DNA damage caused by irradiation has been studied for many decades.Such studies allow us to better assess the dangers posed radiation, and increase efficiency of radiotherapies that are used combat cancer.A full description process involves multiple size time scales.It starts from interaction radiation -either photons or swift ions -with biological medium.Such interactions cause electronic excitation ionisation.The two main products ionising thus electrons radicals.Both these species can...

Reactions that can damage DNA have been simulated using a combination of molecular dynamics and density functional theory. In particular, the caused by attachment low energy electron to nucleobase. Simulations anionic single nucleotides in an aqueous environment was modeled explicitly performed. This has allowed us examine role played water molecules surround radiation mechanisms. Our simulations show hydrogen bonding protonation nucleotide significant effect on barriers strand breaking...

Modified water models with scaled charges are used to investigate solvent polarity effects on DNA structure. Several intensive molecular dynamics simulations of the EcoRI dodecamer d(CGCGAATTCGCG) in different model solvents performed. When molecule decreases, from overpolarized less polarized, experiences conformational transitions $\mathrm{\text{constrained}}\ensuremath{\rightarrow}B\text{ }\text{...

We investigate the eruption and interaction of two coronal mass ejections (CMEs) during large 2013 May 22 solar energetic particle event using multiple spacecraft observations. Two CMEs, having similar propagation directions, were found to erupt from nearby active regions (ARs), AR11748 AR11745, at ∼08:48 UT ∼13:25 UT, respectively. The second CME was faster than first CME. Using graduated cylindrical shell model, we reconstructed these CMEs that leading edge caught up with trailing a height...

The magic iron oxide cluster ${\mathrm{Fe}}_{13}{\mathrm{O}}_{8}$ is found by using a reactive laser vaporized source. From first-principles calculations, the equilibrium geometry determined to be of ${D}_{4h}$ symmetry. Comparing with ${\mathrm{Fe}}_{13}{\mathrm{O}}_{6},$ ${\mathrm{Fe}}_{12}{\mathrm{O}}_{9},$ and ${\mathrm{Fe}}_{14}{\mathrm{O}}_{7},$ has closed electron configuration in highest occupied molecular orbital (HOMO), large gap HOMO-lowest unoccupied orbital, binding energy,...

Different solvent temperatures with five kinds of counterions are used to investigate effects on the DNA microscopic structure. The dodecamer d (CGCGAATTCGCG) segment is merged into solvents and its conformation transition studied molecular dynamics simulations in detail. For simple point charge model water molecule Na+ counterions, as temperature increases from 200 K 343 K, duplex changes stiff B form a state between A form, which we define mixed (A-B) structure, double helix unwinding. To...

The physical shielding and chemical stabilizing of the low energy electron by glycine around thymine through proton transfer.

Ionizing radiation can excite the cellular medium to produce secondary electrons that subsequently cause damage DNA. The is believed occur via dissociative electron attachment (DEA). In DEA, captured by a molecule in resonant antibonding state and transient negative ion formed. If this survives against autodetachment, then bonds within may dissociate as energy transferred from electronic degrees of freedom into vibrational modes molecule. We present model for studying effect transferring...

Abstract The first human missions on Mars will likely involve several astrobiology‐driven science operations, at sites with high biosignature preservation potential. Here, we present a study of the radiation environment induced by Galactic Cosmic Rays and Solar Energetic Particles Oxia Planum, landing site European Space Agency ExoMars 2022 mission, two different locations in Mawrth Vallis, using Monte Carlo GEometry ANd Tracking 4‐based code dMEREM (detailed Martian Radiation Environment...

Based on hybrid water models, we design a series of solvent environments with different hydrogen bond strength and study the solvation NaCl in them. The microstructures dynamical behaviors solvents ion solutes are presented detail to trace correlations between mechanism ions. In process NaCl, balance competition breaking original structures formation hydration shells around ions is sensitive bonding ability water. results indicate that most ideally dissolved natural strongest effects both...

Electronic structures and stability of ${\mathrm{Se}}_{\mathit{n}}$ (n=3,4,5,6,7,8) clusters have been studied by using the discrete variational method in framework local-density approximation. Binding energy, ionization potential, affinity other electronic properties structure models Hohl et al. [Chem. Phys. Lett. 139, 540 (1987)] are presented compared with available experiments. In addition, a rectangular lattice arrangement selenium has fabricated on highly oriented pyrolytic graphite,...

Recently it has been suggested that the "twin-CME" scenario Li.etal2012 may be a very effective mechanism in causing extreme Solar Energetic Particle (SEP) events and particular Ground Level Enhancement (GLE) events. Ding.etal2013 performed statistical examination of twin-CME with total $126$ fast wide western Coronal Mass Ejections (CMEs). They found CMEs having preceding CME speed $>$ 300 $km/s$ within $9$ hours from same active region have larger probability leading to large SEP than do...

Knowledge of the electronic stopping curve for swift ions, $S_e(v)$, particularly around Bragg peak, is important understanding radiation damage. Experimentally, however, determination such feature light ions very challenging, especially in disordered systems as liquid water and biological tissue. Recent developments real-time time-dependent density functional theory (rt-TDDFT) have enabled calculation $S_e(v)$ along nm-sized trajectories. However, it still a challenge to obtain meaningful...

It has recently been suggested that large solar energetic particle (SEP) events are often caused by twin coronal mass ejections (CMEs). In the twin-CME scenario, preceding CME provides both an enhanced turbulence level and seed population at main CME-driven shock. this work, we study effect of CMEs on population. We examine event-integrated abundance iron to oxygen ratio (Fe/O) energies above 25 MeV/nuc for SEP in cycle 23. find Fe/O (normalized reference value 0.134) ≤2.0 almost all...

Starting from the energy conversion and conservation law in constant-NVE ensemble, molecular dynamics method using COMPASS force field was applied to investigate dynamic properties of graphene nanoribbons (GNRs) together with GNR-based strain sensors. The following results were obtained: (a) nonlinear response dominates behavior GNRs, their ultra-high fundamental frequencies are closely related length boundary conditions; (b) effect uniaxial tensile on GNRs is significant strongly depends...

Forbush decrease (FD) event is one of the most important short-term modulations galactic cosmic rays (GCRs) caused by intense solar activities such as interplanetary coronal mass ejection (ICME). The modulation mechanisms GCRs disturbed magnetic fields (IMF) ICME and accompanying forward shock (IP) are not clear yet. In this work, we present a one-dimensional dynamic model GCR barrier driven ICME. our model, time dependent radial diffusion coefficient rr depressed to be (r)rr (0 (r) 1) they...

The electronic stopping power ($S_e$) of water vapor (H$_2$O), hydrogen (H$_2$) and oxygen (O$_2$) gases for protons in a broad range energies, centered the Bragg peak, was calculated using real-time time-dependent density functional theory (rt-TDDFT) simulations with Gaussian basis sets. This done kinetic energy incident ($E_k$) ranging from 1.56 keV/amu to 1.6 MeV/amu. $S_e$ as average over geometrically pre-sampled short ion trajectories. $S_e(E_k)$ values were found rapidly converge...

The detailed structure and clustering free energy of aerosol particles are important for understanding new particle formation from molecules ions in the atmosphere. In this paper, configurations H2SO4 ·HSO−4 dimer were sampled with meta-dynamics aided ab initio molecular dynamics (MTD-AIMD) simulations. Based on rigid rotor harmonic oscillator (RRHO) approximation law mass action, binding energies (ΔG) most stable configuration calculated three atmospheric circumstances, i.e. at ground level...

A stochastic resonance in ferroelectrics induced by spatial noise (electric random fields) is presented. Starting from a microscopic Hamiltonian of multiple potential well system subject to an external field and internal noise, we demonstrate that the susceptibility, phonon occupancy overcooled temperature show resonant amplifications spatially fields.