__contents of SHEET#2__

Sheet 1. Title page with an abstract

Sheet 2. Salient features of the presentation

Sheet 3. An excerpt from a project report -An introductory page

Sheet 4. Simplified equation for the field induced by a dipole originating from a spherical volume element with uniform magnetic susceptibility, its radius in relation to the distance to the point where the indiced field is relevant. This radius-distance consideration for packing the spheres along a vector length.And the equation for the number of such dipoles along the close-packing direction.

Sheet 5. Extension of the above considerations to two and three dimensional expanses to cover the entire material of a macroscopic specimen.

Sheet 6. Equation for the Shielding constant(induced field analog) s for the contribution from along a vector,two dimensional packing of the vectors and similar three dimensional depiction.

Sheet 7. Tabulation of calculated values.

Sheet 8. Results for the various locations of the center of the inner cavity.

Sheet 9. Results for the case of ellipsoidal shapes.

Sheet 10. A presentation of the case of possible application to NMR studies of membrane transport.

Sheet 11. Polar coordinate definitions and trends of the various factors appearing in the equations.

Sheet 12. ELLIPSOIDS- a pocket calculator calculation and tabulation of computer calculated values for extended sets of cavity center locationssimilar to sheet 8.

Sheet 13. Calculation of induced fields by the same method in regions inside and outside the magnetized specimen.

Sheet 14. Methods based on bulk susceptibility differences.

Sheet 15. Various sample shapes in membrane transport context and other NMR situations.

Sheet 16. A typical feasibility demonstration of simplicity of this procedure to such contexts as in sheet 15.

Sheet 17. Computer program results of ellipsoids of different a/b ratios for demagnetization factors.

Sheet 18. Similarity of figures & drawings/plots obtained by this induced field calculations and the reproduced images of objects by NMR imaging.

Sheet 19. Various shapes encountered in NMR where this procedure of induced field calculation seems to be conveniently applicable.

Sheet 20. Summary and references

__contents of SHEET#20__

SUMMARY:

The considerations of possibilities of calculating demagnetization factors(1) by the methods similar to lattice summing provide a possibility to calculate these factors using even a simple pocket calculator(12) for the standard shapes of homogeneously magnetized specimens.This enables the calculation of induced magnetic fields inside the specimen at various points conveniently and also how these contributions at a given point differ depending on the polar and azimuthal angles(5,11) of the contributing elements from within the specimen.There are experimental situations(10,14,19) where inhomogeneities present in the sample are advantageously used(13,16) for assigning the NMR signal characteristics from different regions of the sample. It is also being pointed out that these induced field distributions expressed as field inhomogeneities(13,18) within the sample can be calculated more discretely by the above methods and can be adding to the methods available for optimizing contrasts in images if necessary with added susceptibility modifying reagents and these depend on the shapes of the samples and that of the regions considered within the sample. The demagnetization factors calculated for a few standard shapes are reported(17) for comparison with the standard tabulated values. An effort is made to depict the pointwise induced field values from the perspectives of image-representations to make it appreciable that such pictures can be visually indicative18 of the actual modifications required for a given situation to reduce the necessity for the enormous numerical tabulations(7,17,13) which would render even this simplified calculations relatively tedious.

NUMBERS OCCURING AS (SUPERSCRIPTS) REFER TO THE SHEET # ON THE POSTER

REFERENCES:

Readings for a better perspectiveof the microscopic and macroscopic aspects

1. Local-field Effects and Effective-medium theory: A Microscopic perspective D.E.Aspnes, American Journal of Physics, 50(8),1982, pages 704 to 708

2. Local Fields in Solids:microscopic aspects of dielectrics S.E.Schnatterly and C.Tario,Reviews of Modern Physics, vol 64,1992, pages 619-622.

3. Lattice-sum Methods for Calculating Electrostatic Interactions in Molecular Simulations Brock A.Luty, Ilaro G.Tironi and Wilfred F.van Gunsteren

Demagnetization Factor Calculations,Induced Field Effects

1. Effect Of Demagnetization On Magnetic Resonance Line Shapes In Bulk Samples: Apploication To Tungsten George Mozurkewich, H.I.Ringermacher and D.I.Bolef, Physical Review B, Vol 20(1), 1979 Pages 33-38.

2. Rapid Computation Of Magnetic Anomalies And Demagnetization Effects Caused By Bodies Of Arbitrary Shapes P.Vallbh Sharma, J. Geophysical Research, Vol.64 1966/11, Pages 89-107.

After a poster presentation (on the calculations of intramolecular shielding tensor at aromatic proton in benzene molecule )at the joint ISMAR-CA '98 (Aug.1998 at TU Berlin), the induced field calculations are now being extended to calculating a tensor-form shielding contribution due to the ring current in benzene!

__Benzene Molecule with the Delocalized Aromatic Charge cloud__