压水堆中铬金属的产氢机理分析

为了从微观上寻找减少或控制氢气生成的措施,研究了压水堆核电站严重事故下金属铬和水反应生成氢气的微观机理,并计算了反应速率常数。铬水反应产氢的微观机理采用量子化学理论,应用量子化学软件包Gaussian03,在B3LYP/6-311++G(d,p)理论水平上进行研究。过渡态通过振动频率分析和最低能量路径计算确认,反应速率常数根据传统过渡态理论进行计算。计算结果表明,铬水反应是由两个基元反应Cr+H2O→CrOH+H和CrOH+H→CrO+H2组成的总包反应,其中基元反应CrOH+H→CrO+H2的正反应速率常数较小,该基元反应是铬水反应产氢的速控步。因此,在微观上减少或控制铬水反应产氢的措施应从基元反应CrOH+H→CrO+H2入手。     

Investigation of the interaction of amphetamine drug with Zn12O12 nanocage: a quantum chemical study

Journal of Computational Electronics - The interaction of amphetamine (AM) drug with a zinc oxide (Zn12O12) nanocage was studied based on the density functional theory (DFT) in a B3LYP/LANL2DZ...     

First-principle studies of the electronic structure and reflectivity of LaTiO3 and Sr doped LaTiO3 (La1-xSrxTiO3)

The electronic structures and optical properties of pure and Sr doped LaTiO₃ were studied using the first-principle density functional theory (DFT). The results show that the Fermi surface of LaTiO₃ lies in its conduction band, which makes its reflectivity (about 68.3% at the laser wavelength of 10.6 ??m) much higher than other ceramic materials. Sr doping lowers the conduction band and reduces the band gap of La_1-xSr_xTiO₃ which is beneficial to the prompt of reflectivity. We also found that shifting of the conduction band is not linear with Sr dopant concentration, and a minimum energy level is reached when x?=?0.25. For the reflectivity of La_1-xSr_xTiO₃, it first increases and then decreases with increasing Sr concentration; a maximum reflectivity (99.2%) is achieved when x?=?0.25.     

A first principles study of key electronic,optical, second and third order nonlinear optical properties of 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one: a novel D-$$\pi $$-A type chalcone derivative

In this work we assess the significant electrooptic properties of a novel chalcone derivative 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one using a computational approach. The ground-state molecular geometry was optimized, and geometrical parameters and vibrational modes are established and found to be in strong correlation with experimental results. The excitation energy is observed to be 326 nm (3.8 eV), calculated at the TD/B3LYP/6-31G level (stands for time dependent/Becke’s three Lee-Yang-Parr/basis set). Additionally, a unique insight was gained on a number of properties of the molecular levels such as the HOMO-LUMO gap (i.e. \({\sim } 4\,\hbox {eV}\)) and electrostatic potential maps. The potential applications of the 3-(4-chlorophenyl)-1-(pyridin-3-yl)prop-2-en-1-one (CPP) molecule in nonlinear optics are confirmed by second and third harmonic generation studies at five different characteristic wavelengths. The static and dynamic polarizability are found to be many-fold higher than that of urea. The second and third harmonic generation values of the titled molecule are found to be 56 and 158 times higher than standard urea molecule, respectively, computed at same wavelength (i.e. 1064.13 nm). From these studies it is clear that the material possesses superior properties and could be applied in optoelectronic device fabrications.     

Fabrication of 0.655Pb(Mg1/3Nb2/3)O3-0.345PbTiO3 functionally graded piezoelectric actuator by tape-casting

A 0.655Pb(Mg_1/3Nb_2/3)O₃-0.345PbTiO₃ (PMN-0.345PT) functionally graded (FG) piezoelectric actuator was fabricated by tape-casting. The effects of sintering temperature on the physical and electrical properties of the PMN-PT ceramics were initially investigated. High dielectric and piezoelectric properties of d ₃₃?=?700pC/N, k _p?=?0.61, ??_r?=?4.77?×?103, tan???=?0.014, P _r?=?30.68 ??C/cm² were obtained for the specimens sintered at 1200°C. Compared with the traditional solid-state reaction, the properties of the ceramics were significantly enhanced by tape-casting. The new FG piezoelectric actuator consisted of four layers, and the variation of changes in their d ₃₃ and ?? _r were graded opposite the thickness direction. The relationship between displacement and voltage for the actuator was also determined, with the results showing that it was linear. The driving displacement of the free end of the actuator reached 430.668 ??m.     

Electrical conductivities of strontium-doped rare earth ultraphosphates and oxyphosphates

Electrical conductivity of lanthanum ultraphosphate and neodymium oxyphosphate both doped with strontium, La_1-x Sr _x P₅O_14-?? (x?=?0, 0.01, 0.03 and 0.05 in nominal formulae) and (Nd_1-x Sr _x )₃PO_7-?? (x?=?0 and 0.03), respectively, was investigated with a two-probe ac technique. The electrical conductivity was measured as functions of oxygen partial pressure and water vapor pressure in the temperature range of 523 to 673?K for the former and 973 to 1273?K for the latter. La_1-x Sr _x P₅O_14-?? have considerable protonic conductivity, which was evidenced by isotope effect of hydrogen and deuteron on the electrical conductivity, over the wide range of oxygen partial pressure such as oxygen and hydrogen containing atmospheres. La_1-x Sr _x P₅O_14-?? exhibit protonic conductivities of 4.7?×?10^?5?2.2?×?10^?3?S?cm^?1 in the temperature range of 523?C673?K, which is comparable to the other phosphate based protonic conductors. Although protonic defects are considered to be induced and a major positive defect in (Nd_0.97Sr_0.03)₃PO_7-?? , attributed to small protonic mobility, (Nd_0.97Sr_0.03)₃PO_7-?? is a mixed oxide ion and electron hole conductor at 1173?C1273?K, then, it turns to be electron hole conductor below temperatures of 1073?K. (Nd_0.97Sr_0.03)₃PO_7-?? in 1.0?×?10^?2?atm oxygen?C1.9?×?10^?2?atm water vapor had smaller conductivity than that in unhumidified 1.0?×?10^?2?atm oxygen. The conductivities were 9.7?×?10^?3?3.1?×?10^?1?S?cm^?1 and 2.8?×?10^?3?2.5?×?10^?1?S?cm^?1 in the above gases, respectively, in the temperature range of 973?C1273?K. (Nd_0.97Sr_0.03)₃PO_7-?? had larger activation energy such as 165?kJ?mol^?1 than proton conducting La_1-x Sr _x P₅O_14-?? (76?kJ?mol^?1) including other proton conducting phosphates (68?C86?kJ?mol^?1).     

Towards a performance theory of robust adaptive control

We consider standard robust adaptive control designs based on the dead‐zone and projection modifications, and compare their performance w.r.t. a worst case transient cost functional penalizing the ??^∞ norm of the output, control and control derivative. If a bound on the ??^∞ norm of the disturbance is known, it is shown that the dead‐zone controller outperforms the projection controller if the a priori information on the uncertainty level is sufficiently conservative. The second result shows that the projection controller is superior to the dead‐zone controller when the a priori information on the disturbance level is sufficiently conservative. For conceptual clarity the results are presented on a non‐linear scalar system with a single uncertain parameter and generalizations are briefly discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Structural and thermoelastic study of the protonic conducting perovskite SrCe0.95Yb0.05O�� (��?��?3) between 373 K and 1273 K

The temperature dependence of the crystal structure of the protonic conducting perovskite SrCe_0.95Yb_0.05O_?? (??????3) has been determined from Rietveld refinement of neutron time-of-flight powder diffraction data in 25 K steps from 373 K to 1273 K. In contrast to most SrB^IVO₃ perovskites which show a sequence of structural phase transitions from Pmcn ?C Incn ?C I4/mcm - $ Pm\overline 3 m $ with increasing temperature, SrCe_0.95Yb_0.05O_?? remains orthorhombic with space group Pmcn from 4.2 K to the highest temperature measured. Crystallographic results are presented graphically in the form of the magnitude of the seven unique symmetry adapted basis vectors of a hypothetical aristotype perovskite phase. Thermoelastic properties of SrCe_0.95Yb_0.05O_?? deduced from the temperature variation of the unit cell volume and Debye-Waller factors are compared with literature values derived from independent calorimetric, Raman and elastic measurements. Thermodynamically, SrCe_0.95Yb_0.05O_?? behaves as a Debye-like solid with an average Grüneisen parameter in the range 1.4?C1.5, but with two characteristic temperatures, ??200 K and ??600 K, the lower temperature being more related to the cation vibrations, the higher to the anion vibrations.     

Interface and ionic interdiffusion in cofired dielectrics/ferrite layer composites

Zinc-magnesium titanate dielectrics/nickel-zinc-copper ferrite layer composites were prepared. An interlayer was designed to relax the interfacial stress because of the mismatch shrinkage between dielectric and ferrite. And as the results, zero camber and crack-free dielectric/interlayer/ferrite composite samples were obtained and the interface was continuous with no delamination. The cofiring interface and ionic interdiffusion between the constituents were investigated. The interdiffusion of the composite can be regarded as the semi-infinite diffusion-couple model and based on this diffusion model, the numerical simulation for the ionic composition distribution was carried out by computer, which was in agreement with the experimental results. The activation energies for the Ti⁴⁺, Ni²⁺, and Fe³⁺ were determined respectively. The difference between apparent activation energies was discussed in this article. The layer composite sintered at 930°C exhibited the dielectric properties: ?? _r ?=?18.2, tan???=?3.01?×?10^?3. Due to their low firing characteristics and realizable co-firing compatibility, the layer composites can serve as the promising medium materials in the multilayer LC filter.     

Optical signal inversion phenomena due to negative nonlinear absorption effect

A negative input-output characteristic was obtained in an erbium-doped yttrium aluminum garnet crystal which has multiple-level energy structure: absorption can occur between a ground level and an excited level (⁴I−⁴I) and between two other excited levels (⁴I−²H) in Er³⁺. It occurred at a wavelength between 786.6 and 788.4 nm by variation of the incident laser intensity in the intensity range of 60 nW/cm² to 100 W/cm². It is considered that an enhanced absorption occurs due to the excited-state absorption from ⁴I to ²H, its spectra matching the wavelength dependence of the incident laser In addition, optical signal inverter phenomenon was observed using a laser diode modulated at 10 MHz. By considering multiple excited-state absorption in detail, active functions such as an optical signal inverter could be derived from the negative nonlinear absorption effect. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(4): 74–80, 1997     

MR safety: simultaneous B 0, d��/dt, and dB/dt measurements on MR-workers up to 7 T

Object

The EU directive on safety requirements (2004/40/EC) limits the exposure to time varying magnetic fields to dB /dt = 200 mT/s. This action value is not clearly defined as it considers only the temporal change of the magnitude of ${\vec {B}}$ . Thus, only the translational motion in the magnet??s fringe field is considered and rotations are neglected.

Materials and methods

A magnetic field probe was constructed to simultaneously record the magnetic flux density ${\vec{B}}$ (x, y, z) with a 3-axis Hall sensor and the induced voltage due to movements with a set of three orthogonal coils. Voltages were converted into time-varying magnetic flux d ??(x, y, z)/dt serving as an exposition parameter for both translations and rotations. To separate the two types of motion, d B/dt was additionally calculated on the basis of the Hall sensor??s data. The calibrated probe was attached to the forehead of 8 healthcare workers and 17 MR physicists, and ${\vec {B}}$ and d??/dt were recorded during standard operating procedures at three different MR systems up to 7 T.

Results

The maximum percentage of the translational motion referring the data including both translations and rotations amounts to 32%. During volunteer measurements, maximum exposure values of d??/dt = 21 mWb/s, dB/dt = 1.40 T/s and ${\left| {\vec {B}}\right|= 2.75}$ Twere found.

Conclusion

The findings in this work indicate that both translations and rotations in the vicinity of an MR system should be taken into account, and that a single regulatory action level might not be sufficient.     

Numerical study of the thermoelectric power factor in ultra-thin Si nanowires

Low dimensional structures have demonstrated improved thermoelectric (TE) performance because of a drastic reduction in their thermal conductivity, ?? _l . This has been observed for a variety of materials, even for traditionally poor thermoelectrics such as silicon. Other than the reduction in ?? _l , further improvements in the TE figure of merit ZT could potentially originate from the thermoelectric power factor. In this work, we couple the ballistic (Landauer) and diffusive linearized Boltzmann electron transport theory to the atomistic sp³d⁵s*-spin-orbit-coupled tight-binding (TB) electronic structure model. We calculate the room temperature electrical conductivity, Seebeck coefficient, and power factor of narrow 1D Si nanowires (NWs). We describe the numerical formulation of coupling TB to those transport formalisms, the approximations involved, and explain the differences in the conclusions obtained from each model. We investigate the effects of cross section size, transport orientation and confinement orientation, and the influence of the different scattering mechanisms. We show that such methodology can provide robust results for structures including thousands of atoms in the simulation domain and extending to length scales beyond 10?nm, and point towards insightful design directions using the length scale and geometry as a design degree of freedom. We find that the effect of low dimensionality on the thermoelectric power factor of Si NWs can be observed at diameters below ??7?nm, and that quantum confinement and different transport orientations offer the possibility for power factor optimization.     

Back-to-Basics tutorial: X-ray diffraction of thin films

Electrocaloric (EC) refrigeration, is accepted as an auspicious method to develop eco-friendly cooling devices. Here, the investigations on the EC response and energy storage performance of heterovalent-doped Ba(Sn, Ti)O₃ relaxor ferroelectrics are carried out. Doping of aliovalent Mn or Nb elements into Ti site would regulate both the EC and energy storage behaviors. An enhanced EC temperature change up to 1.31 K, and a maximal recoverable energy storage density of 0.24 J cm^??3 with the efficiency as high as 87.11?%, can be observed under 70 kV cm^??1 in 0.5?% acceptor-doped Ba(Sn, Ti)O₃ ceramics. It is found that the local internal stress, the local charge fluctuation, and the oxygen deficiencies would benefit the electrical behaviors of this system. These results would shed light on the effect of the heterovalent substitution on the electrical properties of lead-free BaTiO₃ system and provide a novel and simple route to further improve the EC response and energy storage performance.

     

Preparation and characteristics of fine-grained ferroelectric glass-ceramic composites via a modified hybrid route at low temperature sintering

Dense, homogeneous and fully developed fine-grained ferroelectric Pb(Zr_0.53Ti_0.47)O₃?Cbased glass-ceramics have been successfully prepared at a low-sintering temperature of 850?C900°C by a modified hybrid process in air. The influence of the PbO-B₂O₃-SiO₂ (abbreviated as PBS) glass-gel content on the microstructure, dielectric, and ferroelectric properties of such glass-ceramics has been investigated. The temperature dependence of the dielectric constant indicated that the fine-grained Pb(Zr_0.53Ti_0.47)O₃ (abbreviated as PZT(53/47)) based glass-ceramic shows the characteristic dispersion at the Curie point. Ferroelectric hysteresis loop analyses have been performed to manifest the ferroelectric nature of the highly crystallized PZT(53/47) phase prepared by this modified novel hybrid process despite containing higher wt% glass-gel contents. The best dielectric and ferroelectric properties in a typical sample with 5% by weight of glass-gel content were found to have dielectric constant and loss tangent of 920 and 0.02 at 1 kHz, respectively. The saturation polarization (P _s ), and remanent polarization (P _r ) as well as the coercive field (E _c ) are 21.9 ??C/cm², 10.8 ??C/cm² and 2.19 kV/mm, respectively.     

Electrical properties of polylactic acid with nucleating agent added

We examined the electrical properties of polylactic acid (PLA) with a nucleating agent added. The PLA with added nucleating agent was then heat‐treated at 100 °C for 30 seconds. The crystallinity of the PLA with added nucleating agent increased to more than 40%, and its crystallization speed also increased significantly. The temperature dependence of the conductivity (σ) was investigated; at temperatures higher than 60 °C, σ of PLA to which the nucleating agent had been added showed a tendency to become lower than σ of PLA to which no nucleating agent had been added. The temperature dependence of the dielectric breakdown strength ( ) was investigated. of the PLA with added nucleating agent was about 5.0 MV/cm at 25 °C. Of particular note was the fact that the of PLA with added nucleating agent was about 4.7 MV/cm at 100 °C, which is about 3 times the value for PLA with no added nucleating agent. The temperature dependence of the relative dielectric constant (?_r^″) and the relative dielectric loss factor (?_r^″) was investigated. The peak dielectric absorption value of ?_r^″ for the PLA to which nucleating agent had been added showed a tendency to be lower than that of the PLA to which no nucleating agent had been added. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 25–31, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21293     

A density functional theory study of the structural,electronic, and optical properties of XGaO3 (X = V,Nb) perovskites for optoelectronic applications

An ab initio study using density functional theory (DFT) is carried out to explore the structural, electronic, and optical properties of vanadium gallate (VGaO₃) and niobium gallate (NbGaO₃). The structural properties of these compounds are determined by using the full-potential linearized augmented plane wave (FP-LAPW) technique as implemented in WIEN2k with a standard functional, i.e., the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA). In addition, the local density approximation plus Hubbard parameter (LDA?+?U) is employed to calculate the electronic bandgap and total and partial density of states (TDOS and PDOS), to overcome the limitation of the PBE-GGA functional in terms of underestimation of the electronic bandgap. The values computed for the indirect bandgap of VGaO₃ and NbGaO₃ are 0.45 and 0.51 eV, respectively, indicating that both materials are semiconductors in nature. The PDOS of the studied materials reveal that 3d-states of vanadium atoms, 4d-states of niobium atoms, and 2p-states of oxygen atoms form the valence band. Moreover, the Kramer–Kronig relations are used to compute the optical properties of the title compounds. The dielectric functions, refractive index, optical conductivity, absorption coefficient, extinction coefficient, energy loss function, and reflectivity of these materials are also computed. The results for the studied properties reveal that NbGaO₃ exhibits better properties than VGaO₃ for use in optoelectronic applications.

     

31P-NMR spectroscopy of human blood and serum: first results from volunteers and patients with congestive heart failure,diabetes mellitus and hyperlipidaemia

³¹P-containing metabolites in human blood, serum and erythrocytes were measured or calculated. Phosphodiesters were found in serum, but not in erythrocytes. 2,3-diphosphoglycerate and 2,3-diphosphoglycerate/ATP ratios were increased in patients with congestive heart failure (2,3-diphosphoglycerate by 13% in mild to moderate, 31% in severe congestive heart failure, 2,3-diphosphoglycerate/ATP ratio by 9% in mild to moderate, 38% in severe congestive heart failure); phosphodiesters were increased in diabetes mellitus (by 26%) and even more so in hyperlipidaemia (by 57%). Changes of blood³¹P compounds with disease states may have diagnostic potential and should be recognized for correction of organ spectra.     

Bemessungsregeln für Transformatoren

Übersicht Diese Arbeit behandelt nicht die Berechnung von Transformatoren im einzelnen, sondern die mathematische Formulierung allgemeiner Gesetzmäßigkeiten. Sie soll damit zum Verständnis der grundsätzlichen Zusammenhänge zwischen den maßgebenden Größen beitragen. Der erste Teil untersucht eine einfach berechenbare idealisierte Bauform, den Ringtransformator, ein zweiter Teil die gebräuchlichen Transformatortypen.

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Designing principles for transformersPart I: The ring-transformer

Contents The purpose of this paper is not to deal with individual transformer designs rather the mathematical formulation of universally applicable principles. It should thereby contribute to an understanding of the fundamental correlations between the important parameters. The first part treats an easily calculable idealized type, the ring-transformer, a second part the usual transformer-types.

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Verwendete Symbole B magnetische Flußdichte Induktion T=Vs/m² - b Fensterduchrmesser m - C zusammenfassende Konstante nachm ⁴ Gl. (3) - d Kernkreisdurchmesser des Eisen-m querschnitts - f Frequenz Hz=s^–1 - f _e Eisenfüllfaktor Hz=s^–1 - f _w Fensterfüllfaktor Hz=s^–1 - G Gewicht des aktiven Transformators; kgG=G _e +G _w - G _e Gewicht des Eisenkerns kg - G _w Gewicht der Wicklung kg - G ^* relatives Gewicht nach Gl. (12) kg - g _e Gewicht je m³ Eisenblech kg/m³ - g _w Gewicht je m³ Wicklungsdraht kg/m³ - I Stromstärke in der Ober-bzw. Unter-A spannungswicklung (Effektivwert) - J Stromdichte A/mm² - K Gesamtjahreskosten; DM/aK=K _p +K _ve +K _vw - K _p Jahreskosten für Verzinsung, Abschrei- DM/a bung, Instandhaltung, Steuern, Versicherung - K _ve Jahreskosten der Eisenverluste DM/a - K _vw Jahreskosten der Wicklungsverluste DM/a - K ^* relative Gesamtjahreskosten nach DM/a Gl. (32) - k _e Kosten einer kWh Eisenverluste ein- DM/kWh schließlich ihrer Abfuhr - k Kosten einer kWh Wicklungsverluste DM/kWh einschließlich ihrer Abfuhr - l _e Länge des Eisenkerns m - l Länge einer mittleren Windung m - P Preis des aktiven Transformators; DMP=P _e +P - P _e Preis des fertigen Eisenkerns DM - P Preis der fertigen Wicklung DM - P ^* relativer Preis nach Gl. (20) DM - p Jahresfaktor a^–1 - P _e Preis je kg Eisenblech+anteiliger DM/kg Zuschlag für nichtaktives Material des Kerns und dessen Zusammenbau - P Preis je kg Wicklungsdraht+anteiliger DM/kg Zuschlag für Isolierung, Abstützung und Zusammenbau der Wicklung - q _e blanker Eisenquerschnitt m² - q blanker Gesamtquerschnitt beider m² Wicklungen - S Scheinleistung des Transformators MVA - t _e jährliche Einschaltdauer h/a - t jährliche Beslastungsdauer mit Nenn-h/a leistung - U Ober- bzw. Unterspannung (Effektiv- V wert) - V Volumen des aktiven Transformators; m³ V=V _e +V - V _e Volumen des Eisenkerns m³ - V Volumen der Wicklung m³ - V ^* relative Volumen nach Gl. (8) m³ - v _e Eisenverlustleistung je kg Blech bei W/kg 1/T² B=1T - v Wicklungsverlustleistung je kg Leiter W/kg mm⁴/A² beiJ=1 A/mm² - Windungszahl der Ober-bzw. Unter-W/kg mm⁴/A² - _g Korrekturfaktor für das Gewicht W/kg mm⁴/A² - _k Korrekturfaktor für die Gesamtjahres-W/kg mm⁴/A² kosten - _p Korrekturfaktor für den Preis W/kg mm⁴/A² - Verhältnis zwischen den Jahreskosten W/kg mm⁴/A² der Verluste und den Jahreskosten für Verzinsung, Abschreibung usw.; =(K _ve +K _v )/K _p - 188-4 günstigstes Kostenverhältnis für W/kg mm⁴/A² die niedrigsten Gesamtjahreskosten - Verhältnis zwischen den Jahreskosten W/kg mm⁴/A² der Eisen- und der Wicklungsverluste; =K _ve /K _v - ₀ günstigstes Kosten verhältnis für die W/kg mm⁴/A² niedrigsten Gesamtjahreskosten - Preisverhältnis zwischen dem voll-W/kg mm⁴/A² ständigen Transformator und seinem aktiven Teil - magnetischer Fluß (Scheitelwert) Wb=Vs - Volumenverhältnis zwischen Eisenkern Wb=Vs und Wicklung; =V _e /V - ₀ günstigstes Volumenverhältnis für den Wb=Vs kleinsten Transformator - Gewichtsverhältnis zwischen Eisenkern und Wicklung; =G _e /G - ₀ günstigstes Gewichtsverhältnis für den Wb=Vs leichtesten Transformator - Preisverhältnis zwischen Eisenkern Wb=Vs und Wicklung; =P _e /P - ₀ günstigstes Preisverhältnis für die Ws=Vs billigsten Transformator - 0 _k günstigstes Preisverhältnis für die Ws=Vs niedrigsten Gesamtjahreskosten     

Double-tuned four-ring birdcage resonators forin vivo 31P-nuclear magnetic resonance spectroscopy at 11.75 T

A high signal-to-noise ratio (SNR) in³¹P-nuclear magnetic resonance (³¹P-NMR) spectroscopy can be obtained only with goodB ₀-field homogeneity and optimal coil sensitivity. This demands double-tumed coils with a highly sensitive³¹P channel and an additional¹H channel for¹H-magnetic resonance imaging, shimming,¹H decoupling, and nuclear Overhauser enhancement (NOE). For studies on an 11.75 T magnet, we built coils derived from the four-ring birdcage design originally described by Murphy-Boesch. A comparison with conventional, single-tuned coils shows that, in spite of double tuning, there is no significant loss in³¹P sensitivity while the¹H channel provides the requested performance. The coil design offers the advantage of circular polarization on both channels. Supported by the Deutsche Forschungsgemeinschaft (Ki 433/2-2 and Graduiertenkolleg Ha 1232/8-2).