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This paper investigates the nonlinear free vibration of spinning pre-twisted functionally graded material (FGM) plates in thermal environment. Based on the Kirchhoff plate theory and von Kármán large-deformation theory, the nonlinear dynamic model is established via the Lagrange equation, where the warping effect is taken into account. The material properties are related to temperature and change according to a power-law exponent distribution. The theoretical solution of nonlinear-free vibration is obtained using the multiple scale method. The effects of power-law exponent, temperature difference, spinning speed, hub radius ratio, and twist angle on nonlinear-free vibration characteristics of the spinning pre-twisted cantilever FGM plates are discussed. The results show that the spinning pre-twisted cantilever FGM plate exhibits nonlinear hardening-spring vibration behavior, while the characteristics weaken with the increase of spinning speed. The twist angle and setting angle have coupling effects on the nonlinear vibration characteristics of spinning pre-twisted FGM plates. [ABSTRACT FROM AUTHOR]

Oxyntic gland neoplasm (OGN) is a rare subtype of gastric cancer. The aim of this study is to evaluate the prevalence, clinicopathological features, effectiveness and safety of endoscopic treatment, as well as the prognosis of OGN. We retrospectively analyzed the data of patients pathologically diagnosed with OGN at our hospital from November 1, 2019 to May 1, 2023. A total of 36 patients with 45 lesions were identified, resulting in a disease frequency of 0.047% (36/76,832). The mean age was 55.0 ± 7.5 years, with a male-to-female ratio of about 1:1.12. Most lesions were ≤10 mm in size (84.4%), located in the upper third of the stomach (73.3%), exhibited slight elevation (75.5%), appeared whitish (55%), had dilated blood vessels on the surface (75.5%). 16 and 21 lesions were treated by precutting endoscopic mucosal resection (EMR-P) and endoscopic submucosal dissection (ESD), respectively. No significant differences were found between EMR-P and ESD in terms of en bloc resection rate (100% vs 100%, p = 1.000), complete resection rate (100% vs 90.5%, p = 0.495), and curative resection rate (93.8% vs 90.5%, p = 1.000). No complications such as bleeding and perforation were observed. No recurrence or metastasis was observed during the follow-up period. OGN is a rare tumor with unique clinical, endoscopic, and pathological characteristics. EMR-P and ESD are deemed safe and effective for treating OGNs. The relatively faster and easier EMR-P seems at least non-inferior to ESD, especially for removal of smaller OGNs. The overall prognosis is favorable. [ABSTRACT FROM AUTHOR]

The thorax is the central component of the insect flight drivetrain, making it essential to understand how thoracic muscles influence insect flight for flapping wing microair vehicle design. This paper presents a theoretical model that takes into account the influence of thoracic muscles on flapping wing motion with reference to real insects. The thoracic muscle effect is simulated by the chordwise torsional spring, whose stiffness is derived from a comparison test with the results of real insect experiments. The elastic deformation of the flexible flapping wing is modeled by the von Kármán nonlinear plate theory. The predictive quasi-steady aerodynamic model based on the blade element theory can estimate the aerodynamic force, and the modeling of the spanwise bending and twisting is done with quadratic polynomials. The equations of motion are solved using the Newmark-Raphson method. Results suggest that including the influence of thoracic muscles decreases cycle-averaged lift and power, but enhances the efficiency of lift production by 23%. Moreover, it also postpones pitching motion and reduces its amplitude, though the movement trends of the flapping motion remain approximately unchanged regardless of the inclusion of the thoracic muscle effect. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the precise relationship between the Hausdorff dimension of possible singular point set S of suitable weak solutions and the parameter α in the nonlinear term in the following parabolic equation h t + h x x x x + ∂ x x | h x | α = f. It is shown that when 5 / 3 ≤ α < 7 / 3 , the 3 α − 5 α − 1 dimensional parabolic Hausdorff measure of S is zero, which generalizes the recent corresponding work of Ozánski and Robinson in [SIAM J. Math. Anal., 51, 228–255 (2019)] for α = 2 and f = 0. The same result is valid for a 3D modified Navier–Stokes system. [ABSTRACT FROM AUTHOR]

The thickness configuration effect on natural frequency and critical speed of spinning variable-thickness cylindrical shells is investigated in this paper. Based on Love's thin shell theory, the eigenfrequency equation is derived by employing the Rayleigh–Ritz method in conjunction with Chebyshev polynomials, considering the effects of Coriolis and centrifugal forces due to rotation. Seven types of thickness configurations and various classical boundary conditions are taken into account. Backward and forward wave frequencies, the critical speed, and the mode shapes of the spinning variable-thickness cylindrical shells are solved. Results show that the thickness configuration not only changes circumferential wave number corresponding to the lowest natural frequency, but also affects the critical speed. However, the influence of thickness configuration on mode shapes of the shell is not obvious. The stronger the boundary constraints, the more obvious effect of slope of thickness variation on the critical speed of spinning cylindrical shells. [ABSTRACT FROM AUTHOR]

The aerodynamic characteristics of flapping rotary wings (FRWs) have received considerable attention in design. In this study, optimizations of aerodynamic performance and kinematics of FRWs over the parameter space are explored. A well-validated Quasi-Steady model is employed to estimate the aerodynamic characteristics of FRWs in hovering flight, and a genetic algorithm is utilized for optimizing. It is assumed that flapping and pitching motion are given by motion parameters actively, while rotation is produced passively. Our results show that the optimal kinematic parameters are independent of flapping frequencies. The maximum lift comes from the high rotational speed caused by the small pitching amplitude, and the maximum power factor is from the large pitching amplitude. The dimensionless optimization of the flapping velocity as reference velocity is comparable to the dimensional results. The optimization model proposed in this study can be applied to the actual model for qualitative analysis. Rotational equilibrium power factor can reach more than 80% of the maximum value without rotation equilibrium constraint, but which rotational status can achieve the maximum power factor depends on the pitching angle at the mid-downstroke (αd). This study is helpful for the kinematic parameter design and further research of FRWs. [ABSTRACT FROM AUTHOR]

• An effective theoretical dynamics model of BFJDSs is proposed. • Vibration experiment of BFJDSs is conducted. • Experiment validates the present theoretical model. • Present model is applicable for bolt looseness and no-looseness conditions. Bolted flange joint disk-drum structures (BFJDSs) are key components in aero-engines, in which fatigue damage often occurs due to structural vibration. However, no study has so far given an effective theoretical dynamic model of BFJDSs. In this study, an effective dynamic model of BFJDSs is proposed. The present model considers the flange effect, non-uniform contact pressure of bolted joint, and bolt mass. The theoretical expression for describing the stiffness variation of bolted joints is presented. During the modeling process, the energy functions of disk, drum, and flange are obtained according to the Kirchhoff plate, Sanders' shell, and Euler-Bernoulli beam theories, respectively. The non-uniform artificial spring technique is adopted to simulate the pressure distribution of bolted joint. This method is capable of taking into account the contact pressure, which is closer to real contact situation. The displacement functions of disk and drum are expanded by using the Chebyshev orthogonal polynomials, and the motion equations are obtained by employing the Lagrange equation. Then, the experimental studies are performed on BFJDSs to illustrate the effectiveness of the theoretical model. Finally, the frequency veering and coupling vibration phenomena are revealed. The comparison studies indicate that the established theoretical model can well predict the vibration characteristics of BFJDSs under both bolt looseness and no-looseness conditions. The maximum error can be reduced from 46.81% to 3.61% by using the present dynamic model. [Display omitted] [ABSTRACT FROM AUTHOR]

The vibration characteristics of a rigid-flexible coupling spacecraft with double-direction hinged solar arrays are studied. The Kirchhoff plate theory is adopted to derive the governing equations. The Chebyshev polynomials are introduced as admissible functions to construct the dynamic model of each solar panel. The Lagrange multiplier method is employed to describe the continuity conditions of the flexible hinges. The Rayleigh-Ritz method is used to obtain the natural frequencies and rigid-flexible coupling global mode shapes. The validity of the present method is verified by comparing with the ANSYS results. Then, detailed studies are carried out to illustrate the effects of the inertia moment of the central rigid body, hinges stiffness, and aspect ratio of solar panels on the natural frequencies and mode shapes of the spacecraft. The results demonstrate that there exist a series of frequency veering and mode shift phenomena due to the variation of inertia moment, hinges stiffness, and aspect ratio. The inertia moment of the central rigid body plays a significant role in the attitude motion of the central rigid body. Finally, the mode localization factor is introduced to compare the mode localization degrees of three types of spacecraft. Results reveal that the longer the length of chord-wise direction solar panels, the more severe mode localization degree. • The dynamical model of rigid-flexible coupling spacecraft with double-direction hinged solar arrays is established. • Improved continuity conditions for the flexible hinges are proposed. • Effect of inertia moment of central rigid body is revealed. • The mode localization, frequency veering, and mode shift phenomena are discovered. [ABSTRACT FROM AUTHOR]

C20H22Cu3N8O10, monoclinic, C2/c (no. 15), a = 12.0766(11) Å, b = 16.2778(14) Å, c = 14.7605(13) Å, β = 97.8580(10)∘, V = 2874.4(4) Å3, Z = 4, Rgt(F) = 0.0420, wRref (F2) = 0.0988, T = 298.15 K. [ABSTRACT FROM AUTHOR]

Bolt connection is commonly used to assemble shell structures in engineering fields. Prolonged external excitation can induce stick, slip, even separation states at the connection interface, leading to complex nonlinear dynamics in bolted shell structures. Understanding the dynamic mechanism of bolted joined shells under stick–slip-separation condition is crucial for the design and application of these structures. In this study, we aim to build the nonlinear dynamic model and reveal the vibration mechanism of bolted joined conical-cylindrical shells with stick–slip-separation behavior. During the development of the mechanical model of the bolt connection, the axial bilinear stiffness characteristics and interface friction behaviors are taken into account simultaneously, which could simulate the transition of the contact state at the connection interface. The rigid joint between the conical and cylindrical shells is realized via successive distributed artificial springs. Donnell's shell theory as well as the displacement assumption of Chebyshev polynomials are employed in theoretical modeling, and the governing equation is obtained by the Lagrange equation. In contrast with existing research and experimental data, the accuracy of the present theoretical model is validated. Both theoretical and experimental results indicate the frequency multiplication and dynamic softening phenomena as the excitation level increases. By the consideration of the stick-slip-separation behavior at the connection interface in the modeling, these nonlinear vibration behaviors can be effectively illustrated. Additionally, hysteresis characteristics are further investigated to explore frictional energy dissipation. The stick–slip-separation contact state at the connection interface under different excitation levels, bolt preloads and cone angles are also analyzed. The present investigation provides a basis for the design and health condition monitoring of bolted shell structures. [ABSTRACT FROM AUTHOR]

• Dynamic model of shaft-disk rotors in axial non-uniform temperature field is developed. • Three-dimensional displacement fields for both shaft and disk are considered. • Temperature-dependent material properties are considered. • Present model can effectively predict vibrations of shaft-disk rotors in axial non-uniform temperature field. • Effect of non-uniform temperature field is related to the rotational speed and disk location. Research on vibrations of shaft-disk rotors in non-uniform thermal field is essential for the design of rotating machinery. In this paper, the dynamic model of axially loaded thin-walled shaft-disk rotors in axial non-uniform temperature field is developed, considering three-dimensional displacement fields of the shaft and disk. This model introduces the temperature-dependent properties of materials, and gyroscopic and centrifugal effects. Based on the Euler-Bernoulli beam theory and the Kirchhoff plate theory, Lagrange's equation is used to derive the differential equations of motion. By comparing with the results of the existing reference and finite element results, the accuracy of the present model is verified. The effects of the axial displacement of shaft, temperature-dependent material property, temperature difference, temperature distribution, disk position and axial preload on the free vibration of shaft-disk rotors are discussed. Results show that the present model can effectively predict free vibrations of shaft-disk rotors in axial non-uniform temperature field. The effect of thermal field on vibrations of shaft-disk rotors is affected by the rotational speed and disk location as well. [ABSTRACT FROM AUTHOR]

• A new strategy is proposed for vibration control of flexible pendulums. • We introduce a flywheel to control flexible pendulum vibration. • The control method has robustness and is effective for nonlinear forced vibration. • An experiment platform is built to validate the proposed control strategy. Flexible inverted pendulums have found wide applications in mechanical systems, but their stability is susceptible to external disturbances. In this study, a new strategy that employs a flywheel to suppress vibration of flexible inverted pendulums is proposed. We develop the theoretical dynamic model of flexible pendulums with a flywheel by the Euler-Bernoulli beam theory, where the axial displacement of the pendulum and geometric nonlinearities are considered. An active control method based on the Bézier trajectory is proposed, where the acceleration of the flywheel is set as the input. Additionally, the equivalent damping ratio of the system including flywheel's motion is derived. The relationship between the parameters in the control equation and the suppression effect is obtained through the simulation of the equivalent damping ratio. Then, an experimental platform is built. The experimental results show that the present control strategy has good suppression effect on the vibration of the flexible inverted pendulums when selecting appropriate parameters. Meanwhile, the results of anti-disturbance test show that the present method has a certain robustness. Finally, the simulation results show that this strategy is also effective for nonlinear forced vibration under different excitation frequencies. [ABSTRACT FROM AUTHOR]

• Nonlinear dynamics of bolted JCCSs are studied theoretically and experimentally. • Displacement-dependent characteristics in bolt connection zone are considered. • The developed model is capable of predicting nonlinear vibration of bolted JCCSs. • Experimental results validate the present theoretical model. This paper investigates the nonlinear dynamic characteristics of joined conical-cylindrical shells (JCCSs) with bolt connection for the first time. In the process of developing mechanical model of the bolt connection, the displacement-dependent stiffness and damping are taken into account, which could simulate the change of the contact state at the connection interface under different excitations. Both theoretical and experimental studies are performed to illustrate the nonlinear vibration behaviors of the bolted JCCSs. Successive uniform distributed artificial springs between the conical and cylindrical shells are adopted to simulate the rigid joint of the two shells. Donnell's shell theory is employed in theoretical modeling, and the governing equation is obtained by the Lagrange equation. The displacement admissible function applied in the research is Chebyshev polynomial. By comparison with existing literature and experimental data, the accuracy of present theoretical model is validated. It is found that both theory and experiment show a dynamic softening phenomenon with the increase of excitation level. Taking the displacement-dependent characteristics in bolt connection zone into consideration can effectively illustrate this soft phenomenon. The established model is capable of predicting the nonlinear vibration characteristics of JCCSs with bolt connection. [Display omitted] [ABSTRACT FROM AUTHOR]

This work analyzes the free vibration of a spinning functionally graded graphene platelet-reinforced metal foam (FG-GPLRMF) beam. The differential transformation method is extended to analyze flap-wise bending vibration and chordwise bending vibration with Coriolis force effect for the first time. The beam is modeled using the Euler–Bernoulli beam theory. The Halpin–Tsai micromechanics model is utilized to predict effective material properties. Various types of graphene platelet (GPL) and porosity distributions are considered. The governing equations and corresponding boundary conditions of the FG-GPLRMF beam are obtained via Hamilton's principle. Results show that the vibration characteristics of the FG-GPLRMF beam are affected by the GPL geometry size, types of porosity, and GPL distributions. Among different types of porosity, the Porosity-A causes the highest fundamental natural frequency, while the Porosity-B corresponds to the lowest one of the spinning FG-GPLRMF beam in most cases. Moreover, the GPL pattern and porosity distribution have a coupled effect on the bending vibration of the spinning FG-GPLRMF beam. [ABSTRACT FROM AUTHOR]

This study aims to perform free vibration and buckling analyses of circular cylindrical shells made of three-dimensional (3D) graphene foam. Three kinds of porosity distribution are considered including two kinds of symmetrical distribution and uniform distribution. The Kirchhoff-Love shell theory is utilized to establish the mathematical model of 3D graphene foam (3D-GF) shells. Natural frequencies and buckling loads of the shells under various boundary conditions are obtained via the Rayleigh-Ritz method in conjunction with Chebyshev polynomials. Results show that the mechanical characteristics of the 3D-GF shells are significantly affected by the porosity coefficient and porosity distribution. Moreover, the effect of porosity coefficient is closely related to boundary conditions of the shells. It is also shown that as the porosity coefficient increases, the porosity distribution effect on the mechanical characteristics of 3D-GF shells becomes increasingly significant. [ABSTRACT FROM AUTHOR]

This work investigated the wave propagation characteristics of buried pipes conveying viscous flowing fluid under axisymmetric wave motion, where the coupling pipe–soil and pipe–fluid effects are both taken into account. The fluid was assumed to be viscous, isotropic, and irrotational. The coupled equations of wave motion were obtained based on Love's thin shell theory. The analytical fluid-dominated (s=1) wave dispersion relations of buried fluid-conveying pipes are given. In addition, studies were carried out to scrutinize the effects of the soil, flow velocity, fluid viscosity, fluid mass density, and pipe geometry on wave propagation of buried fluid-conveying pipes. Results show that the higher fluid velocity can lead to larger phase velocity and smaller wave attenuation in buried pipes. In addition, viscous fluid leads to larger wave attenuation compared with ideal fluid. [ABSTRACT FROM AUTHOR]

• An effective mathematical model for bolted flange joints is proposed. • The proposed model is applicable for both bolt looseness and no-looseness conditions. • Experimental results validate the proposed model. • The soft nonlinearity characteristics of bolted flange joint multi-plate structure under base excitation are revealed. Bolted flange joints are widely used in various engineering structures to combine two or more substructures together. However, the understanding of mechanical mechanism of bolted flange joints is still insufficient due to the lack of efficient mathematical models. This paper proposes an effective mathematical model for bolted flange joints, which is then employed to conduct vibration analysis on bolted flange joint multiple-plate structures. During the modeling process, the flange is modeled by the Kirchhoff plate theory, and the bolted joints are modeled by the two-dimensional face constraint in bolted joint affected region (BJAR). The artificial spring technique is adopted to simulate the face constraint. The friction contact model and equivalent linearization technique are adopted to analyze the stick and slip states of bolted joints. By adopting the Chebyshev orthogonal polynomials as admissible functions, governing equations are derived. Then, the Rayleigh-Ritz method is applied to study the free vibration characteristics, and the Newmark-beta method is employed to study the vibration response under base excitation. The experimental studies are performed on the bolted flange joint two-plate structure (BFJTPS) to illustrate the effectiveness of the proposed theoretical model. The results indicate that the proposed mathematical model can well predict the vibration characteristics of multiple-plate structures under both bolt looseness and no-looseness conditions. The soft nonlinearity phenomenon under bolt looseness condition can be successfully revealed by the model. [ABSTRACT FROM AUTHOR]

It is very significant to improve the diameter accuracy of micro-shafts fabricated by micro-electrical discharge machining (micro-EDM) in micro-tools application. The diameter accuracy includes the uniformity of a single micro-shaft in axial direction and the repeatability of micro-shafts with the same diameter. A newly proposed method, named twin-mirroring-wire tangential feed electrical discharge grinding (TMTF-WEDG), can realize high uniformity and repeatability of micro-shafts via tangentially feeding and constraining of a narrow slit formed by a twin-mirroring-wire on the diameter of micro-shafts, respectively. Controlling the material removal thickness in single-step machining of micro-shafts is necessary to achieve high uniformity and repeatability. This paper focuses on the effects of the several important factors on the material removal thickness of micro-shafts to reveal the effects on the diameter uniformity and repeatability, including the open voltage, capacitance, feed rate in the Z-direction, feed step in the Y-direction, and tangential feed distance. The results indicate that the lower open voltage or the smaller capacitance or higher Z-direction feed rate, the smaller the thickness of the material removed, which is advantageous for controlling the consistency and repeatability of the micro-shafts. Decreasing of Y-direction feed step from 20 to 5 μm is accompanied by a reduction in material removal thickness, and the material removal thickness of less than 0.4 μm is achieved with a smaller feed step of in the Y-direction. As the tangential feed distance S2 decreases, the material removal thickness of the micro-shafts decreases gradually. In this study, the uniformity and repeatability of brass and tungsten micro-shafts are controlled within 1 μm and 2 μm, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we present vibration analysis of a metal foam core sandwich cylindrical thin shell via the Chebyshev collocation method. Three types of metal foam core are taken into account. The governing equations are derived using Hamilton's principle and the Kirchhoff‐Love shell theory. Then, the Chebyshev collocation method is developed to evaluate natural frequencies of the metal foam core sandwich cylindrical shell under various boundary conditions. Results show that the Chebyshev collocation method possesses high accuracy. Moreover, the Sym‐1 metal foam core leads to the largest stiffness of the shell while the Sym‐2 metal foam core leads to the smallest stiffness. The effects of porosity coefficient and core thickness are also highlighted on the vibration characteristics of the metal foam core sandwich cylindrical shell. [ABSTRACT FROM AUTHOR]

In this paper, free vibration of a metal foam core sandwich (MFCS) beam embedded in Winkler–Pasternak elastic foundation is studied using the Chebyshev collocation method (CCM). This method can achieve high precision within the range allowed by the effective number of bits of computers. Three foam distribution types along the thickness direction are considered for the core. The Timoshenko beam theory is adopted and Hamilton's principle is utilized to derive the boundary conditions and governing equations of the model. The numerical results show that natural frequencies of the sandwich beam initially increase and then decrease with the rise in thickness of metal foam core. By arranging the foam distribution in the core, natural frequencies of the sandwich beam can be significantly changed. Moreover, natural frequencies of the uniform foam distribution beam are insensitive to the foam coefficient. For the beam with non-uniform foam distribution, however, the natural frequencies increase or decrease with the foam coefficient, depending closely on the foam type. In addition, the present method is validated by comparing with the published ones for special cases. [ABSTRACT FROM AUTHOR]

The thermo-electro-mechanical nonlinear vibration of circular cylindrical nanoshells on the Winkler–Pasternak foundation is investigated. The nanoshell is made of functionally graded piezoelectric material (FGPM), which is simulated by the nonlocal elasticity theory and Donnell's nonlinear shell theory. The Hamilton's principle is employed to derive the nonlinear governing equations and corresponding boundary conditions. Then, the Galerkin's method is used to obtain the nonlinear Duffing equation, to which an approximate analytical solution is obtained by the multiple scales method. The results reveal that the system exhibits hardening-spring behavior. External applied voltage and temperature change have significant effect on the nonlinear vibration of the FGPM nanoshells. Moreover, the effect of power-law index on the nonlinear vibration of the FGPM nanoshells depends on parameters such as the external applied voltage, temperature change and properties of the Winkler–Pasternak foundation. [ABSTRACT FROM AUTHOR]

In this paper, free vibrations of cylindrical nanoshells made of nanoporous metal foam are investigated for the first time. Based on the modified couple stress theory and Love's thin shell theory, the governing equations of the present system are derived by using Hamilton's principle. Two types of nanoporosity distribution are considered in the construction of the nanoporous shells. Then, the Navier method and Galerkin method are utilized to solve natural frequencies of the nanoporous shells under different boundary conditions. Afterwards, a detailed parametric study is conducted. Results show that the nanoporosity type, the material length scale parameter, the porosity coefficient, the length-to-radius ratio, and the radius-to-thickness ratio play important role on the free vibrations of nanoporous shells. To check the validity of the present analysis, the results are compared with those in previous studies for the special cases. [ABSTRACT FROM AUTHOR]

In this study, the thermo-hygro-mechanical bending and vibration of functionally graded material (FGM) microbeams with microporosity defect are investigated. The mathematical model of the system is developed by using the sinusoidal beam theory and the modified couple stress theory. Based on Hamilton's principle, the governing equations and boundary conditions of imperfect FGM microbeams are derived. Then, Navier's method is utilized to calculate the deflections and natural frequencies of the system. Analytical results are presented to illustrate the effects of the microporosity volume fraction, the microporosity distribution type, the power-law index, the temperature and the moisture on the static bending and free vibration of imperfect FGM microbeams. [ABSTRACT FROM AUTHOR]

• A universal theoretical model for bolted joint plates is established. • The flange effect is considered. • Theoretical results are improved by considering the pressure distribution in BJAR. • Experimental results validate the present theoretical model. The bolted joint multi-plate structures are widely used in practical engineering, but their theoretical dynamic model is hard to find in literature. The main purpose of this paper is to establish a general dynamic model of bolted joint multi-plate structures with flanges, and to investigate its vibration characteristics from both theoretical and experimental aspects. Both the flange effect and contact pressure distribution in the bolted joint affected region (BJAR) are considered. Artificial spring sets with variable stiffness are adopted to simulate the non-uniform distributed contact pressure in BJAR. The governing equations are derived based on the Kirchhoff plate theory and Euler-Bernoulli beam theory. The Chebyshev polynomials are used as admissible displacement functions. Then, the free vibration and forced vibration under base excitation are solved by means of the Rayleigh-Ritz method and Newmark-beta method, respectively. The experimental studies, including modal test and vibration response test, are conducted on a bolted joint two-plate specimen to verify the accuracy of the theoretical model. Results show that the present model is capable of realizing reliable vibration prediction and can be conveniently extended to the structure with an arbitrary number of plates and bolts. For the bolted structures, considering the pressure distribution in the connection interfaces can significantly improve the accuracy of theoretical results. [Display omitted] [ABSTRACT FROM AUTHOR]

Aim. Cyclophilin A (CypA)/CD147 signaling plays critical roles in the regulation of inflammation and bone metabolism. This study aimed to investigate the participation of CypA/CD147 in mice periapical lesions progression and its relationship with bone resorption. Methodology. Periapical lesions were induced by pulp exposure in the first lower molars of 40 C57BL/6J mice. The mice were sacrificed on days 0, 7, 14, 21, 28, 35, 42, and 49. Mandibles were harvested for X-ray imaging, microcomputed tomography scanning, histologic observation, immunohistochemistry, enzyme histochemistry, and double immunofluorescence analysis. Western blot was employed to further detect the related molecular signaling pathways in LPS-stimulated RAW 264.7 cells treated with CypA inhibitor. Results. The volume and area of the periapical lesions increased from day 0 to day 35 and remained comparably stable until day 49. Immunohistochemistry demonstrated that the CypA expression levels also increased from day 0 to day 35 and decreased until day 49, similar to CD147 expression (R2 = 0.4423, P < 0.05), osteoclast number (R2 = 0.5101, P < 0.01), and the expression of osteoclastogenesis-related matrix metalloproteinase 9 (MMP-9) (R2 = 0.4715, P < 0.05). Serial sections further confirmed the colocalization of CypA and CD147 on osteoclasts with immunohistochemistry. And the distribution of CypA-positive or CD147-positive cells was positively correlated with the dynamics of MMP-9-positive cells by using immunofluorescence analysis. Furthermore, CD147 and MMP-9 expression in RAW 264.7 cells were both downregulated with CypA inhibitor treatment (P < 0.05). Conclusions. The present study reveals the positive correlation of CypA/CD147 signaling and osteoclast-related MMP-9 expression in mice inflammatory periapical lesions progression. Therefore, intervention of CypA/CD147 signaling could probably provide a potential therapeutic target for attenuating inflammatory bone resorption. [ABSTRACT FROM AUTHOR]

Abstract This paper performs nonlinear vibration analysis of metal foam circular cylindrical shells reinforced with graphene platelets. An improved Donnell nonlinear shell theory is employed to formulate the present model. The graphene platelet reinforced material properties are evaluated by the Halpin–Tsai equation. Different types of porosity and graphene platelet (GPL) distribution are taken into account. Governing equations are derived via Hamilton's principle and then they are transformed to ordinary differential equations using the Galerkin method. Afterwards, nonlinear frequencies of the system are solved by using the multiple scale method. Our findings demonstrate that GPL reinforced metal foam (GPLRMF) shells exhibit hardening-spring vibration characteristics. The nonlinear to linear frequency ratio of the shell closely relates to the porosity distributions and GPL patterns. The effect of geometrical size of graphene platelets on nonlinear vibration characteristics of GPLRMF cylindrical shells is also highlighted. [ABSTRACT FROM AUTHOR]

Abstract In the present work, nonlinear dynamics of fluid-conveying functionally graded material (FGM) sandwich nanoshells is investigated. In order to describe the large-amplitude motion, the von Kármán nonlinear geometrical relations are taken into account. Compressibility and viscidity of the fluid are neglected, and the velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the nanoshells. Based on the classical shell theory and incorporating the surface stress effect, the governing equations are derived by using Hamilton's principle. After that, the Galerkin method is used to discretize the equation of motion, resulting in a set of ordinary differential equations with respect to time. The ordinary differential equations are solved analytically by utilizing the method of multiple scales. Results show that the surface stress plays important roles on the nonlinear vibration characteristics of fluid-conveying FGM sandwich thin-walled nanoshells. Furthermore, the fluid speed, the power-law index, the fluid mass density, the core thickness and the initial surface tension can also influence the vibration characteristics of fluid-conveying FGM sandwich nanoshells. Highlights • A fluid-conveying functionally graded sandwich nanoshell model is developed. • Surface stress influence is considered in the present analysis. • Thin shell theory is employed to model the fluid-conveying nanotube. • Nonlinear vibration of fluid-conveying FGM sandwich nanoshells is studied analytically. [ABSTRACT FROM AUTHOR]

• IL-33/ST2 signaling participate in the acute and chronic pain. • IL-33/ST2 signaling play a role in the chronic itch. • IL-33/ST2 signaling modulate the pathogenesis of pain and pruritus at both peripheral and central levels. Interleukin-33 (IL-33) is an inflammatory factor with an extensive range of biological effects and pleiotropic roles in diseases. Evidence suggests that IL-33 and its receptor ST2 play a pivotal role in chronic pain and itch at the level of primary sensory neurons, the spinal cord, and the brain. In this review, we outline an evolving understanding of the roles and mechanisms of IL-33 in chronic pathological pain, including inflammatory, neuropathic, and cancer, and chronic pruritus, such as allergic contact dermatitis, atopic dermatitis, and dry skin. Understanding the key roles of IL-33/ST2 signaling may provide exciting insights into the mechanisms of chronic pain and itch and lead to new clues for therapeutic approaches to the resolution of chronic pain and itch. [ABSTRACT FROM AUTHOR]

• Vibrations of JCCSs with bolt loosening boundary are studied theoretically and experimentally. • Non-uniform arc constraint is established to simulate the bolt loosening boundary. • The developed model is reliable in estimating the dynamic behaviors of bolted JCCSs with different loosening degrees. • Experimental results validate the present theoretical model. This paper investigated the vibration characteristics of joined conical-cylindrical shells (JCCSs) with bolt loosening boundary conditions both theoretically and experimentally. The non-uniform arc constraint model is established to simulate the bolt loosening boundary conditions by the artificial spring technology, which can describe the actual bolt contact pressure distribution. Continuously distributed artificial springs are introduced to realize the connection of the conical and cylindrical shells. Donnell's shell theory and Chebyshev polynomials are adopted to establish the theoretical model, and the dynamic equation is derived from the Lagrange equation. The validity of the present model is verified by the available literature, hammer test and vibration shaker test. The results indicate that the maximum errors of natural frequencies and resonant displacements are less than 4.41% and 18.6%, respectively. It is found that bolt loosening has a significant effect on the fundamental frequency, but it gradually weakens with the increase of the mode order. Increasing bolt loosening degree can lead to an increment of resonant displacement. The developed model is reliable in estimating the dynamic behaviors of bolted JCCSs with different loosening degrees, and it contributes to providing guidance in the design and service process of combined shell structures. [ABSTRACT FROM AUTHOR]

Modeling and dynamic analysis of bolted joint plates under general boundary conditions are presented in this study, where the flange geometry is considered. An artificial spring technique is utilized to simulate the general boundary conditions and connection of bolts. The energy functions of plates and flanges are obtained based on the Kirchhoff and Euler-Bernoulli beam theories, respectively. Then, by taking the Chebyshev polynomials as admissible functions, the Lagrangian approach is applied to obtain the equations of motion for the bolted joint plates. The discretized motion equation is obtained by employing the assumed mode method. The accuracy of the present method is verified by comparing the results with those from ANSYS. Finally, parametric studies are performed to analyze the effect of boundary spring stiffness, flange geometry parameters, the bolt number and its connecting stiffness, and the plate size on the vibration properties of bolted joint plates. The results indicate that there exist abundant frequency veering and mode shift phenomena in the bolted joint multi-plate structures. • A general dynamic model for bolted joint multi-plate structures is established. • Both the flange effect and arbitrary boundary conditions are considered. • Frequency veering and mode shift phenomena are discovered in this structure. [ABSTRACT FROM AUTHOR]

This paper examines the nonlinear dynamics of a translational functionally graded material (FGM) plate. The plate is composed of nickel and stainless steel, and its property is graded in the thickness direction that obeys a power-law distribution. By adopting the Kármán nonlinear geometrical relations, the equation of motion is derived from the D'Alembert's principle by considering the dynamic equilibrium relationships for the out-of-plane vibration of the plate. The equation of motion is discretized by using the Galerkin method and thus a series of ordinary differential equations with mode-coupling terms are obtained. These ordinary differential equations are then solved by utilizing the method of harmonic balance. The analytical results are verified by the adaptive step-size fourth-order Runge-Kutta technique. The stability analysis of analytical solutions is also carried out by introducing small perturbation for steady state solutions. Both natural frequency and nonlinear frequency-amplitude characteristics are presented. In the translational FGM plate, strong nonlinear mode interaction phenomenon has been detected. The nonlinear frequency response shows intensive hardening-spring characteristics. Moreover, various system parameters such as power-law distribution, translating speed of the plate, in-plane tension force, damping coefficient and external excitation amplitude are selected as the controlled variables to present parametric study. Their effects on the nonlinear dynamical response of the translational FGM plate are highlighted. [ABSTRACT FROM AUTHOR]

To provide reference for aerospace structural design, electro-mechanical vibrations of functionally graded piezoelectric material (FGPM) plates carrying porosities in the translation state are investigated. A modified power law formulation is employed to depict the material properties of the plates in the thickness direction. Three terms of inertial forces are taken into account due to the translation of plates. The geometrical nonlinearity is considered by adopting the von Kármán non-linear relations. Using the d’Alembert's principle, the nonlinear governing equation of the out-of-plane motion of the plates is derived. The equation is further discretized to a system of ordinary differential equations using the Galerkin method, which are subsequently solved via the harmonic balance method. Then, the approximate analytical results are validated by utilizing the adaptive step-size fourth-order Runge-Kutta technique. Additionally, the stability of the steady state responses is examined by means of the perturbation technique. Linear and nonlinear vibration analyses are both carried out and results display some interesting dynamic phenomenon for translational porous FGPM plates. Parametric study shows that the vibration characteristics of the present inhomogeneous structure depend on several key physical parameters. [ABSTRACT FROM AUTHOR]

Interleukin (IL)-33 is a member of the interleukin-1 cytokine family that is produced by many different types of tissues including the central nervous system (CNS). IL-33 mediates its effects via its heterodimeric receptor complex, comprised of ST2 and the IL-1 receptor accessory protein (IL-1RAcp). As a pleiotropic nuclear cytokine, IL-33 is a crucial factor in the development of cardiovascular diseases, allergic diseases, infectious diseases, and autoimmune diseases. Recently, accumulated evidence shows that the IL-33/ST2 axis plays a crucial and diverse role in the pathogenesis of CNS diseases, including neurodegenerative diseases, cerebrovascular diseases, infectious diseases, traumatic CNS injury, chronic pain, etc. In this review, we discuss the recent findings in the cellular signaling of IL-33 and advancement of the role of IL-33 in several CNS diseases, as well as its therapeutic potential for the treatment of those diseases. [ABSTRACT FROM AUTHOR]

Vibrations of longitudinally traveling functionally graded material (FGM) plates with porosities are studied for the first time. The FGM plates contain porosities owing to the technical issues during the preparation of FGMs. Two different porosity distributions, namely, even and uneven distribution, are considered in this paper. The large-amplitude motion of FGM plates is taken into account so that the present model includes both geometry and material nonlinearities. The governing equation of the present system is derived by using the D'Alembert's principle. The Galerkin method is utilized to discretize the governing equation to a system of ordinary differential equations. The method of harmonic balance is adopted to perform an approximately analytical analysis on the present model. Then the analytical results are validated by the comparison with numerical solutions, which are obtained by using the adaptive step-size fourth-order Runge-Kutta method. Moreover, the stability of steady-state analytical solutions is analyzed. Nonlinear vibrational responses for both FGM plates with evenly distributed porosities (EDP) and unevenly distributed porosities (UEDP) are examined. A 1:1 internal resonance behavior is discovered and it is found that this behavior can be excited by very small external excitation. Furthermore, the effects of porosity volume fraction, damping and constituent volume fraction on the dynamic response of the system are highlighted. [ABSTRACT FROM AUTHOR]

A first known study is conducted on the vibrations of functionally graded material (FGM) rectangular plates with porosities and moving in thermal environment. The FGM plates contain porosities owing to the technical issues during the preparation of FGMs. Two types of porosity distribution, namely, even and uneven distribution, are considered. The geometric nonlinearity is taken into account by using von Kármán nonlinear plate theory. The out-of-plane equation of motion of the system is derived based on the D'Alembert's principle with the consideration of the thermal effect and longitudinal speed. Then the Galerkin method is employed to discretize the partial differential equation of motion to a set of ordinary differential equations. These time-varying ordinary differential equations are solved analytically by means of the method of harmonic balance. The accuracy of approximately analytical solutions is verified by the adaptive step-size fourth-order Runge–Kutta technique. Additionally, the stability of steady-state solutions is analyzed for the analytical solutions. Vibration characteristics such as natural frequency and nonlinear frequency response are shown. The present model is a hardening-spring system based on the nonlinear frequency response results. Effects of some key parameters are investigated on the vibration of rectangular FGM plates with porosities and moving in thermal environment. [ABSTRACT FROM AUTHOR]

This research focuses on the large-amplitude vibration of sigmoid functionally graded material (S-FGM) thin plates with porosities. Porosities in S-FGM plates can happen due to technical issues during the preparation of S-FGMs. Two types of porosity distribution, i.e., even and uneven distribution, are taken into account. The material properties of S-FGM plates with porosities change smoothly along the thickness direction based on the sigmoid distribution law, which is described by modified piecewise functions. The geometrical nonlinearity is considered by applying the von Kármán non-linear plate theory. The nonlinear governing equation of S-FGM plates with porosities is derived using the D′Alembert's principle. By applying the Galerkin method with the first three modes, the governing equation is discretized to three ordinary differential equations. Then, the method of harmonic balance is used to solve these discretized equations. Analytical results are verified numerically with the adaptive step-size fourth-order Runge-Kutta method. The stability of the steady-state response is examined by means of the perturbation technique. Furthermore, the maximum amplitudes of each mode during the vibration period are obtained and shown in the neighborhood of the fundamental mode. Study demonstrates that the S-FGM plates with porosities possess hardening spring characteristics in nonlinear frequency response. Moreover, a complex multi-solution phenomenon occurs in the present dynamic system which is rooted from the nonlinear mode interaction. Finally, investigation is made on the effects of porosity along with other key parameters on large-amplitude vibration response of porous S-FGM plates. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvesting is envisioned as an ideal complement to batteries for long-life operation of wireless or remote electronic devices. Most piezoelectric energy harvesters (PEHs) utilize piezoelectric plates or discs as the energy transducing elements, and they cannot generate enough power for most potential applications. In this study, we explore a new way of using arc-shaped piezoelectric patches as the core transducing elements in energy harvesters to improve their performance. An analytical model is developed via the Castigliano’s theorem to elucidate the low stiffness characteristic of the arc-shaped structure. A finite element analysis is conducted, and the results indicate that high and evenly-distributed stress can be easily induced in the arc-shaped PEHs. Prototypes are fabricated with arc-shaped piezoelectric elements and flat piezoelectric plates, respectively, and tested under the same conditions. The experimental data demonstrate that the arc-shaped PEHs are capable of generating 2.55–4.25 times as much power as the equivalent flat-plate PEHs. This study lays the foundation to enhance energy harvester performance by utilizing arc-shaped piezoelectric structures. [ABSTRACT FROM AUTHOR]

This paper develops a semi-analytical method for solving the frequency response of spinning cylindrical shells. The dynamic model of the spinning cylindrical shells with discontinuous boundary conditions is established. In the modeling, Sanders' shell theory is employed and Chebyshev polynomials are adopted as the admissible displacement functions. By using the Lagrange equation, the equation of motion is obtained. Then, the equation is transformed into a state-space form, wherein the orthogonality of complex eigenvectors is derived. Further, the equation of motion is decoupled on the basis of the complex mode theory. Utilizing the reduced complex eigenvector, a semi-analytical method for solving the frequency response of the spinning shells is finally developed, wherein the point and distributed harmonic loads are all considered. The influences of the damping coefficient, the spinning speed, and the boundary spring stiffness on the frequency response of the shells are analyzed. The proposed method can conveniently predict the vibration characteristics of spinning cylindrical shells through a reduced-order dynamic model, which is much more efficient than numerical methods. • A semi-analytical method for solving the frequency response of spinning cylindrical shells is developed. • Discontinuous boundary conditions are introduced by artificial springs technology. • Complex mode theory is applied to decouple the equation of motion. • Frequency-response explicit functions for both point and distributed harmonic loads are obtained. [ABSTRACT FROM AUTHOR]

This study investigates nonlinear dynamic thermoelastic response of functionally graded material (FGM) plates with longitudinal velocity for the first time. The large amplitude motion of FGM plates is considered so that the present model includes both geometry and material nonlinearities. Based on the D'Alembert's principle, the out-of-plane equation of motion of the system is obtained by considering the thermal effect and the longitudinal velocity. After that, the Galerkin method is employed to discretize the partial differential equation of motion to a set of ordinary differential equations. The method of harmonic balance is used to solve analytically the time-varying set of ordinary differential equations. The approximately analytical solutions are verified by numerical solutions utilizing an adaptive step-size fourth-order Runge-Kutta technique. Furthermore, the stability of steady-state response is analyzed for the approximately analytical solutions. The linear frequency characteristics and nonlinear frequency-response characteristics are both presented for the system. The nonlinear frequency-response relationships demonstrate strong hardening-type behavior of the system. Results are shown to examine the influences of different parameters including longitudinal velocity, temperature, constituent volume distribution, in-plane pretension, damping and force amplitude on the nonlinear dynamic thermoelastic response of FGM plates with longitudinal velocity. [ABSTRACT FROM AUTHOR]

This study investigates the nonlinear steady-state responses of longitudinally traveling functionally graded material (FGM) plates immersed in liquid for the first time. The liquid is assumed to be ideal, and therefore it is inviscid, incompressible and irrotational. The velocity potential and Bernoulli’s equation are utilized to describe the dynamic liquid pressure. The large amplitude motion of the FGM plate is considered so that the present model includes both geometry and material nonlinearities. Based on the Newton’s second law, the equation of out-of-plane motion of the plate is obtained. The Galerkin method is used to discretize the partial differential equation of motion and then the method of harmonic balance is used to analytically solve a set of ordinary differential equations. Also, the numerical solutions are carried out by utilizing an adaptive step-size fourth-order Runge-Kutta technique. The analytical and numerical results agree with each other quite well. Furthermore, the stability of steady-state solutions is performed for the analytical results. The frequency characteristics, time- and frequency-domain response characteristics of the plate are fully discussed. The nonlinear frequency-response relationships show strong hardening-type behavior of the system. Additionally, the influences of different parameters on the nonlinear dynamical responses of the system are shown. [ABSTRACT FROM AUTHOR]

The title complex, {[Zn(ODIB)( bpdc)]·2DMF} was prepared under hydrothermal conditions (dimethylformamide and water) based on two ligands, namely, 1,1′-oxy-bis[3,5-diimidazolyl-benzene] (ODIB) and biphenyldicarboxylic acid (H bpdc). ODIB ligands link Zn cations to give layers in crystal. bpdc anions coordinate to Zn atoms, however, their introduction does not increase the dimension of the structure. Each layer is partially passes through the adjacent layers in the offset ABAB manner. [ABSTRACT FROM AUTHOR]

Internal resonances in circular cylindrical shells, induced by the spinning motion, are explored in this research. The mathematical model of spinning cylindrical shells is established by employing Donnell's nonlinear shell theory and the Lagrange equations of motion. Then, the nonlinear forced vibration responses of the shells are solved by using the pseudo-arclength continuation technique. Some comparisons are conducted to verify the accuracy of the present model and method The results show that internal resonances can be caused by the spinning motion of the shells, which cover a wide range of spinning speeds. Different types of internal resonances can occur, such as 1:1, 1:1:1, and 1:2 internal resonances. Energy exchanges between different modes with internal resonance relationships. Both softening and hardening nonlinearities exist in the frequency response of the spinning cylindrical shells. The excitation amplitude has a threshold to excite the internal resonances. It is found that the internal resonances can be avoided by tuning the spinning speed of the shells. • Internal resonances can be induced by the spinning motion of circular cylindrical shells. • Internal resonances in circular cylindrical shells cover a wide range of spinning speeds. • Different types of internal resonances are discovered in spinning circular cylindrical shells. • Internal resonances can be avoided by tuning the spinning speed of the shells. [ABSTRACT FROM AUTHOR]

Based on the first-order shear deformation theory (FSDT) for shells, the free vibration of a spinning functionally graded (FG) spherical–cylindrical–conical (SCC) shell with arbitrary boundary conditions subjected to a thermal environment is investigated. The centrifugal forces, the Coriolis forces, and the initial hoop tension caused by spin are all considered in the theoretical modeling. The model is analyzed using the domain decomposition method. The penalty method is used to model the continuity and arbitrary boundary conditions. Validity study is performed by comparing with the results from finite element analyses for special cases. Finally, the effects of the power-law index, the temperature loads, the spinning speed, and the geometrical parameters on the free vibration characteristics, as well as the influences of structural configuration on the critical spinning speed, are investigated. It is found that the configuration of a spinning SCC shell has significant effect on its natural frequency and critical speed under a fixed shell weight. The natural frequencies approximately converge into three values with increases in the circumferential wave number. The FG–SCC shell's cone angles at which the minimum and maximum natural frequencies occur are not affected by the spinning speed and the power-law index. • Traveling wave vibration of spinning FG spherical–cylindrical–conical shells is investigated. • Arbitrary boundary conditions and thermal effect are considered. • Shell configuration effect on natural frequencies is studied. • The critical speed of the spinning shells is explored. [ABSTRACT FROM AUTHOR]

For the purpose of understanding the vibrational characteristics of moving plates in continuous hot-dip galvanizing process, the linear and nonlinear free vibrations of an axially moving rectangular plate coupled with dense fluid having a free surface are investigated. The fluid is assumed to be incompressible, inviscid and irrotational in this study. Effect of free surface waves of the fluid is taken into account in the analysis. The classical thin plate theory is adopted to formulate the equation of motion of the vibrating plate. The velocity potential and Bernoulli׳s equation are used to describe the fluid pressure acting on the moving plate. The effect of fluid on the vibrations of the plate may be equivalent to added mass of the plate. The system is solved by applying directly the method of multiple scales to the governing partial-differential equations and boundary conditions. Results show the immersion depth, moving speed, fluid-plate density ratio, stiffness ratio and aspect ratio all have significant effects on the natural frequencies of the immersed moving plate. The nonlinear frequencies of the plate-fluid system are influenced by initial amplitude, moving speed and nonlinear coefficient. It is also shown that the 1:1 and 1:3 internal resonances of the immersed moving plate can occur at certain speeds. Owing to the internal resonance, amplitude ratio of the two internal resonance modes shows multi-value characteristics. With the increase of nonlinear coefficient, the internal resonance phenomenon becomes more and more intense. [ABSTRACT FROM AUTHOR]

In the present study, the experimental and theoretical methods were used to analyze the binding interaction of food dye, curcumin with trypsin. The results of fluorescence spectroscopic measurements indicated that curcumin binding resulted in the obviously intrinsic fluorescence quenching with the increase concentration of curcumin. This binding interaction is a spontaneous process with the estimated enthalpy and entropy changes being −15.70 kJ mol −1 and 40.25 J mol −1 K −1 , respectively. Hydrogen bonds and hydrophobic forces played an important role in the complex formation between curcumin and trypsin. Moreover, curcumin could enter into the primary substrate-binding pocket and makes the activity of trypsin decrease remarkably with the increasing concentration of curcumin. [ABSTRACT FROM AUTHOR]

The vibration characteristics of an axially moving vertical plate immersed in fluid and subjected to a pretension are investigated, with a special consideration to natural frequencies, complex mode functions and critical speeds of the system. The classical thin plate theory is adopted for the formulation of the governing equation of motion of the vibrating plates. The effects of free surface waves, compressibility and viscidity of the fluid are neglected in the analysis. The velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the moving plate. The effect of fluid on the vibrations of the plate may be regarded as equivalent to an added mass on the plate. The formulation of added mass is obtained from kinematic boundary conditions of the plate-fluid interfaces. The effects of some system parameters such as the moving speed, stiffness ratios, location and aspect ratios of the plate and the fluid-plate density ratios on the above-mentioned vibration characteristics of the plate-fluid system are investigated in detail. Various different boundary conditions are considered in the study. [ABSTRACT FROM AUTHOR]

A comprehensive study of the effects of C.I. Food Red 9 on the conformation and activity of pepsin was performed using multi-spectral methods and molecular docking technique. Fluorescence and circular dichroism spectral analyzes showed that C.I. Food Red 9 binding induced the changes of secondary and tertiary structure of pepsin. The activity experimental results indicated that the activity of pepsin decreased remarkably with the increasing concentration of C.I. Food Red 9. Multi non-covalent interactions including hydrogen bonds, hydrophobic, and electrostatic forces played important roles in the complex formation between C.I. Food Red 9 and pepsin. The binding constants of pepsin with C.I. Food Red 9 were (1.21 ± 0.036) × 10 4 L mol −1 (298 K) and (1.05 ± 0.043) × 10 4 L mol −1 (310 K). Moreover, the putative binding site of C.I. Food Red 9 on pepsin was near to activity pocket. This study demonstrates that C.I. Food Red 9 could cause some negative effects on pepsin. [ABSTRACT FROM AUTHOR]

A simple route to prepare ordered mesoporous silica with a uniform pore size distribution was reported, which was synthesized at quasi-neutral pH with the assistance of phosphate using sodium silicate as a silicon source. The products prepared at various pH were investigated and ordered mesoporous silica with a uniform pore structure was synthesized at a pH of 6.15. [ABSTRACT FROM AUTHOR]

Bisphenol A and its analogues have carcinogenic potentials and toxicities. However, there are lacks of studies elucidating gene toxic interactions of bisphenols with DNA. In this work, the binding modes of five bisphenol compounds with calf thymus DNA were characterized. The multi-spectroscopic experimental results indicated that the fluorescence quenching of bisphenols by calf thymus DNA point to groove binding. The ultraviolet visible and circular dichroism spectral data displayed that bisphenols partly induced conformational changes of calf thymus DNA. In addition, the binding constants of bisphenol A, diphenolic acid, bisphenol AF, bisphenol AP, bisphenol fluorine with calf thymus DNA obtained from fluorescence emission spectra were 1.09 × 10 4 , 3.65 × 10 4 , 4.46 × 10 4 , 1.69 × 10 4 , 4.49 × 10 4 L mol −1 at 298.15 K, which indicated that the multi-noncovalent binding forces were involved in the binding processes. In silico investigations indicated that DNA has the preferable binding sites binding with bisphenols by minor groove binding and electrons transfer from DNA bases to bisphenols occurred. In addition, the structural differences of these five bisphenols partly affected the binding ability of them with DNA. [ABSTRACT FROM AUTHOR]