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41.
Philipp AA Meyer MR Wissenbach DK Weber AA Zoerntlein SW Zweipfenning PG Maurer HH 《Analytical and bioanalytical chemistry》2011,400(1):127-135
The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton,
a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine (SC). The aim of this study was to
develop a full-scan gas chromatography–mass spectrometry procedure for monitoring kratom or Krypton intake in urine after enzymatic cleavage of conjugates, solid-phase extraction, and trimethylsilylation. With
use of reconstructed mass chromatography with the ions m/z 271, 286, 329, 344, 470, 526, 528, and 586, the presence of MG, 16-carboxy-MG, 9-O-demethyl-MG, and/or 9-O-demethyl-16-carboxy-MG could be indicated, and in case of Krypton, with m/z 58, 84, 116, 142, 303, 361, 393, and 451, the additional presence of ODT and its nor metabolite could be indicated. Compounds
were identified by comparison with their respective reference spectra. Depending on the plant type, dose, administration route,
and/or sampling time, further metabolites of MG, PAY, SG, and SC could be detected. The limits of detection (signal-to-noise
ratio of 3) were 100 ng/ml for the parent alkaloids and 50 ng/ml for ODT. As mainly metabolites of the kratom alkaloids were detected in urine, the detectability of kratom was tested successfully using rat urine after administration of a common user’s dose of MG. As the metabolism in humans was
similar, this procedure should be suitable to prove an intake of kratom or Krypton. 相似文献
42.
Anika Katzfuß Katica Krajinovic Andreas Chromik Jochen Kerres 《Journal of polymer science. Part A, Polymer chemistry》2011,49(8):1919-1927
A partially fluorinated and sulfonated poly(arylene sulfone) (SPSO) was successfully synthesized via nucleophilic polycondensation of 2,2‐bis(4‐fluorophenyl)hexafluoro‐propane with 4,4′‐thiobisbenzenethiol (TBBT). In a second step, the prepared poly(arylene sulfide) was oxidized to SPSO. The polymer was blended with the polybenzimidazole PBIOO® to obtain a mechanically stable membrane. This film was compared with other polymer blends, which were synthesized in our group in the last years. We were especially interested in the influence of different bridging groups such as ether, ketone, and sulfone groups. The affect on properties such as water uptake (WU), thermal stability, proton conductivity, and oxidative stability were analyzed in this work. Additionally, the blend membranes were characterized by gel permeation chromatography. The novel SPSO blend shows a high molecular weight, and its blend membrane with PBIOO has an excellent onset of ? SO3H group splitting‐off temperature (Tonset) of 334 °C. The proton conductivity amounts to 0.11 S cm?1, and the water uptake reaches 30%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
43.
Nicole Kroll Ina Speckmann Marc Schoknecht Jana Gülzow Marek Diekmann Johannes Pfrommer Anika Stritt Maria Schlangen Andreas Grohmann Gerald Hrner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13606-13612
Formation of the O?O bond is considered the critical step in oxidative water cleavage to produce dioxygen. High‐valent metal complexes with terminal oxo (oxido) ligands are commonly regarded as instrumental for oxygen evolution, but direct experimental evidence is lacking. Herein, we describe the formation of the O?O bond in solution, from non‐heme, N5‐coordinate oxoiron(IV) species. Oxygen evolution from oxoiron(IV) is instantaneous once meta‐chloroperbenzoic acid is administered in excess. Oxygen‐isotope labeling reveals two sources of dioxygen, pointing to mechanistic branching between HAT (hydrogen atom transfer)‐initiated free‐radical pathways of the peroxides, which are typical of catalase‐like reactivity, and iron‐borne O?O coupling, which is unprecedented for non‐heme/peroxide systems. Interpretation in terms of [FeIV(O)] and [FeV(O)] being the resting and active principles of the O?O coupling, respectively, concurs with fundamental mechanistic ideas of (electro‐) chemical O?O coupling in water oxidation catalysis (WOC), indicating that central mechanistic motifs of WOC can be mimicked in a catalase/peroxidase setting. 相似文献
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45.
The paper deals with the numerical simulation of three dimensional oscillating fluid flow of filled and partial filled hollow spheres. We use a program based on finite volume method developed by the DLR. Our main interest is on the secondary flow in the middle plane. Results are presented for Newtonian fluids in dependence of different boundary conditions which are compared with analytical and experimental investigations. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
46.
Several genomic disorders are caused by an excessive number of DNA triplet repeats. We developed a DNA-templated reaction in which product formation occurs only when the number of repeats exceeds a threshold indicative for the outbreak of Chorea Huntington. The combined use of native chemical PNA ligation and auxiliary DNA probes enabled reactions on templates obtained from human genomic DNA. 相似文献
47.
Dr. Ulrike Krug Anika Gloge Dr. Peter Schmidt Dr. Johanna Becker-Baldus Dr. Frank Bernhard Dr. Anette Kaiser Cindy Montag Marcel Gauglitz Dr. Sergey A. Vishnivetskiy Prof. Dr. Vsevolod V. Gurevich Prof. Dr. Annette G. Beck-Sickinger Prof. Dr. Clemens Glaubitz Prof. Dr. Daniel Huster 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):24062-24070
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49.
Peter Coburger Pavlo Bielytskyi Darcy Williamson Dr. Evgeny Rys Dr. Anika Kreienbrink Dr. Peter Lönnecke Prof. Dr. Jörg Matysik Prof. Dr. Evamarie Hey-Hawkins 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11456-11465
Deboronation of a carborane-substituted diphosphetane 2 in toluene yielded the first nido-carboranyldiphosphetane 1 . The P−P bond in 1 can be broken via dismutation reactions with diaryl dichalcogenides yielding nido-carboranyl bis-phosphanes that were not accessible via established synthetic protocols. Additionally, transition metal complexes of 1 could be isolated including one coordination polymer. Notably, when the deboronation of 2 is carried out in ethanol, unprecedented nido-carborane-substituted secondary bis-phosphane monoxides ( 3 , 4 ) are obtained. These compounds are interesting starting materials for further reactivity studies due to their P−H bonds. Experimental findings are supported by DFT calculations including the calculation of reaction mechanisms and NMR spectroscopic parameters. 相似文献
50.
A Kreienbrink P Lönnecke M Findeisen E Hey-Hawkins 《Chemical communications (Cambridge, England)》2012,48(75):9385-9387
Carbaborane-substituted 1,2-diphosphetane reacts with elemental lithium and hydrogen chloride to give exclusively secondary mono- and bis(phosphino)carbaboranes. The latter reacts with two equivalents of formaldehyde and one equivalent of aniline to give a carbaborane-substituted 1-aza-3,6-diphosphepane. 相似文献