Friction diagram of the helically coiled tube

The pressure drop in helical coils can easily be calculated with good precision. The required friction factor λ can be taken from the friction diagram presented in this paper. The diagram also offers a graphic view of the pertinent parameters and the flow condition (laminar or turbulent) in the helically coiled tube.     

Signed line intercept count

Elements of surfaces that bound a phase (β) in a two phase mixture (α+β) may be classified as: (a) convex (++) if both principal curvatures are positive; (b) concave (? ?) if both are negative; and (c) saddle (+ ?) if one is positive and the other negative. This classification excludes the limiting cases for which one or both of the principal curvatures is zero. The traces of these surfaces that form the boundaries of the β areas on a representative two dimensional section may also be: (a) convex (+) if the local curvature is positive; or (b) concave (?) if it is negative. Line intercepts may be tabulated separately for intersections with convex (+) and concave (?) segments of boundary. This paper presents a derivation of fundamental stereological formulae that relate these counting measurements to three-dimensional geometric properties of the structure they sample.     

Method for the simultaneous determination of residues of chemotherapeutic agents, antiparasitic agents and growth promoters in food of animal origin. 3. Determination of chloramphenicol and meticlorpindol

Chloramphenicol and meticlorpindol may be determined by HPLC with UV-detection with a limit of 0.02-0.03 mg/kg. Residues of 0.001 mg/kg Chloramphenicol are determined by Capillary-GC with an ECD after an additional clean up step using chromatography on a miniaturized silica column, followed by a silylation step. HMDS/TMCS/Pyridine forms the disilylated Chloramphenicol. In samples of eggs, milk and meat the limit of detection is roughly 0.0002 mg/kg and is adequate to check the FDR tolerance levels for these foods. The proposed method was checked with residues of chloramphenicol in the range of 0.0005 to 0.005 mg/kg in milk from animals dosed with chloramphenicol. Results obtained by this method and results of a RIA-method correlated very well. The analytical procedure (applicable for all substances) was abbreviated compared to the method reported in the first communication on this topic.     

Study of possibilities for a spin flip in high energy electron ring HERA

In a high energy electron ring the spins of electrons become spontaneously polarized via the emission of spin-flip synchrotron radiation. By employing a radio frequency radial dipole field kicker, particle spin directions can be rotated slowly over many turns. A model which couples three dimensional spin motion and longitudinal particle motion was constructed to describe nonequilibrium spin dynamics in high energy electron storage rings. The effects of a stochastic synchrotron radiation on the orbital motion in the accelerator synchrotron plane and its influence on the spin motion are studied. The main contributions to the spin motion, the synchrotron oscillations and the stochastic synchrotron radiation, have different influence on the spin polarization reversal in different regions of the parameter space. The results indicate that polarization reversal might be obtained in high energy electron storage rings with a significant noise even with relatively small strengths of a perturbing magnetic field. The only experimental datum available agrees with the model prediction, however further experimental data would be necessary to validate the model.     

A method to study the history of a double oxide film defect in liquid aluminum alloys

Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied. This article is based on a presentation made in the John Campbell Symposium on Shape Casting, held during the TMS Annual Meeting, February 13–17, 2005, in San Francisco, CA.