Sh. Ebrahim

CdTe quantum dots as a novel biosensor for Serratia marcescens and Lipopolysaccharide

The main objective of this work is to synthesize CdTe quantum dots (QDs) conjugated with Concanavalin A (Con A) as a novel biosensor to be selective and specific for the detection of Lipopolysaccharide (LPS). In addition, the conjugated CdTe QDs-Con A was used as fluorescence labels to capture Serratia marcescens bacteria through the recognition between CdTe QDs-Con A and LPS of S. marcescens. The appearance of the lattice plans in the high resolution transmission electron photograph indicated a high crystalline with an average size of 4-5 nm for the CdTe QDs. The results showed that the relative fluorescence intensity of CdTe QDs-Con A decreased linearly with LPS concentration in the range from 10 to 90 fg/mL and with correlation coefficient (R(2)) equal to 0.9713. LPS surrounding the S. marcescens bacteria was bound to the CdTe QDs-Con A and leads to quenching of PL intensity. It was found that a good linear relationship between the relative PL intensity and the logarithmic of cell population of S. marcescens in range from 1×10 to 1×10(6) CFU/mL at pH 7 with R(2) of 0.952 was established.

Effect of the functionalization process on the performance of SiGe MEM resonators used for bio-molecular sensing

Abstract Several SiGe Micro–Electro Mechanical (MEM) double clamped beam resonators with different lengths were chemically functionalized and electrically measured. The impact of each functionalization step, including oxidation, silanization, immobilization and blocking, on the resonators’ performance was studied. The resonance frequency of these resonators was measured before and after each processing step. The oxidation and blocking steps were found to have the greatest impact on the resonator’s performance. Fragility of long beam resonators is investigated.

A Novel Chloropyrifos Electrochemical Sensor Based on Polyaniline/Carbon Nanotubes Composite

Polyaniline nanofibers were prepared chemically in both emiraldine base (EB) and emiraldine salt (ES) forms. The composite of polyaniline emiraldine salt with single walled carbon nanotubes (SWCNTs) was developed. Electrochemical sensors based on polyaniline nanofibers and its composite have been developed for the detection of chloropyrifos. Chloropyrifos exhibits one well defined reduction peak. The maximum peak current was linearly related to chloropyrifos concentration in the range from 0.2 μM to 1.4 μM. It was found that the SWCNTs improved the sensitivity of the polyaniline base graphite electrode from 3.0 mA/μM for polyaniline base to 9.69 mA/μM for ES-SWCNTs composite electrode.

Fabrication of Infrared Detector Based on of Polyaniline/Polyvinylidene Fluoride Blend Films and their Pyroelectric Measurement

Infrared detection based on polymeric materials is continuously developed in order to be cheap and easy to processing and also having high pyroelectric coefficient to convert heat to electrical signal. PANI/DBSA was blended with polyvinylidene fluoride (PVDF) with different weight ratios to improve pyroelectric coefficient and electrical conductivity of PVDF. The temperature dependence of the electrical conductivity is measured in the range of 20-100 °C It was found that the pyroelectric coefficient increased from 1.5×10-8 C/m2 °C for pristine PVDF to 2.61×10-5 C/m2 °C at 25 wt.% PANI at 30 °C. The infrared detector circuit connected to the gate of a voltage follower JFET with high input impedance was designed to convert the high output impedance of the sensor into the output resistance. The output from the sensor and JFET is amplified in two stages of operational amplifier with high voltage gain with low noise.

Characterization and Testing of the Locally Fabricated Encapsulants in Egypt for Commercial Photovoltaic Modules Production

In this work, different locally fabricated adhesive materials were examined to be used as an encapsulant for producing of photovoltaic modules. All the selected samples were characterized by FT-IR spectroscopy, TG instrument, UV-VIS spectrophotometer and electrical resistance meter. In addition, all the samples under investigation were examined by aging tests according to IEC standards for testing their stability and durability. The polymethacrylate material with UV stabilizer can be considered as an excellent commercial candidate for photovoltaic module encapsulant due to its high optical transmission, good adhesive strength with the glass, high photo-stability, high thermal stability and high electrical insulation (electrical resistance).