Готові списки джерел за темами / NMR/MRI methods

Добірка наукової літератури з теми "NMR/MRI methods"

Автор: Grafiati

Опубліковано: 8 червня 2024

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Статті в журналах з теми "NMR/MRI methods":

Takeda, Y., H. Maeda, K. Ohki, and Y. Yanagisawa. "Review of the temporal stability of the magnetic field for ultra-high field superconducting magnets with a particular focus on superconducting joints between HTS conductors." Superconductor Science and Technology 35, no. 4 (February 25, 2022): 043002. http://dx.doi.org/10.1088/1361-6668/ac5645.

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Abstract Superconducting magnets used in applications such as magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) require significant temporal magnetic field stability, which can be achieved when the MRI and NMR magnets are operated in the persistent current mode (persistent-mode) using superconducting joints. However, the ultra-high field MRI and NMR magnets are sometimes operated in the driven mode. Herein, we present an analysis of the temporal magnetic field drift and fluctuations observed for MRI and NMR magnets operating in the driven mode and an exploration of effective methods for stabilizing the temporal magnetic field fluctuations. In the last decade, substantial improvements have been achieved in superconducting joints between high-temperature superconductors (HTSs). These superconducting joints enable the development of persistent-mode ultra-high field magnets using HTS coils. Therefore, we herein review the superconducting joint technology for HTS conductors and describe the results of the persistent-mode operation achieved by a medium-field NMR magnet using an HTS coil. Particularly, the cutting-edge progress achieved concerning HTS superconducting joints, including joining methods, superconducting properties, and future prospects, is highlighted along with the issues that need to be addressed.

Ullah, Ubaid, Safia Bano, and Shoaib Saleem. "Evaluation of Central Nervous System Tuberculomas by Using Modern Diagnostic Techniques." Pakistan Journal of Medical and Health Sciences 16, no. 6 (June 22, 2022): 16–18. http://dx.doi.org/10.53350/pjmhs2216616.

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Aim: To assess central nervous system tuberculomas by using modern MRI techniques such as Diffusion MRI (dMRI), Nuclear magnetic resonance spectroscopy (NMR spectroscopy) and BOLD venographic imaging. Study design: A retrospective study design Study setting: From 5th Feb 2021 to 5th Feb 2022 at the department of Neurology of Ibe-e-Siena Hospital, Multan. Methods: A retrospective study was conducted in the neurology department of Ibe-e-Siena Hospital & Research Institute Multan from 5th February 2021 to 5th February 2022. A total of 100 patients with suspected intracranial tuberculomas were included in the study. Advanced MRI techniques, including Diffusion MRI (dMRI), Nuclear magnetic resonance spectroscopy (NMR spectroscopy) and BOLD venographic imaging and conventional MRI, was performed on the patients. The study was approved by the ethical committee of the hospital, and all the patients provided their written consent for inclusion in the study Results: NMR spectroscopy evaluation showed that N-acetylaspartate /Creatine and N-acetylaspartate /Choline ratios of tuberculomas did not differ significantly from malignant brain lesions (p>0.04). But the malignant brain lesion (2.59) were significantly higher than the Choline/Creatine ratio of tuberculomas(1.29). BOLD venographic imaging evaluation showed no hypointense peripheral ring in malignant brain lesions but showed complete and regular rings in 36 (58.1%) of tuberculomas. Conclusion: Diffusion MRI did not help distinguish tuberculomas from metastasis and gliomas. However, NMR spectroscopy did offer this advantage by evaluating their unique metabolite pattern. BOLD venographic imaging showed the presence of a complete peripheral hypointense ring helping in diagnosing tuberculomas Keywords: Intracranial tuberculomas, Nuclear magnetic resonance spectroscopy, diffusion MRI,

Banko, B. A., J. P. Milovanovic, and R. M. Maksimovic. "NMR diagnostic vallue inassessing laryngeal tumor." Acta chirurgica Iugoslavica 56, no. 3 (2009): 55–59. http://dx.doi.org/10.2298/aci0903055b.

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Aims: To evaluate diagnostic accuracy of pretreatment surgical magnetic resonance images (MRI) in assessment of patients with tumors of the larynx. Materials and methods: The study included 12 patients, 11 men and 1 women, age 614 years. All patients underwent laryngeal endoscopy and biopsy followed by MRI. The biopsy confirmed that all patient had squamous-cell carcinoma. The MRI images were evaluated for presence in supraglottic, glottic or subglottic region, invasion of submucosal space, cartilage, extension to extralaryngeal tissue, presence of regional lymph nodes in regions I to VII. Imaging data were compared to surgical findings. Results: In 11 patients (92%) the tumor was supraglottic and glotic region and in 1 (8%) subglottic. None of them had tumor only in one region. Paraglottic ivasion was seen in 9 (75%) and preepiglottic in 2 (50%) patients. Paraglottic and preepiglotic invasion in the same time was seen in 3(25%) patients. 7 (58%) patients had normal vocal cord mobility, 3 (25%) mobility was unilateral and 2 (17%) had no vocal cord mobility. Cartilage invasion has not been seen in present study. All patients had billateral limphadenopathy region II-IV. Extension to extralaryngeal tissue was absent. These findings were confirmed on surgery with high diagnostic accuracy. Conclusion: MRI has been shown to be a reliable method for presurgical assessment of patients with tumor of the larynx.

Sharma, Uma, and Naranamangalam R. Jagannathan. "Magnetic Resonance Imaging (MRI) and MR Spectroscopic Methods in Understanding Breast Cancer Biology and Metabolism." Metabolites 12, no. 4 (March 27, 2022): 295. http://dx.doi.org/10.3390/metabo12040295.

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A common malignancy that affects women is breast cancer. It is the second leading cause of cancer-related death among women. Metabolic reprogramming occurs during cancer growth, invasion, and metastases. Functional magnetic resonance (MR) methods comprising an array of techniques have shown potential for illustrating physiological and molecular processes changes before anatomical manifestations on conventional MR imaging. Among these, in vivo proton (1H) MR spectroscopy (MRS) is widely used for differentiating breast malignancy from benign diseases by measuring elevated choline-containing compounds. Further, the use of hyperpolarized 13C and 31P MRS enhanced the understanding of glucose and phospholipid metabolism. The metabolic profiling of an array of biological specimens (intact tissues, tissue extracts, and various biofluids such as blood, urine, nipple aspirates, and fine needle aspirates) can also be investigated through in vitro high-resolution NMR spectroscopy and high-resolution magic angle spectroscopy (HRMAS). Such studies can provide information on more metabolites than what is seen by in vivo MRS, thus providing a deeper insight into cancer biology and metabolism. The analysis of a large number of NMR spectral data sets through multivariate statistical methods classified the tumor sub-types. It showed enormous potential in the development of new therapeutic approaches. Recently, multiparametric MRI approaches were found to be helpful in elucidating the pathophysiology of cancer by quantifying structural, vasculature, diffusion, perfusion, and metabolic abnormalities in vivo. This review focuses on the applications of NMR, MRS, and MRI methods in understanding breast cancer biology and in the diagnosis and therapeutic monitoring of breast cancer.

Tse, T. Y., R. M. Spanswick, and L. W. Jelinski. "Quantitative evaluation of NMR and MRI methods to measure sucrose concentrations in plants." Protoplasma 194, no. 1-2 (March 1996): 54–62. http://dx.doi.org/10.1007/bf01273167.

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Prichard, James W., and Bruce R. Rosen. "Functional Study of the Brain by NMR." Journal of Cerebral Blood Flow & Metabolism 14, no. 3 (May 1994): 365–72. http://dx.doi.org/10.1038/jcbfm.1994.47.

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Nuclear magnetic resonance (NMR) methods allow a wide variety of noninvasive measurements to be made on living animals and humans. The most extensively developed application of such methods is magnetic resonance imaging (MRI) of the brain and other organs, which has already come to the attention of most biomedical scholars, many physicians, and even much of the lay public because of its widespread use in neurological research and medical diagnosis.

Hiltunen, Sami, Arttu Mankinen, Muhammad Asadullah Javed, Susanna Ahola, Martti Venäläinen, and Ville-Veikko Telkki. "Characterization of the decay process of Scots pine caused by Coniophora puteana using NMR and MRI." Holzforschung 74, no. 11 (November 26, 2020): 1021–32. http://dx.doi.org/10.1515/hf-2019-0246.

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AbstractWood decay is an economically significant process, as it is one of the major causes of wood deterioration in buildings. In this study, the decay process of Scots pine (Pinus sylvestris) samples caused by cellar fungus (Coniophora puteana) was followed by nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) methods. Altogether, 30 wood sample pieces were exposed to fungus for 10 weeks. Based on the decrease of the dry mass, the samples were categorized into three classes: decomposed (mass decrease 50–70%), slightly decomposed (10–50%), and nondecomposed (<10%). MRI made it possible to identify the active regions of fungus inside the wood samples based on the signal of free water brought by the fungus and arisen from the decomposition of wood carbohydrates. MRI implies that free water is not only created by the decay process, but fungal hyphae also transports a significant amount of water into the sample. Two-dimensional 1H T1-T2 relaxation correlation NMR measurements provided detailed information about the changes in the microstructure of wood due to fungal decomposition. Overall, this study paves the way for noninvasive NMR and MRI detection of fungal decay at early stages as well as the related structural changes.

Li, Jingyu, and Erni Ma. "Characterization of Water in Wood by Time-Domain Nuclear Magnetic Resonance Spectroscopy (TD-NMR): A Review." Forests 12, no. 7 (July 7, 2021): 886. http://dx.doi.org/10.3390/f12070886.

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This review summarizes the development of the experimental technique and analytical method for using TD-NMR to study wood-water interactions in recent years. We briefly introduce the general concept of TD-NMR and magnetic resonance imaging (MRI), and demonstrate their applications for characterizing the following aspects of wood-water interactions: water state, fiber saturation state, water distribution at the cellular scale, and water migration in wood. The aim of this review is to provide an overview of the utilizations and future research opportunities of TD-NMR in wood-water relations. It should be noted that this review does not cover the NMR methods that provide chemical resolution of wood macromolecules, such as solid-state NMR.

Li, Na, Yong Shen, Wenru Liu, Jun Mei, and Jing Xie. "Low-Field NMR and MRI to Analyze the Effect of Edible Coating Incorporated with MAP on Qualities of Half-Smooth Tongue Sole (Cynoglossus Semilaevis Günther) Fillets during Refrigerated Storage." Applied Sciences 8, no. 8 (August 17, 2018): 1391. http://dx.doi.org/10.3390/app8081391.

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Nondestructive and fast measurement and characterization of fish is highly desired during various processing treatments. This research investigated the effectiveness of low field LF-NMR and MRI as fast monitoring techniques to estimate the qualities of half-smooth tongue sole fillets treated with edible coating combined with modified atmosphere packaging during refrigeration. T2 relaxation spectra showed three peaks representing bound water (T21), immobile water (T22), and free water (T23), respectively. pT22 accounted for the largest proportion of three types of water, followed by pT23. The weighted MRI provided the internal structure information associated with different samples, indicting the combination of edible coating and MAP (70% CO2 + 30% N2) is the best performance in the maintenance of qualities and freshness of HTS fillets. All results demonstrated that the combination of LF-NMR and MRI as fast and nondestructive methods have great potential to monitor qualities deterioration and predict shelf life in of HTS fillets during refrigerated storage.

Prichard, James W. "Neurorehabilitation: Three New NMR Tools." Neuroscientist 4, no. 4 (July 1998): 231–35. http://dx.doi.org/10.1177/107385849800400411.

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NMR methods suitable for neurological diagnosis and research have proliferated since the biomedical NMR era began with the introduction of MRI in the late 1970s. The versatility and noninvasive nature of NMR present special opportunities for the study of tissue repair in the nervous system. Longitudinal observations of anatomical, functional, and biochemical aspects of repair processes through well-established NMR techniques are already feasible. Three newly developed techniques that promise to extend the range and depth of NMR work on neurorehabilitation are discussed in this article. These new techniques allow for the detection of 1) nerve fiber bundle orientation through the diffusional anisotropy of axoplasmic and interstitial water, 2) signs of neural activation within the first few hundred milliseconds after task onset, and 3) two-dimensional mapping of biochemical changes associated with tissue damage and repair. NEUROSCIENTIST 4: 231–235, 1998

Більше джерел

Дисертації з теми "NMR/MRI methods":

Randtke, Edward Alexander. "Development and Evaluation of Exchange Rate Measurement Methods." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/314652.

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Exchange rate determination allows precise modeling of chemical systems, and allows one to infer properties relevant to tumor biology such as enzyme activity and pH. Current exchange rate determination methods found via Contrast Enhanced Saturation Transfer agents are not effective for fast exchanging protons and use non-linear models. A comparison of their effectiveness has not been performed. In this thesis, I compare the effectiveness of current exchange rate measurement methods. I also develop exchange rate measurement methods that are effective for fast exchanging CEST agents and use linear models instead of non-linear models. In chapter 1 I review current exchange rate measurement methods. In chapter 2 I compare several of the current methods of exchange rate measurement, along with several techniques we develop. In chapter 3 I linearize the Quantifying Exchange through Saturation Transfer (QUEST) measurement method analogously to the Omega Plot method, and compare its effectiveness to the QUEST method. In chapter 4, I compare the effectiveness of current exchange rate theories (Transition State Theory and Landau-Zener theory) in the moderate coupling regime, and propose our own combined Eyring-Landau-Zener theory for this intermediate regime. In chapter 5 I discuss future directions for method development and experiments involving exchange rate determination.

Javed, M. A. (Muhammad Asadullah). "Advanced liquid and gas NMR methods for probing topical materials." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526222493.

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Abstract The present thesis exploits advanced liquid and gas NMR methods for the characterization of various interesting materials. The methods used to study the structural properties of thermally modified wood, ionic liquids, cements, shales, and porous organic cages include MRI, NMR cryoporometry, Laplace NMR, multidimensional Laplace NMR, as well as ¹²⁹Xe and ¹⁹F NMR. The commonality factor in all the studies is the usage of either inherent or introduced liquid or gas molecules to probe the topical materials. The MRI method was utilized to visualize the water absorption phenomena in the thermally modified pine wood. High-resolution images made it possible to observe the spatial distribution of free water and the changes in the rate of absorption of water in wood samples modified at different temperatures. The images also helped to resolve the individual resin channels. T₂ maps enabled us to observe the changes in the relaxation values of free water in thermally modified wood as compared to their unmodified reference wood samples. The multidimensional Laplace NMR methods were exploited to study the structural and dynamical properties of a novel halogen-free, boron-based ionic liquid (hf-BIL). NMR self-diffusion (D) experiments showed the presence of two coexisting dynamic phases in hf-BIL. Multidimensional D − T₂ correlation experiments made it possible to determine the T₂ relaxation times of the slow and fast diffusing phases. T₂ − T₂ relaxation exchange measurements allowed quantifying the exchange rates of anions and cations between the phases. Moreover, the theoretical modeling of the experimental data revealed that the slow diffusing phase was composed of anion-cation aggregates, while the fast diffusing phase was comprised of free anions and cations. ¹²⁹Xe NMR analysis of the xenon adsorbed in the cements and shales helped us to determine their porous structures. The method exploits the high sensitivity of the chemical shift of ¹²⁹Xe to its local environment. The chemical shift value of ¹²⁹Xe enabled us to estimate the size of the mesopores in the cement samples. The exchange spectroscopy (EXSY) measurements were used to determine the exchange rates between the free gas and mesopores of the cement samples. ¹²⁹Xe NMR spectra of the shale samples provided information about pore sizes and paramagnetic compounds. ¹H NMR cryoporometry measurements of the shale samples immersed in acetonitrile made it possible to analyze the pore size distribution ranging from 10 to over 100 nm. Moreover, T₂ − T₂ exchange measurements helped us to quantify the exchange rates of acetonitrile in the shale samples. Xenon and SF₆ were used as internal reporters to gain versatile information on adsorption phenomena in the cage and window cavities of the crystalline porous organic cages. ¹²⁹Xe NMR analysis of the adsorbed xenon helped us to determine the diffusion coefficients and activation energy of diffusion as well as thermodynamic parameters. With the help of T₂ relaxation time values, it was possible to estimate the exchange rates between cage and window cavities. Chemical exchange saturation transfer (CEST) experiments resolved a window cavity site, which arises from crystal defects in porous organic cages. In addition, ¹⁹F NMR analysis made it possible to estimate the relaxation rates and diffusion coefficients of SF₆ gas in porous organic cages. Modelling of the T₁, T₂ and diffusion data confirmed that the cage to window exchange is the completely dominating mechanism for ¹²⁹Xe T₂ relaxation. T₁ relaxation is dominated by diffusion modulated dipole-dipole relaxation (DDinter) and chemical shift anisotropy (CSA) relaxation due to local cavity mobility. Whereas, in case of SF₆ T₂ data, the dominating mechanism is diffusion modulated dipole-dipole relaxation and for T₁ the local tumbling of SF₆ in cage cavity is the key dynamics behind the dipole-dipole and CSA mechanisms
Original papers The original publications are not included in the electronic version of the dissertation. Javed, M. A., Kekkonen, P. M., Ahola, S., & Telkki, V.-V. (2015). Magnetic resonance imaging study of water absorption in thermally modified pine wood. Holzforschung, 69(7), 899–907. https://doi.org/10.1515/hf-2014-0183 Javed, M. A., Ahola, S., Håkansson, P., Mankinen, O., Aslam, M. K., Filippov, A., … Telkki, V.-V. (2017). Structure and dynamics elucidation of ionic liquids using multidimensional Laplace NMR. Chem. Commun., 53(80), 11056–11059. https://doi.org/10.1039/c7cc05493a http://jultika.oulu.fi/Record/nbnfi-fe2017102750335 Javed, M. A., Komulainen, S., Daigle, H., Zhang, B., Vaara, J., Zhou, B., & Telkki, V.-V. (2019). Determination of pore structures and dynamics of fluids in hydrated cements and natural shales by various ¹H and ¹²⁹Xe NMR methods. Microporous and Mesoporous Materials, 281, 66–74. https://doi.org/10.1016/j.micromeso.2019.02.034 http://jultika.oulu.fi/Record/nbnfi-fe2019041712678 Komulainen, S., Roukala, J., Zhivonitko, V. V., Javed, M. A., Chen, L., Holden, D., … Telkki, V.-V. (2017). Inside information on xenon adsorption in porous organic cages by NMR. Chemical Science, 8(8), 5721–5727. https://doi.org/10.1039/C7SC01990D http://jultika.oulu.fi/Record/nbnfi-fe201709288804 Håkansson, P., Javed, M. A., Komulainen, S., Chen, L., Holden, D., Hasell, T., … Telkki, V.-V. (2019). NMR relaxation and modelling study of the dynamics of SF₆ and Xe in porous organic cages. Manuscript

Amor, Nadia [Verfasser]. "Novel methods and applications of NMR and MRI : low-power RF excitation and hyperpolarized xenon-129 / Nadia Amor." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1021937592/34.

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Guerroudj, Feryal. "Dispositifs et méthodes RMN pour la caractérisation des écoulements et des transferts en milli-canaux." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0273.

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Notre étude vise à mettre en œuvre, par des moyens peu coûteux, des dispositifs spécifiques pour l'étude des écoulements et des phénomènes de transfert dans les systèmes milli-fluidiques et à optimiser les méthodes de RMN/IRM pour leur caractérisation. Deux applications en milli-fluidique ont été développées. La première porte sur le suivi du régime d'écoulement et la caractérisation d'instabilités hydrodynamiques ayant lieu dans les micro-mélangeurs. La seconde porte sur la visualisation du développement d'un biofilm dans un capillaire de dimensions submillimétriques et la caractérisation de l'hydrodynamique en présence de ce biofilm. Pour chaque application, un dispositif spécifique a été mis en place, comprenant le système milli-fluidique et la bobine radiofréquence (RF) adaptée à la géométrie et aux dimensions du système. Les bobines milli-fluidiques ont été fabriquées par gravure sur des substrats flexibles en cuivre/Kapton®. Avec les paramètres géométriques considérés, les simulations RF ont montré que les milli-coils produisent un champ intense et homogène et les mesures IRM démontrent une augmentation du rapport signal/bruit par rapport à une bobine commerciale MicWB40, ce qui a permis une analyse détaillée des phénomènes milli-fluidiques dans les deux cas d'étude
Our study aims to implement, with a low-cost methodology, specific devices to study flows and transfer phenomena in milli-fluidic systems and to optimize NMR/MRI methods for their characterization.Two milli-fluidic applications have been developed. The first one consists in the study of the flow regime and hydrodynamic instabilities occurring in micromixers. The second one in the study of the growth of a biofilm in a capillary of submillimeter dimensions and the characterization of the hydrodynamics of the flow in presence of this biofilm. For each application, a specific device was set up, including the milli-fluidic system and the radio frequency (RF) coil adapted to the geometry and dimensions of the system. The milli-coils were fabricated by etching on flexible copper/Kapton® substrates. With the considered geometrical parameters, RF simulations have shown that milli-coils produce an intense and homogeneous field and MRI measurements demonstrate an improvement of the signal-to-noise ratio compared to the commercial MicWB40 probe, which allows the detailed analysis of the above mentioned milli-fluidics phenomena

Silva, Arnaldo Peixoto da. "Acoplamento de técnicas espectrométricas com métodos quimiométricos de classificação e calibração multivariada em alimentos." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3556.

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Este trabalho de pesquisa descreve três estudos de utilização de métodos quimiométricos para a classificação e caracterização de óleos comestíveis vegetais e seus parâmetros de qualidade através das técnicas de espectrometria de absorção molecular no infravermelho médio com transformada de Fourier e de espectrometria no infravermelho próximo, e o monitoramento da qualidade e estabilidade oxidativa do iogurte usando espectrometria de fluorescência molecular. O primeiro e segundo estudos visam à classificação e caracterização de parâmetros de qualidade de óleos comestíveis vegetais utilizando espectrometria no infravermelho médio com transformada de Fourier (FT-MIR) e no infravermelho próximo (NIR). O algoritmo de Kennard-Stone foi usado para a seleção do conjunto de validação após análise de componentes principais (PCA). A discriminação entre os óleos de canola, girassol, milho e soja foi investigada usando SVM-DA, SIMCA e PLS-DA. A predição dos parâmetros de qualidade, índice de refração e densidade relativa dos óleos, foi investigada usando os métodos de calibração multivariada dos mínimos quadrados parciais (PLS), iPLS e SVM para os dados de FT-MIR e NIR. Vários tipos de pré-processamentos, primeira derivada, correção do sinal multiplicativo (MSC), dados centrados na média, correção do sinal ortogonal (OSC) e variação normal padrão (SNV) foram utilizados, usando a raiz quadrada do erro médio quadrático de validação cruzada (RMSECV) e de predição (RMSEP) como parâmetros de avaliação. A metodologia desenvolvida para determinação de índice de refração e densidade relativa e classificação dos óleos vegetais é rápida e direta. O terceiro estudo visa à avaliação da estabilidade oxidativa e qualidade do iogurte armazenado a 4C submetido à luz direta e mantido no escuro, usando a análise dos fatores paralelos (PARAFAC) na luminescência exibida por três fluoróforos presentes no iogurte, onde pelo menos um deles está fortemente relacionado com as condições de armazenamento. O sinal fluorescente foi identificado pelo espectro de emissão e excitação das substâncias fluorescentes puras, que foram sugeridas serem vitamina A, triptofano e riboflavina. Modelos de regressão baseados nos escores do PARAFAC para a riboflavina foram desenvolvidos usando os escores obtidos no primeiro dia como variável dependente e os escores obtidos durante o armazenamento como variável independente. Foi visível o decaimento da curva analítica com o decurso do tempo da experimentação. Portanto, o teor de riboflavina pode ser considerado um bom indicador para a estabilidade do iogurte. Assim, é possível concluir que a espectroscopia de fluorescência combinada com métodos quimiométricos é um método rápido para monitorar a estabilidade oxidativa e a qualidade do iogurte
This research work describes three studies of chemometric methods employed for the classification and characterization of edible oils and its quality parameters through Fourier Transform mid infrared spectroscopy and near infrared spectroscopy, and for the monitoring the oxidative stability and quality of yogurt using fluorescence spectroscopy . The first and second studies aimed the classification and characterization of edible oil and its quality parameters using Fourier Transform mid infrared spectroscopy (FT-MIR) and near infrared spectroscopy (NIR) measurements, respectively. Kennard-Stone algorithm was used for selecting the training set, after a principal component analysis (PCA) was applied. The discrimination of canola oils from sunflower, corn and soybean was investigated using SVM-DA, SIMCA and PLS-DA. The quality parameters refraction index and relative density of edible oil was investigated using partial least squares (PLS), iPLS, LS- SVM multivariate calibration of FT-MIR and NIR data were evaluated. Several preprocessing alternatives (first derivative, multiplicative scatter correction, mean centering, orthogonal signal correction and standard normal variate) were investigated by using the root mean square error of validation cross validation (RMSECV) and prediction (RMSEP), as control parameters. In fact, the methodology developed is proposed for direct relative density and refraction index in edible oils and their classification, requiring a few minutes per sample without any previous treatment. The third study aimed to evaluate the oxidative stability and quality of yogurt stored at 40C with light or dark using the combined parallel factor (PARAFAC) analysis and fluorescence spectroscopy. PARAFAC analysis of the fluorescence landscapes exhibited three fluorophores present in the yogurt, where, at least one of them was strongly related to the storage conditions. The fluorescence signal was resolved into excitation and emission profiles of the pure fluorescent compounds, which are suggested to be vitamin A, tryptophan and riboflavin. Regression model based on PARAFAC scores for riboflavin were built using the scores obtained in the first day as dependent variable and the scores obtained during the storage as independent variable. It was clear demonstrated that the slope of the analytical curve has become smaller throughout the experiment. Therefore, riboflavin level could be considered a good indicator for the yogurt stability. Thus, it is concluded that fluorescence spectroscopy in combination with chemometrics has a potential as a fast method for monitoring the oxidative stability and quality of yogurt

Park, BuSik Collins Christopher M. "Development of RF coils and pulsing methods for NMR/MRI." 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-4490/index.html.

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Книги з теми "NMR/MRI methods":

Mitchell, Donald G. MRI principles. 2nd ed. Philadelphia, Pa: Saunders, 2004.

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Mitchell, Donald G. MRI principles. Philadelphia: Saunders, 1999.

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Brown, Jeffrey J. Practical MRI: A teaching file. Phialdelphia, Pa: Lippincott₋Raven, 1996.

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1961-, Debatin Jörg F., McKinnon G. C. 1955-, and Berry I, eds. Ultrafast MRI: Techniques and applications. Berlin: Springer, 1998.

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C, Brasch Robert, ed. MRI contrast enchancement in the central nervous system: A case study approach. New York: Raven Press, 1993.

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G, Bradley William, and Bydder G. M, eds. Advanced MR imaging techniques. London: Martin Dunitz, 1997.

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name, No. MRI atlas of orthopedics and traumatology of the knee. Berlin: Springer, 2003.

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Peter, Teller, ed. MRI atlas of orthopedics and traumatology of the knee. Berlin: Springer, 2003.

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Valk, J. Magnetic resonance in dementia. Berlin: Springer, 2002.

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Elster, Allen D. Questions & answers in magnetic resonance imaging. 2nd ed. St. Louis: Mosby, 2001.

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Частини книг з теми "NMR/MRI methods":

Duckett, Simon B., and Ryan E. Mewis. "Improving NMR and MRI Sensitivity with Parahydrogen." In Hyperpolarization Methods in NMR Spectroscopy, 75–103. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/128_2012_388.

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Duckett, Simon B., and Ryan E. Mewis. "Erratum to: Improving NMR and MRI Sensitivity with Parahydrogen." In Hyperpolarization Methods in NMR Spectroscopy, E1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-39728-8_428.

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Reymbaut, A., Y. Zheng, S. Li, W. Sun, H. Xu, I. Daimiel Naranjo, S. Thakur, et al. "Chapter 14. Clinical Research with Advanced Diffusion Encoding Methods in MRI." In New Developments in NMR, 406–29. Cambridge: Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781788019910-00406.

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Santos, Alexandre F., Fabricio M. Silva, Marcelo K. Lenzi, and José C. Pinto. "Infrared (MIR, NIR), Raman, and Other Spectroscopic Methods." In Monitoring Polymerization Reactions, 107–34. Hoboken, NJ: John Wiley & Sons, 2014. http://dx.doi.org/10.1002/9781118733813.ch6.

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Radovanović, Jelena, Nikola Vuković, and Vitomir Milanović. "Global Optimization Methods for the Design of MIR-THz QCLs Applied to Explosives Detection." In Terahertz (THz), Mid Infrared (MIR) and Near Infrared (NIR) Technologies for Protection of Critical Infrastructures Against Explosives and CBRN, 71–86. Dordrecht: Springer Netherlands, 2021. http://dx.doi.org/10.1007/978-94-024-2082-1_6.

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Bonny, Jean-Marie. "Methods and Applications of Quantitative MRI." In Annual Reports on NMR Spectroscopy, 213–29. Elsevier, 2005. http://dx.doi.org/10.1016/s0066-4103(05)56004-6.

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Freeman, Ray. "Magnetic resonance spectroscopy." In Magnetic Resonance in Chemistry and Medicine, 223–39. Oxford University PressOxford, 2003. http://dx.doi.org/10.1093/oso/9780199260614.003.0014.

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Abstract The most useful and immediate impact of magnetic resonance in medicine has undoubtedly been the ability to display images of living systems (MRI) but some scientists are more excited about an alternative avenue of research-the non invasive study of biochemistry within the human body. This is now generally referred to as MRS, or sometimes in vivo spectroscopy. The basic principle is very simple-focus attention on a restricted volume within a particular organ of the body and then study the high-resolution NMR spectrum from that site. The way in which that spectrum changes with variations in metabolism, disease, or drug treatment affords an unprecedented insight into human biochemistry. Unlike MRI, in vivo spectroscopy appears to offer the possibility of suggesting biochemical treatments for disease rather than merely a diagnosis of pathology. Progress in MRS has however been slower than in MRI, probably because the technical problems have been more severe. Magnetic resonance imaging quickly achieved wide spread acceptance because it promised better pictures than the well-established X-ray methods; in vivo spectroscopy had no true forerunner at all.

Hortelano, Sonsoles, Miriam Zeini, Paqui G. Través, and Lisardo Boscá. "Nitric Oxide and Cell Signaling: In Vivo Evaluation of NO‐Dependent Apoptosis by MRI and Not NMR Techniques." In Methods in Enzymology, 579–84. Elsevier, 2005. http://dx.doi.org/10.1016/s0076-6879(05)96049-7.

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Grimes, Mark I., and Michael D. Mantle. "Magnetic Resonance Methods Applied to the Study and Development of Cell Cultures and Bioreactors for Biopharmaceutical Production." In Magnetic Resonance and its Applications in Drug Formulation and Delivery, 244–77. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781788019996-00244.

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The use of therapeutic proteins is growing, with these accounting for half of the best-selling drugs in 2020. In light of this, the development of new analytical methods to ensure product quality in upstream bioprocessing is important, as well as maximising cell culture productivity. For this, the study of both cell cultures themselves and bioreactors is essential. Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) offer advantages over other techniques. One unique advantage is that both techniques do not require the use of optically transparent samples for analysis; this means that potential uses are plenty, with little to no sample preparation required. NMR spectroscopy allows for the study of cell cultures in vivo, from which relevant data can be obtained in real time, as well as other key characteristics of the culture. MRI provides a facile route to the understanding of flow behaviour within operating bioreactors, as well as the ability to see regions of cell growth. In both cases, this information provides valuable insight to continually improve bioprocesses and bioreactors even further.

"The Product Operator Formalism." In Essential Mathematics for NMR and MRI Spectroscopists, 561–97. The Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/bk9781782627975-00561.

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Density matrix calculations are very powerful but also very time-consuming and error-prone when done by hand. The product operator formalism provides a compact way of doing “back-of-the-envelope” density matrix operations. In order to contrast the density operator method with the product operator method and to make clear the genesis of the product operator formalism a short discussion of a density matrix calculation is performed. The Cartesian product operator method is then presented and the rules for its use are developed. Multiple quantum coherence is defined and its genesis and evolution in time are explored. Helpful visualisations of product operator evolutions are presented as rotation diagrams. Several NMR pulse sequences are analysed and a visual operator-tree approach to analysis is presented. Single-transition product operators are discussed in preparation for the treatment of coherence transfer and relaxation.

Тези доповідей конференцій з теми "NMR/MRI methods":

Wang, Zhen, and Hiroshi Takahashi. "Development of UV-Vis-NIR-MIR absorption spectroscopy for gemstone analysis." In Novel Optical Systems, Methods, and Applications XXV, edited by Cornelius F. Hahlweg and Joseph R. Mulley. SPIE, 2022. http://dx.doi.org/10.1117/12.2624632.

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Marques, Grazielle de Oliveira, Guilherme Rodrigues Fontes Moura, Gabriela Brill Ney, and Pablo Henrique da Costa Silva. "Neuromyelitis optica (NMO): treatment during pregnancy." In XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.284.

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Background: NMO is a demyelinating autoimmune disorder of the CNS which affects the optic nerves and the spinal cord. Method: review based on papers from 2016 to 2020. Platforms used: MEDLINE and Pubmed. The descriptors: “NMO” AND “Treatment”. Objective: to review therapeutic approaches and restrictions for NMO during pregnancy. Case report: G.V.L, 17 years, 23 weeks pregnant, diagnosis of NMO in Dec/2020, with progressive loss of visual acuity and limbs paresthesia. The patient received intravenous methylprednisolone pulses 1g/5 days, followed by 7 sessions of plasmapheresis (PLEX), showing partial symptoms remission, prednisone 60 mg was maintained. March/2021: she presented symptoms reissue, cranial MRI w/o: nerves signal alteration, chiasma and bilateral optical tracts. Spine MRI w/o: slight signal alteration in the dorsal root of the spinal cord, which extends from C1 to C4. Other 5 sessions of PLEX were attempted, without improvement. Results: during pregnancy, intravenous glucocorticoid, Rituximab and Eculizumab proved to be safe in the treatment of NMO. PLEX is indicated in cases of remissions resistant to medications. The therapy with immunosuppressants, such as methotrexate, mycophenolate mofetil and mitoxantrone, isn’t recommended. These immunosuppressants can cause miscarriage or pose a risk to the fetus. However, the immunosuppressant azathioprine has a safety profile in pregnancy; furthermore, it is considered the most appropriate maintenance treatment in combination with prednisone. Conclusion: due to the risk of miscarriage and teratogenicity, NMO treatment during pregnancy is restrict to intravenous glucocorticoids, rituximab and eculizumab, and in specific cases PLEX.

Ji, Yunkai, Jian Hou, Yongge Liu, and Qingjun Du. "Study on Formation and Dissociation of Methane Hydrate in Sandstone Using Low-Field Nuclear Magnetic Resonance Technology." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19316.

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Abstract Natural gas hydrate, as an unconventional resource, has been attracting increasing attention. Understanding the characteristics of methane hydrate formation and dissociation in porous media is important for developing gas hydrate-bearing reservoirs. This work discusses the use of low-field nuclear magnetic resonance (LF-NMR) technology to investigate the formation and dissociation of methane hydrate in the sandstone. In this work, an experimental assembly wherein methane hydrate can form and dissociate, is used to conduct LF-NMR measurements. LF-NMR, as a noninvasive measurement technology, combines the transverse relaxation time (T2) measurement with the magnetic resonance imaging (MRI). T2 measurements can explore the characteristics of methane hydrate formation and dissociation in core samples from a pore-scale perspective. MRI can display the spatial distribution of water from a core-scale perspective. The excess-gas method and the excess-water method are successively applied to form methane hydrate, and depressurization is applied to dissociate methane hydrate in the laboratory. The characteristics of methane hydrate formation and dissociation is studied in the sandstone. Experimental results show that the signal intensity of short T2 and long T2 decreases simultaneously in the process of the methane hydrate formation using the excess-gas method, indicating that methane hydrate is formed in both small and large pores. When using the excess-water method, the signal intensity of long T2 decreases, and the signal intensity of short T2 increases in the process of the methane hydrate formation, indicating that methane hydrate is mainly formed in large pores. Methane hydrate is dissociated simultaneously in both small and large pores when using the depressurization method. Water content in small pores gradually increases. Capillary pressure causes some water to remain in the core samples following dissociation. Water content in large pores decreases initially and then increases during depressurization. In the early stages of depressurization, more water leaves large pores than is generated by hydrate dissociation. In the later stages of depressurization, less water leaves the large pores than is generated by hydrate dissociation. This study may inspire the new understanding on distribution of fluid in sediments during the process of accumulation and exploitation of natural gas hydrates.

OLIVEIRA, G. A., S. BUREAU, C. M.-G. C. RENARD, and F. de CASTILHOS. "DETERMINATION OF INDIVIDUAL SUGARS IN PASSION FRUIT USING NIR AND MIR SPECTROSCOPIC METHODS." In XX Congresso Brasileiro de Engenharia Química. São Paulo: Editora Edgard Blücher, 2015. http://dx.doi.org/10.5151/chemeng-cobeq2014-1297-20030-145163.

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Abrantes, Maely Moreira de. "Radiological clinical evaluation of cerebral venous thrombosis." In XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.313.

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Background: Cerebral venous thrombosis (CVT) is a rare disorder, accounting for 0.5- 1% of cerebrovascular diseases and, in general, affects young people. Occurs due to occlusion of venous sinuses and cerebral veins, which are responsible for the venous drainage of the brain. Symptoms and clinical course are extremely variable, making diagnosis difficult. Objective: The present study aims to conduct a review of the literature on the clinical radiological evaluation in patients with cerebral venous thrombosis. Methods:This is a literature review based on the medical literature and scientific articles indexed in the Scientific Eletronic Library Online (SCIELO) and VHL- Brazil. Results: The evolution, introduction and use of relatively recent imaging techniques have contributed to the early diagnosis and treatment of patients with CVT. Skull computed tomography (CT) is usually the first examination performed in emergency care and can be normal in up to 50% of cases. Skull MRI associated with cranial angioresonance (MRA) are currently the exams of choice for the diagnosis of CVT in the acute, subacute and chronic phases. These tests allow a detailed assessment of the thrombus and tissue changes resulting from CVT. Digital angiography of the skull by catheterization is an invasive method and is considered the gold standard method for the diagnosis of CVT. It is reserved for cases in which NMR is not conclusive or when considering the performance of an endovascular procedure. Conclusions: Imaging studies are of great importance in the diagnosis. Although the venous angiographic study is essential, it is also important to observe the conventional sequences in order to allow a correct diagnosis.

Requião, Letícia Escorse, and Murilo Santos de Souza. "Neuroradiological markers of Vascular Cognitive Impairment after Stroke." In XIII Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/1516-3180.461.

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Background: Cognitive vascular impairment (CCV) is a frequent, but overlooked, possible consequence of stroke. Neuroimaging is essential for the evaluation of these patients with cognitive deficits supposedly secondary to vascular lesions, with Nuclear Magnetic Resonance (NMR) of the skull being the most sensitive method for identifying markers associated with CCV. The most relevant markers seem to be, among others, strategic location, severity of white matter changes, as well as the degree of atrophy of the medial temporal lobe. Objective: To assess the relationship between stroke and CCV using markers from skull MRI. Methodology: This is a systematic review of observational studies published between 2005 and 2020. The search was carried out in the PubMed and SciELO databases with the keywords consulted by the following MeSH and DeCS sites: “stroke”, “MRI”, “Vascular cognitive impairment”, using the boolean operator “and”. The PRISMA check-list was used to guide this review. Results: According to the eligibility criteria, eight studies were selected. “Event location” was the marker in MRI of the skull most frequently considered, being the object of evaluation in seven of the eight studies analyzed and proving to be a statistically significant marker (p <0.05) for the prediction of CCV in six of them. 75% of the studies included in this review evaluated the relationship between the presence of “hyperintensity in the white matter” at MRI and CCV. However, this marker was shown to be statistically significant in 50% of these studies. Conclusion: A review that brought together the assessment of a wide range of possible neuroradiological predictors of CVD after stroke had not been carried out so far. It would be particularly useful to evaluate the markers in a more homogeneous way in a study with a larger sample size, which would allow quantitative analysis to measure the influence of each predictor.

Hou, Xiaoyu, James J. Sheng, and Jiacheng Dai. "Experimental Study on the Effects if Ift Reduction on Water Blockage after Hydraulic Fracturing in Tight Sandstone Reservoirs Based on The NMR Method." In Gas & Oil Technology Showcase and Conference. SPE, 2023. http://dx.doi.org/10.2118/214189-ms.

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Abstract The current studies regarding the effect of interfacial tension (IFT) reduction on removing the water blockage of tight sandstones are significant, but the migration characteristics of trapped water in the stimulation process have not been researched. These issues lead to the stimulation mechanism of IFT reduction after hydraulic fracturing is unclear. In this work, a new coreflood platform was designed to simulate the water invasion, shut-in, and flowback process, and how the IFT affects the water blockage was further studied from pore levels. The oil production rates before and after shut-in were measured, which were used to detect the regained permeability of tight sandstones. The T2 spectrum signals, 1D frequency, and magnetic resonance imaging (MRI) based on the nuclear magnetic resonance (NMR) experiments were used to explore the migration characteristics of trapped water under different conditions. The results indicate that the core damage induced by water invasion is severe. The regained permeability is decreased to less than 25% after shut-in. IFT reduction is an effective way to improve the regained permeability, but the emulsification effect of fracturing fluid needs to be avoided, which will reduce the permeability of tight sandstones by the Jiamin effect. The NMR signals of the 1D profile show the water saturation of cores gradually decreases from the fracture face to the exit end, which demonstrates that the water blockage occurs mainly in the area near the fracture face. The T2 spectrum signals show that the residual water saturation of mesopores and macropores after flowback can be reduced by decreasing the IFT values, but the reduction of residual water saturation in micropores is insignificant. This result demonstrates that the core damage caused by water blockage may mainly come from mesopores and micropores. Our study reveals a deeper mechanism of removing water blockage during the IFT reduction process, which can guide the application of surfactants in the oil field.

Schulz, Hartwig, Gennadi Gudi, and Andrea Krähmer. "Analysis of plant raw materials and extracts applying various vibrational spectroscopy techniques – possibilities and limitations." In OCM 2017 - 3rd International Conference on Optical Characterization of Materials. KIT Scientific Publishing, 2017. http://dx.doi.org/10.58895/ksp/1000063696-17.

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New methods using MIR, NIR and Raman spectroscopy in combination with various chemometric algorithms are presented which allow monitoring numerous plant samples very efficiently within a short time. Today portable FT-IR spectrometers are available which only need sample amounts of a few microliters or milligrams. In most cases, the measurements can be performed directly and non-destructively on the individual plant tissues or plant extracts. Generally, with IR and Raman spectroscopic techniques spectra are obtained which present characteristic key bands of individual plant components. These bands provide important information about the chemical composition of the investigated samples. Based on such markers spectroscopic analyses in principle allow the discrimination of different species, and even to classify chemotypes among the same species. Combination of vibrational spectroscopy and hierarchical cluster analysis provides a fast, easy and reliable method for chemotaxonomic characterization. The ability to rapidly monitor various plant components makes it possible to efficiently select high-quality single plants from wild populations as well as progenies of crossing experiments. Furthermore, the vibrational spectroscopic methods can also be used by the processing industry in order to perform fast quality checks of incoming raw materials as well as continuous controlling of production processes.

Stenzel, Olaf, and Ralf Petrich. "MIR/NIR/VIS spectrophotometric investigation of absorbing thin-film materials based on error function minimization by the method of conjugated gradients." In SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, edited by James D. Rancourt. SPIE, 1994. http://dx.doi.org/10.1117/12.185786.

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Romdhane Karoui, Abdul Mouenm Mouazen, Herman Ramon, Robert Schoonheydt, Eric Dufour, and Josse De Baerdemaeker. "A Comparison and Joint Use of VIS-NIR, MIR and Fluorescence Spectroscopic Methods for Differentiating Between the Manufacturing Process and Sampling Zones of Ripened Soft Cheese." In 2006 Portland, Oregon, July 9-12, 2006. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2006. http://dx.doi.org/10.13031/2013.21485.

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Звіти організацій з теми "NMR/MRI methods":

Wu, Bin, Lixia Guo, Kaikai Zhen, and Chao Sun. Diagnostic and prognostic value of miRNAs in hepatoblastoma: A systematic review with meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, November 2021. http://dx.doi.org/10.37766/inplasy2021.11.0045.

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Review question / Objective: Background and aim: Increasing evidence has revealed the valuable diagnostic and prognostic applications of dysregulated microRNAs (miRNAs) in hepatoblastoma (HB), the most common hepatic malignancy during childhood. However, these results are inconsistent and remain to be elucidated. In the present study, we aimed to systematically compile up-to-date information regarding the clinical value of miRNAs in HB. Methods: Articles concerning the diagnostic and prognostic value of single miRNAs for HB were searched from databases. The sensitivity (SEN), specificity (SPE), positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), area under the curve (AUC), and hazard ratios (HRs) were separately pooled to explore the diagnostic and prognostic performance of miRNA. Subgroup and meta-regression analyses were further carried out only in the event of heterogeneity. Results: In all, 20 studies, involving 264 HB patients and 206 healthy individuals, met the inclusion criteria in the six included literature articles. For the diagnostic analysis of miRNAs in HB, the pooled SEN and SPE were 0.76 (95% CI: 0.72–0.80) and 0.75 (95% CI: 0.70–0.80), respectively. Moreover, the pooled PLR was 2.79 (95% CI: 2.12–3.66), NLR was 0.34 (95% CI: 0.26–0.45), DOR was 10.24 (95% CI: 6.55–16.00), and AUC was 0.83, indicating that miRNAs had moderate diagnostic value in HB. For the prognostic analysis of miRNAs in HB, the abnormal expressions of miR-21, miR-34a, miR-34b, miR-34c, miR-492, miR-193, miR-222, and miR-224 in patients were confirmed to be associated with a worse prognosis. The pooled HR was 1.74 (95% CI: 1.20–2.29) for overall survival (OS) and 1.74 (95% CI: 1.31–2.18) for event-free survival (EFS), suggesting its potential as a prognostic indicator for HB. Conclusion: To the best of our knowledge, this is the first comprehensive systematic review and meta-analysis that examines the diagnostic and prognostic role of dysregulated miRNAs in HB patients. The combined meta-analysis results supported the previous individual finds that miRNAs might provide a new, noninvasive method for the diagnostic and prognostic analyses ofHB.