Detecting dipolarity of the geomagnetic field in the paleomagnetic record.

Recovering the geomagnetic field strength in the past is key to understanding deep Earth dynamics and detecting potential geodynamo regimes throughout the history of Earth. To better constrain the predictive power of the paleomagnetic record, we propose an approach based on the analysis of the dependency between geomagnetic field strength and inclination (angle made by the horizontal with the field lines). Based on the outcomes of statistical field models, we show that these two quantities should correlate for a wide range of Earth-like magnetic fields, even with enhanced secular variation, persistent nonzonal components, and severe noise contamination.

Fully discrete approximation schemes for rate-independent crack evolution.

Over the past two decades, several distinct solution concepts for rate-independent evolutionary systems driven by non-convex energies have been suggested in an attempt to model properly jump discontinuities in time. Much attention has been paid in this context to the modelling of crack propagation. This paper studies two fully discrete (in time and space) approximation schemes for the rate-independent evolution of a single crack in a two-dimensional linear elastic material.

Modulation of the Directionality of Hole Transfer between the Base and the Sugar-Phosphate Backbone in DNA with the Number of Sulfur Atoms in the Phosphate Group.

This work shows that S atom substitution in phosphate controls the directionality of hole transfer processes between the base and sugar-phosphate backbone in DNA systems. The investigation combines synthesis, electron spin resonance (ESR) studies in supercooled homogeneous solution, pulse radiolysis in aqueous solution at ambient temperature, and density functional theory (DFT) calculations of in-house synthesized model compound dimethylphosphorothioate (DMTP(O)═S) and nucleotide (5'--methoxyphosphorothioyl-2'-deoxyguanosine (G-P(O)═S)). ESR investigations show that DMTP(O)═S reacts with Cl to form the σσ* adduct radical -P-S[Formula: see text]Cl, which subsequently reacts with DMTP(O)═S to produce [-P-S[Formula: see text]S-P-].

The mechanism of organic radical oxidation catalysed by gold nanoparticles.

Metal nanoparticles can catalyze reactions involving organic free radicals. From the first studies focused on the catalytic reduction of water by free radicals until today, the catalytic oxidation of organic radicals has not received attention. In this work, we present the results on the catalytic activity of gold nanoparticles in the oxidation of 2-propanol to acetone and acetanilide hydroxylation during water radiolysis.

Dielectric Characteristics, Electrical Conductivity and Solvation of Ions in Electrolyte Solutions.

Solvation and association of ions in solutions largely depend on the dielectric properties of the solvent, the distance between ions in solutions, and temperature. This paper considers the effect of temperature on static dielectric constant (DC), dipole dielectric relaxation (DR) time, and limiting (ultimate) high frequency (HF) electrical conductivity (EC) of water and some polar solvents. In the investigated temperature range (0-370 °C), the static DC and DR time of water decrease, and limiting HF EC passes through a maximum at 250-300 °C with temperature growth.

Selective Oxidation of Transient Organic Radicals in the Presence of Gold Nanoparticles.

The ability of gold nanoparticles (AuNPs) to catalyze reactions involving radicals is poorly studied. However, AuNPs are used in applications where chemical reactions involving transient radicals occur. Herein, we investigate AuNPs' catalytic effect on 2-propanol oxidation and acetanilide hydroxylation in aqueous solutions under ionizing radiation at room temperature.

Reaction Mechanisms of the Degradation of Fluoroethylene Carbonate, an Additive of Lithium-Ion Batteries, Unraveled by Radiation Chemistry.

Numerous additives are used in the electrolytes of lithium-ion batteries, especially for the formation of an efficient solid electrolyte interphase at the surface of the electrodes. Understanding the degradation processes of these compounds is thus important; they can be seen through radiolysis. In the case of fluoroethylene carbonate (FEC), picosecond pulse radiolysis experiments evidenced the formation of FEC .

Confined water radiolysis in aluminosilicate nanotubes: the importance of charge separation effects.

Imogolite nanotubes are potentially promising co-photocatalysts because they are predicted to have curvature-induced, efficient electron-hole pair separation. This prediction has however not yet been experimentally proven. Here, we investigated the behavior upon irradiation of these inorganic nanotubes as a function of their water content to understand the fate of the generated electrons and holes.

On the Primary Water Radicals' Production in the Presence of Gold Nanoparticles: Electron Pulse Radiolysis Study.

Gold nanoparticles are known to cause a radiosensitizing effect, which is a promising way to improve radiation therapy. However, the radiosensitization mechanism is not yet fully understood. It is currently assumed that gold nanoparticles can influence various physical, chemical, and biological processes.

One Way Traffic: Base-to-Backbone Hole Transfer in Nucleoside Phosphorodithioate.

Invited for the cover of this issue are the groups of Roman Dembinski, Mehran Mostafavi, and Amitava Adhikary at the Polish Academy of Sciences, Université Paris-Saclay, and Oakland University. The image depicts a doughnut as a way of illustrating the hole transfer process. Read the full text of the article at 10.

One Way Traffic: Base-to-Backbone Hole Transfer in Nucleoside Phosphorodithioate.

The directionality of the hole-transfer processes between DNA backbone and base was investigated by using phosphorodithioate [P(S )=S] components. ESR spectroscopy in homogeneous frozen aqueous solutions and pulse radiolysis in aqueous solution at ambient temperature confirmed initial formation of G -P(S )=S. The ionization potential of G-P(S )=S was calculated to be slightly lower than that of guanine in 5'-dGMP.

Diffraction patterns from opaque planar objects simulated with Maggi-Rubinowicz method and angular spectrum theory.

The Maggi-Rubinowicz method (MRM) is a useful tool to compute diffraction patterns from opaque planar objects. We adapted the MRM to planar rectangles. In the first part of this study, differences between diffraction patterns, both the intensity and the phase distributions, from a tilted rectangle and from the square having the same orthogonal projection on the observation plane, have been analyzed.

Stability of equidimensional pseudo-single-domain magnetite over billion-year timescales.

Interpretations of paleomagnetic observations assume that naturally occurring magnetic particles can retain their primary magnetic recording over billions of years. The ability to retain a magnetic recording is inferred from laboratory measurements, where heating causes demagnetization on the order of seconds. The theoretical basis for this inference comes from previous models that assume only the existence of small, uniformly magnetized particles, whereas the carriers of paleomagnetic signals in rocks are usually larger, nonuniformly magnetized particles, for which there is no empirically complete, thermally activated model.

Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain.

Double-strand break repair and genetic recombination in topoisomerase and primase mutants of bacteriophage T4.

The effects of primase and topoisomerase II deficiency on the double-strand break (DSB) repair and genetic recombination in bacteriophage T4 were studied in vivo using focused recombination. Site-specific DSBs were induced by SegC endonuclease in the rIIB gene of one of the parents. The frequency/distance relationship was determined in crosses of the wild-type phage, topoisomerase II mutant amN116 (gene 39), and primase mutant E219 (gene 61).

Mismatch repair in recombination of bacteriophage T4.

Abstract The review focuses on the mechanism of mismatch repair in bacteriophage T4. It was first observed in T4 as an extra recombination mechanism, which contributed to the general recombination only when particular rII mutations were used as genetic markers (high-recombination markers), whereas it was inactive toward other rII mutations (low-recombination markers). This marker-dependent recombination pathway was identified as a repair of mismatches in recombinational heteroduplexes.

[Personality identification based on the outcomes of mass casualty events].

This study concerns the problem of personality identification based on the outcomes of mass casualty events. New organizational measures are proposed to optimize the work with cadaveric materials. Specifically, they envisage creation of four major working groups and organization of their cooperation along the following lines: collection and delivery of postmortem information, systematization of antemortal information, and functioning of the identification centre.

Double-strand break repair and recombination-dependent replication of DNA in bacteriophage T4 in the absence of UvsX recombinase: replicative resolution pathway.

The effects of mutations in bacteriophage T4 genes uvsX and 49 on the double-strand break (DSB)-promoted recombination were studied in crosses, in which DSBs were induced site-specifically within the rIIB gene by SegC endonuclease in the DNA of only one of the parents. Frequency of rII+ recombinants was measured in two-factor crosses of the type i×ets1 and in three-factor crosses of the type i×ets1 a6, where ets1 is an insertion in the rIIB gene carrying the cleavage site for SegC; i's are rIIB or rIIA point mutations located at various distances (12-2040 bp) from the ets1 site, and a6 is rIIA point mutation located at 2040 bp from ets1. The frequency/distance relationships were obtained in crosses of the wild-type phage and of the amber mutant S17 (gene uvsX) and the double mutant S17 E727 (genes uvsX and 49).

Endonuclease VII is a key component of the mismatch repair mechanism in bacteriophage T4.

In previous papers we described an extra recombination mechanism in T4 phage, which contributed to general recombination only when particular mutations were used as geneticmarkers (high recombination or HR markers), whereas it was practically inactive towards other rIIB mutations (low recombination or LR markers). This marker-dependent recombination pathway was identified as a repair of mismatches in recombination heteroduplexes. We suggested that the first step in this pathway, recognition and incision of the mismatch, is performed by endonuclease VII (endo VII) encoded by the T4 gene 49.

On the mutagenicity of homologous recombination and double-strand break repair in bacteriophage.

The double-strand break (DSB) repair via homologous recombination is generally construed as a high-fidelity process. However, some molecular genetic observations show that the recombination and the recombinational DSB repair may be mutagenic and even highly mutagenic. Here we developed an effective and precise method for studying the fidelity of DSB repair in vivo by combining DSBs produced site-specifically by the SegC endonuclease with the famous advantages of the recombination analysis of bacteriophage T4 rII mutants.

Theoretical analysis of flux amplification by soft magnetic material in a putative biological magnetic-field receptor.

Birds are endowed with a magnetic sense that allows them to detect Earth's magnetic field and to use it for orientation. Physiological and behavioral experiments have shown the upper beak to host a magnetoreceptor. Putative magnetoreceptive structures in the beak are nerve terminals that each contain a dozen or so of micrometer-sized clusters of superparamagnetic nanocrystals made of magnetite/maghemite and numerous electron-opaque platelets filled with a so far unidentified, amorphous ferric iron compound.

Biological species is the only possible form of existence for higher organisms: the evolutionary meaning of sexual reproduction.

Consistent holistic view of sexual species as the highest form of biological existence is presented. The Weismann's idea that sex and recombination provide the variation for the natural selection to act upon is dominated in most discussions of the biological meaning of the sexual reproduction. Here, the idea is substantiated that the main advantage of sex is the opposite: the ability to counteract not only extinction but further evolution as well.

[In vivo study of fidelity of DNA double-strand break repair in bacteriophage T4].

A method for in vivo studying the fidelity of DNA double-strand break (DSB) repair in bacteriophage T4 has been developed. The frequency of reversion of rII mutations to the wild phenotype was measured in i segC+ x i ets 1 segCDelta crosses, where ets 1 is an insertion in the initial part of the rII gene carrying a sequence recognized by SegC endonuclease; i designates a rIIB or rIIA mutation located at some distance from ets 1, and segCDelta is a deletion in the segC gene. In such cross, a DSB occurs in the site of ets 1.