Advances on the investigation of landslides by space-borne synthetic aperture radar interferometry

Landslides are destructive geohazards to people and infrastructure, resulting in hundreds of deaths and billions of dollars of damage every year. Therefore, mapping the rate of deformation of such geohazards and understanding their mechanics is of paramount importance to mitigate the resulting impacts and properly manage the associated risks. In this paper, the main outcomes relevant to the joint European Space Agency (ESA) and the Chinese Ministry of Science and Technology (MOST) Dragon-5 initiative cooperation project ID 59,339 “Earth observation for seismic hazard assessment and landslide early warning system” are reported. The primary goals of the project are to further develop advanced SAR/InSAR and optical techniques to investigate seismic hazards and risks, detect potential landslides in wide regions, and demonstrate EO-based landslide early warning system over selected landslides. This work only focuses on the landslide hazard content of the project, and thus, in order to achieve these objectives, the following tasks were developed up to now: a) a procedure for phase unwrapping errors and tropospheric delay correction; b) an improvement of a cross-platform SAR offset tracking method for the retrieval of long-term ground displacements; c) the application of polarimetric SAR interferometry (PolInSAR) to increase the number and quality of monitoring points in landslide-prone areas; d) the semiautomatic mapping and preliminary classification of active displacement areas on wide regions; e) the modeling and identification of landslides in order to identify triggering factors or predict future displacements; and f) the application of an InSAR-based landslide early warning system on a selected site. The achieved results, which mainly focus on specific sensitive regions, provide essential assets for planning present and future scientific activities devoted to identifying, mapping, characterizing, monitoring and predicting landslides, as well as for the implementation of early warning systems.This work was supported by the ESA-MOST China DRAGON-5 project with ref. 59339, by the Spanish Ministry of Science and Innovation, the State Agency of Research (AEI), and the European Funds for Regional Development under grant [grant number PID2020-117303GB-C22], by the Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital in the framework of the project CIAICO/2021/335, by the Natural Science Foundation of China [grant numbers 41874005 and 41929001], the Fundamental Research Funds for the Central University [grant numbers 300102269712 and 300102269303], and China Geological Survey Project [grant numbers DD20190637 and DD20190647]. Xiaojie Liu and Liuru Hu have been funded by Chinese Scholarship Council Grants Ref. [grant number 202006560031] and [grant number 202004180062], respectively

Analysis of the genetic architecture of maize kernel size traits by combined linkage and association mapping

Kernel size‐related traits are the most direct traits correlating with grain yield. The genetic basis of three kernel traits of maize, kernel length (KL), kernel width (KW) and kernel thickness (KT), was investigated in an association panel and a biparental population. A total of 21 single nucleotide polymorphisms (SNPs) were detected to be most significantly (P \u3c 2.25 × 10−6) associated with these three traits in the association panel under four environments. Furthermore, 50 quantitative trait loci (QTL) controlling these traits were detected in seven environments in the intermated B73 × Mo17 (IBM) Syn10 doubled haploid (DH) population, of which eight were repetitively identified in at least three environments. Combining the two mapping populations revealed that 56 SNPs (P \u3c 1 × 10−3) fell within 18 of the QTL confidence intervals. According to the top significant SNPs, stable‐effect SNPs and the co‐localized SNPs by association analysis and linkage mapping, a total of 73 candidate genes were identified, regulating seed development. Additionally, seven miRNAs were found to situate within the linkage disequilibrium (LD) regions of the co‐localized SNPs, of which zma‐miR164e was demonstrated to cleave the mRNAs of Arabidopsis CUC1, CUC2 and NAC6 in vitro. Overexpression of zma‐miR164e resulted in the down‐regulation of these genes above and the failure of seed formation in Arabidopsis pods, with the increased branch number. These findings provide insights into the mechanism of seed development and the improvement of molecular marker‐assisted selection (MAS) for high‐yield breeding in maize

Effective and fast-screening route to evaluate dynamic elastomer-filler network reversibility for sustainable rubber composite design

.The introduction of self-healing and reprocessability into conventional vulcanized rubbers has been recognized as a promising strategy to promote elastomer circularity. However, the reversibility and recovery of cross-linking polymer networks have often been assessed by static mechanical testing, which highly limits the understanding of the underlying microscale mechanisms. In this work, we investigated the network recovery of natural rubber (NR)/carbon black (CB) nanocomposites using Fourier transform (FT) rheology coupled with large amplitude oscillation shear (LAOS) technology across linear and nonlinear regimes (0.01–500%). The self-healing process of the rubber composite networks was monitored by using a programmed time–temperature oscillation shear measurement. The role of CB particle size in the filler network recovery was also discussed from the perspective of strain-induced crystallization of NR. Coupling FT-rheology and LAOS analysis, two distinct nonlinear enhancement behaviors beyond the linear viscoelastic regime were detected in the rubber nanocomposites, which were ascribed to the filler network disruption followed by the polymer network deformation. The relationship of the nonlinearity parameter I3/1 as a function of strain amplitude was selected to quantify the nonlinear rheological responses, where the role of the filler and polymer on the network recovery can therefore be differentiated. This work provides an efficient method to evaluate the self-healing and reprocessability of cross-linked rubbers and offers a fast-screen route for formulation development and sustainable rubber composite design

Tuning triboelectric and energy harvesting properties of dielectric elastomers <i>via</i> dynamic ionic crosslinks

The bromination of poly(isobutylene-co-isoprene) rubber introduces a small amount of bromide groups (1–2 mol%) to the elastomer backbone and creates new opportunities for functionalisation, as compared to other saturated and diene elastomers. In this work, three types of nucleophile reagents: namely pyridine, triphenylphosphine and imidazoles bearing four types of side groups of methyl, ethyl, hydroxyl or vinyl group were introduced to brominated poly(isobutylene-co-isoprene) rubber (BIIR) through nucleophile substitution with the bromine via solid-state rubber compounding and curing processes. The resulted ionic aggregates act as physical crosslinks and their size and density directly affected the mechanical reinforcement, self-healing and dynamic mechanical properties of the elastomers. The smaller and polar imidazolyl/bromine pairs led to the highest reinforcement beyond even the sulfur-cured BIIR counterparts. The 1-ethyl imidazole (EIm) modified BIIR showed the highest tensile strength of 17.01 ± 1.89 MPa and elongation at break of 1402 ± 69% with self-healing efficiency of 63.7%, after being treated at 140 °C for 30 min. In addition, the inclusion of the ionic clusters enhanced the relative permittivity of the elastomer, thereby enhancing the energy conversion efficiencies. The nucleophile substitution reaction via conventional solid-state rubber compounding processes provides a facile crosslinking and reinforcement strategy for halogen-containing polymers. In addition, the dynamic ionic crosslinking networks spontaneously benefit electromechanical and self-healing properties of the dielectric elastomers

Vitamin B1 Helps to Limit Mycobacterium tuberculosis Growth via Regulating Innate Immunity in a Peroxisome Proliferator-Activated Receptor-γ-Dependent Manner

It is known that vitamin B1 (VB1) has a protective effect against oxidative retinal damage induced by anti-tuberculosis drugs. However, it remains unclear whether VB1 regulates immune responses during Mycobacterium tuberculosis (MTB) infection. We report here that VB1 promotes the protective immune response to limit the survival of MTB within macrophages and in vivo through regulation of peroxisome proliferator-activated receptor γ (PPAR-γ). VB1 promotes macrophage polarization into classically activated phenotypes with strong microbicidal activity and enhanced tumor necrosis factor-α and interleukin-6 expression at least in part by promoting nuclear factor-κB signaling. In addition, VB1 increases mitochondrial respiration and lipid metabolism and PPAR-γ integrates the metabolic and inflammatory signals regulated by VB1. Using both PPAR-γ agonists and deficient mice, we demonstrate that VB1 enhances anti-MTB activities in macrophages and in vivo by down-regulating PPAR-γ activity. Our data demonstrate important functions of VB1 in regulating innate immune responses against MTB and reveal novel mechanisms by which VB1 exerts its function in macrophages

Effective and Fast-Screening Route to Evaluate Dynamic Elastomer-Filler Network Reversibility for Sustainable Rubber Composite Design

The introduction of self-healing and reprocessability into conventional vulcanized rubbers has been recognized as a promising strategy to promote elastomer circularity. However, the reversibility and recovery of cross-linking polymer networks have often been assessed by static mechanical testing, which highly limits the understanding of the underlying microscale mechanisms. In this work, we investigated the network recovery of natural rubber (NR)/carbon black (CB) nanocomposites using Fourier transform (FT) rheology coupled with large amplitude oscillation shear (LAOS) technology across linear and nonlinear regimes (0.01–500%). The self-healing process of the rubber composite networks was monitored by using a programmed time–temperature oscillation shear measurement. The role of CB particle size in the filler network recovery was also discussed from the perspective of strain-induced crystallization of NR. Coupling FT-rheology and LAOS analysis, two distinct nonlinear enhancement behaviors beyond the linear viscoelastic regime were detected in the rubber nanocomposites, which were ascribed to the filler network disruption followed by the polymer network deformation. The relationship of the nonlinearity parameter I3/1 as a function of strain amplitude was selected to quantify the nonlinear rheological responses, where the role of the filler and polymer on the network recovery can therefore be differentiated. This work provides an efficient method to evaluate the self-healing and reprocessability of cross-linked rubbers and offers a fast-screen route for formulation development and sustainable rubber composite design

Response of microbial communities in the tobacco phyllosphere under the stress of validamycin

Validamycin, is classified as an environmentally friendly fungicide. It has high efficacy with little associated pollution risk, and it has been used in China on tobacco for many years especially during leaf spot season. To understand changes in microbial communities and functional aspects of the tobacco phyllosphere after exposure to validamycin, the chemical was sprayed on tobacco leaves during brown spot epidemic periods caused by Alternaria alternata, and asymptomatic and symptomatic leaves of tobacco were sampled at different times (0 day before, 5, 10, and 15 days after application). The fungal and bacterial population diversity and structure were revealed using Illumina NovaSeq PE250 high-throughput sequencing technology, and Biolog-ECO technology which analyzes the metabolic differences between samples by using different carbon sources as the sole energy source. The results showed that the microbial community structure of both asymptomatic and symptomatic tobacco leaves changed after the application of valproate, with the microbial community structure of the asymptomatic tobacco leaves being more strongly affected than that of the symptomatic leaves, and the diversity of bacteria being greater than that of fungi. Phyllosphere fungal diversity in asymptomatic leaves increased significantly after application, and bacterial abundance and diversity in both asymptomatic and symptomatic leaves first increased and then decreased. Validamycin treatment effectively reduced the relative abundance of Alternaria, Cladosporium, Kosakonia, and Sphingomonas in leaves showing symptoms of tobacco brown spot, while the relative abundance of Thanatephorus, Pseudomonas, and Massilia increased significantly after application. Furthermore, the ability to metabolize a variety of carbon sources was significantly reduced in both types of leaves after validamycin application, and both types had a weaker ability to metabolize α-Ketobutyric Acid after application. This study reveals phyllosphere micro-ecological changes in symptomatic and asymptomatic tobacco leaves during different periods after validamycin application and the effects on the metabolic capacity of phyllosphere microorganisms. It can provide some basis for exploring the effect of validamycin on the control of tobacco brown spot

Mid-infrared materials and devices on a Si platform for optical sensing

In this article, we review our recent work on mid-infrared (mid-IR) photonic materials and devices fabricated on silicon for on-chip sensing applications. Pedestal waveguides based on silicon are demonstrated as broadband mid-IR sensors. Our low-loss mid-IR directional couplers demonstrated in SiNx waveguides are useful in differential sensing applications. Photonic crystal cavities and microdisk resonators based on chalcogenide glasses for high sensitivity are also demonstrated as effective mid-IR sensors. Polymer-based functionalization layers, to enhance the sensitivity and selectivity of our sensor devices, are also presented. We discuss the design of mid-IR chalcogenide waveguides integrated with polycrystalline PbTe detectors on a monolithic silicon platform for optical sensing, wherein the use of a low-index spacer layer enables the evanescent coupling of mid-IR light from the waveguides to the detector. Finally, we show the successful fabrication processing of our first prototype mid-IR waveguide-integrated detectors