Search

On-Load Tap-Changer (OLTC) is the only core equipment in the ultra-high voltage (UHV) converter transformer that moves frequently, and flexible connection structure (FCS) is the moveable actuating part of the vacuum interrupter drive mechanism of OLTC. Minimizing the transient stress during the movement of FCS is essential for prolonging its fatigue life, thus is pursued by optimizing the shape of the flexible sheet in this paper. Peak transient stress of FCS is defined as the optimization objective, and eight geometrical parameters controlling the shape of flexible sheet are defined as the optimization variables. A progressive three-stage shape optimization strategy is proposed by combing four techniques: Multi-body Dynamic (MBD), Finite Element Analysis (FEA), Correlation Coefficient Analysis (CCA) and Adaptive Single-objective Optimization (ASO). MBD analysis of the vacuum interrupter drive mechanism and FEA of the FCS are utilized for calculating the transient stress distribution. Spearman CCA is performed to quantitively determine the correlation and sensitivity between the optimization variables and the optimization objective. Shape optimization of FCS using ASO is carried out, and results show that the stress concentration is basically eliminated and the peak transient stress decrease by 34.35% after shape optimization. Further analysis of the FCS with multi-layered flexible sheet is conducted, again demonstrating the effectiveness of the shape optimization on minimizing transient stress.

Abstract Determining the associated relationship of genotype and phenomenon would benefit the understanding of disease and renew disease intervention means. 14,518 patients who underwent haemoglobin electrophoresis from June 2020 to December 2020 were enrolled in our study, and additional data including sex, age and routine blood examination results were collected. We focused on individuals with normal red blood cell indices and no common thalassemia pathogenic mutation and selected three groups for the following study: the control group (2.5% ≤ HbA2 ≤ 3.5%), the HbA2 under 2.5 group (HbA2

Two-dimensional electron gases that form in some complex oxide heterostructures may have useful functional behavior due to the interaction of the parent materials. Here the authors show that PZT/STO interfaces can host a spin-polarized electron gas, even though the bulk materials are nonmagnetic.

Emergent physical properties often arise at interfaces of complex oxide heterostructures due to the interplay between various degrees of freedom, especially those with polar discontinuities. It is desirable to explore if these structures may generate pure and controllable spin currents, which are needed to attain unmatched performance and energy efficiency in the next-generation spintronic devices. Here we report the emergence of a spin-polarized two-dimensional electron gas (SP-2DEG) at the interface of two insulators, SrTiO3 and PbZr0.2Ti0.8O3. This SP-2DEG is strongly localized at the interfacial Ti atoms, due to the interplay between Coulomb interaction and band bending, and can be tuned by the ferroelectric polarization. Our findings open a door for engineering ferroelectric/insulator interfaces to create tunable ferroic orders for magnetoelectric device applications and provide opportunities for designing multiferroic materials in heterostructures. [ABSTRACT FROM AUTHOR]

Although monitoring and diagnosis of fetal diseases in utero remains a challenge, metabolomics may provide an additional tool to study the etiology and pathophysiology of fetal diseases at a functional level. In order to explore specific markers of fetal disease, metabolites were analyzed in two separate sets of experiments using amniotic fluid from fetuses with Down syndrome (DS) as a model. Both sets included 10‑15 pairs of controls and cases, and amniotic fluid samples were processed separately; metabolomic fingerprinting was then conducted using UPLC‑MS. Significantly altered metabolites involved in respective metabolic pathways were compared in the two experimental sets. In addition, significantly altered metabolic pathways were further compared with the genomic characters of the DS fetuses. The data suggested that metabolic profiles varied across different experiments, however alterations in the 4 metabolic pathways of the porphyrin metabolism, bile acid metabolism, hormone metabolism and amino acid metabolism, were validated for the two experimental sets. Significant changes in metabolites of coproporphyrin III, glycocholic acid, taurochenodeoxycholate, taurocholate, hydrocortisone, pregnenolone sulfate, L‑histidine, L‑arginine, L‑glutamate and L‑glutamine were further confirmed. Analysis of these metabolic alterations was linked to aberrant gene expression at chromosome 21 of the DS fetus. The decrease in coproporphyrin III in the DS fetus may portend abnormal erythropoiesis, and unbalanced glutamine‑glutamate concentration was observed to be closely associated with abnormal brain development in the DS fetus. Therefore, alterations in amniotic fluid metabolites may provide important clues to understanding the etiology of fetal disease and help to develop diagnostic testing for clinical applications. [ABSTRACT FROM AUTHOR]

Surface textures are increasingly studied for improving the tribological performances of bearing systems, however, less attention has been paid to their influences on high-speed bearings. This paper invesgates the tribological behaviours of concave textures with different geometric structures, such as various depths, aspect ratios and shapes, under high speed conditions. Some interesting results are drawn out. Only well-designed surface texture could improve the tribological performances of high-speed bearings. This work could provide a valuable guide for the design of surface texture in high-speed bearings. [ABSTRACT FROM AUTHOR]

The influence of annealing time and annealing temperature under controlled partial pressure of selenium on the in-plane electrical transport properties of specimens of [(PbSe)0.99]1[WSe2]1 turbostratic nanolaminates was studied. The annealing treatments were found to be very effective in reducing carrier concentrations and improving carrier mobility in the annealed films, which is attributed to the reduction of compositional and structural defects. As a result, room temperature Hall mobilities greater than 60 cm² V-1s-1 are observed in spite of the small in-plane domain sizes (on the order of 10 nm) that are related to the turbostratic disorder. The technique appears promising for decreasing the concentration of kinetically trapped defects in these and related self-assembled nanostructures, a key challenge to evaluating the expected potential for controlling electrical and thermal transport properties via designed nanostructure in these and related materials. [ABSTRACT FROM AUTHOR]

We describe here a general synthesis approach for the preparation of new families of misfit layer compounds and demonstrate its effectiveness through the preparation of the first 64 members of the [(PbSe)0.99]m(WSe2)nfamily of compounds, where mand nare integers that were systematically varied from 1 to 8. The new compounds [(PbSe)1]m(WSe2)nwere synthesized by annealing reactant precursors containing mlayers of alternating elemental Pb and Se followed by nlayers of alternating elemental W and Se, in which the thickness of each pair of elemental layers was calibrated to yield a structural bilayer of rock salt structured PbSe and a trilayer of hexagonal WSe2. The compounds are kinetically trapped by the similarity of the composition profiles and modulation lengths in the precursor and the targeted compounds. The structural evolution from initial reactant of layer elements to crystalline misfit layer compounds was tracked using X-ray diffraction. The crystal structures of new compounds were probed using both analytical electron microscopy and X-ray diffraction. The c-axis of the misfit layer compound is perpendicular to the substrate, with a c-axis lattice parameter that changes linearly with a slope of 0.612−0.615 nm as mis changed and nis held constant and with a slope of 0.654−0.656 nm as nis varied and mis held constant. The in-plane lattice parameters did not change as the individual layer thicknesses were increased and a misfit parameter of y= −0.01 was calculated, the first negative misfit parameter among known misfit layer compounds. Analytical electron microscopy images and X-ray diffraction data collected on mixed hklreflections revealed rotational (turbostratic) disorder of the a−bplanes. [ABSTRACT FROM AUTHOR]

X-ray diffraction and imaging techniques at the Advanced Photon Source (APS) have been used to characterize PbSe/MoSe2 and PbSe/WSe2 thin films and multilayers. Diffraction measurements with area detectors were made to demonstrate the nanoscale coherence size of the layers both in-plane and perpendicular to the surface. Higher-resolution diffraction measurements that exploit the tunability of synchrotron radiation for anomalous scattering contrast have been used to accurately determine layer spacings in these multilayers. We also discuss opportunities in other new and emerging x-ray techniques, such as time-resolved studies during growth or processing, and present x-ray imaging capabilities that can be used to investigate thermoelectric thin-film materials. [ABSTRACT FROM AUTHOR]

The novel, partially filled compounds Ce xCo 4Ge 6Se 6were synthesized using two methods: low-temperature interdiffusion and nucleation of ultrathin elemental layers and a bulk, high-temperature technique. The compounds were characterized by differential scanning calorimetry, powder X-ray diffraction, and electron probe microanalysis. The lattice parameters for the samples synthesized using the high-temperature technique were calculated to be 8.30 Å, while the samples synthesized using the elemental deposition technique showed lattice expansion proportional to the amount of incorporated rare earth element, with lattice parameters ranging from 8.30 Å for x= 0 up to a lattice parameter of 8.34 Å for x= 0.2. Rietveld analysis on X-ray diffraction data for both sets of samples showed incorporation of the rare earth element into the interstitial site, up to 20% occupancy. [ABSTRACT FROM AUTHOR]

The in-plane thermal conductivity is measured to be three times lower in misfit-layered [(PbSe)0.99]x(WSe2)x superlattice thin films than disordered-layered WSe2 because of interface scattering despite a higher cross-plane value in the former than the latter. While having little effect on the in-plane thermal conductivity, annealing the p-type [(PbSe)0.99]2(WSe2)2 films in Se increases the in-plane Seebeck coefficient and electrical conductivity because of decreased defect and hole concentrations. Increasing interface density of the annealed films by decreasing x from 4 to 2 has weak influence on the in-plane thermal conductivity but increases the Seebeck coefficient and decreases the room-temperature electrical conductivity. [ABSTRACT FROM AUTHOR]

The targeted synthesis of multiple compounds with specific controlled nanostructures and identical composition is a grand challenge in materials chemistry. We report the synthesis of the new metastable compounds [(PbSe)1.00]m(MoSe2)n using precursors each designed to self-assemble into a specific compound. To form a compound with specific values for m and n, the number of atoms within each deposited elemental layer was carefully controlled to provide the correct absolute number of atoms to form complete layers of each component structural unit. On low-temperature annealing, these structures self-assemble with a specific crystallographic orientation between the component structural units with atomically abrupt interfaces. There is rotational disorder between the component structural units and between MoSe2 basal plane units within the MoSe2 layers themselves. The lead selenide constituent has a distorted rock salt structure exactly m bilayers thick leading to peaks in the off-axis diffraction pattern as a result of the finite size of and rotational disorder between the crystallites. The in-plane lattice parameters of the PbSe and MoSe2 components are independent of the value of m and n, suggesting little or no strain caused by the interface between them. These compounds are small band gap semiconductors with carrier properties dominated by defects and exhibit extremely low thermal conductivity as a result of the rotational disorder. The thermal conductivity can be tuned by varying the ratio of the number of ordered PbSe rock salt layers relative to the number of rotationally disordered MoSe2 layers. This approach, based on controlling the local composition of the precursor and low temperature to limit diffusion rates, provides a general route to the synthesis of new compounds containing alternating layers of constituents with designed nanoarchitecture. [ABSTRACT FROM AUTHOR]