Sound Signalling in Orthoptera

The sounds produced by orthopteran insects are very diverse. They are widely studied for the insight they give into acoustic behaviour and the biophysical aspects of sound production and hearing, as well as the transduction of sound to neural signals in the ear and the subsequent processing of information in the central nervous system. The study of sound signalling is a multidisciplinary area of research, with a strong physiological contribution. This review considers recent research in physiology and the links with related areas of acoustic work on the Orthoptera

Infrared spectroscopic study of mixed-alkali effect in borate glasses

Infrared spectra of mixed-alkali diborate glasses, (Li, Na)20.2B2O3 and (Li, K)20.2B2O3, have been investigated. B---O stretching and B---O---B bending frequencies exhibit nonlinear shifts which can be described as a mild mixed-alkali effect. Both shifts and nonlinear variations of frequencies may be explained on the basis of alteration of the structure of the diborate groups in the presence of Li+ ions

Infrared spectroscopic study of mixed-alkali effect in borate glasses

Infrared spectra of mixed-alkali diborate glasses, $(Li, Na)_20.2B_2O_3$ and $(Li, K)_20.2B_2O_3$, have been investigated. B-O stretching and B-O-B bending frequencies exhibit nonlinear shifts which can be described as a mild mixed-alkali effect. Both shifts and nonlinear variations of frequencies may be explained on the basis of alteration of the structure of the diborate groups in the presence of $Li^+$ ions

Characterization studies of potassium phosphotungstate glasses and a model of structural units

K<SUB>2</SUB>O-WO<SUB>3</SUB>-P<SUB>2</SUB>O<SUB>5</SUB> glasses have been studied over a wide range of compositions. Their physical, thermal and spectroscopic properties, such as density, molar volume, microhardness, heat capacity, glass transition temperature and infrared special changes has been investigated. A structural model is presented to rationalize the experimental observations. According to this model, binary phosphotungstate glasses are built up of [WO<SUB>6/2</SUB>] octahedral and [POO<SUB>3/2</SUB>] tetrahedral units which share corners. Addition of K<SUB>2</SUB>O to binary phosphotungstates breaks the various linkages present in them. Consequently, a number of structural units are formed and the resulting glasses may be characterized by a network of polyhedra with different numbers of unshared corners. These structural units are consolidated into a structural phase diagram. The colours of these glasses, due to the presence of W<SUP>5+</SUP> ions and their stabilization in the network as [W<SUP>5+</SUP>O<SUB>6/2</SUB>]<SUP>-</SUP> and [PO<SUB>4/2</SUB>]<SUP>+</SUP> structural pairs, are also discussed