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NMRS2005-ICMRBS; Hyderabad,Jan.16-21,2005

For more particulars about **participation of ***Dr.S.Aravamudhan* CLICK HERE

Go to view poster site
__Text of Abstract__

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**
Disentangling the Bulk Susceptibility Medium-Effects from the Molecular Local Chemical Shift Changes in **

Heterogeneous Biological Systems

S.Aravamudhan

*
Department of Chemistry*

North Eastern Hill University

PO NEHU Campus Mawkynroh Umshing

East Khasi Hills District

SHILLONG 793022 MeghalayaINDIA

EMail: saravamudhan@nehu.ac.in

*
*The importance of having to recognize the bulk susceptibility contributions to the induced fields at a nuclear spin site as distinctly different from the Chemical shift changes arising from the local molecular/atomic electron charge cloud circulation changes is becoming prominent in the studies of biological samples by the NMR techniques [1]. It is also has to be taken into consideration that the sample shape dependence of the Bulk Susceptibility contribution dominates the induced field distribution patterns more than the actual differences in Bulk susceptibility values from one sample to another. This bulk susceptibility contribution if can be tracked well, this can be advantageously used for obtaining the required image-quality in the MRI studies to extract the information on the system critically.

In this context it becomes necessary to have a simple mathematical procedure, which appropriately takes into consideration, the required validity point-dipole approximation by inherently built in the mathematical criteria, which is the basis for the calculation procedure.

An alternative simple summing procedure [instead of the complicated procedures of integration] is possible for the calculation of shape dependent Demagnetization Factors as can be known from the considerations of having to account for the bulk susceptibility effects in HR PMR Solids [2].

A perspective of this above simple summation procedure is that if a suitable polar coordinate axis system can be defined in the sample with the specific nuclear site as origin, then given a radial distance from the nucleus with the polar angular coordinates {謶} it is a simple matter of a pocket calculator calculation to arrive at the induced field contribution at the nuclear site. This calculation inherently generates a conical volume element with the defined origin at the apex. The required dimensions for this cone described this way can be predetermined as per the situational convenient [3].

This simple procedure seems capable of providing induced-field distribution patterns for specified shapes. And, also, if there is any prior information about the possible induced field distributions using these procedures an effort can be possibly made to infer about the shapes, which might be contributing to such patterns. This latter aspect has to be given a better investigation than

what at present was possible. This back and forth procedure might help to iterate and improve the inferences. The discussions in interpreting such bulk susceptibility by workers till now indicate

that this could be worthwhile tool in these contexts.

*It is intended to highlight this feature of the summing procedure in this presentation. However only a peripheral reference to applications to actual biological systems would be possible since it is necessary to emphasize and illustrate the simplicity of this mathematical procedure.*.

[1] DJ Philip, WA Bubb and PWKuchel, Mag.Res.Med., 51, 441-444 (2004)

[2]http://geocities.com/inboxnehu_sa/Poster_Sheets_Ampere.html

[3]http://geocities.com/amudhan20012000/Confview_link.html

CLICK HERE to display particulars of participation at the 17thEENC/32ndAmpere at France,Lille in Sept.2004

**View poster site**

Click HERE to display Abstract

SHEET_1
*Introduction* |
SHEET_2
*Introduction and index* |
SHEET_3
*Charge Cloud descriptions, Circulatory Movement of Charges,the Current flow* |
SHEET_4
*Charge circulation, magnetic Moments,and the point dipole approximation* |

SHEET_5
*Induced fields due to circulation of electrons causing Shielding deamgnaetization effects* |
SHEET_6
*Definitions of terms encountered while considering bulk susceptibility effects in NMR* |
SHEET_7
* A description of the mathematical procedure-[1] * |
SHEET_8
*A description of the mathematical procedure-[2] * |

SHEET_9
*A description of the mathematical procedure-[3] * |
SHEET_10 A description of the mathematical procedure-[4] |
SHEET_11
*Advantages of the simple summation procedure described in the previous sheets* |
SHEET_12
*An illustartion of calculation in specimen with inherently two parts* |

SHEET_13
*Specimen with regional spots of differing susceptibility values* |
SHEET_14
*Calculating the induced field at a point out sied the magnetized sphere* |
SHEET_15
*Specimen shapes other than ellipsoidal* |
SHEET_16
*refrences, summary and conclusions* |

__Related webpages__
CLICK HERE to display the page on the participation in the __"Meeting of Indian Biophysical Society"__* for the Year 2006*

Link below is to a Web Page Built by Dr.Aravamudhan on his participation in National Workshop on Bioinformatics and Computational Biology

**http://www.geocities.com/saravamudhan2002/BHU_BCB2006.html**

Image and link below is that of **B**iological **M**agnetic **R**esonance Data **B**ank-**B.M.R.B.**

**The Information about BMRB at Wisconsin University was acquired during the participation in the ICMRBS2005 at Hydrabad, India.**