996 resultados para 1995_07241306 CTD-31 4901001
Resumo:
Order parameter profiles extracted from the NMR spectra of model membranes are a valuable source of information about their structure and molecular motions. To al1alyze powder spectra the de-Pake-ing (numerical deconvolution) ~echnique can be used, but it assumes a random (spherical) dist.ribution of orientations in the sample. Multilamellar vesicles are known to deform and orient in the strong magnetic fields of NMR magnets, producing non-spherical orientation distributions. A recently developed technique for simultaneously extracting the anisotropies of the system as well as the orientation distributions is applied to the analysis of partially magnetically oriented 31p NMR spectra of phospholipids. A mixture of synthetic lipids, POPE and POPG, is analyzed to measure distortion of multilamellar vesicles in a magnetic field. In the analysis three models describing the shape of the distorted vesicles are examined. Ellipsoids of rotation with a semiaxis ratio of about 1.14 are found to provide a good approximation of the shape of the distorted vesicles. This is in reasonable agreement with published experimental work. All three models yield clearly non-spherical orientational distributions, as well as a precise measure of the anisotropy of the chemical shift. Noise in the experimental data prevented the analysis from concluding which of the three models is the best approximation. A discretization scheme for finding stability in the algorithm is outlined
Resumo:
The Military Monitor was a weekly periodical that was published every Monday. The first issue was printed for August 17, 1812 and is believed to have ceased in 1814, as the last issue located was April 2, 1814. The periodical was suspended with the November 23, 1812 issue and resumed with the December 14, 1812 issue. The quote at the top of the first page is "The public good our end". The periodical's various authors included: Desnoues, Joseph, 1794?-1837. O'Connor, Thomas, 1770-1855. Hardcastle, John, 1778?-1835. Van Pelt, Peter, 1779?-1843. Wall, Stephen. Van Riper, Nicholas. Other authors are believed to be the American Antiquarian Society. Proprietors: T. O'Connor and S. Wall, 1812; T. O'Connor, 1812- . Printers: Hardcastle and Van Pelt, for T. O'Connor and S. Wall, Sept. 14-Oct. 5, 1812; J. Desnoues, Oct. 12, 1812- ; N. Van Riper, Nov. 6, 1813- . This issue was included in a bound volume of the Military Monitor and American Register. Other Dates included are: 1812 October 12 1812 October 19 1812 November 23 1812 December 14 1812 December 21 1813 January 11 1813 February 1 1813 March 29 1813 April 5 1813 April 12 1813 April 26 1813 May 31
Resumo:
The Military Monitor was a weekly periodical that was published every Monday. The first issue was printed for August 17, 1812 and is believed to have ceased in 1814, as the last issue located was April 2, 1814. The periodical was suspended with the November 23, 1812 issue and resumed with the December 14, 1812 issue. The quote at the top of the first page is "The public good our end". The periodical's various authors included: Desnoues, Joseph, 1794?-1837. O'Connor, Thomas, 1770-1855. Hardcastle, John, 1778?-1835. Van Pelt, Peter, 1779?-1843. Wall, Stephen. Van Riper, Nicholas. Other authors are believed to be the American Antiquarian Society. Proprietors: T. O'Connor and S. Wall, 1812; T. O'Connor, 1812- . Printers: Hardcastle and Van Pelt, for T. O'Connor and S. Wall, Sept. 14-Oct. 5, 1812; J. Desnoues, Oct. 12, 1812- ; N. Van Riper, Nov. 6, 1813- . This issue was included in a bound volume of the Military Monitor and American Register. Other Dates included are: 1812 August 31 1812 October 12 1812 October 19 1812 November 23 1812 December 14 1812 December 21 1813 January 11 1813 February 1 1813 March 29 1813 April 5 1813 April 12 1813 April 26