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Immunotherapy is an emerging antitumor modality with high specificity and persistence, but its application for resected tumor treatment is impeded by the low availability of tumor-specific antigens and strong immunosuppression in the wound margin. Here a nanoengineered hydrogel is developed for eliciting robust cooperative ferroptosis-immunotherapeutic effect on resected tumors. Specifically, β-cyclodextrin (β-CD) is first grafted onto oxidized sodium alginate (OSA) through Schiff base ligation, which could trap cRGD-modified redox-responsive Withaferin prodrugs (WA-cRGD) to obtain the hydrogel building blocks (Gel@WA-cRGD). Under Ca2+-mediated crosslinking, Gel@WA-cRGD rapidly forms physiologically stable hydrogels, of which the porous network is used to deliver programmed cell death ligand 1 antibodies (aPD-L1). After injection into the post-surgical wound cavity, the β-CD-entrapped WA-cRGD is detached by the local acidity and specifically internalized by residual tumor cells to trigger ferroptosis, thus releasing abundant damage-associated molecular patterns (DAMPs) and tumor-derived antigens for activating the antigen-presenting cell-mediated cross-presentation and downstream cytotoxic T cell (CTL)-mediated antitumor responses. Furthermore, aPD-L1 could block PD-1/PD-L1 interaction and enhance the effector function of CTLs to overcome tumor cell-mediated immunosuppression. This cooperative hydrogel-based antitumor strategy for ferroptosis-immunotherapy may serve as a generally-applicable approach for postoperative tumor management. To overcome the immunosuppressive microenvironment in resected solid tumors for enhanced patient survival, here we report a nanoengineered hydrogel incorporated supramolecular redox-activatable Withaferin prodrug and PD-L1 antibody, which could elicit robust cooperative ferroptosis-immunotherapeutic effect against residual tumor cells in the surgical bed to prevent tumor relapse, thus offering a generally-applicable approach for postoperative tumor management. [Display omitted] [ABSTRACT FROM AUTHOR]

Radiotherapy is a mainstream modality for breast cancer treatment that employs ionizing radiation (IR) to damage tumor cell DNA and elevate ROS stress, which demonstrates multiple clinically-favorable advantages including localized treatment and low invasiveness. However, breast cancer cells may activate the p53-mediated cell cycle regulation in response to radiotherapy to repair IR-induced cellular damage and facilitate post-treatment survival. F-Box and WD Repeat Domain Containing 7 (FBXW7) is a promoter of p53 degradation and critical nexus of cell proliferation and survival events. Herein, we engineered a cooperative radio-ferroptosis-stimulatory nanomedicine through coordination-driven self-assembly between ferroptosis-inducing Fe2+ ions and FBXW7-inhibiting DNAzymes and further modification of tumor-targeting dopamine-modified hyaluronic acid (HA). The nanoassembly could be selectively internalized by breast cancer cells and disintegrated in lysosomes to release the therapeutic payload. DNAzyme readily abolishes FBXW7 expression and stabilizes phosphorylated p53 to cause irreversible G2 phase arrest for amplifying post-IR tumor cell apoptosis. Meanwhile, the p53 stabilization also inhibits the SLC7A11-cystine-GSH axis, which combines with the IR-upregulated ROS levels to amplify Fe2+-mediated ferroptotic damage. The DNAzyme-Fe-HA nanoassembly could thus systematically boost the tumor cell damaging effects of IR, presenting a simple and effective approach to augment the response of breast cancer to radiotherapy. To overcome the intrinsic radioresistance in breast cancer, we prepared co-assembly of Fe2+ and FBXW7-targeted DNAzymes and modified surface with dopamine conjugated hyaluronic acid (HA), which enabled tumor-specific FBXW7-targeted gene therapy and ferroptosis therapy in IR-treated breast cancers. The nanoassembly could be activated in acidic condition to release the therapeutic contents. Specifically, the DNAzymes could selectively degrade FBXW7 mRNA in breast cancer cells to simultaneously induce accumulation of p53 and retardation of NHEJ repair, eventually inducing irreversible cell cycle arrest to promote apoptosis. The p53 stabilization would also inhibit the SLC7A11/GSH/GPX4 axis to enhance Fe2+ mediated ferroptosis. These merits could act in a cooperative manner to induce pronounced tumor inhibitory effect, offering new approaches for tumor radiosensitization in the clinics. [Display omitted] [ABSTRACT FROM AUTHOR]

• This paper presents a solution methodology for the rotor system with bolted joint. • The presented solution methodology is verified by the Newmark method. • The 3X and 5X of the rotating frequency are found in the spectrum. • The rotating speed corresponding to 5X's peak precedes the critical speed. • The findings of spectral characteristics are verfied by the experimental test. The bolted joint is commonly used to connect several parts of aero-engine rotor system. Several papers have studied the nonlinear vibration responses of bolted rotor systems. However, the frequency spectrum characteristics of bolted rotor systems are not fully revealed. Aiming at this issue, this study develops a dynamic model of the bolted rotor system, where the piecewise stiffness characteristic is considered. A solution methodology is presented by incorporating the piecewise stiffness into the incremental harmonic balance method. The effects of unbalance and preload on the dynamic characteristics are discussed. Moreover, the stiffness and damping of the support structure and bolted joint are identified based on the particle swarm optimization algorithm and experimental results. Furthermore, the experimental study on a bolted rotor test rig is conducted to verify the accuracy of the identified parameters and the model. The simulation and experimental results indicate that 3X and 5X of the rotating frequency can be observed. Besides, the rotating speed corresponding to 5X's peak is different from the critical speed, and the peak of 5X precedes the primary resonance peak. [ABSTRACT FROM AUTHOR]

Recent insights collectively suggest the important roles of lysyl oxidase (LysOX) in the pathological processes of several acute and chronic neurological diseases, but the molecular regulatory mechanisms remain elusive. Herein, we explore the regulatory role of LysOX in the seizure-induced ferroptotic cell death of neurons. Mechanistically, LysOX promotes ferroptosis-associated lipid peroxidation in neurons via activating extracellular regulated protein kinase (ERK)-dependent 5-lipoxygenase (Alox5) signaling. In addition, overexpression of LysOX via adeno-associated viral vector (AAV)-based gene transfer enhances ferroptosis sensitivity and aggravates seizure-induced hippocampal damage. Our studies show that pharmacological inhibition of LysOX with β -aminopropionitrile (BAPN) significantly blocks seizure-induced ferroptosis and thereby alleviates neuronal damage, while the BAPN-associated cardiotoxicity and neurotoxicity could further be reduced through encapsulation with bioresponsive amorphous calcium carbonate-based nanocarriers. These findings unveil a previously unrecognized LysOX-ERK-Alox5 pathway for ferroptosis regulation during seizure-induced neuronal damage. Suppressing this pathway may yield therapeutic implications for restoring seizure-induced neuronal injury. A previously unrecognized LysOX/ERK/Alox5 signaling axis for ferroptosis regulation during seizure-induced neuronal damage is delineated. Selective inhibition of this pathway provides a therapeutic approach for treating post-seizure neuronal impairment. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Trace elements may affect neurodevelopment. There is a lack of data on breast-milk rubidium (Rb) in relation to neurodevelopment in infants. The associations of copper (Cu), zinc (Zn) and strontium (Sr) with neurodevelopment in infants remain uncertain.Objectives: We sought to evaluate the associations of breast-milk Rb (primary exposure), Cu, Zn, and Sr with neurodevelopment in infants at age 8 months.Methods: The study cohort included 117 breastfed infants. Breast-milk samples were collected at 42 days and 8 months postpartum. Breast-milk Rb, Zn, Cu, and Sr were measured by inductively coupled plasma mass spectrometer. Neurodevelopment was assessed at age 8 months. The primary outcomes were attention and working memory scores, as evaluated by the A-not-B task. Other outcomes included the Mental Development Index (MDI) and Psychomotor Development Index (PDI) as evaluated by the Bayley Scale of Infant Development III. Generalized linear models and restricted cubic spline regression were used to assess the associations between trace elements and neurodevelopment indices. Bonferroni correction was conducted on all data presented.Results: A nonlinear association was observed between breast-milk Rb at 42 days and infant's attention at age 8 months (nonlinearity P = 0.037). Positive associations were observed with infant MDI scores and breast-milk Rb at 42 days (β = 4.46; P = 0.06) and 8 months (β = 3.79; P = 0.009) postpartum. Breast-milk Zn at 42 days was positively associated with infant's attention (β = 0.31; P = 0.039). Sr at 42 days was positively correlated with attention (β = 0.18; P = 0.043) and MDI scores (β = 2.18; P = 0.015) at 8 months. Inverted U-shape associations were observed for breast-milk Cu at 42 days with infant attention and PDI scores. All associations were not significant after correction for multiple tests.Conclusions: Our data suggest that Rb, Zn, Cu, and Sr in breast milk at certain concentrations are associated with neurodevelopment in breastfed infants. Further studies are warranted to validate the findings. [ABSTRACT FROM AUTHOR]

The supporting structure's dynamic stiffness has an important influence on the rotor system. However, current research is mainly limited to the stiffness of a single supporting structure. A single supporting structure may not meet the requirements of the rotor system in some cases. Therefore, the method of solving dynamic stiffness of combined supporting structure is presented and compared with the traditional method based on the parallel stiffness formula. The correctness of the proposed method is verified experimentally. Then, the model of rotor system is established that takes into account the combined supporting structure's dynamic stiffness. Finally, the variation of rotor system's critical speeds and vibration response under the influence of dynamic stiffness is analyzed. An experiment is carried out to verify the influence of dynamic stiffness on the critical speeds. Furthermore, the critical speeds of rotor system will decrease under the influence of dynamic stiffness. • This paper presents a dynamic stiffness model of the combined supporting structure. • The accuracy of the proposed model is validated by experiment. • The rotor system model considering dynamic stiffness is established. • The effect of dynamic stiffness on the rotor system is verified by numerical and experimental studies. [ABSTRACT FROM AUTHOR]

Elastic ring squeeze film damper (ERSFD) is extensively used in industrial rotating systems due to its excellent noise control and vibration suppression characteristics. However, the oil film sealing and leakage has a profound effect on the mechanical and vibration characteristics of the ERSFD and the ERSFD-rotor during operation. The sealing and leakage reduce the axial flow of the oil film, leading to changes in the initial boundary conditions of the flow field, which in turn affects the oil film pressure and damping coefficient of ERSFD. Meanwhile, the sealing causes an increase in the oil film force of ERSFD, which in turn affects the response of the rotor system. But there is relatively little research on the impact of sealing and leakage on the dynamic performances of ERSFD-rotor. In this paper, a mathematical model of ERSFD under different sealing conditions (no end seal, complete end seal, piston ring seal, O-ring seal) is established by changing the initial boundary equations of the flow field of ERSFD and the coupled solution of the Reynolds equation of ERSFD with different sealing and leakage boundary equations is realized. Then, the characteristics of oil film pressure and force of ERSFD under different sealing conditions is studied. After that, an ERSFD-rotor model considering oil film sealing and leakage is established based on displacement compatibility conditions and force balance principles. Meanwhile, the impact of sealing and leakage on the amplitude-frequency relation and sudden imbalance of an ERSFD combined support rotor is researched. The research results reveal that good sealing can significantly increase the damping of the system, thereby reducing the vibration amplitude of the ERSFD-rotor system. In addition, good sealing conditions can also shorten the transient process of sudden unbalanced excitation. Finally, the effectiveness of some simulation results was verified through experiments on the ERSFD rotor test bench. • This paper proposes a model of ERSFD under different sealing conditions by coupling different boundary equations. • The dynamic characteristics of oil film pressure and force of ERSFD under different sealing conditions are analyzed. • The impact of different sealing and leakage conditions on vibration amplitude and damping of ERSFD rotor is analyzed. • Experimental testing for the amplitude frequency response of ERSFD-rotor with no end seal is carried out. [ABSTRACT FROM AUTHOR]

In actual engineering practice of the variable stator vane (VSV) adjustment mechanism, it has been found that the deformation beyond design conditions of the kinematic chain formed from the linkage ring to the blades influences the motion accuracy of the mechanism the most. In this paper, the static stiffness model of the components system, formed from the linkage ring to the blades, is developed and then a motion compensation method based on the stiffness model is proposed. The correctness of the stiffness model is verified by the FEA method. With the model, influence factors such as blade quantity on the stiffness are characterized. In order to investigate the engineering applicability of the stiffness model, the motion compensation model is applied to the dynamic analysis and contrasts with the experimental results of two test benches designed based on the real VSV mechanisms. As a result, the validity of the stiffness model and the value of the proposed method are both well affirmed. • Deformable components are extracted to form the components system. • The components system stiffness is theoretically evaluated. • The concept of motion compensation based on the stiffness model is proposed. • The stiffness model is applied to the dynamic analysis of test rigs. • The proposed model is recognized through experiments. [ABSTRACT FROM AUTHOR]

In this study, β-cyclodextrin (β-CD) molecules are used as molecular reservoirs and grafted onto chitosan molecules for calcitriol (VD3) loading, which is a hormonally active metabolite of vitamin D. The resultant molecular complex is co-assembled with an antiosteoporosis drug calcitonin (CT) to form bio-functional multilayer structure on Ti6Al7Nb substrate via layer-by-layer self-assembly, which is capable of releasing VD3 and calcitonin in a sustained manner to modulate osteoblasts, osteoclasts, and macrophages at the bone-implant interface. In vitro results show that the released VD3 and CT individually upregulated the expression of calcium-binding protein (including Calbindin D9k and Calbindin D28k) and BMP2 in osteoblasts in peri-implant regions to stimulate their Ca deposition and differentiation. RAW264.7 cells (a murine macrophage) on the biofunctional implant displayed improved M2 phenotypical differentiation and expression of BMP2 and VEGF genes, but M1 phenotypical differentiation potential and MCF and TRAP gene expression levels are evidently lower. Results from in vivo micro-CT and histological analysis also demonstrate that VD3/CT co-loaded implant can dramatically enhance the bone remodeling under osteoporotic conditions with significantly enhanced interfacial shear strength and improved osseointegration as compared to other groups. The insights in this study offer new avenues for the rational functionalization of titanium implants to effectively repair osteoporotic fractures. A promising strategy to enhance the recovery rate of osteoporotic fractures is to immobilize antiosteoporotic drugs onto the surface of titanium-based implants. In this study, we grafted beta-cyclodextrin (β-CD) onto chitosan (Chi) molecules to load VD3, which was co-assembled with calcitonin (CT) onto Ti6Al7Nb implants by the layer-by-layer assembly technique. The obtained functional titanium alloy implant (Ti6Al7Nb/LBL/Chi-CD@VD3/ CT) could stably release VD3 and calcitonin agents in a sustained manner. RAW264.7 cells grown on Ti6Al7Nb/LBL/Chi-CD@VD3/CT showed superior M2 phenotypical differentiation efficiency, but lower MCF/TRAP gene expression levels. In vitro and in vivo results showed that the released VD3 and CT individually upregulated the expression of calcium binding proteins and BMP2 in osteoblasts, promoting new bone formation in the peri-implant region. Image, graphical abstract [ABSTRACT FROM AUTHOR]

For the characterization of joint contact model of the variable stator vane (VSV) mechanism, the dry friction properties of joint materials must be taken into account. In this paper, the important parameters characterizing the joint contact model are experimentally tested, and then the characterized contact model containing the parameters is utilized for the dynamic analysis of a principle-level VSV mechanism test rig, including the dry friction rotary pair. Firstly, the friction tests and the vibration tests induced by the friction process are carried out. Then an ideal comprehensive dynamic model of the scaled system of VSV mechanism's single kinematic chain is established through the Lagrange multiplier method. The friction coefficient values obtained from the test are embedded into the contact force model considering friction factors and compared with other macro models. The accuracy of the hybrid contact model is verified through a one-shot contact-impact simulation and the corresponding displacement is measured for evaluation with accuracy of established ideal dynamic model. Finally, the influence of different driving methods on the dynamic characteristics of the system is analyzed. • Characterization of joint contact model considering friction based on experiment. • Dynamic model of scaled VSV mechanism is established. • Application joint contact model to dynamic analysis of scale mechanism. [ABSTRACT FROM AUTHOR]

Highlights • A kind of dynamic parametrical model is identified for the analysis and design on nonlinear systems. • An improved Extended Forward Orthogonal Regression algorithm is proposed to promote the efficiency in computation. • The proposed algorithm can circumvent the overfitting problem. • An iterative design that produces a sequence of suboptimal models is applied in the modeling process. Abstract In this study, the identification of a Nonlinear Auto-Regressive with exogenous inputs (NARX) model of nonlinear systems, where the physical parameters of interest for the system design appear explicitly as coefficients in the model, is studied. The model is a dynamic parametrical model, referred as the NARX model with parameters of interest for design (NARX-M-for-D). An improved algorithm, known as the Iterative Extended Forward Orthogonal Regression (IEFOR), is proposed to identify the NARX-M-for-D of nonlinear systems. Firstly, a common-structured model, referred to as the “initial model”, is established through the traditional Extended Forward Orthogonal Regression (EFOR) algorithm. Then an iterative process is applied to revise the initial model such to produce an improved model of the system, which is referred to as the “common model” in this study. Finally, functional relationships of the common model coefficients are established to determine the NARX-M-for-D of the system. Both the simulation and experimental studies are discussed to illustrate the application of the new algorithm. The results indicate that, by using the IEFOR algorithm, the established model can accurately predict the system out response and remain the merit of efficiency in computation. The new algorithm is expected to be applied in the identification of nonlinear systems in engineering practice. [ABSTRACT FROM AUTHOR]

The Variable Stator Vane (VSV) mechanism is utilized to adjust the stator vane angles so as to delay the compressor stall. Establishing the dynamic model of the system, which is the basis to obtain different joint characteristics more in line with the real case, is worth analyzing. In this work, a comprehensive dynamic model of the scaled system of VSV mechanism's single kinematic chain by the Lagrange multiplier method is built, thus the spatial plane joint characteristic's effects on the behavior of the scaled system are investigated. Since a full-scale facility is unavailable for testing sometimes, the technique of similarity scaling is resorted to establishing the scaled principle-level model which has a certain relationship with the prototype in structure and material and so on. Then an example of the dynamic modeling procedure of the spatial RSSR mechanism included in the scaled model is presented with the aim of establishing a guide to model the whole system. Therefore, the equation of motion of the scale system is expediently established using some systematic method. Finally, inertial navigation sensors are used to measure the corresponding displacement for evaluation with accuracy of the established dynamic model. • Principle-level test rig design based on so-called similitude theory. • Dynamic model of scaled VSV mechanism is established. • The conformal contact model is applied, closer to the actual contact situation. • The rotation angle is measured using the inertial navigation system. • The rotation matrix of the rigid body based on the rotation axis vector is explained. [ABSTRACT FROM AUTHOR]

To efficiently deliver anti-cancer drug to tumor site and reduce its toxic side effects on normal tissues, a polyethylene glycol (PEG) shielding and tumor microenvironment triggering cascade pH-responsive hollow mesoporous silica nanoparticles (HMSNs) drug delivery system was fabricated. 3-(3, 4-dihydroxyphenyl) propionic acid (DHPA) functionalized beta-cyclodextrin (β-CD) was grafted onto the surfaces of HMSNs via boronic acid-catechol ester bonds. Then, PEG conjugated adamantane (Ada) was anchored on HMSNs-β-CD nanocarrier via host-gust interaction. Various techniques proved the successful fabrication of the system. The in vitro tests confirmed that the system was biocompatible. After the system permeating into tumor via enhanced permeability and retention (EPR) effect, the benzoic-imine bonds between the PEG and Ada were cleaved under weak acid condition in tumor microenvironment (pH 6.8), while the dissociated PEG protective layer facilitating cellular uptake of HMSNs system. Subsequently, the boronic acid-catechol ester bonds linkers further hydrolyzed under even low endosomal pH (4.5–6.5) condition for intracellular drug delivery, leading to efficient cell apoptosis. The in vivo results demonstrated that drug loaded HMSNs significantly inhibited tumor growth while only with minimal toxic side effects. The strategy provides new insight into the development of new generation of drug delivery carriers triggering by tumor microenvironment. [ABSTRACT FROM AUTHOR]

Building insulation materials have a significant effect on the reduction of heating/cooling energy consumptions of buildings. From a life cycle perspective, the comparison of different types of insulation materials should consider the building energy consumption together with the environmental emissions during the manufacturing, production, transportation, using and recycling phases of insulation materials. However, this comparison suffers from many sources of uncertainty, especially the parameter identification of insulation materials. In this study, a life cycle inventory analysis model is established and applied to compare the life cycle performance of eight types of insulation materials in an uncertain framework. For each parameter, a probability density function is explicitly specified through a parameter identification process, and the data uncertainty is propagated by Monte-Carlo simulation, the inventory analysis results are transformed from a concrete value into a probability distribution around a mean value, and sensitivity analysis is implemented to identify uncertainty and variability affecting produced the life cycle assessment (LCA). The simulation results revealed that physical parameters have a significant contribution to the uncertainty of the insulation materials, especially for life cycle energy consumption of glass wool, the maximum value may even be quadrupled compares to the minimum value. The decision maker may change the choice of insulation materials when data uncertainty is taken into consideration in LCA. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a type of intracellular redox-triggered hollow mesoporous silica nanoreservoirs (HMSNs) with tumor specificity was developed in order to deliver anticancer drug (i.e., doxorubicin (DOX)) to the target tumor cells with high therapeutic efficiency and reduced side effects. Firstly, adamantanamine was grafted onto the orifices of HMSNs using a redox-cleavable disulfide bond as an intermediate linker. Subsequently, a synthetic functional molecule, lactobionic acid-grafted-β-cyclodextrin (β-CD-LA), was immobilized on the surface of HMSNs through specific complexation with the adamantyl group, where β-CD served as an end-capper to keep the loaded drug within HMSNs. β-CD-LA on HMSNs could also act as a targeting agent towards tumor cells (i.e., HepG2 cells), since the lactose group in β-CD-LA is a specific ligand binding with the asialoglycoprotein receptor (ASGP-R) on HepG2 cells. In vitro studies demonstrated that DOX-loaded nanoreservoirs could be selectively endocytosed by HepG2 cells, releasing therapeutic DOX into cytoplasm and efficiently inducing the apoptosis and cell death. In vivo investigations further confirmed that DOX-loaded nanoreservoirs could permeate into the tumor sites and actively interact with tumor cells, which inhibited the tumor growth with the minimized side effect. On the whole, this drug delivery system exhibits a great potential as an efficient carrier for targeted tumor therapy in vitro and in vivo. [Copyright &y& Elsevier]

Abstract: This study investigates the hydrodynamic and thermal performance of nanofluids in the region of thermal developing laminar mixed convection. Single-phase approach was employed to evaluate the pumping power and heat transfer coefficient, i.e., no novel mechanism other than the renewing thermophysical properties of nanofluids was involved. An aggregation-mechanism-based methodology was introduced and verified to well unify the rheological and thermal properties of nanofluids. In comparing the pumping power savings, critical differences between forced convection and mixed convection were found: nanofluids are more favorable for application to mixed convection. Criteria for nanofluid forced-mixed transition have been discussed and presented to help the decision of whether a flow can be viewed as mixed flow. [Copyright &y& Elsevier]

Abstract: The extracellular microenvironment plays a key role in the regulation of cellular behavior. To mimic the natural extracellular microenvironment, TiO2 nanotube (TNT) arrays as drug nanoreservoirs for loading of bone morphogenetic protein 2 (BMP2) were constructed on titanium substrates and then covered with multilayered coatings of gelatin/chitosan (Gel/Chi) for controlled drug release. The multilayered coatings were constructed via a spin-assisted layer-by-layer assembly technique. The successful fabrication of this system was monitored by field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and contact angle measurements. Multilayered coating with Gel/Chi retained the drug bioactivity and release properties, which were revealed by superoxide dismutase activity measurement. In addition, cytoskeleton observation and wound healing assay confirmed that BMP2-loaded and multilayer-coated TNT arrays were able to stimulate motogenic responses of mesenchymal stem cells (MSCs). More importantly, the system demonstrated that it was capable of promoting the osteoblastic differentiation of MSCs. This study may have potential impact on the development of bone implants for enhanced bone osseointegration. [Copyright &y& Elsevier]

• This paper proposes a method to obtain scaling laws for rotor systems. • This paper proposes frequency adjustment laws for predicting responses in non-resonant state. • The proposed method provides several scaling laws in whole range of rotating speed. • Experimental testing for vibration responses of prototype and model is carried out. • The proposed method can improve prediction accuracy compared with existing methods. Similitude theory provides the necessary conditions to predict the structural responses of the full-scale prototype through the scaled model, and is widely used in full-scale experiments of large structures. However, the prediction accuracy is insufficient in partial similitude. Aiming at this issue, this paper proposes the frequency adjustment laws to predict vibration responses of full-scale rotor in non-resonant state, since the rotating machinery usually works in non-resonant state. On this basis, a partial similitude method is presented by combining the frequency adjustment laws with the current method. The proposed method provides several scaling laws in the whole range of rotating speed, while only one scaling factor is used to predict the vibration responses in existing methods. The accuracy of the proposed method is verified by the numerical and experimental case studies, where the geometrical distortion is considered. In the numerical case study, the scaling laws of a rotor system are obtained by the proposed method and existing methods. The predicted results of the proposed method are compared with those of the existing methods. It is found the proposed method accurately predicts the displacements and accelerations of prototypes through those of scaled model. Moreover, the proposed method achieves a higher accuracy. The experimental study carries out the testing for the prototype and model test rigs. The experimental results show that the proposed method provides better results in predicting the displacement and acceleration compared with the existing methods. The proposed method allows designers to design a scaled model and to reproduce the vibratory behavior of the full-size prototype, which reduces the difficulty, costs and time of experimental test. Moreover, the proposed partial similitude method has a better performance than the existing methods. [Display omitted] [ABSTRACT FROM AUTHOR]

• The scaling laws obtained by the proposed method consider the variable powers and coupling effect among the scaling factors. • The proposed method improves the accuracy for predicting the responses of rotor-bearing system. • The scaling laws for vibration responses of rotor-bearing systems in partial similitude are developed for the first time. • The proposed method can work without the governing equation or its solution of a structure. Similitude theory is used to establish the necessary conditions between the enlarged or reduced model and the original structure, and has been widely applied to vibration and impact tests of large structures. However, several limitations and difficulties still persist in partial similitude for complex structures. In this paper, a partial similitude method to obtain scaling laws is proposed. The powers in scaling laws are variables against the scaling factors, and the coupling effect among design parameters is considered in the powers. The accuracy and applicability of the proposed method are demonstrated in two case studies. The first case study discusses the partial similitude of a single rotor-bearing system. The single rotor-bearing system is scaled with distortion in the geometrical dimension and boundary conditions. It is found that the proposed method predicts the critical speeds and unbalance responses with good accuracy. Furthermore, the proposed method can improve the prediction accuracy by comparing with the methods in current literatures. The second case study comprises a dual-rotor system to demonstrate the accuracy and applicability of the proposed method for more complex rotor-bearing system. The speed ratio, excitation position, co-rotation, and counter-rotation are discussed in predicting the critical speeds as well as unbalance responses. It is also found that the proposed method can improve the prediction accuracy. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this study, a novel variable-stiffness structure (VSS) featuring temperature-dependent characteristics is introduced for the optical payload of the Jilin1-GF04X satellite, which has an image resolution of 0.3 m. The VSS, constructed from polyurethane material, was engineered to operate at room temperature (22 °C) during the rocket launch phase in order to withstand adverse dynamic conditions. Additionally, the structure was designed to function at a higher temperature (35 °C) while in orbit to improve the efficiency of microvibration isolation. The assessment of the suppression capabilities of the presented vibration isolator, as compared to the present carbon fiber structure, was conducted through an integrated analysis. Ground-based microvibration tests were subsequently carried out to evaluate the capacity of the VSS for adjusting its stiffness and damping properties. The results showed that the maximum amplitude of pixel offset reduced by 27.6% at 35 °C compared to 22 °C, confirming the efficacy of the structure. • A variable-stiffness structure (VSS) featuring temperature-dependent characteristics is proposed. • The dynamic properties of polyurethane materials are characterized using the fractional derivative constitutive equation. • The integrated model is established by the optical model, structural model, control model of the satellite and the perturbations of the flywheel. • Ground-based microvibration tests are carried out to evaluate the capacity of the VSS for adjusting its stiffness and damping properties. [ABSTRACT FROM AUTHOR]

• A dynamic model is proposed to solve the vibration response of an L-shaped pipeline under base harmonic and random excitations. • The proposed model is verified by comparing the natural frequencies and mode shapes of experiments. • The vibration response of L-shaped pipeline under random excitation is tested and compared by simulation. The aero-engine pipeline is inevitably subjected to base harmonic and random excitations during operation, but the vibration response analysis of the aero-engine pipeline under base random excitation has been rarely incorporated in the open research. Therefore, a dynamic model of an L-shaped pipeline combining the transfer matrix method (TMM) and lumped parameter method is proposed to solve the vibration response of the aero-engine pipeline under base harmonic and random excitations, and the natural and response characteristics of the pipeline are investigated by simulation and experiment. Firstly, the transfer matrix of the L-shaped pipeline is derived, and the natural frequencies and the corresponding mode shape vectors are obtained. Then, combined with the lumped parameter method, the transfer matrix of the L-shaped pipeline under base harmonic excitation is reconstructed and its frequency domain response is solved. On this basis, the virtual excitation method is introduced to address the dynamic responses of pipelines under base random excitation. Finally, the vibration test system for the L-shaped pipeline subjected to base excitation is built, and the vibration response solution method is verified through the comparison of simulation and experimental results. The work can provide an effective solution for the vibration response analysis of aero-engine pipelines under base harmonic and random excitations. [ABSTRACT FROM AUTHOR]

• The dynamic model of the two-span rotor-bearing-pedestal system is established. • A fault characterization model of raceway extension defects is proposed. • The influence of misalignment on bearing defect fault is further discussed. • The system dynamic characteristics during bearing defect extension are analyzed. When the rolling bearing raceway is tilted, the contact load of the raceway increases, which may greatly increase the occurrence of raceway defects. However, the evolution law of the raceway defect extension process on the system dynamic characteristics is not clear when the bearing is tilted. In this paper, considering the influence of rough surface caused by the extension of bearing defects, a mathematical model of raceway extension defects which is more consistent with the actual morphology is proposed. The model can be used to evaluate the damage degree of the bearing raceway of rotating machinery. Taking the two-span rotor-bearing-pedestal system of the test rig as the research object, a nonlinear dynamic model of the system is established considering the nonlinear supporting force of bearings and pedestal, shaft coupling looseness and other nonlinear factors. The effectiveness of the bearing fault characterization model and the system dynamics model is verified by experiments. On this basis, the influence of tilt on bearing fault and the change rule of raceway defect extension on bearing contact characteristics and system dynamic characteristics are discussed. The results indicate that raceway tilt aggravates system vibration caused by the bearing defect. With the increase of the defect range, the impact vibration characteristics weaken, and the roughness of the raceway surface in the defect area has a great influence. However, with the increase of defect depth, the influence law is just the opposite. The research results are expected to provide theoretical support for bearing fault diagnosis of rotating machinery systems. [ABSTRACT FROM AUTHOR]

Oxidative stress is commonly existed in bone degenerative disease (osteoarthritis, osteoporosis etc .) and some antioxidants had great potential to enhance osteogenesis. In this study, we aim to investigate the anti-oxidative properties of various TiO 2 nanotubes (TNTs) so to screen the desirable size for improved osteogenesis and reveal the underlying molecular mechanism in vitro . Comparing cellular behaviors under normal and oxidative stress conditions, an interesting conclusion was obtained. In normal microenvironment, small TNTs were beneficial for adhesion and proliferation of osteoblasts, but large TNTs greatly increased osteogenic differentiation. However, after H 2 O 2 (300 μM) treatment (mimicking oxidative stress), only large TNTs samples demonstrated superior cellular behaviors of increased osteoblasts' adhesion, survival and differentiation when comparing with those of native titanium (control). Molecular results revealed that oxidative stress resistance of large nanotubes was closely related to the high expression of integrin α5β1 (ITG α5β1), which further up-regulated the production of anti-apoptotic proteins (p-FAK, p-Akt, p-FoxO3a and Bcl2) and down-regulated the expression of pro-apoptotic protein (Bax). Moreover, we found that Wnt signals (Wnt3a, Wnt5a, Lrp5, Lrp6 and β-catenin) played an important role in promoting osteogenic differentiation of osteoblasts under oxidative condition. [ABSTRACT FROM AUTHOR]

This study aims to investigate the nonlinear vibration properties of a rotor-bearing system carrying a multi-disk bolted joint with a fixed-point rubbing fault. For this purpose, a mathematical model of a multi-disk bolted joint rotor system is explored to determine the effect of rotor-stator rub-impact and rub-impact positions on the nonlinear dynamics of a certain type of aero-engine compressor. First, the dynamics of the rotor system with a rubbing fault are examined numerically. Then, the effect of the rub-impact position in the multi-disk bolted joint on the nonlinear dynamics is studied. The shaft is modeled using a massless shaft, where the stiffness matrix of the shaft is determined based on the flexibility influence coefficient method. The governing equation of the multi-disk bolted joint is deduced considering both the lateral and bending stiffness between the adjacent disks. The dynamic model of the overall system can then be obtained by combining the shaft and multi-disk bolted joint. The resultant governing equations of motion are solved using direct numerical integration. The numerical results obtained from the established model are compared with those of a similar structure in other literature to verify the accuracy of the method used in this study. Then, the dynamic behavior of the rotor system and the mechanical properties of the multi-disk bolted joint under a rubbing fault are presented. Finally, the chaotic response with the rub-impact force acting on different positions of the multi-disk bolted joint is investigated through numerical simulations. • A unified approach for modeling of the multi-disk bolted joint rotor system is proposed. • Mechanical properties of multi-disk bolted joint under rubbing fault are evaluated. • Dynamic properties of the multi-disk bolted joint rotor system with rubbing fault are studied. • Effect of rubbing position in the multi-disk bolted joint on rotor dynamics was demonstrated. [ABSTRACT FROM AUTHOR]

Over the past decades, black phosphorus (BP) emerges as an effective photothermal material with clinically favorable biocompatibility and biodegradation that receives broad attention for tissue engineering. BP nanosheets with tunable sizes and morphologies could be exfoliated from bulk BP via top-bottom or bottom-up methods, thus endowing versatile photothermal performance. Due to its intrinsic degradability in the presence of oxygen and water, various surface modifications are usually warranted to enhance the biostability of BP in physiological environment during bone repair. Compared with traditional bone implant materials, BP-based materials not only enable high selective and efficient photothermal therapy (PTT) that can stimulate bone regeneration via up-regulating expression levels of heat shock proteins (HSPs), but also generate abundant phosphate to support the mineralization of extracellular matrix and promote new bone formation after near-infrared (NIR) irradiation treatment. Inspired by the immense application potential of BP-based biomaterials for bone-related engineering, here we provide a comprehensive analysis regarding the surface modification methods of BP, BP-mediated biological mechanisms to trigger osteogenic differentiation, and BP-induced biomineralization for promoting bone formation. This review may inspire more successful explorations for BP-mediated bone repair in the future. [ABSTRACT FROM AUTHOR]

This study reports a reactive oxygen species (ROS) sensitive drug delivery system based on amphiphilic polymer of poly(propylene sulfide)-polyethylene glycol-serine-folic acid (PPS-mPEG-Ser-FA). The polymer could form homogeneous micelles with an average diameter of around 80 nm through self-assembly, which would then be loaded with the singlet oxygen-generating photosensitizer of zinc phthalocyanine (ZNPC) and anti-cancer drug of DOX. The disassembly of micelles could be triggered by the hydrophobic to hydrophilic transition of the PPS core in response to ROS-induced oxidation in vitro . ZNPC molecules are capable of producing ROS under laser irradiation, which results in the rapid disassembly of micelles and releasing of the anti-tumor drug for tumor therapy under physiological condition otherwise. Moreover, the excessive ROS production deriving from ZNPC synergically induces cells apoptosis. Furthermore, the DOX loaded amphiphilic micelles could be internalized by tumor cells via FA receptor-mediated endocytosis to effectively inhibit the tumor growth in vivo , while with only minimal toxic side effects. The results in vitro and in vivo consistently demonstrate that the light-responsive micelle is a promising biodegradable nanocarrier for on-command drug release and targeted tumor therapy. [ABSTRACT FROM AUTHOR]