Gravitational energy-momentum density in teleparallel gravity

In the context of a gauge theory for the translation group, a conserved energy-momentum gauge current for the gravitational field is obtained. It is a true spacetime and gauge tensor, and transforms covariantly under global Lorentz transformations. By rewriting the gauge gravitational field equation in a purely spacetime form, it becomes the teleparallel equivalent of Einstein's equation, and the gauge current reduces to the Moller's canonical energy-momentum density of the gravitational field.     

Synthesis of repeating sequence copolymers of lactic,glycolic, and caprolactic acids

Repeating sequence copolymers of poly(lactic‐co‐caprolactic acid) (PLCA), poly(glycolic‐co‐caprolactic acid) (PGCA), and poly(lactic‐co‐glycolic‐co‐caprolactic acid) (PLGCA) have been synthesized by polymerizing segmers with a known sequence in yields of 50–85% with M_ns ranging from 18–49 kDa. The copolymers exhibited well‐resolved NMR resonances indicating that the sequence encoded in the segmers used in their preparation is retained and that transesterification is minimal. The exact sequences allowed for unambiguous assignment of the NMR spectra, and these standards were compared with the data previously reported for random copolymers. The glass transition temperatures (T_gs) of the PLCA and PGCA copolymers were found to depend primarily on monomer ratio rather than sequence. Sequence dependent T_gs were, however, noted for the PLGCA polymers with 1:1:1 L:G:C ratios; poly LGC and poly GLC exhibited T_gs that differed by nearly 8 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Zum Nachweis von Alkaloiden in Leichentheilen

Ohne Zusammenfassung     

The effect of adsorbed atomic hydrogen on the growth of ultrathin silicon films on Ge(100) studied by positron-annihilation-induced Auger electron spectroscopy (PAES)

The effects of adsorbed atomic hydrogen on the stability of silicon films grown on a Ge(100) substrate were studied by using positron-annihilation-induced Auger electron spectroscopy (PAES) and electron-induced Auger electron spectroscopy (EAES). PAES is almost exclusively sensitive to the topmost atomic layer due to the trapping of positrons in an image potential well just outside the surface before annihilation. This surface specificity was exploited in the study of film stability and interfacial mixing during the growth of silicon on Ge(100). The PAES results show that the prior adsorption of hydrogen prevented the segregation of germanium on top of the deposited silicon, and that the hydrogen adsorption was useful in growing a thermally stable structure.     

Über die Einwirkung deso-Tolylmagnesiumbromids auf das Dilacton der Benzophenon-o-dicarbonsäure

Ohne Zusammenfassung     

Zur quantitativen Bestimmung des Zuckers auf optischem Wege

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