Interfacial reaction of silver ultra-thin film deposited on interpenetrating polymer network substrate by liquor-phase reduction

The interfacial reaction, metal transformations, and nonmetal bond types of silver ultra-thin film deposited on polyurethane (PU) based interpenetrating polymer networks (IPN) substrate by the liquor-phase reduction at room temperatures were studied by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The IPN substrate was prepared by dip-pulling precursors onto a silicon wafer or a glass plate, followed by solidification at room temperature. The interpenetrate structures of IPN with two crosslinked networks restricted the aggregation of silver during the reduction and deposition. The devised -OH terminal group in PU simplified the determination of reactive site in IPN and reinforced the adhesion between IPN and silver through interfacial reaction. The XPS results, which matched well with the ATR-FTIR results, verified the chemical reactive site of PU in IPN with silver in the oxide state.     

A superconvergent $L^{\infty}$-error estimate of RT1 mixed methods for elliptic control problems with an integral constraint

In this paper, we investigate the superconvergence property of mixed finite element methods for a linear elliptic control problem with an integral constraint. The state and co-state are approximated by the order $k=1$ Raviart-Thomas mixed finite element spaces and the control variable is approximated by piecewise constant functions. A superconvergent approximation of the control variable $u$ will be constructed by a projection of the discrete adjoint state. It is proved that this approximation have convergence order $h^{2}$ in $L^{\infty}$-norm. Finally, a numerical example is given to demonstrate the theoretical results.     

Elliptic reconstruction and a posteriori error estimates for parabolic optimal control problems

In this article, a semidiscrete finite element method for parabolic optimal control problems is investigate. By using elliptic reconstruction, a posteriori error estimates for finite element discretizations of optimal control problem governed by parabolic equations with integral constraints are derived.     

Progress of the key materials for organic solar cells

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecular donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development.     

Study of the 137Cs adsorption performance of ion-eroded cement

For this study, ion-eroded cement was prepared from the cement required for construction of middle- and low-level radioactive waste repositories in caves. The properties for adsorption of ¹³⁷Cs on cement before and after ion erosion were investigated. XRF, XRD, SEM–EDS and BET were used to analyse various cement materials. The effects of reaction time, solid–liquid ratio, initial radioactivity and different ions on adsorption were studied by static batch experiments. When the initial radioactivity was 1114.5 Bq L^?1 and the solid–liquid ratio was 5 g L^?1, the adsorption equilibrium time was 12 h. Adsorption of ¹³⁷Cs on ion-eroded cement was more effective than that on untreated cement. The adsorption process was consistent with the pseudosecond-order kinetic model and the Freundlich isotherm model, and the process involved multilayer chemisorption. This study provides basic research data for construction of a disposal repository.

     

Vanishing viscosity limit for the 3D nonhomogeneous incompressible Navier–Stokes equations with a slip boundary condition

In this paper, we investigate the vanishing viscosity limit for the 3D nonhomogeneous incompressible Navier–Stokes equations with a slip boundary condition. We establish the local well‐posedness of the strong solutions for initial boundary value problems for such systems. Furthermore, the vanishing viscosity limit process is established, and a strong rate of convergence is obtained as the boundary of the domain is flat. In addition, it is needed to add some additional condition for density to match well the boundary condition. Copyright © 2017 John Wiley & Sons, Ltd.     

A Chemosorption Vacuum Pump for a Chemical Oxygen Iodine Laser with CO<Subscript>2</Subscript> Buffer Gases

We present the design and investigation of a novel chemosorption vacuum pump (CSVP) for discharging the exhaust gases of a chemical oxygen-iodine laser system diluted with carbon dioxide (CO₂-COIL). The CSVP comprises two fixed-bed reactors separately filled with CO₂/H₂O and O₂/I₂/Cl₂ adsorbents, which can efficiently chemically absorb the CO₂-COIL exhaust gases at room or higher temperature. We consider the effects of the adsorbents in different specifications and fixed beds of various constructions on the adsorption performance of the CSVP. We develop and study the sealed CO₂-COIL system with the CSVP. We achieve a stable operation with a cumulative duration time of 40 s for four runs and an average output power up to 2.0 kW at a Cl₂ flow rate of ～158 mmol/s and a CO₂ flow rate of 132 mmol/s. The experimental results indicate that the COIL system with the CSVP performs similarly to a conventional COIL with a vacuum tank. Taking into account that the CSVP is free of vibration and noise, avoids air pollution, is easily operated, and has a short preparation time, we believe that the chemosorption vacuum pump is an excellent alternative pump system for a transportable COIL system.     

TiO_2/S_2O_8~(2-)固体超强酸催化长叶烯异构化反应

采用TiO2 S2 O82 -固体超强酸催化长叶烯异构化反应 ,考察了催化剂制备方法及处理催化剂所用的 (NH4 ) 2 S2 O8溶液浓度、催化剂的焙烧温度、用量、反应温度及反应时间等对催化性能的影响 ,得出最佳反应条件。TiO2 S2 O82 -固体超强酸对长叶烯异构化反应具有很高的催化活性和选择性 ,主产物为异长叶烯 ,得率高达约 96%。     

Existence and Upper Semicontinuity of the Attractor for a Singularly Perturbed Navier-Stokes Equation

Suppose Rn, n = 2,3 be a smooth bounded domain, we consider the perturbed Navier-Stokes equationequation ut - ut - u + (u )u + p = F, in ,equationequation div u = 0, in ,equationequation u = 0, on .equation The study of this equation for = 0 has a long and richhistory. In the two-dimensional case, the study is very successful and it iswell known that the solutions of the equation define a C0-semigroupS(t): t 0 inthe space H = PL2() (where P is the projection onto the space ofdivergence-free vector fields) and which has a global attractor A0 on H(see ［1］). But, in the three-dimensional case, things are quitedifference, although some progress has been made recently,there are many problems still open, i.e., the global regularity of thesolutions and the existence of the global attractors (see ［1--7］ andthe references therein). The machanical background ofthe equation in the case of > 0 can be found in ［8］     

塔宝效应在求缺口应力集中系数中的应用

用普通云纹法研究微小弹性变形时,存在着灵敏度较低的问题.本方利用塔宝效应,产生一个不同栅线距的栅.与原栅形成初始云纹,来增加云纹条纹的密度,从而提高了测量精确度.