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AbstractFive new copper(II) complexes of substituted quinoxaline ligands have been prepared and characterized via single crystal X-ray diffraction, including [Cu(5-Mequinox)2(NO3)2] (2), [Cu(5-Mequinox)(NO3)(H2O)(μ-1,3-NO3)]n (3), the chloride salt (5-MequinoxH)2[Cu3Cl8] (4), the complex [Cu(6-Mequinox)2(NO3)2] (5) and [(2-carboxylato-3-methylquinox)(2-hydroxymethyl-3-methylquinox)nitratocopper(II)]. CH3CN (6) [quinox = quinoxaline; 5-Mequinox = 5-methylquinoxaline; 6-Mequinox = 6-methylquinoxaline]. None of the complexes produced diazine bridged chain structures (as seen in [(quinox)Cu(NO3)2]n (1)), although 3 forms chains via a bridging nitrate ion. Crystal packing is controlled primarily through hydrogen bonding and π-stacking of nitrate ions. The temperature dependent magnetic susceptibility data of the parent compound [(quinox)Cu(NO3)2]n are also reported and discussed. [ABSTRACT FROM AUTHOR]

Polyradical cages are of great interest because they show very fascinating physical and chemical properties, but many challenges remain, especially for their synthesis and characterization. Herein, we present the synthesis of a polyradical cation cage 14⋅+ through post‐synthetic oxidation of a redox‐active phenothiazine‐based Pd2L4‐type coordination cage 1. It′s worth noting that 1 exhibits excellent reversible electrochemical and chemical redox activity due to the introduction of a bulky 3,5‐di‐tert‐butyl‐4‐methoxyphenyl substituent. The generation of 14⋅+ through reversible electrochemical oxidation is investigated by in situ UV/Vis‐NIR and EPR spectroelectrochemistry. Meanwhile, chemical oxidation of 1 can also produce 14⋅+ which can be reversibly reduced back to the original cage 1, and the process is monitored by EPR and NMR spectroscopies. Eventually, we succeed in the isolation and single crystal X‐ray diffraction analysis of 14⋅+, whose electronic structure and conformation are distinct to original 1. The magnetic susceptibility measurements indicate the predominantly antiferromagnetic interactions between the four phenothiazine radical cations in 14⋅+. We believe that our study including the facile synthesis methodology and in situ spectroelectrochemistry will shed some light on the synthesis and characterization of novel polyradical systems, opening more perspectives for developing functional supramolecular cages. [ABSTRACT FROM AUTHOR]

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3‐6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa21–22). The physical properties like density (3.34 g cm−3) and magnetic susceptibility (logχ <5.0, with χ in 10−9 m3 kg−1) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near‐surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock‐darkened fragments, and (e) clasts of various types of impact melts but no solar wind‐implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25–40 cm, is ~17–20 Myr. [ABSTRACT FROM AUTHOR]

Perovskite-like compounds have attracted great attention because of their good properties, such as electrical, optical, and magnetic properties, etc. Herein, a new perovskite-like anionic dicyanamidometallate, namely (Bu3MeP)[Ni(dca)3] (1) (Bu3MeP = tributylmethylphosphine cation, dca = dicyanamide), was synthesized and structurally characterized by elemental analysis, IR spectrum, thermogravimetric analysis, and single-crystal X-ray diffraction. The compound crystallizes in the tetragonal crystal system with the chiral space group P43212, and exhibits a three-dimensional anionic dicyanamidometallate framework from Ni2+ units bridged by dicyanamides, in which tributylmethylphosphine cations are accommodated in the voids. The butyl groups present two conformations in the tributylmethylphosphine cation, resulting in chirality character occurred in compound 1. Variable-temperature magnetic susceptibility analysis indicates that weak ferromagnetic interaction exists between the nickel(II) ions coupling by µ1,5-bridings. [ABSTRACT FROM AUTHOR]

Members of the solid solutions CePt1–xAuxAl have been synthesized from the elements and pure samples could be obtained for the whole range of x from 0.1–0.9. Powder X-ray diffraction patterns indicated the TiNiSi-type structure (orthorhombic, space group Pnma) for the whole series, consistent with the end members CePtAl and CeAuAl. The lattice parameters and therefore also the unit cell volumes evolve in a linear fashion when going from CePtAl to CeAuAl. Magnetic susceptibility and magnetization investigations were performed for the compounds with x = 0.1, 0.2, 0.3, 0.5, 0.7 and 0.9. The results show that the ferromagnetic ground state of CePtAl gets destabilized for small degrees of substitution (x = 0.1) resulting in a lower Curie temperature. For larger values of x, changes towards an antiferromagnetic ground state are observed, in line with pure CeAuAl. [ABSTRACT FROM AUTHOR]

A dichlorophenyl substituted nitronyl nitroxide radical 2-(2,6-dichlorophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (L) is prepared, its structure and magnetic properties are studied. It is shown that the interaction of bis(hexafluoroacetylacetonato)copper(II) [Cu(hfac)2] with L leads to the formation of the {[Cu(hfac)2][Cu(hfac)2L2]} heterospin complex whose crystal structure consists of pseudo-polymer chains formed by alternating single-spin [Cu(hfac)2] and three-spin [Cu(hfac)2L2] fragments. It is established that the temperature dependence of magnetic susceptibility of {[Cu(hfac)2][Cu(hfac)2L2]} is determined by ferromagnetic exchange interactions between unpaired electrons of Cu(II) ions and the axially coordinated L in three-spin fragments. [ABSTRACT FROM AUTHOR]

Extensional flow is vital in droplet dynamics, influencing their formation, size, stability, and functionality across diverse applications from industrial processes to biomedical technology. Ferrofluid droplets are pivotal in many such applications, where magnetic fields enable non-contact manipulation without undesirable heating effects. However, controlling ferrofluid droplet dynamics in magnetically influenced extensional flows is challenging due to the complex interplay of induced magnetization, intrinsic magnetic properties, and flow kinematics. Here, we present a first-principle-based theory delving into the morphology of a ferrofluid droplet under the combined influence of an external magnetic field and extensional flow. Unlike previous studies, we employ an asymptotic analysis that delves on the shape alterations by considering local magnetization as dependent on magnetic field intensity. Additionally, we develop a numerical model based on phase-field hydrodynamics to establish the practical applicability of the asymptotic solution and to explore large droplet-deformation regimes. The study demonstrates that increasing the magnetic field intensity, the saturation magnetization of the ferrofluid, and the initial magnetic susceptibility each independently improve droplet deformation. Additionally, we found that in a uniform magnetic field, the extensional viscosity of a ferrofluid emulsion is influenced by the strain rate, leading to strain-thickening behavior in the dilute emulsion. Our findings offer new insights into field-assisted manipulation of ferrofluid droplets, emphasizing their potential in applications ranging from process engineering to biomedical technology. [ABSTRACT FROM AUTHOR]

Monitoring atmospheric pollution in urban areas is challenging because pollutant deposition occurs at short distances, requiring a large amount of sampling and analysis to characterize it. Ecological indicators can help overcome this problem, allowing us to select sites with the highest deposition of pollutants from the atmosphere. Nevertheless, a major gap is the temporal characterization of the accumulation rate of magnetic particles in ecological indicators, which is critical to understand if the bioaccumulation process is linear or if saturation occurs. To overcome this problem, Parmotrema perlatum lichens were magnetically and chemically studied in a pollution gradient over space and time. Lichen transplants were exposed over 18 weeks to a high-traffic road. Results show that magnetic properties and element composition reflected both distance from the road (nonlinear decrease of up to 100 m from source) and exposure time (increasingly linearly over the entire study period with eightfold increments), showing that up to 18 weeks, the accumulation rate remained constant over time, with no saturation occurring. Chemical analysis showed a strong linear relationship between the accumulation of zinc (Zn), antimony (Sb), manganese (Mn), copper (Cu) chromium (Cr) and magnetic susceptibility. Magnetization acquisition curves reveal a time-dependent low-coercivity component, interpreted as mainly related to nonexhaust, mostly brake abrasion particle emissions. It is concluded that the magnetic properties of lichen transplants can be used in urban environments to characterize the spatial and temporal patterns of the deposition of pollution metallic particles from the atmosphere. [ABSTRACT FROM AUTHOR]

Middle and Late Holocene sediments have not been extensively sampled in Lake Tanganyika, and much remains unknown about the response of the Rift Valley's largest lake to major environmental shifts during the Holocene, including the termination of the African Humid Period (AHP). Here, we present an integrated study (sedimentology, mineralogy, and geochemistry) of a radiocarbon-dated sediment core from the Kavala Island Ridge (KIR) that reveals paleoenvironmental variability in Lake Tanganyika since the Middle Holocene with decadal to centennial resolution. Massive blue-gray sandy silts represent sediments deposited during the terminal AHP (~5880–4640 cal yr BP), with detrital particle size, carbon concentrations, light stable isotopes, and mineralogy suggesting an influx of river-borne soil organic matter and weathered clay minerals to the lake at that time. Enhanced by the AHP's warm and wet conditions, chemical weathering and erosion of Lake Tanganyika's watershed appears to have promoted considerable nutrient recharge to the lake system. Following a relatively gradual termination of the AHP over the period from ~4640 cal yr BP to ~3680 cal yr BP, laminated and organic carbon-rich sediments began accumulating on the KIR. δ15Nbulk, C/N, and hydrogen index data suggest high relative primary production from a mix of algae and cyanobacteria, most likely in response to nutrient availability in the water column under a cooler and seasonally dry climate from ~3680 to 1100 cal yr BP. Sediments deposited during the Common Era show considerable variability in magnetic susceptibility, total organic carbon content, carbon isotopes, and C/N, consistent with dynamic hydroclimate conditions that affected the depositional patterns, including substantial changes around the Medieval Climate Anomaly and Little Ice Age. Data from this study highlight the importance of sedimentary records to constrain boundary conditions in hydroclimate and nutrient flux that can inform long-term ecosystem response in Lake Tanganyika. [ABSTRACT FROM AUTHOR]

The Qilian Orogenic belt is one of the typical orogenic belts globally and a natural laboratory for studying plate tectonics. Many researchers have studied the ophiolite and high pressure and ultra-high pressure metamorphic rocks in the Qilian orogen and obtained valuable achievements. However, a hot debate exists on the basement property, the distribution of ophiolite, and the boundaries of tectonic units. Large-scale high-precision aeromagnetic surveys have recently been conducted in the Qilian Orogenic belt and adjacent areas. In this study, we are trying to analysis the tectonic framework of the Qilian Orogen using 1:500, 000 aeromagnetic data. The results provide geophysical perspectives for studying the structural framework and deformation of this area. According to the aeromagnetic ΔT anomaly map, the central and Southern Qilian have the same magnetic anomaly feature that noticeably differs from the North Qilian Orogenic belt and the Qaidam Block. This result indicates that the central and Southern Qilian have a unified magnetic basement and differ from the North Qilian orogenic belt and Qaidam Block. The map shows the distribution of ophiolite in the North Qilian orogenic belt. Linear magnetic anomalies represent the ophiolites because the mafic–ultramafic rocks usually have high magnetic susceptibility. The ophiolite belts are continuously distributed in the western part of North Qilian orogenic belt and have a large scale. However, the scale of the ophiolite belt and the outcropping of mafic–ultramafic rocks reduces when they pass through Qilian County to the east. The results indicate differences in the evolution process between the eastern and western parts of North Qilian, with Qilian County as the transition zone. This study also systematically defines the geophysical boundaries of the Qaidam Block, Qilian Block, North Qilian Orogenic belt, and Alxa block. It is proposed that the sinistral displacement of the Altun Fault is adjusted and absorbed by the series of NE-trending faults in the Qilian orogen and merge into the Longshoushan–Gushi Fault. The extension of the North Qilian Orogenic belt is strengthened by the neotectonics movement along the shearing direction, which separated the North Qilian Orogenic belt into several segments and formed a series of northeast-trending faults. [ABSTRACT FROM AUTHOR]

A new complex of copper(II) with methyl-5-(trifluoromethyl)pyrazol-3-yl-ketazine (H2L) was synthesized with the composition [Cu2L2]∙C2H5OH (1). Recrystallization of the sample from DMSO yielded a single crystal of the composition [Cu2L2((CH3)2SO)] (2). The coordination compounds were studied by single-crystal X-ray diffraction analysis, IR spectroscopy, and static magnetic susceptibility method. The data obtained indicate that the polydentate ligand is coordinated by both acyclic nitrogen and heterocyclic nitrogen atoms. The cytotoxic activity of the ligand and complex 1 was investigated on human cell lines MCF7 (breast adenocarcinoma), Hep2 (laryngeal carcinoma), A549 (lung carcinoma), HepG2 (hepatocellular carcinoma), and MRC5 (non-tumor lung fibroblasts). The complex was shown to have a pronounced dose-dependent cytotoxicity towards these cell lines with LC50 values in the range of 0.18–4.03 μM. [ABSTRACT FROM AUTHOR]

Physiotherapy plays a crucial role in the rehabilitation of damaged or defective organs due to injuries or illnesses, often requiring long-term supervision by a physiotherapist in clinical settings or at home. AI-based support systems have been developed to enhance the precision and effectiveness of physiotherapy, particularly during the COVID-19 pandemic. These systems, which include game-based or tele-rehabilitation monitoring using camera-based optical systems like Vicon and Microsoft Kinect, face challenges such as privacy concerns, occlusion, and sensitivity to environmental light. Non-optical sensor alternatives, such as Inertial Movement Units (IMUs), Wi-Fi, ultrasound sensors, and ultrawide band (UWB) radar, have emerged to address these issues. Although IMUs are portable and cost-effective, they suffer from disadvantages like drift over time, limited range, and susceptibility to magnetic interference. In this study, a single UWB radar was utilized to recognize five therapeutic exercises related to the upper limb, performed by 34 male volunteers in a real environment. A novel feature fusion approach was developed to extract distinguishing features for these exercises. Various machine learning methods were applied, with the EnsembleRRGraBoost ensemble method achieving the highest recognition accuracy of 99.45%. The performance of the EnsembleRRGraBoost model was further validated using five-fold cross-validation, maintaining its high accuracy. [ABSTRACT FROM AUTHOR]

The total content, forms, and mineralogy of iron compounds in soils of forest-steppe, steppe, and semidesert zones of a large territory from the central chernozem regions to the Caspian lowland and from the Southern Urals to the Kerch Strait are studied. The study covers Chernozems (n = 40), Kastanozems (n = 15), Solonetzes (n = 7), and Calcisols (n = 7). Our results demonstrate the specific features in the distribution of total iron content, mass balance (τFe, Zr), forms of iron compounds, magnetic susceptibility (χ), and mineralogy in soil profiles. The distribution of τFe, Zr in the studied soils reflects the processes and conditions of soil formation, as well as specific lithological features. For a more comprehensive understanding of the transformation of iron compounds in steppe soils, particle-size fractions (<2, 2–5, 5–10, and 10–50 μm) have been analyzed by Mössbauer spectroscopy and magnetic susceptibility methods for Luvic Chernozem, Haplic Kastanozem, Haplic Kastanozem (Endosalic, Cambic), and Luvic Calcisol (Endosalic). In the clay fraction, a large share of Fe3+ is contained in highly dispersed oxides and hydroxides in a superparamagnetic state. In the humus-accumulative horizons of steppe soils, a decrease in the Fe2+ fraction in aluminosilicates caused by weathering is recorded. The observed correlation of the goethite/(hematite + goethite) ratio in humus-accumulative soil horizons with climatic parameters suggests the possibility to apply it for future paleoclimatic reconstructions. Mössbauer spectroscopy shows a significant increase in the content of nonsilicate iron in the humus-accumulative horizons of steppe soils as compared with the soil-forming material, which is an important confirmation for the formation of iron oxides during pedogenesis. A comparison of the methods for assaying nonsilicate iron in soils (Mössbauer spectroscopy and Mehra–Jackson extraction) demonstrates considerable differences in the results, suggesting that the chemical technique underestimates the amount of free iron forms. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) around metal implants has been challenging due to magnetic susceptibility differences between metal implants and adjacent tissues, resulting in image signal loss, geometric distortion, and loss of fat suppression. These artifacts can compromise the diagnostic accuracy and the evaluation of surrounding anatomical structures. As the prevalence of total joint replacements continues to increase in our aging society, there is a need for proper radiological assessment of tissues around metal implants to aid clinical decision-making in the management of post-operative complaints and complications. Various techniques for reducing metal artifacts in musculoskeletal imaging have been explored in recent years. One approach focuses on improving hardware components. High-density multi-channel radiofrequency (RF) coils, parallel imaging techniques, and gradient warping correction enable signal enhancement, image acquisition acceleration, and geometric distortion minimization. In addition, the use of susceptibility-matched implants and low-field MRI helps to reduce magnetic susceptibility differences. The second approach focuses on metal artifact reduction sequences such as view-angle tilting (VAT) and slice-encoding for metal artifact correction (SEMAC). Iterative reconstruction algorithms, deep learning approaches, and post-processing techniques are used to estimate and correct artifact-related errors in reconstructed images. This article reviews recent developments in clinically applicable metal artifact reduction techniques as well as advances in MR hardware. The review provides a better understanding of the basic principles and techniques, as well as an awareness of their limitations, allowing for a more reasoned application of these methods in clinical settings. [ABSTRACT FROM AUTHOR]

Three new palladium(II)-iminophosphine complexes, [Pd(L1)(Cl)2] C1, [Pd(L2)(Cl)2] C2 and [Pd(L3)(Cl)2] C3 have been synthesized and successfully characterized by using 1H-NMR, 13C-NMR, 31P-NMR, UV–Vis, FT-IR and magnetic susceptibility techniques. Catalytic activities of complexes towards Suzuki–Miyaura C–C coupling reactions between phenylboronic acid and several aryl halides were investigated under several reaction conditions (solvent, temperature, base, reaction time, and type of substrate). Under optimum conditions, achieving high yields of up to 99% was possible. When 1-bromo-4-nitrobenzene was used for complex C1, bromobenzene for complex C2, and bromobenzene for complex C3, product yields of 99, 99, and 98% were achieved, respectively. Three new palladium complexes bearing iminophosphine ligands was synthesized and successfully characterized. Catalytic activities of the synthesized complexes were investigated on Suzuki–Myaura type coupling reaction between phenylboronic acid and several aryl halides. All complexes exhibited good catalytic activities on C–C coupling reactions up to 99% product formations under mild conditions. [ABSTRACT FROM AUTHOR]

The methods and result of scientific studies are often difficult to understand for non-specialists due to their esoteric nature. Such lack of understanding means that such work is removed from our normal life experience, and thus, the applicability, interest and use of such work can be minimal. The communication of geoscience finds a natural conduit through geoheritage. A good example of an inaccessible technique far removed from everyday experience is anisotropy of magnetic susceptibility (AMS), an extremely useful geoscience technique with many applications, including finding strain and flow directions in rocks. We explored here how to make "AMS" understandable, using three different volcanic sites where the flow of molten rock is an important aspect, each situated in different types of geoheritage visitation context (wild trekkers, beach visitors, and walkers). The method we developed and tested follows the production of simple and adapted explanations, and is coupled with geoheritage inventorying and communication. We utilized the tangible geological features of outcrops, as well as intangible elements such as rock magnetic data, and conducted a geoheritage inventory using the modified geosite assessment model (M-GAM) to create narratives for popular comprehension. The M-GAM analysis has identified the geosites of the San Bartolo lava flow of the Stromboli volcano for the communication of AMS. Later, a simple and comprehensible definition of AMS and thus of the flow processes was created using a step-by-step process. This method could be useful for scientific studies to allow them to reach out to a wider public, using their input in the simple explanation stage to con-construct a narrative. This would provide a way for science to be more widely appreciated, useful and applicable. [ABSTRACT FROM AUTHOR]

The change in vegetation at the margins of the East Asian summer monsoon (EASM) during the Miocene Climatic Optimum (MCO) remains poorly understood. Here, we present a high‐resolution terrestrial sequence, paleomagnetically dated to 18.2–13.5 Ma, from the Tongxin Basin of midwestern China. Our multi‐indicator analysis, encompassing pollen, δ13CTOC, δ18Ocarb‐δ13Ccarb, and magnetic susceptibility, reveals that the regional vegetation and climate had two distinct stages during the MCO, manifesting as stable arid steppe from 17.0 to 16.0 Ma, and woodland steppe with six forested environments from 16.0 to 14.0 Ma. Together with other adjacent records, this supports the EASM as the main control on terrestrial vegetation. Further comparisons of marine‐terrestrial data and time series analysis suggest that in the late MCO, the oceanic carbon reservoir (OCR) experienced strong perturbations (mainly Cmax events) accompanied by multiple oscillations. The instability signals likely impacted and were amplified as rapid shifts in forest‐steppe environments at the monsoon margins via EASM. Our study highlights the regulation of inland ecologically vulnerable areas by low‐latitude forcing in a greenhouse world. Plain Language Summary: Exploring the response of vegetation to the Miocene Climatic Optimum (MCO, ∼17.0–14.0 Ma) can serve as an analogy for studies of ecological impacts under future global warming. Here, we perform magnetostratigraphic dating and past vegetation‐climate reconstruction in high‐resolution terrestrial sediments in the Tongxin Basin of Midwest China, a region sensitive to the East Asian summer monsoon (EASM). The records of several indicators, including pollen, δ13CTOC, δ18Ocarb‐δ13Ccarb and magnetic susceptibility, indicate that the regional climate and vegetation changed in two major stages across the warm MCO. Between 16.0 and 17.0 Ma, the regional vegetation was predominantly stable arid steppe, followed by at least six rapid oscillations between arid steppe and forest environments between 14.0 and 16.0 Ma. Further analyses show that EASM intensity dominates regional changes in vegetation, and its changing pattern is quasi‐similar to global oceanic δ13C changes reflecting the state of oceanic carbon reservoir (OCR). Multiple rapid shifts in the forest‐steppe landscape during the late MCO are closely related to fluctuations in the EASM system, which are modulated by strong oscillations in the OCR. Our study reveals the non‐negligible role of the low‐latitude marine carbon cycle in forcing inland ecologically vulnerable areas during global climatic warming. Key Points: The age of the Miocene Tongxin Fauna is constrained to 18.0–14.0 Ma by magnetostratigraphy and biostratigraphyThe stability of the regional climate‐vegetation system underwent a two‐stage evolutionary pattern during the Miocene Climatic Optimum (MCO)Regional vegetation oscillations are likely to respond to ocean carbon reservoir perturbation in the late MCO [ABSTRACT FROM AUTHOR]

Quantitative Susceptibility Mapping (QSM) is an advanced magnetic resonance imaging (MRI) technique to quantify the magnetic susceptibility of the tissue under investigation. Deep learning methods have shown promising results in deconvolving the susceptibility distribution from the measured local field obtained from the MR phase. Although existing deep learning based QSM methods can produce high‐quality reconstruction, they are highly biased toward training data distribution with less scope for generalizability. This work proposes a hybrid two‐step reconstruction approach to improve deep learning based QSM reconstruction. The susceptibility map prediction obtained from the deep learning methods has been refined in the framework developed in this work to ensure consistency with the measured local field. The developed method was validated on existing deep learning and model‐based deep learning methods for susceptibility mapping of the brain. The developed method resulted in improved reconstruction for MRI volumes obtained with different acquisition settings, including deep learning models trained on constrained (limited) data settings. [ABSTRACT FROM AUTHOR]

Geoforensic techniques are being deployed in searches for hidden objects to counteract the shortcomings of conventional blunderbuss methods. Processing of crime scenes during searches for clandestine graves and buried objects is often destructive. Manual excavation and other invasive methods are restricted in many contemporary situations, and the location of a body is essential for forensic investigations. Geoforensics and geophysical surveys are important tools for assisting law enforcement agencies in locating crime scenes, clandestine graves, drugs, artifacts, hazardous waste, and illegal weapons and ammunitions stored underground in preparation for terrorist attacks. Geoscience search techniques such as the geoforensic search strategy are among many models used to help find mass graves, locate missing persons, and verify information acquired from incomplete intelligence. Trace amounts of soils, sediments, and other geological materials can provide geolocations and aid in the development of a primary search area. Forensic geoscience techniques and equipment such as metal detectors, magnetic surveys, electromagnetic conductivity surveys, ground penetrating radar surveys, augering (probing), detector dogs surveys, and gravity and seismic fluctuation monitoring are discussed in this paper. In addition to the location of potential graves and ambush sites, the soil beneath the decomposing cadavers can be used to predict the postmortem interval for the deceased. Soil information and geo-mapping data can provide productive intelligence for military and national security agencies. Antiquities crimes and crimes involving gemstones in which the evidence passes through many hands can be traced back to the place of origin by checking for their geo-morphology. Serious crimes, including murder, genocide, and terrorism, can be prevented by the use of operational and decisive geoforensic techniques. This paper highlights the multidisciplinary information exchange that occurs between forensic burial science, forensic geology, and trace evidence in criminal investigations. The paper also focuses on geoforensic approaches to clandestine grave searching, underwater investigations, forensic engineering fallacies, military intelligence, ambush detection, and weapons mining.

A simplified model of anisotropic magnetic susceptibility in the Meissner–London vortex-free state of cuboidal superconducting samples is presented. Using this model, precision measurements of the magnetic response in three perpendicular directions of a magnetic field with respect to primary crystal axes can be used to extract the components of the London penetration depth, thus enabling the evaluation of the general superfluid density tensor, which is needed in the analysis of the superconducting gap structure. [ABSTRACT FROM AUTHOR]

Purpose: To introduce quantitative rapid gradient‐echo (QRAGE), a novel approach for the simultaneous mapping of multiple quantitative MRI parameters, including water content, T1, T2*, and magnetic susceptibility at ultrahigh field strength. Methods: QRAGE leverages a newly developed multi‐echo MPnRAGE sequence, facilitating the acquisition of 171 distinct contrast images across a range of TI and TE points. To maintain a short acquisition time, we introduce MIRAGE2, a novel model‐based reconstruction method that exploits prior knowledge of temporal signal evolution, represented as damped complex exponentials. MIRAGE2 minimizes local Block‐Hankel and Casorati matrices. Parameter maps are derived from the reconstructed contrast images through postprocessing steps. We validate QRAGE through extensive simulations, phantom studies, and in vivo experiments, demonstrating its capability for high‐precision imaging. Results: In vivo brain measurements show the promising performance of QRAGE, with test–retest SDs and deviations from reference methods of < 0.8% for water content, < 17 ms for T1, and < 0.7 ms for T2*. QRAGE achieves whole‐brain coverage at a 1‐mm isotropic resolution in just 7 min and 15 s, comparable to the acquisition time of an MP2RAGE scan. In addition, QRAGE generates a contrast image akin to the UNI image produced by MP2RAGE. Conclusion: QRAGE is a new, successful approach for simultaneously mapping multiple MR parameters at ultrahigh field. [ABSTRACT FROM AUTHOR]

Purpose: The structural similarity index measure (SSIM) has become a popular quality metric to evaluate QSM in a way that is closer to human perception than RMS error (RMSE). However, SSIM may overpenalize errors in diamagnetic tissues and underpenalize them in paramagnetic tissues, resulting in biasing. In addition, extreme artifacts may compress the dynamic range, resulting in unrealistically high SSIM scores (hacking). To overcome biasing and hacking, we propose XSIM: SSIM implemented in the native QSM range, and with internal parameters optimized for QSM. Methods: We used forward simulations from a COSMOS ground‐truth brain susceptibility map included in the 2016 QSM Reconstruction Challenge to investigate the effect of QSM reconstruction errors on the SSIM, XSIM, and RMSE metrics. We also used these metrics to optimize QSM reconstructions of the in vivo challenge data set. We repeated this experiment with the QSM abdominal phantom. To validate the use of XSIM instead of SSIM for QSM quality assessment across a range of different reconstruction techniques/algorithms, we analyzed the reconstructions submitted to the 2019 QSM Reconstruction Challenge 2.0. Results: Our experiments confirmed the biasing and hacking effects on the SSIM metric applied to QSM. The XSIM metric was robust to those effects, penalizing the presence of streaking artifacts and reconstruction errors. Using XSIM to optimize QSM reconstruction regularization weights returned less overregularization than SSIM and RMSE. Conclusion: XSIM is recommended over traditional SSIM to evaluate QSM reconstructions against a known ground truth, as it avoids biasing and hacking effects and provides a larger dynamic range of scores. [ABSTRACT FROM AUTHOR]

In the present study, conformations and aromaticity of seventeen [13], [23] and [33] double-stranded cyclophanes composed of three benzene moieties were investigated at B3LYP level of density functional theory. The stability of these conformers is different depending on the type of cycloalkane-like cycles formed by (CH2) n bridges and the peripheral benzene rings, and also the curvature of the latter. In [13] cyclophane, this leads to only one conformer containing puckered cyclobutane-like cycle, at an angle of about 37◦. In comparison, in cyclophanes [23] and [33], the corresponding cycles are cyclohexane-like and cyclooctane-like, respectively. While conformer 2a having TB-like cycles is the most stable member of the [23] family, of eight ground-state conformers obtained for [33], 3a with two Chair-Chair-like and one Twist-Chair-like cycles is the most stable one, and 3h with three Twist-Boat-like cycles being 6.5 kcal higher in energy than the former is the least stable member of series. In addition to the conformational analysis, the aromaticity of the series has been assessed using different indexes, including magnetic criteria nucleus-independent chemical shifts (NICS-based) at the cage and at the ring centers, HNMR chemical shift, Magnetic Susceptibility, HOMA and relative energy (RE). [ABSTRACT FROM AUTHOR]

We synthesized La2NiO4 nanostructures using the cationic surfactant-based reverse micellar route and reported on the effect of the size and shape of the La2NiO4 nanostructures on their magnetic and photoelectrochemical properties. We satisfactorily refined the powder X-ray diffraction data in the tetragonal space group, I4/mmm. Magnetic susceptibility measurements were performed on all samples within the range of 5–300 K. The Curie–Weiss law determines the magnetic susceptibility of bulk La2NiO4, and a negative value for the Weiss temperature indicates antiferromagnetic exchange. The field-dependent magnetization curves of bulk La2NiO4 suggest a canted antiferromagnetic behaviour. The Mott–Schottky plot demonstrates that La2NiO4 is a p-type semiconducting material with holes as the primary charge carriers. Chronoamperometric measurements for these nanomaterials demonstrate excellent photostability of photocurrent. [ABSTRACT FROM AUTHOR]

Magnetic studies of loess–paleosol sequences have shown that the magnetic properties of loess and its parent material are sensitive to weathering degree. However, the relationship between magnetic properties and weathering processes in red soils of southern China remains unclear due to the diversity of parent rocks and the influence of climate. This study focused on red soils developed on weakly magnetic sandstone, in tropical and subtropical regions of Yunnan, China. The principal element content, magnetic susceptibility, temperature-dependent susceptibility curve (χ–T curve, where χ represents the magnetic susceptibility at the corresponding temperature during the heating and cooling process of the sample, and T represents the temperature during the heating and cooling process.), hysteresis loop and Isothermal Remanent Magnetization (IRM) of the samples were determined, the weathering characteristics and magnetic properties of profile samples were analyzed, and their relationship was examined, as well as the impact of climate change on fine-grained ferrimagnetic minerals and magnetic properties. The results revealed that red soils developed on weakly magnetic sandstone exhibited significant correlations between three magnetic indices, low-frequency magnetic susceptibility (χlf), frequency-dependent susceptibility (χfd), (χpost-pre + χd)/χpara, and the silica-sesquioxide ratio (SAF), indicating that these indices can be used to assess soil weathering. Additionally, this study proposed a new index based on the 1 < Log10Bh < 1.5 mT component obtained from decomposition of the IRM curve, which can also be used to assess soil weathering. The enhancement of magnetic properties in red soils along a single profile was found to be related to the increase in the content of fine-grained ferrimagnetic com-ponents controlled by weathering. Comparing the two climatic regions, it was found that in Yunnan, China, as the climate changes from subtropical humid to tropical humid, the weathering of the red soil profiles becomes stronger, and the fine-grained ferrimagnetic components increase, indirectly enhancing the magnetic properties of red soils. [ABSTRACT FROM AUTHOR]

In mineral exploration, the ores with different magnetic susceptibility can be well delineated by physical property inversion of magnetic data. However, further wide applications of the magnetic inversion method have been seriously restricted by the existence of strong remanence and the computation of large-scale datasets. To solve these two problems, this study innovatively presents an efficient magnetic inversion algorithm in the presence of strong remanence. The weighted data misfit term and regularization term were used to establish the objective function. The detailed related formulas were derived and presented. For numerical computation, the Taylor series approximation was introduced in the objective function to linearize the relationship between the transformed magnetic data and magnetic susceptibility. The objective function was converted to a general Tikhonov form by several matrix transformations. To realize computational efficiency, a fast randomized algorithm was utilized to efficiently solve the Tikhonov problem and to efficiently determine the suitable regularization parameter along with the generalized cross-validation (GCV) method. Comparative tests on synthetic example show the effectiveness and efficiency of the proposed algorithm. The proposed efficient algorithm is successfully applied to two sets of real magnetic data, and the inversion results are verified. [ABSTRACT FROM AUTHOR]

In this study, we present a novel method for measuring the magnetic susceptibility of liquids using a Mach–Zehnder interferometer. The proposed technique employs a ring magnet to deform the liquid, while a laser beam passes through the liquid to measure the resulting interference pattern. The deformation of the liquid, caused by the known magnetic field of the ring magnet, is used to calculate the magnetic susceptibility. We provide a comprehensive theoretical framework, including the relevant equations and models, for analyzing the data obtained using this method. We compare the Mach–Zehnder interferometer method with other established techniques, highlighting its advantages and disadvantages. Our findings indicate that the Mach–Zehnder interferometer technique offers high accuracy, sensitivity, and potential applications in characterizing the magnetic properties of various liquid systems. [ABSTRACT FROM AUTHOR]

Magnetic powder is regarded as an effective and economical tracer for estimating soil erosion. However, the principle and application for using magnetic powder to estimate soil erosion are still not fully developed. In this study, magnetic powders with mean diameters of both 30 and 1 μm were mixed into three soils at different mass proportion. The relationship between magnetic susceptibility and the mass proportion of the introduced magnetic powder in the tagged soil, and the binding ability of magnetic powder to soil particles after both dry and wet sieving were investigated. The accuracy of tracking soil loss by using magnetic powder as a tracer was assessed. The results showed that there was a significant linear relationship between the magnetic susceptibility and the mass proportion of the introduced magnetic powder in the tagged soil. The relationship between the amount of soil captured by a magnet and the mass proportion of magnetic powder in the tagged soil indicated that soils were readily magnetized by magnetic powder, especially fine fractions. The magnetic susceptibility of magnetic powder in different sizes of soil aggregates was variable. A majority of magnetic powder of both 30 and 1 μm diameters was strongly bound with fine particles

Worldwide, Quaternary loess-paleosol sequences archive terrestrial paleoenvironmental information. The Palouse loess in the northwestern USA is one such deposit representing at least a million years of sediment accumulation. Loess paleosol sequences are often studied via the magnetic susceptibility of sediments and the changes in susceptibility with depth. However, since variations in magnetic susceptibility can have different underlying causes, the interpretation of the magnetic susceptibility of loess depends on factors specific to each major loess region. We measured the magnetic susceptibility of sediments along depth profiles in a well-studied exposure of the Palouse loess in eastern Washington, USA (the "CLY-2 site," 46.3131° N, 118.4874° W, WGS84). Our measurements show that the magnetic susceptibility of sediments in the Palouse loess varies systematically and predictably with depth and can be correlated with other magnetic susceptibility profiles at the outcrop scale and at the regional scale. We also measured changes in grain size, elemental abundance, mineralogy, and other magnetic properties to determine the most likely cause of the magnetic susceptibility signal. Based on these results, variations in magnetic susceptibility in the Palouse are likely driven mostly by changes in coarse sediment supply and accumulation of tephra rather than changes in weathering. Magnetic susceptibility is useful as an inexpensive, non-destructive tool for stratigraphic correlation of Quaternary loess deposits in the Palouse, especially in combination with paleosol stratigraphic markers and known tephra deposits. [ABSTRACT FROM AUTHOR]

Background and purpose Methods Results Conclusions Susceptibility estimates derived from quantitative susceptibility mapping (QSM) images for the cerebral cortex and major subcortical structures are variably reported in brain magnetic resonance imaging (MRI) studies, as average of all (μall${{{{\mu}}}_{{\mathrm{all}}}}$), absolute (μabs${{{{\mu}}}_{{\mathrm{abs}}}}$), or positive‐ (μp${{{{\mu}}}_{\mathrm{p}}}$) and negative‐only (μn${{{{\mu}}}_{\mathrm{n}}}$) susceptibility values using a region of interest (ROI) approach.This pilot study presents a reliability analysis of currently used ROI‐QSM metrics and an alternative ROI‐based approach to obtain voxel‐weighted ROI‐QSM metrics (μwp${{{{\mu}}}_{{\mathrm{wp}}}}$ and μwn${{{{\mu}}}_{{\mathrm{wn}}}}$).Ten healthy subjects underwent repeated (test‐retest) 3‐dimensional multi‐echo gradient‐echo (3DMEGE) 3 Tesla MRI measurements. Complex‐valued 3DMEGE images were acquired and reconstructed with slice thicknesses of 1 and 2 mm (3DMEGE1, 3DMEGE2) along with 3DT1‐weighted isometric (voxel 1 mm3) images for independent registration and ROI segmentation.Agreement, consistency, and reproducibility of ROI‐QSM metrics were assessed through Bland‐Altman analysis, intraclass correlation coefficient, and interscan and intersubject coefficient of variation (CoV).All ROI‐QSM metrics exhibited good to excellent consistency and test‐retest agreement with no proportional bias. Interscan CoV was higher for μall${{{{\mu}}}_{{\mathrm{all}}}}$ in comparison to the other metrics where it was below 15%, in both 3DMEGE1 and 3DMEGE2 datasets. Intersubject CoV for μall${{{{\mu}}}_{{\mathrm{all}}}}$ and μabs${{{{\mu}}}_{{\mathrm{abs}}}}$ exceeded 50% in all ROIs.Among the evaluated ROI‐QSM metrics, μall${{{{\mu}}}_{{\mathrm{all}}}}$ and μabs${{{{\mu}}}_{{\mathrm{abs}}}}$ estimates were less reliable, whereas separating positive and negative values (using μp,μn,μwp,μwn${{{{\mu}}}_{\mathrm{p}}},\ {{{{\mu}}}_{\mathrm{n}}},\ {{{{\mu}}}_{{\mathrm{wp}}}},\ {{{{\mu}}}_{{\mathrm{wn}}}}$) improved the reproducibility within, and the comparability between, subjects, even when reducing the slice thickness. These preliminary findings may offer valuable insights toward standardizing ROI‐QSM metrics across different patient cohorts and imaging settings in future clinical MRI studies. [ABSTRACT FROM AUTHOR]

An asymmetrical dysprosium trimer with a molecular formula of [Dy3(hq)7(hqH)(NO3)2(H2O)] was obtained through a reflux reaction employing as starting material Dy(NO3)3·nH2O and 8-quinolinoline as ligand. Magnetic susceptibility investigations show the system to be an SMM, which was corroborated by sub-Kelvin μSQUID studies. Upon cooling, the magnetic susceptibility also exhibits a decrease in the χMT product, which was confirmed to be due to intramolecular antiferromagnetic interactions. μSQUID measurements, moreover, reveal a marked magnetic behaviour in the angular dependence of the hysteresis loops. The latter is a direct consequence of the non-colinear spin arrangement of the anisotropy axes of each Dy(III) ion in [Dy3(hq)7(hqH)(NO3)2(H2O)] and the interaction between the ions, as also evidenced by CASSCF calculations. Our results evidence the effect of spin canting along with the intramolecular interactions, which can induce non-trivial magnetic behaviour in SMMs. [ABSTRACT FROM AUTHOR]

Dykes are one of the primary subvolcanic bodies that transport magma from the shallow magma chamber or from the deep-seated magma reservoir. The mechanism of magma transport and emplacement in dyke swarms can contribute precious details on source and how magma has associated with crustal rocks. Here we are presenting the results obtained from the Anisotropy of magnetic susceptibility (AMS) on their mode of emplacement and to understand magma flow direction. AMS and rock magnetic studies were performed on 33 dykes located on the West coast of Maharashtra, (India) to determine the magma flow direction using magnetic fabric. Thermomagnetic curves and hysteresis loop measurement indicates that titanomagnetite of associated pseudo-single-domain/multi-domain grain sizes are responsible for the magnetic fabrics. Based on the clustering of the principal AMS axes, three types of AMS fabrics were recognized, (i) Normal fabric, interpreted as due to magma flow characterised by clustering of K1–K2 axes on the dyke plane and K3 axes are nearly perpendicular to it, (ii) Inverse fabric with K2–K3 plane parallel to the dyke plane and K3 is perpendicular to it and (iii) Intermediate fabric, with K1–K3 axes clustering close to dyke plane. The inclination of the K1 axis (IK1) of Normal fabric is the most important to determine the flow of magma for the studied dyke swarm. The IK1 of the studied dykes were fed dominantly by horizontal (IK1 < 30°), inclined (30° < IK1 < 60°) up to vertical fluxes (IK1 > 60°). These results suggest that the dykes may be closer to the magma source and horizontal magma flow inferred from the dykes reveals source is located further away. The present AMS study along with geophysical, geochemical and petrological study supports the evidence of feeder fed mechanism. [ABSTRACT FROM AUTHOR]

Magnetism in Croatian caves has been significantly underexplored, despite the well-documented preservation of cave sediments. This study investigates whether magnetic susceptibility can be effectively recorded in Croatian caves and, if so, whether there are differences between in situ and laboratory measurements, as well as the extent of these differences. The focus is on two prominent sites within the Velebit Mountain range of the Dinaric Karst: the deep Slovačka Cave and the extensive Crnopac Cave System (ex. Kita Gaćešina Cave). Magnetic susceptibility was measured in soft sediments using the Kappameter KM-7 for in situ assessments and the Bartington MS2B System for laboratory analyses. The comparison of the two devices aimed to evaluate the feasibility of detecting magnetic susceptibility variations within carbonate sediments. Sampling locations were selected based on preliminary assessments of magnetic susceptibility variations and accessibility for sampling. Characteristic samples from each profile underwent X-ray powder diffraction analysis. Results revealed significant variations in magnetic susceptibility across each profile under both in situ and laboratory conditions. In situ measurements ranged from −45 × 10−5 SI to 120 × 10−5 SI, while laboratory measurements ranged from 4.00 × 10−5 SI to 99.40 × 10−5 SI. The portable Kappameter KM-7 provided satisfactory results for preliminary investigations, while the Bartington MS2B System demonstrated high precision in analyzing these variations in detail. These findings support the potential for further investigations into magnetic susceptibility in karst cave environments, with an emphasis on understanding depositional history and the timeline of climate and tectonic changes. [ABSTRACT FROM AUTHOR]

The equilibrium geometry, tensors of diamagnetic, paramagnetic and magnetic susceptibility of (TiO2)n clusters (n = 1–4, 10–16) and supramolecular complexes [(TiO2)10(H2O)m] (m = 1–12) are calculated using the density functional theory in the M06/6-31G(d,p) approximation. A conclusion is reached on the predominance of the paramagnetic contribution and the strong effect the size and hydration of clusters have on the isotropic magnetic susceptibility. Correlations are established and regression equations are proposed for the isotropic magnetic susceptibility and the numbers of electrons in clusters (TiO2)n and water molecules in complexes (TiO2)10(H2O)m. [ABSTRACT FROM AUTHOR]

Three samples of aqueous magnetic fluids based on magnetite particles stabilized with double layers of surfactants have been synthesized. The samples have been stabilized with lauric and oleic acids, as well as their salts, taken in three different combinations. The viscosity of the synthesized samples has been measured as depending on the concentration, temperature, and shear rate. With increasing temperature, the viscosity of a sample of the fluid stabilized with a double layer of lauric acid does not decrease relative to the viscosity of water, as has been previously observed for classical magnetic fluids, but rather increases. For a sample stabilized with two layers of lauric and oleic acids, the temperature dependence of the relative viscosity is nonmonotonic. The relative viscosity of a sample stabilized with a double layer of oleic acid is actually independent of temperature. To determine the concentrations of the samples, measurements of magnetization curves were carried out followed by their granulometric analysis. It has been found that the dispersity of the samples remains unchanged upon dilution. The initial magnetic susceptibility of the fluid samples has been shown to increase with concentration more slowly than it has been predicted by the modified effective field model. In contrast to the effective field model (and other ones), the coefficient at the quadratic term in the expansion of the initial susceptibility in terms of the Langevin susceptibility has turned out to be significantly lower than 1/3. Thus, new theories of dipole–dipole interparticle interaction must be developed to describe the properties of magnetic fluids stabilized with double layers of surfactants. [ABSTRACT FROM AUTHOR]

Zn‐substituted iron oxide nanoparticles of ≈5 nm in diameter are synthetized by a microwave‐assisted thermal decomposition method. The addition of ethylene glycol results in a size increase to 22 nm. Cationic disorder has been observed by electron energy loss spectroscopy–scanning transmission electron microscopy. Using Mössbauer spectrometry combined with Rietveld analysis, the complete cationic and vacancies repartition in the lattice is determined, as well as the canting of magnetic moments. This allows the magnetic moment to be calculated, in good agreement with that measured. The alternating current magnetic susceptibility is modeled by the Néel–Brown and the Coffey models, showing some discrepancy between these two approaches which is discussed. The largest particles show a complex morphology involving an oriented attachment mechanism of smaller units. Their cationic disorder and internal porosity have been evidenced and quantified, and the work shows that despite these defects they behave rather as magnetically blocked nanoparticles. [ABSTRACT FROM AUTHOR]

Some rock and soil samples exhibit significant loss of magnetic susceptibility (χ) with increasing applied field amplitude even at relatively low (10–100s of A/m) fields, a behavior which remains unexplained. Exceptionally strong negative field‐dependence of susceptibility (χHD) is present in sandstones and altered intermediate‐felsic igneous rocks in several cores from the northeastern Oklahoma subsurface. These same rocks also show elevated frequency‐dependence of susceptibility (χFD), with reasonable correlation of χHD to χFD, and frequency‐dependent χHD. Results from multiple characterization methods indicate that strongly negative χHD in these rocks is linked to a yet‐unidentified phase which begins the approach to magnetic saturation in low fields (<1 mT/800 A/m), shows elevated χFD to low temperatures, is unstable at high temperatures, possesses significant anisotropy of magnetic susceptibility, and becomes paramagnetic above ∼83°C. Clear associations with fluid alteration features indicate that this material may be highly relevant to rock alteration, diagenetic, and environmental studies. Plain Language Summary: Magnetic susceptibility is usually measured using weak magnetic fields, and in many geological materials the value depends on the strength of the field used. In the low‐field range, this usually results in slightly higher susceptibility values as field strength increases. In some rocks and soils, however, susceptibility decreases with increasing applied field, which has not been explained. The lowermost sandstones and uppermost igneous rocks in the northeastern Oklahoma subsurface have been found to provide prominent examples of this "negative field‐dependence" of susceptibility. When susceptibility of the same rocks is measured using an alternating‐current field, the results are also highly dependent on the frequency of that field. The strength of these behaviors is correlated, and both are found to be associated with a yet‐unidentified magnetization carrier with an apparent Curie temperature of ∼83°C. Through direct‐current measurements, it is apparent that the negative field‐dependence is due to this mineral approaching magnetic saturation at unusually low fields relative to most natural materials. The magnetic behavior is associated with other evidence of water‐rock interaction, which may prove to be a useful indicator of chemical conditions of alteration, diagenesis, and weathering. Key Points: Negative field‐dependence of magnetic susceptibility is poorly understood and occurs in rocks near the basement unconformity of NE OklahomaThis behavior is due to low‐field magnetic saturation of an unknown magnetic carrier with a magnetic ordering temperature near 80°CThe carrier is associated with frequency‐dependence of susceptibility and fluid alteration and may complicate environmental studies [ABSTRACT FROM AUTHOR]

The magnetic properties of Aurivillius-phase Bi7Fe3Ti3O21 (BFT) and Bi7−xGdxFe3Ti3O21, where x = 0.2, 0.4, and 0.6 (BGFT), were investigated. Ceramic material undoped (BGF) and doped with Gd3+ ions were prepared by conventional solid-state reaction. In order to confirm that the obtained materials belong to Aurivillius structures, XRD tests were performed. The XRD results confirmed that both the undoped and the gadolinium-doped materials belong to the Aurivillius phases. The qualitative chemical composition of the obtained materials was confirmed based on EDS tests. The temperature dependences of magnetization and magnetic susceptibility were examined for the ceramic material both undoped and doped with Gd3+ ions. The measurements were taken in the temperature range from T = 10 K to T = 300 K. Using Curie's law, the value of the Curie constant was determined, and on its basis, the number of iron ions that take part in magnetic processes was calculated. The value of Curie constant C = 0.266 K, while the concentration of iron ions Fe3+, which influence the magnetic properties of the material, is equal 3.7 mol% (for BFT). Hysteresis loop measurements were also performed at temperatures of T = 10 K, T = 77 K, and T = 300 K. The dependence of magnetization on the magnetic field was described by the Brillouin function, and on its basis, the concentration of Fe3+ ions, which are involved in magnetic properties, was also calculated (3.4 mol% for BFT). Tests showed that the material is characterized by magnetic properties at low temperatures. At room temperature (RT), it has paramagnetic properties. It was also found that Gd3+ ions improve the magnetic properties of tested material. [ABSTRACT FROM AUTHOR]

In this work, we study the magnetocaloric properties of half 5/2 and integer 3 mixed spin model on a square–hexagon «4-6» structures are studied by Monte Carlo simulations. The total magnetization and the magnetization of each sub-lattice of the mixed-spin lattice have been analyzed. The magnetic susceptibility, dM/dT and magnetic entropy changes are found. The magnetic hysteresis cycles under, with the temperatures, exchange interactions (S-S), (σ-σ) and (σ-S), and the crystal fields (Dσ and DS) has been discussed. [ABSTRACT FROM AUTHOR]

The in situ measurement of sediment transport in wave‐dominated environments presents significant challenges and currently often relies upon the use of fluorescent sediment tracers. However, this method is constrained by challenges in conducting unbiased and representative sampling, as well as facing overall logistical complexities and labour‐intensive procedures. Whilst other tracer techniques are available, such as using magnetic tracers, their performance in tracking sediment transport has not been quantified. The objective of this study is to assess the effectiveness of magnetic tracers in evaluating net transport rates and tracer dispersal patterns. Conducted in a controlled large wave flume, the experiments simultaneously employed fluorescent and magnetic tracers, allowing a comprehensive comparison of the tracers' dispersion patterns and the net transport rates. Results show that the dispersal of magnetic and fluorescent tracers displays a high degree of spatial coherence in both horizontal and vertical dimensions. Similarly, net transport rates are comparable (<16% difference), both showing net transport in the direction of the wave propagation (towards onshore) driven by non‐linear and streaming effects. Magnetic tracer recovery rate (49%) was lower than for fluorescent tracers (73%) and is attributed to the loss of magnetic ink from particles; an aspect of the magnetic technique that requires improvement. This study therefore indicates that the use of magnetic tracers to quantify sediment transport is an effective method with the advantages of being significantly less labour‐intensive than using the commonly applied fluorescent sediment tracer method. [ABSTRACT FROM AUTHOR]

SUMMARY: Magnetic susceptibility behaviour around the Verwey transition of magnetite (≈125 K) is known to be sensitive to stress, composition and oxidation. From the isotropic point (≈130 K) to room temperature, decreasing magnetic susceptibility indicates an increase in magnetocrystalline anisotropy. In this study, we present a model which numerically analyses low-temperature magnetic susceptibility curves (80–280 K) of an experimentally shocked (up to 30 GPa) and later heated (973 K) magnetite ore. To quantify variations of the transition shape caused by both shock and heating, the model statistically describes local variations in the Verwey transition temperature within bulk magnetite. For the description, Voigt profiles are used, which indicate variations between a Gaussian and a Lorentzian character. These changes are generally interpreted as variations in the degree of correlation between observed events, that is between local transition temperatures in the model. Shock pressures exceeding the Hugoniot elastic limit of magnetite ($ \ge $ 5 GPa) cause an increase in transition width and Verwey transition temperature, which is partially recovered by heat treatment. Above the Verwey transition temperature, susceptibility variations related to the magnetocrystalline anisotropy are described with an exponential approach. The room temperature magnetic susceptibility relative to the maximum near the isotropic point is reduced after shock, which is related to grain size reduction. Since significant oxidation and cation substitution can be excluded for the studied samples, variations are only attributed to changes in elastic strain associated with shock-induced deformation and annealing due to heat treatment. The shocked magnetite shows a high correlation between local transition temperatures which is reduced by heat treatment. The model allows a quantitative description of low-temperature magnetic susceptibility curves of experimentally shocked and subsequently heat-treated polycrystalline magnetite around the Verwey transition temperature. The curves are accurately reproduced within the experimental uncertainties. Further applications for analysing magnetite-bearing rocks seem possible if model parameters, such as for oxidation are included into the model. [ABSTRACT FROM AUTHOR]

We have prepared and investigated superconducting equimolar medium-entropy alloys of TiZrNb and TiZrNbHf. Their basic superconducting parameters, as the values of the critical temperature Tc, upper critical magnetic field Bc2 and the superconducting energy gap Δ have been studied with the use of magnetic susceptibility and point-contact Andreev reflection (PCAR) spectroscopy measurements. Although our samples have different critical temperatures, namely Tc ∼ 8.2 K for TiZrNb and Tc ∼ 6.3 K for TiZrNbHf, their zero-temperature critical magnetic field has the same value Bc2(0) = 12 T, from the vicinity of the Clogston limit. We have observed the presence of degraded phases on the surfaces of all the investigated samples using PCAR measurements. Still, we were able to show that the bulk phase in both systems exhibits BCS weakly coupled superconductivity with 2Δ(0)/kBTc ∼ 3.5. [ABSTRACT FROM AUTHOR]

Cerium doped Mn0.5Zn0.5Fe2O4 spinel nano-magnets were synthesized using sol–gel technique and characterized through x-ray diffraction (XRD), Fourier transform-infrared radiation (FT-IR), impedance analyzer, modulus spectroscopy, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and energy dispersive x-ray spectroscopy (EDX). The cations redistribution with Ce3+ substitution strongly affect the physical properties of the samples. Single phase spinel structure is identified for the synthesized samples and the crystal imperfection is found low. The lattice parameters reduce with Ce3+ concentration due to lanthanide contraction. The saturation magnetization of Mn0.5Zn0.5CexFe2−xO4 is found maximum for the x = 0 sample. The measured magnetic properties such as coercivity (Hc), retentivity (Mr) and saturation magnetization (Ms) decrease with increase in Ce3+ concentration. The synthesized samples show positive values of magnetic susceptibility which show anti-ferromagnetic/ferrimagnetic nature. The SEM images show increase in size of the grain with increasing sintering conditions parallel by significant decrease of pores, the position and the existence of tetrahedral and octahedral sites. The FT-IR spectra reveal the metal–oxygen oscillations at tetrahedral and octahedral sites. The dielectric constants are found in the range −118.6 to −242.5 at 2 MHz, which revealed moderate strain sensitivity, low ac conductivity and low dielectric loss. At low frequency range the synthesized samples are promising materials for stress sensor applications. [ABSTRACT FROM AUTHOR]

Metallic biomaterials, such as stainless steels, cobalt–chromium–molybdenum (Co–Cr–Mo) alloys, and titanium (Ti) alloys, have long been used as load-bearing implant materials due to their metallic mechanical strength, corrosion resistance, and biocompatibility. However, their magnetic susceptibility and elastic modulus of more than 100 GPa significantly restrict their therapeutic applicability. In this study, spinodal Zr 60 Nb 40 , Zr 50 Nb 50 , and Zr 40 Nb 60 (at.%) alloys were selected from the miscibility gap based on the Zr–Nb binary phase diagram and prepared by casting, cold rolling, and aging. Their microstructure, mechanical properties, corrosion resistance, magnetic susceptibility, and biocompatibility were systematically evaluated. Spinodal decomposition to alternating nanoscale Zr-rich β 1 and Nb-rich β 2 phases occurred in the cold-rolled Zr–Nb alloys during aging treatment at 650 °C. In addition, a minor amount of α phase was precipitated in Zr 60 Nb 40 due to the thermodynamic instability of the Zr-rich β 1 phase. Spinodal decomposition significantly improved the mechanical strength of the alloys due to nanosized dual-cubic reinforcement. The Zr–Nb alloys showed an electrochemical corrosion rate of 94–262 nm per year in Hanks' solution because of formation of dense passive films composed of ZrO 2 and Nb 2 O 5 during the polarization process. The magnetic susceptibilities of the Zr–Nb alloys were significantly lower than those of commercial Co–Cr–Mo and Ti alloys. The cell viability of the Zr–Nb alloys was more than 98 % toward MC3T3-E1 cells. Overall, the spinodal Zr–Nb alloys have enormous potential as bone-implant materials due to their outstanding overall mechanical properties, extraordinary corrosion resistance, low magnetic susceptibility, and sufficient bicompatibility. This work reports on spinodal Zr–Nb alloys with heterostructure. Spinodal decomposition significantly improved their mechanical strength due to the nanosized dual-cubic reinforcement. The Zr–Nb alloys showed large corrosion resistance in Hanks' solution because of formation of dense passivation films composed of ZrO 2 and Nb 2 O 5 during the polarization process. The magnetic susceptibilities of the Zr–Nb alloys were significantly lower than those of commercial Co–Cr–Mo and Ti alloys. The cell viability of the Zr–Nb alloys was more than 98 % toward MC3T3-E1 cells. The results demonstrate that spinodal Zr–Nb alloys have enormous potential as bone-implant materials due to their outstanding overall mechanical properties, high corrosion resistance, low magnetic susceptibility, and sufficient biocompatibility. [Display omitted] [ABSTRACT FROM AUTHOR]

The article investigates the effect of the specific magnetic susceptibility χ0 of 06ХН28МДТ alloy (similar to AISI 904L steel) on its corrosion behaviour in recycled water of enterprises, which most often has a pH of 4-8 and a chloride concentration of up to 600 mg/l. Under such conditions, heat exchangers made of this alloy melt can be subject to pitting. Their resistance to pitting corrosion is estimated by means of the critical temperatures (CPT) in modelrecycled water with the following parameters. In particular, it has been found that the chlorides' concentration within them has a more intense effect on the alloy CPT than their pH, since it increases up to 8°C with an increase in pH from 4 up to 8 and up to 11°C with a decrease in chlorides' concentration from 600 down to 350 mg/l. It is found that, in the model recycled water with pH 4 and chlorides' concentration of 350 mg/l, the CPT of the alloy decreases from 53°C down to 46°C, and with chlorides' concentration of 600 mg/l from 42°C down to 38°C with an increase in its parameter χ0 from 2.86 m³/kg up to 3.09 m³/kg. However, its further increase up to 3.38 m³/kg contributes to the elevation of the CPT up to 49°C in media with pH 4 and 350 mg/l and up to 40°C with pH 4 and 600 mg/l. This corrosion behaviour of the alloy is due to the synergistic effect of the alloy high χ0, the maximum content of titanium nitrides and sulphides, and the characteristic features of the selective dissolution of ΔCr, ΔNi and ΔFe from pits. In particular, under such conditions, they are stable and develop steadfastly, since the coefficients of selective dissolution of Cr ZCr < 1 and Ni ZNi > 1. [ABSTRACT FROM AUTHOR]

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Cerium doped Mn0.5Zn0.5Fe2O4 spinel nano-magnets were synthesized using sol–gel technique and characterized through x-ray diffraction (XRD), Fourier transform-infrared radiation (FT-IR), impedance analyzer, modulus spectroscopy, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and energy dispersive x-ray spectroscopy (EDX). The cations redistribution with Ce3+ substitution strongly affect the physical properties of the samples. Single phase spinel structure is identified for the synthesized samples and the crystal imperfection is found low. The lattice parameters reduce with Ce3+ concentration due to lanthanide contraction. The saturation magnetization of Mn0.5Zn0.5CexFe2−xO4 is found maximum for the x = 0 sample. The measured magnetic properties such as coercivity (Hc), retentivity (Mr) and saturation magnetization (Ms) decrease with increase in Ce3+ concentration. The synthesized samples show positive values of magnetic susceptibility which show anti-ferromagnetic/ferrimagnetic nature. The SEM images show increase in size of the grain with increasing sintering conditions parallel by significant decrease of pores, the position and the existence of tetrahedral and octahedral sites. The FT-IR spectra reveal the metal–oxygen oscillations at tetrahedral and octahedral sites. The dielectric constants are found in the range −118.6 to −242.5 at 2 MHz, which revealed moderate strain sensitivity, low ac conductivity and low dielectric loss. At low frequency range the synthesized samples are promising materials for stress sensor applications. [ABSTRACT FROM AUTHOR]

The investigation results of magnetization, dynamic magnetic susceptibility and microstructure of samples of second generation high-temperature superconducting wires irradiated by Bi ions at room temperature with energy of 670 MeV and fluences of 1011 and 1012 cm–2 are presented. The dependences of the superconducting transition temperature and critical current density on the fluence have been determined. For the sample irradiated to fluence 1011 cm–2, an increase in the critical current density is observed compared to the control nonirradiated sample. The microstructure analysis of irradiated samples demonstrates the presence of amorphous tracks, which can act as effective pinning centers. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility imaging may provide valuable information about chemical composition and microstructural organization of tissue. However, its estimation from the MRI signal phase is particularly difficult as it is sensitive to magnetic tissue properties ranging from the molecular to the macroscopic scale. The MRI Larmor frequency shift measured in white matter (WM) tissue depends on the myelinated axons and other magnetizable sources such as iron‐filled ferritin. We have previously derived the Larmor frequency shift arising from a dense medium of cylinders with scalar susceptibility and arbitrary orientation dispersion. Here, we extend our model to include microscopic WM susceptibility anisotropy as well as spherical inclusions with scalar susceptibility to represent subcellular structures, biologically stored iron, and so forth. We validate our analytical results with computer simulations and investigate the feasibility of estimating susceptibility using simple iterative linear least squares without regularization or preconditioning. This is done in a digital brain phantom synthesized from diffusion MRI measurements of an ex vivo mouse brain at ultra‐high field. [ABSTRACT FROM AUTHOR]