Advanced Heteroatom Doped Nanocarbon Materials as Platinum Catalyst Supports for Fuel Cells

The pressing demand for high performance, operationally stable and inexpensive electrocatalyst materials for proton exchange membrane fuel cells (PEMFCs) has spurred significant research and development interest in this field. Until now, fuel cells based on commercially available Pt/C electrocatalysts have not met some of the technical challenges to the widespread commercial adoption of PEMFCs. The main issues associated with the commercial validity of PEMFCs are the high cost and inadequate long term operational stability of Pt/C catalysts typically used to facilitate the inherently sluggish oxygen reduction reaction (ORR). Therefore, the replacement of Pt/C with novel and more effective catalyst materials is critical. These expensive precious metal catalysts make up a large portion of the overall PEMFC stack cost and suffer degradation under harsh potentiodynamic conditions. Therefore, careful electrocatalyst design strategies must be developed to reduce the cost of ORR catalysts with sufficient activity and stability to meet the technical targets set for the use of PEMFCs. In this work, two approaches are applied to develop new electrocatalyst materials for PEMFCs. The first is to design unique sulfur-doped graphene (SG) and sulfur-doped CNT (S-CNT) supports with the objective of replacing the traditional carbon black to enhance stability toward carbon corrosion. The second is to deposit Pt nanoparticles and nanowires onto SG and S-CNT with the objective of exceeding the activity and stability possible with conventional catalysts. These two catalyst technologies are developed with the ultimate objective of integrating the Pt electrodes into membrane electrode assembly (MEA) to provide excellent PEMFC performance. The first study focuses on the use of SG prepared by a thermal shock/quench anneal process as a unique Pt nanoparticle support (Pt/SG). These materials are subjected to a variety of physicochemical characterizations and electrochemical investigation for the ORR. Based on half-cell electrochemical testing in acidic electrolyte, Pt/SG demonstrated increased ORR activity and unprecedented stability over the state-of-the-art commercial Pt/C, maintaining 87% of its electrochemically active surface area following accelerated durability testing. Density functional theory (DFT) calculations highlighted that the interactions between Pt and graphene are enhanced significantly by sulfur doping, leading to a tethering effect that can explain the outstanding electrochemical stability. Furthermore, sulfur dopants resulted in a downshift of the Pt d-band center, explaining the excellent ORR activity and rendering SG as a new and highly promising class of catalyst supports for electrochemical energy technology and PEMFCs. The beneficial impacts of SG support can be utilized by growing more stable nanostructures such as Pt nanowires on SG to further improve the activity and stability of Pt catalysts. Toward this end, we carried out the direct growth of platinum nanowires on SG (PtNW/SG) by a simple, surfactant free solvothermal technique. The growth mechanism, including Pt nanoparticle nucleation on SG, followed by nanoparticle attachment with orientation along the direction is also highlighted. PtNW/SG demonstrated increased Pt mass activity and a specific activity that is 188% higher than state-of-the-art commercial Pt/C catalysts. Most notably, under a harsh potentiodynamic condition (potential cycles: 3000, potential range: 0.05 to 1.5 V vs RHE), PtNW/SG retained 58% of its electrochemically active surface area and 67% of its ORR activity in comparison to Pt/C that retained less than 1% of its surface area and activity and so failed. Given the evidence that SG is a promising support for Pt catalysts, the next logical step is to investigate the influence of sulfur on catalytic materials. Accordingly, we study the effects of sulfur on the electrochemical activity and stability of various SG supported platinum nanowires (PtNW/SGs). To investigate the influence of sulfur, a series of SG materials with varying sulfur contents ranging from 0.35 to 3.95 at% are investigated as Pt nanowire catalyst supports. Based on the physico-chemical characterizations, electrochemical measurements and DFT calculations, the amount of sulfur is shown to significantly affect the electrokinetics of the Pt nanowires. The best ORR kinetics are observed for the Pt nanowires supported on graphene with 1.40 at% sulfur. At higher sulfur contents, further enhancements are not observed, and in fact, leads to a loss of activity. At lower sulfur contents, the beneficial role of sulfur does not have a marked impact on performance so that the characteristics and performance more closely resemble that obtained with undoped graphene supports. Obviously, the beneficial effect of sulfur dopant species can be utilized by doping sulfur into other types of carbon supports such as CNT (S-CNT). Finally, we report on the synthesis, characterization and electrochemical evaluation of S-CNT-supported Pt nanowires (PtNW/S-CNT). PtNW/S-CNT synthesized by a modified solvothermal method demonstrated an increased mass activity and a specific activity 570% higher than state-of-the-art Pt/C. The stability of PtNW/S-CNT is also shown to be very impressive through accelerated degradation testing. Only insignificant changes to the electrochemically active surface area (ECSA, 93% retention) and mass activity (81% retention) of PtNW/S-CNT are observed over the course of cycling, in contrast to sizable losses observed with commercial Pt/C (<1% retention in ECSA and mass activity) under same conditions

Community-based indigenous tourism, NGOs and indigenous poverty in Bangladesh

Indigenous peoples, with unique cultures and ways of life, often constitute the most vulnerable groups of society and may experience discrimination and marginalisation in many forms. Observing the growing quest to obtain first-hand experiences of indigenous cultures and lifestyles, many indigenous communities around the world have embraced tourism as a way forward for their socio-economic development, primarily to address their poverty. This is evident in the increasing focus on community-based tourism (CBT), indigenous tourism and their application together. Concomitantly, many development-oriented organisations, i.e. donors and NGOs, have incorporated tourism as an additional means of development, explicitly emphasising the inclusion of indigenous and/or host communities within the formal tourism economy. However, the outcomes of such involvement and interventions are sometimes questionable and previous studies in this regard have proved inconclusive, especially in the context of indigenous poverty alleviation in developing countries. This study thus aims to investigate the role of NGOs in alleviating rural indigenous poverty through the facilitation of community-based indigenous tourism (CBIT) involvement in a developing country context - Bangladesh. Fitting into the domain of critical theory, a qualitative case study approach was adopted where multiple methods, including semi-structured interviews, focus group discussions and observations, were employed to collect empirical evidence from two indigenous communities in Bangladesh. Following this a thematic analysis was applied in analysing the qualitative data collected and developing the key findings. Findings show that NGO-facilitated tourism involvement has created some economic opportunities (e.g. income and employment, access to credit) that are limited in amount but significant considering the marginal conditions of the communities. Such involvement was to some extent also found to be contributing to the empowerment and reduced economic vulnerability of the communities. Simultaneously, the findings show that these benefits come along with several costs (e.g. creating external dependency, invasion of indigenous privacy, the threat of displacement) that overshadow the positive gains in many cases. The study reveals a dynamic interplay of multidimensional empowerment aspects moving beyond the mere economic aspect. While investigating the research issue, the findings observed a high interdependency between opportunity, empowerment and security. The thesis also examines a range of factors that restrict the indigenous communities (e.g. tensions, seasonality, market constraints, macro-environmental effects) and NGOs (e.g. strategic limitations and activity constraints) in operationalising tourism benefits. Finally, based on the empirical evidence and considering the existence of a development gap, the study concludes that NGO-facilitated tourism involvement (both direct and indirect) can make a contribution to indigenous poverty alleviation; however, this could best be viewed as an additional tool rather than an alternative tool to their traditional livelihood practices. This thesis contributes to the broader discussion of externally-facilitated tourism involvement for indigenous communities, as well as to the debate over the tourism-indigenous poverty nexus from such involvement. In doing so, the thesis reflects a combination of theoretical, conceptual and methodological contributions with associated practical implications. It incorporates the understanding of the key elements of stakeholder identification and salience theory (power, legitimacy and urgency) along with the poverty alleviation determinants (opportunity, empowerment and security) from the anti-poverty tourism research framework. The study demonstrates the utility of this conjoined conceptual approach that provides a conceptual schema to facilitate and extend our current understanding of the NGO-tourism-indigenous poverty nexus. The thesis also adds to our current understanding of community-based tourism from a non-western research perspective, and revealing the challenges and related opportunities in the conducting of research with indigenous communities, and by non-indigenous researchers

Photocatalytic Activity: Experimental Features to Report in Heterogeneous Photocatalysis

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic light. In this regard, an astonishing number of recent research articles include claims of highly efficient (photo)catalysts or similar terms about materials with superior or enhanced efficiency for a given reaction without proper experimental support. Consequently, the comparison of the efficiencies of photocatalysts may result as being meaningless, especially when reports are only based on expressions determining (1) a reaction rate per weight of catalyst or its surface area, (2) quantum efficiencies or quantum yields, and (3) turnover frequencies or turnover numbers. Herein, we summarize the standards needed for reporting valuable data in photocatalysis and highlight some common discrepancies found in the literature. This work should inform researchers interested in reporting photocatalysis projects about the correct procedures for collecting experimental data and properly characterizing the materials by providing examples and key supporting literature

Forest-based Tourism in Bangladesh: Challenges Unveiled for the Sundarbans

Tourism is one of the ever-growing industries all around the world. It has been highlighted recently as a priority sector for Bangladesh to utilize the country’s natural beauty, cultural, and archaeological heritage. Among lots of attractions, the Sundarbans Reserved Forest (SRF) in Bangladesh is the single most extensive mangrove forest in the world. The United Nations Educational, Scientific and Cultural Organization (UNESCO) has declared the Sundarbans as a world heritage site since it represents the world’s largest continuous mangrove forest. Despite having so many advantageous factors and parameters, Sundarbans has not been able to attract the deserved level of attention and remains impoverished. This study has considered the Sundarbans as a single holistic case to understand various challenges within a lens of forest-based tourism aligning the tourism development context of Bangladesh. In so doing, a qualitative research approach has been employed. Under such an approach, multiple data collection techniques have been utilized to collect empirical evidence including in-depth interviews, participant observation, and secondary (both published and unpublished) sources. Findings of the study indicate that tourism development in Sundarbans is challenged by inadequate infrastructures, lack of proper planning and management, dominance of wealthy urban elites, lack of training and education, limited support from local authorities, issues of security, and deception from fraudulent intermediaries. This research is particularly meaningful for tourism policymakers in Bangladesh who lack research support for their decisions. Keywords: forest-based tourism, challenges, the Sundarbans, tourism policymakers, Banglades

NELL-1 positive membranous nephropathy in association with antisynthetase syndrome

Membranous nephropathy (MN) is an important cause of nephrotic syndrome and is associated with significant adverse health outcomes including progression to end-stage kidney disease, complications relating to volume overload and increased risk of venous thromboembolism. Primary MN is frequently linked to antibodies against the phospholipase A2 receptor, although a broader range of target autoantigens are emerging. We report a case of a man in his mid-60s who had been recently diagnosed with antisynthetase syndrome presenting with nephrotic syndrome. A kidney biopsy revealed findings in keeping with MN, including positive immunohistochemical staining for the neural epidermal growth factor-like 1 protein (NELL-1) autoantigen. This report highlights a possible novel association between antisynthetase syndrome and NELL-1 positive MN

Rural Development and Food Security Through Homestead Vegetable Production: A Case Study

Cumilla Sadar Dakshin region is highly diverse in respect to land types, topography, agro-ecology, land-use pattern, cropping systems and crop variability & variety. Agricultural development of the region largely depends on the reliable and comprehensive statistics of the existing cropping cultivation and its related system adopted by the farmers. To investigate the homestead vegetable production and its impact on family nutrition, food security, income generation as well as involvement of female members a survey study was conducted at Cumilla Sadar Dakshin during 2019. A total of 150 selected homesteads were surveyed for this purpose through developed questionnaire and focus group discussion. Both primary and secondary data has been collected from different sources to fulfill the objectives of the study. The results of this study indicated that the farmer’s age, marital status, education level, farm size, source of income, women participation etc. Farmer’s knowledge and farming experiences, perception and attitude differs on different demographic conditions like: age, sex, education, farm size, training which significantly influence the adoption of modern technologies provided by different organizations. The results also showed that women contribution in homestead vegetable production is high in medium farmer’s category 41.67% and low in small farmers 36.36% respectively. The highest number of total vegetables was produced by the medium farmer (63,732 kg/year) followed by small (39,445 kg/year) and marginal farmer (25,514 kg/year). This study provides some recommendation which might impacts on betterment of farmers’ occupational and socio-economic condition by establishing proper policy and legislation both in local and national level administration as well as agricultural extension

Antibiotic usage practices and its drivers in commercial chicken production in Bangladesh

Irrational and inappropriate use of antibiotics in commercial chicken production can contribute to the development of antimicrobial resistance. We aimed to assess antibiotic usage in commercial chicken production in Bangladesh, and identify factors associated with this practice. We conducted a large-scale cross-sectional study to collect information on antibiotic usage in commercial chickens from January to May 2021. Structured interviews wereconducted with 288 broiler, 288 layer and 192 Sonali (locally-produced cross-bred) farmers in 20 sub-districts across Bangladesh. The frequency of antibiotic usage, the types of antibiotics and purpose of usage were estimated for each production type. Adjusted odds ratios (aOR) were calculated to measure the association between antibiotic usage and factors related to the characteristics of the farms and farmers using multivariable logistic regression models. The proportion of farms, irrespective of their production type, reporting usage of antibiotics in the 24 hours preceding the interview was 41% (n = 314, 95% CI: 37–44%). Forty-five percent (n = 344, 41–48%) reported antibiotic usage in the last 72 hours, 86% (n = 658, 83–88%) in the last 14 days, and almost all farms, 98% (n = 753, 97–99%), had used antibiotics since the start of their production cycle. Use of antibiotics in the 24 hours preceding an interview was more frequently reported in broiler (OR 1.91, 95% CI: 1.36–2.69) andSonali (OR 1.94, 95% CI: 1.33–2.33) than layer farms. Oxytetracycline (23–31%, depending on production type), doxycycline (18–25%), ciprofloxacin (16–26%) and amoxicillin (16–44%) were the most frequently used antibiotics. Antibiotics were reported to be used forboth treatment and prophylactic purposes on most farms (57–67%). Usage of antibiotics in the 24h preceding an interview was significantly associated with the occurrence of any illnesses in chickens (aOR broiler: 41.22 [95% CI:13.63–124.62], layer: aOR 36.45[9.52– 139.43], Sonali: aOR 28.47[4.97–162.97]). Antibiotic usage was mainly advised by veterinary practitioners (45–71%, depending on production type), followed by feed dealers (21–40%) and farmers (7–13%). Improvement of chicken health through good farming practices along with changes in key stakeholders (feed dealers and practitioners) attitudes towards antibiotic recommendations to farmers, may help to reduce the levels of antibiotic usage and thus contribute to mitigate antimicrobial resistanc

Community-based indigenous tourism, NGOs and indigenous poverty in Bangladesh

Indigenous peoples, with unique cultures and ways of life, often constitute the most vulnerable groups of society and may experience discrimination and marginalisation in many forms. Observing the growing quest to obtain first-hand experiences of indigenous cultures and lifestyles, many indigenous communities around the world have embraced tourism as a way forward for their socio-economic development, primarily to address their poverty. This is evident in the increasing focus on community-based tourism (CBT), indigenous tourism and their application together. Concomitantly, many development-oriented organisations, i.e. donors and NGOs, have incorporated tourism as an additional means of development, explicitly emphasising the inclusion of indigenous and/or host communities within the formal tourism economy. However, the outcomes of such involvement and interventions are sometimes questionable and previous studies in this regard have proved inconclusive, especially in the context of indigenous poverty alleviation in developing countries. This study thus aims to investigate the role of NGOs in alleviating rural indigenous poverty through the facilitation of community-based indigenous tourism (CBIT) involvement in a developing country context - Bangladesh. Fitting into the domain of critical theory, a qualitative case study approach was adopted where multiple methods, including semi-structured interviews, focus group discussions and observations, were employed to collect empirical evidence from two indigenous communities in Bangladesh. Following this a thematic analysis was applied in analysing the qualitative data collected and developing the key findings. Findings show that NGO-facilitated tourism involvement has created some economic opportunities (e.g. income and employment, access to credit) that are limited in amount but significant considering the marginal conditions of the communities. Such involvement was to some extent also found to be contributing to the empowerment and reduced economic vulnerability of the communities. Simultaneously, the findings show that these benefits come along with several costs (e.g. creating external dependency, invasion of indigenous privacy, the threat of displacement) that overshadow the positive gains in many cases. The study reveals a dynamic interplay of multidimensional empowerment aspects moving beyond the mere economic aspect. While investigating the research issue, the findings observed a high interdependency between opportunity, empowerment and security. The thesis also examines a range of factors that restrict the indigenous communities (e.g. tensions, seasonality, market constraints, macro-environmental effects) and NGOs (e.g. strategic limitations and activity constraints) in operationalising tourism benefits. Finally, based on the empirical evidence and considering the existence of a development gap, the study concludes that NGO-facilitated tourism involvement (both direct and indirect) can make a contribution to indigenous poverty alleviation; however, this could best be viewed as an additional tool rather than an alternative tool to their traditional livelihood practices. This thesis contributes to the broader discussion of externally-facilitated tourism involvement for indigenous communities, as well as to the debate over the tourism-indigenous poverty nexus from such involvement. In doing so, the thesis reflects a combination of theoretical, conceptual and methodological contributions with associated practical implications. It incorporates the understanding of the key elements of stakeholder identification and salience theory (power, legitimacy and urgency) along with the poverty alleviation determinants (opportunity, empowerment and security) from the anti-poverty tourism research framework. The study demonstrates the utility of this conjoined conceptual approach that provides a conceptual schema to facilitate and extend our current understanding of the NGO-tourism-indigenous poverty nexus. The thesis also adds to our current understanding of community-based tourism from a non-western research perspective, and revealing the challenges and related opportunities in the conducting of research with indigenous communities, and by non-indigenous researchers

PHOTOCATALYTIC APPLICATIONS OF TiO\u3csub\u3e2\u3c/sub\u3e FOR CATECHOL DEGRADATION AND α-Fe\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e FOR CARBON DIOXIDE REDUCTION AT AIR-SOLID INTERFACE

Natural and anthropogenic processes are emitting organic and inorganic pollutants, such as phenolic compounds, carbon dioxide (CO2), etc. in the atmosphere, which are increasing with time. In addition, to meet the energy demand of world’s growing population using nonrenewable fossil fuels are causing its depletion. Therefore, development of new technologies that can minimize atmospheric pollution and contribute to energy demand is imperative. Many methods or technologies have been developed for addressing those issues so far including advanced oxidation process, anaerobic biological treatments, and photocatalytic process. Among them, heterogenous semiconductor photocatalysis possesses clean and low-cost methodology and can simultaneously solve the problems of energy and environmental contamination. In this thesis, photocatalytic catechol (model pollutant) degradation with Degussa P25, a mixture of anatase and rutile phase of titanium dioxide (TiO2) and CO2 reduction with potassium and gallium-doped iron oxide (α-Fe2O3) are reported. The research uses Degussa P25 to study the degradation of catechol at air-solid interface because of low cost, stability, and abundant sources of TiO2. Catechol forms a chelate with TiO2 and shows absorption band in visible range through ligand-to-metal charge-transfer (LMCT) transition. The photocatalytic activity of catechol degradation on TiO2 surface are reported irradiating at λcut-off ≥ 320 nm, 400 nm, and 515 nm. The generation of reactive oxygen species (hydroxyl radical, superoxide anion radical, singlet oxygen) and redox pairs has been studied with scavengers. The chemical fates of scavengers and selectivity are also reported. Finally, the apparent quantum efficiency (AQE) for catechol loss and CO2 and carbon monoxide (CO) growths are determined. The amount of CO2 in the atmosphere can be minimized by reducing it to useful fuels photocatalytically. Potassium-doped iron oxide materials of varying potassium compositions (100 Fe:x K, 0 ≤ x ≤ 5) and calcination temperatures (400 °C, 500 °C, 600 °C, 700 °C, and 800 °C) are synthesized using incipient wetness impregnation method. The structure, composition, and properties of the catalysts are investigated by X-ray diffraction, thermal analysis and multiple spectroscopies, including: DRUV-vis, FTIR, Raman, ICP-AES, XPS and UPS, TEM with EDS and SAED. UV-visible light (λcut-off ≥ 295 nm) excites the catalysts in presence of pure CO2 or air (400 ppm CO2), both under a saturated water vapor atmosphere. The AQE for the CO(g) production shows maximum for 100 Fe:1 K. The surface-doped potassium photocatalyst enhances the photocatalytic efficiency by creating a more negative conduction band than the CO2/CO reduction potential. The role of potassium and nitrate has been explored. We also synthesize gallium-doped iron oxide using precipitation method with varying gallium compositions (100 Fe:x Ga, 0 ≤ x ≤ 5). The photocatalytic experiment similar to that of potassium-doped catalysts are performed. The material, 100 Fe:2 Ga shows greater reactivity creating a great scope for future studies. The studies of pollutant degradation and CO2 reduction with TiO2 and α-Fe2O3, respectively at air-solid interface provides a pathway to minimize the atmospheric pollution and contribute to the energy. They create a path to study more for other applications in air purification, water splitting, fuel production, etc. and development of efficient semiconductor photocatalyst

Working Capital Management and Profitability: A Study on Cement Industry in Bangladesh

Working capital management is the key to success for the manufacturing firm. As a manufacturing firm the profitability of cement industry mainly depends on the efficient management of working capital e.g. managing the current assets and current liabilities satisfactorily. This study is decorated to outline the profitability and working capital position of selected cement industries, correlation between them and whether the profitability is affected by working capital management. Ratio Analysis have been used to show Profitability position &amp; Working Capital position, Correlation Matrix have been used to show correlation between them and Regression Analysis have been used to show the impact of Working Capital management on Profitability respectively. The study is mainly based on secondary data. The study reveals that Profitability position &amp; Working Capital position over the study period is not satisfactory. From the study it is also found that there is significantly positive correlation between profitability and working capital components as well as impact of day sales outstanding (DSO) on profitability ratios is negatively significant. The study recommended that sample cement industries should reduce their day sales outstanding (DSO) for improving their profitability position. Keywords: Profitability, Working capital management, Inventory conversion period, Day sales outstanding, Payable deferred period, cash conversion period, cement industry