Search results for "MR"
showing 10 items of 3001 documents
Anion Responsive Molecular Switch Based on a Doubly‐Strapped Calix[4]pyrrole
2022
A calix[4]pyrrole receptor bearing two proximally meso - meso linking isophthaloyl straps displays open and closed states depending on the calix[4]pyrrole conformation. In the crystal structures and in non-polar solvent, the calix[4]pyrrole adopts open 1,3-alternate conformation with straps on the sides. Anion binding triggers a closed state of the receptor providing two types of interactions with an aromatic benzoate guest: hydrogen bonds from the pyrrolic groups and π ··· π interactions from the phenyl groups of the straps. Slow exchange dynamics was observed on the NMR timescale indicating that benzoate, acetate and chloride anions, which bind with relatively low affinity get kinetically…
Adenosine A2A and A2B Receptors Differentially Modulate Keratinocyte Proliferation: Possible Deregulation in Psoriatic Epidermis
2017
Adenosine is a potent regulator of inflammation and immunity, but the role of adenosine receptors in keratinocytes remains controversial. We determined that in addition to A2B receptors, human epidermal keratinocytes also express A2A receptors, although to a lower extent. Through the use of selective adenosine receptor agonists and antagonists, we showed that physiological concentrations of adenosine activate A2B receptors in normal human keratinocytes, inducing cell cycle arrest through the increase of intracellular calcium but not through cAMP signaling. In contrast, the selective activation of A2A receptors by CGS-21680 induces keratinocyte proliferation via p38–mitogen-activated protein…
Convergent results from experimental and theoretical DFT studies of the intramolecular rearrangement of Z-hydrazones of 3-acetyl-1,2,4-oxadiazoles
2004
A combined kinetic and theoretical study of the monocyclic rearrangements of heterocycles (MRH) has been carried out. The interconversion of the Z-hydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the corresponding triazole has been experimentally investigated in dioxane/water in the pS(+) range 5.5(5)-13.9. The uncatalyzed region has been examined at the DFT level using a model system formed by the Z-hydrazone of 3-formyl-1,2,4-oxadiazole and one or two water molecules. The environmental effect of the solvent has been emulated using a continuum model (COSMO) approach. The kinetic data suggest a concerted process where the magnitude of the activation barrier is determined by the interpl…
Discriminatory Brain Processes of Native and Foreign Language in Children with and without Reading Difficulties
2022
The association between impaired speech perception and reading difficulty has been well established in native language processing, as can be observed from brain activity. However, there has been scarce investigation of whether this association extends to brain activity during foreign language processing. The relationship between reading skills and neuronal speech representation of foreign language remains unclear. In the present study, we used event-related potentials (ERPs) with high-density EEG to investigate this question. Eleven- to 13-year-old children typically developed (CTR) or with reading difficulties (RD) were tested via a passive auditory oddball paradigm containing native (Finn…
Dynamic Stabilization of the Ligand-Metal Interface in Atomically Precise Gold Nanoclusters Au68 and Au144 Protected by meta-Mercaptobenzoic Acid
2017
Ligand-stabilized, atomically precise gold nanoclusters with a metal core of a uniform size of just 1-3 nm constitute an interesting class of nanomaterials with versatile possibilities for applications due to their size-dependent properties and modifiable ligand layers. The key to extending the usability of the clusters in applications is to understand the chemical bonding in the ligand layer as a function of cluster size and ligand structure. Previously, it has been shown that monodispersed gold nanoclusters, stabilized by meta-mercaptobenzoic acid (m-MBA or 3-MBA) ligands and with sizes of 68-144 gold atoms, show ambient stability. Here we show that a combination of nuclear magnetic reson…
Single-event effects of space and atmospheric radiation on memory components
2017
Electronic memories are ubiquitous components in electronic systems: they are used to store data, and can be found in all manner of industrial, automotive, aerospace, telecommunication and entertainment systems. Memory technology has seen a constant evolution since the first practical dynamic Random- Access Memories (dynamic RAMs) were created in the late 60's. The demand for ever-increasing performance and capacity and decrease in power consumption was met thanks to a steady miniaturization of the component features: modern memory devices include elements barely a few tens of atomic layers thick and a few hundred of atomic layers wide. The side effect of this constant miniaturization was a…
Aberrant brain functional networks in type 2 diabetes mellitus: A graph theoretical and support-vector machine approach
2022
ObjectiveType 2 diabetes mellitus (T2DM) is a high risk of cognitive decline and dementia, but the underlying mechanisms are not yet clearly understood. This study aimed to explore the functional connectivity (FC) and topological properties among whole brain networks and correlations with impaired cognition and distinguish T2DM from healthy controls (HC) to identify potential biomarkers for cognition abnormalities.MethodsA total of 80 T2DM and 55 well-matched HC were recruited in this study. Subjects’ clinical data, neuropsychological tests and resting-state functional magnetic resonance imaging data were acquired. Whole-brain network FC were mapped, the topological characteristics were ana…
Colorectal cancer incidences in Lynch syndrome: a comparison of results from the prospective lynch syndrome database and the international mismatch r…
2022
Abstract Objective To compare colorectal cancer (CRC) incidences in carriers of pathogenic variants of the MMR genes in the PLSD and IMRC cohorts, of which only the former included mandatory colonoscopy surveillance for all participants. Methods CRC incidences were calculated in an intervention group comprising a cohort of confirmed carriers of pathogenic or likely pathogenic variants in mismatch repair genes (path_MMR) followed prospectively by the Prospective Lynch Syndrome Database (PLSD). All had colonoscopy surveillance, with polypectomy when polyps were identified. Comparison was made with a retrospective cohort reported by the International Mismatch Repair Consortium (IMRC). This com…
Problēmrisināšanas prasmju identificēšana vidusskolas matemātikā
2021
Problēmrisināšanas prasmju identificēšana vidusskolas matemātikā. Artūrs Ļevikins, darba vadītāja Mg. paed. Aira Kumerdanka. Darba teorētiskajā daļā ir aprakstīta komplekso uzdevumu vidusskolas matemātikā, struktūra un pazīmes, ka arī normatīvo dokumentu prasības attiecībā uz to pielietošanu mācību procesā. Darba pētnieciskajā daļā ir izstrādāts un aprobēts komplekso uzdevumu komplekts, grupējot pielietotās risināšanas metodes un izteiktākās problēmas. Darba turpinājumā ir aprakstīta atsevišķo problēmrisināšanas prasmju apguve ar snieguma līmeņa rubrikām, kā arī izstrādāts ieteikumu komplekts skolotājiem turpmākam darbam ar katru izcelto prasmi atkarībā no snieguma līmeņa. Diplomdarbs satur…
Krāsu centru spinu polarizācijas ar gaismu modelēšana dimantu kristālos
2017
Pateicoties krāsu centru dimanta kristālos struktūrai, pastāv iespēja polarizēt to spinus ar gaismu, elektrisko vai magnētisko lauku, kas var būt noderīgs, piemēram, vājo lauku detektēšanā. Darbā tika izstrādāts matemātisks modelis krāsu centra spina mijiedarbībai ar lāzera starojumu ārējā magnētiskā un mikroviļņu lauka klātbūtnē, kas palīdzēs saprast dimanta kristālos notiekošo procesu dinamiku. Modelis tika realizēts Wolfram Mathematica programmas ietvaros un pārbaudīts, variējot to parametrus, kā arī simulācijas rezultāti bija salīdzināti ar reāliem optiski detektētās magnētiskās rezonanses spektriem.