Obtaining the vibration stress of fan rotor blades under actual working conditions through flight tests is a necessary means to carry out design verification and optimization improvement of turbofan ...engine. Taking the high bypass ratio turbofan engine as research object, installed ground and flight tests were carried out. The vibration characteristics and stress distribution of the fan blade were obtained by direct measurement means of strain gauge, and the air-ground characteristics of the test data were compared and analyzed. The results show that under the steady state, the vibration stress level of fan blade in ground test is significantly higher than that in flight test; There is a significant difference in frequency distribution of excitation factors on fan blade in the ground and flight tests.
WiFi fingerprinting-based indoor positioning system (IPS) using received signal strength (RSS) has been considered to be one solution for indoor positioning. However, there are two major bottlenecks ...that hamper its large-scale implementation. One widely recognized problem is the construction of a proper fingerprint database with high efficiency and accuracy. Second is to improve the online positioning accuracy on the basis of the fingerprint database. To address these issues comprehensively, this paper proposes a novel system-Digital navigation center IPS (DncIPS), an IPS that enables automatic online radio map construction, and step-by-step positioning, aiming for the high-accuracy RSS estimation and high-precision positioning. DncIPS can capture WiFi data packets transmitted in WiFi traffic so that they obtain the MAC addresses, frequency, and RSS of any WiFi access point (AP) at any point. DncIPS uses Gaussian process regression model based on a fireworks algorithm to approximate the RSS distribution of an indoor environment and to estimate the location of APs increasing the flexibility of DncIPS work environment. This system also consists of a coarse localizer detecting the outliers and dividing clustering area and a fine localizer followed to improve the online positioning accuracy. Extensive experiments results indicate the proposed system DncIPS leads to improvement on radio map updating and localization accuracy.
Alterations of symbiosis between microbiota and intestinal epithelial cells (IEC) are associated with intestinal and systemic pathologies. Interactions between bacterial products (MAMPs) and ...Toll-like receptors (TLRs) are known to be mandatory for IEC homeostasis, but how TLRs may time homeostatic functions with circadian changes is unknown. Our functional and molecular dissections of the IEC circadian clock demonstrate that its integrity is required for microbiota-IEC dialog. In IEC, the antiphasic expression of the RORα activator and RevErbα repressor clock output regulators generates a circadian rhythmic TLR expression that converts the temporally arrhythmic microbiota signaling into circadian rhythmic JNK and IKKβ activities, which prevents RevErbα activation by PPARα that would disrupt the circadian clock. Moreover, through activation of AP1 and NF-κB, these activities, together with RORα and RevErbα, enable timing homeostatic functions of numerous genes with IEC circadian events. Interestingly, microbiota signaling deficiencies induce a prediabetic syndrome due to ileal corticosterone overproduction consequent to clock disruption.
Display omitted
•Symbiosis between gut microbiota and IEC requires integrity of the circadian clock•Clock and TLRs convert arrhythmic bacterial signals into circadian gene expression•Homeostatic gene expression via RORE, NF-κB, and AP-1 binding sites requires the clock•Lack of microbiota leads to ileal glucocorticoid overproduction and prediabetes
Microbiota regulate the expression of clock components in intestinal epithelial cells, whereas clock genes regulate the expression of receptors (such as TLRs) that mediate signaling between microbiota and intestinal cells. This interplay imposes a circadian rhythm on intestinal genes regulated by arrhythmic microbiota.
The design and characterization of purely organic room‐temperature phosphorescent (RTP) materials for optoelectronic applications is currently the focus of research in the field of organic ...electronics. Particularly, with the merits of preparation controllability and modulation flexibility, host–guest material systems are encouraging candidates that can prepare high‐performance RTP materials. By regulating the interaction between host and guest molecules, it can effectively control the quantum efficiency, luminescent lifetime, and color of host–guest RTP materials, and even produce RTP emission with stimuli‐responsive features, holding tremendous potential in diverse applications such as encryption and anti‐counterfeiting, organic light‐emitting diodes, sensing, optical recording, etc. Here a roundup of rapid achievement in construction strategies, molecule systems, and diversity of applications of host–guest material systems is outlined. Intrinsic correlations between the molecular properties and a survey of recent significant advances in the development of host–guest RTP materials divided into three systems including rigid matrix, exciplex, and sensitization are presented. Providing an insightful understanding of host–guest RTP materials and offering a promising platform for high throughput screening of RTP systems with inherent advantages of simple material preparation, low‐cost, versatile resource, and controllably modulated properties for a wide range of applications is intended.
Host–guest room temperature phosphorescence (RTP) materials have revolutionized the understandings of organic optoelectronics, leading to significant advances in constructing advanced applications. Explanative account is provided for systematizing the knowledge of host–guest RTP materials, with an emphasis on construction strategies, molecular structures and properties, and diverse applications.
Developing high-efficient afterglow from metal-free organic molecules remains a formidable challenge due to the intrinsically spin-forbidden phosphorescence emission nature of organic afterglow, and ...only a few examples exhibit afterglow efficiency over 10%. Here, we demonstrate that the organic afterglow can be enhanced dramatically by thermally activated processes to release the excitons on the stabilized triplet state (T
) to the lowest triplet state (T
) and to the singlet excited state (S
) for spin-allowed emission. Designed in a twisted donor-acceptor architecture with small singlet-triplet splitting energy and shallow exciton trapping depth, the thermally activated organic afterglow shows an efficiency up to 45%. This afterglow is an extraordinary tri-mode emission at room temperature from the radiative decays of S
, T
, and T
. With the highest afterglow efficiency reported so far, the tri-mode afterglow represents an important concept advance in designing high-efficient organic afterglow materials through facilitating thermally activated release of stabilized triplet excitons.
Harvesting the narrow bandgap excitons of charge‐transfer (CT) complexes for the achievement of near‐infrared (NIR) emission has attracted intensive attention for its fundamental importance and ...practical application. Herein, the triphenylene (TP)‐2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) CT organic complex is designed and fabricated via the supramolecular self‐assembly process, which demonstrates the NIR emission with a maximum peak of 770 nm and a photoluminescence quantum yield (PLQY) of 5.4%. The segregated stacking mode of TP‐F4TCNQ CT complex based on the multiple types of intermolecular interaction has a low CT degree of 0.00103 and a small counter pitch angle of 40° between F4TCNQ and TP molecules, which breaks the forbidden electronic transitions of CT state, resulting in the effective NIR emission. Acting as the promising candidates for the active optical waveguide in the NIR region beyond 760 nm, the self‐assembled TP‐F4TCNQ single‐crystalline organic microwires display an ultralow optical‐loss coefficient of 0.060 dB µm−1. This work holds considerable insights for the exploration of novel NIR‐emissive organic materials via an universal “cocrystal engineering” strategy.
Through changing mixed stacking into segregated stacking mode, triphenylene (TP)‐2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) charge‐transfer (CT) complex demonstrates a low CT degree and a small counter pitch angle between TP and F4TCNQ molecules, benefiting for breaking the forbidden electronic transitions of CT state for realizing the near‐infrared emission with a maximum peak of 770 nm and a photoluminescence quantum yield of 5.4%.
Lab‐on‐a‐chip systems aim to integrate laboratory operations on a miniaturized device with broad application prospects in the field of point‐of‐care testing. However, bulky peripheral power ...resources, such as high‐voltage supplies, function generators, and amplifiers, hamper the commercialization of the system. In this work, a portable, self‐powered microparticle manipulation platform based on triboelectrically driven dielectrophoresis (DEP) is reported. A rotary freestanding triboelectric nanogenerator (RF‐TENG) and rectifier/filter circuit supply a high‐voltage direct‐current signal to form a non‐uniform electric field within the microchannel, realizing controllable actuation of the microparticles through DEP. The operating mechanism of this platform and the control performance of the moving particles are systematically studied and analyzed. Randomly distributed particles converge in a row after passing through the serpentine channel and various particles are separated owing to the different DEP forces. Ultimately, the high‐efficiency separation of live and dead yeast cells is achieved using this platform. RF‐TENG as the power source for lab‐on‐a‐chip exhibits better safety and portability than traditional high‐voltage power sources. This study presents a promising solution for the commercialization of lab‐on‐a‐chip.
A self‐powered DEP microparticle manipulation platform based on a triboelectric nanogenerator (TENG) is proposed, which performs high‐efficiency cell separation. This work provides an ideal scheme for improving the portability of microfluidic chips and is beneficial to the commercialization of lab‐on‐a‐chip systems.
Liver fibrosis is an intrinsic repair process of chronic injury with excessive deposition of extracellular matrix. As an early stage of various liver diseases, liver fibrosis is a reversible ...pathological process. Therefore, if not being controlled in time, liver fibrosis will evolve into cirrhosis, liver failure, and liver cancer. It has been demonstrated that hepatic stellate cells (HSCs) play a crucial role in the formation of liver fibrosis. In particular, the activation of HSCs is a key step for liver fibrosis. Recent researches have suggested that autophagy and inflammasome have biological effect on HSC activation. Herein, we review current studies about the impact of autophagy and NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome on liver fibrosis and the underlying mechanisms.
The tip clearance of high-pressure turbine rotor is a key parameter for the performance and control of turbofan engine. It is of great significance to master the variation law of tip clearance for ...evaluating the working efficiency and performance attenuation of turbofan engine. The high-frequency dynamic analysis method based on time-frequency analysis is established. The variation law of high-pressure turbine tip clearance with engine state is obtained, and the influencing factors are analysed by simulation. The test results show that the variation law of the tip clearance of the high-pressure is consistent with the design, that is about 0∼3mm. The tip clearance of the high-pressure turbine is greatly affected by the rotor vibration. It means that we can monitor vibration of the rotor by monitoring changes in tip clearance. Real-time measurement and control adjustment should be carried out in the flight test to improve the working efficiency of the engine.
PDF
