Magnetic Carrier Research Articles

PH-responsive magnetic biocompatible chitosan-based nanocomposite carrier for ciprofloxacin release

The pH-sensitive and magnetic-triggered release ensures the effective delivery of drugs. Chitosan carries amine pendants that encourage the fabrication of pH-responsive carriers. Montmorillonite (MMt), an attractive nano-clay in drug delivery possessing high encapsulation properties, was magnetized through the co-precipitation of Fe3+/Fe2+ ions. The study aimed to integrate the magnetic montmorillonite (mMMt) into the chitosan matrix and crosslinked by citric acid (CA) to achieve the nanocomposite carrier with double-responsive features for effective drug delivery. The release evaluation revealed that coating the mMMt with CA-crosslinked chitosan prevented the burst release of Ciprofluxcacin (Cip). The nanocomposite showed a high sustained release, and the release rate in the neutral environment (pH 7.4) was remarkably higher than in acidic media (pH 5.8). The new nanocomposite carrier showed high encapsulation efficiency to Cip (about 98 %). The study was developed by investigating external magnetic effects on the release rate, which lead to an increase in the release rate. The kinetics studies confirmed the diffusion mechanism for Cip release in all experimental media. The Cip-loaded nanocomposite carriers showed antibacterial activity against E. coli and S. aureus.

A new strategy for magnetic immobilized phospholipase A1 and its application in soybean oil degumming: Multipoint covalent binding

In order to achieve better degumming of crude soybean oil and reduce the phosphorus content in oil, a method of multipoint immobilized phospholipase A1 (PLA1) was proposed for degumming. PLA1 with a high enzymatic load and good stability was magnetically immobilized on a modified aldehyde-rich chitosan carrier by changing the pH. The aldehyde content of the activated carrier reached 288 μmol/g. The optimal conditions of the magnetic carrier and PLA1 multi-point covalent binding were as follows: PLA1 additive amount 6000 U/ml, group ratio 7:1, reaction at 50 °C for 3.0 h. According to the characterization analysis, PLA1 was essentially spherical with good dispersion, the particle size was 83 nm, and the XRD pattern was similar to the conventional one. After functional group analysis, spectral peaks, such as CO and Fe–O, appeared, which proved that PLA1 was successfully fixed on the carrier with a saturation magnetization of 23.68 emu/g. The optimum temperature of covalent and multipoint immobilized PLA1 was 60 °C, with an optimum pH of 7.0 and 6.5 and an enzyme loading of 115 and 128 mg/g, respectively. The phosphorus content was 35.09 mg/kg by multipoint immobilized PLA1. After eight cycles of repeated use, the relative activity of the immobilized PLA1 was still more than 80%.

Competitive immunoassay using enzyme-regulated Fe3O4@COF/Fe3+ fluorescence probe for natural chloramphenicol detection

Accurate and sensitive detection of chloramphenicol (CAP) in natural samples is essential for ensuring human health. Herein, an enzyme-regulated fluorescence sensor using Fe3O4@COF/Fe3+ probe, is developed for CAP determination. Fe3O4@COF, synthesized via hydrothermal method, exhibits dual functions as a magnetic carrier and signal probe. Bovine serum albumin conjugated-chloramphenicol, adsorbed on the surface of Fe3O4@COF, competes with CAP for antibody binding. The antibody interacts with alkaline phosphatase via the biotin-streptavidin system. Meanwhile, ascorbic acid, produced from the enzyme-catalyzed reaction dominated by alkaline phosphatase, effectively restores the fluorescence of Fe3O4@COF that is quenched by Fe3+. After experimental verification and gradual optimization, a logarithmic linear relationship between CAP concentration and fluorescence intensity is established in the range of 2 × 10−4∼10 μg mL−1, with a good limit of detection (9.2 × 10−5 μg mL−1). Proposed method exhibits excellent stability (15 days) and reusability (8 cycles), providing a sensitive and reliable method for accurate CAP detection. The readouts show good agreement with HPLC and recoveries during laboratory and natural CAP analysis.

Preferred Orientations of Magnetic Minerals Inferred from Magnetic Fabrics of Hantangang Quaternary Basalts

This paper presents a comprehensive analysis of the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data from Quaternary basalt outcrops along the Hantangang River, Korea. A total of 554 samples were collected from 20 sites, representing three distinct units, Unit I, Unit II, and Unit III. Paleomagnetic data reveal a difference in the timing of eruptions between Units I and II, suggesting distinct periods by volcanic episodes. The mineral magnetic analysis identified titanomagnetite as the dominant magnetic carrier in the samples. AMS results indicated weak anisotropy and scattered AMS directions, indicating a low degree of preferred orientation of grains within the basalt rocks. The inverse AMS fabrics observed at specific sites are attributed to single-domain (SD) grains. Comparing the AMS data with the anisotropy of anhysteretic remanent magnetization (AARM) data, three distinct types of magnetic fabrics (normal, intermediate, and inverse) were discerned. The magnetic fabric was utilized to ascertain the flow direction based on the findings obtained from the AMS results. The findings suggest that the Quaternary basalts in this study’s area were primarily confined to the Hantangang River channel and its immediate vicinity during lava flow. However, distinct flow patterns are observed in the southwestern region, implying the presence of unknown volcanic sources.

Anisotropy of magnetic susceptibility impressed during rock magnetic procedures (AF, IRM) and information on the domain state of the magnetic carriers

We present and interpret anisotropy of magnetic susceptibility (AMS) fabrics in various rocks, focusing on the effects of Alternating Field (AF) demagnetization and Isothermal Remanent Magnetization (IRM). Our findings reveal that AMS in samples from intrusive rocks with large multidomain magnetite grains is minimally affected by IRM or static AF demagnetization. In nearly isotropic volcanic rocks with titanomagnetite pseudo single domain (PSD) carriers, AMS fabrics caused by static AF demagnetization are easily identifiable, with the most prominent effect being a well-defined AMS lineation (up to 1.04) in the direction of the applied AF demagnetization. Conversely, in samples from rapidly cooled volcanic rocks with titanomagnetite of smaller magnetic grain size, an AMS foliation (∼1.02) is observed orthogonal to the direction of the applied AF field, instead of a lineation. In such samples, an IRM produces a much larger AMS foliation up to 1.3 orthogonal to the IRM. The IRM-impressed AMS is also particularly strong in metamorphic rocks in the greenschist facies with either titano-hematite or pyrrhotite magnetic carriers. Samples with the largest IRM-impressed fabric have very high Mrs/Ms ratio (>∼0.4). Mrs/Ms ratios above 0.5 may indicate the contribution of SD magnetic grains with multiaxial anisotropy. As the apparent multiaxial anisotropy is especially observed in volcanic rocks with micron size dendrites of titanomagnetites, the complex shape of the magnetic particles and their chemical composition likely play a key role in IRM-impressed AMS. AMS fabric in volcanic rocks should not be measured after static AF demagnetization. Tumbling AF demagnetization does not alter significantly the initial magnetic fabric and could be safely used in rocks with strong magnetization related to lightning possibly recording an IRM impressed AMS.

Formulation and Characterization of Magnetically Responsive Mesalamine Microspheres for Colon Targeting

Background: Magnetically Responsive Mesalamine Microspheres is an effective strategy for localized drug delivery only at the target site for the treatment of Irritable Bowel Diseases and thereby minimizing the dose and drug induced toxicity. Objective: The main objective of the study is to localize the drug only at the target site thereby minimizing the dose. Result and Discussion: 1. The aim of present study was to formulate Magnetically Responsive Mesalamine Microspheres by solvent evaporation method using biodegradable polymers Chitosan and Pectin and carry out the various pharmaceutical and magnetic characterizations, to study the effect of polymer type on in-vitro drug release and preclinical in-vitro screening studies such as in- vitro release studies using microflora activated system and in-vitro anti-inflammatory activity. 2. Chemical compatibility study was performed using FTIR spectroscopy. FTIR spectroscopy studies indicated that the Mesalamine is compatible with polymers. The spectra showed no changes in the major peaks thus confirming no interactions between drug and polymers. 3. Calibration curves of Mesalamine was constructed in Phosphate Buffer Saline pH7. 4. Magnetite (Fe3O4) (used as magnetic carrier) was chemically synthesized using precipitation method.5. In the present study, 3 formulations were prepared in total by using Chitosan and Pectin as polymer in different ratios (1:1,1:2 and 1:3) of each polymer and combination of two polymers. Also, the effect of polymer type was studied. Conclusion: It can be concluded that the Magnetically Responsive Mesalamine Microspheres offer a localized drug delivery only at the target site by the combined effect of physical approach (utilizing the principle of magnetic targeting with an intention to produce a depot near the target organ) and biochemical approach (using biodegradable polymers chitosan and pectin for drug release in a controlled manner). By producing a depot near the target organ, unwanted distribution of drug to non-target organ can be avoided.

Magnetic structure, physical field coupling effect and carrier mobility of nanostructures based on armchair-edged phosphorene nanoribbons

Using the first-principles calculation based on the density-functional theory, we study the magnetic properties, carrier mobility and physical field coupling effects on armchair-edged phosphorene nanoribbons terminated with Mn and F atoms (APNR-Mn-F2). The results show that such a structure is an excellent bipolar spin semiconductors with a very high Curie temperature, near room temperature. There exists a significant difference in electron and hole mobility. The hole mobility is up to 106 cm2/V⋅s, which is much higher than that of the original phosphorene. In particular, the electronic properties of the ribbon can be effectively adjusted by applying strain and electric field. The applied electric field can lead to a reversible modulation on magnetic moment and electronic phase transition among magnetic semiconducting, half-metallic and magnetic metallic states. This tunable electronic property expands the applications of nanoribbons in nanoelectronics and optoelectronics.

Effective removal of cesium by ammonium molybdophosphate–polyethylene glycol magnetic nanoparticles

This study synthesizes a new adsorbent composite for the removal of Cs ions from waste effluents. The adsorbent is composed of polyethylene glycol-decorated ammonium molybdophosphate magnetic Fe3O4 nanoparticles (PEG–AMP MNs) and is prepared via coprecipitation by grafting ammonium phosphomolybdate onto the surface of Fe3O4 and coprecipitation with polyethylene glycol. The physical and chemical structure of the PEG–AMP MNs was investigated using various spectroscopic and analytical techniques, revealing that Fe3O4 was tightly bound to the AMP particles and that the composites exhibited superparamagnetic behavior. The Cs+ adsorption behavior of the adsorbent was investigated in a wide range of pH values and temperatures, using multiple Cs+ contact times and initial Cs+ concentration, and with interference from additional ionic species. The adsorbent achieved 99.8% removal of Cs+ in the solution pH range of 1–12 and maintained its stability after adsorption. Interfering ions had little effect on the amount of Cs+ adsorbed. The experimental data were fitted using Langmuir, Freundlich, Redlich-Peterson and Sips isotherms pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption data fitted well with pseudo-second-order kinetics and the Langmuir isotherm model, with a maximum adsorption capacity of 53.89 mg g−1 and equilibrium reached within 20 min. Thermodynamic experiments showed the adsorption process to be inherently endothermic. The mechanism of Cs+ adsorption by PEG–AMP MNs is proposed to primarily be a combination of weak electrostatic attraction and ion exchange between NH4+ and Cs+. More importantly, the encapsulation of a magnetic carrier allows for the efficient separation and recovery of Cs+ after adsorption.

Magnetic molecularly-imprinted microspheres with a core-shell structure for the extraction of catalpol from both Rehmannia glutinosa Libosch and biological samples

We report on the successful development of a magnetic molecularly imprinted polymer (MMIP) for the separation and detection of catalpol in Rehmannia glutinosa extract and biological samples. Catalpol was used as the template molecule for the MMIPs, which were synthesized using the reverse prediction approach and differential UV–visible spectra to optimize the synthesis conditions. The resulting MMIPs were characterized using techniques including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry, which confirmed their excellent nuclear shell construction and simple rapid magnetic separation.Static and dynamic adsorption experiments were performed to assess the sensitivity, repeatability, and adsorption capacity of the MMIPs. Adsorption capacity was found to be high (59.09 µg/mg). The MMIPs also exhibited strong identification specificity for catalpol analogs (IF = 2.41). Magnetic solid phase extraction (MSPE) was optimized to establish an MSPE-HPLC approach based on the MMIPs. Under ideal conditions, the new method showed excellent determination coefficient (R2 > 0.99) in the ranges of 0.1–1.0 mg/mL and 0.03–0.18 mg/mL for R. glutinosa extract and biological material, respectively, with limits of detection of 5.4 ng/mL and 1.7 ng/mL.The novelty of this research lies in the preparation of magnetic surface MMIPs using a magnetic carrier. These MMIPs exhibit excellent magnetic properties and possess specific adsorption capability for catalpol, enabling rapid separation. They offer advantages such as low cost, high specificity, chemical stability, physical robustness, and recyclability (97.09%–106.53%, 91.32%–100.99%). The application of these polymers in the pretreatment method for determining the catalpol content in R. glutinosa extract and biological samples enhances the extraction efficiency and detection accuracy for catalpol. It eliminates interference and influences from other components in catalpol determination while exhibiting high sensitivity, good enrichment effects, excellent reusability, and a high recovery rate.

Substituent Effect to Fine-Tune Energy Levels of Atom-Precise [MoOS3]2- Modified Cu(I) Thiolate Clusters Boosting Recyclable Photocatalysis.

The propulsion of photocatalytic hydrogen (H2) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS3]2- unit is introduced into the Cu(I) clusters to form a series of atomically-precise Mo(VI)-Cu(I) bimetallic clusters of [Cu6(MoOS3)2(C6H5(CH2)S)2(P(C6H4-R)3)4]·xCH3CN (R = H, CH3, or F), which show high photocatalytic H2 evolution activities and excellent stability. By electron push-pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these Mo(VI)-Cu(I) clusters can be finely tuned, promoting the resultant visible-light-driven H2 evolution performance. Furthermore, Mo(VI)-Cu(I) clusters loaded onto the surface of magnetic Fe3O4 carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster-based catalyst. This work not only highlights a competitively universal approach on the design of high-efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.

Substituent Effect to Fine‐Tune Energy Levels of Atom‐Precise [MoOS3]2− Modified Copper(I) Thiolate Clusters Boosting Recyclable Photocatalysis

AbstractThe propulsion of photocatalytic hydrogen (H2) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS3]2− unit is introduced into the CuI clusters to form a series of atomically‐precise MoVI−CuI bimetallic clusters of [Cu6(MoOS3)2(C6H5(CH2)S)2(P(C6H4−R)3)4] ⋅ xCH3CN (R=H, CH3, or F), which show high photocatalytic H2 evolution activities and excellent stability. By electron push‐pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these MoVI−CuI clusters can be finely tuned, promoting the resultant visible‐light‐driven H2 evolution performance. Furthermore, MoVI−CuI clusters loaded onto the surface of magnetic Fe3O4 carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster‐based catalyst. This work not only highlights a competitively universal approach on the design of high‐efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.

On the Emplacement of the Impact Melt at the Dhala Impact Structure, India

AbstractWe investigate the magnetic fabrics and magnetic mineralogy of the impact melt rock at the Dhala impact structure to understand its emplacement mechanism. Pseudo‐single domains of Ti‐poor magnetite and Ti‐hematite are the prime magnetic carriers in the impact melt rock. The magnetic foliations show a range of dip amounts. The overall trend of the magnetic foliation of the impact melt rock draws a resemblance with the flood basalts or lava flows. A well‐developed magnetic lineation (K1) indicates the strong alignment of Ti‐poor magnetite grains. Therefore, the magnetic carriers may have crystallized and aligned themselves along the flow direction before the emplacement. It may be possible that after the crystallization of the magnetic carriers, the impact melt moved in a semi‐molten state similar to lava flows with temperatures below c. 1,500°C, which is the melting point of Ti‐magnetite and was emplaced as crater‐fill deposits. Among the three principal magnetic susceptibility axes, K1 aligns best with the mesoscopic flow indicators. K1 of individual specimens' trends between NW and SW, while the mean K1 at all the sites trends westward. Thus, at the studied sites, the impact melt flow was dominantly eastward. In the sites located to the NW and W, the eastward flow could be due to gravity‐driven crater inward flow toward the center. At site IM2, which is located to E, the eastward flow of the impact melt is possibly due to crater outward excavation flow.

A brushed magnetic microbeads carrier with host-guest structures for enhancing bio-detection performance in beads-based flow cytometry

Here we report a brushed magnetic microbeads (BMBs) carrier with host-guest structures for enhancing bio-detection performance in beads-based flow cytometry (FCM). The micro-sized MBs are employed as host spheres and the nano-sized spherical polyelectrolyte brushes (SPBs) are utilized as guest particles to achieve the covalent assembly of SPBs on MBs (that is BMBs). Our proposed BMBs carrier exhibits a remarkable signal to noise improvement of approximately 8–9 times in beads-based immunoassay on FCM compared to conventional MBs via preserving capture antibodies’ activity and reducing detection antibodies’ nonspecific adsorption. This study demonstrates the promising potential of our developed BMBs carrier for beads-based flow cytometry.

Possible evidence for geomagnetic intensity anomaly around 5500 BP from archaeomagnetic analyses of San Jacinto pottery, Caribbean Colombia

San Jacinto archaeological site in Northern Colombia hosts America's oldest pottery, radiometrically dated between 5940 ± 60 BP and 5190 ± 40 BP. Eleven ceramic fragments were subjected to detailed archaeomagnetic and archaeointensity investigation. Alternating field and thermal demagnetization, as well as magnetic mineralogy experiments, were carried out before double heating paleointensity determination to select the most suitable samples. Magnetic susceptibility vs. temperature curves revealed that magnetite and hematite grains are the main carriers of the thermoremanent magnetization. However, the contribution of hematite in total remanence seems to be negligible. Thirty-six samples corresponding to six pottery fragments were selected for Thellier-type paleointensity determinations. Mean intensity values range from 50.7 ± 4.7 to 65.3 ± 11.9 μT while virtual Axial Dipole Moments vary from 12.6 ± 1.2 to 16.2 ± 2.9 × 1022 Am2, indicating high geomagnetic field strength compared to values predicted by global geomagnetic models. This represents the first evidence of relatively high archaeointesities before 1000 BC. Similar or even higher geomagnetic strengths are observed in the Levant around 1100–800 BC and SW Pacific Region at 1450 AD. The actual cause of such anomalously high intensity, often attributed to the processes in the vicinity of the Core-Mantle Boundary, is still not fully understood.

Evaluation of the alternating magnetic field (AMF) influence in catalytic activities of enzymes immobilized into magnetic graphene oxide: A new approach

The conventional methods of production of biofuels generate hazardous by-products, one way to reduce them, by using reusable enzymatic process that requires insoluble enzyme carriers. This investigation allowed the obtention of magnetic graphene oxide (MGO) carrier containing aminosilane functional groups with and without the crosslinker glutaraldehyde. Thus, it was possible to immobilize cellulases and lipases enzymes and evaluate its enzymatic activity in normal conditions, as well as the novelty that was under alternating magnetic field (AMF) conditions. Through enzymatic essays it was determined the optimal working activities for both enzymes using these two magnetic carriers, being pH 4 and 60ºC for cellulases and pH 5 and 50ºC for lipase. Different frequencies were used during AMF test (20, 30, 50 and 70 kHz) and it was confirmed for both groups that with the increase in frequency during the reaction, the less pronounced will be the activity decrease at pH values different from the optimal condition. Due to magnetic properties from the carrier and the medium reaction used the recycle test was satisfactory for the two immobilized groups of the cellulase enzyme, being recycled 9 times without losses greater than 50 % of relative activity. As for the two groups of immobilized lipases, drastic decreases in activity were observed, possibly caused by the strong enzyme/substrate interaction. For both groups of immobilized enzymes, an inhibitory behavior of the glutaraldehyde reagent, widely used as an enzyme/carrier cross-linker, was also observed. Nevertheless, the immobilization of cellulase and lipases enzymes into MGO derivates shows a promising and suitable strategy for the conversion of cellulose and long-chain acyl esters into value-added inputs.

An electrostatically conjugated-functional MNK1 aptamer reverts the intrinsic antitumor effect of polyethyleneimine-coated iron oxide nanoparticles in vivo in a human triple-negative cancer xenograft

BackgroundTriple-negative breast cancer (TNBC) remains a difficult breast cancer subtype to treat as it exhibits a particularly aggressive behavior. The dysregulation of distinct signaling pathways underlies this aggressive behavior, with an overactivation of MAP kinase interacting kinases (MNKs) promoting tumor cell behavior, and driving proliferation and migration. Therefore, MNK1 is an excellent target to impair the progression of TNBC and indeed, an MNK1-specific aptamer has proved to be efficient in inhibiting TBNC cell proliferation in vitro. Although polyethyleneimine-coated iron oxide nanoparticles (PEI–IONPs) have been used as transfection and immunomodulating agents, no study has yet addressed the benefits of using these nanoparticles as a magnetic carrier for the delivery of a functional aptamer.ResultsHere, we tested the antitumor effect of a PEI–IONP complexed to the functional MNK1b-specific aptamer in vitro and in vivo. We demonstrated that these apMNKQ2@PEI–IONP nanoconjugates delivered three times more apMNKQ2 to MDA-MB-231 cells than the aptamer alone, and that this enhanced intracellular delivery of the aptamer had consequences for MNK1 signaling, reducing the amount of MNK1 and its target the phospho(Ser209)-eukaryotic initiation factor 4E (eIF4E). As a result, a synergistic effect of the apMNKQ2 and PEI–IONPs was observed that inhibited MDA-MB-231 cell migration, probably in association with an increase in the serum and glucocorticoid-regulated kinase-1 (SGK1) and the phospho(Thr346)-N-myc down-regulated gene 1 (NDRG1). However, intravenous administration of the apMNKQ2 alone did not significantly impair tumor growth in vivo, whereas the PEI–IONP alone did significantly inhibit tumor growth. Significantly, tumor growth was not inhibited when the apMNKQ2@PEI–IONP nanocomplex was administered, possibly due to fewer IONPs accumulating in the tumor. This apMNKQ2-induced reversion of the intrinsic antitumor effect of the PEI–IONPs was abolished when an external magnetic field was applied at the tumor site, promoting IONP accumulation.ConclusionsElectrostatic conjugation of the apMNKQ2 aptamer with PEI–IONPs impedes the accumulation of the latter in tumors, which appears to be necessary for PEI–IONPs to exert their antitumor activity.Graphical

Synthesis, Evaluation, and Electrochemical Detection Application of Magnetic Molecularly Imprinted Polymers for 4,4 ′ -Methylenedianiline from Food-Contact Materials

Magnetic molecularly imprinted polymers (MIPs) capable of selectively recognizing and absorbing 4,4 ′ -methylenedianiline (MDA) were successfully synthesized, using Fe3O4 coated with mesoporous silicon (Fe3O4@mSiO2) as the magnetic carrier, 4-vinyl pyridine (4-VP) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent, and MDA as the template molecule. The morphology, structure, and properties of MIPs were characterized, suggesting that the MIPs had obvious core-shell structure and strong magnetic responsiveness. The results of adsorption property tests showed that the MIPs could specifically recognize and adsorb MDA with excellent selectivity and reusability. The adsorption kinetic process could be described by the pseudo-second-order kinetic model, and the adsorption isotherm could be fitted by the Langmuir model, with a maximum adsorption capacity of 59.5 μmol/g. Furthermore, the magnetic MIPs have been applied to the electrochemical detection of MDA from the composite film sample, with recoveries in the range from 87.8% to 92.5% and the RSD values less than 4.4%. The prepared magnetic MIPs showed potential for the selective separation and detection of MDA in food-contact materials.

Effect of Particle–Particle and RBC–Particle Interactions on Capture Efficiency of Magnetic Nanocarriers Under the Influence of a Nonuniform Magnetic Field

In this study, the capture efficiency (CE) of magnetic carrier particles at the region of interest (ROI) in a micro-vessel was investigated. A nonuniform magnetic field produced by a Nd-Fe-B magnet was applied to capture the carrier particles at the ROI. The particle–particle and red blood cell (RBC)–carrier particle interactions were taken into account. Other parameters including carrier particle diameter, magnetic force, and non-Newtonian behavior of blood were also considered. The finite element method was used to solve the governing equations. Four cases were considered: (1) Newtonian without interaction forces, (2) Newtonian with interaction forces, (3) non-Newtonian without interaction forces, and (4) non-Newtonian with interaction forces. The results showed that for a particle diameter of 2000 nm, the CE values for the case without interaction force and with interaction force were 70% and 53%, respectively. It was found that by considering the particle–particle and RBC–carrier particle interactions for all magnet–vessel distances, the CE of carrier particles decreased, on average, by nearly 19%. At a magnet–vessel distance of 2.5 cm (d=2.5cm),\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d=2.5\\,\\mathrm{cm}),$$\\end{document} it was seen that the CE values for case 2 and case 3 were nearly 70% and 45%, representing the maximum and minimum CE values, respectively.

Paleomagnetism of late Cretaceous dykes in the Gangdese belt: New constraints on the position and structure of the southern margin of Asia prior to the India-Asia collision

We report paleomagnetic data from late Cretaceous diorite dykes that sub-vertically intrude granodiorites in the eastern Gangdese belt near the city of Lhasa. Our research goals are to provide further constraints on pre-collisional structure of the southern margin of Asia and the onset of the India-Asia collision. Magnetite is identified as the main magnetic carrier in our study. The magnetite shows no evidence of metamorphism or alteration as determined from optical and scanning electron microscope observations. A strong mineral orientation is revealed by anisotropy of magnetic susceptibility analysis both for the intruded dykes and the country rocks. We interpret this AMS fabric to have formed during intrusion rather than deformation. Fifteen of 23 sites yield acceptable site mean characteristic remanences with dual polarities. A scatter analysis of the virtual geomagnetic poles suggests that the mean result adequately averaged paleosecular variation. The paleomagnetic pole from the Gangdese dykes yields a paleolatitude of 14.3°N ± 5.8°N for the southern margin of Asia near Lhasa. The paleolatitude corresponds to an in-between position of the Lhasa terrane during ~130-60 Ma. Furthermore, the mean declination of the characteristic remanent magnetization reveals a significant counterclockwise rotation of 18° ± 9° for the sampling location since ~83 Ma. In the light of tectonic setting of the dykes, the strike of the southern margin of Asia near Lhasa is restored to trend approximately ~310°, which is compatible with the hypothesis that the southern margin of Eurasia had a quasi-linear structure prior to its collision with India.

Learning Trajectories from Spin-Wave Dynamics

The efficacy of a physical reservoir computer model based on traveling spin waves in a spin-wave delay-line active-ring resonator was demonstrated recently. In the present work, we investigate how this neuromorphic device can be adapted for sensing applications. In this ``reservoir computing for sensing'' framework, we exploit strong coupling of the physical reservoir to its environment to utilize the reservoir as a sensing element. The dynamics of traveling spin waves in delay-line active rings are strongly dependent on the magnetic field and carrier frequency of those spin waves. Treating the spin-wave frequency as an environmental variable, we excite the active ring into different dynamical states by modulating the carrier frequency of a drive signal of microwave pulses injected into the ring. Training a linear regression on the time-multiplexed output from the ring allows the periodic amplitude patterns of the spin waves to be mapped reproducibly onto two-dimensional trajectories, representing periodic ``behavioral'' targets. Our work demonstrates the versatility of a magnonic resonator as a multipurpose computing and sensing device.