The HGF/c-Met pathway plays an important role in the proliferation, invasion, angiogenesis, and metastasis of tumors. With the successful development of small molecule c-Met kinase inhibitors, this signal pathway has ...The HGF/c-Met pathway plays an important role in the proliferation, invasion, angiogenesis, and metastasis of tumors. With the successful development of small molecule c-Met kinase inhibitors, this signal pathway has become the focus of oncology research. In this review, we discuss the basic mechanism, targeted therapy, and early results of clinical trials of the HGF/c-Met pathway.展开更多
Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis...Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.展开更多
Spectroscopic study of water splitting by neutral metal clusters is crucial to understanding the microscopic mechanism of catalytic processes but has been proven to be a challenging experimental target due to the diff...Spectroscopic study of water splitting by neutral metal clusters is crucial to understanding the microscopic mechanism of catalytic processes but has been proven to be a challenging experimental target due to the difficulty in size selection.Here,we report a size-specific infrared spectroscopic study of the reactions between neutral group 3 metals and water molecules based on threshold photoionization using a vacuum ultraviolet laser.Quantum chemical calculations were carried out to identify the structures and to assign the experimental spectra.All the M_(2)O_(4)H_(4)(M=Sc,Y,La)products are found to have the intriguing M_(2)(μ_(2)-O)(μ_(2)-H)(μ_(2)-OH)(η^(1)-OH)_(2) structures,indicating that the H-OH bond breaking,the M-O/M-H/M-OH bond formation,and hydrogen production proceed efficiently in the reactions between laser-vaporized metals and water molecules.The joint experimental and theoretical results on the atomic scale demonstrate that the water splitting by neutral group 3 metals is both thermodynamically exothermic and kinetically facile in the gas phase.These findings have important implications for unravelling the structure-reactivity relationship of catalysts with isolated metal atoms/clusters dispersed on supports.展开更多
The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy....The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy.During the consecutive CO adsorption,the μ^(2)-O-bent structure initially is the most favorable for TaNiO(CO)_(5),and subsequently both μ^(2)-O-bent and μ^(2)-O-linear structures are degenerate for TaNiO(CO)_(6),then the μ^(2)-O-linear structure is most preferential for TaNiO(CO)_(7),and finally the η^(2)-CO_(2)-tagged structure is the most ene rgetically competitive one for TaNiO(CO)_(8),i.e., the CO oxidation occurs at n=8.ln contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir-Hinshelwood-like mechanism,complementary theo retical calculations suggest that both Langmuir-Hinshelwood-like and Eley-Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)_(8) complex.Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes,of which the composition be tailored to fulfill the desired chemical behaviors.展开更多
Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes suc...Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes such as Fischer-Tropsch chemistry and alcohol synthesis.Here,we use mass-selected photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to study the reactions of CO molecules with several heterobinuclear transition metal-iron clusters M-Fe(M=Ti,V,Cr).The mass spectra reveal the favorable formation of MFe(CO)_(4)^(-)with relatively high thermodynamic stability.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) complexes are established to have a metal-Fe bonded M-Fe(CO)_(4) structure with C_(3 v) geometry.While the positive charge and unpaired electrons are mainly located on the M atom,the natural charge of Fe(CO)_(4) is about-2 e.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) can be seen as being formed via the interactions between the M^(+)fragment and the [Fe(CO)_(4)]^(2-)core,which satisfies the 18-electron rule.The CO molecules are remarkably activated in these MFe(CO)_(4)^(-).These results shed insight into the structure-reactivity relationship of heterobinuclear transition metal carbonyls and would have important implications for understanding of CO activation on alloy surfaces.展开更多
The intramolecular O−H…πhydrogen bond has garnered significant research interest in recent decades.In this work,we utilized the infrared(IR)-vacuum-ultraviolet(VUV)nonresonant ionization detected IR spectroscopy(NRI...The intramolecular O−H…πhydrogen bond has garnered significant research interest in recent decades.In this work,we utilized the infrared(IR)-vacuum-ultraviolet(VUV)nonresonant ionization detected IR spectroscopy(NRID-IR)method to study the molecular structure of neutral and cationic 2-methylallyl alcohol(MAA,CH_(2)=C(CH_(3))−CH_(2)−OH).Density functional theory calculations revealed five stable neutral and three stable cationic MAA conformers,respectively.Two neutral MAA conformers are expected to have an O−H…πintramolecular hydrogen bond interaction,based on the structural characterization that the OH group is directed toward the C=C double bond.The IR spectra of both neutral(2700−3700 cm^(−1))and cationic MAA(2500−7200 cm^(−1))were measured,and the anharmonic IR spectra were calculated at the B3LYP-D3(BJ)/def2-TZVPP level.The OH stretching vibration frequency of neutral MAA was observed at 3656 cm−1,slightly lower than those of methanol and ethanol.In contrast,the OH stretching vibration of cationic MAA was red-shifted by about 140 cm^(−1)compared to neutral MAA.The interaction region indicator and natural bond orbital analysis suggest that the O−H…πinteraction in neutral MAA is weak,and may not play a major role in stabilizing the neutral MAA.展开更多
Liquified natural gas(LNG)bunkering simultaneous operations(SIMOPs)refers to the operations(such as cargo operations,port activities and ship maintenance)occurring around LNG bunkering.SIMOPs pose new risks to LNG bun...Liquified natural gas(LNG)bunkering simultaneous operations(SIMOPs)refers to the operations(such as cargo operations,port activities and ship maintenance)occurring around LNG bunkering.SIMOPs pose new risks to LNG bunkering,because the operations are dynamically interlocked in which the occurrence probabilities of potential consequences change at different times due to commencement or completion of specific SIMOP events.However,traditional static risk assessment approaches are not able to take the dynamic nature of these new risks into account.This article proposes a dynamic quantitative risk as-sessment(DQRA)methodology based on the Bayesian network(BN)to develop better understanding of dynamic risks of LNG bunkering SIMOPs.The methodology is demonstrated and evaluated through a truck-to-ship LNG bunkering case study.The results and discussion of the case study validate the utility of the proposed methodology and demonstrate that BNs are efficient in performing the probability calcu-lations and are flexible in conducting causal diagnosis.The main innovation of this work is realizing the quantification of risks at different times,which reflects the most essential time-changing characteristics of risks associated with LNG bunkering SIMOPs.展开更多
The adsorption and dissociation of CH3OH on TiO2 （110） were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML （1 ML=5.2× 10^14 molecules/cm2） co...The adsorption and dissociation of CH3OH on TiO2 （110） were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML （1 ML=5.2× 10^14 molecules/cm2） coverage at five-coordinated titanium （Tisc） sites to form the first layer. In the second layer, the CH3OH is adsorbed at bridge-bonded oxygen, and from the third layer, the CH3OH molecules form a hydrogen-bonded network with each other. The theoretical results show that dissociation of multilayer adsorbed methanol to aldehyde occurs through a stepwise pathway, with easy O-H bond dissociation and rate-determining C-H bond dissociation. The dissociation barriers for 8 or 12 CH3OH molecules on TiO2 are higher than that for low coverage by 0.15-0.21 eV; this suggests that the dissociation of multilayer adsorbed CH3OH is harder.展开更多
Importance:There is a high incidence of iron deficiency in children worldwide.Notably,however,while iron deficiency is the most common cause of anemia,little is known about the prevalence and different types of iron d...Importance:There is a high incidence of iron deficiency in children worldwide.Notably,however,while iron deficiency is the most common cause of anemia,little is known about the prevalence and different types of iron deficiency in neuroblastoma patients.Objective:The aim of the present study was to investigate the prevalence of iron deficiency in patients newly diagnosed with neuroblastoma.Methods:A total of 195 newly diagnosed neuroblastoma patients from November 2015 to January 2018 were analyzed retrospectively.The survival analysis was estimated by the Kaplan-Meier method.Results:Of the 195 neuroblastoma patients included in the study,121(62.1%)had iron deficiency,55(28.2%)had absolute iron deficiency,and 66(33.9%)had functional iron deficiency.Being aged≥18 months,tumor originating in the abdomen,International Neuroblastoma Risk Group Staging System M,high-risk neuroblastoma,lactate dehydrogenase≥1500 U/L,neuron-specific enolase≥100 U/L,unfavorable histologic category,MYCN amplification,chromosome 1p loss,and bone marrow metastasis were associated with significantly higher rates of functional iron deficiency(P<0.05).Interpretation:Functional iron deficiency at the time of initial neuroblastoma diagnosis predicted lower event-free survival.Long-term effects of iron supplementation in neuroblastoma patients with different types of iron deficiency need to be further studied.展开更多
文摘The HGF/c-Met pathway plays an important role in the proliferation, invasion, angiogenesis, and metastasis of tumors. With the successful development of small molecule c-Met kinase inhibitors, this signal pathway has become the focus of oncology research. In this review, we discuss the basic mechanism, targeted therapy, and early results of clinical trials of the HGF/c-Met pathway.
文摘Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.
基金the Dalian Coherent Light Source (DCLS) for support and assistancesupported by the National Key Research and Development Program of China (No.2021YFA1400501)+6 种基金the National Natural Science Foundation of China (Nos.22125303,92061203,92061114,21976049,22103082,22273101 and 22288201)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (CAS)(No.2020187)Innovation Program for Quantum Science and Technology (No.2021ZD0303304)CAS (No.GJJSTD20220001)Dalian Institute of Chemical Physics (No.DICP DCLS201702)International Partnership Program of CAS (No.121421KYSB20170012)K.C.Wong Education Foundation (No.GJTD-2018-06).
文摘Spectroscopic study of water splitting by neutral metal clusters is crucial to understanding the microscopic mechanism of catalytic processes but has been proven to be a challenging experimental target due to the difficulty in size selection.Here,we report a size-specific infrared spectroscopic study of the reactions between neutral group 3 metals and water molecules based on threshold photoionization using a vacuum ultraviolet laser.Quantum chemical calculations were carried out to identify the structures and to assign the experimental spectra.All the M_(2)O_(4)H_(4)(M=Sc,Y,La)products are found to have the intriguing M_(2)(μ_(2)-O)(μ_(2)-H)(μ_(2)-OH)(η^(1)-OH)_(2) structures,indicating that the H-OH bond breaking,the M-O/M-H/M-OH bond formation,and hydrogen production proceed efficiently in the reactions between laser-vaporized metals and water molecules.The joint experimental and theoretical results on the atomic scale demonstrate that the water splitting by neutral group 3 metals is both thermodynamically exothermic and kinetically facile in the gas phase.These findings have important implications for unravelling the structure-reactivity relationship of catalysts with isolated metal atoms/clusters dispersed on supports.
基金supported by the National Natural Science Foundation of China (Nos.21603130,21673231,21688102 and 21873097)the Key Research Program (No.KGZD-EW-T05)+2 种基金the Strategic Priority Research Program (No.XDB17000000) of the Chinese Academy of Sciencethe Shanxi Province Science Foundation for Youths (No. 201901D211395)the 1331 Engineering of Shanxi Province and the Start-up Fund from Shanxi Normal University for support。
文摘The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy.During the consecutive CO adsorption,the μ^(2)-O-bent structure initially is the most favorable for TaNiO(CO)_(5),and subsequently both μ^(2)-O-bent and μ^(2)-O-linear structures are degenerate for TaNiO(CO)_(6),then the μ^(2)-O-linear structure is most preferential for TaNiO(CO)_(7),and finally the η^(2)-CO_(2)-tagged structure is the most ene rgetically competitive one for TaNiO(CO)_(8),i.e., the CO oxidation occurs at n=8.ln contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir-Hinshelwood-like mechanism,complementary theo retical calculations suggest that both Langmuir-Hinshelwood-like and Eley-Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)_(8) complex.Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes,of which the composition be tailored to fulfill the desired chemical behaviors.
基金supported by the National Natural Science Foundation of China (21688102, 21873097, and 92061203)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (CAS)(2020187)+3 种基金the Strategic Priority Research Program of CAS (XDB17000000)CAS (GJJSTD20190002)the International Partnership Program of CAS (121421KYSB20170012)the K.C.Wong Education Foundation (GJTD-2018-06)。
文摘Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes such as Fischer-Tropsch chemistry and alcohol synthesis.Here,we use mass-selected photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to study the reactions of CO molecules with several heterobinuclear transition metal-iron clusters M-Fe(M=Ti,V,Cr).The mass spectra reveal the favorable formation of MFe(CO)_(4)^(-)with relatively high thermodynamic stability.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) complexes are established to have a metal-Fe bonded M-Fe(CO)_(4) structure with C_(3 v) geometry.While the positive charge and unpaired electrons are mainly located on the M atom,the natural charge of Fe(CO)_(4) is about-2 e.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) can be seen as being formed via the interactions between the M^(+)fragment and the [Fe(CO)_(4)]^(2-)core,which satisfies the 18-electron rule.The CO molecules are remarkably activated in these MFe(CO)_(4)^(-).These results shed insight into the structure-reactivity relationship of heterobinuclear transition metal carbonyls and would have important implications for understanding of CO activation on alloy surfaces.
基金gratefully acknowledge the Dalian Coherent Light Source(DCLS)for support and assistanceThis work was supported by the National Natural Science Foundation of China(No.22288201)+1 种基金the Chinese Academy of Sciences(GJJSTD20220001)the Innovation Program for Quantum Science and Technology(No.2021ZD0303305).
文摘The intramolecular O−H…πhydrogen bond has garnered significant research interest in recent decades.In this work,we utilized the infrared(IR)-vacuum-ultraviolet(VUV)nonresonant ionization detected IR spectroscopy(NRID-IR)method to study the molecular structure of neutral and cationic 2-methylallyl alcohol(MAA,CH_(2)=C(CH_(3))−CH_(2)−OH).Density functional theory calculations revealed five stable neutral and three stable cationic MAA conformers,respectively.Two neutral MAA conformers are expected to have an O−H…πintramolecular hydrogen bond interaction,based on the structural characterization that the OH group is directed toward the C=C double bond.The IR spectra of both neutral(2700−3700 cm^(−1))and cationic MAA(2500−7200 cm^(−1))were measured,and the anharmonic IR spectra were calculated at the B3LYP-D3(BJ)/def2-TZVPP level.The OH stretching vibration frequency of neutral MAA was observed at 3656 cm−1,slightly lower than those of methanol and ethanol.In contrast,the OH stretching vibration of cationic MAA was red-shifted by about 140 cm^(−1)compared to neutral MAA.The interaction region indicator and natural bond orbital analysis suggest that the O−H…πinteraction in neutral MAA is weak,and may not play a major role in stabilizing the neutral MAA.
文摘Liquified natural gas(LNG)bunkering simultaneous operations(SIMOPs)refers to the operations(such as cargo operations,port activities and ship maintenance)occurring around LNG bunkering.SIMOPs pose new risks to LNG bunkering,because the operations are dynamically interlocked in which the occurrence probabilities of potential consequences change at different times due to commencement or completion of specific SIMOP events.However,traditional static risk assessment approaches are not able to take the dynamic nature of these new risks into account.This article proposes a dynamic quantitative risk as-sessment(DQRA)methodology based on the Bayesian network(BN)to develop better understanding of dynamic risks of LNG bunkering SIMOPs.The methodology is demonstrated and evaluated through a truck-to-ship LNG bunkering case study.The results and discussion of the case study validate the utility of the proposed methodology and demonstrate that BNs are efficient in performing the probability calcu-lations and are flexible in conducting causal diagnosis.The main innovation of this work is realizing the quantification of risks at different times,which reflects the most essential time-changing characteristics of risks associated with LNG bunkering SIMOPs.
基金financially supported by National Natural Science Foundation of China(21173212)the Key Research Program of the Chinese Academy of Sciences
文摘The adsorption and dissociation of CH3OH on TiO2 （110） were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML （1 ML=5.2× 10^14 molecules/cm2） coverage at five-coordinated titanium （Tisc） sites to form the first layer. In the second layer, the CH3OH is adsorbed at bridge-bonded oxygen, and from the third layer, the CH3OH molecules form a hydrogen-bonded network with each other. The theoretical results show that dissociation of multilayer adsorbed methanol to aldehyde occurs through a stepwise pathway, with easy O-H bond dissociation and rate-determining C-H bond dissociation. The dissociation barriers for 8 or 12 CH3OH molecules on TiO2 are higher than that for low coverage by 0.15-0.21 eV; this suggests that the dissociation of multilayer adsorbed CH3OH is harder.
基金The study was funded by Beijing Municipal Science and Technology Commission(Grant No.Z151100004015159).
文摘Importance:There is a high incidence of iron deficiency in children worldwide.Notably,however,while iron deficiency is the most common cause of anemia,little is known about the prevalence and different types of iron deficiency in neuroblastoma patients.Objective:The aim of the present study was to investigate the prevalence of iron deficiency in patients newly diagnosed with neuroblastoma.Methods:A total of 195 newly diagnosed neuroblastoma patients from November 2015 to January 2018 were analyzed retrospectively.The survival analysis was estimated by the Kaplan-Meier method.Results:Of the 195 neuroblastoma patients included in the study,121(62.1%)had iron deficiency,55(28.2%)had absolute iron deficiency,and 66(33.9%)had functional iron deficiency.Being aged≥18 months,tumor originating in the abdomen,International Neuroblastoma Risk Group Staging System M,high-risk neuroblastoma,lactate dehydrogenase≥1500 U/L,neuron-specific enolase≥100 U/L,unfavorable histologic category,MYCN amplification,chromosome 1p loss,and bone marrow metastasis were associated with significantly higher rates of functional iron deficiency(P<0.05).Interpretation:Functional iron deficiency at the time of initial neuroblastoma diagnosis predicted lower event-free survival.Long-term effects of iron supplementation in neuroblastoma patients with different types of iron deficiency need to be further studied.
