Search results for "AA"
showing 10 items of 16992 documents
CCDC 853880: Experimental Crystal Structure Determination
2012
Related Article: L.Kaufmann, E.V.Dzyuba, F.Malberg, N.L.Low, M.Groschke, B.Brusilowskij, J.Huuskonen, K.Rissanen, B.Kirchner, C.A.Schalley|2012|Org.Biomol.Chem.|10|5954|doi:10.1039/c2ob25196e
Intermolecular oxidative dehydrogenative 3,3′-coupling of benzo[b]furans and benzo[b]thiophenes promoted by DDQ/H+: total synthesis of shandougenine B
2016
With an excess of a strong acid, 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ) is shown to promote metal-free intermolecular oxidative dehydrogenative (ODH) 3,3'-coupling of 2-aryl-benzo[b]furans and 2-aryl-benzo[b]thiophenes up to 92% yield as demonstrated with 9 substrates. Based on the analysis of oxidation potentials and molecular orbitals combined with EPR, NMR and UV-Vis observations, the studied reaction is initiated by a DDQ-substrate charge transfer complex and presumably proceeds via oxidation of the substrate into an electrophilic radical cation that further reacts with another molecule of a neutral substrate. The coupling reactivity can easily be predicted from the oxidation potent…
Synthesis, Stability and Relaxivity of TEEPO-Met: An Organic Radical as a Potential Tumour Targeting Contrast Agent for Magnetic Resonance Imaging
2018
Cancer is a widespread and life-threatening disease and its early-stage diagnosis is vital. One of the most effective, non-invasive tools in medical diagnostics is magnetic resonance imaging (MRI) with the aid of contrast agents. Contrast agents that are currently in clinical use contain metals, causing some restrictions in their use. Also, these contrast agents are mainly non-specific without any tissue targeting capabilities. Subsequently, the interest has notably increased in the research of organic, metal-free contrast agents. This study presents a new, stable organic radical, TEEPO-Met, where a radical moiety 2,2,6,6-tetraethylpiperidinoxide (TEEPO) is attached to an amino acid, methio…
Short X···N Halogen Bonds With Hexamethylenetetraamine as the Acceptor
2021
Hexamethylenetetramine (HMTA) and N-haloimides form two types of short (imide)X···N and X–X···N (X = Br, I) halogen bonds. Nucleophilic substitution or ligand-exchange reaction on the peripheral X of X–X···N with the chloride of N-chlorosuccinimide lead to Cl–X···N halogen-bonded complexes. The 1:1 complexation of HMTA and ICl manifests the shortest I···N halogen bond [2.272(5) Å] yet reported for an HMTA acceptor. Two halogen-bonded organic frameworks are prepared using 1:4 molar ratio of HMTA and N-bromosuccinimide, each with a distinct channel shape, one possessing oval and the other square grid. The variations in channel shapes are due to tridentate and tetradentate (imide)Br···N coordi…
Photochemical mineralization of terrigenous DOC to dissolved inorganic carbon in ocean
2018
When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the stu…
Extracting locations from sport and exercise-related social media messages using a neural network-based bilingual toponym recognition model
2022
Funding: This study is a part of the “Equality in suburban physical activity environments, YLLI” research project (in Finnish: Yhdenvertainen liikunnallinen lähiö, YLLI). The project is being financed by the research program about suburban in Finland “Lähiöohjelma 2020-2022” coordinated by the Ministry of Environment (grant recipient: Dr. Petteri Muukkonen). Sport and exercise contribute to health and well-being in cities. While previous research has mainly focused on activities at specific locations such as sport facilities, “informal sport” that occur at arbitrary locations across the city have been largely neglected. Such activities are more challenging to observe, but this challenge may…
Ethics in biodiversity conservation : The meaning and importance of pluralism
2022
Addressing the global extent of the current biodiversity crisis requires engaging with the existence of multiple equally legitimate values, but also with diverse ethical perspectives underpinning conceptions of right and wrong actions. However, western monist positions have mostly explicitly or implicitly directed conservation strategies by defining the space of legitimate arguments, overlooking solutions that do not fit neatly the chosen approaches. As ignoring diverse ethical positions leads to injustices and reduces the potential of conserving biodiversity, there is a need to recognise and navigate the ethical landscape. Ethical pluralism may provide opportunities to do so. However, the …
Modeling mass transfer in fracture flows with the time domain-random walk method
2019
The time domain-random walk method was developed further for simulating mass transfer in fracture flows together with matrix diffusion in surrounding porous media. Specifically, a time domain-random walk scheme was developed for numerically approximating solutions of the advection-diffusion equation when the diffusion coefficient exhibits significant spatial variation or even discontinuities. The proposed scheme relies on second-order accurate, central-difference approximations of the advective and diffusive fluxes. The scheme was verified by comparing simulated results against analytical solutions in flow configurations involving a rectangular channel connected on one side with a porous ma…
Towards sustainable servicescape : tourists’ perspectives of accommodation service attributes
2023
The study uses content analysis to identify the sustainable attributes in 678 accommodation reviews from Finnish and Russian tourists published on the Tripadvisor website and examines the sustainability perceptions of these tourist groups. The servicescape framework was applied to the structuring of the attributes indicating sustain-ability in accommodation services. The sustainable attributes highlighted in the reviews were more frequently in the physical rather than in the social servicescape factor. The tourists also reported environmental sustainability attributes more often than those related to social, cultural and economic sustainability. Overall, the sustainable attributes were perc…
New national and regional Annex I Habitat records: from #45 to #59
2022
New Italian data on the distribution of Annex I Habitats are reported in this contribution. Specifically, 8 new occurrences in Natura 2000 sites are presented and 27 new cells are added in the EEA 10 km × 10 km reference grid. The new data refer to the Italian administrative regions of Apulia, Campania, Calabria, Lazio, Tuscany, Umbria, Sardinia, and Sicily.