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61.
Weijin Li Song Xue Sebastian Watzele Shujin Hou Johannes Fichtner A. Lisa Semrau Liujiang Zhou Alexander Welle Aliaksandr S. Bandarenka Roland A. Fischer 《Angewandte Chemie (International ed. in English)》2020,59(14):5837-5843
Metal–organic frameworks (MOFs) and their derivatives are considered as promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which are important for many energy provision technologies, such as electrolyzers, fuel cells and some types of advanced batteries. In this work, a “strain modulation” approach has been applied through the use of surface‐mounted NiFe‐MOFs in order to design an advanced bifunctional ORR/OER electrocatalyst. The material exhibits an excellent OER activity in alkaline media, reaching an industrially relevant current density of 200 mA cm?2 at an overpotential of only ≈210 mV. It demonstrates operational long‐term stability even at a high current density of 500 mA cm?2 and exhibits the so far narrowest “overpotential window” ΔEORR‐OER of 0.69 V in 0.1 m KOH with a mass loading being two orders of magnitude lower than that of benchmark electrocatalysts. 相似文献
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E. Vogli W. Tillmann U. Selvadurai-Lassl G. Fischer J. Herper 《Applied Surface Science》2011,257(20):8550-8557
In this research work, Ti/TiAlN multilayers of various designs were deposited onto substrates pretreated by different etching procedures. The influence of multilayer design and substrate pretreatment on multilayers adhesion, hardness, wear and friction coefficients was systematically analyzed and correlated with residual stresses of these multilayers as well as with residual stresses on the coating-near substrate region, which were analyzed by synchrotron X-ray diffraction at HZB-BESSYII. These investigations show that the adhesion can be improved by a specific etching procedure, which cause increased compressive stress in the coating-near the substrate region. Additionally, it was found, that the multilayer with the thickest ceramic layers has the highest hardness and the lowest wear coefficients as well as the lowest compressive residual stress within studied multilayers. 相似文献
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Photoionization and Pyrolysis of a 1,4‐Azaborinine: Retro‐Hydroboration in the Cation and Identification of Novel Organoboron Ring Systems 下载免费PDF全文
Fabian Holzmeier Dipl.‐Chem. Melanie Lang Dr. Patrick Hemberger Dr. Andras Bodi Dipl.‐Chem. Marius Schäfer Dr. Rian D. Dewhurst Prof. Dr. Holger Braunschweig Prof. Dr. Ingo Fischer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9683-9692
The photoionization and dissociative photoionization of 1,4‐di‐tert‐butyl‐1,4‐azaborinine by means of synchrotron radiation and threshold photoelectron photoion coincidence spectroscopy is reported. The ionization energy of the compound was determined to be 7.89 eV. Several low‐lying electronically excited states in the cation were identified. The various pathways for dissociative photoionization were modeled by statistical theory, and appearance energies AE0K were obtained. The loss of isobutene in a retro‐hydroboration reaction is the dominant pathway, which proceeds with a reverse barrier. Pyrolysis of the parent compound in a chemical reactor leads to the generation of several yet unobserved boron compounds. The ionization energies of the C4H6BN isomers 1,2‐ and 1,4‐dihydro‐1,4‐azaborinine and the C3H6BN isomer 1,2‐dihydro‐1,3‐azaborole were determined from threshold photoelectron spectra. 相似文献
66.
Selective Uptake of Cylindrical Poly(2‐Oxazoline) Brush‐AntiDEC205 Antibody‐OVA Antigen Conjugates into DEC‐Positive Dendritic Cells and Subsequent T‐Cell Activation 下载免费PDF全文
Dr. Jasmin Bühler Sabine Gietzen Dr. Anika Reuter Cinja Kappel Dr. Karl Fischer Sandra Decker David Schäffel Dr. Kaloian Koynov Dr. Matthias Bros Ingrid Tubbe Dr. Stephan Grabbe Dr. Manfred Schmidt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12405-12410
To achieve specific cell targeting by various receptors for oligosaccharides or antibodies, a carrier must not be taken up by any of the very many different cells and needs functional groups prone to clean conjugation chemistry to derive well‐defined structures with a high biological specificity. A polymeric nanocarrier is presented that consists of a cylindrical brush polymer with poly‐2‐oxazoline side chains carrying an azide functional group on each of the many side chain ends. After click conjugation of dye and an anti‐DEC205 antibody to the periphery of the cylindrical brush polymer, antibody‐mediated specific binding and uptake into DEC205+‐positive mouse bone marrow‐derived dendritic cells (BMDC) was observed, whereas binding and uptake by DEC205? negative BMDC and non‐DC was essentially absent. Additional conjugation of an antigen peptide yielded a multifunctional polymer structure with a much stronger antigen‐specific T‐cell stimulatory capacity of pretreated BMDC than application of antigen or polymer–antigen conjugate. 相似文献
67.
Kay Hettrich Manfred Pinnow Bert Volkert Lars Passauer Steffen Fischer 《Cellulose (London, England)》2014,21(4):2479-2488
Novel nanoscaled cellulose particles were prepared using high-pressure homogenization of aqueous media contenting treated cellulose samples in a Microfluidizer® processor (MF). Here, we present the generation of spherical cellulose nanoparticles as an extension of previously published reports of nano fibrillated cellulose. Although MF treatment of unmodified cellulose yields nanofibrils which are reported in several publications, in the current work different kinds of pretreatments were proven to be necessary to obtain spherical structured cellulose nanoparticles. One such treatment may be the decrystallization of cellulose regenerating it from N-methylmorpholine-N-oxid-monohydrate (NMMNO*H2O). Nanocellulose was then obtained by a subsequent high-pressure mechanical treatment of the precipitate in aqueous dispersion. Decrystallization was also realized by grinding cellulose in a planetary ball mill. The resulting amorphous intermediates were characterized by Raman spectroscopy. Another approach tested was hydrolysis and subsequent mechanical treatment using an Ultra-Turrax® and MF. Another alternative was given by the mechanical treatment of aqueous dispersions of low substituted cellulose derivatives such as carboxymethyl cellulose and oxidized cellulose without any further hydrolysis. 相似文献
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The reactions of 5‐nitriminotetrazole ( 4 ) with 1‐methyl‐5‐aminotetrazole ( 2 ) as well as 2‐methyl‐5‐aminotetrazole ( 3 ) were investigated. In the first reaction 2 was protonated yielding 1‐methyl‐5‐aminotetrazolium 5‐nitrimino‐1H‐tetrazolate monohydrate ( 7 ). In the latter case no protonation could be observed and a co‐crystallization of 5‐nitraminotetrazole and 2‐methyl‐5‐aminotetrazole was obtained. In this compound a new tautomer of 4 could be found. Both products were determined by low temperature single crystal X‐ray diffraction, IR, Raman and multinuclear (1H, 13C, 15N) NMR spectroscopy, elemental analysis as well as differential scanning calorimetry. In addition the heats of formation were calculated using experimentally obtained heats of combustion. With these and the X‐ray densities several detonation parameter were computed using the EXPLO5 software. In addition the sensitivities towards impact, friction and electrostatic discharge were determined. Further, two crystal structures of the important starting materials in energetic research 5‐nitriminotetrazole monohydrate ( 4 ·H2O) and 1‐methyl‐5‐nitriminotetrazolemonohydrate ( 5 ·H2O) are presented and compared with the water‐free compounds. The heats of formation of 4 , 4 ·H2O, 5 , 5 ·H2O have been calculated by the atomization method using the CBS basis set. Inclusion of crystal water decrease heats of formation about 265 kJ mol?1. Also the influence of crystal water on sensitivities (impact, friction, electrostatic discharge) but also performance is discussed. 相似文献
70.