Search results for "orbit"

Towards an Understanding of the Polar Diels–Alder Reactions of Nitrosoalkenes with Enamines: A Theoretical Study

2006

The polar Diels–Alder reactions of nitrosoalkenes with enamines have been studied using DFT methods at the B3LYP/6-31G* level of theory. These Diels–Alder reactions are characterized by a nucleophilic attack of the enamine at the conjugated position of the nitrosoalkene with concomitant ring-closure. The reactions present a total regioselectivity and a large endo selectivity. The analysis, based on the global electrophilicity of the reagents in the ground state, the natural bond orbital (NBO), and the topological analysis of the electron localization function (ELF) in the endo transition state (TS) and “halfway” along the IRC between the TS and cycloadduct, correctly explain the polar natur…

Coupled systems of non-smooth differential equations

2012

Abstract We study the geometric qualitative behavior of a class of discontinuous vector fields in four dimensions. Explicit existence conditions of one-parameter families of periodic orbits for models involving two coupled relay systems are given. We derive existence conditions of one-parameter families of periodic solutions of systems of two second order non-smooth differential equations. We also study the persistence of such periodic orbits in the case of analytic perturbations of our relay systems. These results can be seen as analogous to the Lyapunov Centre Theorem.

Strategy and suppression impairments after right lateral prefrontal and orbito-frontal lesions

2015

Regulation of the hDlg/hScrib/Hugl-1 tumour suppressor complex.

2008

The proper function of the Scribble tumour suppressor complex is dependent upon the correct localisation of its components. Previously we observed dynamic relocalisation of the hDlg component under conditions of osmotic stress. We now show that the other two components of the complex, hScrib and Hugl-1 display similar patterns of expression. We demonstrate, by shRNA ablation of hScrib expression, that hDlg and Hugl-1 are in part dependent upon hScrib for their correct localization. However under conditions of osmotic stress this apparent dependency no longer exists: hDlg and Hugl-1 localise to cell membranes independently of hScrib. We also demonstrate an interaction between the three compo…

Response of the Saccharomyces cerevisiae Mpk1 Mitogen-Activated Protein Kinase Pathway to Increases in Internal Turgor Pressure Caused by Loss of Ppz…

2004

ABSTRACT The Mpk1 pathway of Saccharomyces cerevisiae is a key determinant of cell wall integrity. A genetic link between the Mpk1 kinase and the Ppz phosphatases has been reported, but the nature of this connection was unclear. Recently, the Ppz phosphatases were shown to be regulators of K + and pH homeostasis. Here, we demonstrate that Ppz-deficient strains display increased steady-state K + levels and sensitivity to increased KCl concentrations. Given these observations and the fact that K + is the major determinant of intracellular turgor pressure, we reasoned that the connection between PPZ1 and - 2 and MPK1 was due to the combination of increased internal turgor pressure in Ppz-defic…

Molecular response of Saccharomyces cerevisiae wine and laboratory strains to high sugar stress conditions.

2010

One of the stress conditions that can affect Saccharomyces cerevisiae cells during their growth is osmotic stress. Under particular environments (for instance, during the production of alcoholic beverages) yeasts have to cope with osmotic stress caused by high sugar concentrations. Although the molecular changes and pathways involved in the response to saline or sorbitol stress are widely understood, less is known about how cells respond to high sugar concentrations. In this work we present a comprehensive study of the response to this form of stress which indicates important transcriptomic changes, especially in terms of the genes involved in both stress response and respiration, and the i…

The gas-phase chemiionization reaction between samarium and oxygen atoms: A theoretical study

2004

The Sm + O chemiionization reaction has been investigated theoretically using a method that allows for correlation and relativistic effects. Potential energy curves have been calculated for several electronic states of SmO and SmO+. Comparison with available spectroscopic and thermodynamic values for these species is reported and a mechanism for the chemiionization reaction Sm + O is proposed. The importance of spin–orbit coupling in the excited states of SmO, in allowing this chemiionization reaction to take place, has been revealed by these calculations. This paper shows the metal-plus-oxidant chemiionization reaction.

Evaluation of mycotoxins and their metabolites in human breast milk using liquid chromatography coupled to high resolution mass spectrometry

2014

Humans can be exposed to mycotoxins through the food chain. Mycotoxins are mainly found as contaminants in food and could be subsequently excreted via biological fluids such as urine or human breast milk in native or metabolised form. Since breast milk is usually supposed as the only food for new-borns, the occurrence of mycotoxins in thirty-five human milk samples was evaluated by a newly developed method based on QuEChERS extraction and UHPLC-HRMS detection. The method described here allows the detection of target mycotoxins in order to determine the quality of this initial feeding. The method has been fully validated, with recoveries ranging from 64% to 93% and relative standard deviatio…

Panel Discussion Spin and Polarization Effects in Atomic Processes

1973

In view of all the present activity on spin and polarization effects in atomic processes, perhaps the best approach to my introduction is first to summarize some of the most important recent results and to restrict myself to some typical characteristics.

Observation of novel oxygen⋯oxygen interaction in supramolecular assembly of cobalt(III) Schiff base complexes: a combined experimental and computati…

2015

Two mononuclear cobalt(III) Schiff base complexes with azide [Co(L)(N3)(L0 )] (1) and [Co(L)(N3)(L00)] (2) {where HL ¼ 1-((2-(diethylamino)ethylimino)methyl)naphthalene-2-ol, HL0 ¼ 2-hydroxy-1-naphthaldehyde and HL00 ¼ acetylacetone} have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy and single crystal X-ray diffraction studies. Both complexes show mononuclear structures with azide as terminal coligand. Structural features have been examined in detail that reveal the formation of interesting supramolecular networks generated through non-covalent forces including hydrogen bonding, C–H/H–C and C–H/p interactions. These interactions have been studied ener…