Commercial Nuclear Magnetic Resonance Research Articles

Real-time calculation and visualization of spectra in field-cycled dynamic nuclear polarization spectroscopy

Field-cycled dynamic nuclear polarization (FC-DNP), which is based on the Overhauser effect, provides a new way to perform in vivo measurements of free radicals in biological systems. Since it measures the alterations of the nuclear magnetic resonance (NMR) signal in the presence of paramagnetic molecules, a customized program is usually needed in FC-DNP experiments to extract spectral information from the acquired NMR signals. While this program can be designed to calculate the spectrum after all the NMR signals are collected, the batch-processing mode inevitably causes delay and is not convenient for in vivo applications. In this paper, we report the development of a real-time DNP spectrum calculation and visualization program, called RT_DNP, for FC-DNP experiments. A dynamic data exchange (DDE) client was implemented to enable real-time receipt of the system information and the NMR signals from a commercial NMR console. The received NMR signals and experimental parameters were then used to calculate the DNP spectrum during the data acquisition. The real-time DNP spectrum calculation and visualization program was tested in experiments. A seamless integration of the program into a commercial NMR console has been achieved.

A high performance digital receiver for home-built nuclear magnetic resonance spectrometers

The design and construction of a high-performance, low-cost, and easy to assemble quadrature digital receiver for a home-built nuclear magnetic resonance (NMR) spectrometer is described. Critical synchronization and timing issues are considered and solutions are discussed. The performance of the receiver is compared to that of a modern commercial NMR spectrometer. Advantages of this system include excellent passband flatness and delay flatness, very sharp filter cutoff, high dynamic range, bandwidths up to 30 MHz, and perfect balance between the quadrature channels with no component matching or adjustment.

Gas-Phase NMR Spectroscopy

Nuclear Magnetic Resonance (NMR) spectroscopy has become one of the most powerful tools available to the chemist and biochemist for the study of structure and chemical exchange in a multitude of chemical systems. The phenomenon of nuclear magnetic resonance was first observed in 1946, and in these last five decades the field has grown tremendously. Today, almost every university chemistry department owns at least one commercial NMR spectrometer.

Magnetic field gradient system for nuclear magnetic resonance microimaging.

In this study we present an orthogonal magnetic field gradient system for nuclear magnetic resonance (NMR) microimaging applications. The construction details are given for a prototype assembly for proton microscopy inside a 50-mm vertical bore magnet, which is designed to fit into a commercial 300-MHz NMR probe. This system has been used to acquire images of the human spinal cord in vitro. Its performance has been evaluated and compared to that predicted by computer simulation.

Instrument Makers and Discipline Builders: The Case of Nuclear Magnetic Resonance

Crucial to the establishment of a scientific discipline is a body of knowledge organized around a set of instruments, interpretive techniques, and regimes of training in their application. In this paper, we trace the involvement of scientists and engineers at Varian Associates in the development of nuclear magnetic resonance (NMR) spectrometers from the first demonstrations of the NMR phenomenon in 1946 to the definitive takeoff of NMR as a chemical discipline by the mid-1960s. We examine the role of Varian scientists in constructing several models of NMR instruments for research scientists in the 1950s and the Varian efforts to influence the adoption of NMR as a standard tool for chemical analysis through Varian-supported publications, participation in scientific meetings, collaborations with academic chemists, workshops, and postdoctoral fellowships. Special attention is devoted to the development of the Varian A-60, the first commercial NMR instrument intended for the broadly trained chemist rather than a custom-built tool for the research specialist. Drawing on an examination of the use-rate of NMR instruments in chemical literature, the assessment of NMR in the chemical review literature by practitioners, and indicators of the establishment of a suitable funding environment for the growth of physics-based scientific instrumentation in the post-Sputnik era, we argue that the establishment of NMR as a discipline coincided with the adoption of the A-60 in the mid-1960s. During the period of our study, Varian Associates was a primary military contractor. This paper is intended to contribute to recent interest in the relation of military fundingto scientific enterprise during the Cold War and to the larger question of university-industry interactions in the growth of knowledge.

6] Modifications of older model nuclear magnetic resonance console for collection of multinuclear, multidimensional spectral data

Pursuant to the original description by Kay, Ikura, Tschudin, and Bax, a growing variety of double- and triple-resonance, three-dimensional (3D) and four-dimensional (4D) nuclear magnetic resonance (NMR) experiments have been developed. Although fully equipped commercial NMR spectrometer consoles produced after 1990 have been capable of performing these demanding experiments, earlier consoles lack the necessary decoupling capabilities and requisite number of transmitter channels. Thus, although the original two-dimensional (2D) triple-resonance experiments have been able to be carried out some of with a standard 1985 vintage Bruker Instruments AM-400 NMR spectrometer and BSV-3 X-nucleus decoupler, it was needed to make extensive modifications in order to perform multinuclear 3D and 4D experiments. Kay et al. described the adaptation of a Bruker AM console for early 3D and 4D triple-resonance experiments. With more extensive modifications, most of the current multinuclear 3D and 4D experiments have been able to be performed with older model Bruker Instruments AM-500 and AM-600 consoles and BSV-3 X-nucleus decouplers.

Nuclear magnetic resonance imaging in Marfan's syndrome

Detection and evaluation of aortic root and other cardiovascular abnormalities in patients with Marfan's syndrome are important in determining appropriate therapy and preventing premature mortality. To evaluate the role of nuclear magnetic resonance imaging (NMR) in this syndrome, 10 patients were evaluated using a 0.35 tesla commercial nuclear magnetic resonance imaging system. Findings from these studies were compared with data from other noninvasive tests as well as surgical follow-up. Results from these examinations indicate that NMR-derived measurements of aortic root diameter agree closely with echocardiographic measurements. In addition, NMR provides more complete anatomic detail than does echocardiography and can be utilized to assess and follow up virtually all patients with this syndrome.

Analysis of oil content of groundnuts by nuclear magnetic resonance spectrometry

AbstractOne hundred groundnut germplasm accessions were analysed for their oil content by the standard Soxhlet extraction procedure using petroleum ether: the results were compared using functional analysis with those obtained with a commercial nuclear magnetic resonance (n.m.r.) spectrometer. On another 78 experimental samples, oil content was first obtained using the n.m.r. method and the Soxhlet values were predicted using the above functional relationship. On the 78 samples the predicted values were highly correlated (r=0.972) with those obtained by Soxhlet extraction. The n.m.r. method is rapid, easy, acurate and non‐destructive.

The current status of NMR imaging.

A brief account is given of the current status of nuclear-magnetic-resonance (NMR) imaging for medical purposes. The procedures in present use for two- and three-dimensional NMR imaging are outlined and examples given. The quality of images approaches that of computerized tomography X-ray scans and demonstrates superior tissue discrimination and pathological discrimination. Guidelines for safe operation are discussed. Clinical trials of commercial NMR scanners at an advanced stage.

Nuclear magnetic resonance spectrometry as a quick method of determination of oil content in rapeseed

AbstractA comparison of results obtained by the traditional extraction method for determination of oil content in rapeseed and those achieved by a commercial nuclear magnetic resonance (NMR) spectrometer revealed a very high correlation (r=0.987) between the results. The advantage of the NMR method, in relation to the extraction method, is the shorter time needed for a test: the result will be available in the course of a few minutes. Moreover, no inflammable chemicals are needed for the test, and the apparatus does not take up much room. On the other hand the NMR spectrometer must be placed in a room with a constant temperature, the seed samples must have the same temperature as the adjustment samples, and the oil content must be determined on dry matter basis.