In the present work the surfaces of the polyacrylonitrile (PAN)-based carbon fibers were physically treated using cold plasma in argon and oxygen atmospheres, in order to modify and improve the fine mechanical properties of the carbon fibers used in the fiber reinforced polymer composites. The physical and morphological changes of the surfaces were investigated by tensile strength tests and scanning electron microscopy (SEM). It was found that the oxygen plasma treatments caused ablation of the carbon fiber surface, removing carbon atoms such as CO and CO2 molecules. In addition, the argon plasma treatment eliminated defects on the fiber surface, reducing the size of critical flaws and thus increasing the fiber’s tensile strength. A comparison of the methods applied provides a largely consistent image of the effect of plasma treatment on the fine mechanical properties. and V této práci jsou fyzikálně zkoušeny povrchy polyakrylonitrilových (PAN) vláken pomocí chladného plazmatu v argonové a kyslíkové atmosféře s cílem modifikovat a zdokonalit mechanické vlastnosti uhlíkových vláken používaných ve zpevněných polymerových kompozitech- Fyzikální a morfologické změny povrchů byly zkoušeny na pevnost v tahu a pomocí rastrovací elektronové mikroskopie (SEM). Bylo zjištěno, že obrábění kyslíkovým plazmatem způsobilo ablaci povrchu uhlíkového vlákna odstraněním uhlíkových atomů v molekulách CO a CO2. Argonové plazma kromě toho eliminovalo defekty na povrchu vlákna snížením velikosti kritických vad a tím způsobilo zvýšení pevnosti v tahu. Srovnání použitých metod poskytuje široce konzistentní obraz vlivu plazmového obrábění na mechanické vlastnosti.
We have obtained chopped near-infrared maps at 1.25, 1.65 and 2.2 micron in the Serpens dark cloud (S68) centered on IRS3. They show unresolved structure, most likely due to illumination of scattering grains, out to 1´ from the center. The combination of high reddening (and 3.07 m absorption) and asymmetrical optical reflection points to a non-spherical dust distribution typical for
bi-polar flow sources. In addition to the maps at 3,H,K, which consist of 19 by 47 pixells spaced by 2, we are using (Gunn r. and z) CCD images taken at Palomar by Bel Campbell. We are developing software to process these and similar intrared maps using a modified maximum entropy technique. The modifications have been necessary, to avoid singularities inherent in the standard maximum entropy algorithm when it is applied to data with zerovolume point-spread functions.
The present paper deals with the force function´s transformation in the general threebody problem in Jacobi´s coordinates. In this transformation we make use of Rose´s idea about the traslation of the spherical functions in Quantum Electrodynamics.
In order to investigate the ability of infective larvae of the nematode Baylisascaris transfuga (Rudolphi, 1819) Sprent, 1968 to hatch from the egg-shells and then to migrate in tissues, parenteral infections of mice with embryonated eggs were performed. Two groups of outbred albino mice were infected with approximately 3500 B. transfuga infective eggs sub-cutaneously (SC) or intraperitoneally (IP). B. transfuga larvae in the IP group rapidly hatched and migrated to the intestine, liver, lungs, brain and carcass. Subcutaneous inoculation of eggs was followed also by migration of hatched larvae in the examined organs. In the SC mice, extensive encapsulating reactions involving the subcutaneous tissues and carcass, and containing large numbers of hatched eggs and free motile larvae, were found at the sites of inoculation. Some differences in the migratory behaviour were observed between the two groups. It is shown that B. transfuga infective larvae are able to hatch and migrate in tissues of mice, and tend to settle and/or to be trapped in the intestinal wall and muscles, even after parenteral inoculations of embryonated eggs. These results could provide basic data for further investigations on the migratory pathways of B. transfuga larvae or to perform immunological and therapeutical studies.
Numerous spectrograms of Halley’s Comet have been taken by the author during October 1985 - May 1986 with the Hissar astronomlcal observatory 70-cm reflecting telescope AZT-8 and SPM-1 spectrograph giving a dispersion of 160 A/mm. A two
cascade image intensifier with fiber optics and Kodak 103 aG emulsion have been used. On the basis of four red and near IR spectra taken on 16 December 1985 with 5 to 40 min exposures a set of provisional identifications shown in the Table was given.