Browsing by Author "Cheng, TH"

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Physicochemical characterization of the dimeric lanthanide complexes [en{Ln(DO3A)(H2O)}(2)] and [pi{Ln(DTTA)(H2O)}(2)](2-): a variable-temperature O-17 NMR study
(2004-03-01)
Lee, TM
;
Cheng, TH
;
Ou, MH
;
Chang, CA
;
Liu, GC
The Gd(III) complexes of the two dimeric ligands [en(DO3A)(2)] {N,N'-bis[1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-10-yl-methylcarbonyl]-N,N'-ethylenediamine] and [pi(DTTA)(2)](8-) [bisdiethylenetriaminepentaacetic acid (tratis-1,2-cyclohexanediamine)] were synthesized and characterized. The O-17 NMR chemical shift of H2O induced by [en(Dy(DO3A)}(2)] and [pi{Dy(DTTA)}(2)](2-) at pH 6.80 proved the presence of 2.1 and 2.2 inner-sphere water molecules, respectively. Water proton spin-lattice relaxation rates for [en(Gd(DO3A)(H2O)}(2)] and [pi(Gd(DTTA)(H2O)}(2)](2-) at 37.0 +/- 0.1degreesC and 20 MHz are 3.60 +/- 0.05 and 5.25 +/- 0.05 mm(-1) s(-1) per Gd, respectively. The EPR transverse electronic relaxation rate and O-17 NMR transverse relaxation time for the exchange lifetime of the coordinated H2O molecule and the H-2 NMR longitudinal relaxation rate of the deuterated diamagnetic lanthanum complex for the rotational correlation time were thoroughly investigated, and the results were compared with those reported previously for other lanthanide(III) complexes. The exchange lifetimes for [en(Gd(DO3A)(H2O)}(2)] (769 +/- 10 ns) and [pi[Gd(DTTA)(H2O)}(2)](2-) (910 +/- 10 ns) are significantly higher than those of [Gd(DOTA)(H2O)](-) (243 ns) and [Gd(DTPA)(H2O)](2-) (303 ns) complexes. The rotational correlation times for [en{Gd(DO3A)(H2O)}(2)] (150 +/- 11 ps) and [pi[Gd(DTTA)(H2O)}(2)](2-) (130 +/- 12 ps) are slightly greater than those of [Gd(DOTA)(H2O)](-) (77 ps) and [Gd(DTPA)(H2O)](2-) (58 ps) complexes. The marked increase in relaxivity (r(1)) of [en{Gd(DO3A)(H2O)}(2)] and [pi{Gd(DTTA)(H2O)(2)](2-) result mainly from their longer rotational correlation time and higher molecular weight. Copyright (C) 2004 John Wiley Sons, Ltd.
Study in IC chip failure during pick-up process by using experimental and finite element methods
(2006-03-10)
Cheng, TH
;
Du, CC
;
Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
Stress contours of an IC chip and the displacement contours of the adhesive between an IC chip and blue tape in the pick-up integrated circuit (IC) chip process are obtained using experimental and finite element methods. The physical and mechanical properties of the material used in FEM are determined by pre-experimental tests. Some factors that importantly influence the failure of a pick-up IC chip during the pick-up IC chip process are proposed. The pre-expermiental material properties are manifest in the practical behavior of material, so the post-experimental results are approximately consistent with the FEM results. Post-expermients further demonstrated that the findings of this study can be used to increase the success rate of the pick-up IC chip process. (c) 2005 Elsevier B.V. All rights reserved.