Abstract
The Tibetan Plateau (TP) is sensitive to climate change in the land–atmosphere coupling mechanism due to its complex topographic features and unique geographic location. This study explored ...the teleconnection between pre-summer thawing of frozen soil over the TP and summer precipitation in East Asia in the Meiyu–Baiu rainy season (June, July) from 1981 to 2019 using maximum covariance analysis (MCA). The precipitation fields forced by thawing of frozen soil were calculated by the coupled manifold technique. The variations in East Asian precipitation are significantly impacted by thawing of frozen soil over the TP, with a variance explained ratio in the surrounding middle and lower reaches of Yangtze River (MLYR) of around 10%–20%. The MCA analysis also revealed that the thickness of pre-summer frozen soil thawing had a positive relationship with summer precipitation in the MLYR and southern Japan (fraction = 0.59, correlation ≈ 0.99). To find out the possible mechanism, composite analyses were conducted on atmospheric and surface components with reanalysis products. The analysis results suggested that more (less) frozen soil thawing would increase (decrease) the sensible heat and land surface temperature with enhanced (weakened) surface diabatic heating over the TP. Then, the positive (negative) surface diabatic heating would result in an enhanced (weakened) South Asia High extending eastward followed by stronger (weaker) upper troposphere (200 hPa) westerlies, as well as the West North Pacific Subtropical High extending westward. As a result, the northeastward movement of the integrated vapor transport intensified (weakened) with the westward extension (eastward retreat) of the Meiyu–Baiu rain belt, leading to more (less) precipitation in the MLYR and southern Japan. It is thus suggested that pre-summer thawing of frozen soil over the TP could play a vital role in regulating East Asian summer precipitation and movement of the Meiyu–Baiu rain belt.
The deprotonation mechanism for the phenolic hydroxyl and the complexing of metal ions with a commonly used food additive, propyl gallate (PG) were studied theoretically and experimentally. The ...interaction of procyanidins PC, epicatechin
(4 → 8) catechin, and its basic monomeric unit catechin (CA) with metal ions was studied by the fluorescence quenching spectra. The results showed that the 9-OH quinoid PG was formed at higher pH (10.9) by the oxidization of phenolic hydroxyl. The binding affinities (K
) and stoichiometry of these metal ions with PG were determined. The Al
in PG-Al complex Al(PG)(H
O)
Cl
was coordinated at the 8,9-OH doubly deprotonated catechol site with double chloride ions (Cl
) and double water molecules (H
O). The fluorescence quenching titration with Sn
, Zn
, Cu
, Al
and Fe
revealed that the stoichiometries of metal-bound PC were 1:1, 2:3, 2:3, 2:3 and 1:1, respectively. The presence of bovine serum albumin (BSA) could enhance the complexing strength of PC with metal ions.
This paper investigates a modified acoustic metamaterial system with local resonators coupled through linear springs. The proposed acoustic metamaterial system can provide three band gaps for ...broadband vibration suppression. First, the band structure of the modified acoustic metamaterial is calculated by using Bloch’s theorem under the assumption of infinite lattice. The existence of three band gaps is confirmed in the band structure. Effects of mass and spring parameters on the band gap behaviour of the modified metamaterial are investigated through a dimensionless parametric study. Based on the parametric study, optimal dimensionless parameters are proposed to achieve maximal total band gap width in the low frequency range. Subsequently, a more realistic finite lattice model is established. The transmittances of the conventional and modified metamaterial systems are compared. The three band gaps predicted from transmittances and broadband vibration suppression behaviour are consistent with the predictions from infinite lattice model using Bloch’s theorem. Finally, the time-domain responses are simulated and the superiority of the modified acoustic metamaterial over the conventional one is demonstrated.
MicroRNAs (miRNAs) are known to be critical regulators in cancer progression. MiR-451a is reported to be involved in the progression of many different forms of cancers, including osteosarcoma, ...colorectal cancer, and breast carcinoma. In this study, we illuminated the possible roles of miR-451a in the development of papillary thyroid carcinoma (PTC) cells in vitro and in vivo. MiR-451a was markedly down-expressed in PTC sample compared with paratumor tissue. Upregulation of miR-451a repressed PTC cells proliferation, migration ability and inhibited the invasiveness of PTC cells in vitro. Additional, miR-451a suppressed PTC cells growth and the lung metastasis of PTC cells in vivo, whereas downregulation of miR-451a caused opposite outcomes. Importantly, miR-451a inversely modulated the expression of Zinc Finger E-Box Binding Homeobox 1 (ZEB1) by directly binding to the 3′ untranslated region (UTR) of ZEB1 in PTC cells. The level of ZEB1 was negatively associated with miR-451a level in PTC tissues, and ZEB1 silencing mimicked the suppressive impacts of miR-451a on the proliferation, mobility, and invasive phenotypes of PTC cells. ZEB1 overexpression abrogated the inhibitory impacts of miR-451a on PTC cells. Together, this study revealed that miR-451a restrained the growth and metastatic phenotypes of PTC cells through targeting ZEB1.
Nonlinear energy harvesters have attracted wide research attentions to achieve broadband performances in recent years. Nonlinear structures have multiple solutions in certain frequency region that ...contains high-energy and low-energy orbits. It is effectively the frequency region of capturing a high-energy orbit that determines the broadband performance. Thus, maintaining large-amplitude high-energy-orbit oscillations is highly desired. In this paper, a voltage impulse perturbation approach based on negative resistance is applied to trigger high-energy-orbit responses of piezoelectric nonlinear energy harvesters. First, the mechanism of the voltage impulse perturbation and the implementation of the synthetic negative resistance circuit are discussed in detail. Subsequently, numerical simulation and experiment are conducted and the results demonstrate that the high-energy-orbit oscillations can be triggered by the voltage impulse perturbation method for both monostable and bistable configurations given various scenarios. It is revealed that the perturbation levels required to trigger and maintain high-energy-orbit oscillations are different for various excitation frequencies in the region where multiple solutions exist. The higher gain in voltage output when high-energy-orbit oscillations are captured is accompanied with the demand of a higher voltage impulse perturbation level.
This work investigates a self-tuning resonator composed of a slender clamped–clamped steel beam and a freely movable slider. The clamped–clamped beam exhibits hardening nonlinearity when it vibrates ...in large amplitude, providing a broad bandwidth of dynamic response. The moving slider changes the mass distribution of the whole structure, and provides a passive self-tuning approach for capturing the high-energy orbit of the structure. In the case without inclination, adequate inertial force that mainly depends on the vibration amplitude of the beam and the position of the slider can drive the slider to move from the side toward the centre of the beam. This movement amplifies the beam response when the excitation frequency is below 37 Hz in our prototyped device. In the multi-orbit frequency range (28–37 Hz), the self-tuning and magnification of beam response can be achieved when the slider is initially placed in an appropriate position on the beam. Once the beam is disturbed, however, the desired response in the high-energy orbit can be lost easily and cannot be reacquired without external assistance. In an improved design with a small inclination, the introduced small gravitational component enables the slider to move from the higher side toward the lower side when the beam amplitude is small. This property sacrifices the less efficient self-tuning region below 25 Hz, but can enable the beam to acquire and maintain the high-energy orbit response in the multi-orbit frequency range (28–39 Hz), which is resistant to disturbance. The proposed resonator in this paper not only broadens the frequency bandwidth of dynamic response, but also enables capture and maintenance of the high-energy orbit in a completely passive way. Such a passive self-tuning structure presents an advantage in the design of broadband vibration energy-harvesting systems.
Highlights
Create a hierarchical honeycomb-inspired triboelectric nanogenerator (TENG) with excellent transparency, compactness, lightweight and deformability.
Amplify capacitance variation by ...dividing large hollow space into numerous energy generation units with porous honeycomb architecture.
Demonstrate self-powered insole plantar pressure mapping applications by the self-sustained elastic nature of the h-TENG device.
Integrate the h-TENG into the morphing wing of small-unmanned aerial vehicles for converting flapping motions into electricity for the first time.
Flexible, compact, lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles (UAVs). Hierarchical honeycomb has the unique merits of compact mesostructures, excellent energy absorption properties and considerable weight to strength ratios. Herein, a honeycomb-inspired triboelectric nanogenerator (h-TENG) is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure. The wavy surface comprises a multilayered thin film structure (combining polyethylene terephthalate, silver nanowires and fluorinated ethylene propylene) fabricated through high-temperature thermoplastic molding and wafer-level bonding process. With superior synchronization of large amounts of energy generation units with honeycomb cells, the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage, short-circuit current and output power of 1207 V, 68.5 μA and 12.4 mW, respectively, corresponding to a remarkable peak power density of 0.275 mW cm
−3
(or 2.48 mW g
−1
) under hand pressing excitations. Attributed to the excellent elastic property of self-rebounding honeycomb structure, the flexible and transparent h-TENG can be easily pressed, bent and integrated into shoes for real-time insole plantar pressure mapping. The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time. This research demonstrates this new conceptualizing single h-TENG device's versatility and viability for broad-range real-world application scenarios.
Analytical and finite element electromechanical models that take into account the fact that the piezoelectric sheet does not cover the whole substrate beam are developed. A linear analysis of the ...analytical model is performed to determine the optimal load resistance. The analytical and finite element models are validated with experimental measurements. The results show that the analytical model that takes into account the fact that the piezoelectric patch does not cover the whole beam predicts accurately the experimental measurements. The finite element results yield a slight discrepancy in the global frequency and a slight overestimation in the value of the harvested power at resonance. On the contrary, using an approximate analytical model based on mode shapes of the full covered beam leads to erroneous results and overestimation of the global frequency as well as the level of harvested power. In order to design enhanced piezoelectric energy harvesters that can generate energy at low-frequency excitations, further analysis is performed to investigate the effects of varying the length of the piezoelectric material on the natural frequency and the performance of the harvester. The results show that there is a compromise between the length of the piezoelectric material, the electrical load resistance, and the available excitation frequency. By quantifying this compromise, we optimize the performance of beam–mass systems to efficiently harvest energy from a specified low frequency of the ambient vibrations.
Gallbladder carcinoma (GBC), an aggressive malignant tumor of the biliary system, is characterized by high cellular heterogeneity and poor prognosis. Fewer data have been reported in GBC than other ...common cancer types. Multi-omics data will contribute to the understanding of the molecular mechanisms of cancer, cancer diagnosis and prognosis. Herein, to provide better understanding of the molecular events in GBC pathogenesis, we developed GBCdb ( http://tmliang.cn/gbc/ ), a user-friendly interface for the query and browsing of GBC-associated genes and RNA interaction networks using published multi-omics data, which also included experimentally supported data from different molecular levels. GBCdb will help to elucidate the potential biological roles of different RNAs and allow for the exploration of RNA interactions in GBC. These resources will provide an opportunity for unraveling the potential molecular features of Gallbladder carcinoma.
We studied the fusibility and flow properties of laboratory ash and Shell gasifier slag from the same coal sample (Chinese Huainan coal). The physical properties of ash and slag were analyzed with ...X-ray fluorescence, X-ray diffraction, and scanning electron microscopy. The fusion temperature and the experiment viscosity were measured for the ash and slag with the addition of fluxing CaO. Ash and slag have properties that were approximated by the SiO
2–Al
2O
3–‘FeO’–CaO system. The computer software package FactSage was used to predict the proportion of solid phase and the mineral phase formed as a function of the composition and the temperature of the SiO
2–Al
2O
3–‘FeO’–CaO system. The results show that the fusion temperatures and the temperature of critical viscosity (
T
cv) of ash are always higher than that of slag. Also, the viscosity of ash is always higher than that of slag at the slag tapping temperature range of 1400–1500
°C, and the hysteresis between the heating and cooling cycles for ash is more obvious than that of slag because of different physical properties. The fusion temperature and
T
cv of ash and slag decrease with increasing CaO content, whereas those values increase rapidly with CaO content higher than 35%. Also, the sensitivity of the viscosity of the ash and slag with temperature decreases with increasing CaO content because the sensitivity of the phase equilibria of in the SiO
2–Al
2O
3–‘FeO’–CaO system to temperature excursions decreases with increasing CaO content.
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