Showing papers by "Applied Science Private University published in 1969"

Determination of the Firing Temperature of Ancient Ceramics by Measurement of Thermal Expansion

Abstract: THE thermal expansion method for determining firing temperatures1–3 is based on the assumption that, when clays are fired, shrinkage occurs as a result of various sintering processes such as vitrification. Consequently when a clay ceramic is heated up from room temperature (see Fig. 1) it typically exhibits a reversible expansion, characteristic of its mineralogical composition, until temperatures comparable with the original firing temperature are reached. With continued increase in temperature the ceramic begins to contract because superimposed on the reversible expansion there is an irreversible shrinkage associated with resumption of sintering (that is, the firing of the ceramic is being continued beyond the point reached during the original firing). The temperature (Ta) at which a net shrinkage is first observed should therefore provide an indication of the original firing temperature (Te) of the ceramic.

Electrochemical studies on the adsorption of amino acids in relation to the compatibility of prosthetic materials and the human body

Abstract: The Lippman electrocapillary method was used to survey the adsorption behavior of 25 amino acids at the mercury-solution interface. The amount of surface excess of adsorbed amino acid (Γ;), as evidenced by lowering of interfacial tension, was found to increase with the number of double bonds and/or additional nitrogen atoms which provide electron pairs. No influence of dipole moment on adsorption was observed. Adsorption was more extensive at potentials positive to the potential of zero charge, indicating a possible electrontransfer adsorption mechanism, i.e., a sharing π-electrons rather than dipole interaction with the metal. These results are consistant with the enhanced adsorption of proteins at anodic potentials since the side groups extending from peptide linkages on a given protein are the R groups of various amino acids.

Fracture Path of Stress Corrosion Cracks in Austenitic Stainless Steels

Abstract: THE phenomenon of transgranular stress corrosion cracking of austenitic stainless steels in aqueous chloride environments has been recognized for almost 30 yr1. One fact that has had to be included in establishing the mechanism is that the fracture has appeared not to progress along any particular crystal plane2. Only one study3 of single crystals has been reported. Back reflexion Laue photographs revealed that fracture followed no particular plane in specimens of 18Cr–10Ni or 20Cr–12Ni alloys but that it followed {100} planes in specimens of 20Cr–20Ni alloy. In this article we show, by scanning electron microscopy, that the crack follows a crystallographic path even in 18Cr–10Ni steels—an observation not made before. It has been widely suggested that cracks propagate perpendicularly to the operative tensile stress component on both a macro4 and a micro5 scale.

Steady‐State Lateral Movement of Water Through the Unsaturated Zone of an Unconfined Aquifera

Abstract: In a steady-state condition the lateral flow rate through the unsaturated zone of an unconfined aquifer increases with a decreasing rate as the depth of the unsaturated zone increases while hydraulic gradient is kept constant This flow rate reaches a maximum as the depth of the zone is increased This maximum flow rate is computed by various methods such as an aquifer model, graphical integration of the characteristic hydraulic conductivity curve and a flow net diagram Based on these calculations a simple method is outlined for estimation of steady-state flow rate through the unsaturated zone of an unconfined aquifer It is also concluded that in shallow unconfined aquifers the contribution of the flow through the unsaturated zone to the total lateral flow can be significant

Simulation of Earthquake Vibration Effects on a Reactor Fuel Element

Abstract: A UCLA reactor fuel element was subjected to forced vibration tests to determine if vibration-induced changes in the moderator-coolant channel width could cause reactor power fluctuations during an earthquake. The response of the fuel element was monitored by foil-strain gages while the element was vibrated in water. At the natural frequency of the fuel element (11.1) cps, an average coolant channel width increase of 0.0009 in. was observed. We estimate that fuel vibrations with this amplitude could cause a maximum power change of 2.8 % in the UCLA reactor. Several interesting conclusions can be drawn from this work. First, based on our “worst case” analysis it appears that earthquake-induced power oscillations do not pose a reactor safety problem. Careful design (especially to increase rigidity) of fuel elements for power reactors could make the problem of vibration-induced power transients negligible. Second, using the techniques described in the report, it is possible to perform out-of-core experiments...