Bombieri's Theorem in Short Intervals

Under the assumption of sixth power large sieve mean-value of Dirichlet L-function,we improve Bombieri's theorem in short intervals by virtue of the large sieve method and Heath-Brown's identity.     

Indirect Differential Pulse Voltammetric Determination of Aluminum Biological Samples in the Presence of 3, 4-Dihydroxyphenylalanine

ABSTRACT

Indirect differential pulse voltammetric (DPV) determination of aluminum in the presence of 3, 4-dihydroxyphenylalanine (L-dopa) with glass carbon electrode as working electrode has been described. The method relies on the decrease of DPV anodic peak current of L-dopa with the addition of Al^III The decreasing value of the peak current is linear with the increase of Al^III concentration. Under the optimum experimental conditions (pH 4.8, 6×10^?4 M L-dopa, 0.06M NaAc - HAc ¹buffer solution), the linear ranges are 4.0×10^?7 - 5.2×10^?6 M and 7.2×10^?6 - 4.5×10^?5 M. The relative standard deviation for 8×10^?6 M aluminum is 1.0% (n = 8) and the detection limit is 3.5×10^?7 M. A number of foreign species for interference have been studied. The method has been applied to determine aluminum in drinking water, synthetic renal dialysate and urine samples.     

Contribution à l'étude Électrochimique de Dérivés de l'Acide Mercapto-2 Pyridinecarboxylique-5. II

Abstract

Electrochemical caracteristics of 2-mercaptopyridine-5-carboxylic acid and its methylic ester have been determined using recent polarographic techniques. Measurements have been carried out as a function of parameters such as frequency, others surimposed signals and as a function of concentration and pH. Results are compared to those obtained for selectively methylated on sulfur or nitrogen atoms derivatives. Interpretations of the data are given. The optimal conditions for a quantitative determination by D.C. and differential pulse polarography are fixed.     

Reflecting a single attosecond pulse by using periodic Mo/Si multilayer mirrors with different layers

The reflecting of a single attosecond pulse from a periodic Mo/Si multilayer was investigated. By changing the number of bi-layers, the periodic multilayer showed greatly different spectral and temporal responses of the attosecond pulse reflection, which has been discussed in detail in this paper. The capability of attosecond pulse reflection of the periodic multilayers with different bi-layer numbers has been evaluated using suitable temporal parameters. In addition, the condition for obtaining high-efficiency reflected pulses has been analyzed by comparing the pulse responses of the periodic multilayer with different layers. The transfer-matrix method together with the fast Fourier transform has been used in our simulation.     

Investigation of entrance effects on particle electrophoretic behavior near a nanopore for resistive pulse sensing

Resistive pulse sensing using solid-state nanopores provides a unique platform for detecting the structure and concentration of molecules of different types of analytes in an electrolyte solution. The capture of an entity into a nanopore is subject not only to the electrostatic force but also the effect of electroosmotic flow originating from the charged nanopore surface. In this study, we theoretically analyze spherical particle electrophoretic behavior near the entrance of a charged nanopore. By investigating the effects of pore size, particle–pore distance, and salt concentration on particle velocity, we summarize dominant mechanisms governing particle behavior for a range of conditions. In the literature, the Helmholtz–Smoluchowski equation is often adopted to evaluate particle translocation by considering the zeta potential difference between the particle and nanopore surfaces. We point out that, due to the difference of the electric field inside and outside the nanopore and the influence from the existence of the particle itself, the zeta potential of the particle, however, needs to be at least 30% higher than that of the nanopore to allow the particle to enter into the nanopore when its velocity is close to zero. Accordingly, we summarize the effective salt concentrations that enable successful particle capture and detection for different pore sizes, offering direct guidance for nanopore applications.     

A Novel Approach to All-Optical Generation of Ultra-Wideband Signals

Abstract

The generation of ultra-wideband signals in the optical domain is highly desirable for ultra-wideband-over-fiber systems, which has recently become a topic of interest. In this article, a novel and simple approach to achieve all-optical generation of ultra-wideband signals is proposed, which is based on delaying and superimposing optical Gaussian pulses with opposite polarities. The proposed system is capable of generating both ultra-wideband monocycle and doublet pulses, and the polarity of the generated ultra-wideband monocycle pulses can be fast-switched to implement pulse polarity modulation with the required bit pattern. A model to describe the proposed system is developed, and the generation of ultra-wideband signals is demonstrated with simulations and a proof-of-concept experiment.     

罐装橙汁超高温瞬时灭菌的数值模拟研究

由于对橙汁的灭菌工艺没有进行精确的研究,在橙汁的实际生产中经常是使用过度灭菌来保证果汁灭菌的彻底。过度灭菌不但引起橙汁生产的能耗增加而且会导致橙汁的营养成分的损失。本文分析了果汁中常见的细菌,得出了灭菌结束时所需的最低温度;在此基础上利用数值模拟的方法对橙汁的超高温瞬时灭菌进行了计算。同时使用实验对CFD计算的结果进行了验证,误差在9.5%以内,表明CFD对橙汁的超高温灭菌的模拟是可行的。模拟得出了不同温度时的灭菌的最理想时间条件分别为:135℃(408 K),13 s;140℃(413K),12 s;145℃(418 K),12 s;150℃(423K),11 s。     

Determination of Codeine,Dionin and Thebaine by Differential Pulse Polarography

Abstract

The method proposed for determining codeine, dionin and thebaine by differential pulse polarography is based on the reduction (in ammoniacal medium) of the nitroderivatives obtained by dissolving the substances in concentrated nitric acid. The values of the reduction potentials range between -0.45 and -0.69 V. Morphine and heroine do not interfere in the determination of the mentioned alkaloids.     

Movement and amplification of exciton condensed phase pulses and interaction between pulses in semiconductor quantum wells

Formation and movement of an exciton pulse in an inhomogeneous potential are studied. It is shown that the pulse does not blur and the maximum of the exciton density in the pulse remains constant during the exciton lifetime if the pulse is formed from the condensed phase. The path, traversed by the excitons, can be increased by imposing an additional laser pulse on the system. Thereby, such a system can be used for information transmission over the exciton condensed phase.     

Harmonic and attosecond pulse enhancement in the presence of noise

<正>In this paper,we theoretically investigate the effect of noise on the photoionization,the generation of the high-order harmonic and the attosecond pulse irradiated from a model He~+ ion.It shows that by properly adding noise fields,such as Gaussian white noise,random light or colored noise,both the ionization probabilities(IPs) and the harmonic yields can be enhanced by several orders of magnitude.Further,by tuning the noise intensity,a stochastic resonance-like curve is observed,showing the existence of an optimal noise in the ionization enhancement process.Finally,by superposing a properly selected harmonic,an intense attosecond pulse with a duration of 67 as is directly generated.