The Divalent Lanthanoid Triflates Ln(CF3SO3)2(CH3CN) (Ln=Sm, Eu): Structure, Luminescence, and Magnetism

The reaction of the trivalent lanthanoide triflates Ln(OTf)3 (Ln=Sm, Eu; OTf=CF3SO3 -) with the respective metals in acetonitrile leads to the Ln(II)-triflates Eu(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1053.54(1), b=610.28(5), c=1946.92(2) pm, β =98.611(4)) and Sm(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1054.41(4), b=612.16(2), c=1952.65(7) pm, β =98.524(2)). The isotypic strontium compound Sr(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1056.39(5), b=610.05(3), c=1950.1(1) pm, β =98.900(2)°) has been obtained from SrCO3 and triflic acid. The compounds have been investigated by X-ray diffraction, vibrational spectroscopy, luminescence spectroscopy, cyclic voltammetry, thermal analysis, and magnetic measurements.

Magnetism and electronic properties of ConMoP (n = 1 ~ 5) cluster: a DFT study

CONTEXT

Hydrogen has emerged as a promising clean energy carrier, underscoring the imperative need to comprehend its adsorption mechanisms. This study delves into the magnetic and electronic properties of Co-Mo-P clusters, aiming to unveil their catalytic potential in hydrogen production. Employing density functional theory (DFT), we optimized cluster configurations and scrutinized their magnetic behaviors. Our investigation unveiled 16 stable configurations of the ConMoP (n = 1 ~ 5) cluster, predominantly in steric forms. The magnetic attributes were primarily ascribed to the d orbitals of Co metal atoms, with Co3MoP exhibiting exceptional magnetic characteristics. Analysis of density of state diagrams revealed the prevalence of spin-up α-electrons in d orbitals, while spin-down β-electrons attenuated overall magnetic properties. Localized orbital (LOL) analysis highlighted stable covalent bonds within the clusters, affirming their catalytic potential. Orbital delocalization index (ODI) analysis revealed diverse spatial distribution ranges for orbitals across different configurations, suggesting a progressive attenuation of off-domain properties with increasing cluster size. Furthermore, infrared spectroscopy unveiled distinct vibrational peaks in various configurations, indicative of unique infrared activities. These findings contribute to a nuanced theoretical understanding of Co-Mo-P clusters and pave the path for future research aimed at augmenting their catalytic efficiency in hydrogen production. This study underscores the viability of Co-Mo-P clusters as alternatives to conventional Pt catalysts, offering insights into the design of novel materials for sustainable energy applications. Further research is warranted to explore the behavior of the Co-Mo-P system under diverse reaction conditions, fostering advancements in materials and energy science.

METHODS

In this study, we harnessed the ConMoP (n = 1 ~ 5) cluster as a simulation platform for probing the local structure of the material. Our aim was to scrutinize the magnetism, electronic characteristics influenced by the varying metal atoms within these clusters. A systematic exploration involved incrementing the number of metal atoms and expanding the cluster size to elucidate the corresponding property variations. Density functional theory (DFT) calculations were pivotal to our methodology, employing the B3LYP hybrid functional implemented in the Gaussian 16 software package. The ConMoP (n = 1 ~ 5) cluster underwent optimization calculations and vibrational analysis at the def2-tzvp quantization level, yielding optimized configurations with diverse spin multiplet degrees. To comprehensively characterize and visually represent the stability, electronic features, and catalytic attributes of these configurations, we employed a suite of computational tools. Specifically, quantum chemistry software GaussView and wave function analysis software Multiwfn played integral roles. Through the integrated use of these computational tools, we acquired valuable insights into the magnetism, electronic characteristics of the ConMoP (n = 1 ~ 5) cluster, shedding light on their dependency on distinct metal atoms.

Changing the spin disorder of two-dimensional magnetic Cr2TiC2Tx to long-range order through noble metal adhesion

To enhance the use of Cr2TiC2Tx MXene in spin electronics, it is essential to transform its spin-disordered state into a long-range ordered spin state. In this study, first-principles calculations show that Rh layers adhered to the Cr2TiC2Tx surfaces can transform its spin disordered state into a long-range spin order by donating electrons to the O terminations, resulting in Cr2TiC2Tx becoming a single-layer A-type antiferromagnet. As the proportion of F termination increases from 0 to 100%, the exchange coupling constant J1 of the compound escalates from 0.5 to 15.9 meV. Concurrently, the Néel temperature experiences a significant rise from 8 K to 110 K. The analysis of the density of states reveals that the obtained Cr2TiC2Tx exhibits excellent conductivity with O termination and semiconductor characteristics with F termination. These unique features make Cr2TiC2Tx a promising magnetic material for application in spin electronics.

Influence of shock waves on bifunctional nickel particles: Enhancing magnetic properties and supercapacitor applications

In the present study, shock-wave impact experiments were conducted to investigate the structural properties of nickel metal powder when exposed to shock waves. Both X-ray diffractometry and scanning electron microscopy were used to evaluate the structural and surface morphological changes in the shock-loaded samples. Notably, the experimental results revealed variations in lattice parameters and cell structures as a function of the number of shock pulses and the increasing volume. The transition occurred from P2 (100 shocks) to P3 (200 shocks). Remarkably, P5 (400 shocks) exhibited attempts to return to its initial state, and intriguingly, P4 displayed characteristics reminiscent of the pre-shock condition. Additionally, significant morphological changes were observed with an increase in shock pulses. Magnetic measurements revealed an increase in magnetic moment for P2, P3, and P4, but a return to the original state was observed for P5. Moreover, the capacitance exhibited an upward trend with increasing shock pulses, except for P5, where it experienced a decline. These findings underscore the significant impact of even mild shock waves on the physical and chemical characteristics of bifunctional nickel particles. This research sheds light on the potential applications of shock wave-induced structural changes in enhancing the magnetic properties and supercapacitor performance of nickel particles.

Synthesis, Optical, Dielectric, SHG, Magnetic and Visible Light Driven Catalytic Studies on Compounds Belonging to the Swedenborgite Structure

A new compound, InBaZn3 GaO7 , with swedenborgite structure along with transition metal (TM) substituted variants have also been prepared. The structure contains layers of tetrahedral ions (Zn2+ /Ga3+ ) connected by octahedrally coordinated In3+ ion forming the three-dimensional structure with voids where the Ba2+ ions occupy. The TM substituted compounds form with new colors. The origin of the color was understood based on the ligand-field transitions. The near IR reflectivity studies indicate that the Ni - substituted compounds exhibit good near - IR reflectivity behavior, making them possible candidates for 'cool pigments'. The temperature dependent dielectric studies indicate that the InBaZn3 GaO7 compound undergoes a phase transition at ~360 °C. The compounds are active towards second harmonic generation (SHG). Magnetic studies show the compounds, InBaZn2 CoFeO7 and InBaZn2 CuFeO7 to be anti-ferromagnetic in nature. The copper containing compounds were found to be good catalysts, under visible light, for the oxidation of aromatic alkenes. The many properties observed in the swedenborgite structure-based compounds suggests that the mineral structure offers a fertile ground to investigate newer compounds and properties.

Magnetic Tunability in Tetragonal Mn-Rh-Ir-Sn Inverse Heusler Compounds

Gaining control over magnetic structure has been an ongoing challenge in materials that form complex, nanoscale, non-collinear magnetic configurations. Recently, it was predicted that tuning the ratio of the Dzyaloshinskii-Moriya interaction to the uniaxial magnetic anisotropy in tetragonal inverse Heuslers through changes in composition could allow a range of interesting magnetic states to be accessed, from simple ferrimagnetism, to helical and antiskyrmionic phases. Here, we show tunability of the magnetic phase behavior in the Mn--Rh--Sn system through Ir substitution on the Rh substructure. Iridium substitution correlates to an increase in the strength of ferromagnetic exchange couplings, at the expense of antiferromagnetic exchange couplings. However, we do not observe the complex non-collinear magnetic phases proposed previously, likely due to the extremely narrow composition window where these phases are predicted to form in a bulk sample. This work highlights the sensitivity of complex magnetic structures to stoichiometry, which makes them difficult to discover empirically.

Covalent immobilization of lipase on magnetic biochar for one-pot production of biodiesel from high acid value oil

Magnetic biochar was synthesized via chelation of Fe3+ with carboxymethyl cellulose and pyrolysis for covalently immobilizing Eversa® Transform lipase. The magnetic biochar had 75.8 mg/g lipase loading that was 54.1 % higher than that without magnetism. The immobilized lipase achieved 91.3 mg/g lipase loading with 19.2 U/mg lipase activity after optimization. It showed good thermal and acid stability with 82.5 % and 98.2 % relative activity at 45 °C and pH 4, respectively. Its relative activity was 90.8 % after stored for 30 d at 4 °C. After magnetically separated for 10 cycles, it still kept 70.1 % activity due to the strong covalent bonding. The lipase further catalyzed one-pot esterification and transesterification of high acid value oil (38 mg KOH/g) with 95.7 % biodiesel yield and cycled for 10 times at 85.7 % yield. Kinetic study gave the activation energy of 28.7 kJ/mol. The covalently immobilized lipase could find practical applications.

Wire-in-tube nanofiber as one side to construct specific-shaped Janus nanofiber with improved upconversion luminescence and tunable magnetism

It is an important strategy to rationally design and construct specific-shaped microscopic nanostructures for developing poly-functional nanomaterials for different advanced applications. In this work, a novel technique combining a parallel electrospinning with a subsequent bi-crucible fluorination is advanced and utilized to facilely synthesize a brand-new peculiar one-dimensional (1D) wire-in-tube nanofiber//nanofiber shaped Janus nanofiber (WJNF) to refrain from usual complicated preparation procedures. Partition of four independent domains in the peculiar-structured Janus nanofiber is microscopically realized. The Janus nanofiber with four microscopic partitions can be applied to assemble various functions to avoid adverse mutual impacts among functions to realize multi-functionalization of the materials. As a case study, [YF3:Yb3+, Er3+@SiO2]//CoFe2O4 WJNFs with synchronous excellent upconversion luminescence and tunable magnetism are designed and constructed by the above technique. One side of the WJNF is composed of YF3:Yb3+, Er3+@SiO2 wire-in-tube nanofiber with YF3:Yb3+, Er3+ nanofiber as core layer and SiO2 as shell layer, and the other side is composed of CoFe2O4 magnetic nanofiber. YF3:Yb3+, Er3+ green upconversion luminescent nanofiber is completely separated from CoFe2O4 to fully avoid the weakening of luminescent intensity caused by the direct contact between luminescent and magnetic substances, and thus the luminescent intensity of [YF3:Yb3+, Er3+@SiO2]//CoFe2O4 WJNFs is apparently enhanced. Up-conversion luminescent intensity and magnetism of the WJNFs are modulated by tuning the contents of CoFe2O4. With the increase of CoFe2O4 content, the saturation magnetization of the WJNFs increases from 3.91 to 12.90 emu·g-1, revealing the tunable magnetism of the product. The formation mechanism of WJNFs is advanced, and a corresponding facile construction technique is established to shun complicated process, which provides theoretical guidance and technical support for the design and preparation of other poly-functional nanomaterials.

Fe/N co-doped magnetic porous hydrochar for chromium(VI) removal in water: Adsorption performance and mechanism investigation

Four kinds of Fe/N co-doped porous hydrochar were prepared by one/two-step N-doping schemes using microwave/traditional pyrolysis methods for removing Cr(VI) from aqueous phase. Heterocyclic-N was introduced through CO(NH2)2-based hydrothermal carbonization process, which could adjust the electronic structure of the hydrochar framework. Furthermore, Fe0 and Fe3O4 were embedded into hydrochar via carbothermal reduction reaction using FeCl3 as the precursor, which improved the reducibility and magnetism of the material. The modified hydrochar exhibited pH-dependency and rapid kinetic equilibrium, and the maximal adsorption amount of magnetic porous hydrochar obtained by microwave-assisted one-step N-doping (MP1HCMW) reached 274.34 mg/g. Meanwhile, the modified hydrochar had a high tolerance to multiple co-existing ions and the removal efficiency maintained above 73.91 % during five regeneration cycles. Additionally, MP1HCMW efficiently removed Cr(VI) via pore filling, electrostatic attraction, ion exchange, reduction, complexation, and precipitation. Summarily, Fe/N co-doped porous hydrochar was a feasible adsorbent with outstanding remediation potential for Cr(VI)-contaminated water.

Hundred-Fold Enhancement in the Anomalous Hall Effect Induced by Hydrogenation

The anomalous Hall effect (AHE) is one of the most fascinating transport properties in condensed matter physics. However, the AHE magnitude, which mainly depends on net spin polarization and band topology, is generally small in oxides and thus limits potential applications. Here, we demonstrate a giant enhancement of AHE in a LaCoO3-induced 5d itinerant ferromagnet SrIrO3 by hydrogenation. The anomalous Hall resistivity and anomalous Hall angle, which are two of the most critical parameters in AHE-based devices, are found to increase to 62.2 μΩ·cm and 3%, respectively, showing an unprecedentedly large enhancement ratio of ∼10000%. Theoretical analysis suggests the key roles of Berry curvature in enhancing AHE. Furthermore, the hydrogenation concomitantly induces the significant elevation of Curie temperature from 75 to 160 K and 40-fold reinforcement of coercivity. Such giant regulation and very large AHE magnitude observed in SrIrO3 could pave the path for 5d oxide devices.

Coexistence of Electron and Phonon Topology in Conjunction with Quantum Transport Device Modeling

The escalating research in the field of topology necessitates an understanding of the underlying rich physics behind the materials possessing unique features of non-trivial topology in both electronic and phononic states. Due to the interaction between electronic quasiparticles and spin degrees of freedom, the realization of magnetic topological materials has opened up a new frontier with unusual topological phases, however, these are rarely reported alongside phononic quasiparticle excitations. In this work, by virtue of first principles calculations and symmetry analysis, the intermetallic ferromagnetic compounds MnGaGe and MnZnSb with the coexistence of exceptional topological features in the electronic and phononic states are proposed. These compounds host nodal surface on ky= π plane in bulk Brillouin zone (BZ) in the electronic and phononic spectra protected by the combination of time-reversal symmetry and nonsymmorphic two-fold screw-rotation symmetry. In the former case, spin-polarized nodal surface is present in the majority and minority spin channels and found to be robust to ground-state magnetic polarization. The presence of nodal line features is analyzed in both the quasiparticle spectra, whose non-trivial nature is confirmed by the Berry phase calculation. The incorporation of spin-orbit coupling (SOC) in the electron spectra introduces distinctive characteristics in the transport properties, facilitating the emergence of anomalous Hall conductivity (AHC) by means of Berry curvature (BC) in both bulk and monolayer. Furthermore, the monolayer has been proposed as a two-terminal device model to investigate the quantum transport properties using the non-equilibrium Green's function (NEGF) approach. This superlative combination of observations and modeling sets the path for a greater level of insight into the behavior and aspects of topological materials at the atomic scale.

Synthetic of functionalized magnetic titanium-based metal-organic frameworks to efficiently remove Hg(Ⅱ) from wastewater

The rapid development of process technology has led to rapid daily industrial production, which also produced a large amount of waste liquid. At the same time, the existing treatment technology cannot keep up with the demand, resulting in the malicious destruction of the environment by wastewater, especially mercury-containing wastewater was very harmful. Effective means of removing mercury ions need to be found. With magnetic ferric oxide as the core and titanium-based metal-organic frameworks as the shell, a new type of magnetic adsorbent (BTA-MIL-125(Ti)@Fe3O4) was synthesized. Materials were tested by multiple characterization methods and multiple sets of experiments. At optimal pH 6, the removal rate in 100 ppm Hg(Ⅱ) was as high as 95.8%. The theoretical adsorption capacity was 615 mg/L. Isothermal experiments, kinetic experiments and thermodynamic experiments have respectively verified that the material was a kind of adsorption material with self-emission heat based on chemical action and synergistic adsorption with Hill model. By simulating the immunity of a variety of ions (Cu, Zn, Mg, Ni, Cd), the material itself also exhibited a very high affinity for Hg(Ⅱ). The results of five high-cycle stable adsorption proved the repeatable stability of the material itself. Various characterization methods have also shown that nitrogen and sulfur-containing groups chelated with Hg(Ⅱ). All of the above was enough to show that the BTA-MIL-125(Ti)@Fe3O4 was a magnetic adsorption material with excellent performance and great prospects.

Spectromicroscopic study of the transformation with low energy ions of a hematite thin film into a magnetite/hematite epitaxial bilayer

The search of new properties in novel oxide heterostructures requires the exploration of new fabrication methods and the study, at the microscopic level, of the processes involved during the synthesis. We present a synchrotron-based spectromicroscopic investigation of a magnetite/hematite bilayer on Pt(111) grown in a two-step process by thermal evaporation and Low Energy Ion Bombardment (LEIB). The characterization includes the study of structural, electronic, chemical, and magnetic properties using X-ray Absorption Spectroscopy (XAS), Low Energy Electron Microscopy (LEEM), Photoemission Electron Microscopy (PEEM), or X-ray Magnetic Circular Dichroism (XMCD). The aim is to obtain microscopic information of the thin film before, during, and after the ion bombardment. Ion bombardment gradually transforms the topmost layers of the hematite thin film into a defective sub-oxide, where magnetite nuclei grow and coalesce with increasing ion doses. Two rotational domains of magnetite coexist, which are typically a few tens of nanometres large and do not grow significantly with temperature annealings. The incoherent growth of the magnetite nuclei favours the formation of stable twin boundaries (TBs) and antiphase boundaries (APBs). Dichroic spectra show the characteristics of the ferrimagnetic (FiM) order of magnetite, and the spatial distribution of magnetic domains shows no apparent correlation with the structural image, displaying smooth domains separated by diffuse frontiers. These findings illustrate the importance of a spectromicroscopic characterization of novel oxide heterostructures for potential future applications.

Preparation of room-temperature phosphorescence-ratiometric fluorescence magnetic mesoporous imprinted microspheres and its application in detection of malachite green and tartrazine in multimatrix

The photoluminescent properties of Mn-doped ZnS quantum dots were fully exploited, and room-temperature phosphorescence (RTP)-ratiometric fluorescence (RF) magnetic mesoporous molecularly imprinted polymers (PFMM-MIPs) were prepared by integrating molecular imprinting technology. RTP was used to detect malachite green (MG). The fluorescence at 420 nm and the peak at 590 nm in the fluorescence mode were used as the response reference signals respectively to detect tartrazine (TZ). The linear responsive range and detection limit of MG were 0.01-150 μM and 4.3 nM, and these of TZ were 0.05-80 μM and 23.7 nM. RTP, which can avoid the interference of background fluorescence, and RF with self-calibration ability can both largely weaken the matrix effect. This work enables single-probe-type MIPs to achieve dual-target analysis via RTP and RF. This method provides excellent sensitivity, specificity, recovery and recyclability, and is expected to be prospectively applied in the fields of food, environment and biological analyses.

Fe3O4-lignin@Pd-NPs: A highly active, stable and broad-spectrum nanocomposite for water treatment

In this work, we report an environmentally friendly renewable nanocomposite magnetic lignin-based palladium nanoparticles (Fe3O4-lignin@Pd-NPs) for efficient wastewater treatment by decorating palladium nanoparticles without using any toxic reducing agents on the magnetic lignin abstracted from Poplar. The structure of composite Fe3O4-lignin@Pd-NPs was unambiguously confirmed by XRD, SEM, TEM, EDS, FTIR, and Zeta potential. After systematic evaluation of the use and efficiency of the composite to remove toxic organic dyes in wastewater, some promising results were observed as follows: Fe3O4-lignin@Pd-NPs exhibits highly active and efficient performance in the removal of toxic methylene blue (MB) (up to 99.8 %) wastewater in 2 min at different concentrations of MB and different pH values. Moreover, except for toxic MB, the other organic dyes including Rhodamine B (RhB), Rhodamine 6G (Rh6G), and Methyl Orange (MO) can also be removed efficiently by the composite. Finally, the easily recovered composite Fe3O4-lignin@Pd-NPs exhibits well stability and reusability, and catalytic efficiency is maintained well after ten cycles. In conclusion, the lignin-based magnetism Pd composite exhibits powerful potential practical application in industrial wastewater treatment.

Length-Dependent Magnetic Evolution of Anthenes on Au(111)

Nanographenes with zigzag edges, for example, anthenes, exhibit a unique nonbonding π-electron state, which can be described as a spin-polarized edge state that yields specific magnetic ground state. However, prior researches on the magnetism of anthenes with varying lengths on a surface is lacking. This study systematically fabricated anthenes with inherent zigzag carbon atoms of different lengths ranging from bisanthene to hexanthene. Their magnetic evolution on the Au(111) surface was analyzed through bond-resolved scanning probe techniques and density functional theory calculations. The analyses revealed a transition in magnetic properties associated with the length of the anthenes, arising from the imbalance between hybridization energy and the Coulomb repulsion between valence electrons. With the increasing length of the anthenes, the ground state transforms gradually from a closed-shell to an antiferromagnetic open-shell singlet, exhibiting a weak exchange coupling of 4 meV and a charge transfer-induced doublet. Therefore, this study formulated a chemically tunable platform to explore size-dependent π magnetism at the atomic scale, providing a framework for research in organic spintronics.

Efficacy of green infrastructure in reducing exposure to local, traffic-related sources of airborne particulate matter (PM)

One aim of roadside green infrastructure (GI) is to mitigate exposure to local, traffic-generated pollutants. Here, we determine the efficacy of roadside GI in improving local air quality through the deposition and/or dispersion of airborne particulate matter (PM). PM was collected on both pumped air filters and on the leaves of a recently installed 'tredge' (trees managed as a head-high hedge) at an open road environment next to a primary school in Manchester, U.K. The magnetic properties of PM deposited on leaves and filters (size fractions PM10 and PM2.5) were deduced from hysteresis loops, first-order reversal curves (FORCs), and low-temperature remanence measurements. These were complemented with electron microscopy to identify changes in magnetic PM concentration downwind of the tredge/GI. We show that the tredge is permeable to airflow using a simple CO2 tracer experiment; hence, it allows interception and subsequent deposition of PM on its leaves. Magnetic loadings per m3 of air from filters (PM10 saturation magnetisation, Ms, at 5 K) were reduced by 40 % behind the tredge and a further 63 % in the playground; a total reduction of 78 % compared to roadside air. For the PM2.5 fraction, the reduction in magnetic loading behind the tredge was remarkable (82 %), reflecting efficient diffusional capture of sub-5 nm Fe-oxide particles by the tredge. Some direct mixing of roadside and playground air occurs at the back of the playground, caused by air flow over, and/or through gaps in, the slowly-permeable tredge. The magnetic loading on tredge leaves increased over successive days, capturing ~23 % of local, traffic-derived PM10. Using a heuristic two-dimensional turbulent mixing model, we assess the limited dispersion of PM < 22.5 μm induced by eddies in the tredge wake. This study demonstrates that PM deposition on leaves reduces exposure significantly in this school playground setting; hence, providing a cost-effective mitigation strategy.

One-pot synthesis of versatile sphere-like nano adsorbent MnAl2O4 (MAO): an optical and magnetic material for efficient fluoride removal and latent finger print detection

Spherically shaped trimetallic MnAl2O4 (MAO) nanoadsorbent was prepared in an one-pot synthesis process for the removal of excess fluoride from water. The adsorbent was characterized by thermogravimetric analysis (TGA), X-ray diffraction study (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), etc. The adsorption property for fluoride on the MAO was analyzed by batch experiments varying the adsorbent dose, pH, contact time, and initial fluoride concentration. The results showed that the fluoride uptake behavior of the samples could precisely be fitted by the Freundlich model, and the maximum adsorption capacity was estimated to be 39.21 mg/g at room temperature. The pseudo-second-order models accurately described the adsorption kinetics data. The regenerated sample showed excellent reusability along with high removal capacity on real water sample also. The underlying fluoride adsorption mechanism via ion-exchange and electrostatic interaction was established from X-ray photoelectron spectroscopy (XPS) and zeta potential studies. The sample showed excellent luminescence with blue emission with a band gap of 2.6 eV. The materials also showed good elastic behavior exhibiting the Poisson's ratio (σ) 0.32 and excellent latent figure print detection capacity distinguishing the clearly the ridge and furrow regions under UV light. The magnetic behavior was also found to be in long range with antiferromagnetic characteristics.

Effect mechanism of iron conversion on adsorption performance of hydrochar derived from coking sludge

In this study, Fe conversion during hydrothermal carbonization (HTC) of coking sludge were investigated, and the effect mechanism of Fe component on the adsorption performance of coking sludge hydrochar (CHC) was explored. The results showed that after HTC treatment, more than 95 % of Fe remained in the CHC. Fe3+ was reduced to Fe2+ by sugar and amino acids. Fe was stabilized during the HTC process and was still predominantly in the Fe manganese oxidation state. The CHC prepared at 270 °C exhibited excellent adsorption capacities for Congo red (CR), tetracycline (TC), and Cr (VI). Their maximum adsorption capacities were 140.85, 147.06, and 19.92 mg/g, respectively. Quantitative adsorption mechanism experiments, XRD and VSM characterization revealed that Fe component played a significant role in adsorption, and CHC with more Fe3O4 exhibited better adsorption capacity. The results of the XPS characterization of CHC before and after adsorption showed that Fe3O4 provided rich Fe adsorption sites on the surface of CHC to strengthen the adsorption efficiency of pollutants through Fe3+/Fe2+ reduction and complexation of Fe-O/N. In addition, the formed Fe3O4 also imparted CHC with magnetic properties (Ms = 4.12 emu/g) to facilitate the subsequent separation and recovery. These results demonstrated that the prepared CHC has great potential for treating actual wastewater containing CR and TC.

Interaction-driven Chern insulating phases in the α-T3 lattice with Rashba spin-orbit coupling

The magnetic interaction is a necessary ingredient to break the time-reversal symmetry in realizing quantum anomalous Hall, or Chern insulating phases. Here, we study topological phases in the α - T 3 model, a minimal theoretical model supporting the flat band, taking account of Rashba spin-orbit coupling and flat-band-induced spontaneous ferromagnetism. By analyzing the interaction-driven phase diagrams, band structures, topological edge states, and topological invariants, we demonstrate that this system offers a platform for realizing a wide range of phases, including normal insulators, semimetals, and Chern insulators. Uniquely, there exist both high-Chern-number insulators and valley-polarized Chern insulators. In the latter phase, edge channels exist in the single valley, leading to nearly 100 % valley polarization. These findings demonstrate the potential of interaction-driven systems in realizing exotic phases and their promising role in future applications in topology electronics and valleytronics.

Synthesis of magnetic sodium lignosulfonate hydrogel(Fe3O4@LS) and its adsorption behavior for Cd2+ in wastewater

Heavy metal pollution is becoming increasingly serious. Heavy metal pollutants are nonbiodegradable and can be bioenriched through the food chain, and thus, they greatly threaten the environment and human health. Hydrogels, as an ideal adsorbent, have been widely used to treat heavy metal industrial wastewater. Sodium lignosulfonate hydrogel (LS) was prepared by free-radical grafting copolymerization, and nano-Fe3O4 particles were loaded in LS by an in-situ precipitation method (Fe3O4@LS). The magnetic properties and adsorption capacity of Fe3O4@LS are closely related to the load capacity of Fe3O4. XRD, FTIR, XPS, SEM, TEM, BET, and TGA analyses of the materials were performed. Subsequently, the removal effect of the typical pollutant Cd2+ in heavy metal-polluted water was studied with Fe3O4@LS as the adsorbent. The influences of the Fe3O4@LS dosage and initial pH were investigated, and the adsorption kinetics and thermodynamics were further explored and discussed. Finally, the adsorption mechanism of Fe3O4@LS on Cd2+ was obtained. Results show that Fe3O4@LS has a more stable spatial network structure than LS, and the pore size, specific surface area and active sites increase. The maximum adsorption capacity can reach 88.00 mg/g when pH = 6 and the dosage of Fe3O4@LS is 1000 mg/L. The adsorption of Cd2+ by Fe3O4@LS conforms to pseudosecond-order kinetics and the Temkin isothermal adsorption model. Further mechanistic investigations show that the sorption of Cd2+ on Fe3O4@LS is mainly attributed to surface complexation, electrostatic attraction and coprecipitation. The coexistence of cations in water will inhibit the adsorption of Fe3O4@LS. Fe3O4@LS has superparamagnetism and a good response to an external magnetic field. The adsorption rate can still reach >60 % after four elutions with NaCl as the eluent. This material can be reused and has good application potential.

In-situ conversion of geopolymer into novel floral magnetic sodalite microspheres for efficient removal of Cd(II) from water

In the present work, a novel, floral-like, magnetic sodalite microsphere (SODM) was synthesized in situ by using fly ash (FA) and metakaolin (MK) as raw materials and was used to remove Cd(II) from water. Its magnetism can solve the problems of adsorbent recovery and possible secondary pollution. During the static adsorption, SODM shows a maximum adsorption capacity of 245.17 mg/g. The adsorption of Cd(II) on the SODM surface is spontaneous, exothermic, and physicochemical adsorption, which was evaluated by thermodynamics, kinetics, and isotherm studies. During dynamic adsorption, SODM shows a maximum adsorption capacity of 342.74 mg/g in the simulated solution prepared by the deionized water, compared to 215.88 mg/g in the simulated solution prepared using Xiangsi Lake water from Guangxi Minzu University. At 0.5 g SODM dosage in the dynamic adsorption, the adsorption capacity could rise to 632.81 mg/g. These results demonstrated the excellent Cd (II) adsorption performance of the SODM. The adsorption of cadmium on the SODM surface includes the synergistic effects of electrostatic attraction, ion exchange, and surface coordination reaction. Besides, the SODM shows good regeneration performance in both the deionized water and Xiangsi Lake water. The present study explores SODM as an adsorbent for the Cd (II) removal from wastewater and unbolts the industrial applicability of the SODM in the field of wastewater purification.

Super-efficient removal and adsorption mechanism of anionic dyes from water by magnetic amino acid-functionalized diatomite/yttrium alginate hybrid beads as an eco-friendly composite

The development of eco-friendly, large-capacity and easy-to-separate adsorbent materials has always been the focus and difficulty of adsorption technology in wastewater treatment applications based on the characteristics of dye wastewater. Therefore, in this study, a green magnetic glycine(Gly)-functionalized diatomite(Dia)/yttrium alginate (Y-SA) hybrid bead composite (Dia-Gly-Y-SA@Fe₃O₄) was synthesized by the droplet polymerization, and characterized by various modern analytical techniques. The adsorption performance and adsorption mechanism of the composite were evaluated and elucidated by the removal of anionic dyes direct Blue 106 (DB 106), Congo red (CR) and direct red 13 (DR 13) from water. The results show that the composite is a macroparticle gelpolymer with an average particle size of about 1.5 mm, flower-like fold surface structure, abundant porosity and sensitive magnetic response, and displays ultrastrong adsorption ability for three dyes. The adsorption equilibrium of each dye can be reached quickly within 30 min, and the removal efficiency is more than 95% at pH 2.0 and decreases slightly with pH up to 9.0. The adsorption processes could be explained by the Pseudo-second-order rate equation well. All isotherm data fitted the Langmuir model well, and the maximum adsorption capacities were 1635, 2359 and 1165 mg/g for DB 106, CR and DR 13 at 298 K, respectively. The ultrastrong adsorption performance was due to the multisite interaction of physicochemical action and various hydrogen bonds between hybrid beads and dye anions. As a cost-effective magnetic macroparticle adsorbent prepared by natural ingredients, Dia-Gly-Y-SA@Fe₃O₄ composite exhibits much more stronger adsorption efficiency, better collectability and no secondary pollution than powder Dia, and would have a good application prospect for the purification of anionic dye wastewater with a wide pH range.

Complex magnetism of single-crystalline AlCoCrFeNi nanostructured high-entropy alloy

We have investigated magnetism of the Al₂₈Co₂₀Cr₁₁Fe₁₅Ni₂₆ single-crystalline high-entropy alloy. The material is nanostructured, composed of a B2 matrix with dispersed spherical-like A2 nanoparticles of average diameter 64 nm. The magnetism was studied from 2 to 400 K via direct-current magnetization, hysteresis curves, alternating-current magnetic susceptibility, and thermoremanent magnetization time decay, to determine the magnetic state that develops in this highly structurally and chemically inhomogeneous material. The results reveal that the Cr-free B2 matrix of composition Al₂₈Co₂₅Fe₁₅Ni₃₂ forms a disordered ferromagnetic (FM) state that undergoes an FM transition at TC≈ 390 K. The Al- and Ni-free A2 nanoparticles of average composition Co₁₉Cr₅₆Fe₂₅ adopt a core-shell structure, where the shells of about 2 nm thickness are CoFe enriched. While the shells are FM, the nanoparticle cores are asperomagnetic, classifying into the broad class of spin glasses. Asperomagnetism develops below 15 K and exhibits broken-ergodicity phenomena, typical of magnetically frustrated systems.

Photoelectric structure and magnetic changes caused by niobium disulfide adsorbing (non)-metal atoms under defects

CONTEXT

The property transition between metal and semiconductor is the key to improving the properties of transition metal dichalcogenides (TMDCs). The adsorption of the NbS₂ compound in the defect state was adjusted for the first time. The hybrid system overwrites the original surface mechanism of NbS₂ and induces indirect band gaps. This modulation mode makes NbS₂ convert into a semiconductor and effectively improves the catalytic activity of the material in the system. In addition, the original local magnetic moment of the compound is concentrated in the vacancy region and is improved. The optical properties of the adsorption system indicate that NbS₂ compounds can be effectively applied in visible and low-frequency ultraviolet regions. This provides a new idea for the design of the NbS₂ compound as a two-dimensional photoelectric material.

METHODS

In the study, we assume that only one atom is adsorbed on the NbS₂ supercell of the defect, and the distance between the two adjacent atoms exceeds 12.74 Å, so the interaction between atoms is ignored in the study. Adsorbed atoms include nonmetallic elements (H, B, C, N, O, F), metallic elements (Fe, Co), and noble metal elements (Pt, Au, Ag). The density functional theory (DFT) was used in the experiment. The non-conservative pseudopotential method was used in the calculation to optimize the crystal structure geometrically. The approximate functional is Heyd-Scuseria-Ernzerhof (HSE06). The calculation method includes the spin-orbit coupling (SOC) effect. The crystal relaxation optimization uses a 7 × 7 × 1 k point grid to calculate niobium disulfide's photoelectric and magnetic properties. A vacuum space of 15Å is introduced in the direction outside the plane, and the free boundary condition is adopted to avoid the interaction between atomic layers. For the convergence parameter setting, the interatomic force of all composite systems is less than 0.03 eV/Å, and the lattice stress is less than 0.05 Gpa.

Rational design of recyclable metal-organic frameworks-based materials for water purification: An opportunity for practical application

Due to their high specific surface area (SSA), numerous active sites, and customizable pore structure, metal-organic frameworks (MOFs) have emerged as a popular topic in wastewater treatment research. Unfortunately, MOFs exist in the form of powder, which poses significant challenges such as difficult recycling and powder contamination in practical applications. Accordingly, for solid-liquid separation, the strategies of endowing magnetism and constructing appropriate device architectures are important. This review offers a detailed overview of the preparation strategies for recyclable MOFs-based magnetism and device materials and introduces the characteristics of these preparation methods through relevant instances. Besides, these two recyclable materials' applications and working mechanisms for removing pollutants from water through adsorption, advanced oxidation, and membrane separation technologies are introduced. The findings presented in this review will provide a valuable reference for the preparation of MOFs-based materials with excellent recyclability.

Passion fruit-inspired dendritic mesoporous silica nanospheres-enriched quantum dots coupled with magnetism-controllable aptasensor enable sensitive detection of ochratoxin A in food products

Ochratoxin A (OTA) is a powerful mycotoxin present in a variety of food products, and its detection is important for human health. Here, a fluorescent aptasensor is reported for sensitive OTA determination. Specifically, the surface of bio-inspired passion fruit-like dendritic mesoporous silica nanospheres-enriched quantum dots (MSNQs-apt) was first modified with the OTA aptamer as the recognition unit and fluorescence emitter, while the aptamer-complementary DNA (MNPs-cDNA) was linked with the magnetic nanoparticles (MNPs) as the separation element. In the range of 2.56 pg/mL to 8 ng/mL, the proposed aptasensor exhibited satisfactory linearity and a detection limit of 1.402 pg/mL. The developed aptasensor achieved recoveries of 90.98-103.20% and 94.33-107.57 % in red wine and wheat flour samples, respectively. By simply replacing the aptamer, this aptasensor can be easily extended to detection of other analytes, suggesting its potential as a universal detection platform for mycotoxins in food products.

First principles investigation of screened Coulomb interaction and electronic structure of low-temperature phase TaS2

By means of ab initio computation schemes, we examine the electronic screening, Coulomb interaction strength, and the electronic structure of a quantum spin liquid candidate monolayer TaS2 in its low-temperature commensurate charge-density-wave phase. Not only local (U) but non-local (V) correlations are estimated within random phase approximation based on two different screening models. Using GW + EDMFT (GW plus extended dynamical mean-field theory) method, we investigate the detailed electronic structure by increasing the level of non-local approximation from DMFT (V=0) to EDMFT and GW + EDMFT.

Research progress of novel magnetic two-dimensional carbon composites in photocatalytic degradation of pollutants: a review

With the improvement of economic level and the development of science and technology, the problem of water pollution needs to be solved now. Various water pollutants have a negative impact on nature and restrict its development. In recent years, photocatalysis is considered to be a promising wastewater treatment method. Two-dimensional carbon materials have become the hotspot of photocatalytic degradation of pollutants because of their excellent conductivity, large specific surface area, and good hydrophilicity. Nevertheless, it is very hard for these photocatalysts based on carbon materials to separate and recover from the system. For solving such a problem, the composition with magnetic components is an effective way which can facilitate separation and keep the catalytic activity of the samples. In this review, the main roles of magnetic carbon-based composites in the field of pollutant degradation are introduced, and their synthesis technology, classification, and application are summarized. In the end, the current challenges and prospects in this field are involved, aiming to provide useful insights and enlightments into the fields of pollutant treatment and photocatalytic degradation.

Simulations of magnetic Bragg scattering in transmission electron microscopy

We have simulated the magnetic Bragg scattering in transmission electron microscopy in two antiferromagnetic compounds, NiO and LaMnAsO. This weak magnetic phenomenon was experimentally observed in NiO by Loudon (2012). We have computationally reproduced Loudon's experimental data, and for comparison we have performed calculations for the LaMnAsO compound as a more challenging case, containing lower concentration of magnetic elements and strongly scattering heavier non-magnetic elements. We have also described thickness and voltage dependence of the intensity of the antiferromagnetic Bragg spot for both compounds. We have considered lattice vibrations within two computational approaches, one assuming a static lattice with Debye-Waller smeared potentials, and another explicitly considering the atomic vibrations within the quantum excitations of phonons model (thermal diffuse scattering). The structural analysis shows that the antiferromagnetic Bragg spot appears in between (111) and (000) reflections for NiO, while for LaMnAsO the antiferromagnetic Bragg spot appears at the position of the (010) reflection in the diffraction pattern, which corresponds to a forbidden reflection of the crystal structure. Calculations predict that the intensity of the magnetic Bragg spot in NiO is significantly stronger than thermal diffuse scattering at room temperature. For LaMnAsO, the magnetic Bragg spot is weaker than the room-temperature thermal diffuse scattering, but its detection can be facilitated at reduced temperatures.

Effects of weak static magnetic fields on the development of seedlings of Arabidopsis thaliana

To study magnetoreception of Arabidopsis thaliana, we analysed several developmental responses including cryptochrome-independent seed germination and the phytochrome- and cryptochrome-dependent hypocotyl elongation and photo-accumulation of anthocyanins and chlorophylls in weak static magnetic fields ranging from near null to 122 μT. A field of 50 μT accelerated seed germination by about 20 h relative to samples maintained in a near-null field. The double mutant, cry1cry2, lacking cryptochromes 1 and 2 displayed the same magnetic field-induced germination acceleration under blue light as the wild-type strain. Magnetic field-induced germination acceleration was masked in the presence of exogenous sucrose. Stimulus-response curves for hypocotyl elongation in a range between near-null to 122 μT indicated maxima near 9 and 60 μT for the wild-type strain as well as mutant cry1cry2. The photo-accumulation of anthocyanins and chlorophylls could be effectively modulated by magnetic fields in the presence of low-irradiance red and blue light, respectively. The findings indicate that Arabidopsis thaliana possesses light-independent mechanisms of magnetic field reception, which remain presently unidentified. Our results are in better agreement with predictions of the level crossing mechanism (LCM) of magnetoreception rather than those of the cryptochrome-associated radical-pair mechanism (RPM).

Optical micro-elastography with magnetic excitation for high frequency rheological characterization of soft media

The propagation of shear waves in elastography at high frequency (>3 kHz) in viscoelastic media has not been extensively studied due to the high attenuation and technical limitations of current techniques. An optical micro-elastography (OME) technique using magnetic excitation for generating and tracking high frequency shear waves with enough spatial and temporal resolution was proposed. Ultrasonics shear waves (above 20 kHz) were generated and observed in polyacrylamide samples. A cutoff frequency, from where the waves no longer propagate, was observed to vary depending on the mechanical properties of the samples. The ability of the Kelvin-Voigt (KV) model to explain the high cutoff frequency was investigated. Two alternative measurement techniques, Dynamic Mechanical Analysis (DMA) and Shear Wave Elastography (SWE), were used to complete the whole frequency range of the velocity dispersion curve while avoid capturing guided waves in the low frequency range (<3 kHz). The combination of the three measurement techniques provided rheology information from quasi-static to ultrasonic frequency range. A key observation was that the full frequency range of the dispersion curve was necessary if one wanted to infer accurate physical parameters from the rheological model. By comparing the low frequency range with the high frequency range, the relative errors for the viscosity parameter could reach 60 % and they could be higher with higher dispersive behavior. The high cutoff frequency may be predicted in materials that follow a KV model over their entire measurable frequency range. The mechanical characterization of cell culture media could benefit from the proposed OME technique.

Multiple roles of ferric chloride in preparing efficient magnetic hydrochar for sorption of methylene blue from water solutions

Highly efficient and cheap magnetic materials have application prospects in wastewater treatment. Herein, Fe₃O₄-loaded hydrochar (HC-Fe₃O₄) was obtained from hydrothermal carbonization (HTC) of bamboo with FeCl₃ and then added with FeCl₃ to form a magnetic sorbent via simple precipitation. The HC-Fe₃O₄ was characterized with various instruments. The characterizations show FeCl₃ plays at least two roles as a catalyst and an oxidant in HTC. The specific surface area of hydrochar enlarged from 39.9731 to 60.9887 m²·g^-1 after the addition of FeCl₃ during HTC, which showed FeCl₃ acted as a catalyst in HTC. XRD indicated Fe₃O₄ was formed by the structure of HC-Fe₃O₄, which indicated Fe(III) was reduced to Fe(II) during HTC. Sorption of methylene blue (MB) onto HC-Fe₃O₄ was better fitted by the Langmuir isotherm and pseudo-second-order kinetic models. Sorption is a spontaneous thermodynamic endothermic process and HC-Fe₃O₄ is easily separated by an applied magnetic field and reused.

Highly efficient fabrication of functional hepatocyte spheroids by a magnetic system for the rescue of acute liver failure

Engineering hepatocytes as multicellular cell spheroids can improve their viability after implantation in vivo for effective rescue of the devastating acute liver failure (ALF). However, there is still a lack of straightforward methods for efficient generation of functional hepatocyte spheroids. In this study, a magnetic system, consisting of magnetic microwell arrays and magnet blocks, is developed to realize magnetically controlled 3D cell capture and spatial confinement-mediated cell aggregation. The cell spheroids with smaller size show superior hepatic functions than the larger-sized counterparts. Notably, the intrinsic magnetism of magnetic microwell arrays can regulate superoxide anions in hepatocyte spheroids and herein promote various biological processes, including antioxidation, hepatocyte-related functions, and pro-angiogenic potential. Ectopic implantation of the functional cell spheroids in ALF-challenged mice significantly prolongs the animal survival, ameliorates inflammation, and promotes liver regeneration. Hence, application of the magnetic system for generation of functionally enhanced hepatocyte spheroids holds great potential for clinical translation in the future.

First-principles calculations of hematite (α-Fe(2)O(3)) by self-consistent DFT+U+V

Owing to the confined Fe-3d orbitals and self-interaction error of exchange-correlation functionals, approximate DFT fails to describe iron oxides electronic structure and magnetic properties accurately. Hybrid DFT or DFT + U can solve these problems, but the former is expensive, and the latter only considers on-site interactions. Here, we used DFT + U + V, a DFT + U extension including inter-site interactions, to simulate the structural, magnetic, and electronic properties, along with Fe and O K-edge XAS spectra of α-Fe₂O₃. Two types of atomic orbital projectors were studied, orthogonalized and non-orthogonalized. DFT + U + V improves the description of the structural, magnetic, and electronic properties of α-Fe₂O₃ compared to approximate DFT. The accuracy of the correction depends on the orbital projector used. DFT + U + V with orthogonalized projectors achieves the best experimental agreement at a fraction of hybrid DFT cost. This work emphasizes the importance of inter-site interactions and the type of atomic orbital projectors used in the theoretical research of α-Fe₂O₃.

Towards magnetism in pigeon MagR: Iron- and iron-sulfur binding work indispensably and synergistically

The ability to navigate long distances is essential for many animals to locate shelter, food, and breeding grounds. Magnetic sense has evolved in various migratory and homing species to orient them based on the geomagnetic field. A highly conserved iron-sulfur cluster assembly protein IscA is proposed as an animal magnetoreceptor (MagR). Iron-sulfur cluster binding is also suggested to play an essential role in MagR magnetism and is thus critical in animal magnetoreception. In the current study, we provide evidence for distinct iron binding and iron-sulfur cluster binding in MagR in pigeons, an avian species that relies on the geomagnetic field for navigation and homing. Pigeon MagR showed significantly higher total iron content from both iron- and iron-sulfur binding. Y65 in pigeon MagR was shown to directly mediate mononuclear iron binding, and its mutation abolished iron-binding capacity of the protein. Surprisingly, both iron binding and iron-sulfur binding demonstrated synergistic effects, and thus appear to be integral and indispensable to pigeon MagR magnetism. These results not only extend our current understanding of the origin and complexity of MagR magnetism, but also imply a possible molecular explanation for the huge diversity in animal magnetoreception.

Molecular Lanthanide Switches for Magnetism and Photoluminescence

Solvation of [(CNT)Ln(η⁸ -COT)] (Ln=La, Ce, Nd, Tb, Er; CNT=cyclononatetraenyl, i.e., C₉ H₉ ^- ; COT=cyclooctatetraendiid, i.e., C₈ H₈ ^2- ) complexes with tetrahydrofuran (THF) gives rise to neutral [(η⁴ -CNT)Ln(thf)₂ (η⁸ -COT)] (Ln=La, Ce) and ionic [Ln(thf)_x (η⁸ -COT)][CNT] (x=4 (Ce, Nd, Tb), 3 (Er)) species in a solid-to-solid transformation. Due to the severe distortion of the ligand sphere upon solvation, these species act as switchable luminophores and single-molecule magnets. The desolvation of the coordinated solvents can be triggered by applying a dynamic vacuum, as well as a temperature gradient stimulus. Raman spectroscopic investigations revealed fast and fully reversible solvation and desolvation processes. Moreover, we also show that a Nd:YAG laser can induce the necessary temperature gradient for a self-sufficient switching process of the Ce(III) analogue in a spatially resolved manner.

Magnetic reed biochar materials as adsorbents for aqueous copper and phenol removal

Organics and heavy metals are common pollutants in many wastewaters and water bodies. Adsorption processes by magnetic materials can rapidly remove these pollutants from water and effectively recycle adsorbent. In this study, magnetic analyzer, X-ray diffraction, Flourier transform infrared spectroscopy, and granulometry were used to characterize the synthesized magnetic reed biochar materials (ZnFe₂O₄/biochar). Influences of adsorption time, pH, temperature, initial solution concentration, and adsorption equilibrium concentration on adsorption performances were investigated for Cu²⁺ and phenol adsorption by ZnFe₂O₄/biochar. Adsorption kinetic and isotherm models were used to describe the adsorption processes. Adsorption of phenol and Cu²⁺ by ZnFe₂O₄/biochar reached saturation within 45 min and increased slightly with the increase of temperature from 15 to 45 °C. Adsorption of Cu²⁺ increased with the increase of pH, while the adsorption of phenol peaked at pH = 6. The adsorption processes fit the pseudo-second order kinetics model, and both conformed to the Langmuir model. The fitting results show that the maximum single-component adsorption capacity of phenol and Cu²⁺ by ZnFe₂O₄/biochar is 63.29 and 12.20 mg/g, and the maximum bi-component adsorption capacity reaches 40.16 and 9.48 mg/g, respectively. All the findings demonstrate that ZnFe₂O₄/biochar has good adsorption performance for phenol and Cu²⁺.

Impact of gadolinium doping into the frustrated antiferromagnetic lithium manganese oxide spinel

Cubic spinel LiMn₂O₄ (LMO) are promising electrode materials for advanced technological devices owing to their rich electrochemical properties. Here, a series of Gd³⁺-doped LiMn₂O₄ were synthesized using a simple one-step sol-gel synthesis, and a systematized study on the effect of increasing Gd³⁺ concentration on magnetic properties is conferred. The Raman and density functional theory (DFT) calculations of the synthesized materials were correlated with the magnetic properties; we observed a high coercivity value for the doped LMO compared to pristine LMO, which scales down from 0.57T to 0.14T with an increase in Gd concentration. The samples exhibited paramagnetic (at 300K) to antiferromagnetic (at 5K) transition and variation in the magnetic moment due to the replacement of Mn⁺² or Mn⁺³ ion by Gd⁺³ ion from the octahedral 16d lattice site. The observed phase transitions in the hysteresis curve below the Neel temperature (T_N) at 5K are found to be due to the superexchange mechanism.

Friction Induces Anisotropic Propulsion in Sliding Magnetic Microtriangles

In viscous fluids, motile microentities such as bacteria or artificial swimmers often display different transport modes than macroscopic ones. A current challenge in the field aims at using friction asymmetry to steer the motion of microscopic particles. Here we show that lithographically shaped magnetic microtriangles undergo a series of complex transport modes when driven by a precessing magnetic field, including a surfing-like drift close to the bottom plane. In this regime, we exploit the triangle asymmetric shape to obtain a transversal drift which is later used to transport the microtriangle in any direction along the plane. We explain this friction-induced anisotropic sliding with a minimal numerical model capable to reproduce the experimental results. Due to the flexibility offered by soft-lithographic sculpturing, our method to guide anisotropic-shaped magnetic microcomposites can be potentially extended to many other field responsive structures operating in fluid media.

Superhydrophobic modular cryogel with variable magnetic-actuated motion direction for discrete small-scale oil spill cleanup

Smart superhydrophobic sorbents are in high demand for cleaning oil spills that could endanger the aquatic ecosystem. Herein, we demonstrated the fabrication of a superhydrophobic and magnetic modular cryogel (SNS@Fe-PSC) containing three starch-based modules, namely, a superhydrophobic nano-coating, a magnetic nanocomposite insertion, and a high-strength starch/polyvinyl alcohol composite substrate. The surface chemical composition and hierarchical micro/nanostructures of this material were investigated in detail. The modular cryogel had a high water contact angle (>151°) and low sliding angle (<9°), as well as excellent water-repellent, self-cleaning, and anti-fouling properties. This material also exhibited good durability owing to its stable chemical bonding and structural support. SNS@Fe-PSC could be applied to remove oil from water effectively. Moreover, the magnetic module (saturation magnetization, 5.04 emu/g) allowed the as-obtained material to be propelled and controlled by a magnet on the surface of water. Variable magnetic-actuated motion direction could be realized by adjusting the position and amount of magnetic modules inserted to the cryogel.

Degradation of oxytetracycline by magnetic MOFs heterojunction photocatalyst with persulfate: high stability and wide range

Photocatalysis with persulfate (PS) is an effective method for the degradation of degrading organic pollutants. In this study, Fe₃O₄/MIL-101(Fe), a magnetic heterojunction photocatalyst, was produced using a hydrothermal method. The material coupled with PS exhibited excellent removal efficiency for oxytetracycline (OTC) (87.1%, 1 h). And it has a wide range of applications, with good removal efficiency for OTC concentrations of 30 to 70 mg/L and pH values of 3 to 9. •SO₄^- and •OH played a major role in the OTC removal reaction and there was an Fe(III)/Fe(II) cycle during the reaction. With excellent stability and recoverability, the OTC removal efficiency decreased by only 4.29% after four cycles, and the Fe leaching did not exceed 0.035 mg/L per cycle. This study provides significant insights into the removal of organic pollutants from water bodies.

Reversible One- to Two- to Three-Dimensional Transformation in CuII Coordination Polymer

A reversible transformation between 1D, 2D, and 3D is demonstrated for the first time in coordination polymers comprising Cu^II ions and bidentate terephthalate (BDC^2- ). 1D uniform chains were reversibly transformed into 2D layers with the construction of Cu-paddlewheels by eliminating water molecules. 2D/3D reversible transformation was achieved by removing/rebinding N,N-dimethylformamide coordinated to the paddlewheels. These dimensional transformations significantly changed chemical and physical properties such as gas sorption and magnetism. Although the uptake in open-framework 1D and 2D Cu-BDC was insignificant, pronounced absorption was observed for 3D Cu-BDC. Drastic difference in magnetic behavior is consistent with their coordination structures; uniform 1D chain of Cu^II in 1D Cu-BDC and 2D sheet based on Cu^II -paddlewheel dimers in 2D Cu-BDC. Ferromagnetic behavior observed in air-exposed 3D Cu-BDC is attributed to the 3D structure formed by the connection of 2D sheets.

The physicochemical approaches of altering growth and biochemical properties of medicinal plants in saline soils

Medicinal plants are important sources of biochemical compounds affecting human health. However, because large areas of the world are subjected to different stresses including salinity, it is important to find methods, which may control the growth and biochemical properties of medicinal plants in such conditions. Another aspect of cropping medicinal plants in saline soils is the alteration of their biochemical properties by stress. Due to the significance of planting medicinal plants in saline soils, the objective of the present review article is to investigate and analyze the physicochemical approaches including soil leaching, organic fertilization, mineral nutrition, ozonated water, magnetism, superabsorbent polymers, and zeolite, which may control the effects of salinity stress on the growth and biochemical properties (production of secondary metabolites) of medicinal plants. In our just-published review article, we investigated the biological approaches, which may affect the growth and biochemical properties of medicinal properties in saline soils. Although salinity stress may induce the production of biochemical products in medicinal plants, the use of physicochemical approaches is also recommendable for the improved growth and biochemical properties of medicinal plants in saline soils. More has yet to be indicated on the use of the physicochemical approaches, which may affect the growth and biochemical properties of medicinal plants in salt stress conditions. KEY POINTS: • Growth and physiological alteration of medicinal plants in salt stress conditions. • The physicochemical approaches of such alteration have been reviewed. • More has yet to be indicated on the approaches, which may affect such properties.

Facile route for synthesis of Fe0/Fe3C/γ-Fe2O3 carbon composite using hydrothermal carbonization of sugarcane bagasse and its use as effective adsorbent for sulfamethoxazole removal

Non-toxic mesoporous magnetic carbon composite was synthesised from hydrothermal carbonization of sugarcane bagasse with Iron (III) nitrate nonahydrate in two steps along with thermo-chemical oxidation process using sodium hydroxide. IR spectrum exposed the presence of oxygenated functional groups and FeO whereas XRD analysis revealed the availability of Fe⁰/Fe₃C/γ-Fe₂O₃ at varying intensities. SEM analysis showed the spherical shaped carbon is well encapsulated with iron particles. Textural studies showed that after thermo-chemical activation intensified the surface area on composites to about 491.474 m² g^-1 thereby, promoting improved porosity on the carbon matrix. The fabricated composite showed magnetization of 32.84 emu g^-1 and SMX adsorption capacity as 169.49 mg g^-1. Kinetics and isotherm studies revealed that removal of SMX fitted well in Pseudo-second order and Langmuir models. The mode of interaction of SMX on magnetic carbon composites with respect to different pH was studied showing that π-π electron donor interaction (EDA), hydrophobic interaction, charge assisted hydrogen bond formation were responsible for SMX removal. The selectivity nature of magnetic composite with respect to SMX was studied in the presence of multiple pollutant. Use of magnetic carbon helps in industrialising the material to high level due to their unique property in separation and recycling. Application of hydrothermal carbonization is found to be applicable for wet solid substance thereby evolving structural carbon compound.

Adsorptive removal of pollutants from water using magnesium ferrite nanoadsorbent: a promising future material for water purification

Nanoadsorbents having large specific surface area, high pore volume with tunable pore size, affordability and easy magnetic separation gained much popularity in recent time. Iron-based nanoadsorbents showed higher adsorption capacity for different pollutant removal from water among other periodic elements. Spinel ferrite nanomaterials among iron-bearing adsorbent class performed better than single iron oxide and hydroxides due to their large surface area, mesoporous pore, high pore volume and stability. This work aimed at focusing on water treatment using magnesium ferrite (MgFe₂O₄) nanomaterials. Synthesis routes, properties and pollutant adsorption were critically investigated to explore the performance of magnesium ferrite in water treatment. Structural and surface properties were greatly affected by the factors involved in different synthesis routes and iron and magnesium ratio. Complete removal of pollutants through adsorption was achieved using magnesium ferrite. Pollutant adsorption capacity of MgFe₂O₄ and its modified forms was found several folds higher than Fe₂O₃ and Fe₃O₄ nanomaterials. In addition, MgFe₂O₄ showed strong stability in water than other pure iron oxide and hydroxide. Modification with graphene oxide, activated carbon, biochar and silica was demonstrated to be beneficial for enhanced adsorption capacity. Complex formation was suggested as a dominant mechanism for pollutant adsorption. These nanomaterials could be a viable and competitive adsorbent for diverse pollutant removal from water.

Multiwavelength magnetic coding of helical luminescence in ferromagnetic 2D layered CrI3

Two-dimensional (2D) van der Waals (vdW) ferromagnets have opened new avenues for manipulating spin at the limits of single or few atomic layers, and for creating unique magneto-exciton devices through the coupling of ferromagnetic (FM) orders and excitons. However, 2D vdW ferromagnets explored so far have rarely possessed exciton behaviors; to date, FM CrI₃ have been revealed to show ligand-field photoluminescence correlated with FM ordering, but typically with a broad emission peak. Here, we report a straightforward approach to realize strong coupling of narrow helical emission and FM orders in CrI₃ through microsphere cavity. The resonant whispering-gallery modes (WGM) of SiO₂ microspheres cause strong oscillation helical emissions with a full width at half-maximum (FWHM) of ∼5 nm under continuous wave excitation. Reversible magnetic coding of helical luminescence is realized in the range of 950-1100 nm. This work enables numerous opportunities for creating magnetic encoding lasing for photonic integrated chips.

Spin fluctuations yield zT enhancement in ferromagnets

Thermal fluctuation of local magnetization intercoupled with charge carriers and phonons offers a path to enhance thermoelectric performance. Thermopower enhancement by spin fluctuations (SF) has been observed before. However, the crucial evidence for enhancing thermoelectric-figure-of-merit (zT) by SF has not been reported until now. Here we report that the SF leads to nearly 80% zT enhancement in ferromagnetic CrTe near and below T_C ∼ 335 K. The ferromagnetism is originated from the collective electronic and localized magnetic moments. The field-dependent transport properties demonstrate the profound impact of SF on the electrons and phonons. Under an external magnetic field, the enhancement in thermopower is suppressed, and the thermal conductivity is enhanced, evidencing the existence of a strong SF. The anomalous thermoelectric transport properties are analyzed based on theoretical models, and a good agreement with experimental data is found. This study contributes to the fundamental understanding of SF for designing high-performance spin-driven thermoelectrics.

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Spin-dependent thermoelectric properties are investigated

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Itinerate ferromagnetism-induced Stoner excitation favors thermoelectric transport

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Spin fluctuation contribution dominates spin-wave to the transport properties in CrTe

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Spin fluctuations boost zT by 80% near and below the transition temperature in CrTe

Aspects of high-performance and bio-acceptable magnetic nanoparticles for biomedical application

This review covers extensively the synthesis & surface modification, characterization, and application of magnetic nanoparticles. For biomedical applications, consideration should be given to factors such as design strategies, the synthesis process, coating, and surface passivation. The synthesis method regulates post-synthetic change and specific applications in vitro and in vivo imaging/diagnosis and pharmacotherapy/administration. Special insights have been provided on biodistribution, pharmacokinetics, and toxicity in a living system, which is imperative for their wider application in biology. These nanoparticles can be decorated with multiple contrast agents and thus can also be used as a probe for multi-mode imaging or double/triple imaging, for example, MRI-CT, MRI-PET. Similarly loading with different drug molecules/dye/fluorescent molecules and integration with other carriers have found application not only in locating these particles in vivo but simultaneously target drug delivery/hyperthermia inside the body. Studies are underway to collect the potential of these magnetically driven nanoparticles in various scientific fields such as particle interaction, heat conduction, imaging, and magnetism. Surely, this comprehensive data will help in the further development of advanced techniques for theranostics based on high-performance magnetic nanoparticles and will lead this research area in a new sustainable direction.

Magnetic porous biochar with high specific surface area derived from microwave-assisted hydrothermal and pyrolysis treatments of water hyacinth for Cr(Ⅵ) and tetracycline adsorption from water

Magnetic porous water hyacinth-derived biochar (MPBC_MW3) was synthesized via two-step Microwave (MW)-assisted processes. Characterization results not only testified high specific surface area (2097.50 m²/g) of the MPBC_MW3 assisted by MW-assisted pyrolysis, but also revealed its favorable magnetism derived from MW-assisted hydrothermal process. The MPBC_MW3 possessed pH-dependent monolayer adsorption capacities of 202.61 and 202.62 mg/g for Cr(VI) and TC with quick attainments of uptake equilibrium within 150 and 200 min. Moreover, the Cr(VI) and TC uptake were substantially steady under the interference from multifarious co-existing ions with slight decline after three adsorption-desorption cycles. Furthermore, the MPBC_MW3 was demonstrated to achieve excellent Cr(VI) binding primarily through complexation, electrostatic interaction, reduction and ion exchange, while presenting outstanding TC removal via pore filling, π-π stacking, hydrogen bonding force, electrostatic interaction and complexation. All these findings suggested the MPBC_MW3 synthesized by MW-assisted processes as an excellent adsorbent for purification of Cr(VI) and TC-contaminated water.