T. S. K. Raunija; R. K. Gautam; S.C. Sharma; A. Verma
Abstract
The main objective of the work was to rapidly prepare high density short carbon fiber reinforced randomly oriented C/C composite by coupling the processes. The C/C composite was fabricated by coupling two processes. In primary high pressure HP method, medium density C/C composite was prepared by mixing ...
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The main objective of the work was to rapidly prepare high density short carbon fiber reinforced randomly oriented C/C composite by coupling the processes. The C/C composite was fabricated by coupling two processes. In primary high pressure HP method, medium density C/C composite was prepared by mixing the exfoliated carbon fibers and PMP with distilled water; moulding of the slurry; drying of the green cake; hot-pressing of the preform and finally carbonizing the compact. In secondary low pressure ITC method, the medium density C/C composite was densified by SMP in three repeated cycles to obtain high density. The composite was characterized for microstructure, density, porosity, hardness, flexural strength, compressive strength and permeability. The results showed that the coupling of primary method with secondary method resulted in fine microstructure, high density (1.70 g/cm 3 ), excellent mechanical properties (flexural strength 77 MPa and compressive strength 161 MPa) and reduced porosity & permeability.
P. Kumar; D. Kukkar; A Deep; S.C. Sharma; L.M. Bharadwaj
Abstract
Semiconductor inorganic nanocrystals or quantum dots (QDs) are nowadays extensively used for imaging and analysis of bio-molecules owing to their superior optical properties over conventional organic fluorophores. They have excellent potential for synthesizing molecular probes against various biological ...
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Semiconductor inorganic nanocrystals or quantum dots (QDs) are nowadays extensively used for imaging and analysis of bio-molecules owing to their superior optical properties over conventional organic fluorophores. They have excellent potential for synthesizing molecular probes against various biological markers such as free antigens, cell surface markers/antigens, bacteria, viruses and tissues. Traditional synthesis protocols of the QDs generally lead to the formation of hydrophobic nanocrystals. For biological applications, post-synthesis modifications need to be introduced to render required hydrophilicity. However, such additional steps make the tiny QDs structures bulky, which is unwanted in subsequent in-vivo executions. The present work reports a simple method for the direct synthesis of hydrophilic carboxyl (–COOH) functionalized CdS QDs using mercaptopropionic acid as a sulfur source and stabilizer. This aqueous synthesis route avoids the requirement of extra surface modification steps. The size and surface morphology of the synthesized CdS QDs were studied by electron microscopy. The average diameter of the QDs has been found to be in the range of 2-3.5nm. Spectral studies confirmed the grafting of –COOH terminal on the synthesized nanocrystals. Band gap energy and the theoretical size of the particles were calculated and found in good agreement with the experimental analysis. Due to the size quantization effect, the estimated band gap energy (2.6eV) of the QDs was on a higher side than that reported (2.4eV) for the bulk material. The synthesized nanocrystals can be further conjugated with bio-molecules for high-throughput drug screening, clinical immunological assays and protein-protein interaction studies.
