High sensitivity face shear magneto-electric composite array for weak magnetic field sensing

© 2020 Author(s). A magnetic field sensor is designed and fabricated using a piezoelectric face shear mode Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT)/Metglas magneto-electric (ME) composite. An outstanding ME coupling coefficient up to 1600 V/(cm Oe) was experimentally achieved, being ∼50% higher than the value from the extensional PMN-PT/Metglas ME composite with the same volume. The detection limit was found to be 2 × 10-6 Oe for the DC magnetic field, while it was 2 × 10-8 Oe for the AC magnetic field. The sensitivity of the face shear mode PMN-PT/Metglas ME composite is about one order of magnitude higher than that of a 32 extensional mode PMN-PT/Metglas based ME composite in sensing a weak DC magnetic field. A sensing array was also designed based on the ME composite to image weak DC magnetic fields, demonstrating a great potential promising for sensing weak magnetic fields

The dyadic self-care experience of stroke survivors and their caregivers: A qualitative descriptive study

background promoting self-care is the core response strategy of the global health system to the burden of stroke. although self-care in stroke represents a dyadic phenomenon, the dyadic self-care experience of stroke survivors and their caregivers is often overlooked in clinical practice. objectives the aim of this study was to explore the dyadic self-care experience of stroke survivors and their caregivers. design a descriptive qualitative design was used to conduct the study. results the consolidated criteria for reporting qualitative research was used for study reporting. a total of 21 stroke survivor-caregiver dyads were recruited for this study between may 2022 and september 2022. data were collected through semistructured interviews and analyzed using thematic analysis. In this study, four themes were identified: (1) poor relationship quality of the dyads, (2) dyadic incongruence in managing stroke, (3) a slow and tiring dyadic self-care process and (4) happy cooperation in coping with dyadic self-care. discussion and conclusion healthcare professionals should give greater consideration to the contradictions and disparities that may arise between stroke survivors and caregivers during the self-care process. It is crucial for them to provide personalized and tailored support and interventions that can assist these individuals in achieving a more optimal balance in their dyadic self-care. patient/public contribution patients were involved in the formulation of interview questions for this study. no members of the public were involved in this study

An optimized parameter design method of SiC/Si hybrid switch considering turn-off current spike

In order to reduce the switching loss of SiC MOSFET/Si IGBT (SiC/Si) hybrid switch, the switching mode that turn off the Si IGBT prior to the SiC MOSFET is generally adopted to achieved the zero-voltage switching operation of IGBT. The minority carrier in N-base region of the IGBT are recombined in the form of exponential attenuation due to the conductivity modulation effect. When the SiC MOSFET is turned off, if the carrier recombination process of the IGBT is not finished, it needs to bear a large collector–emitter voltage change rate, resulting in apparent current spike. This current spike will increase the current stress of the device and produce additional turn-off loss. The equivalent model of double pulse test circuit of SiC/Si hybrid switch considering parasitic parameters is established, and the turn-off transient process is given analytically. The influence of turn-off delay time, circuit parameters and working conditions on current spike are analysed quantitatively. Combined with the consideration of device stress and comprehensive turn-off loss, an optimized circuit design method of SiC/Si hybrid switch considering turn-off current peak is proposed, which provides theoretical and design guidance for high reliability and high efficiency SiC/Si-based converters

3D carbon allotropes: Topological quantum materials with obstructed atomic insulating phases, multiple bulk-boundary correspondences, and real topology

The study of topological phases with unconventional bulk-boundary correspondences and nontrivial real Chern number has garnered significant attention in the topological states of matter. Using the first-principle calculations and theoretical analysis, we perform a high-throughput material screening of the 3D obstructed atomic insulators (OAIs) and 3D real Chern insulators (RCIs) based on the Samara Carbon Allotrope Database (SACADA). Results show that 422 out of 703 3D carbon allotropes are 3D OAIs with multiple bulk-boundary correspondences, including 2D obstructed surface states (OSSs) and 1D hinge states, which are in one dimension and two dimensions lower than the 3D bulk, respectively. The 2D OSSs in these OAIs can be modified when subjected to appropriate boundaries, which benefits the investigation of surface engineering and the development of efficient topological catalysts. These 422 OAIs, which have 2D and 1D boundary states, are excellent platforms for multi-dimensional topological boundaries research. Remarkably, 138 of 422 OAIs are also 3D RCIs, which show a nontrivial real topology in the protection of spacetime inversion symmetry. Our work not only provides a comprehensive list of 3D carbon-based OAIs and RCIs, but also guides their application in various aspects based on multiple bulk-boundary correspondences and real topological phases

Ultrafast spin polarization in a multiferroic manganite BiFe0.5Mn0.5O3 thin film

In this work, we present observations of ultrafast carrier dynamics and spin polarization in a multiferroic manganite BiFe0.5Mn0.5O3 film excited by linearly and circularly polarized femtosecond pulses, respectively. The d-band charge transfer transition is reasonably assigned to Γ3 → Γ5. The transient reflectivity decay on a time scale as fast as only 0.3 ps is consistent with the picture of ultrafast electron-phonon coupling. The ultrafast switching of polarization ellipticity (\u3c 150 fs) originates from a transient coherent spin polarization by optical orientation. The ultrafast spin polarization switching is assigned to the Raman coherence process

Ag-Mg antisite defect induced high thermoelectric performance of α-MgAgSb

Engineering atomic-scale native point defects has become an attractive strategy to improve the performance of thermoelectric materials. Here, we theoretically predict that Ag-Mg antisite defects as shallow acceptors can be more stable than other intrinsic defects under Mg-poor-Ag/Sb-rich conditions. Under more Mg-rich conditions, Ag vacancy dominates the intrinsic defects. The p-type conduction behavior of experimentally synthesized ¿-MgAgSb mainly comes from Ag vacancies and Ag antisites (Ag on Mg sites), which act as shallow acceptors. Ag-Mg antisite defects significantly increase the thermoelectric performance of ¿-MgAgSb by increasing the number of band valleys near the Fermi level. For Li-doped ¿-MgAgSb, under more Mg-rich conditions, Li will substitute on Ag sites rather than on Mg sites and may achieve high thermoelectric performance. A secondary valence band is revealed in ¿-MgAgSb with 14 conducting carrier pockets

Production of Biodiesel Using a Vegetable Oil from Swida wilsoniana Fruits

Energy demand is increasing dramatically due to the fast industrial development, rising population, expanding urbanization, and economic growth in the world and large amount of fossil fuels are widely used. The depletion of fossil fuel reserves and the environmental pollution caused by burning of fossil fuels stimulate development of alternative fuels. Biodiesel today is the most popular and promising biofuel and vegetable oils are one of the potential feedstocks for biodiesel production. In order to explore the wild oil plant sources in China, the fruit oil of Swida wilsoniana, a wild woody oil plant widely distributed in the mountainous regions of calcareous sandstone, was used to produce the biodiesel by transesterification method. The reaction parameters were optimized by an orthogonal experimental design. The results showed that Swida wilsoniana fruit oil (SWO) could be conversed to biodiesel at a wide range of reaction conditions. The optimum conditions for the reaction process were determined as: methanol/oil mole ratio 5:1, catalyst dosage 1.1%, reaction temperature 60 °C, and reaction time 120 min. The characteristics of Swida wilsoniana biodiesel (SDBD) were analyzed, which was similar to that of 0# diesel. Moreover, SDBD has the advantages of higher flash point (>105) and lower ash content (<0.003). Therefore, SDBD is a safe and clean biodiesel and a promising alternative biofuel