Dilute solution properties of polylaurolactam

For a number of fractions and unfractionated samples of polylaurolactam, molecular weights ($\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{= 1 × 10}{}^4\text{?12·5 × 10}{}^4$) were measured by the light-scattering method in a mixed solvent of m-cresol with 60 vol. % 2,2,3,3-tetrafluoropropanol; intrinsic viscosities were determined in m-cresol and 96% H₂SO₄, and the constants of the Mark-Houwink equation were calculated. The calculated values of the characteristic ratio of unperturbed dimensions (virtually identical for m-cresol and 96% H₂SO₄) were compared with the respective values for polypyrrolidone and polycaprolactam. It was found that the higher frequency of the CONH-groups reduces the rigidity of the polyamide chain.     

Iodine photodissociation laser system Perun II

A construction and exploitation of a medium size iodine photodissociation laser system Perun II is reported. This laser produced pulses of infrared light (=1.315m) up to 50 J in energy and 300 ps in duration. The diameter of the beam is 82 mm. The beam divergence is about 4×10^–4 rad. The laser beam can be focused in a focal spot of a power density exceeding 10¹⁴ W/cm². The resuls of measurements of basic plasma parameters on an Al foil target are also presented. A recent improvement of the system includes a conversion to the second harmonic by a DKDP crystal.Presented at bilateral international seminar of High Temperature Laser Plasma and High Gain Iodine Lasers held on 4 July 1991 in the Inst. of Physics, Czechosl. Acad. Sci., in Prague (organized by Division of Optics of the Inst. of Physics, Czechosl. Acad. Sci., and Physical Section (Plasma Division) of the Union of Czech Mathematicians and Physicists.     

Composite ion exchanger with ammonium molybdophosphate and its properties

An organic binding polymer based on polyacrylonitrile (PAN) was used for the preparation of the composite exchanger containing ammonium molybdophosphate (AMP) as the active component. Due to the improvement of granulometric properties of powdered AMP with a binding polymer, an exchanger suitable for the application in column operations was prepared. Study of the properties of the exchanger AMP-PAN proved that kinetics of cesium sorption, capacity of the exchanger for cesium and desorption of cesium are not influenced by the binding polymer. The composite exchanger AMP-PAN described is therefore suitable for the selective separation and concentration of cesium and purification of radioactive wastes from¹³⁷Cs.     

Polymerization of methylmethacrylate in presence of tetramethylthiuramdisulphide

The effect of TMTD on the polymerization of methyl methacrylate was studied. The plot of $\text{R}{}_{\mathrm{P}}\text{vs [TMTD]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ shows a maximum ascribed to participation of TMTD-radicals in cross (P′ + RS′) and mutual-termination (RS′ + RS′). The total polymerization rate is then well expressed by a derived relation. Study of the influence of TMTD on the molecular weight of polymethylmethacrylate allows characterization of the transfer process.     

Field and temperature dependence of magnetization of U3P4

Conclusions We conclude that the occurrence of a maximum in the magnetization versus temperature curve observed under certain circumstances on U₃P₄ is not connected with its intrinsic magnetic structure, but substantially depends on the form in which the material is studied (polycrystalline powder, single crystal, single crystal powders with various dimensions of grains). This phenomenon seems to be affected by quenching of the state from the region of low anisotropy at higher temperature in the small particles with a strong tendency to single domain behaviour and thus it may be a consequence of rotation magnetization process in the fields relatively small for U₃P₄. The assertion about transitions between magnetic ordering, sometimes proposed in the literature on the basis of observed anomalies in the temperature course of magnetization without simultaneous confirmation by neutron diffraction, should be accepted with some reservation, especially in the case of simple uranium compounds. However, another situation arises for pseudobinary alloys of ferro- and antiferromagnetic components (e.g. UP_0·75S_0·25) where such transitions were confirmed both by magnetic methods and by neutron diffraction studies [13].The authors would like to express their thanks to Ing. A.Meovský for careful preparation of samples.     

Excitation of the Characteristic K Series Radiation,Coherent and Incoherent Scatter of Low Energy Gamma Rays

On the basis of a simplified mathematical model there is calculated the probability of a photon of characteristic K series radiation excited by a photon of low energy gamma radiation hitting the detector. There are also included the probabilities for coherently and incoherently scattered primary radiation considering electron binding energies.     

Energy independent number of clusters and multiplicity distribution at Collider and beyond

Multiplicity distributions up to the Collider energies could be described by various two-parameter compounded distributions having in common Poisson distributed number of clusters. Among them the logarithmic distribution for hadronization via decaying clusters leads to energyindependent number of clusters above the ISR energies, replacing the previous KNO-scaling.Dedicated to the 30th anniversary of the Joint Institute for Nuclear Research.