The ability to capture permeability of fractured porous media plays a significant role in several engineering applications, including reservoir, mining, petroleum and geotechnical engineering. In ...order to solve fluid flow and coupled flow-deformation problems encountered in these engineering applications,both empirical and theoretical models had been proposed in the past few decades. Some of them are simple but still work in certain circumstances; others are complex but also need some modifications to be applicable. Thus, the understanding of state-of-the-art permeability evolution model would help researchers and engineers solve engineering problems through an appropriate approach. This paper summarizes permeability evolution models proposed by earlier and recent researchers with emphasis on their characteristics and limitations.
In this note, adaptive neural network (NN) control is investigated for a class of uncertain nonlinear systems with asymmetric saturation actuators and external disturbances. To handle the effect of ...nonsmooth asymmetric saturation nonlinearity, a Gaussian error function-based continuous differentiable asymmetric saturation model is employed such that the backstepping technique can be used in the control design. The explosion of complexity in traditional backstepping design is avoided using dynamic surface control. Using radial basis function NN, adaptive control is developed to guarantee that all the signals in the closed-loop system are semiglobally uniformly ultimately bounded, and the tracking error converges to a small neighborhood of origin by appropriately choosing design constants. The effectiveness of the proposed control is demonstrated in the simulation study.
Abstract
Background
Osteosarcoma (OS) is the most common malignant bone tumor and has a poor prognosis. The potential involvement of circular RNAs (circRNAs) in OS progression remains unexplored.
...Here, we report that
CircECE1
, a circular RNA derived from human
ECE1
, plays a critical role in energy metabolism in OS.
Methods
The RIP chip sequence assay was performed to confirm
CircECE1
, through overexpression or knockdown of
CircECE1
to verify its function in 143B and U2OS. RNA immunoprecipitation and immunoprecipitation were used to verify
CircECE1
’s regulation of protein c-Myc and co- immunoprecipitation was used to verified the competitive binding relationship between
CircECE1
and SPOP. The influence of
CircECE1
on energy metabolism was evaluated by seahorse experiment, western blot, and immunohistochemistry.
Results
We found that
CircECE1
is highly expressed in OS tissues and cells and that
CircECE1
knockdown suppresses tumor proliferation and metastasis both in vitro and in vivo. Further,
CircECE1
significantly promotes glucose metabolism in OS cells in vitro and in vivo. Mechanistically,
CircECE1
interacts with c-Myc to prevent speckle-type POZ-mediated c-Myc ubiquitination and degradation. C-Myc inhibits thioredoxin binding protein (
TXNIP)
transcription and subsequently activates the Warburg effect.
Conclusions
CircECE1
regulates the Warburg effect through the c-Myc/TXNIP axis. CircECE1 mediated signal transduction plays a important role in OS process and energy metabolism. These findings may identify novel targets for OS molecular therapy.
A unified elastoplastic model for describing the stress–strain behavior of partially saturated collapsible rocks is proposed. The elastic–plastic response due to loading and unloading is captured ...using bounding surface plasticity. The coupling effect of hydraulic and mechanical responses is addressed by applying the effective stress concept. Special attention is paid to the rock–fluid characteristic curve (RFCC), effective stress parameter, and suction hardening. A wide range of saturation degree is considered. The characteristics of mechanical behavior in partially saturated collapsible rocks are captured for all cases considered.
As a subclass of noncoding RNAs, circular RNAs (circRNAs) have been demonstrated to play a critical role in regulating gene expression in eukaryotes. Recent studies have revealed the pivotal ...functions of circRNAs in cancer progression. However, little is known about the role of circTADA2A, also named hsa_circ_0043278, in osteosarcoma (OS).
CircTADA2A was selected from a previously reported circRNA microarray comparing OS cell lines and normal bone cells. QRT-PCR was used to detect the expression of circTADA2A in OS tissue and cell lines. Luciferase reporter, RNA immunoprecipitation (RIP), RNA pull-down and fluorescence in situ hybridization (FISH) assays were performed to confirm the binding of circTADA2A with miR-203a-3p. OS cells were stably transfected with lentiviruses, and Transwell migration, Matrigel invasion, colony formation, proliferation, apoptosis, Western blotting, and in vivo tumorigenesis and metastasis assays were employed to evaluate the roles of circTADA2A, miR-203a-3p and CREB3.
Our findings demonstrated that circTADA2A was highly expressed in both OS tissue and cell lines, and circTADA2A inhibition attenuated the migration, invasion and proliferation of OS cells in vitro as well as tumorigenesis and metastasis in vivo. A mechanistic study revealed that circTADA2A could readily sponge miR-203a-3p to upregulate the expression of CREB3, which was identified as a driver gene in OS. Furthermore, miR-203a-3p inhibition or CREB3 overexpression could reverse the circTADA2A silencing-induced impairment of malignant tumor behavior.
CircTADA2A functions as a tumor promoter in OS to increase malignant tumor behavior through the miR-203a-3p/CREB3 axis, which could be a novel target for OS therapy.
In dealing with the wide voltage range of energy storage components and fuel cell, multimode buck-boost converter (MBBC) serves as a versatile interfacing circuit with multimode operation capability. ...In this article, dynamic performance of MBBC is analyzed with consideration of converter operation under multiple modes, and a digital control design method is proposed for fast transient response. The dynamic analysis considers two influence factors, including "transition mode selection" and "close-loop control design." The influences of different Transition mode have been analyzed with the aid of linear parameter varying system, and a new Transition mode has been proposed for the minimum polytopic working region. In "close-loop control design," the recovery time has been minimized with guaranteed robust stability. Compared with small-signal design method, the proposed method not only ensures large-signal stability across multiple working modes, but also offers new insight for Transition mode selection which is overlooked in existing MBBC dynamic analysis. The designed controller has been applied for three representative transition modes, including the first proposed "double-buck-clamping" mode and comparatively evaluated with existing small-signal PI design method.
The direction-of-arrival (DOA) estimation is predominantly influenced by the antenna’s aperture size. However, space constraints on flight platforms often necessitate the use of antennas with smaller ...apertures and fewer array elements. This inevitably imposes limitations on the DOA estimation’s resolution and degrees of freedom. To address these precision constraints, we introduce an accurate DOA estimation method based on spatial synthetic aperture model. This method adopts a two-stage strategy to ensure both efficiency and precision in DOA estimation. Initially, the orthogonal matching pursuit (OMP) reconstruction algorithm processes the original aperture data, providing a rough estimate of target angles that guides the aircraft’s flight direction. Subsequently, the early estimations merge with the aircraft’s motion space samples, forming equivalent spatially synthesized array samples. The refined angle estimation then employs the OMP-RELAX algorithm. Moreover, with the off-grid issue in mind, we devise an estimation method integrating Bayesian parameter estimation with dictionary sequence refinement. The proposed technique harnesses the spatial synthetic aperture for pinpoint estimation, effectively addressing the challenges of atomic orthogonality and angular off-grid on estimation accuracy. Importantly, the efficiency of deploying sparse reconstruction for angle estimation is bolstered by our phased strategy, eliminating the necessity for fine grid analysis across the entire observation scene. Moreover, the poor estimation accuracy caused by coherent source targets and angular-flickering targets is improved by sparse reconstruction. Through simulation and experiment, we affirm the proposed method’s efficacy in angle estimation. The results indicate that target angle estimation errors are limited to within 1°. Furthermore, we assess the impact of variables such as target state, heading angle, spatial sampling points, and target distance on the estimation accuracy of our method, showcasing its resilience and adaptability.
Li3VO4 is fabricated by a facile hydrothermal method and subsequent annealing treatment. The electrochemical performance and the possible charge/discharge mechanism of the as-prepared Li3VO4 as anode ...for Li-ion battery are firstly studied. Galvanostatic battery testing shows that the Li3VO4 electrode exhibits excellent cycle stability and rate capability. At a current density of 0.25 C, it delivers initial discharge and charge capacity about 624 and 481 mAh g-1, respectively, which maintains of 398 and 396 mAh g-1 after 100 cycles. After 60 cycles at various rates from 0.2 to 4.0 C, the discharge capacity can restore 98% when lowering the charge/discharge rate to 0.2 C. A possible redox reaction mechanism is proposed to interpret the lithiation/delithiation process of Li3VO4 according to experimental observations. The electrochemical reaction kinetic of the Li3VO4 electrode is studied by cyclic voltammetry measurement at various scan rate, which indicates the anodic and cathodic peak currents show linear dependence on the square root of scan rate from 0.3 to 1.0 mV s-1, suggesting a lithium ion diffusion controlled mechanism in the charge/discharge process.
The development of components for terahertz wireless communications networks has become an active and growing research field. However, in most cases these components have been studied using a ...continuous or broadband-pulsed terahertz source, not using a modulated data stream. This limitation may mask important aspects of the performance of the device in a realistic system configuration. We report the characterization of one such device, a frequency multiplexer, using modulated data at rates up to 10 gigabits per second. We also demonstrate simultaneous error-free transmission of two signals at different carrier frequencies, with an aggregate data rate of 50 gigabits per second. We observe that the far-field spatial variation of the bit error rate is different from that of the emitted power, due to a small nonuniformity in the angular detection sensitivity. This is likely to be a common feature of any terahertz communication system in which signals propagate as diffracting beams not omnidirectional broadcasts.There is growing interest in the development of components to facilitate wireless communications in the terahertz but the characterization of these systems involve an unmodulated input. Here the authors demonstrate multiplexing and demultiplexing of data streams in the terahertz range using a real data link.
•Shield tunnel lining damage induced by soil-water inrush is studied.•Numerical simulation matches with field results reasonably.•Strength reduction method have been applied for the consideration of ...soil loss.•Lessons learned from this incident have been presented.
This paper reports a case study on shield tunnel lining damage induced by soil-water inrush occurred in Tianjin Metro Line 1, China through both field monitoring and numerical simulation. This incident was triggered by the non-watertight boring work of thru holes adjacent to the cross passage between the twin tunnels. Under high hydraulic gradient, the seepage-prone weak zone was formed and extended, then the outburst of soil-water slurry was occurred. Measures including plugging engineering cotton, injecting quick-setting cement and welding partition plate of steel segments, had been taken but in vain. The outburst of soil-water slurry induced soil movement around the cross passage, thus leading to the damage of tunnel lining and ground surface settlement. After sealing the water ingress holes, stabilization methods including surface grouting and inside tunnel back grouting were applied. The mechanisms of segment lining damage and the effectiveness of stabilization are investigated through both numerical simulation and field monitoring data analysis. Lessons learned from this incident have been discussed, thus providing reference for potential shield tunnelling under similar engineering conditions.
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