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171.
A low-field nuclear magnetic resonance spectrometer for non-invasive monitoring of human finger blood glucose fluctuations was developed. Saline solution and blood serum samples with different glucose concentrations were first detected by the spectrometer and it has been found that there was a high-linear correlation between the glucose concentration and the transverse relaxation time. Then, the spectrometer was employed to noninvasively measure a finger from each of the several volunteers. The experiment results showed that the transverse relaxation time of the human finger increases with human blood glucose concentration. In conclusion, the human finger nuclear magnetic resonance spectrometer could be a potential tool to noninvasive monitoring of human body’s blood glucose fluctuations in the future. 相似文献
172.
对有机高分子磁体的分子设计研究进行了综述,讨论了设计有机高分子磁体主要的4种理论模型,即Heiter London自旋交换模型、分子间电子转移模型、高自旋多重度模型和超级交换模型,并对这一领域的发展和应用进行了展望. 相似文献
173.
研究了直接转矩控制原理,以TMS320LF2407ADSP为核心设计了永磁同步电机控制系统,给出了硬件结构及软件流程,实验证明了系统设计的正确性。 相似文献
174.
Uta Albold Heiko Bamberger Philipp P. Hallmen Joris vanSlageren Biprajit Sarkar 《Angewandte Chemie (International ed. in English)》2019,58(29):9802-9806
The energy barrier leading to magnetic bistability in molecular clusters is determined by the magnetic anisotropy of the cluster constituents. By incorporating a highly anisotropic four‐coordinate cobalt(II) building block into a strongly coupled fully air‐ and moisture‐stable three‐spin system, it proved possible to suppress under‐barrier Raman processes leading to 350‐fold increase of magnetization relaxation time and pronounced hysteresis. Relaxation times of up to 9 hours at low temperatures were found. 相似文献
175.
ZHANG Shu-Qun CHEN Zhi-De 《理论物理通讯》2008,50(7):248-252
Spin parity effect on magnetic relaxation by quantum tunneling in the biaxial spin model is studied by taking into account the transverse local stray field. It is shown that the square root time dependence in the even resonance occurs in the presence of a distribution of transverse anisotropic parameters, while the odd resonance always shows exponential relaxation. Magnetic relaxation under a sweeping field is also studied. The variation of the relaxation curve with the increasing distribution width of the local stray field for even resonance is qualitatively different from that of the odd resonance. The theoretical result on even resonance is in agreement with experimental results on Fe8 system, while the prediction for odd resonance awaits the experimental verification. 相似文献
176.
This paper presents the analytical and simulation responses of the closed orbit distortion in the SSRF storage ring to random and plane wave like magnet vibrations respectively. It is shown that the use of girder is very beneficial in the view of suppressing this response function. Effect of the independently supported gradient bending magnets to the closed orbit response is given. An analytic formula is written to give a rough estimate of the closed orbit distortion due to ground motion, taking into account the closed orbit response function and girder transfer function. As an example, the result of SSRF case is given. 相似文献
177.
T. Idehara T. Saito H. Mori H. Tsuchiya La Agusu S. Mitsudo 《International Journal of Infrared and Millimeter Waves》2008,29(2):131-141
Long pulse operation up to 1 msec of a high frequency gyrotron with a pulse magnet has been successfully carried out in a
frequency range including 1 THz. In the experiments, the timing of an electron beam pulse injection is adjusted at the top
of the magnetic field pulse, where the variation of field intensity is negligible. The operation cavity modes seem to be TE1, 12 and TE4,12 at the second harmonics. The corresponding frequencies are 903 GHz and 1,013 GHz, respectively. Additionally several features
of radiation measurement results of the gyrotron are described and brief considerations are presented. 相似文献
178.
Rapidly solidified nanocomposite Nd9Fe77−xB14Tix alloys, consisting of magnetic Nd2Fe14B phase and soft magnetic phases, were investigated. The effect of titanium addition on the structure and magnetic properties was studied. It was found that 2–4 at% Ti addition leads to substantial increase of the coercivity and maximum energy product, maintaining the remanence unchanged. The highest properties: Jr=0.81 T, JHc=907 kA/m, (BH)max=99 kJ/m3, were achieved for the Nd9Fe73B14Ti4 alloy. This effect we attribute to the formation of fine and homogeneous grain structure and a change of the phase morphology in the Ti-containing alloys. The initial magnetization curve indicates a change of the coercivity mechanisms giving rise to pinning of domain walls, which is caused by reduction of the crystallite size. 相似文献
179.
J.T. Elizalde-Galindo J.L. Hidalgo C.E. Botez J.A. Matutes-Aquino 《Journal of magnetism and magnetic materials》2008,320(14):e222-e225
Nanocrystalline Sm0.5Y0.5Co5 powders with high coercivity HC and enhanced remanence Mr were prepared by mechanical milling and subsequent annealing. Annealing temperatures T ranging from 973 to 1173 K, and times t ranging from 1 to 5 min were used. X-ray diffraction (XRD) and DC-magnetization measurements were carried out to study the microstructure and magnetic properties of these samples. XRD patterns demonstrate that the average grain size D of the nanocrystalline powders depends on the annealing temperature T and time t: D ranges from 11 nm (for T=973 K and t=1 min) to 93 nm (for T=1173 K and t=5 min). Magnetic measurements performed at room temperature indicate high coercivity values (HC>955 kA/m), and enhanced remanence (Mr/Mmax>0.5) for all samples. A strong annealing-induced grain size dependence of these magnetic properties was found. 相似文献
180.
J.T. Elizalde-Galindo F.J. Rivera Gmez J.A. Matutes-Aquino C.E. Botez 《Journal of magnetism and magnetic materials》2008,320(14):e58-e60
Nanostructured YCo5 (70%wt)+Y2Co17 (30%wt) composite powders were prepared by mechanical milling and subsequent annealing at 1073 K for 1.5 min. The average grain size D of the YCo5 and Y2Co17 phases, obtained from XRD data, was 14 and 12 nm, respectively. The temperature dependence of the magnetic properties was studied by DC magnetization measurements at temperatures T ranging from 3 to 300 K. Hysteresis loops (Hmax=70 kOe) show that both the coercivity HC and the squareness σr/σmax are temperature-dependent. The coercivity increases from 12 kOe at room temperature to 18 kOe at T=3 K. The observed enhanced remanence (σr/σmax>0.5) indicates that a strong exchange coupling is present at all temperatures used in this study. The maximum magnetization σmax changes little with temperature and has a value of about 70% of the effective saturation magnetization of the title compound. 相似文献