A New Setting for Polynomial Continuous-Time Systems, and a Realization Theorem

The paper deals with polynomial continuous time systems on algebraicmanifolds. The main result states that a nonlinear system maybe regularly immersed into a polynomial algebraically observablesystem ifi its observation algebra is finitely generated andregular. We also indicate some perspectives for future workin this direction.     

A Ramsey-Sperner theorem

Letn≥k≥1 be integers and letf(n, k) be the smallest integer for which the following holds: If ℱ is a family of subsets of ann-setX with |ℱ|<f(n,k) then for everyk-coloring ofX there existA B ∈ ℱ,A∈B, A⊂B such thatB-A is monochromatic. Here it is proven that for a fixedk there exist constantsc _k andd _k such that and ask→∞. The proofs of both the lower and the upper bounds use probabilistic methods.     

Magnetic structures of R(Cu,Ni)2 compounds (R = heavy rare earth) studied by neutron diffraction

Magnetics structures of powdered orthorhombic R(Cu, Ni)₂ compounds (R = heavy rare earth) determined by neutron diffraction are described. The influence of magnetocrystalline anisotropy and exchange interactions on the type of magnetic ordering is discussed.Dedicated to Academician Vladimír Hajko on the occasion of his 65th brithday.We would like to express our thanks to Professor P. Luká for continual interest and encouragement and to . Zajac and V. Sechovský for many fruitfull discussions.     

A study of fast neutron production in p20Ne and pp interactions at 300 GeV/c

Data on the multiplicity, momentum and angular spectra of fastp _n1 GeV/c) neutrons produced in inelastic interactions of protons with neon nuclei and protons at 300 GeV/c are presented. The experimental results obtained for p²⁰Ne interactions are compared with predictions of the additive quark model in which the intranuclear cascading of slow particles is taken into account.We thank V. G. Grishin and R. J. Loveless for valuable discussions.     

High-field recombination electroluminescence in vacuum-deposited anthracene and doped anthracene films

The electroluminescence (EL) study of anthracene and tetracene-doped anthracene films deposited by a vacuum evaporation onto a substrate at temperatureT ₀=–60 °C is reported. Such films show high resistence to electrical breakdown so that their EL behaviour at high electric fields up to above 10⁶ V/cm could be investigated. The high-field EL is interpreted in terms of electron-hole recombination mechanisms with creation of emitting singlet excitons; the electron and hole concentration being limited by injection at metal contacts and by field-independent carrier velocities. The theoretical expression for current density follows the experimental data for fields above 4×10⁵ V/cm at room temperature and the EL intensity is predicted to be a power function of the measured current. It is suggested that in pure anthracene layers the power is determined by the contact injection conditions, i.e. by barrier heights and the effective masses of holes and electrons. In the doped films a guest molecules-induced energy trap distribution leads to a decrease of the power as confirmed by the experimental plots of the host EL intensity versus current density.The work supported in part by the Polish Academy of Sciences under Program MR.I.9     

Shape memory effect in antiferromagnetic γ - manganese alloys

Conclusion Thus, the crystallography and the character of antiferromagnetic transformations in manganese alloys determine several specific features of the manifestation of the shape memory effect in these materials. Among these features are: clearer manifestation of reversible deformation, even in the case of small initial strains; a broad temperature range associated with deformation; the practically hysteresis-free character of the reversible deformation in polycrystalline materials; the existence of alternating reversible deformation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 104–117, May, 1985.     

Adsorptive stripping voltammetric analysis of 2,4,6-tri(2′pyridyl)-1,3,5-triazine at a mercury electrode

The redox behaviour of adsorbed species of 2,4,6-tri(2-pyridyl)-1,3-5-triazine (TPTZ) at the surface of a mercury electrode was examined using cycling voltammetry. Based on the adsorption and accumulation of TPTZ at the charged mercury surface cathodic adsorptive stripping voltammetry (CSV) is applied for the trace determination of TPTZ using a differential pulse (DP) technique. Experimental and operational parameters for the quantitative analysis of TPTZ are optimized and the detection limit was found to be 3×10^–9 mol/l. The effect of some interferences, e.g. organic compounds, cations and anions, are investigated.     

Investigation of mercury speciation in lichens.

Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points.     

Structure and reactivity of 3- and 4-[(4′-chlorophenyl)sulfamoyl]-1-diazoalkan-2-ones

Conclusions Under the conditions of the acidic cyclization reaction of homologous 3- and 4-[(4-chlorophenyl)sulfamoyl]-1-diazoalkan-2-ones, the formation of the five-membered heterocycle, a pyrrolidin-3-one derivative, is more convenient than the formation of the four-membered heterocycle- an azetidin-3-one derivative. These results are in agreement with the differences in conformations of diazoalkane molecules in the crystalline state.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 134–138, January, 1986.