scholarly journals The Two Faces of the Guanyl Radical: Molecular Context and Behavior

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3511
Author(s):  
Chryssostomos Chatgilialoglu
Keyword(s):  
Theoretical Calculations ◽  
Complex Mechanism ◽  
Time Resolved ◽  
Tautomeric Forms ◽  
G Quadruplex ◽  
Molecular Context ◽  
The One ◽  
And Behavior ◽  
Intense Research

The guanyl radical or neutral guanine radical G(-H)• results from the loss of a hydrogen atom (H•) or an electron/proton (e–/H+) couple from the guanine structures (G). The guanyl radical exists in two tautomeric forms. As the modes of formation of the two tautomers, their relationship and reactivity at the nucleoside level are subjects of intense research and are discussed in a holistic manner, including time-resolved spectroscopies, product studies, and relevant theoretical calculations. Particular attention is given to the one-electron oxidation of the GC pair and the complex mechanism of the deprotonation vs. hydration step of GC•+ pair. The role of the two G(-H)• tautomers in single- and double-stranded oligonucleotides and the G-quadruplex, the supramolecular arrangement that attracts interest for its biological consequences, are considered. The importance of biomarkers of guanine DNA damage is also addressed.

Visualization and Time-Resolved Particle Image Velocimetry Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
David Tan ◽  
Yuanchao Li ◽  
Ian Wilkes ◽  
Rinaldo L. Miorini ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Axial Compressor ◽  
Time Resolved ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Direct Measurements ◽  
Image Velocimetry ◽  
The One ◽  
And Behavior

A new optically index matched facility has been constructed to investigate tip flows in compressor-like settings. The blades of the one and a half stage compressor have the same geometry, but lower aspect ratio as the inlet guide vanes (IGVs) and the first stage of the low-speed axial compressor (LSAC) facility at NASA Glenn. With transparent blades and casings, the new setup enables unobstructed velocity measurements at any point within the tip region and is designed to facilitate direct measurements of effects of casing treatments on the flow structure. We start with a smooth endwall casing. High speed movies of cavitation and time-resolved PIV measurements have been used to characterize the location, trajectory, and behavior of the tip leakage vortex (TLV) for two flow rates, the lower one representing prestall conditions. Results of both methods show consistent trends. As the flow rate is reduced, TLV rollup occurs further upstream, and its initial orientation becomes more circumferential. At prestall conditions, the TLV is initially aligned slightly upstream of the rotor passage, and subsequently forced downstream. Within the passage, the TLV breaks up into a large number of vortex fragments, which occupy a broad area. Consequently, the cavitation in the TLV core disappears. With decreasing flow rate, this phenomenon becomes more abrupt, occurs further upstream, and the fragments occupy a larger area.

scholarly journals Electron Holes in G-Quadruplexes: The Role of Adenine Ending Groups

2021 ◽  
Vol 22 (24) ◽  
pp. 13436
Author(s):  
Evangelos Balanikas ◽  
Lara Martinez-Fernandez ◽  
Gérard Baldacchino ◽  
Dimitra Markovitsi
Keyword(s):  
Radical Cations ◽  
Fast Process ◽  
Electron Hole ◽  
Time Resolved ◽  
Dna Structures ◽  
Quantum Chemistry Calculations ◽  
Uv Photons ◽  
Electron Holes ◽  
The One

The study deals with four-stranded DNA structures (G-Quadruplexes), known to undergo ionization upon direct absorption of low-energy UV photons. Combining quantum chemistry calculations and time-resolved absorption spectroscopy with 266 nm excitation, it focuses on the electron holes generated in tetramolecular systems with adenine groups at the ends. Our computations show that the electron hole is placed in a single guanine site, whose location depends on the position of the adenines at the 3′ or 5′ ends. This position also affects significantly the electronic absorption spectrum of (G+)● radical cations. Their decay is highly anisotropic, composed of a fast process (<2 µs), followed by a slower one occurring in ~20 µs. On the one hand, they undergo deprotonation to (G-H2)● radicals and, on the other, they give rise to a reaction product absorbing in the 300–500 nm spectral domain.

scholarly journals GABA—from Inhibition to Cognition: Emerging Concepts

2017 ◽  
Vol 24 (5) ◽  
pp. 501-515 ◽  
Author(s):  
T. Schmidt-Wilcke ◽  
E. Fuchs ◽  
K. Funke ◽  
A. Vlachos ◽  
F. Müller-Dahlhaus ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Brain Regions ◽  
Mammalian Brain ◽  
Resonance Spectroscopy ◽  
Inhibitory Neurotransmitter ◽  
Electrophysiological Properties ◽  
Potential Strategy ◽  
The One ◽  
And Behavior

Neural functioning and plasticity can be studied on different levels of organization and complexity ranging from the molecular and synaptic level to neural circuitry of whole brain networks. Across neuroscience different methods are being applied to better understand the role of various neurotransmitter systems in the evolution of perception and cognition. GABA is the main inhibitory neurotransmitter in the adult mammalian brain and, depending on the brain region, up to 25% of the total number of cortical neurons are GABAergic interneurons. At the one end of the spectrum, GABAergic neurons have been accurately described with regard to cell morphological, molecular, and electrophysiological properties; at the other end researchers try to link GABA concentrations in specific brain regions to human behavior using magnetic resonance spectroscopy. One of the main challenges of modern neuroscience currently is to integrate knowledge from highly specialized subfields at distinct biological scales into a coherent picture that bridges the gap between molecules and behavior. In the current review, recent findings from different fields of GABA research are summarized delineating a potential strategy to develop a more holistic picture of the function and role of GABA.

Visualization and Time Resolved PIV Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

2014 ◽  
Author(s):  
David Tan ◽  
Yuanchao Li ◽  
Ian Wilkes ◽  
Rinaldo L. Miorini ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Time Resolved ◽  
Piv Measurements ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Direct Measurements ◽  
The One ◽  
And Behavior ◽  
Casing Treatments

A new optically index matched facility has been constructed to investigate tip flows in compressor-like settings. The blades of the one and a half stage have the same geometry, but lower aspect ratio as the inlet guide vanes and the first stage of the LSAC facility at NASA Glenn. With transparent blades and casings, the new setup enables unobstructed velocity measurements at any point within the tip region, and is designed to facilitate direct measurements of effects of casing treatments on the flow structure. We start with a smooth endwall casing. High speed movies of cavitation and time-resolved PIV measurements have been used to characterize the location, trajectory, and behavior of the Tip Leakage Vortex (TLV) for two flow rates, the lower one representing pre-stall conditions. Results of both methods show consistent trends. As the flow rate is reduced, TLV rollup occurs further upstream, and its initial orientation becomes more circumferential. At pre-stall conditions, the TLV is initially aligned slightly upstream of the rotor passage, and subsequently forced downstream. Within the passage, the TLV breaks up into a large number of vortex fragments, which occupy a broad area. Consequently, the cavitation in the TLV core disappears. With decreasing flow rate, this phenomenon becomes more abrupt, occurs further upstream, and the fragments occupy a larger area.

Individual Differences in the Name Similarity Effect

2014 ◽  
Vol 35 (2) ◽  
pp. 111-118
Author(s):  
Daniel J. Howard ◽  
Roger A. Kerin
Keyword(s):  
Individual Differences ◽  
Impression Management ◽  
Interactive Effect ◽  
Purchase Intentions ◽  
Brand Attitude ◽  
Self Monitoring ◽  
Similarity Effect ◽  
And Behavior ◽  
Usage Context

The name similarity effect is the tendency to like people, places, and things with names similar to our own. Although many researchers have examined name similarity effects on preferences and behavior, no research to date has examined whether individual differences exist in susceptibility to those effects. This research reports the results of two experiments that examine the role of self-monitoring in moderating name similarity effects. In the first experiment, name similarity effects on brand attitude and purchase intentions were found to be stronger for respondents high, rather than low, in self-monitoring. In the second experiment, the interactive effect observed in the first study was found to be especially true in a public (vs. private) usage context. These findings are consistent with theoretical expectations of name similarity effects as an expression of egotism manifested in the image and impression management concerns of high self-monitors.

You Are the One I Want to Communicate With!

2013 ◽  
Vol 44 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Sabrina Pierucci ◽  
Olivier Klein ◽  
Andrea Carnaghi
Keyword(s):  
Memory Bias ◽  
Shared Reality ◽  
Communication Partner ◽  
Shared Reality Theory ◽  
The One ◽  
Study Participants

This article investigates the role of relational motives in the saying-is-believing effect ( Higgins & Rholes, 1978 ). Building on shared reality theory, we expected this effect to be most likely when communicators were motivated to “get along” with the audience. In the current study, participants were asked to describe an ambiguous target to an audience who either liked or disliked the target. The audience had been previously evaluated as a desirable vs. undesirable communication partner. Only participants who communicated with a desirable audience tuned their messages to suit their audience’s attitude toward the target. In line with predictions, they also displayed an audience-congruent memory bias in later recall.

The Formation of Intermediate Product I in a Purified System The Role of Factor IX or of its Precursor and of a Hageman Factor-PTA Fraction

1961 ◽  
Vol 6 (02) ◽  
pp. 224-234 ◽  
Author(s):  
E. T Yin ◽  
F Duckert
Keyword(s):  
Intermediate Product ◽  
Factor Ix ◽  
Assay Method ◽  
Lag Phase ◽  
Factor X ◽  
Haemophilia B ◽  
Hageman Factor ◽  
One Stage ◽  
The One

Summary1. The role of two clot promoting fractions isolated from either plasma or serum is studied in a purified system for the generation of intermediate product I in which the serum is replaced by factor X and the investigated fractions.2. Optimal generation of intermediate product I is possible in the purified system utilizing fractions devoid of factor IX one-stage activity. Prothrombin and thrombin are not necessary in this system.3. The fraction containing factor IX or its precursor, no measurable activity by the one-stage assay method, controls the yield of intermediate product I. No similar fraction can be isolated from haemophilia B plasma or serum.4. The Hageman factor — PTA fraction shortens the lag phase of intermediate product I formation and has no influence on the yield. This fraction can also be prepared from haemophilia B plasma or serum.

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