Nanocrystalline Core Research Articles

Efficiency Characteristics of Loosely Coupled Transformer With Laminated Nanocrystalline Core Considering Nonlinear Factors Caused by Crushing and Compressing Process

Efficiency Characteristics of Loosely Coupled Transformer With Laminated Nanocrystalline Core Considering Nonlinear Factors Caused by Crushing and Compressing Process

In situ crystalline structure of the human eosinophil major basic protein-1.

Eosinophils are white blood cells that participate in innate immune responses and have an essential role in the pathogenesis of inflammatory and neoplastic disorders. Upon activation, eosinophils release cytotoxic proteins such as major basic protein-1 (MBP-1) from cytoplasmic secretory granules (SGr) wherein MBP-1 is stored as nanocrystals. How the MBP-1 nanocrystalline core is formed, stabilized, and subsequently mobilized remains unknown. Here, we report the in-situ structure of crystalline MBP-1 within SGrs of human eosinophils. The structure reveals a mechanism for intragranular crystal packing and stabilization of MBP-1 via a structurally conserved loop region that is associated with calcium-dependent carbohydrate binding in other C-type lectin (CTL) proteins. Single-cell and single-SGr profiling correlating real-space three-dimensional information from cellular montage cryo-electron tomography (cryo-ET) and microcrystal electron diffraction (MicroED) data obtained from non-activated and IL33-activated eosinophils revealed activation-dependent crystal expansion and extrusion of expanded crystals from SGr. These results suggest that MBP-1 crystals play a dynamic role in the release of SGr contents. Collectively, this research demonstrates the importance of in-situ macromolecular structure determination.

Vibration and Noise Characteristics of Nanocrystalline Cores Under High-Frequency and Non-Sinusoidal Excitation

Vibration and Noise Characteristics of Nanocrystalline Cores Under High-Frequency and Non-Sinusoidal Excitation

Unravelling the development of preferred crystallographic orientation in dual-phase amorphous/nanocrystalline Zr-V thin films

Dual-phase amorphous/nanocrystalline alloys have been proven to present enhanced properties compared to their amorphous or nanocrystalline single-phase counterparts. These dual-phase materials are typically composed of nanocrystalline cores embedded in an amorphous matrix. In contrast, a new kind of dual-phase metallic films has recently been reported in which cone-shaped crystalline regions evolve as a result of competitive growth between the amorphous and crystalline phases with increasing film thickness. Here, we demonstrate that, unlike typical dual-phase alloys, Zr-V thin films exhibiting crystalline/amorphous competitive growth develop a preferred crystallographic orientation upon growth. Relying on pole figure observations, we uncover the development of a preferred orientation of the (110) crystallographic planes in the growth direction of the film with increasing film thickness. High-resolution transmission electron microscopy analysis reveals that the crystalline regions are formed by nano-branches which grow (110)-oriented. Based on this result, together with scanning and transmission electron microscopy observations, we associate the development of the thickness-dependent preferred orientation to the impingement between cone-shaped crystalline regions. This process triggers a selective growth mechanism that favors the selection of nano-branches growing near the direction of film growth. Our results and analyses provide a step forward in understanding the growth kinetics of dual-phase alloys presenting complex microstructures.

Decoupled dual‐channel loosely coupled transformer with hybrid nanocrystalline and ferrite core for current sharing of modular wireless power transfer system

AbstractCross‐coupling and current sharing are the main problems faced by modular wireless power transfer (WPT) systems for electric vehicle (EV) applications. In this study, a decoupled dual‐channel wireless power transfer loosely coupled transformer (LCT) with a hybrid core composed of nanocrystalline and ferrite is proposed for modular WPT systems, as well as WPT systems with specific hybrid topology or detuned compensation. Firstly, the requirements of the LCT for modular parallel dual‐channel WPT system and detuned compensation are discussed. For these requirements, the structure and corresponding optimization design method of the decoupled dual‐channel LCT with a hybrid core is then proposed, and an LCT is designed with this method for the case study. Furthermore, the LCT is analysed by the finite element method (FEM). It is revealed that the mutual inductances of the proposed LCT between transmitting and receiving coils can be symmetrical under misalignment in multiple directions, while the cross‐coupling is eliminated. Finally, the designed LCT is manufactured and verified in a modular parallel dual‐channel WPT system. The experimental results show that the current and power sharing is realized under misalignment in multiple directions.

Preparing bulk nanocrystalline Cu–Al alloys via rotary swaging

Although nanocrystalline (NC) metals and alloys have been studied for nearly 40 years, their preparation is limited to the laboratory as large-scale; low-cost commercial production remains a challenge. In this study, high-strength bulk NC Cu–Al alloys were prepared from coarse-grained Cu–Al alloy rods via rotary swaging. Rotary swaging is characterized by the low cost and infinite length of the processed samples; therefore, it can advance the industrial application of bulk NC alloys. Core–shell-structured Cu–Al alloy rods with a hard NC core (diameter of 2.2 mm) wrapped in a soft ultrafine-grained (UFG) shell with a thickness of 1.75 mm were prepared using a rotary swage. Tensile tests revealed that the hard NC Cu–Al alloy core exhibited an ultimate tensile strength of 1034 MPa, which surpassed current strength records. Microstructural characterization showed that the hard NC core was composed of NC fiber grains with widths of 45 nm and lengths of 190 nm. The edge of the rod contained numerous low-angle grain boundaries and shear bands, which provided it with a lower strength and higher elongation than those of the center. During swaging, strong (200) and (111) fiber textures perpendicular to the cross-section were produced during the early stages of deformation. In the latter deformation stages, the polar densities of the (200) and (111) textures weakened, and some complex textures were formed along with high-angle grain boundaries. The grain refinement mechanisms were dominated by multiple deformation twinning, stacking faults, and dislocation slips. Finite elemental analysis showed that triaxial compressive stress and a high strain rate were applied to grain refinement. In addition, the softer shell protects the harder core during deformation, preventing fracture. This study verified an effective preparation technique for bulk NC materials via rotary swaging because it is a simple process with low cost and broad industrial prospects.

Review on Vesicular Drug Delivery System: Aquasomes

A special surface modification approach serves as a basis for a colloidal drug delivery system (CDDS) that helps to preserve the surface's constraining function. An aquasome is a submicronic structure (diameter 60-300nm). In order to create a medication delivery method other than liposome technology, they attracted a lot of attention in an effort to resolve issues with these vesicles' stability in biological fluids. Pharmaceuticals are absorbed by the aquasome, a molecular carrier made of a ceramic core (colloidal precipitation) to which glassy carbohydrates are subsequently permitted to adsorb as a nanometer-thick surface coating. Pharmaceuticals and other biochemically reactive surface members with non-covalently attached immobilized elements are stabilized by the carbohydrate coating, which also serves as a dehydroprotectant. These are nanoparticulate carrier systems but instead of being simple nanoparticles these are three layered self-assembled structures, comprised of a solid phase nanocrystalline core coated with oligomeric film to which biochemically active molecules are adsorbed with or without modification. These structures are self-assembled by non-covalent and ionic bonds. A large number of In vitro and animal model studies have been used to investigate the physical characteristics of this enabling system. It can be used as a carrier for vaccinations, hemoglobin, medications, dyes, enzymes, and even genetic material, giving it a very broad range of applications.

Aquasomes: an updated review

Aquasomes are circular particles that serve as nano particulate carrier systems, consisting of a solid phase nanocrystalline core coated in an oligomeric film. These three-layered self-assembled structures, ranging from 60 to 300 nanometers in size, allow direct or indirect absorption of biochemically active molecules. Aquasomes can be loaded with large amounts of agents through entropic, van der Waals, and ionic forces due to their size and active surface area. They display colloidal physical characteristics in an aqueous medium and are effective in distributing insulin, hemoglobin, serratiopeptidase, and poorly water-soluble medications.eramic nanoparticles, also known as aquasomes, are spherical particles that self-assemble into nanoparticulate carriers, resembling water bodies. These self-assembled structures are effective in the distribution of hemoglobin, insulin, and enzymes like serratiopeptidase. In this abstract, we will cover a review on Aquasomes.

High-frequency loss modeling of nanocrystalline core considering nonuniform distribution of flux density

Nanocrystalline core is widely used in the design process of high-frequency transformers and inductors due to the attractive magnetic properties of nanocrystalline material. However, the flux density distribution is nonuniform in the core because the reluctance is closely related to its geometric shape. The nonuniformity of flux density distribution may cause huge calculation errors of core losses. In this paper, Finite Element Method (FEM) is used to justify taking into account nonuniform distribution of flux density during the process of core loss calculation. An improved loss separation equation considering nonuniform distribution of flux density is proposed, and the improved equation is verified through calculating and analyzing the losses of nanocrystalline cores with different wound thicknesses. Compared with the traditional loss separation equation, the accuracy is improved, and the average error of improved equation is confined in 10%.

Toroidal seawater conductivity sensors and instrumentation for anti-submarine warfare

This paper describes the development of toroid-based seawater conductivity sensors and instrumentation for 0 to 60 mS/cm conductivity range and 50 bar hydrostatic pressure operational capability which is equivalent to 500 metres of ocean depth. Double core toroidal transformer concept was used and investigated for Mn-Zn and Fe based nanocrystalline cores, turns ratio and temperature dependence. Different excitation and sense coil turn numbers were fabricated by keeping the turn’s ratio 1:2, 1:4, 1:6 and 1:8. Optimum frequency of Mn-Zn based conductivity sensors with lower and higher turn numbers were observed for turn ratio 1:8 and 1:4 respectively at 120 kHz and obtained voltage responses of 952 and 1567 mV. Fe based Nano crystalline core with turn ratio 1:8 shows an optimum frequency of 70 kHz and giving a voltage difference of 830 mV. Two dimensional polynomials of order 2 were presented for temperature dependence of conductivity for Mn-Zn core based sensors. Sensor responses of Fe based nanocrystalline core sensors in ‘lower turn number’ configuration with same turn ratio is presented and observed linear temperature dependence compared to Mn-Zn based sensors. The mechanical design and frequency of operation of developed conductivity sensors gives inherent immunity to ASW band of frequency interference. The efficacy of conductivity sensor with measuring electronics and commercial standard sensors profiling was proved experimentally compared up to 500 metres in sea profiling and obtained a root mean square error of 0.42 for profile data.

Homogenization Technique of Nanocrystalline Cores Considering the Inter-Laminar Eddy Currents due to Inter-Layer Contact

Homogenization Technique of Nanocrystalline Cores Considering the Inter-Laminar Eddy Currents due to Inter-Layer Contact

Loss Analysis of Nanocrystalline Cores for High Frequency Transformer in Power Electronics Circuits

Loss Analysis of Nanocrystalline Cores for High Frequency Transformer in Power Electronics Circuits

Design and implementation of a Central-Tapped Medium Frequency Transformer with nanocrystalline core for high-efficiency DC-DC SAB converters

A design methodology for medium frequency transformers, which considers a central tap in its secondary winding, is thoroughly presented in this paper. Topologies such as SAB (Single-Active Bridge), PSFB (Phase Shift Full Bridge), and DAB (Dual Active Bridge) can be implemented using this type of transformer for nowadays applications. The design and implementation of a Central-Tapped Medium Frequency Transformer (CT-MFT) is carried out and it is tested as part of a SAB topology. Differently to other proposals, the equivalent model of the CT-MFT was thoroughly defined and verified in the simulation and a tailor-made design methodology is presented. As result, the CT-MFT prototype achieve 99.49 % efficiency which demonstrate the usefulness and efficacy of the proposed methodology. The experience gained in developing this advanced design procedure opens the possibility of further improving isolated unidirectional and bidirectional DC-DC converter topologies in aspects such as efficiency and reliability.

GaN-based cryogenic temperature power electronics for superconducting motors in cryo-electric aircraft

Climate change has spurred a shift to electric transportation, but aviation faces challenges with electric energy storage and propulsion. Cryogenically cooled superconducting motors, along with cryogenically cooled power electronics, offer a solution to increase the efficiency and power density of electric aircraft. This paper evaluates the feasibility of cryogenic power electronics by characterising new technologies (GaN, nanocrystalline) using new experimental techniques. It is found that the on resistance reductions of GaN E-high electron mobility transistors at cryogenic temperatures depend on the maximum blocking voltage of the device, and the size of the gate resistor for ohmic p-GaN devices. Different types of nanocrystalline cores are shown to vary greatly in their behaviour at cryogenic temperatures, which is measured using a modified core loss measurement circuit. Further analysis shows that the losses of a GaN based cryogenic inverter could potentially halve that of an equivalent Si based inverter.

A novel iron biomineralization on basaltic rocks from the Challenger Deep, southern Mariana Trench

The habitability of the hadal zone is not well understood and how microbes survive and adapt to this extreme environment is still largely unknown. Here we report the discovery of microbial biofilm that experience extensive Fe-mineralization on the surface of rocks from the Challenger Deep in the southern Mariana Trench. We found microbial biofilms of abundant globules internally permineralized by acicular goethite. The EDS analyses, combined with SEM and TEM, show that the globules are enriched in carbon and phosphorus, potentially indicating their biological origin. Cross sections of globules reveal a bilayer structure consisting of an acicular nano-crystalline core and a colloidal envelope. Vibrational spectroscopy reveals that this colloidal envelope is composed of EPS (extracellular polymeric substances). This mineralization is completely different from Fe-mineralization induced by all other known Fe-oxidizing bacteria, suggesting previously unknown interactions between Fe and microorganisms in hadal settings. Our findings highlight the significance of Fe-mineralization and its contributions to the ecosystem in hadal environments.

Superlattice-shelled nanocrystalline core structural design for highly sensitive GMI sensors

Giant magnetic impendence (GMI) sensors are known as a significant pillar of modern technology, and has many applications in smart society such as automation, navigation and bioengineering. Developing high-sensitive GMI sensors operating under extremely weak magnetic fields is highly desirable yet challenging. Here, we proposed superlattice-shelled nanocrystalline core structural design in the cobalt-based amorphous sensor-core microwires for the highly sensitive GMI sensors. Continuous Co-based amorphous microwires with a length up to thousands of meters and uniform diameter is first fabricated by a scalable modified Taylor–Ulitovsky method and then processed by the picosecond lasering heat treatment. As a result, the microwire exhibits a unique nanostructure consisting of ultrafine nanocrystalline cores surround by the thermal-stable Cr-rich superlattice shell, and hence circumferential magnetic domains of the higher density and intensity. The GMI sensors made from nanostructured Co-based microwires show a sensitivity up to 1743 mV/Oe, the maximum GMI ratio up to 78%, increasing the performance by up to twice and nine times respectively over the GMI sensor made from the amorphous counterpart, and a wide linear range of ± 70000 nT. The correlation between the microstructure, magnetic domain structure and GMI performance is also established and discussed in the nanostructured Co-based microwires. Furthermore, we demonstrate the successful application of the highly sensitive GMI sensor in geomagnetic communication to detect underground energy transmission metal pipes with a detection resolution down to pT-level weak magnetic fields.

Investigation on Losses with Various Emerging Core and Winding Materials in a High Frequency Planar Transformer

In this work, various emerging core and winding materials suitable for a high frequency planar transformer (PT) has been analyzed and compared. Core and winding materials used in a transformer has a significant effect mostly in the core and winding losses of the transformer. Emerging core materials like amorphous and nanocrystalline cores were compared against the conventional ferrite core. The results obtained showed that core losses were reduced by around 48.14% on using amorphous or nanocrystalline cores instead of the conventional ferrite cores. Typical copper and aluminum windings were also compared with emerging materials like carbon nanotube (CNT), Cu/CNT and Al/CNT. Winding losses was found to be the lowest on using CNT windings instead of metal windings like Cu or Al, or metals composite windings like Cu/CNT and Al/CNT. A winding loss reduction of about 56.2% was seen with CNT windings. Thus, it was concluded that the best possible core and winding combination was amorphous or nanocrystalline cores with CNT windings, as they give the lowest possible core and winding losses for the PT. Finite Element Analysis was carried out on a 2-kW PT operating at 100 kHz frequency, with the software Altair FLUX for the analysis.

Measurement and analysis of vibration characteristics of nanocrystalline magnetic core under symmetrical/asymmetrical waveforms

PurposeBecause the nanocrystalline core is widely used in power electronic equipment, and the excitation waveform of its working mode is complex, the vibration at medium and high frequencies cannot be ignored. Therefore, this study aims to study the vibration mechanism of nanocrystalline strip and the vibration characteristics of nanocrystalline magnetic ring under different excitation waveforms.Design/methodology/approachFirst, the electromagnetic vibration mechanism between nanocrystalline strips is analyzed by finite element analysis, and the force of the magnetic ring with and without air gap is compared and analyzed. Then, the vibration of nanocrystalline magnetic ring under different excitation waveforms such as sine wave, triangular wave, symmetric rectangular wave and asymmetric rectangular wave is analyzed by experimental method. The acceleration time domain waveform measured by the experiment is analyzed by fast Fourier transform, and the vibration is analyzed according to the spectrum.FindingsBecause of the increase of magnetic flux leakage, the volume force density and the Maxwell force on the surface of the nanocrystalline magnetic ring will increase after the air gap is opened, resulting in the intensification of vibration. Under symmetric/asymmetric rectangular wave excitation, the vibration acceleration varies with the duty cycle. Due to the influence of harmonic excitation, the relationship between the main frequency of vibration and the excitation frequency is not two times, and its multiple decreases with the increase of excitation frequency.Originality/valueThe research and analysis of this paper can promote the application of new magnetic materials in electrical equipment in small and medium-sized and medium- to high-frequency fields.

Estimation of Number of Cores for Preventing Common-Mode Inductor Saturation in Railway Traction Inverters

In the traction system of rolling stock, the common-mode (CM) voltage is over 500 V, so the inductors that suppress the CM current are prone to saturation. To prevent saturation, the traction inverter needs many numbers of cores inside CM inductors, but the required number of cores has been determined empirically. This paper proposes a method calculate the approximate number of nanocrystalline cores to avoid saturation of CM inductors in railway traction inverters without circuit simulation. Using the only the CM capacitance of traction motor and the core characteristics on the datasheet, the maximum flux density of the inductor is calculated. Comparing calculated results of the maximum flux density with the results measured with a 1500 V DC inverter indicates that the proposed method can better identify the occurrence of saturation than the methods based on CM current presented in the literature. Furthermore, for the entire CM voltage range from 500 V to 3000 V, the minimum number of cores which saturation is prevented by the proposed calculation method is shown to be in reasonable agreement with the simulation results.

Bidirectional Power Converter Module (PCM) for Advanced Vehicle Electrification

This research paper shows a Bidirectional Power converter Module (PCM) with an isolation transformer capable of performing diverse functionalities critical for vehicle electrification. The PCM is designed to enable Charging in systems involving grid-connected topologies for its regenerative capabilities, and bidirectional power flow functionality. This versatile converter is capable of giving various types of power outputs. Through modular configurations of PCMs, a wide range of voltage and power ratings can be achieved. The paper thoroughly elucidates the control algorithms for each operational mode, encompassing various grid functions. The simulation results aim to verify the performance of the converter. To attain high power density, the design incorporates SiC MOSFET power modules with high-frequency switching, complemented by an isolation transformer featuring a nanocrystalline core. In essence, this article presents a promising converter topology that provides many practical and relevant capabilities for the advancement of electric vehicles.