Overdetermined partial boundary value problems on finite networks

In this study, we define a class of non-self-adjoint boundary value problems on finite networks associated with Schrödinger operators. The novel feature of this study is that no data are prescribed on part of the boundary, whereas both the values of the function and of its normal derivative are given on another part of the boundary. We show that overdetermined partial boundary value problems are crucial for solving inverse boundary value problems on finite networks since they provide the theoretical foundations for the recovery algorithm. We analyze the uniqueness and the existence of solution for overdetermined partial boundary value problems based on the nonsingularity of partial Dirichlet-to-Neumann maps. These maps allow us to determine the value of the solution in the part of the boundary where no data was prescribed. We also execute full conductance recovery for spider networks.     

Size control and catalytic activity of bio-supported palladium nanoparticles

The development of nanoparticles has greatly improved the catalytic properties of metals due to the higher surface to volume ratio of smaller particles. The production of nanoparticles is most commonly based on abiotic processes, but in the search for alternative protocols, bacterial cells have been identified as excellent scaffolds of nanoparticle nucleation, and bacteria have been successfully employed to recover and regenerate platinum group metals from industrial waste. We report on the formation of bio-supported palladium (Pd) nanoparticles on the surface of two bacterial species with distinctly different surfaces: the gram positive Staphylococcus sciuri and the gram negative Cupriavidus necator. We investigated how the type of bacterium and the amount of biomass affected the size and catalytic properties of the nanoparticles formed. By increasing the biomass:Pd ratio, we could produce bio-supported Pd nanoparticles smaller than 10nm in diameter, whereas lower biomass:Pd ratios resulted in particles ranging from few to hundreds of nm. The bio-supported Pd nanoparticle catalytic properties were investigated towards the Suzuki-Miyaura cross coupling reaction and hydrogenation reactions. Surprisingly, the smallest nanoparticles obtained at the highest biomass:Pd ratio showed no reactivity towards the test reactions. The lack of reactivity appears to be caused by thiol groups, which poison the catalyst by binding strongly to Pd. Different treatments intended to liberate particles from the biomass, such as burning or rinsing in acetone, did not re-establish their catalytic activity. Sulphur-free biomaterials should therefore be explored as more suitable scaffolds for Pd(0) nanoparticle formation.     

RECOVERY BASED FINITE ELEMENT METHOD FOR BIHARMONIC EQUATION IN 2D

We design and numerically validate a recovery based linear finite element method for solving the biharmonic equation.The main idea is to replace the gradient operator▽on linear finite element space by G(▽)in the weak formulation of the biharmonic equation,where G is the recovery operator which recovers the piecewise constant function into the linear finite element space.By operator G,Laplace operator△is replaced by▽·G(▽).Furthermore,the boundary condition on normal derivative▽u-n is treated by the boundary penalty method.The explicit matrix expression of the proposed method is also introduced.Numerical examples on the uniform and adaptive meshes are presented to illustrate the correctness and effectiveness of the proposed method.     

回收LNG冷能的新型碳二烃两级膨胀朗肯循环

提出了一种新型的回收LNG冷能的两级膨胀朗肯动力循环,可以乙烯或乙烷作为工质。此工艺流程采用多股流低温板翅式换热器(MSCHE)作为主要设备,使工质两级膨胀并采用回热过程,可以使循环的冷能利用效率得到明显提高。针对此工艺分别以乙烯或乙烷为工质,与LNG直接膨胀结合和不结合,共四种方案采用HYSYS软件进行工艺模拟,并对模拟结果进行了比较和分析,可得出无LNG膨胀的乙烯两级膨胀工艺流程最为合理,其冷能和火用的利用率可以分别达到19.67%和21.75%。     

Modeling of the mass transfer and conduction behavior in electro-electrodialysis with oil/water emulsion as the catholyte

In this paper, a mathematic model has been developed to simulate a modified two-phase electro-electrodialysis (MTPEED) process in which an oil/water (O/W) emulsion is used as the catholyte. Previous results have demonstrated that the process is highly efficient in the recovery of organic acids. The fundamental aspects of this model are expressed by the overall mass transport equation and the total voltage equation. The mass transport equation includes several parameters, such as the electro-migration coefficient, the solute diffusion coefficient, the electro-osmotic coefficient, the concentration-osmotic coefficient as well as the current density and membrane selectivity coefficient. The voltage equation includes the electrode potential, the membrane potential, the solution resistance and the membrane resistance. The extraction equilibrium and the conductivity of the O/W emulsion were experimentally determined and calibrated. The model can predict the lactic acid concentration and the solution volume versus operating time well. In the context of this model, we discuss the operating mode's effect on the MTPEED process and the quantitative effect of some design variables.     

聚苯乙烯负载聚酰胺-胺型螯合树脂对Hg2+的吸附分离性能

以聚苯乙烯负载聚酰胺-胺型螯合树脂为吸附剂,确定了金属离子溶液的pH值及流速;洗脱液的流速.浓度及酸度等最佳柱实验条件,测定了以Na 、Mg2 、Ca2 、Ba2 、Ni2 、Cd2 ,Pb2 、Cu2 、Zn2 等金属离子作为干扰离子时谊吸附荆对Hg2 的回收率.实验结果表明,该树脂对Hg2 具有较高的吸附选择性,从二元金属离子混合液中对Hg2 的回收率达到85.3%以上.     

Quality control in residual solvent analysis: the static headspace gas chromatographic method

 Residual solvent testing of raw materials and drug products constitutes part of a quality control programme. Static headspace gas chromatography (HS/GC) is suggested in current pharmacopoeias as a general tool for residual solvent testing. But the main obstacles to using HS/GC procedures are the absence of performance tests, suitable reference solvents and matrix standards, and reference methods. Harmonized regulations for residual solvent testing allow the use of a cumulative approach to estimate the residual solvent content in drug products. The supplier data may be appropriate. Therefore, in a quality control programme the main accent is put on the definition of specification limits (in accordance with toxicological data, and the influence of residual solvents on the physical properties and stability of the product) and supplier qualification. This paper focuses on two main problems linked to supplier qualification: system performance and matrix effect. HS/GC of a mixture containing solvents of different volatility and polarity is proposed as a performance test. The test can be done in three ways in accordance with the residual solvents characteristics, the test sample solubility and the specification levels required. The use of the test as a diagnostic tool is demonstrated and sources of uncertainty of the recovery determination are discussed. Received: 12 December 1998 · Accepted: 25 January 1999     

Average Width and Optimal Recovery of Some Anisotropic Classes of Smooth Functions Defined on the Euclidean Space R~d

§ 1.Introduction and Main Results　 In[1 ] ,[2 ] ,the authors studied some problems of optimal recovery of functions de-fined on a cube,for a class of functions with partial derivatives of a fixed order havingmoduli of continuity not exceeding a given modules of continuity,and for the unit ballsSHαp in the spaces Hαp satisfying the mixed Holder conditionα,respectively.They ob-tained some weak asymptotic results.　 In[3 ] ,[4 ] and[5] ,Magarill-Il' yaev,Liu and Sun studied some proble…