In cryptography, a Substitution box (S-box) is one of the basic components of a symmetric key cryptography. Generally, it transforms a number of m input bits into n output bits. In this paper, there are presented the cryptographic properties of S-boxes and it is introduced a knowledge-based schema for building S-boxes.

A simple and reproducible spectrophotometric method has been developed for the determination of valacyclovir in bulk and pharmaceutical dosage forms. The proposed method was based on the formation of chloroform extractable complex of valacyclovir with wool fast blue. The absorbance of the extractable ion pair complex is measured at the wavelength of maximum absorbance 585 nm against the reagent blank prepared under identical conditions. The proposed method was validated for its selectivity, linearity, accuracy, and precision. The method was found to be suitable for the quality control of valacyclovir in bulk drug as well as in formulation.

There are so many factors that can improve students’ academic performances and also so many factors that can lead to poor academic performance. With the results of the analysis and factors  under consideration, the following factors contribute positively to students’ academic performance: good parental background, adequate hostel facilities, good attitude to studies, adequate educational resources, good teaching methods and involvement in only one group discussion while  having many peer groups, bad attitude to studies, involvement in too much sport activities, too much  students’ enrolment, and involving in so many  group discussion bring about  reduction in students’ academic performance.

The need of precise determination of air flow pattern and temperature distribution in a room was realized by HVAC engineers to provide comfortable temperature conditions, Relative humidity and air velocities in the occupied space. Along with the thermal comfort, the indoor air quality control minimizes the spread of airborne respiratory and other infections in hospitals.

Simulation has been carried out on FLUENT code from ANSYS for different velocities of inlet air stream and different inlet air and wall temperatures i.e. for different Re and Gr. The geometry was meshed into small control volumes. Navier-Stokes equation, energy equation and k- equations in two and three dimensional rectangular Cartesian coordinates have been solved at the control volumes. The result obtained by above numerical procedure was validated by benchmark experimental result and has been found in close agreement with it.

The results of simulation of room without occupant revealed that there is drastic change in flow pattern for Gr/Re ²>=0.1, due to prominent effect of buoyancy. It is observed that that high inlet air velocities (>=2.5 m/s) are unsuitable as it causes non uniform temperature distribution and unnecessary energy utilization. The air flow pattern, temperature distribution and relative humidity contours for two dimensional flow with occupant indicate that thermal gradient due to human body temperature and body’s obstruction to flow cause significant change in flow as compared to that of an empty room. Results of  simulation of hospital general ward revealed that positioning of inlet vents as several fragmented vents along the centre of roof and outlet vent as a continuous vent along the roof on both the side edges directly above the patient bed is most suitable option, however this particular option is suitable for cooling purpose and is not prescribed when there is very less temperature difference between outside temperature and inlet air temperature i.e. Gr≈0, as for very low value of Gr contaminant is seen to be recirculating and exits the ward after very long period of time.