Mujammel Haque

Influence of natural dye adsorption on the structural, morphological and optical properties of TiO2 based photoanode of dye-sensitized solar cell

Abstract Porous photoanodes of dye-sensitized solar cells (DSSCs) can adsorb specific type of natural or organic dyes. Adsorption of the dye results in a change of the structural, morphological and optical characteristics of the photoanode. In this work, we present a comparative study on the adsorption effect of natural dye (Curcuma Longa sp.) on the structural, morphological and optical properties of mesoporous titanium dioxide (TiO2) photoanode on indium tin oxide (ITO) coated glass. A number of investigations including XRD, UV-Vis spectroscopy, EDS, and SEM were carried out to observe the variations due to adsorbed dye on TiO2 surface. XRD characterization revealed the effect of dye adsorption on specific surface area (SSA), crystallite size, and morphological index (MI). In this case, increasing SSA with decreasing particle size was found for both dye adsorbed and dye free DSSC photoanode samples. Also, the MI and SSA were found to be directly and inversely proportional to the crystallite size respectively. UV-Vis-NIR spectroscopy showed that dye adsorption changes the light absorption, transmittance, and optical bandgap of the photoanode. Average atomic mass percentage of titanium (Ti) and oxygen (O) obtained from EDS analysis proved the presence of TiO2 in the mesoporous photoanode. In SEM images, significant morphological changes of mesoporous TiO2 surface appeared because of dye adsorption.

Efficacy and Safety of Thalidomide as Adjunct Therapy in Refractory Systemic Juvenile Idiopathic Arthritis Patients

About 50% of systemic onset juvenile idiopathic arthritis (sJIA) patients run a recalcitrant disease course and resistant to the conventional disease modifying anti inflammatoy drugs (DMARDs), ultimately resulting in permanent disability from joint destructions. Thalidomide has been reported as an effective and safe drug in the management of systemic JIA due to its immunomodulatory properties. This was an interventional study, aimed to evaluate the efficacy of thalidomide in refractory JIA patients. Twenty five systemic JIA patients who were refractory to conventional DMARDs were included in this study. These patients were prescribed thalidomide at a dose of 2-3mg/kg/day for 12 months. Efficacy of thalidomide was assessed by using Wallace criteria at 6th month and 12th month of thalidomide treatment. Active arthritis was improved in 55% and 73% of the patients at 6th and 12th month of thalidomide treatment respectively. Fever and rash subsided in 72.8% and 81.2% of patients respectively at 12th month of follow up. Hepatosplenomegaly and lymphadenopathy regressed in 100% of patients at 12th month follow up. ESR was also improved in 50% and 68.2% cases at 6th and 12th months respectively. Few minor side effects were observed like transient elevation of liver enzyme and somnolence in this study. It may be concluded that thalidomide is safe and effective in refractory JIA patients.

Drug Compliance in Children with Juvenile Idiopathic Arthritis and Reasons for Poor Compliance

Children with chronic disorders are at risk for a higher medication non-adherence. Juvenile idiopathic arthritis (JIA) is a chronic childhood disorder where often medication non-adherence is an issue. The purpose of this study was to assess drug compliance of JIA patients,to find out the proportion of patients having poor drug compliance and to find out possible reasons of poor drug compliance. This was a retrospective study conducted in the Pediatric Rheumatology follow up clinic, Department of Pediatrics, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. All JIA patients attending pediatric rheumatology follow up clinic during the study period was included. Data were collected using a structured questionnaire. Among the total 900 registered JIA cases, 116(12.9%) patients had poor compliance. Among 116 poor compliant patients, systemic onset JIA cases were the highest (34.5%), followed by enthesitis related arthritis (30.2%). Among the poor compliant patients, 6.9% patients had regular follow up and 93.1% had irregular follow up. Major reasons of poor compliance were financial crisis, lack of awareness and difficulty in transportation. Poor compliance to treatment of JIA in our setting was common. The most important reason for poor compliance was financial crisis.

Influence of Different Metals Back Surface Field on BSF Silicon Solar Cell Performance Deposited by Thermal Evaporation Method

This paper presents comparison of thermal evaporation method based passivation and BSF formation with different materials (Au, Al, and Cu). Silicon solar cells with different rear surface contact using these materials were fabricated. A comprehensive comparison of the samples have been carried out to find better back surface contact regarding the efficiency by investigating I-V characteristics, fill factor, external quantum efficiency and carrier diffusion length and lifetime, etc. Experimental data revealed that Cu based back surface contact has maximum output efficiency of about 13.73%, whereas Au shows maximum external quantum efficiency of about 86%. Moreover, use of Al shows the maximum carrier diffusion length 97.2μm and highest carrier lifetime of 3.5μs with overall cell efficiency of 12.90% indicating that Al is a promising material for back contact for n+-p-p+ back surface field silicon solar cell.