The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization ...orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.
Recent studies indicate that intestinal oxidative stress and microbiota imbalance is involved in weaning-induced intestinal dysfunction in piglets. We have investigated the effect of feeding a ...carvacrol-thymol blend supplemented diet on intestinal redox status, selected microbial populations and the intestinal barrier in weaning piglets. The piglets (weaned at 21 days of age) were randomly allocated to two groups with six pens per treatment and 10 piglets per pen. At weaning day (21 days of age), six piglets were sacrificed before weaning to serve as the preweaning group. The weaned group was fed with a basal diet, while the weaned-CB group was fed with the basal diet supplemented with 100 mg/kg carvacrol-thymol (1 : 1) blend for 14 days. On day 7 post-weaning, six piglets from each group were sacrificed to determine intestinal redox status, selected microbial populations, messenger RNA (mRNA) transcript levels of proinflammatory cytokines and biomarkers of intestinal barrier function. Weaning resulted in intestinal oxidative stress, indicated by the increased concentration of reactive oxygen species and thiobarbituric acid-reactive substances present in the intestine. Weaning also reduced the population of Lactobacillus genus and increased the populations of Enterococcus genus and Escherichia coli in the jejunum, and increased mRNA levels of tumor necrosis factor α (TNF-α), interleukin 1β and interleukin 6 (IL-6). In addition, decreased mRNA levels of zonula occludens and occludin in the jejunal mucosa and increased plasma diamine oxidase concentrations indicated that weaning induced dysfunction of the intestinal barrier. On day 7 post-weaning, supplementation with the carvacrol-thymol blend restored weaning-induced intestinal oxidative stress. Compared with the weaned group, the weaned-CB group had an increased population of Lactobacillus genus but reduced populations of Enterococcus genus and E. coli in the jejunum and decreased mRNA levels of TNF-α. The results indicated that weaning induced intestinal oxidative stress and dysfunction of the intestinal barrier. Dietary supplementation with 100 mg/kg carvacrol-thymol (1 : 1) decreased the intestinal oxidative stress and influenced selected microbial populations without changing the biomarkers of intestinal barrier in weaning piglets.
Nanometer-thick passive films, which impart superior corrosion resistance to metals, are degraded in long-term service; they are also susceptible to chloride-induced localized attack. Here we show, ...by engineering crystallographic configurations upon metal matrices adjacent to their passive films, we obtain great enhancement of corrosion resistance of FeCr15Ni15 single crystal in sulphuric acid, with activation time up to two orders of magnitude longer than that of the non-engineered counterparts. Meanwhile, engineering crystallography decreases the passive current density and shifts the pitting potential to noble values. Applying anodic polarizations under a transpassivation potential, we make the metal matrices underneath the transpassive films highly uneven with {111}-terminated configurations, which is responsible for the enhancement of corrosion resistance. The transpassivation strategy also works in the commercial stainless steels where both grain interior and grain boundaries are rebuilt into the low-energy configurations. Our results demonstrate a technological implication in the pretreatment process of anti-corrosion engineering.
Dipolarization fronts (DFs) are frequently detected in the Earth's magnetotail from XGSM = −30 RE to XGSM = −7 RE. How these DFs are formed is still poorly understood. Three possible mechanisms have ...been suggested in previous simulations: (1) jet braking, (2) transient reconnection, and (3) spontaneous formation. Among these three mechanisms, the first has been verified by using spacecraft observation, while the second and third have not. In this study, we show Cluster observation of DFs inside reconnection diffusion region. This observation provides in situ evidence of the second mechanism: Transient reconnection can produce DFs. We suggest that the DFs detected in the near‐Earth region (XGSM > −10 RE) are primarily attributed to jet braking, while the DFs detected in the mid‐ or far‐tail region (XGSM < −15 RE) are primarily attributed to transient reconnection or spontaneous formation. In the jet‐braking mechanism, the high‐speed flow “pushes” the preexisting plasmas to produce the DF so that there is causality between high‐speed flow and DF. In the transient‐reconnection mechanism, there is no causality between high‐speed flow and DF, because the frozen‐in condition is violated.
Key Points
DFs are observed inside reconnection diffusion region
Three formation mechanisms of DF are compared
Causality between flow and DF is discussed
The range of potential applications of compact laser-plasma ion sources motivates the development of new acceleration schemes to increase achievable ion energies and conversion efficiencies. Whilst ...the evolving nature of laser-plasma interactions can limit the effectiveness of individual acceleration mechanisms, it can also enable the development of hybrid schemes, allowing additional degrees of control on the properties of the resulting ion beam. Here we report on an experimental demonstration of efficient proton acceleration to energies exceeding 94 MeV via a hybrid scheme of radiation pressure-sheath acceleration in an ultrathin foil irradiated by a linearly polarised laser pulse. This occurs via a double-peaked electrostatic field structure, which, at an optimum foil thickness, is significantly enhanced by relativistic transparency and an associated jet of super-thermal electrons. The range of parameters over which this hybrid scenario occurs is discussed and implications for ion acceleration driven by next-generation, multi-petawatt laser facilities are explored.
We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor νover ¯_{e} inverse β decay candidates observed over 1958 days ...of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative νover ¯_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the inverted hierarchy.
The effects of microstructure on crack resistance and toughening mechanism of an ultra-low carbon steel were investigated. The microstructures were controlled via thermal-mechanical control ...processing (TMCP) and heat-treatments. Distribution of stress concentration, microcracks formation and propagation during Charpy impacting were investigated in detail. The results indicate that the lath martensitic structure provided a higher yield stress together with a better impact property, compared to the polygonal ferritic structure. The high strength can be attributed to the high density of dislocations in the lath martensitic structure introduced by quenching. The instrumented Charpy impact results indicated that the crack initiation energy in the lath martensitic structure was similar to that in the ferritic structure while the crack propagation energy was significantly greater than that in the ferritic structure, leading to the high toughness of the steel with the lath martensitic structure. Local stress concentration distributed uniformly in lath martensitic structure, leading to the homogeneous nucleation of microcrack. The high crack propagation energy in the lath martensitic structure can be attributed to the high fraction of high angle grain boundaries and fine effective grains, which deflected the cleavage crack propagation direction.
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•60 °C decrement in DBTT was obtained through controlling microstructure.•The lath martensite provides a good combination of strength and toughness.•The high crack propagation energy of lath martensite benefits to the good toughness.•HAGB and EGS deflect the cleavage crack propagation direction.
We demonstrate that a giant spin Hall effect (SHE) can be induced by introducing a small amount of Bi impurities in Cu. Our analysis, based on a new three-dimensional finite element treatment of spin ...transport, shows that the sign of the SHE induced by the Bi impurities is negative and its spin Hall (SH) angle amounts to -0.24. Such a negative large SH angle in CuBi alloys can be explained by applying the resonant scattering model proposed by Fert and Levy Phys. Rev. Lett. 106, 157208 (2011) to 6p impurities.
A low level of CD4+ lymphocyte cells makes end-stage HIV/AIDS patients highly susceptible to microbial infections. We have adopted the next generation sequencing method to identify the spectrum of ...bacterial plasma and viral elements that might be present in these patients. The HIV/AIDS plasma microbiome was dominated by bacterial elements in the taxonomical order Pseudomonadales, while healthy people carried fewer bacterial DNA in the plasma. We have found that many of the bacterial elements in HIV/AIDS plasma are similar to those of the microbes found in the human gut, suggesting potential acquisition of microbial elements from the gut. The HIV/AIDS and normal plasma DNA virome shared some similarities in the presence of common ubiquitous eukaryotic viruses. The normal DNA virome was mainly composed of viruses from Anelloviridae. In contrast, the HIV/AIDS DNA virome contained a large proportion of bacteriophages, endogenous retroviruses and a non-human virus. In addition, several sequences, which might belong to novel bacteria or endogenous retroviruses, were identified. Taken together, the use of high-throughput sequencing technology in unveiling microbial metagenomics may facilitate future research in combating HIV/AIDS and its associated microbial complications.
The molecular mechanism underlying gastric cancer (GC) invasion and metastasis is still poorly understood. In this study, we tried to investigate the roles of CXCR4 and CXCR2 signalings in gastric ...cancer metastasis. A highly invasive gastric cancer cell model was established. Chemokines receptors were profiled to search for the accountable ones. Then the underlying molecular mechanism was investigated using both in vitro and in vivo techniques, and the clinical relevance of CXCR4 and CXCR2 expression was studied in gastric cancer samples. CXCR4 and CXCR2 were highly expressed in a high invasive gastric cancer cell model and in gastric cancer tissues. Overexpression of CXCR4 and CXCR2 was associated with more advanced tumor stage and poorer survival for GC patients. CXCR4 and CXCR2 expression strongly correlated with each other in the way that CXCR2 expression changed accordingly with the activity of CXCR4 signaling and CXCR4 expression also changed in agreement with CXCR2 activity. Further studies demonstrated CXCR4 and CXCR2 can both activated NF-κB and STAT3 signaling, while NF-κBp65 can then transcriptionally activate CXCR4 and STAT3 can activate CXCR2 expression. This crosstalk between CXCR4 and CXCR2 contributed to EMT, migration and invasion of gastric cancer. Finally, Co-inhibition of CXCR4 and CXCR2 is more effective in reducing gastric cancer metastasis. Our results demonstrated that CXCR4 and CXCR2 cross-activate each other to promote the metastasis of gastric cancer.
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