Design of Three-Dimensional Magnetic Probe System for Space Plasma Environment Research Facility (SPERF).

A three-dimensional magnetic probe system has been designed and implemented at the Space Plasma Environment Research Facility (SPERF). This system has been developed to measure the magnetic field with high spatial and temporal resolution, enabling studies of fundamental processes in space physics, such as magnetic reconnection at the Earth's magnetopause, on the basis of SPERF. The system utilizes inductive components as sensors, arranged in an array and soldered onto a printed circuit board (PCB), achieving a spatial resolution of 2.5 mm. The system's electrical parameters have been measured, and its amplitude-frequency response characteristics have been simulated. The system has demonstrated good performance with response capabilities below 50 kHz. The experimental setup and results are discussed, highlighting the system's effectiveness in accurately measuring weak magnetic signals and its suitability for magnetic reconnection experiments.

Magnetic Relaxation Switching Immunosensors via a Click Chemistry-Mediated Controllable Aggregation Strategy for Direct Detection of Chlorpyrifos.

Chlorpyrifos (CPF) is the most frequently found organophosphate pesticide residue in solid food samples and can cause increasing public concerns about potential risks to human health. Traditional detection signals of such small molecules are mostly generated by target-mediated indirect conversion, which tends to be detrimental to sensitivity and accuracy. Herein, a novel magnetic relaxation switching detection platform was developed for target-mediated direct and sensitive detection of CPF with a controllable aggregation strategy based on a bioorthogonal ligation reaction between tetrazine (Tz) and trans-cyclooctene (TCO) ligands. Under optimal conditions, this sensor can achieve a detection limit of 37 pg/mL with a broad linear range of 0.1-500 ng/mL in 45 min, which is approximately 51-fold lower than that of the gas chromatography analysis and 13-fold lower than that of the enzyme-linked immunosorbent assay. The proposed click chemistry-mediated controllable aggregation strategy is direct, rapid, and sensitive, indicating great potential for residue screening in food matrices.

Switchable Broadband-to-Tunable Narrowband Magnetic Probe for Near-Field Measurements.

This paper presents a printed magnetic probe that can switch from broadband to tunable narrowband for near-field measurement. In the early design stage, we created a printed loop gap resonator as a magnetic reference sensor for the pre-compliance test in a band up to 6 GHz. Consequently, the results showed a good response in terms of the S11 and S21 parameters of the proposed probe compared with the commercial magnetic sensor XF-R 3-1. The source noise might spread among different frequency bands, making the broadband magnetic probe the closest choice for estimating the magnetic field in the near-field region. Unfortunately, broadband magnetic probes have lower sensitivity than narrowband ones. One of the solutions to get high sensitivity is to connect the LNA to the output of the passive magnetic sensor. This work proposes a novel method to solve this issue using a PIN diode to change the broadband status into a high sensitivity narrowband status and then tune this narrowband across the most critical applications such as 3.5 GHz, 3.75 GHz, 4.8 GHz, and 5.2 GHz with the help of a varactor diode. Compared to the broadband status, an improvement of more than 10 dB has been obtained across all these wireless bands. Furthermore, the proposed structure's isolation between the electrical and magnetic fields is about 13 dB.

Advances in the Biological Application of Force-Induced Remnant Magnetization Spectroscopy.

Biomolecules participate in various physiological and pathological processes through intermolecular interactions generally driven by non-covalent forces. In the present review, the force-induced remnant magnetization spectroscopy (FIRMS) is described and illustrated as a novel method to measure non-covalent forces. During the FIRMS measurement, the molecular magnetic probes are magnetized to produce an overall magnetization signal. The dissociation under the interference of external force yields a decrease in the magnetic signal, which is recorded and collected by atomic magnetometer in a spectrum to study the biological interactions. Furthermore, the recent FIRMS development with various external mechanical forces and magnetic probes is summarized.

Exploratory Study of Superparamagnetic Iron Oxide Dose Optimization in Breast Cancer Sentinel Lymph Node Identification Using a Handheld Magnetic Probe and Iron Quantitation.

This exploratory study compared doses of ferucarbotran, a superparamagnetic iron oxide nanoparticle, in sentinel lymph nodes (SLNs) and quantified the SLN iron load by dose and localization. Eighteen females aged ≥20 years scheduled for an SLN biopsy with node-negative breast cancer were divided into two equal groups and administered either 1 mL or 0.5 mL ferucarbotran. Iron content was evaluated with a handheld magnetometer and quantification device. The average iron content was 42.8 µg (range, 1.3-95.0; 0.15% of the injected dose) and 21.9 µg (1.1-71.0; 0.16%) in the 1-mL and 0.5-mL groups, respectively (p = 0.131). The iron content of the closest SLN compared to the second SLN was 53.0 vs. 10.0 µg (19% of the injected dose) and 34.8 vs. 4.1 µg (11.1%) for the 1-mL and 0.5-mL groups, respectively (p = 0.001 for both). The magnetic field was high in both groups (average 7.30 µT and 6.00 µT in the 1-mL and 0.5-mL groups, respectively) but was not statistically significant (p = 0.918). The magnetic field and iron content were correlated (overall SLNs, p = 0.02; 1-mL, p = 0.014; 0.5-mL, p = 0.010). A 0.5-mL dose was sufficient for SLN identification. Primary and secondary SLNs could be differentiated based on iron content. Handheld magnetometers could be used to assess the SLN iron content.

Sentinel lymph node biopsy with a handheld cordless magnetic probe following preoperative MR lymphography using superparamagnetic iron oxide for clinically N0 early oral cancer: A feasibility study.

PURPOSE: Radioisotope (RI) tracers are generally used for preoperative mapping of sentinel lymph node (SLN) and intraoperative detection with a portable γ probe. However, the use of RI has several limitations. Therefore, a method without RI is required for the widespread application of SLN biopsy. The purpose of this study was to evaluate the feasibility of SLN biopsy with a handheld cordless magnetic probe following magnetic resonance lymphography (MRL) using superparamagnetic iron oxide (SPIO) and for clinically N0 early oral cancer. MATERIALS AND METHODS: MRL using SPIO and SLNB with the handheld cordless magnetic probe were performed for 27 patients with clinically N0 early oral cancer. RESULTS: In all 27 patients (100%), SLNs were detected by MRL, and the total and mean number of SLNs were 73 and 2.7, respectively. All SLNs identified by MRL were detectable using the magnetic probe in all patients. CONCLUSIONS: SLNB with handheld cordless magnetic probe following preoperative SLN mapping by MRL using SPIO is feasible, without RI use, for neck management in cases of clinically N0 early oral cancer.

Magnetically Guided Localization Using a Guiding-Marker System® and a Handheld Magnetic Probe for Nonpalpable Breast Lesions: A Multicenter Feasibility Study in Japan.

Accurate pre-operative localization of nonpalpable lesions plays a pivotal role in guiding breast-conserving surgery (BCS). In this multicenter feasibility study, nonpalpable breast lesions were localized using a handheld magnetic probe (TAKUMI) and a magnetic marker (Guiding-Marker System®). The magnetic marker was preoperatively placed within the target lesion under ultrasound or stereo-guidance. Additionally, a dye was injected subcutaneously to indicate the extent of the tumor excision. Surgeons checked for the marker within the lesion using a magnetic probe. The magnetic probe could detect the guiding marker and accurately localize the target lesion intraoperatively. All patients with breast cancer underwent wide excision with a safety margin of ≥5 mm. The presence of the guiding-marker within the resected specimen was the primary outcome and the pathological margin status and re-excision rate were the secondary outcomes. Eighty-seven patients with nonpalpable lesions who underwent BCS, from January to March of 2019 and from January to July of 2020, were recruited. The magnetic marker was detected in all resected specimens. The surgical margin was positive only in 5/82 (6.1%) patients; these patients underwent re-excision. This feasibility study demonstrated that the magnetic guiding localization system is useful for the detection and excision of nonpalpable breast lesions.

Fibre Distribution Characterization of Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) Plates using Magnetic Probes.

Ultra-high performance fibre reinforced concrete (UHPFRC) is an innovative cement-based engineering material. The mechanical properties of UHPFRC not only depend on the properties of the concrete matrix and fibres, but also depend on the interaction between these two components. The fibre distribution is affected by many factors and previous researchers had developed different approaches to test the fibre distribution. This research adopted the non-destructive C-shape ferromagnetic probe inductive test and investigated the straight steel fibre distribution of the UHPFRC plate. A simplified characterization equation is introduced with an attenuation factor to consider the different plate thicknesses. The effective testing depth of this probe was tested to be 24 mm. By applying this method, fibre volume content and the fibre orientation angle can be calibrated for the entire plate. The fibre volume content generally fulfilled the design requirement. The fibre orientation angle followed a normal distribution, with a mean value of 45.60°. By testing small flexural specimens cut from the plates, it was found out that the mechanical performance (peak flexural strength) correlates with the product of fibre volume content and cosine fibre orientation angle.

Gd3+-nanoparticle-enhanced multivalent biosensing that combines magnetic relaxation switching and magnetic separation.

In this work, we developed a multivalent magnetic biosensing strategy by integrating magnetic separation and magnetic relaxation switching (MRS) where Gd3+-loaded magnetic nanoparticles acted as the probe. As a transition metal ion, Gd3+ has multiple unpaired electrons in the d-orbitals that can induce a strong fluctuating magnetic field and thus can reduce the transverse relaxation time (T2), contributing to a strong magnetic signal. By loading Gd3+ onto magnetic nanoparticles, we prepared a multivalent magnetic probe that combined magnetic separation and MRS for the signal readout. This multivalent sensing technique simplified the procedures and greatly enhanced the detection sensitivity of conventional MRS assays. A sensitive detection of ractopamine in real samples has been demonstrated with this multivalent sensing technique. The magnetic probe enabled the detection of ractopamine in a linear range from 0.1 to 100 ng/mL and the limit of detection was 20 pg/mL, a 25-fold enhancement in the sensitivity compared with conventional MRS assays. This Gd3+-nanoparticle-mediated MRS biosensor is a potential magnetic platform to detect trace levels of targets in complex samples.

Multicenter clinical trial on sentinel lymph node biopsy using superparamagnetic iron oxide nanoparticles and a novel handheld magnetic probe.

BACKGROUND: Sentinel lymph node biopsy is a standard staging procedure for early axillary lymph node-negative breast cancer. As an alternative to the currently used radioactive tracers for sentinel lymph node (SLN) detection during the surgical procedure, a number of studies have shown promising results using superparamagnetic iron oxide (SPIO) nanoparticles. Here, we developed a new handheld, cordless, and lightweight magnetic probe for SPIO detection. METHODS: Resovist (SPIO nanoparticles) were detected by the newly developed handheld probe, and the SLN detection rate was compared to that of the standard radioisotope (RI) method using radioactive colloids (99m Tc) and a blue dye (indigo carmine). This was a multicenter prospective clinical trial that included 220 patients with breast cancer scheduled for sentinel node biopsy after a clinical diagnosis of negative axillary lymph node from three facilities in Japan. RESULTS: Of the 210 patients analyzed, SLN was detected in 94.8% (199/210 cases, 90% confidence interval [CI]) with our magnetic method and in 98.1% (206/210 cases, 90% CI) with the RI method. The magnetic method exceeded the threshold identification rate of 90%. CONCLUSION: This was the first clinical study to use a novel handheld magnetometer to detect SLN, which we demonstrate to be not inferior to the RI method.

Localization of impalpable breast lesions and detection of sentinel lymph nodes through magnetic methods.

PURPOSE: The most commonly used technique for guiding the surgical removal of impalpable breast lesions is wire-guided localization (WGL). Potential complications of WGL include wire migration, wire transection, patient discomfort, and pneumothorax. Recently, another possibility for preoperative localization of breast lesions trough small steel seeds was developed. A magnetic handheld probe can be used both for localization of breast lesions and sentinel lymph nodes (SLNs) detection. METHODS: In this study, we used a new technology for localizing breast lesions in conjunction with sentinel nodes (SLNs) detection through SPIO nanoparticles; both detected using a magnetic probe. The technique uses small steel markers (Magseed®) with magnetic properties, which are placed in breasts under ultrasonographic or mammographic guidance. 41 localization seeds were placed in 38 patients. In 27 patients with malignant tumors, simultaneous use of magnetic method for SLNs detection was used. RESULTS: In all 38 patients, breast lesions were accurately localized using this method. No interference between Magseed signals and SPIO tracer signals were observed during magnetic probe measurements. All tumors were exscised with tumor-free surgical margins. The SLN biopsy was successful in all patients undergoing this procedure. The SLN median detection rate was 3 nodes. CONCLUSIONS: The new magnetic methods are reliable alternatives for localizing breast lesions and SLN detection. They are well tolerated by patients and they can avoid the disadvantages of WGL. They have the potential to make tumor localization and SLN biopsy procedures possible in facilities without a nuclear medicine department or where radioisotope availability is limited.

Magnetic nanocomposite-based SELDI probe for extraction and detection of drugs, amino acids and fatty acids.

The use of carbon black-Fe3O4 magnetic nanocomposite (CB-Fe3O4) as a probe for surface-enhanced laser desorption ionization mass spectrometry (SELDI-MS) with a high extraction efficiency and sensitive detection is described. The magnetic nanocomposite was synthesized and fully characterized using X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, Ultraviolet-Visible spectroscopy, transmission electron microscopy and nitrogen sorption. The feasibility of the SELDI probe to extract and detect three classes of drugs (labetalol, metoprolol, doxepin, desipramine, triprolidine and methapyrilene) spiked in wine is demonstrated. All the drugs were successfully and reproducibly extracted and detected with high efficiency and with limits of detection (LOD) between 1 and 1000 pg mL-1. The adsorption capacity of the nanocomposite for the drugs was evaluated by UV-Vis spectroscopy. The results showed that 27.8-36.1% of the drugs were adsorbed on the magnetic probe within 3 min. The nanocomposite was also applied for efficient analysis of amino acids and fatty acids. Both types of analytes can be extracted within a few minutes and then successfully quantified by SELDI-MS. Graphical abstract A schematic presentation of carbon black-Fe3O4 magnetic probe for SELDI analysis of small molecules. The probe containing the analyte(s) is collected with the aid of a magnet and deposited on the target plate for mass spectrometry analysis.

Fabrication of hydrophilic multilayer magnetic probe for salivary glycopeptidome analysis.

Variations in salivary components are closely associated with the predisposition and state of disease, the abnormal changes of salivary glycopeptidome are usually discovered as perilous singals of serious disease. Therefore, the monitoring and analyzing of salivary glycopeptidome are of even more overriding importance. In this work, a low-cost layer-by-layer assembly strategy was adopted to fabricate a hydrophilic multilayer magnetic probe (dubbed Mag-m-G6P) for salivary glycopeptidome analysis. The successful construction of multilayer structure not only guaranteed the good dispersal of probe by protecting magnetic core from itself aggregation tendency, but also endowed the probe with multiple advantages including the good hydrophilicity, uniform mesopore size and strong magnetic responsiveness, etc. As expected, with the optimized experimental conditions, the multifunctional probe showed high enrichemnt sensitivity, unbiased enrichment ability, excellent size-exclusion ability and reusability and so on in the process of standard sample analysis. At last, the Mag-m-G6P was successfully applied to salivary glycopeptidome analysis on further combination with LC-MS/MS analysis, a total of 53 endogenous glycopeptides were identified from human saliva.

Probing the Regioselectivity with Encapsulated H2 : Diels-Alder Reaction of an Open-Cage C60 Derivative with Anthracene.

The regioselectivity in the Diels-Alder reaction of an unsymmetrical open-cage C60 derivative with anthracene was studied. By using an encapsulated H2 molecule as a magnetic probe, the product population was successfully evaluated in detail, indicating the formation of approximately ten compounds as major components. The nucleus-independent chemical shift (NICS) calculations showed a close resemblance to the observed 1 H NMR spectrum, which allowed for a facile characterization of the products. Theoretical studies on the formation of all 29 possible anthracene adducts were also performed. The results indicated that the regioselectivity is strongly governed by steric factors, values of the frontier orbital coefficients, and thermodynamic stabilities. Single-crystal X-ray analysis of the dominant compound revealed the supramolecular architecture between the anthracene moiety and the π-sphere of a neighboring molecule.

Cleaning of contaminated MFM probes using a BOPP film and external magnetic field.

When magnetic samples are tested with a magnetic force microscope (MFM), the probe tip can inevitably be contaminated and magnetic particles are often adhered to the tip surface. The probe with magnetic contamination will seriously affect the quality of morphological and magnetic imaging. In the work, a method for the cleaning of contaminated magnetic probe tips was developed by the use of a biaxially-oriented polypropylene (BOPP) film together with an external magnet field in an MFM system. In the experiments, an MFM system was used for manipulating the tip to push into the BOPP film with a depth of 50-100nm under a magnetic field and hold for 5s, and the relationships between loading forces and separating forces were studied. The scanning electron microscope (SEM) images have shown that the use of the BOPP film together with an external magnet field is effective for the cleaning of contaminated MFM probes. This method can greatly improve the quality of magnetic imaging, prolong the service life of magnetic probes and reduce the experimental costs in many MFM applications.

Magnetic Probe-Guided Excision of Nonpalpable Neck Lesions.

BACKGROUND: Reoperative neck surgery is technically more demanding because of the presence of scar tissue and distorted anatomy. We aimed to investigate the magnetic probe-guided excision of nonpalpable neck lesions in patients with previously operated neck compartments. METHODS: This study included 9 patients with recurrent/persistent thyroid carcinoma, recurrent/persistent hyperparathyroidism with previously operated neck compartments. The pathologic lesions were localized by ultrasonography, and magnetic tracer (0.2 mL, iron oxide) was injected directly into the pathologic lesions. Careful dissection was carried out following the area of maximum magnetic activity until the nonpalpable lesions were identified and excised. RESULT: All neck lesions were removed in 9 patients. The median count from lesion was significantly higher than values from lesion bed (background activity; (9900/5 seconds vs 250/5 seconds, P < .001). During follow-up, all patients had negative ultrasonography. CONCLUSION: Magnetic probe-guided technique could provide access to nonpalpable lesion localization in centers without readily available access to nuclear medicine facilities.

Effect of horizontal magnetization reversal of the tips on magnetic force microscopy images.

The effect of magnetization reversal of magnetic force microscope (MFM) tips based on low coercive thin-films on MFM images has been studied both experimentally and theoretically. By analyzing the MFM images obtained on structures with high magnetic stray fields we show that during the imaging process the magnetic state of the probe is modified anisotropically: the horizontal component of the magnetization follows the external field, whereas the vertical component of the magnetization stays almost constant. The observed complex magnetic behavior of the tip is explained theoretically based on the shape anisotropy of the tip. The obtained results are important for interpretation of MFM images of structures with high magnetic moment. Moreover, these results can be used for characterization of both laboratory-made and commercially available MFM tips.