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721 results on '"Glaser, T"'

1. Solution-based alkyne-azide coupling on functionalized Si(001) prepared under UHV conditions

Author

Glaser, T., Meinecke, J., Länger, C., Heep, J., Koert, U., and Dürr, M.

Subjects
Condensed Matter - Materials Science
Abstract

Synthesis of organic bi-layers on silicon was realized by a combination of surface functionalization under ultra-high vacuum (UHV) conditions and solution-based click chemistry. The silicon (001) surface was prepared with a high degree of perfection in UHV and functionalized via chemoselective adsorption of ethinyl cyclopropyl cyclooctyne from the gas phase. A second organic layer was then coupled in acetonitrile via the copper-catalyzed alkyne azide click reaction. The samples were directly transferred from UHV via the vapour phase of the solvent into the solution of reactants and back to UHV without contact to ambient conditions. Each reaction step was monitored by means of X-ray photoelectron spectroscopy in UHV; the N 1s spectra clearly indicated the click reaction of the azide group in the two test molecules employed, i.e., methyl-subsituted benzylazide and azide substituted pyrene. In both cases, up to 50 - 60 % of the ethinyl cyclopropyl cyclooctyne molecules on the surface were reacted.

Published
2020

2. Click chemistry in ultra-high vacuum - tetrazine coupling with methyl enol ether covalently linked to Si(001)

Author

Glaser, T., Meinecke, J., Freund, L., Länger, C., Luy, J. -N., Tonner, R., Koert, U., and Dürr, M.

Subjects
Condensed Matter - Materials Science
Abstract

The additive-free tetrazine/enol ether click reaction was performed in ultra-high vacuum (UHV) with an enol ether group covalently linked to a silicon surface: Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate molecules were coupled to the enol ether group of a functionalized cyclooctyne which was adsorbed on the silicon (001) surface via the strained triple bond of cyclooctyne. The reaction was observed at a surface temperature of 380 K by means of X-ray photoelectron spectroscopy (XPS). No indications for tetrazine molecules which bind directly to the Si(001) surface via the nitrogen atoms were detected. A moderate energy barrier was deduced for this click reaction in vacuum by means of density functional theory based calculations, in good agreement with the experimental results. This UHV-compatible click reaction thus opens a new, flexible route for synthesizing covalently bound organic architectures.

Published
2020

9. Linking biomass production in short rotation coppice with soil protection and nature conservation

Author

Petzold R, Butler-Manning D, Feldwisch N, Glaser T, Schmidt Peter A, Denner M, and Feger K-H

Subjects
Short Rotation Coppice, Yield Estimation, Soil Protection, Nature Conservation, Land Use Planning, Forestry, SD1-669.5
Abstract

Biomass from short rotation coppice (SRC) plantations has attracted widespread attention as a component of new sustainable energy concepts. Nevertheless, as yet the surface area of SRC plantations in Europe is relatively low compared to other biomass producing land-use systems. This is somewhat incomprehensible because it has been shown that SRC systems also offer distinct ecological benefits. Therefore, greater consideration of the related ecosystem services should be incorporated into land-use planning processes. Presented in this study is a conceptual framework for the integration of soil protection and nature conservation into the spatial prioritization of areas suitable for SRC. This approach includes the development of a site-specific yield model and the identification and classification of criteria and indicators for both soil protection and nature conservation. The basic concept for planning procedures was established and tested for the State of Saxony (Germany). Existing constraints were identified, and could be attributed mainly to the availability of adequate information at different spatial scales. The regional-scale study emphasized the considerable biomass potential of SRC and the related synergy effects for soil protection and nature conservation. Future work should focus on the local (district, farm) and catchment scale and attempt to integrate additional aspects such as hydrological ecosystem services and carbon sequestration.

Published
2014
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36. Charge-Transfer-Solvent Interaction Predefines Doping Efficiency in p-Doped P3HT Films

Author

Müller, L., Nanova, D., Glaser, T., Beck, S., Pucci, A., Kast, A.K., Schröder, R.R., Mankel, E., Pingel, P., Neher, D., Kowalsky, W., Lovrincic, R., and Publica

Subjects
Institut für Physik und Astronomie
Abstract

Efficient electrical doping of organic semiconductors is a necessary prerequisite for the fabrication of high performance organic electronic devices. In this work, we study p-type doping of poly(3-hexylthiophene) (P3HT) with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ) spin-cast from two different solvents. Using electron diffraction, we find strong dopant-induced pi-pi-stacking for films from the solvent chloroform, but not from chlorobenzene. This image is confirmed and expanded by the analysis of vibrational features of P3HT and polaron absorptions using optical spectroscopy. Here, a red-shifted polaron absorption is found in doped films from chloroform, caused by a higher conjugation length of the polymer backbone. These differences result in a higher conductivity of films from chloroform. We use optical spectroscopy on the corresponding blend solutions to shed light on the origin of this effect and propose a model to explain why solutions of doped P3HT reveal more aggregation of charged molecules in chlorobenzene, whereas more order is finally observed in dried films from chloroform. Our study emphasizes the importance of solvent parameters exceeding the bare solubility of pure dopant and host material for the preparation of highly conductive doped films.

Published
2016

40. Substance P increases liver fibrosis by differential changes in senescence of cholangiocytes and hepatic stellate cells

Author

Wan, Y, Meng, F, Wu, N, Zhou, T, Venter, J, Francis, H, Kennedy, L, Glaser, T, Bernuzzi, F, Invernizzi, P, Glaser, S, Huang, Q, Alpini, G, Alpini, G., BERNUZZI, FRANCESCA VERONICA, INVERNIZZI, PIETRO, Wan, Y, Meng, F, Wu, N, Zhou, T, Venter, J, Francis, H, Kennedy, L, Glaser, T, Bernuzzi, F, Invernizzi, P, Glaser, S, Huang, Q, Alpini, G, Alpini, G., BERNUZZI, FRANCESCA VERONICA, and INVERNIZZI, PIETRO

Abstract

Substance P (SP) is involved in the proliferation of cholangiocytes in bile duct–ligated (BDL) mice and human cholangiocarcinoma growth by interacting with the neurokinin-1 receptor (NK-1R). To identify whether SP regulates liver fibrosis during cholestasis, wild-type or NK-1R knockout (NK-1R–/–) mice that received BDL or sham surgery and multidrug resistance protein 2 knockout (Mdr2–/–) mice treated with either an NK-1R antagonist (L-733,060) or saline were used. Additionally, wild-type mice were treated with SP or saline intraperitoneally. In vivo, there was increased expression of tachykinin precursor 1 (coding SP) and NK-1R in both BDL and Mdr2–/–mice compared to wild-type mice. Expression of tachykinin precursor 1 and NK-1R was significantly higher in liver samples from primary sclerosing cholangitis patients compared to healthy controls. Knockout of NK-1R decreased BDL-induced liver fibrosis, and treatment with L-733,060 resulted in decreased liver fibrosis in Mdr2–/–mice, which was shown by decreased sirius red staining, fibrosis gene and protein expression, and reduced transforming growth factor-Î21 levels in serum and cholangiocyte supernatants. Furthermore, we observed that reduced liver fibrosis in NK-1R–/–mice with BDL surgery or Mdr2–/–mice treated with L-733,060 was associated with enhanced cellular senescence of hepatic stellate cells and decreased senescence of cholangiocytes. In vitro, L-733,060 inhibited SP-induced expression of fibrotic genes in hepatic stellate cells and cholangiocytes; treatment with L-733,060 partially reversed the SP-induced decrease of senescence gene expression in cultured hepatic stellate cells and the SP-induced increase of senescence-related gene expression in cultured cholangiocytes. Conclusion: Collectively, our results demonstrate the regulatory effects of the SP/NK-1R axis on liver fibrosis through changes in cellular senescence during cholestatic liver injury. (Hepatology 2017

Published
2017

41. Cover

Author

Fekrat, Sharon, Glaser, Tanya S., and Feng, Henry L.

Published
2021

46. 8 Lens and Cataract

Author

Fekrat, Sharon, Glaser, Tanya S., and Feng, Henry L.

Published
2021

48. Foreword

Author

Fekrat, Sharon, Glaser, Tanya S., and Feng, Henry L.

Published
2021

50. Introduction

Author

Fekrat, Sharon, Glaser, Tanya S., and Feng, Henry L.

Published
2021

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