Improving the Sensitivity of a Quartz Crystal Microbalance for Biosensing by Using Porous Gold

 A quartz crystal microbalance can be used as a biosensor if biological receptor molecules (ligands) are attached to the crystal. To improve the sensitivity, the surface area of the gold electrodes on the crystal was increased by rendering the electrodes porous. This increased the response up to a factor of 3. A protein model system with human anti-myoglobin as ligand and sheep skeletal myoglobin at different concentrations as analyte was used. The quartz crystal was mounted in a flow-cell, where immobilisation, binding and regeneration of the surface were carried out. The kinetics of the model system was monitored under various experimental conditions. Received February 2, 2000. Revision June 30, 2000.     

An Unusual S-and N-Alkylation of Mercapto Substituted Heterocycles With O,O-Dialkyl Chlorophosphate/Thiophosphate

The reaction of different mercapto substituted heterocycles with o,o-dialkyl chlorphosphate or thiophosphates, gave the corresponding S- and N- alkylated derivatives instead of the expected phosphorylated products.     

A new spot test for nitro compounds

A simple, rapid, and highly sensitive method for the detection of micro amounts of nitro compounds has been developed. Nitro compounds are reduced into corresponding hydroxylamines with zinc dust and acetic acid and coupled with diazonium chloride to give hydroxytriazines which give an intense pink to violet color with diphenylamine in acetic acid medium. Quantities of 0.1 μg or less of nitro compounds can be detected in 0.25 ml of total solution by this method. The method is free from the common interference.     

黏性流体与热弹性微极蜂窝结构介质界面上受倾斜荷载作用时的弹性动力分析

研究倾斜荷载作用在黏性流体与热弹性微极蜂窝结构固体界面上时,荷载倾斜角的影响.假设倾斜荷载是法向荷载和切向荷载的线性组合.为求解该问题,对时间变量进行Laplace变换,对空间变量进行Fourier变换.通过引入势函数,获得了变换域中应力、温度分布和压力的表达式.利用数值逆变换技术,求得问题的物理解.同时,得到了频域中的表达式,以及变量适当变化时稳态情况下的表达式.用图形显示不同荷载源和荷载倾角变化时的响应.并且讨论了一些特殊情况.     

微极各向同性弹性板中的Rayleigh-Lamb波

研究了无应力作用条件下，均匀、各向同性、圆柱形微极结构弹性板中波的传播．导出了对称和斜对称模式下波传播的特征方程．对短波这一极端情况，无应力圆板中对称和斜对称模态波的特征方程退化为Pmyle曲表面波频率方程．并得到薄板的计算结果．给出了位移和微转动分量，并绘制了相应图形．给出了若干特殊情况的研究结果及对称和斜对称模态特征方程的图示．     

Numerical iterative method for Volterra equations of the convolution type

The objective of this paper is to present an algorithm from which a rapidly convergent solution is obtained for Volterra integral equations of Hammerstein type. Such equations are often encountered when describing the response of viscoelastic materials where the time dependency of the material properties is often expressed in the form of a convolution integral. Frequently, singularity is encountered and often ignored when dealing with the constitutive equations of viscoelastic materials. In this paper, the singularity is incorporated in the solution and the iterative scheme used to solve the equation converges within six iterations to a typical toleration error of 10^?5. The algorithm is applied to the strain response of a polymer under impulsive (constant) loading and the results show excellent correlation between the experimental and analytical solution. Copyright © 2010 John Wiley & Sons, Ltd.     

Squeezing and sub-Poissonian effects up-to fourth order in fifth harmonic generation

The concept of squeezing of the electromagnetic field is investigated in fundamental mode in fifth harmonic generation with the approximation |gt|²?1, where g is coupling constant and t, the interaction time between waves during the process. It has been found that squeezing occurs in amplitude, amplitude-squared, amplitude-cubed and fourth-order amplitude states of the field for selective phase values of field amplitude of fundamental mode. The dependence of squeezing on the photon number has also been investigated and found to be sub-Poissonian in nature. The signal to noise ratio has been studied in different order. It is found that the signal to noise ratio is higher in lower order.     

Nondifferentiable multiobjective Mond–Weir type second-order symmetric duality over cones

In this paper, a pair of Mond–Weir type nondifferentiable multiobjective second-order symmetric dual programs over arbitrary cones is formulated. Weak, strong and converse duality theorems are established under second-order K–F-convexity/K–η-bonvexity assumptions. A self duality theorem is also obtained by assuming the functions involved to be skew-symmetric.     

A Construction of Almost Steiner Systems

Let n, k, and t be integers satisfying . A Steiner system with parameters t, k, and n is a k‐uniform hypergraph on n vertices in which every set of t distinct vertices is contained in exactly one edge. An outstanding problem in Design Theory is to determine whether a nontrivial Steiner system exists for . In this note we prove that for every and sufficiently large n, there exists an almost Steiner system with parameters t, k, and n; that is, there exists a k‐uniform hypergraph on n vertices such that every set of t distinct vertices is covered by either one or two edges.     

Positive values of non-homogeneous indefinite quadratic forms of type (1, 4)

Let Г_r,n—r denote the infimum of all number Г > 0 such that for any real indefinite quadratic form inn variables of type (r, n—r), determinantD ≠ 0 and real numbers c₁; c₂,…, c_n, there exist integersx ₁,x₂,…,x_n satisfying 0 < Q(x₁+c₁,x₂ + c₂,…,x_n + c_n) ≤(Г|Z > |)^1/n. All the values of Г_r,n—r are known except for г_1,4. Earlier it was shown that 8 ≤Г_1,4 ≤16. Here we improve the upper bound to get Г_1,4 < 12.