scholarly journals Modelling Photoionisations in Tautomeric DNA Nucleobase Derivatives 7H-Adenine and 7H-Guanine: Ultrafast Decay and Photostability

Photochem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 287-301
Author(s):  
Javier Segarra-Martí ◽  
Sara M. Nouri ◽  
Michael J. Bearpark
Keyword(s):  
Biological Sciences ◽  
Ground State ◽  
Radiation Effects ◽  
Decay Channels ◽  
Theoretical Methods ◽  
Simulation Techniques ◽  
Physical Chemical ◽  
Protection Mechanisms ◽  
Single Path ◽  
Sunlight Radiation

The study of radiation effects in DNA is a multidisciplinary endeavour, connecting the physical, chemical and biological sciences. Despite being mostly filtered by the ozone layer, sunlight radiation is still expected to (photo)ionise DNA in sizeable yields, triggering an electron removal process and the formation of potentially reactive cationic species. In this manuscript, photoionisation decay channels of important DNA tautomeric derivatives, 7H-adenine and 7H-guanine, are characterised with accurate CASSCF/XMS-CASPT2 theoretical methods. These simulation techniques place the onset of ionisation for 7H-adenine and 7H-guanine on average at 8.98 and 8.43 eV, in line with recorded experimental evidence when available. Cationic excited state decays are analysed next, uncovering effective barrierless deactivation routes for both species that are expected to decay to their (cationic) ground state on ultrafast timescales. Conical intersection topographies reveal that these photoionisation processes are facilitated by sloped single-path crossings, known to foster photostability, and which are predicted to enable the (VUV) photo-protection mechanisms present in these DNA tautomeric species.

scholarly journals Effect of Fano Resonance in photovoltaic

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Dong Sun
Keyword(s):  
Ground State ◽  
Fano Resonance ◽  
Coupling Parameter ◽  
Level System ◽  
Decay Channels ◽  
Atomic Systems ◽  
Absorption And Emission ◽  
Fano Interference ◽  
Detail Balance ◽  
Ground State Doublet

AbstractWe have shown that the Fano interference in the decay channels of a three-level system can lead to considerably different absorption and emission profiles. We found that a coherence can be built up in the ground state doublet, with strength depending on a coupling parameter that arises from the Fano interference. The coherence can in principle lead to breaking of the detail balance between the absorption and emission processes in atomic systems.

Computational Biology: Development in the Field of Medicine

2021 ◽  
Keyword(s):  
Mathematical Modeling ◽  
Computational Biology ◽  
Social Systems ◽  
Computational Simulation ◽  
Analytical Data ◽  
Theoretical Methods ◽  
Simulation Techniques

Computational biology involves the development and application of analytical-data and theoretical methods, computational simulation techniques, and mathematical modeling to the study of biological, behavioral, ecological, and social systems.

Knowledge argument

2018 ◽  
Author(s):  
Torin Alter
Keyword(s):  
Biological Sciences ◽  
Colour Vision ◽  
Thought Experiment ◽  
Natural World ◽  
Knowledge Argument ◽  
Frank Jackson ◽  
Black And White ◽  
Television Monitor ◽  
Physical Chemical ◽  
The World

The knowledge argument is an argument against physicalism, the view that the world is wholly physical. It was developed by Frank Jackson (1943–) and is based on the following thought experiment. Everything that can be known through the physical, chemical, and biological sciences – the complete physical truth – has been discovered. Mary is a brilliant scientist who is raised in a black-and-white room. She has never had colour experiences. But she learns the complete physical truth, which includes the completed science of colour vision, by reading books and watching lectures on a black-and-white television monitor. Then she leaves the room and sees colours. Jackson’s argument runs roughly as follows. When Mary leaves the room, she learns something new. She learns what it is like to see in colour. Evidently, the complete physical truth is not the complete truth about the world. Ergo, physicalism is false. Some react by denying that Mary learns anything when she leaves the room. Others react by accepting that she learns something but denying that this refutes physicalism. Still others accept the argument as sound. The ensuing discussion has led to a variety of insights about consciousness and its place in the natural world.

scholarly journals Инверсия вклада изотопа малой относительной концентрации в суммарный коэффициент поглощения смеси изотопов неона на переходе 3s-=SUB=-2-=/SUB=--2p-=SUB=-4-=/SUB=-

2019 ◽  
Vol 127 (8) ◽  
pp. 179
Author(s):  
Э.Г. Сапрыкин
Keyword(s):  
Numerical Modeling ◽  
Laser Radiation ◽  
Ground State ◽  
Optical Pumping ◽  
Discharge Plasma ◽  
Relative Concentration ◽  
Probe Laser ◽  
Decay Channels ◽  
Gas Discharge Plasma ◽  
Upper Level

AbstractAbsorption of probe laser radiation by a mixture of even isotopes of neon in a gas discharge plasma is investigated by the method of magnetic scanning of 3 s _2–2 p _4 transition. The contours of absorption lines of isotopes are resolved by means of numerical modeling. It is discovered that, upon decrease in relative concentration of one of the isotopes, its contribution to absorption is replaced by gain. The effect is found to be caused by radiative transfer of excitation energy between atoms of different kinds in the absence of a difference in level energies (the process known as optical pumping). The effect of this mechanism turned out to be substantial for the upper level transitions from which to the ground state are allowed while being absent for the lower level of the transition from which such transitions are forbidden although other decay channels are available.

scholarly journals Nature Communications: Interview with Lesley Anson

2009 ◽  
Author(s):  
Martin Fenner
Keyword(s):  
Biological Sciences ◽  
Systems Biology ◽  
Open Access ◽  
Open Access Journal ◽  
Molecular Systems ◽  
Nature Publishing Group ◽  
Physical Chemical ◽  
Publishing Group

Nature Communications is a new journal that will launch in Spring 2010. The journal will publish papers in all areas of the physical, chemical and biological sciences and is open for submissions.The Nature Publishing Group publishes one fully open access journal (Molecular Systems Biology) ...

scholarly journals Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Anton Pershin ◽  
Gergely Barcza ◽  
Örs Legeza ◽  
Adam Gali
Keyword(s):  
Ground State ◽  
Large Scale ◽  
Optical Response ◽  
Emerging Technology ◽  
Spin States ◽  
Quantum Bits ◽  
Theoretical Methods ◽  
Operational Conditions ◽  
Spin Properties ◽  
External Strain

AbstractDefect quantum bits (qubits) constitute an important emerging technology. However, it is necessary to explore new types of defects to enable large-scale applications. In this article, we examine the potential of magnesium-vacancy (MgV) in diamond to operate as a qubit by computing the key electronic- and spin properties with robust theoretical methods. We find that the electronic structure of MgV permits the coexistence of two loosely separated spin-states, where both can emerge as a ground state and be interconverted depending on the temperature and external strain. These results demonstrate a route to control the magneto-optical response of a qubit by modulating the operational conditions.

scholarly journals Translational bioadhesion research: embracing biology without tokenism

2019 ◽  
Vol 374 (1784) ◽  
pp. 20190207 ◽  
Author(s):  
J. Herbert Waite
Keyword(s):  
Biological Sciences ◽  
Biological Systems ◽  
Research Community ◽  
Theme Issue ◽  
Physical Chemical ◽  
Scientists And Engineers ◽  
Context Dependent ◽  
Fundamental Physical

Bioadhesion has attracted a sizable research community of scientists and engineers that is striving increasingly for translational outcomes in anti-fouling and bioinspired adhesion initiatives. As bioadhesion is highly context-dependent, attempts to trivialize or gloss over the fundamental physical, chemical and biological sciences involved will compromise the relevance and durability of translation. This article is part of the theme issue ‘Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.

Phonon Scattering in One-Dimensional Anharmonic Crystals and Superlattices: Analytical and Numerical Study

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Nichlas Z. Swinteck ◽  
Krishna Muralidharan ◽  
Pierre A. Deymier
Keyword(s):  
Phonon Scattering ◽  
Numerical Study ◽  
Dynamics Simulation ◽  
Spectral Energy ◽  
Multiple Time ◽  
Vibrational Modes ◽  
Decay Channels ◽  
One Dimensional ◽  
Simulation Techniques ◽  
The One

Second-order perturbation theory based on multiple time scale analysis is used to illuminate three-phonon scattering processes in the one-dimensional anharmonic monoatomic crystal. Molecular dynamics simulation techniques in conjunction with spectral energy density analyses are used to quantify phonon mode lifetime in (1) the monoatomic crystal and (2) a series of superlattice configurations. It is found that the lifetime of vibrational modes in the monoatomic crystal is inherently long, because the conditions for conservation of wave vector and frequency are pathologically difficult to satisfy. Superlattice configurations, however, offer band-folding effects, whereby the availability of phonon decay channels decreases the lifetime of the vibrational modes supported by the medium.

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