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PubMed1986

A note on eggshell porosity, nest humidity and the effects of DDE in the grey heron (Ardea cinerea).

Water vapour conductance (GH2O) was determined for 25 grey heron Ardea cinerea eggs in the laboratory, and in nests during natural incubation at two Scottish colonies. The mean GH2O of eggs measured in the nest which successfully hatched was 9.0 mgH2O/mmHg/day and the mean water vapour pressure gradient between egg and nest (delta PH2O), measured using "calibrated" duck eggs, averaged at 31 mmHg (4.13 kPa). Based on eggshell porosity results, from the eggs which hatched, such a gradient would result in a loss of water from the eggs during incubation equivalent to 11% of their fresh weight. Shell thickness, the number of pores/cm2 of eggshell and DDE content were also determined for the 25 eggs measured in the laboratory. Eggs containing high levels of DDE had thinner shells, more pores in the eggshell and a higher overall eggshell porosity. The main problem posed by a high level of DDE would appear, however, not to be an excessive water loss from the egg during incubation, but rather eggshell thinning leading to a loss of the egg due to breakage in the nest.

Animals↗
PubMed2004

The crystallisation of a model hydrophobic drug (terfenadine) following exposure to humidity and organic vapours.

Terfenadine was selected as a model drug as it readily converts to the amorphous form, is chemically stable and is hydrophobic. Amorphous terfenadine beads were exposed to water vapour (different RH values) and the change in crystallinity was monitored using isothermal microcalorimetry. It was found that a small amount of the surface crystallised and then the process stopped (after about 9 weeks even though storage continued for ca. 2 years). The self-limiting crystallisation was due to water having limited access to the surface, believed to be at certain cracks and pores. Water sorption data were modelled such that it was possible to compare rates of sorption at different RH values and on fresh and aged material. It was shown that sorption was slower with reducing RH and also much slower on aged samples that had relaxed and reduced the size of surface defects. Mixtures of ethanol and water yielded a vapour that produced increasing rates of crystallisation as the ethanol content increased, but which only crystallised the outer surface of the beads and not the core. A mixture of ethanol and n-propanol caused complete crystallisation, because the propanol was sufficiently hydrophobic to absorb throughout the bead and lower Tg. An isothermal microcalorimetry method was described that allowed quantification of the amorphous content. The work has demonstrated the complexity of the crystallisation of hydrophobic amorphous materials when exposed to various vapours.

Crystallization↗
PubMed2004

Plasmachemical degradation of azo dyes by humid air plasma: Yellow Supranol 4 GL, Scarlet Red Nylosan F3 GL and industrial waste.

A recent non-thermal plasma technique (i.e., a gliding arc discharge which generates reactive species at atmospheric pressure) is tested for pollution abatement of dyes dispersed in synthetic solutions and industrial effluents. Yellow Supranol 4 GL (YS) and Scarlet Red Nylosan F3 GL (SRN) are toxic synthetic dyes widely used in the Algerian textile industry and frequently present in liquid wastes of manufacture plants. Classical removal treatment processes are not efficient enough, so that the presence of dyes in liquid effluents may cause serious environmental problems, in connection with reusing waste waters for irrigation. The degradation processes achieved by the oxidising species formed in the plasma are followed by UV/VIS spectroscopy and by chemical oxygen demand measurements. They are almost complete (i.e., 92.5% for YS and 90% for dilute SRN) and rapidly follow pseudo-first-order laws, with overall estimated rate constants 3 x 10(-4) and 4 x 10(-4)s-1 for YS and SRN, respectively. The degradation rate constant for the industrial mixture (i.e., k = 1.45 x 10(-3)s-1) is a mean value for two consecutive steps (210(-3) and 6 x 10(-5)s-1) measured at the absorption peaks of the major constituent dyes, YS and SRN.

Air↗