G-BIRD

Key Words NMR, Heteronuclear Long-range correlation, HMBC, CT-HMBC, ACCORD-HMBC, IMPEACH-MBC, BIRD-HMBC, G-BIRD-HMBC, CIGAR-HMBC, IMPACT-HMBC, TS-HMBC, Broadband-HMBC, H2BC, edited HMBC, 10-ppm HMBC, /CH artefacts suppression, Spectral editing... 

The limits of the original BIRD-FIMBC sequence and the excellent /ci 1 filter quality of the double tuned G-BIRD element is exemplified in the spectra obtained with the molecule 1,3-butadiynyl (ferf-butyl) diphenyl-silane (Figure 6). This molecule provides a stringent test, since it contains all together aliphatic, aromatic and acetylenic protons, and the corresponding ch coupling constant values vary from 125 to 260 Flz. 

Figure 12 Comparison of Vch artefacts intensity illustrated with ID rows taken from a BIRD-HMBC (A), (D) and (G) a G-BIRD-HMBC (B), (E) and (H) and a double tuned G-BIRD-HMBC (C), (F) and (I) experiments showing the Vch artefacts and nJCH responses of C-6 at 135.6 ppm (A), (B) and (C), C-l at 67.2 ppm (D), (E) and (F) and C-10 at 27 ppm (G), (H) and (I) of the 1,3-butadiynyl (tert-butyl) diphenylsilane molecule dissolved in CDCl3. For the BIRD-HMBC and G-BIRD-HMBC experiments, the delays S were adjusted to aV-value of 190 Hz, as an average value for the extreme range of coupling constants for this molecule (125-260 Hz). For the double tuned G-BIRD-HMBC, the /ch nnax and /ch nnin values were set to 240 and 145 Hz, respectively. The corresponding values for the S and S delays were 3.13 and 2.17 ms, adjusted toj values of 160 and 230 Hz, respectively. For both G-BIRD-HMBC experiments, 192 is BIP 720-100-10 pulses have been used for 13C inversion. The same vertical scale is used for all spectra. Residual /ch signals are denoted with arrows.

BAF defined as the ratio of the test chemical concentration in (a part of) an organism (e.g., bird, mammal or fish) to the concentration in its food (e.g., laboratory fodder, plants, invertebrates, birds, mammals) at steady state. BAFs are generally used for accumulation by birds, mammals and fish and are expressed on a weight basis. 

Lewis, D. F. V., Lake, B. G., Bird, M. G., Loizou, G. D., Dickins, M., and Goldfarb, P. S. (2003) Homology modelling of human CYP2E1 based on the CYP2C5 crystal structure Investigation of enzyme-substrate and enzyme-inhibitor interactions. Toxicol, in Vitro 17, 93-105. 

Examples of risk hypotheses given by USEPA (1998) are textual (e.g., birds die when they consume recently applied granulated carbofuran ). Eor a quantitative risk assessment it will be preferable to express risk hypotheses using formal mathematical equations. 

Jensen, P., Rubo-Stipec, M., Canino, G., Bird, H., Dulcan, M.K., Schwab-Stone, M., and Lahey, B. (1999) Parent and child contributions to diagnosis of mental disorder are both informants always necessary / Am Acad Child Adolesc Psychiatry 38 1569-1579. 

M.G. Bird, 2835 Mill Road, Doylestown, PA 18901, United States... 

The following discussion is excerpted from Mullin (1993) and Elwell and Scheel (1975). Diffusional boundary theory is well-established (see e.g., Bird et al., 1960) and the concept of a boundary unstirred layer was introduced a century ago. Noyes and Whitney (1897) proposed that the change in the rate of crystal growth (dm/dt) was controlled by diffusion from the bulk concentration to the crystal (equilibrium) interface. 

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