Synthesis of Cu-containing Diopside through a One-Step Crystallization

The incorporation of copper into pyroxene structure was investigated through the melt quenching technique and one-step crystallization procedure. Two series of glasses have been studied, one set with Ca=Mg and another set with Ca>Mg in diopside formula Cux(Ca Mg)2-xSi2O6. The glasses were nucleated by TiO2, Cr2O3, or CaF2 additions as nucleating agents to variably control the phases produced. X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the obtained samples. The heat treatment studied at 700, 800, 900 and 1000 °C for 2 h produced green and dark green glasses based on Cu-containing diopside. Various crystalline wollastonite, cuprite, tenorite, cristobalite, quartz, and fluorite phases were developed with different ratios combined with diopside formation depending on the heat treatment and nucleating agents used. As the heat treatment increased in temperature, the crystallized fraction increased with the development of nano-aggregates and the observed reticulated textures confirmed a radical change in the euhedral crystals. This emphasizes that the Cu-containing diopside can be created by a facile one step process. These compositions may find some applications in biological and optical fields

From North Africa to Latin America and back: comparative findings and theoretical reflections

Taking the different case studies of the book together, one general observation stands out: Key agents of socioeconomic contention, including movements by organized labor and the unemployed that were important in the run-up to the uprisings and that saw their political opportunities open up in the immediate aftermath of the revolutions, have since been effectively marginalized as political actors. The concluding chapter reflects on the causes of this weakness of socioeconomic contention by identifying comparative insights that emerge from the contributions to this volume and by situating them in the context of broader comparative and theoretical debates on the relationship between social movements and political change. More specifically, the chapter first discusses Egypt’s and Tunisia’s post-revolutionary trajectories from a comparative perspective. Second, it discusses these comparative findings in the light of experiences in Latin America. Third, drawing again on comparative scholarship on Latin America, the chapter offers a theoretical interpretation of some of the main dynamics observed in Egypt and Tunisia based on the notion of a popular-sector incorporation crisis. Fourth and finally, the chapter concludes with general implications and an outlook

Securitizing the Muslim Brotherhood: state violence and authoritarianism in Egypt after the Arab Spring

Unprecedented levels of state violence against the Muslim Brotherhood, and the widespread acceptance of this violence by Egyptians following the July 2013 military coup, have been under-examined by scholars of both critical security studies and Middle East politics, reflecting implicit assumptions that state violence is unexceptional beyond Europe. This article explores how the deployment of such levels of violence was enabled by a securitization process in which the Egyptian military successfully appropriated popular opposition to Muslim Brotherhood rule, constructing the group as an existential threat to Egypt and justifying special measures against it. The article builds on existing critiques of the Eurocentrism of securitization theory, alongside the writings of Antonio Gramsci, to further refine its application to non-democratic contexts. In addition to revealing the exceptionalism of state violence against the Muslim Brotherhood and highlighting the important role of nominally non-state actors in constructing the Muslim Brotherhood as a threat to Egypt, the article also signals the role of securitization in re-establishing authoritarian rule in the wake of the 2011 uprising. Thus, we argue that securitization not only constitutes a break from ‘normal politics’ but may also be integral to the reconstitution of ‘normal politics’ following a period of transition

Crystallisation and substitutions of fluor-magnesio-richterite (Li,Na,K)2Mg6Si8O22F2 glasses

The effect of Li+ and K+ substitutions for Na + on the crystallisation of the fluor-magnesio-richterite, Na 2Mg6Si8O22F2, glasses was investigated. Transparent colourless glasses were obtained in all cases except when sodium was fully substituted by Li when cristobalite crystals where found in the melt. XRD measurements showed the presence of fluor-magnesio-richterite, proto-amphibole,fluorophlogopite, taeinolite, enstatite, forsterite, lithium disilicate and cristobalite in the samples crystallised in the 600-1000\ub0C temperature range. The coefficient of thermal expansion values of the glass-ceramic samples were in the range 98-116 710-7\ub0C -1 (20-500\ub0C) depending on the composition: fluoramphibole giving relatively higher values while enstatite and fluormica gave relatively lower values. The glass-ceramics had medium densities of 2.794-2.925 g/cm3. SEM images showed homogeneous microstructures of interlocked fibrous and flake-like crystals in a cryptocrystalline groundmass