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71.
Verena Bögelein 《Annali di Matematica Pura ed Applicata》2009,188(1):61-122
In the present paper we provide a broad survey of the regularity theory for non-differentiable higher order parabolic systems
of the type
Initially, we prove a partial regularity result with the method of A-polycaloric approximation, which is a parabolic analogue of the harmonic approximation lemma of De Giorgi. Moreover, we prove
better estimates for the maximal parabolic Hausdorff-dimension of the singular set of weak solutions, using fractional parabolic
Sobolev spaces. Thereby, we also consider different situations, which yield a better dimension reduction result, including
the low dimensional case and coefficients A(z, D
m
u), independent of the lower order derivatives of u.
相似文献
72.
The study of interfacial properties in the marine environment is important for the understanding of air-sea gas exchange processes, especially with respect to the behaviour of entrained air bubbles. Seawater contains surfactant material, much of which is thought to origin from the exudation of dissolved organic material (DOM) by phytoplankton. This study aims at investigating the influence of different phytoplankton species on the surface shear viscosity of an air-water interface. Measurements of surface shear viscosity were carried out with the ISR1 interfacial shear rheometer. Surface shear viscosities of stock cultures of Phaeocystis sp., Thalassiosira rotula, Thalassiosira punctigera and Nitzschia closterium as well as of F/2 nutrient medium and seawater were measured. The surface shear viscosity of N. closterium was investigated during different stages of its growth as well as for an unfiltered stock culture sample and its filtrate. Results reveal that the influence of phytoplankton on the surface shear viscosity is species specific. An increase in surface shear viscosity occurred for the N. closterium stock culture only. The remaining cultures showed similar behaviour to F/2 nutrient medium. The increase of surface shear viscosity during the growth of N. closterium occurred mainly during the exponential growth phase. The increases in surface shear viscosity depend on the presence of phytoplankton cells in the sample. The formation of compact mechanical structures at the air-water interface originating from the aggregation of DOM released by N. closterium as a cause for the observed increases in surface shear viscosity is discussed. 相似文献
73.
Thomas Braun Verena Schorlemer Beate Neumann Hans-Georg Stammler 《Journal of fluorine chemistry》2006,127(3):367-372
[PdMe2(dcpm)] (1) reacts with 2,4,6-trifluoropyrimidine in the presence of water to give the palladium derivative [PdMe{4-C4N2F2H(O)}(dcpm)] (2). When additional triethylamine is present complex [PdMe(2-OC4N2F2H)(dcpm)] (4) in addition to 2 is formed. Compound 2 converts slowly into the binuclear complex [Pd{4-C4N2F2H(O)}(μ-dcpm)]2 (5). The molecular structure of 5 was determined by X-ray crystallography. The palladium-palladium distance is 2.5898(3) Å. 相似文献
74.
Franziska Doll Annette Buntz Anne‐Katrin Späte Verena F. Schart Alexander Timper Waldemar Schrimpf Prof. Dr. Christof R. Hauck Prof. Dr. Andreas Zumbusch Prof. Dr. Valentin Wittmann 《Angewandte Chemie (International ed. in English)》2016,55(6):2262-2266
Protein glycosylation is a ubiquitous post‐translational modification that is involved in the regulation of many aspects of protein function. In order to uncover the biological roles of this modification, imaging the glycosylation state of specific proteins within living cells would be of fundamental importance. To date, however, this has not been achieved. Herein, we demonstrate protein‐specific detection of the glycosylation of the intracellular proteins OGT, Foxo1, p53, and Akt1 in living cells. Our generally applicable approach relies on Diels–Alder chemistry to fluorescently label intracellular carbohydrates through metabolic engineering. The target proteins are tagged with enhanced green fluorescent protein (EGFP). Förster resonance energy transfer (FRET) between the EGFP and the glycan‐anchored fluorophore is detected with high contrast even in presence of a large excess of acceptor fluorophores by fluorescence lifetime imaging microscopy (FLIM). 相似文献
75.
V Gierz J Melomedov C Förster C Deißler F Rominger D Kunz K Heinze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(34):10677-10688
Coupling of uronium salts with in situ generated N-heterocyclic carbenes provides straightforward access to symmetrical [4](2+) and unsymmetrical bis-imidazolium salts [6](2+) and [9](2+) . As indicated by cyclic and square-wave voltammetry, [6](2+) and [9](2+) can be (irreversibly) reduced by one electron. The initially formed radicals [6](.+) and [9](.+) undergo further reactions, which were probed by EPR spectroscopy and density functional calculations. The final products of the two-electron reduction are the two carbenes. Upon irradiation with UV light both [6](2+) and [9](2+) emit at room temperature in solution but with dramatically different characteristics. The different fluorescence behavior is analyzed by emission spectroscopy and interpreted by using time-dependent density functional calculations as largely due to different excited-state dynamics of [6](2+) and [9](2+) . The geometries of both radicals [6](.+) and [9](.+) and excited states {[6](2+) }* and {[9](2+) }* are substantially different from those of the parent ground-state molecules. 相似文献
76.
M Albrecht Y Shang K Hasui V Gossen G Raabe K Tahara Y Tobe 《Dalton transactions (Cambridge, England : 2003)》2012,41(31):9316-9322
Triangular triscatechol ligands are prepared in facile reaction sequences. The catechol units are either bound to the triangular backbone through their 3- or 4-position. With titanium(IV) ions, the ligands form metallosupramolecular M(4)L(4) tetrahedra which are characterized by ESI MS and proton NMR. Quantum-chemical calculations reveal that connectivity at the catechol in the 3-position results in highly condensed structures while attachment in the 4-position affords container molecules providing huge internal cavities. 相似文献
77.
Böhrsch V Mathew T Zieringer M Vallée MR Artner LM Dernedde J Haag R Hackenberger CP 《Organic & biomolecular chemistry》2012,10(30):6211-6216
In this paper we present the synthesis of glyco-phosphoramidate conjugates as easily accessible analogs of glyco-phosphorous esters via the Staudinger-phosphite reaction. This protocol takes advantage of synthetically accessible symmetrical carbohydrate phosphites in good overall yields, in which ethylene or propylene linkers can be introduced between phosphorous and galactose or lactose moieties. The phosphites were finally applied for the chemoselective reaction with azido-peptides and polyazido(poly)glycerols. 相似文献
78.
Plumeré N Ruff A Speiser B Feldmann V Mayer HA 《Journal of colloid and interface science》2012,368(1):208-219
The synthesis of Stöber silica particles as basis for redox modifications is optimized for desired properties, in particular diameter in a wide sub-micrometer range, spherical shape, monodispersity, the absence of porosity, and aggregation free isolability for characterization and later covalent modification. The materials are characterized by SEM, DLS, nitrogen sorption isotherms, helium as well as Gay-Lussac (water) pycnometry, and DRIFT spectroscopy. Particles with diameters between approximately 50 and 800 nm are obtained by varying the concentrations of the reagents and reactants, the type of solvent as well as the temperature. The use of high water concentrations and post-synthetic calcination at 600 °C results in silica particles that can be considered as nonporous with respect to the size of the active molecules to be immobilized. The effect of reaction temperature on size distribution is identified. Low polydispersity is achieved by performing the reaction in a temperature range in which a change in temperature has only a weak or no effect on the final particle diameter. Upon optimization of the sol–gel process, the shape of the particles is still spherical. The agreement between experimental and geometric data is within the expected precision of the characterization techniques. 相似文献
79.
80.
G. Resch 《Fresenius' Journal of Analytical Chemistry》1985,320(5):463-469
Zusammenfassung Bei der Erzeugung von Strom, Dampf und Fernwärme sowie der Abfuhr industrieller Prozeß-wärme durch Kühlsysteme stehen die metallischen Strukturwerkstoffe in Wechselwirkung mit dem Medium Wasser-Haltbarkeit, Verfügbarkeit und Wirkungsgrad solcher Betriebsanlagen hängen entscheidend davon ab, ob es durch Wasseraufbereitung und Wasserbehandlung gelingt, Ablagerungen von Wasserinhaltsstoffen und Korrosion in Grenzen zu halten.Die den technischen Erfordernissen genügende Analyse des Mediums Wasser ist zu einem unentbehrlichen Bestandteil aller Strategien zur Schadensverhütung geworden. Dabei kommt der Anionenanalyse eine besondere Bedeutung zu, da einige Anionen, wie z. B. Chlorid und Sulfat, die Korrosion begünstigen und andere in Gegenwart bestimmter Kationen zu schwerlöslichen Ablagerungen führen.
Vortrag anläßlich des Symposiums Anorganische Anionenanalytik, Regensburg, 19.–21. 9. 1984 相似文献
Anions in water of energy generating plants. Importance and analysis (review)
Summary With respect to the generation of electricity, steam and distant heat as well as the dissipation of industrial process heat by cooling systems, the metallic structural materials are in interaction with the medium water. Durability, availability and efficiency of such operational plants decisively depend on the possibility to limit the deposits of water content materials and corrosion by water preparation and treatment.The analysis of the medium water with complies with the technical requirements has come to be an indispensable component of all strategies to prevent damages. Anion analysis has a special importance in that regard, as some anions (e.g. chloride and sulphate) promote the corrosion and others lead to sparingly soluble deposits if certain cations are present.
Vortrag anläßlich des Symposiums Anorganische Anionenanalytik, Regensburg, 19.–21. 9. 1984 相似文献