High Magnetic Susceptibility Research Articles

Local atomic structure of amorphous Fe81−xCoxNb7B12 alloys using synchrotron radiation x-ray diffraction and pair-distribution function analysis

Fe81−xCoxNb7B12 alloys are members of the high thermal stability and magnetic performance (HITPERM) family of materials, which exhibit exceptional magnetic properties, including high Curie temperatures and magnetic susceptibilities, making them promising for developing materials platforms for high-frequency, high-temperature applications. Here, we combine synchrotron x-ray diffraction measurements with simulations of the pair-distribution function to uncover the local atomic structure of amorphous Fe81−xCoxNb7B12 alloys. By analyzing alloys with varying Fe:Co ratios, we demonstrate how the composition impacts the atomic structure of these alloys. Our study reveals that Fe and Co form clusters near the equiatomic Fe/Co concentration.

Magnetic forward modelling for high susceptibility at arbitrary heights based on compressed 2D and 3D fast discrete #xD;convolution techniques

Fast 3D magnetic forward modeling for the high susceptibility is a considerable challenge that hinders the 3D efficient inversion imaging and high-precision magnetic exploration of large-scale magnetic data. An efficient compressed 2D and 3D discrete convolution fast Fourier transform techniques is employed to compute the magnetic anomaly caused by 3D bodies of arbitrary shapes and high magnetic susceptibility at arbitrary height. The compressed kernel matrix technique is applied to minimize the computation and storage of the kernel matrix when the model is uniformly discretized, dramatically reducing the memory requirements and processing time without any loss of accuracy. Meanwhile, the compressed kernel matrix makes it possible to use a 3D discrete convolution fast Fourier transform technique to achieve fast matrix-vector multiplication, further improving the efficiency of the discrete convolution. Additionally, a contraction operator technique is introduced to adjust the effective magnetization for accelerating and guaranteeing the convergence of the iterative procedure. Then, the compressed 2D discrete convolution fast Fourier transform technique is implemented to realize the fast convolution of the compressed kernel matrix and the effective magnetization, and finally obtain the magnetic field at arbitrary height. The sphere and spherical shell models which have analytical solutions are used to validate the accuracy of the proposed method. Next, we investigated the impact of magnetic susceptibility and model mesh size on convergence behavior of the proposed method. Then, we evaluate the computing performance of the proposed method by comparing it to the enhanced space-domain convolution-based approach for different observation heights and rectangular prismatic mesh sizes. The results indicate that the advantages of the proposed method improve more and more notable as the number of grids and observation height increase. Finally, we examine the influence of the mutual magnetization with different magnetic susceptibility.

Active Fabric Origami Enabled by Digital Embroidery of Magnetic Yarns.

Active fabrics can perform deformations such as contraction, expansion, and bending when exposed to external stimuli. Origami, the ancient art of paper folding, transforms a 2D sheet into a complex 3D structure. However, integrating origami-inspired designs into active fabrics presents significant challenges, including the large-scale production of stimuli-responsive yarns that can be processed using standard textile techniques to achieve intricate origami patterns with high precision and versatility. In this work, the large-scale fabrication of magnetic yarns featuring high magnetic susceptibility, mechanical strength, and flexibility is reported, which is enabled by processing magnetic polymer composites with a series of textile engineering processes. Utilizing digital embroidery, these magnetic yarns are programmed into origami patterns with predefined yarn alignments on flexible fabrics to create various active fabric origami structures that are mechanical durable and functional consistent. These structures can reversibly transform among shapes in response to specific magnetic fields, enabling a range of functionalities such as altering surface roughness, delivering linear actuation, mimicking flower blooming, and providing switchable thermal insulation. The novel active fabric origami provides promising smart platforms across areas as diverse as smart textiles, soft robotics, wearable devices, and fashion.

Geological and ground magnetic studies on the Ochre-Um Greifat hydrothermal deposits and their relationship to geological structures, Central Eastern Desert, Egypt

The current study offers an integrated approach for investigating the Ochre-Um Greifat hydrothermal deposits in the Central Eastern Desert of Egypt and its applicability to other regions with similar geology, conditions, and circumstances around the world. This work is characterized by combining detailed geological studies with ground magnetic data processing techniques to delineate hydrothermal zones associated with this specific deposit. This integrated approach presents a more robust and effective framework for deciphering potential mineralized zones, offering an outstanding advancement for exploration of Ochre-Um Greifat hydrothermal deposits and similar types. The outcropped rock units and structures in the study area were mapped through geological field investigations. The results revealed that the NNW-SSE normal fault and its branches, the WNW-ESE sinistral strike-slip fault, and its Riedel shears influence the area. The findings of chemical analyses indicate that Miocene clastic carbonate sedimentary rocks have anomalous lead (Pb) and copper (Cu) concentrations, as well as high iron (Fe) and zinc (Zn). These findings also include uranium (U), whose grades range from low to high. Ground magnetic data was applied to determine basement depth, geologic structures, and their relationship to mineralization deposits. The high magnetic anomalies in the study area could have contributed to the formation of ochre deposits. Ground magnetic data were inverted to 3-D models to construct a reliable geological model of the studied area. The resulting models highlighted the locations of significant high magnetic susceptibility zones (may be a magmatic source rich in iron) responsible for Ochre-Um Greifat hydrothermal deposits, as well as their lateral and vertical extensions. These zones are considered potential exploration areas.

Origin and composition of hydrothermally‐influenced sediments at Aurora Vent Field, southwestern Gakkel Ridge (82.9°N)

ABSTRACTSlow–ultraslow spreading ridges represent half of the total length of the global mid‐ocean ridge system and have been recognized to host hydrothermal activity. Their role as a source versus sink of elements in the oceans remains poorly constrained. Here, we present the first sediment data from the Aurora Vent Field (~3900 m depth) on the ultraslow spreading Gakkel mid‐ocean ridge and the northernmost active vent field (82.9°N) explored to date. We interpret the composition of the cores at various distances from the vents based on physical parameters (P‐wave velocity, gamma density, magnetic susceptibility, acoustic impedance and fractional porosity), mineralogy and (in)organic geochemistry (elemental analysis via X‐Ray fluorescence and carbon–nitrogen systematics). Metalliferous sediments in two blade cores at <10 m from a black smoker are dominated by Fe‐hydroxides (goethite) and Cu‐Fe‐bearing sulphide minerals (mainly chalcopyrite) that are rich in Co and Zn. These sediments form a friable crust associated with yellow microbial mats visible on the seafloor with the remotely operated vehicle imagery. Near‐field plume deposits form an ~50 cm thick unit at the top of gravity cores close to the vents (<500 m). This unit transitions at further distance into laminated plume fallout deposits marked by high magnetic susceptibility and elevated ln(Fe/Ti), ln(Cu/Ti) and ln(Zn/Ti) values in the XRF profiles. Sedimentary organic matter in the investigated cores is dominated by a marine source, which is overprinted by microbial mats in the surface sediments of the blade cores. In one blade core, we found evidence of thermal alteration of the organic matter, typified by elevated C/N ratios and heavier δ13CTOC. Radiocarbon dating of foraminifera in a gravity core yielded an age of 27 230 cal bp, evidence for protracted vent activity preceding the Last Glacial Maximum 23 to 19 ka. Finally, we propose a sedimentological model for the Aurora hydrothermally influenced system that can be potentially exported to analogues worldwide.

Rock Magnetic Evidence for the Seismogenic Environment of Large Earthquakes in the Motuo Fault Zone, Eastern Himalayan Syntaxis

Abstract Knowledge of the seismogenic environment of fault zones is critical for understanding the processes and mechanisms of large earthquakes. We conducted a rock magnetic study of the fault rocks and protoliths to investigate the seismogenic environment of earthquakes in the Motuo fault zone, in the eastern Himalayan syntaxis. The results indicate that magnetite is the principal magnetic carrier in the fault rocks and protolith, while the protolith has a higher content of paramagnetic minerals than the fault rocks. The fault rocks are characterized by a high magnetic susceptibility relative to the protolith in the Motuo fault zone. This is likely due to the thermal alteration of paramagnetic minerals to magnetite caused by coseismic frictional heating with concomitant hydrothermal fluid circulation. The high magnetic susceptibility of the fault rocks and neoformed magnetite indicate that large earthquakes with frictional heating temperatures >500°C have occurred in the Motuo fault zone in the past, and that the fault maintained an oxidizing environment with weak fluid action during these earthquakes. Our results reveal the seismogenic environment of the Motuo fault zone, and they are potentially important for the evaluation of the regional stability in the eastern Himalayan syntaxis.

New Insight into Geochemistry and Mineralogy of Deep Caves in Croatian Karst and Its Implications for Environmental Impacts

This study examines speleothems, sediments, rock, and water to assess geochemical and mineralogical processes in deep karst systems. Focusing on Slovačka jama cave (−1320 m deep) and the Velebita cave system (−1026 m deep), we identify elemental and mineralogical anomalies that provide valuable records of element transport, mineral formation, and paleoenvironmental changes. Heavy metal anomalies (Al, B, Co, Mn, Na, Tl, Ba, Be, Cr, Cu, Fe, K, Pb, Rb, Ti, U, Zn) at 300–400 m of depth in Slovačka jama indicate a complex interplay of geological conditions, geomorphological processes, atmospheric deposition, and potential anthropogenic influences. Factor analysis reveals two elemental associations: (1) Fe, Pb, Cu, and Zn, linked to terrigenous aluminosilicates, and (2) Cd, Cr, Mo, and Ni, suggesting airborne or geological sources. Mineralogical analysis confirms the dominance of calcite, with quartz, clay minerals, feldspars, magnetite, and goethite also detected. High magnetic susceptibility values in sediment-rich samples suggest Fe-rich mineral inputs from weathering, biogenic activity, or industrial sources. Ba anomalies in feldspar-rich samples and Sr accumulation at depth indicate distinct geochemical processes. These findings enhance our understanding of deep karst geochemistry, crucial for paleoenvironmental reconstructions and groundwater protection.

Pervasive Millennial-Scale Interstadial/Interglacial Climate Variability in the High-Latitude Northern Hemisphere

IODP Ex. 323 to the Bering Sea recovered a detailed record of Quaternary environmental variability adjacent to Alaska and eastern Siberia. The deep-sea sediment records show a dramatic bimodal environmental record of alternating high versus low magnetic susceptibility. Oxygen isotope records indicate that the interglacials are times of high clastic flux (high magnetic susceptibility) from the adjacent continents into the Bering Sea. Subsequent, more detailed chronostratigraphy indicates that Interstadial 3 and Interglacials 5, 7, and 9 are also intervals of large-amplitude, millennial-scale environmental variability alternating between warmer/wetter and cooler/drier intervals, with a quasi-cyclicity of ~5000 years. Comparative studies of North Atlantic Quaternary sediments associated with ODP Leg 172, with a similar dramatic glacial/interglacial variation in carbonate, show an almost identical millennial-scale (~5000 yrs) pattern of variability that we attribute to alternating warmer/cooler intervals in Interstadial 3 and Interglacials 5, 7, and 9. These results can also be compared to findings for Lake Elgygytgyn in Siberia. The chronology of this record is less certain than those of the other two regions, but it, too, shows large-amplitude changes in magnetic susceptibility in Interstadial 3 and Interglacials 5, 7, and 9 that can be attributed to oscillating warmer/cooler conditions on a millennial scale. These results suggest a coherent, hemispheric-scale pattern of climate variability in interstadial/interglacial periods of the last 400 ka with a quasi-cyclicity of ~5000 years. We speculate that this cyclicity is driven by a harmonic of the chaotic precession Milankovich cyclicity.

Investigation of the relation between heavy metal and magnetic susceptibility of sediment from Kerala coast for contamination study with statistical approach

ABSTRACT Sediment samples collected from the Kerala Coast of India were analysed using a dual frequency susceptibility meter to determine magnetic susceptibility. The heavy metal concentration of the sediments, particularly V, Cr, Mn, Fe, Cu, Zn, Ba, Zr, As, Sr, and Pb, is determined using the EDXRF technique. The magnetic susceptibility measurement was conducted at two different frequencies: a low frequency of 0.47 kHz and a high frequency of 4.7 kHz. These measurements were then used to calculate the frequency-dependent susceptibility, also referred to as χ fd The low frequency mass magnetic susceptibility values range from 7 × 10−8 m3 kg−1 to 205 × 10−8 m3 kg−1, with an average of 85.59 × 10−8 m3 kg−1. The high magnetic susceptibility values range from 5 × 10−8 m3 kg−1 to 182 × 10−8 m3 kg−1, with an average of 74.27 × 10−8 m3 kg−1. A multivariate statistical analysis was performed to investigate the correlation between magnetic susceptibility and the concentration of heavy metals in sediments. A significant association established between magnetic susceptibility and the heavy metals such as V, Zn, Mn, Ba, As, and Pb. This suggests that these elements are affected by anthropogenic magnetic particulate matter and this type of contamination is of anthropogenic origin. A spatial distribution map a distinct visual representation of the magnetic susceptibility in the study area. The principal component analysis (PCA) results indicated a significant relationship between heavy metals and magnetic susceptibility values. The cluster analysis identified two distinctive groups, suggesting a relationship between the levels of heavy metals and magnetic susceptibility values. The analysis of the Pearson correlation coefficient revealed an association between magnetic susceptibility and the concentration of the studied heavy metal. The current investigation demonstrates that magnetic susceptibility is a rapid, cost-effective, and non-destructive technique for identifying contaminated sediments.

МАГНІТНІ ДОСЛІДЖЕННЯ ДОННИХ ВІДКЛАДІВ ТА ҐРУНТІВ ЯК ІНСТРУМЕНТ ВИЯВЛЕННЯ НЕБЕЗПЕЧНИХ ГЕОДИНАМІЧНИХ ЕКЗОГЕННИХ ПРОЦЕСІВ НА ПРИКЛАДІ ЗАПОВІДНИКА ХОРТИЦЯ

Background. During the military activity, areas with different types of land use experience significant negative impacts. The natural and anthropogenic complexes of the Khortytsia Nature Reserve are under constant threat from missile strikes, drone attacks, guided aerial bombs, and other forms of military activity. Additional pressure is exerted by the urban environment and heavy industry of Zaporizhzhia. Moreover, the disappearance of the Kakhovka Reservoir has led to irreversible changes in biodiversity, water regimes, and landscape conditions in the surrounding areas, including Khortytsia Island. The aim of this study is to assess the changes in the natural and anthropogenic complexes of the Khortytsia Reserve by analyzing magnetic properties and determining the concentrations of hazardous chemical compounds, particularly heavy metals, in the bottom sediments of dried-up lakes formed after the destruction of the Kakhovka Dam, as well as in the soil. Methods. Magnetic susceptibility was measured using a laboratory KLY-2 Kappabridge. Mass-specific magnetic susceptibility (χ) was determined by normalization to mass. The content of chemical elements was analyzed by X-ray fluorescence (XRF) analysis using Elvatech equipment. Results. The study considers the bottom sediments of Lake Kamyane, Prohniy, Rysove, and Pishchane, as well as the soil of the forested area. High magnetic susceptibility was detected. Most observation points recorded relatively high values of χ=50–100×10-8 m³/kg, while some samples exhibited even more extreme values (χ=100–300×10-8 m³/kg). These elevated values may be associated with either anthropogenic pollution or the lithogenic origin of magnetic minerals transported from crystalline basement outcrops in the vicinity of Khortytsia. Additionally, increased magnetic susceptibility was observed in the sandy soils of the mixed forest. A significant correlation with magnetic susceptibility was found only for chromium (correlation coefficient is 0.4). At the same time, exceedances of the maximum allowable concentrations of heavy metals were recorded: lead by 2–8 times, zinc by 2–10 times, chromium by 20–50 times, copper by 10–20 times, nickel by 5–20 times, and cobalt by 5–8 times. Conclusions. The magnetic susceptibility of the bottom sediments of lakes and the soil of Khortytsia Island is high. It is assumed that this is due to the accumulation of lithogenic material from the weathering of crystalline basement rocks. The concentration of a number of elements, primarily heavy metals, exceeds the MPC by 2–50 times. However, a significant correlation coefficient was recorded only between χ and Cr (0.4). Therefore, magnetic minerals do not have a genetic connection with materials containing heavy metals. That is, most likely there is no anthropogenic impact.

ИЗМЕНЕНИЕ ПЕТРОМАГНИТНЫХ ХАРАКТЕРИСТИК В ПОЗДНЕПЛЕЙСТОЦЕНОВЫХ-ГОЛОЦЕНОВЫХ ОСАДКАХ ЛЕДНИКОВОГО ОЗЕРА ГРЯЗЕВОЕ, ВЕРХНЯЯ КОЛЫМА

Lake Gryazevoe formed in the Late Pleistocene about 25 ka cal BP. Magnetic properties of sediments as thick as 780 cm reflect their accumulation conditions controlled primarily by climate. In the Late Pleistocene, terrigenous sediments were dominant in the basin. The composition of magnetic minerals and magnetic properties are similar in slope and lake sediments. Magnetic minerals are mainly titanomagnetites. Late Pleistocene sediments are characterized by relatively high values of magnetic susceptibility (MS), saturation magnetization (Js), and remanent saturation magnetization (Jrs). A noticeable change in sedimentation conditions associated with climatic changes occurred at the Pleistocene-Holocene boundary from 12.7 to 11.3 ka cal BP, which resulted in an increase of bioproductivity in the lake. Due to the dilution of detrital material by organic matter and biogenic silica, Holocene sediments have low MS, Js, and Jrs values. In the Early Holocene, chemogenic accumulation of highly coercive iron-containing minerals, presumably lepidocrocite, dominated. Holocene sediments are characterized by the formation of autigenic framboidal pyrite. Magnetic iron sulfides of greigite-pyrrhotite composition are observed in Pleistocene-Holocene transition layers. Cold climatic conditions are established in the Middle Holocene in the range of 4.7–6.9 ka cal BP. Sediments in this interval are characterized by higher MS, Js, and Jrs values, while the paramagnetic component decreases. The Late Pleistocene deposits contain a record of the geomagnetic field secular variations.

Process of Synthesis and Analysis of Nanoparticles Recovered by Magnetic Methods

Magnetic materials, particularly ferrites, are integral to various electronic and biomedical applications due to their unique magnetic and electrical properties. Ferrites, which typically adopt spinel structures, are synthesized by mixing iron oxide (Fe<sub>2</sub>O<sub>3</sub>) with other metallic elements, such as nickel, zinc, or manganese. They exhibit ferromagnetic behavior below the Curie temperature and paramagnetic properties above it. Iron oxide nanoparticles (NPs), particularly Fe<sub>3</sub>O<sub>4</sub> and γ-Fe<sub>2</sub>O<sub>3</sub>, have gained significant attention for their versatility in fields like catalysis, data storage, and biomedical technologies. Their superparamagnetism, high magnetic susceptibility, and biocompatibility make them particularly promising for targeted drug delivery, magnetic resonance imaging, and bioseparation. This review explores the various synthesis methods for iron oxide nanoparticles, including co-precipitation, thermal decomposition, hydrothermal synthesis, microemulsion, and sonochemical techniques. Each method has specific advantages and limitations, such as particle size control, monodispersity, and stability. The review also highlights the critical role of nanoscale characterization techniques, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), in understanding the structural, morphological, and compositional attributes of synthesized nanoparticles. These tools enable the optimization of synthesis parameters and the tailoring of nanoparticles for specific applications. Overall, advancements in synthesis and characterization are paving the way for innovative applications of iron oxide nanoparticles in catalysis, biomedical science, and beyond.

Dental Implant Artifacts in MRI: Compatibility and Considerations

This review investigated dental implant artifacts in magnetic resonance imaging (MRI) and their safety in clinical practice. Dental prostheses, including implants, crowns, and orthodontic appliances, cause artifacts due to their high magnetic susceptibility, particularly in materials like iron, stainless steel, and cobalt-chromium. Titanium implants are considered safe under MRI environments according to the American Society for Testing and Material (ASTM) standards, with no reported thermal injury or dislodgement during examinations. Despite limited artifacts from titanium's paramagnetic nature, minute ferromagnetic components can still affect visualization. Thus, reducing artifacts in oral and maxillofacial MRI scans is crucial. Two main categories of artifact reduction techniques are identified: improved porous titanium or alternative materials like zirconia and adjusting MR parameters with advanced sequences. Recommendations include increasing the readout bandwidth, reducing slice thickness, using spin-echo sequences instead of gradient-echo, and employing short tau inversion recovery or DIXON techniques for fat suppression. Additional methods like VAT, VAT-SEMAC combination, and MAVRIC show promise, although applicability may be restricted in specific MRI scanners. Continuous advancements in dental implant materials and MRI sequences are needed to improve imaging quality and reduce artifacts. Collaboration among dental practitioners, radiologists, and MRI technologists is essential for refining techniques and ensuring patient safety. Although overall dental implant artifacts pose challenges, safety in MRI is well-established. Ongoing developments hold significant potential to enhance MRI imaging quality in patients with dental devices

Iterative algorithm for computing magnetic field considering remanent magnetization and demagnetization

SUMMARY Efficient and high-precision methods for performing large-scale numerical calculations under high magnetic susceptibility conditions are essential for magnetic exploration applications. This paper proposes an algorithm for magnetic field modelling considering both demagnetization and remanent magnetization. The 3-D partial differential equation of magnetic potential is reduced to a 1-D ordinary differential equation in the space-wavenumber domain through a 2-D Fourier transform in the horizontal direction. Using the quadratic interpolation finite element method to obtain the pentagonal equation, the chasing method is used to solve the equation efficiently, and a contraction operator based on electromagnetic integral equation method is introduced to ensure stable iteration convergence. The validity of the algorithm was confirmed by comparing it with analytical solutions. Numerical examples demonstrate the importance of considering demagnetization under high magnetization conditions. Test results reveal that magnetic susceptibility is the sole factor affecting convergence among the factors examined. Further analysis showed that, for the same magnetic susceptibility, the algorithm converges with the same number of iterations and higher precision is achieved with an increasing number of nodes. Under the same grid configuration, higher magnetic susceptibility requires more iterations to converge and results in lower algorithm precision. The algorithm presented in this paper shows higher efficiency compared to those based on integral equations. Moreover, we demonstrate the algorithm's high accuracy when applied to models with anomalies near boundaries. Finally, the adaptability of the algorithm to complex geological models and undulating topography is verified by combining model tests with DEM data. This algorithm presents an efficient and high-precision method for magnetic field calculations under conditions of high susceptibility and strong remanent magnetization, offering promising prospects for geoscience applications.

Baseline magnetic susceptibility measurements of rocks in the Precambrian basement terrain of southwestern Nigeria

Petrological, mineralogical and magnetic susceptibility measurements have been studied within the southwestern Nigeria Precambrian basement rocks. Detail geological mapping and core sampling was done for mineralogical characterisation and magnetic susceptibility of the rock samples. Results of the petrographic analyses revealed: quartz, feldspars, hornblende, biotite and opaque (magnetite, ilmenite, maghemite, titanomaghemite) minerals; with minor component of ferromagnesian minerals like hornblende. Quartz, Microcline and Plagioclase alone constitute up to volume fractions 70 % of the rock in the thin section with plagioclase being the most dominant. The magnetic measurements have revealed that the volume susceptibilities K from the investigated samples range from 0.2 to 56,419 X10-6 [SI]. Charrnockites, Granite, biotite granite gneiss, banded gneiss, gneiss, aplite dike, granite, diorite granite gneiss ranges from: 10,059-56,419; 247-12856;0.2-129; 20.4-39.4; 14.1-22,366; 20-8250; 14-30233;4467-6641; and 632-26,921 X 10-6 [SI] respectively. Differential results in the frequency distribution is due varied composition of the paramagnetic (low magnetic susceptibility) and ferromagnetic (high magnetic susceptibility) grains in the rock specimen.

Magnetometric and seismic investigation of the Nova Colinas impact structure, Parnaíba Basin, Brazil

Magnetometric and seismic investigation of the Nova Colinas impact structure, Parnaíba Basin, Brazil

Imaging and modelling the subsurface structure of the Rungwe Volcanic Province in SW Tanzania with aeromagnetic data: An improved structural map to support geothermal exploration

Imaging and modelling the subsurface structure of the Rungwe Volcanic Province in SW Tanzania with aeromagnetic data: An improved structural map to support geothermal exploration

Effect of metallic materials on magnetic resonance image uniformity: a quantitative experimental study

ObjectiveTo assess quantitatively the effect of metallic materials on MR image uniformity using a standardized method.MethodsSix types of 1 cm cubic metallic materials (i.e., Au, Ag, Al, Au–Ag–Pd alloy, Ti, and Co–Cr alloy) embedded in a glass phantom filled were examined and compared with no metal condition inserted as a reference. The phantom was scanned five times under each condition using a 1.5-T MR superconducting magnet scanner with an 8-channel phased-array brain coil and head and neck coil. For each examination, the phantom was scanned in three planes: axial, coronal, and sagittal using T1-weighted spin echo (SE) and gradient echo (GRE) sequences in accordance with the American Society for Testing and Materials (ASTM) F2119-07 standard. Image uniformity was assessed using the non-uniformity index (NUI), which was developed by the National Electrical Manufacturers Association (NEMA), as an appropriate standardized measure for investigating magnetic field uniformity.ResultsT1-GRE images with Co–Cr typically elicited the lowest uniformity, followed by T1-GRE images with Ti, while all other metallic materials did not affect image uniformity. In particular, T1-GRE images with Co–Cr showed significantly higher NUI values as far as 6.6 cm at maximum equivalent to 11 slices centering around it in comparison with the measurement uncertainty from images without metallic materials.ConclusionWe found that MR image uniformity was influenced by the scanning sequence and coil type when Co–Cr and Ti were present. It is assumed that the image non-uniformity in Co–Cr and Ti is caused by their high magnetic susceptibility.

Aeromagnetic data reveals buried Quaternary drainage patterns in the Gulf of St Lawrence (Canada)

Short-wavelength, low-amplitude magnetic anomalies form dendritic patterns on the shallow water (<100 m depth) Magdalen Plateau in the Gulf of St Lawrence, Canada. High-resolution seismic data indicate that these magnetic anomalies are associated with 0.6–2 km wide incised Quaternary valleys with relatively flat bottoms lying 30–70 m below the seafloor. The magnetic signature of the valleys is due to high magnetic susceptibility volcanic detritus derived from the erosion of the volcanic rocks that overlie most of the salt bodies in this area. This study shows that magnetic data may be a useful tool for mapping surficial sediments. These magnetic data provide the first offshore evidence for the direction of major water discharge. It remains unclear whether the valleys were formed by river incision during one or several regional lowstand(s) or from one or several sub-glacial discharge episode(s) across the Magdalen Plateau. The valley evidence should be incorporated into any future palaeogeographical reconstructions.

Holocene paleoenvironment of the Nihewan Basin, China, inferred from high-resolution luminescence dating and a multiproxy analysis of gully sediments

Holocene paleoenvironment of the Nihewan Basin, China, inferred from high-resolution luminescence dating and a multiproxy analysis of gully sediments