Isopropyl alcohol recovery by heteroazeotropic batch distillation

Solvent recovery is becoming a major issue in the pharmaceutical and specialty chemical industries. Solvent recovery by conventional batch distillation is limited by the frequent presence of azeotropes in the used solvent mixtures. Most distillation processes for the separation of azeotropic or difficult zeotropic mixtures involve the addition of an entrainer (homogeneous and heterogeneous azeotropic distillation or extractive distillation). In this study the recovery of IPA (isopropyl alcohol) from an industrial waste stream (IPA/water mixture) was studied by conventional batch distillation and heteroazeotropic batch distillation, using cyclohexane as entrainer. First the ternary IPA/water/cyclohexane azeotrope (boiling temperature of 64.1 °C), then the binary IPA/cyclohexane azeotrope (boiling temperature of 69.3°C) and finally pure IPA was distilled. 99.96 mass% IPA could be obtained by heteroazeotropic distillation, using cyclohexane as entrainer. By using this procedure the IPA recovery is 97.6%, which is high compared to the conventional distillation techniques. The binary azeotrope could be reused in a subsequent heteroazeotropic batch distillation

Studies on the reproductive status, catch and age compositions of the tsetse fly, Glossina pallidipes populations in the Nechisar National Park in southern Ethiopia

Studies were conducted during the dry hot period of December 1999 to April 2000 in the Nechisar National Park, Southern Ethiopia, to obtain base line data on catch, age compositions, and reproductive status of samples of Glossina pallidipes, trapped in NGU-2G traps. The objective was to assess tsetse population dynamics and to provide data on the temporal and spatial variations of the structure of the fly population at five localities (habitats). The data were to be used for the suppression phase of a Sterile Insect Technique (SIT) project in the study area. Population study in space was conducted at randomly selected five sites in and out of the park. In each vegetation type, a set of 2 NGU-2G traps baited with urine and acetone were deployed for five days during the same week of the study time. Female flies were dissected to assess ovarian age structure of populations. To determine the age of male flies wing-fray analysis was carried out using wing-fray categories (1-6). Trapped tsetse included significantly higher proportions of teneral and non-teneral females, and a lower male: female ratio. Insemination rates of the sampled flies were over 95% at all habitats. In any one habitat, the frequency of pregnancy (egg stage) predominated, followed by the first, second, and lastly, by the third instar larva. Abortion was the predominant reproductive abnormality at all habitats of the natural population of G. pallidipes. Age compositions of females (ovarian aging) showed greater proportions of females with 1–3 ovarian age categories and a physiological age between 8–40 days at all habitats. Age compositions of males (wing-fray) were significantly greater for young males (1–3 wfc) compared with old males (4–6 wfc). The studies of this base line data collection with other operational studies will be a prerequisite to assess the feasibility of the proposed area wide eradication project and to develop appropriate strategies to suppress and finally to eradicate the fly by situational releases of sterilized male flies.Key words/phrases: Abortion, age reproductive status, Glossina pallidipes, NGU-2G traps, pregnancy SINET: Ethiopian Journal of Science Vol. 28 (1) 2005: 51-6

Radiation induced sterility to control tsetse flies : the effect of ionising radiation and hybridisation on tsetse biology and the use of the sterile insect technique in integrated tsetse control

The induction of dominant lethal mutations by exposing tsetse flies as pupae or adult insects to ionising radiation and the use of hybrid sterility resulting from crosses of closely related tsetse species or subspecies, are potential methods of genetic control of tsetse flies. In this thesis the effects of radiation and hybridisation on the reproductive biology and fitness of several species of tsetse flies has been examined. In addition, aspects of field releases of sterile insects have also been examined.</p

Effects of laboratory colonization on Bactrocera dorsalis (Diptera, Tephritidae) mating behaviour: 'what a difference a year makes'

Laboratory-reared insects are widely known to have significantly reduced genetic diversity in comparison to wild populations; however, subtle behavioural changes between laboratory-adapted and wild or ‘wildish’ (i.e., within one or very few generations of field collected material) populations are less well understood. Quantifying alterations in behaviour, particularly sexual, in laboratory-adapted insects is important for mass-reared insects for use in pest management strategies, especially those that have a sterile insect technique component. We report subtle changes in sexual behaviour between ‘wildish’ Bactrocera dorsalis flies (F1 and F2) from central and southern Thailand and the same colonies 12 months later when at six generations from wild. Mating compatibility tests were undertaken under standardised semi-natural conditions, with number of homo/heterotypic couples and mating location in field cages analysed via compatibility indices. Central and southern populations of B. dorsalis displayed positive assortative mating in the 2010 trials but mated randomly in the 2011 trials. ‘Wildish’ southern Thailand males mated significantly earlier than central Thailand males in 2010; this difference was considerably reduced in 2011, yet homotypic couples from southern Thailand still formed significantly earlier than all other couple combinations. There was no significant difference in couple location in 2010; however, couple location significantly differed among pair types in 2011 with those involving southern Thailand females occurring significantly more often on the tree relative to those with central Thailand females. Relative participation also changed with time, with more southern Thailand females forming couples relative to central Thailand females in 2010; this difference was considerably decreased by 2011. These results reveal how subtle changes in sexual behaviour, as driven by laboratory rearing conditions, may significantly influence mating behaviour between laboratory-adapted and recently colonised tephritid fruit flies over a relatively short period of time

Dynamics of spatial frequency tuning in mouse visual cortex

Neuronal spatial frequency tuning in primary visual cortex (V1) substantially changes over time. In both primates and cats, a shift of the neuron\u27s preferred spatial frequency has been observed from low frequencies early in the response to higher frequencies later in the response. In most cases, this shift is accompanied by a decreased tuning bandwidth. Recently, the mouse has gained attention as a suitable animal model to study the basic mechanisms of visual information processing, demonstrating similarities in basic neuronal response properties between rodents and highly visual mammals. Here we report the results of extracellular single-unit recordings in the anesthetized mouse where we analyzed the dynamics of spatial frequency tuning in V1 and the lateromedial area LM within the lateral extrastriate area V2L. We used a reverse-correlation technique to demonstrate that, as in monkeys and cats, the preferred spatial frequency of mouse V1 neurons shifted from low to higher frequencies later in the response. However, this was not correlated with a clear selectivity increase or enhanced suppression of responses to low spatial frequencies. These results suggest that the neuronal connections responsible for the temporal shift in spatial frequency tuning may considerably differ between mice and monkeys