Early and Late Effects of Low-Dose X-ray Exposure in Human Fibroblasts: DNA Repair Foci, Proliferation, Autophagy, and Senescence.

The effects of low-dose radiation exposure remain a controversial topic in radiation biology. This study compares early (0.5, 4, 24, 48, and 72 h) and late (5, 10, and 15 cell passages) post-irradiation changes in γH2AX, 53BP1, pATM, and p-p53 (Ser-15) foci, proliferation, autophagy, and senescence in primary fibroblasts exposed to 100 and 2000 mGy X-ray radiation.

Dose-Dependent Shift in Relative Contribution of Homologous Recombination to DNA Repair after Low-LET Ionizing Radiation Exposure: Empirical Evidence and Numerical Simulation.

Understanding the relative contributions of different repair pathways to radiation-induced DNA damage responses remains a challenging issue in terms of studying the radiation injury endpoints. The comparative manifestation of homologous recombination (HR) after irradiation with different doses greatly determines the overall effectiveness of recovery in a dividing cell after irradiation, since HR is an error-free mechanism intended to perform the repair of DNA double-strand breaks (DSB) during S/G2 phases of the cell cycle. In this article, we present experimentally observed evidence of dose-dependent shifts in the relative contributions of HR in human fibroblasts after X-ray exposure at doses in the range 20-1000 mGy, which is also supported by quantitative modeling of DNA DSB repair.

Residual Foci of DNA Damage Response Proteins in Relation to Cellular Senescence and Autophagy in X-Ray Irradiated Fibroblasts.

DNA repair (DNA damage) foci observed 24 h and later after irradiation are called "residual" in the literature. They are believed to be the repair sites for complex, potentially lethal DNA double strand breaks. However, the features of their post-radiation dose-dependent quantitative changes and their role in the processes of cell death and senescence are still insufficiently studied.

Growth Mechanism of Semipolar AlN Layers by HVPE on Hybrid SiC/Si(110) Substrates.

In this work, the growth mechanism of aluminum nitride (AlN) epitaxial films by hydride vapor phase epitaxy (HVPE) on silicon carbide (SiC) epitaxial layers grown on silicon (110) substrates is investigated. The peculiarity of this study is that the SiC layers used for the growth of AlN films are synthesized by the method of coordinated substitution of atoms. In this growth method, a part of the silicon atoms in the silicon substrate is replaced with carbon atoms.

Dielectric Function and Magnetic Moment of Silicon Carbide Containing Silicon Vacancies.

In this work, silicon carbide layers containing silicon vacancies are grown by the Method of Coordinated Substitution of Atoms (MCSA). The main idea of this fundamentally new method is that silicon vacancies are first created in silicon, which is much simpler, and only then is silicon converted into silicon carbide by chemical reaction with carbon monoxide. The dielectric function of silicon carbide containing silicon vacancies, grown on both n- and p-type silicon substrates, is measured for the first time.

Spin Polarization and Magnetic Moment in Silicon Carbide Grown by the Method of Coordinated Substitution of Atoms.

In the present work, a new method for obtaining silicon carbide of the cubic polytype 3C-SiC with silicon vacancies in a stable state is proposed theoretically and implemented experimentally. The idea of the method is that the silicon vacancies are first created by high-temperature annealing in a silicon substrate Si(111) doped with boron B, and only then is this silicon converted into 3C-SiC(111), due to a chemical reaction with carbon monoxide CO. A part of the silicon vacancies that have bypassed "chemical selection" during this transformation get into the SiC.

Anomalous Properties of the Dislocation-Free Interface between Si(111) Substrate and 3C-SiC(111) Epitaxial Layer.

Thin films of single-crystal silicon carbide of cubic polytype with a thickness of 40-100 nm, which were grown from the silicon substrate material by the method of coordinated substitution of atoms by a chemical reaction of silicon with carbon monoxide CO gas, have been studied by spectral ellipsometry in the photon energy range of 0.5-9.3 eV.

The Forest Observation System, building a global reference dataset for remote sensing of forest biomass.

Forest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS).

Implementation of transformed lenses in bed of nails reducing refractive index maximum value and sub-unity regions.

Transformation optics with quasi-conformal mapping is applied to design a Generalized Maxwell Fish-eye Lens (GMFEL) which can be used as a power splitter. The flattened focal line obtained as a result of the transformation allows the lens to adapt to planar antenna feeding systems. Moreover, sub-unity refraction index regions are reduced because of the space compression effect of the transformation, reducing the negative impact of removing those regions when implementing the lens.