A Comparative Study of Natural Gas and Biogas Combustion in A Swirling Flow Gas Turbine Combustor

In this study, non-premixed combustion of a traditional fuel-natural gas, and an alternative fuel-biogas, is simulated in a swirling flow industrial gas turbine combustor geometry which includes the combustor liner and the outside casing in order to replicate the flow and combustion in a real gas turbine combustor. The 3D combustion simulations are validated and the results for combustion of both gases are analyzed to compare and evaluate the viability of biogas as an alternative fuel for use in industrial gas turbine combustors. The combustion performance is evaluated based on multiple combustion performance optimization parameters, namely, the combustion efficiency, pattern factor, and pollutant emissions (CO and NO). The effects of two design parameters: swirl number and fuel injector diameter on the combustion performance optimization parameters are examined. The results have been analyzed to identify the best case for each combustion performance optimization parameter and a suitable trade-off case for both gases is proposed. Additionally, the comparison of the combustion performances of both gases revealed that despite possessing much lower methane and hence lower heating value (LHV), a combination of swirl number and fuel injector diameter for biogas of a specific composition results in a combustion performance comparable to natural gas along with lower NO emission, although at the expense of higher CO emission. Therefore, biogas can potentially be utilized as an alternative fuel in industrial gas turbine combustors, and methods for reducing CO emission can be devised.Peer ReviewedPostprint (published version

An Investigation of RANS Simulations for Swirl-Stabilized Isothermal Turbulent Flow in a Gas Turbine Burner

The presence of complex flow features in swirling flows have made it an essential part of many engineering applications. These features can only be accurately predicted by the DNS or LES type methods which are highly expensive in terms of resources and time. This fact established the RANS approach as the key method in the industrial arena because of its modest requirement of resources unlike LES. However, existing RANS investigations on swirl-stabilized isothermal turbulent flow are 2D and lack credibility on the question of predicting the prominent flow features which exist in swirling flows. The current study investigates the 3D RANS simulations in predicting a swirl-stabilized isothermal turbulent flow in a burner for a gas-turbine combustion chamber which possesses complex flow features such as bluff-body induced recirculation zone and Vortex Breakdown (VB) bubble. Current investigations also assess the establishment of 3D RANS simulations as a viable industrial alternative to the computationally expensive LES and the less accurate 2D RANS simulations. Furthermore, the influence of mesh quality, different turbulence models, discretization schemes on the accuracy of the predictions are examined. It was found that the multi-zonal mesh with hexahedron cells had the highest mesh quality and produced the best results, and the standard k-¿ model predicted all the flow features with default schemes in ANSYS-Fluent. The conclusions in the paper are valuable, practical and will save a lot of time and effort of practicing engineers during the numerical modelling setup selection stages for solving such complex three-dimensional flow problems. KEYWORDS: 3D RANS, industrial alternative, swirl, burner, recirculation, vortex breakdown, bluff-body, iso-thermal, turbulence.Award-winningPostprint (published version

Burden and features of neurological patients in Chittagong Medical College and Hospital in Bangladesh

Background: Neurological disorders are a common and significant public health problem globally, and innovative strategies are needed to address the epidemic in resource-poor settings in Bangladesh. The aim of this study was to evaluate the burden and features of neurological diseases requiring hospitalization in a tertiary care hospital in Chittagong, Bangladesh. Methods: This study was a prospective observational study conducted from January to June 2021 on patients admitted to the adult neurology unit of a hospital in Chittagong, Bangladesh. Data was collected through face-to-face interviews, laboratory data, and previous medical records, and in-hospital complications and outcomes were recorded. The data was cleaned and analysed using SPSS and presented in tables. Results: In this study, stroke was the most common neurological condition requiring hospitalization, accounting for 74% of cases and leading to death in 73% of cases. The most frequent in-hospital complication was urinary tract infection (26%), mostly in stroke patients. Of stroke patients, 88% had incomplete recoveries at discharge, while 7% died. Hypertension was the most common risk factor present in both acute confusional state and stroke cases. The median duration of hospital stay was longest among patients with central nervous system infections. Conclusions: Stroke dominates the burden of neurological diseases requiring hospitalization in tertiary care hospitals in Bangladesh. The most frequent in-hospital complication was urinary tract infections, mostly in stroke cases. The overall in-hospital mortality was 7%, most patients recovered incompletely at discharge (82%)

Timing of Enteral Feeding in Cerebral Malaria in Resource-Poor Settings: A Randomized Trial

BACKGROUND: Early start of enteral feeding is an established treatment strategy in intubated patients in intensive care since it reduces invasive bacterial infections and length of hospital stay. There is equipoise whether early enteral feeding is also beneficial in non-intubated patients with cerebral malaria in resource poor settings. We hypothesized that the risk of aspiration pneumonia might outweigh the potential benefits of earlier recovery and prevention of hypoglycaemia. METHOD AND FINDINGS: A randomized trial of early (day of admission) versus late (after 60 hours in adults or 36 hours in children) start of enteral feeding was undertaken in patients with cerebral malaria in Chittagong, Bangladesh from May 2008 to August 2009. The primary outcome measures were incidence of aspiration pneumonia, hypoglycaemia and coma recovery time. The trial was terminated after inclusion of 56 patients because of a high incidence of aspiration pneumonia in the early feeding group (9/27 (33%)), compared to the late feeding group (0/29 (0%)), p = 0.001). One patient in the late feeding group, and none in the early group, had hypoglycaemia during admission. There was no significant difference in overall mortality (9/27 (33%) vs 6/29 (21%), p = 0.370), but mortality was 5/9 (56%) in patients with aspiration pneumonia. CONCLUSIONS: In conclusion, early start of enteral feeding is detrimental in non-intubated patients with cerebral malaria in many resource-poor settings. Evidence gathered in resource rich settings is not necessarily transferable to resource-poor settings. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN57488577

Annual Incidence of Snake Bite in Rural Bangladesh

Snake bite is one of the major causes of morbidity and mortality in many rural tropical areas. As a neglected public health problem, estimate of the risk is largely unknown. However, the associated personal and economic impact of snake bite is substantial across developing countries. This national survey investigated the risk and consequences of snake bite among the rural Bangladeshi population. We surveyed 18857 individuals from 24 out of 64 districts in Bangladesh where 98 snake bites including one death were reported. The estimated incidence density of snake bite is 623.4/ 100,000 person years (95% CI: 513.4–789.2/100,000 person years). Biting occurs mostly when individuals are at work. The majority of the victims (71%) received snake bites to their lower extremities. Eighty-six percent of the victims received some form of management within two hours of snake bite, although only three percent of them went directly to either a medical doctor or a hospital. The observed rate of snake bite in rural Bangladesh is substantially higher than anticipated. This coupled with poor access to health services led to an increase in related morbidity and mortality. An improvement in public health actions is therefore warranted

A descriptive study of Forcefully Displaced Myanmar Nationals (FDMN) presenting for care at public health sector hospitals in Bangladesh

Background In 2017 hundreds of thousands of ‘Rohingya’ fled to camps for Forcefully Displaced Myanmar Nationals (FDMN) in Cox’s Bazar, Bangladesh. Objective To describe the FDMNs presenting for care at public health facilities in Bangladesh so as to understand the health problems faced by the FDMNs and the burden on these public health facilities. Methods This study combined a retrospective review of existing hospital and clinic data with prospective surveillance in government health care centres. Findings The retrospective data showed a 26% increase in the number of consultations at the Kutupalong community clinic, the primary health facility closest to the camps, from 19,567 in 2015 to 26,309 in 2019. There was a corresponding 11% increase in admissions to health facilities in the area, from 80,991 in 2017 to 91,424 in 2019. Prospective surveillance of 9,421 FDMNs seeking health care from July 2018 to December 2019 showed that 29% had an infectious disease, 20% nutritional problems, 12% pregnancy-related conditions and 7% trauma or injury. Conclusions Great uncertainty remains regarding the return of FDMN to their home country of Myanmar. The current on-going protests following the military coup adds further insecurity to the status of the Rohingya. The presence of a large migrant population relative to a smaller host community burdens the limited facilities and resources of the public health sector. Continued support by the international public health community and civil society organizations is needed

COMO É QUE OS ESTUDANTES DE MEDICINA E ENFERMAGEM VEEM A TECNOLOGIA DE SAÚDE? UM ESTUDO DE VALIDAÇÃO PSICOMÉTRICA DO QUESTIONÁRIO DE AVALIAÇÃO DE USABILIDADE EM BANGLADESH

The modernization of healthcare delivery is a reality in various international settings. To ensure efficient and safe use of the diverse forms of healthcare technology available, professionals and students must be receptive to incorporating such tools into their practice. Currently, there is no instrument in Bangladesh to assess healthcare students’ technology acceptance. Objective: To translate, culturally adapt, and validate the Usability Evaluation Questionnaire (UtEQ) among Bangladeshi healthcare students. Method: A cross-sectional study with a methodological approach was conducted in two phases. The first phase involved the translation of the UtEQ questionnaire to Bengali, following the six stages proposed by Beaton et al. In the second phase, the psychometric properties of the questionnaire were evaluated using a non-probability sample of 486 undergraduate healthcare students from three higher education institutions in Bangladesh. Confirmatory factor analysis was performed, and the Cronbach’s alpha coefficient was estimated to find out the internal consistency. Results: Internal consistency was found to be excellent for all scale dimensions, ranging from 0.88 to 0.92, while confirmatory factor analysis showed adequate goodness-of-fit indicators. Conclusion: The UtEQ-B provides a reliable and valid method for healthcare educators and researchers to assess technology acceptance among healthcare students during clinical training in Bangladesh.A modernização da prestação de cuidados de saúde é uma realidade em vários contextos internacionais. Para garantir a utilização eficiente e segura das diversas formas de tecnologia em saúde disponíveis, os profissionais e estudantes devem estar receptivos à incorporação dessas ferramentas na sua prática. Atualmente, não existe em Bangladesh um instrumento para avaliar a aceitação da tecnologia pelos estudantes de saúde. Objetivo: Traduzir, adaptar culturalmente e validar o Questionário de Avaliação da Usabilidade (UtEQ) entre estudantes de saúde de Bangladesh. Método: Foi realizado um estudo transversal com uma abordagem metodológica em duas fases. A primeira fase envolveu a tradução do questionário UtEQ para bengali, seguindo as seis etapas propostas por Beaton et al. Na segunda fase, foram avaliadas as propriedades psicométricas do questionário usando uma amostra não probabilística de 486 estudantes de graduação em saúde de três instituições de ensino superior em Bangladesh. Foi realizada uma análise fatorial confirmatória e estimou-se o coeficiente alfa de Cronbach para verificar a consistência interna. Resultados: Foi encontrada uma consistência interna excelente para todas as dimensões da escala, variando de 0,88 a 0,92, enquanto a análise fatorial confirmatória mostrou indicadores adequados de ajuste. Conclusão: O UtEQ-B fornece um método confiável e válido para educadores e pesquisadores em saúde avaliarem a aceitação da tecnologia entre estudantes de saúde durante o treinamento clínico em Bangladesh

Retinal changes in visceral leishmaniasis by retinal photography

Background: In visceral leishmaniasis (VL), retinal changes have previously been noted but not described in detail and their clinical and pathological significance are unknown. A prospective observational study was undertaken in Mymensingh, Bangladesh aiming to describe in detail visible changes in the retina in unselected patients with VL. Methods: Patients underwent assessment of visual function, indirect and direct ophthalmoscopy and portable retinal photography. The photographs were assessed by masked observers including assessment for vessel tortuosity using a semi-automated system. Results: 30 patients with VL were enrolled, of whom 6 (20%) had abnormalities. These included 5 with focal retinal whitening, 2 with cotton wool spots, 2 with haemorrhages, as well as increased vessel tortuosity. Visual function was preserved. Conclusions: These changes suggest a previously unrecognized retinal vasculopathy. An inflammatory aetiology is plausible such as a subclinical retinal vasculitis, possibly with altered local microvascular autoregulation, and warrants further investigation. </p