High Magnetic Field Gradient Research Articles

A beam dynamics study for efficient extraction from the VECC K500 superconducting cyclotron

Beam extraction from the K500 superconducting cyclotron is very challenging due to its long extraction path of about 330° with very high magnetic field gradient and low acceptance. The initial attempts of beam extraction showed that the pilot beams could successfully clear only a few magnetic channels. To investigate the causes of the beam loss, magnetic field measurements in different zones of the cyclotron were repeated. The total field has been generated by superposition of the measured field and the numerically computed field of the extraction elements. Based on these data, extensive beam dynamics simulation has been carried and beam distribution at the entry of the extraction path obtained by accelerated orbit calculations. The energy spread due to multi-turn deflector entry has been included in the simulation. The beam envelope along the extraction path as well as the beam transmission efficiency has been determined for different positions of the extraction elements. The radial positions of the extraction elements have been optimized parametrically to compute the maximum transmission efficiency. The present studies have enabled us to successfully extract the pilot beam (N4+) from the cyclotron with beam current of around 20 enA.

One-step detection of oral ulcers and oral cancer derived exosomes on wedge-shaped and high magnetic field gradient mediated chip

Oral ulcers and oral cancer are difficult to be detected not only they are similar symptoms but also lack of diagnosis biomarker. Exosomes are one kind of new liquid biopsy biomarker that can play an important role in disease early-stage diagnosis. Here, oral ulcers and oral cancer, assisted by exosomes, were one-step simultaneous detected on the wedge-shaped and high magnetic field gradient mediated microfluidic chip. For oral ulcers and oral cancer derived exosomes, the detection marker proteins were confirmed by western blot assay, and their antibodies were modified on the surface of magnetic micrometer beads (MBs) and magnetic nanopheres (MNs). Different-sized magnetic material was simultaneously mixed and immunologically captured corresponding exosomes to form an immune complex. With wedge-shaped mediated size separation and high magnetic field gradient controlling capture, the different-size immune complex could be one-step separated and trapped, of which MBs were monolayer arranged in wedge-shaped zone and MNs were trapped in high magnetic field gradient zone. Using high-luminance quantum dots as reporter, the signals of two kinds of exosomes were directly acquired online in the corresponding zones, and could achieve high sensitivity with a detection limit of 8.5 × 104 particles/mL and 4.45 × 105 particles/mL for oral ulcers and oral cancer derived exosomes respectively, and showed excellent anti-interference ability for complex clinical samples. These results indicate that this method may propose new avenues for one-step detection of multiple biomarkers for disease early diagnosis using different-sized magnetic material.

Research on Inductive Oil Contaminant Detection Sensor Based on High Gradient Magnetic Field Structure

Research on Inductive Oil Contaminant Detection Sensor Based on High Gradient Magnetic Field Structure

Innovative technique for patterning Nd–Fe–B arrays and development of a microfluidic device with high trapping efficiency

Trapping/separating bio-entities via magnetic field gradients created a vast number of possibilities to develop biosensors for the early detection of diseases without the need for expensive equipment or physician/lab technicians. Thus, opening a window for at-home disposable rapid test kits. In the scope of the current work, an innovative and cost-effective technique to form well-organized arrays of Nd–Fe–B patterns was successfully developed. High aspect ratio Nd–Fe–B flakes were synthesized by surfactant-assisted ball milling technique. Nd–Fe–B flakes were distributed and patterned into a PDMS matrix by the aforementioned technique. A microfluidic channel was integrated on the fabricated Nd–Fe–B/PDMS patch with a high magnetic field gradient to form a microfluidic device. Fe nanoparticles, suspended in hexane, were flowed through the microfluidic channel, and trapping of the magnetic nanoparticles was observed. More experiments would be needed to quantitatively study efficiency. Ergo, the microfluidic device with high trapping efficiency was developed. The established technique has the potential to outperform the precedents in trapping efficiency, cost, and ease of production. The developed device could be integrated into disposable test kits for the early detection of various diseases.

Accurate calculation of major forces acting on magnetic particles in a high-gradient magnetic field: A 3D finite element analysis

Magnetic agglomeration of magnetic particles under the influence of magnetic field plays a vital role in enhancing the separation of fine magnetic mineral particles. In this study, the major forces acting on weakly magnetic particles and the ratio between forces in high-gradient magnetic separators (HGMS) are investigated. A 3D high-gradient magnetic field based on HGMS was simulated, and the major forces (magnetic force Fm, magnetic agglomeration force Fmm, and gravity G) acting on weakly magnetic particles were calculated in the form of Fm/Fmm, Fm/G by finite element method (FEM). The results show that the value of Fm/Fmm became lower as the increase of magnetic field intensity and the relative permeability of particles, higher as the increase of the magnetic field gradient, the particle size and the distance between particles. However, there was no correlation between the value of Fm/Fmm and the density of the magnetic particles. Furthermore, the value of Fm/G was inversely proportional to the density of the particles and directly proportional to the relative permeability of particles, the magnetic field intensity and magnetic field gradient. Meanwhile, Fm was at least 190 times greater than Fmm in any case and Fm was far bigger than G in most cases, indicating that the magnetic agglomeration is not significant in HGMS and gravity has little effect on high-gradient magnetic separation, and HGMS are destined to be a kind of high-efficiency magnetic separation equipment.

Material manipulation and separation using the horizontal magneto-Archimedes effect

We have studied the manipulation and the separation of substances using the horizontal magneto-Archimedes effect. By ingenerating a high magnetic field gradient in the horizontal direction, it is possible to move the target substance to a designated position in the horizontal direction. We attempted to separate several kinds of valuable metals by applying the horizontal magnetic force to the metals falling vertically into a paramagnetic medium. In order to enhance the magnetic force, we set up the ferromagnetic core array in magnetic fields. According to the trajectory analysis for the metal particles and the magnetic separation experiments, we succeeded in dynamically separating the metal mixture dropped to the vertical direction due to the strong horizontal magnetic force in relatively low magnetic fields. It is expected that this method creates a new device for the separation of substances.

Design and Research of Inductive Oil Pollutant Detection Sensor Based on High Gradient Magnetic Field Structure.

An inductive oil pollutant detection sensor based on a high-gradient magnetic field structure is designed in this paper, which is mainly used for online detection and fault analysis of pollutants in hydraulic and lubricating oil systems. The innovation of the sensor is based on the inductance detection method. Permalloy is embedded in the sensing region of the sensor, so that the detection area generates a high gradient magnetic field to enhance the detection accuracy of the sensor. Compared with traditional inductive sensors, the sensor has a significant improvement in detection accuracy, and the addition of permalloy greatly improves the stability of the sensor’s detection unit structure. The article theoretically analyzes the working principle of the sensor, optimizes the design parameters and structure of the sensor through simulation, determines the best permalloy parameters, and establishes an experimental system for verification. Experimental results show that when a piece of permalloy is added to the sensing unit, the signal-to-noise ratio (SNR) of iron particles is increased by more than 20%, and the signal-to-noise ratio of copper particles is increased by more than 70%. When two pieces of permalloy are added, the signal-to-noise ratio for iron particles is increased by more than 70%, and the SNR for copper particles is increased several times. This method raises the lower limit of detection for ferromagnetic metal particles to 20 μm, and the lower limit for detection of non-ferromagnetic metal particles to 80 μm, which is the higher detection accuracy of the planar coil sensors. This paper provides a new and faster online method for pollutant detection in oil, which is of great significance for diagnosing and monitoring the health of oil in mechanical systems.

MATHEMATICAL AND STATISTICAL MODEL OF CLEANING IN A HIGH-GRADIENT MAGNETIC FIELD OF HYDROGENATED FAT FROM SUSPENDED CATALYST

The introduction specifies the object of the study - hydrogenated fat subjected to purification from suspended nickel-containing catalyst in a high-gradient magnetic field. The nickel-containing catalyst, due to the presence of nickel salts in it, is paramagnetic and can be effectively extracted from hydrated fat in the magnetic field by a method of highly gradient magnetic separation. In the experiment technique the magnetic field strength was not less than 600 kA/m, the gradient not less than (20-30)∙104 kA/m2. Based on the results and their discussion, the analysis of empirical dependencies on each factor basis is carried out separately, as well as the construction of classical types of one-dimensional non-linear regression models for each of them. It is shown that the most statistically reliable are the exponential models. It was found that after purification the content of suspended nickel-containing catalyst in the hydrogenated fat has an inverse proportional dependence on the magnetic field strength, height (length) of the filtration zone and filtration rate. A two-dimensional exponential regression model of the content of the nickel-containing catalyst in the hydrogenated fat in the complex dependence on the rate and height of the filtration zone is built. Based on the experimental data at a certain height of the filtration zone and the selected filtration rate, a mathematical-statistical model of change in the concentration of nickel-containing catalyst depending on the magnetic field strength is made. Using the resulting two-dimensional exponential regression model, it is possible to predict the degree of purification of the salomas from the suspended catalyst depending on the specific tension of the magnetic field and to determine the tension of the magnetic field, at which the concentration of nickel as a result of cleaning will reach an advance value.

Efficient phenol degradation by laccase immobilized on functional magnetic nanoparticles in fixed bed reactor under high-gradient magnetic field.

Enzymatic degradation of emerging contaminants has gained great interest for the past few years. However, free enzyme often incurs high costs in practice. The immobilized laccase on the polyethylenimine (PEI)‐functionalized magnetic nanoparticles (Fe3O4–NH2–PEI–laccase) was fabricated to efficiently degrade phenolic compounds continuously in a newly fixed bed reactor under a high‐gradient magnetic field. The degradation rate of continuous treatment in the bed after 18 h was 2.38 times as high as that of batch treatment after six successive operations with the same treatment duration. Under the optimal conditions of volume fraction of nickel wires mesh, flow rate of phenol solution, phenol concentration, and Fe3O4–NH2–PEI–laccase amount, the degradation rate of phenol kept over 70.30% in 48 h continuous treatment. The fixed bed reactor filled with Fe3O4–NH2–PEI–laccase provided a promising avenue for the continuous biodegradation of phenolic compounds for industrial wastewater in practice.

MEASUREMENT AND MODELLING OF GRADIENT MAGNETIC FIELDS FOR BIO-CHEMICAL SEPARATION PROCESSES

Separation processes are widely used in chemical and biotechnical processes. Especially biomagnetic separation is an important issue among effective separation processes to separate the magnetic micron and submicron particles. It is necessary to establish and determine a high magnetic field or field gradient in the separation cell. However, it is not easy to determine the magnetic field gradient in the working region for different separation in practice. The reason for these difficulties is that the magnetic cells used in biochemical separation have different geometries and there are no simple and useful systems to easily measure these magnetic fields. Two main objectives are aimed in this study. First, a simple measuring device design can measure gradient magnetic fields with high precision of about 0,01mm and, secondly, obtain simple empirical expressions for the magnetic field. A magnetometer with Hall probes that works with the 3D printer principle was designed and tested to measure the magnetic field. Magnetic field changes were measured according to the surface coordinates on the measurement platform or measuring cell. Numerous experimental measurements of gradient magnetic fields generated by permanent magnets have been taken. The results obtained from the studies and results from the proposed empirical models were compared.

Study on association solubilization and inhibition of scale in recirculating cooling water system under S-HGMF

Abstract The present study conducted an investigation on the effect of a superconducting high gradient magnetic field (S-HGMF) on the association solubilization of recirculating cooling water and the crystal form change of scale. The effects of magnetic flux density, flow rate and cycle-index on the solubility of scale-forming ions were investigated, and the effects of viscosity and surface tension on the molecular internal energy and order degree of the circulating water were analyzed. The scale was ground and mixed with water and placed in an S-HGMF system to study the effect of S-HGMF on the crystal form change of CaCO3. The experimental results showed us that S-HGMF could increase the solubility of scale-forming ions. It could enhance the interaction between water molecules by increasing viscosity and reducing surface tension, so as to improve the stability of water quality, reduce ion precipitation, and achieve the effect of scale inhibition. At the same time, it could also change the crystal structure of CaCO3, promote the transformation of calcite to aragonite, and realize the purpose of scale inhibition. In a word, S-HGMF treatment can effectively solve the scaling problem of a recirculating cooling water system, which provides a reference for scale inhibition of recirculating cooling water.

Dedicated NMR sensor to analyze relaxation and diffusion in liquids and its application to characterize lubricants.

A dedicated nuclear magnetic resonance (NMR) sensor was designed for the analysis of liquids. The magnets are arranged in a V shape, creating a spatially dependent magnetic field in the gap. Measurements of samples with diverse diameters are possible underdefined magnetic field gradients at a given position. The magnet thus combines properties of single sided NMR with high static magnetic field gradients and classical time domain (TD) devices with lower to almost zero gradients. The sensor can easily be adapted to the requirements of the considered investigation; probes can be customized. On the example of lubricants and their aging, the added value and applicability of this sensor in quality control are highlighted in this publication. Relaxation and diffusion were measured by Carr-Purcell-Meiboom-Gill (CPMG) while varying the echo time τe and quantified via numerical modeling. Especially, relaxation shows a high sensitivity towards aging of lubricants such as particulate abrasion and changes in molecular dynamics induced, for example, by additive depletion. The applicability of this NMR sensor in quality control is demonstrated on the example of engine and transmission oils as well as of lubrication greases.

Removal of Iron Oxide Scale From Boiler Feed-Water in Thermal Power Plant by Magnetic Separation-Separation Conditions of Oxygenated Treatment Scale

We have been developing the scale removal system utilizing superconducting magnet that can remove iron scale from boiler feed-water in a thermal power plant. The scale removal prevents the plants from the reduction in power generation efficiency. Iron oxide scale consists of the ferromagnetic and the paramagnetic particles, and the optimal separation conditions largely differ depending on the magnetic properties of the particles. So, single separation condition may cause the filter blockage by over capture or inadequate capture. We proposed the two-stage magnetic separation according to the magnetic properties of the aggregates, where the ferromagnetic particles are captured in the 1st stage in low magnetic field and field gradient, and then the paramagnetic ones are captured in the 2nd stage in high magnetic field and field gradient. It was shown that two-stage magnetic separation system for the mixture of ferromagnetic and paramagnetic particles is possible by utilizing one superconducting solenoidal magnet.

An ultrasensitive impedance biosensor for Salmonella detection based on rotating high gradient magnetic separation and cascade reaction signal amplification

An impedance biosensor using rotary magnetic separation and cascade reaction was developed for rapid and ultrasensitive detection of Salmonella typhimurium. First, magnetic nanoparticles (MNPs) modified with anti-Salmonella monoclonal antibodies were injected into a capillary at the presence of a rotary high gradient magnetic field, which was rotated by a stepper motor. Then, a bacterial sample was injected into the capillary and the target bacteria were continuous-flow captured onto the MNPs. After organic-inorganic hybrid nanoflowers were prepared using manganese dioxide (MnO2), glucose oxidase (GOx) and anti-Salmonella polyclonal antibodies (pAbs), they were injected to label the bacteria, resulting in the formation of MNP-bacteria-nanoflower sandwich complexes. Finally, glucose (low conductivity) was injected and oxidized by GOx on the complexes to produce H2O2 (low conductivity) and gluconic acid (high conductivity), leading to impedance decrease. Besides, the produced H2O2 triggered a cascade reduction of MnO2 into Mn2+, leading to further impedance decrease. The impedance changes were measured using an interdigitated microelectrode and used to determine the concentration of target bacteria. This biosensor was able to detect Salmonella ranging from 101 to 106 CFU/mL in 2 h with a low detection limit of 101 CFU/mL and a mean recovery of 100.1% for the spiked chicken samples.

A Ferromagnetic Wear Particle Sensor Based on a Rotational Symmetry High-Gradient Magnetostatic Field

To improve the wear monitoring accuracy of steel tribo-pairs, a ferromagnetic particle sensor that consists of a magnetic loop with two cylindrical magnetic poles and one magnetic housing is proposed. The induction coil is placed inside the magnetic poles to shield against external electromagnetic interference. The air gap is designed to 1 mm between the two magnetic poles, where a rotational symmetric high-gradient static magnetic field will be generated under constant direct current (dc) drive. The sine-wave-like signal of one period will be induced when one ferromagnetic particle flows through the sensor. The working principle of the sensor and the internal magnetic field distribution is explained by establishing a mathematical model and finite element analysis (FEA). Furthermore, the results about the effects of coil length and position show that the output voltage is not sensitive to the axial mounting positions of the induction coil, and a shorter inductive coil produces a larger output voltage. By the oil dynamic monitoring experiment, the sensor can distinguish 13- $\mu \text{m}$ ferromagnetic particles in an oil tube of 10-mm inner diameter. With its high sensitivity to ferromagnetic particles, the sensor is suitable for online wear monitoring of steel tribo-pairs.

Plant Morphofunctional Response to Environmental Changes in Active Fault Zones of the Kurai Ridge (Gorny Altai)

Integrated geological, geophysical, geochemical, and botanical studies in the Kuraika River Valley (Kurai Ridge, Gorny Altai) have revealed sharp changes in the growth environment of blue honeysuckle (Lonicera caerulea) at the conjunction zone of the regional Kubadra and local active faults. A high-gradient magnetic field is accompanied by the increased variability of the concentrations of radionuclides and macro- and micro-elements in soil, an increased mercury content in soil and surface air, and an increased γ-radiation exposure rate. Depending on combinations of geoenvironmental factors, the micropopulations of blue honeysuckle have produced increased or decreased fruit size and seed productivity. The observed tripling of accumulated biologically active phenol compounds in fruits, the simultaneous decrease in their concentration in leaves, and the reduction in the ratio between the content of some polyphenol classes in leaves and fruits are considered a response to the stressing impact of environmental factors associated with active tectonic processes in this area of Altai.

Micromagnetic Manipulators - Ferromagnetic Microwire Systems for Diffusion and Separation of Para and Dia- magnetic Particles in GradientMagnetic Field

Micromagnetic manipulators to control and manage the dynamics of micro and nanoparticles are widely used in medicine, physics, and biology. In this paper, we proposed a number of concepts of targeted use of ferromagnetic microwires for para and dia-magnetic objects manipulation. The microwires are produced in a biocompatible glass shell by Taylor-Ulitovsky method and exhibit tunable magnetic properties. They have the ability to create high gradient magnetic fields due to specific composition of the ferromagnetic core, magnetic domain structure and micron dimensions. For various experimental tasks, the optimal configuration of ferromagnetic microwires in the system and the direction of the wire magnetization are selected. A point trap for paramagnetic particles is formed by an individual wire with an axial magnetization. The wires magnetized along diameter are a source of linearly situated magnetic poles and help to realize a fast redistribution of even weakly paramagnetic particles. Due to a camel-back profile of the magnetic potential, created by a pair of closely spaced wires with orthogonal magnetization they act as effective diamagnetic trapping system. There is also an interesting opportunity to realize a magnetic ratchet using a microwire with a circular domain structure. Thus, the magnetic manipulators based on systems of ferromagnetic microwires make it possible to organize fixation, redistribution and analysis of cell suspensions and magnetic nanoparticles. The biocompatibility of the glass shell of the microwires was demonstrated, hence, the possibility of their further using when working with living objects.

An impedance biosensor based on magnetic nanobead net and MnO2 nanoflowers for rapid and sensitive detection of foodborne bacteria

Screening of pathogenic bacteria in foods is an effective way to prevent foodborne diseases. In this study, an impedance biosensor was developed for rapid and sensitive detection of Salmonella typhimurium using multiple magnetic nanobead (MNB) nets in a ring channel for continuous-flow separation of target bacteria from 10 mL of sample, manganese dioxide nanoflowers (MnO2 NFs) for efficient amplification of biological signal, and an interdigitated microelectrode for sensitive measurement of impedance change. First, the MNBs modified with capture antibodies were vortically injected from outer periphery of this ring channel to form multiple ring MNB nets at specific locations with high gradient magnetic fields. Then, the bacterial sample was continuous-flow injected, resulting in specific capture of target bacteria onto the nets, and the MnO2 NFs modified with detection antibodies were injected to form MNB-bacteria-MnO2 NF complexes. After the complexes were washed with deionized water to remove excessive nanoflowers and residual ions, H2O2 with poor conductivity was injected to reduce MnO2 NFs to conductive Mn2+ at neutral medium, leading to impedance decrease. Finally, impedance change was measured using the microelectrode for quantitative determination of Salmonella. This biosensor was able to separate ~60% of Salmonella from 10 mL of bacterial sample and detect Salmonella with a linear range of 3.0 × 101 to 3.0 × 106 CFU/mL in 1.5 h with lower detection limit of 19 CFU/mL. This biosensor might be further improved with higher sensitivity using a larger volume (100 mL or more) for routine screening of foodborne bacteria without bacterial pre-culture.

Innate Immune Regulation Under Magnetic Fields With Possible Mechanisms and Therapeutic Applications

With the wide applications of magnetic fields (MFs) in medicine, researchers from different disciplines have gained interest in understanding the effect of various types of MFs on living cells and organisms. In this paper, we mainly focus on the immunological and physical aspects of the immune responses and their mechanisms under different types of MFs. Immune cells were slightly affected by low-frequency alternating MFs but were strongly influenced by moderate-intensity MFs and high-gradient MFs (HGMFs). Larger immune cells, such as macrophages, were more sensitive to HGMFs, which biased the cell polarization into the anti-inflammatory M2 phenotype. Subject to the gradient forces of varying directions and strength, the elongated M2 macrophage also remodeled the cytoskeleton with actin polymerization and changed the membrane receptors and ion channel gating. These alterations were very similar to changes caused by the small GTPase RhoA interference in macrophage. Regulation of iron metabolism may also contribute to the MF effects in macrophages. High MFs were found to regulate the iron content in monocyte-/macrophage-derived osteoclasts by affecting the expression of iron-regulation genes. On the other hand, paramagnetic nanoparticles (NPs) combined with external MFs play an important role in T-cell immunity. Paramagnetic NP-coated T-cells can cluster their T-cell receptors (TCRs) by using an external MF, thus increasing the cell–cell contact and communication followed by enhanced tumor killing capacity. The external MF can also guide the adoptively transferred magnetic NP-coated T-cells to their target sites in vivo, thus dramatically increasing the efficiency of cell therapy. Additionally, iron oxide NPs for ferroptosis-based cancer therapy and other MF-related therapeutic applications with obstacles were also addressed. Furthermore, for a profound understanding of the effect of MFs on immune cells, multidisciplinary research involving both experimental research and theoretical modeling is essential.

The localization regime in a nutshell

High diffusion-sensitizing magnetic field gradients have been more and more often applied nowadays to achieve a better characterization of the microstructure. As the resulting spin-echo signal significantly deviates from the conventional Gaussian form, various models have been employed to interpret these deviations and to relate them with the microstructural properties of a sample. In this paper, we argue that the non-Gaussian behavior of the signal is a generic universal feature of the Bloch-Torrey equation. We provide a simple yet rigorous description of the localization regime emerging at high extended gradients and identify its origin as a symmetry breaking at the reflecting boundary. We compare the consequent non-Gaussian signal decay to other diffusion NMR regimes such as slow-diffusion, motional-narrowing and diffusion-diffraction regimes. We emphasize limitations of conventional perturbative techniques and advocate for non-perturbative approaches which may pave a way to new imaging modalities in this field.