Graphene quantum dots (GQDs), impressive materials with enormous future potential, are reviewed from their inception, including different precursors. Considering the increasing burden of industrial and ecological bio-waste, there is an urgency to develop techniques which will convert biowaste into active moieties of interest. Amongst the various materials explored, we selectively highlight the use of potential carbon containing bioprecursors (e.g. plant-based, amino acids, carbohydrates), and industrial waste and its conversion into GQDs with negligible use of chemicals. This review focuses on the effects of different processing parameters that affect the properties of GQDs, including the surface functionalization, paradigmatic characterization, toxicity and biocompatibility issues of bioprecursor derived GQDs. This review also examines current challenges and s the ongoing exploration of potential bioprecursors for ecofriendly GQD synthesis for future applications. This review sheds further light on the electronic and optical properties of GQDs along with the effects of doping on the same. This review may aid in future design approaches and applications of GQDs in the biomedical and materials design fields.
The nanocomposite of polypyrrole (PPy) and carboxylated multi-walled carbon nanotubes (MWCNT) was synthesized by in situ chemical oxidative polymerization method using HCl as a dopant and Ammonium persulphate (APS) as an oxidant. The MWCNTs were carboxylic functionalized and were ultrasonicated to obtain uniform dispersion within the PPy matrix. Surface morphology of nanocomposites was investigated by Field Emission Scanning Electron microscopy (FE-SEM) and revealed that the functionalized MWCNTs were well embedded. X-Ray diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, Raman spectroscopy and UV-Vis spectroscopy were used to characterize the synthesized PPy-MWCNT nanocomposite. It was found that in situ polymerized PPy layer matrix was formed on carboxylated MWCNT and there was uniform dispersion of MWCNTs within the PPy matrix with significant interaction between PPy and MWCNTs. The response of the prepared PPy-MWCNT nanocomposite sensors was studied in the form of sensitivity towards Ammonia gas (NH3). The synergistic effects of the PPy-coated MWCNTs improve the gas sensing properties. Results showed that the sensitivity increased with NH3 concentration and it was also affected by the MWCNT content in PPy matrix. Furthermore, the sensor in pellet form reported here is robust, cost effective and relatively stable at room temperature.
Researchers all over the world have provided significant and effective solutions to detect malicious URLs. Still due to the ever changing nature of cyberattacks, there are many open issues. In this paper, we have provided an effective hybrid methodology with new features to deal with this problem. To evaluate our approach, we have used state-of-the-arts supervised decision tree learning classifications models. We have performed our experiments on the balanced dataset. The experimental results show that, by inclusion of new features all the decision tree learning classifiers work well on our labeled dataset, achieving 98-99% detection accuracy with very low False Positive Rate (FPR) and False Negative Rate (FNR). Also we have achieved 99.29% detection accuracy with very low FPR and FNR using majority voting technique, which is better than the wellknown anti-virus and anti-malware solutions.
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