25,959 research outputs found

    Characterization of quasi-projectiles produced in symmetric collisions studied with INDRA Comparison with models

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    The characterization of hot quasi-projectiles produced in symmetric or quasi-symmetric reactions (Au + Au, Xe + Sn, Ni + Ni, Ar + KCl) at di erent incident energies are estimated by means of two di erent procedures. The advantages and disadvantages of each method are analyzed on the basis of simulations using events produced by two slightly di erent models: HIPSE and ELIE.Comment: A para\^itr

    Demonstration experiments for solid state physics using a table top mechanical Stirling refrigerator

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    Liquid free cryogenic devices are acquiring importance in basic science and engineering. But they can also lead to improvements in teaching low temperature an solid state physics to graduate students and specialists. Most of the devices are relatively expensive, but small sized equipment is slowly becoming available. Here, we have designed several simple experiments which can be performed using a small Stirling refrigerator. We discuss the measurement of the critical current and temperature of a bulk YBa2Cu3O(7-d) (YBCO) sample, the observation of the levitation of a magnet over a YBCO disk when cooled below the critical temperature and the observation of a phase transition using ac calorimetry. The equipment can be easily handled by students, and also used to teach the principles of liquid free cooling

    Photooxidation of Polymeric-inorganic nanocomposites: Chemical, Thermal Stability and Fire Retardancy Investigations

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    Nanocomposites of polypropylene-graft-maleic anhydride/clay and polypropylene/clay were prepared by melt blending using two different approaches. X-Ray diffraction results showed an intercalated structure. Samples of nanocomposites were exposed to UV light under atmospheric oxygen and their photo-oxidative stability was studied using FTIR and UV spectroscopy. The consequences of this photo-oxidation on the thermal stability and fire retardant performance of the nanocomposites were also addressed from thermogravimetry analysis and Cone calorimetry

    The ATLAS Detector: Status and Results from Cosmic Rays

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    The ATLAS detector at the Large Hadron Collider, CERN has been under construction for more than a decade. It is now largely complete and functional. This paper will describe the state of the major subsystems of ATLAS. Results from the brief single beam running period in 2008 will be shown. In addition, results from a long period of cosmic ray running will be shown. These results show that ATLAS is prepared to make major new physics discoveries as soon as we get colliding beams in late 2009.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

    Drug-Excipient Compatibility Studies in Formulation Development: Current Trends and Techniques

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    The safety, efficacy, quality and stability of a formulation are the cornerstones of any new drug development process. In order to consistently maintain these attributes in a finished dosage form, it is important to have a comprehensive understanding of the physico-chemical characteristics of the active pharmaceutical ingredient (API), as well as all other components (e.g. excipients, manufacturing aids, packaging materials) of the drug product. In a new drug development process, a detailed characterization of the API and other formulation components is usually carried out during the preformulation stage. The preformulation stage involves characterization of several aspects of the API including solubility, dissolution, permeability, polymorph/salt screening, stability (solidstate and solution-state), ionization properties, particle size distribution, API-excipient compatibilities etc. [1]. Excipients are ubiquitous to virtually every pharmaceutical formulation, and facilitate the manufacture, stability, administration, delivery of the API, and/or provide other functionalities to the dosage form. Excipients are used to improve processing (e.g. improving powder flow [2, 3], powder compactibility [4-6] etc.), enhance aesthetics (e.g. identification, branding etc. [7]), optimize product performance (e.g. modified drug-release [8-11]), and/or to facilitate patient compliance (e.g. taste masking [12-15]). They may constitute anywhere from 1 to 99 % of the total formulation mass. Due to the intimate contact of the API with one or more excipients in a formulation, there exists a likelihood of physical and/or chemical interactions between them. Any such interactions may result in a negative impact on the physical, stability or performance attributes of the drug product [16, 17]. The choice of excipients is of crucial importance to avoid these negative effects, and to facilitate the development of a robust and an effective formulation [18-20]. Thus, for a rational selection of excipients, screening of excipient-API compatibility is recognized as an important aspect of formulation development. Moreover, the USFDA’s 21st century current Good Manufacturing Practices (cGMP) initiative and International Council on Harmonization (ICH) Q8 guidelines encourage the pharmaceutical manufacturers to apply Quality by Design (QbD) principles in their drug development process [21, 22]. These guidelines include expectations of a clear understanding of any interactions between the formulation components. Moreover, recent advances in various thermal and non-thermal analytical techniques have led to an improved efficiency in the detection, monitoring and prevention of the incompatibilities early in the drug development process [23, 24]. This article aims to provide a brief overview of the nature of drug-excipient incompatibilities; as well as current trends and techniques used to evaluate these compatibilities in formulation development

    Precision Crystal Calorimetry in High Energy Physics

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    Crystal Calorimetry is widely used in high energy physics because of its precision. Recent development in crystal technology identified two key issues to reach and maintain crystal precision: light response uniformity and calibration in situ. Crystal radiation damage is understood. While the damage in alkali halides is found to be caused by the oxygen/hydroxyl contamination, it is the structure defects, such as oxygen vacancies, cause damage in oxides.Comment: 8 pages with 13 eps Figures, RevTe
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