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.
