High-Tc superconductor YBa2Cu307-.5 studied by positron annihilation

We have measured the positron-lifetime and the Doppler-broadening spectra in the hightemperature superconductor YBa2Cu30 7 - 6 as a function of temperature between 77 and 295 K. Positron-lifetime and Doppler-broadening data show new features in the superconducting phase. These results are interpreted in terms of positron localization in lattice distortions and posi~ron surface states

Understanding Islam: Development, Economics and Finance

In this paper, the foundational rules governing human, economic and financial development in Islam, as understood from the Quran and from the life and traditions of the Prophet Muhammad (pbuh), are summarized. These rules pave the path to development as the basis of institutional structure, which in turn, underpin the path of economic and social progress. The essential elements in the life of a Muslim—the unity of creation, freedom and freedom of choice, economic and human development, economic system and financial practice—are developed

DOPAGE ET DEGRADATION DU POLYACETYLENE PAR L'ACIDE NITRIQUE

L'action de HNO3 vapeur sur le trans-polyacétylène conduit d'une part à la formation d'un complexe de transfert de charge et d'autre part à une dégradation causée par la rupture des doubles liaisons carbone-carbone. Ces réactions ont été mises en évidence à l'aide de différentes techniques : mesure de la résistivité électrique, spectroscopies infra-rouge et Raman, RPE.The reaction of HNO3 on trans (CH)x leads to two different reactions (doping and degradation) which have been followed by various physical measurements : variation in time of the electrical resistivity, IR and Raman spectroscopies and EPR