Following the first experimental realization of graphene, other ultrathin materials with unprecedented electronic properties have been explored, with particular attention given to the heavy group-IV ...elements Si, Ge and Sn. Two-dimensional buckled Si-based silicene has been recently realized by molecular beam epitaxy growth, whereas Ge-based germanene was obtained by molecular beam epitaxy and mechanical exfoliation. However, the synthesis of Sn-based stanene has proved challenging so far. Here, we report the successful fabrication of 2D stanene by molecular beam epitaxy, confirmed by atomic and electronic characterization using scanning tunnelling microscopy and angle-resolved photoemission spectroscopy, in combination with first-principles calculations. The synthesis of stanene and its derivatives will stimulate further experimental investigation of their theoretically predicted properties, such as a 2D topological insulating behaviour with a very large bandgap, and the capability to support enhanced thermoelectric performance, topological superconductivity and the near-room-temperature quantum anomalous Hall effect.
The innate immune system is the first line of defense against pathogens, which is initiated by the recognition of pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated ...molecular patterns (DAMPs) by pattern recognition receptors (PRRs). Among all the PRRs identified, the toll-like receptors (TLRs) are the most ancient class, with the most extensive spectrum of pathogen recognition. Since the first discovery of Toll in
, numerous TLRs have been identified across a wide range of invertebrate and vertebrate species. It seems that TLRs, the signaling pathways that they initiate, or related adaptor proteins are essentially conserved in a wide variety of organisms, from Porifera to mammals. Molecular structure analysis indicates that most TLR homologs share similar domain patterns and that some vital participants of TLR signaling co-evolved with TLRs themselves. However, functional specification and emergence of new signaling pathways, as well as adaptors, did occur during evolution. In addition, ambiguities and gaps in knowledge still exist regarding the TLR network, especially in lower organisms. Hence, a systematic review from the comparative angle regarding this tremendous signaling system and the scenario of evolutionary pattern across Animalia is needed. In the current review, we present overview and possible evolutionary patterns of TLRs in non-mammals, hoping that this will provide clues for further investigations in this field.
Diseases are a significant impediment to aquaculture’s sustainable and healthy growth. The aquaculture industry is suffering significant financial losses as a result of the worsening water quality ...and increasing frequency of aquatic disease outbreaks caused by the expansion of aquaculture. Drug control, immunoprophylaxis, ecologically integrated control, etc. are the principal control strategies for fish infections. For a long time, the prevention and control of aquatic diseases have mainly relied on the use of various antibiotics and chemical drugs. However, long-term use of chemical inputs not only increases pathogenic bacteria resistance but also damages the fish and aquaculture environments, resulting in drug residues in aquatic products, severely impeding the development of the aquaculture industry. The development and use of aquatic vaccines are the safest and most effective ways to prevent aquatic animal diseases and preserve the health and sustainability of aquaculture. To give references for the development and implementation of aquatic vaccines, this study reviews the development history, types, inoculation techniques, mechanisms of action, development prospects, and challenges encountered with aquatic vaccines.
A pretest approach based on the complex Wishart distribution in polarimetric synthetic aperture radar (POLSAR) speckle filtering is proposed in this paper. The main principle is to select homogeneous ...pixels in a large-scale area in the filtering process, which is called pretesting. To preserve details and fine structures while despeckling, the homogeneous pixels are selected by comparing their 3 × 3 neighboring windows. A test statistic based on the complex Wishart distribution is used to decide the selection of homogeneous pixels. Speckle filtering is processed by summing up the homogeneous pixels with weights according to the values of their test statistics. To accelerate the pretest filter, we further propose a refined algorithm, which eliminates redundant operations without deteriorating the performance. We demonstrate the performance of the proposed algorithm by using both simulated and real airborne POLSAR data.
Vitamin D is suggested to have protective effects against type 1 diabetes. However, the results from observational studies have been inconsistent. We aimed to examine their association by conducting ...a meta-analysis of observational studies. Multiple databases were searched in June 2013 to identify relevant studies including both case-control and cohort studies. Either a fixed- or random-effects model was used to calculate the pooled risk estimate. We identified eight studies (two cohort studies and six case-control studies) on vitamin D intake during early life and three studies (two cohort studies and one case-control study) on maternal vitamin D intake during pregnancy. The pooled odds ratio for type 1 diabetes comparing vitamin D supplementation with non-supplementation during early life was 0.71 (95% confidence interval CI, 0.51-0.98). Similar results were observed in the case-control subgroup analysis but not in the cohort subgroup analysis. The pooled odds ratio with maternal intake of vitamin D during pregnancy was 0.95 (95% CI, 0.66-1.36). In conclusion, vitamin D intake during early life may be associated with a reduced risk of type 1 diabetes. However, there was not enough evidence for an association between maternal intake of vitamin D and risk of type 1 diabetes in the offspring.
Favorable growth of asymmetric hetero‐nanostructures consisting of plasmonic metals and semiconductors or topological nanomaterials is highly desired because the performance of nonlinear optical ...antennas is closely related to their composition and morphology symmetry. In this work, two methods are proposed to overgrow PtSe2, a semiconductor or topological semimetal material, onto Au nanorods (AuNRs) to form Au/AuPt/PtSe2 and Au/AgPtSe2 heterorods via wet chemical technique. Both Au/AuPt/PtSe2 and Au/AgPtSe2 heterorods show asymmetric morphologies: the Au/AuPt/PtSe2 heterorods show a partially hollow morphology with an etched AuNR coated by AuPt and PtSe2 shells; the Au/AgPtSe2 heterorods prepared by Ag‐mediated overgrowth method have a toothbrush shape with AgPtSe2 attached on the side surface near one end of AuNRs. The two asymmetric heterorods show significantly enhanced nonlinear radiations of second harmonic generation with the excitation laser wavelength tuning from 1220 to 1315 nm, and a maximal nonlinear enhancement factor of 16 is achieved, which is attributed to the interaction of gold core with platinum selenide shell and the broken symmetry of heterostructures. The findings provide a strategy to prepare metal‐topological heterostructures as optical antennas with optimized performance in the application of nonlinear photonic nanodevices.
Wet‐chemical method is applied to synthesize asymmetric heterorods through growing platinum selenide onto 1D Au nanorods. The asymmetric Au/AuPt/PtSe2 and Au/AgPtSe2 heterorods exhibit largely enhanced nonlinear emission of second harmonic generation, which is attributed to plasmonic interaction of gold core with platinum selenide shell and symmetry breaking of heterostructures.
Hourly rainfall measurements of 1919 national-level meteorological stations from 1981 through 2012 are used to document,for the first time,the climatology of extreme rainfall in hourly through 24-h ...accumulation periods in China. Rainfall amounts for 3-,6-,12- and 24-h periods at each station are constructed through running accumulation from hourly rainfall data that have been screened by proper quality control procedures. For each station and for each accumulation period,the historical maximum is found,and the corresponding 50-year return values are estimated using generalized extreme value theory. Based on the percentiles of the two types of extreme rainfall values among all the stations,standard thresholds separating Grade I,Grade II and Grade III extreme rainfall are established,which roughly correspond to the 70th and 90th percentiles for each of the accumulation periods. The spatial characteristics of the two types of extreme rainfall are then examined for different accumulation periods. The spatial distributions of extreme rainfall in hourly through 6-h periods are more similar than those of 12- and 24-h periods. Grade III rainfall is mostly found over South China,the western Sichuan Basin,along the southern and eastern coastlines,and in the large river basins and plains. There are similar numbers of stations with Grade III extreme hourly rainfall north and south of 30°N,but the percentage increases to about 70% south of 30°N as the accumulation period increases to 24 hours,reflecting richer moisture and more prolonged rain events in southern China. Potential applications of the extreme rainfall climatology and classification standards are suggested at the end.
Azoxystrobin (AZ) is one of the most widely used strobilurin fungicides in the world, and its residue has seriously endangered aquatic ecological security. Our previous data showed that AZ exposure ...may reduce the resistance of fish to rhabdovirus infection in aquatic environment. Here, we further reported a potential long-term adverse effect of AZ exposure on the antiviral and immunosuppressive recovery in fish, and observed that mitochondrial dynamic balance was disturbed by AZ in which excessive mitochondrial fission occurred in response to decreased ATP levels. When a recovery operation was performed in AZ-exposed cells and fish, infectivity of our model virus, spring viraemia of carp virus (SVCV), was significantly decreased in vitro (using the epithelioma papulosum cyprini EPC fish cell line) and in vivo (using zebrafish) in a time-dependent manner. Also, the expression of eight innate antiviral immune genes (IFNs, ISG15, MX1, RIG-I, IRF3, Nrf2 and HO-1) showed a similar change to SVCV replication between the longer exposure period and the expression recovery. Additionally, AZ facilitated horizontal transmission of SVCV in a static cohabitation challenge model, predicting the increase of the potential for the viral outbreak. Therefore, our data suggest that long-term effect of AZ on irreparable impairment in fish made AZ residue potentially greater for ecological risks.
•Azoxystrobin alters mitochondrial dynamics in fish.•Azoxystrobin induces an immune damage in fish.•Azoxystrobin decreases fish resistance to virus infection.•Azoxystrobin potentially improve the outbreak of fish viral diseases.
The rhizosphere microbiome facilitates a range of beneficial functions for its host plant. Thus, exploring the functionality of the rhizosphere microbiome and its underlying driving factors are ...fundamental for understanding how host plants benefit from their microbial symbionts. Herein, we utilized deep metagenomics sequencing to explore the rhizosphere microbiome in three rice (Oryza sativa L.) cultivars (hybrid rice and two japonica cultivars) that were planted in three spatially distant locations. Although rhizosphere prokaryotic communities were primarily affected by planting location, rice genotype signs were still detected. After the effect of planting location was ruled out, the top 24 genotype-discriminatory taxa were found to contribute 85.2% of the diagnostic accuracy for rice cultivars. The significant associations between the measured enzyme activities and the relative abundances of their coding genes validated that the recruitment of different rhizosphere microbes by hybrid rice and japonica cultivars further resulted in divergences in microbe-mediated functions. Compared with that in japonica, the rhizosphere in hybrid rice more efficiently mineralized N and P from organic matter, while mitigated N and K losses. The structural equation model depicted that the rice cultivars imposed direct (host-genotype-associated feature) and indirect (recruitment of specific rhizosphere microbiomes) effects on yield. Collectively, a conceptual model was constructed to infer the collective interplay among rice cultivars, rhizosphere microbiomes, and yield. Our findings provided novel insights into the molecular mechanism underlying the associations among rice cultivars, rhizosphere microbiomes, and yield.
•Rhizosphere microbiomes are primarily affected by geographic planting location, with detectable rice genotype signs.•Rice cultivar-discriminatory taxa contribute 85.2% of the diagnostic accuracy for cultivars.•Microbial enzyme activities are significantly associated with abundances of their coding genes.•Compared with japonica, Rhizosphere microbes in hybrid rice more efficiently mineralize N and P, while mitigate N and K losses than these in japonica.•Conceptual model infers the interplay between rice cultivar, rhizosphere microbiome and yield.
Ship Detection Using Polarization Cross-Entropy Jiong Chen, Jiong Chen; Yilun Chen, Yilun Chen; Jian Yang, Jian Yang
IEEE geoscience and remote sensing letters,
10/2009, Volume:
6, Issue:
4
Journal Article
Peer reviewed
In this letter, polarization cross-entropy is introduced based on the eigendecomposition of the polarimetric coherence matrix. Then, the new parameter is employed for ship detection. From ...experimental results, it is derived that the distribution of the polarization cross-entropy in ocean regions can be well approximated by a generalized exponential distribution. Then, a constant-false-alarm-rate ship-detection method is proposed based on the distribution of the polarization cross-entropy. Using experimental results, the authors demonstrate the effectiveness of the new method in ship detection.
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