Programmable gear-based mechanical metamaterials.

Elastic properties of classical bulk materials can hardly be changed or adjusted in operando, while such tunable elasticity is highly desired for robots and smart machinery. Although possible in reconfigurable metamaterials, continuous tunability in existing designs is plagued by issues such as structural instability, weak robustness, plastic failure and slow response. Here we report a metamaterial design paradigm using gears with encoded stiffness gradients as the constituent elements and organizing gear clusters for versatile functionalities. The design enables continuously tunable elastic properties while preserving stability and robust manoeuvrability, even under a heavy load. Such gear-based metamaterials enable excellent properties such as continuous modulation of Young's modulus by two orders of magnitude, shape morphing between ultrasoft and solid states, and fast response. This allows for metamaterial customization and brings fully programmable materials and adaptive robots within reach.

Homogenization of an acoustic coating with a steel backing subject to an obliquely incident sound.

An effective homogenization model for the acoustic coating of underwater structures is important for reducing the complexity of acoustic scattering computation, which arises from the huge difference in scale between the integral structure and the inhomogeneous microstructure of the coating. The main difficulty of this homogenization arises from the oblique-incidence effect of external sound waves and the interface effect between the coating and backing. In this work, a hybrid method, combining the Bloch wave analysis and retrieval technique, is proposed to characterize the acoustic behavior of the voided coating backed with a steel plate under the action of external sound waves with an arbitrary incident angle. The effectiveness of this method is validated by numerical simulations and comparison with the Bloch wave method and the traditional retrieval method. The influence of the shear-wave effect under obliquely incident sound waves and the coupling effect between the coating and the backing on the homogenization model is investigated in detail, providing a comprehensive understanding of the effective acoustic behavior of the coating.

A Visual Fault Detection Method for Induction Motors Based on a Zero-Sequence Current and an Improved Symmetrized Dot Pattern.

Motor faults, especially mechanical faults, reflect eminently faint characteristic amplitudes in the stator current. In order to solve the issue of the motor current lacking effective and direct signal representation, this paper introduces a visual fault detection method for an induction motor based on zero-sequence current and an improved symmetric dot matrix pattern. Empirical mode decomposition (EMD) is used to eliminate the power frequency in the zero-sequence current derived from the original signal. A local symmetrized dot pattern (LSDP) method is proposed to solve the adaptive problem of classical symmetric lattice patterns with outliers. The LSDP approach maps the zero-sequence current to the ultimate coordinate and obtains a more intuitive two-dimensional image representation than the time-frequency image. Kernel density estimation (KDE) is used to complete the information about the density distribution of the image further to enhance the visual difference between the normal and fault samples. This method mines fault features in the current signals, which avoids the need to deploy additional sensors to collect vibration signals. The test results show that the fault detection accuracy of the LSDP can reach 96.85%, indicating that two-dimensional image representation can be effectively applied to current-based motor fault detection.

Identification of compounds from Paris polyphylla (ChongLou) active against Dactylogyrus intermedius.

The present study was designated to ascertain the anthelmintic activity of the rhizomes of Paris polyphylla and to isolate and characterize the active constituents. The methanol extract from rhizomes of P. polyphylla showed significant anthelmintic activity against Dactylogyrus intermedius with the median effective concentration (EC50) 22.5 mg L(-1). Based on this finding, the methanol extract was fractionated by silica gel column chromatography in a bioassay-guided fractionation yielding 2 bioactive compounds, the structures of these compounds were elucidated as formosanin C and polyphyllin VII. The in vivo tests revealed that formosanin C and polyphyllin VII were significantly effective against D. intermedius with EC50 values of 0.6 and 1.2 mg L(-1), respectively. The acute toxicities (LC50) of formosanin C and polyphyllin VII for grass carp were 2.8 and 2.9 mg L(-1), respectively. The overall results provide important information for the potential application of formosanin C and polyphyllin VII in the therapy of serious infection caused by D. intermedius.

Analysis of absorption performances of anechoic layers with steel plate backing.

Rubber layers with air-filled cavities or local resonance scatters can be used as anechoic coatings. A lot of researches have focused on the absorption mechanism of the anechoic coatings. As the anechoic coatings are bonded to the hull of submarine, the vibration of the hull should not be neglected when the analysis of the absorption characters is carried out. Therefore, it is more reasonable to treat the anechoic coating and the backing as a whole when the acoustic performance is analyzed. Considering the effects of the steel plate backing, the sound absorption performances on different models of anechoic coatings are investigated in this paper. The Finite Element Method is used to illustrate the vibrational behaviors of the anechoic coatings under the steel backings by which the displacement contours is obtained for analysis. The theoretical results show that an absorption peak is induced by the resonance of the steel slab and rubber layer. At the frequency of this absorption peak, the steel plate and the coating vibrates longitudinally like a mass-spring system in which the steel slab serves for mass and the coating layer is the spring. To illuminate the effects of the steel slab backing on the acoustic absorption, the thicknesses of the steel slab and the anechoic layer are discussed. Finally, an experiment is performed and the results show a good agreement with the theoretical analysis.

Investigations of Thermal, Mechanical, and Gas Barrier Properties of PA11-SiO2 Nanocomposites for Flexible Riser Application.

Acidic gas penetration through the internal pressure sheath of a flexible riser tends to cause a corrosive environment in the annulus, reducing the service life of the flexible riser. Nanoparticles can act as gas barriers in the polymer matrix to slow down the gas permeation. Herein, we prepared PA11/SiO2 composites by the melt blending method. The effect of adding different amounts of SiO2 to PA11 on its gas barrier properties was investigated by conducting CO2 permeation tests between 20 °C and 90 °C. As the temperature increased, the lowest value of the permeability coefficient that could be achieved for the PA11 with different contents of SiO2 increased. The composites PA/0.5% SiO2 and PA/1.5% SiO2 had the lowest permeation coefficients in the glassy state (20 °C) and rubbery state (≥50 °C). We believe that this easy-to-produce industrial PA/SiO2 composite can be used to develop high-performance flexible riser barrier layers. It is crucial for understanding riser permeation behavior and enhancing barrier qualities.

Effects of locally resonant modes on underwater sound absorption in viscoelastic materials.

Recently, by introducing locally resonant scatterers with spherical shape proposed in phononic crystals into design of underwater sound absorption materials, the low-frequency underwater sound absorption phenomenon induced by the localized resonances is observed. To reveal this absorption mechanism, the effect of the locally resonant mode on underwater sound absorption should be studied. In this paper, the finite element method, which is testified efficiently by comparing the calculation results with those of the layer multiple scattering method, is introduced to investigate the dynamic modes and the corresponding sound absorption of localized resonance. The relationship between the resonance modes described with the displacement contours of one unit cell and the corresponding absorption spectra is discussed in detail, which shows that the localized resonance leads to the absorption peak, and the mode conversion from longitudinal to transverse waves at the second absorption peak is more efficient than that at the first one. Finally, to show the modeling capability of FEM and investigate shape effects of locally resonant scatterers on underwater sound absorption, the absorption properties of viscoelastic materials containing locally resonant scatterers with ellipsoidal shape are discussed.

[Retracted] Long non­coding RNA MCM3AP­AS1 drives ovarian cancer progression via the microRNA­143­3p/TAK1 axis.

Following the publication of this article, the authors' attention was drawn to the fact that Table I and Fig. 6 contained some errors: The former contained some incorrect data, whereas the latter contained some inappropriately selected tumor images. Following a further investigation in the Editorial Office, it has come to light that there were other possible anomalies associated with the presentation of the tumor images, and also that parts of the figure may have been published previously. Taking everything into consideration, the Editor has decided that the article should be retracted from the publication due to a lack of confidence in the data presented in this article. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not received any reply. The Editor regrets any inconvenience that the retraction of the paper will cause. [the original article was published in Oncology Reports 44: 1375­1384, 2020; DOI: 10.3892/or.2020.7694].

Hyperoxia sensitizes hypoxic HeLa cells to ionizing radiation by downregulating HIF­1α and VEGF expression.

The current study investigated whether hyperoxia may reverse hypoxia­induced radioresistance (RR) in cervical cancer. Human HeLa cells exposed to hypoxic, normoxic or hyperoxic conditions were irradiated using X­rays. Cell proliferation and apoptosis were analyzed using MTT assays and flow cytometry. The expression levels of hypoxia­inducible factor­1α (HIF­1α), VEGF165, VEGFRs, Akt and ERK were measured via western blotting and/or ELISA. The results demonstrated that hypoxia stimulated HIF­1α and VEGF expression, and induced RR in HeLa cells. The administration of recombinant VEGF or the forced expression of VEGF promoted RR, whereas inactivating HIF­1α or blocking the VEGF­VEGFR interaction abrogated hypoxia­induced RR. Notably, hyperoxia decreased the level of hypoxia­stimulated HIF­1α and VEGF, and enhanced radiosensitivity in hypoxic HeLa cells. The results demonstrated that hyperoxia suppressed the hypoxia­activated Akt and ERK signaling pathways in HeLa cells. Therefore, a high O2 concentration may be considered as a radiotherapeutic sensitizer for hypoxic HeLa cells.

Long non­coding RNA MCM3AP­AS1 drives ovarian cancer progression via the microRNA­143­3p/TAK1 axis.

The long non­coding RNA (lncRNA) MCM3AP antisense 1 (MCM3AP­AS1) has previously been shown to be a key regulator of multiple types of cancer; however whether it is important in the context of ovarian cancer (OC) is uncertain. The present study determined that MCM3AP­AS1 expression in samples from patients with OC was significantly increased, and was associated with tumor stage, presence of lymph node metastases and poorer overall survival. The role of this lncRNA was investigated in vitro, and it was observed that knockdown of MCM3AP­AS1 impaired OC cell proliferation, migration and colony formation. Similarly, it disrupted tumor growth in vivo. The present study further determined that MCM3AP­AS1 was able to directly interact with microRNA (miRNA or miR)­143­3p as a competing endogenous (ce)RNA for this miRNA, thereby regulating the expression of transforming growth factor­ß­activated kinase 1 (TAK1), a known target of miR­143­3p in OC. Consistent with this, inhibition of miR­143­3p was sufficient to partially reverse the effects of MCM3AP­AS1­knockdown, which inhibited the proliferation, migration and invasion of OC cells. Together, these results indicate that MCM3AP­AS1 serves as an oncogenic lncRNA in OC by binding to miR­143­3p and thereby promoting TAK1 expression, and suggest that this lncRNA may be a possible target for therapy in OC.

RETRACTED: Long non-coding RNA TTN-AS1 promotes tumorigenesis of ovarian cancer through modulating the miR-139-5p/ROCK2 axis.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief and the corresponding author. The panels from Figure 2C appear similar to panels from Figure 2C (after 180-deg flip) of the article previously published by Chunling Xu, Chunmei Hu, Yingxue Wang and Shu Liu in Biomedicine & Pharmacotherapy 117 (2019) 109153 https://doi.org/10.1016/j.biopha.2019.109153 and Figure 8B of the article previously published by Dongmei Han, Jianfeng Wang and Guanghui Cheng in Oncotarget 9 (2018) 2395-2409 https://doi.org/10.18632/oncotarget.23416. The panels from figure 2G appear similar to panels from Figure 6D (after 180-deg flip) of the article previously published by Zhiguang Yang, Xingyu Lin, Peng Zhang, Yunpeng Liu, Zihao Liu, Benxin Qian, Xing Liu and Guoguang Shao in Biomedicine & Pharmacotherapy 124 (2020) 109858 https://doi.org/10.1016/j.biopha.2020.109858 and Figure 5c of the article previously published by Zhen Liang, Xiao Wang, Xin Xu, Bo Xie, Alin Ji, Shuai Meng, Shiqi Li, Yi Zhu, Jian Wu, Zhenghui Hu, Yiwei Lin, Xiangyi Zheng, Liping Xie and Ben Liu in Molecular Cancer 16 (2017) 96 https://doi.org/10.1186/s12943-017-0664-1.

Theoretical requirements and inverse design for broadband perfect absorption of low-frequency waterborne sound by ultrathin metasurface.

Effective absorption of low-frequency waterborne sound with subwavelength absorbers has always been a challenging work. In this paper, we derive two theoretical requirements for broadband perfect absorption of low-frequency waterborne sound by ultrathin acoustic metasurface under a finite-thickness steel plate followed by semi-infinite air. Based on the theoretical requirements, an acoustic metasurface, a rubber layer embedded periodically with cavities, is inversely designed to achieve perfect absorption at 500 Hz. The metasurface is as thin as 1% of the working wavelength and maintains a substantially high absorptance over a relatively broad bandwidth. The perfect absorption peak is attributed to the overall resonance mode of the metasurface/steel plate system. Besides, high absorption can still be achieved even if the loss factor of the given rubber material cannot meet the ideal requirement. Finally, a strategy to utilize the inherent frequency-dependent characteristics of dynamic parameters of rubber material is suggested to achieve an ultra-broadband perfect absorption. When the frequency-dependent characteristics of the given rubber matrix cannot meet the theoretical requirements, a broadband super-absorption can still be realized by properly designing the frequency position of perfect absorption of the cavity-based metasurface.

RETRACTED: Long non-coding RNA LINC00460 promotes epithelial ovarian cancer progression by regulating microRNA-338-3p.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief and the authors. Panels from Figures 2C and 2D appear similar to panels from Figures 4D and 4F of the article published by Hai-Xiang Yu, Xiao-Long Wang, Le-Ning Zhang, Ji Zhang and Wei Zhao in Biomedicine & Pharmacotherapy 109 (2019) 751-761 https://doi.org/10.1016/j.biopha.2018.09.110. Panels from Figure 3B appear similar to panels from Figure 3D of the article previously published by Yuanyuan Meng, Qi Li, Lianwei Li and Rong Ma in Biological Chemistry 399 (2017) 93-100 https://doi.org/10.1515/hsz-2017-0199. The 'GAPDH' Western Blots from Figure 3C appear similar to the 'AKT' Western Blots from Figure 6 of the article previously published by Lan Wu, Bo Shi, Kexin Huang and Guoyu Fan in the Oncology Reports 34 (2015) 2797-2805 https://doi.org/10.3892/or.2015.4251 and the 'GAPDH' Western Blots from Figure 4D of the article previously published by Tao Peng, Lixiang Zhou, Ling Zuo and Yongxin Luan in the Oncology Reports 35 (2016) 1057-1064 https://doi.org/10.3892/or.2015.4406.

Acoustic cloak based on Bézier scatterers.

Among the different approaches proposed to design acoustic cloaks, the one consisting on the use of an optimum distribution of discrete scatters surrounding the concealing object has been successfully tested. The feasibility of acoustic cloaks mainly depends on the number and shape of the scatterers surrounding the object to be cloaked. This work presents a method allowing the reduction of the number of discrete scatterers by optimizing their external shape, which is here defined by a combination of cubic Bézier curves. Based on scattering cancellation, a two-dimensional directional cloak consisting of just 20 Bézier scatters has been designed, fabricated and experimentally characterized. The method of fundamental solutions has been implemented to calculate the interaction of an incident plane wave with scatterers of arbitrary shape. The acoustic cloak here proposed shows a performance, in terms of averaged visibility, similar to that consisting of 120 scatterers with equal circular cross sections. The operational frequency of the proposed cloak is 5940 Hz with a bandwidth of about 110 Hz.

Band transition and topological interface modes in 1D elastic phononic crystals.

In this report, we design a one-dimensional elastic phononic crystal (PC) comprised of an Aluminum beam with periodically arranged cross-sections to study the inversion of bulk bands due to the change of topological phases. As the geometric parameters of the unit cell varies, the second bulk band closes and reopens forming a topological transition point. This phenomenon is confirmed for both longitudinal waves and bending waves. By constructing a structural system formed by two PCs with different topological phases, for the first time, we experimentally demonstrate the existence of interface mode within the bulk band gap as a result of topological transition for both longitudinal and bending modes in elastic systems, although for bending modes, additional conditions have to be met in order to have the interface mode due to the dispersive nature of the bending waves in uniform media compared to the longitudinal waves.

Ultra-low and ultra-broad-band nonlinear acoustic metamaterials.

Linear acoustic metamaterials (LAMs) are widely used to manipulate sound; however, it is challenging to obtain bandgaps with a generalized width (ratio of the bandgap width to its start frequency) >1 through linear mechanisms. Here we adopt both theoretical and experimental approaches to describe the nonlinear chaotic mechanism in both one-dimensional (1D) and two-dimensional (2D) nonlinear acoustic metamaterials (NAMs). This mechanism enables NAMs to reduce wave transmissions by as much as 20-40 dB in an ultra-low and ultra-broad band that consists of bandgaps and chaotic bands. With subwavelength cells, the generalized width reaches 21 in a 1D NAM and it goes up to 39 in a 2D NAM, which overcomes the bandwidth limit for wave suppression in current LAMs. This work enables further progress in elucidating the dynamics of NAMs and opens new avenues in double-ultra acoustic manipulation.

Cisplatin induces HepG2 cell cycle arrest through targeting specific long noncoding RNAs and the p53 signaling pathway.

Cisplatin has been used effectively in the treatment of hepatocellular carcinoma (HCC). Long noncoding RNAs (lncRNAs) were recently reported to contribute to the pathogenesis and progression of HCC. Their molecular mechanism related to cisplatin treatment remains unclear. The purpose of this study is to identify specific lncRNAs and to clarify their functions in HCC after cisplatin exposure. Reannotation and identification of differentially expressed lncRNAs were performed using the microarray data set GSE38122 in the Gene Expression Omnibus database. Four significantly differentially expressed lncRNAs (RP11-134G8.8, RP11-612B6.2, RP11-363E7.4 and RP1-193H18.2) were identified in HepG2 cells exposed to cisplatin by bioinformatics methods. The upregulated RP11-134G8.8 and RP11-363E7.4 and the downregulated RP1-193H18.2 were confirmed by reverse transcription-quantitative polymerase chain reaction. Furthermore, 57 significant co-expressing genes and their corresponding pathways were annotated and identified. The p53 signaling pathway showed the most significant difference among all pathways. Based on these results, the cell cycle and three key genes, cyclin-dependent kinase inhibitor 1A (CDKN1A, also known as p21), tumor protein p53 inducible protein 3 (TP53I3) and wild-type p53-induced phosphatase 1 (Wip1, also known as PPM1D), were examined. CDKN1A, TP53I3 and PPM1D were all downregulated by RP1-193H18.2 but upregulated by RP11-134G8.8 and RP11-363E7.4. And obvious S phase arrest was induced by cisplatin treatment for 24 h in HepG2 cells. Finally, the immunofluorescence results showed upregulation of TP53I3 and Wip1 and downregulation of p21 at the protein level. The results suggested that the lncRNAs RP11-134G8.8, RP11-363E7.4 and RP1-193H18.2, and their co-expression genes, which annotated into the p53 signaling pathway, could be potential targets for cisplatin treatment.

Broadband and tunable one-dimensional strongly nonlinear acoustic metamaterials: Theoretical study.

This paper focuses on the dispersion properties and mechanism of the one-dimensional strongly nonlinear acoustic metamaterials (NAMMs) based on the homotopy method. The local bifurcation mechanism, which is different from conventional local resonance, is found. It is demonstrated that the local period-doubling bifurcation of multiple cells will induce chaotic bands in the NAMMs, which can significantly expand the bandwidth for wave suppression. The saddle-node bifurcation leads the system state jumping to the chaotic branch. Furthermore, the amplitude-dependent dispersion properties enable NAMMs to manipulate elastic waves externally. Study of broadband tunable abilities reveals that stronger nonlinearity (larger nonlinear coefficient or higher amplitude) presents a broader nonlinear band gap and larger transmission loss. Moreover, with less attached mass, a low frequency and broadband are achievable simultaneously. This research may provide useful approaches for elastic wave control.