Ferrochrome slag (FCS) possesses promising properties that promote its use as an alternative to natural aggregates in concrete production. Still, there is a concern about the effect of ...high-temperature exposure on the properties of concrete containing FCS aggregate. Therefore, due to durability and structural fire safety, it is necessary to evaluate the properties of FCS concrete after being exposed to elevated temperatures. The present study investigates the effect of FCS fine aggregate on the physical and mechanical properties of concrete at room and elevated temperatures (i.e., 200−1000 °C). Microstructural properties at high temperatures were also evaluated using SEM-EDS analysis. The results showed an improvement in the mechanical properties of concrete with FCS fine aggregate compared to conventional concrete. After being exposed to high temperatures, the concrete containing FCS fine aggregate showed less reduction in strength properties and mass than conventional concrete. Such improvements in mechanical and physical properties are achieved due to the chemical composition and surface texture of the FCS aggregate. Microstructural observation and ultrasonic pulse velocity confirmed that FCS concrete suffered less damage upon exposure to high temperatures. Furthermore, the effect of high temperatures on the strength properties of FCS concrete is consistent with the recommendations of the codes (Eurocode 2 and ACI 216.1).
Attempts to cultivate sugar beet (Beta vulgaris spp. vulgaris) in the sub-tropical saline soils are ongoing because of its excellent tolerance to salinity. However, the intrinsic adaptive physiology ...has not been discovered yet in the sub-tropical climatic conditions. In this study, we investigated morpho-physiological attributes, biochemical responses, and yield of sugar beet under a gradient of salinity in the soil–pot culture system to evaluate its adaptive mechanisms. Results exhibited that low and high salinity displayed a differential impact on growth, photosynthesis, and yield. Low to moderate salt stress (75 and 100 mM NaCl) showed no inhibition on growth and photosynthetic attributes. Accordingly, low salinity displayed simulative effect on chlorophyll and antioxidant enzymes activity which contributed to maintaining a balanced H2O2 accumulation and lipid peroxidation. Furthermore, relative water and proline content showed no alteration in low salinity. These factors contributed to improving the yield (tuber weight). On the contrary, 250 mM salinity showed a mostly inhibitory role on growth, photosynthesis, and yield. Collectively, our findings provide insights into the mild–moderate salt adaptation strategy in the soil culture test attributed to increased water content, elevation of photosynthetic pigment, better photosynthesis, and better management of oxidative stress. Therefore, cultivation of sugar beet in moderately saline-affected soils will ensure efficient utilization of lands.
This study investigates the structural behavior and shear bond strength of composite slabs composed of profiled steel deck and ultra-lightweight cementitious composite (ULCC). ULCC topping with a ...density of about 1440 kg/m3 was used to reduce the dead weight of the composite slabs. An experimental investigation was carried out to determine the shear bond characteristics between the profiled steel sheet and the ULCC. Eight composite slabs of different shear spans were tested in accordance with EN 1994-1-1:2004, in which six slabs contained ULCC and the remaining two slabs contained normal weight concrete (NWC) to serve as a benchmark for comparison. The shear bond behavior of the ULCC composite slabs was compared to that of the NWC slabs using two sets of slabs with short and long shear span lengths. The composite slabs with ULCC topping showed higher ductile behavior and load-carrying capacity than the composite slabs with NWC topping. The shear bond properties of the composite slab with ULCC were determined using the semi-empirical m−k method and the partial shear connection method (PSC) according to EN 1994-1-1:2004. For comparison purposes, the shear bond properties of NWC composite slabs were determined. ULCC was found to provide equivalent shear bond strength with profiled steel sheet compared to the conventional composite slab with NWC. Therefore, ULCC can be used effectively in composite slabs with a greater reduction in self-weight.
•The structural performance of composite slabs with profiled steel sheet and ultra-lightweight cement composite (ULCC) was investigated.•When ULCC is used instead of normal weight concrete (NWC), the weight of the composite slab can be reduced by up to 40%.•Composite slabs with ULCC have higher ductility and load-carrying capacity than composite slab with NWC.•The m-k method and the partial shear connection method were used to calculate the longitudinal shear capacity of the composite slabs.•ULCC slab has a higher longitudinal shear strength (τu) than NWC slab.
ABSTRACTThere is a growing interest in understanding and establishing forest nurseries in swamp ecosystem areas of Bangladesh. This study aims to evaluate the socio-economic and ecological ...contribution of swamp small-scale tree nurseries. The result revealed that government and non-government organizations established swamp nurseries in Bangladesh. Swamp nursery producer generates an annual average net profit of USD 4745. Small-scale swamp nursery owners benefited in multiple forms: subsistence, house construction, savings purposes, and, most importantly, expansion of their businesses. However, the ecological aspect of seedling production was not satisfactory because of the lack of facilities such as skilled labor supply, access to high-quality germplasm, technical skills, nursery facilities, etc. In the nurseries observed, only two dominant swamp tree species, locally known as Hijol (Barringtonia acutangular) and Koroch (Pongamia pinnata) seedlings were found. In most cases, those seedlings were morphologically unhealthy, and the root structure was deformed, which was identified as a major problem of reforestation programs in wetland areas. Therefore, to make the reforestation program successful and create livelihoods for the rural poor in the wetland areas, there is an urgent need to develop quality seedlings-based swamp nurseries, which are only possible through proper nursery management techniques.
Swamp forests are now at the edge of extinction in the Haor (Haor ecosystem is a type of wetland comprised of swamp forest located in the lowlands of the north-eastern part of Bangladesh which is ...characterized by a bowl or saucer shaped shallow depression) region of Bangladesh. To reverse such a trend, there is an urgent need to start a reforestation program. However, the silvics of individual species and dynamics of swamp forest stands are only marginally understood. Hence, the purpose of this study was to provide detailed information on swamp vegetation water tolerance range and to identify suitable habitat range for species that are dominant in the reforestation program. It was found that high water-tolerant species can tolerate waterlogging conditions for an average of 13 weeks, followed by 07 weeks by medium water-tolerant species and 02 weeks by low water-tolerant species. In the case of species water depth tolerance, the high water-tolerant group can tolerate an average of 4ft water followed by 2.5 ft water by medium and 1ft by low water tolerant group. Hijol (Barringtonia acutangula), Koroch (Pongamia pinnata), Pitali (Trewia nudiflora) and Borun (Crataeva magna) were the dominant species used for existing small scale reforestation programs. There are no significant differences in resistance against water flow among Hijol, Koroch, Pitali and Borun regardless of vegetation density and water depth. For future large-scale plantations, the machine learning model shows that more than 50% of Haor area is suitable for plantations by these four species. The information generated through this study can be beneficial to planners and managers to aid in developing plantation plans and the design of habitat restoration and enhancement efforts.
Designing efficient routes for a transit network is one of the main problems faced by city planners of the world. Due to the largeness and complexity of modern day road networks it is impossible to ...make a good route design manually. So, at present computer algorithms are used to design the routes. Designing routes for transit network is a multi-criteria decision making problem which has to search a large solution space to find an optimal solution. This paper presents a novel heuristic that can quickly generate good solutions. Also we propose a Stochastic Beam Search algorithm with a heuristic inspired successor operator. We conduct extensive experiments on some benchmark datasets and perform statistical tests on the results. We show that our algorithm can successfully explore the search space. Also we compare our results with previous studies and show that our algorithms produce superior results. In particular, for large datasets, the solutions generated by our heuristic in less than a second turn out to be better than solutions generated in two hours by the state of the art algorithm.
This research study investigates the flexural behavior of fiber reinforced polymer (FRP) bars after being subjected to different levels of elevated temperatures (100, 200 and 300°C). Three types of ...glass FRP bars (ribbed, sand coated, and helically wrapped) and one type of carbon FRP bars (sand coated) were used in this study. Two testing scenarios were used: a) testing specimens immediately after heating and b) keeping specimens to cool down before testing. Test results showed that as the temperature increased the flexural strength and modulus of the tested FRP bars decreased. At temperatures higher than the glass transition temperature (Tg), significant flexural strength and modulus losses were recorded. Smaller diameter bars showed better residual flexural strength and modulus than larger diameter bars. The immediately tested bars showed significant strength and modulus losses compared to bars tested after cooling. Different types of GFRP bars showed comparable results. However, the helically wrapped bars showed the highest flexural strength losses (37 and 60%) while the sand coated bars showed the lowest losses (29 and 39%) after exposure to 200 and 300℃, respectively. The carbon FRP bars showed residual flexural strengths comparable to those recorded for the GFRP bars; however, they showed lower residual flexural modulus after being subjected to 200 and 300℃.
Background: The incidence of breast abscess ranges from 0.4 to 11% of all lactating mothers. Although breast abscess is a serious common complication of mastitis with high morbidity rate, there is a ...lack of high-quality randomized trial to demonstrate the best treatments.Methods: The Study was conducted in the Department of Surgery of Universal medical college and hospital, Dhaka, Bangladesh and MH Samorita hospital and medical college. It was a randomized controlled trial to see the efficacy of primary closure following incision and drainage of lactational breast abscess over traditional open method. Total 120 population were randomly selected in group A (60 patients) and group B (60 patients) and data was collected with their signed ethical consent. The study was conducted from January 2014 to December 2019. Collected data were classified, edited, coded and entered into the computer for statistical analysis by using Statistical package for social sciences (SPSS) version 22.Results: In patients of group A, most breast abscesses healed successfully with a nicer circumareolar scar, earlier healing, lesser number of hospital visits and lower total cost as compared to patients in group B. There was early resumption of breastfeeding and better patient satisfaction seen in group A.Conclusions: Primary closure of lactational breast abscess following incision and drainage is an effective modality of treatment of lactational breast abscess and it should be the first line of treatment, especially for larger and multilocular breast abscesses while traditional incision and drainage should be reserved for abscesses with gangrenous skin changes, where primary closure is not justified.
Background: The 50% of all male infertility is idiopathic, and there is currently no recognized treatment. The effectiveness of a nonprescription nutraceutical comprising eight nutrients on sperm ...quality in males with idiopathic infertility was studied. The aim of the study was to evaluate improvement of semen quality after treatment with folic acid and zinc in subfertile men. Methods: This prospective observational study was carried out in the infertility unit, department of obstetrics and gynaecology, Bangabandhu Sheikh Mujib medical university (BSMMU), Dhaka, Bangladesh from January 2018 to June 2020. Approval from local ethics committee was obtained for this study. Results: One hundred and twenty-five male subfertile patients were included in this study. Most men, 99 (79.2%) belong to more than 30 years, followed by 26 (20.8%) less than 30 years, range was 25 to 50 years. Mean + or - SD age was 35.3 + or - 5.1 years. Rapid linear (RL) before treatment were 16.06 + or - 14.46 (mean + or - SD) and after treatment were 22.82 + or - 13.40 (mean + or - SD). Slow linear (SL) before treatment were 17.56 + or - 12.06 (mean + or - SD) and after treatment were 19.75 + or - 9.25 (mean + or - SD). Non progressive (NP) before treatment were 10.82 + or - 8.95 (mean + or - SD) and after treatment were 10.12 + or - 7.34 (mean + or - SD). Morphology of the sperm before treatment were 19.43 + or - 15.48 (mean + or - SD) and after treatment were 30.18 + or - 19.12 (mean + or - SD). Conclusions: Our research findings fully correspond to the above research results, so it can be said that treatment of subfertile men with micronutrients like folic acid and zinc sulfate causes increase of semen quality and thus plays a key role in treatment of male subfertility. Keywords: Male subfertility. Semen analysis. Sperm quality
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