Sequential asymmetric third order rotatable designs (SATORDs).

Rotatable designs that are available for process/ product optimization trials are mostly symmetric in nature. In many practical situations, response surface designs (RSDs) with mixed factor (unequal) levels are more suitable as these designs explore more regions in the design space but it is hard to get rotatable designs with a given level of asymmetry. When experimenting with unequal factor levels via asymmetric second order rotatable design (ASORDs), the lack of fit of the model may become significant which ultimately leads to the estimation of parameters based on a higher (or third) order model. Experimenting with a new third order rotatable design (TORD) in such a situation would be expensive as the responses observed from the first stage runs would be kept underutilized. In this paper, we propose a method of constructing asymmetric TORD by sequentially augmenting some additional points to the ASORDs without discarding the runs in the first stage. The proposed designs will be more economical to obtain the optimum response as the design in the first stage can be used to fit the second order model and with some additional runs, third order model can be fitted without discarding the initial design.

A novel approach for synthesis of silver nanoparticles using Pila virens shell and its mosquito larvicidal activity.

Mosquito act as a vector for variety of deadly diseases. In this study, larvicide activity was investigated in relation to Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus) of synthesised silver nanoparticles (AgNPs) of the Pila virens (P.virens) shell extract. The characterization techniques UV-vis spectral, Fourier transforms infrared spectroscopy (FTIR),High Resonance Scanning electron microscope (HR-SEM) analysis, X-ray diffraction studies (XRD), High Resonance-Transmission electron microscopy (HR-TEM) used to characterize biosynthesized AgNPs. UV-vis, absorption showed peaks of 450 nm for the biosynthesised AgNPs, SEM observed spherical shaped particles of 25.9-28.9 nm in size and the XRD pattern shows the synthesized AgNPs fcc structure. FTIR investigation shown that the esters, carboxylic acid and ether as functional groups have been intricate in the reduction of metal ions. The larvicidal efficacy of synthesized AgNPs towards a larvae of A. aegypti LC50and LC90 value of (37.87 and 132.86 ppm) and C. quinquefasciatus was (14.70 and 28.96 ppm) respectively. The synthesized AgNPs of P. virens confirmed highest mortality towards larvae of and A. aegypti and C. quinquefasciatus.