| 1. |
- Vivek, S.S., et al.
(författare)
-
Impact and Durability Properties of Alccofine-Based Hybrid Fibre-Reinforced Self-Compacting Concrete
- 2023
-
Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 19
-
Tidskriftsartikel (refereegranskat)abstract
- Many research works have already been made and are still in progress on metallic fibres, as their incorporation reduces the brittleness of the concrete and improves its resistance to the impact and crack propagation. But the use of such non-metallic fibres may induce corrosion which is a major problem to be addressed from the durability aspect. To overcome this problem, in the present research work, a non-metallic hybrid fibre combination was investigated with synthetic fibres like polypropylene and abaca fibres. Also, rather than using conventional cementitious materials such as silica fume, fly ash, and ground granulated blast furnace slag, a new generation of ultra-fine material namely alccofine was used as a partial replacement for the cement by 15%. Abaca fibre was utilised in a constant addition of 0.5% and blended with polypropylene fibre in a range varying from 0% to 2% with an increment of 0.5%. The fresh properties of self-compacting concrete (SCC) in mono and hybrid fibres combinations were assessed through slump flow, J-ring, and V-funnel tests. Water absorption and sorptivity tests were conducted to ensure the durability of the prepared mix. Further, impact tests were carried out on the prepared cylinder specimens to check the capability of the mix with the non-metallic hybrid combination. The main objective here was to check whether a high-strength durable SCC could be achieved using non-metallic fibres and natural fibres. From the obtained experimental results, it was observed that 15% alccofine as a partial substitute to the cement with the addition of 0.5% of abaca fibre and 2% of polypropylene fibre to SCC performed better than the control SCC.
|
|
| 2. |
-
5-HT1A targeting PARCEST agent DO3AM-MPP with potential for receptor imaging : Synthesis, physico-chemical and MR studies
- 2021
-
Ingår i: Bioorganic chemistry. - : Elsevier. - 0045-2068. ; 106
-
Tidskriftsartikel (refereegranskat)abstract
- Contrast enhancement in MRI using magnetization or saturation transfer techniques promises better sensitivity, and faster acquisition compared to T-1 or T-2 contrast. This work reports the synthesis and evaluation of 5-HT1A targeted PARACEST MRI contrast agent using 1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide (DO3AM) as the bifunctional chelator, and 5-HT1A-antagonist methoxyphenyl piperazine (MPP) as a targeting unit. The multistep synthesis led to the MPP conjugated DO3AM with 60% yield. CEST-related physicochemical parameters were evaluated after loading DO3AM-MPP with paramagnetic MRI active lanthanides: Gadolinium (Gd-DO3AM-MPP) and Europium (Eu-DO3AM-MPP). Luminescence lifetime measurements with Eu-DO3AM-MPP and computational DFT studies using Gd-DO3AM-MPP revealed the coordination of one water molecule (q = 1.43) with metal-water distance (r(M)-H2O) of 2.7 angstrom and water residence time (tau(m)) of 0.23 ms. The dissociation constant of K-d 62 +/- 0.02 pM as evaluated from fluorescence quenching of 5-HT1A (protein) and docking score of -4.81 in theoretical evaluation reflect the binding potential of the complex Gd-DO3AM-MPP with the receptor 5-HT1A. Insights of the docked pose reflect the importance of NH2 (amide) and aromatic ring in Gd-DO3AM-MPP while interacting with Ser 374 and Phe 370 in the antagonist binding pocket of 5-HT1A. Gd-DO3AM-MPP shows longitudinal relaxivity 5.85 mM(-1)s(-1) with a water residence lifetime of 0.93 ms in hippocampal homogenate containing 5-HT1A. The potentiometric titration of DO3AM-MPP showed strong selectivity for Gd3+ over physiological metal ions such as Zn2+ and Cu2+. The in vitro and in vivo studies confirmed the minimal cytotoxicity and presential binding of Gd-DO3AM-MPP with 5-HT1A receptor in the hippocampus region of the mice. Summarizing, the complex Gd-DO3AM-MPP can have a potential for CEST imaging of 5-HT1A receptors.
|
|
| 3. |
- Samson, P. Edwin, et al.
(författare)
-
The effect of fiber orientation and stacking sequence on carbon/Kevlar/epoxy intraply hybrid composites under dynamic loading conditions
- 2023
-
Ingår i: Polymers for Advanced Technologies. - : John Wiley and Sons Ltd. - 1042-7147 .- 1099-1581. ; 34:5, s. 1585-1598
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigated the thermo-mechanical behavior of (carbon/Kevlar) intraply hybrid composites. The carbon/Kevlar plies' orientation and sequential arrangement were varied. Carbon and Kevlar composites, as well as five different intraply hybrids (HFRPs) composite such as carbon-0°/Kevlar-90°, carbon-45°/Kevlar-135°, carbon-90°/Kevlar-0°, carbon/Kevlar (inter-changing layer), and carbon/Kevlar-45° (inter-changing layer) composites, and a plain epoxy panel, have been developed. The thermo-mechanical characteristics of the fabricated composites were estimated using a dynamic automated analyzer under changing mechanical and thermal load conditions. The DMA technique measured the HFRPs composite visco-elastic parameters by increasing the temperature from 30°C to 150°C at frequencies ranging from 1 to 20 Hz. Flexural test characteristics for neat epoxy, carbon fiber-reinforced composites, Kevlar fiber-reinforced composites, and carbon/Kevlar fiber-reinforced composites were estimated to aid the study. The experimentally measured versus analytically calculated viscoelastic parameters were related. The results revealed that carbon-90° oriented in warp direction/Kevlar-0° oriented in weft direction exhibited higher modulus and lower loss tangent followed by carbon/Kevlar plies oriented in alternate layers and carbon/Kevlar plies oriented in inter-changing layers at 45°. Carbon-0° introduced in the weft direction/ Kevlar-90° introduced in the warp direction, and carbon-45°/Kevlar-135° exhibited intermediate storage and loss modulus and a moderate loss tangent at the various frequency levels considered in the study.
|
|
