Browsing by Author "Islam, Faridul"

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Antimicrobial Activity of Cu(II) and Fe(III) with Pyridine Complexes as Ligands Contrary to Clinical Strains of Bacteria and Fungi Species
(Asian Journal of Chemistry, 2019) Islam, Faridul; Foisal, Jannat Al; Rahman, Mahbubur; Islam, Md Zahidul; Mimi, Mst. Afsana; Habib, Rasel; Hossain, Md. Amran; Chowdhury, Likson; Bhattacharjee, Sreebash Chandra; Cu, Daxiang
In this study, green coloured Cu(II) and red coloured Fe(III) complexes of pyridine were prepared and the elemental characterization confirmed their composition. The pyridine complexes of Cu(II) and Fe(III) were found very interesting and attractive as potential candidates with antimicrobial activity. Along with this, melting point, molar conductivity measurement, magnetic moment determination, electronic and FTIR spectroscopy were also measured to characterize the prepared complexes. Pyridine acts as monodentate which resulted in formation of square planar and octahedral structure of Cu(II) and Fe(III) complexes, respectively with the nitrogen atom pyridine ring by coordination bond. For antimicrobial activity studies Alternaria alternata, Bacillus cerelus, Botrgodiplodia theobromal, Colletotrichums corcolei, Escherichia coli, Fusarium equiseti, Macrophomina phaseolina, Salmonell typhi and Shigella dysenteriae were used. The prepared complexes showed inhibition against mycelial growth. Although the complexes showed satisfactory inhibition against the tested bacteria and fungi species, both of the complexes were comparatively better against bacteria than fungi compared to ligand.
Extraction, Radical Scavenging and Antimicrobial Activity of Essential Oils of Root of Dryopteris Marginalis
(Asian Journal of Chemistry, 2019) Islam, Md. Zahidul; Foisal, Jannat Al; Rahman, Mahbubur; Mimi, Mst. Afsana; Islam, Faridul; Habib, Rasel; Khan, Nowshin Farzana; Rahman, Md. Atiqur; Parvin, Tanzima; Cui, Daxiang
The aim of the study was to characterize the chemical constituents and determine antibacterial and antioxidant activities of essential oils and three different extracts of Dryopteris marginalis. The root had essential oil yield of 0.36 % (w/w) in which 12 organic compounds representing 97.22% of the root oils were identified. Tyranton was found as the most abundant component with 77.571 % of the total concentration in the essential oil. The zones of inhibition of different organic extracts against the tested bacteria were found in the range of 6.5-15 mm. Pseudomonas was the most vulnerable with MICs of 15.62 μg/mL by both ethyl acetate and petroleum ether extract producing 3.8 mm zone of inhibition. The essential oils extracted from roots of Dryopteris marginalis showed maximum 85.29 % inhibition of radical scavenging at 2 mg/mL concentration. Among all root extracts, methanol extract exhibited 41.11 % inhibition at 2 mg/mL concentration.
Kinetics of Oxygen Reduction Reaction of Polymer-Coated MWCNT-Supported Pt-Based Electrocatalysts for High-Temperature PEM Fuel Cell
(MDPI Publications, 2023-02-03) Haque, Md Ahsanul; Rahman, Md Mahbubur; Islam, Faridul; Sulong, Abu Bakar; Shyuan, Loh Kee; Rosli, Ros emilia; Chakraborty, Ashok Kumar; Haider, Julfikar
Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were obtained at −0.96 mAcm2. However, the ring current densities increased steadily from potential 0.6 V to 0.0 V due to their encounter with the hydrogen peroxide species generated by the oxygen reduction reactions. The kinetic limiting current densities (JK) increased gradually with the applied potential from 1.0 V to 0.0 V. It recommends that the ORR consists of a single step that refers to the first-order reaction. In addition, modified MWCNT-supported Pt electrocatalysts exhibited high electrochemically active surface areas (ECSA) at 24.31 m2/g of MWCNT-PBI-Pt, 22.48 m2/g of MWCNT-Nafion-Pt, and 20.85 m2/g of MWCNT-PTFE-Pt, compared to pristine MWCNT-Pt (17.66 m2/g). Therefore, it can be concluded that the additional ionomer phase conducting the ionic species to oxygen reduction in the catalyst layer could be favorable for the ORR reaction.
Simulation & Control Of SPWM Based Three Phase Voltage Source Inverter For Solar System
(Daffodil International University, 2018-11-01) Hossain, Md. Afjal; Islam, Faridul
Inverters are used in a large number of power electronics. Inverter is an alternative energy system that converts direct current (DC) into the alternating current (AC) and sometimes used as emergency backup of household electrical appliances and many others in the absence of alternating current (AC). Utility companies and generators produce sine wave alternating current (AC) power, which is used by most commonly available appliances today. This sine wave is not pure; it will be distorted when it passes through electronic device. To remove this unwanted frequency component from the signal filter is used so that we can get pure sine wave. Then this inverter can be controlled by using SPWM to operate a greater efficiency.