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AbstractGear tooth spalling is a typical tooth surface defects in gear transmission. The accurate calculation of the time-varying mesh stiffness of the gear pair with spalling defect under mixed elastohydrodynamic lubrication (EHL) plays an important role in tooth damage prediction and fault feature analysis. In this work, an improved time-varying mesh stiffness (TVMS) model of spalling faulty gear in mixed EHL line contact considering the coupled effect of rough surface topography is established. The proposed model considers the combined effect of spalling defect, surface roughness topography, and lubrication on the contact characteristics of the meshing interface to obtain a revised contact stiffness, which is further used to determine the comprehensive TVMS. The cylindrical contact coefficient for curved meshing interface with spalling fault is derived and incorporated into the statistical micro-contact Greenwood and Williamson model (GW model) to obtain the asperity contact stiffness. The revised contact stiffness at the rough faulty gear interface is obtained from the parallel action of the asperity contact stiffness and oil film stiffness under load-sharing concept. The dynamic responses of the gear system are analyzed using the established mesh stiffness model through the six degrees of freedom translational-torsional dynamic model, in which the dynamic meshing force is calculated iteratively using the transit surface topography and geometrical parameters along the line of contact instead of a quasi-static meshing force. Effects of multi-parameters as surface roughness, spalling fault size, and lubricant on the mesh characteristics and dynamic responses of the gear system are further investigated and discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, we reported the in-situ preparation of manganese ferrite (MnFe 2 O 4) grafted polyaniline (Pani), a magnetic nanocomposite for the potential visible light photocatalytic material as well as electrode material for supercapacitor. The physical characterization of the prepared nanoparticle and nanocomposite was examined with various spectroscopic and microscopic analyses. The peaks observed in the X-ray diffraction study confirm the face-centered cubic phase of MnFe 2 O 4 nanoparticles with a grain size of ∼17.6 nm. The surface morphology analysis revealed the uniform distribution of spherical-like MnFe 2 O 4 nanoparticles on the surface of Pani. The degradation of malachite green (MG) dye under exposure to visible light was investigated using MnFe 2 O 4 /Pani nanocomposite as a photocatalyst. The results exposed the faster degradation of MG dye was accomplished by MnFe 2 O 4 /Pani nanocomposite than MnFe 2 O 4 nanoparticles. The energy storage performance of the MnFe 2 O 4 /Pani nanocomposite was analyzed through cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy analyses. The results exposed that the MnFe 2 O 4 /Pani electrode achieved a capacitance of 287.1 F/g than the MnFe 2 O 4 electrode (94.55 F/g). Further, the respectable capacitance of 96.92% was achieved even after 3000 repetitive cycles stability. Based on the outcomes, the MnFe 2 O 4 /Pani nanocomposite can be suggested as a promising material for both photocatalytic and supercapacitor applications. [ABSTRACT FROM AUTHOR]

The need for wireless condition monitoring and control of hydraulic systems in an autonomous and battery‐free manner is attracting increasing attention in an effort to provide improved sensing functionality, monitoring of system health, and to avoid catastrophic failures. The potential to harvest energy from hydraulic pressure ripples and noise is particularly attractive since they inherently have a high energy intensity, which is associated with the hydraulic mean pressure and flow rate. This paper presents a comprehensive overview of the state of the art in hydraulic pressure energy harvesting, which includes the fundamentals of pressure ripples in hydraulic systems, the choice of electroactive materials and device structures, and the influence of the fluid–mechanical interface. In addition, novel approaches for improving the harvested energy and potential applications for the technology are discussed, and future research directions are proposed and outlined. [ABSTRACT FROM AUTHOR]

• A twelve-DOF dynamic model of the gear-shaft-bearing-housing system with discontinuous contact interface is developed. • Dynamic responses of different transmitting components are analyzed for three different internal excitations. • An explicit mathematic model of transmission path function from internal vibration source to signal collecting point is constructed. • Transmission path function is verified by model predictions and experimental results. A twelve-DOF model of gear-shaft-bearing-housing system is developed to study the vibration transmission path characteristics under different internal excitations considering effect of discontinuous contact interfaces. Gear meshing generates vibrations to propagate through the transmission path consisting of gear, shaft, bearing, housing and multiple contact interfaces to reach the external transducer. Effect of contact interfaces between different transmitting components, including that between gear and shaft, inner race and outer race, outer race and housing are characterized using parallel contact stiffness and damping elements. Dynamic responses of transmitting components are analyzed for three internal excitations of single frequency sinusoidal force, dynamic meshing force of both normal and spalled gear tooth. An explicit mathematic model of transmission path function is constructed, which considers effect of transmission path on both amplitude attenuation and frequency structure shift for gear with/without fault. The transmission path function is verified with model predictions, finite element simulation and experiments. [ABSTRACT FROM AUTHOR]

• Ag single atoms (SAs) dispersed g-C 3 N 4 catalyst was prepared by a one-step photocatalytic immobilization strategy. • Rhodamine B as electron acceptor contributed to immobilize the Ag SAs and construct electron migration channels, endowing Ag SAs with more intrinsic activity. • The embedded Ag SAs provided electron transfer channels to achieve effective long-range charge separation and low bandgap. • Based on the synergistic effect between RhB and Ag SA/g-C 3 N 4 , Ag SA/g-C 3 N 4 exhibited enhanced photocatalytic performance for the degradation of organic pollutants in wastewater. Owing to their unique electronic structure, single atom (SA) catalysts exhibit high activity and selectivity in the photocatalytic elimination of organic compounds. Herein, to improve the intrinsic activity of Ag SAs, Ag SA/g-C 3 N 4 was synthesized via a one-step photocatalytic immobilization strategy. Ag SA/g-C 3 N 4 exhibited excellent photocatalytic performance in removing organic pollutants, achieving degradation efficiencies of 93.49% and 64.29% for rhodamine B (RhB) and tetracycline (TC), respectively, under visible-light irradiation for 180 min. This enhanced photocatalytic activity stemmed from the synergistic electronic interaction between Ag SA/g-C 3 N 4 and RhB, whose photocatalytic degradation contributed to immobilize the Ag SAs and construct electron migration channels. This electronic structure suppressed the aggregation of Ag SAs. Ag nanoparticles could retain a small particle size of 2.79 nm after being recycled thrice. This study provides an innovative method for the immobilization of Ag SAs to improve their photocatalytic activity in the removal of RhB and TC. [Display omitted] Ag SA/g-C 3 N 4 was prepared by one-step photocatalytic immobilization process with rhodamine B (RhB) as electron acceptor to help immobilize Ag SAs building interface electronic interaction, which endowed Ag SAs with more intrinsic activity. The novel electronic interaction between Ag SAs and g-C 3 N 4 facilitated strong light absorption. Ag SA/g-C 3 N 4 showed good photocatalytic activity for visible light degradation of RhB and tetracycline. [ABSTRACT FROM AUTHOR]

Nowadays, systematic research on the energy consumption of the belt drive mechanism is limited or rarely explored. Herein, we investigated the influence of a belt drive centrifugal fan’s pulley ratio, belt tension, and the number of belts on induction motor efficiency. As an experimental platform, a set of belts drive centrifugal fan was built, and a voltage phase control technology was proposed. The voltage phase angle of an induction motor was triggered, and the testing results were verified by driving a silicon-controlled rectifier (SCR) device. Experimental parameters such as centrifugal fan’s operating voltage, current, power, power factor, and shaft speed were analyzed, according to the centrifugal fan operating, matching different pulley ratios and belt tensions to control the induction motor’s load change. To maintain stable operation and to reduce energy consumption, the appropriate voltage phase angle is triggered without changing the centrifugal fan shaft speed. In addition, since the external installation is adopted, the overall system mechanism is not changed, and it can also be used as an alternative to a high-efficiency motor or a variable frequency drive (VFD). The output power can be appropriately changed according to the different pulley ratios. Excess power consumption can be reduced when the centrifugal fan is operating at a low load. When under heavy load, it can provide enough output power to keep the proper function of the centrifugal fan and thereby reduce the energy consumption. Under different motor load conditions, such as the change of the belt state, the energy consumption difference can be found and improved by appropriate voltage phase regulation. This is more favorable to subsequent centrifugal fan maintenance, and then adopts an appropriate energy-saving strategy for belt transmission machines with different pulley ratios in the industry. The power efficiency improvement plan of the belt drive machine was proposed and the goal of industrial upgrading was achieved. [ABSTRACT FROM AUTHOR]

Contact stiffness is an important parameter for describing the interface characteristics in many engineering applications. In this paper, five different statistical micro-models including the Greenwood-Williamson (GW), Zhao-Maietta-Chang (ZMC), Kogut-Etsion (KE), Jackson-Green (JG) and Brake are employed to predict the normal contact stiffness for rough surface contact. It is found that the expressions of contact stiffness obtained using the statistical micro-models are very complex and the direct relationship between the contact stiffness and normal load is not available. Accordingly, an explicit approximated expression for contact stiffness is established in terms of normal load based on the results of numerical simulations. The normal contact stiffness as a function of normal load can be approximated using a power law, in which the coefficient and power are related to surface roughness parameters, material properties as well as nominal contact area. The close agreement between the predicted results and full numerical simulations verify the accuracy of the established explicit expression. The contact stiffness calculated using the predictive expressions are also compared with available experimental results from both ultrasonic method and contact resonance method. Further, the explicit expression of contact resonance frequency for rough surface contact with respect to the normal load is also provided, which can be used to evaluate the contact resonance frequency. The predicted contact resonance frequency is also validated through comparing with experimental results. • Five different statistical micro-models are employed to predict the normal contact stiffness for rough surface contact. • Direct relationship between contact stiffness and normal load is not available using the statistical micro-models. • An explicit approximated expression for contact stiffness is established in terms of normal load. • Predictive contact stiffness values are verified using available experimental results. [ABSTRACT FROM AUTHOR]

Highlights • An improved RL iterative algorithm is proposed to measure inclusion size. • The spectral characteristics of transducer are considered to calculate the PSF. • The function to determine the final iteration number is established and calibrated. • The inclusion size measured from the restored C-scan images is more accurate. Abstract The accuracy of measuring inclusion size in direct C-scan image of immersion ultrasonic testing is restricted by the lateral resolution of the focused transducer, even if a high frequency is used, and the blurred edge due to scattering of sound waves at inclusions. In this work, an improved image restoration method that is based on the Richardson-Lucy (RL) iterative algorithm is proposed, which is used to restore the C-scan image and improve the accuracy of inclusion size measurement in immersion ultrasonic testing. For the improved RL iterative algorithm, the point spread function (PSF) is derived based on the multi-Gaussian beam model and Kirchhoff approximation, which considers the propagation properties of sound waves at water-steel interface and the spectral characteristics of the transducer with high frequency. In order to determine the final iteration number, the relationship between final iteration number and size of the inclusion in the image is established by restoring the simulated C-scan image and further calibrated with size correction factor. The size correction factor considers the effect of sound attenuation and electro-mechanical transformation encountered in practical testing equipment. Experimental results show that the inclusion sizes measured in restored C-scan images agree well with the optical micrograph results, which prove the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract In this work, an improved acoustic model based on virtual material is proposed to provide an accurate measurement of interfacial contact stiffness using ultrasound. The rough interface is assumed to be a thin layer of virtual material to incorporate the effect of ultrasound attenuation at the interface. The derived acoustic model shows that the developed contact stiffness expression is a refinement of the general spring model by considering the interfacial property and is related to the material properties of the virtual material thin layer. The analytical solutions of the material parameters for the virtual material are further deduced based on the statistical micro-contact theory. It reveals that the surface roughness parameters of the contact interface and the material property of the contact body are other information required to improve the measurement accuracy of contact stiffness, in addition to the ultrasonic measurement parameters in the original spring model. The accuracy of the developed acoustic model for contact stiffness measurement is verified by comparison with the spring model and the statistical contact models. [ABSTRACT FROM AUTHOR]

In this work, an eight-degree-of-freedom (DOF) dynamic model of the gear-shaft-bearing-housing system is established and the vertical vibration transmission and energy dissipation characteristics through the multiple transmitting interfaces under the impulse force due to gear fault are studied. The elastic deformations at the interfaces between gear and shaft, inner race and outer race, outer race and housing are formulated by the corresponding contact stiffness. The housing compliance is also included. A half-sine impulse force with two characteristic parameters as amplitude and time duration, which are associated with the defect type and size, is employed to represent the effect of gear fault on the system dynamics. The acceleration responses for different transmitting components as gear, inner race, outer race and housing are calculated for different impulse time duration, different impulse force amplitudes and shaft rotating speeds. The vibration transmission and energy dissipation through the multiple interfaces are characterized by the defined vibration transmission ratio and energy dissipation ratio. Obvious attenuation in acceleration magnitude is observed between the transmitting components from gear to housing. The maximum attenuation occurs at the transmission from inner race to outer race, while the minimum is between the outer race and the housing. The time duration of the impulse force determines the resonance and also the vibration transmission characteristics of the system. The energy dissipation increases nonlinearly with the amplitude of the applied impulse force. Results also suggest that the interface between inner race and outer race, and the interface between gear and shaft dissipated about 60% and 40% of the total energy, are the main sources of energy dissipation in the system. However, the shaft rotating speed has limited effect on the vertical impulse vibration amplitude, vibration transmission and energy dissipation. Experimental validation is performed, which supports the characteristics obtained from numerical results. [ABSTRACT FROM AUTHOR]

The surface topography of engineering rough surfaces has an enormous influence on contact mechanics of the interface and further the dynamics of the contact system. In this paper, the force-deflection characteristic and the nonlinear vibration of a rough surface interacting with a rigid flat surface are studied. A three-dimensional rough surface is constructed using a modified two-variable Weierstrass–Mandelbrot fractal function and the force-deflection is determined to be a positive power-law function. The power has the values larger than unity and increases with a rougher surface topography. Approximation of the force-deflection characteristic is also presented. Accordingly, the natural frequency is determined both exactly and approximately from the numerical calculation of the natural period and using the multiple scales method on the approximate equation, respectively. The primary resonance responses under harmonic excitation are also determined as well as the jump-up and jump-down responses. The nonlinear contact stiffness characteristics and the effect on natural frequency and the frequency responses are illustrated for different rough surface topographies. It is shown that the variation of natural frequency with amplitude and the multi-valued region of frequency responses increase with a rougher surface topography; however, the jump-up and jump-down frequencies both decrease, as well as the peak amplitude. [ABSTRACT FROM AUTHOR]

The nonlinear oscillatory motion of an elastic sphere in contact with a rigid flat surface to different loads is clearly dominated by the damping mechanism of the system. However, the damping power law is unable to be identified using the decrement method due to the almost identical free vibration responses. In this paper, a procedure which allows identification of the nonlinear viscous damping from the free response data is presented. The procedure is based on the figure relating the damping restoring force and the velocity which is distinguishable for different damping laws. A dynamic experiment is described, and from the free vibration data obtained the damping restoring forces are extracted for spheres with different materials being steel and low density polyethylene (LDPE). Subsequently, based on the models and observations the characteristics of the damping law are estimated. The results show that a linear viscous damping model is a good representation for the steel sphere contact, which confirms earlier studies; whilst the LDPE sphere contact follows a nonlinear power law for the viscous damping function, which is newly obtained. The validity and accuracy of the proposed method are supported by the good agreement between numerical results and experimental results. [ABSTRACT FROM PUBLISHER]

Device architectures, electroactive materials, energy harvesting, hydraulic pressure ripples Hydraulic Pressure Ripple Energy Harvesting: Structures, Materials, and Applications (Adv. Keywords: device architectures; electroactive materials; energy harvesting; hydraulic pressure ripples EN device architectures electroactive materials energy harvesting hydraulic pressure ripples 1 1 1 03/06/22 20220303 NES 220303 B Hydraulic Pressure Energy b In article number 2103185, Chris R. Bowen and co-workers present a comprehensive overview of the state-of-the-art in hydraulic pressure energy harvesting, which includes the fundamentals of pressure ripples in hydraulic systems, and the selection of electroactive materials and device structures. [Extracted from the article]

Abstract: In this paper, the energy dissipation in a mechanical lap joint is studied using the one-dimensional microslip friction model by incorporating the effect of interface tangential contact stiffness. A non-uniform pressure distribution of exponent law at the interface is considered and the resulted distinct stick-slip transitions along the contact interface are presented. Expressions of the critical slip loads giving rise to stick-slip transitions along the contact interface are determined. The loading force–displacement curves for different pressure distribution laws and different interface tangential stiffness are obtained and compared with each other. The hysteresis curves of the oscillating tangential contact forces versus tangential displacements and the dissipated energy at the contact are determined. It is shown that a classical power-law behavior is predicted between the energy dissipation and the applied tangential force. However, the exponents of the power-law are not the theoretical cubic but vary with interface stiffness and pressure distributions. The obtained results suggest that the joint interface tangential stiffness and interfacial pressure distribution are reasons for the varying exponent values obtained in experimental work. [Copyright &y& Elsevier]

Abstract: Three methods are used to determine the natural frequency of undamped free vibration of a mass interacting with a Hertzian contact stiffness. The exact value is determined using the first integral of motion. The harmonic balance method is used on a transformed equation for an approximate solution, and the multiple scales method is used on an approximate equation. The maximum initial displacement avoiding contact loss is also determined, and the corresponding exact natural frequency is also obtained analytically. The methods are evaluated by studying the free vibration of an elastic sphere on a flat rigid surface. [Copyright &y& Elsevier]

Summary We have assessed the kinetics of host gene expression in granulomas of mice infected with virulent Mycobacterium tuberculosis , using an approach that incorporates the laser capture microdissection (LCM) and real-time PCR technology in conjunction with a newly derived mathematical equation. The results have provided evidence indicating that conventional use of whole infected lungs to study granuloma-specific gene expression can yield data that may not genuinely reflect intralesional events. Significantly, the expression of nine host genes known to regulate the inflammatory response to M. tuberculosis , as determined by real-time PCR analysis of microdissected granuloma-derived cDNAs, was downregulated (up to 27-fold) at around the time when the rapid growth phase of the bacilli in the lungs of infected mice ends. This downregulation was masked when whole infected lungs were used for the studies. The data suggest that the host immune system can adjust and respond to, or can be modulated by specific physiological states of the tubercle bacillus in vivo . The LCM/real-time PCR-based system described in this study can be applied to safely and accurately evaluate gene expression in any lesions that can be microscopically visualized, including those contained in biohazardous tissues. [ABSTRACT FROM AUTHOR]

• Generalized model for harvesting pressure ripples using the piezoelectric effect is developed. • Force-deflection relationship of the system is determined as a Duffing hardening response. • Expressions for input energy, output electrical energy and energy efficiency are developed. • Good agreement observed between model and experiment for output voltage and power. There is an increasing desire to monitor and control hydraulic systems in an autonomous and battery-free manner. One solution to this challenge is to harvest hydraulic pressure ripples and noise by exploiting the piezoelectric effect. This paper develops a new generalized model of a hydraulic piezoelectric harvester based on a circular edge-clamped flat plate interface with a central piezoelectric stack. Such a model allows the relationships between harvesting performance and structure to be assessed in detail. It is demonstrated that the force-deflection relationship of a circular edge-clamped plate with a central lumped mass follows a cubic hardening Duffing equation. A single degree of freedom (SDOF) lumped-parameter model of the system is established where the nonlinear frequency response resulting from hardening nonlinearities are explored. The input mechanical energy and the output electrical energy both exhibit a quadratic nonlinear relationship with vibration amplitude. The maximum output occurs at the jump-down frequency and the overall energy conversion efficiency of the system is determined. The optimum resistance load for maximum output energy and energy efficiency are obtained as non-dimensional excitation frequency. Experimental validation is performed and good agreement is observed between model results and experimental measurements. The developed model provides important insights into the optimization of power output and response of future hydraulic energy harvesting devices. [ABSTRACT FROM AUTHOR]

With a combination of the improved ultrasonic measurement model (IUMM) and support vector machines (SVM), a novel method to identify inclusions and cavities in metallic materials using scanning acoustic microscopy is proposed. In the IUMM, a hybrid model of Born approximation and Kirchhoff approximation is developed to calculate the far-field scattering amplitude of cavities, which improves the accuracy in phase and amplitude of the predicted pulse-echo signals of defects. The SVM classifier, with the amplitude and peak frequency of the predicted echo signals as major features, is applied to distinguish inclusions and cavities. The experimental result shows that the echo signals predicted by the proposed IUMM are more accurate than conventional UMM in amplitude and frequency. The SVM classifier, with the predicted signals as the training set, enables the identification of inclusions and cavities in metallic materials successfully. This work improves the performance of SAM in the identification of internal defects in metallic materials and realizes the intelligent analysis of ultrasonic signals. [ABSTRACT FROM AUTHOR]

• An analytical model is developed to evaluate the interfacial stiffness ratio theoretically considering the interface as an equivalent thin layer. • Effective moduli of the thin layer are derived by a homogenization process of the deformed asperities over the whole rough surface. • The interfacial stiffness ratio depends on surface topographies, interfacial separations, and material properties of contacting bodies. • The interfacial stiffness ratios predicted by the proposed model are basically consistent with experimental results. This work presents a semi-analytical model to evaluate the interfacial stiffness ratio of stationary contacts between rough surfaces. The rough contact interface is described as a homogenized thin layer with effective moduli, which are employed to characterize the ratio of the tangential to normal contact stiffness. In conjunction with the micro-contact analysis of the deformed asperity, effective moduli of the homogenized layer are determined by an ensemble average process of the moduli produced by deformed asperities made over the rough interface. Results show that the sought ratio is related to the surface topography, interfacial separation, and material properties of contacting bodies. Variations of the interfacial stiffness ratio with the applied load for different surface topographies are presented. The proposed model of the stiffness ratio is verified by comparing with the previous models and experimental results eventually. [ABSTRACT FROM AUTHOR]

In this work, the normal contact stiffness of lubricated rough interface is evaluated theoretically by describing the lubricated rough interface as an equivalent thin layer. Layer parameters, including equivalent thickness and effective Young's modulus, are used to characterize the normal contact stiffness by incorporating the contributions of asperity contact and lubricant contact simultaneously. On the basis of layer parameters, the normal contact stiffness of lubricated rough interface is obtained as a function of interfacial separation, surface topography, and properties of contacting solids and lubricants. Effects of surface topographies and lubricant types on the normal contact stiffness are investigated at varying interfacial separations and contact area fractions. The proportion of solid stiffness and lubricant stiffness from the total normal stiffness is also discussed. Numerical solutions reveal that the normal contact stiffness depends sensitively on the lubricant property at initial contact, whereas the influences of surface topographies become obvious with the decrement of interfacial separation or increment of contact area fraction. Comparisons between the predicted values of normal contact stiffness and experimental data for both dry interface and lubricated interface are presented to validate the rationality of the developed model. [ABSTRACT FROM AUTHOR]

• A new dynamic evolutionary digital filter method is proposed to realize SNR improvement of early fault. • Cloning and mating evolutionary strategies in Dyna-EDF method is dynamically adjusted according to the iterative process. • The proposed method achieves better denoising performance than traditional EDF methods and the classic denoising methods. Signal denoising is one of the most essential steps in mechanical fault diagnosis, which can help improve the signal-to-noise ratio (SNR) and find faults as earlier as possible. Many denoising techniques have been developed to suppress both Gaussian white and non-Gaussian background noise. However, most of them achieved poor performance in terms of assessing local gear fault in the early stage. The key problem is that only one or several gear tooth's stiffness or displacement excitation are aroused in the beginning of local faults and most of the gear teeth or gear pairs are healthy, especially for the multi-stage gearbox. And both the normal gear meshing signals and background noise lead to low SNR of fault characteristics. To overcome this problem, this paper proposes a dynamic evolutionary digital filter (Dyna-EDF) method to realize the optimal suppression of background noise and normal gear meshing component in the acquired signal aiming to enhance the SNR of early fault characteristics. The proposed method belongs to an adaptive noise cancellation (ANC) method, which can find and suppress the relevant component between the acquired signal and reference signal based on an iterative optimization of a digital filter. In the proposed method, a filter parameter population and ANC structure is initialized and established firstly. Then the filter parameters of the population are dynamically adjusted to find the optimal filter based on cloning and mating evolutionary strategies. Furthermore, "survival of the fittest" idea is employed for the optimal filter searching and applied during each iteration in Dyna-EDF method to prevent the premature problem that found in traditional EDF. Finally, the derived optimal filter is applied to suppress the relevant component between the acquired signal and reference signal using an ANC process. Results show that the proposed Dyna-EDF method successfully increase the SNR of fault characteristics, both normal gear mesh component and background noise are suppressed effectively. The proposed Dyna-EDF method seems achieve better denoising performance than traditional EDF method, its improved versions and the traditional denoising methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • The membranes were fabricated by filtering g-C 3 N 4 nanosheets and CTS onto HPAN. • The membranes demonstrated selective separation of monovalent and divalent ions. • The membranes exhibited high water permeability at low pressure. • The diffusion behaviors of water and ions through g-C 3 N 4 membranes was studied by MD simulations. The complex transport mechanism of water and ions in the membrane hinders the design of free standing membranes. The mechanism of the mass transport characteristics of traditional nanofiltration membranes is no longer applicable to free standing membranes due to the change of the driving force in the membrane. In this study, the vacuum filtration of the g-C 3 N 4 suspension was simulated to form a free standing membrane model for the first time by using the molecular dynamics (MD) simulations. In the nanochannels formed by the g-C 3 N 4 nanosheets, the water molecules rapidly penetrated across the free standing membrane due to ultra-low friction. On the other hand, the hydrated Na+ and Mg2+ ions needed energy to partially dehydrate and penetrate across the free standing membrane. Moreover, the MD simulations indicated that the speed of Mg2+ ions penetrating across the g-C 3 N 4 nanochannels was lower than that of Na+ ions. Combined with the computational works, salt retention experiments were conducted to demonstrate the correctness of the proposed model. Further, the developed membranes exhibited excellent non-swelling stability and antibacterial activity in aqueous solutions. The g-C 3 N 4 free standing membranes prepared in this study can effectively realize the separation of monovalent and divalent ions, accompanied with high permeability. [ABSTRACT FROM AUTHOR]

Background: The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) are the most commonly used scales to detect mild cognitive impairment (MCI) in population-based epidemiologic studies. However, their comparison on which is best suited to assess cognition is scarce in samples from multiple regions of China. Methods: We conducted a cross-sectional analysis of 4923 adults aged ≥55 years from the Community-based Cohort Study on Nervous System Diseases. Objective cognition was assessed by Chinese versions of MMSE and MoCA, and total score and subscores of cognitive domains were calculated for each. Education-specific cutoffs of total score were used to diagnose MCI. Demographic and health-related characteristics were collected by questionnaires. Correlation and agreement for MCI between MMSE and MoCA were analyzed; group differences in cognition were evaluated; and multiple logistic regression model was used to clarify risk factors for MCI. Results: The overall MCI prevalence was 28.6% for MMSE and 36.2% for MoCA. MMSE had good correlation with MoCA (Spearman correlation coefficient = 0.8374, p < 0.0001) and moderate agreement for detecting MCI with Kappa value of 0.5973 (p < 0.0001). Ceiling effect for MCI was less frequent using MoCA versus MMSE according to the distribution of total score. Percentage of relative standard deviation, the measure of inter-individual variance, for MoCA (26.9%) was greater than for MMSE (19.0%) overall (p < 0.0001). Increasing age (MMSE: OR = 2.073 for ≥75 years; MoCA: OR = 1.869 for≥75 years), female (OR = 1.280 for MMSE; OR = 1.163 for MoCA), living in county town (OR = 1.386 and 1.862 for MMSE and MoCA, respectively) or village (OR = 2.579 and 2.721 for MMSE and MoCA, respectively), smoking (OR = 1.373 and 1.288 for MMSE and MoCA, respectively), hypertension (MMSE: OR = 1.278; MoCA: OR = 1.208) and depression (MMSE: OR = 1.465; MoCA: OR = 1.350) were independently associated with greater likelihood of MCI compared to corresponding reference group in both scales (all p < 0.05). Conclusions: MoCA is a better measure of cognitive function due to lack of ceiling effect and with good detection of cognitive heterogeneity. MCI prevalence is higher using MoCA compared to MMSE. Both tools identify concordantly modifiable factors for MCI, which provide important evidence for establishing intervention measures. [ABSTRACT FROM AUTHOR]

• This two-step precise targeting nanoplatform could realize the site-specific release of different drugs. • Apoptosis was caused by utilizing the organelle's own characteristics. • Two drugs with different mechanisms achieve the purpose of synergistic anti-tumor. With the in-depth research of organelles, the microenvironment characteristics of their own, such as the acid environment of lysosomes and the high temperature environment of mitochondria, could be used as a natural and powerful condition for tumor therapy. Based on this, we constructed a two-step precise targeting nanoplatform which can realize the drug release and drug action triggered by the microenvironment of lysosomes (endosomes) and mitochondria, respectively. To begin with, the mesoporous silica nanoparticles (MSNs) were modified with triphenylphosphonium (TPP) and loaded with 2,2′-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH). Then, folic acid (FA) targeted pH-sensitive liposomes containing docetaxel (Lipo/DTX-FA) were prepared by thin-film dispersion method, and the core-shell AIPH/MSN-TPP@Lipo/DTX-FA nanoparticles were constructed by self-assembly during the hydration of the liposomes. When this nanoplatform entered into the tumor cells through FA receptor-mediated endocytosis, the pH-sensitive liposomes were destabilized in the lysosomes, resulting in the release of DTX and AIPH/MSN-TPP nanoparticles. After that, AIPH was delivered to mitochondria by AIPH/MSN-TPP, and the alkyl radicals produced by AIPH under the high temperature environment can cause oxidative damage to mitochondria. Not only that, the DTX could enhance the anti-tumor effect of AIPH by downregulating the expression of anti-apoptotic Bcl-2 protein. The in vitro and in vivo results demonstrate that this delivery system could induce apoptosis based on organelles' s own microenvironment, which provides a new approach for tumor therapy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the contact models for contact and vibration features of cylindrical roller bearings (CRBs). CRBs are important parts of rotating machinery. The contact deformation between the roller and the raceway is an essential research topic for the CRBs. The contact deformation between the roller and the raceway can greatly affect vibration characteristics and fatigue life of the CRBs. In this investigation, six different methods are adopted to calculate the contact deformation, contact area width and contact stress between the roller and raceways of a CRB. Design/methodology/approach: In this paper, the contact deformations and the contact stiffnesses between the roller and the raceway of a CRB obtained by various well-known empirical methods (Lundberg's, Palmgren's, Houpert's, Cheng's and Hertzian methods) are directly compared with those by the finite element (FE) method. A two degree-of-freedom (2 DOF) dynamic model of the CRB is applied to investigate the effects of the contact stiffness obtained by different line contact deformation calculation methods on the vibration characteristics, such as the root mean square (RMS), the peak to peak (PTP), the crest factor and the kurtosis of the displacement, velocity and acceleration of the inner raceway. Findings: The computational results show that different calculation methods for the contact deformations between rollers and raceways have significant effects on the vibrations of the CRB. It is found that that the differences of computational results obtained by Palmgren's and Lundberg's models with respect to the FE method are smaller than those by the other three methods, i.e. Houpert's, Cheng's and Hertzain models. The amplitude and peak frequency of the frequency response functions from Palmgren's method are much more similar to those from the finite element method. The above results indicate that Palmgren's method is a better calculation method for predicting the contact deformations and dynamics of the CRBs. Originality/value: This work adopts six different methods to calculate the contact deformation, contact area width and contact stress between the roller and raceways of a CRB. Moreover, a vibration model of a CRB is used to investigate the effect of contact stiffness obtained by the above methods on the vibrations of the CRB. The works can give some guidance for the accurate analytical method for calculating the contact deformations between rollers and raceways and the vibrations of the CRB. [ABSTRACT FROM AUTHOR]

Highlights • A new adaptive evolutionary digital filter is proposed for gear fault detection. • The speed and noise cancellation performance of the proposed method are validated. • The proposed method exhibits much faster convergence rate than other methods. Abstract Evolutionary digital filter (EDF) is an adaptive filter that controlled by adaptive algorithm based on the evolutionary strategies: cloning and mating. The adaptive algorithm of EDF exhibits the advantage of avoiding local optimum problems that arise from a multiple-peak performance surface of an adaptive noise cancellation (ANC) system. However, the convergence rate of the classic EDF is limited by inappropriate arrangement of evolutionary strategies and large population of individuals. In this paper, a new method referred to alternately evolutionary digital filter (AEDF) is proposed in order to solve the problem of lower convergence rate of the classic EDF. The basic concept of the proposed method is to alternately apply mating evolutionary strategy to locate the peaks in performance surface quickly and then apply cloning evolutionary strategy to get the global optimum near the peaks accurately. The convergence rate and noise cancellation performance of the proposed method is verified by both simulated signals and experimental signals. The results show that the proposed AEDF-based ANC method can effectively detect the gear tooth spalling faults in noisy environment and exhibits much faster convergence rate compared to previous methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • pH-response attapulgite (p-ATP) nanofibers were prepared by surface grafting. • The compatibility between PVDF and t-ATP resulted in excellent tensile strength. • Anti-fouling performance of membrane increased due to the hydrophilic p-ATP. • Adsorption and desorption of H 2 O from p-ATP occurred with the change in pH. • The membrane is easy-cleaning due to the pH-response property of p-ATP. Membrane separation is an efficient strategy to disrupt the spread of pathogens in an aqueous solution and produce clean water, but its performance is seriously affected by fouling caused by bioadhesive. In this study, novel pH-response attapulgite (p-ATP) nanofibers were prepared and applied in the modification of poly(vinylidene fluoride) (PVDF) ultrafiltration membrane for bovine serum albumin (BSA) solution purification. Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) was grafted onto the surface of attapulgite (ATP) to offer pH-response property and to improve compatibility with PVDF. p-ATP is a hydrophilic material, which can increase the anti-biofouling performance of PVDF, and its one-dimensional structure is beneficial for enhancing the inter-entanglement with organic chains in the membrane matrix. The resultant composite membrane loaded with 7% p-ATP presented 77.2% and 108.1% increase in stationary permeance and mechanical strength, respectively, than that of the pristine PVDF membrane. Furthermore, the PDMAEMA chains in p-ATP will be shrunken or swollen with the change of pH value, resulting in adsorbing or releasing water molecules. This process is effective to mitigate the adhesion between biofoulants and membrane and can break the already formed biofouling layer. So, the composite membranes are easily to be cleaned via a simple pH-change cleaning process. The molecular dynamic simulation was also conducted to analyze the high performance of the PVDF/p-ATP membrane to provide theoretical support. [ABSTRACT FROM AUTHOR]