An evaluation of kefir grain size with magnetic resonance imaging to observe the fermentation of milkPublished: 22 February 2019 by Wiley in Magnetic Resonance in Chemistry
Kefirian milk is a fermented beverage consumed worldwide. Originally produced in animal skins, it is now prepared both industrially and at home by adding symbiotic cultures of bacteria and yeast known as kefir grains to fresh milk. There is significant literature on the biological aspects of this process but little focus on the fermentation effects on the bulk milk as a function of the grain morphology. Changes in the MR signal as measured using a whole body clinical MRI scanner are found to be proportional to traditional gas measurements with correlation coefficients in excess of 0.95. Magnetic Resonance Imaging is then also used to determine the effect of grain size on the rate of fermentation of milk. It is found that larger grains result in signal intensity changes on the order of 0.03 a.u per hour but by breaking the grains into pieces around 3mm the reaction rate can be more than doubled to 0.07 a.u. per hour. It is thought that this shows promise as a method to improve the speed of production of Kefirian milk and by arresting the process partway through fermentation, gives control over the properties of the end product.
Moisture content of foodstuffs are typically assessed by Titration or Near Infrared Spectroscopy which are labour intensive as a manual measurement or costly when automated. Magnetic Resonance offers a method for moisture evaluation but is also normally costly. In this work we revisit Look and Locker's “Tone Burst” experiment with a marginal oscillator to evaluate moisture content of powdered skimmed milk subjected to increased humidity. We refer to this technique as the Transient Effect Determination of Spin‐Lattice (TEDSpiL) relaxation times. Moisture content in the samples ranged from 0‐12% as determined from the weight gained by the dry powder when re‐suspended in water to reach a concentration of 40% w/v. The relaxation properties of re‐hydrated samples were measured with a CW NMR sensor. Solutions made up from powders with a higher retained moisture content provided lower measured relaxation values providing a method of measuring the moisture content of the powder. This technique provides a moisture measurement in under 5 seconds compared to several minutes for the equivalent pulsed method using low field hardware.
Ex vivo MRI cell tracking of autologous mesenchymal stromal cells in an ovine osteochondral defect modelPublished: 11 January 2019 by Springer Nature in Stem Cell Research & Therapy
Osteochondral injuries represent a significant clinical problem requiring novel cell-based therapies to restore function of the damaged joint with the use of mesenchymal stromal cells (MSCs) leading research efforts. Pre-clinical studies are fundamental in translating such therapies; however, technologies to minimally invasively assess in vivo cell fate are currently limited. We investigate the potential of a MRI- (magnetic resonance imaging) and superparamagnetic iron oxide nanoparticle (SPION)-based technique to monitor cellular bio-distribution in an ovine osteochondral model of acute and chronic injuries. MSCs were isolated, expanded and labelled with Nanomag, a 250-nm SPION, and using a novel cell-penetrating technique, glycosaminoglycan-binding enhanced transduction (GET). MRI visibility thresholds, cellular toxicity and differentiation potential post-labelling were assessed in vitro. A single osteochondral defect was created in the medial femoral condyle in the left knee joint of each sheep with the contralateral joint serving as the control. Cells, either GET-Nanomag labelled or unlabelled, were delivered 1 week or 4.5 weeks later. Sheep were sacrificed 7 days post implantation and immediately MR imaged using a 0.2-T MRI scanner and validated on a 3-T MRI scanner prior to histological evaluation. MRI data demonstrated a significant increase in MRI contrast as a result of GET-Nanomag labelling whilst cell viability, proliferation and differentiation capabilities were not affected. MRI results revealed evidence of implanted cells within the synovial joint of the injured leg of the chronic model only with no signs of cell localisation to the defect site in either model. This was validated histologically determining the location of implanted cells in the synovium. Evidence of engulfment of Nanomag-labelled cells by leukocytes is observed in the injured legs of the chronic model only. Finally, serum c-reactive protein (CRP) levels were measured by ELISA with no obvious increase in CRP levels observed as a result of P21-8R:Nanomag delivery. This study has the potential to be a powerful translational tool with great implications in the clinical translation of stem cell-based therapies. Further, we have demonstrated the ability to obtain information linked to key biological events occurring post implantation, essential in designing therapies and selecting pre-clinical models.
In medicine, temperature changes can indicate important underlying pathologies such as wound infection. While thermographs for the detection of wound infection exist, a textile substrate offers a preferable solution to the designs that exist in the literature, as a textile is very comfortable to wear. This work presents a fully textile, wearable, thermograph created using temperature-sensing yarns. As described in earlier work, temperature-sensing yarns are constructed by encapsulating an off-the-shelf thermistor into a polymer resin micro-pod and then embedding this within the fibres of a yarn. This process creates a temperature-sensing yarn that is conformal, drapeable, mechanically resilient, and washable. This work first explored a refined yarn design and characterised its accuracy to take absolute temperature measurements. The influence of contact errors with the refined yarns was explored seeing a 0.24 ± 0.03 measurement error when the yarn was held just 0.5 mm away from the surface being measured. Subsequently, yarns were used to create a thermograph. This work characterises the operation of the thermograph under a variety of simulated conditions to better understand the functionality of this type of textile temperature sensor. Ambient temperature, insulating material, humidity, moisture, bending, compression and stretch were all explored. This work is an expansion of an article published in The 4th International Conference on Sensor and Applications.
Embedding temperature sensors within textiles provides an easy method for measuring skin temperature. Skin temperature measurements are an important parameter for a variety of health monitoring applications, where changes in temperature can indicate changes in health. This work uses a temperature sensing yarn, which was fully characterized in previous work, to create a series of temperature sensing garments: armbands, a glove, and a sock. The purpose of this work was to develop the design rules for creating temperature sensing garments and to understand the limitations of these devices. Detailed design considerations for all three devices are provided. Experiments were conducted to examine the effects of contact pressure on skin contact temperature measurements using textile-based temperature sensors. The temperature sensing sock was used for a short user trial where the foot skin temperature of five healthy volunteers was monitored under different conditions to identify the limitations of recording textile-based foot skin temperature measurements. The fit of the sock significantly affected the measurements. In some cases, wearing a shoe or walking also heavily influenced the temperature measurements. These variations show that textile-based foot skin temperature measurements may be problematic for applications where small temperature differences need to be measured.
Therapeutic Benefit for Late, but Not Early, Passage Mesenchymal Stem Cells on Pain Behaviour in an Animal Model of Oste...Published: 24 December 2017 by Hindawi Limited in Stem Cells International
Mesenchymal stem cells (MSCs) have a therapeutic potential for the treatment of osteoarthritic (OA) joint pathology and pain. The aims of this study were to determine the influence of a passage number on the effects of MSCs on pain behaviour and cartilage and bone features in a rodent model of OA. Rats underwent either medial meniscal transection (MNX) or sham surgery under anaesthesia. Rats received intra-articular injection of either 1.5 × 106 late passage MSCs labelled with 10 μg/ml SiMAG, 1.5 × 106 late passage mesenchymal stem cells, the steroid Kenalog (200 μg/20 μL), 1.5 × 106 early passage MSCs, or serum-free media (SFM). Sham-operated rats received intra-articular injection of SFM. Pain behaviour was quantified until day 42 postmodel induction. Magnetic resonance imaging (MRI) was used to localise the labelled cells within the knee joint. Late passage MSCs and Kenalog attenuated established pain behaviour in MNX rats, but did not alter MNX-induced joint pathology at the end of the study period. Early passage MSCs exacerbated MNX-induced pain behaviour for up to one week postinjection and did not alter joint pathology. Our data demonstrate for the first time the role of a passage number in influencing the therapeutic effects of MSCs in a model of OA pain.
Novel food-safe spin-lattice relaxation time calibration samples for use in magnetic resonance sensor developmentPublished: 14 November 2017 by MDPI AG in Proceedings
<p>Sensors based on the measurement of nuclear magnetic resonance (NMR) relaxation times have been increasing in popularity, due in part to developments in permanent magnet technology. Such sensors tend to measure the spin-lattice (longitudinal) relaxation time T<sub>1</sub>, or the effective spin-spin (transverse) relaxation time T<sub>2</sub><sup>eff</sup>. It is important when developing sensors that there are a range of safe and repeatable calibration samples to aid in their calibration and testing. For the spin-spin relaxation times different viscosities of PDMS oil provide a suitable range of safe test materials. However, for the spin-lattice relaxation times, available options are not as safe to use and typically consist of different concentrations of Nickel Sulphate or Copper Sulfate solutions. In this work we report the use of solutions and gels comprising full fat milk powder as a safe and inexpensive material that can affect the longitudinal relaxation Time over a very wide range of values. We demonstrate that concentrations in distilled water from 5% to 64% give T<sub>1 </sub>values from 1.8s down to 348 ms respectively. In addition to demonstrating their effectiveness for magnetic resonance sensors, validation of the range of T<sub>1</sub> values is undertaken on a high field clinical MRI system.</p>
<p>Body temperature is an important parameter to measure in a number of fields such as medicine and sport. In medicine temperature changes can indicate underlying pathologies such as wound infections, while in sport temperature can be associated to a change in performance. In both cases a wearable temperature monitoring solution is preferable. In earlier work a temperature sensing yarn has been developed and characterised. The yarns were constructed by embedding an off-the-shelf thermistor into a polymer resin micro-pod and then into the fibres of a yarn. This process created a temperature sensing yarn that was conformal, drapeable, mechanically resilient, and washable. This work builds on this early study with the purposes of identifying the steady state error bought about on the temperature measurements as a result of the polymer resin and yarn fibres. Here a wider range of temperatures than previously explored were investigated. Additionally two types of polymer resin with different thermal properties have been tested, with varying thicknesses, for the encapsulation of the thermistor. This provides useful additional information for optimising the temperature sensing yarn design.</p>
Advances in Electronics Prompt a Fresh Look at Continuous Wave (CW) Nuclear Magnetic Resonance (NMR)Published: 23 October 2017 by MDPI in Electronics
Continuous Wave Nuclear Magnetic Resonance (CW-NMR) was a popular method for sample interrogation at the birth of magnetic resonance but has since been overlooked by most in favor of the now more popular pulsed techniques. CW-NMR requires relatively simple electronics although, for most designs, the execution is critical to the successful implementation and sensitivity of the system. For decades there have been reports in the literature from academic groups showing the potential of magnetic resonance relaxation time measurements in industrial applications such as the production of food and drink. However, the cost, complexity and power consumption of pulsed techniques have largely consigned these to the literature. Advances in electronics and developments in permanent magnet technology now require a fresh look at CW-NMR to see if it is capable of providing cost effective industrial solutions. In this article, we review the electronics that are needed to undertake a continuous wave NMR experiment starting with early designs and journeying through the literature to understand the basic designs and limitations. We then review the more recent developments in this area and present an outlook for future work in the hope that more of the scientific community will take a fresh look at CW-NMR as a viable and powerful low-cost measurement technique.
Textiles provide an ideal structure for embedding sensors for medical devices. Skin temperature measurement is one area in which a sensor textile could be particularly beneficial; pathological skin is normally very sensitive, making the comfort of anything placed on that skin paramount. Skin temperature is an important parameter to measure for a number of medical applications, including for the early detection of diabetic foot ulcer formation. To this end an electronic temperature-sensor yarn was developed by embedding a commercially available thermistor chip into the fibres of a yarn, which can be used to produce a textile or a garment. As part of this process a resin was used to encapsulate the thermistor. This protects the thermistor from mechanical and chemical stresses, and also allows the sensing yarn to be washed. Building off preliminary work, the behaviour and performance of an encapsulated thermistor has been characterised to determine the effect of encapsulation on the step response time and absolute temperature measurements. Over the temperature range of interest only a minimal effect was observed, with step response times varying between 0.01–0.35 s. A general solution is presented for the heat transfer coefficient compared to size of the micro-pod formed by the encapsulation of the thermistor. Finally, a prototype temperature-sensing sock was produced using a network of sensing yarns as a demonstrator of a system that could warn of impending ulcer formation in diabetic patients.
A magnetic resonance disruption (MaRDi) technique for the detection of surface immobilised magnetic nanoparticlesPublished: 01 January 2017 by Royal Society of Chemistry (RSC) in Analytical Methods
The relative quantity of surface bound magnetic nanoparticles can be determined by measuring how much the signal measured from a suitable liquid covering the surface is disrupted. There are numerous assays that result in a surface with bound magnetic nanoparticles (MNP) whose number is proportional to the concentration of the analyte of interest. The techniques used to explore such assays are typically complex and costly. Since the presence of such MNP disrupts the pulsed magnetic resonance signal that would normally be detected from a fluid covering the surface, we present a measurement technique to quantify such assays. In this work we identify and characterise a suitable fluid for such measurements, namely 10 cSt viscosity PDMS oil of thickness 250 μm. We demonstrate that the T eff2 relaxation time from the PDMS reduces as the proportion of the surface area covered with MNP increases. Most significant however, is a linear decrease in the signal amplitude from the PDMS as a function of MNP coverage. This is observed both for the integral over 4096 echoes and also in the first echo promising simplified console electronics for rapid measurements.
Clogging Measurement, Dissolved Oxygen and Temperature Control in a Wetland Through the Development of an Autonomous Ree...Published: 27 August 2016 by Springer Nature in Natural and Constructed Wetlands
This is an overview of the hydride-containing catalysts prepared in the Morris group for the efficient hydrogenation of simple ketones, imines, nitriles and esters and the asymmetric hydrogenation and transfer hydrogenation of prochiral ketones and imines. The work was inspired by and makes use of Noyori metal-ligand bifunctional concepts involving the hydride-ruthenium amine-hydrogen HRuNH design. It describes the synthesis and some catalytic properties of hydridochloro, dihydride and amide complexes of ruthenium and in one case, osmium, with monodentate, bidentate and tetradentate phosphorus and nitrogen donor ligands. The iron hydride that has been identified in a very effective asymmetric transfer hydrogenation process is also mentioned. The link between the HMNH structure and the sense of enantioinduction is demonstrated by use of simple transition state models.
Forced aeration of horizontal subsurface flow constructed wetlands (HSSF CWs) is nowadays a recognized method to improve treatment efficiency, mainly in terms of ammonium removal. While numerous investigations have been reported testing constant aeration, scarce information can be found about the efficiency of intermittent aeration. This study aims at comparing continuous and intermittent aeration, establishing if there is an optimal regime that will increase treatment efficiency of HSSF CWs whilst minimizing the energy requirement. Full and intermittent aeration were tested in a pilot plant of three HSSF CWs (2.64m(2) each) fed with primary treated wastewater. One unit was fully aerated; one intermittently aerated (i.e. by setting a limit of 0.5mg/L dissolved oxygen within the bed) with the remaining unit not aerated as a control. Results indicated that intermittent aeration was the most successful operating method. Indeed, the coexistence of aerobic and anoxic conditions promoted by the intermittent aeration resulted in the highest COD (66%), ammonium (99%) and total nitrogen (79%) removals. On the other hand, continuous aeration promotes ammonium removal (99%), but resulted in nitrate concentrations in the effluent of up to 27mg/L. This study demonstrates the high potential of the intermittent aeration to increase wastewater treatment efficiency of CWs providing an extreme benefit in terms of the energy consumption.
Autonomous magnetic labelling of functional mesenchymal stem cells for improved traceability and spatial control in cell...Published: 06 May 2016 by Wiley in Journal of Tissue Engineering and Regenerative Medicine
Mesenchymal stem cells (MSCs) represent a valuable resource for regenerative medicine treatments for orthopaedic repair and beyond. Following developments in isolation, expansion and differentiation protocols, efforts to promote clinical translation of emerging cellular strategies now seek to improve cell delivery and targeting. This study shows efficient live MSC labelling using silica‐coated magnetic particles (MPs), which enables 3D tracking and guidance of stem cells. A procedure developed for the efficient and unassisted particle uptake was shown to support MSC viability and integrity, while surface marker expression and MSC differentiation capability were also maintained. In vitro, MSCs showed a progressive decrease in labelling over increasing culture time, which appeared to be linked to the dilution effect of cell division, rather than to particle release, and did not lead to detectable secondary particle uptake. Labelled MSC populations demonstrated magnetic responsiveness in vitro through directed migration in culture and, when seeded onto a scaffold, supporting MP‐based approaches to cell targeting. The potential of these silica‐coated MPs for MRI cell tracking of MSC populations was validated in 2D and in a cartilage repair model following cell delivery. These results highlight silica‐coated magnetic particles as a simple, safe and effective resource to enhance MSC targeting for therapeutic applications and improve patient outcomes. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.
Temperature dependence of magnetic resonance probes for use as embedded sensors in constructed wetlandsPublished: 01 April 2016 by Elsevier BV in Sensors and Actuators A: Physical
Highlights•Magnetic resonance sensors work over an environmentally relevant range of temperatures.•Signal losses at the temperature range extremities are characterised and explained.•Data is recorded in an operational wetland over 203 days. AbstractConstructed wetlands are now accepted as an environmentally friendly means of wastewater treatment however, their effectiveness can be limited by excessive clogging of the pores within the gravel matrix, making this an important parameter to monitor. It has previously been shown that the clog state can be characterised using magnetic resonance (MR) relaxation parameters with permanent magnet based sensors. One challenge with taking MR measurements over a time scale on the order of years is that seasonal temperature fluctuations will alter both the way that the sensor operates as well as the relaxation times recorded. Without an understanding of how the sensor will behave under different temperature conditions, meaningful information about the clog state cannot be successfully extracted from a wetland. This work reports the effect of temperature on a permanent magnet based MR sensor to determine if the received signal intensity is significantly compromised as a result of large temperature changes, and whether meaningful relaxation data can be extracted over the temperature range of interest. To do this, the central magnetic field of the sensor was monitored as a function of temperature, showing an expected linear relationship. Signal intensity was measured over a range of temperatures (5 °C to 44 °C) for which deterioration at high and low temperatures compared to room temperature was observed. The sensor was still operable at the extremes of this range and the reason for the signal loss has been studied and explained. Spin-lattice relaxation time measurements using the sensor at different temperatures have also been taken on a water sample and seem to agree with literature values. Further to this, measurements have been taken in an operational wetland over the course of 203 days and have shown a linear dependence with temperature as would be expected. This work concluded that the sensor can perform the task of measuring the spin-lattice relaxation time over the required temperature range making it suitable for long-term application in constructed wetlands.
The spontaneous penetration of a wetting liquid into a vertical tube against the force of gravity and the imbibition of the same liquid into a horizontal tube (or channel) are both driven by capillary forces and described by the same fundamental equations. However, there have been few experimental studies of the transition from one orientation to the other. We report systematic measurements of capillary penetration of polydimethylsiloxane oils of viscosities 9.6, 19.2, and 48.0 mPa·s into glass capillary tubes. We first report the effect of tube radii R between 140 and 675 μm on the dynamics of spontaneous imbibition. We show that the data can be fitted using the exact numerical solution to the governing equations and that these are similar to fits using the analytical viscogravitational approximation. However, larger diameter tubes show a rate of penetration slower than expected using an equilibrium contact angle and the known value of liquid viscosity. To account for the slowness, an increase in viscosity by a factor (η/ρ)(scaling) is needed. We show full agreement with theory requires the ratio R/κ(-1) ∼ 0.1 or less, where κ(-1) is the capillary length. In addition, we propose an experimental method that enables the determination of the dynamic contact angle during imbibition, which gives values that agree with the literature values. We then report measurements of dynamic penetration into the tubes of R = 190 and 650 μm for a range of inclination angles to the horizontal, φ, from 5 to 90°. We show that capillary penetration can still be fitted using the viscogravitational solution, rather than the Bosanquet solution which describes imbibition without gravity, even for inclination angles as low as 10°. Moreover, at these low angles, the effect of the tube radius is found to diminish and this appears to relate to an effective capillary length, κ(-1)(φ) = (γ(LV)/ρg sin φ)(1/2).
Non-invasive measurements of the dry solids content of whole potatoes using unilateral magnetic resonance: towards autom...Published: 01 January 2016 by IM Publications Open LLP in Proceedings of the XIII International Conference on the Applications of Magnetic Resonance in Food Science
<p>Sensors that measure magnetic resonance relaxation times are increasingly finding applications in areas such as food and drink authenticity and waste water treatment process control. Modern permanent magnets are used to provide the static magnetic field in many commercial instruments and advances in electronics, such as field programmable gate arrays, have provided lower cost console electronics for generating the series of RF pulses and detecting the resultant magnetic resonance signals. One area that still remains prohibitively expensive for many sensor applications of pulsed magnetic resonance is the requirement for a high frequency power amplifier. With many permanent magnet sensors providing a magnetic field in the 0.25T to 0.5T range, a power amplifier that operates in the 10MHz to 20MHz rage is required. This frequency range falls at the low end of the amateur “ham” radio frequency spectra designated for private recreation and non-commercial exchange of messages. In this work we demonstrate that low cost commercial amateur radio amplifiers can be simply modified, to operate as pulsed magnetic resonance power amplifiers. We demonstrate two amplifier systems, one medium power that can be constructed for less than Euro 100 and a second higher power system which produces comparable results to commercial pulse amplifiers that are an order of magnitude more expensive. Data is presented using both the commercial NMR MOUSE and a permanent magnet system used for monitoring the clog state of constructed wetlands. </p>
<p>Magnetic resonance relaxometry, conducted by field cycling, has become an increasingly popular technique in recent years. In particular, it has the ability to monitor biomass transformation which is of particular interest to wastewater treatment. Traditional field cycling often uses expensive and large electromagnets. In this work we present a small, portable field cycling sensor which can detect changes in biomass in constructed wetland samples. </p> <p>Fast field cycling is a technique that uses a varying magnetic field applied to a sample, polarising it at a high field, allowing it time to develop at a lower field and then collecting the data at the same initial high field. This change in T<sub>1</sub> can reveal interesting properties of the samples not achievable by traditional methods. </p> <p>A desktop magnetic resonance sensor that undertakes relaxometry measurements using field cycling has been developed using a combination of permanent magnets and electrical coils which has been used to test a range of samples. We demonstrate the effectiveness of this sensor by conducting measurements of T<sub>1</sub> at different field strengths for wetland samples at different stages of biofilm growth.</p>
<p>Low-cost magnetic resonance (MR) sensors have in recent years been used to investigate a number of systems by measuring the relaxation times T<sub>1</sub> and T<sub>2</sub><sup>eff</sup>. These values vary in line with changes in many systems giving the investigator a useful non-invasive probe. While the use of MR for in-line or on-line process monitoring in the food industry is not a novel concept, much of the work conducted previously has involved acquiring spatially resolved data which requires a magnetic resonance imaging system. These are both expensive to purchase and maintain, occupy large amounts of space and present problems with safety. In this work we show the value that a very inexpensive (<£100) MR sensor can bring to process monitoring. An MR sensor utilising an eight-element Halbach cylinder with internal diameter of 10mm has been constructed giving a highly uniform magnetic field yielding a strong signal-to-noise ratio. It is shown to be useful for assessing the relaxation times of a range of relevant samples.</p>
Assessing the economic suitability of aeration and the influence of bed heating on constructed wetlands treatment effici...Published: 01 October 2015 by Elsevier BV in Ecological Engineering
ChemInform Abstract: An Unsymmetrical Iron Catalyst for the Asymmetric Transfer Hydrogenation of Ketones.Published: 01 October 2015 by Wiley in ChemInform
The new iron(II)(Ph2P-NH-N-PCy2) complex possessing a dicyclohexylphosphino group trans to the NH group efficiently catalyzes the asymmetric transfer hydrogenation of prochiral ketones furnishing the corresponding alcohols with high enantioselectivity.
The industrial chemistry of the modern world is following a general trend of becoming more sustainab…
In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500.
Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application. With beginnings in borehole logging for the petro-chemical industry Magnetic Resonance sensors have been applied to fields as varied as online process monitoring for food manufacture and medical point of care diagnostics. This great diversity is seeing exciting developments in magnetic resonance sensing technology published in application specific journals where they are often not seen by the wider sensor community. It is clear that there is enormous interest in magnetic resonance sensors which represents a significant growth area. The aim of this special edition of Sensors was to address the wide distribution of relevant articles by providing a forum to disseminate cutting edge research in this field in a single open source publication.
ChemInform Abstract: Iron(II) Complexes Containing Unsymmetrical P-N-P′ Pincer Ligands for the Catalytic Asymmetric Hydr...Published: 07 August 2014 by Wiley in ChemInform
The designed title complexes are successfully applied in the reduction of several aliphatic and aromatic substituted ketones and imines with moderate to high enantioselectivities.
Constructed wetlands are an environmentally considerate means of water purification. Automating parameters such as heating and aeration may extend the lifetime of constructed wetlands and allow for superior waste-water treatment. One critical parameter to monitor in a wetland system is clogging of pores within the gravel matrix, as this limits the viable lifetime of the system. It has previously been observed in a laboratory setting that magnetic resonance (MR) relaxation measurements, T<sub>1</sub> and T<sub>2</sub><sup>eff</sup>, can be used to characterise the clogging state. Various open-geometry MR sensors have been constructed using permanent neodymium magnets with the view of long-term embedding as part of the EU FP7 project ARBI (Automated Reed Bed Installations). The ultimate aim is to monitor clogging levels over the lifetime of the reed bed using MR techniques. One issue with taking various MR measurements over such an extreme time scale, in this case years, is that temperature fluctuations will significantly alter the magnetic field strength produced by the sensors constituent magnets. While the RF transmit-receive circuit has been built so that MR can still be conducted at a range of frequencies without altering the tuning or matching of the circuit, this will result in poor RF excitation if the magnetic field strength shifts significantly. This work investigates the effect that temperature has on the a MR sensor intended for embedding, to determine whether received signal intensity is compromised significantly at large temperature changes.
Snails enjoying eating the leaves of many garden plants and deterring this pest without resorting to chemicals can present a significant challenge. A previous report (PLoS ONE 7(5): e36983) suggested that loose soot was a surface to which snails found adhesion difficult. Soot may also be embedded into PDMS substrate making a flexible membrane with superhydrophobic properties (Appl. Phys. Lett. 102 (21) 214104). In this article we investigate if the embedded soot has the same anti-adhesive properties to snails as the loose soot, so giving the possibility of a facile method for protecting crops from this pest. Data is presented showing the force required to remove snails from the soot/PDMS surfaces using a simple spinning technique. The advancing an receding contact angles have also been measured for various concentrations of an anionic surfactant on the soot/PDMS surface and compared to the data presented in the PLoS ONE article. In addition, simple time lapse video demonstrations are presented that show the reluctance of the snails to move over the soot based surfaces suggesting that the soot/PDMS structure does indeed provide a level of deterrence to this garden pest.
ChemInform Abstract: Amine(imine)diphosphine Iron Catalysts for Asymmetric Transfer Hydrogenation of Ketones and Imines.Published: 23 April 2014 by Wiley in ChemInform
The synthesis of novel enantiopure amine(imine)diphosphine catalysts that take advantage of the iron(II) ion as a template is described.
The detection of adulteration in edible oils is a concern in the food industry, especially for the higher priced virgin olive oils. This article presents a low field unilateral nuclear magnetic resonance (NMR) method for the detection of the adulteration of virgin olive oil that can be performed through sealed bottles providing a non-destructive screening technique. Adulterations of an extra virgin olive oil with different percentages of sunflower oil and red palm oil were measured with a commercial unilateral instrument, the profile NMR-Mouse. The NMR signal was processed using a 2-dimensional Inverse Laplace transformation to analyze the transverse relaxation and self-diffusion behaviors of different oils. The obtained results demonstrated the feasibility of detecting adulterations of olive oil with percentages of at least 10% of sunflower and red palm oils.
A variety of insect and arachnid species are able to remain submerged in water indefinitely using plastron respiration. A plastron is a surface-retained film of air produced by surface morphology that acts as an oxygen-carbon dioxide exchange surface. Many highly water repellent and hydrophobic surfaces when placed in water exhibit a silvery sheen which is characteristic of a plastron. In this article, the hydrophobicity of a range of commercially available water repellent fabrics and polymer membranes is investigated, and how the surface of the materials mimics this mechanism of underwater respiration is demonstrated allowing direct extraction of oxygen from oxygenated water. The coverage of the surface with the plastron air layer was measured using confocal microscopy. A zinc/oxygen cell is used to consume oxygen within containers constructed from the different membranes, and the oxygen consumed by the cell is compared to the change in oxygen concentration as measured by an oxygen probe. By comparing the membranes to an air-tight reference sample, it was found that the membranes facilitated oxygen transfer from the water into the container, with the most successful membrane showing a 1.90:1 ratio between the cell oxygen consumption and the change in concentration within the container.
Whole body tracking of superparamagnetic iron oxide nanoparticle-labelled cells – a rheumatoid arthritis mouse modelPublished: 17 October 2013 by Springer Nature in Stem Cell Research & Therapy
The application of mesenchymal stem cells (MSCs) in treating rheumatoid arthritis (RA) has been made possible by the immunosuppressive and differentiation abilities of these cells. A non-invasive means of assessing cell integration and bio-distribution is fundamental in evaluating the risks and success of this therapy, thereby enabling clinical translation. This paper defines the use of superparamagnetic iron oxide nanoparticles (SPIONs) in conjunction with magnetic resonance imaging (MRI) to image and track MSCs in vivo within a murine model of RA. Murine MSCs (mMSCs) were isolated, expanded and labelled with SiMAG, a commercially available particle. In vitro MRI visibility thresholds were investigated by labelling mMSCs with SiMAG with concentrations ranging from 0 to 10 μg/ml and resuspending varying cell doses (103 to 5 × 105 cells) in 2 mg/ml collagen prior to MR-imaging. Similarly, in vivo detection thresholds were identified by implanting 3 × 105 mMSCs labelled with 0 to 10 μg/ml SiMAG within the synovial cavity of a mouse and MR-imaging. Upon RA induction, 300,000 mMSCs labelled with SiMAG (10 μg/ml) were implanted via intra-articular injection and joint swelling monitored as an indication of RA development over seven days. Furthermore, the effect of SiMAG on cell viability, proliferation and differentiation was investigated. A minimum particle concentration of 1 μg/ml (300,000 cells) and cell dose of 100,000 cells (5 and 10 μg/ml) were identified as the in vitro MRI detection threshold. Cell viability, proliferation and differentiation capabilities were not affected, with labelled populations undergoing successful differentiation down osteogenic and adipogenic lineages. A significant decrease (P < 0.01) in joint swelling was measured in groups containing SiMAG-labelled and unlabelled mMSCs implying that the presence of SPIONs does not affect the immunomodulating properties of the cells. In vivo MRI scans demonstrated good contrast and the identification of SiMAG-labelled populations within the synovial joint up to 7 days post implantation. This was further confirmed using histological analysis. We have been able to monitor and track the migration of stem cell populations within the rheumatic joint in a non-invasive manner. This manuscript goes further to highlight the key characteristics (biocompatible and the ability to create significant contrast at realistic doses within a clinical relevant system) demonstrated by SiMAG that should be incorporated into the design of a new clinically approved tracking agent.
The traditional British pork pie consists of roughly chopped pork cooked in a hot water pastry crust. Due to shrinkage of the meat during cooking, the gap formed around the meat is usually sealed using a gelatin based jelly to exclude air and thus help to preserve the pie. The properties of the jelly are such that it will ingress into the pastry crust causing undesirable softening. The jelly is traditionally produced by simmering pig trotters with seasoning for several hours. In this work we demonstrate the potential of magnetic resonance imaging (MRI) as a tool for investigating the conditions required for producing jellies with different properties and present two examples of this use. Firstly we demonstrate that MRI can determine the ability of water to diffuse through the jelly which is critical in minimizing the amount of moisture moving from the jelly to the crust. Secondly, the impact of jelly temperature on the penetration length into the crust is investigated. These examples highlight the power of MRI as a tool for food assessment.
Monitoring accelerated clogging of a model horizontal sub-surface flow constructed wetland using magnetic resonance tran...Published: 29 May 2013 by Springer Nature in International Journal of Environmental Science and Technology
Horizontal sub-surface flow wetlands are essentially a bed of porous material in which suitable plants are grown to facilitate the removal of organic matter and particulates from wastewater. The aim of this study is to assess the reliability and accuracy of magnetic resonance transverse relaxation time for monitoring clogging development in a constructed wetland. In this study, three different horizontal sub-surface flow constructed wetland models have been produced using tubes packed with different sizes of glass beads with diameter 3, 8 and 14 mm. Accelerated clogging has been achieved by pumping sludge extracted from a real clogged wetland through the bead pack. A desktop MRI tomography system has been used to monitor the transverse relaxation rate as a function of position along the tube and hydraulic conductivity. To corroborate the clogging with magnetic resonance measurements, the head loss was monitored to determine the hydraulic conductivity. Using a bi-exponential fit to the spin echo train data, the slow relaxation rate contribution shows good correlation with the changing hydraulic conductivity. Both fast and slow contributions map well to the expected clog patterns for a constructed wetland. We have demonstrated that there is a linear correlation between the hydraulic conductivity and both parameters of a bi-exponential fit to R2eff, but particularly for the case of the short T2 component.
Magnetic resonance imaging is a widely used technique for medical and materials imaging. Even though the objects being imaged are often irregularly shaped, suitable coils permitting the measurement of the radio-frequency signal in these systems are usually made of solid copper. One problem often encountered is how to ensure the coils are both in close proximity and conformal to the object being imaged. Whilst embroidered conductive threads have previously been used as antennae in mobile telecommunications applications, they have not previously been reported for use within magnetic resonance. In this paper we show that an embroidered single loop coil can be used in a commercial unilateral nuclear magnetic resonance system as an alternative to a solid copper. Data is presented showing the determination of both longitudinal (T1) and effective transverse (T2eff) relaxation times for a flat fabric coil and the same coil conformed to an 8 cm diameter cylinder. We thereby demonstrate the principles required for the wider use of fabric based conformal coils within nuclear magnetic resonance and magnetic resonance imaging.
ChemInform Abstract: Asymmetric Transfer Hydrogenation of Ketimines Using Well-Defined Iron(II)-Based Precatalysts Conta...Published: 18 December 2012 by Wiley in ChemInform
N‐Phosphinoylketimines are reduced by iPrOH to the corresponding amines with 95—99% enantioselectivity at low catalyst loading of iron(II)‐complex FER.
Quantitation of MRI sensitivity to Quasi-monodisperse microbubble contrast agents for spatially resolved manometryPublished: 11 December 2012 by Wiley in Magnetic Resonance in Medicine
The direct in‐vivo measurement of fluid pressure cannot be achieved with MRI unless it is done with the contribution of a contrast agent. No such contrast agents are currently available commercially, whilst those demonstrated previously only produced qualitative results due to their broad size distribution. Our aim is to quantitate then model the MR sensitivity to the presence of quasi‐monodisperse microbubble populations.
Stenocara Gracilipes (the Namib Desert beetle) is a desert dwelling beetle which has adapted to make use of fog as an alternative water source in an environment which receives little rain water. Using a combination of hydrophobic and hydrophilic areas on its carapace, the beetle is able to collect condensation on its back which is then channelled towards the mouth. In this paper we attempt to mimic this effect by selectively altering the hydrophobicity of a number of water repellent fabrics. Fabrics were treated using Granger’s Extreme Wash-in to make them hydrophobic and then laser etched to alter the hydrophobicity. We show a clear relationship between the hydrophobicity of the fabric and the laser energy applied to the surface. Laser etching was used to create a herring bone pattern of channels on the surface of the fabrics. Water sprayed onto the surface preferentially followed the channels into a collection vessel, giving a collection efficiency of 81%. To replicate real world conditions dry ice was used to create fog which was then blown, using an electric fan, onto the fabric at a speed of approximately 2.5 km/h. The water vapour condensed on the surface and then followed the channels into a collection vessel. It was found that the patterned fabrics achieved a collection rate of 0.31 l h−1 m−2.
ChemInform Abstract: The Hydrogenation of Molecules with Polar Bonds Catalyzed by a Ruthenium(II) Complex Bearing a Chel...Published: 10 February 2011 by Wiley in ChemInform
The title Ru‐complex provides an active catalyst for the hydrogenation of a variety of polar bonds under mild conditions in basic media, reaching a maximum turnover frequency of 17600 h‐1.
In this work we demonstrate the potential of permanent magnet based magnetic resonance sensors to monitor and assess the extent of pore clogging in water filtration systems. The performance of the sensor was tested on artificially clogged gravel substrates and on gravel bed samples from constructed wetlands used to treat wastewater. Data indicate that the spin lattice relaxation time is linearly related to the hydraulic conductivity in such systems. In addition, within biologically active filters we demonstrate the ability to determine the relative ratio of biomass to abiotic solids, a measurement which is not possible using alternative techniques.
ChemInform Abstract: RuHCl(diphosphine)(diamine): Catalyst Precursors for the Stereoselective Hydrogenation of Ketones a...Published: 25 May 2010 by Wiley in ChemInform
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Artificial insemination is a well-established part of modern agricultural practice. A viable semen sample is judged by the total number of spermatozoa (sperm) in the sample and the motility of the sperm. In this paper, we report the development of a reusable measurement cell and electronics for screening semen samples based on the Quartz Crystal Microbalance (QCM) and Universal Frequency to Digital Converter (UFDC-1) to produce a low-cost sensor system. After introducing the semen sample at one end of the measurement cell, sperm swim down a channel before causing a frequency change on the QCM. Data is presented that shows the different frequency changes using a commercial frequency counter caused by porcine semen samples, one two days old and one twenty one days old. Similar data is presented for a motile semen sample measurement using the low-cost UFDC-1.
Development of a Novel Magnetic Resonance Imaging Contrast Agent for Pressure Measurements Using Lipid-Coated Microbubbl...Published: 01 December 2009 by American Scientific Publishers in Journal of Biomedical Nanotechnology
The aim of this study was to prepare gas-filled lipid-coated microbubbles as potential MRI contrast agents for imaging of fluid pressure. Air-filled microbubbles were produced with phospholipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in the presence or absence of cholesterol and/or polyethylene-glycol distearate (PEG-distearate). Microbubbles were also prepared containing a fluorinated phospholipid, perfluoroalkylated glycerol-phosphatidylcholine, F-GPC shells encompassing perfluorohexane-saturated nitrogen gas. These microbubbles were evaluated in terms of physico-chemical characteristics such as size and stability. In parallel to these studies, DSPC microbubbles were also formulated containing nitrogen (N2) gas and compared to air-filled microbubbles. By preventing advection, signal drifts were used to assess their stability. DSPC microbubbles were found to have a drift of 20% signal change per bar of applied pressure in contrast to the F-GPC microbubbles which are considerably more stable with a lower drift of 5% signal change per bar of applied pressure. By increasing the pressure of the system and monitoring the MR signal intensity, the point at which the majority of the microbubbles have been damaged was determined. For the DSPC microbubbles this occurs at 1.3 bar whilst the F-GPC microbubbles withstand pressures up to 2.6 bar. For the comparison between air-filled and N2-filled microbubbles, the MRI sensitivity is assessed by cycling the pressure of the system and monitoring the MR signal intensity. It was found that the sensitivity exhibited by the N2-filled microbubbles remained constant, whilst the air-filled microbubbles demonstrated a continuous drop in sensitivity due to continuous bubble damage.
Subsurface flow wetlands have become a popular technology for the treatment of waste water all over the world. These systems become clogged over time, and must be renovated at great expense. We present a nuclear magnetic resonance sensor which is sufficiently small and inexpensive that several of them could be embedded in a constructed wetland to allow spatially resolved long term continual monitoring of the clogging process. We demonstrate the suitability of this sensor by first measuring NMR of sludge from an operational wetland, and secondly by monitoring the evolution of the fluid's NMR spin lattice relaxation time (T1) during clogging in a model wetland. Measurement of clogging rates in two locations are made and found to be 10.7×10−2min−1 and 4.9×10−3min−1 for regions near the inlet and the centre respectively.