Volume Magnetic Susceptibility Research Articles

Ambient temperature 1H/13C NMR spectra of sodium 3-(trimethylsilyl)propane-1-sulfonate (DSS) in D2O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples.

This study aimed to obtain the title spectra and verify the temperature dependence of δDSS of the HOD signal from D2O of the NMR sample. However, the analysis of the collected δX data, extended by the results of other closely related measurements reported in the literature, provided important guidelines for performing routine 1H/13C NMR spectra in aqueous solvents externally referenced to neat liquid TMS contained in a coaxial capillary. Therefore, it is recommended that the previously proposed correction of δX data thus determined, which is mainly due to the difference in volume magnetic susceptibility χv between the sample and the external standard used, usually called the bulk magnetic susceptibility (BMS) correction, has been increased by +0.05 ppm (7%). The new value of this correction, +0.73 ppm, based on NMR experiments carried out at a standard temperature of 25°C, was confirmed in a classical approach using critically reviewed χm, χM, and ρ data for TMS, D2O, and H2O. The BMS correction for H2O solutions is +0.75 ppm. Important issues concerning magnetic susceptibility measurements for D2O and H2O, coaxial bulb-ended inserts, and the geometry of two-tube NMR cells (shape factor αav) are also critically discussed here, partly from a historical perspective.

Magnetic and Geochemical Properties of Zagreb City Area Soils

This study was performed to derive the first insight into the distribution of low-field volume magnetic susceptibility (MS) throughout Zagreb city, based on in situ field measurements. The most interesting locations were selected for soil sampling and their geochemical contents were determined using ICP-OES. A geostatistical approach was applied to the MS and geochemical results. A median of 0.245 × 10−3 SI units was proposed as the average MS value in Zagreb. The mean concentrations of heavy metals in Zagreb’s soils (in µg/g) are Pb (36.82), Zn (87.77), Cu (30.84), Cd (0.66), Cr (29.04), Co (11.89), and Ni (28.40), and these measurements are relatively low in comparison to the Croatian legislation and the European and world average. Boxplot analyses demonstrate that 45% of the studied elements do not feature any anomalies, while most of the remaining elements indicate only one weak anomaly located at the same site as the MS anomalies. Our statistical analysis found significant correlations between MS and the following elements: Cd, Co, Fe, Mn, Na, Pb, Sb, and Zn. In situ MS measurements proved to be an efficient tool for the initial screening of large areas with elevated concentrations of heavy elements, enabling the cheap and fast assessment of the state of the environment.

Modeling the response of a field probe for nondestructive measurements of the magnetic susceptibility of soils

AbstractNondestructive volume magnetic susceptibility measurements (MS) from the surface do not provide information about the depth distribution of a magnetic material or about the amount of magnetic material. We have developed a model that can be used to predict the volume magnetic susceptibility from the surface for a given (known or hypothesized) stratification of the magnetic layers in the soil profile. The measurements were performed with the MS2D Bartington sensor. The antenna signal from the MS2D probe decreases rapidly with depth. We show that the relative decrease in MS depends not only on the concentration of the magnetic tracer, but also on the distribution of the magnetic tracer in the soil profile. The decrease in sensitivity was fitted with a double exponential function. The function was implemented in a newly developed MagHut model. The MagHut model is a tool that can be used for forward modeling of the volume magnetic susceptibility when the tracer distribution in the soil profile is known. The model was successfully calibrated and validated with the measured data and with data from the literature. The Nash–Sutcliffe coefficients for goodness of fit were above 0.99 in all cases. MagHut can help interpret MS mapping results or it can be used to optimize amount and placement of the magnetic tracer for soil erosion experiments. However, the MagHut tool is only limited to the top 10 cm of the soil profile and cannot replace, but only complement, the standard procedure of occasional soil profile sampling and laboratory mass MS measurements.

Study of the Diamagnetic Properties of Liquid Polydimethylsiloxane (PDMS) with the Moses Effect

The relationship between the magnetic susceptibility and degree of polymerization of liquid polydimethylsiloxane (PDMS) was studied experimentally. The magnetic susceptibility of the liquid PDMS was established with the Moses effect, i.e., study of the shape of the near-surface well (the well created near the surface-vapor interface) created in the liquid by a permanent magnetic field. The study of the shape of the near-surface well was carried out under experimental registration of the laser beam reflected from the PDMS/air interface. The broad range of available molecular weights of PDMS made it suitable for the study. The diamagnetic susceptibility, of PDMS was measured for a broad range of molecular weights. The plot of magnetic susceptibility, χ, against the number of repeating units in the chain, n, was linear. The result was compared with the magnetic susceptibility predicted by the Pascal law. The volume magnetic susceptibility of the liquid PDMS was established as = (−7.77 ± 0.06) · 10−6. The magnetic susceptibility of the PDMS monomer was established as χexp (n = 1) = (60.3 ± 0.32) · 10−11, which is in a satisfactory agreement with the Pascal empirical rule.

Evaluation of indoor/outdoor urban air pollution by magnetic parameters; preliminary study

The paper presents a comparison of outdoor and indoor air pollution by means of magnetic properties of dust gathered outdoors and indoors on air filters. Outdoor dust (particulate matter smaller than 10 μm, PM10) was collected by means of a PM sampler that was placed in the yard of the building of the Institute of Geophysics, Polish Academy of Sciences (IG PAS), in Warsaw, Poland. Indoor dust samples were collected with the same type of PM sampler, placed inside this building. The magnetic methods were applied for the estimation of concentration and magnetic mineralogy of the magnetic particles present in PM. Magnetic measurements, such as low and high-temperature dependence of volume magnetic susceptibility κ(T), hysteresis parameters, and frequency dependence of mass magnetic susceptibility χfd show that outdoor and indoor PM contain ultra-fine-grained magnetite-like minerals, particularly in a size range < 30 nm. This pointed to the common outdoor sources of pollution intruding inside the building through windows, ventilation systems, and partly carried on dresses by people. The mass of PM10 collected outdoors is of the same range as the mass of PM10 from inside the building. The mass susceptibility of indoor filters, however, is about 1/3 of the mass susceptibility of outdoor filters. The relationship between volume susceptibility and mass indicates a relatively homogenous composition of indoor dust but a varying composition of outdoor dust, with a variable influx of nonmagnetic exogenous particles.

Development of Novel Magnetic Separation for Paramagnetic Particles Using the Selection Tube

Generally, in order to control and separate of paramagnetic substances by magnetic force, a superconducting high-gradient magnetic separation system applied magnetic field of about 5 T over is required. In this study, we aim to apply a low magnetic field for magnetic separation of paramagnetic substances. We proposed the novel separation method, which is applying a magnetic field to the selection tube, aiming for more precise and easier separation than the conventional High Gradient Magnetic Separation System (HGMS). Selection tube can separate particle mixture into each kinds of particles by the balance of drag force, buoyancy and gravity depending on flow velocity, particle size, shape and specific weight. Since the particles are apparent weightless state, they can be captured with a relatively small magnetic force. Firstly, we showed the effectiveness of Open-Gradient Magnetic Separation (OGMS: applied maximum magnetic flux density 1.3 T) under the selection tube with using colored glass imitated target substance. The experimental results were found to shows good separation efficiency. Eventually, we tested the HGMS obtained by improving the novel magnetic separation method, where a low magnetic field applied (maximum magnetic flux density 0.5 T) is applied to magnetic filters (wire diameter ϕ 0.8mm, 15mesh, SUS430) installed in the selection tube. The effective separation of paramagnetic glass (volume magnetic susceptibility: +3.17×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> ) was performed successfully with the combination of the selection tube and the HGMS applied low magnetic field.

Room-temperature atomic layer deposition of iron oxide using plasma excited humidified argon

Room-temperature atomic layer deposition (RT-ALD) of iron oxide is developed with a precursor of bis(N, N′-diisopropyl-propionamidinate)iron [(DIPPA)2Fe] and plasma excited humidified Ar. Saturated conditions of (DIPPA)2Fe and plasma excited humidified Ar exposures at room temperature (23–25 °C) are investigated by in situ IR absorption spectroscopy for finding the RT-ALD process condition. Using the designated process, the growth per cycle of the iron oxide RT-ALD is confirmed as 0.15 nm/cycle based on the film thicknesses measured by the spectroscopic ellipsometer. The x-ray photoelectron spectroscopy suggests that the stoichiometry of the deposited iron oxide is closed to that of Fe2O3. The grown film is composed of partly crystallized iron oxides, confirmed by cross-sectional TEM and AFM. The RT deposited iron oxide exhibits a magnetic volume susceptibility of 1.52, which implies the applicability of the present coating for magnetic drug delivery. We discuss the surface reaction with the IR absorption spectroscopy and the quartz crystal microbalance. The (DIPPA)2Fe molecule is suggested to adsorb on the Fe2O3 surface with mixed first- and second-order reactions at RT. It is also suggested that amidinate ligands in (DIPPA)2Fe are released in the course of the adsorption and the remaining ligands are oxidized by the plasma excited humidified Ar. The RT iron oxide deposition is demonstrated, and the reaction mechanism of room-temperature ALD is discussed in this paper.

Microstructure and mechanical properties of MRI-compatible Zr-9Nb-3Sn alloy fabricated by a laser powder bed fusion process

We investigated the microstructure, mechanical properties, and magnetic susceptibility of novel metastable β-type Zr-9Nb-3Sn alloy builds fabricated using a laser powder bed fusion (L-PBF) process. In addition to the dominating β and small amount of ω phases, a unique needle-like β´phase with a body-centered tetragonal crystal structure was formed due to the high thermal stress during the L-PBF process. The alloy builds fabricated at a higher energy density showed a〈100〉 preferential orientation parallel to the building direction, whereas random crystallographic orientation was observed in those fabricated at a lower energy density. Compared with the randomly oriented build, Young’s modulus of the oriented one was lower at 55 GPa, the tensile elongation was higher at 16%, and the tensile strength was higher at 796 MPa. The Zr-9Nb-3Sn alloy builds possess a higher yield and tensile strength compared to their as-cast counterparts. Moreover, the volume magnetic susceptibility of the alloy builds was two-thirds that of commonly used CP-Ti and Ti-6Al-4V. The combination of low magnetic susceptibility, low Young’s modulus, and moderate ductility make the Zr-9Nb-3Sn alloy a potential candidate for biomedical devices used in magnetic resonance imaging.

Delineation of sulfide mineralization over a part of western margin of greenstone belt of the Dhanjori Basin, Singhbhum Craton from petrophysical, petrographic and geophysical studies

The Archean greenstone belt occupying the Dhanjori basin is a potential target for exploring resources of various precious metals and sulfide minerals like other Precambrian greenstone belts. Thick alluvium cover and limited outcrops in the survey area pose challenges in mineral exploration strategies. This work presents an integrated study of petrophysics, petrography and geophysics (gravity and magnetic survey) over an identified conductor in the western margin of the Dhanjori basin, which aims to delineate anomalous sulfide-bearing zones. The present analysis of petrophysical parameters (bulk density, and volume magnetic susceptibility) of various litho-units including dolerite, metabasalt, magnetite, chert and metasediments (quartzite and quartz pebble conglomerate (QPC)) indicate the occurrences of sulfide minerals. Petrographic studies of the smoky and fuchsitic quartzites also suggest sulfide mineral phases (chalcopyrite, and pyrite). EPMA studies on these metasediments reveal the presence of sulfide minerals (pyrite, chalcopyrite, millerite, bornite and pyrrhotite) and sulfosalts (gersdorffite, and cobaltite), along with traces of gold and silver. The 3D inversion of gravity and magnetic data identified significant geophysical signatures corresponding to possible subsurface sulfide mineralization and have helped in the reduction of the target area. This work also demonstrates the utility of integrated investigations in identifying deep-seated mineralization, which may be helpful in exploring analogous prospective Precambrian greenstone belts.

Dual-phase Au-Pt alloys free from magnetic susceptibility artifacts in magnetic resonance imaging

PurposeMagnetic resonance imaging (MRI) devices are frequently used in image-based diagnosis. In the case of large artifacts, which are generated in magnetic resonance (MR) images when magnetic materials, such as metals, are present in the body, these devices are less useful. This study aimed to develop a dual-phase Au-Pt alloy that does not generate artifacts in MR images and has high workability to prepare medical devices. Materials and methodsA processing method to produce a dual-phase Au-Pt alloy was established, and the magnetic susceptibility and artifacts of different alloy compositions were determined using a SQUID (superconducting quantum interference device) flux meter and a 1.5 T-MRI system. The crystallographic phases of the prepared alloy samples were identified using X-ray diffraction. Sample cross-sections were observed using a metallurgical microscope. Furthermore, a thinning test was conducted to examine alloy workability. ResultsDual-phase Au-Pt alloys Au70Pt30 and Au67Pt33—the former heat-treated at 800 and 850 °C and the latter heat-treated at 900 °C—generated minimal artifacts when imaged in a 1.5 T-MRI system. Their volume magnetic susceptibility increased as the heat-treatment temperature decreased. The alloy surfaces were observed to be uniform. Moreover, the workability of the dual-phase alloy was considerably better than that of the single-phase alloy. ConclusionVolume magnetic susceptibility could be controlled by changing the composition and processing temperature of the Au-Pt alloys. Dual-phase Au-Pt alloys those do not generate magnetic susceptibility artifacts in MRI images and have good workability could be prepared. The alloys are expected to be used in the preparation of various implantable medical devices.

Quantification of pedogenic particles masked by geogenic magnetic fraction

Pedogenic magnetic fraction in soils is attributed to fine-grained particles, i.e. superparamagnetic grains. In the case of a strongly magnetic geogenic fraction, pedogenic magnetic contribution is hard to detect. To the best of our knowledge, detailed research into the masking of pedogenic superparamagnetic grains and quantification of this effect has not yet been carried out. The principal aim of our research is to quantify the influence of coarse-grained ferrimagnetic fraction on the detection of the superparamagnetic grains. In order to describe the masking phenomenon, volume and frequency-dependent magnetic susceptibility were determined on a set of laboratory prepared samples composed of natural substances: a diamagnetic quartz matrix, detrital coarse-grained ferrimagnetic crystals from alkaline and ultra-alkaline igneous rocks, and superparamagnetic soil concretions formed in the Haplic Cambisol. Mineralogy, concentration, type and grain size of the tested material were described by parameters of environmental magnetism. The magnetic parameters distinguish both geogenic multidomain and pedogenic superparamagnetic grains. The magnetic signal of the superparamagnetic grains is gradually masked by the increasing proportion of multidomain grains of magnetite/maghemite. The experiment clearly describes the masking effect and brings new insight to studies dealing with strongly magnetic soils of natural and/or highly contaminated origin as a tool for estimation of superparamagnetic pedogenic contribution.

Magnetic characterization of paramagnetic reagents by particle tracking velocimetry.

Magnetic particle characterization determines the quality of magnetic particles and is of great importance in particle technology, drug delivery, cell separation, in vivo diagnostics, and other biomedical applications. The quality of the sample depends on the particle size, intrinsic magnetic properties of the particles, and the uniformity of these properties. A commercial particle tracking velocimeter was used to record and capture dark field images of particle trajectories in an applied isodynamic magnetic field. The calibrated particle size, magnetophoretic mobility, and additional image data were collected for each magnetic bead imaged. Using twenty-one different de-identified calibration beads and transmission electron microscopy to validate the vendor-reported particle size enabled the estimation of intrinsic magnetic properties, namely, apparent magnetic susceptibility and saturation magnetization, of individual paramagnetic particles. The distributions of volume magnetic susceptibility based on the magnetophoretic mobility and size of the particle for different magnetic beads were determined and displayed as two-parameter distributions. The measured apparent susceptibility and saturation magnetization were found to be directly proportional to the percentage of iron oxide in the reagent particles.

Laboratory and field measurement of magnetic susceptibility of Japanese agricultural soils for rapid soil assessment

Measuring volume magnetic susceptibility (κ) of soil allows rapid soil assessment. In this study, we measured the κ value of agricultural surface soils in Japan at national and farm scales in order to evaluate the scale-dependent relationship between soil κ and other soil properties and to examine the repeatability of the κ value measured in the laboratory and in the field. A handheld field sensor was used to measure two sample sets: (1) 164 samples collected throughout Japan (national scale), and (2) 246 samples collected from paddy fields in Takatsuki and 117 (39 sites × 3 times) samples collected from paddy fields in Mifune (farm scale). Laboratory measurements showed that the coefficients of variation of soil κ were 112% for the national scale samples, 13% for the Takatsuki samples, and 33–37% for the Mifune samples. The large variation at the national scale was due to several positive outliers, which were classified as Vitric or Silandic Andosols by the WRB classification. Repeated measurement of samples enabled estimation of the within-sample variation in κ, and the data was considered unreliable if the coefficient of variation exceeded 10%. The correlation analysis using the reliable data indicated that at the national scale, the κ value was most positively correlated with structural Fe (total Fe minus Fed) followed by Alo and the andic properties (Alo + 1/2Feo). In contrast, for the Mifune samples collected at the farm scale, the κ value was most positively correlated with sand content followed by K saturation percentage. Field measurements of soil κ at the 39 Mifune sites indicated that the coefficients of variation of κ at the same site were almost all below 10%. The within-site variations were due probably to the incomplete contact between the soil surface and the sensor. Our results suggest that measuring κ of agricultural surface soils in Japan can help to distinguish Vitric or Silandic Andosols from other soils, and to estimate the κ-related soil properties at the farm and national scales.

Effects of ferromagnetic & carbon-fibre Z-Pins on the magnetic properties of composites

This paper investigates for the first time the effects of Z-pins on the magnetic properties of composite laminates. In-plane and out-of-plane M-H curves of IM7/8552 laminates with and without Z-pins have been characterised by an MPMS3 SQUID magnetometer. Two kinds of pin materials (T300/BMI composite and ferromagnetic Ni/Fe alloy) have been studied at three different volume fractions (nominally 0.5%, 2% and 4%). The unpinned and carbon-fibre pinned laminates were found to be diamagnetic. The carbon-fibre pin had no significant influence on the global magnetic properties of the laminates. The Ni/Fe alloy pin increased the laminate linear-part magnetic volume susceptibility up to 1.87 and 0.13 for the out-of-plane and in-plane directions, respectively. Numerical modelling has been conducted to support the investigation of the effect of the pin volume fraction on the overall magnetic susceptibility and saturation magnetisation. The laminate out-of-plane susceptibility exhibits a nonlinear behaviour dependent on pin volume fraction, due to interactions between adjacent pins. The saturation magnetisation is proportional to the pin volume fraction and independent of field direction.

Characteristics of the Density and Magnetic Susceptibility of Rocks in Northern Borneo and their Constraints on the Lithologic Identification of the Mesozoic Rocks in the Southern South China Sea

AbstractBased on the volume magnetic susceptibility and specific gravity measurements and mineral and lithologic identification results for 540 samples, the rock type, density, and magnetic susceptibility of rocks from northern Borneo were analyzed, and the applicability of gravity and magnetic data to the lithologic identification of the Mesozoic strata in the southern South China Sea was assessed accordingly. The results show that there are 3 types and 25 subtypes of rocks in northern Borneo, mainly intermediate‐mafic igneous rocks and exogenous clastic sedimentary rocks, with small amounts of endogenous sedimentary rocks, felsic igneous rocks, and metamorphic rocks. The rocks that are very strongly–strongly magnetic and have high–medium densities are mostly igneous rocks, tuffaceous sandstones, and their metamorphic equivalents. The rocks that are weakly magnetic‐non‐magnetic and have medium–very low densities are mostly conglomerates, sandstones, siltstones, mudstones, and coal. The rocks that are weakly magnetic‐diamagnetic and have high‐medium densities are mostly limestones and siliceous rocks. The Cenozoic rocks are characterized by low densities and medium susceptibilities; the Mesozoic rocks are characterized by medium densities and medium–high susceptibilities; and the pre‐Mesozoic rocks are characterized by high densities and low magnetism. Based on these results and the distribution characteristics of the various rock types, it was found that the pre‐Mesozoic rocks produce weak regional gravity anomalies; the Mesozoic sedimentary rocks produce negative regional gravity anomalies; whereas the Mesozoic igneous rocks produce positive regional gravity anomalies; and the Cenozoic igneous rocks produce positive regional gravity anomalies. The regional high magnetic anomalies in the southern part of the South China Sea originate from the Mesozoic mafic igneous rocks and their metamorphic equivalents; and the regional medium magnetic anomalies may be produced by the felsic igneous rocks and their metamorphic equivalents. Accordingly, the identification of the Mesozoic lithology in the southern South China Sea shows that the Mesozoic sedimentary rocks are distributed over a large area of the southern South China Sea. Thus, it is concluded that the Mesozoic strata in this area have the potential for oil and gas exploration.

Магнитная восприимчивость мерзлотных лугово-чернозёмных почв Центральной Якутии

Magnetic susceptibility was studied for the first time, as well as geographical and genetic features of the formation of properties and composition of permafrost meadowchernozem soils in Central Yakutia, depending on the conditions of soil formation and anthropogenic impact. A total of 11 soil sections were studied, with 6 soils developing under natural vegetation, and 5 under various agricultural lands. Various soil research methods, such as comparative geographical, profile-genetic, and comparative-analytical, were used in the course of this work, and the composition and properties of soils were determined using generally accepted methods. The volume magnetic susceptibility (VMS) was determined using a smallsized magnetic susceptibility meter KM-7, which is an improved version of the kt- 6 kappameter. The value of the specific magnetic susceptibility (SMS) was obtained by dividing the VMS value by the soil density p (expressed in kg/m3), χ = χ/p. It is shown that the properties of the studied soils differed significantly depending on the conditions of soil formation, as well as on the nature and level of anthropogenic impact. Also, the values of VMS and SMS of these soils of natural landscapes of Central Yakutia changed significantly, making up 31.4-138.9 Si units, respectively. 31.4-102.3ꞏ10-8 m3/kg. Even more variable values of VMS and SMS were observed in anthropogenic-modified analogs of the studied soils, where the values of VMS were 31.5-267.8 Si units, and those of SMS– 30.6-199.8ꞏ10-8 m3/kg. The magnetic profiles of the studied soils, which are characterized by the ratio χ/χc in the soils of natural landscapes corresponded to a more or less uniform type of distribution, where the values of the ratio χ/χc were 0.7-1.3, while in the studied soils of anthropogenic landscapes the values of these relations significantly narrow down and expanded to 0.2-2.0. This cardinally distinguishes the magnetic profiles of the studied permafrost meadow-chernozem soils from the corresponding chernozem soils of other non-permafrost regions of Russia, where accumulative types of magnetic profiles are usually formed, and the ratio χ/χc in the surface humus horizons is about 1,5 or even more.

Influence of Halogen Ions on Electrical, Magnetic and Shielding Properties of Some B2O3- V2O5- Na2O Glasses

Some sodium boro-vanadate glasses containing various halogen ions (chlorine, bromine and iodine) were prepared. These glasses were characterized by measuring the experimental densities, dc conductivities and volume-magnetic susceptibilities. Then the empirical densities, experimental and empirical molar volume values, electrical activation energies, mass- and molar-magnetic susceptibilities as well as the total mass attenuation coefficients of all glasses were calculated. The gradual increase in halogen ions act to decrease experimental density from 2.45 to 2.13 g/cm3, while it acts to increase the molar volume. It was found that, the activation energy decreased around 0.3 eV as the halogen content was increased, it decreased also ongoing from chlorine to iodine that can be ascribed to the differences in ionic radii of halogen ions, and this was confirmed by the molar volume. It was supposed that the increase in the paramagnetic character of the studied glasses with the increase of halogen content may be due to the formation of VXO3 groups. Also, the magnetic properties were found to increase as the ionic radius of the introduced halogen ions increased, and this can be attributed to the increase in the internal vacancies through the network. Correlations were established between both the activation energy and molar susceptibility with molar volume. According to the results of the mass attenuation coefficients, it was found that, the sample contains 25 mol% NaI is the best one that can be used as -ray attenuator, but only at gamma-ray energies up to 356 keV.

Mechanical resonator to measure magnetic susceptibility of structurally intact bone

Magnetic susceptibility of structurally intact bone may play a role in low frequency (below 10 kHz), low field (below 10 mT amplitude) pulsed electromagnetic field (LF PEMF) treatment of fracture non-unions and an adjunct to cervical fusion surgery, approved by the U.S Food and Drug Administration (FDA). The aim of this study was to determine if a difference in PEMF treatment results in measurable differences in the bone magnetic susceptibility using a model of structurally intact rat vertebrae. We measured bone volume magnetic susceptibility by a custom built mechanical resonator comprising a diametrically-polarized NdFeB permanent dipole magnet cylinder (25.4 × 25.4 mm, height by diameter) rotated about its axis by a stepper motor at even intervals from 53 to 63 RPM, acting as a source of a local, oscillating magnetic field (mean field of 95 mT, gradient of 12 T/m) on an intact laboratory rat lumbar vertebrae (n = 21, from tissue repository from past studies on LF PEMF treatment in vivo) suspended 26.0 mm from magnet axis on a thin line of 80 mm nominal length forming a pendulum of nominal eigenfrequency of 100 Hz. The vertebra motion was captured by a video camera and the geometrical center of its 2D image motion was analyzed by ImagePro® and MATLAB® routines. The amplitude of bone oscillations (at twice the angular frequency of the rotating magnet) showed a characteristic pattern of resonance with the magnet rotational frequency. The amplitude maximum agreed with that calculated from a model of forced, damped harmonic oscillator and the diamagnetic tension force acting on bone. The calculated mean volume magnetic susceptibility (SI) of -was on the order of magnitude of literature value (|χ|≈10-5). The results point to the bone site-specific aspect of LF PEMF therapy and provide experimental and theoretical basis for a novel, rational method of designing next generation of effective LF PEMF therapies.

Technogenic contamination or geogenic enrichment in Regosols and Leptosols? Magnetic and geochemical imprints on topsoil horizons

Determination of the origin (geogenic or technogenic) of magnetic and geochemical imprints in soils and the role of weathering processes is crucial for the assessment of relationship between technogenic magnetic particles (TMPs) and potentially toxic elements (PTEs), iron and manganese. Our primary aim is to distinguish the most reliable methods for the appropriate interpretation of measured parameters strictly attributed to particular soil horizons (including bedrock), which is not yet very common in soil magnetometry. We examined six soil profiles developed from/on five different rock types (sedimentary and igneous rocks). The magnetic parameters reflect the concentration, type and grain size of the magnetic particles. Geochemical analysis consists of the determination of PTEs (Co, Cr, Cu, Ni, Pb and Zn), Fe and Mn. Quantification of soil contamination is based on calculating the index of geoaccumulation and enrichment factors. Interpretation is based on plots and magnetic and geochemical data, evaluated by principal component analysis for particular soil horizons. The results show that the volume magnetic susceptibility of the topsoil (mineral horizon Ah) in areas where the soil is developed from strongly magnetic bedrock is primarily influenced by geogenic magnetic particles (GMPs) derived from weathering processes. In cases of magnetic susceptibility determined on organic subhorizons (Oea or Oa), the magnetic parameters indicate the occurrence of TMPs. Moreover, the ratios of saturation isothermal remanent magnetization over magnetic susceptibility, and magnetic susceptibility over iron content help in distinguishing both geogenic and technogenic magnetic contributions. The variations of magnetic susceptibility and iron concentration reflect the presence of the strongly magnetic fraction in total soil iron content. Lead and zinc exhibit unambiguous technogenic influx into topsoil horizons. We conclude that the technogenic contamination dominates over geogenic enrichment in soils developed from/on weakly magnetic bedrock, but also strongly magnetic bedrock (without weathering effects).

Magnetic Susceptibility-Based Protein Detection Using Magnetic Levitation.

Magnetic levitation, which is a magnetic phenomenon of levitating particles suspended in a paramagnetic liquid under a nonuniform magnetic field, is a powerful tool for determining densities and magnetic properties of micro- and nanoparticles. The levitation height of particles in the magnetic field depends on the magnetic susceptibility and density difference between the object and the surrounding liquid. Here, we developed a magnetic susceptibility-based protein detection scheme in a low-cost and miniaturized magnetic levitation setup consisting of two opposing magnets to create a gradient of a magnetic field, a glass capillary channel to retain the sample, and two side mirrors to monitor inside the channel. The method includes the use of polymeric microspheres as mobile assay surfaces and magnetic nanoparticles as labels. The assay was realized by capturing the target protein to the polymer microspheres. Then, magnetic nanoparticles were attached onto the resulting microsphere-protein complex, creating a significant difference in the magnetic properties of polymer microspheres compared to those without protein. The change in the magnetic properties caused a change in the levitation height of the microspheres. The levitation heights and their distribution were then correlated to the amount of target proteins. The method enabled a detection limit of ∼110 fg/mL biotinylated bovine serum albumin in serum. With the sandwich immunoassay developed for mouse immunoglobulin G, detection limits of 1.5 ng/mL and >10 ng/mL were achieved in buffer and serum, respectively. This approach sensed the minute changes in the volume magnetic susceptibility of the microspheres with a resolution of 4.2 × 10-8 per 1 μm levitation height change.