Assembling the puzzle of superconducting elements: A Review

Superconductivity in the simple elements is of both technological relevance and fundamental scientific interest in the investigation of superconductivity phenomena. Recent advances in the instrumentation of physics under pressure have enabled the observation of superconductivity in many elements not previously known to superconduct, and at steadily increasing temperatures. This article offers a review of the state of the art in the superconductivity of elements, highlighting underlying correlations and general trends.Comment: Review, 10 pages, 11 figures, 97 references; to appear in Superc. Sci. Techno

Similarity in the restrictiveness of bond covenants

We examine the economic determinants and consequences associated with the inclusion of covenants with similar levels of restrictiveness in bond contracts. Using a unique Moody’s bond covenant dataset, we develop measures that capture similarity in the restrictiveness of bond covenants relative to previously issued peer bonds. We document that the demand for similarity by issuers, their advisors and bond investors follows the predictions of sociological and economic theories. Further, consistent with similarity in covenants reducing bond investors’ information acquisition and processing costs, we show that bonds with more similar covenant restrictiveness receive lower yields at issuance. These bonds are also more likely to be held by long-term bond investors, such as insurance companies, and are characterized by greater liquidity in the secondary market, providing a partial explanation for the lower bond yields. Our results highlight the benefits of covenant similarity and suggest that the use of covenants with similar restrictiveness levels brings information acquisition and processing cost savings that may be larger than the monitoring benefits provided by covenants with more tailored features

Development and Characterisation of Gastroretentive Solid Dosage Form Based on Melt Foaming

Dosage forms with increased gastric residence time are promising tools to increase bioavailability of drugs with narrow absorption window. Low-density floating formulations could avoid gastric emptying; therefore, sustained drug release can be achieved. Our aim was to develop a new technology to produce low-density floating formulations by melt foaming. Excipients were selected carefully, with the criteria of low gastric irritation, melting range below 70°C and well-known use in oral drug formulations. PEG 4000, Labrasol and stearic acid type 50 were used to create metronidazole dispersion which was foamed by air on atmospheric pressure using in-house developed apparatus at 53°C. Stearic acid was necessary to improve the foamability of the molten dispersion. Additionally, it reduced matrix erosion, thus prolonging drug dissolution and preserving hardness of the moulded foam. Labrasol as a liquid solubiliser can be used to increase drug release rate and drug solubility. Based on the SEM images, metronidazole in the molten foam remained in crystalline form. MicroCT scans with the electron microscopic images revealed that the foam has a closed-cell structure, where spherical voids have smooth inner wall, they are randomly dispersed, while adjacent voids often interconnected with each other. Drug release from all compositions followed Korsmeyer-Peppas kinetic model. Erosion of the matrix was the main mechanism of the release of metronidazole. Texture analysis confirmed that stearic acid plays a key role in preserving the integrity of the matrix during dissolution in acidic buffer. The technology creates low density and solid matrix system with micronsized air-filled voids

Integrating uncertainties and stochastic effects into transportation network models at trip generation

W modelach sieci transportowych wiele zmiennych opisuje cechy fizyczne sieci. Integracja wynikowej niepewności jest tylko częściowa. Wiele tych zmiennych jest opartych na hipotezach i oszacowaniach. Metoda Monte Carlo jest efektywną narzędziem oceny scenariuszy, w których pewne zmienne nie mogą być opisane dokładnie. W artykule rozważano zastosowanie metody MC z zaproponowaną strukturą zmiennych losowych opisujących niepewność podczas generowania podróży. Powtarzanie obliczeń powoduje rosnącą dokładność wartości potoku ruchu na łuku i różnorodność funkcji rozkładu. Szczegóły analizy ilustrują trudności, które mogą pojawiać się podczas stosowania metody MC.Transportation network models contain numerous variables describing features of the physical network. Many of these variables are based on hypotheses or estimations. Integration of the implicated uncertainty is only partial. The Monte Carlo method is an effective tool for evaluating scenarios where certain variables could not be described precisely. This paper explores the application of the MC method with proposed random variable structure covering uncertainties of trip generation. Evaluation of repeated assignments show increasing detail of traffic flow values per link and a variety of distribution functions. Details of the analysis illustrate the difficulties which might arise when adopting the MC method