225 results about "Relaxation (NMR)" patented technology

A magnetic field measurement system that includes at least one magnetometer; at least one magnetic field generator; a processor coupled to the at least one magnetometer and the at least one magnetic field generator and configured to: measure an ambient background magnetic field using at least one of the at least one magnetometer in a first mode selected from a scalar mode or a vector mode; generate, in response to the measurement of the ambient background magnetic field, a compensation field using the at least one magnetic field generator; and measure a target magnetic field using at least one of the at least one magnetometer in a spin exchange relaxation free (SERF) mode which is different from the first mode.

Pulse sequences are applied to a fluid in an earth formation in a static magnetic field having internal gradients. From the received signals, relaxation and diffusion characteristics of the fluid are determined. The determination takes into account the internal field gradients.

Methods and systems for electron spin MRI (eMRI) and novel methods for fabricating N@C60 fullerenes using the discovery that certain endohedral fullerenes can be used as functional paramagnetic materials exhibiting increased relaxation times. These endohedral fullerenes provide improved labels for use in electron spin resonance (ESR) detection systems.

An MRI configuration comprising an MRI phantom positioned in a volume under investigation, wherein the MRI phantom has a chamber disposed in a housing and filled with a liquid, in which a gas bubble forms, the liquid nuclei which have an NMR relaxation time T1 of between 100 ms and 20 s, is characterized in that the chamber the MRI phantom a main chamber and a partial chamber, the main chamber being delimited from the partial chamber such that the gas bubble can completely enter the partial chamber due to its buoyancy by changing the spatial orientation of the MRI phantom in the gravitation field, and remains in the partial chamber in a measurement orientation of the MRI phantom due to its buoyancy. This eliminates imaging artefacts despite the presence of a gas bubble.

Pulse sequences are applied to a fluid in an earth formation in a static magnetic field and NMR spin echo signals are obtained. The signals are inverted to give T2 distributions at a plurality of depths. Similarities between logs of the T2 bins with resistivity and / or gamma ray logs are used to identify and subtract contributions to the NMR signal from oil. having internal gradients. From the received signals, relaxation and diffusion characteristics of the fluid are determined. The determination takes into account the internal field gradients. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

A time multiplex arrangement for presenting multiple samples to a single channel of NMR excitation / data acquisition includes means for rapid exchange of physical position between plural samples or sample portions from the measurement volume of the NMR instrument while said samples remain in a substantially the same homogeneous magnetic field. While a delay is imposed upon time evolution or relaxation of an NMR excited sample outside the sensitive volume of an RF resonator, another sample is actively excited within said RF resonator whereby the steps of NMR measurement are overlapped between at least two samples.

The nuclear magnetic resonance spectrum of a sample, which is a target material analyzed, and changes in relaxation times of nuclear magnetic resonance signals are measured while the sample is irradiated with terahertz waves containing frequency components corresponding to peak portions of absorption or reflectance spectrum of the sample. On the basis of the changes in relaxation times, the relationship between peak portions and information about a three-dimensional structure, conformational alteration, molecular relaxation, and the like is observed, the peak portions being in the absorption or reflectance spectrum in the terahertz range of the sample.

A method for quantifying bitumen and / or water in a sample comprising bitumen, water and solids using a time-domain nuclear magnetic resonance pulse spectrometer is provided comprising the steps of: initially saturating the magnetization of the sample so that essentially no magnetization remains in the +Z axis; subjecting the sample to a sequence of radio-frequency pulses optimized for the measurement of bitumen and water in the sample; allowing the recording of the transverse relaxation (T2) echo trains after incremental longitudinal relaxation to produce a raw TD-NMR data set for the sample; and determining the amount of bitumen and water by means of a partial least squares optimization based chemometric model relating TD-NMR data sets obtained from a training set of samples comprising bitumen, water and solids to the training samples' corresponding reference values obtained from a standard analysis method for determining bitumen and water.

The viscosity η (in centipoise) of a heavy oil sample is determined according to an equation of the form lnηηg=-C⁢⁢1*(T-c′⁢246)c″⁢47.10+(T-c′⁢246),where T is the temperature of the heavy oil, T2LM is the logarithmic mean of the T2 distribution of the sample obtainable from nuclear magnetic resonance (NMR) measurements, c′=1.0±0.05, c″=1.0±0.04, ηg is the glass transition temperature viscosity of the heavy oil and a function of T2LM, and C1 is a variable which is a constant for the heavy oil and is a function of T2LM. Both C1 and ηg are considered functions of certain NMR values associated with the heavy oil sample, with ηg and C1 preferably estimated by empirically fitting data to the equations ln T2LM=a′+b′ ln ηg and ln T2LM=a″+b″C1, where a′, b′, a″ and b″ are constants.

Methods for detecting a liquid under a surface and characterizing Ice are provided The liquid may be a liquid hydrocarbon such as crude oil or fuel oil or mineral oil The surface may be ice, snow, or water, and the method may be practiced in an arctic region to detect oil spills, leaks, or seepages The methods may be used with a range finder to characterize marine ice The methods may include a nuclear magnetic resonance (NMR) tool with antenna to send a radio-frequency (RF) excitation pulse or signal into volume of substances being detected, detect an NMR response signal to determine the presence of the liquid of interest The NMR response may include a relaxation time element and an intensity level and may include a free induction signal (T2*), a spin echo signal (T2), a train of spin echo signals (T2), or a thermal equilibrium signal (T 1).

A method for quantifying bitumen and / or water in a sample comprising bitumen, water and solids using a time-domain nuclear magnetic resonance pulse spectrometer is provided comprising the steps of: initially saturating the magnetization of the sample so that essentially no magnetization remains in the +Z axis; subjecting the sample to a sequence of radio-frequency pulses optimized for the measurement of bitumen and water in the sample; allowing the recording of the transverse relaxation (T2) echo trains after incremental longitudinal relaxation to produce a raw TD-NMR data set for the sample; and determining the amount of bitumen and water by means of a partial least squares optimization based chemometric model relating TD-NMR data sets obtained from a training set of samples comprising bitumen, water and solids to the training samples' corresponding reference values obtained from a standard analysis method for determining bitumen and water.

The invention relates to a NMR food-borne pathogen rapid detection method based on paramagnetic nano-Fe probes. The invention belongs to the technical field of pathogen rapid detection in food safety. The method is dependent on an established nuclear magnetic resonance (NMR) detection method which can be used in detecting pathogens in food samples. With the influence of the paramagnetic nano-Fe probe paramagnetic properties upon the relaxation time of the NMR attenuated signals, the existence of the target pathogen in the sample is detected. Specific correspondences comprise: the paramagnetic nano-Fe probes show a linear relationship under a certain condition, wherein the larger the nano-Fe content is, the smaller the sample T2 / T1 value is. Therefore, target bacteria can be quantitatively detected within a certain range. The method can be used in rapid detection of harmful pathogens in food samples, and can be used in rapid screening of large batches of samples to be detected.

The invention provides a method for quickly detecting NMR (Nuclear Magnetic Resonance) food-borne pathogenic bacteria based on indirectly enriched Fe3O4 nano particles, and belongs to the field of quick food safety pathogenic bacteria detection technologies. The method depends on an established nuclear magnetic resonance detection method for detecting the pathogenic bacteria in a food liquid sample, and comprises the following steps of: bonding target bacteria by utilizing the primary antibody specificity; preparing a target train by utilizing Fe3O4 nanometer materials, wherein the target strain is marked by primary antibodies which are enriched in target by second antibody immunomagnetic beads; and then detecting whether a sample contains the target pathogenic bacteria or not by the influence of the paramagnetic and superparamagnetic characteristics of the Fe3O4 nano particles to the nuclear magnetic resonance relaxation time. The Fe3O4 nano particles are be used as the enrichment means and also can be used as detecting probes. The different and specific corresponding relation is that paramagnetic immunomagnetic beads show a linear relation under a certain condition, namely the higher the immunomagnetic bead content is, the smaller the T2 / T1 value of the sample is, and the target bacteria can be quantitatively detected within a certain scope. The method can be used for quickly detecting harmful pathogenic bacteria in the food sample, and thus the large quantity of samples to be detected can be quickly screened by using the method.

The embodiment of the invention discloses a method for compensating for signal losses of a coal sample centrifugal process in a nuclear magnetic resonance experiment. The method comprises the following steps: S100, selecting coal samples with different metamorphic degrees, performing nuclear magnetic resonance experimental testing on a saturated water coal sample, carrying out centrifugal testingon the saturated coal sample to obtain a centrifugal coal sample, carrying out nuclear magnetic resonance experimental testing on the centrifugal coal sample again, calculating a relaxation time cutoff value and making an aperture distribution curve of the two nuclear magnetic resonance; S200, carrying out low temperature nitrogen adsorption experiment testing on an original coal sample and calculating a specific surface area S and a pore volume V; and S300, on the basis of calculation of a surface relaxation rate, compensating for a signal loss amount of the coal sample after the centrifugalexperiment in the nuclear magnetic resonance experiment. Therefore, the nuclear magnetic signal loss generated by the centrifugal process is compensated, and the accuracy of the analysis result is improved.