Acute cerebral ischemia caused by stroke,traumatic brain injury(TBI),or systemic acute conditions such as hemorrhagic shock,cardiac arrest,or disseminated intravascular coagulation results in an energy crisis in local...Acute cerebral ischemia caused by stroke,traumatic brain injury(TBI),or systemic acute conditions such as hemorrhagic shock,cardiac arrest,or disseminated intravascular coagulation results in an energy crisis in local sites or the whole brain.The disruption of cerebral blood flow deprives the brain cells of oxygen and glucose,the essential substrates for adenosine triphosphate(ATP)synthesis.As a result,oxidative phosphorylation in the mitochondria fails,forcing cells to rely on anaerobic glycolysis(He et al.,2020).Although this compensatory mechanism maintains short-term energy production under hypoxic conditions,overall ATP production is significantly reduced.Neurons,which are highly susceptible to ischemic injury,deplete their ATP stores faster than glial cells(e.g.,astrocytes),which have some energy reserves.展开更多
Static one-handed helical polymers can serve as an ideal catalytic platform toward chiral synthesis.As a demonstration of helical polyisocyanides in asymmetric catalysis,we report a novel strategy to facilitate asymme...Static one-handed helical polymers can serve as an ideal catalytic platform toward chiral synthesis.As a demonstration of helical polyisocyanides in asymmetric catalysis,we report a novel strategy to facilitate asymmetric cooperative catalysis for the kinetic resolution of epoxides with TMSN_(3) using one-handed polyisocyanide-supported Co(III)-salen catalysts.Co(III)-salen is decorated with polyisocyanides to produce the polymer-supported catalyst P1-Co-N_(3).Owing to the rigid helical backbone of the polyisocyanide skeleton,spatially adjacent Co(III)-salen pendants are arranged with a distance of~1.2 nm so that the epoxide and TMSN_(3) can undergo dual activation in an amplified chiral environment.The catalytic performance is investigated via the kinetic resolution for a series of terminal epoxides through enantioselective ring-opening with TMSN_(3).P1-Co-N_(3) exhibits high catalytic activity and enantioselectivity,producing the desired products in high enantiomeric excesses and good yields at a low catalyst loading(0.6 mol%).In contrast,a small molecular control,S1-Co-N_(3),performs poorly owing to the absence of a preorganized catalytic dimer.Moreover,this polyisocyanide-based catalyst exhibits good functional group tolerance and stable activity in multiple recycles.To demonstrate its potential application in the asymmetric synthesis of chiral drugs,we conducted a gram-scale asymmetric synthesis ofβ-amino acid derivatives via this kinetic resolution method as the essential step.展开更多
Photocatalytic splitting of water to produce hydrogen is a potential solution to alleviate environmental pollution and the energy crisis.It is shown here that H_(3)PMo_(12)O_(4)0(PMo_(12))as a co-catalyst with CdS nan...Photocatalytic splitting of water to produce hydrogen is a potential solution to alleviate environmental pollution and the energy crisis.It is shown here that H_(3)PMo_(12)O_(4)0(PMo_(12))as a co-catalyst with CdS nanosheets can form a well-designed composite photocatalyst without the aid of precious metals by microwave synthesis.A small loading of PMo_(12)(1.8%Mo)exhibits highly efficient photocatalytic perform-ance with a maximum hydrogen production of 5.7 mmol h^(−1)g^(−1),nearly six times higher than that of iso-lated CdS nanosheets.The charge transfer process in the photocatalytic system was further confirmed by XPS analysis,where PMo_(12)accelerated the separation of photogenerated carriers,shortened the charge transfer distance and substantially enhanced the photogeneration efficiency and stability of water clea-vage to hydrogen.This combination of polyoxometalates and CdS has promising applications and pro-vides a new way to develop efficient and novel photocatalysts for sustainable solar energy utilization strategies.展开更多
基金supported by the Russian Science Foundation,grant 24-75-10013(to NVA).
文摘Acute cerebral ischemia caused by stroke,traumatic brain injury(TBI),or systemic acute conditions such as hemorrhagic shock,cardiac arrest,or disseminated intravascular coagulation results in an energy crisis in local sites or the whole brain.The disruption of cerebral blood flow deprives the brain cells of oxygen and glucose,the essential substrates for adenosine triphosphate(ATP)synthesis.As a result,oxidative phosphorylation in the mitochondria fails,forcing cells to rely on anaerobic glycolysis(He et al.,2020).Although this compensatory mechanism maintains short-term energy production under hypoxic conditions,overall ATP production is significantly reduced.Neurons,which are highly susceptible to ischemic injury,deplete their ATP stores faster than glial cells(e.g.,astrocytes),which have some energy reserves.
基金supported by the National Natural Science Foundation of China(Grant No.21771049,22071041,and 92256201)the Fundamental Research Funds for the Central Universities of China(Grant No.PA2020GDJQ0028 and PA2021GDSK0063).
文摘Static one-handed helical polymers can serve as an ideal catalytic platform toward chiral synthesis.As a demonstration of helical polyisocyanides in asymmetric catalysis,we report a novel strategy to facilitate asymmetric cooperative catalysis for the kinetic resolution of epoxides with TMSN_(3) using one-handed polyisocyanide-supported Co(III)-salen catalysts.Co(III)-salen is decorated with polyisocyanides to produce the polymer-supported catalyst P1-Co-N_(3).Owing to the rigid helical backbone of the polyisocyanide skeleton,spatially adjacent Co(III)-salen pendants are arranged with a distance of~1.2 nm so that the epoxide and TMSN_(3) can undergo dual activation in an amplified chiral environment.The catalytic performance is investigated via the kinetic resolution for a series of terminal epoxides through enantioselective ring-opening with TMSN_(3).P1-Co-N_(3) exhibits high catalytic activity and enantioselectivity,producing the desired products in high enantiomeric excesses and good yields at a low catalyst loading(0.6 mol%).In contrast,a small molecular control,S1-Co-N_(3),performs poorly owing to the absence of a preorganized catalytic dimer.Moreover,this polyisocyanide-based catalyst exhibits good functional group tolerance and stable activity in multiple recycles.To demonstrate its potential application in the asymmetric synthesis of chiral drugs,we conducted a gram-scale asymmetric synthesis ofβ-amino acid derivatives via this kinetic resolution method as the essential step.
基金supported by the National Natural Science Foundation of China(No.92261118,92161103,22071180).
文摘Photocatalytic splitting of water to produce hydrogen is a potential solution to alleviate environmental pollution and the energy crisis.It is shown here that H_(3)PMo_(12)O_(4)0(PMo_(12))as a co-catalyst with CdS nanosheets can form a well-designed composite photocatalyst without the aid of precious metals by microwave synthesis.A small loading of PMo_(12)(1.8%Mo)exhibits highly efficient photocatalytic perform-ance with a maximum hydrogen production of 5.7 mmol h^(−1)g^(−1),nearly six times higher than that of iso-lated CdS nanosheets.The charge transfer process in the photocatalytic system was further confirmed by XPS analysis,where PMo_(12)accelerated the separation of photogenerated carriers,shortened the charge transfer distance and substantially enhanced the photogeneration efficiency and stability of water clea-vage to hydrogen.This combination of polyoxometalates and CdS has promising applications and pro-vides a new way to develop efficient and novel photocatalysts for sustainable solar energy utilization strategies.
