Effect of the partial replacement of CaH2 with CaF2 in the Mixed System CaH2 + MgB2

In this work the effect of a partial replacement of CaH2 with CaF2 on the sorption properties of the system CaH2 + MgB2 has been studied. The first five hydrogen absorption and four desorption reactions of the CaH2 + MgB2 and 3CaH2 + CaF2 + 4MgB2 systems were investigated by means of volumetric measurements, high-pressure differential scanning calorimetric technique (HP-DSC), 11B and 19F MAS NMR spectroscopy, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD). It was observed that already during the mixing of the reactants formation of a nonstoichiometric CaF2-xHx solid solution takes place. Formation of the CaF2-xHx solid solution sensibly affects the overall hydrogen sorption reactions of the system CaH2 + MgB2

Hydrogen storage systems from waste Mg alloys

The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH 2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes

A computational study on outliers in world music

The comparative analysis of world music cultures has been the focus of several ethnomusicological studies in the last century. With the advances of Music Information Retrieval and the increased accessibility of sound archives, large-scale analysis of world music with computational tools is today feasible. We investigate music similarity in a corpus of 8200 recordings of folk and traditional music from 137 countries around the world. In particular, we aim to identify music recordings that are most distinct compared to the rest of our corpus. We refer to these recordings as ‘outliers’. We use signal processing tools to extract music information from audio recordings, data mining to quantify similarity and detect outliers, and spatial statistics to account for geographical correlation. Our findings suggest that Botswana is the country with the most distinct recordings in the corpus and China is the country with the most distinct recordings when considering spatial correlation. Our analysis includes a comparison of musical attributes and styles that contribute to the ‘uniqueness’ of the music of each country

Porównanie efektywności uprawy jęczmienia ozimego i jarego w stanowisku po ziemniaku

W pracy podjęto próbę określenia i porównania efektywności ekonomicznej uprawy jęczmienia ozimego i jarego w rejonie Ostródy (województwo warmińsko- mazurskie). Analizę oparto na wynikach wieloletniego doświadczenia płodozmianowego, z uwzględnieniem poziomu cen zbóż z II kwartału 2003 r. Zysk z jednostki powierzchni był o 88,7% wyższy w przypadku jęczmienia ozimego niż jarego. Wskaźnik opłacalności produkcji jęczmienia ozimego wynosił 1,70, a jarego – 1,30. Nieco mniejsze dysproporcje charakteryzowały wskaźnik efektywności energetycznej. Parametr ten obliczony dla jęczmienia ozimego wynosił 2,94, natomiast dla jęczmienia jarego – 2,37. Analiza porównawcza produkcji jęczmienia ozimego i jarego w stanowisku po ziemniaku wskazuje na wyższą efektywność energetyczną oraz korzystniejsze wyniki ekonomiczne uzyskane z uprawy jęczmienia ozimego niż jarego.This paper attempts at defining and comparing winter and spring barley economic effectiveness. The analysis was based on long-term crop rotation experiment and grain prices in the second quarter of 2003. The profits obtained per area unit were 88.7% higher for winter barley. The profitability ratio for winter barley reached 1.70; and for spring barley – 1.3. Smaller differences were found for energy efficiency index; 2.94 for winter barley and 2.37 for spring barley. The comparative analysis of winter and spring barley production on the stand after potato shows a higher energy efficiency and more favourable economic results for winter barley

First Direct Study of the Ammonolysis Reaction in the Most Common Alkaline and Alkaline Earth Metal Hydrides by in Situ SR-PXD

We report on the first in situ synchrotron radiation powder X-ray diffraction study (SR-PXD) of the ammonolysis reaction of selected alkaline and alkaline earth metal hydrides (i.e., LiH, NaH, KH, MgH2, and CaH2). The investigation was performed using an in situ SR-PXD pressure cell at an initial NH3 pressure of 6.5 bar in a range of temperature between room temperature (RT) and 350 degrees C. The results of this work give new important insights into the formation of metal amides and imides starting from the corresponding metal hydrides. LiH was observed to react with NH3 to form LiNH2 already at RT, and then it decomposes into Li2NH at 310 degrees C through the formation of nonstoichiometric intermediates of the Li1+-xNH2-x form. The formation of NaNH2 takes place nearly at RT (28 degrees C), and it melts at 180 degrees C. As for LiH, KH reacts with NH3 at RT to surprisingly form, what it seems to be, cubic KNH2. However, we believe this phase to be a solid solution of KH in KNH2. At high temperature, the possible formation of several solid solutions of K(NH2)(1-y)H-y with defined composition is also observed. The formation of Mg(NH2)(2) was observed to starts at around 220 degrees C, from the interaction beta-MgH2 and NH3. At 350 degrees C, when all beta-MgH2 is consumed, the formation of Mg(NH2)(2) stops and MgNH is formed by the reaction between beta-MgH2 and NH3. Our results indicate that the formation of the beta-MgH2 is a key step in the synthesis of Mg(NH2)(2) at low temperature (e.g., via ball milling technique). CaH2 was observed to react with NH3 at around 140 degrees C to form CaNH. At higher temperature the appearance of new reflections of possible Ca1+xNH phases, with the same crystalline structure of CaNH but with a smaller cell parameter was observed

Effect of the Partial Replacement of CaH2 with CaF2 in the Mixed System CaH2 + MgB2

In this work the effect of a partial replacement of CaH2 with CaF2 on the sorption properties of the system CaH2 + MgB2 has been studied. The first five hydrogen absorption and four desorption reactions of the CaH2 + MgB2 and 3CaH(2) + CaF2 + 4MgB(2) systems were investigated by means of volumetric measurements, high-pressure differential scanning calorimetric technique (HP-DSC), B-11 and 19F MAS NMR spectroscopy, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD). It was observed that already during the mixing of the reactants formation of a nonstoichiometric CaF2-xHx solid solution takes place. Formation of the CaF2-xHx solid solution sensibly affects the overall hydrogen sorption reactions of the system CaH2 + MgB2

Hydrogen storage systems from waste Mg alloys

The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH 2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes. © 2014 Elsevier B.V. All rights reserved