial treatment was in compliance with the established guidelines. The aim of this retrospective multicenter study was to determine the proportion of new TB patients who received standard doses of rifampicin in multiple provinces of China, and the relationship between low doses of rifampicin and frequency of rifampicin-resistance as well as treatment outcomes. A total of 713 new TB patients were treated with either once-daily dose of bulk anti-TB drugs (group I) or every other day combination blister packs of anti-TB drugs containing rifampicin (group II) at more than 30 TB treatment centers/hospitals in China. Treatment history, therapeutic doses of rifampicin, and information about patients were extracted from their medical records and analyzed, and rifampicin-resistance of isolates collected from patients following the treatment as well as treatment outcomes were compared between two treatment groups. Among 522 patients in treatment group I, 154 (29.5%) received standard and 363 (69.5%) received low doses of rifampicin;238 (45.6%) isolates were rifampicin-resistant, and 243 (46.6%) were successfully treated. Among 191 patients in treatment group II, 175 (91.6%) received standard and 15 (7.9%) received low doses of rifampicin;72 (37.7%) isolates were rifampicin-resistant, and 105 (55%) were successfully treated. When patients who received low doses of rifampicin were compared to others within the same treatment group, increased rates for rifampicin-resistance and treatment failure were observed. Results from this study showed that most new TB patients in treatment group I (69.5%) received low doses of rifampicin, and their treatment outcomes were worse than those in treatment group II, indicating that low doses of rifampicin used for the initial treatment of new TB patients were correlated to increased frequency of rifampicin-resistance and poorer treatment outcomes.
文摘Highly dispersed Cu-base catalyst has been prepared via thermal decomposition of layered double hydroxides precursors. The XRD pattern and the HRTEM images of the as prepared catalyst confirmed the high dispersion of Cu and Fe ions. Results show that the catalyst has a relatively high selectivity of alkanes at low temperature.
基金supported by the National Basic Research Program of China (2012CB934002, 2010CB912802)National High-tech R&D Program of China (2012AA02A203, 2012AA02A209, 2012AA02A504)+2 种基金National Key Scientific instrument Special Program of China (2011YQ03013405)the National Natural Science Foundation of China (81121004, 81071953, 81161120432)National Key Scientific Research Program of China (Grant No. 2010CB912801)
文摘Aberrant expression of microRNAs(miRNAs)was reported frequently in different human cancers.The major role of miRNA is targeting 30-UTR of coding gene and causing translational repression or mRNA degradation.miR-10b overexpression was reported to promote breast cancer metastasis by up-regulating RHOC expression.But its expression in hepatocellular carcinoma(HCC)remains unclear.Our study indicated that the expression of miR-10b was different in HCC and adjacent tissue samples,and reduced expression of miR-10b in HCC was related tovein invasion.High-level expression of RHOC was also related to vein invasion in HCC.But no correlation was found between miR-10b and RHOC expression.These results suggest that miR-10b and RHOC are independent predictors of HCC invasion and metastasis.
基金the National Natural Science Foundation of China(Nos.22071205,22301251 and 21772164)China Postdoctoral Science Foundation(2023M732942),NFFTBS(J1310024)+1 种基金NCETFJ,and PCSIRT is acknowledgedthe financial support(No.202005)from State Key Laboratory of Elemento-Organic Chemistry,Nankai University.
文摘Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities.The main structural feature of their framework is a trans-fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings.Herein,we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates.This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone.Finally,it facilitates the synthesis of the entire skeletal structure of the pseudolaric acidfamily of natural products,excludingthe B-ringfunctionalization.
