Dynamic transitions through scattors in dissipative systems

Scattering of particle-like patterns in dissipative systems is studied, especially we focus on the issue how the input-output relation is controlled at a head-on collision where traveling pulses or spots interact strongly. It remains an open problem due to the large deformation of patterns at a colliding point. We found that a special type of unstable steady or time-periodic solutions called scattors and their stable and unstable manifolds direct the traffic flow of orbits. Such scattors are in general highly unstable even in the one-dimensional case which causes a variety of input-output relations through the scattering process. We illustrate the ubiquity of scattors by using the complex Ginzburg-Landau equation, the Gray-Scott model, and a three-component reaction diffusion model arising in gas-discharge phenomena.     

Cable guns as a plasma source in a plasma opening switch

The characteristics of a plasma generated by cable plasma guns have been studied by a laser interferometer. Cable plasma guns are frequently used as a plasma source in plasma opening switches. In our experiments, the plasma source consists of eight coaxial cable guns mounted on the outer electrode of concentric coaxial electrodes. The reproducibility of the gun in subsequent shots is found to be better than 10%, and the gun-to-gun difference is less than 15%. Assuming a symmetry of eight guns, the contour maps of the electron plasma density are plotted as functions of time. The plasma density becomes maximum near the gun nozzle and near the inner coaxial electrode. The plasma density is low in the area between the coaxial electrodes during the early time of the discharge. At a later time, the plasma fills the space between the two guns more uniformly. Still photographs of the plasma luminosity show a good correspondence with the plasma density plots which were taken 10 μs after the discharge initiation. The plasma gun system is designed for use in a 400-kA inductive voltage adder with the inductive energy storage system     

Studies of micro-brownian motion of a polymer chain by the fluorescence polarization method. II. Segmental motions in concentrated polymer solutions

The fluorescence polarization method has been used to study the micro-Brownian motion of a terminal segement of a polymer chain in concentrated solutions. A new apparatus for determining the fluorescence intensity and its polarization degree was designed. By using this apparatus, the rotational relaxation time 〈ρ〉 of the terminal segment of the fluorescent conjugates of polyacrylamide in aqueous polyacrylamide solutions was obtained as a function of polymer concentration from 0 to 65%, molecular weight of the conjugate from 3.5 × 10⁴ to 3 × 10⁵, and temperature from 10 to 30°C. The logarithm of 〈ρ〉 increased approximately linearly with increasing polymer concentration. This increase in 〈ρ〉, amounting to a factor of 20 times, was less marked than that in macroscopic viscosity. At concentrations less than 30%, 〈ρ〉 depended appreciably on the molecular weight of the conjugate.     

Die Dimensionen und Dipolmomente von Polypropylenglycol-Ketten

Ohne Zusammenfassung     

Inhibitory effects of bis(2-aminohexyl)disulfide and its analogues on polymorphonuclear leukocyte functions in vitro.

Water soluble analogues of the anti-inflammatory compound, bis(2-aminopropyl)disulfide dihydrochloride (compd. I) with a butyl (II), phenyl (III), benzyl (IV) or pyrrolidinyl group (V) instead of the methyl group were synthesized, and their effects on the functions of cells related to inflammation were studied in vitro. Compounds II, III and IV showed much higher inhibitory activity than compd. I on formyl Met-Leu-Phe (FMLP)-induced O2(-)-generation of polymorphonuclear leukocytes (PMNs) and platelet aggregation. Compound II showed the strongest activity among the compounds (IC50 values: 2.6 microM). The inhibition of O2(-)-generation of PMNs by compd. II was the most effective when FMLP was used as a stimulant rather than when phorbol myristate acetate, A-23187 and opsonized zymosan were used. However, compd. II was not an O2(-)-scavenger. Compounds II, III and IV significantly inhibited a series of activation processes in PMNs, chemotaxis, phagocytosis and lysosomal enzyme release at doses ranging from 10 to 100 microM. Under these doses, compds II, III and IV did not affect the histamine release from mast cells or the hemolysis of erythrocytes. These results strongly suggest that the anti-inflammatory action caused by compd. II and its analogues was at least partly due to inhibition of several functions of PMNs and platelets.     

Thermal degradation of polyesters by simultaneous TG-DTA/FT-IR analysis

A combination system of thermogravimetric/differential thermal analysis (TG-DTA) and Fourier-transform infrared absorption spectroscopy (FT-IR) was described. This simultaneous TG-DTA/FT-IR technique gave spectroscopic and weight loss information about the thermal degradation process of engineering polyesters; poly(ethylene terephthalate)(PET) and poly(butylene terephthalate)(PBT). The evolved gases from PET were benzoic acid, carbon dioxide and carbon monoxide, while those from PBT were terephthalic acid esters and benzoic acid esters.

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Zusammenfassung Es wird ein kombiniertes System aus TG-DTA und FT-IR beschrieben. Mit dieser simultanen TG-DTA/FT-IR-Technik wurden spektroskopische und Massenverlustangaben über die thermische Zersetzung technisch wichtiger Polyester, namentlich von Poly(ethylenterephthalat) (PET) und Poly(Butylenterephthalat) (PBT) ermittelt. Die aus PET freigesetzten Gase waren Benzoesäure, Kohlendioxid und Kohlenmonoxid, die aus PBT freigesetzten Gase hingegen Terephthalsäureester und Benzoesäureester.

     

Studies of the micro-brownian motion of a polymer chain by the fluorescence polarization method. III. Fluorescent conjugates of polyethyleneimine

Fluorescent conjugates of polyethyleneimine (PEI) were prepared by conjugation of fluorescent dyes, fluorescein isocyanate (FIC), and 1-dimethylaminonaphthalene-5-sulfonyl chloride (DNS), to PEI. The degree of polarization of the fluorescence was measured as a function of temperature and solvent viscosity on aqueous solutions of the conjugates and the data thus obtained were analyzed in terms of an equation of the Perrin type to calculate the mean relaxation time of the conjugate. The mean relaxation times obtained for the two types of the conjugates, which differ in the excited lifetime by a factor of about three, practically agree with one another and are about 2.5 X 10^?8 sec. The relaxation time of the DNS conjugate increases with increasing molecular weight of the conjugate from 2 X 10^?8 to 4 X 10^?8 sec. These values are much larger than those of the PAA conjugates reported in Part I of this series. The relaxation time of this order may correspond to that for the cooperative rotary motion of about ten monomeric residues on the PEI chain, that is, for the motion of an intermediate segment of the PEI molecule in solution. Finally, relaxation time–molecular weight relationships for various types of fluorescent conjugates are compared. It is suggested that these data may serve as a basis for elucidating the mode of motion of a given molecule in solution from the polarization data.     

Solution properties of cellulose tris(3,5-dimethyl-phenylcarbamate)

The dilute-solution behavior and liquid crystal formation of cellulose tris(3,5-dimethylphenylcarbamate) (CTDC) in 1-methyl-2-pyrrolidone (NMP) at 25°C are discussed by summarizing our recent studies, and its molecular characteristics are compared with those of cellulose tris(phenylcarbamate) (CTC) in the same solvent. The molecular weight dependences of optical anisotropy factor, radius of gyration, intrinsic viscosity ([η]), and isotropic-cholesteric phase boundary concentration for CTDC are explained consistently by current theories based on the wormlike chain. An analysis of the newly measured [η] for CTC shows that the backbone conformation and chain stiffness are substantially the same for the two cellulose derivatives in NMP. However, a distinct difference in optical anisotropy is found and briefly discussed in relation to the higher optical resolution capacity of CTDC than that of CTC in chromatographic separation of racemic compounds.