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31.
A computerized plotting method for the determination of the stoichiometry of complexes is introduced. The method has no assumptions or simplifications, and is applicable to both strong and weak complexes. Different stoichiometries, as a function of the metal to ligand concentration-ratio, can be identified in a single diagram. Furthermore, non-stoichiometric complexes can be recognized. 相似文献
32.
Michael condensation of the dienone (3) with the vinyllactone (19) leads to the compound (20). Attempts to construct the B ring of the taxane skeleton by direct cyclization of (20) are reported . The stereochemistry of (20) is established by X-ray structure determination. 相似文献
33.
Mechanics of deformation-triggered pattern transformations and superelastic behavior in periodic elastomeric structures 总被引:1,自引:1,他引:0
K. Bertoldi M.C. Boyce S. Deschanel S.M. Prange T. Mullin 《Journal of the mechanics and physics of solids》2008,56(8):2642-2668
Recently, novel and uniform deformation-induced pattern transformations have been found in periodic elastomeric cellular solids upon reaching a critical value of applied load [Mullin, T., Deschanel, S., Bertoldi, K., Boyce, M.C., 2007. Pattern transformation triggered by deformation. Phys. Rev. Lett. 99, 084301; Boyce, M.C., Prange, S.M., Bertoldi, K., Deschanel, S., Mullin, T., 2008. Mechanics of periodic elastomeric structures. In: Boukamel, Laiarinandrasana, Meo, Verron (Eds.), Constitutive Models for Rubber, vol. V. Taylor & Francis Group, London, pp. 3–7]. Here, the mechanics of the deformation behavior of several periodically patterned two-dimensional elastomeric sheets are investigated experimentally and through numerical simulation. Square and oblique lattices of circular voids and rectangular lattices of elliptical voids are studied. The numerical results clearly show the mechanism of the pattern switch for each microstructure to be a form of local elastic instability, giving reversible and repeatable transformation events as confirmed by experiments. Post-deformation transformation is observed to accentuate the new pattern and is found to be elastic and to occur at nearly constant stress, resulting in a superelastic behavior. The deformation-induced transformations have been physically realized on structures constructed at the millimeter length scale. This behavior should also persist at the micro and nano length scales, providing opportunities for transformative photonic and phononic crystals which can switch in a controlled manner and also exploiting the phenomenon to imprint complex patterns. 相似文献
34.
The use of ultrasonic sensors for process control is currently widespread for flow, level or distance measurements. Recently, interest has increased, too in the application of ultrasonic sensors to concentration measurements in complex liquids. In this application there are high demands for a defined and stable quality of the properties of both the sensor transfer function and the sound field characteristic. For a detailed investigation and characterization of ultrasonic sensor propertiess, an efficient PC-controlled measuring system was developed by the Institut fur Automation und Kommunikation (IFAK). In this contribution, this high performance approach is presented to make visible the vibrating ultrasonic sensor surface as well as the sound field in front of acoustic sensors in liquids. 相似文献
35.
Dr. Heinz Prange 《Zeitschrift für Physik A Hadrons and Nuclei》1968,212(5):415-434
Using the Mössbauer technique electric hyperfine interactions of the first excited non-rotational states at 64 keV in157Gd and at 86.5 keV in155Gd have been determined in GdF3 and GdCl3· 6H2O. For the ratio of quadrupolmoments the ratiosQ 64 157 /Q g 157 =1.74±0.04,Q 86.5 155 /Q g 157 =?0.07 ± 0.21 andQ g 155 /Q g 157 =0.78 ± 0.06 were found. In addition isomer shifts were observed from which a ratio δ〈r2〉 64 157 /δ〈r2〉 86.5 155 =?2.6±0.15 can be inferred. 相似文献
36.
37.
Quantum Zeno and anti-Zeno paradoxes 总被引:1,自引:0,他引:1
Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox).
We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure
change of state: an anti-Zeno paradox. 相似文献
38.
A general framework is considered for treating quantum corrections to the classical limit in the Wigner function formalism. We discuss the quantal effect on the classical phenomena such as period doubling and the breakup of KAM tori. By using an exact renormalization group method, the scaling factor for Planck's constant is derived as an eigenvalue of the linearized renormalization transformation. 相似文献
39.
粉粒体两相流的电容层析成象测量 总被引:4,自引:0,他引:4
粉粒体系统中的固相浓度分布的在线测量是十分困难的问题.电容层析成象技术是一种近年来发展起来的非侵入式快速浓度场测量技术.它不干扰流场,不受流动中颗粒浓度、加速度、不透明等因素的制约.本文讨论其测量原理、应用、近期进展、存在的主要问题及其解决的对策. 相似文献
40.
ac Conductivity measurements are carried out across the metal to insulator transition in NiAl0.7Cr0.7Fe0.6O4. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling
behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency
conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime. 相似文献