Magnetic Susceptibility Values Research Articles

Effect of graphene on the key electrical, optical, and magnetic properties of polymethylmethacrylate: a study based on molecular modeling.

In this work, a new polymeric structure was designed consisting of a nanometric sheet of graphene (G) and a polymethylmethacrylate (PMMA) repeat unit, which was designated as PMMA-G. Three degrees of polymerization of PMMA-G were considered: monomer (PMMA-G1), dimer (PMMA-G2), and trimer (PMMA-G3). The effect of incorporating a nanometric sheet of graphene into the molecular structure of PMMA on the modification of some of its main optical, magnetic, and electrical properties was investigated. Currently, the study presented here is of great relevance since various areas of technology require new materials with specific properties for the development of new devices. The results of our study reveal that the dielectric constant of PMMA is reduced when graphene is incorporated. However, a percentage increase of 14.48% in the refractive index of PMMA when graphene is inserted to form the nanocomposite is observed. It is found that the absolute value of molar magnetic susceptibility of PMMA increases considerably when reinforced with graphene. Finally, when reinforcing PMMA with graphene to obtain the PMMA-G nanocomposite, the electrical resistivity increases by almost an order of magnitude. We used computational tools under Materials Studio (MS) software. We built a PMMA molecule with three degrees of polymerization, graphene sheet, and polymethylmethacrylate-graphene composite (PMMA-G) was built also with three degrees of polymerization using a concentration of 50% graphene over the PMMA polymer. For each structure, we used computational code DMol3 of MS, which is based on the Density Functional Theory, and the geometry optimization process was carried out to obtain the most stable structures. Finally, using the connectivity indices method together with topological properties of the molecular structures, implemented in Synthia computational code of MS software, we calculated the dielectric constant, magnetic susceptibility, refractive index, and electrical resistivity, for pure PMMA and PMMA-G structures for their three degrees of polymerization. The results were analyzed, and the changes in these properties were discussed in terms of the effect of an electric and magnetic field on the molecular structures of PMMA-G with respect to PMMA.

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

As a pivotal region for studying early human occupation in East Asia, the Nihewan Basin has witnessed numerous studies on Paleolithic sites and associated paleoenvironmental records. However, little attention has been given to the Holocene period, despite the basin being a crossroads for the exchange of NE China Neolithic cultures. In the central part of the Nihewan Basin, we found a gully sediment section with a thickness of ∼9 m, which exhibits clear parallel bedding throughout. The section is composed of ten sediment layers (Layers 10–1 from bottom to top), from which three distinct dark-colored soil layers (Layers 8, 4 and 2) and two erosion surfaces (between Layers 10 and 9, and Layers 2 and 1) were identified. Forty-four sediment samples from the section were optically dated, and the obtained ages were refined using Bayesian statistical modeling. The age-depth relationship and sedimentary characteristics suggest that the sedimentation process of Layers 9–2 was continuous. To reconstruct the paleoenvironment, the grain-size distribution, magnetic susceptibility, and pollen content of the sediments were analyzed. The three soil layers exhibit high magnetic susceptibility values. Based on these climatic proxies, five climate stages were recognized. From ∼12.7 to ∼6.8 ka, the climate in the basin region was cold and dry. The period between ∼6.8 and ∼5.4 ka was marked by optimal climate conditions that led to soil formation. Subsequently, the climate was colder and drier during the period of ∼5.4 – ∼4.0 ka, and transitioned to warm and wet conditions again from ∼4.0 to ∼2.7 ka. Another stage of soil formation occurred between ∼2.7 and ∼1.7 ka, during which the climate was predominantly warm and humid, albeit punctuated by a brief interval of colder and drier conditions. These climate variations coincided with cultural evolution stages within the basin, highlighting a close relationship between environmental change and human adaptation.

Susceptibility and Metallics Elements in Soil Struck by Lightning in West Kotawaringin Regency, Central Kalimantan

Abstract Magnetic susceptibility is a magnetic parameter that assesses a magnetic material’s susceptibility to external magnetic fields. Magnetic susceptibility values can determine the properties of magnetic minerals related to the elements they contain. This research aims to determine the value of magnetic susceptibility and metal element content in soil struck by lightning in West Kotawaringin Regency. Sample measurements were performed using the Bartington MS2B instrument to determine the magnetic susceptibility value and XRF (X-ray fluorescence) to determine the metal element content in the soil samples. The magnetic susceptibility value obtained for sample A with low frequency (<10 strikes per month) was 26.1 x 10−8 m 3/kg; for sample B with medium frequency (11–200 strikes per month), it was 538.4 x 10−8 m 3/kg; and for sample C with high frequency (>20 strikes per month), it was 24.4 x 10−8 m 3/kg. Fe (388,000 mg/kg) was the most prevalent metal element in samples B and C, while element V (300 mg/kg) was the least prevalent in sample A. The sample with the highest metal element content was Fe (388,0 mg/kg), while sample A had the lowest metal element content, V (300 mg/kg). The highest correlation value between magnetic susceptibility and metals is 0.9 (K); 0.96 (Cr); 0.98 (Fe); and 1.00 (Ca, Ni, Zn, and Re).

Integrated Magnetic and Geochemical Assessment of the Soil from the Steam Power Plant Area of South Kalimantan Province

Abstract The magnetic proxy approach has proven to be efficient in the assessment of pollution by potentially toxic elements when targeting soils or areas with a homogeneous background where anthropogenic magnetic signals can be easily distinguished. It’s crucial to conduct research on the impact of fly ash on the vicinity of the PLTU in this particular area, as it’s a previously unexplored area. The unique thing about this research is that this PLTU uses coal containing Fe, Pb, and Mg as fuel and has a fairly high susceptibility value for fly ash and bottom ash. This study is due to an analysis of the magnetic susceptibility and heavy metal content in the soil of the area around the Asam-Asam steam power plant (PLTU) of South Kalimantan Province, where geogenic input and fly ash can influence it. Heavy metals that have passed the threshold at all locations are Ti, Cr, Mn, Fe, Ni, Cu, V, and Al. Most of the correlation coefficients are strong and significant between magnetic susceptibility values and heavy metal concentrations at each location. The correspondence between magnetic susceptibility values and heavy metal content reflects the potential of magnetic proxy methods at polluted spots, provided that the lithological conditions are carefully considered.

Late Holocene extraordinary palaeoflood events and their climatological context in the Shahe River, Huaihe River Basin, China

Palaeoflood events represent immediate hydrological responses to extreme climate change. A loess-paleosol sedimentary profile containing three overbank flood deposits (OFD1, OFD2, and OFD3) layers that recorded palaeoflood events was discovered on the platform scarp of the Shahe River, a tributary of the Huaihe River through a field investigation. Sediment samples were collected, and their physicochemical properties, as well as optically stimulated luminescence (OSL) dating, were analyzed. The results indicated that OFD1, OFD2, and OFD3 were indeed overbank flood deposits influenced by hydrodynamic forces. However, OFD3 and OFD1 consisted primarily of sand (>60 %) in terms of particle size composition, whereas paleosol (S0), transitional loess (Lt), and Malan loess (L1) mainly comprised silt (>70 %). Moreover, the magnetic susceptibility values of OFD3 and OFD1 exceeded those of S0, Lt, and L1. The contents of Na2O, K2O, and SiO2 were higher, while their contents of Al2O3 and Fe2O3 were lower in OFD3 and OFD1. These suggested that OFD3 and OFD1 may originate from weathered bedrock materials transported from the upper reaches of the Shahe River under significant hydrodynamic forces. The particle size composition, magnetic susceptibility value, and geochemical element composition of OFD2 were similar to those of S0, Lt, and L1 but diverged significantly from those of OFD1 and OFD3, indicating that OFD2 originated from loess and soil sediments widely distributed on both sides of the valley. Through OSL dating and stratigraphic chronological framework of the sedimentary profile, these three extraordinary palaeoflood events in the Huaihe River Basin occurred during the late Holocene, ∼1470 a. The analysis of high-resolution climate proxy indicators, atmospheric circulation factors, and global mean temperature demonstrated a direct correlation between these extreme flood events and abrupt climate changes during ∼ 1470 a. This period corresponded to severe climate deterioration during the Northern and Southern Dynasties (589–420 CE) in China. These findings are crucial for enhancing our understanding of regional hydrological climate responses to global changes.

Differentiating calcifications from cerebral microbleeds using quantitative susceptibility mapping.

To differentiate cerebral microbleeds (CMBs) and calcifications using quantitative susceptibility mapping (QSM). CMBs were visualized and located using QSM from susceptibility-weighted imaging data collected on a 3-T MR scanner. Calcifications of the pineal gland and the choroid plexus were localized first using CT. All calcifications and CMBs were assessed using QSM to evaluate their magnetic susceptibility. The distribution of the magnetic susceptibility for the CMBs was determined and the CT attenuation was correlated with the mean magnetic susceptibility for the calcifications. A total of 232 hypointense foci were selected from the QSM data: 121 were CMBs and 111 were calcifications. The mean magnetic susceptibility was -214 ± 112 ppb for the calcifications and 392 ± 204 ppb for the CMBs. The minimum value of magnetic susceptibility was 75 ppb for all the CMBs and the maximum value was -52 ppb for all the calcifications. The calcifications were clearly differentiable from the CMBs from the sign alone (p < 0.001). The magnetic susceptibility for the CMBs was 299 ± 133 ppb in the lobar subcortical white matter and 499 ± 220 ppb for deep CMBs in the basal ganglia, thalamus, and brainstem. There was a significant difference in the susceptibility between these two regions (p < 0.001). The sign of the magnetic susceptibility was sufficient to differentiate calcifications and CMBs. The concentration of calcium or iron can be determined from the susceptibility value itself. The deep CMBs had higher susceptibility on average than lobar bleeds. This study's ability to differentiate between CMBs and calcifications using QSM could enhance diagnostic accuracy, guiding more precise treatment decisions for stroke or tumor patients. The sign of magnetic susceptibility is sufficient to differentiate calcifications and CMBs. QSM can successfully differentiate calcifications from microbleeds. The concentration of calcium or iron can be determined from the susceptibility value itself.

Topographical metal burden correlates with brain atrophy and clinical severity in Wilson's disease

BackgroundQuantitative susceptibility mapping (QSM) is a post-processing technique that creates brain susceptibility maps reflecting metal burden through tissue magnetic susceptibility. We assessed topographic differences in magnetic susceptibility between participants with and without Wilson's disease (WD), correlating these findings with clinical severity, brain volume, and biofluid copper and iron indices. MethodsA total of 43 patients with WD and 20 unaffected controls, were recruited. QSM images were derived from a 3T MRI scanner. Clinical severity was defined using the minimal Unified Wilson's Disease Rating Scale (M-UWDRS) and Montreal Cognitive Assessment scoring. Differences in magnetic susceptibilities between groups were evaluated using general linear regression models, adjusting for age and sex. Correlations between the susceptibilities and clinical scores were analyzed using Spearman's method. ResultsIn age- and sex-adjusted analyses, magnetic susceptibility values were increased in WD patients compared with controls, including caudate nucleus, putamen, globus pallidus, and substantia nigra (all p < 0.01). Putaminal susceptibility was greater with an initial neuropsychiatric presentation (n = 25) than with initial hepatic dysfunction (n = 18; p = 0.04). Susceptibility changes correlated negatively with regional brain volume in almost all topographic regions. Serum ferritin, but not serum copper or ceruloplasmin, correlated positively with magnetic susceptibility level in the caudate nucleus (p = 0.04), putamen (p = 0.04) and the hippocampus (p = 0.03). The dominance of magnetic susceptibility in cortical over subcortical regions correlated with M-UWDRS scores (p < 0.01). ConclusionThe magnetic susceptibility changes could serve as a surrogate marker for patients with WD.

Characteristics of the Density and Magnetic Susceptibility of Pumice from the Maninjau Caldera-Forming Eruption, Indonesia

Abtract- Lake Maninjau is a volcanic caldera formed by a volcanic eruption located in West Sumatra. This volcanic eruption threw pyroclastic materials, one of which is pumice, as far as ± 75 km from the center of the eruption. This study aims to determine density and magnetic susceptibility characteristics of pumice from maninjau caldera-forming eruptions, indonesia. The method used is the rock-magnetic method. It is used to measure magnetic susceptibility based on the distribution of volcanic material. The samples were selected from 3 different locations around Mount Maninjau with distances varying between ±12-32 km. A Bartington Magnetic Susceptibility Metre Type B (MS2B) instrument was utilised to determine the susceptibility of rocks and X-ray fluorescence (XRF) to identify rock element levels. The results of the data analysis obtained have magnetic density and susceptibility values in the NGS (Ngarai Sianok) area, which ranged from 0.67-1.77×103 kg/m3 and 4.4-826×10-8m3/kg, the LBS (Lubuk Basung) area which ranged of 0.74-1.34×103 kg/m3 and 6.6-625.4×10-8m3/kg, and the PRM (Pariaman) area, which ranged from 0.68-3.63×103 kg/m3 and 8-359×10-8m3/kg. The results showed that when sampling closer to Mount Maninjau, the pumice is characterized by dense, fresh, but very small pore size and dominated by slightly greyish white pumice with few white crystals on its surface. Therefore, the location of the pumice from Mount Maninjau has a significant influence on its characteristics, including density, magnetic susceptibility, and iron (Fe) and titanium (Ti) content. Keywords: Pumice, Density, Magnetic Susceptibility, Mount Maninjau, XRF

Application of soil magnetometry and geochemical methods to investigate soil contamination with antimony

The aim of the study was an assessment of the pollution level and identification of the antimony sources in soils in areas subjected to industrial anthropopressure from: transport, metallurgy and electrical waste recycling. The combination of soil magnetometry, chemical analyzes using atomic spectrometry (ICP-OES and ICP-MS), Sb fractionation analysis, statistical analysis (Pearson’s correlation matrix, factor analysis) as well as Geoaccumulation Index, Pollution Load Index, and Sb/As factor allowed not only the assessment of soil contamination degree, but also comprehensive identification of different Sb sources. The results indicate that the soil in the vicinity of the studied objects was characterized by high values of magnetic susceptibility and thus, high contents of potentially toxic elements. The most polluted area was in the vicinity of electrical waste processing plants. Research has shown that the impact of road traffic and wearing off brake blocks, i.e. traffic anthropopression in general, has little effect on the surrounding soil in terms of antimony content. Large amounts of Pb, Zn, As and Cd were found in the soil collected in the vicinity of the heap after the processing of zinc–lead ores, the average antimony (11.31 mg kg−1) content was lower in the vicinity of the heap than in the area around the electrical and electronic waste processing plant, but still very high. Antimony in the studied soils was demobilized and associated mainly with the residual fraction.

3D Gravity and magnetic inversion modelling for geothermal assessment and temperature modelling in the central eastern desert and Red Sea, Egypt

The Central Eastern Desert and Red Sea region have emerged as a significant area of interest for geothermal energy exploration, owing to their unique geological characteristics and active tectonic activity. This research aims to enhance our understanding of the region's geothermal potential through a comprehensive analysis of gravity and magnetic data. By utilizing a 3D gravity inversion model, a detailed examination of subsurface structures and density variations was conducted. Similarly, a 3D magnetic inversion model was employed to investigate subsurface magnetic properties. Integration result from the Pygimli library ensured robustness and accuracy in the inversion results. Furthermore, a temperature model was developed using the WINTERC-G model and inversion techniques, shedding light on the thermal structure and potential anomalies in the study area. The analysis of the Bouguer gravity map, 3D gravity inversion model, and magnetic data inversion yielded significant findings. The Red Sea exhibited higher gravity values compared to the onshore Eastern Desert, attributed to the presence of a thinner and denser oceanic crust as opposed to the less dense continental crust in the Eastern Desert. The 3D gravity inversion model revealed distinct variations in density, particularly high-density zones near the surface of the Red Sea, indicating underlying geological structures and processes. Conversely, density gradually decreased with depth along the onshore line, potentially influenced by a higher concentration of crustal fractures. The magnetic data inversion technique provided additional insights, highlighting areas with demagnetized materials, indicative of elevated temperatures. These findings were consistent with the correlation between high-density areas and low magnetic susceptibility values, reinforcing the proposition of increased heat transfer from the Red Sea. Comparative analysis of temperature profiles further confirmed the presence of elevated temperatures in promising zones, emphasizing the geothermal potential associated with heat transfer from the Red Sea.This research contributes to the understanding of the geothermal resources in the Central Eastern Desert and Red Sea region. The results from gravity and magnetic data inversions, combined with temperature profiles, provide valuable information for future geothermal exploration and utilization efforts. The findings underscore the importance of geothermal energy in achieving sustainability and contribute to the global discourse on renewable energy sources.

The deformed alkaline Balda granite (Northern Cameroon): A witness of back-arc basin in the northern part of Central African Orogenic Belt

Located on the border between the NW Cameroon and Mayo-Kebbi domains in northern Cameroon, the Balda pluton is a deformed alkaline granite. Due to its unique location and geological features, it holds crucial information for understanding the evolution of the Central African Orogenic Belt (CAOB), which remains poorly understood. This multidisciplinary study combines field data, microscopic observations, Anisotropy of Magnetic Susceptibility (AMS), and U-Pb zircon dating to constrain the geodynamic evolution of the CAOB.The Balda pluton is a NNE-SSW elongated pluton consists mainly of aegirine-riebeckite granite and leucogranite. It displays diverse magnetic susceptibility values (Km) spanning from 0.19 x 10-3 to 21.98 x 10-3. Notably, 93 % of the Km values exceed 5 × 10-4SI, indicating a prevalence of mixed paramagnetic and ferromagnetic mineralogy (such as magnetite-rich). This observation is supported by microscopic examinations and K-T curves. An analysis of AMS unveils high P% values (2.8 to 58.7 %, with a mean of 15 %) and prevalent oblate magnetic fabrics (68 %). The magnetic foliation generally aligns with the field foliation and has steep dips ranging from NNE to NE or from SSW to SW and magnetic lineations exhibit shallow plunges (<35°) from SSW to SW. Microscopic analysis reveals high-temperature, solid-state deformation microstructures, indicating post-emplacement deformation processes and the presence of kinematic markers consistent with sinistral shear. Zircon grain analysis reveals two distinct types: “bright” and “dark.” These types differ in both their appearance under cathodoluminescence and their chemical composition. Bright zircons yield a U-Pb age of 732.7 ± 7.5 Ma, interpreted as the pluton emplacement age. Dark zircons are younger (ca. 680 Ma), suggesting a later tectono-metamorphic or alteration event.The integration of these results in a larger geodynamic context suggests that the Balda pluton formed within a syn-orogenic extensional back-arc basin. This emplacement was followed by significant post-emplacement deformation characterized by sinistral simple shear-dominated transpression likely related to the continental collision (ca. 680 Ma) of the NW Cameroon and Mayo-Kébbi domains.

THE VARIATIONS OF CLINKER SUPERPARAMAGNETIC VALUE FROM PT. SEMEN PADANG BY USING A BARTINGTON MAGNETIC SUSCEPTIBILITY METER SENSOR TYPE B

Clinker is an important material in the cement making process. Before clinker is formed, the raw material is burned in a Rotary Kiln at a temperature of up to 1450°C, then cooled in a Greet Cooler to a temperature of 100°C and produces clinker. This research is to determine variations in the superparamagnetic value of clinker based on the magnetic susceptibility value. The method is the rock magnetism method using theMS2B. Clinker samples are takenhourly every day from the Semen Padang Factory. The 휒푙푓value obtained varies between 3.2×10-8m3/kg to 22.6×10-8m3/kg. The superparamagnetic values obtained also varied, ranging from 0.0%-7.4%. Based on the 휒푓푑%obtained, there were 136 clinker samples containing less than 10% superparamagnetic grains, and 32 samples includedthe 휒푓푑%medium had a percentage of 2%-10% where the samples contained superparamagnetic grains. Between 10% and 75% is a mixture of fine and coarse superparamagnetic grains.

New Nanosized V(III), Fe(III), and Ni(II) Complexes Comprising Schiff Base and 2-Amino-4-Methyl Pyrimidine: Synthesis, Properties, and Biological Activity.

A new synthesis of mixed ligand complexes vanadium(III), iron(III), and nickel(II), [M : L1 : L2], where L1 = Schiff base 2-((E)-((4-(((E)-benzylidene)amino)phenyl)imino)methyl)-naphthalene-1-ol (C24H18N2O) as for L2 = AMPY 2-amino-4-methyl pyrimidine (C5H7N3) were prepared in powder and investigated. Element analysis, molar conductivity, FT-IR, UV-vis, and magnetic susceptibility values have been acquired to describe the generated complexes. The values of vanadium(III), iron(III), and nickel(II) compounds are, respectively, 2.88 BM, 5.96 BM, and 2.92 BM, demonstrating that all compounds conform to the recommended octahedral geometry. Thermal gravimetric analysis (TGA) is used to further assess the complexes and establish the temperature stability and degradation of the metal complexes. The calculations abstracted from XRD patterns propose nanosized complexes (average size 29-50 nm). The microstructures of the samples have also been investigated by scanning electron microscopy (SEM). The disc diffusion method was used to assess and analyze the inhibition of the growth of compounds against harmful bacterial and fungal strains. The prepared complexes were tested against three strains of bacteria, one gram-positive strain (Bacillus subtilis), two gram-negative strains (Escherichia coli and Pseudomonas aeruginosa), and one fungus (Aspergillus fumigatus). The complexes inferred antimicrobial activity against the studied organisms. Specifically, vanadium(III) and nickel(II) are more effective than iron(III), making them promising drugs.

Finding an analytical solution for the cylinder’s fluxmetric demagnetizing factor using spherical harmonics

The work examines an analytical solution for calculating the fluxmetric demagnetizing factor of cylindrical magnets at large values of magnetic susceptibility and an arbitrary value of elongation. The application of the analytical solution for calculating the demagnetizing factor significantly simplifies the modeling and calculation of magnetic characteristics of cylindrical technical objects. A simplified analytical model of the scalar potential of the magnetic field of a cylinder with infinite magnetic favorability, inductively magnetized in a uniform magnetic field, was constructed using an approximate representation of the distribution of fictitious magnetic charges on its surface. The method of spherical harmonic analysis for the magnetic field was used, which made it possible to obtain an analytical representation of the demagnetization field in the central cross section of the cylinder. Limitation of the harmonic series of this representation by seven first harmonics is proposed, and an additional amplitude factor is applied to correct the contribution of the first harmonic to the demagnetization field. This made it possible to compensate for the distortion of the magnetic field near the ends of the cylinder and bring the simplified analytical model closer to the target mathematical model with a uniform demagnetization magnetic field. The reliability of the results of calculating the fluxmetric demagnetizing factor according to the derived formula was evaluated by comparing them with the known results obtained using the numerical method of calculation and according to empirical formulas. It is shown that the proposed approach makes it possible to obtain reliable results of calculating the fluxmetric demagnetizing factor with a deviation of up to 5 % at infinite favorability in the range of cylinder elongation values from 0.01 to 500

Compressive Strength Analysis of Mortar Made from Volcanic Sand in Nagari Aia Angek Based on Magnetic Mineral Content

Mortar is a binder or adhesive with a standard viscosity of ingredients (water, cement, and sand). Mortar made has strength, mortar strength is measured using Cement Compression testing machine. Sand in mortar making contains magnetic minerals such as magnetite (Fe3O4) or Fe2+3Fe+2O4-2, hematite mineral (α-Fe2O3) which will be measured for magnetic susceptibility value using Bartington Magnetic Susceptibility Meter Sensor Type B (MS2B). To determine the concentration of magnetic minerals and their relationship with mortar compressive strength, the rock magnetism method was used. Measurement of sand samples of Kamumuan River, Sungai Limau District using Bartington Magnetic Susceptibility Meter Sensor Type B (MS2B) by categorizing sand into 3 treatment, namely Addition of magnetic minerals (PTM) with χLF value 3863.3 x 10-8m3/kg and χFD (%) 0.72, reduction of magnetic minerals (PKM) with χLF value 1920 x 10-8m3/kg and χFD (%) 0.79, normal magnetic minerals (PM) with χLF value 2334.7 x 10-8m3/kg and χFD (%) 0.62. The sample has a grain type that is almost no superparamagnetic grain and has antiferromagnetic properties. Samples grouped by treatment were made into mortar and tested using a cement compression testing machine with the results of mortar compressive strength, namely ATM of 49.4 Kg/cm², AKM of 46.6 Kg/cm², and AM 52.3 Kg/cm². Based on the analysis conducted, the magnetic minerals contained in the sand affect the results of the compressive strength of the mortar, the higher the susceptibility value in the sand, the stronger the compressive strength of the mortar

Combined diffusion tensor imaging and quantitative susceptibility mapping to characterize normal-appearing white matter in self-limited epilepsy with centrotemporal spikes.

In brain development, Myelination is the characteristic feature of white matter maturation, which plays an important role in efficient information transmitting. The white matter abnormality has been reported to be associated with self-limited epilepsy with centrotemporal spikes (SeLECTS). This study aimed to detect the altered white matter region in the SeLECTS patients by the combination of diffusion tensor imaging (DTI) and quantitative susceptibility mapping (QSM) technique. 27 children with SeLECTS and 23 age- and gender-matched healthy children were enrolled. All participants were scanned with 3.0-T MRI to acquire the structure, diffusion and susceptibility-weighted data. The susceptibility and diffusion weighted data were processed to obtain quantitative susceptibility map and fraction anisotropy (FA) map. Then voxel-wise tract-based spatial statistics (TBSS) were used to analyze quantitative susceptibility and FA data. Both DTI and QSM revealed extensive white matter alterations in the frontal, parietal, and temporal lobes in SeLECTS patients. The overlapped region of DTI and QSM analyses was located in the fiber tracts of the corona radiata. The FA values in this overlapped region were negatively correlated with the magnetic susceptibility values. Our results suggest that TBSS-based QSM can be employed as a novel approach for characterizing alterations in white matter in SeLECTS. And the combination of QSM and DTI can provide a more comprehensive evaluation of white matter integrity by utilizing different biophysical features.

Silicate weathering linked with global climate change along the Mid-Pleistocene transition: A record from the Himalayan foreland Basin, India

Tectonic uplift and climate change play a pivotal role in controlling silicate weathering in the source region. Being adjacent to the hinterland, the sediments of the Himalayan foreland basin (HFB) hold an excellent archive to elucidate weathering link with climate and uplift. In this study, we present geochemical records of major, trace and rare earth elements, clay mineral compositions as well as the environmental magnetic and stable carbon isotope composition (δ13C) of siliciclastic sediments of the HFB over the past 2.0 Ma. These records have been used to link silicate weathering with global climate change along the Mid-Pleistocene Transition (MPT) period. The source rock compositions are characterized by selected elemental ratios, i.e., Cr/Th, Th/Sc, Th/Co and La/Sc as well as other geochemical proxies such as Al2O3/TiO2 and TiO2/Zr, suggesting a felsic source rock composition. The enriched LREE pattern of Chondrite-normalised REE with a negative Europium anomaly also attributes to felsic source rock composition. All these inferences suggest that most of the studied sediments were derived from mixed sources of the Higher Himalayan rocks and the Lesser Himalayan crystalline regions. A declining trend in kaolinite/(illite + chlorite) ratios, decreasing values of geochemical weathering indices (such as Rb/Sr and CIA), a decrease in magnetic susceptibility and gradual depleted value of δ13C indicate a decrease in chemical weathering of the siliciclastic rocks in the source region, which is most probably associated with the global climate change from warm-humid to cold-dry condition along the MPT. This suggests that variation in silicate weathering in the Himalayan region are mainly controlled by global climate and monsoon conditions.

Longitudinal Changes in Iron and Myelination Within Ischemic Lesions Associate With Neurological Outcomes: A Pilot Study.

Combined quantitative susceptibility mapping and R2* relaxometry can distinguish iron and myelin components in ischemic lesions. We aimed to investigate whether longitudinal changes in magnetic susceptibility and R2* values within ischemic lesions were associated with neurological outcomes. In this single-center prospective study, we included patients, 20 to 90 years of age, who were consecutively admitted to the stroke care unit between August 2020 and March 2022 due to acute ischemic stroke. The participants underwent 2 instances of quantitative susceptibility mapping and R2* relaxometry scanning before and after stroke rehabilitation. We compared the changes in these quantitative measures across different subtypes of acute ischemic stroke. Multiple linear regression models were used to investigate the associations between the National Institutes of Health Stroke Scale scores and the mean magnetic susceptibility and R2* values in ischemic lesions. Among a total of 112 patients with acute ischemic stroke, 32 participants (aged 73.3±9.4 years; 20 men and 12 women) were evaluated. The median time from stroke onset to the first imaging was 5 days and that to the second imaging was 102 days. The changes in magnetic susceptibility values of branch atheromatous disease were higher than those of cardioembolism (mean difference, 0.018 [95% CI, 0.009-0.027] ppm; P<0.001) and lacunar (mean difference, 0.013 [95% CI, 0.005-0.020] ppm; P=0.004). Across all patients, the changes in National Institutes of Health Stroke Scale scores were associated with those of magnetic susceptibility values (coefficient, 0.311 [95% CI, 0.098-0.520]; P=0.017) but not with R2* values (coefficient, 0.114 [95% CI, -0.127 to 0.345]; P=0.291). The longitudinal changes in the magnetic susceptibility values within ischemic lesions were associated with neurological outcomes during the restorative stages poststroke in patients experiencing acute ischemic stroke. URL: https://www.umin.ac.jp/ctr/; Unique identifier: UMIN000050719.

Interscanner reproducibility of volumetric quantitative susceptibility mapping about cerebral subcortical gray nuclei at different MR vendors with the same magnetic strength.

Quantitative susceptibility mapping (QSM) technique was a new quantitative magnetic resonance imaging technique to evaluate the cerebral iron deposition in clinical practice. The current study was aimed to investigate the reproducibility of the volumetric susceptibility value of the subcortical gray nuclei at two different MR vendor with the same magnetic strength. Cerebral magnitude and phase images of 21 normal subjects were acquired from a 3D multiecho enhanced gradient recalled echo sequence at two different 3.0T MR scanner, and then the magnetic susceptibility images were generated by STI software. The brain structural images were coregistered with magnitude images and generated the normalized parameters, and then generated the normalized susceptibility images. The subcortical gray nuclei template was applied to extract the volumetric susceptibility value of the target nuclei. ICC value (95% CI) of the caudate, putamen and GP were 0.847 (0.660-0.935), 0.848 (0.663-0.935) and 0.838 (0.643-0.931), respectively. The ICC value of the thalamus was 0.474 (0.064-0.747). Ninety-five point two percent (20/21) of the difference points of the susceptibility located between the 95% LA for the caudate at the two different 3.0T MR scanner, while the less than 95% of the difference points of the susceptibility value located between the 95% LA for the putamen, globus pallidus and thalamus. The current study identified that the caudate had the stable reproducibility of the magnetic susceptibility value, and the other basal ganglion nuclei should be cautious for the quantitative evaluation of the magnetic susceptibility value at different 3.0T MR scanner.

The potential of low-destructive characterization of archaeological sites with stony and eroded soils through geostatistics at the Celtic oppidum of Bibracte (France)

Urbanization during Europe's Late Iron Age brought about a rise of enclosed settlements, or ‘oppida’. These centers of human activity left indelible marks on the environment, influencing its geochemistry. The key goal of the research is to identify zones of anthropogenic activities within eroded and stony soils of the Bibracte oppidum’s ‘empty spaces’. We demonstrate an innovative multivariate and geostatistical approach to integrate relevant geochemical and, when available, geophysical records, thereby facilitating a comprehensive understanding of activity areas within oppida in conditions of soil truncation, erosiona and uneven distribution of cores. Our results indicate varied and potentially intensive past human activities in the southern area of La Terrasse, La Chaume, Le Porrey and Le Verger. This is evidenced by elevated values of magnetic susceptibility and chemical elements such as phosphorus and calcium, which reflect here a diverse historical utilization of these spaces. Our robust multivariate statistical analysis effectively deals with the challenges posed by irregular spatial distribution and missing data, enabling the successful correlation of geochemical and geophysical data and providing compelling evidence of spatially differentiated human activities throughout the oppidum. This extends our understanding of Iron Age urbanization and the nuanced utilization of space within these early urban centers.