| 781. |
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| 782. |
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| 783. |
- Das, Oisik, et al.
(författare)
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An all-gluten biocomposite : Comparisons with carbon black and pine char composites
- 2019
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier. - 1359-835X .- 1878-5840. ; 120, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- Three different charcoals (gluten char, pine bark char and carbon black) were used to rectify certain property disadvantages of wheat gluten plastic. Pyrolysis process of gluten was investigated by analysing the compounds released at different stages. Nanoindentation tests revealed that the gluten char had the highest hardness (ca. 0.5 GPa) and modulus (7.8 GPa) followed by pine bark char and carbon black. The addition of chars to gluten enhanced the indenter-modulus significantly. Among all the charcoals, gluten char was found to impart the best mechanical and water resistant properties. The addition of only 6 wt% gluten char to the protein caused a substantial reduction in water uptake (by 38%) and increase of indenter-modulus (by 1525%). It was shown that it is possible to obtain protein biocomposites where both the filler and the matrix are naturally sourced from the same material, in this case, yielding an all-gluten derived biocomposite.
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| 784. |
- Das, Oisik, et al.
(författare)
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An Attempt to Find a Suitable Biomass for Biochar-Based Polypropylene Biocomposites
- 2018
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Ingår i: Environmental Management. - : Springer. - 0364-152X .- 1432-1009. ; 62:2, s. 403-413
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Tidskriftsartikel (refereegranskat)abstract
- Four biomass wastes (rice husk, coffee husk, coarse wool, and landfill wood) were added with biochar and polypropylene (PP) to manufacture biocomposites. Individual biomasses were tested for their combustion behavior using cone calorimeter. Biocomposites were analyzed for their fire/thermal, mechanical, and morphological properties. Wood had the most desirable comprehensive effect on both the mechanical and fire properties of composites. In particular, wood and biochar composite exhibited the highest values of tensile/flexural properties with a relatively low peak heat release rate. In general, application of waste derived biochar and biomasses drastically reduced the susceptibility of neat PP towards fire.
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| 785. |
- Das, Oisik, et al.
(författare)
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Biochar to the rescue : Balancing the fire performance and mechanical properties of polypropylene composites
- 2017
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Ingår i: Polymer degradation and stability. - : ELSEVIER SCI LTD. - 0141-3910 .- 1873-2321. ; 144, s. 485-496
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Tidskriftsartikel (refereegranskat)abstract
- Biochar based wood/polypropylene (PP) composites were manufactured with two flame retardants (FRs): ammonium polyphosphate/APP and magnesium hydroxide/Mg(OH)(2). The amounts of wood and biochar were alternated for accommodating the FRs in each blend. Flammability and mechanical characterisation for both the batches containing different FRs were done. Having higher proportion of biochar and less wood is beneficial to reduce flammability. The thermally stable biochar contributes to formation of effective char to restrict O-2 transfer into PP. The higher weight ratio of biochar than wood in the composites compromised the tensile and flexural strengths to some extent as the APP and Mg(OH)(2) particles were trapped inside biochar pores consequently reducing the effectiveness of biochar pore infiltration by PP. In general, addition of biochar with a woody biomass (with FRs) to neat PP significantly impedes its flammability while enhancing certain mechanical properties, such as flexural strength and tensile/flexural moduli and preserving the tensile strength. (C) 2017 Elsevier Ltd. All rights reserved.
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| 786. |
- Das, O. K., et al.
(författare)
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Evolution of aluminide coating microstructure on nickel-base cast superalloy CM-247 in a single-step high-activity aluminizing process
- 1998
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Ingår i: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. ; 29:8, s. 2173-2188
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the aluminizing of a directionally cast Ni-base superalloy, namely CM-247, by a single-step process using a high-activity pack. It is observed that significant incorporation of Al into the substrate surface during aluminizing continues over a period of about 1 hour and is not restricted merely to the first few minutes, as reported in the literature. Based on the microstructural details of the coatings formed at various stages of aluminizing, it is concluded that the coating growth in the above process takes place primarily by inward Al diffusion initially, followed by an intermediate stage when the growth involves both inward Al and outward Ni diffusion. In the final stages, the outward diffusion of Ni dominates the coating formation process. The above mechanism of coating formation is different from the one that prevails in the conventional two-step high-activity coating process in that the reaction front for the formation of NiAl remains spatially stationary despite the outward diffusion of nickel during the intermediate stage. It is also shown in the present study that the content of the Al source in the pack affects the coating structure significantly. It is further demonstrated that the microstructure of the aluminide coatings depends not only on the amount of Al incorporated in the sample during aluminizing but also on the time over which the uptake of this Al takes place.
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| 787. |
- Das, Oisik, et al.
(författare)
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Naturally-occurring bromophenol to develop fire retardant gluten biopolymers
- 2020
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to impart fire retardancy in wheat gluten polymer through naturally-occurring additives such as lanosol. The fire properties of lanosol were compared with two other conventional brominated fire retardants (Tetrabromobisphenol A and Hexabromocyclododecane). Samples containing fire retardants and gluten were prepared through compression moulding process and then characterised for their fire and mechanical properties. All fire retardants enhanced the reaction-to-fire and thermal properties of gluten while generating V-0 (i.e. vertical position and self-extinguished) ratings in the UL-94 test. The presence of all the fire retardants increased the modulus of the gluten polymer but the fire retardant particles were detrimental for the tensile strength. Nevertheless, lanosol addition delayed ignition and lowered peak heat release rate of gluten by the maximum amount, thereby leading to relatively higher fire performance index (compared to the other fire retardants). Lanosol also allowed the gluten to create a dense char barrier layer during burning that impeded the transfer of heat and flammable volatiles. The fact that only 4 wt% lanosol was able to cause self-extinguishment under direct flame and reduce peak heat release rate by a significant 50% coupled with its inherent occurrence in nature, raises the question if lanosol can be a potential fire retardant in polymeric systems, although it is a bromophenol.
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| 788. |
- Das, Oisik, et al.
(författare)
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The flammability of biocomposites
- 2018
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Ingår i: Durability and Life Prediction in Biocomposites, Fibre-Reinforced Composites and Hybrid Composites. - : Elsevier BV. ; , s. 335-365
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Keeping sustainability in mind, polymer composites are usually fabricated with biobased materials instead of synthetics. However, these “biocomposites” often lack the required strength and are extremely susceptible to fire. This necessitates the application of fire-retardant treatment, which could render the composite fire resistant. This chapter gives an overview of the types of fire retardants that are generally applied, and a review of studies done to impart fire retardancy in composites. Several instruments and standards used for determining fire behaviors of composites are also described in detail. Biochar (especially made at high pyrolysis temperatures) is very resistant to ignition and thermally stable, owing to its extensive network of cross-linking between adjacent aromatic carbon sheets. Its inclusion in polymeric composites is advantageous for both fire and mechanical properties. The inherent fire-resistant and char-forming ability of wool (a natural protein fiber) has been exploited to develop composites that exhibit the highest degree of flame resistance (V0 rating in UL94 tests). Finally, wheat gluten, a by-product of the cereal industry, has shown potential regarding fire retardancy and thermal stability. Gluten's flame-resistant properties can be made even more potent by applying other additives (e.g., silica).
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| 789. |
- Das, P., et al.
(författare)
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Exotic decay of 115Cs
- 2023
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Ingår i: Physical Review C. - 2469-9985. ; 108:6
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Tidskriftsartikel (refereegranskat)abstract
- The detailed study of the β+/EC decay of the very neutron-deficient and alpha-unbound nucleus 115Cs is presented. The measurement was performed at the ISOLDE, CERN where delayed charged particles and γ rays were detected. The observed delayed γ rays are in agreement with the previously reported characteristics γ rays of 115Xe. Based on the experimental observations, the tentative ground-state spin of 115Cs is suggested to be 7/2+ or 9/2+. Furthermore, the measured decay branching ratio of delayed protons exceeds the previously reported value. Additionally, new delayed α-branching ratio and several reconstructed proton and α-unbound excited states of 115Xe are being reported for the first time. The properties of proton-unbound states at excitation energies from 3.9–7.9 MeV have been obtained by fitting the delayed proton spectrum via the Bayesian method. The measured lifetimes of these proton-unbound states are in the order of zeptoseconds.
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| 790. |
- Das, Radhika, et al.
(författare)
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Convergent and divergent evolution of genomic imprinting in the marsupial Monodelphis domestica
- 2012
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 13, s. 394-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Genomic imprinting is an epigenetic phenomenon resulting in parent-of-origin specific monoallelic gene expression. It is postulated to have evolved in placental mammals to modulate intrauterine resource allocation to the offspring. In this study, we determined the imprint status of metatherian orthologues of eutherian imprinted genes. Results: L3MBTL and HTR2A were shown to be imprinted in Monodelphis domestica (the gray short-tailed opossum). MEST expressed a monoallelic and a biallelic transcript, as in eutherians. In contrast, IMPACT, COPG2, and PLAGL1 were not imprinted in the opossum. Differentially methylated regions (DMRs) involved in regulating imprinting in eutherians were not found at any of the new imprinted loci in the opossum. Interestingly, a novel DMR was identified in intron 11 of the imprinted IGF2R gene, but this was not conserved in eutherians. The promoter regions of the imprinted genes in the opossum were enriched for the activating histone modification H3 Lysine 4 dimethylation. Conclusions: The phenomenon of genomic imprinting is conserved in Therians, but the marked difference in the number and location of imprinted genes and DMRs between metatherians and eutherians indicates that imprinting is not fully conserved between the two Therian infra-classes. The identification of a novel DMR at a non-conserved location as well as the first demonstration of histone modifications at imprinted loci in the opossum suggest that genomic imprinting may have evolved in a common ancestor of these two Therian infra-classes with subsequent divergence of regulatory mechanisms in the two lineages.
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