Delay Optimization

An n,l-ADEQUATE spectrum of strychnine (1) recorded using a /CH delay optimized for 8 Hz and a 1JCC delay optimized for 50 Hz is shown in Figure 11.77 The spectrum was recorded with the F1 frequency range set for 350 ppm with the transmitter located at 175 ppm just downfield of the CIO carbonyl resonance. To illustrate the interpretation of an n, 1-ADEQUATE spectrum, correlations for the C14 methine resonance will be considered. Obviously, based on the structure of strychnine (1), there are three carbon-carbon correlations possible from C14 to the C13 methine, the C15 methylene, and C21 quaternary vinyl carbons. 

FIGURE 29. 29Si—2 Si 2D INADEQUATE spectrum of (SigOigtin-C H-jgC-ClC ,1U,)2- I ( , Si 0-0 n-Pr , 3-CIC3H6), in CDCI3 solution (59.60 MHz, delays optimized for J = 0.7 Hz, relaxation delay 20 s). Reprinted from Reference 226. Copyright 1994, with permission from Elsevier Science... 

The impact of delay optimization versus long-range correlation response intensity is graphically illustrated by the data presented in Figure 14.1, which were derived for... 

Zn and Ca in many biologically important molecules and can further be detected by NMR, Cd was selected for the study. chemical shift data for several analogues and their respective Cd complexes are reported in Table 32. The HMBC data used in this study were acquired with a long-range delay optimization of 50 ms (10 Hz). 

Kerlan JE, Sawhney NS, Waggoner AD, et al. Prospective comparison of echocardiographic atrioventricular delay optimization methods for cardiac resynchronization therapy. Heart Rhythm 2003 3 148-54. 

Morales M-A, Startari U, Panchetti L, Rossi A, Piacenti M. Atrioventricular delay optimization by doppler-derived left ventricular dP/dt improves 6-month outcome of resynchronized patients. PACE 2006 29 564-8. 

Chan P. K. et al Delay optimization of carry-skip adders and block carry-lookahead adders. In Proc. 10th Computer Arithmetic Symp., Grenoble, S. 154-164, June 1991. 

C CP-MAS NMR No sample preparation Relaxation delay optimized. DA is calculated from the relative areas of CH3 to the total resonances [214, 216]... 

Figure 3.10 (A) MAS-NMR spectrum of the p-L-Asp-L-Ala dipeptide at 20 T 850 MHz) and vr = 63I

DH -INADEQUATE is also illustrated in Fig. 3.1 OB, where the DQ/SQ correlation spectrum of the (l-L-Asp-L-Ala dipeptide has been recorded at = 63 kHz and 850 MHz. The DQ excitation delay optimized for the DQ intensity is around 500 ps however, using short delays for the creation of DQ coherences usually leads to distorted peaks (as seen in the simulation from Ref. [130]), and correlation peaks for distant spins may not be observed. Therefore, using longer delays (around 1 ms) leads to reduced peak intensities, but the spectra usually present more peaks, corresponding to pairs of spins separated by larger distances and less distorted peaks. 

Chang K-H, Markov IL, Bertacco V (2007) Safe delay optimization for physical synthesis. ASP-DAC 2007 628-633... 

Moffitt MD et al (2008) Path smoothing via discrete optimization. DAC 2008, pp 724-727 Kannan LN, Suaris PR, Pang H-G (1994) A methodology and algorithms for post-placement delay optimization. DAC 1994, pp 327-332... 

Fig. 10.12 (A) Same patient as Fig. 10.11. Pulmonary capillary wedge pressure shows large cannon waves. Scale 0-40mmHg. (B) Same patient after testing with a temporary dual chamber pacemaker with a physiologic AV delay. Note the normal pulmonary capillary wedge pressure. The patient was markedly improved after the implantation of a dual chamber pacemaker with AV delay optimization. (Barold SS. Acquired Atrioventricular Block. In Kusumoto F, Goldschlager N (Eds), Cardiac Pacing for the Clinician, Philadelphia, PA Lippincott, Williams Wilkins, 2001 with permission).

Porciani MC, Dondina C, Macioce R, Demarchi G, PieragnoU P, MusUli N, ColeUa A, Ricciardi G, Michelucci A, Padeletti L. Echocardiographic examination of atrioventricular and interventricular delay optimization in cardiac resynchronization therapy. Am J Cardiol 2005 95 1108-10. 

Porterfield. Device based intracardiac delay optimization vs. echo in ICD patients (acute lEGM AV/PV and VV study).(abstract). Europace 2006 8 (Supplement 1). 

Schorn et al. [22] used the standard HMQC pulse sequence with delays optimized for to provide the needed two-bond C—F correlations used to assign the resonances in a bis(n-perfluoroalkyl)zinc complexes. To be able to distinguish correlations due to leakage from J p correlations in the / f experiment, no decoupling was applied during the acquisition period. Cross-peaks from 7cf correlations were easily identified from their large doublet splitting in the F chemical shift dimension. 

Figure IOC shows that the simulated F2-coupled perfect-HSQC spectrum without the CLIP pulse stiU shows some phase distortions provided A does not match the corresponding J(CH) value. For instance, deviations of 10 and 20 Hz between J(CH) and the A delay optimization generate antiphase contributions of about 11% and 23%, respectively, in a 140-Hz optimized experiment. Such distortions can be efficiently suppressed using the perfect-CLIP-HSQC pulse scheme (Fig. 8B), affording perfect pure IP multiplet patterns for all peaks independent of their J(HH) and J(CH) values (Fig. lOD).

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