In the present study, a new biosensor for 5-Fluorouracil was described using modified goldelectrode and Fast Fourier transform square wave voltammetry (FFT SWV). Calf thymus DNAimmobilization was on a gold electrode decorated with polyaniline and gold nanoparticles. Theelectrochemical characteristics of the electrodes were investigated by cyclic voltammetry, andelectrochemical impedance spectroscopy. After interaction DNA with the analyte, a dramaticdecline in [Fe(CN)6]/[Fe(CN)6]]3-/4- signal was observed which could be used as the signal. Theimportant parameters of the detection system, such as, pH were optimized. The linear dynamicrange of the biosensor was1×10-9 to 1×10-6 M (r2=0.996) limits of detection of2.5×10−10 M. In addition to the wide linear range response, the proposed method demonstratedacceptable sensitivity, repeatability and long-term stability. Future experiments could be performedto examine several other effective factors so as to decrease the influence of the environment andinvestigate its application to FFTSWV detection. پرونده مقاله

The invisible inks have many applications, including the use of banknote printing, code load, securitydocuments and much of its application in the exchange of security information. Photoluminescenceproperties of lanthanide compounds that attracted the attention of many scholars in recent decades are one ofthe important factors in drying and fluidity of the ink. The solvent evaporation rate has a special importancein the formulation of resin systems. The solvent evaporation rate is often expressed in compare with astandard solvent evaporation rate, such as normal butylated acetate or ethyl ether. The mixing of somesolvents may be used due to the formation of an azeotrope and the more rate of evaporation. In theformulation of the inks, the use of the weight ratio compared with the volume relationship has thisadvantage, which requires less mathematical calculations and operations, especially that this score is usefulduring the early stages of formulation. In this research, from 160 materials that were used, 11 items played afundamental role, which were selected based on their formulation planned. The purpose of this research wasto produce invisible ink.For this purpose, the relevant complexes were prepared, designed and thecomposition of the percentage of invisible ink was optimized. Eventually, obtainedresults were evaluated. پرونده مقاله