Nanostructured micronized solid dispersion of crystalline-amorphous metronidazole embedded in amorphous polymer matrix prepared by nano spray drying

In this study metronidazole drug was encapsulated by hydroxypropyl methylcellulose and polyvinylpyrrolidone polymers from solutions using nano spray drying technology. The influence of the process parameters and formulation variables were investigated on product morhology and structure, production yield and entrapment efficiency. The use of surface active admixtures (polyvinyl alcohol, Tween-80 and Pluronic F68) increased the product yield substantially. The entrapped metronidazole was partially in crystalline and amorphous state in both amorphous polymers as confirmed by DSC and powder X-ray diffraction measurements. In the composites with hydroxypropyl methylcellulose the degree of crystallinity was between 50.2 and 81.0%, and with polyvinylpyrrolidone between 35.0 and 50.0% (with respect to the drug content). Melting point decrease phenomena was observed by differential scanning calorimetry between bulk metronidazole and spray dried products. Peak broadening was indicated by powder X-ray diffraction measurements, which could be the result of formation of small drug crystallites. The TEM images showed beside the larger crystals (200–400 nm) a fraction of smaller crystals (20–50 nm in diameter), which are in good correlation with the calculated coherent scattering domain sizes of 19–87 nm based on X-ray data. The drug-polymer composites produced by nano spray drying process were identified as crystalline-amorphous nanostructured micronized solid dispersions.     

Improved upper bounds on synchronizing nondeterministic automata

We show that i-directable nondeterministic automata can be i-directed with a word of length O(2ⁿ) for i=1,2, where n stands for the number of states. Since for i=1,2 there exist i-directable automata having i-directing words of length Ω(2ⁿ), these upper bounds are asymptotically optimal. We also show that a 3-directable nondeterministic automaton with n states can be 3-directed with a word of length , improving the previously known upper bound O(2ⁿ). Here the best known lower bound is .     

Scalability analysis of Dalton,a molecular structure program

Dalton is a molecular electronic structure program featuring common methods of computational chemistry that are based on pure quantum mechanics (QM) as well as hybrid quantum mechanics/molecular mechanics (QM/MM). It is specialized and has a leading position in calculation of molecular properties with a large world-wide user community (over 2000 licenses issued). In this paper, we present a performance characterization and optimization of Dalton. We also propose a solution to avoid the master/worker design of Dalton to become a performance bottleneck for larger process numbers. With these improvements we obtain speedups of 4x, increasing the parallel efficiency of the code and being able to run in it in a much bigger number of cores.     

3D shape estimation in video sequences provides high precision evaluation of facial expressions

Person independent and pose invariant estimations of facial expressions and action unit (AU) intensity estimation are important for situation analysis and for automated video annotation. We evaluated raw 2D shape data of the CK+ database, used Procrustes transformation and the multi-class SVM leave-one-out method for classification. We found close to 100% performance demonstrating the relevance and the strength of details of the shape. Precise 3D shape information was computed by means of constrained local models (CLM) on video sequences. Such sequences offer the opportunity to compute a time-averaged ‘3D personal mean shape’ (PMS) from the estimated CLM shapes, which – upon subtraction – gives rise to person independent emotion estimation. On CK+ data PMS showed significant improvements over AU0 normalization; performance reached and sometimes surpassed state-of-the-art results on emotion classification and on AU intensity estimation. 3D PMS from 3D CLM offers pose invariant emotion estimation that we studied by rendering a 3D emotional database for different poses and different subjects from the BU 4DFE database. Frontal shapes derived from CLM fits of the 3D shape were evaluated. Results demonstrate that shape estimation alone can be used for robust, high quality pose invariant emotion classification and AU intensity estimation.     

Astrophysics publications on arXiv,Scopus and Mendeley: a case study

In this study we examined a sample of 100 European astrophysicists and their publications indexed by the citation database Scopus, submitted to the arXiv repository and bookmarked by readers in the reference manager Mendeley. Although it is believed that astrophysicists use arXiv widely and extensively, the results show that on average more items are indexed by Scopus than submitted to arXiv. A considerable proportion of the items indexed by Scopus appear also on Mendeley, but on average the number of readers who bookmarked the item on Mendeley is much lower than the number of citations reported in Scopus. The comparisons between the data sources were done based on the authors and the titles of the publications.     

Ellipsometric study of SixC films: Analysis of Tauc-Lorentz and Gaussian oscillator models

In this study, the suitability of Tauc-Lorentz and Gaussian oscillator models to describe amorphous silicon-carbon alloys of various compositions was tested. The dependence of the model parameters on the composition showed that the amplitude and broadening of both oscillators behave similarly and significant differences can only be observed in the oscillators’ position in case of high broadening parameter values. It was shown that this difference originates from the different mathematical forms of the oscillators and from the high broadening values. Sensitivity analysis of the parameters showed that the models became less sensitive to their parameters with large broadening values. Furthermore the model parameters were correlated to the various types of chemical bonding present within the samples.     

Characterization of pulsed laser deposited hydrogenated amorphous silicon films by spectroscopic ellipsometry

The wide absorption band of hydrogenated amorphous silicon (a-Si:H) is being realized as a key component of solar cells on glass. In this study, a-Si:H films were prepared by reactive pulsed laser deposition onto silicon and glass substrates. Ellipsometry showed that the optical properties of the films are effectively independent on the choice of substrate. According to the optical properties, the character of the films changes from amorphous silicon to dielectric as the hydrogen background pressure increases from 0 to 25 Pa. This observation was attributed to oxygen incorporation indicated by Rutherford Backscattering Spectrometry. Furthermore, a refractive index gradient in depth was revealed, which was attributed to the oxygen concentration gradient.     

Self-linking and self-linked rates of academic institutions on the Web

In this paper we introduce two measures self-linked and self-linkingthat are the analogues of self-citing and self-cited rates for scientific journals. These rates are calculated for a sample of sites to assess their meaning and utility. Self-linked is the more meaningful measure for the sample sites. As a first step towards a better understanding of self-linking (linking within a site), a sample of pages from an academic site was characterized using the method of content analysis. Even though most of the links serve navigational or other technical purposes, the percentage of content-bearing links among the self-links is significant, and even the portion of research oriented links is non-negligible.     

The sources used by bibliometrics-scientometrics as reflected in references

The aim of this study was to examine the extent to which the field of bibliometrics and scientometrics makes use of sources outside the field. The research was carried out by examining the references of articles published in Scientometrics in the course of two calendar years, 1990, 2000. The results show that in 2000, 56.9% (and 47.3% in 1990) of the references originated from three fields: scientometrics and bibliometrics; library and information science; and the sociology, history and philosophy of science. When comparing the two periods, there is also a considerable increase in journal self-citation (i.e., references to the journal Scientometrics) and in the percentage of references to journals. This revised version was published online in June 2006 with corrections to the Cover Date.     

Eugene Garfield on the Web in 2001

This paper reports on the results of an extensive search for information on Eugene Garfield on the World Wide Web. The searches took place in August 2001, using the search terms: “Eugene Garfield”, “Garfield Eugene”, “Gene Garfield”, “E. Garfield” and “Garfield E”. The five major search engines at that time were queried. 9711 different URLs were identified, out of which 4120 were related to Eugene Garfield, the information scientist. About 25% of these pages were characterized using the method of content analysis. The pages were classified into multiple facets: theme, substantiality, page type, publisher, creator, language, domain and site. The findings show that the most frequently mentioned themes (not surprisingly) were the use and theory of citation analysis, the Citation Indexes as products, the Impact Factor and the use of JCR data. Over 50% of the pages were scientific in nature and more than a third of the pages formally cited Garfield’s work. The findings based on the 2001 dataset were not published before.