Single-sided Nuclear Magnetic Resonance Research Articles

A phenomenological approach on the influence of paramagnetic iron in cement stone on 2D T1-T2 relaxation in single-sided 1H nuclear magnetic resonance

In recent years, there has been an increasing interest in 1H nuclear magnetic resonance (NMR) relaxometry to obtain information on the hydration and porosity of cement stone. By spin-spin (T2), spin-lattice (T1), and combined relaxation studies, new insights were gained on liquid and crystal bound water as well as pore water exchange. A conversion of relaxation times to pore sizes has been developed and shown to give consistent results. In this study, we use single-sided 1H NMR to obtain two-dimensional T1-T2 relaxation distributions on systematically varied cement stone samples as well as hydrated and solid cement phases. Results show a richness in features beyond past studies and are interpreted qualitatively in terms of water found in chemically different pore environments. Both T1 and T2 surface relaxivity of calcium silicate surrounded liquid water linearly correlate with the cement's Fe2O3 content. Results are discussed based on a theory of interacting surface relaxation mechanisms.

Non-Destructive Quantification of Lipid and Water in Fresh Tuna Meat by a Single-Sided Nuclear Magnetic Resonance Scanner

ABSTRACTA portable single-sided nuclear magnetic resonance (NMR) surface scanner was applied to the non-destructive quantification of lipid and water in meat block samples of farmed bluefin tuna (Thunnus thynnus). Proton NMR relaxation measurements of the fresh meat block samples were performed at room temperature in a laboratory. Totally, 34 tuna meat block samples were measured; the required measurement time was approximately 70 s for each sample. The results yielded estimation errors of 3.7 and 2.7 g/100 g for the lipid and water weight fractions, respectively. The investigation depth of the sensor was as deep as 3 cm, which enables the non-destructive quantification of the meat of the intact whole tuna beneath the thick scales, skin, and subcutaneous fat in markets and seafood factories.

Single-sided NMR for the measurement of the degree of cross-linking and curing

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.

Continuum-Scale Modeling of Liquid Redistribution in a Stack of Thin Hydrophilic Fibrous Layers

Macroscale three-dimensional modeling of fluid flow in a thin porous layer under unsaturated conditions is a challenging task. One major issue is that such layers do not satisfy the representative elementary volume length-scale requirement. Recently, a new approach, called reduced continua model (RCM), has been developed to describe multiphase fluid flow in a stack of thin porous layers. In that approach, flow equations are formulated in terms of thickness-averaged variables and properties. In this work, we have performed a set of experiments, where a wet 260hbox {-}upmu hbox {m}-thin porous layer was placed on top of a dry layer of the same material. We measured the change of average saturation with time using a single-sided low-field nuclear magnetic resonance device known as NMR-MOUSE. We have employed both RCM and the traditional Richards equation-based models to simulate our experimental results. We found that the traditional unsaturated flow model cannot simulate experimental results satisfactorily. Very close agreement was obtained by including the dynamic capillary term as postulated by Hassanizadeh and Gray in the traditional equations. The reduced continua model was found to be in good agreement with the experimental result without adding dynamic capillarity term. Moreover, the computational effort needed for RCM simulations was one order of magnitude less than that of traditional models.

Spatially Resolved Measurements of Crosslinking in UV-Curable Coatings Using Single-Sided NMR

The UV-driven photocuring of coatings results in a crosslinked polymeric network. The degree of crosslinking in these coatings is typically assessed via optical spectroscopy; unfortunately, optical methods are typically limited in their maximum depth access. Alternatively, single-sided nuclear magnetic resonance (NMR) can be used to probe the crosslinking of UV-curable coatings in a spatially sensitive manner. Relaxation measurements, which correlate with crosslinking, can be done with a spatial resolution on the order of microns throughout the depth dimension of the coating, regardless of optical transparency of the material. These results can be visualized via a relaxation cross-section that shows the depth at which a particular relaxation value is observed. These measurements are used to probe the effect of a scavenger molecule that is added to the coating mixture, allowing for efficient crosslinking despite the presence of atmospheric oxygen. This method may find purchase in evaluating systems whose crosslinking properties are intentionally varied throughout its thickness; using NMR, these systems, up to approximately one hundred microns thick, can be measured without repositioning or rastering.

Assessing the Performance of Hydrophobing Agents on Concrete Using Nondestructive Single-Sided Nuclear Magnetic Resonance

AbstractSingle-sided nuclear magnetic resonance is a nondestructive analytical technique by which the ingress behavior of hydrophobing agents as well as the properties and performance of the result...

Understanding thermal aging of non-stabilized and stabilized polyamide 12 using 1H solid-state NMR

Noted for its outstanding properties, polyamide 12 (PA12) is widely used in many long-term applications today. Even so, little is known about how exposure to various conditions, including elevated temperatures, induces changes in PA12. Since such information is crucial to ensure its proper function over a long timespan, this current study compares the thermal aging of stabilized and non-stabilized PA12 samples at elevated temperature. For this, a detailed morphological study was for the first time conducted using a combination of 1H solid-state Nuclear Magnetic Resonance (NMR) measurements at high- and low-magnetic field, Fourier-Transform Infrared (FT-IR) spectroscopy, Differential Scanning Calorimetry (DSC), and viscometry measurements. The morphology of both samples characterized in terms of phase composition and chain mobility changes as a function of exposure time, being the most prominent for the non-exposed sample. This study shows also that simple depth-dependent relaxation measurements performed truly non-destructively by single-sided NMR are sensitive enough to monitor the extent of thermo-oxidation in PA12. Supported by DSC, FT-IR, and viscosity data, the NMR results show a complex interplay between annealing and thermo-oxidation. In particular, the NMR results demonstrate that thermo-oxidation affects both the semi-rigid and mobile amorphous phase and they indicate a preferential start of oxidative chain scission in the semi-rigid phase even in the presence of the stabilizers. To our knowledge such effects have never been experimentally observed and reported before.

Nondestructive Evaluation of Thermal Damage in Concrete by Single-Sided Nuclear Magnetic Resonance

AbstractA new technology to coat concrete with coherent layers of glass by flame-spraying is currently developed at the Institutes of Building Materials Research and Mineral Engineering of RWTH Aachen University in Germany through a joint program. A major factor influencing the pull-off strength of the flame-sprayed glass coating is thermally induced damage in the underlying concrete substrate. In this article, the authors present a nondestructive test method using single-sided H1 nuclear magnetic resonance (NMR) to evaluate the thermally induced damage in concrete specimens. The particular NMR device used in this project primarily detects water and can qualitatively assess the water content as well as the relative size of water-filled voids such as pores and cracks. To do so, the specimens are water saturated and subsequently analyzed by NMR. Changes in the NMR-signal are interpreted in terms of change in porosity and development of cracks inside the cement stone as a function of depth from the concrete ...

Spatially Resolved Monitoring of Drying of Hierarchical Porous Organic Networks.

Evaporation kinetics of water confined in hierarchal polymeric porous media is studied by low field nuclear magnetic resonance (NMR). Systems synthesized with various degrees of cross-linker density render networks with similar pore sizes but different response when soaked with water. Polymeric networks with low percentage of cross-linker can undergo swelling, which affects the porosity as well as the drying kinetics. The drying process is monitored macroscopically by single-sided NMR, with spatial resolution of 100 μm, while microscopic information is obtained by measurements of spin-spin relaxation times (T2). Transition from a funicular to a pendular regime, where hydraulic connectivity is lost and the capillary flow cannot compensate for the surface evaporation, can be observed from inspection of the water content in different sample layers. Relaxation measurements indicate that even when the larger pore structures are depleted of water, capillary flow occurs through smaller voids.

Nondestructive Quantification of Local Plasticizer Concentration in PVC by (1)H NMR Relaxometry.

The properties of plasticized poly(vinyl chloride) (PVC) , one of the most important polymers today, are strongly dictated by the concentration of plasticizer. Yet, it has been impossible to quantify this concentration at different positions inside a PVC product without its destruction because of a lack of suitable analytical methods. Thus, this paper introduces a simple, fast, and efficient way to determine truly nondestructively the concentration of plasticizer in PVC by single-sided nuclear magnetic resonance (NMR). With the help of correlation curves between the concentration of plasticizer inside nonaged PVC samples and the corresponding volume-averaged NMR parameters, single-sided NMR allows the quantification of the local concentration of plasticizer in aged PVC plates at different depths by spatially resolved relaxation measurements. The presented approach represents a fundamental step toward in situ characterization of plasticized PVC.

Single-Sided Nuclear Magnetic Resonance as a Non-Invasive Tool to Evaluate Sprayed Polymer Concrete

Single-sided nuclear magnetic resonance (NMR) is a powerful tool to evaluate building-material properties such as layer thickness, moisture content, and ageing. Due to its simple setup, it is potentially applicable on site. It is non-invasive with a high depth resolution and makes a number of parameters for planning and executing the rehabilitation of buildings as well as for quality assurance easy accessible. In this paper, we focus on the quality assurance of a sprayed polymer-concrete (SPC), which was recently developed by Massenberg GmbH and the Institute of Building Materials Research (ibac) for the repair of sewage systems. Single-sided NMR was used to access curing time of the epoxy binder, binder content, layer thickness, and diffusion of acids through the SPC. However, single-sided NMR measurements only give relative values, so calibrations are given where required. While single-sided NMR shows great potential and can be used in various further applications, limitations of resolution, depth and measurement time need to be considered.

Single-sided Nuclear Magnetic Resonance for condition monitoring of cross-linked polyethylene exposed to aggressive media

The potential of single-sided Nuclear Magnetic Resonance (NMR) to monitor truly non-invasive changes in polymer materials during aging under aggressive media is for the first time evaluated. For this, the NMR method is used in combination with other condition monitoring methods including mechanical measurements, mass uptake, and differential scanning calorimetry. It is validated by studying for the first time the aging kinetics of silane cross-linked polyethylene (PEX) exposed to media used in oil and gas production and transportation, including aliphatic and aromatic hydrocarbons, sulphur solvents, and corrosion inhibitors in combination with CO2 and H2S. All investigated parameters changed, with the strongest effects detected for the NMR chain mobility and in the presence of hydrocarbons. Furthermore, a universal linear correlation curve could be established between the depression of the tensile strength and the chain mobility. This result represents a fundamental step towards establishing single-sided NMR as a new analytical tool for in situ condition monitoring of polyethylene working under sour conditions. The proposed approach can be easily extended to other polymer materials.

Development of a Single-Sided Nuclear Magnetic Resonance Scanner for the In Vivo Quantification of Live Cattle Marbling.

Non-invasive in vivo marbling quantification helps owners to choose the optimum nutritional management for growing cattle and buyers to more precisely evaluate grown cattle at auctions. When using time-domain proton nuclear magnetic resonance (NMR) relaxometry, it is possible to quantify muscle and fat separately by taking advantage of the difference in the spin–spin relaxation time (T2) between water molecules in muscles and fat molecules, which would contribute to the non-invasive and objective determination of marbling scores. With this in mind, we developed a prototype NMR scanner (4.1 MHz for protons) using an original single-sided magnetic circuit and a plane radio frequency (RF) coil for use in the non-invasive quantification of water and fat in live cattle. The sensed region of the developed scanner is compact and almost cubical (19 × 19 × 16 mm3) while the investigation depth (the distance from the RF coil to the center of the sensed region) has been lengthened to 30 mm, which is sufficient for the in vivo trapezius muscle measurement of live cattle. Measurements of 17 samples of beef meat blocks kept at 39 °C were taken in a laboratory to successfully obtain the calibration lines used to convert the NMR signals into water and fat weight fractions at correlation coefficients in excess of 0.9. We also showed that each meat sample could be measured in about 10 s with a measurement error as small as approximately 10 wt%. Accordingly, we believe that our prototype scanner would be useful for in vivo marbling measurements of live cattle trapezius muscles.Electronic supplementary materialThe online version of this article (doi:10.1007/s00723-015-0657-4) contains supplementary material, which is available to authorized users.

Influences on the Hydrophobicity of Concrete Surfaces Treated with Alkyl Trialkoxysilanes

Abstract The paper focuses on how alkaline media, UV radiation, and carbonation as well as on-going cement hydration affects hydrophobic treatments of concrete and influences the properties of these water-repellent layers. Single-sided nuclear magnetic resonance measurements show that layers formed by impregnating samples with alkyl trialkoxysilanes are stable even under long-term exposure to alkaline solution and UV radiation, with the damage of the latter being limited to the topmost surface layers. Microstructural changes during accelerated carbonation of blast furnace slag cement based concrete have a major impact on the hydrophobic layer properties, while the carbonation of Portland cement concrete has no influence. On-going hydration additionally influences the hydrophobic layer properties.

Towards Using NMR to Screen for Spoiled Tomatoes Stored in 1,000 L, Aseptically Sealed, Metal-Lined Totes

Nuclear magnetic resonance (NMR) spectroscopy is used to track factory relevant tomato paste spoilage. It was found that spoilage in tomato paste test samples leads to longer spin lattice relaxation times T1 using a conventional low magnetic field NMR system. The increase in T1 value for contaminated samples over a five day room temperature exposure period prompted the work to be extended to the study of industry standard, 1,000 L, non-ferrous, metal-lined totes. NMR signals and T1 values were recovered from a large format container with a single-sided NMR sensor. The results of this work suggest that a handheld NMR device can be used to study tomato paste spoilage in factory process environments.

Calculation of the Sensitive Region of a U-shaped Permanent Magnet for a Single-Sided NMR Spectrometer

With a conventional NMR (Nuclear Magnetic Resonance) spectrometer, the study sample is placed inside the magnet. In contrast, with a single-sided NMR spectrometer, the study sample is outside, but close to the magnet. Single- sided spectrometers can thus be used with a large sample and made portable. A high magnetic field can be achieved without the need for a high-current, DC power supply when using neodymium (NdFeB) magnets. The system is, therefore, relatively low cost, as well. The U-shaped magnet developed here consists of two permanent magnets of size 50x50x25 mm 3 (with a measured surface magnetic field of 0.35 T) placed on a piece of thick steel with opposite poles upward, giving a magnetic field parallel to the surface of the magnets. The magnetic charge model was used to calculate the magnetic field in planes at different distances from the magnets' surface and the size of the NMR sensitive region with 10 3 ppm homogeneity was obtained. Calculated field values and values measured using a tesla meter allowed the values of the surface magnetic charge density σ m to be determined. Magnets positioned with a gap of one-half the width of the magnet face produced the largest sensitive region. In this case, the sensitive region was 12 x 2.5 x 1 mm and located 15 mm above the magnet surface with a central field of 0.23 T.

Optimization and Construction of Single-side Nuclear Magnetic Resonance Magnet

Single-sided NMR devices can operate under conditions inaccessible to conventional NMR while featuring portability and the ability to analyze arbitrary-sized objects. In this paper, a semi-elliptic Halbach magnet array was designed and built for single-side Nuclear Magnetic Resonance (NMR). We present an easy-to-implement target field algorithm for single-side NMR magnet design based on Gram-Schmidt Orthogonal method. The creating magnetic field of designed magnet structure could achieve best flatness in the region of interesting for NMR applications. The optimizing result shows that the best magnet structure can generate magnetic fields which flatly distributed in the horizontal direction and the gradient was distributed in the vertical direction with gradient of 2mT/mm. The field strength and gradient were measured by a three dimensions Hall probe and agreed well with the simulations. DOI: http://dx.doi.org/10.11591/telkomnika.v11i10.3460

Poly(vinyl alcohol)film formation process using single-sided low-field NMR relaxometry: effect of initial concentration

The film formation of Poly(vinyl alcohol) (PVOH) from water solutions of different concentrations has been studied using a low-field, single-sided nuclear magnetic resonance (NMR) scanner. The film formation takes place during the drying of a cast polymer solution under controlled environmental conditions. The NMR scanner allows a vertical (depth) resolution of 50μm up to the formation of the final film of typically 300μm thickness. A depth-dependence of the relaxation time T2 was found as a signature of dynamic heterogeneities in the drying process under which the film is gradually forming. The difference in the dynamics at different heights suggest an increase of local molecular order which is more pronounced towards the air/film interface, for all initial concentrations of the polymer solutions. The relaxation profiles indicate that the onset of dynamical heterogeneity appears at PVOH concentration larger than 25% in all samples.

Measuring the Effectiveness of Hydrophobic Layers Using a Non-Destructive Method

The paper focuses on the relationship between the effective hydrophobic layer thickness and the durability of impregnated hydrophobic treatments using single-sided nuclear magnetic resonance measurements. Weathered and non-weathered specimens were compared to detect the influence of different exposures on the performance of hydrophobic layers. The results show that structural changes caused by carbonation of blast furnace cement based concrete have an effect on the hydrophobic layer thickness while the carbonation of Portland cement concrete has none.

Effects of time and temperature of firing on Fe-rich ceramics studied by Mössbauer spectroscopy and two-dimensional 1H-nuclear magnetic resonance relaxometry

The combined effects of firing temperature and soaking time on the microstructure of iron-rich porous ceramics have been studied by 57Fe-Mössbauer spectroscopy and 2D 1H nuclear magnetic resonance (NMR) relaxometry using a single-sided probe. Examining water-saturated ceramics using the relaxation correlation method, where longitudinal (T1) and transverse (T2) relaxation times are measured concurrently, provides information about firing-induced changes in both porosity (related to T1) and magnetic properties (related to T2). Comparing the information obtained from 1H-NMR analyses with that obtained from Mössbauer spectroscopy (which characterizes changes in iron-bearing species) shows that the T1-T2 NMR correlation technique is very sensitive to even subtle modifications in the magnetic behavior of Fe-bearing species. Moreover, the single-sided NMR approach allows us to perform millimeter-scale depth-resolved measurements, which can be used to non-invasively study the microstructural heterogeneities associated with non-uniform firing effects inside ceramics. This is in contrast to Mössbauer spectroscopy, which requires that the ceramic samples be ground.