Die Bestimmung von o-Nitrotoluol in Nitrocellulosepulver mittels des Eintauchrefraktometers

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Middle School Students' Conceptual Learning from the Implementation of a New NSF Supported Curriculum: Interactions in Physical Science™

A new National Science Foundation supported curriculum, Interactions in Physical Science?, was evaluated on students’ conceptual change in the twelve concept areas of the national physical science content standard (B) for grades 5–8. Eighth grade students (N=66) were evaluated pre and post on a 31‐item multiple‐choice test of conceptual understanding developed by the Harvard ‐Smithsonian Center for Astrophysics. Significant student gains (p<. 05, t‐test, two‐tailed) occurred in all concept areas in the category of properties and changes in properties of matter; for the force concept areas in the category motions and forces; and for the heat transfer and light interactions areas in the category of transfer of energy. Two of the six concept areas in the category of transfer of energy, chemical and nuclear reactions and the sun as a major source of energy, were not addressed in this study. Significant learning gains as item percent correct were typically close to 20%, though effect sizes were small to medium in magnitude (d = 0.3–0.6). Implications of the study for conceptual change curriculum and teaching are discussed.     

Minerals,sediments and coals

A survey is presented of some of the recent uses of Mössbauer spectroscopy in studying chemical changes in mineral systems. The changes considered include those occurring naturally, such as weathering, leaching, soil formation, lake and river sedimentation and coal oxidation, and some induced by man, such as chemical leaching, precipitate ageing, coal hydroliquefaction and ash resulting from coal combustion.     

On box totally dual integral polyhedra

Edmonds and Giles introduced the class of box totally dual integral polyhedra as a generalization of submodular flow polyhedra. In this paper a geometric characterization of these polyhedra is given. This geometric result is used to show that each TDI defining system for a box TDI polyhedron is in fact a box TDI system, that the class of box TDI polyhedra is in co-NP and is closed under taking projections and dominants, that the class of box perfect graphs is in co-NP, and a result of Edmonds and Giles which is related to the facets of box TDI polyhdera.Supported by a grant from the Alexander von Humboldt-Stiftung.     

Extending the GGobi pipeline from R

This paper describes progress towards developing a platform for rapid prototyping of interactive data visualizations, using R, GGobi, rggobi and RGtk2. GGobi is a software tool for multivariate interactive graphics. At the core of GGobi is a data pipeline that incrementally transforms data through a series of stages into a plot and maps user interaction with the plot back to the data. The GGobi pipeline is extensible and mutable at runtime. The rggobi package, an interface from the R language to GGobi, has been augmented with a low-level interface that supports the customization of interactive data visualizations through the extension and manipulation of the GGobi pipeline. The large size of the GGobi API has motivated the use of the RGtk2 code generation system to create the low-level interface between R and GGobi. The software is demonstrated through an application to interactive network visualization.     

High‐temperature shock tube study of the reactions CH3 + OH → products and CH3OH + Ar → products

The reaction between methyl and hydroxyl radicals has been studied in reflected shock wave experiments using narrow‐linewidth OH laser absorption. OH radicals were generated by the rapid thermal decomposition of tert‐butyl hydroperoxide. Two different species were used as CH₃ radical precursors, azomethane and methyl iodide. The overall rate coefficient of the CH₃ + OH reaction was determined in the temperature range 1081–1426 K under conditions of chemical isolation. The experimental data are in good agreement with a recent theoretical study of the reaction. The decomposition of methanol to methyl and OH radicals was also investigated behind reflected shock waves. The current measurements are in good agreement with a recent experimental study and a master equation simulation. © 2008 Wiley Periodicals, Inc. 40: 488–495, 2008     

Ein Verfahren zur Bestimmung der Harns?ure

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Synthesis,photopolymerization, and adhesive properties of new bisphosphonic acid monomers for dental application

Four new monomers, 3‐(N‐methylacrylamido)propylidenebisphosphonic acid, 3‐(N‐propyl‐acrylamido)propylidenebisphosphonic acid, 3‐(N‐hexylacrylamido)propylidenebisphosphonic acid, and 3‐(N‐octylacrylamido)propylidenebisphosphonic acid, have been synthesized in good yields and fully characterized by ¹H, ¹³C, ³¹P NMR, and HRMS. The copolymerization of these monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane (DEBAAP) has been investigated with differential scanning calorimetry. These mixtures show a higher reactivity than DEBAAP. New self‐etch dental primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on these bisphosphonic acids assure a strong bond between the tooth substance and a dental composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5258–5271, 2009