Search results for "Absolut"
showing 10 items of 551 documents
Assignment of the Absolute Configuration and Total Synthesis of (+)-Caripyrin
2014
The antifungal secondary metabolite (+)-caripyrin was studied by vibrational circular dichroism spectroscopy. Analysis of the recorded data, with the Boltzmann weighted-average of the spectra calculated at the B3LYP/6-311G(d,p) level of theory for all relevant conformers, unequivocally proved the (R,R)-configuration for the dextrorotatory natural product. Based on this finding, a short enantioselective synthesis of (+)-caripyrin was developed.
Crystal structures and absolute configurations of dexmedetomidine and its tosyl derivative
1993
Abstract X-ray diffraction data were used to determine the absolute configuration of dexmedetomidine, a new member of a class of drugs with 4-arylalkyl-1H-imidazole structure. When the anomalous effect of the parent compound proved to be too small for determination of the absolute configuration the tosyl derivative, with the same configuration, was synthesised and used as a reference. Stability of the stereogenic center was verified by HPLC technique. The absolute configuration of the compounds is S. Complete crystal structures are reported for both compounds. Co radiation was used for measurements.
THE MINIMIZING TOTAL VARIATION FLOW WITH MEASURE INITIAL CONDITIONS
2004
In this paper we obtain existence and uniqueness of solutions for the Cauchy problem for the minimizing total variation flow when the initial condition is a Radon measure in ℝN. We study limit solutions obtained by weakly approximating the initial measure μ by functions in L1(ℝN). We are able to characterize limit solutions when the initial condition μ=h+μs, where h∈L1(ℝN)∩L∞(ℝN), and μs=αℋk⌊ S,α≥0,k is an integer and S is a k-dimensional manifold with bounded curvatures. In case k<N-1 we prove that the singular part of the solution does not move, it remains equal to μs for all t≥0. In particular, u(t)=δ0 when u(0)=δ0. In case k=N-1 we prove that the singular part of the limit solution …
Translators vs translatresses’ strategies: ethical and ideological challenges
2011
In the last few years there has been an increasing interest in the issue of gender in translation practice especially thanks to the work of feminist critics and translators who see the act of translating as an activity which involves making use not of speciously neutral, so-called objective strategies, but rather dynamic procedures and tactics which negotiate and are negotiable, open and contingent, and which never assume feminine subjectivity to be an absolute and stable category. Drawing on such premises, this work will focus on the interrelation between identity, textuality and translation in an attempt to explore the idea that gender representation in translation practice may be shaped …
Studium zum Vorgang der Wasserstoffübertragung, 50. Elektroreduktion und phasentransferkatalysierte Borhydrid-reduktion prochiraler Ketone
1978
Prochirale Carbonylverbindungen wurden in die entsprechenden sekundaren Alkohole ubergefuhrt a) durch Elektroreduktion und b) mit NaBH4, in beiden Fallen mit den gleichen Ephedriniumsalzen, und zwar fur a) als optisch aktive Leitsalze und fur b) als optisch aktive Phasentransfer-Katalysatoren. Es wurden bei der Elektroreduktion und bei der Phasentransfer-Katalyse die Ausbeuten an Carbinol (und Pinakol)3), die optische Ausbeute und die absolute Konfiguration des bevorzugt gebildeten Enantiomeren bestimmt. In der uberwiegenden Mehrzahl der untersuchten Beispiele besitzen die unter Mitwirkung optisch aktiver Ephedriniumsalze nach beiden Methoden erhaltenen Uberschusenantiomeren die entgegenges…
Relative importance of taste, texture and flavour on consumers memory for custard desserts
2006
International audience
ChemInform Abstract: Synthesis of (-)-Auricularic Acid and its C-4 Epimer. The Absolute Configuration of Auricularic Acid.
2010
Abstract A synthesis of (−)-auricularic acid (2a) starting from methyl (+)-13-oxo- podocarp-8(14)-en-19-oate (3a) and a synthesis of its C-4 epimer (2b) starting from methyl (+)-13-oxopodocarp-8(14)-en-18-oate (3b) are described. The absolute configuration of natural auricularic acid is stablished as (4R, 5S, 8S, 9R, 10S, 14S).
The Mathematicians’ Happy Hunting Ground: Einstein’s General Theory of Relativity
2004
There is hardly any doubt that for physics special relativity theory is of much greater consequence than the general theory. The reverse situation prevails with respect to mathematics: there special relativity theory had comparatively little, general relativity theory very considerable, influence, above all upon the development of a general scheme for differential geometry. —Hermann Weyl, “Relativity as a Stimulus to Mathematical Research,” pp. 536–537.
Association of Thyroid Function Test Abnormalities and Thyroid Autoimmunity With Preterm Birth A Systematic Review and Meta-analysis
2019
Preterm birth complicates 5% to 15% of births worldwide, and although it is the most important direct cause of morbidity and mortality in children younger than 5 years, no known risk factors can be identified in the majority of cases. However, overt hypothyroidism and hyperthyroidism during pregnancy are well-known risk factors for preterm birth, and as such, the purpose of this study was to assess whether thyroid function test abnormalities and thyroid peroxidase (TPO) antibody positivity were associated with preterm birth. The study conducted a systematic review on the association of thyroid function or autoimmunity with preterm birth published from database inception to March 18, 2018, w…
Investigation of Tinnitus Patients in Italy: Clinical and Audiological Characteristics
2010
Objective. 312 tinnitus sufferers were studied in order to analyze: the clinical characteristics of tinnitus; the presence of tinnitus-age correlation and tinnitus-hearing loss correlation; the impact of tinnitus on subjects' life and where possible the etiological/predisposing factors of tinnitus.Results. There is a slight predominance of males. The highest percentage of tinnitus results in the decades 61–70. Of the tinnitus sufferers, 197 (63.14%) have a hearing deficit (light hearing loss in 37.18% of cases). The hearing impairment results of sensorineural type in 74.62% and limited to the high frequencies in 58.50%. The tinnitus is referred as unilateral in 59.93%, a pure tone in 66.99%…