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Printed Circuit Boards (PCBs) are the foundational component of electronic devices, and the detection of PCB defects is essential for ensuring the quality control of electronic products. Aiming at the problem that the existing PCB plug-in solder defect detection algorithms cannot meet the requirements of high precision, low false alarm rate, and high speed at the same time, this paper proposes a method based on spatial convolution pooling and information fusion. Firstly, on the basis of YOLOv3, an attention-guided pyramid structure is used to fuse context information, and multiple convolutions of different size are used to explore richer high-level semantic information; Secondly, a coordinated attention network structure is introduced to calibrate the fused pyramidal feature information, highlighting the important feature channels, and reducing the adverse impact of redundant parameters generated by feature fusion; Finally, the ASPP (Atrous Spatial Pyramid Pooling) structure is implemented in the original Darknet53 backbone feature extraction network to acquire multi-scale feature information of the detection targets. With these improvements, the average detection accuracy of the enhanced network has been elevated from 94.45 to 96.43%. This experiments shows that the improved network is more suitable for PCB plug-in solder defect detection applications. [ABSTRACT FROM AUTHOR]

The identification and quantification of the ecological risks, sources and distribution of heavy metals in purple soils are essential for regional pollution control and management. In this study, geo-accumulation index (Igeo), enrichment factor (EF), pollution index (PI), potential ecological risk index (RI), principal component analysis (PCA) model and geographical detector (GD) were combined to evaluate the status, ecological risk, and sources of heavy metals (HMs) in soils from a typical purple soil areas of Sichuan province. The results showed that the average contents of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in purple soil were 7.77, 0.19, 69.5, 27.9, 0.077, 30.9, 26.5 mg/kg and 76.8 mg/kg, and the Igeo, EF and RI of topsoil Hg and Cd in designated area was the highest, and the average contents of Hg and Cd in topsoil were obviously greater than respective soil background value in Sichuan province and purple soil. The hot spots for the spatial distribution of 8 HMs were mainly focused in the southwest and northeast of the designated area, and there were also significant differences for 8 HMs distribution characteristics in the profile soil. Cu comes from both anthropogenic and natural sources, Zn, Ni and Cr mainly come from natural sources, but As, Pb, Hg and Cd mainly derived from human activities. GD results showed that soil texture (X18), altitude (X4), total nitrogen (TN), clay content (X3), sand content (X2) and silt content (X1) had the greatest explanatory power to 8 HMs spatial differentiation.This study provides a reference for understanding the status and influencing factors of HM pollution in typical purple soil, and lays a theoretical foundation for the environmental treatment of purple soil in China. [ABSTRACT FROM AUTHOR]

The exponential time differencing Runge–Kutta method (ETDRK) developed by Cox and Matthews has proven effective in computing nonlinear partial differential equation. However, it is difficult to prove the unconditional energy stability for third-order or higher ETDRK method. In this paper, we proposed a new third-order ETDRK scheme, ETDRK3, and prove its unconditional energy stability. Combining ETDRK3 with a second-order scheme ETDRK2, we proposed an adaptive ETDRK method(ETDRK32). Furthermore, the numerical simulations for phase problems demonstrate the accuracy, stability and efficiency of adaptive step-size strategy. [ABSTRACT FROM AUTHOR]

Background: Circular RNAs (circRNAs) are key factors in the regulation of cancer progression. However, the role of circRUNX1 in lung adenocarcinoma (LUAD) progression is unclear. Methods: The expression levels of circRUNX1, microRNA (miR)-5195-3p, and high-mobility group protein B3 (HMGB3) were detected by quantitative real-time PCR. Cell proliferation, migration, invasion and apoptosis were analyzed by EdU staining, colony formation assay, transwell assay and flow cytometry. Protein levels were measured using western blot analysis. The interaction between miR-5195-3p and circRUNX1 or HMGB3 was verified by dual-luciferase reporter assay and RIP assay. Animal experiments were performed to investigate the role of circRUNX1 in LUAD tumorigenesis. Results: We found that circRUNX1 was upregulated in LUAD tumor tissues and cells. CircRUNX1 knockdown suppressed LUAD cell proliferation and metastasis, while promoted apoptosis. In terms of mechanism, we found that circRUNX1 could sponge miR-5195-3p, and miR-5195-3p inhibitor abolished the regulation of circRUNX1 knockdown on LUAD cell proliferation, metastasis and apoptosis. In addition, miR-5195-3p could target HMGB3, and HMGB3 overexpression reversed the inhibition effect of miR-5195-3p on LUAD progression. Moreover, circRUNX1 knockdown reduced LUAD tumorigenesis. Conclusion: CircRUNX1 facilitated LUAD proliferation and metastasis by regulating the miR-5195-3p/HMGB3 axis, suggesting that it might be a possible therapeutic target for LUAD. [ABSTRACT FROM AUTHOR]

It is difficult to obtain specific information regarding the trigeminal ganglion (TG), especially pediatric TG. The aim of present study was to determine the parameters of the TG and assist in the neuroablative treatment of trigeminal neuralgia (TN). Thirty-seven sides of cadaver heads that had undergone gross anatomical examination were included, with 29 sides of adults and 8 sides of infants. The distance and angles were measured among 12 points, with nine points adjacent to the TG and three points on the foramen ovale (FO). The three points on FO were represented as three different surgical approaches for TN: posterior FO approach (PFO), lateral FO approach (LFO), and anterior FO approach (AFO). A high similarity was found in pediatric TG. No statistical difference was detected in either the distance or the angles between the 12 points. Statistical difference was found in adult heads in some of the distances, which included PFO to point 5 (17.97 ± 3.35 mm in the left and 15.52 ± 2.28 mm in the right; p = 0.03) and LFO to point 5 and point 8. Moreover, the angle for PFO to point 5 showed a statistically significant difference (60.10 ± 14.02 in the left and 46.63 ± 10.48 in the right; p = 0.01). These findings revealed that surgical neuroablation for patients with TN should be performed more carefully when the PFO or LFO approach is adopted, with a precise preoperative evaluation to avoid corneal complications. Two safety radiofrequency rhizotomy points are also presented to deal with two different kinds of TN. [ABSTRACT FROM AUTHOR]

Human mesenchymal stem cells (hMSCs) possess broad prospects in pre-clinical research. In vitro amplification of hMSCs requires appropriate medium to reach the number of seed cells with clinical significance. However, the uncertainty of the heterologous components of the traditional fetal bovine serum (FBS) culture medium has great safety risks. Moreover, existing commercial hMSCs medium is very expensive, therefore a safer and more optimal hMSCs medium is urgently needed. Accordingly, we developed five components adipose-derived hMSCs (hADMSCs) medium without xenogenic components, named E5 SFM. which is mainly composed of knockout serum replacement (KSR), and additionally four components such as fibroblast growth factor and transferrin. Here, we mainly compared the E5 SFM with traditional FBS-containing medium and a commercial medium by surface markers testing, proliferation assay as well as osteogenic, adipogenic and chondrogenic differentiation assessment. We demonstrated that hADMSCs cultured in the E5 SFM showed similar morphological characteristics and immunophenotypes to those in other media. Notably, cell proliferative capability was similar to that in the commercial medium, but higher than that in the FBS-containing medium and other media. Additionally, their capabilities of adipogenic and osteogenic differentiation were significantly higher than those of other media. Consequently, we concluded that the E5 SFM medium can not only effectively promote cell proliferation of hMSCs, but also has optimal differentiative capacity and clear and simple ingredients. [ABSTRACT FROM AUTHOR]

The organic UVA filter is popularized in sunscreen cosmetics due to the advantages of excellent light stability and high molar extinction coefficient. However, the poor water solubility of organic UV filters has been a common problem. Given that nanoparticles (NPs) can significantly improve the water solubility of organic chemicals. Meanwhile, the excited-state relaxation pathways of NPs might differ from their solution. Here, the NPs of diethylamino hydroxybenzoyl hexyl benzoate (DHHB), a popular organic UVA filter, were prepared by an advanced ultrasonic micro-flow reactor. The surfactant (sodium dodecyl sulfate) was selected as an effective stabilizer to prevent the self-aggregation of the NPs for DHHB. Femtosecond transient ultrafast spectroscopy (fs-TA) and theoretical calculations were utilized to trace and explain the excited-state evolution of DHHB in NPs suspension and its solution. The results reveal that the surfactant-stabilized NPs of DHHB reserve a similarly good performance of ultrafast excited-state relaxation. The stability characterization experiments demonstrate that the strategy of surfactant-stabilized NPs for sunscreen chemicals can maintain its stability and enhance the water solubility of DHHB compared with that of the solution phase. Therefore, the surfactant-stabilized NPs of organic UV filters are an effective method to improve water solubility and keep the stability from aggregation and photoexcitation. [ABSTRACT FROM AUTHOR]

We propose and analyze a first-order in time, second order in space finite difference scheme for the functionalized Cahn-Hilliard (FCH) equation with a logarithmic Flory-Huggins potential. The semi-implicit numerical scheme is designed based on a suitable convex-concave decomposition of the FCH free energy. We prove unique solvability of the numerical algorithm and verify its unconditional energy stability without any restriction on the time step size. Thanks to the singular nature of the logarithmic part in the Flory-Huggins potential near the pure states ± 1 , we establish the so-called positivity-preserving property for the phase function at a theoretic level. As a consequence, the numerical solutions will never reach the singular values ± 1 in the point-wise sense and the fully discrete scheme is well defined at each time step. Next, we present a detailed optimal rate convergence analysis and derive error estimates in l ∞ (0 , T ; L h 2) ∩ l 2 (0 , T ; H h 3) under a linear refinement requirement Δ t ≤ C 1 h . To achieve the goal, a higher order asymptotic expansion (up to the second order temporal and spatial accuracy) based on the Fourier projection is utilized to control the discrete maximum norm of solutions to the numerical scheme. We show that if the exact solution to the continuous problem is strictly separated from the pure states ± 1 , then the numerical solutions can be kept away from ± 1 by a positive distance that is uniform with respect to the size of the time step and the grid. Finally, a few numerical experiments are presented. Convergence test is performed to demonstrate the accuracy and robustness of the proposed numerical scheme. Pearling bifurcation, meandering instability and spinodal decomposition are observed in the numerical simulations. [ABSTRACT FROM AUTHOR]

CO2 immiscible flooding is an environmentally-friendly and effective method to enhance oil recovery in ultra-low permeability reservoirs. A mathematical model of CO2 immiscible flooding was developed, considering the variation in crude oil viscosity and starting pressure gradient in ultra-low permeability reservoirs based on the non-Darcy percolation theory. The mathematical model and numerical simulator were developed in the C++ language to simulate the effects of fluid viscosity, starting pressure gradient, and other physical parameters on the distribution of the oil pressure field, oil saturation field, gas saturation field, oil viscosity field, and oil production. The results showed that the formation pressure and pressure propagation velocity in CO2 immiscible flooding were lower than the findings without considering the starting pressure gradient. The formation oil content saturation and the crude oil formation viscosity were higher after the consideration of the starting pressure gradient. The viscosity of crude oil considering the initiation pressure gradient during the formation was higher than that without this gradient, but the yield was lower than that condition. Our novel mathematical models helped the characterization of seepage resistance, revealed the influence of fluid property changes on seepage, improved the mathematical model of oil seepage in immiscible flooding processes, and guided the improvement of crude oil recovery in immiscible flooding processes. [ABSTRACT FROM AUTHOR]

CO2 flooding can significantly improve the recovery rate, effectively recover crude oil, and has the advantages of energy saving and emission reduction. At present, most domestic researches on CO2 flooding seepage experiments are field tests in actual reservoirs or simulations with reservoir numerical simulators. Although targeted, the promotion is poor. For the characterization of seepage resistance, there are few studies on the variation law of seepage resistance caused by the combined action in the reservoir. To solve this problem, based on the mechanism of CO2, a physical simulation experiment device for CO2 non-miscible flooding production manner is designed. The device adopts two displacement schemes, gas-displacing water and gas-displacing oil, it mainly studies the immiscible gas flooding mechanism and oil displacement characteristics based on factors such as formation dip angle, gas injection position, and gas injection rate. It can provide a more accurate development simulation for the actual field application. By studying the variation law of crude oil viscosity and start-up pressure gradient, the characterization method of seepage resistance gradient affected by these two factors in the seepage process is proposed. The field test is carried out for the natural core of the S oilfield, and the seepage resistance is described more accurately. The results show that the advancing front of the gas drive is an arc, and the advancing speed of the gas drive oil front is slower than that of gas drive water; the greater the dip angle, the higher the displacement efficiency; the higher the gas injection rate is, the higher the early recovery rate is, and the lower the later recovery rate is; oil displacement efficiency is lower than water displacement efficiency; taking the actual core of S oilfield as an example, the mathematical representation method of core start-up pressure gradient in low permeability reservoir is established. [ABSTRACT FROM AUTHOR]

An oil-impregnated porous polyimide (PI) retainer is used in space rolling bearings to improve the lubrication performance, which depends on the release of lubricant from the pores, and therefore is closely related to the pore size. To study the effect of pore size, in this work, PI materials with different pore sizes were prepared by preheating the retainer tube billet during the limit pressing process, and then the friction tests were conducted with the ball-on-ring mode. The results show that the applied load deforms the pores, allowing the lubricant to be squeezed out from the pore; the centrifugal effect induced by rotation also makes the lubricant migrate out of the pore. Therefore, for the same pore sizes, the friction coefficients decrease with the increasing loads and rotation speeds. In addition, it was found that there exists an optimal pore size for the best lubrication properties of porous PI material. Furthermore, the optimal pore size should be larger for lubricants with high viscosity. The microscopic mechanism for lubricant outflow from pores is clarified by molecular dynamic simulations. The insights gained in this study can guide the preparation of oil-impregnated porous retainers under different working conditions. [ABSTRACT FROM AUTHOR]

In this paper, we present the first and second order backward differentiation formulas (BDF1, vBDF1, BDF2 and vBDF2) with finite element method for a class of non-autonomous nonlocal partial differential equations with delay. First, the unique solvability of the numerical schemes is proved. The L 2 upper bound of the numerical solution is given by energy estimation. The convergence analysis is fulfilled for nonlinear delay term, with O (h q + Δ t) order for BDF1 and O (h q + Δ t 2) order for BDF2. The convergence order with respect to the spatial discretization is recovered to an optimal O (h q + 1) order for a kind of specific delay term ψ = ∇ · A (x , t) ∇ u . Asymptotic stability analysis is also given, and it is proved that the numerical solution will approach the stationary solution at an exponential speed. Finally, a few numerical experiments are presented to show the convergence order, asymptotic behavior, and multiple stationary solutions of the numerical solutions. [ABSTRACT FROM AUTHOR]

We propose and analyze a BDF2 scheme with variable time steps for the Cahn–Hilliard equation with a logarithmic Flory–Huggins energy potential. The lumped mass method is adopted in the space discretization to ensure that the proposed scheme is uniquely solvable and positivity-preserving. Especially, a new second order viscous regularization term is added at the discrete level to guarantee the energy dissipation property. Furthermore, the energy stability is derived by a careful estimate under the condition that r ≤ r max . To estimate the spatial and temporal errors separately, a spatially semi-discrete scheme is proposed and a new elliptic projection is introduced, and the super-closeness between this projection and the Ritz projection of the exact solution is attained. Based on the strict separation property of the numerical solution obtained by using the technique of combining the rough and refined error estimates, the convergence analysis in l ∞ (0 , T ; L h 2 (Ω)) norm is established when τ ≤ C h by using the technique of the DOC kernels. Finally, several numerical experiments are carried out to validate the theoretical results. [ABSTRACT FROM AUTHOR]

Failure management plays a significant role in optical networks. It ensures secure operation, mitigates potential risks, and executes proactive protection. Machine learning (ML) is considered to be an extremely powerful technique for performing comprehensive data analysis and complex network management and is widely utilized for failure management in optical networks to revolutionize the conventional manual methods. In this study, the background of failure management is introduced, where typical failure tasks, physical objects, ML algorithms, data sources, and extracted information are illustrated in detail. An overview of the applications of ML in failure management is provided in terms of alarm analysis, failure prediction, failure detection, failure localization, and failure identification. Finally, the future directions on ML for failure management are discussed from the perspective of data, model, task, and emerging techniques. [ABSTRACT FROM AUTHOR]

By increasing the activity and specific properties of the catalyst during oxygen reduction reactions (ORR), we hope to improve fuel cell performance and energy conversion efficiency. Using a single microwave step, the graphene oxide-decorated iron phthalate catalyst (FePcNs@GO) nanocomposites were synthesised. Some analytical techniques were used to validate the morphology and composition of Fe catalyst/graphene (FePcGO) and FePcNs@GO. In an oxygen-saturated environment, we conducted the ORR electrocatalytic studies on the prepared materials. The results demonstrate that when FePcNs@GO is combined with graphene oxide, it exhibits excellent electrochemical properties. In comparison to commercial FePc and 20% Pt/C, the overpotential is significantly lower. Under nitrogen-saturated conditions, the Fe2+/3+ redox form potential in FePcNs@GO exhibits a more positive behaviour, which favours strong interactions between Fe2+ and O2. In this work, we demonstrate that platinum-free catalysts have potential applications in ORR. [ABSTRACT FROM AUTHOR]

In this paper, we propose and analyze a finite difference numerical scheme for the Cahn-Hilliard-Navier-Stokes system, with logarithmic Flory-Huggins energy potential. In the numerical approximation to the singular chemical potential, the logarithmic term and the surface diffusion term are implicitly updated, while an explicit computation is applied to the concave expansive term. Moreover, the convective term in the phase field evolutionary equation is approximated in a semi-implicit manner. Similarly, the fluid momentum equation is computed by a semi-implicit algorithm: implicit treatment for the kinematic diffusion term, explicit update for the pressure gradient, combined with semi-implicit approximations to the fluid convection and the phase field coupled term, respectively. Such a semi-implicit method gives an intermediate velocity field. Subsequently, a Helmholtz projection into the divergence-free vector field yields the velocity vector and the pressure variable at the next time step. This approach decouples the Stokes solver, which in turn drastically improves the numerical efficiency. The positivity-preserving property and the unique solvability of the proposed numerical scheme is theoretically justified, i.e., the phase variable is always between -1 and 1, following the singular nature of the logarithmic term as the phase variable approaches the singular limit values. In addition, an iteration construction technique is applied in the positivity-preserving and unique solvability analysis, motivated by the non-symmetric nature of the fluid convection term. The energy stability of the proposed numerical scheme could be derived by a careful estimate. A few numerical results are presented to validate the robustness of the proposed numerical scheme. [ABSTRACT FROM AUTHOR]

This paper considers an active disturbance rejection problem of a singular time-delay system with unknown external disturbances. By using an equivalent-input-disturbance (EID) technique, an EID estimation is developed to compensate the adverse effect of external disturbance on the system. Moreover, a new criterion for admissible of singular time-delay system is obtained in term of strict linear matrix inequality without equality constraint. And on this basis, a sufficient condition is acquired to pledge the EID-based singular time-delay control system to be admissible. Accordingly, state feedback control gain is obtained via the sufficient condition. Two numerical examples are carried out to demonstrate the feasibility and the validity of our method. [ABSTRACT FROM AUTHOR]

By fully utilizing the capability of the spreading intelligent terminals, crowd spectrum sensing is an efficient and cost-effective framework to realize large-scale and broadband spectrum sensing. However, traditional crowd sensing system relies on a centralized architecture, which not only face severe security and privacy issues, but also may not be able to attract enough users to participate in the sensing tasks due to the lack of effective incentive mechanisms and guaranteed rewards. In this paper, we propose a blockchain-based crowd spectrum sensing framework to achieve secure and privacy-preserving spectrum sensing with guaranteed rewards for participating users. Considering the constraint of the sensing task and the workload of users, the optimal pricing and sensing task allocation scheme under the minimum sensing task constraint is investigated by leveraging Stackelberg game model. We analyze the Nash equilibrium of the sub-games and derive the optimal pricing and sensing task allocation strategy, for both uniform pricing and non-uniform pricing schemes. Simulation results demonstrate the effectiveness of the proposed scheme and it is shown that the scheme can maximize the utility while ensuring the completion of the sensing tasks. [ABSTRACT FROM AUTHOR]

This paper deals with the event triggered filtering problem for a class of delayed discrete-time Markov jump neural networks, where a resilient filter with parameter uncertainties is adopted. The aim of this paper is to design a suitable filter which ensures that the filtering error system is stochastically stable and satisfies a prescribed mixed passivity and H∞ performance. Sufficient conditions for solvability of such a problem are developed. Based on the obtained conditions, an explicit expression of the desired resilient filter is proposed. Finally, an example is presented to show the usefulness of the proposed scheme. [ABSTRACT FROM AUTHOR]

In order to enlarge the size of bulk metallic glasses (BMGs), two Cu36Zr48Al8Ag8 BMGs plates were successfully welded by friction stir welding (FSW) without obvious crystallization. The effect of friction stir welding on microstructure and mechanical properties of the BMGs was investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to evaluate the changes of the crystalline particles in the BMGs. Nanoindentation was applied to analyze the changes of the amorphous matrix. Micro-hardness of the stir zone before and after FSW was tested to explore changes of the mechanical properties. Results show that the original Al3Zr particles in the BMGs were refined and some cavities parallel to the rotating direction of the pin were observed in the amorphous matrix after FSW. Furthermore, micro-hardness of the stirred zone rises approximately 50 Hv compared with the as-cast sample due to structure relaxation of the amorphous matrix. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) has become a research hotspot in recent years. With the increase of smart devices which are connected in IoT, the privacy of IoT has become an important problem. Multi-recipient public key encryption (MRPKE) system plays an important role in protecting the privacy of those smart devices in IoT. At present, the existing ID-MRPKE schemes can only achieve the security in the random oracle model. To enhance the security level, a new ID-MRPKE is constructed by using the programmable hash function from multilinear maps. The security of the novel scheme can be proven in the standard model, instead of the random oracle. Furthermore, based on the k-level Multilinear-maps Decisional Deffie-Hellman (MDDH) assumption, we prove that the proposed scheme has the indistinguishability under the selective multi-identity attack and chosen plaintext attack (IND-sMID-CPA). [ABSTRACT FROM AUTHOR]

As virtual networks services emerge increasingly with higher diversification, the issue of spectrum fragments presents great challenge to the elastic optical networks (EON), especially under heaven services burdens. Aimed to solve this problem, this article proposes a dynamic fragments awareness based virtual network mapping (DFA-VNM) strategy of elastic optical network. In this proposed approach, the dynamic fragments awareness model of it is established, which takes available bandwidth demand and spectrum fragment degree into consideration. Moreover, the dynamic fragments awareness based virtual network mapping strategy makes full advantage of real-time fragments awareness result to conduct virtual network service mapping operation with less fragments and lower blocking rate. Testing results show that the proposed approach is able to improved services supporting ability of EON. [ABSTRACT FROM AUTHOR]

In this article, we present and analyze a finite element numerical scheme for a three-component macromolecular microsphere composite (MMC) hydrogel model, which takes the form of a ternary Cahn–Hilliard-type equation with Flory–Huggins–deGennes energy potential. The numerical approach is based on a convex–concave decomposition of the energy functional in multi-phase space, in which the logarithmic and the nonlinear surface diffusion terms are treated implicitly, while the concave expansive linear terms are explicitly updated. A mass lumped finite element spatial approximation is applied, to ensure the positivity of the phase variables. In turn, a positivity-preserving property can be theoretically justified for the proposed fully discrete numerical scheme. In addition, unconditional energy stability is established as well, which comes from the convexity analysis. Several numerical simulations are carried out to verify the accuracy and positivity-preserving property of the proposed scheme. [ABSTRACT FROM AUTHOR]

3D direct planimetry is increasingly used in clinical practice as a rapid way to measure the mitral valve area (MVA) in patients with rheumatic mitral stenosis (MS) who underwent three-dimensional transesophageal echocardiography (3D-TEE). However, data on its accuracy and reliability are scarce. This study aimed to compare the MVA measurements obtained by 3D direct planimetry to the conventional technique multiplanar reconstruction (MPR) in MS patients using 3D-TEE. We retrospectively included 49 patients with rheumatic MS undergoing clinically-indicated 3D-TEE in the study. We determined the 3D direct planimetry measurements of MVA from the left atria aspect (MVALA) and the left ventricle aspect (MVALV), and compared those with the MPR method (MVAMPR). We also assessed the major and minor diameters of the mitral valve orifice using MPR and 3D direct planimetry. We found an excellent agreement between the MVA measurements obtained by the MPR method and 3D direct planimetry (MVALA and MVALV) [intraclass correlation coefficients (ICC) = 0.951 and 0.950, respectively]. However, the MVAMPR measurements were significantly larger than the MVALA and MVALV (p < 0.001; mean difference: 0.12 ± 0.15 cm2 and 0.11 ± 0.16 cm2, respectively).The inter-observer and intra-observer variability ICC were 0.875 and 0.856 for MVAMPR, 0.982 and 0.984 for MVALA, and 0.988 and 0.986 for MVALV, respectively. The major diameter measured by MPR (1.90 ± 0.42 cm) was significantly larger than that obtained by 3D direct planimetry (1.72 ± 0.35 cm for the LA aspect, p < 0.001; 1.73 ± 0.36 cm for the LV aspect, p < 0.001). The minor diameter measured by MPR (0.96 ± 0.25 cm) did not differ from that derived by 3D direct planimetry (0.94 ± 0.25 cm for the LA aspect, p = 0.07; 0.95 ± 0.27 cm for the LV aspect, p = 0.32). 3D direct planimetry provides highly reproducible measurements of MVA and yields data in excellent agreement with those obtained by the MPR method. The discrepancy between the two techniques may be due to differences in major diameter measurements of the mitral valve orifice. [ABSTRACT FROM AUTHOR]

When cold fluid is injected into low-temperature, low-pressure, low-permeability reservoirs containing wax-bearing heavy oil, cryogenic paraffin deposition and heavy oil condensation will occur, thus damaging the formation. Moreover, the formation pressure coefficient is low and the working fluid flowback efficiency is low, which affects the fracturing stimulation effect. Therefore, an in situ heat/gas clean foam fracturing fluid system is proposed. This system can ensure that conventional fracturing fluid can create fractures and carry proppant in the reservoir, generate heat in situ to avoid cold damage, reduce the viscosity, and improve the fluidity of crude oil. The in situ heat fracturing fluid generates a large amount of inert gas while generating heat, thus forming foam-like fracturing fluid, reducing fluid loss, improving proppant-carrying performance, improving gel-breaking performance, effectively improving crack conductivity, and is clean and environmentally friendly. Based on the improved existing fracturing fluid system, in this paper, a new type of in situ heat fracturing fluid system is proposed, and a system optimization evaluation is conducted through laboratory experiments according to the performance evaluation standard of water-based fracturing fluid. Compared with the traditional in situ heat fracturing fluid system, the fracturing fluid system proposed in this study generates a large amount of inert gas and form foam-like fracturing fluid, reduces fluid loss, enhances the proppant-carrying capacity and gel-breaking performance, improves crack conductivity, the gel without residue and that the gel-breaking liquid is clean and harmless. [ABSTRACT FROM AUTHOR]

In this article we propose the Cahn–Hilliard–Navier–Stokes–Darcy–Boussinesq system that models thermal convection of two-phase flows in a fluid layer overlying a porous medium. Based on operator splitting and pressure stabilization we propose a family of fully decoupled numerical schemes such that the Navier–Stokes equations, the Darcy equations, the heat equation and the Cahn–Hilliard equation are solved independently at each time step, thus significantly reducing the computational cost. We show that the schemes preserve the underlying energy law and hence are unconditionally long-time stable. Numerical results are presented to demonstrate the accuracy and stability of the algorithms. [ABSTRACT FROM AUTHOR]

In this paper, numerical analysis is carried out for a class of history-dependent variational-hemivariational inequalities by arising in contact problems. Three different numerical treatments for temporal discretization are proposed to approximate the continuous model. Fixed-point iteration algorithms are employed to implement the implicit scheme and the convergence is proved with a convergence rate independent of the time step-size and mesh grid-size. A special temporal discretization is introduced for the history-dependent operator, leading to numerical schemes for which the unique solvability and error bounds for the temporally discrete systems can be proved without any restriction on the time step-size. As for spatial approximation, the finite element method is applied and an optimal order error estimate for the linear element solutions is provided under appropriate regularity assumptions. Numerical examples are presented to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

The conation and extrusion techniques were proposed by Bossavit (Math Comput Simul 80:1567–1577, 2010) for constructing (m + 1) -dimensional Whitney forms on prisms/cones from m-dimensional ones defined on the base shape. We combine the conation and extrusion techniques with the 2D polygonal H (div) conforming finite element proposed by Chen and Wang (Math Comput 307:2053–2087, 2017), and construct the lowest-order H 1 , H (curl) and H (div) conforming elements on polygon-based prisms and cones. The elements have optimal approximation rates. Despite of the relatively sophisticated theoretical analysis, the construction itself is easy to implement. As an example, we provide a 100-line Matlab code for evaluating the shape functions of H 1 , H (curl) and H (div) conforming elements as well as their exterior derivatives on polygon-based cones. Note that all convex and some non-convex 3D polyhedra can be divided into polygon-based cones by connecting the vertices with a chosen interior point. Thus our construction also provides composite elements for all such polyhedra. [ABSTRACT FROM AUTHOR]

We present and analyze a uniquely solvable and unconditionally energy stable numerical scheme for the ternary Cahn-Hilliard system, with a polynomial pattern nonlinear free energy expansion. One key difficulty is associated with presence of the three mass components, though a total mass constraint reduces this to two components. Another numerical challenge is to ensure the energy stability for the nonlinear energy functional in the mixed product form, which turns out to be non-convex, non-concave in the three-phase space. To overcome this subtle difficulty, we add a few auxiliary terms to make the combined energy functional convex in the three-phase space, and this, in turn, yields a convex-concave decomposition of the physical energy in the ternary system. Consequently, both the unique solvability and the unconditional energy stability of the proposed numerical scheme are established at a theoretical level. In addition, an optimal rate convergence analysis in the ℓ ∞ (0 , T ; H N - 1) ∩ ℓ 2 (0 , T ; H N 1) norm is provided, with Fourier pseudo-spectral discretization in space, which is the first such result in this field. To deal with the nonlinear implicit equations at each time step, we apply an efficient preconditioned steepest descent (PSD) algorithm. A second order accurate, modified BDF scheme is also discussed. A few numerical results are presented, which confirm the stability and accuracy of the proposed numerical scheme. [ABSTRACT FROM AUTHOR]

Purpose: The goal of the study was to elucidate the structure of a new degradant (1,3′-Dimer), generated in the stability testing of ropinirole extended-release tablets, and the formation mechanism of 1,3′-Dimer and its isomer (3,3′-Dimer). Methods: The strategy of combining LC-PDA/UV-MSn (n = 1, 2) and NMR in conjunction with mechanism-based forced degradation study was employed to identify the structure of the unknown degradant and the formation mechanism of this dimeric degradant as well as its isomer, 3,3′-Dimer. The forced degradation was conducted by treating ropinirole API with formaldehyde under alkaline catalysis. A compatibility study between ropinirole and lactose was also performed. Results: The degradant was isolated from the forced degradation sample and characterized by LC-PDA/UV-MSn as well as NMR measurement. The impurity was identified as a new dimeric degradant of ropinirole connected by a methylene bridge via the 1- and 3′-position of each ropinirole unit (i.e., 1,3′-Dimer of ropinirole), which is an isomer of a known dimeric degradant of ropinirole, namely 3,3′-Dimer. Conclusions: The newly occurred unknown degradant in ropinirole extended-release tablets was elucidated as the methylene-bridged 1,3′-Dimer of ropinirole. Based on the mechanistic study, 1,3′-Dimer and its isomer (3,3′-Dimer) were both formed by the reaction of ropinirole with residual formaldehyde present or formed in lactose, a main excipient of the formulation. [ABSTRACT FROM AUTHOR]

We discuss how to combine exponential time differencing technique with multi-step method to develop higher order in time linear numerical scheme that are energy stable for certain gradient flows with the aid of a generalized viscous damping term. As an example, a stabilized third order in time accurate linear exponential time differencing (ETD) scheme for the epitaxial thin film growth model without slope selection is proposed and analyzed. An artificial stabilizing term A τ 3 ∂ Δ 3 u ∂ t is added to ensure energy stability, with ETD-based multi-step approximations and Fourier pseudo-spectral method applied in the time integral and spatial discretization of the evolution equation, respectively. Long-time energy stability and an ℓ ∞ (0 , T ; ℓ 2) error analysis are provided, based on the energy method. In addition, a few numerical experiments are presented to demonstrate the energy decay and convergence rate. [ABSTRACT FROM AUTHOR]

The use of nectar-providing plants to nourish natural enemies of pest species has become a widely-used approach in conservation biological control to reduce pest damage without the indiscriminate use of insecticides. Choice of plant species is crucial to maximize benefits, but suitable species are yet to be identified for many important crop-pest systems. Here we explored the suitability of three candidate nectar plants for use in brassica vegetables to suppress the globally significant pest, Plutella xylostella L. (Lepidoptera: Plutellidae), using the widely-distributed parasitoid, Cotesia vestalis (Haliday) (Hymenoptera: Braconidae). Volatiles of alyssum (Lobularia maritima (L.) Desv) (Brassicaceae) were attractive to the parasitoid and access to flowering shoots increased adult longevity and realized fecundity of C. vestalis. Moreover, adult diamondback moth derived no benefit from this flower. In contrast, buckwheat (Fagopyrum esculentum Moench) (Polygonaceae), a species widely used in conservation biological control in other systems, increased the longevity and fecundity of both pest and parasitoid, rendering it less suitable. A third plant, heronsbill (Portulaca grandiflora Hook.) (Portulacaceae) denied benefit to the pest and promoted longevity of the parasitoid under no-choice conditions but did not improve fecundity and was repellent to female parasitoids under choice conditions. The contrasting effects of this set of plants illustrate the need to test multiple response variables and effects on both pest and natural enemy when seeking optimal nectar plants for use in a novel conservation biological control system. [ABSTRACT FROM AUTHOR]

This paper reports the preparation of an excellent acetone gas-sensitive material consisting of a Eu3+-decorated α-Fe2O3 microflower (EFM) composite film by a simple hydrothermal and calcination method. For comparison, pure α-Fe2O3 microflowers (PFM) are prepared with the same method. Scanning electron microscopy (SEM) images show that the samples are a loose 3D flower-like structure with many voids surrounded by many thin nanosheets. The structure of the samples was investigated using X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The PFM and EFM gas sensors were systematically tested for gas sensitivity at an optimum temperature of 145 °C. The sensitivity of the EFM gas sensor with 50 ppm of acetone gas was 83, which was up to four times that of the PFM sensitivity (19). The EFM sensor had an extremely fast response time (4 s) and recovery time (38 s). Moreover, the minimum concentration of acetone that we could detect was 0.1 ppm with a response value of 2.1. The enhancement of gas sensitivity was attributed to the high catalytic activity of the Eu3+ additive. [ABSTRACT FROM AUTHOR]

With the increasing demand for high-performance sensors, gas-sensing materials are recognized as one of the core components of gas sensors. Therefore, the development of gas-sensing materials with excellent gas-sensing properties is of great significance. To meet this requirement, we aim to synthesize high-performance 1D gas-sensing materials with new morphologies. In this work, pearl-necklace-shaped In2O3 nanotubes (PINTs) were successfully synthesized by a single-nozzle electrostatic spinning method followed by calcination. The nanostructure and formaldehyde gas-sensing properties of PINTs were compared with those of In2O3 nanotubes (INTs) and In2O3 nanofibres (INFs), and the morphologies and phases of PINTs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The SEM images clearly show that PINTs have a unique tubular structure that looks like a string of pearls. The formaldehyde gas-sensing characteristics of the sensors based on INFs, INTs and PINTs were investigated. All gas sensitivity measurements were performed at an optimum operating temperature of 220 °C. The results revealed that the sensors based on PINTs showed the greatest response to formaldehyde gas (38.3/100 ppm) compared with the sensors based on INTs (18.5/100 ppm) and INFs (9.0/100 ppm). Sensors with PINTs were found to have shorter response and recovery times (6 s and 16 s) than those of INTs (8 s and 22 s) and INFs (8 s and 27 s). The enhanced gas-sensing properties may be attributed to the novel nanostructure of PINTs. Furthermore, the sensors based on PINTs have good linearity, stability, repeatability and selectivity. These properties make PINTs ideal gas-sensing materials for use in sensors for formaldehyde detection. [ABSTRACT FROM AUTHOR]

In Li et al. (J Sci Comput 76(3):1905–1937, 2018), a temporal second-order mixed finite element scheme has been proposed for the thin film epitaxial growth model without slope selection. Using the super-convergence theory in a regular rectangular mesh, the authors of Li et al. (2018) proved an optimal O (h q + 1 + τ 2) convergence. However, in a quasi-uniform triangulation mesh setting, only a sub-optimal convergence rate O (h q + τ 2) is proved, while numerical results indicated an optimal O (h q + 1 + τ 2) convergence when the exact solution has H q + 1 regularity in space. Here h and τ are the discretization sizes in space and time, respectively, and q ≥ 1 is the degree of the polynomial in the spatial discretization. In this paper, we provide a theoretical proof of the optimal convergence rate. The main difficulty lies in how to treat a nonlinear term ∇ u 1 + | ∇ u | 2 . We solve this by using a discrete Laplacian operator - Δ h and some uncommon techniques in the analysis. Numerical results are also presented to demonstrate the (q + 1) -order convergence of the spatial approximation. [ABSTRACT FROM AUTHOR]

Security against selective opening attack (SOA) for receivers requires that in a multi-user setting, even if an adversary has access to all ciphertexts, and adaptively corrupts some fraction of the users to obtain the decryption keys corresponding to some of the ciphertexts, the remaining (potentially related) ciphertexts retain their privacy. In this paper, we study simulation-based selective opening security for receivers of public key encryption (PKE) schemes under chosen-ciphertext attacks (RSIM-SO-CCA). Concretely, we first show that some known PKE schemes meet RSIM-SO-CCA security. Then, we introduce the notion of master-key SOA security for identity-based encryption (IBE), and extend the Canetti–Halevi–Katz transformation to show generic PKE constructions achieving RSIM-SO-CCA security. Finally, we show how to construct an IBE scheme achieving master-key SOA security. [ABSTRACT FROM AUTHOR]

The Kaixinling coal is located in the eastern part of the North Qiangtang Basin, which were the important coal resources in Tibetan Plateau. A total of thirty coal samples were collected from the Kaixinling area to determine the concentrations, distribution patterns, occurrences and origins of platinum group elements (PGEs) in the Permian coal. The total contents of PGEs are low ranging from 0.56 to 1.89 ng/g with a weighed mean value of 1.21 ng/g. The contents in Os exhibit considerably positive anomaly compare to the Upper Continental Crust and the ordinary Chinese coal. The individual PGEs in coal samples from the Kaixinling area exhibit various modes of occurrence. Pd and Pt are mainly concentrated in clay minerals and P-bearing minerals. Ir is probably present in clay minerals and partly controlled by other Fe-bearing and P-bearing minerals. Os is associated with organic matter and partly related to calcite. Three possible origins of PGEs were identified in coal seams in the Kaixinling area. Pd, Pt and Ir are mainly terrigenous inputs. Rh and Ru are derived from mixed sources (seawater and terrigenous supply), while Os is mainly derived from seawater. [ABSTRACT FROM AUTHOR]

An analytical method based on sugaring-out assisted liquid-liquid extraction (SULLE) and HPLC-fluorescence detection has been developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) in royal jelly. Experimental parameters of SULLE including the extraction solvent, amount of phase separation agent, initial concentration of acetonitrile (ACN), and sample size were investigated. The optimal SULLE procedure involves 0.3 g sample extracted by 2 mL ACN-water mixture (50%, v/v), followed by phase separation with the addition of 0.4 g glucose. The obtained extract was injected into the reversed-phase HPLC system without clean-up step. The chromatography separation of BPA and BPB from royal jelly matrix was achieved in the mobile phase composed of 40% ACN and 60% water with isocratic elution at 1.0 mL/min. Limits of quantification for BPA and BPB were 40 μg/kg and 45 μg/kg, respectively, and limits of detection for BPA and BPB were 16 μg/kg and 18 μg/kg, respectively. Average recoveries of BPA and BPB at three spiked levels were in the range of 88.32~93.59% and 95.14~97.48%, respectively. Precision expressed as relative standard deviations (RSDs) in the interday and intraday analysis were all lower than 5%. The developed method was applied to the analysis of ten commercial and eight raw royal jelly samples. Results indicated that none of BPA and BPB were detected in these 18 samples. The proposed method is simple, fast, and sensitive, and could be used for the monitoring of BPA and BPB contamination in royal jelly. [ABSTRACT FROM AUTHOR]

Key message: We provided a chromosome-length assembly of B. nigra and show the comprehensive chromosome-scale variations among Brassica genomes.Abstract: Chromosome-level assembly of the Brassica species, which include many important crops, is essential for the agricultural and evolutionary studies. While the present B. nigra chromosomes was connected with genetic map of B. juncea, hindering the comparative analysis of the B chromosomes. Here we present a chromosome-length B. nigra assembly constructed with Hi-C connections and its variations on chromosome level compared with other Brassica species. We produced an assembly of 484 Mb annotated with 51,829 genes, of which 393 Mb were anchored onto 8 chromosomes, taking 81.26% of the assembly. Comparison of the B chromosomes shows high concordance of the two B. nigra assemblies and reveals comprehensive variations of the B chromosomes after polyploidization and gene loss in syntenic regions. Chromosome blocks with variations have lower gene density and higher TE content. Furthermore, we compared the chromosomes of the three major Brassica diploids, which showed that most of the variations between B and A/C had completed before A/C divergence and there are more variations on C chromosomes after their divergence. In summary, our work presents a chromosome-length assembly of B. nigra and comprehensive comparative analysis of the Brassica chromosomes, which provides a useful reference for other studies and comprehensive information of Brassica chromosome evolution. [ABSTRACT FROM AUTHOR]

In this paper we present a second order accurate, energy stable numerical scheme for the epitaxial thin film model without slope selection, with a mixed finite element approximation in space. In particular, an explicit treatment of the nonlinear term, ∇u1+|∇u|2, greatly simplifies the computational effort; only one linear equation with constant coefficients needs to be solved at each time step. Meanwhile, a second order Douglas-Dupont regularization term, AτΔ2(un+1-un), is added in the numerical scheme, so that an unconditional long time energy stability is assured. In turn, we perform an ℓ∞(0,T;L2) convergence analysis for the proposed scheme, with an O(τ2+hq) error estimate derived. In addition, an optimal convergence analysis is provided for the nonlinear term using Qq finite elements, which shows that the spatial convergence order can be improved to q+1 on regular rectangular mesh. A few numerical experiments are presented, which confirms the efficiency and accuracy of the proposed second order numerical scheme. [ABSTRACT FROM AUTHOR]

Nonalcoholic fatty liver disease (NAFLD) currently represents the most common hepatic disease worldwide and is closely linked to cardiovascular disease, obesity and diabetes mellitus. This study aimed to investigate NAFLD and its influence on different monocyte subpopulations to determine the presence of significant associations. A total of 3 monocyte subpopulations were investigated, i.e. classical (CD14++CD16−), intermediate (CD14++CD16+) and non-classical (CD14+CD16++). Of the participants 261 were included in this study (n = 53 with NAFLD, n = 208 controls). Ultrasonography was used to diagnose NAFLD and exclude other morphologic causes of liver diseases and other tests (including medical history inquiries and detection of hepatitis virus) were performed to exclude other causes of parenchymal liver disease. Classical inflammatory and metabolic-related NAFLD biomarkers were also determined. In contrast to the healthy control group, the intermediate monocyte fraction was increased in NAFLD patients (p = 0.032), while the classical monocyte fraction was decreased (p = 0.025). Intermediate monocyte fraction, body mass index (BMI) and tumor necrosis factor alpha (TNF-α) were independent risk factors for NAFLD. Classical, non-classical and intermediate monocytes fraction were strongly associated with age, triglyceride, and waist circumference. This study suggests that the intermediate monocyte fraction in peripheral blood is likely related to the aggravation of NAFLD. [ABSTRACT FROM AUTHOR]

In this paper, we show that there is a $$\frac{5}{2}\ell \cdot \ln (1+k)$$ -competitive randomized algorithm for the k-sever problem on weighted Hierarchically Separated Trees (HSTs) with depth $$\ell $$ when $$n=k+1$$ where n is the number of points in the metric space, which improved previous best competitive ratio $$12 \ell \ln (1+4\ell (1+k))$$ by Bansal et al. (FOCS, pp 267-276, 2011). [ABSTRACT FROM AUTHOR]

We propose and analyze two novel decoupled numerical schemes for solving the Cahn-Hilliard-Stokes-Darcy (CHSD) model for two-phase flows in karstic geometry. In the first numerical scheme, we explore a fractional step method (operator splitting) to decouple the phase-field (Cahn-Hilliard equation) from the velocity field (Stokes-Darcy fluid equations). To further decouple the Stokes-Darcy system, we introduce a first order pressure stabilization term in the Darcy solver in the second numerical scheme so that the Stokes system is decoupled from the Darcy system and hence the CHSD system can be solved in a fully decoupled manner. We show that both decoupled numerical schemes are uniquely solvable, energy stable, and mass conservative. Ample numerical results are presented to demonstrate the accuracy and efficiency of our schemes. [ABSTRACT FROM AUTHOR]

We present and analyze a mixed finite element numerical scheme for the Cahn-Hilliard-Hele-Shaw equation, a modified Cahn-Hilliard equation coupled with the Darcy flow law. This numerical scheme was first reported in Feng and Wise (SIAM J Numer Anal 50:1320-1343, 2012), with the weak convergence to a weak solution proven. In this article, we provide an optimal rate error analysis. A convex splitting approach is taken in the temporal discretization, which in turn leads to the unique solvability and unconditional energy stability. Instead of the more standard $$\ell ^\infty (0,T;L^2) \cap \ell ^2 (0,T; H^2)$$ error estimate, we perform a discrete $$\ell ^\infty (0,T; H^1) \cap \ell ^2 (0,T; H^3 )$$ error estimate for the phase variable, through an $$L^2$$ inner product with the numerical error function associated with the chemical potential. As a result, an unconditional convergence (for the time step $$\tau $$ in terms of the spatial resolution h) is derived. The nonlinear analysis is accomplished with the help of a discrete Gagliardo-Nirenberg type inequality in the finite element space, gotten by introducing a discrete Laplacian $$\Delta _h$$ of the numerical solution, such that $$\Delta _h \phi \in S_h$$ , for every $$\phi \in S_h$$ , where $$S_h$$ is the finite element space. [ABSTRACT FROM AUTHOR]

Human gait recognition, an active research topic in computer vision, is generally based on data obtained from images/videos. We applied computer vision technology to classify pathology-related changes in gait in young children using a foot-pressure database collected using the GAITRite walkway system. As foot positioning changes with children's development, we also investigated the possibility of age estimation based on this data. Our results demonstrate that the data collected by the GAITRite system can be used for normal/pathological gait classification. Combining age information and normal/pathological gait classification increases the accuracy of the classifier. This novel approach could support the development of an accurate, real-time, and economic measure of gait abnormalities in children, able to provide important feedback to clinicians regarding the effect of rehabilitation interventions, and to support targeted treatment modifications. [ABSTRACT FROM AUTHOR]

A third-order in time numerical IMEX-type algorithm for the Stokes-Darcy system for flows in fluid saturated karst aquifers is proposed and analyzed. A novel third-order Adams-Moulton scheme is used for the discretization of the dissipative term whereas a third-order explicit Adams-Bashforth scheme is used for the time discretization of the interface term that couples the Stokes and Darcy components. The scheme is efficient in the sense that one needs to solve, at each time step, decoupled Stokes and Darcy problems. Therefore, legacy Stokes and Darcy solvers can be applied in parallel. The scheme is also unconditionally stable and, with a mild time-step restriction, long-time accurate in the sense that the error is bounded uniformly in time. Numerical experiments are used to illustrate the theoretical results. To the authors' knowledge, the novel algorithm is the first third-order accurate numerical scheme for the Stokes-Darcy system possessing its favorable efficiency, stability, and accuracy properties. [ABSTRACT FROM AUTHOR]