Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve suc...Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating frame.In this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic demagnetization.We further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically demagnetized.Our analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S spins.In addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized signals.It is shown by both static and magic-angle-spinning(MAS)NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP schemes.Various samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.展开更多
Water plays an important role in many essential biological processes of membrane proteins in hydrated lipid environments.In general,the 1H polarization transfers berween water molecules and site--specific protons in p...Water plays an important role in many essential biological processes of membrane proteins in hydrated lipid environments.In general,the 1H polarization transfers berween water molecules and site--specific protons in proteins can be classified as coherent(via dipolar spin diffusion)and incoherent(via chemical exchange and nuclear Overhauser effect)transfers.Solid-state NMR is the technique of choice for studying such water-protein interactions in membrane-bound proteins/peptides through the detection of'H polarization transfers from water to the proteins.These polarization transfer mechanisms often exist simultaneously and are difficult to quantify individually.Here,we review water-protein polarization transfer techniques in solid state NMR with a focus on the recent progress for the direct detection of site-specific kinetic water-protein chemical exchange processes on the sub-millisecond time scale in membrane-bound proteins.The measurements of the pure chemical exchange ki-netics provide a unique opportunity to understand the role that water plays in the structure-function relationships of membrane bound species at the water-bilayer interface.In addi-tion,the perspective of chemical exchange saturation transfer(CEST)experiments in membrane-bound proteins/peptides is further discussed.展开更多
In pursuit of higher energy density,lower cost,longer lifespan and safety,remarkable research efforts have been taken to innovate various types of energy storage materials/devices,especially metal-ion batteries such a...In pursuit of higher energy density,lower cost,longer lifespan and safety,remarkable research efforts have been taken to innovate various types of energy storage materials/devices,especially metal-ion batteries such as Li-ion batteries(LIBs).One of the major challenges is to elucidate the working mechanisms and/or the controlling factors of any new material in a full battery,which requires adequate characterization/diagnosis techniques.Among the numerous electrochemical ex-situ and insitu characterization techniques,magnetic resonance techniques,including nuclear magnetic resonance(NMR),magnetic resonance imaging(MRI)and electron paramagnetic resonance(EPR),are unique in terms of providing structural information at the atomic level and real-time phase and morphology evolution and characterizing ionic motion at various timescales.This special issue is dedicated to an editorial and a selection of papers on the theme of investigating energy storage materials/devices using magnetic resonance techniques.As the guest editors of this special issue,we are honored to introduce the following high-quality research articles and review articles.展开更多
基金supported by the NSF Cooperative Agreement DMR-1644779the State of Florida.X.H.P.acknowledges the supports from the National Key R&D Program of China(Grants No.2018YFA0306600)+1 种基金the National Science Foundation of China(Grants No.11927811,12150014)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000).
文摘Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating frame.In this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic demagnetization.We further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically demagnetized.Our analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S spins.In addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized signals.It is shown by both static and magic-angle-spinning(MAS)NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP schemes.Various samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.
基金This work was supported by NIH Grants AI023007 and GM122698All NMR experiments were carried out at the National High Magnetic Field lab(NHMFL)supported by the NSF Cooperative Agreement DMR-1644779 and the State of Florida.
文摘Water plays an important role in many essential biological processes of membrane proteins in hydrated lipid environments.In general,the 1H polarization transfers berween water molecules and site--specific protons in proteins can be classified as coherent(via dipolar spin diffusion)and incoherent(via chemical exchange and nuclear Overhauser effect)transfers.Solid-state NMR is the technique of choice for studying such water-protein interactions in membrane-bound proteins/peptides through the detection of'H polarization transfers from water to the proteins.These polarization transfer mechanisms often exist simultaneously and are difficult to quantify individually.Here,we review water-protein polarization transfer techniques in solid state NMR with a focus on the recent progress for the direct detection of site-specific kinetic water-protein chemical exchange processes on the sub-millisecond time scale in membrane-bound proteins.The measurements of the pure chemical exchange ki-netics provide a unique opportunity to understand the role that water plays in the structure-function relationships of membrane bound species at the water-bilayer interface.In addi-tion,the perspective of chemical exchange saturation transfer(CEST)experiments in membrane-bound proteins/peptides is further discussed.
文摘In pursuit of higher energy density,lower cost,longer lifespan and safety,remarkable research efforts have been taken to innovate various types of energy storage materials/devices,especially metal-ion batteries such as Li-ion batteries(LIBs).One of the major challenges is to elucidate the working mechanisms and/or the controlling factors of any new material in a full battery,which requires adequate characterization/diagnosis techniques.Among the numerous electrochemical ex-situ and insitu characterization techniques,magnetic resonance techniques,including nuclear magnetic resonance(NMR),magnetic resonance imaging(MRI)and electron paramagnetic resonance(EPR),are unique in terms of providing structural information at the atomic level and real-time phase and morphology evolution and characterizing ionic motion at various timescales.This special issue is dedicated to an editorial and a selection of papers on the theme of investigating energy storage materials/devices using magnetic resonance techniques.As the guest editors of this special issue,we are honored to introduce the following high-quality research articles and review articles.