Search results for "DF"
showing 10 items of 1699 documents
FTIR matrix isolation and theoretical studies of glycolic acid dimers
2018
Glycolic acid (GA) dimers were studied in low temperature argon matrices by means of FTIR spectroscopy. Experimentally, the dimers were produced when monomeric glycolic acid molecules were thermally mobilized upon annealing of argon matrices at 25–35 K. The experimental spectra observed upon annealing indicate the presence of three different dimer structures. Computationally, MP2 and DFT calculations were used to study the potential dimer species in order to scrutinize the possible dimer structures, their energetics and their spectral features. Altogether 27 local minima were found for dimer structures for the three lowest conformers of glycolic acid considered based on previous studies on …
Synthesis of Unexpected Dimethyl 2-(4-Chlorophenyl)-2,3-dihydropyrrolo[2,1-a]isoquinoline-1,3-dicarboxylate via Hydrolysis/Cycloaddition/Elimination …
2021
Hydrolysis/[3 + 2] cycloaddition/elimination cascades employed for the synthesis of unexpected tricyclic compound derived from isoquinoline. Reaction of ethylene derivative 1 with the isoquinoline ester iminium ion 2 in alkaline medium (MeOH/NEt3) under reflux for 1 h resulted in the formation of the fused pyrrolo[2,1-a]isoquinoline derivative 3. Its structure was elucidated by X-ray single crystal and other spectrophotometric tools. Hirshfeld calculations for 3 and its crystal structure analysis revealed the importance of the short O…H (19.1%) contacts and the relatively long H…C (17.1%), Cl…H (10.6%) and C…C (6.1%) interactions in the molecular packing. DFT calculations were used to compu…
N-Heterocyclic Carbene Catalyzed Quadruple Domino Reactions through α,β-Unsaturated Acyl Azolium Intermediates : Asymmetric Synthesis of Cyclopenta[c…
2018
An N‐heterocyclic carbene catalyzed domino sequence via α,β‐unsaturated acyl azolium intermediates has been developed. This strategy provides a convenient enantioselective route to functionalized tricyclic coumarin derivatives and cyclopentanes. DFT studies and control experiments were performed to gain better insight into the reaction mechanism. peerReviewed
Optimizing the SYBR green related cyanine dye structure to aim for brighter nucleic acid visualization
2022
In recent years, the studies of RNA and its use for the development of RNA based vaccines have increased drastically. Although cyanine dyes are commonly used probes for studying nucleic acids, in a wide range of applications, there is still a growing need for better and brighter dyes. To meet this demand, we have systematically studied the structure of SYBR green-related cyanine dyes to gain a deeper understanding of their interactions with biomolecules especially how they interact with nucleic acids and the structural components which makes them strongly fluorescent. Herein, five new dyes were synthesized, and their photophysical properties were evaluated. Observations of photophysical cha…
Production and extraction of astaxanthin from Phaffia rhodozyma and its biological effect on alcohol-induced renal hypoxia in Carassius auratus
2015
The effect of astaxanthin (3,3â²-dihydroxy-s-carotene-4,4â²-dione) on alcohol-induced morphological changes in Carassius auratus, as an experimental model, was determined. The yeast Phaffia rhodozyma was used as a source of astaxanthin. The animals were divided into three groups for 30 days: one group was treated with ethanol at a dose of 1.5% mixed in water, the second one with EtOH 1.5% and food enriched with astaxanthin from P. rhodozyma, and the third was a control group. After a sufficient experimental period, the samples were processed using light microscopy and evaluated by histomorphological and histochemical staining, and the data were supported by immunohistochemical analysis, u…
"Rational herding in crowdfunding, social preferences under uncertainty, and overplacement in known and unknown tasks: a behavioral approach"
2020
It has been proved in this dissertation how experimental economics continues to be a tool that, as it nourishes theoretical economics (and viceversa), it keeps producing results that are necessary to understand how to articulate social relations which, ultimately, have consequences oneconomic relations. Specifically, Chapter 1 has studied how the dissemination of new information affects crowdfunding markets and the generation of herding behaviour. Specifically, we provide evidence in that such behaviour is rational and could be well moulded through optimal choice under uncertainty with Bayesian review of beliefs. In this sense, the effect of the first sponsors on the agents# behaviour has b…
A cultural comparison of mindfulness and student performance: Evidence from university students in five countries
2021
Societal and cultural norms are important in shaping how individuals live, study, and work. Of particular interest in recent research is the role of mindfulness, defined as the ability to focus on the present moment, and how it can impact cognitive function and productivity. This study examines the relationship between scholastic achievement and mindfulness among university students in China, Finland, Germany, South Africa, and the United States. Comparisons between countries with respect to self-reported measures of mindfulness, test anxiety levels, and phone usage are analyzed. These measures are used to determine whether mindfulness affects student performance in introductory economics c…
Mākslas pasaules alūzijas Donnas Tartas romānā “The Goldfinch”
2018
Donnas Tartas romāns „The Goldfinch” kopš tā publicēšanas radījis sajūsmas vilni literatūras kritiķos un lasītājos visā pasaulē, piedzīvojot tulkojumu trīsdesmit valodās. Tomēr, izvērtējot iespējamo tulkojumu latviešu valodā, romānā attēlotā mākslas pasaule un alūzijas uz to varētu radīt ievērojamus sarežģījumus romāna tulkotājam. Tādēļ šajā darbā tiek pētītas īpašvārdu alūzijas uz mākslas pasauli, padziļināti apskatot tieši mākslas un literatūras alūzijas, un tiek izdarīti secinājumi par to iespējamo atveidi tulkojumā latviešu valodā, balstoties uz tulkošanas teorijā piedāvātajām stratēģijām un domāšanas modeļiem, ko piedāvā tādi autori kā Ritva Lepihalme, Ričards Tomass, kā arī Stīvens Ha…
Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y = Br, Cl; bdmim = 1-butyl-2,3-dime…
2014
The discrete mixed [TeBrxCl6−x]2− anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X = Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X = Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4]2− and [TeBr4Cl2]2− anions …
Compound climate extreme events threaten migratory birds’ conservation in western U.S.
2022
In a warming world, more intense and frequent compound climate extreme events pose serious challenges to biodiversity and conservation on Earth as one of the 2030 United Nations’ sustainable development goals (SDGs): “Life On Land” (SDG 15). In summer 2020, concurrent swelling wildfires and a sudden cold snap in the western U.S. killed a massive number of migratory birds. In August 2020, the hot and humid weather in response to the wildfire radiation and the oceanic evaporation could result in killing heat stress for migratory birds along the coastal shoreline, particularly in California. The heat and smoke of wildfires forced the migratory birds to abandon such feeding grounds towards inla…