Magnetic Susceptibility Values Research Articles

Simultaneous Quantitative Susceptibility Mapping of Articular Cartilage and Cortical Bone of Human Knee Joint Using Ultrashort Echo Time Sequences.

BackgroundIt is of great clinical importance to assess the microstructure of the articular cartilage and cortical bone of the human knee joint. While quantitative susceptibility mapping (QSM) is a promising tool for investigating the knee joint, however, previous QSM studies using conventional gradient recalled echo sequences or ultrashort echo time (UTE) sequences only focused on mapping the magnetic susceptibility of the articular cartilage or cortical bone, respectively. Simultaneously mapping the underlying susceptibilities of the articular cartilage and cortical bone of human in vivo has not been explored and reported.MethodThree-dimensional multi-echo radial UTE sequences with the shortest TE of 0.07 msec and computed tomography (CT) were performed on the bilateral knee joints of five healthy volunteers for this prospective study. UTE-QSM was reconstructed from the local field map after water-fat separation and background field removal. Spearman’s correlation analysis was used to explore the relationship between the magnetic susceptibility and CT values in 158 representative regions of interest of cortical bone.ResultThe susceptibility properties of the articular cartilage and cortical bone were successfully quantified by UTE-QSM. The laminar structure of articular cartilage was characterized by the difference of susceptibility value in each layer. Susceptibility was mostly diamagnetic in cortical bone. A significant negative correlation (r=−0.43, p<0.001) between the susceptibility value and CT value in cortical bone was observed.ConclusionUTE-QSM enables simultaneous susceptibility mapping of the articular cartilage and cortical bone of human in vivo. Good association between susceptibility and CT values in cortical bone suggests the potential of UTE-QSM for bone mapping for further clinical application.

Automated Segmentation of Midbrain Structures in High-Resolution Susceptibility Maps Based on Convolutional Neural Network and Transfer Learning.

BackgroundAccurate delineation of the midbrain nuclei, the red nucleus (RN), substantia nigra (SN) and subthalamic nucleus (STN), is important in neuroimaging studies of neurodegenerative and other diseases. This study aims to segment midbrain structures in high-resolution susceptibility maps using a method based on a convolutional neural network (CNN).MethodsThe susceptibility maps of 75 subjects were acquired with a voxel size of 0.83 × 0.83 × 0.80 mm3 on a 3T MRI system to distinguish the RN, SN, and STN. A deeply supervised attention U-net was pre-trained with a dataset of 100 subjects containing susceptibility maps with a voxel size of 0.63 × 0.63 × 2.00 mm3 to provide initial weights for the target network. Five-fold cross-validation over the training cohort was used for all the models’ training and selection. The same test cohort was used for the final evaluation of all the models. Dice coefficients were used to assess spatial overlap agreement between manual delineations (ground truth) and automated segmentation. Volume and magnetic susceptibility values in the nuclei extracted with automated CNN delineation were compared to those extracted by manual tracing. Consistencies of volume and magnetic susceptibility values by different extraction strategies were assessed by Pearson correlation coefficients and Bland-Altman analyses.ResultsThe automated CNN segmentation method achieved mean Dice scores of 0.903, 0.864, and 0.777 for the RN, SN, and STN, respectively. There were no significant differences between the achieved Dice scores and the inter-rater Dice scores (p > 0.05 for each nucleus). The overall volume and magnetic susceptibility values of the nuclei extracted by the automatic CNN method were significantly correlated with those by manual delineation (p < 0.01).ConclusionMidbrain structures can be precisely segmented in high-resolution susceptibility maps using a CNN-based method.

Assessing the impact of vehicular particulate matter on cultural heritage by magnetic biomonitoring at Villa Farnesina in Rome, Italy

Magnetic biomonitoring methodologies were applied at Villa Farnesina, Rome, a masterpiece of the Italian Renaissance, with loggias frescoed by renowned artists such as Raffaello Sanzio. Plant leaves were sampled in September and December 2020 and lichen transplants were exposed from October 2020 to early January 2021 at increasing distances from the main trafficked road, Lungotevere Farnesina, introducing an outdoor vs. indoor mixed sampling design aimed at assessing the impact of vehicular particulate matter (PM) on the Villa Loggias. The magnetic properties of leaves and lichens - inferred from magnetic susceptibility values, hysteresis loops and first order reversal curves - showed that the bioaccumulation of magnetite-like particles, associated with trace metals such as Cu, Ba and Sb, decreased exponentially with the distance from the road, and was mainly linked to metallic emission from vehicle brake abrasion. For the frescoed Halls, ca. 30 m from the road, the exposure to traffic-related emissions was very limited or negligible. Tree and shrub leaves of the Lungotevere and of the Villa's Gardens intercepted much traffic-derived PM, thus being able to protect the indoor cultural heritage and providing an essential conservation service. It is concluded that the joint use of magnetic and chemical analyses can profitably be used for evaluating the impact of particulate pollution on cultural heritage within complex metropolitan contexts as a preventive conservation measure.

Siderite occurrence in petroleum systems and its potential as a hydrocarbon-migration proxy: A case study of the Catcher Area Development and the Bittern area, UK North Sea

We report a detailed magnetic study of Tertiary sandstone cores from the Bittern field, West Central Graben, and Catcher Area Development (CAD), West Central Shelf, UK North Sea that identified siderite as a potential magnetic proxy for the differentiation of vertical and lateral hydrocarbon migration. Magnetic hysteresis experiments revealed increased presence of paramagnetic minerals in the oil-stained sandstones of the fields compared to the nearby dry Tertiary (unstained) sandstone of offset wells. Within the oil-stained sandstones, the paramagnetic proportion is highly variant, with low and high paramagnetic sections present. Detailed experiments including thermomagnetometry between 10 K and 900 K and XRD analysis, combined with Mössbauer spectroscopy confirmed that this increase in paramagnetic response was primarily due to the formation of siderite. An increase in the quantity of paramagnetic clays and occasionally pyrite also contributed to the increased response. Siderite and iron sulphides have been interpreted to form during hydrocarbon migration and potentially oil biodegradation. We propose that hydrocarbon migration pathways may be indicated by the distribution of siderite. We argue that as hydrocarbons migrate vertically and the equilibrium partial pressure of CO2 with the environment reduces, essential HCO3− is produced which reacts with available Fe2+ to form siderite if all the other diagenetic requirements for its formation are met. The distribution of siderite and magnetic susceptibility values along the oil-stained layer provides a tool for the determination of the migration pathways in low sulphur hydrocarbon environments containing reactive iron.

Magnetic Fabrics and Petrography of Rocksalts Reveal Preferred Orientation of Anhydrites within a Halite Matrix

We investigate the magnetic fabrics and microstructures of diamagnetic rocksalt samples from the Sedom salt wall (diapir), Dead Sea Basin, as possible strain markers. A comprehensive study of anisotropy of magnetic susceptibility (AMS), combined with magnetic, microtextural, geochemical and mineralogical analyses allows us to depict the deformation mechanisms and to reveal the mineral sources of the AMS. The rocksalts are composed of halite as the major mineral phase (&gt;80%) and anhydrite as a minor phase (5–20%), and have an average magnetic susceptibility value of −13.4 ± 0.7 × 10−6 SI. Ferromagnetic and paramagnetic minerals make a negligible contribution to the bulk magnetic properties of the samples. The AMS indicates and reveals significant anisotropy with the maximum susceptibility axis (K1) subparallel to the bedding strike, although the cubic halite crystals are isotropic. Polarizing microscope and SEM images show preferred alignment of needle-like anhydrite crystals parallel to the direction of the K1 axis. Petrographic investigation of gamma irradiated thin sections reveals the deformation recorded in the microstructures of the rocksalts and points to a dominant contribution by dislocation creep, although both dislocation creep and pressure solution were active deformation mechanisms. We infer that during dislocation creep, the thin bands of anhydrite crystals deform along with the surrounding halite grains. We suggest that although the shape preferred orientation of halite grains is not indicative of finite strain because of resetting by grain boundary migration, the preferred orientation of the anhydrite crystals may be. These results suggest that the AMS of the rocksalts provides a textural proxy that reflects deformation processes of the rocksalts, despite their very low magnetic susceptibility.

Balloon expandable coronary stent materials: a systematic review focused on clinical success

Balloon expandable coronary stenting has revolutionized the field of interventional cardiology as a potential, minimally invasive modality for treating coronary artery disease. Even though stenting is successful compared to angioplasty (that leaves no stent in place), still there are many associated clinical complications. Bare metal stents are associated with in-stent restenosis caused mostly by neointimal hyperplasia, whereas success of drug-eluting stents comes at the expense of late-stent thrombosis and neoatherosclerosis. Even though innovative and promising, clinical trials with bioabsorbable stents reported thrombosis and a rapid pace of degradation without performing scaffolding action in several instances. It should be noted that a vast majority of these stents are based on a metallic platform which still holds the potential to mitigate major cardiovascular events and reduced economic burden to patients, alongside continuous improvement in stent technology and antiplatelet regimes. Hence, a systematic review was conducted following PRISMA guidelines to assess the clinically relevant material properties for a metallic stent material. From a materials perspective, the major causes identified for clinical failure of stents are inferior mechanical properties and blood-material interaction–related complications at the stent surface. In addition to these, the stent material should possess increased radiopacity for improved visibility and lower magnetic susceptibility values for artefact reduction. Moreover, the review provides an overview of future scope of percutaneous coronary interventional strategy. Most importantly, this review highlights the need for an interdisciplinary approach by clinicians, biomaterial scientists, and interventional cardiologists to collaborate in mitigating the impediments associated with cardiovascular stents for alleviating sufferings of millions of people worldwide.

Effective magnetic susceptibility of 3D-printed porous metal scaffolds.

3D-printed porous metal scaffolds are a promising emerging technology in orthopedic implant design. Compared to solid metal implants, porous metal implants have lower magnetic susceptibility values, which have a direct impact on imaging time and image quality. The purpose of this study is to determine the relationship between porosity and effective susceptibility through quantitative estimates informed by comparing coregistered scanned and simulated field maps. Five porous scaffold cylinders were designed and 3D-printed in titanium alloy (Ti-6Al-4V) with nominal porosities ranging from 60% to 90% using a cellular sheet-based gyroid design. The effective susceptibility of each cylinder was estimated by comparing acquired B0 field maps against simulations of a solid cylinder of varying assigned magnetic susceptibility, where the orientation and volume of interest of the simulations was informed by a custom alignment phantom. Magnitude images and field maps showed obvious decreases in artifact size and field inhomogeneity with increasing porosity. The effective susceptibility was found to be linearly correlated with porosity (R2 =0.9993). The extrapolated 100% porous (no metal) magnetic susceptibility was -9.9ppm, closely matching the expected value of pure water (-9ppm), indicating a reliable estimation of susceptibility. Effective susceptibility of porous metal scaffolds is linearly correlated with porosity. Highly porous implants have sufficiently low effective susceptibilities to be more amenable to routine imaging with MRI.

Magnetic susceptibility in the deep gray matter may be modulated by apolipoprotein E4 and age with regional predilections: a quantitative susceptibility mapping study.

To examine the relationship between apolipoprotein E gene (APOE) mutation status and iron accumulation in the deep gray matter of subjects with cognitive symptoms using quantitative susceptibility mapping (QSM). A total of 105 patients with cognitive symptoms were enrolled. QSM data were generated from 3D gradient-echo data using an STI Suite algorithm. A region of interest-based analysis with QSM was performed in the deep gray matter. Differences between APOE4 carriers and non-carriers were assessed by analysis of covariance. Multiple regression analysis was performed to identify the factors associated with magnetic susceptibility. Clinical characters such as age, education, MMSE, vascular risk burden, and systolic blood pressure differ between APOE4 carrier and non-carrier groups. The APOE4 carrier group had higher magnetic susceptibility values than the non-carrier group, with significant differences in the caudate (p = 0.004), putamen (p < 0.0001), and globus pallidus (p < 0.0001) which imply higher iron accumulation. In a multiple regression analysis, APOE4 status was found to be a predictor of magnetic susceptibility value in the globus pallidus (p = 0.03); age for magnetic susceptibility value in the caudate nucleus (p = 0.0064); and age and hippocampal atrophy for magnetic susceptibility value in the putamen (p < 0.05). Our study demonstrates that magnetic susceptibility in globus pallidus is related to APOE4 status while those of caudate and putamen are related to other factors including age. It suggests that brain iron accumulation in the deep gray matter is modulated by APOE4 and age with differential regional predilection.

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

INVESTIGATION OF SENSITIVE ELEMENTS OF TEMPERATURE TRANSDUCERS BASED ON THERMOMETRIC MATERIAL Lu1-xScxNiSb

Magnetic petrology of the Neoarchean granitoids in the Vila Jussara Suite, Carajás Province, Amazonian Craton

The Vila Jussara Suite (VJS) is formed by Neoarchean (~ 2.75 Ga) granites that are located in the Sapucaia Domain of the Carajás Province (CP), Amazonian Craton. Four petrographic varieties were identified in the VJS: biotite-hornblende monzogranite (BHMzG); biotite-hornblende tonalite (BHTnl); biotite monzogranite (BMzG); and hornblende-biotite granodiorite (HBGd). In terms of magnetic signature, BHMzG has two subgroups: the first subgroup has low magnetic susceptibility (MS) values (0.16 × 10-3 to 0.81 × 10-3) and more commonly contains ilmenite with titanite rims; the second subgroup shows moderate to high MS (1.91 × 10-3 to 6.02 × 10-3) and magnetite dominant over ilmenite. BHTnl has moderate MS (0.85 × 10-3 to 1.36 × 10-3) and dominance of pyrite followed by magnetite. BMzG and HBGd have comparatively high MS (3.35 × 10-3 to 19.3 × 10-3 and 2.14 × 10-3 to 25.0 × 10-3, respectively), with magnetite dominant over pyrite. The granite varieties of the VJS were formed under different oxygen fugacity (fO2) conditions, varying from reducing (< fayalite-magnetite-quartz (FMQ)) to oxidizing conditions (nickel-nickel oxide (NNO) to NNO+1). In addition, biotite-hornblende syenogranite occurs subordinately and shows high MS values and extremely high FeOt/(FeOt + MgO) ratios, both in whole-rock and amphibole and biotite. The granites of the VJS are similar to other Neoarchean granites of the Carajás province. The reduced VJS granites are akin to the ferroan granites of Planalto suite, Estrela Complex and Vila União area and the magnesian granites of VJS approach the magnesian granites of Vila União area.

STUDIES OF THERMOMETRIC MATERIAL Lu1-xZrxNiSb

The results of experimental research of perspective thermometric material Lu1-xZrxNiSbwhich can be used for the production of sensitive elements of thermoelectric and electroresistive thermometers are presented. Thermometric materials Lu1-xZrxNiSb, x=0.01–0.10, were made by fusing a charge of components in an electric arc furnace with a tungsten electrode (cathode) in an atmosphere of purified argon under a pressure of 0.1 kPa on a copper water-cooled hearth (anode). Heat treatment of alloys consisted of homogenizing annealing at a temperature of 1073 K. Annealing of samples was carried out for 720 h in vacuumed up to 1.0 Pa ampoules of quartz glass in muffle electric furnaces with temperature control with an accuracy of ±10 K. Diffraction arrays were obtained on a diffractometer DRON-4.0 (FeKα radiation), and the structural characteristics of Lu1-xZrxNiSbwere calculated using the Fullprof program. The chemical and phase compositions of the samples were monitored using a scanning electron microscope (Tescan Vega 3 LMU). The study of the temperature dependences of the resistivity ρ(T,x) and the thermopower coefficientα(T,x) Lu1-xZrxNiSb was performed in the temperature range of 80÷400 K on samples in the form of rectangular parallelepipeds measuring ~1.0×1.0×5.0 mm3 . Measurements of the values of the specific magnetic susceptibility χ(x) of Lu1-xZrxNiSb samples were performed by the relative Faraday method at a temperature of 273 K using a thermogravimetric installation with an electronic microbalance EM-5-ZMP in magnetic fields up to 10 kGs. Microprobe analysis of the concentration of atoms on the surface of Lu1-xZrxNiSb samples, x=0.01–0.10, established their correspondence to the initial compositions of the charge, and X-ray phase analysis showed no traces of extraneous phases on the sample diffractograms, except for the main phase. The nonmonotonic nature of the change in the values of the unit cell period of the thermometric material an (x) Lu1-xZrxNiSb, x=0.01–0.10, which differs from the results of modeling structural characteristics using software packages AkaiKKR and Elk. The nonmonotonic change in the values of the period of the unit cell a(x) Lu1-xZrxNiSband the presence of the extremum dependence suggests that the impurity Zr atoms introduced into the matrix of the LuNiSb basic semiconductor can simultaneously occupy partially different crystallographic positions in different ratios. The temperature resistivities ρ and the thermopower coefficientα of the LuNiSb base semiconductor contain high- and lowtemperature activation regions, which is characteristic of doped and compensated semiconductors. The introduction into the LuNiSb structure of the lowest concentration of impurity Zr atoms in the experiment (x=0.01) radically changes both the behavior of the temperature dependences of the resistivity ρ and the thermopower coefficientα and the type of the main electric current carriers. The values of the resistivity ρ(T,x) Lu1-xZrxNiSbonly increase with increasing temperature, which is characteristic of the metallic type of electrical conductivity and is due to the mechanisms of scattering of current carriers. This nature of the change in electrical resistance ρ(T,x) is evidence that the Fermi level εF has left the bandgap εg and is in the conduction band εC. This is indicated by the negative values of thermopower coefficientα(T,x) at all concentrations and temperatures. Studies of the magnetic susceptibility χ(x) showed that the samples as a basic semiconductor LuNiSb, as well as the thermometric material Lu1-xZrxNiSb, at all concentrations of impurities Zr, are Pauli paramagnetic. There is a synchronicity of the behavior of χ(x) with the dependences of the resistivity ρ(x, T) and the thermopower coefficient α(x, T), which is due to the change in the density of states at the Fermi level g(εF). The results of experimental studies of the Lu1-xZrxNiSbthermometric material completely coincide with the results of modeling its kinetic characteristics under the presence of vacancies in the crystallographic positions 4a and 4c of the Lu and Ni atoms, respectively. Such studies allow making adjustments in the structural studies of thermometric material with an accuracy that significantly exceeds the accuracy of X-ray research methods. The obtained results will allow us to clarify the spatial arrangement of atoms in the nodes of the unit cell, as well as to identify the mechanisms of electrical conductivity to determine the conditions for the synthesis of thermosensitive materials with maximum efficiency of thermal energy conversion into electricity.

Preliminary Investigation of Soil and Sediments Using Magnetic Susceptibility Method in Kogi State, Nigeria

Over the years, there has been significant increase in population and urbanization in Kogi State as a result of rural - urban migration. This has become a major threat to soil sustainability which is a natural non-renewable resource. The aim of this research is to carry out magnetic susceptibility mapping on the surface and subsurface soil of Kogi State using environmental magnetism techniques and geochemical analysis. The susceptibility test on rock samples and background soil samples within the study area shows an average of about 112.0 × 10^-5 SI. The magnetic susceptibility measurement on soil from Kogi State shows magnetic susceptibility enhancement of about (450.0 - 700.0) × 10^-5 SI. These values were dominant along the major towns, road pavements and commercial areas at the surface to a depth of about 50.0 cm in soil profiles. The 2D spatial distribution of magnetic susceptibility with depth reveals that these magnetic grains are distributed in the subsurface as a result of anthropogenic loading. The frequency-dependence of magnetic susceptibility (χfd%) values are very low (2 - 10.0 %) in most of the areas on the surface soil. These values indicate that the magnetic properties are predominantly contributed by the coarse multi-domain (MD) and stable single-domain (SSD) grains of anthropogenic origin. Atomic Absorbtion Spectrometer (AAS) analysis of these soil samples indicates the presence of Lead (300.0 - 900.0) mg/l and Cadmium (20.0 - 60.0) mg/l in large concentration at the surface soil in most part of the Kogi State. While Chromium show relatively low concentration on the surface soil. From the statistical correlation analysis, Lead and Cadmium show high positive correlation with magnetic susceptibility. These results suggests that the high enhancement of magnetic susceptibility on the surface and sub-surface soil in most part of Kogi State arise from anthropogenic activities rather than lithological and pedogenic processes and most likely cause by high concentration of Lead and Cadmium.

Changes in elements and magnetic properties of Sendai Bay sediments caused by the 2011 Tohoku‐oki tsunami

AbstractNearshore marine sediments deposited along island arcs can preserve evidence of past disaster events, such as tsunamis. Evidence of a tsunami that occurred off the Pacific coast of Tohoku, Japan, on March 11, 2011, was likely preserved in marine sediments. Using geochemical and rock magnetic analyses, this study aimed to investigate tsunami records preserved in marine sediments in Sendai Bay, located west of the epicenter of the 2011 Tohoku earthquake. We collected sediment samples at five stations (S‐1, S‐2, S‐3, S‐4, and S‐5) in Sendai Bay from 2002 to 2014. We compared the samples collected before and after the tsunami. We established that the silt component increased, while that of fine sand decreased at stations S‐3, S‐4, and S‐5 in the 2011 sediment sample. Notably, the concentrations of terrestrial and industrial metallic elements (Cu, Zn, and Pb) and total nitrogen, carbon, and sulfur amounts increased, while the magnetic susceptibility and isothermal remanent magnetization values decreased after the tsunami. We also found that Ti‐poor magnetite increased in the 2011 samples, indicating tsunami‐mediated changes. The study area experienced a large typhoon 6 months after the tsunami, leading to flooding. The elevation in the total organic carbon and total nitrogen ratio in the 2012 sample suggested that terrestrial organic matter was supplied by the flood.

Quantitative susceptibility mapping in assessment of inflammation and neurodegeneration in multiple sclerosis

Quantitative susceptibility mapping (QSM) is a relatively new MRI technique that may potentially help estimate iron concentrations in the brain. It plays a big role in diagnosis of many pathological processes, including multiple sclerosis (MS). Iron metabolism in the brain is a complex and not fully understood process. It is known that the content of iron in the brain increases with age; in addition, its accumulation is often observed in many neurodegenerative diseases, including MS foci, and its amount changes over time. In this regard, the values of magnetic susceptibility obtained using QSM can potentially become a convenient biomarker that reflects the latent activity and progression of MS, which, in turn, can influence the choice of therapy and the tactics of treating patients.

Synthesis, characterization and biological activities study of metal complexes of 5,6-dimethylbenzimidazole with Co(II), Cu(II), Cd(II) and Hg(II)

The present work aimed at the synthesis of cobalt(Ⅱ), copper(Ⅱ), cadmium(Ⅱ) and mercury(Ⅱ) complexes of 5,6-dimethylbenzimidazole by simple and straight forward methods. Several elemental, spectroscopic and thermal studies such as; solubility, melting point, elemental analysis, FTIR spectroscopy, UV–visible spectroscopy, magnetic susceptibility, conductivity test, TGA, DSC and XRD were carried out to characterize the synthesized complexes. Elemental analysis (C, H, N, M) data confirmed 1:2 metal to ligand ratio represented as [M(L)2Cl2]. UV–visible spectra and Magnetic susceptibility values suggested tetrahedral geometry of the synthesized metal complexes. The lattice types were predicted by XRD data and conductivity values indicated non-electrolytic nature of the complexes. TGA and DSC data demonstrated their thermal decomposition patterns as well as formation of corresponding metal oxides. Combining all the analytical results, the proposed empirical formulae of the complexes are [Co(C9H10N2)2Cl2], [Cu(C9H10N2)2Cl2], [Cd(C9H10N2)2Cl2] and [Hg(C9H10N2)2Cl2]. The synthesized complexes were also subjected to antimicrobial and cytotoxicity activity screening. Cd(II) and Hg(II) complexes showed activity against both gram positive and negative bacterial strains at relatively higher concentration. Most of the complexes were less or insensitive to bacterial and fungal strains at lower concentration. All of the synthesized complexes exhibited potential cytotoxic activity.

Расчет кривой Столетова конструкционных сталей по параметрам предельной петли магнитного гистерезиса

A formula has been developed for calculating the steel Stoletov curve (a graphic dependence of magnetic susceptibility χ on the magnetic field strength H in a ferromagnet) based on the results of measuring the coercive force Hc, technical saturation magnetization Ms and residual magnetization Mr. The derived formula is substantiated by a statistical analysis of a comparison between the calculation and experimental results obtained for grade SHX15 steel in its delivery and hardened states. The correlation coefficient between the calculated and measured values of χ in the entire variation range of H was 0.99, and the mean square deviation was 8.7%. By using the developed formula, it is possible to construct the dependence χ(H) and analyze it in different magnetic field strength variation ranges for any steel the measured values of Hc, Ms and Mr for which are given in the reference literature. The application of the formula is illustrated by analyzing the effect the tempering temperature of grade 30 steel after its quenching has on the steel Stoletov curves. The grade 30 steel tempering temperature has been established at which the required magnetic susceptibility value can be obtained in a given magnetic field strength variation range in a ferromagnet with its required hardness.

Motor cortical patterns of upper motor neuron pathology in amyotrophic lateral sclerosis: A 3 T MRI study with iron-sensitive sequences

BackgroundPatterns of initiation and propagation of disease in Amyotrophic Lateral Sclerosis (ALS) are still partly unknown. Single or multiple foci of neurodegeneration followed by disease diffusion to contiguous or connected regions have been proposed as mechanisms underlying symptom occurrence. Here, we investigated cortical patterns of upper motor neuron (UMN) pathology in ALS using iron-sensitive MR imaging. MethodsSignal intensity and magnetic susceptibility of the primary motor cortex (M1), which are associated with clinical UMN burden and neuroinflammation, were assessed in 78 ALS patients using respectively T2*-weighted images and Quantitative Susceptibility Maps. The signal intensity of the whole M1 and each of its functional regions was rated as normal or reduced, and the magnetic susceptibility of each M1 region was measured. ResultsThe highest frequencies of T2* hypointensity were found in M1 regions associated with the body sites of symptom onset. Homologous M1 regions were both hypointense in 80–93 % of patients with cortical abnormalities, and magnetic susceptibility values measured in homologous M1 regions were strongly correlated with each other (ρ = 0.88; p < 0.0001). In some cases, the T2* hypointensity was detectable in two non-contiguous M1 regions but spared the cortex in between. ConclusionsM1 regions associated with the body site of onset are frequently affected at imaging. The simultaneous involvement of both homologous M1 regions is frequent, followed by that of adjacent regions; the affection of non-contiguous regions, instead, seems rare. This type of cortical involvement suggests the interhemispheric connections as one of the preferential paths for the UMN pathology diffusion in ALS.

Validation of the use of portable equipment for magnetic characterization of soils, State of Paraná, Brazil

Studies involving the magnetic susceptibility (MS) of rocks are becoming increasingly frequent in geological surveys, mainly in those with petrogenetic approaches and in mineral prospecting. Portable devices have become a good alternative for data acquisition because of their practicality and low cost when compared to laboratory analyses. To assess the efficiency of data acquisition with such devices, 291 soil samples were measured with a Terra Plus KT-5 portable device in the field and with a double frequency Bartington MS2B sensor, with mass correction, in the laboratory. The data obtained allowed the characterization of four distinct populations, ranging from high to very low MS values. Statistical analysis showed good correlation between measurements with mass correction in the laboratory and those made with portable devices, resulting in a correlation coefficient (r) = 0.98. All samples obtained in the field and laboratory were utilized in this correlation. The populations identified by both means are in agreement, with subtle discrepancies, thereby demonstrating the efficiency of portable equipment for acquisition of MS data in geological studies.

Different characteristics of barren and W–Mo–productive Cretaceous granites in the Hwanggangri mineralized district, South Korea

The Hwanggangri mineralized district (HMD) in South Korea contains a variety of ore deposits such as porphyry or skarn (Mo, Cu–Pb–Zn), carbonate replacement, and fissure–filling vein types (W–Mo, Au–Ag, fluorite). The HMD is located on the boundary of the Okcheon metamorphic belt and the Taebaeksan Basin. Most of the deposits are hosted in limestones/dolomitic limestones of the Joseon Supergroup, and the age of mineralization is Late Cretaceous (96.5–76.2 Ma) including Geumseong, Jungbo, Kwangsin, and Geumsil deposits. These granites are mainly magnetite-series biotite granites, and they can be categorized into early- and late-stage on the basis of mineral assemblage, texture, grain size, and magnetic susceptibility. Magnetite is present in some of the granites, and some of the early-stage granites retain the high magnetic susceptibility values typical of the magnetite series. However, the late-stage granites show a wide range of magnetic susceptibility values, including low ones due to fractionation. The emplacement ages of the Sokrisan, Weolaksan, Muamsa, and Susan granite bodies are 94–88 Ma, similar to the ages of mineralization in the study area. The Cretaceous granites reported to be related to W–Mo mineralization in the HMD show miarolitic, porphyritic, and micrographic textures indicating considerable hydrothermal fluid activity in a shallow environment. The rocks of the Sokrisan granite are mostly early stage, those of the Weolaksan and Muamsa granites include both early and late stages, and the studied samples of the Susan granite are entirely late stage. These four Cretaceous granites have more than 70 wt% SiO2, high Rb/Sr ratios, depletions in compatible elements, enrichments in incompatible elements, and tetrad patterns with depleted LREEs, enriched HREEs, and strong negative Eu anomalies. They all belong to the high–K calc–alkaline series, are dominantly peraluminous, and can be classified as strongly fractionated I–type granites. The Sokrisan, Weolaksan, Muamsa, and Susan granites have similar emplacement ages and geochemical characteristics that indicate the same magma source. However, the Sokrisan granite, with its mainly early-stage rocks, consistently higher magnetic susceptibility values, and relatively high Nb/Ta values, differs from the other Cretaceous granites in the HMD. This suggests that the widely exposed Sokrisan granite of batholith type has been eroded substantially, removing the late-stage rocks and ore deposits. In contrast, the stock–type Susan granite has undergone relatively little erosion, and it represents well the late-stage parts of the Cretaceous granites in the HMD. The Cretaceous granites in the HMD have mostly highly-fractionated geochemical characteristics, and the late-stage rocks that are more associated with W–Mo mineralization are more fractionated than the early-stage rocks. The respective productivities of the Susan, Muamsa, Weolaksan, and Sokrisan granites range from high to low, and the more-productive late-stage granites are still present, as they have undergone less erosion.

Quantitative evaluation of brain iron accumulation in different stages of Parkinson's disease.

Excessive brain iron deposition is involved in Parkinson's disease (PD) pathogenesis. However, the correlation of iron accumulation in various brain nuclei is not well-established in different stages of the disease. This cross-sectional study aims to evaluate quantitative susceptibility mapping (QSM) as an imaging technique to measure brain iron accumulation in PD patients in different stages compared to healthy controls. Ninety-six PD patients grouped by their Hoehn and Yahr (H&Y) stages and 31 healthy controls were included in this analysis. The magnetic susceptibility values of the substantia nigra (SN), red nucleus (RN), caudate, putamen, and globus pallidus were obtained and compared. Iron level was increased in the SN of PD patients in all stages versus controls (p<.001), with no significant difference within stages. Iron in the RN was significantly increased in stage II versus controls (p=.013) and combined stages III and IV versus controls (p<.001). The iron levels in caudate, putamen, and globus pallidus were not different between any groups. Our data suggest iron accumulation occurs early in the disease course and only in the SN and RN of these patients. This is a large cross-sectional study of brain iron deposition in PD patients according to H&Y staging. Prospective studies are warranted to further validate QSM as a method to follow brain iron, which could serve as a disease biomarker and a therapeutic target.