Applied Magnetic Resonance最新文献_第7页

Knee Model Construction Using Deep Neural Networks with Boundary Information for Local SAR Estimation 利用带边界信息的深度神经网络构建膝关节模型，用于局部合成孔径雷达估算

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-06-03 DOI: 10.1007/s00723-024-01662-y

Liang Xiao, Hongjin Ren, Hangyu Zhou, Cangju Xing

{"title":"Knee Model Construction Using Deep Neural Networks with Boundary Information for Local SAR Estimation","authors":"Liang Xiao, Hongjin Ren, Hangyu Zhou, Cangju Xing","doi":"10.1007/s00723-024-01662-y","DOIUrl":"10.1007/s00723-024-01662-y","url":null,"abstract":"<div>The local specific absorption rate (SAR) is a key safety indicator in high-field MRI. Constructing a specific model for each patient is important for accurate estimation of local SAR. The aim of this study is to construct subject-specific knee models based on low-field images for realizing accurate local SAR estimation in high-field MRI systems (3T and 1.5T). The proposed method used two U-Net networks for tissue segmentation of knee joint and the classification results of the two networks were merged to generate the final models. Muscle has high dielectric properties and large volume, which have an important influence on the electromagnetic field distribution. To improve the accuracy of muscle segmentation, a U-Net making use of boundary information was used to segment muscle alone to overcome the problem of inhomogeneous intensity at the edge of the muscle region. Other tissues were segmented by another U-Net, which used a weighted loss function to mitigate the adverse influence of class imbalances between tissues. The proposed method was compared with other methods using manual delineation as the standard. Its muscle segmentation performance was better than that of the comparison methods. On the other hand, local SAR in 3T using models constructed by these methods was also evaluated through electromagnetic simulation separately. It was shown that the maximum SAR10g of the models constructed by the proposed method was much closer to that of manual delineation on the whole. These results validated the availability of the proposed method.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 7","pages":"663 - 685"},"PeriodicalIF":1.1,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141259783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Scavenger-Based Immobilized Rh and Ir Complexes in Hydrogenation of Propyne and Propene with Parahydrogen 丙炔和丙烯与对氢的加氢反应中基于清除剂的固定化 Rh 和 Ir 复合物

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-05-22 DOI: 10.1007/s00723-024-01660-0

Ivan V. Skovpin, Dudari B. Burueva, Larisa M. Kovtunova, Anna V. Nartova, Ren I. Kvon, Valerii I. Bukhtiyarov, Igor V. Koptyug

{"title":"Scavenger-Based Immobilized Rh and Ir Complexes in Hydrogenation of Propyne and Propene with Parahydrogen","authors":"Ivan V. Skovpin, Dudari B. Burueva, Larisa M. Kovtunova, Anna V. Nartova, Ren I. Kvon, Valerii I. Bukhtiyarov, Igor V. Koptyug","doi":"10.1007/s00723-024-01660-0","DOIUrl":"10.1007/s00723-024-01660-0","url":null,"abstract":"<div>The immobilization of dimeric [M2(COD)2(μ–Cl)2] complexes (M – Rh or Ir) by the interaction with -SH groups of 3-mercaptopropyl-functionalized silica gel leads to RhCl–S–SiO2 and IrCl–S–SiO2 catalysts active in hydrogenations of propene and propyne. Nuclear magnetic resonance enhancement in parahydrogen-induced polarization experiments was studied in a wide range of hydrogenations conditions (25–120 °C, 1.0–3.9 bar). The structural transformations were studied using ex situ X-ray photoelectron spectroscopy (XPS). It was established that IrCl–S–SiO2 demonstrated greater thermal stability in the hydrogenation of both propene and propyne in comparison with RhCl–S–SiO2. The beneficial effect of propyne was elucidated for thermal stability of studied catalysts and for the efficiency of the pairwise hydrogen addition. This can be explained by more efficient binding of the C≡C triple bond to an active center. The increase in reaction pressure typically leads to higher conversion in hydrogenations for both catalysts, but also decreases the temperatures sufficient for the reduction of anchored complexes with the formation of metal nanoparticles, which was confirmed by XPS.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 10","pages":"1275 - 1291"},"PeriodicalIF":1.1,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141110775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

PELDOR to the Metal: Cu(II)-Based Labels Put a New Spin on Distance Measurements PELDOR to the Metal：基于铜(II)的标签为距离测量注入了新的活力

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-05-18 DOI: 10.1007/s00723-024-01658-8

Joshua Casto, Shramana Palit, Sunil Saxena

{"title":"PELDOR to the Metal: Cu(II)-Based Labels Put a New Spin on Distance Measurements","authors":"Joshua Casto, Shramana Palit, Sunil Saxena","doi":"10.1007/s00723-024-01658-8","DOIUrl":"10.1007/s00723-024-01658-8","url":null,"abstract":"<div>Eighty years ago, the advent of electron paramagnetic resonance (EPR) revolutionized our ability to observe the physical world of unpaired electron spins. The inception of EPR spawned multiple scientific areas with a focus on discerning the roles of paramagnetic metals and organic radicals in an array of processes and materials. More recently, the emergence of site-directed spin labeling combined with distance measurement technology and molecular modeling has harnessed the power of EPR, to ‘watch proteins move’. Spin labels have enabled the measurement of distance constraints and site-specific dynamics in biomolecules to provide rich details of structure and structural changes that are tightly linked to biological function. Historically, nitroxide radicals are the most common spin labels. However, decades of method development and technological innovation have created a plethora of spin label types to extend the reach of EPR throughout the realm of biophysics. In this review we overview recent developments that improve the sensitivity of distance measurements using Cu(II) labels. These achievements over the last three years promise advancements in the ability of EPR to measure structural and dynamical constraints beyond what is possible using common spin labels. First, we briefly discuss pulsed and continuous-wave EPR techniques that discern the coordination of Cu(II) to monitor spin-labeling efficiency and binding in biological environments. Next, we outline the bottlenecks that impact sensitivity in pulsed dipolar spectroscopy and the strategic steps taken to remove these bottlenecks to collect distance measurements in hours. More precisely, we focus on the fast-spin phase memory relaxation time, the broad EPR spectrum due to anisotropy, and orientational selectivity effects inherent to Cu(II). Finally, we showcase the versatile application of Cu(II) spin labels in biological systems and the advantages of Cu(II) in pulsed dipolar spectroscopy to access nanomolar protein concentrations.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 9","pages":"889 - 922"},"PeriodicalIF":1.1,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141063385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Calculation of the Matrix Elements of the Long-Range Coulomb Interaction Comparison of the GTO and STO Approaches 远距离库仑相互作用矩阵元素的计算 GTO 和 STO 方法的比较

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-05-18 DOI: 10.1007/s00723-024-01659-7

O. A. Anikeenok

引用次数: 0

Exploring the Triplet State of Chlorophyll a in Mesoporous Silica Matrices by Time-Resolved EPR 通过时间分辨 EPR 探索介孔二氧化硅基质中叶绿素 a 的三重态

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-05-06 DOI: 10.1007/s00723-024-01657-9

Samuel Zatta, Andrea Calcinoni, Alessandro Agostini, Silvia Leccese, Thomas Onfroy, Claude Jolivalt, Alberto Mezzetti, Marco Bortolus, Donatella Carbonera

{"title":"Exploring the Triplet State of Chlorophyll a in Mesoporous Silica Matrices by Time-Resolved EPR","authors":"Samuel Zatta, Andrea Calcinoni, Alessandro Agostini, Silvia Leccese, Thomas Onfroy, Claude Jolivalt, Alberto Mezzetti, Marco Bortolus, Donatella Carbonera","doi":"10.1007/s00723-024-01657-9","DOIUrl":"10.1007/s00723-024-01657-9","url":null,"abstract":"<div>Chlorophyll is a pivotal molecule in photosynthesis due to its ability to absorb solar light and start the photochemical process. The chlorophyll triplet state is easily populated from the light-induced singlet excited state via Intersystem Crossing (ISC) and can react with oxygen generating singlet oxygen, posing a threat to the stability of chlorophyll, but also an opportunity for photodynamic therapy. Here, we focus on the study of the photo-physical properties of chlorophyll a and WSCP (Water-Soluble Chlorophyll Protein, a protein binding the pigment), which have been adsorbed in mesoporous silica matrices. We adopt SBA-15, a silica matrix with well-ordered hexagonal structure with pores of 70 Å of diameter. The triplet formed upon illumination in these systems is studied by time-resolved EPR spectroscopy. Analysis of the EPR spectra shows that the triplet state is very sensitive to the inclusion in the pores of SBA-15 modifying its spin polarization. Chl a in SBA-15 loses its central metal ion, while its structure remains unchanged if the mesoporous silica is previously soaked into a basic solution before Chl a adsorption, as revealed by its zero-field splitting parameters of the triplet state. WSCP is readily included in the silica matrix, but its embedded pigments are no longer protected by the protein core.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 12","pages":"1569 - 1585"},"PeriodicalIF":1.1,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00723-024-01657-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Synthesis of Yb3+-Doped Cs2NaScF6 Single Crystals and EPR Spectroscopy of the Dopant Yb3+ ion 掺杂 Yb3+ 的 Cs2NaScF6 单晶的合成和掺杂 Yb3+ 离子的 EPR 光谱分析

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-04-30 DOI: 10.1007/s00723-024-01656-w

M. L. Falin, V. A. Latypov, N. M. Khaidukov

引用次数: 0

Design of Inside-Out Magnetic Resonance Sensor Based on Coordinate Search Method 基于坐标搜索法设计内向外磁共振传感器

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-04-24 DOI: 10.1007/s00723-024-01649-9

Jiamin Wu, Zheng Xu, Yanhe Zhu, Yucheng He

{"title":"Design of Inside-Out Magnetic Resonance Sensor Based on Coordinate Search Method","authors":"Jiamin Wu, Zheng Xu, Yanhe Zhu, Yucheng He","doi":"10.1007/s00723-024-01649-9","DOIUrl":"10.1007/s00723-024-01649-9","url":null,"abstract":"<div>The application of inside-out magnetic resonance sensors has emerged as a focal point in soil moisture detection, offering a non-invasive approach crucial for evaluating soil physical structure. While existing inside-out magnetic resonance sensors with a unilateral structure can effectively measure the shallow soil layer, they fall short in assessing deeper soil layers (1–10 cm). However, the lack of optimal design and horizontal comparison among relevant sensors has impeded the widespread adoption of magnetic resonance sensors in soil moisture measurement. This paper addresses this gap by optimizing a magnetic resonance sensor with a dumbbell structure. The magnet structure is fine-tuned using a non-derivative optimization method, specifically the coordinate search, under practical engineering constraints to establish a uniform field in the region of interest. Employing the coordinate search method enhances the sensor’s relative signal-to-noise ratio (SNR) to its maximum. Artificial soil samples are then tested, and the T2 spectrum distribution reveals insights into water distribution characteristics across different pores.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 6","pages":"599 - 613"},"PeriodicalIF":1.1,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140664340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of Magnetic Resonance Imaging (MRI) Phantom With Arbitrary T1 Value Using Dextrin Hydrate 利用糊精水合物开发具有任意 T1 值的磁共振成像（MRI）模型

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-04-21 DOI: 10.1007/s00723-024-01655-x

Yusuke Sato, Daiki Ito, Norio Hayashi, Kouichi Ujita, Takayuki Suto, Haruyuki Watanabe, Yoshito Tsushima

{"title":"Development of Magnetic Resonance Imaging (MRI) Phantom With Arbitrary T1 Value Using Dextrin Hydrate","authors":"Yusuke Sato, Daiki Ito, Norio Hayashi, Kouichi Ujita, Takayuki Suto, Haruyuki Watanabe, Yoshito Tsushima","doi":"10.1007/s00723-024-01655-x","DOIUrl":"10.1007/s00723-024-01655-x","url":null,"abstract":"<div>To formulate the relationship between the dextrin hydrate concentration and T1 relaxation rate and create a magnetic resonance imaging (MRI) phantom with an arbitrary T1 value. Dextrin solution with nine different concentrations was prepared by dissolving 0–20 g (2.5 g increments) of dextrin in 25 g of purified water. The T1 values of the phantoms were measured using a 1.5 T MR scanner, and the relationship between the R1 value and dextrin concentration was regressed using linear and quadratic equations. Phantoms with concentrations adjusted to T1 values of 500, 1000, and 1500 ms were created from each regression equation, and the errors between the measured T1 and target values were evaluated. In addition, the temporal changes in the T1 and T2 values of the phantoms were also evaluated. The T1 and T2 values ranged from 367.4 ± 14.1 to 2577.6 ± 76.5 ms and 20.0 ± 0.9 to 1805.3 ± 8.3 ms, respectively. The linear and quadratic regression equations were (y=2.9631x+0.2043) and (y=1.8295{x}^{2}+1.4995x+0.37), with coefficients of determination of 0.9763 and 0.9954, respectively. The maximum errors were 12.3% and 2.1% for the linear and quadratic equations, respectively. The T1 value was maintained at a fluctuation rate of approximately 10% during the first 4 weeks. The T2 value decreased by approximately 20% after 4 weeks. MRI phantoms with arbitrary T1 values in the range of 500–1500 ms with an error within 2.1% can be created using dextrin, which can be used as human tissue-equivalent MRI phantoms for T1 of the grey or white matter of the brain, liver, pancreas, spleen, and prostate.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 5","pages":"497 - 507"},"PeriodicalIF":1.1,"publicationDate":"2024-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140628410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electron Spin Dynamics of the Photoexcited Triplet States of Bromoperylenebisimide Compounds: Computation and Analysis of the Electron Spin Polarization Evolution in TREPR Spectra 溴过二亚胺化合物光激发三重态的电子自旋动力学：TREPR 光谱中电子自旋极化演变的计算与分析

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-04-20 DOI: 10.1007/s00723-024-01654-y

A. Mambetov, A. Sukhanov, Xue Zhang, Jianzhang Zhao, V. Voronkova

{"title":"Electron Spin Dynamics of the Photoexcited Triplet States of Bromoperylenebisimide Compounds: Computation and Analysis of the Electron Spin Polarization Evolution in TREPR Spectra","authors":"A. Mambetov, A. Sukhanov, Xue Zhang, Jianzhang Zhao, V. Voronkova","doi":"10.1007/s00723-024-01654-y","DOIUrl":"10.1007/s00723-024-01654-y","url":null,"abstract":"<div>The dynamics of the photogenerated triplet electron spin polarization (ESP) of two perylenebisimide (PBI) derivatives, PBI-2Br and PBI-Br-NH, is studied by the time-resolved electron paramagnetic resonance (TREPR). The ESP inversion in the triplet TREPR spectra of two compounds is detected at delays after the laser pulse (DAF) of ~ 500–900 ns. A fairly efficient algorithm for the exact numerical solution of the equation of motion of the spin density matrix of an ensemble of photoexcited triplets taking into account the anisotropy of the decay rates of sublevels of the triplet state, spin–lattice and spin–spin relaxations is elaborated in order to analyze the ESP inversion of TREPR spectra. The calculated time evolution of the TREPR spectra and its fitting experimental ones shows that even a slight difference in decay rates for the triplet sublevels of PBI-2Br results in the ESP inversion in the TREPR spectra already at DAF of ~ 500 ns. At the same time, decay rates ( τX−1 = 4 µs−1; τY−1 = 4.4 µs−1; τZ−1 = 3.3 µs−1) are higher than those for the available examples of the ESP inversion of the triplet TREPR spectra. The replacement of a Br atom by NH leads to noticeable changes in the photoinduced properties of the triplet including decay rates (τX−1 = 1.25 µs−1; τY−1 = 0.125 µs−1; τZ−1 = 0.125 µs−1). PBI-Br-NH is characterized by an axial decay rate anisotropy with τx−1, which is ten times higher than τY−1 and τZ−1. The trend in the triplet lifetime change obtained from the TREPR spectra is consistent with the data of the nanosecond transient absorption spectra.</div>","PeriodicalId":469,"journal":{"name":"Applied Magnetic Resonance","volume":"55 12","pages":"1553 - 1567"},"PeriodicalIF":1.1,"publicationDate":"2024-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140630286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental Studies of Power-Saturated Spin Modes of Nitroxides in Liquids 1 液体中氮氧化物功率饱和自旋模式的实验研究 1

IF 1.1 4区物理与天体物理

Applied Magnetic Resonance Pub Date : 2024-04-19 DOI: 10.1007/s00723-024-01651-1

Barney L. Bales, Miroslav Peric, Robert N. Schwartz

引用次数: 0