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Mission-critical embedded systems simultaneously run multiple graphics-processing-unit (GPU) computing tasks with different criticality and timeliness requirements. Considerable research effort has been dedicated to supporting the preemptive priority scheduling of GPU kernels. However, hardware-supported preemption leads to lengthy scheduling delays and complicated designs, and most software approaches depend on the voluntary yielding of GPU resources from restructured kernels. We propose a preemptive GPU kernel scheduling scheme that harnesses the idempotence property of kernels. The proposed scheme distinguishes idempotent kernels through static source code analysis. If a kernel is not idempotent, then GPU kernels are transactionized at the operating system (OS) level. Both idempotent and transactionized kernels can be aborted at any point during their execution and rolled back to their initial state for reexecution. Therefore, low-priority kernel instances can be preempted for high-priority kernel instances and reexecuted after the GPU becomes available again. Our evaluation using the Rodinia benchmark suite showed that the proposed approach limits the preemption delay to 18 $\mu$ μ s in the 99.9th percentile, with an average delay in execution time of less than 10 percent for high-priority tasks under a heavy load in most cases.

We demonstrated a simple one-pot synthesis approach for the controlled composition of homogeneous FePt and phase-controlled heterostructured FePt/Fe3O4 nanocubes (NCs) utilizing 1,2-hexadecanediol and 1-octadecene as the reducing agents, respectively. When the Fe : Pt precursor ratio was varied from 1 : 1 to 4 : 1 and 1,2-hexadecanediol was utilized as the reducing agent, homogeneous FePt NCs were formed, whereas the heterostructures of FePt/Fe3O4 NCs were obtained when utilizing 1-octadecene as the reducing agent at Fe : Pt ratio of 4 : 1. The initial domination of nucleation of Pt-rich species and the subsequent deposition of Fe atoms leads to the formation of homogeneous FePt NCs. Heterostructured FePt/Fe3O4 NCs were obtained by the initial FePt seed formation, which was then followed by the heterogeneous growth of Fe3O4. The heterostructured FePt/Fe3O4 NCs exhibited two phases, i.e., FePt phase with a (111) facet of the fcc and Fe3O4 phase with an inverse cubic spinel structure. Moreover, both the FePt and the FePt/Fe3O4 NCs demonstrated almost negligible coercivity, which confirmed a typical superparamagnetic behavior. Furthermore, the cell viability tests of the FePt and FePt/Fe3O4 NCs demonstrated excellent biocompatibilities. Hence, the NCs could be useful for various biomedical applications, including MRI contrast agents, hyperthermia, and as a label in magnetic biochips.

Herein, we have reported the real-time photodegradation of methylene blue (MB), an organic pollutant, in the presence of sunlight at an ambient temperature using a platinum-decorated reduced graphene oxide (rGO/Pt) nanocomposite. The photocatalyst was prepared via a simple, one-pot and green approach with the simultaneous reduction of GO and Pt using aqueous honey as a reducing agent. Moreover, the honey not only simultaneously reduced Pt ions and GO but also played a key role in the growth and dispersion of Pt nanoparticles on the surface of rGO. Various rGO/Pt nanocomposites with different percentages of Pt nanoparticles loaded on rGO were obtained by tuning the concentration of the Pt source. The high percentage of Pt nanoparticles with an average size of 2.5 nm dispersed on rGO has shown excellent electrochemical performance. The photocatalytic activity of the rGO/Pt composite was enhanced by increasing the weight percent of the Pt particles on rGO, which led to the formation of a highly efficient photocatalyst. The optimized photocatalyst exhibited remarkable photocatalytic activity and degraded 98% MB in 180 minutes; thus, it can be used for industrial and environmental applications.

Simple Summary The development of new approaches in the field of drug delivery systems is primarily based on increasing the accuracy and precision of the targeted site and improving the stability of the drug by preventing the phagocytosis process inside the body. Among many other methods used to fulfill the above-mentioned requirements, the use of magnetotactic bacteria (MTB) is proven to be a promising solution, as it is self-propelling in nature, and can also be controlled by an external magnetic field. For the present work, we developed an MTB/PEG–biotin complex by exploiting the process of covalent bond formation between bacteria and a biotin–PEG–NHS polymer. In addition to this, attachment efficacy and stability were also determined. In biological applications, cytotoxicity assay of THP-1 cells was performed, showing the MTB/PEG–biotin complex to be less harmful to the cells; meanwhile, to explore the stealth properties of the complex, we performed a cell association assay. With these results, we provide a significant contribution to the field of potential drug delivery system development. Abstract The early removal of drug delivery agents before reaching the affected target remains an area of interest to researchers. Several magnetotactic bacteria (MTB) have been used as self-propelled drug delivery agents, and they can also be controlled by an external magnetic field. By attaching the PEG–biotin polymer, the bacteria are turned into a stealth material that can escape from the phagocytosis process and reach the area of interest with the drug load. In the study, we developed a potential drug carrier by attaching the PEG–biotin to the MTB-through-NHS crosslinker to form a MTB/PEG–biotin complex. The attachment stability, efficacy, and bacterial viability upon attachment of the PEG–biotin polymer were investigated. Biological applications were carried out using a cytotoxicity assay of THP-1 cells, and the results indicate that the MTB/PEG–biotin complex is less harmful to cell viability compared to MTB alone. Along with cytotoxicity, an assay for cell association was also evaluated to assess the complex as a potential stealth material. The development of these complexes focuses on an easy, time-saving, and stable technique of polymer attachment with the bacteria, without damaging the cell’s surface, so as to make it a strong and reliable delivery agent.

The limited memory capacity of mobile devices leads to the popular use of compressed swap schemes, which reduce the I/O operations involving the swapping in and out of infrequently accessed pages. However, most of the current compressed swap schemes indiscriminately compress and store all swap-out pages. Considering that both energy and computing power are scarce resources in mobile devices, and modern applications frequently deal with already-compressed multimedia data, this blind approach may cause adverse impacts. In addition, they focus only on anonymous pages and not on file-mapped pages, because the latter are backed by on-disk files. However, our observations revealed that, in mobile devices, file-mapped pages consume significantly more memory than anonymous pages. Last but not least, most of the current compressed swap schemes blindly follow the least-recently-used (LRU) discipline when choosing the victim pages for replacement, not considering the compression ratio or data density of the cached pages. To overcome the aforementioned problems and maximize the memory efficiency, we propose a compressed swap scheme, called enhanced zswap (ezswap), for mobile devices. ezswap accommodates not only anonymous pages, but also clean file-mapped pages. It estimates the compression ratio of incoming pages with their information entropy, and selectively compresses and caches the pages only with beneficial compression ratios. In addition, its admission control and cache replacement algorithms are based on a cost-benefit model that considers not only the access recency of cached pages but also their information density and expected eviction cost. The proposed scheme was implemented in the Linux kernel for Android. Our evaluation with a series of commercial applications demonstrated that it reduced the amount of flash memory read by up to 55%, thereby improving the application launch time by up to 22% in comparison to the original zswap.

In article number 2100532, Sri Ramulu Torati, CheolGi Kim, and co‐workers develop the magnetophoretic decoupler for the disaggregation and inter‐particle distance control of magnetic bead cluster for higher efficiency of bio‐carrier role. This magnetophoretic decoupler can split the multiple bead pairs in different directions using single driving force, and linearly control the inter‐particle distance between them through the angle of the external field. [Image: see text]

Advanced microelectromechanical system (MEMS) magnetic field sensor applications demand ultra-high detectivity down to the low magnetic fields. To enhance the detection limit of the magnetic sensor, a resistance compensator integrated self-balanced bridge type sensor was devised for low-frequency noise reduction in the frequency range of 0.5 Hz to 200 Hz. The self-balanced bridge sensor was a NiFe (10 nm)/IrMn (10 nm) bilayer structure in the framework of planar Hall magnetoresistance (PHMR) technology. The proposed resistance compensator integrated with a self-bridge sensor architecture presented a compact and cheaper alternative to marketable MEMS MR sensors, adjusting the offset voltage compensation at the wafer level, and led to substantial improvement in the sensor noise level. Moreover, the sensor noise components of electronic and magnetic origin were identified by measuring the sensor noise spectral density as a function of temperature and operating power. The lowest achievable noise in this device architecture was estimated at ~3.34 nV/Hz at 100 Hz.

Manipulating and separating single label-free cells without biomarker conjugation have attracted significant interest in the field of single-cell research, but digital circuitry control and multiplexed individual storage of single label-free cells remain a challenge. Herein, by analogy with the electrical circuitry elements and electronical holes, we develop a pseudo-diamagnetophoresis (PsD) mattertronic approach in the presence of biocompatible ferrofluids for programmable manipulation and local storage of single PsD holes and label-free cells. The PsD holes conduct along linear negative micro-magnetic patterns. Further, eclipse diode patterns similar to the electrical diode can implement directional and selective switching of different PsD holes and label-free cells based on the diode geometry. Different eclipse heights and junction gaps influence the switching efficiency of PsD holes for mattertronic circuitry manipulation and separation. Moreover, single PsD holes are stored at each potential well as in an electrical storage capacitor, preventing multiple occupancies of PsD holes in the array of individual compartments due to magnetic Coulomb-like interaction. This approach may enable the development of large programmable arrays of label-free matters with high throughput, efficiency, and reliability as multiplex cell research platforms., Here, the authors present a pseudo-diamagnetophoresis mattertronic approach for programmable manipulation of label-free cells. Immersed in biocompatible ferrofluids, single cells are moved along linear negative micromagnetic patterns, switched at eclipse diode patterns and stored in potential wells.

Herein, we have reported the real-time photodegradation of methylene blue (MB), an organic pollutant, in the presence of sunlight at an ambient temperature using a platinum-decorated reduced graphene oxide (rGO/Pt) nanocomposite. The photocatalyst was prepared

We fabricate on-chip micromagnets using Ni80Fe20 and Co70Fe30 materials for the characterization of mobility of superparamagnetic particles. The maximum velocity of the particles around the periphery of the micromagnets is determined by the critical frequency, which indicates that the particle enters the phase-slipping regime from the phase-locked regime. The maximum velocity of NiFe micromagnets is approximately 3 times larger than that of CoFe micromagnets measured at the low field regions. Moreover, the maximum velocity of the particles is decreasing with increasing the thickness of Teflon coating on the micromagnets, which is in a good agreement with the variation of the magnetostatic potential energy evaluated numerically from micromagnetic simulations.

Magnetic flux leakage (MFL) detection is frequently used for oil and gas pipeline inspection, especially for evaluation of the integrity of pipelines. The success of the MFL technique depends on many parameters. However, a sensitive magnetic sensor is an important requirement. Therefore, magnetic field sensors based on different mechanisms have been developed and applied to the MFL technique. In this paper, we evidence for the first time the capability of an innovative device based on a planar Hall magnetoresistance sensor devoted to MFL detection. This promising prototype combines all the required qualifications such as high sensitivity, low thermal drift, and bipolar and linear responses to the magnetic field. New achievements are carried out on embedded sensors in a testing platform reflecting pipeline environments. The ultrasensitive magnetic mapping concludes to a convincing technical approach with a high potential application toward MFL inspection, especially for the detection of shallow defects appearing at near side, far side, and sub-surface of a pipe wall.

Cell clustering techniques are important to produce artificial cell clusters for in vitro models of intercellular mechanisms at the single-cell level. The analyses considering physical variables such as the shape and size of cells have been very limited. In addition, the precise manipulation of cells and control of the physical variables are still challenging. In this paper, a magnetophoretic device consisting of a trampoline micromagnet and active elements that enable the control of individual selective jumping motion and positioning of a micro-object is proposed. Based on a numerical simulation under various conditions, automatic separation or selective clustering of micro-objects according to their sizes is performed by parallel control and programmable manipulation. This method provides efficient control of the physical variables of cells and grouping of cells with the desired size and number, which can be a milestone for a better understanding of the intercellular dynamics between clustered cells at the single-cell level for future cell-on-chip applications.

The resolution of planar-Hall magnetoresistive (PHMR) sensors was investigated in the frequency range from 0.5 Hz to 200 Hz in terms of its sensitivity, average noise level, and detectivity. Analysis of the sensor sensitivity and voltage noise response was performed by varying operational parameters such as sensor geometrical architectures, sensor configurations, sensing currents, and temperature. All the measurements of PHMR sensors were carried out under both constant current (CC) and constant voltage (CV) modes. In the present study, Barkhausen noise was revealed in 1/f noise and found less significant in the PHMR sensor configuration. under measured noise spectral density at optimized conditions, the best magnetic field detectivity was achieved better than 550 pT/√ Hz at 100 Hz and close to 1.1 nT/√ Hz at 10 Hz for a tri-layer multi-ring PHMR sensor in an unshielded environment. Furthermore, the promising feasibility and possible routes for further improvement of the sensor resolution are discussed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Data Availability Statement: All data generated or analyzed during this work are included in funded by the MSIT (No. NRF-2018R11025511) and R&D program of MOTIE (No. 20011264). funded by the MSIT (No. NRF-2018R11025511) and R&D program of MOTIE (No. 20011264).

Mechanoreceptors in a fingertip convert external tactile stimulations into electrical signals, which are transmitted by the nervous system through synaptic transmitters and then perceived by the brain with high accuracy and reliability. Inspired by the human synapse system, this paper reports a robust tactile sensing system consisting of a remote touch tip and a magnetic synapse. External pressure on the remote touch tip is transferred in the form of air pressure to the magnetic synapse, where its variation is converted into electrical signals. The developed system has high sensitivity and a wide dynamic range. The remote sensing system demonstrated tactile capabilities over wide pressure range with a minimum detectable pressure of 6 Pa. In addition, it could measure tactile stimulation up to 1,000 Hz without distortion and hysteresis, owing to the separation of the touching and sensing parts. The excellent performance of the system in terms of surface texture discrimination, heartbeat measurement from the human wrist, and satisfactory detection quality in water indicates that it has considerable potential for various mechanosensory applications in different environments.

Magnetoresistive (MR) sensors have been identified as promising candidates for the development of high-performance magnetometers due to their high sensitivity, low cost, low power consumption, and small size. The rapid advance of MR sensor technology has opened up a variety of MR sensor applications. These applications are in different areas that require MR sensors with different properties. Future MR sensor development in each of these areas requires an overview and a strategic guide. An MR sensor roadmap (non-recording applications) was therefore developed and made public by the Technical Committee of the IEEE Magnetics Society with the aim to provide an research and development (R&D) guide for MR sensors intended to be used by industry, government, and academia. The roadmap was developed over a three-year period and coordinated by an international effort of 22 taskforce members from ten countries and 17 organizations, including universities, research institutes, and sensor companies. In this paper, the current status of MR sensors for non-recording applications was identified by analyzing the patent and publication statistics. As a result, timescales for MR sensor development were established and critical milestones for sensor parameters were extracted in order to gain insight into potential MR sensor applications (non-recording). Five application areas were identified, and five MR sensor roadmaps were established. These include biomedical applications, flexible electronics, position sensing and human-computer interactions, non-destructive evaluation and monitoring, and navigation and transportation. Each roadmap was analyzed using a logistic growth model, and new opportunities were predicted based on the extrapolated curve, forecast milestones, and professional judgment of the taskforce members. This paper provides a framework for MR sensor technology (non-recording applications) to be used for public and private R&D planning, in order to provide guidance into likely MR sensor applications, products, and services expected in the next 15 years and beyond. This work was supported in part by the Seed Funding Program for Basic Research, in part by the Seed Funding Program for Applied Research and Small Project Funding Program from the University of Hong Kong, and in part by ITF Tier 3 funding under Grant ITS/203/14, Grant ITS/104/13, and Grant ITS/214/14), in part by RGC-GRF under Grant HKU 17210014 and Grant HKU 17204617, and in part by the University Grants Committee of Hong Kong under Contract AoE/P-04/08.

The manipulation of superparamagnetic beads has attracted various lab on a chip and magnetic tweezer platforms for separating, sorting, and labeling cells and bioentities, but the irreversible aggregation of beads owing to magnetic interactions has limited its actual functionality. Here, an efficient solution is developed for the disaggregation of magnetic beads and interparticle distance control with a magnetophoretic decoupler using an external rotating magnetic field. A unique magnetic potential energy distribution in the form of an asymmetric magnetic thin film around the gap is created and tuned in a controlled manner, regulated by the size ratio of the bead with a magnetic pattern. Hence, the aggregated beads are detached into single beads and transported in one direction in an array pattern. Furthermore, the simultaneous and accurate spacing control of multiple magnetic bead pairs is performed by adjusting the angle of the rotating magnetic field, which continuously changes the energy well associated with a specific shape of the magnetic patterns. This technique offers an advanced solution for the disaggregation and controlled manipulation of beads, can allow new possibilities for the enhanced functioning of lab on a chip and magnetic tweezers platforms for biological assays, intercellular interactions, and magnetic biochip systems., This study reports the real‐time disaggregation and interdistance control of the magnetic beads using magnetophoretic decoupler fabricated with permalloy thin film pattern. The application of a rotating magnetic field creates a unique magnetic potential energy distribution around the decoupler at multiple points, and thus, separates the aggregated beads and transported them on the pattern to the desired direction.

CoFe2O4 and Fe3O4 nanoparticles with controllable morphology were synthesized using a convenient and facile one-pot thermal decomposition method. Iron(III) acetylacetonate and cobalt(II) acetylacetonate were used as precursors instead of the toxic and expensive pentacarbonyl, and oleic acid and oleylamine employed as solvents, stabilizers, and reducing agents. The nanoparticles exhibit well-defined shapes of varying size and their morphology can be tuned by modifying the reaction time, solvent, and temperature. Transmission electron microscopy, energy dispersive spectroscopy and X-ray diffraction were utilized to confirm the unique morphology, high crystallinity, composition and pure phase structure. Magnetic characterization of the nanoparticles further revealed the highest saturation magnetization value of 80.93 and 92.94 emu per g obtained for the cubic shape in the case of both CoFe2O4 and Fe3O4, respectively.

Herein, a novel temperature sensor is proposed employing a planar Hall resistance (PHR) magnetic sensor, a magnet sheet, and an expanding polymer. It features a tunable temperature range, high linear sensitivity, accuracy, and cycling stability through 1000 cycles, and no thermal hysteresis. This new sensor is promising as a body temperature sensor.

In this paper, we propose a high accuracy open-type current sensor with a differential Planar Hall Resistive (PHR) sensor. Conventional open-type current sensors with magnetic sensors are usually vulnerable to interference from an external magnetic field. To reduce the effect of an unintended magnetic field, the proposed design uses a differential structure with PHR. The differential structure provides robust performance to unwanted magnetic flux and increased magnetic sensitivity. In addition, instead of conventional Hall sensors with a magnetic concentrator, a newly developed PHR with high sensitivity is employed to sense horizontal magnetic fields. The PHR sensor and read-out integrated circuit (IC) are integrated through a post-Complementary metal-oxide-semiconductor (CMOS) process using multi-chip packaging. The current sensor is designed to measure a 1 A current level. The measured performance of the designed current sensor has a 16 kHz bandwidth and a current nonlinearity of under &plusmn, 0.5%.

Monodisperse Mn x Zn 1− x Fe 2 O 4 ( x = 0.2, 0.5 and 0.8) nanoparticles have been synthesized using two different routes namely sonochemical and polyol methods, and the shape and size along with physiochemical properties of the nanoparticles were compared in detail. In both the routes, the synthesis was performed in a single reaction without the use of any surfactant and deoxygenated conditions. The reaction kinetics and surface adsorption characteristics of nanoparticles were observed by thermogravimetric analysis and Fourier transform infrared spectroscopy measurements. X-ray diffraction patterns confirmed the formation of a pure ferrite phase with cubic spinel structure, and the patterns further clearly indicate that the sonochemical method produces highly crystalline particles without any post calcination reaction, comparing with the polyol process. Transmission electron microscopy results reveal that the nanoparticles synthesized by polyol method are mostly aggregated and spherical in nature whereas the nanoparticles produced by sonochemical method are monodisperse large particles with cubic like shapes. The overall studies demonstrated that the sonochemical method is facile, reliable, rapid and very attractive for the aqueous synthesis of highly crystalline and high magnetic moment (84.5 emu/g) monodisperse superparamagnetic Mn–Zn ferrite nanoparticles which considered as potential materials for various applications.

Sri Ramulu Torati,1 Venu Reddy,1 Seok Soo Yoon,2 CheolGi Kim1 1Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea; 2Department of Physics, Andong National University, Andong, South Korea Abstract: CoFe nanowires have been synthesized by the electrodeposition technique into the pores of a polycarbonate membrane with a nominal pore diameter of 50 nm, and the composition of CoFe nanowires varying by changing the source concentration of iron. The synthesized nanowire surfaces were functionalized with amine groups by treatment with aminopropyltriethoxysilane (APTES) linker, and then conjugated with streptavidin-Cy3 protein via ethyl (dimethylaminopropyl) carbodiimideand N-hydroxysuccinimide coupling chemistry. The oxide surface of CoFe nanowire is easily modified with aminopropyltriethoxysilane to form an amine terminating group, which is covalently bonded to streptavidin-Cy3 protein. The physicochemical properties of the nanowires were analyzed through different characterization techniques such as scanning electron microscope, energy dispersive spectroscopy, and vibrating sample magnetometer. Fluorescence microscopic studies and Fourier transform infrared studies confirmed the immobilization of protein on the nanowire surface. In addition, the transmission electron microscope analysis reveals the thin protein layer which is around 12–15 nm on the nanowire surfaces. Keywords: electrodeposition, biofunctionalization, streptavidin

Building upon the success and relevance of the 2014 Magnetism Roadmap, this 2017 Magnetism Roadmap edition follows a similar general layout, even if its focus is naturally shifted, and a different group of experts and, thus, viewpoints are being collected and presented. More importantly, key developments have changed the research landscape in very relevant ways, so that a novel view onto some of the most crucial developments is warranted, and thus, this 2017 Magnetism Roadmap article is a timely endeavour. The change in landscape is hereby not exclusively scientific, but also reflects the magnetism related industrial application portfolio. Specifically, Hard Disk Drive technology, which still dominates digital storage and will continue to do so for many years, if not decades, has now limited its footprint in the scientific and research community, whereas significantly growing interest in magnetism and magnetic materials in relation to energy applications is noticeable, and other technological fields are emerging as well. Also, more and more work is occurring in which complex topologies of magnetically ordered states are being explored, hereby aiming at a technological utilization of the very theoretical concepts that were recognised by the 2016 Nobel Prize in Physics. Given this somewhat shifted scenario, it seemed appropriate to select topics for this Roadmap article that represent the three core pillars of magnetism, namely magnetic materials, magnetic phenomena and associated characterization techniques, as well as applications of magnetism. While many of the contributions in this Roadmap have clearly overlapping relevance in all three fields, their relative focus is mostly associated to one of the three pillars. In this way, the interconnecting roles of having suitable magnetic materials, understanding (and being able to characterize) the underlying physics of their behaviour and utilizing them for applications and devices is well illustrated, thus giving an accurate snapshot of the world of magnetism in 2017. The article consists of 14 sections, each written by an expert in the field and addressing a specific subject on two pages. Evidently, the depth at which each contribution can describe the subject matter is limited and a full review of their statuses, advances, challenges and perspectives cannot be fully accomplished. Also, magnetism, as a vibrant research field, is too diverse, so that a number of areas will not be adequately represented here, leaving space for further Roadmap editions in the future. However, this 2017 Magnetism Roadmap article can provide a frame that will enable the reader to judge where each subject and magnetism research field stands overall today and which directions it might take in the foreseeable future. The first material focused pillar of the 2017 Magnetism Roadmap contains five articles, which address the questions of atomic scale confinement, 2D, curved and topological magnetic materials, as well as materials exhibiting unconventional magnetic phase transitions. The second pillar also has five contributions, which are devoted to advances in magnetic characterization, magneto-optics and magneto-plasmonics, ultrafast magnetization dynamics and magnonic transport. The final and application focused pillar has four contributions, which present non-volatile memory technology, antiferromagnetic spintronics, as well as magnet technology for energy and bio-related applications. As a whole, the 2017 Magnetism Roadmap article, just as with its 2014 predecessor, is intended to act as a reference point and guideline for emerging research directions in modern magnetism.

We developed a new one-pot synthesis method for realizing silver coated magnetite nanocomposite by way of a modified polyol process. In this reaction, polyethylene glycol was used as a solvent media and it was observed to play a key role to act as a reducing agent, stabilizer as well as a linker for silver coating simultaneously. Further, we could successfully transfer the phase from Fe3O4/Ag to α-Fe/Ag by using the annealing system at 600 °C in presence of hydrogen gas. X-ray diffraction data was independently used to confirm the formation of both the phases of Fe3O4/Ag and α-Fe/Ag. These Fe3O4/Ag and α-Fe/Ag samples were also characterized using transmission electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy techniques and compared the results with those of seed Fe3O4 nanoparticles. The magnetic properties of the composites, Fe3O4/Ag and α-Fe/Ag with different Ag concentrations, along with the seed Fe3O4 nanoparticles were measured using vibrating sample magnetometer (VSM) at room temperature. Maximum magnetization values of 61.3 emu/g and 175.1 emu/g were observed for the samples with 1 mL Ag concentrations of Fe3O4/Ag and α-Fe/Ag, respectively. This new synthesis method looks to be a promising route for facile synthesis of different magnetic nanocomposites suitable for bioapplications.

A facile sono-thermal approach using inexpensive and non-toxic chemicals was applied for the large-scale synthesis of iron nitride/iron (Fe4N/Fe) nanocomposite. The as-synthesized iron oxide (Fe3O4) nanoparticles by sonochemical method were treated in a thermal annealing chamber in presence of hydrogen (H2) and ammonia (NH3) gases to obtain Fe4N/Fe nanocomposite. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses revealed that the Fe4N/Fe nanocomposite had been successfully synthesized using this simple method. Transmission electron microscopy (TEM) data demonstrated that the sizes of the as-synthesized Fe4N/Fe nanocomposite were larger compared to the sizes for the initial Fe3O4 NPs. The magnetization curve obtained using vibrating sample magnetometer (VSM) measurements showed that the magnetization had been significantly increased in the synthesized Fe4N/Fe nanocomposite compared to that in the freshly-prepared Fe3O4 magnetic NPs.

Amorphous titania coated magnetite (Fe3O4/TiO2) nanocubes were successfully synthesized through hydrolysis and condensation of titanium isopropoxide and iron sulfate heptahydrate using single reaction sonochemical process for catalytic applications. X-ray diffractometry, transmission electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy were used to characterize the crystal structure, size and morphology, elemental composition, metal–metal and metal–oxygen bonds of the core/shell nanocubes. Magnetic properties of the samples were measured by a vibrating sample magnetometer at room temperature. Catalytic measurements on the samples showed an excellent efficiency for the degradation of methylene blue, and this efficiency was further promoted remarkably by addition of hydrogen peroxide (H2O2) within only 5 min of reaction time in the absence of ultraviolet irradiation. Even after recycling the sample for six times, the introduced catalyst was found to retain as much as 90% initial efficiency. A possible reaction mechanism for the sonochemical deposition of titania on the surface of magnetite nanocubes and also for the degradation process of methylene blue by the introduced catalyst was discussed.

In this study, we fabricate an integrated microfluidic chip with a planar Hall effect (PHE) sensor for single magnetic bead detection. The PHE sensor was constructed with a junction size of 10 μm × 10 μm using a trilayer structure of Ta(3 nm)/NiFe(10 nm)/Cu(1.2 nm)/IrMn(10 nm)/Ta(3 nm). The sensitivity of the PHE sensor was 19.86 μV/Oe. A diameter of 8.18 μm magnetic beads was used, of which the saturation magnetization was ~2.1 emu/g. The magnetic susceptibility χ of these magnetic beads was calculated to be~0.14. The diluted magnetic beads solution was introduced to the microfluidic channel attributing a single bead flow and simultaneously the PHE sensor voltage was measured to be 0.35 μV. The integrated microchip was able to detect a magnetic moment of 1.98 × 10 ?10 emu.

Recently microfluidic manipulation of live cell has been attracting attention because it is necessary for fast and accurate bioassays of cells within miniaturized devices like a lab-on-a-chip. This work concerns the alignment, translocation and concentration of live cells in a microfluidic channel by utilizing an ultrasonic standing wave. Among many ultrasonic manipulation methods, the technique using frequency swept ultrasound which was proposed in a previous study offers excellent particle manipulation performance, but that has been demonstrated only for biocompatible polystyrene microspheres with several different diameters, not actual biological cells. However, the technique needs to be verified for real cells because sizes and properties are little different with each other. Thus, in this work, the feasibility of using the ultrasonic frequency sweep method to manipulate live Nb2-11 cells was investigated experimentally The cells were aligned in a plane, moved to one side of a channel, and finally filtered out by sending them to one outlet with ultrasound. The frequency region of the applied ultrasound was between 1.75 MHz and 3.05 MHz. From experimental results, the cell behavior showing perfect alignment, almost perfect translocation and hence considerable aggregation proved the feasibility of using the frequency sweep method though the force acting on the Nb2-11 cells are much smaller than the force acting on polystyrene beads due to the differences in their sizes and mechanical properties.

We developed a new one-pot synthesis method for silica coated magnetite nanoparticles by way of a cheap- modified polyol process. In this reaction, polyethylene glycol was used as a solvent media and it has been found to play a key role to act as a reducing agent, stabilizer as well as a linker for silica coating, simultaneously. The Fe3O4/SiO2 sample prepared by this new method was compared with other seed Fe3O4 and Fe3O4/SiO2 samples synthesized through the modified Stober method and characterized using different analysis techniques such as transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The magnetic properties of the seed Fe3O4 and silica coated magnetite nanoparticles were studied by vibrating sample magnetometer at room temperature. The produced composite sample showed excellent stability against oxidation when annealed at 600 °C in presence of hydrogen gas. Thus, the facile new polyol process adopted in our study appears to be a promising route for synthesis of highly stable, hydrophilic silica coated magnetite nanoparticles.

International audience; The ability to stabilize the sensitivity of a magnetoresistance sensor in unstable thermal environments is a key parameter in many high precision measurements. Here, we propose a method to stabilize the sensitivity of a highly sensitive and low noise magnetic sensor based on a planar Hall Effect crossed junction. The stability is achieved by controlling the interplay between Zeeman energy, exchange bias energy, and anisotropy energy as a function of the temperature of the sensor stack comprising a trilayer structure NiFe/Cu/IrMn (10/0.12/10 nm). The high thermal stability of the sensor sensitivity of 4.5 ± 0.15 × 10−3 V/A/T/K is achieved when the external magnetic field is set around ±2 ± 0.04 mT and the applied current is fixed at 20 mA in the temperature range of 110 K–360 K. This method improves the magnetic sensor detection by about an order of magnitude, enabling its deployment in various research fields, particularly to study magnetic properties of small quantities of magnetic materials toward the detection of single magnetic objects, which was impossible before.