Crystallization, microstructure and expansivity of spodumeneorthoclase glasses

The crystallization behaviour was investigated for some glasses, within the system spodumene-orthoclase, during different heat treatments by DTA, XRD and SEM. Kaolin and quartz sand were used as starting materials for the glass preparation and melting. The base glasses were stable through the heat treatments and did not show any crystallization propensity, whereas TiO2 additions catalyze the crystallization tendency in the glasses. The crystallization process involved the formation of β-spodumene and leceite in addition to the metastable high quartz, which disappeared at higher temperatures (>900 °C). Translucent glass-ceramies, containing uniform and nonuniform microstructures, were obtained in the ease of domination of high quartz and β-spodumene, respectively. Little difference in the coefficient of thermal expansion (CTE) was noted in the base glasses (64 to 66 ∙ 10^-7 at 20 to 500 °C) and the TiOs doped glasses (60 to 69 ∙ 10^-7 K^-1 at 20 to 500 °C). Change in CTE in the TiOs doped glass ceramie samples from 37 to 69 ∙ 10^-7 at 20 to 300 °C depends mainly on the content of crystallized β-spodumene in addition to the residual glass. However, an increase in β-spodumene content in the crystallized glass-ceramies lowers the value of CTE and vice versa

al-Manar al-Jadid Changes in the Contemporary Islamist Discourse

The periodical al-Manar al-Jadid was first published in January 1998 in Cairo. In the words of its editor-inchief, Gamal Sultan, its aim is: 'To establish a civilized and authentic intellectual forum, to combat the waves of westernization, arbitrariness and opportunism in the Islamic world.' The initiators of the publication include such prominent Islamists as Muhammad cImara, Tariq al-Bishri, Yusuf Qaradawi, and Rashid al-Ghanushi, as well as activists of the younger generation, like kamal habib, a leading member of the Jihad Group in the 1980s. The new periodical is obviously linked to the famous al-Manar issued in 1898 under the patronage of Rashid Rida

Arab Intellectuals, Usama bin Laden and the West

The printed Arabic media offer hardly any critical review of the social and political settings in the Arab world that may help to explain the emergence of violent Islamist groups. Standard newspaper articles and comments on the post-September 11 events vary from elaborations of the marked inconsistencies in US foreign policies to the popular conspiracy theories in which 'international Zionism' is blown up to mythical proportions. A few intellectuals, however, opt for a more open and frank approach to the issues involved, including some who had been accused in the past of endorsing militant Islamism

QuEChERS Method Followed by Solid Phase Extraction Method for Gas Chromatographic-Mass Spectrometric Determination of Polycyclic Aromatic Hydrocarbons in Fish

A gas chromatography equipped with mass spectrometer (GCMS) method was developed and validated for determination of 16 polycyclic aromatic hydrocarbons (PAHs) in fish using modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and solid phase extraction for sample cleanup to remove most of the coextract combined with GCMS for determination of low concentration of selected group of PAHs in homogenized fish samples. PAHs were separated on a GCMS with HP-5ms Ultra Inert GC Column (30 m, 0.25 mm, and 0.25 µm). Mean recovery ranged from 56 to 115%. The extraction efficiency was consistent over the entire range where indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene showed recovery (65, 69%), respectively, at 2 µg/kg. No significant dispersion of results was observed for the other remaining PAHs and recovery did not differ substantially, and at the lowest and the highest concentrations mean recovery and RSD% showed that most of PAHs were between 70% and 120% with RSD less than 10%. The measurement uncertainty is expressed as expanded uncertainty and in terms of relative standard deviation (at 95% confidence level) is ±12%. This method is suitable for laboratories engaged daily in routine analysis of a large number of samples

Sintered Iron-Rich Glass-Ceramics and Foams Obtained in Air and Argon

The subsequent synthesis of sintered self-glazed glass-ceramics and/or glass-ceramic foams using metallurgical slag is the topic under discussion. The observed intensive sample expansion can be considered as an autocatalytic process related to the oxygen release due to thermal reduction of Fe2O3 and MnO2 present in the slag. The sintering of the samples is studied by optical dilatometry and the foaming process by hot-stage microscopy, while the structure of the final materials is revealed by 3-D computed tomography and SEM. The phase composition of the glass-ceramic foams is analyzed by XRD. The species are characterized by moderate crystallinity, 80–85 vol.% porosity and fire resistance above 1000°C. The innovative point of this study is the synthesis in argon of sintered glass-ceramic materials where reduction is inhibited, together with a double-stage foam formation in air and argon, leading to lower working temperatures and better material characteristics

Effect of Cr2O3, ZrO2 and LiF on nucleation and crystallization of nepheline syenite-dolomite glass-ceramic compositions

Inexpensive nepheline-pyroxene glass-ceramics of superior mechanical, and thermal properties could be easily prepared from nepheline syenite and dolomite rock mixture by using the conventional glass preparation and heat treatment methods. The parent glass composition, to yield ≈35 % nepheline ss (solid solution) and 65 % diopside ss, was formulated by a modified chemico-mineralogical calculation method after CIPW norm. The effect of the nucleating agents Cr2O3, ZrO2 and LiF on the mechanisms of nucleation and crystallization of these phases were determined by DTA, XRD, as well as optical and electron microscopy. In the absence of these nueleators, crystallization was difficult and semi-crystalline coarse microstructure of diopsidic ss was obtained. LiF showed maximum effect on crystal growth rates, while sufficient nucleation density for glass-ceramic of good quality was achieved by adding Cr2O3 even in the amount as small as 0.5 wt%. Both Cr2O3- and ZrO2-containing samples hindered the crystallization of nepheline but greatly stimulated the epitactic formation of diopside ss of holocrystalline microstructures. LiF-containing samples stimulated the crystallization of the framework silicates, nepheline ss and carnegieite, which progressively increased with the LiF concentration. The thermal expansion coefficient and Vickers hardness of the obtained glass-ceramic reached values of 9.0 × 10^-6 K-1 (20 to 300 °C) and (950 × 10^7 ± 25) N/m2, respectively

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

Bullets over ballots: Islamist groups, the state and electoral violence in Egypt and Morocco

This article is concerned with state-sponsored electoral violence in liberalized autocracies. The first section of the paper identifies a number of variables that can help explain the decision calculus of authoritarian incumbents to deploy force against strong electoral challengers. The second section then examines these propositions with reference to Egypt and Morocco. Drawing on recent parliamentary elections in both countries the article questions why, despite facing the challenge of political Islam, the two regimes differed so markedly in their willingness to manipulate the polls by recourse to violence. Whilst the Egyptian authorities decided to abrogate all pretence of peaceful elections in favour of violent repression against the Muslim Brotherhood candidates and sympathizers, no such tactics were deployed by the ruling elite in Morocco. We suggest that three principal factors influenced the regimes' response to this electoral challenge: (1) the centrality of the elected institution to authoritarian survival; (2) the availability of alternative electioneering tools; and (3) the anticipated response of the international community. The article concludes by suggesting that in order to understand better when and how states deploy violence in elections, we need to focus on a more complex set of factors rather than simply on the electoral potency of key opposition challengers or the authoritarian nature of the state

Cancer Cells Treated by Clusters of Copper Oxide Doped Calcium Silicate

Purpose: Different compositions of copper oxide (CuO)-doped calcium silicate clusters wereused to treat the cancer cells.Methods: The influence of CuO content on the morphology, drug delivering ability,physicochemical properties and cytotoxicity was investigated.Results: The microcrystalline structure revealed the decrement of the size from (20-36 nm) to(5-7 nm) depending on the copper content percentages. Drug delivering ability of doxycyclinehyclate (Dox) was down regulated from 58% to 28%in the presence of the CuO. The inclusionof CuO and Dox didn’t show any remarkable changes on the physicochemical properties of theCuO-doped calcium silicate nanoparticles.Conclusion: The CuO-doped calcium silicate sample (5 weight %) exhibited great cytotoxicityagainst the tested cell lines compared to the CuO-free sample. CuO-doped materials displayedsignificant anticancer effect; this sheds light on its implication in the treatment of cancer

The UfM and the Middle East 'Peace Process': An Unhappy Symbiosis

This contribution explores differing theories on how the failure of the ‘peace process’ featured in the design and goals of the UfM, drawing on lessons from the period when the EMP was pursued in parallel with the peace process. In each case, institutional overlaps are identified, as well as commonalities in the approaches of the actors to both pursuits. Crucially, however, the persistence and intensification of the Arab–Israeli conflict, in combination with the shift from multilateralism to bilateralism embodied in the UfM, has politicized the latter at the expense of the functionalist aspirations of its architects