Search results for "Triple"
showing 10 items of 506 documents
Implementation of transition moments between excited states in the approximate coupled-cluster singles and doubles model
2008
An implementation of transition moments between excited states for the approximate coupled-cluster singles and doubles model (CC2) using the resolution of the identity (RI) approximation is reported. The accuracy of the RI approximation is analyzed for a testset of 7 molecules and 76 transitions. The RI error is found to be very small for both transition moments and oscillator strengths. Furthermore, the performance of the CC2 model in comparison with coupled-cluster singles and doubles (CCSD) is studied for 40 transitions of the same testset, yielding deviations of about 12% for the transition moments and 24% for the oscillator strengths. In addition, for 13 transitions of the testset the …
Topochemical Reactions of Monomers with Conjugated Triple-Bonds VII Mechanism of Transition from Monomer to Polymer Phase During Solid-State Polymeri…
1972
The lattice-controlled solid-state polymerisation of three different modifications of 2,4-hexadiin-1,6-diol-bis(phenylurethane) was investigated by X-ray and optical methods. The polymerisation is a homogeneous reaction. The polymer grows in the form of single chains within the crystal of the monomer. The chains extend along a definite crystallographic direction. Monomer and polymer are isomorphous and monomer-polymer single crystals of various compositions are obtained up to a quantitative conversion in the case of modification I or III. Phase separation into a mesomorphic polymer and oriented monomer phase was observed on annealing partially polymerised single-crystals of modification II …
Theoretical Determination of the Singlet → Singlet and Singlet → Triplet Electronic Spectra, Lowest Ionization Potentials, and Electron Affinity of C…
2003
The singlet → singlet and singlet → triplet electronic spectra of cycloocta-1,3,5,7-tetraene are studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbitals (ANOs) basis sets. The observed dipole-allowed features at 4.43, 6.02, and 6.42 eV and the spin-forbidden singlet → triplet bands with maxima at 3.05, 4.05, and 4.84 eV (Frueholz, R. P.; Kuppermann, A. J. Chem. Phys. 1978, 69, 3614) are assigned as the transitions 1 1 A 1 → 1 1 A 2 , 1 1 A 1 → 2 1 B 2 (3p z ), 1 1 A 1 → 3 1 E, and 1 1 A 1 - 1 3 A 2 , 1 1 A 1 → 1 3 E, 1 1 A 1 → 1 3 B 1 , respectively. The lowest (3s) Rydberg singlet and triplet states are placed at 5.58 (2 1 A 1 ) and…
Impact des allocations en ressources sur l'efficacité des écoles primaires en Côte d'Ivoire
2011
The quality of primary education in Côte d'Ivoire has deteriorated sharply over the past three decades. This situation is the result of an approximate management of the education system, which is characterized by a lack of educational support, a misallocation of resources, a congestion of classrooms (42 students for a teacher in primary school) and a lack of skilled and well trained teachers. In addition, the military-political conflict in September 2002 did not allow to improve this situation; on the contrary, it has further deteriorated the situation. Thus, the aim of this thesis is first to analyze the influence of resource endowments on the effectiveness of primary schools in Cote d'Ivo…
A loop involving NRF2, miR‐29b‐1‐5p and AKT, regulates cell fate of MDA‐MB‐231 triple‐negative breast cancer cells
2019
The present study shows that nuclear factor erythroid 2-related factor 2 (NRF2) and miR-29b-1-5p are two opposite forces which could regulate the fate of MDA-MB-231 cells, the most studied triple-negative breast cancer (TNBC) cell line. We show that NRF2 activation stimulates cell growth and markedly reduces reactive oxygen species (ROS) generation, whereas miR-29b-1-5p overexpression increases ROS generation and reduces cell proliferation. Moreover, NRF2 downregulates miR-29b-1-5p expression, whereas miR-29b-1-5p overexpression decreases p-AKT and p-NRF2. Furthermore, miR-29b-1-5p overexpression induces both inhibition of DNA N-methyltransferases (DNMT1, DNMT3A, and DNMT3B) expression and …
Experimental and theoretical studies on thymine photodimerization mediated by oxidatively generated DNA lesions and epigenetic intermediates.
2020
[EN] Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidatively generated lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer th…
Determination of amitraz and its transformation products in pears by ethyl acetate extraction and liquid chromatography-tandem mass spectrometry.
2008
A method has been developed for identification and quantification of the acaricide amitraz and its transformation products, 2,4-dimethylaniline (DMA), 2,4-dimethylformamidine (DMF) and N-2,4-dimethylphenyl-N-methylformamidine (DMPF) in pears. The analytes were extracted using ethyl acetate and anhydrous sodium sulphate. Analysis was performed by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using a triple quadrupole (QqQ) instrument. Two precursor-product ion transitions were monitored for each compound in the selected reaction monitoring (SRM) mode. The method was validated with pears taken from the orchard before the amitraz treatment …
Optimization of LC–MS/MS using triple quadrupole mass analyzer for the simultaneous analysis of carbosulfan and its main metabolites in oranges
2006
This paper describes an analytical method involving a simple solvent extraction for the simultaneous liquid chromatography coupled to quadrupole tandem mass spectrometry (LC-MS/MS) determination of carbosulfan, its most toxic metabolite--carbofuran--, and its other main metabolites--3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenolcarbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran and dibutylamine--in oranges. Chromatography was performed on a Zorbax Bonus-RP (150 mm x 2.1 mm, 5 microm). The mobile phase was a ternary gradient water-methanol-acetonitrile with 1.0 mM ammonium acetate at flow rate of 0.2 ml min(-1). The LC separation and MS/MS optimization were studied to selec…
Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry to identify contaminants in water: an insight on environment…
2013
Ultra-high pressure liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QqTOF-MS) acquiring full scan MS data for quantification, and automatic data dependent information product ion spectra (IDA-MS/MS) without any predefinition of the ions by the user was checked for identifying organic contaminants in water samples. The use of a database with more than 2000 compounds achieved high confidence results for a wide number of contaminants based upon retention time, accurate mass, isotopic pattern and MS/MS library searching. More than 20 contaminants, mostly pharmaceuticals, but also mycotoxins and polyphenols were unambiguously identified. Furthermore, the combination of s…
Identification of unknown pesticides in fruits using ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry
2007
Abstract Ultra-high-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC-QqTOF-MS) is an emerging technique offering more rapid and efficient separation, as well as the possibility to obtain accurate mass measurement and tandem mass spectrometry (MS/MS). This paper deals with the use of UPLC-QqTOF-MS to identify the pesticide residues present in complex pear extracts. Carbendazim, imazalil, and ethoxyquin were successfully identified because of the accurate mass determination of their protonated molecule and their major fragments in the product ion mass spectra. A few plastic and latex additives were also found, most of them probably coming from the packaging …