HETEROCYCLIC SYNTHESIS USING NITRILIMINES: PART 8†. SYNTHESIS OF AROMATIC 1,2,4-TRIAZOLES

A series of new 1,2,4-triazole derivatives (6a-p) have been synthesized by the reaction of amidines 3 with certain nitrilimines 2. The structures of newly synthesized compounds are confirmed by their analytical and spectral data including IR and NMR. Key words: 1,2,4-triazoles, amidines, nitrilimines, cycloadditio

Incorporating Thiobarbituric Acid with 1,2,4-Triazin-6-one Containing Nitroarginine Moiety

Abstract : Nitrilimines (2a,b), react with nitroarginine methyl ester (3) at room temperature, through cyclocondensation reaction, to give 1-aryl-3-substituted-1,2,4-triazin-6-ones (4a,b). Condensation of these compounds with thiosemicarbazide give the thiosemicarbazone derivatives (5a,b ) which upon heterocyclization with malonic acid give the thiobarbituric acid derivatives (6a,b). The structures of these compounds were deduced from: IR, mass, 1H and 13C NMR spectra. Keywords Nitrilimine , nitroarginine methyl ester, 1,2,4-triazin-6-ones, thiosemicarbazone, thiobarbituric acid derivatives

Design and characterization of homogeneous TM nonlinear waveguide sensors

This work is devoted to a three-layer sensor bounded on one side by a nonlinear clad of intensity dependent retractile index. Sensitivity of this configuration is theoretically discussed and the exact condition to maximize this sensitivity is also determined. Behavior of sensing sensitivity is accounted for through power flow and cut-off considerations. Finally, we establish a method of determining e proper dimensioning of the sensor to execute its maximum sensitivity. We believe these concepts may be demonstrated and carried out for future novel sensors

Design of nonlinear optical waveguide sensors with metallic cores by uniform field profile approach

TE waves can propagate in metal film of three waveguide structure if at least one of the covering media is nonlinear. The waveguide sensor under consideration consists of a metal wave guiding film coated with two nonlinear claddings. Contrary to what has been recently predicted, it is shown here that uniform field profile may be achieved under the suitable choice of the dielectric constants of the surroundings. Electric fields and fraction of power flow down the sensor layers are studied here. We expect this kind of planar waveguide sensors may be realized experimentally and will have applications in future opto-electronic devices. Uniform field approach has been discussed and implemented for the first time in investigating the waveguide sensors

Design of nonlinear surface wave guided sensors

In recent years, optical wave guided sensors have attracted scientists for the development of biochemical and biomedical optical sensors in addition to optical communicative devices. These sensors show immunity to electromagnetic fields and have no danger of ignition so that they are used in cases of risky environments. Optical sensors have additional advantages: higher sensitivity, higher stability and lower price. Surface sensing, in particular, is used in recognition of adsorption or deposition on a certain surface such as the detection of adsorbed proteins, antibodies and bacteria cells. In this work, a sensing layer (extra ultra-thin film) iss assumed to rest on surface of a thin film covered with a nonlinear clad of lief dependent refractive index. A normalized analysis for the design of evanescent wave sensors is carried out for linear waveguide sensors with normal asymmetry (i.e., substrate refractive index is higher

Design and Analysis of Nonlinear Optical Waveguide Sensors

Recent years have shown increased interest in the investigation of integrated optical sensors [1-4] due to their miniature, high sensitivity, small size, immunity to electromagnetic interference and low price. Biochemical and biomedical sensors are examples of using planar integrated optical wave guide in their structures in both homogenous and surface sensing. In the past few years, there was [5-7] a significant amount of work regarding the applications of lasers and nonlinear optical materials in a large number of opto-electronics devices. The changes of the refractive index in nonlinear media may be used to control the sensitivity of nonlinear wave guide sensors. Abadla, Shabat, and D. Jäger [8, 9] have shifted the study of linear wave guide sensors to nonlinear wave guides sensors. This paper presents our recent works on nonlinear wave guide sensors. Novel nonlinear wave guide sensors are designed for the first time. We derive an extensive theoretical analysis of nonlinear wave guide structure sensors and the conditions for the maximum achievable sensitivity. In homogeneous sensing, the wave guide sensor structure consists of a dielectric film sandwiched between a linear substrate and a nonlinear cladding. An extra very thin layer is added above the film in surface sensing. In both cases, the nonlinear cladding is considered to have an intensity dependent refractive index. Computer programs based on the derived mathematical modeling are developed to analyze the propagation characteristics of various integrated optical nonlinear wave guide structures. The theoretical requirements for reaching high sensitivity of the proposed nonlinear

Characterization of homogenous TM nonlinear waveguide sensors

This work is devoted on a three-layer sensor bounded from one side by a nonlinear clad of intensity dependent refractive index. A normalized analysis of sensitivity of this configuration and the condition to maximize this sensitivity is introduced. Behavior of sensing sensitivity is accounted for through power flow and cut-off considerations. We establish a method of determining the proper dimensioning of the sensor to execute its maximum sensitivity. We found that the sensitivity is higher in nonlinear sensors than in linear case in spite of appearing at lower wave guiding widths so that nonlinear sensors are advisable in accurate sensing

Simulation of sensing characteristics in optical nonlinear waveguide sensors

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Excitation of TE surface polaritons on metal–NIM interfaces

In this work, we consider different waveguide structures comprising a metal and a dispersive negative index material (NIM) which has negative permittivity and permeability over a frequency band in the microwave range of several GHz. In the first structure, one interface separating a semi-infinite metal and a semi-infinite NIM is assumed. In the second structure, a NIM slab is sandwiched between a metal and a dielectric material whereas in the third structure a metal slab is embedded in a NIM medium. The dispersion relations and the conditions for surface polariton excitation at the interfaces are derived, plotted and discussed. Penetration depth and modal refractive index are also studied

خواص الموجهات الموجية المسطحة متعددة الطبقات المحتوية على مواد يسارية

We examine analytically the propagation of TE-polarized waves in a four-layer slab waveguide structure. One of the layers is considered as a Left-handed or metamaterial with simultaneously negative and . The dispersion relation of such a structure is shown in terms of the normalized thickness and the asymmetry factors. The effect of the doubly negative material parameters on the propagation characteristics has been examined. The variation of the effective index of the structure with different parameters of the layers is studied extensively. A comparison of the structure under consideration with the conventional right handed four-layer waveguide structure is also shown.يدرس البحث انتشار الموجات المستقطبة عمودياً في الموجهات الموجية المسطحة المكونة من أربع طبقات، إحدى هذه الطبقات مادة يسارية لها معامل سماحية ومعامل نفاذية سالبين، تم اشتقاق معادلة التشتت لهذه الموجهات ودراسة تأثير هذه المعاملات السالبة على انتشار الموجات، وكذلك تم دراسة تغير معامل الانكسار الفعال للتركيب المقترح مع المعاملات المختلفة مثل سمك الطبقة اليسارية وسمك الطبقة الموجهة، واهتم البحث كذلك بعقد المقارنات مع الموجهات الموجية المسطحة المألوفة المكونة من أربع طبقات