The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites. U-Pb dating analyses ...of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using SHRIMP II in the Beijing Ion-probe Center, acquire 206Pb/238U ages of 368+/-3.5 Ma (of granite, 95% confidence level, MSDW=1.23) and 362.9+/-6.1 Ma (of gneiss, 95% confidence level, MSDW = 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep ther-mal-dynamic process when the Gondwana continent began to break up in the Devonian period.
Hypertrophic scar (HS) formation is a skin fibroproliferative disease that occurs following a cutaneous injury, leading to functional and cosmetic impairment. To date, few therapeutic treatments ...exhibit satisfactory outcomes. The mechanical force has been shown to be a key regulator of HS formation, but the underlying mechanism is not completely understood. The Piezo1 channel has been identified as a novel mechanically activated cation channel (MAC) and is reportedly capable of regulating force-mediated cellular biological behaviors. However, the mechanotransduction role of Piezo1 in HS formation has not been investigated. In this work, we found that Piezo1 was overexpressed in myofibroblasts of human and rat HS tissues. In vitro, cyclic mechanical stretch (CMS) increased Piezo1 expression and Piezo1-mediated calcium influx in human dermal fibroblasts (HDFs). In addition, Piezo1 activity promoted HDFs proliferation, motility, and differentiation in response to CMS. More importantly, intradermal injection of GsMTx4, a Piezo1-blocking peptide, protected rats from stretch-induced HS formation. Together, Piezo1 was shown to participate in HS formation and could be a novel target for the development of promising therapies for HS formation.
The epithelial-mesenchymal transition (EMT) process has emerged as a central regulator of embryonic development, tissue repair and tumor malignancy. In recent years, researchers have specifically ...focused on how mechanical signals drive the EMT program in epithelial cells. However, how epithelial cells specifically leverage mechanical force to control the EMT process remains unclear. Here, we show that the
mechanically activated cation channel Piezo1 plays a critical role in the EMT. The Piezo1 is expressed in human primary epidermal keratinocytes (HEKs) and is responsible for the mechanical stretch-induced Ca
concentration. Inhibition of Piezo1 activation by the inhibitor GsMTx4 or by siRNA-mediated Piezo1 knockdown influenced the morphology and migration of HEKs. Moreover, Piezo1 activity also altered EMT-correlated markers expression in response to mechanical stretch. We propose that the mechanically activated cation channel Piezo1 is an important determinant of mechanical force-induced EMT in keratinocytes and might play similar roles in other epithelial cells.
Adipose‐derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs), which have promised a vast therapeutic potential in tissue regeneration. Recent studies have demonstrated that ...combining stem cells with mechanical stretch may strengthen the efficacy of regenerative therapies. However, the exact influences of mechanical stretch on MSCs still remain inconclusive. In this study, human ADSCs (hADSCs) were applied cyclic stretch stimulation under an in vitro stretching model for designated duration. We found that mechanical stretch significantly promoted the proliferation, adhesion and migration of hADSCs, suppressing cellular apoptosis and increasing the production of pro‐healing cytokines. For differentiation of hADSCs, mechanical stretch inhibited adipogenesis, but enhanced osteogenesis. Long‐term stretch could promote ageing of hADSCs, but did not alter the cell size and typical immunophenotypic characteristics. Furthermore, we revealed that PI3K/AKT and MAPK pathways might participate in the effects of mechanical stretch on the biological characteristics of hADSCs. Taken together, mechanical stretch is an effective strategy for enhancing stem cell behaviour and regulating stem cell fate. The synergy between hADSCs and mechanical stretch would most likely facilitate tissue regeneration and promote the development of stem cell therapy.
We developed a promising cathode material prepared by effective surface modification of Li-rich layered oxide (LLO) materials, using a Zr-based MOF (UIO-66-F4), as a precursor to produce in-situ ...MOF-derived ZrO2 (MDZ) coatings. A new method for F doping on LLO was also proposed. The MOF-assisted treatment renders a uniform nanoscale coating of ZrO2 and a porous structure of Li1.2Mn0.54Co0.13Ni0.13O2 hierarchical secondary microsphere. The rate capability, cycling stability, and first coulombic efficiency of LLO were significantly improved by the MOF-assisted treatment. The discharge capacity of the MOF-derived ZrO2 coated LLO (MDZ@LLO) material was 279 and 110.0 mAh g−1 at 0.1 C and 5 C, respectively. The capacity retention increased from 71.1% to 83.8% after 200 cycles at 1 C while the coulombic efficiency increased from 62% to 72% during the first cycle.
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•A facile method is applied to produce in situ MOF-derived ZrO2 coatings.•A new method of F doping is proposed for the Li-rich layered materials.•MOF-derived ZrO2 surface coating, F doping, porous LLO microspheres were obtained.•Electrochemical performance of MDZ@LLO cathode was greatly improved.
In this work, Li-rich layered oxide materials of Li1.2Mn0.54Co0.13Ni0.13O2 nano/micro hierarchical microrods are easily synthesized using a solvothermal method. Li2MnO3, a Li-rich layered oxide with ...a framework that is consistent with that of the host, is coated onto the surface of Li1.2Mn0.54Co0.13Ni0.13O2 microrods by a facile sol–gel method. Investigations with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM) and galvanostatic charge/discharge reactions reveal that surface-modified Li1.2Mn0.54Co0.13Ni0.13O2 microrods present better rate performance and cycling stability than other samples. The best electrochemical performance of the surface-modified Li1.2Mn0.54Co0.13Ni0.13O2 microrods is obtained with a layer composed of 5 wt% Li2MnO3 (∼10 nm thick), which provides very high discharge capacities of 244 and 159.5 mAh g−1 at C-rates of 1C and 10C, respectively (1C = 200 mAg−1), and excellent cycling stability (after 80 cycles, capacity retention of 96.0% at 1C). The composite's remarkably improved cyclability and rate capability are attributed to the combination of the nano/micro hierarchical microrod structure and the Li2MnO3-modified surface, which reduce structural degradation during electrochemical cycling. Results also show that the Li2MnO3 surface-modified Li1.2Mn0.54Co0.13Ni0.13O2 microrods significantly decelerate voltage decay and improve the initial coulombic efficiency (76.4%).
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•A facile method is applied to synthesize Li2MnO3-coated LLO microrods.•The Li2MnO3 coating suppresses voltage decay of Li-rich layered materials.•Li2MnO3 coating on LLO microrods provides superior electrochemical performance.•The Li2MnO3 coating remarkably improves the initial coulombic efficiency of LLO.•The LC-LLO-M cathode delivers a high capacity of 159.6 mAh g−1 at 10C.
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Phosphate material LiMnPO4 is popular for its high energy density (697 W·h·kg−1) and safety. When LiMnPO4 crystal grows, the potential barrier along b and c axis is strong, which ...makes the crystal grow along b axis to form a one-dimensional chain structure. However, the main migration channel of lithium ions in olivine structure is plane (0 1 0). By shortening the growth in the direction of b axis and enhancing the diffusion along the directions of a and c, two-dimensional nanosheets that are more conducive to the migration of lithium ions are formed. The dosage of polyols is the key factor guiding the dispersion of the crystals to the (0 1 0) plane. X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other means are used to characterize the samples. After experiments, we found that when the ratio of polyol/water was 2:1, the morphology of the synthesized sample was 20–30 nm thick nanosheets, which had the best electrochemical performance. At 0.1C, the discharge specific capacity reaches 148.9 mA·h·g−1, still reaches 144.3 mA·h·g−1 at the 50th cycle. and there is still 112.5 mA·h·g−1 under high rate (5C). This is thanks to the good dispersion of the material in the direction of the crystal plane (0 1 0). This can solve the problem of low conductivity and ionic mobility of phosphate materials.
Abstract Alkali‐activated materials (AAMs) were prepared using tungsten tailings via pressure molding and casting, and their high‐temperature resistances were analyzed. Variations in their ...compressive strength, gel, and physical phase transformation, pore structure, and morphology at different temperatures were investigated and comparatively analyzed. Results showed that the compressive strength of both AAMs first increased and then decreased with increasing temperature. At 600°C, the pressure‐molded AAM exhibited a considerably higher compressive strength (152.38 MPa) than the cast‐molded AAM (42.05 MPa). Thermogravimetric–differential scanning calorimetry, XRD, and FTIR analyses showed that the pressure‐molded AAM contained more gel phases than the cast‐molded AAM at the same temperature. The gel phase further polymerized and decomposed at high temperatures (>800°C), forming nepheline and zeolite crystals. Mercury intrusion porosimetry and scanning electron microscopy results revealed that pressure molding increases the contact between the gel and unreacted materials, effectively reducing the porosity and densifying the AAM. The pressure‐molded AAM had a considerably smaller pore diameter than the cast‐molded AAM; thus, the former had considerably higher compressive strength. The porosity and pore size of the pressure‐molded AAM gradually increased with the temperature, which polymerized the gel phase and eventually decomposed it; this increased its compressive strength first and then decreased.
Microgroove structures with helical pitches in a wavelength level are increasingly required in optical areas. However, conventional manufacturing techniques generate relatively high stresses during ...pressing, resulting in poor precision when forming microgrooves. This paper reports on the mechanism of the ultrasonic vibration-assisted microgroove forming of precise hot-pressed optical glass. A finite element (FE) thermocompression model of the viscoelastic material was developed and the entire forming process was numerically simulated using coupled thermal-structural analysis. The analysis of several process parameters was carried out using orthogonal experiments, from which the optimum combination of parameters was selected. The glass thermoforming process is also assisted by ultrasonic vibration. The thermal and mechanical effects of vibration improved material flow and optimized forming results. The average maximum stress in the glass during the forming process was only 3.04 × 10
Mpa, while the maximum stress in the hot-pressing stage without ultrasound was 1.648 Mpa. The stress results showed that the material-forming stress is significantly reduced.
Accurate battery remaining useful life (RUL) prediction plays an important role in ensuring reliable operation of electric vehicles. In this paper, a hybrid model based on Bayesian optimization of ...deep convolutional neural network and long short-term memory neural network (BO-DCNN-LSTM) is proposed for battery RUL prediction. Feature extraction of raw charging characteristic curves is performed by the multilayer CNN and preliminary capacity prediction is performed by the multilayer LSTM. The model performance is explored with different training, validation and testing strategies and different prediction starting points. Validation using NASA battery aging data shows that the mean absolute error (MAE) and root mean square error (RMSE) of the RUL prediction are 0.0139 Ah and 0.0195 Ah, respectively, when the prediction starting point is the 50th cycle. In addition, this paper visualizes the process of how the Bayesian optimization (BO) algorithm searches for the global optimal combinations in the high-dimensional hyperparameter space and discusses the impact of these hyperparameters on the prediction, filling the gap in this part of the research.
•A model of deep convolutional neural network and short-term neural network based on Bayesian optimization was proposed.•Proposed a “sequence to sequence” method for predicting the remaining service life of lithium-ion batteries.•Visualized the process of finding the globally optimal hyperparameter combination using Bayesian optimization algorithms.
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