Effects of quenching on the morphology and crystal structure of ZnO nanostructures

Zinc oxide nanostructures were prepared by a simple wet chemical procedure using zinc acetate and sodium hydroxide as precursors. The process was subjected to quenching treatment and the effect of the treatment on the formation of the nanostructures was studied using atomic force and scanning electron microscopies. The change in crystal structure of the nanostructures due to quenching was studied using an X-ray diffractometry that established that physical and structural properties of the nanostructures were largely influenced by the quenching treatment.     

Assessment of Factors Influencing the Agrobacterium-mediated in planta Seed Transformation of Brinjal (Solanum melongena L.)

An efficient and reproducible in planta transformation method was developed for brinjal using seed as an explant. The brinjal seeds were infected with Agrobacterium tumefaciens EHA 105 harbouring pCAMBIA 1301-bar plasmid, and the transformants were selected against BASTA®. Several parameters influencing the in planta seed transformation such as pre-culture duration, acetosyringone concentration, surfactants, duration of sonication, vacuum pressure and vacuum duration have been evaluated. The putatively transformed (T ₀) brinjal plants were screened by GUS histochemical analysis. Among the different combinations and concentrations tested, when the 18-h pre-cultured brinjal seeds were sonicated for 20 min and vacuum infiltered for 3 min at 500 mm of Hg in Agrobacterium suspension containing 100 μM acetosyringone, 0.2 % Silwett L-77 favoured the Agrobacterium infection and showed maximum transformation efficiency. Among the five brinjal varieties evaluated, Arka Samhitha showed maximum transformation efficiency at 45.66 %. The transgene was successfully transmitted to progeny plants (T ₁) which was evidenced by GUS histochemical analysis, polymerase chain reaction and Southern hybridisation. The in planta protocol developed in the present study would be beneficial to transfer the economically and nutritionally important genes into different varieties of brinjal, and the transgenic brinjal plants can be produced in less time (approximately 27 days).     

Direct measurement of local instantaneous laminar burning velocity by a new PIV algorithm

This paper presents a new experimental approach using PIV technique to measure the local instantaneous laminar burning velocity of a stretched premixed flame. Up to now, from experimental techniques, this physical property was only accessible in average and the instantaneous interactions of flame with flow structures, mixture variations and walls could not be considered. In the present work, the local burning velocity is measured as the difference between the local flame speed and the local fresh gas velocity at the entrance of the flame zone. Two original methods are proposed to deduce these quantities from pair of particle images. The local flame speed is measured from the distance between two successive flame positions. For the flame localization, a new extraction tool combined with a filtering technique is proposed to access to the flame front coordinates with sub-pixel accuracy. The local fresh gas velocity near the flame front is extracted from the maximum of the normal velocity profile, located within 1 mm ahead of the flame front. To achieve the required spatial resolution, a new algorithm based on adaptive interrogation window scheme has been developed by taking into account the flow and flame front topologies. The accuracy and reliability of our developments have been evaluated from two complementary approaches based, respectively, on synthetic images of particle and on the well-established configuration of outwardly propagating spherical flames. In the last part of the paper, an illustration of the potentials of our new approach is shown in the case of a laminar flame propagating through a stratified mixture.