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In the process of responding to public health emergencies, the government should promote effective communication with the public and further unblock the channels of communication between the government and the public. Government press conferences are an important channel for the government to communicate with the outside world and an important tool for the government to respond to public health emergencies. The government should make reasonable use of press conferences to actively respond to social concerns, promote the positive function of public opinion, and improve the ability to respond to sudden public health forgetfulness so as to promote the formation of a synergy of social governance. Based on the theory of political communication, this paper focuses on the practical principles and operational risks of government press conferences under public health events and puts forward governance ideas to standardize the release process, strengthen interaction and cooperation, and improve emergency response capacity, so as to achieve emergency management capabilities of government press conferences under public health emergencies.

Spermatogenesis is a finely regulated process of germ cell proliferation and differentiation that leads to the production of sperm in seminiferous tubules. Although the mammalian target of rapamycin (mTOR) signaling pathway is crucial for spermatogenesis in mammals, its functions and molecular mechanisms in spermatogenesis remain largely unknown in nonmammalian species, particularly in Crustacea. In this study, we first identified es-Raptor (the core component of mTOR complex 1) and es-Rictor (the core component of mTOR complex 2) from the testis of Eriocheir sinensis. Dynamic localization of es-Raptor and es-Rictor implied that these proteins were indispensable for the spermatogenesis of E. sinensis. Furthermore, es-Raptor and es-Rictor knockdown results showed that the mature sperm failed to be released, causing almost empty lumens in the testis. We investigated the reasons for these effects and found that the actin-based cytoskeleton was disrupted in the knockdown groups. In addition, the integrity of the testis barrier (similar to the blood-testis barrier in mammals) was impaired and affected the expression of cell junction proteins. Further study revealed that es-Raptor and es-Rictor may regulate spermatogenesis via both mTORC1- and mTORC2-dependent mechanisms that involve es-rpS6 and es-Akt/es-PKC, respectively. Moreover, to explore the testis barrier in E. sinensis, we established a cadmium chloride (CdCl

Long duration space flight would cause serious bone loss and bone quality deterioration. For better understanding the underlying mechanism and countermeasures, it is necessary to know the structural-mechanical relationship of the tissue. Bone is a hierarchically structured composite material with up to seven hierarchical levels of organization. At different length scales, it has distinct mechanical behaviors. In a previous study, we studied the effects of microgravity on the nano-indentation properties of bone, showing that microgravity has some effects on the nano-indentation properties of bone. However, this result obtained at nanoscopic length scale is not consistent with the previous observations that microgravity would cause deterioration in the bulk mechanical property of bone at higher structural hierarchies. To address this issue, we used micro-indentation technique in this study to examine the effects of microgravity on the mechanical property of bone at microscopic length scale. After 21 days tail suspension, the elastic modulus (E), hardness (H), and E/H ratio of rat femur were significantly decreased and such changes were different between cortical and trabecular bone. This result was similar with those of three-point bending test, but different from those of nano-indentation test. The results suggest that the decrease of macro-mechanical property under unloading-simulated microgravity (SMG) condition is most likely due to changes at microstructural level (across lamellae) instead of at sub-micron or nanoscopic length scales (within lamellae).

Numerous studies have shown that the blood of cancer patients are generally in hypercoagulable statement. The aim of the present research is to study the relationships of plasma fibrinogen (Fbg) levels with clinicopathological stages (CS) and tumor markers of non-small cell lung cancer (NSCLC). Baseline information, plasma Fbg levels, CS, and expression level of tumor markers were collected from medical records retrospectively. Unitary linear regression was used to analyze the relationships between continuous variables and Fbg, and multiple linear regression was used to analyze the relationships between categorical variables and Fbg. National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology (Version 4) for NSCLC were adopted to evaluate CS. A total of 652 NSCLC patients were included. Compared with the females, male patients had higher mean plasma Fbg levels (P

Thermal barrier coatings(TBCs) has been extensively used on hot section components of gas turbine engine, especially turbine blades. Young’s modulus of TBCs is a significant mechanical parameter in life prediction research of turbine blades, but it is hard to measure the EB-PVD thermal barrier coatings by conventional tensile/compression method for its brittleness and porous microstructure. Therefore, Young’s modulus mathematical model of double-layer beam structure specimen was deduced on the basis of the first-order beam bending vibration equation and composite beam bending equation. An experimental platform with dynamic signal acquisition system was set up for measuring Young's modulus of thermal barrier coatings under high temperature. Young's modulus of ceramic coat was measured from ambient temperature to 1100°C to provide material data for subsequent research on life prediction of turbine blades with thermal barrier coatings.

Vibration, especially at low magnitude and high frequency (LMHF), was demonstrated to be anabolic for bone, but how the LMHF vibration signal is perceived by osteocytes is not fully studied. On the other hand, the mechanotransduction of osteocytes under shear stress has been scientists' primary focus for years. Due to the small strain caused by low-magnitude vibration, whether the previous explanation for shear stress will still work for LMHF vibration is unknown. In this study, a finite element method (FEM) model based on the real geometrical shape of an osteocyte was built to compare the mechanical behaviors of osteocytes under LMHF vibration and shear stress. The bio-response of osteocytes to vibration under different frequencies, including the secretion of soluble factors and the concentration of intracellular calcium, were studied. The regulating effect of the conditioned medium (CM) from vibrated osteocytes on osteoblasts was also studied. The FEM analysis result showed the cell membrane deformation under LMHF vibration was very small (with a peak value of 1.09%) as compared to the deformation caused by shear stress (with a peak value of 6.65%). The F-actin stress fibers of osteocytes were reorganized, especially on the nucleus periphery after LMHF vibration. The vibration at 30 Hz has a promoting effect on osteocytes and the osteogenesis of osteoblasts, whereas vibration at 90 Hz was suppressive. These results lead to a conclusion that the bio-response of osteocytes to LMHF vibration is frequency-dependent and is more related to the cytoskeleton on nuclear periphery rather than the membrane deformation.

The electron beam-physical vapor deposition (EB-PVD) coatings were selected to analyze the fatigue life. Firstly the failure mechanisms of oxidation and thermal fatigue of TBCs were considered together. The weight of thermally grown oxide (TGO) were measured during oxidation experiments and modeled. Thermal fatigue experiments were induced by thermal mismatched stress and thermal fatigue with holding time. The failure mechanism was obtained by the finite element analyses. The life prediction model was modified by the shear and normal strain range close to the interface of the top coat and TGO. Based on the experiment data, the life prediction model of thermal fatigue of TBCs was set up for EB-PVD coatings. Finally, using the life prediction model, the life of TBCs was predicted under the designed load case. The life prediction model was verified and all experiment data fall into the factor of 3 scatter band.

External surface cracks can occur in cylindrical vessels due to damage and propagate in the manufacturing process and during service life. Most of research focuses on stress intensity factors for surface cracks with low aspect ratios, i.e., a/c ≤1.0. Situation may well arise where the aspect ratio of cracks is larger than one. An external longitudinal surface crack is assumed to be subjected to different types of hoop stress distributions acting perpendicular to the crack faces. The stress intensity factors (SIFs) along the crack front were determined through the three-dimensional finite element method. Then these results are used to compute approximate values of SIFs in the case of complex loadings by employing both the superposition principle and the power series expansions of the actual hoop stresses. It is found that the maximum stress intensity factor for external surface cracks with high aspect ratio occurs at different point to that with low aspect ratio.

Double Inverted pendulum as an important object of study on robotics and aviation field, is also a major platform for teaching and scientific research.Usually double Inverted pendulum modeling is usually will be linearized processing system, ignoring the effect of the angle of system. But the realization of double inverted pendulum is a nonlinear system, the angle affect the stability control. From the actual situation of double Inverted pendulum motion, double Inverted pendulum system of the input space is divided into 9 sub-space, by T-S fuzzy and feedback gain matrix to select the corresponding state equation, making the system more close to its dynamic performance. The multi mode adaptive control and T-S fuzzy method of combining the successful implementation of double inverted pendulum system simulation and real-time control.The number of rules they use far less than Mamdani fuzzy, but also successfully resolved the fuzzy control algorithm due to the presence of multiple variables and the resulting "rule explosion problem".

Gear rotor systems are widely used in many automotive, aerospace and marine applications. Dynamic analysis of gear rotor systems is essential in describing noise and durability characteristics. Using ANSYS software, a finite-element model for a gear rotor system on flexible bearing has been developed, with MARTIX element, beam element and mass element simulating mesh-couple relation and support bearing, shaft and gear individually. The dynamic coupling among the axial, transverse, tensional and rotational motions of gears are considered in the model. The harmonic analysis and forced response of the system were analyzed. The effect of bearing compliances, shaft compliances and helix angle on system dynamics were investigated. The feasibility of the method was verified, the model and result can be used for dynamic design of gear rotor system.

Thermal barrier coatings (TBCs) systems are widely used in gas turbines. However, the potential of thermal barrier coatings cannot be fully exerted due to the lack of a reliable life prediction of the coating, which requires the better understanding of the TBC failure mechanisms. In the present work, the failure mechanism of atmospheric plasma spraying (APS) was studied. The FE simulation was adopted to explore the stress distribution in TBC, and then thermal fatigue experiments were carried out. Two advanced constitutive models have been developed and implemented into ABAQUS through UMAT in order to simulate the mechanical behaviors of TBC system under thermal cyclic load. The constitutive model for ceramic top coat (TC) could model the non-symmetry of tensile and compressive loading, and viscoplastic constitutive model was used for the substrate. The stress distributions along the interfaces between TC and bond coat (BC) were obtained. For as-deposited APS–TBC, the thermally grown oxide (TGO) is very thin, which is less than 0.3 μm, the small cracks only initiate in the ceramic top coat not in TGO. The crack imitates at the off-peak and propagates to the peak in TC. Finally the crack will have tendency to occur in internal top coat and be spallation. Meanwhile, the FE simulation and experiment data can provide a basis to develop a more accurate life prediction model.

The blisk (bladed disk) is a new structural component of the modern aero-engine and plays an important role in improving its performance. Ti-6Al-4V alloy joints welded by electron beam have been widely used for compressor blisk in advanced aero engine. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded structure by electron beam welding (EBW) for failure analysis and structure design of blisk. Microstructure of Ti-6Al-4V welded structure by EBW was investigated by microscopic observation and micro indentation testing. Experiment results show grain coarsening in fusion zone (FZ) and heat affected zone (HAZ) appears large gradient organization structure, which presents significant local heterogeneity. On the centerline perpendicular to the welding direction, Vickers microhardness was measured in increments of 1mm, 0.5mm, 0.25mm and 0.1mm. Due to the presence of martensite, microhardness of the fusion zone is about 20% higher than that of the base material. The size of joints in different regions was acquired, 2.5 to 3.0-mm-wide in FZ and about 0.7-mm-wide in HAZ respectively. Three different types of EBW samples were designed for tensile test, including welded structure, welded joint and base material. Three different stress-strain curves of specimens were acquired, including welded joint. The experiment data indicates that the tensile strength of welded joints is 8% more than that of the base metal.

Forged Ti-6Al-4V welded structure by electronic beam welding (EBW) as integrally bladed disk (blisk) structure in advanced aero-engine has been widely applied. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded joints by EBW for failure analysis and structure design of blisk. Firstly the microstructure and mechanical properties of forged Ti-6Al-4V welded joints was focused on. Grains in the weld zone become coarse and large gradient organization structure appears in the heat affected zone (HAZ), which presents significant local heterogeneity. Microhardness of the weld zone is about 20% higher than that of the base metal. The size of different region of the welded joints was estimated. Then static tensile test of three different specimens were carried on. Experiment results show that the tensile and yield strength of welded joints are not less than that of the base metal. Finally the empirical relationship between strength and hardness of Ti-6Al-4V alloy is established. Tensile strength of the weld zone and the base metal were estimated. Compared to experiment data, the deviation is 3.56%, 0.097% respectively.

The aluminum depletion of NiCrAlY bond coat in an air-plasma-sprayed thermal barrier coating (TBC) has been studied by experimental and simulative approaches. Upon thermal exposure, Al depletion regions were observed. The depletion of aluminum is resulting from Al diffusion towards the surface of bond coat and into substrate. A mathematical model of Al depletion was presented. The model is able to explain the observed results in a qualitative way and has been shown that Al depletes within the bond coat by diffusion.

The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus help achieve future engine low emission, high efficiency and improve the reliability goals. Currently, there are two different processes such as the plasma spraying (PS) and the electron beam-physical vapor deposition (EB-PVD) techniques. The PS coating was selected to test the elastic modulus. Using the nanoindentation and resonant frequency method, the mechanical properties of ceramic top-coat were measured in-situ. According to the theory of the resonant frequency and composite beam, the testing system was set up including the hardware and software. The results show that the accurate characterization of the elastic properties of TBCs is important for stress-strain analysis and failure prediction. The TBCs systems are multi-layer material system. It is difficult to measure the elastic modulus of top-coat by tensile method. The testing data is scatter by nanoindentation method because of the microstructure of the ceramic top-coat. The elastic modulus of the top-coat between 20–1 150 °C is obtained. The elastic modulus is from 2 to 70 GPa at room temperature. The elastic modulus changes from 62.5 GPa to 18.6 GPa when the temperature increases from 20 °C to 1 150 °C.

In order to get thermal stress field of the hot section with thermal barrier coating (TBCs), the thermal conductivity and elastic modulus of top-coat are the physical key properties. The porosity of top-coat was tested and evaluated under different high temperatures. The relationship between the microstructure (porosity of top-coat) and properties of TBCs were analyzed to predict the thermal properties of ceramic top-coat, such as thermal conductivity and elastic modulus. The temperature and stress field of the vane with TBCs were simulated using two sets of thermal conductivity data and elastic modulus, which are from literatures and this work, respectively. The results show that the temperature and stress distributions change with thermal conductivity and elastic modulus. The differences of maximum temperatures and stress are 6.5% and 8.0%, respectively.

Turbine vanes and blades are the most intensively loaded elements in that they are subjected to a large variety of mechanical and high temperature loads. The thermal barrier coatings (TBCs) are widely used on different hot components of gas turbines, as blades and vanes, for both, power engineering as well as aeronautical applications. Currently, two methods are used for depositing TBCs on substrate, which are plasma spray (PS) and electron beam-physical vapor deposition (EB-PVD). A typical TBCs system consists of two thin coatings, including a ceramic coating and a metallic bond coat. Despite considerable efforts, the highly desirable prediction of their life time is still a demanding task. The PS coating was focused on in this work. Firstly, the TBCs systems are multiplayer material systems. The material properties are not easily determined, such as Young’s modulus of the top-coating of TBCs. Using the resonant frequency and the composite beam theory, the Young’s modulus of APS TBCs was gotten under from room temperature to 1150°C. Then using a commercial finite-element program, the model geometry is that of a cylinder specimen. The interface region between bond coat and top coating is modeled and meshed with a sinusoidal geometry. The temperature was designed and cycled over a range from room temperature to 1050°C. The force-air-cooling was designed to form temperature gradient across the thickness of TBCs. Finally, the fatigue life of TBCs was predicated. The maximum relative error is 20.1%.

Thermal barrier coating (TBC) is an essential requirement of a modern gas turbine engine. The TBC failure is the delamination and spallation. The oxidation damage under high temperature results in the reduction of interfacial adhesion. The interfacial fracture toughness is an important property to analyze the TBC failure. The interfacial fracture toughness of ceramic coating - bond coating has been researched in the past. However, the facture toughness of the bond coating - substrate due to the Al depletion was very few studied. In this study, a NiCrAlY bond coating by air plasma spray (APS) was deposited. The substrate was directionally solidified superalloy (DZ40M). Isothermal oxidation was performed at 10500 for 100h. Using the HXZ-1000 micro-hardness equipment, the five different times was chosen to test the hardness and the crack length, and then the fracture toughness was obtained. While the oxidation exposure time increased at 10500, the hardness of the substrate close to the bond coating decreased with the increase of the bond coating’ hardness. Meanwhile, the interfacial fracture toughness of the bond coating - substrate decreased because of the Al depletion.

Thermal barrier coatings (TBCs) have received increased attention for advanced gas turbine engine application. The oxidation damage plays an important role of the failure under high temperature load. An Y2O3 partially stabilized ZrO2 ceramic top coating was deposited a NiCrAlY bond coating by air plasma spray (APS). The substrate was directionally solidified superalloy (DZ40M). Isothermal oxidation has been performed at 700 and 1050 for 100h. The oxidation results in three transformations of the weight, the interface and the surface characters. All the specimens were characterized by highly precision balance, scanning electron microscopy (SEM) in cross-section, microscope with MFK2 visual measurement system on its surface. The curve of oxidation kinetics is obtained by weighting those specimens. The weight gain of the specimen under 700 is close to zero. Under 1050 the weight gain is very distinct. On the other hand, the interface cracks occur and extend at the interface between the ceramic and bond coating by SEM method. The thermal growth oxide (TGO) gradually appears on the coating surface under high temperature oxidation by MFK2. Last but not least, those observations will provide some ideas and damage parameters for the non-destructive inspection (NDI) for TBC under thermal load.

In gas turbines, thermal barrier coatings (TBCs) applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young's modulus and Poisson's ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAlY bond coat and Yttria stabilized zirconia (YSZ) top coat are deposited onto a nickel-base super alloy GH150 substrate. The Young's modulus and Poisson's ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young's modulus and Poisson ratio of other multilayer systems.

Based on the fatigue prediction model of exponential function and Whitney-Nuismer(WN) criterion of static strength for the composite material laminate with a circular hole, the stress correct factor (β) was put forward and a new fatigue prediction model for composite material laminate was set up. T300/KH304, which is recently studied and is a high capability composite material, was used as the raw material. In order to gain the factor β, the fatigue experiments of the laminates with holes in different diameters and the same ratio of width to diameter were conducted. The fatigue analysis and tests of the laminates with a hole 5 mm in diameter are carried out at different stress levels, and the results meet the engineering requirement. The simple, prompt and practical method is provided for the prediction of S-N curve of composite laminate with a circular hole.