Search results for "lek"
showing 10 items of 2808 documents
Solution- and gas-phase study of binding of ammonium and bisammonium hydrocarbons to oxacalix[4]arene carboxylate
2023
Oxacalixarenes represent a distinctive class of macrocyclic compounds, which are closely related to the parent calixarene family, offering binding motifs characteristic of calixarenes and crown ethers. Nevertheless, they still lack extensive characterization in terms of molecular recognition properties and the subsequent practical applicability. We present here the results of binding studies of an oxacalix[4]arene carboxylate macrocycle toward a variety of organic ammonium cationic species. Our results show that the substituents attached to the guest ammonium compound largely influence the binding strengths of the host. Furthermore, we show that the characteristic binding pattern changes up…
UV laser induced photolysis of glycolic acid isolated in argon matrices
2021
The photochemistry of matrix-isolated glycolic acid, induced by UV light, was studied by FTIR spectroscopy and B3LYPD3/6-311++G(3df,3pd) calculations. Several decomposition pathways were found to take place upon 212 nm and 226 nm wavelengths irradiation. A number of complexes formed between photoproducts were identified, among them those of formaldehyde with water, carbon monoxide and carbon dioxide as well as the H2O-CO complexes. The structure and spectroscopic assignment of the photoproducts were made comparing the experimental results with the theoretical predictions and available literature data. The observed formation of different complexes indicates various pathways for their formati…
Encapsulation of xenon by bridged resorcinarene cages with high 129Xe NMR chemical shift and efficient exchange dynamics
2023
Functionalized cages encapsulating xenon atoms enable highly sensitive, background-free molecular imaging through a technique known as HyperCEST 129Xe MRI. Here, we introduce a class of potential biosensor cage structures based on two resorcinarene macrocycles bridged either by aliphatic carbon chains or piperazines. First-principles-based modeling predicts a high chemical shift (about 345 ppm) outside the typical experimental observation window for 129Xe encapsulated by the aliphatically bridged cage and two 129Xe resonances for the piperazine-bridged cages corresponding to single and double loading. Based on the computational predictions as well as 129Xe chemical exchange saturation trans…
Testosterone and male mating success on the black grouse leks
1996
On black grouse (Tetrao tetrix) leks females prefer dominant, viable males that have managed to acquire relatively central territories. The immunocompetence hypothesis predicts that, because high levels of testosterone are costly to the immune system, male sexual traits that are controlled by testosterone are likely to serve as reliable indicators of male health. Indeed, testosterone concentrations of black grouse males were highly variable, and strongly correlated with male mating success. This is related to the fact that males with high testosterone levels had most central territories. However, the association of testostestorone level with male mating success was not solely related to cen…
Inactivation of folylpolyglutamate synthetase Met7 results in genome instability driven by an increased dUTP/dTTP ratio
2020
AbstractThe accumulation of mutations is frequently associated with alterations in gene function leading to the onset of diseases, including cancer. Aiming to find novel genes that contribute to the stability of the genome, we screened the Saccharomyces cerevisiae deletion collection for increased mutator phenotypes. Among the identified genes, we discovered MET7, which encodes folylpolyglutamate synthetase (FPGS), an enzyme that facilitates several folate-dependent reactions including the synthesis of purines, thymidylate (dTMP) and DNA methylation. Here, we found that Met7-deficient strains show elevated mutation rates, but also increased levels of endogenous DNA damage resulting in gross…
Kritiskā domāšana, inovācija, konkurētspēja un globalizācija: rakstu krājums
2018
Rakstu krājumā apkopoti raksti, kuru sākotnējās versijas tika apspriestas LU Filozofijas un socioloģijas institūta prioritārajam projektam “Kritiskā domāšana, inovācija, konkurētspēja un globalizācija” veltīto LU 75. konferences sekciju darbā 2017. gada 14. un 15. februārī. 2017. gadā LU Filozofijas un socioloģijas institūta pētnieki darbojās šādās projekta apakštēmās: Kritiskā domāšana intelektuālajā vēsturē, mūsdienu praksēs un kultūrinovācijās un Globalizācija un migrācija: “jaunās Eiropas” modeļi. Pirmās apakštēmas svarīgākie uzdevumi bija kritiskās domāšanas konceptu apkopošana un izvērtēšana; tās vietas un iespēju noskaidrošana Eiropas intelektuālajā vēsturē, kā arī kritiskās domāšana…
Dopētu un nedopētu bismuta selenīda nanolaminātu veidošana un raksturošana
2019
Dopētu un nedopētu bismuta selenīdu nanolaminātu veidošana un raksturošana. Britāla L., zinātniskie vadītāji Dr. phys., vadošā pētniece Andžāne J., Dr. chem., asoc. prof. Erts D. Bakalaura darbs, -- lappuses, -- attēli, -- tabulas, -- literatūras avoti, -- pielikumi. Latviešu valodā. Šajā pētījumā tiek izstrādāta metode ar alvu dopētu un nedopētu Bi2Se3 ultraplānu kārtiņu, ar biezumu 10 nm, sintēzei uz grafēna virsmas. Secīgi sintezējot šādi strukturētus bismuta selenīda slāņus, uz grafēna pamatnes tiek izveidots nanolamināts, kurš sastāv no dopētām un nedopētām ultraplānām bismuta selenīda kārtiņām. Noteiktas šo nanolaminātu termoelektriskās īpašības un tos ietekmējošie faktori.
Apjomīga starpvalodu skaitļojamā leksikona izstrāde GF ietvarā
2017
Darbā tiek skatīts kā varētu veidot starpvalodu leksikonu latviešu valodai Grammatical Framework ietvarā. Pašlaik ietvarā jau ir ieviests pamata latviešu valodas atbalsts ar kura palīdzību var novērtēt tā funkcionalitāti. Tomēr nav pieejams pietiekami plašs leksikons morfoloģiskas analīzes un tulkošanas iespēju attīstīšanai un novērtēšanai. Šī darba ietvaros izstrādāts starpvalodu skaitļojamais leksikons latviešu valodai lietošanai Grammatical Framework ietvarā un aprakstīti tā veidošanas principi. Tas nodrošina aptuveni 60 tūkstoši leksēmu priekš valodas un vairāk kā 10 tūkstošu vārdu sasaisti ar abstrakto valodu tulkošanas vajadzībām.
Design of Photovoltaic System for Rural Electrification in Rwanda
2017
Master's thesis Renewable Energy ENE500 - University of Agder 2017 In this century of accelerated development in various domains, some African countries are still facing a challenge of lack of power due to its scarce in some places, where by the main source of power (generation of electricity) is hydro since thermal and fuel are still on a small scale. This problem results in less productivity and economic decline of some countries like Rwanda which is among African countries that are at a very high speed in development, the grid lines from distant places are stack and they are few compared to the need of electricity in all corners of the country, especially in rural areas whereby each hous…
Aufsätze
1800
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