A method for rapid acquisition of multiple scans of NMR sequences is presented. The method initially applies two RF-pulses in combination with two magnetic field gradient pulses of opposite polarity, different strength and different duration. The basic idea is to spoil any magnetization in any direction before by letting the system recover to some degree of restoration of the thermal equilibrium magnetization. Thereafter any pulse sequence can be applied, and the next scan may be run immediately after the end of the pulse sequence. Thus one avoids the 5 times T1 delay between each scan. A set of PFG sequences are presented that apply the spoiler recovery method for significant reduction in acquisition time, and the method has been verified at 0.5 Tesla as well as at 11.7 Tesla.

The 10th Bologna Conference on “Magnetic Resonance in Porous Media” was among the impressive events which, dedicated to the 600th anniversary of Leipzig University in December 2009, attracted colleagues from all over the world. The conference excursion took the participants to Ferropolis, a place north of Leipzig, equipped with impressive remainings of an old mining site, including huge conveyer bridges. Ferropolis also visualizes, in some way, Leipzig as a center of industry and science, with coal mining in its vicinity as one of the sources of industrial development and, hence, as a promoter of scientific progress. With pleasure I followed the invitation to talk on this occasion, by merging a plenary lecture with an after-dinner speech, about Leipzig’s special affection towards the topic of the conference. This contribution is a reproduction of my talk, accompanied by most of the presented slides.

NMR T2 distribution measurement is our chosen everyday method for NMR logging while drilling oil and gas wells. This method yields straightforward preparation and execution of the job as well as a normally easy interpretation of the measured data. For instance, gas and light oil discrimination against water is feasible by direct observation of the T2 distribution. A condition for this measurement method is a NMR logging tool that hardly moves while drilling and in addition uses a small static magnetic field gradient and short inter-echo time TE to be motion tolerant. Using data compression techniques, we can transmit by mud pulse telemetry the T2 distribution in real time from the borehole to the surface. This enables the drilling operator to use the NMR data for real-time decisions such as geosteering.

It is shown that internal gradient combined with the restricted diffusion effect can significantly influence the D-T2 cross plots, which are widely used for fluid typing in Nuclear Magnetic Resonance (NMR) well-logging applications. By using models that capture the most important features of the internal gradient in the sedimentary rocks, such effects can be accounted for in the D-T2 inversion process, making fluid typing more accurate.

Spongy-bone is a porous system characterized by a solid trabecular network immersed in bonemarrow and characterized by a different relative percentage of water and fats. In our previous paper, we demonstrated using calf bone samples, that water is more prevalent in the boundary zone while fats are rearranged primarily in the central zone of each pore. Moreover we showed that water internal gradient (Gi) magnitude from the samples was directly proportional to their trabecular bone density. Using a 9.4T MR micro-imaging system, here we evaluated T2, T2*, apparent diffusion coefficient (ADC) and Gi parameters from in vitro calf samples in spatially resolved modality, for both water and fat components. Moreover, relative percentages of water and fats were quantified from spectra. T2, T2* and ADC values are higher in fat than in water component. Moreover, the differential effects of fat and water diffusion result in different T2 and Gi behaviours. Our results suggest that differently from fat parameters, water T2*, ADC and Gi, may be reliable markers to assess not only trabecular bone density but, more generally, the status of spongy bone.

We present a Modulated Gradient Spin Echo pulse sequence that enables diffusion measurements with chemical shift resolution in the obtained spectra at higher modulation frequencies (1600 Hz) than previously obtained. The modulation is generated using a Carr- Purcell-Meiboom-Gill train of radiofrequency pulses in a constant gradient. To avoid distortions from eddy currents, a longitudinal eddy current delay was added between gradient modulation and spectrum acquisition. To suppress the effects from gradient-slicing and unwanted coherences, while maintaining high chemical shift resolution, short samples (height of 0.5 mm) were prepared in a 5 mm Shigemi™ tube. The pulse sequence was successfully tested on a sample of distilled water and a sample of a water-continuous microemulsion (Winsor’s type I).

We explore the use of correlations between susceptibility gradients, G0, and T2-relaxation (G0-T2), and show how the difference in response for oil and water with respect to G0 can be used for improved characterization of wettability of the internal surface in porous rock cores.

T2D TDNMR data is used to improve the assignment of the location of water in in-vitro pig skin. Whilst the corresponding 1d experiments report broad distributions of T2 and D respectively, two water components are resolved in the T2D data and are assigned as intraand extra-cellular water by considering the peak intensities in; whole defatted skin, a dermatomed slice of the top 0.4mm (mostly epidermis) and the remaining sub layer (dermis). The relative proportion of fast relaxing/fast diffusing water is largest in the epidermis section (which has a close packed cellular structure) so is assigned as intra-cellular water. Whilst there is more slowly relaxing/slowly diffusing water in the dermis section (which has fewer cells within a collagen network) so this is assigned as extra-cellular water. The observation that intra-cellular water relaxes fastest, suggests that the skin cells contain more exchangeable species, through which the water can relax, than the extra-cellular network. This assignment is supported when resolution is lost on repeated freezing, i.e. the cell walls are broken. Resolution is also lost on increasing the diffusion time from 50 to 100 and 150ms. This is likely partly due to relaxation but also due to diffusion through the cell membranes during the experiment and gives a measure of the cell wall permeability.

Kinetics of swelling and sorption behavior of unsaturated polyester nanocomposite (based on glycolyzed PET, maleic anhydride, styrene, and montmorillonite) synthesized by two different mixing methods, simultaneous and sequential is studied in acetic acid at different temperatures. The values of n in the transport equation are found to be below 0.5, showing non-Fickian or pseudo-Fickian transport in the polymers. The dependence of diffusion coefficient on the mixing methods and temperature has also been studied for the unsaturated polyester nanocomposite. The diffusion coefficients in simultaneous mixing samples decrease with an increase in the mixing time in the samples. In case of the sequential mixing samples, the diffusion coefficient increases with an increase in mixing time. The diffusion coefficient increases with an increase in temperature for all the unsaturated polyester nanocomposite samples. The sorption coefficient increases with an increase in the mixing time for all the samples synthesized by in-situ mixing method. The crosslink density (calculated from the CH3COOH swelling) ranges from 5.014 to 7.092 × 102 mol/cm3 for simultaneous mixed samples and 5.212 to 7.192 × 102 mol/cm3 for sequentially mixed samples.

In this study the diffusion coefficients for reaction components were determined for unimodal and bimodal pore size distribution and assuming transitional diffusion regime using a more realistic, Stewart-Johnson, method. It was found that determination of diffusion coefficient using the average pore size results in underestimated values. A comparison was made between the effects of unimodal and bimodal pore size distribution on diffusion coefficients. The governing differential equation for a single pellet for styrene production was solved by orthogonal collocation method. The effectiveness factor which is a key parameter in reactor design was determined for the reaction in practical range of pore size. It was found that the production rate and effectiveness factor are sensitive to pore size and pore size distribution and with certain pore size distribution a considerable improvement in production rate can be achieved.