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Area Calculation (area + calculation)
Selected AbstractsSample preparation effects in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry of partially depolymerised methyl celluloseRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2003Dane Momcilovic Methyl cellulose (MC) was partially depolymerised and the oligomers thus obtained were studied by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The depolymerisation was either enzymatic or acidic. Fractions of enzymatically depolymerised MC were collected from size-exclusion chromatography and subjected to a sample preparation investigation. Several MALDI matrices and solvents were evaluated. The results showed that the solvent choice had a significant effect on the measured degree of substitution (DS). Aprotic solvents produced higher DS values, which was most likely due to poor solubility of species with low DS. The obtained signal intensity, however, did not correlate with the solubility but seemed to be more dependent on certain matrix/solvent combinations. All the matrices attempted produced mass spectra with sufficient signal intensity for accurate peak area calculation. The choice of matrix did not have any significant effect on the measured DS. Sample spots obtained from organic solvents had a more homogeneous distribution of the analyte and smaller crystals than those obtained from water. This increased both the reproducibility and peak resolution and in addition the analysis time was shorter. DS measurements were performed on two acidically depolymerised MCs with different nominal DS values. It was easy to distinguish between the two MCs, and the measured DS values agreed well with the values supplied by the manufacturers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Vereinfachtes Flächenerfassungsmodell für MehrzonenbilanzenBAUPHYSIK, Issue 3 2009Markus Lichtmeß Dipl.-Ing. Berechnungsverfahren; Technische Regelwerke Abstract Bei der energetischen Bilanzierung nach DIN V 18599 müssen Gebäude aufgrund unterschiedlicher Nutzungseigenschaften zoniert werden. Auch die Gebäudehüllfläche wird nach diesen Kriterien aufgeteilt und den Zonen zur weiteren Berechnung zugewiesen. In der Praxis ist die Aufteilung der inneren Zonenumschließungs- und der äußeren Gebäudehüllfläche mit einem hohen Arbeitsaufwand verbunden. Etwa 50 % der Zeit wird für die Zonierung und die Ermittlung dieser Flächen- und Bauteileigenschaften benötigt. Zur Verringerung des Zeitaufwandes wurde eine Methode entwickelt, mit welcher die Gebäudehülle ähnlich dem 1-Zonen-Modell erfasst werden kann. Die Hüllfläche wird den Zonen vereinfacht zugeordnet, sodass die eigentliche Berechnung in der Mehrzonenbilanz erfolgen kann. Dies bringt wesentliche Vorteile bei der Auslegung und Optimierung nachgeschalteter Anlagentechnik mit sich. Die Verteilung der thermischen Hüllflächen erfolgt bei diesem vereinfachten Verfahren in Abhängigkeit von der Zonengröße und kann über ein Wichtungsverfahren beeinflusst bzw. korrigiert werden. Untersuchungen an mehreren Gebäuden haben gezeigt, dass die Flächenverteilung mit einer guten Genauigkeit eingesetzt werden kann, wobei eine "intelligente" Zuteilung über ein Wichtungsverfahren erforderlich ist. Die Zeitersparnis bei Anwendung der Vereinfachungen beträgt etwa 30 %. Bei komplexeren, vielzonigen Gebäuden ist die Einsparung tendenziell höher einzuschätzen. Das Verfahren erlaubt, alle Bauteilflächen detailliert auf Zonenebene nachzueditieren und somit die Möglichkeit, das Gebäudemodell planungsbegleitend zu konkretisieren. So kann die Berechnung im Laufe der Projektbearbeitung immer weiter präzisiert werden, wodurch die Berechnungsgenauigkeit und die Optimierungsmöglichkeiten gesteigert werden. Diese Vereinfachungen sollen zukünftig in der Luxemburger EnEV zur energetischen Bewertung von neu zu errichtenden Nichtwohngebäuden nach DIN V 18599 Anwendung finden. A simplified surface area calculation and zoning model for energy performance assessment of buildings. According to the DIN V 18599 energy performance assessment, buildings have to be divided into zones depending on their utilisation. The same zoning applies to the building envelope where the segments are being allocated to the individual zones. In engineering practice about 50% of the work is required for zoning, calculating surface areas and evaluating the properties of building envelope components. In order to reduce the time needed for these efforts a methodology similar to the single zone model has been developed. To carry out the multiple zone calculation the building envelope is being split and allocated to the individual zones in a simplified way. This as well provides a significant advantage for the dimensioning and optimisation of the related HVAC and lighting systems. Within the simplified calculation, the allocation of the building envelope is carried out in dependence of the zone size and corrected with a weighting factor if needed. The analysis of several buildings has shown that the simplified method can be applied with sufficient accuracy. The weighting factors are however necessary. By implementing this simplification the time expenditure to calculate a building is reduced by more or less 30%. This reduction tends to be even more important when dealing with complex buildings which have a high number of zones. The methodology enables building components to be edited by zones and hereby gives the opportunity to easily modify the design during the course of the planning. As the project develops, the calculations can be more detailed thereby increasing the precision of the calculation. In the near future this methodology will be implemented in the Luxembourg energy saving ordinance (EnEV) for the energy performance assessment of non residential buildings. [source] Global patterns of plant diversity and floristic knowledgeJOURNAL OF BIOGEOGRAPHY, Issue 7 2005Gerold Kier Abstract Aims, We present the first global map of vascular plant species richness by ecoregion and compare these results with the published literature on global priorities for plant conservation. In so doing, we assess the state of floristic knowledge across ecoregions as described in floras, checklists, and other published documents and pinpoint geographical gaps in our understanding of the global vascular plant flora. Finally, we explore the relationships between plant species richness by ecoregion and our knowledge of the flora, and between plant richness and the human footprint , a spatially explicit measure of the loss and degradation of natural habitats and ecosystems as a result of human activities. Location, Global. Methods, Richness estimates for the 867 terrestrial ecoregions of the world were derived from published richness data of c. 1800 geographical units. We applied one of four methods to assess richness, depending on data quality. These included collation and interpretation of published data, use of species,area curves to extrapolate richness, use of taxon-based data, and estimates derived from other ecoregions within the same biome. Results, The highest estimate of plant species richness is in the Borneo lowlands ecoregion (10,000 species) followed by nine ecoregions located in Central and South America with , 8000 species; all are found within the Tropical and Subtropical Moist Broadleaf Forests biome. Among the 51 ecoregions with , 5000 species, only five are located in temperate regions. For 43% of the 867 ecoregions, data quality was considered good or moderate. Among biomes, adequate data are especially lacking for flooded grasslands and flooded savannas. We found a significant correlation between species richness and data quality for only a few biomes, and, in all of these cases, our results indicated that species-rich ecoregions are better studied than those poor in vascular plants. Similarly, only in a few biomes did we find significant correlations between species richness and the human footprint, all of which were positive. Main conclusions, The work presented here sets the stage for comparisons of degree of concordance of plant species richness with plant endemism and vertebrate species richness: important analyses for a comprehensive global biodiversity strategy. We suggest: (1) that current global plant conservation strategies be reviewed to check if they cover the most outstanding examples of regions from each of the world's major biomes, even if these examples are species-poor compared with other biomes; (2) that flooded grasslands and flooded savannas should become a global priority in collecting and compiling richness data for vascular plants; and (3) that future studies which rely upon species,area calculations do not use a uniform parameter value but instead use values derived separately for subregions. [source] Comparison of binding energies of SrcSH2-phosphotyrosyl peptides with structure-based prediction using surface area based empirical parameterizationPROTEIN SCIENCE, Issue 10 2000Denise A. Henriques Abstract The prediction of binding energies from the three-dimensional (3D) structure of a protein,ligand complex is an important goal of biophysics and structural biology. Here, we critically assess the use of empirical, solvent-accessible surface area-based calculations for the prediction of the binding of Src-SH2 domain with a series of tyrosyl phosphopeptides based on the high-affinity ligand from the hamster middle T antigen (hmT), where the residue in the pY+3 position has been changed. Two other peptides based on the C-terminal regulatory site of the Src protein and the platelet-derived growth factor receptor (PDGFR) are also investigated. Here, we take into account the effects of proton linkage on binding, and test five different surface area-based models that include different treatments for the contributions to conformational change and protein solvation. These differences relate to the treatment of conformational flexibility in the peptide ligand and the inclusion of proximal ordered solvent molecules in the surface area calculations. This allowed the calculation of a range of thermodynamic state functions (,Cp, ,S, ,H, and ,G) directly from structure. Comparison with the experimentally derived data shows little agreement for the interaction of SrcSH2 domain and the range of tyrosyl phosphopeptides. Furthermore, the adoption of the different models to treat conformational change and solvation has a dramatic effect on the calculated thermodynamic functions, making the predicted binding energies highly model dependent. While empirical, solvent-accessible surface area based calculations are becoming widely adopted to interpret thermodynamic data, this study highlights potential problems with application and interpretation of this type of approach. There is undoubtedly some agreement between predicted and experimentally determined thermodynamic parameters; however, the tolerance of this approach is not sufficient to make it ubiquitously applicable. [source] | ||||||||||