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"Glenn, David"
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Newfoundland rhapsody : Frederick R. Emerson and the musical culture of the Island
\"Frederick Rennie Emerson (1895-1972) was a dynamic presence in the cultural and intellectual life of Newfoundland and Labrador for much of the twentieth century. A musician, lawyer, educator, and folklore enthusiast, Emerson was a central figure in the preservation and mediation of Newfoundland culture in the tumultuous decades prior to and following Confederation with Canada in 1949.
Book
High-resolution magnetic resonance spectroscopy using a solid-state spin sensor
High-resolution nuclear magnetic resonance spectroscopy at the scale of single cells is achieved by combining a magnetometer consisting of an ensemble of nitrogen–vacancy centres with a narrowband synchronized readout protocol.
A new spin on NMR
The spin-hosting nitrogen–vacancy centres in diamond have the spatial sensitivity to detect the nuclear magnetic resonance (NMR) signals of single molecules. However, the spectral resolution of such schemes is not sufficient to unravel details of molecular structure. David Glenn
et al
. describe a sensitive magnetometer based on an ensemble of nitrogen–vacancy centres that, when combined with a customized pulsed readout protocol, can achieve a spectral resolution sufficient to resolve key chemical signatures at micrometre-scale spatial resolution. Such a scheme could enable NMR spectroscopy at the scale of single cells.
Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen–vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples
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,
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,
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, with sensitivity sufficient to detect the magnetic field produced by a single protein
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. However, the best reported spectral resolution for NMR of molecules using nitrogen–vacancy centres is about 100 hertz
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. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz
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) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency). Conventional, inductively detected NMR can provide the necessary high spectral resolution, but its limited sensitivity typically requires millimetre-scale samples, precluding applications that involve smaller samples, such as picolitre-volume chemical analysis or correlated optical and NMR microscopy. Here we demonstrate a measurement technique that uses a solid-state spin sensor (a magnetometer) consisting of an ensemble of nitrogen–vacancy centres in combination with a narrowband synchronized readout protocol
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,
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,
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to obtain NMR spectral resolution of about one hertz. We use this technique to observe NMR scalar couplings in a micrometre-scale sample volume of approximately ten picolitres. We also use the ensemble of nitrogen–vacancy centres to apply NMR to thermally polarized nuclear spins and resolve chemical-shift spectra from small molecules. Our technique enables analytical NMR spectroscopy at the scale of single cells.
Journal Article
Hyperpolarization-Enhanced NMR Spectroscopy with Femtomole Sensitivity Using Quantum Defects in Diamond
Nuclear magnetic resonance (NMR) spectroscopy is a widely used tool for chemical analysis and molecular structure identification. Because it typically relies on the weak magnetic fields produced by a small thermal nuclear spin polarization, NMR suffers from poor molecule-number sensitivity compared to other analytical techniques. Recently, a new class of NMR sensors based on optically probed nitrogen-vacancy (NV) quantum defects in diamond have allowed molecular spectroscopy from sample volumes several orders of magnitude smaller than the most sensitive inductive detectors. To date, however, NV NMR spectrometers have only been able to observe signals from pure, highly concentrated samples. To overcome this limitation, we introduce a technique that combines picoliter-scale NV NMR with fully integrated Overhauser dynamic nuclear polarization to perform high-resolution spectroscopy on a variety of small molecules in dilute solution, with femtomole sensitivity. Our technique advances the state of the art of mass-limited NMR spectroscopy, opening the door to new applications at the picoliter scale in drug and natural-product discovery, catalysis research, and single-cell studies.
Journal Article
Darwin's roadmap to the curriculum : evolutionary studies in higher education
\"This book serves to integrate the vast literature in the interdisciplinary field of Evolutionary Studies (EvoS), providing clear examples of how evolutionary concepts relate to all facets of life. Further, this book provides chapters dedicated to the processes associated with an EvoS education, including examples of how an interdisciplinary approach to evolutionary theory has been implemented successfully at various colleges, universities and degree programs. This book also offers chapters outlining a variety of applications to an evolution education, including improved sustainable development, medical practices, and creative and critical thinking skills. Finally, this book explores controversies surrounding evolution education and provides a roadmap to help shape a positive future for this approach to asking and answering questions\"-- Provided by publisher.
Book
Optical magnetic detection of single-neuron action potentials using quantum defects in diamond
Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution—e.g., magnetic resonance imaging methods and magnetoencephalography—or been restricted to biophysics studies of excised neurons probed with cryogenic or bulky detectors that do not provide single-neuron spatial resolution and are not scalable to functional networks or intact organisms. Here, we show that AP magnetic sensing can be realized with both single-neuron sensitivity and intact organism applicability using optically probed nitrogen-vacancy (NV) quantum defects in diamond, operated under ambient conditions and with the NV diamond sensor in close proximity (∼10 μm) to the biological sample. We demonstrate this method for excised single neurons from marine worm and squid, and then exterior to intact, optically opaque marine worms for extended periods and with no observed adverse effect on the animal. NV diamond magnetometry is noninvasive and label-free and does not cause photodamage. The method provides precise measurement of AP waveforms from individual neurons, as well as magnetic field correlates of the AP conduction velocity, and directly determines the AP propagation direction through the inherent sensitivity of NVs to the associated AP magnetic field vector.
Journal Article
Early Greek philosophy
\"The works of the early Greek philosophers are not only a fundamental source for understanding archaic Greek culture and the whole of ancient philosophy, but also a perennially fresh resource that has stimulated Western thought until the present day. This nine-volume edition presents all the major fragments from the sixth to the fourth centuries BC.\"-- Provided by publisher.
BOOK
Single-cell magnetic imaging using a quantum diamond microscope
This paper reports magnetic imaging of immunolabeled mammalian cells using nitrogen-vacancy centers in diamond and shows that the method can be used for quantitative profiling of markers.
We apply a quantum diamond microscope for detection and imaging of immunomagnetically labeled cells. This instrument uses nitrogen-vacancy (NV) centers in diamond for correlated magnetic and fluorescence imaging. Our device provides single-cell resolution and a field of view (∼1 mm
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) two orders of magnitude larger than that of previous NV imaging technologies, enabling practical applications. To illustrate, we quantified cancer biomarkers expressed by rare tumor cells in a large population of healthy cells.
Journal Article
Mapping the microscale origins of magnetic resonance image contrast with subcellular diamond magnetometry
Magnetic resonance imaging (MRI) is a widely used biomedical imaging modality that derives much of its contrast from microscale magnetic field patterns in tissues. However, the connection between these patterns and the appearance of macroscale MR images has not been the subject of direct experimental study due to a lack of methods to map microscopic fields in biological samples. Here, we optically probe magnetic fields in mammalian cells and tissues with submicron resolution and nanotesla sensitivity using nitrogen-vacancy diamond magnetometry, and combine these measurements with simulations of nuclear spin precession to predict the corresponding MRI contrast. We demonstrate the utility of this technology in an in vitro model of macrophage iron uptake and histological samples from a mouse model of hepatic iron overload. In addition, we follow magnetic particle endocytosis in live cells. This approach bridges a fundamental gap between an MRI voxel and its microscopic constituents.
Magnetic resonance imaging derives its contrast from local magnetic fields, however the connection between these fields and macroscale contrast has not been established through direct experiments. Here, Davis et al. use diamond magnetometry to map local magnetic fields within mammalian cells with sub-micron resolution and predict macroscale contrast.
Journal Article