The materials community in both science and industry use crystallographic data models on a daily basis to visualize, explain and predict the behavior of chemicals and materials. Access to reliable information on the structure of crystalline materials helps researchers concentrate experimental work in directions that optimize the discovery process. The Inorganic Crystal Structure Database (ICSD) is a comprehensive collection of more than 60 000 crystal structure entries for inorganic materials and is produced cooperatively by Fachinformationszentrum Karlsruhe (FIZ), Germany, and the US National Institute of Standards and Technology (NIST). The ICSD is disseminated in computerized formats with scienti®c software tools to exploit the content of the database. Features of a new Windows-based graphical user interface for the ICSD are outlined, together with directions for future development in support of materials research and design.
Scintillating nanoparticles (NPs) in combination with X-ray or γ-radiation have a great potential for deep-tissue cancer therapy because they can be used to locally activate photosensitizers and generate singlet oxygen in tumours by means of the photodynamic effect. To understand the complex spatial distribution of energy deposition in a macroscopic volume of water loaded with nanoscintillators, we have developed a GEANT4-based Monte Carlo program. We thus obtain estimates of the maximum expected efficiency of singlet oxygen production for various materials coupled to PS, X-ray energies, NP concentrations and NP sizes. A new parameter, ηnano, is introduced to quantify the fraction of energy that is deposited in the NPs themselves, which is crucial for the efficiency of singlet oxygen production but has not been taken into account adequately so far. We furthermore emphasise the substantial contribution of primary interactions taking place in water, particularly under irradiation with high energy photons. The interplay of all these contributions to the photodynamic effect has to be taken into account in order to optimize nanoscintillators for therapeutic applications.
The role of charge carrier trapping
in determining radioluminescence
(RL) efficiency increase during prolonged irradiation of scintillators
has been studied by using YPO4:Ce,Nd as a model material.
The Nd3+ ions act as efficient electron traps minimizing
the role of intrinsic defects. Different Nd contents were considered
in order to point out the correlation between the trap concentration
and the detected RL efficiency dose dependence. RL measurements as
a function of temperature clarified the role of the trap thermal stability
in determining the shape and the magnitude of such effect. We propose
also a model based on trap filling which is able to describe accurately
the complex processes which are involved.
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