High Pressure NMR

Nuclear magnetic resonance (NMR) spectroscopy has enjoyed a rich and productive history in the characterization of material properties and chemical transformations at elevated pressure. NMR at high pressure was used to explore a potential green alternative to traditional acidic pretreatment for the conversion of biomass to fuel. During the initial stages of this work it became evident that a new high pressure NMR probe was needed. A low cost, portable, high volume, stainless steel pressure reactor was modified to easily perform magnetic resonance relaxometry at industrially relevant pressures. Unlike existing pressurization strategies common to NMR spectroscopy, this approach is amenable to realistic samples that feature heterogeneity and have traditionally escaped NMR study at pressure. This pressure reactor/NMR probe combination is easily accommodated by most single-sided and other low magnetic field permanent magnet assemblies. The performance of this class of NMR probe in a variety of spectrometers with different magnet geometries has been tested and published on. Early success towards magnetic resonance imaging at pressure suggests interesting future research directions.

Portable Devices to Monitor Sample Rheology

Portable devices to monitor sample rheology can be developed by adapting the geometry of a probe/magnet assembly. Additional information can be gained by taking advantage of the various effects of flow on a signal (such as phase shifts, etc.). Using theory and experiment to optimize coil designs, we have built a magnetic sensor that can be submerged within a sample to obtain information about macroscopic properties in field-based settings. Coupling these specialized instruments with customized algorithms allows for automated, real-time signal analysis in non-laboratory environments.

Matrix Pencil Method

The matrix pencil method (MPM) is being explored for high resolution data processing in low field NMR. Improving the efficiency of data processing will expand the potential applications of portable NMR and enhance the quality of information that is gained from experiments. To operate in the low SNR regime and to analyze complex material dynamics, the MPM is a more adept signal processing technique than the conventional inverse Laplace transform (ILT), due to its high resolution and minimal computational requirements.

Water Content of Blood Plasma

Portable NMR relaxometry can be used to rapidly estimate the water content of blood plasma (PWC) in clinical settings. This is achieved by correlating the T1 and T2 decay constants to the percentage of water in plasma samples. The societal impact of this work is quite significant. A large percentage of medical decisions are based on laboratory tests, many of which are blood chemistry assays. However, the accuracy of blood tests can depend on PWC, which is not typically measured in clinical laboratories. Variance in PWC between patients can influence many test results, with blood electrolyte and metabolite measurements being perhaps the most notable. A rapid, NMR-based test to measure PWC can provide clinicians with a means to improve the accuracy of blood chemistry assays and diagnostic tests, which will improve patient care.

Emulsion Imaging

An emulsion is an unstable mixture of either oil dispersed in water or water dispersed in oil, which will lead to separation over time. In a factory setting, an emulsion will be subject to shear forces as it is moved through pipes to various stages of the assembly line causing the emulsion to breakdown. The emulsion breakdown phases will have different diffusion coefficients, so that a map of these coefficients will show the presence of different phases. An in-situ image of the emulsion may be taken on the assembly line and processed so that the factory can know that the emulsion is homogeneous as it is moved.