Dependence of Mesogen Molecules Interaction Energy on their Mutual Orientation

For interaction energy of mesogenic model rod-like molecules an analytical expression is obtained. Interaction energy of dipole moments interaction is much less than the total interaction energy. The empirical Rapini-Papoulard potential for the free surface energy of liquid crystals corresponds well with a limiting case of the expression obtained for small orientation angles

Dependence of Mesogen Molecules Interaction Energy on their Mutual Orientation

For interaction energy of mesogenic model rod-like molecules an analytical expression is obtained. Interaction energy of dipole moments interaction is much less than the total interaction energy. The empirical Rapini-Papoulard potential for the free surface energy of liquid crystals corresponds well with a limiting case of the expression obtained for small orientation angles

Effect of photoaligning azo dye structure on liquid crystal anchoring energy

A method of controlling anchoring energy of surface interaction of liquid crystal photoaligning substances is considered to enhance the liquid crystal display performances. An important parameter of the dye's molecular structure that determines the ratio of polar and azimuthal anchoring energy is the ability to form dimers. The values of dimerization thermodynamic potentials have been found. The probability of the formation of dye molecules dimers is evaluated. The bonds conjugation transfer via intermolecular hydrogen bond is revealed, and anisotropy of polarizability of the hydrogen bond is evaluated. The effect of dimerization on polar and azimuthal anchoring energy of liquid crystal - azo dye system - is shown. A method to control liquid crystals anchoring energy with photoaligning substances is considered to enhance the liquid crystals display performances. Azo dyes with molecules that form dimers via intermolecular hydrogen bond provide higher ratio of polar and azimuthal anchoring energy than dyes whose molecules do not form such dimers. The dimerization thermodynamic potentials and the probability of the formation of the dye molecules' dimers have been estimated. © Copyright 2015 Society for Information Display

Bacterial adhesion on the rock fragments immersed in wells in the equatorial region of Cameroon (Central Africa): a study on the potential effect of the day and night immersion period

This study aims to evaluate the abundance of heterotrophic aerobe bacteria (HAB) adhered during the dayperiod and the night to fragments of granite, basalt and migmatite immersed in 2 well water points. Theincubation periods were 12h in day time, 12h at night and 24h (day and night). For the 2 wells the highestabundance of the HAB adhered on granite, basalt and migmatite varied respectively from 11.20 to 11.94, 11.49 to11.54 and from 12.16 to 13.68 (Log (CFU/cm2)) during the day period, respectively from10.92 to 12, 10.40 to11.37 and from 10.20 to 11.79 (Log (CFU/cm2)) during the night period, and respectively from 10.70 to 11.13,10.47 to 10.59, and from 10.56 to 11.17 (Log (CFU/cm2)) during the 24h incubation period. The abioticparameters considered and assessed at 6 am on each sampling day were pH, electrical conductivity, totalsuspended solids, color, turbidity and the water column thickness. The Principal Component Analysis (PCA)showed for each of rock-type, a relative variation with respect to incubation period of the percentage ofinformation contained in each principal axis. This could be due to the substantial influence of incubation periodand some meteorological parameters on hydrological properties of water as well as the bacterial and rockfragmentsurface.info:eu-repo/semantics/publishe

Effect of photoaligning azo dye structure on liquid crystal anchoring energy

A method of controlling anchoring energy of surface interaction of liquid crystal photoaligning substances is considered to enhance the liquid crystal display performances. An important parameter of the dye's molecular structure that determines the ratio of polar and azimuthal anchoring energy is the ability to form dimers. The values of dimerization thermodynamic potentials have been found. The probability of the formation of dye molecules dimers is evaluated. The bonds conjugation transfer via intermolecular hydrogen bond is revealed, and anisotropy of polarizability of the hydrogen bond is evaluated. The effect of dimerization on polar and azimuthal anchoring energy of liquid crystal - azo dye system - is shown. A method to control liquid crystals anchoring energy with photoaligning substances is considered to enhance the liquid crystals display performances. Azo dyes with molecules that form dimers via intermolecular hydrogen bond provide higher ratio of polar and azimuthal anchoring energy than dyes whose molecules do not form such dimers. The dimerization thermodynamic potentials and the probability of the formation of the dye molecules' dimers have been estimated. © Copyright 2015 Society for Information Display

Polar and azimuthal anchoring energy of liquid crystals

The interaction energy between mesogenic molecules (diphenyl, pentylbiphenyl and 4-n-octyl-4′-cyanebiphanyl) and the graphite and PE surface has been calculated using atom-atom potentials method. Polar and azimuthal anchoring energies are obtained and their dependences on the order parameter were derived. The good coincidence of calculated values of anchoring energies as well as of their dependences on the order parameter with experimental data is shown

Impact of Rainfall and Some Water Abiotic Factors on theAbundance Dynamic of Vibrio and Aeromonas Adhered toCopepods Surface in Some Coastal Streams and Rivers inCameroon (Central Africa)

International audienceA study was carried out on the tributaries draining into Rivers in the coastal region of Cameroon(Central Africa). It aimed at assessing the abundance of Vibrio and Aeromonas cells adhered to copepods withrespect to some considered abiotic factors. It has been noted that the tributaries are substantially concentratedin organic matter and these fluctuated, depending on the amount of rainfall received by the rivers throughoutthe period of the study. The abundance of Aeromonas cells adhered to copepod fraction ranged from 38CFU.Ind-1 to 8×103 CFU.Ind-1. That of Vibrio cells ranged from 75×102 CFU.Ind-1 to 42.4×103 CFU.Ind-1. Ofthe total bacteria identified in this study, V. cholerae relatively dominated the bacterial community (38%),followed by A. sobria (30%), A. hydrophila (27%) and other species namely V. alginoticus, V.parahaemolyticus, V. mimicus, V. vulnificus, A. cavia, Aeromonas sp. represented 5%. From the PrincipalComponent Analysis (PCA) assessing the influence of abiotic factors in the abundance changes of bacteriaattached to copepods, it appears that the first cloud of points includes the rainfall, pH, Aeromonas and Vibriowhile the second cloud on the left pole groups namely water temperature, salinity, carbon dioxide andoxydability. Vibrio and Aeromonas cells preferentially colonized copious quantities of copepods during theperiod of excess flood when the concentration of nutrients in the water column regressed. A complex network ofabiotic factors thus acts in synergy to influence the attachment of Aeromonas and Vibrio cells to copepods. Toprevent the risk of cholera outbreaks and non-cholera infections, ecological monitoring should be furtherenhanced during the period of excess rainfall

Involvement of cell shape and flagella in the bacterial retention during percolation of contaminated water through soil columns in tropical region

Microorganisms' retention in soil contributes to the natural purification of groundwater. Bacteria found in groundwater are generally of various shapes. The aim of this study was to assess the importance of cell shape and flagella in bacterial retention during polluted water percolation through two soil columns CA and CB, in the equatorial region in Central Africa. Percolation tests were carried out using different water loads samples which were contaminated by Escherichia coli (straight rods, peritrichous flagella), Vibrio parahaemolyticus (rods bacteria, polar flagella), and Staphylococcus saprophyticus (spherical, free-flagellum). It has been noted that showed that through soil column CA, the mean values of cells retention ratios (TR) varied with bacteria species considered, and from one applied water load sample to another. E. coli TR and that of S. saprophyticus were not significantly different (P> 0.05) for the two soil columns. V. parahaemolyticus TR significantly differed from that of E. coli and S. saprophyticus through soil column CA (P< 0.01) when the highest water load was applied, and through soil column CB (P< 0.05) for each of water load applied. A relative hierarchical arrangement of retained cells based on the TR showed that V. parahaemolyticus was less retained through the 2 soil columns. S. saprophyticus in most cases was more retained than others. The physical properties of the bacterial cell must be taken into consideration when evaluating the transfer of bacteriological pollutants towards groundwater.SCOPUS: ar.jinfo:eu-repo/semantics/publishe