Asymmetric magnetic bubble expansion under in-plane field in Pt/Co/Pt: effect of interface engineering

We analyse the impact of growth conditions on asymmetric magnetic bubble expansion under in-plane field in ultrathin Pt / Co / Pt films. Specifically, using sputter deposition we vary the Ar pressure during the growth of the top Pt layer. This induces a large change in the interfacial structure as evidenced by a factor three change in the effective perpendicular magnetic anisotropy. Strikingly, a discrepancy between the current theory for domain-wall propagation based on a simple domain-wall energy density and our experimental results is found. This calls for further theoretical development of domain-wall creep under in-plane fields and varying structural asymmetry.Comment: 16 pages, 3 figure

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

A nonlinear magnetoresistance - called unidirectional spin-Hall magnetoresistance - is recently experimentally discovered in metallic bilayers consisting of a heavy metal and a ferromagnetic metal. To study the fundamental mechanism of the USMR, both ferromagnetic and heavy metallic layer thickness dependence of the USMR are presented in a Pt/Co/AlOx trilayer at room temperature. To avoid ambiguities, second harmonic Hall measurements are used for separating spin-Hall and thermal contributions to the non-linear magnetoresistance. The experimental results are fitted by using a drift-diffusion theory, with parameters extracted from an analysis of longitudinal resistivity of the Co layer within the framework of the Fuchs-Sondheimer model. A good agreement with the theory is found, demonstrating that the USMR is governed by both the spin-Hall effect in the heavy metallic layer and the metallic diffusion process in the ferromagnetic layer

CFD investigation of blind-tee effects on flow mixing mechanism in subsea pipelines

Blind tees are widely used in subsea pipelines to enhance the mixing conditions of oil and gas products, but their structural design still relies on experience. In this paper, a series of numerical investigations have been carried out on blind-tee pipes in order to develop an in-depth understanding of their mixing mechanism and clarify the effects of blind-tee structures on the pipe flow. Firstly, the three-dimensional flow conditions in a typical blind tee have been simulated under different Reynolds numbers to investigate the mixing mechanism. Two critical Reynolds numbers for the vortex generations in blind tees are determined in the laminar flow regime, and the fitting curves of blind-tee vorticity dissipations are obtained. Then, the geometrical parameters, including the radial size ϕ, axial length (BSL) and position of the blind section, are varied systematically to study their effects on the flow characteristics and mixing conditions. The results indicate that increasing ϕ and BSL in an appropriate range can strengthen the flow circulation and promote the fluid exchange. Finally, an optimal configuration is obtained, which can improve the mixing capacity of blind tee by 53% in terms of the volume average vorticity as compared to the typical structure.publishedVersio

Halogen (F, Cl) concentrations and Sr-Nd-Pb-B isotopes of the basaltic andesites from the southern Okinawa Trough: implications for the recycling of subducted serpentinites

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(3), (2021): e2021JB021709, https://doi.org/10.1029/2021JB021709.Serpentinites are increasingly recognized as playing an important role in the global geochemical cycle. However, discriminating the contributions of serpentinites to arc magmas from those of other subduction components is challenging. The Okinawa Trough is a back-arc basin developed behind the Ryukyu subduction zone, where magmas are extensively affected by sediment subduction. In this study, we reported the F-Cl concentrations and Sr-Nd-Pb-B isotopes of basaltic andesites from the Yaeyama Graben, Yonaguni Graben, and Irabu Knoll in the southern Okinawa Trough. The Irabu Knoll lavas show the most enrichment of fluid-mobile elements and F ± Cl, and have the heaviest B isotopes (δ11B: +6.6 ± 1.5‰). They also have decoupled Sr-Nd isotopes: higher 87Sr/86Sr (∼0.7049) but have no obvious decrease of 143Nd/144Nd (∼0.5128). Results from slab dehydration modeling and mixing calculations suggest that the heavy δ11B in the Irabu Knoll lavas is not consistent with fluids derived from altered oceanic crust (AOC), sediments, or wedge serpentinites (formed in the mantle wedge), but rather from slab serpentinites (formed within the subducting plate); sediments control the subduction input of Nd, whereas the decoupled Sr-Nd isotopes are most likely due to the excess radiogenic Sr carried by AOC fluids. Our results imply that recycling of serpentinite fluids and AOC fluids are usually coupled in subduction zones, as the arc lavas influenced by subducted serpentinite generally show Sr-Nd isotopes decoupling. The large variation of Sr-Nd-B isotopes observed in a relatively localized area is consistent with a focused migration through the mantle wedge of components from multiple sources.This study was funded by the National Natural Science Foundation of China (91958213), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB42020402), the China Postdoctoral Science Foundation (2019M662454), the Shandong Provincial Natural Science Foundation, China (ZR2020QD068 and ZR2020MD068), the International Partnership Program of the Chinese Academy of Sciences (133137KYSB20170003), the Special Fund for the Taishan Scholar Program of Shandong Province (ts201511061), and the China Scholarship Council (201709410550).2021-09-1

Chiral magnetoresistance in Pt/Co/Pt zigzag wires

The Rashba effect leads to a chiral precession of the spins of moving electrons while the Dzyaloshinskii-Moriya interaction (DMI) generates preference towards a chiral profile of local spins. We predict that the exchange interaction between these two spin systems results in a 'chiral' magnetoresistance depending on the chirality of the local spin texture. We observe this magnetoresistance by measuring the domain wall (DW) resistance in a uniquely designed Pt/Co/Pt zigzag wire, and by changing the chirality of the DW with applying an in-plane magnetic field. A chirality-dependent DW resistance is found, and a quantitative analysis shows a good agreement with a theory based on the Rashba model. Moreover, the DW resistance measurement allows us to independently determine the strength of the Rashba effect and the DMI simultaneously, and the result implies a possible correlation between the Rashba effect, the DMI, and the symmetric Heisenberg exchange

A Lipoprotein Lipase–Promoting Agent, NO-1886, Improves Glucose and Lipid Metabolism in High Fat, High Sucrose–Fed New Zealand White Rabbits

The synthetic compound NO-1886 is a lipoprotein lipase activator that lowers plasma triglycerides and elevates high-density lipoprotein cholesterol (HDL-C). Recently, the authors found that NO-1886 also had an action of reducing plasma glucose in high-fat/high-sucrose diet–induced diabetic rabbits. In the current study, we investigated the effects of NO-1886 on insulin resistance and β-cell function in rabbits. Our results showed that high-fat/high-sucrose feeding increased plasma triglyceride, free fatty acid (FFA), and glucose levels and decreased HDL-C level. This diet also induced insulin resistance and impairment of acute insulin response to glucose loading. Supplementing 1% NO-1886 into the high-fat/high-sucrose diet resulted in decreased plasma triglyceride, FFA, and glucose levels and increased HDL-C level. The authors also found a clear increased glucose clearance and a protected acute insulin response to intravenous glucose loading by NO-1886 supplementation. These data suggest that NO-1886 suppresses the elevation of blood glucose in rabbits induced by feeding a high-fat/high-sucrose diet, probably through controlling lipid metabolism and improving insulin resistance

Enhancing Working Memory Based on Mismatch Negativity Neurofeedback in Subjective Cognitive Decline Patients: A Preliminary Study

Mismatch negativity (MMN) is suitable for studies of preattentive auditory discriminability and the auditory memory trace. Subjective cognitive decline (SCD) is an ideal target for early therapeutic intervention because SCD occurs at preclinical stages many years before the onset of Alzheimer's disease (AD). According to a novel lifespan-based model of dementia risk, hearing loss is considered the greatest potentially modifiable risk factor of dementia among nine health and lifestyle factors, and hearing impairment is associated with cognitive decline. Therefore, we propose a neurofeedback training based on MMN, which is an objective index of auditory discriminability, to regulate sensory ability and memory as a non-pharmacological intervention (NPI) in SCD patients. Seventeen subjects meeting the standardized clinical evaluations for SCD received neurofeedback training. The auditory frequency discrimination test, the visual digital N-back (1-, 2-, and 3-back), auditory digital N-back (1-, 2-, and 3-back), and auditory tone N-back (1-, 2-, and 3-back) tasks were used pre- and post-training in all SCD patients. The intervention schedule comprised five 60-min training sessions over 2 weeks. The results indicate that the subjects who received neurofeedback training had successfully improved the amplitude of MMN at the parietal electrode (Pz). A slight decrease in the threshold of auditory frequency discrimination was observed after neurofeedback training. Notably, after neurofeedback training, the working memory (WM) performance was significantly enhanced in the auditory tone 3-back test. Moreover, improvements in the accuracy of all WM tests relative to the baseline were observed, although the changes were not significant. To the best of our knowledge, our preliminary study is the first to investigate the effects of MMN neurofeedback training on WM in SCD patients, and our results suggest that MMN neurofeedback may represent an effective treatment for intervention in SCD patients and the elderly with aging memory decline

13.4 % Efficiency from All-Small-Molecule Organic Solar Cells Based on a Crystalline Donor with Chlorine and Trialkylsilyl Substitutions

How to simultaneously achieve both high open-circuit voltage (Voc) and high short-circuit current density (Jsc) is a big challenge for realising high power conversion efficiency (PCE) in all-small-molecule organic solar cells (all-SM OSCs). Herein, a novel small molecule (SM)-donor, namely FYSM−SiCl, with trialkylsilyl and chlorine substitutions was designed and synthesized. Compared to the original SM-donor FYSM−H, FYSM−Si with trialkylsilyl substitution showed a decreased crystallinity and lower highest occupied molecular orbital (HOMO) level, while FYSM−SiCl had an improved crystallinity, more ordered packing arrangement, significantly lower HOMO level, and predominant “face-on” orientation. Matched with a SM-acceptor Y6, the FYSM−SiCl-based all-SM OSCs exhibited both high Voc of 0.85 V and high Jsc of 23.7 mA cm−2, which is rare for all-SM OSCs and could be attributed to the low HOMO level of FYSM−SiCl donor and the delicate balance between high crystallinity and suitable blend morphology. As a result, FYSM−SiCl achieved a high PCE of 13.4 % in all-SM OSCs, which was much higher than those of the FYSM−H- (10.9 %) and FYSM−Si-based devices (12.2 %). This work demonstrated a promising method for the design of efficient SM-donors by a side-chain engineering strategy via the introduction of trialkylsilyl and chlorine substitutions

ERNIE-ViLG 2.0: Improving Text-to-Image Diffusion Model with Knowledge-Enhanced Mixture-of-Denoising-Experts

Recent progress in diffusion models has revolutionized the popular technology of text-to-image generation. While existing approaches could produce photorealistic high-resolution images with text conditions, there are still several open problems to be solved, which limits the further improvement of image fidelity and text relevancy. In this paper, we propose ERNIE-ViLG 2.0, a large-scale Chinese text-to-image diffusion model, which progressively upgrades the quality of generated images~by: (1) incorporating fine-grained textual and visual knowledge of key elements in the scene, and (2) utilizing different denoising experts at different denoising stages. With the proposed mechanisms, ERNIE-ViLG 2.0 not only achieves the state-of-the-art on MS-COCO with zero-shot FID score of 6.75, but also significantly outperforms recent models in terms of image fidelity and image-text alignment, with side-by-side human evaluation on the bilingual prompt set ViLG-300

Nodal and Nematic Superconducting Phases in NbSe2_2 Monolayers from Competing Superconducting Channels

Transition metal dichalcogenides like 2H-NbSe$_2$ in their two-dimensional (2D) form exhibit Ising superconductivity with the quasiparticle spins are firmly pinned in the direction perpendicular to the basal plane. This enables them to withstand exceptionally high magnetic fields beyond the Pauli limit for superconductivity. Using field-angle-resolved magnetoresistance experiments for fields rotated in the basal plane we investigate the field-angle dependence of the upper critical field (Hc$_2$), which directly reflects the symmetry of the superconducting order parameter. We observe a six-fold nodal symmetry superposed on a two-fold symmetry. This agrees with theoretical predictions of a nodal topological superconducting phase near Hc$_2$, together with a nematic superconducting state. We demonstrate that in NbSe$_2$ such unconventional superconducting states can arise from the presence of several competing superconducting channels