In this study, a lightweight sandwich aircraft spoiler (AS) with a high stiffness-to-weight ratio was designed. Excellent mechanical properties were achieved by the synthetic use of topology ...optimization (TO), lattice structure techniques, and high-performance materials, i.e., titanium alloy and aluminum alloy. TO was first utilized to optimize the traditional aircraft spoiler to search for the stiffest structure with a limited material volume, where titanium alloy and aluminum alloy were used for key joints and other parts of the AS, respectively. We then empirically replaced the fine features inside the optimized AS with 3D kagome lattices to support the shell, resulting in a lightweight sandwich AS. Numerical simulations were conducted to show that the designed sandwich AS exhibited good mechanical properties, e.g., high bending rigidity, with a reduction in weight by approximately 80% when compared with that of the initial design model. Finally, we fabricated the designed model with photosensitive resin using a 3D printing technique.
The yak is a unique creature that thrives in low-oxygen environments, showcasing its adaptability to high-altitude settings with limited oxygen availability due to its unique respiratory system. ...However, the impact of hypoxia on alveolar type II (AT2) epithelial cell proliferation in yaks remains unexplored. In this study, we investigated the effects of different altitudes on 6-month-old yaks and found an increase in alveolar septa thickness and AT2 cell count in a high-altitude environment characterized by hypoxia. This was accompanied by elevated levels of hypoxia-inducible factor-1α (HIF-1α) and epidermal growth factor receptor (EGFR) expression. Additionally, we observed a significant rise in Ki67-positive cells and apoptotic lung epithelial cells among yaks inhabiting higher altitudes. Our in vitro experiments demonstrated that exposure to hypoxia activated HIF-1α, EGF, and EGFR expression leading to increased proliferation rates among yak AT2 cells. Under normal oxygen conditions, activation of HIF-1α enhanced EGF/EGFR expressions which subsequently stimulated AT2 cell proliferation. Furthermore, activation of EGFR expression under normoxic conditions further promoted AT2 cell proliferation while simultaneously suppressing apoptosis. Conversely, inhibition of EGFR expression under hypoxic conditions had contrasting effects. In summary, hypoxia triggers the proliferation of yak AT2 cells via activation facilitated by the HIF-1α/EGF/EGFR signaling cascade.
This paper is focused on a ratio-dependent predator-prey model with cross-diffusion of quasilinear fractional type. By applying the theory of local bifurcation, it can be proved that there exists a ...positive non-constant steady state emanating from its semi-trivial solution of this problem. Further based on the spectral analysis, such bifurcating steady state is shown to be asymptotically stable when the cross diffusion rate is near some critical value. Finally, numerical simulations and ecological interpretations of our results are presented in the discussion section.
Fermi surface (FS) topology is a fundamental property of metals and superconductors. In electron-doped cuprate Nd2−x
CeₓCuO₄ (NCCO), an unexpected FS reconstruction has been observed in optimal- and ...overdoped regime (x = 0.15–0.17) by quantum oscillation measurements (QOM). This is all the more puzzling because neutron scattering suggests that the antiferromagnetic (AFM) long-range order, which is believed to reconstruct the FS, vanishes before x = 0.14. To reconcile the conflict, a widely discussed external magnetic-field–induced AFM long-range order in QOM explains the FS reconstruction as an extrinsic property. Here, we report angle-resolved photoemission (ARPES) evidence of FS reconstruction in optimal- and overdoped NCCO. The observed FSs are in quantitative agreement with QOM, suggesting an intrinsic FS reconstruction without field. This reconstructed FS, despite its importance as a basis to understand electron-doped cuprates, cannot be explained under the traditional scheme. Furthermore, the energy gap of the reconstruction decreases rapidly near x = 0.17 like an order parameter, echoing the quantum critical doping in transport. The totality of the data points to a mysterious order between x = 0.14 and 0.17, whose appearance favors the FS reconstruction and disappearance defines the quantum critical doping. A recent topological proposal provides an ansatz for its origin.
Kagome lattice composed of transition-metal ions provides a great opportunity to explore the intertwining between geometry, electronic orders and band topology. The discovery of multiple competing ...orders that connect intimately with the underlying topological band structure in nonmagnetic kagome metals AV
Sb
(A = K, Rb, Cs) further pushes this topic to the quantum frontier. Here we report a new class of vanadium-based compounds with kagome bilayers, namely AV
Sb
(A = K, Rb, Cs) and V
Sb
, which, together with AV
Sb
, compose a series of kagome compounds with a generic chemical formula (A
Sb
)(V
Sb)
(m = 1, 2; n = 1, 2). Theoretical calculations combined with angle-resolved photoemission measurements reveal that these compounds feature Dirac nodal lines in close vicinity to the Fermi level. Pressure-induced superconductivity in AV
Sb
further suggests promising emergent phenomena in these materials. The establishment of a new family of layered kagome materials paves the way for designer of fascinating kagome systems with diverse topological nontrivialities and collective ground states.
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•Proposed a novel Archimedean spiral channel-based acoustic metasurface.•Developed a structural design optimization strategy to enhance sound absorption performance.•Realized the ...low-frequency sound absorption at a deep sub-wavelength scale.•Reduced the low-frequency noise of actual composite flexible machining equipment.
Suppression of low-frequency noise suppression is of high engineering importance. However, representative solution micro-perforated panels have limitations, including narrow effective sound absorption bands at low frequencies and excessive thickness. In this study, we design a novel Archimedean spiral channel-based acoustic metasurface (ASCBAM) founded on the theories of the coiling up space and perforated panel with extended tube. An analytical model is developed to formulate the sound absorption coefficient of the proposed ASCBAM. The sound absorption properties of the proposed ASCBAM are investigated by using analytical, computational and experimental methods. The corresponding sound absorption mechanism are revealed. A structural design optimization strategy is subsequently proposed to improve sound absorption performance in wide frequency range. Results suggest that the optimized ASCBAM can effectively achieve the sound absorption in the frequency range of 347–500 Hz at a deep sub-wavelength scale with a thickness-to-wavelength ratio of approximately 1/31.6. We finally apply the concept of the proposed ASCBAM to reduce the noise of actual composite flexible machining equipment, verifying its excellent low-frequency sound absorption capacity and confirming its strong ability to solve real-world engineering problems. The proposed acoustic metasurface offers unprecedented capabilities for low-frequency noise suppression in engineering fields with lightweight requirements.
In order to reveal the distribution and expression characteristics of the pulmonary ionocyte-related factors CFTR, ATP6V0D2, and ATP6V1C2 in the lungs of yaks of different ages. Explore the possible ...regulation of these pulmonary ionocyte-related factors in the yak lung for adaptation to high-altitude hypoxia. The localization and expression of CTFR, ATP6V0D2, and ATP6V1C2 in the lungs of newborn, juvenile, adult, and elderly yaks were studied using immunohistochemistry, quantitative reverse transcription PCR, and Western blotting. Immunohistochemistry showed that CFTR, ATP6V0D2 and ATP6V1C2 were mainly localized in the ciliated cells and club cells of the epithelial mucosal layer of the bronchus and its branches in the lungs. For the qRT-PCR, expression of CFTR, ATP6V0D2 and ATP6V1C2 in the yak lungs varied according to age. For Western blotting, CFTR expression in the newborn group was significantly higher than in the other three groups. ATP6V0D2 expression of the adult group was significantly higher. ATP6V1C2 expression was the highest in the juvenile group (
< 0.05). This study showed that ciliated cells and club cells were related to the pulmonary ionocytes in yaks. CFTR, ATP6V0D2, and ATP6V1C2 were related to adaptations of yak lungs to high altitude hypoxia, through prevention of airway damage.
This study aimed to develop an intraoperative prediction model to evaluate the risk of non-sentinel lymph node (NSLN) metastasis in Chinese breast cancer patients with 1-2 positive sentinel lymph ...nodes (SLNs). The clinicopathologic data of 714 patients with 1-2 positive SLNs were investigated. Univariate and multivariate analyses were performed to identify the risk factors of NSLN metastasis. A new mathematical prediction model was developed based on LASSO and validated in an independent cohort of 131 patients. The area under the receiver operating characteristic curve (AUC) was used to quantify performance of the model. Patients with NSLN metastasis accounted for 37.3% (266/714) and 34.3% (45/131) of the training and validation cohorts, respectively. A LASSO regression-based prediction model was developed and included the 13 most powerful factors (age group, clinical tumour stage, histologic type, number of positive SLNs, number of negative SLNs, number of SLNs dissected, SLN metastasis ratio, ER status, PR status, HER2 status, Ki67 staining percentage, molecular subtype and P53 status). The AUCs of training and validation cohorts were 0.764 (95% CI 0.729-0.798) and 0.777 (95% CI 0.692-0.862), respectively. We presented a new prediction model with excellent clinical applicability and diagnostic performance for use by clinicians as an intraoperative clinical tool to predict risk of NSLN metastasis in Chinese breast cancer patients with 1-2 positive SLNs and make the final decisions regarding axillary lymph node dissection.
The observation of replica bands in single-unit-cell FeSe on SrTiO3 (STO)(001) by angle-resolved photoemission spectroscopy (ARPES) has led to the conjecture that the coupling between FeSe electrons ...and the STO phonons are responsible for the enhancement of Tc over other FeSe-based superconductors. However the recent observation of a similar superconducting gap in single-unit-cell FeSe/STO(110) raised the question of whether a similar mechanism applies. Here we report the ARPES study of the electronic structure of FeSe/STO(110). Similar to the results in FeSe/STO(001), clear replica bands are observed. We also present a comparative study of STO(001) and STO(110) bare surfaces, and observe similar replica bands separated by approximately the same energy, indicating this coupling is a generic feature of the STO surfaces and interfaces. Our findings suggest that the large superconducting gaps observed in FeSe films grown on different STO surface terminations are likely enhanced by a common mechanism.
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