The purpose of this work is to study the efficient numerical solvers for time-dependent conservative space fractional diffusion equations. Specifically, for the discretized Toeplitz-like linear ...system, we aim to study efficient preconditioning based on a matrix-splitting iteration method. We propose a scaled tridiagonal and Toeplitz-like splitting iteration method. Its asymptotic convergence property is first established. Further, based on the induced preconditioner, a fast circulant-like preconditioner is developed to accelerate the convergence of the Krylov Subspace iteration methods. Theoretical results suggest that the fast preconditioner can inherit the effectiveness of the original induced preconditioner. Numerical results also demonstrate its efficiency.
An auxetic metamaterial is a type of mechanical metamaterial that has a negative Poisson's ratio. Most auxetic metamaterials are truss-based or originate from Boolean operations of simple geometries. ...Herein, we introduce a new 3D auxetic metamaterial that is mathematically generated from an implicit expression. Further, this metamaterial is fabricated by 3D printing using a flexible material, which allows it to recover from large deformations. The buckling-induced auxetic behavior of the metamaterial was first evaluated via compression tests and finite element analyses. A nickel layer was then plated onto the surface to enhance its stiffness, strength, and conductivity without loss of auxeticity and resilience. The integration of 3D printing and electroless plating enabled accurate control over the mechanical and conduction properties of the auxetic metamaterial; these properties are presented as contour maps for guidance in functional applications.
We propose a novel 3D auxetic metamaterial derived from a mathematically defined triply periodic minimal surface. The stiffness, strength, and conductivity of the metamaterial are enhanced by nickel plating without loss of auxeticity and resilience. The effective mechanical and conduction properties were mapped against geometric parameters, including relative density and nickel layer thickness. These data maps provide insight for tuning its performance over a broad range.
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•We propose a novel 3D auxetic metamaterial derived from a mathematically defined triply periodic minimal surface.•Nickel plating enhanced the stiffness, strength, and conductivity of the metamaterial without the auxeticity and resilience.•The relationships between geometric parameters and material properties of the metamaterial were discussed.•These relationships provide insight into tuning its performance over a broad range.
•The review shows building energy consumption modeling and forecasting techniques.•Eight specific data-driven forecasting methods are described.•A focus is given on the data pre-processing methods ...and forecasting algorithms.•The supervised, unsupervised, reinforcement and machine learning tasks is discussed.
Building energy consumption modeling and forecasting is essential to address buildings energy efficiency problems and take up current challenges of human comfort, urbanization growth and the consequent energy consumption increase. In a context of integrated smart infrastructures, data-driven techniques rely on data analysis and machine learning to provide flexible methods for building energy prediction. The present paper offers a review of studies developing data-driven models for building scale applications. The prevalent methods are introduced with a focus on the input data characteristics and data pre-processing methods, the building typologies considered, the targeted energy end-uses and forecasting horizons, and accuracy assessment. A special attention is also given to different machine learning approaches. Based on the results of this review, the latest technical improvements and research efforts are synthesized. The key role of occupants’ behavior integration in data-driven modeling is discussed. Limitations and research gaps are highlighted. Future research opportunities are also identified.
The Tibetan Plateau (TP) exerts significant impacts on its surroundings through its thermal and dynamical processes. In recent decades, especially since 2000, the TP has been experiencing a more ...rapid warming than its surrounding regions. This study uses Moderate Resolution Imaging Spectroradiometer (MODIS) monthly averaged land surface temperature (LST) product to detect the recent warming trend with respect to elevations over the entire TP, because the number of weather stations from China Meteorological Administration (CMA) is rather limited in the western TP and, furthermore, are unavailable for areas higher than 4,800 m above sea level (ASL). The trend of MODIS LST is first validated against the warming trend estimated from near-surface air temperatures measured at CMA stations and the warming rate dependence on elevation is then derived from MODIS LST. The results indicate that the warming rate increases from 3,000 to 4,800 m ASL, and then becomes quite stable with a slight decline near the highest elevations. This altitudinal dependence of the warming rate has a significant implication for TP water resources and environmental changes, since most glaciers and snow surfaces are located above 5,000 m ASL over the TP.
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•We propose an inverse design method for auxetic metamaterials using deep learning.•We designed novel 2D auxetic metamaterials based on Voronoi tessellation for the training ...dataset.•The trained neural network can generate 2D auxetic metamaterials with user-desired Young’s moduli and Poisson’s ratios.•The proposed method can easily be extended to the inverse design of other architected materials.
As typical mechanical metamaterials with negative Poisson’s ratios, auxetic metamaterials exhibit counterintuitive auxetic behaviors that are highly dependent on their geometric arrangements. The realization of the geometric arrangement required to achieve a negative Poisson’s ratio relies considerably on the experience of designers and trial-and-error approaches. This report proposes an inverse design method for auxetic metamaterials using deep learning, in which a batch of auxetic metamaterials with a user-defined Poisson’s ratio and Young’s modulus can be generated by a conditional generative adversarial network without prior knowledge. The network was trained based on supervised learning using a large number of geometrical patterns generated by Voronoi tessellation. The performance of the network was demonstrated by verifying the mechanical properties of the generated patterns using finite element method simulations and uniaxial compression tests. The successful realization of user-desired properties can potentially accelerate the inverse design and development of mechanical metamaterials.
Patients with lymph node (LN)-positive pancreatic ductal adenocarcinoma (PDAC) have extremely poor survival rates. Circular RNAs (circRNAs), a newly discovered type of endogenous noncoding RNAs, have ...been proposed to mediate the progression of diverse types of tumors. However, the role and underlying regulatory mechanisms of circRNAs in the LN metastasis of PDAC remain unknown.
Next-generation sequencing was used to identify differentially expressed circRNAs between PDAC and normal adjacent tissues. In vitro and in vivo experiments were conducted to evaluate the functional role of circNFIB1. RNA pulldown and luciferase assays were performed to examine the binding of circNFIB1 and miR-486-5p.
In the present study, we identified that a novel circRNA (circNFIB1, hsa_circ_0086375) was downregulated in PDAC and negatively associated with LN metastasis in PDAC patients. Functionally, circNFIB1 knockdown promoted lymphangiogenesis and LN metastasis of PDAC both in vitro and in vivo. Mechanistically, circNFIB1 functioned as a sponge of miR-486-5p, and partially reversed the effect of miR-486-5p. Moreover, circNFIB1 attenuated the oncogenic effect of miR-486-5p and consequently upregulated PIK3R1 expression, which further downregulated VEGF-C expression through inhibition of the PI3K/Akt pathway, and ultimately suppressed lymphangiogenesis and LN metastasis in PDAC.
Our findings provide novel insight into the underlying mechanism of circRNA-mediated LN metastasis of PDAC and suggest that circNFIB1 may serve as a potential therapeutic target for LN metastasis in PDAC.
Abstract
Near-surface air temperature variability and the reliability of temperature extrapolation within glacierized regions are important issues for hydrological and glaciological studies that ...remain elusive because of the scarcity of high-elevation observations. Based on air temperature data in 2019 collected from 12 automatic weather stations, 43 temperature loggers, and 6 national meteorological stations in 6 different catchments, this study presents air temperature variability in different glacierized and nonglacierized regions and assesses the robustness of different temperature extrapolations to reduce errors in melt estimation. The results show high spatial variability in temperature lapse rates (LRs) in different climatic contexts, with the steepest LRs located on the cold and dry northwestern Tibetan Plateau and the lowest LRs located on the warm and humid monsoonal-influenced southeastern Tibetan Plateau. Near-surface air temperatures in high-elevation glacierized regions of the western and central Tibetan Plateau are less influenced by katabatic winds and thus can be linearly extrapolated from off-glacier records. In contrast, the local katabatic winds prevailing on the temperate glaciers of the southeastern Tibetan Plateau exert pronounced cooling effects on the ambient air temperature, and thus, on-glacier air temperatures are significantly lower than that in elevation-equivalent nonglacierized regions. Consequently, linear temperature extrapolation from low-elevation nonglacierized stations may lead to as much as 40% overestimation of positive degree-days, particularly with respect to large glaciers with a long-flowline distances and significant cooling effects. These findings provide noteworthy evidence that the different LRs and relevant cooling effects on high-elevation glaciers under distinct climatic regimes should be carefully accounted for when estimating glacier melting on the Tibetan Plateau.
An organic–inorganic halide CH3NH3SnI3 perovskite with significantly improved structural stability is obtained via pressure‐induced amorphization and recrystallization. In situ high‐pressure ...resistance measurements reveal an increased electrical conductivity by 300% in the pressure‐treated perovskite. Photocurrent measurements also reveal a substantial enhancement in visible‐light responsiveness. The mechanism underlying the enhanced properties is shown to be associated with the pressure‐induced structural modification.
Accumulating evidence suggests that circular RNAs (circRNAs) are important participants in cancer progression. However, the biological processes and underlying mechanisms of circRNAs in pancreatic ...ductal adenocarcinoma (PDAC) are unclear.
CircRNAs were verified by Sanger sequencing. Colony formation, 5-Ethynyl-2'-deoxyuridine (EdU), and Transwell assays were performed to investigate the effect of circBFAR on the proliferation, invasion, and migration of PDAC cells in vitro. RNA pull-down assays were conducted to verify the binding of circBFAR with microRNA miR-34b-5p.
In the present study, we identified a novel circRNA (termed as circBFAR, hsa_circ_0009065) that was upregulated in a 208-case cohort of patients with PDAC. The ectopic expression of circBFAR correlated positively with the tumor-node-metastasis (TNM) stage and was related to poorer prognosis of patients with PDAC. Moreover, circBFAR knockdown dramatically inhibited the proliferation and motility of PDAC cells in vitro and their tumor-promoting and metastasis properties in in vivo models. Mechanistically, circBFAR upregulated mesenchymal-epithelial transition factor (MET) expression via sponging miR-34b-5p. Additionally, circBFAR overexpression increased the expression of MET and activated downstream phosphorylation of Akt (Ser 473) and further activated the MET/PI3K/Akt signaling pathway, which ultimately promoted the progression of PDAC cells. Importantly, application of MET inhibitors could significantly attenuate circBFAR-mediated tumorigenesis in vivo.
Our findings showed that circBFAR plays an important role in the proliferation and metastasis of PDAC, which might be explored as a potential prognostic marker and therapeutic target for PDAC.
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