Showing papers by "Zhong Chen published in 2001"
TL;DR: In this paper, the fracture properties of thin brittle films on compliant substrates for flexible optoelectronic devices were evaluated using experimental methods and their relevant analysis to evaluate fracture properties.
322 citations
TL;DR: In this article, a modified CRAZED pulse sequence was designed to investigate relative signal intensities with considerations of spin transverse relaxation, longitudinal relaxation, molecular diffusion, and optimal radio-frequency flip angles.
Abstract: Liquid nuclear magnetic resonance behaviors related to intermolecular dipolar interactions were investigated theoretically and experimentally in highly polarized two-component spin systems. A modified CRAZED pulse sequence was designed to investigate relative signal intensities with considerations of spin transverse relaxation, longitudinal relaxation, molecular diffusion, and optimal radio-frequency flip angles. The dissipation of the demagnetizing field due to relaxation and diffusion processes during the detection period was taken into account as well. For the first time, vigorous analytical expressions of the spin dynamics, including all the effects mentioned above, were derived from the combination of the demagnetizing field model and product operator formalism. In the regime where the linear approximation (γμ0M0t≪1) is valid, these explicit analytical expressions can quantitatively describe the signal behaviors related to intermolecular dipolar interactions. All the theoretical predictions based on ...
47 citations
TL;DR: In this paper, an analytical expression for the dependence of signal intensities on RF pulse flip angles was derived for the cases when higher-order expansion terms of Bessel functions can be neglected from a combination of dipolar demagnetizing field treatment and product operator formalism.
28 citations
Patent•
20 Mar 2001TL;DR: In this article, a group of pulse sequences are used in which, (a) the standard β=π/2 pulse in the original CRAZED sequence is replaced with a π/3 pulse.
Abstract: In nuclear magnetic resonance imaging of the human brain or the like, multiple quantum coherences, such as intermolecular double quantum coherence (iDQC) between water molecules, are used for soft tissue contrast. A group of pulse sequences are used in which, (a) The standard β=π/2 pulse in the original CRAZED sequence is replaced with a π/3 pulse. The maximum signal derived from iDQCs is increased by a factor of 3{square root over (3)}/4. (b) The position of the acquisition window is adjusted, and a large acquisition window (small bandwidth) is used to sample a broad range of time-domain signals. (c) Receiver dynamic range is optimized. (d) A two-step phase cycle scheme for iDQC-encode gradients is designed to remove additional undesired coherence pathways.
21 citations
Patent•
20 Mar 2001
TL;DR: In this paper, a group of pulse sequences are used in which, (a) the standard β=π/2 pulse in the original CRAZED sequence is replaced with a π/3 pulse.
Abstract: In nuclear magnetic resonance imaging of the human brain or the like, multiple quantum coherences, such as intermolecular double quantum coherence (iDQC) between water molecules, are used for soft tissue contrast. A group of pulse sequences are used in which, (a) The standard β=π/2 pulse in the original CRAZED sequence is replaced with a π/3 pulse. The maximum signal derived from iDQCs is increased by a factor of 3{square root}{square root over (3)}/4. (b) The position of the acquisition window is adjusted, and a large acquisition window (small bandwidth) is used to sample a broad range of time-domain signals. (c) Receiver dynamic range is optimized. (d) A two-step phase cycle scheme for iDQC-encode gradients is designed to remove additional undesired coherence pathways.
3 citations