| 1. |
- Murugan, Vishal, et al.
(författare)
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Mechanical and Postfire Structural Performances of Concrete under Elevated Temperatures
- 2023
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Ingår i: Civil Engineering Journal. - : CEJ. - 2676-6957 .- 2476-3055. ; 9:8, s. 1863-1879
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates the mechanical and postfire structural performances of concrete under elevated temperatures (200°C, 400°C, 600°C, and 800°C) after 7 and 28 days of concrete curing. The main objective of this study is to evaluate the post-fire behavior of concrete structures and how their modulus of elasticity values influence their structural parameters. Mechanical studies, namely, the compressive strength, splitting tensile strength, and flexural strength, were performed on cubes, cylinders, and prism beams under normal and elevated temperatures. Non-destructive tests, like rebound hammer and ultrasonic pulse velocity, were also conducted on concrete cubes to obtain the strength of concrete before and after heating the specimens. Microstructural studies, in particular, scanning electron microscope and energy dispersive x-ray spectroscopy, were done to analyze the changes in the chemical composition of concrete under the effect of the temperatures. The weight loss of the concrete specimens was assessed under the elevated temperatures. The results indicated that the geometric shapes of the specimens influenced the loss in the moisture content of concrete under an elevated temperature scenario. Microstructural studies revealed the changes in the chemical composition under the elevated temperatures. The results of this research can be further integrated for industrial applications.
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| 2. |
- Youngsukkasem, S., et al.
(författare)
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Biogas production by encapsulated methaneproducing bacteria
- 2012
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Ingår i: BioResources. - 1930-2126. ; 7:1, s. 56-65
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Tidskriftsartikel (refereegranskat)abstract
- Encapsulation of methane-producing bacteria was carried out with the objective of enhancing the rate of biogas production. Encapsulation with a one-step liquid-droplet-forming technique was employed for the natural membrane, resulting in spherical capsules with an average diameter and a membrane thickness of 4.3 and 0.2 mm, respectively. The capsules were made from alginate, using chitosan or Ca 2+ as counter-ions, together with the addition of carboxymethylcellulose (CMC). A Durapore® membrane (hydrophilic PVDF) with a pore size of 0.1 μm was used for synthetic encapsulating sachets having width and length dimensions 3×3 and 3×6 cm 2 for holding the bacteria. During the digesting process, the dissolved substrates penetrated through the capsule membrane, and biogas inside the capsules was able to escape by diffusion. The results indicate encapsulation to be a promising method of digestion, with a high density of anaerobic bacteria. The method holds considerable potential for further development of membranes and their applications.
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| 3. |
- Youngsukkasem, S., et al.
(författare)
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Biogas production by encased bacteria in synthetic membranes : Protective effects in toxic media and high loading rates
- 2013
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Ingår i: Environmental technology. - : Tailor & Francis. - 0959-3330 .- 1479-487X. ; 34:13-14, s. 2077-2084
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Tidskriftsartikel (refereegranskat)abstract
- A bioreactor including encased digesting bacteria for biogas production was developed, and its performance in toxic media and under high organic loading rates (OLRs) was examined and compared with traditional digestion reactors. The bacteria (3 g) were encased and sealed in 3 × 6cm 2 PVDF (polyvinylidene fluoride) membranes with a pore size of 0.1 μ m, and then several sachets were placed in the reactors. They were then examined in toxic medium containing up to 3% limonene as a model inhibitor in batch reactors, and OLRs of up to 20 g COD / L.day in semi-continuous digestions. The free and encased cells with an identical total bacterial concentration of 9 g in a medium containing 2% limonene produced at most 6.56 and 23.06 mL biogas per day, respectively. In addition, the digestion with free cells completely failed at an OLR of 7.5 g COD / L.day, while the encased cells were still fully active with a loading of 15 g COD / L.day.
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