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Notes: Synopsis Assessing accurately the pH of axillary eccrine sweat is of vital importance in the antiperspirant industry. Eccrine sweat pH is a critical parameter in determining the effectiveness of antiperspirants; antiperspirant salts dissolve in sweat and diffuse into the sweat glands, where the resultant acidic solution hydrolyses in more alkaline sweat forming an amorphous metal hydroxide gel, thereby restricting the flow of eccrine sweat. Comparison of the skin surface and sweat pH of males and females reported in the literature shows that, although consistent male/female differences have been observed on the forearm, determination of significant gender-based pH differences across other sites are less conclusive. Studies on the back and infra-mammary regions exhibited significant gender differences in skin surface pH, whereas those on the forehead, cheek, neck and inguinal area showed no such difference. With regard to the axilla specifically, four studies have been reported, three showing no significant difference in axillary skin surface pH and one indicating that females have an eccrine sweat pH of 7 and males have a sweat pH of 5.6.This paper describes a series of carefully controlled studies aimed at assessing potential gender differences in eccrine sweat and skin surface pH following exposure to a variety of temperature, humidity and time conditions. The results highlight the importance of controlling precisely the time of investigation, site of measurement and, most importantly, the necessity to pre-equilibrate samples in 40 mmHg carbon dioxide (equivalent to arterial CO2 tension (pCO2)) before determining sweat pH. When these parameters are controlled no gender differences in axillary sweat or skin surface pH are observed. Large differences in eccrine sweat and skin surface pH are found, however, between the vault (hairy region) and fossa (non-hairy region) of the axilla. Résumé La détermination précise du pH de la sueur au niveau des aisselles est de première importance dans l’industrie des antitranspirants. Le pH de la sueur est un paramètre clef affectant l’efficacité des produits antitranspirants; ceux-ci agissent par diffusion d’une solution d’actifs antitranspirants dans les glandes sudoripares où ils sont hydrolysés et forment un gel amorphe d’hydroxyde métallique limitant ainsi le flux de transpiration. Une comparaison des données publiées dans la littérature sur le pH de la peau et de la sueur chez les hommes et les femmes, révèle que bien que des différences hommes/femmes aient été observées de façon consistente sur l’avant-bras, la différenciation par sexe est moins marquée pour les autres parties du corps. Les études sur le dos et les régions infra-mammaires montrent des différences significatives du pH de la peau; en revanche, celles sur le front, les joues, le cou et la région inguinale ne font apparaitre aucune différence. En ce qui concerne les aisselles, sur quatre études publiées, trois ne montrent aucune différence significative de pH de la sueur et la quatrième indique un pH de 7,0 pour les femmes et de 5,6 pour les hommes, soit une concentration en ions H+ 10 fois plus élevée chez les hommes.Cet article décrit une série d’études méticuleusement controllées visant àévaluer les différences hommes/femmes du pH de la sueur et de la peau en fonction des conditions de temperature, d’humidité et de temps d’exposition. Les résultats démontrent l’importance du contrôle de la durée et du site de mesure et plus particuliérement la nécessité de pré-équilibrer les échantillons à 40 mmHg de dioxide de carbone (équivalent à la tension artérielle de CO2 (pCO2)) avant la mesure de pH. Lorsque ces paramètres sont contrôlés, aucune différence de pH n’est observée entre hommes et femmes au niveau de l’aisselle, ni pour la sueur, ni à la surface de la peau; cependant, des différences importantes sont observées entre la voûte (région pileuse) et la fosse (région non pileuse).

Notes: Abstract The biodiversity of macrofungi in mature and young regrowth Tasmanian wet forests is described at the species level and at the community level. The macrofungal communities studied were much more species-rich than their vascular plant counterparts, with the total number of macrofungal taxa outnumbering vascular plants by four to one. This ratio applied in both mature and young regrowth forest sites. Some 242 taxa of macrofungi were recorded, of which 132 were identified to species level, the remainder to species groups or higher taxa. Distinct communities could be discerned from multivariate analysis (ordination and classification) of vascular plant and macrofungal data from the mature and regrowth sites. The two vascular plant communities had different fire histories, and this difference is also assumed to account for the separation of the macrofungal communities of the two forest types. There was generally a high level of congruence between the vascular plant and the macrofungal communities. However, one young regrowth site, which was relatively close to the mature sites in the ordination space for the analysis of vascular plants, was distant from the mature forest sites for the analysis of macrofungi. Another regrowth site, which had experienced wildfire rather than silvicultural regeneration, clustered with mature sites for some analyses of the macrofungal assemblage. Variation in the macrofungal communities was correlated with a different set of the measured environmental variables than was variation in the vascular plant communities. Mature and young regrowth forests were found to have distinctly different macrofungal floras, with approximately 40% of the taxa in each forest type being restricted to that type of site. Suitable indicator taxa (restricted or preferential to particular forest types) for use in further studies are suggested.

Notes: A study has been made of the reaction rates of mixtures of hydrogen and nitrogen to form ammonia over a doubly promoted iron catalyst at 400° and 450°C. and at pressures up to 1,000 atm. In this work particular care has been taken to obtain data representing the true kinetics of the reaction. The reactor used was essentially isothermal, and the effects of diffusion have been reduced to a minimum. The results have been correlated by the use of the mechanism proposed by Temkin and Pyschev (19) with moderate success.

Notes: The rates of racemisation, under constant conditions of pH and temperature, of two series of ketones with an asymmetric C-atom in α have been determined. As would be expected, substituents in the α position to the keto group influence the rate of racemisation, and it has been found possible to assess the relative electron donating or electron attracting effect of aliphatic, aliphatic-aromatic or aromatic substituents by measuring their influence on the rate of racemisation of a ketone containing the substituent considered.