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Oceanic air samples (gas + particle phases) were collected over the Shanghai-Arctic background oceanic region during the Chinese Arctic Research expedition 2021. Full scan mode (semi-quantitative) and selective ion monitoring mode (quantitative) were used to analyze separately 72 polycyclic aromatic compounds (PACs) & C 11 –C 35 n-Alkanes (n-Alks) and unresolved complex mixtures (UCMs, including aromatic-like and aliphatic-like compounds) in these samples. The concentration of ΣPACs in the gas-phase and particle-phase were 0.40–8.5 ng m−3 (2.4 ± 1.7 ng m−3) and 0.059–1.1 ng m−3 (0.21 ± 0.23 ng m−3), respectively. While Σn-Alks in the gas-phase and particle-phase were 2.2–80 ng m−3 (mean = 18 ± 24 ng m−3) and 2.2–20 ng m−3 (mean = 8.6 ± 5.0 ng m−3), respectively. The semi-quantitative result indicated that aromatic-like UCMs were 14–1400 times higher than those of ΣPACs in these two phases, while aliphatic-like UCMs were 1.2–25 times higher than those of Σn-Alks. Through three-dimensional identification of the one-dimensional GC-MS chromatogram (with the x-axis representing GC retention time, the y-axis representing m/z, and the z-axis representing peak intensity), we found that aromatic-like UCMs were primarily composed of phenanthrene & anthracene similar PACs, while aliphatic-like UCMs were predominated by long-chain alkanes. The source identification shows that oil-gas leakage was the dominant source of PACs, followed by petroleum & coal combustion and biomass combustion; n-Alks might be mainly originated from anthropogenic sources, while nature sources at high latitudes cannot be ignored as well. Aromatic-like UCMs had a decreasing latitude trend and the presence of 5–6 ring aromatic-like UCMs enclosed within organic aerosols could pose a significant ecological risk, particularly in high latitude regions. Net uptake of atmospheric carbon caused by dry deposition of aromatic-like & aliphatic-like UCMs varied significantly geographically with mid- and low-latitude seas. The non-polar and weakly polar substances were not the major components of organic carbon in oceanic air of high latitude areas. [Display omitted] • Identification of aromatic-like UCMs were Phe & Ant similar PACs. • Identification of aliphatic-like UCMs were long-chain Alkanes. • Occurrence of aromatic-like UCM had decreasing latitude trend, aliphatic-like UCM shown no trend. • Net uptake of atmospheric carbon caused by dry deposition of UCMs. [ABSTRACT FROM AUTHOR]

• The overall transmission error (OTE) is directly applied to the planet fault differential diagnosis (DD) for the tooth flank spall and the gear fillet crack. • A novel reordered SVD approach guided by the sparse index L2/L1 norm is proposed for fault-dependent residual OTE extraction. • Fault components with different scales can be accurately extracted in residual OTE. • The proposed DD framework is robust in extremely low-speed or varying-speed conditions. Owing to recent studies on the relationship between the transmission error and the localized gear fault, TE-based differential diagnosis (DD) technology has emerged as a promising approach to identifying the tooth flank spall and the gear fillet crack which have similar signatures but quite different fault mechanisms and prognoses. However, due to complex structural factors, the fault modes can hardly be identified from the calculated overall transmission error (OTE). In light of this, a novel DD framework based on encoder-measured data is proposed in this work. Specifically, the OTE signal calculated from resampled data are filtered by flexible time synchronous average. A reordered singular values decomposition (RSVD) approach guided by the sparse index L2/L1 norm is then developed for fault-dependent residual OTE extraction. Experimental results validate that the faulty events can be accurately identified by the proposed framework without prior information under different speed conditions for planet gear DD. [ABSTRACT FROM AUTHOR]

By using artificial lightning of standardized Waveform A, this study explored the lightning strike protection (LSP) effect of zirconium carbide (ZrC) and copper (Cu) modified short-carbon-fiber-reinforced boron phenolic resin composites under a current peak of 200 kA. Based on the results of visual observation, micro-morphologies characterization, three-dimensional shapes and X-ray detection, we observed a remarkable LSP effect in this composite, which can be attributed to the high bending strength of the laminated structure, and the well thermal resistance of ZrC. Meanwhile, the addition of Cu powders with concentrations of 10% was demonstrated to enable efficiently withstand the lightning strike and prevent crack propagation since the electrically conductive path. Our findings proposed a promising LSP skin material for the aircraft, which will maintain structural stability under the impact of a lightning strike. [ABSTRACT FROM AUTHOR]

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that can cause acute encephalitis with a high fatality rate. RNA interference (RNAi) is a powerful tool to silence gene expression and a potential therapy for virus infection. In this study, the antiviral ability of eight shRNA expression plasmids targeting different sites of the NS3 and NS4A genes of JEV was determined in BHK21 cells and mice. The pGP-NS3-3 and pGP-NS4A-4 suppressed 93.9% and 82.0% of JEV mRNA in cells, respectively. The virus titer in cells was reduced approximately 950-fold by pretreating with pGP-NS3-4, and 640-fold by pretreating with pGP-NS4A-4. The results of western blot and immunofluorescence analysis showed JEV E protein and viral load in cells were remarkably inhibited by shRNA expression plasmids. The viral load in brains of mice pretreated with pGP-NS3-4 or pGP-NS4A-4 were reduced approximately 2400-fold and 800-fold, respectively, and the survival rate of mice challenged with JEV were 70% and 50%, respectively. However, the antiviral ability of shRNA expression plasmids was decreased over time. This study indicates that RNAi targeting of the NS3 and NS4A genes of JEV can sufficiently inhibit the replication of JEV in vitro and in vivo, and NS3 and NS4A genes might be potential targets of molecular therapy for JEV infection. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced carbon matrix composites (C/C) will be easily oxidized in high temperatures, which will have a great negative effect on their performance. Preparing ultra-high-temperature ceramic (UHTC) coatings is a well-established method to improve the oxidation and ablation resistance of C/C. However, it is time-consuming and costly to obtain these coatings through the traditional experimental method. Motivated by the outstanding performance of machine learning (ML) algorithms in many fields, this study adopts ML algorithms based on historical experimental datasets to build a model. This model will predict the oxidation and ablation resistance, represented by mass ablation rate. For this purpose, variables that affect the mass ablation rate and are easily accessible were used as input features. That includes the chemical composition and essential physics/chemistry properties of coatings and experimental parameters. Seven different ML algorithms were used to establish the model; namely, ridge regression (Ridge), lasso regression (Lasso), kernel ridge regression (KRR), support vector regression (SVR), random forest regression (RFR), AdaBoost regression (ABR), and bagging regression (Bagging). The results show that RFR has the optimal generalization performance with a mean absolute error (MAE) of 0.55, mean-squared error (MSE) of 0.71 and coefficient of determination (R2) of 0.87 on the testing set. SHapley Additive exPlanations (SHAP) analysis of the RFR model explained how these input features affect the mass ablation rate and further provided the critical features for performance prediction. The model established in this study can predict coating performance accurately and accelerate the development of UHTC-coated C/C composites from a data-driven perspective. [ABSTRACT FROM AUTHOR]

• The GARCH family models from time series analysis is introduced for the first time into machine condition monitoring. • Health indicators constructed based on GARCH and EGARCH models demonstrate the capability to detect incipient faults in bearings, verified through two experimental cases. • In accelerated degradation tests, it is established that acoustic emission signals are closely associated with damage evolution. • Acoustic emission technology can be employed for quantitative assessment of bearing damage. Recent progress in digital twin (DT) has significantly contributed to the advancement of predictive maintenance. The interaction of data between physical and virtual models is facilitated through carefully designed health indicators (HIs). Conventional condition monitoring HIs are inadequate for early-stage fault detection and lack the capacity to quantitatively assess defects. In light of this, the paper proposes HIs based on the generalised autoregressive conditional heteroskedasticity (GARCH) family time series model to characterise the evolution of bearings dynamic response, specifically the cyclostationarity of the repetitive transients. The verification of the proposed indicators is assessed using a publicly available vibration dataset and acoustic emission signals acquired from accelerated bearing degradation tests. The result shows that the GARCH oriented indicators can determine the incipient failure earlier than traditional statistical HIs and have the ability to quantify defects. Significantly, the improved Exponential GARCH model-based indicator demonstrates heightened stability throughout the monitoring process. [ABSTRACT FROM AUTHOR]

The acoustic emission (AE) technique is known for its sensitivity to early damage and is well-suited for online condition monitoring of rolling element bearings (REBs) in various industrial application scenarios. Nonetheless, identifying weak faults under varying speed and strong background noise conditions still remains challenging. In addition, the comprehensive modelling of AE signal from faulty REB in electromechanical systems is still a pending issue. In light of this, a well-considered model is firstly developed for the AE signal of faulty REBs in this work. After that, a novel bearing fault diagnosis framework based on semantic segmentation networks is devised. Precisely, the proposed framework consists of three main components: a preprocessing step depending on the signal segmentation algorithm, a diagnosis step using fault fingerprint mapping, and a postprocessing evaluation step supplemented by a density peak clustering (DPC) approach. We evaluate the presented procedures through simulation analysis and an experimental case under varying speed conditions. Meanwhile, the comparison with the original threshold-based fault fingerprint recognition algorithm is also conducted. The comprehensive results demonstrate the efficacy of identifying fault-associated fingerprint feature (FPF), indicating that the proposed framework holds promise for condition monitoring. [ABSTRACT FROM AUTHOR]

Although the inorganic filler modified carbon-phenolic composites are widely used as thermal-structural materials in moderate ablation conditions, it is still unknown whether these composites can be used in extreme environments, such as in high-intensity continuous lasers. To investigate the effect of silicide on ablation behaviors of carbon-phenolic composites, TaSi 2 /ZrSi 2 modified carbon-phenolic composites were fabricated by compression molding and tested in a high-intensity continuous laser. Results showed that TaSi 2 /ZrSi 2 modified carbon-phenolic composites possessed a good ability to resist long-term laser ablation. As the laser ablation time increased, the ablation rate was reduced. When the ablation time was increased to 100 s, the liner ablation rate was only 0.012 mm/s. The formed double ceramic layers with TaZr 2.75 O 8 , Ta 2 O 5 , and SiC as the main phases effectively enhanced the reflectivity of the composites and obstructed laser from entering the interior. The evaporation of the pyrolysis gas and the occurrence of the carbothermal reduction reactions effectively dissipated the deposited energy. The energy dissipation mechanism based on the multi-effect synergy provided the foundation for the modified composites to possess long-term laser resistance. [ABSTRACT FROM AUTHOR]

• Intragenic DNA methylation of StALDH2B7a is modulated by cold stress in potato. • StALDH2B7a expression is correlated to intragenic DNA methylation status. • NbALDH2C4, StALDH2B7a's homolog, scavenges toxic MDA originated from ROS. The aim of this study is to elucidate the role of ALDH2B7a during the response to lower temperature in Solanum tuberosum. This gene was found to have altered intragenic DNA methylation status in our previous reports. A total of 18 orthologs of StALDH2B7a were identified in the S. tuberosum genome, which were then divided into 8 aldehyde dehydrogenase (ALDH) subfamilies. The methylation statuses of four intragenic cytosine sites in intron 5 and exon 6 of genomic StAL DH2B7a were altered by lower temperature stress, resulting in changes in the expression of StALDH2B7a. Silencing of NbALDH2C4 , a homolog of StALDH2B7a in Nicotiana benthamiana , resulted in plants which were sensitive to lower temperature and accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). These data suggested that the expression of StALDH2B7a was upregulated by alteration of its intragenic cytosine methylation status during lower temperature stress, and additional StALDH2B7a enzymes scavenged excess aldehydes resulting from ROS in a response to cold stress in potato. Our study expands the understanding of the mechanisms involved in plant responses to lower temperature, and provides a new gene source to improve potato tolerance to cold stress in northern China, where lower temperature is one of the key limiting factors for crop production. [ABSTRACT FROM AUTHOR]

• In S. suis, introduction of a codY mutant into ΔrelAΔrelQ strain reduced the expression of virulence factors. • The ΔcodYΔrelAΔrelQ was highly attenuated in S. suis. • GTP is not a ligand of CodY in S. suis. • CodY could interacted with the promoter of relA and positively regulate the expression of relA in S. suis. CodY and (p)ppGpp synthetases are two important global regulators of bacteria. In some pathogens, such as Listeria monocytogenes , the GTP pool links these two regulatory systems, and introducing a codY mutant into the Δ relA strain restored the pathogenicity of the attenuated Δ relA mutant. In previous studies, we identified the (p)ppGpp synthetases (RelA and RelQ) and CodY of Streptococcus suis. To understand the interrelationships between these two regulators in S. suis , a Δ relA Δ relQ Δ codY mutant was constructed, and its growth, morphology, and pathogenicity were evaluated. Compared with Δ relA Δ relQ , Δ codY , its growth was very slow, but its chain length was partly restored to the wild-type length and its capsule became thick and rough. The adherence, invasion ability, and resistance to whole-blood killing in vitro of Δ relA Δ relQ Δ codY and its lethality and colonization ability in mice were clearly reduced, which differs from the effects of these mutations in L. monocytogenes. An analysis of gene expression showed that CodY interacted with the relA promoter in a GTP-independent manner to positively regulate the expression of relA. The introduction of a codY mutant into the Δ relA Δ relQ strain further reduced the expression of virulence factors, which suggests a novel interaction between the (p)ppGpp synthetases and CodY. This study extends our understanding of the relationship between the (p)ppGpp-mediated stringent response and the regulation of CodY in S. suis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ablation mechanism of metamaterials under high-energy continuous-wave laser irradiation was for the first time revealed. • The microwave absorption performance of metamaterials under extreme laser damage conditions was firstly deeply investigated. Metamaterials, typically consisting of sub-wavelength metal-atom arrays and a dielectric layer matrix such as glass fiber reinforced epoxy resin (FR-4), have been widely used in the field of stealth equipment due to their good electromagnetic parameter designability and strong absorption for electromagnetic waves at specific frequencies. In offensive and defensive confrontations, laser weapons pose a serious threat to the survival of stealth equipment. However, the interaction mechanism between the metamaterials and laser and the effect of laser ablation on microwave absorption performance are still unclear. In this work, we firstly irradiated the double arc-shaped Cu-atom array/FR-4 matrix metamaterials by using a high-energy continuous-wave laser and studied the interaction and response mechanism between them. The high temperature caused by laser irradiation leads to the melting of the metal atoms and the pyrolysis of the resin matrix. By simulating and testing the reflection loss of the metamaterials before and after irradiation, we found that the resin pyrolysis products strongly affect the impedance matching characteristics and reduce the microwave absorption properties significantly in extreme cases. Our findings help deeply understand the interaction between the metamaterials and the laser and will show guidance in the applications involving laser-metamaterial interactions. [ABSTRACT FROM AUTHOR]