lightning protection for buildings, towers and personnel

the purpose of a lightning rod and the basic requirements for lightning protection for buildings and towers are discussed. other types of protection such as overhead wires are discussed along with radioactive systems and other dubious elimination schemes. the effects of lightning on persons and animals are also reviewed

fibrin assembly. lateral aggregation and the role of the two pairs of fibrinopeptides

the structural basis of the wide variability of the physical properties of fibrin clots and the process of assembly of the clot were investigated by electron microscopy of fibers formed under various ionic conditions. in addition, highly specific proteolytic enzymes from different snake venoms were used to remove selectively only the a (b..

model system studies on diffuse absorption

optical dosimetry has been investigated in a tissue phantom, consisting of an aqueous suspension of uniform polystyrene spheres plus methylene blue as a chromophore. the rate of light absorption by the dye was measured for different concentrations of dye and scatterers, using the photosensitized inactivation of an enzyme as a sensitive in..

uv-ozone cleaning of gaas (100) surfaces for device applications

gaas (100) substrates were subjected to uv-ozone, wet chemical, and thermal treatments prior to deposition of ni contact structures. the use of uv-ozone showed marked improvement in the electrical characteristics compared to the wet chemical and thermal treatments alone. the major effect of uv-ozone is the nondestructive removal of carbon..

aqueous cleaning of pc boards with smds

the most important consideration in surface mount technology is post soldering cleaning. the purpose of this technical session is to provide information on the effectiveness of various approaches to obtain the best procedure. to remove the multi-chemical processes involved in pc fabrication and assembly may preclude a true understanding o..

xps characterization of gaas surfaces prepared by chemical etching processes frequently employed in microcircuit fabrication

the chemical structure of gaas(100) surfaces treated with various etchants has been examined by x-ray photoelectron spectroscopy (xps). measured peak intensities and chemical shifts in the as and ga 2p levels indicate the formation of a thin (10-15 aa) as/sub 2/o/sub 2/-rich surface oxidized phase, for samples processed with br/sub 2//ch/..

preparation of ultrasmooth surfaces

ultrasmooth and supersmooth are unquantified descriptors commonly used to indicate surfaces with a smoothness near the limit of the current state of the art. such limits usually exceed the state of confirmed, describable technology. they are produced by a process that is an art, and as such can be demonstrated but are often not completely..

the effect of gold-tin intermetallic compound on the low cycle fatigue behavior of copper alloy c72700 and c17200

many connectors and springs fabricated from copper-base spring materials require a gold-plated surface finish. often such parts are joined or interconnected to the electronic package by soldering with tin-lead solder. upon application of heat, the gold plating may interact with the tin contained in the solder to produce a brittle intermet..

design of mode-selective directional couplers for electron cyclotron resonance heating on the mirror fusion test facility

the electron cyclotron resonance heating (ecrh) system will provide microwave energy at 28, 35, and 56 ghz to heat electrons in the thermal barrier and maximum potential regions in the end-plugs of the mirror fusion test facility (mftf-b) tandem mirror machine to design an effective quasi-optical antenna system for ecrh which will convert..

semiconductor analysis using organic-on-inorganic contact barriers. ii. application to inp-based compound semiconductors

organic-on-inorganic (oi) contact barrier devices have been applied to the study of inp and in/sub 0.53/ga/sub 0.47/as surfaces the characteristics of these devices differ from oi diodes fabricated using si or ge substrates in that the contact barriers for inp-based devices are relatively small (