Relaxation Time Of Water Research Articles

Water Proton Flow-NMR—A Novel Tool for Real-Time In-Line Process Monitoring in Biomanufacturing

Due to serious limitations, such as experiment duration, relaxation parameters, flow-NMR has limited applications to study structure and properties of a solute, especially, in the case of biomacromolecules, or in the manufacturing of biologics. Unlike conventional structural applications of NMR spectroscopy targeted towards complex solute biomacromolecules, its approaches directed to study the interactions between solute and solvent are less explored. However, in aqueous solutions, water molecules bear useful information about the state of solute molecule, in particular, biomacromolecules, e.g., proteins, actively interacting with water molecules. We have already demonstrated that water proton transverse relaxation rate, R2(1H2O), is a powerful indicator of protein aggregation sensitive to a wide range of aggregate sizes. Less is known about flow-NMR potential to explore water-proton interactions. Meanwhile, due to generally high water concentration in aqueous solutions of biomacromolecules and long relaxation times of water, many existing limitations of flow-NMR are lifted when it comes to study water-protein interactions mediated by relaxation. We report here the results obtained by a newly designed low-field benchtop flow-NMR instrument, which can monitor R2(1H2O) within the flow rates ranging from 0 to 50 mL/min. In our experiments, we demonstrated that R2(1H2O) in a flow depends on a flow rate in accordance with theoretically predicted residence time component. We also showed the sensitivity of water flow-NMR to the pH and ionic strength/conductivity of buffered aqueous solutions. R2(1H2O) was also found sensitive to the concentration of proteins in solution in the range from 0 to 50 mg/mL and flow rates from 0 to 50 mL/min. Our results pave the way for the application of water-proton flow-NMR as a noninvasive process analytical technology in continuous biomanufacturing. In a product flow, this unique technique could detect in-line concentration changes and protein aggregates.

Dielectric properties of water and ice: a unified treatment

Broadband dielectric spectra of water and ice reveal similar temperature run of the static permittivity, ε(0), and spectral shape of the Debye relaxation. We suggest an approach to describe these features uniformly. We extend to ice the model recently developed by us for water. The model explains the 6 orders magnitude difference between the Debye relaxation time in water and ice, as well as alike temperature behavior of ε(0), by bipolar diffusion of counter charges.

Effects of pretreatments on properties of microwave-vacuum drying of sweet potato slices

Pretreatments of blanching (BL); osmotic dehydration at 35°Brix of sucrose (OD); ultrasound in distilled water (UD), and ultrasound-assisted osmotic dehydration (UO) were carried out for microwave-vacuum drying (MVD) orange- and purple-flesh sweet potato slices, and effects on their properties were investigated in this study. UO had improvements effects on water loss, solid gain, and relaxation time of the samples compared to other pretreatments. Low-field nuclear magnetic resonance results offered a view of water state concerning the effects of different pretreatments on sweet potato. UD treatment following by BL showed a long relaxation time corresponding to the weaker degree of bound hydrogen proton or the greater freedom degree of hydrogen comparing to other pretreated samples. Differential scanning calorimetry parameters appeared to be sensitive to pretreatments by increased Tg value compared to blanched sample. The value of Tg shows that it does not depend only of the water content but also on the experimental conditions (pretreatments). The dried sweet potato exhibited amorphous structures as evidenced by the X-ray diffractograms due to the BL treatment and MVD. Concentration of total phenolics and anthocyanins were high in purple sweet potatoes, whereas content of vitamin C and total carotenoid were high in orange ones. Application of UO is suitable for retention of bioactive compound and stability of MVD sweet potato slices.

Data Correction for Surface Nuclear Magnetic Resonance in an Inhomogeneous Geomagnetic Field

In surface nuclear magnetic resonance, the geomagnetic field serves as the background field, and hydrogen protons in groundwater are excited with an alternating field at the Larmor frequency. However, in practice, an inhomogeneous geomagnetic field (IGF) or a magnetic anomaly caused by ferromagnetic materials will make the Larmor frequency nonunique, resulting in simultaneous on-resonance and off-resonance signals (composite resonance). If only the onresonance or off-resonance model is used to interpret the composite resonance data, the accuracy of the inversion analysis would be adversely affected. To solve this problem, we derived an expression for the composite magnetic-resonance free-induction-decay (FID) signal based on a layered model. The influence of IGF on the characteristic parameters of the FID signal was analyzed with simulation models, which showed that, with an increase in frequency offset and gradient, the relaxation time decreased prominently. We demonstrate an iterative correction method based on a frequency-depth curve. Through simulated and measured data, we show that the water content and relaxation time are consistent with ground truth after correction and that data consistency is improved.

Measuring intra-axonal T2 in white matter with direction-averaged diffusion MRI.

To demonstrate how the T2 relaxation time of intra-axonal water (T2a ) in white matter can be measured with direction-averaged diffusion MRI. For b-values larger than about 4000 s/mm2 , the direction-averaged diffusion MRI signal from white matter is dominated by the contribution from water within axons, which enables T2a to be estimated by acquiring data for multiple TE values and fitting a mono-exponential decay curve. If given a value of the intra-axonal diffusivity, an extension of the method allows the extra-axonal relaxation time (T2e ) to be calculated also. This approach was applied to estimate T2a in white matter for 3 healthy subjects at 3 T, as well as T2e for a selected set of assumed intra-axonal diffusivities. The estimated T2a values ranged from about 50 ms to 110 ms, with considerable variation among white matter regions. For white matter tracts with primarily collinear fibers, T2a was found to depend on the angle of the tract relative to the main magnetic field, which is consistent with T2a being affected by magnetic field inhomogeneities arising from spatial differences in magnetic susceptibility. The T2e values were significantly smaller than the T2a values across white matter regions for several plausible choices of the intra-axonal diffusivity. The relaxation time for intra-axonal water in white matter can be determined in a straightforward manner by measuring the direction-averaged diffusion MRI signal with a large b-value for multiple TEs. In healthy brain, T2a is greater than T2e and varies considerably with anatomical region.

Microstructural Findings in White Matter Associated with Cannabis and Alcohol Use in Early-Phase Psychosis: A Diffusion Tensor Imaging and Relaxometry Study

Accumulating evidence suggests that brain white matter (WM) abnormalities may be central to the pathophysiology of psychotic disorders. In addition, there is evidence that cannabis use and alcohol use each is associated with WM abnormalities. However, there are very limited data on the effects of these substances on WM microstructure in patients with psychosis, especially for those at the early phase of illness. This project aimed to examine the impact of cannabis use and alcohol use on WM tissue in early-phase psychosis (EPP). WM was investigated in 21 patients with EPP using diffusion tensor imaging (DTI) and transverse relaxation time of tissue water (T2), with the primary outcomes being mean fractional anisotropy (FA) and T2. DTI analyses were performed at the full-brain level using tract-based spatial statistics with both DTI and T2 analysis done within a WM volume of interest (VOI) implicated in psychosis (containing the left superior longitudinal fasciculus). Our findings revealed that younger age of onset of regular alcohol use (more than one drink per week) was associated with lower FA values in the left thalamic radiation and left parahippocampal and left amygdalar WM. More frequent lifetime cannabis use was correlated with increased mean full-brain FA. There was no significant relationship found between FA and alcohol or cannabis use within the VOI. Relaxometry analysis revealed trend-level evidence of shortened T2 with later onset of regular alcohol use and with more frequent cannabis use. This study provides novel data demonstrating cortical and subcortical WM findings related to alcohol use in EPP and is the first to combine DTI and relaxometry, relating to this patient population.

Two-dimensional QT inversion of complex magnetic resonance tomography data

Surface nuclear magnetic resonance is a valuable technique that provides insight into the distribution of water content and relaxation time, thus revealing hydraulic properties in the subsurface. Recent research has introduced a new measurement layout that allows for time-efficient imaging of the 2D parameter distribution. Furthermore, for 1D investigations, it has been verified that complex data can provide improved resolution and depth penetration. In our research, we have developed an inverse modeling algorithm based on the QT-inversion scheme that uses the 2D complex magnetic resonance tomography data. We evaluate the uses and limitations of complex data for 2D investigations. By comparing resolution measures, we test this algorithm against state-of-the-art amplitude-based inverse modeling using resolution measures, a rigorous synthetic test, and a field example. Finally, we assess the impact of unknown conductivity and off-resonance excitation on the subsurface image and examined their limitations in field applications. We find that complex inversion is feasible in practice and provides superior results but demands precise knowledge of the true excitation frequency.

Amphiphilic Optimization Enables Polyaspartamides with Effective Kinetic Inhibition of Tetrahydrofuran Hydrate Formation: Structure–Property Relationships

Kinetic hydrate inhibitors (KHIs) are polymers that play a vital role in gas energy production, transport, and storage. A series of polyaspartamides based on l-aspartic acid were designed to serve as potential KHIs. Tuning the fine structures of the polyaspartamides can inhibit the tetrahydrofuran hydrate formation more effectively than classical KHIs, i.e., poly(N-vinylcaprolactam) (PVCap) and poly(N-vinylpyrrolidone) (PVP). When the hydrophobic side chain is longer, the polyaspartamide is more effective. For elucidation of the polymer structure–property relationships in the inhibition of the clathrate hydrate, the molecular-level interactions between the polyaspartamides and tetrahydrofuran hydrate were studied. Dynamics of water surrounding the polymers probed by NMR relaxometry demonstrate that the polyaspartamides can bind tightly with water molecules in the hydrate, resulting in faster transverse relaxation times of the nonfreezable water. This phenomenon can be interpreted by quantum chemical simul...

Gas-phase water: Features of hydrogen bonding deduced from far-infrared VRT spectra proving the cluster formation in vacuum

Far-infrared vibration–rotation-tunneling (VRT) spectra of gas-phase water reported previously have been interpreted in terms of polaronic exciton coupled model. An increase of the energy gap (Δν) between the neighboring absorption lines, which is observed in the spectrum within a pattern responsible for water cluster absorption, correlates with spin–orbit coupling parameter (β). Namely, experimental ratio (Δνi+1/Δνi) = 1.188996 ± 0.051361 has been found in fair agreement with β= 1.19100654 that implies the accumulation of difference between the absorption and emission energies. This correlation means the electrons coupled with protons establishing hydrogen bonds accumulate the energy difference. Relation deduced earlier for Boson peak frequency admitted to estimate fast Debye relaxation time for water that is found to be 0.183704 ps.

Rodent Cerebral Blood Volume (CBV) changes during hypercapnia observed using Magnetic Particle Imaging (MPI) detection

Magnetic Particle Imaging (MPI) is a rapidly developing imaging modality that directly measures and maps the concentration of injected superparamagnetic iron oxide nanoparticles (SPIOs). Since the agent does not cross the blood-brain barrier, cerebral SPIO concentration provides a direct probe of Cerebral Blood Volume (CBV). Here we provide an initial demonstration of the ability of MPI to detect functional CBV changes (fCBV) by monitoring SPIO concentration during hypercapnic manipulation in a rat model. As a tracer detection method, MPI offers a more direct probe of agent concentration and therefore fCBV than MRI measurements in which the agent is indirectly detected through perturbation of water relaxation time constants such as T2∗. We found that MPI detection could measure CBV changes during hypercapnia with high CNR (CNR = 50) and potentially with high temporal resolution. Although the detection process more closely resembles a tracer method, we also identify evidence of physiological noise in the MPI time-series, with higher time-series variance at higher concentration levels. Our findings suggest that CBV-based MPI can provide a detection modality for hemodynamic changes. Further investigation with tomographic imaging is needed to assess tomographic ability of the method and further study the presence of time-series fluctuations which scale with signal level similar to physiological noise in resting fMRI time-courses.

Synthesis, Stability and Relaxivity of TEEPO-Met: An Organic Radical as a Potential Tumour Targeting Contrast Agent for Magnetic Resonance Imaging.

Cancer is a widespread and life-threatening disease and its early-stage diagnosis is vital. One of the most effective, non-invasive tools in medical diagnostics is magnetic resonance imaging (MRI) with the aid of contrast agents. Contrast agents that are currently in clinical use contain metals, causing some restrictions in their use. Also, these contrast agents are mainly non-specific without any tissue targeting capabilities. Subsequently, the interest has notably increased in the research of organic, metal-free contrast agents. This study presents a new, stable organic radical, TEEPO-Met, where a radical moiety 2,2,6,6-tetraethylpiperidinoxide (TEEPO) is attached to an amino acid, methionine (Met), as a potentially tumour-targeting moiety. We describe the synthesis, stability assessment with electron paramagnetic resonance (EPR) spectroscopy and relaxation enhancement abilities by an in vitro nuclear magnetic resonance (NMR) and phantom MRI studies of TEEPO-Met. The new compound proved to be stable notably longer than the average imaging time in conditions mimicking a biological matrix. Also, it significantly reduced the relaxation times of water, making it a promising candidate as a novel tumour targeting contrast agent for MRI.

Variation of T2 relaxation times in pediatric brain tumors and their effect on metabolite quantification.

BackgroundMetabolite concentrations are fundamental biomarkers of disease and prognosis. Magnetic resonance spectroscopy (MRS) is a noninvasive method for measuring metabolite concentrations; however, quantitation is affected by T2 relaxation.PurposeTo estimate T2 relaxation times in pediatric brain tumors and assess how variation in T2 relaxation affects metabolite quantification.Study TypeRetrospective.PopulationTwenty‐seven pediatric brain tumor patients (n = 17 pilocytic astrocytoma and n = 10 medulloblastoma) and 24 age‐matched normal controls.Field Strength/SequenceShort‐ (30 msec) and long‐echo (135 msec) single‐voxel MRS acquired at 1.5T.AssessmentT2 relaxation times were estimated by fitting signal amplitudes at two echo times to a monoexponential decay function and were used to correct metabolite concentration estimates for relaxation effects.Statistical TestsOne‐way analysis of variance (ANOVA) on ranks were used to analyze the mean T2 relaxation times and metabolite concentrations for each tissue group and paired Mann–Whitney U‐tests were performed.ResultsThe mean T2 relaxation of water was measured as 181 msec, 123 msec, 90 msec, and 86 msec in pilocytic astrocytomas, medulloblastomas, basal ganglia, and white matter, respectively. The T2 of water was significantly longer in both tumor groups than normal brain (P < 0.001) and in pilocytic astrocytomas compared with medulloblastomas (P < 0.01). The choline T2 relaxation time was significantly longer in medulloblastomas compared with pilocytic astrocytomas (P < 0.05), while the T2 relaxation time of NAA was significantly shorter in pilocytic astrocytomas compared with normal brain (P < 0.001). Overall, the metabolite concentrations were underestimated by ∼22% when default T2 values were used compared with case‐specific T2 values at short echo time. The difference was reduced to 4% when individually measured water T2s were used.Data ConclusionDifferences exist in water and metabolite T2 relaxation times for pediatric brain tumors, which lead to significant underestimation of metabolite concentrations when using default water T2 relaxation times. Level of Evidence: 3 Technical Efficacy: Stage 2J. Magn. Reson. Imaging 2019;49:195–203.

Effect of multiple freeze-thaw cycles on the quality of instant sea cucumber: Emphatically on water status of by LF-NMR and MRI

Instant sea cucumber has become one popular product due to its convenience to eat, favourable taste and minimal loss of nutrients and bioactive components. However, there was rare information about the water dynamic of instant sea cucumber subjected to multiple freeze-thaw cycles. In this study, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance image (MRI) were employed to investigate the effect of freeze-thaw cycles on water status of instant sea cucumber. Four water populations corresponding to strongly bound water, weakly bound water, immobile water and free water were observed in instant sea cucumber. With the increase of freeze-thaw cycles, the transverse relaxation time of immobile and free water increased, while the peak area of free water decreased significantly. MRI enabled the visualization of water migration of instant sea cucumber during multiple freeze-thaw cycles. Multiple freeze-thaw cycles also led to significant changes of other quality properties including thawing loss, WHC, color parameters, texture and protein content, and enlarge the interspace between fiber network in microstructure. Good correlations between T22, A22, A23 and thaw loss, WHC, L*, hardness and collagen content (0.873 ≤ r ≤ 0.958) revealed LF-NMR may be an effective real-time monitoring method of these physicochemical parameters as a non-destructive technique.

Graphene Oxide-Iron Oxide Nanoconjugates for Drug Transport, Biosensing and Bimodal Fluorescence/Magnetic Resonance Imaging

Due to its remarkable properties, graphene has become a basis of many novel microelectronic devices. However its functional derivatives including graphene oxide (GO) can be mass-produced at lower costs and retain many properties of graphene in addition being water soluble. GO also exhibits fluorescence in the visible/near-IR suitable for applications in optoelectronics and biomedicine. The most novel biomedical applications of GO include, sensing, molecular imaging in visible/near-IR and drug delivery. In all these applications GO was mostly proposed as an agent for in-vitro or ex-vivo imaging due to its emission in visible or near-IR. In this work we combine GO with superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) to provide the unique capacity of multimodal imaging and magnetic targeted drug delivery. Fe3O4 NPs are biocompatible and have been used as biosensing, magnetic assisted drug delivery system and also a magnetic resonance contrast agent for MRI. Additionally, these NPs can be attracted by a magnet allowing for targeting of the attached therapeutics via the magnetic field to specific organ and/or cancer tumor. In this work, we fabricate nanoconjugates of GO- Fe3O4 for combining GO fluorescence, sensing and drug delivery properties with magnetic targeting and a possibility of MRI imaging provided by Fe3O4. GO flakes were processed to have diameter mean size of 260 nm optimal for cellular internalization and conjugated to Fe3O4 NPs. For the specific application of magnetic resonance imaging, the quality of an MRI contrast agent is often evaluated by the relaxivity parameters r1 or r2, which describe the ability of a contrast agent to shorten the T1 or T2 relaxation time of water. GO-Fe3O4 showed suitable for MRI imaging relaxivity values (longitudinal r1 and transvers r2 in water at 37°C), of r1=6.6 mM-1s-1 and r2=71.1 mM-1s-1. In fact, these values are better than those for single Fe3O4 NPs: the conjugated samples showed relaxivity ratio r2/r1>2, placing them in the category of negative contrast agent. The cytotoxicity of GO-Fe3O4 established via MTT assay in HeLa cells showed over 80% viability at the imaging concentrations mimicking that of GO. Cellular uptake and imaging studies show stable internalization and localized emission inside the cells. Additionally this system provides an efficient route to pH sensing of cellular environment as spectra of in GO-Fe3O4 are highly dependent on the pH of the media. This allows to assed the presence of acidic cancerous environments for cancer therapy and detection. As a result, we propose that this new multifunctional GO-Fe3O4 composite can be used as a magnetic targeted drug delivery system, as well as biosensing and bimodal (MRI and fluorescence) imaging agent.

F231. Microstructural Changes in White Matter Associated With Alcohol Use in Early Phase Psychosis: A Diffusion Tensor Imaging (DTI) and Relaxometry Study

Accumulating evidence suggests that brain white matter (WM) abnormalities may be central to the pathophysiology of psychotic disorders. Additionally, cannabis use and alcohol use are each associated with WM abnormalities, however there is limited data on these substances effects on WM microstructure in psychosis, especially early phase psychosis (EPP). This study examined the impact of cannabis use and alcohol use in WM in EPP (N=21) using diffusion tensor imaging (DTI) and transverse relaxation time of tissue water (T2), with the primary outcomes being mean fractional anisotropy (FA) and T2.

Practical considerations for small receive coils in surface NMR

The development of multichannel instrumentation was a significant step forward for surface nuclear magnetic resonance (NMR). Multichannel instruments allow data to be recorded on multiple receivers simultaneously, thus facilitating the exploitation of Wiener filtering techniques that provide significant signal-to-noise increases and allow two- and three-dimensional images of the subsurface properties to be produced. When working in challenging environments (e.g. forested/brushy terrain), difficult noise conditions, or when using complicated survey designs it can become quite cumbersome to deploy multiple coils, which often require substantial lengths of cable to be deployed. As such, it would be advantageous if the dimensions of typical receive coils could be greatly reduced from the current standards (~25–100 m). The use of small receive coils would lead to more rapid survey deployment and may advance the utility of methods requiring multiple receivers. The objectives of this work are two-fold. The first aims to quantify limits on the feasible dimensions of small receive coils in surface NMR, aiming to provide an estimate of the minimum effective area of a functional surface NMR receiver. The second aims to demonstrate that the use of multiple additional small receive coils (when used in conjunction with the standard large coincident transmit/receive coil) can help to improve the resolution of estimated water content and relaxation time depth profiles. Synthetic results are presented to quantify lower effective area limits and to demonstrate potential resolution improvements provided by small receivers. The feasibility of a small receiver (400 m2 and 200 m2) is demonstrated in a field setting.

Measurement of water mobility and distribution in vacuum microwave-dried barley grass using Low-Field-NMR

ABSTRACTWater mobility is an indicator of product quality of dried barley grass. To investigate the water mobility and distribution of dried barley grass, microwave vacuum drying (MVD) was conducted at different powers (100, 200, and 300 W) until water content of dried product reached 3% (w.b). Water profile was measured by Low-field nuclear magnetic resonance (LF-NMR), including free water, surface water (molecular attraction), and immobilized water (attraction of polar clusters). Drying time at 100, 200, and 300 W presented about 90, 70, and 50 min, respectively. Changes of free water and immobilized water and surface water were affected differently by variant microwave power. After drying for 50 min, the mobility of water is reduced greatly and proportion of surface water predominated. Transverse relaxation time for free water and immobilized water decreased significantly (P ≤ 0.05) from start and then leveled off. Predomination of surface water and immobilized water assures the safety and quality of products of dried barley grass. Low-field nuclear magnetic resonance (LF-NMR) is outstanding to measure the water state of barley grass during MVD.

LF-NMR online detection of water dynamics in apple cubes during microwave vacuum drying

ABSTRACTIn this study, changes in various states of water in apple cubes were assessed using low-field nuclear magnetic resonance (LF-NMR) during microwave vacuum drying. Apple cubes were dried at different microwave power levels (100, 150, and 200 W). Indicators including moisture content and water activity were measured. The Carr–Purcell–Meiboom–Gill (CPMG) sequence was used to measure transverse relaxation times (T2). The results showed that three water fractions with different T2 relaxation times (around 11, 126, and 1335 ms) were detected in fresh apples, which corresponded to different cell compartments. The transverse relaxation time of bulk water (T23) and the signal per mass of the bulk water (A23/g) decreased significantly with increasing drying time at different microwave power levels. The signal per mass of the total water (ATotal/g) had significant correlation with the total moisture content (R2 = 0.9919). Furthermore, good correlation (R2 = 0.9799) between water activity and NMR parameters based on partial least square regression model were observed. This research revealed that LF-NMR spectroscopy, a nondestructive technique, can detect the changes of water in different populations in the matrix.

Probing collective Motions of Proteins and Hydration Dynamics in Aqueous Solutions by a Wide Range Dielectric Spectroscopy

Conformational dynamics of proteins affect how biological molecules exert their function and regulate their biological processes. Studying the dynamics of proteins and their hydration allows us to analyze their functions in aqueous solutions. However, the strong absorption of water makes tracking collective mode changes challenging. Thus, we have developed a very sensitive dielectric megahertz-to-terahertz frequency-domain spectroscopy system to probe the hydration shells as well as large-scale dynamics of these biomolecules. Using this system, we explore the real and imaginary dielectric response of solvated biomolecules over a range of 50 MHz to 2 THz. We have chosen several proteins to provide a model system including bovine serum albumin (BSA), lysozyme, cytochome_c, and myoglobin proteins. We have compared the dynamics of proteins as well as their hydration water. We have deduced the dynamics and the hydration water of these proteins by comparing their real and imaginary dielectric response and hydration water relaxation times. Comparing these assets of various proteins in different classes helps us shed light on the macromolecular dynamics in a biologically relevant water environment.

Characteristics of surface nuclear magnetic off-resonance signal and complex envelope inversion

As a new groundwater exploration method, noninvasive surface nuclear magnetic resonance (SNMR) has the benefits of direct, quantitative and uniqueness estimation of water content and relaxation time (T2*) in the near surface groundwater exploration. In practice, the earth magnetic field is difficult to be determined accurately, due to its inhomogeneity, time-varying and susceptible to ambient noise, which results in off-resonance excitation and serious decrease in accuracy of the inversion result. In this paper, based on the model of surface nuclear magnetic off-resonance (SNMOR) and the expression for the kernel function, the influences of the frequency offset on the amplitude and phase of the free induced decay (FID) signal are discussed, and a complex envelop inversion (CEI) based on automatic matching system phase and involving both the real part and imaginary part of the signal is applied. By comparing the synthetic signals generated from the SNMR and SNMOR models, it can be concluded that the phase of the FID signal significantly changes with the increase of the frequency offset, and the amplitude of the signal can be increased by 65.9% for the synthetic model in this paper. Thus when the frequency offset is greater than 2 Hz, the distribution of water content and T2* from the inversion results using the SNMR kernel will have a serious deviation from the actual model. However, using the SNMOR kernel based on the frequency offset, the inversion results are more accurate, and the maximum error of the water content and T2* are 4.2% and 39.3 ms, respectively. Moreover, synthetic data with different noise levels are inverted by the CEI method and conventional amplitude envelop inversion method (or QTI). The results show CEI obtain better performances in stability and reliability at a high noise level. Finally, a field measurement of SNMOR is conducted in Taipingchi Reservoir near Changchun City, China. The off-resonance FID signals are obviously observed by utilizing the JLMRS instrument and can be used to estimate the frequency offset. The characteristics of the FID signal with the frequency offset confirm the correctness of the SNMOR model. And the inversion result of field data using SNMOR kernel show that the distribution of water content and T2* are consistent with the known geological data from the drillings and other geophysical methods, which is much better than that using the SNMR kernel or conventional amplitude envelop inversion method. Therefore, the validities and accuracies of the SNMOR model and CEI method proposed in this paper are verified, which provides a new idea and technique for groundwater exploration in the near surface.