Electro-Optical Analysis of Cell Viability of Tularemia Microbe Vaccine Strain

Objective: to study the possibility of applying electro-optical analysis for the assessment of cell viability of tularemia microbe vaccine strain at different stages of experimental live tularemia vaccine production.Materials and methods. The research object was a cell culture of Francisella tularensis 15 NIIEG. Investigations were carried out at all stages of experimental live tularemia vaccine (ELTV) manufacturing according to an advanced technology: cultivation, concentrating, diafiltration, mixing with drying media, stabilization, and storage (two-year period of observation). Electro-optical analysis by the parameter “polarizability anisotropy” of bacterial cell was conducted with the help of EloTrace (EloSystems, Germany). Total concentration of cells was evaluated using density metering at 590 nm and spectrometry – at 650 nm. Viability was assessed through inoculation of plates with FT-agar.Results and discussion. The experiment has demonstrated that the change in polarizability anisotropy of the cell at the frequencies of 900 kHz and 2100 kHz, reflecting the state of cytoplasm and cytoplasmic membrane, respectively, is the earliest response to changes in vital indicators of bacterial culture in the process of cultivation. Thereby, the decrease in viability of F. tularensis cells occurrs well before the decrease in cell concentration. We have shown the preservation of viability of F. tularensis 15 NIIEG cells at all stages of experimental live tularemia vaccine production. Electro-optical analysis allows for registering the changes in vital parameters of microorganism cells in real-time mode, while the assessment of viability applying bacteriological method takes up to 5 days. Different stages of tularemia vaccine manufacturing have impact on the vital indicators of F. tularensis cells, and electro-optical analysis is a prospect method of control of such parameter as “Specific activity (the number of live microbial cells)”.

DFT calculations on polarizabilities and hyperpolarizabilities for the neutral and anionic yttrium oxide clusters

The electronic properties, polarizabilities, first and second hyperpolarizabilities of YOn clusters of [Formula: see text]–12 were studied using the quantum chemical method. The vertical ionization potential (VIP) values for the anionic clusters increase monotonically with the cluster size. Among the neutral clusters YO3 and YO8 have the least chemical hardness values, where in anionic clusters with size [Formula: see text] possesses the least chemical hardness. Anionic clusters have more electrons attracting tendency than the neutral clusters. The computed static mean polarizability of neutral yttrium oxides has positive values but is close to zero. The incorporation of oxygen atom quenches the polarizability of yttrium. The computed polarizability anisotropy of neutral clusters shows an oscillatory effect both at static and at dynamic conditions. The first hyperpolarizability for many YOn clusters are close to zero. The existence of high symmetry in these clusters reduces the first hyperpolarizability values which was supported by the small dipole moments. The computed [Formula: see text] values for the static neutral and anionic clusters show only a small variation. The decrease in the polarizability and second hyperpolarizability with size can be interpreted in terms of the electronic delocalization and chemical bonding in the clusters.

An Optical Study on Orientational Order Parameter and Molecular Polarizability in Benzylidene Anilines

Refractive indices measurements are carried out in four alkoxy benzylidene anilines viz., N-(p-n-methoxy and ethoxy benzaldehyde)-p-n-dodecyl and tetra decyl anilines, 1O.12, 1O.14, 2O.12 and 2O.14. First three compounds exhibit monovariant nematic phase while the last compound exhibits nematic and SmA phases with variable thermal ranges. The molecular polarizabilities are calculated from the refractive indices and the density using the well known internal field models by Vuks and Neugebauer. The molecular polarizability anisotropy is estimated from the Lippincott δ-function model as well as molecular vibrational methods. The order parameter is estimated using a) from the Haller’s extrapolation from molecular polarizabilities, b) from the scaling factors obtained from the equations by Vuks and Neugbeaur and c) directly from the birefringence - a method developed by Kuczynski et al without considering any internal field model to the liquid crystal molecule. The results evaluated from these methods are compared from one another and the limitations of the methods used are discussed.