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Component System (component + system)
Selected AbstractsFormation of Nanostructures in Multi Component Systems Based on Organic Polymer and Coordination Metal CompoundMACROMOLECULAR SYMPOSIA, Issue 1 2006Nataly Kozak Abstract Structuring of polyurethane (PU) networks is analyzed under influence of transition metal coordination compounds: mono-ionic ,-diketonates and polyheteronuclear metal-organic complexes. Formed in situ nanostructures both organic and inorganic were found in organic polymer modified with coordination metal compound. Influence of coordination junction point spatial symmetry and content of metal ion in modifier on structure and dielectric characteristics of modified PUs is analyzed using X-ray, EPR, SEM and transmission optical microscopy, DRS and DSC methods. [source] Students' experience of component versus integrated virtual learning environmentsJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 4 2005M. Weller Abstract The use of virtual learning environments (VLEs) has become increasingly common in most higher education (HE) institutions. Recent developments have proposed the interoperability of software systems and content, to create component VLEs in contrast with the integrated, monolithic ones that are currently prevalent. This paper examines the student experience of two VLEs, one integrated approach and the other component. In general, students preferred the component system, although this may have been influenced by other factors such as performance. Although the study is limited to one cohort of student it makes a number of suggestions relevant to anyone deploying a VLE. These are that the component approach is a viable one from a student perspective, the broader context in which the VLE operates is important in student perception and that poor system performance may have unpredictable consequences for the learning experience. [source] Forensic Age-at-Death Estimation from the Human Sacrum,JOURNAL OF FORENSIC SCIENCES, Issue 2 2009Nicholas V. Passalacqua M.S. Abstract:, A new method is described here that incorporates seven developmental and degenerative changes for estimating chronological age from morphological features of the human sacrum. The construction of this method involved multiple stages of trait identification, character-state definition and age correlation, rank-order phase development, and percent-correct sample testing with phase and sample aggregation, all of which resulted in a six-phase component system for application on modern individuals. This phase system was first developed on European American male and female samples from the Hamann-Todd collection; then tested on African American male and female Hamann-Todd samples as well as European American male and females from the WM Bass collection to examine possible sex and/or ancestry differences. Variation in age estimates due to sex and ancestry was negligible; thus, the multiple samples were all pooled creating a robust method with a large sample size. Overall age ranges increase in width at two standard deviations as is expected from degenerative age-related processes but retain utility in forensic situations. [source] LIGHT REGULATION OF PHYCOBILISOME BIOSYNTHESIS AND CONTROL BY A PHYTOCHROME-LIKE PHOTORECEPTORJOURNAL OF PHYCOLOGY, Issue 2000K. Terauchi Ambient light quality changes dramatically affect the composition of light harvesting structures, the phycobilisomes, in many cyanobacterial species. In the cyanobacterium Fremyella diplosiphon, shifts in the ratio of red to green light lead to transcriptional changes and altered synthesis of several phycobilisome components. This process is called complementary chromatic adaptation (CCA). These two colors have opposite effects: red light activates an operon encoding the biliprotein phycocyanin (PC) and inactivates the operon encoding phycoerythrin (PE), whereas green light activates PE synthesis and shuts down PC synthesis. The effects of red and green light on CCA are photoreversible. Thus, CCA is similar to transcriptional processes that are controlled by phytochromes, a family of eukaryotic red/far red photoreversible photoreceptors. We are using molecular genetics to determine the mechanisms by which F. diplosiphon senses changes in the color of light of its environment. Initial mutant generation and complementation lead to the discovery of three CCA regulatory components that are part of a complex two component system. The most interesting of these is RcaE (regulator of chromatic adaptation), a histidine kinase-class protein containing a region in its amino-terminal half with similarity to the chromophore binding domains of phytochromes. Within this region, RcaE contains a cysteine residue in a similar location as that used for covalent attachment of the open-chain tetrapyrrole chromophore in phytochromes. We will present recent data characterizing RcaE, including in vivo analysis of the chromophore that is attached to RcaE, as well as results from our recent isolation of a new CCA regulatory component. [source] Effect of molecular weight, temperature, and additives on the moisture sorption properties of polyethylene glycolJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2010Jared A. Baird Abstract Polyethylene glycol (PEG) is a hygroscopic polymer that undergoes the phenomenon of deliquescence once a critical relative humidity (RH0) is reached. The purpose of this study was to test the hypothesis that the deliquescence behavior of PEG will be affected by the polymer molecular weight, temperature, and the presence of additives. The deliquescence relative humidity for single component (RH0) and binary mixtures (RH0,mix) were measured using an automated gravimetric moisture analyzer at 25 and 40°C. Changes in PEG crystallinity after exposure to moisture were qualitatively assessed using powder X-ray diffraction (PXRD). Optical microscopy was used to visually observe the deliquescence phenomenon. For single component systems, decreasing PEG MW and elevating the temperature resulted in a decrease in the observed RH0. Physical mixtures of acetaminophen and anhydrous citric acid with both PEG 3350 and PEG 100,000 exhibited deliquescence (RH0,mix) at a relative humidity below that of either individual component. Qualitative changes in crystallinity were observed from the X-ray diffractograms for each PEG MW grade at high relative humidities, indicating that phase transformation (deliquescence) of the samples had occurred. In conclusion, it was found that the deliquescence behavior of PEG was affected by the polymer MW, temperature, and the presence of additives. This phenomenon may have important implications for the stability of PEG containing formulations. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:154,168, 2010 [source] Analysis of the influence of coupled diffusion on transport in protein crystal growth for different gravity levelsACTA CRYSTALLOGRAPHICA SECTION D, Issue 10-1 2002D. Castagnolo Diffusion has a central role in protein crystal growth both in microgravity conditions and on ground. Recently several reports have been focused on the importance to use the generalized Fick's equations in n -component systems where crystals grow. In these equations the total flux of each component is produced by the own concentration gradient (main flow) and by the concentration gradient of the other components (cross-flow) present in the system. However in literature the latter effect is often neglected, and the so-called pseudo-binary approximation is used. Lin et al. (1995) proposed a mathematical model to evaluate the concentration profile of the species present around a growing protein crystal. Although the model is reliable, it suffers of the pseudo-binary approximation (neglecting cross term diffusion coefficients and using binary diffusion coefficients), probably because of the lack of multicomponent diffusion data. The present model is based on the experimental set-up proposed by Lin et al. (1995). Nevertheless we have included the coupled diffusion effects, according to the correct description of the matter transport through the generalized Fick's equations. The crystal growth rate is calculated for different gravity levels. The model has been applied to the ternary lysozyme-NaCl-water and quaternary lysozyme-poly(ethylene glycol) (PEG)-NaCl-water systems using recent diffusion data. [source] Assessment and Statistics of Surgically Induced AstigmatismACTA OPHTHALMOLOGICA, Issue thesis1 2008Kristian Nęser Abstract. The aim of the thesis was to develop methods for assessment of surgically induced astigmatism (SIA) in individual eyes, and in groups of eyes. The thesis is based on 12 peer-reviewed publications, published over a period of 16 years. In these publications older and contemporary literature was reviewed1. A new method (the polar system) for analysis of SIA was developed. Multivariate statistical analysis of refractive data was described2,4. Clinical validation studies were performed. The description of a cylinder surface with polar values and differential geometry was compared. The main results were: refractive data in the form of sphere, cylinder and axis may define an individual patient or data set, but are unsuited for mathematical and statistical analyses1. The polar value system converts net astigmatisms to orthonormal components in dioptric space. A polar value is the difference in meridional power between two orthogonal meridians5,6. Any pair of polar values, separated by an arch of 45 degrees, characterizes a net astigmatism completely7. The two polar values represent the net curvital and net torsional power over the chosen meridian8. The spherical component is described by the spherical equivalent power. Several clinical studies demonstrated the efficiency of multivariate statistical analysis of refractive data4,9,11. Polar values and formal differential geometry describe astigmatic surfaces with similar concepts and mathematical functions8. Other contemporary methods, such as Long's power matrix, Holladay's and Alpins' methods, Zernike12 and Fourier analyses8, are correlated to the polar value system. In conclusion, analysis of SIA should be performed with polar values or other contemporary component systems. [source] | ||||||||||