Visual Perception Generalization for Vision-and-Language Navigation via Meta-Learning.

Vision-and-language navigation (VLN) is a challenging task that requires an agent to navigate in real-world environments by understanding natural language instructions and visual information received in real time. Prior works have implemented VLN tasks on continuous environments or physical robots, all of which use a fixed-camera configuration due to the limitations of datasets, such as 1.5-m height, 90° horizontal field of view (HFOV), and so on. However, real-life robots with different purposes have multiple camera configurations, and the huge gap in visual information makes it difficult to directly transfer the learned navigation skills between various robots. In this brief, we propose a visual perception generalization strategy based on meta-learning, which enables the agent to fast adapt to a new camera configuration. In the training phase, we first locate the generalization problem to the visual perception module and then compare two meta-learning algorithms for better generalization in seen and unseen environments. One of them uses the model-agnostic meta-learning (MAML) algorithm that requires few-shot adaptation, and the other refers to a metric-based meta-learning method with a feature-wise affine transformation (AT) layer. The experimental results on the VLN-CE dataset demonstrate that our strategy successfully adapts the learned navigation skills to new camera configurations, and the two algorithms show their advantages in seen and unseen environments respectively.

Ligustrazine exerts neuroprotective effects via circ_0008146/miR-709/Cx3cr1 axis to inhibit cell apoptosis and inflammation after cerebral ischemia/reperfusion injury.

BACKGROUND: Ligustrazine is a traditional Chinese herbal medicine that has long been used to treat cerebral ischemic disorders. However, the molecular mechanisms of ligustrazine in cerebral ischemia/reperfusion (I/R) damage have not been clear elucidated. The aim of this study was to examine the neuroprotective mechanisms of ligustrazine in cerebral I/R. METHODS: 9 C57BL/6 mice were randomly divided to three groups: Sham group (n = 3), Middle cerebral artery occlusion (MCAO) group (n = 3), and MCAO + Ligustrazine group (n = 3). The neurological deficit score was evaluated, the cerebral infarct volume was measured by triphenylterazolium chloride (TTC) staining. Differentially expressed (DE) messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) were analyzed using the R package DEseq2 based on P-value < 0.05 and Log2 |fold change (FC)| ≥ 2 in sham group vs MCAO group and MCAO group vs ligustrazine group by high-throughput sequencing. Function enrichment analysis, the protein-protein interaction (PPI) of neurogenesis related genes were performed. The neurogenesis related competitive endogenous RNA (ceRNA) network was constructed. RESULTS: The expression of circ_0008146 was considerably higher in the MCAO group than the Sham group, and ligustrazine treatment markedly decreased the expression of circ_0008146 in MCAO. Next, the circ_0008146 ceRNA network was established, including circ_0008146-miR-709-Cx3cr1 ceRNA network. Besides, real time quantitative polymerase chain reaction (RT-qPCR) assay identified that miR-709 expression was considerably lower and Cx3cr1 expression was higher in the MCAO group than Sham group, and ligustrazine treatment markedly increased the miR-709 expression and reduced Cx3cr1 expression in MCAO. Further, silencing of circ_0008146 inhibited the concentration of Interleukin 6 (IL-6), Tumor Necrosis Factor alpha (TNF-α) and reduced neuron cell death and up-regulated miR-709 expression and down-regulated Cx3cr1 expression in Lipopolysaccharide (LPS) induced BV-2 cells. Dual-Luciferase reporter gene assay verified that circ_0008146 targeted miR-709. CONCLUSION: Ligustrazine targets circ_0008146/miR-709/Cx3cr1 axis to inhibit cell apoptosis and inflammation after cerebral ischemia/reperfusion injury.

Effects of Silicon Dioxide/Graphene Oxide Hybrid Modification on Curing Kinetics of Epoxy Resin.

In this study, SiO2-grafted graphene oxide (GO-SiO2) was prepared using the oxygen-containing group on the GO surface as the active site of the reaction. The chemical structure, morphology, and particle size of GO and GO-SiO2 were carefully investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetry, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy, and the results proved that the grafting modification was successful. Furthermore, epoxy (EP)/GO composites were prepared, and the effects of unmodified GO and GO-SiO2 on the curing kinetics of EP were comparatively studied by differential scanning calorimetry (DSC). The results showed that, compared with neat EP and EP/GO, GO-SiO2 significantly reduces the curing temperature of the composites, indicating that GO-SiO2 has a more significant catalytic effect on the curing process of EP. The calculation results of the Kissinger method showed that the curing activation energy of EP/GO-SiO2 is obviously lower than that of EP/GO and neat EP. Results of the Ozawa method showed that the introduction of GO-SiO2 reduces the curing activation energy during the whole curing process, and in the middle and late stages of curing (α = 0.5-1) can significantly reduce the curing activation energy. The related mechanism has been proposed.

The construction of neurogenesis-related ceRNA network of ischemic stroke treated by oxymatrine.

BACKGROUND: Known as a disease associated with high mortality, disability and a significant financial burden, ischemic stroke ranks as one of the three diseases threatening human health. Recent advances in omics technology created opportunities to uncover the mechanism in ischemic stroke occurrence and treatment. In this study, we aimed to construct the competitive endogenous RNA (ceRNA) networks of ischemic stroke treated by oxymatrine intervention. METHOD: The middle cerebral artery occlusion (MCAO) mouse model of ischemic stroke was constructed, and oxymatrine was administered. Then RNA-Sequencing was performed and integrated analysis of mRNAs, lncRNAs and circRNAs was conducted to reveal the pharmacology of oxymatrine. Functional enrichment analysis was performed to explore the underlying mechanism of differentially expressed (DE) mRNAs. The protein-protein interaction (PPI) network of neurogenesis-related genes and long noncoding RNAs (lncRNAs)/circular RNAs (circRNAs) based ceRNA networks were constructed. RESULTS: First, this study revealed the DE-mRNAs, DE-lncRNAs and DE-circRNAs between Oxymatrine treated group and the MCAO group. Then, the common 1231 DE-mRNAs, 32 DE-lncRNAs and 31 DE-circRNAs with opposite trends were identified. The Kyoto Encyclopedia of Genes and Genomes to identify the functional enrichment of 1231 DE-mRNAs were enriched in neurogenesis-related biological processes. Based on neurogenesis-related DE-mRNAs, the PPI network was constructed, and hub genes were identified based on centrality. Finally, both the lncRNA-based and circRNAs-based ceRNA networks were constructed. CONCLUSION: In summary, this study identified novel coding and noncoding ischemic stroke targets of oxymatrine-treated MCAO. Most importantly, we identified lncRNAs and circRNAs candidates as potential oxymatrine targets and constructed the neurogenesis-related ceRNA networks.

Evaluation of Blend Uniformity and Terminal Point during Continuous Mixing in Water for Modified Double-Base Propellant Components Using a Near-Infrared Method.

A near-infrared (NIR) spectrometer was used to test the double-base absorbent powder sample and to quantitatively analyze the contents of each component as well as their dispersion uniformity to establish a rapid quantitative test method for blending uniformity of modified double-base (MDB) propellant components. First, the quantitative calibration models of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were constructed based on sample testing, and the RDX model's correlation coefficient was 0.9929. Then, during the blending process, NIR spectra were continually collected. For the original spectra of samples, the blend uniformity was assessed using the coefficient of moving block standard deviation (MBSD). After 160 min, the sample's MBSD value had reached a steady state of less than 0.003, indicating that the sample's components were distributed uniformly. The findings reveal that NIR spectroscopy can be used to verify the blending uniformity of MDB propellant components.

Integrated Analysis of Competitive Endogenous RNA Networks in Acute Ischemic Stroke.

Background: Acute ischemic stroke (AIS) is a severe neurological disease with complex pathophysiology, resulting in the disability and death. The goal of this study is to explore the underlying molecular mechanisms of AIS and search for new potential biomarkers and therapeutic targets. Methods: Integrative analysis of mRNA and miRNA profiles downloaded from Gene Expression Omnibus (GEO) was performed. We explored differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMirs) after AIS. Target mRNAs of DEMirs and target miRNAs of DEGs were predicted with target prediction tools, and the intersections between DEGs and target genes were determined. Subsequently, Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses, Gene set enrichment analysis (GSEA), Gene set variation analysis (GSVA), competitive endogenous RNA (ceRNA) (lncRNA-miRNA-mRNA) network, protein-protein interaction (PPI) network, and gene transcription factors (TFs) network analyses were performed to identify hub genes and associated pathways. Furthermore, we obtained AIS samples with evaluation of immune cell infiltration and used CIBERSORT to determine the relationship between the expression of hub genes and infiltrating immune cells. Finally, we used the Genomics of Drug Sensitivity in Cancer (GDSC) database to predict the effect of the identified targets on drug sensitivity. Result: We identified 293 DEGs and 26 DEMirs associated with AIS. DEGs were found to be mainly enriched in inflammation and immune-related signaling pathways through enrichment analysis. The ceRNA network included nine lncRNAs, 13 miRNAs, and 21 mRNAs. We used the criterion AUC >0.8, to screen a 3-gene signature (FBL, RPS3, and RPS15) and the aberrantly expressed miRNAs (hsa-miR-125a-5p, hsa-miR-125b-5p, hsa-miR-148b-3p, and hsa-miR-143-3p) in AIS, which were verified by a method of quantitative PCR (qPCR) in HT22 cells. T cells CD8, B cells naïve, and activated NK cells had statistical increased in number compared with the acute cerebral infarction group. By predicting the IC50 of the patient to the drug, AZD0530, Z.LLNle.CHO and NSC-87877 with significant differences between the groups were screened out. AIS demonstrated heterogeneity in immune infiltrates that correlated with the occurrence and development of diseases. Conclusion: These findings may contribute to a better understanding of the molecular mechanisms of AIS and provide the basis for the development of novel treatment targets in AIS.

Circulating miRNA-3552 as a Potential Biomarker for Ischemic Stroke in Rats.

OBJECTIVE: With the growing incidence of ischemic stroke worldwide, there is an urgent need to identify blood biomarkers for ischemic stroke patients. Thus, our aim was to identify potential circulating microRNA (miRNA) as a potential biomarker and to explore its potential mechanism for ischemic stroke in rats. METHODS: The mRNA dataset GSE97537 and miRNA dataset GSE97532 were downloaded from the Gene Expression Omnibus (GEO) GSE97537 including 7 middle cerebral artery occlusion (MCAO) rat brain tissues and 5 sham-operated rat brain tissues GSE97532 including 6 MCAO rat blood samples and 3 sham-operated rat blood samples. Differentially expressed mRNAs and miRNAs with corrected p value ≤ 0.01 and fold change ≥2 or ≤0.05 were identified. To explore potential biological processes and pathways of differentially expressed mRNAs, functional enrichment analysis was performed. The target mRNAs of differentially expressed miRNAs were predicted using DNA Intelligent Analysis (DIANA)-microT tools. The target mRNAs and differentially expressed mRNAs were intersected. RESULTS: 1228 differentially expressed mRNAs in MCAO rat brain tissues were identified. Highly expressed mRNAs were mainly enriched in the inflammatory responses. Nine differentially expressed miRNAs were identified in MCAO rat blood samples. A total of 673 target mRNAs were predicted to significantly bind these differentially expressed miRNAs. Among them, 54 target mRNAs were differentially expressed in MCAO rat blood samples. Enrichment analysis results showed that these 54 target mRNAs were closely related to neurological diseases and immune responses. Among all miRNA-mRNA relationship, miR-3552-CASP3 interaction was identified, indicating that CASP3 might be mediated by miR-3552. Functional enrichment analysis revealed that CASP3 was involved in the apoptosis pathway, indicating that miR-3552 might participate in apoptosis by CASP3. CONCLUSION: Our findings reveal that circulating miR-3552 shows promise as a potential biomarker for ischemic stroke in rats.

Impact of Nb(V) Substitution on the Structure and Optical and Photoelectrochemical Properties of the Cu5(Ta1- xNb x)11O30 Solid Solution.

A family of solid solutions, Cu5(Ta1- xNb x)11O30 (0 ≤ x ≤ 0.4), was investigated as p-type semiconductors for their band gaps and energies and for their activity for the reduction of water to molecular hydrogen. Compositions from 0 to 40 mol % niobium were prepared in high purity by solid-state methods, accompanied by only very small increases in the lattice parameters of ∼0.05% and with the niobium and tantalum cations disordered over the same atomic sites. However, an increasing niobium content causes a significant decrease in the bandgap size from ∼2.58 to ∼2.05 eV owing to the decreasing conduction band energies. Linear-sweep voltammetry showed an increase in cathodic photocurrents with niobium content and applied negative potential of up to -0.6 mA/cm2 (pH ∼7.3; AM 1.5 G light filter with an irradiation intensity of ∼100 mW/cm2). The cathodic photocurrents could be partially stabilized by heating the polycrystalline films in air at 550 °C for 1 h to produce surface nanoislands of CuO or using protecting layers of aluminum-doped zinc oxide and titania. Aqueous suspensions of the Cu5(Ta1- xNb x)11O30 powders were also found to be active for hydrogen production under visible-light irradiation in a 20% aqueous methanol solution with the highest apparent quantum yields for the 10% and 20% Nb-substituted samples. Electronic structure calculations show that the increased photocurrents and hydroen evolution activities of the solid solutions arise near the percolation threshold of the niobate/tantalate framework wherein the Nb cations establish an extended -O-Nb-O-Nb-O- diffusion pathway for the minority carriers. The latter also reveals a novel pathway for enhancing charge separation as a function of the niobium-oxide connectivity. Thus, these results illustrate the advantages of using solid solutions to achieve the smaller bandgap sizes and band energies that are needed for solar-driven photocatalytic reactions.

Theoretical study on crystal morphologies of 1,1-diamino-2,2-dinitroethene in solvents: Modified attachment energy model and occupancy model.

In this study, the growth morphologies of 1,1-diamino-2,2-dinitroethene (FOX-7) in vacuum and solvent conditions were investigated by molecular dynamics simulation. The modified attachment energy (MAE) model and occupancy model were used separately to predict the crystal morphology by calculating relative growth rate of different crystal faces in H2O/NMP and DMSO/AC solvent system. The calculated results show that the (0 1 1) face and (1 0 1) face are the most important crystal face in both two solvents towards the MAE model and the occupancy model, respectively. Compared with that from the MAE model, the predicted morphologies from the occupancy model are in better agreement with the experimental results. Radial distribution function (RDF) analyses were employed to demonstrate that the hydrogen bonds and vdW interactions play the dominant role between solvent molecules and FOX-7 surfaces. The above results allow us to understand the role played by solvents and solute molecules on growth morphologies of FOX-7 crystals.

Wavelength dependent photochemical charge transfer at the Cu2O-BiVO4 particle interface - evidence for tandem excitation.

The understanding of the photochemical charge transfer properties of powdered semiconductors is of relevance to artificial photosynthesis and the production of solar fuels. Here we use surface photovoltage spectroscopy to probe photoelectrochemical charge transfer between bismuth vanadate (BiVO4) and cuprous oxide (Cu2O) particles as a function of wavelength and film thickness. Optimized conditions produce a -2.10 V photovoltage under 2.5 eV (0.1 mW cm-2) illumination, which suggests the possibility of a water splitting system based on a BiVO4-Cu2O direct contact particle tandem.

Magnetometer and Gyroscope Calibration Method with Level Rotation.

Micro electro mechanical system (MEMS) gyroscopes and magnetometers are usually integrated into a sensor module or chip and widely used in a variety of applications. In existing integrated gyroscope and magnetometer calibration methods, rotation in all possible orientations is a necessary condition for a good calibration result. However, rotation around two or more axes is difficult to attain, as it is limited by the range of movement of vehicles such as cars, ships, or planes. To solve this problem, this paper proposes an integrated magnetometer and gyroscope calibration method with level rotation. The proposed method presents a redefined magnetometer output model using level attitude. New gyroscope and magnetometer calibration models are then deduced. In addition, a simplified cubature Kalman filter (CKF) is established to estimate calibration parameters. This method possesses important value for application in actual systems, as it only needs level rotation for real-time calibration of gyroscopes and magnetometers. Theoretical analysis and test results verify the validity and feasibility of this method.

Surface Photovoltage Measurements on a Particle Tandem Photocatalyst for Overall Water Splitting.

Surface photovoltage spectroscopy (SPS) is used to measure the photopotential across a Ru-SrTiO3:Rh/BiVO4 particle tandem overall water splitting photocatalyst. The tandem is synthesized from Ru-modified SrTiO3:Rh nanocrystals and BiVO4 microcrystals by electrostatic assembly followed by thermal annealing. It splits water into H2 and O2 with an apparent quantum efficiency of 1.29% at 435 nm and a solar to hydrogen conversion efficiency of 0.028%. According to SPS, a photovoltage develops above 2.20 eV, the effective band gap of the tandem, and reaches its maximal value of -2.45 V at 435 nm (2.44 mW cm-2), which corresponds to 96% of the theoretical limit of the photocatalyst film on the fluorine-doped tin-oxide-coated glass (FTO) substrate. Charge separation is 82% reversible with 18% of charge carriers being trapped in defect states. The unusually strong light intensity dependence of the photovoltage (1.16 V per decade) is attributed to depletion layer changes inside of the BiVO4 microcrystals. These findings promote the understanding of solar energy conversion with inorganic particle photocatalysts.

Interactions between poly-(phthalazinone ether sulfone ketone) (PPESK) and TNT or TATB in polymer bonded explosives: a molecular dynamic simulation study.

The glass transition temperature (T g) and density of poly-(phthalazinone ether sulfone ketone) (PPESK A) were estimated by molecular dynamic (MD) simulation. A novel poly-(phthalazinone ether sulfone ketone) (PPESK B) was constructed by introducing nitrol and amini energetic groups into PPESK A, and T g and density were also simulated for PPESK B. The estimated T g values of PPESK A were very close to experimental results, while for PPESK B three estimated values differed by < 5 K. The interactions between explosives and polymer binders of polymer bonded explosives (PBXs) were simulated by MD. Comparison of the cohesive energy densities (CED) and solubility parameter (δ) values of PBXs, polymer binders, and mono-explosives indicate that, upon introducing polymer binders, the CED and δ values of PBXs decreased compared with those of corresponding mono-explosives. The binding energies (E bind) imply that 2,4,6-trinitrotoluene-based PBXs are more stable than 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based PBXs. The mechanical properties, Young's modulus E, shear modulus G, bulk modulus K, Poisson's ratio γ and Cauchy pressure (C 12 -C 44) of the PBXs were assessed. The rigidity of the PBXs was found to be lower than that of mono-explosives. All K/G values were positive, indicating that PBXs are flexible. Based on these mechanical properties results, PBXs using PPESK B as a binder are superior to those using PPESK A as a binder. Due to the low C 12 -C 44 values of the PBXs, the ductility of the materials of the fracture surface is poorer, especially for TATB-based PBXs.