Modeling and optimization of liquefied natural gas process

Ph.DDOCTOR OF PHILOSOPH

Translation and Validation of Enhanced Asian Rome III Questionnaires in Bengali Language for Diagnosis of Functional Gastrointestinal Disorders

Background/AimsFunctional gastrointestinal disorders (FGIDs), diagnosed by symptom-based criteria due to lack of biomarkers, need translated-validated questionnaires in different languages. As Bengali, the mother tongue of Bangladesh and eastern India, is the seventh most spoken language in the world, we translated and validated the Enhanced Asian Rome III questionnaire (EAR3Q) in this language.MethodsThe EAR3Q was translated in Bengali as per guideline from the Rome Foundation. The translated questionnaire was validated prospectively on Bengali-speaking healthy subjects (HS, n = 30), and patients with functional dyspepsia (FD, n = 35), irritable bowel syndrome (IBS, n = 40) and functional constipation (FC, n = 12) diagnosed by clinicians using the Rome III criteria. The subjects were asked to fill-in the questionnaire again after 2 weeks, to check for its reproducibility.ResultsDuring translation, the original and the backward translated English versions of the questionnaire demonstrated high concordance. Sensitivity of the Bengali questionnaire to diagnose patients with FD, IBS, FC, and HS was 100%, 100%, 75%, and 100%, respectively, considering diagnosis by the clinicians as the gold standard. On test-retest reliability analysis, Kappa values for FD, IBS, FC, and HS were 1.0, 1.0, 0.83, and 1.0, respectively. The Bengali questionnaire detected considerable overlap of FD symptoms among patients with IBS, IBS among patients with FD, and FD among patients with FC, which were not detected by the clinicians.ConclusionsWe successfully translated and validated the EAR3Q in Bengali. We believe that this translated questionnaire will be useful for clinical evaluation and research on FGIDs in the Bengali-speaking population

Safe distances between groundwater-based water wells and pit latrines at different hydrogeological conditions in the Ganges Atrai floodplains of Bangladesh.

BACKGROUND: Groundwater drawn from shallow tubewells in Bangladesh is often polluted by nearby pit latrines, which are commonly used toilets in rural and sub-urban areas of the country. METHODS: To determine the minimum safe distance of a tubewell from a pit latrine in different hydrogeological conditions of Bangladesh, 20 monitoring wells were installed at three study sites (Manda, Mohanpur and Bagmara) with the vertical and horizontal distances ranging from 18-47 to 2-15 m, respectively. Water samples were collected three times in three seasons and tested for faecal coliforms (FC) and faecal streptococci (FS) as indicators of contamination. Soil samples were analysed for texture, bulk density and hydraulic conductivity following standard procedures. Sediment samples were collected to prepare lithological logs. RESULTS: When the shallow aquifers at one of the three sites (Mohanpur) were overlained by 18-23-m-thick aquitards, the groundwater of the monitoring wells was found contaminated with a lateral and vertical distances of 2 and 31 m, respectively. However, where the aquitard was only 9 m thick, contamination was found up to lateral and vertical distances of 4.5 and 40.5 m, respectively. The soil textures of all the sites were mainly composed of loam and sandy loam. The hydraulic conductivities in the first aquifer at Manda, Mohanpur and Bagmara were 5.2-7.3, 8.2 and 1.4-15.7 m/h, respectively. CONCLUSIONS: The results showed that the safe distance from the tubewell to the pit latrine varied from site to site depending on the horizontal and vertical distances of the tubewell as well as hydrogeological conditions of a particular area

Enhancement of mechanical and corrosion resistance properties of electrodeposited Ni–P–TiC composite coatings

In the present study, the effect of concentration of titanium carbide (TiC) particles on the structural, mechanical, and electrochemical properties of Ni–P composite coatings was investigated. Various amounts of TiC particles (0, 0.5, 1.0, 1.5, and 2.0 g L−1) were co-electrodeposited in the Ni–P matrix under optimized conditions and then characterized by employing various techniques. The structural analysis of prepared coatings indicates uniform, compact, and nodular structured coatings without any noticeable defects. Vickers microhardness and nanoindentation results demonstrate the increase in the hardness with an increasing amount of TiC particles attaining its terminal value (593HV100) at the concentration of 1.5 g L−1. Further increase in the concentration of TiC particles results in a decrease in hardness, which can be ascribed to their accumulation in the Ni–P matrix. The electrochemical results indicate the improvement in corrosion protection efficiency of coatings with an increasing amount of TiC particles reaching to ~ 92% at 2.0 g L−1, which can be ascribed to a reduction in the active area of the Ni–P matrix by the presence of inactive ceramic particles. The favorable structural, mechanical, and corrosion protection characteristics of Ni–P–TiC composite coatings suggest their potential applications in many industrial applications

Aetiology of Diarrhoea in a Birth Cohort of Children Aged 0-2 Year(s) in Rural Mirzapur, Bangladesh

The incidence of aetiology-specific diarrhoea and the pathogenicity of infectious agents in a birth cohort (n=252) in rural Bangladesh were determined. Stool specimens or rectal swabs were collected from diarrhoeal cases over two years and routinely on a monthly basis. Stool samples from children with diarrhoea were compared with stool samples from children without diarrhoea to calculate rates of isolation and pathogenicity of agents. In total, 1,750 stool specimens from diarrhoea patients and 5,679 stool specimens from children without diarrhoea were tested. An infectious agent was identified in 58% of the stool specimens from diarrhoea patients and 21.6% of the stool specimens from children without diarrhoea. The most commonly-isolated pathogens from all specimens were enterotoxigenic Escherichia coli (ETEC), enteroadherent E. coli, Shigella , Campylobacter jejuni , Giardia , and rotavirus. ETEC (ST and LT-ST toxin), enterotoxigenic Bacteroides fragilis , Shigella, and rotavirus were associated more with disease than with asymptomatic infections. Aetiology-specific infections were associated with acute episodes. The isolated enteropathogens were essentially the same as those found in other tropical rural settings. Enterotoxigenic B. fragilis was also identified as a pathogen. Ongoing vaccine efforts focusing on Shigella, rotavirus, and ETEC would be useful

A Prospective Study of Arsenic Exposure, Arsenic Methylation Capacity, and Risk of Cardiovascular Disease in Bangladesh

Millions of persons worldwide, including 13 million Americans (U.S. Environmental Protection Agency 2009) and over 50 million in Bangladesh (British Geological Survey 2007), have been chronically exposed to arsenic, a group 1 human carcinogen (International Agency for Research on Cancer 2004), through contaminated drinking water. Arsenic exposure from drinking water has been associated with cardiovascular disease (CVD) (Chen CJ et al. 1996; Chen Y et al. 2011; Chiou et al. 1997; Liao et al. 2012; Tseng et al. 2003; Yuan et al. 2007). However, prospective studies assessing susceptibility to CVD due to arsenic exposure are rare. Arsenic in drinking water is present as inorganic arsenic (iAS). Once ingested, iAs is methylated to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The relative distribution of urinary arsenic metabolites varies from person to person and has been interpreted to reflect arsenic methylation capacity (Hopenhayn-Rich et al. 1996; Vahter 1999). Mechanistic studies have shown that MMAIII is more toxic than iAs or any of the pentavalent metabolites (Petrick et al. 2000; Styblo et al. 2000). Incomplete methylation, indicated by a high percentage of urinary MMA (MMA%), has been consistently related to cancers (Chen YC et al. 2003; Pu et al. 2007; Steinmaus et al. 2006; Yu et al. 2000), and there is some evidence of stronger associations among smokers than nonsmokers (Pu et al. 2007; Steinmaus et al. 2006). However, the association between urinary MMA% and CVD risk is unknown, and research on the combined effects of arsenic and biomarkers of arsenic susceptibility on CVD risk is needed. We conducted a prospective case–cohort study nested in a large prospective cohort to assess associations of arsenic exposure from drinking water and arsenic methylation capacity, indicated using relative distribution of urinary arsenic metabolites, with CVD risk

Safe distances between groundwater-based water wells and pit latrines at different hydrogeological conditions in the Ganges Atrai floodplains of Bangladesh

Background: Groundwater drawn from shallow tubewells in Bangladesh is often polluted by nearby pit latrines, which are commonly used toilets in rural and sub-urban areas of the country. Methods: To determine the minimum safe distance of a tubewell from a pit latrine in different hydrogeological conditions of Bangladesh, 20 monitoring wells were installed at three study sites (Manda, Mohanpur and Bagmara) with the vertical and horizontal distances ranging from 18\u201347 to 2\u201315 m, respectively. Water samples were collected three times in three seasons and tested for faecal coliforms (FC) and faecal streptococci (FS) as indicators of contamination. Soil samples were analysed for texture, bulk density and hydraulic conductivity following standard procedures. Sediment samples were collected to prepare lithological logs. Results: When the shallow aquifers at one of the three sites (Mohanpur) were overlained by 18\u201323-m-thick aquitards, the groundwater of the monitoring wells was found contaminated with a lateral and vertical distances of 2 and 31 m, respectively. However, where the aquitard was only 9 m thick, contamination was found up to lateral and vertical distances of 4.5 and 40.5 m, respectively. The soil textures of all the sites were mainly composed of loam and sandy loam. The hydraulic conductivities in the first aquifer at Manda, Mohanpur and Bagmara were 5.2\u20137.3, 8.2 and 1.4\u201315.7 m/h, respectively. Conclusions: The results showed that the safe distance from the tubewell to the pit latrine varied from site to site depending on the horizontal and vertical distances of the tubewell as well as hydrogeological conditions of a particular area

Nonmalignant Respiratory Effects of Chronic Arsenic Exposure from Drinking Water among Never-Smokers in Bangladesh

BACKGROUND: Arsenic from drinking water has been associated with malignant and nonmalignant respiratory illnesses. The association with nonmalignant respiratory illnesses has not been well established because the assessments of respiratory symptoms may be influenced by recall bias or interviewer bias because participants had visible skin lesions. OBJECTIVES: We examined the relationship of the serum level of Clara cell protein CC 16-a novel biomarker for respiratory illnesses-with well As, total urinary As, and urinary As methylation indices. METHODS: We conducted a cross-sectional study in nonsmoking individuals (n = 241) selected from a large cohort with a wide range of As exposure (0.1-761 mu g/L) from drinking water in Bangladesh. Total urinary As, urinary As metabolites, and serum CC16 were measured in urine and serum samples collected at baseline of the parent cohort study. RESULTS: We observed an inverse association between urinary As and serum CC 16 among persons with skin lesions (beta = -0. 13, p = 0.01). We also observed a positive association between secondary methylation index in urinary As and CC16 levels (beta = 0. 12,,P = 0.05) in the overall study population; the association was stronger among people without skin lesions (beta = 0. 18, p = 0.04), indicating that increased methylation capability may be protective against As-induced respiratory damage. In a subsample of study participants undergoing spirometric measures (n = 3 1), we observed inverse associations between urinary As and predictive FEV1 (forced expiratory volume measured in 1 sec) (r = -0.37; FEV1/forced vital capacity ratio and primary methylation index (r = -0.42, p = 0.01). CONCLUSIONS: The findings suggest that serum CC 16 may be a useful biomarker of epithelial lung damage in individuals with arsenical skin lesions. Also, we observed the deleterious respiratory effects of As exposure at concentrations lower than reported in earlier studies

Clinical Predictors and Outcome of Metabolic Acidosis in Under-Five Children Admitted to an Urban Hospital in Bangladesh with Diarrhea and Pneumonia

BACKGROUND: Clinical features of metabolic acidosis and pneumonia frequently overlap in young diarrheal children, resulting in differentiation from each other very difficult. However, there is no published data on the predictors of metabolic acidosis in diarrheal children also having pneumonia. Our objective was to evaluate clinical predictors of metabolic acidosis in under-five diarrheal children with radiological pneumonia, and their outcome. METHODS: We prospectively enrolled all under-five children (n = 164) admitted to the Special Care Ward (SCW) of the Dhaka Hospital of icddr, b between September and December 2007 with diarrhea and radiological pneumonia who also had their total serum carbon-dioxide estimated. We compared the clinical features and outcome of children with radiological pneumonia and diarrhea with (n = 98) and without metabolic acidosis (n = 66). RESULTS: Children with metabolic acidosis more often had higher case-fatality (16% vs. 5%, p = 0.039) compared to those without metabolic acidosis on admission. In logistic regression analysis, after adjusting for potential confounders such as age of the patient, fever on admission, and severe wasting, the independent predictors of metabolic acidosis in under-five diarrheal children having pneumonia were clinical dehydration (OR 3.57, 95% CI 1.62-7.89, p = 0.002), and low systolic blood pressure even after full rehydration (OR 1.02, 95% CI 1.01-1.04, p = 0.005). Proportions of children with cough, respiratory rate/minute, lower chest wall indrawing, nasal flaring, head nodding, grunting respiration, and cyanosis were comparable (p>0.05) among the groups. CONCLUSION AND SIGNIFICANCE: Under-five diarrheal children with radiological pneumonia having metabolic acidosis had frequent fatal outcome than those without acidosis. Clinical dehydration and persistent systolic hypotension even after adequate rehydration were independent clinical predictors of metabolic acidosis among the children. However, metabolic acidosis in young diarrheal children had no impact on the diagnostic clinical features of radiological pneumonia which underscores the importance of early initiation of appropriate antibiotics to combat morbidity and deaths in such population