Antiferromagnetic magnonic charge current generation via ultrafast optical excitation

N\'eel spin-orbit torque allows a charge current pulse to efficiently manipulate the N\'eel vector in antiferromagnets, which offers a unique opportunity for ultrahigh density information storage with high speed. However, the reciprocal process of N\'eel spin-orbit torque, the generation of ultrafast charge current in antiferromagnets has not been demonstrated. Here, we report the experimental observation of charge current generation in antiferromagnetic metallic Mn2Au thin films using ultrafast optical excitation. The ultrafast laser pulse excites antiferromagnetic magnons, resulting in instantaneous non-equilibrium spin polarization at the antiferromagnetic spin sublattices with broken spatial symmetry. Then the charge current is generated directly via spin-orbit fields at the two sublattices, which is termed as the reciprocal phenomenon of N\'eel spin-orbit torque, and the associated THz emission can be detected at room temperature. Besides the fundamental significance on the Onsager reciprocity, the observed magnonic charge current generation in antiferromagnet would advance the development of antiferromagnetic THz emitter.Comment: 15 pages, 4 figures, this work was submitted to Nature Communications on Jan. 4th, 2023, now is under the 3rd review proces

Magnon-mediated interlayer coupling in an all-antiferromagnetic junction

The interlayer coupling mediated by fermions in ferromagnets brings about parallel and anti-parallel magnetization orientations of two magnetic layers, resulting in the giant magnetoresistance, which forms the foundation in spintronics and accelerates the development of information technology. However, the interlayer coupling mediated by another kind of quasi-particle, boson, is still lacking. Here we demonstrate such a static interlayer coupling at room temperature in an antiferromagnetic junction Fe2O3/Cr2O3/Fe2O3, where the two antiferromagnetic Fe2O3 layers are functional materials and the antiferromagnetic Cr2O3 layer serves as a spacer. The N\'eel vectors in the top and bottom Fe2O3 are strongly orthogonally coupled, which is bridged by a typical bosonic excitation (magnon) in the Cr2O3 spacer. Such an orthogonally coupling exceeds the category of traditional collinear interlayer coupling via fermions in ground state, reflecting the fluctuating nature of the magnons, as supported by our magnon quantum well model. Besides the fundamental significance on the quasi-particle-mediated interaction, the strong coupling in an antiferromagnetic magnon junction makes it a realistic candidate for practical antiferromagnetic spintronics and magnonics with ultrahigh-density integration.Comment: 19 pages, 4 figure

Absorption and fluorescence of dissolved organic matter in submarine hydrothermal vents off NE Taiwan

National Natural Science Foundation of China [40810069004]; Xiamen University [211-III]; National Science Council of Taiwan [NSC 98-2621-M-110-001-MY3]; "Aim for the Top" University Program of TaiwanThe role of hydrothermal vents as either a source or a sink for chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) in the oceans is unknown, since DOM absorption and fluorescence have not been reported for submarine hydrothermal vents. Water samples were collected from two shallow submarine hydrothermal vents off NE Taiwan, the white vent and the yellow vent, during two cruises in August, 2010. Absorption and excitation-emission-matrix fluorescence spectroscopy were used to characterize the optical properties of DOM from such extremely special environments. The absorption coefficients at wavelength 300 nm (a(300)) were much higher at the white vent mouth and 1 m below it (2.52 +/- 0.88 m(-1)) than in the background (0.34 +/- 0.12 m(-1)). This indicated that the white vent was a source of CDOM for seawater. Three fluorescent components were identified using parallel factor analysis: humic-like C1, tyrosine-like C3, and C2 as a combination of tryptophan-like and marine humic-like components. Both C1 and C3 (but not C2) had their highest fluorescence intensity at the white vent mouth and 1 m below it, suggesting the role of the vent as a source for both humic-like and tyrosine-like DOM. Samples from the yellow vent mouth also had a higher 0300 than the ambient seawater in our first cruise, but had fluorescence intensities of C(1-3) similar to the ambient seawater. Overall, the low humification index (HIX: 1.40 +/- 0.30) and the high autochthonous index (BIX: 1.27 +/- 0.63) indicated that the DOM likely had low humic contents and was mainly autochthonous of biological or bacterial origin in the study area. A biplot of HIX and BIX showed that DOM from the hydrothermal vents had a characteristic similar to terrestrial cave and spring waters, but was distinct from isolated humics. (C) 2011 Elsevier B.V. All rights reserved

Structural and Lipidomic Alterations of Striatal Myelin in 16p11.2 Deletion Mouse Model of Autism Spectrum Disorder

Myelin abnormalities have been observed in autism spectrum disorder (ASD). In this study, we seek to discover myelin-related changes in the striatum, a key brain region responsible for core ASD features, using the 16p11.2 deletion (16p11.2±) mouse model of ASD. We found downregulated expression of multiple myelin genes and decreased myelin thickness in the striatum of 16p11.2± mice versus wild type controls. Moreover, given that myelin is the main reservoir of brain lipids and that increasing evidence has linked dysregulation of lipid metabolism to ASD, we performed lipidomic analysis and discovered decreased levels of certain species of sphingomyelin, hexosyl ceramide and their common precursor, ceramide, in 16p11.2± striatum, all of which are major myelin components. We further identified lack of ceramide synthase 2 as the possible reason behind the decrease in these lipid species. Taken together, our data suggest a role for myelin and myelin lipids in ASD development

Using a Negative Binomial Regression Model for Early Warning at the Start of a Hand Foot Mouth Disease Epidemic in Dalian, Liaoning Province, China.

The hand foot and mouth disease (HFMD) is a human syndrome caused by intestinal viruses like that coxsackie A virus 16, enterovirus 71 and easily developed into outbreak in kindergarten and school. Scientifically and accurately early detection of the start time of HFMD epidemic is a key principle in planning of control measures and minimizing the impact of HFMD. The objective of this study was to establish a reliable early detection model for start timing of hand foot mouth disease epidemic in Dalian and to evaluate the performance of model by analyzing the sensitivity in detectability.The negative binomial regression model was used to estimate the weekly baseline case number of HFMD and identified the optimal alerting threshold between tested difference threshold values during the epidemic and non-epidemic year. Circular distribution method was used to calculate the gold standard of start timing of HFMD epidemic.From 2009 to 2014, a total of 62022 HFMD cases were reported (36879 males and 25143 females) in Dalian, Liaoning Province, China, including 15 fatal cases. The median age of the patients was 3 years. The incidence rate of epidemic year ranged from 137.54 per 100,000 population to 231.44 per 100,000population, the incidence rate of non-epidemic year was lower than 112 per 100,000 population. The negative binomial regression model with AIC value 147.28 was finally selected to construct the baseline level. The threshold value was 100 for the epidemic year and 50 for the non- epidemic year had the highest sensitivity(100%) both in retrospective and prospective early warning and the detection time-consuming was 2 weeks before the actual starting of HFMD epidemic.The negative binomial regression model could early warning the start of a HFMD epidemic with good sensitivity and appropriate detection time in Dalian

Simulation of Cooling Island Effect in Blue-Green Space Based on Multi-Scale Coupling Model

The mitigation of the urban heat island effect is increasingly imperative in light of climate change. Blue–green space, integrating water bodies and green spaces, has been demonstrated to be an effective strategy for reducing the urban heat island effect and enhancing the urban environment. However, there is a lack of coupled analysis on the cooling island effect of blue–green space at the meso-micro scale, with previous studies predominantly focusing on the heat island effect. This study coupled the single urban canopy model (UCM) with the mesoscale Weather Research and Forecasting (WRF) numerical model to simulate the cooling island effect of blue–green space in the Eastern Sea-River-Stream-Lake Linkage Zone (ESLZ) within the northern subtropical zone. In particular, we comparatively investigated the cooling island effect of micro-scale blue–green space via three mitigation strategies of increasing vegetation, water bodies, and coupling blue–green space, using the temperature data at the block scale within 100 m square of the urban center on the hottest day in summer. Results showed that the longitudinally distributed lakes and rivers in the city had a significant cooling effect on the ambient air temperature (Ta) at the mesoscale, with the largest cooling range occurring during the daytime and ranging from 1.01 to 2.15 °C. In contrast, a 5~20% increase in vegetation coverage or 5~15% increase in water coverage at the micro-scale was observed to reduce day and night Ta by 0.71 °C. Additionally, the most significant decrease in physiologically equivalent temperature (PET) was found in the mid-rise building environment, with a reduction of 2.65–3.26 °C between 11:00 and 13:00 h, and an average decrease of 1.25°C during the day. This study aims to guide the optimization of blue–green space planning at the meso-micro scale for the fast-development and expansion of new urban agglomerations

Electro-driving Permeation Performance of Nylon 6,6 Membrane

The study of separation properties of membrane under electro-driving condition is of an important guiding significance for the application of membrane in microdevices such as microfluidic chip. The electro-driving permeation performance of SO42- and Cl- of Nylon 6,6 membrane which was prepared by interfacial polymerization was investigated, and effects of electric field, operation time and temperature on the SO CL permeation performance of Nylon 6,6 membrane were studied. Experimental results showed that the permeation percentage of SO CL are high and similar for nylon 6,6 membrane. Ion permeation percentage was increased with electric field strength and operation time, but not changed with temperature. However, FITC labeled glycine and lysine were blocked totally, the molecular weight cutoff is around 500. So in a broader sense, the synthesized nylon 6,6 membrane is one kind of nanofiltration membrane and could be used to separate and concentrate big organic or biological molecules in miniaturized devices