Search

This paper opens a series of papers focusing on boundary conditions for kinetic theory based models. As a start, we consider the lattice Boltzmann models and construct certain parametrized single-node second-order boundary schemes. For such models, the construction is quite universal and simple, it does not involve concrete collision terms but uses the half-way bounce-back rule as a central step. The obtained schemes have good stability thanks to convex combinations. The second-order accuracy of the schemes is justified for some widely used collision terms. As a byproduct, we propose a sufficient condition on the collision terms to ensure the second-order accuracy of the half-way bounce-back rule. The accuracy and stability of several specific schemes are numerically validated through both two- and three-dimensional flow problems. [ABSTRACT FROM AUTHOR]

A universal mold casting approach for the preparation of cation-exchange membranes (CEMs) and anion-exchange membranes (AEMs) with ultrahigh ion-exchange capacities (IECs) is developed based on in situ cross-linking polymerization of acrylic acid (AA) and 2-vinylpyridine (2VP), respectively. This new method produced ultrahigh IECs of 7.88 mequiv g-1 for CEM and 6.27 mequiv g-1 for AEM, which are 8.8 and 7.0 times that (0.89 mequiv g-1) of Nafion 117, respectively. Also, the prepared membranes demonstrate excellent thermal and chemical stability and acceptable conductivity. As a consequence, the membranes show relatively high performance for ion-exchange application and methanol barrier, exhibiting ion permeabilities of 2.06 × 10-7 cm² s-1 for Na+, 2.57 × 10-7 cm² s-1 for Ca2+, 1.45 × 10-7 cm² s-1 for Cu2+ regarding CEMs, and 7.72 × 10-7 cm² s-1 for methanol regarding AEMs. These results indicate that the CEMs and AEMs fabricated from the universal mold casting approach are promising candidates for targeting ultrahigh ion-exchange capacity membranes. [ABSTRACT FROM AUTHOR]

Drug resistance to cisplatin with continuous drug treatment is one of the most common causes of chemotherapy failure in hepatic carcinoma. Accumulating evidence suggests that WEE1 G2 checkpoint kinase (WEE1) is involved in cisplatin resistance, which has been demonstrated to correlate with cancer initiation and progression. However, the role and molecular mechanism of WEE1 in the drug resistance of hepatic cancer remains unclear. In the present study, using the WEE-knockdown hepatic cancer cell line HepG2/DDP, the role of WEE1 and its molecular mechanism were investigated. It was demonstrated that silencing WEE1 expression resulted in an increased cisplatin sensitivity of HepG2/DDP, in addition to an increased rate of apoptosis and intracellular concentration of rhodamine 123. The expression levels of P-gp, MDR1, MRP1, LRP, BCL-2, survivin and GST in WEE1-silenced HepG2/DDP cells were significantly reduced, and phosphorylation levels of MEK and ERK were significantly downregulated. The results demonstrated that WEE1 negatively regulated the multidrug resistance potential of human hepatic cancer cells by modulating the expression of relevant drug resistance genes and the activity of the MEK/ERK pathway. Therefore, WEE1 may be a monitoring bio-marker for drug resistance, and a therapeutic target in hepatic cancer. [ABSTRACT FROM AUTHOR]

A one-potsynthetic methodology for fabricating stimuli-responsivehemicellulose-based hydrogels was developed that consists of the insitu formation of magnetic iron oxide (Fe3O4) nanoparticles during the covalent cross-linking of O-acetyl-galactoglucomannan(AcGGM). The Fe3O4nanoparticle content controlledthe thermal stability, macrostructure, swelling behavior, and magnetizationof the hybrid hydrogels. In addition, the magnetic field-responsivehemicellulose hydrogels (MFRHHs) exhibited excellent adsorption andcontrolled release profiles with bovine serum albumin (BSA) as themodel drug. Therefore, the MFRHHs have great potential to be utilizedin the biomedical field for tissue engineering applications, controlleddrug delivery, and magnetically assisted bioseparation. Magnetic field-responsivehemicellulose hydrogels, prepared using a straightforward one-stepprocess, expand the applications of biomass-derived polysaccharidesby combining the renewability of hemicellulose and the magnetism ofFe3O4nanoparticles. [ABSTRACT FROM AUTHOR]

Drought is the leading cause of low and unstable wheat yield in dryland. The field experiment was performed from 2009 to 2017 in the eastern part of Loess Plateau, China, to study the effect of tillage (deep ploughing, DP and no-tillage, NT) and seasonal variation in precipitation on soil moisture and root traits and grain yield of wheat. In dry seasons, soil water content, root length surface density (RLSD), and root diameter peaked at 60 cm depth, but in the normal/wet seasons, peaked at 40 cm depth. The reduction of RLSD at anthesis by drought was 44% under NT and 29% with DP, while the reduction in above-ground dry weight was 67% under NT and 56% under DP. More soil water was depleted from the deep soil layer (80-100 cm depth) than that in the shallow layer (20-60 cm depth) from jointing in the dry seasons, and from anthesis in the normal/wet seasons. The higher amount of effective in-seasonal rainfall in the dry seasons increased RLSD at anthesis by 44% with NT and 21% with DP and increased grain yield by 24.1% under NT and 14.2% under DP. The average grain yield in the dry seasons was 28–41% lower than in the normal/wet seasons. The average water use efficiency (WUE) in the dry seasons was 42–54% lower than that in the normal/wet seasons. WUE with DP was 32% higher than that with NT in the dry seasons, while it was 15% higher than that with NT in the normal/wet seasons. The average contribution rates of soil water content at sowing to grain yield under DP and NT were 23–25% in the dry seasons, and 52–53% in the normal/wet seasons. Thus, deep ploughing in summer fallow should be adopted for high water storage and yield stability. • Deep ploughing in summer fallow increases soil water and yield relative to no tillage. • Soil water at sowing contributes to 24% yield in dry seasons, and 52% in normal/wet seasons. • Root systems grow 20 cm deeper in dry seasons than in normal/wet seasons. • More soil water is depleted from 80-100 cm depth in the dry seasons. • Root length surface density reduced by drought at anthesis is lower than above-ground dry weight. [ABSTRACT FROM AUTHOR]

Nowadays the demand for identifying the authenticity of an image is much increased since advanced image editing software packages are widely used. Region duplication forgery is one of the most common and immediate tampering attacks which are frequently used. Several methods to expose this forgery have been developed to detect and locate the tampered region, while most methods do fail when the duplicated region undergoes rotation or flipping before being pasted. In this paper, an efficient method based on Harris feature points and local binary patterns is proposed. First, the image is filtered with a pixelwise adaptive Wiener method, and then dense Harris feature points are employed in order to obtain a sufficient number of feature points withapproximately uniform distribution. Feature vectors for a circle patch around each feature point are extracted using local binary pattern operators, and the similar Harris points are matched based on their representation feature vectors using the BBF algorithm. Finally, RANSAC algorithm is employed to eliminate the possible erroneous matches. Experiment results demonstrate that the proposed method can effectively detect region duplication forgery, even when an imagewas distorted by rotation, flipping, blurring, AWGN, JPEGcompression, and theirmixed operations, especially resistant to the forgery with the flat area of little visual structures. [ABSTRACT FROM AUTHOR]

Paper and plastic bags have been mainly used in fruit bagging of pineapple production. However, they are often discarded as agricultural wastes after harvest of pineapple fruit and threaten environment. In this study, effects of white non-woven fabric bag, expandable polyethylene bag, black plastic bag and kraft paper bag on fruit quality of pineapple cv. 'MD-2' were investigated. Results showed that fruits with fruit bagging showed no sunburn. When expandable polyethylene bag was used, fruits of pineapple cv. 'MD-2' showed better external qualities, nutrition qualities and texture properties. Expandable polyethylene bag made of degradable and recyclable materials could be recommended as a promising practice to reduce agricultural waste in pineapple production. [ABSTRACT FROM AUTHOR]

Well-defined block copolymers, poly(ethylene glycol) methyl ether-b-poly(styrene) (mPEG-b-PS), in which the PS blocks had different molecular weights, were synthesized by atom-transfer radical polymerization (ATRP) and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The block copolymers were then used as amphiphilic additives to modify polyethersulfone (PES) hollow fiber membranes to improve the antifouling property. Static contact angle measurement indicated the increase of the membrane surface hydrophilicity, and scanning electron micrograph (SEM) suggested that the modified membranes preserved asymmetric structure. Protein ultrafiltration experiments showed that the antifouling ability of the modified membranes enhanced. After three cycles of BSA solution (1.0 mg/mL) ultrafiltration and three times of hydraulic cleaning, the water flux recovery ratios (FRR) of the mPEG-b-PS modified membranes were still as high as 85.6%. The hydrophilic modification with mPEG-b-PS copolymers is a good method to improve the antifouling property of PES hollow fiber membranes. [ABSTRACT FROM AUTHOR]

Ge/Ag/Ni and AuGe/Ni/Au Ohmic contacts on InAlAs/InGaAs/InP high electron mobility transistors with excellent contact resistance of 0.07 Ω mm were obtained after annealing at 425 and 265 °C, respectively. The Ag-based contacts have a large processing window of >130 °C. Structural analyses confirm that Ag and Au protrusions created during annealing effectively linked the two-dimensional electron gas layer with the metal contacts to produce excellent Ohmic characteristics. The formation of liquid AuGe eutectic phase in AuGe/Ni/Au at 300 °C is believed to cause overannealing. The eutectic temperature of Ag–Ge is ∼300 °C higher leading to a higher optimum annealing temperature and a wider processing window for the Ge/Ag/Ni contacts. [ABSTRACT FROM AUTHOR]

A relaxation-rate formula is presented for the entropic lattice Boltzmann model (ELBM) — a discrete kinetic theory for hydrodynamics. The simple formula not only guarantees the discrete time H-theorem but also gives full consideration to the consistency with hydrodynamics. The relaxation rate calculated with the formula effectively characterizes the drastic changes of the flow fields. By using this formula, the computational cost of the ELBM is significantly reduced and the model now can be efficiently used for a broad range of applications including high Reynolds number flows. [ABSTRACT FROM AUTHOR]

In this paper, we target two basic issues residing in some modified lattice kinetic schemes for the Navier-Stokes (NS) equations coupled with convection-diffusion equations (CDEs). First, a lattice Boltzmann (LB) model motivated by the lattice kinetic scheme (LKS) is presented for the NS equations coupled with CDEs. Due to the nonequilibrium schemes for the gradient terms contained in the equilibria as well as the discrete source term, the collision process of the present model can be implemented locally in both time and space. The Chapman-Enskog analysis shows that the macroscopic equations can be correctly recovered from the present model without additional assumptions. Second, we prove that the present modified LKS model, though written in the Bhatnagar-Gross-Krook (BGK) form, has two relaxation rates essentially. Based on this theoretical result, the modified lattice kinetic schemes in the literature should not be grouped as the BGK model, and the better numerical stability is intrinsically attributed to the adjustment of their two relaxation rates. Several benchmark thermal flow problems are simulated to validate the present model and the local nonequilibrium schemes for the shear rate and temperature gradient. The accuracy of the present model as well as its better numerical stability compared with the BGK model are verified, which supports our theoretical results. In addition, we also demonstrate that the regularized LB (RLB) model has two relaxation times as the present LKS model. [ABSTRACT FROM AUTHOR]

In this work, we present an alternative derivation of the Navier-Stokes equations from Bhatnagar-Gross-Krook models of the lattice Boltzmann method with diffusive scaling. This derivation is based on the Maxwell iteration and can expose certain important features of the lattice Boltzmann solutions. Moreover, it will be seen to be much more straightforward and logically clearer than the existing approaches including the Chapman-Enskog expansion. [ABSTRACT FROM AUTHOR]

We propose using the Maxwell iteration to derive the hydrodynamic equations from the lattice Boltzmann equation (LBE) with an external forcing term. The proposed methodology differs from existing approaches in several aspects. First, it need not explicitly introduce multiple-timescales or the Knudsen number, both of which are required in the Chapman-Enskog analysis. Second, it need not use the Hilbert expansion of the hydrodynamic variables, which is necessary in the asymptotic analysis of the LBE. The proposed methodology assumes the acoustic scaling (or the convective scaling) δt~δx, thus δt is the only expansion parameter in the analysis of the LBE system, and it leads to the Navier-Stokes equations in compressible form. The forcing density derived in this work can reproduce existing forcing schemes by adjusting appropriate parameters. The proposed methodology also analyzes the numerical accuracy of the LBE. In particular, it shows the Mach number Ma should scale as O(δ1/3t) to maintain the truncation errors due to Ma and δt in balance when δt→0, so that the LBE can converge to the expected hydrodynamic equations effectively and efficiently. [ABSTRACT FROM AUTHOR]

A peer-to-peer (P2P)-based EAST Data System is being designed to provide data acquisition and analysis support for the EAST superconducting tokamak. Instead of transferring data to the servers, all collected data are stored in the data acquisition subsystems locally and the PC clients can access the raw data directly using the P2P architecture. Both online and offline systems are based on Napster-like P2P architecture. This allows the peer (PC) to act both as a client and as a server. A simulation-based method and a steady-state operational analysis technique are used for performance evaluation. These analyses show that the P2P technique can significantly reduce the completion time of raw data display and real-time processing on the online system, and raise the workload capacity and reduce the delay on the offline system. [ABSTRACT FROM AUTHOR]

Solution pH is an important factor in the adsorptive behavior of ionizable dyes in the chemical and biotechnology industries. In this study, novel pH-responsive zwitterionic hydrogels were prepared by the copolymerization of acrylic acid and methylacryloyloxyethyl trimethylammonium chloride. The results indicated that the hydrogels showed bidirectionally pH-responsive behaviors: the swelling ratio was small in neutral pH value and increased with the increase or decrease of pH values. Meanwhile, the selective adsorption capacities of the hydrogels for anionic or cationic dyes could be controlled by adjusting the pH values. The hydrogels might be applied in many fields, such as adsorption and separation and water treatment. [ABSTRACT FROM AUTHOR]