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• Placental volume and transverse relaxation time (T2*) are predictors of small for gestational age (SGA). • In the multi-variate model, placental T2* was the only independent predictor of SGA. • Placental magnetic resonance imaging may improve the antenatal detection of SGA. Placental magnetic resonance imaging (MRI) may be a valuable tool in the prediction of small for gestational age (SGA) at birth. MRI provides reliable estimates of placental volume and thickness. In addition, placental transverse relaxation time (T2*) may be directly related to placental function. This study aimed to explore and compare the predictive performance of three placental MRI parameters – volume, thickness and T2* – in relation to SGA at birth. A mixed cohort of 85 pregnancies was retrieved from the placental MRI database at the study hospital. MRI was performed in a 1.5 T system at gestational weeks 15–41. In normal birthweight (BW) pregnancies [BW > –22 % of expected for gestational age (GA)], the correlation between each of the MRI parameters and GA was investigated by linear regression. The prediction of SGA was investigated by logistic regression analysis adjusted for GA at MRI. In normal BW pregnancies, a significant linear correlation was found between GA and each of the MRI parameters. Univariate analysis demonstrated that placental volume [odds ratio (OR) 0.97, p = 0.001] and placental T2* (OR 0.79, p = 0.003), but not placental thickness (OR 0.92, p = 0.862) were significant predictors of SGA. A multi-variate model including all three MRI parameters found that placental T2* was the only independent predictor of SGA (OR 0.81, p = 0.04). Among the MRI parameters investigated in this study, placental T2* was the only independent predictor of SGA in a multi-variate model. This finding underlines the strong position of T2*-weighted placental MRI in the prediction of SGA. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the time-course of the physical properties of the psoas major muscle (PM) before and after exercise using magnetic resonance elastography (MRE). Muscle stiffness is one of the important properties associated with muscle function. However, there was no research on the stiffness of the PM after exercise. In this study, we investigated time-course changes of the shear modulus of the PM after exercise. Furthermore, T2 values and apparent diffusion coefficient (ADC), as the additional information associated with muscular physical properties, were also measured simultaneously. Healthy young male volunteers were recruited in this study (n = 9) and they were required to perform a hand-to-knee isometric and unilateral exercise (left side). At each time-point before and after exercise, a set of 3 types of MR scans to measure multiple physical properties of the PM [shear modulus (MRE), T2 values, and ADC] were repeatedly taken. On day 1, a single set MR scan was taken before exercise (pre-exercise MR scan), and 6 sets MR scans were taken (5.5 to 38.0 min after exercise). After about 10-min rest (46.0 to 56.0 min after exercise), 4 sets MR scans were taken (57.5 to 77.0 min after exercise). About 10-min rest was taken again (85.0–95.0 min after exercise), 4 sets MR scans were taken (96.5 to 116.0 min after exercise). On days 2 and 7, a single set MR scan (MRE, T2 value, and ADC) was taken on each experimental day. The data were analyzed as relative changes (%) of the given parameters to the pre-exercise values. The results indicated significant decreases in PM shear modulus up to about 30 min after exercise. Then, it gradually increased and showed significant increases at about 100 min after exercise compared to that before exercise. T2 values and ADC showed significant increases up to about 65 min after exercise compared to those before exercise, and then returned to the pre-exercise values. On days 2 and 7, all values showed no significant changes compared to the pre-exercise values. This study is the first to report the time-course of the physical properties of the PM after exercise. [ABSTRACT FROM AUTHOR]

Single-sided magnetic resonance (SSMR) offers advantages of portability and noninvasive measurement for water detection, with significant potential applications in groundwater exploration, petroleum well logging, and soil moisture monitoring. However, the inherent highly inhomogeneous static magnetic field and radiofrequency (RF) field in SSMR necessitate the utilization of the Carr–Purcell–Meiboom–Gill (CPMG) sequence measurement scheme. To accelerate forward modeling during pulse excitation, we introduce a Geometric Analysis Method (GAM) and assess T 2 error using its primary parameters. The GAM involves applying spatial geometric rotations on the magnetization vector, leading to an analytical solution to the Bloch equation that disregards relaxation effects. Compared with the rotation matrix (RM) method, the GAM demonstrates high accuracy and reduces computational time by approximately 20.9%. By analyzing the primary parameters governing the magnetization vector in the analytical formula, we evaluated their impact on the transverse relaxation time (T 2) obtained through fitting the SE signal. Ultimately, the forward modeling results of the CPMG sequence within the region of interest (ROI) of a single-sided Halbach magnet array are validated. The T 2 fitting error increases as the primary parameters deviate from the ideal values, highlighting their significant role in the T 2 fitting results. This study provides a theoretical foundation for optimizing the design of SSMR magnets and RF coils. • Geometric analytical method (GAM) is proposed to solve the Bloch equation. • Compared with the rotation matrix (RM) method, the GAM demonstrates high accuracy and reduces computational time by approximately 20.9%. • The primary parameters in GAM can be used to evaluate the T 2 fitting error. • This research provides a theoretical basis for optimizing the design of SSMR magnets and RF coils. [ABSTRACT FROM AUTHOR]

• A paramagnetic Cu2+-induced magnetic resonance tuning (MRET) strategy is proposed. • A Cu–M-MRS immunosensor was constructed for detection of chlorpyrifos and Salmonella. • Fe 3 O 4 @PDA-Ab 2 was used for signal conversion by regulating the amount of Cu2+ ions. • The LOD for chlorpyrifos and Salmonella are 0.05 ng/mL and 50 CFU/mL, respectively. Magnetic relaxation switching (MRS) biosensors have been recognized as useful analytical tools for a range of targets; however, traditional MRS biosensors are limited by the "prozone effect", resulting in a narrow linear range and low sensitivity. Herein, we proposed a paramagnetic Cu2+-induced magnetic resonance tuning (MRET) strategy, based on which Cu2+ ions and magnetic nanoparticles (MNPs) were adopted to construct a Cu–MNP-mediated MRS (Cu–M-MRS) immunosensor with Cu2+ ions acting as a quencher and MNPs as an enhancer. An Fe 3 O 4 @polydopamine-secondary antibody conjugate was prepared and used to correlate the amount of Cu2+ ions to the target concentration through an immunoassay. Based on the immunoreaction, the Cu–M-MRS immunosensor enabled the sensitive detection of chlorpyrifos (0.05 ng/mL, a 77-fold enhancement in sensitivity compared with the traditional MRS immunosensor) and Salmonella (50 CFU/mL). The proposed MRET strategy effectively improved the sensitivity and accuracy of the MRS immunosensor, offering a promising and versatile platform for food safety detection. [ABSTRACT FROM AUTHOR]

The associations of 4 proteins—AK4, ITPK1, HSPB2, and IGFBP5—with cognitive function in older adults were largely unexplained by known brain pathologies. We examined the extent to which individual protein associations with cognitive decline were attributable to microstructural changes in the brain. This study included 521 participants (mean age 90.3, 65.9–108.3) with the postmortem reciprocal of transverse relaxation time (R 2) magnetic resonance image. All participants came from one of the 2 ongoing longitudinal cohorts of aging and dementia, the Religious Orders Study and Rush Memory and Aging Project. Higher abundance of AK4, HSPB2, and IGFBP5 was associated with faster cognitive decline and mediated through lower postmortem R 2 in the frontal and temporal white matter regions. In contrast, higher abundance of ITPK1 was associated with slower cognitive decline and mediated through higher postmortem R 2 in the frontal and temporal white matter regions. The associations of 4 proteins—AK4, ITPK1, IGFBP5, and HSPB2—with cognition in late life were explained via microstructural changes in the brain. • Microstructural change in the brain mediates relation of 4 proteins to cognition. • AK4, HSPB2, and IGFBP5 associated with faster cognitive decline via damaged white matter. • ITPK1 associated with slower cognitive decline via healthy state of white matter. [ABSTRACT FROM AUTHOR]

Abstract Identification of pay zones is as a challenging topic in the reservoir characterization. Various methods have been employed to tackle this prominent task. Well logs are one of the most useful means for identifying pay zones, chiefly resistivity logs. However, resistivity measurements in some complex environments such as mixed lithology reservoirs, low resistivity and low contrast pay zones may fail to unveil productive zones. As an essentially lithology-independent tool, nuclear magnetic resonance (NMR) log may be the only approach to deal with detecting such subtleties. Using wavelet analysis technique and the NMR log data, this paper was aimed at identifying hydrocarbon bearing zones in two carbonate reservoirs. Discrete wavelet transform (DWT) was applied to the spin echo train at each depth to extract transverse relaxation time ( T 2 ). By comparing the generated T 2 log and resistivity log, a striking similarity was found between them. The T 2 log manifested strong correlation with porosity log. Therefore, the DWT was repeatedly applied to the T 2 log so as to remove the correlation. Various wavelets were adopted to remove the effect of porosity from the T 2 log, leading to achieve pore fluid transverse relaxation time, referred to as T 2 f . Scrutinizing the T 2 f log demonstrated that this log is not only highly functional in detecting productive zones but also highly capable of highlighting the subtle changes of pay zones. Consequently, the T 2 f log revealed the latent pay zones unseen by resistivity log. Highlights • This paper was aimed to identify pay zones using wavelet analysis on NMR log data. • The DWT was initially utilized to denoise the CPMG spin echo train at each depth. • Transverse relaxation time was obtained from the smoothed CPMG sequence. • The DWT was again conducted to remove the information of porosity. • Pore fluid transverse relaxation time led to distinguishing pay zones. [ABSTRACT FROM AUTHOR]

Abstract Based on the low hydration heat requirement of cement slurry system used in natural gas hydrate formation and the effective utilization of industrial waste materials, the fly ash and slag were introduced into ordinary Portland cement to prepare a low hydration heat cement slurry system. During this study, the influences of fly ash and slag on the heat evaluation of cement slurry system were investigated by temperature profiles and hydration heat, which were tested by using a developed semi-adiabatic test equipment. Currently, the temperature profiles of cement slurry system were studied by the initial temperature (T i), temperature rise (T r), maximum temperature (T m), and the hydration time (t m) corresponding to the maximum temperature, respectively. Moreover, the investigations of the influences of fly ash and slag on the strength property of cement stone were investigated. Then, a novel low hydration heat cement slurry system CFS 1-1 used in natural gas hydrate formation was developed by the mass ratio of 2:1:1 (cement: fly ash: slag). Simultaneously, the initial hydration process of CFS 1-1 was investigated by low field NMR, the rheological and thickening properties of CFS 1-1 were also studied. Besides, some other application performances, such as density, fluidity, stability and consistency, were also studied. As a result, it was found that the application performances of CFS 1-1 meet the cementing requirement of hydrate formation. In addition, the effective and reasonable utilization of industrial waste materials were also realized during this study. Highlights • Hydration heat evaluation was controlled by fly ash and slag. • Semi-adiabatic test equipment was developed. • A novel low hydration heat cement slurry was developed. • A new possibility for cementing of hydrate formation was provided. • The effective utilization of industrial waste materials is also realized. [ABSTRACT FROM AUTHOR]

Emulsions are thermodynamically unstable systems formed through blending of two immiscible fluids. Recent studies have shown that High Hydrostatic Pressure (HHP) can initiate or accelerate lipid crystallization in emulsions. In this study, the effect of HHP on lipid crystallization was examined. Emulsion samples were prepared with palm stearin (PS) as the oil phase and sodium caseinate (SC) as the emulsifier and they were pressurized at 100 and 500 MPa at 10, 20 and 40 °C for 15 min. In order to determine the crystal structure of the emulsions, differential scanning calorimeter (DSC) was used and the change in the crystal morphology during 28 day-storage at 4 °C was observed. Nuclear Magnetic Resonance Relaxometry (NMR) experiments were also conducted and transverse relaxation time (T 2 ) and self-diffusion coefficient (SDC) values showed a trend to follow polymorphic changes of lipid crystals. Results showed that pressure and storage time both had significant effects (p < 0.05) on the crystal structures of emulsions. [ABSTRACT FROM AUTHOR]

The transverse relaxation time of noble-gas atoms in nuclear-magnetic-resonance gyroscopes is a very important indicator for measuring the gyroscope’s performance. In this paper, the optimized free-induction-decay method, together with fitting-ratio method and magnetic-resonance-broadening method in the rotating coordinate system, is analyzed for the first time, in order to accurately measure the transverse relaxation time. An experimental device was designed, and the transverse-relaxation-time measurements were carried out by using these three methods under specific conditions. The advantages of these three methods are analyzed by comparison of experimental process and experimental results. The influence of pump-light intensity on the transverse relaxation time of noble-gas atoms is further studied on this basis, and verified through experiments. [ABSTRACT FROM AUTHOR]

Hydroxypropyl methylcellulose (HPMC) belongs to the cellulose ether family that has hydroxyl groups substituted by hydrophobic methyl groups (DS) and hydrophilic hydroxypropyl groups (MS). Herein, the interactions between water molecules and cryogels prepared with HPMC in the presence and absence of a linear nonionic surfactant, as well as CaO 2 microparticles, which react with water producing O 2 , were systematically investigated by sorption experiments and Time-Domain Nuclear Magnetic Resonance. Regardless of the DS and MS, most water molecules presented transverse relaxation time t2 typical of intermediate water and a small population of more tightly bound water. HPMC cryogels with the highest DS of 1.9 presented the slowest swelling rate of 0.519 ± 0.053 g water /(g.s) and the highest contact angle values 85.250o ± 0.004o, providing the best conditions for a slow reaction between CaO 2 and water. The presence of surfactant favored hydrophobic interactions that allowed the polar head of the surfactant to be exposed to the medium, resulting in a higher swelling rate and lower contact angle values. The HPMC with the highest MS presented the fastest swelling rate and the lowest contact angle. These findings are relevant for the formulations and reactions, where tuning the swelling kinetics is crucial for the final application. [Display omitted] • HPMC cryogels with the highest DS had the lowest wettability and swelling rate. • HPMC hydrogels presented mostly intermediate water and a small fraction of bound water. • Surfactant affected moderately the wettability of HPMC cryogels. • The incorporation of CaO 2 into HPMC cryogels retards its reaction with water. [ABSTRACT FROM AUTHOR]

Food structure affects the breakdown kinetics of food. This has been extensively studied via in vitro digestion models. However, these in vitro findings need to be verified in vivo. Previously, we found that MRI parameters (T 1 and T 2 relaxation times) can serve as markers of protein digestion. Here, we assessed the effect of food hardness and protein content on gastric emptying as well as the application of these MRI parameters to monitor in vivo gastric digestion of solid foods. In a randomized cross-over trial, 18 healthy males (age: 27 ± 5 y; BMI 23 ± 1 kg/m2) ingested three gels: a soft gel with low protein content (Soft-LP), a hard gel with low protein content (Hard-LP), and a hard gel with high protein content (Hard-HP). Before and every 10 min after ingestion till 85 min, abdominal MRI scans were obtained to determine the gastric content volume and T 1 and T 2 of the gastric content. The decrease in gastric content volume differed among gels: Hard-HP < Hard-LP < Soft-LP. For all gels, mean T 1 and T 2 of the measured stomach content decreased directly after ingestion and then after 15 min gradually increased with Hard-HP < Hard-LP < Soft-LP. In conclusion, high protein content and high hardness slowed gastric emptying down. In addition, we show that T 1 and T 2 measurements provide extra information on the dilution and digestion of solid foods in the stomach. This underpins the potential of MRI to provide insights into in vivo protein digestion and link in vitro and in vivo digestion research. [Display omitted] • We studied gastric digestion of protein gels differing in protein content and hardness in a human trial. • High protein content and high hardness reduce gastric emptying. • In vivo MRI T 1 and T 2 measurements can provide extra information on the dilution and digestion. • These in vivo data can serve as input data for tuning and validating in vitro and in silico models. [ABSTRACT FROM AUTHOR]

In this study, we aimed to elucidate the characteristics of water mobility and distribution in soybean antioxidant peptide powders (SAPPs) using low-field nuclear magnetic resonance (LF-NMR). SAPPs of three different molecular weights (MWs) were exposed to a room temperature environment with a relative humidity of 45%, and the dynamics of water mobility and distribution were monitored by LF-NMR. Results revealed that there were four transverse relaxation time fractions in SAPPs. The major (over 90%) fraction was bound water, and the distribution of water in samples with different MWs was different. The moisture absorption capacity of SAPPs with MWs of less than 1 kDa was the strongest, and all T 2 fractions/water population contents in SAPPs with MWs of 1–3 kDa were the lowest. This study provided an effective real-time monitoring method for water mobility and distribution in SAPPs and may have applications for promoting peptides quality assurance. [ABSTRACT FROM AUTHOR]

Single-sided NMR devices, like NMR MOUSE (MObile Universal Surface Explorer), are designed to allow NMR surface measurements to be conducted on arbitrarily large samples, and are therefore valuable tools to evaluate non-invasively moisture content “inside” a planar object. In this work, we aim to perform “in situ” studies of moisture transport in building materials during drying experiments with NMR MOUSE. The local moisture content was monitored over time and mapped over sample thickness with a depth resolution of 0.5 mm and a maximum penetration depth of 15 mm. In addition, NMR MOUSE allows measuring transverse relaxation time T 2 . Experimental results show that moisture content is homogeneously distributed over the thickness, which indicates that moisture is transferred through capillary processes. Furthermore, transverse relaxation time distribution measurements revealed that the drainage of pore water occurs sequentially from larger pores to smaller pores. [ABSTRACT FROM AUTHOR]

Rationale and Objectives The objectives of this research study were to determine the magic-angle effect on different subregions of in vivo human femoral cartilage through the quantitative assessment of the effect of static magnetic field orientation ( B 0 ) on transverse (T 2 ) relaxation time at 3.0 T. Materials and Methods Healthy volunteers ( n = 5; mean age, 36.4 years) and clinical patients ( n = 5; mean age, 64 years) with early osteoarthritis (OA) were scanned at 3.0-T magnetic resonance using an 8-channel phased-array knee coil (transmit-receive). Results The T 2 maps revealed significantly greater values in anterior than in posterior regions. When the cartilage regions were oriented at 55° to B 0 (magic angle), the longest T 2 values were detected in comparison with the neighboring regions oriented 90° and 180° (0°) to B 0 . The subregions oriented 180° (0°) to B 0 showed the lowest T 2 values. Conclusions The differences in T 2 values of different subregions suggest that magic-angle effect needs to be considered when interpreting cartilage abnormalities in OA patients. [ABSTRACT FROM AUTHOR]

Abstract: Duchenne muscular dystrophy (DMD) is characterized by an increased muscle damage and progressive replacement of muscle by noncontractile tissue. Both of these pathological changes can lengthen the MRI transverse proton relaxation time (T2). The current study measured longitudinal changes in T2 and its distribution in the lower leg of 16 boys with DMD (5–13years, 15 ambulatory) and 15 healthy controls (5–13years). These muscles were chosen to allow extended longitudinal monitoring, due to their slow progression compared with proximal muscles in DMD. In the soleus muscle of boys with DMD, T2 and the percentage of pixels with an elevated T2 (⩾2SD above control mean T2) increased significantly over 1year and 2years, while the width of the T2 histogram increased over 2years. Changes in soleus T2 variables were significantly greater in 9–13years old compared with 5–8years old boys with DMD. Significant correlations between the change in all soleus T2 variables over 2years and the change in functional measures over 2years were found. MRI measurement of muscle T2 in boys with DMD is sensitive to disease progression and shows promise as a clinical outcome measure. [Copyright &y& Elsevier]

• Physical improvement of steel slag cement by HEMC is confirmed and analyzed. • Ultra-fine grinding is able to improve reactivity of steel slag remarkably. • Calcium ion complexation enhanced the dissolution of SCMs. • HEMC leads to a new peak in T 2 pattern of 1H NMR. The applications of steel slag (SS) in the cement industry provide a sustainable solution both for construction materials and industrial solid wastes, but the problem of easily bleeding presents a threat to its later performance and utilization efficiency. This work was designed to improve the water retention of SS blended cement by using hydroxyethyl methyl cellulose (HEMC) and evaluate the physio-chemical properties of the modified SS cement. The interaction mechanism between HEMC and SS blended cement was explored via calorimetry, acoustic and electroacoustic spectrometer, low-field NMR relaxometry, XRD, TG-DSC, as well as fluorescent microscopy. Results show that the water retention of SS blended cement mortar is improved both by ultra-fine grinding and incorporating HEMC, while the water retention rates are prominently increased from 84.87% to 94.35% by 0.1% HEMC. Ultra-fine grinding is able to activate SS and improve water retention ability more efficient compared with the application of HEMC. HEMC does not modify the amount of hydration heat but postpones the occurrence of the exothermic peak. A sudden increase in zeta potential demonstrates the Ca2+-adsorption on surfaces of SCM and cement particles. An additional peak commences on the 1H NMR spectrum of HEMC incorporated cement paste, which reflects the water adsorbed by HEMC, starting to submerge after 500 min via the desorption of water. HEMC affects the SS blended mortar via adsorbing on particles in the paste, capturing water and Ca2+ around it, thus improving the water retention and retarding the hydrate-polymerization. [ABSTRACT FROM AUTHOR]

Traditional magnetic relaxation switching (MRS) biosensors suffer from poor sensitivity and unsatisfactory stability. In this study, a polydopamine (PDA) nanoparticles (NPs)-Cu2+ chelate complex mediated signal conversion system and a Cu+-catalyzed click chemistry triggered magnetic signal amplification system were evaluated and dynamically integrated into an MRS biosensor. Owing to abundant functional groups and a large surface area, PDA NPs enabled the absorption of a large amount of Cu2+ ions by chelation. The residual Cu2+ ions can be reduced with sodium ascorbate to Cu+, which could initiate the click reaction between azide-functionalized magnetic NPs (MNPs) and alkyne-functionalized MNPs that resulted in the production of aggregated nanoclusters. The transverse relaxation time (T 2) depends on the degree of aggregation of MNPs; T 2 is expressed as the magnetic signal readout. In addition, PDA NPs can be easily conjugated with antibodies by mixing, thus providing a straightforward bridge that integrates the immunoassay and magnetic signal readout. Combined with the high capacity of PDA NPs for chelating Cu2+ and high efficiency of click reaction for changing the T 2 signals, the PDA-MRS biosensor enables the detection of chlorpyrifos with a limit of detection of 0.084 ng/mL, providing 22-fold enhancement than traditional enzyme-linked immunosorbent assay (1.86 ng/mL). This demonstrates its great potential for the detection of hazardous chemical molecules in a complex sample matrix. • PDA NP mediated click chemistry is an efficient magnetic relaxation sensing strategy. • PDA NP can absorb Cu2+ ions by chelation and can be covalently attached to antibody. • CuCC-triggered aggregation of MNPs is used to generate and amplify magnetic signals. • The magnetic biosensor detects chlorpyrifos with high sensitivity and good stability. [ABSTRACT FROM AUTHOR]

Transverse relaxation time (T2)-weighted images and T2 maps of white salted noodles (WSN) were investigated by magnetic resonance imaging technique. T2-weighted images and T2 maps clearly showed the differences in water status between noodles. The migration of moisture from surface regions to central regions of boiled WSN at different migration rates were investigated during storage. The distribution of T2 values changed differently depending on the cooking and storage times. The small differences in T2 values between surface region and central region of noodles cooked for 5 and 15 min were attributed to the limited water absorption during short cooking time, which resulted in high firmness. The changes in starch granules morphology observed under scanning electron microscope and the increase of noodle firmness measured by texture analyzer were significantly affected by the water status in noodles. The water status can be controlled by the cooking time. [Copyright &y& Elsevier]

Gels consist of crosslinked polymer network swollen in solvent. The network of flexible long-chain molecules traps the liquid medium they are immersed in. Some gels undergo abrupt volume change, a phase transition process, by swelling-shrinking in response to external stimuli changes in solvent composition, temperature, pH, electric field, etc. We report that during volume phase transition changes of NMR longitudinal relaxation time T1, NMR transverse relaxation time T2, and diffusion coefficient D of the PMMA gel, and D of the NIPA gel. We describe how the gels were synthesized and the reason of using the snapshot FLASH imaging sequence to measure T1, T2, and D. Since T1, T2 and D maps have identical field of view and data are extracted from identical areas from their respective maps, these values can be correlated quantitatively on a pixel-by-pixel basis. Thus a complete set of NMR parameters is measured in-situ: the gels are in their natural state, immersed in the liquid, during the phase transition. The results of spectroscopic method agree with that of snapshot FLASH imaging method. For the PMMA gel T1, T2 and D decrease when gels undergo volume phase transition between deuterated acetone concentration of 30% and 40%. At its contracted state, T1 is reduced to a little less than one order of magnitude, T2 over two orders of magnitude, and D over one order of magnitude, smaller from values of PMMA gel at the swollen state. At an elevated temperature of 54°C the thermosensitive NIPA gel is at a contracted state, with its D reduced to almost one order of magnitude smaller from that of the swollen NIPA at room temperature. [Copyright &y& Elsevier]

An accurate measurement of the transverse relaxation time T2, and the histogram of T2 in the brain parenchyma can be accomplished in vivo using a multi-echo magnetic resonance imaging sequence. An estimate of the error in the T2 measurement is derived using copper sulfate doped water phantoms. Correction factors are calculated and applied to the signal intensity of each voxel prior to the in vivo T2 evaluation. These corrected T2 are in good agreement with the theoretical values calculated from copper sulfate concentrations. This technique is then applied to calculate T2 histograms of the brain. The population studied was composed of normal volunteers and multiple sclerosis patients. The corrected T2 histogram method discriminates the normal control population from the MS population, and also discriminates between relapsing-remitting patients and primary progressive or secondary progressive patients. Moreover using this approach we are able to detect in MS patients a global shift of the T2 of the white mater toward higher values. The results of this study showed that the method is easy to implement and may be used to characterize MS pathology. [Copyright &y& Elsevier]

Maintaining the accuracy of well-logging interpretations in igneous reservoirs has long been a difficult problem. The igneous gas reservoirs in eastern China are important exploration targets at the present time. It has been found that, when compared with sedimentary rock reservoirs, the properties of igneous rock change faster with depth, and the reservoir spaces tend to be more complex. In addition, the porosity and permeability are lower, making the evaluations of water saturation more challenging. Generally speaking, the Archie Equation parameters can be obtained through a large number of laboratory core measurements, and then applied to the logging interpretations of water saturation. However, the longitudinal heterogeneity of reservoirs is neglected by fixed parameters which are referred to as "static parameters". In the current research investigation, in order to improve the accuracy of the logging interpretations, a method of segmentation characterization was used to invert the Archie's Equation parameters from NMR logging data, based on the relationships between the transverse relaxation times (T 2) and the resistivity indexes (I). Subsequently, the dynamic Archie parameters which changed with depth were obtained using the aforementioned method, which had not only considered the longitudinal heterogeneity of the reservoirs, but also provided a new interpretation method for the water saturation of igneous reservoirs. In addition, this study also analyzed the relationships between the key parameters and pore structure parameters in the designed model. It was found that the data distributions of igneous rock and sedimentary rock had displayed opposite trends. Therefore, the results of this study confirmed that the conductivity of igneous rock is affected by the proportion of macropores. • We have verified the applicability of T 2 -I model (which we have validated in tight sandstone and shale) on igneous rocks. • According to the pore structure, the relationship between transverse relaxation time and resistivity index is established. • We provide a workflow for researchers to use our model to obtain dynamic Archie formula parameters for joint inversion of water saturation using resistivity and NMR logging data. • Finally, we found a very interesting phenomenon. The key parameters in the model are sensitive to diagenesis, and the data show a clear difference between sedimentary rocks and igneous rocks. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) technique is the most innovative tool to determine water saturation. Notwithstanding a solid foundation in theory, current NMR methods have some practical limitations to determine water saturation. The main problem with using the current method is to measure the cut-off value of transverse relaxation time from a large number of water-saturated core samples. Determining the cut-off value in the core laboratory is costly and time-consuming. Hence, this study is aimed at providing a new method for determining water saturation using wavelet transform and the transverse relaxation time log. In this study, the transverse relaxation time log was first decomposed repeatedly by wavelet transform to eliminate the porosity effect, thus achieving immovable fluid relaxation time. Then, water saturation was calculated at each depth using the current NMR method with different cut-off values, referred to as bound water saturation. Finally, by establishing a relation between bound water saturation and immovable fluid relaxation time, water saturation was calculated at each depth, referred to as irreducible water saturation. The results achieved from this study demonstrated that irreducible water saturation closely matches bound water saturation in various oil reservoirs. • Extracting immovable fluid relaxation (T F) time from transverse relaxation time (T 2) • Establishing a relation between T F and water saturation. • Calculating water saturation based on the proposed equation. [ABSTRACT FROM AUTHOR]

There is a growing interest in characterizing the pore structure of reservoir rocks using the low field nuclear magnetic resonance technique. The transverse surface relaxivity is widely appreciated as the most significant parameter to connect the transverse relaxation (T 2) time and the pore size by scientists. In this study, we reviewed long-established and recently developed methods to predict the surface relaxivity over the last few decades. Moreover, the advantages, shortcomings, as well as the applications of the methods were discussed. What's more, the potential causes of affecting the surface relaxivity such as mineralogical compositions, reservoir conditions, fluid properties, and magnetic field strengths were investigated to analyze the controlling factors of the surface relaxivity. Based on the review and analysis, we recommended a composited experiment to measure the surface relaxivity and proposed a possible workflow to obtain the variable surface relaxivity. The review section shows that the surface relaxivity is generally calculated based on the specific surface area. There is no universally accepted method since each of the experiments only probes a part of the pore system or resolves pore size at a different length scale, and it is better to characterize the full-scale pore space using multi-scale experiments. In addition, the constant surface relaxivity may not hold true for heterogeneous reservoir rocks with wide pore size distributions and the presence of paramagnetic minerals. It is a trend to use more than one surface relaxivity according to petrophysical facies or pore types. Multiple regressions may also serve as an effective way to get variable surface relaxivities. Further work needs to be done to develop a comprehensive understanding of the surface relaxivity, especially the influence of the spatial distribution of paramagnetic minerals which are extensively distributed in unconventional reservoirs such as shale and coal. • Conventional methods to quantify the surface relaxivity of reservoir rocks are reviewed. • Influential factors of the surface relaxivity are discussed and analyzed thoroughly. • Recommended methods of transforming relaxation time to pore radius are addressed. [ABSTRACT FROM AUTHOR]

Knowledge of the process and kinetics of solid food disintegration in the human stomach is essential for assessing bioaccessibility of nutrients and understanding gastric emptying. It is desirable to develop advanced techniques for non-invasively and non-destructively studying the kinetics of gastric disintegration and nutrient release during digestion. The main objective of this study was to verify the feasibility of monitoring gastric disintegration of carrot sample during digestion in vitro by a Low-Field Nuclear Magnetic Resonance (LF-NMR) device. Static soaking in different liquid medium was also carried out using as comparison with the LF-NMR data to validate the feasibility. The wet and dry weight retention ratio, water content, hardness and effective diffusivity of the carrot were measured during the soaking tests following a course of time. The transverse relaxation time (T 2) and magnetic resonance imaging (MRI) from the LF-NMR was employed to illustrate the transient water status throughout each sample. The T 23 relaxation time at peak maximum migrated from ~1300 ms to 500 ms after static soaking in the simulated gastric juice with pH of 1.8 for 240 min, with the total peak area decreasing by 9.10% throughout the measurement of T 2 quantitatively supporting the similar reduction of 8.89% in the wet mass retention ratio. Moreover, the time evolutions of the carrot sample size as shown from the MRI imaging results were also in line with the decrease of the solid loss during the static soaking. These consistent results indicate that the LF-NMR provides a non-invasive and non-destructive technique for potentially characterizing the disintegration of solid food samples during gastric digestion. • The gastric disintegration of carrot was investigated in vitro using LF-NMR. • Static soaking tests were carried out as comparison with the LF-NMR data. • Transverse relaxation time (T 2) and MRI results supported the static soaking data. • LF-NMR is a reasonable technique for monitoring gastric digestion of solid food non-invasively. [ABSTRACT FROM AUTHOR]

Based on the analytical 1H low-field nuclear magnetic resonance (NMR) technique, we developed a novel method and corresponding model to analyze the hydration degree (α t) of cement in cement paste under different curing conditions. The hydration degree can be calculated quantitatively based on the transverse relaxation time (T 2) distributions using NMR measurements. The T 2 distributions of the cement paste samples with the water/cement (W/C) ratios of 0.25, 0.35 and 0.45 under standard curing, steam curing at 40 °C and steam curing at 60 °C were obtained. The α t of cement was studied by the hydration heat method and portlandite (CH) quantitative measurements. The results show that the intensity-weighted T 2 value of non-surface water peaks (T 2 ¯) has a significant correlation with α t that can be expressed by an exponential equation. In this paper, the derivation of this exponential equation is given, and the effects of W/C ratio and curing condition on its parameters are analyzed. [ABSTRACT FROM AUTHOR]

This research compared the distribution and mobility of water in the longissimus thoracis muscle of 51 Apulo-Calabrese and 52 crossbred pigs differing in growth performances. The Apulo-Calabrese and crossbreed pigs were fed the same diet and slaughtered at 135 and 155 kg live weight, respectively. Besides meat quality measurement, water status was assessed from transverse relaxation time (T 2) weighted signals registered by Time Domain Nuclear Magnetic Resonance (TD-NMR). A mixed model indicated that Apulo-Calabrese pigs had higher a* (P -value < 0.0001), chroma (P -value < 0.0001) and total intensity (P -value = 0.011) values. A Principal Component Analysis showed that the samples from Apulo-Calabrese had higher scores along Principal Component (PC) 2 (P -value = 4.07 × 10−5) and lower scores along PC3 (P -value = 1.50 × 10−7). However PC2 and PC3 explained a low fraction of the total variance, suggesting that few differences characterize meat quality traits of the two genetic types. • We studied water status and meat quality in Apulo-Calabrese and crossbreed pigs. • Apulo-Calabrese meat had higher percentage of water located outside the myofibrils. • Apulo-Calabrese pigs meat showed higher pH and lower water retention ability. [ABSTRACT FROM AUTHOR]

Background: Doppler ultrasound measurements of the peak systolic velocity of the middle cerebral artery can be used to noninvasively diagnose fetal anemia but are less precise following fetal blood transfusion and in late gestation. We have previously demonstrated the feasibility of estimating fetal hematocrit in vitro using magnetic resonance imaging relaxation times. Here we report the use of magnetic resonance imaging as a noninvasive tool to accurately detect fetal anemia in vivo.Objectives: This study has 2 objectives: (1) to determine the feasibility and accuracy of magnetic resonance imaging in estimating hematocrit in anemic fetuses and (2) to compare magnetic resonance imaging and middle cerebral artery Doppler in detecting moderate to severe fetal anemia.Study Design: Fetuses undergoing fetal blood sampling or transfusion underwent magnetic resonance imaging examinations prior to and following their procedures at 1.5 Tesla (Siemens Avanto). A modified Look-Locker inversion pulse sequence and T2 preparation sequence were applied for T1 and T2 mapping of the intrahepatic umbilical vein. Estimated fetal hematocrit was calculated using a combination of T1 and T2 values and compared with conventional hematocrit obtained from fetal blood samples and middle cerebral artery Doppler measurements.Results: Twenty-three fetuses were assessed during 33 magnetic resonance imaging scans. The mean absolute difference between the laboratory and magnetic resonance imaging-estimated hematocrit was 0.06 ± 0.05 with a correlation of 0.77 (P < .001) determined by a multilevel, mixed-effects model adjusting for the repeated measurements from the same participants, multiple gestation pregnancies, and the scan type (ie, before or after transfusion scan). Bland-Altman analysis revealed a systematic bias of -0.03 between the magnetic resonance imaging and fetal blood sampling measurements. Magnetic resonance imaging and middle cerebral artery Doppler had similar sensitivities of approximately 90% to detect moderate to severe anemia. However, magnetic resonance imaging had a higher specificity (93% [13/14], 95% confidence interval, 66-100%) than Doppler (71% [10/14], 95% confidence interval, 42-92%).Conclusion: Moderate to severe fetal anemia can be detected noninvasively by magnetic resonance imaging with high sensitivity and specificity. Our results suggest an adjunct role for magnetic resonance imaging in fetuses with suspected anemia, particularly following previous transfusion and in late gestation. [ABSTRACT FROM AUTHOR]