Journal of Magnetic Resonance, Series A最新文献_第10页

ADRF-CP Surface-Coil Spectroscopy of Synthetic Calcium Phosphates and Bone Mineral 合成磷酸钙和骨矿物的ADRF-CP表面线圈光谱

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0152

Chandrasekhar Ramanathan , Yaotang Wu , Bettina Pfleiderer , Martin J. Lizak , Leoncio Garrido , Jerome L. Ackerman

{"title":"ADRF-CP Surface-Coil Spectroscopy of Synthetic Calcium Phosphates and Bone Mineral","authors":"Chandrasekhar Ramanathan , Yaotang Wu , Bettina Pfleiderer , Martin J. Lizak , Leoncio Garrido , Jerome L. Ackerman","doi":"10.1006/jmra.1996.0152","DOIUrl":"10.1006/jmra.1996.0152","url":null,"abstract":"<div>Proton to phosphorus-31 cross polarization via adiabatic demagnetization in the rotating frame (ADRF-CP) has been used, in conjunction with a surface coil, to detect monohydrogen phosphate (acid phosphate) ions in the presence of a large background of nonprotonated phosphate (orthophosphate) ions in porcine bone and synthetic calcium phosphates. Transient oscillations were observed in the transfer of polarization between the proton dipolar and phosphorus Zeeman nuclear-spin reservoirs at short times after the initiation of thermal contact. The oscillations were observed in all samples, including bone. Orthophosphate suppression was achieved by detecting the signal when the orthophosphate oscillation was passing through zero, and by adjusting the phosphorus RF field to achieve optimal cross polarization with the proton local fields of the acid phosphate ions. ADRF-CP techniques deposit less RF power than traditional spin-lock CP techniques, and are hence compatible within vivoapplication. As the ratio of the protonated to nonprotonated phosphate can be used as a marker for bone-mineral maturity, ADRF-CP spectroscopy creates the possibility of characterizing bone-mineral dynamicsin vivoby solid-state NMR.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"121 2","pages":"Pages 127-138"},"PeriodicalIF":0.0,"publicationDate":"1996-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0152","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90510807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

The NMR Spectra of Samples Dissolved in Liquid-Crystalline Phases. Automatic Analysis with the Aid of Multiple-Quantum Spectra 液相溶解样品的核磁共振谱。借助多量子光谱的自动分析

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0153

G. Celebre , F. Castiglione , M. Longeri , J.W. Emsley

引用次数: 16

Global Analysis of Microwave-Induced Delayed Phosphorescence of Photoexcited Triplet States 微波诱导光激发三重态延迟磷光的全局分析

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0158

Andrzej Ozarowski, Jie Q. Wu, August H. Maki

{"title":"Global Analysis of Microwave-Induced Delayed Phosphorescence of Photoexcited Triplet States","authors":"Andrzej Ozarowski, Jie Q. Wu, August H. Maki","doi":"10.1006/jmra.1996.0158","DOIUrl":"10.1006/jmra.1996.0158","url":null,"abstract":"<div>The microwave-induced delayed phosphorescence (MIDP) responses of several molecules in their excited triplet state are analyzed globally by least-squares minimization of the residuals, χ2. The analysis considers not only the initial amplitudes of the MIDP responses which has been customary in the past, but also all data points (up to about 20,000) contained in a data set consisting of all three zero-field transitions and a range of delay times. It is shown that global fitting of the datacannotbe carried out successfully without including both sublevel decay to the ground singlet state and spin–lattice relaxation (SLR). Thus a complete data set containing at least two of the zero-field transitions when analyzed globally yields both sublevel decay constants and the SLR rate constants. Results are reported for tryptophan (Trp), 5-hydroxytryptophan (5-Htrp), the anion of 5-Htrp obtained by ionization of the hydroxyl proton, and 7-azatryptophan (7-Atrp). It is found that theTzsublevel (zis the out-of-plane axis) decays principally by SLR even at about 1.2 K;kz= 0 within experimental error (≈±0.01 s−1) except for 5-Htrp anion, where it is measurable and is the smallest of thekvalues. For each triplet state, except for 5-Htrp anion, SLR is least efficient between theTxandTysublevels. This relaxation process requires an angular momentum component alongz. Since thezcomponent of spin–orbit coupling is the weakest one in3(π, π*) states, the van Vleck relaxation process is suggested for Trp, 5-Htrp, and 7-Atrp. For the 5-Htrp anion, the most efficient SLR occurs betweenTxandTy, suggesting a different mechanism, possibly direct phonon modulation of the zero-field splittings.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"121 2","pages":"Pages 178-186"},"PeriodicalIF":0.0,"publicationDate":"1996-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0158","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78381721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Echo-Planar-Imaging Studies of Turbulent Flow 紊流的回波平面成像研究

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0160

J.C. Gatenby, J.C. Gore

引用次数: 27

Two-Dimensional Isotropic NMR of Quadrupole Nuclei in Solids 固体中四极核的二维各向同性核磁共振

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0163

Ago Samoson

引用次数: 24

Multinuclear NMR Imaging of11B Quadrupolar Solids with the Fringe-Field Method 用条纹场法对11b四极性固体进行多核磁共振成像

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0165

E.W. Randall , D.G. Gillies

引用次数: 11

Pulse-Sequence Optimization with Analytical Derivatives. Application to Deuterium Decoupling in Oriented Phases 脉冲序列的解析导数优化。定向相中氘解耦的应用

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0157

T.O. Levante, T. Bremi, R.R. Ernst

引用次数: 20

Field-Dependent Proton NMR Relaxation in Aqueous Solutions of Ni(II) Ions. A New Interpretation Ni(II)离子水溶液中的场相关质子核磁共振弛豫。新的解读

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0149

J. Svoboda , T. Nilsson , J. Kowalewski , P.-O. Westlund , P.T. Larsson

{"title":"Field-Dependent Proton NMR Relaxation in Aqueous Solutions of Ni(II) Ions. A New Interpretation","authors":"J. Svoboda , T. Nilsson , J. Kowalewski , P.-O. Westlund , P.T. Larsson","doi":"10.1006/jmra.1996.0149","DOIUrl":"10.1006/jmra.1996.0149","url":null,"abstract":"<div>A new model is presented for nuclear-spin relaxation in paramagnetic transition metal complexes in solution, allowing the electron-spin relaxation to be outside the Redfield limit. The novel feature is that the transient zero-field splitting (ZFS), modulated by distortions of the solvation shell, is allowed to be of rhombic rather than cylindrical symmetry. The model, which assumes that the static ZFS is absent, is applicable to aqueous solutions of transition metal ions. The magnetic-field dependence of the proton spin–lattice relaxation rate enhancement in aqueous solution has been investigated, and calculations are presented for anS= 1 system such as Ni2+(aq), using different degrees of rhombicity of the ZFS and different motional conditions (Redfield limit and slow-motion regime). The new model is also applied to fit the previously reported data for the field dependence of proton relaxation in aqueous solution of Ni(ClO4)2at low pH [J. Kowalewski, T. Larsson, and P.-O. Westlund,J. Magn. Reson.74, 56 (1987)]. The inclusion of rhombicity, motivated by recent theoretical work, provides a model which performs as well as the earlierad hocmodel.</div>","PeriodicalId":16165,"journal":{"name":"Journal of Magnetic Resonance, Series A","volume":"121 2","pages":"Pages 108-113"},"PeriodicalIF":0.0,"publicationDate":"1996-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1006/jmra.1996.0149","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79199729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 24

Long-Range Water Transport and Self-Diffusion in Zeolite 4A Powder Beds 沸石4A粉床中水的远程输运和自扩散

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0154

P.D.M. Hughes , P.J. McDonald , E.G. Smith

引用次数: 10

A Window on the Motion of the Nuclear Spins 核自旋运动的窗口

Journal of Magnetic Resonance, Series A Pub Date : 1996-08-01 DOI: 10.1006/jmra.1996.0164

Helmut Sengstschmid , Ray Freeman

引用次数: 6