ABSTRACT
Here, straightforward and environmentally friendly fluorescent nitrogen doped carbon quantum dots (N-CQDs) with a high blue fluorescence emission at 455 nm are used for ultrasensitive Hg2+ ion detection. Folic acid and urea are used as carbon sources in the carbonization process. Two broad absorption bands at around 280 and 370 nm from UV-Vis spectrum and characteristic absorption peaks from infrared spectrum confirms the successful synthesis of the N-CQDs. Energy dispersive X-Ray analysis confirmed the elemental composition of the N-CQDs. Transmission electron microscopy showed the homogeneous globular morphology of the N-CQDs with an average particle size of 65 nm. Zeta potential measurement established the stability and surface charge of N-CQDs. Dynamic light scattering measurement showed the average size of N-CQDs. With the addition of Hg2+ ion to N-CQDs, the blue fluorescence emission is quenched. Moreover, the N-CQDs can be applied to real water sample such as pond water, river water, and tap water. The detection limit is approximately calculated to be 12 nM and linear range is 0-30 parts per billion.
ABSTRACT
Nowadays security is main issue during transmission of data. Among many cryptographic methods, ECC is the public key asymmetric cryptosystem which provides faster computation over smaller size in comparison to other asymmetric key cryptosystems. In this paper, we have proposed a group security algorithm using the ECC cryptography algorithm. The group security is applied to ECC in terms of m-gram selection called ECC m-gram selection. Due to the group security implementation in terms of common grams, processing speed will be faster in comparison to individual item security. We have also made the comparison study between the traditional ECC algorithm with the proposed group security algorithm using generalized frequent-common gram selection for depicting lesser time requirements to achieve better security for the whole process.
