Cavitation bubble collapse studied at 20 million frames per second

The collapse of laser-induced bubbles in water is investigated by high speed photography at framing rates as high as 20 million frames per second. The case of a spherical bubble in an unbounded liquid is compared with the Gilmore model. Bubbles collapsing in front of a solid wall show a rich dynamics depending on their normalized distance. Unprecedented details are given of the generic sequence of events leading to multiple shock waves and bubble shape metamorphosis upon collapse.     

Characterization of the interaction of two oscillating bubbles near a thin elastic membrane

Oscillating bubbles appear in the bodily fluid during many medical treatments, for example in Extracorporeal Shockwave Lithotripsy. We report a systematic study on the complex interaction between two such bubbles and an elastic membrane, which could be a biological membrane in the human body. We have grouped our analysis into similarly sized bubbles, and differently sized bubbles. All bubbles are created at the same time. For the similarly sized bubbles, it can be broadly characterized as the splitting up of two bubbles in vertical direction perpendicular to (vertical split) and at an angle to (oblique split) the membrane surface, jetting towards each other and bubble coalescence. For the two differently sized bubbles, there is the jetting towards or away from the large bubble for the small bubble and the ??catapult?? effect observed. The two bubbles dynamics depend on the relative bubble sizes, the distance from the membrane, and the inter-bubble distance.     

Preparation of ion-implanted silicon for transmission electron microscopy

This paper deals with the preparation technique of thin foils (below 5000 Å) for the transmission electron microscopy from silicon implanted by N⁺ ions. Mechanical and chemical thinning and anodic oxidation techniques are discussed and selective etching of the surface of silicon for the purposes of the replica technique is noted. Compositions of etching solutions and other experimental parameters are mentioned. The results are demonstrated on electron micrographs showing the radiation damage due to ion implantation in silicon.     

UTILIZATION OF TOOLS FOR SUCCESSFUL. TROUBLESHOOTING OF STRUCTURAL PROBLEMS

A structural failure problem was solved using an integrated and iterative program of testing and analysis. The steps taken in solving the problem were: analytical calculations; operational testing; qualifications of analytical results; problem identification; design of corrective action; and confirmatory testing.     

Calculation of the ellipsometric parameters characterizing a randomly rough surface by means of the Stratton-Chu-Silver integral

Considering some simplifying assumptions (especially a moderately rough surface) we present a method for calculating the ellipsometric parameters δ and Ψ characterizing a randomly rough surface. The Stratton-Chu-Silver integral has been used in our approximation. We present also a comparison of the present results with those obtained earlier by means of the Kirchhoff scalar theory.     

Consistency of effective,relativistic four-point interactions for nuclei

We derive consistency conditions for effective field theoretic models for nuclei with four-fermion couplings. The transformation properties of these consistency conditions under the renormalization group are discussed.Supported by Gesellschaft für Schwerionenforschung (GSI)