Search results for "DF"
showing 10 items of 1699 documents
Systematic conformational search analysis of the SRR and RRR epimers of 7-hydroxymatairesinol
2010
An extensive and systematic conformational search was performed on the two epimers of the natural lignan 7-hydroxymatairesinol (HMR), by means of a home-made Systematic Conformational Search Analysis (SCSA) code, designed to select more and more stable conformers through sequential geometry optimization of trial structures at increasing levels of calculation theory. In the present case, the starting molecular structures were selected by the semi-empirical AM1 method and filtered – i.e. decreased in number by choosing the more stable species – on the basis of their energy calculated by the HF method and the 6-31G(d) basis set. The geometries obtained were further refined by performing densit…
Mehr als Musik: Die sieben Dimensionen des Eurovision Song Contests
2008
"Der Eurovision Song Contest (ESC) ist der weltweit größte internationale Wettbewerb für populäre Musik und das erfolgreichste Fernsehunterhaltungsprogramm in Europa. Obwohl der ESC ursprünglich das Ziel verfolgte, die Entstehung neuer Lieder zu fördern, handelte es sich doch stets um ein von den Fernsehanstalten inszeniertes Medienereignis, das erst nachrangig musikökonomischen Zwecken dient. Für das Publikum ist der ESC auf Grund seiner Periodizität, seiner spezifischen Programmstruktur und nicht zuletzt des Zugehörigkeitsgefühls der Zuschauer, das auf Schemata nationaler und kultureller Identifikation beruht, zu einem hochgradig ritualisierten Medienereignis geworden. Seine Bedeutung geh…
Analisi quantitativa del tessuto tendineo di ratto adulto allenato
2011
Jumper's Knee
2005
A Completeness Proof for a Regular Predicate Logic with Undefined Truth Value
2023
We provide a sound and complete proof system for an extension of Kleene's ternary logic to predicates. The concept of theory is extended with, for each function symbol, a formula that specifies when the function is defined. The notion of "is defined" is extended to terms and formulas via a straightforward recursive algorithm. The "is defined" formulas are constructed so that they themselves are always defined. The completeness proof relies on the Henkin construction. For each formula, precisely one of the formula, its negation, and the negation of its "is defined" formula is true on the constructed model. Many other ternary logics in the literature can be reduced to ours. Partial functions …
Synteza i charakterystyka spektralna oktakarboksyftalocyjanin metali
2017
Przedstawiona praca dotyczy metod syntezy oktakarboksyftalocyjanin cynku, glinu i galu oraz ich charakterystyki spektralnej (spektroskopii UV-Vis), którą przestawiono zarówno z punktu widzenia eksperymentalnego, jak i teoretycznego. Opisano istniejące metody syntezy ftalocyjanin i ich modyfikacje prowadzące do uzyskania pochodnych rozpuszczalnych w wodzie, mających jako podstawniki peryferyjne osiem grup karboksylowych. Scharakteryzowano widma absorpcyjne UV- Vis typowe dla ftalocyjanin, dzięki którym można uzyskać wiele cennych informacji na temat tych kompleksów. Ponadto przeprowadzono obliczenia absorpcyjnych widm UV oktakarbosyftalocyjaniny cynku w ramach zależnej od czasu metody funkcj…
Weak Interactions between Trivalent Pnictogen Centers: Computational Analysis of Bonding in Dimers X3E···EX3 (E = Pnictogen, X = Halogen)
2009
The nature of weak interactions in dimers X3E···EX3 (E = N−Bi, X = F−I) was investigated by wave function and density functional theory (DFT)-based methods. Out of the 20 systems studied, 10 are found to be bound at the CP-MP2 and LMP2 levels of theory. Detailed partition of the interaction energy into different components revealed that dispersion is the primary force holding the dimers together but there also exists an important ionic component whose contribution increases with increasing halogen size. As expected, standard density functionals fail to describe bonding in the studied systems. However, the performance of DFT methods can be easily improved via empirical dispersion correction …
New Tetraphosphane Ligands {(X2P)2NC6H4N(PX2)2} (X = Cl, F, OMe, OC6H4OMe-o): Synthesis, Derivatization, Group 10 and 11 Metal Complexes and Catalyti…
2008
The reaction of p-phenylenediamine with excess PCl3 in the presence of pyridine affords p-C6H4[N(PCl2)2]2 (1) in good yield. Fluorination of 1 with SbF3 produces p-C6H4[N(PF2)2]2 (2). The aminotetra(phosphonites) p-C6H4[N{P(OC6H4OMe-o)2}2]2 (3) and p-C6H4[N{P(OMe)2}2]2 (4) have been prepared by reacting 1 with appropriate amount of 2-(methoxy)phenol or methanol, respectively, in the presence of triethylamine. The reactions of 3 and 4 with H2O2, elemental sulfur, or selenium afforded the tetrachalcogenides, p-C6H4[N{P(O)(OC6H4OMe-o)2}2]2 (5), p-C6H4[N{P(S)(OMe)2}2]2 (6), and p-C6H4[N{P(Se)(OMe)2}2]2 (7) in good yield. Reactions of 3 with [M(COD)Cl2] (M = Pd or Pt) (COD = cycloocta-1,5-diene)…