Sharif Digital Repository

The first report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb(II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent, the color and UV–vis spectra of AuNPs are changed indicating the aggregation of AuNPs. Addition of the aggregation reagents which are firstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is different because of distinct stability... 

Multisensor arrays employing various sensing principles are a rapidly developing field of research as they allow simple and inexpensive quantification of various parameters in complex samples. Quantitative analysis with such systems is based on multivariate regression techniques, and deriving of traditional analytical figures of merit (e.g., sensitivity, selectivity, limit of detection, and limit of quantitation) for such systems is not obvious and straightforward. Nevertheless, it is absolutely needed for further development of the multisensor research field and for introducing these instruments into the general context of analytical chemistry. Here, we report on the protocol for... 

Development of simple and rapid methods for identification of pesticides, due to their broad usage and harmful effects on mammals, has been known as a critical demand. Herein, we have introduced a silver nanoparticle (AgNP)based colorimetric sensor array for simultaneous identification of Azinphosmethyl (AM)and Phosalone (PS)pesticides. In the presence of the target pesticides, unmodified AgNPs at various pHs (4.5, 5.5 and 9.5)showed different aggregation behaviors. As a result of aggregation, the color and UV–Vis spectra of AgNPs changed differentially, leading to distinct response patterns for AM and PS. The aggregation induced spectral changes of AgNPs, were used to identify AM and PS... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

Nanoparticles (NPs) are increasingly being used in different branches of science and in industrial applications; however, their rapid detection and characterization at low concentration levels have remained a challenge; more specifically, there is no single technique that can characterize the physicochemical properties of NPs (e.g. composition and size). In this work we have developed a colorimetric sensor array for defining the physicochemical properties of NPs in aqueous solution with ultra-low concentrations (e.g. 10-7g ml-1 for gold NPs). Various NPs were readily identified using a standard chemometric approach (i.e. hierarchical clustering analysis), with no misclassifications over 400... 

This paper proposes a new medium-access control (MAC) protocol designed for wireless sensor networks. A wireless sensor network is an array of large number of sensors interconnected by a multi-hop ad-hoc network. The primary objective for the sensor network is achieving to low-power consumption while latency is usually less important compare to traditional wireless networks. This characteristic of sensor network motivates the design of new MAC layer so that power consumption is reduced. In this paper, a novel traffic-aware algorithm based on distributed node schedule management (DMD) protocol is introduced that utilizes distributed dynamic node scheduling strategy to dramatically increase... 

In smart antenna systems, The localization and direction of desired source(s) must be known. In this paper, we introduce a method called "DMSAE" (Direction finding of Multiple Sources by Alternating Eliminations) to find the radio directions of signals impinging on an arbitrary antenna array and the number of the signals. This method which is based on the Minimum Variance Distortionless Response (MVDR) algorithm, can not only detect the direction and the number of sources, simultaneously, but also has better resolution ability compared to the other conventional direction finding algorithms. This method can also detect very weak sources when other powerful sources exist in the environment. In... 

A new reflectance optical sensor array for locating fetal signal transabdominally has been determined in this study. The selection of optical sensor array is based on the highest Irradiance (μW/m2) value estimated on respected detectors. A three-layer semi-infinite tissue model which consists of maternal, amniotic fluid sac and fetal tissues is employed to study the optical sensor array configuration. By using statistical error approach, the number of rays injected to the system can be set to 1 million rays with ±3.2% of simulation error. The simulation results obtained from Monte Carlo technique reveal that diamond configuration is the most suitable configuration of reflectance optical... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

In this study, for rapid identification and discrimination of catecholamine neurotransmitters in the presence of ascorbic acid (AA), a tricolor fluorescence probe has been constructed by integrating three recognition elements including blue carbon dots (bCDs), green CdTe quantum dots (gQDs) and red CdTe quantum dots (rQDs) into a single well. The proposed array exhibited ternary fluorescence emissions at 450, 520 and 630 nm with an overall luminescent pink emission under a single wavelength excitation (365 nm). In order to produce distinct response patterns from a single fluorimetric test, the spectral changes and the corresponding color variations of the multichannel fluorescence probe were... 

Detection of nitroaromatic explosives is of strong concern because of human health, public safety, environment, and military issues. In this study, we present a ratiometric sensor array for detection and discrimination of widely-used nitroaromatics (i.e., 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), and 2,4-dinitrotoluene (DNT)). In the design of sensor elements (SE) we employ blue emissive carbon dots (BCDs) in combination with yellow (SE-A) and red (SE-B) emissive cadmium telluride quantum dots (CdTe QDs). The fluorescence intensity of BCDs, YQDs, and RQDs is quenched by TNT, DNT, and TNP in various degrees. Both TNT and TNP cause the quenching and spectral shift of BCDs (TNT... 

Development of a convenient and inexpensive method for identification and detection of nanoparticles (NPs) is of great interest. In this work, we have developed a novel and simple chemiluminescence based sensor array, with its sensing mechanism mimicking that of olfactory and gustatory systems for discriminating a set of NPs. The proposed method is based on the enhancement effect of NPs on luminol–oxidant CL intensity by their catalytic effect. Three kinds of oxidant including H2O2, AgNO3, and K3Fe(CN)6 were used as sensor elements and NPs exhibited diverse enhancing responses to different oxidant-luminol CL systems producing unique response patterns that were identified through heat map and...