Browsing by Author "Ahmed, S."

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Community randomized trial of zinc supplementation started during diarrhea reduces morbidity and mortality in Bangladeshi children[abstract]
(2001-09) Baqui, A.H.; Black, R.E.; Arifeen, S.E.; Yunus, Md.; Chakraborty, J.; Ahmed, S.; Vaughan, J.P.
Developing fixed service sites[book chapter]
(1997) Ahmed, S.; Hasan, Y.; Phillips, James F.
Domestic water use in a village in Bangladesh : I. A methodology and a preliminary analysis of use patterns during the cholera season
(1978-12) Briscoe, J.; Ahmed, S.; Chakraborty, M.
Improved Indicators of Infant Mortality for Integrated Primary Healthcare Programmes
(2000) Sack, David A.; Ahmed, S.; Razzaque, Abdur; Chakraborty, J.; Yunus, Mohammad
Persistent diarrhoea: associated infection and response to a low lactose diet
(2002) Ashraf, H.; Ahmed, S.; Fuchs, G.J.; Mahalanabis, D.
Post-Fire Residual Capacity of Reinforced Concrete Beam
(ICACE, 2021-03-16) Bhuiyan, M.H.; Ahmed, S.
Incidents of fire are in increasing trend in developing countries. Exposure to fire may lead to a decrease in load carrying capacity and stiffness of a reinforced concrete (RC) structure. The degree of damage is related to the fire intensity in terms of temperature and duration of fire. Assessment of the residual capacity of a fire-damaged RC structure is difficult since there is no direct method to identify the extent of damage in the structural member. Sustained high temperature on a RC beam surface leads to progressive heating of the inner layers of concrete. Consequently, reinforcement bars get exposed to excessive high temperature which reduces the strength of rebars. In this article, an attempt was made to determine the post-fire residual capacity of a RC beam subjected to fire using finite element (FE) model. For this, FE models of 4 (four) RC beams with different clear cover thickness and depth subjected to fire were developed. After model validation, these were used to determine the residual capacity of RC beams exposed to fire for a duration of 30 min to 4 h. Results show that exposure to fire reduces the residual capacity and stiffness of a RC beam significantly. The nature of failure of a RC beam may become brittle after exposure to fire for longer period. Effect of increased clear cover on the residual capacity of the RC beam was found insignificant. Comparing the post fire residual capacity of RC beams obtained from FE analysis and simplified method showed that simplified method may overestimate the residual capacity of RC beams when they are exposed in fire for long duration.
Upcycling prawn shells: Chitosan–carbon nanotube nanocomposites with boosted magnetic and electrical properties
(John Wiley and Sons Inc, 2024-03-22) Awal, R.,; Al-Mamun, M.; Jewena, N.; Khandaker, J.I.; Tanisa, N.Y.,; Ahmed, S.; Shahriar, F.,; Haque, M.M.
Multi-walled carbon nanotubes (MWCNTs) were successfully synthesized and functionalized by chemical vapour deposition and acid reflux methods, respectively. Chitosan (CTS) was prepared by a chemical extraction method from waste prawn shells. Various weight fractions of functionalized multi-walled carbon nanotubes (f-MWCNTs) have been used as reinforcing agent in CTS biopolymer matrix. Fourier transform infrared spectroscopy analysis was done, which confirms the presence of absorption bands of the various functional groups of chitin, CTS, and MWCNTs. Raman spectra revealed the quality of MWCNTs, the extent of their functionalization, and the quality of nanocomposites. The X-ray diffraction analysis showed the distinctive peaks for f-MWCNTs’ and also revealed the formation of CTS/f-MWCNTs nanocomposites. Transmission Electron Microscopy (TEM) analysis also exhibited that the CTS/f-MWCNTs nanoparticles have a well-defined crystalline structure. The highest coercivity and magnetization (Ms) of the CTS/5%f-MWCNTs nanocomposite are 602 Oe and 0.1202 emu/g, respectively that have been enhanced by 3.83 and 5.27 times compared to the pure CTS respectively. It showed that the conductivity is getting higher with the addition of f-MWCNTs in the CTS matrix. CTS/5% f-MWCNTs composites exhibit the highest conductivity than other composites and the conductivity of CTS/5% f-MWCNTs composite is 4.0×10−4 S/m. © 2024 The Authors. Micro & Nano Letters published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
Upcycling prawn shells: Chitosan–carbon nanotube nanocomposites with boosted magnetic and electrical properties
(John Wiley and Sons Inc, 2024-03-22) Awal, R.; Al-Mamun, M; Jewena, N.; Khandaker, J.I.; Tanisa, N.Y.; Ahmed, S.; Shahriar, F.; Haque, M.M.
Multi-walled carbon nanotubes (MWCNTs) were successfully synthesized and functionalized by chemical vapour deposition and acid reflux methods, respectively. Chitosan (CTS) was prepared by a chemical extraction method from waste prawn shells. Various weight fractions of functionalized multi-walled carbon nanotubes (f-MWCNTs) have been used as reinforcing agent in CTS biopolymer matrix. Fourier transform infrared spectroscopy analysis was done, which confirms the presence of absorption bands of the various functional groups of chitin, CTS, and MWCNTs. Raman spectra revealed the quality of MWCNTs, the extent of their functionalization, and the quality of nanocomposites. The X-ray diffraction analysis showed the distinctive peaks for f-MWCNTs’ and also revealed the formation of CTS/f-MWCNTs nanocomposites. Transmission Electron Microscopy (TEM) analysis also exhibited that the CTS/f-MWCNTs nanoparticles have a well-defined crystalline structure. The highest coercivity and magnetization (Ms) of the CTS/5%f-MWCNTs nanocomposite are 602 Oe and 0.1202 emu/g, respectively that have been enhanced by 3.83 and 5.27 times compared to the pure CTS respectively. It showed that the conductivity is getting higher with the addition of f-MWCNTs in the CTS matrix. CTS/5% f-MWCNTs composites exhibit the highest conductivity than other composites and the conductivity of CTS/5% f-MWCNTs composite is 4.0×10−4 S/m.