Biomedical subjects
Publications and source records attributed to S M Alnaimi.
The technique of nuclear magnetic resonance cryoporometry has been used to study the behavior of binary liquid mixtures of water and decane in porous sol-gel silicas. It was observed that the water preferentially adsorbed onto the silica surface and so was able to displace the decane from the pores.
We are using a novel NMR method, that has been developed in our laboratory and employs the depression of the freezing point (delta Tm) of confined liquid within porous media, to investigate the effect of pre-drying silica with average pore diameter ranging from 60 A to 1000 A. Cyclohexane was the confined liquid. Pre-drying was found to affect only the smallest pores. A study to compare partially filled and over-filled samples showed that the average delta Tm for partially filled samples is greater than for over-filled. We have also investigated the use of water as the absorbed liquid and compared results with those obtained from cyclohexane studies. Reasonable agreement was found but cyclohexane was more sensitive. The method is fast and is suitable for monitoring pore size distributions in the range of 50-1000 A.
MR-Relaxation (MRR) of 1H nuclei and MR-Cryoporometry (MRC) are combined to assess their feasibility and their potential in the study of bone microstructure. In principle, both techniques are able to give information on the structure of the pore space confining the fluids. Cow femur samples were carefully cored and cleaned in order to remove the natural fluids inside. For MRR analysis quasi-continuous distributions of T(1) and T(2) were obtained on samples fully saturated with water. Cyclohexane was used as a saturating fluid for MRC analysis. All T(1) and T(2) quasi-continuous distributions of water confined in bone samples are more than three decades wide, showing sufficient details to differentiate the samples. Pore size distributions obtained by MRC also differentiate the samples showing different characteristics of the pore space structure in the range of the highest sensitivity of the method (typically 3 to 100 nm, mesopore range). In particular, in samples where MRR shows a large fraction of signal with relaxation times below 10(2) ms, MRC indicates a large fraction of pore volume with pore sizes in the mesopore range.