Search results for " atom"
showing 10 items of 1526 documents
Untersuchungen zum oxidativen abbau nativer cellulose, 4. Stöchiometrische verhältnisse zwischen der anzahl der entstehenden spaltstellen, dem sauers…
1978
An investigation of the kinetics of cellulose degradation confirms the scheme proposed by G. V. Schulz and Mertes with the following modifications: the fast pre-stage of the degradation is missing, because there are no faster cleaving bonds in the native cellulose; the first step of the degradation (pre-oxidation) in agreement with the above mentioned authors consists in the uptake of an oxygen atom: in the second step, the scisson proper, the scheme of Staudinger and Roos is replaced by the newer and better founded scheme of Haskins and Hogsed, assuming an alkoxy-elimination; the third step (post-oxidation) finally consists in a limited number of substeps leading to a splitting off of abou…
An efficient entry to optically active anti- and syn-beta-amino-alpha-trifluoromethyl alcohols.
2008
The reaction of chiral 5,6-dihydro-2H-1,4-oxazin-2-ones with TMSCF3 in the presence of a suitable activator leads to trifluoromethyl lactols, which can be selectively reduced to anti-beta-amino-alpha-trifluoromethyl alcohols. The corresponding syn diastereoisomers are obtained when the starting imines are reduced and the nitrogen atom is conveniently protected. In addition, a novel rearrangement of the CF3 group in the lactol intermediates has been observed. This represents a formal CF3 addition to the imine function in the starting substrates.
Synthese und biochemische Eigenschaften substituierter Phenoxy- und Anilino-1,3,5-triazine
1983
Die nucleophile Substitution eines Chloratoms in 2,4-Dichlor-6-diethylamino-1,3,5-triazin (1) durch die Hydroxyacetophenone 2a–c fuhrt zu den 2-Acetylphenoxy-4-chlor-6-diethylamino-1,3,5-triazinen 3a–c. Analog geht aus der Umsetzung von 1 mit 4-Fluoranilin (4a) das Monoanilinoderivat 5a hervor; dagegen bildet sich unter den gleichen Reaktionsbedingungen aus 1 und 2-Fluoranilin (4b) das Dianilinoderivat 5b. Strukturtyp 3 zeichnet sich durch antimykotische und Antiprotozoenwirksamkeit aus, wahrend 5 herbizide Wirkungen auszulosen vermag. Synthesis and Biochemical Properties of Substituted Phenoxy- and Anilino-1,3,5-triazines The nucleophilic substitution of one chlorine atom in 2,4-dichloro-6…
Application of pressurized fluid extraction to determine cadmium and zinc in plants
2006
Abstract A procedure for the determination of Cd and Zn in plants is proposed. The metals are extracted by pressurized fluid extraction (PFE). Operational conditions are: pressure 1500 psi, temperature 75 °C, static time 5 min, flush volume 35%, purge time 60 s, cycles 1 and 1,2-diaminocyclohexane- N , N , N ′, N ′-tetraacetic acid (CDTA) 0.01 M at pH 4.5 as extracting solution. Determination of Zn is carried out by flame atomic absorption spectroscopy and depending on the concentration level, Cd content is determined by flame or electrothermal atomic absorption spectroscopy. Certified samples of Virginia tobacco leaves, tea leaves, spinach leaves, poplar leaves, a commercial spinach sample…
Emergent ultrafast phenomena in correlated oxides and heterostructures
2017
The possibility of investigating the dynamics of solids on timescales faster than the thermalization of the internal degrees of freedom has disclosed novel non-equilibrium phenomena that have no counterpart at equilibrium. Transition metal oxides (TMOs) provide an interesting playground in which the correlations among the charges in the metal $d$-orbitals give rise to a wealth of intriguing electronic and thermodynamic properties involving the spin, charge, lattice and orbital orders. Furthermore, the physical properties of TMOs can be engineered at the atomic level, thus providing the platform to investigate the transport phenomena on timescales of the order of the intrinsic decoherence ti…
5,8,13,13-Tetrachloro-13H-dibenzo[a,i]fluorene cyclohexane hemisolvate
2019
In the crystal structure of the solvated pentacyclic title compound, C21H10Cl4·0.5C6H12, the pentacyclic chloroaromatic rings are arranged in parallel layers, with the chlorine atoms protruding from these planes. Channels orthogonal to these layers are filled with disordered cyclohexane molecules.
Intrinsic backgrounds from Rn and Kr in the XENON100 experiment
2018
In this paper, we describe the XENON100 data analyses used to assess the target-intrinsic background sources radon ([InlineMediaObject not available: see fulltext.]), thoron ([InlineMediaObject not available: see fulltext.]) and krypton ([InlineMediaObject not available: see fulltext.]). We detail the event selections of high-energy alpha particles and decay-specific delayed coincidences. We derive distributions of the individual radionuclides inside the detector and quantify their abundances during the main three science runs of the experiment over a period of ∼4years, from January 2010 to January 2014. We compare our results to external measurements of radon emanation and krypton concentr…
Resolution Characterizations of JetRIS in Mainz Using 164Dy
2022
Atoms 10(2), 57 (2022). doi:10.3390/atoms10020057
Syntheses of Trifluoroethylated N-Heterocycles from Vinyl Azides and Togni’s Reagent Involving 1,n-Hydrogen-Atom Transfer Reactions
2020
2,2,2-Trifluoroethyl-substituted 3-oxazolines, 3-thiazolines, and 5,6-dihydro-2H-1,3-oxazines have been obtained by reacting substituted vinyl azides with a combination of Togni’s reagent and substoichiometric amounts of iron(II) chloride. The results of density functional theory calculations support the proposed mechanism involving 1,n-hydrogen-atom transfer reactions. peerReviewed
Relaxion fluctuations (self-stopping relaxion) and overview of relaxion stopping mechanisms
2020
Journal of high energy physics 2005(5), 80 (2020). doi:10.1007/JHEP05(2020)080