Optical Properties of Solar Cells Based on Zinc(hydr)oxide and its Composite with Graphite oxide Sensitized by Quantum Dots

This thesis research focuses on developing a hybrid form of solar cell based on zinc(hydr)oxide and its composites with graphite oxide, TiO2, quantum dot, electrolyte and . This work expands upon the Gratzel solar cell with a dye in TiO2. Due to various structural and optical characteristics, zinc(hydr)oxide (Zn(OH)2) and its porous composites with 2% and 5% graphite oxide(GO) can be used for various applications including the manufacture of various , protective elements in electric and electronic appliances, as gas-sensors, catalysts, in cosmetics a UV light absorber, and solar cells. In this research, both TiO2 and zinc(hydr)oxide (refer as Zn(OH)2 ) and its porous composites with 2% and 5% graphite oxide(GO) (refer as ZnGO-2 and ZnGO-5 respectively) have been studied with photoactive quantum dots (QDs). The goal of this research was to understand the optical properties of Zn (OH)2, ZnGO-2 and ZnGO-5 (i.e. We determined the band gap of these three materials using absorptions, photoluminescence and photo-conductivity), structural characterizations of these three samples (i.e.We determined critical points transitions), time resolved fluorescence of these three materials, (i.e. We determined the lifetime of the carrier, the rise time of the carrier, relaxation, and carrier density using new model) and application in the Gratzel like quantum dots (QDs) sensitized hybrid Zn(OH)2/ZnGO solar cells compared with TiO2 which made with QD(CdSe and PbS ).The main objective of this thesis was to develop hybrid solar cell with Zn(OH)/ZnGO material and TiO2 to make alternative designs for the fabrication of quantum dots sensitized Zn(OH)/ZnGO hybrid solar cells that can enhance the efficiencies as well as reduce the cost by making it more amenable to large scale production. In hybrid solar cells, the role of the conductive glass substrate with the performance of Zn(OH)2/ZnGO/QD(CdSe and/or PbS) /Electrolyte or Perovskite based photovoltaic devices, as well as fabricate new photovoltaic devices, to improve the efficiencies in power. The focus of this doctoral thesis was to introduce new composite material such as Zn(OH)2 with QDs CdSe(visible), PbS(UV and NIR) for their applications in new solar cells which incorporate energy transfer processes in order to improve light harvesting.The basic idea to obtain maximum energy efficiency is to absorb most of the solar spectrum in the 3 zones: UV, visible and NIR light. The photoexcitation and processes involved with carriers excitons and multiexcition generations in uv

Clinical presentations among adult patients with tuberculous meningitis

Background: Bangladesh is a country with a high burden of pulmonary as well as extrapulmonary tuberculosis. TBM is a particularly important public health issue in our country. Identifying prognostic predictors would improve the quality of management and ultimately will prevent long-term mortality and morbidity. The aim of the study was to observe and identify the most common clinical presentations among patients with tuberculous meningitis. Methods: This hospital-based prospective cohort study was carried out at the in-patient Department of Clinical Neurology at the National Institute of Neurosciences and Hospital (NINS and H), Dhaka, Bangladesh from October 2016 to September 2017, 1 year. A total of 54 patients admitted to the hospital with features of tuberculous meningitis (TBM) were selected for the study following inclusion and exclusion criteria. Results: Over 70% of patients were adolescents or young adults with a mean age of 28.2±12.3 years. The majority (48.2%) of the participants were from TBM stage II, while 37% were from stage III of TBM. Fever, headache, and systematic symptoms were the most frequent clinical presentations. The median delay in treatment was 30 days. Interruption in anti-TB treatment was reported in 3 (9.3%) cases. Conclusions: The study found that among possible TBM cases, the most frequent clinical features were fever, headache, and systematic symptoms. Focal neurological deficit and cerebral nerve palsy also had a high prevalence among the participants. The majority of the participants were young adults and female prevalence was high in the present study. The majority were from stage II TB among the study participants

Compositional Changes in Colostrum of Crossbred Dairy Cow

The research was conducted to examine the day-to-day variation in colostrum composition at the udder quarter level. For this purpose, a total of 3 Holstein Frisian crossbred cows were selected from Bangladesh Agricultural University Dairy Farm. Colostrum samples were collected both as mixed and separately from different teats. The concentration of major colostrum constituents (fat, protein, lactose, total solids, solids-not-fat, ash, pH, specific gravity) changed significantly (p≤0.05), the levels on day 4 were found similar to those of normal milk. The highest mean value of fat, protein, total solid, SNF, ash and specific gravity in colostrum was observed on 1st post-partum day as 6.02±0.70, 14.20±0.18, 23.88±1.25, 17.94±0.42, 1.03±0.05% and 1.05±0.00, respectively and later on, decreased as postpartum days advanced. Minimum average fat, protein, total solid, SNF, and ash content in colostrum was observed on 5th postpartum days as 3.75±0.11, 3.24±0.08, 12.00±0.20, 8.27±0.16% and 0.695±0.01, respectively. But lactose percent and pH showed an increasing trend from 1 to 5 postpartum days. Minimum average lactose and pH was observed on 1st and 5th postpartum days as 2.42±0.06%; 6.03±0.04% and 4.26±0.15; 6.30±0.04, respectively. The quality of colostrum produced by udder quarters was found significantly different (p<0.05). The rear quarters produced colostrum, which was significantly richer in fat, proteins, TS, pH compared to forequarters colostrum. The forequarters produced colostrum which was significantly richer in lactose, ash, SNF compared to forequarters colostrum. In conclusion, the results showed that colostrum composition was significantly changed up to 5 days post-partum

Buffalo Milk Yield, Quality, and Marketing in Different Agro-Climatic Districts of Bangladesh

The study was aimed at assessing the productive performance of dairy buffalo and milk marketing approaches in different agro-climatic districts of Bangladesh. Three (03) districts of Bangladesh viz. Bhola, Mymensingh, and Dinajpur were chosen from the coastal, river basin and semi-arid region, respectively. A triangulation method of survey was used to collect the data and the components of the triangle were buffalo farms, buffalo farmers and buffalo herdsmen. The investigation duration was twelve (12) months. The study revealed that the highest milk yield (5 L/h/d; p=0.010) was found in the river basin and semi-arid region. Lactation yield was also recorded double in the river basin and semi-arid districts compared to coastal districts (p=0.000). In the case of lactation length, the river basin buffaloes possessed 33 and 36% longer than coastal and semi-arid districts, respectively. All the chemical components were found significantly different (p≤0.050) but fat. Among different agro-climatic districts, about 92% of milk was traded in the coastal region after meeting the household's need but it was noted that the farmers from the semi-arid region kept more than 21% of milk for family consumption (p=0.000). The highest unit price (BDT 72/L) of milk was observed in the river basin district (p=0.011). In conclusion, the current situations of buffalo farming and milk marketing approaches in Bangladesh, varies considerably

Stress Response Pathways in Dairy Cattle: A Brief Review

Stress is an external event or condition that places a strain on a biological system. The animal response to stress involves the expenditure of energy to remove or reduce the impact of stress. This increases the maintenance requirements of the animal and results in loss of production. The biological response to stress is divided into acute and chronic phases, with the acute phase lasting hours to a few days, and the chronic phase lasting several days to weeks. The acute response is driven by homeostatic regulators of the nervous and endocrine systems and the chronic phase by homeorhetic regulators of the endocrine system. Both responses involve alterations in energy balance and metabolism. The thermal environment affects all animals and therefore represents the largest single stressor in animal production. Other types of stressors include housing conditions, overcrowding, social rank, disease, and toxic compounds. "Acclimation" to stress is a phenotypic response developed by the animal to an individual stressor within the environment. Acclimation is a homeorhetic process that takes several weeks to occur and occurs via homeorhetic, not homeostatic, mechanisms. It is a phenotypic change that disappears when the stress is removed. Milk yield and reproduction are extremely sensitive to stress because of the high energy and protein demands of lactation and the complexity of the reproductive process and multiple organs that are involved. Improvements in the protection of animals against stress require improved education of producers to recognize stress and methods for estimating the degree of stress on animals

Variations of Raw Milk Components and Amino Acid Profiles in Different Dairy Buffalo Crossbreds

This study aimed to assess the relationship between milk components and amino acid (AA) profiles among different buffalo crossbreds in Bangladesh. A total of thirty-six (36) lactating buffaloes were selected from Murrah, Nili-Ravi, and Mehsana crossbreds, and they were assigned to 03 groups, each with 12 buffaloes. The total experimental period was 10 weeks, including the initial 10 days of diet adjustment. The results from the experiment revealed that milk protein, fat, and total solids contents of Murrah crossbred was significantly (p<0.05) higher than Mehsana and Nili-Ravi crossbreds. In contrast, the lactose content of all buffalo crossbreds was statistically similar (p>0.05). In the case of milk amino acid contents, all the milk samples entailed a higher concentration of Glutamic acid (0.9-1.00 g/100 g of milk), whereas Cysteine had the lowest concentration (0.02-0.05 g/100 g). The most prevalent essential amino acids were Leucine, Lysine, and Phenylalanine, whereas the most prevalent non-essential amino acids were Glutamic acid, Proline, Asparagine, and Serine. Lysine, Isoleucine, Leucine, Phenylalanine, Cysteine, and Histidine concentrations differed significantly (p<0.05), and at the same time as the other 11 AAs concentrations were found non-significant (p>0.05). The highest Lysine: Methionine ratio observed in Murrah buffalo was about 3.20%, while in Mehsana and Nili-Ravi buffalo was about 2.80 and 2.50%, respectively. Thus, it was evident from the study that the raw milk components and amino acid composition vary considerably in the different lactating buffalo crossbreds. Finally, the compositional data of raw milk may create the way of sustainable use of milk from dairy buffalo crossbreds and improve food and nutrition security, particularly in developing countries

COMPARATIVE STUDY OF PROFESSIONALISM OF FUTURE MEDICAL PROFESSIONALS AMONG THREE PRIVATE MEDICAL COLLEGES OF BANGLADESH

Objectives: Medical professionalism forms the bridge between doctors and society. Conserving and maintaining professionalism is obligatory for physician curriculum. The objective of this study was to scrutinize and compare the professionalism of future medical professionals among different medical institutes. Methodology: It was a cross-sectional study conducted on 332 year-III and year-IV MBBS students of session 2012-2013 from three private medical colleges in Bangladesh. Data was collected using a mixed validated instrument containing items under fundamental elements of professionalism, measured by 5-points Likert scale giving a maximum score of 220. Results: Among 332 respondents, 44% were male, 56% female; Year-III respondents constituted 51% and Year-IV constituted 49%. Mean professionalism scores for male and female were 176.21 and 175.33, while for Year-III and Year-IV were 174.96 and 176.50 respectively. No significant differences observed between gender and year of study. However, significant differences were noticed between year-IV male students among three medical colleges. Majority (83%) students were imprecise of professionalism. Conclusions: Lack of focus is a worry for professionalism. Educators should focus on fundamental elements of professionalism. KEYWORDS: Professionalism, Medical-student, Core-values, Comparisons, Bangladesh

Perception of tomorrow’s Health-Care connoisseur and front-runners of their educational environment utilizing DREEM inventory in Bahasa Melayu version, the native language of Malaysia

Background There have been a lot of reports throughout the world that medical students were abused during their undergraduate education and clerkship training. Thereafter, calls for intensifying the evaluation of medical and health schools’ curricula based on students’ perceptions of their educational environment. Several studies, methods, and instruments were developed including the Dundee Ready Education Environment Measure (DREEM) inventory, to evaluate the medical educational environment in last five decades. The DREEM inventory has been translated into minimum eight different native tongues namely Arabic, Chinese, Japanese, Persian, Portuguese, Spanish, Swedish, and Turkish. Aims The objective of this study was to assess the educational environment of the UniSZA undergraduate medical program from the students’ perspective utilizing the DREEM inventory translated in Bahasa Melayu. Methods This was a descriptive cross-sectional survey conducted among the medical students of session 2015-2016 to assess educational environment of the Faculty of Medicine, UniSZA. The study was conducted from December 2015 to January 2016. Universal sampling technique was adopted. Results A total of 277 (95.5 per cent) out of 290 students responded to the questionnaire; among them 27.4 per cent were male and 72.6 per cent were female respondents. The overall mean DREEM scores for both preclinical and clinical students were 67.41±24.06. The scores for pre-clinical and clinical were 64.02±25.10 and 69.65±23.15 respectively; however, no statistically significant (p=0.57) differences was observed between two phases. A significant difference was observed between gender of the respondents in students’ perceptions of teachers (p=0.005) and students’ social self-perceptions (p=0.046)

Internet use and addiction among medical students of Universiti Sultan Zainal Abidin,Malaysia

The use of Internet has now become indispensable, and the technology has revolutionized the medical education and practice worldwide. Currently, medical students and professionals have an enormous opportunity to keep them always updated with the exponential growth of knowledge because of potential progression of Internet throughout the world that enables them to become a lifelong learner. Internet addiction is a widespread phenomenon among students and academicians at universities in Malaysia. Students use the Internet for recreational purpose and personal and professional development. The Internet has become an integral part of day-to-day life of the university students, including medical students. The aim of the present study was to examine the Internet use and addiction among students of Universiti Sultan Zainal Abidin, Malaysia. Methods: This was a cross-sectional study in which a questionnaire, Internet Addiction Diagnostic Questionnaire, developed by the Center for Internet Addiction, USA, was used. One hundred forty-nine medical students of Universiti Sultan Zainal Abidin participated in this study. Data were analyzed using Statistical Package for the Social Sciences software. Results: The mean scores were 44.9±14.05 and 41.4±13.05 for male and female participants, espectively, which indicated that both the genders were suffering from mild Internet addiction. Conclusion: This study shows almost similar level of Internet usage among medical students irrespective of their socioeconomic background, with no statistically significant (p>0.05) differences, except among the years of study (p=0.007). Overall, from the research data and having worked with this cohort very closely, Universiti Sultan Zainal Abidin medical students can be labeled as wonted and recurring users of the Internet. Nevertheless, it is very difficult to define as Internet addicts or pathological users of the Internet because of small sample size and cross-sectional study

Availability and price changes of potential medicines and equipment for the prevention and treatment of COVID-19 among pharmacy and drug stores in Bangladesh; findings and implications

Objective: There are concerns with increased prices and drug shortages for pertinent medicines and personal protective equipment (PPE) to prevent and treat COVID-19 enhanced by misinformation. Community pharmacists and drug stores play a significant role in disease management in Bangladesh due to high co-payments. Consequently, a need to review prices and availability in the pandemic. Materials and Methods: Multiple approach involving a review and questionnaire among pharmacies and stores early March to end May 2020. Results and Discussion: 170 pharmacies and drug stores took part, giving a response rate of 63.9%. Encouragingly, no change in utilization of antimalarial medicines in 51.2% of stores despite global endorsements. However, increased utilisation of antibiotics (70.6%), analgesics (97.6%), vitamins (90.6%) and PPE (over 95%). Encouragingly, increases in purchasing of PPE. No increase in prices among 50% of the stores for antimalarials, with a similar situation for antibiotics (65.3%), analgesics (54.7%), and vitamins (51.8%). However, price increases typically for PPE (over 90% of stores). Shortages also seen for medicines and PPE, again greater for PPE. Conclusions: The pandemic has impacted on the supply and prices of medicines and PPE in Bangladesh. Key stakeholder groups can play a role addressing misinformation, with enhanced local production helping address future shortages and prices