Search

Optical frequency domain reflectometry (OFDR) is an attractive locating technology for distributed acoustic sensor (DAS) due to its high spatial resolution, but the detectable bandwidth of vibration is very limited up to date, because high frequency vibration will induce time-variant beat frequency shift within the probe, which can deteriorate or even invalidate the demodulation algorithm. In this work, the influence of vibration induced beat frequency shift in OFDR is analyzed and assessed by the crosstalk power spectral density (PSD). Then an adaptive two-dimensional cross-correlation algorithm is proposed for beat frequency shift compensation, in which the instantaneous beat frequency shift within the probe is estimated and compensated for precise strain demodulation. In the experiment, an $18 \text{-}kHz$ vibration signal is successfully detected with spatial resolution of 12 $\rm cm$ and strain resolution of $594\;\rm p\varepsilon/\sqrt{Hz}$, whose frequency is an order of magnitude higher than previous works. The proposed beat frequency shift compensation algorithm is evaluated in different conditions, and a suppression of crosstalk PSD up to $40.5\rm \ dB$ is proved.

High-temperature ablation is a common failure phenomenon that limits the service life of the transmission parts on heavy-duty machines used in heavy load, high temperature, high shock conditions due to in-sufficient supply of lubricating oil and grease. Traditional self-lubricating coatings prepared by inorganic, organic or organic-inorganic hybrid methods are prone to be oxidated at high temperatures to lose their friction reducing function, so that it is difficult to meet the engineering requirements of high-temperature lubrication. We design viscoelastic polymer coatings by a high-temperature self-lubricating and wear-resistant strategy. Polytetrafluoroethylene (PTFE, Tm= 329 °C) and polyphenylene sulfide (PPS, Tg= 84 °C, Tm= 283 °C) are used to prepare a PTFE/PPS polymer alloy coating. As the temperature increases from 25 to 300 °C, the PTFE/PPS coating softens from glass state to viscoelastic state and viscous flow state, which is owing to the thermodynamic transformation characteristic of the PPS component. Additionally the friction coefficient (µ) decreased from 0.096 to 0.042 with the increasing of temperature from 25 to 300 °C. The mechanism of mechanical deformation and surface morphology evolution for the PTFE/PPS coating under the multi-field coupling action of temperature (T), temperature–centrifugal force (T–Fω), temperature–centrifugal force–shearing force (T–Fω–Fτ) were investigated. The physical model of “thermoviscoelasticity driven solid–liquid interface reducing friction” is proposed to clarify the self-lubricating mechanism determined by the high-temperature viscoelastic properties of polymers. The high-temperature adjusts the viscosity (η) of the coating, increases interface slipping and intensifies shear deformation (τ), reducing the friction coefficient. The result is expected to provide a new idea for designing anti-ablation coatings served in high temperature friction and wear conditions.

A green and efficient visible-light induced functionalization of anilines under mild conditions has been reported. Utilizing nontoxic, cost-effective, and water-soluble diacetyl as photosensitizer and acetylating reagent, and water as the solvent, a variety of anilines were converted into the corresponding aryl ketones, iodides, and bromides. With advantages of environmentally friendly conditions, simple operation, broad substrate scope, and functional group tolerance, this reaction represents a valuable method in organic synthesis.

Background: Non-small cell lung carcinoma (NSCLC) accounts for 80% of all lung cancer cases, which have been a leading cause of morbidity and mortality worldwide. Previous studies demonstrated that centromere proteins were dysregulated and involved in regulating the tumorigenesis and development of human cancers. However, the roles of centromere protein family members in NSCLC remained to be further elucidated. Objective: The present study aimed to explore the roles of centromere protein family members in NSCLC. Methods: GEPIA (http://gepia.cancer-pku.cn/) was used to analyze the target’s expression between normal and human cancers. We explored the prognostic value of centromere proteins in NSCLC using the Kaplan–Meier plotter (http://kmplot.com). The protein-protein interaction among centromere proteins was determined using GeneMANIA (http://www.genemania.org). TISIDB (http://cis.hku.hk/TISIDB) database was used to detect the relationship between centromere protein expression and clinical stages, lymphocytes, immunomodulators and chemokines in NSCLC. The DAVID database (https://david.ncifcrf.gov) was used to detect potential roles of CENPK using its co-expressing genes. Results: The present study for the first time showed that centromere protein family members including CENPA, CENPF, CENPH, CENPI, CENPK, CENPM, CENPN, CENPO, CENPQ, CENPU were dysregulated and correlated to the poor prognosis of patients with LUAD. CENPK showed the greatest correlation with the prognosis of patients with NSCLC. We found that CENPK was significantly highly expressed in LUAD samples and overexpression of CENPK was remarkably correlated to the shorter OS and DFS in patients with a different stage of NSCLC. Of note, this study for the first time showed that CENPK was significantly correlated to the lymphocytes and immunomodulators using the TISIDB database. Conclusion: In summary, CENPK can serve as a novel biomarker for the diagnosis of patients with NSCLC.

A mathematical model for the flowrate and rotation speed of RCP during idling was established. The numerical calculation method and dimensionless method were used to analyze the flow, head, torque and pressure and speed changes under idle conditions. Regularity, using the Qcriterion vortex identification judgment method combined with surface flow spectrum morphology analysis to diagnose the vortex dynamic characteristics on RCP blade. On impeller blade, there is two oscillations in the pressure ratio on pressure surface in blade outlet region. The velocity on the suction surface is two times more oscillating than the inlet of blade, and there is an intersection with the velocity ratio curve on pressure surface. On blade of guide vane, the pressure ratio increases along the inlet to outlet direction, and the speed ratio decreases with the increase of idle time. There is a vortex that rotates counterclockwise on the suction surface, and the streamline on the suction surface of blade is subjected to the entrainment and blocking action of the vortex creates a large reverse flow in the main flow region. There are two vortices at the outlet of guide vane suction side and the vortices are in opposite directions.

Anti-icing materials have become increasingly urgent for many fields such as power transmission, aviation, energy, telecommunications, and so on. Bionic lotus hydrophobic surfaces with hierarchical micro-/nanostructures show good potential of delaying ice formation; however, their icephobicity (deicing ability) has been controversial. It is mainly attributed to lack of deep understanding of the correlation between micro-/nanoscale structures, wettability, and icephobicity, as well as effective methods for evaluating the deicing ability close to natural environments. In this article, the natural deicing ability is innovatively proposed on the basis of ice adhesion and the influence of microscale structure evolution on dynamic wetting and deicing ability (both ice adhesion strength and natural deicing time) was systematically investigated. Interestingly, different modes (sticky or slippery) were found in natural deicing of hierarchical hydrophobic surfaces, although their ice adhesion strength was higher than that of smooth surfaces. The mechanism was analyzed from three aspects: mechanics, heat transfer, and dynamic wetting. It is highlighted that the sliding of melted interface is not equal to water droplet sliding (dynamic wetting) before freezing or after deicing but significantly depends on the microscale structure. The fundamental understanding on natural deicing of bionic hydrophobic surfaces will open up a new window for developing new anti-icing materials and technology.

Convolutional neural networks (CNNs) have wide applications in pattern recognition and image processing. Despite recent advances, much remains to be done for CNNs to learn a better representation of image samples. Therefore, constant optimizations should be provided on CNNs. To achieve a good performance on classification, intuitively, samples' interclass separability, or intraclass compactness should be simultaneously maximized. Accordingly, in this paper, we propose a new network, named separability and compactness network (SCNet) to rectify this problem. SCNet minimizes the softmax loss and the distance between features of samples from the same class under a jointly supervised framework, resulting in simultaneous maximization of interclass separability and intraclass compactness of samples. Furthermore, considering the convenience and the efficiency of the cosine similarity in face recognition tasks, we incorporate it into SCNet's distance metric to enable sample features from the same class to line up in the same direction and those from different classes to have a large angle of separation. We apply SCNet to three different tasks: visual classification, face recognition, and image superresolution. Experiments on both public data sets and real-world satellite images validate the effectiveness of our SCNet.

Nematic liquid crystals (NLCs) offer remarkable opportunities to direct colloids to form complex structures. The elastic energy field that dictates colloid interactions is determined by the NLC director field, which is sensitive to and can be controlled by boundaries including vessel walls and colloid surfaces. By molding the director field via liquid-crystal alignment on these surfaces, elastic energy landscapes can be defined to drive structure formation. We focus on colloids in otherwise defect-free director fields formed near undulating walls. Colloids can be driven along prescribed paths and directed to well-defined docking sites on such wavy boundaries. Colloids that impose strong alignment generate topologically required companion defects. Configurations for homeotropic colloids include a dipolar structure formed by the colloid and its companion hedgehog defect or a quadrupolar structure formed by the colloid and its companion Saturn ring. Adjacent to wavy walls with wavelengths larger than the colloid diameter, spherical particles are attracted to locations along the wall with distortions in the nematic director field that complement those from the colloid. This is the basis of lock-and-key interactions. Here, we study ellipsoidal colloids with homeotropic anchoring near complex undulating walls. The walls impose distortions that decay with distance from the wall to a uniform director in the far field. Ellipsoids form dipolar defect configurations with the colloid’s major axis aligned with the far field director. Two distinct quadrupolar defect structures also form, stabilized by confinement; these include the Saturn I configuration with the ellipsoid’s major axis aligned with the far field director and the Saturn II configuration with the major axis perpendicular to the far field director. The ellipsoid orientation varies only weakly in bulk and near undulating walls. All configurations are attracted to walls with long, shallow waves. However, for walls with wavelengths that are small compared to the colloid length, Saturn II is repelled, allowing selective docking of aligned objects. Deep, narrow wells prompt the insertion of a vertical ellipsoid. By introducing an opening at the bottom of such a deep well, we study colloids within pores that connect two domains. Ellipsoids with different aspect ratios find different equilibrium positions. An ellipsoid of the right dimension and aspect ratio can plug the pore, creating a class of 2D selective membranes.

The ability of cells to reorganize in response to external stimuli is important in areas ranging from morphogenesis to tissue engineering. While nematic order is common in biological tissues, it typically only extends to small regions of cells interacting via steric repulsion. On isotropic substrates, elongated cells can co-align due to steric effects, forming ordered but randomly oriented finite-size domains. However, we have discovered that flat substrates with nematic order can induce global nematic alignment of dense, spindle-like cells, thereby influencing cell organization and collective motion and driving alignment on the scale of the entire tissue. Remarkably, single cells are not sensitive to the substrate’s anisotropy. Rather, the emergence of global nematic order is a collective phenomenon that requires both steric effects and molecular-scale anisotropy of the substrate. To quantify the rich set of behaviours afforded by this system, we analyse velocity, positional and orientational correlations for several thousand cells over days. The establishment of global order is facilitated by enhanced cell division along the substrate’s nematic axis, and associated extensile stresses that restructure the cells’ actomyosin networks. Our work provides a new understanding of the dynamics of cellular remodelling and organization among weakly interacting cells.

Anti-icing surfaces/interfaces are of considerable importance in various engineering fields under natural freezing environment. Although superhydrophobic self-cleaning surfaces show good anti-icing potentials, promotion of these surfaces in engineering applications seems to enter a “bottleneck” stage. One of the key issues is the intrinsic relationship between superhydrophobicity and icephobicity is unclear, and the dynamic action mechanism of “air cushion” (a key internal factor for superhydrophobicity) on icing suppression was largely ignored. Here we report that icing inhibition (i.e., icing-delay) of self-cleaning surfaces is mainly ascribed to air cushion and its convection. We experimentally found air cushion on the porous self-cleaning coating under vacuum environments and on the water/ice-coating interface at low temperatures. The icing-delay performances of porous self-cleaning surfaces compared with bare substrate, up to 10–40 min under 0 to ∼−4 °C environments close to freezing rain, have been accurately real-time recorded by a novel synergy method including high-speed photography and strain sensing voltage. Based on the experimental results, we innovatively propose a physical model of “air cushion convection inhibiting icing”, which envisages both the static action of trapped air pocket without air flow and dynamic action of air cushion convection. Gibbs free energy of water droplets increased with the entropy of air derived from heat and mass transfer between warmer air underneath water droplets and colder surrounding air, resulting in remarkable ice nucleation delay. Only when air cushion convection disappears can ice nucleation be triggered on suitable Gibbs free energy conditions. The fundamental understanding of air cushion on anti-icing is an important step toward designing optimal anti-icing surfaces for practical engineering application.

Stroke is a type of cerebrovascular disease that significantly endangers human health and lowers quality of life. This understandably places a heavy burden on society and families. In recent years, intestinal flora has attracted increasing attention from scholars worldwide, and its association with ischemic stroke is becoming a hot topic of research amongst researchers in field of stroke. After suffering from a stroke, intestinal microbial dysbiosis leads to increased intestinal permeability and activation of the intestinal immune system, which in turn leads to ectopic intestinal bacteria and pro-inflammatory cells that enter brain tissue through the damaged blood-brain barrier. This exacerbates ischemia-reperfusion injury. Interestingly, after a stroke, some metabolites produced by the intestinal flora attenuate ischemia-reperfusion injury by suppressing the post-stroke inflammatory response and promotes the repair of neurological function. Here we elucidate the changes in gut flora after occurrence of a stroke and highlight the immunomodulatory processes of the post-stroke gut flora.

Coaxial cables for data transmission are ubiquitous in telecommunications, aerospace, automotive, and robotics industries. Yet, the metals used to make commercial cables are unsuitably heavy and stiff. These undesirable traits are particularly problematic in aerospace applications, where weight is at a premium and flexibility is necessary to conform with the distributed layout of electronic components in satellites and aircraft. The cable outer conductor (OC) is usually the heaviest component of modern data cables; therefore, exchanging the conventional metallic OC for lower weight materials with comparable transmission characteristics is highly desirable. Carbon nanotubes (CNTs) have recently been proposed to replace the metal components in coaxial cables; however, signal attenuation was too high in prototypes produced so far. Here, we fabricate the OC of coaxial data cables by directly coating a solution of CNTs in chlorosulfonic acid (CSA) onto the cable inner dielectric. This coating has an electrical conductivity that is approximately 2 orders of magnitude greater than the best CNT OC reported in the literature to date. This high conductivity makes CNT coaxial cables an attractive alternative to commercial cables with a metal (tin-coated copper) OC, providing comparable cable attenuation and mechanical durability with a 97% lower component mass.