Space processing on Skylab and ASTP

The Skylab and Apollo Soyuz Test Project (ASTP) missions provided the opportunity the influence of micro-gravity on the processing of various materials. The results of physical and engineering experiments in metallurgy, fluids handling and crystal growth on two space missions are discussed. The majority of the experiments concern the solidification of alloys, semiconductors, and composite materials or basic liquid-liquid and solid-liquid interactions necessary to understand complex processing. Potential advantages of space processing to several materials disciplines are identified

Electrophoresis device

A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected

Method of crystallization

A method is described for refining or growing bulk single crystals in an environment substantially free of gravity. The base material is suspended, positioned, and shaped as a containerless melt by wetting forces. Because no crucible is required, high temperature refractory materials can be processed

Determination of amino acids and nitrates in soils: amino acids, ammonia and nitrates in manured and limed soil

In view of the fact that no data had ever been obtained on the quantitative relationships of the organic material in the soil by such methods as would preclude a chemical transformation, two things seemed desirable, in continuing the humus investigations at the Iowa Agricultural Experiment Station. First, to attempt the analysis of the organic material of the soil without subjecting it to hydrolysis or other chemical change, and second, to correlate the proportionate quantities of the compounds or classes of compounds found with the kind of soil, its history, treatment, fertility, etc

Carbon dioxide production in soils and carbon and nitrogen changes in soils variously treated

The carbon dioxide of the soil atmosphere, along with the water, has long been recognized as the most active agent in the decomposition of comparatively inert minerals to give available and soluble plant food material. It is probable that herein lies the great benefit which comes from the application to soil of organic material which not only increases the energy material easily available for the bacteria, but also improves the physical condition of the soil. This in turn increases bacterial activity, which gives rise to increased carbon dioxide production. At the Iowa Agricultural Experiment Station, for some time past, both in the laboratory and in the field, determinations have been made of the carbon dioxide of the soil atmosphere or of the carbon dioxide evolved by soils. These experiments have been carried out with the primary object of obtaining information as to the rate of decomposition of the soil or of organic matter added to the soil, under various conditions and treatments. In this paper attention will be confined mainly to the production of carbon dioxide by soils and its measurement. Little will be said concerning its effectiveness as an agent for rendering plant foods available

The determination of ammonia in soils

Theoretically, the ideal method for determining ammonia in soils would give the absolute amount of ammonia present as such and as the ammonium radical, but in the light of present knowledge, it cannot be said beyond all doubt that any conceivable method would give this ideal result. This is true because a large part of the nitrogen of the soil is present in protein and protein degradation products, the extensive decomposition of which gives large amounts of ammonia. The uncertainty regarding just what products are present does not permit the finding of conditions which we can be certain will expel ammonia already present and not decompose any material to give, among other products, ammonia. The problem is further complicated by the well known absorptive and adsorptive powers of the soil

Flow and thermal effects in continuous flow electrophoresis

In continuous flow electrophoresis the axial flow structure changes from a fully developed rectilinear form to one characterized by meandering as power levels are increased. The origin of this meandering is postulated to lie in a hydrodynamic instability driven by axial (and possibly lateral) temperature gradients. Experiments done at MSFC show agreement with the theory

Shock tube measurements of growth constants in the branched-chain ethane-carbon monoxide-oxygen system

Exponential free radical growth constants have been measured for ethane carbon monoxide oxygen mixtures by monitoring the growth of oxygen atom concentration as manifested by CO flame band emission. Data were obtained over the temperature range of 1200 to 1700 K. The data were analyzed using an ethane oxidation mechanism involving seven elementary reaction steps. Calculated growth constants were close to experimental values at lower temperatures, up to about 1400 K, but at higher temperatures computed growth constants were considerably smaller than experiment. In attempts to explain these results additional branching reactions were added to the mechanism. However, these additional reactions did not appreciably change calculated growth constants

The homomorphism threshold of {C₃,C₅}-free graphs

We determine the structure of {C₃,C₅}-free graphs graphs with n vertices and minimum degree larger than n/5: such graphs are homomorphic to the graph obtained from a (5k - 3)-cycle by adding all chords of length 1(mod 5), for some k . This answers a question of Messuti and Schacht. We deduce that the homomorphism threshold of {C₃,C₅}-free graphs is 1/5, thus answering a question of Oberkampf and Schacht