Surface waves in a periodic two-layered elastic half-space with the boundary normal to the layering

The paper deals with the problem of surface waves in a vertically layered elastic half-space. The transmitting medium is composed of periodically repeated two-constituent laminae, and its boundary is assumed to be normal to the layering. The problem is solved using an approximate model proposed by Wo?niak (Int J Eng Sci 25:483–499, 1987) and Matysiak and Wo?niak (Int J Eng Sci 25:549–559, 1987), which is referred to as the homogenized model with microlocal parameters. The velocity of the surface wave is obtained as a function of geometric and dynamic properties of the laminae. The variation of the surface wave velocity with respect to composite constituents is illustrated by numerical examples.     

Derivatives of 1,4‐naphthoquinone as visible‐light‐absorbing one‐component photoinitiators for radical polymerisation

Bifunctional visible‐light photoinitiators for free radical polymerisation based on a 1,4‐naphthoquinone skeleton were synthesised and characterised using proton nuclear magnetic resonance spectroscopy and chemical ionisation mass spectrometry. Their basic spectroscopic properties, such as absorption and low‐temperature phosphorescence spectra, and their red‐ox properties were also measured. These initiators contain an appropriate electron/hydrogen donor group in the skeleton and do not require an additional coinitiator for initiation. During irradiation they act both as a triplet photosensitiser and as a hydrogen/electron donor. The ability of each naphthoquinone to act as a photoinitiator strongly depends on its chemical structure. These studies suggest that initiator radicals are generated from the triplet state in an intermolecular electron/hydrogen transfer reaction.     

A biomechanical aspect of the lumbal approach to the kidney

Functional differences between surgically attacked musculature of the lumbal region and intact musculature of the contralateral side were assessed in 71 patients by the method of Multi?-Labar, Moire topography, electromyography and X-ray analysis of the thoraco-lumbar spine. The following conclusions were derived from the results obtained. In the intact musculature of the lumbal segment of the spine, sliding forces reached 200 kN in males an 170 kN in females aged >25 and <30 years. In younger and older age groups, the values were lower, assuming a form of the ascending and descending limb of a parabole, respectively. Upon healing, the lumbal musculature damaged by surgical resection showed decreased values of the pulling and sliding forces by 15 and 25 kN on an average, respectively, as definite values independent of age and sex. Kinematic alterations included myogenic geneses of a stationary form, with normal innervation, involving the whole damaged musculature. Summa summarum, results of analyses suggested the values of kinematic forces of pulling and sliding forces of the musculature damaged by surgical resection to be definitely significantly reduced, thus confirming the premise of the study.