Nitric oxide density measurements at middle latitudes

Summary The measurements of nitric oxide density were made by the photoionization method at 30–90km in several rocket flights near Volgograd. TheseNO densities are well within the range of other measurements below 60km, but become rather high above 70km. The upper mesosphericNO densities estimated by two different methods from ionospheric data in Central Europe (50 °N) are rather high, as well. The appropriateNO densities in the upper mesosphere still seem to be an open question.     

On the problem of selective enhancement of barium in the atmospheres of BaII stars

High-resolution spectroscopy and standard LTE analysis of 31 barium and normal red giants (Astron. Astrophys. 283, 1994, p. 937) shows a selective enhancement of Ba (+0.5 dex) in two stars. HR 3845 and HD 130386, relative to the standard star Vir. We do not overinterpret these enhancements due to possible errors in the equivalent widths or in the atmospheric parameters. The non-LTE analysis of BaII in the atmospheres of red (barium) giants shows that the corrections for the non-LTE effects is relatively small, reaching a maximum of –0.16 dex, therefore, the enhancement of barium had apparently another nature.     

Changes of parameters of magnetic anisotropy of foliated rocks under pressure

Summary The changes of magnetic anisotropy under pressure were studied on a set of rocks with marked macroscopic stratification, collected from the Rjvíz borehole. The anisotropy parameters are relatively very stable under directional pressure, acting parallel with the rocks' bedding, and, on the contrary, significantly unstable under pressure acting perpendicular to the bedding. Systematically different magnitudes of stress sensitivity coefficients, , for parallel directional susceptibility were observed in both cases in the same types of rocks. The main cause is probably the different capability of transferring external stress to ferrimagnetics via the stratified non-magnetic matrix. With regard to magnetomechanical phenomena, therefore, a singel value of the stress sensitivity coefficient is insufficient to characterize rocks with a markedly anisotropic matrix.     

Lyrids 1994 observed by a forward scatter system

Radio observations of the Lyrid meteor shower obtained by a forward scatter radio system (Bologna-Lecce) in 1994 are analysed and discussed. The shower maximum appeared at solar longitude 31.0°(1950.0) and a distinct displacement between the maxima of the short-duration (< 1s) and long-duration ( 1s) echoes is observed. The shower has displayed a high activity, but no exceptional burst similar to that one observed in 1982, was recorded. It has been shown that the shower activity continues down to the smallest particle size of which existence in a meteoroid stream means their recent origin.     

Thermal stability of extended clusters in dravite: a combined EMP,SREF and FTIR study

A dravite from Yemen of near end-member composition was treated in air and hydrogen atmospheres at 600–900 °C to reveal changes in Mg and Al order over the octahedrally coordinated Y and Z sites, and to explore related changes in the characteristic vibrational bands in the principal (OH)-stretching frequency. Relevant information was obtained using electron microprobe analysis (EMPA), structural refinement (SREF) and polarized infrared (IR) single-crystal spectroscopy. Overall, the EMPA, SREF and IR data show that only minor changes occur during thermal treatment up to at least 800 °C, including variations in structural parameters, Mg–Al order–disorder and (OH)-stretching bands, indicating limited hydrogen loss. Untreated and treated dravite samples have very similar long-range and short-range atomic structures, which may be related to the occurrence of stable Al–Mg extended clusters around the O1 (=W) and O3 (=V) sites: ^W(F)–^Y(MgMgMg)–^V(OH)₃–^Z[AlAlAlAlAl(Al,Mg)]; ^W(OH)–^Y(MgMgAl)–^V(OH)₃–^Z[AlAlAlAlAl(Al,Mg)]; ^W(O^2–)–^Y(AlAlAl)–^V(OH)₃–^Z[AlAlAlAlAl(Al,Mg)]. These extended clusters remain stable to temperatures close to the observed start of decomposition (~900 °C).     

Spectroscopic and bond-topological investigation of interstitial volatiles in beryl from Slovakia

Nine beryl samples from Western Carpathians, Slovakia, were investigated by infrared and Raman spectroscopy and differential thermal analysis. Two types of water H₂O I and H₂O II were detected. Infrared spectroscopy proved the presence of water type I and II in the presence of alkali cations with several bands: (1) symmetric stretching vibration—ν₁; (2) antisymmetric stretching mode—ν₃; (3) bending vibration—ν₂. The presence of singly and doubly coordinated type II water (IIs and IId) was confirmed by single-crystal IR spectroscopy. From Raman spectra a band at 3606 cm^?1 was assigned to ν₁ of water type I and the range of 3597–3600 cm^?1 to water type II. The presence of doubly coordinating water indicates a relatively highly hydrated environment with the presence of alkali ions including Na as the dominant cation coordinated by H₂O II. CO₂ bands were detected only by single-crystal IR spectroscopy. Thermal analysis proved total water loss in the range of 1.4–2.0 wt% and three main dehydration events. Based on the study of bond-topological arrangements two molecules of H₂O IId are each bound with two H···O1 bonds and one Na–O_W bond with an angular distortion, and by releasing one H₂O molecule more stable H₂O IIs is produced. The H₂O I molecule is bound only by two equivalent hydrogen bonds. The H₂O IIs molecule with a Na–O_W bond strength of 0.28 vu and two H···O1 bonds of 0.14 vu without any forced angular distortion is the most stable of all.     

Isotope Geochemistry of Groundwater from Fractured Dolomite Aquifers in Central Slovenia

The hydrogeochemistry and isotope geochemistry of groundwater from 85 wells in fractured dolomite aquifers of Central Slovenia were investigated. This groundwater represents waters strongly influenced by chemical weathering of dolomite with an average of δ¹³C_CARB value of +2.2 ‰. The major groundwater geochemical composition is HCO₃ ^? > Ca²⁺ > Mg²⁺. Several differences in hydrogeochemical properties among the classes of dolomites were observed when they were divided based on their age and sedimentological properties, with a clear distinction of pure dolomites exhibiting high Mg²⁺/Ca²⁺ ratios and low Na⁺, K⁺ and Si values. Trace element and nutrient concentrations (SO₄ ^2?, NO₃ ^?) were low, implying that karstic and fractured dolomite aquifers are of good quality to be used as tap water. Groundwater was generally slightly oversaturated with respect to calcite and dolomite, and dissolved CO₂ was up to 46 times supersaturated relative to the atmosphere. The isotopic composition of oxygen (δ¹⁸O_H2O), hydrogen (δD_H2O) and tritium ranged from ?10.3 to ?8.4 ‰, from ?68.5 to ?52.7 ‰ and from 3.5 TU to 10.5 TU, respectively. δ¹⁸O and δD values fell between the GMWL (Global Meteoric Water Line) and the MMWL (Mediterranean Meteoric Water Line) and indicate recharge from precipitation with little evaporation. The tritium activity in groundwater suggests that groundwater is generally younger than 50 years. δ¹³C_DIC values ranged from ?14.6 to ?9.3 ‰ and indicated groundwater with a contribution of degraded organic matter/dissolved inorganic carbon in the aquifer. The mass balances for groundwater interacting with carbonate rocks suggested that carbonate dissolution contributes from 43.7 to 65.4 % and degradation of organic matter from 34.6 to 56.3 %.     

cD galaxies of apparent supergiant sizes due to the curvature of space

By combining two two-dimensional subspaces, closed into themselves due to curvature, it is possible to create a model of three-dimensional space of the same properties. If the Universe is a space of this type, its effect is that of a monstrous lens. Close objects are observed to diminish according to the normal law of perspective; however, the remote galaxies are seen to be very highly magnified.The apparent angular size² of a galaxy is more than the size¹ in flat space according to relation:² =¹ cosec , where is the angular distance from the observer to the galaxy. The diameter² d of a galaxy in curved space must be in the same relation to a diameter¹ d with no curvature of space:² d=¹ d cosec . The apparent angular size² and diameter² d are distorted shapes in consequence of an optical illusion caused by the spatial curvature.It is necessary to distribute the multitude of galaxies into two parts in accordance with their location on the close or reverse hemihypersphere of the Universe. The minimum of apparent angular size² of a galaxy of diameter¹ d is at the equatorial zone.The most likely candidates for location in the reverse hemi-hypersphere are cD's of apparent supergiant sizes due, probably, to the curvature of space. The existence of supergiant sizes of galaxies is the second indirect proof, besides superluminal velocities, that the Universe is closed into itself through curvature. The third indirect evidence, i.e., inductive confirmation of the same fact, is the superposition of galaxies which need not inevitably be a new alternative to the present theories of collisions, cannibalism, merger, etc.The fourth indirect proof of the positive curvature of the Universe is the occurrence of background radiation, because that must vanish in hyperbolic space irrespective of its origin. The gravitational lens effect acquires another theoretical form, as usual, in the case of remote galaxies, because it is impossible to distinguish between gravitator and lensing image.