Authors:F. Gomez, P. Vast, Ph. Llewellyn, and F. Rouquerol
We used CRTA for the study of both the elaboration and characterization of several polyphosphate glasses. We show that controlled transformation rate thermal analysis is able to remove a systematic error present in classical thermal analysis, in the study of the precursor of the phosphate glass. We show too that in CRTA, water release in the phosphate glasses can take place by diffusion phenomena at low temperature and that it is not due to the crystallization. These two examples illustrate some interests of this inverse method in the study of the decomposition of inorganic compounds with water release.
Thermoanalytical techniques, especially temperature-programmed reduction (TPR), were employed for the characterization of
oxidic precursors of molybdenum-based catalysts, sulfides derived from them, and three thiomolybdate compounds, employed as
models or precursors of hydrodesulfurization atalysts. Correlations were found between TPR data and the presence of single
and mixed oxides of Mo and Ni, Co or Fe, as demonstrated by XRD. The same phases and the thiomolybdates were shown to be present
in supported catalytic precursors. Differences between the reducibilities of the mixed oxides of Ni-Mo, Co-Mo and Fe-Mo are
easily appreciated from TPR, including those of the α- and Β- polymorphic modifications of NiMoO4.
The characterization of a few Mexican clays with chemical treatmentfor possible application as catalysers is shown. The natural clays are treatedwith H2 SO4 , HF, F3 CSO3 H, ClSO3 H, HClO4 and their behavior in reactions with some alcoholswas recorded. The analysis were made before and after using the clays as catalysers.The clays were characterized by Mössbauer spectroscopy, X-ray diffraction,X-ray fluorescence analysis, and differential thermo analysis. The predominantmineral species are: montmorillonite, christobalite and quartz. The main elementsare: Si, Al, Fe, Ca, K, etc. The Mössbauer results show mainly a paramagneticdoublet of Fe3+ . The clays behave similarly as described in theliterature.
, aluminic or silicic , should predominate, depending on whether the effects deriving from their Al 2 O 3 r− content prevail or otherwise over the effects of their SiO 2 r− content. Nonetheless, in the best of cases, such characterizations take at least
Authors:Robert Vajtai, Sujit K. Biswas, Binqing Wei, Gouwen Meng, Yung Joon Jung, and Pulickel M. Ajayan
Single and multiwalled carbon nanotubes have attracted significant interest due to their one-dimensional structure and unique electrical and mechanical properties. Among the wide variety of their potential applications most importantly they offer potential to serve as building blocks for future electronic device architectures [1, 2, 3, 4, 5, 6]. Carbon nanotubes may serve as active or passive electronic elements; and as passive elements they may serve as interconnects both on short and long ranges [7, 8]. The most essential prerequisite for realizing CNT architectures is to be able to grow nanotubes at controlled sites, in predetermined orientations and to form interconnections. Significant progresses in growing aligned carbon nanotube films have been made recently with a combined approach of the floating catalyst method using pre-patterned templates and chemical vapor deposition (CVD) [9, 10, 11, 12]. Recently we summarized our work on growing architectures of carbon nanotubes, which might be integrated into microelectronic circuits . While the predefined growth of the above mentioned large nanotube structures is important and receives a lot of attention characterization of the product also deserves similarly high attention being a key for future applications and giving the real importance and purpose of the growth efforts. In this paper, we report some of our works, which are directed towards electrical tests on CNTs, namely high current carrying capacity; vertically organized multiwalled nanotubes showing the possible usage of highly ordered and well-shaped tubes; and characterization of singlewalled nanotube junctions.
In this study, 15 bovine viral diarrhoea viruses (BVDV) isolated from the field in Turkey were characterised for their biotype, cloned and eventually analysed for their epitopic composition in terms of glycoprotein E2. Immunoplaque assay, plaque assay, limiting dilution and streptavidin-biotin-peroxidase techniques were used for biotype characterisation, cloning of cytopathic (cp) and noncytopathic (ncp) biotypes and epitope analysis, respectively. While 14 out of 15 BVDV isolates were distinguished as ncp biotype, 1 isolate was found to be containing both biotypes (cp + ncp). According to the reactivity patterns of isolates with 15 monoclonal antibodies, 4 different antigenic groups could be formed. There were no antigenic differences between the isolates derived from the same animal with various time intervals. On the other hand, biotype clones isolated from the same animal exhibited difference in one epitope. This is the first study describing antigenic characterisation of BVDV field isolates in Turkey.
Authors:J. Lawry, A. Ray, D. Klimesch, P. Thomas, J.-P. Guerbois, and J. Harrison
Summary Due to growing environmental concerns and the need to use less energy-intensive building products, alternatives and improvements to Portland cement (PC) are being actively researched worldwide. Use of supplementary materials is now a common practice where PC is the predominant component of inorganic building products. This study aims to investigate the potential of magnesia (MgO), derived from a naturally occurring raw material magnesite, as a supplementary material. Results from mortar samples prepared with 10 and 20% replacements of ordinary Portland cement (OPC) by MgO are presented. DTA-TG was used to study and characterise the hydration behaviour of MgO in OPC environment after 3, 7, 14, 28, 56 and 90 days of moist curing. Microstructural and compressive strength determinations providing additional information on the influence of hydrated phases are also reported.
Authors:M. Oddone, Z. Yegingil, G. Bigazzi, T. Ercan, and M. Özdogan
Obsidian is a volcanic glass which is generally black, sometimes grey, brown, red or green in colour and characterised by a glassy appearance and conchoidal fractures. It is formed by the sudden cooling of the molten, generally acid magma with high water content. Obsidian was widely used for tool-making during prehistoric times. This work concems the chemical characterisation of obsidian occurrences from Northem, Central and Eastem Anatolia by Instrumental and Epithemal Neutron Activation Analysis for obtaining an accurate fingerprint for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts.
During the past several years, a significant effort has been on investigation of reaction front propagation and the rate of
energy release in heterogeneous systems consisting of nanopowder reactants. Substantial size reduction of each reactant powder
(e.g. from micro- to nano-size) leads to increase of reaction front propagation in some systems under unconfined conditions
by approximately two to three order of magnitude. This paper presents key challenges associated with processing and use of
nanothermite materials and characterization of nanoreactants. Reaction constants, such as activation energies and frequency
factors were determined using DSC technique for several nanothermite systems based on nanosize aluminum and iron oxide, bismuth
trioxide, and molybdenum trioxide. Experimental data of ignition delay times for different nanothermite systems using laser
energy source were compared well to those predicted by proposed mathematical model.