On the Reflectivity of Materials for Radio Telescope and Space Antenna Applications: Antenna reflector loss needs to be known for many specific antenna applications

Systeem voorwaarden kunnen het gebruik van reflector-materialen voorschrijven, ook al zijn de materialen niet altijd "perfect elektrisch geleidend". Dat betekent dat je de materiaal eigenschappen goed moet kennen, dus moet je het meten. Een bepaald reflectie verlies kan aanvaardbaar zijn voor de ene toepassing, maar niet voor de andere toepassing. Instrument- of radiometer-antennes vereisen een laag verlies, terwijl het soms minder kritisch kan zijn voor telecommunicatie antennes. We hebben materialen onderzocht die minder gebruikelijk zijn, maar soms noodzakelijk zijn in bepaalde ruimtevaart toepassingen. Zo ook materiaal gebaseerd op geelectroformeerd nickel voor toepassing in de telescoop antennes voor ALMA. Een gevoelige open resonator is hiervoor gebruikt. De verzamelde data heeft inzicht gegeven voor de toepassingen en ook voor de verlies-eigenschappen voor de besproken toepassingen. Het heeft ook geleid tot een paar niet al te moeilijke modellen, welke overeenstemmen met de metingen

The effect of the nonplanarity of heterocyclic analogues of fluorene with the phosphorus atom on spin-orbit interactions

The transition dipole moments P00s for the transitions from the sublevels s = z, y, and x of the triplet electronic states 3A″, which are caused by intramolecular spin-orbit (SO) interactions, are calculated. The calculation is carried out for molecules of heterocyclic analogues of fluorene containing phosphorus and nitrogen (namely, the groups P-H, P-C6H5, and N-H). The influence that the planar and nonplanar models of the molecules, as well as the substituents -C6H5 and -H at the heteroatom (HA), exert on the values of (P00s)2 and on the directions of the corresponding vectors is considered. The values of the component kSO ∼ ∑s (P00s)2 of the radiative deactivation rate constant of the T1 state are calculated. It is ascertained that, in the series of molecules with HA = N, O, P, and S, both the calculated values of kso and those experimentally determined from an analysis of the intensity distribution in fine-structure phosphorescence spectra vary little, whereas the constant of the SO coupling in the heteroatom ςHA increases substantially along this series. The reason for the weak influence of ςHA on values of k so - common for both planar and nonplanar molecules - is found. ©2004 MAIK "Nauka/Interperiodica"

The effect of the nonplanarity of heterocyclic analogues of fluorene with the phosphorus atom on spin-orbit interactions

The transition dipole moments P00s for the transitions from the sublevels s = z, y, and x of the triplet electronic states 3A″, which are caused by intramolecular spin-orbit (SO) interactions, are calculated. The calculation is carried out for molecules of heterocyclic analogues of fluorene containing phosphorus and nitrogen (namely, the groups P-H, P-C6H5, and N-H). The influence that the planar and nonplanar models of the molecules, as well as the substituents -C6H5 and -H at the heteroatom (HA), exert on the values of (P00s)2 and on the directions of the corresponding vectors is considered. The values of the component kSO ∼ ∑s (P00s)2 of the radiative deactivation rate constant of the T1 state are calculated. It is ascertained that, in the series of molecules with HA = N, O, P, and S, both the calculated values of kso and those experimentally determined from an analysis of the intensity distribution in fine-structure phosphorescence spectra vary little, whereas the constant of the SO coupling in the heteroatom ςHA increases substantially along this series. The reason for the weak influence of ςHA on values of k so - common for both planar and nonplanar molecules - is found. ©2004 MAIK "Nauka/Interperiodica"

Study of the Catalytic Pyrolysis of Poly(vinyl chloride) and Poly(vinyl chloride)-Based Materials over LaVOх Nanostructured Systems

Abstract: This study is focused on the catalytic pyrolysis of poly(vinyl chloride) over LaVOх nanostructured systems. LaVOх-type catalysts are synthesized by the solid-phase high-temperature interaction of the stoichiometric amounts of V2O5 and La2O3 and investigated by various physicochemical methods. The study of poly(vinyl chloride) noncatalytic pyrolysis under atmospheric pressure makes it possible to determine the onset temperature of the intense degradation and the optimum temperature of the pyrolysis of this material. It is shown that the catalytic pyrolysis with the use of LaVOх-type catalysts changes the qualitative and quantitative composition of gaseous fraction products so that the proportion of light olefins as the target product is increased while the yield of hydrogen chloride is suppressed by 50% compared with noncatalytic pyrolysis. © 2020, Pleiades Publishing, Ltd

Resonator method for studying dielectric characteristics of caustobiolithes

For the sub-THz range, a method for studying the electrodynamic characteristics of organic materials - caustobiolithes-is developed on the basis of a resonator spectrometer. In the frequency range 110 ÷ 260 GHz, the dielectric parameters (refractive index n and tand) of peat powders after its microwave processing in the process of «soft» pyrolysis, as well as core sections of oil-containing rock, were studied. The influence of natural humidity on the dielectric parameters of the samples is considered. The reasons for the spread of measurement results, which is observed in these materials and is their specific feature, are discussed

Evolution of the Central Indian tectonic zone: Geochemical and isotope-geochronological data

In the framework of the Russian-Indian joint research projects geochemical and geochronological study of granitoid rocks across the Central Indian Tectonic Zone has been carried out. Geochronological data suggest that the Central Indian Tectonic Zone is composed primarily of Proterozoic rocks, formed as a result of several stages of granitoid magmatism: at 2.43, 2.34-2.31, 1.73-1.72 and 1.53-1.51 Ga. Metamorphic transformations reflected by Sm–Nd and Rb–Sr systems of rocks and minerals occurred 1.37-1.1 Ga ago that allows comparing the final processes in the Central Indian Tectonic Zone with the Grenville orogeny and it can be used for the reconstruction of Rodini