Sharif Digital Repository

At the first part of this thesis, a pyrolitic graphite electrode (PGE) modified with graphite/nanodiamond film (GND) was applied as a sensitive electrochemical sensor for determination and study of electrochemical behavior of tryptophan (Trp) and 5-hydroxytryptophan (5-HTP) in aqueous solutions. The results showed that GND caused a remarkable increase in the peak currents so the GND/PGE electrode surface was more sensitive to the concentration of Trp and 5-HTP than the PGE surface. The determination of Trp and 5-HTP were investigated by stripping voltammetry. Experimental parameters such as scan rate, pH, accumulation conditions and amount of the modifier used on the PGE surface were... 

Part 1: A novel modified pyrolytic graphite electrode with nanodiamond/graphite was fabricated. The electrochemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) are studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique.The prepared electrode shows an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence... 

In this study, the aging of the LiFePO4/graphite cell was investigated in two different types of 18650 Li-ion batteries during cycling at various C-rates (0.5, 1, 2, 3, 4C) and high temperature under long-term cycling. An amount of 20% Capacity loss was considered as the end of the cycling. Batteries with a capacity of 1500 mAh after this capacity drop, experience 60, 120, 1502, and 2155 cycles, at the rates of 4, 3, 2, and 1C , and batteries with capacity of 1400 mAh was also 60, 360, 1100, 1000, and 805 cycles at a rate of 0.5C. Capacity decrease of the cell is in linear relationship with cycle number and the slope of the capacity-fading line increases with elevating current rate. Aging... 

One of the remarkable subject in advanced electrochemistry is, design and architecting new advanced materials with new electrochemical capabilities. One of the notable capabilities is electrocatalysis. Extensive researches are carrying out into the design and preparation of electrocatalyst materials to take advantage of these materials in fabrication of electrochemical sensors and storage/conversion devices. In this field nonoporous materials attracted a lot of attentions due to their unique features. In order to make use of the nanoporous materials as the electrocatalysts, these materials must be fabricated into continuous supported thin films on the electrode surface, which is the... 

At the first part of this thesis, a pyrolitic graphite electrode (PGE) modified with new coccine/multi-walled carbon nanotubes film (NC/MWCNT) was applied as a sensitive electrochemical sensor for determination and study of electrochemical behavior of tyrosine (Tyr) in aqueous solutions. The results showed that NC/MWCNT caused a remarkable increase in the peak current so the NC/MWCNT/PGE electrode surface was far more sensitive to the concentration of Tyr than the PGE surface. The determination of Tyr was investigated by linear sweep voltammetry (LSV). Experimental parameters, such as scan rate, pH and amount of the modifier used on the PGE surface were optimized by monitoring the LSV... 

Today, despite the notable progress in diagnostics and therapeutics, cancer remains the second cause of death worldwide. This rather high mortality rate is often attributed to cancers diagnosed at late stages, including prostate cancer. Among the techniques approved for prostate cancer diagnosis, total or free prostate-specific antigen screening using blood serum samples is the sole method able to detect prostate cancer at an early stage. This test has led to a significant decrease in prostate cancer-related deaths. Nonetheless, it possesses several drawbacks, such as the complex, costly, and time-consuming conventional methods utilized in clinical laboratories to assess the concentration of... 

In the first part, preparation of different kinds of polypyrrole/carbon composites and their application for drug analysis are described. In the first work, A very sensitive electrochemical sensor constructed from a glassy carbon electrode modified with a layer-by-layer MWCNT/doped overoxidized polypyrrole (oppy/MWCNT /GCE) was used for the determination of acetaminophen (AC) in the presence of codeine and ascorbic acid (AA). In comparison to the bare glassy carbon electrode, a considerable shift in the peak potential together with an increase in the peak current was observed for AC on the surface of oppy/MWCNT/GCE, which can be related to the enlarged microscopic surface area of the...