Die Synthese von Hydrazinium(+2)-fluoromagnesat

Zusammenfassung Die Reaktion zwischen MgCO₃ und wässerigen Lösungen von Hydraziniumdifluorid und Flußsäure führt zum Hydraziniumfluoromagnesat. Diese Verbindung ist auch aus Magnesiumchlorid-und Hydraziniumdifluorid-Lösungen herstellbar. Es werden röntgenographische, IR-spektrographische und thermogravimetrische Untersuchungen dieser Verbindung angegeben.

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Hydrazinium(+2) fluoromagnesate is formed in the reaction between MgCO₃ and hydrazinium difluoride dissolved in hydrogen fluoride. The reaction of magnesium chloride and an aqueous solution of hydrazinium difluoride yields the same product. The results of X-ray diffraction studies, IR spectroscopical studies and thermogravimetrical investigation are given.

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Mit 3 Abbildungen     

Elemental composition of fine particulate matter (PM2.5) in Skopje,FYR of Macedonia

Aerosol samples were collected at an urban background site in Skopje, Former Yugoslavic Republic of Macedonia, during four measurement campaigns from December 2006 to October 2007. An impactor was used to collect particulate matter (PM_2.5) aerosol particles and the samples were analyzed for the concentrations of particulate mass, black carbon (BC), and 17 elements. The 12‐h average PM_2.5 concentrations varied in the range 10–140 µg m^?3 with the highest concentrations measured during wintertime pollution episodes and during the summer period. Pair‐wise correlations and crustal enrichment were studied and the data set was analyzed by factor analysis and positive matrix factorization. Major aerosol components were identified as mineral dust (main observed tracers Si, K, Ca, Ti, Fe, Sr, and Rb), combustion (BC, S, K, V, and Ni), traffic‐related aerosol (Pb and Zn), and secondary sulfate combined with mineral dust. Combustion sources dominated during wintertime and were likely due to heavy oil combustion, biomass burning, and other industrial activities within the city area. Mineral dust was observed throughout the year, but the concentrations peaked during the unusually hot and dry summer of 2007. It is concluded that Skopje suffers from serious air pollution due to central and residential heating, the transport sector, and industrial activities within the city, and contributions from mineral dust increase the PM_2.5 concentrations under dry periods. Topography and meteorological conditions aggravate the problems and make the air quality comparable with the conditions in other highly polluted cities in Southern Europe and worldwide. Copyright © 2011 John Wiley & Sons, Ltd.     

Wake effect in doped graphene due to moving external charge

We use the dielectric-response formalism to evaluate the induced density of charge carriers in supported graphene due to an external moving charged particle in terms of its velocity and distance from graphene for several equilibrium charge carrier densities due to graphene doping. We show that, when the particle speed exceeds a threshold value, an oscillatory wake effect develops in the induced charge density trailing the particle. Strong effects are observed in the wake pattern due to finite size of the graphene–substrate gap, as well as due to strong coupling effects, and plasmon damping of graphene?s π electrons.     

Backscattered electron spectra from graphite

The backscattered electron spectra from graphite sample were studied both experimentally and theoretically at impact energies between 500 and 5000 eV. The angle of the incident electron beam was 50° and the detection angle was 0° with respect to the surface normal, respectively. Monte Carlo (MC) simulations were performed based on the Classical Transport Theory (CTT) model to mimic the experimental spectra. In our simulations, both elastic and inelastic scattering of primary electrons and secondary electron emission from graphite are taken into account. There is found satisfactory agreement between measured and calculated electron spectra.     

Channeling of fast ions through the bent carbon nanotubes:The extended two-fluid hydrodynamic model

We investigate the interactions of charged particles with straight and bent single-walled carbon nanotubes(SWNTs)under channeling conditions in the presence of dynamic polarization of the valence electrons in carbon. This polarization is described by a cylindrical, two-fluid hydrodynamic model with the parameters taken from the recent modelling of several independent experiments on electron energy loss spectroscopy of carbon nano-structures. We use the hydrodynamic model to calculate the image potential for protons moving through four types of SWNTs at a speed of 3 atomic units. The image potential is then combined with the Doyle–Turner atomic potential to obtain the total potential in the bent carbon nanotubes.Using that potential, we also compute the spatial and angular distributions of protons channeled through the bent carbon nanotubes, and compare the results with the distributions obtained without taking into account the image potential.     

Similarity measures for sets of strings and application in chemical classification

This paper introduces new ideas for quantification of the similarity between chemical compounds. The method adopted makes use of similarity measures derived through comparison of two strings. The derived data on the similarity are then analyzed and applied in the identification of clusters in which the entities are more homogeneous and similar than those outside a cluster.     

Wake effect in interactions of dipolar molecules with doped graphene

We study the wake effect in the charge carrier density in free graphene induced by an electric dipole moving parallel to it by using the dynamic polarization function of graphene within the random phase approximation for its π electrons described as Dirac?s fermions. We show that, while the equilibrium doping density of graphene sets a length scale for the period of the wake via graphene?s Fermi wavenumber, qualitative properties of the wake are strongly affected by the speed of the dipole, its distance from graphene, and the dipole moment orientation.     

Proton channeling through long chiral carbon nanotubes: The rainbow route to equilibration

In this work we investigate the rainbows appearing in channeling of 1 GeV protons through the long (11,9) single-wall carbon nanotubes. The nanotube length is varied from 10 to 500 μm. The angular distributions of channeled protons are computed using the numerical solution of the proton equations of motion in the transverse plane and the Monte Carlo method. The rainbows are identified as the rings in the angular distributions, which correspond to the extrema of the proton deflection functions. Each rainbow is characterized by a sharp decrease of the proton yield on its large angle side. As the nanotube length increases, the number of rainbows increases and the average distance between them decreases in an easily predictable way. When the average distance between the rainbows becomes smaller than the resolution of the angular distribution, one cannot distinguish between the adjacent rainbows, and the angular distribution becomes equilibrated. We call this route to equilibration the rainbow route to equilibration. This work is a demonstration of how a simple one-dimensional bound dynamic system can exhibit a complex collective behavior.     

Rainbows in transmission of high energy protons through carbon nanotubes

We investigate theoretically the angular distribution and the rainbows in the case of 1 GeV protons transmitted through the 1 m long rope of (10, 10) single-wall carbon nanotubes. The angular distribution of transmitted protons is generated by the computer simulation method using the numerical solution of the proton equations of motion. Then, the rainbow lines corresponding to the angular distribution are determined. The analysis shows that the rainbow pattern defines the angular distribution – all its pronounced maxima except the maximum lying at the origin are the rainbow maxima. A possible application of the rainbow effect for characterization of nanotubes is suggested.     

Establishing the minimal index in a parametric family of bicyclic biquadratic fields

Let c ≥ 3 be a positive integer such that c, 4c + 1, c − 1 are square-free integers relatively prime in pairs. In this paper we find the minimal index and determine all elements with minimal index in the bicyclic biquadratic field K = ℚ(√(4c + 1)c, √(c − 1)c). The author was supported by the Ministry of Science, Education and Sports, Republic of Croatia, grant 037-0372781-2821.