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Lubricating greases are an important class of lubricants to reduce wear and friction in moving components. SP [ sp [[1]] SP ] sp Greases consist of a thickener network which includes base oil and additives of typically low molecular weight. As expected, signals from base oil molecules, thickeners and the alkyl chains of additives were clearly detected in the SP 1 sp H-NMR spectra at 80 MHz. This reveals that additives have a strong influence on the interaction of base oil and thickener and might also affect the thickener and its structure. [Extracted from the article]

Abstract: The progress of the cure reaction of hydroxyl-terminated (poly)butadiene (HTPB) and isophorone diisocyanate (IPDI) to a polyurethane is of major importance for the adjustment of process parameters as well as final product properties. Simultaneous low field nuclear magnetic resonance relaxometry and near infrared spectroscopy are applied in-situ to study the progress of the cure reaction with respect to time. The sensitive spots of both methods are coincident, allowing quantitative comparison of the results of both methods, as the same region of the sample is examined. The aim is to get a more comprehensive insight into the reaction by the combination of the two analytical methods. Molecular dynamics as provided by NMR relaxation data and chemical concentration information via near infrared spectroscopy allow detailed monitoring and deeper insight into the complex reaction. [Copyright &y& Elsevier]

Abstract: In the production process of caramel mass it would be desirable to determine the contents of water and fat simultaneously in one single analytical step. In classic time domain NMR methods, the differentiation of water and fat is not sufficiently good as the differences in relaxation times of oils and fats are relatively small. As only signal amplitudes at given times are evaluated in classic time domain NMR, the contrast between the compounds is too small to allow a quantification. Therefore, samples are always pre-dried, allowing the determination of the fat content by time domain NMR. Therefore a new TD-NMR method using a combined relaxation analysis was used, where the magnetisation at a certain time is determined by both T 1 and T 2. This combination leads to an increase of contrast and therefore opens up the possibility of quantification of water and fat by time domain NMR simultaneously. For data-processing, a chemometric method was employed to establish correlation with the results of the reference methods for fat and water content. [Copyright &y& Elsevier]

Magnetic resonance imaging was used to study the impact of Ca 2+ on the fouling behavior of alginate in dead-end and cross-flow filtrations. In situ experiments were performed to measure alginate layer formation and flow behavior during filtration. It was found that magnetic resonance imaging allows for distinguishing different structures of the formed alginate layers. The structure of the alginate layer without the addition of Ca 2+ is a fluid and unordered concentration polarization layer, whereas a dense and stable gel layer is formed on the membrane's surface in case of the filtration of alginate with Ca 2+ . This was in good agreement with data of filtration experiments. To overcome the lack of contrast between alginate and surrounding water, the addition of specific contrast agents was necessary in the case of dead-end filtration. Using tagging methods, the flow profiles during dead-end filtrations were investigated, and it was shown that the addition of Ca 2+ not only influences the fouling layer structure, but also the flow behavior. Furthermore, cross-flow experiments were performed. Here, the outflow effect was successfully used as contrast mechanism. [ABSTRACT FROM AUTHOR]

Cure behavior of unsaturated polyester (UP)/montmorillonite (MMT)/methyl ethyl ketone peroxide (MEKP)/cobalt octoate intercalated nanocomposites with various MMT loadings was investigated by dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). UP/MMT nanocomposites were prepared by sequential mixing. Non-isothermal DSC curves were obtained by applying heating rates ranging from 5 to 20 °C/min. They presented two exothermic peaks, which should correspond to two independent cure reactions. The effective activation energy E a , was determined by applying both the Kissinger’s and Starink’s methods. The results showed slightly higher activation energy for nanocomposites, except for UP/10-MMT. It was found that the dependence of E a on α is complex. All the systems in this study fitted Sesták–Berggren (SB) model in overall reaction controlled kinetics and the corresponding model parameters, n , m , A were obtained, but it was insufficient in depicting the complex reaction kinetics. Transmission electron microscopy data support the formation of a partially delaminated nanocomposite material. UP and nanocomposites showed similar behavior on thermal stability. [ABSTRACT FROM AUTHOR]

For the successful production of functional multiple emulsions, it is crucial to monitor the amount of encapsulated inner phase and thus the encapsulation efficiency EE. In order to do this, only few methods are available for oil-in-water-in-oil emulsions. We compare two possible methods – rheometric determination of EE and determination by NMR. These techniques are applied to OWO emulsions with internally gelled water phase, the main purpose of this being an increased stability against coalescence of inner oil droplets due to reduced droplet movement. It can be seen that both measurement techniques are suitable for qualitative comparison of OWO emulsions’ EE. Harsher processing conditions result in smaller outer droplet sizes and reduced EE. It is also shown that a higher amount of the hydrophilic emulsifier chosen improves the EE at sensitive production. Higher stability is provided by gelling of the water phase by hydrocolloids. [ABSTRACT FROM AUTHOR]

We explore the capability of 1H NMR spectroscopy, relaxation and diffusion for the characterization of thermally-induced degradation of fresh motor oils. Temperature dependent measurements of diffusion show a weak sensitivity to thermal degradation. In contrast, both the transverse relaxation at 1H Larmor frequencies of 20 MHz and 400 MHz, as well as the longitudinal relaxation at 60 kHz showed to be sensitive to thermally-induced effects at measured temperatures within the range −10 °C to 30 °C. Results show that the highest sensitivity significance can be reached by fast field-cycling NMR relaxometry measurements at low magnetic fields. Image 1 • 1H NMR Spectroscopy, Diffusometry and Relaxometry are used to characterize thermally-induced degradation of motor oil. • The sensitivity and capability of detection of each technique is analyzed. • NMR diffusion and longitudinal relaxation are completely insensitive in the MHz regime. • Transverse relaxation is sensitive at low temperatures (around 0 °C or lower). • Longitudinal relaxation measured at 60 kHz and room temperature is much more sensitive. [ABSTRACT FROM AUTHOR]

Biofilm formation during ultrafiltration membrane operation was investigated by Compressed Sensing Magnetic Resonance Imaging (MRI), with tryptic soy broth included in the feed stream to stimulate microbial growth. Biofilm development was visualized as growing layer characterized by reduced T 1 relaxation time, and its progression as monitored by MRI was compared with classical integral filtration parameters such as permeate flux J , transmembrane pressure Δ p and permeability L p to document fouling behavior. Over three days of growth a change in the filtration process could be observed in both measurements, with L p decreasing dramatically over time as the surface-associated biofilm increased in thickness. Following cessation of filtration and the associated drop in Δ p , the biofilm detached from the lumen wall and dispersed throughout the feed channel. Compressed Sensing MRI velocity and intensity measurements facilitate fast imaging during filtration processes, providing new possibilities for the investigation of biofouling in filtration membranes. Image 1 • Biofouling in multichannel hollow fiber membranes is characterized in-situ by MRI. • Biofouling was stimulated with tryptic soy broth in the feed solution. • T 1 -contrast images track biofilm development inside the membrane channels. • Velocity images allow the characterization of flow during filtration. • Compressed Sensing (CS) considerably reduces measurement time. [ABSTRACT FROM AUTHOR]

Sedimentation of opaque suspensions of carbon black and lithium-iron-phosphate was investigated by spin-echo-based magnetic resonance imaging. Optical methods are usually applied to determine settling velocities, but are limited with respect to high concentrations and optical transparency. The presented method uses intensity data from the noninvasively measured magnetic resonance signal of the sample. The settling velocity is obtained from the evolution of the signal intensity profiles based on the contrast in 1H magnetic resonance imaging between particles and liquid. New insights into the sedimentation in opaque suspensions are provided, since the 1H images uncover the spatial distribution of the particles and its agglomerates, as well as the shape of the settling front. Additionally, the sedimentation was experimentally studied using a sedimentation balance, which gravimetrically measures the increase in mass fraction over time due to the settling of particles. By parallel usage of these two methods, the sedimentation processes of opaque suspensions of lithium-ion-battery electrode materials were investigated. The sedimentation balance covers high, technically relevant concentrations. Limiting factors of the methods are discussed, which are mainly signal intensity in the magnetic resonance imaging and the increasing viscosity of highly concentrated suspensions. [ABSTRACT FROM AUTHOR]

Highlights • NMR monitors oil degradation by relaxation and diffusion. • Quality control of oils can be achieved by low field NMR. • Fast field cycling as well as single-sided NMR allow to study oil aging. Abstract Time domain, also named lowfield nuclear magnetic resonance is used to monitor oil degradation by measuring relaxation and diffusion. As quality control of oils is indispensable to optimize oil change intervals while simultaneously preventing machinery damage, the technique was applied to detect the degradation state of engine oils as time domain nuclear magnetic resonance is known as a well suited tool to measure quality control parameters for example in food industry. Correlations with commonly applied oil analytics like viscosity measurements and inductively coupled plasma optical emission spectrometry allow to interpret relaxation and diffusion data in detail and finally to deepen the understanding of oil aging processes. Additionally, the measurement temperature was varied to achieve the maximum sensitivity towards oil aging. Low field NMR is not only realized in form of table top instruments, but also in form of field cycling and single sided NMR devices. Fast field cycling as well as single-sided NMR were also explored to study oil aging and to provide valuable insight. The latter device was used to obtain information about translational diffusion and transverse relaxation of oils simultaneously. [ABSTRACT FROM AUTHOR]

Abstract Polymeric multichannel hollow fiber membranes were developed to reduce fiber breakage and to increase the volume-to-membrane-surface ratio and consequently the efficiency of filtration processes. These membranes are commonly used in ultrafiltration and are operated in in-out dead-end mode. However, some of the filtration details are unknown. The filtration efficiency and flow in the multichannel membranes depend on filtration time and are expected to vary along spatial coordinates. In the current work, in-situ magnetic resonance imaging was used to answer these questions. Velocities were quantified in the feed channels to obtain a detailed understanding of the filtration process. Flow and deposits were measured in each of the seven channels during filtration of sodium alginate, which is a model substance for extracellular polymeric substances occurring in water treatment. Volume flow and flow profiles were calculated from phase contrast flow images. The flow in z -direction in the center channel was higher than in the surrounding channels. Flow profiles variate depending on the concentration of Ca2+, which changes the filtration mechanism of aqueous solutions of sodium alginate from concentration polarization to gel layer filtration. Graphical abstract fx1 Highlights • Filtrations of alginate solutions in multichannel hollow fiber membranes are characterized in-situ by MRI. • Image contrast in structural images is generated by paramagnetic contrast agents. • The filtration characteristics are changing from concentration polarization to gel layer fouling in the presence of Ca2+. • Volume flow and flow profiles in every single channel are analyzed to investigate filtration characteristics. [ABSTRACT FROM AUTHOR]

O/W/O double emulsions are studied by means of 1 H nuclear magnetic resonance (NMR) and confocal laser scanning microscopy (CLSM) with respect to their structural and diffusion properties. Due to the structure of double emulsions, common droplet sizing techniques such as laser scattering methods show limited applicability, especially with respect to the inner droplet size distribution and dynamic effects on the molecular level. However, geometrical and structural information can be extracted from pulsed field gradient stimulated echo (PFG-STE) NMR measurements, as the molecules in the different phases experience hindered and restricted diffusion due to the interfaces. Additionally, the permeability of the interfaces and the diffusion across the intermediate (hetero) phase can be observed either by PFG-STE NMR or by exploiting the possibilities of paramagnetic relaxation enhancement. The NMR results are confirmed by CLSM with respect to both the droplet size distribution and the exchange of molecules in this publication especially for the O/W/O type of double emulsions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Droplet size distribution by NMR diffusometry. [•] Disperse phase ratios by NMR spectroscopy. [•] Molecular exchange between phases via NMR diffusometry and paramagnetic relaxation enhancement. [•] Kinetics of dye diffusion between phases driven by concentration gradients and observed by CLSM. [Copyright &y& Elsevier]

Cross-flow membrane ultrafiltration of the polysaccharide sodium alginate in aqueous solution was investigated in polymeric Helix membranes by in-situ magnetic resonance imaging (MRI) non-invasively and non-destructively. MRI allows velocity and NMR intensity measurements during filtration. In the present case and under the conditions used in the experiments, signal intensity is mainly generated by 1H of water. Lower intensities can therefore be understood as a measure for material accumulation. Compressed sensing allows faster data acquisition, enabling a reliable, time resolved measurement of the ultrafiltration progress. Even under cross-flow filtration conditions, the membrane filtration is impaired by the increasing filtration resistance due to gel layer formation during the filtration of aqueous sodium alginate with CaCl 2. The Helix membrane has an additional helical ridge along the membrane wall to provide fouling inhibition, resulting in a complex three-dimensional flow field that was measured via compressed sensing MRI. Furthermore, the behavior of the deposit was classified more precisely by backwashing in the Helix membrane. Summarizing, the flow field, the deposit formation during cross-flow filtration in a Helix membrane and its backwashing was monitored and investigated by fast MRI methods. [Display omitted] • In-situ cross-flow ultrafiltration in a polymeric Helix membrane with sodium alginate. • Compressed sensing magnetic resonance imaging to measure deposit structure and flow. • Dedicated image processing and modelling of signal intensity data. • Gel layer formation and backwashing of sodium alginate with Ca2+. [ABSTRACT FROM AUTHOR]