Search results for "State."
showing 10 items of 8943 documents
Aparatūra “Lotoss” poliuretāna plastmasas detaļu atliešanai kosmosā
2020
1980. gadā kosmosa stacijā “Salūts” pirmoreiz kosmonautikas vēsturē tika realizēts putupoliuretāna ieguves eksperiments mikrogravitācijas apstākļos, kura rezultāta tika iegūtas jaunas atziņas par ķīmiski tehnoloģisko procesu norisi kosmosā. Kosmosā tapa Maskavas olimpisko spēļu simbola lācīša figūra. Iekārtu "Lotoss", kas pašreiz atrodas Latvijas Ķīmijas vēstures muzeja krājumā, LPSR Zinātņu Akadēmijas Koksnes ķīmijas institūtā izstrādājis latviešu ķīmiķis, ķīmijas doktors, izgudrotājs un gleznotājs Arnolds Alksnis, un tā domāta polimerizācijas reakciju pētīšanai bezsvara stāvoklī.
Application of SQMFF Vibrational Calculations to Transition States: DFT and ab Initio Study of the Kinetics of Methyl Azide and Ethyl Azide Thermoly…
1998
DFT including nonlocal corrections and ab initio calculations at MP2 and MP4 levels of theory have been performed in order to provide information concerning the mechanism of the rate limiting step of the thermal decomposition of methyl azide and ethyl azide. The chemically interesting points of the ground-state potential energy surface have been fully optimized, and a detailed normal-mode analysis for the reagents and the transition states is presented. The well-established scaled quantum mechanical force field method has been used to obtain reliable vibrational frequencies for these molecular structures. The force fields of transition states have been modified by using the scale factors co…
Role of vitreous matrix on the optical activity of Ge-doped silica
2003
Abstract We report an experimental study on the relationship between the optical activity of Ge-oxygen deficient centers and dynamic properties and conformational heterogeneity of vitreous matrix in silica. We focus our attention on the absorption band at ∼5.2 eV (B 2β ) and on the two related emissions at ∼4.2 eV (α E ) and at ∼3.1 eV (β). From the temperature dependence of B 2β band we estimate a mean energy value of 26 meV for local vibrational modes coupled to the electronic transition, suggesting that the chromophore and its surrounding have access to low frequency dynamics. From the thermal behavior of the two emissions we distinguish the two competitive relaxation processes from the …
A theory ofnonverticaltriplet energy transfer in terms of accurate potential energy surfaces: The transfer reaction from π,π* triplet donors to 1,3,5…
2004
Triplet energy transfer (TET) from aromatic donors to 1,3,5,7-cyclooctatetraene (COT) is an extreme case of "nonvertical" behavior, where the transfer rate for low-energy donors is considerably faster than that predicted for a thermally activated (Arrhenius) process. To explain the anomalous TET of COT and other molecules, a new theoretical model based on transition state theory for nonadiabatic processes is proposed here, which makes use of the adiabatic potential energy surfaces (PES) of reactants and products, as computed from high-level quantum mechanical methods, and a nonadiabatic transfer rate constant. It is shown that the rate of transfer depends on a geometrical distortion paramet…
Competitive relaxation processes of oxygen deficient centers in silica
2003
Physical review / B 67, 033202 (2003). doi:10.1103/PhysRevB.67.033202
Dynamics of spin state conversion processes in the solid state
1989
High spin (HS) ⇌ low spin (LS) conversions in transition metal complexes are nonradiative transitions between spin states. In this contribution, we present a study of the temperature and pressure dependence of the HS ⇌ LS intersystem crossing dynamics. For some iron(II) spin-crossover complexes, the rate constants were determined by line shape analysis of57Fe Mossbauer spectra. Their temperature dependence is described by an Arrhenius equation, their pressure dependence is interpreted within absolute rate theory. HS → LS conversion rates at low temperatures were determined from the relaxation of light-induced formation of HS states, monitored by optical spectroscopy. Deviations from a simpl…
Phonon coupling of non-bridging oxygen hole center with the silica environment: Temperature dependence of the 1.9 eV emission spectra
2008
Abstract We report an experimental study on the shape of the 1.9 eV emission associated with non-bridging oxygen hole centers in silica and its temperature dependence, from 4 up to 300 K, under visible and ultraviolet excitation. Our analysis points out that these defects are coupled with their environment by phonons whose contribution can be described by the single mode of mean frequency between 300–400 cm −1 and Huang–Rhys factor of ∼3. On increasing the temperature, the luminescence intensity undergoes a thermal quenching caused by non-radiative processes, its deviation from a pure Arrhenius law can be accounted for by an uniform distribution of activation energy, from 0.002 to 0.05 eV. …
Web informatīvā sistēma
2017
Kvalifikācijas darba „Web informatīvā sistēma” mērķis ir izveidot īpašumu sludinājumu publisku tīmekļa vietni, kas aizstās esošu „ArtEstate” kataloga sistēmu. Šī programmatūra nodrošinās iespēju klientiem atrast un saglabāt īpašumus pēc izvēlētajiem kritērijiem, kā arī sazināties ar uzņēmuma darbiniekiem jaunu sludinājumu pieteikšanai un konsultācijām. Darbiniekiem tiks paredzēta vienkārši lietojama sludinājumu un mājas lapas pārvaldes sistēma ar vairāku vienlaicīgu lietotāju pieslēgšanās iespēju. Izstrādes procesā tiks iegūta uzņēmumam būtiska programmatūra, kas klientiem atvieglos nekustamo īpašumu komerciālās darbības.
Horyzontalny skutek bezpośredni obowiązku zawieszenia udzielania pomocy na podstawie art. 108 ust. 3 zd. 3 TFUE
2021
Niniejsza praca odnosi się do zagadnienia skutku bezpośredniego klauzuli zawieszenia (art. 108 ust. 3 zd. 3 TFUE), mającej zastosowanie do odzyskania pomocy niezgodnej z prawem bez konieczności istnienia decyzji Komisji, wskazując, że niedawny rozwój orzecznictwa wskazuje na jej skutek horyzontalny. Nadto sytuacja beneficjenta jest poddawana ocenie z wnioskiem, że ów nie posiada podobnej pozycji procesowej, co osoba powołująca się na art. 108 ust. 3 zd. 3 TFUE. Praca odnosi się do stanu prawnego z 1.04.2021 r.
Focused Ultrasound Effects on Osteosarcoma Cell Lines
2019
MRI guided Focused Ultrasound (MRgFUS) has shown to be effective therapeutic modality for non-invasive clinical interventions in ablating of uterine fibroids, in bone metastasis palliative treatments, and in breast, liver, and prostate cancer ablation. MRgFUS combines high intensity focused ultrasound (HIFU) with MRI images for treatment planning and real time thermometry monitoring, thus enabling non-invasive ablation of tumor tissue. Although in the literature there are several studies on the Ultrasound (US) effects on cell in culture, there is no systematic evidence of the biological effect of Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) treatment on osteosarcoma cells, …