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951.
952.
953.
Summary The pH versus fluorescence intensity profiles of a series of new pH-indicators are reported. They are characterized by two pKa-values in the 3.7–4.9 and 6.9–7.9 range, respectively. The strong change in fluorescence intensity with pH allows the determination of pH's over a much wider range (typically 2–9) than with one-step indicators. They are therefore considered to be of potential utility for measurement of pH over the neutral and slightly acidity range which occurs, for instance, in bioliquids such as urine.
Eine neue Gruppe fluorescierender pH-Indicatoren für einen erweiterten pH-Bereich
Zusammenfassung Die Fluorescenzintensitätsprofile als Funktion des pH-Wertes einer Reihe von neuen pH-Indicatoren werden untersucht. Sie sind charakterisiert durch zwei pKa-Werte im Bereich 3,7–4,9 bzw. 6,9–7,9. Die gefundene starke Änderung der Fluorescenzintensität mit dem pH-Wert erlaubt eine pH-Bestimmung über einen viel weiteren Bereich (typischerweise 2 – 9) als mit einstufigen Indicatoren. Aus diesem Grund werden sie als potentiell nützlich angesehen zur Messung von pH-Werten im neutralen und schwach sauren Bereich, wie er z.B. in biologischen Flüssigkeiten, etwa im Urin, gegeben ist.相似文献
954.
955.
Stability of tokamak plasmas with internal transport barriers against high n ideal magnetohydrodynamic ballooning mode
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A ballooning mode equation for tokamak plasma, with the toroidicity and the Shafranov shift effects included, is derived for a shift circular flux tokamak configuration. Using this equation, the stability of the plasma configuration with an internal transport barrier (ITB) against the high n (the toroidal mode number) ideal magnetohydrodynamic (MHD) ballooning mode is analysed. It is shown that both the toroidicity and the Shaftanov shift effects are stabilizing. In the ITB region, these effects give rise to a low shear stable channel between the first and the second stability regions. Out of the ITB region towards the plasma edge, the stabilizing effect of the Shaftanov shift causes the unstable zone to be significantly narrowed. 相似文献
956.
采用射频磁控溅射技术在Pt/Ti/SiO2/Si(100)衬底上生长了掺镧钛酸铅(PLT)铁电薄膜.用X射线衍射技术(XRD)研究了PLT薄膜结晶性能,结果表明PLT薄膜为(111)择优取向钙钛矿相织构.使用原子力显微镜(AFM)和压电响应力显微镜(PFM)分别观察了PLT薄膜的表面形貌和对应区域的电畴结构.PFM观察显示PLT薄膜中存在90°纳米带状畴,电畴的极化为首尾相接的低能量的排列方式,带状畴的宽度为20-60nm.研究了PLT10铁电薄膜的制备条件与性能之间的关系.发现在优化条件下制备的PLT10铁电薄膜的介电常数εr为365、介电损耗tgδ为0.02,热释电系数γ为2.18×10-8C·(cm2·K)-1,可以满足制备非制冷红外探测器的需要. 相似文献
957.
Features of the total disintegration events of heavyemulsion targets caused by 4.5A GeV/c16O
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Total disintegration events produced by 4.5\,A GeV/c $^{16}$O--AgBr interactions are
analysed to investigate the characteristics of secondary charged particles produced
in such collisions. The multiplicity distributions of grey, black, and relativistic
charged particles can be well represented by Gaussian distribution. The average
multiplicity of grey particles is found to increase with the mass of projectile
increasing, while that of black particles is found to decrease with the mass of
projectile increasing. This result is in good agreement with the prediction of
fireball model. Finally, the linear dependence between grey and black particles is
observed, but there is no distinct dependence between the production of relativistic
charged particles and the target excitation. 相似文献
958.
959.
THE FIRST EXPERIMENT OF A THz GYROTRON WITH A PULSE MAGNET 总被引:1,自引:0,他引:1
T. Idehara H. Tsuchiya O. Watanabe La Agusu S. Mitsudo 《International Journal of Infrared and Millimeter Waves》2006,27(3):319-331
A THz gyrotron with a pulse magnet has been designed, constructed and operated in FIR FU. It is developed as one of high frequency
gyrotrons included in Gyrotron FU Series. The gyrotron has already achieved the first experimental result for high frequency
operations whose radiation frequency exceeds 1 THz. In this paper, the design detail and the operation test results for sub-terahertz
to terahertz range are described. The second harmonic operation is confirmed experimentally at the expected frequency of 1.005
THz due to TE6,11 cavity mode at the magnetic field intensity of 19.0 T. 相似文献
960.
R. Lü H. Pan J.-L. Zhu B.-L. Gu 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):479-491
The tunneling of a giant spin at excited levels is studied theoretically in mesoscopic magnets with a magnetic field at an
arbitrary angle in the easy plane. Different structures of the tunneling barriers can be generated by the magnetocrystalline
anisotropy, the magnitude and the orientation of the field. By calculating the nonvacuum instanton solution explicitly, we
obtain the tunnel splittings and the tunneling rates for different angle ranges of the external magnetic field ( θ
H = π/2 and π/2 < θ
H < π). The temperature dependences of the decay rates are clearly shown for each case. It is found that the tunneling rate
and the crossover temperature depend on the orientation of the external magnetic field. This feature can be tested with the
use of existing experimental techniques.
Received 12 March 2001 and Received in final form 18 October 2001 相似文献