Volume 71, Issue 7

Synopsis : This document provides definitions of terms and processes which are used in describing the migration of host and foreign species through solid materials. Both the phenomenological theory of diffusion and the detailed atomistic mechanisms by which atom transport occurs are treated. Also included are the various types of gradients such as electrical, chemical, thermal and mechanical, which provide the driving forces for diffusion.

Among the names and structures used as examples in the 1993 Guide to IUPAC Nomenclature of Organic Compounds some errors appear, several of which are likely to be quickly obvious and untroublesome. To reduce the possibility of confusion among users of the Guide, however, we publish a list of corrections here rather than waiting until a new edition of the Guide has been prepared.

A systematic classification scheme is given for the various types of amplification and related reactions currently available. The report extends and refines earlier IUPAC recommendations ( Pure Appl. Chem. 54 (1982), 2553-2556) to include non-multiplication reactions.

In the last few years scanning probe microscopy techniques have gained significant importance in a variety of different research fields in science and technology. A rapid development, stimulated by the invention of the scanning tunneling microscope in 1981 and still proceeding at a high pace, has brought about a number of new techniques belonging to this group of surface analytical methods. The large potential of scanning probe microscopes is documented by over 1000 publications per year. Due to the fact that a number of different terms and acronyms exist, which are partially used for identical techniques and which are sometimes confusing, this article is aimed at classification and at an overview on the analytically most important techniques with clarification of common terms. Emphasis will be put on analytical evaluation of scanning tunneling and scanning force microscopy, as up to now these techniques have gained the highest importance for analytical applications.

Synopsis : Since the 1960’s there has been a growing body of data regarding the presence of pesticides in the atmosphere. The monitoring results obtained show that traces of pesticides may undergo long range transport and be deposited considerable distances away from the treatment areas, including remote areas such as the Arctic and Antarctic regions. Pesticides have been found in air, rain, cloud water, fog and snow. The appearance and subsequent behaviour of pesticides in the atmosphere are complex processes and the concentrations found depend on several variables such as their volatility, photostability, method of application and extent of use. Whilst volatility of pesticides can be linked to their Henry’s Law constant this is very much a simplification since it is also influenced by the surfaces treated, e.g. soil or leaves, and by the extent to which aerosols are formed during the application. The disappearance of pesticides from the atmosphere is due to hydrolysis, indirect photolysis via OH . radicals and to deposition in rain. Pesticides which are resistant to hydrolysis and photolysis can be transported over great distances, for example, organochlorine insecticides have been detected in the Arctic regions. In general, concentrations in rainwater are, when detected, in the low or sub mg/l range and highest concentrations are found during the time of application. The use of fugacity models has been shown to be a useful approach to predict concentrations in air. Under most conditions the presence of pesticides in air, or rainwater, has no significant effects on non-target systems, including direct and indirect effects. Exceptions to this are damage by auxin-type herbicides to sensitive plants which has resulted on restrictions in their use in certain areas and transient chlorotic spotting thought to be caused by drift of aerosols from application of low rate sulfonyl urea herbicides. For animal species one possible exception has been postulated. This is for persistent organochlorine pesticides in Arctic regions where, due to the very oligotrophic nature of the Arctic ocean, they are more liable to bioaccumulate and be transported in the food web giving enhanced levels in mothers’ milk.