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ENGINEERING (1199 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 217)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 19)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 35)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 27)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 8)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 7)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 38)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 177)
Composites Part B : Engineering     Hybrid Journal   (Followers: 222)
Composites Science and Technology     Hybrid Journal   (Followers: 165)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 25)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 41)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  

        1 2 3 4 5 6 | Last

Journal Cover Applied Magnetic Resonance
  [SJR: 0.358]   [H-I: 34]   [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1613-7507 - ISSN (Online) 0937-9347
   Published by Springer-Verlag Homepage  [2329 journals]
  • Erratum to: Force-detected ESR Measurements in a Terahertz Range up to
           0.5 THz and Application to Hemin
    • Authors: Tsubasa Okamoto; Hideyuki Takahashi; Eiji Ohmichi; Hitoshi Ohta
      Pages: 445 - 445
      PubDate: 2017-04-18
      DOI: 10.1007/s00723-017-0881-1
      Issue No: Vol. 48, No. 5 (2017)
  • Broadband Excitation by Method of Double Sweep
    • Authors: Navin Khaneja; Ashutosh Kumar
      Abstract: The paper describes the design of broadband excitation pulses in high resolution nuclear magnetic resonance (NMR) by method of double sweep. We first show the design of a pulse sequence that produces broadband excitation to the equator of Bloch sphere with phase linearly dispersed as frequency. We show how this linear dispersion can then be refocused by nesting free evolution between two adiabatic inversions (sweeps). We then show how this construction can be generalized to exciting arbitrary large bandwidths without increasing the peak rf-amplitude and by incorporating more adiabatic sweeps. Finally, we show how the basic design can then be modified to give a broadband x rotation over arbitrary large bandwidth and with limited rf-amplitude. Experimental excitation profiles for the residual HDO signal in a sample of \(99.5\%\) D \(_2\) 0 are displayed as a function of resonance offset. Application of the excitation is shown for \(^{13}\) C excitation in a labelled sample of alanine.
      PubDate: 2017-05-18
      DOI: 10.1007/s00723-017-0894-9
  • Structural Analysis of Relaxation Curves in MRI
    • Authors: Alexey V. Protopopov
      Abstract: In magnetic resonance imaging, the gradient recalled echo sequence preserves information about spatial heterogeneities of magnetic field within a voxel, providing additional opportunity for classification of biological tissues. All the information, composed of physically meaningful parameters, like proton density, spin–spin relaxation time T 2, gradients of magnetic field and spin–spin relaxation, effective relaxation time \(T_{2}^{*}\) , and many others, is encoded in the shape of a relaxation curve, which is more complicated than a pure monoexponent, traditionally observed in spin echo sequences. The previous work [A. Protopopov, Appl. Magn. Reason. 48, 255-274 (2017)], introduced the theory and basic algorithms for separation of those parameters. The present work further expands this theory to the case of spin–spin relaxation gradients, improves reliability of the algorithms, introduces physical explanation of the phenomenon previously known as “multiexponentiality”, and presents new validation of the algorithms on volunteers. The entire approach may be named the structural analysis of relaxation curves.
      PubDate: 2017-05-17
      DOI: 10.1007/s00723-017-0890-0
  • The Medical 1 H-MRS Analysis of Edible Vegetable Oils Rancidity: Focus on
           the Saturated/Unsaturated Fatty Acids (Bond) Change
    • Authors: Onseok Lee; Suk-Jun Lee; Seung-Man Yu
      Abstract: The purpose of this study was to investigate the usefulness of medical magnetic resonance spectroscopy analysis methods for assessment of edible oil rancidity. The four edible oils including soybean oil, olive oil, grape seed oil, and sunflower oil were selected for evaluating rancidity (cooking counts/time, exposure time in air). The total lipid ((–CH2–) n /noise), total saturated fatty acid (TSFA), total unsaturated fatty acid (TUSFA), total unsaturated bond (TUSB), and polyunsaturated bond (PUSB) were quantified by separating each peak area of –CH3, (–CH2–) n , –CH2–C=C–CH2–, =C–CH2–C=, and –CH=CH– by –CH3 by 1H-magnetic resonance spectroscopy (MRS) analysis. The change in fatty acid (bond) according to the cooking counts/time increased for all fatty acids (bond) in soybean oil and grape seed oil. In olive oil, all fatty acids (bond) decreased overall, while sunflower oil showed a decrease in TSFA and PUSB and an increase in TUSFA and TUSB. The soybean, grape seed, and sunflower oils showed increased TUSB, TUSFAB, and PUSB with exposure to air after cooking once, while olive oil showed hardly any changes in fatty acids according to the exposure time to air after cooking. It will be necessary to choose a method that minimizes changes in fatty acids by fully understanding the characteristics of the selected edible oil to prevent not only a change in fatty acids during cooking, but also an increase in TSFA.
      PubDate: 2017-05-16
      DOI: 10.1007/s00723-017-0893-x
  • Quantitative Effect of Magnetic Field Strength on PEGylated
           Superparamagnetic Iron Oxide Nanoparticles
    • Authors: Amin Farzadniya; Fariborz Faeghi; Saeed Shanehsazzadeh
      Abstract: With promising applications of superparamagnetic iron oxide nanoparticles (SPIO) in magnetic resonance imaging (MRI) and targeted monitoring of molecular and cellular processes, many different samples of these nanoparticles (NPs) with different compositions synthesized each year. The main challenge in this way is to generate enough contrast that could be traceable on images. In order to compensate for the low quantity of contrast agents in desired sites, surface engineering has to be done to enhance relaxation rates. As many factors such as magnetic field strength can affect relaxation rates of NPs, knowledge of the relation between field strength and relaxation rates is essential to compare results of different fields and choosing an optimum agent for a specific field. In this study, we evaluate the effects of magnetic field strengths of 0.35, 1.5, and 3 T on relaxation rates of PEGylated SPIOs. Longitudinal and transverse relaxation rates of all samples with various concentrations were analyzed quantitatively on appropriate spin–echo sequences. Our results suggest that the increasing of the field strength leads to a marked decrease of longitudinal relaxivity. In the case of transverse relaxivity, all NPs showed an increase between 0.35 and 1.5 T. Upon further increasing the field strength, relaxation rates only slightly increased except for two samples that showed saturation.
      PubDate: 2017-05-15
      DOI: 10.1007/s00723-017-0880-2
  • CP MAS Kinetics Study of Ionic Liquids Confined in Mesoporous Silica:
           Convergence of Non-Classical and Classical Spin Coupling Models
    • Authors: Vytautas Klimavicius; Laurynas Dagys; Vladimir Chizhik; Vytautas Balevicius
      Abstract: The high data point density measurements of 1H→11B cross-polarization (CP) kinetics upon magic-angle spinning (MAS) of [bmim][BF4] confined in mesoporous SBA-15 and MCM-41 were carried out. The complex shaped 11B CP MAS signals were observed in both silica and decomposed into two Lorentz components. This points towards the possibility of bimodal distribution of [bmim][BF4] in the studied confinements. The convergence of classical and non-classical spin coupling models was deduced processing CP kinetic curves. A good fit of the theoretical curves to the experimental data was achieved using both models without any non-random deviations between theory and experiment to appear. The convergence of spin coupling models was discussed in terms of relatively high mobility of BF4 − anion respect to the cation and the dynamics of anions in pores. These factors delete the borders between spin clusters. The spin diffusion along the pore surfaces in MCM-41 is more than twice faster than in SBA-15.
      PubDate: 2017-05-15
      DOI: 10.1007/s00723-017-0891-z
  • NMR Relaxation Efficiency of Aqueous Solutions of Composite Mg x Zn y Fe
           3−x−y O 4 Nanoparticles
    • Authors: Yu. V. Bogachev; A. V. Nikitina; A. A. Kostina; V. A. Sabitova; V. V. Pankov; T. G. Shutava; E. G. Petrova; D. A. Kotsikau; V. O. Natarov; K. S. Livanovich
      Abstract: The results of proton nuclear magnetic resonance (NMR) relaxation measurements in aqueous solutions of Mg x Zn y Fe3−x−y O4 magnetite-based composite magnetic nanoparticles (MNPs) are discussed. It is shown that their transverse relaxivity (relaxation efficiency) r 2 is significantly higher than the longitudinal relaxivity r 1 and depends on the magnetic nanoparticles composition and preparation method. A polyelectrolyte layer adsorbed on the nanoparticle surface increases both relaxivity values. The carbonate-synthesized MNPs possess higher values of r 2 and r 1 as compared with base-precipitated complex oxides. Relaxivity r 2 is shown to be affected by stability of MNPs in aqueous solutions and the aggregation behavior apparently can be assessed through the NMR relaxation measurements.
      PubDate: 2017-05-11
      DOI: 10.1007/s00723-017-0889-6
  • ESR Study of Y 2 SiO 5 :Nd 143 Isotopically Pure Impurity Crystals for
           Quantum Memory
    • Authors: A. A. Sukhanov; V. F. Tarasov; R. M. Eremina; I. V. Yatsyk; R. F. Likerov; A. V. Shestakov; Yu. D. Zavartsev; A. I. Zagumennyi; S. A. Kutovoi
      Abstract: Two Y2SiO5 single crystals doped with 0.001 at.% of the 143Nd3+ ion (sample I containing the only 28Si isotope) and (sample II with the natural abundance of silicon isotopes) were studied using magnetic resonance methods. The spin–spin and spin–lattice relaxation times were measured at 9.7 GHz between 4 and 10 K. It is established that three relaxation processes describe temperature dependences of the spin–lattice relaxation for both crystals. They are one-phonon, two-phonon Raman and two-phonon Orbach–Aminov relaxation processes. It is established that temperature dependence of spin–spin relaxation time differs for different hyperfine components of the electron paramagnetic resonance spectrum of neodymium ions and depends on the kind of the neodymium isotope (143Nd or 145Nd).
      PubDate: 2017-05-10
      DOI: 10.1007/s00723-017-0888-7
  • The Effect of Hydroxynaphtazarin Derivatives on Decrease of Ischemic Area
           After Damage Focal Cerebral Blood Circulation
    • Abstract: 7-Ethyl-2,3-diglutathionyl-6-hydroxynaphthazarin (GluNaz, 1a) can be a protector of the rat brain under ischemia. The effect of hydroxynaphtazarin derivative 1a was estimated. The focal ischemia by occlusion of middle cerebral artery (MCAo) was used. Conjugate 1a kept life of more then 30% of rats after treatment. Studied compounds did not render additional changes of arterial pressure before and within 3 h after operation. The injection of 1a in a concentration exceeding a therapeutic dose more than by ten times did not lead to an increase in heart rate in intact animals. The behavioral reactions of rats after occlusion showed an increase of cognitive frustration. Like 7-ethyl-2,3,6-trihydroxynaphthazarin (Ech, 1b) (Russian Pat. RU 2266737, 1999 [3]), GluNaz reduced the region of cytotoxic edema in rat brain after treatment. The recovering effect of 1a begins to improve within 48 h and 1b—within 72 h. Magnetic resonance imaging allows a detailed dynamic study of the effect of the compounds in our model of an ischemic stroke. So, the conjugate 1a studied can be potential medicine for the treatment of ischemic injury of a brain.
      PubDate: 2017-05-06
      DOI: 10.1007/s00723-017-0887-8
  • Investigation of Coherence Time of a Nitrogen-Vacancy Center in Diamond
           Created by a Low-Energy Nitrogen Implantation
    • Authors: Chathuranga Abeywardana; Zaili Peng; Laura C. Mugica; Edward Kleinsasser; Kai-Mei C. Fu; Susumu Takahashi
      Abstract: A nitrogen-vacancy (NV) center in diamond has been investigated extensively because of its promising spin and optical properties for applications to nanoscale magnetic sensing and magnetic resonance of magnetic elements outside the diamond. For those applications, a long decoherence time and positioning of an NV center on the diamond surface are desired. Here, we report the creation of NV centers near the diamond surface using a 3 keV nitrogen implantation and the coherence property of the created NV center.
      PubDate: 2017-04-25
      DOI: 10.1007/s00723-017-0885-x
  • Using Terahertz Waves to Identify the Presence of Goethite via
           Antiferromagnetic Resonance
    • Authors: S. G. Chou; P. E. Stutzman; V. Provenzano; R. D. McMichael; J. Surek; S. Wang; D. F. Plusquellic; E. J. Garboczi
      Abstract: Virtually every corrosion detection method reports only the presence of a material phase that denotes probable corrosion, not its spectral signature. A signature specific to the type of iron oxide corrosion product would not only confirm the presence of corrosion but also provide insight into the environment of its formation. To identify the unique spectral signature of a commonly occurring corrosion product, goethite (α-FeOOH), we performed high-resolution terahertz (THz) absorption loss measurements on a polycrystalline mineral sample of goethite, scanning from 0.045 to 1.5 THz. We report two distinct temperature-dependent absorption peaks that extend from 4.2 to 425 K. By combining X-ray diffraction and magnetic characterization on this large crystallite-sized goethite sample, we derived a Neél transition temperature of 435 K, below which the sample is antiferromagnetic. We interpret these absorption peaks as magnon transitions of the antiferromagnetic resonances, allowing precise identification of goethite, a common iron corrosion product and geological mineral, via two terahertz absorption peaks over this temperature range. This measurement technique has the potential for detecting iron-bearing oxides originating from corrosion occurring underneath layers of polymeric products and other protective coatings that can be easily penetrated by electromagnetic waves with frequencies on the order of 1 THz. Furthermore, the combined X-ray and magnetic characterization of this sample, which had a large crystallite size, also improved the previously established relationship between the Néel transition temperature and the inverse mean crystallite dimension in the [111] direction. Our results provide end-case peaks which, compared with goethite samples of smaller crystallite size and purity, will enable the extension of this non-destructive evaluation technique to real corrosion applications.
      PubDate: 2017-04-24
      DOI: 10.1007/s00723-017-0884-y
  • MRI Study of Liesegang Patterns: Mass Transport and Banded Inorganic
           Phase Formation in Gel
    • Authors: Nikola Klanicová; Aneta Malá; Ondřej Macíček; Josef Zeman; Zenon Starčuk
      Abstract: A new non-optic method for the study of Liesegang patterns was tested. Liesegang patterns are periodically banded precipitates produced by the reaction–diffusion process, mostly occurring in geology. The Liesegang experiment (5.5 M NH4OH, gelatin matrix with 0.4 M MgSO4) was monitored using a 9.4 T magnetic resonance imaging (MRI) system, allowing the acquisition of sample images in any location and orientation without interfering with the process studied. The development of patterns in a gel matrix was observed for 7 days after starting the reaction. Qualitative data (T 2- and T 2*-weighted images) and quantitative T 2 maps were acquired. Preliminary experiments show that MRI is able to distinguish the regions between the precipitated bands and the structural changes in the gel matrix during the reaction. A damaged gel matrix was measured to reveal the effect of the initial reagent-gel contact area. MRI study of Liesegang patterns provides empirical data which can be used in theoretical model testing.
      PubDate: 2017-04-20
      DOI: 10.1007/s00723-017-0882-0
  • Quantitative Susceptibility Mapping of the Substantia Nigra in
           Parkinson’s Disease
    • Authors: Xinxin Zhao; Hedi An; Tian Liu; Nan Shen; Binshi Bo; Zhuwei Zhang; Pengfei Weng; Meining Chen; Mengchao Pei; Yi Wang; Dongya Huang; Jianqi Li
      Abstract: The purpose of this study was to evaluate the sensitivities of quantitative susceptibility mapping (QSM) and R2* mapping in clinical diagnoses of Parkinson’s disease (PD). QSM images and R2* maps from 29 patients with PD and 25 healthy controls were obtained on a clinical 3T magnetic resonance imaging (MRI) system using a three-dimensional multi-echo gradient-echo sequence. Two-tailed t tests and receiver operating characteristic curves analyses were applied to the mean values of QSM and R2* of the two groups. In the PD group, a two-tailed Pearson correlation analysis was used to investigate the correlations between MRI measures (susceptibility and R2* values) and the Unified Parkinson’s Disease Rating Scale-III (UPDRS-III) score. In the substantia nigra (SN), a significant difference between patients with PD and healthy controls was found on QSM (154.80 ± 43.36 vs. 127.50 ± 21.05 ppb, P = 0.006) but not on R2* mapping. The receiver operating characteristic curves showed that QSM was more sensitive than R2* mapping to distinguish PD patients from healthy controls, with areas under the curve equal to 0.68 and 0.51, respectively. The UPDRS-III motor scores did not correlate with mean susceptibility or R2* values in the PD group. In conclusion, QSM is a more accurate and sensitive method than R2* mapping to detect the pathologic changes in the SN of patients with PD.
      PubDate: 2017-04-06
      DOI: 10.1007/s00723-017-0877-x
  • Floquet Hamiltonian and Entanglement in Spin Systems in Periodic Magnetic
    • Authors: E. B. Fel’dman; D. E. Feldman; E. I. Kuznetsova
      Abstract: We investigate entanglement in a two-spin system with the dipole–dipole interaction in the multi-pulse spin locking nuclear magnetic resonance (NMR) experiment. We discover a conflict between an exact solution and the standard approximation employing a time-independent effective Floquet Hamiltonian. While the exact solution shows nonzero entanglement in the system, the perturbative Floquet approach predicts that entanglement is absent. The failure of the Floquet method is explained by the multivaluedness of the Floquet Hamiltonian. Correct results can only be obtained with a proper choice of the branch of the Hamiltonian. The same issue is present in other applications of the Floquet theorem in the perturbation theory beyond NMR.
      PubDate: 2017-04-05
      DOI: 10.1007/s00723-017-0879-8
  • Design and Demonstration of Four-Channel Received Coil Arrays for
           Vertical-Field MRI
    • Authors: Qiaoyan Chen; Yajie Xu; Yan Chang; Xiaodong Yang
      Abstract: The layout of radio-frequency received coils is related to signal-to-noise ratio (SNR) in magnetic resonance imaging (MRI). In this paper, different structures of four-channel received coil arrays for vertical-field MRI are constructed and optimized by establishing the relationship between coil geometry and SNR to achieve a high SNR and a uniform SNR distribution in the region of interest (ROI). Then, the SNR distributions of three optimized configurations, including rectangular loops, non-definite shape surface coils, and solenoid loops as the main unit, are simulated and compared. The four-channel coil of solenoid loops as the main unit has been found to have the best performance with the highest mean SNR in the ROI when imaging without acceleration. In addition, g-factor and 2D SENSE SNR in yoz-plane are simply analyzed, which show a sharp decrease in SNR for all the coils. Finally, all the coils are manufactured and operated at a 0.5 T permanent magnet MRI system with phantom and joint imaging experiments. Using pixel-by-pixel manner to evaluate SNR map, the experimental results are consistent with the simulation results, while parallel imaging experiment results show that the major consideration in low field MRI is the improvement of SNR value and uniformity rather than that of the imaging speed. As different constructions of four-channel received coils are investigated, we have found the most effective configuration with high and uniform SNR for vertical-field MRI.
      PubDate: 2017-04-03
      DOI: 10.1007/s00723-017-0878-9
  • Singular Value Decomposition Using Jacobi Algorithm in pMRI and CS
    • Authors: Sohaib A. Qazi; Abeera Saeed; Saima Nasir; Hammad Omer
      Abstract: Parallel magnetic resonance imaging (pMRI) and compressed sensing (CS) have been recently used to accelerate data acquisition process in MRI. Matrix inversion (for rectangular matrices) is required to reconstruct images from the acquired under-sampled data in various pMRI algorithms (e.g., SENSE, GRAPPA) and CS. Singular value decomposition (SVD) provides a mechanism to accurately estimate pseudo-inverse of a rectangular matrix. This work proposes the use of Jacobi SVD algorithm to reconstruct MR images from the acquired under-sampled data both in pMRI and in CS. The use of Jacobi SVD algorithm is proposed in advance MRI reconstruction algorithms, including SENSE, GRAPPA, and low-rank matrix estimation in L + S model for matrix inversion and estimation of singular values. Experiments are performed on 1.5T human head MRI data and 3T cardiac perfusion MRI data for different acceleration factors. The reconstructed images are analyzed using artifact power and central line profiles. The results show that the Jacobi SVD algorithm successfully reconstructs the images in SENSE, GRAPPA, and L + S algorithms. The benefit of using Jacobi SVD algorithm for MRI image reconstruction is its suitability for parallel computation on GPUs, which may be a great help in reducing the image reconstruction time.
      PubDate: 2017-03-30
      DOI: 10.1007/s00723-017-0874-0
  • Examining Magnetic Models and Anisotropies in β -Cu 2 V 2 O 7 by
           High-Frequency ESR
    • Authors: M. Y. Ruan; Z. W. Ouyang; Y. C. Sun; Z. C. Xia; G. H. Rao; H. S. Chen
      Abstract: High-frequency electron spin resonance (ESR) measurements were carried out on a single crystal β-Cu2V2O7, where Cu–O edge-sharing chains are connected by non-magnetic VO4 tetrahedrons. Due to sizable anisotropies, analyses of bulk magnetic properties alone have not yielded any definite conclusion and the modeling of the magnetic lattice is controversial. By means of high-frequency ESR with operating frequencies of 135–405 GHz and at a temperature range of 4.2–50 K, the large g value anisotropy is determined, which removes the ambiguity of susceptibility fitting. Moreover, non-negligible exchange anisotropy is evaluated by analyzing high-field magnetization and antiferromagnetic resonance in antiferromagnetic state appearing below T N = 26 K. Based on these microscopic information, we found that alternating-chain model is the most reasonable candidate for explaining properties of the crystal. The present study shows the importance of combining macroscopic and microscopic probes in analyzing magnetic network of complex magnetic materials.
      PubDate: 2017-03-29
      DOI: 10.1007/s00723-017-0871-3
  • Studies of Nanosized Iron-Doped TiO 2 Photocatalysts by Spectroscopic
    • Authors: A. I. Kokorin; R. Amal; W. Y. Teoh; A. I. Kulak
      Abstract: Iron-doped TiO2 nanoparticles with iron content in the range of 0.005 < Fe/Ti < 0.3 were prepared using the flame spray pyrolysis method and investigated with CW X-band electron paramagnetic resonance (EPR), X-ray diffraction, and Fourier transform infrared spectroscopy. This allowed for the clarification of the internal organization of Fe–TiO2 nanoparticles. Different types of Fe(III) centers were distinguished in the samples: isolated high-spin paramagnetic Fe(III) ions (S = 5/2) in rhombic ligand fields state at 0.005 < Fe/Ti < 0.05, and Fe(III) ferromagnetic clusters at Fe/Ti < 0.1. All Fe-doped samples had rather high activity for the photocatalytic mineralization of oxalic acid under visible light illumination (λ > 400 nm) at 25 °C. Correlations were made between EPR and photocatalytic activity results. The specific surface area [S] data allowed us to deduce that the isolated Fe(III) centers were responsible for the photomineralisation of oxalic acid, while the Fe(III) ferromagnetic aggregates decreased the total efficiency of the system.
      PubDate: 2017-03-27
      DOI: 10.1007/s00723-017-0873-1
  • Comparison of the Effects of Different 19 F π Pulses on the Sensitivity
           and Phaseability of the 19 F- 13 C HSQC
    • Authors: Alexander A. Marchione; Breanna Conklin
      Abstract: The 19F-13C heteronuclear single quantum coherence (HSQC) experiment is vital for the structural elucidation of polyfluorinated organic species, yet its sensitivity and phaseability are limited by difficulties in uniform excitation of the widely disperse 19F spectral window. Adiabatic pulses of different types have previously been employed to generate effective π pulses for inversion and refocussing, but a systematic comparison of various adiabatic and other inversion pulses has not been published. In this work, it was observed that the use of a broadband inversion pulse (BIP) during the t 1 evolution period resulted in properly phaseable spectra for experiments optimized to detect 1 J CF, in contrast to CHIRP or WURST adiabatic pulses. For the INEPT and reverse-INEPT transfer segments of the HSQC, optimal sensitivity for resonances distant from the transmitter frequency was afforded by optimized universal rotation (BURBOP) or CHIRP pulses. In HSQC experiments with delays optimized for two-bond correlations, only the use of BURBOP pulses in INEPT and reverse-INEPT sequences afforded spectra cleanly phaseable across the F 2 and F 1 spectral windows. This observation is supported by off-resonance pulsed field gradient spin-echo experiments.
      PubDate: 2017-03-25
      DOI: 10.1007/s00723-017-0876-y
  • Force-detected ESR Measurements in a Terahertz Range up to 0.5 THz and
           Application to Hemin
    • Authors: Tsubasa Okamoto; Hideyuki Takahashi; Eiji Ohmichi; Hitoshi Ohta
      Abstract: We report a novel force-detected high-frequency electron spin resonance (HFESR) technique using a microcantilever in the terahertz region. In this technique, we attach a tiny sample on the microcantilever end and the ESR signal is detected as the cantilever bending. The bending is sensitively detected by fiber-optic Fabry–Perot interferometry. We applied this technique to a tiny amount (~16 ng) of metalloporphyrin, a model substance of hemoproteins, and successfully observed ESR signals at multiple frequencies up to 0.5 THz. This result indicates that the sample volume needed in multi-frequency HFESR can be greatly reduced by several orders of magnitude, and our novel technique would be a promising tool for HFESR studies of metalloproteins in the future.
      PubDate: 2017-03-24
      DOI: 10.1007/s00723-017-0872-2
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