Magnetic Rods Research Articles

Catalyst‐Free, Radical Tri‐ and Difluoromethylation of Isocyanides and N‐Arylacrylamides Using Rotating Magnetic Field and Metal Rods

Comprehensive SummaryThe pursuit of sustainable and environmentally benign synthetic methods continues to challenge organic chemists. Herein, we introduce a magnetoredox system for tri‐ and difluoromethylation of isocyanides and N‐arylacrylamides using a rotating magnetic field and steel rods. This magnetoredox approach enables facile synthesis of functionalized phenanthridines and oxindoles without the need for catalysts and additives under mild conditions. Such a system potentially represents an attractive strategy for selective formation of bonds through multifaceted regulation of magnetic intensity, rotating frequency, and rod size.

Precession, nutation, and dynamic trajectory of magnetic rod in axisymmetric magnetic field

Precession and nutation in dynamical systems have been of long-standing research interest. Manifesting in systems as diverse as spinning tops to celestial bodies like planets, understanding these motions offers a window into the intricate dance of forces governing such systems. One example of a previously unexplored system exhibiting precession and nutation is that of a magnetic rod in an axisymmetric magnetic field. This project aims to study this system through qualitative, quantitative, and experimental means. A theoretical model was formulated using Newton's Second Law and the torque equation, accounting for energy dissipation. One unique aspect of this system compared to other systems exhibiting precession and nutation is the presence of the non-linear magnetic force and torque, which were modelled by considering both magnets as current-carrying cylinders. Experimentally, the dynamic trajectory and relevant degrees of freedom of the rod were measured using image binarization and ellipse fitting. This was used for a systematic investigation into how the nutation, precession and petaloid-like trajectories are affected by the number of magnets, initial angular velocity and other relevant parameters. Theoretical predictions and experimental results show a good agreement. This work has various engineering applications such as centrifuge design.

Single-Molecule Magnet Rods: Remarkably Elongated Lanthanide Phosphonate Cores with Quasilinear Hydrazones.

Large metal-phosphonate clusters typically exhibit regular polyhedral, wheel-shaped, spherical, or capsule-shaped morphologies more effectively than high-aspect ratio topologies. A system of elongated lanthanide core topologies has now been synthesized by the reaction of lanthanide 1-naphthylmethylphosphonates and four differently terminated pyrazinyl hydrazones. Four new rod-shaped dysprosium phosphonate clusters, [Dy6(O3PC11H9)4(L1)4(μ4-O)(DMF)4]·2DMF·3MeCN·3H2O (1), [Dy8(O3PC11H9)4(L2)4(μ3-O)4(CO2)4(H2O)4]·6DMF·4MeCN·3H2O (2), [Dy12Na(O3PC11H9)6(L3)6(μ3-O)2(pyr)6]·DMF·2MeCN·H2O (3), and [Dy14(O3PC11H9)12(L4)8(μ3-O)2(DMF)4(MeOH)2(H2O)4]·5DMF·2MeCN·H2O (4), were obtained. Four single-pyrazinyl hydrazones function as pentadentate bis-chelate terminal co-ligands, coordinating the periphery of dysprosium phosphonate rods. A sodium ion serves as a cation template for constructing heterobimetallic 3 by occupying the void, demonstrating the ability to reliably control cluster length by modifying the hydrazone co-ligand structure and cation template. Additionally, it was observed that the elongation of the rods has a significant directional impact on the magnetic relaxation behavior, transitioning from a one-step process in 1 to a three-step process in 2, a two-step process in 3, and finally a two-step process in 4.

Magnetic Submicron Rods for Quantitative Viscosity Imaging Using Heterodyne Holography

Magnetic Submicron Rods for Quantitative Viscosity Imaging Using Heterodyne Holography

Fabrication of a Triple-Layer Bionic Vascular Scaffold via Hybrid Electrospinning.

Tissue engineering aims to develop bionic scaffolds as alternatives to autologous vascular grafts due to their limited availability. This study introduces a novel wet-electrospinning fabrication technique to create small-diameter, uniformly aligned tubular scaffolds. By combining this innovative method with conventional electrospinning, a bionic tri-layer scaffold that mimics the zonal structure of vascular tissues is produced. The inner and outer layers consist of PCL/Gelatin and PCL/PLGA fibers, respectively, while the middle layer is crafted using PCL through Wet Vertical Magnetic Rod Electrospinning (WVMRE). The scaffold's morphology is analyzed using Scanning Electron Microscopy (SEM) to confirm its bionic structure. The mechanical properties, degradation profile, wettability, and biocompatibility of the scaffold are also characterized. To enhance hemocompatibility, the scaffold is crosslinked with heparin. The results demonstrate sufficient mechanical properties, good wettability of the inner layer, proper degradability of the inner and middle layers, and overall good biocompatibility. In conclusion, this study successfully develops a small-diameter tri-layer tubular scaffold that meets the required specifications.

A magnet foreign body in the vermiform process in a child aged two years and eight months

BACKGROUND: Foreign bodies in the gastrointestinal tract is a fairly common pathology in pediatric surgery. The proportion of all cases is about 80%; in 20% of cases, foreign bodies can stuck in the physiological colon narrowings and in 0.005% — in the appendix. It is thought that magnetic foreign bodies pose a danger, if they are two or more because they can be attracted to each other at different parts of the gastrointestinal tract. A foreign body can get into the vermiform process, if its mass exceeds the mass of caecum content. Under the gravity mechanism, the foreign body penetrates into the dilated appendix lumen, but lumen peristalsis may not be strong enough to push it back into the large intestine. Swallowed foreign bodies may be asymptomatic in the vermiform process, and can manifest clinically as the inflammation either after few hours or after many years. CLINICAL CASE DESCRIPTION: In patient X., aged 2 years and 8 months, a magnet foreign body (a piece of magnetic pen) got into the vermiform process. The independent discharge of this object was under control, but no results. Patient's general state was satisfactory. No pathologies were observed in organs and systems. After a series of X-ray examinations of the abdominal organs, suspicion appeared that this foreign body was in the appendix. Diagnostic laparoscopy with intraoperative radiography and then laparoscopic appendectomy were performed. Macropreparation: unchanged vermiform process 6 cm long. The appendix lumen was opened, a foreign body was found — a magnetic rod with size 0.5 cm x 0.2 cm. CONCLUSION: The postoperative period was uneventful. The child was discharged from the hospital in the recovering state after the performed surgical intervention — an elective laparoscopic appendectomy.

Application of bioinspired geomagnetic sensor measurements and geomagnetic map modeling based on neural networks in simulated navigation

A geomagnetic field is a vector field in which the strength and direction are related to geographical location. Geomagnetic navigation technology, which uses collected geomagnetic field information to achieve positioning and navigation, has the advantages of reliability, stability, accuracy, and concealment. With the deepening research on geomagnetic navigation, bioinspired geomagnetic navigation technology has also been developed, which mainly studies and imitates the magnetic sensing mechanism and navigation behavior of animals, providing new research ideas for geomagnetic navigation technology. The magnetic particle hypothesis and free radical pair hypothesis are two mainstream mechanisms of biological sensing using the geomagnetic field, and studies have shown that these two mechanisms may be coupled within organisms. In this study, we propose a bioinspired weak magnetic vector (BWMV) sensor based on the joint sensing mechanism of magnetic particles and free radicals. It consists of a magnetic rod made of soft magnetic material and a tunnel magnetoresistance (TMR) sensor array. A magnetic rod was used to simulate magnetic particles to convert magnetic field angle information into magnetic field intensity distribution information, and the TMR sensor array was used to simulate the perception of the magnetic field distribution by free radicals. In addition, artificial neural networks (ANNs) were used for BWMV sensors to obtain the mapping relationship between the magnetic field distribution and parameters, which can be used for geomagnetic navigation. To verify the navigation effect of the BWMV sensor in the laboratory, a simulated geomagnetic navigation device was built, and the high-precision mapping relationship from geomagnetic parameters to latitude and longitude information of the selected navigation area was obtained through another ANN. Finally, the effectiveness of the BWMV sensor based on ANNs for geomagnetic navigation is verified using simulated navigation experiments.

Preparation and photocatalytic activity of CoFe2O4 nanoparticle modified rod-like Mn0.3Cd0.7S photocatalysts with S-scheme heterojunction

With the continuous progress of photocatalytic technology in environmental pollution control, the recovery of photocatalysts has gradually become a hot topic of concern. To solve this problem, a magnetically recoverable rod-shaped CoFe2O4/Mn0.3Cd0.7S with S-scheme heterojunction photocatalyst was successfully constructed. The phase composition, morphology, light absorption, and surface chemical environment of the samples were measured. The photocatalytic degradation rate of tetracycline by CoFe2O4/Mn0.3Cd0.7S is higher than that either of CoFe2O4 and Mn0.3Cd0.7S. The degradation efficiency of 1%CoFe2O4/Mn0.3Cd0.7S showed the best performance of 82.1% within 60 min. The rate constant for first-order kinetics of 1%CoFe2O4/Mn0.3Cd0.7S was about 1.72 times that of pure Mn0.3Cd0.7S. It was found that the enhanced photoactivity of the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was due to the wider absorption range of visible light and the improved inhibition of electron and hole recombination. It is also found that the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst has excellent magnetic recovery ability under the external magnetic field. The photostability of as-prepared CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was studied, and a reasonable S-scheme electron-hole transfer mechanism was proposed according to the band structure. These advances provide a new way to improve the photoactivity of magnetic recyclable photocatalysts, and the synthetic magnetic recyclable rod CoFe2O4/Mn0.3Cd0.7S has a potential application prospect in the degradation of water pollutants.

Enhanced tribocatalytic degradation performance of organic pollutants by Cu1.8S/CuCo2S4 p-n junction

Tribocatalysis research, leveraging the triboelectric effect, presents significant potential for environmental water pollution control. However, there is a notable scarcity of studies pertaining to tribocatalysis involving heterojunctions, particularly in the context of p-n junction tribocatalysis. In this study, we employed a one-step solvothermal method to synthesize a Cu1.8S/CuCo2S4 p-n junction composite catalyst. Subsequently, we explored the tribocatalytic degradation performance of organic pollutants facilitated by the Cu1.8S/CuCo2S4 catalyst. The findings reveal that, under simple magnetic stirring conditions, the degradation rates achieved by the Cu1.8S/CuCo2S4 catalyst for tetracycline (TC), methylene blue (MB), and methyl orange (MO) are remarkably high, reaching 99.9 %, 99.7 %, and 94.0 %, respectively. This underscores the broad applicability of the Cu1.8S/CuCo2S4 catalyst for the tribocatalytic degradation of diverse organic pollutants. Experimental evidence establishes that friction occurring between the polytetrafluoroethylene (PTFE) magnet rod, the beaker, and the catalyst induces charge transfer at their interfaces, generating highly oxidized active species that effectively decompose pollutants. Through free radical capture and electron spin resonance (ESR) tests, it was empirically determined and validated that the principal active species involved in tribocatalytic degradation are holes (h+) and superoxide radicals (O2–). Incorporating insights from the experimental characterization of p-n junctions and density functional theory (DFT) theoretical calculations, we propose a plausible tribocatalytic mechanism for Cu1.8S/CuCo2S4. This research not only contributes novel findings but also serves as a reference for the exploration of innovative heterojunction tribocatalysts.

Growth Arrest in Type IV Osteogenesis Imperfecta After Fassier-Duval Rod Insertion Treated by a Lengthening Magnetic Intramedullary Nail: A Case Report.

A child with Type IV Osteogenesis Imperfecta (OI) sustained a growth arrest of the distal femur after fixation of a left femur fracture with a Fassier-Duval expanding rod at 3 years old. Despite bar resection with fat interposition, the discrepancy progressed to 7.5 cm at maturity. Because the femur had grown to a sufficient diameter, he underwent successful lengthening with a magnetic intramedullary rod. Although it is a potential complication, growth arrest has not been reported in association with placement of an expanding nail in a child with osteogenesis imperfecta. This case illustrates this rare complication and treatment using a magnetic intramedullary rod.

Novel electrochemical biosensor for breast cancer detection, based on a nanocomposite of carbon nanofiber, metal–organic framework, and magnetic graphene oxide

In this study, we present the newly developed a novel microRNA biosensor based on magnetic rod carbon paste electrodes for breast cancer detection by using a relatively new MOF structure as a substrate. The major goal of manufacturing biosensors, suitable for clinical diagnostics, is to measure very low amount of microRNA 155 in complex environments. Therefore, we used a combination of different materials, including carbon nanofibers, CuBTC-AIA (CuMOF), and Fe@rGO, to improve the electrode surface-to-volume ratio and facilitate the electron transfer process. In this method, 1-pyrenebutyric acid N-hydroxysuccinimide ester was used to bind the microRNAs to the electrode surface. The hybridization process on the modified electrode surface was investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry across the potential range, in which the accumulated hematoxylin was electroactive. Under optimal conditions, a very low detection limit of 0.08 fM and an adequate dynamic range of 0.2 fM–500 pM were achieved. The fabricated sensor was reported to be reproducible and selective when tested using different types of mismatched target sequences. And finally, the real human serum samples were used to confirm the capability of the nanobiosensor to detect microRNA 155 without any significant interference from other molecules and components.

Heterogeneous Dynamics of Sheared Particle-Laden Fluid Interfaces with Janus Particle Doping.

The formation of particle clusters can substantially modify the dynamics and mechanical properties of suspensions in both two and three dimensions. While it has been well established that large network-spanning clusters increase the rigidity of particle systems, it is still unclear how the presence of localized nonpercolating clusters affects the dynamics and mechanical properties of particle suspensions. Here, we introduce self-assembled localized particle clusters at a fluid-fluid interface by mixing a fraction of Janus particles in a monolayer of homogeneous colloids. Each Janus particle binds to a few nearby homogeneous colloids, resulting in numerous small clusters uniformly distributed across the interface. Using a custom magnetic rod interfacial stress rheometer, we apply linear oscillatory shear to the particle-laden fluid interface. By analyzing the local affine deformation of particles from optical microscopy, we show that particles in localized clusters experience substantially lower shear-induced stretching than their neighbors outside clusters. We hypothesize that such heterogeneous dynamics induced by particle clusters increase the effective surface coverage of particles, which in turn enhances the shear moduli of the interface, as confirmed by direct interfacial rheological measurements. Our study illustrates the microscopic dynamics of small clusters in a shear flow and reveals their profound effects on the macroscopic rheology of particle-laden fluid interfaces. Our findings open an avenue for designing interfacial materials with improved mechanical properties via the control of formation of localized particle clusters.

Effect of Magnetic Field on the Flame Characteristics of Droplet Combustion of Coconut and Palm Oil

Experimental has been conducted on the effects of variations in the direction of the magnetic fields on flames characteristic of droplets combustion of coconut and palm oils. Two variations of the directions magnetic field N-N and S-N were used in this experiment by placing droplets of vegetable oils on the type K thermocouple between two permanent magnet rods. High-speed camera (120 frame per second) recorded the flames up to extinguished. The result showed that S-N magnetic fields affected on shorter burning time of coconut and palm oil, respectively 670 ms and 871 ms, with the highest temperature of 816.25 oC and 778 oC. The flame height produced by the S-N magnetic field in coconut oil is 34.36 mm shorter, ignitions delay time for all oils has faster than the N-N magnetic field. The strong magnetic field direction increases the oxygen concentrations and fuel molecules around the reaction zone, causing shorter combustion. This combustion produces different flame evolution, shape, height, temperature, and ignition delay times. Keywords: Flames evolution, Flames height, Flames temperature, Ignition delay, Vegetable oils.

THE EXPERIMENTAL OF IMPACT OF ADDITIONAL MAGNETIC FIELDS AND NITROGEN PRESSURE ON OLIVE OIL DROPLET COMBUSTION

This experiment studies the impact of a magnetic field of attraction and various nitrogen pressures in the combustion chamber on the characteristics of the flame. To replace depleted fossil fuels, the usage of vegetable oil is crucial. This research aims to probe the droplet combustion of olive oil on evolution, temperature, height, and ignition delay. The camera's high speed is 120 frames per second front-facing camera records the process from the start flamed until it has extinguished. A droplet of olive oil is placed on a type K thermocouple between two magnet rods in a nitrogen-pressurized chamber—three variations of nitrogen pressure in the combustion chamber, which included 0.5, 1, and 1.5 bar. The results found that the nitrogen pressure of 0.5 bar led to evolution, and the flame stability was more stable. Moreover, the highest temperature and flame delay was shorter than the pressures of 1 bar and 1.5 bar. At a pressure of 0.5 bar, the flame evolution was 1200 milliseconds, the maximum temperature was 741 °C, and the ignition delay of 4506 milliseconds was shorter than the other two pressures. That occurred due to high nitrogen pressure inhibiting the collision reaction of the olive oil fuel vapor with air. Meanwhile, adding an attraction magnetic field can centralize oxygen and fuel molecules in the area of the reaction zone, resulting in rapid combustion and a shorter flame delay change.

Spatial Confinement of Single-Drop System to Enhance Aggregation-Induced Emission for Detection of MicroRNAs

Due to high incidence, poor prognosis, and easy transformation into pancreatic cancer (PC) with high mortality, early diagnosis and prevention of acute pancreatitis (AP) have become significant research focuses. In this work, we proposed a magnetic single-drop microextraction (SDME) system with spatial confinement to enhance the aggregation-induced emission (AIE) effect for simultaneous fluorescence detection of miRNA-155 (associated with AP) and miRNA-196a (associated with PC). The target miRNAs were selectively recognized by the hairpin probe and triggered the DNA amplification reaction; then, the DNA strands with two independent probes of G-quadruplex/TAIN and Cy5 were constructed on the surfaces of the magnetic beads. The SDME process, in which a drop containing the fluorescence probes was formed at the tip of the magnetic microextraction rod rapidly within 10 s, was performed by magnetic extraction. In this way, G-quadruplex/TAIN was enriched owing to the spatial confinement of the single-drop system, and the fluorescence signal given off (by G-quadruplex/TAIN) was highly enhanced (AIE effect). This was detected directly by fluorescence spectrophotometry. The approach achieved low limits of detection of 2.1 aM for miRNA-196a and 8.1 aM for miRNA-155 and wide linear ranges from 10 aM to 10 nM for miRNA-196a and from 25 aM to 10 nM for miRNA-155. This novel method was applied to the fluorescence detection of miRNAs in human serum samples. High relative recoveries from 95.6% to 104.8% were obtained.

Encyclopedia of emergent particles in 528 magnetic layer groups and 394 magnetic rod groups

We present a systematic classification of emergent particles in all 528 magnetic layer groups and 394 magnetic rod groups, which describe two-dimensional and one-dimensional crystals, respectively. Our approach is via constructing a correspondence between a given magnetic layer/rod group and one of the magnetic space groups, such that all irreducible representations of the layer/rod group can be derived from those of the corresponding space group. Based on these group representations, we explicitly construct the effective models for possible band degeneracies and identify all emergent particles, including both spinless and spinful cases. We find that there are six kinds of particles protected by magnetic layer groups and three kinds by magnetic rod groups. Our work provides a useful reference for the search and design of emergent particles in lower dimensional crystals.

Passive topological waveguide controlled by the boundary of the patterned area of external magnetic field with the hybrid quantum Hall and valley Hall effects

Topological waveguides with arbitrary pathway are desirable for many applications. In this paper we construct a triangular compound lattice consisting of magnetic dielectric rods. By breaking the space symmetry and the time-reversal symmetry, the structure generates topological edge states (TESs) from the hybrid quantum Hall effects and valley Hall effects. This topological edge waveguide pathway can be arbitrary arranged just by the external magnetic field. The hybrid topological phase provides a new and ultraflexible way to the reconfiguration of the TESs.

The influence of various preheating and direction of magnetic field on combustion characteristics of palm oil droplets for boiler combustion in power generation system

Research has been carried out on the effect of various preheating and the direction of the magnetic field on the flame characteristics of droplet combustion. This study is important to substitute fuel from fossils with vegetable oil that is environment friendly. The variations of the magnetic field are south-south pole, north-north pole, south-north pole, north-south pole, and without. A drop of palm oil is placed on a type K thermocouple between two magnetic rods. The high-speed camera of 120 fps from the front recorded the flame from the start until it went out. The researcher found out the influence of various preheating in palm oil and the magnetic characteristics and behavior of the flame. The direction of the north-south magnetic field had a higher magnetic field strength, caused the droplet combustion to increases resulting in a wider flame but a lower and more stable height compared to other magnetic field directions. The speed of combustion affected by the magnetic field intensity which resulted the flow rate of O2, therefore the combustion speed happened quickly because between O2 and the fuel molecules easily react and were more flammable. The strength of the magnetic field increased oxygen concentration and fuel molecule around the reaction zone causing a short burning, resulting in a change delay time the shorter but the flame temperature increased. Stability, shape, temperature, height, delay time and combustion duration were highly valuable to design an efficient heat generator industry with the addition of magnet field. This study provides insight into the influence of magnetic field direction in magnetic field intensity on droplet combustion characteristics for boiler combustion in the power generation system

Ultrawideband axion search using a Faraday haloscope

Dark matter is a major constituent of our Universe and the axion is a prime candidate. In this article, it is shown that by exploiting the axion induced magnetization in a magnetic rod and the Faraday effect, axions in the mass range $500--5000\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{eV}$, a part of which ($>3500\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{eV}$) is currently inaccessible to experiments, can be searched for using the same experimental setup in a year using the existing technologies. The magnetic rod is placed inside a high-finesse optical cavity, which by confining the probe light inside it increases the interaction time and thus enhances the Faraday effect. This rotates the plane of polarization of the probe light sufficiently and produces a robust signal. Axions of different mass are selected using a dc magnetic field. Detection is carried out by counting photons in the optical domain using a readily available and high quantum efficiency ($\ensuremath{\approx}1$) photon counter in a noise-free environment. An optical interferometric scheme that could provide spectroscopic information about the axion to be searched is also proposed.

A Recursive Approach for Magnetic Field Estimation in Spacecraft Magnetic Attitude Control

This paper is concerned with magnetic attitude control of spacecraft. The operation of the magnetic actuators is usually on a duty cycle; during the off times in this duty cycle the magnetometers are used to measure the magnetic field around the spacecraft. This alternate operation of magnetic actuators and sensors avoids the noise effect on the magnetometers coming from the magnetic actuators. This alternate operation results in longer maneuver times. This paper presents an estimation approach for the magnetic field, as well as the spacecraft attitude, that increases the duty cycle of the magnetic rods while reducing the rate of collecting the magnetometer data. A modified Multiplicative Extended Kalman Filter (MEKF) is used in the proposed approach. A relatively simple and fast dynamic model is developed for use in the MEKF. Monte Carlo simulations presented in this paper show that the proposed approach results in less maneuver time, and less power consumption by the magnetic rods when compared to a standard magnetic control approach. The magnetic field estimation process is verified using data collected from the CASSIOPE spacecraft using its telemetry system and the results are presented.