Perovskite Color Detectors : Approaching the Efficiency Limit
Hossain, Mohammad Ismail ; Khan, Haris Ahmad ; Kozawa, Masayuki ; Qarony, Wayesh ; Salleo, Alberto ; Hardeberg, Jon Yngve ; Fujiwara, Hiroyuki ; Tsang, Yuen Hong ; Knipp, Dietmar - \ 2020
ACS Applied Materials and Interfaces 12 (2020)42. - ISSN 1944-8244 - p. 47831 - 47839.
color science - color sensor - optical detector - perovskite - quantum efficiency
Color image sensing by a smartphone or digital camera employs sensor elements with an array of color filters for capturing basic blue, green, and red color information. However, the normalized optical efficiency of such color filter-based sensor elements is limited to only one-third. Optical detectors based on perovskites are described, which can overcome this limitation. An efficient color sensor design has been proposed in this study that uses a vertically stacked arrangement of perovskite diodes. As compared to the conventional color filter-based sensors, the proposed sensor structure can potentially reach normalized optical efficiency approaching 100%. In addition, the proposed sensor design does not exhibit color aliasing or color Moiré effects, which is one of the main limitations for the filter-based sensors. Furthermore, up to our knowledge, for the first time, it could be theoretically shown that both vertically arranged sensor and conventional color filter-based sensor provide almost comparable color errors. The optical properties of the perovskite materials are determined by optical measurements in combination with an energy shift model. The optics of the stacked perovskite sensors is investigated by threedimensional finite-difference timedomain simulations. Finally, colorimetric characterization was carried out to determine the color error of the sensors.
Vertically Stacked Perovskite Detectors for Color Sensing and Color Vision
Qarony, Wayesh ; Kozawa, Masayuki ; Khan, Haris Ahmad ; Hossain, Mohammad Ismail ; Salleo, Alberto ; Tsang, Yuen Hong ; Hardeberg, Jon Yngve ; Fujiwara, Hiroyuki ; Knipp, Dietmar - \ 2020
Advanced Material Interfaces 7 (2020)17. - ISSN 2196-7350
color moiré - color sensors - optical detectors - perovskites
Optical color sensors based on perovskites are described. These sensors overcome the limits of conventional image sensors used in smartphones and digital cameras. The sensors allow for detecting the primary colors red, green, and blue without using optical filters. The color sensors consist of vertically stacked diodes using perovskite alloys. The described sensor structure is color aliasing or color moiré error free, while conventional sensors using optical filters are limited by this error. The spectral sensitivity of vertically stacked sensors is up to three times higher than the spectral sensitivity of filter-based color sensors. The optical constants of the required perovskite alloys are determined, and color sensors are electromagnetically modeled. The spectral sensitivities of the sensors are colorimetrically characterized and compared to sensors in the literature including conventional sensors using optical filters. This study, for the first time, shows that a vertically stacked three color sensor exhibits a color error equal to, or smaller than, errors of conventional sensors using optical filters. Details on the used materials, the device design, and the colorimetric analysis are provided.
Identification and characterization of genes contributing to the virulence of the major swine pathogen Streptococcus suis
Gussak, Alex ; Ferrando, M.L. ; Murray, Gemma ; Hossain, M. ; Weinert, L. ; Baarlen, P. van; Wells, J.M. - \ 2020
In: Wias Annual Conference 2020 WIAS - p. 52 - 52.
Streptococcus suis bacteria cause serious infectious diseases in piglets, associated with substantial piglet mortality and major economic losses to the pig industry. S. suis is also a zoonotic pathogen and human infections worldwide have increased significantly in the past years. Different isolates of S. suis are highly diverse in terms of genotype and serotype and asymptomatic carriage is common in pigs, hampering the development of effective control strategies. Our group is part of a European project aimed at increasing our understanding of S. suis disease mechanisms from the genomic sequences of more than 1800 S. suis strains isolated from healthy and diseased piglets from different countries including Denmark, Germany, Spain and the Netherlands. A genome-wide-association study was used to identify a set of genes that were highly enriched in the pathogenic isolates. To investigate the function of these genes in virulence, we generated KO mutants of selected genes in S. suis using a novel genome editing approach. These genetic mutants are being characterized in a variety of in vitro infection models mimicking relevant stages of infection, including organoid systems. This approach will increase our understanding of the mechanisms underlying S. suis infection and contribute towards the development of effective control strategies.
Do oyster breakwater reefs facilitate benthic and fish fauna in a dynamic subtropical environment?
Chowdhury, Mohammed Shah Nawaz ; Shahadat Hossain, M. ; Ysebaert, Tom ; Smaal, Aad C. - \ 2020
Ecological Engineering 142 (2020). - ISSN 0925-8574
Oyster breakwater reefs used for coastal protection have shown to enhance local biodiversity. Particularly, macro-invertebrate and fish assemblages can benefit directly from reefs providing structurally complex habitats and indirectly through alteration of soft-sediment environment near the reef areas. To test this hypothesis, a manipulative field experiment was carried out on an eroding intertidal flat in the southeastern coast of Bangladesh by deploying replicate units of each 20 m long oyster breakwater reefs specially designed to protect adjacent shorelines. Transient fishes and resident intertidal macro-invertebrate communities were assessed monthly for a period of 18 months. On the intertidal flat, five transects were setup for faunal and environmental data collection, three crossing the breakwater reefs and two along the control areas without reefs. Prior to the deployment of the reefs, both the macro-invertebrate and fish assemblage were not significantly different among the five transects, indicating a rather uniform distribution of species in all tidal flats. Data collected post-reef deployment revealed that oyster breakwater reefs supported a greater biomass as well as abundance of benthic macro-invertebrates on the landward mudflat behind the reefs than the mudflat of control sites. The community structure, and seasonal variation of the macrobenthic community were associated with the variations in the sediment accumulation, as influenced by the breakwater reefs. Additionally, higher abundance of transient finfish and mobile macro-invertebrates at the reef sites suggest that the faunal communities were attracted by the higher abundance of prey resources (i.e. polychaetes, small crustaceans, juvenile gastropods and bivalves) as supported by the reefs. Thus, the reef areas served as shelter, nursery, and foraging grounds for different species. Though the ecological benefits of using oyster breakwater reefs only span adjacent to the reefs, this study confirms the importance of reef structure in facilitating local coastal biodiversity in a subtropical region.
Geo data for late blight control in potato: results of retailer survey in Rangpur, Bangladesh 2018-2019
Hossain, K.J. ; Rahman, S.M.M. ; Hengsdijk, H. - \ 2019
Wageningen : Wageningen University & Research (GEOPOTATO external report 7) - 19
Ecological engineering with oysters for coastal resilience : Habitat suitability, bioenergetics, and ecosystem services
Chowdhury, Mohammed Shah Nawaz - \ 2019
Wageningen University. Promotor(en): A.C. Smaal; T. Ysebaert, co-promotor(en): S. Hossain. - Wageningen : Wageningen University - ISBN 9789463433938 - 193
Ecosystem based coastal management has gained in interest over the last decades. Development was achieved by incorporating different ecosystems services into coastal protection that can deal with threats related to climate change, such as accelerating sea level rise and increased storminess. The ecosystem-based approach not only tries to minimize anthropogenic impacts of coastal protection infrastructures on ecosystems but also aims at offering possibilities to enhance ecosystem functioning and resilience. Natural coastal ecosystems, such as biogenic reefs, dunes, beaches and tidal wetlands have potential value in protecting the coast from erosion and waves, with the benefit that these systems have some ability to self-repair and adapt in changing climate. The use of sustainable ecosystems that integrate human society with its natural environment for the beneﬁt of both is called ecological engineering. It attempts to combine engineering principles with ecological processes to reduce environmental impacts from built infrastructure. Certain key species inhabiting those coastal habitats are known as ecosystem engineers. A number of ecosystem engineers such as coral reefs, reef forming bivalves, vegetation of kelps and seagrasses, marshes and mangroves are known to play engineering roles in shallow estuarine and coastal areas.
Reef forming bivalves that occur in coastal waters can attenuate erosive wave energies, stabilize sediments and reduce marsh retreat. Oysters are commonly said to be ecosystem engineers as they form structures that influence the environment around them in ways that are beneficial to other species. There is a positive feedback of oyster reefs on the settlement of new recruits which makes the reefs self-sustaining. They provide a variety of ecologically and economically valuable goods and services. Oyster reefs serve as natural coastal buffers, absorbing wave energy directed at shorelines and reducing erosion from boat wakes, sea level rise, and storms. Given adequate recruitment and survival, oyster reefs could be self-sustaining elements of coastal protection that enhance other habitats. More than fifty studies were conducted throughout the world since 1995 to evaluate the different ecosystem services provided by oyster reefs including coastal defence. Several studies showed that created oyster reefs can reduce the coastal erosion rate in comparison to control sites with no reefs. This PhD study utilized this concept of oysters as ecosystem engineers and studied the rock oyster, Saccostrea cucullata, in a subtropical, monsoon dominated environment in Bangladesh. This particular environment imposes dynamic conditions for oysters to grow and act as ecosystem engineers. This study investigated the critical factors that determine oyster (S. cucullata) growth and development in a dynamic, monsoon dominated coastal ecosystem of Bangladesh. This study performed experiments by using oyster breakwater reefs to evaluate their eco-engineering effect on: (1) erosion control; and (2) biodiversity of benthic macroinvertebrates and fishes. It was aimed that the application of oyster breakwater reefs can be beneficial to mitigate erosion of tidal flats, promote sediment accretion and facilitate habitats for increasing saltmarsh growth and faunal abundance.
At first, the question was where oysters can settle and grow out, so the focus is on boundary conditions in terms of habitat quality (Chapter 2). To answer this, a habitat suitability index (HSI) model was developed to identify potential suitable sites around the south-eastern Bangladesh coast, where oysters can establish. Seven habitat factors were used as input variables for the HSI model: water temperature, salinity, dissolved oxygen, particulate inorganic matter (PIM), pH, Chlorophyll-a, and water flow velocity. Comprehensive field surveys were conducted at 80 locations to collect geo-spatial environmental data, which were used to determine HSI scores using habitat suitability functions. The model results clearly showed that sites from the mouth of Sangu River to the tip of Teknaf, including the offshore islands (Kutubdia and Maheshkhali), are found suitable (HSI >0.50) habitats for oysters, except a few areas near small river mouths which become dynamic with freshwater flashes during monsoon months. These areas showed relative high salinity, Chlorophyll-a, dissolved oxygen and pH. In contrast, freshwater dominated estuaries and nearby coastal areas (i.e. northern part of the study area coving Sandwip, Feni, Mirsarai, Chittagong) with high suspended sediment concentrations from river discharges were found less suitable (HSI <0.50) for oysters. Salinity, Chlorophyll-a, dissolved oxygen and pH were identified as driving factors that determine the habitat quality for oyster in Bangladesh coast. The HSI model results match the current distribution of oysters throughout the investigated area. The good correspondence with the field data enhances the reliability of the presented HSI model as an interactive and quantitative tool for planning and managing oyster resources along the south-eastern coast of Bangladesh.
Secondly, seasonal dynamics in oyster performances are analysed by measurements of the physiological performance of the oysters as a function of environmental conditions (Chapter 3 and 4). Chapter 3 provides physiological information of S. cucullata related to different ecological parameters, which were synthesized from large number of eco-physiological experiments and the outcomes were further used to estimate the DEB model parameters. It is concluded that the hydrometeorological aspects, i.e. a monsoon regime and high turbidity levels, are quite different from temperate regions and drives the physiological traits of shellfish organisms in Bangladesh coastal waters. The estimated DEB parameters for Saccostrea cucullata and their related univariate data provided opportunities (see chapter 4) to simulate the oyster growth in a monsoon dominated hydrodynamic environment. Chapter 4 utilizes the dynamic energy budget (DEB) theory, which allows to establish links between the physiology of an organism and its environment by capturing the metabolic dynamics of an individual organism through its entire life cycle. Developed DEB model was validated by simulating S. cucullata growth under varying hydro-biological conditions. The model results are compared with independent field observations on the growth (length and weight) of S. cucullata at three different sites (Sonadia, Kutubdia and Inani) located in the south-eastern coast of Bangladesh, covering a distinct environmental gradient. The sites vary spatially and temporally in environmental conditions such as salinity, total particulate matter (TPM) and Chlorophyll-a concentrations due to the monsoonal river discharges. At the three sites, field observations of oyster growth, temperature and food availability (Chlorophyll-a and Particulate Organic Matter-POM) have been carried out in the period between September 2014 - August 2017. The DEB model reproduced temporal as well as spatial variation in oyster growth as a function of the prevailing environmental conditions. Growth rates of oysters were highest (shell length: 3cm yr-1) in Sonadia Island due to better food conditions. Whereas, the growth rates were relatively low (1.94 cm yr-1) in Kutubdia and none of oysters survived in Inani during the monsoon event due to high suspended load (889 ± 101 mg l-1) and low Chlorophyll-a (1.86 ± 0.16 µg l-1) conditions. Temporal variation is largely monsoon driven: the period between November to May was the main growing season for oysters along the Bangladesh coast, while growth slowed down in the monsoon months (June-September). DEB model simulations for S. cucullata showed good fit (>8.54 score out of 10) with measured growth data under the different in situ conditions throughout the seasons. It means that the DEB model for S. cucullata demonstrated accuracy for simulating growth in its natural environment along the Bay of Bengal. Therefore, the model can be used to evaluate potential sites for oyster culture development or restoration to enhance coastal resilience.
Thirdly, in Chapters 5 and 6, it was tested if the application of oyster breakwater reefs contribute to reducing coastal erosion in the context of monsoon-dominated subtropical coast and at the same time be beneficial in facilitating other habitats (i.e. mudflat, saltmarsh) and species (macro-invertebrates, fishes). Therefore a suitable site was chosen based on model outputs and observations, namely an eroding mudflat on Kutubdia Island. Here, concrete rings with oysters overgrown for 2 years were placed as oyster breakwater reefs in the lower intertidal zone of the mudflat. The oyster breakwater reefs were tested to see whether it reduced sediment erosion, promoted mudflat stability and enhanced seaward salt marsh expansion and growth, in comparison with areas without such reefs. The results demonstrated that oyster breakwater reefs are particularly useful to reduce erosion at lower intertidal areas as the reefs successfully trapped sediments by dissipating waves. Oyster breakwater reefs modified the mudflat morphology up to 35 m distance at the lee side with accretion of 29 cm clayey sediments and erosion rate was two times lower during the monsoon period compared to control sites. By doing so, it enhanced the growth of new salt marsh vegetation and expanded their seaward edge effectively, thereby further stabilizing the unconsolidated sediments. Therefore, along the coast of Bangladesh, where oyster larval supply is abundant, the eco-engineered breakwater structures have the potential to contribute to a more sustainable shoreline protection against erosion.
Chapter 6 aims to analyze the effects of these breakwater reefs on abundance and composition of macrobenthic soft-bottom assemblages together with transient and resident mobile fauna (fish, shrimp, crabs and other macro-invertebrates) in comparison with adjacent control sites without reefs. Seasonal influences were also considered to understand whether the effects of reefs depend on seasons. This study clearly indicates that oyster breakwater reefs had a positive effect on mudflat fauna communities. It shows higher abundances and biomass of fish and macroinvertebrates relative to the adjacent control sites. Seasonal variation was obvious, but didn’t overrule the reef impact. Multivariate analyses also demonstrated that the reef sites held distinct faunal communities, which differed from the control sites. Changes in macrobenthic community composition were associated with the variations in sediment load and characteristics, which were influenced by the breakwater reefs. Oyster breakwater reefs help to stabilize find sediments locally in lee side (landward) of the reefs, which is found as key reason to observe higher rates of macrobenthic colonization. Higher abundance of transient fish and mobile macro-invertebrates in reef sites indicated that breakwater oyster reefs attract mobile species as the reefs offer food and shelter. In fact, the study suggested that three-dimensional oyster breakwater reefs not only provide the shelter functions for mobile resident fauna, but also extend the ecosystem services related to nursing, breeding and foraging for numerous transient species by augmenting different prey resources for them. Though the ecological impact of oyster breakwater reefs was limited to a local area surrounding the reefs, this study provided hands-on evidence of ecological benefits using these reef configurations in estuarine and coastal habitats.
This PhD study demonstrates that the use of the oyster breakwater reefs has multiple benefits. It can locally protect tidal flats against erosion and promote saltmarsh growth at the lee side of the reefs. These reefs act as breakwater and dissipate wave energy that accelerate the soft sediment deposition behind the structure and increase the bed level. This type of morphological changes may provide opportunities for mangrove planting. The study also showed that eco-engineered oyster reefs can support a high density of macro-benthos in reef areas, sessile macrofauna (oysters, barnacles, sea anemones etc.) on surface of reef substrates, large number of motile macro-invertebrates in reef system that attract transient nektons. The oyster breakwater reefs clearly has the potential to improve ﬁshery production by providing high quality habitat and prey to a variety of commercially and ecologically important ﬁshes, shrimps and crabs. Despite of having these benefits and opportunities, oyster breakwater reefs also have some limitations. Oysters need to settle, survive and grow at the designated place i.e. substrates in order to achieve long-term, persistent structures and self-sustainable reefs. This depends on the habitat characteristics of the site in the first place. Not all sites are equally suitable for oyster settlement survival and growth. Selection of the right site for creating oyster reefs is crucial. Therefore, we developed a HSI model that showed to be helpful in identifying potential sites (Chapter 2). The site can be further critically evaluated by a DEB model to understand seasonal dynamics in predicting oyster growth and reproduction (Chapter 4). Particularly, burial by sediment can cause significant loss of reef habitat. It can be avoided by increasing the heights of reef substrates based on the characteristics of the site. Additional constraints are the vulnerability of oysters for diseases and predation. Oyster drills (Urosalpinx spp.) and stone crabs (Myomenippe spp.) were found as meso-predators in the investigated sites, but their effects on oyster population need to be investigated.
The intertidal rock oyster, S. cucullata can be ecologically engineered by providing hard substrates to settle on, that offers a kick-start for reef formation at places where they were lost or are desirable for coastal protection. Reef formation and development is however strongly dependent on the local environmental conditions governing oyster recruitment, survival and growth dynamics. These conditions can be highly dynamic, for example during the monsoon season. S. cucullata shows abilities to adapt to these conditions by regulating their physiological activities. The study shows that the S. cucullata populations are able to sustain in many estuarine areas along the southeast coast of Bangladesh as they can cope with the monsoonal climate. This makes them suitable for the role as eco-engineers for coastal protection. The study showed that artificial substrates can be used to develop self-sustaining oyster populations that contribute to coastal protection. Furthermore, oyster breakwater reefs dissipate the wave energy that reduces the hydrodynamic pressure on the foreshore of the primary dike and thus reduce the dike maintenance cost. Integration of oyster reefs with other ecosystems can add more benefits. Even it can enhance the possibility of doing oyster culture by enhancing larval supply in the area. Moreover, coexisting with other ecosystems viz., salt marsh and mangrove along with oyster breakwater reefs in the intertidal zone can act as bio-shield to prevent erosion and reduce the effect of cyclonic storm surges in the region. Therefore, oysters provide a great chance for Bangladesh to utilize them for the benefit of coastal people and environment.
Oyster breakwater reefs promote adjacent mudflat stability and salt marsh growth in a monsoon dominated subtropical coast
Chowdhury, Mohammed Shah Nawaz ; Walles, Brenda ; Sharifuzzaman, Sm ; Shahadat Hossain, M. ; Ysebaert, Tom ; Smaal, Aad C. - \ 2019
Scientific Reports 9 (2019)1. - ISSN 2045-2322
Oyster reefs have the potential as eco-engineers to improve coastal protection. A field experiment was undertaken to assess the benefit of oyster breakwater reefs to mitigate shoreline erosion in a monsoon-dominated subtropical system. Three breakwater reefs with recruited oysters were deployed on an eroding intertidal mudflat at Kutubdia Island, the southeast Bangladesh coast. Data were collected on wave dissipation by the reef structures, changes in shoreline profile, erosion-accretion patterns, and lateral saltmarsh movement and related growth. This was done over four seasons, including the rainy monsoon period. The observed wave heights in the study area ranged 0.1–0.5 m. The reefs were able to dissipate wave energy and act as breakwaters for tidal water levels between 0.5–1.0 m. Waves were totally blocked by the vertical relief of the reefs at water levels <0.5 m. On the lee side of the reefs, there was accretion of 29 cm clayey sediments with erosion reduction of 54% as compared to control sites. The changes caused by the deployed reefs also facilitated seaward expansion of the salt marsh. This study showed that breakwater oyster reefs can reduce erosion, trap suspended sediment, and support seaward saltmarsh expansion demonstrating the potential as a nature-based solution for protecting the subtropical coastlines.
A verified habitat suitability model for the intertidal rock oyster, Saccostrea cucullata
Chowdhury, Mohammed Shah Nawaz ; Wijsman, J.W.M. ; Hossain, M.S. ; Ysebaert, T. ; Smaal, A.C. - \ 2019
PLoS ONE 14 (2019)6. - ISSN 1932-6203
There is growing interest to restore oyster populations and develop oyster reefs for their role in ecosystem health and delivery of ecosystem services. Successful and sustainable oyster restoration efforts largely depend on the availability and selection of suitable sites that can support long-term growth and survival of oysters. Hence, in the present study a habitat suitability index (HSI) model was developed for the intertidal rock oyster (Saccostrea cucullata), with special attention: (1) to the role of the monsoon in the suitability of oyster habitats, and (2) to identify potential suitable sites along the south-eastern Bangladesh coast. Seven habitat factors were used as input variables for the HSI model: (1) water temperature; (2) salinity; (3) dissolved oxygen; (4) particulate inorganic matter (PIM); (5) pH; (6) Chlorophyll-a; and (7) water flow velocity. Seven field surveys were conducted at 80 locations to collect geospatial environmental data, which were then used to determine HSI scores using habitat suitability functions. The model results showed that the areas suitable (HSI >0.50) for oyster settlement and growth were characterized by relatively high salinities, Chlorophyll-a, dissolved oxygen and pH values. In contrast, freshwater dominated estuaries and nearby coastal areas with high suspended sediment were found less suitable (HSI <0.50) for oysters. HSI model results were validated with observed oyster distribution data. There was strong correlation between the HSI calculated by the model and observed oyster densities (r = 0.87; n = 53), shell height (r = 0.95; n = 53) and their condition index (r = 0.98; n = 53). The good correspondence with field data enhances the applicability of the HSI model as a quantitative tool for evaluating the quality of a site for oyster restoration and culture.
Growth potential of rock oyster (Sacosstrea cucullata) exposed to dynamic environmental conditions simulated by a Dynamic Energy Budget model
Chowdhury, Mohammed Shah Nawaz ; Wijsman, Johannes W.M. ; Shahadat Hossain, M. ; Ysebaert, Tom ; Smaal, Aad C. - \ 2019
Journal of Sea Research 147 (2019). - ISSN 1385-1101 - p. 19 - 27.
DEB model - Food - Monsoon - Saccostrea cucullata - Spatial and temporal variation
A Dynamic Energy Budget (DEB) model for the intertidal rock oyster (Saccostrea cucullata) is presented and applied for three different sites (Sonadia, Kutubdia and Inani) located in the south-eastern coast of Bangladesh, covering a distinct environmental gradient. At the three sites, field observations of oyster growth, temperature, total particulate matter (TPM) and food availability (Chlorophyll-a and Particulate Organic Matter-POM) were carried out during a period from September 2014 to August 2017. DEB model simulations produced temporal, as well as spatial variation in oyster growth as a function of the prevailing environmental conditions. Growth rates of oysters were highest (shell increment: 3 cm yr) at Sonadia Island due to the high food concentrations. Growth rates were relatively low (shell increment: 1.94 cm yr−1) at Kutubdia and none of oysters survived in Inani during the monsoon period. At this site TPM concentrations were quite high (889 ± 101 mg l−1), but Chlorophyll-a was quite low (1.86 ± 0.16 μg l −1) during monsoon period. Temporal variation is largely monsoon driven. The period between November to May was the main growing season for oysters along the Bangladesh coast. In contrast, growth slowed down significantly during the monsoon months (June–September). DEB model simulations for S. cucullata showed good fit (Goodness of fit score > 8.54 out of 10 and low mean relative error, MRE <0.18) with observed growth data for all three locations throughout the seasons. Therefore, the model can be used to evaluate potential sites for oyster development either for aquaculture, restoration or coastal protection to enhance coastal resilience.
Optimized rotation of an optically trapped particle for micro mixing
Hosseinzadeh, Mahmoud ; Hajizadeh, Faegheh ; Habibi, Mehdi ; Milani Moghaddam, Hossain ; Reihani, S.N.S. - \ 2018
Applied physics letters 113 (2018)22. - ISSN 0003-6951
The angular momentum transferred by circularly polarized photons is able to rotate an optically trapped microparticle. Here, the optically rotating particle is introduced as an active micromixer to reduce the mixing time in a microfluidic system. To optimize the system for microfluidic application, the effect of several optical parameters such as spherical aberration and the numerical aperture of the objective on the rotation rate of a trapped particle is investigated. The results show that the optimized depth for the rotation of a particle is located close to the coverslip and can be changed by a fine adjustment of the refractive index of the immersion oil. By applying the obtained optimized optical parameters on a trapped particle at the interface of two fluids in a microchannel, the mixing length is reduced by a factor of ∼2.
Adaptation pathways to cope with salinization in south-west coastal region of Bangladesh
Hossain, Peerzadi Rumana ; Ludwig, Fulco ; Leemans, Rik - \ 2018
Ecology and Society 23 (2018)3. - ISSN 1708-3087
Adaptation pathway - Coastal systems - Salinization
Salinization in coastal regions of Bangladesh challenges sustainable development of different sectors like agriculture, forestry, fisheries, livestock, and health. Particularly its southwest region largely faces increased salinity risks because of its geographical location and environmental settings. This study analyzes the causes of salinity increase, their cascading impacts on different coastal systems, and their livelihood implications, and assesses potential coping measures through innovative adaptation pathways for the most affected coastal systems. These pathways integrate bottom-up and top-down perceptions in adaptation planning through a driver-pressure-state-impact-response framework, multicriteria analysis, and adaptation turning point approaches. We surveyed 200 households and interviewed 20 key informants. We observed that household-level respondents’ perceptions are more closely related to socioeconomic aspects than to the biophysical environmental aspects and focus on issue-based action. However, the key informants focus more on the biophysical changes and the large-scale measures. The developed framework shows that salinity increase is an interconnected process of climatic-social-ecological-economic systems in the coastal environment. It also shows that responses already taken, i.e., polders and shrimp farming, to cope with salinization have later become pressures, i.e., riverbed siltation, waterlogging, and intensive salinization, on the systems. In total, we identified six interconnected causes of salinity increase and 24 potential measures to address them. Also we distinguished three coastal systems, i.e., crop-agriculture, drinking water sources, and the Sundarbans mangrove, most affected by salinity increase. Finally we proposed 16 adaptation pathways for these coastal systems based on the multicriteria analysis and adaptation turning points of the potential measures.
DEB parameter estimation for Saccostrea cucullata (Born), an intertidal rock oyster in the Northern Bay of Bengal
Chowdhury, Shah ; Wijsman, J.W.M. ; Hossain, M.S. ; Ysebaert, T. ; Smaal, A.C. - \ 2018
Journal of Sea Research 142 (2018). - ISSN 1385-1101 - p. 180 - 190.
DEB model - saccostrea-cuccullata - Parameter estimation - monsoon
Dynamic Energy Budget (DEB) models describe the energy flow in organisms focusing on food assimilation and utilization for maintenance, growth and reproduction. In this paper, specific DEB parameters were obtained for
the intertidal rock oyster Saccostrea cucullata, which has culture potential and important ecological functions in estuarine and coastal ecosystems along the Bay of Bengal, Bangladesh. Oyster samples were collected from natural oyster beds and used in a starvation experiment for 20 weeks in the laboratory. A sub-sample of starved oyster was used to record respiration rates and depletion of reserves was recorded by fortnightly measurements of flesh weight. Simultaneously, a group of oysters was used for physiological experiments and growth measurements, required for DEB parameter estimation. Consequently, Arrhenius temperature related parameters (i.e. TA, TL, TH, TAL, and TAH), shape coefficient (δM), volume specific maintenance rate ([PM]) and volume specific cost for structure ([EG]) were estimated using data from the respiration and starvation experiments. An iterative co-variation method was used to estimate the specific DEB parameters using the results of the physiological experiments, field observations and additional literature information. Estimated Arrhenius temperature was 5640 K, which applies between 297 and 305 K. Shape coefficient (δM=0.159) was low, compared to other oyster species that characterized the morphology of the oyster. Volume specific maintenance rate ([PM]) was equivalent to 17.99 J cm−3 day−1, while 2377 J cm−3 was estimated as the volume specific cost for structure ([EG]). These efforts provide opportunities to apply the DEB model for better understanding the energetics
of bivalves under sub-tropical conditions. It is concluded that the hydrometeorological aspects, i.e. a monsoon regime and high turbidity levels, are quite different from temperate regions and drives the physiological traits of shellfish organisms.
Elements of fishing community resilience to climate change in the coastal zone of Bangladesh
Sharifuzzaman, S.M. ; Hossain, M.S. ; Chowdhury, Sayedur Rahman ; Sarker, Subrata ; Chowdhury, M.S.N. ; Chowdhury, M.Z.R. - \ 2018
Journal of Coastal Conservation 22 (2018)6. - ISSN 1400-0350 - p. 1167 - 1176.
Analytic hierarchy process (AHP) - Fishing community - Hatiya Island - Livelihood assets - Resilience
Resilience has been conceptualized in various ways by anthropologists, ecologists, systems scientists and engineers; the boundaries of resilience are subjective and context dependent. Consequently, choosing the standards and metrics for assessing resilience remains key challenges for policy makers. In this study, using multicriteria evaluation of 40 basic criteria of human, physical, financial, natural and social assets, we have identified several elements, such as experienced fishermen, natural abundance of hilsa (Tenualosa ilisha), ability to assert decision on fish selling, nets and boats ownership, social harmony and capacity of buying food as essential livelihood assets for the fishermen at Hatiya Island, Bangladesh. These assets may enhance the relative resilience of the fishing community of the island to climate change by as much as 20–40%. The results of this study will improve our understanding of the elements that lead to resilience at the community level.
Impacts of climate change on coastal ecosystems of Bangladesh
Hossain, Peerzadi Rumana - \ 2018
Wageningen University. Promotor(en): R. Leemans, co-promotor(en): F. Ludwig. - Wageningen : Wageningen University - ISBN 9789463437653 - 152
The Sundarbans mangrove ecosystems of Bangladesh’s south-west coastal region are extremely vulnerable to climate change and its impacts particularly salinity increase. Hence. the main aim of this study is to evaluate the impacts of salinity increase on the Sundarbans mangrove ecosystems at different scales (i.e., mangrove vegetation and Royal Bengal Tiger habitat) and on the adjacent coastal communities for identifying target oriented measures to adapt to salinization. To achieve this aim, we have used a multidisciplinary research framework where both qualitative and quantitative approaches are combined. The study reveals that global climate change, regional hydrological modifications and local socio-economic shifts are the major processes associated with rapid salinization across the south-west coastal region of Bangladesh. Salinity increase and its range of processes are not only contributing to reduce world’s largest and last remaining tract of mangrove’s (i.e., Sundarbans) biodiversity, but also degrade quality tiger-habitat requirements (through, for example, availability of fresh drinking water, sufficient prey population and diverse vegetative cover). Furthermore, intensification in salinity across the south-west coast of Bangladesh has become an extensive threat for human health and livelihoods. Further changes in salinity and its range of processes will make future efforts to protect and manage these diverse ecosystems more intricate. Therefore, target oriented adaptation pathways have been developed to cope with and to enhance resilience to salinization. Thus the study provides novel insights for effective and target oriented large-scale adaptation planning in the studied region.
Can Bangladesh produce enough cereals to meet future demand?
Timsina, J. ; Wolf, J. ; Guilpart, N. ; Bussel, L.G.J. van; Grassini, P. ; Wart, J. van; Hossain, A. ; Rashid, H. ; Islam, S. ; Ittersum, M.K. van - \ 2018
Agricultural Systems 163 (2018). - ISSN 0308-521X - p. 36 - 44.
Cropland area - Food security - Land use change scenarios - Self-sufficiency ratio - Yield gap - Yield potential
Bangladesh faces huge challenges in achieving food security due to its high population, diet changes, and limited room for expanding cropland and cropping intensity. The objective of this study is to assess the degree to which Bangladesh can be self-sufficient in terms of domestic maize, rice and wheat production by the years 2030 and 2050 by closing the existing gap (Yg) between yield potential (Yp) and actual farm yield (Ya), accounting for possible changes in cropland area. Yield potential and yield gaps were calculated for the three crops using well-validated crop models and site-specific weather, management and soil data, and upscaled to the whole country. We assessed potential grain production in the years 2030 and 2050 for six land use change scenarios (general decrease in arable land; declining ground water tables in the north; cropping of fallow areas in the south; effect of sea level rise; increased cropping intensity; and larger share of cash crops) and three levels of Yg closure (1: no yield increase; 2: Yg closure at a level equivalent to 50% (50% Yg closure); 3: Yg closure to a level of 85% of Yp (irrigated crops) and 80% of water-limited yield potential or Yw (rainfed crops) (full Yg closure)). In addition, changes in demand with low and high population growth rates, and substitution of rice by maize in future diets were also examined. Total aggregated demand of the three cereals (in milled rice equivalents) in 2030 and 2050, based on the UN median population variant, is projected to be 21 and 24% higher than in 2010. Current Yg represent 50% (irrigated rice), 48-63% (rainfed rice), 49% (irrigated wheat), 40% (rainfed wheat), 46% (irrigated maize), and 44% (rainfed maize) of their Yp or Yw. With 50% Yg closure and for various land use changes, self-sufficiency ratio will be >. 1 for rice in 2030 and about one in 2050 but well below one for maize and wheat in both 2030 and 2050. With full Yg closure, self-sufficiency ratios will be well above one for rice and all three cereals jointly but below one for maize and wheat for all scenarios, except for the scenario with drastic decrease in boro rice area to allow for area expansion for cash crops. Full Yg closure of all cereals is needed to compensate for area decreases and demand increases, and then even some maize and large amounts of wheat imports will be required to satisfy demand in future. The results of this analysis have important implications for Bangladesh and other countries with high population growth rate, shrinking arable land due to rapid urbanization, and highly vulnerable to climate change.
Preliminary assessment of business model concepts alternatives : Deliverable D12.2
Heidemann Lassen, Astrid ; Meldgaard, Jens Peder ; Hossain, Mokter ; Zimmermann, K.L. ; Veer, P. van 't; Finglas, Paul M. - \ 2017
EU - 5 p.
Use of an Individual-based Model to Control Transmission Pathways of Mycobacterium avium Subsp. paratuberculosis Infection in Cattle Herds
Mamun Hossain, Shaikh Abdullah Al; Smith, R.L. ; Schukken, Y.H. ; Gröhn, Y.T. - \ 2017
Scientific Reports 7 (2017). - ISSN 2045-2322 - 14 p.
Johne's disease (JD) is a chronic enteric disease in cattle caused by Mycobacterium avian subsp. paratuberculosis (MAP). Eradicating JD is a difficult task due to the long incubation period of MAP, inefficient diagnostic tests, and delayed clinical signs. Effective control strategies can help farmers to reduce prevalence, but those most acceptable to farmers combine specific information about lactation performance and testing results, which existing models do not provide. This paper presents an individual-based model of MAP infection dynamics and assesses the relative performance of the applied alternative control strategies. The base dairy herd model included the daily life events of a dairy cow and reflects several current dairy management processes. We then integrated MAP infection dynamics into the model. The model adopted four different test-based control strategies based on risk-based culling decisions and three hygiene scenarios. The model tracked the source of each infection and quantified the efficacy of each control strategy in reducing the risks of different transmission routes. The results suggest that risk-based culling can reduce prevalence compared with no control, but cannot eliminate the infection. Overall, this work provides not only a valuable tool to investigate MAP transmission dynamics but also offers adaptability to model similar infectious diseases.
First Record of Porpita porpita (Cnidaria: Hydrozoa) from the coral reef ecosystem, Bangladesh
Shah Nawaz Chowdhury, M. ; Sharifuzzaman, S.M. ; Chowdhury, Sayedur Rahman ; Rashed-Un-Nabi, Md ; Hossain, M.S. - \ 2016
Ocean Science Journal 51 (2016)2. - ISSN 1738-5261 - p. 293 - 297.
Bangladesh - Bay of Bengal - Hydrozoa - Porpita - Saint Martin’s Island
The occurrence of Porpita porpita is reported, for the first time, in the coral island of St. Martin’s located in the southeastern coastal region of Bangladesh. P. porpita was found to occur in the lower littoral zone and beach rock pools, together with molluscan species, and collected during the pre-monsoon season when both water temperature (> 30°C) and salinity (> 30‰) tend to reach a maximum. This study recounts some details on the discovery and description of the species, and thus extends the global distribution and range limits of the genus Porpita.
Delta Atelier : Hot spot Barind
Rooij, L.L. de; Goosen, H. ; Oliemans, W.J. ; Ruhul Alam, Mollah ; Rahman, Atiqur ; Rahman, Minhazur ; Boer, Michael de; Veerbeek, William ; Slager, Kymo ; Golam Shokat, Mirja ; Abdur Rashid, Mohammad ; Hossain Choudhury, Akram ; Hossain Sourav, Sharif ; Ahmed Mohiuddin, Faruq - \ 2015
Bangladesh Deltaplan 2100 - 81 p.
Eco-engineered coastal defense integrated with sustainable aquatic food production in Bangladesh (ECOBAS)
Tangelder, M. ; Ysebaert, T. ; Chowdhury, Shah ; Reinhard, A.J. ; Doorn, F. ; Hossain, M. ; Smaal, A.C. - \ 2015
IMARES (Report / IMARES C048/15) - 39
coastal areas - coastal management - food production - bangladesh - kustgebieden - kustbeheer - voedselproductie - bangladesh
The objective of the ECOBAS project is to provide the coastal people of Bangladesh with an alternative approach for adaptation to coastal erosion and flooding. By using the concept of “eco-engineering” the natural resistance of shellfish reefs against hydrodynamic forces reduces human vulnerability to coastal erosion and flooding, and delivers a source of aquatic food. ECOBAS stands for ECO-engineered Coastal Defence Integrated with Sustainable Aquatic Food Production in BAngladeSh, and was executed by a multidisciplinary team of Dutch and Bangladesh research institutes. This report summarizes the outcomes of this study. It is not an in-depth report where scientific outcomes are discussed, but a summary for the funding agencies. The ECOBAS project was funded by Partners for Water. Also the Embassy of the Kingdom of the Netherlands financed extra monitoring activities in the second phase of the project which enabled generation of more data and a broader understanding of the research.