RESUMEN
The formation of layer-like FAU-type zeolites was facilitated in the absence of any organic template. Instead, the addition of simple inorganic salts turned out to be an effective and easy to handle alternative to organic additives to induce morphological and even structural changes during zeolite crystallisation.
Asunto(s)
Litio/química , Zeolitas/síntesis química , Zinc/química , Cationes/química , Técnicas de Química Sintética , Cristalización , Zeolitas/químicaRESUMEN
Predicting physical properties of materials with spatially complex structures is one of the most challenging problems in material science. One key to a better understanding of such materials is the geometric characterization of their spatial structure. Minkowski tensors are tensorial shape indices that allow quantitative characterization of the anisotropy of complex materials and are particularly well suited for developing structure-property relationships for tensor-valued or orientation-dependent physical properties. They are fundamental shape indices, in some sense being the simplest generalization of the concepts of volume, surface and integral curvatures to tensor-valued quantities. Minkowski tensors are based on a solid mathematical foundation provided by integral and stochastic geometry, and are endowed with strong robustness and completeness theorems. The versatile definition of Minkowski tensors applies widely to different types of morphologies, including ordered and disordered structures. Fast linear-time algorithms are available for their computation. This article provides a practical overview of the different uses of Minkowski tensors to extract quantitative physically-relevant spatial structure information from experimental and simulated data, both in 2D and 3D. Applications are presented that quantify (a) alignment of co-polymer films by an electric field imaged by surface force microscopy; (b) local cell anisotropy of spherical bead pack models for granular matter and of closed-cell liquid foam models; (c) surface orientation in open-cell solid foams studied by X-ray tomography; and (d) defect densities and locations in molecular dynamics simulations of crystalline copper.
Asunto(s)
Algoritmos , Metales/química , Simulación de Dinámica Molecular , Polímeros/química , PorosidadRESUMEN
The present work demonstrates enhanced photocatalytic activity for zeolite-filled TiO2 nanotubes. ZSM-5 zeolite nanocrystals were grown on and into a TiO2 nanotubular skeleton (TiNT/ZSM-5) by multi-step hydrothermal synthesis consisting of in situ seeding and multiple in situ crystallization (MISC). The resulting zeolite nanocrystals were in the range of a few nanometers and they adhere well to the nanotubular inner walls. After crystallization, the photocatalytic activity of this zeolite-filled nanotube catalyst system was compared with neat anatase TiO2 nanotube (TiNT) and with calcined ZSM-5 powder. The results show for TiNT/ZSM-5 a highly enhanced efficiency for the decomposition of acetophenone (used as an aromatic model organic pollutant).
RESUMEN
BACKGROUND: Abbottonians Medical Association, Abbottabad, Pakistan in collaboration with UNAIDS Pakistan arranged two Workshops, the first in 1999, the Theme of which was "Listen, Learn, Live", and the second in the year 2000 with "Men Make Difference" as the Theme. The aim of these workshops was to create awareness amongst the participants regarding HIV/AIDS. OBJECTIVES: We used the data of the above-mentioned workshops to analyze the gain in knowledge and attitudes of the participants, with an idea to develop recommendations for the use of such workshops for increasing the awareness regarding HIV/AIDS. METHODS: The data of the two above-mentioned workshops were used to assess the percentage gain in knowledge and attitudes of the participants. We also compared our results with the contemporary studies and developed our recommendations. RESULTS: The results show highly significant (p < .001) increase in the HIV/AIDS related knowledge and attitudes in the participants of these workshops. This difference was more significant in the teachers as compared to the students, showing a higher level of awareness in the youngsters. The net gain in the knowledge was very significant. The knowledge about HIV spread increased by 28.96% for the students and 19.54% for the teachers, while the net gain in attitudes was 36.16% for the students and 71.43% in the teachers. CONCLUSIONS: Short workshops on the Themes of World AIDS Days are very beneficial for improvement in the level of awareness for HIV/AIDS prevention and control.