Feasibility analysis of turbocharger based micro gas turbine engine.

PhD ThesisThe research involves a feasibility study of micro gas turbine (MGT) performance. The engine is based on off-the-shelve turbochargers provided by Cummins Turbo Tech Ltd (project sponsor). The intended applications of the MGT are: hybrid electric vehicles (HEV) and small portable power-plant (SPP). A market research was initially conducted to assess the scope for MGT. Following this, a preliminary parametric design point (DP) study, using an in-house modified code, has been performed on relevant Brayton cycles to choose the optimum DP in contrast to the market research. It was followed by a full off-DP (ODP) analysis. Actual component maps were used to model the output. Analysing the holistic DP and ODP parametric studies, an optimum cycle has been defined. A full thermo-economic analysis was conducted for this cycle to evaluate the applicability of the final MGT for HEV or SPP. Following this, a vehicle performance analysis has been conducted using the final MGT performance maps. Models capable of analysing HEV thermodynamic and kinematic performance were developed using a Simulink based analysis tool called QSS. The performance has been compared with other HEVs and standard vehicle output. A comparative analysis has been presented to assess the MGT based HEV performance. Following the above performance analyses, an experimental study has been pursued to investigate the effects of swirler, primary jets and various side-entry injection mechanisms on combustor flame-tube aerodynamics. Results show the influence of these factors on primary zone recirculation and exit plane pressure and axial velocity distribution. These factors are crucial for efficient combustion. A mathematical model for the recirculation zone has also been devised based on the empirical findings. Future scopes of the project, such as: further studies on flame tube aerodynamics of the sideentry combustor, MGT test rig setup, and heat-exchanger testing, have been described

Prevalence and demographic, socioeconomic, and behavioral risk factors of self-reported symptoms of sexually transmitted infections (STIs) among ever-married women : evidence from nationally representative surveys in Bangladesh

Sexually transmitted infections (STI) symptoms (e.g., abnormal genital discharge and genital sores/ulcers) are a major public health concern in Bangladesh because the symptoms can indicate an STI and cause sexual and reproductive health complications in women of reproductive age. To our knowledge, no study examined the prevalence and risk factors of STI symptoms using a nationally representative sample. This study investigates the prevalence of STI symptoms among ever-married women in Bangladesh and the associations of STI symptoms with various demographic, socioeconomic, and behavioral risk factors using the most recent available data (2007, 2011, and 2014) of the Bangladesh Demographic and Health Surveys (BDHS). The BDHS employs a two stage stratified sampling technique. The analytic sample comprised 41,777 women of reproductive age (15–49 years). Outcome variables included STI symptoms: abnormal genital discharge and genital sores/ulcers. Multivariate logistic regression was employed to find the adjusted odds ratio with a 95% confidence interval to assess the associations of outcome measures with explanatory variables. The study found that the prevalence of abnormal genital discharge and genital sores/ulcers among ever-married women aged 15–49 years was 10% and 6%, respectively. Multivariable analysis revealed that for women aged 25–34 years, those who used contraceptives and married earlier had an increased likelihood of STI symptoms. Furthermore, women from the wealthiest wealth quintile and couple’s joint decision-making were less likely to have STI symptoms. Findings have implications for interventions efforts aiming to improve women’s sexual and reproductive health in Bangladesh

Morphological responses of three contrasting Soybean (Glycine max (L.) Merrill) genotypes under different levels of salinity stress in the coastal region of Bangladesh

Soil salinity, a global environmental issue, inhibits plant development and production. Soybean is an economically important legume crop whose yield and quality are highly affected by excessive levels of salt in the root zone. A factorial experiment was conducted in a net house from October 2019 to January 2020 to evaluate the performance of three distinct soybean genotypes under varying levels of salinity stress. The experiment followed a completely randomized design (CRD) with three replications. Three soybean cultivars, namely BINA Soybean 1, BINA Soybean 2, and BINA Soybean 4 were used in this experiment. The soil salinity treatments were 0 mM NaCl, 50 mM NaCl, 100 mM NaCl, 150 mM NaCl, and 200 mM NaCl. The electrical conductivity (EC) of the soil sample was 0.91dS/m. Six seeds were sown 3 cm deep in each pot. A total of 45 pots were used in this experiment. The performance of each variety was evaluated based on its germination percentage, time of germination, no. of branches/plant, no. of leaves/plant, no. of flowers/plant, plant height (cm), no. of pods/plant, pod length (cm), seeds/pod, and root length (cm). Based on the results obtained from this research trial, it can be inferred that the BINA Soybean 2 variety along with 0 mM NaCl, 50 mM NaCl, and 100 mM NaCl treatments exhibited superior performance in all parameters compared to the other varieties. This study provides clear evidence that the soybean, particularly the BINA Soybean 2 variety, holds significant promise as a crop suitable for coastal regions. Furthermore, it suggests that the cultivation of soybeans in such areas could potentially enhance agricultural productivity, particularly in the presence of mild saline conditions. Nevertheless, it exhibits limited growth potential in environments with elevated salinity levels

Safety and effi cacy of alternative antibiotic regimens compared with 7 day injectable procaine benzylpenicillin and gentamicin for outpatient treatment of neonates and young infants with clinical signs of severe infection when referral is not possible: a randomised, open-label, equivalence trial

Background Severe infections remain one of the main causes of neonatal deaths worldwide. Possible severe infection is diagnosed in young infants (aged 0–59 days) according to the presence of one or more clinical signs. The recommended treatment is hospital admission with 7–10 days of injectable antibiotic therapy. In low-income and middle-income countries, barriers to hospital care lead to delayed, inadequate, or no treatment for many young infants. We aimed to identify eff ective alternative antibiotic regimens to expand treatment options for situations where hospital admission is not possible. Methods We did this randomised, open-label, equivalence trial in four urban hospitals and one rural fi eld site in Bangladesh to determine whether two alternative antibiotic regimens with reduced numbers of injectable antibiotics combined with oral antibiotics had similar effi cacy and safety to the standard regimen, which was also used as outpatient treatment. We randomly assigned infants who showed at least one clinical sign of severe, but not critical, infection (except fast breathing alone), whose parents refused hospital admission, to one of the three treatment regimens. We stratifi ed randomisation by study site and age (<7 days or 7–59 days) using computer-generated randomisation sequences. The standard treatment was intramuscular procaine benzylpenicillin and gentamicin once per day for 7 days (group A). The alternative regimens were intramuscular gentamicin once per day and oral amoxicillin twice per day for 7 days (group B) or intramuscular procaine benzylpenicillin and gentamicin once per day for 2 days, then oral amoxicillin twice per day for 5 days (group C). The primary outcome was treatment failure within 7 days after enrolment. Assessors of treatment failure were masked to treatment allocation. Primary analysis was per protocol. We used a prespecifi ed similarity margin of 5% to assess equivalence between regimens. This study is registered with ClinicalTrials.gov, number NCT00844337. Findings Between July 1, 2009, and June 30, 2013, we recruited 2490 young infants into the trial. We assigned 830 infants to group A, 831 infants to group B, and 829 infants to group C. 2367 (95%) infants fulfi lled per-protocol criteria. 78 (10%) of 795 per-protocol infants had treatment failure in group A compared with 65 (8%) of 782 infants in group B (risk diff erence –1·5%, 95% CI –4·3 to 1·3) and 64 (8%) of 790 infants in group C (–1·7%, –4·5 to 1·1). In group A, 14 (2%) infants died before day 15, compared with 12 (2%) infants in group B and 12 (2%) infants in group C. Non-fatal relapse rates were similar in all three groups (12 [2%] infants in group A vs 13 [2%] infants in group B and 10 [1%] infants in group C). Interpretation Our results suggest that the two alternative antibiotic regimens for outpatient treatment of clinical signs of severe infection in young infants whose parents refused hospital admission are as effi cacious as the standard regimen. This fi nding could increase treatment options in resource-poor settings when referral care is not available or acceptable

Causes and incidence of community-acquired serious infections among young children in south Asia (ANISA): an observational cohort study.

BACKGROUND: More than 500 000 neonatal deaths per year result from possible serious bacterial infections (pSBIs), but the causes are largely unknown. We investigated the incidence of community-acquired infections caused by specific organisms among neonates in south Asia. METHODS: From 2011 to 2014, we identified babies through population-based pregnancy surveillance at five sites in Bangladesh, India, and Pakistan. Babies were visited at home by community health workers up to ten times from age 0 to 59 days. Illness meeting the WHO definition of pSBI and randomly selected healthy babies were referred to study physicians. The primary objective was to estimate proportions of specific infectious causes by blood culture and Custom TaqMan Array Cards molecular assay (Thermo Fisher, Bartlesville, OK, USA) of blood and respiratory samples. FINDINGS: 6022 pSBI episodes were identified among 63 114 babies (95·4 per 1000 livebirths). Causes were attributed in 28% of episodes (16% bacterial and 12% viral). Mean incidence of bacterial infections was 13·2 (95% credible interval [CrI] 11·2-15·6) per 1000 livebirths and of viral infections was 10·1 (9·4-11·6) per 1000 livebirths. The leading pathogen was respiratory syncytial virus (5·4, 95% CrI 4·8-6·3 episodes per 1000 livebirths), followed by Ureaplasma spp (2·4, 1·6-3·2 episodes per 1000 livebirths). Among babies who died, causes were attributed to 46% of pSBI episodes, among which 92% were bacterial. 85 (83%) of 102 blood culture isolates were susceptible to penicillin, ampicillin, gentamicin, or a combination of these drugs. INTERPRETATION: Non-attribution of a cause in a high proportion of patients suggests that a substantial proportion of pSBI episodes might not have been due to infection. The predominance of bacterial causes among babies who died, however, indicates that appropriate prevention measures and management could substantially affect neonatal mortality. Susceptibility of bacterial isolates to first-line antibiotics emphasises the need for prudent and limited use of newer-generation antibiotics. Furthermore, the predominance of atypical bacteria we found and high incidence of respiratory syncytial virus indicated that changes in management strategies for treatment and prevention are needed. Given the burden of disease, prevention of respiratory syncytial virus would have a notable effect on the overall health system and achievement of Sustainable Development Goal. FUNDING: Bill & Melinda Gates Foundation

Effect of mixed leaf litter of four mangrove species on shrimp post larvae (Penaeus monodon, Fabricius, 1798) performance in tank and mesocosm conditions in Bangladesh

Mangrove leaf litter is a potential source of nutrients for shrimp post larvae. To introduce mangrove trees in shrimp farms it is necessary to identify the combination of trees which is most beneficial for shrimp. The present study evaluated the effects of mixed leaf litter of four mangrove species (Avicennia officinalis (Ao), Sonneratia apetala (Sa), S. caseolaris (Sc) and Heritiera fomes (Hf) on shrimp post larvae performance and water and soil quality. Leaf litter with and without supplemental feed was applied to shrimp culture tanks according to a 4 × 2 factorial design and followed by testing a subset of treatments in mesocosm pond conditions. Shrimp post larvae of 15-days old (PL15) with an average weight of 0.01 g were used for both experiments, each with a 4-week duration without water exchange. Under controlled conditions in the tanks, leaf litter and feed resulted in 22 to 32% higher weight gain of PL shrimp than combined weight gain realized when receiving only leaf litter or only feed, indicating synergism. Based on this, the pond experiment was designed with combined application of leaf litter and feed. The pond experiment resulted in higher shrimp weight gain than realized in the tanks. In tanks, the highest average individual weight gain of PL was observed for the leaf litter mixture SaAoHf (0.23 g)followed by SaScHf (0.21 g), ScAoHf (0.21 g) andSaScAoHf (0.20 g). Paralleling the results of the tank experiment, SaAoHf leaf litter also gave the highest average individual weight gain (1.2 g) of PL shrimpin the ponds but other leaf litter treatments followed by SaScAoHf (0.95 g), ScAoHf (0.84 g) and SaScHf (0.69 g) leaf litter. The different mixtures of mangrove leaf litter also resulted in significant differences in biological oxygen demand (BOD5), phytoplankton and zooplankton concentrations in pond water and organic carbon in soil. Both phytoplankton (P < 0.01, Pearson correlation r = 0.910)and zooplankton (P < 0.05, r = 0.535) abundance was positively correlated to shrimp weight gain. The low feed conversion ratio (FCR) in the treatments combining leaf litter and supplemental feed as compared to treatments using only feed indicated extra food benefits for shrimp PL from decomposing leaf litter. Overall, mixed mangrove leaf litter had a positive effect on shrimp performance and this effect was highest for SaAoHf leaf litter

Mangrove forest conservation vs shrimp production : Uncovering a sustainable co-management model and policy solution for mangrove greenbelt development in coastal Bangladesh.

Mangrove forests are remarkably diverse and productive ecosystems, with distinctive biophysical environments in intertidal coastal regions of the tropics and subtropics. In these regions, shrimp cultivation is identified as a profitable business and one of the main reasons for clearing of mangroves to construct shrimp farms. Against this backdrop and based on the first author's previous PhD research and other relevant scholarly works, in this commentary we discuss the aspects and contexts of the mangrove-based integrated shrimp farming system. Then, we recommend a model of co-management and a set of policy option towards sustainable silvo-aquaculture to protect/restore the mangrove forests and sustain shrimp production in coastal areas of Bangladesh. Mangrovesand shrimp culture are not necessarily incompatible. Many mangrove species have been identified as beneficial for shrimp culture for a number of possible reasons. Most importantly, the nutrients in the leaf litter of several mangrove species have been found to enhance natural food production for shrimp. Besides the nutrient input, the leaf litter also provides surface area for biofilm development, on which different life stages of shrimp can graze. In addition, the combination of mangrove leaf litter and feed has been shown to enhance shrimp productionsynergistically. Additional economic benefits from mangrove-shrimp co-management include the production of timber (e.g. buildings, boats and fuel woods) and non-timber products (e.g. fruits, honey, fibers, firewood, resinsand bark). Thus, mangrove-based aquaculture or silvo-aquaculture system can be considered as a nature-based solution to sustainably revitalize the economy in coastal areas where shrimp has been the economic mainstay. Though there are positive effects, we point out some potential negative impacts of mangrove-based shrimp culture, like the anti-nutrients content in the leaf litter, which might impact shrimp production. In addition, the long term use of mangrove leaf litter might degrade the water quality. Therefore, the co-management policyrecommends a controlled practice of mangroves in shrimp culture to balance conservation of mangrove-based ecology and profitable shrimp production. The approach promotes nature-based solutions and fosters sustain-able pathways for food production, considering socio-economic and environmental dynamic

Synergistic effects of mangrove leaf litter and supplemental feed on water quality, growth and survival of shrimp (Penaeus monodon, Fabricius, 1798) post larvae

Shrimp based mangrove-aquaculture (silvo-aquaculture) is practiced in many countries of the world and leaf litter of different mangrove tree species is a potential nutrient source in these systems. The present study evaluated the effects of mangrove leaf litter from four mangrove species (Sonneratia apetala, S. caseolaris, Avicennia officinalis and Heritiera fomes) on the production of juvenile shrimp (Penaeus monodon) with and without supplemental feed. Fifteen-day-old post larvae (PL15) with an average weight of 0.01 g were reared in 1100 L fibre-reinforced polyethylene tanks containing 1000 L of 10 ppt saline water and a water depth of 0.9 m. Leaf litter with or without supplemental feed was applied to the tanks according to a 4 × 2 factorial design. The PLs were stocked at a density of 100 per tank and the experiment was conducted for 4 weeks without any exchange of water. Both mangrove species and feed application affected shrimp performance and water quality parameters except dissolved oxygen (DO), chemical oxygen demand (COD) and zoo-plankton concentration. The average survival rate of juvenile shrimp ranged from 86 to 94% in the treatments with both leaf litter and feed, 75–82% in the treatments with only leaf litter and 88% in the treatment with only feed. However, 100% mortality was observed in the treatment without any leaf litter or supplemental feed. Combined, leaf litter and feed resulted in 21 to 33% higher weight gain of shrimp PL than based on the combined contributions of leaf litter only or feed only, indicating synergism. Among the different mangrove species, S. apetala (23.1%) contributed the highest to total weight gain followed by A. officinalis (21.6%), S. caseolaris (21.6%) and H. fomes (10%). The lower feed conversion ratio (FCR) (0.18–0.27) in the treatments combining leaf litter and supplemental feed as compared to the feed-only treatment (0.41) indicated that leaf litter (directly or by stimulating natural food production) contributed to supplemental feeding. The growth of phytoplankton also appeared to contribute in low FCR as evidenced by a positive correlation (P < 0.001, r = 0.681⁎⁎) between phytoplankton concentration and shrimp weight gain. The synergistic effect between leaf litter and supplemental feed can help the farmer to minimize the shrimp production cost by lowering the feed input and enhancing mangrove three coverage on pond dikes as an inexpensive source of natural food