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The porosity of differently wetted carbonaceous material with disordered mesoporosity was investigated using low-field 1H NMR relaxometry. Spin–spin relaxation (relaxation time T2) was measured using the CPMG pulse sequence. We present a non-linear optimization method for the conversion of relaxation curves to the distribution of relaxation times by using non-specialized software. Our procedure consists of searching for the number of components, relaxation times, and their amplitudes, related to different types of hydrogen nuclei in the sample wetted with different amounts of water (different water-to-carbon ratio). We found that a maximum of five components with different relaxation times was sufficient to describe the observed relaxation. The individual components were attributed to a tightly bounded surface water layer (T2 up to 2 ms), water in small pores especially supermicropores (2 < T2 < 7 ms), mesopores (7 < T2 < 20 ms), water in large cavities between particles (20–1500 ms), and bulk water surrounding the materials (T2 > 1500 ms). To recalculate the distribution of relaxation times to the pore size distribution, we calculated the surface relaxivity based on the results provided by additional characterization techniques, such as thermoporometry (TPM) and N2/−196 °C physisorption. [ABSTRACT FROM AUTHOR]

Currently, the existence of a gut–bone axis receives massive attention, and while sound premises and indirect proofs exist for the gut–bone axis concept, few studies have provided actual data linking the gut and bone physically. This study aimed to exploit the versatile nature of nuclear magnetic resonance (NMR) to link NMR relaxometry data on bone mineralization with NMR spectroscopic profiling of gut metabolites. For this purpose, sample material was obtained from a 6‐week intervention study with ovariectomized (OVX) rats (n = 49) fed with seven different diets varying in calcium content (0.2–6.0 mg/kg) and prebiotic fiber content (0–5.0% w/w). This design ensured a span in (i) calcium available for bone mineralization and (ii) metabolic activity in the gut. After termination of the intervention, longitudinal (T1), transverse (T2) relaxation, and mechanical bone strength were measured on the excised femur bones. A PLS model with high predictability (Q2 = 0.86, R2 = 0.997) was demonstrated between T2 decay curves and femur mechanical strength. Correlations were established between bone T2 populations and gut short‐chain fatty acids. In conclusion, the present dual NMR approach showed strong correlation between T2 relaxation and mechanical strength of the bone, and when metabolic activity in the gut was modulated by inulin, the potential existence of a gut–bone axis was demonstrated. [ABSTRACT FROM AUTHOR]

The wettability of the inner surfaces in a porous network is challenging to be accessed but essential to understand the complex performance of e.g. particulate systems. Here we investigate the water behavior in the macroporous (50–100 nm) voids of dense particle packings by performing low-field 1H NMR relaxometry in solid silica colloid crystals. The systems chosen guarantee a regular, known void size distribution with controllable water affinity (through thermal annealing), where the NMR experiment clearly discriminates the void water from micropore or bound water contributions, allowing separate monitoring. Analysis of the saturated state indicates that the interparticle voids are completely filled after imbibition, even for less hydrophilic spheres. Due to the interaction with the silica surface, proton relaxation in void water is up to 100 times faster than that in bulk water, serving for assessment of the hydrophilicity within the sample. The relaxation time evolution upon dewetting provides an empirical measurement of the wettability inside the ensemble, revealing a progressively inhomogeneous wetting of increasingly hydrophobic surfaces. Our results provide insight into the imbibition state and dewetting performance in meso - and macroporous systems, with emphasis in the marked influence of the surface nature on the pore wetting distribution. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have great potential as an efficient alternative to current separation and purification procedures of a large variety of solvent mixtures—a critical process in many applications. Due to the huge number of existing MOFs, it is of key importance to identify high-throughput analytical tools, which can be used for their screening and performance ranking. In this context, the present work introduces a simple, fast, and inexpensive approach by compact low-field proton nuclear magnetic resonance (NMR) relaxometry to investigate the efficiency of MOF materials for the separation of a binary solvent mixture. The mass proportions of two solvents within a particular solvent mixture can be quantified before and after separation with the help of a priori established correlation curves relating the effective transverse relaxation times T2eff and the mass proportions of the two solvents. The new method is applied to test the separation efficiency of powdered UiO-66(Zr) for various solvent mixtures, including linear and cyclic alkanes and benzene derivate, under static conditions at room temperature. Its reliability is demonstrated by comparison with results from 1H liquid-state NMR spectroscopy.

Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively.

Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF ¹H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively. [ABSTRACT FROM AUTHOR]

Compact nuclear magnetic resonance (NMR) instruments make NMR spectroscopy and relaxometry accessible in industrial and harsh environments for reaction and process control. An increasing number of applications are reported. To build an interdisciplinary bridge between “process control” and “compact NMR”, we give a short overview on current developments in the field of process engineering such as modern process design, integrated processes, intensified processes along with requirements to process control, model based control, or soft sensing. Finally, robust field integration of NMR systems into processes environments, facing explosion protection or integration into process control systems, are briefly discussed. [ABSTRACT FROM AUTHOR]

Low-field NMR relaxometry is sensitive to molecular mobility within well-defined time windows and can thus be applied to study interactions between polymers and inorganic filler particles in composite materials. Volume fraction and dispersion of the filler influence the polymer chain dynamics, which also modify the macroscopic properties of the polymer composites. As model systems, TiO2-filled poly( n-alkyl methacrylates) with different side-chain lengths and filler contents are prepared by melt mixing. Several 1H NMR relaxation parameters, which are sensitive and selective toward polymer-filler interactions, are investigated at a Larmor frequency of 20 MHz as a function of temperature. Both physical and empirical models are used to analyze the NMR data, and the results are compared with the aim of an unambiguous detection of polymer-filler interactions. [ABSTRACT FROM AUTHOR]

Simple Summary: Breast cancer is the most diagnosed cancer for women, and clear surgical margins in breast-conserving surgery (BCS) are essential for preventing recurrence. In this study, the potential of fast field-cycling 1H-NMR relaxometry as a new tool for intraoperative margin assessment was evaluated. The technique allows the determination of the tissue proton relaxation rates as a function of the applied magnetic field on small tissue samples excised from surgical specimens, at the margins of tumour resection, prior to histopathological analysis. It was found that a good accuracy in margin assessment, i.e., a sensitivity of 92% and a specificity of 85%, can be achieved. The discriminating ability shown by the relaxometric assay relies mainly on the difference of fat/water content between healthy and tumour cells. The information obtained has the potential to support the surgeon in real-time margin assessment during BCS. As conserving surgery is routinely applied for the treatment of early-stage breast cancer, the need for new technology to improve intraoperative margin assessment has become increasingly important. In this study, the potential of fast field-cycling 1H-NMR relaxometry as a new diagnostic tool was evaluated. The technique allows the determination of the tissue proton relaxation rates (R1), as a function of the applied magnetic field, which are affected by the changes in the composition of the mammary gland tissue occurring during the development of neoplasia. The study involved 104 small tissue samples obtained from surgical specimens destined for histopathology. It was found that a good accuracy in margin assessment, i.e., a sensitivity of 92% and a specificity of 85%, can be achieved by using two quantifiers, namely (i) the slope of the line joining the R1 values measured at 0.02 and 1 MHz and (ii) the sum of the R1 values measured at 0.39 and 1 MHz. The method is fast, and it does not rely on the expertise of a pathologist or cytologist. The obtained results suggest that a simplified, low-cost, automated instrument might compete well with the currently available tools in margin assessment. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have great potential as an efficient alternative to current separation and purification procedures of a large variety of solvent mixtures—a critical process in many applications. Due to the huge number of existing MOFs, it is of key importance to identify high-throughput analytical tools, which can be used for their screening and performance ranking. In this context, the present work introduces a simple, fast, and inexpensive approach by compact low-field proton nuclear magnetic resonance (NMR) relaxometry to investigate the efficiency of MOF materials for the separation of a binary solvent mixture. The mass proportions of two solvents within a particular solvent mixture can be quantified before and after separation with the help of a priori established correlation curves relating the effective transverse relaxation times T2eff and the mass proportions of the two solvents. The new method is applied to test the separation efficiency of powdered UiO-66(Zr) for various solvent mixtures, including linear and cyclic alkanes and benzene derivate, under static conditions at room temperature. Its reliability is demonstrated by comparison with results from 1H liquid-state NMR spectroscopy. [ABSTRACT FROM AUTHOR]