流动注射分析法测定废水中的氰化物

建立流动注射分析法测定工业废水中氰化物浓度的方法。水样及试剂在蠕动泵的作用下进入管道,先后经过蒸馏模块与化学模块,最后进入检测模块得出系统处理后的数据。通过对实际样品和标准样品的分析得出该方法的检出限为1.55μg/L,相对误差小于5%。氰化物质量浓度在0~500μg/L范围内与信号值呈良好的线性关系,线性相关系数r2=0.999 9。测定结果的相对标准差为0.1%~3%(n=4),加标回收率为93.3%~102.0%。该方法实现了自动进样、在线蒸馏,具有分析速率快、试剂耗量少等优点,可用于水和废水中总氰化物的测定。     

REGULARITIES AND SINGULARITIES OF THE ENERGY MINIMIZERS OF THE HEISENBERG GROUP TARGETS

In this paper, the properties of the maps for the Heisenberg group targets are studied. For u∈W1,α(Ω, Hm), some Poincare type inequalities are proved. For the energy minimizers, the ∈-regularity theorems and the singularity theorems are obtained.     

Bifurcation dynamics of the modified physiological model of artificial pancreas with insulin secretion delay

In this paper, we modify the original physiological model of artificial pancreas by introducing the insulin secretion time delay. The non-resonant double Hopf bifurcation is analyzed by the Center Manifold Theorem and Normal Form Method. Numerical results supporting the theoretical analysis are presented in some typical parameter regions. It is shown that the critical value of technological delay and the area of death island of the non-resonant double Hopf bifurcation in the modified model are far less than those in the original model. This implies that when the secretion delay appears, the smaller technological delay can induce the double Hopf bifurcation. In addition, the region IV with complex coexisting bi-stability also decreases sharply. Furthermore, the rich dynamics such as various period, quasi-period and chaotic behaviors are found when some key parameters are changed. The obtained results can have important theoretical guidance for the diagnosis and treatment of diabetes patients.     

Synthesis of Ag/AgCl-mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coli

Simple aqueous solution-based chemical methods have been developed for the synthesis of Ag/AgCl nanoparticle-mesoporous silica nanocomposites. Ag loading in the mesoporous silica was accomplished using a wet-impregnation method. The AgCl-mesoporous silica nanocomposite material(AgCl-mSi) was synthesized by using a 'one pot' method. Synthesized materials were characterized using X-ray diffraction,N2 adsorption-desorption analysis and high-resolution transmission electron microscopy. Antibacterial activity of...     

Shape and size effects of ceria nanoparticles on the impact strength of ceria/epoxy resin composites

Ceria nanoparticles with various shapes (rods, cubes, and plates) and sizes were controllably synthesized and then introduced into epoxy resin. Subsequently, we investigated correlations between the shape and size of ceria nanostructures and the mechanical performance of composites. The samples were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Compared with commercial ceria filled composites, the composites made with morphology-controlled ceria nano...     

Preparation and activity evaluation of NiMoB/-Al_2O_3 catalyst by liquid-phase furfural hydrogenation

Amorphous MoNiB/ -Al 2 O 3 alloy catalysts were prepared by reducing NiCl 2 ·6H 2 O and (NH 4 ) 6 Mo 7 O 24 ·4H 2 O supported on -Al 2 O 3 with NaBH 4 as reducing agent. Using liquid-phase hydro-genation of furfural (FFR) as a probe reaction, the activity of MoNiB/ -Al 2 O 3 was examined. Compared to NiB and NiMoB, NiMoB/ -Al 2 O 3 exhibited excellent activity and selectivity towards furfuryl alcohol (FFA). After reaction for 3.0 h at 80 ℃ and 5.0 MPa in methanol, FFR conversion reached 99% with FFA yield o...     

Cu掺杂TiO_2作为SERS基底的研究

本文采用溶胶-水热法制备了TiO2及Cu掺杂的TiO2纳米粒子作为表面增强拉曼光谱(SERS)活性基底,观察到当4-巯基苯甲酸吸附在3%Cu掺杂的TiO2表面上时,其SERS信号得到了最大程度的增强.Cu离子掺杂进TiO2晶格时会使TiO2表面的缺陷浓度(表面态)得到增加,一定量的缺陷浓度对TiO2-to-Molecule的电荷转移机理起到促进作用,进一步证明了化学增强机理在SERS现象的贡献.     

Lennard-Jones团簇最低能量构型的预测

针对Lennard-Jones(LJ)团簇的结构优化问题,在前人工作的基础上,提出了一个新的无偏优化算法,即DLS-TPIO(dynamic lattice searching method with two-phase local searchand interior operation)算法.对LJ2-650,LJ660,LJ665-680这666个实例进行了优化计算.为其中每个实例所找到的构型其势能均达到了剑桥团簇数据库中公布的最好记录.对LJ533与LJ536这两个算例,所达到的势能则优于先前的最好记录.在DLS-TPIO算法中,采用了内部操作,两阶段局部搜索方法以及动态格点搜索方法.在优化的前一阶段,内部操作将若干能量较高的表面原子移入团簇的内部,从而降低团簇的能量,并使其构型逐渐地变为有序.与此同时,两阶段局部搜索方法指导搜索进入更有希望的构型区域.这种做法显著地提高了算法的成功率.在优化的后一阶段,借用动态格点搜索方法对团簇表面原子的位置作进一步优化,以再一次降低团簇的能量.另外,为识别二十面体构型的中心原子,本文给出了一个简单的新方法.相比于文献中一些著名的无偏优化算法,DLS-TPIO算法具...     

Th(Ⅳ)在凹凸棒石表面的吸附机理

采用连续电位滴定法研究了天然和高温活化凹凸棒石的表面酸碱和电荷分布性质,利用表面配位模型和FITEQL3.2程序探讨了Th(Ⅳ)在高温活化前后凹凸棒石上的吸附机理.结果表明天然凹凸棒石表面主要以离子交换位(≡XNa/K)、强吸附点位(≡SsOH)和弱吸附点位(≡SwOH)为主;而高温活化凹凸棒石表面则主要以强吸附点位(≡SsOH)和弱吸附点位(≡SwOH)为主.当pH<2.5,Th(Ⅳ)在水溶液中主要以Th4+存在;而当pH>3.0时,Th(Ⅳ)则主要以水解形态存在(例如Th(OH)22+,Th(OH)3+和Th(OH)40).Th(Ⅳ)在天然凹凸棒石表面上的吸附主要以离子交换作用(≡X2Th)和内层配合作用(≡SsOTh)为主,而在高温活化凹凸棒石表面上则主要形成内层配合物(≡SwOTh和≡SsOThOH).胡敏酸(HA)对Th(Ⅳ)在高温活化凹凸棒石上吸附有一定的促进作用,且使Th(Ⅳ)的吸附机理和种态发生明显的改变(主要以≡SsO-CO-HA-Th和≡SsOTh种态存在).Th(Ⅳ)在高温活化凹凸棒石上的吸附是不可逆过程,但当HA存在时,Th(Ⅳ)在高温活化凹凸棒石上会发生解吸.     

THREE POINT BOUNDARY VALUE PROBLEMS FOR NONLINEAR FRACTIONAL DIFFERENTIAL EQUATIONS

In this paper, we study existence and uniqueness of solutions to nonlinear three point boundary value problems for fractional differential equation of the type c D δ 0+ u(t) = f (t, u(t), c D σ 0+ u(t)), t ∈ [0, T ], u(0) = αu(η), u(T ) = βu(η), where 1 < δ < 2, 0 < σ < 1, α, β∈ R, η∈ (0, T ), αη(1 -β) + (1-α)(T βη) = 0 and c D δ 0+ , c D σ 0+ are the Caputo fractional derivatives. We use Schauder fixed point theorem and contraction mapping principle to obtain existence and uniqueness results. Examples are also included to show the applicability of our results.