Search

In this paper, we theoretically investigate the nonlinear dynamic characteristics of a gear pair system with dynamic backlash subjected to internal and external periodic excitations. The dynamic model of a viscously damped single degree of freedom gear pair model with periodic time-varying stiffness, dynamic backlash, static transmission error and external periodic excitation is established. The incremental harmonic balance method (IHBM) is applied to analyze the frequency response characteristics as well as the effects of dynamic backlash, time-varying stiffness, excitation force amplitude and damping ratio on the dynamic characteristics of the gear pair system. The analysis results are compared with the numerical integration results to show accuracy and authority of the IHBM. The difference between the constant backlash and the dynamic backlash models is also discussed. The results show that the nonlinear dynamic characteristics such as parametric resonance, multi-valued properties and jump phenomena are strongly attributed to the interaction between time-varying stiffness and backlash. Significantly, under combined internal and external periodic excitations, the multi-valued properties and jump phenomena occur not only in primary resonance frequency but also in super harmonic frequency. The increase of the dynamic backlash and damping ratio could effectively control the nonlinear vibration of gear system; whereas the excitation force amplitude has less influence on the nonlinear dynamic characteristics and the increase of the excitation force amplitude could no longer control the nonlinear vibration of gear system, which is different from the dynamic characteristics under internal periodic excitations. [ABSTRACT FROM AUTHOR]

A proof of concept on-/off- keying (OOK) modulator is designed and implemented in a commercial heterojunction bipolar transistors IC process. The modulator circuit consists of an amplifier/latch structure, which is used as an OOK modulator for the first time. One of its advantages is that the topology may be implemented in both field effect transistor and bipolar technology. The measurement results correspond well with simulation and show that the modulator is capable of handling carrier frequencies up to 28 GHz, and data rates up to 14 Gbps. The isolation of the modulator in the off-state is better than 27 dB over the whole frequency range. [ABSTRACT FROM PUBLISHER]

[Display omitted] • DTPP suppresses LPS-induced inflammation by interfering with the TLR4/MD-2 signaling pathway. • DTPP alleviates ER stress and inflammation both in vitro and in vivo. • DTPP alleviates macrophage infiltration and mitigates hepatocellular lipid accumulation in the steatotic liver of zebrafish. Non-alcoholic fatty liver disease (NAFLD) is a complex pathogenic metabolic syndrome characterized by increased inflammation and endoplasmic reticulum stress. In recent years, natural polysaccharides derived from traditional Chinese medicine have shown significant anti-inflammatory effects, making them an attractive therapeutic option. However, little research has been conducted on the therapeutic potential of dried tangerine peel polysaccharide (DTPP) — one of the most important medicinal resources in China. The results of the present study showed that DTPP substantially reduced macrophage infiltration in vivo and suppressed the expression of pro-inflammatory factors and endoplasmic reticulum stress-related genes. Additionally, surface plasmon resonance analysis revealed that DTPP had a specific affinity to myeloid differentiation factor 2, which consequently suppressed lipopolysaccharide-induced inflammation via interaction with the toll-like receptor 4 signaling pathway. This study provides a potential molecular mechanism underlying the anti-inflammatory effects of DTPP on NAFLD and suggests DTPP as a promising therapeutic strategy for NAFLD treatment. [ABSTRACT FROM AUTHOR]

Engineering structures in marine and vehicle are frequently subjected to repeated impact loadings. The damage can’t be neglected during the accumulation of deflection caused by the repeated impacts. In this paper, the dynamic behaviour of aluminum foam sandwich plate (AFSP) under repeated impacts was investigated by impact tests using INSTRON 9350 Drop Tower. The penetration behavior of front face and back face are compared. Meanwhile, the relationships between deflections of face sheets with impact number as well as the loading-unloading process during repeated impacts are analyzed. Results showed that, the permanent deflections of the front face and back face increased gradually, while the increments decreased until the crack occurred on the front face sheet. The damage modes of front face and back face were different. The impact number (N p ) for penetration of front fact and residual number (N r ) for perforation of back face both decreased in exponential form with the increase of impact energy. It implied that the back face sheet still has residual load-carrying capacity even if the front face sheet became cracked. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic behaviour of aluminium foam sandwich plates (AFSPs) under impact loadings at low temperature was experimentally investigated. The impact force and the deformation as well as the energy absorption performances of AFSPs at room temperature and low temperature were obtained by using the drop tower INSTRON 9350 with thermostatic test chamber. The effects of impact energies and repeated impact loadings on the dynamic behaviour of AFSPs at room temperature (20 °C) and low temperature (−60 °C) were further examined. Experimental results showed that with the increase of the impact energy, the effect of low temperature on the dynamic behaviour of AFSPs under single impact loadings was enhanced gradually, the deflections of AFSPs at low temperature were smaller compared to that at room temperature, as a result of the increase in the yield stress of aluminum foam and mild steel at low temperature. Under repeated impact loadings, the deflections and absorbed energies of AFSPs at low temperature were smaller than those at room temperature. With the increase of impact number, the effect of low temperature on dynamic behaviour of AFSPs became much more significant. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic responses and energy dissipation characteristics of polyvinyl chloride (PVC) foam core sandwich plates under ice impact are investigated. The ice impact tests of PVC foam core sandwich plates were conducted by employing the horizontal impact experimental apparatus. The finite element simulations were conducted to analyze the dynamic response of PVC foam core sandwich plates based on soil and concrete material model for ice impactor. It was demonstrated that numerical results were in good agreement with experimental results. The deformation modes of the top facesheets were coupling of local indentation with global bending deformation, while the deformation modes of bottom facesheets were overall bending deformation. The permanent deformation of face sheets show that the impact resistance of sandwich plate is better than that of equivalent weight hull plate (EWHP). In addition, based on the actual navigation environment of ship, the effect of impact angle and ice floe shape on dynamic response and energy dissipation are analyzed. • The ice impact responses and energy dissipation characteristics of PVC FCSPs are investigated. • The ice impact tests were conducted. • A three-dimensional nonlinear finite element model is established. • The effect of impact angle and ice floe shape on dynamic response are analyzed. [ABSTRACT FROM AUTHOR]

• DTPP enhances macrophage infiltration within the wound area in zebrafish. • DTPP induces alternative activation of mice macrophages in vitro and in vivo. • DTPP exhibits promising potential as a wound-healing accelerator for both nonmammal vertebrates and mammals. Macrophage polarization is a key process involved in wound healing. The continuous release of proinflammatory cytokines by macrophages inhibits the healing process of chronic wounds, such as diabetic wounds. To promote wound healing, it is important to change the phenotype of resident macrophages to prevent inflammation. We previously reported that dried tangerine peel polysaccharide (DTPP) binds to and inhibits the TLR4/MD-2 complex, which is crucial for the inflammatory activation of macrophages, suggesting the potential of DTPP in wound healing applications. Both zebrafish and mouse models were used to evaluate the therapeutic efficacy of DTPP. Moreover, we found that DTPP recruited macrophages to the wound area and promoted their M2 repolarization. Using hyperglycaemic zebrafish and db/db mouse models, we discovered that DTPP accelerated wound healing in vivo in metabolic disorders. Our results suggest that DTPP promotes the recruitment of macrophages, shifts macrophages towards the anti-inflammatory M2 phenotype, and ultimately accelerates the wound healing process. [ABSTRACT FROM AUTHOR]

Elastic metamaterial is a type of artificial composite material/structure with unique subwavelength physics property, which shows attractive potential application in low-frequency sound and vibration control. In this paper, a ship vibration isolation method using the band gap concept of sandwich plate-type elastic metastructures is proposed to solve the low frequency vibration and noise control of marine power system. The flexural wave propagation and low-frequency vibration isolation characteristics of sandwich plate-type elastic metamaterials are investigated by using the finite element method combination with Solid-Shell multi-physics coupling model and Bloch theory. Numerical results demonstrate that the proposed sandwich plate-type elastic metastructures possess significant low-frequency subwavelength flexural wave band-gap and vibration isolation characteristics under the premise of structural strength and stiffness. The formation mechanism of flexural band gap is mainly attributed to the mode coupling of the local resonant mode and the Lamb wave mode of sandwich plate. The experimental measurements of flexural vibration transmission spectra were conducted to validate the accuracy and reliability of the numerical calculation method. In addition, the influences of geometrical parameters on the flexural wave band gap are studied. On this basis, the potential application of the proposed ship vibration isolation method in the marine power system is explored. • A ship vibration isolation method using the band gap concept is proposed. • The dispersion relations are calculated by using Solid-Shell multi-physics coupling model. • The experimental measurements of flexural vibration transmission spectra were conducted. • The potential application of ship vibration isolation method in the marine power system is explored. [ABSTRACT FROM AUTHOR]

This paper presents a novel micromachining process to fabricate a 140 GHz planar antenna based on gap waveguide technology to be used in the next-generation backhauling links. The 140 GHz planar array antenna consists of three layers, all of which have been fabricated using polymer-based microfabrication and injection molding. The 140 GHz antenna has the potential to be used as an element in a bigger 3D array in a line-of-sight (LOS) multiple input multiple output (MIMO) configuration to boost the network capacity. In this work, we focus on the fabrication of a single antenna array element based on gap waveguide technology. Depending on the complexity of each antenna layer's design, three different micromachining techniques, SU8 fabrication, polydimethylsiloxane (PDMS) molding, and injection molding of the polymer (OSTEMER), together with gold (Au) coating, have been utilized to fabricate a single 140 GHz planar array antenna. The input reflection coefficient was measured to be below − 11 dB over a 14% bandwidth from 132 to 152 GHz, and the antenna gain was measured to be 31 dBi at 140 GHz, both of which are in good agreement with the simulations. [ABSTRACT FROM AUTHOR]

Repeated mass impact loadings often occur in the marine engineering field, such as ship collisions, aircraft landing impacts, ice impacts, and some falling object impacts. For metal structure components subjected to repeated mass impacts, a great deal of experimental, numerical and theoretical studies has been conducted in the past thirty years. This paper has reviewed and summarized the mechanical mechanisms of structures under repeated mass impacts, especially for repeated rigid mass impacts and repeated ice impacts. Besides, some significant influencing factors on structural responses under repeated mass impacts are discussed, such as indenter types, material elasticity, strain hardening effect and low temperature. Furthermore, with the development of new composite material technology, several novel composite structures applied for resisting repeated mass impacts are introduced in the paper. The accumulated damage mechanisms and energy absorption characteristics of these composite structures are reviewed. The review of this paper can contribute to the protective structure design in resisting repeated mass impact loadings. • The recent research progress for metal structure components subjected to repeated mass impacts is systematically reviewed. • The mechanical mechanisms of structures under repeated mass impacts by rigid and deformable bodies are concluded. • Some influencing factors on structural responses under repeated mass impacts are discussed. • Plastic design examples for metal structures subjected to repeated rigid mass impacts are presented. • The accumulated damage mechanismsof some novel composite structures under repeated mass impacts are summarized. [ABSTRACT FROM AUTHOR]

The advent of immune checkpoint inhibitors ushers in a new era of anti-tumor immunity. However, current clinical anti-PD-L1 antibodies only interdict PD-L1 on the membrane, which cannot diminish the complex cancer-promoting effects of intracellular PD-L1. Therefore, directly reducing the PD-L1 abundance of cancer cells might be a potential PD-L1 inhibitory strategy to circumvent the issues of current anti-PD-L1 antibodies. Herein, we develop a dendritic polymer-functionalized nanomedicine with a potent cellular energy depletion effect on colon cancer cells. Treatment with the nanomedicine significantly promotes phosphorylation of AMPK, which in turn leads to PD-L1 degradation and eventual T cell activation. Meanwhile, the nanomedicine can potently induce immunogenic cell death (ICD) to enhance the anti-cancer immunity. Moreover, the combination of the nanomedicine with PD-1 blockade further enhances the activity of cytotoxic T lymphocytes, and dramatically inhibits tumor growth in vivo without distinct side effects. Overall, this study provides a promising nanoplatform to induce lethal energy crisis and ICD, and suppress PD-L1 expression, thus potentiating cancer immunotherapy. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical behavior of aluminum foam sandwich plate (AFSP) subjected to repeated impact loadings is investigated. Firstly, the method to achieve repeated impacts of AFSP in the numerical simulation is proposed. Then dynamic responses obtained from repeated impact tests are compared with those of numerical simulations, and the results show good agreements. Besides, the mechanism of energy absorption of the AFSP under repeated impacts are examined. Results show that the elastic deformation energy of AFSP increases with the impact number, but the increment declines. On the contrary, the plastic deformation energy decreases with the impact number. In addition, the effects of thickness distribution of face sheets on impact resistance of AFSP under repeated impacts are investigated. It can be found that as the thickness of front face sheet increases, the peak impact force and the energy absorbed by front face sheet increase, while the deflections of front and back face sheets, the energy absorbed by back face and aluminum foam decrease. [ABSTRACT FROM AUTHOR]

Increasing evidence indicates that immunotherapy is hindered by a hostile tumor microenvironment (TME) featured with deprivation of critical nutrients and pooling of immunosuppressive metabolites. Tumor cells and immunosuppressive cells outcompete immune effector cells for essential nutrients. Meanwhile, a wide range of tumor cell-derived toxic metabolites exerts negative impacts on anti-tumor immune response, diminishing the efficacy of immunotherapy. Nanomedicine with excellent targetability offers a novel approach to improving cancer immunotherapy via metabolically reprogramming the immunosuppressive TME. Herein, we review recent strategies of enhancing immunotherapeutic effects through rewiring tumor metabolism via nanomedicine. Attention is drawn on immunometabolic tactics for immune cells and stromal cells in the TME via nanomedicine. Additionally, we discuss future directions of developing metabolism-regulating nanomedicine for precise and efficacious cancer immunotherapy., Competing Interests: Declaration of interests The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Cancer cells could be eradicated by promoting generation of excessive intracellular reactive oxygen species (ROS) via emerging nanomedicines. However, tumor heterogeneity and poor penetration of nanomedicines often lead to diverse levels of ROS production in the tumor site, and ROS at a low level promote tumor cell growth, thus diminishing the therapeutic effect of these nanomedicines. Herein, we construct an amphiphilic and block polymer-dendron conjugate-derived nanomedicine (Lap@pOEGMA-b-p(GFLG-Dendron-Ppa), GFLG-DP/Lap NPs) that incorporates a photosensitizer, Pyropheophorbide a (Ppa), for ROS therapy and Lapatinib (Lap) for molecular targeted therapy. Lap, an epidermal growth factor receptor (EGFR) inhibitor that plays a role in inhibiting cell growth and proliferation, is hypothesized to synergize with ROS therapy for effectively killing cancer cells. Our results suggest that the enzyme-sensitive polymeric conjugate, pOEGMA-b-p(GFLG-Dendron-Ppa) (GFLG-DP), releases in response to cathepsin B (CTSB) after entering the tumor tissue. Dendritic-Ppa has a strong adsorption capacity to tumor cell membranes, which promotes efficient penetration and long-term retention. Lap can also be efficiently delivered to internal tumor cells to play its role due to the increased vesicle activity. Laser irradiation of Ppa-containing tumor cells results in production of intracellular ROS that is sufficient for inducing cell apoptosis. Meanwhile, Lap efficiently inhibits proliferation of remaining viable cells even in deep tumor regions, thus generating a significant synergistic anti-tumor therapeutic effect. This novel strategy can be extended to the development of efficient membrane lipid-based therapies to effectively combat tumors., Competing Interests: The authors declare that they have no known conflicts of Interest/competing interests, competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Nanoprobes that offer both fluorescence imaging (FI) and magnetic resonance imaging (MRI) can provide supplementary information and hold synergistic advantages. However, synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups, high stability, great biocompatibility and desired dual-modality imaging results remains challenging. In this study, we used an amphiphilic block polymer from (ethylene glycol) methyl ether methacrylate (OEGMA) and N -(2-hydroxypropyl) methacrylamide (HPMA) derivatives as a carrier to conjugate a MR contrast agent, Gd-DOTA, and a two-photon fluorophore with an aggregation-induced emission (AIE) effect, TPBP, to construct a MR/two-photon fluorescence dual-modality contrast agent, Gd-DOTA-TPBP. Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r 1 value for Gd-DOTA-TPBP, revealing a great MR imaging resolution. The contrast agent specifically accumulated in the tumor region, allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging. Meanwhile, coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity, but also significantly enhanced its imaging performance in an aqueous phase. Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI. Since high-resolution, complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP, it has great potential in the early phase of disease diagnosis., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

The synthesis of efficient porphyrin-based photosensitizers with intense near-infrared (NIR) absorption is in high demand for photodynamic therapy (PDT) but remains a challenging task. Herein we show the construction of a type of isoquinoline-fused porphyrins 3 and 4 with an impressive NIR-absorbing capacity. In light of the extraordinary singlet oxygen generation capabilities of 3 upon NIR irradiation, the representative nanoparticles ( 3a-NPs ) assembled show excellent tumoricidal behavior with good biocompatibility in the phototherapeutic window (650-850 nm).

In this paper, we numerically and experimentally demonstrate the low-frequency broadband elastic wave attenuation and vibration suppression by using plate-type elastic metamaterial, which is constituted of periodic double-sides stepped resonators deposited on a two-dimensional phononic plate with steel matrix. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are calculated by using the finite element method. In contrast to the typical phononic plates consisting of periodic stepped resonators deposited on a homogeneous steel plate, the proposed elastic metamaterial can yield large band gap in the low-frequency range, resulting in the low-frequency broadband elastic wave attenuation. The formation mechanisms of the band gap as well as the effects of material and geometrical parameters on the band gap are further explored numerically. Numerical results show that, the formation mechanism of opening the low-frequency band gap is attributed to the coupling between the local resonant Lamb modes of two-dimensional phononic plate and the resonant modes of the stepped resonators. The band gap can be significantly modulated by the material and geometrical parameters. The properties of broadband gaps of the proposed subwavelength scale elastic metamaterials can potentially be applied to vibration and noise reduction in the audio regime as well as broadband elastic wave confinement and modulation in ultrasonic region., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objective: To observe the effective mechanism and side effects of thalidomide to multiple myeloma (MM)., Methods: Ten cases of MM were studied, of which 3 were previously untreated and 7 refractory or relapsed. Bone marrow microvascular density (MVD) was detected by factor-VIII related antigen and CD(34) immunohistological staining and serum concentration of vascular endothelial growth factor (VEGF) before and after treatment was determined by ELISA. The initial dosage of thalidomide was 100 approximately 200 mg/d with a weekly escalation of 50 mg/d to 450 approximately 650 mg/d. The therapeutic effectiveness is classified into partial remission, improvement and uneffective according to the decrease of serum M protein and bone marrow myeloma cells. Anemia, renal function and blood electrolytes were also observed., Results: Before treatment, MVD was 73.32 +/- 28.80 and 32.30 +/- 12.50 in MM and control group, respectively, (P < 0.01). MVD in MM group decreased to 56.12 +/- 19.34 after treatment, and was of significant difference (P < 0.05) as compared to the pretreatment value. However, there was still a significant difference as compared to control (56.12 +/- 19.34 vs 32.30 +/- 12.50, P < 0.01). The concentration of VEGF significantly decreased after treatment [from (178.23 +/- 26.56) ng/L to (78.48 +/- 19.98) ng/L, P < 0.01)]. The total effective rate was 70%. There were no serious side effects., Conclusion: MVD and VEGF concentration were decreased obviously by thalidomide treatment. The dosage of 450 approximately 650 mg/d might be effective in refractory or initial MM.